A hydraulic forming apparatus and method for pipe fittings with flanges

Abstract

This invention discloses a hydraulic forming apparatus and method for flanged pipe fittings, including a pipe, a worktable, and a forming device. The forming device is fixedly installed on the worktable. After the forming device closes the mold, it forms a groove with a flange. The pipe is placed in the groove and processed to form the flange. An inner mold of the forming device is provided inside the pipe. This process produces integral hollow components with flanges with simple procedures, reducing production costs and improving production efficiency. During the forming process, the workpiece weight remains unchanged. Through reasonable structural design, the workpiece weight obtained using this invention is lower than that of stamped and welded workpieces. This invention can directly form single-sided assembly flanges, thereby improving material utilization and reducing material waste.

Description

Technical Field

[0001] This invention relates to the field of internal high-pressure forming technology, and in particular to a hydraulic forming apparatus and method for pipe fittings with flange edges. Background Technology

[0002] According to statistics, the number of vehicles in China reached 302 million in 2021. Due to the sheer number of vehicles, vehicle emissions have become a major source of pollution. Currently, the world advocates for "low-carbon, environmentally friendly, energy-saving, and emission-reducing" practices. Against this backdrop, reducing vehicle emissions is imperative, hence the concept of vehicle lightweighting. Vehicle lightweighting reduces vehicle emissions by lowering the vehicle's weight. For every 100kg reduction in vehicle weight, fuel consumption can be saved by 0.3L–0.5L / (100km), and CO2 emissions can be reduced by 8g–11g / (100km). Vehicle lightweighting can be divided into material lightweighting and structural lightweighting. Material lightweighting involves using lightweight materials such as aluminum, magnesium, high-strength steel, and carbon fiber. Using integral hollow structural components instead of solid structural components is an important approach to vehicle structural lightweighting. Internal high-pressure forming technology is the main technology for forming integral hollow structural components. The forming principle of internal high-pressure forming technology is as follows: a tube blank is placed between upper and lower molds, and both ends of the tube blank are sealed using a sealing punch. High-pressure liquid is injected into the tube blank, and the high-pressure liquid serves as a force transmission medium to form the tube blank within the mold cavity. The advantages of internal high-pressure forming technology are: the entire forming process usually requires only one set of molds, resulting in lower production costs; the formed part is integrally formed, with good mechanical properties and high material utilization.

[0003] In current automotive assembly processes, the assembly of integral hollow components mainly relies on flanges. Currently, the forming process for flanges is primarily stamping and welding: each part is first stamped, and then the stamped parts are welded together. Compared to internal high-pressure forming technology, stamping and welding has the following drawbacks: 1. Stamping and welding often requires multiple processes, resulting in a larger production line layout area, longer production cycle time, and higher manufacturing costs; 2. Due to the splicing nature of stamping and welding, the mechanical properties of the formed workpiece are lower than those of integral forming; 3. Since stamping and welding involves welding two stamped plates together, the formed workpiece usually requires assembly flanges on both sides. However, when assembling this workpiece with other parts, only one flange needs to be connected, which reduces material utilization, increases vehicle weight, and does not improve the workpiece's mechanical properties. Furthermore, internal high-pressure forming, due to its expansion and deformation characteristics, is difficult to form hollow integral structural parts with flanges. Therefore, a new hydroforming technology is needed to form integral hollow structural parts with flanges. Summary of the Invention

[0004] The purpose of this invention is to provide a hydraulic forming apparatus and method for pipe fittings with flanges, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides a hydraulic forming apparatus for pipe fittings with flanges, characterized in that it includes: a pipe, a worktable, and a forming device;

[0006] The forming device is fixedly installed on the workbench. After the forming device closes the mold, it forms a groove with a flange edge. The pipe is placed in the groove and processed to form a flange edge. The inner mold of the forming device is provided inside the pipe.

[0007] The forming device also includes a high-pressure source, an upper mold, a lower mold, a sealing punch, and a press; the upper mold is driven and mounted on the bottom surface of the press, and the press is used to provide the mold closing force during mold closing;

[0008] The lower mold is fixedly installed on the worktable;

[0009] The inner mold is tightly fitted to a sealing punch at each end; the two ends of the pipe are respectively sealed and connected to the two sealing punches; the high-pressure source is connected to the inner cavity of the pipe.

