Machining form estimator

Abstract

A machining form estimating device (50) is configured to estimate the machined shape of a workpiece (W) in a gear machining device (1) configured to perform a tooth profile generation machining operation on the workpiece (W) using a cutting tool (T), and comprises: an offset data acquisition unit (51) that acquires offset data of a machining point on the workpiece (W), a tool edge path calculation unit (52) that, in a space defined by a tooth thickness direction axis parallel to a tooth thickness direction, a tooth height direction axis parallel to a tooth height direction, and a tooth width direction axis parallel to a tooth width direction in the workpiece, calculates a tool edge path as a point cloud based on the offset data of the machining point, wherein the tool edge path is a motion path of a tool edge.which is an end of a rake face (T1a) of the cutting tool (T), an outermost edge point extraction unit (53) that extracts an outermost point (CR, CL) located deepest inside the workpiece (W) from the tool edge path, which has a plurality of values ​​of the tooth thickness direction axis at each coordinate value of the tooth width direction axis and the tooth height direction axis, and a machining form estimation unit (54) that estimates the machined shape of the workpiece (W) based on the outermost point (CR, CL) of the tool edge path.

Description

TECHNICAL AREA

[0001] The present invention relates to machining estimating devices. STATE OF THE ART

[0002] In a machining device that performs a tooth profile generation operation on a workpiece using a cutting tool, an estimation of the workpiece's machined shape is carried out. For example, in the configuration disclosed in patent document 1, machining vibrations occurring during tool rotation and captured during machining are subjected to a Fourier transform (FFT (Fast Fourier Transform), DFT (Discrete Fourier Transform)) to obtain a waveform. The waveform is analyzed, and its amplitude is compared to a threshold value to determine, based on a chatter vibration occurring during machining, whether the machined surface is acceptable, thereby estimating the machined shape.

[0003] In the configuration disclosed in patent document 2, the workpiece is represented as a volume element model (voxel model), and the shape of the tool's cutting edge is represented as a three-dimensional point cloud with small intervals. At each small rotation increment of the tool's cutting edge, an interference determination is performed between the volume elements and the group of straight lines connecting the tool's central axis and the points of the point cloud, and the amount of material removed from the workpiece is predicted.

[0004] In the configuration disclosed in patent document 3, in a Z-map method, in which the shape of the workpiece is represented by subdividing an XY plane into a grid and machining surface height information (height information of the machined surface) is added to each grid section, the machining shape of the workpiece is estimated by estimating a region to be removed by the workpiece, based on the workpiece path (workpiece trajectory) obtained by moving the workpiece along a machining path. Documents in accordance with the state of the art Patent documents Patent document 1: Japanese unexamined patent application publication no. 2021-68401 (JP 2021-68401 A) Patent document 2: Japanese unexamined patent application publication no. 2019-70916 (JP 2019-70916 A) Patent document 3: Japanese unexamined patent application publication no. 2012-14601 (JP 2012-14601 A) SUMMARY OF THE INVENTION Problem to be solved by the invention

[0005] However, in the configuration disclosed in patent document 1, the amplitude obtained through analysis does not reflect the shape of the workpiece's machined surface, such as waviness, and the estimation accuracy of the machined shape is low. In the configuration disclosed in patent document 2, it is necessary to reduce the size of the volume elements to improve the accuracy of the machined surface. In the configuration disclosed in patent document 3, it is also necessary to reduce the size of the grid sections to improve the accuracy of the machined shape. However, this increases the computational load and requires a long time to estimate the machined shape.Therefore, in mass production machining, where machining is performed continuously within a short cycle time, the estimation of the machined shape may not be completed before the subsequent machining process, making it difficult to adjust the machining conditions, etc., for the subsequent operation.

[0006] The present disclosure was made in view of these circumstances, and one object of it is to provide a machining shape estimation device capable of estimating with high accuracy and in a short time the machined shape in a machining device performing a tooth profile generation machining operation. Means to solve the problem

[0007] One embodiment of the present disclosure is a machining form estimation device comprising: an offset data acquisition unit that acquires offset data of a machining point on a workpiece in a gear machining device that performs a tooth profile generation machining operation on the workpiece using a cutting tool; a tool edge path calculation unit that calculates a tool edge path as a point cloud based on the offset data of the machining point in a space defined in the workpiece by a tooth thickness direction axis parallel to a tooth thickness direction, a tooth height direction axis parallel to a tooth height direction, and a tooth width direction axis parallel to a tooth width direction, wherein the tool edge path is a motion path of a tool edge that is an end of a rake face of the cutting tool;an outermost edge point extraction unit that extracts an outermost point located deepest within the workpiece from the tool edge path, which has a multitude of values ​​of the tooth thickness direction axis at each coordinate value of the tooth width direction axis and the tooth height direction axis; and a machining shape estimation unit that estimates a machined shape of the workpiece based on the outermost point of the tool edge path. Effects of the invention

[0008] According to the machining form estimation device as described above in this disclosure, the tool edge path is calculated based on the offset data of the machining point, and the machining form of the workpiece is calculated based on the outermost point of the tool edge path extracted from the tool edge path. Since the offset data of the machining point are influenced by vibrations occurring at the machining point during machining by the geared machining device, the tool edge path calculated from the offset data and the outermost point of the tool edge path are also influenced by these vibrations. As a result, the estimated machining form of the workpiece is also influenced by the vibrations occurring at the machining point. Therefore, it is possible to estimate the machining form of the workpiece with high accuracy.Since the workpiece geometry is still estimated based on the outermost point of the tool edge path extracted from the tool edge path, it is possible to suppress an increase in machining load compared to a case where a solid element model or a Z-map method is used. Accordingly, the workpiece geometry W can be estimated with high accuracy in a short time.

