Gear grinding method and gear grinding device

Abstract

To provide a gear grinding method and a gear grinding device capable of reducing waviness of a gear with high accuracy.SOLUTION: A gear grinding method comprises: a grinding resistance acquisition step of acquiring a target grinding resistance TR being a component in a predetermined axial direction that occurs when grinding a workpiece W using a threaded grindstone T using a reference machining program BP; a rigidity acquisition step of acquiring a target rigidity TS being a component in the predetermined axial direction of a gear grinding device 1; a relative displacement calculation step of calculating a target relative displacement TD between the workpiece W and the threaded grindstone T in the predetermined axial direction on the basis of the target grinding resistance TR and the target rigidity TS; a correction motion amount calculation step of calculating a correction motion amount CM relative to a reference motion of the gear grinding device 1 on the basis of the reference machining program BP so as to reduce the target relative displacement TD; and a grinding step of grinding the workpiece W using the threaded grindstone T on the basis of a correction machining program CP in which the correction motion amount CM is reflected in the reference machining program BP.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a gear grinding method and a gear grinding device. [Background technology]

[0002] Conventionally, a gear to be machined and a threaded grinding wheel are rotated synchronously to grind the gear using the threaded grinding wheel. Gear grinding using a threaded grinding wheel can sometimes cause waviness on the tooth flank. Waviness on the tooth flank affects the generation of gear noise. Therefore, it is desirable to reduce waviness on the tooth flank.

[0003] The waviness of the tooth flank includes waviness in the tooth trace direction and waviness in the tooth profile direction. Patent Document 1 describes a machining method that can reduce waviness in the tooth trace direction. Patent Document 1 discloses a technology in which a gear is machined with a threaded grinding wheel, a machining test is performed, and a motion that can offset the waviness is calculated from the measurement results in the tooth trace direction in the machining test, and an additional motion is applied to the workpiece rotation axis. This was expected to reduce the waviness of the tooth flank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 59-81017 Summary of the Invention [Problem to be solved by the invention]

[0005] In grinding processes that use a threaded grinding wheel to create gear tooth flanks, the threaded grinding wheel and the workpiece move in complex motions, making it difficult to calculate motions that can offset waviness from the measurement results of the tooth flank shape. Conventional methods have had the problem that it is not possible to obtain a highly accurate tooth flank shape unless the relationship between the waviness of the tooth flank shape and the machining motion is understood.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a gear grinding method and gear grinding apparatus that can reduce gear waviness with high precision. [Means for solving the problem]

[0007] One aspect of the present invention is A gear grinding method for generating a gear by grinding a workpiece with a threaded grinding wheel by operating a gear grinding device based on a processing program, comprising: a grinding resistance acquisition step of acquiring a target grinding resistance, which is a component in a predetermined axial direction of grinding resistance that occurs when grinding is performed using a reference machining program while rotating the threaded grinding wheel and the workpiece synchronously and feeding the threaded grinding wheel relative to the workpiece in the rotational axis direction of the workpiece, and the target grinding resistance corresponds to a relative feed position of the threaded grinding wheel; a stiffness acquisition step of acquiring a target stiffness, which is a component in the predetermined axial direction of the stiffness of the gear grinding device; a relative displacement calculation step of calculating a target relative displacement, which is a relative displacement between the workpiece and the threaded grinding wheel in the predetermined axial direction, based on the target grinding resistance and the target stiffness for each of the relative feed positions; a correction momentum calculation step of calculating a correction momentum with respect to a reference operation of the gear grinding device based on the reference machining program so as to reduce the target relative displacement for each relative feed position; and a grinding step of grinding the workpiece with the threaded grinding wheel to generate a gear based on a corrected machining program that adds the corrected momentum to the reference machining program.

[0008] Another aspect of the present invention is A gear grinding device that grinds a workpiece using a threaded grinding wheel to generate a gear by operating based on a machining program, a grinding resistance acquisition unit that acquires a target grinding resistance, which is a component in a predetermined axial direction of grinding resistance that occurs when performing a grinding process while rotating the threaded grinding wheel and the workpiece synchronously and feeding the threaded grinding wheel relative to the workpiece in the rotational axis direction of the workpiece using a reference machining program, and acquires the target grinding resistance that corresponds to a relative feed position of the threaded grinding wheel; a stiffness acquisition unit that acquires a target stiffness, which is a component in the predetermined axial direction of the stiffness of the gear grinding device; a relative displacement calculation unit that calculates a target relative displacement, which is a relative displacement between the workpiece and the threaded grinding wheel in the predetermined axial direction, based on the target grinding resistance and the target stiffness for each of the relative feed positions; a correction momentum calculation unit that calculates a correction momentum with respect to a reference operation of the gear grinding device based on the reference machining program so as to reduce the target relative displacement for each relative feed position; and a grinding control unit that grinds the workpiece with the threaded grinding wheel based on the reference machining program and the corrected momentum to generate a gear. [Effects of the Invention]

[0009] According to one and other aspects of the present invention, an object relative displacement is calculated based on the object grinding resistance and the object stiffness. A correction momentum is calculated to reduce the object relative displacement. Taking this correction momentum into account, a workpiece is ground with a threaded grinding wheel to generate a gear. This makes it possible to reduce gear waviness with high precision. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a gear grinding device according to a first embodiment. [Figure 2] 1 is a diagram showing a gear grinding device according to a first embodiment, as viewed from the left side of FIG. 1. FIG. [Figure 3] FIG. 2 is a block diagram showing a control device according to the first embodiment. [Figure 4]FIG. 1 is a diagram illustrating an outline of a horizontal axis surface grinding model. [Figure 5] FIG. 1 is a conceptual diagram illustrating an outline of a gear grinding simulation. [Figure 6] FIG. 2 is a diagram showing an axial direction based on a threaded grinding wheel and an axial direction based on a workpiece. [Figure 7] 1A and 1B are diagrams illustrating the waviness of the tooth surface, where (a) is a perspective view showing one tooth of a workpiece, (b) is a schematic cross-sectional view showing the state in which the tooth of the workpiece is ground by the blade of a threaded grinding wheel, (c) is a graph showing the change in the shape of the tooth surface of the formed gear in the tooth trace direction, and (d) is a graph showing the change in the shape of the tooth surface of the formed gear in the tooth profile direction. [Figure 8] 1 is a graph showing the change in grinding resistance relative to the grinding wheel feed position in the rotation axis direction of the workpiece, with the grinding resistance broken down into X-axis component, Y-axis component, and Z-axis component. [Figure 9] 1A and 1B are schematic diagrams showing an area of ​​a workpiece that is ground by a threaded grinding wheel in a gear grinding simulation, in which (a) shows the initial state of the grinding process, (b) shows the middle state of the grinding process, and (c) shows the final state of the grinding process. [Figure 10] 1A and 1B are diagrams for explaining the prior art, in which (a) is a diagram showing the target shape of the tooth surface in a reference machining program of the prior art, (b) is a graph showing the relationship between the grinding resistance in the grinding wheel axial direction and the grinding wheel feed position in the axial direction of the workpiece when grinding is performed based on the reference machining program, and (c) shows the long-period waviness formed on the tooth surface when the tooth surface is formed based on the reference machining program in the prior art. [Figure 11]1A and 1B are diagrams for explaining an overview of the correction processing program according to embodiment 1, in which (a) is a diagram showing an example of the target shape of the tooth surface in the correction processing program, (b) is a graph showing the relationship between the grinding resistance in the grinding wheel axis direction and the grinding wheel feed position in the axial direction of the workpiece when grinding is performed based on the correction processing program, (c) is a graph showing an example of the additional momentum of the axial rotation angle of the workpiece controlled by the correction processing program, and (d) is a diagram showing the shape of the tooth surface when the tooth surface is formed based on the correction processing program. [Figure 12] 4 is a flowchart showing the operation of the gear grinding device according to the first embodiment. [Figure 13] FIG. 10 is a block diagram showing a control device according to a second embodiment. [Figure 14] 10 is a main flow of the operation of the gear grinding device according to the second embodiment. [Figure 15] 10 is a flowchart showing a gear grinding simulation according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment 1) 1.1 Gear grinding equipment 1 A first embodiment will be described with reference to Figures 1 to 3. A gear grinding apparatus 1 according to this embodiment grinds a workpiece W using a threaded grinding wheel T to generate a gear. In detail, the gear grinding apparatus 1 performs grinding while synchronously rotating the threaded grinding wheel T and the workpiece W and feeding the threaded grinding wheel T relative to the workpiece W in the direction Cg of the rotation axis of the workpiece W.

