On-machine measurement technology application method for three-axis machine tool

Abstract

The invention discloses an application method of an on-machine measurement technology for a three-axis machine tool. The method comprises the following steps: 1) supporting incoming material detection, calculating a Z-direction height difference, and judging whether an incoming material detection requirement is met or not; the device has the advantages of being simple in structure, convenient to operate, capable of supporting edge-finding centering detection including rectangular centering, L-shaped centering, U-shaped centering and circular centering, avoiding manual metering centering, capable of supporting measurement compensation machining detection including plane measurement compensation, circular compensation and two-point distance compensation, avoiding secondary clamping of workpieces and improving machining efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of machining, and relates to the in-machine measurement technology of a three-axis machine tool. Specifically, it is an application method of an in-machine measurement technology that combines measurement and machining compensation. Background Art

[0002] With the continuous upgrading of manufacturing technology, higher requirements are also put forward for the accuracy and production efficiency of products. In order to solve problems such as dimensional deviation deformation, secondary clamping, and origin error in product processing, certain detection means must be introduced. There is a large amount of manual participation in processes such as workpiece alignment, incoming material inspection, process inspection, and first-piece inspection. There is even a situation where operators modify the machining program on-site, directly increasing the product processing cost and personnel burden. Especially in the process of automated production, the production continuity is greatly reduced.

[0003] In-machine measurement technology is a technology that realizes automatic detection of workpiece machining quality on a machining center. Using this technology, part alignment, deformation compensation of workpiece contours and surfaces, in-machine detection during the machining process, etc. can be carried out to improve machining efficiency, reduce error accumulation, and improve machining quality.

[0004] In current in-machine measurement and detection applications, the manual participation degree is high. It is necessary to manually write detection programs on the machine tool, and it is also necessary to integrate NC programs according to the machining process flow, which requires a very high technical level for operators; before machining, it is necessary to first find the workpiece center on a coordinate measuring machine. If the machined product is unqualified, it is necessary to redo or modify the machining path for supplementary machining, resulting in a long auxiliary machining time. These problems often interrupt machining, cannot guarantee production continuity, and affect the further improvement of machining efficiency. Moreover, the compatibility between devices will also cause certain interference to machining production. Summary of the Invention

[0005] The object of the present invention is to creatively apply the in-machine measurement technology to the automated processing production process in view of the problems in the above-mentioned existing technologies, and provide a method for incoming material detection, automatic centering and alignment detection, and workpiece plane (inclined plane) measurement and supplementary machining of a three-axis machine tool based on the in-machine measurement technology. Through simple interactive operations, a measurement path is directly generated in the CAM software, avoiding operations on the machine tool. The incoming material detection of the workpiece and the alignment of the workpiece position on the machine tool are realized through various strategies; the plane measurement and supplementary machining, circular supplementary machining (holes, shafts), and two-point distance supplementary machining (bosses and grooves) of the machined path are realized, the detected deviation is compensated into the tool parameters, and the machining program is called to perform conditional loop supplementary machining on the workpiece; it supports the burr judgment and out-of-tolerance judgment when detecting contact and the corresponding operations according to the judgment results, and can directly output the NC program for on-machine operation. Automatically judge whether the Z-direction height difference of the workpiece exceeds the tolerance, automatically judge whether to compensate for multiple workpiece origins according to the detection results, and apply it to the subsequent measurement or machining path. Eliminate the manual participation in the on-machine alignment process and reduce the auxiliary time.

[0006] In order to achieve the above object, the technical solution adopted by the present invention includes the following steps.

[0007] 1. Create an incoming material detection path 1) Establish an incoming material detection path according to the features to be machined of the workpiece, create measurement points in the path, and the number of measurement points is n , ; 2) Set the upper limit and the lower limit of the deviation detection threshold, generate the path and output the NC program; 3) After the machine tool performs the detection, calculate the Z-direction height difference according to the theoretical measurement point and the actual measurement point; 4) If , the incoming material detection is qualified, and subsequent operations are performed; otherwise, an alarm is given and the program is stopped.