[0009] As described above, according to the embodiment described above, it is possible to provide a machining shape estimation device that is able to estimate the machined shape with high accuracy and in a short time in a gear machining device that performs a tooth profile generation machining operation. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a conceptual representation illustrating the configuration of a gear machining device equipped with a machining form estimating device according to a first embodiment. Fig. Figure 2 shows a conceptual representation of a workpiece and a gear skiving wheel during machining according to the first embodiment, as viewed from the axial direction of the workpiece. Fig. Figure 3 shows a sectional view along a line III-III in Fig. 2 is taken. Fig. Figure 4 shows a functional block diagram of the machining shape estimation device according to the first embodiment. Fig. Figure 5 shows a conceptual representation illustrating a tool edge path in an evaluation coordinate system according to the first embodiment. Fig. Figure 6 shows a conceptual representation illustrating an evaluation tool edge path in an evaluation coordinate system according to the first embodiment. Fig. Figure 7 shows a perspective concept representation of tool edge paths. Fig. Figure 8 shows a conceptual representation illustrating the outermost points of an evaluation tool edge path in an evaluation coordinate system according to the first embodiment. Fig. Figure 9 shows a flowchart illustrating an estimation of a machined shape of a workpiece and a determination of a machining quality according to the first embodiment. Fig. Figure 10 shows a representation illustrating a left flank in an estimated machined shape of a workpiece according to a first embodiment. Fig. Figure 11 shows a representation illustrating a right flank in an estimated machined form of a workpiece according to the first embodiment. Fig. Figure 12 shows a representation illustrating a tooth profile defect of a left flank in an estimated machined shape of a workpiece according to the first embodiment. Fig. Figure 13 shows a representation illustrating a tooth profile defect of a right flank in an estimated machined shape of a workpiece according to the first embodiment. Fig. Figure 14 shows a representation illustrating a flank line profile error of a left flank in an estimated machined shape of a workpiece according to the first embodiment. Fig. Figure 15 shows a representation illustrating a flank line profile error of a right flank in an estimated machined shape of a workpiece according to the first embodiment. Fig. Figure 16 shows a representation illustrating a left flank in a measured machined form of a workpiece according to the first embodiment. Fig. Figure 17 shows a representation illustrating a right flank in a measured machined form of a workpiece according to the first embodiment. Fig. Figure 18 shows a representation illustrating a tooth profile error of a left flank in a measured machined shape of a workpiece according to the first embodiment. Fig. Figure 19 shows a representation illustrating a tooth profile error of a right flank in a measured machined shape of a workpiece according to the first embodiment. Fig. Figure 20 shows a representation illustrating a flank line profile error of a left flank in a measured machined shape of a workpiece according to the first embodiment. Fig. Figure 21 shows a representation illustrating a flank line profile error of a right flank in a measured machined shape of a workpiece according to the first embodiment. Fig. Figure 22 shows a functional block diagram of a machining form estimation device according to a second embodiment. WAYS TO IMPLEMENT THE INVENTION First embodiment 1. Configuration of a gear machining device 1

[0010] A machining form estimating device 50 according to the present embodiment estimates the machined form (machining form) of a workpiece W in a gear machining device 1 that performs gear profile machining. As an example of the gear machining device 1, with reference to Fig. 1. The gear machining device 1 is described, which produces a tooth profile (gear teeth) on the workpiece W by means of a cutting tool T, while the tool T and the workpiece W are rotated and moved relative to each other. According to the present embodiment, an example is described in this respect in which the gear machining device 1 produces an internal gear on the inner rotating surface of the workpiece W.

[0011] According to the present embodiment, the gear machining device 1 is a general-purpose machining tool, such as a machining center. The machining center is configured to allow the interchangeable mounting of cutting tools and is capable of performing machining according to the mounted workpiece. Examples of the interchangeable cutting tool T include a gear skiving tool and a gear hobbing tool. When the tool is replaced with a gear skiving tool, the gear machining device 1 acts as a device that produces a tooth profile (gear teeth) on the workpiece W by gear skiving. When the tool is replaced with a gear hobbing tool, the gear machining device 1 acts as a device that produces a tooth profile (gear teeth) on the workpiece W by milling. Fig. 1. A tool changing device and a tool magazine that holds a variety of tools are not shown.

[0012] According to the present embodiment, the machining center, which serves as the gear machining device 1, is primarily configured as a horizontal machining center. However, the gear machining device 1 can also employ other configurations, such as a vertical machining center.

[0013] As it is in Fig. As shown in Figure 1, the gear machining device 1, for example, has three linear axes (X-axis, Y-axis, and Z-axis) that are orthogonal to each other as drive axes. The direction of the axis of rotation of the cutting tool T (which coincides with the axis of rotation of the tool spindle) is defined here as the Z-axis direction, and the two axes that are orthogonal to the Z-axis direction are defined here as the X-axis and the Y-axis. Fig. 1 is the horizontal direction defined as the X-axis direction, and the vertical direction is defined as the Y-axis direction.

[0014] The gear machining device 1 further comprises a rotary axis (B-axis) as a drive axis for changing the relative orientation between the workpiece B and the cutting tool T. According to the present embodiment, the B-axis is a rotary axis whose center of rotation is parallel to the Y-axis direction. The gear machining device 1 further comprises a Ct-axis, which is a rotary axis for rotating the cutting tool T, and a Cw-axis, which is a rotary axis for rotating the workpiece W. The Ct-axis is a rotary axis whose center of rotation is parallel to the Z-axis direction. The Cw-axis is also a rotary axis whose center of rotation is parallel to the Z-direction when the B-axis is set to a reference angle.

[0015] In gear machining device 1, the configuration for moving the workpiece W and the cutting tool T relative to each other can be selected as appropriate. For example, instead of the B-axis, gear machining device 1 can have an A-axis whose center of rotation is in the X-axis direction. The following description gives an example of gear machining device 1 in which the cutting tool T is linearly movable in the Y-axis and Z-axis directions, the workpiece W is linearly movable in the X-axis direction, and the workpiece W is rotatable about the B-axis.

