Tooth surface polishing device

Abstract

To provide a tooth surface polishing device which can properly adjust a pressure acting on a tooth surface while inhibiting increase in size of the device.SOLUTION: A tooth surface polishing device 1 includes a gear to be processed (a processed gear) 2 which is subject to processing and a screw-shaped tool 3 having a thread which engages with the processed gear 2 to polish a tooth surface of the processed gear 2. The processed gear 2 and the screw-shaped tool 3 are arranged so as to engage with each other in a state that their axes do not intersect and are not parallel to each other. The tooth surface polishing device 1 includes: driving means which rotates the screw-shaped tool 3; reaction force means which rotates or brakes the processed gear 2; and propelling means which moves or presses the screw-shaped tool 3 in a direction in which teeth of the processed gear 2 and the thread of the screw-shaped tool 3 contact with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gear tooth surface polishing device for reducing the surface roughness of gear tooth surfaces. [Background technology]

[0002] Patent Document 1 describes a lapping device that polishes the tooth flanks of a workpiece gear by rotating a wrap gear meshed with the workpiece gear. In this lapping device, the workpiece gear and the wrap gear are arranged to mesh with each other on non-intersecting axes, and the workpiece gear and the wrap gear are moved relative to each other in a direction perpendicular to the rotational axis of the workpiece gear. Patent Document 1 also describes a wrap gear consisting of a pair of gears, a drive wrap gear and a brake wrap gear, that mesh with the workpiece gear. By controlling the rotation speed of the brake wrap gear to be lower than that of the drive wrap gear, both the leading and trailing sides of the workpiece gear in the rotational direction are simultaneously lapped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-215821 Summary of the Invention [Problem to be solved by the invention]

[0004] The lapping device described in Patent Document 1 is configured so that a drive wrap gear and a brake wrap gear mesh with the gear to be processed, and by controlling the rotation speeds of these wrap gears to be different, the brake wrap gear essentially bears the reaction torque, and a predetermined pressing force acts on the tooth surface of the gear to perform the lapping. In other words, it is necessary to have a wrap gear that presses the tooth surface of the gear to be processed, and a wrap gear that bears the reaction torque, which can result in the lapping device becoming larger.

[0005] The present invention has been made with a focus on the above-mentioned technical problems, and aims to provide a tooth surface polishing device that can appropriately adjust the pressure acting on the tooth surface while preventing the device from becoming too large. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a tooth surface polishing device comprising a workpiece gear to be processed and a threaded tool having a thread that meshes with the workpiece gear to polish the tooth surface of the workpiece gear, wherein the workpiece gear and the threaded tool are arranged to mesh with each other on non-intersecting axes, and the device is characterized by comprising a drive means for rotating the threaded tool, a reaction force means for rotating or braking the workpiece gear, and a propulsion means for moving or pressing the threaded tool in a direction in which the teeth of the workpiece gear and the threads of the threaded tool come into contact. [Effects of the Invention]

[0007] The tooth surface polishing device of the present invention drives the threaded tool using a rotating means and drives or brakes the workpiece gear using a reaction force means. Therefore, surface pressure is generated on the contact surface between the teeth of the workpiece gear and the threads of the threaded tool. The workpiece gear and the threaded tool are engaged with each other via a non-intersecting axis. Therefore, as the engagement between the workpiece gear and the threaded tool progresses, the engagement surfaces between the workpiece gear and the threaded tool change while sliding in the direction of the tooth trace of the workpiece gear. As a result, the tooth surface of the workpiece gear can be polished by the threaded tool due to the frictional force resulting from the surface pressure acting on the tooth surface of the workpiece gear and the sliding on that tooth surface.

[0008] Furthermore, by moving or pressing the threaded tool in a direction that brings the teeth of the workpiece gear into contact with the threads of the threaded tool, it is possible to move or press the threaded tool so that the teeth of the workpiece gear and the threads of the threaded tool remain in contact with each other, even when the threaded tool is made of a material with relatively low rigidity. This prevents tooth strike, which occurs when the teeth of the workpiece gear and the threads of the threaded tool repeatedly come into contact and separate within backlash due to elastic deformation of the threaded tool, and prevents fluctuations in the contact pressure between the teeth of the workpiece gear and the threaded tool. As a result, it is possible to appropriately adjust the pressure acting on the meshing surfaces of the workpiece gear and the threaded tool, thereby enabling the tooth flanks of the workpiece gear to be polished evenly. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a tooth surface polishing device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of specific embodiments of the present invention and are not intended to limit the present invention.

