Workpiece rotational runout analysis system and processing system

Abstract

To provide a workpiece rotational runout analysis system capable of calculating workpiece rotational runout with high accuracy by considering the weight of the workpiece.SOLUTION: A workpiece rotational runout analysis system analyzes rotational runout of a workpiece W in processing the workpiece W supported by workpiece support members 34, 41 by a tool. It includes a basic information acquisition part for acquiring basic information on the workpiece W, a workpiece weight deflection calculation part for calculating workpiece weight deflection Lm caused in the workpiece support members 34, 41 by the weight Mw of the workpiece W, a push-in deflection calculation part for calculating push-in deflection Lf caused in the work support members 34, 41 by push-in force FL, FR of the workpiece support members 34, 41, a workpiece rotational center calculation part for calculating a rotational center S1 of the workpiece W when the workpiece W is rotated on the basis of the workpiece weight deflection Lm, and a workpiece rotational runout analysis part for analyzing rotational runout of the workpiece W with respect to the rotational center S1 of the workpiece W when the workpiece W is rotated on the basis of the push-in deflection Lf.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a workpiece rotation runout analysis system and a machining system.

Background Art

[0002] Conventionally, various configurations have been proposed for estimating the machining result when machining a workpiece with a tool such as a grinding wheel. For example, in Patent Document 1, when grinding a workpiece with a grinding wheel, the spring constant and damping coefficient at the contact portion between the workpiece and the workpiece support member are calculated, and based on the spring constant and the damping coefficient, the contact dynamic stiffness, which is the dynamic stiffness at the contact portion, is calculated. Thus, considering the contact state between the workpiece and the workpiece support member, the contact dynamic stiffness is calculated with high accuracy, and a configuration for estimating the machining result with high accuracy using the contact dynamic stiffness is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the support state of the workpiece is affected by the weight of the workpiece, and rotational runout occurs due to the rotation of the workpiece during machining. However, in the configuration disclosed in Patent Document 1, the rotational runout of the workpiece is not considered. Therefore, in order to improve the estimation accuracy of the machining result, it is required to calculate the rotational runout of the workpiece with high accuracy.

[0005] The present invention has been made in view of such problems, and aims to provide a workpiece rotation runout analysis system capable of calculating the rotational runout of a workpiece with high accuracy considering the weight of the workpiece.

Means for Solving the Problems

[0006] One aspect of the present invention is a workpiece rotational vibration analysis system for analyzing the rotational vibration of a workpiece when machining the workpiece supported by a workpiece support member with a tool, a basic information acquisition unit that acquires basic information about the workpiece including information on the machining position in the workpiece; a workpiece weight deflection calculation unit that calculates the workpiece weight deflection generated in the workpiece support member due to the weight of the workpiece; a pushing deflection calculation unit that calculates the pushing deflection generated in the workpiece support member due to the pushing force with which the workpiece support member pushes the workpiece; a workpiece rotation center calculation unit that calculates the rotation center of the workpiece when the workpiece is rotated via the workpiece support member based on the workpiece weight deflection; a workpiece rotational vibration analysis unit that analyzes the rotational vibration of the workpiece with respect to the rotation center of the workpiece when the workpiece is rotated via the workpiece support member based on the pushing deflection; The workpiece rotational vibration analysis system is provided with:

Advantages of the Invention

[0007] The inventors of the present application have found that when rotating a workpiece supported by a workpiece support member via the workpiece support member, the workpiece rotates while the deflection of the workpiece support member due to the weight of the workpiece is maintained. Based on this, according to the above aspect, after calculating the rotation center of the workpiece based on the workpiece weight deflection generated in the workpiece support member due to the weight of the workpiece, the rotational vibration of the workpiece around the rotation center of the workpiece is analyzed based on the pushing deflection generated in the workpiece W due to the pushing force applied to the workpiece W from the workpiece support member. Thereby, the rotational vibration of the workpiece W can be calculated with high accuracy.

[0008] As described above, according to the above aspect, it is possible to provide a workpiece rotational vibration analysis system capable of calculating the rotational vibration of the workpiece with high accuracy in consideration of the weight of the workpiece.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] (Embodiment 1) 1. Configuration of the processing system 1 The machining system 1 in the first embodiment will be described with reference to FIG. 1. The machining system 1 targets a machining device that performs grinding. The machining system 1 includes a grinding machine 2 as a machining device and a processing unit 3.

[0011] The grinding machine 2 rotates the workpiece W, rotates the grinding wheel T as a tool that is a rotating body, and relatively approaches the grinding wheel T to the workpiece W in a direction intersecting the axis of the workpiece W, thereby grinding the outer peripheral surface or the inner peripheral surface of the workpiece W. As the grinding machine 2, a table traverse type grinding machine, a grinding wheel table traverse type grinding machine, etc. can be applied. Also, as the grinding machine 2, a cylindrical grinding machine, a cam grinding machine, etc. can be applied.

[0012] In this embodiment, as shown in FIG. 1, the workpiece W is, for example, a member formed in an axial shape. However, the shape of the workpiece W is not limited to an axial shape and can be any shape.

[0013] In this embodiment, the workpiece W is substantially rod-shaped and includes supported portions WR and WL located at both ends. However, the workpiece W shown in FIG. 1 is an example, and the grinding machine 2 can target workpieces having various shapes for grinding. In this embodiment, one supported portion WL is located at one axial end surface and forms a center hole into which a spindle center 34 as a workpiece support member described later is inserted. The center hole forming the supported portion WL has a conical shape along the tip shape of the spindle center 34.

[0014] Also, the other supported portion WR is located at the other axial end surface and forms a center hole into which a spindle center 34 as a workpiece support member described later is inserted. The center hole forming the supported portion WR has a conical shape along the tip shape of the spindle center 34. And in the workpiece W, the position where the grinding wheel T contacts is the machining position I.

[0015] The processing unit 3 includes a control device 3a that controls the grinding machine 2 and a machining estimation device 3b that estimates the machining result. The control device 3a can control the grinding process by controlling the grinding machine 2. The machining estimation device 3b has a contact dynamic stiffness calculation system 130 and a workpiece rotation vibration analysis system 140, which will be described later. It uses the workpiece-side dynamic stiffness (Cw, Kw) including the contact dynamic stiffness (Cwc, Kwc) calculated by the contact dynamic stiffness calculation system 130, and performs a simulation of the grinding process in consideration of the rotational vibration of the workpiece W analyzed by the workpiece rotation vibration analysis system 140, thereby performing a process of estimating the machining result on the workpiece W.

[0016] The machining estimation device 3b can function as a simulation device independent of the grinding machine 2 and the control device 3a, or can function as a simulation device that operates in conjunction with the grinding machine 2 and the control device 3a. In the former case, the machining estimation device 3b can determine optimal grinding conditions, for example, without actually grinding the workpiece W. In the latter case, the machining estimation device 3b can process in parallel with the grinding of the workpiece W by the grinding machine 2, and can, for example, correct the grinding conditions or operate to affect various controls. Further, the machining estimation device 3b can be an embedded system of the grinding machine 2 and the control device 3a.

[0017] 2. Configuration of the grinding machine 2 and the control device 3a An example of the configuration of the grinding machine 2 and the control device 3a will be described in detail with reference to FIG. 1. The grinding machine 2 is taken as an example of a table traverse type cylindrical grinding machine. That is, the grinding machine 2 is configured to move the workpiece W in the axial direction of the workpiece W and move the grinding wheel carriage T in a direction intersecting the axis of the workpiece W. Further, in the present embodiment, the case where the cylindrical outer peripheral surface of the workpiece W is ground by the grinding wheel carriage T is taken as an example.

[0018] The grinding machine 2 includes a bed 10, a table 20, a spindle device 30, a center rest device 40, and a grinding wheel base 50. The spindle device 30 and the center rest device 40 provided on the table 20 function as a workpiece support member for supporting the workpiece W. The grinding wheel base 50 functions as a tool support member for supporting the grinding wheel T. That is, the grinding machine 2 grinds the workpiece W supported by the workpiece support member with the grinding wheel T supported by the tool support member. Note that the grinding machine 2 may further include a dimension measuring device (not shown) for acquiring the outer dimensions of the workpiece W. Hereinafter, the components of the grinding machine 2 will be described in detail.

[0019] The bed 10 is installed on the installation surface. The bed 10 is formed with a longer width (length in the Z-axis direction) on the front side (the lower side in FIG. 1) in the X-axis direction and a shorter width on the back side (the upper side in FIG. 1) in the X-axis direction.