[0008] 2. Create a centering detection path 1) Select the centering deviation detection path type (L-type centering, U-type centering, rectangular centering, circular centering) according to the features to be measured of the workpiece, create a centering detection path, and create measurement points in the path; L-type centering: By detecting two mutually perpendicular sides in the plane of the workpiece, the center coordinates of the workpiece are determined. The side parallel to the X-axis determines the center Y coordinate, and the side parallel to the Y-axis determines the center X coordinate; 3 measurement points need to be created, 2 measurement points on the long side determine the deflection angle, and 1 measurement point on the short side; adding a Z-direction measurement point is supported to determine the center Z coordinate; U-shaped centering: By detecting three edges distributed in a U-shape within the plane of the workpiece, the central coordinates of the workpiece are determined. It is required that two of the edges are parallel, and one of the edges is projected onto the opposite edge, with the projection having a common part with the opposite edge; the edge parallel to the X-axis determines the central Y coordinate, and the edge parallel to the Y-axis determines the central X coordinate; 4 measurement points need to be created, 1 measurement point for each of the two parallel edges, and 2 measurement points for a single edge to determine the deflection angle; adding Z-direction measurement points is supported to determine the central Z coordinate; Rectangular centering: By detecting the edges distributed in a rectangle within the plane of the workpiece, the central coordinates of the workpiece are determined. As long as the selected detection edges satisfy that their extension lines can form a closed rectangle, it is required that one of the selected edges is projected onto its opposite edge, and this projection has a common part with the opposite edge; the edge parallel to the X-axis determines the central Y coordinate, and the edge parallel to the Y-axis determines the central X coordinate; 5 measurement points need to be created, 2 measurement points for the long side to determine the deflection angle, and 1 measurement point for each of the remaining 3 edges; adding Z-direction measurement points is supported to determine the central Z coordinate; Circular three-point centering: By detecting the cross-sectional circle on a circular hole or cylinder within the plane of the workpiece, the central coordinates of the workpiece are determined, and the central coordinates of the workpiece are fitted according to the measurement points; 3 measurement points need to be created, evenly distributed at 3 points on the circumference; adding Z-direction measurement points is supported; Circular four-point centering: By detecting the cross-sectional circle on a circular hole or cylinder within the plane of the workpiece, the central coordinates of the workpiece are determined, and the central coordinates of the workpiece are fitted according to the measurement points; 4 measurement points need to be created, with 1 measurement point in the positive and negative directions of the machining coordinate axis on the circumference; adding Z-direction measurement points is supported; All centering detection path types support adding machining allowances to any detection edge and compensating the workpiece origin to the machine tool machining coordinate system; 2) Set the centering compensation threshold , generate the path and output the NC program; 3) After the machine tool performs detection, calculate the center deviation based on the center position of the theoretical measurement points and the center position of the actual measurement points ; 4 If , , are all satisfied simultaneously, the origin compensation of the machine tool machining coordinate system is automatically performed; otherwise, the program stops; 5) For the origin compensation of the machine tool machining coordinate system, first calculate the compensation value of the workpiece origin: ; then calculate the actual value of compensating the workpiece origin: , and replace the original origin value of the machine tool machining coordinate system with the sum of the actual value and the compensation value; 6) When creating the centering detection path, select the feature of arranging measurement points for the workpiece model, and add the current machining allowance of the workpiece to meet the centering and alignment of the workpiece.

