Verification method for blank holder force of double-groove die

Abstract

The invention provides a verification method for the blank holder force of a double-groove die, and belongs to the field of automobile part manufacturing processes, and the verification method comprises the following steps: S1, arranging a connecting belt for connecting different workpieces between the different workpieces, and eliminating the limitation that one material is required during simulation; s2, workpiece gas caps on the left side and the right side are arranged in a balanced mode, so that the blank holder force distributed to each workpiece is the blank holder force needed by workpiece drawing; s3, according to the actual die state, female dies, blank holders and male dies of the left workpiece and the right workpiece are independently presented, connection treatment is not conducted, the working strokes of the left workpiece and the right workpiece are set to be consistent, and simulation is conducted; and S4, judging a simulation result, judging that the simulation result is qualified if the stress of the gas cap is balanced, the main strain and the thinning rate of the outer plate conform to set parameters and the inner plate is not cracked, and if the simulation result is not qualified, readjusting the layout of the gas cap until the simulation result is judged to be qualified. The forming production frequency of different materials, different material thicknesses and different workpieces is reduced, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the field of automobile parts manufacturing technology, relates to parameter simulation analysis verification in a parts drawing process, and in particular to a verification method for the blank holding force of a double-groove die. Background Art

[0002] In recent years, the domestic automobile industry has developed rapidly and the competition has become increasingly fierce. Major automobile companies have not only increased their investment in styling and performance to attract consumers, but also tried every means to reduce internal development costs. In addition to improving material utilization and reducing the number of mold sets under normal circumstances, it is also necessary to consider reducing the production cost of stamping equipment. If the equipment conditions allow, double slots and multiple stations can be used to reduce production costs, thereby reducing the cost of the entire vehicle.

[0003] Whether it is double slots, triple slots, or multiple slots, the purpose of reducing the cost of the whole vehicle is to reduce the frequency of production. Double slots or multiple slots are for the same model, because the demand for the same model is the same, and the quantity of demand is the same. For example, if model A is expected to produce 1 million vehicles, then both parts on vehicle A will require 1 million vehicles. If they are matched with similar parts of other similar vehicles into a multi-slot structure, the process is simplified. Due to the difference in the final production volume of different vehicles, one-mold processing of one of the parts will result in waste of output, or empty slot processing. Therefore, double-sided slots or multi-sided slots are for different parts of the same vehicle, so as to ensure maximum utilization and reduce costs. For double slots or triple slots, there is no requirement for the similarity of parts. They can be similar or completely different. There is no limitation. All is fine. This is the key to reducing costs.

[0004] At present, double-slot production for left and right parts with the same material has been widely used, while the matching of blank holding force for double-slot production of asymmetric parts has always been a difficult problem that has plagued the improvement of production efficiency. Different parts require different pressures. When the pressure difference is large enough, the parts with higher pressure will be produced, and the parts with lower pressure may be torn. If the pressure is relatively large, the pressure value of the stamping machine may be insufficient. Due to the existence of the pressure difference problem, the production of double-slot or multi-slot molds for different parts has always been an insurmountable problem. Moreover, in all stamping simulation software, only simulation verification of single material can be performed, and verification of double molds and double materials cannot be performed according to actual conditions. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a verification method for the clamping force of a double-slot mold. A solution is proposed for the situation in the background technology that double-slot or multi-slot processing cannot be performed due to excessive pressure. Through the verification method of this application, actual production is simulated. After verification, the simulated plan is used to guide the layout of the gas cap in actual production, thereby realizing the combination of simulation and practice, meeting the double-slot production or multi-slot production of different parts when the pressure difference is too large, reducing the frequency of parts production, greatly reducing production costs, and saving costs by at least 37%.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a verification method for the blank holding force of a double-groove mold is suitable for verifying the blank holding force in the forming work of different materials, different material thicknesses and different parts. The simulation verification process includes the following steps: S1. A connecting belt is set between different parts to connect the two parts, so that different parts can eliminate the limitation of having to use one piece of material during simulation; S2. Balance the air caps on the left and right sides of the workpieces. The air caps are used to provide the blank holding force during the forming of the workpieces. The variable blank holding control is achieved through the blank holding ring so that the blank holding force allocated to each workpiece is the blank holding force required for the drawing of the workpiece. S3. According to the actual mold state, the concave mold, blank holder and punch of the left and right parts are presented separately without connection. The working stroke of the left and right parts is set to be the same for simulation; S4. Determine the simulation results and confirm that the force on each gas cap of the blank holder is balanced, the principal strain and the thinning rate of the outer plate meet the set parameters, and the inner plate does not crack. The simulation result is qualified. If it is unqualified, readjust the layout of the gas caps until the simulation result is determined to be qualified.

