Processing center coordinate origin offset error and boring position degree test method

Abstract

The present application relates to a kind of machining center coordinate origin offset error and boring position degree test method, comprising the following steps:1) processing test piece;2) positioning test piece and determining machining coordinate system;3) test piece detection reference processing;4) machine tool empty load and load operation;5) test piece is detected feature processing;6) test piece error detection.This method carries out reasonable planning design to test piece processing process, and processing process is divided into three parts according to time sequence, test piece detection reference processing, machine tool empty load and load operation and test piece is detected feature processing;Test piece machining precision can keep the precision of machine tool, especially to coordinate origin offset error and boring position degree, so that machine tool precision test work is more comprehensive.

Description

TECHNICAL FIELD

[0001] The application relates to a machining center coordinate origin offset error and boring position degree testing method and belongs to the technical field of machine tool precision calibration methods. BACKGROUND

[0002] Currently, machine tool manufacturers determine the delivery inspection standards of machining center type machine tools by referring to the GB / T 18400 machining center inspection conditions standard. The machining precision of the profile finishing test piece of the machine tool meets the standard requirements, that is, the delivery conditions are met. However, the profile finishing test piece has a short machining cycle, and the machining detection of the test piece can only reflect the short-time precision state of the machine tool. During long-time operation of the machine tool, especially during the cold machine to hot machine process, the influence of thermal error on the machining precision accounts for a large proportion. Therefore, the profile finishing test piece is slightly insufficient as a standard test piece for evaluating the machine tool, and the precision test of the machine tool is not comprehensive enough. SUMMARY

[0003] The technical problem to be solved by the application is to provide a machining center coordinate origin offset error and boring position degree testing method. The method reasonably plans and designs the test piece machining process, and the machining process is divided into three parts in time sequence, that is, test piece detection reference machining, machine tool empty load and load operation and test piece detected feature machining. The test piece machining precision can fully display the precision maintainability of the machine tool, especially the coordinate origin offset error and the boring position degree, so that the machine tool precision test work is more comprehensive.

[0004] To solve the above problems, the specific technical scheme of the application is as follows: a machining center coordinate origin offset error and boring position degree testing method, comprising the following steps:

[0005] 1) Pre-machining test piece: the test piece adopts a cylindrical structure, and four countersunk screw holes are arranged on the circumference; a boring bottom hole is pre-drilled on the test piece; and a positioning reference plane is milled on the circumferential surface;

[0006] 2) Positioning the test piece and determining the machining coordinate system: the test piece is pre-fixed on the machine tool workbench through screws and T-shaped blocks, a dial indicator is used to dial and align the test piece, the parallelism between the reference plane and the machine tool X-axis is ensured to be less than 0.01 mm, then the fixing screws are tightened, and the positioning of the test piece is completed; an edge finder contacts the outer circumference of the test piece from the X+, X-, Y+ and Y- directions to determine the center position of the test piece, and the position is taken as the origin of the machining coordinate system;

[0007] 3) Test piece detection reference machining: after the length of each tool is set, a standard test machining program is executed to machine the detection reference, that is, to mill the outer circumference, the top surface and the positioning reference plane of the test piece with a diameter D;

[0008] 4) Machine tool empty load and load operation: the machine tool is operated in empty load or load, the empty load operation includes milling plane, milling circle, chamfering, drilling, boring, tool changing and other empty operation actions, at this time the machine tool does not carry out material cutting, the load operation is that the machine tool cuts the 45# steel test piece in a dynamic milling manner;

[0009] 5) The test piece is processed by the detected feature: the test piece is processed by setting the program, that is, the small holes with a small diameter are drilled in sequence, six of which are distributed in a small diameter circle, six of which are distributed in another large diameter circle, and one small hole is located at the center axis of the test piece;

[0010] 6) Test piece error detection: taking the top surface, the circumference surface with diameter D and the reference plane of the test piece as the reference, a measurement coordinate system is established, and the center coordinates and roundness of each hole are measured by a three-coordinate measuring instrument; the coordinate origin offset of the center hole and the reference A is the coordinate origin offset, and the position degree of the remaining small holes relative to the reference A is the boring position degree in the test process. The axis of the center hole is the reference B, and the position degree of each hole relative to the reference B is the boring position degree in the thermal stability state of the machine tool.

