Gear grinding process simulation method

Abstract

This gear grinding process simulation method for simulating a tooth surface shape formed on a workpiece by a gear grinding process for forming a gear on the workpiece by using a grindstone comprises: an ideal dresser shape calculation step (S3) for calculating, on the basis of input information including a design shape of the grindstone, the ideal shape of a dresser for dressing the grindstone; an approximate dresser shape calculation step (S4) for calculating, on the basis of the ideal shape of the dresser, an approximate shape of the dresser including a tooth surface approximated by a shape that includes an arc satisfying a prescribed curvature condition; and a post-dressing grindstone shape calculation step (S5) for calculating the post-dressing shape of the grindstone after the dressing by the dresser having the approximate shape.

Description

Gear grinding simulation method

[0001] The present invention relates to a gear grinding simulation method.

[0002] In gear grinding, a dresser is used to form a threaded grinding wheel, and the threaded grinding wheel is used to grind a gear. As a simulation method for predicting the shape of a gear after grinding, Patent Documents 1 to 3 disclose calculating an ideal dresser shape for an ideal workpiece tooth profile that matches a target gear shape, calculating an ideal grinding wheel shape from the ideal dresser shape, and further calculating the gear shape based on the calculated grinding wheel shape. Then, the grinding wheel shape and the gear shape are calculated in consideration of setting conditions, and various correction amounts are determined.

[0003] Japanese Patent Application Laid-Open No. 2016-083744, Japanese Patent Application Laid-Open No. 2016-083745, Japanese Patent Application Laid-Open No. 2016-083746

[0004] However, with the configurations disclosed in Patent Documents 1 to 3, in order to simulate gear processing with high accuracy, it is necessary to repeat actual processing to determine the correction amount, which causes rework and reduces workability.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a gear grinding simulation method that has good workability and enables high-precision simulation of gear processing.

[0006] One aspect of the present disclosure is a gear grinding simulation method for simulating a tooth flank shape formed on a workpiece by gear grinding in which a gear is formed on the workpiece using a grinding wheel, the method comprising: a dresser ideal shape calculating step of calculating an ideal shape of a dresser for dressing the grinding wheel based on input information including a design shape of the grinding wheel; a dresser approximate shape calculating step of calculating an approximate shape of the dresser having a tooth flank approximated by a shape including an arc that satisfies a predetermined curvature condition based on the ideal shape of the dresser; and a post-dressing grinding wheel shape calculating step of calculating a post-dressing shape that is the shape of the grinding wheel after being dressed by the dresser having the approximate shape.

[0007] According to the gear grinding simulation method of this embodiment, the grinding wheel shape dressed by a dresser having an approximate shape that approximates the ideal shape of the dresser so that the tooth surface of the dresser satisfies a predetermined curvature condition is calculated. Therefore, the dresser can be made into a shape that is easy to form, and the actual manufacturing error of the dresser can be reduced. In addition, the dresser shape can be measured, and the approximate dresser shape can be calculated from the measurement results, and the dressed grinding wheel shape can be calculated. As a result, it is not necessary to repeatedly perform actual processing in order to simulate tooth surface processing with high precision as in the conventional method, and rework is not required, thus improving work efficiency.

[0008] As described above, according to one embodiment, a gear grinding simulation method can be provided that offers good workability and enables high-precision simulation of gear machining.

[0009] This is a diagram of a gear grinding machine in Embodiment 1. This is a diagram of a gear grinding machine in Embodiment 1, viewed from the left side of Figure 1. This is a functional block diagram of a gear grinding simulation device. This is a conceptual cross-sectional diagram of the ideal shape of a gear in Embodiment 1. This is a conceptual cross-sectional diagram of the ideal shape of a grinding wheel in Embodiment 1. This is a conceptual cross-sectional diagram of the ideal shape of a dresser in Embodiment 1. This is a conceptual cross-sectional diagram of the approximate shape of a dresser in Embodiment 1. This is a conceptual cross-sectional diagram of the shape of a grinding wheel after dressing in Embodiment 1. This is a conceptual cross-sectional diagram of the evaluated shape of a gear in Embodiment 1. This is a diagram showing the first comparison result of gear shapes in Embodiment 1. This is a diagram showing the second comparison result of gear shapes in Embodiment 1. This is a flowchart of a gear grinding simulation method in Embodiment 1.

