Gear grinding machine and gear grinding method

Abstract

The present invention provides a gear grinding machine and a gear grinding method that can reduce noise caused by the feed rate. [Solution] The gear grinding machine comprises a workpiece rotation mechanism, a grinding wheel rotation mechanism, and a first moving mechanism. The workpiece rotation mechanism rotates a workpiece having multiple teeth on its outer surface around its central axis, the workpiece axis. The grinding wheel rotation mechanism rotates a grinding wheel having spiral grooves on its outer surface around its central axis, the grinding wheel axis. The first moving mechanism moves the grinding wheel from one end of the workpiece to the other in the tooth width direction. The gear grinding machine grinds the workpiece by synchronously rotating the workpiece and the grinding wheel while they are meshed together, and by moving the grinding wheel using the first moving mechanism. The workpiece has a first region located in the center in the tooth width direction, and a second region closer to the ends in the tooth width direction than the first region. The speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region.

Description

Technical Field

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

Background Art

[0002] Conventionally, a gear grinding machine for grinding a workpiece to be a gear is known. The gear grinding machine synchronously rotates a workpiece having teeth and a grinding wheel having a spiral groove, and brings the two into contact with each other so that the groove of the grinding wheel meshes with the teeth of the workpiece. Then, by moving the contact portion between the workpiece and the grinding wheel in the tooth width direction, the teeth of the workpiece are ground from one end to the other end in the tooth width direction.

[0003] A conventional gear grinding machine is described in, for example, Patent Document 1.

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Feed marks (tool marks) occur on the surface of the teeth ground by the gear grinding machine. The feed marks are minute irregularities formed on the tooth surface by the grinding wheel. The feed marks are periodically formed at a pitch corresponding to the moving speed of the grinding wheel. When the gears mesh, noise may occur due to these feed marks. Specifically, noise having a frequency corresponding to the pitch of the feed marks may occur separately from the noise having a frequency corresponding to the number of teeth of the gear.

[0005] Therefore, an object of the present invention is to provide a gear grinding machine and a gear grinding method capable of reducing noise caused by feed marks.

Means for Solving the Problems

[0006] The first invention is a gear grinding machine for grinding a workpiece that will become a gear, comprising: a workpiece rotation mechanism for rotating a workpiece having a plurality of teeth on its outer circumference about a workpiece axis which is its central axis; a grinding wheel rotation mechanism for rotating a grinding wheel having spiral grooves on its outer circumference about a grinding wheel axis which is its central axis; and a first moving mechanism for moving the grinding wheel from one end to the other of the workpiece in the tooth width direction parallel to the workpiece axis, wherein the workpiece rotation mechanism and the grinding wheel rotation mechanism rotate the workpiece and the grinding wheel synchronously while the first moving mechanism moves the grinding wheel, thereby grinding the workpiece, wherein the workpiece has a first region located in the center in the tooth width direction and a second region closer to the ends in the tooth width direction than the first region, and the speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region.

[0007] The second invention is a gear grinding method for grinding a workpiece that will become a gear, comprising the steps of grinding the workpiece by rotating a workpiece having a plurality of teeth on its outer circumference about its central axis, the workpiece axis, and rotating a grinding wheel having spiral grooves on its outer circumference about its central axis, the grinding wheel axis, while engaging the workpiece and the grinding wheel, and moving the grinding wheel from one end to the other of the workpiece in the tooth width direction parallel to the workpiece axis, wherein the workpiece has a first region located in the center of the tooth width direction and a second region closer to the end of the tooth width direction than the first region, and the speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region. [Effects of the Invention]