[0012] The gear grinding apparatus 1 includes a bed 2, a Y-axis guide 3, a column 4, an X-axis guide 5, an X-axis slide 6, a rotating member 7, a Z-axis guide 8, a grinding wheel support member 9, a threaded grinding wheel T, a workpiece support member 10, and a control device 11. The control device 11 executes a gear grinding simulation using a computer 12. However, the computer 12 may be omitted.

[0013] Bed 2 is placed on an installation surface. Column 4 is guided by Y-axis guide 3 provided on the upper surface of bed 2 and is provided so as to be movable in the Y-axis direction (horizontal direction) relative to bed 2. Although not shown in detail, column 4 is driven by a ball screw mechanism, a linear motor, or the like.

[0014] The X-axis slide 6 is guided by an X-axis guide 5 provided on a side surface of the column 4 extending in the vertical direction, and is provided so as to be movable in the X-axis direction (up and down) relative to the column 4. The rotation member 7 is provided on the X-axis slide 6 and is provided so as to be rotatable around the A-axis, which is a horizontal axis. The rotation member 7 is provided so as to be rotatable within a range of 360°, for example.

[0015] The grindstone support member 9 is provided so as to be movable in the Z-axis direction, guided by a Z-axis guide 8 provided on the rotating member 7. The Z-axis direction changes as the rotating member 7 rotates around the A-axis.

[0016] The grinding wheel support member 9 supports the threaded grinding wheel T rotatably around the C axis. The C axis coincides with the rotational axis direction Ct of the threaded grinding wheel T and is an axis parallel to the Z axis. The threaded grinding wheel T has a spiral blade Ta that protrudes radially outward. The threaded grinding wheel T may have a single-start thread or a multiple-start thread. In the case of a multiple-start thread, the threaded grinding wheel T has multiple spiral blades Ta. The workpiece support member 10 is provided on the bed 2 and supports the workpiece W rotatably around the B axis.

[0017] The gear grinding apparatus 1 according to this embodiment is a six-axis machine, i.e., a machine having three linear axes and three rotational axes. However, the gear grinding apparatus 1 is not limited to a six-axis machine. In this embodiment, the gear grinding apparatus 1 is configured so that the workpiece W can rotate about the B axis, the threaded grinding wheel T can rotate about the A axis and the C axis, and the threaded grinding wheel T can move in the X axis, Y axis, and Z axis directions. The A axis is an axis perpendicular to the central axis of the workpiece W and the rotational axis direction Ct of the threaded grinding wheel T. The B axis coincides with the rotational axis direction Cg (central axis) of the workpiece W. The C axis coincides with the rotational axis direction Ct (central axis) of the threaded grinding wheel T.

[0018] The control device 11 is configured to include, for example, a CPU (Central Processing Unit) or a PLC (Programmable Logic Controller). As shown in Fig. 3, the control device 11 includes a gear grinding simulation unit 21, a grinding resistance acquisition unit 22, a stiffness acquisition unit 23, a relative displacement calculation unit 24, a corrected momentum calculation unit 25, a corrected machining program creation unit 26, a grinding control unit 27, and a storage unit 28.

[0019] The computer 12 may have a known configuration including a processor, memory, and peripheral circuits.

[0020] The configuration of the control device 11 will be described in detail below. (1) Gear grinding simulation section 21 The gear grinding simulation unit 21 uses the computer 12 to execute a gear grinding simulation of the workpiece W using a threaded grinding wheel T based on the reference machining program BP described later, thereby estimating the tooth flank shape of the gear of the workpiece W.

[0021] An outline of the gear grinding simulation will be described with reference to Figures 4 and 5. The gear grinding simulation is performed using a surface grinding model. The type of surface grinding model is not particularly limited, but for example, the horizontal axis surface grinding model shown in Figure 4 can be used as the plane model. In this case, the principal component force vector ft and the thrust component force vector fn are expressed as follows using the specific grinding resistance Cp, table speed v, cutting depth (depth direction) Δ, thickness b, grinding wheel peripheral speed V, friction coefficient μ, and grinding wheel cutting edge tip half angle α, respectively.

[0022]

number

[0023] Furthermore, vΔb in equation (1) can be expressed as the volume Vcut removed per unit time of the workpiece model Mw by the grinding wheel model Mt. Therefore, in this simulation, it can be expressed as the following equation (2).

[0024]

number

[0025] Here, the removal volume Vcut per unit time is calculated based on the removal length Lcut, which is the distance between the workpiece definition points before and after the change. As shown in Figure 5, the removal volume Vcut per unit time can be calculated based on the first mesh area Sm1, which is the area of ​​the mesh that includes the workpiece definition point Pw before the change, the second mesh area Sm2, which is the area of ​​the mesh that includes the workpiece definition point Pw (Px) after the change, and the distance between the workpiece definition points before and after the change (i.e., the removal length Lcut). Details of the gear grinding simulation can be performed using the method described in JP 2023-33825 A.

