JP7610420B2 - Gear train assembly method, gear train, tool unit and machine tool - Google Patents

Description

The present invention relates to a gear train assembly method, a gear train, a tool unit, and a machine tool.

For example, the B-axis rotating tool unit described in Patent Document 1 has multiple spur gears that mesh with each other, and the tool is rotated together with the multiple spur gears by the driving force from the motor.

JP 2019-181653 A

In the configuration described in the above Patent Document 1, multiple spur gears are used as the gear train, but spur gears make it difficult to rotate smoothly at high speeds. Therefore, the inventors of the present application have considered using multiple double helical gears (double helical gears) as the gear train. This double helical gear can rotate smoothly even at high speeds compared to spur gears, and is suitable for transmitting large rotational forces. In addition, this double helical gear has the advantage of being able to cancel the thrust force generated by the helical gear. However, when manufacturing a double helical gear as an integral unit, it is necessary to provide a groove between the pair of helical gears to allow the grinding wheel to escape during tooth grinding, so the double helical gear becomes large in the axial direction. On the other hand, in a double helical gear in which a pair of separate helical gears are connected by bolts or the like, the above groove is not necessary, but the pair of helical gears must be aligned with high precision to prevent one-sided contact in which only one of the pair of helical gears meshes, and this alignment is difficult. In addition, due to the structure of double helical gears, it is impossible to pull multiple double helical gears out in the axial direction after they are meshed together, so they must be assembled in a meshed state. As such, assembling double helical gears has been difficult.

The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a gear train assembly method, a gear train, a tool unit, and a machine tool that facilitate the assembly of double helical gears.

In order to achieve the above object, a gear train assembly method according to a first aspect of the present invention provides a gear train comprising a plurality of double helical gears arranged to mesh with each other, the double helical gears having a plurality of teeth extending obliquely with respect to a rotation axis of the double helical gears, each of which is formed as a separate body, and a connecting member that connects the first and second helical gear portions together in a state in which the first and second helical gear portions are overlapped in a direction along the rotation axis, the connecting member being capable of connecting the first helical gear portion and the second helical gear portion in a temporary connected state that allows relative displacement around the rotation axis, and the method comprises an adjustment step of adjusting the meshing of the first helical gear portions and the meshing of the second helical gear portions by operating the gear train in a state in which the first helical gear portion and the second helical gear portion are connected in the temporary connected state by the connecting member when assembling the double helical gear.
In order to achieve the above object, a gear train according to a second aspect of the present invention is a gear train comprising a plurality of double helical gears arranged to mesh with each other, the double helical gears having a plurality of teeth extending obliquely with respect to a rotation axis of the double helical gears, the gear train comprising first and second helical gear portions formed as separate bodies, and a connecting member connecting the first and second helical gear portions in a state in which the first and second helical gear portions are overlapped in a direction along the rotation axis, the connecting member allowing relative displacement between the first helical gear portion and the second helical gear portion about the rotation axis. In both cases, the first helical gear portion and the second helical gear portion can be temporarily connected together so that the meshing between the first helical gear portions and the meshing between the second helical gear portions can be adjusted by the operating gear train, and the multiple double helical gears are three or more double helical gears, and by removing the connecting member of a specific gear of any of the three or more double helical gears while the three or more double helical gears are meshed with each other, the second helical gear portion of the specific gear can be independently attached and detached from the first helical gear portion.

In order to achieve the above object, a tool unit according to a third aspect of the present invention is a tool unit having the gear train, wherein the first helical gear portion includes a tool support portion that supports a tool rotatably together with the first helical gear portion.

In order to achieve the above object, a machine tool according to a fourth aspect of the present invention comprises the tool unit and a work fixing portion which fixes the work when the work is machined by the tool rotated by the tool unit.

According to the present invention, the gear train assembly method, the gear train, the tool unit, and the machine tool facilitate the assembly of a double helical gear.

