Method for measuring jerk value of crankshaft workpiece in three coordinates

Abstract

The invention provides a method for measuring the jerk value of a crankshaft workpiece in three coordinates, and belongs to the technical field of crankshaft detection. The method specifically comprises the following steps that (1) the crankshaft is supported in a three-coordinate measuring instrument, the two ends of the crankshaft are reference journals and are placed on a fixed support, and all the journals in the middle of the crankshaft are supported on a floating support; (2) establishing a coordinate system by taking two diameters of two ends of the crankshaft supported by the fixed support as an X-Y reference and taking X-Y as an original point; and (3) measuring the jerk value of each gear of main journals in the middle of the crankshaft relative to the X-Y reference and the jerk value of adjacent journals, and adjusting each gear of journals of the crankshaft to be in a linear relation by adjusting the crankshaft floating support. Errors caused by the dead weight of the crankshaft in three coordinates are reduced, the crankshaft journal is in a linear relation by adjusting the crankshaft floating support, the measurement precision is ensured, and errors generated by the support are eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of crankshaft detection, and in particular relates to a method for measuring the runout of a crankshaft workpiece in three coordinates. Background Art

[0002] For a long time, in the manufacturing process of diesel engines, the tolerance accuracy of the runout measurement of crankshaft workpieces needs to meet certain requirements. However, the accuracy of the runout tolerance is guaranteed by the measurement personnel adjusting the workpiece back and forth during the production and processing. There is no tooling and three-coordinate measurement for accurate measurement. If accurate measurement cannot be obtained, the workpieces put into installation and use will have quality risks, increase the cost of later maintenance, and bring many unnecessary troubles and losses. The crankshaft bracket used in the workshop is not accurate enough, and it is difficult to adjust. It cannot meet the current crankshaft measurement standard requirements and often fails to work normally. Several people must be required to operate the measurement, the inspection is labor-intensive, and the inspection efficiency is low.

[0003] The runout error refers to the change in the deviation of the measured axis relative to the reference axis. It is reflected in the eccentricity of the center of the circle on the cross section. The object of runout measurement is a rotating part. Runout detection is a test item often encountered in measurement work. Using three-coordinate measurement to detect runout is not only intuitive but also convenient. The crankshaft is supported by fixed supports and floating supports of the tooling in three-coordinate measurement. However, due to the poor linear relationship of the spindle journal caused by the crankshaft's own weight, the measurement result error is large. In order to reduce the error caused by the self-weight, it is necessary to adjust the crankshaft floating support to make the crankshaft journal linear relationship better, so as to ensure the measurement accuracy and eliminate the error caused by the support. Therefore, it is necessary to propose improvements. Summary of the invention

[0004] The technical problem solved by the present invention is: to provide a method for measuring the runout of a crankshaft workpiece in three coordinates. The purpose of the present invention is to reduce the error caused by the deadweight of the crankshaft in three coordinates. By adjusting the crankshaft floating support to make the crankshaft journals in a linear relationship, the measurement accuracy is ensured and the error caused by the support is eliminated.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for measuring the runout of crankshaft workpieces in three coordinates, which is to adjust the crankshaft floating support to make the crankshaft journals in a linear relationship, reduce the error caused by the crankshaft's own weight, ensure measurement accuracy and eliminate the error caused by the support; specifically, the following steps are included:

[0007] Step 1): The crankshaft is supported in a three-dimensional coordinate measuring machine, wherein the two ends of the crankshaft are reference journals and are placed on fixed supports, and the middle journals of the crankshaft are supported on floating supports;

[0008] Step 2): Take the two diameters of the crankshaft at both ends supported by the fixed support as the XY reference, and establish a coordinate system with XY as the origin;

[0009] Step 3): Measure the runout of each main journal of the middle part of the crankshaft relative to the XY reference and the runout of the adjacent journals, and adjust the crankshaft floating support so that the journals of each gear of the crankshaft are adjusted to a linear relationship.

[0010] In the above step 2), after the crankshaft is placed on a fixed support, the three-coordinate probe in the three-coordinate measuring machine is used to measure the two-speed reference shaft diameter in the normal direction as the XY reference, and the plane Y is measured on one end face of the crankshaft, and a coordinate system is established when the perpendicularity between the XY reference and the plane Y is within 5μm.

[0011] In the above step 3), plane Y is taken as the Y-axis direction, the worktable is taken as the Z-axis direction, the XY reference is taken as the origin coordinate (0,0), and plane Y is taken as the projection plane to measure the shaft diameter of each gear. The measured coordinates of the shaft diameter of each gear are (X1, Z1)(X2, Z2)…, wherein the deviation in the X direction is △X, and the deviation in the Z direction is △Z; according to the values ​​of the measured coordinates of the shaft diameter of each gear (X1, Z1)(X2, Z2)…, first observe the value in the X direction. If the deviation △X in the X direction is large, adjust the floating support, observe the values ​​of the shaft diameter coordinates of each gear (X1, Z1)(X2, Z2)…, and calculate the values ​​of the shaft diameter coordinate deviations (△X1, △Z1)(△X2, △Z2)… of each gear until the deviation △X in the X direction is within 0.02㎜.

