Manufacturing method of gear

Abstract

To provide a manufacturing method of a gear by skiving processing for manufacturing a gear including various tooth forms having different pressure angles by one tool.SOLUTION: A manufacturing method of a gear cuts out a predetermined tooth form 14 by alternately repeating a cutting step in which a tool 3 is moved along a tool horizontal axis, a cutting edge distal end of the tool 3 corresponds to a position of a predetermined tooth form with respect to a workpiece 1, and the cutting edge distal end corresponding to the position of the tooth form 14 cuts the workpiece 1 along a thickness direction of the workpiece 1, and a tool horizontal axis movement step in which the tool horizontal axis is moved in a direction orthogonal to a workpiece rotation center axis 4 after the cutting step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a gear. [Background technology]

[0002] Skiving is one method of machining gears. Skiving is a method of creating gears by rotating a ring-shaped or disc-shaped workpiece (hereinafter, the workpiece to be machined into a gear will be referred to as the workpiece) while also rotating a tool with cutting edges arranged circumferentially to cut out the gear teeth. The tool rotation axis supports the workpiece and rotates at a certain cross angle with the workpiece rotation axis, so the workpiece is continuously machined as both the tool and workpiece rotate.

[0003] Skiving is a highly efficient method of cutting multiple teeth at a time. Furthermore, because the tool is held cantilevered, it is possible to cut the inner diameter of the workpiece without the tool shaft interfering with the support member.

[0004] In conventional skiving tools, the cutting edges are integrally formed with the tool, and the shape of the cutting edges is designed based on an involute curve.

[0005] Here, "tooth profile" refers to the cross-sectional shape of the tooth flank, which is the meshing surface of the gear. "Normal angle" refers to the tooth profile perpendicular to the direction of the helix angle of the tooth cut by the cutting edge. "Module" refers to the size of the gear teeth. "Pressure angle" refers to the angle between a radius line passing through any point on the tooth profile and a tangent to the tooth profile, and generally refers to the pressure angle at the reference pitch point.

[0006] Gear teeth manufactured by conventional skiving methods have a symmetrical shape. However, Patent Document 1, for example, shows a method for machining gears in which the tooth flanks and tooth tips on both sides of the teeth are asymmetrical, with the aim of improving the efficiency of force transmission between meshing gears and reducing noise.

[0007] The method disclosed in Patent Document 1 involves changing the phase of the workpiece and the tool to machine the left and right tooth flanks separately, so that the left and right tooth flanks of the gear are asymmetric with respect to the center line of the tooth bottom. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-158473 Summary of the Invention [Problem to be solved by the invention]

[0009] As mentioned above, in skiving, the cutting edge on the tool is shaped based on an involute curve, so only gears with tooth profiles based on an involute curve that have the same normal module and normal pressure angle as the cutting edge can be machined on the workpiece.

[0010] In addition to skiving, other methods for manufacturing gears include broaching, shaping, and hobbing. However, existing gear cutting methods such as broaching, shaping, hobbing, and skiving can only produce gears with tooth profiles that are basically assumed at the time of tool design.

[0011] In particular, with regard to the pressure angle, only tooth profiles having the same normal pressure angle as the cutting edge integrated into the tool can be machined.

[0012] Therefore, to machine gears with a wide variety of pressure angles, a dedicated tool is required for each tooth profile with a different pressure angle, which increases the time and cost required for preparation for machining.

[0013] In view of the above circumstances, an object of the present invention is to provide a gear manufacturing method by skiving that uses a single tool to manufacture gears having tooth profiles with different pressure angles. [Means for solving the problem]

[0014] The present invention has been made in consideration of the above-mentioned problems, and relates to a method for manufacturing a gear, in which a workpiece is rotated and a tool having cutting edges arranged in a circumferential direction is rotated around a tool rotation center axis that is inclined with respect to the workpiece rotation center axis, and the workpiece is cut with the cutting edges of the tool to cut teeth in the circumferential direction of the workpiece, a cutting step (A) in which the tool is moved along a tool horizontal axis set as the moving direction of the tool, so that the tip of the cutting edge of the tool corresponds to a predetermined position of a tooth profile with respect to the workpiece, and the tip of the cutting edge corresponding to the position of the tooth profile cuts into the workpiece along the thickness direction of the workpiece; a tool horizontal axis moving step (B) of moving the tool horizontal axis in a direction perpendicular to the workpiece rotation central axis after the cutting step (A); Repeat this process alternately to cut out the predetermined tooth shape. The present invention provides a gear manufacturing method characterized by the above-mentioned, thereby solving the above problems.

