Working machinery

Abstract

The present invention provides a machine tool that, in one cycle of workpiece machining, can perform machining on the end of a workpiece held by the first spindle while it is supported by a centering device, and also perform machining on the back surface of a workpiece held by the second spindle. [Solution] The machine tool 1 comprises a first spindle unit 10 for holding a workpiece W, a second spindle unit 20 for receiving and holding the workpiece W from the first spindle unit 10, a moving mechanism 25 for moving the second spindle unit 20, a tool spindle unit 50 for holding a tool for machining the workpiece W held by the first spindle unit 10 or the second spindle unit 20, a centering device 100 that is inserted into a center hole provided in the workpiece W held by the first spindle unit 10 and supports one end of the workpiece W, and a holder 120 that holds the centering device 100 and moves together with the second spindle unit 20 when the moving mechanism 25 is activated.

Description

Technical Field

[0001] The present invention relates to a machine tool.

Background Art

[0002] When machining a long workpiece, for example, like the machine tool of Patent Document 1, the end of the workpiece is supported by a center device mounted on the second spindle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, a chuck device cannot be attached to the second spindle equipped with the center device, and back machining that involves transferring the workpiece to the second spindle cannot be performed. Therefore, when machining a long workpiece that requires back machining, the machining has to be carried out while pulling out the workpiece on the first spindle side with the second spindle equipped with a chuck device, which has taken a long time.

[0005] The present invention has been made by paying attention to such problems, and an object thereof is to provide a machine tool capable of performing, respectively, machining in a state where the end of the workpiece grasped by the first spindle is supported by a center device and back machining of the workpiece grasped by the second spindle in one cycle of workpiece machining.

Means for Solving the Problems

[0006] To achieve the above objective, the machine tool of the present invention comprises: a first spindle unit for holding a workpiece; a second spindle unit for receiving and holding the workpiece from the first spindle unit; a moving mechanism for moving the second spindle unit; a tool holding unit for holding a tool for machining the workpiece held by the first or second spindle unit; a centering device inserted into a center hole provided in the workpiece held by the first spindle unit to support one end of the workpiece; and a holder for holding the centering device and moving together with the second spindle unit when the moving mechanism is activated. The moving mechanism is capable of moving the second spindle unit in the direction of the axis of the second spindle unit and in an intersecting direction that intersects the axis of the second spindle unit, and the centering device is provided at a position offset in the intersecting direction with respect to the axis of the second spindle unit. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a machine tool that can perform machining on a workpiece with its end portion held by the first spindle supported by a centering device, and on the back surface of a workpiece held by the second spindle, both within a single cycle of workpiece machining. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view of a machine tool according to an embodiment of the present invention. [Figure 2] This is a plan view of a machine tool according to an embodiment of the present invention. [Figure 3] This is a side view focusing on the rear principal axis as seen from arrow III in Figure 2. [Figure 4] This diagram focuses on the center device; (a) is a cross-sectional view along the cutting line IVa-IVa in Figure 3, and (b) is a front view seen from arrow b in (a). [Figure 5] This is a front view showing a workpiece being machined using a centering device. [Figure 6] This is a front view showing the transfer of a workpiece from the first spindle to the rear spindle. [Figure 7] This is a front view showing a workpiece being machined with a deep hole drill. [Modes for carrying out the invention]

[0009] 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 is, for example, a turning center and comprises a bed S which is the base of the entire machine tool 1, a first spindle unit 10 having a first spindle 11, a first spindle moving mechanism 15 for moving the first spindle unit 10, a second spindle unit 20 having a second spindle 21, and a second spindle moving mechanism 25 for moving the second spindle unit 20. As shown in Figure 1, the Y-axis and Z-axis are defined as being orthogonal to each other in the horizontal direction, and the X-axis is defined as being parallel to the height direction. Here, the Z-axis is parallel to the axes (central axes) of the first spindle 11 and the second spindle 21. In the following description, the XYZ coordinate axes defined in this way will be referred to as appropriate.

[0010] As shown in Figure 1, the first spindle unit 10 rotates the workpiece W while holding it. The first spindle unit 10 comprises a first spindle 11 and a first headstock 12 that rotatably supports the first spindle 11. The first spindle 11 is provided with a collet chuck device 90 for holding the end of the workpiece W. The first headstock 12 also has a built-in workpiece rotation motor (not shown) for rotating the first spindle 11.

[0011] The first spindle movement mechanism 15 includes a motor 15a, a ball screw 15b, and a nut 15c. The motor 15a drives the ball screw 15b. The ball screw 15b extends in the Z-axis direction and rotates around a rotation axis parallel to the Z-axis. The rotational force of the motor 15a is converted into linear motion in the Z-axis direction by the ball screw 15b and the nut 15c. As a result, the first headstock 12, which is connected to the nut 15c, moves in the Z-axis direction. The first spindle movement mechanism 15 is installed on the upper surface of the mounting base 17. The mounting base 17 is provided on the upper surface of the bed S.

