NL2031936B1

NL2031936B1 - Path development method for multi-pass linear cladding on curved surface

Info

Publication number: NL2031936B1
Application number: NL2031936A
Authority: NL
Inventors: Hu Yuecheng; Yang Xiaohong; Chu Xu; Jiang Qianlei; Chen Yuan
Original assignee: Jinhua Polytechnic
Priority date: 2021-09-23
Filing date: 2022-05-19
Publication date: 2023-06-29
Also published as: CN113909495A; CN113909495B; NL2031936A

Abstract

Disclosed is a path development method for multi-pass linear cladding on a curved surface. Work Visual software configured in a KUKA robot is used to carry out program development, a substrate has a length and a width of 50 mm, respectively, the curved surface has heights of a lowest point and a highest point of 137 mm and 150 mm, respectively, and a matrix material is low-carbon steel. Since it is simply required to obtain a transverse displacement value and a longitudinal displacement value of each pass, with reference to FIG. 3, simply a two-dimensional contour of the curved surface lO is required to be reconstructed through AutoCAD software. The path development methodcladding on can use the Worlesual software configured in the KUKA robot to rapidly carry out manual programming without special additive manufacturing slicing and track planning software, to obtain a compleX multi-pass linear cladding track program.

Description

PATH DEVELOPMENT METHOD FOR MULTI-PASS LINEAR CLADDING

ON CURVED SURFACE

TECHNICAL FIELD

[DI] The present invention relates to the related technical field of laser additive manufacturing, and in particular to a path development method for multi-pass linear cladding on a curved surface.

BACKGROUND ART

[02] The metal components are the main structural parts in industrial production, of which the curved surfaces are the most common component structures. However, owing to the large bearing force and the serious wear in work, the curved surfaces are highly possible to fail in the service processes. Therefore, it is necessary to repair or strengthen the surfaces of the curved components to improve the bearing capacity of the components.

[03] In consideration of the low processing precision, the low production efficiency, etc. of the manual cladding, the digital automatic additive manufacturing technology has gradually replaced the conventional manual welding repair. Due to the high work flexibility, as the most typical technologies in application, the robot based automatic additive repair technologies, such as the laser cladding and the arc additive manufacturing, are widely used in enterprise production currently.

[04] When the robot is used for automatic processing, it 1s required to plan the walking track of the robot first. Compared to the plane, the curved surface is relatively more complex, which also brings difficulties to the walking processing of the robot. For planning the walking track of the curved surface, in general, the common method includes: using the automatic software for slicing and forming the automatic track. The method features the high automation degree and the precise track formation. However, the method also features the obvious disadvantages. First, the specialized software is required, which is costly generally, with a price of tens of thousands to hundreds of thousands Yuan, thereby greatly increasing the cost of apparatus running. Second, generally, it is required to reconstruct the three-dimensional structure of the part to be processed in the software to form the track, resulting in the high technical difficulty.

[05] Therefore, there is a need for a method with the low cost and the low technical difficulty to plan the cladding track.

[06] It is possible to use the program configured in the robot for programming, which is intuitive. However, it is difficult to compile the complex programs. To address the problem, the KUKA robot is configured with the WorkVisual software, thereby greatly facilitating the robot programming. Therefore, the present invention primarily uses the Work Visual configured in the KUKA to compile the cladding track of the curved surface.

[07] For cladding the curved surface, the general cladding track is along the curved surface for cladding, that is, the curved cladding path is provided. However, due to the rapid heating and cooling during cladding processing, the thermal stress is very likely to be formed in the alloy layer formed through the additive manufacturing. Especially during the multi-layer cladding, with the cladding passes and the number of layers increased, the thermal stress in the alloy layer is increased rapidly, which leads to the high possibility of alloy cracking and unavailability. If a “cross” type cladding layer is formed between the upper layer and the lower layer, the different stress distribution states between the upper layer and the lower layer can be conducive to offsetting the stress to a large extent, thereby reducing the cracking. Therefore, it is required to compile the multi-pass linear cladding path of the curved surface. However, in the multi-pass linear cladding process, since a large number of cladding passes are provided, it is impossible to determine the starting running point of each of the passes in a manual point determining manner. The best solution is to automatically form the walking track of the multi-pass cladding after the cladding starting point is determined. In the cladding process, angle change of the cladding head on the Y-Z plane is caused, and the angle of the cladding head needs to be adjusted correspondingly after each cladding pass is completed. Therefore, the angle between the cladding head and the matrix during the processing remains basically consistent, thereby ensuring the consistency and stability of forming the cladding layer at all parts of the curved surface. Just owing to the angle change of the cladding head, the coordinate system of the robot system is constantly changed in the working process, and the position information of each of the passes is difficult to determine. Therefore, it is almost impossible to carry out the manual track programming, which greatly limits the development of the robot based automatic cladding process and the control of the alloy cracks generated during the additive manufacturing.

