Machining method for gear component, program therefor, and machining device

Abstract

The present invention is a machining method for a gear component capable of accurately machining a non-gear cutting part, a program therefor, and a machining device. The machining method according to the present invention includes: causing a workpiece spindle to grip a workpiece so that the axis of the workpiece is along a rotary machining axis on one end side of the workpiece that is columnar and has a gear cutting part which is cut on a part of the circumference along the axial direction; measuring the gear cutting part to calculate a deviation of the central axis of the gear cutting part from the rotary machining axis; and performing an eccentric machining from the other end side to the rotary machining axis on the basis of the deviation. The program causes a workpiece spindle to grip a workpiece so that the axis of the workpiece is along a rotary machining axis on one end side of the workpiece that is columnar and has a gear cutting part which is cut on a part of the circumference along the axial direction, causes the gear cutting part to be measured; calculates a deviation of the central axis of the gear cutting part from the rotary machining axis from the measured measurement value; and causes an eccentric machining to be performed from the other end side of the workpiece to the rotary machining axis on the basis of the calculated deviation. The machining device includes a first workpiece spindle, a tool holding device, a moving device, and a control device for controlling the driving thereof, and follows the machining program.

Description

Gear component processing method, program and processing device

[0001] The present invention relates to a gear component machining method, a program therefor, and a machining device, and more particularly to a gear component machining method, a program therefor, and a machining device therefor that machine non-tooth cutting portions.

[0002] In a known gear cutting process, a rotating hob is pressed against a rotating workpiece while rotating to cut a gear. If the rotation axis of the rotary table does not coincide with the axis of the workpiece, the gear teeth will be machined eccentrically.

[0003] For example, Patent Document 1 discloses a machining method for gear cutting using a hobbing machine, in which the rotation phase of the rotary table and the cutting depth of the hob cutter are corrected so as to cancel out the eccentricity between the rotation axis of the rotary table and the axis of the workpiece. This method is said to enable high-precision gear machining even for workpieces that are eccentrically mounted.

[0004] International Publication No. 2011 / 129008

[0005] By using a multi-tasking machine, it is possible to attach a hob cutter to perform gear cutting on the circumferential surface of a workpiece, etc., to form a gear cutting portion, and then change tools to continue cutting other portions. In this case, if the workpiece is temporarily removed from the workpiece spindle after gear cutting and then reattached to perform rotary cutting, the rotation axis of the workpiece spindle and the central axis of the gear cutting portion of the attached workpiece will not coincide, making it impossible to perform accurate rotary cutting. The same problem occurs when the gear-cut part is attached to the processing machine and further rotary cutting is attempted.

[0006] An object of the present invention is to provide a gear component machining method, a program therefor, and a machining device that precisely machine portions other than the gear cutting portion.

[0007] The method for machining gear parts according to the present invention involves gripping a cylindrical workpiece having a gear cutting portion machined on a portion of the circumference along the axis with a workpiece spindle at one end so that the axis is aligned with the rotary machining axis, measuring the gear cutting portion and calculating the deviation of the central axis of the gear cutting portion from the rotary machining axis, and then performing eccentric machining from the other end side with respect to the rotary machining axis based on this deviation.

[0008] In addition, the machining program according to the present invention measures the gear cutting portion by gripping the workpiece with the work spindle at one end side of a cylindrical workpiece having a gear cutting portion machined on a portion of the circumference along the axis so that the axis is aligned with the rotary machining axis, calculates the deviation of the central axis of the gear cutting portion from the rotary machining axis from the measured value, and performs eccentric machining from the other end side with respect to the rotary machining axis based on the calculated deviation.

