Workpiece quality determination device, machining estimation device, and machining system

Abstract

The invention relates to a workpiece quality determination device, a machining estimation device, and a machining system. A workpiece quality determination device (131) for calculating a workpiece quality (M'w (Z ')) for analyzing dynamic characteristics during machining in a machining device (2) for machining a workpiece (W) by means of a tool (T), the workpiece quality determination device (131) being provided with: a first correspondence relationship storage unit (103b) for storing a first correspondence relationship between the first correspondence relationship storage unit (103b) and a second correspondence relationship storage unit (103b) for storing a second correspondence relationship between the first correspondence relationship storage unit (103b); a mass correspondence relationship storage unit that stores a mass correspondence relationship, which is a correspondence relationship between a machining state index (Z ') that varies in accordance with the state of machining of the workpiece (W) by the tool (T) and the analyzed workpiece mass (M'w (Z')); a machining state index acquisition unit (125) that acquires the machining state index (Z '); and a workpiece quality determination unit (122) that determines the workpiece quality (M'w (Z ')) for analysis on the basis of the acquired machining state index (Z') and the quality correspondence relationship.

Description

Technical Field

[0001] The present invention relates to a workpiece quality determination device, a machining inference device, and a machining system. Background Art

[0002] In a grinding device that grinds a workpiece with a grinding wheel, in order to accurately infer the machining result, it is necessary to correct the relative position between the workpiece and the grinding wheel during the inference process. In the structure disclosed in Patent Document 1, when grinding a workpiece with a grinding wheel, in addition to the grinding resistance, the support rigidity of the workpiece, the support rigidity of the grinding wheel, and the contact static rigidity between the workpiece and the grinding wheel are considered, and the relative position between the workpiece and the grinding wheel is corrected with high precision, and the machining result of the workpiece is inferred. The contact static rigidity used here is not the value measured when the grinding wheel is stationary, but is calculated using the theoretical contact static rigidity during grinding. The contact static rigidity is represented by the spring constant K between the workpiece and the grinding wheel. Moreover, the workpiece quality in the analysis is used as a fixed value, which is calculated based on the dynamic characteristics during non-machining.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-208812

[0004] The inventors of the present application have previously proposed a technique for more accurately inferring the machining result by using the contact dynamic rigidity represented by the spring constant K and the attenuation coefficient C instead of the contact static rigidity represented by the spring constant K in the structure disclosed in Patent Document 1. Moreover, when the inventors of the present application infer the machining result using the contact dynamic rigidity, they have found that the dynamic characteristics of the workpiece at the machining point change compared with those during non-machining, that is, the workpiece quality in the analysis changes according to the machining state, and have obtained the concept of a workpiece quality determination device for accurately determining the workpiece quality in the analysis. Summary of the Invention

[0005] The present invention provides a workpiece quality determination device that can accurately determine the workpiece quality in the analysis.

[0006] One embodiment of the present invention is a workpiece quality determination device that calculates the workpiece quality (M′w(Z′)) in the analysis for analyzing the dynamic characteristics during machining in a machining device (2) that machines a workpiece (W) with a tool (T), and includes:

[0007] a first correspondence storage unit (103b) that stores the correspondence relationship, that is, the quality correspondence relationship, between the machining state index (Z′) that changes according to the machining state of the tool on the workpiece and the workpiece quality (M′w(Z′)) in the analysis;

[0008] A machining state index acquisition unit (125) that acquires the machining state index (Z'); and

[0009] A workpiece quality determination unit (122) that determines the workpiece quality (Mw(Z')) in the analysis based on the acquired machining state index (Z') and the quality correspondence.

[0010] According to the above embodiment, the workpiece quality in the analysis is determined based on the stored correspondence between the machining state index and the workpiece quality in the analysis, that is, the quality correspondence, and the acquired machining state index. Thus, the workpiece quality in the analysis can be determined with high precision based on the correspondence with the machining state index.

[0011] Moreover, if the workpiece quality in the analysis determined with such high precision is used, for example, together with the contact dynamic stiffness data between the workpiece and the tool exerted during machining through the contact between the workpiece and the tool, to infer the machining result of the workpiece, a high-precision inference of the machining result can be expected.

[0012] As described above, according to the above embodiment, a workpiece quality determination device capable of determining the workpiece quality in the analysis with high precision can be provided.

[0013] In addition, the reference numerals in parentheses described in the technical solution indicate the correspondence with the specific mechanisms described in the following embodiments, and do not limit the technical scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. is a diagram showing a machining system including a workpiece quality determination device and a machining inference device in Embodiment 1.

[0015] Figure 2 FIG. is a functional block diagram of the workpiece quality determination device and the machining inference device in Embodiment 1.

[0016] Figure 3 FIG. is a schematic diagram showing the interference state between the workpiece and the grinding wheel during grinding.

[0017] Figure 4 FIG. is a diagram showing the shape of the workpiece in the grinding simulation by a set of radial line segments, and is a diagram showing the interference state between the workpiece represented by the radial line segments and the outer peripheral line of the grinding wheel during grinding.

[0018] Figure 5 FIG. is a schematic diagram showing the contact dynamic stiffness, workpiece support dynamic stiffness, and tool support dynamic stiffness during grinding.

[0019] Figure 6It is a diagram of (a) the first example and (b) the second example showing the correspondence between the machining state index and the contact dynamic rigidity data in Embodiment 1.

[0020] Figure 7 It is a diagram of (a) the third example and (b) the fourth example showing the correspondence between the machining state index and the contact dynamic rigidity data in Embodiment 1.

[0021] Figure 8 It is a flowchart showing the acquisition process of the contact dynamic rigidity data used for creating the contact dynamic rigidity correspondence.

[0022] Figure 9 It is a top view of the grinding machine when obtaining the contact dynamic rigidity used for creating the contact dynamic rigidity correspondence.

[0023] Figure 10 It is a diagram showing the state of the grinding machine for a part of the process of obtaining the contact dynamic rigidity used for creating the contact dynamic rigidity correspondence.

[0024] Figure 11 It is a diagram showing an example of the correspondence between the machining state index and the workpiece quality in analysis in Embodiment 1.

[0025] Figure 12 It is a flowchart showing the acquisition process of the workpiece quality in analysis used for creating the quality correspondence.

[0026] Figure 13 It is a diagram showing a machining system including a workpiece quality determination device and a machining inference device in the deformation mode.

[0027] Figure 14 It is a schematic diagram showing the interference state of the workpiece, grinding wheel, and support device during grinding in the deformation mode. Detailed Embodiment

[0028] (Embodiment 1)

[0029] 1. Structure of the machining system 1

[0030] Refer to Figure 1 The workpiece quality determination device 131, machining inference device 3b, and machining system 1 in this Embodiment 1 will be described. The machining system 1 targets the machining device that performs grinding. The machining system 1 includes a grinding machine 2 as the machining device and a processing unit 3.

[0031] The grinding machine 2 grinds the outer peripheral surface or the inner peripheral surface of the workpiece W by rotating the workpiece W, rotating the grinding wheel T as a rotating body, i.e., a tool, and relatively approaching the grinding wheel T with respect to the workpiece W in a direction intersecting the axis of the workpiece W. The grinding machine 2 can be applied to a table traverse type grinding machine, a grinding head traverse type grinding machine, etc. In addition, the grinding machine 2 can be applied to a cylindrical grinding machine, a cam grinding machine, etc.

[0032] In the present embodiment, as Figure 1 shown, the case where the workpiece W has a shaft portion Wa as a non-processing portion and a plurality of processing portions Wb whose outer peripheral surfaces are to be ground is taken as an example. The processing portion Wb has, for example, a cylindrical outer peripheral surface coaxial with the shaft portion Wa. However, Figure 1 the workpiece W shown is an example, and the grinding machine 2 can take workpieces having various shapes as objects of grinding.

[0033] The processing unit 3 includes a control device 3a that controls the grinding machine 2 and a processing inference device 3b that infers the processing result. The control device 3a can control the grinding process by controlling the grinding machine 2. The processing inference device 3b performs processing to infer the processing result of the workpiece W by inputting information for the grinding process and performing simulation.