[0008] According to the first and second inventions, the pitch of the feed marks formed on the tooth surface by the grinding wheel can be made different between the first and second regions. This reduces noise caused by the feed marks when the gears mesh. Furthermore, by increasing the frequency of the noise generated from the first region, where the gears mesh relatively strongly, the noise perceived by humans can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows the configuration of a gear grinding machine. [Figure 2] Figure 2 is a flowchart showing the operation flow of a gear grinding machine. [Figure 3] Figure 3 shows the state of the workpiece and grinding wheel in step S5. [Figure 4] Figure 4 shows the state of the workpiece and grinding wheel in step S5. [Figure 5] Figure 5 shows the state of the workpiece and grinding wheel in step S5. [Figure 6] Figure 6 is a graph showing the change in the movement speed of the grinding wheel. [Figure 7] Figure 7 is a graph showing the noise analysis results when grinding a workpiece while moving the grinding wheel at a constant speed. [Figure 8] Figure 8 is a graph showing the noise analysis results when grinding a workpiece while varying the movement speed of the grinding wheel. [Modes for carrying out the invention]

[0010] <1. Configuration of a gear grinding machine> Figure 1 shows the configuration of a gear grinding machine 1 according to one embodiment. The gear grinding machine 1 is a machine tool that grinds a workpiece 9 that will become a gear.

[0011] The workpiece 9 is substantially cylindrical and has multiple teeth 91 on its outer circumferential surface. Hereinafter, the central axis of the workpiece 9 will be referred to as the "workpiece axis X1". The direction parallel to the workpiece axis X1 will be referred to as the "tooth width direction". The gear produced by grinding the workpiece 9 is, for example, a helical gear. The workpiece 9 that becomes a helical gear has spiral teeth 91 centered on the workpiece axis X1. However, the gear produced by grinding the workpiece 9 may be other types of gears, such as spur gears.

[0012] As shown in Figure 1, the gear grinding machine 1 comprises a workpiece rotation mechanism 10, a grinding wheel 20, a grinding wheel rotation mechanism 30, a moving mechanism 40, and a control unit 50. The workpiece rotation mechanism 10, the grinding wheel rotation mechanism 30, and the moving mechanism 40 are mounted on a common bed (not shown).

[0013] The workpiece rotation mechanism 10 is a mechanism that rotates the workpiece 9 around the workpiece axis X1. The workpiece rotation mechanism 10 includes a pair of clampers that hold the workpiece 9 and a motor that rotates the clampers. In this embodiment, the workpiece 9 rotates while being held in a position where the workpiece axis X1 is facing vertically. However, the orientation of the workpiece axis X1 does not necessarily have to be vertical.

[0014] The grinding wheel 20 is a tool used to grind the teeth 91 of the workpiece 9. The grinding wheel 20 is roughly cylindrical and has a helical groove 21 on its outer surface. Hereafter, the central axis of the grinding wheel 20 will be referred to as the "grinding wheel axis X2". The direction parallel to the grinding wheel axis X2 will be referred to as the "shift direction".

[0015] The grinding wheel rotation mechanism 30 is a mechanism that rotates the grinding wheel 20 around the grinding wheel shaft X2. The grinding wheel rotation mechanism 30 has a tool head that holds the grinding wheel 20 and a motor that rotates the tool head. In this embodiment, the grinding wheel 20 rotates while being held in a position where the grinding wheel shaft X2 is positioned horizontally.

[0016] The moving mechanism 40 is a mechanism for moving the grinding wheel 20 relative to the workpiece 9. The moving mechanism 40 moves the entire grinding wheel 20 and the grinding wheel rotation mechanism 30. The moving mechanism 40 includes a first moving mechanism 41, a second moving mechanism 42, and a third moving mechanism 43. The first moving mechanism 41 moves the grinding wheel 20 from one end of the workpiece 9 to the other in the tooth width direction. The second moving mechanism 42 moves the grinding wheel 20 in a shift direction relative to the workpiece 9. The third moving mechanism 43 moves the grinding wheel 20 in a direction that moves it closer to and further away from the workpiece 9.

[0017] The first moving mechanism 41, the second moving mechanism 42, and the third moving mechanism 43 are realized by, for example, a motor and a ball screw that converts the rotation of the motor into a linear motion. With these first moving mechanism 41, second moving mechanism 42, and third moving mechanism 43, the moving mechanism 40 can move the grinding wheel 20 relative to the workpiece 9 in any direction in the three-dimensional space.

