Processing equipment

Abstract

The present invention provides a machining apparatus that can reduce the effort required to adjust the rotation start position of the machining tool and the workpiece. [Solution] A machining apparatus 101 that machines a workpiece W while synchronously rotating a machining tool 10 and the workpiece W comprises a workpiece spindle 123b, a steady position deviation calculation unit 145 configured to calculate the steady position deviation Dt of the machining tool 10 when the machining tool 10 is attached to the tool spindle 133b and the machining tool 10 is rotated at a constant tool rotation speed Vt, and the steady position deviation Dw of the workpiece W when the workpiece W is attached to the workpiece spindle 123b and the workpiece W is rotated at a constant workpiece rotation speed Vw, and a rotation start phase determination unit 146 that determines at least one of the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W based on the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

Description

[Technical Field]

[0001] This invention relates to a processing apparatus. [Background technology]

[0002] Conventionally, machining apparatuses that machine a workpiece while synchronously rotating the machining tool (the tool spindle that holds the machining tool) and the workpiece (the workpiece spindle that holds the workpiece) are known, as described in Patent Documents 1 and 2.

[0003] Patent Document 1 discloses a machining apparatus for gear skiving, comprising: a control parameter selection unit that selects control parameters (gain parameters) corresponding to the machining conditions of the workpiece to be machined; and a control unit that controls the rotational drive unit of the workpiece to be machined and the rotational drive unit of the machining tool based on the control parameters selected by the control parameter selection unit.

[0004] Furthermore, Patent Document 2 discloses a configuration for identifying the frequency of vibration undulations in relation to the positional deviation between the tool axis and the workpiece axis during machining. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-49555 [Patent Document 2] Patent No. 6781228 [Overview of the project] [Problems that the invention aims to solve]

[0006] When the tool spindle and workpiece spindle are rotationally driven, the actual positions of the tool spindle and workpiece spindle may lag behind the target position command. In this case, the state in which the tool spindle and workpiece spindle rotate at a constant rotational speed such that they have a predetermined rotational speed ratio is defined as the steady state, and the difference between the target position command at a certain time and the actual position achieved at the same time in this steady state is defined as the steady position deviation.

[0007] The steady-state position deviation may reduce the machining accuracy of the workpiece. To improve the machining accuracy of a workpiece, a workpiece for phase adjustment is placed in the machining equipment, and the rotation start phase of the machining tool is manually adjusted relative to the workpiece for position adjustment, which is time-consuming.

[0008] This invention has been made in view of the above problems, and aims to provide a machining apparatus that can reduce the effort required to adjust the rotation start position of the machining tool and the workpiece. [Means for solving the problem]

[0009] One aspect of the present invention is, A machining apparatus for machining a workpiece while synchronously rotating the machining tool and the workpiece, A tool spindle is configured to hold the machining tool and to rotate the machining tool, A workpiece spindle configured to hold the workpiece and rotate the workpiece, A steady-state position deviation calculation unit is configured to calculate the steady-state position deviation of the machining tool when the machining tool is mounted on the tool spindle and rotated at a constant tool rotation speed, and to calculate the steady-state position deviation of the workpiece when the workpiece is mounted on the workpiece spindle and rotated at a constant workpiece rotation speed. The machining apparatus includes a rotation start phase determination unit that determines at least one of the rotation start phase of the machining tool and the rotation start phase of the workpiece based on the difference between the steady position deviation of the machining tool and the steady position deviation of the workpiece. [Effects of the Invention]

[0010] According to one aspect of the present invention, since the operator does not need to manually adjust the starting position of the machining tool and the workpiece, the effort required to adjust the starting position of the machining tool and the workpiece can be reduced.

[0011] As described above, according to the above embodiment, it is possible to provide a machining apparatus that can reduce the effort required to adjust the rotation start position of the machining tool and the workpiece. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic perspective view showing the processing apparatus of Embodiment 1. [Figure 2] A block diagram showing the configuration of the control device in Figure 1. [Figure 3] A perspective view showing the machining tool of Embodiment 1. [Figure 4] A diagram illustrating the difference between the steady-state position deviation of the machining tool and the steady-state position deviation of the workpiece in Embodiment 1. [Figure 5] A diagram illustrating the process of making the difference between the steady-state position deviation of the machining tool and the steady-state position deviation of the workpiece zero in Embodiment 1. [Figure 6] In Embodiment 1, the graph shows the time change of the phase of the reference position when the machining tool and the workpiece are rotated while the reference position of the machining tool and the reference position of the workpiece are aligned, wherein (a) is a graph showing the time change of the phase of the reference position of the machining tool, and (b) is a graph showing the time change of the phase of the reference position of the workpiece. [Figure 7]In the first embodiment, this is a graph showing temporal changes in the phase of reference positions when a machining tool and a workpiece are rotated in a state where the reference position of the machining tool and the reference position of the workpiece are both changed, wherein (a) is a graph showing temporal changes in the phase of the reference position of the machining tool, and (b) is a graph showing temporal changes in the phase of the reference position of the workpiece. [Figure 8] Main flow related to the operation of a machining apparatus by the control device in the first embodiment. [Figure 9] Flowchart of rotation start phase processing in Fig. 8. [Figure 10] Flowchart of motor control processing in Fig. 8. [Figure 11] In Modification 1 of the first embodiment, this is a graph showing temporal changes in the phase of reference positions when a machining tool and a workpiece are rotated in a state where the reference position of the workpiece is changed, wherein (a) is a graph showing temporal changes in the phase of the reference position of the machining tool, and (b) is a graph showing temporal changes in the phase of the reference position of the workpiece. [Figure 12] In Modification 2 of the first embodiment, this is a graph showing temporal changes in the phase of reference positions when a machining tool and a workpiece are rotated in a state where the reference position of the machining tool is changed, wherein (a) is a graph showing temporal changes in the phase of the reference position of the machining tool, and (b) is a graph showing temporal changes in the phase of the reference position of the workpiece. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a machining apparatus will be described with reference to the drawings.

