Plastic analysis device for workpieces
The workpiece plasticity analysis device addresses the inefficiencies of three-dimensional plastic analysis by approximating the workpiece in two dimensions, enhancing accuracy and reducing computational load through tool path and shape calculations, thus improving gear skiving simulation efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- JTEKT CORP
- Filing Date
- 2024-12-27
- Publication Date
- 2026-07-09
AI Technical Summary
Existing three-dimensional plastic analysis for gear skiving is computationally intensive and time-consuming, and two-dimensional approximations fail to accurately simulate tool and workpiece interactions due to fixed cutting depth and angle, leading to inaccuracies in stress field and contact state simulation.
A workpiece plasticity analysis device that performs plasticity analysis by calculating a tool path and approximating a two-dimensional shape of the workpiece, reflecting changes in rake angle and cutting depth, using a tool path calculation unit, a two-dimensional shape calculation unit, and a plasticity analysis unit to enhance accuracy and reduce computational load.
The device achieves high-accuracy plastic deformation analysis with reduced computational requirements by approximating the workpiece in two dimensions, reflecting actual tool and workpiece interactions, thereby shortening analysis time and improving simulation precision.
Smart Images
Figure 2026115185000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a workpiece plastic analysis device.
Background Art
[0002] Patent Document 1 discloses a gear machining simulation device that performs a simulation for forming a gear by performing skiving on a workpiece with a tool. Skiving is different from normal cutting in that the tool rake angle changes from positive to negative. In that regard, large loads and high temperatures act on the skiving tool, and defects and wear occur, shortening the tool life. Therefore, in order to improve the life of the gear skiving tool, it is required to grasp the influence of machining conditions and tool shape on stress, surface pressure, temperature, etc., and plastic analysis is necessary.
[0003] However, three-dimensional plastic analysis simulating skiving requires a huge amount of calculation and takes a long time, which is not practical. Therefore, Patent Document 2 discloses a configuration that performs plastic analysis by reducing the amount of calculation by approximating gear skiving to two dimensions.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, in the configuration disclosed in Patent Document 2, the tool's cutting depth and angle are not changed during the two-dimensional conversion process, and the tool is moved linearly for analysis. Therefore, the characteristics of skiving are not accurately simulated. As a result, the contact state between the tool and the workpiece, the stress field, etc., deviate significantly from the actual state, indicating room for improvement in order to enhance the accuracy of the analysis.
[0006] This invention has been made in view of the above problems, and aims to provide a workpiece plasticity analysis device that can achieve both a reduction in analysis time and an improvement in analysis accuracy. [Means for solving the problem]
[0007] One aspect of the present invention is, A workpiece plasticity analysis device that performs plasticity analysis of a workpiece when it is machined with a tool, A tool path calculation unit calculates a tool path, which is the trajectory of an arbitrary point on the edge of the cutting edge of the tool when the tool is used to machine the workpiece; A two-dimensional shape calculation unit calculates a two-dimensional shape that approximates the workpiece based on the calculation result of the tool path, A plasticity analysis unit performs plasticity analysis of the workpiece based on the calculation results of the two-dimensional shape calculation unit, It is included in the workpiece plasticity analysis equipment. [Effects of the Invention]
[0008] In the above-described workpiece plastic deformation analysis device, a two-dimensional shape approximating the workpiece's workpiece is calculated based on the tool path calculation results, and plastic deformation analysis of the workpiece is performed based on the calculated two-dimensional shape of the workpiece. As a result, the calculated tool path and the two-dimensional shape of the workpiece reflect changes in the tool's rake angle from positive to negative and changes in the depth of cut, enabling highly accurate plastic deformation analysis. Furthermore, since the plastic deformation analysis is performed based on a two-dimensional shape approximating the workpiece's workpiece, the amount of computation can be significantly reduced compared to plastic deformation analysis of a three-dimensional shape, thus shortening the analysis time.
