JPH0672252B2 - How to insert a circular saw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for forming a circular saw material having a disk shape in a circular saw manufacturing process.

b. Conventional technology In general, when a force is applied to a material, a certain amount of deformation occurs, but when the applied force is gradually increased, the amount of deformation correspondingly increases.
However, depending on the shape of the material and how the force is applied, when the applied force reaches a certain level, a phenomenon in which the deformation suddenly shifts to a completely different deformation from the previous deformation, that is, a buckling phenomenon occurs.

In the case of a circular saw, the buckling phenomenon described above may occur due to thermal stress. The mechanism of this buckling phenomenon is as follows.

That is, frictional heat is generated in the outer peripheral portion of the circular saw when the circular saw is used to rotationally cut an object to be cut such as wood and wood materials (including plastic). Since frictional heat is not generated at all, a relatively large temperature gradient is generated between the outer peripheral portion and the inner peripheral portion of the circular saw. Then, due to the frictional heat generated in the outer peripheral portion, the portion in the vicinity of the blade portion of the circular saw tries to extend in the outer peripheral portion, but it cannot extend due to the resistance of the inner peripheral portion, so that a tensile force is applied to the inner peripheral portion, As a reaction thereof, a compressive stress is generated on the outer peripheral portion. Therefore, the rate of expansion between the outer peripheral portion and the inner peripheral portion of the circular saw is greatly different, and as the outer peripheral portion expands, compressive stress is generated in the outer peripheral portion and tensile stress is generated in the inner peripheral portion. A stress gradient is created between the outer circumference and the inner circumference of the circular saw.

When the thermal stress becomes large and the outer peripheral part of the circular saw rises to a certain temperature, what has been expanded and contracted in the plane until then suddenly changes to another type (for example, as shown in Figs. 9 and 10). The circular saw a is dented like a plate or is deformed into a wavy shape. If such deformation or buckling occurs, the circular saw will no longer be able to cut, which will interfere with the cutting work.

Therefore, in order to prevent the occurrence of buckling due to frictional heat as described above, the circular saw material is subjected to waist insertion processing.
This waist insertion process is performed by subjecting a suitable circular ring portion of the circular saw material to plastic expansion processing, whereby a tensile internal force is applied in the circumferential direction at the outer peripheral portion of the saw blade and saw stress is generated as thermal stress during cutting. The tangential compressive stress generated in the outer peripheral portion of the blade is canceled, and buckling is effectively prevented.

As this type of waist insertion method, a hammer striking method in which a worker hits the plate surface of a circular saw material with a hammer to perform plastic expansion processing, or a metal roller is applied to both sides of the circular saw material, respectively. Hold the pair of metal rollers firmly
A roller processing method of pressing and performing plastic expansion processing has been conventionally performed.

c. Problems to be Solved by the Invention However, the conventional hammering method and roller pressing method, which are the conventional hip insertion methods, have the following major problems.

First of all, in the case of the hammering method, a great deal of intuition and knack are required for the work of hitting a circular saw material with a hammer to perform plastic expansion processing on a predetermined waist insertion part, especially on the entire processed surface. Since it requires many years of experience and skill to obtain uniform lumbar strength, it was difficult to save labor and automate the manufacturing process of the circular saw. In addition, even a sufficiently skilled person has a very poor workability and it is difficult to obtain a homogeneous product, so that it is not possible to mass-produce a good-quality circular saw at a low price.

Next, in the case of the roller pressing method, it does not require intuition or tips as compared with the hammer hitting method, but when performing plastic expansion processing on the waist insertion part using a metal roller, preprocessing (circular saw material Of rotary grinding for manufacturing) is likely to be affected, and local strength of hip insertion is likely to occur. Therefore,
In many cases, the lumbar insertion strength becomes non-uniform over the entire surface to be machined. In such a case, the roller pressure was repeatedly applied repeatedly, or the hammering method described above was used together. . For this reason, there are major problems that the production efficiency is extremely low and that it is difficult to obtain a uniform waist strength under certain processing conditions.

