Gear machining device

Abstract

The present application provides a gear processing device capable of correcting a tooth direction error without using a special tool in a case where a hob is cantilever supported. The gear processing device (1) is provided with: a hob (T) that processes a tooth shape on a workpiece (W); a tool spindle device (33) that cantilever supports the hob (T) so as to be rotatable; a workpiece spindle device (23) that supports the workpiece (W) so as to be rotatable; a drive device (45) that relatively moves the tool spindle device (33) and the workpiece spindle device (23); a measurer (41) that measures a value corresponding to a deflection amount of the hob (T) or a rotational synchronization shift of the workpiece spindle device (23) with respect to the tool spindle device (33); and a correction processing section (43) that corrects an amount of cutting of the hob (T) or the rotational synchronization shift of the workpiece spindle device (23) with respect to the tool spindle device (33) based on the value measured by the measurer (41).

Description

TECHNICAL FIELD

[0001] The present application relates to a gear processing device. BACKGROUND

[0002] In Patent Literature 1, a case is described in which a hob is used to create a processed tooth profile on a workpiece. Here, as the processing of the workpiece proceeds, the load with respect to the rotation of the hob fluctuates due to a change in processing resistance. In particular, the load increases during the start of cutting, stabilizes at a high level during the middle, and decreases during the end of cutting. Therefore, in Patent Literature 1, a case is described in which the fluctuation in the load is electrically detected, a correlation value of the detected signal and a tooth direction error of the workpiece is calculated, and a correction rotation is applied to a workpiece support table based on the correlation value. Thereby, the tooth direction error of the workpiece can be corrected.

[0003] In addition, in Patent Literature 2, a case is described in which a machining center using a replaceable tool is used instead of a hob special machine, and a hob is attached to a tool spindle of the machining center to process a workpiece. In this case, the hob is cantilever supported, so the rigidity of the support of the hob is low. Therefore, the tooth profile processed on the workpiece can have an error with respect to an ideal involute tooth profile. Therefore, in Patent Literature 2, a case is described in which a correction hob having a concave portion or a convex portion formed on an inclined surface of a substantially trapezoidal cutting edge is used to create a tooth profile.

[0004] Patent Literature 1: Japanese Patent Application Publication No. S59-81017

[0005] Patent Literature 2: Japanese Patent Application Publication No. 2015-208806

[0006] However, it is known that in the case where the hob is cantilever supported, the correction described in Patent Literature 1 is not sufficient. That is, it is known that in the case where the hob is cantilever supported, there is a behavior that cannot be represented by only the behavior in which the load increases during the start of cutting, stabilizes at a high level during the middle, and decreases during the end of cutting.

[0007] In addition, the correction hob described in Patent Literature 2 is a special tool, so it becomes high cost. Therefore, a technique is sought in which the tooth direction error is reduced without using a special tool. SUMMARY

[0008] An object of the present application is to provide a gear processing device in which the tooth direction error can be reduced without using a special tool in the case where the hob is cantilever supported.

[0009] A gear processing device includes a hob that processes a tooth profile on a workpiece, a tool spindle device that rotatably cantilever supports the hob, a workpiece spindle device that rotatably supports the workpiece, a drive device that moves the tool spindle device and the workpiece spindle device relative to each other, a measurer that measures a value corresponding to a deflection amount of the hob or a rotation synchronization offset of the workpiece spindle device relative to the tool spindle device, or a tooth phase of the tooth profile of the workpiece, and a correction processing section that corrects an amount of cutting of the hob or the rotation synchronization offset of the workpiece spindle device relative to the tool spindle device based on the value measured by the measurer.

[0010] The inventors have found that, in the case where the hob is cantilever supported, a unique cantilever-induced action occurs. The unique cantilever-induced action refers to an action in which, when a tooth profile is created on a workpiece, the deflection amount of the hob or the vibration of the hob becomes large at the start end of the tooth width direction of the tooth profile and the deflection amount of the hob or the vibration of the hob becomes small at the center of the tooth width direction, due to the fact that the hob is cantilever supported. Moreover, when the unique cantilever-induced action occurs, the correction processing section corrects the amount of cutting or the rotation synchronization offset based on the value corresponding to the deflection amount of the hob or the rotation synchronization offset measured by the measurer. Therefore, tooth direction errors that occur due to the unique cantilever-induced action when the hob is cantilever supported can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a diagram showing one example of a gear processing device.

[0012] Figure 2A is a diagram showing processing using the base end side of the hob.

[0013] Figure 2B is a diagram showing processing using the center portion of the hob.

[0014] Figure 2C is a diagram showing processing using the front end side of the hob.

[0015] Figure 3 is a diagram showing processing using the hob.

[0016] Figure 4A is a diagram showing the locus of the blade portion of the hob relative to the workpiece in an ideal state.

[0017] Figure 4B is a diagram showing the locus of the blade portion of the hob relative to the workpiece when the start end of processing is performed.

[0018] Figure 5A is a diagram showing tooth direction errors in the case where processing is performed using the base end side of the hob.

[0019] Figure 5Bis a graph showing the tooth direction error in a case where the central portion of the hob is used for machining.

[0020] Figure 5C is a graph showing the tooth direction error in a case where the tip end side of the hob is used for machining.

[0021] Figure 6A is a graph showing the change in the Y-axis effective current in a case where the base end side of the hob is used for machining.

[0022] Figure 6B is a graph showing the change in the Y-axis effective current in a case where the central portion of the hob is used for machining.

[0023] Figure 6C is a graph showing the change in the Y-axis effective current in a case where the tip end side of the hob is used for machining.

[0024] Figure 7A is a graph showing the change in the A-axis effective current in a case where the base end side of the hob is used for machining.

[0025] Figure 7B is a graph showing the change in the A-axis effective current in a case where the central portion of the hob is used for machining.

[0026] Figure 7C is a graph showing the change in the A-axis effective current in a case where the tip end side of the hob is used for machining.

[0027] Figure 8 is a functional block diagram showing the gear machining device.

