Large cross-section pipe filling and composite forming method and device

Abstract

The application provides a large-section differential pipe liquid filling composite forming method and device, relates to the technical field of metal pipe forming, and the large-section differential pipe liquid filling composite forming method comprises the following steps: step one, plate material blank is subjected to liquid filling deep drawing forming to form a conical shell; step two, the closed end of the conical shell is cut to obtain a conical pipe with open ends; and step three, the conical pipe is subjected to liquid filling pressure forming to obtain a target pipe. The application further provides a large-section differential pipe liquid filling composite forming device. The large-section differential pipe liquid filling composite forming method and device provided by the application can improve the size precision and quality of the pipe.

Description

Technical Field

[0001] This invention relates to the field of metal pipe forming technology, and in particular to a liquid-filled composite forming method and apparatus for large cross-section differential pipe fittings. Background Technology

[0002] Current technology indicates that it is difficult to achieve integral forming of pipe fittings with large cross-sectional differences. Due to the large cross-sectional differences and complex structures of the fittings, the industry often adopts a technique of forming individual sections and then assembling them by welding to obtain pipe fittings with large cross-sectional differences. However, because the fittings have weld seams, microcracks or even cracking failures can easily occur at the weld seams during service due to stress concentration. In addition, since the individual sections are formed, the thermal stress generated during welding causes warping deformation in the weld area, which seriously affects the dimensional accuracy of the fittings.

[0003] Internal high-pressure forming is an advanced technology for manufacturing integral hollow pipe fittings, offering significant advantages in both structural and material lightweighting. However, when using internal high-pressure forming for large-section differential pipe fittings, the pipe material must first be pre-formed to obtain a suitable pre-formed billet shape. But due to the presence of localized features in this billet, the required internal pressure during forming is excessively high, causing the process to become overly reliant on high-tonnage forming equipment, thus limiting its application in the processing of large-section differential pipe fittings. Furthermore, during internal high-pressure forming, the pre-formed billet undergoes circumferential tensile deformation, inevitably resulting in wall thinning along the thickness direction. For profiles with localized features, the wall thickness distribution is not uniform. Therefore, there is an urgent need to provide a new forming device and method for large-section differential pipe fittings to address the aforementioned problems in the existing technology. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for liquid filling composite forming of large cross-section differential pipe fittings, so as to solve the problems existing in the prior art and improve the dimensional accuracy and quality of the pipe fittings.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a method for liquid-filled composite molding of large cross-section differential pipe fittings, such as... Figures 2-5 As shown, it includes:

[0007] Step 1: The sheet metal blank is subjected to liquid-filled deep drawing to form a conical shell;

[0008] Step 2: Cut off the closed end of the conical shell to obtain a conical tube with open ends;

[0009] Step 3: Hydraulically pressurize the tapered tube to obtain the target pipe fitting.

[0010] Preferably, before step one, it is also necessary to determine the liquid-filling deep drawing forming die, the pressure ring, the liquid filling chamber, the liquid-filling forming die, and the sealing assembly based on the size and structure of the target pipe fitting.

[0011] Preferably, step one includes:

[0012] Step a: Inject the fluid medium from the external hydraulic pump into the filling chamber through the filling port;

[0013] Step b: Place the sheet blank on the surface of the die above the filling chamber;

[0014] Step c: Control the pressing ring to move down to contact the sheet blank using the press, and apply pressing force after contact with the sheet blank;

[0015] Step d: Use the hydraulic system to pressurize the fluid medium in the filling chamber through the filling hole, so that the plate blank is tightly attached to the surface of the punch.

[0016] Step e: The punch moves downward under the control of the press, driving the sheet metal blank into the filling chamber for deep drawing;

[0017] Step f: The fluid medium scatters and flows out from the gap between the upper end face of the filling chamber and the plate blank to the outer edge of the blank flange area, forming fluid lubrication;

[0018] Step g: After the deep drawing process is completed, unload the pressure in the filling chamber, control the punch and blank holder to move upward, and remove the conical shell.

