Vibration characteristic estimation system in a machine tool, machine tool and vibration characteristic estimation method

Abstract

A vibration characteristic estimation system (21) in a machine tool (m) for machining by relative movement of a tool (6) and a workpiece (8) comprises: a first vibration characteristic acquisition unit (22) that obtains a first vibration characteristic based on an output from a sensor (9); a machine information acquisition unit (23) that obtains machine information; a gripper tool information acquisition unit (24) that obtains gripper tool information; a machined section information acquisition unit (25) that obtains at least one piece of tool information and one piece of workpiece information; a compensation factor acquisition unit (27) that obtains a compensation factor based on at least one piece of machine information, gripper tool information, tool information, and workpiece information;and a second vibration characteristic estimation unit (28) which estimates a second vibration characteristic by compensating the first vibration characteristic using the compensation factor, wherein the second vibration characteristic is based on an extent of vibration at the processing point when an excitation force is applied.

Description

[0001] The invention relates to a vibration characteristic estimation system for estimating vibration characteristics in a machine tool, the machine tool and a vibration characteristic estimation method.

[0002] To perform highly efficient and highly accurate cutting work with a machine tool, it is necessary to select appropriate cutting conditions considering the vibration characteristics of a system including the machine tool, tools, and a workpiece. For example, JP 2020-80015 A discloses a vibration characteristic estimation method for estimating the vibration characteristics of a system using a vibration measurement result during actual machining. In this method, the vibration characteristic is calculated from the measurement result of vibration during machining at a target point, such as a tool tip, where the vibration characteristic is desired to be estimated. In the disclosure, an accelerometer, such as a sensor, is attached to the tool tip to measure the vibration.However, when the above method is performed in actual workplaces, a variety of tools are used by each operator depending on the case, and an operator is required to determine the mounting position of the accelerometer on a tool and is also required to check whether the mounting condition is suitable for estimating the vibration characteristic.

[0003] Another vibration characteristic estimation method for estimating the vibration characteristics of a system is disclosed in JP 2012-187691 A. In the disclosed method, an accelerometer, such as a sensor, is mounted in advance at a predetermined position on a machine tool. The sensor mounted at the predetermined position measures a natural frequency and obtains natural vibration characteristics via an analytical value, which is an operation value. Then, a desired vibration characteristic is estimated using a compensated analytical value for the natural vibration characteristics. To compensate for the analytical value, the difference between the analytical value of the natural frequency of the main spindle system equipped with a reference tool and a measured value is used as a compensation value.Therefore, the vibration characteristic can be estimated at a desired estimation target point where it is difficult to mount a sensor. On the other hand, in the case of a complex system such as a machine tool, a plurality of natural frequencies exist, and the analytical value of each of the plurality of natural frequencies and a measured value are adjusted in descending frequency order. Each compensation value corresponding to the plurality of natural frequencies is calculated from the adjusted analytical value and a measured value.

[0004] Therefore, in a situation where the used tool and the reference tool differ significantly, the method disclosed in JP 2012-187691 A may cause a difference in the order of natural frequency matching and vibration behavior between a reference tool and a used tool. Accordingly, even if the compensation value calculated using the reference tool is applied to a system equipped with the used tool, it may not be possible to appropriately estimate the natural frequency.

[0005] In view of the above, a vibration characteristic estimation method for estimating a vibration characteristic of an estimation object to which it is difficult to mount a sensor with high accuracy by compensating a vibration characteristic estimated at a predetermined position of a machine tool where it is easy to mount a sensor has been desired.

[0006] Therefore, the invention was made in view of the problem described above, and it is an object of the invention to provide a vibration characteristic estimation system in a machine tool, the machine tool, and a vibration characteristic estimation method that can estimate a vibration characteristic at a target point where it is difficult to attach a sensor with high accuracy by compensating a vibration characteristic at a sensor attachment position of the machine tool.

[0007] The object is achieved by a vibration characteristic estimation system according to claim 1, a machine tool according to claim 4, and a vibration characteristic estimation method according to claim 5. Advantageous further developments are contained in the dependent claims.

