Processing estimation device

Abstract

In a processing device (2, 302) for processing a workpiece (W) with a tool (T, T2), a processing estimation device (3, 5, 303) estimates at least one among the condition of the workpiece (W) or the tool (T, T2), the shape of the workpiece (W), the shape of the tool (T, T2) and the machine condition of the processing device (2, 302) at the time of processing using contact dynamic stiffness data (Ci, Ki) between the workpiece (W) and the tool (T, T2) demonstrated by contact between the workpiece (W) and the tool (T, T2) when processing.

Description

[Technical Field]

[0001] The present disclosure relates to a processing estimation device. [Background technology]

[0002] Patent Document 1 describes a grinding simulation device. The grinding simulation is performed by repeatedly calculating the amount of workpiece removal based on the relative positions of the workpiece and the grinding wheel, calculating the grinding resistance based on the amount of removal, and calculating a correction amount for the relative position based on the grinding resistance. The calculation of the correction amount uses previously measured support stiffness for supporting the workpiece and the support stiffness for supporting the grinding wheel.

[0003] Patent Document 2 describes that when a workpiece is ground with a grinding wheel, the depth of the grinding marks on the workpiece is calculated taking into account the static contact stiffness between the workpiece and the grinding wheel. The static contact stiffness used here is calculated using the theoretical static contact stiffness during grinding, rather than a value measured when the grinding wheel is stationary. The static contact stiffness is expressed by the spring constant K between the workpiece and the grinding wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-153907 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-208812 Summary of the Invention [Problem to be solved by the invention]

[0005] In the grinding simulation device described in Patent Document 1, the amount of correction for the relative position between the workpiece and the grinding wheel is calculated using the support stiffness of the workpiece and the support stiffness of the grinding wheel in addition to the grinding resistance. However, the amount of correction for the relative position cannot be calculated with high accuracy simply by using the support stiffness of the workpiece and the support stiffness of the grinding wheel. It has been found that one of the reasons for this is the influence of the contact stiffness between the workpiece and the grinding wheel.

[0006] It is believed that the relative position between the workpiece and the grinding wheel can be calculated with high accuracy by using the static contact stiffness described in Patent Document 2. However, even if the static contact stiffness between the workpiece and the grinding wheel is used, there is still room for improvement in accuracy.

[0007] Furthermore, the objects to be estimated are not limited to the correction amount of the relative position between the workpiece and the grinding wheel as described above, but also include the shape of the workpiece, the shape of the grinding wheel, the state of the workpiece or the grinding wheel during grinding, the mechanical state of the grinding machine, etc. The same applies to cutting processes other than grinding processes.

[0008] The present disclosure aims to provide a processing and estimation device that can estimate an estimation target with higher accuracy. [Means for solving the problem]

[0009] One aspect of the present disclosure is a process Grinding wheel In a processing device that processes a workpiece by the above method, at least one of a state of the workpiece or the tool during processing, a shape of the workpiece, a shape of the tool, and a mechanical state of the processing device is estimated using data on dynamic contact stiffness between the workpiece and the tool that is exerted by contact between the workpiece and the tool during processing, The contact dynamic stiffness data is data generated from the relationship between an excitation force and a displacement of the workpiece when an excitation force is applied to the workpiece while the workpiece is being machined by the tool. the law of nature, The data is caused by the elastic deformation of the grinding wheel, and corresponds to the contact arc length of the grinding wheel contacting the workpiece during grinding. This is a processing estimation device. Another aspect of the present disclosure is A machining estimation device for a machining device that machines a workpiece with a tool, the machining estimation device using data on dynamic contact stiffness between the workpiece and the tool that is exerted by contact between the workpiece and the tool during machining to estimate at least one of a state of the workpiece or the tool during machining, a shape of the workpiece, a shape of the tool, and a mechanical state of the machining device, The contact dynamic stiffness data is data generated from the relationship between an excitation force and a displacement of the workpiece when an excitation force is applied to the workpiece while the workpiece is being machined by the tool. The processing estimation device includes: a contact dynamic stiffness table storage unit that stores in advance a correspondence relationship between the contact dynamic stiffness data and machining conditions including at least one of the relative position between the workpiece and the tool, the rotational speed of the tool which is a rotating body, and the rotational speed of the workpiece; an estimation unit that estimates at least one of a state of the workpiece or the tool during machining, a shape of the workpiece, a shape of the tool, and a mechanical state of the machining device, using the machining conditions at the time of estimation and the correspondence stored in the contact dynamic stiffness table storage unit; A processing estimation device comprising: Another aspect of the present disclosure is a machining estimation device that, in a machining device that machines a workpiece with a tool, estimates at least one of a state of the workpiece or the tool during machining, a shape of the workpiece, a shape of the tool, and a mechanical state of the machining device using data of contact dynamic stiffness between the workpiece and the tool that is exerted by contact between the workpiece and the tool during machining, the contact dynamic stiffness data is data generated from a relationship between an excitation force and a displacement of the workpiece when an excitation force is applied to the workpiece while the workpiece is being machined by the tool, The processing estimation device includes: the contact dynamic stiffness data; data of workpiece support dynamic stiffness in a workpiece support device constituting the processing apparatus, the workpiece support dynamic stiffness being exerted when the workpiece is supported by the workpiece support device; and using tool support dynamic stiffness data of a tool support device that is included in the processing apparatus and that is exhibited when the tool is supported by the tool support device, The machining estimation device estimates at least one of the state of the workpiece or the tool during machining, the shape of the workpiece, the shape of the tool, and the machine state of the machining device. [Effects of the Invention]

[0010] According to the above aspect, at least one of the state of the workpiece or tool during machining, the shape of the workpiece, the shape of the tool, and the mechanical state of the machining device is estimated using dynamic contact stiffness data between the workpiece and the tool. The dynamic contact stiffness data is represented by the spring constant and damping coefficient between the workpiece and the tool exerted by contact between the workpiece and the tool. In this way, by using dynamic contact stiffness data including the spring constant and damping coefficient, various estimation targets can be estimated with high accuracy.

[0011] As described above, according to the above aspect, it is possible to provide a processing estimation device that can estimate an estimation target with higher accuracy.

[0012] It should be noted that the reference symbols in parentheses in the claims indicate the correspondence with the specific means described in the embodiments to be described later, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing a processing system including a processing device and a processing estimation device according to a first embodiment. [Figure 2] 1 is a functional block diagram of a processing estimation device according to a first embodiment. FIG. [Figure 3] FIG. 2 is a schematic diagram showing interference between a workpiece and a grinding wheel during grinding. [Figure 4] This is a diagram showing the shape of a workpiece in a grinding simulation using a group of radial line segments, and shows how the workpiece, represented by the radial line segments, interferes with the outer circumferential line of the grinding wheel during grinding. [Figure 5] 1A and 1B are schematic diagrams showing contact dynamic stiffness, workpiece support dynamic stiffness, and tool support dynamic stiffness in grinding. [Figure 6] FIG. 10 is a diagram showing a contact dynamic stiffness table obtained by actual measurement. [Figure 7] FIG. 10 is a diagram showing a contact dynamic stiffness table obtained by actual measurement and interpolation processing. [Figure 8] FIG. 10 is a diagram showing a workpiece support dynamic stiffness table. [Figure 9] 10 is a flowchart showing a contact dynamic stiffness data acquisition process. [Figure 10] FIG. 10 is a plan view of the grinding machine when acquiring contact dynamic stiffness data. [Figure 11] 10A and 10B are diagrams illustrating the state of the grinding machine in some steps of the contact dynamic stiffness data acquisition process. [Figure 12] FIG. 10 is a functional block diagram of a processing estimation device according to a second embodiment. [Figure 13] FIG. 10 is a diagram showing a comprehensive dynamic stiffness table obtained by actual measurement and interpolation processing. [Figure 14] FIG. 10 is a diagram showing a processing system including a processing device and a processing estimation device according to a third embodiment. [Figure 15] 1 is a schematic diagram showing contact dynamic stiffness, workpiece support dynamic stiffness, and tool support dynamic stiffness in cutting processing. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Embodiment 1) 1.Configuration of Processing Estimation System 1 The processing estimation system 1 will be described with reference to Fig. 1. The processing estimation system 1 targets grinding processing using a grinding machine 2. The processing estimation system 1 includes the grinding machine 2 as a processing device, and a processing estimation device 3.

