JP7052595B2 - Cutting device and cutting method - Google Patents

Description

The present invention relates to a cutting device and a cutting method, and more particularly to a cutting device and a cutting method capable of cutting a metal member by heat using a plasma arc or the like while using a refrigerant such as water.

A cutting method using heat, such as plasma cutting, may be used for cutting a plate-shaped metal member. As described in Patent Document 1, plasma cutting is usually performed in the atmosphere, but there are cases where an underwater plasma cutting is performed by providing a cutting pool or the like and arranging a metal member in water.

Japanese Unexamined Patent Publication No. 5-23859

As described in Patent Document 1, by performing cutting using heat in water, it is possible to suppress the influence of heat on other parts of the object to be cut. Further, as shown in FIG. 12, it is also possible to prevent the metal material M1 melted by heat from adhering to other parts of the object to be cut to form the adhered matter M2. However, the metal material M1 melted by heat becomes fine powder instead of becoming deposits M2 and is dispersed in water. Dust generated during cutting is also dispersed in water.

When cutting on a plurality of surfaces of the object to be cut, a holding means for holding the object to be cut may be installed in a water tank for storing water so as to be rotatable around the axis. For example, when plasma cutting is performed on a metal member having a shape having faces facing each other, such as a U-shaped cross section as shown in FIG. 12, such a rotary holding means is often used. .. A sealing member for preventing water leakage is provided at a position where the holding means is supported by the wall surface of the water tank. In such a case, if the metal powder or dust derived from the metal material M1 melted by heat is dispersed in the water stored in the water tank, the life of the sealing member will be shortened due to the influence of the metal powder or dust. It tends to be short. Then, it becomes necessary to replace the seal member frequently. If many work steps are required each time the sealing member is replaced, the maintenance of the cutting device becomes complicated. In addition, frequent replacement of the sealing member tends to lead to a misalignment between the cutting means such as a plasma torch and the holding means.

The problem to be solved by the present invention is to replace the seal member provided on the support portion of the holding means in the cutting device for cutting the object to be cut held by the holding means that can rotate the shaft using a liquid refrigerant such as water. It is an object of the present invention to provide a cutting device that can be easily performed while suppressing the occurrence of misalignment, and a cutting method using such a cutting device.

In order to solve the above problems, the cutting device according to the present invention applies heat to a part of a plate-shaped metal material, and stores a cutting means for cutting the metal material in the part and a liquid refrigerant. In a cutting device having a liquid storage means for holding a liquid to be cut, and a holding means for holding an object to be cut made of a metal material in a cutting position by the cutting means, the holding means is used. The cutting device is further made of a string-like material and has a shaft portion that is rotatably supported by the side wall in a state where the tip portion is projected to the outside of the side wall of the liquid storage means, and is outside the side wall. A seal member arranged around the outer periphery of the shaft portion to prevent the liquid refrigerant from leaking from between the shaft portion and the side wall, and the seal member from the outside of the side wall to the side wall. It has a seal holding member that can be divided into a plurality of parts in the circumferential direction of the shaft portion to be pressed.

Here, the cutting device has a transporting means in the liquid storage means, and the transporting means is separated into the liquid refrigerant when the object to be cut is cut by the cutting means. It is preferable that the cut pieces are transported to the outside of the liquid storage means.

It is said that a plurality of the sealing members are provided along the axial direction of the shaft portion, and the positions of the ends of the string-shaped materials constituting each sealing member are displaced from each other along the circumference of the shaft portion. good.

The side wall is provided with a notch portion opened at the upper end edge of the side wall, and the shaft member is supported in a state of being housed in the notch portion, and is supported on the upper end edge of the side wall. It is preferable that the notch can be accessed through the provided opening.

The string-shaped material constituting the sealing member may be a braided body made of a fiber material impregnated with a lubricant.

Here, the cutting means may be a plasma cutting torch. In this case, the plasma cutting torch may use oxygen as an operating gas.

The cutting method according to the present invention is made of a metal material by using a cutting device as described above, and is separated from the first plate-shaped portion and the first plate-shaped portion into the first plate-shaped portion. In a cutting method for cutting an object to be cut having a second plate-shaped portion facing each other, one of the first plate-shaped portion and the second plate-shaped portion is used as a target portion and the other as a standby portion. The standby portion is arranged in the liquid refrigerant, and the target portion is cut outside the liquid refrigerant in a state where the target portion is arranged outside the liquid refrigerant.

Here, the surface of the target portion facing the standby portion may be arranged so as not to come into contact with the liquid refrigerant.

With the object to be cut fixed, it is preferable to cut the object to be cut while moving the cutting means with respect to the object to be cut.

The cutting means is a plasma cutting torch, and cuts the target portion while moving the cutting means along the surface of the target portion with the starting edge, which is one part of the end edge of the target portion, as a starting point. At that time, the cutting means is arranged outside the starting edge, and the cutting means is moved toward the starting edge in a state where the plasma arc is emitted from the cutting means, and the cutting means and the object to be cut are used. When the value of the current flowing between the two starts to increase, it is advisable to increase the moving speed of the cutting means.

The cutting means is a plasma cutting torch, and while moving the cutting means along the surface of the target portion, the target portion is cut with the end edge, which is one part of the end edge of the target portion, as an end point. When the current value flowing between the cutting means and the object to be cut begins to decrease after the cutting by the cutting means reaches the end edge, the cutting means before the current value becomes zero. It is advisable to stop the emission of the plasma arc from.

When the target portion is cut by the cutting means, the energy density of the heat given to the object to be cut by the cutting means and the cutting means are described so that the smoothness of the target portion and the standby portion is increased. It is preferable to adjust at least one of the moving speed of the cutting means when cutting the object to be cut while moving the object to be cut.

The first step of cutting the first plate-shaped portion and the second plate-shaped portion using the first plate-shaped portion as the target portion and the second plate-shaped portion as the standby portion. Is the target portion, the first plate-shaped portion is the standby portion, and one of the second steps of cutting the second plate-shaped portion is performed, and then the cut is performed. It is advisable to change the arrangement of objects and perform the other process.

It is preferable to use a plurality of the cutting means to simultaneously cut a plurality of objects to be cut held by the common holding means.

The object to be cut is a pair of metal members having a first plate-shaped portion and a second plate-shaped portion in a bending portion formed by bending a plate material into a U-shaped cross section, and the cutting means is used. After cutting the surplus at the edge of the bent portion of the pair of metal members, the pair of metal members may be abutted against each other and fixed at the edge.

In the cutting device according to the above invention, by holding the object to be cut by the holding means provided in the liquid storage means so that the axis can be rotated, the object to be cut is rotated by the axis to change the arrangement, and the cutting means is used. You can cut. At this time, the sealing member suppresses the leakage of the liquid refrigerant from the portion of the side wall of the liquid storage means that supports the shaft portion of the holding means.

When cutting a metal material by heat using a liquid refrigerant as in this cutting device, the metal powder and dust generated when cutting the object to be cut dissolves and disperses in the liquid refrigerant, so the seal is used. The life of the member tends to be shortened, and it tends to be necessary to replace the sealing member frequently. However, because the seal member is not an annular shape but is formed in a string shape, and because the seal holding portion can be divided in the circumferential direction of the shaft portion, the member attached to the tip of the shaft portion can be used. The seal member and the seal holding member can be attached and detached from the side of the shaft portion, and the seal member can be replaced without removing or disassembling. As a result, the sealing member can be easily replaced, and the possibility that the positional relationship between the holding means and the cutting means changes due to the replacement of the sealing member can be reduced.

Here, the cutting device has a transporting means in the liquid storage means, and when the transporting means cuts the object to be cut by the cutting means, the cut pieces separated into the liquid refrigerant are stored in the liquid. When transported to the outside of the means, it avoids the accumulation of unnecessary cutting pieces separated by cutting in the liquid storage means, and continuously and efficiently cuts a large number of objects to be cut. Can be carried out.

If a plurality of sealing members are provided along the axial direction of the shaft portion and the positions of the ends of the string-shaped materials constituting each sealing member are displaced from each other along the circumference of the shaft portion, the sealing member is string-shaped. It is possible to prevent the liquid refrigerant from leaking through the portion where the ring shape of the seal member is cut, which corresponds to the end portion of the member.

The side wall is provided with a notch that opens at the upper end edge of the side wall, and the shaft member is supported in a state of being housed in the notch, and the opening provided at the upper end edge of the side wall. If it is possible to enter and exit the notch portion via the above, the holding means can be removed from the liquid storage means by lifting the shaft member in a state where the seal member and the seal holding member are removed. Therefore, it is possible to easily attach / detach the holding means for maintenance or the like.