[0008] To achieve the above-described object, a first configuration of this invention is a vibration characteristic estimation system in a machine tool for machining by relatively moving a tool and a workpiece. The vibration characteristic estimation system includes a first vibration characteristic acquisition unit, a machine information acquisition unit, a gripping tool information acquisition unit, a machined portion information acquisition unit, a compensation factor storage unit, a compensation factor acquisition unit, and a second vibration characteristic estimation unit. The first vibration characteristic acquisition unit acquires a first vibration characteristic based on an output of a sensor attached to the machine tool when an excitation force is applied to a machining point as a contact point between the tool and the workpiece during machining.The machine information acquisition unit acquires machine information including at least one of a name, an axis configuration, and component information of the machine tool, and attachment position information of the sensor. The gripping tool information acquisition unit acquires gripping tool information including at least one of a name, a dimension, and a material of a gripping tool that grips the tool or the workpiece, and a gripping method of the tool or the workpiece. The machined portion information acquisition unit acquires at least one of tool information and workpiece information. The tool information includes at least one of a name, a dimension, and a material of the tool. The workpiece information includes at least one of a name, a dimension, and a material of the workpiece.The compensation factor storage unit stores a compensation factor representing a relationship between the first vibration characteristic and a second vibration characteristic, in association with at least one of the machine information, the gripping tool information, the tool information, and the workpiece information. The second vibration characteristic is based on a magnitude of vibration at the machining point when an excitation force is applied to the machining point. The compensation factor acquisition unit acquires the compensation factor based on at least one of the machine information, the gripping tool information, the tool information, and the workpiece information, from the compensation factor storage unit.The second vibration characteristic estimation unit estimates the second vibration characteristic by compensating the first vibration characteristic obtained by the first vibration characteristic obtaining unit using the compensation factor obtained by the compensation factor obtaining unit. The compensation factor is configured as a function based on the machine information and a frequency associated with the machine information. The frequency is obtained from the sensor.

[0009] According to another aspect of the first configuration of this invention, which is in the configuration described above, the compensation factor includes a constant associated at least with the tool information.

[0010] According to yet another aspect of the first configuration of this invention included in the configuration described above, the compensation factor is a frequency function associated with at least the machine information.

[0011] In order to achieve the above-described object, a second configuration of this invention is a machine tool including the above-described vibration characteristic estimation system.

[0012] To achieve the above-described object, a third configuration of this invention is a vibration characteristic estimation method in a machine tool for machining by relatively moving a tool and a workpiece. The vibration characteristic estimation method includes: obtaining a first vibration characteristic based on an output of a sensor mounted on the machine tool when an excitation force is applied to a machining point of the tool or the workpiece as a contact point between the tool and the workpiece during machining; obtaining machine information including at least one of a name, an axis configuration, and component information of the machine tool, and mounting position information of the sensor;Obtaining gripping tool information including at least one of a name, a dimension, and a material of a gripping tool that grips the tool or the workpiece, and a gripping method of the tool or the workpiece; Obtaining at least one of tool information and workpiece information included in the machined portion information, wherein the tool information includes at least one of a name, a dimension, and a material of the tool, and the workpiece information includes at least one of a name, a dimension, and a material of the workpiece;Obtaining a compensation factor that is a ratio between the first vibration characteristic and a second vibration characteristic based on at least one of the machine information, the gripping tool information, the tool information, and the workpiece information, wherein the second vibration characteristic is based on an amount of vibration at the machining point when the excitation force is applied to the machining point; and estimating the second vibration characteristic by compensating the first vibration characteristic obtained in obtaining the first vibration characteristic using the compensation factor obtained in obtaining the compensation factor. The compensation factor is formed based on the machine information and a frequency associated with the machine information. The frequency is obtained from the sensor.

[0013] According to the invention, a vibration characteristic at a desired point in a machine tool where it is difficult to mount a sensor can be estimated with high accuracy by compensating a vibration characteristic at a point where the sensor is easily mountable based on at least one of the machine information, the gripping tool information, the tool information, or the workpiece information.

[0014] In addition, even if a compensation factor of a vibration characteristic has not been obtained for an estimation target point, the vibration characteristic at the target point can be estimated using an obtained compensation factor. Fig. 1 is a schematic configuration diagram illustrating a vibration characteristic estimation system in a machine tool; Fig. 2 is a flowchart illustrating an estimation method of a second vibration characteristic; Fig. 3 is a diagram illustrating an example of measurement of a first vibration characteristic and a second vibration characteristic; Fig. 4 is a diagram showing an example of a compensation factor; Fig. 5 is a comparison between a direct measurement result and an estimation result of the second vibration characteristic; and Fig. 6 is a comparison between a result of a direct measurement and an estimation result of the second vibration characteristic.

[0015] The following describes an embodiment of the invention based on the drawings.

[0016] Fig. 1 is a schematic configuration diagram of a machining center, which is an exemplary machine tool.

