JP6737848B2 - Machine Tools - Google Patents

Description

The present invention relates to a machine tool, and more particularly, to a machine tool having a structure in which a ram is arranged on a column.

A so-called vertical machine tool basically has a column standing on a bed (base) and a ram horizontally installed on the column to directly support the machining head. The processing head to which the main spindle is attached is configured to perform processing on a workpiece placed on the table.

In the machine tool having the above-described structure, a structure in which a guide mechanism for guiding the ram horizontally with respect to the column is provided between the column and the ram is a saddle-like member under the table. Compared to the case where the moving body is arranged, the table can be made lower, which has the advantage of improving workability. Further, in the above-described configuration, since the load limitation when the saddle is provided is reduced, the capacity of the processing tank can be increased. Therefore, the above configuration is often adopted in a large machine tool, and in such a case, as a result, the ram tends to be large.

As described above, the structure in which the guide mechanism is provided between the column and the ram needs to support the ram so that the ram can be moved by the guide mechanism, and thus supports the ram as compared with the structure in which the ram is fixed to the column. The strength tends to be low. Therefore, when the ram moves, for example, in the front-rear direction (Y-axis direction), when the ram moves forward, it tilts to the front side and causes a deviation of the moment. As a result, the positioning accuracy in machining is increased as the ram moves. It may decrease, or the entire machine may shake or vibrate.

Conventionally, a machine tool has also been proposed that addresses the above problems. For example, in Patent Document 1, in an electric discharge machine, a screw shaft is screwed onto a ram and a balancer, and the screw shaft is rotated to move the ram and the balancer in mutually opposite directions, thereby generating a moment acting on the ram. The technique that the balancer tries to offset is shown. Further, Patent Document 2 discloses a technique in an electric discharge machine in which a large reinforcing rib is attached to a ram to improve rigidity and prevent the overhang of the ram due to the above-mentioned moment.

JP-A-2-152740 Japanese Patent No. 3837910

However, the techniques disclosed in Patent Documents 1 and 2 described above have problems in that the structure of the machine tool is complicated and that the weight of the ram is increased to easily generate a large moment.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a machine tool capable of preventing a decrease in positioning accuracy due to a moment generated in a ram and the occurrence of vibration.

The machine tool according to the present invention is
A column,
A ram placed above this column,
A guide mechanism that is interposed between the column and the ram and that guides the ram to the column so as to be movable in the front-rear direction,
In a machine tool equipped with
The upper link is rotatably supported on the ram, and the lower link is rotatably supported on the column and the upper link is rotatably connected to the lower link of the upper link. A link mechanism in which two link bodies, in which the upper link and the lower link are opened forward at an angle of less than 180°, are provided with a gap in the front-rear direction,
Of the two link bodies, a front-side link body disposed on the front side in the front-rear direction is applied with a forward force to the connecting portion between the upper link and the lower link, and the front-back direction of the two link bodies. Urging means for applying a force directed rearward to the connecting portion between the upper link and the lower link of the rear link body arranged on the rear side in the direction,
Is provided.

In the machine tool of the present invention, as the urging means, for example, a connecting arm that connects the front link body and the rear link body and is urged by the urging force in the extending direction can be preferably used.

More specifically, the connecting arm as described above is provided between one end connected to the front link body, the other end connected to the rear link body, and the one end and the other end. And a compression spring.

When the above-mentioned connecting arm is applied, one end of the connecting arm is connected to the connecting portion between the upper link and the lower link of the front link body, and the other end of the connecting arm is connected to the rear link body. It is desirable that the upper link and the lower link are connected to each other.

On the other hand, it is desirable that the two link bodies are provided on the left and right outer sides of the column and the ram, respectively. However, the present invention is not limited to this, and the two link bodies may be provided only on the left outer side of the column and the ram, or only on the right outer side.