[0009] 3. Create the compensation machining path 1) In the workpiece model, a compensation machining path is established according to the machining features to be processed of the workpiece, and measurement points are created in the path; 2) Set the upper limit of the machining compensation threshold and the lower limit , generate the path and output the numerical control program; 3) After the workpiece is machined, perform detection on the machine tool. According to the theoretical data and the actually measured data, calculate the single-point deviation in the Z direction of the plane , and calculate the deviation by taking the difference ; 4) If it does not meet , then stop the program and give an alarm; otherwise, calculate the compensation deviation , compensate the deviation value to the tool parameters, and call the additional machining program; 5) After completing the additional machining, loop through steps 3) and 4) until any additional machining termination condition (number of cycles, machining compensation threshold) is met, then jump out of the additional machining loop and execute the alarm or other specified commands; In step 1) of the compensation machining path, the compensation machining path includes plane measurement compensation, two-point distance compensation, and circular compensation: Plane measurement compensation determines whether the plane machining is qualified by measuring the size of the plane relative to the theoretical plane; two-point distance compensation determines whether the machining is qualified by measuring the distance between two points on the workpiece; circular compensation determines whether the machining is qualified by creating three measurement points on the cross-section of the cylindrical or circular hole feature of the workpiece and comparing the deviation between the theoretical value and the measured value; The above three compensations all support cyclic detection, support setting commands to be executed after exceeding the compensation cycle times, and end the machining path with ineffective compensation.

[0010] In step 4) of the compensation machining path, the compensation deviation is calculated according to the selected machining reference. If the bottom surface of the workpiece or the fixture surface, etc. is used as the reference, the calculated compensation deviation is: ; If the machined surface of the workpiece is used as the reference, the calculated compensation deviation is: .

[0011] Compared with the prior art, the present invention has the following advantages: Advantage 1: The present invention supports incoming material inspection, supports detection of the clamping deflection angle of the workpiece, and determines whether the Z-direction height difference exceeds the tolerance; Advantage 2: The present invention combines the in-machine measurement technology with automated production, realizes the edge finding and centering detection of the workpiece, supports the rectangular centering, L-shaped centering, U-shaped centering, and circular centering of the workpiece, and compensates the workpiece origin according to the centering result; Advantage 3: The present invention supports the creation of measurement compensation machining paths and the NC program output function, realizes plane measurement compensation, circular compensation, and two-point distance compensation for the machined paths, adds the compensation deviation detected by measurement to the corresponding tool radius or tool length, calls the machining program, and performs conditional loop supplementary machining; Advantage 4: The present invention reduces the degree of manual participation, transfers all the work to the programming end, does not interrupt the operation of the machine tool, and improves the utilization rate of the machine tool and the product machining efficiency. Description of the Drawings

[0012] Figure 1 The application flow chart of the present invention based on in-machine measurement technology; Figure 2 Schematic diagram for selecting the detection path type; Figure 3 Schematic diagram of the measurement points for in-coming material inspection; Figure 4 Schematic diagram of the measurement points for center finding and alignment; Figure 5 Schematic diagram of the measurement points for measurement supplementary machining. Detailed Implementation Manner

[0013] The following further elaborates on the present invention in conjunction with the drawings. For the overall flow chart, see Figure 1 .

[0014] 1. See Figure 2 , and add the detection path type.

[0015] 2. See Figure 3 and create an in-coming material inspection path: 1) Select the right side of the rectangular part as the workpiece feature surface for in-coming material inspection, create appropriate measurement points on the feature surface, and set the upper limit and the lower limit of the deviation detection threshold, generate the path and output the NC program; 2) After the machine tool performs the detection, calculate the Z-direction height difference according to the theoretical measurement points and the actual measurement points; 3) If , the in-coming material inspection is qualified, and subsequent operations are performed; otherwise, an alarm is given and the program is stopped.

[0016] 3. See Figure 4 and create a center finding and alignment path: 1) Select the rectangular center finding in the center finding deviation detection path types (L-type center finding, U-type center finding, rectangular center finding, circular center finding) to create the center finding and alignment path; 2) Select the four sides of the rectangle to determine the center coordinates of the workpiece, create 5 measurement points, 2 measurement points on the long side to determine the deflection angle, and 1 measurement point on each of the remaining 3 sides; 3) Set the center finding and alignment compensation threshold , generate the path and output the NC program; 4) After the machine tool performs the detection, calculate the center deviation based on the center position of the theoretical measurement point and the center position of the actual measurement point. ; 5) If , , are all satisfied simultaneously, perform the origin compensation of the machine tool processing coordinate system; otherwise, stop the program. 6) For the origin compensation of the machine tool processing coordinate system, first calculate the compensation value of the workpiece origin: ; then calculate the actual value of the compensated workpiece origin: , and replace the original origin value of the machine tool processing coordinate system with the sum of the actual value and the compensation value.

