Precision diagnosis device and precision diagnosis method for machine tool

Abstract

Provided are a precision diagnosis device and a precision diagnosis method for a machine tool. Precision changes caused by thermal displacement can be diagnosed, and the appropriate timing for displacement correction can be indicated for correction values of coordinates of the machine tool, etc. A precision diagnosis device (7) includes a temperature reference value recording unit (103) that records a temperature reference value (104) of a 5-axis machining center (1), the 5-axis machining center (1) has a body temperature sensor (4) that measures a temperature that changes according to a use environment and a running operation, and an air temperature sensor (5), acquires temperature data (101) measured by the body temperature sensor (4) and the air temperature sensor (5), diagnoses changes in precision 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 for each predetermined time and a second change index (a second temperature index (107)) derived from a current temperature and the temperature reference value (104).

Description

Technical Field

[0001] This invention relates to a machine tool accuracy diagnosis device and method for diagnosing the influence of the machine tool's environment and operating actions on the machine tool's accuracy. Background Technology

[0002] When machining workpieces using machine tools, thermal deformation occurs in various parts of the machine tool due to temperature variations in the machine tool's operating environment and heat generated during operation. As a result, the relative position of the spindle and workpiece may change, i.e., thermal displacement occurs within the machine tool, which can sometimes degrade the accuracy of workpiece machining. One widely used method to suppress thermal displacement is thermal displacement correction, which involves installing temperature sensors in various parts of the machine tool's structure (hereinafter referred to as the machine body), calculating the amount of thermal displacement based on the measured temperature, and then adjusting the axis movement accordingly. However, the accuracy of thermal displacement correction has limitations, and errors can occur under conditions of large temperature variations.

[0003] As a countermeasure for situations with large temperature changes, Patent Document 1 discloses the following method: Since the error of thermal displacement correction becomes larger, especially when there is a rapid temperature change, the influence of the temperature change rate of the machine body on the change of workpiece machining accuracy of the machine tool is calculated, and the condition of the machine tool is diagnosed based on the calculated influence.

[0004] Furthermore, under prolonged use, the machine body temperature gradually changes, resulting in a significant temperature change compared to before use, thus increasing the error in thermal displacement correction. A known countermeasure for this situation is to re-measure and update the machine tool's coordinate correction values, such as workpiece origin offset and tool length offset, thereby eliminating errors and maintaining accuracy. Additionally, Patent Document 2 discloses a method that determines and corrects geometric errors and scaling errors by indexing a rotary table and measuring the position of the tool on the table from multiple angles, thereby maintaining the machine tool's accuracy.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-136846

[0006] Patent Document 2: Japanese Patent No. 6295070

[0007] The method disclosed in Patent Document 1 can detect rapid temperature changes, and can be considered effective in determining the quality of the machine tool's setup environment and in judging whether to start processing and measuring within a relatively short period of a few minutes to an hour. However, it is difficult to handle situations where the temperature gradually changes over a long period of time, resulting in greater displacement.

[0008] On the other hand, it can be said that the aforementioned known countermeasures and the method disclosed in Patent Document 2 are useful in situations where the displacement increases due to gradual temperature changes over a long period. However, the operator needs to make judgments based on experience regarding when to perform the displacement correction measurement, thus making it impossible to perform the measurement at the necessary time or resulting in excessively frequent measurements. Therefore, problems such as decreased productivity may occur. Furthermore, the method described in Patent Document 2 measures the position of the tool being measured on the rotating worktable from multiple angles, which is time-consuming. Therefore, if the measurement is performed under conditions of rapid temperature changes, thermal displacement may occur during the measurement, potentially degrading the measurement accuracy. Summary of the Invention

[0009] Therefore, the purpose of this invention is to provide a machine tool accuracy diagnostic device and accuracy diagnostic method that can diagnose accuracy changes caused by thermal displacement, whether the temperature changes rapidly or gradually, and can indicate the appropriate time to perform displacement correction measurements based on the machine tool coordinate correction values ​​such as workpiece origin offset and tool length offset.

[0010] To achieve the above objectives, the invention of technical solution 1 is a precision diagnostic device for diagnosing the precision of a machine tool. The machine tool includes a change detection unit that measures changes in quantity based on the operating environment and operating actions. The precision diagnostic device for the machine tool is characterized by having a change reference value recording unit that records a reference value for the change. The device acquires the change measured by the change detection unit and diagnoses changes in the precision of the machine tool based on a first change index and a second change index. The first change index is derived based on the magnitude of the change over a predetermined period, and the second change index is derived based on the current change and the reference value.

[0011] The invention of technical solution 2 is characterized in that, in the above structure, there is a precision diagnosis unit, which diagnoses the change in precision based on a first change index and derives a first diagnosis result, and diagnoses the change in precision based on a second change index and derives a second diagnosis result.

[0012] The invention of technical solution 3 is characterized in that, in the above structure, there is a precision score calculation unit, which calculates a first precision score after quantifying the magnitude of the influence of the change on the precision of the machine tool based on a first change index, and a second precision score after quantifying the magnitude of the influence of the change on the precision of the machine tool based on a second change index.

[0013] The invention of technical solution 4 is characterized in that, in the above structure, the accuracy diagnosis unit derives a first diagnosis result based on a first accuracy score and a second diagnosis result based on a second accuracy score, according to a predetermined threshold.

[0014] The invention of technical solution 5 is characterized in that, in the above structure, there is a diagnostic result notification unit that notifies the first diagnostic result and the second diagnostic result.

[0015] The invention of technical solution 6 is characterized in that, in the above structure, there is a precision countermeasure judgment unit, which determines a precision countermeasure to ensure the precision of the machine tool based on a combination of a first diagnostic result and a second diagnostic result.

[0016] The invention of technical solution 7 is characterized in that, in the above structure, there is a precision countermeasure execution unit, which executes or suspends the machining or on-machine measurement program in the machine tool according to the precision countermeasure determined by the precision countermeasure judgment unit.