[0019] Preferably, step three includes:

[0020] Step a: Measure the external dimensions and wall thickness of the initial conical tube, and calculate the required internal support pressure of the conical tube during hydraulic forming;

[0021] Step b: Place the tapered tube in the lower die, and simultaneously feed the left and right sealing punches axially to ensure a reliable seal at both ends of the tapered tube;

[0022] Step c: The high-pressure fluid medium is injected into the inner cavity of the tapered tube through the high-pressure fluid channel of the sealing punch, and is loaded according to the set internal pressure loading path until the pressure value reaches the preset tapered tube support internal pressure;

[0023] Step d: Under the drive of the press, the upper die presses and shapes the tapered tube according to the set pressing amount;

[0024] Step e: Unload the internal pressure, retract the sealing punches at both ends, return the upper die, and remove the formed tube;

[0025] Step f: Remove the process transition sections on both sides of the formed pipe to obtain the target pipe.

[0026] This invention also provides a liquid-filled composite forming device for large cross-section differential pipe fittings, including a liquid-filled deep drawing forming die, a pressure ring, a liquid filling chamber, a liquid-filled forming die, and a sealing assembly; the liquid-filled deep drawing forming die, the liquid-filled forming die, and the pressure ring are all fixedly connected to a press in sequence according to the process; the liquid-filled deep drawing forming die and the liquid-filled forming die are respectively provided with forming cavities for forming a conical shell and a target pipe fitting; the liquid filling chamber is fixedly connected to the lower working end of the press, and has a liquid filling hole at the bottom; the sealing assembly is connected to a booster oil circuit.

[0027] Preferably, the liquid-filled deep drawing die includes a punch and a die; the punch is positioned above the liquid filling chamber and corresponds to the opening of the forming cavity formed by the liquid filling chamber and the die; the punch is assembled at the upper end of the liquid filling chamber.

[0028] Preferably, the hydraulic forming mold is a split structure and includes an upper mold and a lower mold respectively; the upper mold is assembled on the upper working end of the press, and the pressing amount of the upper mold is controlled by the press; the lower mold is assembled on the lower working end of the press.

[0029] Preferably, the sealing assembly includes sealing punches mounted at both ends of the hydraulic forming mold, and Y-shaped sealing rings and rubber sealing gaskets mounted inside the sealing punches. The sealing punches are divided into an internal guide section and an external guide section, and a high-pressure fluid channel is provided inside the sealing punches on either side, and the high-pressure fluid channel is connected to the booster oil circuit.

[0030] Preferably, the internal guide section of the sealing punch is configured to transitionally fit with the tube blank cavity.

[0031] Preferably, the outer guide section of the sealing punch is configured with a clearance fit to the forming cavity.

[0032] The present invention achieves the following technical effects compared to the prior art:

[0033] The present invention provides a method and apparatus for liquid-filled composite forming of large-section differential pipe fittings, employing a composite forming process combining liquid-filled deep drawing and liquid-filled forming technologies. This enables seamless integral forming of large-section differential pipe fittings. Compared to welding assembly methods, the pipe fittings produced by this composite forming process are free of weld seams, enhancing the overall mechanical properties of the fittings and avoiding defects caused by welding thermal stress, thus effectively improving dimensional accuracy. Furthermore, the friction between the pipe blank and the mold changes from "impeding material flow to local features" in internal high-pressure forming to "promoting material flow to local features," significantly improving the wall thickness distribution across different sections of the target pipe fitting and reducing forming pressure. This method is suitable for mass production of large-section differential pipe fittings formed by liquid-filled composite forming. Attached Figure Description

[0034] 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.

