JP7395868B2 - Gear processing equipment and gear processing method - Google Patents

Description

The present invention relates to a gear processing device and a gear processing method.

In machine tools, when the relative rotational speed between the cutting tool and the workpiece is increased or the depth of cut is increased, chatter vibration is likely to occur in the workpiece. Therefore, for example, Patent Document 1 describes a technique in which the dynamic strain of the workpiece is determined, and the chatter vibration of the workpiece is determined based on the magnitude of the dynamic strain, and the workpiece is machined. There is. Patent Document 2 describes a technology for machining a workpiece while preventing chatter vibration of the workpiece by rotating the cutting tool at a rotation speed at which the natural vibration of the workpiece and the vibration component of the cutting tool do not resonate. is listed.

Patent Document 3 describes a technique for machining a workpiece while preventing the occurrence of chatter vibration of the workpiece by rotating the workpiece or cutting tool by inertia rotation and relatively feeding the cutting tool and the workpiece. has been done. Patent Document 4 describes a technique for machining a workpiece while preventing chatter vibration of the workpiece by reducing the depth of cut of a cutting tool into the workpiece. However, it is unclear whether each of the above-mentioned techniques is applicable to a gear processing device (gear processing method) that processes a gear on a workpiece by skiving.

The present inventor has discovered a technique (Patent Document 5) for processing a gear on a workpiece by suppressing chatter vibration of the workpiece in a gear processing apparatus (gear processing method) that performs skiving processing. That is, Patent Document 5 discloses that while the rotational speeds of the workpiece spindle (workpiece) and tool spindle (gear cutting tool) are varied and rotated synchronously, the gear cutting tool is moved against the workpiece in the direction of the rotational axis of the workpiece. A technique is described for machining a gear on a workpiece by suppressing chatter vibration of the workpiece by moving the gear relative to the workpiece.

Japanese Patent Application Publication No. 2000-237932 Japanese Patent Application Publication No. 2009-274179 Japanese Unexamined Patent Publication No. 127801/1983 Patent No. 5929065 Japanese Patent Application Publication No. 2018-62056

In the above-mentioned gear processing apparatus, when varying the rotation speeds of the workpiece spindle and the tool spindle, a rotational phase synchronization error between the workpiece spindle and the tool spindle may occur. In that case, waviness may occur in the tooth traces of the teeth of the gear to be machined, and there is a risk that gear machining accuracy may deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gear machining device and a gear machining method that can easily grasp the rotational phase synchronization error between a workpiece spindle and a tool spindle before starting gear machining.

The gear machining device of the present invention moves the gear cutting tool relative to the workpiece in the direction of the rotational axis of the workpiece while rotating the workpiece and the gear cutting tool synchronously. A gear processing device for machining gear teeth, comprising: a workpiece spindle that rotatably supports the workpiece; a rotatable tool spindle on which the gear cutting tool is mounted; and a rotational speed of the workpiece spindle. a workpiece spindle rotational speed control section that varies the rotational speed of the tool spindle; a tool spindle rotational speed control section that varies the rotational speed of the tool spindle; a first moment of inertia of a first rotating body including the workpiece; When a rotational phase synchronization error between the workpiece spindle and the tool spindle occurs due to a difference in the second moments of inertia of the two rotating bodies, the workpiece spindle rotational phase of the workpiece spindle and the tool spindle of the tool spindle a phase error calculation unit that calculates the rotational phase synchronization error based on the rotational phase; and a tooth trace of the teeth of the gear machined on the workpiece based on the rotational phase synchronization error calculated by the phase error calculation unit. A tooth trace error calculation unit that calculates an error .

The gear machining method of the present invention provides the gear cutting method in the direction of the rotational axis of the workpiece while synchronously rotating a workpiece spindle that rotatably supports the workpiece and a rotatable tool spindle on which a gear cutting tool is attached. A gear machining method for machining gear teeth on the workpiece by moving a tool relative to the workpiece, the method comprising: a rotational speed variation step of varying the rotational speeds of the workpiece spindle and the tool spindle; , a rotation phase input step of simultaneously inputting a workpiece spindle rotation phase of the workpiece spindle and a tool spindle rotation phase of the tool spindle during the variation of the rotational speed; and a first rotating body including the workpiece. When a rotational phase synchronization error between the workpiece spindle and the tool spindle occurs due to a difference between the first moment of inertia of the second rotating body including the gear cutting tool, the workpiece spindle a phase error calculation step of calculating the rotational phase synchronization error based on the workpiece spindle rotational phase and the tool spindle rotational phase of the tool spindle, and based on the rotational phase synchronization error calculated in the phase error calculation step, A tooth trace error calculation step of calculating a tooth trace error of teeth of the gear to be machined on the workpiece .

