A method for forming a pressure and flow guiding type clamp pressure pipe

Abstract

The present application relates to a kind of card pressure pipe forming methods of guiding pressure and flow, which is by setting the guiding pressure and flow hole at the low-pressure forming section of punch, during the expansion of punch, the liquid in the liquid channel in punch enters into the low-pressure forming section of punch through the guiding pressure and flow hole, and enters into the inner wall of die cavity and the outer wall of pipe blank between;So that the liquid pressure inside and outside pipe blank is equal, so as to prevent pipe blank from swelling deformation under the action of internal and external pressure;The punch of greater friction resistance or the punch of high-pressure sealing section that first contact with the end of pipe blank will push the axial movement of pipe blank, until the high-pressure sealing section of two groups of punch is contacted with the end of pipe blank, and the centering of pipe blank is realized;Two groups of punch continue to move towards each other, while increasing the injection amount of liquid medium, so that the liquid medium between the inner wall of pipe blank and the high-pressure sealing section of punch promotes the swelling deformation of the forming site of pipe blank, until the outside of the forming site cooperates with the inner wall of die cavity, so as to complete the forming of card pressure pipe.

Description

Technical Field

[0001] This invention relates to a method for processing crimp tubes, specifically a method for forming pressure-conducting and flow-conducting crimp tubes. Background Technology

[0002] Internal high-pressure forming is an advanced manufacturing technology for producing hollow integral components. Its principle involves using a tube as the blank and water or other liquid as the transmission medium. High-pressure water is injected into the tube, creating pressure on the inner wall. A punch seals both ends of the tube, and axial feed provides material for forming, ensuring the outer wall of the tube completely adheres to the mold cavity, thus obtaining the desired shape. The forming of press-fit tubes is primarily achieved using internal high-pressure forming. A press-fit tube includes a sealing tube body at the end, which is a radially outward protrusion. The mold cavity includes an annular arc cavity for forming the sealing tube body. Existing punches include a low-pressure sealing section for low-pressure pre-expansion of the tube blank, a high-pressure sealing section for high-pressure expansion of the tube blank, and an annular body connected to the high-pressure sealing section. The front end of the annular body has an arc-shaped forming surface. When the punch is pushed forward to its final position, the forming surface becomes part of the annular arc cavity. The production process of the press-fit tube is as follows: (1) After locking the fixed mold and the moving mold, the power cylinders located on both sides of the fixed mold and the moving mold drive the punch to insert into the inner cavity of the tube blank. At the same time, liquid medium is injected into the tube through the liquid channel inside the punch to exhaust the air; (2) During the insertion of the punch into the tube blank, the flared section at the front end of the punch causes the tube blank to expand and stick to the inner wall of the mold cavity. The low-pressure sealing surface is established by using the reasonable setting between the gap between the mold cavity and the low-pressure sealing section of the punch and the tube blank wall thickness, and low pressure is formed in the tube blank; (3) When the arc-shaped forming surface of the punch reaches the position of the annular arc cavity, it becomes part of the annular arc cavity. Under the mechanical force of the punch and the high pressure of the liquid medium, a high-pressure sealing surface is formed, which causes the tube blank to expand and fully fit with the inner wall of the mold cavity to form the tube blank.

[0003] During the synchronous, opposite-direction movement of the two sets of punches, factors such as misalignment of the tube blank placement, tube blank diameter tolerance, material thickness deviation, and differences in the clearance between the punch and the die cavity can easily lead to different frictional forces and flaring resistance when the two sets of punches are inserted into the tube blank, resulting in different insertion depths. When the clearance between the punch, the die cavity, and the tube blank decreases after the punch is inserted into the tube blank, the shear force difference formed by the injection pressure and overflow pressure of the liquid inside the tube blank increases. For tube blanks made of materials with low yield strength (such as copper, carbon steel, aluminum, etc.), the shear force difference formed by the injection pressure and overflow pressure of the liquid exceeds the yield strength of the material itself, causing the tube blank to expand and deform. This causes the outer wall of the tube blank to press against the inner wall of the die cavity, making it impossible for the tube blank to move under the thrust of the punch. Thus, the tube blank cannot move freely within the die cavity and cannot be aligned. Conversely, if the tube blank can move freely within the mold cavity, the punch with a greater depth of penetration into the tube blank will exert a pushing force on the tube blank. This pushing force will cause the tube blank to move towards the punch with a smaller depth of penetration into the tube blank, ultimately making the depth of penetration of the two sets of punches into the tube blank consistent (i.e., achieving centering of the compression tube in the mold cavity), ensuring that the compression molding of both sides of the tube blank can be successfully completed.