[0016] The gear machining device 1 comprises a bed 10, a workpiece holding device 20, a tool holding device 30, and a control device 40, which together form the body of the machining device. The machining form estimating device 50, which is described later, is connected to the gear machining device 1. The components that make up the gear machining device 1 are described below.

[0017] The bed 10 is installed on an installation surface and is formed in a shape corresponding to the shape of the workpiece holding device 20, the tool holding device 30, and the like. According to the present embodiment, the bed 10 is, for example, rectangular. A pair of X-axis guide rails 11 extending in the X-axis direction and a pair of Z-axis guide rails 12 extending in the Z-axis direction are formed on the upper surface of the bed 10.

[0018] The workpiece holding device 20 holds the workpiece W such that the workpiece W is linearly movable in the X-axis direction with respect to the bed 10 and rotatable about the B-axis and the Cw-axis. The workpiece holding device 20 mainly comprises an X-axis motion table 21, a B-axis rotary table 22 and a workpiece spindle unit 23.

[0019] The X-axis motion table 21 moves in the X-axis direction while being guided along the X-axis guide rails 11 of the bed 10 by an X-axis motion device (not shown). The B-axis rotary table 22 is located on the upper surface of the X-axis motion table 21 and moves with the X-axis motion table 21 in the X-axis direction. A rotary device 44, which will be described later, is connected to the B-axis rotary table 22, and the B-axis rotary table 22 is rotatable about the B-axis via the rotary device 44.

[0020] The workpiece spindle unit 23 is mounted on the B-axis rotary table 22 and rotates with the B-axis rotary table 22 about the B-axis. The workpiece spindle unit 23 rotatably holds the workpiece W. A rotary motor (not shown) is housed within the workpiece spindle unit 23, and the workpiece spindle unit 23 enables the workpiece W to rotate about the Cw-axis by the drive of the rotary motor. In this way, the workpiece holding device 20 allows the workpiece W to move in the X-axis direction relative to the bed 10 and to rotate about the B-axis and the Cw-axis.

[0021] In particular, the workpiece spindle unit 23 comprises a workpiece-side housing 23a and a workpiece spindle 23b. The workpiece-side housing 23a of the workpiece spindle unit 23 is attached to the B-axis rotary table 22, and the workpiece spindle 23b of the workpiece spindle unit 23 is rotatably supported by the workpiece-side housing 23a. The workpiece W is mounted at a distal end of the workpiece spindle 23b. This means that the workpiece W is supported by the workpiece spindle 23b of the workpiece spindle unit 23 in a cantilevered manner.

[0022] The toolholding device 30 mainly comprises a column 31, a saddle 32, a tool spindle unit 33, and sensors 34 and 35. The column 31 moves in the Z-axis direction while being guided along the Z-axis guide rails 12 of the bed 10 by a Z-axis motion device 43, which will be described later. Y-axis guide rails 31a are formed on a surface of the column 31 that extends in the vertical direction (the left surface in ). Fig. 1) The saddle 32 is driven by a drive mechanism such as a linear motor or a ball screw mechanism, which are not shown, to move in the Y-axis direction while being guided along the XY-axis guide rails 31a of the column 31.

[0023] The tool spindle unit 33 is mounted on the saddle 32 and moves with the saddle 32 in the Y-axis direction. The tool spindle unit 33 holds the cutting tool T. A rotary motor (not shown) is housed within the tool spindle unit 33, and the tool spindle unit 33 enables the cutting tool T to rotate about the Ct-axis by the drive of the rotary motor. In this way, the tool holder 30 allows the cutting tool T to move in the Y- and Z-axis directions with respect to the bed 10 and to be held rotatably about the Ct-axis.

[0024] In particular, the tool spindle unit 33 comprises a tool spindle-side housing 33a and a tool spindle 33b. The housing of the tool spindle unit 33 is attached to the saddle 32, and the tool spindle 33b of the tool spindle unit 33 is rotatably supported by the tool spindle-side housing 33a. The cutting tool T is mounted at a distal end of the tool spindle 33b. This means that the cutting tool T is supported by the tool spindle 33b of the tool spindle unit 33 in a cantilevered manner.

[0025] The sensor 34 is provided on the tool spindle-side housing 33a of the tool spindle unit 33. According to the first embodiment, the sensor 34 is an acceleration sensor and is configured to detect vibrations of the tool spindle unit 33. Alternatively, the sensor 34 can be provided on the saddle 32. According to the present embodiment, the sensor 34 is configured to measure acceleration in the tooth thickness direction (X) and the tooth height direction (Y), which are described later.

[0026] The control device 40 has an arithmetic processing unit (a processor) and a memory unit, and executes a machining program to control each drive device. That is, the control device 40 controls the rotation of the cutting tool T, the rotation of the workpiece W, and the relative movement between the workpiece W and the cutting tool T. The control device 40 controls each drive device, which is not shown, while synchronously controlling the rotation of the workpiece spindle unit 23 and the tool spindle unit 33 to machine gear teeth on the workpiece W.

[0027] In particular, the control device 40 sets the axis of rotation Ct of the cutting tool T to an axis crossing angle (not shown) with respect to an axis parallel to the axis of rotation Cw of the workpiece W. According to the present embodiment, the control device 40 positions the workpiece W and the cutting tool T at an axis crossing angle by rotating the B-axis rotary table 22. The control device 40 then moves the cutting tool T with respect to the workpiece W in the axial direction of the workpiece W, while the workpiece W and the cutting tool T are rotated synchronously by means of a drive device (not shown). The control device 40 thus generates an internal gear tooth on the inner rotating surface of the workpiece W. 2. Configuration of a gear skiving wheel Ta as a cutting tool T

[0028] The structure of a gear skiving wheel Ta as the cutting tool T is described with reference to Fig. 2 and Fig. 3 described. The gear skiving wheel Ta is a tool for producing an internal gear tooth on the inner rotating surface of the workpiece W. The gear skiving wheel Ta is mounted on the tool spindle 33b (which is described in Fig. (as shown in Figure 1) is mounted on the tool spindle unit 33 and rotates with the tool spindle 33b. The gear skiving Ta has a plurality of cutting edges T1 and a spindle mounting section T2. ​​The gear skiving Ta is connected to the tool spindle 33b via the spindle mounting section T2.

