Device and method for measuring surface type and thickness of rocket engine cavity

Abstract

The invention discloses a rocket engine cavity surface type and thickness measuring device and method, and aims to solve the technical problems that the existing rocket engine cavity surface type and thickness measuring efficiency is low, and the rocket engine cavity surface type and thickness measuring task cannot be comprehensively and effectively completed. The device specifically comprises a first scanner, a second scanner, a three-coordinate displacement table and a rotating table, the first scanner and the second scanner are installed at the moving end of the three-coordinate displacement table, and the scanning directions of the first scanner and the second scanner are oppositely arranged. A measuring gap is arranged between the first scanner and the second scanner. The three-coordinate displacement table is used for driving the first scanner and the second scanner to move along the X axis, the Y axis and the Z axis at the same time. And the rotating table is arranged on the base of the three-coordinate displacement table, is positioned below the moving end of the three-coordinate displacement table, and is used for rotating a measured piece.

Description

Technical Field

[0001] The present invention relates to a measuring device and a measuring method for a rocket engine, and particularly to a device and a method for measuring the surface profile and thickness of a rocket engine cavity surface. Background Art

[0002] With the development of technology, 3D printing technology has gradually entered the traditional manufacturing industry. The parts produced by 3D printing have been integrated from several or dozens of parts produced by traditional technologies into one part. Nowadays, 3D printing technology has also been successfully applied to the manufacturing of rocket engines. However, manufacturing and inspection are inseparable. High-quality 3D printed parts require high-precision inspection technology. Therefore, it is of great significance to study and solve the problem of measuring the surface profile of the rocket engine cavity in 3D printing production.

[0003] At present, the methods for measuring the surface profile and thickness of the measured surface can generally be divided into contact measurement and non-contact measurement according to whether the probe contacts the measured surface. The most typical instrument in contact measurement is the stylus type coordinate measuring machine. Its probe needs to contact the measured surface, so it is easy to scratch the measured surface, and the detection takes a long time, resulting in very low measurement efficiency. Non-contact measurement means that the probe will not contact the measured surface, which can ensure that the measured surface will not be scratched, and has high measurement accuracy and fast measurement speed. Therefore, compared with contact measurement, non-contact measurement has great advantages. Traditional non-contact methods include time-of-flight method, structured light illumination method, interference method, etc. However, these methods cannot simultaneously meet the characteristics of non-contact, high-precision, and large stroke, resulting in the inability to comprehensively and effectively complete the measurement tasks of the surface profile and thickness of the rocket engine cavity. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and a method for measuring the surface profile and thickness of a rocket engine cavity to solve the technical problems of low measurement efficiency of the existing surface profile and thickness of the rocket engine cavity and the inability to comprehensively and effectively complete the measurement tasks of the surface profile and thickness of the rocket engine cavity.

[0005] To achieve the above purpose, the present invention provides a device for measuring the surface profile and thickness of a rocket engine cavity, which is characterized in that it includes a first scanner, a second scanner, a three-coordinate displacement stage, and a rotating stage;

[0006] The first scanner and the second scanner are installed on the mobile end of the three-coordinate displacement stage, and the scanning directions of the first scanner and the second scanner are set opposite to each other; there is a measurement gap between the first scanner and the second scanner;

[0007] The three-coordinate displacement stage is used to drive the first scanner and the second scanner to move simultaneously along the X-axis, Y-axis, and Z-axis;

[0008] The rotating table is arranged on the base of the three-coordinate displacement table and is located below the moving end of the three-coordinate displacement table for rotating the measured part.

[0009] Furthermore, it further includes a U-shaped connecting piece;

[0010] The U-shaped connecting piece has an opening vertically downward, and its top is fixedly connected to the moving end of the three-coordinate displacement table; the first scanner and the second scanner are fixedly installed on the inner walls at the lower ends of the two U-shaped walls of the U-shaped connecting piece, and the inner walls at the lower ends of the two U-shaped walls are parallel to each other.