[0018] Note that the moving mechanism 40 may have a fourth moving mechanism that adjusts the intersection angle between the grinding wheel axis X2 and the workpiece axis X1.

[0019] The control unit 50 is a unit that controls the operation of each part of the gear grinding machine 1. The control unit 50 is composed of, for example, a computer having a processor such as a CPU, a memory such as a RAM, and a storage unit such as a hard disk drive. A computer program for controlling the operation of the gear grinding machine 1 is stored in the storage unit.

[0020] Also, the control unit 50 is communicably connected to the workpiece rotation mechanism 10, the grinding wheel rotation mechanism 40, and the moving mechanism 40 described above. The control unit 50 controls the operation of each of these parts according to the above computer program. Thereby, the grinding process of the workpiece 9 in the gear grinding machine 1 proceeds.

[0021] <2. About the grinding method> Subsequently, a method of grinding the workpiece 9 to be a gear by the above gear grinding machine 1 will be described. FIG. 2 is a flowchart showing the flow of the operation of the gear grinding machine 1.

[0022] When grinding the workpiece 9, first, the user inputs the machining conditions to the control unit 50 (step S1). The user inputs the machining conditions to the control unit 50 via an input device such as a keyboard or a mouse. The machining conditions include, for example, the rotation speed of the workpiece 9, the rotation speed of the grinding wheel 20, and the conditions related to the movement of the grinding wheel 20 by the first moving mechanism 41. However, the machining conditions may include other conditions.

[0023] Next, the workpiece 9 is set in the gear grinding machine 1 (step S2). The workpiece 9 is held by a pair of clamps of the workpiece rotation mechanism 10. Then, the workpiece rotation mechanism 10 starts rotating the workpiece 9 around the workpiece axis X1 (step S3). Also, the grinding wheel rotation mechanism 30 starts rotating the grinding wheel 20 around the grinding wheel axis X2 (step S4). When grinding multiple workpieces 9 in succession, the rotation of the grinding wheel 20 is not stopped for each workpiece 9. In that case, when grinding the second and subsequent workpieces 9, the grinding wheel 20 that has already started rotating in step S4 is continued to rotate.

[0024] The control unit 50 controls the workpiece rotation mechanism 10 and the grinding wheel rotation mechanism 30 so that the workpiece 9 and the grinding wheel 20 rotate synchronously. Synchronous rotation means that the workpiece 9 and the grinding wheel 20 rotate in a phase that allows them to mesh with each other. The control unit 50 brings the grinding wheel 20 closer to the workpiece 9 so that the workpiece 9 and the grinding wheel 20 mesh with each other, and then uses the workpiece rotation mechanism 10 and the grinding wheel rotation mechanism 30 to rotate the workpiece 9 and the grinding wheel 20 synchronously. Then, the control unit 50 moves the grinding wheel 20 relative to the workpiece 9 using the first moving mechanism 41 (step S5).

[0025] Figures 3, 4, and 5 show the workpiece 9 and grinding wheel 20 in step S5. As shown in Figures 3, 4, and 5, the moving mechanism 40 moves the grinding wheel 20 from one end to the other of the workpiece 9 in the tooth width direction. More specifically, the moving mechanism 40 moves the grinding wheel 20 such that the contact point C between the workpiece 9 and the grinding wheel 20 moves from one end to the other of the workpiece 9 in the tooth width direction. At this time, the direction of movement of the grinding wheel 20 may be in the tooth width direction, or it may be in a direction that is slightly inclined with respect to the tooth width direction. In other words, the direction of movement of the grinding wheel 20 may be a direction that includes a component in the tooth width direction.

[0026] At the contact point C between the workpiece 9 and the grinding wheel 20, the teeth 91 of the workpiece 9 and the grooves 21 of the grinding wheel 20 slide against each other at a sliding speed corresponding to the rotational speed. This grinds the surface of the teeth 91 of the workpiece 9. As the contact point C moves in the tooth width direction, the teeth 91 of the workpiece 9 are ground from one end to the other in the tooth width direction.