[0034] The processing inference device 3b can function as a simulation device independent of the grinding machine 2, and can also function as a simulation device that operates in conjunction with the grinding machine 2. In the former case, for example, the optimal grinding conditions can be determined without actually grinding the workpiece W. In the latter case, the processing inference device 3b processes in parallel with the grinding of the workpiece W by the grinding machine 2, and can, for example, correct the grinding conditions or operate in a manner that affects various controls. In addition, the processing inference device 3b can also be set as an embedded system of the grinding machine 2 and the control device 3a.

[0035] 2. Structure of the grinding machine 2 and the control device 3a

[0036] Refer to Figure 1 An example of the structure of the grinding machine 2 and the control device 3a will be described in detail. The grinding machine 2 is taken as an example of a table traverse type cylindrical grinding machine. That is, this grinding machine 2 has a structure in which the workpiece W is moved in the axial direction of the workpiece W, and the grinding wheel T is moved in a direction intersecting the axis of the workpiece W. In addition, in the present embodiment, the case where the cylindrical outer peripheral surface of the workpiece W is ground by the grinding wheel T is taken as an example.

[0037] The grinding machine 2 includes a bed 10, a table 20, a spindle device 30, a tailstock device 40, a grinding head 50, a sizing device 60, and a control device 3a. The bed 10 is provided on the installation surface. The bed 10 has the front side in the X-axis direction ( Figure 1The width (Z-axis direction length) of the lower side) is formed to be longer, and the width of the back side in the X-axis direction ( Figure 1 The upper side) is formed to be shorter.

[0038] The upper surface of the front side of the bed body 10 in the X-axis direction is provided with a Z-axis guide surface 11 extending in the Z-axis direction. And a Z-axis drive mechanism 12 is provided on the bed body 10 to drive along the Z-axis guide surface 11. In the present embodiment, the Z-axis drive mechanism 12 is exemplified by a case where it includes a ball screw mechanism 12a and a Z-axis motor 12b. The ball screw mechanism 12a extends in parallel with the Z-axis guide surface 11, and the Z-axis motor 12b drives the ball screw mechanism 12a.

[0039] In order 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 to drive the Z-axis motor 12b. The Z-axis detector 12c is, for example, an angle detector such as an encoder in the present embodiment, and detects the angle of the rotation shaft of the Z-axis motor 12b. In addition, the Z-axis drive mechanism 12 may be applied with a linear motor or the like instead of the structure including the above-mentioned ball screw mechanism 12a.

[0040] In addition, the upper surface of the back side of the bed body 10 in the X-axis direction is provided with a guide surface 13 extending in a direction intersecting the Z-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. And an X-axis drive mechanism 14 is provided on the bed body 10 to drive along the X-axis guide surface 13. In the present embodiment, the X-axis drive mechanism 14 is exemplified by a case where it includes a ball screw mechanism 14a and an X-axis motor 14b. The ball screw mechanism 14a extends in parallel with the X-axis guide surface 13, and the X-axis motor 14b drives the ball screw mechanism 14a.

[0041] In order 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 to drive the X-axis motor 14b. The X-axis detector 14c is, for example, an angle detector such as an encoder in the present embodiment, and detects the angle of the rotation shaft of the X-axis motor 14b. In addition, the X-axis drive mechanism 14 may be applied with a linear motor or the like instead of the structure including the above-mentioned ball screw mechanism 14a.

[0042] The workbench 20 is formed in a long strip shape and is supported by the Z-axis guide surface 11 of the bed body 10 so as to be movable in the Z-axis direction (horizontal left and right direction). In addition, the workbench 20 is fixed to the ball screw nut of the Z-axis ball screw mechanism 12a and moves in the Z-axis direction by the rotation drive of the Z-axis motor 12b.

[0043] The spindle device 30 constitutes a workpiece support device. The spindle device 30 supports the workpiece W and rotationally drives the workpiece W. The spindle device 30 is arranged on one end side in the Z-axis direction on the worktable 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).

[0044] The spindle housing 31 is fixed on the worktable 20. The spindle 32 is supported by the spindle housing 31 via bearings so as to be rotatable. The spindle motor 33 rotationally drives the spindle 32. The spindle center 34 supports the end face of one axial end of the workpiece W. The spindle center 34 is provided to be fixed to the spindle 32 and can rotate relative to the spindle housing 31. However, when the spindle device 30 includes rotating components such as a carrier (not shown), the spindle center 34 can also be provided to be fixed to the spindle housing 31 and cannot rotate relative to the spindle housing 31. In addition, instead of the spindle center 34, the spindle device 30 can also include a chuck for gripping the workpiece W. Further, the chuck is rotationally driven by being connected to the spindle 32.

[0045] The spindle detector 35 and the spindle drive circuit are provided to drive the spindle motor 33. In the present embodiment, the spindle detector 35 is, for example, an angle detector such as an encoder, and detects the angle of the rotating shaft of the spindle motor 33. The spindle drive circuit includes an amplifier circuit and drives the spindle motor 33.

[0046] The tailstock device 40 and the spindle device 30 together constitute a workpiece support device. The tailstock device 40 is arranged on the other end side in the Z-axis direction on the worktable 20. The tailstock device 40 is provided to be movable along the Z-axis direction on the worktable 20. The tailstock device 40 includes 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 can be provided to be non-rotatable or can be provided to be rotatable. In addition, when the internal peripheral surface of the workpiece W is ground by the grinding machine 2, the tailstock device 40 is not required.

[0047] In addition, the tailstock center 41 can be positioned at a fixed position relative to the workpiece W, or can be provided to be movable along the axial direction of the workpiece W relative to the workpiece W. In the latter case, the tailstock center 41 can also be configured to be able to adjust the pressing force in the axial direction of the workpiece W relative to the workpiece W. The pressing force can be controlled by a mechanism for adjusting the spring force, a mechanism for adjusting the fluid pressure, etc.

[0048] The grinding head 50 includes a grinding wheel T as a tool and rotationally drives the grinding wheel T. In addition to the grinding wheel T, the grinding head 50 further includes a grinding head main body 51, a grinding wheel shaft 52, a grinding wheel motor 53, and a grinding wheel drive circuit (not shown).

[0049] The grinding wheel T is formed in a disc shape. The grinding wheel T is used for grinding the outer peripheral surface or the inner peripheral surface of the workpiece W. The grinding wheel T is constituted by fixing a plurality of abrasive grains with a binder. The abrasive grains can be general abrasive grains formed of ceramic materials such as alumina and silicon carbide, super abrasive grains such as diamond and CBN, etc.

[0050] Binders include glass (V), resin (B), rubber (R), silicate (S), shellac (E), metal (M), electrophoresis (P), magnesite cement (Mg), etc. Also, 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 structure that can elastically deform or a structure that hardly elastically deforms. In the grinding wheel T that can elastically deform, the elastic modulus varies depending on the type of binder, the presence or absence of pores, the porosity, etc.

[0051] The grinding head main body 51 is formed in a rectangular shape in a plan view, for example, and is supported by the X-axis guide surface 13 of the bed 10 so as to be movable in the X-axis direction (horizontal front-rear direction). In addition, the grinding head main 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 head main body 51 constitutes a tool support device for supporting the grinding wheel T.

[0052] The grinding wheel shaft 52 is supported by the grinding head main body 51 via bearings so as to be rotatable. The grinding wheel T is fixed to the front end of the grinding wheel shaft 52 and rotates by the rotation of the grinding wheel shaft 52. The grinding wheel motor 53 rotationally drives the grinding wheel shaft 52. Static pressure bearings, rolling bearings, etc. are used as the bearings.

[0053] The grinding wheel motor 53 transmits the rotational driving force to the grinding wheel shaft 52 via a belt, for example. However, the grinding wheel motor 53 may also be arranged coaxially with the grinding wheel shaft 52. Generally, the rotational speed of the grinding wheel T generated by the drive of the grinding wheel motor 53 is high compared to the rotational speed of the workpiece W generated by the drive of 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.