[0011] Furthermore, the U-shaped connecting piece includes a horizontal telescopic rod and two vertical telescopic rods;

[0012] Both ends of the horizontal telescopic rod are horizontal telescopic ends;

[0013] The upper ends of the two vertical telescopic rods are respectively vertically connected to the two horizontal telescopic ends of the horizontal telescopic rod, and the lower ends of the two vertical telescopic rods are both vertical telescopic ends;

[0014] The first scanner and the second scanner are respectively fixedly installed on the inner walls of the two vertical telescopic ends of the two vertical telescopic rods.

[0015] Furthermore, the horizontal telescopic rod and the two vertical telescopic rods are all electric telescopic rods.

[0016] Furthermore, both the first scanner and the second scanner are line laser scanning sensors.

[0017] Furthermore, both the first scanner and the second scanner are surface laser scanning sensors.

[0018] Meanwhile, the present invention also provides a method for measuring the surface shape and thickness of a rocket engine cavity surface, using the above-mentioned device for measuring the surface shape and thickness of a rocket engine cavity surface, which is characterized in that it includes the following steps:

[0019] Step 1: Divide the inner cavity of the measured part into N layers from top to bottom, N≥3, and plan a measurement path for the N divided inner cavity layers; the measured part is an axisymmetric engine cavity;

[0020] Step 2: Place the measured part on the rotating table, start and adjust the three-coordinate displacement table so that the side wall of the measured part is within the measurement gap between the first scanner and the second scanner, and make the first scanner and the second scanner located on the measurement path of the first inner cavity layer;

[0021] Step 3: Start the rotary table to rotate the workpiece to be measured around the first scanner for one week. Push and scan the inner wall of the workpiece to be measured through the first scanner to obtain the first set of inner wall surface profile data. At the same time, the second scanner rotates around the outer wall of the workpiece to be measured for one week, and push and scan the outer wall of the workpiece to be measured through the second scanner to obtain the first set of outer wall surface profile data;

[0022] Step 4: Adjust the three-coordinate displacement table to move the first scanner and the second scanner to the measurement path of the next inner cavity layer, and repeat Step 3 to obtain the next set of inner wall surface profile data and the next set of outer wall surface profile data;

[0023] Step 5: Repeat Step 4 until the Nth set of inner wall surface profile data and the Nth set of outer wall surface profile data are obtained;

[0024] Step 6: Stitch the first set of inner wall surface profile data to the Nth set of inner wall surface profile data, and the first set of outer wall surface profile data to the Nth set of outer wall surface profile data to obtain the surface profile of the inner cavity of the workpiece to be measured and the side wall thickness of the workpiece to be measured.

[0025] Advantages of the present invention:

[0026] 1. The present invention combines two scanners (i.e., the first scanner and the second scanner), a three-coordinate displacement table, and a rotary table. The three-coordinate displacement table realizes the movement of the two scanners in three spatial directions of the X-axis, Y-axis, and Z-axis, and the rotary table realizes the circumferential rotation of the workpiece to be measured between the two scanners, so as to perform layer-by-layer push and scan on the inner cavity surface profile and thickness of the engine, realize the acquisition of the inner cavity surface profile and thickness data of the engine. Neither of the two scanners needs to contact the measured surface. At the same time, it can also realize large-stroke measurement to comprehensively and effectively measure the inner cavity surface profile of the engine. The entire measurement process does not require manual participation, saving labor and improving measurement efficiency.

[0027] 2. The present invention uses a U-shaped connecting piece to install the first scanner and the second scanner, thereby forming a measurement gap between the first scanner and the second scanner, and the U-shaped connecting piece is set to be composed of a transverse telescopic rod and two vertical telescopic rods. On the one hand, it realizes a large stroke, and on the other hand, it can be adjusted horizontally and vertically according to workpieces of different specifications, improving the applicability of the measuring device.

[0028] 3. The present invention uses a line laser scanning sensor or a surface laser scanning sensor for measurement, which greatly improves the measurement accuracy compared with the prior art.

[0029] 4. The present invention drives the workpiece to be measured to rotate between the two scanners through the rotary table to realize the relative movement between the measured surface and the scanner, reducing the movement of the scanner, greatly reducing the movement of the scanner during the measurement process, improving the measurement efficiency and ensuring the measurement accuracy.

