A laser cutting and positioning method for irregularly shaped sheet metal parts

Abstract

This invention discloses a laser cutting positioning method for irregularly shaped sheet metal parts. The sheet metal part is clamped and positioned using a fixture. The fixture includes a base and a support frame formed by intersecting horizontal and vertical partitions on the base. The top contour of the support frame is adapted to the contour of the sheet metal part, and the sheet metal part covers the top of the support frame. The horizontal and vertical partitions are located in the low deformation and springback value area of ​​the sheet metal part. The base is equipped with clamping elements to fix the edges of the sheet metal part. Marking points are set on the base. The relative position information of the fixture and the sheet metal part is imported into laser cutting programming software. The program origin is determined according to the marking points, the angular direction of the fixture is aligned, the cutting boundary of the sheet metal part is extracted, and a laser cutting path is generated. This positioning method can minimize the avoidance of areas with large deformation of the sheet metal part, achieve stable and accurate positioning of the sheet metal part by the fixture, ensure good clamping consistency, and achieve precise cutting of subsequent boundaries.

Description

Technical Field

[0001] This invention relates to the field of laser cutting technology, and more specifically, to a laser cutting positioning method for irregularly shaped sheet metal parts. Background Technology

[0002] Laser cutting is a process that uses a focused laser to melt metal at high temperatures, and then uses a machine tool controlled by a program to create a cut. Due to its advantages such as high efficiency, high precision, small heat-affected zone, non-contact processing, and high flexibility, it is widely used in the processing of thin-walled sheet metal parts.

[0003] Aero engines contain numerous complex, irregularly shaped sheet metal parts, especially exhaust duct components which require control over airflow direction and exhaust efficiency, demanding high surface profile precision. The common process involves segmenting the duct components, cutting and assembling them, and then welding them into a complete assembly. Aero engine manufacturing demands stringent precision, requiring high boundary accuracy after sheet metal cutting. The complex boundary trajectories of irregularly shaped sheet metal parts, coupled with their curved surface characteristics, make positioning difficult. Issues such as springback during forming, thin sheet metal, and easy deformation further complicate tooling design. Because there has been no effective positioning fixture for these parts, and the parts lack obvious features for aligning the program origin and programming center, laser cutting cannot be used. Traditionally, manual trimming has been employed, but this method is inefficient, inaccurate, inconsistent, and results in highly unstable product quality.

[0004] Patent CN219703835U discloses a laser cutting support mold. The support mold includes a workpiece positioned above the mold, a frame, a base plate, a first support body, and support blocks. The base plate is fixed to the frame, and the bottom ends of the first support body are fixedly connected to both sides of the top surface of the base plate. The first support body includes a vertical plate and a support plate, with the support plate positioned on the front and rear sides of the vertical plate and vertically fixed to the vertical plate in a cross shape. The bottom ends of the vertical plate and the support plate are fixedly connected to the base plate, and the support blocks are fixed inside the support plate. The workpiece is positioned above the first support body, covering the top of the first support body. The front and rear sides of the vertical plate... Support blocks are arranged on both sides of the support plate, and the inner surface of the workpiece contacts the top of the support block. After the support blocks are installed, the support head is adjusted to adapt to the curved shape of the part. The support blocks form a multi-point support, and the position of the support head on the base is adjustable, which reduces the precision requirements of the support body and reduces the difficulty of mold manufacturing. The base is inclined on the support plate, and the tangent of the support head in contact with the part is the same as the tangent of the part at the top of the support plate. The support head and the support plate are spaced apart, and support points are evenly distributed on the inner surface of the part. The support head and the support plate work together to keep the part stable in the front and back position of the mold.

[0005] The support mold mentioned in the aforementioned patent is also designed for removing and positioning pre-reserved edges of parts with numerous irregular curved surfaces. However, its technical solution only focuses on the stable support of the parts and does not address the accuracy of the cut areas. Since the aforementioned irregularly shaped sheet metal parts are used in aero-engines, the cutting accuracy of the part boundaries directly affects the engine's exhaust performance. Therefore, there are currently no effective strategies for achieving precise positioning and stable clamping of laser-cut irregularly shaped sheet metal parts in the aero-engine field, and for ensuring boundary cutting accuracy. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a laser cutting positioning method for irregularly shaped sheet metal parts with thin plate thickness, many curved surfaces, and strict requirements for cutting boundary tolerances, in order to address the shortcomings of the existing technology.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for laser cutting and positioning irregularly shaped sheet metal parts, wherein the sheet metal parts are clamped and positioned using a fixture, the fixture including a base and a support frame formed by intersecting horizontal and vertical partitions on the base, the top contour of the support frame being adapted to the contour of the sheet metal parts, the sheet metal parts covering the top of the support frame, the horizontal and vertical partitions being positioned in the low deformation and springback value area of ​​the sheet metal parts; the base is provided with clamping elements to fix the edges of the sheet metal parts, and marking points are set on the base, the relative position information of the fixture and the sheet metal parts is imported into laser cutting programming software, the program origin is determined according to the marking points, the angular direction of the fixture is aligned, the cutting boundary of the sheet metal parts is extracted, and a laser cutting path is generated.