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; FIG. 2 is a side view of the tool unit with a cover portion removed from the gear box according to the embodiment of the present invention. 4 is a cross-sectional view taken along line AA of FIG. 3. FIG. 5 is an enlarged view of area B in FIG. 4 . 5A is a front view of a second helical gear according to one embodiment of the present invention, and FIG. 5B is a cross-sectional view of the second helical gear. 1A is a front view of a first helical gear according to one embodiment of the present invention, and FIG. 1B is a side view of the first helical gear. FIG. 2 is a perspective view of a gear box and a first helical gear according to an embodiment of the present invention. FIG. 2 is a perspective view of a gear box, a first helical gear, a second helical gear, and a connecting member according to an embodiment of the present invention. 1A to 1D are schematic diagrams showing a procedure for replacing a specific gear according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A gear train, a tool unit, and a machine tool according to an embodiment of the present invention will be described below with reference to the drawings.
As shown in Figures 1 and 2, machine tool 1, which is a turning center, comprises a bed S, which is a base for the entire machine tool 1, a first spindle unit 10 having a first spindle 11, a second spindle unit 20 having a second spindle 21, a second spindle moving mechanism 25, a tool unit 30, a tool moving mechanism 42, a B-axis rotation mechanism 45, a tool spindle unit 50, a tool magazine 60, 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 X-axis direction, and the direction perpendicular to the X-axis and Z-axis directions is defined as the Y-axis direction.

The first spindle unit 10 grips 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. A workpiece rotation motor (not shown) that rotates the first spindle 11 is built into the first spindle stock 12. The first spindle unit 10 is configured to be immovable relative to the bed S.

The second spindle unit 20 is provided at a position facing the first spindle unit 10 in the Z-axis direction. 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.

The second spindle movement mechanism 25 includes a Y movement mechanism 25Y that moves the second spindle unit 20 in the Y-axis direction (Y2-axis direction) as shown in FIG. 2, an X movement mechanism 25X that moves the second spindle unit 20 in the X-axis direction (X2-axis direction) as shown in FIG. 1, and a Z movement mechanism 25Z that moves the second spindle unit 20 in the Z-axis direction (Z2-axis direction).

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 (Y1 axis direction), as shown in FIG. 1, an X moving mechanism 42X that moves the tool spindle unit 50 in the X axis direction (X1 axis direction), and a Z moving mechanism 42Z that moves the tool spindle unit 50 in the Z axis direction (Z1 axis direction).
As shown in FIG. 2, the slide table 25S, which moves in the Z-axis direction of the Z movement mechanism 25Z, and the slide table 42S, which moves in the Z-axis direction of the Z movement mechanism 42Z, move along a common rail 29 extending in the Z-axis direction on the bed S.

The X-movement mechanism 25X, 42X, the Y-movement mechanism 25Y, 42Y, and the Z-movement mechanism 25Z, 42Z each have a motor, a ball screw, and a nut, and are configured to linearly move the corresponding second spindle unit 20 or tool spindle unit 50 by converting the rotational force of the motor into linear motion using the ball screw and the nut.

The B-axis rotation mechanism 45 rotates the tool spindle unit 50 in the B-axis direction. The B-axis direction is a rotation direction centered on a rotation axis along the Y-axis direction.
The tool magazine 60 holds a plurality of tools 70 of different types, and transfers the tools 70 between the tool spindle unit 50. The tool spindle unit 50 is, for example, a tool spindle, and supports the tools 70 rotatably.

The tool unit 30 is a tool rest on which a tool 80 can be attached for machining the workpiece W held by the second spindle 21. The tool 80 is a rotating tool such as a drill or end mill that rotates to machine the workpiece W. The tool 80 is attached to the tool unit 30 in a state where it extends along the Z-axis direction.

4, the tool unit 30 includes a drive unit 31 and a gear train 30T. The gear train 30T includes a gear box 32, bearings 33a, 33b, and 33c, a drive gear 34, a plurality of driven gears 35, and a wave washer 39.
The driving unit 31 is a motor that rotates the driving gear 34. The driving unit 31 is located to the side of the tool 80 attached to the tool unit 30.
The driving unit 31 has an output shaft 31a. The output shaft 31a extends along the Z-axis direction and rotates about its axis. The driving unit 31 is fixed to a gear box 32.
The drive gear 34 is supported rotatably about a rotation axis I of the drive gear 34 via a bearing 33a in a drive gear accommodating space 32b (described later) in the gear box 32. The rotation axis I extends along the Z-axis direction.
An output shaft 31a of the drive unit 31 is fixed to the drive gear 34. The drive gear 34 rotates together with the output shaft 31a about a rotation axis I. The drive gear 34 is a double helical gear. A specific configuration of the drive gear 34 will be described later.