[0015] In the above invention, it is preferable that the cutting edge of the tool is formed from an insert tip.

[0016] Another invention is a method for manufacturing a gear, which comprises rotating a workpiece and rotating a tool having cutting edges arranged in a circumferential direction around a tool rotation axis inclined relative to the workpiece rotation axis, and cutting the workpiece with the cutting edges of the tool to cut teeth in the circumferential direction of the workpiece, a cutting step (A) in which the tool is moved along a tool horizontal axis set as the moving direction of the tool, so that the tip of the cutting edge of the tool corresponds to a predetermined position of a tooth profile with respect to the workpiece, and the tip of the cutting edge corresponding to the position of the tooth profile cuts into the workpiece along the thickness direction of the workpiece; a tool horizontal shaft rotational movement step (C) of rotating the tool horizontal shaft around the workpiece rotation central axis after the cutting step (A); Repeat this process alternately to cut out the predetermined tooth shape. The present invention provides a method for manufacturing a gear, which is characterized by the above-mentioned, and aims to solve the above-mentioned problems by providing the method for manufacturing a gear.

[0017] In the above invention, it is preferable that the cutting edge of the tool is formed from an insert tip. [Effects of the Invention]

[0018] According to the present invention, there is provided a method for cutting a workpiece in a thickness direction of the workpiece by moving the tool along a horizontal axis of the tool so that the tip of the cutting edge of the workpiece is positioned corresponding to a predetermined tooth profile; a tool horizontal axis moving step (B) of moving the tool horizontal axis in a direction perpendicular to the workpiece rotation central axis after the cutting step (A); This is repeated alternately to cut out a predetermined tooth shape, and the tip of the cutting edge cuts into the workpiece little by little. This allows a single tool to be used to cut out tooth profiles with different pre-set pressure angles into the workpiece, making it possible to manufacture gears with tooth profiles of any shape.

[0019] Furthermore, by forming the cutting edge from an insert tip, if the tip of the cutting edge wears out, the cutting edge can be renewed by replacing the insert tip or by changing the position of the cutting part of the insert tip. Therefore, there is no need to replace the entire tool, and the tool can be maintained inexpensively.

[0020] According to another aspect of the present invention, there is provided a method for cutting a workpiece in a thickness direction of the workpiece by moving the tool along a horizontal axis of the tool so that the tip of the cutting edge cuts the workpiece in a position corresponding to a predetermined tooth profile; a tool horizontal shaft rotational movement step (C) of rotating the tool horizontal shaft around the workpiece rotation central axis after the cutting step (A); This is repeated alternately to cut out a predetermined tooth shape, and the tip of the cutting edge cuts into the workpiece little by little. This allows a single tool to cut a predetermined tooth profile into the workpiece, making it possible to manufacture gears with tooth profiles of any shape.

[0021] In the above invention, by forming the cutting edge from the insert tip, when the tip of the cutting edge wears out, the cutting edge can be renewed by replacing the insert tip or by changing the position of the cutting part of the insert tip. Therefore, there is no need to replace the entire tool, and the tool can be maintained at low cost. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is an explanatory diagram showing a tool and a workpiece in a separated state according to the present invention. [Figure 2] 1 shows an example of a tool used in the present invention, where (a) is an explanatory diagram showing the tool as viewed from the side, (b) is an explanatory diagram showing the tool as viewed from above, (c) is an explanatory diagram showing the tool as viewed from below, and (d) is an explanatory diagram showing the tool as viewed from diagonally below. [Figure 3] The figures show an insert chip and a tool body, where (a) is an explanatory diagram showing the insert chip as seen from the side, (b) is an explanatory diagram showing the insert chip as seen from below, (c) is an explanatory diagram showing the insert chip as seen from diagonally below, and (d) is an explanatory diagram showing the tool body as seen from diagonally below. [Figure 4] FIG. 10 is an explanatory diagram showing a removal region generated on a computer. [Figure 5]FIG. 10 is an explanatory diagram showing the shape of an insert tip for generating a removal region. [Figure 6] FIG. 10 is an explanatory diagram showing a projection shape and a tooth profile generated on a computer. [Figure 7] 10A and 10B are explanatory diagrams showing an example of setting the cutting depth and horizontal axis movement amount for each tool feed. [Figure 8] FIG. 10 is an explanatory diagram showing a flow chart of the process from setting the tooth profile to machining the gear. [Figure 9] 10A and 10B are explanatory diagrams showing an example of setting the cutting depth and the horizontal axis rotation movement amount for each tool feed. [Figure 10] FIG. 10 is an explanatory diagram showing, in a flowchart, the flow of gear machining in which the tool is rotated and moved along its horizontal axis. DETAILED DESCRIPTION OF THE INVENTION

