A method for quickly measuring the inner diameter of jewel bearings

Abstract

The present invention relates to a method for quickly measuring the inner diameter of a jewel bearing, which is based on a special workpiece positioning tool and is measured on a MARH three-coordinate measuring and controlling machine; the workpiece positioning tool is a rectangular plate structure, and a plurality of tool holes are evenly distributed in the horizontal and vertical directions on the upper edge of the rectangular plate, and the steps are as follows: 1. After the workpiece positioning tool is fixed on the glass plate of the MARH three-coordinate measuring and controlling machine through plasticine, the vertical side on the right side of the tool is set as the X axis, and the lower horizontal side is provided with a Y axis, and the intersection of the two sides is the origin, and a coordinate system is established; 2. The selection of measurement parameters is performed, including the determination of light intensity, the determination of Z coordinates and the determination of cycle parameters, the determination of light intensity adopts a standard block, and the influence of bottom light and top light on the aperture size is considered respectively, and when the measured inner diameter value is consistent with the standard block verification value, the adopted top light intensity value and bottom light intensity value are determined; 3. The automatic measurement program is run to successively complete the inner hole measurement of multiple workpieces. The present invention improves the measurement efficiency and measurement accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of part size measurement, and in particular relates to a method for quickly measuring the inner diameter of a jewel bearing. Background Art

[0002] The jewel bearing is a sliding bearing made of hard materials such as gemstones. It is characterized by wear resistance, high hardness, small thermal expansion coefficient, and high pressure resistance. It is one of the important parts of the gyroscope. The precision requirement of the jewel bearing is very high. Its outer diameter matches the jewel bearing seat with a clearance of 0.001-0.003; its inner diameter matches the ball head of the ball shaft with a clearance of 0.001-0.002. Its measurement accuracy determines the matching accuracy.

[0003] Depend on Figure 1 It can be seen that the outer dimensions of the jewel bearing are relatively small, and the dimensional accuracy requirements are high. The inner diameter is Φ0.600, the tolerance is 0.002, the cylindricity requirement is 0.0005, and the coaxiality requirement with the outer circle is not greater than ф0.006. It is a tiny aperture and is not suitable for contact measurement, so it can only be measured by optical measurement methods.

[0004] The commonly used measurement method is to use a Hauser vertical projector to measure the inner hole. In addition to the accuracy system error of the instrument itself, there are also many accidental errors caused by human factors, mainly including the following aspects:

[0005] (1) Errors caused by manual focusing;

[0006] (2) Find the error caused by the maximum inner diameter through manual observation and measurement;

[0007] (3) Errors caused by estimating the reading of the millimeter scale;

[0008] (4) Errors caused by measurement direction and number of times.

[0009] In addition, there are a large number of jewel bearings, and the projector has to be used to measure them one by one. The measurement process is cumbersome and time-consuming. How to improve the measurement efficiency is also an urgent problem that needs to be solved. Summary of the invention

[0010] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a method for quickly measuring the inner diameter of a jewel bearing which can improve the measurement accuracy and efficiency.

[0011] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0012] A method for quickly measuring the inner diameter of a jewel bearing, characterized in that the method is based on a dedicated workpiece positioning fixture and the measurement is completed on a MARH three-coordinate measuring and control machine;

[0013] The workpiece positioning fixture adopts a rectangular plate structure, on which a plurality of fixture holes are evenly arranged in the horizontal and vertical directions, each fixture hole is used to install a workpiece to be measured, and each fixture hole is composed of a circular hole for positioning the workpiece and square grooves symmetrically arranged on both sides of the circular hole for the workpiece clamping tool to extend into;

[0014] The measurement method includes the following steps:

[0015] Step 1: Establish a coordinate system, specifically:

[0016] First, place the tool on the glass plate of the MARH three-dimensional coordinate measuring and control machine, stick plasticine on the four corners of the tool, and fix the tool on the glass plate; then set the right vertical side of the tool as the X-axis, and the lower horizontal side as the Y-axis, and the intersection of the two sides as the origin to establish the coordinate system;