[0010] (Embodiment 1) 1. Overview of the Gear Grinding Simulation Method The gear grinding simulation method of this embodiment 1 simulates the tooth surface shape formed on a workpiece by gear grinding, which is the process of forming a gear on a workpiece using a grinding wheel. In the gear grinding simulation method, the machine used to perform the gear grinding is not limited, but in this embodiment, the gear grinding machine 1 shown in Figures 1 and 2 is used. The gear to be processed is an external gear, and may be a spur gear or a helical gear. The gear grinding simulation method of this embodiment 1 is executed by the gear grinding simulation device 20 shown in Figure 3. The configuration of the gear grinding machine 1 and the gear grinding simulation device 20 and the gear grinding simulation method will be described in detail below.

[0011] 2. As shown in the configuration diagram 1 of the gear grinding machine 1, the gear grinding machine 1 grinds the workpiece W using a screw-shaped grinding wheel T to create a gear tooth profile on the workpiece W. Specifically, the gear grinding machine 1 rotates the screw-shaped grinding wheel T around its central axis, and while the workpiece W is rotated around its central axis, it grinds the gear tooth profile on the workpiece W by moving the screw-shaped grinding wheel T relative to the workpiece W in the direction of the central axis.

[0012] The gear grinding machine 1 is configured to allow relative movement of the workpiece W and the screw-shaped grinding wheel T in each of the three orthogonal axes. Furthermore, the gear grinding machine 1 is configured to allow rotation of the workpiece W around the central axis of the workpiece W, and to allow rotation of the screw-shaped grinding wheel T around the central axis of the screw-shaped grinding wheel T, and to allow rotation of either the workpiece W or the screw-shaped grinding wheel T in order to change the relative position of the workpiece W and the screw-shaped grinding wheel T.

[0013] The gear grinding machine 1 is a 6-axis machine, that is, a machine having 3 linear axes and 3 rotational axes. In this embodiment, the gear grinding machine 1 makes the workpiece W rotatable around the B axis, the screw-shaped grinding wheel T rotatable around the A axis and the C axis, and the screw-shaped grinding wheel T movable in the X, Y, and Z directions. The A axis is an axis perpendicular to the central axis of the workpiece W and the central axis of the screw-shaped grinding wheel T. The B axis coincides with the central axis of the workpiece W. The C axis coincides with the central axis of the screw-shaped grinding wheel T.

[0014] The gear grinding machine 1 comprises a bed 2, a column 3, a Y-axis slide 4, a rotating member 5, a grinding wheel support member 6, a screw-shaped grinding wheel T, a workpiece support member 7, a dresser 8, and a dresser support member 9. The bed 2 is installed on a mounting surface. The column 3 is provided to be movable in the X-axis direction (horizontal direction) relative to the bed 2 by being guided by an X-axis guide 10 provided on the upper surface of the bed 2, and is also provided to be movable in the P direction (front-back direction) relative to the bed 2 by being guided by a P-direction guide 11 shown in Figure 2. Although not shown, the column 3 is driven by a ball screw mechanism or a linear motor or the like.

[0015] The Y-axis slide 4 is guided by a Y-axis guide provided on the vertically extending side surface of the column 3 and is mounted to be movable in the Y-axis direction (up and down direction) relative to the column 3. The rotating member 5 is mounted on the Y-axis slide 4 and is mounted to be rotatable about the A-axis, which is the horizontal axis. The rotating member 5 is mounted to be rotatable within a range of 360°, for example.

[0016] The grinding wheel support member 6 is guided by a Z-axis guide provided on the rotating member 5 and is mounted to be movable in the Z-axis direction. The direction of the Z-axis direction varies as the rotating member 5 rotates around the A-axis. In the initial state, the Z-axis direction is horizontal and perpendicular to the X-axis and Y-axis directions.

[0017] The grinding wheel support member 6 supports the threaded grinding wheel T so that it can rotate around the C axis. The C axis coincides with the central axis of the threaded grinding wheel T and is parallel to the Z axis. The threaded grinding wheel T has a helical protrusion that projects radially outward. The threaded grinding wheel T may be a single-start thread or a multi-start thread. In the case of a multi-start thread, the threaded grinding wheel T will have multiple helical protrusions. The workpiece support member 7 is provided on the bed 2 and supports the workpiece W so that it can rotate around the B axis.

