JP7613097B2 - Gear Processing Equipment - Google Patents

Description

The present invention relates to a gear processing device.

Conventionally, when a gear machining device is used to create teeth on a workpiece, phase alignment is performed to align the phase of the machining tool with that of the workpiece when the workpiece is detached during the gear machining process. In this case, it is necessary to detect the tooth phase of the workpiece by placing a workpiece detection sensor at a detection position that detects the tooth phase. For this reason, Patent Documents 1, 2, and 3 disclose techniques for gear machining devices that detect the tooth phase of the workpiece by placing a workpiece detection sensor at a detection position.

JP 2013-252582 A Japanese Patent Application Publication No. 6-55341 International Publication No. 2020/031377

In the above conventional gear machining apparatus, the workpiece detection sensor is attached to a fixed mechanical part of the gear machining apparatus, and there is little freedom to move the workpiece detection sensor relative to the workpiece. As a result, in the conventional gear machining apparatus, the target for detecting the tooth phase is fixed to only one of the external teeth or internal teeth formed on the workpiece. In addition, in the conventional gear machining apparatus, it is necessary to position the workpiece detection sensor in response to the detection position that changes depending on the diameter of various workpieces, and in this case, a separate positioning device corresponding to the diameter of various workpieces is required.

The present invention aims to provide a gear machining device that has a simplified configuration and improves the degree of freedom of movement of the workpiece detection sensor relative to the workpiece.

The gear machining device is a gear machining device which creates teeth by cutting the peripheral surface of the workpiece while rotating the machining tool and the workpiece synchronously and feeding them relatively, and which comprises a tool holding device which holds the machining tool rotatably and movable relative to the workpiece, a workpiece holding device which holds the workpiece rotatably and movable relative to the machining tool, a workpiece detection sensor which is provided on the tool holding device so as to be approachable or moveable away from the workpiece held by the workholding device and which detects the rotational position of the teeth of the workpiece, a position control unit which controls the positions of the tool holding device and the workholding device so as to be movable relative to each other and controls the approach or move away of the workpiece detection sensor to the workpiece, and a gear machining device which performs a gear cutting process based on the detection result of the workpiece detection sensor. and a control device including a phase detection unit that detects the tooth phase of the workpiece by detecting the tooth phase of the workpiece through a position control unit that moves the tool holding device and the work holding device relative to each other when detecting the tooth phase of the workpiece, and controls the position of the workpiece detection sensor so that the sensor is located at a detection position where the tooth phase is detected by approaching the workpiece to the workpiece, and the tool holding device has a rotating spindle that supports and rotates the machining tool, and a spindle housing that rotatably supports the rotating spindle, and the workpiece detection sensor is provided in a sensor casing that is integrally connected to the spindle housing so as to be movable forward and backward in the direction of the rotation axis of the rotating spindle and unable to be relatively displaced in the radial direction of the rotating spindle. a sensor casing that supports a movable rod that advances and retreats in the direction of the axis of rotation of the rotating main shaft and a drive device that advances and retreats the movable rod; the workpiece detection sensor is assembled so as not to be displaceable relative to the movable rod, and is accommodated in an accommodation space formed inside the sensor casing as the movable rod retreats during cutting, and is positioned at the detection position by passing through an opening provided in the accommodation space as the movable rod advances when detecting the tooth phase of the workpiece, and the accommodation space is configured so that foreign matter generated during cutting is at least accommodated in the accommodation space during cutting. The movable rod has a seal mechanism that prevents the workpiece from entering the movable rod side beyond the workpiece detection sensor, and a workpiece detection sensor is attached to the tip of the movable rod and is housed in a case formed with a larger diameter than the movable rod. The seal mechanism has a first seal portion arranged opposite the outer peripheral surface of the case, a second seal portion arranged adjacent to the first seal portion in the axial direction of the case and having a step consisting of a large diameter portion surrounding the outer peripheral surface of the case and a small diameter portion surrounding the outer peripheral surface of the movable rod, and a third seal portion that slides against the outer peripheral surface of the movable rod and is arranged on the opposite side of the first seal portion to the second seal portion in the direction of the rotation axis of the rotating shaft.
The gear machining device is a gear machining device which relatively feeds a machining tool having a tool blade and a workpiece while rotating them synchronously, and cuts the inner peripheral surface of the workpiece to generate teeth, and includes a tool holding device which holds the machining tool rotatably and movable relative to the workpiece, a workpiece holding device which holds the workpiece rotatably and movable relative to the machining tool, and a machining device which is provided on the tool holding device so as to be approachable to or moveable away from the workpiece held by the workpiece holding device, and which detects the rotational position of the teeth of the workpiece. a control device including a work detection sensor, a position control unit which controls the positions of the tool holding device and the work holding device so as to be relatively movable and controls the approach or separation of the work detection sensor to the work, and a phase detection unit which detects a tooth phase of the work based on a detection result of the work detection sensor, wherein the position control unit moves the work detection sensor away from the work during cutting processing by the machining tool, while moving the tool holding device and the work holding device relatively when detecting the tooth phase of the work, a position control device for controlling the position of the workpiece detection sensor so that the workpiece detection sensor approaches the workpiece and is located at a detection position where the tooth phase is detected, the detection position being a position facing an inner periphery of the workpiece, the tool holding device has a rotating spindle which supports and rotates the machining tool, and a spindle housing which rotatably supports the rotating spindle, the workpiece detection sensor is provided in a sensor casing which is integrally connected to the spindle housing so as to be movable forward and backward in the direction of the rotation axis of the rotating spindle and unable to move relatively in the radial direction of the rotating spindle, a workpiece detection sensor that moves away from the workpiece during the cutting process using a tool and is positioned at the detection position when detecting the tooth phase of the workpiece, the sensor casing supports a movable rod that moves back and forth in the direction of the rotation axis of the rotating spindle and a drive unit that moves the movable rod back and forth, the workpiece detection sensor is attached to the tip of the movable rod so as not to be displaced relative to the movable rod, and the position control unit drives the drive unit to extend the movable rod toward the workpiece in the direction of the rotation axis of the rotating spindle.