[0020] The bed 10 includes a Z-axis guide surface 11 extending in the Z-axis direction on the upper surface on the front side in the X-axis direction. Further, the bed 10 includes a Z-axis drive mechanism 12 that drives along the Z-axis guide surface 11. In the first embodiment, as an example, the Z-axis drive mechanism 12 includes a ball screw mechanism 12a and a Z-axis motor 12b. The ball screw mechanism 12a extends parallel to the Z-axis guide surface 11, and the Z-axis motor 12b drives the ball screw mechanism 12a.

[0021] To drive the Z-axis drive mechanism 12, a Z-axis drive circuit (not shown) and a Z-axis detector 12c are provided. The Z-axis drive circuit includes an amplifier circuit and drives the Z-axis motor 12b. In this embodiment, the Z-axis detector 12c is, for example, an angle detector such as an encoder, and detects the angle of the rotation axis of the Z-axis motor 12b. Note that the Z-axis drive mechanism 12 may be configured to apply a linear motor or the like instead of including the ball screw mechanism 12a.

[0022] Further, the bed 10 is provided with a guide surface 13 extending in a direction intersecting with the Z-axis direction on the upper surface on the rear side in the X-axis direction. In the present embodiment, the guide surface 13 is an X-axis guide surface extending in the X-axis direction orthogonal to the Z-axis. Further, the bed 10 is provided with an X-axis drive mechanism 14 that drives along the X-axis guide surface 13. In the present embodiment, as an example, the case where the X-axis drive mechanism 14 includes a ball screw mechanism 14a and an X-axis motor 14b is given. The ball screw mechanism 14a extends parallel to the X-axis guide surface 13, and the X-axis motor 14b drives the ball screw mechanism 14a.

[0023] To drive the X-axis drive mechanism 14, an X-axis drive circuit (not shown) and an X-axis detector 14c are provided. The X-axis drive circuit includes an amplifier circuit and drives the X-axis motor 14b. The X-axis detector 14c is, for example, an angle detector such as an encoder in the first embodiment, and detects the rotation angle of the rotation shaft of the X-axis motor 14b. Note that the X-axis drive mechanism 14 may be applied with a linear motor or the like instead of the configuration including the ball screw mechanism 14a.

[0024] The table 20 is formed in a long shape and is supported movably in the Z-axis direction (horizontal left-right direction) on the Z-axis guide surface 11 of the bed 10. Further, the table 20 is fixed to the ball nut of the Z-axis ball screw mechanism 12a and moves in the Z-axis direction by the rotational drive of the Z-axis motor 12b.

[0025] The spindle device 30 supports the workpiece W and rotationally drives the workpiece W. The spindle device 30 is disposed on one end side in the Z-axis direction on the table 20. The spindle device 30 includes a spindle housing 31, a spindle 32, a spindle motor 33, a spindle center 34, a spindle detector 35, and a spindle drive circuit (not shown).

[0026] The spindle housing 31 is fixed on the table 20. The spindle 32 is rotatably supported by the spindle housing 31 via bearings. The spindle motor 33 rotationally drives the spindle 32.

[0027] The spindle center 34 (corresponding to the support center) constitutes a workpiece support member that supports the end face of one axial end (the left end in FIG. 1) of the workpiece W. Specifically, the spindle center 34 supports the center hole on the spindle side (hereinafter also referred to as the "center hole WR") that constitutes the supported portion WR formed on the end face of one axial end of the workpiece W while pressing it in the axial direction of the workpiece W.

[0028] The spindle center 34 is fixed to the spindle 32 and is provided rotatably with respect to the spindle housing 31. However, when the spindle device 30 is provided with a rotating member such as a key (not shown), the spindle center 34 may be fixed to the spindle housing 31 and provided so as not to be rotatable with respect to the spindle housing 31. Further, the spindle device 30 may be provided with a chuck that grips the workpiece W as a workpiece support member instead of the spindle center 34. Note that the chuck is rotationally driven by being connected to the spindle 32.

[0029] The spindle detector 35 and the spindle drive circuit are provided to drive the spindle motor 33. In the first embodiment, the spindle detector 35 is, for example, an angle detector such as an encoder, and detects the rotation angle of the rotation axis of the spindle motor 33. The spindle drive circuit includes an amplifier circuit and drives the spindle motor 33.

[0030] The center drill device 40 supports the workpiece W together with the spindle device 30. The center drill device 40 is disposed on the other end side in the Z-axis direction on the table 20. The center drill device 40 is provided movably on the table 20 in the Z-axis direction. The center drill device 40 includes a center drill 41 and an adjustment mechanism 42. Note that when the grinding machine 2 grinds the inner peripheral surface of the workpiece W, the center drill device 40 is not required.

[0031] The center punch 41 (corresponding to the support center) constitutes a workpiece support member that supports the end face of the other end in the axial direction of the workpiece W (the right end in FIG. 1). Specifically, the center punch 41 supports the center hole WL on the center punch side (hereinafter also referred to as "center hole WL") that constitutes the supported portion WL formed on the end face of the other end in the axial direction of the workpiece W in a state of being pressed in the axial direction of the workpiece W. The center punch 41 may be provided so as not to rotate, or may be provided so as to be rotatable.

[0032] Also, the center punch 41 may be positioned at a fixed position with respect to the workpiece W, or may be provided so as to be operable in the axial direction of the workpiece W with respect to the workpiece W. In the latter case, the center punch 41 may be configured to be able to adjust the pushing force FR in the axial direction of the workpiece W with respect to the workpiece W. The pushing force FR can be controlled by means such as means for adjusting the spring force and means for adjusting the fluid pressure.

[0033] In the first embodiment, the center punching device 40 includes an adjustment mechanism 42. The adjustment mechanism 42 is constituted by, for example, a spring and is configured such that the center punch 41 exerts a pressing force. Here, in a state where the center punch 41 generates a pushing force FR with respect to the workpiece W, as a reaction, the spindle center 34 also exerts a pushing force FL with respect to the workpiece W. Specifically, the adjustment mechanism 42 is configured such that the center punch 41 and the spindle center 34 can adjust the pushing force in the axial direction of the workpiece W with respect to the workpiece W. That is, the adjustment mechanism 42 is configured such that the center punch 41 and the spindle center 34 can adjust the supporting force of the workpiece W. Here, the pushing forces FR and FL applied to the workpiece W by the center punch 41 and the spindle center 34 can be adjusted by an actuator or can be adjusted by an operator.

[0034] The grinding table 50 includes a grinding wheel T and rotationally drives the grinding wheel T. In addition to the grinding wheel T, the grinding table 50 includes a grinding table body 51, a grinding wheel shaft 52, a grinding wheel motor 53, and a grinding wheel drive circuit (not shown).

[0035] The grinding wheel T is formed in a disc shape. The grinding wheel T is used to grind the outer peripheral surface or the inner peripheral surface of the workpiece W. The grinding wheel T is configured by fixing a plurality of abrasive grains with a binder. As the abrasive grains, general abrasive grains formed of a ceramic material such as alumina or silicon carbide, super abrasive grains such as diamond or CBN, etc. are applied.

[0036] As the binder, there are vitrified (V), resinoid (B), rubber (R), silicate (S), shellac (E), metal (M), electrodeposited (P), magnesia cement (Mg), etc. Further, the grinding wheel T has a structure with pores and a structure without pores. Depending on the type of binder and the presence or absence of pores, the grinding wheel T may have a configuration that can be elastically deformed and a configuration that hardly elastically deforms. In the elastically deformable grinding wheel T, the elastic modulus varies depending on the type of binder, the presence or absence of pores, the porosity, etc.

[0037] The grinding wheel table body 51 is formed, for example, in a rectangular shape in plan view and is supported movably in the X-axis direction (horizontal front-rear direction) on the X-axis guide surface 13 of the bed 10. Further, the grinding wheel table body 51 is fixed to the ball screw nut of the X-axis ball screw mechanism 14a and moves in the X-axis direction by the rotational drive of the X-axis motor 14b. The grinding wheel table body 51 constitutes a tool support member that supports the grinding wheel T.

[0038] The grinding wheel shaft 52 is rotatably supported by the grinding wheel table body 51 via a bearing. The grinding wheel T is fixed to the tip of the grinding wheel shaft 52, and the grinding wheel T rotates by the rotation of the grinding wheel shaft 52. The grinding wheel motor 53 rotationally drives the grinding wheel shaft 52. As the bearing, a hydrostatic bearing, a rolling bearing, etc. are used.