[0018] The dresser 8 is disc-shaped, and its radial outer surface has a toothed surface with groove-shaped blades. The dresser support member 9 is provided on the bed 2 and supports the dresser 8 so that it can rotate around the Q axis. The Q axis coincides with the central axis of the dresser 8.

[0019] 2-1. Grinding by the Gear Grinding Machine 1 The grinding by the gear grinding machine 1 is performed as follows. First, as shown in Figure 2, the column 3 is guided by the P-direction guide 11 so that the screw-shaped grinding wheel T is facing the workpiece W in the X-axis direction, as shown in Figure 1. The workpiece W is rotated around the B axis, and the screw-shaped grinding wheel T is rotated around the C axis, and the rotations of both are synchronized.

[0020] Next, in order to position the workpiece W and the threaded grinding wheel T at an intersection angle for grinding, in this embodiment, the rotating member 5 is rotated by a predetermined angle around the A axis. Subsequently, the column 3 is moved in the X-axis direction, the Y-axis slide 4 is moved in the Y-axis direction, and the grinding wheel support member 6 is moved in the Z-axis direction, thereby moving the threaded grinding wheel T to the initial grinding position. Subsequently, by moving the Y-axis slide 4, the threaded grinding wheel T is moved in the direction of the central axis of the workpiece W, and the tooth profile of the workpiece W is ground.

[0021] 2-2. Dressing in the Gear Grinding Machine 1 Dressing in the gear grinding machine 1 is performed as follows. First, the column 3 is moved by the P-direction guide 11 so that the screw-shaped grinding wheel T is facing the dresser 8 in the X-axis direction, and the dresser 8 is rotated around the Q-axis, and the screw-shaped grinding wheel T is rotated around the C-axis. If necessary, the rotating member 5 can be rotated by a predetermined angle around the A-axis so that the dresser 8 and the screw-shaped grinding wheel T intersect at an angle. Next, the column 3 is moved in the X-axis direction, the Y-axis slide 4 is moved in the Y-axis direction, and the grinding wheel support member 6 is moved in the Z-axis direction to move the screw-shaped grinding wheel T to the initial grinding position. Then, by moving the screw-shaped grinding wheel T in the Y-axis and / or Z-axis direction in synchronization with the rotation of the C-axis, the screw-shaped grinding wheel T is moved in the direction of the central axis of the dresser 8, and the grinding wheel T is shaped.

[0022] 3. Configuration of the Gear Grinding Simulation Device 20 The gear grinding simulation device 20 of this embodiment 1 is composed of a computing device and a storage device capable of executing predetermined programs that perform the functions described later. As shown in Figure 3, the functional block representing the gear grinding simulation device 20 is composed of a gear ideal shape setting unit 21, a gear modification shape calculation unit 22, a grinding wheel shape calculation unit 23, a dresser ideal shape calculation unit 24, a dresser approximate shape calculation unit 25, a grinding wheel post-dressing shape calculation unit 26, a gear evaluation shape calculation unit 27, a gear shape comparison unit 28, a shape modification necessity determination unit 29, a feedback necessity determination unit 30, and a feedback setting unit 31. The following configuration will be described in detail below.

[0023] 3-1. Gear Ideal Shape Setting Unit 21 The gear ideal shape setting unit 21 sets the ideal shape of the gear to be machined. The ideal shape of the gear can be set arbitrarily by the user. In this embodiment, as shown in Figure 4, the cross-section of the ideal shape Wa of the gear is shown as a point cloud.

[0024] 3-2. Gear Correction Shape Calculation Unit 22 The gear correction shape calculation unit 22 calculates a corrected shape by modifying the ideal shape of the gear when the gear correction necessity determination unit 29, described later, determines that the gear shape needs to be corrected. Alternatively, if a corrected shape has been calculated in the previous simulation and it is determined that further correction is necessary, the unit calculates a corrected shape by modifying the previous corrected shape. The correction items and correction amounts in the gear correction shape calculation unit 22 can be set based on the comparison results of the gear shape comparison unit 28, described later. In this embodiment, the correction items can be the helix angle, pressure angle, the distance between the centers of the grinding wheel T and the workpiece W, etc.

