Machining result estimation device

Abstract

A machining result estimation device (1) comprises: a machine model storage unit that stores a machine model (2) of a machine tool; an estimation-target-setting unit that sets an estimation target for a machining result pertaining to a workpiece (W); a machine behavior estimation unit that estimates the machine behavior of the machine model; a machining shape estimation unit (111) that estimates a machining shape on the basis of the estimation result from the machine behavior estimation unit; a removal volume calculation unit (201) that, on the basis of the estimation result from the machining shape estimation unit (111), calculates a removal volume that is removed from the workpiece (W) in each time series; a tangential resistance calculation unit (202) that, on the basis of the removal volume, calculates the tangential resistance of a machined part in each time series; a grinding power calculation unit (203) that, on the basis of the tangential resistance Ft, the rotational speed (V) of the tool (T), and the rotational speed (v) of the workpiece (W), calculates the grinding power (Q') in each time series; and a burn depth estimation unit (212) that, on the basis of the grinding power (Q') and a burn boundary power (Q'w), estimates the grinding burn depth generated in the machined part.

Description

[Rule 26, Amendment 18.07.2024] Processing result estimation device

[0001] The present invention relates to a processing result estimating device.

[0002] Conventionally, when evaluating the performance of a machine tool before it is prototyped, a machine model and a machining model of the machine tool are used to estimate the machining results of a workpiece. For example, Patent Document 1 discloses a configuration in which a three-dimensional model is used as the machine model of the machine tool.

[0003] Patent No. 4893723

[0004] In order to estimate the machining result with high accuracy, it is necessary to make a comprehensive judgment taking into consideration not only the machined shape of the workpiece but also the depth of grinding burn generated on the workpiece. However, the configuration disclosed in Patent Document 1 is not configured to estimate both the machined shape of the workpiece and the depth of grinding burn when estimating the machining result, and there is room for improvement in order to improve the estimation accuracy of the machining result.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a machining result estimating device that has excellent estimation accuracy of the machining result by a machine tool.

[0006] One aspect of the present invention is a machining result estimation device that estimates a machining result when a workpiece is machined by a tool provided on a machine tool, comprising: a machine model storage unit that stores a machine model that models the machine tool; an estimation target setting unit that sets an estimation target for the machining result of the workpiece; a machine behavior estimation unit that estimates machine behavior including static behavior of the machine model that is based on command values ​​based on machining conditions of the machine tool and design information of the machine tool in the machine model, and dynamic behavior of the machine model according to the estimation target; a machined shape estimation unit that estimates a machined shape of the workpiece that is the estimation target based on the estimation result of the machine behavior estimation unit; a removed volume calculation unit that calculates a removed volume removed from the workpiece by the tool in each time series based on the estimation result of the machined shape estimation unit; a tangential resistance calculation unit that calculates a tangential resistance at a machined portion of the workpiece in each time series based on the removed volume calculated by the removed volume calculation unit; and a grinding power calculation unit that calculates grinding power in each time series based on the tangential resistance calculated by the tangential resistance calculation unit, the rotational speed of the tool, and the rotational speed of the workpiece. and a burn depth estimation unit that estimates the depth of grinding burn that will occur in the workpiece based on the grinding power calculated by the grinding power calculation unit and a burn boundary power that is the maximum value of power required to rotate the tool within a range in which grinding burn will not occur in the workpiece.

[0007] According to the above aspect, the machining shape is estimated based on the estimated results of the machine behavior of the machine tool. Furthermore, the tangential resistance of the machining point is calculated based on the removed volume of the workpiece calculated from the estimated results of the machining shape, and the grinding power for each time series is calculated based on the tangential resistance, the rotational speed of the tool, and the rotational speed of the workpiece. The depth of grinding burn is then estimated based on the grinding power and the burn boundary power. This makes it possible to estimate both the machining shape and the burn depth, thereby improving the accuracy of estimating the machining result.

[0008] As described above, according to the above aspect, it is possible to provide a machining result estimating device that has excellent estimation accuracy of the machining result by a machine tool.

[0009] 1 is a conceptual diagram showing the configuration of a machining result estimating device 1 in embodiment 1. FIG. 2 is a functional block diagram showing the configuration of a machining shape simulation unit of the machining result estimating device 1 in embodiment 1. FIG. 3 is a functional block diagram showing the configuration of a grinding burn simulation unit of the machining result estimating device 1 in embodiment 1. FIG. 4 is a diagram of the vicinity of a sizing device equipped with an eddy current sensor in embodiment 1. FIG. 5 is an enlarged cross-sectional view of the periphery of a machined part in embodiment 1. (a) is an enlarged cross-sectional view of a workpiece showing coolant in a nucleate boiling state, and (b) is an enlarged cross-sectional view of a workpiece showing coolant in a film boiling state in embodiment 1. FIG. 6 is a conceptual diagram showing a first correspondence relationship in embodiment 1. FIG. 7 is a functional block diagram showing the configuration of a first correspondence relationship creating unit in embodiment 1. FIG. 8 is a diagram showing an output signal of an eddy current sensor in embodiment 1. FIG. 9 is a diagram showing the correspondence relationship between the actual cutting amount and grinding efficiency in embodiment 1. (a) is a diagram showing the output signal of an eddy current sensor, (b) is a diagram showing the actual cutting amount, and (c) is a diagram showing power consumption of a drive unit of a tool spindle in embodiment 1. 1 is a conceptual diagram illustrating the quantity of heat Jm passing through a film boiling region in embodiment 1. FIG. 2 is a conceptual diagram illustrating a second correspondence relationship in embodiment 1. FIG. 3 is a functional block diagram illustrating the configuration of a second correspondence relationship creation unit in embodiment 1. FIG. 4 is a diagram illustrating an overview of synchronous detection in an eddy current sensor in embodiment 1. (a) is a diagram illustrating the relationship between time and the output signal of an eddy current sensor serving as a first inflection point determination criterion, and (b) is a diagram illustrating, on a complex plane, the output signal of the eddy current sensor serving as the first inflection point determination criterion in embodiment 1. (a) is a diagram illustrating the relationship between time and the output signal of an eddy current sensor serving as a second inflection point determination criterion, and (b) is a diagram illustrating, on a complex plane, the output signal of the eddy current sensor serving as the inflection point determination criterion in embodiment 1. FIG. 5 is a diagram illustrating the time change in dimensional information of a workpiece and the burn depth in embodiment 1. (a) is a diagram illustrating an estimated result of the burn depth, and (b) is a diagram illustrating an estimated result of the machined shape in embodiment 1. FIG. 6 is a diagram illustrating an example of display of combination results in embodiment 1. 1 is a diagram showing a display example of combination results (a) to (f) in embodiment 1. FIG. 2 is a diagram showing a display example of remaining machining allowance in embodiment 1. FIG. 3 is a flowchart of grinding in embodiment 1. FIG. 4 is a flowchart explaining machining shape estimation processing in embodiment 1. FIG. 5 is a flowchart explaining grinding burn state evaluation processing in embodiment 1. FIG. 6 is a flowchart explaining grinding burn state evaluation processing in embodiment 1.FIG. 10 is a flowchart illustrating an estimation result combining process and a remaining allowance calculation process according to the first embodiment.

[0010] (Embodiment 1) 1. Overview of Machining Result Estimating Device 1 As shown in Fig. 1, the machining result estimating device 1 in this embodiment 1 includes a machine model 2 and a processing unit 3. The machining result estimating device 1 is configured by a calculation device and a storage device (not shown), and a program that causes the calculation device to realize each configuration described below. Each configuration will be described in detail below.

[0011] 2. Machine Model 2 As shown in FIG. 1, machine model 2 is a model of a machine tool. There are no particular limitations on the type of machine tool as long as it is capable of machining a workpiece, but in this embodiment 1, machine model 2 is a model of a table traverse type grinding machine, which is a cylindrical grinding device. Note that the grinding machine may also be a wheelhead traverse type grinding machine. Machine model 2 is stored in machine model storage unit 2a, which is a known storage device.

[0012] The machine model 2 is a model of a grinding machine that processes a workpiece W by rotating the workpiece W around its axis while moving a tool T in a direction including a component in the direction of the rotation axis of the workpiece W. The shape of the workpiece W is not limited and can be any shape, but in this embodiment, a member formed in a shaft shape is taken as an example of the workpiece W, as shown in FIG.

[0013] The machine model 2 includes a bed 10, a table 16, a spindle unit 30, a tailstock unit 40, a grinding wheel head 50, and a pump 60. The spindle unit 30 and the tailstock unit 40, which are provided on the table 16, function as workpiece support members that support the workpiece W. The wheel head 50 functions as a tool support member that supports the grinding wheel T. In other words, the machine model 2 grinds the workpiece W supported on the workpiece support member with the grinding wheel T supported on the tool support member. The machine model 2 also includes a sizing device (not shown) that acquires the outer dimensions of the workpiece W, and a coolant device that supplies coolant to the point at which the workpiece W is ground by the grinding wheel T.

[0014] As shown in Fig. 1, bed 10 is placed on a placement surface. On the upper surface of the front side in the X-axis direction, bed 10 is provided with Z-axis guide surface 11 extending in the Z-axis direction, and Z-axis drive mechanism 12 that drives along Z-axis guide surface 11. In this embodiment 1, Z-axis drive mechanism 12 is provided with ball screw mechanism 12a and Z-axis motor 12b as an example. Ball screw mechanism 12a extends parallel to Z-axis guide surface 11, and Z-axis motor 12b drives ball screw mechanism 12a.