[0009] Furthermore, the machining apparatus according to the present invention includes a first work spindle that rotatably grips a workpiece, a tool holding device that holds a measuring instrument or a tool, a moving device that can move the first work spindle and the tool holding device relatively, and a control device that controls the driving of the first work spindle, the tool holding device, and the moving device, and in accordance with a machining program, the first work spindle holds the workpiece at one end of a columnar workpiece having a gear cutting portion machined on a portion of the circumference along the axis so that the axis is along the rotary machining axis, the measuring instrument held by the tool holding device measures the gear cutting portion, calculates the deviation of the central axis of the gear cutting portion from the rotary machining axis from the measured value, and, based on the calculated deviation, performs eccentric machining of the workpiece from the other end side with respect to the rotary machining axis using a tool held by the tool holding device.

[0010] According to the above invention, it is possible to precisely machine the portions other than the gear cutting portion.

[0011] FIG. 1 is a perspective view (partially a block diagram) of a main part of a machining device in one embodiment according to the present invention; FIG. 2 is a side sectional view of a workpiece in one embodiment according to the present invention; FIG. 3 is a flow diagram showing a machining method in one embodiment according to the present invention; FIG. 4 is a side view of a columnar material attached to a first work spindle; FIG. 5 is a side sectional view of a columnar material to be turned and drilled; FIG. 6 is a side sectional view of a columnar material (workpiece) to be gear cut; FIG. 7 is a side sectional view of a workpiece reattached to the first work spindle; FIG. 8 is a side sectional view of a workpiece to be subjected to tooth pitch measurement; FIG. 9 is a side sectional view of a workpiece to be eccentrically machined; FIG. 10 is a front view of a workpiece to explain the deviation of the central axis in another embodiment; FIG. 11 is a front view of a workpiece to explain the correction of the deviation of the central axis in another embodiment.

[0012] Hereinafter, a gear component machining method, a program therefor, and a machining apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 5C.

[0013] First, a processing device used in the gear component processing method will be described.

[0014] As shown in FIG. 1 , the machining device 1 is a numerically controlled machine tool that operates according to an input program. Furthermore, it is preferably a multi-tasking machine with an automatic tool change function. Here, a machine equipped with spindle units on each side of a base 2 as viewed from the drawing (in the description of FIG. 1 , the left, right, front, etc. are referred to as the view from the drawing; the same applies hereinafter in the descriptions of the respective drawings) is used as an example. Of the left and right spindle units, the left one is a first spindle unit 10 to which a workpiece W is attached, and the right one is a second spindle unit 20. The left first spindle unit 10 includes a workpiece headstock 11 and a first workpiece spindle 12. The first workpiece spindle 12 grips the workpiece W and supports it rotatably around the rotary machining axis C of the first workpiece spindle 12. The right second spindle unit 20 includes a workpiece headstock 21 and a second workpiece spindle 22. Similarly, the right second spindle unit 20 can grip the workpiece W and support it rotatably around the rotary machining axis C' of the second workpiece spindle, and is used as needed. The first work spindle 12 and the second work spindle 22 are arranged facing each other, and are provided with a spindle movement mechanism (not shown) that changes the relative distance between them so that the workpieces can be transferred between them. Therefore, the rotary machining axis C and the rotary machining axis C' are arranged to coincide with each other, and movement by the spindle movement mechanism is along the rotary machining axis C.

[0015] The processing device 1 is further provided with a column unit 31 that is movable horizontally left and right on the base 2. The column unit 31 is attached to the base 2 so as to be movable in parallel left and right along the Z axis, and its position in the Z axis direction is adjusted by a combination of a Z axis servo motor 31a and a Z axis ball screw 31b. A swivel shaft 33 is attached to the front side of the column unit 31 via a combination of an X axis servo motor 32a and an X axis ball screw 32b. This allows the swivel shaft 33 to move in parallel in both the X axis and Z axis directions. The swivel shaft 33 is further rotatable about a rotation axis extending in the Y axis direction, and a tool holding device 33a provided at the tip portion is rotatable about an axis perpendicular to the Y axis. In other words, the tool holding device 33a can be moved relative to the first work spindle 12 and the second work spindle 22 by a moving device 30 consisting of a series of drive mechanisms including a column unit 31, a Z-axis servo motor 31a, a Z-axis ball screw 31b, a swivel shaft 33, an X-axis servo motor 32a, and an X-axis ball screw 32b.