[0030] 5. The present invention can automate the measurement of the inner cavity surface shape and thickness of a rocket engine, quickly and effectively measure the inner cavity surface shape and thickness of the rocket engine, and timely adjust the 3D printing parameters according to the measurement data of the inner cavity surface shape and thickness of the rocket engine, thereby improving the production efficiency of 3D printing of the rocket engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the schematic diagram of the laser triangulation method measurement of the laser scanning sensor adopted in the embodiment of the present invention;

[0032] Figure 2 is the schematic structural diagram of an embodiment of a device for measuring the surface shape and thickness of a rocket engine cavity of the present invention;

[0033] Figure 3 is the schematic structural diagram when measuring the surface shape and thickness of a rocket engine cavity by adopting the embodiment of the present invention;

[0034] Figure 4 is the schematic structural diagram of the U-shaped connecting piece in the embodiment of the present invention;

[0035] Figure 5 is the planned measurement path diagram when measuring the surface shape and thickness of an axisymmetric engine cavity by adopting the embodiment of the present invention.

[0036] Reference Numerals in the Drawings:

[0037] 01 - Laser, 02 - Measured Surface, 03 - Photographing Device, 04 - Imaging Lens, 05 - Reference Plane, 06 - Shaping Lens;

[0038] 1 - First Scanner, 2 - Second Scanner, 3 - Three-Coordinate Displacement Table, 4 - Rotary Table, 5 - Measured Part, 6 - U-Shaped Connecting Piece, 61 - Horizontal Telescopic Rod, 62 - Vertical Telescopic Rod. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] The first scanner 1 and the second scanner 2 in the embodiments of the present invention mainly use a laser scanning sensor for measurement. The measurement principle of the laser scanning sensor is the laser triangulation method, as Figure 1As shown in the figure, for the laser triangulation method, it generally includes at least a laser 01, a measured surface 02, and a photographing device 03 (usually a CCD). The laser 01, the measured surface 02, and the photographing device 03 form a triangle. BD is the object distance of the imaging system, and its length is a; DF is the image distance of the imaging system, and its length is b; β is the angle between the laser beam and the optical axis of the imaging lens 04; BF is the optical axis of the imaging lens 04; AC is perpendicular to BF, and AC intersects BF at C; h is the offset distance between the measured surface 02 and the reference surface 05; EF is the distance that the light spot moves on the CCD target surface, and its length is x. The laser emitted by the laser 01 is vertically irradiated on the measured surface 02 through the shaping lens 06. When the laser irradiates at point B, the scattered light spot is focused on point F on the CCD target surface through the imaging lens 04; when the measured surface 02 is offset upward by h relative to the reference surface 05, the laser irradiates at point A, and at this time the scattered light spot is focused on point E on the CCD target surface through the imaging lens 04. According to the geometric relationship, it can be known that triangle ACD is similar to triangle EFD, and the following formula can be obtained:

[0041]

[0042] Then, the offset distance of the measured surface 02 relative to the reference surface 05, that is, the actual height h of the measured surface 02, can be obtained as:

[0043]

[0044] According to the above measurement principle, using a laser scanner to scan and measure the inner cavity surface shape of the engine, the surface shape information of the inner cavity of the engine can be obtained.

[0045] An embodiment of the present invention provides a device for measuring the surface shape and thickness of a rocket engine cavity, in combination with Figures 2 to 4 As shown in the figure, the measurement device includes a first scanner 1, a second scanner 2, a three-coordinate displacement stage 3, and a rotary table 4;

