Diagnostic device

Abstract

To provide a diagnostic device which does not require mechanical data on factors of processing errors to be collected during processing, and which enables also inexperienced operators to easily and reliably diagnose factors of processing errors.SOLUTION: A diagnostic device is provided with: an error transition recording section 2 in which deviation data A-F of multiple kinds is recorded; an error transition input section 3 for selecting one piece of deviation data from the deviation data A-F of multiple kinds; an error factor recording section 9 in which factors of multiple kinds are recorded in association with the deviation data A-F respectively; a factor diagnosis section 6 for specifying a factor on the basis of the deviation data selected by the error transition input section 3, by referring to the error factor recording section 9; and a display section 7 for displaying the factor specified by the factor diagnosis section 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a diagnostic device for diagnosing the cause of machining errors in a workpiece machined by a machine tool such as an NC device. [Background technology]

[0002] When checking the dimensions and shape of a workpiece machined by a machine tool with a measuring instrument, etc., if the machining error is large, it is necessary to investigate the cause and take measures. There are several possible causes for such machining errors, such as poor accuracy of the machine tool, thermal displacement, tool wear, measurement error of the machining origin, measurement error of the tool offset compensation value, etc. Therefore, in a general investigation, the machine tool operator first checks the measurement error of the machining origin and the tool offset compensation value, tool wear, etc. Then, if there is no problem, the manufacturer will inspect the positioning accuracy of the machine with a laser length measuring machine, measure the inverted protrusion with a double ball bar device, etc., and perform an accuracy inspection of the machine tool. Therefore, it often takes a long time to investigate the cause of the machining error.

[0003] Therefore, in order to diagnose the cause of the machining error in a short time, the diagnostic device described in Patent Document 1 classifies the causes of the machining error into multiple categories, such as tool factors including tool wear, machine factors including poor accuracy of the machine tool, and fixture factors including poor fixation of the workpiece, and extracts and stores the feature values ​​of the machine data and the measurement data of the workpiece for each factor. Then, when the detected amount of the machine data or the measurement data of the workpiece detected during machining is close to the previously stored feature value, it is determined that the factor associated with the feature value is the cause of the machining error, thereby enabling the cause of the machining error to be diagnosed in a short time. In addition, the diagnostic device described in Patent Document 2 obtains the amount of thermal displacement due to the internal heat source of the machine tool and the amount of thermal displacement due to environmental temperature change, and displays the tool offset correction value, temperature, and thermal displacement correction value over time related to each thermal displacement amount in a graph. Then, the operator can easily check the graph display to see whether the actual thermal displacement and tool wear match the operator's experiential sense. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-206056 A [Patent Document 2] Patent No. 6001211 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the diagnostic devices described in Patent Documents 1 and 2 require the collection of machine data during machining, making the entire device large-scale and creating a problem in terms of cost. In addition, the diagnostic device described in Patent Document 2 in particular displays information related to the current machining, but diagnoses the cause of machining errors from the display, requiring sufficient experience, which creates a problem in that it is difficult for inexperienced workers to diagnose the cause.

[0006] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a diagnostic device which does not require collection of machine data that may be a cause of machining errors during machining, and enables even an inexperienced operator to easily and reliably diagnose the cause of machining errors. [Means for solving the problem]

