Method for improving clamping precision of flexible bent frame

Abstract

The invention discloses a method for improving the clamping precision of a flexible bent frame, and relates to the technical field of numerical control machining, and the method comprises the steps: obtaining the space coordinates P1 (x1, y1, z1) and P2 (x2, y2, z2) of positioning reference points of a positioning hole and a mark hole in a part digital model; the skin part is clamped on a flexible bent frame, positioning datum point space coordinates S1 (x3, y3 and z3) and S2 (x4, y4 and z4) of a positioning hole and a mark hole in actual clamping of the skin part are obtained, and the coordinate deviation absolute value of the positioning hole and the mark hole is obtained; and judging whether the absolute value of the coordinate deviation of the positioning hole and the mark hole is within the tolerance range or not, and if not, readjusting the mounting positions of the skin part and the flexible bent frame until the absolute value of the coordinate deviation is within the tolerance range. According to the method, the positioning hole and the mark hole of the skin part are used for joint positioning, the difference between a theoretical positioning point designed in a digital model and an actually-measured positioning point can be quantitatively measured by comparing the theoretical positioning point and the actually-measured positioning point, accurate positioning is carried out, and the problem that the flexible bent frame cannot clamp the large-curvature complex skin part is effectively solved.

Description

Technical Field

[0001] The present application relates to the technical field of numerical control machining, and in particular to a method for improving the clamping accuracy of flexible racks. Background Art

[0002] At present, in the process of processing skin parts using the flexible rack of CNC machine tools, the known positioning method is to drill positioning holes and marking holes at both ends of the skin parts. The positioning holes are used for skin clamping and positioning, and the marking holes determine the skin clamping direction. According to the characteristics of the formed skin parts, the CNC adjustment positioner is used to ensure that the normal line of the positioning pin on the positioner coincides with the normal line of the positioning hole of the skin part. The center of the spherical positioning pin is used as the processing reference. The skin part is fixed by the adjusted positioner, and the skin part is tightened by the vacuum suction cup on the flexible rack. However, for complex skin parts with large curvature, the existing clamping method will be used for positioning, and the positioning accuracy will be low, the parts are easy to offset, resulting in processing deviations, which cannot meet the process requirements of skin part production and manufacturing, so that the existing large curvature skin parts cannot be produced and processed using CNC machine tools. Summary of the invention

[0003] The main purpose of the present application is to provide a method for improving the clamping accuracy of a flexible rack, aiming to solve the technical problem that the existing flexible rack clamping positioning method cannot accurately position skin parts with large curvature.

[0004] The technical solutions adopted in this application are as follows:

[0005] A method for improving the clamping accuracy of a flexible rack, comprising:

[0006] Get the spatial coordinates of the positioning reference points P1(x1,y1,z1) and P2(x2,y2,z2) of the positioning holes and marking holes in the part digital model;

[0007] Clamp the skin parts on the flexible rack, and obtain the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and the marking holes in the actual clamping of the skin parts;

[0008] Based on the spatial coordinates P1 (x1, y1, z1) and P2 (x2, y2, z2) of the positioning reference points of the positioning holes and the marking holes in the part digital model and the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and the marking holes in the actual clamping of the skin parts, the absolute values ​​of the coordinate deviations of the positioning holes and the marking holes are obtained;

[0009] Determine whether the absolute value of the coordinate deviation of the positioning hole and the marking hole is within the tolerance range. If not, readjust the installation position of the skin part and the flexible rack until the absolute value of the coordinate deviation is within the tolerance range.

[0010] Optionally, the step of obtaining the spatial coordinates P1 (x1, y1, z1) and P2 (x2, y2, z2) of the positioning reference points of the positioning holes and the marking holes in the part digital model includes:

[0011] Determine the positions of positioning holes and marking holes in the part digital model;

[0012] Draw a straight line along the normal direction of the part plane where the locating hole and the marking hole are located, and the position with a distance equal to the radius of the spherical locating pin is used as the positioning reference point P1 and P2. The spatial coordinates of point P1 and point P2 relative to the machine tool coordinate origin are the spatial coordinates of the positioning reference points of the locating hole and the marking hole in the part digital model, P1 (x1, y1, z1) and P2 (x2, y2, z2).