The multiple driven gears 35 are double helical gears arranged to mesh with each other. Each driven gear 35 is supported rotatably around the rotation axis I of the driven gear 35 via bearings 33b and 33c in a driven gear storage space 32a (described later) in the gear box 32. The multiple driven gears 35 transmit the rotational force from the drive gear 34 to the tool 80.

As shown in FIG. 3, the multiple driven gears 35, ie, driven gears 35A to 35H, are arranged on a plane together with the drive gear .
The driven gears 35C to 35E are aligned in the Y axis direction so as to mesh with one another, and the driven gears 35F to 35H are aligned in the Y axis direction so as to be parallel to the driven gears 35C to 35E.
The driven gear 35B is located between the driven gears 35C and 35F in the X-axis direction so as to mesh with the driven gears 35C and 35F. The driven gear 35A is located between the drive gear 34 and the driven gear 35A so as to mesh with the drive gear 34 and the driven gear 35A. The diameters of the driven gears 35A to 35H are the same and are smaller than the diameter of the drive gear 34.

Next, a specific configuration of each driven gear 35 will be described.
As shown in FIG. 5 , each driven gear 35 includes a first helical gear portion 36 , a second helical gear portion 37 , and a plurality of connecting members 38 .
7A and 7B, the first helical gear portion 36 includes a gear body portion 36h having teeth 36a, shaft portions 36c and 36e, and a tool support portion 36d. The gear body portion 36h is formed in a disk shape. The teeth 36a are formed on the outer circumferential surface of the gear body portion 36h.
As shown in FIG. 8 , each tooth portion 36 a extends obliquely with respect to the rotation axis I and is aligned in the rotation direction C of the first helical gear portion 36 .

7A, the gear body 36h has a plurality of screw holes 36b formed therein. The screw holes 36b are arranged at equal angular intervals in the rotational direction C of the first helical gear portion 36.
As shown in Fig. 7(b), the shaft portions 36c and 36e are cylindrical and extend along the rotation axis I. The shaft portion 36e is provided at the center of the front surface of the gear body portion 36h close to the tool 80 (see Fig. 5). The shaft portion 36c is provided at the center of the rear surface of the gear body portion 36h. As shown in Fig. 5, bearings 33b and 33c are provided on the outer circumferential surfaces of the shaft portions 36c and 36e, respectively.

The tool support portion 36d supports the base end of the tool 80. The tool support portion 36d is formed in a concave shape so that the base end of the tool 80 fits into the tip of the shaft portion 36e. The base end of the tool 80 is detachable from the tool support portion 36d.

As shown in Fig. 6, the second helical gear portion 37 is in the shape of a ring extending in a direction perpendicular to the rotation axis I. The second helical gear portion 37 has a plurality of teeth 37a formed on the outer circumferential surface of the second helical gear portion 37. As shown in Fig. 9, each tooth 37a extends obliquely with respect to the rotation axis I and is arranged on the outer circumferential surface of the second helical gear portion 37 along the rotation direction C.
Each tooth portion 36 a (tooth trace) of the first helical gear portion 36 and each tooth portion 37 a (tooth trace) of the second helical gear portion 37 are formed in different directions with respect to the rotation axis I.
Furthermore, as shown in a simplified manner in Fig. 4, the tooth traces 35z of the mutually meshing driven gears 35 are formed to be oriented in opposite directions. In this example, the tooth traces 35z of the driven gears 35A, 35C, 35E, 35F, and 35H shown in Fig. 3 are oriented in opposite directions to the tooth traces 35z of the driven gears 35B, 35D, and 35G when viewed from the gear radial direction. The tooth traces of the drive gear 34 are oriented in the same direction as the tooth traces 35z of the driven gears 35B, 35D, and 35G.

6(a) and 6(b), a shaft passing hole 37d and a plurality of connecting member passing holes 37b, 37c are formed in the second helical gear portion 37. The shaft passing hole 37d is located in the center of the second helical gear portion 37 and is formed to allow the shaft portion 36c of the first helical gear portion 36 to pass therethrough, as shown in FIG.
As shown in FIG. 6A, the coupling member passing holes 37b, 37c are arranged at equal angular intervals along the rotational direction C.