[0017] 4. Refer to Figure 5 to create the compensated machining path: 1) Select the plane measurement compensation type according to the machining path. 2) Set the upper limit and the lower limit of the machining compensation threshold, calculate the single-point deviation in the Z direction of the plane based on the workpiece bottom surface , and then calculate the deviation by taking the difference. The deviation is ; 3) Determine whether the deviation exceeds the set threshold. If it does not meet , stop the program and alarm; otherwise, execute the additional machining program. 4) Obtain the compensation deviation through deviation calculation , compensate the deviation value to the tool parameters, and perform the compensated machining of the machining path. After the machining is completed, perform the machining deviation detection again. If the machining standard is reached, jump out of the compensated machining loop program; if the compensated machining loop count or the machining compensation threshold is reached, alarm and terminate the program.

Claims

1. A method for applying in-machine measurement technology to a three-axis machine tool, characterized in that It includes the following steps: 1) In the workpiece model, establish an incoming material inspection path according to the features to be machined on the workpiece, create measurement points in the path, and the number of measurement points is n. , set the upper limit of the deviation detection threshold , lower limit , generate the path and output the numerical control program; After the machine tool performs detection, calculate the Z-direction height difference based on the theoretical measurement point and the actual measurement point ; If , the incoming material inspection is qualified, and subsequent operations are performed; otherwise, an alarm is given and the program is stopped. 2) In the workpiece model, establish a centering detection path according to the features to be measured of the workpiece, create measurement points in the path, and set the centering compensation threshold , generate the path and output the numerical control program; After the machine tool performs detection, calculate the center deviation based on the center position of the theoretical measurement point and the center position of the actual measurement point , if , , If both are satisfied at the same time, automatically perform the origin compensation of the machine tool processing coordinate system; otherwise, stop the program; For the origin compensation of the machine tool processing coordinate system, first calculate the compensation value of the workpiece origin: , then calculate the actual value of the compensated workpiece origin: , and replace the original origin value of the machine tool processing coordinate system with the sum of the actual value and the compensation value; 3) In the workpiece model, establish a measurement compensation path according to the features to be machined on the workpiece, create measurement points in the path, and set the upper limit of the machining compensation threshold and the lower limit , generate the path and output the numerical control program; After the workpiece is processed, the machine tool performs detection, and calculates the single-point deviation in the Z direction of the plane according to the theoretical data and the actually measured data , and calculates the deviation by taking the difference ; If the condition is not met , stop the program and give an alarm; otherwise, calculate the compensation deviation , compensate the deviation value to the tool parameters, call the additional machining program, and perform the machining deviation detection again. If the compensation threshold or the number of machining times is reached, jump out of the additional machining loop and execute the alarm or other specified commands; Among them, the compensation deviation is calculated according to the selection of the machining reference. If the bottom surface of the workpiece or the fixture surface, etc. is used as the reference, the compensation deviation is calculated ; If the machined surface of the workpiece is used as the reference, calculate the compensation deviation: .

2. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: In step 2), L-shaped centering is supported for centering deviation detection. By detecting two mutually perpendicular sides within the workpiece surface, the center coordinates of the workpiece are determined. For L-shaped centering, 3 measurement points need to be created, 2 measurement points on the long side and 1 measurement point on the short side; 1) The side parallel to the X-axis determines the center Y coordinate, and the side parallel to the Y-axis determines the center X coordinate; 2) The deflection angle is determined by the 2 measurement points on the long side; 3) Adding a Z-direction measurement point is supported to determine the center Z coordinate; 4) Adding machining allowance to any detected side and compensating the workpiece origin to the machine tool machining coordinate system are supported.

