Novel negative-angle bending die for steel plate

Abstract

The utility model belongs to the field of vehicle sheet metal part forming and manufacturing, and provides a novel steel plate negative angle bending die which comprises an upper die plate (1), a lower die plate (9), a male die (4), a fixed female die (10) and a movable female die (11), the upper portion of the male die (4) is T-shaped and clamped into a space formed by two male die fixing plates (5), the section of the lower portion of the male die (4) is provided with two round corners, and the lower portion of the male die (4) is provided with two round corners. The fixed female die (10) is provided with two movable female dies (11), each movable female die (11) is in a notch disc shape, the movable female dies (11) are embedded into the fixed female die (10), the bottom of the male die (4) can be embedded into notches in the movable female dies (11), and a gap between the lower portion of the male die (4) and the inner walls of the notches of the movable female dies (11) can accommodate the thickness of a steel plate. According to the utility model, one set of die can complete two processes of production; the production efficiency of products is effectively improved, the material size can be effectively guaranteed, and the problems of springback and cracks are solved.

Description

Technical Field

[0001] The utility model belongs to the field of forming and manufacturing of vehicle sheet metal parts, and in particular relates to a new type of steel plate negative angle bending die, which is suitable for forming and processing of vehicle sheet metal parts. Background Art

[0002] In the prior art, Figure 1 The workpiece shown in the figure is processed. Its material is Q235 steel plate, with a material thickness of 3mm, a material length of 174mm, a bending height of 34mm, a bending angle of 35°, and a bending inner diameter of R=10mm. According to previous ideas, the first step in designing molds for such products is to bend at right angles: for products, the two sides are first bent along the bending line using a bending machine, and it is necessary to calculate the unfolded material and the bending size; the second step is to complete the negative angle bending: using a press and a separate arc template for bending, operators are required to repeatedly install the mold operation, with low production efficiency and poor appearance quality. In addition, due to problems such as material performance and springback, parts produced by the original process are prone to cracks at the bend corners. Utility Model Content

[0003] In order to solve the problems existing in the above-mentioned prior art, the utility model proposes a new type of steel plate negative angle bending mold, comprising an upper template (1), a lower template (9), a punch (4), a fixed die (10) and a movable die (11), a guide column (8) and a guide sleeve (7) are arranged between the upper template (1) and the lower template (9), the guide sleeve (7) and the upper template (1) are fixed by an interference fit, the guide column (8) and the lower template (9) are fixed by an interference fit, the guide column (8) is inserted into the guide sleeve (9), a screw (2) passes through the upper template (1) and the pad (3) to fix the punch fixing plate (5) below the upper template (1), the punch fixing plate (5) is two L-shaped plates, and the two punches are fixed to the lower template (1). The fixing plate (5) fixes the punch (4) below the backing plate (3). The upper part of the punch (4) is T-shaped. The upper part of the punch (4) is inserted into the space formed by the two punch fixing plates (5). The cross section of the lower part of the punch (4) has two rounded corners. The fixed die (10) is fixed to the lower mold plate (9) by screws (14). The fixed die (10) is a symmetrical structure and is equipped with two movable dies (11). The movable die (11) is a notched disc. The movable die (11) is embedded in the fixed die (10). The bottom of the punch (4) can be embedded in the notch on the movable die (11). The gap between the lower part of the punch (4) and the inner wall of the notch of the movable die (11) can accommodate the thickness of the steel plate.

[0004] Furthermore, the upper mold plate (1), the backing plate (3) and the punch fixing plate (5) are fixed by interference fit using pins (6).

[0005] Furthermore, a spring (12) and a chuck (13) are arranged on the movable die (11); a circular hole on the chuck (13) is hooked on a convex shaft 1 on the fixed die (10); another circular hole on the chuck (13) is hooked on a central axis of the movable die (11); the convex shaft and the central axis are equidistant from the bottom surface of the lower die plate (9); one end of the spring (12) is hooked on the convex shaft 1; the other end of the spring (12) is hooked on a convex shaft 2 on the movable die (11); the convex shaft 2 is close to the circumference and the notch.

[0006] Furthermore, the fillet angle of the lower portion of the punch (4) is greater than 20° and less than 90°.

[0007] Furthermore, the fillet angle of the lower part of the punch (4) is equal to 32°.