According to the gear processing apparatus and gear processing method of the present invention, focusing on the first moment of inertia of the first rotating body including the workpiece and the inertia moment of the second rotating body including the gear cutting tool, the first and second moments of inertia are When there is a difference in moment, the rotational phase synchronization error that occurs between the workpiece spindle and the tool spindle is calculated based on the workpiece spindle rotation phase of the workpiece spindle and the tool spindle rotation phase of the tool spindle. As a result, it is possible to easily grasp the rotational phase synchronization error between the workpiece spindle and the tool spindle before starting gear machining.

1 is a perspective view of a gear processing device in an embodiment of the present invention. FIG. 2 is an enlarged partial cross-sectional view of the gear cutting tool when performing skiving processing in the first embodiment. FIG. 2 is a block diagram of a control device for a gear processing device. It is a flowchart of the first half of gear processing processing performed by a control device. It is a flowchart of the latter half of gear processing processing performed by a control device. It is a figure which shows the operation|movement of the gear cutting tool and workpiece at the time of skiving processing in 1st embodiment. It is a graph when the rotational speed of the workpiece spindle controlled by the control device is varied in a sine wave. 7 is a graph showing fluctuations in the rotational phase synchronization error between the workpiece spindle and the tool spindle when the rotational speed of the workpiece spindle controlled by the control device is varied in a sine wave. FIG. 2 is a diagram showing waviness and tooth trace error occurring in the tooth trace of gear teeth. It is a graph showing the fluctuation state of the rotational phase of the workpiece spindle and the rotational phase of the tool spindle, which are controlled by the control device. 8A is a graph showing a variation in the rotational phase synchronization error between the workpiece spindle and the tool spindle obtained from FIG. 8A. It is a diagram showing the machining state of the workpiece and the gear cutting tool when the workpiece and the gear cutting tool are viewed in the central axis direction (Z-axis direction) of the workpiece. It is a figure which shows the example of a display of the display device with which a gear processing apparatus is equipped. FIG. 6 is a diagram for explaining stability determination of the workpiece spindle rotation speed when rotating the workpiece spindle. FIG. 3 is a Bode diagram showing gain characteristics (relationship between gain and angular frequency) representing characteristics of the frequency response of the rotational speed of the workpiece spindle and the rotational speed of the tool spindle. FIG. 3 is a Bode diagram showing phase characteristics (relationship between phase and angular frequency) representing characteristics of the frequency response of the rotational speed of the workpiece spindle and the rotational speed of the tool spindle. It is a first graph which shows the fluctuation|variation of the rotational speed of a gear cutting tool and a workpiece in a modification. It is a second graph which shows the fluctuation|variation of the rotational speed of a gear cutting tool and a workpiece in a modification. It is a third graph which shows the fluctuation|variation of the rotational speed of a gear cutting tool and a workpiece in a modification. It is a figure which shows the operation|movement of the gear cutting tool and workpiece at the time of hobbing in a second embodiment.

<1. First embodiment>
(1-1. Schematic configuration of gear processing device)
A schematic configuration of a gear processing device according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the gear processing device 1 is a machining center that has three linear axes (X-axis, Y-axis, and Z-axis) and two rotation axes (A-axis and C-axis) that are orthogonal to each other as drive axes. be. The gear processing apparatus 1 mainly includes a bed 10, a column 20, a saddle 30, a tool spindle 40, a table 50, a tilt table 60, a workpiece spindle 70, and a control device 100.

Bed 10 is placed on the floor. A column 20 is provided on the top surface of this bed 10. The column 20 is provided movably in the X-axis direction (horizontal direction) by an X-axis motor 21 housed in the bed 10 and a ball screw 22 connected to the X-axis motor 21. Further, a saddle 30 is provided on the side surface of the column 20.

The saddle 30 is provided movably in the Y-axis direction (vertical direction) by a Y-axis motor 11 (see FIG. 3) housed in the column 20 and a ball screw (not shown) connected to the Y-axis motor 11. The tool spindle 40 is rotatably provided around the Z-axis by a tool spindle motor 41 (see FIG. 3) having an encoder (not shown) housed in the saddle 30. A gear cutting tool 42 (skiving cutter) is attached to the tip of the tool spindle 40, and the gear cutting tool 42 rotates as the tool spindle 40 rotates.

Here, the gear cutting tool 42 will be explained with reference to FIG. As shown in FIG. 2, the gear cutting tool 42 is a skiving cutter having a plurality of cutting edges 42a on its outer peripheral surface, and the end surface of each cutting edge 42a constitutes a rake face having a rake angle γ. The rake surface of each cutting edge 42a may be tapered around the central axis of the gear cutting tool 42, or may be formed into a plane facing in a different direction for each cutting edge 42a.

As shown in FIG. 1, a table 50 is provided on the top surface of the bed 10. The table 50 is provided movably in the Z-axis direction (horizontal direction) by a Z-axis motor 12 (see FIG. 3) housed in the bed 10 and a ball screw (not shown) connected to the Z-axis motor 12. A tilt table support section 61 that supports the tilt table 60 is provided on the upper surface of the table 50. A tilt table 60 is provided on the tilt table support portion 61 so as to be swingable around the A axis (parallel to the X axis).