[0025] 3-3. Grinding Wheel Shape Calculation Unit 23 The grinding wheel shape calculation unit 23 calculates a grinding wheel shape that corresponds to the ideal gear shape set by the gear ideal shape setting unit 21 or the modified gear shape calculated by the gear modified shape calculation unit 22, as the design shape of the grinding wheel T. In this embodiment, the grinding wheel T is a screw-shaped grinding wheel. Also, for example, the cross-section of the design shape Ta of the grinding wheel T is shown as a point cloud, as shown in Figure 5.

[0026] 3-4. Dresser Ideal Shape Calculation Unit 24 The dresser ideal shape calculation unit 24 calculates the ideal shape 8a of the dresser 8 for dressing the grinding wheel T based on input information including the design shape of the grinding wheel T. The input information may include, in addition to the design shape of the grinding wheel T, the specifications of the grinding wheel T and the dresser 8, the distance between the centers of the grinding wheel T and the workpiece W, and the intersection angle. For example, the cross-section of the ideal shape 8a of the dresser 8 is shown as a point cloud, as shown in Figure 6.

[0027] 3-5. Dresser Approximate Shape Calculation Unit 25 The dresser approximate shape calculation unit 25 calculates an approximate shape 8b of the dresser 8 having a tooth surface approximated by a shape including an arc that satisfies predetermined curvature conditions, based on the ideal shape 8a of the dresser 8. In this embodiment, the curvature condition of the arc is that the radius of curvature of the arc is within the range of 1 to 10,000 mm.

[0028] For example, the cross-section of the approximate shape 8b of the dresser 8 is represented by a plurality of straight lines and curves, as shown in Figure 7. The tooth surface 81 in the approximate shape 8b is assumed to consist of a curve along a single circular arc, but it is not limited to this, and may consist of curves along multiple circular arcs, or it may consist of a combination of curves along one or more circular arcs and straight lines. The radius of curvature W3 of the tooth surface 81 is in the range of 1 to 10,000 mm, satisfying the above curvature condition.

[0029] In the approximate shape 8b, in addition to the radius of curvature W3 of the tooth surface 81, the tooth height W1, the angle W2 of the tooth surface 81, the width W4 of the tooth groove 82, the distance W5 from the tooth tip 83 to the effective diameter 84 at the center-to-center distance between the dresser 8 and the grinding wheel T, the distance W6 from the effective diameter 84 to the tooth root 85, and the width W7 of the tooth tip 83 are defined. In this embodiment, the angle W2 of the tooth surface 81 is the angle between the straight line connecting the tooth tip 811 and the tooth root 812 of the tooth surface 81 in the approximate shape 8b of the dresser 8 and the radial straight line perpendicular to the axis of the dresser 8.

[0030] 3-6. Grinding Wheel Dressing Shape Calculation Unit 26 The grinding wheel dressing shape calculation unit 26 calculates the dressing shape Tb, which is the shape of the grinding wheel T after dressing with a dresser 8 having an approximate shape 8b. In this embodiment, the dressing shape Tb of the grinding wheel T is shown as a point cloud as shown in Figure 8.

[0031] 3-7. Gear Evaluation Shape Calculation Unit 27 The gear evaluation shape calculation unit 27 simulates gear grinding using a grinding wheel T having a dressed shape Tb, and calculates the evaluation shape Wb, which is the tooth surface shape formed by the gear grinding process. The evaluation shape Wb is compared with the involute tooth surface, and the point cloud shown in Figure 9 is arranged in the direction of the workpiece axis, and the amount of correction (error) in the tooth profile direction and tooth trace direction is calculated.

[0032] 3-8. Gear Shape Comparison Unit 28 The gear shape comparison unit 28 compares the evaluated gear shape Wb with the modified gear shape. In the case of the first time, or when the modified gear shape has not been calculated by the gear modified shape calculation unit 22, the evaluated gear shape Wb is compared with the ideal gear shape Wa. In this embodiment, as a comparison result, the error in the tooth surface shape between the evaluated gear shape Wb and the ideal gear shape Wa is calculated, as shown in Figure 10. Also, as a comparison result, grinding marks and waviness on the tooth surface are calculated, as shown in Figure 11. Furthermore, as a comparison result, pressure angle correction amount, helix angle correction amount, tooth profile roundness correction amount, crowning, bias correction amount, etc. can also be calculated.