[0017] The invention of technical solution 8 is characterized in that, in the above structure, the accuracy countermeasure judgment unit uses good or bad to represent the first diagnostic result and the second diagnostic result. If the first diagnostic result is bad, it is determined not to start or interrupt the machining and on-machine measurement in the machine tool until it becomes good again. If the first diagnostic result is good and the second diagnostic result is bad, it is determined to reset the correction value of the machine tool coordinates before starting or continuing the machining and on-machine measurement in the machine tool.

[0018] The invention of technical solution 9 is characterized in that, in the above structure, the accuracy countermeasure judgment unit uses good or bad to represent the first diagnostic result and the second diagnostic result, and if either the first diagnostic result or the second diagnostic result is bad, it is determined that the correction value of the machine tool coordinates should be reset.

[0019] The invention of technical solution 10 is characterized in that, in the above structure, the accuracy countermeasure judgment unit uses "good" or "bad" to represent the first diagnostic result and the second diagnostic result. When the second diagnostic result is bad and the first diagnostic result is good, it is determined that it is a suitable time to perform the following measurement, which is used to correct the accuracy of the machine tool.

[0020] The invention of technical solution 11 is characterized in that, in the above structure, the change is temperature.

[0021] The invention of technical solution 12 is a precision diagnosis method, wherein the precision of a machine tool is diagnosed, the machine tool is equipped with a change detection unit that measures the change amount that varies according to the setting environment and operating actions, characterized in that, in the precision diagnosis method of the machine tool, the change amount is obtained from the change detection unit, and the change in the precision of the machine tool is diagnosed based on a first change index and a second change index, the first change index being derived based on the magnitude of the change amount relative to a preset reference value over a predetermined period of time, and the second change index being derived based on the difference between the current change amount and the reference value.

[0022] Invention Effects

[0023] According to the inventions of technical solutions 1 and 12, by utilizing a first change index and a second change index derived from the amount of change that varies according to the machine tool's setup environment and operating actions, it is possible to diagnose the accuracy of a machine tool in any situation involving rapid changes and gradual changes.

[0024] According to the invention of technical solution 2, in addition to the above-mentioned effects, by diagnosing both the first change index and the second change index, it is possible to diagnose whether a drastic change or a long-term change has occurred.

[0025] According to the invention of technical solution 3, in addition to the above-mentioned effects, by providing continuous values ​​as accuracy scores, it is possible to determine the degree to which the accuracy is stable, rather than whether the machine tool's accuracy is good or bad.

[0026] According to the invention of technical solution 4, in addition to the above-mentioned effects, it is also possible to diagnose the accuracy of a machine tool based on the stability of its accuracy.

[0027] According to the invention of technical solution 5, in addition to the above-mentioned effects, by notifying the diagnostic results of the first change index and the second change index respectively, the operator can know whether a drastic change has occurred or a long-term change has occurred.

[0028] According to the invention of technical solution 6, in addition to the effects described above, by combining the first diagnostic result and the second diagnostic result to determine the countermeasures for ensuring the accuracy of the machine tool, it is possible to determine what processing should be performed to ensure the accuracy of the machine tool. Furthermore, in the event of any change, whether drastic or long-term, it is possible to appropriately determine the countermeasures for ensuring the accuracy of the machine tool.

[0029] According to the invention of technical solution 7, based on the above-mentioned effects, it is possible to perform processing and measurement while automatically ensuring the accuracy of the machine tool, thereby improving productivity.

[0030] According to the invention of technical solution 8, based on the above-mentioned effects, it is determined whether to start processing and measurement based on the magnitude of the current rate of change, and the appropriate time to re-set the coordinate correction value of the machine tool is determined based on the magnitude of the change since the last setting of the coordinate correction value, thereby ensuring the accuracy of processing and measurement.

[0031] According to the invention of technical solution 9, based on the above-mentioned effects, the appropriate time to re-set the coordinate correction value of the machine tool is determined according to the magnitude of the current rate of change and the magnitude of the change since the last setting of the coordinate correction value, especially in mass production processing, it can ensure both accuracy and productivity.

[0032] According to the invention of technical solution 10, based on the above-mentioned effects, it is determined whether a measurement is needed based on the magnitude of the change since the last correction, and whether a measurement with a small error can be performed based on the magnitude of the current rate of change. Thus, it is possible to determine the appropriate time to perform a measurement for correcting the accuracy of the machine tool.

[0033] According to the invention of technical solution 11, in addition to the above-mentioned effects, most of the changes in the accuracy of the machine tool are caused by thermal displacement, so it is possible to diagnose the changes in the accuracy of the machine tool caused by the influence of thermal displacement. Attached Figure Description

[0034] Figure 1 This is an explanatory diagram showing the machine tool of the present invention.

[0035] Figure 2 This is a block diagram illustrating the structure of the precision diagnostic device of the present invention.

[0036] Figure 3 (a) is a graph showing the update of the temperature reference value, (b) is a graph showing the change of the first temperature index, (c) is a graph showing the change of the first precision fraction, (d) is a graph showing the change of the second temperature index, and (e) is a graph showing the change of the second precision fraction.

[0037] Figure 4 This is an explanatory diagram of an example of a screen displaying diagnostic results for accuracy.

[0038] Figure 5 It is a flowchart used to determine the start time of processing and the setting time of the workpiece origin when processing workpieces with long processing times.

[0039] Figure 6 It is a flowchart used to determine the start time of processing and the setting time of the workpiece origin when repeatedly processing workpieces with short processing times.

[0040] Figure 7This is a flowchart used to determine the timing of the measurement in the case of a measurement for correcting accuracy.

[0041] Label Explanation

[0042] 1: 5-axis machining center; 4: Machine body temperature sensor; 5: Air temperature sensor; 6: Recording device; 7: Accuracy diagnostic device; 8: Display device; 103: Temperature reference value recording unit; 105: Temperature index calculation unit; 108: Accuracy score calculation unit; 112: Accuracy diagnostic unit; 116: Allowable range setting unit; 117: Accuracy countermeasure judgment unit; 118: Accuracy countermeasure teaching unit; 120: Accuracy countermeasure execution unit. Detailed Implementation

[0043] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0044] Figure 1 This is an explanatory diagram showing the machine tool of the present invention. Furthermore, Figure 1 The cover and other equipment are omitted, but the actual machine tool does have a cover and other equipment.