[0012] Calculate the linear relationship of the journals of each gear, that is, When the linear relationship between the shaft diameters of each gear is within 0.02 mm and the support error is qualified, the crankshaft can be measured.

[0013] When adjusting the floating support, first loosen the floating support, move the floating support left and right for adjustment, and then tighten the floating support.

[0014] The advantages of the present invention compared with the prior art are:

[0015] 1. This solution uses floating adjustment technology and three-coordinate data processing to achieve multiple static measurements to simulate the dynamic measurement of the crankshaft, and the detection data is stable and reliable. The difficulties in the current medium-speed diesel engine crankshaft measurement process are analyzed, and based on the crankshaft runout detection error analysis and long-distance shaft system error analysis, a runout detection method is constructed for the crankshaft components of medium-speed diesel engines. Based on vector direction technology, coordinate system selection technology, and fitting method technology, the analysis and extraction of medium-speed diesel engine crankshaft runout elements are studied to form a method for medium-speed diesel engine crankshaft runout, realize the detection of crankshaft runout from static to dynamic, effectively prevent medium-speed diesel engine crankshaft runout detection errors, and greatly improve inspection efficiency and accuracy;

[0016] 2. This solution directly adjusts the floating support so that the crankshaft can be placed horizontally, reducing the error caused by the crankshaft's own weight, making the crankshaft journal linear relationship better, and establishing a coordinate system closer to the actual workpiece, ensuring measurement accuracy, eliminating the error caused by the support, and reducing measurement errors during three-coordinate measurement;

[0017] 3. The present invention has a simple structure, novel design, convenient operation, high runout measurement efficiency, and improves the detection accuracy and efficiency of crankshafts. It is particularly suitable for workpiece detection with high-precision runout measurement and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the front view of the crankshaft inspection assembly diagram of the present invention;

[0019] Figure 2 This is the axis diameter coordinate deviation diagram of the present invention.

[0020] Figure 3 This is the touch measurement vector direction error diagram of the present invention;

[0021] Figure 4 This is the contact compensation diagram of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] See also Figure 1-4 , describe the embodiments of the present invention in detail.

[0024] Embodiment: A method for measuring the runout of a crankshaft workpiece in three coordinates, wherein the method adjusts the crankshaft floating support to make the crankshaft journals in a linear relationship, reduces the error caused by the crankshaft deadweight, ensures the measurement accuracy and eliminates the error caused by the support; specifically, the method comprises the following steps:

[0025] Step 1): Support the crankshaft in the three-dimensional coordinate measuring machine. Figure 1 As shown, the two ends of the crankshaft are reference journals and are placed on fixed supports, and the middle journals of the crankshaft are supported on floating supports;

[0026] Step 2): Take the two diameters of the crankshaft at both ends supported by the fixed support as the XY reference, and establish a coordinate system with XY as the origin;

[0027] Step 3): Measure the runout of each main journal of the middle part of the crankshaft relative to the XY reference and the runout of the adjacent journals, and adjust the crankshaft floating support so that the journals of each gear of the crankshaft are adjusted to a linear relationship.

[0028] In the above step 2), after the crankshaft is placed on a fixed support, the three-coordinate probe in the three-coordinate measuring machine is used to measure the two-speed reference shaft diameter in the normal direction as the XY reference, and the plane Y is measured on one end face of the crankshaft, and a coordinate system is established when the perpendicularity between the XY reference and the plane Y is within 5μm.

[0029] In the above step 3), plane Y is used as the Y-axis direction, the three-coordinate measuring head is used to measure the three-coordinate worktable as the Z-axis direction, the XY reference is used as the origin coordinate (0,0), and plane Y is used as the projection plane to measure the shaft diameter of each gear. The shaft diameter measurement coordinates of each gear are (X1, Z1)(X2, Z2)..., where the X-direction deviation is △X and the Z-direction deviation is △Z. If the center position △X has a measurement error of 10μm, and △Z has a measurement error of 10μm, according to the principle of runout calculation, the measurement axis has been enlarged to 25μm. According to the runout calculation, the runout error of 25*2=50μm, if the direct evaluation result is not adjusted for support and detection methods, it cannot truly reflect the actual situation of the part. When the three-dimensional probe measures the shaft diameter, the deviation in the vector direction is generated. The coordinates of the point in the touch space are (X, Y, Z, I, J, K). I, J, K are the errors generated in the vector direction. I = R*cosA, J = sinA, R is the probe radius, and A is the contact angle between the probe and the workpiece. Figure 2 As shown in the figure, the probe radius is compensated according to the IJ value, such as Figure 3 As shown, after compensation, the accurate position of the contact point can be obtained. In order to solve the above situation, this method should be used to first eliminate the support error of the crankshaft in the three-coordinate system and then avoid it.