[0009] Furthermore, the deformation springback values ​​of each region of the sheet metal part are obtained through blue light scanning and contour difference analysis. Furthermore, 3 to 5 transverse and longitudinal partitions are each provided.

[0010] Furthermore, the transverse and longitudinal partitions are interlocked and connected to each other.

[0011] Furthermore, the transverse partition, longitudinal partition, and base are connected by an interlocking method, and the interlocking parts are welded and fixed.

[0012] Furthermore, the marked point is a positioning boss set on the base. The positioning boss cooperates with the center of the laser cutting machine tool turntable so that the placement of the fixture on the machine tool is consistent with the position information in the programming software. At this time, the center of the positioning boss coincides with the program origin.

[0013] Furthermore, the marked point is a hole machined on the base. The fixture is placed on the turntable of the laser cutting machine tool, so that the position of the fixture on the machine tool is consistent with the position information in the programming software. The position information of the machine tool turntable at this time is recorded and written into the program. The X-axis and Y-axis of the machine tool are moved to find the center of the hole and use it as the program origin for laser cutting.

[0014] Furthermore, the base has a hollow structure.

[0015] Furthermore, the clamping component includes a connecting rod and a guide rod vertically arranged on the base, and a pressure plate connected to the connecting rod via the connecting component. One end of the pressure plate overlaps the edge of the sheet metal part, and the end face of the guide rod and the pressure plate together clamp the edge of the sheet metal part.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The horizontal and vertical partitions of the support frame are selectively set in the low deformation and springback value area of ​​the sheet metal part, and at the same time, they are located in the position where the surface of the sheet metal part changes greatly. This can avoid the large deformation area of ​​the sheet metal part to the greatest extent, realize the stability and accurate positioning of the fixture on the sheet metal part, and have good clamping consistency, which provides a strong guarantee for the accurate cutting of the sheet metal part boundary in the future.

[0018] 2) By aligning the program origin with the marked points designed on the fixture, the laser cutting equipment controls the cutting trajectory through the program, which can significantly improve the consistency and efficiency of part processing and avoid the quality instability caused by the difference in skill level of traditional manual workers.

[0019] 3) The internal space of the fixture formed by the crisscrossing of the horizontal and vertical partitions facilitates airflow and allows the spatter generated during laser cutting to be blown out more easily and quickly, preventing it from adhering to the cutting surface of the sheet metal and improving the surface quality of the parts. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the fixture clamping sheet metal parts during laser cutting positioning as described in Example 1;

[0021] Figure 2 This is a schematic diagram of the sheet metal part profile change described in Example 1 (showing the longitudinal partition);

[0022] Figure 3 This is a schematic diagram of the springback of the sheet metal part described in Example 1;

[0023] Figure 4 This is a schematic diagram of the fixture described in Example 1;

[0024] Figure 5 for Figure 4 Top view of the fixture shown. Detailed Implementation

[0025] To clearly illustrate the technical features of this solution, the following detailed description, in conjunction with the accompanying drawings, will explain the technical solution in detail.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0027] Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0030] Example 1

[0031] This embodiment proposes a laser cutting positioning method applicable to irregularly shaped sheet metal parts with thinner sheet metal surfaces. More specifically, it targets flow channel sheet metal parts with many curved surfaces and strict cutting boundary tolerance requirements on aero engines, such as the right wall of the center tube of a certain type of aero engine. This method achieves precise clamping and positioning and program origin alignment during the laser cutting process of this sheet metal part, while ensuring consistent repeated clamping, making the laser cutting process of this type of sheet metal part feasible and maintaining the stability of cutting quality.

[0032] The aforementioned laser cutting positioning method specifically involves using a fixture to clamp and position the sheet metal part, such as... Figure 1 , Figure 4 and Figure 5 As shown, the fixture includes a base 1 and a support frame 2 formed by the crisscrossing of transverse partitions 21 and longitudinal partitions 22, which is mounted on the base. The top contour of the support frame 2 is adapted to the contour of the sheet metal part A, wherein the contour of the sheet metal part is as follows: Figure 2 The figure shows a curved section A1 and a straight section A2. Sheet metal part A covers the top of support frame 2 and maintains complete contact with the top contour of support frame.