[0015] A Z-axis drive circuit and Z-axis detector 12c (not shown) are provided to drive the Z-axis drive mechanism 12. The Z-axis drive circuit includes an amplifier circuit and drives the Z-axis motor 12b. The Z-axis detector 12c detects the angle of the rotation axis of the Z-axis motor 12b. Note that the Z-axis drive mechanism 12 may be configured with a linear motor or the like instead of the ball screw mechanism 12a.

[0016] Additionally, bed 10 is provided with an X-axis guide surface 13 extending in the X-axis direction intersecting the Z-axis direction on the upper surface on the rear side in the X-axis direction. Bed 10 is also provided with an X-axis drive mechanism 14 that drives along X-axis guide surface 13. In this embodiment, an example is given in which 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.

[0017] 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. The X-axis detector 14c detects the rotation angle of the rotation shaft of the X-axis motor 14b. Note that the X-axis drive mechanism 14 can also be configured with a linear motor or the like instead of the ball screw mechanism 14a.

[0018] The table 16 is formed in an elongated shape and is supported movably in the Z-axis direction (horizontal left-right direction) on the Z-axis guide surface 11 of the bed 10. The table 16 is also fixed to a ball screw nut of the Z-axis ball screw mechanism 12a, and moves in the Z-axis direction by the rotational drive of the Z-axis motor 12b.

[0019] The spindle unit 30 supports the workpiece W and drives it to rotate. The spindle unit 30 is disposed on one end side in the Z-axis direction on the table 16. The spindle unit 30 includes a spindle housing 31, a workpiece spindle 32, a workpiece motor 33, a spindle center 34, a spindle detector 35, and a spindle drive circuit (not shown).

[0020] The spindle housing 31 is fixed on the table 16. The workpiece spindle 32 is rotatably supported by the spindle housing 31 via a bearing. A workpiece motor 33 rotationally drives the workpiece spindle 32. The spindle center 34 constitutes a workpiece support member that supports an end face of one axial end (the left end in FIG. 1 ) of the workpiece W. Note that the spindle unit 30 may be provided with a chuck that grips the workpiece W as a workpiece support member, instead of the spindle center 34.

[0021] The spindle detector 35 and the spindle drive circuit are provided to drive the workpiece drive motor 33. The spindle detector 35 detects the rotation angle of the rotary shaft of the workpiece drive motor 33. The spindle drive circuit includes an amplifier circuit and drives the workpiece drive motor 33.

[0022] The tailstock device 40 supports the workpiece W together with the spindle device 30. The tailstock device 40 is disposed on the other end of the table 16 in the Z-axis direction. The tailstock device 40 is provided so as to be movable in the Z-axis direction on the table 16. The tailstock device 40 includes a tailstock center 41 and an adjustment mechanism 42. Note that when the machine model 2 grinds the inner peripheral surface of the workpiece W, the tailstock device 40 is not required. The tailstock center 41 constitutes a workpiece support member that supports the end face of the other axial end (the right end in FIG. 1 ) of the workpiece W. In the first embodiment, the tailstock device 40 includes an adjustment mechanism 42. The adjustment mechanism 42 is formed, for example, by a spring, and is configured so that the tailstock center 41 exerts a pressing force. When the tailstock center 41 exerts a pressing force on the workpiece W, the spindle center 34 also exerts a pressing force on the workpiece W as a reaction.

[0023] The wheel head 50 includes a grinding wheel T and rotates the grinding wheel T. In addition to the grinding wheel T, the wheel head 50 also includes a wheel head body 51, a grinding wheel spindle 52, a grinding wheel motor 53, and a grinding wheel drive circuit (not shown).

[0024] The grinding wheel T is formed in a disk shape. The grinding wheel T is used to grind the outer or inner peripheral surface of a workpiece W. The grinding 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 grinding 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 grinding head body 51 constitutes a tool support member that supports the grinding wheel T.

[0025] The grinding wheel spindle 52 is rotatably supported on 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. A hydrostatic bearing, a rolling bearing, or the like is used as the bearing. 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.

[0026] The sizing device 17 functions as a detector that measures the dimension (diameter) of the workpiece W. However, the detector is not limited to the sizing device 17, and may be a contact sensor having a single probe or a non-contact sensor such as a laser displacement meter.

[0027] 4, the sizing device 17 mainly includes a device main body 171, a pair of contactors 172a, 172b, a pair of fingers 173a, 173b, and a differential transformer 174. The contactors 172a, 172b are provided so as to be able to come into contact with the outer peripheral surface of the workpiece W. Specifically, of the pair of contactors 172a, 172b, one contactor 172a comes into contact with the outer peripheral surface of the workpiece W from above, and the other contactor 172b comes into contact with the outer peripheral surface of the workpiece W from below. The fingers 173a, 173b hold the contactors 172a, 172b and support the contactors 172a, 172b so as to be displaceable relative to the device main body 171. Specifically, one finger 173a of the pair of fingers 173a, 173b supports one contact 172a, and the other finger 173b supports the other contact 172b.

[0028] The differential transformer 174 is housed in the device main body 171. The differential transformer 174 detects the displacement of the pair of fingers 173a, 173b, which displaces in accordance with the displacement of the pair of contacts 172a, 172b, and outputs an electrical signal corresponding to the displacement of the fingers 173a, 173b to the control unit 300. The control unit 300 detects the positions of the fingers 173a, 173b when the pair of contacts 172a, 172b come into contact with the outer peripheral surface of the workpiece W based on the electrical signal output from the differential transformer 174, and can obtain the measurement result of the outer diameter of the workpiece W by the sizing device 17 based on the positions of the fingers 173a, 173b. Note that the sizing device 17 may be equipped with other detectors, such as an acceleration sensor, a microphone, or a temperature sensor.

[0029] The pump 60 supplies coolant and other fluids to the coolant device. The configuration of the pump 60 is not limited, and any known configuration can be adopted.

[0030] 3. Vibration Generating Unit 4 The grinding machine modeled by the machine model 2 has a vibration generating unit 4. The vibration generating unit 4 generates vibrations by itself when driven, and in this embodiment 1, these units correspond to the Z-axis motor 12b, the X-axis motor 14b, the workpiece motor 33, the grinding wheel motor 53, and the pump 60. All of these units have rotating parts, and generate periodic vibrations by themselves due to imbalances in the rotating parts. In addition to these, the vibration generating unit 4 can also be configured to generate vibrations generated by movement of the table 16 and the wheel head 50, and vibrations generated due to the frequency of AC current when AC current is applied to the machine tool.

[0031] 1, the processing unit 3 includes a machining shape simulation unit 100, a grinding burn simulation unit 200, a control unit 300, an estimation result combining unit 301, a combined result display unit 302, a machining condition evaluation unit 303, a remaining machining allowance calculation unit 304, and a remaining machining allowance display unit 305. Each component of the processing unit 3 will be described in detail below.

[0032] 5. Machining Shape Simulation Unit 100 As shown in FIG. 2 , the machining shape simulation unit 100 includes a workpiece shape storage unit 101, a stiffness storage unit 102, a command value storage unit 103, a machining condition storage unit 104, a vibration information storage unit 105, an estimation target setting unit 106, a vibration correspondence storage unit 107, a design information similarity evaluation unit 108, a generated vibration identification unit 109, a machine behavior estimation unit 110, and a machining shape estimation unit 111.

[0033] 5-1. Workpiece shape storage unit 101, stiffness storage unit 102 The workpiece shape storage unit 101 stores the shape of the workpiece W. The workpiece shape storage unit 101 is configured to store the shape of the workpiece W that has changed due to machining, updating the shape. The stiffness storage unit 102 stores the stiffness of each part in the machine model 2 and the stiffness of the workpiece. The stiffness is calculated by a simulation in the machine model 2.

[0034] 5-2. Command value storage unit 103, machining condition storage unit 104 The command value storage unit 103 stores command values ​​based on the machining conditions of the workpiece W in the machine model 2. The command values ​​include the X-axis value, Y-axis value, and Z-axis value of the machining point by the grinding wheel T, the rotational speed of the grinding wheel T, and the rotational speed of the workpiece W. The machining condition storage unit 104 stores the machining conditions of the workpiece W in the machine model 2. The machining conditions include the machining allowance of the machined portion of the workpiece W, the feed rate of the grinding wheel T or the workpiece W, etc. When the machining conditions stored in the machining condition storage unit 104 are changed, the command values ​​stored in the command value storage unit 103 are also changed accordingly.

[0035] 5-3. Vibration Information Storage Unit 105 The vibration information storage unit 105 stores vibration information based on vibrations generated by the vibration generating unit 4 provided in the machine model 2. The vibration information may include the frequency, amplitude, phase, period, and changes over time of the vibrations. In the first embodiment, the vibration information is stored for vibrations generated by the Z-axis motor 12b, the X-axis motor 14b, the workpiece motor 33, the grinding wheel motor 53, and the pump 60.

[0036] 5-4. Estimation target setting unit 106 The estimation target setting unit 106 sets a target to be output as a machining result by a machining shape estimation unit (described later). The estimation target can be set by the user setting any configuration or part of the workpiece W. In the first embodiment, the roundness or dimensional change of the cylindrical workpiece W is set as the estimation target.