[0012] The second spindle unit 20 is positioned opposite the first spindle unit 10 in the Z-axis direction. The second spindle unit 20 is located on the +Z side of the first spindle unit 10. As shown in Figures 1 and 2, the second spindle unit 20 comprises a second spindle 21 and a second headstock 22 that rotatably supports the second spindle 21. The second spindle 21 is equipped with a collet chuck device 91 for gripping the end of the workpiece W. The second headstock 22 also has a built-in workpiece rotation motor (not shown) for rotating the second spindle 21. The second headstock 22 is box-shaped and is fixed to the slide table 25SX by bolts (not shown).

[0013] The second spindle movement mechanism 25 includes an X-movement mechanism 25X that moves the second spindle unit 20 in the X-axis direction, and a Z-movement mechanism 25Z that moves the second spindle unit 20 in the Z-axis direction. The second spindle unit 20 does not move in the Y-axis direction.

[0014] As shown in Figure 1, the Z-axis movement mechanism 25Z includes a motor 25Za, a ball screw 25Zb, and a nut 25Zc. The motor 25Za drives the ball screw 25Zb. The ball screw 25Zb extends in the Z-axis direction and rotates around a rotation axis parallel to the Z-axis. The rotational force of the motor 25Za is converted into linear motion in the Z-axis direction by the ball screw 25Zb and the nut 25Zc. As a result, the slide table 25SZ connected to the nut 25Zc moves in the Z-axis direction.

[0015] The X-movement mechanism 25X is mounted on the slide base 25SZ. The X-movement mechanism 25X includes a motor 25Xa, a ball screw 25Xb, and a nut (not shown). The motor 25Xa drives the ball screw 25Xb. The ball screw 25Xb extends in the X-axis direction and rotates around a rotation axis parallel to the X-axis. The rotational force of the motor 25Xa is converted into linear motion in the X-axis direction by the ball screw 25Xb and the nut (not shown). As a result, the slide base 25SX connected to the nut moves in the X-axis direction relative to the slide base 25SZ.

[0016] Further, as shown in FIGS. 1 and 2, the machine tool 1 includes a tool spindle unit 50 as a tool unit, a tool moving mechanism 42, a tool rotating mechanism 45, a tool post 30, a tool post moving mechanism 32, and a tool storage and exchange system 60 in order to process a workpiece W.

[0017] The tool spindle unit 50 has a rotatable tool spindle 52. The tool spindle unit 50 is positioned above the workpiece W held by the first spindle unit 10 or the second spindle unit 20. The tool spindle unit 50 includes a clamp portion 51 configured to be able to mount a fixed tool 70 or a rotating tool 80. The clamp portion 51 is located on the tip side of the tool spindle 52 and grips the shank portions 71, 81 of the tools 70, 80. The tool spindle unit 50 fixedly supports the fixed tool 70 so as not to be axially rotatable and supports the rotating tool 80 so as to be axially rotatable. The tool spindle unit 50 is positioned between the first spindle unit 10 and the second spindle unit 20 in the Z-axis direction. The tool spindle unit 50 processes the workpiece W held by the first spindle unit 10 or the workpiece W held by the second spindle unit 20 with the mounted fixed tool 70 or rotating tool 80.

[0018] As shown in FIG. 2, the tool moving mechanism 42 includes a Y moving mechanism 42Y that moves the tool spindle unit 50 in the Y-axis direction, a Z moving mechanism 42Z that moves the tool spindle unit 50 in the Z-axis direction, and an X moving mechanism 42X that moves the tool spindle unit 50 in the X-axis direction.

[0019] A slide table 42SZ that moves in the Z-axis direction of the Z moving mechanism 42Z moves along a pair of rails 29a extending in the Z-axis direction on the bed S. A slide table 42SY that moves in the Y-axis direction of the Y moving mechanism 42Y moves along a pair of rails 29c extending in the Y-axis direction on the slide table 42SZ. A slide table 42SX that moves in the X-axis direction of the X moving mechanism 42X moves along a pair of rails 29d extending in the X-axis direction on the slide table 42SY.

[0020] The X-axis moving mechanism 42X, the Y-axis moving mechanism 42Y, and the Z-axis moving mechanism 42Z each have a motor, a ball screw, and a nut, and move the tool spindle unit 50 in the X-axis direction, Y-axis direction, and Z-axis direction by converting the rotational force of the motor into linear motion by means of the ball screw and the nut.

