Gear cutting tool design method and gear cutting tool design support device

Abstract

This design method for a gear machining tool (T) comprises: a step (S1) for acquiring gear specifications, tool specifications, and a tooth-profile-direction target modification amount, and performing temporary design of a tool edge shape of the gear machining tool on the basis the gear specifications, the tool specifications, and the tooth- profile-direction target modification amount; a step (S2) for acquiring a tooth-trace-direction target modification amount and determining a correction amount of a machining control element on the basis of the tooth-trace-direction target modification amount; a step (S33) for calculating a first tooth surface shape of the gear on the basis of the correction amount of the machining control element and the temporarily designed tool edge shape; a step (S35) for comparing the first tooth surface shape and a target tooth surface shape and calculating a first subject error in the tooth profile direction on the first tooth surface shape; and a step (S38) for performing main design of the tool edge shape on the basis of the tooth-profile-direction target modification amount and a first subject error modification amount for reducing the first subject error.

Description

[Technical Field]

[0001] The present invention relates to a method for designing a gear cutting tool and a design support device for a gear cutting tool. [Background technology]

[0002] When gears are subjected to load, deformation of the teeth or shafts can cause the meshing condition to deteriorate, resulting in noise. There is a growing demand for gears to achieve ideal meshing under load and to improve quietness, which requires modifying the tooth flank shape. The tooth flank shape modification factors for gears include, for example, tooth trace inclination (also called "tooth trace twist"), crowning, bias, pressure angle, and tooth profile roundness. Of these, tooth trace inclination, crowning, and bias are modification factors in the tooth trace direction, while pressure angle and tooth profile roundness are modification factors in the tooth profile direction (from the tooth root to the tooth tip).

[0003] Japanese Patent Application Laid-Open Publication No. 2021-11011 (Patent Document 1) describes a technique for applying an additional motion to a gear cutting tool to change the modification element in the tooth trace direction of the gear, which is expected to improve the accuracy of the gear teeth in the tooth trace direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-11011 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the above-mentioned technique, when a gear is machined by applying an additional motion to a gear machining tool, although the accuracy in the direction of the tooth trace of the gear is improved, a problem arises in that an error occurs in the shape of the gear in the direction of the tooth profile of the gear.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a design method for gear cutting tools that can correct errors related to the tooth trace direction and tooth profile direction of a gear, and a design support device for gear cutting tools. [Means for solving the problem]

[0007] One aspect of the present invention is A method for designing a gear cutting tool for machining gear teeth on a workpiece by moving the workpiece and the gear cutting tool relative to each other while rotating the gear cutting tool and the workpiece synchronously, with an axis parallel to the central axis of the gear cutting tool forming a predetermined crossed-axis angle with respect to a central axis of the workpiece, comprising: acquiring gear specifications that are specifications of the gear, acquiring tool specifications that are specifications of the gear cutting tool, acquiring a target tooth profile direction modification amount that is a target value of a tooth profile direction modification element of a tooth flank shape of the gear, and provisionally designing a tool edge shape of the gear cutting tool based on the gear specifications, the tool specifications, and the target tooth profile direction modification amount; a step of acquiring a target modification amount in the tooth trace direction, which is a target value of a modification element in the tooth trace direction of the tooth flank shape, and determining a correction amount of a machining control element during a machining operation based on the target modification amount in the tooth trace direction; calculating a first tooth flank profile of the gear based on a correction amount of the processing control element and the temporarily designed tool blade profile; comparing the calculated first tooth flank profile with a target tooth flank profile included in the gear specifications, and calculating a first target error in the tooth profile direction of the first tooth flank profile; a step of finally designing the tool blade shape based on the tooth profile direction target modification amount and a first object error modification amount for reducing the first object error; The present invention relates to a method for designing a gear cutting tool having the above-mentioned features.

[0008] Another aspect of the present invention is A design support device for a gear cutting tool that processes gear teeth on a workpiece by moving the workpiece and the gear cutting tool relative to each other while rotating the gear cutting tool and the workpiece synchronously, with an axis parallel to the central axis of the gear cutting tool forming a predetermined crossed axis angle with respect to a central axis of the workpiece, comprising: a gear specification acquisition unit that acquires gear specifications that are specifications of the gear; a tool specification acquisition unit that acquires tool specifications that are specifications of the gear cutting tool; a tooth profile direction target modification amount acquisition unit that acquires a tooth profile direction target modification amount, which is a target value of a tooth profile direction modification element of the tooth flank shape of the gear; a provisional design unit that provisionally designs a tool blade shape of the gear cutting tool based on the gear specifications, the tool specifications, and the tooth profile direction target modification amount; a tooth trace direction target modification amount acquisition unit that acquires a tooth trace direction target modification amount, which is a target value of a tooth trace direction modification element of the tooth flank shape; a correction amount determination unit that determines a correction amount of a machining control element during a machining operation based on the tooth trace direction target modification amount; a first tooth flank form calculation unit that calculates a first tooth flank form of the gear based on a correction amount of the processing control element and the temporarily designed tool blade form; a first object error calculation unit that compares the calculated first tooth flank profile with a target tooth flank profile included in the gear specifications and calculates a first object error in the tooth profile direction of the tooth flank profile; a final design unit that final designs the tool blade shape based on the tooth profile direction target modification amount and a first object error modification amount for reducing the first object error; The present invention relates to a design support device for gear cutting tools, which is equipped with the above. [Effects of the Invention]

[0009] According to one and other aspects of the present invention, the tool cutting edge shape of the gear cutting tool T is finally designed based on a first objective error modification amount for reducing a first objective error that occurs by correcting a processing control element during a processing operation based on the target modification amount in the tooth trace direction. This makes it possible to suppress errors in the gear tooth flank shape in the tooth profile direction, even when the processing control element is corrected based on the target modification amount in the tooth trace direction.