Since the machine tool according to the present invention has the link mechanism including the front and rear two link bodies provided between the column and the ram, and the biasing means including, for example, a connecting arm, the front link body An upward force acts on the ram from the upper link, and a downward force acts on the ram from the upper link of the rear link body. Therefore, due to these upward and downward forces, the downward moment generated in the ram, which pushes the front side of the ram downward, is canceled out, and the deterioration of the positioning accuracy and the occurrence of vibration due to this moment are prevented. To be done. It should be noted that the above-mentioned "moment is canceled" does not mean that the moments are completely canceled, but means that the downward force that pushes the front side of the ram downward by the moment is reduced. Is.

Side view of a machine tool according to an embodiment of the present invention Diagram for explaining the force that cancels the moment generated in the ram in the machine tool Diagram that models the link mechanism in the above machine tool Graph showing the distribution of force canceling the moment in the above machine tool Graph showing another example of distribution of force that cancels out moment

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a side shape of a machine tool 10 according to an embodiment of the present invention. The machine tool 10 is, for example, a wire electric discharge machine, and includes a bed (base) 1 and a column 2 that is erected on the bed 1 so as to be capable of reciprocating in a horizontal 1-axis direction (Y-axis direction). A ram 3 is installed horizontally on the column 2 so as to be capable of reciprocating in a horizontal 1-axis direction (V-axis direction) parallel to the Y-axis direction, and is fixed to a front side (+Y side) end of the ram 3. And a processing head 5 attached to the support 4. In addition, the processing head 5 is movable in a vertical 1-axis direction (Z-axis direction) supported by the support 4 and in a horizontal 1-axis direction (X-axis direction) with respect to the vertical moving body 5A. And a left and right moving body 5B mounted so as to be able to reciprocate in a horizontal 1-axis direction (U-axis direction) parallel to the table. The up-down moving body 5A and the left-right moving body 5B move integrally in the Z-axis direction. An upper wire guide unit 6 is fixed to the tip of the upper arm of the left and right moving body 5B. The left-right moving body 5B of the processing head 5 is a moving body of a taper mechanism together with the ram 3.

A plurality of rails 11 extending in the Y-axis direction are fixed to the bottom of the ram 3, and these rails 11 are engaged with a plurality of linear guides 12 fixed to the upper portion of the column 2. As a result, the ram 3 is linearly movable relative to the column 2 that is linearly moved in the Y-axis direction, in the axial direction parallel to the Y-axis, that is, in the V-axis direction. A known one can be used as the linear guide 12 as appropriate, and the linear guide 12 and the rail 11 constitute a guide mechanism for positioning and guiding the ram 3 with respect to the column 2.

On the other hand, a plurality of rails 13 extending in the Z-axis direction are fixed to the front end of the support body 4, and these rails 13 are provided with a plurality of linear guides 14 fixed to the surface of the vertical moving body 5A facing the support body 4. Engaged. As a result, the vertical moving body 5 can move relative to the support body 4 in the vertical direction, that is, in the Z-axis direction. In the case of a wire electric discharge machine such as this example, the machining head 5 mainly composed of the vertical moving body 5A and the horizontal moving body 5B attached to the vertical moving body 5A has an upper wire guide via an upper arm. It is configured to support the unit 6. A table on which a workpiece is placed and which can be moved in the horizontal 1-axis direction (X-axis direction) is not shown. Further, the workpiece placed on the table is usually processed in a state of being immersed in the processing liquid in the processing tank attached to the table, but the processing tank and the like are not shown. ..

The column 2 and the ram 3 are connected by a front link body 20F and a rear link body 20R. The link mechanism composed of these two link bodies 20F and 20R is provided on the left and right outer sides of the column 2 and the ram 3, respectively, but in FIG. 1, the link mechanism faces the right side (when viewed from the +Y side to the -Y side). Only those provided on the right side) are shown. The front-side link body 20F and the rear-side link body 20R are arranged so as to be spaced from each other in the front-rear direction, that is, the Y-axis direction.

The front link body 20F and the rear link body 20R each include an upper link 21 and a lower link 22. An upper end of the upper link 21 is rotatably supported by the ram 3 via a shaft 23, and a lower end of the lower link 22 is rotatably supported by the ram 3 via a shaft 25. The lower end side of the upper link 21 and the upper end side of the lower link 22 are rotatably connected to each other via a shaft 24. Further, in each of the front side link body 20F and the rear side link body 20R, the upper link 21 and the lower link 22 are connected to each other in an open state at an angle of less than 180° toward the front, that is, the +Y side.