[0039] The grinding wheel motor 53 transmits a rotational driving force to the grinding wheel shaft 52 via a belt, for example. However, the grinding wheel motor 53 may be arranged coaxially with the grinding wheel shaft 52. Generally, the rotational speed of the grinding wheel T driven by the grinding wheel motor 53 is higher than the rotational speed of the workpiece W driven by the spindle motor 33. The driving circuit for the grinding wheel is provided to drive the grinding wheel motor 53. The driving circuit for the grinding wheel includes an amplifier circuit and drives the grinding wheel motor 53.

[0040] The control device 3a is a CNC (Computer Numerical Control) device and a PLC (Programmable Logic Controller) device that execute machining control. That is, based on the grinding program, the control device 3a drives the Z-axis drive mechanism 12 and the X-axis drive mechanism 14 as moving devices to control the positions of the table 20 and the grinding wheel table 50. That is, the control device 3a relatively approaches and separates the workpiece W and the grinding wheel T by controlling the positions of the table 20 and the grinding wheel table 50 and the like. Further, the control device 3a controls the spindle device 30 and the grinding wheel table 50. That is, the control device 3a controls the rotation of the spindle 32 and the rotation of the grinding wheel T.

[0041] Also, when the axial pushing forces FL and FR applied to the workpiece W by the center rest 41 and the spindle center 34 can be adjusted by an actuator, the control device 3a can adjust the axial pushing forces FL and FR by controlling the actuator.

[0042] 3. Configuration of the machining estimation device 3b The configuration of the machining estimation device 3b will be described with reference to FIG. 2. The machining estimation device 3b includes a workpiece rotation runout analysis system 140, a command value acquisition unit 101, an estimation unit 102, a workpiece-side dynamic stiffness table storage unit 103, a tool-side dynamic stiffness table storage unit 104, a dynamic stiffness determination condition acquisition unit 105, a dynamic stiffness determination unit 106, a correction amount calculation unit 107, and an output unit 108.

[0043] 3-1. Workpiece rotation runout analysis system 140 As shown in FIG. 3, a workpiece rotation runout analysis system 140 includes a basic information acquisition unit 141, a workpiece weight deflection calculation unit 142, a workpiece weight bending angle calculation unit 143, a pushing-in bending load analysis unit 144, a support member total deflection calculation unit 145, a pushing-in deflection calculation unit 146, a workpiece rotation center calculation unit 147, and a workpiece rotation runout analysis unit 148.

[0044] The basic information acquisition unit 141 acquires basic information regarding the workpiece W. The basic information includes at least the weight of the workpiece W and the position information of the machining position I on the workpiece W. Further, the basic information may include the maximum support diameters dR and dL of the center holes WR and WL in the workpiece W shown in FIG. 4(a). Also, the basic information may include information regarding the shape of the workpiece W. In the present embodiment, the basic information includes the maximum support diameters dR and dL and information regarding the shape of the workpiece W together with the machining position I.

[0045] The workpiece weight deflection calculation unit 142 calculates the workpiece weight deflection Lm generated in the workpiece support members 34 and 41 due to the weight Mw of the workpiece W. The workpiece weight deflection Lm is, in an initial state where no acting force is applied to the workpiece W from the tool T, with respect to the case where the pushing forces FL and FR of the workpiece support members 34 and 41 are not considered, and when considering only the weight Mw of the workpiece W as shown in FIG. 4(b), the amount of deflection in which the workpiece support members 34 and 41 bend downward in the vertical direction.

[0046] As shown in Fig. 4(b), the workpiece weight bending angle calculation unit 143 calculates the workpiece weight bending angles θ’CL and θ’CR of the workpiece support members 34 and 41 due to the weight Mw of the workpiece W. In the present embodiment, the workpiece weight bending angle calculation unit 143 calculates the first bending angle θ’CL, which is the bending angle of the spindle center 34 at the contact portion between the center hole WL, which is one end of the workpiece W, and the spindle center 34, which is the first workpiece support member, and the second bending angle θ’CR, which is the bending angle of the center punch 41 at the contact portion between the center hole WR, which is the other end of the workpiece W, and the center punch 41, which is the second support member. The first bending angle θ’CL is the angle formed by the axis SCL of the spindle center 34 and the axis S1 of the workpiece W, and the second bending angle θ’CR is the angle formed by the axis SCR of the center punch 41 and the axis S1 of the workpiece W. Note that the axis S1 of the workpiece W is an imaginary line passing through both center holes WL and WR.

[0047] As shown in Fig. 4(c), the pushing-in bending load analysis unit 144 calculates, based on the workpiece weight bending angles θ’CL and θ’CR and the pushing-in forces FL and FR in the initial state where no acting force is applied to the workpiece W from the tool T, the bending component force F’B, which is the component force in the direction (vertically downward) of bending the workpiece W by the weight Mw of the workpiece W and the pushing-in forces FL and FR, and the bending load position I’, which is the position of the workpiece W where the bending component force F’B acts.

[0048] The bending component force F’B can be calculated as follows. First, the vertically downward component force F’L generated at the contact portion between the workpiece W and the spindle center 34 by the pushing-in force FL and the vertically downward component force F’R generated at the contact portion between the workpiece W and the center punch 41 by the pushing-in force FR are calculated by the following formulas A and B. F’L = FL × tan(θ’CL) ··· (Formula A) F’R = FR × tan(θ’CR) ··· (Formula B)

[0049] Then, the bending component force F’B generated in the workpiece W and the bending load position I’ can be calculated by the following formulas C and D. F’B = F’R + F’L ··· (Formula C) I’ = L × F’R / (F’R + F’L) ···(Equation D) In the example shown in Fig. 4(b), since the first bending angle θ’CL and the second bending angle θ’CR have the same value, the bending load position I’ is at the center point of the workpiece W. However, the bending load position I’ changes according to the first bending angle θ’CL and the second bending angle θ’CR.

[0050] As shown in Fig. 4(c), the total deflection calculation unit 145 of the support member calculates the total deflection L all generated in the workpiece support members 34 and 41 by the weight Mw of the workpiece W and the bending component force F’B. all The total deflection L

[0051] As shown in Fig. 3, the pushing-in deflection calculation unit 146 calculates the pushing-in deflection Lf generated in the workpiece support members 34 and 41 by the pushing-in forces FL and FR with which the workpiece support members 34 and 41 push in the workpiece W. The pushing-in deflection Lf, in the initial state where no acting force is applied to the workpiece W from the tool T, is expressed as the amount of deflection by which the workpiece support members 34 and 41 bend downward in the vertical direction due to the weight Mw of the workpiece W and the bending component force F’B, as shown in Fig. 4(c), without considering the pushing-in forces FL and FR of the workpiece support members 34 and 41 shown in Fig. 4(b) and considering the weight Mw of the workpiece W. In this embodiment, the pushing-in deflection Lf can be calculated from the difference between the total deflection L all of the workpiece support members 34 and 41 and the deflection due to the workpiece weight. As a result, the axis S2 of the workpiece W passing through both center holes WL and WR is located below the axis S1 of the workpiece W shown in Fig. 4(b) in the vertical direction.

[0052] The workpiece rotation center calculation unit 147 shown in FIG. 3 calculates the rotation center S1 of the workpiece W when the workpiece W is rotated via the workpiece support members 34 and 41 based on the workpiece weight deflection Lm. The rotation center S1 of the workpiece W coincides with the axis S1 of the workpiece W in a state where the weight Mw of the workpiece W is considered without considering the pushing forces FL and FR of the workpiece support members 34 and 41 shown in FIG. 4(b). That is, the workpiece W rotates with reference to the position where the workpiece support members 34 and 41 are deflected downward in the vertical direction by the amount of the workpiece weight deflection Lm due to the weight Mw of the workpiece W.

[0053] The workpiece rotation runout analysis unit 148 shown in FIG. 3 analyzes the rotation runout of the workpiece W with respect to the rotation center S1 of the workpiece W when the workpiece W is rotated via the workpiece support members 34 and 41 as shown in FIGS. 4(c) and 4(d) based on the push-in deflection Lf. That is, the rotation runout of the workpiece W is not affected by the workpiece weight deflection Lm. In FIG. 4(c), the workpiece W is in a state of being deflected downward in the vertical direction with respect to the rotation center S1, and in FIG. 4(d), the workpiece W is in a state of being deflected upward in the vertical direction with respect to the rotation center S1. Thus, the rotation runout of the workpiece W occurs in a direction away from the rotation center S1 according to the rotation phase of the workpiece W.

