JP7594501B2 - Machine Tools - Google Patents

Description

The present invention relates to a machine tool.

For example, the machine tool described in Patent Document 1 includes a tool table that holds a tool for machining the back surface of a workpiece and is supported on a bed via a support member, a workpiece holding section that uses the tool to machine the back surface of the workpiece while holding the front surface of the workpiece, and a second Z-axis slide mechanism that moves the workpiece holding section in the Z-axis direction to feed the workpiece being machined in the Z-axis direction relative to the tool.

JP 2020-062705 A

In the above-mentioned Patent Document 1, when machining a workpiece, the weight of the workpiece holder can cause delays or vibrations in the movement of the workpiece holder in the Z-axis direction, which can reduce the machining accuracy of the workpiece.

The present invention was made in consideration of the above situation, and aims to provide a machine tool that can improve the machining accuracy of a workpiece.

In order to achieve the above-mentioned object, the machine tool of the present invention comprises a plurality of spindle units which hold and rotate a workpiece, a movable tool unit which is utilized when machining the workpiece held by a specific spindle unit of the plurality of spindle units, a tool moving mechanism configured to move the movable tool unit in an axial direction of the workpiece held by the specific spindle unit, a spindle moving mechanism configured to move the specific spindle unit in the axial direction and in a direction intersecting the axial direction, and a control unit which, when machining an end face in the axial direction of the workpiece held by the specific spindle unit into a curved surface, moves the movable tool unit, which is lighter than the specific spindle unit, in the axial direction via the tool moving mechanism while rotating the workpiece via the specific spindle unit .

The present invention can improve the machining accuracy of the workpiece.

1 is a front view of a machine tool according to an embodiment of the present invention; 1 is a plan view of a machine tool according to an embodiment of the present invention; 1 is a side view of a machine tool according to an embodiment of the present invention; 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 11 is a plan view of a machine tool according to a modified example of the present invention.

Hereinafter, a machine tool according to an embodiment of the present invention will be described with reference to the drawings.
As shown in Figures 1 and 2, the machine tool 1, which is a lathe, comprises a bed S, which is a base of the machine tool 1, a first spindle unit 10 having a first spindle 11, a second spindle unit 20 having a second spindle 21, a first spindle moving mechanism 13Z, second spindle moving mechanisms 25X, 25Z, first tool moving mechanisms 42X, 42Y, a second tool moving mechanism 27Z, a first tool unit 45, a second tool unit 26, a third tool unit 28, and a control unit 300.
In the following, the axial direction along the rotation axis of the first main shaft 11 and the second main shaft 21 is defined as the Z-axis direction, the height direction perpendicular to the Z-axis direction is defined as the Y-axis direction, and the direction perpendicular to the Y-axis and Z-axis directions is defined as the X-axis direction.

As shown in FIG. 1, the first spindle unit 10 holds and rotates the workpiece W. Specifically, the first spindle unit 10 includes a first spindle 11 and a first spindle stock 12 that rotatably supports the first spindle 11. The first spindle 11 grips one end of the workpiece W. The first spindle stock 12 has a built-in workpiece rotation motor (not shown) that rotates the first spindle 11.

The second spindle unit 20 is provided at a position facing the first spindle unit 10 in the Z-axis direction, and holds and rotates the workpiece W received from the first spindle unit 10. The second spindle unit 20 includes a second spindle 21 that grips the other end of the workpiece W, and a second spindle stock 22 that rotatably supports the second spindle 21. A workpiece rotation motor (not shown) that rotates the second spindle 21 is built into the second spindle stock 22.

1, the first spindle moving mechanism 13Z moves the first spindle unit 10 in the Z-axis direction. The second spindle moving mechanism 25Z moves the second spindle unit 20 in the Z-axis direction. The first tool moving mechanism 42Y moves the first tool unit 45 in the Y-axis direction.
2, the second spindle moving mechanism 25X moves the second spindle unit 20 in the X-axis direction to face each of the first spindle 11, the second tool unit 26, and the third tool unit 28. The first tool moving mechanism 42X moves the first tool unit 45 in the X-axis direction.

The second tool moving mechanism 27Z moves the second tool unit 26 in the Z-axis direction. The second tool moving mechanism 27Z is provided at a position farther in the X-axis direction from the first spindle 11 than the second tool unit 26. In addition, the second tool moving mechanism 27Z is located between the motor 25M of the second spindle moving mechanism 25X and the motor 42M of the first tool moving mechanism 42X in the Z-axis direction.