[0023] Next, the present invention will be described in detail based on the illustrated embodiments. The gear manufacturing method of the present invention involves machining gears using skiving. Figure 1 shows an overview of skiving, taking the example of an internal gear. Workpiece 1 to be machined into a gear rotates in one direction a, while tool 3, which has cutting edges 2 arranged in a circumferential direction, rotates in one direction b around tool rotation center axis 5, which is inclined at a fixed intersecting angle to workpiece rotation center axis 4.

[0024] A part of the outer periphery of the tool 3 intersects with a part of the inner periphery of the workpiece 1, and the cutting edge 2 cuts into the workpiece 1. The tool 3 moves a required amount in a direction along the workpiece rotation central axis 4. By moving the tool 3, the cutting position of the cutting edge 2 is gradually changed in the direction e (tool feed direction) along the direction of the workpiece rotation central axis 4, and the cut portion is formed so as to extend in the thickness direction of the workpiece 1.

[0025] Furthermore, every time the cutting operation by the movement of the tool 3 in the direction e along the workpiece rotation center axis 4 is completed, the tool 3 is moved in the cutting direction c (radial direction of the workpiece 1).

[0026] In this way, in the present invention, the movement of the tool 3 in the direction e along the workpiece rotation central axis 4 and the movement of the tool 3 in the cutting direction c, which is the radial direction of the workpiece, are repeated alternately to cut a tooth profile into the workpiece 1. Note that in Figure 1, the workpiece 1 and the tool 3 are shown separated vertically.

[0027] 2 shows a tool 3 used in the gear manufacturing method of the present invention. (a) is a side view, (b) is a plan view, (c) is a bottom view, and (d) is a perspective view seen from diagonally below.

[0028] As shown in Figure 2, the tool 3 has multiple cutting edges 2 arranged around the circumferential direction on the bottom of the tool 3, which is opposite the drive side mounting portion 6, and each cutting edge 2 is arranged so that a pointed triangular shape protrudes radially outward from the tool.

[0029] Furthermore, the tool 3 is configured such that the tool body 7 and the cutting edges 2 are separate members, and the tool 3 is configured by combining the tool body 7 with a plurality of members that become the cutting edges 2.

[0030] 3 shows the tool body 7 and the diamond-shaped insert tip 8 that forms the cutting edge 2, with (a) showing the insert tip 8 as seen from the side, (b) showing the insert tip 8 as seen from below, (c) showing the insert tip 8 as seen from diagonally below, and (d) showing the tool body 7 as seen from diagonally below.

[0031] As shown in FIG. 3, a tip mounting recess 9 for mounting an insert tip 8 is provided around the outer periphery of the bottom of the tool body 7 .

[0032] By placing a diamond-shaped insert chip 8 in each chip mounting recess 9 and then screwing it in place, the pointed portion 10, which is the tip of one of the cutting edges of the insert chip 8, and the straight portions 11 of the two sides continuing from the pointed portion 10 are positioned so as to protrude outward from the tool 3, thereby forming the cutting edge 2.

[0033] (Setting the target tooth profile) When machining a gear using a tool 3 on a workpiece 1 that has been prepared in advance as an annular shape, the target tooth profile of the gear is first set. The target tooth profile is set using setting information for determining the tooth profile, such as the gear's normal module, number of teeth, normal pressure angle on the pitch circle, and helix angle.