SUMMARY

[08] Aiming at the defects in the prior art, an objective of the present invention is to provide a path development method for multi-pass linear cladding on a curved surface.

[09] To realize the objective described above, the present invention provides a path development method for multi-pass linear cladding on a curved surface. The method uses AutoCAD to reconstruct contour information of a curved surface of a metal component, to obtain position movement information of a cladding head of each pass, and then uses Work Visual software configured in a KUKA robot, to carry out automatic program development. The method includes:

[10] S1: obtaining size information of the curved surface of the metal component to be processed, and using the AutoCAD software to reconstruct two-dimensional contour information of the curved surface of the metal component;

[11] S2: then evenly dividing the curved surface into corresponding parts in the

AutoCAD after determining cladding passes and a movement distance of each of the passes, the parts being the same as the cladding passes; 12] S3: using the AutoCAD to measure and obtain transverse displacement and longitudinal displacement between any two adjacent passes;

[13] S4: using a relative motion statement SLIN REL to compile, in the

WorkVisual according to the obtained transverse displacement and longitudinal displacement between every two adjacent passes, a position movement value of the cladding head of each of the passes, a statement name being SLIN REL{Y,Z,C},

[14] where Y denotes a transverse displacement value, Z denotes a longitudinal displacement value, C denotes an angle information value of the cladding head rotating on a Y-Z plane while moving in Y and Z directions every time of pass change;

[15] in the above, the movement distance? of each of the passes being Y?+Z%; and

[16] S5: carrying out trial running on a program, and adjusting, in ratio according to an error ratio value of a running result, a transverse displacement value and a longitudinal displacement value of each of the passes, until a required walking precision requirement is met.

[17] Optionally, in step S2, the movement distance of each of the passes is calculated as follows:

[18] (1) determining a lapping rate between two adjacent passes and a single-pass cladding width of an apparatus; and

[19] (2) multiplying the single-pass cladding width of the apparatus by (1-lapping rate), to calculate the movement distance of each of the passes.

[20] Optionally, in step S2, the cladding passes are determined as follows:

[21] (1) measuring a length of a two-dimensional contour of the curved surface reconstructed in step S1; and

[22] (2) obtaining the cladding passes based on a formula that the cladding passes=the length of the reconstructed two-dimensional contour of the curved surface/the movement distance of each of the passes.

[23] Optionally, by determining an initial point, the developed program automatically completes, according to the determined transverse displacement value and longitudinal displacement value between every two adjacent passes, multi-pass cladding processing.

[24] Optionally, when the movement distance of each of the passes is 2.94 mm, a statement name of moving from a first pass to a second pass is SLIN REL{Y 1.79, Z 2.31, C4}, C4 referring to that the cladding head rotates by 4°on the Y-Z plane while moving in the Y and Z directions every time of pass change.

[25] Optionally, a semiconductor and optical fiber coupled coaxial powder feeding laser cladding system is used to carry out cladding processing on the curved surface.

[26] Optionally, in step S3, the transverse displacement value and the longitudinal displacement value may be obtained through a measurement or marking function of the

AutoCAD software.

[27] Optionally, in step S4, movement, between adjacent passes, of the cladding head may be completed by running a KUKA program.

[28] Optionally, in step S5, whether the precision requirement is met may be determined when a starting point value and an ending point value of program running coincide with corresponding points of a part to be processed actually.

[29] The present invention has the advantages as follows:

[30] 1. The path development method for multi-pass linear cladding on a curved surface provided by the present invention may use the WorkVisual software configured in the KUKA robot to rapidly carry out manual programming without special additive manufacturing slicing and track planning software, to obtain a complex multi-pass linear cladding track program.