The present invention has been made in view of the actual situation as described above, and an object thereof is to efficiently and flexibly deform a circular saw without requiring skill such as intuition or tips. It is an object of the present invention to provide a chining method that can perform strong chining without causing any labor, and that can save labor and can be automated.

d. Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, in the waist insertion method performed in the manufacturing process of the circular saw, the center portion and the outer peripheral portion of the circular saw material having a disc shape are formed. Shot grains are located only in a plurality of scattered locations arranged at equal intervals along a radial direction and a circumferential direction of the circular saw material, which are locations within a circular area on the inner diameter side from a predetermined location between the locations. By performing the shot peening process by projecting, a compressive stress is generated in the shot peening process positions adjacent in the radial direction of the annular region, and a compressive stress larger than the compressive stress between these shot peening process positions. In response to this, a tensile internal force along the circumferential direction is applied to the region on the outer peripheral side of the annular region.

Further, according to the present invention, in the waist insertion method performed in the manufacturing process of the circular saw, it is a position within a circular ring region on the inner diameter side from a predetermined position between the central portion and the outer peripheral portion of the disc-shaped circular saw material. hand,
And shot peening by projecting shot grains only to a large number of scattered points radially extending along the radial direction of the circular saw material in a region arranged at equal angular intervals along the circumferential direction of the circular saw material. By performing the processing, while generating a compressive stress in the shot peening processing locations adjacent to the diameter direction of the annular region, to generate a larger compressive stress than the compression stress between these shot peening processing locations, Accordingly, the tensile internal force along the circumferential direction is applied to the region on the outer peripheral side of the annular region.

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a shot peening apparatus 1 for carrying out a waist insertion method according to the present invention.
Is a holding jig 3 for holding a circular saw blank 2 which is a workpiece, and a drive mechanism 4 for rotationally driving the holding jig 3.
And a device body 6 including a shot grain projection mechanism 5.

The apparatus main body 6 described above is provided with a vertical robust housing 9 having chambers 8a, 8b divided into upper and lower stages, and a holding mechanism 3 is arranged on a partition wall 10 of the housing 9, In relation to the mechanism 3, the drive mechanism 4 is arranged in the chamber 8b below the housing 9. The drive mechanism 4 includes an induction motor 14 that applies a rotational force to a drive shaft 13 via a rotational force transmission mechanism 12 including a belt and a pulley, and the drive shaft 13 is a bearing portion 15 of the holding mechanism 3.
The inside is rotatably inserted, and the tip thereof is connected to the workpiece holding base 16.

As shown in FIGS. 1 to 3, the above-mentioned holding jig 3 is provided with a base 16, a mask member 17a vertically fixed on the base 16, and a mask member 17a facing the mask member 17a. And a ring-shaped intervening member 18 arranged between the mask members 17a and 17b.
The above-mentioned mask members 17a, 17b are formed into a disc shape,
A circular hole 17c corresponding to the central hole 2a of the circular saw blank 2 is provided at the center of each of them. Further, a large number of circular openings 19a, 19b are regularly formed in the mask members 17a, 17b. That is, as clearly shown in FIG. 2, the mask member 17a
In a circular region A on the inner diameter side from a predetermined position between the central portion and the outer peripheral portion of the circular openings 19a, circular openings 19a having the same diameter are arranged at equal intervals along a line extending radially in the radial direction at equal angular intervals. Punching is performed in this state, and therefore circular apertures 19 are also arranged at equal intervals along the circumferential direction of a predetermined diameter. On the other hand, circular openings 19b are also formed in the mask member 17b in the same arrangement.

On the side wall 20 of the chamber 8a above the housing 9, the shot grain projection mechanism 5 described above is arranged. The shot grain projection mechanism 5 of this example is of a centrifugal force type and is provided with a shot grain supply source 21, a shot grain supply pipe 22, a pipe 22 connected to the pipe 22, and a side wall 20 of the housing 9 penetratingly arranged. It comprises a horn-shaped member 23, an impeller 24 rotatably arranged in the horn-shaped member 23, and a motor 25 for rotationally driving the impeller 24 in a vertical plane. In addition, as the above-mentioned impeller 24, one having a diameter of 400 mm and eight blades is used, and 1500 r.
It is driven to rotate at a rotational speed of pm, which allows for example a diameter of 0.
Shot particles (steel balls) of 5 to 1.2 mm are projected into the chamber 8a at a speed of 50 to 60 m / s.

Further, a shot grain discharging hole 28 is formed at an outer edge portion of the partition wall 10 of the housing 9, and a chamber of the housing 9 is formed.
A shot grain guide wall 30 is provided near the inside of the side wall 29 of 8b, and a passage 31 is formed by the side wall 29 and the guide wall 30. At the lower end of the passage 31, a shot particle suction pipe 32 is provided.
Is connected to one end of the tube 32, and the other end of the tube 32 is connected to a separator 33 arranged above the housing 9.
The separator 33 is for separating and ejecting shot particles that have been damaged to the extent that they cannot be reused out of the shot particles that have been projected. Shot grain supply through 21
To be fed back to. Further, a dust collecting device 36 is connected to the horn-shaped member 23 of the shot grain projection mechanism 5 via a suction pipe 35.