[0013] Optionally, obtain the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and the marking holes in the actual clamping of the skin parts, including:

[0014] After the skin parts are clamped on the flexible rack, the suction cups on the flexible rack are turned on to vacuum absorb the skin parts;

[0015] After the skin parts are completely adsorbed and fixed, take out the spherical positioning pins in the positioning holes and marking holes, observe whether the parts are deformed and offset, and then install the spherical positioning pins into the positioning holes and marking holes again;

[0016] The gantry laser head on the CNC machine tool is used to detect the spatial coordinates of the center of the spherical locating pin on the positioning hole and the marking hole relative to the machine tool, which are the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning hole and the marking hole in the actual clamping of the skin parts.

[0017] Optionally, when the skin parts are clamped on the flexible rack, it is necessary to ensure that the normal line of the spherical locating pin coincides with the normal line of the corresponding locating hole and the marking hole.

[0018] Optionally, after the skin part is completely adsorbed and fixed, the vacuum degree measured on each column used to support the skin part needs to be greater than 90%.

[0019] Optionally, the obtaining of the absolute values ​​of the coordinate deviations of the locating holes and the marking holes based on the spatial coordinates of the locating reference points P1 (x1, y1, z1), P2 (x2, y2, z2) of the locating holes and the marking holes in the part digital model and the spatial coordinates of the locating reference points S1 (x3, y3, z3), S2 (x4, y4, z4) of the locating holes and the marking holes in the actual clamping of the skin part comprises:

[0020] Calculate the difference between the corresponding coordinates of P1(x1,y1,z1) and P2(x2,y2,z2) to obtain the reference vector P(x1-x2,y1-y2,z1-z2);

[0021] Calculate the difference between the corresponding coordinates of S1 (x3, y3, z3) and S2 (x4, y4, z4) to obtain the measurement vector S = (x3-x4, y3-y4, z3-z4);

[0022] By subtracting the corresponding coordinate values ​​of the measurement vector and the reference vector, the absolute values ​​of the coordinate deviations of the positioning hole and the marking hole can be obtained.

[0023] Optionally, the tolerance range is less than or equal to 0.5.

[0024] Compared with the prior art, the beneficial effects of this application are:

[0025] The present application proposes a method for improving the clamping accuracy of flexible racks, which utilizes the positioning holes and marking holes of skin parts for joint positioning. By comparing the theoretical positioning points designed in the digital model with the actually measured positioning points, the difference between the two can be quantitatively measured for precise positioning, which effectively solves the problem that the flexible racks cannot clamp complex skin parts with large curvatures. In addition, CNC machine tools can be used to perform measurements on the flexible racks to provide the error between the actual clamping and the theoretical value, making it convenient for operators to adjust parts in a timely manner for precise positioning. This method can further improve the accuracy of parts processed by CNC machine tools. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0027] The embodiment of the present application provides a method for improving the clamping accuracy of a flexible rack, comprising:

[0028] S1: Get the spatial coordinates of the positioning reference points P1 (x1, y1, z1) and P2 (x2, y2, z2) of the positioning holes and marking holes in the part digital model;

[0029] S2: Clamp the skin parts on the flexible rack, and obtain the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and marking holes in the actual clamping of the skin parts;

[0030] S3: Based on the spatial coordinates P1 (x1, y1, z1) and P2 (x2, y2, z2) of the positioning reference points of the positioning holes and the marking holes in the part digital model and the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and the marking holes in the actual clamping of the skin parts, the absolute values ​​of the coordinate deviations of the positioning holes and the marking holes are obtained;

[0031] S4: Determine whether the absolute value of the coordinate deviation of the positioning hole and the marking hole is within the tolerance range. If not, readjust the installation position of the skin part and the flexible rack until the absolute value of the coordinate deviation is within the tolerance range.

[0032] It can be found that this method uses the positioning holes and marking holes of the skin parts for joint positioning. By comparing the theoretical positioning points designed in the digital model with the actually measured positioning points, the gap between the two can be quantitatively measured for precise positioning, which effectively solves the problem that the flexible rack cannot clamp complex skin parts with large curvature. In addition, CNC machine tools can be used for measurement on the flexible rack to give the error between the actual clamping and the theoretical value, which is convenient for operators to adjust parts in time and perform precise positioning. This method can further improve the accuracy of parts processed by CNC machine tools.