[31] 2. The path development method for multi-pass linear cladding on a curved surface provided by the present invention may be required to simply determine a starting point P1 for cladding, to automatically complete the multi-pass direct cladding processing on the complex curved surface.

[32] 3. The path development method for multi-pass linear cladding on a curved surface provided by the present invention may carry out upper and lower layer matching cladding in combination with the curved cladding on the curved surface, so that thermal stress and residual stress generated during cladding processing are effectively reduced, and a crack risk of an additively manufactured layer is reduced.

[33] 4. Compared to other cladding methods, such as selective laser melting (SLM), the path development method for multi-pass linear cladding on a curved surface provided by the present invention features a more flexible KUKA robot, a better cladding effect, simpler operation, lower technical requirements, and a wider application range.

BRIEF DESCRIPTION OF THE DRAWINGS

[34] FIG. 1 is a schematic diagram of a curved cladding track on a surface of a curved part;

[35] FIG. 2 is a schematic diagram of a linear cladding track on a surface of a curved part involved in a path development method for multi-pass linear cladding on a curved surface of the present invention;

[36] FIG. 3 is a contour diagram reconstructed through AutoCAD of a curved surface of a curved part in the path development method for multi-pass linear cladding on a curved surface of the present invention;

[37] FIG. 4 is an appearance diagram of a curved contour evenly divided through the AutoCAD of the curved surface in the path development method for multi-pass linear cladding on a curved surface of the present invention;

[38] FIG. 5 is a schematic diagram of measuring transverse displacement values and longitudinal displacement values between adjacent passes through a marking function of the AutoCAD in the path development method for multi-pass linear cladding on a curved surface of the present invention; and

[39] FIG. 6 is a surface appearance of a curved workpiece subjected to cladding processing using a program developed in the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[40] The specific implementation provided by the present invention is described in detail below in conjunction with the accompanying drawings.

[41] The reference numerals and components referred to in the accompanying drawings are as follows:

[42] Generally, it is obvious that the embodiments described in the present description are merely some feasible technical solutions of the present invention, and other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making inventive efforts should fall within the scope of protection of the present invention.

[43] The technical solutions between various embodiments of the present invention described in the present description may be combined with one another on the basis that they may be implemented by those of ordinary skill in the art. When leading to contradiction or failing in implementation, the combination between the technical solutions should be deemed non-existent.

[44] A path development method for multi-pass linear cladding on a curved surface of the present invention uses Work Visual software configured in a KUKA robot, to carry out program development. The method includes:

[49] with reference to FIGs. 1-6,

[46] S1: as shown in FIG. 2, in the present embodiment, a length and a width are each 50 mm, the curved surface has heights of a lowest point and a highest point of 137 mm and 150 mm, respectively, and a matrix material is low-carbon steel, which is primarily used as a certain type of mold insert in production. Since it is simply required to obtain a transverse displacement value and a longitudinal displacement value of each pass, with reference to FIG. 3, it is simply required to use AutoCAD software to reconstruct a two-dimensional contour of the curved surface.

[47] S2: in the present embodiment, a semiconductor and optical fiber coupled coaxial powder feeding laser cladding system is used to carry out cladding processing on the curved surface, where a single-pass cladding width of an apparatus is 4.2 mm, and a lapping rate between two adjacent passes is 30%, the lapping rate being a ratio of a lapping width between adjacent cladding passes to the single-pass cladding width during multi-pass cladding, that is, the apparatus may move by 4.2 mm*(1-30%)=2.94 mm in each of the passes. As shown in FIG. 4, a length of a contour curve of the curved surface reconstructed in S1 is measured as 58.58 mm. Therefore, the curve is required to be evenly divided into 20 parts, that is, 20-pass cladding is required.

[48] S3: as shown in FIG. 5, a measurement or marking function of the AutoCAD is used to measure transverse displacement and longitudinal displacement between adjacent passes.

[49] S4: according to displacement values measured in S3, a relative motion statement SLIN REL is used to compile a walking track of a cladding head in the

WorkVisual. As shown in FIG. 5, a statement name for moving from a first pass to a second pass is SLIN REL{Y 1.79,Z 2.31, C4}, C4 referring to that the cladding head rotates by 4° on a Y-Z plane while moving in Y and Z directions every time of pass change.

[50] In the above, 1.79?+2.312=2.94? that is, a movement distance? of each of the passes=Y?+Z.

