Method and device for manufacturing large-sized thin-walled tubular part by gas-liquid internal high pressure forming

Abstract

A method and device for manufacturing a large-sized thin-walled tubular part by gas-liquid internal high pressure forming (IHPF). A gas and a liquid are filled at a certain volume ratio into a thin-walled blank. The pressure of the gas-liquid mixed fluid is mainly determined by the gas pressure. During the deformation of the thin-walled blank, due to a large compression ratio of the gas, the gas-liquid pressure will not basically change with the change of the volume of a blank cavity. A support pressure on the cavity of the thin-walled blank is stable in the entire forming process. In addition, even if there is a slight leakage of the liquid or gas during the forming process, the medium pressure inside the blank will not fluctuate largely. In this way, embodiments lower the requirements for the sealing effect during the tubular part forming process.

Claims

1. A method for manufacturing a thin-walled tubular part by gas-liquid internal high pressure forming, comprising the following steps: analyzing a characteristic of the thin-walled part to be formed, and determining an internal support pressure of a blank for formation of the thin walled tubular part; calculating a cavity volume of the blank and a change in the cavity volume of the blank during the formation; determining a filling sequence of a gas medium and a liquid medium to be placed into the blank and a volume ratio of the gas medium and the liquid medium to be placed into the blank according to the change in the cavity volume of the blank; placing the blank on a die, and closing the die to a certain position; sealing two ends of the blank; filling a certain volume of the liquid medium into the blank; filling the gas medium into the blank such that an internal pressure of the blank reaches the internal support pressure of the blank; closing the die completely to deform the blank, and monitoring the internal pressure of the blank in real time; adjusting the internal pressure of the blank by adding or discharging the gas medium or the liquid medium, when the internal pressure of the blank exceeds or falls below the internal support pressure of the blank until the thin-walled tubular part is formed; keeping the die closed until after the thin-walled tubular part is formed, and quickly releasing the gas medium to release the internal pressure of the blank; and opening the die and taking out the thin-walled tubular part that was formed.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) To describe the technical solutions in the examples of the present invention or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the examples. Apparently, the accompanying drawings in the following description merely show some examples of the present invention, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

(2) FIG. 1 is a structural diagram for step 4 of a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF according to an embodiment of the present invention.

(3) FIG. 2 is a structural diagram for step 5 of a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF according to an embodiment of the present invention.

(4) FIG. 3 is a structural diagram for step 6 of a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF according to an embodiment of the present invention.

(5) FIG. 4 is a structural diagram for step 7 of a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF according to an embodiment of the present invention.

(6) FIG. 5 is a structural diagram for step 8 of a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF according to an embodiment of the present invention.

(7) Reference Numerals: 1. upper die, 2. lower die, 3. left pressure pad, 4. right pressure pad, 5. upper die shoe, 6. lower die shoe, 7. liquid storage tank, 8. first punch, 9. gas storage tank, 10. second punch, 11. blank, 12. liquid, and 13. gas.

DETAILED DESCRIPTION

(8) The following clearly and completely describes the technical solutions in the examples of the present invention with reference to the accompanying drawings in the examples of the present invention. Apparently, the described examples are merely some rather than all of the examples of the present invention. All other examples obtained by a person of ordinary skill in the art based on the examples of the present invention without creative efforts shall fall within the protection scope of the present invention.

(9) One objective of the present invention is to provide a method and device for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF, so as to solve the problems existing in the prior art.

(10) To make the above objectives, features, and advantages of the present invention more obvious and easy to understand, embodiments and examples of the present invention will be further described in detail with reference to the accompanying drawings and the detailed description.

Example 1

(11) This example provides a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF, including the following steps:

(12) Step 1, determine an internal pressure: analyze a characteristic of a part to be formed, and determine an internal support pressure for forming.

(13) Step 2, calculate a volume: calculate a cavity volume of a blank 11 and a change in the volume during the entire forming process.

(14) Step 3, determine a gas-liquid volume ratio: determine a sequence and a volume ratio of a gas medium and a liquid medium for filling into the blank 11 according to the change in the cavity volume of the blank 11.

(15) Step 4, place the blank 11: place the large-sized thin-walled blank 11 to be formed on a die, and close the die to a certain position, as shown in FIG. 1.

(16) Step 5, seal an end: seal an end of the blank 11, as shown in FIG. 2.

(17) Step 6, fill the liquid: fill the blank 11 with a certain volume of liquid 12, as shown in FIG. 3.

(18) Step 7, fill the gas: fill the blank 11 with the gas 13 until a set pressure is achieved in the blank 11, as shown in FIG. 4.

(19) Step 8, close the die for forming: close the die completely to deform the blank 11, and monitor the internal pressure of the blank 11 in real time, as shown in FIG. 5.

(20) Step 9, adjust the pressure: adjust the pressure by filling the blank 11 with or discharging from the blank 11 the gas or liquid, when the internal pressure of the blank 11 exceeds or falls below the set pressure.

(21) Step 10, release the pressure: keep the die closed after the forming is completed, and quickly release the gas to release the pressure in the blank 11.

(22) Step 11, open the die to obtain a tubular part: open the die, and take out a formed tubular part.