[0027] At this time, tool marks are formed on the surface of the teeth 91 of the workpiece 9. Tool marks are minute irregularities formed on the surface of the teeth 91 by the grinding wheel 20. Tool marks are formed periodically at a pitch corresponding to the moving speed AF of the grinding wheel 20. If the pitch of the tool marks is constant, noise with a frequency corresponding to the pitch of the tool marks will be generated when the gears mesh. Therefore, the first moving mechanism 41 changes the moving speed AF of the grinding wheel 20 while moving the grinding wheel 20 from one end to the other of the workpiece 9. This changes the pitch of the tool marks formed on the teeth 91 of the workpiece 9.

[0028] As shown in Figures 3, 4, and 5, the workpiece 9 has a first region A1 and a pair of second regions A2. The first region A1 is the region located in the center of the tooth width direction of the workpiece 9. The second region A2 is the region closer to the ends of the workpiece 9 in the tooth width direction than the first region A1. One of the pair of second regions A2 is located between the first region A1 and one end of the workpiece 9 in the tooth width direction. The other of the pair of second regions A2 is located between the first region A1 and the other end of the workpiece 9 in the tooth width direction.

[0029] The first moving mechanism 41 sets the moving speed AF of the grinding wheel 20 in the tooth width direction slower when grinding the first region A1 than when grinding the second region A2. In this way, the pitch of the feed marks formed on the surface of the teeth 91 by the grinding wheel 20 can be made different between the first region A1 and the second region A2. This makes it possible to make the frequency of noise generated when the gears mesh different between the first region A1 and the second region A2. Therefore, it is possible to suppress the increase in gear noise at a specific frequency. As a result, noise caused by the feed marks can be reduced.

[0030] When gears mesh, the first region A1, which is the central part in the tooth width direction, meshes more strongly than the second region A2. Therefore, the noise generated from the first region A1 tends to be larger than the noise generated from the second region A2. In this embodiment, the moving speed AF of the grinding wheel 20 when grinding the first region A1 is made smaller than the moving speed AF of the grinding wheel 20 when grinding the second region A2. In this way, the pitch of the feed marks generated in the first region A1 becomes smaller than the pitch of the feed marks generated in the second region A2. Also, the height of the feed marks generated in the first region A1 becomes lower than the height of the feed marks generated in the second region A2. As a result, the frequency of the relatively large noise generated from the first region A1 becomes higher. This makes it possible to reduce the noise perceived by humans.

[0031] Figure 6 is a graph showing the change in the moving speed AF of the grinding wheel 20. The horizontal axis of Figure 6 represents the position P in the tooth width direction of the contact point C. The vertical axis of Figure 6 represents the moving speed AF of the grinding wheel 20 in the tooth width direction. In this embodiment, the first moving mechanism 41 gradually changes the moving speed AF of the grinding wheel 20 in the tooth width direction between the first region A1 and the second region A2. That is, the first moving mechanism 41 changes the moving speed of the grinding wheel 20 continuously rather than in steps. This makes it possible to smoothly change the pitch of the feed marks generated on the teeth 91 of the workpiece 9.

[0032] In particular, in the example shown in Figure 6, the first moving mechanism 41 changes the moving speed AF of the grinding wheel 20 in the tooth width direction in a sinusoidal manner. In this way, feed marks can be formed in the two second regions A2 with equivalent pitches. Furthermore, the rate of change of the feed mark pitch can be changed smoothly. Therefore, noise during gear meshing can be further reduced.

[0033] The control unit 50 calculates how to change the moving speed AF of the grinding wheel 20 based on the machining conditions entered by the user in step S1. For example, the user inputs a reference value AFo of the moving speed AF and a rate of change h of the moving speed AF to the control unit 50. The control unit 50 then calculates the maximum value AFmax and minimum value AFmin of the moving speed AF according to, for example, the following calculation formulas (1) and (2). AFmax = AFo × (1 + h) (1) AFmin = AFo × (1-h) (2)

[0034] The above rate of change h is, for example, set to a value greater than 0 and less than or equal to 0.9. In this case, the maximum value AFmax of the moving speed AF of the grinding wheel 20 in the tooth width direction is greater than 1 times the minimum value AFmin of the moving speed AF of the grinding wheel 20 in the tooth width direction, and less than or equal to 20 times. This allows for a more appropriate reduction of noise caused by the feed marks when the gears mesh.

