Gear grinding wheel and gear grinding device

Abstract

To provide a gear grinding wheel and a gear grinding device that can improve the machining accuracy of gear tooth surfaces.SOLUTION: There is provided a gear grinding wheel T, comprising a grinding blade 30, which is formed on an outer peripheral surface centered on a central axis of the gear grinding wheel T, configured to grind the tooth surfaces of a gear, and comprises a cutting edge surface 31, a cutting bottom surface 32 and a cutting side surface 33. The cutting edge surface 31 of the grinding blade 30 is formed in an hourglass shape with an outer diameter that gradually increases from a middle portion to both end portions in a grinding wheel axis direction Ct being an axial direction of the gear grinding wheel T. The cutting side surface 33 of the grinding blade 30 is formed differently in accordance with a position in the grinding wheel axis direction Ct.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, techniques for grinding gear tooth flanks using a gear grinding wheel are known, as described in Patent Document 1 (Japanese Patent No. 5705567) and Patent Document 2 (Japanese Patent Laid-Open Publication No. 53-44992). Patent Documents 1 and 2 describe techniques for grinding gear tooth flanks using a gear grinding wheel formed in an hourglass shape. When a cylindrical gear grinding wheel is used, the blade of the gear grinding wheel and the gear teeth theoretically contact each other at a single point. In contrast, when an hourglass-shaped gear grinding wheel is used, the blade of the gear grinding wheel and the gear teeth contact each other at multiple points. This was expected to improve gear processing efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5705567 [Patent Document 2] Japanese Patent Publication No. 53-44992 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned technology does not clearly describe the cutting edge shape of the gear grinding wheel, which has led to the problem that the cutting edge shape of the gear grinding wheel cannot sufficiently improve the machining accuracy of the gear tooth surface.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a gear grinding wheel and a gear grinding device that can improve the machining accuracy of gear tooth surfaces. [Means for solving the problem]

[0006] One aspect of the present invention is A gear grinding wheel, a grinding blade formed on an outer peripheral surface of the gear grinding wheel centered on a central axis, configured to grind a gear tooth surface, and having a cutting edge surface, a cutting bottom surface, and a cutting side surface; the cutting edge surface of the grinding blade is formed in an hourglass shape in which the outer diameter dimension gradually increases from a middle portion toward both ends in the grinding wheel axial direction, which is the axial direction of the gear grinding wheel, The cutting edge side surface of the grinding blade is formed differently depending on the position in the grinding wheel axis direction.

[0007] Another aspect of the present invention is A gear grinding machine comprising: The above gear grinding wheel, a control device configured to grind the tooth flank of the gear with the gear grinding wheel by rotating the gear and the gear grinding wheel synchronously while setting an axial direction of the gear and an axial direction of the grinding wheel at a predetermined crossing axis angle and controlling the relative positions of the gear and the gear grinding wheel. [Effects of the Invention]

[0008] According to one and other aspects of the present invention, the cutting edge side surface of the grinding blade is formed differently depending on the position in the grinding wheel axis direction, thereby enabling high-precision machining of the gear tooth surface.

[0009] As described above, according to the above aspects, it is possible to provide a gear grinding wheel and a gear grinding device that can improve the machining accuracy of gear tooth surfaces. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a gear grinding device. [Figure 2] FIG. 2 is a diagram showing the gear grinding device, as viewed from the left side of FIG. 1. [Figure 3] FIG. 2 is a diagram showing a first gear and a gear grinding wheel. [Figure 4] 1A and 1B are diagrams showing a cross section of a grinding blade as seen from the grindstone axis direction, showing a plurality of cross sections at different positions in the grindstone axis direction. [Figure 5] FIG. 2 is a diagram showing the cutting edge surface and the bottom surface of one grinding blade. [Figure 6] FIG. 2 is a diagram showing the intersection lines of one blade side surface and the other blade side surface with the grinding wheel pitch circle for one grinding blade. [Figure 7] FIG. 10 is a diagram showing angles obtained by excluding the influence of the helix angle and the crossed-axis angle of the first gear from the ridge line angles of one blade side surface and the other blade side surface of one grinding blade. [Figure 8] FIG. 10 is a diagram showing the corrected helix angle of one blade side surface and the corrected helix angle of the other blade side surface for one grinding blade. [Figure 9] FIG. 1 is a diagram showing the cutting edge width angle at a predetermined diameter of the grinding wheel pitch circle for one grinding edge. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment 1) 1. Gear grinding equipment 1 Embodiment 1 will be described with reference to Figures 1 to 3. A gear grinding device 1 according to this embodiment grinds the tooth flanks of a gear using a gear grinding wheel T. The gear grinding device 1 of this embodiment may be used in a finishing process after rough cutting and hardening the tooth flanks of a gear, or in a tooth polishing process after rough cutting and finishing by skiving the tooth flanks of a gear. It can be used in any process.