[0034] In the tool 3, the mounting angle of the insert tip 8 with respect to the tool rotation central axis 5 (that is, the mounting angle of the cutting edge 2) is known in advance.

[0035] As described above, the tool rotation center axis 5 is set at a certain inclination (axis crossing angle) with respect to the workpiece rotation center axis 4, and is set in a processing machine (not shown) that rotates the tool 3 and the workpiece 1, and is included in the rotation control of the tool 3 and the workpiece 1.

[0036] (Setting the removal area) Next, the trajectory of the cutting edge 2 of the tool 3 along the relative movement as viewed from the workpiece rotation center axis 4 is set on a computer as a virtual removal area 12 formed on the three-dimensional axes of the xw, yw, and zw axes in the workpiece coordinate system, as shown in Figure 4.

[0037] The removed region 12 does not need to be generated from the overall shape of the insert tip 8, but is formed as a pattern in which the approximate triangle representing the position of the outer edge of the cutting edge 2 has been moved. The removal area 12 shown in FIG. 4 represents the movement locus of the insert tip 8 in which the shape of the pointed portion 10 shown in FIG. 5 is made into an arc shape with a radius r.

[0038] (Generating projection shapes) Next, the virtual removal area 12 is projected on a coordinate plane on which the plane of the workpiece 1 is located, and a projected shape 13 is generated on the coordinate plane.

[0039] Figure 6 shows an example in which a virtual removal area 12 is projected on a computer in the direction of the zw axis along which the workpiece rotation center axis 4 runs, and a projected shape 13 of the virtual removal area 12 is generated on the xw-yw plane perpendicular to the zw axis. Figure 6 also shows the state in which a target gear tooth profile 14 has been generated on the xw-yw plane.

[0040] Although the projection shape 13 itself is a shape generated on a computer, it represents the tooth shape formed on the workpiece 1 after the tool 3 passes the lower end of the workpiece 1 by tool feed in the direction e along the workpiece rotation center axis 4 (the action of the member supporting the tool 3 moving downward along the workpiece rotation center axis 4).

[0041] (Creating tooth processing paths) Next, a tooth profile machining path (procedure for operating the tool) to be followed by the tool 3 is created. In order to form the tooth profile machining path, in the present invention, the direction of movement of the tool 3 (the direction in which the tool 3 advances cutting on the xw-axis-yw-axis plane) is set along the radial direction of the workpiece 1 as the tool horizontal axis 15 along which the pointed portion 10 of the cutting edge 2 advances cutting (see FIG. 7).

[0042] Furthermore, by having a machining machine (not shown) move the tool 3 in a direction perpendicular to the workpiece radial direction (xw axis direction), the tool horizontal axis 15 is moved in a direction perpendicular to the workpiece radial direction, and this can be set as the horizontal axis movement amount as described below.

[0043] (Setting the cutting depth along the tool horizontal axis) When creating a tooth profile machining path, first, the cutting depth of the pointed portion 10 of the cutting edge 2 from the inner diameter (inner peripheral surface) of the workpiece 1 is set. The cutting depth of the pointed portion 10 is set in the direction along the tool horizontal axis 15, as described above.

[0044] (Tool horizontal axis movement amount setting) Next, set the horizontal axis movement amount (yw axis direction) of the tool horizontal axis 15. The initial value of the horizontal axis movement amount is 0.

[0045] A projected shape 13 consisting of the removal area 12 and a tooth profile 14 to be formed are created on a computer, and the positional relationship between the projected shape 13 of the cusp portion 10 of the cutting edge 2 and the tooth profile 14 at the machining position based on the set cutting depth is analyzed. In other words, the computer determines whether the cusp portion 10 has reached the position of the tooth profile 14.

[0046] (When the projection shape reaches the tooth profile) If the projected shape 13 is not in contact with the workpiece 1 (tooth profile 14), a change that slightly increases the amount of horizontal axis movement is set on the computer, and the projected shape 13 is analyzed again (to determine whether the cusp portion 10 has reached the position of the tooth profile 14). If the result indicates that the projected shape 13 is in contact with the target workpiece 1, the cutting depth in the direction of the tool horizontal axis 15 and the amount of horizontal axis movement are recorded on the computer.