[0017] A main spindle housing 3 of a machining center m includes a main spindle 4 rotatable by a main spindle motor. A tool 6 gripped by a holder 5 is attached to the distal end of the main spindle 4. The main spindle housing 3, as a moving body, is movable in a Z-axis direction relative to a column 2 attached to a bed 1 via a Z-axis ball screw by a Z-axis motor. An acceleration sensor 9, as a sensor that detects vibration of the machining center m, is attached to the main spindle housing 3. A workpiece 8 is mounted on a workpiece table 7 as a moving body. The workpiece table 7 is movable in mutually perpendicular X-axis and Y-axis directions on the bed 1.The movement of the workpiece table 7 in the X-axis direction is performed via an X-axis ball screw by an X-axis motor, and the movement in the Y-axis direction is performed via a Y-axis ball screw by a Y-axis motor.

[0018] An NC device 11 that controls the machining center m includes a machine operation command unit (not shown) that controls the main spindle motor and each of the feed-axis motors based on a program input from an operator, and commands the rotation of the tool 6 and the relative movement of the tool 6 and the workpiece 8 to perform cutting work. The NC device 11 includes a CPU and a memory connected to the CPU, and implements operations using them.

[0019] A vibration characteristic estimation system 21 includes a first vibration characteristic acquisition unit 22, a machine information acquisition unit 23, a gripping tool information acquisition unit 24, and a machined portion information acquisition unit 25. The vibration characteristic estimation system 21 is arranged as a computer included in the NC device 11 or in a separate computer and is electrically connected to the machining center m. The first vibration characteristic acquisition unit 22 calculates and acquires a relationship between the vibration amount of the main spindle housing 3 and an excitation force applied to a machining point, namely, a compliance. The machining point is a contact point between the tool 6 and the workpiece 8 during machining, that is, a tip of the tool 6 that performs machining.The ratio of the vibration magnitude of the main spindle housing 3 to the excitation force applied to the tip of the tool 6 performing machining is a first vibration characteristic in the embodiment. In calculating the first vibration characteristic, the excitation force applied to the tip of the tool 6 is an output, namely a detected value, of a hammer when the tip of the tool 6 is excited by the hammer with a built-in load sensor, and the vibration magnitude of the main spindle housing 3 is an output, namely a detected value, of the acceleration sensor 9. In addition, as disclosed in JP 2020-80015 A, the first vibration characteristic can be calculated by analyzing the vibration detected by the acceleration sensor 9 during machining.

[0020] The machine information acquisition unit 23 acquires machine information from a machine information storage unit 13 included in the NC device 11, which stores the machine information. In the invention, the machine information refers, in addition to the machine name, to various types of information related to the machining center m for identifying how vibration propagates from the main spindle 4 of the machining center m to the acceleration sensor 9, such as an axis configuration, component information, a part coupling method, and a mounting position of the acceleration sensor 9.

[0021] The gripping tool information acquisition unit 24 acquires gripping tool information from a gripping tool information storage unit 14 included in the NC device 11, which stores the gripping tool information. In the invention, the gripping tool information refers to various types of information, including dimensions of the holder 5, such as a diameter DH and a length LH; a method for gripping the tool 6 by the holder 5, such as a position, a gripping force, and a gripping direction; and a material of the holder 5, in addition to the name of the holder 5.

[0022] The machined portion information acquisition unit 25 acquires tool information from a tool information storage unit 15 included in the NC device 11, which stores the tool information. In the invention, the tool information refers to various types of information including dimensions of the tool 6, such as a diameter DT, a total length, a blade length and the number of blades, a protruding length LT of the holder 5, and a material of the tool 6, in addition to the name of the tool 6.

[0023] The vibration characteristic estimation system 21 further includes a compensation factor storage unit 26, a compensation factor acquisition unit 27, and a second vibration characteristic estimation unit 28. The compensation factor storage unit 26 stores a compensation factor C indicating the relationship between the first vibration characteristic and a second vibration characteristic in association with the machine information, the gripper tool information, and the tool information. The ratio, namely, a compliance, of the magnitude of vibration at the tip of the tool 6 to the excitation force applied to the tip of the tool 6 performing machining is the second vibration characteristic in the embodiment.

[0024] The compensation factor obtaining unit 27 obtains the compensation factor C from the compensation factor storage unit 26. The second vibration characteristic estimating unit 28 estimates the second vibration characteristic by compensating the first vibration characteristic using the compensation factor C.

[0025] The following describes an estimation method of the second vibration characteristic by the vibration characteristic estimation system of the invention.

[0026] Fig. Figure 2 is a flowchart illustrating the estimation method of the second vibration characteristic.