[0045] The 5-axis machining center 1, which serves as a machine tool, includes a spindle 2. The spindle 2 is used to mount tools (not shown) and to machine workpieces. Additionally, position sensors 3, such as contact probes, can be mounted for measurement.

[0046] In addition, the 5-axis machining center 1 is equipped with a body temperature sensor 4 as a change detection unit, an air temperature sensor 5, a recording device 6, a precision diagnostic device 7, a display device 8, and a control device 9.

[0047] Most changes in machine tool accuracy are caused by thermal displacement. Therefore, by using temperature as a measure of change, the accuracy changes caused by thermal displacement can be diagnosed.

[0048] Body temperature sensor 4 measures the body temperature, and air temperature sensor 5 measures the ambient air temperature around the body. The temperature information measured by body temperature sensor 4 and air temperature sensor 5 is imported and recorded in recording device 6.

[0049] The accuracy diagnostic device 7 diagnoses the impact of temperature changes on the accuracy of the 5-axis machining center 1 based on the temperature information imported into the recording device 6.

[0050] Display device 8, for example, is an operation panel that displays the diagnostic results of accuracy diagnostic device 7 on a screen. In addition to the diagnostic results displayed on display device 8, warning lights (not shown) and buzzers (not shown) can also be used to notify the operator.

[0051] The control device 9 determines countermeasures to ensure the accuracy of the 5-axis machining center 1 based on the diagnostic results sent from the accuracy diagnostic device 7, and controls the machining and measurement actions of the workpiece based on the determined countermeasures.

[0052] Next, the accuracy diagnostic device 7 will be described in detail.

[0053] Figure 2 This is a block diagram illustrating the structure of the accuracy diagnostic device 7 of the present invention.

[0054] The accuracy diagnostic device 7 includes a temperature reference value recording unit 103, a temperature index calculation unit 105, an accuracy score calculation unit 108, an accuracy score display unit 111, an accuracy diagnostic unit 112, an allowable range setting unit 116, an accuracy countermeasure judgment unit 117, an accuracy countermeasure teaching unit 118, an accuracy countermeasure execution unit 120, and a diagnostic result notification unit 122.

[0055] The function of the accuracy diagnostic device 7 is explained below.

[0056] First, the precision diagnostic device 7 acquires temperature information, i.e., temperature data 101, measured by the machine body temperature sensor 4 and the air temperature sensor 5 and recorded in the recording device 6. Upon receiving the temperature reference value recording command 102, the acquired temperature data 101 is recorded as a temperature reference value 104 in the temperature reference value recording unit 103. Furthermore, the temperature reference value recording command 102 can be executed by operating the control panel and screen of the 5-axis machining center 1, or by executing a specific program code. Alternatively, it can be executed automatically in conjunction with specific actions such as rewriting prescribed parameters and power-on. The temperature reference value 104 can also be preset before workpiece machining and measurement, independent of the temperature reference value recording command 102.

[0057] Next, the temperature index calculation unit 105 calculates the first temperature index 106 as the first change index and the second temperature index 107 as the second change index.

[0058] The first temperature index 106 is, for example, the rate of temperature change. The first temperature index 106 is calculated using Equation 1. In the following equation, θ represents the measured temperature value, and Θ represents the calculated temperature index. The current temperature θ(t) and the temperature θ(t-Δt) before a specified time Δt are obtained from the recording device 6 as temperature data 101, and the rate of temperature change per unit time is calculated using the difference between the current temperature θ(t) and the temperature θ(t-Δt) before the specified time Δt. θ (t) is converted to calculate the first temperature index Θ1(t)(106).

[0059]

[0060] Θ1(t): Primary temperature index (°C / hour)

[0061] Δt: Time interval (s)

[0062] θ(t): Measurement temperature (°C)

[0063] Measure the rate of temperature change (°C / s)

[0064] Equation 1 is one example of a method for calculating the rate of change, but other known numerical differentiation methods can also be used. For example, as disclosed in Patent Document 1, the rate of change can be approximately calculated based on the body temperature and the ambient temperature. Furthermore, although the first temperature index 106 is used as the rate of temperature change, the first temperature index 106 can be any index that represents the drastic degree of temperature change over a short period of time. In addition to the rate of temperature change, the difference between the maximum and minimum values ​​within a specified time period can also be used as the first temperature index 106.

[0065] The second temperature index 107 is the difference between the temperature reference value 104 (θ0) and the current temperature θ (t). The second temperature index 107 is calculated using Equation 2.

[0066] Θ2(t)=θ(t)-θ0 (Equation 2)

[0067] Next, the precision fraction calculation unit 108 calculates the first precision fraction 109 based on the first temperature index 106, and calculates the second precision fraction 110 based on the second temperature index 107. The first precision fraction 109 and the second precision fraction 110 are calculated, for example, using Equation 3.

[0068]

[0069] S n (t): Precision fraction (n=1 first precision fraction, n=2 second precision fraction)

[0070] S min Precision fraction at its worst accuracy

[0071] S max Precision fraction when accuracy is optimal

[0072] Θ n (t): Temperature index (n=1 First temperature index, n=2 Second temperature index)

[0073] Θ A Θ B :constant

[0074] In Equation 3, the precision fraction S n(t) by S min To S max The values ​​between these ranges are represented. The absolute value of the first temperature index 106 is greater than the constant Θ. A At that time, the first precision fraction 109 is the worst, which is less than the constant Θ. B At that time, the first precision fraction 109 is the best. Similarly, the value of the second temperature index 107 is greater than the constant Θ. A When the value is large, the second precision fraction 110 is the worst, in terms of the ratio constant Θ. B For hours, the second-precision fraction is the best.

[0075] In addition, Equation 3 is an example of a method for calculating the precision fractions 109 and 110. Other known formulas may also be used in the calculation of the precision fractions 109 and 110.

[0076] Figure 3 (a) to (e) represent examples of calculating the changes of the first precision fraction 109 and the second precision fraction 110 relative to a certain temperature using Equations 1 to 3.