According to this, the position control unit of the control device can move the workpiece detection sensor away from the workpiece during cutting processing of the workpiece, and position the workpiece detection sensor at the detection position when detecting the tooth phase. The position control unit can also control the positions of the tool holding device and the workpiece holding device so that they can move relative to each other. As a result, even if a separate positioning device is not provided to move the workpiece detection sensor to the detection position in accordance with the diameter of the workpiece, the position control unit can move the tool holding device and the workpiece holding device relative to each other and then move the workpiece detection sensor closer to the workpiece, thereby positioning the workpiece detection sensor at the detection position. Therefore, the configuration of the gear machining device can be simplified to improve the degree of freedom of movement of the workpiece detection sensor relative to the workpiece, and the tooth phase of the workpiece W can be detected with high accuracy.

FIG. 1 is a diagram showing an overall configuration of a gear machining device. FIG. 2 is a perspective view showing a configuration of a rotating main shaft in FIG. 1 . FIG. 2 is a partial cross-sectional view showing the configuration of a machining tool (skiving cutter). FIG. 4 is a perspective view showing a configuration of a support mechanism. FIG. 5 is an enlarged cross-sectional view showing details of the sealing mechanism of FIG. 4 . FIG. 2 is a block diagram of a control device. 4 is a flowchart of a gear machining process executed by the control device. 13 is a flowchart of a phase alignment process executed in the gear machining process. 1 is a diagram showing a state in which the rotating spindle (and the workpiece detection sensor) are disposed at a first position. FIG. 10 is a diagram showing a state in which the rotating spindle (and the workpiece detection sensor) are moved integrally from the first position in FIG. 9 to a second position. 11 is a diagram showing a state in which the rotating spindle and the workpiece detection sensor are moved together from the second position in FIG. 10 to place the workpiece detection sensor at a detection position relative to the workpiece. 11 is a perspective view for explaining a state in which the workpiece detection sensor is placed at a detection position by the support mechanism. FIG. 13 is a diagram showing an example of output information (voltage change) output from a workpiece detection sensor to a phase detection unit. FIG.

(1. Applicable gear machining device)
The gear machining device cuts a gear into the workpiece by varying the rotation speed of the machining tool and the workpiece and moving the machining tool relative to the workpiece along the rotation axis of the workpiece (feeding operation) while rotating the machining tool and the workpiece synchronously. In this example, the gear machining device is equipped with a skiving cutter as the machining tool, and a gear is machined into the workpiece by skiving. In this example, the gear machining device can be exemplified as a machining center having three mutually orthogonal linear axes (X-axis, Y-axis, and Z-axis) and two rotation axes (A-axis (turntable axis) and C-axis (workpiece axis)) as drive axes. In this example, the direction parallel to the X-axis and Z-axis is the horizontal direction, and the direction parallel to the Y-axis is the vertical direction.

(2. Configuration of gear machining device 1)
1, the gear machining apparatus 1 mainly includes a bed 10, a column 20, a saddle 30, a spindle device 40, a table 50, a tilt table 60, a turntable 70, a holder 80, a tool changer 90, and a control device 100. In this example, the column 20, the saddle 30, and the spindle device 40 constitute a "tool holding device." Also, in this example, the table 50, the tilt table 60, the turntable 70, and the holder 80 constitute a "workpiece holding device."

The bed 10 is formed in a substantially rectangular shape and is arranged in a horizontal direction. An X-axis ball screw (not shown) is arranged on the upper surface of the bed 10 to drive the column 20 in a direction parallel to the X-axis, i.e., in the horizontal direction. An X-axis motor 11 is also arranged on the bed 10 to rotate the X-axis ball screw.

A Y-axis ball screw (not shown) is disposed on the side surface (sliding surface) 20a of the column 20 parallel to the Y-axis, for driving the saddle 30 in a direction parallel to the Y-axis, i.e., in the vertical direction. A Y-axis motor 21 is disposed on the column 20 to rotate the Y-axis ball screw.

The saddle 30 supports the spindle unit 40 and, as described below, supports the workpiece detection sensor 45, which detects the shape of the workpiece W held on the turntable 70, specifically the phase of the generated teeth, together with the sensor casing 40b integrally connected to the spindle housing 40a. As a result, when the saddle 30 moves, the spindle unit 40 and the workpiece detection sensor 45 move together with the saddle 30.

Here, the workpiece W can have external teeth created (formed) on the outer circumferential surface, or internal teeth created (formed) on the inner circumferential surface. In this example, the workpiece W has external teeth. The workpiece W can also be a multi-stage gear shaft formed with multiple teeth adjacent to each other in the axial direction.

The spindle device 40 includes a rotating spindle 41. The rotating spindle 41 is arranged parallel to the Z-axis perpendicular to the X-axis. As shown in FIG. 2, the rotating spindle 41 is rotatably supported by a spindle housing 40a fixed to the saddle 30, and is rotated by a spindle motor 42 housed in the saddle 30 (or the column 20). The rotating spindle 41 supports a machining tool 43 via a tool holder 44. The machining tool 43 is attached to the tip of the rotating spindle 41 by being fitted into the tool holder 44 and fixed by a bolt (not shown), and rotates with the rotation of the rotating spindle 41.

The machining tool 43 and tool holder 44 move in a direction parallel to the X-axis, i.e., horizontally, relative to the bed 10 as the column 20 and saddle 30 move driven by the X-axis motor 11. Also, the machining tool 43 and tool holder 44 move in a direction parallel to the Y-axis as the column 20 and saddle 30 move driven by the Y-axis motor 21.

The machining tool 43 in this example is a skiving cutter, and is designed based on the shape of the tooth surface to be formed on the workpiece W (specifically, a gear). As shown in FIG. 3, the machining tool 43 has multiple tool blades 43a on the tool circumferential surface. In this example, the tool blades 43a are formed to have the same shape as the involute curve shape.

The tool blade 43a has a rake angle inclined by an angle γ with respect to a plane perpendicular to the rotation axis J of the cutting edge 43b. The tool blade 43a also has a clearance angle inclined by an angle δ with respect to a line parallel to the rotation axis J on the tool circumferential surface side. Furthermore, the cutting groove 43c of the tool blade 43a has a twist angle inclined by an angle β with respect to a line parallel to the rotation axis J. The machining tool 43 may also have a straight tool blade 43a that does not have a twist angle β and is parallel to the rotation axis J.