[0033] 3-9. Shape Modification Necessity Determination Unit 29 The shape modification necessity determination unit 29 determines whether the ideal shape or modified shape of the gear needs to be modified based on the comparison results of the gear shape comparison unit 28. For example, it can determine that modification is necessary if the error between the evaluated shape Wb of the gear and the ideal shape Wa of the gear is greater than or equal to a predetermined value, and that modification is unnecessary otherwise.

[0034] 3-10. Feedback Necessity Determination Unit 30 Based on the comparison results of the gear shape comparison unit 28, the feedback necessity determination unit 30 determines whether feedback is necessary for one or more of the grinding wheel shape calculation unit 23, dresser approximation shape calculation unit 25, grinding wheel dressing shape calculation unit 26, and gear evaluation shape calculation unit 27, including either modification of setting conditions or implementation of additional movements. The setting conditions can be the distance between the centers of the grinding wheel T and the workpiece W and the intersection angle, the distance between the centers of the dresser 8 and the grinding wheel T and the intersection angle, etc. Additional movements can be exemplified by the feed amount (lead) of the grinding wheel T or the dresser 8.

[0035] 3-11. Feedback Setting Unit 31 The Feedback Setting Unit 31 sets the content of the feedback when the Feedback Necessity Determination Unit 30 determines that feedback is necessary. The Feedback Setting Unit 31 sets the setting conditions, including the distance between the centers of the grinding wheel T and the workpiece W, the distance between the centers of the dresser 8 and the grinding wheel T, the intersection angle, and the lead value as an additional movement.

[0036] 4. Gear Grinding Simulation Method Next, the gear grinding simulation method in this embodiment will be described in detail with reference to Figure 12. In the gear grinding simulation method, first, in the gear ideal shape setting step shown in step S1 of Figure 12, the gear ideal shape setting unit 21 sets the ideal shape Wa of the gear to be machined.

[0037] Next, in the grinding wheel shape calculation step shown in step S2 of Figure 12, the grinding wheel shape calculation unit 23 calculates the grinding wheel shape Ta, which corresponds to the ideal gear shape set in the gear ideal shape setting unit 21, as the design shape of the grinding wheel T. Then, in the dresser ideal shape calculation step shown in step S3 of Figure 12, the dresser ideal shape calculation unit 24 calculates the ideal shape 8a of the dresser 8 for dressing the grinding wheel T, based on the input information including the design shape of the grinding wheel T.

[0038] Subsequently, in the dresser approximation shape calculation step shown in step S4 of Figure 12, the dresser approximation shape calculation unit 25 calculates an approximate shape 8b of the dresser 8 having a tooth surface approximated by a shape including an arc that satisfies a predetermined curvature condition, based on the ideal shape 8a of the dresser 8. Then, in the grinding wheel dressing shape calculation step shown in step S5 of Figure 12, the grinding wheel dressing shape calculation unit 26 calculates the post-dressing shape Tb, which is the shape of the grinding wheel T after dressing with the dresser 8 having the approximate shape 8b.

[0039] Then, in the gear evaluation shape calculation step shown in step S6 of Figure 12, the gear evaluation shape calculation unit 27 calculates the evaluation shape Wb, which is the shape of the gear formed by gear grinding using a grinding wheel T having a dressed shape Tb. Subsequently, in the gear shape comparison step shown in step S7 of Figure 12, the gear shape comparison unit 28 compares the evaluation shape Wb of the gear with the ideal shape Wa of the gear.

[0040] Subsequently, in step S8 of Figure 12, as a shape modification necessity determination step, the shape modification necessity determination unit 29 determines whether or not the ideal gear shape Wa needs to be modified based on the comparison results of the gear shape comparison step S7. At the same time, in step S8 of Figure 12, as a feedback necessity determination step, the unit determines whether or not feedback is necessary for one or more of the grinding wheel shape calculation step S2, dresser approximation shape calculation step S4, grinding wheel dressing post-shape calculation step S5, and gear evaluation shape calculation step S6, including either modification of setting conditions or implementation of additional motion, based on the comparison results of the gear shape comparison step S7.

