Internal expansion fluid forming device and forming method thereof

Abstract

The present invention is applicable to the technical field of hydraulic bulging, and provides an internal bulging fluid forming device and a forming method thereof, wherein the device comprises a cylinder body, a piston, an outer sealing ring, a downward pressure cavity body and a connecting mechanism; the cylinder body is filled with a fluid medium, and a plurality of outer sealing rings are arranged between the cylinder body and the piston; a central through hole is processed on the piston; a cavity is processed at the center of the downward pressure cavity body, and a mold is installed in the cavity; the connecting mechanism is arranged between the piston and the downward pressure cavity body. A pressed piston can be selectively installed in the central through hole, and a plurality of inner sealing rings are arranged between the central through hole and the pressed piston. The top of the pressed piston is processed with a shape matching the mold. The present invention ensures that the sheet metal will not leak fluid even if thinning occurs during the forming process by keeping the edge of the sheet metal in a dynamic compression state between the piston and the downward pressure cavity body. The present invention adopts an internal bulging fluid forming process, which can realize the diversification of sheet metal forming shapes.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic bulging, and in particular relates to an internal bulging fluid forming device and a forming method thereof. Background Art

[0002] At present, the commonly used hydraulic fluid bulging sheet metal curved surface forming method is to press the edge of the sheet metal on a sealed container that can withstand high pressure, pass fluid into the container, and use a punch to press down on the upper surface of the sheet metal, forcing the sheet metal to expand and deform while forcing the fluid to flow out of the container, thereby forming the desired curved surface shape. The role of the fluid is an auxiliary support role; another fluid bulging forming method is to increase the fluid pressure and fluid volume in a closed container, forcing the sheet metal to bulge outward and gradually form the desired shape. However, both of the above forming methods require changing the volume of the fluid. The Chinese invention patent with publication number CN115634993B proposes a floating type pressure edge hydraulic bidirectional single-die deep drawing forming device and forming method. In the deep drawing process, the method uses the piston of the pressure edge ring to drive the sheet metal to be stretched in the opposite direction. The biggest feature of this technology is that it does not change the volume of the fluid in the closed cavity but realizes the deformation of the sheet metal by changing its flow shape, which saves half of the displacement of the punch of the traditional deep drawing forming.

[0003] However, this patent still has some shortcomings. The floating technology of the blank holder may cause liquid leakage as the sheet metal becomes thinner. At the same time, since it uses the situation where the punch presses downward, the formed part enters the piston hole, making it difficult to remove the part. At the same time, the size of the hole limits the diversity of the shapes of the formed parts. Therefore, an internal expansion fluid forming device and a forming method thereof are proposed. Summary of the invention

[0004] The object of the present invention is to provide an internal expansion fluid forming device and a forming method thereof, aiming to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An internal expansion fluid forming device comprises a cylinder body, a piston, an outer sealing ring, a downward pressure cavity body and a connecting mechanism; the cylinder body is filled with a fluid medium, and a plurality of outer sealing rings are arranged between the cylinder body and the piston; a central through hole is machined on the piston; a cavity is machined at the center of the downward pressure cavity body, and a mold is installed in the cavity; the connecting mechanism is arranged between the piston and the downward pressure cavity body.

[0007] Furthermore, the connecting mechanism includes a stepped slot and a stepped cylinder, the stepped slot is provided on the lower pressure cavity, and the stepped cylinder is fixed on the piston.

[0008] Furthermore, a pressed piston is installed in the central through hole, and a plurality of inner sealing rings are installed between the central through hole and the pressed piston.

[0009] Furthermore, the top of the pressed piston is processed into a shape matching the mold.

[0010] A sheet metal forming method using the internal expansion fluid forming device as described above, when the central through hole is not equipped with a pressed piston, the method comprises the following steps:

[0011] S1: Assemble the sheet material to be formed between the top of the piston and the lower end of the downward pressure cavity;

[0012] S2: External force pushes the downward pressure cavity downward, and the downward pressure cavity pushes the piston downward to increase the pressure of the fluid medium in the cylinder. As the pressure increases, the fluid medium flows upward through the central through hole and squeezes the sheet material;

[0013] S3: Continue to increase the external force. When the pressure of the fluid medium exceeds the strength of the plastic deformation of the sheet metal, the sheet metal deforms and enters the mold until it is completely fitted with the mold cavity to obtain a sheet metal formed part.

[0014] S4: lift the downward pressure cavity body, and overlap the stepped cylinder with the stepped slot through the connecting mechanism to drive the piston to lift at the same time, the pressure in the cylinder body is reduced, and the fluid medium flows back into the cylinder body from the central through hole of the piston. At this time, the downward pressure cavity body is rotated to separate the stepped cylinder from the stepped slot, thereby disengaging the piston, and then further lift the downward pressure cavity body to take out the sheet metal formed part from the mold of the downward pressure cavity body.