Further, when the string-shaped material constituting the sealing member is made of a braided body made of a fiber material impregnated with a lubricant, it is easy to achieve high sealing performance by the sealing member.

When the cutting means is a plasma cutting torch, it is possible to cut the object to be cut at high speed and with high accuracy by using a relatively simple facility. In plasma cutting, when cutting the object to be cut, dust and metal powder are likely to be dispersed in the liquid refrigerant. Even if the life of the sealing member is shortened due to the dispersion of dust or metal powder, it is possible to improve the convenience of replacing the sealing member and suppress the misalignment due to the replacement of the sealing member.

In this case, if the plasma cutting torch uses oxygen as the operating gas, a material made of various metal materials can be applied as the object to be cut, and cutting is achieved even when the plate thickness is large. can do. In addition, by using oxygen as the operating gas, the injection of the metal material melted by the plasma arc occurs particularly strongly, and the metal powder is likely to be dispersed in a large amount in the liquid refrigerant. Even if frequent replacement is required, the sealing member can be replaced easily and with less misalignment.

In the cutting method according to the above invention, since the object to be cut is cut by using the cutting device as described above, the dust and metal powder generated by the cutting are dispersed in the liquid refrigerant to seal the material. Even if the life of the member is shortened, the seal member can be replaced easily and while suppressing the misalignment of the holding means due to the effect of the shapes of the seal member and the seal holding member.

Further, when cutting the target portion selected from the first plate-shaped portion and the second plate-shaped portion, the standby portion, which is the other plate-shaped portion facing the target portion, is placed in a liquid refrigerant such as water. On the other hand, since the target part is placed outside the liquid refrigerant, the standby part is placed inside the liquid refrigerant, so that even if heat is applied to the target part when cutting the target part. Due to the cooling effect of the liquid refrigerant, the heat does not easily affect the standby unit. Further, the metal material melted down when the target portion is cut is cooled by the liquid refrigerant and solidified, so that it does not easily adhere to the standby portion. In this way, the influence caused by the cutting of the target portion on the standby portion is suppressed by the presence of the liquid refrigerant. Further, by cutting the object to be cut while cooling it with a liquid refrigerant, it is possible to obtain an effect of suppressing the deformation of the object to be cut due to the influence of heat given by the cutting means.

On the other hand, since the target portion is cut while it is outside the liquid refrigerant, the smoothness of the cut surface decreases due to contact with the liquid refrigerant, and the hardness of the cut portion increases due to quenching after cutting. Is avoided. In this way, the liquid refrigerant is less likely to affect the cut portion of the target portion.

When the surface of the target portion facing the standby portion is arranged so as not to come into contact with the liquid refrigerant, it is particularly effective to prevent the liquid refrigerant from affecting the cut portion in the target portion. It can be avoided.

When cutting the object to be cut while moving the cutting means with respect to the object to be cut while the object to be cut is fixed, the object to be cut is large or the cutting shape is complicated. Also, it is easy to cut.

The cutting means is a plasma cutting torch, and when cutting the target portion while moving the cutting means along the surface of the target portion, starting from the starting end edge which is one part of the end edge of the target portion. With the cutting means placed on the outside of the edge and the plasma arc emitted from the cutting means, the cutting means is moved toward the starting edge, and when the current value flowing between the cutting means and the object to be cut begins to rise, cutting is performed. When increasing the moving speed of the means, cutting can be performed under stable conditions from the beginning of cutting at the starting edge. In addition, it is easy to protect the electrodes of the plasma cutting torch from unnecessary wear.

The cutting means is a plasma cutting torch, and when cutting the target portion with the end edge, which is one part of the end edge of the target portion, as the end point while moving the cutting means along the surface of the target portion. When the current value flowing between the cutting means and the object to be cut begins to decrease after the cutting by the means reaches the end edge, the emission of the plasma arc from the cutting means is stopped before the current value becomes zero. In the meantime, cutting can be performed under stable conditions until the cutting is completed at the terminal edge.

When the target portion is cut by the cutting means, the energy density of the heat given to the object to be cut by the cutting means and the cutting means are moved with respect to the object to be cut so that the smoothness of the target portion and the standby portion is improved. However, when adjusting at least one of the moving speed of the cutting means when cutting the object to be cut, the smoothness of the target portion and the standby portion is reduced due to the influence of the cutting, and the object to be cut after cutting. It is easy to avoid affecting the quality of.

The first step of cutting the first plate-shaped portion with the first plate-shaped portion as the target portion and the second plate-shaped portion as the standby portion, and the second plate-shaped portion as the target portion, the first Of the second step of cutting the second plate-shaped portion with one plate-shaped portion as the standby portion, after performing one of the steps, the arrangement of the object to be cut is changed and the other step is performed. When doing so, both the first plate-shaped portion and the second plate-shaped portion can be cut by using a common cutting means, so that the first plate-shaped portion and the second plate-shaped portion in the object to be cut can be cut. It is possible to easily perform a process of cutting both of the plate-shaped portions of the above into a desired shape.

When multiple cutting means are used to simultaneously cut a plurality of objects to be cut held by a common holding means, it is efficient to cut the objects to be cut of a plurality of individuals at the same time. Cutting can be performed on a large number of individuals.

The object to be cut is a pair of metal members having a first plate-shaped portion and a second plate-shaped portion in a bending portion formed by bending a plate material into a U-shaped cross section, and a pair by cutting means. If a pair of metal members are abutted against each other and fixed at the edge of the bent portion of the metal member after cutting the surplus wall, the surplus at the edge of the bent portion is fixed. The meat can be cut in a state where the influence on the first plate-shaped portion and the second plate-shaped portion is small. By abutting the pair of metal members having high-quality end edges thus obtained against each other and fixing them by welding or the like, the accuracy of the butt and fixing can be improved. A typical example of a product manufactured through a process of cutting a pair of metal members with excess meat, abutting them, and fixing them by welding is an axle housing for accommodating a vehicle differential gear. ..

It is a figure explaining the structure of the cutting apparatus which concerns on one Embodiment of this invention, (a) is a front view, (b) is a side view. Both indicate a state in which cutting is being performed. It is a side view explaining the structure of the said cutting apparatus. It shows a state in which cutting is not performed, and the rotational state of the holding jig is different from that in FIG. It is a figure which shows the state which held the pair of axle housing main body material by the holding jig in the said cutting apparatus, (a) is a perspective view, (b) is a plan view. It is a figure explaining the cutting method which concerns on one Embodiment of this invention, and is the side view which shows the state in the vicinity of the part where cutting is performed. It is a figure explaining the said cutting method, (a) shows the state before cutting, (b) shows the state after cutting. It is a figure which shows the state which a pair of main body materials are cut at the same time. It is an exploded perspective view which shows the seal part in the said cutting apparatus. It is an enlarged sectional view which shows the said seal part. It shows a cut plane parallel to the vertical direction, including the center of rotation of the central axis of the holding jig. It is a figure explaining each parameter measured as an index of deformation in an Example. It is a figure explaining the evaluation of the smoothness of the upper surface and the lower surface in an Example. It is a figure which shows the relationship between the energy density and the cutting speed, and the quality of a cutting condition. It is a figure explaining plasma cutting in the atmosphere.

Hereinafter, the cutting apparatus and the cutting method according to the embodiment of the present invention will be described in detail with reference to the drawings.

[Example of object to be cut]
First, the object to be cut (work) to be cut in the cutting device and the cutting method according to the embodiment of the present invention will be described.

The work to be cut is made of a metal material, and has a first plate-shaped portion and a second plate-shaped portion as a portion having a plate-shaped structure. The first plate-shaped portion and the second plate-shaped portion are separated from each other and face each other. The first plate-shaped portion and the second plate-shaped portion may face each other with their surfaces substantially parallel to each other, or may have an angle between the mutual surfaces, and one of them (for example, the first plate-shaped portion). When the surface of the plate-shaped portion) is arranged substantially horizontally, the surface of the other (second plate-shaped portion) exists below the portion where the surface (first plate-shaped portion) is scheduled to be cut. Anything that does.

The first plate-shaped portion and the second plate-shaped portion may be connected in any way as long as they are separated from each other. For example, a form in which the first plate-shaped portion and the second plate-shaped portion are connected at the mutual edge, that is, a form in which the work has a U-shaped (U-shaped) cross section can be mentioned.