[0041] If the determination result in step S8 of Figure 12 indicates that shape modification is necessary, the gear modification shape calculation process shown in step S9 calculates a modified shape by correcting the ideal gear shape Wa. Also, if the determination result in step S8 of Figure 12 indicates that feedback is necessary, the content of the feedback is set in the feedback setting process shown in step S10.

[0042] Then, steps S2 and beyond are performed again. If a modified shape has been calculated in the gear modified shape calculation step S9, when the grinding wheel shape calculation step S2 is performed again, the grinding wheel shape corresponding to the modified shape is calculated; when the gear shape comparison step S7 is performed, the gear evaluation shape Wb and the modified shape of the gear are compared; when the shape modification necessity determination step S8 is performed again, the necessity of modifying the modified shape is determined; and when the gear modified shape calculation step S9 is performed again, the modified shape of the modified shape is calculated. In addition, if the content of the feedback has been set in the feedback setting step S10, each step is performed reflecting the content of the feedback.

[0043] For example, if there is an error in the tooth flank shape according to the comparison result of the gear shape comparison step S7, point cloud data of a gear shape (corrected gear shape) that accounts for the correction amount is calculated, an ideal shape 8a of the dresser 8 corresponding to the corrected gear shape is calculated, and an approximate shape 8b is calculated based thereon. Then, gear grinding can be simulated again using a grinding wheel dressed by the dresser 8 having the approximate shape 8b, and pressure angle error and the like can be calculated.

[0044] Further, for example, if a helix angle correction amount is calculated in the comparison result of the gear shape comparison step S7, it is determined that feedback is required when the helix angle correction amount exceeds a predetermined reference value, and tooth flank correction that achieves both the helix angle correction amount and a pressure angle error amount so as to cancel out the pressure angle correction amount generated according to the helix angle correction amount can be performed.

[0045] Further, for example, if the processing machine 1 vibrates, in the gear evaluation shape calculation step S6, the vibration and motion error are input to the motion of the processing machine 1 to calculate an evaluated tooth flank shape, and waviness of the tooth flank is calculated from the comparison result of the gear shape comparison step S7. Then, in the corrected gear shape calculation step S9, a corrected gear shape obtained by correcting the ideal gear shape Wa so as to cancel out the waviness shape is calculated, the ideal shape 8a and approximate shape 8b of the dresser 8 are calculated based on the corrected gear shape, and an evaluated gear shape is calculated to perform shape correction and feedback, thereby correcting tooth flank waviness.

[0046] On the other hand, in step S8 of FIG. 12, if the determination results of whether shape correction is required and whether feedback is required indicate that shape correction is not required and feedback is not required, the process proceeds to No in S8, and the flow ends.

[0047] 5. Function and Effect According to the gear grinding simulation method of the present embodiment, the grinding wheel shape Ta dressed by the dresser 8 having an approximate shape 8b obtained by approximating the ideal shape 8a of the dresser 8 so that the tooth surface of the dresser 8 satisfies a predetermined curvature condition is calculated. Therefore, the dresser 8 can be formed into a shape that is easy to mold, and the manufacturing error of the actual dresser 8 can be reduced. Accordingly, unlike the conventional technology, it is not necessary to repeatedly perform actual processing to simulate tooth surface processing with high precision, and rework does not occur, thereby improving workability.

[0048] Furthermore, in the present embodiment, the curvature condition for the approximate shape 8b includes that the radius of curvature of the circular arc is within the range of 1 mm to 10000 mm. This enables the shape of the dresser 8 to be formed into a shape that can be produced with high precision.

[0049] Furthermore, after manufacturing the dresser 8, the shape is measured, the tooth surface angle and radius of curvature of the dresser 8 are measured, the dresser 8 having the approximate shape 8b is calculated based on the measured values, and the shape after grinding wheel dressing is calculated, which enables calculation of the tooth surface shape taking into account the shape error of the dresser 8, and the pressure angle error can be corrected through feedback setting.