[0033] Specifically:

[0034] The present application provides a method for improving the clamping accuracy of a flexible rack, and the detailed steps are as follows:

[0035] First, determine the positioning holes and marking holes of the parts according to the actual processing technology. The positioning holes are used for skin clamping and positioning, and the marking holes determine the skin clamping direction.

[0036] Then, make a positioning hole and a marking hole in the part digital model respectively, and make a straight line along the normal direction of the part plane where the positioning hole and the marking hole are located. The position with a distance equal to the radius of the spherical positioning pin is used as the positioning reference point (that is, the center position of the spherical positioning pin). The positioning reference point where the positioning hole is located is recorded as P1, and the positioning reference point where the marking hole is located is recorded as P2. The spatial coordinates of P1 and P2 relative to the machine tool coordinate origin are obtained as P1 (x1, y1, z1), P2 (x2, y2, z2). The x, y, and z coordinate values ​​of the two spatial coordinates of P1 and P2 are subtracted correspondingly (x1-x2, y1-y2, z1-z2), and the differences in the three directions of x, y, and z are obtained as reference vectors. That is, P(x p ,y p ,z p )=(P 1 –P 2 )=(x 1 -x 2 ,y 1 -y 2 ,z1 -z 2 );

[0037] Then, install the skin parts on the flexible rack, adjust the positioner to ensure that the normal of the spherical positioning pin coincides with the normal of the corresponding positioning hole and the marking hole, ensure the accuracy of the processing reference, and install two spherical positioning pins on the positioner. After the skin parts are installed on the flexible rack, the suction cup on the flexible rack turns on the vacuum, and the vacuum degree measured on each column supporting the parts needs to be greater than 90%. The purpose is to restore the surface changes that may occur in the previous process of the skin parts to the theoretical surface of the parts after vacuum adsorption. After the parts are adsorbed, take out the two spherical positioning pins from the positioner respectively. After taking them out, observe that the parts should not have any deformation and offset, and then install the spherical positioning pins on the positioner. During the process of removing and installing the spherical positioning pins, there should be no increase in friction, otherwise it can be regarded as that the part has undergone micro-deformation near the positioning hole. If micro-deformation occurs, it needs to be re-clamped;

[0038] Finally, the gantry laser head on the CNC machine tool is used to detect the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the center of the spherical locating pin on the positioning hole and the marking hole relative to the origin of the machine tool coordinate system. The x, y, and z coordinate values ​​of the two measured spatial coordinates S1 and S2 are subtracted correspondingly to obtain the differences in the x, y, and z directions, respectively, as the measurement vector That is, S(x s ,y s ,z s )=(S 1 –S 2 )=(x 3 -x 4 ,y 3 -y 4 ,z 3 -z 4 ), subtract the coordinate values ​​corresponding to the measured vector and the reference vector to obtain the deviation vector, that is, D = S–P = (x s -x p ,y s -y p ,z s -z p ), the absolute values ​​of the three directions of the deviation vector are the differences between the clamping process and the theoretical design, that is, |D|=|S–P|=(|x s -x p |,|y s -y p |,|z s -z p|); if the three differences are all less than or equal to 0.5mm, it can be approximately considered that the relative position of the part relative to the flexible rack is consistent with the design in the digital model. If any of the directions is greater than 0.5mm, it needs to be reinstalled, and finally the three coordinates of the measured deviation vector are all less than or equal to 0.5mm to meet the requirements. After the positioning is correct, the subsequent CNC machining process of the part can be carried out.

[0039] In summary, this method uses the positioning holes and direction holes of the skin parts for joint positioning. By comparing the theoretical positioning points designed in the digital model with the actual measured positioning points, the gap between the two can be quantitatively measured for precise positioning. In addition, the vacuum support columns of the flexible rack are used to absorb the parts to reduce the micro-deformation of the parts. The skin parts can be effectively and accurately positioned in the flexible rack of the CNC machine tool, further improving the accuracy of the parts processed by the CNC machine tool.