[0035] Figure 1 This is a structural schematic diagram of the sheet metal blank;

[0036] Figure 2 This is a schematic diagram of the conical shell structure;

[0037] Figure 3 This is a schematic diagram of the tapered tube structure;

[0038] Figure 4 This is a structural schematic diagram of the target pipe fitting;

[0039] Figure 5 A schematic diagram of the hydraulic forming mold structure;

[0040] Figure 6 Schematic diagram of the hydraulic forming sealing punch structure;

[0041] In the diagram: 1-Inflation forming mold, 11-Upper mold, 12-Lower mold, 2-Tube blank, 3-Sealing punch, 31-Internal guide section, 32-External guide section. Detailed Implementation

[0042] 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.

[0043] The purpose of this invention is to provide a method and apparatus for liquid filling composite forming of large cross-section differential pipe fittings, so as to solve the problems existing in the prior art and improve the dimensional accuracy and quality of the pipe fittings.

[0044] 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.

[0045] The structural diagram of the sheet blank is as follows: Figure 1 As shown, it is a circular plate.

[0046] Example 1

[0047] This embodiment provides a method for liquid-filled composite molding of large cross-section differential pipe fittings, including:

[0048] Step 1: The sheet metal blank is subjected to liquid-filled deep drawing to form a conical shell, such as... Figure 2 As shown.

[0049] Step 2: Cut off the closed end of the conical shell to obtain a conical tube with open ends, such as... Figure 3 As shown.

[0050] Step 3: Perform hydraulic forming on the tapered tube to obtain the target pipe fitting, such as... Figure 4 As shown.

[0051] Before step one, it is also necessary to determine the liquid-filling deep drawing forming die, pressure ring, liquid filling chamber, liquid-filling forming die and sealing assembly based on the size and structure of the target pipe fitting.

[0052] Step one includes:

[0053] Step a: Inject the fluid medium from the external hydraulic pump into the filling chamber through the filling port;

[0054] Step b: Place the sheet blank on the surface of the die above the filling chamber;

[0055] Step c: Control the pressing ring to move down to contact the sheet blank using the press, and apply pressing force after contact with the sheet blank;

[0056] Step d: Use the hydraulic system to pressurize the fluid medium in the filling chamber through the filling hole, so that the plate blank is tightly attached to the surface of the punch.

[0057] Step e: The punch moves downward under the control of the press, driving the sheet metal blank into the filling chamber for deep drawing;

[0058] Step f: The fluid medium scatters and flows out from the gap between the upper end face of the filling chamber and the plate blank to the outer edge of the blank flange area, forming fluid lubrication;

[0059] Step g: After the deep drawing process is completed, unload the pressure in the filling chamber, control the punch and blank holder to move upward, and remove the conical shell.

[0060] Step three includes:

[0061] Step a: Measure the external dimensions and wall thickness of the initial conical tube, and calculate the required internal support pressure of the conical tube during hydraulic forming;

[0062] Step b: Place the tapered tube in the lower die, and simultaneously feed the left and right sealing punches axially to ensure a reliable seal at both ends of the tapered tube;

[0063] Step c: The high-pressure fluid medium is injected into the inner cavity of the tapered tube through the high-pressure fluid channel of the sealing punch, and is loaded according to the set internal pressure loading path until the pressure value reaches the preset tapered tube support internal pressure;

[0064] Step d: Under the drive of the press, the upper die presses and shapes the tapered tube according to the set pressing amount;

[0065] Step e: Unload the internal pressure, retract the sealing punches at both ends, return the upper die, and remove the formed tube.

[0066] The liquid-filled composite forming method for large-section differential pipe fittings provided in this embodiment employs a composite forming process combining liquid-filled deep drawing and liquid-filled forming technologies, enabling seamless integral forming of large-section differential pipe fittings. Compared to welding assembly methods, the pipe fittings produced by this composite forming process are free of weld seams, which not only enhances the overall mechanical properties of the pipe fittings but also avoids defects caused by welding thermal stress during the welding process, effectively improving the dimensional accuracy of the pipe fittings. Furthermore, the frictional force between the pipe blank 2 and the mold changes from "impeding material flow to local features" in internal high-pressure forming to "promoting material flow to local features," thereby significantly improving the wall thickness distribution of each section of the target pipe fitting and reducing the forming pressure. This method is suitable for the mass production of liquid-filled composite forming of large-section differential pipe fittings.