[0077] Figure 3 (a) is a graph showing the updates to the temperature reference value 104. The solid line represents the temperature change over time, while the dashed line represents the temperature reference value 104. In this example, at the times of 0 hours and 3 hours, the temperature reference value recording instruction 102 is invoked to record the temperature θ(t) at that time as the temperature reference value θ0(104). The temperature reference value θ0(104) changes in a stepwise manner at the times when the temperature reference value recording instruction 102 is invoked.

[0078] Figure 3 (b) is a graph representing the change of the first temperature index Θ1(t)106. Here, according to Equation 1, the first temperature index Θ1(t) is calculated by numerically differentiating the temperature θ(t). Figure 3 As shown in (a), the temperature decreases gradually during the first 1 hour, so the first temperature index Θ1(t)(106) is negative. On the other hand, the temperature rises sharply during the second to fourth hour, so the first temperature index Θ1(t)(106) is positive.

[0079] Figure 3 (c) is a graph representing the change in the first precision fraction 109. Here, S in Equation 3 is... max Set S to 100. minThe accuracy score S(t) is set to 0. When the temperature change is small and the accuracy of the 5-axis machining center 1 is stable, the accuracy score S(t) is 100. On the other hand, the accuracy score S(t) is calculated according to the values ​​of 10 scales, so that the greater the temperature change, the more unstable the accuracy, and the closer the accuracy score S(t) is to 0. Here, the accuracy diagnosis unit 112 judges the first accuracy score 109 as good if it is 60 or above, and diagnoses it as bad if it is 50 or below. In addition, the threshold for judging whether it is good or bad (the allowable range 115 described later) is set by the allowable range setting unit 116.

[0080] like Figure 3 As shown in (a), when the temperature change is gradual from 0 to 2 hours, the first precision fraction 109 is shown as 100, and when the temperature rises sharply from 2 to 4 hours, the value of the first precision fraction 109 decreases.

[0081] Figure 3 (d) is a graph representing the change of the second temperature index Θ2(t)107. According to Equation 2, the difference between temperature θ(t) and the temperature reference value θ0104 is calculated as the second temperature index Θ2(t)107. At the time when the temperature reference value recording instruction 102 is indicated, that is, at the times when 0 hours and 3 hours have passed, temperature θ(t) is equal to the temperature reference value θ0104, therefore, at each time, the value of the second temperature index Θ2(t)107 is 0.

[0082] Figure 3 (e) is a graph representing the change in the second precision fraction 110. Here, similarly to the first precision fraction 109, S in Equation 3 is... max Set S to 100. min Set to 0. Here, the accuracy diagnosis unit 112 judges a second accuracy score 110 of 60 or above as good, and diagnoses a score of 50 or below as bad. In addition, the threshold for judging whether it is good or bad (the allowable range 115 described later) is set by the allowable range setting unit 116.

[0083] like Figure 3 As shown in (d), at the times of 0 hours and 3 hours, the temperature θ(t) at each time point differs from the temperature reference value 104 by 0, therefore the second precision fraction 110 shows 100. On the other hand, as the temperature changes over time, the value of the second precision fraction 110 decreases.

[0084] The calculated first accuracy score 109 and second accuracy score 110 become the standards for judging whether the machining and measurement accuracy of the current workpiece is good or bad. Therefore, the accuracy score display unit 111 displays the accuracy score on the display device 8. In addition, the accuracy diagnosis unit 112 diagnoses whether the accuracy of the current 5-axis machining center 1 is good or bad. The tolerance range setting unit 116 sets the tolerance range 115 of the first accuracy score 109 and the second accuracy score 110, for example, by inputting values ​​on the operation panel and by using a program. Furthermore, the tolerance range 115 can be arbitrarily changed by the tolerance range setting unit 116. The accuracy diagnosis unit 112 compares the set tolerance range 115 with the first accuracy score 109 and the second accuracy score 110 respectively to perform diagnosis. Regarding the diagnosis results, the diagnosis result for the first accuracy score 109 is set as the first diagnosis result 113, and the diagnosis result for the second accuracy score 110 is set as the second diagnosis result 114.

[0085] The accuracy countermeasure judgment unit 117 determines whether accuracy countermeasures are needed to correct the accuracy of the 5-axis machining center 1 based on a combination of the good / bad condition of the first diagnostic result 113 and the good / bad condition of the second diagnostic result 114. Furthermore, if accuracy countermeasures are needed, it determines what kind of accuracy countermeasures should be performed. When showing the operator the accuracy countermeasures determined by the accuracy countermeasure judgment unit 117 and instructing them to execute them, the accuracy countermeasure teaching unit 118 outputs the accuracy countermeasures as a message 119 to the display device 8. On the other hand, when the 5-axis machining center 1 is made to automatically execute the accuracy countermeasures determined by the accuracy countermeasure judgment unit 117, the accuracy countermeasure execution unit 120 outputs control commands 121.

[0086] Message 119 is generated based on the results of the first diagnostic result 113 and the second diagnostic result 114, respectively. For example, if the first diagnostic result 113 is unfavorable, it indicates that machining and measurement should be interrupted. Alternatively, if the second diagnostic result 114 is unfavorable, it indicates the necessary accuracy countermeasures, such as correcting the coordinates of the workpiece origin, etc., for remeasurement. In this case, to make Message 119 more clearly visible, an alarm may also be displayed. In particular, if the diagnostic results indicate a deterioration in accuracy, in addition to displaying Message 119 by the accuracy countermeasure teaching unit 118, a control command 121 to stop the operation of the 5-axis machining center 1 via a program may also be output to the accuracy countermeasure execution unit 120. Furthermore, the output of Message 119 by the accuracy countermeasure teaching unit 118 is not limited to the display device 8; it may also be a notification email sent to a terminal owned by the operator. Additionally, it may be output other than text-based output, such as the illumination of warning lights or alarms.