[0035] Furthermore, it is more desirable that the maximum value AFmax of the grinding wheel 20's moving speed AF in the tooth width direction be at least 1.5 times and no more than 10 times the minimum value AFmin of the grinding wheel 20's moving speed AF in the tooth width direction. Moreover, it is even more desirable that the maximum value AFmax of the grinding wheel 20's moving speed AF in the tooth width direction be at least 2 times and no more than 5 times the minimum value AFmin of the grinding wheel 20's moving speed AF in the tooth width direction. This allows for a more appropriate reduction of noise caused by the feed teeth during gear meshing.

[0036] In this embodiment, the grinding wheel 20's movement speed AF in the tooth width direction reaches its minimum value AFmin only once while it moves from one end to the other end of the workpiece 9 in the tooth width direction. This reduces the load on the first moving mechanism 41 compared to when the grinding wheel 20's movement speed AF in the tooth width direction repeatedly increases and decreases.

[0037] Furthermore, in step S1, the user may input to the control unit 50 the travel time T of the contact point C from one end to the other end of the workpiece 9, instead of the above-mentioned reference value AFo. That is, in step S1, the user may input to the control unit 50 the travel time T and the above-mentioned rate of change h. In that case, the control unit 50 calculates the travel speed AF of the grinding wheel 20 in the tooth width direction based on the input rate of change h and travel time T. Specifically, the control unit 50 calculates the travel speed AF while changing the travel speed AF based on the input rate of change h, such that the time it takes to move the contact point C from one end to the other end of the workpiece 9 becomes the input travel time T. In this way, the travel speed AF of the grinding wheel 20 can be changed while maintaining the specified travel time T, and grinding of the workpiece 9 can be performed.

[0038] In step S5, the grinding wheel 20 may be moved in the tooth width direction by the first moving mechanism 41 while the grinding wheel 20 is moved in the shift direction by the second moving mechanism 42. This allows the portion of the grinding wheel 20 that contacts the workpiece 9 to be distributed. This extends the life of the grinding wheel 20. However, it is desirable that the moving speed SF of the grinding wheel 20 in the shift direction by the second moving mechanism 42 be sufficiently smaller than the moving speed AF of the grinding wheel 20 in the tooth width direction by the first moving mechanism 41.

[0039] As described above, the movement speed AF of the grinding wheel 20 in the tooth width direction by the first movement mechanism 41 is changed, but the movement speed SF of the grinding wheel 20 in the shift direction by the second movement mechanism 42 does not need to be changed in accordance with the movement speed AF in the tooth width direction. Rather, keeping the movement speed SF of the grinding wheel 20 in the shift direction constant reduces the load on the second movement mechanism 42.

[0040] After moving the grinding wheel 20 from one end to the other of the workpiece 9 in the tooth width direction, the moving mechanism 40 separates the grinding wheel 20 from the workpiece 9. Then, the grinding wheel rotation mechanism 30 stops the rotation of the grinding wheel 20 (step S6), and the workpiece rotation mechanism 10 stops the rotation of the workpiece 9 (step S7). After that, the workpiece 9 is removed from the gear grinding machine 1 (step S8). If the workpiece 9 is automatically replaced by a loader and the next workpiece 9 is to be ground continuously, step S7 above may be omitted and the rotation of the grinding wheel 20 may be continued.