[0047] (When the projection shape does not reach the tooth profile) If the projected shape 13 has not reached the workpiece 1 after a change is made to increase the horizontal axis movement amount by a small amount, the computer calculates the amount of cutting depth that should be increased in the tool horizontal axis 15 to bring it into a state where it reaches the workpiece 1. Then, the computer records the cutting depth in the direction of the tool horizontal axis 15 and the horizontal axis movement amount.

[0048] (After the projection reaches the tooth profile) After it is determined that the projected shape 13 is in contact with the workpiece 1 (after the projected shape reaches the tooth profile on the computer), the amount of horizontal movement of the tool horizontal axis 15 is automatically changed by a small amount on the computer. Then, until the cusp portion 10 of the cutting edge 2 reaches the root circle (tooth bottom) of the tooth profile 14 to be formed on the workpiece 1, the cutting depth at the position of the tool horizontal axis 15 and the amount of horizontal movement of the tool horizontal axis 15 are changed and recorded on the computer so that the projected shape 13 follows the tooth profile 14.

[0049] (Setting the cutting depth and horizontal axis movement amount for each tool feed) Figure 7 shows an example in which the depth of cut and the amount of horizontal movement are set based on the arrangement of the pointed portion 10 of the cutting edge 2 and the tooth profile 14, and by changing the depth of cut and the amount of horizontal movement, the pointed portion 10 shown by the projection shape 13 on the computer comes into contact with the tooth profile 14.

[0050] 7 shows how the depth of cut and the amount of horizontal movement are set for each tool feed. From a state in which the initial positions of the cusp portion 10 and tooth profile 14 are represented on the computer, by setting the depth of cut to +1.0 mm and the amount of horizontal movement to -0.6 mm from the initial position in the first pass (one tool feed), it is determined that the cusp portion 10 shown by the projection shape 13 on the computer will come into contact with the tooth profile 14.

[0051] Furthermore, in the fifth pass (five tool feeds), the cutting depth is set to +2.5 mm and the horizontal axis movement is set to -0.41 mm relative to the positions of the cusp portion 10 and tooth profile 14 in the previous pass, which indicates that the cusp portion 10 shown by the projection shape 13 on the computer comes into contact with the tooth profile 14.

[0052] Furthermore, in the 10th PASS (10 tool feeds), by setting the cutting depth to +4.5 mm and the horizontal axis movement to -0.03 mm relative to the positions of the cusp portion 10 and tooth profile 14 in the previous PASS, it is shown that the cusp portion 10 shown by the projection shape 13 on the computer comes into contact with the tooth profile 14.

[0053] In this way, the cutting depth and the horizontal axis movement amount are changed so that the projected shape 13 comes into contact with the tooth profile 14, and the cutting depth and the horizontal axis movement amount are recorded.

[0054] The above recording of the cutting depth of the tool 3 (pointed portion 10 of cutting edge 2) and the horizontal axis movement amount of the tool horizontal axis 15 has been described as being performed on one tooth surface of the tooth profile 14, but the same is also performed on the other tooth surface of the tooth profile 14, and the cutting depth at each position of the tool horizontal axis 15 and the horizontal axis movement amount of the tool horizontal axis 15 are recorded on a computer.

[0055] (Gear processing) After the cutting depth reached to the tooth profile 14 and the horizontal axis movement amount of the tool horizontal axis 15 are recorded on the computer, the tool 3 supported by the processing machine and the workpiece 1 are rotated and the workpiece 1 is processed by the skiving method.

[0056] (flowchart) FIG. 8 is a flowchart showing the process up to the end of machining a gear, including the steps of setting the target tooth profile 14 on a computer (target tooth profile setting step 16), setting the depth of cut along the direction of the tool horizontal axis 15 (cutting depth setting step 17), and setting and recording the amount of horizontal movement of the tool horizontal axis 15 (horizontal axis movement setting step 18).

[0057] Once the cutting depth of the pointed portion 10 of the cutting edge 2 and the horizontal axis movement amount of the tool horizontal axis 15 are recorded, the stage proceeds to perform cutting on the workpiece 1 using the skiving method based on both pieces of information (stage 19 of feeding the tool and performing skiving).