[0087] Control command 121 is generated based on the results of the first diagnostic result 113 and the second diagnostic result 114. For example, if the first diagnostic result 113 is unfavorable, control command 121 is generated to interrupt machining and measurement. Alternatively, if the second diagnostic result 114 is unfavorable, control command 121 is generated to perform necessary accuracy countermeasures, such as re-measuring the correction values ​​of the workpiece origin coordinates. The generated control command 121 is output to the control device 9. The control device 9 automatically executes the required control of the 5-axis machining center 1 according to the input control command 121.

[0088] The diagnostic result notification unit 122 notifies the user by displaying the first diagnostic result 113 and the second diagnostic result 114 on the display device 8. The display of the diagnostic results allows the user to know whether the first diagnostic result 113 and the second diagnostic result 114 are good or bad. Furthermore, the notification method is not limited to displaying the diagnostic results on the display device 8; it can also be a notification email sent to a terminal owned by the operator. Alternatively, it can be an output other than text-based output, such as illuminating a warning light or issuing an alarm. Moreover, the notification method can be changed depending on the combination of whether the first diagnostic result 113 and the second diagnostic result 114 are good or bad. For example, if the first diagnostic result 113 worsens, an alarm can be generated in addition to the display on the display device 8; if the second diagnostic result 114 worsens, only the display on the display device 8 will be shown. Alternatively, an alarm can be generated only when both the first diagnostic result 113 and the second diagnostic result 114 worsen, and only the display on the display device 8 will be shown otherwise.

[0089] Figure 4 This is an example of the screen display of a display device 8 equipped with a precision score display unit 111, a tolerance range setting unit 116, and a precision countermeasure teaching unit 118.

[0090] The system displays the values ​​of the first accuracy score 109 and the second accuracy score 110, along with bar charts visually representing their magnitudes. Additionally, it displays the allowable range 115 set by the allowable range setting unit 116 for each of the first accuracy score 109 and the second accuracy score 110. Furthermore, it displays messages 119 generated by the accuracy countermeasure teaching unit 118 for each of the first accuracy score 109 and the second accuracy score 110. Thus, by displaying the accuracy score, allowable range 115, and message 119 on a single screen, the accuracy of the 5-axis machining center 1 and its accuracy diagnostic criteria can be visually assessed. Furthermore, the displayed information is not limited to the information described above; for example, it may display... Figure 3 The graph shown can also display information such as spindle speed, which indicates the movement of the 5-axis machining center 1.

[0091] Hereinafter, using judgment examples 1 to 3, we will explain the judgment method of the accuracy countermeasure of the accuracy countermeasure judgment unit 117 and the accuracy countermeasure implemented.

[0092] Judgment Example 1 envisions a scenario involving processing and on-machine measurement for a relatively long period of time, such as more than one hour.

[0093] Figure 5 This is a flowchart used to determine the start time of processing and the time of setting the workpiece origin when processing workpieces with long processing times. Specifically, it is a flowchart illustrating the judgment method of the accuracy countermeasure judgment unit 117 in Judgment Example 1 and the accuracy countermeasures implemented. Regarding the timing of the diagnosis in Judgment Example 1, it is mainly performed at the start of workpiece processing and on-machine measurement.

[0094] The longer the machining and on-machine measurement time, the more susceptible the accuracy of the machining and on-machine measurement becomes to the effects of thermal displacement caused by temperature changes. Furthermore, if machining and on-machine measurement begin under conditions of rapid temperature change, they will be significantly affected by thermal displacement. Therefore, for high-precision machining and on-machine measurement, it is preferable to wait until the temperature change has slowed down before starting. If the coordinate correction values ​​for the workpiece origin, etc., are measured and set after the temperature change has slowed down before starting machining and on-machine measurement, high precision can be achieved.

[0095] First, check whether the first accuracy fraction 109 is within the allowable range 115 (S11). If the first accuracy fraction 109 is within the allowable range 115, i.e., when the temperature change is gradual, proceed to S13. On the other hand, if the first accuracy fraction 109 is not within the allowable range 115, i.e., when the temperature change is rapid, the accuracy of processing and measurement may deteriorate. Therefore, proceed to S12, and do not start processing and measurement until the first accuracy fraction 109 is within the allowable range 115.

[0096] Next, it is checked whether the second accuracy fraction 110 is within the allowable range 115 (S13). If the second accuracy fraction 110 is within the allowable range 115, proceed to S16 and immediately begin machining or measurement. If the second accuracy fraction 110 is not within the allowable range 115, i.e., if the temperature has changed significantly since the last time the temperature reference value 104 was set, proceed to S14, measure and set the correction values ​​for coordinates such as the workpiece origin. For example, the workpiece origin position is measured using a contact probe, which is the position measuring sensor 3, and the workpiece origin offset value is updated. The temperature at that moment is recorded as the temperature reference value 104 (S15). Through this process, the difference between the current temperature and the temperature reference value 104 becomes 0, so the second accuracy fraction 110 converges within the allowable range 115, achieving a state of good accuracy. Afterward, machining or measurement begins (S16).

[0097] Such processing can be performed only at the start of workpiece machining and on-machine measurement, or it can be performed at predetermined times during machining and on-machine measurement, in addition to the start of workpiece machining and on-machine measurement. If the above processing is performed at predetermined times during machining and on-machine measurement, in S12, machining or on-machine measurement is interrupted until the first accuracy fraction 109 falls within the allowable range 115. Once the first accuracy fraction 109 falls within the allowable range 115, machining or on-machine measurement resumes.

[0098] In addition, in Judgment Example 1, it is envisioned that accuracy countermeasures are automatically executed by the accuracy countermeasure execution unit 120, but the operator can also execute the required accuracy countermeasures according to the instruction of the accuracy countermeasure teaching unit 118. In this case, in S12, the accuracy countermeasure teaching unit 118 teaches the operator by displaying a message 119 on the display device 8 that a rapid temperature change is currently occurring and therefore it is necessary to wait until the temperature change subsides, or by sounding an alarm. In S14, the situation where it is necessary to measure and set the correction value of the coordinates is taught.

[0099] By implementing appropriate accuracy measures as described above, the accuracy of machining and on-machine measurements can be ensured.