[0021] As shown in FIG. 1, the tool rotation mechanism 45 rotates the tool spindle unit 50, thereby rotating the tools 70 and 80 mounted on the tool spindle unit 50 about the rotation axis Ob. The rotation axis Ob is the B-axis parallel to the Y-axis direction. This B-axis is orthogonal to the rotation axes (Z-axes) of the first spindle 11 and the second spindle 21. The rotatable angle θ1 about the rotation axis Ob of the tools 70 and 80 is, for example, 210 degrees.

[0022] The tool rest 30 is configured to be capable of mounting a plurality of tools 35 for machining the workpiece W held by the second spindle 21. The plurality of tools 35 can be attached to the tool rest 30 so as to be arranged in the X-axis direction and the Y-axis direction, respectively. The tool rest 30 is installed on the upper surface of the bed S and is provided at a height that allows the workpiece W sent in the Z-axis direction by the first spindle unit 10 to pass above it.

[0023] The plurality of tools 35 include rotary tools such as drills or end mills that rotate to machine the workpiece W and fixed tools. Each tool 35 is attached to the tool rest 30 in a state of extending along the Z-axis direction. The cutting edge of each tool 35 faces in the direction away from the first spindle unit 10 in the Z-axis direction (+Z side). As shown in FIG. 1, the tool rest 30 includes a tool rotation motor 33 that applies a rotational force to the mounted rotary tool. Near the tool rest 30, workpiece discharging means (not shown) such as a workpiece conveyor, an unloader, or a chute box is provided. By moving the second spindle unit 20 in the X-axis direction, any one of the tools 35 arranged in the X-axis direction can be brought into contact with the workpiece W.

[0024] The tool post moving mechanism 32 is located on the upper surface of the bed S, within a recess 17a formed in the mounting base 17. The tool post moving mechanism 32 moves the tool post 30 in the Y-axis direction. When the tool post 30 moves in the Y-axis direction, it becomes possible to bring one of the multiple tools 35 aligned in the Y-axis direction into contact with the workpiece W held by the second spindle unit 20. The tool post moving mechanism 32, like the Y-movement mechanism 42Y, has a motor, a ball screw, and a nut. The tool post 30 is configured to be immovable in the X-axis direction and the Z-axis direction.

[0025] The tool storage and exchange system 60 stores multiple tools 70, 80 and exchanges one of the stored tools 70, 80 with a tool 70, 80 mounted on the tool spindle unit 50. The tool storage and exchange system 60 comprises a tool storage unit 61 that stores multiple tools 70, 80, and a tool exchange unit 65 that exchanges the tools 70, 80 between the tool storage unit 61 and the tool spindle unit 50.

[0026] The tool storage unit 61 comprises multiple tool magazines 63a, 63b and a drive unit 62. The tool magazines 63a, 63b are roughly annular in shape and are rotatably supported around a rotation axis C5 that extends along the X-axis. In this example, two tool magazines 63a, 63b are arranged side by side on the rotation axis C5. The drive unit 62 has, for example, a tool magazine rotation motor 68 that rotates the tool magazines 63a, 63b around the rotation axis C5.

[0027] The tool changing unit 65 includes a transport unit 67 for inserting and removing tools 70 and 80 from tool magazines 63a and 63b, and an arm unit 66 for exchanging the tool removed from the transport unit 67 with the tool mounted on the tool spindle unit 50.

[0028] Furthermore, the machine tool 1 has a holder 120 for holding the centering device 100 and the deep hole drill 110 below the second spindle unit 20 (in the -X direction). As shown in Figure 4(a), the holder 120 has a first flat plate portion 121 that contacts the +Y-facing surface 25SXa of the slide table 25SX, and a second flat plate portion 122 that rises vertically from one side of the first flat plate portion 121. When viewed from above (facing in the -X direction), the holder 120 has a roughly L-shaped form.

[0029] As shown in Figures 4(a) and 4(b), the first flat plate portion 121 has two bolt holes 126 in the X-axis direction and three in the Z-axis direction for passing bolts 127 through, arranged in a 2x3 configuration. The pitch of the bolt holes 126 in the X-axis direction and the pitch in the Z-axis direction are arbitrary. The bolt holes 126 are counterbored. In addition, screw holes 128 are formed on the surface 25SXa of the slide base 25SX at positions corresponding to the bolt holes 126. The holder 120 is fixed to the slide base 25SX by attaching the bolts 127 passed through the bolt holes 126 to the screw holes 128. The holder 120 is detachable by the bolts 127.