[0016] A tool or the like 34 is attached to the tool holding device 33a. Examples of the tool or the like 34 include measuring instruments such as a touch probe 34a shown here and tools such as cutting tools. The touch probe 34a can be used to measure the dimensions of the workpiece W by bringing its tip into contact with the surface of the workpiece W to obtain coordinates of the contact position relative to the base 2. The touch probe 34a can also be replaced with a hob cutter (described later) to form a gear cutting portion on the workpiece W. In other words, the tool holding device 33a can be used as a cutting device that cuts the workpiece W or a measuring device that measures the workpiece W, depending on the attached tool or the like 34. An automatic tool changer 45 is provided on the right side of the base 2, and the tool holding device 33a can be moved close to the tool holding device 33a to automatically change measuring instruments or cutting tools and hold them in the tool holding device 33a.

[0017] The machining apparatus 1 further includes a control device 40 that performs numerical control and can control the drive of the first spindle unit 10, the second spindle unit 20, the moving device 30, the automatic tool changer 45, and the like. The control device 40 includes an input interface (not shown) operated by an operator and is connected to a calculation device 41. The calculation device 41 includes at least a memory unit 42 that stores a gear component machining program and a calculation unit 43. The calculation device 41 then sends a signal to the control device 40 to control the operation of the machining apparatus 1 according to the program read from the memory unit 42, thereby operating the machining apparatus 1 to perform a gear component machining method described below. The calculation unit 43 can acquire measurement values, such as coordinate data of the workpiece W measured by the touch probe 34a, from the control device 40 and calculate the deviation between the center axis A and the rotary machining axis C described below. The calculation device 41 may be built into the control device 40.

[0018] Next, a method for machining a gear component using the machining device 1 will be described.

[0019] As shown in FIG. 2 , the gear component to be obtained by machining the workpiece W is a stepped columnar component having a gear cutting portion formed on a portion of the circumference along the axis A′. After machining the gear cutting portion, one end along the axis A′ is grasped and machined from the other end. Here, a gear component having a stepped cylindrical shape is illustrated, with a gear cutting portion 51 having gear teeth 51a formed on the outer periphery at the center in the left-right direction of the page, and approximately cylindrical shaft portions 52 and 53 on both sides. Furthermore, each of the shaft portions 52 and 53 has a hole 52a and 53a, respectively, which is a bottomed hole cut from the end face toward the center. The hole 52a and 53a are, for example, a bearing journal.

[0020] Furthermore, a processing procedure including a gear component processing method will be described with reference to FIGS. 4A to 5C along with FIG.

[0021] First, a columnar material W' for obtaining the workpiece W is attached to the first workpiece spindle 12 (S1).

[0022] 4A, the columnar material W' has a gear-cutting circumferential portion 51' having a large diameter and a substantially circular disk shape in the center, and cylindrical shaft-like portions 52 and 53 on either side of the circumferential portion 51'. The outer peripheries and side surfaces of the stepped portions of the gear-cutting circumferential portion 51' and the shaft-like portions 52 and 53 have been roughly machined. The first work spindle 12 grips the vicinity of the end of the shaft-like portion 52 and cantilevers the columnar material W'. The central axis A will be described later.

[0023] Next, referring also to FIG. 4B , the gear-cutting circumferential portion 51′ of the columnar blank W′ is turned, and the shaft-shaped portion 53 on the end of the columnar blank W′, which is not held by the workpiece W, is turned and then drilled (S2). The turning of the gear-cutting circumferential portion 51′ is a process for forming a blank for gear cutting, which will be described later, by turning the outer circumferential surface and the side of the stepped portion. The turning of the shaft-shaped portion 53 is a finishing process for the shaft-shaped portion 53 of a gear component. These turning processes are performed using a turning tool 34b as the tool 34 held by the tool holding device 33a (see FIG. 1) of the moving device 30. Meanwhile, the drilling of the shaft-shaped portion 53 is a process for forming the hole 53a. In such drilling, for example, a pilot hole is formed by cutting using a rotary tool 34c such as a U-drill held by a tool holding device 33a, and then the hole is expanded using an end mill (not shown), or the inner surface is turned using a turning tool.