[0046] The first scanner 1 and the second scanner 2 are installed on the mobile end of the three-coordinate displacement stage 3 through a U-shaped connector 6. The three-coordinate displacement stage 3 is used to drive the first scanner 1 and the second scanner 2 to move along the X-axis, Y-axis, and Z-axis simultaneously. The U-shaped connector 6 has an opening facing vertically downward, and its top is fixedly connected to the mobile end of the three-coordinate displacement stage 3. Specifically, the U-shaped connector 6 includes a horizontal telescopic rod 61 and two vertical telescopic rods 62. Both ends of the horizontal telescopic rod 61 are horizontal telescopic ends. The upper ends of the two vertical telescopic rods 62 are respectively perpendicularly connected to the two horizontal telescopic ends of the horizontal telescopic rod 61. The lower ends of the two vertical telescopic rods 62 are both vertical telescopic ends. The first scanner 1 and the second scanner 2 are respectively fixedly installed on the inner walls of the two vertical telescopic ends of the two vertical telescopic rods 62, and the scanning directions of the first scanner 1 and the second scanner 2 are arranged oppositely, so that a measurement gap is formed between the first scanner 1 and the second scanner 2. In this way, the distance between the first scanner 1 and the second scanner 2, that is, the size of the measurement gap, can be controlled by the horizontal telescopic rod 61, and the lengths of the two vertical telescopic rods 62 can also be controlled according to the measurement depth. Among them, the horizontal telescopic rod 61 and the two vertical telescopic rods 62 are both electric telescopic rods. The rotating table 4 is arranged on the base of the three-coordinate displacement stage 3 and is located below the opening of the U-shaped connector 6 for rotating the measured part 5. Both the first scanner 1 and the second scanner 2 are line laser scanning sensors or surface laser scanning sensors.

[0047] The using steps are as follows:

[0048] Step 1: Divide the inner cavity of the measured part 5 into N layers from top to bottom, where N≥3, and plan the measurement paths for the N divided inner cavity layers. The measured part 5 is an axisymmetric engine cavity.

[0049] Step 2: Place the measured part 5 on the rotating table 4, start and adjust the three-coordinate displacement stage 3 so that the side wall of the measured part 5 is located within the measurement gap between the first scanner 1 and the second scanner 2, and make the first scanner 1 and the second scanner 2 located on the measurement paths of the first layer inner cavity.

[0050] Step 3: Start the rotating table 4 to rotate the measured part 5 around the first scanner 1 for one week. Push-scan the inner wall of the measured part 5 through the first scanner 1 to obtain the first set of inner wall surface type data. At the same time, the second scanner 2 rotates around the outer wall of the measured part for one week, and push-scan the outer wall of the measured part 5 through the second scanner 2 to obtain the first set of outer wall surface type data.

[0051] Step 4: Adjust the three-coordinate displacement stage 3 to move the first scanner 1 and the second scanner 2 to the measurement paths of the next layer inner cavity, and repeat Step 3 to obtain the next set of inner wall surface type data and the next set of outer wall surface type data.

[0052] Step 5: Repeat Step 4 until the Nth set of inner wall surface data and the Nth set of outer wall surface data are obtained;

[0053] Step 6: Concatenate the first set of inner wall surface data to the Nth set of inner wall surface data and the first set of outer wall surface data to the Nth set of outer wall surface data to obtain the surface profile of the inner cavity of the workpiece 5 and the side wall thickness of the workpiece 5.

[0054] Specifically, before the rocket engine inner cavity surface profile and thickness measuring device works, it is necessary to complete the planning of the measurement path. The workpiece 5 is a circular axisymmetric structure as a whole. For the surface profile structure of the axisymmetric engine inner cavity of the workpiece 5, the movement path of the line laser probe as shown in Figure 5 can be planned. Assume that N layers of data need to be collected to obtain all the data. During operation, first, the three-coordinate displacement stage 3 moves the first scanner 1 and the second scanner 2 to the first layer of detectable area, starts the rotary table 4, and the workpiece 5 rotates to complete the push-scan acquisition of the first layer of data; then, the three-coordinate displacement stage 3 moves the first scanner 1 and the second scanner 2 to the second layer of detectable area, starts the rotary table 4, and the workpiece 5 rotates to complete the acquisition and concatenation of the second layer of data; and so on until the inner and outer surface profile data of the Nth layer of the engine are obtained. Finally, the surface profile and thickness of the engine cavity can be obtained through the inner and outer surface profile data.

[0055] From the description of the above embodiments, those skilled in the art can clearly understand that for the convenience and conciseness of description, only the above division of each functional module is used as an example. In actual applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.

