Parts with extremely small R angle, precision punching die and forming method thereof

Abstract

The present invention discloses a part with a very small R angle, a fine stamping die, and a forming method thereof. The fine stamping die for a part with a very small R angle comprises an upper die and a lower die. The upper die is equipped with a pre-punching punch, a step pin punch, and a male and female die. The pre-punching punch has a concave right angle. The lower die is equipped with a first die insert, a second die insert, a third die insert, and a fourth die insert. The cavity shape of the first die insert is the same as the shape of the pre-punching punch. The cavity shape of the second die insert is the same as the shape of the part. The cavity of the second die insert extends outward from the side corresponding to the right angle area of ​​the part to form an installation groove. The third die insert is installed in the installation groove. The outer wall of the third die insert forms a right angle structure with the inner wall of the second die insert. The cavity shape of the fourth die insert is the same as the strip positioning hole. The fine stamping die proposed by the present invention facilitates the processing of the R angle of the part, simplifies its production process, and ensures the dimensional accuracy of the part.

Description

Technical Field

[0001] The present invention relates to the technical field of fine blanking and forming, and in particular to a part with a very small R angle, a fine blanking die and a forming method thereof. Background Art

[0002] For parts such as the hook needle (made of S20C, 3mm thick) used in electrical switches, the fillet size requirement at the right-angle functional area is extremely high (R0.08±0.08), and the bright band requirement is more than 95%. Figure 1a and Figure 1b If this crochet hook is formed using traditional fine-blanking composite forming, the R0.08±0.08 dimension at the sharp corner can generally only reach R0.2 or above. After forming, the fine-blanked part requires an auxiliary grinding process to remove some material and reduce the R angle, which increases manufacturing costs. If traditional general punching and step forming are used to gradually remove the outer shape, a sharp corner state can be achieved, but the dimensional accuracy of the functional edges on both sides of the R angle is poor, and the bright band requirements cannot be met, which cannot meet the required use. Summary of the Invention

[0003] The main purpose of the present invention is to provide a part with extremely small R angle and its fine blanking die and forming method, aiming to facilitate the processing of the R angle of the fine blanking part, simplify its production process, and ensure the dimensional accuracy of the part.

[0004] To achieve the above object, the present invention provides a fine stamping die for parts with extremely small R angles, comprising an upper die and a lower die, wherein:

[0005] The upper die is equipped with a pre-punching punch for forming the right-angle area of ​​the part, a step-pin punch for forming the positioning hole of the material strip, and a male and female die for forming the outer shape and inner hole of the part. The pre-punching punch has an inward concave right angle to pre-form the R angle of the functional area of ​​the part. The outer contour of the male and female die is the same as the outer shape of the part.

[0006] The lower die is equipped with a first die insert, a second die insert, a third die insert and a fourth die insert. The cavity shape of the first die insert is the same as the shape of the pre-punching punch, the cavity shape of the second die insert is the same as the shape of the part, the cavity of the second die insert extends outward from the side corresponding to the right-angle area of ​​the part to form a mounting groove, the third die insert is installed in the mounting groove to close one side of the cavity of the second die insert, the outer wall of the third die insert and the inner wall of the second die insert form a right-angle structure to correspond to the right-angle area of ​​the part, and the cavity shape of the fourth die insert is the same as the material strip positioning hole.

[0007] Preferably, the upper mold includes an upper mold plate, an upper pad, an upper fixed plate and a gear ring plate arranged in sequence from top to bottom, and the lower mold includes a concave mold plate, a lower fixed plate, a lower pad and a lower mold plate arranged in sequence from top to bottom.

[0008] Preferably, the right-angle area of ​​the part is provided with a first side edge and a second side edge, the first side edge and the second side edge form a right angle, the cavity of the second die insert has a first side wall arranged corresponding to the first side edge, the mounting groove has a second side wall arranged flush with the first side wall, and the two side walls of the third die insert are respectively the third side wall and the fourth side wall, the third side wall is arranged in contact with the second side wall, and the fourth side wall is arranged perpendicular to the first side wall.

[0009] Preferably, the upper die is provided with a first half punching punch for forming a convex burl on the reverse side of the part; and the lower die is provided with a second half punching punch for forming a convex burl on the reverse side of the part.