[0024] Next, referring also to FIG. 4C , the outer periphery of the gear-cutting circumferential portion 51′ is subjected to gear cutting to form a tooth portion 51a, thereby obtaining a workpiece W from the columnar blank W′ (S3). Here, a hob cutter 34d is attached to the tool holding device 33a (see FIG. 1) of the moving device 30, and the columnar blank W′ is rotated around the rotary machining axis C (see FIG. 1) of the first workpiece spindle 12 in synchronization with the rotation of the hob cutter 34d, thereby performing gear cutting. Furthermore, the tooth portion 51a is deburred, and the phase of the formed tooth portion 51a is measured. A touch probe 34a attached to the tool holding device 33a can be used for such measurements. An automatic tool changer 45 is used to replace measuring instruments such as the touch probe 34a and cutting tools attached to the tool holding device 33a.

[0025] Up to this point, the columnar material W' has been machined while being fixed to the first work spindle 12. In other words, the turning and gear cutting processes have been performed while the columnar material W' is rotated around the rotational processing axis C of the first work spindle 12. Therefore, the central axis A of the gear-cutting portion 51 and shaft portion 53 coincides with the rotational processing axis C. In other words, up to this point, the columnar material W' has been machined while being rotated around the central axis A.

[0026] The machining up to this point may be performed by gripping the columnar material W' with the second work spindle 22. In this case, similarly, the vicinity of the end of the shaft-like portion 52 is gripped, and the shaft-like portion 53 is turned while rotating the columnar material W' around the central axis A (rotational machining axis C'), and the gear cutting circumferential portion 51' is machined to obtain the gear cutting portion 51. In the next step, the shaft-like portion 53 is gripped by the first work spindle. At this time, the workpiece W obtained by machining the columnar material W' can be automatically transferred from the second work spindle 22 to the first work spindle 12 simply by the operation of the machining device 1, without manual operation by an operator.

[0027] 5A, the workpiece W obtained by forming the gear cutting portion 51 on the columnar material W' is temporarily removed from the first workpiece spindle 12 or transferred from the second workpiece spindle 12. One end of the workpiece W, i.e., the turned shaft portion 53, is gripped by the first workpiece spindle 12, and the workpiece W is attached to the workpiece spindle 12 so that the axis A' (see FIG. 2) is aligned with the rotary processing axis C (S4). At this time, the central axis A of the gear cutting portion 51 of the workpiece W may become eccentric from the rotary processing axis C of the first workpiece spindle 12. Such eccentricity occurs when the first workpiece spindle 12 changes the grip of the workpiece W or when the workpiece W is transferred from the second workpiece spindle 22.

[0028] 5B, in this embodiment, the shape and the like of the gear cutting portion 51 are measured using the rotary machining axis C as a reference (S5). For example, the phase and pitch of the teeth 51a of the gear cutting portion 51 are measured using the rotary machining axis C as a reference. For such measurements, a touch probe 34a attached to the tool holding device 33a can be used as a measuring device. Note that, since the rotary machining axis C is used as a reference, it is preferable to measure the phase and pitch while rotating the workpiece W around the rotary machining axis C.

[0029] Here, the measurement data of the phase and pitch are sent from the control device 40 of the processing device 1 to the calculation device 41. Then, the calculation unit 43 calculates the deviation of the central axis A of the gear cutting portion 51 from the rotary processing axis C of the first workpiece spindle 12. In other words, the amount of eccentricity of the central axis A from the rotary processing axis C and the rotational phase difference (eccentric direction) can be calculated as the deviation.