As an example of a suitable work, a main body material which is a metal member constituting the axle housing can be mentioned. The axle housing is assembled to the rear axle portion of a large vehicle such as a truck, and accommodates the axle, the differential gear, and the like. The main body portion of the axle housing is made of a pair of main body materials 90, 90 having substantially symmetrical shapes as shown in FIG. 6 and the like.

The pair of main body members 90 each have a body portion 90a and tubular portions 90b and 90b formed integrally. The body portion 90a is formed by bending a steel plate into a semi-cylindrical shape (substantially U-shaped in cross section) and bulging into a substantially semi-circular ring shape. The tubular portions 90b and 90b are integrally formed at both ends of the body portion 90a, and the steel plate is bent into a semi-cylindrical shape in the same manner as the body portion 90a, and the tubular portion 90b is basically in the shape of a half-width cylinder. Here, the upper and lower upper surfaces 91 and the lower surface 92 that form the body portion 90a and the tubular portions 90b, 90b are the first plate-shaped portion and the second plate-shaped portion at the time of cutting.

Each pair of main body materials 90 can be manufactured by bending a steel plate by press forming. Then, the surplus thickness is cut with respect to the longitudinal end edges 91a and 92a of the upper surface 91 and the lower surface 92, which are the edge edges of the bent portion, by the cutting method according to the embodiment of the present invention. Then, in the new longitudinal end edges 91d and 92d obtained by cutting, a pair of main body materials 90 and 90 are butted against each other, and the butted portions are welded to each other to fix each other. In this way, the main body portion of the axle housing having a substantially annular body portion and a substantially square tubular portion is manufactured. Further, the axle housing as a product can be completed by attaching accessories and the like.

[Configuration of cutting device]
Next, the cutting device according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3.

1 and 2 show an outline of the cutting device 1 according to the embodiment of the present invention. The cutting device 1 includes a plasma cutting torch 10 as a cutting means, a numerical control (NC) device 20 as a driving means, a holding jig 30 as a holding means, a water tank 40 as a liquid storage means, and a transporting means. It has a conveyor 50 and a rotary drive unit 60. Here, FIG. 1 shows a state in which cutting is performed by the plasma cutting torch 10. FIG. 2 shows a state in which cutting is not performed, and the rotational state of the holding jig 30 is different from that in FIG. 1 (a).

The plasma cutting torch 10 emits a plasma arc A and can cut a plate-shaped metal material by the heat of the plasma arc A. Preferably, oxygen is used as an operating gas so that it can be applied to various metal materials and can cut even a thick metal material having a plate thickness of more than 10 mm at high speed. When oxygen is used as the operating gas, the operating gas may be composed of oxygen alone or a mixed gas containing oxygen as a main component. Further, air or the like may be used as the assist gas as appropriate. The cutting device 1 according to the present embodiment includes two plasma cutting torches 10.

The NC device 20 holds each of the two plasma cutting torch 10s and gives the motion D1 to the plasma above the cutting target surface of the work (here, the axle housing main body material 90) and along the cutting target surface. Move the cutting torch 10. Cutting of the work into a desired shape can be achieved according to numerical control by a control unit (not shown).

The holding jig 30 holds the work in the water tank 40 and holds the work at a position where it can be cut by the plasma cutting torch 10. Here, as shown in FIG. 3 and the like, the holding jig 30 can hold two axle housing main body materials 90 and 90 as works at the same time in a substantially mirror-symmetrical arrangement. The work may be held by any method, but using a gripping tool (not shown), both ends of the main body material 90 in the longitudinal direction are sandwiched between the holding jig 30 and the gripping tool, and an air cylinder is appropriately used. By pressing the gripping tool against the holding jig 30 using an or the like, the main body material 90 can be firmly held.

Further, the holding jig 30 can change the arrangement of the held main body material 90. That is, the motion D2 for rotating the central axis (shaft portion) 31 by 180 ° can be performed while holding the main body material 90, and the upper surface 91 (first plate-shaped portion) can be moved upward as shown in FIG. Between the first arrangement facing the plasma cutting torch 10 and the second arrangement facing the plasma cutting torch 10 with the opposite lower surface 92 (second plate-shaped portion) facing upward. It can be transitioned. The intermediate state of the transition corresponds to the rotational state shown in FIG. The holding jig 30 can perform operations other than changing the arrangement of the main body material 90. For example, the position of the main body material 90 in the water tank 40 can be adjusted, or the main body material 90 to be cut can be replaced. It is possible to do. The rotation of the holding jig 30 is driven by the rotation driving unit 60 attached to the central shaft 31.

The water tank 40 can store water W as a liquid refrigerant. While cutting with the plasma cutting torch 10, the water level is such that one surface (standby portion) of the upper surface 91 and the lower surface 92 of the main body material 90 is placed in the water W as shown in FIGS. However, the other surface (target portion) is maintained so as to be placed outside the water W. The water tank 40 is provided with a recessed portion 42 capable of accommodating an aggregate of the bearing 61, the coupling 62, and the servomotor 63 of the rotary drive unit 60, which will be described later. The inside of the recess 42 is a space outside the water tank 40.

In the conveyor 50, the transport surface 51 is arranged in water along the bottom surface of the water tank 40. Then, the transport surface 51 goes over the side wall 41 of the water tank 40 and extends to the outside of the water tank 40. The cut piece 95 cut and separated by the plasma cutting torch 10 is separated into water from the main body material 90, settles, and rides on the transport surface 51 of the conveyor 50. By driving the motion D3 that directs the transport surface 51 of the conveyor 50 from the inside of the water tank 40 to the outside, the cut pieces 95 can be transported from the inside of the water tank 40 to the outside and discharged to the outside of the water tank.

The rotary drive unit 60 includes bearings 61 and 64, a coupling 62, and a servomotor 63. As shown in FIGS. 7 and 8, one end of the central shaft 31 of the holding jig 30 passes through a notch 43 provided in one of the side walls (41a) of the water tank 40, and is outside the side wall 41a. It stands out. The central shaft 31 is supported by the bearing 61 so as to be rotatable. The tip of the central shaft 31 is coupled to the rotation shaft of the servomotor 63 via the coupling 62. The bearing 61, the coupling 62, and the servomotor 63 are housed in the recessed portion 42 of the water tank 40, so that the bearing 61, the coupling 62, and the servomotor 63 are arranged in the space outside the water tank 40 without interfering with the inclined portion of the conveyor 50.

Similarly, the other end portion of the central shaft 31 also has a tip portion protruding to the outside of the side wall 41b through a notch provided in the side wall 41b facing the side wall 41a. Then, it is supported by a bearing 64 so that the shaft can rotate. By having such a rotation drive unit 60, the shaft rotation of the holding jig 30 holding the axle housing main body materials 90 and 90 can be driven by the servomotor 63.

Sealed portions 70 are provided at the portions where both ends of the central shaft 31 are supported by the side walls 41a and 41b of the water tank 40, respectively, and are stored in the water tank 40 from between the central shaft 31 and the side walls 41a and 41b. It plays a role of suppressing the leakage of the water W to the outside. Details of the configuration of the seal member 70 will be described later.

[Disconnecting method]
Next, the cutting method according to the embodiment of the present invention will be described with reference to FIGS. 1 to 6. Here, the case where the main body material 90 of the axle housing is used as the work to be cut and the surplus wall of the longitudinal end edges 91a and 92a is cut by using the cutting device 1 described above will be dealt with.

First, the holding jig 30 holds the pair of main body materials 90, 90 in a substantially mirror-symmetrical arrangement. Further, water W is stored in the water tank 40. Then, each main body material 90 held by the holding jig 30 is arranged in the water tank 40. At the time of arrangement, the upper surface 91 (first plate-shaped portion) and the lower surface 92 (second plate-shaped portion) of the main body material 90 are kept substantially horizontal.

At this time, as shown in detail in FIG. 4, of the upper surface 91 and the lower surface 92 of each main body material 90, the surface (target portion; in this case, the upper surface 91) where the surplus meat is cut first is in the water tank 40. It is arranged outside the stored water W, that is, above the water surface W1. On the other hand, of the upper surface 91 and the lower surface 92, the surface (standby portion; in this case, the lower surface 92) on which the surplus meat is not cut first is in the water W stored in the water tank 40, that is, below the water surface W1. Place it in. In this way, only a part of the area along the vertical direction of the main body material 90 is arranged in water. It is preferable that the inner side surface 91b of the upper surface 91, that is, the surface facing the lower surface 92 is also arranged above the water surface W1 so as not to come into contact with the water W.