[0010] Preferably, a push plate for ejecting the part is installed on the lower mold, a countersunk hole is opened on the push plate, a polyurethane rod corresponding to the bulge on the part is installed in the countersunk hole, and the polyurethane rod lifts the bulge to separate the part from the push plate.

[0011] Preferably, a fifth die insert is also installed on the lower die, and the shape and size of the fifth die insert are the same as those of the second die insert. The third die insert is installed at the opening of the fifth die insert, and the pre-punching punch has two concave right angles to pre-form the R angles of two rows of functional areas of parts at the same time.

[0012] Preferably, when the pre-punching punch performs pre-punching of the functional area, the material margin left for the composite blanking of the male and female dies is 0.1 mm to 0.2 mm on one side.

[0013] The present invention further provides a method for forming a part with a very small R angle, comprising the following steps:

[0014] The fine blanking die is used for stamping, and the pre-punching punch of the fine blanking die is matched with the first die insert to form a pre-punched functional area on the material strip, and the positioning hole is formed on the material strip by matching the step pin punch and the fourth die insert;

[0015] The outer shape and inner hole of the part are formed by cooperating the male and female dies with the third die insert and the second die insert to form the composite blanking;

[0016] Deburring parts;

[0017] The parts are sequentially heat treated, sandblasted and PTFE surface treated.

[0018] Preferably, when deburring the parts, a brushing machine is used for automatic processing, and the brushing machine is equipped with a transmission belt with grooves, and the grooves are adapted to the size of the convex buds on the parts.

[0019] The present invention further provides a part with a very small R angle, which is manufactured by the above-mentioned forming method.

[0020] The present invention proposes a fine-blanking die for parts with minimal R angles. A pre-punching punch pre-punches the right-angled area of ​​the part, leaving a small amount of material. This is then refined through the cooperation of a male and female die and a second die insert. This ensures the precision of the right-angled area of ​​the part, ensuring that its brightness (brightness can reach over 95%) and corner radius (R angle less than 0.08) meet the requirements, while also ensuring minimal collapse of sharp corners. Furthermore, this fine-blanking die allows for parts with minimal R angles to be formed in a simple and convenient process (no grinding is required to achieve the right-angled sharp corners), and its manufacturing cost is low (eliminating the grinding process reduces labor costs). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1a Schematic diagram of the top view of the crochet hook;

[0022] Figure 1b Schematic diagram of the side view of the crochet hook;

[0023] Figure 2 Schematic diagram of the structure of the fine blanking die for parts with extremely small R angles of the present invention;

[0024] Figure 3 Schematic diagram of the structure of the concave plate in the fine blanking die for parts with extremely small R angles of the present invention;

[0025] Figure 4 Schematic diagram of the structure of the second die insert and the third die insert in the fine blanking die for parts with extremely small R angles of the present invention;

[0026] Figure 5 Schematic diagram of the structure of the third die insert in the fine blanking die for parts with very small R angles of the present invention;

[0027] Figure 6 Schematic diagram of the arrangement of parts in a fine blanking die for parts with extremely small R angles according to the present invention;

[0028] Figure 7 This is a schematic structural diagram of a push plate in a fine blanking die for parts with extremely small R angles according to the present invention;

[0029] Figure 8 This is a schematic cross-sectional view of the push plate in the fine blanking die for parts with extremely small R angles according to the present invention.

[0030] In the figure, 1-pre-punching punch, 2-step nail punch, 3-convex and concave die, 4-first concave die insert, 5-second concave die insert, 6-third concave die insert, 7-fourth concave die insert, 8-hook needle, 9-upper template, 10-upper pad, 11-upper fixed plate, 12-gear ring plate, 13-concave template, 14-lower fixed plate, 15-lower pad, 16-lower template, 17-first half punching punch, 18-second half punching punch, 19-push plate, 20-polyurethane rod, 21-fifth concave die insert, 22-first side, 23-second side, 24-first side wall, 25-second side wall, 26-third side wall, 27-fourth side wall.