[0026] Based on the removed volume Vcut calculated as described above, the grinding resistance when the workpiece W is ground with the threaded grinding wheel T can be calculated.

[0027] (2) Grinding resistance acquisition unit 22 The grinding resistance acquisition unit 22 acquires, using the reference machining program BP, a target grinding resistance TR, which is a component in a predetermined axial direction of the grinding resistance generated when performing grinding processing while rotating the threaded grinding wheel T and the workpiece W synchronously and feeding the threaded grinding wheel T relative to the workpiece W in the rotation axis direction Cg of the workpiece W, and which corresponds to the relative feed position of the threaded grinding wheel T.

[0028] The multiple axial directions of the gear grinding apparatus 1 will be described with reference to Fig. 6. In this embodiment, the X-axis, Y-axis, and Z-axis directions are defined with reference to the threaded grinding wheel T. Furthermore, the Xw-axis, Yw-axis, and Zw-axis directions are defined with reference to the workpiece W.

[0029] The Z-axis direction is the rotational axis direction Ct of the threaded grinding wheel T. The Y-axis direction is the direction in which the rotational axis direction Ct (Z-axis direction) of the threaded grinding wheel T approaches the Zw-axis direction, which is the rotational axis direction Cg of the workpiece W. The X-axis direction is the direction perpendicular to the Y-axis direction and the Z-axis direction.

[0030] As described above, the Zw direction is the rotational axis direction Cg of the workpiece W. The Xw axis direction is one of the directions perpendicular to the rotational axis direction Cg (Zw axis direction) of the workpiece W, and the Yw axis direction is a direction perpendicular to both the Zw axis direction and the Xw axis direction. In this embodiment, the feeding operation of the threaded grinding wheel T is performed in the rotational axis direction Cg (Zw axis direction) of the workpiece W. Therefore, in FIG. 6, the direction shown as the grinding wheel feeding direction is a direction parallel to the rotational axis direction Cg (Zw axis direction) of the workpiece W.

[0031] The predetermined axis direction is not particularly limited, and can be any one selected from the above-mentioned X-axis, Y-axis, Z-axis, Xw-axis, Yw-axis, and Zw-axis directions. By selecting the predetermined axis direction that has a high correlation between the waviness formed on the gear tooth surface and the grinding resistance, the waviness can be effectively reduced.

[0032] The waviness formed on the tooth flank of a gear will be explained with reference to Figure 7. Figure 7(a) shows one tooth Wa formed on a gear. In Figure 7(a), the tooth thickness direction is the s-axis direction, the cutting edge direction is the t-axis direction, and the tooth trace direction is the u-axis direction. As shown by the dashed-dotted line, one end of the tooth trace direction is the initial position us, and the other end is the final position ue. As shown by the dashed-two-dot line, one end of the tooth profile direction is the initial position ts, and the other end is the final position te.

[0033] As shown in Figure 7(b), the cutting edge Ta of the threaded grinding wheel T slides against the gear teeth Wa, grinding the gear teeth Wa. As the grinding process progresses, the grinding resistance changes, causing the load on the rotation of the threaded grinding wheel T to fluctuate. This causes mechanical deformations such as bending and twisting in the components of the gear grinding device 1, which affect the rotational phase between the threaded grinding wheel T and the workpiece W. For this reason, it is difficult to perfectly synchronize the threaded grinding wheel T and the workpiece W throughout the entire grinding cycle, which can result in errors in the tooth trace direction on the gear tooth flanks.

[0034] Figure 7(c) shows the relationship between the tooth flank shape and the length dimension in the tooth trace direction for the gear tooth flank. It can be seen that a relatively long-period waviness, indicated by the symbol L, is formed on the gear tooth flank. That is, as one end of the tooth trace direction, the initial position us, moves toward the other end, the final position ue, the tooth flank shape gradually increases, then gradually decreases, and then gradually increases again. This long-period waviness is the waviness caused by the change in grinding resistance described above. The long-period waviness is related to the static rigidity of the gear grinding device 1. In this embodiment, the long-period waviness can be reduced.

[0035] On the other hand, the blades Ta of the threaded grinding wheel T and the gear teeth Wa may be in sliding contact with three blades Ta of the threaded grinding wheel T and two teeth Wa of the gear, as shown in FIG. 7(b), or in sliding contact with two teeth Wa of the gear, as shown in FIG. 7(d), although not shown in detail. These two patterns alternate in the primary cycle of meshing between the blades Ta of the threaded grinding wheel T and the gear teeth Wa, resulting in a waviness in the tooth profile direction, as shown in FIG. 7(d). That is, as the tooth flank shape moves from the initial position ts at one end of the tooth profile direction to the final position te at the other end, the tooth flank shape gradually increases, then gradually decreases, and then gradually increases again. This waviness in the tooth profile direction may be applied to the present invention, or may be applied in consideration of the dynamic rigidity of the gear grinding apparatus 1.

[0036] Figure 8 shows a graph in which the grinding resistance when grinding a gear tooth surface with a threaded grinding wheel T is broken down into X-axis component, Y-axis component, and Z-axis component. The horizontal axis in Figure 8 represents the feed position of the grinding wheel in the direction of the rotation axis Cg (Zw-axis direction) of the workpiece W. The left end of the horizontal axis represents the initial position of the threaded grinding wheel T, and the right end of the horizontal axis represents the final position of the threaded grinding wheel T. However, the graph in Figure 8 shows the grinding resistance corresponding to long-period waviness by averaging short-period fluctuations caused by short-period waviness over a short period of time.

[0037] Regarding the Z-axis component, when the threaded grinding wheel T moves from its initial position, the Z-axis component of the grinding resistance decreases, reaches a minimum value, then increases again, reaches a constant value, increases again, reaches a maximum value, and then decreases.Compared to the long-period waviness in the tooth trace direction shown in Figure 7(c), it can be seen that the change in the Z-axis component of the grinding resistance is closely related to the long-period waviness in the tooth trace direction.

[0038] Changes in the Z-axis component of grinding resistance will be described with reference to Figure 9. Figures 9(a) to (c) show the areas of the workpiece W that were removed by the threaded grinding wheel T, estimated by a gear grinding simulation. The right and left tooth flanks refer to one and the other tooth flanks of one gear tooth Wa. In the figures, the shaded area indicates the area of ​​the gear tooth flank that was ground by the threaded grinding wheel T.

[0039] Figure 9(a) shows the grinding state of a gear in the early stages of the grinding process. In the early stages of grinding, when comparing the ground area of ​​the right tooth flank and the ground area of ​​the left tooth flank of a single tooth Wa, which are facing each other, the ground area of ​​the right tooth flank is larger than that of the left tooth flank. This suggests that the grinding resistance in the Z direction increased in the negative direction in the early stages of grinding. Strictly speaking, the grinding resistance is related to the volume removed by grinding (Vcut), not the ground area. However, the change in grinding resistance can be approximately measured by comparing the size of the removed area.