[0007] Furthermore, in step S1, the connecting strip is arranged in an area where the material flow is relatively small and the blank holder is relatively flat during the drawing process of the workpiece, so that there is no flow at this position during the forming process of the workpiece.

[0008] Furthermore, in step S1, the connecting belt is suspended in the air, and its free gravity state does not affect the gravity state of the workpiece itself, and the smaller the specification, the better.

[0009] Furthermore, the connecting belt includes a first extension belt connected to the left-side component, and also includes a second extension belt connected to the right-side component. The first extension belt and the second extension belt are configured in the software as an integral structure connected in a welding manner to form a welding seam.

[0010] Furthermore, the welding seam is located in the middle of the length direction of the connecting belt, and the connecting belt can be set to be connected in a straight line state, or can be set to be connected in an arc state with one end higher than the other end.

[0011] Furthermore, the width H of the connection belt is 3-5 mm, and the fillet R of the connection between the connection belt and the left and right parts is 10-20 times the thickness of the thicker part among the left and right parts.

[0012] Furthermore, when the thickness of the product is less than 0.8 mm, the width of the connecting belt is 3 mm; when the thickness of the product is greater than 0.8 and less than 1.5, the width of the connecting belt is 5 mm.

[0013] Furthermore, in step S2, each gas cap is given a maximum load limit, the maximum load of each gas cap does not exceed 5T, the number of gas caps in the quadrant corresponding to each workpiece is balanced, and the gas cap layout is set according to the required clamping force of the workpiece. It can be set outside the workpiece range so that the pressure value allocated to the workpiece is consistent with the pressure value required for drawing the workpiece.

[0014] Furthermore, in step S4, the principal strain is greater than 5%, and the outer plate thinning rate is between 5% and 20%, and the simulation result is qualified.

[0015] Furthermore, the method further includes step S5, in which, according to the qualified situation verified in step S4, the layout of the gas cap in the actual production of the mold is set.

[0016] Compared with the prior art, the present invention has the following advantages and positive effects.

[0017] 1. The present invention is based on the simulation of Auto Form software. By setting connecting belts on different parts, the limitation that only one piece of material must be used in the simulation in the software is broken, so that the simulation of different parts becomes possible. Secondly, through the balanced layout of the gas cap, the pressure on both sides is guaranteed to be the same and the pressure value of the side with larger pressure is satisfied. On this basis, the variable pressure edge control is realized through the blank holder ring, so that the blank holder force allocated to the other part is the blank holder force required for the drawing of the part. Then, the simulation is performed in the software until the principal strain and the thinning rate of the outer plate meet the set parameters, the inner plate does not crack, and the simulation result is qualified. Then, according to the gas cap layout under the qualified simulation state, the gas cap layout of the actual mold production is set, and the double-groove or multi-groove processing of different materials, different material thicknesses and different parts is realized. Such a verification method is used for the actual manufacturing of the mold, and the situation that different parts can be processed with multiple grooves in the same mold when the pressure difference is large is realized, which solves the situation that single-mold production is required, and the production frequency is greatly reduced. The processing cost of double groove is reduced by at least 37% lower than that of single groove, and the proportion of cost reduction of multi-groove processing is greater; 2. The setting of the connection belt is ingenious. The setting position is located in the area where the material flow is relatively small and the blank holder is relatively flat, so that there is no flow at this position during the molding process of the part. Therefore, the connection belt is set in the simulation state, breaking through the software display, and does not exist in actual production. Therefore, there is no flow at this position in actual production, ensuring that whether it is connected in actual production does not affect the overall quality. It not only ensures the setting in the software, but also achieves matching with the actual situation. If the connection belt is placed in an area with large flow, there will be a risk of the connection belt affecting the inflow in the simulation, and there is a risk of inaccurate verification of the actual production of the part; 3. In this application, a precise parameter range is set for the connecting belt. For example, the position of the welding seam is set in the middle. The purpose is to consider that the positions of the left and right parts of the welding seam are relatively farthest, so as to avoid the influence of the elongation difference of the connecting belt on the forming state of the part due to the difference in material properties and material thickness in the forming simulation. At the same time, the width and R angle of the connecting belt are set. The width range avoids flow, and the setting of the R angle avoids stress concentration and tearing. The overall setting ensures the stability of the connecting belt during the simulation process and improves the accuracy and efficiency of the qualified simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 This is a schematic structural diagram of double-slot production of workpieces of different materials, different shapes, and different material thicknesses in Example 1 of the present invention; Figure 2-1 This is a state diagram of the outer panel of the hood extending under the condition of the blank holding force of 120T in Example 1 of the present invention; Figure 2-2 1 is a state diagram of the outer panel of the hood extending under the condition of the blank holding force of 180T in Example 1 of the present invention; Figure 3-1 1 is a state diagram of the inner panel of the hood extending under the condition of the blank holding force of 120T in Example 1 of the present invention; Figure 3-2 1 is a state diagram of the inner panel of the hood extending under the condition of the blank holding force of 180T in Example 1 of the present invention; Figure 4 This is a state diagram of the hood inner panel and the hood outer panel after the connecting belt is provided in Embodiment 1 of the present invention; Figure 5 is a schematic diagram of the connecting belt of the present invention being connected in a curved shape; Figure 6 This is one of the embodiments of the top view of the connecting belt in the connected state of the present invention; Figure 7 is a schematic plan view of the arrangement of the gas cap in Example 1 of the present invention; Figure 8 It is a schematic diagram of the positional relationship between various parts during the actual process of the mold of the present invention; Fig. 9 is a schematic diagram of simulation verification results of stiffness and strain values ​​reaching the standard in Example 1 of the present invention; Fig.10 It is a schematic diagram of the simulation verification results of the plastic thinning rate reaching the standard in Example 1 of the present invention.