[0015] The grinding machine 2 rotates the workpiece W, rotates a grinding wheel T as a tool that is a rotating body, and moves the grinding wheel T relatively close to the workpiece W in a direction intersecting the axis of the workpiece W, thereby grinding the outer or inner peripheral surface of the workpiece W. The grinding machine 2 can be a table traverse type grinding machine, a wheelhead traverse type grinding machine, or the like. The grinding machine 2 can also be a cylindrical grinding machine, a cam grinding machine, or the like.

[0016] In this embodiment, as shown in Fig. 1, the workpiece W has a shaft portion Wa as a non-machined portion and multiple machined portions Wb whose outer circumferential surfaces are to be ground. The machined portions Wb have, for example, a cylindrical outer circumferential surface coaxial with the shaft portion Wa. However, the workpiece W shown in Fig. 1 is just one example, and the grinding machine 2 can grind workpieces having various shapes.

[0017] The processing estimation device 3 estimates at least one of the state of the workpiece W or the grinding wheel T during grinding processing on the grinding machine 2, the shape of the workpiece W, the shape of the grinding wheel T, and the mechanical state of the grinding machine 2. The processing estimation device 3 performs estimation processing of the above estimation target by inputting information used in the grinding processing and performing a simulation.

[0018] The processing estimation device 3 can function as a simulation device independent of the grinding machine 2, or as a simulation device that operates in conjunction with the grinding machine 2. In the former case, for example, optimal grinding conditions can be determined without actually grinding the workpiece W. In the latter case, the processing estimation device 3 can perform processing in parallel with the grinding of the workpiece W by the grinding machine 2, thereby correcting the grinding conditions or operating to affect various controls. The processing estimation device 3 can also be an embedded system in the grinding machine 2.

[0019] 2. Grinding machine 2 configuration An example of the configuration of the grinding machine 2 will be described in detail with reference to Fig. 1. The grinding machine 2 is exemplified by 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 T in a direction intersecting the axis of the workpiece W. In addition, in this embodiment, the grinding machine 2 is exemplified by a case where the grinding wheel T grinds the cylindrical outer peripheral surface of the workpiece W.

[0020] The grinding machine 2 includes a bed 10, a table 20, a spindle device 30, a tailstock device 40, a grinding wheel head 50, a sizing device 60, and a control device 70. The bed 10 is installed on an installation surface. The bed 10 is formed so that the width (length in the Z-axis direction) of the front side in the X-axis direction (lower side in Fig. 1) is long, and the width of the back side in the X-axis direction (upper side in Fig. 1) is short.

[0021] Bed 10 is provided with 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. Bed 10 also has a Z-axis drive mechanism 12 that drives along Z-axis guide surface 11. In this embodiment, Z-axis drive mechanism 12 includes a ball screw mechanism 12a and a Z-axis motor 12b. Ball screw mechanism 12a extends parallel to Z-axis guide surface 11, and Z-axis motor 12b drives ball screw mechanism 12a.

[0022] A Z-axis drive circuit and Z-axis detector 12c (not shown) are provided to drive Z-axis drive mechanism 12. The Z-axis drive circuit includes an amplifier circuit and drives Z-axis motor 12b. In this embodiment, Z-axis detector 12c is an angle detector such as an encoder, which detects the angle of the rotation shaft of Z-axis motor 12b. Note that Z-axis drive mechanism 12 may also use a linear motor instead of the ball screw mechanism 12a.

[0023] Bed 10 also has a guide surface 13 on its upper surface on the rear side in the X-axis direction, which extends in a direction intersecting the Z-axis direction. In this embodiment, guide surface 13 is an X-axis guide surface that extends in the X-axis direction, which is perpendicular to the Z-axis. Bed 10 also has an X-axis drive mechanism 14 that drives along X-axis guide surface 13. In this embodiment, X-axis drive mechanism 14 includes a ball screw mechanism 14a and an X-axis motor 14b. Ball screw mechanism 14a extends parallel to X-axis guide surface 13, and X-axis motor 14b drives ball screw mechanism 14a.

[0024] An X-axis drive circuit and an X-axis detector 14c (not shown) are provided to drive the X-axis drive mechanism 14. The X-axis drive circuit includes an amplifier circuit and drives the X-axis motor 14b. In this embodiment, the X-axis detector 14c is an angle detector such as an encoder, which detects the angle of the rotation shaft of the X-axis motor 14b. Note that the X-axis drive mechanism 14 may also be configured with a linear motor instead of the ball screw mechanism 14a.

[0025] Table 20 is formed in an elongated shape and is supported movably in the Z-axis direction (horizontal left-right direction) on Z-axis guide surface 11 of bed 10. Table 20 is also fixed to a ball screw nut of Z-axis ball screw mechanism 12a, and moves in the Z-axis direction by rotational driving of Z-axis motor 12b.

[0026] The spindle device 30 constitutes a workpiece support device. The spindle device 30 supports the workpiece W and drives it to rotate. 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).

[0027] The spindle housing 31 is fixed on the table 20. The spindle 32 is rotatably supported by the spindle housing 31 via a bearing. A spindle motor 33 drives the spindle 32 to rotate. A spindle center 34 supports one axial end face of the workpiece W. The spindle center 34 is fixed to the spindle 32 and is rotatable relative to the spindle housing 31. However, if the spindle unit 30 is equipped with a turning member such as a cage (not shown), the spindle center 34 may be fixed to the spindle housing 31 and installed so as to be non-rotatable relative to the spindle housing 31. Furthermore, the spindle unit 30 may be equipped with a chuck for gripping the workpiece W instead of the spindle center 34. The chuck is rotationally driven by being connected to the spindle 32.

[0028] The spindle detector 35 and the spindle drive circuit are provided to drive the spindle motor 33. In this embodiment, the spindle detector 35 is an angle detector such as an encoder, and detects the angle of the rotation shaft of the spindle motor 33. The spindle drive circuit includes an amplifier circuit and drives the spindle motor 33.

[0029] The tailstock device 40, together with the spindle device 30, constitutes a workpiece support device. The tailstock device 40 is arranged on the other end side of the table 20 in the Z-axis direction. The tailstock device 40 is provided so as to be movable in the Z-axis direction on the table 20. The tailstock device 40 is equipped with a tailstock center 41. The tailstock center 41 supports the end face of the other axial end of the workpiece W. The tailstock center 41 may be provided so as to be non-rotatable or so as to be rotatable. Note that when the grinding machine 2 grinds the inner peripheral surface of the workpiece W, the tailstock device 40 is not necessary.

[0030] The tailstock center 41 may be positioned at a fixed position relative to the workpiece W, or may be provided so as to be movable in the axial direction of the workpiece W relative to the workpiece W. In the latter case, the tailstock center 41 may be configured so that the pressing force in the axial direction of the workpiece W against the workpiece W is adjustable. The pressing force can be controlled by means of adjusting a spring force, means of adjusting a fluid pressure, or the like.

[0031] The wheel head 50 is provided with a grinding wheel T and rotates the grinding wheel T. In addition to the grinding wheel T, the wheel head 50 is provided with a wheel head body 51, a grinding wheel spindle 52, a grinding wheel motor 53, and a grinding wheel drive circuit (not shown).

[0032] The grinding wheel T is formed in a disk shape. The grinding wheel T is used to grind the outer or inner surface of the workpiece W. The grinding wheel T is composed of multiple abrasive grains fixed with a binder. The abrasive grains used include general abrasive grains made of ceramic materials such as alumina and silicon carbide, and super abrasive grains such as diamond and CBN.

[0033] Binders include vitrified (V), resinoid (B), rubber (R), silicate (S), shellac (E), metal (M), electroplated (P), and magnesia cement (Mg). Furthermore, grinding wheels T are available in porous and non-porous configurations. Depending on the type of binder and the presence or absence of pores, grinding wheels T can be elastically deformable or virtually non-elastically deformable. Elastic modulus of elasticity of elastically deformable grinding wheels T varies depending on the type of binder, the presence or absence of pores, and the porosity.

[0034] The wheel head body 51 is formed, for example, in a rectangular shape in a plan view, and is supported on the X-axis guide surface 13 of the bed 10 so as to be movable in the X-axis direction (horizontal front-to-back direction). The wheel head body 51 is also 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 wheel head body 51 constitutes a grinding wheel support device that supports the grinding wheel T.

