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CN-113843658-B - Precision diagnostic device and precision diagnostic method for machine tool

CN113843658BCN 113843658 BCN113843658 BCN 113843658BCN-113843658-B

Abstract

Provided is a precision diagnostic device and a precision diagnostic method for a machine tool. The change in accuracy due to thermal displacement can be diagnosed, and the appropriate timing for measuring the displacement correction can be instructed for the correction value of the coordinate of the machine tool. The accuracy diagnosis device (7) is provided with a temperature reference value recording unit (103) for recording a temperature reference value (104) of a 5-axis machining center (1), wherein the 5-axis machining center (1) is provided with a body temperature sensor (4) and an air temperature sensor (5) for measuring a temperature that changes according to a use environment and an operation, acquires temperature data (101) measured by the body temperature sensor (4) and the air temperature sensor (5), and diagnoses a change in accuracy of the 5-axis machining center (1) based on a first change index (a first temperature index (106)) derived from a magnitude of a change in temperature per a predetermined time and a second change index (a second temperature index (107)) derived from a current temperature and the temperature reference value (104).

Inventors

  • Mizoguchi Uji

Assignees

  • 大隈株式会社

Dates

Publication Date
20260508
Application Date
20210624
Priority Date
20200625

Claims (11)

  1. 1. A precision diagnostic device for a machine tool, which diagnoses the precision of the machine tool, the machine tool having a change amount detection unit for measuring a change amount that changes according to an installation environment and an operation, characterized in that, The accuracy diagnosis device of the machine tool comprises a variation reference value recording part for recording the reference value of the variation, In the precision diagnostic device of the machine tool, The variation measured by the variation detecting unit is acquired, Diagnosing a change in the accuracy of the machine tool based on a first change index derived from the magnitude of the change in the change amount per predetermined time and a second change index derived from the current change amount and the reference value, The change amount reference value recording unit records and updates the reference value at a time interval longer than the predetermined time when the first change index is derived, The precision diagnostic device for a machine tool further includes a precision diagnostic unit that diagnoses a change in the precision from the first change index and derives a first diagnostic result, diagnoses a change in the precision from the second change index and derives a second diagnostic result, and a precision countermeasure judging unit that judges a precision countermeasure for ensuring the precision of the machine tool from a combination of the first diagnostic result and the second diagnostic result, The accuracy countermeasure judging unit indicates the first diagnosis result and the second diagnosis result with good or bad, If the first diagnosis result is bad, it is determined that machining and on-machine measurement in the machine tool are not started or stopped until the machine tool is again good, When the first diagnosis result is good and the second diagnosis result is bad, it is determined that the correction value of the coordinate of the machine tool is reset before starting or continuing the machining and the on-machine measurement in the machine tool.
  2. 2. A precision diagnostic device for a machine tool, which diagnoses the precision of the machine tool, the machine tool having a change amount detection unit for measuring a change amount that changes according to an installation environment and an operation, characterized in that, The accuracy diagnosis device of the machine tool comprises a variation reference value recording part for recording the reference value of the variation, In the precision diagnostic device of the machine tool, The variation measured by the variation detecting unit is acquired, Diagnosing a change in the accuracy of the machine tool based on a first change index derived from the magnitude of the change in the change amount per predetermined time and a second change index derived from the current change amount and the reference value, The change amount reference value recording unit records and updates the reference value at a time interval longer than the predetermined time when the first change index is derived, The precision diagnostic device for a machine tool further includes a precision diagnostic unit that diagnoses a change in the precision from the first change index and derives a first diagnostic result, diagnoses a change in the precision from the second change index and derives a second diagnostic result, and a precision countermeasure judging unit that judges a precision countermeasure for ensuring the precision of the machine tool from a combination of the first diagnostic result and the second diagnostic result, The accuracy countermeasure judging unit indicates the first diagnosis result and the second diagnosis result with good or bad, If any one of the first diagnosis result and the second diagnosis result is poor, it is determined that the correction value of the coordinate of the machine tool is reset.
  3. 3. A precision diagnostic device for a machine tool, which diagnoses the precision of the machine tool, the machine tool having a change amount detection unit for measuring a change amount that changes according to an installation environment and an operation, characterized in that, The accuracy diagnosis device of the machine tool comprises a variation reference value recording part for recording the reference value of the variation, In the precision diagnostic device of the machine tool, The variation measured by the variation detecting unit is acquired, Diagnosing a change in the accuracy of the machine tool based on a first change index derived from the magnitude of the change in the change amount per predetermined time and a second change index derived from the current change amount and the reference value, The change amount reference value recording unit records and updates the reference value at a time interval longer than the predetermined time when the first change index is derived, The precision diagnostic device for a machine tool further includes a precision diagnostic unit that diagnoses a change in the precision from the first change index and derives a first diagnostic result, diagnoses a change in the precision from the second change index and derives a second diagnostic result, and a precision countermeasure judging unit that judges a precision countermeasure for ensuring the precision of the machine tool from a combination of the first diagnostic result and the second diagnostic result, The accuracy countermeasure judging unit indicates the first diagnosis result and the second diagnosis result with good or bad, When the second diagnosis result is poor and the first diagnosis result is good, it is determined that the measurement is appropriate for correcting the accuracy of the machine tool.