[0007] In order to achieve the above object, the invention described in claim 1 of the present invention is a diagnostic device for diagnosing the cause of machining errors occurring in each machining of a plurality of workpieces having the same shape, the diagnostic device comprising: an error transition recording unit in which multiple types of error transition information in which the time transition of the machining error differs as the machining is repeated is recorded; an error transition input unit for selecting one or multiple pieces of error transition information from the multiple types of error transition information; an error cause recording unit in which multiple types of the causes are recorded in correspondence with the error transition information; a cause diagnosis unit for referring to the error cause recording unit and identifying the cause based on the error transition information selected by the error transition input unit; and a display unit for displaying the cause identified by the cause diagnosis unit. The invention described in claim 2 is characterized in that, in the invention described in claim 1, a machining part input unit is provided for inputting machining part information which is information relating to identifying the machining error in the workpiece, and a machining condition input unit is provided for inputting machining condition information which is information relating to the machining of the workpiece, and the cause is associated with the machining part information and the machining condition information, and the cause diagnosis unit refers to the error cause recording unit and identifies the cause based on the error trend information selected by the error trend input unit, the machining part information input by the machining part input unit, and the machining condition information input by the machining condition input unit. The invention described in claim 3 is characterized in that, in the invention described in claim 2, it is connected to an NC device, and at least one of the machining part information and the machining condition information can be selected and input from data recorded in the NC device. The invention described in claim 4 is the invention described in any one of claims 1 to 3, characterized in that the error trend input unit is capable of inputting an actual measured value of the time trend of the machining error, and the error trend input unit calculates at least one of the following features related to the selection of the error trend information based on the input actual measured value of the time trend: the machining error from a target value in the first machined workpiece, the absolute value of the displacement width of the machining error occurring between the first machined workpiece and the last machined workpiece, the maximum value of the difference between the machining error in the previous machining and the machining error in the current machining, the error from a straight-line approximation value, and the error from a first-order lag approximation value, and selects the error trend information based on the calculated feature value. In addition, the time transition of the machining error caused by repeating machining in the present invention is not limited to the correlation of the machining error caused by each machining with the machining time, but includes the correlation of the machining error caused by each machining with the number of machining operations, and the correlation of the machining error caused by each machining with the number of machining operations. In addition, the machining error in the invention described in claim 1 includes, in addition to the error caused in the workpiece, for example, the error of the tool length offset measured by a tool sensor and the error of the machining origin of the workpiece measured by a probe or the like. Effect of the Invention

[0008] According to the present invention, there are provided an error transition recording section in which multiple types of error transition information with different time transitions of machining errors accompanying repeated machining are recorded, an error transition input section for selecting one or more error transition information from the multiple types of error transition information, an error cause recording section in which multiple types of causes are recorded in association with the error transition information, a cause diagnosis section for identifying a cause based on the error transition information selected by the error transition input section by referring to the error cause recording section, and a display section for displaying the cause identified by the cause diagnosis section. Therefore, an operator can grasp the cause of a machining error simply by selecting error transition information similar to the current machining situation. Therefore, even an inexperienced operator can easily and reliably diagnose the cause of a machining error. In addition, since there is no need to collect machine data that may be a cause of a machining error during machining, the cost of the diagnosis device can be reduced. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing a configuration of a diagnostic device. [Diagram 2] FIG. 2 is an explanatory diagram showing a shape diagram of a workpiece. [Diagram 3] 10 is an explanatory diagram showing the transition over time of a plurality of types of machining errors recorded in an error transition recording unit; FIG. [Figure 4] FIG. 4 is an explanatory diagram showing a display mode on a display unit of the diagnostic device. [Diagram 5] 11A and 11B are explanatory diagrams showing modified examples of the display mode on the display unit. [Figure 6] FIG. 1 is an explanatory diagram showing a method for machining a workpiece. [Figure 7] 1 is a table in which causes of machining errors are associated with machining portions, tool types, and displacement data. [Figure 8] FIG. 11 is an explanatory diagram showing a change over time in a machining error obtained in actual machining. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A diagnostic device according to an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the diagnostic device 1. FIG. 2 is an explanatory diagram showing a shape diagram of the workpiece 11. FIG. 3 is an explanatory diagram showing the time transition of multiple types of machining errors recorded in the error transition recording unit 2. FIG. 4 is an explanatory diagram showing the display mode on the display unit 7 of the diagnostic device 1. FIG. 5 is an explanatory diagram showing a modified example of the display mode on the display unit 7. FIG. 6 is an explanatory diagram showing a machining method for the workpiece 11. FIG. 7 is a table in which causes of machining errors are associated with machining parts, tool types, and displacement data. FIG. 8 is an explanatory diagram showing the time transition of machining errors obtained in actual machining.

[0011] First, the workpiece in this embodiment is workpiece 11 shown in Fig. 2. In addition, the machining error in this embodiment is an error from a target value Yo of distance L in the Y-axis direction between holes 12 and 13, when the target value Yo is the distance L between holes 12 and 13, which are drilled in the upper surface of workpiece 11. Note that the X-axis direction in Fig. 2 is the left-right direction, the Y-axis direction is the front-back direction, and the Z-axis direction is the up-down direction.