[0028] Figure 9 is a flowchart showing the gear machining method of the first example.

[0029] Figure 10A is a graph showing the trajectory of the blade portion of the hob with respect to the workpiece in a case where the plunge correction is performed.

[0030] Figure 10B is a graph showing the trajectory of the blade portion of the hob with respect to the workpiece in a case where the rotation synchronization correction is performed.

[0031] Figure 11 is a flowchart showing the gear machining method of the second example.

[0032] Figure 12 is a graph showing an example of the workpiece of the third example.

[0033] Figure 13 is a flowchart showing the gear machining method of the third example.

[0034] Explanation of Reference Numerals

[0035] 1: Gear machining device; 10: Base; 20: Workpiece holding device; 21: X-axis moving worktable; 22: B-axis rotary table; 23: Workpiece spindle assembly; 30: Tool holding device; 31: Column; 32: Saddle; 33: Tool spindle assembly; 41: Measuring device; 42: Axial position acquisition unit; 43: Correction processing unit; 44: Control device; 45: Drive device; A, A0, A1; B, B0, B1: Tooth surface; L1: Workpiece machining start end; L2: Workpiece tooth width direction center; L3: Workpiece machining end; T: Hob; W: Workpiece; W1: Major diameter section; W2: Minor diameter section Detailed Implementation

[0036] (1. Structure of gear machining device 1)

[0037] Reference Figure 1 Let me explain the gear machining apparatus 1. The gear machining apparatus 1 is a device that creates machined tooth profiles on the workpiece W by moving the hob T relative to the workpiece W.

[0038] In this example, the gear machining device 1 uses a general-purpose machine tool, such as a machining center. That is, the machining center is configured with interchangeable tools, capable of performing machining corresponding to the installed tools. For example, in addition to the hob T, interchangeable tools include gear cutting tools, end mills, milling tools, drills, turning tools, thread cutting tools, grinding tools, etc. Furthermore, in Figure 1 The tool changer and tool storage cabinet are not shown in the diagram.

[0039] Furthermore, in this example, the machining center of the gear machining apparatus 1 uses a horizontal machining center as its basic structure. However, other structures such as vertical machining centers can be used in the gear machining apparatus 1.

[0040] like Figure 1 As shown, the gear machining device 1, for example, has three mutually orthogonal forward axes (X-axis, Y-axis, and Z-axis) as drive shafts. Here, the direction of the rotation axis of the hob T (which is the same as the rotation axis of the tool spindle) is defined as the Z-axis direction, and the two axes orthogonal to the Z-axis direction are defined as the X-axis direction and the Y-axis direction. Figure 1 In this design, the horizontal direction is designated as the X-axis, and the vertical direction as the Y-axis. Furthermore, the gear machining apparatus 1, as a drive shaft, also has two rotating axes (A-axis and B-axis) for changing the relative posture of the hob T and the workpiece W. Additionally, the gear machining apparatus 1 has a Ct-axis as a rotating axis for rotating the hob T.

[0041] That is, the gear machining device 1 is a 5-axis machining device capable of machining a free curved surface (6-axis machining device if the tool spindle (Ct-axis) is considered). Here, the gear machining device 1 can also be configured to have a Cw-axis (rotational axis around the Z-axis in the reference state) and the B-axis instead of the A-axis (rotational axis around the X-axis in the reference state) and the B-axis, or can be configured to have the A-axis and the Cw-axis.

[0042] In the gear machining device 1, the structure in which the hob T is moved relative to the workpiece W can be appropriately selected. In the present example, the gear machining device 1 enables the hob T to be moved linearly in the Y-axis direction and the Z-axis direction, enables the workpiece W to be moved linearly in the X-axis direction, and enables the workpiece W to be rotated around the A-axis and rotated around the B-axis. In addition, the hob T can be rotated around the Ct-axis.

[0043] The gear machining device 1 includes a base 10, a workpiece holding device 20, and a tool holding device 30. The base 10 is formed in an arbitrary shape such as a substantially rectangular shape, and is disposed on the floor. The workpiece holding device 20 enables the workpiece W to be moved linearly in the X-axis direction, rotated around the A-axis, and rotated around the B-axis relative to the base 10. The workpiece holding device 20 mainly includes an X-axis moving table 21, a B-axis rotating table 22, and a workpiece spindle device 23.

[0044] The X-axis moving table 21 is disposed on the base 10 so as to be movable in the X-axis direction. Specifically, a pair of X-axis rails extending in the X-axis direction (front-rear direction) is provided on the base 10, and the X-axis moving table 21 is driven by a driving device such as a linear motor or a ball screw mechanism, whereby the X-axis moving table 21 is moved reciprocally in the X-axis direction while being guided by the pair of X-axis rails. Figure 1 The B-axis rotating table 22 is disposed on the upper surface of the X-axis moving table 21, and is moved reciprocally in the X-axis direction integrally with the X-axis moving table 21. In addition, the B-axis rotating table 22 is rotatably disposed around the B-axis on the X-axis moving table 21. A rotating motor, not shown, is accommodated in the B-axis rotating table 22, and the B-axis rotating table 22 is driven by the rotating motor so as to be rotatable around the B-axis.

[0045] The workpiece spindle device 23 is disposed on the B-axis rotating table 22 so as to be rotatable around the B-axis integrally with the B-axis rotating table 22. The workpiece spindle device 23 supports the workpiece W so as to be rotatable around the A-axis. In the present example, the workpiece spindle device 23 cantilever supports the workpiece W. The workpiece spindle device 23 includes a rotating motor, not shown, which rotates the workpiece W. In this way, the workpiece holding device 20 enables the workpiece W to be moved in the X-axis direction relative to the base 10, and enables the workpiece W to be rotated around the A-axis and rotated around the B-axis.

