A three-coordinate measuring machine star probe alignment device and its use method

Abstract

The present invention relates to a three-coordinate measuring machine star probe alignment device and a use method. The device body is a rectangular plate with a center hole. Positioning through holes that are compatible with three positioning posts of the star probe are evenly distributed around the center hole. Two reference surfaces are opened at both ends of the long side of the rectangular plate. The alignment device is simple to manufacture, low in cost, and convenient and efficient to use. Using the alignment device of the present invention, a simple and efficient three-coordinate measuring machine star probe alignment method can be realized, which solves the problem that the traditional naked eye observation alignment angle deviation cannot be guaranteed, effectively improves the alignment accuracy and thus ensures the accuracy of three-coordinate measurement.

Description

Technical Field

[0001] The invention belongs to the field of mechanical engineering and relates to a three-coordinate measurement technology, in particular to a three-coordinate measuring machine star probe alignment device and a use method. Background Art

[0002] With the rapid development of the manufacturing industry, the application of three-dimensional coordinate measuring machines (CMMs) is becoming increasingly widespread, especially in precision machining fields such as machinery, automobiles, aviation, and military applications. The dimensions and form and position tolerances of many complex parts require three-dimensional measurement, but traditional measurement methods cannot meet production needs. With their high precision, high efficiency, and excellent automation and digitalization capabilities, CMMs have become a vital tool for manufacturing and quality assurance.

[0003] When measuring parts using a CMM, the stylus's spherical ball contacts the surface of the part being measured. The difference between the contact point and the actual coordinates transmitted to the software is one spherical ball radius. This radius is then accurately applied to the measurement point to determine the actual coordinate position of the contact point. Once the measurement is complete, the software then fits these measurement points into measurement elements for dimensional and geometric tolerance assessment.

[0004] A star probe is the primary measuring component of a coordinate measuring machine (CMM). Conventional CMMs can only move along the X, Y, and Z directions of their machine coordinate system. To ensure that the ball, rather than the stylus, contacts the workpiece surface during measurement, the star probe must be aligned during installation. This means ensuring that the orientation of its four stylus pins aligns with the machine coordinate system. Traditional alignment methods involve attaching the star probe to a suction cup, attaching the cup using a CMM, and visually aligning the probe. However, this approach cannot guarantee angular deviation, and any contact between the stylus and the part during measurement can lead to erroneous results. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a three-coordinate measuring machine star probe alignment device and a method of use, which can achieve off-machine alignment and ensure that the four stylus needles in the horizontal direction of the three-coordinate are consistent with the direction of the machine coordinate system.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A method for aligning a star-shaped probe of a three-dimensional coordinate measuring machine, the specific steps of the method are as follows:

[0008] (1) After connecting the suction cup, connecting rod and measuring needle of the three-dimensional coordinate measuring machine probe, place the three positioning columns of the suction cup on the three positioning holes of the three-dimensional coordinate measuring machine star probe alignment device and fix them;

[0009] (2) Place the entire structure assembled in step (1) on a milling machine or a device with three displacement directions: X, Y, and Z;

[0010] (3) Move the milling machine in the X direction and make the reference surface of the alignment device parallel to the X direction. Use the lever dial indicator to align the A surface so that its parallelism with the X direction of the milling machine is ≤0.01;

[0011] (4) Move the milling machine in the Z direction to measure the stylus rods of the corresponding directions, record the deviation direction and value of the two stylus rods, loosen the top screw on the suction cup, and rotate the connecting rod for fine adjustment to make the two connecting rods parallel to the reference plane;

[0012] (5) Measure the deviation direction and value of the two probes again, repeat the operation until the parallelism between the two probes and the reference surface is ≤0.01, tighten the screw so that the connecting rod can no longer rotate, and move the Z direction of the milling machine in step (5) to measure the probe rods of the probes in the corresponding directions respectively. The probes refer to the 1# probe and 3# probe corresponding to the 1# positioning through hole and the 3# positioning through hole. After the alignment is completed, the cumulative parallelism error with the X direction of the three-dimensional coordinate measuring machine is ≤0.04.

[0013] After the 1# stylus and the 3# stylus are aligned, the other two stylus do not need to be aligned again and are automatically kept consistent with the Y direction of the three-dimensional coordinate measuring machine.