[0056] The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A measuring device for the surface shape and thickness of a rocket engine chamber, characterized in that: It includes a first scanner (1), a second scanner (2), a three - coordinate displacement stage (3) and a rotary table (4); The first scanner (1) and the second scanner (2) are installed on the mobile end of the three - coordinate displacement stage (3), and the scanning directions of the first scanner (1) and the second scanner (2) are set oppositely; there is a measurement gap between the first scanner (1) and the second scanner (2); The three - coordinate displacement stage (3) is used to drive the first scanner (1) and the second scanner (2) to move simultaneously along the X - axis, Y - axis and Z - axis; The rotary table (4) is arranged on the base of the three - coordinate displacement stage (3) and is located below the mobile end of the three - coordinate displacement stage (3) for rotating the measured part (5).

2. The rocket engine cavity surface shape and thickness measuring device according to claim 1, characterized in that: It also includes a U - shaped connecting piece (6); The U - shaped connecting piece (6) has an opening vertically downward, and its top is fixedly connected to the mobile end of the three - coordinate displacement stage (3); the first scanner (1) and the second scanner (2) are fixedly installed on the inner walls of the lower ends of the two U - shaped walls of the U - shaped connecting piece (6), and the inner walls of the lower ends of the two U - shaped walls are parallel to each other.

3. The rocket engine chamber surface shape and thickness measuring device according to claim 2, characterized in that: The U - shaped connecting piece (6) includes a transverse telescopic rod (61) and two vertical telescopic rods (62); Both ends of the transverse telescopic rod (61) are transverse telescopic ends; The upper ends of the two vertical telescopic rods (62) are respectively perpendicularly connected to the two transverse telescopic ends of the transverse telescopic rod (61), and the lower ends of the two vertical telescopic rods (62) are both vertical telescopic ends; The first scanner (1) and the second scanner (2) are respectively fixedly installed on the inner walls of the two vertical telescopic ends of the two vertical telescopic rods (62).

4. The rocket engine cavity surface shape and thickness measuring device according to claim 3, characterized in that: The transverse telescopic rod (61) and the two vertical telescopic rods (62) are all electric telescopic rods.

5. The rocket engine cavity surface shape and thickness measuring device according to any one of claims 1-4, characterized in that: Both the first scanner (1) and the second scanner (2) are line laser scanning sensors.

6. The rocket engine cavity surface shape and thickness measuring device according to any one of claims 1-4, characterized in that: Both the first scanner (1) and the second scanner (2) are surface laser scanning sensors.

7. A method for measuring the surface shape and thickness of a rocket engine chamber, based on the rocket engine chamber surface shape and thickness measuring device according to any one of claims 1-6, characterized in that, It includes the following steps: Step 1: Divide the inner cavity of the measured part (5) into N layers from top to bottom, where N≥3, and plan the measurement paths for the N divided inner cavity layers; the measured part (5) is an axisymmetric engine cavity; Step 2: Place the measured part (5) on the rotary table (4), start and adjust the three - coordinate displacement stage (3) so that the side wall of the measured part (5) is located within the measurement gap between the first scanner (1) and the second scanner (2), and make the first scanner (1) and the second scanner (2) located on the measurement paths of the first - layer inner cavity; Step 3: Start the rotary table (4) to make the measured part (5) rotate one week around the first scanner (1), push - scan the inner wall of the measured part (5) through the first scanner (1) to obtain the first set of inner - wall surface profile data, and at the same time, the second scanner (2) rotates one week around the outer wall of the measured part, push - scan the outer wall of the measured part (5) through the second scanner (2) to obtain the first set of outer - wall surface profile data; Step 4: Adjust the three - coordinate displacement stage (3) to move the first scanner (1) and the second scanner (2) to the measurement paths of the next - layer inner cavity, and repeat Step 3 to obtain the next set of inner - wall surface profile data and the next set of outer - wall surface profile data; Step 5: Repeat Step 4 until the Nth set of inner wall surface data and the Nth set of outer wall surface data are obtained; Step 6: Concatenate the first set of inner wall surface data to the Nth set of inner wall surface data and the first set of outer wall surface data to the Nth set of outer wall surface data to obtain the surface profile of the inner cavity of the workpiece (5) and the side wall thickness of the workpiece (5).

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