3. The application method of in-machine measurement technology for a three-axis machine tool according to claim 1, wherein: In step 2), U-shaped centering is supported for centering deviation detection. By detecting three sides distributed in a U-shape within the workpiece surface, the center coordinates of the workpiece are determined. For U-shaped centering, 4 measurement points need to be created, 1 measurement point on each of the two parallel sides and 2 measurement points on the single side; 1) It is required that two of the sides are parallel, project one of the sides onto the opposite side, and the projection has a common part with the opposite side; 2) The side parallel to the X-axis determines the center Y coordinate, and the side parallel to the Y-axis determines the center X coordinate; 3) The deflection angle is determined by the 2 measurement points on the single side; 4) Adding a Z-direction measurement point is supported to determine the center Z coordinate; 5) Adding machining allowance to any detected side and compensating the workpiece origin to the machine tool machining coordinate system are supported.

4. The application method of in-machine measurement technology for a three-axis machine tool according to claim 1, characterized in that: In step 2), rectangular centering is supported for centering deviation detection. By detecting the sides distributed in a rectangle within the workpiece surface, the center coordinates of the workpiece are determined. For rectangular centering, 5 measurement points need to be created, 2 measurement points on the long side and 1 measurement point on each of the remaining 3 sides; 1) As long as the selected detected sides satisfy that their extension lines can form a closed rectangle, it is required to project one of the selected sides onto its opposite side, and this projection has a common part with the opposite side; 2) The side parallel to the X-axis determines the center Y coordinate, and the side parallel to the Y-axis determines the center X coordinate; 3) The deflection angle is determined by the 2 measurement points on the long side; 4) Adding a Z-direction measurement point is supported to determine the center Z coordinate; 5) Adding machining allowance to any detected side and compensating the workpiece origin to the machine tool machining coordinate system are supported.

5. The application method of in-machine measurement technology for a three-axis machine tool according to claim 1, characterized in that: In step 2), circular three-point centering is supported for centering deviation detection. By detecting the cross-sectional circle on a round hole or cylinder within the workpiece surface, the center coordinates of the workpiece are determined. For circular three-point centering, 3 measurement points need to be created, evenly distributed at 3 points on the circumference; 1) Fit the workpiece center coordinates according to the measurement points; 2) Adding a Z-direction measurement point is supported; 3) Adding machining allowance to the detected side and compensating the workpiece origin to the machine tool machining coordinate system are supported.

6. The method for applying in-machine measurement technology for a three-axis machine tool according to claim 1, wherein: In step 2), circular four-point centering is supported for centering deviation detection. By detecting the cross-sectional circle on a round hole or cylinder within the workpiece surface, the center coordinates of the workpiece are determined. For circular four-point centering, 4 measurement points need to be created, 1 measurement point in the positive and negative directions of the machining coordinate axes on the circumference; 1) Fit the workpiece center coordinates according to the measurement points; 2) Adding a Z-direction measurement point is supported; 3) Adding machining allowance to the detected side and compensating the workpiece origin to the machine tool machining coordinate system are supported.

7. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, wherein: In step 3), plane measurement compensation is supported. Whether the plane machining is qualified is judged by measuring the size of the plane relative to the theoretical plane; 1) Circular probing is supported; 2) Support setting an instruction to be executed after exceeding the compensation loop count to end the machining path with invalid compensation.

8. The application method of in-machine measurement technology for a three-axis machine tool according to claim 1, characterized in that: In step 3), two-point distance compensation is supported, and the machining is judged to be qualified by measuring the distance between two points on the workpiece. 1) Support loop detection; 2) Support setting an instruction to be executed after exceeding the compensation loop count to end the machining path with invalid compensation.

9. The method for applying in-machine measurement technology to a three-axis machine tool according to claim 1, characterized in that: In step 3), circular compensation is supported. By creating three measurement points on the cross-section of the cylindrical or circular hole feature of the workpiece, the machining is judged to be qualified by comparing the deviation between the theoretical value and the measured value. 1) Support loop detection; 2) Support setting an instruction to be executed after exceeding the compensation loop count to end the machining path with invalid compensation.

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