[0030] The second flat plate portion 122 is provided parallel to the XY plane, and the surface 122a facing the -Z side has a step 122c in the Z direction. Of this surface 122a facing the -Z side, the surface on the -Z side due to the step 122c has two mounting holes 123 formed for attaching a tool or centering device 100. The two mounting holes 123 are formed side by side in the X-axis direction, as shown in Figure 4(b). The centerlines of the mounting holes 123 are parallel to the axis C2 of the second spindle 21, as shown in Figure 3, and coincide with the line obtained by offsetting the axis C2 of the second spindle 21 in the -X direction (downward). As shown in Figure 4(b), the centering device 100 is attached to the upper mounting hole 123, and the deep hole drill 110 is attached to the lower mounting hole 123. As shown in Figure 3, if a virtual line L is drawn parallel to the X-axis through the axis C2 of the second spindle unit 20, the axis C3 of the centering device 100 and the axis C4 of the deep hole drill 110 are located on this virtual line L. That is, the positions of the axes C2, C3, and C4 of the second spindle unit 20, the centering device 100, and the deep hole drill 110 are the same in the Y-axis direction. With this configuration, the centering device 100 and the deep hole drill 110 are attached to the slide table 25SX via the holder 120. Therefore, the centering device 100 and the deep hole drill 110 move in the X-axis and Z-axis directions in conjunction with the second spindle unit 20 by the operation of the second spindle movement mechanism 25.

[0031] As shown in Figures 4(a) and 4(b), the center device 100 includes a sleeve holder 101, a center sleeve 102, and a rotating center 103.

[0032] As shown in Figure 4(a), the sleeve holder 101 has a holder portion 101a that holds the center sleeve 102 inserted into the mounting hole 101c, and a rod-shaped member protruding from the holder portion 101a and a shank portion 101b that is inserted into the mounting hole 123. The shank portion 101b inserted into the mounting hole 123 is fixed by two set screws 130 attached from the +Y side surface 122b of the second flat plate portion 122.

[0033] The center sleeve 102 has a substantially cylindrical shape with a mounting hole 102a into which the rotating center 103 is inserted. An enlarged flange portion 102b is formed at the tip (-Z side end) of the center sleeve 102. The flange portion 102b contacts the end face of the sleeve holder 101 when the center sleeve 102 is inserted into the mounting hole 101c, positioning the center sleeve 102 in the Z-axis direction. The mounting hole 102a is tapered, with the diameter decreasing as it gets deeper, to match the shape of the outer circumferential surface of the rotating center 103. The center sleeve 102 inserted into the mounting hole 101c is fixed by three set screws 131 attached from the outer circumferential surface of the sleeve holder 101.

[0034] The rotating center 103 has a central center portion 103a and a sleeve portion 103c that rotatably supports the center portion 103a via a bearing 103b. The center portion 103a has a pointed tip, which is inserted into a center hole drilled in the center of the workpiece W to support the end of the workpiece W during machining. While supporting the workpiece W, the center portion 103a rotates in accordance with the workpiece W. The outer surface of the sleeve portion 103c is formed in a tapered shape, with the diameter decreasing towards the longitudinal direction (direction of the root). The rotating center 103 is fixed by inserting the sleeve portion 103c into a mounting hole 102a formed in the center sleeve 102.

[0035] The deep hole drill 110 is attached to the holder 120 via a drill holder 111, as shown in Figure 4(b). The deep hole drill 110 is held in place by a drill collet (not shown) inside the drill holder 111 so as to have a predetermined protrusion amount.

[0036] Furthermore, as shown in Figures 1 and 2, the machine tool 1 is equipped with a control unit 300 that controls the overall operation of the machine tool 1. The control unit 300 includes ROM (Read Only Memory), RAM (Random Access Memory), CPU (Central Processing Unit), etc. The CPU functions as a central processing unit that executes processing and calculations related to the control of the machine tool 1.

[0037] Next, an example of a machining procedure using machine tool 1 will be described. As shown in Figure 1, the control unit 300 controls the first spindle unit 10, the second spindle unit 20, the first spindle movement mechanism 15, the second spindle movement mechanism 25, the tool post movement mechanism 32, the tool spindle unit 50, the tool movement mechanism 42, the tool rotation mechanism 45, and the tool storage and exchange system 60. The control unit 300 executes the machining process according to a pre-created NC (Numerical Control) program. The workpiece W to be machined in this process is a long, slender cylindrical rod, a so-called long workpiece.

[0038] The control unit 300 has a workpiece W supplied from the rear of the first spindle unit 10 by a workpiece supply unit (not shown), and has the first spindle unit 10 grasp the workpiece W so that it protrudes by a predetermined amount using the following procedure. First, the control unit 300 instructs the tool moving mechanism 42 to position a stopper (not shown) on the side of the tool spindle unit 50 in a predetermined position. Next, the control unit 300 has the workpiece supply unit (not shown) advance the workpiece W until it hits the stopper and stops it. In this way, with the workpiece W protruding by a predetermined amount, the control unit 300 puts the first spindle unit 10 into a clamped state. The amount of protrusion of the workpiece W at this time is smaller than the amount of protrusion when the workpiece W is supported by the centering device 100 described later.