[0010] It should be noted that the reference symbols in parentheses in the claims indicate the correspondence with the specific means described in the embodiments to be described later, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing a processing device according to a first embodiment. [Figure 2] FIG. 1 is a diagram showing a workpiece and a gear cutting tool in gear skiving processing when a crossed-axis angle is set, viewed in the radial direction of the gear cutting tool. [Figure 3] A view of Figure 2 viewed in the direction of the central axis of the gear cutting tool. [Figure 4] FIG. 10 is a diagram illustrating the operation of gear skiving, as viewed in the radial direction of the gear cutting tool. [Figure 5] 4 viewed in the direction of the central axis of the machining tool. [Figure 6] FIG. 1 is a view of a workpiece and a gear cutting tool in gear skiving processing when an offset angle is set, viewed in the radial direction of the gear cutting tool. [Figure 7] FIG. 10 is a diagram showing the amount of crowning correction of the correction element. [Figure 8] FIG. 10 is a diagram showing the amount of bias correction of a correction element. [Figure 9] FIG. 10 is a diagram showing the amount of correction of the tooth trace inclination of the correcting element. [Figure 10] FIG. 10 is a diagram showing the amount of pressure angle modification of a correcting element. [Figure 11] FIG. 10 is a diagram showing the amount of correction of the tooth profile roundness of the correcting element. [Figure 12]FIG. 10 is a diagram showing a motion that changes the center distance between the central axis of a gear cutting tool and the central axis of a workpiece in a parabolic manner relative to the position of the face width. [Figure 13] FIG. 10 is a diagram showing a movement for linearly changing the cross-axis angle between the central axis of the gear cutting tool and the central axis of the workpiece relative to the position of the tooth width. [Figure 14] 10 is a diagram showing a movement in which the rotation angle of the workpiece relative to the rotation angle of the gear cutting tool is changed linearly relative to the position of the face width; FIG. [Figure 15] FIG. 10 is a diagram showing the correlation between the amount of change in the Y-axis and the amount of crowning modification, the correlation between the amount of change in the Y-axis and the amount of bias modification, and the correlation between the amount of change in the Y-axis and the amount of tooth trace inclination modification. [Figure 16] FIG. 10 is a diagram showing the correlation between the amount of change in the B axis and the amount of crowning modification, the correlation between the amount of change in the B axis and the amount of bias modification, and the correlation between the amount of change in the B axis and the amount of tooth trace inclination modification. [Figure 17] FIG. 10 is a diagram showing the correlation between the amount of change in the Cw axis and the amount of crowning modification, the correlation between the amount of change in the Cw axis and the amount of bias modification, and the correlation between the amount of change in the Cw axis and the amount of tooth trace inclination modification. [Figure 18] FIG. 10 is a diagram showing the correlation between the amount of change in the X and Y axes and the amount of crowning modification, the correlation between the amount of change in the X and Y axes and the amount of bias modification, and the correlation between the amount of change in the X and Y axes and the amount of tooth trace inclination modification. [Figure 19] FIG. 1 is a diagram showing the configuration of a design support apparatus according to a first embodiment. [Figure 20] 3 is a flowchart showing the operation of the design support apparatus and the main flow of a design method. [Figure 21] 10 is a flowchart showing a provisional design process for a tool blade shape. [Figure 22] 10 is a flowchart showing a correction amount determination process. [Figure 23] 10 is a flowchart showing the design process. [Figure 24] FIG. 10 is a perspective view showing a state in which a first target error is calculated based on a cross section perpendicular to the axis at one location in the center of the gear in the face width direction. [Figure 25] 10 is a flowchart showing a second error calculation process. [Figure 26]10 is a flowchart showing a redesign process. [Figure 27] 10 is a flowchart showing a correction amount redetermining process. [Figure 28] FIG. 11 is a perspective view showing a state in which a first target error is calculated based on an axis-perpendicular cross section at any one location in the face width direction of a gear in the second embodiment. [Figure 29] FIG. 11 is a perspective view showing a state in which a first target error is calculated based on axis-perpendicular cross sections at multiple locations in the face width direction of a gear in the third embodiment. [Figure 30] FIG. 11 is a perspective view showing a state in which a first target error is calculated based on the entire range in the face width direction of a gear in the fourth embodiment. [Figure 31] FIG. 13 is a perspective view showing a state in which a first target error is calculated based on a partial range in the face width direction of a gear in the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Embodiment 1) 1. Gear processing equipment configuration A design method and design support device for a gear cutting tool (also referred to as a "gear skiving cutter") according to a first embodiment of the present invention is applied to the design of a gear cutting tool for machining a workpiece. The workpiece according to this embodiment is supported by a gear cutting device, and gear teeth are formed on the workpiece by the gear cutting tool attached to the gear cutting device.

[0013] The configuration of the gear cutting device will be described with reference to Fig. 1. The gear cutting device 1 of this embodiment cuts gear teeth on the workpiece W by moving the workpiece W and the gear cutting tool T relative to each other while rotating the gear cutting tool T and the workpiece W synchronously, with an axis parallel to the central axis RT of the gear cutting tool T at a predetermined cross-axis angle α with respect to the central axis RW of the workpiece W.

[0014] As shown in FIG. 1, the gear cutting device 10 is, for example, a five-axis machining center having three linear axes and two rotational axes as drive axes for changing the relative position and attitude of the workpiece W and the gear cutting tool T. In this embodiment, the gear cutting device 10 has three orthogonal linear axes (X-axis, Y-axis, and Z-axis) as linear axes, and B-axis and Cw-axis as rotational axes. In this embodiment, the B-axis is a rotational axis about the central axis RB of the rotary table 14, which is parallel to the Y-axis, and the Cw-axis is a rotational axis about the central axis RW of the workpiece W. The gear cutting device 10 also has a Ct-axis, which is a rotational axis about the central axis RT of the gear cutting tool T, and including the Ct-axis makes it a six-axis machining center.

[0015] The gear machining device 10 is equipped with a tool spindle 11 that supports a gear cutting tool T and is rotatable about the Ct axis, and is movable in the Y and Z axis directions. The gear machining device 10 also includes a workpiece spindle 12 that supports a workpiece W and is rotatable about the Cw axis, is rotatable about the B axis, and is movable in the X axis direction. In this embodiment, a case will be described in which gear teeth are machined on the workpiece W by gear skiving. Note that the configuration is not limited to the above, and the tool spindle 11 and workpiece spindle 12 may be configured to be movable relative to each other.

[0016] 2. Gear skiving Gear skiving will be described with reference to Figures 2, 3, 4, 5, and 6. As shown in Figures 2 and 3, gear skiving is performed by positioning the central axis RT of a gear cutting tool T at an intersecting axis angle α with an axis parallel to the central axis RW of a workpiece W. When viewed from the X-axis direction, the central axis RT of the gear cutting tool T and the central axis RW of the workpiece W are parallel. The center-to-center distance between the central axis RT of the gear cutting tool T and the central axis RW of the workpiece W is defined as D.

[0017] 4 and 5, the gear cutting tool T is fed in the direction of the central axis RW of the workpiece W relative to the workpiece W while synchronizing the rotation of the workpiece W about the central axis RW with the rotation of the gear cutting tool T about the central axis RT, thereby machining gear teeth on the workpiece W. In gear skiving, each tooth groove portion of the workpiece W is machined only once by the gear cutting tool T while the workpiece W makes one rotation.

[0018] The offset angle γ is shown in Figure 6. The offset angle γ is the angle when the gear cutting tool T and the processing point of the workpiece W are shifted in the circumferential direction of the workpiece W. The reference position where the offset angle γ is zero is the position of the gear cutting tool T corresponding to the processing point at which the center-to-center distance D is greatest when the central axis RT of the gear cutting tool T and the central axis RW of the workpiece W are parallel and viewed from a direction perpendicular to the central axis RW of the workpiece W (the X-axis direction in this embodiment) when the processing point is changed in the circumferential direction of the workpiece W.

[0019] 3. Tooth surface modification elements The tooth flank modification elements used to modify the shape of a gear tooth flank will be explained with reference to Figures 7 to 11. As shown in Figures 7 to 11, the shape modification elements of the tooth flank Gf of a gear tooth G include modification elements in the tooth trace direction and modification elements in the tooth profile direction. The modification elements in the tooth trace direction include crowning (Figure 7), bias (Figure 8), and tooth trace inclination (Figure 9). The modification elements in the tooth profile direction include pressure angle (Figure 10) and tooth profile radius (Figure 11). Here, crowning refers to making the center of the face width higher than both ends in the tooth trace direction. Bias refers to continuously changing the pressure angle in the tooth trace direction to give the tooth flank a twist.