[0020] Reference numerals: 1-connecting belt; 11. first extension belt; 12. second extension belt; 2. concave die; 3. pressure ring; 4. punch; 5. air cap. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0024] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] Due to the limitations of the Auto Form software, the process verification of the blank holding force and forming force of a conventional double-slot die needs to be verified and analyzed separately. That is, for a piece of material, the side with a larger blank holding force is used as the reference, and the state of the workpiece on this side is ensured to be stable and reliable, and the workpiece on the other side is re-corrected by drawing.

[0026] Thinning rate of stamping parts: It is the percentage of thickness reduction of the sheet during the stamping process. Thinning rate = (S0-S) / S0x100%, where S0 is the theoretical wall thickness of the part before stamping, and S is the actual wall thickness of the final formed part. The main reason for the thinning phenomenon during the stamping process is the extrusion effect of the punch and die, which makes the sheet affected by tensile force and tangential stress. At the same time, the friction generated when the material is deformed will also aggravate the thinning phenomenon. Too small thinning rate will reduce the deformation accuracy, increase the complexity of the mold and increase the cost. Too large thinning rate may cause problems such as part deformation, reduced hardness, reduced strength and even cracking, which will seriously affect the service life and safety of the product.

[0027] Drawing, also known as deep drawing, stretching, calendering, etc., refers to the method of using a mold to deform the sheet through cold working, so that the sheet is gradually elongated and becomes the desired shape.

[0028] Blank holding ring: It is a clamping device mainly designed to prevent the stamping and drawing products from wrinkling during the deep drawing process. In the deep drawing process, it prevents the edge of the workpiece from becoming unstable and wrinkling. A blank holding ring is set at the edge between the concave and convex dies. The blank holding ring is used to achieve variable blank holding control and reduce costs. Working principle: The hydraulic cylinder provides a constant pressure through the ejector rod. Because the small ejector column has a series of length changes, when the small ejector column transmits force to the upper layer, different areas of the upper layer will produce different elastic deformations, thereby producing different blank holding forces in different areas of the upper layer, achieving the purpose of partitioned blank holding. Replacing the blank holding ring can achieve partitioned variable blank holding force control and reduce production costs.

[0029] Binder force: It is based on the minimum lifting force required to overcome the drawbead forming during the closing process of the forming upper die and the binder ring. It is adjusted and set on the premise of controlling the material flow state, making the sheet have sufficient tension, and optimizing the material utilization rate, and meeting the principle of stable production of parts with high precision.