[0010] The high-pressure source is used to generate outward expansion pressure inside the pipe.

[0011] The sealing punch is sealed to the pipe via an O-ring; the sealing punch is also connected to the sealing cylinder via a transmission mechanism.

[0012] It is also equipped with a control system; the control system controls the lifting and lowering of the upper mold through the press, and then forms the flange edge through the forming guide of the inner mold and the closing of the upper mold; the control system controls the feeding of the sealing punch through the sealing cylinder; the control system controls the pressure supply of the high pressure source.

[0013] A shaping pressure plate and / or a pad are also provided between the pipe and the upper mold; the shaping pressure plate and the pad are used to control the formation of the top of the pipe and the forming of the flange edge, respectively.

[0014] A hydroforming method for pipe fittings with flange edges includes the following steps:

[0015] S1 equipment is debugged, and the pipe is placed on the lower mold;

[0016] S2 places the inner mold inside the pipe and uses a sealing punch to axially seal the pipe, ensuring no pressure leakage and simultaneously assembling and positioning the inner mold.

[0017] S3 controls the high-pressure source to inject low-pressure liquid into the pipe through the control system;

[0018] S4 controls the high-pressure source through the control system to generate high-pressure liquid, which provides support in the inner cavity of the pipe; the pressure in the inner cavity of the pipe is constant; and the upper mold is driven by the press to descend and close with the lower mold, which, together with the inner mold, forms the initial shape of the flange edge structure;

[0019] S5 uses the control system to control the press to return to its original position, the sealing punch to its original position, and the high-pressure source to stop generating high-pressure liquid, and removes the inner mold; place a pad and a shaping plate on the initially formed flange edge, and use the control system to control the press to descend until the flange edge is formed;

[0020] S6 completes mold closing, resets all equipment, and removes the pipe.

[0021] The present invention discloses the following technical effects: the integral hollow component with flange edge produced by this process is simple to manufacture, reduces the economic cost of production and improves production efficiency; the weight of the workpiece does not change during the forming process of this process, and through reasonable structural design, the weight of the workpiece obtained by using the present invention is lower than that of stamped and welded workpieces; using the present invention, a single-sided assembly flange can be directly formed, thereby improving material utilization and reducing material waste. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram showing the positional relationship between the forming device and the tube blank before the experiment;

[0024] Figure 2 This is a schematic diagram of the first pre-forming of the flange-side pipe fitting;

[0025] Figure 3 A diagram showing the positions of the pads and alignment plates for returning the press to their proper place.

[0026] Figure 4 This is a schematic diagram showing the position of the flange edge during forming;

[0027] Figure 5 This is a schematic diagram of the inner mold installation.

[0028] Figure 6 This is a schematic diagram showing the connection between the inner mold and the sealing punch.

[0029] The components include: 1. Control system; 2. High-pressure source; 3. Upper mold; 4. Lower mold; 5. Inner mold; 6. Shaping plate; 7. Pad block; 8. Sealing punch. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The present invention provides a hydraulic forming apparatus for pipe fittings with flanges, characterized in that it comprises: a pipe, a worktable, and a forming device;

[0033] The forming device is fixedly installed on the workbench. After the forming device closes the mold, it forms a groove with a flange edge. The pipe is placed in the groove and processed to form a flange edge. The inner mold 5 of the forming device is set inside the pipe.

[0034] The forming device also includes a high-pressure source 2, an upper mold 3, a lower mold 4, a sealing punch 8, and a press; the upper mold 3 is driven and mounted on the bottom surface of the press, and the press is used to provide the closing force when the mold is closed;

[0035] The lower mold 4 is fixedly installed on the worktable;

[0036] The inner mold 5 is tightly fitted to a sealing punch 8 at each end; the two ends of the pipe are respectively sealed and connected to the two sealing punches 8; the high-pressure source 2 is connected to the inner cavity of the pipe.

[0037] High pressure source 2 is used to generate outward expansion pressure in the inner cavity of the pipe.

[0038] The sealing punch 8 is sealed to the pipe through an O-ring; the sealing punch 8 is also connected to the sealing cylinder via a transmission mechanism.

[0039] It is also equipped with a control system 1; the control system 1 controls the lifting and lowering of the upper mold 3 through the press, and then the flange edge is formed by the forming guide of the inner mold 5 and the closing of the upper mold 3; the control system 1 controls the feeding of the sealing punch 8 through the sealing cylinder; the control system 6 controls the pressure supply of the high pressure source 2.