Example 2

(23) As shown in FIG. 4, this example provides a device for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF, applied to the method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF in Example 1. The forming device specifically includes a die, a liquid filling device and a gas filling device. The liquid filling device and the gas filling device are used to fill a blank 11 with a liquid and a gas, respectively. The die includes an upper die 1, a lower die 2, a left pressure pad 3 and a right pressure pad 4. The upper die 1 is provided on the top of the lower die 2. An upper die shoe 5 is provided on the top of the upper die 1, and a lower die shoe 6 is provided at the bottom of the 5 lower die 2. The left pressure pad 3 and the right pressure pad 4 are provided on both sides of the upper die 1, respectively. The liquid filling device includes a liquid storage tank 7 and a first punch 8. The liquid storage tank 7 is connected to the first punch 8 through a pipe. The first punch 8 fills the blank 11 with the liquid from the liquid storage tank 7. The gas filling device includes a gas storage tank 9 and a second punch 10. The gas storage tank 9 is connected to the second punch 10 through a pipe. The second punch 10 fills the blank 11 with the gas from the gas storage tank 9. In this example, the first punch 8 and the second punch 10 are respectively connected to both ends of the blank 11, which realizes the filling of the liquid or gas and seals the both ends of the blank 11.

Example 3

(24) This example provides a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF. In step 2, the cavity volume of the blank and the cavity volume of the final part are calculated, but the change in the volume during the entire forming process is not calculated. Other steps are the same as those of Example 1.

(25) This example has the beneficial effect that it is not necessary to calculate the volume change of the large-sized tubular part in the entire process or to adjust the pressure in real time. For a large-sized thin-walled tubular part, the cavity volume of the blank reaches 100 L or more, and the change in the cavity volume of the blank during the press forming process is only 10-20% of the raw volume. Because the gas compression ratio is large, the relative change of the gas pressure in the blank cavity is only 10-25%. Such a change in the gas pressure will not adversely affect the forming process, so there is no need to adjust the support pressure in real time based on the volume change of the blank cavity during the entire forming process.

Example 4

(26) This example provides a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF. In step 6, about 50-100 L of liquid is filled into the blank. Other steps are the same as those of Example 1.

(27) This example has the beneficial effect that the large-sized tubular part uses the liquid to occupy a space and the gas to provide pressure, which realizes high efficiency and a low cost. A large volume of liquid is first filled into the large-sized thin-walled tubular part and then the gas is filled into the remaining space of the tubular part. That is, the liquid first occupies most of the space and then the gas is filled to provide a support pressure. In this way, this example of the present invention solves the problems of long gas filling and releasing time and low production efficiency caused by a large volume and a high gas pressure in the blank cavity during a “gas-filled pressing” process which uses only gas for internal support. In addition, this example of the present invention also avoids the preparation and control of high-pressure high-flow gas, thereby saving investment in equipment and usage costs.

Example 5

(28) This example provides a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF. In step 6, the liquid filled into the blank is water or an emulsion, and the volume of the liquid is 50-75% the cavity volume of the blank. Other steps are the same as those of Example 1.

(29) This example has the beneficial effect that the gas volume is large and the internal support pressure is stable. Because the volume of the gas filled into the blank cavity is large, the internal support pressure of the blank remains basically unchanged in the process of closing the die to deform the blank. When it is not necessary to use a variable internal support pressure to form a part, this solution solves the problem regarding a sharp drop or rise in the pressure due to liquid leakages or compression in a conventional method which uses only liquid for support. In addition, this solution completes the process of closing the die for forming at a fast speed in 3-5 seconds, improving the efficiency.

Example 6

(30) This example provides a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF. In step 6, the liquid placed into the blank is water or an emulsion, and the volume of the liquid is 80-90% the cavity volume of the blank. Other steps are the same as those of Example 1.

(31) This example has the beneficial effect that the gas volume is small and the pressure can be adjusted quickly. The volume of the liquid placed in the blank cavity is larger than the volume of the gas placed in the blank cavity. Therefore, when a small amount of gas is directly added or released, the support pressure of the blank cavity can be adjusted to a large extent, and the pressure adjustment is stable and accurate. In this way, this example of the present invention solves the problem regarding difficulty in achieving precise pressure adjustment by adding to or discharging from the blank a liquid when only the liquid is used for support.

Example 7

(32) This example provides a method for manufacturing a large-sized thin-walled tubular part by gas-liquid IHPF. In step 9, the liquid is discharged or added from the bottom of the cavity of the thin-walled blank, or the gas is discharged or added from an upper portion, and the cavity pressure is adjusted by changing the liquid volume or directly changing the gas pressure. Other steps are the same as those of Example 1.

(33) This example has the beneficial effect that the internal pressure is adjusted accurately and in real time during the entire forming process, which meets the requirements for forming a complex part. The cavity of the thin-walled blank is simultaneously filled with a gas and a liquid according to a certain volume ratio. Because the gas has a large compression ratio, the pressure of the cavity can be smoothly adjusted by changing the liquid volume to changing the volume and pressure of the gas, or directly changing the gas pressure. In this way, this example of the present invention solves the problem that when only the liquid is used for internal support, it is difficult to precisely adjust the pressure by changing the liquid volume because the liquid is almost incompressible. Meanwhile, during the entire forming process, the support pressure in the blank cavity can be adjusted quickly or slowly, and can be gradually changed according to a specific curve, which provides the possibility for forming a complex thin-walled tubular part.

(34) Several examples are used for illustration of the principles and implementation methods of the present invention. The description of the examples is used to help illustrate the method and the core principles of the present invention. In addition, those skilled in the art can make various modifications in terms of specific examples and scope of application in accordance with the teachings of the present invention. In conclusion, the content of this specification shall not be construed as a limitation to the present invention.