[0035] The grinding wheel spindle 52 is rotatably supported by the wheel head body 51 via a bearing. A grinding wheel T is fixed to the tip of the grinding wheel spindle 52, and the grinding wheel T rotates as the grinding wheel spindle 52 rotates. A grinding wheel motor 53 drives the grinding wheel spindle 52 to rotate. The bearing may be a hydrostatic bearing, a rolling bearing, or the like.

[0036] The grinding wheel motor 53 transmits the rotational driving force to the grinding spindle 52 via, for example, a belt. However, the grinding wheel motor 53 may be arranged coaxially with the grinding spindle 52. In general, the rotation speed of the grinding wheel T driven by the grinding wheel motor 53 is higher than the rotation speed of the workpiece W driven by the spindle motor 33. A grinding wheel drive circuit is provided to drive the grinding wheel motor 53. The grinding wheel drive circuit includes an amplifier circuit and drives the grinding wheel motor 53.

[0037] The sizing device 60 is provided on the upper surface of the bed 10 and measures the outer diameter dimension of the workpiece W. The sizing device 60 is equipped with, for example, a pair of contacts that can come into contact with the outer peripheral surface of the workpiece W, and measures the outer diameter dimension at the contact point with the workpiece W.

[0038] The control device 70 is a CNC (Computer Numerical Control) device that controls machining. The control device 70 is a programmable logic controller (PLC) device. That is, the control device 70 drives the Z-axis drive mechanism 12 and the X-axis drive mechanism 14, which serve as moving devices, based on the grinding program and the measurement results from the sizing device 60, to control the positions of the table 20 and the wheel head 50. That is, the control device 70 controls the positions of the table 20, the wheel head 50, etc., thereby moving the workpiece W and the grinding wheel T closer to or farther apart from each other. Furthermore, the control device 70 controls the spindle device 30 and the wheel head 50. That is, the control device 70 controls the rotation of the spindle 32 and the grinding wheel T.

[0039] 3. Configuration of the processing estimation device 3 The configuration of the machining estimation device 3 will be described with reference to Fig. 2. The machining estimation device 3 includes a command value acquisition unit 101, an estimation unit 102, a contact dynamic stiffness table storage unit 103, a workpiece support dynamic stiffness table storage unit 104, a grinding wheel support dynamic stiffness table storage unit 105, a machining condition acquisition unit 106, a dynamic stiffness determination unit 107, a correction amount calculation unit 108, and an output unit 109.

[0040] The command value acquisition unit 101 acquires command values ​​for controlling the grinding machine 2 in the grinding process. When the processing estimation device 3 is a simulation device independent of the grinding machine 2, the command value acquisition unit 101 inputs a grinding program and configuration information of the grinding machine 2, and generates command values ​​by calculation for controlling each part of the grinding machine 2. When the processing estimation device 3 functions as a simulation device that operates in conjunction with the grinding process by the grinding machine 2, the command value acquisition unit 101 can acquire command values ​​directly from the control device 70 of the grinding machine 2.

[0041] The estimation unit 102 executes a grinding simulation using the command values ​​acquired by the command value acquisition unit 101 to estimate at least one 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 grinding machine 2. 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 at each location on the outer 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 at an intermediate stage of grinding and the shape at the end of grinding. The shape of the grinding wheel T includes the shape at an intermediate stage of grinding and the shape at the end 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.

[0042] In this embodiment, the estimation unit 102 performs a grinding simulation in which the shape of the workpiece W changes sequentially, and thereby estimates the shape of the workpiece W, the state of the workpiece W, and the mechanical state of the grinding machine 2. In this embodiment, the grinding simulation is performed assuming that the grinding wheel T does not deform. Note that the estimation unit 102 can also estimate the grinding resistance generated at each location on the outer circumferential surface of the grinding wheel T, in addition to the above estimation targets.

[0043] 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 .

[0044] The interference amount calculation unit 111 calculates the amount of interference between the workpiece W and the grinding wheel T based on the relative positions of 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 corresponds to the amount of radial grinding of the workpiece W at each portion in the circumferential direction of the workpiece W. In other words, the interference amount is the amount of removal of the workpiece W ground by the grinding wheel T, more specifically, the amount of radial removal of the workpiece W at each portion in the circumferential direction of the workpiece W. As shown in FIG. 3, the interference amount is the volume of the portion where the workpiece W interferes with the grinding wheel T (the shaded portion in FIG. 3: the interference area).

[0045] The interference amount calculation unit 111 geometrically calculates the amount of interference 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 on the right side of FIG. 4, the outer peripheral surface shape of the workpiece W is expressed by a group of multiple radial line segments on a polar coordinate system with the rotation center Ow of the workpiece W as the origin. In other words, the interference amount calculation unit 111 stores, as the outer peripheral surface shape of the workpiece W, a group of multiple line segments connecting division points (white dots in FIG. 4) on the outer peripheral surface obtained by dividing the workpiece W equiangularly (α) with the rotation center Ow (origin) of the workpiece W. The division points indicated by white dots in FIG. 4 are stored as the outer peripheral surface shape of the workpiece W before removal by the grinding wheel T.

[0046] The interference amount calculation unit 111 determines the intersections (black dots in FIG. 4) 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 (center 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 intersections (black dots in FIG. 4) as the outer peripheral surface shape of the workpiece W after it has been removed by the grinding wheel T. In other words, the interference amount calculation unit 111 changes the stored outer peripheral surface shape of the workpiece W.

[0047] The interference amount calculation unit 111 then subtracts the area of ​​a triangle △Ow-b1-b2 formed by points b1 and b2 (intersections with the grinding wheel T) after removal and the origin Ow from the area of ​​a triangle △Ow-a1-a2 formed by adjacent points a1 and a2 among the points defining the outer peripheral surface shape of the workpiece W before removal and the origin Ow. The areas after subtraction are calculated for all adjacent points that define the outer peripheral surface shape of the workpiece W.

[0048] The interference amount calculation unit 111 then adds up the areas after each subtraction and multiplies the total area by the thickness of the workpiece W to calculate the interference amount (removal amount). In the above, the area of ​​the portion to be removed is calculated by calculating the areas of two types of triangles and then calculating the difference between the areas. Alternatively, the area of ​​the portion to be removed may be calculated by directly calculating the quadrangle a1-a2-b1-b2.

[0049] 2, the grinding efficiency calculation unit 112 calculates the grinding efficiency Z' based on the amount of interference calculated by the interference amount calculation unit 111. The grinding efficiency Z' is calculated as the amount of interference per unit time, i.e., the volume of the workpiece W ground by the grinding wheel T in unit time.

[0050] 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 binder of the grinding wheel T, and the condition of the outer circumferential surface of the grinding wheel T. The condition of the outer circumferential surface of the grinding wheel T is expressed, for example, using an index that indicates the wear state and sharpness of the abrasive grains of the grinding wheel T. Here, the grinding characteristic determination unit 113 stores the grinding characteristics in each state in advance through experiments, analysis, etc.

[0051] Based on the grinding efficiency Z' and the grinding characteristic kc, 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. The grinding resistance Fn is obtained by multiplying the grinding efficiency Z' by the grinding characteristic kc (Fn = kc × Z').

[0052] The grinding characteristics kc have a substantially linear relationship such that the grinding resistance Fn in the normal direction (X-axis direction) increases as the grinding efficiency Z' increases. The grinding characteristics kc change in this relationship, for example, when the grinding wheel T is worn. For example, when the grinding wheel T is worn, the grinding resistance Fn in the normal direction changes to increase with respect to the grinding efficiency Z'.

[0053] The contact dynamic stiffness table storage unit 103 stores contact dynamic stiffness data Ci, Ki between the workpiece W and the grinding wheel T. In particular, the contact dynamic stiffness table storage unit 103 stores the correspondence between the machining conditions and the contact dynamic stiffness data Ci, Ki. The workpiece support dynamic stiffness table storage unit 104 stores workpiece support dynamic stiffness data Cw, Kw for the spindle unit 30 and tailstock unit 40, which serve as workpiece support devices. In particular, the workpiece support dynamic stiffness table storage unit 104 stores the correspondence between the machining conditions and the workpiece support dynamic stiffness data Cw, Kw. The grinding wheel support dynamic stiffness table storage unit 105 stores grinding wheel support dynamic stiffness data Ct, Kt (tool support dynamic stiffness data) for the wheel head body 51, which serves as the grinding wheel support device. In particular, the grinding wheel support dynamic stiffness table storage unit 105 stores the correspondence between the machining conditions and the grinding wheel support dynamic stiffness data Ct, Kt.