[0040] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for improving the clamping accuracy of a flexible rack, characterized in that: include: Get the spatial coordinates of the positioning reference points P1(x1,y1,z1) and P2(x2,y2,z2) of the positioning holes and marking holes in the part digital model; Clamp the skin parts on the flexible rack, and obtain the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and the marking holes in the actual clamping of the skin parts; Based on the spatial coordinates P1 (x1, y1, z1) and P2 (x2, y2, z2) of the positioning reference points of the positioning holes and the marking holes in the part digital model and the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning holes and the marking holes in the actual clamping of the skin parts, the absolute values ​​of the coordinate deviations of the positioning holes and the marking holes are obtained; Determine whether the absolute value of the coordinate deviation of the positioning hole and the marking hole is within the tolerance range. If not, readjust the installation position of the skin part and the flexible rack until the absolute value of the coordinate deviation is within the tolerance range.

2. The method for improving the clamping accuracy of the flexible rack according to claim 1 is characterized in that: The method of obtaining the spatial coordinates P1 (x1, y1, z1) and P2 (x2, y2, z2) of the positioning reference points of the positioning holes and the marking holes in the part digital model includes: Determine the positions of positioning holes and marking holes in the part digital model; Draw a straight line along the normal direction of the part plane where the locating hole and the marking hole are located, and the position with a distance equal to the radius of the spherical locating pin is used as the positioning reference point P1 and P2. The spatial coordinates of point P1 and point P2 relative to the machine tool coordinate origin are the spatial coordinates of the positioning reference points of the locating hole and the marking hole in the part digital model, P1 (x1, y1, z1) and P2 (x2, y2, z2).

3. The method for improving the clamping accuracy of flexible racks according to claim 1 is characterized in that: Obtain the spatial coordinates S1(x3,y3,z3) and S2(x4,y4,z4) of the positioning reference points of the positioning holes and marking holes in the actual clamping of the skin parts, including: After the skin parts are clamped on the flexible rack, the suction cups on the flexible rack are turned on to vacuum absorb the skin parts; After the skin parts are completely adsorbed and fixed, take out the spherical positioning pins in the positioning holes and marking holes, observe whether the parts are deformed and offset, and then install the spherical positioning pins into the positioning holes and marking holes again; The gantry laser head on the CNC machine tool is used to detect the spatial coordinates of the center of the spherical locating pin on the positioning hole and the marking hole relative to the machine tool, which are the spatial coordinates S1 (x3, y3, z3) and S2 (x4, y4, z4) of the positioning reference points of the positioning hole and the marking hole in the actual clamping of the skin parts.

4. The method for improving the clamping accuracy of flexible racks according to claim 3 is characterized in that: When the skin parts are clamped on the flexible rack, it is necessary to ensure that the normal line of the spherical locating pin coincides with the normal line of the corresponding locating hole and marking hole.

5. The method for improving the clamping accuracy of flexible racks according to claim 3 is characterized in that: After the skin part is completely adsorbed and fixed, the vacuum degree measured by each column used to support the skin part needs to be greater than 90%.

6. The method for improving the clamping accuracy of flexible racks according to claim 1 is characterized in that: The method of obtaining the absolute value of the coordinate deviation of the positioning hole and the marking hole based on the positioning reference point spatial coordinates P1 (x1, y1, z1), P2 (x2, y2, z2) of the positioning hole and the marking hole in the part digital model and the positioning reference point spatial coordinates S1 (x3, y3, z3), S2 (x4, y4, z4) of the positioning hole and the marking hole in the actual clamping of the skin part includes: Calculate the difference between the corresponding coordinates of P1(x1,y1,z1) and P2(x2,y2,z2) to obtain the reference vector P(x1-x2,y1-y2,z1-z2); Calculate the difference between the corresponding coordinates of S1 (x3, y3, z3) and S2 (x4, y4, z4) to obtain the measurement vector S = (x3-x4, y3-y4, z3-z4); By subtracting the corresponding coordinate values ​​of the measurement vector and the reference vector, the absolute values ​​of the coordinate deviations of the positioning hole and the marking hole can be obtained.

7. The method for improving the clamping accuracy of flexible racks according to claim 1 is characterized in that: The tolerance range is less than or equal to 0.5.