[0054] 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 includes, for example, a pair of contacts that can contact the outer peripheral surface of the workpiece W and measures the outer diameter dimension of the contact portion that contacts the workpiece W.

[0055] The control device 3a is a CNC (Computer Numerical Control) device and a PLC (Programmable Logic Controller) device that performs processing control. That is, the control device 3a drives the Z-axis drive mechanism 12 and the X-axis drive mechanism 14 as the moving device based on the grinding process program and the measurement results of the sizing device 60 to control the position of the worktable 20 and the grinding head 50. That is, the control device 3a makes the workpiece W and the grinding wheel T relatively close to and separated by performing position control of the worktable 20 and the grinding head 50. In addition, the control device 3a controls the spindle device 30 and the grinding head 50. That is, the control device 3a controls the rotation of the spindle 32 and the rotation of the grinding wheel T.

[0056] 3. Structure of the processing estimation device 3b

[0057] Reference Figure 2 The structure of the processing estimation device 3b is described. The processing estimation device 3b includes: an instruction value acquisition unit 101, an estimation unit 102, a contact dynamic rigidity table storage unit (a second correspondence storage unit) 103a, a workpiece quality table storage unit (a first correspondence storage unit) 103b, a workpiece support dynamic rigidity table storage unit 103c, a tool support dynamic rigidity table storage unit 103d, a processing condition acquisition unit 106, a dynamic characteristic determination unit 107, a correction amount calculation unit 108, an output unit 109, and a processing condition optimization unit 110.

[0058] The command value acquisition unit 101 acquires the command value for controlling the grinding machine 2 during the grinding process. When the processing estimation device 3b is a simulation device independent of the grinding machine 2, the command value acquisition unit 101 receives the grinding process program and the configuration information of the grinding machine 2, and generates the command value for controlling each part of the grinding machine 2 through calculation. In addition, when the processing estimation device 3b functions as a simulation device that operates in conjunction with the grinding process of the grinding machine 2, the command value acquisition unit 101 can directly acquire the command value from the control device 3a of the grinding machine 2.

[0059] The estimation unit 102 performs grinding simulation using the command value 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 .

[0060] The state of the workpiece W includes, for example, the vibration state, temperature state, etc. of the workpiece W. The state of the grinding wheel T includes, for example, the vibration state, temperature state, grinding resistance generated at each part of the outer peripheral surface of the grinding wheel T, sharpness of the grinding wheel T, state of the abrasive grains constituting the grinding wheel T, etc. The state of the abrasive grains includes, for example, the average protrusion amount of the abrasive grains, abrasive grain distribution, etc. The shape of the workpiece W includes the shape in the middle stage of the grinding process and the shape in the end stage of the grinding process. The shape of the grinding wheel T includes the shape in the middle stage of the grinding process and the shape in the end stage of the grinding process. The mechanical state of the grinding machine 2 includes the vibration state, temperature state, etc. of the parts constituting the grinding machine 2.

[0061] In the present embodiment, an example is given in which the inference unit 102 performs processing for sequentially changing the shape of the workpiece W by using a grinding process simulation, and the shape of the workpiece W, the state of the workpiece W, and the mechanical state of the grinding machine 2 are taken as inference objects. In the present embodiment, the grinding wheel T is set as a non-deformable component to perform the grinding process simulation. In addition, the inference unit 102 can infer the grinding resistance generated at each part of the outer peripheral surface of the grinding wheel T in addition to the above inference objects.

[0062] The inference 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.

[0063] The interference amount calculation unit 111 calculates the interference amount between the workpiece W and the grinding wheel T based on the relative position of the workpiece W and the grinding wheel T obtained by the instruction value acquisition unit 101 using the instruction value, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T. The interference amount corresponds to the grinding amount in the radial direction of 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, and specifically, the removal amount in the radial direction of each part in the circumferential direction of the workpiece W. As Figure 3 shown, the interference amount is the volume of the part where the workpiece W and the grinding wheel T interfere ( Figure 3 the shaded part: interference region).

[0064] The interference amount calculation unit 111 geometrically calculates this 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 Figure 4 shown in the right part of, the outer peripheral surface shape of the workpiece W is represented by a plurality of radial line segment groups in polar coordinates with the rotation center Ow of the workpiece W as the origin. That is, the interference amount calculation unit 111 stores, as the outer peripheral surface shape of the workpiece W, a plurality of line segment groups connecting the division points ( Figure 4 the white points) on the outer peripheral surface that divide the workpiece W into equal angles (α) and the rotation center Ow (origin) of the workpiece W. By Figure 4The division points represented by the white dots in

[0065] are stored as the outer peripheral surface shape of the workpiece W before being removed by the grinding wheel T. The interference amount calculation unit 111 determines the intersection points of each line segment of the workpiece W and the line representing the outer peripheral surface shape of the grinding wheel T based on 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 ( Figure 4 the black dots). The interference amount calculation unit 111 stores the determined intersection points ( Figure 4 the black dots) as the outer peripheral surface shape of the workpiece W after removing the workpiece W by the grinding wheel T. That is, the interference amount calculation unit 111 changes the stored outer peripheral surface shape of the workpiece W.

[0066] Moreover, the interference amount calculation unit 111 subtracts the area of the triangle △Ow - b1 - b2 formed by the removed points b1, b2 (the intersection points with the grinding wheel T) and the origin Ow from the area of the triangle △Ow - a1 - a2 formed by the adjacent points a1, a2 among the points defining the outer peripheral surface shape of the workpiece W before removal and the origin Ow. The subtracted area is calculated for all adjacent points defining the outer peripheral surface shape of the workpiece W.

[0067] Moreover, the interference amount calculation unit 111 accumulates each subtracted area, multiplies the accumulated total area by the thickness of the workpiece W to calculate the interference amount (removal amount). In addition, in the above, the areas of the two types of triangles are calculated, and the difference in their areas is calculated to calculate the area of the removed part. In addition, the area of the removed part can also be calculated by directly calculating the quadrilateral a1 - a2 - b1 - b2.

[0068] As Figure 2 shown, the grinding efficiency calculation unit 112 calculates the grinding efficiency (processing 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.

[0069] The grinding characteristic determination unit 113 determines the grinding characteristic kc based on the material of the workpiece W, the type of abrasive grains and binder of the grinding wheel T, and the state of the outer peripheral surface of the grinding wheel T, etc. The state of the outer peripheral surface of the grinding wheel T is expressed, for example, by the wear state of the abrasive grains of the grinding wheel T and an index indicating sharpness. Here, the grinding characteristic determination unit 113 stores the grinding characteristics of each state through preliminary experiments, analysis, etc.

[0070] 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').

[0071] In addition, the grinding characteristic kc has a substantially linear relationship such that the higher the grinding efficiency Z′, the greater the grinding resistance Fn in the normal direction (X-axis direction). Moreover, the grinding characteristic kc changes 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 in a manner that becomes larger relative to the grinding efficiency Z′.

[0072] The contact dynamic rigidity table storage unit 103a stores the contact dynamic rigidity data (Ci(Z′), Ki(Z′)) between the workpiece W and the grinding wheel T. In particular, the contact dynamic rigidity table storage unit 103a constitutes a second correspondence storage unit 103a that stores the correspondence between the machining state index and the contact dynamic rigidity data (Ci(Z′), Ki(Z′)) described later. The workpiece support dynamic rigidity table storage unit 103c stores the workpiece support dynamic rigidity data (Cw, Kw) of the spindle device 30 and the tailstock device 40 as the workpiece support device. In particular, the workpiece support dynamic rigidity table storage unit 103c stores the correspondence between the machining conditions and the workpiece support dynamic rigidity data (Cw, Kw). The tool support dynamic rigidity table storage unit 103d stores the tool support dynamic rigidity data (Ct, Kt) of the grinding head body 51 as the grinding wheel support device. In particular, the tool support dynamic rigidity table storage unit 103d stores the correspondence between the machining conditions and the tool support dynamic rigidity data (Ct, Kt).