[0040] A shaping pressure plate 6 and / or a pad 7 are also provided between the pipe and the upper mold 3; the shaping pressure plate 6 and the pad 7 are used to control the formation of the top of the pipe and the forming of the flange edge, respectively.

[0041] A hydroforming method for pipe fittings with flange edges includes the following steps:

[0042] S1 equipment is debugged, and the tube blank is placed on the lower mold 4;

[0043] Furthermore, in this step, the control system 1 needs to be used to test whether the press, high pressure source 2, and sealing punch 8 can work normally. If they can work normally, continue to the next step. If there is a fault, the fault should be eliminated before proceeding to the next step.

[0044] S2 places the inner mold 5 inside the tube blank and uses the sealing punch 8 to complete the axial sealing of the tube blank, ensuring no pressure leakage and completing the assembly and positioning of the inner mold 5 at the same time.

[0045] Further, this step involves placing one end of the inner mold 5 into the groove of the sealing punch 8 on one side. A tube blank with suitable properties is then passed through the inner mold 5, with one end positioned at the sealing punch 8 already fitted with the inner mold 5. At this point, the main body of the inner mold 5 is completely placed within the tube blank's cavity. After one end of the tube blank is assembled with the sealing punch 8 of the inner mold 5, the control system 1 controls the other sealing punch 8 to feed, causing it to contact the corresponding end of the tube blank. As the sealing punch 8 feeds further, the inner mold 5 closest to that sealing punch 8 enters the groove of the sealing punch 8, completing the sealing of both ends of the tube blank while simultaneously positioning the inner mold 5.

[0046] S3 controls the high-pressure source 2 to inject low-pressure liquid into the tube blank through the control system 1;

[0047] Further, the specific operation of this step is as follows: after the sealing punch 8 completes the sealing of the tube blank, the control system 1 controls the high-pressure source 2 to inject low-pressure liquid into the tube blank to check whether the seal is complete. If the seal is complete, proceed to the next step; if there is pressure leakage, repair it until a complete seal is achieved before proceeding to the next step.

[0048] S4 controls the high-pressure source 2 through the control system 1 to generate high-pressure liquid, which plays a supporting role in the inner cavity of the tube blank; the pressure in the inner cavity of the tube blank is constant; and the upper mold 3 is driven by the press to descend and close with the lower mold 4, and cooperate with the inner mold 5 to initially form the flange structure.

[0049] S5 uses control system 1 to control the press to return to its original position, the sealing punch 8 to its original position, and the high-pressure source 2 to stop generating high-pressure liquid, and removes the inner mold 5. Place the pad 7 and the shaping plate 6 on the initially formed flange edge, and use control system 1 to control the press to descend until the flange edge is formed;

[0050] S6 completes mold closing, resets all equipment, and removes the tube blank.

[0051] Furthermore, after completing this step, the control system 1 is used to control the press to rise back to the initial position, and the workpiece with the flange edge is taken out. Measuring tools are used to measure whether the wall thickness is evenly distributed, the flange length, the flange thickness, etc. meet the design requirements. If they all meet the design requirements, the forming is successful.

[0052] In one embodiment of the present invention, the tube blank is a DP590 high-strength steel hydraulically formed pipe fitting. The tube blank has a diameter of 50mm, a wall thickness of 2mm, a length of 200mm, and an actual forming length of 100mm. The yield strength of DP590 high-strength steel is 570MPa, therefore the initial yield pressure of the tube blank is... The pressure is 46.8 MPa, meaning the internal pressure supporting the tube blank should be less than 46.8 MPa. The clamping force F required for mold closure... c =p c A p ×10 -3 It is 290.16 kN.

[0053] Furthermore, for details regarding the positioning method of the inner mold 5, please refer to [link / reference]. Figure 5 and Figure 6 The inner mold 5 serves as an internal positioning plate. To ensure that it does not shift along the axial direction of the pipe or perpendicular to the axial direction, a positioning method in which the sealed pipe end is embedded in the inner mold 5 is adopted. This design achieves both the positioning of the inner mold 5 and the stability of the inner mold 5 during the forming process.

[0054] Furthermore, the inner mold 5 has a flat rectangular parallelepiped structure.