[0009] As described above, according to the above embodiment, it is possible to provide a workpiece plasticity analysis apparatus that can achieve both a reduction in analysis time and an improvement in analysis accuracy. [Brief explanation of the drawing]
[0010] [Figure 1] A conceptual diagram showing the configuration of the workpiece plasticity analysis apparatus in Embodiment 1. [Figure 2] A diagram showing the workpiece and tool in the machining state in Embodiment 1, viewed from the axial direction of the workpiece. [Figure 3] A conceptual diagram showing one tooth groove of a workpiece being machined, viewed from a direction perpendicular to the tooth root. [Figure 4] (a) A conceptual diagram illustrating the relationship between the tool rotation speed, workpiece rotation speed, and tool feed direction in actual machining, when viewing one tooth groove of the workpiece from a direction perpendicular to the tooth root; (b) A conceptual diagram illustrating the relationship between the tool rotation speed for creating a two-dimensional plane, the workpiece rotation speed, and the tool feed direction in Embodiment 1, when viewing one tooth groove of the workpiece from a direction perpendicular to the tooth root. [Figure 5] Cross-sectional view taken along the arrow at the position of line AA in Figure 3. [Figure 6] (a) A conceptual diagram showing the positional relationship between the tool and the workpiece in a two-dimensional plane when performing plastic analysis in Embodiment 1, and (b) A diagram showing an example of the results of the plastic analysis. [Figure 7] A flowchart for performing plasticity analysis using a workpiece plasticity analysis device in Embodiment 1. [Modes for carrying out the invention]
[0011] (Embodiment 1) 1. Configuration of the workpiece plasticity analysis device 1 The workpiece plasticity analysis apparatus 1 of Embodiment 1 will be described with reference to Figure 1. The workpiece plasticity analysis device 1 is a workpiece plasticity analysis device that performs plasticity analysis of a workpiece when it is machined with a tool. As shown in Figure 1, the workpiece plasticity analysis device 1 comprises a workpiece model storage unit 11, a tool model storage unit 12, a tool trajectory calculation unit 13, a two-dimensional shape calculation unit 14, and a plasticity analysis unit 15.
[0012] The workpiece model storage unit 11 stores the model of the workpiece W after the previous machining, and the tool model storage unit 12 stores the model of the tool T. The tool T is a gear cutting tool for forming gear teeth, and skiving is performed by rotating and moving the tool T and the workpiece W relative to each other, thereby creating tooth profiles (gear teeth) on the workpiece W using the tool T. In this embodiment, an example is given of creating internal teeth on the inner surface of the workpiece W using a gear machining apparatus having a tool T. As shown in Figure 2, the gear machining apparatus having a tool T has one rotation axis (B axis) as a drive axis for changing the relative orientation between the workpiece W and the tool T. In this embodiment, the B axis is a rotation axis with a rotation center parallel to the Y axis. The gear machining apparatus also has a Ct axis as a rotation axis for rotating the tool T, and a Cw axis as a rotation axis for rotating the workpiece W. The Ct axis is a rotation axis with a rotation center parallel to the Z axis. The Cw axis is a rotation axis whose center of rotation is parallel to the Z axis direction, with the B axis as the reference angle.
[0013] The configuration for relative movement between the workpiece W and the tool T can be selected as appropriate. For example, instead of a B axis, a configuration with an A axis whose rotation center is in the X axis direction may be used. In the following, we will use as an example a gear machining apparatus in which the gear cutting tool T is capable of linear movement in the Y axis direction and the Z axis direction, 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. As shown in Figure 3, the extension direction Wb of one tooth groove Wa formed on the workpiece W by one cutting edge of the tool T is inclined with respect to the rotation center Cw of the workpiece W, and the workpiece W is a helical gear.
[0014] The gear skiving cutter as tool T is a tool for generating internal teeth on the inner peripheral surface of the workpiece W, and includes a plurality of cutting edges T1 and a spindle mounting portion T2. The tool T is mounted on the spindle of a tool spindle device (not shown) via the spindle mounting portion T2 and rotates integrally with the spindle.
[0015] The tool locus calculation unit 13 calculates a tool locus which is the locus of an arbitrary point on the ridge line of the tool edge of the tool T when machining the workpiece W with the tool T. Generally, the tool locus in three dimensions can be calculated from relational expressions shown below.
[0016]
Equation
[0017] However, in the present embodiment, in order to planarize the tool locus into a two-dimensional plane, the twist angle correction value θ βw of the workpiece (work) is set to 0, that is, as shown in Fig. 4(a), in one tooth groove Wa, the feed direction of the cutting edge of the tool T in the actual machining indicated by V coincides with the direction of the Cw axis which is the rotation axis for rotating the workpiece W. The rotational speed Tr1 of the tool T and the rotational speed Wr of the workpiece W are adjusted. In the present embodiment, as shown in Fig. 4(b), while fixing the rotational speed Wr of the workpiece W, the rotational speed Tr1 of the tool T is adjusted to the rotational speed Tr2, so that the feed direction of the cutting edge of the tool T coincides with the direction of the Cw axis. As a result, the tooth groove Wa in the workpiece W which is a helical gear can be treated as the tooth groove of a spur gear in a spur gear. As a result, in the tooth groove of a spur gear, the twist angle correction value θ βw becomes 0, so that the tool locus calculation unit 13 can calculate the tool locus in a two-dimensional plane of the r or y coordinate and the z coordinate based on the following relational expressions (1) to (5).