As shown in Figures 5 and 6(b), the coupling member passing holes 37b and 37c are formed as through holes that penetrate the second helical gear portion 37 in the thickness direction. The coupling member passing hole 37b accommodates the head 38a of the coupling member 38. The coupling member passing hole 37c allows the threaded shaft portion 38b of the coupling member 38 to pass through. The coupling member passing hole 37c is located closer to the gear body portion 36h of the first helical gear portion 36 than the coupling member passing hole 37b, and has a smaller diameter than the coupling member passing hole 37b.

The connecting member 38 connects the overlapping first helical gear portion 36 and second helical gear portion 37. The connecting member 38 is, for example, a bolt. The connecting member 38 has a head portion 38a and a threaded shaft portion 38b. The head portion 38a of the connecting member 38 is located in a connecting member passing hole 37b of the second helical gear portion 37. The threaded shaft portion 38b of the connecting member 38 passes through a connecting member passing hole 37c of the second helical gear portion 37 and is screwed into the threaded hole 36b of the first helical gear portion 36.
9, the teeth 36a of the first helical gear portion 36 and the teeth 37a of the second helical gear portion 37 are disposed at offset positions (phases) in the rotational direction C. The offset amounts of the teeth 36a, 37a between the driven gears 35 are the same.

Next, the specific configuration of the drive gear 34 will be described, focusing on the differences from the driven gear 35.
As shown in FIG. 4, like the driven gear 35, the drive gear 34 includes a first helical gear portion 34a, a second helical gear portion 34b, and a connecting member 34c.
The first helical gear portion 34a includes shaft portions 34d, 34e extending along the rotation axis I of the drive gear 34. The shaft portion 34d extends toward the drive unit 31, and the output shaft 31a of the drive unit 31 is inserted and fixed at the center of the shaft portion 34d. The shaft portion 34e is provided on the opposite side of the shaft portion 34d of the first helical gear portion 34a. A recess 34f is formed in the shaft portion 34e, and a head portion 31b fixed to the tip of the output shaft 31a is located in the recess 34f. The recess 34f is formed on the end surface of the shaft portion 34e so as to open in the direction opposite to the drive unit 31.

As shown in FIG. 4 , the gear box 32 has the driving unit 31 fixed thereto, and accommodates a plurality of driven gears 35 and a driving gear 34 in a rotatable manner.
The gear box 32 has a driven gear accommodating space 32a that accommodates each driven gear 35, a driving gear accommodating space 32b that accommodates the driving gear 34, and a plurality of mounting recesses 32c into which tools 80 can be attached.
The mounting recesses 32c are formed as holes communicating with the driven gear accommodating space 32a in which the driven gears 35C to 35H are respectively accommodated. As shown in Fig. 5, the tool support portions 36d of the driven gears 35C to 35H are located in the mounting recesses 32c.

4, the gear box 32 includes a box body 32d and a lid 32e. The gear box 32 is divided into two members, the box body 32d and the lid 32e, in the direction along the rotation axis I. A boundary surface Sf between the box body 32d and the lid 32e is located at the middle of the drive gear accommodating space 32b and the middle of the driven gear accommodating space 32a.
5, the second helical gear portion 37, the bearing 33b, the shaft portion 36c of the first helical gear portion 36, and the gear body portion 36h are accommodated in the driven gear accommodating space 32a formed in the cover portion 32e. The bearing 33c and the shaft portion 36e of the first helical gear portion 36 are accommodated in the driven gear accommodating space 32a formed in the box body portion 32d.

As shown in FIG. 4, the box body 32d has the above-mentioned multiple mounting recesses 32c. The lid 32e is removably fixed to the box body 32d. When the lid 32e is removed from the box body 32d, the driven gear 35 and the drive gear 34 are exposed, particularly the back surface 37r (see FIG. 5 and FIG. 9) of the second helical gear portion 37 to which the connecting member 38 is detachable, and the back surface of the second helical gear portion 34b to which the connecting member 34c is detachable. When the lid 32e is removed from the box body 32d, as shown in FIG. 9, there are no obstacles around the teeth 36a and 37a of the driven gear 35, making it easier to attach and detach the driven gear 35.