[0011] An example of a tooth surface polishing apparatus according to an embodiment of the present invention is shown in Figure 1. The tooth surface polishing apparatus 1 shown in Figure 1 is configured to polish the tooth surface of a gear 2 to be processed by meshing a threaded tool 3 with the gear 2 to be processed and rotating the tool.

[0012] 1 is composed of a screw gear with a helical thread formed on a cylindrical base. This threaded tool 3 grinds the tooth surface of the workpiece gear 2 by contacting it with the workpiece gear 2, and therefore may be composed of a grinding stone made of an elastic material, or may be composed of an elastic material that holds free abrasive grains on the surface that comes into contact with the workpiece gear 2.

[0013] A rotating shaft (not shown) is connected to the threaded tool 3 so as to rotate integrally therewith. Specifically, for example, the threaded tool 3 is formed in a cylindrical shape, and the rotating shaft is engaged with its hollow portion by a spline or the like. A drive actuator (not shown), such as a motor, for rotating the threaded tool 3 is connected to the rotating shaft. Therefore, by driving the drive actuator, the rotating shaft and the threaded tool 3 rotate at a predetermined rotational speed, or a torque for rotating the threaded tool 3 is applied. This drive actuator corresponds to the "driving means" in the embodiments of the present invention.

[0014] The workpiece gear 2 shown in Fig. 1 is an external gear. This workpiece gear 2 may be a spur gear whose teeth are straight and parallel to the rotation axis L1 of the workpiece gear, or a helical gear whose teeth are inclined relative to the rotation axis L1.

[0015] This workpiece gear 2 meshes with the threaded tool 3 and rotates when torque is applied from the threaded tool 3. In order to polish the tooth surface of the workpiece gear 2, in other words, it is configured so that the surface pressure acting on the tooth surface of the workpiece gear 2 is a predetermined surface pressure.

[0016] A rotating shaft (not shown) is connected to the workpiece gear 2 so that they rotate integrally. Specifically, a through hole is formed along the rotational center axis L1 of the workpiece gear 2, and the rotating shaft is engaged with the through hole via a spline or the like. The rotating shaft is provided with a reaction force device, such as a motor (not shown) that rotates the workpiece gear 2 at a predetermined rotational speed or a brake actuator that brakes the workpiece gear 2. That is, the reaction force device is configured to rotate the workpiece gear 2 at a rotational speed slower than the rotational speed of the workpiece gear 2 calculated by multiplying the rotational speed of the threaded tool 3 by the gear ratio of the workpiece gear 2 and the threaded tool 3, or to brake the workpiece gear 2, so that the tooth flank on the rear side in the direction of tooth advancement of the workpiece gear 2 comes into contact with the thread of the threaded tool 3, and the contact surface pressure becomes a predetermined surface pressure. A torque sensor is provided on the rotating shaft to which the workpiece gear 2 is connected for detecting the torque acting on the workpiece gear 2, specifically, the torque received by the threaded tool 3 from the workpiece gear 2.

[0017] Furthermore, to generate slippage for polishing the tooth flanks of the workpiece gear 2, the workpiece gear 2 and the threaded tool 3 are meshed with each other via non-intersecting axes. That is, the workpiece gear 2 and the threaded tool 3 are positioned and meshed with each other so that the central rotation axis L1 of the workpiece gear 2 and the central rotation axis L2 of the threaded tool 3 do not intersect or run parallel to each other. Therefore, when the workpiece gear 2 and the threaded tool 3 mesh and rotate, their meshing surfaces move while sliding in the tooth trace direction of the workpiece gear 2.

[0018] In the tooth surface polishing device 1 configured as described above, by operating the drive actuator to rotate the threaded tool 3, the threads of the threaded tool 3 come into contact with the tooth surface facing backward in the rotational direction of the workpiece gear 2, causing the workpiece gear 2 to rotate together with the threaded tool 3. At this time, the workpiece gear 2 is rotated at a low speed or braked by the reaction means, generating surface pressure on the contact surface between the workpiece gear 2 and the threaded tool 3.

[0019] Furthermore, since the workpiece gear 2 and the threaded tool 3 are meshed with each other through non-coincident axes, as the meshing between the workpiece gear 2 and the threaded tool 3 progresses, in other words, as the rotation angle of the workpiece gear 2 increases, the meshing surfaces between the workpiece gear 2 and the threaded tool 3 change while sliding in the tooth trace direction of the workpiece gear 2.