[0012] The gear grinding machine 1 includes a bed 2, an X-axis guide 3, a column 4, a Y-axis guide 5, a Y-axis slide 6, a rotating member 7, a Z-axis guide 8, a grinding wheel support member 9, a gear grinding wheel T, a workpiece support member 10, and a control device 11. The bed 2 is installed on an installation surface. The column 4 is guided by an X-axis guide 3 installed on the upper surface of the bed 2 and is installed so as to be movable in the X-axis direction (horizontal direction) relative to the bed 2. Although not shown in detail, the column 4 is driven by a ball screw mechanism, a linear motor, or the like.

[0013] The Y-axis slide 6 is guided by a Y-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 Y-axis direction (up and down) relative to the column 4. The rotation member 7 is provided on the Y-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.

[0014] 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.

[0015] The grinding wheel support member 9 supports the gear grinding wheel T rotatably around the C axis. The C axis coincides with the grinding wheel axis direction Ct of the gear grinding wheel T and is an axis parallel to the Z axis. The gear grinding wheel T has a spiral grinding blade that protrudes radially outward. The gear grinding wheel T may have a single-start thread or a multiple-start thread. In the case of a multiple-start thread, the gear grinding wheel T has multiple spiral grinding blades. The workpiece support member 10 is provided on the bed 2 and supports the workpiece W rotatably around the B axis.

[0016] The gear grinding machine 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 machine 1 is not limited to a six-axis machine. In this embodiment, the gear grinding machine 1 is configured so that the workpiece W can rotate about the B axis, the gear grinding wheel T can rotate about the A axis and the C axis, and the gear 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 grinding wheel axis direction Ct of the gear grinding wheel T. The B axis coincides with the axial direction Cg (central axis) of the workpiece W. The C axis coincides with the grinding wheel axis direction Ct (central axis) of the gear grinding wheel T.

[0017] The control device 11 is configured, for example, by a CPU (Central Processing Unit) or a PLC (Programmable Logic Controller). The control device 11 is configured to grind the tooth flank of the first gear with the gear grinding wheel T by rotating the first gear 21 and the gear grinding wheel T synchronously while controlling the relative positions of the first gear 21 and the gear grinding wheel T so that an axial direction Cg of the first gear 21 (described later) and a grinding wheel axial direction Ct of the gear grinding wheel T form a predetermined crossing axis angle θ.

[0018] The feed direction of the gear grinding wheel T may be only the direction in which the central axis of the workpiece W approaches the central axis of the gear grinding wheel T. In this case, when grinding the first gear 21, the control device 11 moves the gear grinding wheel T in a direction in which it approaches the first gear 21, thereby forming the tooth surface of the first gear 21.

[0019] The feed direction of the gear grinding wheel T may be a direction intersecting the direction in which the central axis of the workpiece W and the central axis of the gear grinding wheel T approach each other and a direction intersecting the direction in which the central axis of the workpiece W and the central axis of the gear grinding wheel T approach each other. The direction intersecting the direction in which the central axis of the workpiece W and the central axis of the gear grinding wheel T approach each other may be, for example, the direction of the central axis of the workpiece W or a direction along a predetermined diagonal angle with respect to the central axis of the workpiece W. The control device 11 moves the gear grinding wheel T in a direction in which it approaches the first gear 21 in a region in which the first gear 21 and the gear grinding wheel T do not contact each other. Next, the control device 11 moves the gear grinding wheel in a direction intersecting the direction in which the central axis of the workpiece W and the central axis of the gear grinding wheel T approach each other. This forms the tooth surface of the first gear 21.