[0046]

[0047] ​The tool holding device 30 mainly has a column 31, a saddle 32, and a tool spindle device 33. The column 31 is movably provided to the base 10 in the Z-axis direction. Specifically, a pair of Z-axis rails extending in the Z-axis direction (left-right direction) is provided to the base 10, and the column 31 is driven by a driving device such as a linear motor or a ball screw mechanism (not shown) to be guided by the pair of Z-axis rails and reciprocally move in the Z-axis direction. Figure 1

[0048] The saddle 32 is disposed on the side of the workpiece W (left side) of the column 31 and is parallel to a plane orthogonal to the Z-axis direction. A pair of Y-axis rails extending in the Y-axis direction (up-down direction) is provided to the side of the column 31, and the saddle 32 is driven by a driving device such as a linear motor or a ball screw mechanism (not shown) to reciprocally move in the Y-axis direction. Figure 1 Figure 1

[0049] The tool spindle device 33 is provided to the saddle 32 and integrally moves with the saddle 32 in the Y-axis direction. The tool spindle device 33 supports the hob T so as to be rotatable about the Ct axis. In this example, the tool spindle device 33 cantilever supports the hob T. The tool spindle device 33 has a rotary motor (not shown) that rotates the hob T. In this way, the tool holding device 30 can move the hob T relative to the base 10 in the Y-axis direction and the Z-axis direction and hold the hob T so as to be rotatable about the Ct axis.

[0050] (2. Explanation of the processing state of the hob T)

[0051] The state when creating a tooth profile on the workpiece W with the hob T will be described with reference to Figure 2A - Figure 2C and Figure 3

[0052] As shown in Figure 2A and Figure 3 , the hob T is mounted to the tool spindle device 33 at the base end side (right) and is cantilever supported. In addition, the hob T has a plurality of cutting edge portions on the outer peripheral surface of the tip end side (free end side). The plurality of cutting edge portions are arranged in a helical shape. The plurality of cutting edge portions of the hob T are arranged in a plurality of weeks. That is, the hob T has a plurality of edge rows in the axial direction. The number of edge rows of the hob T in this example is 5 to 6 rows. Figure 2A In the creation processing of the tooth profile, the central axis of the hob T and the central axis of the workpiece W have a crossing angle. In this example, the crossing angle is exemplified as 90°, but it can be set to an angle other than 90°. Furthermore, the hob T is caused to rotate about the central axis thereof, the workpiece W is caused to synchronously rotate about the central axis thereof, and the hob T is caused to relatively move along the central axis of the workpiece W.

[0053]

[0054] ​​​​​In this example, the hob T performs machining on the upper end of the workpiece W as a machining position. That is, the hob T is moved relative to the workpiece W in the X-axis direction and the Z-axis direction while the hob T is positioned in the Y-axis direction, thereby implementing the above-described action. However, the machining position is not limited to the upper end of the workpiece W, and can be set to another position in the circumferential direction of the workpiece W.

[0055] Here, as shown in FIG. 6, the number of blade rows used for machining in the axial direction by the hob T at one time is 2 to 3 rows. That is, the hob T has a larger number of blade rows (5 to 6 rows) than the number of blade rows (2 to 3 rows) used for machining in the axial direction at one time. Therefore, the hob T can perform machining of the workpiece W using the blade rows at different axial positions. Figure 2A Specifically, as shown in FIG. 7, the blade rows at the front end side of the hob T are used to machine the workpiece W.

[0056] As shown in FIG. 8, the blade rows at the central portion of the hob T are used to machine the workpiece W. Figure 2A As shown in FIG. 9, the blade rows at the base end side of the hob T are used to machine the workpiece W. In this way, the hob T can perform machining of the workpiece W using the blade rows at different axial positions, thereby improving the life of the hob T. Figure 2B Figure 2C Here, the hob T is cantilever-supported, so the front end side of the hob T is easily warped. Moreover, the amount of warping of the hob T differs depending on the axial position of the hob T used for machining. The amount of warping of the hob T is largest when machining is performed using the front end side of the hob T as shown in FIG. 6, is next largest when machining is performed using the central portion of the hob T as shown in FIG. 8, and is smallest when machining is performed using the base end side of the hob T as shown in FIG. 9.

[0057] Moreover, in the creation machining of the tooth profile, the machining load changes in sequence. Therefore, the hob T is warped during machining, and the front end side of the hob T vibrates in the direction of warping. Moreover, the magnitude of the vibration of the hob T differs depending on the axial position of the hob T used for machining. The magnitude of the vibration of the hob T is largest when machining is performed using the front end side of the hob T as shown in FIG. 6, is next largest when machining is performed using the central portion of the hob T as shown in FIG. 8, and is smallest when machining is performed using the base end side of the hob T as shown in FIG. 9. That is, the larger the amount of warping of the hob T, the larger the magnitude of the vibration of the hob T. Figure 2A Figure 2B In this way, the hob T is cantilever-supported, thereby generating warping and vibration. The above-described action related to warping and vibration corresponding to the axial position of the hob T used for machining is referred to as a cantilever-induced action. Figure 2C In this way, the hob T is cantilever-supported, thereby generating warping and vibration. The above-described action related to warping and vibration corresponding to the axial position of the hob T used for machining is referred to as a cantilever-induced action.

[0058] Figure 2A In this way, the hob T is cantilever-supported, thereby generating warping and vibration. The above-described action related to warping and vibration corresponding to the axial position of the hob T used for machining is referred to as a cantilever-induced action. Figure 2B Figure 2C In this way, the hob T is cantilever-supported, thereby generating warping and vibration. The above-described action related to warping and vibration corresponding to the axial position of the hob T used for machining is referred to as a cantilever-induced action.

[0059] In this way, the hob T is cantilever-supported, thereby generating warping and vibration. The above-described action related to warping and vibration corresponding to the axial position of the hob T used for machining is referred to as a cantilever-induced action. ​​​​

[0060] (3. Definition of the machining position of workpiece W)

[0061] Reference Figure 3 To define the machining position of workpiece W. For example... Figure 3 As shown, when machining workpiece W using hob T, hob T is rotated, workpiece W is rotated synchronously, and hob T is moved relative to workpiece W along the central axis of workpiece W, thereby creating machining tooth profiles on workpiece W.