[0055] Furthermore, compared with existing stamping and welding processes, the workpieces obtained using this hydraulic forming method are superior to the former in terms of mechanical properties, forming time, and lightweight structure.

[0056] Furthermore, traditional stamping and welding processes require several steps to form integral hollow components with flanges, which means multiple sets of molds and longer forming times. This invention can form integral hollow components with flanges in a single process, thus reducing production costs and improving production efficiency.

[0057] Since the stamping and welding process involves welding two stamped parts together to obtain a shaped workpiece, its mechanical properties are inevitably lower than those of a single workpiece obtained by internal high-pressure forming.

[0058] In stamping and welding forming processes, the welding step increases the weight of the workpiece. In the forming process of this invention, the workpiece weight remains unchanged. Through reasonable structural design, the workpiece weight obtained using this invention is lower than that of stamped and welded workpieces.

[0059] Due to the inherent welding characteristics of the stamping and welding process, the formed workpiece usually has assembly flanges on both sides. However, when assembling the workpiece with other structural components, usually only one side flange is needed, which not only wastes materials but also increases the weight of the vehicle body. This invention allows for the direct forming of a single-sided assembly flange, thereby improving material utilization and reducing material waste.

[0060] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0061] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A hydraulic forming apparatus for pipe fittings with flange edges, characterized in that, include: Pipes, workbenches, and forming equipment; The forming device is fixedly installed on the workbench. After the forming device closes the mold, it forms a groove. The pipe is placed in the groove and processed to form a flange edge. The inner mold (5) of the forming device is provided inside the pipe. The forming device also includes a high-pressure source (2), an upper mold (3), a lower mold (4), a sealing punch (8), and a press; the upper mold (3) is driven and mounted on the bottom surface of the press, and the press is used to provide the mold closing force when the mold is closed; The lower mold (4) is fixedly installed on the worktable; The inner mold (5) is tightly fitted to a sealing punch (8) at each end; the two ends of the pipe are respectively sealed and connected to the two sealing punches (8); the high pressure source (2) is connected to the inner cavity of the pipe.

2. The hydraulic forming apparatus for a flanged pipe fitting according to claim 1, characterized in that: The high-pressure source (2) is used to generate outward expansion pressure in the inner cavity of the pipe.

3. The hydraulic forming apparatus for a flanged pipe fitting according to claim 2, characterized in that: The sealing punch (8) is sealed to the pipe by an O-ring; the sealing punch (8) is connected to the sealing cylinder for transmission.

4. The hydraulic forming apparatus for a flanged pipe fitting according to claim 3, characterized in that: A control system (1) is also provided; the control system (1) controls the upper mold (3) to rise and fall through the press, and then the flange edge is formed by the forming guide of the inner mold (5) and the closing of the upper mold (3); the control system (1) controls the feeding of the sealing punch (8) through the sealing cylinder; the control system (1) controls the pressure supply of the high pressure source (2).

5. The hydraulic forming apparatus for a flanged pipe fitting according to claim 1, characterized in that: A shaping pressure plate (6) and a pad (7) are also provided between the pipe and the upper mold (3); the shaping pressure plate (6) and the pad (7) are used to control the formation of the top of the pipe and the forming of the flange edge, respectively.

6. A method for hydroforming a pipe fitting with a flange, employing the hydroforming apparatus for a pipe fitting with a flange as described in any one of claims 1-5, characterized in that, Includes the following steps: S1 equipment is debugged, and the pipe is placed on the lower mold; S2 places the inner mold inside the pipe and uses a sealing punch to axially seal the pipe, ensuring no pressure leakage and simultaneously assembling and positioning the inner mold. S3 controls the high-pressure source to inject low-pressure liquid into the pipe through the control system; S4 controls the high-pressure source through the control system to generate high-pressure liquid, which provides support in the inner cavity of the pipe; the pressure in the inner cavity of the pipe is constant; and the upper mold is driven by the press to descend and close with the lower mold, which, together with the inner mold, forms the initial shape of the flange edge structure; S5 uses the control system to control the press to return to its original position, the sealing punch to its original position, and the high-pressure source to stop generating high-pressure liquid, and removes the inner mold; place a pad and a shaping plate on the initially formed flange edge, and use the control system to control the press to descend until the flange edge is formed; S6 completes mold closing, resets all equipment, and removes the pipe.

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