As shown in FIG. 3, the tool holder 44 is formed in a cylindrical shape with a tapered outer periphery, and is inserted at one end into a tapered hole provided in the rotating spindle 41 and fixed so as not to rotate relative to the rotating spindle 41, thereby forming a "rotating spindle body." The tool holder 44 is detachably supported by a detachment mechanism provided at the tip of the rotating spindle 41.

As shown in FIG. 3, the attachment/detachment mechanism has a draw bar inserted into the tool holder 44, a ball, and a support member that supports the ball. As a result, when the tool holder 44 is inserted into the tapered hole of the rotating spindle 41 and the draw bar and ball are inserted, and the draw bar moves rearward (downward in FIG. 3) away from the tool holder 44 as shown by the arrow in FIG. 3, the ball moves in the outer diameter direction (left and right direction in FIG. 3) and rearward along the taper formed in the draw bar. As a result, the tool holder 44 inserted into the tapered hole of the rotating spindle 41 is pulled and fixed as the draw bar and ball of the attachment/detachment mechanism move backward.

In this example, the workpiece detection sensor 45 is a non-contact sensor. Examples of the workpiece detection sensor 45 include an eddy current sensor, an electromagnetic pickup, and a laser sensor. In this example, the workpiece detection sensor 45 uses an eddy current sensor, and detects the shape of the gear formed on the workpiece W, specifically, the distance to the tooth tip and tooth root. The workpiece detection sensor 45 may also be a contact sensor, such as a touch probe sensor.

The workpiece detection sensor 45 is supported by a support mechanism 110 attached to the saddle 30, more specifically to the sensor casing 40b, so that the detection direction is parallel to the Y-axis, i.e., vertical. In other words, the workpiece detection sensor 45 is provided in the sensor casing 40b so that it can move forward and backward in the direction of the rotation axis J of the rotating main shaft 41 and cannot be displaced relative to the radial direction of the rotating main shaft 41.

As a result, when the workpiece detection sensor 45 does not detect the tooth phase (rotational position) of the workpiece W, the support mechanism 110 operates to accommodate the sensor 45 in the accommodation space 40c formed inside the sensor casing 40b in a state of being retracted (separated) from the workpiece W. On the other hand, when the workpiece detection sensor 45 detects the tooth phase (rotational position) of the workpiece W, the support mechanism 110 operates to advance the sensor casing 40b from the accommodation space 40c through an opening and approach the workpiece W (positioned at the detection position).

The support mechanism 110 is housed inside the sensor casing 40b, as shown in Figures 4 and 5. The support mechanism 110 mainly comprises a frame 111, a movable rod 112, a driving device 113, a connecting member 114, and a sealing mechanism 115. The frame 111 is fixed to the sensor casing 40b, and supports the movable rod 112, the driving device 113, the connecting member 114, and a part of the sealing mechanism 115.

The movable rod 112 can be advanced and retreated in the direction of the rotation axis J of the rotating main shaft 41 by the driving force of the drive unit 113. The movable rod 112 is supported by a bearing 112a fixed to the frame 111 so that it can move in the axial direction, i.e., the direction of the rotation axis J. A workpiece detection sensor 45 is attached to the tip of the movable rod 112 so that it cannot move relatively. As a result, the workpiece detection sensor 45 moves in the direction of the rotation axis J in conjunction with the advancement and retreat of the movable rod 112, and is in a state where it is retreated from the workpiece W (a state separated from it) and a state where it is advanced into the workpiece W (a state approaching it).

The driving device 113 is connected to the movable rod 112 via a connecting member 114, and moves the movable rod 112 in the direction of the rotation axis J. The driving device 113 is, for example, a rodless cylinder or a linear motor. Here, in this example, the movable rod 112 and the driving device 113 are arranged in a direction parallel to the Z axis of the gear machining device 1 (i.e., the vertical direction), in other words, arranged in two stages. The movable rod 112 and the driving device 113 are connected by a connecting member 114. This allows the dimension in the direction of the rotation axis J to be shortened compared to when the movable rod 112 and the driving device 113 are arranged (arranged) in a direction parallel to the X axis, for example.

The sealing mechanism 115 prevents coolant supplied when machining the gears on the workpiece W and chips generated during machining of the gears (hereinafter collectively referred to as "coolant, etc."), i.e., foreign matter, from entering the interior of the accommodation space 40c, more specifically, the movable rod 112 side of the workpiece detection sensor 45. As shown in FIG. 5, the sealing mechanism 115 is disposed inside the accommodation space 40c of the sensor casing 40b, and includes a first sealing portion 115a, a second sealing portion 115b, and a third sealing portion 115c.

The first seal portion 115a is made of an elastic material and is disposed adjacent to the annular thick portion 40b1 provided on the peripheral portion of the opening of the sensor casing 40b so as to be inside the accommodation space 40c in the direction of the rotation axis J. The first seal portion 115a is formed in an annular shape and disposed facing the outer peripheral surface of the cylindrical case 45a that houses the workpiece detection sensor 45, with a predetermined gap (e.g., about 0.2 mm on each side). As a result, the first seal portion 115a mainly prevents coolant and the like from entering the accommodation space 40c.

In this example, as shown in FIG. 5, the workpiece detection sensor 45 housed in the case 45a is disposed on the tip side (left side in FIG. 5) of the first seal portion 115a in the axial direction of the case 45a. Also, the case 45a is formed with an air supply passage 44a1 that supplies air to blow away coolant, etc. (foreign matter) adhering to the detection portion of the workpiece detection sensor 45 that has moved to the detection position, or coolant, etc. (foreign matter) that has entered the gap formed between the workpiece detection sensor 45 and the inner surface of the thick portion 40b1 at the opening.

As a result, air is supplied to the detection portion (tip portion) of the workpiece detection sensor 45 via the air supply path 44a1 before the workpiece detection sensor 45 detects the tooth phase (rotation position), thereby blowing away coolant, etc. (foreign matter) adhering to the detection portion of the workpiece detection sensor 45. Also, for example, by supplying air via the air supply path 44a1 before the workpiece detection sensor 45 detects the tooth phase (rotation position), the first seal portion 115a prevents the coolant, etc. (foreign matter) from entering the gap between the workpiece detection sensor 45 and the inner circumferential surface of the thick portion 40b1, i.e., the opening of the spindle housing 40a, can be blown away.