[0037] 5-5. Vibration Correspondence Relationship Storage Unit 107 The vibration correspondence relationship storage unit 107 stores in advance the correspondence between the design information of the machine tool for creating the correspondence relationship, the machining conditions of the machine tool for creating the correspondence relationship, and the vibration generated by the vibration generating unit 4 provided on the machine tool for creating the correspondence relationship. The correspondence relationship can be created in advance based on actual measurement values ​​acquired from the machine tool for creating the correspondence relationship. The design information of the machine tool includes the shape of the machine tool, support rigidity, grinding wheel sharpness, etc. In a machine tool, the sharpness of the grinding wheel deteriorates with use, so the design information can be set so that the sharpness of the grinding wheel deteriorates over time.

[0038] 5-6. Design information similarity evaluation unit 108, generated vibration identification unit 109 The design information similarity evaluation unit 108 evaluates the similarity between the design information constituting the correspondence stored in the vibration correspondence storage unit 107 and the design information of the machine tool in the machine model 2. The generated vibration identification unit 109 identifies the vibration generated from the vibration generating unit 4 in the correspondence based on the design information evaluated to have high similarity based on the evaluation result of the design information similarity evaluation unit 108. As a result, among the vibration generating units 4 that are sources of multiple vibrations corresponding to the design information of the machine tool in the correspondence stored in the vibration correspondence storage unit 107, the vibration of the vibration generating unit 4 corresponding to the design information with high similarity is identified.

[0039] 5-7. Machine behavior estimation unit 110 The machine behavior estimation unit 110 estimates the machine behavior of the machine model 2 based on the machine model 2, command values ​​based on the machining conditions of the machine tool, and vibrations generated by the vibration generation unit 4. The machine behavior is not limited to, but may be, for example, grinding wheel vibrations in the grinding wheel T, grinding wheel dynamic characteristics, workpiece runout in the workpiece W, workpiece dynamic characteristics, etc. In the first embodiment, the vibrations identified by the generated vibration identification unit 109 are used as the vibrations generated by the vibration generation unit 4.

[0040] In the first embodiment, the machine behavior estimation unit 110 estimates machine behavior including static behavior based on command values ​​based on the machining conditions of the machine tool and design information of the machine tool in the machine model 2, and dynamic behavior according to the estimation target out of dynamic behaviors based on vibrations generated from the vibration generating unit 4. Note that, although the static behavior and dynamic behavior of the machine behavior of the machine model 2 can be distinguished conceptually, the machine behavior estimated by the machine behavior estimation unit 110 is output as a blend of both.

[0041] 5-8. Machining Shape Estimation Unit 111 The machining shape estimation unit 111 estimates the machining shape of the workpiece W by the machine tool that is a model of the machine model 2, based on the estimation result of the machine behavior estimation unit 110. In this embodiment 1, for the estimation target set by the estimation target setting unit 106, the time-series change in the shape of the workpiece W is estimated based on the estimation result of the machine behavior, and the machining shape is estimated. In this embodiment 1, the roundness of the cylindrical workpiece W is the estimation target.

[0042] 6. Grinding Burn Simulation Unit 200 Next, the grinding burn simulation unit 200 shown in Fig. 1 will be described in detail. First, the cause of grinding burn occurring in the processed portion Wa of the workpiece W when the processed portion Wa is ground by the grinding machine 2 will be described below. As shown in Fig. 5, in a configuration in which the processed portion Wa of the workpiece W is ground while supplying a coolant CL to the processed portion Wa, the explanation will be given from the perspective of changes in the state of the coolant supplied to the processed portion Wa during processing.

[0043] When the temperature of the workpiece Wa rises due to heat generated in the workpiece Wa during grinding of the workpiece W and reaches the boiling point of the coolant, the coolant CL first boils near the surface of the workpiece Wa, producing bubbles Bo, as shown in Figure 6(a). In the initial stage of boiling, each bubble Bo is generally independent, and the coolant CL in liquid form is in contact with the surface of the workpiece Wa. This state is called the nucleate boiling state of the coolant CL. In the nucleate boiling state, the cooling performance of the coolant CL for the workpiece Wa is maintained, preventing the workpiece Wa from overheating and preventing grinding burns from occurring on the workpiece Wa.

[0044] On the other hand, if the temperature of the workpiece Wa further rises and exceeds the boiling point of the coolant CL, the boiling of the coolant CL near the surface of the workpiece Wa becomes more active, generating numerous bubbles B, which cause adjacent bubbles B to fuse together. As the bubbles B fuse together, a bubble layer Bm is formed, as shown in FIG. 6( b). Because the surface of the workpiece Wa is covered by the bubble layer Bm, the liquid coolant CL no longer comes into contact with the surface of the workpiece Wa. This state is called film boiling of the coolant CL. In film boiling, the cooling performance of the coolant CL for the workpiece Wa is significantly reduced, causing the workpiece Wa to overheat, resulting in grinding burns on the workpiece Wa. Therefore, the timing at which the coolant CL transitions from nucleate boiling to film boiling is the timing at which grinding burns occur on the workpiece Wa.

[0045] As shown in Figure 5, in an example of up-cut grinding, coolant CL flows between the grinding wheel T and the workpiece Wa of the workpiece W along the rotational direction V of the grinding wheel T. Of the contact arc LC between the grinding wheel T and the workpiece Wa, indicated by the symbol Lc, the region LW indicated by the symbol Lw, which is close to the inflow position of the coolant CL, is a nucleate boiling region, while the region LM indicated by the symbol Lm, which is far from the inflow position of the coolant CL, is a film boiling region. As the workpiece W is fed in the direction of arrow v during grinding, the workpiece Wa is removed as shown by the dashed line, and the film boiling region relatively advances in the opposite direction to the feed direction of the workpiece W. Even in the case of down-cut grinding, in which the rotational direction V of the grinding wheel T is reversed, the region close to the inflow position of the coolant CL is a nucleate boiling region, and the region far from the inflow position of the coolant CL is a film boiling region.

[0046] 3, the grinding burn simulation unit 200 includes a removal volume calculation unit 201, a tangential resistance calculation unit 202, a grinding power calculation unit 203, a dimension information acquisition unit 204, a film boiling boundary power acquisition unit 205, a contact arc length acquisition unit 206, a contact arc heat flux calculation unit 207, a first correspondence relationship storage unit 208, a film boiling region length calculation unit 209, a transmitted heat quantity calculation unit 210, a feed rate acquisition unit 211, a burn depth estimation unit 212, a second correspondence relationship storage unit 213, a first correspondence relationship creation unit 220, and a second correspondence relationship creation unit 250. These units are configured as storage devices or arithmetic units. Each component will be described in detail below.

[0047] 6-1. Removed Volume Calculation Unit 201 The removed volume calculation unit 201 calculates the removed volume removed from the workpiece W by the grinding wheel T in each time series based on the estimation result of the machining shape estimation unit 111. In this embodiment, the removed volume is calculated from the machining shape estimated by the machining shape estimation unit 111 and the feed speed of the grinding wheel T.

[0048] 6-2. Tangential Resistance Calculation Unit 202 The tangential resistance calculation unit 202 calculates the tangential resistance Ft at the machined portion Wa of the workpiece W for each time series based on the removed volume calculated by the removed volume calculation unit 201. In this embodiment, the tangential resistance calculation unit 202 calculates the tangential resistance Ft based on the correspondence relationship between the removed volume and the tangential resistance stored in the third correspondence relationship storage unit 202a. In this embodiment, the correspondence relationship stored in the third correspondence relationship storage unit 202a is a calibration curve representing the correspondence relationship between the removed volume and the tangential resistance, and this calibration curve is created by calculating the tangential resistance from the tangential component force based on the amount of change in power consumption of the grinding wheel motor 53 when machining is performed at different feed rates of the grinding wheel T and the amount of feed power of the grinding wheel spindle 52.

[0049] 6-3. Grinding Power Calculation Unit 203 The grinding power calculation unit 203 constitutes a grinding energy calculation unit that acquires grinding energy Q', which is the energy required to grind the workpiece Wa by the grinding machine 2. In this embodiment, the grinding power calculation unit 203 calculates the grinding energy Q' as the product of the tangential resistance Ft calculated by the tangential resistance calculation unit 202 and the relative rotational speed V+v, which is based on the rotational speed V of the grinding wheel T and the rotational speed v of the workpiece W. Note that the grinding energy Q' is the grinding power per unit width in the axial direction of the grinding wheel spindle 52 at the workpiece Wa.

[0050] 6-4. Dimensional Information Acquisition Unit 204 The dimensional information acquisition unit 204 acquires the output of the sizing device 17 and acquires dimensional information of the workpiece W. Note that, if the actual cutting depth is obtained according to the command value, the dimensional information acquisition unit 204 may acquire the dimensional information of the workpiece W based on the command value without using the sizing device 17.

[0051] 6-5. Film boiling boundary power acquiring unit 205 The film boiling boundary power acquiring unit 205 constitutes a film boiling boundary energy acquiring unit that acquires film boiling boundary energy Q'w, which is the energy required for the coolant supplied to the workpiece Wa to reach a film boiling state when the workpiece Wa is ground by the grinding machine 2. In this embodiment, the film boiling boundary power acquiring unit 205 acquires, as the film boiling boundary energy Q'w, film boiling boundary power that corresponds to the grinding power required for the coolant supplied to the workpiece Wa to reach a film boiling state.