With the main body material 90 arranged and fixed in this way, the surplus thickness of the upper surface 91 is cut using the plasma cutting torch 10. As shown in FIG. 5A, cutting is performed by performing motion D1 of the plasma cutting torch 10 by the NC device 20 along a path determined according to a virtual line to be cut in the main body material 90. .. Here, the virtual line to be cut intersects the longitudinal edge 91a, which is the edge of the main body 90 along the longitudinal direction, from one end to the other end, that is, the longitudinal edge 91a. From the start edge 93 on one side of the opposite edge to the end edge 94 on the other side, set as a continuous line along the longitudinal edge 91a at a position slightly inside the portion where the surplus to be cut exists. Will be done. By cutting along such a virtual line, the cut piece 95 including the surplus portion is separated from the main body material 90 as shown in FIG. 5 (b). Further, by cutting, a new longitudinal edge 91d is formed inside the original longitudinal edge 91a, and the cut surface 91c is exposed. In the present embodiment, as shown in FIG. 6, two NC devices 20 and 20 operate and move the two plasma cutting torches 10 and 10 at the same time, and the pair of main body materials 90 and 90 are operated and moved at the same time. Cut at the same time.

Generally, when cutting a metal material using a plasma cutting torch, a pilot arc having a smaller output than the main arc may be used before the main arc used for cutting the material is generated. In the present embodiment, the pilot arc is emitted from the plasma cutting torch 10 in a state where the plasma cutting torch 10 is arranged outside the main body material 90 with respect to the starting edge 93. From this state, when the plasma cutting torch 10 is moved toward the start edge 93 by the NC device 20, the plasma arc A starts at a position approaching the start edge 93 to some extent, for example, a position about 5 mm outside the start edge 93. Start to bend towards the edge 93. Along with this, a main arc is generated between the electrode of the plasma cutting torch 10 and the metal material of the main body material 90, and the current value flowing between the two starts to increase. As soon as this increase in the current value is detected, the moving speed of the plasma cutting torch 10 by the NC device 20 along the upper surface 91 of the main body material 90 is controlled to be increased.

In this way, from the state where the moving speed of the plasma cutting torch 10 is increased at the start of cutting, the plasma cutting torch 10 is continuously moved by the NC device 20 along the longitudinal edge 91a of the upper surface 91 of the main body material 90. It is moved at a position inside the longitudinal edge 91a, and the surplus portion is continuously cut. Finally, the cut reaches the end edge 94 of the top surface 91. Further, by moving the plasma cutting torch 10 from the terminal edge 94 to the outside of the main body material 90, the main body material 90 is cut through, and the cut piece 95 including the surplus portion is separated from the main body material 90. In the present embodiment, the state in which the plasma arc A is emitted from the plasma cutting torch 10 is maintained even at the moment when the cutting reaches the terminal edge 94 and cuts through the terminal edge 94. After that, the current value flowing between the plasma cutting torch 10 and the main body material 90 begins to decrease with the cut-through. If left as it is, the generation of plasma arc A will eventually stop and the current value will reach zero. However, in the present embodiment, instead of leaving it to stand naturally until the current value becomes zero, when the current value starts to decrease, the plasma cutting torch 10 is forcibly released before the current value becomes completely zero. Control is performed to stop the emission of the plasma arc A and end the operation of the plasma cutting torch 10.

At the time of cutting, the strength of the plasma arc A emitted from the plasma cutting torch 10, that is, the energy density of the heat given to the main body material 90 by the plasma arc A, and the plasma cutting torch 10 are moved along the upper surface 91 by the NC device 20. By changing the moving speed (cutting speed), the cutting conditions change, which affects the quality of the upper surface 91 and the lower surface 92 obtained after cutting. Therefore, at least one of these parameters may be adjusted so that the smoothness of the upper surface 91 and the lower surface 92 becomes high. Preferably, both parameters may be adjusted under such a guideline. In particular, proper selection of the moving speed of the plasma cutting torch 10 has a high effect on improving the smoothness of the upper surface 91 and the lower surface 92. Here, the state in which the upper surface 91 has high smoothness means that the upper surface 91 is roughened due to contact with the cut portion of the water W, or the metal material melted at the time of cutting the upper surface 91 is the inner surface 91b of the upper surface 91. It refers to a state in which the uneven structure on the upper surface 91 is small, such as a protrusion-like or dross-like deposit M2 generated by adhering to the surface 91. The state in which the lower surface 92 has high smoothness means that the lower surface 92 is roughened due to the influence of heat or the like, or a protrusion-like or dross-like deposit generated by the metal material melted down from the upper surface 91 adhering to the inner surface 92b of the lower surface 92. It refers to a state in which the uneven structure on the lower surface 92 such as M2 is small. The values set as the above two parameters may be maintained constant during cutting of one main body material 90, or may be appropriately changed during cutting. The energy density of the plasma arc A can be changed, for example, by adjusting the supply amount of the operating gas.

When the cutting from the start end edge 93 to the end edge 94 is completed, the cut piece 95 including the surplus portion separated from the main body material 90 sinks in the water tank 40. When the settled cut pieces 95 reach the transport surface 51 of the conveyor 50 at the bottom of the water tank 40 and get on the transport surface 51, the cut pieces 95 are transported by the motion D3 of the conveyor 50 and discharged to the outside of the water tank 40. .. In addition, this discharge step may be performed every time the cutting of the upper surface 91 and the lower surface 92 of the main body material 90 is completed, or may be performed after the cutting of both the upper surface 91 and the lower surface 92 is completed. Further, after the cutting of the plurality of pairs of the main body materials 90 is completed, they may be collectively performed as appropriate.

When the cutting of the main body material 90 with respect to the upper surface 91 is completed, the holding jig 30 inverts the main body material 90 by 180 ° by the motion D2 about the central axis 31. Then, the lower surface 92 is arranged as a target portion outside the water W stored in the water tank 40, that is, above the water surface W1. Further, the upper surface 91 is arranged as a standby portion in the water W stored in the water tank 40, that is, below the water surface W1. As in the case where the upper surface 91 is the target portion, the inner side surface 92b of the lower surface 92 is preferably arranged above the water surface W1 so as not to come into contact with the water W. As shown in FIGS. 3 and 6, when the pair of main body materials 90 and 90 are symmetrically held by the common holding jig 30 and the 180 ° arrangement is reversed around the central axis 31, the upper surface 91 The left and right positions of the pair of main body materials 90 and 90 with respect to the central axis 31 are exchanged between the time of cutting and the time of cutting the lower surface 92.

Then, in the same manner as the cutting is performed on the upper surface 91, the lower surface 92 is cut along the longitudinal end edge 92a from the start end edge 93 to the end edge 94 by using the plasma cutting torch 10. A new longitudinal edge 92d is obtained, and the cut piece 95 including the surplus portion is cut off.

When the cutting with respect to the upper surface 91 and the lower surface 92 is completed, the pair of main body materials 90, 90 is removed from the holding jig 30. The removed pair of main body materials 90, 90 are then abutted against each other at the new longitudinal edge 91d, 92d of the upper surface 91 and the lower surface 92 from which the surplus portion has been removed. Then, they are fixed to each other by being welded at the butt portion.

The holding jig 30 after removing the pair of main body materials 90, 90 that has been cut can appropriately hold another pair of main body materials 90, 90 to be cut next. Then, by repeating the above-mentioned cutting process, it is possible to continuously cut a plurality of pairs of main body materials 90, 90.

When cutting the longitudinal end edges 91a and 92a of the main body material 90 of the axle housing using the plasma cutting torch 10, the upper surface 91 of the facing upper surface 91 and the lower surface 92 is set as the target portion to be cut. When the lower surface 92 is a standby portion on the side where cutting is not performed (hereinafter, the same applies to the case where the upper surface 91 and the lower surface 92 are reversed unless otherwise specified in this section), the lower surface 92 is directly below the upper surface 91. Is present, plasma cutting of the upper surface 91 will be performed. At this time, the plasma arc A is strongly ejected below (the back side) of the portion where the upper surface 91 is being cut. Therefore, if the upper surface 91 is cut in the atmosphere, the influence of the heat of the ejected plasma arc A is exerted. There is a possibility that the heated lower surface 92 may be melted, modified, deformed, roughened or the like, which is applied to the lower surface 92. Further, the metal material M1 melted down from the upper surface 91 may be ejected toward the lower surface 92, adhere to the inner side surface 92b of the lower surface 92 and solidify, and become a deposit M2, as shown in FIG. ..