[0030] The calculation device 41 then determines whether or not eccentricity exists (S6). Here, if the calculated amount of eccentricity of the central axis A, i.e., the amount of eccentricity of the central axis A relative to the rotary machining axis C of the first workpiece spindle 12, is within a predetermined range, it is determined that there is no eccentricity (S6; No). Then, the turning and drilling of the shaft-shaped portion 52 is performed as usual, such as by turning around the rotary machining axis C of the first workpiece spindle 12 (S8).

[0031] On the other hand, if the amount of eccentricity exceeds the predetermined range, it is determined that eccentricity exists (S6; Yes). Then, based on the obtained amount and direction of eccentricity, i.e., based on the calculated deviation, eccentric machining is performed on the shaft-shaped portion 52 from the other end side of the workpiece W with respect to the rotary machining axis C (S7). In eccentric machining, a tool holding device 33a that holds a cutting tool such as a turning tool 34b is used as a cutting device.

[0032] For example, as shown in FIG. 5C , while the workpiece W is rotated around the rotary machining axis C of the first workpiece spindle 12, the turning tool 34b is moved in the radial direction (X-axis direction) in synchronization with the rotation of the workpiece W so as to be based on the central axis A of the gear cutting portion 51, thereby eccentrically machining the outer peripheral surface of the shaft-shaped portion 52. In other words, eccentric machining is performed with respect to the rotary machining axis C based on the amount and direction of eccentricity of the central axis A with respect to the rotary machining axis C. Also, for example, the end of the shaft-shaped portion 52 is drilled to form a hole 52a with respect to the central axis A. In such drilling, for example, a pilot hole is formed by cutting with a rotary tool 34c such as a U-drill held by the tool holding device 33a, and then the hole is expanded with a rotary tool 34c such as an end mill, or the inner diameter is turned with a turning tool. In the hole expanding process using the rotating rotary tool 34c and the turning process using the turning tool, cutting is performed eccentrically with respect to the rotary processing axis C so that cutting is performed around the central axis A.

[0033] With a gear component obtained in this manner, the shaft-shaped portion 52 at the other end of the workpiece W can be precisely machined using the central axis A of the gear cutting portion 51 as a reference. In other words, machining based on the central axis A of the gear cutting portion can correct any deviation in the central axis due to workpiece re-holding or other machining defects. Note that deviation in the central axis due to workpiece re-holding occurs when the workpiece is gripped by a new workpiece spindle after the gear cutting portion is formed. In other words, deviation in the central axis can occur whether the workpiece is re-held using the same workpiece spindle, transferred using a different workpiece spindle, or a workpiece that has been gear-cut using a different machining device is gripped. These deviations can then be corrected using the method described above.

[0034] In the above example, a workpiece W having a gear cutting portion 51 machined on the outer periphery of a stepped columnar shape is machined to machine an axial portion 52 adjacent to the gear cutting portion 51 in the direction of the axis A', but the shape of the workpiece and the machining location are not limited to this.

[0035] For example, if the workpiece is a columnar part with gears cut along a portion of the circumference along the axis A', the gear formed by the gear cutting portion may be an internal gear or a bevel gear. Here, for convenience, even if the shape of the workpiece is a part that is short in dimension along the central axis of the gear cutting portion or a part with a hole inside the gear cutting portion, it is considered a columnar part extending along the axis A'. Furthermore, the machining area is the same regardless of the shape of the gear product, as long as the gear cutting portion of the workpiece W is cut around the rotary machining axis C (and thus the central axis A) by gripping one end of the workpiece W along the axis A' and approaching a cutting tool from the other end. For example, such machining areas include the outer periphery or inner periphery of a portion adjacent to or separated from the gear cutting portion along the axis A', or the inner periphery of the gear cutting portion. Furthermore, regarding the portion to be machined after gear cutting, the portion whose central axis should be aligned with the central axis of the gear cutting portion, i.e., the portion requiring eccentric machining, varies depending on the application of the product. Therefore, among the portions to be machined after gear cutting, portions to be machined by turning as usual around the rotary machining axis regardless of whether or not there is eccentricity may be included.