[0018]
Equation
[0019] In this embodiment, the tool path calculation unit 13 calculates the tool path by calculating the coordinates (y and z coordinates) of a two-dimensional plane which is a cross-section along the extending direction Wb of the tooth groove Wa of the workpiece W at an arbitrary point at the tool tip of the tool T. The calculated tool path is shown in the two-dimensional plane of the cross-section along the extending direction Wb of the tooth groove Wa as, for example, the tool path Tp1 from the previous machining and the tool path Tp2 from the current machining, as shown in Figure 5. In Figure 5, Ts represents the cutting edge at the start of the current machining, Tm represents the cutting edge during the current machining, and Te represents the cutting edge at the completion of the current machining.
[0020] The two-dimensional shape calculation unit 14 calculates a two-dimensional shape that approximates the workpiece W based on the calculation results of the tool path. As shown in Figure 5, in the cross section along the extension direction Wb of the tooth groove Wa shown in Figure 4(a), the difference between the tool path Tp1 when the cutting edge of the tool T passed through last time and the tool path Tp2 when it passed through this time represents the area removed by the current machining. Therefore, the outer edge of the two-dimensional shape of the workpiece W coincides with the current tool path Tp2. The calculated two-dimensional shape of the workpiece is stored in the workpiece model storage unit 11 for analysis during the next machining process.
[0021] The plasticity analysis unit 15 performs plasticity analysis based on the two-dimensional shape of the workpiece W calculated by the two-dimensional shape calculation unit 14. Prior to performing the plasticity analysis, the workpiece W is set to be an elastoplastic or rigid-plastic body, and the tool T is set to be a rigid body, an elastic body, or an elastoplastic body. These settings can be arbitrarily set by the user. The plasticity analysis in the plasticity analysis unit 15 can be performed by discretizing the workpiece W and tool T using methods such as the finite element method or the particle method. In this embodiment, for example, the stress generation during machining can be analyzed in a two-dimensional plane, as shown in Figure 6(b).
[0022] 2. Plasticity analysis method using workpiece plasticity analysis device 1 Next, the plasticity analysis method using the workpiece plasticity analysis apparatus 1 of Embodiment 1 will be explained with reference to the flowchart in Figure 7. First, in step S1 of Figure 7, the tool trajectory calculation unit 13 calculates the tool edge from the previous machining operation. In this embodiment, the tool trajectory calculation unit 13 calculates the tool edge from the cutting edge of the tool T stored in the tool model storage unit 12, as shown in Figure 5, in a two-dimensional plane, based on the relational expression described above.
[0023] Next, in step S2 of Figure 7, the two-dimensional shape calculation unit 14 calculates the two-dimensional shape of the workpiece from the previous machining operation based on the tool ridges from the previous machining operation. In this embodiment, since the workpiece W is an internal gear, as shown in Figure 5, the area radially outside the tool ridges from the previous machining operation is the workpiece from the previous machining operation.
[0024] Then, in step S3 of Figure 7, the tool path calculation unit 13 calculates the tool path for the current machining operation, similar to step S1. As shown in Figure 5, the tool path for the current machining operation is located radially outward from the tool ridge line of the previous machining operation.
[0025] Subsequently, in step S4 of Figure 7, the plastic analysis unit 15 sets the workpiece W to be either an elastoplastic or rigid-plastic body. Also, in step S5, the plastic analysis unit 15 sets the operation of the tool T. The initial positions of the tool T and the workpiece W are as shown in the positional relationship in Figure 6(a). Then, in step S6, the plastic analysis unit 15 sets the tool T to be a rigid body, an elastic body, or an elastoplastic body.
[0026] Subsequently, in step S7 of Figure 7, the plasticity analysis unit 15 discretizes the tool T or workpiece W. In this embodiment, as shown in Figure 6(b), the tool T or workpiece W is discretized using a finite element model divided into triangular meshes. Then, the plasticity analysis unit 15 performs a plasticity analysis based on this finite element model, and the flow is completed.
[0027] 3. Effects The following describes the effects of the workpiece plastic deformation analysis device 1 of this embodiment 1. The workpiece plastic deformation analysis device 1 calculates a two-dimensional shape that approximates the workpiece W based on the calculation results of the tool path, and performs plastic deformation analysis of the workpiece W based on the calculated two-dimensional shape of the workpiece W. As a result, the calculated tool path and the two-dimensional shape of the workpiece reflect the change from positive to negative in the rake angle of the tool T and the change in the depth of cut, so that plastic deformation analysis can be performed with high accuracy. Furthermore, since the plastic deformation analysis is performed based on a two-dimensional shape that approximates the workpiece W, the amount of calculation can be greatly reduced compared to when plastic deformation analysis is performed on a three-dimensional shape, and the analysis time can be shortened.