[0008] Furthermore, when the workpiece is bent for the second time, the ratio of R / t is less than 5, wherein R is the bending radius and t is the thickness of the workpiece.

[0009] Furthermore, when the workpiece is bent for the second time, the bending radius R is 13 mm and the bending angle is 32°.

[0010] Furthermore, the upper portion of the fixed die (10) is stepped, the upper opening of the fixed die (10) can accommodate the lower portion of the punch (4), and there is a gap between the upper portion of the fixed die (10) and the lower portion of the punch (4) to accommodate the thickness of the workpiece. When the die bends the workpiece, the workpiece is first bent 90 degrees, the die continues to move downward, and the workpiece touches the lower cutting edge of the movable die (11), causing the movable die (11) to start rotating. When the lower cutting edge rotates to be flush with the fixed die (10), the workpiece is pressed. When the workpiece moves upward with the punch (4) and leaves the movable die (11), the workpiece rebounds, so that it is separated from the punch (4) and does not contact it.

[0011] The utility model breaks away from the previous processing method of first using a bending machine and then processing again, ensuring that one set of molds completes the production of two processes; effectively improving product production efficiency, reducing production costs, and reducing the labor intensity of operators. The new mold can effectively ensure the material size after production and solve the problems of rebound and cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the front view of the product;

[0013] Figure 2 This is the side view of the product;

[0014] Figure 3This is a structural diagram of the utility model, wherein: 1. upper template, 2. screw 1, 3. pad, 4. punch, 5. punch fixing plate, 6. pin, 7. guide sleeve, 8. guide column, 9. lower template, 10. fixed die, 11. movable die, 12. spring, 13. chuck, 14. screw 2;

[0015] Figure 4 This is the first step of bending schematic diagram;

[0016] Figure 5 This is the schematic diagram of the second step bending;

[0017] Figure 6 This is the schematic diagram for the second step of bending. DETAILED DESCRIPTION

[0018] In order to better understand the purpose, technical solution and function of the utility model, the following Figure 1-6 , the utility model is further described in detail, but the utility model can be implemented in a variety of different ways as defined and covered by the claims. The drawings constituting a part of this application are used to provide a further understanding of the utility model, and the illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an improper limitation of the utility model.

[0019] The overall idea of ​​designing the new mold of this utility model is:

[0020] 1. Optimize the mold structure and propose a new processing method for negative angle bending of steel plates. Through compound mold stamping, the negative angle bending of the product can be achieved in one step.

[0021] 2. Pay attention to the human-machine environment design, the mold is easy to use, the operation process is simplified, safe and fast, and the labor intensity of the operator is reduced.

[0022] 3. The mold adopts a secondary bending structure, which first performs right-angle bending and then negative-angle bending. The bending is divided into two steps to solve the problem of large material springback. The mold structure is compact and perfect in design, which shortens the production and processing cycle, reduces the mold cost, ensures the completion of mass production, and improves production efficiency.

[0023] After the overall idea of ​​mold design is determined, the first step is to analyze and calculate the blank size, bending force, and resilience of the material, and analyze the feasibility of completing two processes at one time.

[0024] Determine the mold structure

[0025] 1. Develop the following plan: Since the product is a negative-angle bend, it is necessary to first bend the two sides of the material at a right angle, and then bend at a negative angle. Bending in two steps can effectively reduce the problem of material rebound. When bending, the punch moves downward, and the fixed die first bends the blank into a U shape. When the punch continues to press down, the movable dies on both sides begin to rotate, so that the blank is finally bent into a U-shaped part with a bending angle of 35°. After the bending is completed, the punch rises, and cooperates with the spring to reset the movable die, and the workpiece is taken out by the punch. Due to the increase in the angle caused by the rebound of the material, the workpiece can be taken out from the side of the punch; the entire mold structure adopts a combination of movable die and fixed die, which is novel in design, simple and practical, and convenient for production.

[0026] 2. Determine the equipment to be used for the mold: Based on the required force, mold structure requirements, and the equipment limitations of our factory, as well as the advantages of the hydraulic press, which has a slow working speed, a pressure-maintaining function, and will not be overloaded, the YH27-500T hydraulic press is comprehensively selected.