Next, a description will be given of the case where the circular saw blank 2 is subjected to waist insertion processing using the shot peening apparatus 1 having the above-described configuration.

First, the circular saw blank 2 obtained by performing the quenching and tempering process is attached to the holding jig 3 of the apparatus main body 6 as shown in FIG. 1 to hold the circular saw blank 2 vertically.
To attach the circular saw material 2 to the holding jig 3, the outer peripheral edge of the circular saw material 2 is applied so as to be coaxial with the mask member 17a, and the other mask member 17b is circularly attached. A ring-shaped interposing member that is coaxially applied to the outer peripheral edge of the other surface of the saw material 2 and is disposed between the pair of mask members 17a and 17b on the outer peripheral edge of the circular saw material 2 and on the outer peripheral side thereof. 18 is sandwiched together, and under this condition, the mask members 17a, 17b are bolts 38 and nuts 39 at several points on the outer peripheral edge and in the center.
It is performed by tightening and fixing with (Fig. 2 and 3
See figure). As a result, the circular saw material 2 becomes a pair of mask members.
It is firmly held between 17a and 17b, and circular saw material 2
Both surfaces are masked except for the portions corresponding to the circular openings 19a and 19b.

Then, the circular saw material 2 is attached to the holding jig 3 in a state where only the portion corresponding to the circular opening 19 is exposed, and, as shown in FIG. 3, each circular shape of the pair of mask members 17a and 17b. The apertures 19 are fixed in a state of being arranged to face each other.

In this way, after attaching the circular saw material 2 to the holding jig 3, by operating the induction motor 14,
The holding jig 3 and the circular saw blank 2 are driven to rotate in the direction of arrow S in FIG. Next, the shot grain supply source 21 to the supply pipe 22
Supply a large number of shot particles into the horn member 23 via
The impeller 24, which is rotationally driven at a high speed by the motor 25, projects shot particles toward the circular saw blank 2 to subject the portion B corresponding to the circular opening 19 to plastic working. At this time, the portion B of the circular saw material 2 corresponding to the circular opening 19
Since the other parts are completely masked as described above, no plastic working is performed.

As described above, shot particles are projected for a predetermined period of time to complete the hip insertion process on the circular region of the circular saw blank 2, and then the shot particles are stopped.

The shot particles that have been projected fall through the holes 28 of the partition wall 10 in the passage 31 of the lower chamber 8b and are transferred to the separator 33 via the shot particle suction pipe 32, and only reusable crushed particles are provided. The separated shot grains are discharged to the outside, and the reusable shot grains are supplied again to the shot grain supply source 21 for reuse.

Next, using the shot peening apparatus 1 as described above,
A specific example of carrying out the waist insertion method according to the present invention is shown below.

Example 1 (1) Material of circular saw material SKS-5 (2) Dimensions of circular saw material Outer diameter 305mm Center hole diameter 25.4mm Plate thickness 2.4mm Number of teeth 79 (3) Circular area A Circular saw material 2 35-89 mm strip from the outer circumference (4) Diameter of mask members 17a and 17b 10 mm (5) Arrangement angle of circular openings of mask member θ (See Fig. 2) θ = 12 ° (6) Shot processing part (7) Processing conditions <a> Shot grain diameter 0.8 mm <b> Shot grain hardness HRC58 <c> Shot grain material Cast steel <d> Shot grain projection speed 50 m / s <e> Shot grain projection angle 90 ° <H> Projection time of shot grains 4 minutes <G> Rotational speed of circular saw material 10r.pm The circular saw material obtained in Example 1 had no bending deformation, and the residual stress on its surface was measured. The results are shown in FIG.

As is clear from the measurement results shown in FIG. 6, generation of sufficient compressive stress (negative stress) is recognized in the portion B where the shot grains are projected, that is, the shot peening processed portion B, as indicated by the symbol C. .

Further, the residual stress at the intermediate portion between the shot peening processed portions B which are adjacent to each other along the diametrical direction of the circular saw material 2 is a compressive stress larger than the residual stress of the shot peening processed portions B on both sides, as indicated by a symbol D. Is confirmed to have occurred.