[0054] The contact dynamic stiffness, workpiece support dynamic stiffness, and grinding wheel support dynamic stiffness will be described with reference to Figure 5. The contact dynamic stiffness is the dynamic stiffness between the workpiece W and the grinding wheel T, and is the dynamic stiffness exerted by contact between the workpiece W and the grinding wheel T during grinding. The contact dynamic stiffness is defined by the damping coefficient Ci and the spring constant Ki. The damping coefficient Ci is a value that represents the relationship between the relative speed between the workpiece W and the grinding wheel T and the external force that the workpiece W or the grinding wheel T receives. The spring constant Ki is a value that represents the relationship between the relative position between the workpiece W and the grinding wheel T and the external force that the workpiece W or the grinding wheel T receives.

[0055] In particular, the contact dynamic stiffness corresponds to the contact arc length L where the grinding wheel T comes into contact with the workpiece W during grinding. As shown in Figure 3, the contact arc length L is the length of the arc of the outer surface of the grinding wheel T that comes into contact with the workpiece W during grinding, in a cross section perpendicular to the axis of the grinding wheel T. The contact arc length L varies depending on the feed rate of the grinding wheel T in the X-axis direction, the outer diameter of the grinding wheel T, the outer diameter of the workpiece W, etc.

[0056] Furthermore, the contact dynamic stiffness is caused by the elastic deformation of the grinding wheel T. That is, the contact dynamic stiffness is expressed by the spring constant caused by the elastic deformation of the grinding wheel T and the damping coefficient caused by the elastic deformation of the grinding wheel T.

[0057] The workpiece support dynamic stiffness is the dynamic stiffness related to support in the spindle unit 30 and tailstock unit 40, and is the dynamic stiffness exhibited when the workpiece W is supported by the spindle unit 30 and tailstock unit 40 as workpiece support devices that make up the grinding machine 2. The workpiece support dynamic stiffness is defined by the damping coefficient Cw and the spring constant Kw. The damping coefficient Cw is a value that represents the relationship between the relative speed of the workpiece W with respect to the reference positions of the spindle unit 30 and tailstock unit 40 and the external force that the workpiece W receives. The spring constant Kw is a value that represents the relationship between the relative position of the workpiece W with respect to the reference positions of the spindle unit 30 and tailstock unit 40 and the external force that the workpiece W receives.

[0058] The grinding wheel support dynamic stiffness is the dynamic stiffness related to support in the wheel head body 51, and is the dynamic stiffness exhibited when the grinding wheel T is supported by the wheel head body 51, which serves as a grinding wheel support device constituting the grinding machine 2. The grinding wheel support dynamic stiffness is defined by a damping coefficient Ct and a spring constant Kt. The damping coefficient Ct is a value that represents the relationship between the relative speed of the grinding wheel T with respect to a reference position on the wheel head body 51 and the external force that the grinding wheel T receives. The spring constant Kt is a value that represents the relationship between the relative position of the grinding wheel T with respect to a reference position on the wheel head body 51 and the external force that the grinding wheel T receives.

[0059] The contact dynamic stiffness table storage unit 103 will be described in detail with reference to Fig. 6 and Fig. 7. The contact dynamic stiffness table storage unit 103 stores a contact dynamic stiffness table including contact dynamic stiffness data Ci and Ki. Specifically, as shown in Fig. 6, the contact dynamic stiffness table is a table whose items are processing conditions, contact arc length L, mass Mi, damping coefficient Ci, and spring constant Ki. The contact dynamic stiffness table shown in Fig. 6 is a data table obtained by performing actual measurements, which will be described later.

[0060] In FIG. 6, the processing conditions include, for example, the feed rate of the grinding wheel T in the X-axis direction, the outer diameter of the grinding wheel T, and the outer diameter of the workpiece W. As described above, the contact arc length L is the length of the arc of the outer surface of the grinding wheel T that is in contact with the workpiece W during grinding in a cross section perpendicular to the axis of the grinding wheel T. The contact arc length L is determined from the feed rate of the grinding wheel T in the X-axis direction, the outer diameter of the grinding wheel T, the outer diameter of the workpiece W, and the like. The mass Mi includes mass information of the workpiece W and the grinding wheel T. The damping coefficient Ci and spring constant Ki exhibit different values ​​depending on the processing conditions, i.e., the contact arc length L.

[0061] Furthermore, in addition to the machining conditions that affect the contact arc length L, the machining conditions that affect the contact dynamic stiffness include the rotational speed of the grinding wheel T, the rotational speed of the workpiece W, and the amount of coolant. These mainly cause changes in the temperatures of the grinding wheel T and the workpiece W. In particular, if the binder of the grinding wheel T is temperature-dependent, the contact dynamic stiffness will change depending on the temperature of the grinding wheel T. Therefore, the contact dynamic stiffness table storage unit 103 has a table shown in the foreground of Fig. 6 for each machining condition that affects the temperature.

[0062] Here, the contact dynamic stiffness table shown in FIG. 6 is a data table obtained by performing actual measurements under the first machining conditions (condition 1, condition 2, condition 3, ...), and therefore the table is limited to the contact arc length L corresponding to the first machining condition under which the actual measurements were performed.

[0063] However, since the machining conditions actually used are diverse, the contact dynamic stiffness table shown in Fig. 6 may not be sufficient. Therefore, as shown in Fig. 7, a contact dynamic stiffness table based on actual measurements is used to supplement the table by performing interpolation processing.

[0064] 6, the contact dynamic stiffness table storage unit 103 stores in advance the correspondence between the first processing conditions (condition 1, condition 2, condition 3, ...) and the actually measured contact dynamic stiffness data. Then, by performing an interpolation process using the contact dynamic stiffness data for the first processing conditions (condition 1, condition 2, condition 3, ...), contact dynamic stiffness data for second processing conditions (condition 1h, condition 2h, condition 3h) different from the first processing conditions is generated. Then, the contact dynamic stiffness table storage unit 103 additionally stores the generated contact dynamic stiffness data.

[0065] The interpolation process may use, for example, an empirical formula that defines the relationship between the contact arc length L, the damping coefficient Ci, and the spring constant Ki. Alternatively, the interpolation process may use machine learning or theoretical calculation.

[0066] As described above, the contact arc length L is determined by the feed rate of the grinding wheel T in the X-axis direction, the outer diameter of the grinding wheel T, the outer diameter of the workpiece W, etc. However, the contact arc length L changes due to deflection of the workpiece W and the grinding wheel T during grinding. Therefore, even under the same machining conditions, the contact arc length L may vary depending on the amount of deflection of the workpiece W and the grinding wheel T, etc. Therefore, it is preferable that the contact dynamic stiffness table storage unit 103 stores contact dynamic stiffness data Ci, Ki for a large number of contact arc lengths L.

[0067] The workpiece support dynamic stiffness table storage unit 104 will be described in detail with reference to Fig. 8. The workpiece support dynamic stiffness table storage unit 104 stores workpiece support dynamic stiffness data Cw, Kw. Specifically, as shown in Fig. 8, the workpiece support dynamic stiffness table is a table having the following items: machining conditions (condition 21, condition 22, condition 23, ...), mass Mw, damping coefficient Cw, and spring constant Kw.

[0068] For example, in a case where the tailstock center 41 can control the pressing force applied to the workpiece W in the axial direction of the workpiece W, the machining condition in Fig. 8 is the pressing force applied by the tailstock center 41. The workpiece support dynamic stiffness data Cw, Kw is data that changes in accordance with changes in the contact state between the tailstock center 41 and the workpiece W due to changes in the pressing force applied by the tailstock center 41. Therefore, the workpiece support dynamic stiffness table storage unit 104 stores the mass Mw, damping coefficient Cw, and spring constant Kw for each of a plurality of pressing forces applied by the tailstock center 41.

[0069] The workpiece support dynamic stiffness data Cw, Kw can be obtained, for example, by conducting a hammering test in a state in which the workpiece W is supported by the spindle center 34 and the tailstock center 41. Furthermore, by conducting a hammering test while changing the pressing force of the tailstock center 41, the workpiece support dynamic stiffness data Cw, Kw shown in Fig. 8 can be obtained. Furthermore, the workpiece support dynamic stiffness table storage unit 104 has a table shown in the foreground of Fig. 8 for each type of workpiece W.