[0027] 1. Process analysis and process plan formulation

[0028] 1.1 Part shape analysis

[0029] like Figure 1 As shown, the overall shape of the product is sheet metal forming. The difficulty in processing the product lies in the 35° negative angle bend. The product length is 174mm, and the workpiece can be processed by a press mold.

[0030] 1.2 Mechanical properties analysis

[0031] Q235 steel material is used, and the specific mechanical properties are shown in Table 1:

[0032] Table 1 Q235 steel material properties

[0033] Material Name Shear strength(Mpa) Tensile strength(Mpa) Yield point(Mpa) Elongation(%) Q235 141-188 370-500 235 25

[0034] 1.3 Blank expansion

[0035] The unfolded size of the material should be the size of the neutral layer position of the bend, and the radius of the neutral layer is:

[0036] ρ=R+Kt,

[0037] Where: ρ is the neutral layer radius (mm), R is the inner radius of the bend (mm), K is the neutral layer position coefficient, and t is the material thickness (mm). According to the document "Die Design Manual", the neutral layer position coefficient is 0.2997. Taking 0.3, we can get the neutral layer radius of 11.5mm. Based on this, we can know that the blank size of the material should be 3×174×179mm.

[0038] 1.4 Process plan confirmation

[0039] The optional process solutions include single-step solution, compound die solution and progressive die solution.

[0040] Single process solution: one station produces one process. Two bends and two sets of dies complete the two-step process of the workpiece.

[0041] Compound die solution: One station completes multiple processes. Two bends are compound pressed at the same time.

[0042] Progressive die solution: two processes are completed on multiple stations. All processes of two bends are completed on one die.

[0043] Determination of the plan:

[0044] Single process solution: If this solution is selected for production, only one process can be processed at a time. First, the 90° bend of the workpiece is processed. The separated shape is manually placed on another mold for secondary bending. The manufacturing process is simple, but when mass production is carried out, the back and forth changes of the mold will increase time and labor costs. The accuracy of the back and forth mold changes is not guaranteed, so this solution is not suitable for mass production.

[0045] Compound die solution: If this solution is selected for production, one die completes the two bending processes of the workpiece. The compound die cost and structure are more complicated than solution one. However, the products produced by the compound die are more precise and the quality of the parts is better than solution one. It is more suitable for mass production and can effectively improve the efficiency of the product. This solution can be used for production.

[0046] Progressive die solution: If this solution is selected for production, only one set of dies is needed to complete all the processes of the workpiece. It is more expensive than solution 1 and the dies are more complicated. However, it is more efficient than solution 1 and more accurate than solution 2. It can also meet the precision requirements of blanking parts, but it is more expensive than solution 2 and the material requirements are stricter than solution 2. Although this solution is feasible from the perspective of cost, it is not as cost-saving as solution 2.

[0047] To sum up, the composite die is finally selected for blanking the workpiece.

[0048] 1.5 Forming force calculation

[0049] 1.5.1 Calculation of bending force

[0050] When the die is bent for the first time, the bending force is calculated by the following formula:

[0051] F Z1 =b1t2R m / (r+t),

[0052] In the formula, F Z1is the free bending force of the material at the end of the punching stroke (N); b1 is the width of the bent part (mm); t is the thickness of the bent part (mm); R m is the tensile strength (MPa); r is the bending radius (mm); b1 = 179 mm; R m =500MPa; r = 11.5mm; t = 3mm, we can calculate:

[0053] F Z1 =55551.72(N).

[0054] When the die is bent for the second time, the bending force is calculated by the following formula:

[0055] F Z2 =b2t 2 R m / (r+t),

[0056] In the formula, b2 = 109 mm, and the calculation is:

[0057] F Z2 =33827.58(N),

[0058] 1.5.2 Calculation of top piece force

[0059] The ejector force is calculated by the following formula:

[0060] F D =C D (F Z1 +F Z2 ),

[0061] In the formula, F D C is the ejection force required for the material (N); D F is the top piece force coefficient; Z1 、F Z2 C is the free bending force of the material at the end of the stamping stroke during the first and second bending of the die (N); D =0.2; calculated:

[0062] F D =17875.86(N),

[0063] When bending the part, the selection of the press tonnage needs to consider the size of the bending force and the pressing force, that is:

[0064] F 压机 ≥1.2(F D +F Z1 +F Z2 ),

[0065] That is, F 压机 ≥128706.19(N),

[0066] Based on the above conditions, mold structure requirements and equipment limitations of our factory, as well as the advantages of the hydraulic press, which has a slow working speed, pressure-maintaining function and will not be overloaded, the YH27-500T hydraulic press was comprehensively selected.