[0029] The plurality of cutting edges T1 are formed on the outer rotating surface of the gear skiving wheel Ta (corresponding to the outer rotating surface of the cutting tool T) and are blades for machining (machining) the inner rotating surface of the workpiece W. The plurality of cutting edges T1 are arranged in the direction of rotation of the gear skiving wheel Ta. According to the present embodiment, an example is illustrated in which the plurality of cutting edges T1 are formed at equal intervals in the direction of rotation. However, the cutting edges T1 can also be formed at unequal intervals, with some cutting edges being intentionally omitted.

[0030] The cutting edges T1 can be formed with a positive or negative helix angle relative to the axis of rotation Ct of the gear skiving Ta, or they can be formed parallel to the axis (with a zero helix angle). The helix angle of the cutting edges T1 is determined based on the helix angle of the internal gears of the workpiece W and the machining conditions, such as the axis intersection angle between the axis of rotation Cw of the workpiece W and the axis of rotation Ct of the gear skiving Ta.

[0031] Each of the cutting edges T1 has a rake face T1a, defined by an axial end face of the gear skiving Ta, a primary clearance face T1b, defined by the outer circumferential surface of the gear skiving Ta, and a flank clearance face T1c, defined by a surface having a normal in the circumferential direction of the gear skiving Ta. According to the present embodiment, the rake face T1a of each cutting edge T1 is configured to have a positive rake angle. However, the rake face T1a of each cutting edge T1 can be configured to have any rake angle.

[0032] The primary clearance surface T1b of each cutting edge T1 is formed such that it is inclined with respect to the axis of rotation Ct of the gear skiving Ta, i.e., that it lies on a conical surface. This means that the primary clearance surface T1b of each cutting edge T1 has a positive primary clearance angle. However, the primary clearance surface T1b of each cutting edge T1 can alternatively be formed parallel to the axis of rotation Ct of the gear skiving Ta, i.e., that it lies on a cylindrical surface. In other words, the enveloping surface of the plurality of cutting edges T1 can be a conical surface or a cylindrical surface. The flank clearance surface T1c of each cutting edge T1 is formed such that it is inclined with respect to the flank line direction of the cutting edge T1. In other words, the flank clearance surface T1c of each cutting edge T1 has a positive flank clearance angle.

[0033] Below, in the axial direction of the gear skiving wheel Ta, is the side of the rake faces T1a of the cutting edges T1 (left side in Fig. 3) referred to as the front side, and is the side opposite the chip surfaces T1a of the cutting edges T1, (right side Fig. 3) referred to as a reverse side. 3. Gear skiving

[0034] A gear skiving operation performed using the gear skiving wheel Ta as the cutting tool T, namely a operation to produce internal gears on the inner circular surface of the workpiece W by the gear skiving wheel Ta, is described below with reference to Fig. 2 and Fig. 3 described. Under the control of the control device 40, as described in Fig. As shown in Figure 2, the axis of rotation Ct of the gear skiving Ta and the axis of rotation Cw of the workpiece W are adjusted such that they have an axis crossing angle. Furthermore, under the control of the control device 40, the gear skiving Ta is moved relative to the workpiece W in the axial direction of the workpiece W, while the workpiece W and the gear skiving Ta are rotated synchronously. In this way, internal gears are produced on the inner rotating surface of the workpiece W. 4. Configuration of the machining form estimating device 50

[0035] The in Fig. The machining form estimator 50 shown in Figure 1 estimates the machined shape (machining form) of the workpiece W, which is machined by the gear machining device 1. The machining form estimator 50 has an arithmetic machining unit and a storage unit, and, as shown in Figure 1, has a machining form estimator 50. Fig. Figure 4 shows an offset data acquisition unit 51, a tool edge path calculation unit 52, an outermost edge point extraction unit 53, a machining form estimation unit 54, an accuracy evaluation unit 55, an adjustment unit 56, a quality determination unit 57 and a fault cause estimation unit 58.

[0036] The offset data acquisition unit 51 acquires offset data of a machining point on the workpiece W when the workpiece W is machined with the cutting tool T. The machining point offset data includes dislocations caused by forced vibration or self-excited vibration during machining of the workpiece W, and dislocations due to synchronous or asynchronous runout errors during spindle rotation.

[0037] According to the present embodiment, the offset data acquisition unit 51 obtains offset data of a machining point on the workpiece W based on an acceleration of the tool spindle-side housing 33a, which is a non-rotating section of the gear machining device 1, obtained by the sensor 35 provided on the tool spindle-side housing 33a. More precisely, the acceleration of the tool spindle-side housing 33a obtained by the sensor 35 is converted into offset data of the tool spindle-side housing 33a by applying FFT. The offset data of the tool spindle-side housing 33a is then converted into offset data of the machining point using a transfer function.

[0038] The conversion of the offset data using a transfer function can be carried out according to an inverse transfer function method as described below. First, a transfer function between the tool spindle-side housing 33a and the machining point is measured beforehand by hammering. Then, the offset data of the tool spindle-side housing 33a is multiplied by the transfer function to convert it into the offset of the machining point. According to the present embodiment, the offset data of the machining point is obtained based on the acceleration of the tool spindle-side housing 33a, which is acquired by the sensor 34a provided on the tool spindle-side housing 33a.Alternatively or additionally, the offset data of the machining point can be obtained on the basis of the acceleration of the workpiece-side housing 23a, which is obtained by the sensor 35 provided on the workpiece-side housing 23a.

