A method for measuring the curvature of large shaft and hole parts

Abstract

The present invention discloses a method for measuring the offset of large shaft and hole parts. This method utilizes a laser head, a laser fixture, a positioning hole plate, an imaging screen, a camera, and an image analysis computer. The method utilizes the linearity of the laser light path to reflect the center offset caused by shaft and hole bending as the displacement of the imaging film laser from a reference point. The camera detects the light spot and a computer analyzes the actual center point to calculate the actual curvature. This method is low-cost and highly accurate, and can be installed and disassembled according to the actual environment of shaft and hole parts, resolving the high cost and low accuracy of existing manual inspections.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical structure curvature measurement, and in particular to a method for measuring the curvature of large shafts and hole-type parts. Background Art

[0002] Today's shipbuilding and heavy equipment applications require increasingly high precision for large shafts and bores. However, in actual production and on-site machining, measuring the curvature error of large spindles and bores is difficult, and there is no reliable method to accurately calculate curvature error. Large spindles or bores are often several meters or even tens of meters long. Some bores are discontinuous, but the centers of the bores must be aligned as closely as possible. During operation, machining errors can occur due to the length of these shafts and bores, leading to significant curvature errors. These errors are significant and often significantly impact accuracy. Due to their large size and the small actual curvature measurements, typically on the millimeter scale, measuring and compensating for curvature errors caused by machining errors is challenging. Traditionally, professional surveyors have used optical techniques, visual observation, and manual measurement to measure curvature. However, this method is labor-intensive and lacks effective accuracy, significantly impacting both machining accuracy and cost.

[0003] The existing curvature measurement devices and methods are only suitable for measuring the curvature of large, solid parts and are not suitable for measuring the curvature of parts with holes or other non-continuous parts. Therefore, this patent designs a curvature measurement method for shaft-hole parts and other non-continuous parts. This method uses a simple and accurate device, and is a reusable method for measuring the curvature of shaft-hole parts, replacing existing manual measurement methods and some curvature measurement methods available on the market. Summary of the Invention

[0004] The purpose of the present invention is to address the defects of the existing technology and provide a high-precision method and device for measuring the curvature of large shaft and hole parts. This method solves the shortcomings of the existing measurement methods, such as low measurement accuracy, cumbersome operation, large manpower requirements, and inability to measure quickly and automatically, and greatly improves the accuracy of curvature compensation during the processing of large workpieces.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for measuring the offset of large shaft and hole parts, characterized by comprising the following steps:

[0007] Step 10: A first positioning hole plate is set at the front end of the part to be measured, a second positioning hole plate is set in the middle position, and an imaging screen is set at the end. The first positioning hole plate, the second positioning hole plate, the imaging screen and the axis of the part to be measured are in the same plane. The first positioning hole on the first positioning hole plate, the second positioning hole on the second positioning hole plate and the center point of the imaging screen are at the same distance from the surface of the part to be measured;

[0008] Step 20: Emit a laser along the axis of the part to be measured, and adjust the laser light path so that it passes through the first positioning hole and the second positioning hole in sequence and falls on the imaging screen;

[0009] Step 30: Capture the position of the laser spot on the imaging screen, measure the distance from the laser spot to the center point, and obtain the offset of the end of the part to be measured in that direction;

[0010] Step 40: Repeat the above steps at four orthogonal positions of the part to be measured, namely, up, down, left, and right, to obtain the offset of the part to be measured in four different directions.

[0011] Furthermore, when the part to be tested is a shaft part, it also includes:

[0012] Step 50: Obtain the offset of the part to be measured at the second positioning hole plate by using the triangle similarity theorem;

[0013] Step 60: According to formula Y max =8pl 3 ÷(384EI)=pl 3 ÷(48EI) to calculate the curvature of the part to be tested, where Y max is the curvature of the spindle part, p is the sum of the standard values ​​of each concentrated load, E is the elastic modulus of the part to be measured, I is the interface inertia of the part to be measured, and l is the offset of the part to be measured at the second positioning hole plate.

[0014] Furthermore, the first positioning hole plate and the second positioning hole plate are fixed on the part to be measured by magnetic adsorption of the positioning surfaces.

[0015] Furthermore, in step 30, the distance from the laser spot to the center point on the imaging screen is collected and calculated by a camera and an image processing computer.