[0073] 4. Acquisition of processing conditions

[0074] like Figure 2 As shown in FIG. 1 , the machining condition acquisition unit 106 acquires the machining conditions when the grinding machine 2 performs the grinding process. Specifically, the machining condition acquisition unit 106 acquires the machining conditions when the inference unit 102 performs the inference (when the object is processed). The machining conditions acquired by the machining condition acquisition unit 106 are information used by the dynamic characteristic determination unit 107 to calculate each dynamic rigidity. The acquired machining conditions are, for example, the type of the workpiece W, the type of the workpiece support member, the type of the grinding wheel T, the pressing force of the spindle center 34 and the tailstock center 41, and the like.

[0075] When the processing estimation device 3b is a simulation device independent of the grinding machine 2, the processing condition acquisition unit 106 acquires the conditions for determining the dynamic rigidity by inputting the mechanical structure and grinding process program of the grinding machine 2. In addition, when the processing estimation device 3b functions as a simulation device that operates in conjunction with the grinding process of the grinding machine 2, the processing condition acquisition unit 106 may acquire the conditions for determining the dynamic rigidity by inputting the mechanical structure and grinding process program of the grinding machine 2 from the control device 3a, or may directly acquire information related to the conditions from the control device 3a of the grinding machine 2.

[0076] 5. Configuration of the Dynamic Characteristics Determining Unit 107

[0077] The dynamic characteristic determination unit 107 determines the dynamic rigidity data that affects the grinding process and the workpiece quality (M'w(Z')) in analysis. The dynamic characteristic determination unit 107 determines respectively Figure 5 the contact dynamic rigidity data (Ci(Z'), Ki(Z')), the workpiece support dynamic rigidity data (Cw, Kw), the tool support dynamic rigidity data (Ct, Kt), and the workpiece quality (M'w(Z')) in analysis shown in the figure. That is, the dynamic characteristic determination unit 107 includes a contact dynamic characteristic determination unit 121, a workpiece quality determination unit 122, a workpiece support dynamic rigidity determination unit 123, and a tool support dynamic rigidity determination unit 124.

[0078] Refer to Figure 5 The contact dynamic rigidity (Ci(Z'), Ki(Z')), the workpiece support dynamic rigidity (Cw, Kw), the tool support dynamic rigidity (Ct, Kt), and the workpiece quality (Mw) are described. The contact dynamic rigidity (Ci(Z'), Ki(Z')) is the dynamic rigidity between the workpiece W and the grinding wheel T. The workpiece support dynamic rigidity (Cw, Kw) is the dynamic rigidity on the workpiece W side related to the worktable 20, the spindle unit 30, and the device 40 including the workpiece W. In addition, the tool support dynamic rigidity (Ct, Kt) is the dynamic rigidity related to the grinding head 50 including the grinding wheel T. The workpiece quality (Mw) is the mass of the workpiece W. Hereinafter, they are described in detail.

[0079] 5-1. Contact Dynamic Rigidity, Machining State Index

[0080] The contact dynamic rigidity is the dynamic rigidity between the workpiece W and the grinding wheel T, and is the dynamic rigidity exerted through the contact between the workpiece W and the grinding wheel T during the grinding process. The contact dynamic rigidity is defined by the attenuation coefficient Ci and the spring constant Ki. In addition, the contact static rigidity different from the contact dynamic rigidity is only represented by the spring constant K and does not include the attenuation coefficient C. The attenuation coefficient Ci in the contact dynamic rigidity is a value representing the relationship between the relative speed of the workpiece W and the grinding wheel T and the external force applied to the workpiece W or the grinding wheel T. The spring constant Ki is a value representing the relationship between the relative position of the workpiece W and the grinding wheel T and the external force applied to the workpiece W or the grinding wheel T.

[0081] Moreover, in the machining device 2, the contact dynamic rigidity corresponds to the machining state index that changes according to the machining state of the workpiece W by the tool (grinding wheel T) during the grinding process. Examples of the machining state index include machining efficiency (grinding efficiency Z'), contact arc length L, g / a (abrasive grain penetration depth / abrasive grain cutting edge interval), etc. The correspondence relationship between the machining state index and the contact dynamic rigidity data (Ci(Z'), Ki(Z')), that is, the contact dynamic rigidity correspondence relationship, can be obtained through actual measurement. In addition, as Figure 3As shown, the contact arc length L is the arc length of the outer peripheral surface of the grinding wheel T in contact with the workpiece W in the cross-section orthogonal to the axis of the grinding wheel T during grinding. The contact arc length L varies according to the feed speed 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.

[0082] In Figure 6 (a) and (b), Figure 7 (a) and (b) show an example of the correspondence relationship between the machining state index and the contact dynamic rigidity data (Ci(Z′), Ki(Z′)), that is, the contact dynamic rigidity correspondence relationship. In Figure 6 (a) and (b) shown in the example, the grinding efficiency Z′ is used as the machining state index, and the attenuation coefficient Ci and the spring constant Ki in the contact dynamic rigidity do not have a linear relationship (proportional relationship) with respect to the grinding efficiency Z′ but have a non-linear relationship. More specifically, the contact dynamic rigidity correspondence relationship between the machining state index and the contact dynamic rigidity data (Ci(Z′), Ki(Z′)) is the relationship in which the pair of contact dynamic rigidity data (Ci(Z′), Ki(Z′)) varies with the degree of change of the machining state index. For example, in the quadratic plane with the horizontal axis set as the machining state index and the vertical axis set as the contact dynamic rigidity data (Ci or Ki), a function that can be specified as an approximate formula representing a curve with continuously changing slope can be used. This approximate formula can be set as a high-order function. For example, Figure 6 (a) and (b) shown in the curve is a curve defined by a cubic function.

[0083] In Figure 7 (a) and (b) shown in the example, the contact arc length L is used as the machining state index. In this case, although it shows a trend generally the same as when the machining state index is set to the grinding efficiency Z′, compared with the case where the machining state index is set to the grinding efficiency Z′, there is a trend that it is not easy to fit the curve represented by the cubic function. On the other hand, as Figure 6 (a) and (b) shown, when the machining state index is set to the grinding efficiency, it is easy to fit the curve represented by the cubic function, and it becomes easy to create an approximate formula. Therefore, it is preferable to use the grinding efficiency Z′ as the machining state index. In addition, even when the machining state index is set to g / a, the correspondence relationship between the machining state index and the contact dynamic rigidity data (Ci(Z′), Ki(Z′)) also shows a trend generally the same as that of Figure 6 (a) and (b) shown in the grinding efficiency Z′. In addition, the contact dynamic rigidity correspondence relationship can also be, instead of the above curve, the case where a plurality of straight lines are connected in the above quadratic plane. In addition, the above contact dynamic rigidity correspondence relationship can also be, instead of the case where it is specified as a function such as an approximate formula, in the form of a data table composed of the correspondence relationship of a plurality of data.

[0084] The machining state index is obtained by the machining state index acquisition unit 125 provided in the contact dynamic rigidity determination unit 121. The correspondence relationship between the machining state index and the contact dynamic rigidity data (Ci(Z′), Ki(Z′)), that is, the contact dynamic rigidity correspondence relationship, is stored in the second correspondence relationship storage unit 103a. Moreover, the contact dynamic rigidity data (Ci(Z′), Ki(Z′)) is determined by the contact dynamic rigidity determination unit 121 based on the machining state index obtained by the machining state index acquisition unit 125. That is, the contact dynamic rigidity determination device 130 is constituted by the machining state index acquisition unit 125, the second correspondence relationship storage unit 103a, and the contact dynamic rigidity determination unit 121.