[0014] In the drawings for describing the present embodiment, unless otherwise specified, the horizontal direction is defined as the X-axis direction, the vertical direction orthogonal to the X-axis direction is defined as the Y-axis direction, and the direction orthogonal to both the X-axis direction and the Y-axis direction is defined as the Z-axis direction.

[0015] (First Embodiment) 1. Configuration of machining apparatus 101 Embodiment 1 will be described with reference to Figure 1. The processing apparatus 101 according to Embodiment 1 drives the processing tool and the workpiece relatively and processes the workpiece with the processing tool. As shown in Figure 1, the processing apparatus 101 according to Embodiment 1 is a gear processing apparatus for forming gears by processing the workpiece W with the processing tool 10 while synchronously rotating and moving the workpiece W and the processing tool 10 together.

[0016] The machining apparatus 101 in this embodiment 1 is a machining center. The machining center is configured to have interchangeable machining tools 10, and is capable of machining according to the installed machining tool 10. In this embodiment 1, the machining tool 10 is configured to be interchangeable and performs a machining operation selected from among several types of machining, including skiving, which will be described later. Note that in Figure 1, for the sake of explanation, the tool changer and the tool magazine that houses multiple machining tools 10 are omitted from the illustration.

[0017] The machining apparatus 101 of this embodiment 1 is based on a horizontal machining center. However, other configurations, such as a vertical machining center, can be applied to the machining apparatus 101 as needed. Furthermore, the machining apparatus 101 of this embodiment 1 can also be applied to a gear machining apparatus (a dedicated machining apparatus for gear skiving) that does not require the exchange of machining tools 10. In addition, the machining apparatus 101 of this embodiment 1 can be applied to the machining of other workpieces, such as screw machining.

[0018] As shown in Figure 1, the machining apparatus 101 has, for example, three mutually orthogonal linear drive axes (X axis, Y axis, and Z axis). The machining apparatus 101 is configured to allow the workpiece W and the machining tool 10 to move relative to each other in the X axis direction, Y axis direction, and Z axis direction.

[0019] Furthermore, the machining apparatus 101 has one rotary drive axis (B axis) for changing the relative orientation between the workpiece W and the machining tool 10. In this embodiment 1, the B axis is a rotary drive axis about an axis Yw parallel to the Y axis. The machining apparatus 101 also has a rotary drive axis (Ct axis) for rotating the machining tool 10 and a rotary drive axis (Cw axis) for rotating the workpiece W. The Cw axis is also called the A axis.

[0020] In this embodiment 1, the Ct axis is a rotational drive axis around the rotation axis Zt of the machining tool 10, which is parallel to the Z-axis direction. The Cw axis is a rotational drive axis around the rotation axis Zw of the workpiece W, which is a horizontal axis and can take an angle with respect to the Z-axis direction according to the B-axis angle. However, the rotation axis Zt of the machining tool 10 may be configured to take an angle with respect to both the Z-axis direction and the X-axis direction.

[0021] In the machining apparatus 101, the configuration for relative movement between the workpiece W and the machining tool 10 can be selected as appropriate. Below, an example is given in which the machining tool 10 is capable of linear movement in the Y-axis and Z-axis directions, the workpiece W is capable of linear movement in the X-axis direction, and the workpiece W is capable of rotation on the B-axis.

[0022] The machining apparatus 101 comprises a bed 110, a workpiece holder 120, a tool holder 130, and a control unit 140. The bed 110 is installed on a mounting surface and is formed in a shape corresponding to the shape of the workpiece holder 120 and the shape of the tool holder 130. In this embodiment 1, for example, the bed 110 is rectangular in shape when viewed from the Y-axis direction. A pair of X-axis guide rails 111 and a pair of Z-axis guide rails 112 are provided on the upper surface of the bed 110. Both of the pair of X-axis guide rails 111 extend in the X-axis direction with the Y-axis direction as the thickness direction. Both of the pair of Z-axis guide rails 112 extend in the Z-axis direction with the Y-axis direction as the thickness direction.

[0023] The workpiece holding device 120 mainly comprises an X-axis moving table 121, a B-axis rotating table 122, a workpiece spindle device 123, and a tool phase detection unit 126. The X-axis moving table 121 is driven by a drive device such as a linear motor or a ball screw mechanism (not shown) and is configured to move in the X-axis direction while being guided by the X-axis guide rail 111 of the bed 110.

[0024] The B-axis rotary table 122 is mounted on the upper surface of the X-axis moving table 121 and is configured to move integrally with the X-axis moving table 121 in the X-axis direction. The B-axis rotary table 122 is also provided so as to be rotatable on the B-axis relative to the X-axis moving table 121. This B-axis rotary table 122 is equipped with a rotary motor and a rotation angle detector (not shown). Therefore, the B-axis rotary table 122 becomes rotatable on the B-axis by driving the rotary motor.

[0025] The workpiece spindle device 123 is mounted on the B-axis rotary table 122 and is configured to rotate integrally with the B-axis rotary table 122. The workpiece spindle device 123 rotatably holds the workpiece W. The workpiece spindle device 123 comprises a housing 123a, a workpiece spindle 123b, a workpiece motor 124 that rotationally drives the workpiece spindle 123b, and an encoder 125 (see Figure 2) that detects the rotation angle of the workpiece motor 124.

[0026] The housing 123a of the workpiece spindle unit 123 is fixed to the B-axis rotary table 122, and the workpiece spindle 123b of the workpiece spindle unit 123 is rotatably supported by the housing 123a. The workpiece W is attached to the tip of this workpiece spindle 123b. In other words, the workpiece W is cantilevered by the workpiece spindle 123b of the workpiece spindle unit 123. The workpiece motor 124 is a servo motor controlled by the control unit 140. The workpiece spindle unit 123 makes the workpiece W rotatable on the Cw axis by the drive of the workpiece motor 124. In this way, the workpiece holding device 120 makes the workpiece W movable in the X-axis direction relative to the bed 110, rotatable on the B axis, and rotatable on the Cw axis.