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] It should be noted that in the description of the present invention, the terms "transverse," "longitudinal," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] The present invention provides a fine blanking die for a part with an extremely small R angle (the extremely small R angle refers to R less than 0.08 in a right-angle area of ​​the part).

[0035] Reference Figures 2 to 6 In this preferred embodiment, a fine blanking die for parts with very small R angles includes an upper die and a lower die, wherein:

[0036] The upper die is equipped with a pre-punching punch 1 for forming the right-angle area of ​​the part, a step-pin punch 2 for forming the positioning hole of the strip, and a male and female die 3 for forming the part's outer shape and inner hole. The pre-punching punch 1 has an inward concave right angle to pre-form the R angle of the part's functional area. The outer contour of the male and female die 3 is the same as the part's outer shape.

[0037] The lower die is equipped with a first die insert 4, a second die insert 5, a third die insert 6 and a fourth die insert 7. The shape of the cavity of the first die insert 4 is the same as the shape of the pre-punching punch 1, the shape of the cavity of the second die insert 5 is the same as the shape of the part, the cavity of the second die insert 5 extends outward from the side of the right-angle area of ​​the part to form a mounting groove, the third die insert 6 is installed in the mounting groove to close one side of the cavity of the second die insert 5, the outer wall of the third die insert 6 and the inner wall of the second die insert 5 form a right-angle structure to correspond to the right-angle area of ​​the part (the right-angle structure is used to form the right-angle area of ​​the part), and the shape of the cavity of the fourth die insert 7 is the same as the shape of the strip positioning hole.

[0038] Because the right-angle area of ​​the hook needle 8 requires R < 0.08, and the R angle in the drawing dimension is close to a right angle, if the cavity is directly opened on the second die insert 5 without the third die insert 6, the cavity needs to be formed by wire cutting when the second die insert 5 is manufactured. When using wire cutting to cut the cavity, there will be a radius of at least R0.2. Therefore, this second die insert 5 cannot ensure that the right angle tolerance of the part after stamping meets the requirements. Therefore, in this embodiment, the second die insert 5 and the third die insert 6 are spliced ​​to form a right-angle structure (the outer side wall of the third die insert 6 is easy to machine, and the one side of the second die insert 5 extends outward in a straight line, which is also easy to machine), achieving the purpose of no R angle or a very small R angle.

[0039] Specifically, refer to Figure 2 The upper mold includes an upper mold plate 9, an upper pad 10, an upper fixed plate 11 and a gear ring plate 12 arranged in sequence from top to bottom, and the lower mold includes a concave mold plate 13, a lower fixed plate 14, a lower pad 15 and a lower mold plate 16 arranged in sequence from top to bottom.

[0040] In this embodiment, refer to Figure 1a 、 Figures 3 to 6 The right-angle area of ​​the part is provided with a first side 22 and a second side 23, and the first side 22 and the second side 23 form a right angle. The cavity of the second die insert 5 has a first side wall 24 corresponding to the first side 22, and the mounting groove has a second side wall 25 flush with the first side wall 24 (the two are located in the same straight line). The two side walls of the third die insert 6 are respectively a third side wall 26 and a fourth side wall 27. The third side wall 26 is fitted with the second side wall 25, and the fourth side wall 27 is perpendicular to the first side wall 24 (thereby forming a right-angle structure).

[0041] Specifically, the pre-punching punch 1 has a third side and a fourth side (the third side and the fourth side form a concave right angle), the third side is flush with the first side 22, the fourth side is flush with the second side 23, and the length of the fourth side is less than the length of the second side 23 (refer to Figure 6 can be seen).

[0042] Further, refer to Figure 2 The upper die is equipped with a first half punch 17 for forming the convex bud on the back of the part; the lower die is equipped with a second half punch 18 for forming the convex bud on the front of the part. Because this part (i.e., the hook 8) has convex buds on both the front and back sides, the first half punch 17 and the second half punch 18 are used to form the two convex buds respectively. Figure 1a The dotted hole shows the location of the reverse convex bract.

[0043] Further, refer to Figure 7 and Figure 8 A push plate 19 for ejecting the part is installed on the lower mold. A countersunk hole is opened on the push plate 19. A polyurethane rod 20 corresponding to the bulge on the part is installed in the countersunk hole. The polyurethane rod 20 lifts the bulge to separate the part from the push plate 19.