[0017] Step 2: Select the measurement parameters, including the determination of light intensity, Z coordinate and cycle parameters;

[0018] 4) Taking the standard block with the same inner hole as the workpiece to be measured as the standard, the influence of bottom light and top light on the aperture size is considered respectively. When the bottom light intensity is 0, the top light intensity is adjusted to measure the aperture of the standard block to obtain a set of measurement data. When the top light intensity is 0, the bottom light intensity is adjusted to measure the aperture of the standard block to obtain another set of test data. Considering the two sets of data comprehensively, when the measured inner diameter value is consistent with the calibration value of the standard block, the top light intensity value and the bottom light intensity value to be adopted are determined;

[0019] 5) Manually adjust the focus height of the three-dimensional coordinate measuring machine, surround the inner diameter edge of the gem bearing with two circles of different diameters, so that the inner diameter edge is between the two circles, and focus on the edge to make the inner diameter edge image clear, and determine the measured Z coordinate position;

[0020] 6) indirectly obtain the cycle parameters for the subsequent automatic measurement program based on the row and column spacing between the tooling holes;

[0021] Step 3: Run the cycle measurement program to measure multiple workpieces, specifically:

[0022] Place multiple workpieces to be measured in multiple tooling holes on the tooling one by one, select the rectangular cycle measurement program of the MARH three-coordinate measurement and control machine, input the above-established coordinate system, light intensity, determined values ​​of the Z-axis coordinates and cycle parameters into the rectangular cycle program, and then use the workpiece close to the coordinate origin as the measurement starting position, run the selected cycle measurement program, and complete the inner hole measurement of multiple workpieces one after another.

[0023] Further: there are nine tooling holes on the workpiece positioning tooling, and they are arranged in three rows and three columns.

[0024] Furthermore: the diameter of the circular hole of the tooling hole is 0.2 mm larger than the outer diameter of the workpiece to be measured.

[0025] Further: In step 2, the light intensity is determined to be 0 for the top light and 55 for the bottom light.

[0026] The present invention has the following advantages and positive effects:

[0027] 1. The present invention adopts a workpiece positioning tool that can position multiple workpieces at one time, can realize the measurement of multiple workpieces at one time, and can greatly improve the measurement efficiency.

[0028] 2. The tooling hole on the workpiece positioning tool of the present invention is slightly larger than the outer diameter of the workpiece to be measured. In addition, long grooves are provided on both sides for the workpiece clamping tool to extend into. On the one hand, it can ensure that the subsequent optical measurement lens can achieve smooth focusing, and on the other hand, it is convenient for the measurement workpiece to be taken and placed.

[0029] 3. The measuring method of the present invention obtains the best measuring light intensity through the standard block before measuring, and manually adjusts the focusing height of the three-coordinate measuring instrument, thereby ensuring the measurement accuracy of subsequent measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a dimension diagram of a jewel bearing involved in the present invention;

[0031] Figure 2 It is a structural dimension diagram of a single tool hole on the special tool of the present invention;

[0032] Figure 3 It is the structural dimension diagram of the whole special tooling of the present invention;

[0033] Figure 4 It is a schematic diagram of the present invention for installing the tool on a glass plate;

[0034] Figure 5 is a schematic diagram of determining light intensity according to the present invention;

[0035] Figure 6 It is a schematic diagram of determining cycle parameters according to the present invention. DETAILED DESCRIPTION

[0036] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0037] A quick way to measure the inner diameter of a jewel bearing, see Figure 2-6,This method is based on a dedicated workpiece positioning fixture, and the measurement is completed on a MARH three-coordinate measuring and control machine.