As shown in FIG. 4, the second tool moving mechanism 27Z includes a motor 27A, a ball screw 27B, a nut 27C, a slide support member 27D, a rail portion 27E, a slide portion 27F, a motor support member 27G, and a bearing 27H.
The slide support member 27D is fixed to the bed S. The slide support member 27D is formed with a rail portion 27E extending along the Z-axis direction.
The motor support member 27G supports the motor 27A and is fixed to the slide support member 27D. The motor 27A is located near the motor 25M (see FIG. 2) of the second spindle moving mechanism 25X.

The motor 27A includes an output shaft 27I that rotates under the control of the control unit 300. The output shaft 27I is rotatably supported by a bearing 27H that is fixed to a motor support member 27G. The ball screw 27B is coaxially connected to the output shaft 27I and rotates together with the output shaft 27I.
The slide portion 27F is provided movably along the rail portion 27E and supports the nut 27C. The slide portion 27F is positioned so as to sandwich the motor support member 27G between the slide portion 27F and the motor 27A in the Z-axis direction. As shown in FIG. 3, the slide portion 27F is hat-shaped when viewed from the Z-axis direction. The slide portion 27F includes a support table 27J that supports the second tool unit 26 at the same height as the second spindle 21 (see FIG. 1). The support table 27J is flat and extends along the X-axis and Z-axis directions, and the second tool unit 26 is installed on the upper surface of the support table 27J. The second tool unit 26 is located at an end of the support table 27J close to the third tool unit 28.
4, the nut 27C is fitted onto the outer periphery of the ball screw 27B. When the output shaft 27I and the ball screw 27B are rotated by the motor 27A, the nut 27C moves in the Z-axis direction together with the slide portion 27F along the ball screw 27B.
As shown in Figures 1 and 2, the first spindle moving mechanism 13Z, the second spindle moving mechanisms 25X, 25Z, and the first tool moving mechanisms 42X, 42Y each have a motor, a ball screw, a nut, etc., similar to the second tool moving mechanism 27Z.

As shown in FIG. 2, the first tool unit 45 machines the workpiece W gripped by the first spindle 11. The first tool unit 45 includes a plurality of tools 45a and a tool holder 45b that holds the plurality of tools 45a. The tools 45a are, for example, a cutting tool or a drill.

The second tool unit 26 machines the workpiece W gripped by the second spindle 21 and is configured to be movable in the Z-axis direction by the second tool moving mechanism 27Z. The second tool unit 26 includes a single tool 26a and a tool holder 26b that holds the tool 26a. The tool 26a is, for example, a cutting tool. The tool 26a extends along the Z-axis direction. The second tool unit 26 is lighter than both the second spindle unit 20 and the third tool unit 28.

The third tool unit 28 machines the workpiece W gripped by the second spindle 21, and is fixedly provided with respect to the bed S. The third tool unit 28 is provided to the side of the second tool unit 26, and is provided between the second tool unit 26 and the first spindle 11 in the X-axis direction.
The third tool unit 28 includes a plurality of tools 28a and a tool holder 28b for holding the plurality of tools 28a. The plurality of tools 28a each extend along the Z-axis direction and are arranged in the X-axis direction. The tools 28a are, for example, a cutting tool or a drill. The tools 28a are located at the same height as the tools 26a in the Y-axis direction.

As shown in Figures 1 and 2, the control unit 300 controls the first spindle unit 10, the second spindle unit 20, the first spindle movement mechanism 13Z, the second spindle movement mechanisms 25X, 25Z, the first tool movement mechanisms 42X, 42Y, and the second tool movement mechanism 27Z. The control unit 300 includes, for example, a CPU (Central Processing Unit) (not shown) and a ROM (Read Only Memory) that stores a program that defines the procedure of processing by the CPU.

Next, a description will be given of the machining process executed by the control unit 300. The control unit 300 executes this machining process in accordance with an NC (Numerical Control) program created in advance.
The control unit 300 performs a first machining process on the workpiece W held by the first spindle 11, using the first tool unit 45. For example, when cutting the outer diameter of the workpiece W as the first machining process, the control unit 300 moves the cutting edge of the tool 45a, which is a cutting tool, via the first tool moving mechanisms 42X, 42Y to a position in contact with the outer circumferential surface of the workpiece W held by the first spindle 11, and feeds the workpiece W in the Z-axis direction via the first spindle moving mechanism 13Z while rotating the first spindle 11 together with the workpiece W.