[0067] 1.6 Springback calculation

[0068] The workpiece is bent twice. The bending size is not required for the first bending. The R / t ratio is less than 5 for the second bending. The springback amount can be controlled by using the gap between the male and female dies. Considering comprehensively, the bending radius R of the second bending is 13mm and the bending angle is designed to be 32°.

[0069] 2. Design of new mold for negative angle bending

[0070] 2.1 Selection of the overall mold structure

[0071] The problem with the bending of this part is that negative angle bending using a traditional bending machine will result in interference, and the bending machine can only bend at angles above 90°.

[0072] 2.2 Innovative mold solutions

[0073] 2.2.1 Since one-time bending is prone to cause cracks in the material and large springback problems, we innovatively use a two-time bending method, first performing a right-angle bend and then a secondary bend.

[0074] 2.2.2 The difficulty of negative angle bending lies in how to prevent interference between the material and the mold, so a movable die is used. When the material is pressed down by the punch, the movable dies on both sides will rotate accordingly, so that the blank is finally bent into a U-shaped part with an angle less than 90°.

[0075] 2.2.3 The unloading problem of negative angle bending. After the die is pressed, the punch moves upward, the movable die rotates, and the workpiece leaves the die. At the same time, due to the small rebound of the workpiece, the workpiece will naturally separate from the punch, and you only need to take the workpiece out from the side.

[0076] The mold designed in the utility model comprises an upper mold plate (1), a lower mold plate (9), a punch (4), a fixed die (10) and a movable die (11); a guide post (8) and a guide sleeve (7) are arranged between the upper mold plate (1) and the lower mold plate (9); the guide sleeve (7) and the upper mold plate (1) are fixed by an interference fit; the guide post (8) and the lower mold plate (9) are fixed by an interference fit; the guide post (8) is inserted into the guide sleeve (9); a screw (2) passes through the upper mold plate (1) and a backing plate (3) to fix a punch fixing plate (5) below the upper mold plate (1); the punch fixing plate (5) is two L-shaped plates; the two punch fixing plates (5) together fix the punch (4) The upper part of the punch (4) is T-shaped and is inserted into the space formed by two punch fixing plates (5). The cross section of the lower part of the punch (4) has two rounded corners. The fixed die (10) is fixed to the lower template (9) by screws (14). The fixed die (10) is a symmetrical structure and is equipped with two movable dies (11). The movable die (11) is a notched disc. The movable die (11) is embedded in the fixed die (10). The bottom of the punch (4) can be embedded in the notch on the movable die (11). The gap between the lower part of the punch (4) and the inner wall of the notch of the movable die (11) can accommodate the thickness of the steel plate. The upper template (1), the pad (3) and the punch fixing plate (5) are fixed by interference fit through pins (6). A spring (12) and a chuck (13) are arranged on the movable die (11); a circular hole on the chuck (13) is hooked on a convex shaft 1 on the fixed die (10); another circular hole on the chuck (13) is hooked on a central axis of the movable die (11); the convex shaft and the central axis are equidistant from the bottom surface of the lower die plate (9); one end of the spring (12) is hooked on the convex shaft 1; the other end of the spring (12) is hooked on a convex shaft 2 on the movable die (11); the convex shaft 2 is close to the circumference and the notch.

[0077] 2.3 Design of main components

[0078] 2.3.1 Design of male and female dies

[0079] After the mold structure is determined, the design of the male and female molds is the key to the design of the entire mold. Since a movable female mold is to be designed, the size of the fixed female mold needs to be larger. In the case of large-scale workpiece production, the mold life needs to be longer, so it is necessary to ensure that the female mold does not have too much wear. In this design, since the movable female mold needs to rotate in the mold, it needs to be lubricated, and the stamping speed cannot be too fast.