[0038] 1. The design of workpiece positioning tooling is as follows:

[0039] The workpiece positioning fixture adopts a rectangular plate structure, which is used to clamp multiple jewel bearings at one time, so that the three-coordinate measuring machine can measure the inner diameters of multiple jewel bearings at one time through the measurement program. First, consider the size of the aperture for placing the jewel bearing. The outer diameter of the jewel bearing is Φ2, so the designed fixture aperture must be larger than Φ2; it is also necessary to ensure that the size of the image presented under the optical measurement lens is appropriate so that it can be automatically focused within the appropriate range when focusing. Otherwise, the gap between the outer diameter of the jewel bearing and the fixture aperture is too large, and the inner diameter of the jewel bearing cannot be completely presented in the range between the two circles, resulting in focusing failure. After repeated verification, the fixture aperture size is designed to be Φ2.2, which can make the edge of the inner diameter of the jewel bearing completely present in the focusing range. Rectangular grooves are designed at both ends of the aperture to facilitate the placement and removal of jewel bearings with tweezers. The schematic diagram of a single fixture hole structure is shown in the figure. Figure 2 The inner diameter of the jewel bearing needs to be measured one by one and the measurement data needs to be recorded. If too many jewel bearings are clamped at one time, it is easy to cause confusion in the measurement data. If abnormal data appears, it will be difficult to find it. After comprehensive consideration, the tooling is designed with nine holes. The entire tooling structure is shown in Figure 3 .

[0040] 2. The specific measurement method is as follows:

[0041] 2.1. Establish a coordinate system, specifically:

[0042] Place the tool on the glass plate of the MARH three-dimensional coordinate measuring machine, glue the four corners of the tool with plasticine, and fix the tool on the glass plate. The advantages of using plasticine to fix the tool are simple and convenient. There is no external force that will not deform the tool and will not scratch the surface of the workbench. See Figure 4 .

[0043] Set the right vertical side A of the tooling as the X-axis, the lower horizontal side B as the Y-axis, and the intersection of the line connecting side A and side B as the origin to establish a coordinate system.

[0044] 2.2 Select the measurement parameters, including the determination of light intensity, Z coordinate and cycle parameters

[0045] (1) Determination of light intensity

[0046] The light source of the MARH three-dimensional coordinate measuring instrument is divided into top light and bottom light. During the measurement process, as the light intensity changes, the aperture measurement result will also change. First, determine the light intensity required to measure the inner diameter of the gem bearing, using a standard block with an inner aperture of Φ0.603 (calibrated by AVIC 304 Institute) as the standard, and consider the effects of bottom light and top light on the aperture size. Table 1 shows the statistical table of the effects of top light intensity on the aperture when the bottom light intensity is 0, and Table 2 shows the statistical table of the effects of bottom light intensity on the aperture when the top light intensity is 0.

[0047] Table 1 Statistical table of the influence of top light intensity on aperture

[0048]

[0049] Table 2 Statistical table of the influence of bottom light intensity on aperture

[0050]

[0051] It can be seen from Table 1 and Table 2 that when the bottom light intensity is 0, the measured value of the inner aperture of the standard block does not change with the change of the top light intensity. When the top light intensity is 0 and the bottom light intensity is less than 50, the measured value of the inner diameter of the standard block does not change with the change of light intensity; when the bottom light intensity is greater than 50, the measured value of the inner aperture increases with the increase of light intensity: when the top light intensity is 0 and the bottom light intensity is set to 55, the measured inner diameter value is consistent with the calibration value of the standard block.

[0052] The results of the experiment showed that when measuring the inner diameter of a jewel bearing of Φ0.6mm, a light source with a top light intensity of 0 and a bottom light intensity of 55 should be selected.

[0053] (2) Determination of Z-axis coordinates

[0054] Manually adjust the focus height of the three-dimensional coordinate measuring machine, surround the inner diameter edge of the gem bearing with two circles of different diameters, make the inner diameter edge between the two circles, and focus on the edge to make the inner diameter edge image clearest (such as Figure 5 When reaching Figure 5 When the normal curve distribution is shown, the edge of the gem bearing aperture is clearest, and the three coordinates are captured most accurately by the optical system. In order to ensure the accuracy of the measurement, each measurement must be focused.