[0020] As shown in FIGS. 1 and 2, the workpiece W according to this embodiment includes a shaft 20, a first gear 21, and a second gear 22. The shaft 20 is formed in a long cylindrical shape. The first gear 21 and the second gear 22 are formed side by side at an interval in the longitudinal direction of the shaft 20. In this embodiment, the diameter of the first gear 21 is smaller than the diameter of the second gear 22. However, the diameter of the first gear 21 may be the same as or larger than the diameter of the second gear 22. When the workpiece W is placed on the workpiece support member 10, the axis of the shaft 20 and the B axis are arranged parallel to each other.

[0021] In this embodiment, the gear grinding wheel T grinds the tooth flank of the first gear 21. However, the gear grinding wheel T may grind the tooth flank of the second gear 22, or may grind the tooth flank of the first gear 21 and the tooth flank of the second gear 22.

[0022] 3, the gear grinding wheel T and the first gear 21 are arranged such that the grinding wheel axis direction Ct of the gear grinding wheel T and the axial direction Cg (central axis direction) of the first gear 21 form a predetermined cross-axis angle θ. The cross-axis angle θ is not particularly limited and can be set to, for example, 45° or less, or any angle between 20° and 30°.

[0023] As shown in FIG. 3, the cutting edge width L1 of the gear grinding wheel T in the wheel axis direction Ct is larger than the face width L2 of the first gear 21.

[0024] 2. Gear grinding wheel T The shape of the gear grinding wheel T according to this embodiment will be described with reference to Figs. 4 to 9. The gear grinding wheel T according to this embodiment is formed in the shape of a helical gear. The gear grinding wheel T has a grinding blade 30 formed on the outer peripheral surface centered on the central axis of the gear grinding wheel T. The grinding blade 30 grinds the tooth surface of the first gear 21. As shown in Fig. 4, the grinding blade 30 has a cutting edge surface 31, a cutting bottom surface 32, and a cutting side surface 33.

[0025] 2.1 Drum-shaped shape FIG. 5 shows the cutting edge surface 31 and cutting edge bottom surface 32 of the grinding blade 30, with the radius of the gear grinding wheel T as the horizontal axis and the position in the wheel axis direction Ct of the gear grinding wheel T as the vertical axis. The radius values ​​of the gear grinding wheel T increase in the order of P0, P1, and P2. Regarding the wheel axis direction position P in FIG. 5, the center position of the gear grinding wheel in the wheel axis direction Ct is F, and the distance from the center position F to one side increases in the order of E, D, C, B, and A in the wheel axis direction Ct. Furthermore, the distance from the center position F to the other side increases in the order of G, H, I, J, and K.

[0026] As shown in Fig. 5, the cutting edge surface 31 of the grinding blade 30 is disposed on the outermost periphery centered on the central axis of the gear grinding wheel T. The cutting edge surface 31 of the grinding blade 30 is formed in an hourglass shape in which the outer dimensions gradually increase from the middle to both ends in the grinding wheel axial direction Ct, which is the axial direction of the gear grinding wheel T (see Fig. 3). In other words, with respect to the grinding wheel axial direction position P, the value of the grinding wheel radius indicating the cutting edge surface 31 increases with increasing distance from the central position F. The hourglass shape is formed with a predetermined curvature.

[0027] 5, the bottom surface 32 of the grinding blade 30 is formed so that the outer dimension gradually increases from the middle to both ends in the grinding wheel axis direction Ct. That is, as shown by the dashed line in FIG. 5, the value of the grinding wheel radius representing the bottom surface 32 increases with increasing distance from the center position F of the grinding wheel axis direction position P. The curvature of the bottom surface 32 may be the same as or different from the curvature of the cutting edge surface 31. However, the bottom surface 32 of the grinding blade 30 may be formed so that the outer dimension is constant in the grinding wheel axis direction Ct, or may be formed so that the outer dimension gradually decreases from the middle to both ends in the grinding wheel axis direction Ct.