  4. 4. The precision diagnostic apparatus for a machine tool according to any one of claims 1 to 3, wherein, The accuracy diagnosis device for a machine tool includes an accuracy score calculation unit that calculates a first accuracy score obtained by digitizing the magnitude of the influence of the change amount on the accuracy of the machine tool based on the first change index, and a second accuracy score obtained by digitizing the magnitude of the influence of the change amount on the accuracy of the machine tool based on the second change index.
  5. 5. The apparatus for diagnosing precision of a machine tool according to claim 4, wherein, The accuracy diagnosis unit derives the first diagnosis result from the first accuracy score and derives the second diagnosis result from the second accuracy score based on a predetermined threshold.
  6. 6. The precision diagnostic apparatus for a machine tool according to any one of claims 1 to 3, wherein, The precision diagnostic device for a machine tool is provided with a diagnostic result notification means that notifies the first diagnostic result and the second diagnostic result.
  7. 7. The precision diagnostic apparatus for a machine tool according to any one of claims 1 to 3, wherein, The accuracy diagnosis device for a machine tool includes an accuracy countermeasure execution unit that executes or suspends a program for performing machining or on-machine measurement in the machine tool in accordance with the accuracy countermeasure determined by the accuracy countermeasure determination means.
  8. 8. A precision diagnostic apparatus of a machine tool according to any one of claims 1 to 3, wherein the variation amount is temperature.
  9. 9. A method for diagnosing the accuracy of a machine tool provided with a change amount detection unit for measuring a change amount that changes according to an installation environment and an operation, characterized in that, In the method for diagnosing the accuracy of the machine tool, The change amount is acquired from the change amount detection unit, Diagnosing a change in the accuracy of the machine tool based on a first change index derived from the magnitude of the change in the change amount per a predetermined time with respect to a preset reference value and a second change index derived from the difference between the current change amount and the reference value, determining an accuracy countermeasure for securing the accuracy of the machine tool based on a combination of the first diagnosis result and the second diagnosis result, Recording and updating the reference value at time intervals longer than the predetermined time when the first change index is derived, The first diagnosis result and the second diagnosis result are represented with good or bad, If the first diagnosis result is bad, it is determined that machining and on-machine measurement in the machine tool are not started or stopped until the machine tool is again good, When the first diagnosis result is good and the second diagnosis result is bad, it is determined that the correction value of the coordinate of the machine tool is reset before starting or continuing the machining and the on-machine measurement in the machine tool.
  10. 10. A method for diagnosing the accuracy of a machine tool provided with a change amount detection unit for measuring a change amount that changes according to an installation environment and an operation, characterized in that, In the method for diagnosing the accuracy of the machine tool, The change amount is acquired from the change amount detection unit, Diagnosing a change in the accuracy of the machine tool based on a first change index derived from the magnitude of the change in the change amount per a predetermined time with respect to a preset reference value and a second change index derived from the difference between the current change amount and the reference value, determining an accuracy countermeasure for securing the accuracy of the machine tool based on a combination of the first diagnosis result and the second diagnosis result, Recording and updating the reference value at time intervals longer than the predetermined time when the first change index is derived, The first diagnosis result and the second diagnosis result are represented with good or bad, If any one of the first diagnosis result and the second diagnosis result is poor, it is determined that the correction value of the coordinate of the machine tool is reset.
  11. 11. A method for diagnosing the accuracy of a machine tool provided with a change amount detection unit for measuring a change amount that changes according to an installation environment and an operation, characterized in that, In the method for diagnosing the accuracy of the machine tool, The change amount is acquired from the change amount detection unit, Diagnosing a change in the accuracy of the machine tool based on a first change index derived from the magnitude of the change in the change amount per a predetermined time with respect to a preset reference value and a second change index derived from the difference between the current change amount and the reference value, determining an accuracy countermeasure for securing the accuracy of the machine tool based on a combination of the first diagnosis result and the second diagnosis result, Recording and updating the reference value at time intervals longer than the predetermined time when the first change index is derived, The first diagnosis result and the second diagnosis result are represented with good or bad, When the second diagnosis result is poor and the first diagnosis result is good, it is determined that the measurement is appropriate for correcting the accuracy of the machine tool.