A workpiece spindle motor 71 having a workpiece spindle 70 and an encoder (not shown) is provided on the bottom surface of the tilt table 60. The workpiece spindle 70 is rotatably provided around a C-axis perpendicular to the A-axis by a workpiece spindle motor 71. A workpiece W is held at the tip of the workpiece spindle 70, and the workpiece W rotates as the workpiece spindle 70 rotates.

(1-2. Configuration of control device)
The control device 100 processes a gear on the workpiece W by skiving. Specifically, as shown in FIG. 5, the control device 100 aligns the rotation axis C of the workpiece W with respect to the rotation axis O of the gear cutting tool 42 by swinging the tilt table 60 around the A axis. and tilt it. The angle of inclination of the rotational axis O of the gear cutting tool 42 with respect to the rotational axis C of the workpiece W is referred to as the intersection angle δ.

The control device 100 controls the rotational speed Sw of the workpiece spindle 70 (workpiece W), the rotational speed St of the tool spindle 40 (gear cutting tool 42), and the rotation of the workpiece W with respect to the workpiece W of the gear cutting tool 42. The feed speed Vtw in the direction of the axis (center axis C) is controlled. The rotation speed (workpiece spindle rotation speed) Sw of the workpiece spindle 70 is determined by the following equation (2), which is obtained by first-order differentiation of the command value of the rotation phase (rotation angle) θw of the workpiece spindle 70 expressed by the following equation (1). ) is controlled by the command value of the rotational speed Sw of the workpiece spindle 70. The rotation speed St of the tool spindle 40 is synchronized with the rotation speed Sw of the workpiece spindle 70. In equations (1) and (2), X is the fixed value of the workpiece spindle rotation speed Sw, A is the amplitude of the rotation phase Pw of the workpiece spindle 70, and ω is the rotation speed Sw of the workpiece spindle 70. The fluctuation frequency, t, is time.

The cutting speed St-w is set based on the machining time (cycle time) required for gear machining, the specifications of the gear cutting tool 42, the material of the workpiece W, the helix angle of the gear formed on the workpiece W, etc. be done. That is, the cutting speed St-w is set to the optimum speed, taking into account the machining efficiency during gear machining, the tool life of the gear cutting tool 42, and the like. In skiving processing, as the cutting speed St-w increases, processing efficiency improves, but quality such as surface texture tends to deteriorate.

In this example, the control device 100 varies the rotational speed Sw of the workpiece spindle 70, for example, with a sine wave shown in FIG. 6A. Accordingly, the rotational speed St of the tool spindle 40 is varied and synchronized with the rotational speed Sw of the workpiece spindle 70. Then, gear machining is performed by feeding the gear cutting tool 42 in the direction of the rotational axis C of the workpiece W at a feed rate Vtw. According to this control, the period in which the gear cutting tool 42 contacts the workpiece W becomes irregular, so that the rotational speed of the workpiece spindle 70 and the tool spindle 40 is constant without fluctuation, so that the Amplification of chatter vibrations occurring in the object W is suppressed.

However, the mass of the first rotating body including the workpiece W (the rotating part of the workpiece W and the workpiece spindle 70) and the second rotating body including the gear cutting tool 42 (the rotating part of the gear cutting tool 42 and the tool spindle 40) The mass of is not the same as Therefore, when the rotational speed Sw of the workpiece spindle 70 and the rotational speed St of the tool spindle 40 change, the first moment of inertia of the first rotating body and the second moment of inertia of the second rotating body differ. Due to the difference between the first and second moments of inertia of the first and second rotating bodies, a rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 occurs, as shown in FIG. 6B. As a result, as shown in FIG. 7, an undulation of the tooth trace error Fβe occurs in the tooth trace Gz of the tooth G of the gear to be machined, and there is a possibility that the gear machining accuracy may deteriorate. Therefore, the control device 100 reduces the rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40, and suppresses the waviness of the tooth trace Gz of the tooth G of the gear to be machined.

Next, a specific configuration of the control device 100 will be explained. As shown in FIG. 3, the control device 100 includes a workpiece spindle rotation speed control section 110, a tool spindle rotation speed control section 120, and a feed speed control section 130. Furthermore, the control device 100 includes a phase error calculation section 140, a tooth trace error calculation section 150, a tooth trace error display section 160, a correction instruction reception section 170, a phase correction command value calculation section 180, and a display device 190. Be prepared.