When the first machining is completed, the control unit 300 moves the second spindle unit 20 in the X-axis direction and the Z-axis direction via the second spindle moving mechanisms 25X, 25Z so that the second spindle 21 faces the first spindle 11. Then, the control unit 300 transfers the workpiece W that has completed the first machining from the first spindle 11 to the second spindle 21.

Next, the control unit 300 performs the second machining of the workpiece W held by the second spindle 21 using the second tool unit 26 or the third tool unit 28. When performing the second machining with the second tool unit 26, the control unit 300 adjusts the relative positions of the tool 26a and the workpiece W in the X-axis direction and the Z-axis direction via the second spindle moving mechanism 25X and the second tool moving mechanism 27Z, and does not operate the second spindle moving mechanism 25Z. Therefore, when performing this second machining, the second spindle 21 does not move in the Z-axis direction. For example, when machining the end face of the workpiece W into a curved surface as the second machining, the control unit 300 rotates the second spindle 21 together with the workpiece W, and moves the tool 26a in the Z-axis direction via the second tool moving mechanism 27Z and the second spindle 21 in the X-axis direction via the second spindle moving mechanism 25X. When machining the end face of the workpiece W into a curved surface, it is necessary to synchronize the rotational position of the workpiece W with the positions of the tool 26a in the X-axis and Z-axis directions. In this regard, in this embodiment, the second tool unit 26, which is lighter than the second spindle unit 20, is moved in the Z-axis direction, so that the tracking ability of the position of the tool 26a in the Z-axis direction relative to the rotational position of the workpiece W can be improved, and the machining accuracy of the workpiece W is improved.

The second machining is not limited to the curved surface machining of the end face of the workpiece W by the tool 26a, but may be cutting of the outer diameter of the workpiece W by the tool 26a, or machining of the workpiece W by the tool 28a of the third tool unit 28. When machining the workpiece W by the tool 28a, the control unit 300 moves the workpiece W in the X-axis direction and the Z-axis direction relative to the tool 28a via the second spindle movement mechanisms 25X and 25Z.

Depending on the type of machining, either the second tool unit 26 or the third tool unit 28 may be selected. For example, the control unit 300 may use the second tool unit 26 to perform curved surface machining of the end face of the workpiece W, and may use the third tool unit 28 to perform machining other than this curved surface machining.

The advantage of the third tool unit 28 is that it is immovable relative to the bed S, so it has high rigidity, and since it does not have a ball screw or the like, it is less susceptible to the effects of thermal displacement. On the other hand, the advantage of the second tool unit 26 is that it is lightweight and can be moved at high speed. Taking into account the above advantages, either the second tool unit 26 or the third tool unit 28 may be selected.

When the second machining is completed, the control unit 300 discharges the workpiece W that has been subjected to the second machining from the second spindle 21 to a workpiece catcher (not shown). The workpiece W discharged to the workpiece catcher is transported to the outside of the machine by a workpiece conveyor (not shown).
This completes the machining process. This machining process is performed for each workpiece W to be machined.

(effect)
According to the embodiment described above, the following effects are achieved.
(1) The machine tool 1 includes a first spindle unit 10 and a second spindle unit 20 which are examples of a plurality of spindle units that rotate a workpiece W while holding it, a second tool unit 26 which is an example of a movable tool unit used when machining a workpiece W held by the second spindle unit 20 which is an example of a specific spindle unit, a second tool moving mechanism 27Z which is an example of a tool moving mechanism configured to move the second tool unit 26 in a Z-axis direction which is an example of an axial direction of the workpiece W held by the second spindle unit 20, and second spindle moving mechanisms 25X, 25Z which are examples of a spindle moving mechanism configured to move the second spindle unit 20 in the Z-axis direction and in an X-axis direction intersecting the Z-axis direction.
According to this configuration, when the workpiece W held by the second spindle unit 20 is machined by the second tool unit 26, the second tool moving mechanism 27Z can move the second tool unit 26 in the Z-axis direction. Therefore, during this machining, it is not necessary to move the heavy second spindle unit 20 in the Z-axis direction. Therefore, during this machining, the second tool unit 26 can move relatively to the workpiece W at high speed and stably with little vibration. Therefore, the machining accuracy of the workpiece W can be improved.