However, in the present embodiment, as shown in FIG. 4, since plasma cutting is performed in a state where the lower surface 92 serving as a standby portion is placed in water W which is a liquid refrigerant, the lower surface 92 is cooled. The heat of the ejected plasma arc A does not easily affect the lower surface 92. Further, the metal material M1 melted down from the upper surface 91 is cooled in water before reaching the lower surface 92 to become a granular solidified product M3, so that adhesion to the inner side surface 92b of the lower surface 92 is suppressed. Due to these effects, when the upper surface 91 is cut, the lower surface 92 is less likely to be affected by heat such as denaturation or to be deteriorated in quality due to the deposit M2 due to the influence of the cutting. The metal material M1 melted down from the upper surface 91 may form deposits M2 not only on the inner side surface 92b of the lower surface 92 but also on the inner side surface 91b of the upper surface 91 (see FIG. 10), but directly below the upper surface 91. By cutting in the presence of water W, the formation of the deposit M2 on the inner side surface 91b of the upper surface 91 can be suppressed due to the cooling effect of the metal material M1.

On the other hand, if the entire axle housing body 90, that is, both the upper surface 91 and the lower surface 92 are arranged in water W to perform plasma cutting of the upper surface 91, the high temperature immediately after cutting is performed at the portion of the upper surface 91 that has been cut. The metal material will come into direct contact with the low temperature water W. Then, due to quenching, the site may be denatured and the hardness may increase. In addition, the cut surface 91c of the upper surface 91 may be roughened by the convection or wave motion of the water W, and the smoothness of the cut surface 91c may decrease. On the other hand, by arranging the upper surface 91 outside the water W, it is possible to prevent these situations from occurring due to contact with the water W. That is, on the upper surface 91, it is possible to avoid hardening due to quenching and roughness of the cut surface 91c due to contact with water W. Even if the inner side surface 91b of the upper surface 91 is in contact with the water W, if the portion above the inner side surface 91b to be the cut surface 91c is arranged outside the water W, those situations can be maintained at a certain level. It can be avoided. However, as described above, by arranging the upper surface 91 completely above the water surface W1 including the inner side surface 91b so that the inner side surface 91b does not come into contact with the water W, the cut portion is particularly effective. Can avoid hardening and roughening. In particular, if the water level is set so that the distance from the inner side surface 91b of the upper surface 91 to the water surface W1 is 50 to 100% of the plate thickness of the metal material constituting the axle housing main body material 90, the inner side surface 91b Due to the effect of the voids between the water surface W1 and the water surface W1, smoothing of the cut surface 91c can be effectively achieved together with reduction of deposits on the lower surface 92b.

Further, by arranging a part of the axle housing main body material 90 in water and performing cutting, it is possible to obtain an effect that the deformation of the main body material 90 due to cutting is suppressed by cooling with water W. In a metal member manufactured through press molding, such as the main body material 90 of an axle housing, stress is accumulated during press molding, but stress is released by heating accompanying cutting, and the metal member has a thickness (upper surface). Deformation such as change (distance between 91) and lower surface 92), warpage, bending, etc. may occur. However, by performing cutting while cooling with water W, deformation due to stress release can be suppressed. As a result, the pair of main body materials 90 and 90 after cutting are butted and welded at the new longitudinal end edges 91d and 92d, and when the axle housing is constructed, the butting and welding can be performed with high accuracy. ..

In addition, by cutting underwater, the efficiency of the entire cutting work and the working environment can be improved. First, since the dust (fume) generated during plasma cutting dissolves in water without being dispersed in the atmosphere, the workability of cutting is improved. Further, since the metal material M1 melted down during cutting is rapidly cooled to form a granular solidified material M3 and precipitates, the waste derived from the melted down metal material M1 can be relatively easily removed by filtration or suction of water W. Can be collected in. Further, in plasma cutting in the atmosphere, a large amount of nitrogen oxides (NOx) are generated, but the generation rate can be reduced by cutting near water W.

The cutting means is not limited to the form of plasma cutting using the plasma cutting torch 10 as the cutting means, and the cutting means capable of applying heat to a part of the plate-shaped metal material and cutting the metal material in the part of the plate-shaped metal material. Other forms can be applied as long as it is a cutting method using. Examples of other forms of cutting methods include a thermal cutting method using a flame, a laser cutting method using a laser beam, and the like, such as gas cutting.

However, the plasma cutting method can perform cutting with high accuracy as compared with the case of using a flame, and can obtain a sharp cut surface 91c with high smoothness. In addition, cutting can be performed at high speed. On the other hand, the plasma cutting method can perform cutting with high accuracy and high speed by using simple and inexpensive equipment as compared with the laser cutting method. From these viewpoints, it is preferable to use the plasma cutting method.

In particular, when plasma cutting is performed using oxygen as the operating gas, it is possible to perform high-speed cutting even on a thick metal material having a plate thickness of more than 10 mm. In the form described above, the axle housing main body material 90 is applied as the work to be cut, but since the axle housing main body material 90 is a constituent member of a vehicle such as a truck, high strength is required. .. Therefore, it has a large plate thickness of about 7 to 22 mm. By performing plasma cutting using oxygen as an operating gas, it is possible to efficiently cut the main body material 90 having such a large plate thickness. Further, as described above, the pair of main body materials 90, 90 having been cut at the longitudinal end edges 91a, 92a are butted against each other at the new longitudinal edge 91d, 92d and fixed by welding, but plasma. By cutting, the new longitudinal edge edges 91d and 92d are formed with excellent shape accuracy and a smooth and sharp cut surface (91c and the corresponding cut surface of the lower surface) for butt and welding. The accuracy can be improved. As a result, it is possible to obtain an axle housing having high shape accuracy and high strength of the welded portion through welding.

As described above, the plasma cutting method has advantages over the thermal cutting method using a flame and the laser cutting method, but the plasma arc A is ejected from the plasma cutting torch 10 with a strong force to perform cutting. Plasma arc A and molten high-temperature metal material M1 are often ejected on the back side of the surface with vigorous force. In particular, when oxygen is used as the operating gas, the energy density of the plasma arc A becomes high, so that these phenomena become remarkable. Therefore, in the plasma cutting method, the influence on the lower surface 92 tends to be larger during the cutting of the upper surface 91 than in the thermal cutting method using a flame or the laser cutting method. However, in the present embodiment, as described above, the upper surface 91 is cut with the lower surface 92 placed in water, and the cooling effect of the water W affects the lower surface 92 that may occur during plasma cutting. Can be effectively suppressed.

In the above embodiment, the plasma cutting torch 10 is automatically moved with respect to the main body material 90 by using the NC device 20 in a state where the axle housing main body material 90 which is a work is fixed, and the longitudinal end edge 91a is used. , 92a is cut along the entire area. The form is not limited to such a form, and may be a form in which the plasma cutting torch 10 is manually moved, or conversely, a form in which the work is moved with respect to the plasma cutting torch 10. However, by moving the plasma cutting torch 10, it is possible to cut a large work such as the axle housing main body 90, and to cut over a long region such as the longitudinal end edges 91a and 92a. It can be easily applied to cutting into relatively complicated shapes. In particular, by controlling the position of the plasma cutting torch 10 using the NC device 20, cutting can be performed with high accuracy.

In this case, as shown in a later embodiment, the upper surface 91 to be cut and the upper surface 91 to be cut by appropriately adjusting the moving speed of the plasma cutting torch 10 together with the energy density of the plasma arc A emitted from the plasma cutting torch 10. It is possible to improve the smoothness of both the lower surface 92 waiting in water. As a result, in the obtained product, it is possible to improve the quality such as the smoothness of the surface constituting the product and the accuracy of the processed shape.

In the axle housing main body material 90, cutting is continuously performed from the start end edge 93 to the end edge 94, and the cut piece 95 including the surplus portion is separated. When cutting continuously up to one site, it is necessary to continue cutting stably from the cut at the initial stage of cutting to the cut through at the end of cutting. Usually, in plasma cutting, when cutting is started from a portion in the surface of a metal material, piercing for forming a through hole is performed using a pilot arc, and cutting is often started from that as a starting point. However, when starting cutting from the starting edge 93, which is the end of the surface of the metal material, it is necessary to cut from the part where the metal material does not exist to the part where the metal material exists, and it is stable from the piercing as the starting point. It is difficult to initiate a cut. In order to stably start cutting under such difficult conditions, as described above, the plasma cutting torch 10 is started to be moved at a low speed while emitting a pilot arc on the outside of the main body material 90. Then, the pilot arc sufficiently close to the main body material 90 is switched to the main arc, and immediately after the increase in the current value is detected, the moving speed of the plasma cutting torch 10 is controlled to increase, so that it is stable from the beginning of cutting. Cutting can be performed under the specified conditions. Further, by appropriately using the pilot arc, it is possible to prevent the electrodes of the plasma cutting torch 10 from being unnecessarily consumed before the cutting is started.