Therefore, when the workpiece detection sensor 45 detects the tooth phase (rotation position), that is, when the movable rod 112 approaches the workpiece W, the movement of the workpiece detection sensor 45 and the case 45a is not hindered by coolant, etc. (especially chips), and it is possible to prevent coolant, etc. from adhering to the detection portion of the workpiece detection sensor 45, making it unable to detect. The gap provided between the workpiece detection sensor 45 and the inner surface of the thick portion 40b1 is set so that coolant, etc. that has entered can be discharged to the outside by air supplied through the air supply path 44a1.

In this example, the first seal portion 115a is provided on the base end side of the case 45a (the connection side between the case 45a and the movable rod 112, the right side in FIG. 5) in the axial direction of the case 45a, further from the workpiece detection sensor 45. However, the first seal portion 115a can also be provided on the tip side of the case 45a, further from the workpiece detection sensor 45.

The second seal portion 115b is formed in a cylindrical shape from an elastic material and is disposed on the spindle motor 42 side in the direction of the rotation axis J with respect to the first seal portion 115a. The second seal portion 115b has a first inner circumferential portion 115b1 as a large diameter portion having an inner diameter slightly larger than the outer diameter of the case 45a of the workpiece detection sensor 45 formed on the tip side (right side in FIG. 5) and surrounding the outer circumferential surface of the case 45a, and a second inner circumferential portion 115b2 as a small diameter portion having a smaller diameter than the first inner circumferential portion 115b1 formed in the central portion and a larger diameter than the outer diameter of the movable rod 112.

As a result, as shown in FIG. 5, the second seal portion 115b has a step 115b3 formed by the first inner circumferential portion 115b1 and the second inner circumferential portion 115b2 along the outer surface of the case 45a of the workpiece detection sensor 45. The step 115b3 exerts a so-called labyrinth effect on the coolant that has passed through the first seal portion 115a and reached the second seal portion 115b, preventing the coolant from penetrating further inside.

Furthermore, the second seal portion 115b has a discharge passage 115b4 formed on the base end side (left side in FIG. 5). The discharge passage 115b4 extends in a direction parallel to the Z-axis (i.e., vertical direction). This allows the discharge passage 115b4 to discharge coolant, etc. that has passed through the step portion 115b3 of the second seal portion 115b by its own weight to a position separated from the movable rod 112, for example, to the outside of the accommodation space 40c of the spindle housing 40a.

The third seal portion 115c is made of an elastic material and is disposed on the spindle motor 42 side in the direction of the rotation axis J relative to the second seal portion 115b. The third seal portion 115c is formed in an annular shape and is in sliding contact with the outer circumferential surface of the movable rod 112 with a predetermined tightening margin. This prevents the coolant, etc. that has passed through the second seal portion 115b and reached the third seal portion 115c from reaching the bearing 112a in the direction of the axis of the movable rod 112. The provision of the third seal portion 115c prevents the coolant, etc. from reaching the bearing 112a, effectively preventing the movement of the movable rod 112 from being hindered.

As shown in FIG. 1, a Z-axis ball screw (not shown) is disposed on the upper surface of the bed 10 to drive the table 50 in a direction parallel to the Z-axis. A Z-axis motor 12 is disposed on the bed 10 to rotate the Z-axis ball screw.

A tilt table support 63 that supports the tilt table 60 is provided on the upper surface of the table 50. The tilt table 60 is provided on the tilt table support 63 so that it can rotate (swing) around the A-axis. The tilt table 60 is rotated (swinged) by an A-axis motor 61 arranged coaxially. A turntable 70 is provided on the tilt table 60 so that it can rotate around the C-axis. The tilt table 60 may use a rotating table axis that is perpendicular to the C-axis.

A holder 80 that holds the workpiece W so that it cannot rotate relative to the turntable 70 is attached. In this example, the turntable 70 and holder 80 constitute the "workpiece spindle." The turntable 70 is rotated together with the workpiece W and holder 80 by the C-axis motor 62. Here, the C-axis motor 62 is provided with an encoder 62a that detects the rotation angle around the C-axis.

The tool changer 90 automatically changes the machining tool 43 attached to the spindle unit 40 via the tool holder 44 with another machining tool 43 (and tool holder 44) stored in a tool magazine (not shown). The configuration and operation of the tool changer 90 are well known and can be found in, for example, JP 2018-103330 A, and therefore will not be described here.

The control device 100 is a computer device whose main components include a CPU, ROM, RAM, various interfaces, etc., and executes various programs. As shown in FIG. 6, the control device 100 mainly includes a tool rotation control unit 101, a workpiece rotation control unit 102, a tilt control unit 103, a position control unit 104, a phase detection unit 105, and a storage device 106.

The tool rotation control unit 101 controls the drive of the spindle motor 42 using the rotation angle detected by the encoder 42a, and rotates the tool holder 44 and the machining tool 43 together with the rotating spindle 41. The workpiece rotation control unit 102 controls the drive of the C-axis motor 62 using the rotation angle detected by the encoder 62a, and rotates the workpiece W held in the holder 80 together with the turntable 70 around the C-axis. The tilt control unit 103 controls the drive of the A-axis motor 61, and swings the tilt table 60, thereby swinging the turntable 70 and the workpiece W around the A-axis.

The position control unit 104 controls the position of the column 20, i.e., the saddle 30 supporting the rotating spindle 41 and workpiece detection sensor 45 of the spindle device 40, and the table 50, i.e., the tilt table support unit 63 fixed to the table 50, so that they can move relatively. The position control unit 104 controls the drive of the X-axis motor 11 to move the column 20 and the saddle 30 supported by the column 20 together in a direction parallel to the X-axis. The position control unit 104 also controls the drive of the Y-axis motor 21 to move the saddle 30 in a direction parallel to the Y-axis. As a result, the position control unit 104 moves the rotating spindle 41 and workpiece detection sensor 45 of the spindle device 40 supported by the saddle 30 together in a direction parallel to the X-axis and in a direction parallel to the Y-axis without causing any relative displacement.