[0020] Therefore, the tooth flank of the gear 2 to be machined can be polished by the threaded tool 3 due to the frictional force resulting from the surface pressure acting on the tooth flank of the gear 2 to be machined and the sliding on the tooth flank.

[0021] Furthermore, since the threaded tool 3 is used to grind the workpiece gear 2, it is made of an elastic material as described above and has lower rigidity than the workpiece gear 2. Therefore, when grinding the workpiece gear 2, the load (reaction force) acting from the workpiece gear 2 to the threaded tool 3 causes deflection in the threads (teeth) of the threaded tool 3. Furthermore, as the rotation angle of the workpiece gear 2 progresses, the meshing position between the workpiece gear 2 and the threaded tool 3 changes in the tooth depth direction, causing a change in the meshing state.

[0022] Therefore, the load (surface pressure) acting on the meshing surfaces of the workpiece gear 2 and the threaded tool 3 changes as the meshing state between the workpiece gear 2 and the threaded tool 3 changes. When the load acting on the meshing surfaces of the threaded tool 3 changes in this way, the amount of deflection (amount of elastic deformation) of the threaded tool 3 changes and the elastic force changes, causing the load acting on the workpiece gear 2 to change. In other words, the torque acting on the rotating shaft connected to the workpiece gear 2 not only changes with the change in the meshing state, but also with the change in the elastic force of the threaded tool 3.

[0023] Therefore, the above-mentioned tooth surface polishing device 1 is provided with a propulsion means for moving the threaded tool 3 in the direction of the rotational center axis L2 of the threaded tool 3 in order to maintain contact between the tooth surface of the gear 2 to be processed and the thread of the threaded tool 3, and to maintain that contact pressure (surface pressure). This propulsion means can be configured, for example, by an electromagnetic actuator that moves the threaded tool 3 back and forth using electromagnetic force, or a hydraulic actuator that moves the threaded tool 3 to one side using supplied hydraulic pressure.

[0024] The propulsion means is configured to control the movement amount of the threaded tool 3 or the pressing force of the threaded tool 3 in accordance with the torque acting on the workpiece gear 2. Specifically, the torque acting on the workpiece gear 2 is detected by the torque sensor described above, and the propulsion means is controlled so that the torque detected by the torque sensor becomes a predetermined torque. That is, if the torque acting on the workpiece gear 2 is higher than the predetermined torque, the movement amount or pressing force of the threaded tool 3 by the propulsion means is reduced, and if the torque acting on the workpiece gear 2 is lower than the predetermined torque, the movement amount or pressing force of the threaded tool 3 by the propulsion means is increased. In addition to the propulsion means, a torsion spring or the like may be provided on the rotation shaft of the workpiece gear 2 to generate an elastic force in a direction that increases the surface pressure.

[0025] Furthermore, in order for the workpiece gear 2 and the threaded tool 3 to rotate smoothly, a predetermined backlash is provided between the teeth of the workpiece gear 2 and the threads of the threaded tool 3. Specifically, a distance adjustment mechanism is provided to adjust the distance between the rotation center of the workpiece gear 2 and the rotation center axis L2 of the threaded tool 3.

[0026] In the tooth surface polishing device 1 configured as described above, first, the workpiece gear 2 is connected to a rotating shaft, and similarly, the threaded tool is connected to the rotating shaft. Next, the distance between the center of rotation of the workpiece gear 2 and the central axis L2 of the threaded tool 3 is adjusted using the distance adjustment mechanism so that a predetermined backlash is provided between the teeth of the workpiece gear 2 and the threads of the threaded tool 3, thereby meshing the workpiece gear 2 and the threaded tool 3 with their offset axes. The drive actuator then rotates the threaded tool 3, and the reaction force means rotates the workpiece gear 2 at a predetermined rotational speed or brakes the workpiece gear 2. The propulsion means controls the movement amount and pressing force of the threaded tool 3 based on the torque value detected by the torque sensor. That is, the propulsion means is feedback-controlled using the deviation between the actual surface pressure acting on the tooth surface of the workpiece gear 2, based on the torque acting on the workpiece gear 2, and the target surface pressure acting on the tooth surface of the workpiece gear 2, as a feedback value.

