A processing method for a thin-wall part with special-shaped structure

Abstract

This invention discloses a processing method for irregularly shaped thin-walled parts, reducing welding difficulty and improving welding quality. The thin-walled part is a heat-insulating cover, comprising: using a welding block positioning fixture to mark lines, the welding block positioning fixture being positioned using reinforcing ribs and the heat-insulating cover profile on the large end face of the heat-insulating cover, the positioning fixture having an inner hole wall corresponding to the welding position of the welding block; after the welding block positioning fixture is placed upright and flat against the heat-insulating cover, it is positioned, and then a marking needle is used to mark lines along the inner hole wall of the positioning fixture; the heat-insulating cover is cut open along the marked lines to form an opening; the heat-insulating cover is placed on a flanging and rounding fixture, positioned using reinforcing ribs and the heat-insulating cover profile on the large end face of the heat-insulating cover, and a press is used to drive the flanging and rounding fixture to complete the pressing and flanging at the opening position; a flat and unfolded sheet metal for the welding block is selected and placed in a welding block forming mold, and pressed using a press; the processed welding block is overlapped with the heat-insulating cover and then welded.

Description

Technical Field

[0001] This invention relates to the field of sheet metal parts processing technology, and in particular to a processing method for irregularly shaped thin-walled parts. Background Technology

[0002] The turbocharger is one of the most important core components of a diesel engine. Among them, the heat shield, due to its complex structure and difficult welding, plays an important role in heat insulation, airflow guidance and protection as a cover for the bearing housing, and directly affects the overall performance and lifespan of the turbocharger.

[0003] The heat shield (hereinafter referred to as the heat shield) is composed of three parts: the heat shield body, the welding block, and the positioning ring, all of which are made of SUS321 austenitic stainless steel. Figure 1 As shown. The main heat insulation cover is trumpet-shaped, and the welded blocks have an irregular structure. As a part that covers the bearing housing, the irregular structure of the welded blocks is to avoid the bearing housing oil return pipe structure. The part as a whole is relatively large (see dimensions). Figure 2 The large end has a diameter of Φ612, the small end has a diameter of Φ210, and the height is 232. Welding is difficult, and the thin-walled part makes it difficult to process the welding block position and results in poor welding quality.

[0004] When the welding block is welded to the main body of the heat insulation cover, because its mating surface is an irregular curved surface, such as... Figure 3 As shown, manual sheet metal processing methods make it difficult to guarantee a good fit. When welding with the heat insulation cover, a large gap is easily formed, resulting in difficult welding, unsightly welds, and poor welding quality.

[0005] If manual sheet metal bending is used for welding, the process is difficult, requires high operator skills, results in poor appearance, and produces sharp edges, making welding difficult, resulting in poor welding quality and localized stress concentration in the parts.

[0006] If a special tooling is used to directly press the heat insulation cover of the main part into a protruding whole (without welded block structure), the wall of the protruding part will be thin after molding due to its large size. The thickness uniformity of the part will be poor, the strength will be low, and it will not meet the design and working conditions. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a processing method for irregular structures of thin-walled parts, thereby reducing welding difficulty and improving welding quality.

[0008] The objective of this invention is achieved as follows:

[0009] A method for processing a thin-walled part with an irregular shape, wherein the thin-walled part is a flow-guiding heat insulation cover, the flow-guiding heat insulation cover having a heat insulation cover body, includes the following steps:

[0010] S1, line drawing

[0011] After the heat insulation cover is processed, the welding block positioning fixture is used to mark the lines. The welding block positioning fixture is positioned by the reinforcing ribs on the large end face of the heat insulation cover and the heat insulation cover profile. The positioning fixture has an inner hole wall corresponding to the welding position of the welding block. After the welding block positioning fixture is placed upright and flat against the heat insulation cover, the positioning fixture is positioned, and then the line is marked along the inner hole wall of the positioning fixture with a scribing needle.

[0012] S2, Opening

[0013] Use an angle grinder or laser cutter to cut open the heat insulation cover along the marked lines to form an opening. The opening should be smooth, without any sharp edges or corners.

[0014] S3, Flanging and Rounding

[0015] Place the heat insulation cover on the flange rounding fixture, use the reinforcing ribs on the large end face of the heat insulation cover and the heat insulation cover profile to position it, use the press to drive the flange rounding fixture, and complete the pressing and flange of the opening position so that the opening position is adapted to the angle required for welding.

[0016] S4, Welding block processing

[0017] Select flat, unfolded sheet material for welding blocks, place it in a welding block forming mold, and press it with a press for 5-10 seconds to form it.

[0018] S5, Welding

[0019] After the processed welding blocks are overlapped with the heat insulation cover, they are spot welded to fix them. After checking that there are no errors, the overlapped positions are then welded.

[0020] Preferably, the inner surface of the welding block positioning fixture is used to mate with the heat insulation cover body shape line for positioning, and the bottom two ends of the welding block positioning fixture are respectively provided with positioning legs, which are used to mate with the reinforcing ribs on the large end face of the heat insulation cover body for positioning.