[0027] The tool holding device 130 mainly comprises a column 131, a saddle 132, a tool spindle device 133, and a workpiece phase detection unit 136. The column 131 is driven by a drive device such as a linear motor or a ball screw mechanism (not shown) and moves in the Z-axis direction while being guided by the Z-axis guide rail 112 of the bed 110. A Y-axis guide rail 131a is formed on the vertically extending side surface of the column 131 (left surface in Figure 1). The saddle 132 is driven by a drive device such as a linear motor or a ball screw mechanism (not shown) and moves in the Y-axis direction while being guided by the Y-axis guide rail 131a of the column 131.

[0028] The tool spindle device 133 is mounted on the saddle 132 and moves integrally with the saddle 132 in the Y-axis direction. The tool spindle device 133 rotatably holds the machining tool 10. The tool spindle device 133 comprises a housing 133a, a tool spindle 133b, a tool motor 134 that rotationally drives the tool spindle 133b, and an encoder 135 (see Figure 2) that detects the rotation angle of the tool motor 134.

[0029] The housing 133a of the tool spindle unit 133 is fixed to the saddle 132, and the tool spindle 133b of the tool spindle unit 133 is rotatably supported by the housing 133a. A machining tool 10 is attached to the tool spindle 133b. The tool motor 134 is a servo motor controlled by the control unit 140. The tool spindle unit 133 makes the machining tool 10 rotatable around the Ct axis by the drive of the tool motor 134. In this way, the tool holder 130 holds the machining tool 10 so that it can move in the Y-axis and Z-axis directions relative to the bed 110, and so that it can rotate around the Ct axis.

[0030] The control unit 140 is equipped with a processor (arithmetic processing unit) and a memory device, and controls the drive unit by executing a machining program. In other words, the control unit 140 controls the rotation of the machining tool 10 along the Ct axis, the rotation of the workpiece W along the Cw axis, and the relative movement between the workpiece W and the machining tool 10.

[0031] In detail, the control unit 140 positions the rotation axis Zt of the machining tool 10 so that it has an axial intersection angle α with respect to the rotation axis Zw of the workpiece W. In this embodiment 1, the control unit 140 rotates the B-axis rotary table 122 to position the workpiece W and the machining tool 10 so that they have an axial intersection angle α. The configuration of the control unit 140 will be described in detail later.

[0032] The tool phase detection unit 126 detects the phase of the machining tool 10 when the workpiece W is attached to the workpiece spindle device 123. The phase of the machining tool 10 is the angle between a reference plane passing through the central axis of the machining tool 10 and the reference position Pt, and a plane passing through a point on the outer surface of the machining tool 10 that is different from the reference position Pt and the central axis of the machining tool 10, with a specific position on the outer surface of the machining tool 10 as the reference point.

[0033] The tool phase detection unit 126 may be a contact type that detects the phase of the machining tool 10 while in contact with the outer surface of the machining tool 10, or it may be a non-contact type that detects the phase of the machining tool 10 without contact with the outer surface of the machining tool 10 by using a laser beam or the like. The tool phase detection unit 126 transmits the detected phase of the machining tool 10 to the steady-state position deviation calculation unit 145, which will be described later.

[0034] The workpiece phase detection unit 136 is provided, for example, on the saddle 132. The workpiece phase detection unit 136 is a sensor capable of detecting the distance to the teeth on the workpiece W when the workpiece spindle 123b is holding the workpiece W and the workpiece W is rotating. The workpiece phase detection unit 136 preferably uses a non-contact distance sensor, such as an eddy current or a laser. However, it is also possible to use a contact-type sensor for the workpiece phase detection unit 136. Since the workpiece phase detection unit 136 is provided on the saddle 132, it moves together with the tool spindle 133b. Furthermore, the workpiece phase detection unit 136 may be provided so that the detection unit can move forward and backward.

[0035] The phase of the workpiece W is defined as the angle between a reference plane passing through the central axis of the workpiece W and the reference position Pt, and a plane passing through a point on the outer surface of the workpiece W that is different from the reference position and the central axis of the workpiece W, with a specific position on the outer surface of the workpiece W as the reference point. The workpiece phase detection unit 136 may be a contact type that detects the phase of the workpiece W while in contact with the outer surface of the workpiece W, or a non-contact type that detects the phase of the workpiece W without contact with the outer surface of the workpiece W by using a laser beam or the like. The workpiece phase detection unit 136 transmits the detected phase of the workpiece W to the steady-state position deviation calculation unit 145, which will be described later.

[0036] However, both or one of the tool phase detection unit 126 and the workpiece phase detection unit 136 may be omitted.

[0037] 2. Configuration of the machining tool 10 The processing apparatus 101 is used to create gears in a workpiece W using a processing tool 10. For this reason, the processing tool 10 in this embodiment 1 includes the first cutting edge tool 10A shown in Figure 3. Other processing tools that can be replaced with the first cutting edge tool 10A include, for example, hobs, gear grinding wheels, shaper cutters, end mills, milling tools, drills, taps, chamfering tools, turning tools, threading tools, and grinding tools.

[0038] As shown in Figure 3, the first cutting tool 10A is called a "gear skiving cutter" or "skiving tool," and comprises a tool body 11A that is rotationally driven around a rotation axis Zt, and a plurality of cutting edges 12A provided on the outer circumference of the tool body 11A in the circumferential direction D. Each cutting edge 12A is formed in a convex shape. Each cutting edge 12 has a rake face 13 which is the tip side surface in its extending direction, a front relief face 14 which is its radially outer surface, and a side relief face 15 which is its circumferential outer surface. All of the plurality of cutting edges 12A have the same helix angle with respect to the rotation axis Zt (they may not have a helix angle).