[0080] The processing of the workpiece is divided into two steps. The first step is to bend the workpiece 90°, so the upper part of the fixed die is designed to be stepped, and the workpiece is bent to 90° using the die edge R5. The second step requires negative angle bending. When the workpiece continues to move downward, it first touches the lower edge of the active die, causing the active die to start rotating. When the lower edge rotates to the same level as the fixed die, the workpiece is pressed. After the workpiece moves upward with the punch and leaves the active die, the workpiece rebounds, leaving it out of contact with the punch, and the calculated rebound amount can make the workpiece more accurate, reaching an internal angle of 35°. Generally speaking, the fillet angle of the lower part of the punch is greater than 20° and less than 90°.

[0081] 2.3.2 Design of male and female die fixing

[0082] The choice of fixing method when designing the mold is also important. This mold is fixed with steps, and then the fixing plate and the upper mold are fixed with screws and pins.

[0083] 2.3.3 Dimensions of the working parts of the male and female dies

[0084] Fixed die corner radius r p The value is determined to be 5mm based on the ratio of the radius of the workpiece when it is bent to the thickness of the workpiece.

[0085] The outer circle size of the movable die must meet the external dimensions required for negative angle bending, the assembly relationship of the spring, the axis and other components, and the stability of the component in the fixed die. Therefore, clearance fit is required. Finally, it is confirmed as

[0086] The fillet radius of the punch r d

[0087] This dimension has a great influence on the bending process of the workpiece. After springback calculation, the value obtained is r d =13mm.

[0088] Gap between male and female molds

[0089] The gap value c of the bending die has an impact on the quality of the bent part, the life of the bending die and the bending force. The larger the gap, the greater the springback and the lower the workpiece precision, but the bending force is reduced, which is conducive to extending the life of the bending die; too small a gap will cause the material to become thinner, increase the friction between the material and the die, and reduce the life of the die. Therefore, c = 1.1t, that is, c = 3.3.

[0090] Mould depth L o

[0091] Due to the use of a movable die structure, the depth of the mold should be increased to 130mm.

[0092] 2.3.4 Spring selection

[0093] The spring positioning should be determined to meet the requirements that one end should be on the same horizontal line of the axis of the movable die, and the other end should be fixed on the movable die. When the mold is not started, the spring should be in an unstretched state. Based on this, the spring selected is LⅡ-B-2×10×75-GB / T2008-HT.

[0094] 2.3.5 Chuck design

[0095] The chuck is used to determine the relative position of the rotating axis of the movable die and one end of the spring. ) can keep rotating, so the size of one end is selected as The tolerance fit allows the shaft to rotate.

[0096] 2.3.6 Selection of standard parts

[0097] Guide pins, guide sleeves, screws, pins, springs, etc. are selected as standard parts according to the international standard manual and cold stamping die standard manual.

[0098] 2.4 Selection of materials for main components

[0099] 2.4.1 Selection of convex and concave die materials

[0100] Since the movable die needs to rotate in the die, considering the service life of the die, the materials of both the male and female dies are selected from Cr12MoV tool steel with high hardenability, hardness, wear resistance and plasticity, small deformation and low price, which is suitable for stamping dies; heat treatment hardness: 58~62HRC.

[0101] 2.4.2 Pad material

[0102] The pad is made of 45 steel with high strength, good plasticity and toughness and low cost; heat treatment hardness: 40~45HRC.

[0103] 2.4.3 Material of the punch fixing plate

[0104] The punch fixing plate is made of 38CrSi with good hardenability, high strength and wear resistance; heat treatment hardness: 38~42HRC.

[0105] 2.4.4 Other component materials

[0106] The materials of other parts of the mold are carbon structural steel Q235, which has low production cost.

[0107] 2.5Main parts processing requirements

[0108] 2.5.1 Design requirements for male and female dies

[0109] When the male and female dies are combined, the assembly clearance is required to be controlled between 0.2 and 0.3 mm, and the flatness is required to be within the range of 0.3 to 0.5 mm. When making various female and male dies, the shape is first roughly milled, and then quenched to 58 to 62 HRC after drilling and tapping, and the working part size is then fine-machined. After the male and female dies are processed by the equipment, they need to be polished and ground to ensure the finish requirements and improve product quality.

[0110] 2.6 Closing height of mold

[0111] The mold closing height refers to the distance between the upper and lower mold bases when the mold is in the lowest working position. It should also be adapted to the mold loading height of the press.

[0112] The closing height of this set of molds = upper mold plate + pad + punch + 3 + die - 70 = 235mm.