[51] S5: a program compiled in S3 is subjected to trial running, and it is found that adistance difference, in the Y direction, between a final ending point of the program and an actual ending point of a workpiece is about 10%, while distances in the Z direction are almost the same. Therefore, a movement value Y in each of the passes in S4 is increased by 10% from an original value, and a value Z and a value C remain unchanged.

The program compiled in S3 runs again, and it is found that a final point of the program well coincides with an actual final point of the workpiece, that is, the program is developed. The program developed in the present embodiment is used to carry out cladding processing, and an appearance of a cladded workpiece is shown in FIG. 6. It can be seen that a cladding layer of each of the passes is uniformly and well formed, thereby meeting requirements of actual production.

[52] Therefore, the method of the present invention may rapidly realize program development of multi-pass linear cladding on the curved surface without special slicing and track planning software, and features a desirable cladding effect.

[53] Further, a method for reconstructing two-dimensional contour information of a curved surface in step S1 includes:

[54] according to size information on a part processing drawing or actually measured size values of the part, a two-dimensional contour drawing of the curved surface is drawn in the AutoCAD software.

[55] Further, a method for uniformly processing a curved surface in step S2 includes:

[56] according to a width of a single-pass cladding layer and the lapping rate between two adjacent passes, a total cladding pass n of the curved surface is determined.

A line segment equalization function in the AutoCAD is used, to evenly divide the contour curve of the curved surface reconstructed in S1 into n parts, where the line segment equalization function in the AutoCAD may be used to evenly divide the curved surface.

[57] Further, a method for measuring transverse displacement and longitudinal displacement between adjacent passes in step S3 includes:

[58] after the measurement or marking function of the AutoCAD software is used to evenly divide the curve, a transverse distance and a longitudinal distance between starting points of every two adjacent curve segments in a transverse direction and a longitudinal direction are determined.

[59] Further, a method for programming a cladding walking track in step S4 includes:

[60] According to a transverse movement displacement value Y and a longitudinal movement displacement value Z of each of cladding layers determined in S3 and an angle value by which the cladding head is required to deflect in each of the passes, displacement movement of the cladding head is programmed in the Work Visual software configured in KUKA, that is, the walking track is compiled through movement statements LIN, SLIN, LIN REL, SLIN REL, etc. of the KUKA robot. By changing position information (a transverse information value Y, a longitudinal information value

Z, and angle information value C) of the initial point P1, a required automatic cladding track program is compiled.

[61] Further, a method for feedback adjustment of a position movement value in step SS includes:

[62] As shown in FIG. 2, an angle of the cladding head is required to be rotated once after each cladding pass. Therefore, actuallly, tool coordinates of the KUKA robot are constantly changed during program running. Therefore, there is a certain error between movement position information obtained through the AutoCAD in S3 and a movement position actually required. Therefore, it is necessary to obtain an error range between walking precision of the program compiled in S4 and an actual position through trial running for adjustment.

[63] A specific adjustment method includes: an initial point P1 of cladding is set on a curved surface, and a walking track program compiled in S4 is subjected to trial running, and stopped at an ending point. A distance between the ending point of the program and an actual ending point of cladding the curved surface is measured, and then converted into an error ratio. According to the error ratio, the transverse displacement value and longitudinal displacement value between adjacent passes measured in S3 are increased or decreased in ratio (a rotary angle of the cladding head between two passes generally remains unchanged, and therefore no adjustment is required). Generally, as above, after adjustment one or two times, whether a starting point value and an ending point value of program running coincide with corresponding points of a part to be processed actually may be determined, to meet requirements of cladding processing.

[64] Further, compared to other cladding methods, such as selective laser melting (SLM), the present method features a more flexible KUKA robot, a better cladding effect, and simpler operation.

[65] FIG. 1 is a schematic diagram of a track of multi-pass curved cladding on a curved surface. Simple path planning is provided. It is simply required to determine a few more position points at different positions of the curve, and then these points are connected through polyline SPLINE(SPLINE denotes a spline curve), to generate the track as shown in the figure.

[66] FIG. 2 is a schematic diagram of a track of multi-pass linear cladding on a curved surface. A black arrow in the figure denotes a deflection angle of the cladding head in the cladding process. It can be seen that the cladding head is required to deflect by a certain angle between adjacent passes. Therefore, actually, a tool coordinate system of the robot is constantly changed, and it is relatively complex to plan such a path track.

