A forming method for cylindrical frame-shaped parts

Abstract

The present invention discloses a method for forming a cylindrical frame-shaped part. First, a circular sheet is punched out from sheet metal, which is then stretched into a long cylinder with a closed bottom and an outward-turned upper end. The sheet is then cut, flanging, and flaring to form a long cylinder with equal diameter and expanded holes at both ends. The wall of the long cylinder is then punched out twice to form four equally spaced sidewalls. Two symmetrical sidewalls are then punched out from two directions, 180 degrees apart. Finally, the long cylinder is shaped using a waist-constricting and height-squatting process, concave the remaining two symmetrical sidewalls inward to the desired radial dimension, and the height of the long cylinder is reduced to the desired height. The entire manufacturing process utilizes punching and stamping techniques, which is more cost-effective than traditional casting and CNC machine tool processing.

Description

Technical Field

[0001] The invention belongs to the technical field of metal processing and forming, and in particular relates to a forming method of a cylindrical frame-shaped part. Background Art

[0002] like Figure 13 The cylindrical frame-shaped part shown here is a plastic frame component used in automotive shock absorbers. Made of JSH270C with a thickness of 2.0mm, this product presents a challenge in maintaining an average diameter tolerance of ±0.2mm for the inner and outer diameters. This requires glue injection during subsequent manufacturing, and any dimensional inaccuracies can lead to glue leakage. Current technologies rely on casting and CNC machine tool cutting, which are prohibitively expensive. This invention innovatively designs a method for forming cylindrical frame-shaped parts using blanking and stamping processes. Summary of the Invention

[0003] The purpose of the present invention is to solve the technical problem of high cost of existing processing methods and to provide a new forming method for cylindrical frame-shaped parts.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for forming a cylindrical frame-shaped part comprises the following steps:

[0006] Step 1: Punch out a circular sheet from the sheet;

[0007] Step 2: Using a stretching die, the circular sheet is stretched into a long cylinder with a closed bottom and an open top;

[0008] Step 3: Continue stretching the long cylinder obtained in step 2 to reduce its diameter and increase its height. The height should be greater than the height of the target product to be formed, leaving a margin.

[0009] Step 4: stamping and shaping the long cylinder obtained after stretching in step 3 to reduce the R angle of the outward-turned opening at the upper end of the long cylinder and form a flat flange around the R angle, with the flange perpendicular to the cylinder body;

[0010] Step 5: Cut off the excess portion of the flange, and the cut surface on the flange is perpendicular to the flange plane;

[0011] Step 6: Flanging the remaining flanges and R corners on the long cylinder to make it a completely long cylinder with equal diameter;

[0012] Step 7: Punch out the bottom side of the long cylinder to obtain a long cylinder with equal diameter and open at both ends;

[0013] Step 8, expanding the two ends of the long cylinder obtained in step 7;

[0014] Step 9, punching the wall of the expanded long cylinder obtained in step 8 to form four equally spaced punching areas on the wall of the long cylinder;

[0015] Step 10: Rotate the long cylinder at a certain angle and continue punching the wall of the long cylinder from four directions. The punching areas in this step are offset by a certain distance along the circumference of the long cylinder compared to the four punching areas in step 9, and overlap is ensured. After punching in step 10, the four punching areas on the wall of the long cylinder are further expanded compared to step 9. After punching in step 10, four side walls are formed on the wall of the long cylinder with equal spacing along the circumference.

[0016] Step 11: symmetrically punch out the wall of the long cylinder obtained in step 10 from two directions at 180 degrees apart, punching out two symmetrical side walls;

[0017] Step 12, finally, the waist-tightening and squatting process is used to shape the long cylinder obtained in step 11, so that the remaining two symmetrical side walls on the wall of the long cylinder are concave inward to the radial size required by the product, and the height of the long cylinder is reduced to the height required by the product.

[0018] In the above technical solution, in step 6, after the flange and the R angle are flanging, the top section of the flange is perpendicular to the barrel.

[0019] In the above technical solution, in step 9, the wall of the expanded long cylinder obtained in step 8 is punched out from four directions at 90 degrees along the circumference of the long cylinder; the punching is performed symmetrically to prevent radial deformation of the wall of the long cylinder.