The workpiece spindle rotational speed control section 110 drives and controls the workpiece spindle motor 71 to vary the rotational speed Sw of the workpiece spindle 70. The tool spindle rotation speed control unit 120 drives and controls the tool spindle motor 41 to vary the rotation speed St of the tool spindle 40 and synchronize the rotation speed St of the tool spindle 40 with the rotation speed Sw of the workpiece spindle 70. . The feed rate control unit 130 drives and controls the Y-axis motor 11 and the Z-axis motor 12, feeds the gear cutting tool 42 in the direction of the rotational axis C of the workpiece W at a feed rate Vtw, and transfers the gear cutting tool 42 and the workpiece. Adjust the relative distance to W.

The phase error calculation unit 140 calculates a rotational phase synchronization error between the workpiece spindle 70 and the tool spindle 40 due to the difference in moment of inertia between the first rotating body including the workpiece W and the second rotating body including the gear cutting tool 42. If this occurs, the workpiece spindle rotation phase of the workpiece spindle 70 is input from the encoder of the workpiece spindle motor 71, and at the same time, the tool spindle rotation phase of the tool spindle 40 is input from the encoder of the tool spindle motor 41. Then, the rotation phase synchronization error between the workpiece spindle 70 and the tool spindle 40 is calculated based on the input workpiece spindle rotation phase and tool spindle rotation phase. Thereby, the rotational phase synchronization error between the workpiece spindle 70 and the tool spindle 40 can be easily grasped.

Specifically, the phase error calculation unit 140 calculates the workpiece spindle rotation phase θw (the solid line in FIG. 8A, The amplitude A) is input from the encoder of the workpiece spindle motor 71. At the same time, the tool spindle rotation phase θt (broken line in FIG. 8A) when the tool spindle 40, which is rotating at the rotation speed St in synchronization with the rotation speed Sw of the workpiece spindle 70, is idle, is determined by the tool spindle motor 41. input from the encoder. Then, the difference between the input workpiece spindle rotational phase θw and the tool spindle rotational phase θt is calculated as the rotational phase synchronization error Δθ (solid line in FIG. 8B, amplitude B) between the workpiece spindle 70 and the tool spindle 40.

In other words, as shown in FIG. 9, when the workpiece W and the gear cutting tool 42 are viewed in the direction of the central axis C (Z-axis direction) of the workpiece W, the point where the workpiece W and the gear cutting tool 42 are in contact is Let Pa be the tool spindle rotation phase θt. In this case, a point Pb shifted from the tool spindle rotational phase θt in the circumferential direction of the workpiece W by the rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 becomes the workpiece spindle rotational phase θw. Then, the arc between the points Pa and Pb becomes the amplitude B. Therefore, the rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 expressed by the following equation (3) is calculated. Note that Zt in Equation (3) is the number of tool teeth of the gear cutting tool 42, and Zw is the number of teeth of the gear to be machined on the workpiece W, which are stored in advance in the phase error calculation unit 140.

The tooth trace error calculating section 150 calculates the tooth trace error of the tooth trace of the tooth to be machined on the workpiece W, based on the rotational phase synchronization error Δθ calculated by the phase error calculating section 140. Specifically, the tooth trace error calculation unit 150 calculates the diameter d of the workpiece W, for example, the reference circle diameter, which is used to estimate and evaluate the tooth trace error expressed by the following equation (4). Note that m in Equation (4) is the module size (shift coefficient) of the gear, and is stored in advance in the tooth trace error calculation unit 150. However, instead of using the reference circle diameter as the diameter d of the workpiece W for estimating the tooth trace error, the tooth tip diameter, tooth bottom diameter, or meshing pitch diameter may be used. Then, the tooth trace error calculation unit 150 calculates a tooth trace error Fβe expressed by the following formula (5) based on the rotational phase synchronization error Δθ obtained by formulas (3) and (4) and the diameter d of the workpiece W. seek.

The tooth trace error display unit 160 displays the tooth trace error calculated by the tooth trace error calculation unit 150 on the display device 190. This allows the user to easily determine whether to process the gear or correct the error. As shown in FIG. 10, this display device 190 is, for example, a liquid crystal panel, and displays a numerical value 191 of the tooth trace error determined by the tooth trace error display section 160, an error correction instruction button 192, and a processing instruction button 193. The error correction instruction button 192 is a button that the user presses to issue an error correction instruction when the user sees the tooth trace error value 191 and determines that error correction is necessary. The machining instruction button 193 is a button that the user presses to issue a machining instruction when the user looks at the numerical value 191 of the tooth trace error and determines that error correction is not necessary.

The correction instruction receiving unit 170 detects that the error correction instruction button 192 of the display device 190 has been pressed, receives the error correction instruction, and inputs the error correction instruction to the phase correction command value calculation unit 180. Further, when the correction instruction receiving unit 170 detects that the processing instruction button 193 of the display device 190 has been pressed, it inputs the processing instruction to the workpiece spindle rotation speed control unit 110.