[0027] As a first vibration characteristic acquisition step S1, the first vibration characteristic acquisition unit 22 first acquires a first vibration characteristic. For acquiring the first vibration characteristic, a known method that can calculate the ratio of the amount of vibration of the main spindle housing 3 to the excitation force applied to the tip of the tool 6 performing machining can be arbitrarily selected. In the embodiment, it is assumed that the first vibration characteristic is acquired by analyzing the output information of the acceleration sensor 9 during machining by a vibration analysis unit 12 included in the NC device 11, with reference to the method disclosed in JP 2020-80015 A.

[0028] Next, as a machine information acquiring step S2, the machine information acquiring unit 23 acquires machine information from the machine information storage unit 13.

[0029] Subsequently, as a gripping tool information acquiring step S3, the gripping tool information acquiring unit 24 acquires gripping tool information from the gripping tool information storing unit 14.

[0030] Continuously, as a machined section information acquiring step S4, the machined section information acquiring unit 25 acquires the tool information from the tool information storage unit 15.

[0031] As a compensation factor obtaining step S5, the compensation factor obtaining unit 27 obtains a compensation factor C based on the machine information, gripping tool information, and tool information obtained in the machine information obtaining step S2, the gripping tool information obtaining step S3, and the machined portion information obtaining step S4 from the compensation factor storage unit 26.

[0032] Then, as a second vibration characteristic estimation step S6, the second vibration characteristic estimation unit 28 estimates a second vibration characteristic by compensating the first vibration characteristic obtained by the first vibration characteristic obtaining unit 22 using the compensation factor C obtained by the compensation factor obtaining unit 27 at a target point where a vibration characteristic is desired.

[0033] Here, the details of the compensation factor C used in the vibration characteristic estimation system of the invention will be described based on examples.

[0034] Fig. 3 is a diagram showing an example of measurement of the first vibration characteristic and the second vibration characteristic. Fig. Figure 4 is a diagram showing an example of a compensation factor.

[0035] As an example, the first vibration characteristic and the second vibration characteristic obtained by an impact test in a state where a cemented carbide end mill, namely the tool 6 having a DT = 20 mm, is mounted on the holder 5 having a LT = 60 mm in the machining center m having the configuration described above are shown in Fig. 3. The impact test is performed using a hammer with a built-in load sensor having an acceleration sensor (not shown) attached to the tip of the cemented carbide end mill on the machining center m. In the impact test, the tip of the cemented carbide end mill is excited with the hammer to obtain the output of the load sensor built into the hammer, the output of the acceleration sensor 9 attached to the main spindle housing 3, and the output of the acceleration sensor attached to the tip of the cemented carbide end mill at the time of excitation. Of the respective obtained outputs, the ratio of the output of the acceleration sensor 9 to the hammer output is calculated as the first vibration characteristic, and the ratio of the output of the acceleration sensor attached to the tip of the cemented carbide end mill to the hammer output is calculated as the second vibration characteristic.When estimating the second vibration characteristic from the first vibration characteristic, the vibration characteristic estimation system 21 preferably obtains the first vibration characteristic by analyzing the vibration during machining, so that the estimation can be performed even if an operator does not have specialized techniques or knowledge of vibration. However, the first vibration characteristic for calculating the compensation factor C can be obtained by a person skilled in the art who performs an impact test on an occasion different from the estimation of the second vibration characteristic, such as before delivery of the machining center m.

[0036] Comparing the first vibration characteristic and the second vibration characteristic obtained by the impact test, it can be seen that the second vibration characteristic is much larger. This is because both the first vibration characteristic and the second vibration characteristic show a decay of vibration, and the tip of the carbide end mill vibrates more easily than the main spindle housing 3.

[0037] In addition, when the compensation factor C, which is the ratio between the first vibration characteristic and the second vibration characteristic, is calculated and recorded, it can be seen that the compensation factor C, as shown in Fig. 4 changes with a frequency f. The reason why the compensation factor C changes with the frequency f is that a vibration mode, that is, the vibration state, changes due to a complex system in which the holder 5 and the main spindle 4 intervene between the tip of the tool 6, which is an estimation target point of the vibration characteristic, and the acceleration sensor 9. The change in the vibration mode causes a difference in how a vibration propagates from the tool 6 to the main spindle housing 3. In other words, it can be said that when the frequency f, a mechanical structure of the machining center m, the holder 5, and the tool 6 are each the same, the way a vibration propagates from the tool 6 to the main spindle housing 3 is the same.