The position control unit 104 also controls the operation of the support mechanism 110. That is, the position control unit 104 controls the drive of the drive device 113 of the support mechanism 110, and causes the movable rod 112 connected to the drive device 113 by a connecting member 114 to extend and retract in a direction parallel to the rotation axis J of the rotating main shaft 41. As a result, the position control unit 104 moves the workpiece detection sensor 45 attached to the tip of the movable rod 112 to a detection position where the workpiece detection sensor 45 detects the tooth phase of the gear formed on the workpiece W in a direction parallel to the rotation axis J of the rotating main shaft 41, as described below, and also moves it from the detection position to a storage position where it is stored in the storage space 40c.

Furthermore, the position control unit 104 controls the drive of the Z-axis motor 12 to move the table 50 and the tilt table support unit 63 supported by the table 50 together in a direction parallel to the Z-axis. As a result, the position control unit 104 moves the workpiece W supported by the tilt table support unit 63 in a direction parallel to the Z-axis.

The phase detection unit 105 detects the tooth phase of the gear formed on the workpiece W based on the signal (waveform) output from the workpiece detection sensor 45. The memory device 106 stores the detection results by the workpiece detection sensor 45. In addition to the detection results by the workpiece detection sensor 45, the memory device 106 also stores, for example, basic information about the gear to be formed on the workpiece W (information about various dimensions, number of teeth, etc.) and basic information about the machining tool 43.

(3. Gear Machining Process (Gear Machining Method))
Next, a gear cutting process executed by the control device 100 will be described with reference to the flowchart shown in Fig. 7. The gear cutting process is executed when a gear is formed on a workpiece W, which is a cylindrical blank, by gear cutting.

In the gear machining process, in step S1, as a rough machining process, gear machining is performed on a cylindrical workpiece W held by a retainer 80, and a gear is formed on the workpiece W. In the subsequent step S2, as a hardening process, the gear machining process hardens the workpiece W on which the gear has been formed by the rough machining process.

In the gear machining process, in step S3, a phase alignment process is performed when the hardened workpiece W is held again in the retainer 80, or when the machining tool 43 and tool holder 44 are attached or replaced by the tool changer 90. In this example, the phase alignment process detects the tooth phase (rotational position) of the external teeth formed on the workpiece W held in the retainer 80, as described in detail later. Then, in the phase alignment process, a phase alignment is performed to align the detected tooth phase (rotational position) of the external teeth of the workpiece W with the separately detected tool phase (rotational position) of the machining tool 43.

Once phase alignment is performed in the phase alignment process, the gear machining process proceeds to a finish machining process in step S4. The finish machining process performs finish machining of the gear on the workpiece W. If the workpiece W after gear machining is hardened, distortion occurs in the workpiece W. Therefore, it is common to perform gear machining again on the hardened workpiece W to improve the accuracy of the gear. In this case, the gear machining device 1 needs to determine the tooth phase of the workpiece W held in the retainer 80 and then perform phase alignment between the workpiece W and the machining tool 43.

In other cases, for example, when a workpiece W that has already been roughly machined using a hob cutter or the like is subjected to finish machining using the machining tool 43, gear machining may be performed on the workpiece W on which a gear has already been formed. In this case, the gear machining device 1 must grasp the tool phase of the machining tool 43 and the tooth phase of the workpiece W held (fixed) in the retainer 80, and perform phase alignment between the workpiece W and the machining tool 43. Furthermore, in this example, the machining tool 43 is a skiving cutter, which has a relatively short tool life compared to, for example, a hob cutter, and the machining tool 43 must be replaced more frequently. As a result, in the gear machining device 1 of this example, phase alignment between the tooth phase of the workpiece W and the tool phase of the machining tool 43 must be performed more frequently.

In this regard, the gear machining device 1 of this example detects the tool phase (rotational position) of the machining tool 43 using a tool detection sensor (not shown), which is a non-contact sensor such as an eddy current sensor or a contact sensor such as a touch probe sensor, that detects the tool phase of the machining tool 43. The gear machining device 1 then moves the column 20 and the saddle 30 and operates the support mechanism 110 to move and position the workpiece detection sensor 45 to a detection position for detecting the tooth phase (rotational position) of the external teeth of the workpiece W, and detects the tooth phase (rotational position) of the workpiece W. In this way, the gear machining device 1 of this example detects (detects) the tooth phase (rotational position) of the workpiece W, and the time required to align the phase of the workpiece W and the machining tool 43 can be shortened.

In this example, the workpiece detection sensor 45 detects the tooth phase (rotational position) of the external teeth of the workpiece W, so that the workpiece detection sensor 45 is disposed opposite the outer periphery of the workpiece W, as described below. However, in the gear machining device 1, the workpiece detection sensor 45 is not limited to detecting the tooth phase (rotational position) of the external teeth of the workpiece W, but can also detect the tooth phase (rotational position) of the internal teeth of the workpiece W. In this case, the gear machining device 1 disposes the workpiece detection sensor 45 opposite the inner circumference of the workpiece W, so that the workpiece detection sensor 45 can detect the tooth phase (rotational position) of the internal teeth of the workpiece W.

In the flowchart shown in FIG. 7, the gear machining process executes the phase alignment process in step S3, which is after the hardening process in step S2 and before the finish machining process in step S4. However, the phase alignment process can also be executed during the rough machining process in step S1 and the finish machining process in step S4. For example, if the machining tool 43 is damaged during the rough machining process in step S1 or the finish machining process in step S4 and the machining tool 43 is replaced, the gear machining process can execute the phase alignment process to align the phase between the workpiece W and the machining tool 43.

(4. Details of Phase Alignment of Workpiece W and Machining Tool 43 (Gear Machining Method))
Next, the phase alignment process executed in step S3 in the gear machining process (gear machining method) will be described in detail with reference to the flowchart shown in Fig. 8. Note that, when executing the phase alignment process, it is assumed that the tool phase (rotational position) of the machining tool 43 detected separately is stored in the memory device 106 of the control device 100.