[0085] 5-2. Contact Dynamic Rigidity Acquisition Process for Making Contact Dynamic Rigidity Correspondence Relationship

[0086] Refer to Figures 8 - 10 The acquisition process of the contact dynamic rigidity for making the above contact dynamic rigidity correspondence relationship will be described. As Figure 8 shown, in the contact dynamic rigidity acquisition process, first, the measurement jig 4 is installed on the grinding machine 2 and the workpiece W (S1). The measurement jig 4 is a non-contact vibrator, which is a device for applying a vibration force to the workpiece W. As Figure 9 shown, the measurement jig 4 is provided on the upper surface of the worktable 20. The measurement jig 4 can adjust the fixed position in the Z-axis direction on the upper surface of the worktable 20.

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

[0088] Here, refer to Figure 10 (a) to Figure 10 (c) to describe the structure of the measurement jig 4. The measurement 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 on the upper surface of the worktable 20 of the grinding machine 2. And, the housing 131 is formed with a hole 131a penetrating in the Z-axis direction.

[0089] The electromagnet 132 is embedded in the housing 131. The rotor 133 is installed on the outer peripheral surface of the workpiece W and is provided integrally with the workpiece W. The rotor 133 is formed 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 peripheral surface of the rotor 133 is disposed with a predetermined gap with respect to the inner peripheral surface of the housing 131. This gap becomes the distance by which the rotor 133 can move relative to the housing 131. The inner peripheral surface of the rotor 133 is formed according to the shape of the outer peripheral surface of the workpiece W. The lock nut 134 is a component for fixing the rotor 133 to the workpiece W. The fixing method of the rotor 133 is not limited to the mechanism using the lock nut 134, and various mechanisms can be adopted.

[0090] The displacement sensor 135 is disposed at a position close to the inner peripheral surface of the housing 131 and measures the distance to the outer peripheral surface of the rotor 133. That is, when the rotor 133 is vibrated by the electromagnet 132, the displacement sensor 135 measures the displacement of the rotor 133 in the direction of approaching and separating from the inner peripheral surface of the housing 131 with respect to the rotor 133 (hereinafter referred to as the radial displacement).

[0091] As Figure 10 (c) shows, the control device 136 supplies a drive current to the electromagnet 132 in order to apply a vibration force to the electromagnet 132. In addition, the control device 136 obtains the displacement measured by the displacement sensor 135, that is, the radial displacement of the rotor 133.

[0092] Therefore, in Figure 8 S1, as Figure 10 (a) shows, the shaft portion Wa, which is a non-machined portion of the workpiece W, is inserted into the rotor 133 of the measuring jig 4. Then, as Figure 10 (b) shows, the rotor 133 is fixed to the workpiece W by the lock nut 134.

[0093] Moreover, the housing 131 of the measuring jig 4 is mounted on the workbench 20. Further, it is set in a state where the workpiece W on which the rotor 133 is mounted is supported by the spindle device 30 and the tailstock device 40. At this time, as Figure 10 (b) shows, 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.

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

[0095] Next, a vibration force is applied by the measuring jig 4 (S3). The application of the vibration force by the measuring jig 4 is carried out while grinding the workpiece W with the grinding wheel T. The applied vibration force can be pulse vibration or sweep vibration in which the vibration frequency continuously changes. The application of the vibration force is carried out by supplying current from the control device 136 of the measuring jig 4 to the electromagnet 132. Moreover, the vibration force is controlled by the current supplied to the magnet 132 by the control device 136.

[0096] Next, when applying the vibration force while performing 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 is the same as the radial displacement of the portion of the workpiece W fixed to the rotor 133. Therefore, the displacement sensor 135 of the measuring jig 4 measures the radial displacement generated in the workpiece W when the vibration force is applied to the workpiece W.

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

[0098] Next, the total dynamic stiffness data (Ccom, Kcom) during grinding is calculated (S6). The total dynamic stiffness data (Ccom, Kcom) is the total (composite) dynamic stiffness data represented by the above contact dynamic stiffness data (Ci(Z′), Ki(Z′)), workpiece support dynamic stiffness data (Cw, Kw), and tool support dynamic stiffness data (Ct, Kt). The total dynamic stiffness data (Ccom, Kcom) is expressed as the sum of the above contact dynamic stiffness data (Ci(Z′), Ki(Z′)), workpiece support dynamic stiffness data (Cw, Kw), and tool 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 while applying the vibration force to the workpiece W during grinding. Therefore, the measured displacement is in a state affected by the contact dynamic stiffness data (Ci(Z′), Ki(Z′)), workpiece support dynamic stiffness data (Cw, Kw), and tool support dynamic stiffness data (Ct, Kt). Therefore, the calculation of the total dynamic stiffness data (Ccom, Kcom) becomes data generated from the relationship between the vibration force and the radial displacement of the workpiece W when applying the vibration force to the workpiece W during grinding.

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

[0101] Next, contact dynamic stiffness data (Ci(Z′), Ki(Z′)) is calculated (S8). The contact dynamic stiffness data (Ci(Z′), Ki(Z′)) is obtained by subtracting the workpiece support dynamic stiffness data (Cw, Kw) and the tool support dynamic stiffness data (Ct, Kt) from the total dynamic stiffness data (Ccom, Kcom).

[0102] Next, interpolation processing of the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) is performed (S9). The interpolation processing is a process of obtaining the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) under grinding conditions different from the actual measurement using the contact dynamic stiffness data (Ci, Ki) obtained through actual measurement. For example, an empirical formula defining the relationship between the contact arc length L, the attenuation coefficient Ci, and the spring constant Ki can be used. In addition, the interpolation processing can also apply empirical formulas, machine learning, theoretical calculations, etc. In this way, using the obtained contact dynamic stiffness data (Ci(Z′), Ki(Z′)), it is possible to create Figure 6 the contact dynamic stiffness correspondence relationship with the machining state index (grinding efficiency) shown in (a) and (b).

[0103] 5-3. Workpiece Support Dynamic Stiffness

[0104] The workpiece support dynamic stiffness is Figure 1 the dynamic stiffness related to the support in the spindle unit 30 and the tailstock unit 40 shown, and is the dynamic stiffness exerted when the workpiece W is supported by the spindle unit 30 and the tailstock unit 40, which are the workpiece support devices constituting the grinding machine 2. As Figure 5 shown, the workpiece support dynamic stiffness is defined by the attenuation coefficient Cw and the spring constant Kw. In addition, the attenuation coefficient Cw is a value representing the relationship between the relative speed of the workpiece W with respect to the reference position of the spindle unit 30 and the tailstock unit 40 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 spindle unit 30 and the tailstock unit 40 and the external force received by the workpiece W.

[0105] In addition, as described above, the workpiece support dynamic stiffness data (Cw, Kw) is stored in the workpiece support dynamic stiffness table storage unit 103c in a manner corresponding to the above machining conditions. For example, when the tailstock center 41 can control the pressing force in the axial direction of the workpiece W with respect to the workpiece W, the workpiece support dynamic stiffness data (Cw, Kw) is data that changes as the contact state between the tailstock center 41 and the workpiece W changes due to the change in the pressing force applied by the tailstock center 41. The workpiece support dynamic stiffness data (Cw, Kw) can be obtained, for example, by changing the pressing force of the tailstock center 41 and performing a hammer test in a state where the workpiece W is supported by the spindle center 34 and the tailstock center 41.

[0106] Further, through the workpiece support dynamic rigidity determination unit 123, based on the workpiece support dynamic rigidity table stored in the workpiece support dynamic rigidity table storage unit 103c, the workpiece support dynamic rigidity data (Cw, Kw) corresponding to the machining conditions acquired by the machining condition acquisition unit 106 is determined.

[0107] 5-4. Workpiece mass

[0108] The workpiece mass (M′w(Z′)) in the analysis is the mass of the workpiece W in the analysis and is a value related to the machining state index. Moreover, the correspondence relationship between the workpiece mass (M′w(Z′)) in the analysis and the machining state index, i.e., the mass correspondence relationship, is stored in the workpiece mass table storage unit 103b as the first correspondence relationship storage unit. The machining state index in the mass correspondence relationship can be the same as in the case of the above contact dynamic rigidity correspondence relationship.