When the error correction command is input from the correction instruction receiving unit 170, the phase correction command value calculation unit 180 calculates the rotational phase correction command value of the workpiece spindle 70 based on the rotational phase synchronization error calculated by the phase error calculation unit 140. do. Specifically, the phase correction command value calculation unit 180 corrects the rotational phase θw of the workpiece spindle 70 corrected by the rotational phase synchronization error Δθ calculated by the phase error calculation unit 140, as shown in the following equation (6). Calculate the command value.

The workpiece spindle rotation speed control unit 110 performs first-order differentiation on the correction command value of the rotational phase θw of the workpiece spindle 70 obtained by the phase correction command value calculation unit 180, and calculates the workpiece speed as shown in the following equation (7). A correction command value for the rotational speed Sw of the workpiece spindle 70 is obtained to control the rotation of the workpiece spindle 70.

According to the gear processing apparatus 1 described above, the rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 is reduced before starting gear processing, and the waviness of the tooth thread Gz of the tooth G of the gear to be machined is suppressed. Therefore, it is possible to improve the machining accuracy of gears processed in gear machining. Since the workpiece spindle rotational speed St is varied, amplification of chatter vibration occurring in the workpiece W is suppressed. As a result, the depth of cut of the gear cutting tool 42 into the workpiece W can be set large. Therefore, it is possible to both improve the surface quality of the processed surface formed on the workpiece W and improve the processing efficiency.

(1-3. Gear processing by control device)
Next, gear machining processing (gear machining method) executed by the control device 100 will be described with reference to the drawings. Note that when performing the gear machining process, it is assumed that the workpiece W is held on the workpiece spindle 70 and the gear cutting tool 42 is attached to the tool spindle 40. Further, it is assumed that the inclination angle of the rotational axis O of the gear cutting tool 42 with respect to the rotational axis C of the workpiece W is set to an intersection angle δ, and the gear cutting tool 42 is positioned at the machining start position of the workpiece W. do.

The workpiece spindle rotational speed control unit 110 causes the workpiece spindle 70 to idle by varying the rotational speed Sw of the workpiece spindle 70 in a sine wave based on the command value of the rotational speed Sw of the workpiece spindle 70 (step S1 in FIG. 4A). , rotational speed variation process). Then, it is determined whether the rotational speed Sw of the workpiece spindle 70 is stable (step S2 in FIG. 4A, rotational speed variation step). As shown in Fig. 11, this process is stable when the average workpiece spindle rotational speed Swa of the workpiece spindle rotational speed Sw, which fluctuates in a sine wave, is within ±20% of the target center speed. Discern.

Once the workpiece spindle rotational speed Sw is stabilized, the phase error calculation unit 140 inputs the workpiece spindle rotational phase θw of the workpiece spindle 70 while the workpiece spindle 70 is idling, and at the same time inputs the tool spindle rotational phase θt of the tool spindle 40. (Step S3 in FIG. 4A, rotational phase input step). Then, based on the workpiece spindle rotation phase θw and the tool spindle rotation phase θt, a rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 is calculated (step S4 in FIG. 4A, synchronization error calculation step).

The tooth trace error calculation unit 150 calculates the tooth trace error Fβe of the tooth trace of the tooth to be machined on the workpiece W based on the rotational phase synchronization error Δθ calculated by the phase error calculation unit 140 (step S5 in FIG. 4A, tooth trace error calculation process). Then, the tooth trace error display unit 160 displays the tooth trace error Fβe calculated by the tooth trace error calculation unit 150 on the display device 190 (step S6 in FIG. 4A, tooth trace error display step). Here, the user determines whether the numerical value 191 of the tooth trace error Fβe is within the allowable range by looking at the display device 190, and if the numerical value 191 of the tooth trace error Fβe is outside the permissible range, the display device 190, press the error correction instruction button 192.

The correction instruction receiving unit 170 determines whether or not an error correction instruction has been received from the display device 190 (step S7 in FIG. 4A, correction instruction receiving step), and in this case, the error correction instruction button 192 is pressed and the error correction instruction is received. is received, the error correction command is input to the phase correction command value calculation unit 180. When the error correction command is input from the correction instruction receiving unit 170, the phase correction command value calculation unit 180 generates a correction command for the rotational phase θw of the workpiece spindle 70 based on the rotational phase synchronization error Δθ calculated by the phase error calculation unit 140. A value is calculated (step S8 in FIG. 4A, phase correction command value calculation step).

The workpiece spindle rotational speed control unit 110 calculates a correction command value for the rotational speed Sw of the workpiece spindle 70 based on the correction command value for the rotational phase θw of the workpiece spindle 70 obtained by the phase correction command value calculation unit 180. The rotational speed Sw of the workpiece spindle 70 is varied in a sinusoidal manner to cause the workpiece spindle 70 to idle (step S9 in FIG. 4A). Then, the process returns to step S2, and it is determined whether the rotational speed Sw of the workpiece spindle 70 is stable (step S2 in FIG. 4A).