[0070] As described above, the grinding wheel support dynamic stiffness table storage unit 105 stores the grinding wheel support dynamic stiffness data Ct, Kt. The grinding wheel support dynamic stiffness table storage unit 105 stores, for example, the grinding wheel support dynamic stiffness data Ct, Kt for each type of grinding wheel T. Furthermore, in a configuration in which the grinding wheel T is supported by a hydrostatic bearing, if the pressure of the hydrostatic bearing is controllable, the grinding wheel support dynamic stiffness data Ct, Kt may be data that changes depending on the pressure of the hydrostatic bearing. Therefore, the grinding wheel support dynamic stiffness table storage unit 105 may store the mass Mt, damping coefficient Ct, and spring constant Kt depending on the pressure of the hydrostatic bearing as a processing condition.

[0071] 2, the machining condition acquisition unit 106 acquires the machining conditions used when grinding is performed by the grinding machine 2. More specifically, the machining condition acquisition unit 106 acquires the machining conditions used at the time of estimation by the estimation unit 102. The machining conditions acquired by the machining condition acquisition unit 106 are information used by the dynamic stiffness determination unit 107 to calculate each dynamic stiffness. The acquired machining conditions include, for example, the outer diameter of the workpiece W, the outer diameter of the grinding wheel T, the feed rate of the grinding wheel T in the X-axis direction, the rotational speed of the grinding wheel T, the rotational speed of the workpiece W, the amount of coolant, the pressing force of the tailstock center 41, and the pressure of the hydrostatic bearing of the grinding wheel T.

[0072] When the processing estimation device 3 is a simulation device independent of the grinding machine 2, the processing condition acquisition unit 106 acquires the processing conditions included in the grinding program by inputting the grinding program. When the processing estimation device 3 functions as a simulation device that operates in conjunction with the grinding process by the grinding machine 2, the processing condition acquisition unit 106 may acquire the processing conditions by inputting the grinding program from the control device 70, or may acquire information on the processing conditions directly from the control device 70 of the grinding machine 2.

[0073] The dynamic stiffness determination unit 107 determines dynamic stiffness data that affects the grinding process. The dynamic stiffness determination unit 107 separately determines contact dynamic stiffness data, workpiece support dynamic stiffness data, and grinding wheel support dynamic stiffness data. That is, the dynamic stiffness determination unit 107 includes a contact dynamic stiffness determination unit 121, a workpiece support dynamic stiffness determination unit 122, and a grinding wheel support dynamic stiffness determination unit 123.

[0074] The contact dynamic stiffness determination unit 121 acquires the contact dynamic stiffness table stored in the contact dynamic stiffness table storage unit 103 and the machining conditions acquired by the machining condition acquisition unit 106. Then, the contact dynamic stiffness determination unit 121 determines the contact dynamic stiffness data Ci, Ki corresponding to the acquired machining conditions from the contact dynamic stiffness table.

[0075] The contact arc length L also changes depending on the outer peripheral surface shape of the workpiece W that changes during grinding, and the deflection of the workpiece W and grinding wheel T that occurs due to grinding resistance. The outer peripheral surface shape of the workpiece W and the relative position between the workpiece W and the grinding wheel T during grinding are successively calculated by the interference amount calculation unit 111 of the estimation unit 102.

[0076] Therefore, the contact dynamic stiffness determiner 121 can also obtain the outer peripheral surface shape of the workpiece W at the current time in the simulation and the relative position between the workpiece W and the grinding wheel T from the interference amount calculator 111, and calculate the contact arc length L. Then, the contact dynamic stiffness determiner 121 can determine the contact dynamic stiffness data Ci, Ki corresponding to the calculated contact arc length L from the contact dynamic stiffness table.

[0077] The workpiece support dynamic stiffness determination unit 122 acquires the workpiece support dynamic stiffness table stored in the workpiece support dynamic stiffness table storage unit 104 and the machining conditions acquired by the machining condition acquisition unit 106. Then, the workpiece support dynamic stiffness determination unit 122 determines workpiece support dynamic stiffness data Cw, Kw corresponding to the acquired machining conditions from the workpiece support dynamic stiffness table.

[0078] The grinding wheel support dynamic stiffness determination unit 123 acquires the grinding wheel support dynamic stiffness table stored in the grinding wheel support dynamic stiffness table storage unit 105 and the machining conditions acquired by the machining condition acquisition unit 106. Then, the grinding wheel support dynamic stiffness determination unit 123 determines the grinding wheel support dynamic stiffness data Ct, Kt corresponding to the acquired machining conditions from the grinding wheel support dynamic stiffness table.

[0079] The correction amount calculation unit 108 calculates the correction amount for the relative displacement of the grinding wheel T and workpiece W in the X-axis direction caused by the grinding force Fn, based on each dynamic stiffness data determined by the dynamic stiffness determination unit 107. The correction amount for the displacement can be found from each dynamic stiffness data and the grinding force Fn. In other words, the correction amount for the displacement can be calculated from the grinding force Fn, contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt.

[0080] The correction amount calculation unit 108 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, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T acquired by the command value acquisition unit 101. However, due to the grinding resistance Fn, the relative position between the workpiece W and the grinding wheel T will be different from the relative position determined by the command value.

[0081] Therefore, when estimating the estimation target, the estimation unit 102 uses, as the relative position between the workpiece W and the grinding wheel T, the relative position obtained by adding the correction amount calculated by the correction amount calculation unit 108 to the relative position acquired by the command value acquisition unit 101. In other words, the estimation unit 102 estimates the estimation target based on the relative position according to the command value and the correction amount calculated using each dynamic stiffness data.

[0082] In particular, in this embodiment, the correction amount calculation unit 108 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 amount of interference between the workpiece W and the grinding wheel T 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 acquired by the command value acquisition unit 101. However, due to the grinding resistance Fn, the relative position between the workpiece W and the grinding wheel T will be different from the relative position determined by the command value.

[0083] Therefore, the interference amount calculation unit 111 uses the relative position between the workpiece W and the grinding wheel T used to calculate the amount of interference, which is the sum of the relative position acquired by the command value acquisition unit 101 and the correction amount calculated by the correction amount calculation unit 108. In other words, the interference amount calculation unit 111 calculates the amount of interference based on the relative position determined by the command value and the correction amount calculated using each dynamic stiffness data.

[0084] The interference amount calculation unit 111 calculates the amount of interference taking the amount of correction into consideration, and the grinding efficiency calculation unit 112, grinding characteristic determination unit 113, and grinding resistance calculation unit 114 obtain the grinding efficiency Z', grinding characteristic kc, and grinding resistance Fn based on the amount of interference taking the amount of correction into consideration.

[0085] The output unit 109 outputs the estimation target estimated by the estimation unit 102. That is, the output unit 109 estimates at least one 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 grinding machine 2. The output unit 109 may, for example, teach the estimation result to a teaching device (not shown). The output unit 109 can also output the estimation result to the control device 70 of the grinding machine 2. In this case, the control device 70 can use the estimation result to correct the grinding conditions, for example.

[0086] 4. Contact dynamic stiffness data acquisition and processing The contact dynamic stiffness data acquisition process will be described with reference to Figs. 9 to 11. As shown in Fig. 9, in the contact dynamic stiffness data acquisition process, first, the measuring jig 4 is attached to the grinding machine 2 and the workpiece W (S1). The measuring jig 4 is a non-contact vibrator, and is a device that applies a vibration force to the workpiece W. As shown in Fig. 10, the measuring jig 4 is provided on the upper surface of the table 20. The fixed position of the measuring jig 4 in the Z-axis direction on the upper surface of the table 20 can be adjusted.

[0087] The measuring jig 4 holds the workpiece W with the workpiece W inserted therethrough. In detail, a part of the shank Wa, which is the non-machined portion of the workpiece W, is inserted into the measuring jig 4, and a plurality of machined portions Wb to be ground are located outside the measuring jig 4. The workpiece W inserted and held in the measuring jig 4 is supported by the spindle device 30 and tailstock device 40, in the same manner as during normal grinding.