[0036] The above-described processing method is particularly suitable for gear components that require the workpiece to be changed over or handed over after gear cutting, such as when drilling a bottomed hole in the center of a substantially circular gear from both axial sides. Furthermore, when the gear cutting is performed by milling, it is more difficult to align the center axis of the gear cutting portion with the rotational processing axis than when cutting with a hob cutter, so the above-described processing method is also suitable in such cases. Note that, as long as the gear component has gears cut on the outer periphery of the workpiece, pitch measurement is easy regardless of the shape, and the above-described processing method can be suitably used.

[0037] The same applies to a gear component in which a shaft hole is formed after gear cutting, as shown in FIG. 6A . Here, the outer periphery of a substantially disk-shaped workpiece W1 is defined as a gear cutting portion 61. The gear cutting portion 61 is formed by gear cutting around a central axis A. After gear cutting, the workpiece W1 is gripped by a processing device that performs a drilling process. The coordinates of the gear cutting portion 61 are measured around the rotary processing axis C of the processing device. Then, the deviation of the central axis A of the gear cutting portion 61 from the rotary processing axis C is calculated. Here, the deviation is calculated, for example, as an eccentricity amount L and a rotational phase difference α. Then, to form a shaft hole, a pilot hole 63 is drilled, for example, based on the rotary processing axis C. At this time, the rotary processing axis C, which is the center of the pilot hole 63, is deviated from the central axis A by the eccentricity amount L.

[0038] 6B, the hole expanding process is performed eccentrically so that the center of the axial hole 64 coincides with the central axis A while rotating the workpiece W1 around the rotary processing axis C of the processing device. This also makes it possible to perform processing that accurately forms the axial hole 64 with the central axis A of the gear cutting portion 61 as a reference by performing eccentric processing with respect to the rotary processing axis C so as to correct the misalignment.

[0039] When measuring the gear cutting portion, the measurement points are the intersections of the pitch circle and the tooth surface, and measurement values ​​can only be obtained at intermittent points. As a result, the measurement points do not coincide with the eccentricity direction, resulting in an error between the rotational phase difference calculated from the measurement points and the actual rotational phase difference. This error tends to be particularly large when the number of teeth is small. When measuring the gear cutting portion, performing pitch measurement in this way to calculate the amount of eccentricity, etc., is preferable because it increases the concentricity between the gear cutting portion and other parts. Furthermore, errors due to hob eccentricity do not affect the outer circumference (tooth tip), and therefore can only be detected by pitch measurement.

[0040] As described above, if the rotational phase difference calculated from the measurement points contains an error, for example, a method can be used in which a least-squares circle is calculated from a graph plot of the relationship between the pitch error and phase at each measurement point obtained from the measurement values, and a cosine curve that fits this can be obtained. The apex of the obtained cosine curve can be determined as the rotational phase difference, thereby obtaining an accurate direction and amount of eccentricity. The direction and amount of eccentricity may also be determined by other known methods. Furthermore, the presence or absence of eccentricity can be automatically determined using such a graph of the relationship between pitch error and phase. For example, the value of correlation with the cosine curve of the graph can be calculated, and the presence or absence of eccentricity can be determined based on this value.

[0041] While the exemplary embodiments and accompanying modifications of the present invention have been described above, the present invention is not necessarily limited thereto and may be modified as appropriate by those skilled in the art. In other words, those skilled in the art will be able to find various alternative embodiments and modifications without departing from the scope of the appended claims.