[0100] Judgment Example 2 envisions a mass production process where the processing time for each workpiece is, for example, a relatively short period of a few minutes to less than an hour, and the same processing is performed repeatedly.

[0101] Figure 6This is a flowchart used to determine the start time of machining and the setting time of the workpiece origin when repeatedly machining workpieces with short machining times. Specifically, it is a flowchart illustrating the judgment method of the accuracy countermeasure judgment unit 117 in Judgment Example 2 and the accuracy countermeasures to be implemented. The diagnosis in Judgment Example 2 is performed at the end of machining each of the first or a predetermined number of workpieces.

[0102] In mass production, not only is precision required, but also the productivity to process a large number of workpieces in a short time. Therefore, diagnostics are performed by measuring coordinate correction values ​​such as tool length offset and workpiece origin at the minimum time required to ensure precision. Under conditions of rapid temperature changes, even short-term precision can deteriorate, so diagnostics need to be performed after each workpiece is processed. On the other hand, under conditions of gradual temperature changes, diagnostics are performed when the temperature change relative to the last diagnostic is large.

[0103] First, check if the first accuracy fraction 109 is within the allowable range 115 (S21). If the first accuracy fraction 109 is within the allowable range 115, i.e., the temperature change is gradual, proceed to S22. On the other hand, if the first accuracy fraction 109 is not within the allowable range 115, i.e., the temperature change is rapid, even a short time may cause the accuracy to deteriorate, therefore proceed to S23, where coordinate correction values ​​for tool length offset and workpiece origin, etc., are measured and set. Then, the temperature at that moment is recorded as the temperature reference value 104 (S24). Through this process, even under rapid temperature changes, deviations in the workpiece's machining accuracy can be minimized. After that, machining of the next workpiece begins (S25).

[0104] Next, when the temperature change is gradual, check whether the second accuracy fraction 110 is within the allowable range 115 (S22). If the second accuracy fraction 110 is not within the allowable range 115, that is, when the temperature change is large relative to the time when the coordinate correction values ​​for tool length offset and workpiece origin were last measured and set, the accuracy may deteriorate due to the gradual temperature changes that occur during long-term use. Therefore, the coordinate correction value is measured and set again (S23). Then, the temperature at that moment is recorded as the temperature reference value 104 (S24). Through this process, the difference between the current temperature and the temperature reference value 104 becomes 0, so the second accuracy fraction 110 converges within the allowable range 115, achieving a state of good accuracy. After that, the machining of the next workpiece begins (S25).

[0105] Regarding the measurement in S23, the precision countermeasure execution unit 120 can output a command to the control device 9, thereby the machine tool can automatically perform the measurement using position measuring sensors 3 such as contact probes. Alternatively, the operator can display the required measurement status through messages 119 of the precision countermeasure teaching unit 118.

[0106] As mentioned above, whether the temperature changes drastically or gradually, by measuring the coordinate correction values ​​of tool length offset and workpiece origin at the appropriate time, both accuracy and productivity can be ensured.

[0107] Judgment Example 3 envisions a measurement used to correct the accuracy of a machine tool.

[0108] Figure 7 This is a flowchart used to determine the timing of a measurement in order to correct its accuracy. Specifically, it is a flowchart illustrating the judgment method of the accuracy countermeasure judgment unit 117 in Judgment Example 3 and the implemented accuracy countermeasures.

[0109] In the 5-axis machining center 1, error parameters such as the center position of the rotary axes, the scale positioning of the linear axes, and the tilt of the linear axes relative to each other are measured and corrected accordingly to improve accuracy. However, measuring and correcting various error parameters takes a considerable amount of time. For example, when the temperature changes drastically during the measurement of error parameters, the measurement error increases, making it impossible to obtain sufficient accuracy improvement based on corrections. Furthermore, although high accuracy can be ensured by frequently performing corrections, production cannot be carried out during the measurement period, so measurements must be performed at the minimum necessary time. Therefore, the accuracy diagnostic device 7 determines the optimal time to perform measurements for accuracy correction while considering both accuracy improvement and productivity.

[0110] First, it is checked whether the second precision fraction 110 is within the allowable range 115 (S31). If the second precision fraction 110 is within the allowable range 115, that is, if the temperature change is small since the last correction, it is determined that no correction is needed and the measurement is not performed (S32). On the other hand, if the second precision fraction 110 is not within the allowable range 115, that is, if the temperature change is large since the last correction, it is determined that a correction is needed. However, if a correction is performed during a rapid temperature change, the measurement error will increase. Therefore, it is checked whether the first precision fraction 109 is within the allowable range 115 (S33) to confirm the state of temperature change. If the first precision fraction 109 is not within the allowable range 115, that is, if a rapid temperature change has occurred, a correction is not performed immediately, but rather when the temperature change becomes gradual and the first precision fraction 109 falls within the allowable range 115. When the first precision fraction 109 is within the allowable range 115, the temperature change is gradual, thus allowing for high-precision measurement of the error parameter. Therefore, a correction is applied by measuring the error parameter (S35). Then, the temperature at that moment is recorded as the temperature reference value 104 (S36). Through this process, the difference between the current temperature and the temperature reference value 104 becomes 0, thus the second precision fraction 110 converges within the allowable range 115, achieving a state of good accuracy.

[0111] Regarding the measurement in S35, the precision countermeasure execution unit 120 can output a command to the control device 9, and the machine tool can automatically perform the measurement by using position measuring sensors 3 such as contact probes. Alternatively, the operator can be taught the situation to be measured by the message 119 of the precision countermeasure teaching unit 118.

[0112] As described above, it is possible to determine the optimal time to perform measurements to correct the accuracy of machine tools, thus achieving both accuracy improvement and productivity.

[0113] The accuracy diagnostic device 7 described above includes: a temperature reference value recording unit 103 that records a temperature reference value 104 in a 5-axis machining center 1 equipped with a body temperature sensor 4 and an air temperature sensor 5 that measure the temperature that changes according to the operating environment and operation; acquiring temperature data 101 measured by the body temperature sensor 4 and the air temperature sensor 5; and diagnosing changes in the accuracy of the 5-axis machining center 1 based on a first change index (first temperature index 106) derived from the magnitude of temperature change over a predetermined period of time and a second change index (second temperature index 107) derived from the current temperature and the temperature reference value 104.