[0054] In the present embodiment, in order to estimate the machining result of the workpiece W, the workpiece rotation runout analysis unit 148 analyzes the rotation runout of the workpiece W at the machining position based on the push-in deflection Lf at the machining position. The push-in deflection Lf at the machining position can be calculated from the difference between the total deflection L at the workpiece support members 34 and 41 at the machining position and the workpiece weight deflection. The rotation runout of the workpiece W at the machining position, which is the analysis result by the workpiece rotation runout analysis unit 148, is output to the estimation unit 102. all and the workpiece weight deflection. The rotation runout of the workpiece W at the machining position, which is the analysis result by the workpiece rotation runout analysis unit 148, is output to the estimation unit 102.

[0055] 3-2. Command value acquisition unit 101 The command value acquisition unit 101 acquires command values for controlling the grinding machine 2 in grinding. When the machining estimation device 3b is a simulation device independent of the grinding machine 2 and the control device 3a, the command value acquisition unit 101 generates, by calculation, command values for controlling each part of the grinding machine 2 by inputting a grinding program and configuration information of the grinding machine 2. When the machining estimation device 3b functions as a simulation device that operates in conjunction with the grinding by the grinding machine 2 and the control device 3a, the command value acquisition unit 101 can directly acquire command values from the control device 3a.

[0056] 3-3. Estimation unit 102 The estimation unit 102 estimates at least one of the state of the workpiece W or the grinding wheel T, the shape of the workpiece W, the shape of the grinding wheel T, and the mechanical state of the grinding machine 2 during grinding by performing a grinding simulation using the command values acquired by the command value acquisition unit 101.

[0057] The state of the workpiece W includes, for example, the vibration state and temperature state of the workpiece W. The state of the grinding wheel T includes, for example, the vibration state and temperature state of the grinding wheel T, the grinding resistance generated for each part of the outer peripheral surface of the grinding wheel T, the sharpness of the grinding wheel T, and the state of the abrasive grains constituting the grinding wheel T. The state of the abrasive grains includes, for example, the average protrusion amount of the abrasive grains and the abrasive grain distribution. The shape of the workpiece W includes the shape in the middle stage of grinding and the shape at the end stage of grinding. The shape of the grinding wheel T includes the shape in the middle stage of grinding and the shape at the end stage of grinding. The mechanical state of the grinding machine 2 includes the vibration state and temperature state of the parts constituting the grinding machine 2.

[0058] In the present embodiment, the estimation unit 102 is taken as an example of a case where the shape of the workpiece W, the state of the workpiece W, and the mechanical state of the grinding machine 2 are the estimation targets by performing a process in which the shape of the workpiece W changes sequentially by a grinding simulation. In the present embodiment, the grinding simulation is performed on the assumption that the grinding wheel T does not deform. Note that the estimation unit 102 can also estimate the grinding resistance generated for each part of the outer peripheral surface of the grinding wheel T in addition to the above-mentioned estimation targets.

[0059] The estimation unit 102 includes an interference amount calculation unit 111, a grinding efficiency calculation unit 112, a grinding characteristic determination unit 113, and a grinding resistance calculation unit 114.

[0060] Based on the relative position between the workpiece W and the grinding wheel T, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T obtained using the command value acquired by the command value acquisition unit 101, the interference amount calculation unit 111 calculates the interference amount between the workpiece W and the grinding wheel T. The interference amount corresponds to the grinding amount in the radial direction of the workpiece W at each part in the circumferential direction of the workpiece W. In other words, the interference amount is the removal amount of the workpiece W ground by the grinding wheel T, specifically, the removal amount in the radial direction of the workpiece W at each part in the circumferential direction of the workpiece W. As shown in FIG. 5, the interference amount is the volume of the portion where the workpiece W and the grinding wheel T interfere (the hatched portion in FIG. 5: interference region).

[0061] The interference amount calculation unit 111 geometrically calculates the interference amount through arithmetic processing. Here, the interference amount calculation unit 111 stores the outer peripheral surface shape of the workpiece W and the outer peripheral surface shape of the grinding wheel T. As shown in the right part of FIG. 6, the outer peripheral surface shape of the workpiece W is represented by a plurality of radial line segment groups on polar coordinates with the rotation center Ow of the workpiece W as the origin. That is, the interference amount calculation unit 111 stores a plurality of line segment groups connecting the division points (white points in FIG. 6) on the outer peripheral surface obtained by equally dividing the workpiece W by an angle (p) and the rotation center Ow (origin) of the workpiece W as the outer peripheral surface shape of the workpiece W. The division points indicated by the white points in FIG. 6 are stored as the outer peripheral surface shape of the workpiece W before being removed by the grinding wheel T.

[0062] The interference amount calculation unit 111 determines the intersection points (black points in FIG. 6) between each line segment of the workpiece W and the line representing the outer peripheral surface shape of the grinding wheel T from the relative position (axial distance) between the workpiece W and the grinding wheel T and the outer peripheral surface shape of the grinding wheel T. The interference amount calculation unit 111 stores the determined intersection points (black points in FIG. 6) as the outer peripheral surface shape of the workpiece W after being removed by the grinding wheel T. That is, the interference amount calculation unit 111 changes the stored outer peripheral surface shape of the workpiece W.

[0063] Then, the interference amount calculation unit 111 subtracts the area of the triangle △Ow-b1-b2 formed by the origin Ow and the points b1 and b2 (the intersection points with the grinding wheel T) after removal from the area of the triangle △Ow-a1-a2 formed by the origin Ow and two adjacent points a1 and a2 among the points defining the outer peripheral surface shape of the workpiece W before removal. The area after subtraction is calculated for all adjacent points that define the outer peripheral surface shape of the workpiece W.

[0064] Then, the interference amount calculation unit 111 integrates the areas after each subtraction, and multiplies the integrated total area by the thickness of the workpiece W to calculate the interference amount (removal amount). In the above, the area of the removed portion is calculated by calculating the areas of two types of triangles and calculating the difference between the areas. In addition to this, the area of the removed portion may be calculated by directly calculating the quadrilateral a1-a2-b1-b2.

[0065] The grinding efficiency calculation unit 112 shown in FIG. 2 calculates the grinding efficiency Z' based on the interference amount calculated by the interference amount calculation unit 111. The grinding efficiency Z' calculates the interference amount per unit time, that is, the volume of the workpiece W ground by the grinding wheel T per unit time.

[0066] The grinding characteristic determination unit 113 determines the grinding characteristic kc based on the material of the workpiece W, the types of abrasive grains and binders of the grinding wheel T, and the state of the outer peripheral surface of the grinding wheel T. The state of the outer peripheral surface of the grinding wheel T is expressed using, for example, an index indicating the wear state or sharpness of the abrasive grains of the grinding wheel T. Here, the grinding characteristic determination unit 113 stores in advance the grinding characteristics in each state through experiments, analyses, etc.

[0067] The grinding resistance calculation unit 114 calculates the grinding resistance Fn in the normal direction (X-axis direction) of the outer peripheral surface of the workpiece W based on the grinding efficiency Z' and the grinding characteristic kc. The grinding resistance Fn is obtained by multiplying the grinding efficiency Z' by the grinding characteristic kc (Fn = kc × Z').

[0068] Note that the grinding characteristic kc has an approximately linear relationship such that the grinding resistance Fn in the normal direction (X-axis direction) increases as the grinding efficiency Z' increases. And the grinding characteristic kc changes when, for example, the grinding wheel T wears. For example, when the grinding wheel T wears, the grinding resistance Fn in the normal direction changes so as to increase with respect to the grinding efficiency Z'.

[0069] 3-4. Workpiece-side Dynamic Stiffness Table Storage Unit 103 The workpiece-side dynamic stiffness table storage unit 103 stores the dynamic stiffness data Cw, Kw (hereinafter referred to as workpiece-side dynamic stiffness data) regarding the workpiece W when divided into the workpiece W side and the grinding wheel T side with the machining part as the boundary. The workpiece-side dynamic stiffness table storage unit 103 includes a dynamic stiffness table storage unit 103a regarding the workpiece W, a dynamic stiffness table storage unit 103b regarding each device 20, 30, 40 constituting the workpiece support member, and a correspondence storage unit 103c for calculating the contact dynamic stiffness which is the dynamic stiffness of the contact part between the workpiece W and the workpiece support member (spindle center 34, center rest center 41).