[0012] Moreover, holes 12 and 13 are machined as follows. First, drill 31 installed in NC device 8 is moved to and positioned at the coordinates of the X-axis and Y-axis corresponding to hole 12. Then, drill 31 is fed in the Z-axis direction to cut hole 12. Next, drill 31 is moved to and positioned at the coordinates of the X-axis and Y-axis corresponding to hole 13, and then fed in the Z-axis direction to cut hole 13. Then, when machining of holes 12 and 13 in one workpiece 11 is completed, a new workpiece 11 is replaced and the same machining is repeated.

[0013] When the above-mentioned machining process for forming holes 12 and 13 in workpiece 11 is continued repeatedly, machining errors naturally occur with each machining process. Displacement data, which is the time transition of machining errors accompanying such repeated machining, is shown in graphs such as those shown in Figs. 3A to 3F. The dashed line in the center of each graph indicates the target value Yo of distance L. Also, δ in each graph indicates the machining error from the target value Yo in the first machined workpiece 11 (hereinafter referred to as the initial product). Furthermore, ΔY in each graph indicates the displacement width of the machining error occurring from the initial product to the last machined workpiece 11 (hereinafter referred to as the final product), that is, the difference between the smallest machining error and the largest machining error.

[0014] Here, the characteristics of the change over time in the machining error of the workpiece 11 will be described. Displacement data, which is the time transition of machining error, has various forms as shown in Figures 3A to 3F. Displacement data A is a form in which the machining error δ of the initial product is large and the displacement width ΔY is small. Displacement data B, C, D, and E are forms in which the machining error δ of the initial product is small but the displacement width ΔY is large. Furthermore, displacement data F is a form in which the machining error δ of the initial product is small and the displacement width ΔY is also small, that is, a form in which the machining error is small overall.

[0015] In addition, the displacement data B, C, D, and E can be classified according to the characteristics related to the time-dependent change in the machining error and the displacement width ΔY. The displacement data B is a type in which the machining error at each time changes irregularly in a short time. The displacement data C is a type in which the displacement width ΔY changes with time, and in this case, increases. The displacement data D is a type in which the displacement width ΔY changes significantly at the beginning of machining, and then the machining error at each time stabilizes in the state after the change, and eventually the displacement width ΔY also stabilizes. The displacement data E is a type in which the machining error at each time continues to change without stabilizing from the start to the end of machining, although not in as short a time as the displacement data B.

[0016] Furthermore, a method for selecting similar displacement data from the displacement data obtained in actual machining will be described. 8 is obtained as a result of repeatedly continuing the above-mentioned machining to form holes 12 and 13 in workpiece 11, displacement data B is selected as the displacement data that shows the closest characteristics among the displacement data A to F. In other words, displacement data B can be selected because the machining error δa of the initial product is small, but the displacement width ΔYa from the initial product to the final product is large, and further the machining error for each product changes irregularly in a short period of time.

[0017] More specifically, the feature quantities are the machining error δ of the first product, the absolute value of the displacement width ΔY, the maximum value of the difference between the machining error in the previous machining and the machining error in the current machining, the error from the linear approximation value, and the error from the first-order lag approximation value. If the machining error δ of the first product exceeds a predetermined judgment value, the displacement data A is selected. If the absolute value of the displacement width ΔY exceeds a predetermined judgment value and the maximum value of the difference between the machining errors in the previous machining and the current machining also exceeds a predetermined judgment value, the displacement data B is selected. If the absolute value of the displacement width ΔY exceeds the judgment value but the error from the linear approximation value is small, the displacement data C is selected. If the absolute value of the displacement width ΔY exceeds the judgment value but the error from the first-order lag approximation value is small, the displacement data D is selected. If the absolute value of the displacement width ΔY exceeds the judgment value but the maximum value of the difference between the machining errors in the previous machining and the current machining is smaller than the judgment value and the error from the linear approximation value and the error from the first-order lag approximation value are large, the displacement data E is selected. Furthermore, if both the machining error δ and the displacement width ΔY of the initial product are smaller than their respective judgment values, the displacement data F is selected. Therefore, when the displacement data shown in FIG. 8 is obtained, the absolute value of the displacement width ΔY exceeds the judgment value, and the maximum value of the difference between the machining error in the previous and current processes also exceeds the judgment value, so that the displacement data B is selected. In this embodiment, the worker selects similar displacement data as described later. However, as described as a modified example, it is also possible to configure the diagnosis device to automatically select similar displacement data.