[0050] Furthermore, in the present embodiment, before the dresser ideal shape calculation step S3, the method includes: a gear ideal shape setting step S1 of setting the ideal gear shape Wa of the gear; and a grinding wheel shape calculation step S2 of calculating, as the design shape of the grinding wheel T, a grinding wheel shape corresponding to the ideal gear shape Wa or a modified shape obtained by modifying the ideal gear shape Wa. Accordingly, by calculating the grinding wheel shape corresponding to not only the ideal gear shape Wa but also a modified shape corrected to prevent waviness from occurring on the tooth surface in cases such as when there is vibration in the processing machine 1, gear grinding processing can be simulated with higher accuracy.

[0051] Furthermore, in this embodiment, the gear grinding simulation method includes a gear evaluation shape calculation step S6 which calculates an evaluation shape Wb, which is the shape of a gear formed by gear grinding using a grinding wheel T having the dressed shape Tb calculated in the grinding wheel dressed shape calculation step S5; a gear shape comparison step S7 which compares the evaluation shape Wb of the gear with the ideal shape Wa or modified shape of the gear; a shape modification necessity determination step S8 which determines whether or not modification of the ideal shape Wa or modified shape of the gear is necessary based on the comparison result of the gear shape comparison step S7; and a gear modification shape calculation step S9 which calculates a modified shape by modifying the ideal shape Wa or the previous modified shape of the gear if it is determined in the shape modification necessity determination step S8 that modification is necessary. In the grinding wheel shape calculation step S2, the grinding wheel shape corresponding to the modified shape of the gear calculated in the gear modification shape calculation step S9 is calculated as the design shape of the grinding wheel T. This makes it possible to simulate gear grinding with high accuracy.

[0052] Furthermore, in this embodiment, the gear grinding simulation method includes, after the grinding wheel dressing shape calculation step S5, a gear evaluation shape calculation step S6 which calculates an evaluation shape Wb, which is the shape of a gear formed by gear grinding using a grinding wheel T having the dressed shape Tb calculated in the grinding wheel dressing shape calculation step S5; a gear shape comparison step S7 which compares the evaluation shape Wb of the gear with the ideal shape Wa or modified shape of the gear; a feedback necessity determination step S8 which determines whether feedback is necessary, including either modifying the setting conditions or performing additional movements, for one or more of the grinding wheel shape calculation step S2, dresser approximation shape calculation step S4, grinding wheel dressing shape calculation step S5, and gear evaluation shape calculation step S6, based on the comparison result of the gear shape comparison step S7; and a feedback setting step S10 which sets the content of the feedback if it is determined in the feedback necessity determination step S8 that feedback is necessary. Then, among the grinding wheel shape calculation step S2, dresser approximation shape calculation step S4, grinding wheel post-dressing shape calculation step S5, and gear evaluation shape calculation step S6, the steps for which feedback is determined to be necessary in the feedback necessity determination step S8 are executed reflecting the content of the feedback set in the feedback setting step S10. This enables highly accurate simulation of gear grinding.

[0053] Furthermore, in this embodiment, in the gear shape comparison step S7, the gear evaluation shape Wb is compared with the gear ideal shape Wa or modified shape to calculate the helix angle adjustment amount. In the feedback necessity determination step S8, if the helix angle adjustment amount exceeds a predetermined standard value, it is determined that feedback is necessary for one or more of the grinding wheel shape calculation step S2, dresser approximation shape calculation step S4, grinding wheel dressing shape calculation step S5, and gear evaluation shape calculation step S6. In the feedback setting step S10, along with the helix angle adjustment amount, the content of the feedback is set to perform tooth surface modification that realizes a pressure angle error amount so as to cancel out the pressure angle error that occurs in accordance with the helix angle adjustment amount in the step where feedback is determined to be necessary. This makes it possible to cancel out the pressure angle error that occurs with the helix angle adjustment amount and to perform gear grinding simulation with high accuracy.

[0054] Furthermore, in this embodiment, in the gear shape comparison step S7, the evaluated gear shape Wb is compared with the ideal gear shape Wa or the modified shape, and the waviness generated on the tooth surface of the evaluated gear shape Wb is calculated as a result of the comparison. This makes it possible to adjust the gear so that no waviness is generated on the tooth surface.

[0055] As described above, according to one embodiment, a gear grinding simulation method can be provided that offers good workability and enables high-precision simulation of gear machining.