On the other hand, at the end of cutting, when the current value flowing between the plasma cutting torch 10 and the main body material 90 starts to decrease after the cutting reaches the end edge 94, the plasma cutting is performed before the current value becomes completely zero. By stopping the emission of the plasma arc A from the torch 10, cutting can be stably completed. As a plasma cutting torch, a torch is often used in which an abnormality is detected when the current value gradually decreases and reaches zero or its vicinity. In such a case, an abnormality occurs due to the decrease in the current value. It is possible to avoid taking measures such as an emergency stop when the plasma cutting torch 10 is detected, and to stably stop the operation of the plasma cutting torch 10 after cutting through the terminal edge 94 to end the cutting. The specific current value when the operation of the plasma cutting torch 10 is stopped may be set to a value higher than the threshold value at which an abnormality is detected.

In the above embodiment, the cutting device 1 includes a holding jig 30 capable of holding a pair of main body materials 90 and 90, and a pair of plasma cutting torches 10 and 10, and a pair of main body materials 90. 90 cuttings can be performed at the same time. In this way, by configuring the plurality of cutting means to simultaneously cut a plurality of works held by the common holding means, a large number of works can be cut as compared with the case where only one work is cut at a time. It is possible to efficiently cut an individual. In particular, when one product is composed of a pair of workpieces such as the axle housing body material 90, the process of manufacturing a pair of workpieces from a common raw material or cutting by simultaneously performing a pair of cuttings. It becomes easy to secure continuity with the previous and next processes such as the process of joining a pair of later workpieces.

Further, using a holding means capable of changing the arrangement of the work, as in the holding jig 30 of the above embodiment, the first plate-shaped portion 91 is set as the target portion with the change in the arrangement of the work sandwiched between them. The first step of cutting the first plate-shaped portion 91 with the plate-shaped portion 92 as the standby portion, the second plate-shaped portion 92 as the target portion, and the first plate-shaped portion 91 as the standby portion. If the second step of cutting the second plate-shaped portion 92 can be continuously performed in sequence, both the first plate-shaped portion 91 and the second plate-shaped portion 92 can be formed. On the other hand, the processing for cutting can be efficiently advanced. In particular, when cutting two plate-shaped portions having substantially the same shape, such as the upper surface 91 and the lower surface 92 of the axle housing main body material 90, into the same shape, basically the same process is repeated. As a result, both sides can be cut, so that highly efficient cutting can be performed using a simple device configuration and control mode.

[Supporting the holding jig on the side wall of the water tank and preventing water leakage]
Here, in the cutting device 1, the configuration of the support portion that supports the central shaft 31 of the holding jig 30 on the side walls 41a and 41b of the water tank 40, and the water W stored in the water tank 40 from the support portion. The configuration of the seal portion 70 for preventing leakage will be described. FIGS. 7 and 8 show the configurations of the support portion and the seal portion 70 provided on the side wall 41a. Here, of the two ends of the central shaft 31, the end portion on the side where the servomotor 63 or the like is provided is supported by the side wall 41a, and the seal portion 70 is provided on the support portion. The same structure of the support portion and the seal portion 70 can be applied to the portion where the end portion is supported by the side wall 41b.

The side wall 41a of the water tank 40 is provided with a notch 43 for supporting the central shaft 31 of the holding jig 30. The cutout portion 43 is composed of a region in which the plate material constituting the side wall 41a is removed in a substantially rectangular shape. The cutout portion 43 has an opening portion 43a at the upper end thereof, and is open at the upper end edge 41a1 of the side wall 41a. The width (dimension along the upper end edge 41a1 of the side wall 41a) and depth (dimension along the height direction of the water tank 40) of the notch 43 including the opening 43a are the central axis of the holding jig 30. It is set to be larger than the outer diameter of 31 with a margin, and the central shaft 31 can be penetrated through the notch 43 and accommodated. Further, the central shaft 31 can enter and exit the cutout portion 43 via the opening portion 43a.

In a state where the holding jig 30 is attached to the water tank 40, the central shaft 31 is housed in the notch portion 43 in a state of penetrating the notch portion 43. The tip end portion of the central shaft 31 is in a state of projecting from the notch portion 43 to the outside of the side wall 41a. The tip portion thereof is supported by the side wall 41a so as to be axially rotatable via the bearing 61.

A mounting base 44 is fixed to the outer periphery of the notch 43 on the outer surface 41a2 of the side wall 41a. The mounting base 44 serves as a pedestal for fixing the rubber plate packing 71 and the packing case 72 of the seal portion 70, which will be described later, and has a U-shape with an open upper end side. Further, it has a plurality of fixing screw holes 44a for fixing the rubber plate packing 71 and the packing case 72. The mounting base 44 can be installed, for example, by welding a U-shaped plate material to the outer surface 41a2 of the side wall 41a.

The seal portion 70 is provided on the tip end side of the central shaft 31 projecting out of the side wall 41a through the notch 43, and serves to prevent water leakage from the notch 43 between the side wall 41a and the bearing 61. Fulfill. The seal portion 70 has a rubber plate packing 71, a packing case 72, three gland packings 73, 74, 75, and a packing retainer 76 in order from the member attached to the side wall 41a side.

The rubber plate packing 71 is for preventing water W from leaking from between the packing case 72 and the mounting base 44 of the water tank side wall 41a, and is formed of a rubber plate. The rubber plate packing 71 has a U-shape with an open upper end side, which is substantially the same as the mounting base 44. A fixing through hole 71a is provided at a position corresponding to the fixing screw hole 44a of the mounting base 44.

The packing case 72 accommodates the gland packings 73, 74, and 75 and positions them with respect to the central axis 31 of the holding jig 30. The packing case 72 integrally has a bottomed cylindrical packing accommodating portion 72a and a flange portion 72b provided so as to surround the outer edge of the opening of the packing accommodating portion 72a. The inner diameter of the packing accommodating portion 72a is set so as to accommodate the ring-shaped gland packings 73, 74, 75. Further, the bottom portion 72a1 of the packing accommodating portion 72a is provided with a shaft insertion hole 72c as a through hole through which the central shaft 31 of the holding jig 30 can be inserted. The flange portion 72b has a substantially square outer shape, and has a fixing through hole in the vicinity of the outer edge at a position corresponding to the fixing screw hole 44a of the mounting base 44 and the fixing through hole 71a of the rubber plate packing 71. 72d is provided. Further, a plurality of holding screw holes 72e are provided so as to surround the end edge of the packing accommodating portion 72a.

The gland packings 73, 74, and 75 function as a sealing member for suppressing the leakage of water W from the water tank 40 from between the central shaft 31 of the holding jig 30 and the side wall 41a. The gland packings 73, 74, 75 are configured as a string-like material, that is, a flexible long member, and the length thereof is along the outer circumference of the central shaft 31 of the holding jig 30. When the central shaft 31 is surrounded in an annular shape over one round, both end edges are butted against each other with no surplus and almost no shortage. Three gland packings 73, 74, and 75 are used here, but the number thereof is not particularly limited. Further, the materials constituting the gland packings 73, 74, and 75 are not particularly limited, but examples thereof include a braid made of a fiber material impregnated with a lubricant such as oil in which graphite is dispersed. be able to. A constituent material of such a gland packing is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-97719.

The packing retainer 76 is formed by dividing the annular body into a plurality of parts in the circumferential direction thereof. Here, the annular body is composed of two half-split bodies 76a and 76a divided into two. Each half-split body 76a integrally includes a pressing portion 76b having a shape obtained by dividing a small-diameter annulus into two, and a flange portion 76c having a shape obtained by dividing an annulus having a larger outer diameter than the pressing portion 76b into two. Have. The pressing portion 76b can enter the packing accommodating portion 72a of the packing case 72 and come into contact with and press the group of gland packings 73, 74, 75 accommodated in the packing case 72. The flange portion 76c does not enter the packing case 72 but comes into contact with the surface of the packing case 72. The flange portion 76c has a holding through hole 76d at a position corresponding to the holding screw hole 72e of the packing case 72.