[0020] The advantages and beneficial effects of the present invention are:

[0021] The forming method of the cylindrical frame-shaped parts of the present invention entirely adopts blanking and stamping processing techniques, which is lower in cost than traditional casting and CNC machine tool processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the circular flake obtained in step 1 of the present invention.

[0023] Figure 2 Schematic diagram of the long cylinder obtained in step 2 of the present invention.

[0024] Figure 3 Schematic diagram of the long cylinder obtained in step 3 of the present invention.

[0025] Figure 4 This is a schematic diagram of the long cylinder with flange obtained in step 4 of the present invention.

[0026] Figure 5 This is a schematic diagram of the long cylinder after cutting the flange obtained in step 5 of the present invention.

[0027] Figure 6 Schematic diagram of the long cylinder obtained in step 6 of the present invention.

[0028] Figure 7 Schematic diagram of the long cylinder obtained in step 7 of the present invention.

[0029] Figure 8 Schematic diagram of the long cylinder obtained in step 8 of the present invention.

[0030] Figure 9 Schematic diagram of the long cylinder obtained in step 9 of the present invention.

[0031] Figure 10 This is a schematic diagram of the blanking process in step 10 of the present invention.

[0032] Figure 11 Schematic diagram of the long cylinder obtained in step 10 of the present invention.

[0033] Figure 12 Schematic diagram of the long cylinder obtained in step 11 of the present invention.

[0034] Figure 13 Schematic diagram of the long cylinder obtained in step 12 of the present invention.

[0035] Figure 14 This is a schematic diagram of the initial state of the waist-tightening and squatting machine tool according to the second embodiment of the present invention.

[0036] Figure 15 This is a partial schematic diagram of a waist-retracting and squatting machine tool with a top cylinder according to the second embodiment of the present invention.

[0037] Figure 16 This is a schematic diagram of the workpiece pressing and positioning state of the waist-lowering and squatting machine tool according to the second embodiment of the present invention.

[0038] Figure 17 This is a schematic diagram of the waist-tucked state of the waist-tucked squat machine tool according to the second embodiment of the present invention.

[0039] Figure 18 This is a schematic diagram of the squatting state of the waist-tightening squatting machine tool according to the second embodiment of the present invention.

[0040] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention are further described below with reference to specific embodiments.

[0042] Example 1

[0043] A method for forming a cylindrical frame-shaped part comprises the following steps:

[0044] Step 1: Use a circular punch to punch out a circular sheet from the sheet, such as Figure 1 shown.

[0045] Step 2: Use a stretching die to stretch the circular sheet into a long cylinder with a closed bottom and an open top. Figure 2 shown.

[0046] Step 3, see attached Figure 3 , continue to stretch the long cylinder obtained in step 2, reduce its diameter and increase its height. The height should be greater than the height of the target product to be formed, leaving a margin, such as Figure 3 shown.

[0047] Step 4: Punch and shape the long cylinder obtained after stretching in step 3, slightly reduce its diameter to meet the design requirements, and at the same time reduce the R angle of the outward-turned opening at the upper end of the long cylinder, and form a circle of flat flange 101 around the R angle. The flange 101 is perpendicular to the barrel of the long cylinder, as shown in FIG. Figure 4 shown.

[0048] Step 5: According to the length of the material, use a circular punch to cut off the excess flange on the flange. The cut surface on the flange is perpendicular to the flange plane, such as Figure 5 shown.

[0049] Step 6: Flanging the remaining flange and R angle on the long cylinder to make it a completely long cylinder with equal diameter, such as Figure 6 As shown. Since the section on the flange in step 5 is perpendicular to the flange plane, and the flange is perpendicular to the cylinder body in step 4, after the flange and R angle are flanging, the top section of the flange is perpendicular to the cylinder body, which ensures that the top surface of the long cylinder of equal diameter formed after flanging is flat.

[0050] Step 7: Punch out the bottom side of the long cylinder to obtain a long cylinder with equal diameter and open at both ends, such as Figure 7 shown.

[0051] Step 8, through the expansion process, the two ends of the long cylinder obtained in step 7 are expanded, such as Figure 8 shown.

[0052] Step 9: Punch the wall of the expanded long cylinder obtained in step 8 from four directions at 90 degrees along the circumference of the long cylinder, thereby forming four equally spaced punching areas 102 on the wall of the long cylinder; the punching must be performed symmetrically to prevent radial deformation of the wall of the long cylinder and ensure the strength of the long cylinder. Figure 9 shown.