[0040] Figure 9(b) shows the grinding state of a gear in the middle stage of the grinding process. When comparing the ground area of ​​the right tooth flank and the ground area of ​​the left tooth flank for one tooth Wa in the middle stage of grinding, the ground area of ​​the right tooth flank and the ground area of ​​the left tooth flank are approximately equal. This is thought to be why the grinding resistance in the Z direction is balanced between the left and right sides in the middle stage of grinding, and therefore shows a constant value.

[0041] Figure 9(c) shows the grinding state of the gear at the final stage of the grinding process. When comparing the ground area of ​​the right tooth flank and the ground area of ​​the left tooth flank for one tooth Wa at the final stage of grinding, the ground area of ​​the left tooth flank is larger. This suggests that at the final stage of grinding, the grinding resistance in the Z direction has increased, in contrast to the initial stage.

[0042] Returning to Figure 8, as the threaded grinding wheel T moves from its initial position, the X-axis component of the grinding resistance increases, then remains at a substantially constant value, before decreasing again. On the other hand, as the Y-axis component of the grinding resistance decreases, then remains at a substantially constant value, before increasing again. In comparison with the long-period waviness in the tooth trace direction shown in Figure 7(c), it can be seen that the changes in the X-axis and Y-axis components of the grinding resistance are less closely related to the long-period waviness in the tooth trace direction than is the Z-axis component of the grinding resistance.

[0043] As described above, the relationship between the long-period waviness formed on the gear tooth surface and the axial direction is strongest in the rotational axis direction Ct (Z-axis direction) of the threaded grinding wheel T. Therefore, the rotational axis direction Ct (Z-axis direction) of the threaded grinding wheel T is most preferable as the predetermined axial direction. For this reason, in this embodiment, the rotational axis direction Ct (Z-axis direction) of the threaded grinding wheel T is selected as the predetermined axial direction, and Fz, which is the target grinding resistance TR related to the Z-axis direction, is obtained. This Fz is calculated according to the relative feed position in the rotational axis direction Cg (Zw-axis direction) of the workpiece W, and is therefore written as Fz(Zw).

[0044] The grinding resistance acquisition unit 22 may be configured to calculate the target grinding resistance TR using the grinding resistance calculated by executing the gear grinding simulation described above. Alternatively, the grinding resistance acquisition unit 22 may be configured to measure the target grinding resistance TR when the workpiece W is actually ground with the threaded grinding wheel T using the grinding resistance measured by a sensor (not shown).

[0045] (3) Rigidity acquisition section 23 Returning to FIG. 3 , the stiffness acquisition unit 23 acquires a target stiffness TS, which is a component of the stiffness of the gear grinding apparatus 1 in a predetermined axial direction. The stiffness acquisition unit 23 may be configured to calculate the target stiffness TS using the computer 12 by the finite element method. Alternatively, the stiffness acquisition unit 23 may be configured to actually measure the target stiffness TS using the stiffness of the gear grinding apparatus 1 measured by a sensor (not shown). Alternatively, the stiffness acquisition unit 23 may be configured to acquire the target stiffness TS by inputting catalog data for the gear grinding apparatus 1. The stiffness acquisition unit 23 can acquire stiffness in any direction, including the X-axis, Y-axis, and Z-axis. In this embodiment, the rotational axis direction Ct (Z-axis direction) of the threaded grinding wheel T is selected as the predetermined axial direction, and stiffness kz related to the Z-axis direction is acquired. Alternatively, the stiffness acquisition unit 23 may be configured to acquire dynamic stiffness as stiffness.

[0046] (4) Relative displacement calculation unit 24 The relative displacement calculation unit 24 calculates a target relative displacement TD, which is the relative displacement between the workpiece W and the threaded grinding wheel T in a predetermined axial direction, based on the target grinding resistance TR and the target stiffness TS for each relative feed position of the threaded grinding wheel T. The target displacement calculation unit can calculate the target displacement in any of the X-, Y-, and Z-axis directions. In this embodiment, based on Hooke's law related to static stiffness, the rotational axis direction Ct (Z-axis direction) of the threaded grinding wheel T is selected as the predetermined axial direction as shown in the following equation (3), and Δz, which is the target relative displacement TD related to the Z-axis direction, is obtained. Furthermore, if the stiffness acquisition unit 23 acquires dynamic stiffness, the relative displacement calculation unit 24 may be configured to acquire a velocity term in the predetermined axial direction in addition to the target relative displacement TD.

[0047]

number

[0048] (5) Corrected momentum calculation unit 25 The correction momentum calculation unit 25 calculates the correction momentum CM for the reference operation of the gear grinding device 1 based on the reference processing program BP so as to reduce the target relative displacement TD for each relative feed position of the threaded grinding wheel T in the rotation axis direction Cg (Zw axis direction) of the workpiece W.

[0049] The corrective momentum calculation unit 25 can calculate the corrective momentum CM in any direction, including the X-axis direction, Y-axis direction, Z-axis direction, Xw-axis direction, Yw-axis direction, and Zw-axis direction. In this embodiment, based on Hooke's law related to static stiffness, A(Zw), which is the corrective momentum CM in the rotational axis direction Cg (Zw-axis direction) of the workpiece W, is calculated as shown in the following equation (4). The corrective momentum calculation unit 25 may also be configured to calculate the corrective momentum CM related to dynamic stiffness.

[0050]

number

[0051] The right side of equation (4) is an equation for converting the relative displacement in the Z-axis direction between the workpiece W and the threaded grinding wheel T into the rotation angle of the workpiece W using the lead of the threaded grinding wheel T, the number of threads Ng of the threaded grinding wheel T, and the number of teeth Nw of the workpiece W. This allows A(Zw), which is the corrected momentum CM of the workpiece W in the rotational axis direction Cg (Zw axis), to be calculated.

[0052] (6) The corrected machining program creating unit 26 creates the corrected machining program CP by adding the corrected momentum CM to the reference machining program BP. However, the corrected machining program creating unit 26 may be omitted.

[0053] (7) Grinding control unit 27 The grinding control unit 27 grinds the workpiece W with the threaded grinding wheel T based on the corrected machining program CP to generate a gear. However, the grinding control unit 27 may also be configured to grind the workpiece W with the threaded grinding wheel T based on the reference machining program BP and the corrected momentum CM to generate a gear.

[0054] The corrected machining program CP will be explained with reference to Figures 10 and 11. First, the problems with the conventional technology will be explained again with reference to Figure 10. Figure 10(a) shows the target shape when machining the tooth flank of a gear in the conventional technology. In the conventional technology, the reference machining program BP was created with the goal of maintaining a constant tooth flank shape in the tooth trace direction from the initial position us to the final position ue.