[0020] As shown in Fig. 7, the crowning modification amount Mc is expressed as the distance through which the measurement diameter passes at the center position (in this embodiment, the center position of the face width) of the evaluation range Dc in the tooth trace direction on the tooth flank Gf of the tooth G. As shown in Fig. 8, the bias modification amount Mb is expressed as the difference between the pressure angles Mp1 and Mp2 at both end positions (in this embodiment, positions Db / 2 on both sides from the center of the face width) of the evaluation range Db in the tooth trace direction on the tooth flank Gf of the tooth G.

[0021] As shown in Figure 9, the tooth trace inclination adjustment amount Mh is expressed as the difference in height in the tooth trace direction between the two end positions of the evaluation range Dh in the tooth trace direction on the tooth surface Gf of the tooth G (in this embodiment, the position of one end surface of the tooth and the center position of the tooth width) of the measurement diameter.

[0022] As shown in Fig. 10, the pressure angle modification amount Mp is expressed by the inclination error in the tooth depth direction at the center position (in this embodiment, the center position of the face width) of the evaluation range Dp in the tooth trace direction on the tooth flank Gf of the tooth G. As shown in Fig. 11, the tooth profile roundness modification amount Mr is expressed by the amount of protrusion of the tooth profile error at the center position (in this embodiment, the center position of the face width) of the evaluation range Dr in the tooth trace direction on the tooth flank Gf of the tooth G.

[0023] 4. Basics of tooth surface modification methods Among the tooth flank shape modification elements, the pressure angle and tooth profile roundness are modifications in the tooth profile direction and are transcriptions of the tool cutting edge shape. That is, they can be modified using the cutting edge shape of the gear cutting tool T. Additionally, modification may be performed using tool specifications such as the number of flutes, addendum shift coefficient, helix angle, cutting edge angle, and rake angle. Meanwhile, among the tooth flank shape modification elements, crowning, bias, and tooth trace inclination are modifications in the tooth trace direction and are transcriptions of the motion trajectory of the gear cutting device 10. That is, they can be modified using the Cw-axis, B-axis, X-axis, and Y-axis, which are the processing control elements of the gear cutting device 10. Although the pressure angle and tooth profile roundness can also be modified using the processing control elements of the gear cutting device 10, in this embodiment they are modified based on the tool cutting edge shape (specifications) of the gear cutting tool T.

[0024] Specifically, crowning can be formed by moving the gear cutting tool 10 so that the center-to-center distance D (shown in FIGS. 3 and 5) between the central axis RT of the gear cutting tool T and the central axis RW of the workpiece W relative to the position of the face width changes parabolically as the gear cutter advances in the face width direction, as shown in Fig. 12. Therefore, crowning can be corrected by controlling the operation of the Y-axis in the gear cutting device 10.

[0025] As shown in Figure 13, the bias can be formed by linearly changing the cross-axis angle α between the central axis RT of the gear cutting tool T and the central axis RW of the workpiece W relative to the position of the face width as the gear moves in the face width direction. Therefore, the bias can be adjusted by controlling the operation of rotating the gear cutting tool T about an axis parallel to the Y axis. However, in the gear cutting device 10, the gear cutting tool T does not rotate, so the bias can be adjusted by controlling the operation of the B axis, which is the axis of rotation of the workpiece W (workpiece swivel angle (cross-axis angle α)).

[0026] Although not shown, the bias can also be formed by varying the offset angle γ, which is obtained when the gear cutting tool T and the machining point of the workpiece W are shifted in the circumferential direction of the workpiece W, as the offset angle progresses in the tooth width direction. This can be corrected by controlling the operation of the X-axis and Y-axis in the gear cutting device 10.

[0027] As shown in Fig. 14, the tooth trace inclination can be formed by linearly changing the rotation angle β of the workpiece W relative to the rotation angle of the gear cutting tool T relative to the position of the face width as it moves in the face width direction. Therefore, the tooth trace inclination can be corrected by controlling the operation of the Cw axis in the gear cutting device 10. Note that the horizontal axes in Figs. 12 to 14 represent the position of the face width of the gear cutting tool T and the machining point of the workpiece W, that is, from the position of the right tooth flank on one end face side of the tooth (machining start position) to the position of the right tooth flank on the other end face side of the tooth (machining end position).

[0028] 5. Correlation between modification elements and processing control elements Next, the correlation between each modification element and each processing control element will be explained with reference to Figs. 15 to 18. Here, the correlation between each modification element and each processing control element differs depending on the specifications of the gear cutting tool T. The tool specifications of the gear cutting tool T are determined based on the specifications of the gear to be processed on the workpiece W. Therefore, each correlation shown in Figs. 15 to 18 represents the correlation for a certain gear cutting tool T, and different gear cutting tools T will show different correlations. Furthermore, examples of modification elements include crowning, bias, and tooth trace inclination, which are modification elements in the tooth trace direction, and examples of processing control elements include the Y-axis, B-axis, Cw-axis, and offset angle γ (two synchronous axes consisting of the X- and Y-axes).

[0029] 15 shows the correlation between the Y-axis change ΔY and the crowning modification amount Mc, the correlation between the Y-axis change ΔY and the bias modification amount Mb, and the correlation between the Y-axis change ΔY and the tooth trace inclination modification amount Mh. Each correlation is calculated based on the error between the gear tooth flank form obtained by the gear cutting simulation and the reference tooth flank form when a gear cutting simulation is performed with only the Y-axis changed from the reference cutting control parameter.

[0030] For example, each correlation is calculated using a quadratic function to represent the correlation between the modifying element and the processing control element based on the gear tooth flank shape obtained by the gear cutting simulation. Specifically, the error between the gear tooth flank shape obtained by the gear cutting simulation and the tooth flank of an involute helicoid, which is the reference tooth flank shape, is calculated, and the correlation between the calculated error and the amount of change in the processing control element (Y axis) is calculated.

[0031] Specifically, first, multiple tooth flank shapes are calculated by gradually changing the Y-axis, a processing control element, using a gear cutting simulation. This process is repeated sequentially to calculate the overall tooth flank shape. Then, for the correlation, the modification amounts Mc, Mb, and Mh of crowning, bias, and inclination, which are modification elements in the tooth trace direction of each tooth flank shape, are calculated, and a graph is created that correlates the calculated modification amounts Mc, Mb, and Mh of crowning, bias, and inclination with the change ΔY of the Y-axis, a processing control element.

[0032] The change amount ΔY on the Y-axis includes multiple values ​​obtained by changing the value in the positive direction from the reference value and multiple values ​​obtained by changing the value in the negative direction from the reference value. As shown in Figure 15, changing the Y-axis can significantly change the crowning. However, changing the Y-axis also changes the bias and tooth trace inclination.

[0033] Gear cutting simulation is described in, for example, Japanese Patent Application Laid-Open No. 2017-144502. The reference cutting control elements are used to cut gears without crowning, bias, modified tooth inclination, pressure angle, or tooth profile rounding. The modified tooth inclination refers to the tooth inclination relative to the reference tooth inclination, which is a gear specification.