[0033] The springback amount of sheet metal parts varies depending on the degree of deep drawing and stress deformation. For irregularly shaped sheet metal parts, the varying depth of drawing and material flow velocity in different areas lead to significant differences in springback amounts at different locations, resulting in discrepancies between the theoretical profile and the actual part contour, thus affecting the part's machining and positioning. To address this characteristic of irregularly shaped sheet metal parts, this invention places transverse and longitudinal partitions 21 in the low-deformation springback value areas of the sheet metal part: blue light scanning is performed on the sheet metal part to analyze contour differences and display the deformation springback value of each area. Figure 3 The diagram illustrates the springback of the sheet metal part in this embodiment. Horizontal partitions 21 and vertical partitions 22 are installed where the springback value is small, and these partitions are positioned as close as possible to the theoretical contour of the sheet metal part. For example… Figure 3In the middle, the transverse diaphragm 21 and the longitudinal diaphragm 22 are mainly set in the areas with deformation rebound values ​​of 0.01, 0.05, 0.1 and 0.3, avoiding the areas with deformation rebound values ​​above 0.4.

[0034] Since most of the curved surfaces on this sheet metal part are tangentially connected with a gentle slope, the clamping fixture is prone to sliding on the top contour of the support frame 2 after clamping, resulting in inconsistent clamping positions each time and affecting clamping consistency. Therefore, the transverse partitions 21 and longitudinal partitions 22 are preferably located in areas with obvious sheet metal part features and large surface changes, preferably in areas with more straight sections. Specifically, there should be a significant height difference between the tops of at least two adjacent transverse partitions 21 or two adjacent longitudinal partitions 22, for example, with Figure 2 Taking the curved surface segment indicated by label A1 as an example, a longitudinal partition 22 is set at each end of this curved surface segment, namely the starting end and the ending end, while the end of the transverse partition is designed to fit the straight section of the sheet metal edge, i.e. Figure 2 The end of the middle horizontal partition 21 is positioned in conjunction with the straight section A2 of the sheet metal part to achieve precise and stable positioning of the sheet metal part.

[0035] The number of horizontal and vertical partitions depends on the size of the sheet metal part. In this embodiment, three horizontal partitions 21 and four vertical partitions 22 are provided. The horizontal and vertical partitions 21 and 22 are interlocked, that is, slots are cut at the intersections of the horizontal and vertical partitions 21 and 22 to insert and fix them together, providing mutual support. The horizontal and vertical partitions 21 and 22 and the base 1 are also connected by interlocking, that is, the base 1 has slots at corresponding positions for the horizontal and vertical partitions 21 and 22 to insert, and are welded and fixed at the interlocking points. In addition, the base 1 is also designed as a hollow structure. The structural design of the fixture in this embodiment allows for a larger internal space, which is conducive to airflow. The spatter generated during laser cutting can also be blown out more easily and will not adhere to the vicinity of the cut surface, effectively improving the surface quality of the sheet metal part.

[0036] The base 1 is provided with a clamping component 3 to fix the edge of the sheet metal part. The clamping component 3 includes a connecting rod 31, a guide rod 32 and a support rod 33 vertically arranged on the base 1. It also includes a pressure plate 34 connected to the connecting rod through the connecting component 31. The first end of the pressure plate 34 overlaps the edge of the sheet metal part, and the second end abuts or connects with the end face of the support rod 33. The end face of the guide rod 32 contacts the edge of the sheet metal part. That is, the guide rod 32 and the pressure plate 34 jointly clamp the edge of the sheet metal part. The connecting rod 31 is preferably a threaded rod, and the connecting component is a nut that mates with the threaded rod. After the connecting rod passes through the pressure plate, it is screwed with the nut to achieve the clamping of the sheet metal part.

[0037] Marking points are set on base 1, specifically by setting a positioning boss 4 on the base (generally set at the center of the fixture). The positioning boss 4 is connected and cooperates with the center of the laser cutting machine tool turntable. The relative position information of the fixture and sheet metal parts is imported into the laser cutting programming software (generally, the UG models of the fixture and sheet metal parts are imported into the programming software). This ensures that the placement of the fixture on the machine tool is consistent with the position information in the programming software. A side is selected on the base to determine the angle of fixture placement. During processing, a dial indicator is used to confirm the correct placement of the parts and fixture. At this point, the program origin is determined, and the center of the positioning boss coincides with the program origin. After extracting the cutting boundary of the sheet metal parts, a laser cutting path is generated to simulate processing. After confirming that there are no errors, a laser cutting program is generated for processing.