[0044] In the prior art, a commonly used ejection method for fine stamping dies is to set a floating ejector pin on the plane of the push plate 19, separate the part from the push plate 19, and then blow out the die surface under the action of high-pressure gas blown out by an air gun. This method will leave a raised ejector pin mark with a height of about 0.02 mm on the part.

[0045] Because this part is not allowed to have spring-top nail marks, the designed top piece solution is: this product has a φ3mm high 0.5mm bulge, and the φ4 clearance hole of the bulge on the push plate 19 is drilled to a depth of 8mm. A φ4 polyurethane rod 20 is installed in this countersunk hole, flush with the push plate 19. After the part is punched out, the polyurethane rod 20 will push the bulge to separate the part from the push plate 19. Installing the polyurethane rod 20 in this deep countersunk hole can not only make the bulge give way, but also will not produce raised spring-top nail marks on the part. The height and diameter of the bulge will not change in size under the force of the polyurethane rod 20.

[0046] Further, refer to Figure 3 The lower die is also equipped with a fifth die insert 21. Its shape and size are identical to those of the second die insert 5. A third die insert 6 is mounted at the opening of the fifth die insert 21. The pre-punching punch 1 has two inwardly concave right angles to simultaneously preform the rounded corners of the functional areas of two rows of parts. This fine-blanking die can now form two rows of parts, one above the other.

[0047] Furthermore, when the pre-punching punch 1 performs pre-punching of the functional area, the material margin left for the composite blanking of the male and female dies 3 is 0.1 mm to 0.2 mm on one side.

[0048] by Figure 1a and Figure 1b The crochet needle 8 shown is taken as an example to illustrate the working process of the fine punching die.

[0049] Step 1: Punch the step-distance nail holes (forming positioning holes), half-punch the countersunk convex buds (including the convex buds on the front and back), punch the pre-cut holes in the functional area (that is, the pre-cut holes are Figure 5 At D in the middle, the irregular pre-cut hole has two right angles, and a right angle can be pre-cut simultaneously for the upper and lower rows);

[0050] Step 2: Positioning the step pins and empty steps;

[0051] Step 3: Positioning of pitch nails and compound blanking (the top piece);

[0052] Step 4: Positioning the step pins and empty steps;

[0053] Step 5: Positioning of pitch pins and compound blanking (the next piece).

[0054] In the first working step, the pre-punching punch 1 and the step pin punch 2 punch holes in the material strip. The blanking clearance between the pre-punching punch 1 and the first die insert 4 is 0.05mm; the blanking clearance between the step pin punch 2 and the fourth die insert 7 is 0.05mm. The pre-punching punch 1 and the step pin punch 2 are guided by the gear ring plate 12 and slide with the gear ring plate 12, with a single-side assembly clearance of 0.005mm; the assembly clearance with the upper fixed plate 11 (1) is 0.05mm. The first die insert 4 is built into the die plate 13, with no clearance, providing pre-tightening force for the die cavity and ensuring dimensional stability. The pre-cut holes and positioning pin holes are both punched with small clearances, and the die cutting edge can be slightly chamfered to ensure the bright band of the punched surface and the life of the cutting edge. The first half punching punch 17 is guided by the gear ring plate 12, and the second half punching punch 18 is guided by the concave template 13. At the same time, the material is extruded under the action of the blanking force, and the extruded material will form a convex bulge on the back of the hole.

[0055] The second and fourth steps are idle steps, without punching and forming. They are mainly used to ensure the distance between the concave mold cavities, thereby ensuring the strength of the entire concave mold assembly.

[0056] In the third and fifth steps, the pitch pins are used to accurately position the material in the pitch pin holes. The single-side gap between the positioning pins and the positioning pin holes is 0.005mm-0.01mm. Under the action of the punch and die 3 and the second die insert 5 (or the fifth die insert 21), the composite blanking is completed together, and the part shape and hole are punched out at the same time. The punching gap between the punch and die 3 and the second die insert 5 (or the fifth die insert 21) is 0.015mm. The second die insert 5 and the fifth die insert 21 are both inlaid structures, and the third die insert 6 is a spliced ​​insert. The second die insert 5 and the third die insert 6 form an absolute right angle after splicing. Only after completing the punching can the part reach R < 0.08. It is preferred that the functional area pre-punching leaves a single-side allowance of 0.15mm for the composite blanking. Through small allowance finishing, the bright band of the part blanking surface is ensured to be > 90%, and at the same time, the material deformation during blanking is reduced to achieve a small collapse angle at a sharp angle.