[0028] 4 also shows the cross-sectional shape of the grinding blade 30 when the grinding wheel axial position P is at the center position F, the cross-sectional shape of the grinding blade 30 when the grinding wheel axial position P is at position D, and the cross-sectional shape of the grinding blade 30 when the grinding wheel axial position P is at position B, with respect to the grinding wheel axial direction Ct. The grinding wheel radius of the blade bottom surface 32 is formed to increase as the axial positions move away from the center position F, namely F, D, and B.

[0029] 2.2 Blade length The cutting edge side surface 33 of the grinding blade 30 includes a cutting edge height, which is the height from the cutting edge surface 31 to the cutting edge bottom surface 32, as one of the shape defining elements. The cutting edge height can be calculated as the difference between the grinding wheel radius of the cutting edge surface 31 and the grinding wheel radius of the cutting edge bottom surface 32 at a certain grinding wheel axial position P in FIG. 5. In this embodiment, the cutting edge height of the grinding blade 30 is formed to vary depending on the position in the grinding wheel axial direction Ct. However, the cutting edge height of the grinding blade 30 may be formed to be constant in the grinding wheel axial direction Ct.

[0030] 2.3 Twist angle The cutting edge side surface 33 of the grinding blade 30 includes a helix angle located at a predetermined diameter of the gear grinding wheel T as at least one of its shape-defining elements. The helix angle of the grinding blade 30 of the gear grinding wheel T in this embodiment is defined as the angle between the central axis of the gear grinding wheel T and a line tangent to a point on the cutting edge side surface 33 at the predetermined diameter, the line being perpendicular to a radial line passing through that point. In this embodiment, the helix angle is formed to vary depending on the position in the grinding wheel axial direction Ct. Also, in this embodiment, the helix angle is formed to be smallest in the middle part in the axial direction and gradually increase from the middle part toward both ends in the grinding wheel axial direction Ct.

[0031] The predetermined diameter is the diameter of the grinding wheel pitch circle Op at a predetermined position in the grinding wheel axial direction on the grinding blade 30. The value of the predetermined diameter can be set arbitrarily, and in this embodiment, for example, it is set to a predetermined grinding wheel radius P1 as shown in FIG. 4. The grinding wheel pitch circle Op is defined as the pitch circle that is tangent to the pitch circle of the post-machining shape of the first gear 21 at a predetermined position in the grinding wheel axial direction Ct on the grinding blade 30. The predetermined position in the grinding wheel axial direction on the grinding blade 30 is not particularly limited and can be any position. In this embodiment, it can be, for example, the center position F in the grinding wheel axial direction.

[0032] The helix angle of the grinding blade 30 in this embodiment is the sum of a reference helix angle and a correction helix angle, which will be described later.

[0033] The helix angle of the grinding blade 30 of the gear grinding wheel T of this embodiment will be described with reference to Figures 6 to 8. Figure 6 shows the intersection line between one blade side surface 33a and the specified diameter of one grinding blade 30 of the gear grinding wheel T at a position of a specified diameter of the gear grinding wheel T, and the intersection line between the other blade side surface 33b and the specified diameter. The horizontal axis of Figure 6 indicates the ridgeline angle at which the grinding blade 30 is positioned relative to the ridgeline angle of 0°, assuming that an arbitrary position of the specified diameter of the gear grinding wheel T is a ridgeline angle of 0°. The vertical axis of Figure 6 is the same as that of Figure 5, so redundant explanation will be omitted.

[0034] If no helix angle is set for the grinding blade 30, the intersection line between the side surface of the grinding blade 30 and the predetermined diameter will be a straight line parallel to the central axis of the gear grinding wheel T. In FIG. 6, the central axis of the gear grinding wheel T is the direction in which the vertical axis extends. The grinding blade 30 of this embodiment is inclined with respect to the vertical axis, and a helix angle is set. In FIG. 6, the helix angle of the grinding blade 30 is expressed as the angle between the vertical axis and a tangent at any point of the intersection line between the side surface of the grinding blade 30 and the predetermined diameter.