[0109] In Figure 11 an example of the correspondence relationship between the machining state index and the workpiece mass (M′w(Z′)) in the analysis, i.e., the mass correspondence relationship, is shown. As Figure 11 shown, with respect to the grinding efficiency Z′ as the machining state index, the workpiece mass (M′w(Z′)) in the analysis has a non-linear relationship rather than a linear relationship (proportional relationship). More specifically, the correspondence relationship between the machining state index and the workpiece mass (M′w(Z′)) in the analysis, i.e., the mass correspondence relationship, becomes a relationship in which the degree of change of the workpiece mass (M′w(Z′)) in the analysis varies with respect to the machining state index. For example, in a quadratic plane with the horizontal axis set as the machining state index and the vertical axis set as the workpiece mass (M′w(Z′)) in the analysis, a function that can be defined as an approximate formula representing a curve with continuously changing slope can be defined. This approximate formula can be a high-order function. For example, Figure 11 the curve shown is a curve defined by a cubic function. In addition, instead of the above curve, the above mass correspondence relationship can also be a case where multiple straight lines are connected in the above quadratic plane. Further, instead of being defined as a function such as an approximate formula, the above mass correspondence relationship can also be in the form of a data table composed of the correspondence relationship of multiple data.

[0110] Although Figure 11 shows the case where the machining state index is set to the grinding efficiency Z′, even when the machining state index is set to the contact arc length L or g / a, the mass correspondence relationship between the machining state index and the workpiece mass (M′w(Z′)) in the analysis shows a trend substantially the same as that in the case of the grinding efficiency Z′ shown in Figure 11 . However, the same as in the case of the contact dynamic rigidity correspondence relationship, it is preferable to set the machining state index to the grinding efficiency Z′.

[0111] The processing state index is obtained by the processing state index obtaining unit 125, and the correspondence relationship between the processing state index and the workpiece quality (M′w(Z′)) in analysis, i.e., the quality correspondence relationship, is stored in the first correspondence relationship storage unit 103b. Moreover, the workpiece quality (M′w(Z′)) in analysis is determined by the workpiece quality determination unit 122 based on the processing state index obtained by the processing state index obtaining unit 125. That is, the workpiece quality determination device 131 is composed of the processing state index obtaining unit 125, the first correspondence relationship storage unit 103b, and the workpiece quality determination unit 122.

[0112] 5-5. Analytical Workpiece Quality Acquisition Process for Quality Correspondence Relationship Creation

[0113] The analytical workpiece quality (M′w(Z′)) in the quality correspondence relationship is created based on the dynamic characteristics of the workpiece (Mw, Cw, Kw) during non-processing and the contact dynamic stiffness data (Ci(Z′), Ki(Z′)). The following is an explanation of the workpiece quality acquisition process for creating this quality correspondence relationship according to Figure 12 the flowchart shown.

[0114] First, in Figure 12 step S11 shown, through the Figure 8 process shown, in each of a plurality of ways of changing the grinding efficiency Z′, the dynamic characteristics during processing of the detection position We of the displacement sensor 135 are measured using the vibration device 4. In addition, at this time, since the grinding efficiency Z′ is changed, the grinding resistance changes in relation to the grinding efficiency Z′, so the grinding resistance can be expressed as Fn(Z′).

[0115] Next, in step S12, the dynamic characteristics (Mw, Cw, Kw) of the detection position We of the displacement sensor 135 during non-processing are analyzed. This dynamic characteristic is, for example, the measured value of the hammer impact test during non-processing and is set as the initial dynamic characteristic (initial quality Mw, Cw, Kw).

[0116] Then, in step S13, the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) are identified in such a way that the dynamic characteristics during non-machining (initial mass Mw, Cw, Kw) at the detection position We of the displacement sensor 135 match the dynamic characteristics during machining of the respective grinding efficiencies Z′ at the detection position We of the displacement sensor 135. Specifically, in step S13, the initial mass Mw, Cw, and Kw are set as fixed parameters, the Ci(Z′) and Ki(Z′) are set as variable parameters, and as an analysis model for adding the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) to the dynamic characteristics during non-machining (initial mass Mw, Cw, Kw), the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) are identified in such a way that the dynamic characteristics of the analysis model (initial mass Mw, Cw, Kw, Ci(Z′), Ki(Z′)) match the dynamic characteristics during machining of the respective grinding efficiencies Z′.

[0117] Here, it is clarified that the vibration force frequency-compliance characteristics using the dynamic characteristics (Mw, Cw, Kw, Ci(Z′), Ki(Z′)) of the analysis model do not exactly match the measured values, that is, the vibration force frequency-compliance characteristics during machining of the respective grinding efficiencies Z′. Therefore, the workpiece mass Mw in the dynamic characteristics of the analysis model is set as a variable parameter, that is, the corrected workpiece mass M′w(Z′), and the identification process of the corrected workpiece mass (M′w(Z′)) for analysis of the machining point position Wb is performed in such a way that the dynamic characteristics of the analysis model match the dynamic characteristics during machining of the respective grinding efficiencies Z′.

[0118] That is, in step S14, the dynamic characteristics of the analysis model are defined by (M′w(Z′), Cw, Kw, Ci(Z′), Ki(Z′)), the Cw, Kw, Ci(Z′), and Ki(Z′) are set as fixed parameters, and the M′w(Z′) is set as a variable parameter. Moreover, the corrected workpiece mass (M′w(Z′)) for analysis of the machining point position is obtained in such a way that the dynamic characteristics of the analysis model match the dynamic characteristics during machining of the respective grinding efficiencies Z′.

[0119] Moreover, the corrected workpiece mass (M′w(Z′)) for analysis is expressed by the following equation (1) based on the equation of motion.

[0120] [Mathematical formula 1]

[0121]

[0122] As shown in equation (1), the corrected workpiece mass (M′w(Z′)) for analysis is related to the machining efficiency (grinding efficiency) Z′, and the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) are also related to the machining efficiency (grinding efficiency) Z′.

[0123] In addition, in the present embodiment, although the detection position We of the displacement sensor 135 and the machining point position Wb are set to different positions, the positions of the two may also coincide.

[0124] 5-6. Dynamic rigidity of tool support

[0125] The dynamic rigidity of the tool support is Figure 1 the dynamic rigidity related to the support in the grinding head main body 51 shown, and is the dynamic rigidity exerted when the grinding head main body 51, which is a grinding wheel support device constituting the grinding machine 2, supports the grinding wheel T. As Figure 5 shown, the dynamic rigidity of the tool support is defined by the attenuation coefficient Ct and the spring constant Kt. The attenuation coefficient Ct is a value representing the relationship between the relative speed of the grinding wheel T with respect to the reference position of the grinding head main body 51 and the external force received by the grinding wheel T. The spring constant Kt is a value representing the relationship between the relative position of the grinding wheel T with respect to the reference position of the grinding head main body 51 and the external force received by the grinding wheel T.

[0126] As described above, the dynamic rigidity data (Ct, Kt) of the tool support is stored in the tool support dynamic rigidity table storage unit 103d in a manner corresponding to the above machining conditions. The tool support dynamic rigidity table storage unit 103d stores the dynamic rigidity data (Ct, Kt) of the tool support, for example, in units of the type of the grinding wheel T. In addition, in a structure in which the grinding wheel T is supported by a hydrostatic bearing, when the pressure of the hydrostatic bearing can be controlled, and when the dynamic rigidity data (Ct, Kt) of the tool support changes according to the machining conditions, the tool support dynamic rigidity table storage unit 103d may also store the correspondence between the machining conditions and the dynamic rigidity data (Ct, Kt) of the tool support.

[0127] Moreover, through the tool support dynamic rigidity determination unit 124, the dynamic rigidity data (Cw, Kw) corresponding to the machining conditions acquired by the machining condition acquisition unit 106 is determined according to the tool support dynamic rigidity table stored in the tool support dynamic rigidity table storage unit 103d. In addition, the tool mass Ms of the tool T is represented by the following formula (2) based on the equation of motion.