[0057] The fine-blanking die for parts with very small R angles proposed in this embodiment pre-punches the right-angle area of ​​the part using a pre-punching punch 1, leaving a portion of material to be left. The die is then fine-trimmed using the cooperation of the male and female dies 3 and the second die insert 5. This ensures the accuracy of the right-angle area of ​​the part, ensuring that its brightness (brightness can reach over 95%) and rounded corners (R angle less than 0.08) meet the requirements, while also ensuring a small collapse angle at the sharp corners. Furthermore, the fine-blanking die for forming parts with very small R angles is simple and convenient (no grinding is required to achieve the right-angle sharp corner state), and its manufacturing cost is low (eliminating the grinding process reduces labor costs).

[0058] The present invention further provides a method for forming a part with a very small R angle.

[0059] In this preferred embodiment, a method for forming a part with a very small R angle includes the following steps:

[0060] Step S10, punching is performed by the fine punching die of the above embodiment, and the pre-punching punch 1 of the fine punching die is matched with the first die insert 4 to form a pre-punching functional area (for Figure 5 At point D in the middle), a positioning hole is formed on the material strip by the step pin punch 2 and the fourth die insert 7;

[0061] Step S20, the male and female molds 3 cooperate with the third die insert 6 and the second die insert 5 to perform composite blanking to form the outer shape and inner hole of the part;

[0062] Step S30, deburring the parts;

[0063] In step S40 , the parts are sequentially subjected to heat treatment, sandblasting, and PTFE (Poly tetrafluoroethylene) surface treatment.

[0064] In step S20 , the outer shape and the inner hole of the part are fine-blanked in the same working step, and the forming accuracy is high, which can meet the dimensional accuracy requirements of the crochet hook 8 .

[0065] In step S30, when deburring the parts, a brushing machine is used for automatic processing. The brushing machine is equipped with a transmission belt with grooves, and the grooves are adapted to the size of the convex buds on the parts.

[0066] By setting grooves to accommodate the bulges on the back of the parts, a brushing machine can be used to automatically remove burrs. Compared with traditional manual file deburring, the deburring efficiency can be greatly improved.

[0067] During heat treatment of the part, since the surface is the functional surface of the hook needle 8, it requires surface wear resistance and good core toughness. In this example, S20C, which has undergone spheroidizing annealing and has low strength, is used. Carbonitriding heat treatment improves the strength requirements of the product's center and surface. The heat treatment technical requirements are: effective hardened layer depth CHD550HV0.30.15-0.25, surface hardness 700-800HV0.3, and core hardness 180-450HV5. The production equipment uses a multi-purpose furnace or mesh belt furnace, ensuring stable heat treatment quality.

[0068] Sandblasting is a process that precedes surface treatment. Sandblasting can remove all impurities, including scale, from the workpiece surface before coating, plating, or bonding. This leaves the workpiece free of sharp edges, burrs, scale, and rust, and establishes a crucial foundational pattern (commonly known as a rough surface) on the workpiece surface. Furthermore, by using abrasives of varying grit sizes, such as those from Feizhan Abrasives, varying degrees of roughness can be achieved, significantly improving the bond between the workpiece and the coating or plating material. Sandblasting can also ensure a stronger, higher-quality bond between bonded parts.

[0069] When applying PTFE surface treatment to parts, the technical requirements for surface treatment are: the surface of the part should be black, with a uniform coating, no white spots, bubbles, cracks, bruises, missing materials, white spots, or other appearance defects; adhesion test: the special adhesive tape should not fall off when pulled. The processing method is spray coating, and the surface treatment quality is stable.