[0035] Fig. 7 is a graph obtained by subtracting from Fig. 6 the influence of the helix angle of the first gear 21 and the influence of the cross-axis angle θ between the axial direction of the first gear 21 and the axial direction of the gear grinding wheel T. In Fig. 7, if the helix angle of the gear grinding wheel T is set taking into consideration only the helix angle of the first gear 21 and the cross-axis angle θ between the axial direction of the first gear 21 and the axial direction of the gear grinding wheel T, the line corresponding to one blade side surface 33a of the grinding blade 30 and the line corresponding to the other blade side surface 33b of the grinding blade 30 will be a straight line extending along the central axial direction (direction of the vertical axis) of the gear grinding wheel T.

[0036] As described above, the helix angle of the gear grinding wheel T in this embodiment is set as the sum of the reference helix angle and the correction helix angle. In this embodiment, the correction helix angle of one blade side surface 33a of one grinding blade 30 is expressed as the angle between the vertical axis and a tangent line at any point to a line relating to one blade side surface 33a of the grinding blade 30 in Fig. 7. Furthermore, the correction helix angle of the other blade side surface 33b of one grinding blade 30 is expressed as the angle between the vertical axis and a tangent line at any point to a line relating to the other blade side surface 33b of the grinding blade 30 in Fig. 7.

[0037] FIG. 8 shows a graph relating to the relationship between the corrected helix angles set on one blade side surface 33a and the other blade side surface 33b of one grinding blade 30 of this embodiment and the position in the grindstone axis direction Ct.

[0038] The corrective helix angle formed on one blade side surface 33a of the grinding blade 30 of this embodiment is formed so as to gradually increase from one end position B in the grinding wheel axis direction Ct toward the other end position J. Moreover, the corrective helix angle formed on the other blade side surface 33b of the grinding blade 30 of this embodiment is formed so as to gradually decrease from one end position B in the grinding wheel axis direction Ct toward the other end position J.

[0039] 2.4 Blade thickness The blade side surface 33 of the grinding blade 30 in this embodiment includes, as at least one shape-defining element, a blade thickness located at a predetermined diameter of the gear grinding wheel T. In this embodiment, the blade thickness is formed to vary depending on the position in the grinding wheel axial direction Ct. Specifically, the blade thickness is formed to be smallest at the middle part in the grinding wheel axial direction Ct, and gradually increases from the middle part toward both ends in the grinding wheel axial direction Ct.

[0040] FIG. 9 shows the relationship between the position in the grinding wheel axis direction Ct and the cutting edge width angle for one grinding blade 30. The cutting edge width angle is defined as the difference between the ridge angle of one cutting edge side surface 33a and the ridge angle of the other cutting edge side surface 33b at a given diameter. As shown in FIG. 9, the cutting edge width angle is smallest at the center position F in the grinding wheel axis direction Ct and gradually increases from the center position F toward both ends (positions B and J) in the grinding wheel axis direction Ct. The cutting edge width angle shown in FIG. 9 indicates the distance between the line corresponding to one cutting edge side surface 33a of the grinding blade 30 and the line corresponding to the other cutting edge side surface 33b of the grinding blade 30 at a given grinding wheel axis direction position P, as shown in FIG. 7.

[0041] 3. Gear grinding Next, a method for grinding the workpiece W using the gear grinding device 1 of this embodiment will be described. However, the method for grinding the workpiece W is not limited to the following description.

[0042] First, the axial direction Cg of the first gear 21 of the workpiece W and the grinding wheel axial direction Ct of the gear grinding wheel T are aligned so that they form a predetermined cross-axis angle θ. The cross-axis angle θ can be set to 45° or less, for example, between 20° and 30°.