[0039] The tool edge path calculation unit 52 calculates the tool edge path, namely the path of movement of the tool edge that is the end of the rake face T1a of the cutting tool T, based on the offset data of the machining point. According to the present embodiment, the tool edge path is calculated for one of a plurality of tooth grooves formed in the workpiece W by the cutting tool T.

[0040] According to the present embodiment, the tool edge path calculation unit 52 calculates the tool edge path based on offset data of the machining point, which are obtained at predetermined time intervals by the offset data acquisition unit 51. The tool edge path is calculated in a space defined with respect to the workpiece by the X-axis, which is parallel to the tooth thickness direction, the Y-axis, which is parallel to the tooth height direction, and the Z-axis, which is parallel to the tooth width direction. As described in Fig. As shown in Figure 5, the tool edge path can be represented as a point cloud in a plane defined by the X-axis and the Y-axis. As shown in Figure 5, the tool edge path can be represented as a point cloud in a plane defined by the X-axis and the Y-axis. Fig. As shown in Figure 6, an evaluation coordinate system U is set up, defined by the Z-axis, which is parallel to the tooth width direction, and the Y-axis, which is parallel to the tooth height direction. The evaluation coordinate system U is based on the workpiece W, with the center of the workpiece W serving as the origin of the X and Y axes, and the end of the workpiece W serving as the origin of the Z-axis.

[0041] The workpiece W is then fixed, and the relative movement of the cutting tool T with respect to the workpiece W is calculated. The tool edge path is defined as a point cloud, and the movement of the cutting tool T is calculated at each small rotation increment of the cutting tool T, i.e., at each small time increment of the cutting tool's movement T. The offset data of the machining point is then assigned to each point on the tool edge. The sampling cycle of the offset data is configured to match the analysis cycle. If the sampling cycle of the offset data and the analysis cycle do not match, one or both can be interpolated so that the periods coincide.

[0042] The point cloud of the tool edge path, along with the associated offset data of the machining point, is then converted into grid coordinate values ​​in the evaluation coordinate system U to calculate an evaluation tool edge path. According to the present embodiment, the values ​​in the tooth height direction Y of the tool edge point cloud are converted into grid coordinate values ​​by interpolation, and then the values ​​in the tooth width direction Z are converted to the nearest grid coordinate values ​​to calculate the evaluation tool edge path.

[0043] This means that, as it says in Fig. As shown in Figure 6, for a point cloud of the tool edge path at a given analysis time, the value in the Y-axis tooth height direction of the intersection point B1 between the straight line connecting points A1 and A2 of the tool edge path and the grid line perpendicular to the Y-axis tooth height direction is used as the interpolated Y-axis value between points A1 and A2 of the tool edge path. The value in the Y-axis tooth height direction of the intersection point B2 between the straight line connecting points A2 and A3 of the tool edge path and the grid line perpendicular to the Y-axis tooth height direction is used as the interpolated Y-axis value between points A2 and A3 of the tool edge path. The Z-axis value of the grid coordinates C1 nearest to the intersection point B1 is used as the converted Z-axis value between points A1 and A2 of the tool edge.The Z-axis value of the grid coordinates C2, which are closest to the intersection point B2, is used as the converted Z-axis value between points A2 and A3 of the tool path. The point cloud of the tool path is converted in the same way to calculate the evaluation tool path including points C1 and C2.

[0044] Fig. Figure 7 illustrates, as an example, the tool edge paths after interpolation in the tooth height direction Y (before conversion in the tooth width direction Z) for a plurality of tool edge paths represented as point clouds. According to the present embodiment, the point clouds in which the interpolated points in the tooth height direction Y are located within the interior of the workpiece W are retained as the evaluation tool edge path, and the remaining point clouds are deleted before conversion in the tooth width direction Z.

[0045] The outermost edge point extraction unit 53 extracts from the tool edge path described above, which has a plurality of Y-axis values ​​at each coordinate point of the Z-axis and the Y-axis, the outermost point of the tool edge path that is located deepest inside the workpiece W. According to the present embodiment, as shown in Fig. As shown in Figure 8, in the evaluation tool path, the point furthest to the right (in the positive direction) under the point cloud forming the right edge in the X-axis / Y-axis coordinate plane V is extracted as the outermost point CR, and the point furthest to the left (in the negative direction) under the point cloud forming the left edge is extracted as the outermost point CL. The outermost points are then stored in a memory unit (not shown), and the point clouds, except for the outermost points, are deleted from the evaluation tool path.

[0046] The machining form estimation unit 54 then estimates the machined shape of the workpiece W based on the outermost points of the tool edge path. According to the present embodiment, the machining form estimation unit 54 estimates the machined shape of the workpiece W based on the outermost points CR and CL of the evaluation tool edge path, assuming that the shapes CR and CL of the outermost points of the evaluation tool edge path are transferred to the machined surface of the workpiece W by machining with the cutting tool T. According to the present embodiment, the tool edge path of the cutting edge that machines a single tooth groove of the workpiece W is calculated for the cutting tool T, and the machined shape for a tooth groove of the workpiece W is estimated.According to the present embodiment, the machining shape estimation unit 54 is configured to obtain an estimation result before machining is started on the next workpiece to be machined after the workpiece W for which the machined shape is being estimated. The estimation result provided by the machining shape estimation unit 54 can, for example, be provided as a two-dimensional cross-section of the machined surface or as a three-dimensional shape of the machined surface.

[0047] The accuracy evaluation unit 55 assesses machining accuracy by comparing the machined shape of the workpiece W, which has been predefined as an ideal machined shape, with the machined shape estimated by the machining shape estimation unit 54. For example, machining accuracy can be assessed by calculating the difference between the ideal machined shape and the machined shape as a defect. The ideal machined shape can be defined based on predefined design values ​​of the gear shape.