[0016] Compared with the existing technology, the present invention has the following advantages: 1. This method is easy and flexible to measure, with a simple and easily disassembled structure, a small size, and convenient portability and storage, making it adaptable to different measurement situations in industrial sites. 2. This method can directly obtain measurement results through spot image acquisition and host computer analysis, making the measurement process convenient and fast. 3. This method uses a multi-directional measurement method to accurately obtain the actual curvature direction and the curvature component value in any direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of measuring the curvature of a large shaft according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of measuring the deviation of a hole-type part according to the second embodiment of the present invention;

[0019] Figure 3 Schematic diagram of obtaining a reference coaxial line by orthogonally forming four groups of laser beams in the second embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the structure of the first positioning hole plate of the present invention;

[0021] Figure 5 This is a schematic diagram of the imaging screen structure of the present invention;

[0022] Among them: 1-first positioning hole plate, 2-second positioning hole plate, 3-imaging screen, 4-laser head, 5-laser spot, 6-camera, 7-computer, 8-spindle part, 9-collimated laser light path, 10-first processing hole, 11-second processing hole, 12-third processing hole, 13-axis of hole-type parts, 101-first positioning hole, 201-second positioning hole, 301-center point, 801-axis of spindle part. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0024] Example 1:

[0025] This embodiment is a method for measuring the curvature of a large spindle part, comprising the following steps:

[0026] Step 10: Figure 4 As shown, the first positioning hole plate 1 is provided with a first positioning hole 101, and the second positioning hole plate 2 has the same structure as the first positioning hole plate 1, and is provided with a second positioning hole 201. The first positioning hole plate 1, the second positioning hole plate 2, and the imaging screen 3 are respectively installed at the starting end, the middle position, and the end of the spindle part 8, as shown in FIG. Figure 1 As shown, it is positioned by a high-precision positioning surface and fixed to the outer cylindrical surface of the spindle part 8 by magnetic adsorption. The positioning surface must ensure that the distance between the first positioning hole 101, the second positioning hole 201 and the center point 301 on the imaging screen 3 and the outer cylindrical surface of the spindle part 8 is constant and accurate, and the connecting line of the first positioning hole plate 1 and the second positioning hole plate 2 is as parallel as possible to the spindle part axis 801.

[0027] Step 20: Adjust the position of the laser head 4 so that the laser light emitted by it can simultaneously pass through the first positioning hole 101 and the second positioning hole 201 and fall on the imaging screen 3. At this time, the collimated laser light path 9 should be approximately parallel to the spindle component axis 801.

[0028] Step 30: Image acquisition The industrial camera 6 faces the imaging screen 3 from the side and is fixed to the ground through a fixing frame. The camera 6 can capture the position of the laser spot 5 on the imaging screen 3. Figure 5 As shown, the center of the imaging screen 3 is marked, and this center point 301 is located at the same position as the positioning hole on the positioning hole plate. The camera 6 and image processing computer 7 collect and calculate the distance from the laser spot 5 on the imaging screen 3 to the center point 301, thereby determining the offset of the spindle component 8 at the end relative to the intended spindle component axis 801.

[0029] Step 40: Repeat the above steps, measuring in four orthogonal directions: up, down, left, and right. This will yield four sets of laser beams approximately parallel to the spindle axis 801. The orthogonal intersection line formed by these four beams is the spindle axis 801. Simultaneously, using the projection method described in the above steps, the offset distances of the spindle component 8 from the spindle axis 801 in four different directions can be determined.

[0030] Step 50: Obtain the offset of the spindle part 8 at the second positioning hole plate 2 by using the triangle similarity theorem;

[0031] Step 60: According to formula Y max =8pl 3 ÷(384EI)=pl 3 ÷(48EI) to calculate the curvature of the spindle part 8, where Y max is the curvature of the spindle part 8, p is the sum of the standard values ​​of each concentrated load, E is the elastic modulus of the spindle part 8, I is the interface moment of inertia of the spindle part 8, and l is the offset of the spindle part 8 at the second positioning hole plate 2.

[0032] As can be seen from the above technical solution, this measuring device reflects the curvature of the spindle component 8 by measuring the distance the positioning orifice plate descends or ascends. This change in curvature of the spindle component 8 causes the laser spot 5, imaged by the high-precision collimated laser light path 9 on the imaging screen 3, to shift, creating a distance from the center point 301. The laser spot 5 is captured by a camera 6, and computer 7 analyzes the image to determine the spot offset distance. The laser offsets measured by these four devices are used to calculate the horizontal and vertical curvature components of the spindle component 8, ultimately measuring the curvature.