Description

Precision diagnostic device and precision diagnostic method for machine tool Technical Field The present invention relates to a precision diagnostic device and a precision diagnostic method for a machine tool, which diagnose the influence of the environment in which the machine tool is located and the operation on the precision of the machine tool. Background When a workpiece is machined by using a machine tool, various parts of the machine tool are thermally deformed due to temperature changes in the installation environment of the machine tool and heat generated during operation. As a result, there are cases where the relative positions of the spindle and the workpiece change, that is, thermal displacement occurs in the machine tool, and the accuracy of machining the workpiece may be deteriorated. As a method for suppressing the thermal displacement of the machine tool, for example, thermal displacement correction is widely used in which a temperature sensor is attached to each part of a structure (hereinafter, also referred to as a machine body) of the machine tool, the amount of thermal displacement of the machine tool is calculated based on the measured temperature, and the amount of shaft movement is changed according to the calculated amount of thermal displacement. However, there is a limit to the accuracy of the thermal displacement correction, and when the temperature change is large, an error occurs. As a countermeasure for the case where the temperature change is large, patent document 1 discloses a method in which an error in thermal displacement correction becomes large particularly when a rapid temperature change occurs, and therefore, the degree of influence on the workpiece machining accuracy change of the machine tool is calculated from the speed of the temperature change of the machine body, and the state of the machine tool is diagnosed based on the calculated degree of influence. In addition, when the device is used for a long period of time, there are cases where the temperature of the body gradually changes and the temperature greatly changes before the start of use, and thus the error in thermal displacement correction becomes large. As a known countermeasure method in this case, there is known a method of measuring a correction value of the coordinate of the machine tool, for example, a workpiece origin offset value, a tool length offset value, or the like again, and updating these values to cancel an error and maintain accuracy. Patent document 2 discloses a method of dividing a rotary table and measuring the position of a tool to be measured on the table at a plurality of angles to determine and correct a geometric error and a scale error, thereby maintaining the accuracy of the machine tool. Patent document 1 Japanese patent application laid-open No. 2019-136846 Patent document 2 Japanese patent No. 6295070 The method disclosed in patent document 1 can detect that a rapid temperature change has occurred, and it can be said that it is effective to determine whether or not to start processing and measurement that end in a relatively short period of time of about several minutes to 1 hour, with respect to the installation environment of the machine tool. However, it is difficult to cope with a situation where the temperature gradually changes over a long period of time, and the displacement becomes large. On the other hand, it can be said that the above known countermeasure method and the method disclosed in patent document 2 are useful in a situation where the temperature gradually changes over time and the displacement becomes large. However, since the operator needs to determine based on experience when to perform the measurement for the displacement correction, the measurement cannot be performed at the time when the measurement is required, or the measurement is performed with an excessive frequency. Therefore, there is a possibility that the productivity may be lowered. Further, since the method described in patent document 2 is to measure the position of the measuring tool on the rotary table at a plurality of angles, it takes a long time to measure, and therefore, if the measurement is performed under a condition in which the temperature is suddenly changed, thermal displacement occurs during the measurement, and there is a possibility that the measurement accuracy is deteriorated. Disclosure of Invention Accordingly, an object of the present invention is to provide a precision diagnostic device and a precision diagnostic method for a machine tool, which can diagnose a precision change due to thermal displacement, and can instruct a correct timing for measuring a displacement correction to a correction value of coordinates of the machine tool such as a workpiece origin offset value and a tool length offset value, regardless of a rapid temperature change or a gradual temperature change. In order to achieve the above object, the invention according to claim 1 is an accuracy di