[0015] Further, when a pressed piston is installed in the central through hole, the method comprises the following steps:

[0016] S1: Assemble the sheet material to be formed between the top of the piston and the lower end of the downward pressure cavity;

[0017] S2: External force pushes the downward pressure cavity downward, and the downward pressure cavity pushes the piston downward to increase the pressure of the fluid medium in the cylinder. As the pressure increases, the fluid medium pushes the pressed piston to move upward along the central through hole, and the pressed piston begins to squeeze the sheet;

[0018] S3: The external force continues to increase, and the pressed piston continues to move upward, forcing the sheet metal to deform and gradually fit into the mold cavity until it is completely fitted into the mold cavity to obtain a sheet metal formed part;

[0019] S4: lift the downward pressure cavity body, and overlap the stepped cylinder with the stepped slot through the connecting mechanism to drive the piston to lift at the same time, so that the pressure of the fluid medium in the cylinder body is reduced, and the pressed piston drops by itself under the action of its own gravity. At this time, the downward pressure cavity body is rotated to separate the stepped cylinder from the stepped slot, so that the piston is disengaged, and the downward pressure cavity body is further lifted, and the sheet metal formed part is taken out from the mold of the downward pressure cavity body.

[0020] Furthermore, the fluid medium is a mixture of one or more components of hydraulic oil, pure water, salt water, and acid or alkaline solution.

[0021] Furthermore, the sheet material is one or a composite of metal and polymer material, the metal is one or more of steel, copper, aluminum alloy and magnesium alloy, and the polymer material is one or more of PC and PE.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention ensures that the edge of the sheet material is always in a dynamic compression state between the piston and the downward pressure cavity, thereby ensuring that the sheet material will not leak fluid even if it is thinned during the forming process.

[0024] 2. The present invention adopts an internal expansion fluid forming process, which can realize the diversification of sheet metal forming shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the internal expansion fluid forming device.

[0026] Figure 2 The present invention is a schematic diagram of the structure of an internal expansion fluid forming device equipped with a compressed piston.

[0027] Figure 3 The figures are schematic diagrams of sheet metal forming when the internal expansion fluid forming device is not equipped with a pressed piston; (a) is a schematic diagram of the fluid medium starting to squeeze the sheet metal when the device is not equipped with a pressed piston; (b) is a schematic diagram of the sheet metal deforming and entering the mold when the device is not equipped with a pressed piston; (c) is a schematic diagram of the deformed sheet metal completely fitting into the mold cavity when the device is not equipped with a pressed piston.

[0028] Figure 4 The schematic diagrams are of the sheet metal forming action when the internal expansion fluid forming device is equipped with a pressed piston; (a) is a schematic diagram of the device being equipped with a pressed piston and the pressed piston starting to squeeze the sheet metal; (b) is a schematic diagram of the device being equipped with a pressed piston and the sheet metal being deformed and entering the mold; (c) is a schematic diagram of the device being equipped with a pressed piston and the deformed sheet metal being completely fitted with the mold cavity.

[0029] Figure 5It is a schematic diagram of the connection and disconnection between the downward pressure cavity body and the piston through a rotating connection mechanism, wherein (a) is a schematic diagram of the connection state; (b) is a schematic diagram of the disconnection state.

[0030] Figure 6 The present invention is a flow chart of a sheet metal forming method implemented by an internal expansion type fluid forming device; wherein (a) is a flow chart of a sheet metal forming method implemented by an internal expansion type fluid forming device not equipped with a compressed piston; and (b) is a flow chart of a sheet metal forming method implemented by an internal expansion type fluid forming device equipped with a compressed piston.

[0031] In the figure: cylinder body 1, piston 2, outer sealing ring 3, downward pressure cavity body 4, central through hole 201, fluid medium 5, cavity 401, mold 402, sheet material 6, inner sealing ring 7, pressed piston 8, stepped groove 901, stepped cylinder 902. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0034] like Figure 1 and Figure 5 As shown, an internal expansion fluid forming device provided by an embodiment of the present invention includes a cylinder body 1, a piston 2, an outer sealing ring 3, a downward pressure cavity body 4 and a connecting mechanism; the interior of the cylinder body 1 is filled with a fluid medium 5, and a plurality of outer sealing rings 3 are arranged between the cylinder body 1 and the piston 2; a central through hole 201 is machined on the piston 2; a cavity 401 is machined in the center of the downward pressure cavity body 4, and a mold 402 is installed in the cavity 401; the connecting mechanism is arranged between the piston 2 and the downward pressure cavity body 4.

[0035] The connection mechanism includes a stepped slot 901 and a stepped cylinder 902 . The stepped slot 901 is provided on the lower pressure cavity 4 , and the stepped cylinder 902 is fixed on the piston 2 .