Once the workpiece spindle rotational speed Sw is stabilized, the phase error calculation unit 140 inputs the workpiece spindle rotational phase θw of the workpiece spindle 70 while the workpiece spindle 70 is idling, and at the same time inputs the tool spindle rotational phase θt of the tool spindle 40. (Step S3 in FIG. 4A). Then, based on the workpiece spindle rotational phase θw and the tool spindle rotational phase θt, the rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 is calculated again (step S4 in FIG. 4A).

The tooth trace error calculation unit 150 recalculates the tooth trace error Fβe of the tooth trace to be machined on the workpiece W based on the rotational phase synchronization error Δθ calculated by the phase error calculation unit 140 (step S5 in FIG. 4A). ). Then, the tooth trace error display unit 160 displays the tooth trace error Fβe calculated by the tooth trace error calculation unit 150 again on the display device 190 (step S6 in FIG. 4A). Here, the user looks at the display device 190 and determines whether the numerical value 191 of the tooth trace error Fβe is within the permissible range, and when the numerical value 191 of the tooth trace error Fβe is within the permissible range, the display device 190, press the processing instruction button 193.

The correction instruction receiving unit 170 determines whether or not the error correction instruction has been received from the display device 190 (step S7 in FIG. 4A). 110 and proceed to step S10. The workpiece spindle rotational speed control unit 110 sets the rotational speed Sw of the workpiece spindle 70 based on the correction command value of the rotational phase θw of the workpiece spindle 70 (step S10 in FIG. 4B). Further, the tool spindle rotation speed control unit 120 sets the rotation speed St of the tool spindle 40 so as to be synchronized with the rotation speed Sw of the workpiece spindle 70 set by the workpiece spindle rotation speed control unit 110 (FIG. 4B step S11). Then, the feed speed control unit 130 sets the feed speed Vtw (step S12 in FIG. 4B).

Through the above processing, the gear cutting tool 42 performs continuous gear machining on the workpiece W while meshing with the workpiece W, and processes the tooth flank shape on the workpiece W (step S13 in FIG. 4B). Then, it is determined whether the gear machining of the first workpiece W is completed (step S14 in FIG. 4B), and when the gear machining of the first workpiece W is completed, it is determined whether or not the gear machining of the next workpiece W is to be performed. Confirm (step S15 in FIG. 4B). Then, when there is gear machining for the next workpiece W, the process returns to step S13 and the above-mentioned process is repeated, and when there is no gear machining for the next workpiece W, all the processes are ended.

According to this gear machining process, the tooth trace error can be reduced until the user is satisfied with the process before starting gear machining, so it is possible to improve the machining accuracy of the gear to be machined during gear machining. In particular, in the case of large gears, conventionally the machined gears are actually machined and the machined gears are actually measured to check for tooth trace errors under one condition, which poses a problem of high material and work costs. According to this gear machining process, the tooth trace error can be calculated only by idle rotation of the workpiece spindle 70 and the tool spindle 40, and a significant cost reduction can be achieved.

(1-4. Modification of the first embodiment)
In the example of the first embodiment, the rotational phase synchronization error Δθ between the workpiece spindle 70 and the tool spindle 40 is calculated based on the workpiece spindle rotational phase θw and the tool spindle rotational phase θt. However, the phase error calculation unit 140 calculates the rotation speed Sw of the workpiece spindle 70 based on the workpiece spindle rotation phase θw, and calculates the rotation speed St of the tool spindle 40 based on the tool spindle rotation phase θt. do. Further, a configuration may be adopted in which the frequency response error between the rotational speed Sw of the workpiece spindle 70 and the rotational speed St of the tool spindle 40 is calculated.

Specifically, as shown in FIGS. 12A and 12B, the Bode diagram, which graphically expresses the characteristics of the frequency response, has the following characteristics: gain characteristics (relationship between gain and angular frequency) and phase characteristics (relationship between phase and angular frequency). There are two types. Therefore, the phase error calculation unit 140 calculates the gain characteristics (solid line in FIG. 12A) and phase characteristics (solid line in FIG. 12B) of the rotational speed Sw of the workpiece spindle 70 and the gain characteristics (solid line in FIG. 12A) of the rotational speed St of the tool spindle 40. The frequency response error is calculated based on the phase characteristics (dashed line in FIG. 12B) and the phase characteristics (dashed line in FIG. 12B). Then, the phase correction command value calculation unit 180 calculates the rotational speed correction amount of the workpiece spindle 70 based on the calculated frequency response error.

Further, in the example of the first embodiment, a case has been described in which the rotation speed Sw of the workpiece spindle 70 is varied in a sine wave, but as shown in FIG. 13A, the rotation speed Sw of the workpiece spindle 70 is varied in a triangular wave. It may be changed by Similarly, the rotational speed Sw of the workpiece spindle 70 may be varied so that the parabola changes in a wavy manner. Further, the rotational speed Sw of the workpiece spindle 70 may be linearly accelerated or decelerated. For example, the workpiece spindle rotational speed control unit 110 may accelerate the rotational speed Sw of the workpiece spindle 70 at a constant acceleration, as shown in FIG. 13B. Similarly, the workpiece spindle rotational speed control unit 110 may reduce the rotational speed Sw of the workpiece spindle 70 at a constant deceleration rate, as shown in FIG. 13C.