[0038] That is, as long as the frequency f is clear, the second vibration characteristic can be estimated using the compensation factor C from the first vibration characteristic. Here, in the embodiment, the frequency f of vibration in the main spindle housing 3 can be measured by the acceleration sensor 9. Accordingly, as long as the first vibration characteristic of the system including the main spindle housing 3 and the compensation factor C can be obtained for an estimation target point, the second vibration characteristic at the estimation target point can be estimated from the first vibration characteristic.

[0039] On the other hand, as described above, the first vibration characteristic is acquired by the first vibration characteristic acquisition unit 22. In addition, the vibration characteristic estimation system 21 stores the compensation factor C in association with the machine information, the gripping tool information, and the tool information in the compensation factor storage unit 26.

[0040] However, when estimating the second vibration characteristic using the compensation factor C from the first vibration characteristic, the mechanical structure of the machining center m, the holder 5, and the tool 6 must each be the same as described above. That is, in order to estimate the second vibration characteristic using the compensation factor C from the first vibration characteristic, it is first necessary to obtain a compensation factor C for each of the desired machine information, gripper tool information, and tool information, and then store comprehensive compensation factors C in the compensation factor storage unit 26.

[0041] As an alternative to acquiring and storing large-scale compensation factors C as described above, the applicant has found that the compensation factor C, as shown in Formula 1, can be expressed as the product of a compensation factor T and a compensation factor M. In the embodiment, the compensation factor M is a compensation factor C when the tool 6, which is a reference tool used as a reference for compensation, is attached to the holder 5, and is obtained for each combination of the mechanical structure of the machining center m with the holder 5. The compensation factor T is a ratio between the compensation factor C of the reference tool and a compensation factor C of the tool 6, which is a target tool as an estimation object. C(f)=T×M(f)

[0042] Since the compensation factor T is a value that depends on the shape of the tool 6, it is linked to the tool information as a constant that does not depend on frequency. For example, for the tool 6 with a DT of 12 mm, 16 mm, or 20 mm mounted on the holder 5 of the machining center m under the condition of an LT of 60 mm, 70 mm, or 80 mm, the compensation factor T calculated from the compensation factor C obtained from a direct measurement of the impact test is shown in Table 1. Here, the tool 6 with an LT of 60 mm and a DT of 20 mm is selected as the reference tool. As described above, the compensation factor M for the tool 6, which is the reference tool, is equal to the compensation factor C.Therefore, for example, the compensation factor T of tool 6 with LT = 60 mm and DT = 12 mm is calculated by dividing the compensation factor C of tool 6 by the compensation factor M for each frequency and the average value is obtained.

[0043] The compensation factor M is a value obtained for a plurality of systems including the holder 5, the main spindle 4, and the main spindle housing 3. Therefore, the compensation factor M is associated with the machine information, the gripping tool information, and information of the reference tool as a function of the frequency f.

[0044] Thus, by selecting the compensation factor C as a function of the frequency f, even for the tool 6 for which a compensation factor C has not been obtained, based on the obtained compensation factor C and Formula 1, the compensation factor C can be calculated from the interpolation or extrapolation of the compensation factor T using an approximate formula. Therefore, even if all the compensation factors C are not always stored in the compensation factor storage unit 26, a compensation factor C is calculated and stored in the compensation factor storage unit 26 based on the acquired frequency, machine information, gripping tool information, and tool information, and used in S5 and S6.Accordingly, even if a compensation factor C has not been obtained for an estimation target point of a vibration characteristic, the vibration characteristic at the target point, that is, the second vibration characteristic, can be estimated using an obtained compensation factor C. LT / DT 12 mm 16 mm 20 mm 60 mm 4,7 1,8 1,0 70 mm 5,6 2,2 1,3 80 mm 7,5 2,8 1,6

[0045] Fig. 5 and Fig. 6 are comparisons between the result of a direct measurement and the estimation result of the second vibration characteristic.

[0046] The accuracy of the based on the flow chart in Fig. The second vibration characteristic estimated in Figure 2 is examined below. Specifically, the case where the compensation factor C for the tip of tool 6, as the target point for estimating the vibration characteristic, was not obtained was examined.

[0047] The estimation accuracy was investigated by comparing the direct measurement result with the estimation result when the tool 6 was mounted on the holder 5 under the conditions of DT = 16 mm and LT = 64 mm. The conditions of DT = 16 mm and LT = 64 mm fall within the range shown in Table 1, namely, the range of the conditions of 60 mm ≤ LT ≤ 80 mm and 12 mm ≤ DT ≤ 20 mm. Therefore, an approximate formula for a compensation factor T for LT was obtained from the compensation factors T obtained for tool 6 with an LT of 60 mm, 70 mm, and 80 mm under the condition of a DT of 16 mm, and the compensation factor C was obtained from the interpolation of the compensation factor T using the approximate formula to estimate the second vibration characteristic by compensating the directly measured first vibration characteristic. As a result, as shown in Fig. 5, the second vibration characteristic can be estimated with a high accuracy from the first vibration characteristic.

