A method for determining the positioning and sizing of automated assembly of an external part of a housing

Abstract

A method for determining the positioning size of the automatic assembly of the external part of the shell is completed by the interaction function between the robot and the operation table, the shell surface scanning, position data transmission and processing, external part grabbing and placing, and external part assembly positioning. According to the scanning data of the shell surface, the system accurately positions the placing position of the external part on the shell, so as to ensure the stability of the welding relative position and the good assembly size consistency. The shell scanning method is adopted to calculate the size of the external part, which is more accurate and stable compared with manual measurement, and when calculating the placing position of n groups of external parts, the first group of external part positions is taken as the reference, instead of the previous group of external part positions, so that the size deviation caused by error accumulation is reduced, and the assembly precision and size of the external part are ensured. Test verification shows that the assembly precision of the application is controlled within ±0.2mm, the assembly size is more stable, and the repair rate is reduced by 80% compared with manual assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal shell external component assembly, in particular to an external component automatic size setting method combining assembly-positioning welding and machine intelligence. BACKGROUND

[0002] The shell is mainly composed of a front head, a rear joint, a cylinder and external components. After the shell is formed, various external components need to be welded on the outer surface of the shell. The external components are functional components of the shell and are distributed on the outer circumference of the shell. The sizes and shapes of the external components are various, and there is generally one to several external components on the outer surface of the shell. The conventional welding method for the external components of the shell is to use manual setting. However, manual setting of the external components has the following problems:

[0003] 1. Poor welding precision of external components. In the layout process, there will be certain errors in the layout of the external components. When the metal worker assembles the external components according to the layout, there will be certain deviations between the visual assembly position of the external components and the layout position, and certain deviations will also occur during the assembly operation of the external components. The cumulative errors in each process result in a high over-dimension rate of the external components.

[0004] 2. High error rate due to pure manual operation. The types and sizes of the external components are various, and the entire layout, assembly and welding are completed by hand. In the case of many external components, the quality awareness, working state and working ability of the operator will obviously affect the assembly and welding dimensions of the external components, thereby increasing the error rate of the assembly and welding of the external components.

[0005] 3. Long operation time and low production efficiency. The entire assembly and welding process of the external components is operated manually, and the assembly precision of the external components is required to be high. The entire assembly process needs to be continuously adjusted and inspected for the position of the external components, which results in low production efficiency and cannot meet the research and development and batch production requirements of multi-variety metal shells.

[0006] The automatic size setting method for the external components of the shell uses an automatic setting system and a size calculation empirical formula to accurately control the assembly precision of the external components and meet the assembly size requirements. Compared with the manual setting method, the assembly precision is higher and the assembly size is more stable.

[0007] Huisheng (Nantong) Heavy Industry Co., Ltd. proposes a multifunctional special-shaped assembly and welding platform in the invention with the publication number CN116871802A, which can adjust the distance of C-shaped overturning to adapt to large-size special-shaped workpiece welding. However, for welding of small special-shaped parts with high precision, the distance control cannot guarantee the welding of large-size and high-precision workpieces.

[0008] Zhejiang Baiton Welding Technology Research Institute proposes an automatic welding equipment and method for H-shaped flat finned tube in the invention with publication number CN115846838A. The method can realize automatic feeding, automatic forming and automatic welding of flat elliptical finned tube. However, the invention can only be applied to the welding of workpieces with specific shapes and sizes, and cannot be applied to the welding of workpieces with variable shapes and sizes. SUMMARY

[0009] To overcome the deficiencies of unstable assembly size and poor assembly precision in the prior art, the present application provides a method for automatically setting the size of the external parts of a shell.

[0010] The specific implementation process of the present application is as follows:

[0011] Step 1: Obtain the parameters of the shell:

[0012] The parameters of the shell include the reference surface C0 of the external parts

[0013] Move the determined external part reference surface offset I0 from the initial scanning position C1 to one end of the shell to obtain the reference surface C0 of the external parts.

[0014] The initial scanning position C1 is located on the circumference at the end face of the one end of the shell.

[0015] Move the three-dimensional scanner tracker to the initial scanning position C1 to scan the shell and obtain the total length L of the shell.

[0016] Calculate the distance between the external part reference surface C0 and the initial scanning position C1 by formula (1).

[0017] I0 = [L-L0] x b1 (1)

[0018] In the formula:

[0019] I0 is the distance between the external part reference surface C0 and the scanning reference surface C1. L is the total length of the shell obtained by scanning. L0 is the minimum length allowed by the shell. b1 is the external part reference surface offset.

[0020] The external part reference surface offset refers to the offset per millimeter of the overgrown part when the total length L of the shell obtained by scanning is greater than the minimum length L0 allowed by the shell; b1 = 0.1-0.5mm.