[0058] The movement of the tool 3 includes the following cutting process A and tool horizontal axis movement process B, and by alternately repeating the cutting process A and the tool horizontal axis movement process B, the tooth profile 14 is cut out from the workpiece 1 and machined into a gear.

[0059] (Incision process) In the cutting process A, the tool 3 moves along the direction of the tool horizontal axis 15 so that the pointed portion 10 of the cutting edge 2 corresponds to the position of the tooth profile 14 on the workpiece 1, and the pointed portion 10 cuts into the workpiece 1 along the tooth width direction while the pointed portion 10 of the cutting edge 2 corresponds to the position of the tooth profile 14 on the workpiece 1 before cutting.

[0060] The cutting action of the pointed portion 10 in the tooth width direction is performed by feeding the tool 3 along the direction of the workpiece rotation center axis 4.

[0061] Furthermore, the movement of the pointed portion 10 to correspond to the position of the tooth profile 14 before cutting is based on the information of the cutting depth and horizontal axis movement amount recorded on the computer.

[0062] (Tool horizontal axis movement process) After one cutting process A is completed by tool feeding, the tool moves to horizontal axis movement process B. In the tool horizontal shaft moving step B, after the cutting step A, the position of the tool horizontal shaft 15 is moved in a direction perpendicular to the workpiece rotation central axis 4. The amount of horizontal movement of the tool horizontal axis 15 is very small, and is based on the information on the cutting depth and horizontal movement amount recorded in the computer.

[0063] As shown in the flowchart, when the stage 19 of tool feeding and skiving, which consists of cutting process A and tool horizontal axis movement process B, is completed in one pass, the process moves to decision stage 20, where it is determined whether to change the cutting position and continue processing.

[0064] In decision step 20, the computer that controls the skiving operation decides whether to change the cutting position and continue the process based on the information on the cutting depth and the horizontal axis movement amount recorded on the computer.

[0065] If the number of passes calculated by the computer has not been completed, the flow of control in the skiving process returns to the upstream side of step 17 where the cutting depth is set.

[0066] Also, when machining of the workpiece 1 is completed and the computer determines that there is no need to continue machining, the flow of control shifts to the end stage 21, and the production of the gear is completed.

[0067] In the above embodiment, after the cutting process A in which the pointed portion 10 of the cutting edge 2 is used to make a cut, the process moves to the tool horizontal axis moving process B in which the tool horizontal axis 15 is moved in a direction perpendicular to the tool horizontal axis 15 itself (a direction perpendicular to the workpiece rotation center axis 4), but the present invention is not limited to this embodiment.

[0068] In the present invention, after the cutting step A, the process can proceed to a tool horizontal shaft rotational movement step C in which the tool horizontal shaft 15 is rotated around the workpiece rotation center axis as shown in a flowchart described later.

[0069] First, the gear machining including the tool horizontal axis rotation movement process C will be explained below, starting with the step of creating the tooth profile machining path.

[0070] (Creating a tooth profile machining path - Tool horizontal axis rotation movement) Even when machining a gear including rotational movement of the tool horizontal axis, a tooth profile machining path is created to be followed by the tool 3. To form the tooth profile machining path, as in the above embodiment, the direction of movement of the tool 3 (the direction in which the tool 3 advances cutting on the xw-axis-yw-axis plane) is set to the radial direction of the workpiece 1 as the tool horizontal axis 15 along which the pointed portion 10 of the cutting edge 2 advances cutting.

[0071] Furthermore, by rotating the workpiece support table by a minute amount around the workpiece rotation central axis 4, the tool horizontal axis 15 is relatively moved and rotated around the workpiece rotation central axis 4.

[0072] (Setting the cutting depth along the tool horizontal axis) When creating the tooth profile machining path, the cutting depth by the pointed portion 10 of the cutting edge 2 from the inner diameter (inner peripheral surface) of the workpiece 1 is set in the same manner as in the above embodiment.

[0073] (Tool horizontal axis rotation movement amount setting) Next, set the horizontal axis rotational movement amount of the tool horizontal axis 15. The initial value of the horizontal axis rotational movement amount is 0.

[0074] The projected shape 13 and tooth profile 14 are created on a computer, and the positional relationship between the projected shape 13 of the cusp portion 10 of the cutting edge 2 and the tooth profile 14 at the machining position based on the set cutting depth is analyzed. In other words, the computer determines whether the cusp portion 10 has reached the position of the tooth profile 14.