In the phase alignment process executed in step S3, the control device 100 (specifically, the CPU; the same applies below) first executes a determination in step S11 as to whether or not the workpiece W has been detached in conjunction with the above-mentioned hardening process. That is, if the workpiece W has not been detached, the control device 100 determines "No" in step S11, and returns to the gear machining process shown in the flowchart of FIG. 7 to execute the finish machining process in step S4. On the other hand, if the workpiece W has been detached, the control device 100 determines "Yes" in step S11, and proceeds to step S12.

In step S12, the tilt control unit 103 of the control device 100 controls the drive of the A-axis motor 61, and swings the tilt table 60 so that the C-axis, which is the rotation axis of the workpiece W, and the rotation axis J of the machining tool 43 (rotating spindle 41) are parallel, as shown in FIG. 9. Then, after swinging the tilt table 60, the control device 100 proceeds to step S13.

In step S13, the phase detection unit 105 of the control device 100 determines the detection position of the workpiece detection sensor 45 based on the positional relationship between the rotating spindle 41 and the workpiece detection sensor 45 in the saddle 30 and the center position of the tool holder 44 that has been previously indexed. Then, the position control unit 104 of the control device 100 positions the workpiece detection sensor 45 at the detection position.

Specifically, the position control unit 104 moves the tool holder 44, i.e., the column 20 supporting the rotating spindle 41, which is disposed at the first position as shown in FIG. 9, to a second position as shown in FIG. 10 toward the detection position where the workpiece detection sensor 45 detects the tooth phase of the workpiece W. Then, the position control unit 104 moves the tool holder 44, i.e., the column 20 supporting the rotating spindle 41, which is disposed at the second position, to a third position corresponding to the detection position as shown in FIG. 11.

Here, the rotating spindle 41 is supported by the spindle housing 40a, and the workpiece detection sensor 45 is supported by a sensor casing 40b that is integrally connected to the spindle housing 40a. That is, the workpiece detection sensor 45 supported by the support mechanism 110 is supported so that the axis of the movable rod 112 and the rotation axis J of the rotating spindle 41 cannot be displaced relative to each other in the direction in which they move away from or toward each other. The spindle housing 40a and the sensor casing 40b are connected to the column 20 via the saddle 30.

11, when the column 20, i.e., the rotating spindle 41, is moved to the third position, the positional relationship between the rotating spindle 41 and the workpiece detection sensor 45 is maintained, so that the workpiece detection sensor 45 can move to a position corresponding to the detection position. That is, in the gear machining device 1, when detecting the tooth phase of the workpiece W, the column 20 (rotating spindle 41) is moved a preset distance in a direction parallel to the X-axis and a preset distance in a direction parallel to the Y-axis based on the positional relationship between the rotating spindle 41 and the workpiece detection sensor 45, using the first position (e.g., the retracted position of the rotating spindle 41 when the workpiece W is removed) as a reference.

Furthermore, with the rotating spindle 41 moved to the third position, the position control unit 104 drives the drive device 113 of the support mechanism 110 to extend the movable rod 112 toward the workpiece W in the direction of the rotation axis J. As a result, as shown in Figures 11 and 12, the workpiece detection sensor 45 attached to the tip of the movable rod 112 moves to a detection position where it detects the tooth phase of the workpiece W. This allows the workpiece detection sensor 45 to detect the tooth phase (rotational position) of the workpiece W.

Returning to the flowchart of FIG. 8 again, in step S14, the phase detection unit 105 of the control device 100 detects the tooth phase (rotational position) of the workpiece W. In this case, the phase detection unit 105 detects the tooth phase (rotational position) of the workpiece W by cooperating with the workpiece rotation control unit 102.

As shown in FIG. 12, the workpiece rotation control unit 102 controls the drive of the C-axis motor 62 to rotate the workpiece W in one direction at a low speed while the workpiece detection sensor 45 is positioned at the detection position by the support mechanism 110 under the drive control of the position control unit 104. In this example, the workpiece detection sensor 45 outputs a signal (e.g., a voltage) corresponding to the bottom surface of the external teeth of the workpiece W.

As a result, the phase detection unit 105 detects the tooth phase of the workpiece W based on the signal output by the workpiece detection sensor 45 and the rotation angle information of the workpiece W obtained from the encoder 62a provided on the C-axis motor 62. Specifically, when grasping the tooth phase of the workpiece W, the phase detection unit 105 detects the tooth phase of the workpiece W by performing a calculation using the output voltage information obtained from the workpiece detection sensor 45 and the rotation angle information obtained from the encoder 62a.

As shown in FIG. 13, the change in voltage output from the workpiece detection sensor 45 is a sine waveform that periodically rises and falls with the change in the rotation angle of the workpiece W. The phase detection unit 105 sets the intermediate value between the maximum and minimum voltage values as a threshold value Th, and extracts the rotation angle θ11 of the workpiece W when the voltage falls below the threshold value Th, and the rotation angle θ12 of the workpiece W when the voltage rises above the threshold value Th. The phase detection unit 105 then calculates the rotation angle θ1 that is the intermediate value between the rotation angles θ11 and θ12.

This rotation angle θ1 can be regarded as the rotation angle of the workpiece W when the detection position of the workpiece detection sensor 45 coincides with the center position of the bottom surface of the gear (external teeth) of the workpiece W. The phase detection unit 105 calculates (detects) the tooth phase of the center position of the bottom surface based on the calculation result and the basic information of the gear stored in the memory device 106. Then, when the control device 100 detects the tooth phase of the workpiece W, it executes the process of step S15.

When detecting the tooth phase, it is not necessary to rotate the workpiece W multiple times; it may be rotated at least once or by a rotation angle less than 360 degrees. In order to further improve the detection accuracy, the workpiece W may be rotated first in one direction and then in the other direction.

In step S15, the memory device 106 of the control device 100 stores tooth phase information representing the tooth phase (rotational position) of the workpiece W detected by the phase detection unit 105. Then, when the memory device 106 stores the tooth phase information, the control device 100 executes the process of step S16.