As shown in FIG. 5, the wave washer 39 is provided between each of the bearings 33b, 33c and the inner surface of the driven gear housing space 32a of the gear box 32 in the direction along the rotation axis I. The wave washer 39 is a waved ring plate and is a vibration absorbing part that absorbs vibrations in the direction along the rotation axis I of the driven gear 35.

As shown in FIG. 1, the control unit 300 controls the first spindle unit 10, the second spindle unit 20, the second spindle movement mechanism 25, the tool unit 30, the tool movement mechanism 42, the B-axis rotation mechanism 45, the tool spindle unit 50, and the tool magazine 60. 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.
1, the control unit 300 machines the workpiece W held by the first spindle 11 with a tool 70 attached to the tool spindle unit 50. Next, the control unit 300 moves the second spindle 21 via the second spindle moving mechanism 25 to a position facing the first spindle 11, and transfers the workpiece W from the first spindle 11 to the second spindle 21. Then, the control unit 300 machines the workpiece W held by the second spindle 21 with a tool 80 attached to the tool unit 30, and ejects the machined workpiece W to the outside. This completes the machining process.
When machining a workpiece W with the tool 80 attached to the tool unit 30, the control unit 300 drives the drive unit 31 to rotate the drive gear 34, as shown in Fig. 4. As shown in Fig. 3, the rotation of the drive gear 34 causes the driven gears 35A to 35H to rotate, and the tool 80 attached to the tool support unit 36d rotates together with the driven gears 35C to 35H. Machining is performed by the cutting edge of the rotating tool 80 coming into contact with the workpiece W gripped by the second spindle 21.

Next, a description will be given of a method for assembling the plurality of driven gears 35 and the driving gear 34 into the gear box 32. This assembling operation is performed, for example, by a person.
First, with the cover 32e removed from the gear box 32, the drive unit 31 is attached to the gear box 32, and then the first helical gear portion 34a of the drive gear 34 is attached to the output shaft 31a of the drive unit 31, as shown in Figures 4 and 8. Then, each of the first helical gear portions 36 of the driven gear 35 is attached to the box main body portion 32d in order.
As shown in Figure 5, when attaching the first helical gear portion 36 of the driven gear 35 to the box main body portion 32d, the bearing 33c is accommodated in the driven gear accommodating space 32a formed in the box main body portion 32d, and the shaft portion 36e of the first helical gear portion 36 is inserted into this accommodated bearing 33c.

Next, as shown in FIGS. 4 and 5, the second helical gear portion 34b is attached to the first helical gear portion 34a, and each of the second helical gear portions 37 is attached to each of the first helical gear portions 36 in order.
9, when attaching the second helical gear portion 37 to the first helical gear portion 36, the shaft portion 36c of the first helical gear portion 36 is inserted into the shaft passing hole 37d of the second helical gear portion 37. Then, by relatively rotating the first helical gear portion 36 and the second helical gear portion 37 in the rotational direction C, the positions of the coupling member passing holes 37b, 37c of the second helical gear portion 37 are aligned with the position of the screw hole 36b of the first helical gear portion 36, as shown in FIG.

Next, the first helical gear portions 34a, 36 and the second helical gear portions 34b, 37 are adjusted to mesh with each other. In detail, the gear train 30T is rotated in a state in which the coupling members 34c, 38 are lightly fastened (temporarily fastened) to the first helical gear portions 34a, 36 and the second helical gear portions 34b, 37, whereby the meshing between the first helical gear portions 34a, 36 and the second helical gear portions 34b, 37 is naturally adjusted.
After this adjustment is completed, the second helical gear portions 37 are fixed to the first helical gear portions 36 by the multiple connecting members 38, and the second helical gear portion 34b is fixed to the first helical gear portion 34a by the multiple connecting members 34c. This completes the assembly of the drive gear 34 and the driven gear 35.
Regarding the fastening operation of the coupling member 38, when the head 38a of the coupling member 38 is rotated, the threaded shaft portion 38b of the coupling member 38 passes through the coupling member passing hole 37c of the second helical gear portion 37 and is screwed into the threaded hole 36b of the first helical gear portion 36. The coupling member 34c is also fastened in the same manner as the coupling member 38.

