A manufacturing process for automobile beam

Abstract

The present invention provides a manufacturing process of an automobile beam, belonging to the technical field of automobile parts. A manufacturing process of an automobile beam is characterized by comprising the following steps: S1, tube rolling welding: rolling a plate into a circle and welding the two sides of the plate together to form a tube of the required diameter; S2, tube bending / pre-bending: after determining the tube to be bent or pre-bent according to finite element analysis, the tube is bent or pre-bent; S3, pre-pressing forming: forming the tube into the size range of finite element analysis; S4, hydraulic forming: placing the tube into an internal high-pressure mold for hydraulic forming, and discharging the flow medium inside the tube after forming; S5, laser cutting: placing the tube on a laser cutting tool, and laser cutting holes and edges.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile parts, in particular to a manufacturing process of an automobile beam. Background Art

[0002] In the prior art, the traditional beam process is: blanking-stretching forming / forming-punching / trimming-shaping-welding. Automobile beam products are stamping parts made of high-strength steel into the required shape. Generally, 4-8 processes are required to make the stamping parts, and then the stamping parts are welded at the buckle. The disadvantages are that the product design is limited by the weld joint position, the product shape is limited by the stamping angle (no negative angle), the product manufacturing process chain is long, and the high-strength steel rebounds and the qualified rate of the product is low. Often in the actual manufacturing process, other overlap products need to be changed according to the out-of-tolerance part of the beam. Due to the accuracy and consistency problems of the beam, the comfort of the vehicle is often reduced and the safety is also affected. Summary of the invention

[0003] The purpose of the present invention is to address the above-mentioned problems in the prior art and to propose a manufacturing process for an automobile beam, which has the characteristics of higher stability, safety, fewer process steps and high production efficiency.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A manufacturing process for an automobile beam, characterized in that it comprises the following steps:

[0006] S1. Pipe rolling and welding: roll the sheet into a circle and weld the two sides of the sheet together to form a pipe of the required diameter;

[0007] S2. Bending / pre-bending: After the pipe is determined to be bent or pre-bent according to the finite element analysis, the pipe is bent or pre-bent;

[0008] S3, pre-pressing: forming the tube into the size range of finite element analysis;

[0009] S4, hydraulic forming: put the pipe into the internal high-pressure mold for hydraulic forming, and discharge the flowing medium inside the pipe after forming;

[0010] S5. Laser cutting: Place the pipe on the laser cutting tool to perform laser cutting of holes and edges.

[0011] In the above-mentioned manufacturing process of the automobile frame, in step S1, the welding method can be straight seam resistance welding or laser welding. When straight seam resistance welding is selected, the plate needs to be rolled and welded after being cut into a preset width; when laser welding is selected, the plate needs to be rolled and welded after being cut into a preset length and a preset width.

[0012] In the above-mentioned manufacturing process of the automobile beam, in step S4,

[0013] Place the pipe into the lower die;

[0014] The two ends of the pipe are sealed and the inside of the pipe is filled with a flowing medium so that the pressure inside the pipe reaches a first preset pressure;

[0015] The upper die and the lower die are closed to compress the flowing medium inside the tube, and the pressure inside the tube reaches a second preset pressure. The inner surface of the tube is stretched under the pressure and spreads toward the inner surfaces of the upper die and the lower die;

[0016] The flowing medium inside the tube is axially compressed to reach a third preset pressure, so that the outer wall of the tube fits against the inner walls of the upper die and the lower die.

[0017] In the above-mentioned manufacturing process of the automobile beam, the flow medium is water, a low melting point alloy or wax.

[0018] In the above-mentioned manufacturing process of the automobile beam, the calculation formula of the second preset pressure is as follows: P=k(2d / D)T;

[0019] Among them, P is the internal pressure of the pipe, k is a constant coefficient with a value range of 0.6<k<1, and the value of the beam is 0.6-0.8 for high-strength steel; d is the wall thickness of the pipe, D is the diameter of the pipe, and T is the tensile strength of the pipe.

[0020] In the manufacturing process of the above-mentioned automobile beam, before the flow medium is filled into the pipe, the two ends of the pipe need to be pre-pressed. The pre-pressure formula is as follows:

[0021] F = (2d / D)YS;

[0022] Among them, F is the preload, d is the wall thickness of the pipe, D is the diameter of the pipe, Y is the yield strength of the pipe, S is the projection area of ​​the pipe end part in the Z direction, and the Z direction is the stamping direction.

[0023] In the above-mentioned manufacturing process of the automobile beam, the port of the pipe can be pre-pressed by using an oil cylinder or a nitrogen cylinder.