[0028] Furthermore, in this embodiment, the workpiece W is a gear, and the two-dimensional shape calculation unit calculates the two-dimensional shape of the cross-section along the extending direction Wb of the tooth groove Wa of the workpiece W. This makes it possible to calculate the two-dimensional shape of the workpiece W that constitutes the gear with high accuracy.
[0029] Furthermore, in this embodiment, the tool T is a rotary tool configured to machine the workpiece W while rotating it, and the two-dimensional shape calculation unit 14 calculates the two-dimensional shape by adjusting the rotational speed Tr1 of the tool T and the rotational speed Wr of the workpiece W so that they match the cutting speed V of the actual machining. As a result, even if the workpiece W is a helical gear, it is possible to calculate an approximate two-dimensional shape by treating it as the immediate teeth of a spur gear, thereby reducing the amount of calculation and further shortening the analysis time.
[0030] (Embodiment 2) Next, the workpiece plasticity analysis apparatus of Embodiment 2 will be described in detail. In the workpiece plasticity analysis apparatus 1 of Embodiment 1, the tool trajectory calculation unit 13 calculates the tool trajectory by calculating the coordinates of a two-dimensional plane which is a cross-section along the extension direction Wb of the tooth groove Wa of the workpiece W at an arbitrary point on the edge of the tool cutting edge of the tool T. However, the workpiece plasticity analysis apparatus of Embodiment 2 calculates the tool trajectory by calculating the rake angle and depth of cut of the tool cutting edge of the tool T over time. The other configurations of the workpiece plasticity analysis apparatus of Embodiment 2 are the same as those of Embodiment 1.
[0031] According to the workpiece plasticity analysis apparatus of Embodiment 2, the tool path is calculated by focusing on a single point at the cutting edge of the tool T, and the two-dimensional shape of the workpiece W can be calculated based on the tool path. In this case as well, since the tool path and the two-dimensional shape of the workpiece reflect the change from positive to negative rake angle of the tool T and the change in depth of cut, plasticity analysis can be performed with high accuracy. Furthermore, the amount of calculation can be reduced compared to plasticity analysis of three-dimensional shapes, and the analysis time can be shortened.
[0032] As described above, according to Embodiments 1 and 2, it is possible to provide a workpiece plasticity analysis apparatus 1 that can achieve both a reduction in analysis time and an improvement in analysis accuracy.
[0033] The present invention is not limited to the embodiments described above, and can be applied to various embodiments without departing from its spirit. [Explanation of Symbols]
[0034] 1 Workpiece plasticity analysis device 11. Workpiece Model Memory Unit 12 Tool Model Memory Unit 13 Tool path calculation section 14 Two-dimensional shape calculation section 15 Plasticity analysis department T-tool W Workpiece
Claims
1. A workpiece plasticity analysis device that performs plasticity analysis of a workpiece when it is machined with a tool, A tool path calculation unit calculates a tool path, which is the trajectory of an arbitrary point on the edge of the tool cutting edge of the tool when the tool is used to machine the workpiece; A two-dimensional shape calculation unit calculates a two-dimensional shape that approximates the workpiece based on the calculation results of the tool path calculation unit, A plasticity analysis unit performs plasticity analysis of the workpiece based on the calculation results of the two-dimensional shape calculation unit, A workpiece plasticity analysis device, including a machine tool.
2. The aforementioned workpiece is a gear, The tool path calculation unit calculates the tool path by calculating the coordinates of a two-dimensional plane, which is a cross-section along the extending direction of the tooth groove of the workpiece, of an arbitrary point on the edge of the tool cutting edge of the tool. The workpiece plasticity analysis apparatus according to claim 1, wherein the two-dimensional shape calculation unit calculates the two-dimensional shape in a cross-section along the extending direction of the tooth groove of the workpiece.
3. The aforementioned tool is a rotary tool, configured to machine the workpiece while rotating it. The workpiece plasticity analysis apparatus according to claim 2, wherein the two-dimensional shape calculation unit calculates the two-dimensional shape by adjusting the rotational speed of the tool and the rotational speed of the workpiece so as to match the cutting speed of the actual machining.
4. The workpiece plasticity analysis apparatus according to claim 1, wherein the tool trajectory calculation unit calculates the tool trajectory by calculating at least the rake angle and depth of cut of the tool blade over time.