Further, in the example of the first embodiment, the user looks at the numerical value 191 of the tooth trace error, determines whether or not error correction is necessary, and issues an error correction instruction or machining instruction. However, for example, the tooth trace error calculation unit 150 determines whether the calculated tooth trace error Fβe of the tooth trace Gz is within a predetermined target tooth trace error range, and if it is outside the range of the target tooth trace error, phase correction is performed. The instruction may be automatically issued, and if the error is within the target tooth trace error, the machining instruction may be automatically issued.

<2. Second embodiment>
Next, a second embodiment will be described with reference to FIG. 14. In the first embodiment (a modification of the first embodiment), a case has been described in which the gear cutting tool 42 is a skiving cutter and the gear processing apparatus 1 performs gear processing by skiving. On the other hand, in the second embodiment, a case will be described in which the gear cutting tool 242 is a hob cutter and the gear processing apparatus 1 performs gear processing by hobbing. Note that the same parts as in the first embodiment described above are given the same reference numerals, and their explanations will be omitted.

The gear processing device 1 arranges the gear cutting tool 242 and the workpiece W so that the rotation axis O of the gear cutting tool 242 and the C axis, which is the rotational axis of the workpiece W, intersect. In addition, in FIG. 14, the gear cutting tool 242 and the workpiece W are arranged so that the rotational axis O of the gearing tool 242 and the C axis, which is the rotational axis of the workpiece W, are orthogonal to each other. During gear machining, the gear processing device 1 sends (relatively moves) the gear cutting tool 242 in the Z-axis direction, which is the central axis of the workpiece W, while rotating the workpiece W and the gear cutting tool 242 respectively. By doing so, a gear is machined onto the workpiece W.

In this gear machining, the rotational phase synchronization error between the workpiece spindle 70 and the tool spindle 40 can be reduced, and the waviness of the tooth trace of the teeth of the gear to be machined can be suppressed, thereby increasing the machining accuracy of the gear to be machined in gear machining. be able to. Since the rotational speed of the workpiece main shaft 70 is varied, amplification of chatter vibrations occurring in the workpiece W is suppressed. As a result, the depth of cut of the gear cutting tool 242 into the workpiece W can be set large. Therefore, it is possible to both improve the surface quality of the processed surface formed on the workpiece W and improve the processing efficiency.

<3. Others＞
In each of the above embodiments, the configuration is such that the tooth trace error of the gear tooth trace is estimated before gear machining, but the configuration may be such that the tooth trace error of the gear tooth trace is estimated during rough machining. Thereby, cycle time can be shortened. Furthermore, since it is possible to suppress waviness of the gear tooth trace during finishing machining, the machining accuracy of the gear can be improved. Furthermore, since the amplification of regenerative chatter vibrations generated in the workpiece W that has undergone a weight change during rough machining can be suppressed, the surface quality of the machined surface formed on the workpiece W can be further improved. Note that the configuration may be such that the tooth trace error of the gear tooth trace is estimated before gear machining and during gear machining.

Further, in each of the above embodiments, the rotational phase correction amount of the workpiece spindle 70 is calculated, but the rotational phase correction amount of the tool spindle 40 may be calculated. Alternatively, a configuration may be adopted in which the rotational phase correction amounts of both the workpiece spindle 70 and the tool spindle 40 are calculated. In this case, the rotational phase correction amount of the workpiece spindle 70 and the rotational phase correction amount of the tool spindle 40 are calculated at a ratio of 50% to 50%, or the number of teeth of the gear to be machined on the workpiece W and the gear cutting tool 42 are calculated. It is determined by the ratio of the number of teeth.

Further, in each of the above embodiments, the gear processing apparatus 1 is configured such that the column 20 is movable in the X-axis direction, but the table 50 may be configured to be movable in the X-axis direction instead of the column 20. . Moreover, although the configuration in which the table 50 is movable in the Z-axis direction has been described, the column 20 may be configured to be movable in the Z-axis direction instead of the table 50. Further, although a horizontal machining center has been described as the gear processing device 1, the present invention is also applicable to a vertical machining center. Further, the present invention is applicable to machine tools in general.