[0114] The accuracy diagnostic device 7 configured in this manner can diagnose the accuracy of the 5-axis machining center 1 for any situation involving abrupt temperature changes and gradual temperature changes by utilizing a first temperature index 106 and a second temperature index 107 derived from the temperature changes based on the setup environment and operation of the 5-axis machining center 1.

[0115] In addition, the precision diagnostic device 7 includes a precision diagnostic unit 112, which diagnoses the changes in the precision of the 5-axis machining center 1 based on a first temperature index 106 and derives a first diagnostic result 113, and diagnoses the changes in the precision of the 5-axis machining center 1 based on a second temperature index 107 and derives a second diagnostic result 114.

[0116] Therefore, by diagnosing the first temperature index 106 and the second temperature index 107, it is possible to diagnose whether a rapid temperature change or a long-term temperature change has occurred, respectively.

[0117] In addition, the accuracy diagnostic device 7 includes an accuracy score calculation unit 108, which calculates a first accuracy score 109, which is a numerical representation of the effect of temperature on the accuracy of the 5-axis machining center 1 based on a first temperature index 106, and a second accuracy score 110, which is a numerical representation of the effect of temperature on the accuracy of the 5-axis machining center 1 based on a second temperature index 107.

[0118] Therefore, by providing continuous values ​​as the first precision fraction 109 and the second precision fraction 110, it is possible to determine the degree to which the precision is stable, rather than whether the precision of the 5-axis machining center 1 is good or poor.

[0119] In addition, the accuracy diagnostic unit 112 derives a first diagnostic result 113 based on the first accuracy score 109 and a second diagnostic result 114 based on the second accuracy score 110, according to the allowable range 115.

[0120] Therefore, by considering the stability of the accuracy of the 5-axis machining center 1, it is possible to diagnose the quality of the accuracy of the 5-axis machining center 1.

[0121] In addition, the accuracy diagnostic device 7 also includes an accuracy countermeasure judgment unit 117, which judges the accuracy countermeasures for ensuring the accuracy of the 5-axis machining center 1 by combining the first diagnostic result 113 and the second diagnostic result 114.

[0122] Therefore, by combining the first diagnostic result 113 and the second diagnostic result 114, it is possible to determine the countermeasures for ensuring the accuracy of the 5-axis machining center 1, and thus determine what processing should be performed to ensure the accuracy of the 5-axis machining center 1. Furthermore, in the event of either a rapid temperature change or a long-term temperature change, it is possible to appropriately determine the countermeasures for ensuring the accuracy of the 5-axis machining center 1.

[0123] In addition, the accuracy diagnostic device 7 includes an accuracy countermeasure execution unit 120, which executes or stops the machining process in the 5-axis machining center 1 or the temperature measurement of the machine body temperature sensor 4 and the air temperature sensor 5 based on the accuracy countermeasure determined by the accuracy countermeasure judgment unit 117.

[0124] Therefore, it is possible to automatically ensure the accuracy of the 5-axis machining center 1 while performing machining and measurement, thus improving productivity.

[0125] The invention has been described above based on the illustrated examples, but its technical scope is not limited thereto. For example, the machine tool may also be a machine tool other than a 5-axis machining center.

[0126] Furthermore, the change in the underlying variable is not limited to temperature; it can also be, for example, load value.

Claims

1. A precision diagnostic device for a machine tool, comprising diagnosing the precision of the machine tool, wherein the machine tool includes a change detection unit that measures changes in a quantity that varies according to the setup environment and operating actions, characterized in that... The machine tool's accuracy diagnostic device includes a change reference value recording unit, which records the reference value of the change. In the precision diagnostic device of the machine tool, The change measured by the change detection unit is obtained. The machine tool's accuracy variation is diagnosed based on a first variation index and a second variation index, wherein the first variation index is derived based on the magnitude of the change in the amount of change over a specified period of time, and the second variation index is derived based on the current amount of change and the reference value. The change benchmark value recording unit records and updates the benchmark value at time intervals longer than the predetermined time when the first change index was derived. The machine tool's accuracy diagnostic device further comprises: an accuracy diagnostic unit that diagnoses changes in accuracy based on the first change index and derives a first diagnostic result, and diagnoses changes in accuracy based on the second change index and derives a second diagnostic result; and an accuracy countermeasure judgment unit that determines accuracy countermeasures to ensure the accuracy of the machine tool based on a combination of the first diagnostic result and the second diagnostic result. The accuracy countermeasure judgment unit uses "good" or "bad" to represent the first diagnostic result and the second diagnostic result. If the first diagnostic result is unfavorable, it is determined that machining on the machine tool and on-machine measurement will not be started or interrupted until the result becomes favorable again. If the first diagnostic result is good and the second diagnostic result is bad, it is determined that the coordinate correction values ​​of the machine tool should be reset before starting or continuing machining and on-machine measurement.

2. A precision diagnostic device for a machine tool, comprising diagnosing the precision of the machine tool, wherein the machine tool includes a change detection unit that measures changes in a quantity that varies according to the setup environment and operating actions, characterized in that... The machine tool's accuracy diagnostic device includes a change reference value recording unit, which records the reference value of the change. In the precision diagnostic device of the machine tool, The change measured by the change detection unit is obtained. The machine tool's accuracy variation is diagnosed based on a first variation index and a second variation index, wherein the first variation index is derived based on the magnitude of the change in the amount of change over a specified period of time, and the second variation index is derived based on the current amount of change and the reference value. The change benchmark value recording unit records and updates the benchmark value at time intervals longer than the predetermined time when the first change index was derived. The machine tool's accuracy diagnostic device further comprises: an accuracy diagnostic unit that diagnoses changes in accuracy based on the first change index and derives a first diagnostic result, and diagnoses changes in accuracy based on the second change index and derives a second diagnostic result; and an accuracy countermeasure judgment unit that determines accuracy countermeasures to ensure the accuracy of the machine tool based on a combination of the first diagnostic result and the second diagnostic result. The accuracy countermeasure judgment unit uses "good" or "bad" to represent the first diagnostic result and the second diagnostic result. If either the first diagnostic result or the second diagnostic result is unfavorable, it is determined that the coordinate correction values ​​of the machine tool should be reset.