[0034] Figure 16 shows the correlation between the change in B-axis ΔB and the crowning modification amount Mc, the correlation between the change in B-axis ΔB and the bias modification amount Mb, and the correlation between the change in B-axis ΔB and the tooth trace inclination modification amount Mh. Each correlation is calculated based on the error between the tooth flank form of the gear obtained by the gear cutting simulation and the reference tooth flank form when a gear cutting simulation is performed with only the B-axis changed from the reference cutting control parameter. The change in B-axis ΔB is controlled by the workpiece rotation angle (crossed axes angle α).

[0035] A graph showing the relationship between the modification amounts Mc, Mb, and Mh for crowning, bias, and tooth trace inclination and the change amount ΔB on the B-axis, which is a processing control parameter, is created in substantially the same manner as the Y-axis described above. The change amount ΔB on the B-axis includes multiple values ​​obtained by changing the value in the positive direction from the reference value and multiple values ​​obtained by changing the value in the negative direction from the reference value. As shown in Figure 16, changing the B-axis can significantly change the bias. However, changing the B-axis also changes the crowning and tooth trace inclination.

[0036] Figure 17 shows the correlation between the Cw-axis change amount ΔCw and the crowning modification amount Mc, the correlation between the Cw-axis change amount ΔCw and the bias modification amount Mb, and the correlation between the Cw-axis change amount ΔCw and the tooth trace inclination modification amount. Each correlation is calculated based on the error between the gear tooth flank form obtained by the gear cutting simulation and the reference tooth flank form when a gear cutting simulation is performed with only the Cw-axis changed from the reference cutting control parameter. The Cw-axis change amount ΔCw is controlled by the workpiece rotation angle β.

[0037] A graph showing the relationship between the modification amounts Mc, Mb, and Mh for crowning, bias, and tooth trace inclination and the change amount ΔCw of the Cw axis, which is a processing control parameter, is created substantially in the same manner as the Y axis described above. The change amount ΔCw of the Cw axis includes multiple values ​​obtained by changing the Cw axis in the positive direction from the reference value and multiple values ​​obtained by changing the Cw axis in the negative direction from the reference value. As shown in Figure 17, changing the Cw axis can significantly change the tooth trace inclination. Note that changing the Cw axis results in almost no change in crowning and bias.

[0038] Figure 18 shows the correlation between the change in offset angle γ and each modification factor. Here, offset angle γ is the angle when the gear cutting tool T and the machining point of the workpiece W are shifted in the circumferential direction of the workpiece W. Therefore, offset angle γ can be expressed by synchronizing the X-axis and Y-axis. In other words, the change in offset angle γ can be expressed by the changes ΔX and ΔY caused by the two synchronized axes, the X-axis and the Y-axis. Hereinafter, the change in offset angle γ will be expressed as ΔX and ΔY.

[0039] 18 shows the correlation between the change ΔX,Y in the offset angle γ and the crowning modification amount Mc, the correlation between the change ΔX,Y in the offset angle γ and the bias modification amount Mb, and the correlation between the change ΔX,Y in the offset angle γ and the tooth trace inclination modification amount Mh. Each correlation is calculated based on the error between the gear tooth flank form obtained by the gear cutting simulation and the reference tooth flank form when a gear cutting simulation is performed with only the offset angle γ changed from the reference processing control parameter.

[0040] A graph showing the relationship between the modification amounts Mc, Mb, and Mh of crowning, bias, and tooth trace inclination and the change amounts ΔX and ΔY of the offset angle γ, which is a processing control parameter, can be created in a manner similar to the Y-axis described above. As shown in Figure 18, changing the offset angle γ can significantly change the bias. However, changing the offset angle γ also changes the crowning and tooth trace inclination.

[0041] As described above, each modification element and each processing control element influence each other. Therefore, even when modifying one modification element, the other modification elements are affected, and therefore modification of those other modification elements is necessary. In the above, each processing control element (Y-axis, B-axis, Cw-axis, offset angle γ) is changed independently, but multiple elements may be changed synchronously based on specified synchronization conditions. In this case, too, it is possible to obtain a correlation between the processing control elements and the modification elements.

[0042] 6. Calculation method for error from the reference tooth surface As described above, each correlation is calculated based on the error between the tooth flank shape of the gear when each processing control element is changed and the reference tooth flank shape. The reference tooth flank shape is, for example, an involute tooth flank. A method for calculating the error from the reference tooth flank is described, for example, in JP 2021-11011 A.

[0043] 7. Configuration of design support device 20 The configuration of the design support device 20 will be described with reference to Fig. 19. The design support device 20 is a device that can support machining of gear teeth by modifying the tooth flank shape. The design support device 20 can be, for example, an embedded system (microcomputer) such as a PLC (Programmable Logic Controller) or a CNC (Computerized Numerical Control) device, or it can also be a personal computer, a server, or the like.

[0044] 19, the design support device 20 includes a storage device 21 that stores gear specifications, which are the specifications of the gear, tool specifications, which are the specifications of the gear cutting tool T, target tooth profile direction modification amounts, which are target values ​​of tooth profile direction modification elements of the gear tooth flank shape, and target tooth trace direction modification amounts, which are target values ​​of tooth trace direction modification elements of the tooth flank shape. The design support device 20 includes a gear specification acquisition unit 22 that acquires the gear specifications from the storage device 21, a tool specification acquisition unit 23 that acquires the tool specifications from the storage device 21, a tooth profile direction target modification amount acquisition unit 24 that acquires the tooth profile direction target modification amount from the storage device 21, and a tooth trace direction target modification amount acquisition unit 25 that acquires the tooth trace direction target modification amount from the storage device 21. The tooth profile direction modification elements include at least one of pressure angle and tooth profile roundness, and the tooth trace direction modification elements include at least one of crowning, bias, and tooth trace inclination.

[0045] The provisional design unit 26 acquires gear specifications from the gear specification acquisition unit 22, acquires tool specifications from the tool specification acquisition unit 23, and acquires a target tooth profile direction modification amount from a tooth profile direction target modification amount acquisition unit 24. The provisional design unit 26 provisionally designs the tool blade shape of the gear cutting tool T based on the gear specifications, the tool specifications, and the target tooth profile direction modification amount.

[0046] The correction amount determination unit 27 acquires the tooth trace direction target modification amount from the tooth trace direction target modification amount acquisition unit 25. The correction amount determination unit 27 determines the correction amounts of the machining control elements during machining operation based on the tooth trace direction target modification amount acquisition unit 25. The machining control elements include at least one of the crossed axes angle α, the offset angle γ representing the position of the gear cutting tool T in the circumferential direction of the workpiece, the center-to-center distance D between the central axis of the workpiece and the central axis of the gear cutting tool T, and the relative rotational speeds of the workpiece and the gear cutting tool T.

[0047] The first tooth flank form calculation unit 28 acquires the temporarily designed tool blade form of the gear cutting tool T from the temporary design unit 26, and acquires the correction amounts of the machining control elements from the correction amount determination unit 27. The first tooth flank form calculation unit 28 calculates the first tooth flank form of the gear based on the temporarily designed tool blade form and the correction amounts of the machining control elements.