[0021] Step 2: Determine the position of the center hole circle center of the reference group external parts in the XYZ coordinate system:

[0022] Take the first group of external parts W1 adjacent to the external part reference surface C0 as the reference group of external parts.

[0023] The specific process of determining the size of the reference group external component and the external component reference surface C0 is as follows:

[0024] The XYZ coordinate system of the shell takes the center of the end face where the initial scanning position C1 is located as the origin O of the XYZ coordinate system, takes the axial direction of the shell as the Y axis, takes the direction perpendicular to the Y axis in the horizontal plane as the X axis, and takes the direction perpendicular to the Y axis in the vertical plane as the Z axis. Taking the position of the origin O of the XYZ coordinate system as the reference, Y=0 of the origin O of the XYZ coordinate system is recorded as Y0.

[0025] The coordinate point Y of the center hole center of the reference group external component in the Y axis of the XYZ coordinate system of the shell is determined by formula (2) j1 :

[0026] Y j1 = Y0+I0+G (2)

[0027] In the formula, G is the distance between the external component reference surface C0 and the center hole center of the first group of external components W1 as the reference group external component, which is obtained by design.

[0028] According to the distance between the center hole center of the reference group external component and the axial line of the shell in the horizontal plane, the coordinate point X of the center hole center of the reference group external component in the X axis of the XYZ coordinate system is determined j1 .

[0029] According to the distance between the center hole center of the reference group external component and the axial line of the shell in the vertical plane, the coordinate point Z of the center hole center of the reference group external component in the X axis of the XYZ coordinate system is determined j1 .

[0030] Up to now, the position of the center hole center of the reference group external component in the XYZ coordinate system (Y j1 ; X j1 ; Z j1 ) is obtained.

[0031] Step 3, determine the coordinate point of each external component center hole center in the XYZ coordinate system:

[0032] The coordinate point Y of each external component center hole center in the Y axis of the XYZ coordinate system except the reference group external component is determined by formula (3) jn , n=2, 3, 4…n.

[0033] Y jn =Y j1 +(n-1)Yd

[0034] In the formula, Yd is the axial distance between the center hole centers of two adjacent external components

[0035] Determine the coordinate point X of the center of each external part center hole circle on the X axis in the XYZ coordinate system jn ; n is the number of the remaining external parts, n = 2, 3, 4 … n. X jn = X j1 .

[0036] Determine the coordinate point Z of the center of each external part center hole circle on the Z axis in the XYZ coordinate system jn ; n is the number of the remaining external parts, n = 2, 3, 4 … n. Z jn = Z j1 .

[0037] So far, the position of the center of each external part center hole circle in the XYZ coordinate system (Y jn ; X jn ; Z jn ) is obtained.

[0038] Step 4, assemble the positioning shell parts:

[0039] Open the external part clamping function of the assembly robot, grab the external part by the external part gripper of the assembly robot, and place the external part at the specified coordinate position according to the position coordinates of the center of each external part center hole circle in the XYZ coordinate system (Y jn ; X jn ; Z jn ) determined in step 3. Determine the welding robot and position each external part for welding.

[0040] So far, the assembly and positioning of all external parts of the shell are completed.

[0041] The technical key points of the present application are:

[0042] 1. External part reference line and algorithm for each group of external parts;

[0043] 2. Reference selection method of external part assembly size.

[0044] The present application completes shell surface scanning, position data transmission and processing, external part grabbing and placing, and external part assembly positioning through the interaction between the robot and the operation platform. According to the scanning data of the shell surface, the system accurately positions the placement position of the external part on the shell, thereby ensuring the stability of the welding relative position and the good consistency of the assembly size.

[0045] The present application calculates the size of the external part by scanning the shell, which is more accurate and stable than manual measurement. When calculating the placement position of n groups of external parts, the first group of external part position is taken as the reference, instead of the previous group of external part position, which reduces the size deviation caused by error accumulation, thereby ensuring the assembly precision and size of the external part.

[0046] In order to verify the effect of the present application, the test verifies that the external part setting is set by the automatic setting method of the shell external part, and one person can complete the entire external part setting operation, and the efficiency is increased by about 100% compared with manual setting, the assembly precision is controlled within ±0.2mm, the assembly size is more stable, and the repair rate is reduced by 80% compared with manual setting. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a top view of the distribution of the external part group on the surface of the shell.

[0048] Figure 2 is a schematic diagram of a certain shell radial section.

[0049] Figure 3 is a flowchart of the present application.