[0062] In this example, with the cross angle set to 90°, the hob T is moved along the X-axis. However, with the cross angle tilted from 90°, the hob T is moved in a direction tilted from the X-axis.

[0063] exist Figure 3 The diagram illustrates the state in which the hob T moves relative to the workpiece W from right to left. Here, in the workpiece W, the starting end of machining in the tooth width direction is designated L1, the central portion in the tooth width direction is designated L2, and the ending end of machining in the tooth width direction is designated L3. The actions caused by the cantilever differ at the starting end L1, the central portion in the tooth width direction L2, and the ending end L3. Details will be provided later.

[0064] (4. The trajectory of the cutting edge of the hobbing cutter T)

[0065] Reference Figure 4A as well as Figure 4B To illustrate the trajectory of the cutting edge of the hob T. Figure 4A This represents the ideal state. The hob T is moved relative to the workpiece W, thereby causing the cutting edge of the hob T to move relative to the workpiece W. Figure 4A Move as shown by the hollow arrow. From Figure 4A It cuts in from the upper right and exits from the upper left. At this time, the tooth surface A0 formed on the workpiece W is the tooth surface on the starting side of the cut, and the tooth surface B0 is the tooth surface on the ending side of the cut.

[0066] However, as mentioned above, the hob T experiences cantilevering during machining, causing movement. That is, the hob T warps and vibrates. Figure 4B As shown by the black arrow, the cutting edge of the hob T warps and vibrates when machining the tooth surface on the starting side of the cut.

[0067] In this way, the cutting edge of the hob T is used to machine the tooth surface on the side where the cutting begins ( Figure 4B When the right tooth surface is (the direction of the reverse cutting direction from the ideal tooth surface A0), it is located in the direction of the reverse cutting direction. Figure 4B The position offset to the left of the tooth surface. Therefore, the tooth surface on the starting side of the cut has cutting residue relative to the ideal tooth surface A0, with a positive tooth direction error.

[0068] On the other hand, the cutting edge of the hob T is used to machine the tooth surface on the end of the cutting inlet side.Figure 4B the left side of the ideal tooth surface B0 toward the cutting-in direction (the left side of the tooth surface A) is offset. The hob T maintains the offset that occurs when the tooth surface on the cutting-in start side is machined, so becomes in this state. That is, the tooth surface on the cutting-in end side becomes overcut with respect to the ideal tooth surface B0, and has a negative tooth direction error. Figure 4B

[0069] (5. Machining accuracy of the workpiece W and state of the gear machining device 1 at the time of machining)

[0070] In the case where the machining positions of the hob T are set to Figure 2A , Figure 2B , Figure 2C respectively, the machining accuracy of the workpiece W, that is, the tooth direction error will be explained. Figure 5A , Figure 5B , Figure 5C Figure 5A - Figure 5C corresponds to Figure 2A - Figure 2C .

[0071] In the drawings, the up-and-down direction is the tooth direction of the teeth of the workpiece W that are machined. Also, in Figure 5A - Figure 5C , the right drawing shows the tooth surface A on the cutting-in start side of the right side of Figure 4A , Figure 4B , and A0 shows the ideal tooth surface. Here, the ideal tooth surface A0 in this tooth surface A is the position that is cut deepest.

[0072] Also, in Figure 5A - Figure 5C , the left drawing shows the tooth surface B on the cutting-in end side of the left side of Figure 4A , Figure 4B , and B0 shows the ideal tooth surface. The ideal tooth surface B0 is the position in the case where the ideal tooth surface A0 of the tooth surface A on the cutting-in start side is the reference. Also, the machining start position in the workpiece W is set to Ms, and the machining end position is set to Me. That is, in the drawing, machining proceeds from the lower side to the upper side.

[0073] As shown in Figure 5A , in the case where the axial position of the hob T used for machining is the front end side, the tooth surface A on the right side has a positive tooth direction error when machining the machining start end portion L1 (shown in Figure 3 ) of the workpiece W and the machining end end portion L3 of the workpiece W. That is, cutting residue occurs. The tooth surface A on the right side has a slight positive tooth direction error when machining the central portion L2 of the workpiece W in the tooth width direction, but is close to the ideal tooth surface A0.

[0074] ​​On the other hand, the left-hand tooth surface B has a negative tooth trace error at the machining start end portion LI of the workpiece W and at the machining end end portion L3 of the workpiece W. The left-hand tooth surface B has a slightly negative tooth trace error when machining the central portion L2 of the workpiece W in the tooth width direction of the workpiece W, but is close to the ideal tooth surface BO.

[0075] As shown in Figure 5B and Figure 5C , even when the axial position of the hob T used for machining is the central portion and the base end side, the same tendency as in the case of the tip end side is exhibited. However, the size of the tooth trace error is largest when the axial position of the hob T used for machining is the tip end side, is next largest when the axial position of the hob T used for machining is the central portion, and is smallest when the axial position of the hob T used for machining is the base end side. In addition, if the machining of the machining start end portion LI of the workpiece W is compared with the machining of the machining end end portion L3 of the workpiece W, the machining of the machining start end portion LI of the workpiece W has a tendency to have a large tooth trace error.

[0076] Next, the behavior of the effective current in the drive device that moves the saddle 32 with respect to the column 31 in the Y-axis direction, i.e., the Y-axis drive device, will be described with reference to Figure 6A - Figure 6C . Figure 6A - Figure 6C Corresponds to Figure 2A - Figure 2C .

[0077] In the drawing, the machining start time is set to Ts, and the machining end time is set to Te. In addition, the time for machining the machining start end portion LI of the workpiece W shown in Figure 3 is set to Tl, the time for machining the central portion L2 of the workpiece W in the tooth width direction is set to T2, and the time for machining the machining end end portion L3 of the workpiece W is set to T3.