[0067] Example 2

[0068] This embodiment provides a liquid-filled composite forming device for large cross-section differential pipe fittings, such as... Figures 5-6 As shown, the device includes a liquid-filled deep drawing forming die, a blank holder, a liquid filling chamber, a liquid-filled forming die 1, and a sealing assembly. The liquid-filled deep drawing forming die, the liquid-filled forming die 1, and the blank holder are all fixedly connected to the press in sequence according to the process. The liquid-filled deep drawing forming die and the liquid-filled forming die 1 are respectively provided with forming cavities for forming conical shells and target pipes. The liquid filling chamber is fixedly connected to the lower working end of the press and has a liquid filling hole at the bottom. The sealing assembly is connected to the pressurization oil circuit.

[0069] The liquid-filled deep drawing die includes a punch and a die; the punch is placed above the liquid filling chamber and corresponds to the opening of the forming cavity formed by the liquid filling chamber and the die; the punch is assembled at the upper end of the liquid filling chamber.

[0070] like Figure 5 As shown, the hydraulic forming mold 1 is a split structure and includes an upper mold 11 and a lower mold 12. The upper mold 11 is assembled on the upper working end of the press, and the pressing amount of the upper mold 11 is controlled by the press. The lower mold 12 is assembled on the lower working end of the press.

[0071] The sealing assembly includes sealing punches 3 mounted at both ends of the hydraulic forming mold 1, and Y-shaped sealing rings and rubber sealing gaskets mounted inside the sealing punches 3. The sealing punches 3 are divided into an internal guide section 31 and an external guide section, and a high-pressure fluid channel is opened inside the sealing punches 3 on either side. The high-pressure fluid channel is connected to the booster oil circuit.

[0072] The liquid-filled composite forming device for large-section differential pipe fittings provided in this embodiment employs a composite forming process combining liquid-filled deep drawing and liquid-filled forming technologies, enabling seamless integral forming of large-section differential pipe fittings. Compared to welding assembly methods, the pipe fittings produced by this composite forming process are free of weld seams, which not only enhances the overall mechanical properties of the pipe fittings but also avoids defects caused by welding thermal stress during the welding process, effectively improving the dimensional accuracy of the pipe fittings. Furthermore, the frictional force between the pipe blank 2 and the mold changes from "impeding material flow to local features" in internal high-pressure forming to "promoting material flow to local features," thereby significantly improving the wall thickness distribution of each section of the target pipe fitting and reducing the forming pressure. This device is suitable for the mass production of liquid-filled composite forming of large-section differential pipe fittings.

[0073] In some embodiments, the internal guide section 31 of the sealing punch is configured to transition fit with the tube blank cavity. Both ends of the tube blank 2 are reserved with process transition sections. The sealing punch 3 is used to seal the middle cavity of the tube blank 2 at both ends of the tube blank 2. After the punching and forming is completed, the process transition sections at both ends are cut off to obtain the target pipe fitting.

[0074] In some embodiments, the outer guide section 32 of the sealing punch is configured with a clearance fit with the forming cavity.

[0075] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for liquid-filled composite molding of large cross-section differential pipe fittings, characterized in that: include: Step 1: The sheet metal blank is subjected to liquid-filled deep drawing to form a conical shell; Step 2: Cut off the closed end of the conical shell to obtain a conical tube with open ends; Step 3: Hydraulically pressurize the tapered tube to obtain the target pipe fitting.

2. The method for liquid filling and composite forming of large cross-section differential pipe fittings according to claim 1, characterized in that: Before step one, it is necessary to determine the liquid-filling deep drawing forming die, the blank holder, the liquid filling chamber, the liquid-filling forming die, and the sealing assembly based on the size and structure of the target pipe fitting.