[0011] In the processing test piece step, a chip removal groove is processed in advance on the bottom surface of the test piece, the chip removal groove corresponds to the small hole processed in the fourth step, and the bottom surface of the test piece is precisely milled to have a flatness of less than 0.02 mm.

[0012] According to the center coordinate origin offset error and the deviation value of the boring position degree obtained in the sixth step, the measurement result is corrected to eliminate the detection error.

[0013] The machining center coordinate origin offset error and boring position degree test method of the application adopts the above steps, and has the following beneficial effects:

[0014] 1. The test piece can be flexibly arranged according to the structure of the machine tool, and the machining precision of different working positions of the machine tool can be tested according to specific needs; and the test piece can be repeatedly used for multiple times, and the test cost is low;

[0015] 2. The processing process of the test piece is divided into three parts in time sequence, the test piece detection reference processing, the machine tool empty load and load operation, and the test piece detected feature processing; the test piece machining precision can fully reflect the coordinate origin offset error and the boring position degree of the machine tool precision maintainability;

[0016] 3. The correction process of the test piece detection data can maximize the elimination of detection error and truly and comprehensively reflect the machine tool precision. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a machining schematic front view of the application.

[0018] Figure 2 This is a top view illustrating the processing of this application.

[0019] Figure 3 This is a top view of the test piece.

[0020] Figure 4 This is a alphabetical diagram for machining small holes.

[0021] Figure 5 for Figure 3 CC section view.

[0022] Figure 6 A schematic diagram for measuring coordinate deviation of the test piece. Detailed Implementation

[0023] like Figures 1 to 5 As shown, a method for testing the coordinate origin offset error and boring hole position accuracy of a machining center includes the following steps:

[0024] 1) Machining the test piece: Test piece 2 adopts a cylindrical structure with four countersunk screw holes 2-1 around its circumference; a positioning reference plane 2-2 is milled on the circumferential surface of test piece 2; simultaneously, a chip removal groove 2-3 is pre-machined on the bottom surface of test piece 2, the chip removal groove 2-3 corresponding to the position of the small hole machined in step 4, and the bottom surface of test piece 2 is precision milled to a flatness of less than 0.02mm. Figure 5 As shown.

[0025] 2) Positioning the test piece and determining the machining coordinate system: Pre-fix the test piece 2 onto the machine tool worktable using screws and T-blocks. Use a dial indicator to align the test piece 2, ensuring that the parallelism between the reference plane 2-2 and the X-axis of the machine tool is less than 0.01mm. Then tighten the fixing screws to complete the positioning of the test piece 2. Use an edge finder to contact the outer circumference of the test piece 2 from the X+, X-, Y+, and Y- directions respectively to determine the center position of the test piece 2. Use this position as the origin of the machining coordinate system.

[0026] 3) Machining of test piece inspection datum: After setting the length of each tool, execute the standard test machining program to machine the inspection datum, that is, mill the outer circumference, top surface and positioning datum plane 2-2 of test piece 2 with diameter D;

[0027] 4) Machine tool no-load and load operation: The machine tool performs no-load operation 7 or load operation 6. No-load operation includes no-load operation actions such as milling plane, milling circle, chamfering, drilling, boring, and tool changing. During this time, the machine tool does not cut materials. Load operation is when the machine tool cuts 45# steel sample 5 in a dynamic milling manner.

[0028] 5) Processing of the test piece's inspected features: Process test piece 2 according to the set program, i.e., according to... Figure 3 and Figure 4The letters a to m shown are used to bore small holes of diameter d in sequence. Six of the holes are distributed around the same small diameter d1 circle, and the other six holes are distributed around another large diameter d2 circle. There is also a small hole located at the central axis of test piece 2.