[0070] The dynamic stiffness table storage unit 103a regarding the workpiece W stores the dynamic stiffness data Cwa, Kwa of the workpiece W (hereinafter referred to as workpiece dynamic stiffness data). The workpiece dynamic stiffness data Cwa, Kwa can be obtained, for example, by known hammering or FEM analysis on the workpiece W. When there are multiple types of workpieces W to be ground, the dynamic stiffness table storage unit 103a stores the workpiece dynamic stiffness data Cwa, Kwa for each of the multiple types of workpieces W.

[0071] The dynamic stiffness table storage unit 103b regarding each device 20, 30, 40 constituting the workpiece support member stores the dynamic stiffness data Cwb, Kwb of each device 20, 30, 40 constituting the workpiece support member (hereinafter referred to as support member dynamic stiffness data). The support member dynamic stiffness data Cwb, Kwb can be obtained by hammering or FEM analysis on each of the devices 20, 30, 40 constituting the workpiece support member.

[0072] When the grinding machine 2 can replace the apparatuses 20, 30, 40 that constitute a plurality of types of workpiece support members, the dynamic stiffness table storage unit 103b stores the support member dynamic stiffness data Cwb, Kwb for each of the apparatuses 20, 30, 40 that constitute the plurality of types of workpiece support members. Further, when the support member dynamic stiffness data Cwb, Kwb changes according to machining conditions or the like, the dynamic stiffness table storage unit 103b stores the correspondence relationship between the machining conditions or the like and the support member dynamic stiffness data Cwb, Kwb.

[0073] The correspondence relationship storage unit 103c stores the correspondence relationship for calculating the dynamic stiffness data Cwc, Kwc (hereinafter referred to as contact dynamic stiffness data) at the contact portion between the workpiece W and the workpiece support members (spindle center 34, center rest 41). And in the first embodiment, as will be described later, the correspondence relationship storage unit 103c stores the correspondence relationship between the machining position I shown in FIG. 7 and the differential bending angles ΔθL, ΔθR described later.

[0074] 3-5. Correspondence relationship between machining position I and differential bending angles ΔθL, ΔθR The correspondence relationship between the machining position I shown in FIG. 7 and the differential bending angles ΔθL, ΔθR described later will be described below using a model that does not consider the weight Mw of the workpiece W and the pushing forces FL, FR shown in FIGS. 8(a) and 8(b).

[0075] First, the initial state shown in Fig. 8(a) is the state before the grinding wheel T applies a force to the workpiece W. When the workpiece W is ground by the grinding wheel T, as shown in Fig. 8(b), a force is applied from the grinding wheel T to the machining position I of the workpiece W, causing the workpiece W to deflect so as to escape to the side opposite to the grinding wheel T. Then, both ends where the center holes WR and WL, which are the supported portions of the workpiece W, are located change so as to be inclined with respect to the axis S0 of the workpiece W in the initial state. The amount of change of one center hole WR of the workpiece W with respect to the initial state can be expressed as the angle θWR formed by the axis S0 of the workpiece W in the initial state and the axis SWR at the end where the center hole WR is located. Similarly, the amount of change of the other center hole WL of the workpiece W with respect to the initial state can be expressed as the angle θWL formed by the axis S0 of the workpiece W in the initial state and the axis SWL at the end where the center hole WL is located.

[0076] Also, as shown in Fig. 8(b), when the workpiece W is ground by the grinding wheel T, as the workpiece W deflects, the spindle center 34 and the center rest 41 as workpiece support members also deflect. As a result, the spindle center 34 and the center rest 41 also change so as to be inclined with respect to the axis S0 of the workpiece W in the initial state. The amount of change of the center rest 41 with respect to the initial state can be expressed as the angle θCR formed by the axis S0 of the workpiece W in the initial state and the axis SCR of the center rest 41 after the change. Similarly, the amount of change of the spindle center 34 with respect to the initial state can be expressed as the angle θCL formed by the axis S0 of the workpiece W in the initial state and the axis SCL of the spindle center 34 after the change.

[0077] And, as shown in Fig. 8(b), there is a deviation between the change amount θWR of the center hole WR of the workpiece W and the change amount θCR of the center rest 41. The absolute value of the deviation of the change amounts is defined as the differential bending angle ΔθR. Similarly, there is a deviation between the change amount θWL of the center hole WL of the workpiece W and the change amount θCL of the spindle center 34. The absolute value of the deviation of the change amounts is defined as the differential bending angle ΔθL.

[0078] The differential bending angles ΔθR and ΔθL change based on the machining position I, respectively. In this embodiment, the position where a pressure F of 1 N is applied to the workpiece W is defined as a virtual machining position, and the measured values of the differential bending angles ΔθR and ΔθL are obtained when the virtual machining position is moved in the axial direction from the position of one center hole WR to the position of the other center hole WL. Then, the correspondence between the machining position I shown in FIG. 7 and the differential bending angle Δθ is created. Then, as described above, the correspondence is stored in the correspondence storage unit 103c. Note that, instead of obtaining the measured values of the differential bending angles ΔθR and ΔθL to create the correspondence, the correspondence between the machining position I and the differential bending angles ΔθR and ΔθL may be created by theoretically calculating the relationship between the machining position I and the change amounts θWR, θWL, θCR, and θCL.

[0079] 3-6. Tool-side Dynamic Stiffness Table Storage Unit 104 The tool-side dynamic stiffness table storage unit 104 shown in FIG. 2 stores the dynamic stiffness data Ct, Kt (hereinafter referred to as tool-side dynamic stiffness data) regarding the grinding wheel T side when the workpiece W side and the grinding wheel T side are separated by the machining site. That is, the tool-side dynamic stiffness table storage unit 104 stores the tool-side dynamic stiffness data Ct, Kt in the grinding wheel table 50 including the grinding wheel T. The tool-side dynamic stiffness table storage unit 104 stores the tool-side dynamic stiffness data Ct, Kt for each type of grinding wheel T, for example.

[0080] Further, when the grinding wheel T is supported by a hydrostatic bearing and the pressure of the hydrostatic bearing can be controlled, the tool-side dynamic stiffness data Ct, Kt may be data that changes according to the pressure of the hydrostatic bearing. Therefore, the tool-side dynamic stiffness table storage unit 104 may store the damping coefficient Ct and the spring constant Kt according to the pressure of the hydrostatic bearing as machining conditions. When the tool-side dynamic stiffness data Ct, Kt changes according to machining conditions or the like, the tool-side dynamic stiffness table storage unit 104 stores the correspondence between the machining conditions or the like and the tool-side dynamic stiffness data Ct, Kt.

[0081] 3-7. Dynamic Stiffness Determination Condition Acquisition Unit 105 As shown in FIG. 2, the dynamic stiffness determination condition acquisition unit 105 acquires the dynamic stiffness determination conditions when performing grinding on the grinding machine 2. Specifically, the dynamic stiffness determination condition acquisition unit 105 acquires the dynamic stiffness determination conditions at the time of estimation (at the time of the process target) by the estimation unit 102. The dynamic stiffness determination conditions acquired by the dynamic stiffness determination condition acquisition unit 105 are information used by the dynamic stiffness determination unit 106 to calculate each dynamic stiffness. The acquired dynamic stiffness determination conditions are, for example, the type of workpiece W, the type of workpiece support member, the type of grinding wheel head T, the pressing force by the spindle center 34 and the center rest 41, and the like.

[0082] When the machining estimation device 3b is a simulation device independent of the grinding machine 2, the dynamic stiffness determination condition acquisition unit 105 acquires the conditions for determining the dynamic stiffness by inputting the mechanical configuration of the grinding machine 2 and the grinding program. Further, when the machining estimation device 3b functions as a simulation device that operates in conjunction with the grinding process by the grinding machine 2, the dynamic stiffness determination condition acquisition unit 105 may acquire the conditions for determining the dynamic stiffness by inputting the mechanical configuration of the grinding machine 2 and the grinding program from the control device 3a, or may directly acquire information regarding the conditions from the control device 3a of the grinding machine 2.

[0083] 3-8. Configuration of the dynamic stiffness determination unit 106 The dynamic stiffness determination unit 106 determines the dynamic stiffness data that affects the grinding process. The dynamic stiffness determination unit 106 separately determines the workpiece-side dynamic stiffness data Cw, Kw and the tool-side dynamic stiffness data Ct, Kt shown in FIG. 9. That is, the dynamic stiffness determination unit 106 includes a workpiece-side dynamic stiffness determination unit 121 and a tool-side dynamic stiffness determination unit 125.