[0036] In the embodiment of the present invention, the setting of the connection mechanism will not affect the assembly of the plate 6 , and the edge diameter of the plate 6 can be reduced or a groove can be opened at the contact portion with the connection mechanism to avoid the stepped cylinder 902 .

[0037] The external force pushes the downward pressure cavity body 4 downward, and the downward pressure cavity body 4 pushes the piston 2 downward to increase the pressure of the fluid medium 5 in the cylinder. As the pressure in the cylinder body 1 increases, the fluid medium 5 flows upward through the central through hole 201 and begins to squeeze the sheet material 6. When the external force pushing the downward pressure cavity body 4 is further increased, the pressure of the fluid medium 5 exceeds the strength of the plastic deformation of the sheet material 6, and the sheet material 6 is deformed and enters the mold 402. The external force is further increased until the deformed sheet material 6 is completely fitted with the cavity of the mold 402 to obtain a sheet material formed part.

[0038] like Figure 1 and Figure 2 As shown, as a preferred embodiment of the present invention, a pressed piston 8 is installed in the central through hole 201, a plurality of inner sealing rings 7 are installed between the central through hole 201 and the pressed piston 8, and the top of the pressed piston 8 is processed with a shape matching the mold 402 to form a mold-shaped nested mold punch.

[0039] In the embodiment of the present invention, the external force pushes the lower pressure cavity 4 downward, and the lower pressure cavity 4 pushes the piston 2 to move downward to increase the pressure of the fluid medium 5 in the cylinder 1. As the pressure increases, the fluid medium 5 pushes the pressed piston 8 to move upward along the central through hole 201, and the pressed piston 8 begins to squeeze the sheet material 6. As the external force further increases, the pressed piston 8 continues to move upward, forcing the sheet material 6 to deform and gradually fit into the cavity of the mold 402, until the deformed sheet material 6 is completely fitted into the cavity of the mold 402, and a sheet material formed part is obtained.

[0040] like Figure 3 , Figure 5 and Figure 6 As shown in (a), a sheet metal forming method implemented by using the above-mentioned internal expansion fluid forming device is provided in one embodiment of the present invention. When the pressed piston 8 is not installed in the central through hole 201, the method includes the following steps:

[0041] S1: Assemble the sheet material 6 to be formed between the top of the piston 2 and the lower end of the downward pressure cavity 4;

[0042] S2: External force pushes the downward pressure cavity 4 downward, and the downward pressure cavity 4 pushes the piston 2 downward to increase the pressure of the fluid medium 5 in the cylinder. As the pressure in the cylinder 1 increases, the fluid medium 5 flows upward through the central through hole 201 and begins to squeeze the sheet 6 (see Figure 3 (a));

[0043] S3: When the external force pushing down the cavity 4 is further increased, the pressure of the fluid medium 5 exceeds the strength of the plastic deformation of the sheet 6, and the sheet 6 deforms and enters the mold 402 (see Figure 3In (b), the external force is further increased until the deformed sheet 6 is completely fitted into the cavity of the mold 402 (see Figure 3 In (c), a sheet metal forming part is obtained;

[0044] S4: lift the downward pressure cavity body 4, and overlap the stepped groove 901 through the stepped cylinder 902 of the connecting mechanism to drive the piston 2 to be lifted at the same time, the pressure in the cylinder body 1 is reduced, and the fluid medium 5 flows back into the cylinder body 1 from the central through hole 201 of the piston 2. At this time, the downward pressure cavity body 4 is rotated to separate the stepped cylinder 902 from the stepped groove 901, thereby disengaging the piston 2, and then further lift the downward pressure cavity body 4 to take out the sheet metal formed part from the mold 402 of the downward pressure cavity body 4.

[0045] like Figure 4 , Figure 5 and Figure 6 As shown in (b), as a preferred embodiment of the present invention, when a pressed piston 8 is installed in the central through hole 201, the method includes the following steps:

[0046] S1: Assemble the sheet material 6 to be formed between the top of the piston 2 and the lower end of the downward pressure cavity 4;

[0047] S2: External force pushes the lower pressure cavity 4 downward, and the lower pressure cavity 4 pushes the piston 2 to move downward to increase the pressure of the fluid medium 5 in the cylinder 1. As the pressure increases, the fluid medium 5 pushes the pressed piston 8 to move upward along the central through hole 201, and the pressed piston 8 begins to squeeze the sheet 6 (see Figure 4 (a));

[0048] S3: As the external force increases further, the pressed piston 8 continues to move upward, forcing the sheet 6 to deform and gradually fit into the cavity of the mold 402 (see Figure 4 (b)), until the deformed sheet 6 is completely fitted into the cavity of the mold 402 (see Figure 4 In (c), a sheet metal forming part is obtained;

[0049] S4: lift the pressing cavity body 4, and overlap the stepped groove 901 through the stepped cylinder 902 of the connecting mechanism to drive the piston 2 to be lifted at the same time, so that the pressure of the fluid medium 5 in the cylinder body 1 is reduced, and the pressed piston 8 descends by itself under the action of its own gravity. At this time, the pressing cavity body 4 is rotated to separate the stepped cylinder 902 from the stepped groove 901, so that the piston 2 is disengaged, and the pressing cavity body 4 is further lifted, and the sheet metal formed part is taken out from the mold 402 of the pressing cavity body 4.