[0030] Drawbead: A convex rib structure, generally set on the blank holder, and a corresponding rib groove is opened on the surface of the die, i.e., a concave rib. The convex rib can also be set on the surface of the die, and the concave rib can be set on the blank holder. The functions of the drawbead are as follows: 1. Strengthen the control ability of the press face on the material flow; 2. Increase the feeding resistance, so that the blank can withstand sufficient tensile stress, improve the rigidity of the drawn part and reduce the surface defects caused by springback; 3. Expand the adjustment range of the blank holder force. The blank holder force and the drawbead complement each other. The same purpose can be achieved by reducing the blank holder force by adjusting the resistance of the drawbead; if the constraint force of the drawbead is too small, it is easy to wrinkle; if the constraint force of the drawbead is too large, it is easy to tear.

[0031] The principal stress is the largest stress among all the different directions in an object. When an object is subjected to stress in multiple directions, multiple stress values ​​will be generated, and the largest one is called the principal stress. The principal stress may be tensile stress or compressive stress.

[0032] The principal strain refers to the largest strain among all the strains in different directions in an object. Strain is a quantity used in mechanics to measure the degree of deformation of an object. When an object is subjected to stress, different strains may be generated in different directions. The largest one is called the principal strain.

[0033] ‌Gas cap: refers to a device used in the drawing die to provide blanking force for part forming. The gas cap is mainly used to provide blanking force during part forming to ensure that the material can be stably maintained in the mold during the stretching process. Gas caps are usually arranged around the contour line of the punch, approximately one every 300mm, and the load of a single gas cap is generally between 3-5 tons. The number of gas caps is calculated based on the blanking force. The specific number is the blanking force divided by the load of a single gas cap plus a certain safety number. The gas caps should be distributed as evenly as possible on the outside of the parting line and close to the parting line to ensure force balance. Secondly, the length of the gas cap rod should be less than the height of the work surface, and the gas cap rod should not be higher than the work surface when working.

[0034] like Figure 1-10 As shown, the present invention is a verification method for the blank holding force of a double-groove mold, which is suitable for verifying the blank holding force in the molding work of different materials, different material thicknesses and different workpieces. The simulation verification process includes the following steps: S1. Connecting belts are set between different parts to eliminate the limitation that different parts must have one piece of material during simulation. Because they are connected during simulation, no connecting belt is set during actual production. Simulation needs to be consistent with reality. Therefore, the setting of this connecting belt needs to break the routine. When simulating in the software, the position setting is used to eliminate the software limitation but not actually generate flow to ensure consistency with reality. This idea is ingenious and not well known. It needs to break the conventional cognition and reverse thinking to ensure that the actual force and flow of parts are consistent under the premise that the theoretical simulation is inconsistent with the actual structure. S2. Balance the air caps on the left and right sides of the workpieces to solve the problem that the blank holding forces of the left and right parts must be unified. The air cap is used to provide the blank holding force during the forming of the workpiece. The variable blank holding control is achieved through the blank holding ring so that the blank holding force allocated to each workpiece is the blank holding force required for the drawing of the workpiece. The air cap on the side with smaller required pressure can be set on the periphery of the manufacturing area; S3. According to the actual mold state, the left and right parts of the concave mold, the blank holder and the punch are presented separately without connection processing, such as Fig. 9 As shown, the working strokes of the left and right parts are set to be the same, and the simulation is carried out. Through the balanced setting of the gas cap, the total pressure on both sides is the same, so the working strokes of the left and right parts are the same. It is just that through variable pressure control, under the premise of ensuring the consistency of the total pressure, the force allocated to each part is different; S4. Determine the simulation results and confirm that each gas cap of the blank holder is balanced in force, the principal strain and the outer plate thinning rate meet the set parameters, and the inner plate does not crack. The simulation result is qualified. If it is unqualified, readjust the layout of the gas caps until the simulation result is qualified. This realizes the guidance of theory to practice, achieves the actual production of double-groove or multi-groove processing, and reduces the frequency.

[0035] Preferably, in step S1, the connecting belt is arranged in an area where material flow is relatively small and the blank holder is relatively flat during the drawing process of the workpiece, so that there is no flow at this position during the forming process of the workpiece, thereby ensuring that the theory can be simulated and there is no actual flow, which is consistent with the actual forming state.

[0036] Preferably, in step S1, the connecting belt is suspended in the air, and its free gravity state does not affect the gravity state of the workpiece itself. The smaller the specification, the better. During the simulation verification process, the connecting belt is in a free state and is not restricted by other tool bodies. The simulation is a non-interference situation in the software. There is no connecting belt in reality, so there is no interference problem.