[0043] Next, the first gear 21 of the workpiece W and the gear grinding wheel T are rotated synchronously, and the relative positions of the first gear 21 and the gear grinding wheel T are controlled to grind the tooth flank of the first gear 21 with the gear grinding wheel T. In this state, at least one of the gear grinding wheel T and the first gear 21 is moved so as to reduce the relative axial distance between the gear grinding wheel T and the first gear 21, without moving the gear grinding wheel T relative to the first gear 21 in the axial direction Cg. In this case, the gear grinding wheel T may be moved, or the first gear 21 may be moved, or both the gear grinding wheel T and the first gear 21 may be moved. In this embodiment, the column 4 is moved in the X-axis direction along the X-axis guide 3. However, the gear grinding wheel T may also be moved relative to the first gear 21 in the axial direction Cg. In this manner, the tooth flank of the first gear 21 is formed.

[0044] 4. Effects of this form Next, the effects of this embodiment will be described. This embodiment relates to a gear grinding wheel T, which includes a grinding blade 30. The grinding blade 30 is formed on the outer circumferential surface of the gear grinding wheel T, centered on the central axis of the gear grinding wheel T. The grinding blade 30 is configured to grind the tooth flank of the first gear 21, and includes a cutting edge surface 31, a cutting bottom surface 32, and a cutting edge side surface 33. The cutting edge surface 31 of the grinding blade 30 is formed in an hourglass shape, with the outer diameter gradually increasing from the middle to both ends in the grinding wheel axis direction Ct, which is the axial direction of the gear grinding wheel T. The cutting edge side surface 33 of the grinding blade 30 is formed differently depending on the position in the grinding wheel axis direction Ct. The cutting edge side surface 33 of the grinding blade 30 is formed differently depending on the position in the grinding wheel axis direction Ct of the gear grinding wheel T. This allows the shape of the grinding blade 30 at the position where it contacts and processes the first gear 21 to be a shape suitable for forming the desired gear shape. As a result, the tooth surface of the first gear 21 can be machined with high precision.

[0045] Furthermore, the cutting edge side surface 33 of the grinding blade 30 according to this embodiment includes, as at least one shape defining element, a helix angle located at a predetermined diameter of the gear grinding wheel T, and the helix angle is formed to vary depending on the position in the grinding wheel axial direction Ct. Because the helix angle of the grinding blade 30 varies depending on the position in the grinding wheel axial direction Ct of the gear grinding wheel T, the tooth surface of the first gear 21 can be machined with higher precision.

[0046] Furthermore, the helix angle according to this embodiment is formed to be smallest in the middle of the grinding wheel axis direction Ct and gradually increase from the middle to both ends of the grinding wheel axis direction Ct. This prevents the portions of the grinding blade 30 near both ends of the grinding wheel axis direction Ct of the gear grinding wheel T from interfering with the tooth flank of the first gear 21. This allows the tooth flank of the first gear 21 to be machined with high precision.

[0047] Furthermore, the helix angle according to this embodiment is the sum of a reference helix angle and a correction helix angle. The reference helix angle is the sum of the helix angle of the first gear 21 and the acute angle formed by the axial direction Cg of the first gear 21 and the grinding wheel axial direction Ct of the gear grinding wheel T. The correction helix angle is formed differently depending on the position in the grinding wheel axial direction Ct. By forming the correction helix angle differently depending on the position in the grinding wheel axial direction Ct, the tooth flank of the first gear 21 can be formed with higher precision.

[0048] The corrective helix angle formed on one blade side surface 33a of the grinding blade 30 according to this embodiment is formed so as to gradually increase from one end to the other end in the grinding wheel axis direction Ct, and the corrective helix angle formed on the other blade side surface 33b of the grinding blade 30 is formed so as to gradually decrease from one end to the other end in the grinding wheel axis direction Ct. This enables the tooth surface of the first gear 21 to be formed with higher precision.

[0049] The bottom surface 32 of the grinding blade 30 according to this embodiment is formed so that the outer diameter gradually increases from the middle to both ends in the grinding wheel axis direction Ct. The side surface 33 of the grinding blade 30 includes a cutting edge height, which is the height from the bottom surface 32 to the cutting edge surface 31, as at least one of the shape defining elements. The cutting edge height is formed to vary depending on the position in the grinding wheel axis direction Ct.