[0053] Step 10, see attached Figure 10 , rotate the long cylinder at a certain angle, and continue to punch out the cylinder wall of the long cylinder from four directions. The punching area in this step is offset by a certain distance along the circumference of the long cylinder compared to the four punching areas in step 9, but overlap is ensured. Therefore, after the punching in step 10, the four punching areas on the cylinder wall of the long cylinder are further expanded compared to step 9; and then, four side walls 103 distributed at equal intervals along the circumference are formed on the cylinder wall of the long cylinder after punching in step 10, see the attached Figure 11 .

[0054] Step 11, symmetrically punch out the wall of the long cylinder obtained in step 10 from two directions at 180 degrees apart, and punch out two symmetrical side walls 103, as shown in FIG. Figure 12 shown.

[0055] Step 12, finally, the waist-reducing and squatting process is used to reshape the long cylinder obtained in step 11, so that the remaining two symmetrical side walls on the long cylinder wall are concave inward to the radial size required by the product, and the height of the long cylinder is reduced to the height required by the product, and finally the required product is obtained, such as Figure 13 shown.

[0056] Example 2

[0057] The waist-tightening and squat-heightening processing in step 12 above can be completed by first performing waist-tightening shaping and then squat-height shaping, which requires two steps to complete.

[0058] This embodiment introduces a waist-retracting and squatting machine tool that can complete the waist-retracting and squatting processing in step 12 at one time. The machine tool can complete the clamping and positioning, waist-retracting, squatting and unloading processes of the workpiece in sequence during one mold closing and opening process, greatly improving efficiency.

[0059] See attached Figure 14 and attached Figure 15 The waist-lowering and squatting machine tool includes an upper mold part and a lower mold part.

[0060] The upper die part includes an upper die base 1 and a limit top plate 2, a movable top plate 3, an upper mold insert 4, an inclined wedge 5 and an upper ejector rod 19 (the upper ejector rod 19 is shown in the attached figure). Figure 15), wherein the limiting top plate 2 is fixedly installed in the groove on the bottom surface of the upper die base 1, the movable top plate 3 is located below the limiting top plate 2, and the movable top plate 3 is installed on the upper die base 1 through a first spring mechanism 31. When the movable top plate 3 is subjected to an upward force, the movable top plate 3 can move toward the limiting top plate 2 above it; the upper mold insert 4 is vertically slidably embedded in the movable top plate 3, and the upper mold insert 4 is connected to the upper die base 1 above it through a second spring mechanism 32. The upper mold insert 4 is used to act on the inner wall of the top of the workpiece to be formed. The outer periphery of the upper mold insert 4 has a 45-degree inclined surface, which can position the top inner wall of the workpiece to be formed; the inclined wedge 5 is fixedly installed on the bottom of the upper die base 1 by bolts; the upper ejector rod 19 is vertically fixed downward on the upper die base 1.

[0061] A first limiting bolt 41 is connected between the movable top plate 3 and the limiting top plate 2, which is used to limit the movable top plate 3 to the extreme position where it is pushed downward by the first spring mechanism 31; a second limiting bolt 42 is connected between the upper mold insert 4 and the limiting top plate 2, which is used to limit the upper mold insert 4 to the extreme position where it is pushed downward by the second spring mechanism 32.

[0062] Furthermore, preferably, a vertical guide rod 50 is provided between the upper mold insert 4 and the limiting top plate 2 to ensure that the upper mold insert 4 can move vertically and stably along the guide rod.

[0063] The lower mold part includes a lower mold base 6, a movable template 7, a radial waist-retracting mechanism 8 driven by the inclined wedge 5, a forming inner core 9, a lower mold base 10, a positioning support column 11, a spring 12, a limit plate 13, a first elastic support mechanism 15, a second elastic support mechanism 16, a first lower push rod 18.1 and a second lower push rod 18.2.