[0042] REFERENCE SIGNS LIST 1 Machining device 12 First workpiece spindle 22 Second workpiece spindle 30 Moving device 33a Tool holding device 34a Touch probe (measuring instrument) 34b Turning tool 34c Rotating tool 40 Control device 41 Calculating device 45 Automatic tool changer 51 Gear cutting portion 51a Tooth portion 52, 53 Shaft-shaped portion A Central axis C Rotational machining axis W Workpiece W' Columnar material

Claims

1. A method for processing gear components, comprising: gripping a cylindrical workpiece having a gear cutting portion machined on a partial circumference along an axis with the workpiece spindle at one end so that the axis is aligned with a rotary processing axis; measuring the gear cutting portion to calculate the deviation of the central axis of the gear cutting portion from the rotary processing axis; and performing eccentric processing from the other end with respect to the rotary processing axis based on the deviation.

2. A method for machining a gear component according to claim 1, wherein the measurement of the gear cutting portion is performed by measuring the pitch of the teeth of the gear cutting portion while rotating the workpiece around the rotary machining axis.

3. A gear component processing method according to claim 2, wherein the deviation consisting of the amount and direction of eccentricity of the central axis relative to the rotary processing axis is calculated from the rotational phase difference of the tooth portions of the gear cutting portion.

4. A method for machining a gear component according to any one of claims 1 to 3, wherein the eccentric machining is performed while rotating the workpiece around the rotary machining axis.

5. A gear component machining method according to any one of claims 1 to 3, wherein the eccentric machining is performed using a rotating tool.

6. A method for machining a gear component according to any one of claims 1 to 3, wherein the gear cutting portion is machined on the outer periphery of the workpiece.

7. A method for processing gear components according to any one of claims 1 to 3, wherein, in order to process a columnar material into the workpiece, the columnar material is gripped by the workpiece spindle, the one end side of the workpiece in the columnar material is turned, and the gear cutting portion is machined.

8. A gear component processing program that measures the gear cutting portion by gripping the workpiece with a work spindle at one end of a cylindrical workpiece having a gear cutting portion machined on a partial circumference along an axis so that the axis is aligned with a rotary processing axis, calculates the deviation of the central axis of the gear cutting portion from the rotary processing axis from the measured value, and performs eccentric processing on the other end of the workpiece relative to the rotary processing axis based on the calculated deviation.

9. A gear component machining program according to claim 8, wherein the measurement of the gear cutting portion measures the pitch of the teeth of the gear cutting portion while rotating the workpiece around the rotary machining axis.

10. A gear component machining program as set forth in claim 9, wherein the deviation consisting of the amount and direction of eccentricity of the central axis relative to the rotary machining axis is calculated from the rotational phase difference of the tooth portion of the gear cutting portion.

11. A gear component machining program as described in any one of claims 8 to 10, wherein, in order to machine a columnar material into the workpiece, the columnar material is gripped by the workpiece spindle, the one end side of the workpiece in the columnar material is turned, and the gear cutting portion is machined.

12. A machining apparatus comprising: a first work spindle that rotatably grips a workpiece; a tool holding device that holds a measuring instrument or a tool; a moving device that can move the first work spindle and the tool holding device relatively; and a control device that controls the driving of the first work spindle, the tool holding device, and the moving device, wherein in accordance with a machining program, the first work spindle holds a cylindrical workpiece having a gear cutting portion machined on a partial circumference along an axis, at one end side of the workpiece so that the axis is along a rotary machining axis, the measuring instrument held by the tool holding device measures the gear cutting portion, calculates the deviation of the central axis of the gear cutting portion from the rotary machining axis from the measured value, and, based on the calculated deviation, performs eccentric machining of the workpiece from the other end side of the workpiece with respect to the rotary machining axis using the tool held by the tool holding device.

13. A processing device according to claim 12, further comprising a second work spindle for rotatably gripping a workpiece, wherein, in order to machine a columnar material into the workpiece, the columnar material is gripped by the second work spindle, the one end side of the workpiece in the columnar material is turned, and the gear cutting portion is machined.

14. The processing device according to claim 12 or 13, further comprising an exchange device that enables the tool and the measuring device held by the tool holding device to be exchanged.

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