[67] FIG. 3 is the two-dimensional contour diagram of the curved surface reconstructed in the present embodiment.

[68] As shown in FIG. 5, in the present embodiment, by designing left and right sides of the curve as symmetrical portions, only the transverse displacement and the longitudinal displacement between adjacent passes at one side are required to be measured.

[69] FIG. 6 shows a surface appearance of the curved workpiece subjected to cladding processing through the program developed in the present embodiment. It can be seen that the cladding layers at all parts of the curved surface are uniformly and well formed, thereby meeting production requirements.

[70] What is described above is merely the preferred implementation of the present invention. It should be noted that those of ordinary skill in the art may also make several improvements and supplements without departing from the method of the present invention, and these improvements and supplement should also fall within the scope of protection of the present invention.

Claims

Conclusions L Path development method for multi-pass linear coating on a curved surface, using AutoCAD to reconstruct contour information of a curved surface of a metal part, to obtain positional displacement information from a coating head and then configure it in a KUKA using Work Visual robot, for performing automatic program development, and includes the following: Sl: Obtaining dimensional information of the curved surface of the metal part to be machined and information to be reconstructed using the AutoCAD software of two-dimensional contour information of the curved surface of the reconstruct metal part; S2: then divide the curved surface evenly into corresponding parts in AutoCAD after determining cladding passes and a displacement distance of each of the passes, the parts being the same as the cladding passes; S3: measure and obtain transverse and longitudinal displacements between two adjacent passages using AutoCAD; S4: Using a relative displacement instruction SLIN REL to compile, in the Work Visual based on the transverse displacement and longitudinal displacement obtained between any two adjacent passes, a value for the position displacement of the coating head of each pass, where the name of the statement is SLIN REL{Y,Z,C}, where Y is a lateral displacement value, Z is a longitudinal displacement value, and C is a value of the cladding head angular information rotating on a Y-Z plane while moving in Y and Z directions every times of passage change moves, in the top, the displacement distance? of each of the passages Y?+Z? are; and S5: performing testing of a program, and adjusting, in proportion according to an error ratio value of a running result, a transverse displacement value and a longitudinal displacement value of each of the passes until a requirement of running accuracy is met.

The path development method for multi-pass linear coating on a curved surface according to claim 1, wherein in step S2 the displacement distance of each of the passes is calculated as follows: (1) determining a lap speed between two adjacent passes and a pass coating width of one device; and (2) multiplying the lapping width of the device in a single pass by (1-lap speed) to calculate the displacement distance of each of the passes.

The path development method for multi-pass linear coating on a curved surface according to claim 2, wherein in step S2 the coating passes are determined as follows: (1) measuring a length of a two-dimensional contour of the curved surface reconstructed in step S1; and (2) obtaining the coating passes based on a formula that the coating passes = the length of the reconstructed two-dimensional contour of the curved surface/the displacement distance of each of the passes.

The path development method for multi-pass linear coating on a curved surface according to claim 3, wherein by determining a starting point, the developed program automatically completes the multi-pass coating operation according to the determined lateral displacement value and the longitudinal displacement value between each two adjacent passes.

The path development method for multi-pass linear coating on a curved surface according to claim 4, wherein the instruction name of transitioning from a first pass to a second pass is SLIN REL{Y 1.79, Z 2.31, C4} when the travel distance of each of the passes is 2.94 mm, where C4 indicates that the coating head rotates 4° in the Y-Z plane while moving in the Y and Z directions with each pass change.

The path development method for multi-pass linear coating on a curved surface according to claims 1-5, wherein a semiconductor and optical fiber coupled coaxial powder feed laser coating system is used to perform coating processing on the curved surface.

The path development method for multi-pass linear coating on a curved surface according to claim 5, wherein in step S3, the transverse displacement value and the longitudinal displacement value may be obtained by a measurement or marking function of the AutoCAD software.

The path development method for multi-pass linear coating on a curved surface according to claim 7, wherein in step S4 the movement between adjacent passes of the coating head can be performed by executing a KUKA program.

The path development method for multi-pass linear coating on a curved surface according to claim 8, wherein in step SS, it can be determined whether the accuracy requirement is met when a start point value and an end point value of executing program coincide with corresponding points of a part to be machined.