[0078] Here, the variation in the Y-axis effective current is related to the size of the vibration in the Y-axis direction caused by the hob T. That is, the larger the variation in the Y-axis effective current, the larger the vibration of the hob T in the Y-axis direction. In the case where the behavior is independent of the mechanical structure, the Y-axis effective current here is the drive current of the drive device in the direction orthogonal to the center line of rotation of the hob T, and corresponds to the vibration of the tool spindle device 33 in the direction orthogonal to the center line of rotation of the hob T.

[0079] As shown in Figure 6AAs shown, when the axial position of the hob T used for machining is at the front end, the effective Y-axis current varies greatly when machining the starting end L1 of the workpiece W (time T1). Furthermore, when machining the central portion L2 of the workpiece W in the tooth width direction (time T2), the variation in the effective Y-axis current is smaller compared to when machining the starting end L1. Additionally, when machining the ending end L3 of the workpiece W (time T3), the variation in the effective Y-axis current is smaller than when machining the starting end L1, but larger than when machining the central portion L2 in the tooth width direction.

[0080] like Figure 6B as well as Figure 6C As shown, even when the axial position of the hob T used for machining is at the center or base end, the trend is the same as when it is at the front end. However, the magnitude of the variation in the effective Y-axis current is greatest when the axial position of the hob T used for machining is at the front end, followed by the center, and smallest at the base end. Furthermore, comparing machining the workpiece W at the starting end L1 with machining the workpiece W at the ending end L3, the latter tends to have a larger variation in the effective Y-axis current.

[0081] In addition, based on Figure 6A - Figure 6C The magnitude of the variation in the effective current along the Y-axis is Figure 6A The axial position of the hob T shown is maximum when it is at the front end. Figure 6B The axial position shown is the second largest in the case of the central part. Figure 6C The axial position shown is the minimum when the axial position is at the base. That is, the magnitude of the variation in the effective current along the Y-axis tends to be larger as the axial position moves from the base towards the front end.

[0082] Next, refer to Figure 7A - Figure 7C To explain the action of the effective current of the drive device of the A-axis, namely the motor that drives the workpiece W to rotate in the workpiece spindle device 23. Figure 7A - Figure 7C and Figure 2A - Figure 2C correspond.

[0083] In the diagram, the machining start time is set to Ts, and the machining end time is set to Te. Additionally, Figure 3 The time for machining the starting end L1 of the workpiece W is set as T1, the time for machining the central part L2 of the workpiece W in the tooth width direction is set as T2, and the time for machining the ending end L3 of the workpiece W is set as T3.

[0084] Here, the variation in the effective current of the A-axis is related to the offset of the rotation direction of the workpiece W (rotational synchronization offset) when the hob T is used to machine the workpiece W. That is, the greater the variation in the effective current of the A-axis, the greater the synchronization offset between the rotation of the hob T and the rotation of the workpiece W.

[0085] like Figure 7A As shown, when the axial position of the hob T used for machining is at the front end, the effective A-axis current varies greatly when machining the starting end L1 of the workpiece W (time T1). Furthermore, when machining the central portion L2 of the workpiece W in the tooth width direction (time T2), the variation in the effective A-axis current is smaller compared to when machining the starting end L1. Additionally, when machining the ending end L3 of the workpiece W (time T3), the variation in the effective A-axis current is smaller than when machining the starting end L1, but larger than when machining the central portion L2 in the tooth width direction.

[0086] like Figure 7B as well as Figure 7C As shown, even when the axial position of the hob T used for machining is at the center or base end, the trend is the same as that at the front end. However, the magnitude of the variation in the effective A-axis current is greatest when the axial position of the hob T used for machining is at the front end, followed by the center, and smallest at the base end. Furthermore, comparing machining the workpiece W at the starting end L1 with machining the workpiece W at the ending end L3, the one where machining the workpiece W at the starting end L1 tends to have a larger variation in the effective A-axis current.

[0087] As described above, when machining the starting end L1 of workpiece W, compared to machining the central part L2, the tooth direction error, the variation in effective Y-axis current, and the variation in effective A-axis current all increase. Furthermore, when machining the ending end L3 of workpiece W, compared to machining the central part L2, the tooth direction error, the variation in effective Y-axis current, and the variation in effective A-axis current all increase.

[0088] Furthermore, compared to machining using the central part and base end of the hob T, machining using the front end side results in larger tooth direction errors, variations in the effective current of the Y-axis, and variations in the effective current of the A-axis.

[0089] That is, it can be said that the magnitude of the variation of the Y-axis effective current and the magnitude of the variation of the A-axis effective current represent values equivalent to the tooth direction error. Also, the magnitude of the variation of the Y-axis effective current becomes a value equivalent to the amount of warping of the hob T, and the magnitude of the variation of the A-axis effective current becomes a value equivalent to the rotational synchronous offset of the workpiece spindle device 23 with respect to the tool spindle device 33.

[0090] (6. Functional module structure of the gear processing device 1)

[0091] The functional module structure of the gear processing device 1 will be described with reference to Figure 8 FIG. 6. An example of the mechanical configuration of the gear processing device 1 is shown in Figure 1 Here, the functional structure of the gear processing device 1 will be described.

[0092] The gear processing device 1 is provided with at least a measurer 41, an axial position acquisition section 42, a correction processing section 43, a control device 44, and a driving device 45. The measurer 41 is a measurer that measures a value equivalent to the amount of warping of the hob T when a cantilever-induced action is generated, a measurer that measures a value equivalent to the rotational synchronous offset of the workpiece spindle device 23 with respect to the tool spindle device 33, or a measurer that measures the rotational position of the tooth profile created on the workpiece W, i.e., the tooth phase.