[0064] The movable template 7 is installed above the lower die base 6 through the first elastic support mechanism 15. Under the action of the first elastic support mechanism 15, there is a certain gap between the movable template 7 and the lower die base 6 in the natural state. This gap prepares for the last step of squatting the parts (which will be described in detail later); a mounting hole is provided at the center of the movable template 7, and the lower die base 10 is installed through the mounting hole. A groove 10.1 is provided on the upper part of the lower die base 10, and the molding core 9 is movably installed in the groove 10.1 of the lower die base 10, and a spring 12 is provided between the lower die base 10 and the molding core 9, and the spring 12 provides a force for the lower die base 10 and the molding core 9 to move away from each other; the molding core The diameter of the upper part of 9 is smaller than the diameter of the lower part. When the workpiece to be formed is inserted into the forming inner core 9, the lower part of the forming inner core 9 can play a positioning role on the inner wall of the lower part of the workpiece, and the small diameter of the upper part of the forming inner core 9 is to enable the workpiece to be waisted and formed; the bottom of the lower mold base 10 has an enlarged stepped base 10.2, and the diameter of the stepped base 10.2 is larger than the mounting hole diameter of the movable template 7, so that the stepped base 10.2 limits the upward limit position of the lower mold base 10; the positioning support column 11 is vertically arranged, and its top end is fixedly connected to the forming inner core 9, and its bottom end is provided with an enlarged circular table 11.1, and the enlarged circular table 11.1 at the bottom end of the positioning support column 11 is movably mounted on the lower mold base 6 In a limiting groove 17, the depth of the limiting groove 17 is greater than the height of the expansion cone 11.1, and the limiting plate 13 is fixedly installed on the limiting groove 17, and the positioning support column 11 passes through the limiting plate 13. Under the limiting action of the limiting plate 13 on the expansion cone 11.1, the upward limit position of the positioning support column 11 can be limited, that is, the upward limit position of the forming inner core 9 is limited (because the forming inner core 9 is fixedly connected to the top of the positioning support column 11). In this way, even if the spring 12 provides a force for the lower mold base 10 and the forming inner core 9 to move away from each other, the forming inner core 9 will not fall out upward; the second elastic support mechanism 16 is arranged in the lower mold base 6 and is located at the positioning support column 11 The lower part plays an upward elastic supporting role for the positioning support column 11; the radial waist-shrinking mechanism 8 is arranged on the movable template 7, and the radial waist-shrinking mechanism 8 can be driven by the inclined wedge 5 to apply radial jacking force to the outer wall of the hollow cylindrical workpiece to shrink the workpiece; the first lower ejector rod 18.1 is vertically movably installed in the lower die base 6, and the top end of the first lower ejector rod 18.1 is located at the bottom of the stepped base 10.2 of the lower mold base 10 (the top end of the first lower ejector rod 18.1 has no connection with the bottom of the stepped base 10.2, but is only located at the bottom of the stepped base 10.2), and the bottom end of the first lower ejector rod 18.1 is connected to the top cylinder of the machine tool; the second lower ejector rod 18.2 is also vertically movably installed in the lower die base 6 (see Figure 15), the bottom end of the second lower ejector rod 18.2 is also connected to the top cylinder of the machine tool, and the top end of the second lower ejector rod 18.2 is connected to an intermediate rod 20; the second lower ejector rod 18.2 and the upper ejector rod 19 on the upper die base 1 are located on the same straight line. When the upper die base 1 moves downward, the upper ejector rod 19 will press down the middle rod 20 and the second lower ejector rod 18.2, compressing the top cylinder of the compression machine tool. Since the top cylinder is also connected to the first lower ejector rod 18.1, when the top cylinder of the machine tool is compressed, the top cylinder of the machine tool will synchronously drive the first lower ejector rod 18.1 to descend. After the first lower ejector rod 18.1 descends, the lower mold base 10 loses the supporting effect of the first lower ejector rod 18.1, and under the action of the spring 12, the spring 12 will press the lower mold base 10 downward, so that the lower mold base 10 reaches the limit position of the limit plate 13 (that is, the limit plate 13 is the downward limit position of the lower mold base 10). At this time, the upper mold insert 4 and the lower mold base 10 press the workpiece to be formed up and down to stably position the workpiece; when the upper die base 1 returns upward, the top cylinder of the machine tool extends, so that the first lower ejector rod 18.1 drives the lower mold base 10 to move upward, thereby ejecting and unloading the workpiece after forming.