[0039] The machining process that creates gears in a workpiece W using a first cutting tool 10A is called "gear skiving." In this gear skiving process, the first cutting tool 10A is cantilevered to the tool spindle 133b of the tool spindle device 133. In this gear skiving process, the rotation axis Zt of the first cutting tool 10A is tilted at an axis intersection angle α with respect to the rotation axis Zw of the workpiece W (see Figure 1), and the workpiece W and the first cutting tool 10A are rotated synchronously while the first cutting tool 10A is repeatedly operated at a predetermined feed rate in the tool feed direction. In the case of the first cutting tool 10A, the axis intersection angle α of the rotation axis Zt with respect to the rotation axis Zw of the workpiece W is set to approximately 20°.

[0040] 3. Configuration of the control unit 140 As shown in Figure 2, the control unit 140 includes a first control unit 141, a second control unit 142, a storage unit 143, a steady-state position deviation calculation unit 145, and a rotation start phase determination unit 146.

[0041] The first control unit 141 includes a workpiece position command unit 141a for the workpiece motor 124 and a tool position command unit 141b for the tool motor 134. The workpiece position command unit 141a and the tool position command unit 141b perform a synchronous phase calculation when the conditions for synchronization are met. The second control unit 142 includes a position control processing unit 142a, a speed control processing unit 142b, and a current control processing unit 142c for the workpiece motor 124. The second control unit 142 also includes a position control processing unit 142d, a speed control processing unit 142e, and a current control processing unit 142f for the tool motor 134.

[0042] The first control unit 141 and the second control unit 142 function as a CNC (Computerized Numerical Control) device. In the first control unit 141, control commands for the workpiece motor 124 are generated (calculated) by the workpiece position command unit 141a, and control commands for the tool motor 134 are generated (calculated) by the tool position command unit 141b. The NC program includes a dedicated G-code. The type of machining can be determined from this G-code.

[0043] Furthermore, the first control unit 141 and the second control unit 142 also function as servo amplifiers and are configured to include at least one of the following: proportional control (P control), proportional-integral control (PI control), proportional-derivative control (PD control), and proportional-integral-derivative control (PID control).

[0044] The first control unit 141 and the second control unit 142 may be a single control unit, or they may be separate control units connected by a communication cable. Furthermore, the workpiece position command unit 141a and the tool position command unit 141b may be separate control devices, or they may be a single integrated control device.

[0045] The position control processing unit 142a includes a counter 144a. The counter 144a receives the detected rotational position detected by the encoder 125 and the rotational position command of the workpiece motor 124. The counter 144a calculates the difference between the rotational position command and the detected rotational position as the position deviation amount of the workpiece W.

[0046] The position control processing unit 142d includes a counter 144b. The counter 144b receives the detected rotational position detected by the encoder 135 and the rotational position command of the tool motor 134. The counter 144b calculates the difference between the rotational position command and the detected rotational position as the position deviation amount of the machining tool 10.

[0047] The memory unit 143 stores gain parameter table data (not shown) in which the gain parameters of each motor corresponding to the machining conditions are set for each type of machining. Therefore, the gain parameters of the workpiece motor 124 for each type of machining and the gain parameters of the tool motor 134 for each type of machining are stored in the memory unit 143. The gain parameters stored in the memory unit 143 include at least the proportional gain (P gain) parameter. These gain parameters may further include at least one of the integral gain (I gain) and differential gain (D gain) parameters. In this embodiment 1, the memory unit 143 stores the position loop gain Gw of the workpiece motor 124 and the position loop gain Gt of the tool motor 134. The position control processing unit 142a acquires the position loop gain Gw of the workpiece motor 124 stored in the memory unit 143. The position control processing unit 142d acquires the position loop gain Gt of the tool motor 134 stored in the memory unit 143.

[0048] The memory unit 143 stores the workpiece rotation speed Vw when the workpiece motor 124 is rotating at a steady rate, and the tool rotation speed Vt when the tool motor 134 is rotating at a steady rate. The memory unit 143 may also store the encoder resolution of the encoder 125 of the workpiece motor 124, or the encoder resolution of the encoder 135 of the tool motor 134. The memory unit 143 may also store the electronic gear, which is the amount of movement per pulse, for either the workpiece motor 124 or the tool motor 134.

[0049] The workpiece position command unit 141a reads the rotation position command for the workpiece motor 124 written in the NC program and inputs it to the position control processing unit 142a. The position control processing unit 142a calculates the difference between the rotation position command of the workpiece motor 124 and the detected rotation position detected by the encoder 125, i.e., the position deviation amount. Based on the position deviation amount and the position loop gain Gw of the workpiece motor 124, the position control processing unit 142a calculates a speed command and inputs it to the speed control processing unit 142b. Based on the speed command calculated by the position control processing unit 142a, the speed control processing unit 142b calculates a current command and inputs it to the current control processing unit 142c. Based on the current command calculated by the speed control processing unit 142b, the current control processing unit 142c controls the rotation of the workpiece motor 124.

[0050] The tool position command unit 141b reads the rotation position command for the tool motor 134 written in the NC program and inputs it to the position control processing unit 142d. The position control processing unit 142d calculates the difference between the rotation position command of the tool motor 134 and the detected rotation position detected by the encoder 135, i.e., the position deviation amount. Based on the position deviation amount and the position loop gain Gt of the tool motor 134, the position control processing unit 142d calculates a speed command and inputs it to the speed control processing unit 142e. Based on the speed command calculated by the position control processing unit 142d, the speed control processing unit 142e calculates a current command and inputs it to the current control processing unit 142f. Based on the current command calculated by the speed control processing unit 142e, the current control processing unit 142f controls the rotation of the tool motor 134.

[0051] The steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dw of the workpiece W when the workpiece W is attached to the workpiece spindle 123b and rotated at a constant workpiece rotation speed Vw. Specifically, the steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dw related to the workpiece motor 124 using the following equation (1), based on the workpiece rotation speed Vw and the position loop gain Gw of the workpiece motor 124 stored in the storage unit 143.

[0052]

number

[0053] The coefficient Aw is an arbitrary constant. By appropriately setting the coefficient Aw, the steady-state position deviation Dw of the workpiece W can be applied to any processing device 101. For example, if the steady-state position deviation Dw is a value per pulse, setting Aw to 360 allows the steady-state position deviation Dw to be converted to a value per degree.