[0052] 6-6. Contact Arc Length Acquisition Unit 206 The contact arc length acquisition unit 206 acquires the length Lc of the contact arc LC between the grinding wheel T and the workpiece Wa in a cross section (see FIG. 4) perpendicular to the grinding wheel spindle 52 of the grinding wheel T. The contact arc LC is a partial arc along the surface of the grinding wheel T. Note that, since the length Lc of the contact arc LC between the grinding wheel T and the workpiece Wa is usually sufficiently small compared to the outer periphery of the grinding wheel T, the contact arc LC may be approximated to a straight line, and the length Lc may be the length of a line segment. The length Lc can be geometrically calculated based on the dimensional information of the workpiece W acquired by the dimensional information acquisition unit 204, the outer diameter of the grinding wheel T, and the cutting depth of the workpiece Wa.

[0053] The contact arc heat flux calculation unit 207 calculates the heat flux q per unit area in the contact arc LC between the grinding wheel T and the workpiece Wa. The heat flux q can be calculated from the following relational expression (1) based on the grinding power Q' acquired by the grinding power calculation unit 203 and the length Lc of the contact arc LC acquired by the contact arc length acquisition unit 206.

[0054]

[0055] 6-8. First Correspondence Relationship Storage Unit 208 The first correspondence relationship storage unit 208 stores a first correspondence relationship which is the correspondence relationship between the length Lw of the non-film boiling region LW, which is the region that has not yet reached the film boiling state in the contact arc LC between the grinding wheel T and the workpiece Wa, the heat flux qw per unit area generated in the non-film boiling region LW by grinding, and the film boiling boundary power Q'w. Since qw and Lw are inversely proportional to each other, the following relational expression (2) holds. The first correspondence relationship indicates the boundary line for the occurrence of grinding burn on the graph of heat flux vs. contact arc length shown in FIG. 7.

[0056]

[0057] 6-9. First Correspondence Relationship Creation Unit 220 The first correspondence relationship creation unit 220 creates the above-mentioned first correspondence relationship. In this embodiment, as shown in Fig. 8, the first correspondence relationship creation unit 220 includes a structure change detection unit (eddy current sensor 20), an output signal acquisition unit 221, a dimension information acquisition unit 204, an actual cutting depth calculation unit 222, a grinding efficiency calculation unit 223, and a grinding burn occurrence estimation unit 44, which are configured by a storage device or an arithmetic unit. Note that, in the first correspondence relationship creation unit 220, the configurations provided in the grinding burn simulation unit 200 can be used for the components that overlap with those provided in the grinding burn simulation unit 200.

[0058] 6-9-1. Eddy current sensor 20 In this embodiment, an eddy current sensor 20 is used as a microstructural change detection unit that detects microstructural changes that occur in the workpiece Wa due to grinding by the grinding machine 2. In this embodiment 1, as shown in Fig. 3, the sensor head of the eddy current sensor 20 is attached to the device body 171 of the sizing device 17 and is located on the opposite side of the grinding wheel T with respect to the workpiece W. Note that in Fig. 3, the reference numeral 20 indicates the position of the sensor head, and the sensor body is not shown.

[0059] 8, the eddy current sensor 20 has a coil serving as an oscillator 21, and applies an output signal to a probe 22 provided at the tip of the sensor head of the eddy current sensor 20, thereby applying a magnetic field to the workpiece W and inducing eddy currents inside the workpiece W. The eddy current sensor 20 then amplifies the change in impedance acquired via the probe 22 in an amplifier 23 and inputs it to a detector 24, extracts only the frequency component of the oscillator 21, processes the signal in a signal processor 25, and outputs it. The magnitude of the eddy current, and therefore the magnitude of the output signal, changes depending on the condition of the processed portion of the workpiece W, etc.

[0060] The eddy current sensor 20 is configured to supply multiple excitation currents with different frequencies to the coil. The frequency of the excitation current can be set by a frequency setting unit (not shown). Since the penetration depth of the eddy current varies depending on the frequency of the excitation current, the frequency of the excitation current can be set according to the target penetration depth of the eddy current. The target penetration depth of the eddy current is set to match the surface layer where grinding burn may occur, and can be, for example, 1 to 100 μm from the machined surface, preferably 1 to 50 μm, and more preferably 10 to 30 μm. If the penetration depth is shallow, the sensitivity of the eddy current sensor becomes too high, resulting in a lower signal-to-noise ratio and reduced detection accuracy. On the other hand, if the penetration depth is deep, the detection level of magnetic property changes decreases in areas shallow from the machined surface, resulting in reduced detection accuracy.

[0061] The frequency of the excitation current according to the penetration depth can be set in a frequency band of 20 kHz to 200 MHz, preferably 20 kHz to 100 kHz, and more preferably 250 to 2500 kHz. In this embodiment, the frequency of the excitation current is set to 250 kHz so that the penetration depth of the eddy current is 30 μm.

[0062] 6-9-2. Output Signal Acquisition Unit 221 The output signal acquisition unit 221 acquires the output signal P output from the eddy current sensor 20. The output signal P is acquired as an eddy current voltage, as shown in FIG.

[0063] Dimensional Information Acquisition Unit 204 The dimensional information acquisition unit 204 acquires dimensional information of the workpiece W. In this embodiment, as described above, the dimensional information of the workpiece W can be obtained by detecting the dimensions of the workpiece W during machining using the sizing device 17. Note that instead of using the sizing device 17, the dimensional information of the workpiece W may be indirectly calculated and acquired based on the coordinate position of the X-axis, which is the cutting axis of the workpiece W, output from the control unit 300.

[0064] 6-9-4. Actual Cut-in Amount Calculating Unit 222 The actual cut-in amount calculating unit 222 acquires the cut-in amount per rotation of the workpiece W based on the amount of change in the dimensional information of the workpiece W acquired by the dimensional information acquiring unit 204. Then, the grinding efficiency calculating unit 223 calculates the grinding efficiency Z' based on the cut-in amount per rotation acquired by the actual cut-in amount calculating unit 222. The grinding efficiency Z' can be calculated from the rotational speed of the workpiece spindle motor and the actual cut-in amount using the following formula (3):

[0065] Here, ta is the actual cutting depth, d is the diameter of the workpiece, and Nw is the spindle rotation speed.

[0066] Then, the rotational speeds (spindle rotational speeds) of the plurality of grinding spindles 52 are obtained from the grinding wheel motor 53, and calculation is performed at each spindle rotational speed. In the present embodiment 1, as shown in Fig. 10, the grinding efficiency Z' is calculated for three patterns of spindle rotational speeds R1, R2, and R3 (where the relationship R1 < R2 < R3 is satisfied).

[0067] The grinding burn occurrence estimation unit 44 detects a sudden change region Sc where the output signal P (eddy current voltage V) acquired by the output signal acquisition unit 221 suddenly changes as shown in FIG. 11( a) during a specific section Ts in which the grinding efficiency of the grinding machine 2 is continuously changed by the control unit 300, and estimates that grinding burn has occurred in the processed portion Wa. The specific section Ts is a section included in the rough grinding step S11 in the grinding process. As shown in FIG. 11( b), the specific section Ts is a transient response period during which the actual cutting depth moves from an initial value A0 (a state in which the grinding wheel T and the workpiece W are not in contact) to a command value SA instructed by the control unit 300 based on the grinding conditions. During this period, the actual cutting depth changes so as to continuously increase from the initial value A0 to the command value SA. As shown in FIG. 10, since the actual cutting depth is proportional to the grinding efficiency Z', in the specific section Ts, the grinding efficiency Z' also changes so as to increase continuously from the initial value corresponding to the initial value A0 to the target value corresponding to the command value SA.

[0068] The sudden change region Sc refers to a region in the specific section Ts where the output signal P suddenly changes from its initial value P0. For example, the sudden change region Sc can include the point where the value of the output signal P in the specific section Ts reaches a predetermined reference value Ps. In this embodiment, as shown in FIG. 11(a), the reference value Ps corresponds to half the maximum change amount Pm, which is the maximum change amount of the output signal P from its initial value P0 in the specific section Ts. When the output signal P reaches the reference value Ps, the actual cutting depth is A, as shown in FIG. 11(b), and the driving power of the grinding wheel motor 53 when the actual cutting depth is A is B, as shown in FIG. 11(c). Alternatively, the reference value Ps can be a region where the rate of change of the output signal P in the specific section Ts is greater than a predetermined reference rate of change.

[0069] In the sudden change region Sc, grinding burn occurs in the processed portion due to heat generated by grinding the processed portion of the workpiece W with the grinding wheel T. Grinding burn occurs in a short period of time, and the output signal (eddy current voltage) of the eddy current sensor 20, which changes in response to the structural change (formation of a work-affected layer) caused in the workpiece W by grinding burn, also changes within a short period of time, so the output signal exhibits a steep change (sudden change).

[0070] Then, the driving power B (see FIG. 11(c)) of the grinding wheel spindle 52 acquired by the grinding burn occurrence estimation unit 44 is converted into a value per unit width and acquired as the film boiling boundary power Q'w in the above-mentioned first correspondence relationship. Furthermore, the contact arc length acquisition unit 206 acquires the length of the contact arc in the abrupt change region Sc as Lw. Furthermore, the contact arc heat flux calculation unit 207 calculates qw from the relational expression qw = Q'w / Lw. These are then stored as the first correspondence relationship in the first correspondence relationship storage unit 208.