[0037] Preferably, the connecting belt includes a first extension belt connected to the left-side workpiece, and also includes a second extension belt connected to the right-side workpiece. The first extension belt and the second extension belt are set in the software as an integral structure connected in a welding manner to form a welding seam. When the two workpieces are actually connected, the sheet metal parts are welded, so they are set to a welding manner during simulation, which is consistent with the actual situation.

[0038] Preferably, the welding seam is located in the middle of the length direction of the connecting belt, and the welding seam is located in the middle of the connecting belt of the left workpiece and the right workpiece. This is to consider that the position of the welding seam is relatively farthest from the left workpiece and the right workpiece, so as to avoid the influence of the connecting belt extension difference on the forming state of the workpiece due to the difference in material properties and material thickness in the forming simulation. The connecting belt can be set to be connected in a straight line state, such as Figure 4 As shown, it can also be set to an arc state connection with one end high and the other end low, such as Figure 5 The schematic diagram is determined according to the actual situation of the workpiece to ensure that the position where there is no flow is the best.

[0039] Preferably, the width H of the connecting band is 3-5mm, and the radius R of the connection between the connecting band and the left and right parts is 10-20 times the thickness of the thicker part among the left and right parts. More preferably, the thickness of the part is less than 0.8mm, and the width of the connecting band is 3mm; the thickness of the part is greater than 0.8 and less than 1.5, and the value is 5mm. For example, if the material thickness is 0.7, R is R7. The smaller the specification of the connecting band is, the better without affecting the flow of the material, but it cannot be too small. If it is too small, it will break due to the existence of gravity and will not play the role of connection. The R angle is to avoid stress concentration and tearing.

[0040] Preferably, in step S2, each gas cap is given a maximum load limit, the maximum load of each gas cap does not exceed 5T, and the number of gas caps in the quadrant corresponding to each workpiece is balanced, such as Figure 7 As shown, the air cap layout is set according to the blank holding force required by the workpiece, and can be set outside the workpiece range so that the pressure value distributed to the workpiece is consistent with the pressure value required for drawing the workpiece.

[0041] Preferably, in step S4, the principal strain is greater than 5%, the outer plate thinning rate is between 5% and 20%, and the simulation result is qualified. This parameter ensures sufficient ductility and rigidity of the workpiece.

[0042] Preferably, step S5 is also included, and according to the qualified situation verified in step S4, the layout of the gas cap is set in the actual production of the mold. This is the key to guiding practice by theory. Under the premise of achieving overall force balance on both sides through the layout of the gas cap, the force on the parts is the pressure required by each part, and the variable pressure edge control under the same total pressure is completed, which meets the double-slot or multi-slot production between different parts and solves the problem of double-slot or multi-slot production being unable to be carried out due to excessive pressure difference.

[0043] Example 1: The left part in the figure is the inner plate of the hood, with a thickness of 0.7mm and made of ordinary stamped carbon steel DC04; the right part is the outer plate of the hood, with a thickness of 0.8mm and made of high-strength bake-hardened steel HC180P1. In these two parts, the yield strength of the outer plate of the hood is greater than that of the inner plate of the hood. The outer edge of the hood usually uses locking ribs, and the lifting force required for its molding is much greater than the inner side flow ribs.

[0044] like Figure 2-1 As shown in the figure, the right part is the hood outer panel. When the blanking force is 120T, the material cannot be fully extended during the forming process, and the thinning rate is less than 5%, which cannot meet the stiffness requirements of the workpiece itself. This state will cause resonance during the actual loading and driving process, and fatigue damage will occur over time. The left hood inner panel has no problem in forming when the blanking force is 120T, as shown in the figure. Figure 3-1 as shown; Figure 2-2 As shown in the figure, when the blanking force of the hood outer panel is 180T, the software simulation shows that there is no stress concentration problem, the material is fully extended, and the stiffness of the part meets the standard. However, when the blanking force is 180T, the inner panel of the hood on the left side is severely cracked, and the surrounding and middle bright parts are the cracked areas, as shown in the figure. Figure 3-2 As shown, in actual production, whether double-groove or multi-groove production is possible depends on the characteristics of the parts. The pressure difference cannot exceed 25% of the minimum pressure. In this embodiment, (180-130) / 130>25%, which exceeds the pressure difference value that can be produced with double grooves in the prior art. The two parts cannot be processed with double grooves and are mostly produced using a single independent mold.