[0030] According to the values ​​of the shaft diameter measurement coordinates (X1, Z1)(X2, Z2)… of each gear, first observe the value in the X direction. If the X direction deviation △X is large, adjust the floating support. When adjusting the floating support, first loosen the floating support, then tighten the floating support, and let the floating support move left and right for adjustment; observe the values ​​of the shaft diameter coordinates (X1, Z1)(X2, Z2)… of each gear, and calculate the shaft diameter coordinate deviation of each gear. Figure 2 The values ​​of (△X1,△Z1)(△X2,△Z2)… are shown as follows. Adjust the left and right directions until the deviation △X in the X direction is within 0.02㎜ so that the crankshaft is not subjected to force in the left and right directions, thereby reducing the measurement error.

[0031] Calculate the linear relationship of the journals of each gear, that is, When the linear relationship between the shaft diameters of each gear is within 0.02 mm and the support error is qualified, the crankshaft can be measured.

[0032] In the above, by directly adjusting the floating support, crankshafts of different sizes can be placed horizontally, so that the crankshaft journals are in a linear relationship, reducing the measurement error during three-coordinate measurement. The floating support adopts an inlaid roller, and the roller, the bottom plate and the clamping plate are closely matched. The matching requirements are high, the stability is good, and the long-term use will not affect the accuracy. The crankshaft can be adjusted so that it is not subjected to force in the left and right directions.

[0033] The present invention eliminates the problems caused by crankshaft inspection through this method. Based on the floating support of the crankshaft workpiece in the three-coordinate measurement of the runout, the crankshaft can be flexibly adjusted in height, left and right and diameter. The runout of each main journal of the crankshaft relative to the reference and the runout of the adjacent journals are measured, and the journals of each gear of the crankshaft are adjusted into a linear relationship, ensuring the measurement accuracy and eliminating the error caused by the support, so that the crankshaft workpiece can eliminate the deformation caused by itself or the placement.

[0034] The invention has a simple structure, novel design, small size, low production cost, convenient operation, high runout measurement efficiency, and improves the detection accuracy and efficiency of the crankshaft. It is particularly suitable for workpiece detection with high-precision runout measurement and is easy to promote and use.

[0035] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0036] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for measuring the runout of a crankshaft workpiece in three coordinates, characterized in that: The method is to adjust the crankshaft floating support to make the crankshaft journals in a linear relationship, reduce the error caused by the crankshaft deadweight, ensure the measurement accuracy and eliminate the error caused by the support; specifically, the following steps are included: Step 1): Support the crankshaft in a three-dimensional coordinate measuring machine, wherein both ends of the crankshaft are reference journals and supported on fixed supports, and each gear journal in the middle of the crankshaft is supported on floating supports; Step 2): Take the two diameters of the crankshaft at both ends supported by the fixed support as the XY reference, and establish a coordinate system with XY as the origin; Step 3): Measure the runout of each main journal of the middle part of the crankshaft relative to the XY reference and the runout of the adjacent journals, and adjust the crankshaft floating support so that the journals of each gear of the crankshaft are adjusted to a linear relationship.

2. The method for measuring the runout of a crankshaft workpiece in three coordinates according to claim 1, characterized in that: In the above step 2), after the crankshaft is placed on a fixed support, the three-coordinate probe in the three-coordinate measuring machine is used to measure the two-speed reference shaft diameter in the normal direction as the XY reference, and the plane Y is measured on one end face of the crankshaft, and a coordinate system is established when the perpendicularity between the XY reference and the plane Y is within 5μm.

3. The method for measuring the runout of a crankshaft workpiece in three coordinates according to claim 1, characterized in that: In the above step 3), plane Y is taken as the Y-axis direction, the worktable is taken as the Z-axis direction, the XY reference is taken as the origin coordinate (0,0), and plane Y is taken as the projection plane to measure the shaft diameter of each gear. The measured coordinates of the shaft diameter of each gear are (X1, Z1)(X2, Z2)…, wherein the deviation in the X direction is △X, and the deviation in the Z direction is △Z; according to the values ​​of the measured coordinates of the shaft diameter of each gear (X1, Z1)(X2, Z2)…, first observe the value in the X direction. If the deviation △X in the X direction is large, adjust the floating support, observe the values ​​of the shaft diameter coordinates of each gear (X1, Z1)(X2, Z2)…, and calculate the values ​​of the shaft diameter coordinate deviations (△X1, △Z1)(△X2, △Z2)… of each gear until the deviation △X in the X direction is within 0.02㎜.

4. The method for measuring the runout of a crankshaft workpiece in three coordinates according to claim 3, characterized in that: Calculate the linear relationship of the journals of each gear, that is, When the linear relationship between the shaft diameters of each gear is within 0.02 mm and the support error is qualified, the crankshaft can be measured.

5. The method for measuring the runout of a crankshaft workpiece in three coordinates according to claim 3, characterized in that: When adjusting the floating support, first loosen the floating support, move the floating support left and right for adjustment, and then tighten the floating support.

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