[0021] Preferably, handles are installed on both sides of the welding block positioning fixture.

[0022] Preferably, the inner side of the positioning leg of the welding block positioning fixture is provided with an inclined surface, which is used to be positioned obliquely against the outer side of the corresponding reinforcing rib.

[0023] Preferably, the flange rounding fixture includes an upper mold and a lower mold. The surface of the lower mold is used to cooperate and position with the heat insulation cover body profile. The lower mold is also provided with a positioning structure and a flattening structure. The positioning structure is used to cooperate and position with the reinforcing ribs on the large end face of the heat insulation cover body. The flattening structure is used to flatten the large end face of the heat insulation cover body. The upper mold has a limiting module and a forming module. The limiting module slides and fits on the forming module. The limiting module is connected to the upper mold through a spring mechanism. The limiting module is used to press the heat insulation cover body. The forming module is used to form and flange the edge of the opening.

[0024] Preferably, the welding block forming mold includes an upper die punch, a fixed plate, an upper die base, and a lower die base. The fixed plate is installed on the lower die base, the upper die punch is installed on the upper die base, and the fixed plate is provided with a forming groove corresponding to the upper die punch.

[0025] Preferably, the welding block is made of stainless steel, has springback deformation, and the included angle after forming is required to be 84°, while its forming included angle is 70°.

[0026] Preferably, the heat shield is a heat shield for the axial flow turbocharger of the CTA series low-speed diesel engine.

[0027] By employing the above-mentioned technical solutions, this invention, through the design of welding block positioning fixtures, welding block forming fixtures, and specialized heat insulation cover flange rounding fixtures, and through reasonable processing methods, ensures that the flanged portion of the part at the welding position is tightly fitted to the inner and outer surfaces of the curved surface of the welding block, reducing the fitting gap and thus reducing repeated welding, thereby reducing welding difficulty and improving welding quality. Furthermore, it achieves a smooth transition at the welding position of the welding block, improving the strength performance near the welding block of the heat insulation cover, and avoiding irregular and uneven weld area connections caused by manual flange bending, which can lead to stress concentration and reduced welding strength in localized areas of the part. This invention has the following beneficial effects:

[0028] ① By using a special welding block forming tool, and through continuous verification, the angle and profile data of the forming tool were finally confirmed, reducing manual operation errors, ensuring the fit dimensions between the subsequent welding block and the heat insulation cover, reducing welding difficulty, and improving product quality.

[0029] ② A smooth transition at the welding position of the welding block is achieved, which improves the strength performance near the welding block of the heat shield and avoids the irregular connection and lack of smooth transition of the welding area caused by manual folding, which leads to stress concentration and thus reduces the welding strength of the local area of ​​the part. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the heat shield structure.

[0031] Figure 2 Here is a drawing showing the dimensions of the heat insulation enclosure;

[0032] Figure 3 This is a schematic diagram showing the fit between the welded block and the main body.

[0033] Figure 4 Schematic diagram of the positioning fixture for the welding block;

[0034] Figure 5 A three-view diagram of the positioning fixture for the welding block;

[0035] Figure 6 Schematic diagram of how to use the positioning fixture for welding blocks;

[0036] Figure 7 This is a schematic diagram of the welding block forming mold structure;

[0037] Figure 8 This is a schematic diagram of the lower die section of the flange rounding tooling;

[0038] Figure 9 This is a schematic diagram of the upper die part of the flange rounding tooling;

[0039] Figure 10 This is a schematic diagram illustrating the fit between the welded block and the heat insulation cover.

[0040] Figure 11 This is a schematic diagram of the rounded corner transition in the welding block area. Detailed Implementation

[0041] Tooling required for a machining method of irregularly shaped thin-walled parts:

[0042] (1) Welding block positioning fixture

[0043] This tooling uses the reinforcing ribs on the large end face of the heat insulation cover and the heat insulation cover profile for positioning and fixing. The purpose is to accurately position the welding block on the main body of the heat insulation cover, laying the foundation for the subsequent flanging and rounding position.

[0044] (2) Welding block forming mold

[0045] The welded block has an irregular shape, making it difficult to manually round and straighten it using sheet metal, resulting in inconsistent processing quality and difficulty in meeting design requirements. Therefore, a welding block forming mold was designed. This tooling consists of a positioning plate, a fixing plate, an upper mold, and a lower mold. It has a simple structure and is easy to disassemble. The positioning plate limits the welding block's forming dimensions. Considering its structure and the springback deformation of the stainless steel material, the drawing requires an included angle of 84° after forming. After repeated verification, it was found that the welding block could only meet the design requirements after stamping when the included angle of the concave die surface of the stamping tooling was 70°.

[0046] (3) Fixture for flanging and rounding the heat insulation cover

[0047] Positioning and leveling are achieved by using the reinforcing ribs and outer contour curves of the heat insulation cover itself, so that the heat insulation cover is fixed on the lower mold of the tooling. During the pressing process, the limiting module of the upper mold first presses the heat insulation cover through the spring mechanism to prevent the part from shifting during pressing, and then controls the upper mold to press slowly.