[0050] like Figure 1 As shown, as a preferred embodiment of the present invention, the fluid medium 5 is a mixture of one or more components of hydraulic oil, pure water, salt water, acid or alkaline solution, etc.

[0051] like Figure 1 As shown, as a preferred embodiment of the present invention, the sheet material 6 is one or a composite of metal and polymer materials, the metal is one or more of steel, copper, aluminum alloy and magnesium alloy, and the polymer material is one or more of PC and PE.

[0052] In the embodiment of the present invention, the above listed materials are only preferred materials, and the metal materials are not limited to steel, copper, aluminum alloy and magnesium alloy, and the polymer materials are not limited to PC and PE.

[0053] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A sheet forming method using an internal expansion fluid forming device, characterized in that: The internal expansion fluid forming device comprises a cylinder body, a piston, an outer sealing ring, a downward pressure cavity body and a connecting mechanism; the cylinder body is filled with a fluid medium, and a plurality of outer sealing rings are installed between the cylinder body and the piston; a central through hole is processed on the piston; a cavity is processed in the center of the downward pressure cavity body, and a mold is installed in the cavity; the connecting mechanism is arranged between the piston and the downward pressure cavity body; the connecting mechanism comprises a stepped slot and a stepped cylinder, the stepped slot is arranged on the downward pressure cavity body, and the stepped cylinder is fixed on the piston; when the pressed piston is not installed in the central through hole, the method comprises the following steps: S1: Assemble the sheet material to be formed between the top of the piston and the lower end of the downward pressure cavity; S2: External force pushes the downward pressure cavity downward, and the downward pressure cavity pushes the piston downward to increase the pressure of the fluid medium in the cylinder. As the pressure increases, the fluid medium flows upward through the central through hole and squeezes the sheet material; S3: Continue to increase the external force. When the pressure of the fluid medium exceeds the strength of the plastic deformation of the sheet metal, the sheet metal deforms and enters the mold until it is completely fitted with the mold cavity to obtain a sheet metal formed part. S4: lift the downward pressure cavity body, and overlap the stepped cylinder with the stepped slot through the connecting mechanism to drive the piston to lift at the same time, the pressure in the cylinder body is reduced, and the fluid medium flows back into the cylinder body from the central through hole of the piston. At this time, the downward pressure cavity body is rotated to separate the stepped cylinder from the stepped slot, thereby disengaging the piston, and then further lift the downward pressure cavity body to take out the sheet metal formed part from the mold of the downward pressure cavity body.

2. The sheet metal forming method according to claim 1, characterized in that: When a pressed piston is installed in the central through hole, a plurality of inner sealing rings are installed between the central through hole and the pressed piston; the top of the pressed piston is processed into a shape matching the mold; the method comprises the following steps: S1: Assemble the sheet material to be formed between the top of the piston and the lower end of the downward pressure cavity; S2: External force pushes the downward pressure cavity downward, and the downward pressure cavity pushes the piston downward to increase the pressure of the fluid medium in the cylinder. As the pressure increases, the fluid medium pushes the pressed piston to move upward along the central through hole, and the pressed piston begins to squeeze the sheet; S3: The external force continues to increase, and the pressed piston continues to move upward, forcing the sheet metal to deform and gradually fit into the mold cavity until it is completely fitted into the mold cavity to obtain a sheet metal formed part; S4: lift the downward pressure cavity body, and overlap the stepped cylinder with the stepped slot through the connecting mechanism to drive the piston to lift at the same time, so that the pressure of the fluid medium in the cylinder body is reduced, and the pressed piston drops by itself under the action of its own gravity. At this time, the downward pressure cavity body is rotated to separate the stepped cylinder from the stepped slot, so that the piston is disengaged, and the downward pressure cavity body is further lifted, and the sheet metal formed part is taken out from the mold of the downward pressure cavity body.

3. The sheet metal forming method according to claim 2, characterized in that: The fluid medium is a mixture of one or more components selected from hydraulic oil, pure water, salt water, and acid or alkali solution.

4. The sheet metal forming method according to claim 2, characterized in that: The sheet material is one or a composite of metal and polymer material, the metal is one or more of steel, copper, aluminum alloy and magnesium alloy, and the polymer material is one or more of PC and PE.

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