[0045] The stiffness extension of the material refers to the material reaching a sufficient elongation rate, that is, the elongation of the material overcomes the yield strength and elastic deformation of the material itself. The thinning rate of the hood outer panel is above 5%, the principal strain reaches above 3% or 4%, and the secondary strain reaches above 0. The principal strain and secondary strain are balanced, which is the best state. For example, the principal strain is 3% and the secondary strain is 3%. This is the best state of extension. This parameter can ensure the stability of the parts after extension, and the above problems are not easy to occur.

[0046] The resonance that occurs during the actual loading and driving process refers to the fact that during the vibration of the engine, due to insufficient extension, the parts are unstable and undergo micro-deformation, which vibrates together with the engine, forming resonance. During the vibration process, the welding points of the workpiece are damaged or fall off, causing serious safety hazards. This is not allowed and must be overcome in the industry.

[0047] Existing solution: The required blanking force for the outer panel of the hood is greater than that for the inner panel of the hood. The blanking force calculated for the outer panel of the hood is used as the basis, and then the inner panel of the hood is corrected. Figure 3-2The cracking problem caused by the increased clamping force requires a lot of time and effort to adjust the solution and verify it. The same risk will also be directly transmitted to the later production and manufacturing links.

[0048] The premise of the existing solution: the blanking force that the customer's production equipment can provide meets the sum of the blanking forces of the two pieces. In the use requirements of conventional production equipment, the equipment working force that can be used in the design cannot exceed 80% of the maximum force that the equipment can provide. For example, the inner and outer panels of the engine cover mentioned in this article require a blanking force of 180+180=360T, and the maximum blanking force that the production equipment can provide should be no less than 450T, that is, 450T*80%=360T.

[0049] If the blanking force of the equipment provided by the customer cannot meet the design requirements, the following two technical means are usually used: Technical means 1: Develop molds for two parts separately, and double the number of mold sets. This results in an equal increase in costs for both parties. Party A's project development costs increase by 35%, later production costs such as labor costs and equipment energy consumption costs increase by 50%, and the customer's factory inventory space is reduced. Party B's production unit has an increase of 50% in technical R&D personnel, and later production processing, debugging and machine verification costs increase by 40%.

[0050] Technical means 2: Correct the insufficient clamping force of the equipment by adding an external force source to meet the design requirements, such as adding a nitrogen spring. Taking the addition of a 50-ton force source as an example, the manufacturing cost of the problematic project caused by the addition of a nitrogen spring increases by about 10%; the frequency of mold maintenance increases by 100%; and the balance correction of the customer's production equipment increases by 50%.

[0051] The above existing solutions seem to reduce costs to a certain extent, but they make research and development difficult, greatly increase the initial research and development costs, increase mold costs, increase the initial debugging and daily maintenance costs of personnel, and increase the subsequent after-sales costs accordingly. It is feasible in theory, but difficult to implement in practice.

[0052] In the verification method of this application, in the embodiment, two connecting belts are set, which is determined according to the actual situation of the workpiece, and at least one is set. Strictly follow the steps of this application to perform verification simulation. After the simulation is qualified, guide the actual mold production and gas cap layout. Figure 7 It is a schematic diagram of the positional relationship between the various parts. The actual mold working process is as follows.

[0053] (1) When the mold tool body is open, the blank holders are lifted synchronously by the air cap, and both blank holders are lifted completely; (2) The workpiece is placed in the blank holder, and the respective positioning devices are used to accurately control the workpiece in the respective working area. In the simulation software, the connecting belt is in a suspended state, there is no interference problem, and no flow occurs. In actual production, the connecting belt does not exist, so there is no interference; (3) The upper die tool body moves downward, and the air cap provides pressure to the blank holder to ensure that the draw ribs are fully formed; (4) The upper die tool body continues to apply pressure to overcome the blank holder force provided by the lower air cushion. The upper die tool body and the blank holder ring tool body move downward synchronously and contact the lower die tool body to form the material. The drawing work is completed to the end and the blank holder force is checked. The maximum value during the working process is 224.7T, which meets the 240T requirement given by the design.

[0054] After all the work is completed, check whether it is consistent with the simulation results, whether the stress on each push rod of the blank holder is balanced, whether the air cap is balanced, the principal strain reaches more than 5%, the thinning rate of the outer plate reaches 5%-20%, and the inner plate does not crack. This represents consistency with the simulation state, achieving the verification of simulation guiding production and the consistency between theory and production.