[0048] The first object error calculation unit 29 acquires the first tooth flank form from the first tooth flank form calculation unit 28, and acquires the target tooth flank form included in the gear specifications from the gear specification acquisition unit 22. The first object error calculation unit 29 compares the calculated first tooth flank form with the target tooth flank form, and calculates the first object error in the tooth profile direction of the tooth flank form.

[0049] The main design unit 30 acquires the first object error from the first object error calculation unit 29, and acquires the tooth profile direction target modification amount from the tooth profile direction target modification amount acquisition unit 24. The main design unit 30 performs a main design of the tool blade shape based on the tooth profile direction target modification amount and the first object error modification amount for reducing the first object error.

[0050] The second tooth flank form calculation unit 31 acquires the finally designed tool blade form from the final design unit 30, and acquires the correction amount of the machining control element from the correction amount determination unit 27. The second tooth flank form calculation unit 31 calculates the second tooth flank form of the gear based on the correction amount of the machining control element and the finally designed tool blade form.

[0051] The second object error calculation unit 32 acquires the calculated second tooth flank form from the second tooth flank form calculation unit 31, and acquires the target tooth flank form included in the gear specifications from the gear specification acquisition unit 22. The second tooth flank form calculation unit 31 compares the calculated second tooth flank form with the target tooth flank form, and calculates the second object error of the second tooth flank form.

[0052] The redesign unit 33 acquires the target modification amount in the tooth profile direction from the target modification amount acquisition unit 24, acquires the target modification amount in the tooth trace direction from the target modification amount acquisition unit 25, and acquires the second target error from the second target error calculation unit 32. The redesign unit 33 redesigns the tool cutting edge shape based on at least one of the target modification amount in the tooth profile direction and the target modification amount in the tooth trace direction, and the second target error modification amount for reducing the second target error.

[0053] The correction amount redetermining unit 34 acquires the target modification amount in the tooth profile direction from the target modification amount acquisition unit 24, acquires the target modification amount in the tooth trace direction from the target modification amount acquisition unit 25, and acquires the second target error from the second target error calculation unit 32. The correction amount redetermining unit 34 redetermines the correction amount of the processing control element based on at least one of the target modification amount in the tooth profile direction and the target modification amount in the tooth trace direction, and the second target error modification amount for reducing the second target error.

[0054] However, the design support device of this embodiment may include both the redesign unit 33 and the correction amount redetermination unit 34, or may include only one of them.

[0055] 8. Operation of the design support device 20 (design method) (1) Main routine Next, the operation and design method of the design support device 20 of this embodiment will be described. As shown in Fig. 20, when the design support device 20 is started, a temporary design process is executed to temporarily design the tool blade shape of the gear cutting tool T (S1: temporary design step). Next, a correction amount determination process is executed to determine the correction amount of the machining control element during the gear machining operation (S2: correction amount determination step). Next, a final design process is executed to finally design the tool blade shape of the gear cutting tool T (S3: final design step).

[0056] For a gear formed by machining a workpiece using a gear cutting tool T whose tool blade shape has been determined by executing this design process, a second object error calculation process is executed in which a second tooth flank shape formed on the gear is compared with a target tooth flank shape included in the gear specifications to calculate a second object error of the second tooth flank shape (S4: second object error calculation process). Next, a redesign process is executed in which the tool blade shape is redesigned based on the second object error (S5: redesign process). Furthermore, a correction amount redetermining process is executed in which the correction amount of the machining control element is redetermined based on the second object error (S6: correction amount redetermining process). However, the order of the redesign process (S5) and the correction amount redetermining process (S6) is not limited. Furthermore, both the redesign process (S5) and the correction amount redetermining process (S6) may be executed, or only one of them may be executed.

[0057] (2) Provisional design processing As shown in FIG. 21 , when the temporary design process is executed, the gear specification acquisition unit 22 acquires gear specifications from the storage device 21 (S11: gear specification acquisition step). The gear specifications include information on the shape, material, etc. of the gear teeth to be machined into the workpiece. Next, the tool specification acquisition unit 23 acquires tool specifications from the storage device 21 (S12: tool specification acquisition step). The tool specifications include information on the shape, material, etc. of the gear cutting tool T. Next, the tooth profile direction target modification amount acquisition unit 24 acquires the tooth profile direction target modification amount from the storage device 21 (S13: target modification amount acquisition step). Next, the temporary design unit 26 provisionally designs the tool blade shape of the gear cutting tool T based on the gear specifications, tool specifications, and tooth profile direction target modification amount (S14: temporary design step). Since the tool blade shape of the gear cutting tool T may be modified in the actual design process described later, the tool blade shape of the gear cutting tool T is provisionally designed. This completes the provisional design process for the tool blade shape.

[0058] (3) Correction amount determination process Next, a correction amount determination process (S2) is executed as shown in Fig. 22. A gear cutting simulation is used to calculate multiple tooth flank shapes when the Y-axis, one of the processing control elements, is changed (S21: tooth flank shape calculation step). Subsequently, based on the error between the gear tooth flank shape calculated by the gear cutting simulation and a reference tooth flank shape, a correlation between the change amount ΔY of the Y-axis and each modification element is calculated (S22: correlation calculation step).

[0059] Next, a gear cutting simulation is used to calculate multiple tooth flank shapes when the Cw axis, one of the processing control elements, is changed (S23: tooth flank shape calculation step). Next, based on the error between the tooth flank shape of the gear calculated by the gear cutting simulation and the reference tooth flank shape, the correlation between the change amount ΔCw of the Cw axis and each modification element is calculated (S24: correlation calculation step).

[0060] Next, a gear cutting simulation is used to calculate multiple tooth flank shapes when the B-axis, one of the processing control elements, is changed (S25: tooth flank shape calculation step). Next, based on the error between the tooth flank shape of the gear calculated by the gear cutting simulation and the reference tooth flank shape, the correlation between the change amount ΔY of the B-axis and each modification element is calculated (S26: correlation calculation step). Note that the order in which the correlations of the Y-axis, Cw-axis, and B-axis are calculated may be changed as appropriate.

[0061] Next, the correction amount determination unit 27 calculates the correction amount ΔYa for the Y axis (S27: correction amount calculation step). For example, the correction amount determination unit 27 calculates the correction amount ΔYa for the Y axis based on the target crowning modification amount and the correlation between the change amount ΔY for the Y axis and the crowning modification amount Mc (upper diagram in FIG. 15). The change amount ΔY for the Y axis when the crowning modification amount Mc in FIG. 15 becomes the target modification amount is set to the correction amount ΔYa for the Y axis.