[0071] 6-9-5. Cooling State Grasping Unit 225 The cooling state grasping unit 225 grasps the cooling state by the coolant CL and outputs information related to the cooling state. In this embodiment, the cooling state by the coolant CL includes at least the grinding wheel sharpness K and may further include the temperature Ta, flow rate Fa, and coolant power Qa of the coolant CL. Here, the film boiling boundary power Q'w varies depending on the grinding wheel sharpness K, the temperature Ta, flow rate Fa, and coolant power Qa of the coolant CL, which are acquired by the cooling state grasping unit 225 shown in FIG. 8 . Therefore, in order to reflect the influence of these changes on the film boiling boundary power Q'w, the cooling state reflecting unit 230 performs a regression analysis using the film boiling boundary power Q'w as the objective variable and at least one or all of the grinding wheel sharpness K, the temperature Ta, flow rate Fa, and coolant power Qa of the coolant CL as explanatory variables, and updates the film boiling boundary power Q'w stored in the first correspondence relationship storage unit 208 based on the results of the regression analysis. The explanatory variables preferably include the grinding wheel sharpness K. This is because the influence on the film boiling boundary power Q'w is large.

[0072] The grinding wheel sharpness K is calculated by the grinding wheel sharpness calculation unit 226 in the cooling state grasping unit 225 based on the relational expression K = (Q / width) / Z' from the grinding power Q in the grinding wheel motor 53 and the grinding efficiency Z' calculated by the grinding efficiency calculation unit 223.

[0073] The temperature Ta of the coolant CL is acquired by a coolant temperature acquisition unit 228 in the cooling state grasping unit 225. The flow rate Fa of the coolant CL is acquired by a coolant flow rate acquisition unit 229 in the cooling state grasping unit 225. Furthermore, the coolant power Qa is calculated by a coolant power calculation unit 227 as the difference between the spindle power Q0 when the tool (grinding wheel T) is idling without supplying the coolant CL in the grinding machine 2, and the spindle power Q1 when the coolant CL is supplied.

[0074] In this embodiment, the film boiling boundary power Q′w can be expressed as the following relational expression (4) using a multiple regression equation for the regression analysis. ０ ~b ４ are all coefficients. The regression analysis method is not limited to this, and known statistical methods or machine learning can also be applied.

[0075]

[0076] Then, the film boiling boundary power acquiring unit 205 acquires the film boiling boundary power Q'w from the heat flux q acquired by the contact arc heat flux calculating unit 207 and the length Lc of the contact arc LC acquired by the contact arc length acquiring unit 206, based on the first correspondence relationship (Q'w = q × Lw) that reflects the influence of each explanatory variable acquired by the cooling state grasping unit 225. That is, in the graph shown in Fig. 7, by specifying the coordinates (Lc, q), the film boiling boundary power Q'w on the curve that indicates the first correspondence relationship is acquired.

[0077] The film boiling region length calculation unit 209 calculates the length Lm of the film boiling region LM in the contact arc Lc based on the grinding power Q', the film boiling boundary power Q'w, and the length Lc of the contact arc LC. Lm can be calculated based on the following relational expressions (5) and (6).

[0078]

[0079]

[0080] Here, if the length Lm of the film boiling region LM is 0 or less, it can be determined that the film boiling region LM has not occurred and that grinding burn has not occurred, and if the length Lm of the film boiling region LM is greater than 0, it can be determined that grinding burn has occurred.

[0081] 6-11. Passed Heat Quantity Calculation Unit 210 The passed heat quantity calculation unit 210 calculates the film boiling region passed heat quantity Jm, which is the amount of heat generated in the film boiling region LM, which is the region where the coolant CL is in a film boiling state in the machined portion Wa, based on the grinding power Q' and the film boiling boundary power Q'w. In this embodiment, the film boiling region passed heat quantity Jm is calculated using the following relational expression (7) based on the length Lm of the film boiling region LM shown in FIG. 12, the heat flux q per unit area in the contact arc Lc, and the feed speed v of the workpiece W relative to the grinding wheel T provided on the grinding machine 2. The feed speed v of the workpiece W can be acquired by the feed speed acquisition unit 211 based on the rotational speed of the workpiece motor 33.

[0082]

[0083] The burn depth estimation unit 212 estimates the grinding burn depth of the workpiece Wa based on the grinding power Q' and the film boiling boundary power Q'w, which is the burn boundary power. In this embodiment, the burn depth estimation unit 212 estimates the depth of grinding burn occurring in the workpiece Wa based on the film boiling region passing heat quantity Jm and a second correspondence relationship described below.

[0084] 6-13. Second Correspondence Relationship Storage Unit 213 The second correspondence relationship storage unit 213 stores, as the second correspondence relationship described above, a correspondence relationship between the amount of heat Jm passing through the film boiling region and the depth tb of grinding burn that occurs on the processed portion Wa due to grinding by the grinding machine 2. In this embodiment, the second correspondence relationship is a linear relationship between the amount of heat Jm passing through the film boiling region and the depth tb of grinding burn, as shown in Fig. 12, and can be expressed by the relational expression tb = aJm (a is a coefficient). Note that Fig. 13 shows the evaluation results when the processing conditions and grinding wheel sharpness shown in Fig. 10 are changed.

[0085] 13 , the second correspondence relationship creation unit 250 includes an eddy current sensor 20, an output signal acquisition unit 221, a first characteristic information acquisition unit 251, a time memory unit 252, an inflection point determination criterion memory unit 253, an inflection point calculation unit 254, a dimension information acquisition unit 204, a second characteristic information acquisition unit 255, a rotation time acquisition unit 256, an inflection point time extraction unit 257, and a burn depth calculation unit 258, all of which are configured as a storage device or a computing device. Note that, in the second correspondence relationship creation unit 250, the components that overlap with those of the grinding burn simulation unit 200 or the first correspondence relationship creation unit 220 can use the components of the grinding burn simulation unit 200 or the first correspondence relationship creation unit 220.

[0086] 1 constitutes a structural change detection unit that detects structural changes that occur in the workpiece Wa due to grinding by the grinding machine 2. In this embodiment 1, as shown in Fig. 4, the eddy current sensor 20 has a sensor head attached to the device body 171 of the sizing device 17 and is positioned on the opposite side of the grinding wheel T with respect to the workpiece W. Note that in Fig. 4, the reference numeral 20 indicates the position of the sensor head, and the sensor body is not shown.

[0087] The eddy current sensor 20 induces an eddy current inside the workpiece W using an excitation current and outputs an AC signal corresponding to the magnetic field generated by the eddy current. The eddy current sensor 20 may be configured to be able to change the phase of the output signal. In this embodiment, as shown in FIG. 14 , the eddy current sensor 20 has a coil serving as an oscillator 21, and by supplying an excitation current to the coil, an output signal is applied to a probe 22 provided at the tip of the sensor head of the eddy current sensor 20, thereby applying a magnetic field to the workpiece W and inducing an eddy current inside the workpiece W. The eddy current sensor 20 then amplifies the change in impedance acquired via the probe 22 in an amplifier 23 and inputs it to a detector 24, extracts only the frequency component of the oscillator 21, and processes the signal in a signal processor 25.

[0088] The detection unit 24 detects the signal by synchronous detection. As shown in Fig. 15, the input signal v(t) to the detection unit 24 is a signal obtained by amplifying the output of the probe 22 by the amplifier 23, and v(t) is defined by the following equation (8): where t is time, A is amplitude, f is the frequency of the oscillator 21 inside the eddy current sensor 20, and θ is the phase difference with respect to the oscillator 21 inside the eddy current sensor 20.

[0089]

[0090] Then, in the detection unit 24, v(t) that has passed through the amplification unit 23 is multiplied by a sine wave sin2πft, which has the same frequency as the frequency f of the oscillation unit 21. This is defined as x(t). Similarly, the result of multiplying by cos2πft is defined as y(t). x(t) and y(t) can be expressed as the following equations (9) and (10).

[0091]

[0092]

[0093] Next, x(t) and y(t) are passed through a low-pass filter with a sufficiently low cutoff frequency fc. Note that generally, the relationship fc<<f holds. The first terms of equations (9) and (10) are AC because they include t, but the second terms are DC because they do not include t. Therefore, after passing through the low-pass filter, equations (9) and (10) become the real axis signal X and imaginary axis signal Y shown in the following equations (11) and (12), respectively.

[0094]

[0095]

[0096] Then, A and θ of v(t) can be obtained from equations (11) and (12) as shown in the following equations (13) and (14).

[0097]

[0098]

[0099] The signal processing unit 25 performs gain and phase manipulation on the real axis signal X and imaginary axis signal Y of the detection unit 24. Therefore, the output signal of the eddy current sensor 20 is output from the detection unit 24 through the signal processing unit 25, and the frequency characteristics of the eddy current sensor 20 are the product of the frequency characteristics of the detection unit 24 and the signal processing unit 25. In general, the frequency characteristics of the signal processing unit 25 are equal to or less than the frequency characteristics of the detection unit 24. In the output signal output from the signal processing unit 25, X represents the real axis signal and Y represents the imaginary axis signal. The real axis signal X represents the real axis value of the output signal P, and the imaginary axis signal Y represents the imaginary axis value of the output signal P.

[0100] The eddy current sensor 20 is configured to supply multiple excitation currents with different frequencies to the coil. In this embodiment, the frequency of the excitation current can be set by a frequency setting unit (not shown). Since the penetration depth of the eddy current varies depending on the frequency of the excitation current, the frequency of the excitation current can be set according to the target penetration depth of the eddy current. The target penetration depth of the eddy current is set to match the surface layer where grinding burn may occur, and can be, for example, 1 to 100 μm from the machined surface, preferably 1 to 50 μm, and more preferably 10 to 30 μm. If the penetration depth is shallow, the sensitivity of the eddy current sensor becomes too high, resulting in a lower signal-to-noise ratio and reduced detection accuracy. On the other hand, if the penetration depth is deep, the detection level of the magnetic property change characteristic decreases in areas shallow from the machined surface, resulting in reduced detection accuracy.