[0093] For example, the measurer 41 can apply a sensor that measures the effective current of the Y-axis driving motor as a value equivalent to the amount of warping of the hob T. The measurer 41 can apply a sensor that measures the effective current of the A-axis driving motor as a value equivalent to the rotational synchronous offset of the workpiece spindle device 23 with respect to the tool spindle device 33. In addition, the measurer 41 can apply a device that acquires the synchronous offset information of the driving motor of the A-axis and the driving motor of the Ct-axis as a value equivalent to the rotational synchronous offset, if the synchronous offset information can be acquired. In addition, the measurer 41 can acquire the value of the rotational angle sensor of the A-axis driving motor and the value of the rotational angle sensor of the driving motor of the Ct-axis, and thereby calculate the rotational synchronous offset using the angle difference of the motors and the like. In addition, the measurer 41 can be a displacement sensor that can directly measure the amount of warping of the hob T. Also, the measurer 41 can apply, for example, an eddy current sensor, an electromagnetic pickup, a laser sensor, and the like that measure the distance to the addendum surface and the dedendum surface as a value equivalent to the tooth phase of the tooth profile created on the workpiece W.

[0094] In this example, the workpiece W has less warping and vibration compared to the hob T. Therefore, the warping of the workpiece W can be disregarded. However, it is also possible to consider the case where the workpiece W warps in the same way as the hob T. That is, since the workpiece W is cantilevered, it generates a cantilever-induced motion similar to the hob T. In this case, the measuring device 41 may include, in addition to the above-described case, a measuring device that measures a value equivalent to the warping of the workpiece W, or a measuring device that measures a value equivalent to the rotational synchronization offset of the workpiece W.

[0095] like Figure 2A - Figure 2C As shown, the axial position acquisition unit 42 acquires the axial position of the hob T used for machining. This axial position can be obtained from the command value (NC program). Specifically, the axial position acquisition unit 42 acquires the axial position of the hob T used for machining as the front end side, the center side, or the base end side. Furthermore, although the axial position acquisition unit 42 acquires three of the above positions (front end side, center side, base end side), it can acquire two positions, or even four or more positions. In addition, the axial position acquisition unit 42 can use a position sensor that can measure the Z-axis movement motor, a linear gauge (linear scale) for the linear position of the Z-axis, etc., for position acquisition. Furthermore, the axial position acquisition unit 42 also measures and acquires the positions of the X-axis and Y-axis in the same way.

[0096] The correction processing unit 43 performs corrections based on the values ​​measured by the measuring device 41 and the axial position of the hob T used for machining, obtained by the axial position acquisition unit 42. For example, the correction processing unit 43 can correct the depth of cut of the hob T, and it can also correct the rotational synchronization offset of the workpiece spindle assembly 23 relative to the tool spindle assembly 33. Furthermore, when multiple tooth profiles are machined on the workpiece W, it can also correct the offset of the tooth phase of the target tooth profile among the multiple tooth profiles relative to the tooth phase of the reference tooth profile among the multiple tooth profiles.

[0097] The correction processing unit 43 needs to determine the cutting amount or rotational synchronization offset as the correction amount. A mapping table showing the relationship between the measurement results of the measuring instrument 41 and the correction amount is created in advance based on past actual results, and the correction amount can be determined using this mapping table.

[0098] Alternatively, the correction amount can also be determined using machine learning. In this case, machine learning is used during the learning phase to generate a fully learned model representing the relationship between the measurement result and the correction amount, and this fully learned model and the value measured by the measuring instrument 41 are used to determine the correction amount during the inference phase.

[0099] The correction amount is determined in a manner that reduces the tooth direction error of the workpiece W. For example, a correction amount can be set that changes the position of the hob T at the machining start end portion LI and the machining end end portion L3 in the tooth width direction. Alternatively, a correction amount can be set that changes the position of the hob T at the central portion L2 in the tooth width direction. Furthermore, the correction amount becomes a value that differs depending on the axial position of the hob T used for machining.

[0100] The control device 44 controls the drive device 45 based on the command value (NC program) and the result corrected by the correction processing portion 43. That is, the control device 44 controls the drive device 45 in a manner that reduces the tooth direction error of the workpiece W by correction.

[0101] Furthermore, the correction processing portion 43 and the control device 44 can be provided as an embedded system of a PLC (Programmable Logic Controller), a CNC (Computerized Numerical Control) device, or the like, or can be provided as a personal computer, a server, or the like, and can be provided with a microcomputer (Microcomputer, Processor), a storage device, or the like, and can perform only control and processing.

[0102] The drive device 45 is a device that moves the tool spindle device 33 relative to the workpiece spindle device 23. In this example, the drive device 45 includes a drive device that linearly drives the X-axis moving table 21, a drive device that rotationally drives the B-axis rotating table 22, a drive device that rotationally drives the workpiece W on the workpiece spindle device 23, a drive device that linearly drives the column 31, a drive device that linearly drives the saddle 32, and a drive device that rotationally drives the hob T on the tool spindle device 33.

[0103] (7. Gear machining method of the first example)

[0104] Referring to Figure 9 , Figure 10A , Figure 10B , a gear machining method of the first example using the gear machining device 1 will be described. In this example, trial machining is performed, and a correction amount is determined using a measured value at the time of trial machining, and machining is performed while correction is performed at the time of actual machining.

[0105] As Figure 9As shown, first, trial machining is started by the control device 44 (step Sl). The trial machining is machining of the trial workpiece W. Next, during the trial machining, measurement is performed by the measurer 41 (step S2). Further, before the trial machining ends, the measurement is continued (step S3: No). If the trial machining ends (S3: Yes), the correction amount is decided by the correction processing section 43 based on the measurement value measured by the measurer 41 during the trial machining (step S4). The decision of the correction amount can use the map table generated in advance as described above, or can use machine learning.

[0106] Next, the control device 44 starts actual machining (step S5). The actual machining is machining of an actual workpiece W different from the trial workpiece W. The control device 44 performs correction control based on the correction amount in the actual machining (step S6). Then, before the actual machining ends, the correction control is continued (step S7: No). If the actual machining ends (S7: Yes), the processing ends.