[0039] Next, the control unit 300 drills a center hole in the center of the workpiece W using a rotary tool 80 that has been previously replaced by the tool storage and exchange system 60 and mounted on the tool spindle unit 50. The machining of the center hole may also be performed on the workpiece W after it has been advanced to the amount of protrusion required when the workpiece W is supported by the centering device 100 described later. In this case, the process of advancing the workpiece W can be performed all at once. Before and after machining the center hole, other machining operations may be performed using the tool mounted on the tool spindle unit 50. When performing machining operations other than machining the center hole, the tool in the tool storage and exchange system 60 and the tool in the tool spindle unit 50 are exchanged.

[0040] Next, the control unit 300 advances the workpiece W until it reaches the amount of protrusion required when the centering device 100 supports the workpiece W. Specifically, first, the control unit 300 clamps the end of the workpiece W, which is clamped by the first spindle unit 10, with the second spindle unit 20. Subsequently, the control unit 300 unclams the first spindle unit 10 and retracts the second spindle unit 20 to pull out the workpiece W until it reaches a predetermined amount of protrusion. Subsequently, the control unit 300 clamps the first spindle unit 10 and retracts the second spindle unit 20 while it is in an unclamped state. Alternatively, the positioning of the workpiece W in this case can be performed using a stopper (not shown) on the side of the tool spindle unit 50, as described above. Specifically, the control unit 300 unclams the first spindle unit 10 and advances the workpiece W using a workpiece supply unit (not shown) until it reaches a predetermined amount of protrusion and hits a stopper (not shown) on the side of the tool spindle unit 50 that has been positioned in advance. Then, when the protrusion amount of the workpiece reaches a predetermined amount, the control unit 300 stops the forward movement of the workpiece W and clamps the workpiece W with the first spindle unit 10. The workpiece W may be positioned in this manner.

[0041] Next, the control unit 300 instructs the second spindle movement mechanism 25 to move the center device 100 in the X-axis direction so that the height of the axis C3 of the center portion 103a of the center device 100 matches the height of the axis C1 of the first spindle unit 10. In this way, since the center device 100 is positioned in the -X-axis direction with respect to the axis C2 of the second spindle unit 20, the alignment of the first spindle unit 10 and the center device 100 can be performed by movement in the X-axis direction alone.

[0042] Next, the control unit 300 instructs the second spindle movement mechanism 25 to move the center device 100 in the Z-axis direction so that the tip of the center portion 103a enters the center hole of the workpiece W. This allows one end of the workpiece W, which is held by the first spindle unit 10, to be supported by the center device 100. In this state, the control unit 300 rotates the first spindle 11, causing the center portion 103a to rotate in conjunction with the workpiece W.

[0043] Next, as shown in Figure 5, the control unit 300 supports the workpiece W held by the first spindle unit 10 with the centering device 100, and performs the first machining using the fixed tool 70 (or rotary tool 80) which has been replaced with a tool from the tool storage and exchange system 60 and mounted on the tool spindle unit 50. The tool used in the first machining can be replaced while the centering device 100 is being positioned by moving in the X-axis direction. Alternatively, before and after machining with the tools 70 and 80 mounted on the tool spindle unit 50, as shown in Figure 7, deep hole drilling may be performed on the workpiece W rotating by the first spindle 11 using a deep hole drill 110 attached to a holder 120 below the second spindle 21. Deep hole drilling is performed after moving the deep hole drill 110 in the X-axis direction so that the axis C4 of the deep hole drill is at the same height as the axis C1 of the first spindle unit 10. Alternatively, only deep hole drilling may be performed as the first machining on the workpiece W rotating by the first spindle 11.

[0044] When the first machining is complete, the control unit 300 instructs the second spindle movement mechanism 25 to move the center device 100 to the +Z side, as shown by arrow Y1 in Figure 5, and moves the center device 100 away from the workpiece W. The control unit 300 then moves the second spindle unit 20 in the -X direction (direction of arrow Y2) so that the axis C2 of the second spindle unit 20 is at the same height as the axis C1 of the first spindle unit 10. Subsequently, the control unit 300 unclams the second spindle unit 20 and moves it in the -Z direction (direction of arrow Y3) to the position where it will grip the workpiece W. The control unit 300 then clamps the second spindle unit 20 and holds the workpiece W with the collet chuck device 91, as shown in Figure 6. Simultaneously with the movement of the centering device 100 and the second spindle unit 20, the control unit 300 exchanges the tool stored in the tool storage and exchange system 60 with the tool mounted on the tool spindle unit 50. As a result, a tool such as a parting tool for cutting the workpiece W is mounted on the tool spindle unit 50.