In step S16, the phase detection unit 105 of the control device 100 calculates the amount of deviation between the tooth phase of the workpiece W and the tool phase of the machining tool 43 based on the tool phase information representing the tool phase of the machining tool 43 that has been detected in advance and stored in the memory device 106, and the tooth phase information stored in the memory device 106 in step S15. Then, in cooperation with the tool rotation control unit 101 and the workpiece rotation control unit 102, the phase detection unit 105 aligns the phase of the workpiece W and the machining tool 43 based on the calculated amount of deviation.

Specifically, the tool rotation control unit 101 and the workpiece rotation control unit 102 adjust the rotation angles of the workpiece W and the machining tool 43 based on the deviation amount obtained by calculation so that the tooth phase of the workpiece W and the tool phase of the machining tool 43 match. Then, when the control device 100 finishes adjusting the rotation angles of the workpiece W and the machining tool 43, i.e., adjusting the initial machining position by phase matching, it returns to the gear machining process shown in the flowchart of FIG. 7 and executes the finish machining process in step S4.

As can be understood from the above explanation, according to the gear machining device 1, the position control unit 104 of the control device 100 can move the workpiece detection sensor 45 away from the workpiece W during cutting processing of the workpiece W, and position the workpiece detection sensor 45 at the detection position when detecting the tooth phase. In addition, the position control unit 104 can control the positions of the column 20 and saddle 30 forming the tool holding device, and the tilt table support unit 63 and turntable 70 forming the workpiece holding device so that they can move relative to each other.

As a result, for example, even without providing a separate positioning device to move the workpiece detection sensor 45 to the detection position in accordance with the diameter of the workpiece W, the position control unit 104 can move the column 20 and saddle 30 relative to the tilt table support unit 63 and turntable 70, and then move the workpiece detection sensor 45 closer to the workpiece W, thereby positioning the workpiece detection sensor 45 at the detection position. Therefore, the configuration of the gear machining device 1 can be simplified to improve the degree of freedom of movement of the workpiece detection sensor 45 relative to the workpiece W, and the tooth phase of the workpiece W can be detected with high accuracy.

In addition, since the degree of freedom of movement of the workpiece detection sensor 45 relative to the workpiece W can be improved, the gear machining device 1 can position the workpiece detection sensor 45 not only at a detection position that detects the tooth phase of the external teeth formed (created) on the workpiece W, but also at a detection position that detects the tooth phase of the internal teeth. Therefore, there is no need to replace the workpiece detection sensor 45 or adjust its position depending on whether external teeth or internal teeth are formed on the workpiece W, and it is possible to shorten the cycle time required for machining, for example.

The gear machining device 1 can also be provided with a seal mechanism 115 on the support mechanism 110 that supports the workpiece detection sensor 45 so that it can move back and forth. This can prevent coolant and other substances generated when performing gear machining (cutting) on the workpiece W from entering the accommodation space 40c formed in the spindle housing 40a. This prevents the operation of the movable rod 112 and the drive device 113 housed in the accommodation space 40c from being hindered by the entry of coolant and other substances, and allows the workpiece detection sensor 45 to be reliably positioned at the detection position. This can maintain the accuracy of tooth phase detection by the workpiece detection sensor 45.

(5. Other Examples)
In the above-described embodiment, the workpiece detection sensor 45 detects the distance to the workpiece W. The physical quantity detected by the workpiece detection sensor 45 is not limited to distance, and for example, the workpiece detection sensor 45 may detect the strength of an electromagnetic physical quantity or a direct displacement of a contact.

In addition, in the above-described example, the gear machining device 1 is equipped with a tool exchange device 90, which makes it possible to automatically exchange the machining tools 43 and the tool holders 44 according to the machining content of the workpiece W. However, it is not necessary for the gear machining device 1 to be equipped with the tool exchange device 90, and it is also possible to configure the gear machining device 1 without the tool exchange device 90.

In addition, in the above-mentioned example, only the workpiece detection sensor 45 is supported by the support mechanism 110 so that it can move forward and backward (approach or move away) on the sensor casing 40b fixed to the saddle 30 of the gear machining device 1. However, it goes without saying that it is possible to provide the sensor casing 40b with another sensor other than the workpiece detection sensor 45 that detects the machining state of the workpiece W.

Furthermore, in the above-described example, the machining tool 43 is a skiving cutter, and the gear machining device 1 is described as performing gear machining by skiving. In contrast, if the machining tool is a hob cutter, the gear machining device can perform gear machining by hobbing.

In this case, in the gear cutting device, the hob cutter and the workpiece are positioned so that the rotation axis of the hob cutter and the rotation axis of the workpiece intersect (e.g., are perpendicular). When cutting gears, the gear cutting device cuts gears into the workpiece by rotating the workpiece and the hob cutter, while feeding the hob cutter in the direction of the rotation axis (moving it relatively).

When a workpiece is removed or attached during processing, the gear machining device can detect the tool phase of the hob cutter and the tooth phase of the workpiece in the same manner as in the above-described example, and can align the phases of the workpiece and the hob cutter. Therefore, in this case as well, the same effect as in the above-described example can be obtained.

1...Gear machining device, 10...Bed, 11...X-axis motor, 12...Z-axis motor, 20...Column (tool holding device), 20a...Side, 21...Y-axis motor, 30...Saddle (tool holding device), 30a...Side, 40...Spindle device, 40a...Spindle housing, 40b...Sensor casing, 40b1...Thick part, 40c...Accommodation space, 41...Rotary spindle, 42...Spindle motor, 42a...Encoder, 43...Machining tool, 43a...Tool blade, 43b...Blade tip, 43c...Blade groove, 44...Tool holder, 45...Workpiece detection sensor, 45a...Case, 50...Table, 60...Tilt table, 61...A-axis motor, 62...C-axis motor, 62a...Encoder, 63...Tilt table support part (workpiece support device position), 63a...side surface, 64...tool detection sensor, 70...turntable (workpiece support device), 80...retainer (workpiece support device), 90...tool exchange device, 100...control device, 101...tool rotation control unit, 102...workpiece rotation control unit, 103...tilt control unit, 104...position control unit, 105...phase detection unit, 106...storage device, 110...support mechanism, 111...frame, 112...movable rod, 112a...bearing, 113...driving device, 114...connecting member, 115...seal mechanism, 115a...first seal portion, 115b...second seal portion, 115b1...first inner periphery (large diameter portion), 115b2...second inner periphery (small diameter portion), 115b3...step portion, 115c...third seal portion, W...workpiece