[0055] This application makes up for the defects of industry simulation software by changing the process thinking, and solves the verification of the double-groove production clamping force and working forming force of different parts, different material thicknesses and different materials, so that the feasibility of the double groove can be accurately judged during the early design period, giving customers accurate information, which can save development costs and production costs for customers, and save design costs and manufacturing costs for themselves. The technical solution of this application can be used for double-groove processing and multi-groove processing verification. For double-groove processing, the cost is reduced by up to 37%. The double-groove processing mold is relatively complex compared to the single-groove, but the mold accounts for 2%-5% of the production and manufacturing cost of the entire part drawing process. The proportion is relatively low, and the production frequency accounts for a higher proportion of the entire drawing cost. The cost of changing from a single-slot to a double-slot mold increases, and the subsequent maintenance costs increase. However, with double-slot production, the production frequency of two pieces is reduced by 50%. The overall cost reduction can reach 37%. Under the current technical level where the mold cost has been suppressed to a very low level, even a 1% reduction in cost is considerable. The technical solution of this application has brought obvious economic benefits of cost reduction, and it has broken through the pressure difference limitation and technical barriers, and has a huge impact on the industry. This patent is applied in the special project of innovative application scenarios of major science and technology support plans of Hebei Province, project number 242Q1803Z, as a subsequent application promotion project.

[0056] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. The verification method of the blank holding force of the double-groove mold is suitable for the verification of the blank holding force in the forming work of different materials, different material thicknesses and different parts. It is characterized by: The simulation verification process includes the following steps: S1. A connecting belt is set between different parts to connect the two parts, so that different parts can eliminate the limitation of having to use one piece of material during simulation; S2. Balance the air caps on the left and right sides of the workpieces. The air caps are used to provide the blank holding force during the forming of the workpieces. The variable blank holding control is achieved through the blank holding ring so that the blank holding force allocated to each workpiece is the blank holding force required for the drawing of the workpiece. S3. According to the actual mold state, the concave mold, blank holder and punch of the left and right parts are presented separately without connection. The working stroke of the left and right parts is set to be the same for simulation; S4. Determine the simulation results and confirm that the force on each gas cap of the blank holder is balanced, the principal strain and the thinning rate of the outer plate meet the set parameters, and the inner plate does not crack. The simulation result is qualified. If it is unqualified, readjust the layout of the gas caps until the simulation result is determined to be qualified.

2. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: In step S1, the connecting strip is arranged in an area where material flow is relatively small and the blank holder is relatively flat during the drawing process of the workpiece, so that there is no flow at this position during the forming process of the workpiece.

3. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: In step S1, the connecting belt is suspended in the air, and its free gravity state does not affect the gravity state of the workpiece itself, and the smaller the specification, the better.

4. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: The connecting belt includes a first extension belt connected to the left-side component, and also includes a second extension belt connected to the right-side component. The first extension belt and the second extension belt are set in the software as an integrated structure connected in a welding manner to form a welding seam.

5. The method for verifying the blank holding force of a double groove die according to claim 4, characterized in that: The welding seam is located in the middle of the length direction of the connecting belt. The connecting belt can be connected in a straight line state or in an arc state with one end higher than the other.

6. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: The width H of the connecting belt is 3-5 mm, and the fillet R of the connection between the connecting belt and the left and right parts is 10-20 times the thickness of the thicker part among the left and right parts.

7. The method for verifying the blank holding force of a double groove die according to claim 6, characterized in that: If the thickness of the product is less than 0.8mm, the width of the connecting belt is 3mm; if the thickness of the product is greater than 0.8 and less than 1.5, the width of the connecting belt is 5mm.

8. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: In step S2, each gas cap is given a maximum load limit, and the maximum load of each gas cap does not exceed 5T. The number of gas caps in the quadrant corresponding to each workpiece is balanced. The gas cap layout is set according to the required clamping force of the workpiece, and can be set outside the workpiece range so that the pressure value allocated to the workpiece is consistent with the pressure value required for drawing the workpiece.

9. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: In step S4, the principal strain is greater than 5%, and the outer plate thinning rate is between 5% and 20%, and the simulation result is qualified.

10. The method for verifying the blank holding force of a double groove die according to claim 1, characterized in that: The method further includes step S5, in which, according to the qualified situation verified in step S4, the layout of the gas cap in the actual production of the mold is set.

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