[0070] The present invention proposes a forming method for parts with extremely small R angles. While ensuring the dimensional accuracy of the parts (the sharp corners have high precision and the brightness can reach more than 90%), the forming process is simple and convenient (no grinding is required to achieve a right-angle sharp corner state) and the manufacturing cost is low (reducing the grinding process and thus reducing labor costs).

[0071] The present invention further provides a component with a very small R angle.

[0072] In this preferred embodiment, a part with a very small R angle is made using the above-mentioned molding method.

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A fine blanking die for parts with very small R angle, characterized in that: It includes an upper die and a lower die, wherein: The upper die is equipped with a pre-punching punch for forming the right-angle area of ​​the part, a step-pin punch for forming the positioning hole of the material strip, and a male and female die for forming the outer shape and inner hole of the part. The pre-punching punch has an inward concave right angle to pre-form the R angle of the functional area of ​​the part. The outer contour of the male and female die is the same as the outer shape of the part. The lower die is equipped with a first die insert, a second die insert, a third die insert and a fourth die insert. The shape of the cavity of the first die insert is the same as the shape of the pre-punching punch, the shape of the cavity of the second die insert is the same as the shape of the part, the cavity of the second die insert corresponds to the side of the right-angle area of ​​the part and extends outward to form a mounting groove. The third die insert is installed in the mounting groove to close one side of the cavity of the second die insert. The outer wall of the third die insert and the inner wall of the second die insert form a right-angle structure to correspond to the right-angle area of ​​the part. The shape of the cavity of the fourth die insert is the same as the strip positioning hole; the right-angle area of ​​the part is provided with a first side edge and a second side edge, the first side edge and the second side edge form a right angle, the cavity of the second die insert has a first side wall corresponding to the first side edge, the mounting groove has a second side wall flush with the first side wall, and the two side walls of the third die insert are respectively a third side wall and a fourth side wall, the third side wall is fitted with the second side wall, and the fourth side wall is perpendicular to the first side wall.

2. The fine blanking die for parts with extremely small R angles according to claim 1, characterized in that: The upper mold includes an upper mold plate, an upper pad, an upper fixed plate and a gear ring plate arranged in sequence from top to bottom, and the lower mold includes a concave mold plate, a lower fixed plate, a lower pad and a lower mold plate arranged in sequence from top to bottom.

3. The fine blanking die for parts with extremely small R angles according to claim 1, characterized in that: The upper die is provided with a first half punching punch for forming a convex burl on the reverse side of the part; the lower die is provided with a second half punching punch for forming a convex burl on the reverse side of the part.

4. The fine blanking die for parts with extremely small R angles according to claim 3, characterized in that: The lower die is provided with a push plate for ejecting the part. The push plate is provided with a countersunk hole in which a polyurethane rod corresponding to the bulge on the part is installed. The polyurethane rod lifts the bulge to separate the part from the push plate.

5. The fine blanking die for parts with extremely small R angles according to claim 1, characterized in that: A fifth die insert is also installed on the lower die. The shape and size of the fifth die insert are the same as those of the second die insert. The third die insert is installed at the opening of the fifth die insert. The pre-punching punch has two inwardly concave right angles to pre-form the R angles of two rows of functional areas of parts at the same time.

6. The fine blanking die for parts with very small R angles according to any one of claims 1 to 5, characterized in that: When the pre-punching punch performs pre-punching on the functional area, the material margin left for the composite blanking of the male and female dies is 0.1 mm to 0.2 mm on one side.

7. A forming method for parts with extremely small R angles, characterized in that: The following steps are involved: Performing stamping by the fine blanking die according to any one of claims 1 to 6, cooperating the pre-punching punch of the fine blanking die with the first die insert to form a pre-punched functional area on the material strip, and cooperating the step pin punch with the fourth die insert to form a positioning hole on the material strip; The outer shape and inner hole of the part are formed by cooperating the male and female dies with the third die insert and the second die insert to form the composite blanking; Deburring parts; The parts are sequentially heat treated, sandblasted and PTFE surface treated.

8. A forming method for parts with extremely small R angles according to claim 7, characterized in that: When deburring parts, a brushing machine is used for automatic processing. The brushing machine is equipped with a transmission belt with grooves that match the size of the convex buds on the parts.

9. A part with a very small R angle, characterized in that: Made by the molding method described in claim 7.

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