[0050] A middle portion of the grinding blade 30 in the grinding wheel axis direction Ct of the gear grinding wheel T contacts the tooth flank of the first gear 21 approximately perpendicularly. Meanwhile, portions of the grinding blade 30 near both ends in the grinding wheel axis direction Ct of the gear grinding wheel T contact the tooth flank of the first gear 21 at an angle. Therefore, the cutting length of the grinding blade 30 varies depending on the position in the grinding wheel axis direction Ct of the gear grinding wheel T, allowing the tooth flank of the first gear 21 to be machined with higher precision.

[0051] The cutting edge side surface 33 of the grinding edge 30 according to this embodiment includes, as at least one shape defining element, a cutting edge thickness located at a predetermined diameter of the gear grinding wheel T. The cutting edge thickness is formed to vary depending on the position in the grinding wheel axial direction Ct. By forming the cutting edge thickness to vary depending on the position in the grinding wheel axial direction Ct, the tooth surface of the first gear 21 can be machined with higher precision.

[0052] The blade thickness in this embodiment is formed to gradually increase from the middle to both ends in the grindstone axis direction Ct, thereby enabling the tooth flank of the first gear 21 to be machined with even higher precision.

[0053] The width dimension of the gear grinding wheel T according to this embodiment in the wheel axis direction Ct is larger than the width dimension of the first gear 21 in the axial direction Cg.

[0054] This embodiment is a gear grinding device 1, which includes a gear grinding wheel T and a control device 11. The control device 11 is configured to grind the tooth surface of the first gear 21 with the gear grinding wheel T by rotating the first gear 21 and the gear grinding wheel T synchronously while controlling the relative positions of the first gear 21 and the gear grinding wheel T such that the axial direction Cg of the first gear 21 and the grinding wheel axial direction Ct of the gear grinding wheel T form a predetermined crossing axis angle θ.

[0055] Furthermore, the cutting edge width L1 of the gear grinding wheel T in the grinding wheel axis direction Ct of the gear grinding device 1 of this embodiment is larger than the face width L2 of the first gear 21. The cross-axis angle θ is set to 45° or less. The control device 11 is configured to grind the entire tooth surface of the first gear 21 by moving at least one of the gear grinding wheel T and the first gear 21 so as to reduce the relative axial distance between the gear grinding wheel T and the first gear 21 without moving the gear grinding wheel T relative to the first gear 21 in the axial direction.

[0056] According to this configuration, the entire tooth flank of the first gear 21 can be ground by moving the gear grinding wheel T in a direction that reduces the center-to-center distance between the gear grinding wheel T and the first gear 21. This eliminates the need for a process (so-called oscillation) of moving the gear grinding wheel T in a direction that does not change the center-to-center distance between the gear grinding wheel T and the first gear 21. As a result, the space required for the gear grinding wheel T to move when grinding the tooth flank of the first gear 21 can be reduced. This makes it possible, for example, to grind a workpiece W having multiple gears with a relatively short center-to-center distance, to prevent contact between the gear grinding wheel T and the other gears when grinding one of the multiple gears with the gear grinding wheel T. In this way, according to this embodiment, it is possible to machine a workpiece W having multiple gears with a short center-to-center distance.

[0057] Furthermore, since oscillation is no longer necessary, the wear on the blade of the gear grinding wheel T can be reduced, thereby extending the life of the gear grinding wheel T.

[0058] Furthermore, conventionally, when grinding a workpiece W having multiple gears with a relatively small center distance, skiving processing using a skiving tool has been performed. The gear grinding wheel T can be reused by truing or dressing even when the grinding blade 30 is worn. Therefore, the tool life is longer than that of a skiving tool. According to this embodiment, the tool life can be extended compared to the case of the skiving processing method.