[0088] Here, the configuration of the measuring jig 4 will be described with reference to Figures 11(a) to 11(c). The measuring jig 4 includes a housing 131, an electromagnet 132, a rotor 133, a lock nut 134, a displacement sensor 135, and a control device 136. The housing 131 is fixed to the upper surface of the table 20 of the grinding machine 2. Furthermore, the housing 131 is formed with a hole 131a that penetrates in the Z-axis direction.

[0089] The electromagnet 132 is embedded in the housing 131. The rotor 133 is attached to the outer circumferential surface of the workpiece W and is provided integrally with the workpiece W. The rotor 133 is made of a magnetic material and moves by the magnetic force generated by the electromagnet 132. The rotor 133 is formed in a cylindrical shape, and the outer circumferential surface of the rotor 133 is disposed with a predetermined gap relative to the inner circumferential surface of the housing 131. This gap determines the distance the rotor 133 can move relative to the housing 131. The inner circumferential surface of the rotor 133 is formed according to the shape of the outer circumferential surface of the workpiece W. The lock nut 134 is a member for fixing the rotor 133 to the workpiece W. The method of fixing the rotor 133 is not limited to a method using the lock nut 134, and various means can be used.

[0090] Displacement sensor 135 is provided at a position close to the inner circumferential surface of housing 131, and measures the distance from the outer circumferential surface of rotor 133. In other words, when rotor 133 is vibrated by electromagnet 132, displacement sensor 135 measures the displacement of rotor 133 in the direction in which rotor 133 approaches or moves away from the inner circumferential surface of housing 131 (hereinafter referred to as radial displacement).

[0091] 11(c), the control device 136 supplies a driving current to the electromagnet 132 so that the electromagnet 132 applies an excitation force. The control device 136 also acquires the displacement measured by the displacement sensor 135, i.e., the radial displacement of the rotor 133.

[0092] 9, the shaft portion Wa, which is the non-machined portion of the workpiece W, is inserted into the rotor 133 of the measuring jig 4 as shown in FIG. 11(a). Then, the rotor 133 is fixed to the workpiece W with a lock nut 134 as shown in FIG. 11(b).

[0093] Then, the housing 131 of the measuring jig 4 is attached to the table 20. Furthermore, the workpiece W to which the rotor 133 is attached is supported by the spindle unit 30 and the tailstock unit 40. At this time, the position of the housing 131 is adjusted so that the outer peripheral surface of the rotor 133 faces the inner peripheral surface of the housing 131 of the measuring jig 4, as shown in FIG. 11(b).

[0094] Next, grinding is started (S2). That is, while the workpiece W and the grinding wheel T are rotating, the grinding wheel T is moved in the X-axis direction to grind the outer peripheral surface of the processing portion Wb of the workpiece W.

[0095] Next, an excitation force is applied by the measuring jig 4 (S3). The application of the excitation force by the measuring jig 4 is performed while the workpiece W is being ground by the grinding wheel T. The applied excitation force may be impulse excitation or sweep excitation in which the excitation frequency is continuously changed. The application of the excitation force is performed by the control device 136 of the measuring jig 4 supplying a current to the electromagnet 132. The excitation force is controlled by the current supplied to the electromagnet 132 by the control device 136.

[0096] Next, when an excitation force is applied during grinding, the radial displacement of the rotor 133 is measured by the displacement sensor 135 of the measuring jig 4 (S4). Here, the displacement of the rotor 133 coincides with the radial displacement of the portion of the workpiece W that is fixed to the rotor 133. Therefore, the displacement sensor 135 of the measuring jig 4 measures the radial displacement that occurs in the workpiece W when an excitation force is applied to the workpiece W.

[0097] Next, when the measurement by the displacement sensor 135 is completed, the grinding process is ended (S5).

[0098] Next, the overall dynamic stiffness data Ccom, Kcom during grinding is calculated (S6). The overall dynamic stiffness data Ccom, Kcom is overall (composite) dynamic stiffness data represented by the above-mentioned contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt. The overall dynamic stiffness data Ccom, Kcom is represented as the sum of the above-mentioned contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt.

[0099] As described above, the radial displacement measured by the displacement sensor 135 of the measuring jig 4 is measured when an excitation force is applied to the workpiece W during grinding. Therefore, the measured displacement is affected by the contact dynamic stiffness data Ci, Ki, the workpiece support dynamic stiffness data Cw, Kw, and the grinding wheel support dynamic stiffness data Ct, Kt. Therefore, the calculation of the overall dynamic stiffness data Ccom, Kcom is data generated from the relationship between the excitation force and the radial displacement of the workpiece W when an excitation force is applied to the workpiece W during grinding.

[0100] Next, workpiece support dynamic stiffness data Cw, Kw and grinding wheel support dynamic stiffness data Ct, Kt are obtained (S7). The workpiece support dynamic stiffness data Cw, Kw and grinding wheel support dynamic stiffness data Ct, Kt are obtained in advance by a hammering test or the like.

[0101] Next, the contact dynamic stiffness data Ci, Ki are calculated (S8). The contact dynamic stiffness data Ci, Ki are obtained by subtracting the workpiece support dynamic stiffness data Cw, Kw and the grinding wheel support dynamic stiffness data Ct, Kt from the overall dynamic stiffness data Ccom, Kcom.

[0102] Next, the contact dynamic stiffness data Ci, Ki are interpolated (S9). The interpolation process is as described above with reference to FIG. 7. In other words, the interpolation process is a process in which the contact dynamic stiffness data Ci, Ki obtained by actual measurement is used to obtain contact dynamic stiffness data Ci, Ki under grinding conditions different from those of the actual measurement. The interpolation process can be performed using an empirical formula, machine learning, theoretical calculation, or the like. In this way, the contact dynamic stiffness data Ci, Ki as shown in FIG. 7 can be obtained.

[0103] 5.Effects In this embodiment, the dynamic contact stiffness data Ci and Ki are used to estimate at least one 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 grinding machine 2. The dynamic contact stiffness data Ci and Ki are represented by the spring constant Ki and damping coefficient Ci between the workpiece W and the grinding wheel T exerted by contact between the workpiece W and the grinding wheel T. In this way, by using the dynamic contact stiffness data Ci and Ki including the spring constant Ki and damping coefficient Ci, various estimation targets can be estimated with high accuracy. Note that static contact stiffness data, which is distinguished from dynamic contact stiffness data, is represented only by the spring constant K and does not include the damping coefficient C.

[0104] In particular, the contact dynamic stiffness data Ci, Ki are data resulting from the elastic deformation of the grinding wheel T, and also data corresponding to the contact arc length L of the grinding wheel T contacting the workpiece W during grinding. When the grinding wheel T is significantly affected by the elastic deformation, the estimation target can be estimated with high accuracy by using the contact dynamic stiffness data Ci, Ki as described above.

[0105] 9, the contact dynamic stiffness data Ci, Ki are data generated from the relationship between the excitation force and the displacement of the workpiece W when an excitation force is applied to the workpiece W while the workpiece W is being ground by the grinding wheel T. This makes it possible to reliably obtain the contact dynamic stiffness data Ci, Ki during grinding.

[0106] 6 and 7, the contact dynamic stiffness table storage unit 103 stores in advance a contact dynamic stiffness table that represents the correspondence between the contact dynamic stiffness data Ci and Ki and the machining conditions, including at least one of the relative position between the workpiece W and the grinding wheel T, the rotational speed of the grinding wheel T, and the rotational speed of the workpiece W. The estimation unit 102 then estimates the estimation target during grinding using the machining conditions at the time of estimation and the correspondence stored in the contact dynamic stiffness table storage unit 103. In this way, by storing in advance the relationships between the contact dynamic stiffness data Ci and Ki and various machining conditions, the estimation target can be estimated with high accuracy using the contact dynamic stiffness data Ci and Ki that correspond to the machining conditions used for actual estimation.

[0107] 7, by performing interpolation processing, contact dynamic stiffness data Ci, Ki for a second machining condition that is different from the first machining condition in actual measurement is additionally stored in the contact dynamic stiffness table storage unit 103. In this way, contact dynamic stiffness data Ci, Ki for the second machining condition that is not actually measured can be generated, and the estimation target can be estimated with high accuracy.