[0075] (When the projection shape reaches the tooth profile) When the projected shape 13 is not in contact with the workpiece 1 (tooth shape 14), a change is set on the computer to slightly increase the amount of rotational movement along the horizontal axis, and the projected shape 13 is analyzed again (to determine whether the cusp portion 10 has reached the position of the tooth shape 14).

[0076] If the result is that the projected shape 13 contacts the target workpiece 1 (if the projected shape reaches the tooth profile), the cutting depth in the direction of the tool horizontal axis 15 and the horizontal axis rotation movement amount are recorded on the computer.

[0077] (When the projection shape does not reach the tooth profile) If the projected shape 13 has not reached the workpiece 1 after a change is made to increase the horizontal axis rotational movement amount by a small amount, the computer calculates the amount of cutting depth that should be increased in the tool horizontal axis 15 to bring it into a state where it reaches the workpiece 1. Then, the computer records the cutting depth in the direction of the tool horizontal axis 15 and the horizontal axis rotational movement amount.

[0078] (After the projection reaches the tooth profile) After it is determined that the projected shape 13 is in contact with the workpiece 1 (after the projected shape 13 reaches the tooth profile 14 on the computer), the amount of rotation of the tool horizontal axis 15 is automatically changed by a small amount on the computer.

[0079] Then, the cutting depth at the position of the tool horizontal axis 15 and the amount of horizontal axis rotation movement of the tool horizontal axis 15 are changed and recorded on the computer so that the projected shape 13 follows the tooth profile 14 until the pointed portion 10 of the cutting edge 2 reaches the workpiece tooth root circle (tooth bottom).

[0080] (Setting the cutting depth and horizontal axis rotation amount for each tool feed) Figure 9 shows an example in which the cutting depth and the amount of horizontal axis rotation movement are set based on the arrangement of the pointed portion 10 of the cutting edge 2 and the tooth profile 14, and by changing the cutting depth and the amount of horizontal axis rotation movement, the pointed portion 10 shown by the projection shape 13 on the computer comes into contact with the tooth profile 14.

[0081] 9 shows how the depth of cut and the horizontal axis rotational movement amount are set for each tool feed. Starting with the initial positions of the cusp portion 10 and tooth profile 14 represented on the computer, the depth of cut is set to +1.0 mm and the horizontal axis rotational movement amount is set to 1.03 degrees from the initial angular position in the first pass (one tool feed), which shows that the cusp portion 10 shown by the projected shape 13 on the computer comes into contact with the tooth profile 14.

[0082] Furthermore, in the fifth pass (five tool feeds), by setting the cutting depth to +2.5 mm and the horizontal axis rotation movement to 0.51 degrees relative to the positions of the cusp portion 10 and tooth profile 14 in the previous pass, it is shown that the cusp portion 10 shown by the projection shape 13 on the computer comes into contact with the tooth profile 14.

[0083] Furthermore, in the 10th PASS (10 tool feeds), by setting the cutting depth to +4.5 mm and the horizontal axis rotation movement to 0.03 degrees relative to the positions of the cusp portion 10 and tooth profile 14 in the previous PASS, it is shown that the cusp portion 10 shown by the projection shape 13 on the computer comes into contact with the tooth profile 14.

[0084] In this way, the cutting depth and the horizontal axis rotation amount are changed so that the projected shape 13 comes into contact with the tooth profile 14, and the cutting depth and the horizontal axis rotation amount are recorded.

[0085] The cutting depth of the tool 3 (pointed portion 10 of cutting edge 2) and the horizontal axis rotational movement amount of the tool horizontal axis 15 are recorded in the same manner for the other tooth surface of the tooth profile 14 as in the above embodiment, and the cutting depth at the position of the tool horizontal axis 15 on the tooth profile 14 and the horizontal axis rotational movement amount of the tool horizontal axis 15 are recorded on the computer.

[0086] 10 is a flowchart showing the flow of gear manufacturing when the tool horizontal axis rotational movement step C is included. Regarding this flowchart, the difference from the above-described embodiment is that it includes step 22 for setting the horizontal axis rotational movement amount after step 17 for setting the cutting depth amount.