[0101] The frequency of the excitation current according to the penetration depth can be set in the frequency band of 20 kHz to 200 MHz, preferably 100 kHz to 200 MHz, and more preferably 250 to 2500 kHz. In this embodiment, the frequency of the excitation current is set to 250 kHz so that the penetration depth of the eddy current is 30 μm.

[0102] 6-14-2. Output Signal Acquisition Unit 221 The output signal acquisition unit 221 acquires the output signal P output from the eddy current sensor 20. When expressed on a complex plane in Cartesian coordinate format, the output signal P has a value on the imaginary axis Y and a value on the real axis X, and can be expressed on the complex plane as shown in Figure 16(b) or Figure 17(b). The frequency of the excitation current output from the oscillator 21 in the eddy current sensor 20 can be adjusted by a frequency setting unit (not shown).

[0103] 6-14-3. First Feature Information Acquisition Unit 251 The first feature information acquisition unit 251 acquires first feature information. The first feature information is information that links at least one of the imaginary axis value and real axis value when the output signal P acquired by the output signal acquisition unit 221 is represented on a complex plane in the form of a Cartesian coordinate system with time information that is the time when the workpiece W is ground. In this embodiment, both the imaginary axis value and the real axis value of the output signal P represented on the complex plane shown in FIG. 16(b) are linked to the elapsed time from the start of grinding, which is measured by the time memory unit 252 described below.

[0104] 6-14-4. Time Memory Unit 252 The time memory unit 252 measures the elapsed time from the start time T0 of the grinding process. In this embodiment, the grinding process S1 of the workpiece W includes a rough grinding process S11, a fine grinding process S12, a fine grinding process S13, and a spark-out process S14, as shown in Fig. 23. Each process will be described later.

[0105] 6-14-5. Inflection Point Judgment Criterion Storage Unit 253 The inflection point judgment criterion storage unit 253 pre-stores inflection point judgment criteria for determining whether the output signal represented on the complex plane has reached an inflection point, described below, for each excitation current frequency. In this embodiment, the inflection point judgment criterion can be created based on the correspondence between the frequency of the excitation current, first characteristic information acquired by applying an excitation current having that frequency to a workpiece for creating an inflection point judgment criterion during machining, and the grinding burn state of the workpiece for creating an inflection point judgment criterion. The workpiece for creating an inflection point judgment criterion has the same shape and material as the workpiece W to be evaluated, as shown in FIG. 1.

[0106] Regarding the inflection point determination criteria, for example, the correspondence relationship between the first feature information and the grinding burn state when the excitation current frequency is 250 kHz is shown in Figures 16(a) and 16(b), and the correspondence relationship between the first feature information and the grinding burn state when the excitation current frequency is 1000 kHz is shown in Figures 17(a) and 17(b). Comparing the case where the excitation current frequency is 250 kHz with the case where the excitation current frequency is 1000 kHz, the correspondence relationship shown on the complex plane for the case where the excitation current frequency is 1000 kHz is expressed as a shape rotated -90 degrees from the case where the excitation current frequency is 250 kHz.

[0107] Next, the locus of the output signal P on the complex plane will be described with reference to Fig. 16(b). On the complex plane shown in Fig. 16(b), the output signal P output from the eddy current sensor 20 is plotted at the position indicated by the symbol A1 at the start of grinding. Thereafter, in the rough grinding step S11, grinding burn occurs on the workpiece W, and the magnetic characteristics change accordingly. As a result, the output signal P decreases in value on the real axis on the complex plane and slightly increases in value on the imaginary axis over time. Thereafter, the real axis value decreases and the imaginary axis value decreases, and then the real axis value increases and the imaginary axis value decreases, until the position indicated by the symbol A2 is reached, at which point the rough grinding step S11 is completed.

[0108] Thereafter, when the fine grinding process S12 begins, as grinding burns (process-affected layer, softened layer) that had occurred on the workpiece W are gradually removed, the output signal P in the complex plane decreases in value on the real axis and gradually increases in value on the imaginary axis. That is, near the start point B1 of the fine grinding process S12, the vector direction in the imaginary axis direction in the locus of the output signal P in the complex plane is pointing upward. Thereafter, as grinding progresses further and the position indicated by reference symbol B2 is reached, the value on the real axis increases but the value on the imaginary axis continues to gradually increase. Then, at the position indicated by reference symbol B3, the value on the real axis continues to increase but the value on the imaginary axis decreases. That is, at reference symbol B3, the output signal P reaches its maximum value in the fine grinding process S12, and thereafter the vector direction in the imaginary axis direction in the locus of the output signal P in the complex plane changes to a downward direction. Thereafter, the value on the real axis increases while the value on the imaginary axis decreases until the position indicated by reference symbol B4 is reached and the rough grinding process S11 is completed.

[0109] 6-14-6. Inflection Point Calculation Unit 254 The inflection point calculation unit 254 calculates an inflection point based on inflection point determination criteria. An inflection point indicates a point at which the vector direction of the output signal P changes in the complex plane in the imaginary axis direction or the real axis direction. Therefore, when the frequency of the excitation current shown in FIG. 16(b) is 250 kHz, point B3 at which the vector direction of the output signal P changes from upward to downward in the imaginary axis direction is represented as an inflection point. Note that even when the frequency of the excitation current shown in FIG. 17(b) is 1000 kHz, the point at which the vector direction of the output signal P changes from downward to upward in the imaginary axis direction is represented as inflection point B3.

[0110] Since the locus of the output signal P in the complex plane changes depending on the frequency of the excitation current, the inflection point determination criterion for the inflection point also changes. In this embodiment, the inflection point determination criterion storage unit 253 stores the locus of the output signal P in the complex plane for each excitation current frequency for the workpiece used to create the inflection point determination criterion (master), and based on this, the inflection point determination criterion is stored for each excitation current frequency. For example, as described above, the inflection point determination criterion for a 250 kHz excitation current frequency is such that the inflection point is determined to be the point at which the direction of the vector of the locus of the output signal P stored in the inflection point determination criterion storage unit 253 shown in Figure 16(b) changes from upward to downward in the imaginary axis direction in the fine grinding process S12. Furthermore, the inflection point determination criterion when the frequency of the excitation current is 1000 kHz is that the inflection point is the point at which the direction of the vector of the trajectory of the output signal P stored in the inflection point determination criterion memory unit 253 shown in Figure 17(b) changes from downward to upward in the imaginary axis direction in the fine grinding process S12.

[0111] Furthermore, the inflection point judgment criterion storage unit 253 also stores the correspondence between the first characteristic information and the grinding burn state for the workpiece used to create the inflection point judgment criterion. When the excitation current frequency is 250 kHz as shown in FIG. 16( b), in the precision grinding process S12, the region from the precision grinding process start point B1 to the inflection point B3 indicates a state in which a softened layer that will cause grinding burn is present on the workpiece W. The region from the inflection point B3 to the vicinity of the processing end point B4 indicates a state in which no softened layer is present on the workpiece W, but a retained austenite-reduced layer that had formed deeper on the softened layer remains on the workpiece W. Note that the retained austenite-reduced layer has mechanical properties closer to the base material than the softened layer, and is therefore not included in the grinding burn. Furthermore, at the processing end point B4, there is no retained austenite-reduced layer. This is also true when the excitation current frequency is 1000 kHz as shown in FIG. 17( b).

[0112] 14 acquires dimensional information of the workpiece W as described above, and in this embodiment, the sizing device 17 can detect the dimensions of the workpiece W during machining. Note that instead of using the sizing device 17, the dimensional information of the workpiece W may be indirectly calculated and acquired based on the coordinate position of the Z axis, which is the cutting axis of the workpiece W, output from the control unit 300.

[0113] 14 acquires second feature information. The second feature information is information that links the dimension information acquired by the dimension information acquisition unit 204 with time information.

[0114] 6-14-8. Rotation Time Acquisition Unit 256 The rotation time acquisition unit 256 shown in FIG. 14 stores, as rotation times, the times acquired for each rotation of the workpiece W, or for a predetermined number of rotations, from the end time of the rough grinding step S11. In this embodiment, the times acquired for each rotation of the workpiece W, from the end time of the rough grinding step S11, are stored as rotation times. In the grinding process S1, grinding burn occurs in the rough grinding step S11, which has high grinding efficiency. Therefore, the workpiece ground by the grinding wheel T at the end time of the rough grinding step S11 has the greatest burn depth, which is the depth of grinding burn. The rotation times correspond to the times of the bottoms of the valleys repeatedly appearing in the real axis signal in FIG. 16(a). The lower envelope is drawn by connecting the bottoms of the valleys.

[0115] 14 extracts, from the first feature information, times at which inflection points appear in the trajectory of the output signal represented on the complex plane, as inflection point times. In this embodiment, the inflection point times are extracted from the multiple rotation times acquired by the rotation time acquisition unit 256. For example, in FIGS. 16(a) and 17(a), the inflection point time extraction unit 257 extracts the time at which inflection point B3 appears as inflection point time T2.

[0116] 14 calculates the grinding burn depth of the processed portion of the workpiece W based on the inflection point time extracted by the inflection point time extraction unit 257. As shown in Fig. 18, in the dimensional information of the workpiece W from the grinding start time T0 to the grinding end time Te, the grinding burn depth tb at the rough grinding step end time T1 is calculated as the difference D1 between the dimensional information at the rough grinding step end time T1 and the dimensional information at the inflection point time T2.