[0065] Furthermore, the radial waist-shrinking mechanism 8 includes a mounting frame and a wedge-shaped block 8.1, a waist-shrinking punch 8.2 and a return spring 8.3 arranged on the mounting frame, wherein the waist-shrinking punch 8.2 is connected to the wedge-shaped block 8.1. When the upper die base 1 drives the inclined wedge 5 to move downward to above the wedge-shaped block 8.1 of the radial waist-shrinking mechanism 8 and contacts it, as the upper die base 1 continues to move downward, the inclined wedge 5 will trigger the wedge-shaped block 8.1 to move horizontally with the waist-shrinking punch 8.2 toward the forming inner core 9, thereby shrinking the workpiece mounted on the forming inner core 9; the return spring 8.3 is connected to the wedge-shaped block 8.1 to provide a horizontal outward restoring force for the wedge-shaped block 8.1, so that after the workpiece is processed, the waist-shrinking punch 8.2 and the wedge-shaped block 8.1 can be reset after the upper die base 1 returns.

[0066] Furthermore, the spring 12 is sleeved on the positioning support column 11 , and a mounting cavity for placing the spring 12 is provided on the lower mold base 10 .

[0067] Furthermore, a first limiting column 22 is provided on the movable template 7, which is used to limit the minimum limit distance between the movable template 7 and the upper die base 1, so as to achieve two functions: one is to limit the limit trigger position of the inclined wedge 5 on the radial waisting mechanism 8; the second is that when the upper die base 1 contacts the first limiting column 22, as the upper die base 1 continues to move downward, the upper die base 1 will drive the movable template 7 downward (in this process, the distance between the movable template 7 and the upper die base 1 remains unchanged) to complete the squatting height of the workpiece.

[0068] Furthermore, a second limiting column 21 (see attached) is provided on the lower die base 6. Figure 15), which is used to limit the downward movement position of the upper die base 1, and at the same time, also limits the downward movement position of the movable template 7 (because the movable template is driven downward by the upper die base 1).

[0069] Furthermore, the number of the inclined wedges and radial waist-tightening mechanisms 8 is determined according to actual processing needs, and the drawings of this embodiment only show one set of inclined wedges and radial waist-tightening mechanisms 8.

[0070] The method for forming a workpiece using the above-mentioned waist-lowering and squatting machine tool is as follows:

[0071] Step 1: Set the machine to its initial state (i.e. Figure 14 status shown).

[0072] In this state, the upper die base 1 is at the top dead center position, the top cylinder of the machine tool is in an upward extended state, and the first lower ejector rod 18.1 supports the lower die base 10, so that the lower die base 10 is in the upward limit position.

[0073] Step 2: Place the workpiece 0 to be formed on the forming core 9 and install it on the lower mold base 10, then adjust the machine tool to the compacting and positioning state of the workpiece to be formed ( Figure 16 status shown).

[0074] Specifically, the upper die base 1 moves downward, and the upper ejector rod 19 on the upper die base 1 presses down the middle rod 20 and the second lower ejector rod 18.2, which compresses the top cylinder of the compression machine, and the top cylinder of the machine tool synchronously drives the first lower ejector rod 18.1 to descend. After the first lower ejector rod 18.1 descends, the lower die base 10 loses the support of the first lower ejector rod 18.1, and under the action of the spring 12, the lower die base 10 reaches the limit position of the limit plate 13; at the same time, during the downward movement of the upper die base 1, the upper die insert 4 on the upper die base 1 and the workpiece are in contact with each other. The top inner wall contacts and presses down the workpiece 0, and the movable top plate 3 will exert downward pressure on the top surface of the workpiece, so that the workpiece to be formed is completely inserted downward into the forming inner core 9, and finally the workpiece to be formed is stably positioned between the movable top plate 3, the upper mold insert 4, the forming inner core 9 and the lower mold base 10, wherein the movable top plate 3 and the lower mold base 10 press the top and bottom surfaces of the workpiece to be formed up and down respectively, the upper mold insert 4 presses the top inner wall of the workpiece to be formed, and the forming inner core 9 plays a positioning role on the inner wall of the lower part of the workpiece to be formed.

[0075] Step 3: Waist the workpiece ( Figure 17 status shown).

[0076] Specifically: the upper die base 1 continues to move downward, and the inclined wedge 5 on the upper die base 1 triggers the radial waisting mechanism 8, so that the waisting punch 8.2 of the radial waisting mechanism 8 moves horizontally toward the forming inner core 9, and the workpiece 0 mounted on the forming inner core 9 is waisted until the upper die base 1 contacts the first limiting column 22 on the movable template 7; at the same time, in the waisting process, the movable top plate 3 and the upper mold insert 4 always press the workpiece downward, and the movable top plate 3 and the upper mold insert 4 move to the extreme position of the limiting top plate 2.