[0055] (3) Determine and enter cycle parameters

[0056] Depend on Figure 4 It is known that each row and column can carry 3 jewel bearings, and by setting the distance, the cycle parameters are set as follows Figure 6 shown.

[0057] 2.3. Run the cycle measurement program to measure multiple workpieces, specifically:

[0058] Place multiple workpieces to be measured in multiple tooling holes on the tooling one by one, select the rectangular cycle measurement program of the MARH three-coordinate measurement and control machine, input the above-established coordinate system, light intensity, determined values ​​of the Z-axis coordinates and cycle parameters into the rectangular cycle program, and then use the workpiece close to the coordinate origin as the measurement starting position, run the selected cycle measurement program, and complete the inner hole measurement of multiple workpieces one after another.

[0059] In summary, the present invention proposes a method for quickly measuring the inner diameter of a jewel bearing, which can quickly measure the inner diameter and shape and position requirements of a jewel bearing with one-time fixing and clamping, which not only improves the measurement accuracy, but also greatly improves the measurement efficiency.

[0060] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate 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 and drawings.

Claims

1. A method for quickly measuring the inner diameter of a jewel bearing, characterized in that: This method is based on a dedicated workpiece positioning fixture and the measurement is completed on a MARH three-dimensional coordinate measuring machine; The workpiece positioning fixture adopts a rectangular plate structure, on which a plurality of fixture holes are evenly arranged in the horizontal and vertical directions, each fixture hole is used to install a workpiece to be measured, and each fixture hole is composed of a circular hole for positioning the workpiece and square grooves symmetrically arranged on both sides of the circular hole for the workpiece clamping tool to extend into; The measurement method includes the following steps: Step 1: Establish a coordinate system, specifically: First, place the tool on the glass plate of the MARH three-dimensional coordinate measuring machine, stick plasticine on the four corners of the tool, and fix the tool on the glass plate; then set the right vertical side of the tool as the X axis, the lower horizontal side as the Y axis, and the intersection of the two sides as the origin to establish the coordinate system; Step 2: Select the measurement parameters, including the determination of light intensity, Z coordinate and cycle parameters; 1) Take the standard block with the same inner hole as the workpiece to be tested as the standard, consider the influence of bottom light and top light on the aperture size respectively, when the bottom light intensity is 0, adjust the top light intensity, measure the aperture of the standard block, and obtain a set of measurement data; when the top light intensity is 0, adjust the bottom light intensity, measure the aperture of the standard block, and obtain another set of test data; comprehensively consider the two sets of test data, and determine the top light intensity value and bottom light intensity value to be used when the measured inner diameter value is consistent with the standard block verification value; 2) Manually adjust the focus height of the coordinate measuring machine, surround the inner diameter edge of the gem bearing with two circles of different diameters, so that the inner diameter edge is between the two circles, focus on the edge to make the inner diameter edge image clear, and determine the measured Z coordinate position; 3) Obtaining cycle parameters for subsequent automatic measurement programs based on the row and column spacing between tooling holes; Step 3: Run the cycle measurement program to measure multiple workpieces, specifically: Place multiple workpieces to be measured in multiple tooling holes on the tooling one by one, select the rectangular cycle measurement program of the MARH three-coordinate measuring and control machine, input the above-established coordinate system, light intensity, determined values ​​of the Z-axis coordinates and cycle parameters into the rectangular cycle program, then take the workpiece close to the coordinate origin as the measurement starting position, run the selected cycle measurement program, and complete the inner hole measurement of multiple workpieces one after another.

2. The method for quickly measuring the inner diameter of a jewel bearing according to claim 1, characterized in that: There are nine tooling holes on the workpiece positioning tooling, which are arranged in three rows and three columns.

3. The method for quickly measuring the inner diameter of a jewel bearing according to claim 1, characterized in that: The diameter of the circular hole of the tooling hole is 0.2 mm larger than the outer diameter of the workpiece to be measured.

4. The method for quickly measuring the inner diameter of a jewel bearing according to claim 1, characterized in that: In step 2, the light intensity is determined to be 0 for the top light and 55 for the bottom light.

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