[0113] 2.7 Mould working process

[0114] At the beginning of the working stroke, the upper die moves downward, and the punch 4 and the fixed die 10 first bend the blank into a U shape. When the punch 4 continues to press down, the movable dies 11 on both sides begin to rotate inward, driving the spring 12 to stretch, so that the blank is finally pressed into a U-shaped part with a bending angle less than 90°. Then the punch 4 rises, and the movable die 11 is reset under the joint action of the spring 12 and the punch 4, and the workpiece is removed from the punch 4 in a direction perpendicular to the drawing. The stamping process is completed, and the two-step production of a single piece is completed at one time, and the negative angle bending is directly completed.

[0115] The utility model has the following beneficial effects:

[0116] 1. Optimize the mold structure. One set of composite mold completes two bending steps and two processes, which simplifies the operation process, improves product precision, and increases production efficiency by 2 times. At the same time, the problem of springback is taken into consideration, effectively improving the molding accuracy.

[0117] 2. The innovative processing method of combining movable die with fixed die is adopted, which provides new ideas and methods for future molding.

[0118] 3. Pay attention to the human-machine environment design, the mold is easy to use, the operation process is simplified, safe and fast, and the labor intensity of the operator is reduced.

[0119] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A new type of steel plate negative angle bending die, characterized in that: The invention comprises an upper mold plate (1), a lower mold plate (9), a punch (4), a fixed die (10) and a movable die (11); a guide post (8) and a guide sleeve (7) are arranged between the upper mold plate (1) and the lower mold plate (9); the guide sleeve (7) and the upper mold plate (1) are fixed by an interference fit; the guide post (8) and the lower mold plate (9) are fixed by an interference fit; the guide post (8) is inserted into the guide sleeve (7); a screw (2) passes through the upper mold plate (1) and a backing plate (3) to fix a punch fixing plate (5) below the upper mold plate (1); the punch fixing plate (5) is two L-shaped plates; the two punch fixing plates (5) together fix the punch (4) on the backing plate (3); 3), the upper part of the punch (4) is T-shaped, and the upper part of the punch (4) is inserted into the space formed by the two punch fixing plates (5). The cross section of the lower part of the punch (4) has two rounded corners. The fixed die (10) is fixed to the lower template (9) by screws (14). The fixed die (10) is a symmetrical structure, and is equipped with two movable dies (11). The movable die (11) is a notched disc. The movable die (11) is embedded in the fixed die (10). The bottom of the punch (4) can be embedded in the notch on the movable die (11). The gap between the lower part of the punch (4) and the inner wall of the notch of the movable die (11) can accommodate the thickness of the steel plate.

2. The new steel plate negative angle bending die according to claim 1 is characterized in that: The upper mold plate (1), the backing plate (3) and the punch fixing plate (5) are fixed by interference fit through a pin (6).

3. The new steel plate negative angle bending die according to claim 1 is characterized in that: A spring (12) and a chuck (13) are arranged on the movable die (11); a circular hole on the chuck (13) is hooked on a convex shaft 1 on the fixed die (10); another circular hole on the chuck (13) is hooked on a central axis of the movable die (11); the convex shaft and the central axis are equidistant from the bottom surface of the lower die plate (9); one end of the spring (12) is hooked on the convex shaft 1; the other end of the spring (12) is hooked on a convex shaft 2 on the movable die (11); the convex shaft 2 is close to the circumference and the notch.

4. The new steel plate negative angle bending die according to claim 1, characterized in that: The fillet angle of the lower part of the punch (4) is greater than 20° and less than 90°.

5. The new steel plate negative angle bending die according to claim 1, characterized in that: The fillet angle of the lower part of the punch (4) is equal to 32°.

6. The new steel plate negative angle bending die according to claim 1, characterized in that: When the workpiece is bent for the second time, the ratio of R / t is less than 5, where R is the bending radius and t is the thickness of the workpiece.

7. The new steel plate negative angle bending die according to claim 1, characterized in that: When the workpiece is bent for the second time, the bending radius R is 13 mm and the bending angle is 32°.

8. The new steel plate negative angle bending die according to claim 1, characterized in that: The upper part of the fixed die (10) is stepped, the upper opening of the fixed die (10) can accommodate the lower part of the punch (4), and there is a gap between the upper part of the fixed die (10) and the lower part of the punch (4) to accommodate the thickness of the workpiece.

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