[0108] The correction amount calculation unit 108 calculates the correction amount using the workpiece support dynamic stiffness data Cw, Kw and grinding wheel support dynamic stiffness data Ct, Kt in addition to the contact dynamic stiffness data Ci, Ki. The estimation unit 102 then estimates the estimation target using the correction amount calculated using the contact dynamic stiffness data Ci, Ki, the workpiece support dynamic stiffness data Cw, Kw and the grinding wheel support dynamic stiffness data Ct, Kt. In this way, not only is dynamic stiffness data used for contact stiffness, but dynamic stiffness data is also used for the workpiece support stiffness and grinding wheel support stiffness. Therefore, the estimation target can be estimated with high accuracy.

[0109] 2, the dynamic stiffness determination unit 107 of the machining estimation device 3 separately determines contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt. In particular, the machining estimation device 3 stores target dynamic stiffness data in a contact dynamic stiffness table storage unit 103, a workpiece support dynamic stiffness table storage unit 104, and a grinding wheel support dynamic stiffness table storage unit 105. The correction amount calculation unit 108 then calculates the correction amount using the separately determined contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt.

[0110] In this way, the contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt are stored separately and processed for determination, thereby enhancing versatility. For example, when the type of workpiece W is changed, the grinding wheel support dynamic stiffness data Ct, Kt can be used as is without change. Furthermore, when the pressing force of the tailstock center 41 is changed, it is sufficient to change only the workpiece support dynamic stiffness data Cw, Kw.

[0111] Furthermore, in a cylindrical grinding machine configured to support the other axial end of the workpiece W by a tailstock center 41, the tailstock center 41 may be configured to be able to control the pressing force of the tailstock center 41 in the axial direction of the workpiece W. In this case, the workpiece support dynamic stiffness data Cw, Kw are data that change in accordance with changes in the contact state between the tailstock center 41 and the workpiece W due to changes in the pressing force of the tailstock center 41. In other words, by setting the workpiece support dynamic stiffness data Cw, Kw to data that takes into account the pressing force of the tailstock center 41, it is possible to estimate the estimation target with higher accuracy.

[0112] (Embodiment 2) The processing estimation device 5 of the second embodiment will be described with reference to Fig. 12 and Fig. 13. Here, the processing estimation device 5 differs from the processing estimation device 3 of the first embodiment in the dynamic stiffness determination unit 207 and the overall dynamic stiffness table storage unit 203. The other configurations of the processing estimation device 5 are the same as those of the first embodiment.

[0113] The overall dynamic stiffness table storage unit 203 stores overall dynamic stiffness data Ccom, Kcom. In particular, the overall dynamic stiffness table storage unit 203 stores the correspondence between the machining conditions and the overall dynamic stiffness data Ccom, Kcom. The overall dynamic stiffness data Ccom, Kcom is as described in the contact dynamic stiffness data acquisition process in embodiment 1. In other words, the overall dynamic stiffness data Ccom, Kcom is overall (composite) dynamic stiffness data represented by the contact dynamic stiffness data Ci, Ki, workpiece support dynamic stiffness data Cw, Kw, and grinding wheel support dynamic stiffness data Ct, Kt.

[0114] The dynamic stiffness determination unit 207 determines dynamic stiffness data that affects the grinding process. In this embodiment, the dynamic stiffness determination unit 207 includes an overall dynamic stiffness determination unit 221. The overall dynamic stiffness determination unit 221 determines overall dynamic stiffness data Ccom, Kcom that combines the contact dynamic stiffness data Ci, Ki, the workpiece support dynamic stiffness data Cw, Kw, and the grinding wheel support dynamic stiffness data Ct, Kt.

[0115] The overall dynamic stiffness determination unit 221 acquires the overall dynamic stiffness table stored in the overall dynamic stiffness table storage unit 203 and the processing conditions acquired by the processing condition acquisition unit 106. Then, the overall dynamic stiffness determination unit 221 determines the overall dynamic stiffness data Ccom, Kcom corresponding to the acquired processing conditions from the overall dynamic stiffness table.

[0116] According to this embodiment, the estimation target can be estimated with high accuracy by using the overall dynamic stiffness data Ccom, Kcom, which are a combination of the contact dynamic stiffness data Ci, Ki, the workpiece support dynamic stiffness data Cw, Kw, and the grinding wheel support dynamic stiffness data Ct, Kt. However, if there are many types of workpieces W and grinding wheels T, many machining conditions, or many pressing forces controlled by the tailstock center 41, the overall dynamic stiffness table may contain a large amount of data. In such cases, it is preferable to process each dynamic stiffness data separately, as in the first embodiment.

[0117] (Embodiment 3) A processing estimation system 301 of this embodiment will be described with reference to Fig. 14. The processing estimation system 301 targets cutting processing using a lathe 302. The processing estimation system 301 includes the lathe 302 as a processing device and a processing estimation device 303.

[0118] The lathe 302 turns the workpiece W by rotating the workpiece W and moving the cutting tool T2 relative to the workpiece W. The processing estimation device 303 estimates at least one of the state of the workpiece W or the cutting tool T2 during cutting processing on the lathe 302, the shape of the workpiece W, the shape of the cutting tool T2, and the mechanical state of the lathe 302. The processing estimation device 303 performs estimation processing of the above-mentioned estimation target by inputting information used in cutting processing and performing a simulation.

[0119] The lathe 302 includes, for example, a bed 310, a spindle unit 320, a tailstock unit 330, a rest unit 340, a tool table 350, and a control unit 360. The spindle unit 320 constitutes a workpiece support device. The spindle unit 320 is fixed to the upper surface of the bed 310, supports one end of the workpiece W, and drives the workpiece W to rotate. The spindle unit 320 includes a spindle housing 321, a spindle 322, a spindle motor 323, a chuck 324, a spindle detector 325, and a spindle drive circuit (not shown).

[0120] Spindle housing 321 is fixed onto bed 310. Spindle 322 is rotatably supported by spindle housing 321 via bearings. Spindle motor 323 rotates and drives spindle 322. Chuck 324 is fixed to spindle 322 and grips one end of workpiece W. Spindle detector 325 and a spindle drive circuit are provided to drive spindle motor 323.

[0121] The tailstock device 330, together with the spindle device 320, constitutes a workpiece support device. The tailstock device 330 is disposed on the bed 310 so as to face the spindle device 320 in the Z-axis direction. The tailstock device 330 is provided on the bed 310 so as to be movable in the Z-axis direction. The tailstock device 330 includes a tailstock center 331 that supports the other end of the workpiece W.

[0122] The rest device 340 is fixed on the bed 310 and supports the outer peripheral surface of the axially intermediate portion of the workpiece W. In particular, the rest device 340 is disposed at a position where the workpiece W can resist the cutting load received from the cutting tool T2.

[0123] Tool table 350 includes Z-axis slide table 351, X-axis slide table 352, turret (swivel-type tool rest) 353, and a plurality of cutting tools T2. Z-axis slide table 351 is supported on Z-axis guide surface 311 of bed 310 so as to be movable in the Z-axis direction, and is moved in the Z-axis direction by Z-axis drive mechanism 312 provided on bed 310.

[0124] X-axis slide base 352 is supported on X-axis guide surface 351a on Z-axis slide base 351 so as to be movable in the X-axis direction, and is moved in the X-axis direction by X-axis drive mechanism 351b provided on Z-axis slide base 351. Turret 353 is provided on X-axis slide base 352 so as to be rotatable around an axis parallel to the Z-axis direction. Multiple cutting tools T2 are fixed to the outer circumferential surface of turret 353. The multiple cutting tools T2 may be different types of tools.

[0125] The control device 360 ​​is a CNC (Computer Numerical Control) device that controls machining. The control device 360 ​​is a Z-axis drive mechanism 312 and an X-axis drive mechanism 351b, which serve as moving devices, based on a cutting program, to control the position of the cutting tool T2. In other words, the control device 360 ​​controls the positions of the cutting tool T2 and the like, thereby moving the workpiece W and the cutting tool T2 relative to each other. Furthermore, the control device 360 ​​controls the rotation of the spindle 322 and the turret 353.

[0126] The processing estimation device 303 of this embodiment has the same configuration as the processing estimation device 3 of the first embodiment shown in Fig. 2. However, the grinding in the first embodiment is changed to cutting, and the grinding wheel T is changed to a cutting tool T2.