When installing the seal portion 70 on the support portion that supports the central shaft 31 of the holding jig 30 on the side wall 41a of the water tank 40, first, with the central shaft 31 protruding from the side wall 41a, the rubber plate packing 71 and the packing The case 72 is arranged so as to overlap the mounting base 44. At this time, the central shaft 31 is allowed to pass through the shaft insertion hole 72c of the packing case 72. Then, with the positions of the fixing through holes 71a and 72d aligned with the fixing screw holes 44a, the rubber plate packing 71 and the packing case 72 are fixed to the mounting base 44 by the fixing screws 77.

Next, the gland packings 73, 74, and 75 are arranged in the packing accommodating portion 72a of the packing case 72. At this time, in the packing accommodating portion 72a, a central shaft 31 inserted into the shaft insertion hole 72c of the packing accommodating portion 72a exists, and surrounds the outer periphery of the central shaft 31 to surround the gland packings 73, 74, 75. To place. At this time, the gland packings 73, 74, and 75 are arranged while forming a ring shape by abutting both ends of the string-shaped material. The three gland packings 73, 74, and 75 are arranged side by side in a layer along the axial direction of the central axis 31. At this time, the positions of the ring-shaped cuts 73a, 74a, 75a of the gland packings 73, 74, 75, that is, the positions corresponding to the ends of the string-shaped material may be shifted from each other along the circumference of the central axis 31. preferable. In the illustrated form, the positions of the three cuts 73a, 74a, and 75a are offset by about 120 °.

Then, the packing retainer 76 is attached. The pressing portion 76b of each half-split body 76a constituting the packing pressing 76 is brought into the packing accommodating portion 72a of the packing case 72. At this time, the angular position of the half-split body 76a is adjusted so that the position of the pressing through hole 76d matches the position of the pressing screw hole 72e of the packing case 72. Then, by pressing the half-cracked body 76a toward the side wall 41a, the gland packings 73, 74, and 75 are pressed by the pressing portion 76b and compressed. In this state, the half-split body 76a is fixed to the packing case 72 by the holding screw 78. The gland packings 73, 74, 75 and the packing retainer 76 can be attached even when the constituent members of the rotary drive unit 60 such as the servomotor 63 are attached to the tip of the holding jig 30.

In the seal portion 70 having such a configuration, the space between the packing case 72 and the side wall 41a of the water tank 40 is sealed by the rubber plate packing 71, and the space between the packing case 72 and the central shaft 31 of the holding jig 30 is grounded. Sealed by packings 73, 74, 75. As a result, the side wall 41a of the water tank 40 and the central shaft 31 of the holding jig 30 are sealed, and the water W stored in the water tank 40 leaks from the support portion supporting the holding jig 30 by the side wall 41a. Can be suppressed.

Conventionally, in general, the seal member arranged on the outer circumference of the rotating shaft of the shaft rotating member has an annular shape, and in that case, the rotating shaft has nothing connected to the tip of the rotating shaft. It is necessary to insert and remove the annular seal member from the tip side. On the other hand, by using a string-shaped sealing member such as the gland packings 73, 74, 75 used in the cutting device 1 according to the present embodiment, even if it is not from the tip side of the central shaft. The seal member can be removed and attached from the side of the central shaft 31. Further, since the packing retainer 76 is also divided into a plurality of parts in the circumferential direction of the central shaft 31, it can be removed and attached from the side of the central shaft 31. Therefore, with the components of the rotary drive unit 60 such as the bearing 61 and the servomotor 63 still attached to the tip of the central shaft 31, the packing retainer 76 and the gland packings 73, 74, 75 are attached and detached to attach and detach the gland packing. 73, 74, 75 can be exchanged.

In the cutting device 1 according to the present embodiment, plasma cutting is performed on the axle housing main body materials 90 and 90 made of steel, so that the water W stored in the water tank 40 contains fume and metal solidified material generated during plasma cutting. M3 is blending and dispersing. Since the fume and the solidified metal M3 tend to reduce the life of the sealing member used for sealing the central shaft 31 of the holding jig 30, it is necessary to replace the sealing member frequently. However, as described above, the string-shaped gland packings 73, 74, 75 and the split type packing retainer 76 are used so that the gland packings 73, 74, 75 can be replaced with the rotary drive unit 60 attached. Therefore, even if it becomes necessary to replace the gland packings 73, 74, 75 frequently, the replacement can be easily completed. Further, if the constituent members of the rotary drive unit 60 such as the bearing 61 and the servomotor 63 are once removed from the tip of the central shaft 31 and reattached, the attachment position of the holding jig 30 with respect to the water tank 40 and the attachment position before and after that If the posture is liable to change, it becomes difficult to ensure reproducibility in the alignment between the holding jig 30 and the plasma cutting torch 10 and 10. However, since the gland packings 73, 74, and 75 can be replaced without removing the rotary drive unit 60, the problem of reproducibility of alignment caused by the removal of the rotary drive unit 60 is less likely to occur.

In the cutting device 1 according to the present embodiment, not only the gland packings 73, 74, and 75 can be replaced, but also the holding jig 30 can be easily attached to and detached from the water tank 40 for maintenance and the like. When it becomes necessary to remove the holding jig 30 attached to the water tank 40, the packing retainer 76 and the gland packings 73, 74, 75 are removed, and the packing case 72 and the rubber plate packing 71 are removed from the water tank 40. The holding jig 30 may be lifted with the fixing screw 77 fixed to the side wall 41a removed. Since the central shaft 31 is accessible from the opening 43a to the notch 43 provided in the side wall 41a, the holding jig 30 can be separated from the water tank 40 simply by lifting the central shaft 31. .. The components of the rotary drive unit 60, such as the bearing 61 and the servomotor 63, may remain attached to the tip of the central shaft 31. When the holding jig 30 is reattached to the water tank 40 after maintenance and the like, the central shaft 31 is housed in the notch 43 from the opening 43a, the rubber plate packing 71 and the packing case 72 are fixed, and the gland is used. The packings 73, 74, 75 and the packing retainer 76 may be attached in sequence.

As described above, the constituent materials of the gland packings 73, 74, and 75 are not particularly limited, but by using a braid made of a fiber material impregnated with a lubricant, the influence of fume in water and the solidified metal M3 Is relatively difficult to receive, and the frequency of replacement can be suppressed. Further, high lubricity can be obtained in the shaft rotation of the holding jig 30.

By arranging a plurality of gland packings 73, 74, 75 along the axial direction of the central shaft 31, higher sealing performance can be exhibited as compared with the case where only one is used. In particular, by shifting the positions of the ring-shaped cuts 73a, 74a, 75a from each other along the circumferential direction of the central axis 31, the water W passes through the cuts 73a, 74a, 75a of the seal portion 70. The possibility of leaking to the outside can be kept low.

Examples of the present invention are shown below. The present invention is not limited to these examples.

[1] Evaluation of deformation due to cutting The degree of deformation that occurs in the work due to stress release due to heating during plasma cutting was evaluated.

[Test method]
As shown in FIG. 9, the axle housing main body material was prepared by press molding, and the surplus portion of the longitudinal end edge thereof was cut by a plasma cutting method. The plate thickness of the steel material constituting the main body material was 7 mm.

Plasma cutting was performed under three conditions: atmospheric, semi-water, and total water. When cutting in the air, the cutting was performed with the main body material placed on a slatted table. When cutting in semi-water or full-water, the cutting was performed with the main body material held in a water tank in which water was stored. In the case of semi-water, the main body material was made to exist in the water up to the central position between the upper surface and the lower surface. In the case of all water, the inner surface of the upper surface is in contact with the water surface, that is, the lower surface is in the water and the upper surface is in contact with the water surface on the inner surface and is outside the water.

For cutting, a plasma cutting torch (manufactured by Komatsu) using oxygen as an operating gas was used. The cutting conditions were an output of 200 A, a nozzle diameter of φ2.2 mm, a cutting speed (torch moving speed) of 3 m / min, and a torch height of 4 to 5 mm at the time of cutting.

Before and after cutting, the width, warpage, and bending parameters of the main body material were measured. As shown in FIG. 9, the width P1 was measured with a caliper as a distance between the outer surface of the upper surface and the outer surface of the lower surface of the main body material. The measurements were made at multiple points on the top and bottom of the axle housing and the maximum displacement from the design dimensions was recorded. The warp P2 was measured using a three-dimensional measuring machine as a deviation from the plane of the surface of the plate material. At this time, the maximum value of the displacement amount at a plurality of points on the upper surface and the lower surface was recorded with reference to the central position in the longitudinal direction x of the axle housing. The bending P3 was measured using a height gauge as a deviation from the linear shape along the longitudinal direction x of the main body material. At this time, the maximum value of the displacement amount at a plurality of points on the upper surface and the lower surface and the inclination angle of the end edge in the longitudinal direction were measured and recorded after cutting with reference to the straight line connecting both ends in the longitudinal direction.