[0038] The positioning method in this embodiment can avoid areas with large deformation of sheet metal parts to the greatest extent, achieve precise positioning, and make sheet metal parts replacement more convenient and quick. The fixture manufacturing cost is low, and its lightweight design makes it easier for workers to handle. It has good clamping consistency and realizes accurate cutting of the boundary of irregular sheet metal parts, ensuring the precision of parts and the consistency of processing. Processing efficiency and quality are also significantly improved. According to statistics, the processing efficiency has been reduced from several hours of traditional manual grinding to 2 to 5 minutes.

[0039] Example 2

[0040] The difference between this embodiment and embodiment 1 is as follows: the marked point is the hole machined on the base. The fixture is placed on the turntable of the laser cutting machine tool so that the position of the fixture on the machine tool is consistent with the position information in the programming software. The position information of the turntable of the machine tool is recorded at this time and written into the program. The X-axis and Y-axis of the machine tool are moved to find the center of the hole and use it as the program origin of laser cutting.

[0041] The specific steps for aligning the program origin are as follows: Place the fixture flat on the machine tool turntable, with the dial indicator at the side plane of the base. Move the Y-axis and record the readings of both dial indicators. Rotate the machine tool turntable until the readings of both dial indicators are consistent. At this point, the side of the fixture on the base is completely parallel to the Y-axis of the machine tool. Record the turntable values ​​at this time and input them into the program. Using a camera coaxial with the laser beam in the machine tool, move the X and Y axes of the machine tool to align the hole center, i.e., the program origin. Record the X and Y axis coordinate values ​​at this time and input them into the program. Fix the fixture. Through the above fixture alignment operation, the actual placement of the fixture is consistent with the program running settings. Clamp the sheet metal part on the fixture, ensuring that the sheet metal part is in place and then clamped by the clamping parts for laser cutting.

[0042] Example 3

[0043] The difference between this embodiment and Embodiment 1 is that the number of transverse and longitudinal partitions is different. In this embodiment, there are 4 transverse partitions and 5 longitudinal partitions.

[0044] Obviously, the above embodiments are merely examples to clearly illustrate the technical solutions of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A laser cutting and positioning method for irregularly shaped sheet metal parts, characterized in that, The sheet metal part is clamped and positioned using a fixture. The fixture includes a base and a support frame formed by intersecting horizontal and vertical partitions on the base. The top contour of the support frame is adapted to the contour of the sheet metal part, and the sheet metal part covers the top of the support frame. The horizontal and vertical partitions are located in the low deformation and springback value area of ​​the sheet metal part. The base is provided with clamping parts to fix the edge of the sheet metal part. Marking points are set on the base. The relative position information of the fixture and the sheet metal part is imported into the laser cutting programming software. The program origin is determined according to the marking points, the angular direction of the fixture is aligned, the cutting boundary of the sheet metal part is extracted, and the laser cutting path is generated. The deformation and springback values ​​of each area of ​​the sheet metal part are obtained through blue light scanning and contour difference analysis.

2. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The transverse diaphragm and longitudinal diaphragm are each provided in 3 to 5 pieces.

3. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The transverse and longitudinal partitions are interlocked and connected.

4. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The horizontal partition, vertical partition, and base are connected by an interlocking method.

5. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 4, characterized in that, The transverse and longitudinal partitions are welded and fixed at the insertion connection with the base.

6. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The marked point is a positioning boss set on the base. The positioning boss cooperates with the center of the laser cutting machine tool turntable so that the placement of the fixture on the machine tool is consistent with the position information in the programming software. At this time, the center of the positioning boss coincides with the program origin.

7. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The marked point is a hole machined on the base. The fixture is placed on the turntable of the laser cutting machine tool, and the position of the fixture on the machine tool is consistent with the position information in the programming software. The position information of the machine tool turntable at this time is recorded and written into the program. The X and Y axes of the machine tool are moved to find the center of the hole and use it as the program origin for laser cutting.

8. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The base has a hollow structure.

9. The laser cutting and positioning method for irregularly shaped sheet metal parts according to claim 1, characterized in that, The clamping component includes a connecting rod and a guide rod vertically arranged on the base, and a pressure plate connected to the connecting rod via the connecting component. One end of the pressure plate overlaps the edge of the sheet metal part, and the end face of the guide rod and the pressure plate together clamp the edge of the sheet metal part.

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