Claims (7)

A gear machining device that generates teeth by cutting a peripheral surface of a workpiece while rotating a machining tool and the workpiece synchronously and feeding the workpiece relatively, comprising:
a tool holding device that holds the machining tool rotatably and movable relative to the workpiece;
a workpiece holding device that holds the workpiece rotatably and movably relative to the machining tool;
a work detection sensor provided on the tool holding device so as to be approachable or moveable from the work held by the work holding device, the work detection sensor detecting a rotational position of a tooth of the work;
a control device including a position control unit that controls the positions of the tool holding device and the work holding device so that they are movable relative to each other and controls the approach or separation of the work detection sensor to the work, and a phase detection unit that detects a tooth phase of the work based on a detection result of the work detection sensor,
The position control unit is
a position control for moving the workpiece detection sensor away from the workpiece during cutting processing by the machining tool, while at the same time, when detecting the tooth phase of the workpiece, moving the tool holding device and the workpiece holding device relatively and bringing the workpiece detection sensor close to the workpiece to a detection position where the tooth phase is detected;
The tool holding device includes a rotating spindle that supports and rotates the machining tool, and a spindle housing that rotatably supports the rotating spindle,
the workpiece detection sensor is provided in a sensor casing that is integrally connected to the spindle housing so as to be movable forward and backward in a direction of a rotation axis of the rotating spindle and to be immovable relative to a radial direction of the rotating spindle, the workpiece detection sensor being spaced away from the workpiece during the cutting process by the machining tool and being located at the detection position when detecting the tooth phase of the workpiece ,
the sensor casing supports a movable rod that moves back and forth in a direction of a rotation axis of the main rotating shaft, and a drive device that moves the movable rod back and forth;
the workpiece detection sensor is assembled to the movable rod so as not to be displaced relative to the movable rod, and is accommodated in an accommodation space formed inside the sensor casing as the movable rod is retreated during the cutting process, and is positioned at the detection position by passing through an opening provided in the accommodation space as the movable rod advances when detecting the tooth phase of the workpiece,
the accommodation space accommodates a seal mechanism that prevents foreign matter generated during the cutting process from entering at least a portion of the workpiece detection sensor retracted in the accommodation space toward the movable rod, the seal mechanism preventing foreign matter generated during the cutting process from entering a portion of the workpiece detection sensor retracted in the accommodation space toward the movable rod,
The workpiece detection sensor is attached to the tip of the movable rod,
the workpiece detection sensor is disposed at a tip of the movable rod and is housed in a case having a diameter larger than that of the movable rod,
the sealing mechanism having a first seal portion arranged opposite the outer peripheral surface of the case, a second seal portion arranged adjacent to the first seal portion in the axial direction of the case and having a step consisting of a large diameter portion surrounding the outer peripheral surface of the case and a small diameter portion surrounding the outer peripheral surface of the movable rod, and a third seal portion in sliding contact with the outer peripheral surface of the movable rod and arranged on the opposite side of the first seal portion with respect to the second seal portion in the direction of the rotation axis of the rotating main shaft . The gear machining device according to claim 1 , wherein the first seal portion is disposed inside the accommodation space and adjacent to the opening of the sensor casing. 2. The gear machining device according to claim 1, wherein the case has an air supply passage that supplies air to a detection portion that detects the tooth phase of the workpiece detection sensor, the detection portion being located on the opening side of the sensor casing relative to the first seal portion when the case is accommodated in the accommodation space. the opening of the sensor casing has an annular thick portion at a periphery thereof,
4. The gear machining device according to claim 3, wherein a gap is provided between an inner circumferential surface of the thick-walled portion and an outer circumferential surface of the case, through which foreign matter generated during the cutting process is blown away to the outside of the accommodating space by air supplied through the air supply path . The gear machining device according to claim 1 , wherein the first seal portion, the second seal portion and the third seal portion are formed from an elastic material. 6. A gear machining device according to claim 1 , wherein the workpiece detection sensor detects the rotational position of the tooth based on a distance to the workpiece. A gear machining device that generates teeth by cutting an inner peripheral surface of a workpiece while rotating a machining tool having a tool blade and the workpiece synchronously and feeding the workpiece relatively, comprising:
a tool holding device that holds the machining tool rotatably and movable relative to the workpiece;
a workpiece holding device that holds the workpiece rotatably and movably relative to the machining tool;
a work detection sensor provided on the tool holding device so as to be approachable or moveable from the work held by the work holding device, the work detection sensor detecting a rotational position of a tooth of the work;
a control device including a position control unit that controls the positions of the tool holding device and the work holding device so that they are movable relative to each other and controls the approach or separation of the work detection sensor to the work, and a phase detection unit that detects a tooth phase of the work based on a detection result of the work detection sensor,
The position control unit is
a position control for moving the workpiece detection sensor away from the workpiece during cutting processing by the machining tool, while at the same time, when detecting the tooth phase of the workpiece, moving the tool holding device and the workpiece holding device relatively and bringing the workpiece detection sensor close to the workpiece to a detection position where the tooth phase is detected;
the detection position is a position facing an inner periphery of the workpiece,
The tool holding device includes a rotating spindle that supports and rotates the machining tool, and a spindle housing that rotatably supports the rotating spindle,
the workpiece detection sensor is provided in a sensor casing that is integrally connected to the spindle housing so as to be movable forward and backward in a direction of a rotation axis of the rotating spindle and to be immovable relative to a radial direction of the rotating spindle, the workpiece detection sensor being spaced away from the workpiece during the cutting process by the machining tool and being located at the detection position when detecting the tooth phase of the workpiece ,
the sensor casing supports a movable rod that moves back and forth in a direction of a rotation axis of the main rotating shaft, and a drive device that moves the movable rod back and forth;
the workpiece detection sensor is attached to a tip of the movable rod so as not to be displaceable relative to the movable rod,
The position control unit drives the drive device to extend the movable rod toward the workpiece in the direction of the rotation axis of the main rotation shaft.

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