[0018] Based on the above, the diagnosis of the cause of the machining error by the diagnosis device 1 will be described. The diagnostic device 1 includes an error transition recording section 2 in which the displacement data A to F are recorded, and a display section 7 that displays the displacement data A to F. The diagnostic device 1 also includes an error transition input section 3 for selecting the displacement data displayed on the display section 7, a machining part input section 4 for inputting the machining part together with the shape diagram of the workpiece 11, and a machining condition input section 5 for inputting machining conditions such as the spindle rotation speed during machining, the spindle feed rate, and the type of tool used in machining. The diagnostic device 1 also includes an error cause recording section 9 that records the causes of machining errors. In the error cause recording section 9, a plurality of types of causes that are assumed in advance as the causes of machining errors are recorded in association with the machining part, the type of tool, and the displacement data, as shown in the table in FIG. 7. In addition, the diagnostic device 1 includes a cause diagnosing section 6 that diagnoses the cause of machining errors from the information inputted in the error transition input section 3, the machining part input section 4, and the machining condition input section 5, and the information recorded in the error cause recording section 9.

[0019] The display unit 7 displays the displacement data and the like in a manner as shown in Fig. 4. That is, the display unit 7 is provided with an error part display unit 22 that displays the shape diagram and machining part of the workpiece 11 and also displays the error part where a machining error occurs, an error transition display unit 23 that displays the displacement data A to F recorded in the error transition recording unit 2, and a machining condition display unit 24 that displays the machining conditions including the type of tool, etc. The display unit 7 is also provided with a diagnosis start button 25 for starting the diagnosis of the cause of the machining error after inputting the machining part and machining conditions and selecting the displacement data, and an error cause display unit 26 that displays the diagnosis result by the cause diagnosing unit 6, i.e., the cause of the machining error identified by the cause diagnosing unit 6.

[0020] A specific example of the diagnosis of the cause of the machining error by the above-mentioned diagnosis device 1 in the case where the displacement data shown in Fig. 8 is obtained in the current machining will be described. First, the operator inputs a shape diagram of the workpiece 11 through the machining part input unit 4 and selects the holes 12 and 13. Then, the error part display unit 22 displays the distance in the X-axis direction and the distance in the Y-axis direction as the distance between the holes 12 and 13 where the machining error occurs. Then, the operator inputs through the machining part input unit 4 that the machining error to be diagnosed this time is the machining error related to the distance L in the Y-axis direction. Note that the diagnosis device 1 and the NC device 8 may be connected, and the input of the shape diagram of the workpiece 11 may be selected from the shape diagrams of the workpiece stored in advance in the NC device 8.

[0021] Next, the operator uses the error transition input unit 3 to select the displacement data B having characteristics closest to those of the displacement data shown in FIG. 8 from among the displacement data A to F displayed on the error transition display unit 23. Furthermore, the operator uses the machining condition input unit 5 to input the spindle rotation speed during machining, the spindle feed speed, and the type of tool used in machining. The machining conditions input at this time are displayed on the machining condition display unit 24. It should be noted that the input of machining conditions may also be selected from information on the machining program stored in advance in the NC unit 8 by connecting the diagnosis device 1 and the NC unit 8.

[0022] Upon completion of the above input, the operator operates diagnosis start button 25 in display unit 7. Then, cause diagnosis unit 6 refers to the table shown in Fig. 7 and identifies the cause of the error as "tool runout" from the information input by machining portion input unit 4, the displacement data selected by error transition input unit 3, and the information input by machining condition input unit 5, and displays "tool runout" in error cause display unit 26 as the result of error diagnosis. Therefore, by referring to error cause display unit 26, the operator can determine that the cause of the machining error is "tool runout."