Claims

1. A gear grinding simulation method for simulating the tooth surface shape formed on a workpiece by gear grinding, a process in which gears are formed on a workpiece using a grinding wheel, comprising: a dresser ideal shape calculation step for calculating the ideal shape of a dresser for dressing the grinding wheel based on input information including the design shape of the grinding wheel; a dresser approximation shape calculation step for calculating the approximation shape of the dresser having a tooth surface approximated by a shape including an arc that satisfies predetermined curvature conditions, based on the ideal shape of the dresser; and a grinding wheel post-dressing shape calculation step for calculating the post-dressing shape, which is the shape of the grinding wheel after dressing with the dresser having the approximation shape.

2. The gear grinding simulation method according to claim 1, wherein the curvature condition includes the radius of curvature of the arc being in the range of 1 to 10,000 mm.

3. A gear grinding simulation method according to claim 1 or 2, comprising: a gear ideal shape setting step of setting the ideal shape of the gear before the dresser ideal shape calculation step; and a grinding wheel shape calculation step of calculating a grinding wheel shape corresponding to the ideal shape of the gear or a modified shape obtained by modifying the ideal shape of the gear as the design shape of the grinding wheel.

4. A gear grinding simulation method according to claim 3, comprising: a gear evaluation shape calculation step for calculating an evaluation shape which is the shape of the gear formed by gear grinding using the grinding wheel having the dressed shape calculated in the grinding wheel dressed shape calculation step; a gear shape comparison step for comparing the evaluation shape of the gear with the ideal shape or the modified shape of the gear; a shape modification necessity determination step for determining whether or not the ideal shape or the modified shape of the gear needs to be modified based on the comparison result of the gear shape comparison step; and a gear modification shape calculation step for calculating a modified shape which is the ideal shape or the previous modified shape of the gear modified if it is determined in the shape modification necessity determination step that the modification is necessary, wherein the grinding wheel shape calculation step calculates a grinding wheel shape corresponding to the modified shape of the gear calculated in the gear modification shape calculation step as the design shape of the grinding wheel.

5. A gear evaluation shape calculation step, which includes calculating an evaluation shape which is the shape of the gear formed by gear grinding using the grinding wheel having the dressed shape calculated in the grinding wheel dressed shape calculation step, after the grinding wheel dressed shape calculation step; a gear shape comparison step which compares the evaluation shape of the gear with the ideal shape or the modified shape of the gear; a feedback necessity determination step which determines whether feedback is necessary for one or more of the grinding wheel shape calculation step, the dresser approximation shape calculation step, the grinding wheel dressed shape calculation step, and the gear evaluation shape calculation step, including either modification of setting conditions or implementation of additional motion; and a feedback setting step which sets the content of the feedback if the feedback necessity determination step determines that the feedback is necessary. The gear grinding simulation method according to claim 3, wherein, of the grinding wheel shape calculation step, the dresser approximation shape calculation step, the grinding wheel post-dressing shape calculation step, and the gear evaluation shape calculation step, the step for which the feedback is determined to be necessary in the feedback necessity determination step is executed in accordance with the content of the feedback set in the feedback setting step.

6. The gear grinding simulation method according to claim 5, wherein in the gear shape comparison step, the evaluation shape of the gear is compared with the ideal shape or the modified shape of the gear to calculate the helix angle adjustment amount; the feedback necessity determination step determines that if the helix angle adjustment amount calculated in the gear shape comparison step exceeds a predetermined standard value, the feedback is necessary for one or more of the grinding wheel shape calculation step, the dresser approximation shape calculation step, the grinding wheel dressed shape calculation step, and the gear evaluation shape calculation step; and the feedback setting step sets the content of the feedback, which involves performing tooth surface modification that achieves a pressure angle error amount that cancels out the pressure angle adjustment amount that occurs in accordance with the helix angle adjustment amount in the step where the feedback is determined to be necessary, along with the helix angle adjustment amount.

7. The gear grinding simulation method according to claim 4, wherein in the gear shape comparison step, the evaluated shape of the gear is compared with the ideal shape or the modified shape of the gear, and the waviness occurring on the tooth surface of the evaluated shape of the gear is calculated as a result of the comparison.

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