[0059] 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]

[0060] 1: gear grinding device, 11: control device, 21: first gear, 22: second gear, 30: grinding blade, 31: cutting edge surface, 32: cutting bottom surface, 33: cutting edge side surface, 33a: one cutting edge side surface, 33b: other cutting edge side surface, Cg: axial direction of first gear, Ct: grinding wheel axial direction, L1: cutting edge width dimension of gear grinding wheel, L2: face width dimension of first gear, Op: grinding wheel pitch circle, P: position in the grinding wheel axial direction, T: gear grinding wheel, W: workpiece, θ: crossed axes angle

Claims

1. A gear grinding wheel, a grinding blade formed on an outer peripheral surface of the gear grinding wheel centered on a central axis, configured to grind a gear tooth surface, and having a cutting edge surface, a cutting bottom surface, and a cutting side surface; the cutting edge surface of the grinding blade is formed in an hourglass shape in which the outer diameter dimension gradually increases from a middle portion toward both ends in a grinding wheel axial direction, which is the central axial direction of the gear grinding wheel, A gear grinding wheel, wherein the blade side surface of the grinding blade is formed differently depending on the position in the wheel axis direction.

2. the cutting edge side of the grinding blade includes, as at least one shape-defining element, a helix angle located at a predetermined diameter of the gear grinding wheel; 2. The gear grinding wheel according to claim 1, wherein the helix angle varies depending on the position in the wheel axis direction.

3. 3. The gear grinding wheel according to claim 2, wherein the predetermined diameter is a diameter of a wheel pitch circle at a predetermined position on the grinding blade in the wheel axial direction.

4. The twist angle is The grinding wheel is formed so as to have a minimum size at the intermediate portion in the grinding wheel axis direction, 3. The gear grinding wheel according to claim 2, wherein the diameters of the intermediate portion and the end portions of the wheel are gradually increased in size from the intermediate portion to the end portions of the wheel in the axial direction.

5. the torsion angle is the sum of a reference torsion angle and a correction torsion angle, the reference helix angle is the sum of the helix angle of the gear and an acute angle between the axial direction of the gear and the wheel axial direction of the gear grinding wheel, 3. The gear grinding wheel according to claim 2, wherein the correction helix angle is formed to vary depending on the position in the wheel axis direction.

6. the correcting helix angle formed on one of the blade sides of the grinding blade is formed to gradually increase from one end to the other end in the grinding wheel axis direction, 6. The gear grinding wheel according to claim 5, wherein the correcting helix angle formed on the other blade side surface of the grinding blade is formed so as to gradually decrease from one end toward the other end in the wheel axis direction.

7. the bottom surface of the grinding blade is formed so that the outer diameter dimension gradually increases from the middle portion toward the both end portions in the grinding wheel axis direction, The blade side surface of the grinding blade includes, as at least one shape defining element, a blade height that is a height from the blade bottom surface to the blade tip surface, 2. The gear grinding wheel according to claim 1, wherein the cutting edge length varies depending on the position in the wheel axis direction.

8. the blade side surface of the grinding blade includes, as at least one shape-defining element, a blade thickness located at a predetermined diameter of the gear grinding wheel; 2. The gear grinding wheel according to claim 1, wherein the cutting edge thickness varies depending on the position in the wheel axis direction.

9. The blade thickness is 9. The gear grinding wheel according to claim 8, wherein the diameter of the grinding wheel is gradually increased from the intermediate portion toward the two end portions in the axial direction of the wheel.

10. 2. The gear grinding wheel according to claim 1, wherein the width of the gear grinding wheel in the wheel axial direction is larger than the width of the gear in the axial direction.

11. A gear grinding machine comprising: The gear grinding wheel according to any one of claims 1 to 10, a control device configured to grind the tooth flank of the gear with the gear grinding wheel by rotating the gear and the gear grinding wheel synchronously while setting an axial direction of the gear and an axial direction of the gear grinding wheel to a state where a predetermined axis crossing angle is formed, and by controlling the relative positions of the gear and the gear grinding wheel.

12. a width dimension of the gear grinding wheel in the wheel axial direction is formed larger than a face width dimension of the gear, the crossed-axis angle is set to 45° or less, 12. The gear grinding device according to claim 11, wherein the control device is configured to grind the entire tooth surface of the gear by moving at least one of the gear grinding wheel and the gear so as to reduce a relative axial distance between the gear grinding wheel and the gear without moving the gear grinding wheel relatively in an axial direction of the gear.

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