[0023] According to the diagnosis device 1 having the above-mentioned configuration, there are provided the error transition recording section 2 in which a plurality of types of displacement data A to F are recorded, the error transition input section 3 for selecting one displacement data from the plurality of types of displacement data A to F, the error cause recording section 9 in which a plurality of types of causes are recorded in association with the displacement data A to F, the cause diagnosing section 6 for identifying the cause based on the displacement data selected by the error transition input section 3 with reference to the error cause recording section 9, and the display section 7 for displaying the cause identified by the cause diagnosing section 6, so that the operator can grasp the cause of the machining error simply by selecting the displacement data similar to the current machining situation. Therefore, even an inexperienced operator can easily and reliably diagnose the cause of the machining error. In addition, since there is no need to collect machine data that may be a cause of the machining error during machining, the diagnosis device 1 can be manufactured at a low cost.

[0024] The diagnosis device 1 is provided with a machining part input section 4 for inputting machining part information, which is information related to the specification of machining errors, including a shape diagram and machining part of the workpiece 11, and a machining condition input section 5 for inputting machining condition information, which is information related to the machining of the workpiece 11, including the spindle rotation speed during machining, the feed rate of the spindle, and the type of tool used in machining, and the cause of the machining error is associated with the machining part and the type of tool, and the cause diagnosis section 6 refers to the error cause recording section 9 and specifies the cause based on the information input by the machining part input section 4, the displacement data selected by the error transition input section 3, and the information input by the machining condition input section 5. Therefore, the cause of the machining error can be diagnosed more accurately.

[0025] Furthermore, by connecting to the NC device 8, the input of the shape diagram of the workpiece 11 may be selected from the shape diagrams of the workpiece pre-stored in the NC device 8, and the input of the machining conditions may be selected from the information of the machining program pre-stored in the NC device 8. By connecting to the NC device 8 in this way, the cause of the machining error can be diagnosed more easily.

[0026] The diagnostic device according to the present invention is not limited to the above-described embodiment, and the overall configuration of the diagnostic device as well as the configuration related to the diagnosis of the cause of the processing error can be appropriately modified as necessary without departing from the spirit of the present invention.

[0027] For example, in the above embodiment, the display unit 7 is provided with the error transition display unit 23 that displays the displacement data A to F, and is configured so that the operator can select similar displacement data. However, instead of such error transition display unit 23, a dimensional error transition display unit 27 and an actual measurement data display unit 28 as shown in FIG. 5 may be provided, and when the operator inputs a dimensional error, the displacement data of the machining error that has occurred this time is displayed on the actual measurement data display unit 28, and similar displacement data is automatically selected in the diagnosis device 1, and ultimately the cause of the machining error is displayed on the error cause display unit 26.

[0028] In the modified example shown in FIG. 5, after inputting the machining part input unit 4, the operator measures the dimensions of the workpiece 11 that has actually been machined using the error transition input unit 3, and inputs the machining time and the dimensions or machining errors. This input value is displayed on the dimension error transition display unit 27. In addition, the displacement data of the machining error corresponding to the input value, i.e., the displacement data of the machining error that has occurred this time, is displayed on the actual measurement data display unit 28. Then, when the operator operates the diagnosis start button 25, the error transition input unit 3 calculates the machining error δ of the initial product, the absolute value of the displacement width ΔY, the maximum value of the difference between the machining error in the previous machining and the machining error in the current machining, the error from the linear approximation value, and the error from the first-order lag approximation value as feature values ​​based on the input values. In addition, based on the calculated feature values, similar displacement data is selected from the displacement data A to F recorded in the error cause recording unit 9 by the method described as the method for selecting displacement data in the above embodiment. Then, the cause diagnosis unit 6 identifies the cause of the error from the selected displacement data and the information input by the processing area input unit 4 and the processing condition input unit 5, and displays the identified cause of the error on the error cause display unit 26.