1: Gear processing device, 40: Tool spindle, 41: Tool spindle motor, 42: Gear cutting tool, 70: Workpiece spindle, 71: Workpiece spindle motor, 100: Control device, 110: Workpiece spindle rotation speed Control unit, 120: Tool spindle rotation speed control unit, 130: Feed rate control unit, 140: Phase error calculation unit, 150: Tooth trace error calculation unit, 160: Tooth trace error display unit, 170: Correction instruction reception unit, 180 : Phase correction command value calculation unit, 190: Display device, W: Workpiece

Claims (9)

Gear machining in which gear teeth are machined on the workpiece by moving the gear cutting tool relative to the workpiece in the direction of the rotational axis of the workpiece while rotating the workpiece and the gear cutting tool synchronously. A device,
a workpiece spindle rotatably supporting the workpiece;
a rotatable tool spindle on which the gear cutting tool is mounted;
a workpiece spindle rotational speed control unit that varies the rotational speed of the workpiece spindle;
a tool spindle rotation speed control unit that varies the rotation speed of the tool spindle;
A rotational phase synchronization error between the workpiece spindle and the tool spindle is caused by a difference between the first moment of inertia of the first rotating body including the workpiece and the second moment of inertia of the second rotating body including the gear cutting tool. a phase error calculation unit that calculates the rotational phase synchronization error based on the workpiece spindle rotational phase of the workpiece spindle and the tool spindle rotational phase of the tool spindle when the rotational phase synchronization error occurs;
a tooth trace error calculation unit that calculates a tooth trace error of teeth of the gear to be machined on the workpiece based on the rotational phase synchronization error calculated by the phase error calculation unit;
A gear processing device equipped with. The gear processing device further includes:
a tooth trace error display unit that displays the tooth trace error calculated by the tooth trace error calculation unit on a display device;
The gear processing device according to claim 1, comprising: The gear processing device further includes:
a correction instruction receiving unit that receives an error correction instruction from a user who makes a judgment by looking at the tooth trace error displayed on the display device;
When the error correction instruction is received by the correction instruction receiving unit, a rotational phase correction command value for at least one of the workpiece spindle and the tool spindle is determined based on the rotational phase synchronization error calculated by the phase error calculation unit. a phase correction command value calculation unit to calculate;
The gear processing device according to claim 2, comprising: The gear processing device further includes:
a phase correction command value calculation unit that calculates a rotational phase correction command value for at least one of the workpiece spindle and the tool spindle based on the rotational phase synchronization error calculated by the phase error calculation unit,
The tooth trace error calculation unit calculates the tooth trace error after correction based on the rotational phase synchronization error calculated by the phase error calculation unit,
The gear processing apparatus according to claim 2, wherein the tooth trace error display section displays the corrected tooth trace error calculated by the tooth trace error calculation section on the display device. The gear processing device further includes:
2. The method according to claim 1, further comprising a phase correction command value calculation unit that calculates a rotational phase correction command value for at least one of the workpiece spindle and the tool spindle based on the rotational phase synchronization error calculated by the phase error calculation unit. The gear processing device described. The gear cutting tool is a skiving cutter,
The gear processing device moves the gear cutting tool relative to the workpiece in the direction of the rotational axis of the workpiece, with the rotational axis of the workpiece being inclined with respect to the rotational axis of the gear cutting tool. The gear processing apparatus according to any one of claims 1 to 5, wherein the gear skiving process is performed on the workpiece by skiving the gear. While synchronously rotating a workpiece spindle that rotatably supports the workpiece and a rotatable tool spindle on which the gear cutting tool is attached, the gear cutting tool is moved relative to the workpiece in the direction of the rotational axis of the workpiece. A gear machining method for machining gear teeth on the workpiece by relative movement, the method comprising:
a rotational speed varying step of varying the rotational speed of the workpiece spindle and the tool spindle;
A rotation phase input step of inputting a tool spindle rotation phase of the tool spindle at the same time as inputting a work spindle rotation phase of the workpiece spindle while the rotation speed is changing;
A rotational phase synchronization error between the workpiece spindle and the tool spindle is caused by a difference between the first moment of inertia of the first rotating body including the workpiece and the second moment of inertia of the second rotating body including the gear cutting tool. a phase error calculation step of calculating the rotational phase synchronization error based on the workpiece spindle rotational phase of the workpiece spindle and the tool spindle rotational phase of the tool spindle when the rotational phase synchronization error occurs;
a tooth trace error calculation step of calculating a tooth trace error of the teeth of the gear to be machined on the workpiece based on the rotational phase synchronization error calculated in the phase error calculation step;
A gear processing method comprising: The gear processing method further includes:
a tooth trace error display step of displaying the tooth trace error calculated in the tooth trace error calculation step on a display device;
The gear processing method according to claim 7, comprising: The gear processing method further includes:
a correction instruction receiving step of receiving an error correction instruction from a user who makes a judgment by looking at the tooth trace error displayed on the display device;
When the error correction instruction is received in the correction instruction receiving step, a rotational phase correction command value of at least one of the workpiece spindle and the tool spindle is determined based on the rotational phase synchronization error calculated in the phase error calculation step. a step of calculating a phase correction command value;
The gear processing method according to claim 8, comprising:

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