[0055] Figure 10(b) is a graph showing the change in grinding force in the grinding wheel axial direction relative to the feed position in the workpiece axial direction. Comparing Figure 10(a) and Figure 10(b), the start and end positions on the horizontal axis are different. This is because the horizontal axis in Figure 10(a) represents the tooth trace direction, while the horizontal axis in Figure 10(b) represents the grinding wheel feed position in the workpiece axial direction. To grind the initial position us in the tooth trace direction of the gear tooth flank, the tip of the threaded grinding wheel T must be positioned further away in the tooth trace direction than the initial position us. For this reason, the start position in Figure 10(b) is located to the left of the start position in Figure 10(a). On the other hand, to grind the final position ue in the tooth trace direction of the gear, the end of the threaded grinding wheel T must be moved beyond the final position ue in the tooth trace direction of the gear. For this reason, the end position in Figure 10(b) is located to the right of the end position in Figure 10(a).

[0056] Figure 10(c) shows the relationship between the shape of the tooth flank of a gear ground using conventional technology and the tooth trace direction. As mentioned above, the tooth flank of a gear ground using conventional technology has long-period waviness in the tooth trace direction. It is necessary to reduce this long-period waviness and bring it closer to the target shape shown in Figure 10(a).

[0057] As can be seen by comparing Figures 10(a) and 10(c) with Figure 10(b), the feed position of the threaded grinding wheel T is misaligned with the tooth trace position of the gear, making it difficult to accurately control the feed position of the threaded grinding wheel T for long-period waviness formed in the tooth trace direction.

[0058] Next, the principles of the gear grinding method according to this embodiment will be described with reference to Fig. 11. Fig. 11(a) shows the gear tooth flank shape assumed by the corrected machining program CP, which is created in this embodiment by taking into account the corrected momentum CM. For the tooth flank shape shown in Fig. 10(c), the program is created so that the portions with large thicknesses in the tooth thickness direction are ground to become thinner, and the portions with small thicknesses in the tooth thickness direction are ground to become thicker.

[0059] Figure 11(b) is a graph showing the change in grinding resistance in the grinding wheel axis direction relative to the feed position in the workpiece axis direction when a gear is ground based on the corrected machining program CP. When additional motion is applied, strictly speaking, the grinding resistance changes. However, since the change in the cutting depth due to the additional motion is minute compared to the cutting depth of the grinding wheel into the workpiece W, the change in grinding resistance is sufficiently small.

[0060] Fig. 11(c) is an example of a graph showing the relationship between the additional momentum of the axial rotation angle of the workpiece W and the feed position of the threaded grinding wheel in the axial direction of the workpiece W based on the correction machining program CP. The shape of the graph in Fig. 11(c) is, for example, drawn in a shape that is like the graph in Fig. 11(b) turned upside down, but is not particularly limited thereto.

[0061] In this embodiment, a corrected machining program CP is created based on the grinding resistance shown in Figure 11(b) to form the tooth flank shape shown in Figure 11(a), and a gear is ground based on this corrected machining program CP while taking into account the corrected momentum CM shown in Figure 11(c). This results in a gear tooth flank with highly accurate reduced long-period waviness, as shown in Figure 11(d). However, the tooth flank shape shown in Figure 11(a) is merely an example, and the tooth flank shape targeted by the corrected machining program CP is not limited to Figure 11(a).

[0062] (8) Storage section 28 3, the storage unit 28 can be any storage medium such as a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk drive, a USB (Universal Serial Bus) memory, etc. The storage unit 28 stores a reference machining program BP, a target grinding resistance TR, a target stiffness TS, a target relative displacement TD, a correction momentum CM, and a correction machining program CP.

[0063] The reference machining program BP is a machining program that serves as a reference for grinding the gear tooth surface. Typically, it is a machining program that sets the gear tooth surface shape shown in Figure 10(a) as the target shape.

[0064] The target grinding resistance TR is a grinding resistance acquired by the grinding supply acquisition unit. Specifically, the target grinding resistance TR is a component in a predetermined axis direction of the grinding resistance generated when performing grinding using the reference machining program BP while synchronously rotating the threaded grinding wheel T and the workpiece W and feeding the threaded grinding wheel T relative to the workpiece W in the rotation axis direction Cg of the workpiece W, and is defined according to the relative feed position of the threaded grinding wheel T.

[0065] The target stiffness TS is a component of the stiffness of the gear grinding device 1 in a predetermined axial direction.

[0066] The target relative displacement TD is the relative displacement between the workpiece W and the threaded grinding wheel T in a predetermined axial direction based on the target grinding resistance TR and the target stiffness TS for each relative feed position of the threaded grinding wheel T.

[0067] The correction momentum CM is a correction momentum CM for the reference operation of the gear grinding device 1 based on the reference machining program BP so as to reduce the target relative displacement TD for each relative feed position of the threaded grinding wheel T.

[0068] The corrected machining program CP is a machining program formed by adding the corrected momentum CM to the reference machining program BP.

[0069] 1.2 Operation of this mode The operation of this embodiment will be described with reference to Fig. 12. However, the operation of this embodiment is not limited to the following description.

[0070] 12 is a flowchart showing the operation of the gear grinding apparatus 1 according to this embodiment. When the gear grinding starting device is started, the gear grinding simulation unit 21 acquires the reference machining program BP from the storage unit 28 (S1).

[0071] Next, the gear grinding simulation unit 21 uses the computer 12 to perform a gear grinding simulation of the workpiece W with the threaded grinding wheel T based on the reference machining program BP (S2). Subsequently, the grinding resistance acquisition unit 22 acquires, based on the results of the gear grinding simulation, a target grinding resistance TR that is a component in the rotational axis direction Ct of the threaded grinding wheel T out of the grinding resistance generated when grinding is performed while rotating the threaded grinding wheel T and the workpiece W synchronously and feeding the threaded grinding wheel T relative to the workpiece W in the rotational axis direction Cg of the workpiece W (an example of a grinding resistance acquisition step).

[0072] Next, the stiffness acquisition unit 23 acquires the target stiffness TS, which is the component in the rotation axis direction Ct of the threaded grinding wheel T, out of the stiffness of the gear grinding device 1 (S3, an example of a stiffness acquisition step).

[0073] Next, the relative displacement calculation unit 24 calculates the target relative displacement TD, which is the relative displacement between the workpiece W and the threaded grinding wheel T in the rotational axis direction Ct of the threaded grinding wheel T, for each relative feed position of the threaded grinding wheel T based on the target grinding resistance TR and the target stiffness TS (S4, an example of a relative displacement calculation process).