[0014] Moreover, the three-coordinate measuring machine star probe alignment device has a main body which is a rectangular plate with a center hole. Positioning holes that are compatible with the three positioning columns of the star probe are evenly distributed around the center hole, namely 1# positioning hole, 2# positioning hole, and 3# positioning hole. The center hole is compatible with the mounting part of the suction cup, and two reference surfaces are opened at both ends of the long side of the rectangular plate.

[0015] Moreover, the flatness of the reference surface is ≤0.005, and the flatness of the line connecting the centers of the 1# positioning through hole and the 2# positioning through hole and the reference surface is ≤0.01, so as to ensure that the flatness of the reference surface in the X direction and the machine coordinate system is ≤0.01.

[0016] Moreover, a processing groove is opened between the two reference surfaces.

[0017] The advantages and positive effects of the present invention are:

[0018] The present invention is scientifically and rationally designed, and has developed a device and method for aligning a star probe of a three-coordinate measuring machine. The alignment device is simple to manufacture, low in cost, and convenient and efficient to use. The alignment device of the present invention can realize a simple and efficient method for aligning a star probe of a three-coordinate measuring machine, solves the problem that the traditional naked eye observation cannot guarantee the deviation of the alignment angle, effectively improves the alignment accuracy and thus ensures the accuracy of three-coordinate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of a coordinate measuring machine probe in the prior art;

[0020] Figure 2 for Figure 1 Schematic diagram of the structural distribution of the positioning column on the top of the middle suction cup;

[0021] Figure 3 This is a structural diagram of the alignment device of the present invention;

[0022] Figure 4 for Figure 3 Usage status diagram;

[0023] Figure 5 It is a schematic diagram of the alignment method of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0025] The structure of the probe of the coordinate measuring machine in the prior art is as follows: Figure 1 As shown, it includes a suction cup 1, a connecting rod 3 and a measuring needle 4. The suction cup is installed on the upper part of the connecting rod, and a plurality of measuring needles are provided on the lower part of the connecting rod. A mounting part 1-1 is provided in the center of the suction cup, and three positioning columns 1-2 are distributed around the mounting part. The suction cup is connected to the three-dimensional coordinate measuring machine through the mounting part and the positioning columns.

[0026] The suction cup and the connecting rod, as well as the connecting rod and the measuring needle are all threadedly connected. A top screw 2 is provided at the connection between the suction cup and the connecting rod. The top screw serves as a fine-tuning function. When the connecting rod is tightened and fine-tuned to a certain angle so that the direction of the measuring needle is consistent with the direction of the machine coordinate system, the top screw is tightened to fix the connecting rod so that it no longer rotates.

[0027] like Figure 2 As shown, the distribution of the positioning posts on the suction cup is consistent with the machine coordinate system. The line connecting the centers of the 1# positioning posts and the 2# positioning posts is the X direction of the machine coordinate system, and the line perpendicular to the X direction at 90° is the Y direction of the machine coordinate system. The extension line of the Y direction is perpendicular to the line connecting the centers of the 3# positioning posts. Therefore, as long as the direction of the stylus is consistent with the three positioning posts, the direction of the stylus can be guaranteed to be consistent with the direction of the machine coordinate system.

[0028] The above is the existing method for aligning the star probe of a three-dimensional coordinate measuring machine, which is to align it manually with the naked eye. Its angle deviation cannot be guaranteed, and once the probe contacts the part during the measurement process, the measurement result will be wrong.

[0029] The present invention designs a three-coordinate measuring machine star probe alignment device, such as Figure 3 As shown, the main body is a rectangular plate 5 with a center hole 6 formed on it. Three positioning through holes 7 adapted to the positioning columns are evenly distributed around the center hole, namely, 1# positioning through hole, 2# positioning through hole, and 3# positioning through hole. The center hole is adapted to the mounting part of the suction cup.

[0030] Two reference surfaces 8 (surface A) are opened at both ends of the long side of the rectangular plate, and a processing groove 9 is opened between the two reference surfaces. The flatness of the reference surface is required to be no greater than 0.005, and the center line connecting the hole #1 positioning through hole and the hole #2 positioning through hole needs to be no more than 0.01 flat with the surface A to ensure that the flatness of the surface A in the X direction with the machine coordinate system is no more than 0.01.