[0050] In the figure: 1. The first group of external parts; 2. The second group of external parts; 3. The third group of external parts. DETAILED DESCRIPTION

[0051] This embodiment is to set an external part W with a square cross section, a height gradient, and a central hole on the surface of a shell with a diameter D and a length L. The external part W is two groups; there are n groups, n=1, 2, 3, 4……n. Each group of external parts is respectively denoted as W1, W2, W3, ……Wn, and the first group of external parts W1 is the reference group of external parts.

[0052] Before setting, the external parts are set in the tray according to the conventional method, and the shell to be assembled is fixed on the positioner by using the four-jaw chuck. The shell surface is clean and has no obvious layered oxide scale. The external part material is carbon steel, and the shell material is high-strength steel. The specific implementation process is as follows:

[0053] Step 1, obtain the parameters of the shell:

[0054] The parameters of the shell include the reference surface C0 of the external part

[0055] Determine the initial scanning position C1; the initial scanning position C1 is located on the circumference at one end of the shell.

[0056] Move the three-dimensional scanner tracker to the initial scanning position C1, and scan the shell according to the conventional method to obtain the total length L of the shell.

[0057] Calculate the distance between the external part reference surface C0 and the initial scanning position C1 by formula (1).

[0058] I0=[L-L0]×б1 (1)

[0059] In the formula:

[0060] I0 is the distance between the outer part reference surface C0 and the scanning reference surface C1. L is the total length of the scanned shell. L0 is the minimum length of the shell. б1 is the outer part reference surface offset; the outer part reference surface offset refers to the offset per millimeter of the overhang when the total length L of the scanned shell is greater than the minimum length L0 of the shell; б1 = 0.1-0.5 mm.

[0061] At the determined initial scanning position C1, the reference surface C0 of the outer part is moved to the end of the shell by a determined outer part reference surface offset I0.

[0062] Step 2, determine the position of the center hole circle center of the reference group outer part in the XYZ coordinate system:

[0063] The first group of outer parts W1 adjacent to the outer part reference surface C0 are taken as the reference group outer parts.

[0064] The specific process of determining the size of the reference group outer part and the outer part reference surface C0 is as follows:

[0065] An XYZ coordinate system of the shell is established. The center of the end surface at the initial scanning position C1 is taken as the origin O of the XYZ coordinate system, the axial direction of the shell is taken as the Y axis, the direction perpendicular to the Y axis in the horizontal plane is taken as the X axis, and the direction perpendicular to the Y axis in the vertical plane is taken as the Z axis. Taking the position of the origin O of the XYZ coordinate system as the reference, the Y = 0 of the origin O of the XYZ coordinate system is recorded as Y0.

[0066] The coordinate point Y of the center hole circle center of the reference group outer part in the Y axis of the XYZ coordinate system is determined by formula (2) j1 .

[0067] Y j1 = Y0+I0+G (2)

[0068] In the formula, G is the distance between the outer part reference surface C0 and the center hole circle center of the first group of outer parts W1 as the reference group outer part, which is obtained by design requirements.

[0069] According to the distance between the center hole circle center of the reference group outer part and the shell axis in the horizontal plane, the coordinate point X of the center hole circle center of the reference group outer part in the X axis of the XYZ coordinate system is determined j1 .

[0070] According to the distance between the center hole circle center of the reference group outer part and the shell axis in the vertical plane, the coordinate point Z of the center hole circle center of the reference group outer part in the X axis of the XYZ coordinate system is determined j1 .

[0071] At this point, the position of the center hole circle center of the reference group outer part in the XYZ coordinate system (Yj1 ; X j1 ; Z j1 .

[0072] Step 3, determine the coordinate point of each external part center hole circle center in XYZ coordinate system:

[0073] Determine the coordinate point Y of each external part center hole circle center in Y axis of XYZ coordinate system except the reference group by formula (3) jn , n = 2, 3, 4…n.

[0074] Y jn = Y j1 + (n-1) Yd

[0075] In the formula, Yd is the axial distance between adjacent two external part center hole circle centers

[0076] Determine the coordinate point X of each external part center hole circle center in X axis of XYZ coordinate system jn ; n is the number of the remaining external parts, n = 2, 3, 4…n. X jn = X j1 .

[0077] Determine the coordinate point Z of each external part center hole circle center in Z axis of XYZ coordinate system jn ; n is the number of the remaining external parts, n = 2, 3, 4…n. Z jn = Z j1 .

[0078] So far, the position of each external part center hole circle center in XYZ coordinate system (Y jn ; X jn ; Z jn ) is obtained.

[0079] Step 4, assemble and position the external parts of the shell

[0080] Open the external part clamping function of the assembly robot, grab the external parts by the external part gripper of the assembly robot, and place the external parts at the specified coordinate position according to the position coordinates of each external part center hole circle center in XYZ coordinate system (Y jn ; X jn ; Z jn ) determined in step 3. Determine the welding robot and position the welding of each external part.