[0074] Next, the correction momentum calculation unit 25 calculates the correction momentum CM for the reference operation of the gear grinding device 1 based on the reference machining program BP so as to reduce the target relative displacement TD for each relative feed position of the threaded grinding wheel T (S5, an example of a correction momentum calculation process).

[0075] Next, the corrected machining program creating unit 26 creates a corrected machining program CP by adding the corrected momentum CM to the reference machining program BP (S6).

[0076] Next, the grinding control unit 27 grinds the workpiece W with the threaded grinding wheel T based on the corrected machining program CP to generate a gear (S7, an example of the grinding step). This completes the operation of the gear grinding device 1.

[0077] 1.3 Effects of this form Next, the effects of this embodiment will be described. This embodiment is a gear grinding method in which a workpiece W is ground using a threaded grinding wheel T to generate a gear by operating a gear grinding apparatus 1 based on a processing program. The gear grinding method includes a grinding resistance acquisition step, a stiffness acquisition step, a relative displacement calculation step, a corrected momentum calculation step, and a grinding step. The grinding resistance acquisition step acquires, using a reference processing program BP, a target grinding resistance TR, which is a component in a predetermined axis direction of the grinding resistance generated when grinding is performed while synchronously rotating the threaded grinding wheel T and the workpiece W and feeding the threaded grinding wheel T relative to the workpiece W in the rotation axis direction Cg of the workpiece W. The target grinding resistance TR corresponds to the relative feed position of the threaded grinding wheel T. The stiffness acquisition step acquires a target stiffness TS, which is a component in the predetermined axis direction of the stiffness of the gear grinding apparatus 1. The relative displacement calculation step calculates a target relative displacement TD, which is the relative displacement between the workpiece W and the threaded grinding wheel T in a predetermined axial direction, for each relative feed position based on the target grinding resistance TR and the target stiffness TS. The corrected momentum calculation step calculates a corrected momentum CM for the reference operation of the gear grinding device 1 based on the reference machining program BP so as to reduce the target relative displacement TD for each relative feed position. The grinding step generates a gear by grinding the workpiece W with the threaded grinding wheel T based on the corrected machining program CP, which adds the corrected momentum CM to the reference machining program BP.

[0078] The gear machining apparatus according to this embodiment operates based on a machining program to grind a workpiece W using a threaded grinding wheel T to generate a gear. The gear machining apparatus includes a grinding resistance acquisition unit 22, a stiffness acquisition unit 23, a relative displacement calculation unit 24, a corrected momentum calculation unit 25, and a grinding control unit 27. The grinding resistance acquisition unit 22 acquires, using the reference machining program BP, a target grinding resistance TR, which is a component in a predetermined axis direction of the grinding resistance generated when grinding is performed while synchronously rotating the threaded grinding wheel T and the workpiece W and feeding the threaded grinding wheel T relative to the workpiece W in the rotation axis direction Cg of the workpiece W. The target grinding resistance TR corresponds to the relative feed position of the threaded grinding wheel T. The stiffness acquisition unit 23 acquires a target stiffness TS, which is a component in the predetermined axis direction of the stiffness of the gear grinding apparatus 1. The relative displacement calculation unit 24 calculates a target relative displacement TD, which is the relative displacement between the workpiece W and the threaded grinding wheel T in a predetermined axial direction, for each relative feed position based on the target grinding resistance TR and the target stiffness TS. The corrected momentum calculation unit 25 calculates a corrected momentum CM for the reference operation of the gear grinding device 1 based on the reference machining program BP so as to reduce the target relative displacement TD for each relative feed position. The grinding control unit 27 grinds the workpiece W with the threaded grinding wheel T based on the reference machining program BP and the corrected momentum CM to generate a gear.

[0079] According to this embodiment, the target relative displacement TD is calculated based on the target grinding resistance TR and the target stiffness TS. A corrective momentum CM is calculated to reduce this target relative displacement TD. Taking this corrective momentum CM into account, the workpiece W is ground with the threaded grinding wheel T to generate a gear. This eliminates the need to understand the relationship between the waviness of the tooth flank shape and the machining operation, making it possible to reduce the gear waviness with high precision.

[0080] However, in this embodiment, the rotation axis of the threaded grinding wheel T is selected as the predetermined axis direction for the target grinding resistance TR, the rotation axis of the threaded grinding wheel T is selected as the predetermined axis direction for the target stiffness TS, the rotation axis direction Cg of the workpiece W is selected as the predetermined axis direction for the target relative displacement TD, and the rotation angle of the workpiece W is selected as the corrected momentum CM, but this is not limitative and the predetermined axis direction and the axial direction of the corrected momentum CM can be selected arbitrarily. For example, the following combinations can be suitably used.

[0081] Alternatively, the rotation axis of the threaded grinding wheel T may be selected as the predetermined axis direction for the target grinding resistance TR, the rotation axis of the threaded grinding wheel T may be selected as the predetermined axis direction for the target stiffness TS, the rotation axis direction Cg of the workpiece W may be selected as the predetermined axis direction for the target relative displacement TD, and the rotation angle of the threaded grinding wheel T may be selected as the corrected momentum CM.

[0082] Alternatively, the X-axis direction may be selected as the predetermined axis direction for the target grinding resistance TR, the X-axis direction may be selected as the predetermined axis direction for the target stiffness TS, the X-axis direction may be selected as the predetermined axis direction for the target relative displacement TD, and the relative displacement in the X-axis direction may be selected as the corrected momentum CM.

[0083] Alternatively, the Y-axis direction may be selected as the predetermined axis direction for the target grinding resistance TR, the Y-axis direction may be selected as the predetermined axis direction for the target stiffness TS, the Y-axis direction may be selected as the predetermined axis direction for the target relative displacement TD, and the relative displacement in the Y-axis direction may be selected as the corrected momentum CM.

[0084] Furthermore, in the grinding resistance acquisition step according to this embodiment, the target grinding resistance TR is acquired by simulation using the computer 12. Since there is no need to actually grind the gear and measure the grinding resistance, the manufacturing costs of the gear can be reduced.

[0085] Furthermore, the predetermined axis direction in this embodiment is the rotational axis direction Ct of the threaded grinding wheel T. The shape of the long-period waviness formed on the tooth surface of the gear is significantly affected by the grinding resistance in the rotational axis direction Ct of the threaded grinding wheel T. In this embodiment, the corrected momentum CM is calculated based on the grinding resistance in the rotational axis direction Ct of the threaded grinding wheel T, so that the waviness on the tooth surface can be reduced with higher precision.