3. The method for liquid filling and composite forming of large cross-section differential pipe fittings according to claim 2, characterized in that: Step one includes: Step a: Inject the fluid medium from the external hydraulic pump into the filling chamber through the filling port; Step b: Place the sheet blank on the surface of the die above the filling chamber; Step c: Control the pressing ring to move down to contact the sheet blank using the press, and apply pressing force after contact with the sheet blank; Step d: Use the hydraulic system to pressurize the fluid medium in the filling chamber through the filling hole, so that the plate blank is tightly attached to the surface of the punch. Step e: The punch moves downward under the control of the press, driving the sheet metal blank into the filling chamber for deep drawing; Step f: The fluid medium scatters and flows out from the gap between the upper end face of the filling chamber and the plate blank to the outer edge of the blank flange area, forming fluid lubrication; Step g: After the deep drawing process is completed, unload the pressure in the filling chamber, control the punch and blank holder to move upward, and remove the conical shell.

4. The method for liquid filling and composite forming of large cross-section differential pipe fittings according to claim 2, characterized in that: Step three includes: Step a: Measure the external dimensions and wall thickness of the initial conical tube, and calculate the required internal support pressure of the conical tube during hydraulic forming; Step b: Place the tapered tube in the lower die, and simultaneously feed the left and right sealing punches axially to ensure a reliable seal at both ends of the tapered tube; Step c: The high-pressure fluid medium is injected into the inner cavity of the tapered tube through the high-pressure fluid channel of the sealing punch, and is loaded according to the set internal pressure loading path until the pressure value reaches the preset tapered tube support internal pressure; Step d: Under the drive of the press, the upper die presses and shapes the tapered tube according to the set pressing amount; Step e: Unload the internal pressure, retract the sealing punches at both ends, return the upper die, and remove the formed tube; Step f: Remove the process transition sections on both sides of the formed pipe to obtain the target pipe.

5. A device for liquid-filled composite forming of large cross-section differential pipe fittings according to any one of claims 1 to 4, characterized in that: The system includes a liquid-filled deep drawing forming die, a blank holder, a liquid filling chamber, a liquid-filled forming die, and a sealing assembly. The liquid-filled deep drawing forming die, the liquid-filled forming die, and the blank holder are all fixedly connected to the press in sequence according to the process. The liquid-filled deep drawing forming die and the liquid-filled forming die are respectively provided with forming cavities for forming conical shells and target pipes. The liquid filling chamber is fixedly connected to the lower working end of the press and has a liquid filling hole at the bottom. The sealing assembly is connected to the pressurization oil circuit.

6. The large cross-section differential pipe fitting liquid filling composite forming device according to claim 5, characterized in that: The liquid-filled deep drawing die includes a punch and a die; the punch is positioned above the liquid filling chamber and corresponds to the opening of the forming cavity formed by the liquid filling chamber and the die; the punch is assembled at the upper end of the liquid filling chamber.

7. The large cross-section differential pipe fitting liquid filling composite forming device according to claim 6, characterized in that: The hydraulic forming mold is a split structure and includes an upper mold and a lower mold; the upper mold is assembled on the upper working end of the press, and the pressing amount of the upper mold is controlled by the press; the lower mold is assembled on the lower working end of the press.

8. The large cross-section differential pipe fitting liquid filling composite forming device according to claim 7, characterized in that: The sealing assembly includes sealing punches mounted at both ends of the hydraulic forming mold, and Y-shaped sealing rings and rubber sealing gaskets mounted inside the sealing punches. The sealing punches are divided into an internal guide section and an external guide section, and a high-pressure fluid channel is provided inside the sealing punches on either side. The high-pressure fluid channel is connected to the booster oil circuit.

9. The large cross-section differential pipe fitting liquid filling composite forming device according to claim 8, characterized in that: The internal guide section of the sealing punch is configured to transitionally fit with the tube blank cavity.

10. The large cross-section differential pipe fitting liquid filling composite forming device according to claim 8, characterized in that: The outer guide section of the sealing punch is configured with a clearance fit to the forming cavity.

Images