[0117] In parallel with the calculation of the grinding burn depth tb in the second correspondence relationship creation unit 250, the heat quantity Jm passing through the film boiling region is calculated as described above by the heat quantity calculation unit 210 shown in Fig. 3. Then, by changing the grinding conditions and obtaining a plurality of relationships between the grinding burn depth tb and the heat quantity Jm passing through the film boiling region, a second correspondence relationship approximated by a straight line as shown in Fig. 13 is created, and this is stored in the above-mentioned second correspondence relationship storage unit 213 shown in Fig. 14.

[0118] 1 combines the estimation result of the machining shape estimation unit 111 in the machining shape simulation unit 100 and the estimation result of the burn depth estimation unit 212 in the grinding burn simulation unit 200 based on time-series information. That is, the estimation result combination unit 301 combines the estimation result of the machining shape estimation unit 111 and the estimation result of the burn depth estimation unit 212 at the same time. In this embodiment, the estimation result of the machining shape estimation unit 111 shown in Fig. 19(a) and the estimation result of the burn depth estimation unit 212 shown in Fig. 19(b) are combined at the same time.

[0119] 8. Combined Result Display Unit 302 The combined result display unit 302 displays the combined results of the estimation result combining unit 301. There are no limitations on the display format of the combined results, but in this embodiment, as shown in Figures 20(a) to 20(f), a format is adopted in which the machined shape Ws and the burn depth Wd at each machining position are displayed on polar coordinates. In Figure 20(a), Wo represents the grinding start position for each phase. In Figures 20(a) to 20(f), the machined shape Ws represents a value obtained by calculating the difference from the average radius of the workpiece W and adding 50 μm to this, which makes it easier to visually recognize the difference between the machined shape Ws and a perfect circle.

[0120] Figures 20(a) to (f) correspond to times a to f in Figure 19, with Figure 20(a) showing the combined results for the initial time of the rough grinding step S11, Figure 20(b) showing the time in the middle of the rough grinding step S11, Figure 20(c) showing the time at the end of the rough grinding step S11 (the start of the fine grinding step S12), Figure 20(d) showing the time in the middle of the fine grinding step S12, Figure 20(e) showing the time at the end of the fine grinding step S12 (the start of the fine grinding step S13), and Figure 20(f) showing the time at the end of the fine grinding step S13 (the start of the spark-out step S14). Figures 20(a) to (f) show an example in which a high-rigidity material with a relatively high rigidity is used as the workpiece W, and Figures 21(a) to (f) show an example in which a low-composite material with a relatively low rigidity is used as the workpiece W.

[0121] 9. Machining Condition Evaluation Unit 303 The machining condition evaluation unit 303 evaluates the quality of the machining conditions for the workpiece W based on the estimation result of the machining shape estimation unit 111. In this embodiment, the machining condition evaluation unit 303 can determine that the machining conditions are good when the burn depth at the end of machining is 0, and can determine that the machining conditions are bad when the burn depth at the end of machining is greater than 0.

[0122] 1 calculates the remaining machining allowance of the workpiece W for each time series based on the combination result by the estimation result combination unit 301 and the target shape of the workpiece W. The remaining machining allowance can be expressed as the difference between the target shape of the workpiece W and the dimensional information of the workpiece W for each time series. The remaining machining allowance display unit 305 then displays the remaining machining allowance calculated by the remaining machining allowance calculation unit 304. The display format of the remaining machining allowance display unit 305 is not limited and can be set appropriately. For example, the display result of the remaining machining allowance display unit 305 is shown in FIG. 22.

[0123] 11. Description of Grinding Process S1 The grinding process S1 will be described with reference to Fig. 23. As described above, the grinding process S1 performed by the grinding machine 2 includes a rough grinding step S11, a fine grinding step S12, a fine grinding step S13, and a spark-out step S14.

[0124] In the rough grinding step S11, the control unit 300 rotates the grinding wheel T at a predetermined speed based on operation command data such as the shape of the workpiece W, grinding conditions, the shape of the grinding wheel T, and coolant flow rate or supply timing information, to grind the workpiece W with a first depth of cut. In the fine grinding step S12, the control unit 300 grinds the workpiece W with a second depth of cut that is smaller than the first depth of cut. In the fine grinding step S13, the control unit 300 grinds the workpiece W with a third depth of cut that is smaller than the second depth of cut. In the spark-out step S14, the workpiece W is rotated at a preset rotation speed to grind away the portion left unground in the fine grinding step S13, resulting in a perfectly circular cross-sectional shape. The depth of cut in the spark-out step S14 can be set to zero.

[0125] The cutting depth can be adjusted by controlling the cutting position of the grinding wheel T with the control unit 300. The first to third cutting depths in each of steps S11 to S13 are appropriately set within a range that satisfies the above-mentioned relationship, and the actual cutting depth in the spark-out step S14 is substantially zero. The first cutting depth in the rough grinding step S11 is the largest, and the rough grinding step S11 has the highest grinding efficiency among steps S11 to S14. Therefore, grinding burn occurs substantially only in the rough grinding step S11.

[0126] 12. Machining Shape Estimation Processing by Machining Shape Simulation Unit 100 The machining shape estimation processing S2 by the machining shape simulation unit 100 in this embodiment will be described with reference to the flow shown in Fig. 24. First, in step S21, a machine model 2 of the machine tool created in advance is stored in the machine model storage unit 2a as a preparation step. Also, the shape of the workpiece W is stored in the workpiece shape storage unit 101. Also, an object for which a machining result is to be estimated is set in the estimation object setting unit 106. In this embodiment 1, the roundness of the cylindrical workpiece W is set as the estimation object. Also, machining conditions for the machine model 2 are input to the machining condition storage unit 104.

[0127] 2, the stiffness of the machine model 2 is calculated. The calculated stiffness is stored in the stiffness storage unit 102. After that, in step S23, a command value based on the machining conditions stored in the machining condition storage unit 104 is stored in the command value storage unit 103. Note that steps S22 and S23 may be performed in parallel.

[0128] Then, in step S24, the vibrations generated by the vibration generating unit 4 are acquired and stored as vibration information in the vibration information storage unit 105. In the first embodiment, vibration information of the vibrations generated by the Z-axis motor 12b, the X-axis motor 14b, the workpiece motor 33, the grinding wheel motor 53, and the pump 60 is stored.

[0129] Thereafter, in step S25, the design information similarity evaluation unit 108 evaluates the similarity between the design information constituting the correspondence stored in the vibration correspondence storage unit 107 and the design information of the machine tool in the machine model 2. In step S26, the generated vibration identification unit 109 identifies the vibration generated from the vibration generating unit 4 in the correspondence based on the design information evaluated to have high similarity based on the evaluation result of the design information similarity evaluation unit 108.

[0130] Next, in step S27, the machine behavior estimation unit 110 estimates the machine behavior including the static behavior based on the command values ​​and design information and the dynamic behavior based on the identified vibration. Then, in step S28, the machining shape estimation unit 111 estimates the machining result of the estimation target based on the estimation result of the machine behavior estimation unit 110. Based on the estimation result, the shape of the workpiece W stored in the workpiece shape storage unit 101 is updated in order to estimate the next machining result. In this embodiment 1, as shown in Fig. 19(b), a time-series change in the shape of the workpiece W is estimated based on the estimation result of the machine behavior. Then, the process ends.

[0131] 13. Burn Depth Estimation Process S3 by Grinding Burn Simulation Unit 200 Next, the burn depth estimation process S3 by the grinding burn simulation unit 200 will be described with reference to the flowcharts in Figures 25 and 26. In the grinding burn state estimation process S3, first, in step S31, the coolant power calculation unit 227 acquires the coolant power Qa. Next, in step S32, the coolant temperature acquisition unit 228 and the coolant flow rate acquisition unit 229 acquire the coolant temperature Ta and the coolant flow rate Fa, and the dimension information acquisition unit 204 acquires the dimensions of the workpiece W.

[0132] In step S33, the grinding power calculation unit 203 calculates the grinding power Q' as the product of the tangential resistance Ft calculated by the tangential resistance calculation unit 202 and the relative rotation speed V+v based on the rotation speed V of the grinding wheel T and the rotation speed v of the workpiece W. Then, in step S34, the grinding wheel sharpness calculation unit 226 acquires the grinding wheel sharpness K.

[0133] Thereafter, in step S35, the contact arc length acquisition unit 206 acquires the contact arc length Lc at the machined portion Wa of the workpiece W. Thereafter, in step S36, the contact arc heat flux calculation unit 207 calculates the contact arc heat flux q.

[0134] Then, in step S37, the film boiling boundary power acquisition unit 205 calculates the film boiling boundary power Q'w based on the grinding power Q', the contact arc heat flux q, the contact arc length Lc, and the first correspondence relationship. Note that the film boiling boundary power Q'w is calculated by reflecting Ta, Fa, Qa, and K by the cooling state reflection unit 230.

[0135] Next, in step S38, the film boiling region length calculation unit 209 calculates the length Lm of the film boiling region LM using the film boiling boundary power Q'w, the grinding power Q', and the contact arc length Lc. Then, in step S39, the burn depth estimation unit 212 determines whether or not Lm > 0 is satisfied. If Lm > 0 is not satisfied, the process proceeds to No in step S39, and in step S40, the burn depth estimation unit 212 evaluates that no grinding burn has occurred in the processed portion Wa. On the other hand, if Lm > 0 is satisfied, the process proceeds to Yes in step S39. Then, in step S41 shown in FIG. 26, the burn depth estimation unit 212 evaluates that grinding burn has occurred in the processed portion Wa.