[0086] Furthermore, the correction momentum calculation step according to this embodiment calculates, as the correction momentum CM, at least one of a rotational angle correction amount for the workpiece W, a rotational angle correction amount for the threaded grinding wheel T, and a shift motion correction amount for the threaded grinding wheel T in the rotational axis direction Ct, based on the relationship between the relative position of the workpiece W and the threaded grinding wheel T in the rotational axis direction Ct of the threaded grinding wheel T and at least one of the rotational angle of the workpiece W, the rotational angle of the threaded grinding wheel T, and the shift motion of the threaded grinding wheel T in the rotational axis direction Ct. According to this embodiment, by calculating and applying at least one of the rotational angle correction amount for the workpiece W, the rotational angle correction amount for the threaded grinding wheel T, and the shift motion correction amount for the rotational axis direction Ct of the threaded grinding wheel T, waviness of the tooth flank can be reduced.

[0087] In addition, the specified axial direction in this embodiment includes the rotational axis direction Ct of the threaded grinding wheel T and a direction perpendicular to the rotational axis direction Ct of the threaded grinding wheel T, and the grinding resistance acquisition process, stiffness acquisition process, relative displacement calculation process, and corrected momentum calculation process are performed for each of the rotational axis direction Ct of the threaded grinding wheel T and the direction perpendicular to the rotational axis direction Ct of the threaded grinding wheel T.

[0088] (Embodiment 2) Next, a second embodiment will be described with reference to Figures 13 to 15. Note that, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previous embodiments represent the same components as those in the previous embodiments, unless otherwise specified.

[0089] 13 is a block diagram of a control device 11 according to this embodiment. The gear grinding apparatus 1 of this embodiment differs from the first embodiment in that the control device 11 includes a tooth surface evaluation unit 29 and that a memory unit 28 stores predetermined conditions PC. The tooth surface evaluation unit 29 determines whether the degree of waviness of the gear tooth surface shape estimated by the gear grinding simulation unit 21 satisfies the predetermined conditions PC.

[0090] 14 shows a main flow of the operation of the gear grinding apparatus 1 according to this embodiment. When the gear grinding starting device is started, the gear grinding simulation unit 21 acquires the reference machining program BP from the storage unit 28 in S10.

[0091] Next, the gear grinding simulation unit 21 uses the computer 12 to perform a gear grinding simulation of the workpiece W with the threaded grinding wheel T based on the reference machining program BP (S11, an example of a gear grinding simulation step).

[0092] A flowchart of the gear grinding simulation is shown in Figure 15. When the gear grinding simulation (S11) is executed, the gear grinding simulation unit 21 increments the time t to t+1 in S110.

[0093] Next, the gear grinding simulation unit 21 determines whether the time t reaches the end time t end It is determined whether the time t is equal to or exceeds the end time t end If so (S111: Y), the gear grinding simulation ends.

[0094] On the other hand, time t is the end time t endOtherwise (S111: N), the gear grinding simulation unit 21 executes a gear grinding simulation of the workpiece W with the threaded grinding wheel T based on the reference machining program BP. In detail, the gear grinding simulation unit 21 calculates the interference portion between the workpiece W and the threaded grinding wheel T when grinding is performed while rotating the threaded grinding wheel T and the workpiece W synchronously and feeding the threaded grinding wheel T relative to the workpiece W in the direction of the rotation axis Cg of the workpiece W, and estimates the shape of the workpiece W by assuming that the interference portion corresponds to the ground portion (S112).

[0095] Next, the grinding resistance acquisition unit 22 calculates the grinding resistance at the portion where the workpiece W interferes with the threaded grinding wheel T in the gear grinding simulation (S113). In S113, the grinding resistance acquisition unit 22 calculates the grinding resistance in all directions (X-axis direction, Y-axis direction, Z-axis direction, Xw-axis direction, Yw-axis direction, and Zw-axis direction).

[0096] Next, the stiffness acquisition unit 23 acquires the stiffness of the gear grinding device 1 in all directions (S114).

[0097] Next, the relative displacement calculation unit 24 calculates the relative displacement between the workpiece and the threaded grinding wheel in all directions based on the grinding resistance calculated in S113 and the rigidity calculated in S114 (S115).

[0098] Next, the correction momentum calculation unit 25 calculates the correction momentum for the reference motion of the gear grinding device 1 based on the reference machining program in all directions (S116).

[0099] Next, the gear grinding simulation unit 21 adds the displacement of the machine tool to the motion of the gear grinding apparatus 1 at time t+1, which is the time next to time t (S117).

[0100] Next, the gear grinding simulation unit 21 stores the corrected motion of the gear grinding device 1 in the storage unit 28 (S118).

[0101] Next, in S111, the time t is set to the end time tend The processes of S110 to S118 are repeated until it is determined that the result is true (S111: Y). With the above, the gear grinding simulation (S11) is completed.

[0102] 14, the tooth flank evaluation unit 29 determines whether the degree of waviness of the tooth flank shape estimated by the gear grinding simulation satisfies a predetermined condition PC (S12). If the waviness of the tooth flank satisfies the predetermined condition PC (S12: Y), the grinding control unit 27 grinds the gear based on the reference machining program BP (S15).

[0103] On the other hand, if the waviness of the tooth surface does not satisfy the predetermined condition PC (S12: N), the correction momentum calculation unit 25 extracts the correction momentum CM related to the rotation angle of the rotation axis Cw of the workpiece W from the correction momentum in all directions calculated in S116 (S13).

[0104] Next, the corrected machining program creating unit 26 creates a corrected machining program CP by adding the corrected momentum CM to the reference machining program BP (S14).

[0105] Next, the processes of S11 to S14 are repeated until it is determined in S12 that the waviness of the tooth surface satisfies the predetermined condition PC (S12: Y).

[0106] As described above, if the waviness of the tooth surface does not satisfy the predetermined condition PC in S12 (S12: N), a correction processing program CP is created, and if it is subsequently determined in S12 that the waviness of the tooth surface satisfies the predetermined condition PC (S12: Y), the grinding unit grinds the gear based on the correction processing program CP (S15). This completes the operation of the gear grinding device 1.

[0107] Next, the effects of this embodiment will be described. The gear grinding apparatus 1 according to this embodiment further includes a gear grinding simulation process and a tooth flank evaluation process. The gear grinding simulation process uses a computer 12 to execute a gear grinding simulation of the workpiece W using a threaded grinding wheel T based on a reference machining program BP, thereby estimating the tooth flank profile of the gear of the workpiece W. The tooth flank evaluation process determines whether the degree of waviness of the tooth flank profile estimated by the gear grinding simulation process satisfies a predetermined condition PC. At least a portion of the grinding resistance acquisition process, stiffness acquisition process, and relative displacement calculation process are executed as part of the gear grinding simulation. If any of the grinding resistance acquisition process, stiffness acquisition process, and relative displacement calculation process remain, these remaining processes and the corrected momentum calculation process are executed if the predetermined condition PC is not satisfied, but are not executed if the predetermined condition PC is satisfied. The grinding process generates a gear based on the corrected machining program CP if the predetermined condition PC is not satisfied, and generates a gear based on the reference machining program BP if the predetermined condition PC is satisfied.