[0045] Next, as shown in Figure 6, the control unit 300 holds both ends of the workpiece W with the first spindle 11 and the second spindle 21, and cuts the workpiece W with a tool such as a parting tool mounted on the tool spindle unit 50 while synchronizing the rotation of the first spindle 11 and the second spindle 21. This transfers the workpiece W from the first spindle unit 10 to the second spindle unit 20. After cutting the workpiece W, the control unit 300 exchanges the tool stored in the tool storage and exchange system 60 with the tool mounted on the tool spindle unit 50. Alternatively, the workpiece W may be transferred from the first spindle 11 to the second spindle 21 without cutting it.

[0046] The control unit 300 then performs a second machining operation on the workpiece W held by the second spindle unit 20 using a tool 35 mounted on the tool post 30 or tools 70, 80 mounted on the tool spindle unit 50. For example, when performing a second machining operation on a workpiece W held by the collet chuck device 91, the control unit 300 may perform turning or milling on the workpiece W using a fixed tool 70 or a rotary tool 80 mounted on the tool spindle unit 50, similar to the first machining operation. Furthermore, if the workpiece W is not supported by the center device 100, machining of the workpiece W on the first spindle 11 using a tool mounted on the tool spindle unit 50 and machining of the workpiece W on the second spindle 21 using a tool 35 mounted on the tool post 30 can be performed simultaneously. This allows machining of the next workpiece W held by the first spindle unit 10 to be performed while the workpiece W held by the second spindle unit 20 is being machined.

[0047] Once the second machining process is complete, the control unit 300 moves the second spindle unit 20 using the second spindle movement mechanism 25 to move the second machined workpiece W to the workpiece discharge position and, in cooperation with a workpiece discharge means (not shown), discharges it to the outside. This completes the machining process. This machining process is repeated each time a workpiece W is supplied.

[0048] The configuration of the machine tool 1 is not limited to the above embodiment. The second spindle moving mechanism 25 has been described as being configured not to move the second spindle unit 20 in the Y-axis direction, but it may also have a Y-axis moving mechanism. Furthermore, the tool post 30 and the tool post moving mechanism 32 are of any configuration and may be omitted.

[0049] Furthermore, the number of mounting holes 123 provided in the holder 120 is arbitrary; there may be more or fewer than two. Also, the axis C2 of the second spindle 21 and the centers of the mounting holes 123 were arranged to be in a straight line on a virtual line L parallel to the X-axis, as shown in Figure 3. However, if the second spindle unit 20 is further equipped with a Y-axis movement mechanism for moving it in the Y-axis direction, these arrangements are not limited to being arranged on a virtual line L parallel to the X-axis. For example, the axis C2 of the second spindle unit and the centers of the mounting holes 123 may be arranged to be in a straight line on a virtual line passing through the axis C2 of the second spindle unit and inclined with respect to the X-axis. Alternatively, the axis C2 of the second spindle 21 and the centers of the mounting holes 123 may not be in a straight line; for example, only the lower (-X side) mounting hole 123 in Figure 3 may be shifted to the right (+Y side) or left (-Y side), or only the upper (+X side) mounting hole 123 may be shifted to the left or right.

[0050] Furthermore, the shape of the sleeve holder 101 and the center sleeve 102 for attaching the rotating center 103 to the holder 120 is arbitrary. Alternatively, the sleeve holder 101 and the center sleeve 102 may be integrated into a single component.

[0051] Furthermore, the mounting position of the center device 100 described above is just one example; the mounting position of the center device 100 is arbitrary as long as the second spindle movement mechanism 25 can appropriately position the collet chuck device 91 or the center device 100 opposite the end face of the workpiece W.

[0052] Furthermore, the workpiece gripping sections of the first spindle 11 and the second spindle 21 are not limited to collet chuck devices; for example, a three-jaw chuck device may also be used.

[0053] Furthermore, the machining of the workpiece W is not limited to the tool spindle; for example, the tool may be mounted on a comb-type or turret-type tool post for machining.

[0054] Alternatively, a workpiece W with a pre-drilled center hole may be supplied directly to the first spindle unit 10 using a loader or the like. In this case, the center hole machining performed before the workpiece W is supported by the centering device 100 is unnecessary.

[0055] Furthermore, in the above embodiment, the two spindles were distinguished using the designations first spindle 11 and second spindle 21, but these designations are merely examples, and they may be interchanged. Alternatively, the first spindle 11 may simply be called the spindle, and the second spindle 21 may be called the back spindle, or these designations may be interchanged.

[0056] Furthermore, although it has been explained that the center provided in the centering device 100 is a rotating center 103, a fixed center may also be attached.

[0057] Furthermore, although it was explained that the holder 120 is attached to the slide table 25SX to which the second spindle unit 20 is attached, the attachment location is arbitrary as long as it is a location that works in conjunction with the second spindle unit 20. For example, the holder 120 may be attached directly to the second spindle unit 20.