[0107] Here, as the method of correction, two kinds are exemplified. As shown in FIG. 6, the first correction method is a method of correcting the amount of cut-in. That is, in the tooth width direction of the workpiece W, the amount of cut-in of the machining start end portion LI and the machining end end portion L3 (the amount of cut-in in the Y-axis direction in this example) is made larger than the command value. In the central portion L2 of the tooth width direction of the workpiece W, the amount of cut-in is the same value as the command value. Figure 10A In the case shown in FIG. 6, Al and Bl are tooth surfaces machined using the corrected command value in the case where there is no warping and vibration of the hob T. Even if the hob T is warped and vibrated due to the machining load generated at the machining start end portion LI of the tooth width direction of the workpiece W, it is possible to form the ideal tooth surfaces A0, B0 by correction of the amount of cut-in.

[0108] Figure 10A In the case shown in FIG. 7, Al and Bl are tooth surfaces machined using the corrected command value in the case where there is no warping and vibration of the hob T. Even if the hob T is warped and vibrated due to the machining load generated at the machining start end portion LI of the tooth width direction of the workpiece W, it is possible to form the ideal tooth surfaces A0, B0 by correction of the amount of cut-in.

[0109] In addition, as shown in FIG. 8, the second correction method corrects the rotational synchronization of the workpiece spindle device 23 with respect to the tool spindle device 33. That is, in the tooth width direction of the workpiece W, the rotational synchronization of the machining start end portion LI and the machining end end portion L3 is offset. In the case shown in FIG. 8, Al and Bl are tooth surfaces machined using the corrected command value in the case where there is no warping and vibration of the hob T. Even if the hob T is warped and vibrated due to the machining load generated at the machining start end portion LI of the tooth width direction of the workpiece W, it is possible to form the ideal tooth surfaces A0, B0 by correction of the rotational synchronization offset. Figure 10B Figure 10B In the case shown in FIG. 8, Al and Bl are tooth surfaces machined using the corrected command value in the case where there is no warping and vibration of the hob T. Even if the hob T is warped and vibrated due to the machining load generated at the machining start end portion LI of the tooth width direction of the workpiece W, it is possible to form the ideal tooth surfaces A0, B0 by correction of the rotational synchronization offset.

[0110] ​​As described above, when the hob T produces a unique cantilever-induced movement, the correction processing unit 43 corrects the cut amount or rotational synchronization offset based on a value corresponding to the warpage or rotational synchronization offset of the hob T measured by the measuring device 41. Therefore, it is possible to reduce the tooth direction error caused by the unique cantilever-induced movement when the hob T is supported by a cantilever.

[0111] (8. Gear machining method in the second example)

[0112] Reference Figure 11 The following describes a second example of a gear machining method using gear machining apparatus 1. In this example, the correction amount is determined at the initial stage of actual machining without trial machining, and machining is performed simultaneously with the correction during subsequent machining.

[0113] like Figure 11 As shown, the machining start point L1 of workpiece W (the actual workpiece) is initiated by control device 44. Figure 3 The machining of the workpiece W is shown in the figure. (Step S11). Next, during the machining of the workpiece W at the starting end L1, the measurement is performed by the measuring device 41 (Step S12). The measurement continues until the machining of the starting end L1 is completed (Step S13: No).

[0114] If the machining of the machining start end L1 is completed (S13: Yes), the correction processing unit 43 determines the correction amount based on the measurement value measured by the measuring device 41 during the machining of the machining start end L1 (step S14). The determination of the correction amount can be applied to the two methods described in the first correction method.

[0115] Next, machining of the central portion L2 in the tooth width direction of workpiece W begins (step S15). During the machining of the central portion L2, the control device 44 performs correction control based on the correction amount (step S16). Furthermore, correction control continues until machining ends, that is, until machining ends at the machining end L3 of workpiece W (step S17: No). If machining ends (S17: Yes), the process ends.

[0116] Here, in the tooth width direction of workpiece W, if correction control is suddenly implemented based on the correction amount at the moment of moving from the machining start end L1 to the central part L2, a step may form on the tooth surface of workpiece W. Therefore, immediately after the transition from non-correction control to correction control, the influence ratio of the correction amount can be gradually increased. As a result, the negative impact caused by the start of correction control can be suppressed.

[0117] As described above, it is possible to reduce tooth direction errors caused by the cantilever, which is unique to hobs T when they are supported by a cantilever. Furthermore, since trial machining is not required, the generation of unwanted workpieces W can be prevented.

[0118] (9. Gear machining method in the third example)

[0119] Reference Figure 12 as well as Figure 13 This example illustrates a gear machining method using gear machining apparatus 1 in a third instance. In this example, as... Figure 12 As shown, workpiece W has a large diameter portion W1 and a small diameter portion W2. A gear tooth profile is created relative to the large diameter portion W1 and the small diameter portion W2 using the gear machining method of either the first or second example. That is, workpiece W in this example is a stepped gear. Furthermore, in this example, the measuring device 41 measures the tooth phase for the teeth created in the large diameter portion W1 (serving as a reference tooth profile for finishing) and the teeth created in the small diameter portion W2 (serving as a correction target tooth profile for semi-finishing). The correction processing unit 43 calculates the correction amount for correcting the tooth phase offset during the finishing of the small diameter portion W2.

[0120] like Figure 13 As shown, the measuring device 41 detects the tooth phase of the large-diameter portion W1, which serves as the reference tooth profile (step S21). Next, the measuring device 41 detects the tooth phase of the small-diameter portion W2, which serves as the tooth profile to be corrected (step S22). Next, the correction processing unit 43 calculates the offset D between the tooth phases of the large-diameter portion W1 and the small-diameter portion W2 (step S23).

[0121] Next, the offset D calculated by the correction processing unit 43 is compared with the pre-stored main offset DB (step S24). Then, if the offset D is less than the main offset DB (step S24: No), the phase difference between the large diameter part W1 and the small diameter part W2 is within the allowable range, and it is not necessary to correct the phase difference between the small diameter part W2 and the large diameter part W1.