[0084] The workpiece-side dynamic stiffness (Cw, Kw) and the tool-side dynamic stiffness (Ct, Kt) will be described with reference to FIG. 9. The workpiece-side dynamic stiffness (Cw, Kw) includes the workpiece W and is the dynamic stiffness on the workpiece W side regarding the table 20, the spindle device 30, and the device 40. On the other hand, the tool-side dynamic stiffness (Ct, Kt) includes the grinding wheel head T and is the dynamic stiffness regarding the grinding wheel table 50. Each will be described in detail below.

[0085] The workpiece-side dynamic stiffness (Cw, Kw) is the dynamic stiffness exhibited when the workpiece W is supported by the spindle device 30 and the device 40 as the workpiece support members constituting the grinding machine 2. The workpiece-side dynamic stiffness (Cw, Kw) is defined by the damping coefficient Cw and the spring constant Kw. The damping coefficient Cw is a value representing the relationship between the relative speed of the workpiece W with respect to the reference position of the grinding machine 2 and the external force received by the workpiece W. The spring constant Kw is a value representing the relationship between the relative position of the workpiece W with respect to the reference position of the grinding machine 2 and the external force received by the workpiece W. Note that any of the dynamic stiffnesses may include a mass term Mw in addition to the damping coefficient and the spring constant.

[0086] As shown in FIG. 9, the workpiece-side dynamic stiffness (Cw, Kw) can be decomposed into the workpiece dynamic stiffness (Cwa, Kwa), the support member dynamic stiffness (Cwb, Kwb), and the contact dynamic stiffness (Cwc, Kwc) between the workpiece W and the workpiece support members (spindle center 34, center rest 41).

[0087] And the workpiece-side dynamic stiffness determination unit 121 includes a workpiece dynamic stiffness calculation unit 122, a support member dynamic stiffness calculation unit 123, and a contact dynamic stiffness calculation unit 133. The workpiece dynamic stiffness calculation unit 122 calculates the workpiece dynamic stiffness data Cwa, Kwa corresponding to the type of the workpiece W acquired by the dynamic stiffness determination condition acquisition unit 105 from the dynamic stiffness table stored in the dynamic stiffness table storage unit 103a related to the workpiece W. Further, the support member dynamic stiffness calculation unit 123 calculates the support member dynamic stiffness data Cwb, Kwb corresponding to the type of the workpiece support member acquired by the dynamic stiffness determination condition acquisition unit 105 from the dynamic stiffness table stored in the dynamic stiffness table storage unit 103b related to each of the devices 20, 30, 40 constituting the workpiece support member.

[0088] The contact dynamic stiffness (Cwc, Kwc) is the dynamic stiffness between the workpiece W and the workpiece support members (spindle center 34, center rest 41), and is the dynamic stiffness exerted by the contact between the workpiece W and the workpiece support members (spindle center 34, center rest 41). And as described above, the contact dynamic stiffness (Cwc, Kwc) changes depending on the machining position I. The contact dynamic stiffness (Cwc, Kwc) is defined by the damping coefficient Cwc and the spring constant Kwc. The damping coefficient Cwc is a value representing the relationship between the relative speed between the workpiece W and the workpiece support members (spindle center 34, center rest 41) and the external force received by the workpiece W. The spring constant Kwc is a value representing the relationship between the relative position between the workpiece W and the workpiece support members (spindle center 34, center rest 41) and the external force received by the workpiece W. And the contact dynamic stiffness (Cwc, Kwc) is calculated by the contact dynamic stiffness calculation system 130 shown in FIG. 2.

[0089] 3-9. Contact Dynamic Stiffness Calculation System 130 The contact dynamic stiffness calculation system 130 shown in FIG. 2 is composed of a basic information acquisition unit 131, a differential bending angle calculation unit 132, and a contact dynamic stiffness calculation unit 133 included in the workpiece-side dynamic stiffness determination unit 121, and a correspondence relationship storage unit 103c included in the workpiece-side dynamic stiffness table storage unit 103.

[0090] The basic information acquisition unit 131 acquires basic information about the workpiece W. In this embodiment, the basic information acquisition unit 131 can have the same configuration as the basic information acquisition unit 141 shown in FIG. 3 described above. In this embodiment, the basic information includes information on the maximum support diameters dR, dL and the shape of the workpiece W together with the machining position I.

[0091] The differential bending angle calculation unit 132 shown in FIG. 2 calculates the differential bending angles ΔθR, ΔθL corresponding to the machining position I in the workpiece W based on the machining position I included in the basic information acquired by the basic information acquisition unit 131 and the correspondence relationship stored in the correspondence relationship storage unit 103c.

[0092] The contact dynamic stiffness calculation unit 133 calculates the contact dynamic stiffnesses Cwc and Kwc using the differential bending angles ΔθR and ΔθL. In the present embodiment, the contact dynamic stiffnesses Cwc and Kwc are calculated using the center hole sizes of the center holes WR and WL, which are the supported portions of the workpiece W, i.e., the maximum support diameters dR and dL, obtained by the basic information acquisition unit 131, together with the differential bending angles ΔθR and ΔθL. The contact dynamic stiffnesses (Cwc, Kwc) include the contact dynamic stiffnesses (Cwcr, Kwcr) between one center hole WR of the workpiece W and the center pusher 41, and the contact dynamic stiffnesses (Cwcl, Kwcl) between the other center hole WL of the workpiece W and the spindle center 34. And the contact dynamic stiffness data (Cwcr, Kwcr) and the contact dynamic stiffness data (Cwcl, Kwcl) can be defined as follows.

[0093] First, as shown in Fig. 8(b), when the differential bending angles ΔθR and ΔθL increase, the bending at the contact portion between the workpiece W and the workpiece support members (spindle center 34, center pusher 41) increases, and when the differential bending angles ΔθR and ΔθL decrease, the bending at the contact portion between the workpiece W and the workpiece support members (spindle center 34, center pusher 41) decreases. Also, when the maximum support diameters dR and dL increase, the center holes WR and WL become deeper, and the spindle center 34 and the center pusher 41 penetrate deeper into the center holes WR and WL, so the contact portion between the workpiece W and the workpiece support members (spindle center 34, center pusher 41) becomes larger. Conversely, when the maximum support diameters dR and dL decrease, the center holes WR and WL become shallower, and the spindle center 34 and the center pusher 41 penetrate shallower into the center holes WR and WL, so the contact portion between the workpiece W and the workpiece support members (spindle center 34, center pusher 41) becomes smaller. As a result, the spring constants Kwcr and Kwcl in the contact dynamic stiffness are inversely proportional to the differential bending angles ΔθR and ΔθL, respectively, and proportional to the maximum support diameters dR and dL.

[0094] Therefore, the spring constants Kwcr and Kwcl in the contact dynamic stiffness can be defined as follows according to the following relational expressions (Expression 1, Expression 2). Kwcr = α / ΔθR · dR (Expression 1) Kwcl = β / ΔθL · dL (Expression 2) Note that α and β are coefficients, and can be determined to be values such that the actually measured spring constants Kwcr and Kwcl calculated from predetermined differential bending angles ΔθR and ΔθL and predetermined maximum support diameters dR and dL obtained by actual measurement in advance match the spring constants Kwcr and Kwcl calculated by the above formulas (1) and (2).

[0095] On the other hand, since the damping coefficients Cwcr and Cwcl in the contact dynamic stiffness are mainly due to frictional damping, when only focusing on frictional damping, the differential bending angles ΔθR and ΔθL are proportional to the damping energy. Also, when the maximum support diameters dR and dL increase, the friction increases, and when the maximum support diameters dR and dL decrease, the friction decreases.

[0096] Therefore, the damping coefficients Cwcr and Cwcl in the contact dynamic stiffness can be defined respectively according to the following relational expressions (formulas (3) and (4)). Cwcr = γ·ΔθR·dR (formula (3)) Cwcl = δ·ΔθL·dL (formula (4)) Note that γ and δ are coefficients, and can be determined in the same way as α and β.

[0097] As described above, the contact dynamic stiffness calculation unit 133 can calculate the contact dynamic stiffness Cwc (Cwcr and Cwcl) and Kwc (Kwcr and Kwcl) from ΔθR, ΔθL and dR, dL based on the relational expressions of the above formulas (1) to (4).