Finally, as shown in FIG. 4, the lid 32e is attached to the box body 32d of the gear box 32. This causes the shaft 36c of the first helical gear 36 to be inserted into the bearing 33b housed in the driven gear housing space 32a formed in the lid 32e. Also, the shaft 34e of the first helical gear 34a is inserted into the bearing 33a housed in the drive gear housing space 32b formed in the lid 32e. This completes the assembly of the multiple driven gears 35 and drive gear 34 to the gear box 32.

10A to 10D, a description will be given of an operation for replacing one specific gear 35X among the plurality of driven gears 35. This operation is performed by, for example, a person.
First, the cover 32e (see FIG. 4) is removed from the gear box 32. Next, as shown in FIG. 10(a), each coupling member 38 is removed from the specific gear 35X, which is the gear to be replaced. This allows the second helical gear portion 37X of the specific gear 35X to be removed from the first helical gear portion 36X of the specific gear 35X, as shown in FIG. 10(b). As shown by the arrow J1 in FIG. 9, the second helical gear portion 37X is pulled out along the rotation axis I away from the first helical gear portion 36X until the second helical gear portion 37X comes out of the shaft portion 36c of the first helical gear portion 36X. This allows the second helical gear portion 37X to be removed from the first helical gear portion 36X.
Next, to remove the first helical gear portion 36X of the specific gear 35X, as shown in Fig. 10(c), the connecting members 34c, 38 are removed from each meshing gear 35Y. The meshing gear 35Y is the driven gear 35 or the driving gear 34 that meshes with the specific gear 35X. Then, similar to the specific gear 35X described above, the second helical gear portion 37Y of the meshing gear 35Y is removed from the first helical gear portion 36Y of the meshing gear 35Y. This removes the specific gear 35X and the second helical gear portions 37X, 37Y of each meshing gear 35Y.
In this state, as shown in Fig. 10(d), the first helical gear portion 36X can be removed from the gear box 32. As shown by the arrow J2 in Fig. 8, the first helical gear portion 36X is removed from the box main body portion 32d by pulling it out along the rotation axis I so as to be away from the box main body portion 32d. This completes the removal of the specific gear 35X.

Next, the installation work of the new specific gear 35X will be described.
The installation work of the new specific gear 35X is performed in the reverse order to the removal work of the specific gear 35X described above. That is, as shown in Figures 10(c) and (d), first, the first helical gear portion 36X is attached to the box body portion 32d so as to be positioned between the first helical gear portions 36Y, and meshed with the first helical gear portions 36Y. Next, as shown in Figures 10(b) and (c), the second helical gear portions 37Y are attached to the first helical gear portions 36Y, and the first helical gear portions 36Y and the second helical gear portions 37Y are connected with the connecting members 34c and 38. Finally, as shown in Figures 10(a) and (b), the second helical gear portion 37X is attached to the first helical gear portion 36X, and the first helical gear portion 36X and the second helical gear portion 37X are connected with the connecting member 38.
This completes the replacement work of the specific gear 35X.

(effect)
According to the embodiment described above, the following effects are achieved.
(1) The gear train 30T includes a driven gear 35, which is an example of a plurality of double helical gears arranged to mesh with each other. The driven gear 35 includes a first helical gear portion 36 and a second helical gear portion 37, which have a plurality of teeth 36a, 37a extending obliquely with respect to a rotation axis I of the driven gear 35 and are formed as separate bodies, and a connecting member 38 that connects the first helical gear portion 36 and the second helical gear portion 37 in a state in which the first helical gear portion 36 and the second helical gear portion 37 are overlapped in a direction along the rotation axis I. The connecting member 38 connects the first helical gear portion 36 and the second helical gear portion 37 in a state in which the positions of the teeth 36a, 37a between the first helical gear portion 36 and the second helical gear portion 37 are shifted in the rotation direction C of the driven gear 35. In addition, when the multiple driven gears 35 are meshed with each other, by removing the connecting member 38 of any one of the multiple driven gears 35, the second helical gear portion 37X of the specific gear 35X can be attached and detached independently from the first helical gear portion 36X.
According to this configuration, it is not necessary to align the teeth 36a, 37a of the first helical gear portion 36 and the second helical gear portion 37 in the rotational direction C. This reduces the effort required for aligning the first helical gear portion 36 and the second helical gear portion 37, facilitating the assembly of the driven gear 35. Furthermore, it is not necessary to prepare a special jig for aligning the first helical gear portion 36 and the second helical gear portion 37.
In addition, in the past, it was necessary to first mesh the multiple double helical gears with each other and then attach them to the gear box. In this regard, with the above-mentioned configuration, when attaching the multiple driven gears 35 to the gear box 32, the second helical gear portion 37 of each driven gear 35 can be attached separately from the first helical gear portion 36, making it easier to assemble the multiple driven gears 35.
In addition, in a conventional double helical gear in which the first helical gear portion and the second helical gear portion are integrated, a groove must be provided between the first helical gear portion and the second helical gear portion to allow the grinding wheel to escape during gear grinding, which makes the double helical gear thick in the axial direction. In this regard, in the above configuration, no groove is required between the first helical gear portion 36 and the second helical gear portion 37, so the driven gear 35 can be made thin.