[0122] On the other hand, if the offset D is greater than the main offset DB (step S24: Yes), the phase difference between the large-diameter portion W1 and the small-diameter portion W2 is outside the allowable range, so it is necessary to correct the phase difference between the small-diameter portion W2 and the large-diameter portion W1. Therefore, the correction processing unit 43 calculates the correction amount M for correcting the phase difference between the small-diameter portion W2 and the large-diameter portion W1 (step S25). Here, the correction processing unit 43 determines the correction amount M by setting the offset D to be less than or equal to the main offset DB, for example, by setting the difference between the offset D and the main offset DB.

[0123] Next, the control device 44 rotates the workpiece spindle assembly 23 based on the correction amount M (step S26). Here, the control device 44 rotates the workpiece spindle assembly 23 in the direction where the offset amount D decreases based on the correction amount M.

[0124] As described above, the tooth direction error caused by the action of the cantilever due to the cantilever support of the hob T can be reduced. In addition, in the case where a plurality of tooth profiles are created on the workpiece W, the small-diameter portion W2 is finally finished with the finish machining in a state where the tooth phase of the small-diameter portion W2 as the correction target tooth profile is corrected with respect to the tooth phase of the large-diameter portion W1 as the reference tooth profile, so the machining accuracy of the workpiece W can be improved.

Claims

1. A gear processing apparatus characterized by comprising: Possessing: a hob that processes a tooth profile on a workpiece; a tool spindle device that rotatably cantilever supports the above-mentioned hob; a workpiece spindle device that rotatably supports the above-mentioned workpiece; a drive device that moves the above-mentioned tool spindle device and the above-mentioned workpiece spindle device relative to each other; a measurer that measures a value corresponding to the amount of warping of the above-mentioned hob, the rotational synchronization offset of the above-mentioned workpiece spindle device relative to the above-mentioned tool spindle device, or the tooth phase of the tooth profile of the above-mentioned workpiece; and a correction processing section that corrects the amount of cutting of the above-mentioned hob or the rotational synchronization offset of the above-mentioned workpiece spindle device relative to the above-mentioned tool spindle device based on the above-mentioned value measured by the above-mentioned measurer, the above-mentioned measurer measures the drive current of the rotational motor of the above-mentioned tool spindle device, the drive current of the rotational motor of the above-mentioned workpiece spindle device, and the rotational synchronization offset of the rotational motor of the above-mentioned tool spindle device and the rotational motor of the above-mentioned workpiece spindle device as the above-mentioned value corresponding to the amount of warping of the above-mentioned hob or the rotational synchronization offset of the above-mentioned workpiece spindle device relative to the above-mentioned tool spindle device.

2. The gear processing device according to claim 1, characterized in that: the above-mentioned workpiece spindle device cantilever supports the above-mentioned workpiece, the above-mentioned hob is cantilever supported and the above-mentioned workpiece is cantilever supported, and the above-mentioned tooth profile is created on the above-mentioned workpiece.

3. The gear processing device according to claim 1 or 2, characterized in that: the above-mentioned hob has a larger number of blade rows in the axial direction than the number of blade rows used in one processing, the above-mentioned correction processing section corrects based on the above-mentioned value measured by the above-mentioned measurer and the axial position of the above-mentioned hob used for processing.

4. The gear processing device according to claim 1 or 2, characterized in that: the above-mentioned correction processing section decides the correction amount based on the above-mentioned value measured by the above-mentioned measurer when processing a test workpiece, and corrects based on the decided above-mentioned correction amount when processing an actual workpiece different from the above-mentioned test workpiece.

5. The gear processing device according to claim 3, characterized in that: the above-mentioned correction processing section decides the correction amount based on the above-mentioned value measured by the above-mentioned measurer when processing a test workpiece, and corrects based on the decided above-mentioned correction amount when processing an actual workpiece different from the above-mentioned test workpiece.

6. A gear machining apparatus characterized by comprising: Possessing: a hob that processes a tooth profile on a workpiece; a tool spindle device that rotatably cantilever supports the above-mentioned hob; a workpiece spindle device that rotatably supports the above-mentioned workpiece; a drive device that moves the above-mentioned tool spindle device and the above-mentioned workpiece spindle device relative to each other; a measurer that measures a value corresponding to the amount of warping of the above-mentioned hob, the rotational synchronization offset of the above-mentioned workpiece spindle device relative to the above-mentioned tool spindle device, or the tooth phase of the tooth profile of the above-mentioned workpiece; and a correction processing section that corrects the amount of cutting of the above-mentioned hob or the rotational synchronization offset of the above-mentioned workpiece spindle device relative to the above-mentioned tool spindle device based on the above-mentioned value measured by the above-mentioned measurer, The correction processing section determines a correction amount based on the value measured by the measurer when machining the tooth width direction start end portion of the actual workpiece, and corrects based on the determined correction amount when machining the tooth width direction center portion of the actual workpiece.

7. The gear machining device according to claim 6, wherein The correction processing section corrects based on the determined correction amount when machining the tooth width direction center portion and the end portion of the workpiece.

8. A gear machining apparatus characterized by comprising: Provided are: a hob that machines a tooth profile on a workpiece; a tool spindle device that rotatably cantilever supports the hob; a workpiece spindle device that rotatably supports the workpiece; a drive device that relatively moves the tool spindle device and the workpiece spindle device; a measurer that measures a value corresponding to a deflection amount of the hob, a rotational synchronization offset of the workpiece spindle device relative to the tool spindle device, or a tooth phase of the tooth profile of the workpiece; and a correction processing section that corrects a cutting amount of the hob or a rotational synchronization offset of the workpiece spindle device relative to the tool spindle device based on the value measured by the measurer, the workpiece is a workpiece that machines a plurality of tooth profiles, the measurer measures a tooth phase of a reference tooth profile that is a tooth profile to be finish machined among the plurality of tooth profiles, and a tooth phase of a correction target tooth profile that is a tooth profile to be semi-finish machined among the plurality of tooth profiles, the correction processing section determines a correction amount based on an offset of the tooth phase of the correction target tooth profile relative to the tooth phase of the reference tooth profile, and corrects the offset of the tooth phase when the correction target tooth profile is finish machined.

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