(2) The machine tool 1 includes a control unit 300 that, when machining an end face of a workpiece W held by the second spindle unit 20 into a curved surface, moves the second tool unit 26 in the Z-axis direction via the second tool moving mechanism 27Z while rotating the workpiece W via the second spindle unit 20. The second tool unit 26 is lighter than the second spindle unit 20.
Generally, when machining a curved surface while rotating a workpiece, if the movement of the tool is delayed relative to the rotation of the workpiece, the rotational position of the workpiece and the cutting edge position of the tool will not be synchronized, and machining accuracy will decrease. In this regard, according to the above configuration, the second tool unit 26, which is lighter than the second spindle unit 20, is moved when machining the end face of the workpiece W into a curved surface. Therefore, delay in the movement of the second tool unit 26 in the Z-axis direction relative to the rotation of the workpiece W is suppressed, and machining accuracy can be improved.

(3) The machine tool 1 is equipped with a third tool unit 28 which is an example of a fixed tool unit that is used when machining the workpiece W held by the second spindle unit 20, is immovable relative to the bed S, and is located near the second tool unit 26.
According to this configuration, by preparing the third tool unit 28 separately from the second tool unit 26, it is possible to reduce the number of tools 26a held by the second tool unit 26 that is movable in the Z-axis direction. Therefore, it is possible to reduce the weight of the second tool unit 26, and as described above, the machining accuracy of the workpiece W by the second tool unit 26 is improved.
Moreover, in terms of rigidity or thermal displacement, the third tool unit 28 is superior to the second tool unit 26. For this reason, in machining that requires high rigidity from the tool unit or machining under conditions where the effect of thermal displacement is large, the third tool unit 28 is used to improve the machining accuracy of the workpiece W.

Note that this disclosure is not limited to the above-described embodiments and drawings. Modifications (including the deletion of components) may be made as appropriate within the scope of the present disclosure without changing its gist. An example of a modification is described below.

(Modification)
In the above embodiment, the second tool unit 26 is configured to be movable in the Z-axis direction, but may be configured to be movable in the X-axis direction in addition to the Z-axis direction. For example, as shown in FIG. 5, the machine tool 1 includes a second tool moving mechanism 27X that moves the second tool unit 26 in the X-axis direction. The second tool moving mechanism 27X has a motor, a ball screw, a nut, and the like, similar to the second tool moving mechanism 27Z. In the modified example of FIG. 5, when machining the end face of the workpiece W into a curved surface as the second machining, the control unit 300 moves the tool 26a in the X-axis direction and the Z-axis direction via the second tool moving mechanisms 27X and 27Z while rotating the second spindle 21 together with the workpiece W. By moving the second tool unit 26 in the X-axis direction by the second tool moving mechanism 27X during machining of the workpiece W, it is not necessary to move the heavy second spindle unit 20 in the X-axis direction. This makes it possible to improve the machining accuracy of the workpiece W.

In the modified example of FIG. 5 above, the third tool unit 28 is fixed to the bed S, but this is not limited thereto, and the third tool unit 28 may be fixed to a slide base 27S (see FIG. 5) that moves in the X-axis direction of the second tool movement mechanism 27X. This allows the height of the third tool unit 28 to be made lower than when the third tool unit 28 is fixed to the bed S, thereby increasing the rigidity of the third tool unit 28.

In the above embodiment, the control unit 300 may perform overlap machining in which the first machining and the second machining are performed simultaneously. During this overlap machining, as shown in Figs. 1 and 2, the control unit 300 uses the first tool unit 45 to machine the first workpiece W1, which is the workpiece W held by the first spindle unit 10, and simultaneously uses the second tool unit 26 to machine the second workpiece W2, which is a workpiece W different from the first workpiece W1, held by the second spindle unit 20. By overlapping the machining time of the first workpiece W1 by the first tool unit 45 and the machining time of the second workpiece W2 by the second tool unit 26, the cycle time, which is the machining time for each workpiece W, can be shortened.