[0077] Step 4: Squat the workpiece ( Figure 18 status shown).

[0078] Specifically: after the upper die base 1 contacts the first limiting column 22 on the movable template 7, the upper die base 1 drives the movable template 7 to continue to move downward synchronously; during the movement, the movable top plate 3, the upper mold insert 4, the radial waisting mechanism 8 and the forming inner core 9 descend synchronously (because the bottom expansion cone 11.1 of the positioning support column 11 connected to the forming inner core 9 is movably installed in the limiting groove 17, the depth of the limiting groove 17 is greater than the height of the expansion cone 11.1, so the forming inner core 9 can descend), and the lower die base 10 remains in place due to the limitation of the limiting plate 13, thereby completing the squatting of the workpiece, that is, reducing the height of the workpiece and performing extrusion shaping; the squatting process ends until the upper die base 1 reaches the second limiting column 21 on the lower die base 6.

[0079] Step 5: Machine Tool Return Figure 14 The formed workpiece is unloaded in the initial state.

[0080] Specifically, the upper die base 1 returns to its original position, the machine tool's top cylinder extends upward, and drives the lower die base 10 upward through the first lower ejector rod 18.1. The lower die base 10 pushes the formed workpiece upward to eject the forming core 9; at the same time, the movable top plate 3 pushes the formed workpiece downward under the drive of the first spring mechanism 31, so that the formed workpiece is smoothly separated from the upper die insert 4. The final formed workpiece is shown in the attached figure. Figure 13 .

[0081] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor falls within the scope of protection of the present invention.

Claims

1. A method for forming a cylindrical frame-shaped part, characterized in that: The following steps are involved: Step 1: Punch out a circular sheet from the sheet; Step 2: Using a stretching die, the circular sheet is stretched into a long cylinder with a closed bottom and an open top; Step 3: Continue stretching the long cylinder obtained in step 2 to reduce its diameter and increase its height. The height should be greater than the height of the target product to be formed, leaving a margin. Step 4: stamping and shaping the long cylinder obtained after stretching in step 3 to reduce the R angle of the outward-turned opening at the upper end of the long cylinder and form a flat flange around the R angle, with the flange perpendicular to the cylinder body; Step 5: Cut off the excess flange from the flange, and the cut surface on the flange is perpendicular to the flange plane; Step 6: Flanging the remaining flanges and R corners on the long cylinder to make it a completely long cylinder with equal diameter; Step 7: Punch out the bottom side of the long cylinder to obtain a long cylinder with equal diameter and open at both ends; Step 8, expanding the two ends of the long cylinder obtained in step 7; Step 9, punching the wall of the expanded long cylinder obtained in step 8 to form four equally spaced punching areas on the wall of the long cylinder; Step 10: Rotate the long cylinder at a certain angle and continue punching the wall of the long cylinder from four directions. The punching areas in this step are offset by a certain distance along the circumference of the long cylinder compared to the four punching areas in step 9, and overlap is ensured. After punching in step 10, the four punching areas on the wall of the long cylinder are further expanded compared to step 9. After punching in step 10, four side walls are formed on the wall of the long cylinder with equal spacing along the circumference. Step 11: symmetrically punch out the wall of the long cylinder obtained in step 10 from two directions at 180 degrees apart, punching out two symmetrical side walls; Step 12, finally, the waist-tightening and squatting process is used to shape the long cylinder obtained in step 11, so that the remaining two symmetrical side walls on the wall of the long cylinder are concave inward to the radial size required by the product, and the height of the long cylinder is reduced to the height required by the product.

2. The method for forming a cylindrical frame-shaped part according to claim 1, characterized in that: In step 6, after the flange and R angle are flanging, the top section of the flange is perpendicular to the barrel.

3. The method for forming a cylindrical frame-shaped part according to claim 1, wherein: In step 9, the wall of the expanded long cylinder obtained in step 8 is punched out from four directions at 90 degrees along the circumference of the long cylinder.

4. The method for forming a cylindrical frame-shaped part according to claim 3, wherein: The punching is carried out symmetrically to prevent radial deformation of the long cylinder wall.

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