[0128] [Mathematical formula 2]

[0129]

[0130] 6. Correction amount calculation unit 108

[0131] The correction amount calculation unit 108 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 the respective dynamic stiffness data determined by the dynamic characteristic determination unit 107 and the workpiece mass (M′w(Z′)) in the analysis. The correction amount related to the displacement can be obtained based on the respective dynamic stiffness data, the workpiece mass (M′w(Z′)) in the analysis, and the grinding resistance. That is, the correction amount related to the displacement can be calculated based on the grinding resistance, the contact dynamic stiffness data (Ci(Z′), Ki(Z′)), the workpiece support dynamic stiffness data (Cw, Kw), the tool support dynamic stiffness data (Ct, Kt), and the workpiece mass (M′w(Z′)) in the analysis.

[0132] The correction amount calculation unit 108 outputs the calculated correction amount to the inference unit 102. As described above, the inference unit 102 infers the inference target based on the relative position of the workpiece W and the grinding wheel T obtained 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, the relative position of the workpiece W and the grinding wheel T becomes a position different from the relative position of the command value due to the grinding resistance.

[0133] Therefore, when inferring the inference target, the inference unit 102 uses, as the relative position of the workpiece W and the grinding wheel T, in addition to the relative position obtained by the command value acquisition unit 101, the relative position obtained by adding the correction amount calculated by the correction amount calculation unit 108. That is, the inference unit 102 infers the inference target based on the relative position of the command value and the correction amount calculated using the respective dynamic stiffness data.

[0134] In particular, in the present Embodiment 1, the correction amount calculation unit 108 outputs the calculated correction amount to the interference amount calculation unit 111 of the inference 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 of the workpiece W and the grinding wheel T obtained 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, the relative position of the workpiece W and the grinding wheel T becomes a position different from the relative position of the command value due to the grinding resistance.

[0135] Therefore, the interference amount calculation unit 111 uses, as the relative position of the workpiece W and the grinding wheel T for calculating the interference amount, in addition to the relative position obtained by the command value acquisition unit 101, the relative position obtained by adding the correction amount calculated by the correction amount calculation unit 108. That is, the interference amount calculation unit 111 calculates the interference amount based on the relative position of the command value and the correction amount calculated using the respective dynamic stiffness data.

[0136] The interference amount calculation unit 111 calculates the interference amount considering the correction amount, so that 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 based on the interference amount considering the correction amount.

[0137] The output unit 109 outputs the inference target inferred by the inference unit 102. That is, the output unit 109 infers 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 machining system 1 (equivalent to the mechanical state of the grinding machine 2). The output unit 109 can also teach the inference result to a teaching device (not shown), for example.

[0138] The machining condition optimization unit 110 optimizes the machining conditions based on the inference result of the inference unit 102. Moreover, the machining condition optimization unit 110 can output the optimized machining conditions to the control device 3a of the grinding machine 2. In this case, the control device 3a can perform grinding using the optimized machining conditions. In addition, the control device 3a can also perform machining control using various dynamic stiffness data determined by the dynamic characteristic determination unit 107 and the analytical workpiece quality (M′w(Z′)) regardless of the inference result.

[0139] 7. Effects

[0140] According to the workpiece quality determination device 131 of the first embodiment, the analytical workpiece quality (M′w(Z′)) is determined based on the stored correspondence relationship between the machining state index and the analytical workpiece quality (M′w(Z′)), that is, the quality correspondence relationship, and the obtained machining state index. Thereby, the analytical workpiece quality (M′w(Z′)) can be determined with high precision based on the correspondence relationship with the machining state index.

[0141] Moreover, if the analytical workpiece quality (M′w(Z′)) determined with such high precision is used together with the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) between the workpiece W and the tool T exerted through the contact between the workpiece W and the tool T during machining to infer the machining result of the workpiece W, it is possible to expect high-precision inference of the machining result.

[0142] In addition, in the workpiece quality determination device 131 of the first embodiment, the analytical workpiece quality (M′w(Z′)) in the above quality correspondence relationship is made based on the workpiece dynamic characteristics (Mw, Cw, Kw) and the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) during non-machining. Thereby, the change of the analytical workpiece quality (M′w(Z′)) can be obtained more correctly, so that the analytical workpiece quality (M′w(Z′)) can be determined with high precision.

[0143] In addition, in the workpiece quality determination device 131 of the first embodiment, the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) is data generated from the relationship between the vibration force applied to the workpiece W and the displacement of the workpiece W when the workpiece W is machined by the tool T and a vibration force is applied to the workpiece W. Thus, the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) correctly represents the dynamic stiffness between the workpiece W and the grinding wheel T, so that the workpiece quality (M′w(Z′)) in analysis can be determined with high precision.

[0144] In addition, in the workpiece quality determination device 131 of the first embodiment, the above quality correspondence is defined as an approximate formula of a function representing a curve with a continuously changing slope in a quadratic plane with the horizontal axis being the machining state index and the vertical axis being the workpiece quality in analysis. In this way, by defining the quality correspondence with an approximate formula of a function of a curve representing a non-linear relationship, the change in the workpiece quality in analysis can be obtained more correctly, so that the workpiece quality (M′w(Z′)) in analysis can be determined with high precision.

[0145] In addition, in the workpiece quality determination device 131 of the first embodiment, the machining state index is the machining efficiency of the tool T on the workpiece W. Since the machining efficiency is closely related to the machining state of the workpiece W, by using the machining efficiency as the machining state index, the workpiece quality (M′w(Z′)) in analysis can be determined with high precision according to the machining state of the workpiece W.

[0146] In addition, in the workpiece quality determination device 131 of the first embodiment, the machining device 2 is a cylindrical grinding machine that grinds the cylindrical outer peripheral surface of the workpiece W with a grinding wheel T as the tool, and includes a workpiece support device composed of a spindle device 30 that supports one axial end of the workpiece W and drives it to rotate and a tailstock center 41 that supports the other axial end of the workpiece W. Moreover, the machining state index is the grinding efficiency Z′ of the grinding wheel T on the workpiece W. Thus, by setting the machining state index as the grinding efficiency, the workpiece quality (M′w(Z′)) in analysis easily fits a curve represented by a cubic function, making it easy to create an approximate formula, and enabling the workpiece quality (M′w(Z′)) in analysis to be determined with even higher precision.

[0147] In addition, in the workpiece quality determination device 131 of the first embodiment, the machining device 2 is a cylindrical grinding machine that grinds the cylindrical outer peripheral surface of the workpiece W with a grinding wheel T as the tool, and includes a workpiece support device composed of a spindle device 30 that supports one axial end of the workpiece W and drives it to rotate and a tailstock center 41 that supports the other axial end of the workpiece W. Moreover, the machining state index is the contact arc length L between the grinding wheel T and the workpiece W. Thus, the machining state index can be easily obtained and the calculation load can be reduced.

[0148] In addition, the machining result inference device 3b of the present Embodiment 1 includes a workpiece quality determination device 131, and infers the machining result of the workpiece W of the machining device 2. Further, it includes: a second correspondence storage unit 103a that stores the correspondence between the machining state index (Z') and the contact dynamic stiffness data (Ci(Z'), Ki(Z')), that is, the contact dynamic stiffness correspondence; a contact dynamic stiffness determination unit 121 that determines the contact dynamic stiffness data (Ci(Z'), Ki(Z')) based on the machining state index (Z') obtained by the machining state index acquisition unit 125 and the contact dynamic stiffness correspondence; and an inference unit 102 that infers the machining result of the workpiece W using the contact dynamic stiffness data (Ci(Z'), Ki(Z')) determined by the contact dynamic stiffness determination unit and the analytic workpiece quality (M'w(Z')) determined by the workpiece quality determination unit 122. Thus, by determining the analytic workpiece quality (M'w(Z')) based on the correspondence with the machining state index, the change in the analytic workpiece quality (M'w(Z')) is reflected in the inference of the machining result, so that the machining result can be inferred with higher accuracy.