[0054] Furthermore, Aw may also be configured to include encoder resolution and electronic gear ratio. This makes it easy to correlate the encoder resolution, which is the number of divisions per motor rotation (360°), with the electronic gear ratio, which relates to the resolution per pulse.

[0055] Furthermore, the steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dt of the machining tool 10 when the machining tool 10 is attached to the tool spindle 133b and rotated at a constant tool rotation speed Vt. Specifically, the steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dt related to the tool motor 134 using the following equation (2), based on the tool rotation speed Vt and the position loop gain Gt of the tool motor 134 stored in the storage unit 143.

[0056]

number

[0057] The coefficient At is an arbitrary constant. By setting the coefficient At appropriately, the steady-state position deviation of the workpiece can be applied to any machining device. For example, if the steady-state position deviation is a value per pulse, setting At to 360 allows the steady-state position deviation to be converted to a value per degree.

[0058] Furthermore, At may be configured to include encoder resolution and electronic gear ratio. This makes it easy to correlate the encoder resolution, which is the number of divisions per motor rotation (360°), with the electronic gear ratio, which relates to the resolution per pulse.

[0059] The rotation start phase determination unit 146 determines at least one of the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W based on the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

[0060] The rotation start phase determination unit 146 may determine both the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W. In this case, the rotation start phase determination unit 146 may be configured to determine the rotation start phase of the machining tool 10 so as to make the steady position deviation Dt of the machining tool 10 zero, and to determine the rotation start phase of the workpiece W so as to make the steady position deviation Dw of the workpiece W zero. This makes it possible to make the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W zero. Furthermore, since the steady position deviations Dt and Dw of the machining tool 10 and the workpiece W can be made zero, the machining accuracy of the workpiece W can be improved.

[0061] Furthermore, the rotation start phase determination unit 146 may be configured to make the difference ΔD between the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W zero by determining both the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W. In this case, the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W do not have to be zero.

[0062] Alternatively, the rotation start phase determination unit 146 may be configured to make the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W zero by determining only one of the rotation start phases of the machining tool 10 and the workpiece W.

[0063] The initial state is defined as the state in which the machining tool 10 and the workpiece W are not rotating, and the reference position Pt of the machining tool 10 and the reference position Pw of the workpiece W are in corresponding phases. The rotation start phase determination unit 146 determines at least one of the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W such that the reference position Pr of the machining tool 10 corresponding to the reference position Pw of the workpiece W and the reference position Pt of the machining tool 10 have a displacement amount corresponding to the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W. The following will be explained with reference to Figures 4 and 5.

[0064] Figure 4 shows the relationship between the deviations of the workpiece motor 124 and the tool motor 134 and the elapsed time, with the time when the command to start rotation is issued to the workpiece motor 124 and the tool motor 134 being set to 0. As shown in Figure 4, when the workpiece W is rotated by the workpiece motor 124, in region a, the deviation of the workpiece motor 124 increases with the passage of time. Region a is the region in which the rotational speed of the workpiece motor 124 increases with time. In region b, the deviation of the workpiece motor 124 becomes the steady-state position deviation Dw. Region b is the region in which the workpiece motor 124 rotates at a constant rotational speed Vw.

[0065] On the other hand, when the machining tool 10 is rotated by the tool motor 134, in region a, the deviation of the tool motor 134 increases with time. Region a is the region in which the rotational speed of the tool motor 134 increases with time. In region b, the deviation of the tool motor 134 becomes the steady-state position deviation Dt. Region b is the region in which the tool motor 134 rotates at a constant rotational speed Vw.

[0066] Both the workpiece motor 124 and the tool motor 134 take time to reach a constant rotational speed. Therefore, when both the workpiece motor 124 and the tool motor 134 are rotating at constant rotational speeds Vt and Vw (region b), a steady-state position deviation Dw occurs for the workpiece W and a steady-state position deviation Dt occurs for the machining tool 10. The difference ΔD between the steady-state position deviation Dw of the workpiece W and the steady-state position deviation Dt of the machining tool 10 persists even in region b where the rotational speeds of the workpiece W and the machining tool 10 have become constant.

[0067] Therefore, in this embodiment 1, as shown in Figure 5(a), the initial state is defined as a state in which the machining tool 10 and the workpiece W are not rotating, and the reference position Pt of the machining tool 10 and the reference position Pw of the workpiece W are in corresponding phases.

[0068] Next, the rotation start phase determination unit 146 sets a reference position Pr corresponding to the reference position Pw of the workpiece W on the machining tool 10, as shown in Figure 5(b). The rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W are determined such that the reference position Pr and the reference position Pt of the machining tool 10 have a displacement amount corresponding to the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

[0069] Furthermore, the rotation start phase determination unit 146 determines the rotation start phase of the machining tool 10 so that the rotation start phase of the machining tool 10 advances the phase of the reference position Pt of the machining tool 10, or determines the rotation start phase of the workpiece W so that the rotation start phase of the workpiece W advances the phase of the reference position Pw of the workpiece W. In this embodiment 1, the rotation start phase determination unit 146 determines the rotation start phases of the machining tool 10 and the workpiece W so that the rotation start phases of the machining tool 10 and the workpiece W advance the phases of the reference positions Pt and Pw. The following will be explained with reference to Figures 6 and 7.

[0070] Figure 6(a) shows the time change of the phase of the reference position Pt of the machining tool 10 when the machining tool 10 and the workpiece W are rotated simultaneously after being positioned so that the reference position Pt of the machining tool 10 and the reference position Pw of the workpiece W are in corresponding phases in the initial state. Figure 6(b) shows the time change of the phase of the reference position Pw of the workpiece W in the above state.

[0071] In Figure 6(a), the solid line represents the command position for the machining tool 10 transmitted from the control unit 140, and the dashed line represents the actual position of the machining tool 10. Similarly, in Figure 6(b), the solid line represents the command position for the workpiece W transmitted from the control unit 140, and the dashed line represents the actual position of the workpiece W.