[0058] Furthermore, although the description has focused on the case where the second spindle movement mechanism 25 moves in the X-axis direction and the Z-axis direction perpendicular to the axis C2 of the second spindle unit 20, it may also have a movement component in the Z-axis direction and be able to move in a direction such that, for example, it moves in the -X direction and gradually moves in the +Z direction (a direction that intersects the axis C2 of the second spindle unit 20 but does not intersect it perpendicularly). Even in this case, the center device 100 and the deep hole drill 110 can be provided in the direction of movement of the second spindle unit 20.

[0059] Furthermore, the tool holding unit for holding tools for machining workpieces held by the first spindle unit 10 or the second spindle unit 20 is not limited to the tool spindle unit 50. For example, a turret tool post may also be used, as long as it is configured to hold a machinable tool.

[0060] The embodiments described above provide the following effects. (1) In the above embodiment, the machine tool 1 includes a first spindle unit 10 that holds the workpiece W, a second spindle unit 20 that receives and holds the workpiece W from the first spindle unit 10, a moving mechanism (for example, a second spindle moving mechanism 25) that moves the second spindle unit 20, a tool holding unit (for example, a tool spindle unit 50, a tool post 30) that holds a tool for machining the workpiece W held by the first spindle unit 10 or the second spindle unit 20, and a center mount that is inserted into a center hole provided in the workpiece W held by the first spindle unit 10 and supports one end of the workpiece W. The centering device 100 comprises a holder 120 that holds the centering device 100 and moves together with the second spindle unit 20 when a moving mechanism (for example, a second spindle moving mechanism 25) is activated. The moving mechanism (for example, a second spindle moving mechanism 25) is capable of moving the second spindle unit 20 in the direction of the axis C2 of the second spindle unit 20 and in an intersecting direction that intersects the axis C2 of the second spindle unit. The centering device 100 is positioned offset from the axis C2 of the second spindle unit 20 in the intersecting direction (the aforementioned intersecting direction in which the moving mechanism can move the second spindle unit 20). This configuration produces the following effects: (a) to (d). (a) In one cycle of workpiece machining, machining can be performed with the end of the workpiece W held by the first spindle unit 10 supported by the centering device 100, and back surface machining can be performed on the workpiece held by the second spindle unit 20. (b) By supporting one end of the workpiece W with the centering device 100, even when the overhang amount of the workpiece W held by the first spindle unit 10 is long, the deflection of the workpiece W during machining is reduced, enabling high-precision machining. (c) By operating the moving mechanism (for example, the second spindle moving mechanism 25), it is possible to easily switch between machining with the workpiece W supported by the centering device 100 and machining with the workpiece W held by the second spindle unit 20, and the switching does not take any time. (d) Furthermore, since the second spindle unit 20 and the center device 100 share a moving mechanism (for example, the second spindle moving mechanism 25), the machine tool 1 can be made more compact.

[0061] (2) In the machine tool 1 according to the above embodiment, the intersecting direction is perpendicular to the axis C2 of the second spindle unit 20, and the center device 100 is provided below the second spindle unit 20. This configuration produces the effects (e) to (g). (e) By moving the second spindle unit 20 in a direction perpendicular to the axis C2 using a moving mechanism (for example, the second spindle moving mechanism 25), the point at which the axis C1 of the first spindle unit 10 aligns with the axis C2 of the second spindle unit 20 can be changed from the center device 100. Therefore, it is possible to easily switch between machining with the workpiece W supported by the center device 100 and machining with the workpiece W held by the second spindle unit 20. (f) Since the centering device 100 is installed below the second spindle unit 20, it saves space. (g) Because the centering device 100 is installed below the second spindle unit 20, chips and coolant are less likely to come into contact with the centering device 100.

[0062] (3) In the machine tool 1 according to the above embodiment, the holder 120 has at least one mounting hole 123 formed therein for attaching and detaching a tool (for example, a deep hole drill 110) for machining the workpiece W held by the center device 100 or the first spindle unit 10. This configuration produces the effects of (h) to (l). (h) The tool held by the holder 120 can be used to machine the end face of the workpiece W held by the first spindle unit 10. (i) By using a deep hole drill 110 as the tool, deep hole drilling can be performed on the workpiece W held by the first spindle unit 10. (j) The specifications can be easily changed to match the processing of the workpiece W. (k) A tool can be attached in place of the centering device 100, and the number of tools that the holder 120 has can be increased. (l) If the centering device 100 is not needed, it can be removed, and the centering device will not get in the way, allowing for smooth processing.

[0063] (4) In the machine tool 1 according to the above embodiment, two or more mounting holes 123 are formed in the holder 120, and the two or more mounting holes 123 are arranged side by side in a crossing direction. This configuration produces the effect of (m). (m) By moving the second spindle unit 20 in the direction of the axis C2 and in the direction of the intersection, the second spindle unit 20, the centering device 100 and the tool (for example, the deep hole drill 110) can be aligned with the end face of the workpiece W, making switching easy and reducing the time required for switching.