In the above embodiment, the second tool unit 26 includes a single tool 26a. However, the number of tool 26a is not limited to one, and the second tool unit 26 may include a plurality of tools 26a.
In the above embodiment, the tool 26a is a cutting tool, but is not limited to this and may be a drill, an end mill, or the like.
The second tool unit 26 or the third tool unit 28 in the above-described embodiment may be configured to be movable in the Y-axis direction, whereby a plurality of tools 26a, 28a can be arranged in the Y-axis direction.
The third tool unit 28 in the above embodiment may be omitted.

In the above embodiment and modified example, the second tool moving mechanisms 27X, 27Z are configured to move the second tool unit 26 using a motor and a ball screw or the like, but this is not limited thereto. For example, the second tool unit 26 may be moved by a linear motion mechanism such as a linear motor.

Taking into account the above-mentioned advantages, for example, the control unit 300 may use the third tool unit 28 to machine the workpiece W when the influence of thermal displacement is large, and may use the second tool unit 26 to machine the workpiece W when the influence of thermal displacement is small. In this case, after the start of the machine tool 1, the control unit 300 determines that the influence of thermal displacement is large until a specified time has elapsed, and uses the third tool unit 28 to machine the workpiece W. On the other hand, after the specified time has elapsed, the control unit 300 determines that the influence of thermal displacement is small, and uses the second tool unit 26 to machine the workpiece W.

The control unit 300 may also obtain the amount of thermal displacement based on the detection result of a sensor that detects the amount of thermal displacement of the ball screw 27B (see FIG. 4) of the second tool moving mechanism 27Z. When the obtained amount of thermal displacement exceeds a threshold, it is determined that the influence of the thermal displacement is large, and the third tool unit 28 is used to machine the workpiece W, and when the obtained amount of thermal displacement is equal to or less than the threshold, it is determined that the influence of the thermal displacement is small, and the second tool unit 26 is used to machine the workpiece W.
Furthermore, the control unit 300 may use the third tool unit 28 to machine the workpiece W when the machining resistance value generated in the tool during machining, such as cutting resistance value, exceeds a threshold value, and may use the second tool unit 26 to machine the workpiece W when the machining resistance value is below the threshold value.

1...machine tool, 10...first spindle unit, 11...first spindle, 12...first spindle stock, 13Z...first spindle movement mechanism, 20...second spindle unit, 21...second spindle, 22...second spindle stock, 25M, 27A, 42M...motor, 25X, 25Z...second spindle movement mechanism, 26...second tool unit, 26a, 28a, 45a...tool, 26b, 28b, 45b...tool holder, 27B...ball screw, 27C...nut, 27 D...slide support member, 27E...rail portion, 27F...slide portion, 27G...motor support member, 27H...bearing, 27I...output shaft, 27J...support table, 27S...slide base, 27X, 27Z...second tool movement mechanism, 28...third tool unit, 42X, 42Y...first tool movement mechanism, 45...first tool unit, 300...control unit, S...bed, W...workpiece, W1...first workpiece, W2...second workpiece

Claims (4)

A plurality of spindle units that hold and rotate a workpiece;
a movable tool unit that is used when machining the workpiece held by any one of the plurality of spindle units;
a tool moving mechanism configured to move the movable tool unit in an axial direction of the workpiece held by the specific spindle unit;
a spindle moving mechanism configured to be able to move the specific spindle unit in the axial direction and in a direction intersecting the axial direction;
and a control unit that moves the movable tool unit, which is lighter than the specific spindle unit, in the axial direction via the tool moving mechanism while rotating the workpiece via the specific spindle unit when machining an end surface in the axial direction of the workpiece held by the specific spindle unit into a curved surface.
Machine tools. The tool moving mechanism is configured to be able to move the movable tool unit in the axial direction as well as in a direction intersecting the axial direction.
The machine tool according to claim 1 . A fixed tool unit is used when machining the workpiece held by the specific spindle unit, and is provided immovably with respect to the bed and located near the movable tool unit.
3. A machine tool according to claim 1 or 2 . The plurality of spindle units include
A first spindle unit that holds and rotates one end of the workpiece;
a second spindle unit which is the specific spindle unit and rotates the other end of the workpiece received from the first spindle unit,
The machine tool comprises:
a first tool unit that is used when machining the workpiece held by the first spindle unit;
a control unit that uses the first tool unit to machine a first workpiece held by the first spindle unit, and simultaneously uses the second tool unit to machine a second workpiece held by the second spindle unit and different from the first workpiece,
A machine tool according to any one of claims 1 to 3 .