[0108] According to this embodiment, the gear grinding simulation process includes at least some of the grinding resistance acquisition process, stiffness acquisition process, and relative displacement calculation process. This allows the corrected momentum CM to be reflected in the gear grinding simulation process. As a result, the waviness of the gear tooth surface can be reduced with higher accuracy.

[0109] Furthermore, according to this embodiment, if the predetermined condition PC is not satisfied in the tooth surface evaluation step, the gear grinding simulation step executes the gear grinding simulation again using the corrected machining program CP as a new reference machining program BP. This allows the gear grinding simulation step to be executed based on the corrected machining program CP that takes into account the corrected momentum CM, making it possible to accurately estimate the shape of the gear tooth surface.

[0110] In this embodiment, the gear grinding simulation process is configured to execute a grinding resistance acquisition process, a stiffness acquisition process, and a relative displacement calculation process, but is not limited to this, and the gear grinding simulation process may be configured to execute any one of the grinding resistance acquisition process, stiffness acquisition process, and relative displacement calculation process. Furthermore, the gear grinding simulation process may be configured to execute part of the grinding resistance acquisition process, part of the stiffness acquisition process, or part of the relative displacement calculation process.

[0111] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention. [Explanation of symbols]

[0112] 1: gear grinding machine, 11: control device, 12: computer, 21: gear grinding simulation unit, 22: grinding force acquisition unit, 23: stiffness acquisition unit, 24: relative displacement calculation unit, 25: corrected momentum calculation unit, 26: corrected machining program creation unit, 27: grinding control unit, 28: memory unit, 29: tooth surface evaluation unit, BP: reference machining program, Cg: rotation axis direction of workpiece, CM: corrected momentum, CP: corrected machining program, Ct: rotation axis direction of threaded grinding wheel, PC: predetermined condition, S11: gear grinding simulation, T: threaded grinding wheel, Ta: threaded grinding wheel blade, TD: target relative displacement, TR: target grinding force, TS: target stiffness, W: workpiece, Wa: workpiece tooth

Claims

1. A gear grinding method for generating a gear by grinding a workpiece with a threaded grinding wheel by operating a gear grinding device based on a processing program, comprising: a grinding resistance acquisition step of acquiring a target grinding resistance, which is a component in a predetermined axial direction of grinding resistance that occurs when grinding is performed using a reference machining program while rotating the threaded grinding wheel and the workpiece synchronously and feeding the threaded grinding wheel relative to the workpiece in the rotational axis direction of the workpiece, and the target grinding resistance corresponds to a relative feed position of the threaded grinding wheel; a stiffness acquisition step of acquiring a target stiffness, which is a component in the predetermined axial direction of the stiffness of the gear grinding device; a relative displacement calculation step of calculating a target relative displacement, which is a relative displacement between the workpiece and the threaded grinding wheel in the predetermined axial direction, based on the target grinding resistance and the target stiffness for each of the relative feed positions; a correction momentum calculation step of calculating a correction momentum with respect to a reference operation of the gear grinding device based on the reference machining program so as to reduce the target relative displacement for each relative feed position; a grinding step of grinding the workpiece with the threaded grinding wheel to generate a gear, based on a corrected machining program in which the corrected momentum is added to the reference machining program.

2. 2. The gear grinding method according to claim 1, wherein the grinding resistance acquisition step acquires the target grinding resistance through a simulation using a computer.

3. 3. The gear grinding method according to claim 1, wherein the predetermined axis direction is a rotation axis direction of the threaded grinding wheel.

4. The corrected exercise amount calculation step includes: based on the relationship between the relative position of the workpiece and the threaded grinding wheel in the direction of the rotation axis of the threaded grinding wheel and at least one of the rotation angle of the workpiece and the rotation angle of the threaded grinding wheel, 4. The gear grinding method according to claim 3, wherein at least one of a rotational angle correction amount for the workpiece and a rotational angle correction amount for the threaded grinding wheel is calculated as the correction momentum amount.

5. the predetermined axial direction includes a rotational axis direction of the threaded grinding wheel and a direction perpendicular to the rotational axis direction of the threaded grinding wheel, 4. The gear grinding method according to claim 3, wherein the grinding resistance obtaining step, the stiffness obtaining step, the relative displacement calculating step, and the corrected momentum calculating step are performed for each of a direction of the rotation axis of the threaded grinding wheel and a direction perpendicular to the direction of the rotation axis of the threaded grinding wheel.

6. moreover, a gear grinding simulation step of estimating a tooth flank shape of a gear of the workpiece by executing a gear grinding simulation of the workpiece with the threaded grinding wheel based on the reference machining program using a computer; a tooth flank evaluation step of determining whether the degree of waviness of the tooth flank shape estimated by the gear grinding simulation step satisfies a predetermined condition, at least a part of the grinding resistance obtaining step, the stiffness obtaining step, and the relative displacement calculating step are executed as part of the gear grinding simulation, the grinding resistance obtaining step, the stiffness obtaining step, and the relative displacement calculating step (if any) remain, and the corrected momentum calculating step are executed when the predetermined condition is not satisfied, and are not executed when the predetermined condition is satisfied; 3. The gear grinding method according to claim 2, wherein the grinding step generates the gear based on the corrected machining program when the predetermined condition is not satisfied, and generates the gear based on the reference machining program when the predetermined condition is satisfied.

7. 7. The gear grinding method according to claim 6, wherein, if the predetermined condition is not satisfied in the tooth surface evaluation step, the gear grinding simulation step executes the gear grinding simulation again using the corrected machining program as a new reference machining program.

8. A gear grinding device that grinds a workpiece using a threaded grinding wheel to generate a gear by operating based on a machining program, a grinding resistance acquisition unit that acquires a target grinding resistance, which is a component in a predetermined axial direction of grinding resistance that occurs when performing a grinding process while rotating the threaded grinding wheel and the workpiece synchronously and feeding the threaded grinding wheel relative to the workpiece in the rotational axis direction of the workpiece using a reference machining program, and acquires the target grinding resistance that corresponds to a relative feed position of the threaded grinding wheel; a stiffness acquisition unit that acquires a target stiffness, which is a component in the predetermined axial direction of the stiffness of the gear grinding device; a relative displacement calculation unit that calculates a target relative displacement, which is a relative displacement between the workpiece and the threaded grinding wheel in the predetermined axial direction, based on the target grinding resistance and the target stiffness for each of the relative feed positions; a correction momentum calculation unit that calculates a correction momentum with respect to a reference operation of the gear grinding device based on the reference machining program so as to reduce the target relative displacement for each relative feed position; a grinding control unit that grinds the workpiece with the threaded grinding wheel based on the reference machining program and the corrected momentum to generate a gear.

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