[0072] Time t in Figure 6(a) 1-3 The command position of the machining tool 10 in Figure 6(b), and time t 2-2 The commanded position of the workpiece W in the diagram coincides with the commanded position of the cutting edge of the machining tool 10. This means, for example, that the commanded position of the cutting edge of the workpiece W coincides with the commanded position of the tooth root.

[0073] However, in Figure 6(a), the actual position of the machining tool 10 is delayed by ΔT1 from the commanded position, time T 1-3 It is located at [location]. As a result, a steady-state position deviation Dt occurs in the machining tool 10. On the other hand, in Figure 6(b), the actual position of the workpiece W is delayed by ΔT2 from the commanded position, time T 2-2 It is located at [location]. As a result, a steady-state position deviation Dw occurs in the workpiece W. Note that, as shown in Figure 6(a), the difference between ΔT1 and ΔT2 |ΔT1-ΔT2| is denoted as ΔT.

[0074] Figure 7(a) shows the state where the rotational start position of the machining tool 10 has been advanced by θ1 from the reference position Pt. This indicates that the actual position of the machining tool 10 is at a position that has been advanced by time ΔT1 compared to the state before the θ1 advance from the reference position Pt.

[0075] Furthermore, Figure 7(b) shows the state where the phase of the rotation start position of the workpiece W has been advanced by θ2 from the reference position Pw. This indicates that the actual position of the workpiece W is at a position that has been advanced by time ΔT2 compared to the state before the θ2 advance from the reference position Pt.

[0076] In this state, time T in Figure 6(a) 1-3 -The reference position Pt of the machining tool 10 at ΔT1, and time T in Figure 6(b). 2-2 The reference position Pw of the workpiece W at -ΔT2 is in the same phase. This makes it possible to set the difference ΔD between the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W to 0.

[0077] However, the rotation start phase determination unit 146 may determine the rotation start phase of the machining tool 10 such that the rotation start phase of the machining tool 10 lags behind the phase of the reference position Pt of the machining tool 10, or it may determine the rotation start phase of the workpiece W such that the rotation start phase of the workpiece W lags behind the phase of the reference position Pw of the workpiece W.

[0078] 4. Operation of Processing Device 101 The operation of the processing apparatus 101 by the control unit 140 will be explained with reference to Figures 8 to 10.

[0079] Figure 8 shows the main operation flow of the processing device 101. When the processing device 101 is started, the rotation start phase processing is performed in step S1. Next, the motor control processing is performed in step S2. With this, the main operation flow of the processing device 101 is completed.

[0080] Next, the rotation start phase processing (S1) will be described with reference to Figure 9. When the rotation start phase processing (S1) is performed, in step S11, the phase of the machining tool 10 and the phase of the workpiece W are detected in the state in which they are assembled to the machining apparatus 101. In this step S11, the tool phase detection unit 126 detects the phase of the workpiece W in the state in which it is assembled to the workpiece spindle 123b. The workpiece phase detection unit 136 also detects the phase of the machining tool 10 in the state in which it is assembled to the tool spindle 133b.

[0081] Next, in step S12, the steady-state position deviation calculation unit 145 calculates the phase of the machining tool 10 and the phase of the workpiece W in the initial state, based on the phase of the workpiece W and the phase of the machining tool 10 in the state assembled to the workpiece spindle 123b.

[0082] Next, in step S13, the steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W. Specifically, the steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dw related to the workpiece motor 124 using the following equation (1), based on the rotational speed Vw of the workpiece motor 124 and the position loop gain Gw of the workpiece motor 124.

[0083]

number

[0084] Furthermore, the steady-state position deviation calculation unit 145 calculates the steady-state position deviation Dt related to the tool motor 134 based on the tool rotation speed Vt and the position loop gain Gt of the tool motor 134 using the following equation (2).

[0085]

number

[0086] Next, in step S14, the rotation start phase determination unit 146 calculates the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

[0087] Next, in step S15, the rotation start phase determination unit 146 determines the rotation start position of the machining tool 10 and the rotation start position of the workpiece W based on the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

[0088] Specifically, the rotation start phase determination unit 146 calculates the phase of the reference position Pt of the machining tool 10 and the phase of the reference position Pw of the workpiece W in the initial state where the machining tool 10 and the workpiece W are not rotating and the reference position Pt of the machining tool 10 and the reference position Pw of the workpiece W are in corresponding phases.

[0089] Next, the rotation start phase determination unit 146 determines the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W such that the reference position Pr of the machining tool 10 and the reference position Pt of the machining tool 10 have a displacement amount corresponding to the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

[0090] The rotation start phase determination unit 146 transmits the determined rotation start phase of the machining tool 10 to the tool position command unit 141b, and transmits the determined rotation start phase of the workpiece W to the workpiece position command unit 141a.

[0091] Next, in step S16, the phase of the machining tool 10 and the phase of the workpiece W are set to the rotation start phase. This is explained in detail below. The workpiece position command unit 141a rotates the workpiece motor 124 to set the phase of the reference position Pw of the workpiece W to the rotation start phase. The tool position command unit 141b rotates the tool motor 134 to set the phase of the reference position Pt of the machining tool 10 to the rotation start position. With this, the rotation start phase processing (S1) is completed.

[0092] Next, the motor control process (S2) will be explained with reference to Figure 10. Step S21 is the step of reading the NC program. Step S22 is the step of reading the workpiece spindle position command and the tool spindle position command from the machining program (NC program, etc.) and inputting the workpiece spindle position command and the tool spindle position command from the first control unit 141 to the second control unit 142.

[0093] Step S23 is a step in which the second control unit 142 receives input for the tool spindle detection position from the encoder 135 of the tool motor 134, and also receives input for the workpiece spindle detection position from the encoder 125 of the workpiece motor 124.

[0094] Next, in step S24, position control processing is performed. Specifically, in step S24, the position control processing units 142a and 142d calculate a speed command based on the workpiece position deviation amount and machining tool position deviation amount calculated by the counters 144a and 144b, and the position loop gains Gw and Gt, and input it to the speed control processing unit 142e.