[0064] (5) In the machine tool 1 according to the above embodiment, the holder 120 is attached to a base (for example, a slide base 25SX) to which the second spindle unit 20 is mounted, or is detachably attached to the second spindle unit 20. This configuration produces the effects of (n) to (p). (n) By removing the holder 120, it can be used as a conventional machine tool. (o) By using bolts as a means of attachment and detachment, the holder 120 can be easily attached and detached. (p) The effects of the present invention can be obtained by attaching the holder 120 to an existing machine tool.

[0065] (6) In the machine tool 1 according to the above embodiment, the center device 100 includes a sleeve holder 101 supported by a holder 120, a center sleeve 102 supported by the sleeve holder 101, and a center (for example, a rotary center 103) supported by the center sleeve 102. This configuration produces the effects of (q) to (r). (q) By supporting each component of the center device 100 with, for example, set screws, the center device 100 can be easily attached to and detached. (r) When changing the type of center, the center sleeve 102 can be replaced, making the change easy. [Explanation of Symbols]

[0066] 1...Machine tool, 10...First spindle unit, 11...First spindle, 12...First headstock, 15...First spindle movement mechanism, 15a...Motor, 15b...Ball screw, 15c...Nut, 17...Mounting base, 17a...Recess, 20...Second spindle unit, 21...Second spindle, 22...Second headstock, 25...Second spindle movement mechanism, 25X...X movement mechanism, 25Z...Z movement mechanism, 25SX, 25SZ,...Slide base, 25SXa...Face, 25Xa...Motor, 25Xb...Ball screw, 25Za...Motor T, 25Zb...ball screw, 25Zc...nut, 29a, 29c, 29d...rail, 30...tool post, 32...tool post moving mechanism, 33...motor for tool rotation, 35...tool, 42...tool moving mechanism, 42SX, 42SY, 42SZ...slide base, 42X...X moving mechanism, 42Y...Y moving mechanism, 42Z...Z moving mechanism, 45...tool rotation mechanism, 50...tool spindle unit, 51...clamping section, 52...tool spindle, 60...tool storage and exchange system, 61...tool storage unit, 6 2…Drive unit, 63a,63b…Tool magazine, 65…Tool changing unit, 66…Arm unit, 67…Conveying unit, 68…Motor for rotating tool magazine, 70…Fixed tool, 71…Shank part, 80…Rotating tool, 81…Shank part, 90,91…Collet chuck device, 100…Center device, 101…Sleeve holder, 101a…Holder part, 101b…Shank part, 101c…Mounting hole, 102…Center sleeve, 102a…Mounting hole, 102b…Flange part, 10 3...Rotation center, 103a...Center part, 103b...Bearing, 103c...Sleeve part, 110...Deep hole drill, 111...Drill holder, 120...Holder, 121...First flat plate part, 122...Second flat plate part, 122a,122b...Surface, 122c...Step, 123...Mounting hole, 126...Bolt hole, 127...Bolt, 128...Screw hole, 130,131...Set screw, 300...Control unit, θ1...Angle, C1~C4...Axis center, C5,Ob...Rotation axis, L...Dummy line, S...Bed, W...Workpiece

Claims

1. A first spindle unit that holds the workpiece, A second spindle unit that receives and holds the workpiece from the first spindle unit, A moving mechanism for moving the second spindle unit, A tool holding unit for holding a tool for machining the workpiece held by the first spindle unit or the second spindle unit, A centering device that is inserted into a center hole provided in a workpiece held by the first spindle unit and supports one end of the workpiece, The system includes a holder that holds the center device and moves together with the second spindle unit when the moving mechanism is operated, The moving mechanism is capable of moving the second spindle unit in the direction of the axis of the second spindle unit and in a direction intersecting the axis of the second spindle unit. The center device is positioned at a location offset in the direction perpendicular to the axis of the second spindle unit. Machine tools.

2. The aforementioned intersection direction is perpendicular to the axis of the second main spindle unit. The center device is located below the second spindle unit. The machine tool according to claim 1.

3. The holder has at least one mounting hole formed therein for attaching and detaching a tool for machining a workpiece held by the centering device or the first spindle unit. The machine tool according to claim 1 or 2.

4. Two or more mounting holes are formed in the holder. Two or more of the mounting holes are arranged side by side in the intersecting direction. The machine tool according to claim 3.

5. The holder is attached to a base to which the second spindle unit is mounted, or is detachably attached to the second spindle unit. The machine tool according to claim 1 or 2.

6. The aforementioned center device is A sleeve holder supported by the aforementioned holder, The center sleeve is supported by the sleeve holder, Having a center supported by the center sleeve, The machine tool according to claim 1 or 2.

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