[0048] The adjustment unit 56 adjusts the machining settings or conditions of the gear machining device 1 based on the evaluation result from the accuracy evaluation unit 55. According to the present embodiment, the evaluation result is obtained before machining begins on the next workpiece to be machined after the workpiece W for which the machined shape is estimated, and an adjustment is performed by the adjustment unit 56. In this way, the machining settings or conditions adjusted by the adjustment unit 56 can be reflected in the machining of the next workpiece.The machining settings may include at least one of the following: position data of the cutting tool T or the workpiece W in the gear machining device 1, performance values ​​of various motion devices for moving components to predetermined positions, a magnitude of runout error of the rake face of the cutting tool T, the number of regrinding operations, the magnitude of an outer diameter runout error, tool specifications after regrinding, a tool wear magnitude, and parameters relating to a tool coating.

[0049] According to the present embodiment, the adjustment unit 56 adjusts the machining settings or machining conditions of the gear machining device 1 based on the evaluation result from the accuracy evaluation unit 55. However, the adjustment unit 56 can alternatively adjust the machining settings or machining conditions of the gear machining device 1 based on the estimation result from the machining form estimation unit 54.

[0050] The quality determination unit 57 determines, based on the evaluation result from the accuracy evaluation unit 55, whether the machining quality of the workpiece W is acceptable. For example, the quality determination can be carried out such that if the error, as the evaluation result from the accuracy evaluation unit 55, is equal to or less than a predetermined reference value, the machining quality is determined to be acceptable, and if the error exceeds the reference value, the machining quality is determined to be insufficient.

[0051] If the quality determination unit 57 determines that the machining quality of workpiece W is insufficient, the fault cause estimation unit 58 estimates the cause of the insufficient machining quality based on the machined shape of workpiece W estimated by the machining form estimation unit 54. Although the procedure for estimating the cause of the insufficient machining quality is not limited, the cause can be estimated based on a comparison result between the machined shape of workpiece W, estimated by the machining form estimation unit 54, and the ideal machined shape. 5. Estimation of the machined shape of the workpiece W and determination of the machining quality

[0052] The method for estimating the machined shape of the workpiece W in the gear machining device 1 by the machining shape estimating device 50 according to the first embodiment is described below with reference to Fig. 9 described. First, in step S1, which is described in Fig. As shown in Figure 9, during the machining of the workpiece W by the gear machining device 1, the acceleration of the tool spindle-side housing 33a is measured by the sensor 34. Then, in step S2, the offset data acquisition unit 51 converts the acceleration of the tool spindle-side housing 33a into offset data of a machining point on the workpiece W based on the inverse transfer function method described above.

[0053] Then, in step S3, the tool edge path calculation unit 52 calculates the evaluation tool edge path described above based on the offset data of the machining point. According to the present embodiment, for example, the dashed line representing the black dots in Fig. 6 connects, representing the evaluation tool edge path. Subsequently, in step S4, the outermost edge point extraction unit 53 extracts the outermost points of the evaluation tool edge path. According to the present embodiment, for example, the outermost points CR and CL of the in Fig. The evaluation tool edge path shown in section 6 was extracted.

[0054] Then, in step S4, which is in Fig. As shown in Figure 9, the machining form estimating unit 54 estimates the machined shape of the workpiece W. In step S5, the accuracy evaluation unit 55 calculates the machining form error (error of the machined shape), namely the error between the machined shape of the workpiece W estimated by the machining form estimating unit 54 and the ideal machined shape, and outputs it, as shown in Figure 9. Fig. Figures 10 to 15 are shown. In step S6, the quality determination unit 57 then determines whether the machining quality of workpiece W is acceptable. The processing sequence thus ends. 6. Verification test

[0055] As a verification test of the estimation of the machining form error of the workpiece W by the machining form estimator 50 according to the first embodiment, the estimation result of the machining form error for the workpiece W from the machining form estimator 50 was compared with a measured value of the machining form error, namely the error between the machined shape of the workpiece W after machining and the ideal machined shape. The estimation results of the machining form error of the workpiece W from the machining form estimator 50 according to the first embodiment are shown in Fig. Figures 10 to 15 are shown. The measured values ​​of the machining form error W of the workpiece after machining are in Fig. Shown 16 to 21.

[0056] The in Fig. The 10 to 15 estimated results of the machining form errors shown exhibit a shape very similar to the actually measured values, which are described in Fig. Figures 16 to 21 show that the machining shape estimating device 50, according to the first embodiment, provides a high estimation accuracy for the machined shape of the workpiece W. A multitude of fine strips in the Fig. 10, Fig. 11, Fig. 16 and Fig. 17, which extends parallel to each other in an oblique direction in the figures and is visible as a region with small defects, is due to self-excited vibrations caused by chatter during machining. In contrast, thick streaks extending horizontally in the figures, which are visible as both regions with small defects and regions with large defects, are due to forced vibrations caused by contact or the like between the cutting tool T and the workpiece W during machining. 7. Functions and effects

[0057] According to the machining form estimation device 50 of the present embodiment, a tool edge path is calculated based on offset data of a machining point, and the machined shape of the workpiece W is estimated based on the outermost points of the tool edge path extracted from the tool edge path. Since the offset data of the machining point are influenced by vibrations that occur at the machining point during machining by the gear machining device 1, the tool edge path calculated from the offset data and the outermost points of the tool edge path are also influenced by these vibrations. As a result, the estimated machined shape of the workpiece W is also influenced by the vibrations that occur at the machining point. It is therefore possible to estimate the machined shape of the workpiece W with high accuracy.Since the machined shape W of the workpiece is still estimated based on the outermost points extracted from the tool edge path, it is possible to suppress an increase in computational load compared to a case where a voxel model (solid element model) or a Z-mapping method is used. Accordingly, the machined shape W of the workpiece can be estimated quickly and with high accuracy.