[0095] Next, in step S25, speed control processing is performed. Specifically, in step S25, the speed control processing units 142b and 142e calculate a current command based on the speed command calculated by the position control processing units 142a and 142d and input it to the current control processing units 142c and 142f.

[0096] Next, in step S26, current control processing is performed. Specifically, in step S26, the current control processing units 142c and 142f control the rotation of the workpiece motor 124 and the tool motor 134 based on the current command calculated by the speed control processing units 142b and 142e (step S27).

[0097] In step S28, it is determined whether the NC program has finished. If the program has not finished, the process returns to step S23 and the above process is repeated. On the other hand, if the NC program has finished, the motor control process (S2) ends.

[0098] 5. Effects Next, the effects of this embodiment 1 will be described. The machining apparatus 101 of this embodiment 1 machines a workpiece W while synchronously rotating the machining tool 10 and the workpiece W. The machining apparatus 101 comprises a tool spindle 133b, a workpiece spindle 123b, a steady-state position deviation calculation unit 145, and a rotation start phase determination unit 146.

[0099] The tool spindle 133b is configured to hold the machining tool 10 and to rotate the machining tool 10. The workpiece spindle 123b is configured to hold the workpiece W and to rotate the workpiece W.

[0100] The steady-state position deviation calculation unit 145 is configured to calculate the steady-state position deviation Dt of the machining tool 10 when the machining tool 10 is mounted on the tool spindle 133b and rotated at a constant tool rotation speed Vt, and to calculate the steady-state position deviation Dw of the workpiece W when the workpiece W is mounted on the workpiece spindle 123b and rotated at a constant workpiece rotation speed Vw.

[0101] The rotation start phase determination unit 146 determines at least one of the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W based on the difference ΔD between the steady position deviation Dt of the machining tool 10 and the steady position deviation Dw of the workpiece W.

[0102] According to this embodiment 1, the operator does not need to manually adjust the machining start phase of the machining tool 10 and the workpiece W, thus reducing the effort required to adjust the machining start phase of the machining tool 10 and the workpiece W. This shortens the setup time. In addition, since the adjustment workpiece W that was used to manually adjust the machining start phase is no longer needed, the amount of workpiece W to be discarded can be reduced.

[0103] Furthermore, when the machining tool 10 and the workpiece W each have their own control systems (closed-loop control, open-loop control, etc.) and perform high-precision control or high-speed control respectively, and they are machined while being rotated in sync with each other, high-precision control or high-speed control becomes possible while maintaining the synchronized state.

[0104] Furthermore, in the case of a control system that has at least one high-precision control or high-speed control, such as gear skiving, and which performs synchronized control to maintain the synchronized state, the control unit 140 performs control to maintain the synchronized state of multiple control systems (by performing control with the rotation start phase determination unit 146, etc.), thereby enabling high-precision control and high-speed control.

[0105] In gear skiving, after performing gear cutting on the workpiece W, it may be removed from the processing device 101 for hardening, and then reattached to the processing device 101 for finishing. In this case, the processing device 101 according to this embodiment 1 is effective when adjusting the phase of the teeth of the workpiece W and the phase of the cutting edge of the processing tool 10.

[0106] Furthermore, the processing apparatus 101 according to this embodiment 1 is effective not only for heat treatment but also when a process is performed to reattach a processed workpiece W that has been removed from the processing apparatus 101 back to the processing apparatus 101.

[0107] Furthermore, the machining apparatus 101 according to this embodiment 1 is also effective for machining operations where steady-state position deviations occur during synchronous machining using multiple axes (for example, machining operations that form screw threads on a screw).

[0108] In this embodiment 1, the machining apparatus 101 defines the initial state as a state in which the machining tool 10 and the workpiece W are not rotating, and the reference position Pt of the machining tool 10 and the reference position Pw of the workpiece W are in corresponding phases. The rotation start phase determination unit 146 determines at least one of the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W such that the reference position Pr on the machining tool 10 corresponding to the reference position Pw of the workpiece W and the reference position Pt of the machining tool 10 have a displacement amount corresponding to the difference ΔD. This reduces the effort required to adjust the machining start phases of the machining tool 10 and the workpiece W.

[0109] The machining apparatus 101 of this embodiment 1 further includes at least one of a workpiece phase detection unit 136 that detects the phase of the reference position Pt of the machining tool 10, and a tool phase detection unit 126 that detects the phase of the reference position Pw of the workpiece W. This allows the phase of the reference position Pt of the machining tool 10 to be accurately detected by the workpiece phase detection unit 136, or the phase of the reference position Pw of the workpiece W to be accurately detected by the tool phase detection unit 126. This makes it possible to further improve the machining accuracy of the workpiece W.

[0110] Furthermore, by providing a tool phase detection unit 126 and a workpiece phase detection unit 136, the rotation start phase of the machining tool 10 and the workpiece W can be controlled to any desired phase. This makes it easy to engage the teeth grooves of the machining tool 10 and the workpiece w when machining intermittent gears and the like.

[0111] Furthermore, the rotation start phase determination unit 146 of this embodiment 1 determines both the rotation start phase of the machining tool 10 and the rotation start phase of the workpiece W. This reduces the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W, thereby further improving the machining accuracy of the workpiece W.

[0112] Furthermore, the rotation start phase determination unit 146 of this embodiment 1 determines the rotation start phase of the machining tool 10 such that the rotation start phase of the machining tool 10 is ahead of the phase of the reference position Pt of the machining tool 10, or determines the rotation start phase of the workpiece W such that the rotation start phase of the workpiece W is ahead of the phase of the reference position Pw of the workpiece W.

[0113] The steady-state position deviations Dt and Dw are shifted in a direction that lags the phase from the target position command. According to this embodiment 1, the rotation start position is determined so that the phase of at least one of the reference position Pt of the machining tool 10 and the reference position Pw of the workpiece W is advanced, thereby reliably reducing the steady-state position deviations Dt and Dw.