[0033] Example 2:

[0034] This embodiment is a method for measuring the offset of hole parts, including the following steps:

[0035] Step 10: Use the same first positioning hole plate 1, second positioning hole plate 2, and imaging screen 3 as in the first embodiment. Figure 2 As shown, the first positioning hole plate 1, the second positioning hole plate 2, and the imaging screen 3 are respectively installed on the left end surfaces of the first processing hole 10, the second processing hole 11, and the third processing hole 12, and are positioned by high-precision positioning surfaces and fixed to the inner hole surfaces by magnetic adsorption. The positioning surfaces must ensure that the distances between the first positioning hole 101, the second positioning hole 201, and the center point 301 on the imaging screen 3 and the axis of each processing hole are constant and precise.

[0036] Step 20: Adjust the position of the laser head 4 so that the laser light emitted by it can pass through the first positioning hole 101 and the second positioning hole 201 at the same time and fall on the imaging screen 3. At this time, the collimated laser light path 9 should be approximately parallel to the axis 13 of the hole-like component.

[0037] Step 30: The image acquisition camera 6 faces the imaging screen 3 from the side and is fixed to the ground through a fixing frame. The camera 3 can capture the position of the laser spot 5 on the imaging screen 3. Figure 5 As shown, the center of imaging screen 3 is marked, and this center point 301 is located at the same position as the positioning hole on the positioning hole plate. By using camera 6 and image processing computer 7 to collect and calculate the distance from laser spot 5 on imaging screen 3 to center point 301, the offset of third machining hole 12 relative to the hole-like component axis 13 defined by the first and second machining holes can be determined.

[0038] Step 40: Repeat the above steps, measuring in four orthogonal directions: up, down, left, and right of the machined hole. This will yield four sets of laser beams parallel to the hole component axis 13. The orthogonal intersection line formed by these four beams is the hole component axis 13. Simultaneously, using the projection method described in the above steps, the offset distances of the third machined hole 12 from the hole component axis 13 in four different directions can be obtained.

[0039] Since the distance between the first processing hole 10 and the second processing hole 11 is far enough, the error of the positioning plate installation and the error of the laser adjustment will not be amplified. Therefore, the laser light path can be used as one of the references for the axis 13 of the hole-type part.

[0040] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to enable relevant persons familiar with this technology to implement them accordingly. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for measuring the offset of large shaft and hole parts, characterized in that: The steps include: Step 10: a first positioning hole plate (1) is arranged at the front end of the part to be measured, a second positioning hole plate (2) is arranged at the middle position, and an imaging screen (3) is arranged at the end, wherein the first positioning hole plate (1), the second positioning hole plate (2), the imaging screen (3) and the axis (4) of the part to be measured are in the same plane, and the first positioning hole (101) on the first positioning hole plate (1), the second positioning hole (201) on the second positioning hole plate (2) and the center point (301) on the imaging screen (3) are at the same distance from the surface of the part to be measured; Step 20: Emitting laser light along the axis of the part to be measured, and adjusting the laser light path so that the laser light just passes through the first positioning hole (101) and the second positioning hole (201) in sequence and then falls on the imaging screen (3); Step 30: Acquire the position of the laser spot (5) on the imaging screen (3), measure the distance from the laser spot (5) to the center point (301), and obtain the offset of the end of the part to be measured relative to the axis of the part to be measured; Step 40: Repeat the above steps at four orthogonal positions of the part to be measured, namely, up, down, left, and right, to obtain the offset of the part to be measured in four different directions.

2. The method for measuring the offset of large shafts and hole parts according to claim 1, characterized in that: When the part to be tested is a shaft part, it also includes: Step 50: Obtain the offset of the part to be measured at the second positioning hole plate (2) by using the triangle similarity theorem; Step 60: According to formula Y max =8pl 3 ÷(384EI)=pl 3 ÷(48EI) to calculate the curvature of the part to be tested, where Y max is the curvature of the spindle part, p is the sum of the standard values ​​of each concentrated load, E is the elastic modulus of the part to be measured, I is the interface inertia of the part to be measured, and l is the offset of the part to be measured at the second positioning hole plate.

3. The method for measuring the offset of large shafts and hole parts according to claim 1, characterized in that: The first positioning hole plate (1) and the second positioning hole plate (2) are fixed on the part to be measured by magnetic adsorption of the positioning surfaces.

4. The method for measuring the offset of large shafts and hole parts according to claim 1, characterized in that: In step 30, the distance from the laser spot (5) to the center point (301) on the imaging screen (3) is collected and calculated by the camera (6) and the image processing computer (7).

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