[0087] In the stage 22 for setting the horizontal axis rotational movement amount, after each pass of cutting process A is completed, the work support table (not shown) that supports the workpiece 1 in the processing machine rotates by a small angle around the workpiece rotation center axis 4, thereby rotating the tool horizontal axis 15 relatively around the workpiece rotation center axis 4.

[0088] The amount of rotational movement of the tool horizontal shaft 15 is very small and is based on the information on the cutting depth and the amount of rotational movement of the horizontal shaft that is recorded in the computer.

[0089] In the flowchart, when step 19, which involves executing cutting process A and tool horizontal axis rotation movement process C to perform skiving processing, is completed in one pass, the process moves to decision step 20, where it is determined whether to change the cutting position and continue processing.

[0090] In decision step 20, the computer that controls the skiving operation decides whether to change the cutting position and continue the process based on the information on the cutting depth and the horizontal axis rotation movement amount recorded on the computer.

[0091] If the number of passes calculated by the computer has not been completed, the flow of control in the skiving process returns to the upstream side of step 17 where the cutting depth is set. Also, when the computer determines that there is no need to continue machining, the flow of control moves to the end stage 21, and the production of the gear is completed.

[0092] Although the above embodiment illustrates the machining of an internal gear, the present invention can also be applied to the machining of external gears. Furthermore, since the tooth profile of the gear can be preset, gears with tooth profiles having various pressure angles can be machined.

[0093] Furthermore, the insert tip 8 that forms the cutting edge 2 is not limited to a diamond-shaped insert tip. For example, the cutting edge 2 can be formed by a circular insert tip. By using a circular insert tip as the cutting edge, it is possible to machine gears with arc-shaped teeth whose tooth grooves are arcs, and it is also possible to machine gears with cycloidal teeth. [Explanation of symbols]

[0094] 1...Work 2...Cutting edge 3...Tools 4...Workpiece rotation axis 5...Tool rotation axis 6...Drive side mounting part 7...Tool body 8...Insert chip 9...Chip mounting recess 10...Pointed part 12…Removal area 13…Projected shape 14...Tooth profile 15...Tool horizontal axis 22...Step for setting the horizontal axis rotation movement amount a...Rotation direction of workpiece b...Tool rotation direction

Claims

1. A method for manufacturing a gear includes rotating a workpiece and rotating a tool having cutting edges arranged in a circumferential direction around a tool rotation center axis that is inclined relative to the workpiece rotation center axis, and cutting the workpiece with the cutting edges of the tool to cut a tooth profile in the circumferential direction of the workpiece, a cutting step (A) in which the tool is moved along a tool horizontal axis set as the moving direction of the tool, so that a cutting edge of the tool corresponds to a predetermined tooth profile position with respect to the workpiece, and the cutting edge corresponding to the tooth profile position cuts into the workpiece along the thickness direction of the workpiece; a tool horizontal axis moving step (B) of moving the tool horizontal axis in a direction perpendicular to the workpiece rotation central axis after the cutting step (A); Repeat this process alternately to cut out the predetermined tooth shape. A gear manufacturing method characterized by:

2. 2. The method for manufacturing a gear according to claim 1, wherein the cutting edge of the tool is formed from an insert tip.

3. A method for manufacturing a gear includes rotating a workpiece and rotating a tool having cutting edges arranged in a circumferential direction around a tool rotation center axis that is inclined relative to the workpiece rotation center axis, and cutting the workpiece with the cutting edges of the tool to cut teeth in the circumferential direction of the workpiece, a cutting step (A) in which the tool is moved along a tool horizontal axis set as the moving direction of the tool, so that a cutting edge of the tool corresponds to a predetermined tooth profile position with respect to the workpiece, and the cutting edge corresponding to the tooth profile position cuts into the workpiece along the thickness direction of the workpiece; a tool horizontal shaft rotational movement step (C) of rotating the tool horizontal shaft around the workpiece rotation central axis after the cutting step (A); Repeat this process alternately to cut out the predetermined tooth shape. A gear manufacturing method characterized by:

4. The method for manufacturing a gear according to claim 3, wherein the cutting edge of the tool is formed from an insert tip.

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