[0048] In addition, by comparing the direct measurement result with the estimation result, the estimation accuracy was investigated when the tool 6 was mounted on the holder 5 under the conditions of DT = 20 mm and LT = 100 mm. The conditions of DT = 20 mm and LT = 100 mm do not fall within the range shown in Table 1, namely, within the range of the conditions of 60 mm ≤ LT ≤ 80 mm and 12 mm ≤ DT ≤ 20 mm. Therefore, an approximate formula for a compensation factor T for a LT was obtained from the compensation factors T obtained for the tool 6 with an LT of 60 mm, 70 mm, and 80 mm under the condition of a DT of 20 mm, and the compensation factor C was obtained from the extrapolation of the compensation factor T using the approximate formula to estimate the second vibration characteristic by compensating the directly measured first vibration characteristic. As a result, as shown in Fig.6, the second vibration characteristic can be estimated with a high accuracy from the first vibration characteristic.

[0049] In addition, using a case where the tool 6 is attached to the holder 5 under the conditions of DT = 18 mm and LT = 75 mm as an example, a method for obtaining the compensation factor C will be described for the tool 6 under the conditions of both DT and LT not listed in Table 1. First, an approximate formula for a compensation factor T for DT is obtained from the compensation factors T obtained for the tool 6 with a DT of 12 mm, 16 mm, and 20 mm under the condition of an LT of 60 mm, and a compensation factor T under the conditions of LT = 60 mm and DT = 18 mm is obtained using the approximate formula. Similarly, compensation factors T are obtained under the conditions of LT = 70 mm and DT = 18 mm and the conditions of LT = 80 mm and DT = 18 mm.Next, an approximate formula for a compensation factor T for an LT is obtained from the compensation factors T obtained for the tool 6 with an LT of 60 mm, 70 mm and 80 mm under the condition of a DT of 18 mm, and the compensation factor C is obtained from the interpolation of the compensation factor C using the approximate formula.

[0050] The vibration characteristic estimation system 21 having the above-described configuration includes the first vibration characteristic acquiring unit 22, the machine information acquiring unit 23, the gripping tool information acquiring unit 24, the machined portion information acquiring unit 25, the compensation factor storage unit 26, the compensation factor acquiring unit 27, and the second vibration characteristic estimation unit 28 in the machining center m that performs machining by relatively moving the tool 6 and the workpiece 8.The first vibration characteristic acquisition unit 22 acquires a first vibration characteristic based on an output of the acceleration sensor 9 mounted on the main spindle housing 3 of the machining center m when an excitation force is applied to the tip of the tool 6, which is a machining point as a contact point between the tool 6 and the workpiece 8 during machining. The machine information acquisition unit 23 acquires machine information including a name, axis configuration, and component information of the machining center m, and attachment position information of the acceleration sensor 9. The gripping tool information acquisition unit 24 acquires gripping tool information including a name, dimension, and material of the holder 5 that grips the tool 6, and a gripping method of the tool 6.The machined-portion information acquisition unit 25 acquires tool information including a name, a dimension, and a material of the tool 6. The compensation factor storage unit 26 stores the compensation factor C, which represents a relationship between the first vibration characteristic and a second vibration characteristic, in association with the machine information, the gripping tool information, and the tool information. The second vibration characteristic is based on an amount of vibration at the tip of the tool 6 when an excitation force is applied to the tip of the tool 6. The compensation factor acquisition unit 27 acquires the compensation factor C based on the machine information, the gripping tool information, and the tool information from the compensation factor storage unit 26.The second vibration characteristic estimation unit 28 estimates the second vibration characteristic by compensating the first vibration characteristic obtained by the first vibration characteristic obtaining unit 22 using the compensation factor C obtained by the compensation factor obtaining unit 27. The compensation factor C is configured based on the machine information and a frequency associated with the machine information, and the frequency is obtained from the main spindle housing 3.

[0051] Accordingly, in the machining center m, the second vibration characteristic, which is a vibration characteristic at the tip of the tool 6 where the acceleration sensor 9 is difficult to mount, can be estimated with high accuracy by compensating the first vibration characteristic, which is a vibration characteristic of the main spindle housing 3, which is a point where the acceleration sensor 9 is easily mountable, based on the machine information, the gripping tool information, and the tool information.