[0041] <3. Examples> Figure 7 is a graph (comparative example) showing the results of a degree analysis of minute undulations formed on the tooth surface of a gear that was manufactured by grinding a workpiece 9 while moving the grinding wheel 20 at a constant speed AF, and measuring the shape of the tooth surface of the resulting gear. Figure 8 is a graph (example) showing the results of a degree analysis of minute undulations formed on the tooth surface of a gear that was manufactured by grinding a workpiece 9 while changing the moving speed AF of the grinding wheel 20 as shown in Figure 6, and measuring the shape of the tooth surface of the resulting gear. In the experiments in Figures 7 and 8, all conditions other than the moving speed AF of the grinding wheel 20 were kept the same.

[0042] The horizontal axis of the graphs in Figures 7 and 8 represents the order of the tooth surface waviness. The vertical axis of the graphs in Figures 7 and 8 represents the magnitude of the tooth surface waviness. These waviness order and magnitude have a high correlation with the magnitude of noise when the gears are actually meshed.

[0043] In the experiments shown in Figures 7 and 8, gears with 48 teeth were used. Therefore, it is considered normal for minute irregularities with an order that is an integer multiple of 48 to occur on the tooth surface. However, in the example in Figure 7, as shown in the area enclosed by the dashed line, irregularities with an order of 499, which is not an integer multiple of 48, occur on the tooth surface. These irregularities with an order of 499 are thought to be due to the feed marks caused by the movement speed AF of the grinding wheel 20. In contrast, in the example in Figure 8, irregularities with an order of 499 are almost absent. From these results, it was confirmed that irregularities with an order that is not an integer multiple of the number of teeth can be reduced by changing the movement speed AF of the grinding wheel 20, as shown in Figure 8. Therefore, it can be seen that noise during gear meshing can also be reduced by changing the movement speed AF of the grinding wheel 20.

[0044] <4. Variation> Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above.

[0045] In the above embodiment, in step S5, the grinding wheel 20 moved from the upper end to the lower end of the workpiece 9. However, in step S5, the grinding wheel 20 may be moved from the lower end to the upper end of the workpiece 9.

[0046] Furthermore, in the above embodiment, the moving speed AF of the grinding wheel 20 in the tooth width direction was varied in a sinusoidal manner. However, the moving speed AF of the grinding wheel 20 in the tooth width direction may be varied in other ways, such as in a quadratic curve or a step.

[0047] Furthermore, in the above embodiment, the grinding wheel 20's movement speed AF in the tooth width direction reached its minimum value AFmin only once while it moved once from one end to the other end of the workpiece 9 in the tooth width direction. However, the grinding wheel 20's movement speed AF in the tooth width direction may reach its minimum value AFmin multiple times while it moves once from one end to the other end of the workpiece 9 in the tooth width direction.

[0048] Furthermore, the elements that appear in the above embodiments and modifications may be combined as appropriate, to the extent that no contradictions arise.

[0049] <5. Summary> This technology can be configured as follows:

[0050] (1) A gear grinding machine for grinding a workpiece that will become a gear, comprising: a workpiece rotation mechanism for rotating a workpiece having a plurality of teeth on its outer circumference about a workpiece axis which is its central axis; a grinding wheel rotation mechanism for rotating a grinding wheel having spiral grooves on its outer circumference about a grinding wheel axis which is its central axis; and a first moving mechanism for moving the grinding wheel from one end to the other of the workpiece in the tooth width direction parallel to the workpiece axis, wherein the workpiece rotation mechanism and the grinding wheel rotation mechanism rotate the workpiece and the grinding wheel synchronously while the first moving mechanism moves the grinding wheel, thereby grinding the workpiece, wherein the workpiece has a first region located in the center in the tooth width direction and a second region closer to the ends in the tooth width direction than the first region, and the speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region.

[0051] (2) A gear grinding machine as described in (1), wherein the first moving mechanism gradually changes the moving speed of the grinding wheel in the tooth width direction between the first region and the second region.

[0052] (3)(2) A gear grinding machine as described in (2), wherein the first moving mechanism changes the moving speed of the grinding wheel in the tooth width direction in a sinusoidal manner.

[0053] (4) A gear grinding machine according to any one of (1) to (3), wherein the maximum value of the moving speed of the grinding wheel in the tooth width direction is greater than 1 and 20 times or less the minimum value of the moving speed of the grinding wheel in the tooth width direction.