[0031] A method for aligning a star-shaped probe of a three-coordinate measuring machine

[0032] (1) After connecting the suction cup, connecting rod and measuring needle of the three-dimensional coordinate measuring machine probe, place the three positioning posts of the suction cup on the three positioning holes of the alignment device of the present invention and fix them. In practice, plasticine can be used for fixing;

[0033] (2) If Figure 4 , placing the whole structure assembled in step (1) on a milling machine or a device with three displacement directions of X, Y, and Z;

[0034] (3) Figure 5 As shown, move the milling machine in the X direction and make the A surface of the alignment device parallel to the X direction. Use the lever dial indicator to align the A surface so that its parallelism with the X direction of the milling machine is not greater than 0.01.

[0035] (4) Measure the Z direction of the mobile milling machine Figure 4 Take the measuring rods of the 1# and 3# measuring probes, note the deviation direction and value of the two measuring probes, loosen the top screw on the suction cup, and gently turn the connecting rod to make fine adjustments so that the two connecting rods are as parallel as possible to the A surface;

[0036] (5) Measure the deviation direction and value of the two probes again, repeat the operation until the parallelism between the two probes and the A surface is no more than 0.01, and tighten the top screw so that the connecting rod can no longer rotate.

[0037] After the alignment of the 1# and 3# styluses is completed, the maximum cumulative parallelism error with the coordinate measuring machine in the X direction is 0.04, which basically meets the use requirements. After the 1# and 3# styluses are aligned, the other two styluses do not need to be aligned again and automatically maintain consistency with the Y direction of the coordinate measuring machine.

[0038] It should be noted that this embodiment is descriptive and not restrictive, and the milling machine or equipment used for alignment is not restrictive either. As long as it can move linearly in the X, Y, and Z directions, it does not limit the scope of protection of the present invention.

[0039] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A three-coordinate measuring machine star probe alignment device, characterized by: The main body is a rectangular plate with a center hole. Three positioning holes are evenly distributed around the center hole, which are compatible with the star probe positioning column. They are 1# positioning hole, 2# positioning hole, and 3# positioning hole. The center hole is compatible with the mounting part of the suction cup. Two reference surfaces are opened at both ends of the long side of the rectangular plate. The flatness of the reference surface is ≤0.

005. The flatness of the line connecting the center of the 1# positioning hole and the 2# positioning hole and the reference surface is ≤0.01, so as to ensure that the flatness of the reference surface in the X direction with the machine coordinate system is ≤0.

01. The above-mentioned three-coordinate measuring machine star probe alignment method has the following specific steps: (1) After connecting the suction cup, connecting rod and measuring needle of the three-dimensional coordinate measuring machine probe, place the three positioning columns of the suction cup on the three positioning holes of the three-dimensional coordinate measuring machine star probe alignment device and fix them; (2) Place the entire structure assembled in step (1) on a milling machine or a device with three displacement directions: X, Y, and Z; (3) Move the milling machine in the X direction and make the reference surface of the alignment device parallel to the X direction. Use the lever dial indicator to align the A surface so that its parallelism with the X direction of the milling machine is ≤0.01; (4) Move the milling machine in the Z direction to measure the stylus rods of the corresponding direction respectively, record the deviation direction and value of the two stylus rods, loosen the top screw on the suction cup, and rotate the connecting rod for fine adjustment to make the two stylus rods parallel to the reference plane; (5) Measure the deviation direction and value of the two probes again, repeat the operation until the parallelism between the two probes and the reference surface is ≤0.01, and tighten the top screw so that the connecting rod cannot rotate anymore.

2. The three-coordinate measuring machine star probe alignment device according to claim 1, characterized in that: A machining groove is provided between the two reference surfaces.

3. The three-coordinate measuring machine star probe alignment device according to claim 1, characterized in that: In step (5), the Z direction of the milling machine is moved to measure the stylus rods of the corresponding direction stylus respectively. The stylus refers to the 1# stylus and the 3# stylus corresponding to the 1# positioning through hole and the 2# positioning through hole. After the alignment is completed, the cumulative parallelism error with the X direction of the three-coordinate measuring machine is ≤0.

04.

4. The three-coordinate measuring machine star probe alignment device according to claim 3, characterized in that: After the 1# stylus and the 3# stylus are aligned, the other two stylus do not need to be aligned again and are automatically kept consistent with the Y direction of the three-dimensional coordinate measuring machine.

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