The front link body 20F and the rear link body 20R behind the front link body 20F are connected by a connection arm 30. The connecting arm 30 constitutes the urging means in the present invention, and has one end portion 31 connected to the front link body 20F, the other end portion 32 connected to the rear link body 20R, the one end portion 31 and others. The compression spring 33 is provided between the end portions 32. The one end portion 31 is connected to the upper link 21 and the lower link 22 via a shaft 24, and is relatively rotatable around the shaft 24 with respect to both links 21 and 22 of the front link body 20F. The other end 32 is also connected to the upper link 21 and the lower link 22 via a shaft 24, and is relatively rotatable around the shaft 24 with respect to both links 21 and 22 of the rear link body 20R. ..

The one end portion 31 is, for example, spline-engaged with a tubular portion accommodating the compression spring 33, thereby preventing the one end portion 31 from rotating around its axis. The other end 32 is also prevented from rotating around its axis in the same manner as above. The connecting arm 30 having the above-described configuration repels in the extending direction by the action of the compression spring 33 when being connected to the front link body 20F and the rear link body 20R. The connecting arm 30 may have any action as long as it has a function of repulsing the front link 20F and the rear link 20R with a predetermined force, and other specifically, for example, the compression spring shown in FIG. A fluid cylinder can be used instead of the cylindrical body containing 33.

The connecting arm 30 as described above applies an upward force to the upper end portion of the upper link 21 of the front link body 20F (that is, the portion connected to the ram 3 via the shaft 23), while the rear link body 20R has the same structure. It acts so as to apply a downward force to the upper end of the upper link 21. Therefore, in the ram 3, an upward force is applied to a portion connected to the front side link body 20F, and a downward force is applied to a portion connected to the rear side link body 20R.

The support 4, the processing head 5, and the upper wire guide unit 6 including the upper arm, which are provided on the front side of the ram 3, apply a downward load to the front side of the ram 3 as compared with the rear side of the ram 3 due to the sum of the respective masses. It is a "heavy element" to give. The ram 3 that supports the heavy elements including the weight of the ram 3 on the front side acts on the ram 3 in a direction to push the front side downward, but a link mechanism including a front link body 20F and a rear link body 20R is used. The force exerted by the connecting arm 30 acts to cancel this moment. It should be noted that "to cancel the moment" does not necessarily mean to completely cancel the moment, but means to reduce the downward force due to this moment. Therefore, it is possible to prevent the positioning accuracy in the electric discharge machining from being lowered due to the moment, and to prevent the electric discharge machine from swinging or vibrating. Further, the above-mentioned force by the link arm composed of the front side link body 20F and the rear side link body 20R and the connecting arm 30 reduces the load biasedly applied to the guide mechanism, so that the wear of the guide mechanism is reduced.

During electric discharge machining, the ram 3 may be moved relative to the column 2 in the front-rear direction (Y-axis direction) by a driving unit (not shown). The above moment increases as the ram 3 moves further forward with respect to the column 2. In the present embodiment, the larger the moment, that is, the more the ram 3 moves to the front side (+Y side), the larger the upward force acting on the ram 3 from the front link body 20F becomes, so that the moment is increased. It is configured so that the canceling action becomes more prominent. Hereinafter, that point will be described in detail.

FIG. 2 schematically shows how the upward force Fv acting on the ram 3 (that is, on the shaft 23) from the upper link 21 of the front side link body 20F changes more greatly as the ram 3 moves as described above. ing. In FIG. 2, when the position of the shaft 23 takes seven positions in the front-rear direction, the force Fv acting on the shaft 23 at each position is shown. In the figure, the upper link 21 and the lower link 22 are shown in a normal form when the shaft 23 takes the foremost position among the above seven positions, but the other six positions are shown. When taken, the upper link 21 and the lower link 22 are shown by one line. As shown here, the more forward the position of the shaft 23, the greater the upward force Fv acting on the shaft 23.