[0054] (5)(4) gear grinding machine, wherein the first moving mechanism moves the grinding wheel once from one end to the other end of the workpiece in the tooth width direction, and the speed of the grinding wheel moving in the tooth width direction reaches the minimum value only once during this movement.

[0055] (6) A gear grinding machine according to any one of (1) to (5), further comprising a control unit that calculates the moving speed of the grinding wheel in the tooth width direction based on the rate of change of the moving speed of the grinding wheel in the tooth width direction and the moving time of the grinding wheel in the tooth width direction.

[0056] A gear grinding machine according to any one of (7)(1)) to (6), further comprising a second moving mechanism for moving the grinding wheel relative to the workpiece in a shift direction parallel to the grinding wheel axis, wherein the first moving mechanism moves the grinding wheel in the tooth width direction, and the second moving mechanism moves the grinding wheel at a constant speed in the shift direction.

[0057] (8) A gear grinding method for grinding a workpiece that will become a gear, comprising the steps of grinding the workpiece by rotating a workpiece having a plurality of teeth on its outer circumference about its central axis, the workpiece axis, and rotating a grinding wheel having spiral grooves on its outer circumference about its central axis, the grinding wheel axis, while engaging the workpiece and the grinding wheel, and moving the grinding wheel from one end to the other of the workpiece in the tooth width direction parallel to the workpiece axis, wherein the workpiece has a first region located in the center of the tooth width direction and a second region closer to the end of the tooth width direction than the first region, and the speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region.

[0058] A gear grinding method according to (9)(8), wherein the speed at which the grinding wheel moves in the tooth width direction is gradually changed between the first region and the second region.

[0059] A gear grinding method according to (10)(9), wherein the moving speed of the grinding wheel in the tooth width direction is changed in a sinusoidal manner.

[0060] A gear grinding method according to any one of (11)(8) to (10), wherein the maximum value of the moving speed of the grinding wheel in the tooth width direction is greater than 1 and 20 times or less the minimum value of the moving speed of the grinding wheel in the tooth width direction.

[0061] A gear grinding method according to (12)(11), wherein the grinding wheel moves once from one end to the other end of the workpiece in the tooth width direction, and the speed of the grinding wheel moving in the tooth width direction reaches the minimum value only once during this movement.

[0062] A gear grinding method according to any one of (13)(8) to (12), wherein the grinding wheel's moving speed in the tooth width direction is calculated based on the rate of change of the grinding wheel's moving speed in the tooth width direction and the moving time of the grinding wheel in the tooth width direction.

[0063] A gear grinding method according to any one of (14)(8) to (13), wherein in the step, the grinding wheel is moved in the tooth width direction while the grinding wheel is moved at a constant speed in a shift direction parallel to the grinding wheel axis. [Industrial applicability]

[0064] This invention can be used in gear grinding machines and gear grinding methods. [Explanation of Symbols]

[0065] 1: Gear grinding machine 9: Work 10: Workpiece rotation mechanism 20: Sharpening stone 21: Groove 30: Grinding wheel rotation mechanism 40: Movement mechanism 41: 1st movement mechanism 42:Second movement mechanism 43:Third movement mechanism 50: Control Unit 91: Teeth A1: 1st area A2:Second area AF: Movement speed in the tooth width direction AFmax: Maximum value AFmin: Minimum value AFo: Reference value C: Contact point SF: Movement speed in the shift direction T: Travel time X1: Work axis X2: Grinding wheel shaft h: rate of change

Claims

1. A gear grinding machine for grinding workpieces that will become gears, A workpiece rotation mechanism that rotates a workpiece having multiple teeth on its outer surface around its central axis, the workpiece axis, A grinding wheel rotation mechanism that rotates a grinding wheel having spiral grooves on its outer surface around its central axis, the grinding wheel axis, A first moving mechanism moves the grinding wheel from one end to the other of the workpiece in the tooth width direction parallel to the workpiece axis, Equipped with, With the workpiece and the grinding wheel engaged, the workpiece rotation mechanism and the grinding wheel rotation mechanism rotate the workpiece and the grinding wheel synchronously, and the first moving mechanism moves the grinding wheel, thereby grinding the workpiece. The aforementioned workpiece is The first region located in the central part in the tooth width direction, A second region that is closer to the end in the tooth width direction than the first region, It has, A gear grinding machine in which the speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region.