Incidentally, in the usual prediction, a larger compressive stress is generated in the portion that is impacted by the shot grains than in the peripheral portion, and the compressive stress is not generated in the portion that is not shot peened,
On the contrary, it is considered that tensile stress is generated. Contrary to this, the reason why the above phenomenon occurs is as follows. That is, when shot particles are projected onto the shot peening processed portion B which is a large number of scattered spots to give an impact force, the impact force is dispersed around the impact portion (shot peening processed portion B), and this is dispersed. It is considered that the impact forces are combined and synergized at the intermediate points of the impact parts adjacent to each other, and as a result, a large compressive stress is developed.

On the other hand, it is recognized that a tensile internal force (positive stress) is generated in a portion on the outer periphery of the annular region A, as indicated by a symbol E. The broken line in FIG. 6 indicates the residual stress at the intermediate portion between the shot peened portions B adjacent to each other along the circumferential direction of the circular saw material 2. As is clear from this measurement result, a relatively small compressive stress is generated in the annular region A, and the tensile internal force is generated in the outer peripheral region thereof, even though the spot peening process is not applied to the relevant region. Is recognized to have occurred. It should be noted that what is indicated by a chain line in FIG. 6 is the residual stress of the circular saw blank 2 before the shot peening process.

Therefore, it was confirmed that the circular saw material 2 was subjected to ideal waist insertion processing with sufficiently strong waist insertion strength.

That is, even if frictional heat is generated in the outer peripheral portion of the circular saw by the heat generated in the outer peripheral portion in the vicinity of the outermost periphery where the blade is attached and compressive stress is generated inside, the compressive stress generated by the shot peening process Since the tensile stress is previously applied to the outer peripheral portion due to the existence of the annular region provided with, the thermal expansion is performed without exerting a tensile force on the inner diameter portion, and therefore a large stress gradient is not generated. Therefore, the thermal buckling phenomenon of the circular saw can be effectively prevented.

In order to confirm such an effect, after the circular saw material obtained in this example is subjected to rotary grinding and setting, and a tip blade made of cemented carbide or the like is attached to the outermost peripheral portion thereof,
When a cutting test was conducted, no abnormal phenomenon such as thermal buckling occurred, and the durability was similar to that of the conventional hammering method or the roll-pressing method, and good results were obtained. .

4 and 5 show a second embodiment of the present invention, in which the circular openings 19a, 19b of the mask members 17a, 17b closely arranged on both the front and back surfaces of the circular saw blank 2 are mutually adjacent. This is an embodiment in which a state of being shifted without being opposed is shown. More specifically, in this example, the circular opening 19 of one mask member 17a is used.
Of the circular openings 19 of the other mask member 17b so as to correspond to the portion between the circular openings 19 adjacent to each other along the circumferential direction.
Are arranged.

When the residual stress on the surface of the circular saw blank 2 obtained by the method according to this example was measured, the results shown in FIG. 7 were obtained. As is clear from the measurement results shown in FIG. 7, residual stress having a tendency substantially similar to that of the embodiment shown in FIG. 3 is applied, and it is recognized that ideal backing is performed.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the waist insertion strength can be easily adjusted by appropriately changing the processing conditions such as the shot particle projection direction, the projection speed, the projection time, and the grain size material. Further, it is not always necessary to perform the shot peening process while rotating the circular saw material 2, and it may be reversed by 180 ° at a predetermined time, and the circular saw material 2 is stopped.
The shot particles may be projected from both sides. Furthermore, the mask members 17a, 17b have a non-circular shape (square,
You may provide the opening of the shape of an ellipse etc.).

In each of the above-described embodiments, a large number of circular holes 19 for shot peening are provided in the annular portion A of the mask members 17a and 17b, but the present invention is not limited to this and is shown in FIG. As described above, a large number of elongated holes 40 extending in the radial direction may be radially formed in the annular portion A of the mask members 17a and 17b. Also in this case, it was confirmed by experiments that good waisting can be performed as described above.

e. Effect of the Invention As described above, according to the present invention, a large number of scattered points (diameter of circular saw material are provided in a circular area on the inner diameter side from a predetermined location between the center portion and the outer peripheral portion of the circular saw material having a disk shape). Shot peening (plasticity) at locations that are arranged at equal intervals in each direction and in the circumferential direction, or at locations that extend in the radial direction in areas that are arranged at equal angles along the circumferential direction of the circular saw material. By processing), a compressive stress is generated in the circumferential direction (tangential direction) of the annular region, and an internal tensile force along the circumferential direction is applied to the outer peripheral region of the annular region, that is, the outer peripheral portion near the outermost blade portion. Since it is designed to be given,
It is possible to obtain a circular saw that has been subjected to good waist insertion processing with high waist insertion strength. Further, by adjusting the size and material of the shot grains, the projection conditions, etc., the residual stress and hence the strength of the waist insertion can be easily adjusted.