[0052] In addition, the compensation factor C, which has the configuration described above, contains a constant associated with the tool information and is a frequency function associated with the machine information.

[0053] Accordingly, even if a compensation factor C for the tip of the tool 6, which is an estimation target point of a vibration characteristic, has not been obtained, the second vibration characteristic, which is the vibration characteristic at the tip of the tool 6, can be estimated using an obtained compensation factor C.

[0054] While the invention is described based on an example presented above, the technical scope of the invention is not limited thereto. The configuration related to the vibration characteristic estimation system in a machine tool, the machine tool, and the vibration characteristic estimation method of the invention is not limited to the aspect described in the above embodiment and can be appropriately changed as necessary without departing from the spirit of the invention.

[0055] For example, the first vibration characteristic and the second vibration characteristic are not limited to compliance, but can be different values, such as mobility or inertance. Furthermore, as long as a calculation is possible by compensating the first vibration characteristic with a compensation factor, the first vibration characteristic and the second vibration characteristic can be a combination of values ​​of a different type.

[0056] Furthermore, the sensor that serves as an output source used to obtain the first vibration characteristic is not limited to an acceleration sensor and can be implemented, for example, as encoders included in a main spindle motor, an X-axis motor, a Y-axis motor, and a Z-axis motor. In this case, the compensation factor M is obtained for components up to the mounting positions of the encoders.

[0057] In the embodiment, while the machine information acquisition unit acquires the machine information from an NC device, the machine information acquisition unit may acquire the machine information from a device other than the NC device, such as an external information device, or may directly input the machine information through, for example, a separately arranged input unit. The same applies to the gripping tool information acquisition unit and the machined portion information acquisition unit.

[0058] Furthermore, the components included in the compensation factor T and the compensation factor M are not limited to the combinations of the tool information, the machine information, and the gripping tool information. For example, the compensation factor M may be set to a compensation factor C when the combination of the tool 6 as a reference tool with the holder 5 is mounted on the main spindle 4; the compensation factor T may be selected as a ratio between the compensation factor C of the reference tool holder and a compensation factor C of the combination of the tool 6 as an estimation object and the holder 5; and the gripping tool information may also be linked to the compensation factor T.In the same way as in the embodiment, by approximating the compensation factor T by the size of the tool 6 with DT and LT and the size of the holder 5 with DH and LH, an estimation for the size of the holder 5 with DH' and LH' for which the compensation factor C has not been obtained becomes possible.

[0059] Furthermore, in the embodiment, the estimation target point of one vibration characteristic is set to a tool tip, and the second vibration characteristic is set to the compliance of the tool tip. However, estimation can be performed by setting the estimation target point of the vibration characteristic to a workpiece and setting the second vibration characteristic to the compliance of the workpiece. In this case, the acceleration sensor 9 is mounted on the workpiece table 7 to which the workpiece 8 is mounted, and the frequency is obtained from the workpiece table 7.Then, in S3, the gripping tool information acquisition unit 24 acquires workpiece gripping tool information including a workpiece gripping tool name, a workpiece gripping tool dimension, a workpiece gripping method such as a position, a gripping force, and a gripping direction, and a workpiece gripping tool material from the gripping tool information storage unit 14. In S4, the machined portion information acquisition unit 25 acquires workpiece information including a workpiece name, a workpiece dimension, and a workpiece material from a workpiece information storage unit included in the NC device 11 that stores the workpiece information. Further, in S5, the compensation factor acquisition unit 27 acquires the compensation factor C from the compensation factor storage unit 26 based on at least one of the machine information, the workpiece gripping tool information, and the workpiece information.

[0060] Additionally, the object to which the invention is adapted is not limited to a machining center, as long as it is a machine tool that performs machining by relatively moving a tool and a workpiece. For example, the invention may be adapted to a multitasking machine, and in this case, the acceleration sensor may be mounted on a main spindle housing of a workpiece main spindle that rotates the workpiece to estimate the compliance of the workpiece. Furthermore, the invention may also be adapted to a lathe, and in this case, the acceleration sensor may be mounted on a tool holder to which a non-rotating tool is attached to estimate the compliance of the tool. In this case, the frequency is obtained from the tool holder.

[0061] Here, when the invention is applied to the multi-tasking machine and the lathe, the first vibration characteristic and the second vibration characteristic are selected as one compliance. However, as described above, the first vibration characteristic and the second vibration characteristic are not limited to one compliance.