[0024] In the above-mentioned manufacturing process of the automobile beam, the pipe is a straight seam welded pipe with a raw material strength greater than 700MPa.

[0025] In the above-mentioned manufacturing process of the automobile beam, the thickness of the plate is ≥3mm.

[0026] In the above-mentioned manufacturing process of the automobile beam, the diameter range of the pipe is greater than 120 mm and less than 160 mm.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The present invention selects a plate for rolling and then welding. There is only one weld on the surface of the pipe, which will be simpler in process processing. In this step, there is only one weld, so the welding stress will naturally be reduced accordingly.

[0029] 2. The thickness of the plate is selected to be ≥3mm, while in traditional processes, the thickness of traditional beams is generally above 4.0mm. The cost is greatly reduced, but in the detection process, its fatigue strength, welding strength and flaring strength meet the requirements, and there is no cracking when flattened to 1 / 3 of the weld. The strength still meets the composite requirements. The overall fatigue strength of the pipe beam is much greater than that of the traditional beam, and can reach more than 100w times. After forming, the welding strength and flaring strength are not less than 18%, and there is no cracking when flattened to 1 / 3 of the weld.

[0030] 3. The internal pressure of the hydraulically formed pipe is much greater than the force of the stamping parts in the traditional process. Therefore, after the pipe is formed, the rebound of the pipe beam is small, which can make the pipe beam consistent with the pre-designed one, so the possibility of product modification in other related positions is greatly reduced.

[0031] 4. The beam produced by this process has an integrally formed hydraulic process, which has sufficient supporting strength and does not require any small supporting parts inside. The number of small supporting parts outside can be greatly reduced, so that the pipe beam can reach the required strength or exceed the required strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow diagram of the present invention;

[0033] Figure 2 It is a schematic diagram of the process of hydraulic forming in the present invention;

[0034] Figure 3 It is a schematic diagram of a beam structure in the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] in, Figure 3 Figures a and b are schematic diagrams of the beam from two perspectives.

[0037] like Figures 1 to 3As shown, a manufacturing process of an automobile beam is characterized by comprising the following steps:

[0038] S1. Pipe rolling and welding: roll the sheet into a circle and weld the two sides of the sheet together to form a pipe of the required diameter;

[0039] The plate material strength should be greater than 700MPa. When selecting the plate size, the maximum length of the plate should be 4000mm and the minimum should not be less than 500mm. The pipe made under this size can ensure its strength.

[0040] Compared with the traditional beam process, which is made of two upper and lower stamping parts spliced ​​and welded, there are two welds. The traditional stamping process generally requires 4-8 processes to make the stamping parts, and then they are buckled and welded into traditional beams; from the process chain, the number of tooling is long, and the large amount of welding is easy to cause welding deformation and welding stress. In the process of splicing two stamping parts, there will also be certain precision requirements, and the splicing efficiency will also be limited.

[0041] The present invention selects a plate for rolling and then welding. There is only one weld on the surface of the pipe, which will be simpler in process processing. In this step, there is only one weld, so the welding stress will naturally be reduced accordingly.

[0042] Furthermore, the thickness of the plate is selected to be ≥3mm, while in the traditional process, the thickness of the traditional beam is generally above 4.0mm. Its cost is greatly reduced, but during the inspection process, its fatigue strength, welding strength and flaring strength meet the requirements, and there is no cracking when flattening to 1 / 3 of the weld, and the strength still meets the requirements.

[0043] Furthermore, the pipe diameter range of the pipe is greater than 120mm and less than 160mm. The strength of the pipe beam made of the pipe in this diameter range is most suitable. In this step, the required diameter of the pipe refers to a value between the diameter range of greater than 120mm and less than 160mm, and the specific situation can be adjusted according to actual needs.

[0044] S2. Bending / pre-bending: After the pipe is determined to be bent or pre-bent according to the finite element analysis, the pipe is bent or pre-bent;

[0045] In the specific implementation process, pre-bending is to achieve wrinkle-free bending of the tube using a tube bending machine and a tube bending die, while tube bending is to achieve wrinkle-free bending of the tube using a die and a punch press.

[0046] The specific form to be adopted requires finite element analysis. However, if the pre-bending can be done conventionally, the bending can be realized, but the reverse may not be feasible;

[0047] S3, pre-pressing: forming the tube into the size range of finite element analysis;

[0048] Before setting the pipe into the mold, the pipe needs to be formed into the size range of the finite element analysis so that the pipe can be set into the predetermined mold;

[0049] Calibrate and shape the pipe in the up and down directions and left and right directions. The product design curvature must conform to the streamline design, and the turning angle should not exceed 45°.