[0048] A method for machining irregularly shaped thin-walled parts:

[0049] ① Marking: After the main body of the heat insulation cover is processed, mark the lines using the welding block positioning fixture. The fixture is positioned using the reinforcing ribs and the heat insulation cover shape lines on the large end face of the heat insulation cover. After placing the fixture upright and flat against the heat insulation cover, fix it in place. Use a scriber to draw a solid line evenly along the inner wall of the positioning fixture.

[0050] ② Opening: Use an angle grinder or laser cutter to cut open the heat insulation cover along the marked line, ensuring that the opening is smooth and without sharp edges or corners.

[0051] ③ Flanging and Rounding: Place the heat insulation cover on the flanging and rounding fixture, use the reinforcing ribs on the large end face of the heat insulation cover and the heat insulation cover profile to position and fix it, use a hydraulic press to press and form the flanging with the upper mold of the fixture. During the pressing process, the upper mold fixing part of the fixture contacts the heat insulation cover first to fix it, so that the movement of the part is guaranteed during the pressing process.

[0052] ④ Welding block processing: Select flat and unfolded welding block sheet material and place it in the welding block forming mold. Use a hydraulic press to press and fix it for 5-10 seconds to make it completely formed.

[0053] ⑤ Welding: Spot weld the processed welding block to the heat insulation cover body with an overlap of 10mm. This is to ensure that the welding position coincides when fully welding, thereby improving the welding quality. After observing and confirming that there are no errors, weld the overlap position of the inner and outer rings.

[0054] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for processing a thin-walled part with an irregular shape, wherein the thin-walled part is a flow-guiding heat insulation cover, the flow-guiding heat insulation cover having a heat insulation cover body, characterized in that, Includes the following steps: S1, line drawing After the heat insulation cover is processed, the welding block positioning fixture is used to mark the lines. The welding block positioning fixture is positioned using the reinforcing ribs on the large end face of the heat insulation cover and the heat insulation cover profile. The welding block positioning fixture has an inner hole wall corresponding to the welding position of the welding block. After the welding block positioning fixture is placed upright and flat against the heat insulation cover, it is positioned, and then the line is marked along the inner hole wall of the welding block positioning fixture with a scribing needle. S2, Opening Use an angle grinder or laser cutter to cut open the heat insulation cover along the marked lines to form an opening. The opening should be smooth, without any sharp edges or corners. S3, Flanging and Rounding Place the heat insulation cover on the flange rounding fixture, use the reinforcing ribs on the large end face of the heat insulation cover and the heat insulation cover profile to position it, use the press to drive the flange rounding fixture, and complete the pressing and flange of the opening position so that the opening position is adapted to the angle required for welding. S4, Welding block processing Select flat, unfolded sheet material for welding blocks, place it in a welding block forming mold, and press it with a press for 5-10 seconds to form it. S5, Welding After the processed welding blocks are overlapped with the heat insulation cover, they are spot welded to fix them. After checking that there are no errors, the overlapped positions are then welded.

2. The processing method for a thin-walled part with an irregular shape according to claim 1, characterized in that: The inner surface of the welding block positioning fixture is used to match and position with the heat insulation cover body shape line. The bottom two ends of the welding block positioning fixture are respectively provided with positioning legs, which are used to match and position with the reinforcing ribs on the large end face of the heat insulation cover body.

3. The method for processing irregularly shaped thin-walled parts according to claim 1, characterized in that: Handles are installed on both sides of the welding block positioning fixture.

4. The method for processing irregularly shaped thin-walled parts according to claim 2, characterized in that: The positioning legs of the welding block positioning fixture have an inclined surface on the inside, which is used to be positioned obliquely against the outer side of the corresponding reinforcing rib.

5. The method for processing irregularly shaped thin-walled parts according to claim 1, characterized in that: The flange rounding fixture includes an upper mold and a lower mold. The surface of the lower mold is used to match and position with the shape line of the heat insulation cover. The lower mold is also equipped with a positioning structure and a flattening structure. The positioning structure is used to match and position with the reinforcing ribs on the large end face of the heat insulation cover. The flattening structure is used to flatten the large end face of the heat insulation cover. The upper mold has a limit module and a forming module. The limit module slides and fits on the forming module. The limit module is connected to the upper mold through a spring mechanism. The limit module is used to press the heat insulation cover. The forming module is used to form and flange the edge of the opening.

6. The method for processing irregularly shaped thin-walled parts according to claim 1, characterized in that: The welding block forming mold includes an upper die punch, a fixed plate, an upper die base, and a lower die base. The fixed plate is installed on the lower die base, and the upper die punch is installed on the upper die base. The fixed plate has a forming groove corresponding to the upper die punch.

7. The method for processing irregularly shaped thin-walled parts according to claim 1, characterized in that: The welding block is made of stainless steel and has springback deformation. After forming, the included angle is required to be 84°, and its forming included angle is 70°.

8. The method for processing irregularly shaped thin-walled parts according to claim 1, characterized in that: The flow guide heat shield is a flow guide heat shield for the axial flow turbocharger of the CTA series low-speed diesel engine.

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