(2) With the multiple driven gears 35 meshed with each other, the first helical gear portion 36X and the second helical gear portion 37X of the specific gear 35X are configured to be independently detachable and attachable by removing the connecting member 38 of the specific gear 35X and the connecting members 34c, 38 of the meshing gear 35Y meshed with the specific gear 35X.
According to this configuration, the first helical gear portion 36X and the second helical gear portion 37X of the specific gear 35X can be removed independently, so that replacement of any of the specific gears 35X of the multiple driven gears 35 becomes easy.

(3) The first helical gear portion 36 includes a shaft portion 36c extending along the rotation axis I. The second helical gear portion 37 includes a shaft through hole 37d through which the shaft portion 36c is inserted.
According to this configuration, the second helical gear portion 37 can be easily attached to the first helical gear portion 36 by inserting the shaft portion 36c of the first helical gear portion 36 into the shaft passing hole 37d of the second helical gear portion 37. This makes it easy to assemble the driven gear 35.

(4) The gear train 30T includes a gear box 32 that supports a plurality of driven gears 35 rotatably about the rotation axis I. The connecting member 38 is configured to be detachable from a back surface 37r of the second helical gear portion 37 that faces the first helical gear portion 36. The gear box 32 includes a box main body portion 32d that rotatably supports the first helical gear portion 36, and a lid portion 32e that is attached to the box main body portion 32d so as to cover the plurality of driven gears 35 supported by the box main body portion 32d. The lid portion 32e is configured to be detachable from the box main body portion 32d, and exposes the back surface 37r of the second helical gear portion 37 when removed from the box main body portion 32d.
According to this configuration, by removing the cover portion 32e from the gear box 32 and then removing the connecting member 38 from the driven gear 35, the first helical gear portion 36 and the second helical gear portion 37 can be removed independently.

(5) The tool unit 30 has a gear train 30T. The first helical gear portion 36 has the tool support portion 36d that supports the tool 80 rotatably together with the first helical gear portion 36.
According to this configuration, each driven gear 35 is a double helical gear that can rotate more smoothly at high speeds than a spur gear, which improves the machining accuracy and machining power of the tool 80 in the tool unit 30 and facilitates the assembly of each driven gear 35 as described above.

(6) The machine tool 1 includes a tool unit 30 and a second spindle 21 which is an example of a workpiece fixing portion that fixes the workpiece W when the workpiece W is machined by the tool 80 rotated by the tool unit 30.
According to this configuration, the machining accuracy and machining power of the tool 80 in the machine tool 1 can be improved, and the assembly of each driven gear 35 can be facilitated as described above.

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 tool unit 30 is applied to a turning center. However, the tool unit 30 may be applied to any machine tool, such as a machining center, without being limited to a turning center.

In the above embodiment, the machine tool 1 is equipped with a first spindle unit 10 and a second spindle unit 20, but either the first spindle unit 10 or the second spindle unit 20 may be omitted.

The movement directions of the first spindle unit 10, the second spindle unit 20, and the tool spindle unit 50 in the above embodiment can be changed as appropriate. For example, the first spindle unit 10 may be configured to be movable in the Z-axis direction. Also, the tool unit 30 may be configured to be movable.
The number or arrangement of the driven gears 35 in the above embodiment can be changed as appropriate.