[0127] Next, the contact dynamic stiffness, workpiece support dynamic stiffness, and tool support dynamic stiffness in this embodiment will be described with reference to FIG. 15. The contact dynamic stiffness is the dynamic stiffness between the workpiece W and the cutting tool T2, and is the dynamic stiffness exerted by contact between the workpiece W and the cutting tool T2 during cutting. The contact dynamic stiffness is defined by a damping coefficient Ci and a spring constant Ki. The damping coefficient Ci is a value that represents the relationship between the relative speed between the workpiece W and the cutting tool T2 and the external force that the workpiece W or the cutting tool T2 receives. The spring constant Ki is a value that represents the relationship between the relative position between the workpiece W and the cutting tool T2 and the external force that the workpiece W or the cutting tool T2 receives.

[0128] In particular, the contact dynamic stiffness corresponds to the contact length L of the cutting tool T2 that comes into contact with the workpiece W during cutting. The contact length L varies depending on the size of the cutting tool T2, the tip shape of the cutting tool T2, the rake angle and clearance angle of the cutting tool T2, the cutting depth, the outer diameter of the workpiece W, etc.

[0129] The workpiece support dynamic stiffness is the dynamic stiffness related to support in the spindle unit 320, tailstock unit 330, and rest unit 340, and is the dynamic stiffness exhibited when the workpiece W is supported by the spindle unit 320, tailstock unit 330, and rest unit 340, which are workpiece support devices that make up the lathe 302. The workpiece support dynamic stiffness is defined by a damping coefficient Cw and a spring constant Kw. The damping coefficient Cw is a value that represents the relationship between the relative speed of the workpiece W with respect to the reference positions of the spindle unit 320, tailstock unit 330, and rest unit 340, and the external force that the workpiece W receives. The spring constant Kw is a value that represents the relationship between the relative position of the workpiece W with respect to the reference positions of the spindle unit 320, tailstock unit 330, and rest unit 340, and the external force that the workpiece W receives.

[0130] The tool support dynamic stiffness is the dynamic stiffness related to support on the tool table 350, and is the dynamic stiffness exhibited when the cutting tool T2 is supported by the tool table 350, which serves as a tool support device constituting the lathe 302. The tool support dynamic stiffness is defined by a damping coefficient Ct and a spring constant Kt. The damping coefficient Ct is a value that represents the relationship between the relative speed of the cutting tool T2 with respect to a reference position on the tool table 350 and the external force that the cutting tool T2 receives. The spring constant Kt is a value that represents the relationship between the relative position of the cutting tool T2 with respect to the reference position on the tool table 350 and the external force that the cutting tool T2 receives.

[0131] The processing estimation system 301 in this embodiment has the same effects as the processing estimation system 1 in the first embodiment.

[0132] (others) In the above embodiment, examples have been described in which grinding is performed using the grinding machine 2 and cutting is performed using the lathe 302. In addition to these, cutting can also be performed using a machining center.

Claims

1. In a processing device (2, 302) that processes a workpiece (W) using a grinding wheel (T) that is a tool, at least one of a state of the workpiece or the tool during processing, a shape of the workpiece, a shape of the tool, and a mechanical state of the processing device is estimated using contact dynamic stiffness data (Ci, Ki) between the workpiece and the tool that is exerted by contact between the workpiece and the tool during processing; The contact dynamic stiffness data is data generated from a relationship between an excitation force and a displacement of the workpiece when an excitation force is applied to the workpiece while the workpiece is being machined by the tool, A processing estimation device (3, 5, 303) that obtains data resulting from the elastic deformation of the grinding wheel and corresponding to the contact arc length (L) of the grinding wheel contacting the workpiece during grinding.

2. a contact dynamic stiffness table storage unit (103) that stores in advance a correspondence relationship between the contact dynamic stiffness data and machining conditions including at least one of the relative position between the workpiece and the tool, the rotational speed of the tool which is a rotating body, and the rotational speed of the workpiece; an estimation unit (102) that estimates at least one of a state of the workpiece or the tool during machining, a shape of the workpiece, a shape of the tool, and a mechanical state of the machining device, using the machining conditions at the time of estimation and the correspondence stored in the contact dynamic stiffness table storage unit; The processing estimation device (3, 303) according to claim 1, comprising:

3. the contact dynamic stiffness data; Workpiece support dynamic stiffness data (Cw, Kw) of the workpiece support device constituting the processing apparatus, which is exerted when the workpiece is supported by the workpiece support device; and Using tool support dynamic stiffness data (Ct, Kt) of the tool support device that is included in the processing apparatus and that is exerted when the tool is supported by the tool support device, 3. The machining estimation device (3, 5, 303) according to claim 1 or 2, which estimates at least one of a state of the workpiece or the tool during machining, a shape of the workpiece, a shape of the tool, and a mechanical state of the machining device.

4. A processing estimation device (3, 303) for processing a workpiece (W) with a tool (T, T2) in a processing device (2, 302) that uses contact dynamic stiffness data (Ci, Ki) between the workpiece and the tool that is exerted by contact between the workpiece and the tool during processing to estimate at least one of the state of the workpiece or the tool, the shape of the workpiece, the shape of the tool, and the mechanical state of the processing device, The contact dynamic stiffness data is data generated from the relationship between an excitation force and a displacement of the workpiece when an excitation force is applied to the workpiece while the workpiece is being machined by the tool. The processing estimation device includes: a contact dynamic stiffness table storage unit (103) that stores in advance a correspondence relationship between the contact dynamic stiffness data and machining conditions including at least one of the relative position between the workpiece and the tool, the rotational speed of the tool which is a rotating body, and the rotational speed of the workpiece; an estimation unit (102) that estimates at least one of a state of the workpiece or the tool during machining, a shape of the workpiece, a shape of the tool, and a mechanical state of the machining device, using the machining conditions at the time of estimation and the correspondence stored in the contact dynamic stiffness table storage unit; A processing estimation device (3, 303) comprising:

5. The contact dynamic stiffness table storage unit a correspondence relationship between a first machining condition that is the machining condition and the contact dynamic stiffness data actually measured under the first machining condition is stored in advance; The machining estimation device (3, 303) according to claim 4 further stores the contact dynamic stiffness data acquired for a second machining condition, which is a machining condition different from the first machining condition, by performing an interpolation process using the contact dynamic stiffness data for the first machining condition.

6. A processing estimation device (3, 5, 303) for processing a workpiece (W) with a tool (T, T2) in a processing device (2, 302) that uses contact dynamic stiffness data (Ci, Ki) between the workpiece and the tool that is exerted by contact between the workpiece and the tool during processing to estimate at least one of the state of the workpiece or the tool, the shape of the workpiece, the shape of the tool, and the mechanical state of the processing device, the contact dynamic stiffness data is data generated from a relationship between an excitation force and a displacement of the workpiece when an excitation force is applied to the workpiece while the workpiece is being machined by the tool, The processing estimation device includes: the contact dynamic stiffness data; Workpiece support dynamic stiffness data (Cw, Kw) of the workpiece support device constituting the processing apparatus, which is exerted when the workpiece is supported by the workpiece support device; and Using tool support dynamic stiffness data (Ct, Kt) of the tool support device that is included in the processing apparatus and that is exerted when the tool is supported by the tool support device, a machining estimation device (3, 5, 303) that estimates at least one of the state of the workpiece or the tool during machining, the shape of the workpiece, the shape of the tool, and the machine state of the machining device;

7. 7. The machining estimation device (3, 303) according to claim 6, wherein the contact dynamic stiffness data, the workpiece support dynamic stiffness data, and the tool support dynamic stiffness data are data determined separately.

8. 7. The machining estimation device (5, 303) according to claim 6, wherein the contact dynamic stiffness data, the workpiece support dynamic stiffness data, and the tool support dynamic stiffness data are determined as a combined total dynamic stiffness data (Ccom, Kcom).

9. The processing device (2) is a cylindrical grinding machine that grinds the cylindrical outer peripheral surface of the workpiece using the grinding wheel that is the tool, The machining estimation device (3, 5) according to any one of claims 6 to 8, wherein the workpiece support device is composed of a spindle device (30) that supports one axial end of the workpiece and rotates it, and a tailstock center (41) that supports the other axial end of the workpiece.

10. the tailstock center is configured to be able to control a pressing force applied to the workpiece in an axial direction of the workpiece, 10. The machining estimation device (3, 5) according to claim 9, wherein the workpiece support dynamic stiffness data is data that changes in accordance with a change in the contact state between the tailstock center and the workpiece due to a change in the pressing force by the tailstock center.

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