[0029] 6) Feature Inspection of Test Part: Using the top surface of test part 2, the circumferential surface of diameter D, and reference plane 2-2 as references, establish a measurement coordinate system. Use a coordinate measuring machine to measure the center coordinates and roundness of each hole. The measurement data should be based on the measurement coordinate system. Since there may be deviations between the measurement coordinate system and the machining coordinate system, such as… Figure 6 The measurement results need to be corrected to eliminate detection errors;

[0030] 7) Measurement result correction processing: Take the average of the ratio of the difference in Y coordinates between holes a and d to d1, and the ratio of the difference in Y coordinates between holes g and j to d2, and then calculate the arcsine function to obtain the relative deflection angle α between the workpiece measurement coordinate system X'OY' and the machining coordinate system XOY. Use the relative deflection angle α as the coordinate transformation angle, and calculate the coordinate value of the center of hole am in the machining coordinate system XOY through the coordinate transformation formula.

[0031] by This represents the X-coordinate of the center of hole a in the measurement coordinate system. This represents the Y-coordinate of the center of hole a in the measurement coordinate system; This represents the X-coordinate of the center of hole a in the machining coordinate system. This represents the Y-coordinate of the center of hole a in the machining coordinate system;

[0032] Relative deflection angle of coordinate system:

[0033]

[0034] Coordinate transformation process:

[0035]

[0036] After transformation, the coordinates of the center of each hole can be used to determine the offset error of the coordinate origin and the boring position. The difference between the coordinates of hole m and the reference A is the offset of the coordinate origin, and the position of holes af and gl relative to the reference A is the boring position during the test process; the axis of the center hole is the reference B, and the position of holes af and gl relative to the reference B is the boring position under the thermal stability state of the machine tool.

Claims

1. A method for testing the coordinate origin offset error and boring hole position accuracy of a machining center, characterized in that... Includes the following steps: 1) Machining the test piece: The test piece (2) adopts a cylindrical structure and has four countersunk screw holes (2-1) around its circumference; pre-drill the bottom hole of the boring hole on the test piece (2); and mill the positioning reference plane (2-2) on the circumference surface. 2) Positioning the test piece and determining the machining coordinate system: Pre-fix the test piece (2) on the machine tool worktable (3) with screws and T-blocks, use a dial indicator to align the test piece (2) and ensure that the parallelism between the reference plane (2-2) and the X-axis of the machine tool is less than 0.01mm. Then tighten the fixing screws to complete the positioning of the test piece (2); use an edge finder to contact the outer circumference of the test piece (2) from the X+, X-, Y+, and Y- directions respectively to determine the center position of the test piece (2), and use this position as the origin of the machining coordinate system. 3) Machining of test piece inspection datum: After setting the length of each tool (1), execute the standard test machining program to machine the inspection datum, that is, mill the outer circumference, top surface and positioning datum plane (2-2) of the test piece (2) diameter D. 4) Machine tool no-load and load operation: The machine tool performs no-load operation (7) or load operation (6). No-load operation includes no-load operation actions such as milling plane, milling circle, chamfering, drilling, boring and tool changing. At this time, the machine tool does not perform material cutting. Load operation is when the machine tool cuts 45# steel sample in dynamic milling mode (5). 5) Processing of the test piece's detected features: The test piece (2) is processed according to the set program, that is, the small holes of diameter d are bored in sequence, of which six small holes are distributed in the same small diameter circle, the other six small holes are distributed in another large diameter circle, and one small hole is located at the central axis of the test piece (2); 6) Test piece error detection: With the top surface of the test piece (2), the circumferential surface of the diameter D and the reference plane (2-2) as references, establish a measurement coordinate system, and use a coordinate measuring machine to measure the center coordinates and roundness of each hole; the difference between the coordinates of the center hole and the reference A is the offset of the coordinate origin, and the position of each of the other small holes relative to the reference A is the boring position of the test process. The axis of the center hole is the reference B, and the position of each hole relative to the reference B is the boring position of the machine tool in thermal stability state.

2. The method for testing the coordinate origin offset error and boring position accuracy of a machining center as described in claim 1, characterized in that: In the process of processing the test piece, a chip removal groove (2-3) is pre-processed on the bottom surface of the test piece (2). The chip removal groove (2-3) corresponds to the position of the small hole processed in step 5). The bottom surface of the test piece (2) is precision milled to a flatness of less than 0.02 mm.

3. The method for testing the coordinate origin offset error and boring position accuracy of a machining center as described in claim 1, characterized in that: Based on the deviation values ​​of the machining center coordinate origin offset error and the boring hole position obtained in step 6), the measurement results are corrected to eliminate the detection error.

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