[0081] So far, the assembly and positioning work of all external parts of the shell is completed.

Claims

1. A method of determining the positioning dimensions for automated assembly of an exterior part of a housing, characterized by, The implementation process is: Step 1, obtaining the parameters of the shell: The parameters of the shell include the reference surface C0 of the external part; In the initial scanning position C1, move the determined external part reference surface offset I0 to one end of the shell to obtain the reference surface C0 of the external part; Step 2, determining the position of the center hole circle center of the reference group external part in the XYZ coordinate system: Take the first group of external parts W1 adjacent to the external part reference surface C0 as the reference group external part; The specific process of determining the size of the reference group external part and the external part reference surface C0 is: The coordinate point Y of the Y axis of the XYZ coordinate system of the shell is determined by formula (2) for the center hole of the center of the external part of the reference group j1 : Y j1 = Y0+ I0+ G (2) In the formula, G is the distance between the external part reference surface C0 and the center hole circle center of the first group of external parts W1 as the reference group external part, which is obtained by design; I0 is the distance between the external part reference surface C0 and the scanning reference surface C1; The position of the origin O of the XYZ coordinate system is taken as the reference, and the Y=0 of the origin O is recorded as Y0; The XYZ coordinate system of the shell is that the center of the end surface where the initial scanning position C1 is located is taken as the origin O of the XYZ coordinate system, the axial direction of the shell is taken as the Y axis, the direction perpendicular to the Y axis in the horizontal plane is taken as the X axis, and the direction perpendicular to the Y axis in the vertical plane is taken as the Z axis; According to the distance between the center of the center hole of the reference group of external parts and the axis of the shell at the horizontal plane of the design, the coordinate point X of the X axis of the center of the center hole of the reference group of external parts in the XYZ coordinate system is determined j1 ; The coordinate point Z of the X axis of the reference group outer part center hole circle center in the XYZ coordinate system is determined according to the distance between the reference group outer part center hole circle center and the shell axis in the vertical plane according to the design. j1 ; Thus, the position of the center of the hole of the external component of the reference group in the XYZ coordinate system (Y j1 ; X j1 ; Z j1 ) is obtained. Thus, the position of the center of the hole of the external component of the reference group in the XYZ coordinate system (Y j1 ; X j1 ; Z <000000 Step 3, determining the coordinate point of each external part center hole circle center in the XYZ coordinate system: The coordinate point Y of the Y axis of the center hole of each external component of the external components other than the reference group in the XYZ coordinate system is determined by formula (3) jn n = 2, 3, 4, … n Y jn = Y j1 +(n-1)Yd In the formula, Yd is the axial distance between the center hole circle centers of two adjacent external parts Determine the coordinate point X of the center of the center hole of each external part on the X axis of the XYZ coordinate system jn ; n is the number of the remaining external parts, n = 2, 3, 4 … n; X jn = X j1 ; determining the coordinate point Z of the center of the center hole of each external part on the Z axis of the XYZ coordinate system jn ; n is the number of the remaining external parts, n = 2, 3, 4, … n; Z jn = Z j1 ; Thus, the position of the center of the center hole of each external member in the XYZ coordinate system (Y jn ; X jn ; Z jn ) is obtained. Step 4, assembling and positioning the external parts of the shell: Opening the external part clamping function of the assembly robot, grabbing the external part by the external part gripper of the assembly robot, and placing the external part at the specified coordinate position according to the position coordinates (Y jn ;X jn ; Z jn ) of the center hole center of each external part in the XYZ coordinate system determined in step 3; determining a welding robot, and positioning and welding each external part; Thus, the assembly and positioning of all external parts of the shell are completed.

2. The method of determining the positioning and sizing of automated assembly of an external part of a housing according to claim 1, wherein, The initial scanning position C1 is located on the circumference of the end surface of the shell; Move the three-dimensional scanner tracker to the initial scanning position C1 to scan the shell and obtain the total length L of the shell; Calculate the distance between the external part reference surface C0 and the initial scanning position C1 by formula (1); I0=[L-L0]×б1 (1) In the formula: I0 is the distance between the external part reference surface C0 and the scanning reference surface C1; L is the total length of the shell obtained by scanning; L0 is the minimum length allowed by the shell; б1 is the external part reference surface offset.

3. The method of determining the positioning and sizing of automated assembly of an external part of a housing of claim 1, wherein, The external part reference surface offset refers to the offset per millimeter of the protruding part when the total length L of the shell obtained by scanning is greater than the minimum length L0 allowed by the shell; б1=0.1~0.5mm.

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