[0062] It is explicitly stated that all features disclosed in the description and / or the claims are intended to be disclosed separately and independently of one another for the purpose of original disclosure as well as for the purpose of limiting the claimed invention, regardless of the arrangement of features in the embodiments and / or the claims. It is explicitly stated that all ranges of values ​​or indications of groups of units disclose every possible intermediate value or intermediate unit for the purpose of original disclosure as well as for the purpose of limiting the claimed invention, in particular as limits of ranges of values. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2020

[0002] JP 80015 A

[0002] JP 2012-187691 A [0003, 0004] JP 2020-80015 A [0019, 0027]

Claims

[1] Vibration characteristic estimation system (21) in a machine tool (m) for machining by relative movement of a tool (6) and a workpiece (8), comprising: a first vibration characteristic obtaining unit (22) that obtains a first vibration characteristic based on an output of a sensor (9) attached to the machine tool (m) when an excitation force is applied to a machining point as a contact point between the tool (6) and the workpiece (8) during machining; a machine information acquiring unit (23) that acquires machine information including at least one of a name, an axis configuration, and component information of the machine tool (m), and mounting position information of the sensor (9); a gripping tool information acquiring unit (24) that acquires gripping tool information including at least one of a name, a dimension, and a material of a gripping tool (5) that grips the tool (6) or the workpiece (8), and a gripping method of the tool (6) of the workpiece (8); a machined portion information acquisition unit (25) that acquires at least one of tool information and workpiece information, wherein the tool information includes at least one of a name, a dimension, and a material of the tool (6), and the workpiece information includes at least one of a name, a dimension, and a material of the workpiece (8); a compensation factor storage unit (26) that stores a compensation factor representing a relationship between the first vibration characteristic and a second vibration characteristic in association with at least one of the machine information, the gripping tool information, the tool information, and the workpiece information, wherein the second vibration characteristic is based on an amount of vibration at the machining point when an excitation force is applied to the machining point; a compensation factor obtaining unit (27) that obtains the compensation factor based on at least one of the machine information, the gripping tool information, the tool information, and the workpiece information from the compensation factor storage unit (26); and a second vibration characteristic estimation unit (28) that estimates the second vibration characteristic by compensating the first vibration characteristic obtained by the first vibration characteristic obtaining unit (22) using the compensation factor obtained by the compensation factor obtaining unit (27), wherein the compensation factor is designed as a function based on the machine information and a frequency associated with the machine information, and the frequency is obtained from the sensor (9). [2] Vibration characteristic estimation system (21) in a machine tool (m) according to claim 1, wherein the compensation factor includes a constant associated with at least the tool information. [3] Vibration characteristic estimation system (21) in a machine tool (m) according to claim 1, wherein the compensation factor is a frequency function associated with at least the machine information. [4] A machine tool (m) comprising the vibration characteristic estimation system (21) according to any one of claims 1 to 3. [5] Vibration characteristic estimation method in a machine tool (m) for machining by a relative movement of a tool (6) and a workpiece (8), comprising: a first vibration characteristic obtaining step for obtaining a first vibration characteristic based on an output of a sensor (9) attached to the machine tool (m) when an excitation force is applied to a machining point of the tool (6) or the workpiece (8) as a contact point between the tool (6) and the workpiece (8) during machining; a machine information acquiring step for acquiring machine information including at least one of a name, an axis configuration, and component information of the machine tool (m), and mounting position information of the sensor (9); a gripping tool information acquiring step of acquiring gripping tool information including at least one of a name, a dimension, and a material of a gripping tool (5) that grips the tool (6) or the workpiece (8), and a gripping method of the tool (6) or the workpiece (8); a machined portion information obtaining step of obtaining at least one of tool information and workpiece information, wherein the tool information includes at least one of a name, a dimension, and a material of the tool (6), and the workpiece information includes at least one of a name, a dimension, and a material of the workpiece (8); a compensation factor obtaining step for obtaining a compensation factor representing a relationship between the first vibration characteristic and a second vibration characteristic based on at least one of the machine information, the gripping tool information, the tool information, and the workpiece information, wherein the second vibration characteristic is based on an amount of vibration at the machining point when the excitation force is applied to the machining point; and a second vibration characteristic estimation step for estimating the second vibration characteristic by compensating the first vibration characteristic obtained in the first vibration characteristic obtaining step using the compensation factor obtained in the compensation factor obtaining step, wherein the compensation factor is configured based on the machine information and a frequency associated with the machine information, and the frequency is obtained from the sensor (9).

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