[0058] According to the present embodiment, the outermost points of the tool edge path refer to points on the tool edge path located furthest in the positive direction of the tooth thickness X, and to points on the tool edge path located furthest in the negative direction of the tooth thickness X. This makes it possible to accurately extract the outermost points of the tool edge path on the right and left sides (the positive and negative sides) of the rake face T1a of the cutting tool T.

[0059] The present embodiment includes the accuracy evaluation unit 55, which assesses machining accuracy by comparing a predetermined machined shape of the workpiece W with the estimate from the machining shape estimation unit 54. It is therefore possible to accurately determine the machining accuracy of the estimated machined shape.

[0060] The present embodiment also includes the adjustment unit 56, which adjusts the machining settings or machining conditions of the gear machining device 1 based on the evaluation result from the accuracy evaluation unit 55. It is therefore possible to improve the machining accuracy of the workpiece W by the gear machining device 1.

[0061] According to the present embodiment, the adjustment unit 56 adjusts the machining settings or machining conditions of the gear machining device 1 based on the evaluation result from the accuracy evaluation unit 55. However, the adjustment unit 56 can alternatively adjust the machining settings or machining conditions of the gear machining device 1 based on the estimation result from the machining form estimation unit 54. Even in this case, it is possible to improve the machining accuracy of the workpiece W by the gear machining device 1.

[0062] The present embodiment further includes the quality determination unit 57, which determines, based on the evaluation result from the accuracy evaluation unit 55, whether the machining quality of the workpiece W is acceptable, and the fault cause estimation unit 58, which estimates the cause of insufficient machining quality based on the machined shape of the workpiece W, estimated by the machining shape estimation unit 54, if the quality determination unit 57 determines that the machining quality of the workpiece W is insufficient. It is therefore possible to easily determine with high accuracy whether the machining quality of the workpiece W is acceptable.

[0063] According to the present embodiment, the machining form estimation unit 54 receives the estimation result before machining is started on the next workpiece W, which is to be machined after the workpiece W for which the machined form is estimated. Accordingly, the machining quality of the next workpiece W can be further improved by adjusting the machining conditions, etc., using the estimation result.

[0064] According to the present embodiment, the offset data acquisition unit 51 acquires an acceleration of the tool spindle-side housing 33a, which serves as a non-rotating section of the gear machining device 1, converts the acquired acceleration into offset data of the non-rotating section, and further converts the offset data of the non-rotating section into offset data of a machining point using a transfer function. As a result, offset data of the machining point, which is difficult to measure directly, can be obtained with high accuracy.

[0065] According to the present embodiment, the offset data acquisition unit 51 obtains offset data at predetermined time intervals (at each turning increment or rotation increment of the cutting tool T). The tool edge path calculation unit calculates a tool edge path based on the offset data of the machining point, which is obtained at each predetermined time. The tool edge path calculation unit converts the tool edge path into grid coordinate values ​​using the evaluation coordinate system U, which is formed by unit grids including a Y-axis parallel to the tooth height direction and a Z-axis parallel to the tooth width direction in the machined shape in the workpiece W, thereby calculating the evaluation tool edge path. The outermost edge point extraction unit 53 then extracts the outermost points of the evaluation tool edge path as the outermost points of the tool edge path.It is therefore possible to further reduce the extent of the calculation performed to determine the outermost points of the tool edge path, thus making it possible to estimate the machined shape of the workpiece W in a shorter time.

[0066] According to the present embodiment, the tool edge path calculation unit 52 converts the Y-axis values ​​of the tool edge path into grid coordinate values ​​by interpolation, and converts the Z-axis values ​​of the tool edge path into the nearest grid coordinate values, thereby calculating the evaluation tool edge path. This is suitable for calculating the evaluation tool edge path from the tool edge path shown in the evaluation coordinate system U as a shape extending upwards in the tooth height direction Y.

[0067] In addition, according to the present embodiment, the tool edge path calculation unit 52 first converts the values ​​of the Y-axis and then converts the values ​​of the Z-axis. This is suitable for calculating the evaluation tool edge path from the tool edge path shown in the evaluation coordinate system U as a shape extending in the tooth height direction Y.

[0068] According to the present embodiment, the non-rotating section that serves as a section measuring acceleration to obtain machining point offset data is the tool spindle-side housing 33a, which supports the tool spindle 33b into which the cutting tool T is mounted in the gear machining device 1. It is easier to obtain acceleration at the tool spindle-side housing 33a than at the machining point, where directly obtaining the acceleration is difficult. Therefore, it is possible to accurately obtain the machining point offset data by calculating it based on the acceleration of the tool spindle-side housing 33a, which is located close to the machining points, without directly measuring the acceleration at the machining point.

[0069] Alternatively, the non-rotating section that serves as the acceleration measurement section to obtain the machining point offset data can be the workpiece-side housing 23a, which holds the workpiece spindle 23b, carrying the workpiece W attached to it, in the gear machining device 1. Even in this case, it is possible to obtain the machining point offset data accurately by calculating the machining point offset data based on the acceleration of the workpiece-side housing 23a, which is located close to the machining point, without directly measuring the acceleration at the machining point. (Second example)

[0070] A second embodiment features a vibration prediction unit 551, as described in Fig. 22 shows, instead of the accuracy evaluation unit 55 according to the first embodiment, which is shown in Fig.Figure 4 shows that the vibration prediction unit 551 predicts the vibration behavior during the meshing of a gear pair formed by the workpiece W in which the tooth profile has been produced, based on the machined shape of the workpiece W, which is estimated by the machining shape estimation unit 54. It is therefore possible to predict the vibration behavior without evaluating the machining accuracy of the workpiece W. According to the second embodiment, the adjustment unit 56 and the quality determination unit 57 adjust the machining conditions, etc., and determine the machining quality based on the prediction results from the vibration prediction unit 551.