[0050] S4, hydraulic forming: put the pipe into the internal high-pressure mold for hydraulic forming, and discharge the flowing medium inside the pipe after forming;

[0051] By placing the pipe in an internal high-pressure mold, the pipe is filled with a medium to increase the pressure and form the pipe from the inside out. The internal pressure of the pipe formed by hydraulic molding is much greater than the force of the stamping parts in the traditional process. Therefore, after the pipe is formed, the rebound of the pipe beam is small, which can make the pipe beam consistent with the pre-designed one, so the possibility of product modification in other related positions is greatly reduced;

[0052] In a specific embodiment, the R angles of the four sides of the tubular beam are designed to be no less than R15 mm.

[0053] S5, Laser cutting: Place the tube on the laser cutting tool to cut holes and edges by laser. Cutting can be done according to actual needs.

[0054] In this process, the tube beam produced in this way can greatly reduce the number of stamping parts, shorten the manufacturing process of the product, and greatly improve the production efficiency.

[0055] The traditional beam is generally composed of three sections, front, middle and rear, and each section is welded together by two stamping parts, at least 6 stamping parts in total. Since the traditional beam is welded together, it usually has small supporting parts inside and reinforcement parts outside.

[0056] The beam produced by this process has an integrally formed hydraulic process and has sufficient supporting strength. There is no need to set up small supporting parts inside, and the number of small supporting parts on the outside can be greatly reduced, so that the pipe beam can reach the required strength or exceed the required strength.

[0057] In this embodiment, the overall fatigue strength of the pipe beam is much greater than that of the traditional beam, and can reach more than 100w times. After forming, the welding strength and flaring strength are not less than 18%, and there is no cracking when the weld is flattened to 1 / 3.

[0058] In traditional technology, the thickness of traditional beams is generally above 4.0mm. This greatly reduces the cost. Not only does it greatly reduce the cost, but it can also improve the fatigue strength and production efficiency of beams more effectively than traditional beams.

[0059] Specifically, in step S4,

[0060] S41, placing the pipe into the lower die;

[0061] The pre-pressed tube is placed in the receiving groove of the lower die.

[0062] S43, sealing both ends of the pipe and filling the interior of the pipe with a flowing medium so that the pressure inside the pipe reaches a first preset pressure;

[0063] The two ends of the pipe are sealed with plugging pieces, and the inside of the pipe is filled with flowing medium. When filling, the entire inside of the pipe needs to be filled to generate a pressure of 5MPa-30MPa inside;

[0064] The flowing medium is water, low melting point alloy or wax, etc. Try to choose a medium that is fluid and almost incompressible. In the actual selection process, you can also choose materials such as hydraulic oil. When the flowing medium is processed, it will be more convenient to fill or remove the flowing medium.

[0065] By filling the interior with flowing medium, the internal stress of the product can be reduced;

[0066] S44, closing the upper die and the lower die to compress the flow medium inside the tube, so that the pressure inside the tube reaches a second preset pressure, and the inner surface of the tube is stretched under the pressure and spreads toward the inner surfaces of the upper die and the lower die;

[0067] After the upper mold is pressed down, the tube is subjected to the pressure of the upper and lower molds, thereby deforming and compressing the internal flow medium. The inner surface of the product is stretched under the pressure and spreads toward the inner surface of the mold, thereby partially fitting with the inner surface of the mold, so that the interior can reach the second preset pressure.

[0068] The calculation formula of the second preset pressure is: P=k(2d / D)T;

[0069] Among them, P is the internal pressure of the pipe, k is the constant coefficient, the value range is 0.6<k<1, and the beam is made of high-strength steel, generally the value is between 0.6-0.8 for the best effect; d is the wall thickness of the pipe, D is the diameter of the pipe, and T is the tensile strength of the pipe (the tensile strength of the original plate can be used instead for rough calculation);

[0070] S45, axially compressing the flowing medium inside the tube to reach a third preset pressure, so that the outer wall of the tube fits against the inner walls of the upper mold and the lower mold.

[0071] Axial compression refers to applying pressure to the flow medium inside the pipe in the direction of the pipe's port, thereby compressing the flow medium in the axial direction and increasing the internal pressure to a third preset pressure, so that the wall of the pipe is completely fitted to the inner walls of the upper and lower molds.

[0072] In this step, the pipe is pressed in three steps in stages so that the pipe can be better formed during the processing. The third preset pressure is sufficient to ensure that the pipe fits on the inner walls of the upper mold and the lower mold.