Reference Signs List 1...machine tool, 10...first spindle unit, 11...first spindle, 12...first spindle stock, 20...second spindle unit, 21...second spindle, 22...second spindle stock, 25...second spindle movement mechanism, 25S, 42S...slide table, 25X, 42X...X movement mechanism, 25Y, 42Y...Y movement mechanism, 25Z, 42Z...Z movement mechanism, 29...rail, 30...tool unit, 30T...gear train, 31...drive section, 31a...output shaft, 31b, 38a...head, 32...gear box, 32a...driven gear accommodating space, 32b...driving gear accommodating space, 32c...mounting recess, 32d...box main body, 32e...lid, 33a, 33b, 33c...bearing, 34...driving gear, 34a, 36, 36X, 36Y...first 1 helical gear part, 34b, 37, 37X, 37Y... second helical gear part, 34c, 38... coupling member, 34d, 34e, 36c, 36e... shaft part, 34f... recess, 35, 35A to 35H... driven gear, 35X... specific gear, 35Y... meshing gear, 36a, 37a... teeth part, 36b... screw hole, 36d... tool support part, 36h... gear body part, 37b, 37c... coupling member passing hole, 37d... shaft passing hole, 37r... back surface, 38b... screw shaft part, 39... wave washer, 42... tool moving mechanism, 45... B-axis rotation mechanism, 50... tool spindle unit, 60... tool magazine, 70, 80... tool, 300... control part, C... rotation direction, I... rotation axis, S... bed, W... work, Sf... boundary surface

Claims (6)

1. A method for assembling a gear train having a plurality of double helical gears arranged to mesh with one another, comprising the steps of:
The double helical gear is
a first helical gear portion and a second helical gear portion each having a plurality of teeth extending obliquely with respect to a rotation axis of the double helical gear, the first helical gear portion and the second helical gear portion each being formed as separate bodies;
a connecting member that connects the first and second helical gear portions together in a state in which the first and second helical gear portions are overlapped in a direction along the rotation axis,
the connecting member is capable of connecting the first helical gear portion and the second helical gear portion in a temporary connected state that allows relative displacement around a rotation axis,
and an adjustment step of adjusting the meshing between the first helical gear portions and the meshing between the second helical gear portions by operating the gear train in a state in which the first helical gear portion and the second helical gear portion are coupled together in the temporary coupled state by the coupling member when assembling the double helical gear.
How to assemble a gear train. a coupling step of coupling the first helical gear portion and the second helical gear portion, the meshing of which has been adjusted, by the coupling member in a fully coupled state that does not allow relative displacement around a rotation axis , after the adjusting step ;
2. A method for assembling a gear train according to claim 1. A gear train comprising a plurality of double helical gears arranged to mesh with each other,
The double helical gear is
a first helical gear portion and a second helical gear portion each having a plurality of teeth extending obliquely with respect to a rotation axis of the double helical gear, the first helical gear portion and the second helical gear portion each being formed as separate bodies;
a connecting member that connects the first and second helical gear portions together in a state in which the first and second helical gear portions are overlapped in a direction along the rotation axis,
the connecting member allows relative displacement between the first helical gear portion and the second helical gear portion about a rotation axis , and is capable of temporarily connecting the first helical gear portion and the second helical gear portion such that meshing between the first helical gear portions and meshing between the second helical gear portions can be adjusted by the gear train in operation,
the plurality of double helical gears is three or more double helical gears,
When the three or more double helical gears are in mesh with each other, by removing the coupling member of any one of the three or more double helical gears, the second helical gear portion of the specific gear can be independently attached and detached from the first helical gear portion.
Gear train. When the three or more double helical gears are meshed with each other, the first and second helical gear portions of the specific gear are configured to be independently detachable by removing the coupling member of the specific gear and the coupling member of the double helical gear meshed with the specific gear.
The gear train of claim 3. A tool unit having a gear train according to claim 3 or 4 ,
The first helical gear portion includes a tool support portion that supports a tool rotatably together with the first helical gear portion.
Tool unit. A tool unit according to claim 5 ,
A workpiece fixing portion that fixes the workpiece when the workpiece is machined by the tool rotated by the tool unit.
Machine tools.