Hereinafter, it will be described that the upward force Fv can be changed as described above. The front link body 20F of FIG. 2 including the upper link 21 and the lower link 22 is considered as a model system as shown in FIG. In this system, the length of the lower link 22 is La, the length of the upper link 21 is Lb, the height of the link body composed of both links 21 and 22 is H, and the angle of the lower link 22 and the upper link 21 with respect to the vertical direction is Let α and β respectively. At this time, if the force B is applied to the connecting portion between the upper link 21 and the lower link 22 by the connecting arm 30 at a downward angle θ, the horizontal component of the force B can be represented by the force A. Therefore, in FIG. 3, the relationship between the force A and the force B is calculated using the force A as a virtual vector as follows.
A=B cos θ−A sin θ·tan α
= B (cos θ-sin θ·tan α)

Here, from the relationship between the length of the upper link 21, the length of each of the lower links 22, the height H of the link body, and the angle θ and the angle β, H=La·cosα+Lb·cosβ
∴ cosβ=(H−La·cosα)/Lb
And, as a general formula, sin β=√(1-cos ² β)
Is. Then, the relationship between the front-rear direction position Y of the upper end of the link body composed of the upper link 21 and the lower link 22 and the link angles α and β is
Y=Lb·sinβ−La·sinα
Is.

First, when a force A is applied in the horizontal direction to the connecting portion between the upper link 21 and the lower link 22, the relationship between the force F and the force A acting on the upper link 21 is as follows.
A-Fsinβ=Fcosβ·tanα
The force F is
F=A/(cos β·tan α+sin β) (1)
Becomes Next, when the force of B is applied to the connecting portion between the upper link 21 and the lower link 22 by the connecting arm 30 at the downward angle θ, not in the horizontal direction, the horizontal component corresponding to A in the above formula (1) is obtained. Is generated, the force A is expressed by the following equation (2).
A=Bcos θ−B sin θ·tan α
∴A=B(cos θ−sin θ·tan α) (2)
Here, when the equation (2) is substituted for the force A in the equation (1),
F=B(cos θ−sin θ·tan α)/(cos β·tan α+sin β)
Therefore, the force Fv, which is the vertical component of the force acting on the upper end of the upper link 21, is
Fv=Fcosβ
Becomes

Based on the above, the force Fv, which is the vertical direction component, is obtained at ten positions when the ram 10 changes its relative position in the V-axis direction (direction parallel to the Y-axis) with respect to the column 11. Was calculated. The values of H, La, Lb, B, and θ at this time are as summarized in Table 1 below. The value of Fv calculated above is shown in Table 2 together with other variables. The position V indicates a position from a predetermined reference position to the front end of the ram 10 in the front-back direction in which the ram 10 linearly moves. This position shows that the larger the positive value, the more the ram 10 is displaced forward from the column 11. The larger this deviation is, the larger the moment generated from the weight of the ram 10 or the like becomes. FIG. 4 is a bar graph showing the values of the vertical component Fv for each angle α at this time.

As is clear from the above, in the present embodiment, the more the ram 3 moves to the front side (+Y side), the larger the upward force Fv acting on the ram 3 from the front link body 20F becomes, and the effect of canceling the moment is obtained. It becomes more prominent.

In the present invention, it is not always necessary to increase the upward force Fv acting on the ram 3 from the front link body 20F as the ram 3 moves to the front side. That is, the upward force Fv may be configured to be substantially constant regardless of the moving position of the ram 3. Regarding the example of such a case, the values of H, La, Lb, B, and θ described above are collectively shown in Table 3 below. In this example, the results obtained by calculating the vertical direction component Fv for each of the 12 positions of the ram 10 in the V-axis direction are shown in Table 4 together with other variables. The position V in Table 4 is the same as that in Table 2 described above. Further, FIG. 5 shows a bar graph of the values of the vertical component Fv for each angle α at this time.

Although the upward force Fv acting on the ram 3 from the front side link body 20F has been described above, the downward force acting on the ram 3 from the rear side link body 20R can be basically obtained based on the above idea. it can. Further, the above is considered with respect to the front side link body 20F provided on the right side of the column 2 and the ram 3 in FIG. 1, but regarding the front side link body 20F provided on the left side of the column 2 and the ram 3, the model system of FIG. It is possible to obtain the upward force Fv acting on the ram 3 and the like by considering a model system in which the left and right sides are opposite.