[0149] In addition, in the machining result inference device 3b of the present Embodiment 1, the contact dynamic stiffness data in the contact dynamic stiffness correspondence is data generated from the relationship between the vibration force applied to the workpiece W and the displacement of the workpiece W when the workpiece W is machined by the tool T and a vibration force is applied to the workpiece W. Thus, the contact dynamic stiffness data (Ci(Z'), Ki(Z')) correctly represents the dynamic stiffness between the workpiece W and the grinding wheel T, so that the machining result can be inferred with higher accuracy.

[0150] In addition, the machining result inference device 3b of the present Embodiment 1 includes: a workpiece support dynamic stiffness determination unit 123 that determines the workpiece support dynamic stiffness data of the workpiece support devices 30, 40 that is exhibited when the workpiece W is supported by the workpiece support devices 30, 40 that constitute the machining device 2; a tool support dynamic stiffness determination unit 124 that determines the tool support dynamic stiffness data of the tool support device 51 that is exhibited when the tool T is supported by the tool support device 51 that constitutes the machining device 2; and a correction amount calculation unit 108 that calculates the correction amount of the relative position between the tool T and the workpiece W based on the contact dynamic stiffness data (Ci(Z'), Ki(Z')), the tool support dynamic stiffness data (Ct, Kt), the workpiece support dynamic stiffness data (Cw, Kw), and the analytic workpiece quality (M'w(Z')). The inference unit 102 infers the machining result of the tool T on the workpiece W based on the command value for machining the workpiece W and the correction amount. Thus, when calculating the correction amount of the relative position between the tool T and the workpiece W, the machining result inference device 3b uses the analytic workpiece quality (M'w(Z')) calculated with high accuracy, so that the machining result of the workpiece W can be inferred with high accuracy.

[0151] In addition, in the processing system 1 of the first embodiment, the processing inference device 3b further includes a processing condition optimization unit 110 that optimizes the processing conditions of the workpiece W based on the processing results inferred by the inference unit 102. The processing device 2 is configured to process the workpiece W with the tool T based on the optimized processing conditions. Thus, the workpiece W can be processed under the optimized processing conditions based on the highly accurately inferred processing results, so that the workpiece W with high precision can be stably manufactured, and the manufacturing cost can be reduced.

[0152] As described above, according to the above embodiment, it is possible to provide a workpiece quality determination device 131, a processing inference device 3b, and a processing system 1 that can accurately determine the workpiece quality in analysis.

[0153] Instead of the first embodiment, in Figure 13 the modified embodiment shown, the processing device 2 includes a support device 70. As Figure 14 shown, the support device 70 includes a first arm 71 and a second arm 72, and is configured to slidably support the lower portion W1 of the workpiece W and the side portion W2 opposite to the tool T by the two arms 71, 72. The support device 70 prevents the workpiece W from deforming away from the tool T during processing.

[0154] By supporting the workpiece W by the support device 70, the dynamic characteristics of the processing point Wa change, so the workpiece quality (M′w(Z′)) in analysis changes. The dynamic characteristic determination unit 107 can determine the dynamic characteristics in consideration of these. In this case, the same effects as those of the first embodiment can also be achieved. In addition, when the support device 70 is provided, the support of the workpiece W can be either cantilever support or double-sided support.

[0155] In the above embodiment, although the cutting process using grinding is exemplified, and a grinding machine 2 is used as the processing device for the grinding process, in addition to this, the cutting processes using a lathe and a machining center can also be similarly applied. In the case of cutting processes, cutting efficiency, cutting depth, etc. can be adopted as the processing state indices.

Claims

1. A workpiece quality determination device, which is a workpiece quality determination device (131) that calculates an analytical workpiece quality (M′w(Z′)) for analyzing dynamic characteristics during machining in a machining device (2) that machines a workpiece (W) with a tool (T). Wherein: It includes: A first correspondence storage unit (103b) that stores the correspondence relationship between a machining state index (Z′) that changes according to the machining state of the workpiece by the tool and the analytical workpiece quality (M′w(Z′)), that is, a quality correspondence relationship; A machining state index acquisition unit (125) that acquires the machining state index (Z′); and A workpiece quality determination unit (122) that determines the analytical workpiece quality (M′w(Z′)) based on the acquired machining state index (Z′) and the quality correspondence relationship.

2. The workpiece quality determination device according to claim 1, Wherein: The analytical workpiece quality (M′w(Z′)) in the quality correspondence relationship is made based on the dynamic rigidity of the workpiece (Cw, Kw) when not machining and the contact dynamic rigidity data (Ci(Z′), Ki(Z′)) between the workpiece and the tool exerted through the contact between the workpiece and the tool during machining.

3. The machining inference device according to claim 2, Wherein: The contact dynamic rigidity data is data generated through the relationship between the vibration force and the displacement of the workpiece when machining the workpiece with the tool and applying a vibration force to the workpiece.

4. The workpiece quality determination device according to any one of claims 1 to 3, Wherein: In the quadratic plane with the horizontal axis being the machining state index and the vertical axis being the analytical workpiece quality (M′w(Z′)), the quality correspondence relationship is defined as a function representing a curve with continuously changing slopes as an approximate formula.

5. The workpiece quality determination device according to any one of claims 1 to 3, Wherein: The machining state index is the machining efficiency of the tool for the workpiece.

6. The workpiece quality determination device according to any one of claims 1 to 3, Wherein: The machining device (2) is a cylindrical grinding machine that grinds the outer peripheral surface of the cylinder of the workpiece with a grinding wheel as the tool, and includes a workpiece support device 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, The machining state index is the grinding efficiency (Z′) of the grinding wheel for the workpiece.

7. The workpiece quality determination device according to any one of claims 1 to 3, Wherein: The machining device (2) is a cylindrical grinding machine that grinds the outer peripheral surface of the cylinder of the workpiece with a grinding wheel as the tool, and includes a workpiece support device 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, The machining state index is the contact arc length (L) between the grinding wheel and the workpiece.

8. A machining inference device (3b) that includes the workpiece quality determination device according to claim 1 and infers the machining result of the workpiece (W) in the machining device (2). Wherein: It includes: A second correspondence storage unit (103a) that stores the correspondence between the machining state index (Z′) and the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) between the workpiece and the tool exerted by the contact between the workpiece and the tool during machining, that is, the contact dynamic stiffness correspondence; A contact dynamic stiffness determination unit (121) that determines the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) based on the machining state index (Z′) obtained by the machining state index acquisition unit and the contact dynamic stiffness correspondence; and An inference unit (102) that uses the contact dynamic stiffness data (Ci(Z′), Ki(Z′)) determined by the contact dynamic stiffness determination unit and the analytical workpiece quality (M′w(Z′)) determined by the workpiece quality determination unit to infer the machining result of the workpiece.

9. The machining inference device according to claim 8, Wherein: The contact dynamic stiffness data in the contact dynamic stiffness correspondence is data generated from the relationship between the vibration force and the displacement of the workpiece when the workpiece is machined by the tool and a vibration force is applied to the workpiece.

10. The machining inference device according to claim 8, Wherein: It further includes: A workpiece support dynamic stiffness determination unit (123) that determines the workpiece support dynamic stiffness data of the workpiece support device when the workpiece is supported by the workpiece support device (30, 40) constituting the machining device; A tool support dynamic stiffness determination unit (124) that determines the tool support dynamic stiffness data of the tool support device when the tool is supported by the tool support device (51) constituting the machining device; and A correction amount calculation unit (108) that calculates the correction amount of the relative position between the tool and the workpiece based on the contact dynamic stiffness data, the workpiece support dynamic stiffness data, the tool support dynamic stiffness data, and the analytical workpiece quality (M′w(Z′)), The inference unit infers the machining result of the tool on the workpiece based on the command value for machining the workpiece and the correction amount.

11. A machining system (1), Wherein: It includes: A machining inference device that is the machining inference device according to any one of claims 8 to 10, and further includes a machining condition optimization unit (110) that optimizes the machining conditions of the workpiece based on the machining result inferred by the inference unit; and The machining device that machines the workpiece with the tool based on the optimized machining conditions.

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