3. A precision diagnostic device for a machine tool, comprising diagnosing the precision of the machine tool, wherein the machine tool includes a change detection unit that measures changes in a quantity that varies according to the setup environment and operating actions, characterized in that... The machine tool's accuracy diagnostic device includes a change reference value recording unit, which records the reference value of the change. In the precision diagnostic device of the machine tool, The change measured by the change detection unit is obtained. The machine tool's accuracy variation is diagnosed based on a first variation index and a second variation index, wherein the first variation index is derived based on the magnitude of the change in the amount of change over a specified period of time, and the second variation index is derived based on the current amount of change and the reference value. The change benchmark value recording unit records and updates the benchmark value at time intervals longer than the predetermined time when the first change index was derived. The machine tool's accuracy diagnostic device further comprises: an accuracy diagnostic unit that diagnoses changes in accuracy based on the first change index and derives a first diagnostic result, and diagnoses changes in accuracy based on the second change index and derives a second diagnostic result; and an accuracy countermeasure judgment unit that determines accuracy countermeasures to ensure the accuracy of the machine tool based on a combination of the first diagnostic result and the second diagnostic result. The accuracy countermeasure judgment unit uses "good" or "bad" to represent the first diagnostic result and the second diagnostic result. If the second diagnostic result is unfavorable and the first diagnostic result is favorable, it is determined that it is a suitable time to perform the following measurement, which is used to correct the accuracy of the machine tool.

4. The precision diagnostic device for machine tools according to any one of claims 1 to 3, characterized in that, The precision diagnostic device for the machine tool includes a precision score calculation unit, which calculates a first precision score, which quantifies the magnitude of the impact of the change on the precision of the machine tool based on the first change index, and a second precision score, which quantifies the magnitude of the impact of the change on the precision of the machine tool based on the second change index.

5. The machine tool precision diagnostic device according to claim 4, characterized in that, The accuracy diagnostic unit derives the first diagnostic result based on the first accuracy score and the second diagnostic result based on the second accuracy score, according to a predetermined threshold.

6. The precision diagnostic device for a machine tool according to any one of claims 1 to 3, characterized in that, The precision diagnostic device for the machine tool includes a diagnostic result notification unit, which notifies the first diagnostic result and the second diagnostic result.

7. The machine tool precision diagnostic device according to any one of claims 1 to 3, characterized in that, The precision diagnostic device for the machine tool includes a precision countermeasure execution unit, which executes or suspends the machining or on-machine measurement program performed on the machine tool according to the precision countermeasure determined by the precision countermeasure judgment unit.

8. The machine tool precision diagnostic device according to any one of claims 1 to 3, characterized in that, The change is in temperature.

9. A method for diagnosing the accuracy of a machine tool, wherein, The machine tool is equipped with a change detection unit that measures the change in accuracy based on the setup environment and operating actions. The machine tool is characterized by... In the machine tool accuracy diagnosis method, The change amount is obtained from the change detection unit. The machine tool's accuracy change is diagnosed based on a first change index and a second change index, and a first diagnostic result and a second diagnostic result are derived. The first change index is derived based on the magnitude of the change relative to a preset reference value over a predetermined period of time, and the second change index is derived based on the difference between the current change and the reference value. Based on the combination of the first diagnostic result and the second diagnostic result, accuracy countermeasures to ensure the machine tool's accuracy are determined. The benchmark value is recorded and updated at time intervals longer than the specified time when the first change index was derived. The first and second diagnostic results are represented using the terms "good" or "bad". If the first diagnostic result is unfavorable, it is determined that machining on the machine tool and on-machine measurement will not be started or interrupted until the result becomes favorable again. If the first diagnostic result is good and the second diagnostic result is bad, it is determined that the coordinate correction values ​​of the machine tool should be reset before starting or continuing machining and on-machine measurement.

10. A method for diagnosing the accuracy of a machine tool, wherein, The machine tool is equipped with a change detection unit that measures the change in accuracy based on the setup environment and operating actions. The machine tool is characterized by... In the machine tool accuracy diagnosis method, The change amount is obtained from the change detection unit. The machine tool's accuracy change is diagnosed based on a first change index and a second change index, and a first diagnostic result and a second diagnostic result are derived. The first change index is derived based on the magnitude of the change relative to a preset reference value over a predetermined period of time, and the second change index is derived based on the difference between the current change and the reference value. Based on the combination of the first diagnostic result and the second diagnostic result, accuracy countermeasures to ensure the machine tool's accuracy are determined. The benchmark value is recorded and updated at time intervals longer than the specified time when the first change index was derived. The first and second diagnostic results are represented using the terms "good" or "bad". If either the first diagnostic result or the second diagnostic result is unfavorable, it is determined that the coordinate correction values ​​of the machine tool should be reset.

11. A method for diagnosing the accuracy of a machine tool, wherein, The machine tool is equipped with a change detection unit that measures the change in accuracy based on the setup environment and operating actions. The machine tool is characterized by... In the machine tool accuracy diagnosis method, The change amount is obtained from the change detection unit. The machine tool's accuracy change is diagnosed based on a first change index and a second change index, and a first diagnostic result and a second diagnostic result are derived. The first change index is derived based on the magnitude of the change relative to a preset reference value over a predetermined period of time, and the second change index is derived based on the difference between the current change and the reference value. Based on the combination of the first diagnostic result and the second diagnostic result, accuracy countermeasures to ensure the machine tool's accuracy are determined. The benchmark value is recorded and updated at time intervals longer than the specified time when the first change index was derived. The first and second diagnostic results are represented using the terms "good" or "bad". If the second diagnostic result is unfavorable and the first diagnostic result is favorable, it is determined that it is a suitable time to perform the following measurement, which is used to correct the accuracy of the machine tool.

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