Furthermore, in the present invention, since shot peening only needs to be performed on predetermined scattered spots, the shot area can be small, and distortion of the circular saw material can be prevented even if strong shot peening is performed.

Further, by performing the shot peening process only on a large number of dispersed portions of the predetermined annular region,
Since the compressive stress is generated in the shot peening processing area and the compressive stress larger than the compressive stress is generated in the area between these, the compressive stress is dispersed and the stress concentration can be avoided, and thus the shot peening processing is performed. It is possible to prevent curved deformation of the circular saw material due to the above, and to obtain a flat circular saw product. Moreover, due to the compressive stress characteristics as described above, it is possible to impart impact absorbing ability.

Moreover, according to the method of shot grain projection according to the present invention, it is possible to obtain a uniform waist insertion strength without requiring skill as compared with the conventional hammer striking method, and it is troublesome as in the conventional roll pressing method. It is possible to efficiently perform waist insertion processing with a single operation without performing repeated operations.

Further, a conventionally known shot peening apparatus may be used as an apparatus for carrying out the present method, and therefore, it is possible to automate the waist insertion process and easily save labor.

[Brief description of drawings]

1 to 3 are for explaining a first embodiment of the present invention, and FIG. 1 is a sectional view of a shot peening apparatus for carrying out a waist insertion method according to the present invention. FIG. 3 is a front view of a jig for holding a circular saw material, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIGS. 4 and 5 are for explaining a second embodiment of the present invention. FIG. 4 is a front view of a jig for holding a circular saw material, and FIG. 5 is a front view of FIG.
VV line sectional view, FIG. 6 is a graph showing the measurement results of residual stress when shot grains are projected by the method according to the first embodiment, and FIG. 7 is shot grain is projected by the method according to the second embodiment. FIG. 8 is a graph showing the measurement result of residual stress in the case, FIG. 8 is a front view of a holding jig showing another example of the present invention, FIG. 9 and FIG.
FIG. 10 is a sectional view showing a buckling state of a circular saw. 1 ... Shot peening device, 2 ... Circular saw material, 3 ... Holding jig, 4 ... Drive mechanism, 5 ... Shot grain projection mechanism, 6 ... Device body, 17a, 17b ... Mask member, 19a , 19b ...... Circular aperture, 21 ...... Shot grain supply source, 22 ...... Shot grain supply source, 23 ...... Horn-shaped member, 24 ...... Impeller, 40 ...... Long hole, A ...... Circular saw material 2 Ring area, B ... Shot peening processing part.

Claims (2)

[Claims] 1. In a waist insertion method performed in a circular saw manufacturing process, a portion within a circular territory region on the inner diameter side from a predetermined portion between the central portion and the outer peripheral portion of a disc-shaped circular saw material. And, and
By performing shot peening processing by projecting shot grains only at a large number of scattered points arranged at equal intervals along the radial direction and the circumferential direction of the circular saw material, the circular saw region is adjacent in the radial direction. Along with generating compressive stress in the shot peening processing locations, a compressive stress larger than the compressive stress is generated between these shot peening processing locations, and in response to this, a peripheral area is formed on the outer peripheral side of the annular area. A method for inserting a circular saw into a waist, characterized in that a tensile internal force along the direction is applied. 2. A waist insertion method performed in a circular saw manufacturing process, comprising a portion in a circular ring region on the inner diameter side from a predetermined portion between the central portion and the outer peripheral portion of a disc-shaped circular saw material. ,And,
Shot peening is performed by projecting shot grains only at a large number of scattered points radially extending along the radial direction of the circular saw material in a region arranged at equal angular intervals along the circumferential direction of the circular saw material. By performing a compressive stress at the shot peening processing locations adjacent to the diametrical direction of the annular region, to generate a larger compressive stress than the compressive stress between these shot peening processing locations, according to this. A method for inserting a circular saw into the waist, wherein a tensile internal force along the circumferential direction is applied to an area on the outer peripheral side of the annular area.