[0027] The tooth surface polishing device 1 configured as described above drives the threaded tool 3 using the drive actuator and drives or brakes the workpiece gear 3 using the reaction force means. Therefore, surface pressure is generated on the contact surface between the teeth of the workpiece gear 2 and the threads of the threaded tool 3. The workpiece gear 2 and the threaded tool 3 are meshed with each other via non-intersecting axes. Therefore, as the meshing between the workpiece gear 2 and the threaded tool 3 progresses, the meshing surfaces between the workpiece gear 2 and the threaded tool 3 change while sliding in the tooth trace direction of the workpiece gear 2. As a result, the tooth surface of the workpiece gear 2 can be polished by the threaded tool 3 due to the frictional force resulting from the surface pressure acting on the tooth surface of the workpiece gear 2 and the sliding on that tooth surface.

[0028] Furthermore, by moving or pressing the threaded tool 3 in the direction of the rotation axis of the threaded tool 3 in a direction in which the teeth of the workpiece gear 2 come into contact with the threads of the threaded tool 3, it is possible to move or press the threaded tool 3 so that the teeth of the workpiece gear 2 and the threads of the threaded tool 3 maintain contact with each other, even when the threaded tool 3 is made of a material with relatively low rigidity. This makes it possible to prevent tooth rattle caused by repeated contact and separation between the teeth of the workpiece gear 2 and the threads of the threaded tool 3 within backlash due to elastic deformation of the threaded tool 3, as well as fluctuations in the contact pressure between the teeth of the workpiece gear 2 and the threads of the threaded tool 3. As a result, it is possible to appropriately adjust the pressure acting on the meshing surfaces of the workpiece gear 2 and the threaded tool 3, and to evenly polish the tooth flanks of the workpiece gear 2.

[0029] It should be noted that the threaded tool 3 in the embodiment of the present invention is not limited to one that holds a grinding stone or loose abrasive grains, but may, for example, be made of an elastic material and configured to supply loose abrasive grains to the meshing surface between the threaded tool 3 and the workpiece gear 2.

[0030] The distance adjustment mechanism may maintain a constant distance between the rotational axis L1 of the workpiece gear 2 and the rotational axis L2 of the threaded tool 3 during the process of grinding the tooth surface of the workpiece gear 2, or may change that distance as needed. Furthermore, the propelling means need only be able to maintain contact between the workpiece gear 2 and the threaded tool 3 and maintain the contact pressure, and is not limited to the propelling means that moves in the direction of the rotational axis L2 of the threaded tool 3 as described above, but may also be configured to move in a direction parallel to the rotational axis L1 of the workpiece gear 2, or in a direction inclined relative to the rotational axis L1.

[0031] Furthermore, the thread of the threaded tool 3 may be a single-start thread, or a multiple-start thread having two or more start threads. The driving means is not limited to one that moves or presses the threaded tool 3 in one direction, but may be configured to reciprocate the threaded tool 3. By reciprocating the threaded tool 3 in this way, both sides of the workpiece gear 2 can be polished. When the threaded tool 3 is configured to move or press in one direction, the rotational direction of the workpiece gear 2 and the threaded tool 3 may be configured to alternate between positive and negative (clockwise and counterclockwise).

[0032] Furthermore, the threaded tool 3 may be long in the axial direction to increase the number of teeth machined in one stroke, or short in the axial direction to increase the number of strokes. When grinding the tooth surface of the workpiece gear 2 by repeatedly moving the threaded tool 3 toward one side in the axial direction, the distance between the rotation center axis L1 of the workpiece gear 2 and the rotation center axis L2 of the threaded tool 3 may be changed by a distance adjustment mechanism when returning the stroke.

[0033] Furthermore, the above-mentioned propulsion means is configured to control the movement amount and pressing force of the threaded tool 3 based on the detection value of the torque sensor, but it may also be configured to control the movement amount and pressing force of the threaded tool 3 by feedforward control using the rotation angles of the workpiece gear 2 and the threaded tool 3 as parameters, for example. [Explanation of symbols]

[0034] 1 Tooth surface polishing device 2 Gear to be machined 3. Threaded tools L1 Rotational axis L2 Rotation center axis

Claims

[Claim 1] A tooth surface polishing device including a gear to be processed and a threaded tool having a screw thread that meshes with the gear to be processed and polishes the tooth surface of the gear to be processed, the gear to be machined and the threaded tool are arranged to mesh with each other at offset axes, a driving means for rotating the threaded tool; a reaction force means for rotating or braking the gear to be machined; a propulsion means for moving or pushing the threaded tool in a direction in which the teeth of the gear to be machined and the threads of the threaded tool come into contact with each other; Equipped with A tooth surface polishing device characterized by:

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