[0136] Thereafter, in step S42, the feed rate acquisition unit 211 acquires the feed rate v of the workpiece W. Then, in step S43, the passed heat amount calculation unit 210 calculates the amount of heat Jm passed through the film boiling region based on the contact arc heat flux q, the length Lm of the film boiling region LM, and the feed rate v of the workpiece W. Next, in step S44, the burn depth estimation unit 212 estimates the burn depth tb based on the amount of heat Jm passed through the film boiling region and the second correspondence relationship. Then, the process ends.

[0137] 14. Estimation Result Combining Process and Remaining Machining Allowance Calculation Process S4 Next, the estimation result combining process S4 by the estimation result combining unit 301 will be described with reference to the flowchart of Fig. 27. In the estimation result combining process S4, first, in step S45 of Fig. 27, the estimation result combining unit 301 combines the estimation result of the machining shape estimating unit 111 in the machining shape simulation unit 100 and the estimation result of the burn depth estimating unit 212 in the grinding burn simulation unit 200 based on time-series information. In this embodiment, the estimation result of the machining shape estimating unit 111 shown in Fig. 19(a) and the estimation result of the burn depth estimating unit 212 shown in Fig. 19(b) are combined at the same time.

[0138] Thereafter, in step S46, the combined result of the estimation result combining unit 301 is displayed by the combined result display unit 302. In this embodiment, the combined result is displayed using a polar coordinate system, as shown in Figures 20(a) to 20(f). Next, in step S47, the remaining machining allowance calculation unit 304 calculates the remaining machining allowance as the difference between the target shape of the workpiece W and the dimensional information of the workpiece W in each time series. Thereafter, in step S48, the remaining machining allowance display unit 305 displays the remaining machining allowance calculated by the remaining machining allowance calculation unit 304, as shown in Figure 22. Then, the process ends.

[0139] 15. Actions and Effects The actions and effects of the machining result estimating device 1 of this embodiment 1 are described below. According to this embodiment 1, the machining shape is estimated based on the estimation result of the machine behavior of the machine tool. Furthermore, the tangent resistance Ft of the machining point is obtained based on the removed volume of the workpiece W calculated from the estimation result of the machining shape, and the grinding power Q' for each time series is calculated based on the tangent resistance Ft, the rotational speed V of the tool T, and the rotational speed v of the workpiece W. Then, the grinding burn depth is estimated based on the grinding power Q' and the film boiling boundary power Q'w, which is the burn boundary power. As a result, both the machining shape and the burn depth can be estimated, thereby improving the estimation accuracy of the machining result.

[0140] This embodiment also includes an estimation result combining unit 301 that combines the estimation results of the machining shape estimating unit 111 and the sear depth estimating unit 212 based on time-series information, and a combined result display unit 302 that displays the combined results of the estimation result combining unit 301. This makes it easier for the user to simultaneously recognize the estimation results of the machining shape estimating unit 111 and the sear depth estimating unit 212.

[0141] In this embodiment, the combined result display unit 302 displays the combined result by the estimation result combining unit 301 in polar coordinates. This allows the user to more easily recognize the estimation result by the machining shape estimating unit 111 and the estimation result by the burn depth estimating unit 212 simultaneously.

[0142] Furthermore, this embodiment includes a remaining machining allowance calculation unit 304 that calculates the remaining machining allowance of the workpiece W in each time series based on the combination result by the estimation result combination unit 301 and the target shape of the workpiece W, and a remaining machining allowance display unit 305 that displays the remaining machining allowance calculated by the remaining machining allowance calculation unit 304. This makes it easier for the user to recognize the remaining machining allowance.

[0143] Furthermore, in this embodiment, the machine model storage unit 2a stores a machine model 2 that models the machine tool including a vibration generating unit that generates vibrations, and is equipped with a vibration information storage unit 105 that stores vibration information based on vibrations generated from the vibration generating unit 4, and the machine behavior estimation unit 110 estimates dynamic behavior based on the vibration information. As a result, the estimated machining result is based on machine behavior that includes dynamic behavior that takes into account vibrations from the vibration generating unit 4 provided in the machine tool, in addition to static behavior that does not take into account vibrations from the vibration generating unit 4, so it is possible to obtain estimation results with higher accuracy than conventional methods. Furthermore, since there is no need to use an actual machine tool or a prototype, it is possible to shorten the lead time for designing and developing the machine tool and significantly reduce prototyping costs.

[0144] Furthermore, this embodiment includes a film boiling boundary power acquisition unit 205 that acquires a film boiling boundary power Q'w corresponding to the grinding power required for the coolant CL supplied to the workpiece Wa to reach a film boiling state when the workpiece Wa is ground by the machine tool 2, and the burn depth estimation unit 212 estimates the grinding burn depth based on the film boiling boundary power Q'w as the burn boundary power and the grinding power Q' calculated by the grinding power calculation unit 203. As a result, by creating the first correspondence relationship in advance, the film boiling boundary power Q'w can be acquired with a simple configuration, and there is no need to acquire the temperature of the workpiece Wa, so that the grinding burn depth can be estimated with high accuracy taking into account the coolant CL reaching a film boiling state in the workpiece Wa.

[0145] Furthermore, this embodiment includes a contact arc length acquisition unit 206 that acquires the length Lc of the contact arc LC between the tool and the workpiece in a cross section perpendicular to the main axis of the tool T, a contact arc heat flux calculation unit 207 that calculates the heat flux q at the contact arc LC, and a first correspondence relationship storage unit 208 that stores a first correspondence relationship that is a correspondence relationship between the length Lw of the non-film boiling region LW that is a region at the contact arc Lc that has not yet reached a film boiling state, the heat flux qw generated in the non-film boiling region LW by grinding, and the film boiling boundary power Q'w, and the film boiling boundary power acquisition unit 205 acquires the film boiling boundary power Q'w with a simple configuration based on the first correspondence relationship created in advance and the heat flux q at the contact arc Lc.

[0146] As described above, according to this embodiment, it is possible to provide the machining result estimating device 1 that has excellent estimation accuracy of the machining result by the machine tool 2.

Claims

1. A machining result estimation device for estimating machining results when a workpiece is machined by a tool provided on a machine tool, comprising: a machine model storage unit for storing a machine model that models the machine tool; an estimation target setting unit for setting an estimation target for the machining result of the workpiece; a machine behavior estimation unit for estimating machine behavior including static behavior of the machine model based on command values ​​based on machining conditions of the machine tool and design information of the machine tool in the machine model, and dynamic behavior of the machine model according to the estimation target; a machined shape estimation unit for estimating a machined shape of the workpiece that is the estimation target based on the estimation result of the machine behavior estimation unit; a removed volume calculation unit for calculating a removed volume removed from the workpiece by the tool in each time series based on the estimation result of the machined shape estimation unit; a tangential resistance calculation unit for calculating a tangential resistance at a machined portion of the workpiece in each time series based on the removed volume calculated by the removed volume calculation unit; and a grinding power calculation unit for calculating grinding power in each time series based on the tangential resistance calculated by the tangential resistance calculation unit, the rotational speed of the tool, and the rotational speed of the workpiece. and a burn depth estimation unit that estimates a grinding burn depth that will occur in the workpiece, based on the grinding power calculated by the grinding power calculation unit and a burn threshold power that is the maximum value of power required to rotate the tool within a range in which grinding burn will not occur in the workpiece.

2. The processing result estimation device according to claim 1, comprising: an estimation result combining unit that combines the estimation results of the processing shape estimation unit and the estimation results of the burn depth estimation unit based on time-series information; and a combined result display unit that displays the combined results of the estimation result combining unit.

3. The processing result estimation device according to claim 2, wherein the connection result display unit displays the connection result in polar coordinates.

4. A machining result estimation device as described in claim 2 or 3, comprising: a remaining machining allowance calculation unit that calculates the remaining machining allowance of the workpiece in each time series based on the combination result by the estimation result combination unit and the target shape of the workpiece; and a remaining machining allowance display unit that displays the remaining machining allowance calculated by the remaining machining allowance calculation unit.

5. The machining result estimation device according to any one of claims 1 to 3, wherein the machine model storage unit stores a machine model of the machine tool including a vibration generating unit that generates vibrations, and the device is equipped with a vibration information storage unit that stores vibration information based on vibrations generated from the vibration generating unit, and the machine behavior estimation unit estimates the dynamic behavior based on the vibration information.

6. A machining result estimation device according to any one of claims 1 to 3, comprising a film boiling boundary power acquisition unit that acquires film boiling boundary power equivalent to the grinding power required for the coolant supplied to the workpiece to reach a film boiling state when the workpiece is ground by the machine tool, and the burn depth estimation unit estimates the grinding burn depth based on the film boiling boundary power as the burn boundary power and the grinding power calculated by the grinding power calculation unit.

7. A machining result estimating device according to claim 6, comprising: a contact arc length acquiring unit that acquires the length of a contact arc between the tool and the workpiece in a cross section perpendicular to the main axis of the tool; a contact arc heat flux calculating unit that calculates a heat flux in the contact arc; and a first correspondence relationship storing unit that stores a first correspondence relationship between the length of a non-film boiling region in the contact arc that has not yet reached a film boiling state, the heat flux generated in the non-film boiling region by the grinding, and the film boiling boundary power, wherein the film boiling boundary power acquiring unit acquires the film boiling boundary power based on the first correspondence relationship and the heat flux in the contact arc.

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