[0098] As shown in FIG. 9, the tool-side dynamic stiffness (Ct, Kt) includes the grinding wheel headstock T and is the dynamic stiffness with respect to the grinding wheel stand 50. The tool-side dynamic stiffness (Ct, Kt) is defined by the damping coefficient Ct and the spring constant Kt. The damping coefficient Ct is a value representing the relationship between the relative speed of the grinding wheel headstock T with respect to the reference position on the grinding wheel stand 50 and the external force received by the grinding wheel headstock T. The spring constant Kt is a value representing the relationship between the relative position of the grinding wheel headstock T with respect to the reference position on the grinding wheel stand 50 and the external force received by the grinding wheel headstock T. And the tool-side dynamic stiffness (Ct, Kt) includes the dynamic stiffness (Cta, Kta) of the grinding wheel headstock T and the dynamic stiffness (Ctb, Ktb) exhibited when the grinding wheel headstock T is supported by the grinding wheel stand body 51. Note that any of the dynamic stiffnesses may include a mass term in addition to the damping coefficient and the spring constant.

[0099] The tool-side dynamic stiffness (Ct, Kt) can be calculated by the tool-side dynamic stiffness determination unit 125 shown in FIG. 2 based on the dynamic stiffness determination conditions acquired by the dynamic stiffness determination condition acquisition unit 105 and the correspondence between the dynamic stiffness determination conditions stored in the tool-side dynamic stiffness table storage unit 104 and the tool-side dynamic stiffness data Ct, Kt.

[0100] 3-10. Correction amount calculation unit 107 The correction amount calculation unit 107 calculates the correction amount of the relative displacement of the grinding wheel T and the workpiece W in the X-axis direction due to the grinding resistance based on each dynamic stiffness data determined by the dynamic stiffness determination unit 106. The correction amount regarding the displacement can be obtained from each dynamic stiffness data and the grinding resistance. That is, the correction amount regarding the displacement can be calculated from the grinding resistance, the workpiece-side dynamic stiffness data Cw, Kw, and the tool-side dynamic stiffness data Ct, Kt.

[0101] However, in the present embodiment, the workpiece-side dynamic stiffness data Cw, Kw includes the workpiece dynamic stiffness data Cwa, Kwa, the support member dynamic stiffness data Cwb, Kwb, and the contact dynamic stiffness data Cwc, Kwc respectively. That is, the correction amount regarding the displacement can be calculated from the grinding resistance, the workpiece-side dynamic stiffness data Cwa, Kwa, Cwb, Kwb, Cwc, Kwc, and the tool-side dynamic stiffness data Ct, Kt.

[0102] The correction amount calculation unit 107 outputs the calculated correction amount to the estimation unit 102. As described above, the estimation unit 102 estimates the estimation target based on the relative position between the workpiece W and the grinding wheel T acquired by the command value acquisition unit 101, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T. However, due to the grinding resistance, the relative position between the workpiece W and the grinding wheel T becomes a position different from the relative position by the command value.

[0103] 3-11. Output unit 108 The output unit 108 outputs the estimation target estimated by the estimation unit 102. When estimating the estimation target, the estimation unit 102 adds, as the relative position between the workpiece W and the grinding wheel T, the correction amount calculated by the correction amount calculation unit 107 in addition to the relative position acquired by the command value acquisition unit 101, and uses the relative position considering the rotational runout of the workpiece W based on the analysis result of the workpiece rotational runout analysis system 140. That is, the estimation unit 102 estimates the estimation target based on the relative position by the command value, the correction amount calculated using each dynamic stiffness data, and the rotational runout of the workpiece W.

[0104] In particular, in the first embodiment, the correction amount calculation unit 107 outputs the calculated correction amount to the interference amount calculation unit 111 of the estimation unit 102. As described above, the interference amount calculation unit 111 calculates the interference amount between the workpiece W and the grinding wheel T based on the relative position between the workpiece W and the grinding wheel T acquired by the command value acquisition unit 101, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T. However, due to the grinding resistance, the relative position between the workpiece W and the grinding wheel T is different from the relative position by the command value.

[0105] Therefore, as the relative position between the workpiece W and the grinding wheel T used for calculating the interference amount, the interference amount calculation unit 111 adds the correction amount calculated by the correction amount calculation unit 107 and the relative position considering the rotational runout of the workpiece W analyzed by the workpiece rotational runout analysis system 140 to the relative position acquired by the command value acquisition unit 101. That is, the interference amount calculation unit 111 calculates the interference amount based on the relative position by the command value, the correction amount calculated using each dynamic stiffness data, and the rotational runout of the workpiece W.

[0106] Since the interference amount calculation unit 111 calculates the interference amount considering the correction amount and the rotational runout, the grinding efficiency calculation unit 112, the grinding characteristic determination unit 113, and the grinding resistance calculation unit 114 obtain the grinding efficiency Z', the grinding characteristic kc, and the grinding resistance Fn obtained based on the interference amount considering the correction amount and the rotational runout.

[0107] The output unit 108 outputs the estimation target estimated by the estimation unit 102. That is, the output unit 108 can output at least one estimation result of the state of the workpiece W or the grinding wheel T during grinding, the shape of the workpiece W, the shape of the grinding wheel T, and the mechanical state of the processing system 1 (corresponding to the mechanical state of the grinding machine 2). The output unit 108 may, for example, teach the estimation result to an instruction device (not shown). Further, the output unit 108 can also output the estimation result to the control device 3a of the grinding machine 2. In this case, the control device 3a can correct, for example, the grinding processing conditions using the estimation result. That is, the control device 3a can control the grinding process using the estimation result.

[0108] Also, the control device 3a is configured to perform the above-described various processes using the estimation result. In addition to this, the control device 3a can also control the processing using various dynamic rigidities determined by the dynamic rigidity determination unit 106 regardless of the estimation result. For example, the control device 3a can adjust the pressing force by the spindle center 34 and the center rest 41, the gripping force of the chuck, etc. using various dynamic rigidities determined by the dynamic rigidity determination unit 106 regardless of the estimation result.

[0109] 4. Operational Effects According to the workpiece rotational vibration analysis system 140 of the present embodiment, after calculating the rotation center S1 of the workpiece W based on the workpiece weight deflection Lm generated in the workpiece support members 34 and 41 due to the weight Mw of the workpiece W, the rotational vibration of the workpiece W centered on the rotation center S1 of the workpiece W is analyzed based on the indentation deflection Lf generated in the workpiece W by the indentation forces FR and FL applied to the workpiece W from the workpiece support members 34 and 41. Thereby, the rotational vibration of the workpiece W can be calculated with high accuracy.

[0110] Further, in the present embodiment, based on the workpiece weight deflection Lm, the workpiece weight bending angles θ’CL and θ’CR, which are the bending angles of the workpiece support members 34 and 41 at the contact portion between the workpiece W and the workpiece support members 34 and 41 caused by the weight Mw of the workpiece W in the initial state where no acting force is applied from the tool T to the workpiece W, are calculated by the workpiece weight bending angle calculation unit 143. Further, based on the workpiece weight bending angles θ’CL and θ’CR and the pushing forces FL and FR, the bending component force F’B of the workpiece W due to the weight Mw and the pushing forces FL and FR of the workpiece W, and the bending load position I‘ where the bending component force F’B acts on the workpiece W are calculated by the pushing bending load analysis unit 144. Further, the total deflection L generated in the workpiece support member by the weight of the workpiece and the bending component force F’B of the workpiece all is calculated by the support member total deflection calculation unit 145 is provided. Then, the pushing deflection calculation unit 146 calculates the pushing deflection Lf from the difference between the total deflection L in the workpiece support members 34 and 41 all and the workpiece weight deflection Lm, and the workpiece rotational runout analysis unit 148 analyzes the rotational runout of the workpiece W at the machining position I based on the pushing deflection Lf at the machining position I. Thereby, the rotational runout of the workpiece W at the machining position I can be analyzed with high accuracy and used for estimating the machining result of the workpiece W.