[0062] Next, the correction amount determination unit 27 calculates the correction amount ΔBa for the B-axis (S28: correction amount calculation step). For example, the correction amount determination unit 27 calculates the correction amount ΔBa for the B-axis based on the target bias adjustment amount, the B-axis change amount ΔB and the bias adjustment amount Mb (middle diagram of FIG. 16), and the bias adjustment amount Mb for the Y-axis correction amount ΔYa (middle diagram of FIG. 15). For example, the correction amount Mb for the bias in FIG. 16 is determined so that the sum of the bias adjustment amount Mb for the Y-axis correction amount ΔYa (middle diagram of FIG. 15) and the bias adjustment amount Mb in FIG. 16 matches the target adjustment amount. Then, the change amount ΔB for the B-axis at the determined bias adjustment amount Mb in FIG. 16 is set as the correction amount ΔBa for the B-axis.

[0063] Next, the correction amount determination unit 27 calculates the correction amount ΔCwa for the Cw-axis (S29: correction amount calculation step). For example, the correction amount determination unit 27 calculates the correction amount ΔCwa for the Cw-axis based on the target modification amount of the tooth trace inclination, the change amount ΔCw of the Cw-axis and the modification amount Mh of the tooth trace inclination (lower diagram in FIG. 17), the modification amount Mh of the tooth trace inclination when the correction amount ΔYa of the Y-axis is set (lower diagram in FIG. 15), and the modification amount Mh of the tooth trace inclination when the correction amount ΔBa of the B-axis is set (lower diagram in FIG. 16). For example, the tooth trace inclination modification amount Mh in Fig. 17 is determined so that the sum of the tooth trace inclination modification amount Mh (lower diagram in Fig. 15) when the Y-axis correction amount ΔYa, the tooth trace inclination modification amount Mh (lower diagram in Fig. 16) when the B-axis correction amount ΔBa is equal to the target modification amount. Then, the change amount ΔCw of the Cw-axis when the determined tooth trace inclination modification amount Mh in Fig. 17 is set as the Cw-axis correction amount ΔCwa.

[0064] Next, the correction amount determination unit 27 calculates the modification amounts Mc', Mb', and Mh' of the crowning, bias, and tooth trace inclination (S30: modification amount calculation step). The modification amounts Mc', Mb', and Mh' of each modification element are calculated based on the Y-axis correction amount ΔYa, the B-axis correction amount ΔBa, and the Cw-axis correction amount ΔCwa, and their correlations. For example, the crowning modification amount Mc' is calculated as the sum of the crowning modification amount Mc when the Y-axis correction amount ΔYa is used (upper diagram in FIG. 15), the crowning modification amount Mc when the B-axis correction amount ΔBa is used (upper diagram in FIG. 16), and the crowning modification amount Mc when the Cw-axis correction amount ΔCwa is used (upper diagram in FIG. 17). The same applies to the modification amounts Mb' and Mh' of the bias and tooth trace inclination.

[0065] Next, the correction amount determination unit 27 determines whether the modification amounts Mc', Mb', Mh' of the crowning, bias, and tooth trace inclination are approximate to the respective target modification amounts (S31: determination step). When the modification amounts Mc', Mb', Mh' are not approximate to the respective target modification amounts (S31: N), the correction amount determination unit 27 returns to step S27 and repeats the above-mentioned process. For example, when the crowning modification amount Mc' deviates from the target modification amount, the correction amounts ΔYa, ΔBa, ΔCwa of the respective modification elements are calculated so that the deviation amount can be additionally corrected.

[0066] As described above, the correction amount determination unit 27 calculates the Y-axis correction amount ΔYa, the B-axis correction amount ΔBa, and the Cw-axis correction amount ΔCwa in this order. The reason for this is that, as shown in FIGS. 15 to 17, the changes in the correction amounts Mc, Mb, and Mh of the correction elements decrease in the order of the Y-axis, the B-axis, and the Cw-axis. That is, the B-axis is less influenced by the Y-axis, and the Cw-axis is less influenced by the Y-axis and the B-axis. Due to this relationship, even with simple calculations, the correction amounts Mc', Mb', and Mh' of the correction elements quickly reach the vicinity of their respective target correction amounts. That is, the number of repetitions of steps S27 to S31 can be reduced in determining the correction amounts ΔYa, ΔBa, and ΔCwa for the Y-axis, B-axis, and Cw-axis.

[0067] When the modification amounts Mc', Mb', Mh' approximate the target modification amounts in S31 (S31: Y), the correction amount determination unit 27 determines the correction amounts ΔYa, ΔBa, ΔCwa for the Y-axis, B-axis, and Cw-axis, which are the calculated machining control elements (S32: correction amount determination step). Therefore, the correction amounts ΔYa, ΔBa, ΔCwa for each modification element can be calculated by a very simple calculation. Here, the simple calculation means a calculation that is simpler than the calculation by gear machining simulation.

[0068] (4) This design process 23, the first tooth flank form calculation unit 28 calculates the first tooth flank form of the gear through a gear cutting simulation using the correction amounts ΔYa, ΔBa, and ΔCwa for the Y-axis, B-axis, and Cw-axis, which are the processing control elements determined by the correction amount determination unit 27 (S33: first tooth flank form calculation step). The first object error calculation unit 29 acquires the calculated first tooth flank form (S34: first tooth flank form acquisition step). The first object error calculation unit 29 compares the first tooth flank form with the target tooth flank form to calculate a first object error in the tooth profile direction of the first tooth flank form (S35: first object error calculation step). The first object error is an error in at least one of the pressure angle and the tooth profile roundness.

[0069] As shown in FIG. 24, the first symmetric error is calculated based on the shape of the tooth surface Gf in a cross section PA perpendicular to the axis at one location at the center position of the gear tooth G in the face width direction Wd.

[0070] Next, the main design unit 30 acquires the tooth profile direction target modification amount from the storage device 21 (S36: target modification amount acquisition step). The main design unit 30 calculates a first object error modification amount to reduce the first object error calculated by the first tooth flank form calculation unit 28 (S37: first object error modification amount calculation step). The main design unit 30 performs a final design of the tool blade shape of the gear cutting tool T by modifying the tool blade shape of the gear cutting tool T in the tooth profile direction based on the tooth profile direction target modification amount and the first object error modification amount (S38: main design step).

[0071] (5) Second target error calculation process 25, the second tooth flank form calculation unit 31 acquires the correction amounts ΔYa, ΔBa, and ΔCwa for the Y-axis, B-axis, and Cw-axis, which are the processing control elements determined by the correction amount determination unit 27 (S41: correction amount acquisition step), and acquires the tool blade shape of the gear cutting tool T finally designed by the final design unit 30 (S42: tool blade shape acquisition step).The second tooth flank form calculation unit 31 calculates the second tooth flank form of the gear by gear cutting simulation based on the correction amounts of the processing control elements and the finally designed tool blade shape (S43: second tooth flank form calculation step).

[0072] The second object error calculation unit 32 acquires the target tooth flank form included in the gear specifications from the storage device 21 (S44: target tooth flank form acquisition step). The second object error calculation unit 32 compares the second tooth flank form with the target tooth flank form to calculate the second object error in the second tooth flank form (S45: second object error calculation step). The second object error includes both or either an error in the tooth profile direction and an error in the tooth trace direction.