[result]
Table 1 summarizes the measurement results of the displacements of width, warpage, and bending under each condition of air, semi-water, and total water.

In Table 1, when the amount of change in width and warpage before and after cutting and the measured value of bending after cutting are compared between each condition, all parameters are more than in semi-water or in semi-water than when cutting in air. The value is small when cutting in all water. This indicates that by arranging at least a part of the work in water for cutting, the effect of cooling can reduce the deformation due to the influence of heat at the time of cutting.

Further, the value of each parameter when cutting in semi-water is about the same as or smaller than that in the case of cutting in full water. This indicates that it is not necessary for the entire work to be placed in water in order to obtain the effect of preventing deformation by cooling, and that the effect can be sufficiently achieved if only about half of the work is placed in water. There is.

[2] Evaluation of the effect of plasma cutting conditions Adjustment of plasma cutting conditions, energy density of plasma arc emitted from plasma cutting torch and cutting speed (speed of moving plasma cutting torch) is the target part and standby after cutting. The effect on the condition of the club was investigated.

[Test method]
The cutting test was carried out under the conditions corresponding to the semi-water of the test of the above [1]. At this time, by changing the flow rate of oxygen gas, the energy density of the plasma arc was changed variously, and the cutting speed was also changed variously. The nozzle diameter of the plasma arc was set to φ2.5 mm and φ3.0 mm.

The quality of the upper surface and the lower surface of the main body material after cutting was evaluated. On the upper and lower surfaces, no dross-like or protruding deposits are formed on the inner surface, or even if they are formed, they are adhered only with a weak force that can be removed by the operator by hand. Was judged to be good. On the other hand, when the deposit was attached with a strong force that could not be easily removed by hand, it was determined to be defective. In the example of FIG. 10, a protrusion-like deposit M2 that cannot be easily removed is formed on the upper surface and is determined to be defective, but on the lower surface, no deposit is confirmed and it is determined to be good. When both the upper surface and the lower surface can be determined to be good, it is determined that the cutting condition is good, and when it is determined that either the upper surface or the lower surface is defective, it is determined that the cutting condition is defective.

In FIG. 11, when the cutting speed is on the horizontal axis and the energy density is on the vertical axis, and the cutting conditions are judged to be good in each combination, “○” (nozzle diameter φ2.5 mm) and “●” (nozzle diameter φ3.0 mm) are shown. ), And the case where it is judged that the cutting condition is bad is indicated by "x". Looking at the results, as shown by the broken line, the points where the cutting conditions are good are gathered in the region where the energy density is about 41 to 56 A / mm ² . This result shows that by appropriately adjusting the energy density and cutting speed, good finish quality with less deposits and high smoothness can be obtained on both the upper surface as the target portion and the lower surface as the standby portion. ing.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

1 Cutting device 10 Plasma cutting torch (cutting means)
20 NC device 30 Holding jig (holding means)
31 Central axis (shaft part)
40 Water tank (liquid refrigerant storage means)
41 (41a, 41b) Side wall 43 Notch 44 Mounting base 50 Conveyor (conveying means)
60 Rotation drive unit 61, 64 Bearing 62 Coupling 63 Servo motor 70 Seal unit 71 Rubber plate packing 72 Packing case 73, 74, 75 Gland packing (seal member)
76 Packing retainer (pressing member)
90 (Axle housing) Main body material 91 Top surface (first plate-shaped part)
92 Bottom surface (second plate-shaped part)
91a, 92a Longitudinal edge 91b, 92b Inner surface 91c Cut surface 91d, 92d New longitudinal edge 93 Start edge 94 End edge 95 Cut piece A Plasma arc M1 Melted metal material M2 Adhesion M3 Granular solidified W Water (liquid refrigerant)
W1 water surface

Claims (16)

A cutting means for applying heat to a part of a plate-shaped metal material to cut the metal material in the part, and
A liquid storage means for storing liquid refrigerant and
In a cutting device having a holding means for holding an object to be cut made of a metal material in a position where it can be cut by the cutting means in the liquid storage means.
The holding means has a shaft portion that is rotatably supported by the side wall in a state where the tip portion is projected to the outside of the side wall of the liquid storage means.
The cutting device is further made of a string-like material and is arranged on the outside of the side wall so as to surround the outer periphery of the shaft portion to prevent the liquid refrigerant from leaking from between the shaft portion and the side wall portion. Members and
A cutting device comprising, from the outside of the side wall, a seal holding member that can be divided into a plurality of parts in the circumferential direction of the shaft portion, which presses the seal member against the side wall. The cutting device has a transport means in the liquid storage means.
The first aspect of the present invention is characterized in that the transport means transports the cut pieces separated in the liquid refrigerant when the object to be cut is cut by the cutting means to the outside of the liquid storage means. The cutting device described. A plurality of the sealing members are provided along the axial direction of the shaft portion, and the positions of the ends of the string-shaped materials constituting each sealing member are offset from each other along the circumference of the shaft portion. The cutting device according to claim 1 or 2. The side wall is provided with a notch that is open at the upper end edge of the side wall.
The shaft member is supported in a state of being housed in the notch portion, and can enter and exit the notch portion through an opening provided at the upper end edge of the side wall. The cutting device according to any one of claims 1 to 3, wherein the cutting device is characterized. The cutting device according to any one of claims 1 to 4, wherein the string-shaped material constituting the sealing member is made of a braided body made of a fiber material impregnated with a lubricant. The cutting device according to any one of claims 1 to 5, wherein the cutting means is a plasma cutting torch. The cutting device according to claim 6, wherein the plasma cutting torch uses oxygen as an operating gas. Using the cutting device according to any one of claims 1 to 7, the first plate-shaped portion is made of a metal material, and the first plate-shaped portion is separated from the first plate-shaped portion. In a cutting method for cutting an object to be cut having a second plate-shaped portion facing the surface.
Of the first plate-shaped portion and the second plate-shaped portion, one is a target portion and the other is a standby portion.
A cutting method characterized by arranging the standby portion in a liquid refrigerant and cutting the target portion in a state where the target portion is arranged outside the liquid refrigerant. The cutting method according to claim 8, wherein the surface of the target portion facing the standby portion is arranged so as not to come into contact with the liquid refrigerant. The cutting method according to claim 8 or 9, wherein the object to be cut is cut while the cutting means is moved with respect to the object to be cut while the object to be cut is fixed. The cutting means is a plasma cutting torch.
When cutting the target portion while moving the cutting means along the surface of the target portion, starting from the starting end edge which is one part of the end edge of the target portion.
With the cutting means arranged outside the starting edge and the plasma arc emitted from the cutting means, the cutting means is moved toward the starting edge and flows between the cutting means and the object to be cut. The cutting method according to any one of claims 8 to 10, wherein when the current value starts to increase, the moving speed of the cutting means is increased. The cutting means is a plasma cutting torch.
While moving the cutting means along the surface of the target portion, when cutting the target portion with the end edge, which is one part of the end edge of the target portion, as an end point.
When the current value flowing between the cutting means and the object to be cut begins to decrease after the cutting by the cutting means reaches the terminal edge, the plasma arc from the cutting means is performed before the current value becomes zero. The cutting method according to any one of claims 8 to 11, wherein the emission of the current is stopped. When the target portion is cut by the cutting means, the energy density of the heat given to the object to be cut by the cutting means and the cutting means are described so that the smoothness of the target portion and the standby portion is increased. The invention according to any one of claims 8 to 12, wherein at least one of the moving speed of the cutting means when cutting the object to be cut while moving the object to be cut is adjusted. How to cut. The first step of cutting the first plate-shaped portion by using the first plate-shaped portion as the target portion and the second plate-shaped portion as the standby portion.
Of the second step of cutting the second plate-shaped portion with the second plate-shaped portion as the target portion and the first plate-shaped portion as the standby portion.
The cutting method according to any one of claims 8 to 13, wherein after performing one step, the arrangement of the object to be cut is changed and the other step is performed. The cutting method according to any one of claims 8 to 14, wherein a plurality of cutting means are used to simultaneously cut a plurality of objects to be cut held by a common holding means. The object to be cut is a pair of metal members having a first plate-shaped portion and a second plate-shaped portion in a bending portion formed by bending a plate material into a U-shaped cross section.
The cutting means is used to cut the surplus wall at the edge of the bent portion of the pair of metal members, and then the pair of metal members are abutted against each other and fixed at the edge. The cutting method according to any one of claims 8 to 15.

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