[0029] In the diagnostic device of the modified example having the above-mentioned configuration, as in the diagnostic device 1 of the above-mentioned embodiment, since it is not necessary to collect machine data that may cause machining errors during machining, the cost of the diagnostic device can be reduced. In addition, the error transition input unit 3 can input the actual measurement value of the time transition of the machining error, and the error transition input unit 3 calculates the machining error δ of the initial product, the absolute value of the displacement width ΔY, the maximum value of the difference between the machining error in the previous machining and the machining error in the current machining, the error from the linear approximation value, and the error from the first-order lag approximation value, which are characteristic quantities related to the selection of the displacement data, based on the input actual measurement value of the time transition, and automatically selects the displacement data based on the calculated characteristic quantities, so that even an inexperienced operator can easily and reliably diagnose the cause of the machining error.

[0030] As another modification, for example, one displacement data is selected in the above embodiment and modification, but multiple displacement data may be selected and multiple types of machining error causes corresponding to each displacement data may be displayed on the display unit. Also, how the time transition of the machining error and the cause of the machining error are specifically associated in the error cause recording unit can be changed, and there is no problem even if multiple types of machining error causes are associated with one displacement data.

[0031] Furthermore, in the above embodiment and modified example, the machining part input section and the machining condition input section are provided, but it is also possible to provide only one of them, or to provide neither. In other words, by selecting the time transition of the machining error, it is also possible to configure it so that the causes of multiple types of machining errors are displayed in correspondence with each machining part information, or in correspondence with each machining condition information. It goes without saying that the design of how the causes of machining errors, machining parts, machining conditions, etc. are specifically displayed on the display section, as well as the display mode and layout, can be changed.

[0032] In addition, the time transition of the machining error accompanying the repetition of machining in the present invention is not limited to the machining error occurring with each machining associated with the machining time, but includes the machining error occurring with each machining associated with the number of machining operations, or the machining error occurring with each machining associated with the number of pieces machined. Furthermore, the machining error in the present invention includes, in addition to the error occurring in the workpiece in the above embodiment, for example, the error of the tool length offset measured by a tool sensor and the error of the machining origin of the workpiece measured by a probe or the like. [Explanation of symbols]

[0033] Reference Signs List 1... Diagnosis device, 2... Error trend recording section, 3... Error trend input section, 4... Machining part input section, 5... Machining condition input section, 6... Cause diagnosis section, 7... Display section, 8... NC device, 9... Error cause recording section, 11... Workpiece.

Claims

1. A diagnostic device for diagnosing a cause of a machining error occurring in each machining operation of a plurality of workpieces having the same shape, comprising: an error transition recording unit in which multiple types of error transition information, which show different transitions of the processing error over time that occur when the processing is repeated, are recorded; an error transition input unit for selecting one or more pieces of error transition information from the plurality of types of error transition information; an error cause recording unit in which a plurality of types of the causes are recorded in association with the error transition information; a cause diagnosing unit that refers to the error cause recording unit and identifies the cause based on the error transition information selected by the error transition input unit; a display unit that displays the cause identified by the cause diagnosing unit.

2. a machining portion input unit for inputting machining portion information which is information relating to the identification of the machining error in the workpiece; a processing condition input unit for inputting processing condition information, which is information related to processing of the workpiece, The cause is also associated with the machining portion information and the machining condition information, The diagnostic device according to claim 1, characterized in that the cause diagnosing unit refers to the error cause recording unit, and identifies the cause based on the error transition information selected by the error transition input unit, the machined part information input by the machined part input unit, and the machining condition information input by the machining condition input unit.

3. It is connected to an NC device.

3. The diagnostic device according to claim 2, wherein at least one of the machined portion information and the machining condition information can be selected and input from data recorded in the NC device.

4. The error transition input unit can input an actual measurement value of the time transition of the processing error, The diagnostic device according to any one of claims 1 to 3, characterized in that the error transition input unit calculates at least one of the following features related to the selection of the error transition information based on the input actual measurement value of the time transition: the machining error from a target value in the first machined workpiece, the absolute value of the displacement width of the machining error occurring between the first machined workpiece and the last machined workpiece, the maximum value of the difference between the machining error in the previous machining and the machining error in the current machining, the error from a straight-line approximation value, and the error from a first-order lag approximation value, and selects the error transition information based on the calculated feature values.

Images