[0073] (6) Redesign process When a second objective error occurs with respect to the tooth profile direction modification element, the redesign unit 33 redesigns the tool blade shape by modifying the tool blade shape of the gear cutting tool T. As shown in FIG. 26 , the redesign unit 33 acquires a target tooth profile direction modification amount from the storage device 21 (S51: target modification amount acquisition step). The redesign unit 33 calculates a second objective error modification amount for reducing the second objective error with respect to the tooth profile direction modification element (S52: second objective error calculation step). The redesign unit 33 redesigns the tool blade shape by modifying the tool blade shape of the gear cutting tool T in the tooth profile direction based on the tooth profile direction target modification amount and the second objective error modification amount (S53: tool blade shape redesign step).

[0074] (7) Correction amount redetermining process The correction amount redetermining unit 34 redetermines the correction amount of the processing control element when a second target error occurs for the tooth trace direction modification element. As shown in Fig. 27, the correction amount redetermining unit 34 acquires a target tooth trace direction modification amount from the storage device 21 (S61: target modification amount acquisition step). The correction amount redetermining unit 34 calculates a second target error modification amount for reducing the second target error for the tooth trace direction modification element (S62: second target error calculation step). The correction amount redetermining unit 34 redetermines the correction amount of the processing control element based on the target tooth trace direction modification amount and the second target error modification amount (S63: correction amount redetermining step). This completes all processing.

[0075] 9. Working Example Next, a description will be given of an example in which this embodiment is applied to a specific gear cutting tool T. Table 1 shows the target modification amounts in the tooth profile direction and the tooth trace direction of the gear cutting tool T according to this example.

[0076] [Table 1]

[0077] In this example, the target modification elements in the tooth profile direction, namely, the pressure angle modification amount and the tooth profile roundness modification amount, are set to 0.0 μm, and the target modification elements in the tooth trace direction, namely, the tooth trace inclination modification amount, the crowning modification amount, and the bias modification amount, are set to 5.0 μm, 5.0 μm, and 10.0 μm, respectively.

[0078] A provisional design process for the tool blade shape is executed for the gear cutting tool T according to this example, thereby provisionally designing the tool blade shape (S1 in FIG. 20).

[0079] Next, a correction amount determination process is executed based on the target modification amount in the tooth trace direction to determine the correction amount of the machining control element during the machining operation (S2 in FIG. 20).

[0080] Next, a first tooth flank form of the gear is calculated based on the correction amounts of the machining control elements and the provisionally designed tool blade form (S33 in FIG. 23). The calculated first tooth flank form is compared with a target tooth flank form, and a first target error in the tooth profile direction of the first tooth flank form is calculated (S35 in FIG. 23).

[0081] As shown in Table 1, in this example, a first-objective error occurred for the target modification elements in the tooth profile direction. Specifically, the first-objective error for the pressure angle was 0.6 μm, and the first-objective error for the tooth profile roundness was 0.2 μm. On the other hand, the first-objective errors for the target modification elements in the tooth trace direction, such as the tooth trace inclination, crowning, and bias, were 0.0 μm.

[0082] When the machining control elements during the machining operation are corrected based on the target modification amount in the tooth trace direction, the correction changes the movement path of the gear cutting tool T during the machining operation. This changes the shape removed from the workpiece by the gear cutting tool T. As a result, it is thought that a first objective error occurs between the calculated first tooth flank form and the target tooth flank form in the tooth profile direction.

[0083] Next, the first object error correction amount for reducing the first object error is calculated for the pressure angle and the tooth profile roundness (S37 in FIG. 23).

[0084] For the pressure angle, the target modification amount in the tooth profile direction is 0.0 μm and the first object error is 0.6 μm, so the first object error modification amount is calculated to be -0.6 μm. For the tooth profile roundness, the target modification amount in the tooth profile direction is 0.0 μm and the first object error is 0.2 μm, so the first object error modification amount is calculated to be -0.2 μm.

[0085] Next, the tool blade shape of the gear cutting tool T is finally designed based on the tooth profile direction target modification amount and the first target error modification amount (S38 in FIG. 23).

[0086] Next, the second tooth flank form of the gear is calculated based on the correction amounts of the machining control elements and the tool blade shape of the finally designed gear cutting tool T (S43 in FIG. 25). The calculated second tooth flank form is compared with the target tooth flank form, and a second objective error in the second tooth flank form is calculated (S45 in FIG. 25). The second objective error may include both an error in the tooth profile direction and an error in the tooth trace direction, or it may include only one of them.

[0087] As shown in Table 1, no second object error occurred in this example. Specifically, the first object error for the pressure angle and the second object error for the tooth profile roundness were 0.0 μm, and the second object errors for the tooth trace inclination, crowning, and bias were 0.0 μm.

[0088] 10. Effects of this form In this embodiment, since no second target error occurred, the tool blade shape is not redesigned in the tool blade shape redesign process (S5 in Figure 20), and the correction amount is not redetermined in the correction amount redetermining process (S6 in Figure 20).

[0089] According to this example, the tool blade shape of the gear cutting tool T is finally designed based on a first objective error modification amount for reducing a first objective error that occurs by correcting a processing control element during a processing operation based on a target modification amount in the tooth trace direction. This makes it possible to suppress errors in the gear tooth flank shape in the tooth profile direction, even when a processing control element is corrected based on a target modification amount in the tooth trace direction.

[0090] Furthermore, according to this embodiment, the second tooth flank form of the gear is calculated based on the correction amount of the machining control element and the finally designed tool cutting edge form, and the calculated second tooth flank form is compared with the target tooth flank form to calculate a second objective error of the second tooth flank form. As a result, even if an unexpected error occurs in the second tooth flank form of the gear machined by the finally designed gear cutting tool T as a result of modifying the provisionally designed tool cutting edge form to the finally designed tool cutting edge form, the error can be calculated as the second objective error. This makes it possible to deal with even unexpected errors.

[0091] According to this aspect, when a second object error occurs, the tool blade shape is redesigned or the correction amount of the machining control element is redetermined based on the second object error correction amount for reducing the second object error. This makes it possible to suppress the occurrence of errors in the gear tooth flank shape when the tool blade shape is corrected from a provisionally designed one to an actually designed one.

[0092] (Embodiment 2) Next, a second embodiment will be described with reference to Fig. 28. As shown in Fig. 28, in the correction amount determination process (S2), the correction amount is determined based on the shape of the tooth surface Gf in an arbitrary cross section PA perpendicular to the axis of the gear tooth G in the face width direction Wd.

[0093] In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant explanations will be omitted.

[0094] According to this embodiment, for example, the first object error can be calculated based on a cross section perpendicular to the axis at one location that is particularly affected by errors in the face width direction Wd of the gear tooth G. This improves the calculation accuracy of the first object error.

[0095] (Embodiment 3) Next, a third embodiment will be described with reference to FIG. 29. As shown in FIG. 29, in this embodiment, the first object error is calculated based on the shapes of the tooth flanks Gf at multiple (two in this embodiment) axis-perpendicular cross sections PA1 and PA2 in the face width direction Wd of the gear tooth G (S35 in FIG. 23). In this embodiment, for example, the first object error can be calculated based on the average value of the errors at the two axis-perpendicular cross sections PA1 and PA2. According to this embodiment, by using the axis-perpendicular cross sections PA1 and PA2 at multiple locations as the reference, the calculation accuracy of the first object error can be improved.