[0111] In addition, in the present embodiment, the workpiece support members 34 and 41 include a first workpiece support member 34 that presses into the center hole WL, which is one end of the workpiece W, and a second workpiece support member 41 that presses into the center hole WR, which is the other end, and are configured to sandwich the workpiece W between the first workpiece support member 34 and the second workpiece support member 41. Then, the workpiece weight bending angle calculation unit 143 calculates a first bending angle θ'CL, which is the bending angle of the workpiece support member 34 at the contact portion between one end WL of the workpiece W and the first workpiece support member 34, and a second bending angle θ'CR, which is the bending angle of the workpiece support member 41 at the contact portion between the other end WR of the workpiece W and the second workpiece support member 41. Further, the push-in bending load analysis unit 144 calculates a bending component force F'B and a bending load position I' based on the first bending angle θ'CL, the second bending angle θ'CR, and the push-in forces FL and FR in the initial state. Thereby, in the configuration in which the workpiece W is sandwiched at both ends by the workpiece support members 34 and 41, the rotational runout of the workpiece W can be analyzed with high precision.

[0112] Further, the machining system 1 of the present embodiment includes a workpiece rotational vibration analysis system 140, and the bending angles of the workpiece W at the contact portions between the workpiece W and the workpiece support members 34 and 41, namely the workpiece bending angles θWL and θWR, and the bending angles of the workpiece support members 34 and 41, namely the support member bending angles θCL and θCR, when changing from the initial state to the operating state where the acting force of the tool T is applied to the workpiece W. The differential bending angle calculation unit 132 calculates the differential bending angles ΔθL and ΔθR, which are the differences therebetween. Further, based on the basic information acquired by the basic information acquisition unit 131 and the differential bending angles ΔθL and ΔθR calculated by the differential bending angle calculation unit 132, the spring constant Kwc and the damping coefficient Cwc at the contact portion between the workpiece W and the workpiece support members 34 and 41 are calculated, and the contact dynamic stiffness (Kwc, Cwc) of the workpiece W is calculated based on the spring constant Kwc and the damping coefficient Cwc. Further, an estimation unit 102 estimates the machining result of the workpiece W based on the dynamic stiffness on the workpiece side including the contact dynamic stiffness (Kwc, Cwc) calculated by the contact dynamic stiffness calculation unit 133 and the rotational vibration of the workpiece W. Thus, the contact dynamic stiffness at the contact portion between the workpiece W and the workpiece support members 34 and 41 can be calculated with high precision, and the rotational vibration of the workpiece W can be analyzed with high precision. Therefore, the machining result of the workpiece W can be estimated with high precision.

[0113] Moreover, the machining system 1 of the present embodiment includes a machining device 2 for machining the workpiece W and a control device 3a for controlling the machining by the machining device 2 based on the machining result estimated by the estimation unit 102. Thus, since the workpiece W can be machined by reflecting the machining result estimated based on the rotational vibration of the workpiece W analyzed with high precision and the workpiece-side dynamic stiffness (Cw, Kw) including the contact dynamic stiffness (Cwc, Kwc), the workpiece W can be formed into the target shape with higher precision.

[0114] In addition, in the first embodiment, the workpiece-side dynamic stiffness (Cw, Kw) is separated into the workpiece dynamic stiffness (Cwa, Kwa), the support member dynamic stiffness (Cwb, Kwb), and the contact dynamic stiffness (Cwc, Kwc). By separating the respective dynamic stiffness data in this way, it becomes easier to determine the respective dynamic stiffness data. For example, even if each of the devices 20, 30, and 40 constituting the workpiece W and the workpiece support member is the same, when only the pressing force by the spindle center 34 and the center rest center 41 is adjusted, only the contact dynamic stiffness data Cwc, Kwc is changed. Therefore, the arithmetic processing becomes easy. For example, in the case of simultaneously performing the estimation processing by the machining estimation device 3b and the control of the grinding process by the control device 3a, high-precision grinding can be realized by performing the arithmetic processing at high speed.

[0115] As described above, according to the above aspect, it is possible to provide a workpiece rotational runout analysis system 140 that can calculate the rotational runout of the workpiece W with high accuracy in consideration of the weight Mw of the workpiece W.

[0116] The present invention is not limited to the first embodiment, and can be applied to various embodiments without departing from the gist thereof. For example, in the first embodiment, the grinding process using the grinding machine 2 has been described. Instead of this, the cutting process using a lathe or a machining center can be similarly applied.

Description of Reference Numerals

[0117] 1 Machining system 2 Grinding machine (processing device) 3a Control device 3b Machining estimation device 34 Spindle center (workpiece support member) 41 Center rest center (workpiece support member) 102 Estimation unit 130 Contact dynamic stiffness calculation system 132 Differential bending angle calculation unit 133 Contact dynamic stiffness calculation unit 140 Workpiece rotational runout analysis system 141 Basic information acquisition unit 142 Workpiece Weight Deflection Calculation Unit 143 Workpiece Weight Bending Angle Calculation Unit 144 Press-in Bending Load Analysis Unit 145 Total Deflection Calculation Unit of Support Member 146 Press-in Deflection Calculation Unit 147 Workpiece Rotation Center Calculation Unit 148 Workpiece Rotation Runout Analysis Unit

Claims

1. A workpiece rotational vibration analysis system for analyzing the rotational vibration of a workpiece being machined by a tool while being supported by a workpiece support member, comprising: a basic information acquisition unit that acquires basic information regarding the workpiece, including information on the machining position of the workpiece; a workpiece weight deflection calculation unit that calculates the workpiece weight deflection generated in the workpiece support member due to the weight of the workpiece; a pushing deflection calculation unit that calculates the pushing deflection generated in the workpiece support member due to the pushing force with which the workpiece support member pushes the workpiece; a workpiece rotation center calculation unit that calculates the rotation center of the workpiece when the workpiece is rotated via the workpiece support member based on the workpiece weight deflection; a workpiece rotational vibration analysis unit that analyzes the rotational vibration of the workpiece with respect to the rotation center of the workpiece when the workpiece is rotated via the workpiece support member based on the pushing deflection; A workpiece rotational vibration analysis system comprising the above components.

2. a workpiece weight bending angle calculation unit that calculates a workpiece weight bending angle, which is the bending angle of the workpiece support member at the contact portion between the workpiece and the workpiece support member caused by the weight of the workpiece in an initial state where no acting force is applied to the workpiece from the tool, based on the workpiece weight deflection; a pushing bending load analysis unit that calculates the bending component force of the workpiece due to the weight and pushing force of the workpiece and the bending load position where the bending component force acts on the workpiece based on the workpiece weight bending angle and the pushing force; a support member total deflection calculation unit that calculates the total deflection generated in the workpiece support member by the weight of the workpiece and the bending component force of the workpiece; comprising: The pushing deflection calculation unit calculates the pushing deflection from the difference between the total deflection in the workpiece support member and the workpiece weight deflection. The workpiece rotational vibration analysis unit analyzes the rotational vibration of the workpiece at the machining position based on the pushing deflection at the machining position. The workpiece rotational vibration analysis system according to Claim 1.

3. The workpiece support member includes a first workpiece support member that pushes one end of the workpiece and a second workpiece support member that pushes the other end, and is configured to sandwich the workpiece between the first workpiece support member and the second workpiece support member. The workpiece weight bending angle calculation unit calculates a first bending angle that is the bending angle of the workpiece support member at the contact portion between one end of the workpiece and the first workpiece support member, and a second bending angle that is the bending angle of the workpiece support member at the contact portion between the other end of the workpiece and the second workpiece support member, The pushing-in bending load analysis unit calculates the bending component force and the bending load position based on the first bending angle, the second bending angle, and the pushing-in force in the initial state. The workpiece rotational runout analysis system according to claim 2.

4. The workpiece rotational runout analysis system according to claim 1 or 2, A differential bending angle calculation unit that calculates a differential bending angle, which is the difference between the workpiece bending angle, which is the bending angle of the workpiece at the contact portion between the workpiece and the workpiece support member, and the support member bending angle, which is the bending angle of the workpiece support member, when changing from an initial state in which no acting force is applied to the workpiece from the tool to an acting state in which the acting force of the tool is applied to the workpiece, A contact dynamic stiffness calculation unit that calculates a spring constant and a damping coefficient at the contact portion between the workpiece and the workpiece support member based on the basic information acquired by the basic information acquisition unit and the differential bending angle calculated by the differential bending angle calculation unit, and calculates the contact dynamic stiffness of the workpiece based on the spring constant and the damping coefficient, A processing system comprising an estimation unit that estimates a processing result of the workpiece based on the dynamic stiffness on the workpiece side including the contact dynamic stiffness calculated by the contact dynamic stiffness calculation unit and the rotational runout of the workpiece.

5. A processing device that processes the workpiece, The processing system according to claim 4, further comprising a control device that controls the processing by the processing device based on the processing result estimated by the estimation unit.

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