[0073] In the present application, the internal high pressure mold includes an upper mold, a lower mold, a press, two plugging parts, and two pre-pressing components. The upper mold and the lower mold are combined to form a channel for placing the pipe, and the press is connected to the upper mold. The two plugging parts can move and seal the two ends of the pipe, and the two pre-pressing components are arranged in the upper mold and pre-press the pipe from top to bottom. When axial pressure is applied, pressure can be applied by moving the plugging parts.

[0074] Specifically, in step S1, straight seam resistance welding or laser welding can be used for welding. When straight seam resistance welding is used, the plate needs to be cut into a preset width and then rolled and welded; when laser welding is used, the plate needs to be cut into a preset length and preset width and then rolled and welded.

[0075] In the specific welding process, it is necessary to ensure that the weld of the pipe is stable.

[0076] Specifically, S42, before the flow medium is filled inside the pipe, the two ports of the pipe need to be pre-pressurized, and the pre-pressure formula is as follows:

[0077] F = (2d / D)YS;

[0078] Among them, F is the preload, d is the wall thickness of the pipe, D is the diameter of the pipe, Y is the yield strength of the pipe (the yield strength of the original plate can be used instead for rough calculation), S is the projection area of ​​the pipe end part in the Z direction, and the Z direction is the stamping direction.

[0079] Pre-pressing the two ends of the pipe can prevent wrinkles on the pipe surface and provide the prerequisite for the pipe to be fully stretched. Only when the pipe is fully stretched can it reach the tensile strength we need. When the amount of welding is relatively large, the pipe will produce welding deformation and welding stress.

[0080] The two ports are pre-pressed in a direction perpendicular to the axis of the pipe and at the port position.

[0081] Specifically, the port of the pipe may be pre-pressed by using an oil cylinder or a nitrogen cylinder.

[0082] Specifically, the pipe is a straight seam welded pipe with a raw material strength greater than 700 MPa.

[0083] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0084] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. At the same time, the meaning of "and / or" appearing in the full text is that it includes three schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0085] The above components are all common standard parts or components known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0086] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A manufacturing process for an automobile beam, characterized in that: The following steps are involved: S1. Pipe rolling and welding: roll the sheet into a circle and weld the two sides of the sheet together to form a pipe of the required diameter; S2. Bending / pre-bending: After the pipe is determined to be bent or pre-bent according to the finite element analysis, the pipe is bent or pre-bent; S3, pre-pressing: forming the tube into the size range of finite element analysis; S4, hydraulic forming: put the pipe into the internal high-pressure mold for hydraulic forming, and discharge the flowing medium inside the pipe after forming; S5, laser cutting: place the tube on the laser cutting tool to perform laser cutting of holes and edges; In step S4, Place the pipe into the lower die; The two ends of the pipe are sealed and the inside of the pipe is filled with a flowing medium so that the pressure inside the pipe reaches a first preset pressure; The upper die and the lower die are closed to compress the flowing medium inside the tube, and the pressure inside the tube reaches a second preset pressure. The inner surface of the tube is stretched under the pressure and spreads toward the inner surfaces of the upper die and the lower die; The flow medium inside the tube is axially compressed to reach a third preset pressure, so that the outer wall of the tube fits against the inner walls of the upper die and the lower die; The calculation formula of the second preset pressure is as follows: P=k(2d / D)T; Among them, P is the internal pressure of the pipe, k is the constant coefficient, the value range is 0.6<k<1, the value of the beam is 0.6-0.8 for high-strength steel; d is the wall thickness of the pipe, D is the diameter of the pipe, and T is the tensile strength of the pipe; Before the pipe is filled with flowing medium, the two ports of the pipe need to be pre-pressurized. The pre-pressure formula is as follows: F = (2d / D)YS; Among them, F is the preload, d is the wall thickness of the pipe, D is the diameter of the pipe, Y is the yield strength of the pipe, S is the projection area of ​​the pipe end part in the Z direction, and the Z direction is the stamping direction.

2. The manufacturing process of the automobile beam according to claim 1, characterized in that: In step S1, the welding method can be straight seam resistance welding or laser welding. When straight seam resistance welding is selected, the plate needs to be cut into a preset width and then rolled and welded; when laser welding is selected, the plate needs to be cut into a preset length and preset width and then rolled and welded.

3. The manufacturing process of the automobile beam according to claim 1, characterized in that: The port pre-pressing of the pipe can be done by using an oil cylinder or a nitrogen cylinder.

4. The manufacturing process of the automobile beam according to claim 1, characterized in that: The pipe is a straight seam welded pipe with a raw material strength greater than 700MPa.

5. The manufacturing process of the automobile beam according to claim 1, characterized in that: The thickness of the plate is ≥3mm.

6. The manufacturing process of the automobile beam according to claim 1, characterized in that: The pipe diameter range is greater than 120 mm and less than 160 mm.

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