2. A gear grinding machine according to claim 1, The gear grinding machine wherein the first moving mechanism gradually changes the moving speed of the grinding wheel in the tooth width direction between the first region and the second region.

3. A gear grinding machine according to claim 2, The first moving mechanism is a gear grinding machine that changes the moving speed of the grinding wheel in the tooth width direction in a sinusoidal manner.

4. A gear grinding machine according to any one of claims 1 to 3, A gear grinding machine in which the maximum value of the moving speed of the grinding wheel in the tooth width direction is greater than 1 and less than or equal to 20 times the minimum value of the moving speed of the grinding wheel in the tooth width direction.

5. A gear grinding machine according to claim 4, A gear grinding machine in which, while the first moving mechanism moves the grinding wheel once from one end to the other end of the workpiece in the tooth width direction, the moving speed of the grinding wheel in the tooth width direction reaches the minimum value only once.

6. A gear grinding machine according to any one of claims 1 to 3, A control unit that calculates the moving speed of the grinding wheel in the tooth width direction based on the rate of change of the moving speed of the grinding wheel in the tooth width direction and the moving time of the grinding wheel in the tooth width direction. A gear grinding machine that is equipped with even more features.

7. A gear grinding machine according to any one of claims 1 to 3, A second moving mechanism moves the grinding wheel relative to the workpiece in a shift direction parallel to the grinding wheel axis. Furthermore, A gear grinding machine in which the first moving mechanism moves the grinding wheel in the tooth width direction, while the second moving mechanism moves the grinding wheel at a constant speed in the shift direction.

8. A gear grinding method for grinding a workpiece that will become a gear, The process involves grinding a workpiece by rotating a workpiece having multiple teeth on its outer surface around its central axis (workpiece axis) and a grinding wheel having spiral grooves on its outer surface around its central axis (grinding wheel axis), while engaging the workpiece and the grinding wheel, and moving the grinding wheel from one end to the other of the workpiece in the tooth width direction parallel to the workpiece axis. The aforementioned workpiece is The first region located in the central part in the tooth width direction, A second region that is closer to the end in the tooth width direction than the first region, It has, A gear grinding method wherein the speed at which the grinding wheel moves in the tooth width direction when grinding the first region is slower than the speed at which the grinding wheel moves in the tooth width direction when grinding the second region.

9. A gear grinding method according to claim 8, A gear grinding method comprising gradually changing the movement speed of the grinding wheel in the tooth width direction between the first region and the second region.

10. A gear grinding method according to claim 9, A gear grinding method comprising changing the movement speed of the grinding wheel in the tooth width direction in a sinusoidal manner.

11. A gear grinding method according to any one of claims 8 to 10, A gear grinding method wherein the maximum value of the moving speed of the grinding wheel in the tooth width direction is greater than 1 and less than or equal to 20 times the minimum value of the moving speed of the grinding wheel in the tooth width direction.

12. A gear grinding method according to claim 11, A gear grinding method in which, while the grinding wheel moves once from one end to the other end of the workpiece in the tooth width direction, the speed at which the grinding wheel moves in the tooth width direction reaches the minimum value only once.

13. A gear grinding method according to any one of claims 8 to 10, A gear grinding method for calculating the moving speed of a grinding wheel in the tooth width direction based on the rate of change of the moving speed of the grinding wheel in the tooth width direction and the moving time of the grinding wheel in the tooth width direction.

14. A gear grinding method according to any one of claims 8 to 10, A gear grinding method comprising the above step, in which the grinding wheel is moved in the tooth width direction while the grinding wheel is moved at a constant speed in a shift direction parallel to the grinding wheel axis.

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