[0096] (Embodiment 4) Next, a fourth embodiment will be described with reference to FIG. 30. As shown in FIG. 30, in this embodiment, a first object error is calculated from an error in the tooth profile direction calculated over the entire range in the face width direction Wd of the gear tooth G (S35 in FIG. 23). In this embodiment, for example, the first object error can be calculated using the average value of the error over the entire range in the face width direction Wd of the gear tooth G as a reference. According to this embodiment, by using the entire range in the face width direction Wd of the gear tooth G as a reference, the calculation accuracy of the first object error can be improved.

[0097] (Embodiment 5) Next, a fifth embodiment will be described with reference to Fig. 31. As shown in Fig. 31, in this embodiment, a first object error is calculated from an error in the tooth profile direction calculated in a partially continuous range A in the face width direction Wd of the gear tooth G (S35 in Fig. 23). In this embodiment, for example, the first object error can be calculated based on the range A that is particularly affected by the error in the face width direction Wd of the gear tooth G. This improves the calculation accuracy of the first object error.

Claims

1. A method for designing a gear cutting tool for machining gear teeth (G) on a workpiece (W) by moving the workpiece and the gear cutting tool relative to each other while rotating the gear cutting tool and the workpiece synchronously, with an axis parallel to a central axis (RT) of the gear cutting tool (T) at a predetermined crossed-axis angle (α) with respect to a central axis (RW) of the workpiece, comprising: a step (S1) of acquiring gear specifications that are specifications of the gear, acquiring tool specifications that are specifications of the gear cutting tool, acquiring a target tooth profile direction modification amount that is a target value of a tooth profile direction modification element of a tooth flank shape of the gear, and provisionally designing a tool blade shape of the gear cutting tool based on the gear specifications, the tool specifications, and the target tooth profile direction modification amount; a step (S2) of acquiring a target modification amount in the tooth trace direction, which is a target value of a modification element in the tooth trace direction of the tooth flank shape, and determining a correction amount of a machining control element during a machining operation based on the target modification amount in the tooth trace direction; a step (S33) of calculating a first tooth flank profile of the gear based on the correction amount of the processing control element and the temporarily designed tool blade profile; a step (S35) of comparing the calculated first tooth flank profile with a target tooth flank profile included in the gear specifications and calculating a first target error in the tooth profile direction of the first tooth flank profile; a step (S38) of finally designing the tool blade shape based on the tooth profile direction target modification amount and a first object error modification amount for reducing the first object error; A method for designing a gear cutting tool comprising:

2. a step (S43) of calculating a second tooth flank profile of the gear based on the correction amount of the processing control element and the finally designed tool blade profile; a step (S45) of comparing the calculated second tooth flank form with the target tooth flank form included in the gear specifications to calculate a second target error of the second tooth flank form; The method for designing a gear cutting tool according to claim 1, comprising:

3. 3. The method for designing a gear cutting tool according to claim 2, further comprising steps (S53, S63) of redesigning the tool blade shape or redetermining the amount of correction for the machining control element based on at least one of the target modification amount in the tooth profile direction and the target modification amount in the tooth trace direction, and a second target error modification amount for reducing the second target error.

4. 2. The method for designing a gear cutting tool according to claim 1, further comprising calculating the first symmetric error in the tooth profile direction in one cross section (PA) perpendicular to the axis in a face width direction (Wd) of the gear.

5. 5. The method for designing a gear cutting tool according to claim 4, further comprising calculating the first symmetric error in the tooth profile direction in a cross section perpendicular to the axis at one central location in the face width direction.

6. 2. The method for designing a gear cutting tool according to claim 1, wherein the first target error is calculated from errors in the tooth profile direction calculated at a plurality of cross sections (PA1, PA2) perpendicular to the axis in the face width direction of the gear.

7. 2. The method for designing a gear cutting tool according to claim 1, wherein the first target error is calculated from errors in the tooth profile direction calculated over an entire range in the face width direction of the gear.

8. 2. The method for designing a gear cutting tool according to claim 1, wherein the first target error is calculated from an error in the tooth profile direction calculated in a partial range (A) in the face width direction of the gear.

9. the tooth profile direction modification element includes at least one of a pressure angle and a tooth profile radius; The method for designing a gear cutting tool according to any one of claims 1 to 8, wherein the tooth trace direction modifying element includes at least one of crowning, bias, and tooth trace inclination.

10. The process control element to be corrected is: the axis crossing angle (α), an offset angle (γ) representing the position of the gear cutting tool in the circumferential direction of the workpiece; the center distance (D) between the central axis of the workpiece and the central axis of the gear cutting tool; the relative rotational speed between the workpiece and the gear cutting tool; The method for designing a gear cutting tool according to any one of claims 1 to 8, comprising at least one of the following:

11. A design support device (20) for a gear cutting tool that processes gear teeth (G) on a workpiece (W) by moving the workpiece and the gear cutting tool relative to each other while rotating the gear cutting tool and the workpiece synchronously, with an axis parallel to a central axis (RT) of the gear cutting tool (T) at a predetermined crossed-axis angle (α) with respect to a central axis (RW) of the workpiece, comprising: a gear specification acquisition unit (22) that acquires gear specifications that are specifications of the gear; a tool specification acquisition unit (23) that acquires tool specifications that are specifications of the gear cutting tool; a tooth profile direction target modification amount acquisition unit (24) that acquires a tooth profile direction target modification amount, which is a target value of a tooth profile direction modification element of the tooth flank shape of the gear; a provisional design unit (26) that provisionally designs a tool blade shape of the gear cutting tool based on the gear specifications, the tool specifications, and the tooth profile direction target modification amount; a tooth trace direction target modification amount acquisition unit (25) that acquires a tooth trace direction target modification amount, which is a target value of a tooth trace direction modification element of the tooth flank shape; a correction amount determination unit (27) that determines a correction amount of a machining control element during machining based on the tooth trace direction target modification amount; a first tooth flank shape calculation unit (28) that calculates a first tooth flank shape of the gear based on a correction amount of the processing control element and the temporarily designed tool blade shape; a first object error calculation unit (29) that compares the calculated first tooth flank profile with a target tooth flank profile included in the gear specifications and calculates a first object error in the tooth profile direction of the tooth flank profile; a final design unit (30) that final designs the tool blade shape based on the tooth profile direction target modification amount and a first target error modification amount for reducing the first target error; A design support device for gear cutting tools equipped with this.

12. a second tooth flank shape calculation unit (31) that calculates a second tooth flank shape of the gear based on the correction amount of the processing control element and the finally designed tool blade shape; a second object error calculation unit (32) that compares the calculated second tooth flank form with a target tooth flank form included in the gear specifications and calculates a second object error of the second tooth flank form; The design support device for gear cutting tools according to claim 11, comprising:

13. 13. The design support device for a gear cutting tool according to claim 12, further comprising: a redesign unit (33) that redesigns the tool blade shape, or a correction amount redetermining unit (34) that redetermines correction amounts for the machining control elements, based on at least one of the target modification amount in the tooth profile direction and the target modification amount in the tooth trace direction, and a second target error modification amount for reducing the second target error.

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