In the embodiment described above, as shown in FIG. 1, the shaft 24 that connects both links 21 and 22 of the front link body 20F is more than the shaft 24 that connects both links 21 and 22 of the rear link body 20R. Although it is configured to be in a low position, on the contrary, the shaft 24 connecting both the links 21 and 22 of the front link body 20F is connected to the shaft 24 connecting the both links 21 and 22 of the rear link body 20R. It may be configured to be at a higher position, or the two shafts 24 may be configured to be at substantially the same height position.

The connecting arm 30 that connects the front link body 20F and the rear link body 20R is connected to the link bodies 20F and 20R at the shaft 24 that connects the upper link 21 and the lower link 22. The shafts 24 may be configured to be connected to the link bodies 20F and 20R at a portion slightly above or below the shaft 24. Thus, even when the connecting arm 30 connects to the link bodies 20F and 20R at a position slightly separated from the shaft 24, the force by the connecting arm 30 acts on both shafts 24. Therefore, also in this case, the connecting arm 30 as the urging means applies a forward force to the connecting portion of the links 21 and 22 of the front side link body 20F, and also the links 21 and 22 of the rear side link body 20R. This means that a force that is directed rearward is applied to the connecting portion of.

In addition, a forward force is applied to the connecting portion of both links 21 and 22 of the front link body 20F, and a backward force is applied to the connecting portion of both links 21 and 22 of the rear link body 20R. The biasing means is not limited to the connecting arm 30 as described above, and other known means can be used as appropriate.

Although the machine tool 10 of the present embodiment described above is configured such that the ram 3 moves in the V-axis direction parallel to the Y-axis, the present invention is directed to the ram 3 being parallel to the V-axis direction. The present invention can be applied not only to a structure that moves in the Y-axis direction, but also to a machine tool configured so that the ram 3 moves in the X-axis direction. When the ram 3 has a structure that moves in the X-axis direction, the direction along the X-axis may be considered as the front-back direction in the present invention. Furthermore, the present invention can be applied to machine tools other than the wire electric discharge machine.

1 bed 2 column 3 ram 5 processing head 10 machine tool 11, 13 rail 12, 14 linear guide 20F front side link body 20R rear side link body 21 upper link 22 lower link 23, 24, 25 link shaft 30 coupling arm 31 coupling arm 31 End part 32 of the connecting arm of the other end 33 compression spring of the connecting arm

Claims (5)

A column,
A ram arranged above the column,
A guide mechanism that is interposed between the column and the ram, and guides the ram so as to be movable in the front-rear direction with respect to the column,
In a machine tool equipped with
An upper link whose upper end side is rotatably supported by the ram, and a lower link whose lower end side is rotatably supported by the column and whose upper end side is rotatably connected to the lower end side of the upper link, are connected. A link mechanism in which two upper and lower links are opened forward at an angle of less than 180° and two link bodies are provided with a space in the front-rear direction.
Of the two link bodies, the front link body disposed on the front side in the front-rear direction of the two link bodies applies a forward force to the connecting portion between the upper link and the lower link. A biasing means for applying a rearward force to the connecting portion between the upper link and the lower link of the rear link body arranged on the rear side in the front-rear direction,
A machine tool characterized by being provided with. The machine tool according to claim 1, wherein the urging means is a connecting arm that connects the front link body and the rear link body and is provided with a biasing force in an extending direction. The connecting arm includes one end connected to the front link body, the other end connected to the rear link body, and a compression spring interposed between the one end and the other end. The machine tool according to claim 2. One end of the connecting arm is connected to a connecting portion between the upper link and the lower link of the front side link body, and the other end of the connecting arm is a connecting portion between the upper link and the lower link of the rear side link body. The machine tool according to claim 2, which is connected to the machine tool. The machine tool according to any one of claims 1 to 3, wherein the two link bodies are provided on the left and right outer sides of the column and the ram, respectively.