[0114] (Modification 1 of Embodiment 1) Next, with reference to Figure 11, a modified example 1 of Embodiment 1 will be described. Note that, among the reference numerals used in Modified Example 1 and subsequent examples, those that are the same as those used in the previously described embodiments represent the same components, etc., as in the previously described embodiments, unless otherwise specified.

[0115] This modified example 1 is the same as embodiment 1, except that in step S16 of Figure 9, the rotation start phase of the workpiece W is changed, while the rotation start phase of the machining tool 10 is not changed.

[0116] Referring to Figure 6(a) in conjunction with Figure 11(a), Figure 11(a) shows the state in which the phase of the rotation start position of the machining tool 10 has not been changed from the reference position Pt.

[0117] On the other hand, when referring to Figure 6(b) in conjunction with Figure 11(b), Figure 11(b) shows the state where the phase of the rotation start position of the workpiece W is advanced by θ3 from the reference position Pw. This indicates that the actual position of the workpiece W has been advanced by ΔT in Figure 6(a) compared to the state before advancing by θ3 from the reference position Pt.

[0118] As a result, time T in Figure 11(a) 1-3 The reference position Pt of the machining tool 10 and the time T in Figure 11(b) 2-2and the reference position Pw of the workpiece W at -ΔT are in the same phase. Accordingly, the difference ΔD between the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W can be set to 0.

[0119] (Modification 2 of Embodiment 1) Next, with reference to FIG. 12, Modification 2 of Embodiment 1 will be described. The present Modification 2 is the same as Embodiment 1 except that, in step S16 of FIG. 9, the rotation start position of the machining tool 10 is changed, and a configuration is adopted in which the rotation start phase of the machining tool 10 is not changed.

[0120] When referred in conjunction with FIG. 6(a), FIG. 12(a) shows a state in which the phase of the rotation start position of the machining tool 10 is delayed from the reference position Pt by θ4 from 360°. This shows a state where the actual position of the machining tool 10 in FIG. 12(a) is delayed by ΔT compared to the state before delaying by θ4 from the reference position Pt.

[0121] Further, when referred in conjunction with FIG. 6(b), FIG. 12(b) shows a state where the phase of the rotation start position of the workpiece W is not changed from the reference position Pw.

[0122] Accordingly, at time T in FIG. 12(a) 1-3 , the reference position Pt of the machining tool 10 at T+ΔT, and at time T in FIG. 12(b) 2-2 , the reference position Pw of the workpiece W at said time T are in the same phase. Accordingly, the difference ΔD between the steady-state position deviation Dt of the machining tool 10 and the steady-state position deviation Dw of the workpiece W can be set to 0.

[0123] The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the gist thereof. Description of Reference Numerals

[0124] 10: Machining tool, 101: Machining device, 123b: Workpiece spindle, 126: Tool phase detection unit, 133b: Tool spindle, 136: Workpiece phase detection unit, 145: Steady-state position deviation calculation unit, 146: Rotation start phase determination unit, Dt: Steady-state position deviation of machining tool, Dw: Steady-state position deviation of workpiece, Gt: Position loop gain of machining tool, Gw: Position loop gain of workpiece, Pr: Reference position, Pt: Reference position of machining tool, Pw: Reference position of workpiece, W: Workpiece, ΔD: Difference between steady-state position deviation of machining tool and steady-state position deviation of workpiece

Claims

1. A machining apparatus for machining a workpiece while synchronously rotating the machining tool and the workpiece, A tool spindle is configured to hold the machining tool and to rotate the machining tool, A workpiece spindle configured to hold the workpiece and rotate the workpiece, A steady-state position deviation calculation unit is configured to calculate the steady-state position deviation of the machining tool when the machining tool is mounted on the tool spindle and rotated at a constant tool rotation speed, and to calculate the steady-state position deviation of the workpiece when the workpiece is mounted on the workpiece spindle and rotated at a constant workpiece rotation speed. A machining apparatus comprising: a rotation start phase determination unit that determines at least one of the rotation start phase of the machining tool and the rotation start phase of the workpiece based on the difference between the steady position deviation of the machining tool and the steady position deviation of the workpiece.

2. The initial state is defined as the state in which the machining tool and the workpiece are not rotating, and the reference position of the machining tool and the reference position of the workpiece are in corresponding phases. The machining apparatus according to claim 1, wherein the rotation start phase determination unit determines at least one of the rotation start phase of the machining tool and the rotation start phase of the workpiece such that the reference position of the machining tool corresponding to the reference position of the workpiece and the reference position of the machining tool have a displacement amount corresponding to the difference.

3. The aforementioned processing apparatus further, A tool phase detection unit for detecting the phase of the reference position of the machining tool, and The machining apparatus according to claim 2, further comprising at least one of the workpiece phase detection units for detecting the phase of the reference position of the workpiece.

4. The rotation start phase determination unit is, A machining apparatus according to any one of claims 1 to 3, which determines both the rotation start phase of the machining tool and the rotation start phase of the workpiece.

5. The rotation start phase determination unit is, The rotation start phase of the machining tool is determined such that the rotation start phase of the machining tool advances the phase of the reference position of the machining tool, or The machining apparatus according to claim 2, wherein the rotation start phase of the workpiece is determined such that the rotation start phase of the workpiece advances the phase of the reference position of the workpiece.

6. The workpiece spindle is equipped with a workpiece motor for rotating the workpiece. The machining apparatus according to claim 1, wherein the rotation start phase determination unit calculates the steady-state position deviation of the workpiece based on the following formula (1). [Math 1] Here, Dw: Steady-state position deviation of the workpiece Vw: Rotational speed of the workpiece motor Gw: Workpiece position loop gain Aw: Coefficient related to the workpiece

7. The tool spindle is equipped with a tool motor that rotates the machining tool. The machining apparatus according to claim 1, wherein the rotation start phase determination unit calculates the steady-state position deviation of the machining tool based on the following formula (2). [Math 2] Here, Dt: Steady-state position deviation of machining tool Vt: Rotational speed of the tool motor Gt: Position loop gain of the machining tool At: Coefficient related to machining tools

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