[0071] The second embodiment further includes a tool runout error storage unit 59, which pre-stores runout error data of distal end positions of the cutting edges caused by mounting errors of the cutting tool T. The tool edge path calculation unit 52 calculates the tool edge path based on the offset data of the machining point and the tool runout error data. The runout error of the distal end positions of the cutting edges, caused by mounting errors of the cutting tool T, cannot be measured by the accelerometer 34 (35). Therefore, the tool edge path can be measured with higher accuracy by measuring and pre-storing the tool runout error of the cutting tool T, and then calculating the tool edge path based on the offset data of the machining point and the stored tool runout error data.

[0072] The other components according to the second embodiment are the same as those according to the first embodiment described above. Therefore, these components are designated by the same reference numerals as those according to the first embodiment, and a further description is unnecessary. The second embodiment can also achieve the same effects as those according to the first embodiment.

[0073] As described above, according to the first and second embodiments, it is possible to provide the machining form estimating device 50, which is able to estimate the machined form in the gear machining device 1, which performs a tooth profile generation machining operation, with high accuracy and in a short time. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-68401

[0004] JP 2019-70916 A

[0004] JP 2012-14601

[0004]

Claims

[1] Machining shape estimator with: an offset data acquisition unit that acquires offset data of a machining point on a workpiece in a gear machining device that performs a tooth profile generation machining operation on the workpiece using a cutting tool, a tool edge path calculation unit which, in a space defined in the workpiece by a tooth thickness direction axis parallel to a tooth thickness direction, a tooth height direction axis parallel to a tooth height direction, and a tooth width direction axis parallel to a tooth width direction, calculates a tool edge path as a point cloud based on the offset data of the machining point, wherein the tool edge path is a motion path of a tool edge that is an end of a rake face of the cutting tool, an outermost edge point extraction unit that extracts an outermost point located deepest within the workpiece from the tool edge path, which has a variety of tooth thickness direction axis values ​​at each coordinate value of the tooth width direction axis and the tooth height direction axis, and a machining shape estimation unit that estimates a machined shape of the workpiece based on the outermost point of the tool edge path. [2] Machining form estimating device according to claim 1, wherein the outermost point of the tool edge path is a point located furthest in a positive direction of the tooth thickness direction in the tool edge path on a positive side in the tooth thickness direction in the tool edge path, and a point located furthest in a negative direction of the tooth thickness direction in the tooth cutting path on a negative side in the tooth thickness direction of the cutting tool. [3] Machining shape estimation device according to claim 1 or 2, further comprising an accuracy evaluation unit which evaluates machining accuracy by comparing a predetermined machining shape of the workpiece with an estimation result from the machining shape estimation unit. [4] Machining form estimation device according to claim 1 or 2, further comprising an adjustment unit which adjusts a machining setting or a machining condition of the gear machining device on the basis of an estimation result from the machining form estimation unit. [5] Machining form estimating device according to claim 3, further comprising an adjustment unit which adjusts a machining setting or a machining condition of the gear machining device on the basis of an evaluation result from the accuracy evaluation unit. [6] Machining shape estimating device according to claim 3, further comprising: a quality determination unit that determines the machining quality of the workpiece based on an evaluation result from the accuracy evaluation unit, and a fault cause estimation unit which, if the quality determination unit determines that the machining quality of the workpiece is insufficient, estimates a cause for the insufficient machining quality based on the machined shape of the workpiece, which is estimated by the machining shape estimation unit. [7] Machining shape estimation device according to claim 1 or 2, wherein the machining shape estimation unit estimates the machined shape of the workpiece before the start of machining of a subsequent workpiece which is to be machined after the workpiece for which the machined shape is estimated. [8] Machining shape estimation device according to claim 1 or 2, wherein the offset data acquisition unit acquires an acceleration of a non-rotating section of the gear machining device, converts the acquired acceleration into offset data of the non-rotating section, and converts the offset data of the non-rotating section into offset data of the machining point using a transfer function. [9] Machining shape estimating device according to claim 1 or 2, wherein The offset data procurement unit procures the offset data at predetermined time intervals. The tool edge path calculation unit calculates the tool edge path based on the offset data of the machining point, which is obtained at predetermined time intervals, and converts the tool edge path into grid coordinate values ​​in an evaluation coordinate system that has unit grids defined by tooth height direction axis grid lines parallel to the tooth height direction axis and tooth width direction axis grid lines parallel to the axis, in order to calculate an evaluation tool edge path, and The outermost edge point extraction unit extracts an outermost point of the evaluation tool edge path as the outermost point of the tool edge path. [10] Machining form estimation device according to claim 9, wherein the tool edge path calculation unit converts values ​​of the tooth height direction axis in the tool edge path into grid coordinate values ​​by interpolation, and converts values ​​of the tooth width direction axis in the tool edge path into nearest grid coordinate values ​​in order to calculate the evaluation tool edge path. [11] Machining form estimation device according to claim 10, wherein the tool edge path calculation unit converts the values ​​of the tooth height direction axis and then converts the values ​​of the tooth width direction axis. [12] Machining form estimating device according to claim 8, wherein the non-rotating section is a tool spindle-side housing that supports a tool spindle to which the cutting tool is mounted in the gear machining device. [13] Machining form estimating device according to claim 8, wherein the non-rotating section is a workpiece spindle-side housing that holds a tool spindle to which the workpiece is mounted in the gear machining device. [14] Machining shape estimation device according to claim 1 or 2, further comprising a vibration prediction unit which predicts vibration behavior during the meshing of a gear pair comprising the workpiece in which a tooth profile has been produced, on the basis of the machined shape of the workpiece which has been estimated by the machining shape estimation unit. [15] Machining form estimation device according to claim 1 or 2, further comprising a tool runout error data storage unit in which tool runout error data of the cutting tool are pre-stored, wherein the tool edge path calculation unit calculates the tool edge path on the basis of the offset data and the tool runout error data.

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