[0004] The current approach to solving the above problems is to increase the gap between the low-pressure sealing section of the punch, the die cavity, and the tube blank. This prevents the shear force difference between the injection pressure and the overflow pressure of the liquid from increasing, making the material less prone to expansion and deformation. In other words, the tube blank can move axially under the thrust of the punch, thus ensuring that the punch penetrates the tube blank to the same depth. This method reduces the fluctuation of the shear force difference caused by the injection and overflow pressures of the liquid by increasing the gap between the punch, die cavity, and tube blank. This prevents materials with low yield strength (such as copper, carbon steel, and aluminum) from expanding and deforming. During the synchronous movement of the two sets of punches, the thrust of the punches causes the tube blank to move within the die cavity, thus ensuring that the two sets of punches penetrate the tube blank to the same depth. However, this method has limitations and instability for press-fit tube forming with high flaring accuracy requirements or small gaps between the punch, die cavity, and tube blank, and with low yield strength materials (such as copper, carbon steel, and aluminum). Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a pressure-guided flow-guided crimping tube forming method. This method can reduce the shear force difference between the injection pressure and the overflow pressure in the tube blank, making the internal and external liquid pressures of the tube blank equal. This allows the tube blank to move freely axially under the thrust of the punch, achieving automatic centering of the tube blank. This ensures that the depth to which the punches on both sides of the tube blank enter the tube blank is consistent, thereby guaranteeing the quality of the processed crimping tube.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0007] A method for forming a pressure-conducting and flow-guiding crimp tube includes the following steps:

[0008] (1) Place the tube blank on the fixed mold, then drive the moving mold to move towards the fixed mold, and complete the mold locking between the moving mold and the fixed mold;

[0009] (2) Drive two sets of punches to enter the mold cavity of the mold from both ends of the mold simultaneously and inject liquid medium at the same time; when the flared section of the punch contacts the tube opening of the tube blank, as the punch continues to move, the flared section at the front end of the punch will cause the tube opening of the tube blank to expand and deform; the diameter of the low-pressure sealing section located behind the flared section in the punch is smaller than the maximum diameter of the flared section.

[0010] (3) During the process of the two sets of punches moving towards each other in the tube blank, before the high-pressure sealing section of the punch contacts the end of the tube blank, the liquid medium injected from the liquid channel of the punch advances in two paths. One path enters the inner cavity of the tube blank axially from the water injection port at the end of the punch; while the other path enters the gap between the low-pressure sealing section of the punch and the tube blank through the pressure guiding hole set at the low-pressure sealing section of the punch, and bypasses the end of the tube blank to enter between the inner wall of the mold cavity and the outer wall of the tube blank, so that the inner cavity of the tube blank and the mold cavity form a connected body, thereby making the inside of the tube blank in a low-pressure state and the liquid pressure inside and outside the tube blank equal, so that the tube blank will not be tightly stretched on the inner wall of the mold cavity.

[0011] (4) The two sets of punches continue to move toward each other until the lengths of the two sets of punches inserted into the tube blank are equal and the high-pressure sealing sections are in contact with the end of the tube blank. During this process, if the high-pressure sealing section of one set of punches contacts the end of the tube blank first, the punch will push the tube blank to move axially until the high-pressure sealing sections of both sets of punches are in contact with the end of the tube blank, thereby achieving automatic centering of the tube blank.

[0012] (5) The two sets of punches move towards each other to apply axial force to both ends of the tube blank. The high-pressure sealing section of the punch and the end of the tube blank form a high-pressure sealing zone to prevent the liquid medium from flowing between the inner wall of the mold cavity and the outer wall of the tube blank. The pressure of the liquid medium increases continuously, causing the forming part in the forming cavity of the tube blank to expand and deform until the outer wall of the forming part is in contact with the inner wall of the forming cavity, thereby completing the forming process of the press tube.

[0013] Preferably, in step (4), when the high-pressure sealing section of one set of punches first contacts the end of the tube blank, the liquid medium enters the gap between the low-pressure sealing section of the other set of punches and the tube blank from the pressure guiding hole in the other set of punches, and bypasses the end of the corresponding tube blank to enter between the inner wall of the mold cavity and the outer wall of the tube blank. Before the two sets of punches extend into the tube blank to the same length and the high-pressure sealing section contacts the end of the tube blank, the tube blank is still in a low-pressure non-deformation expansion state.

[0014] Preferably, an annular groove is provided between the low-pressure sealing section of the punch and the flared section of the punch, and the pressure guiding hole is connected to the annular groove. After the liquid medium enters the annular groove from the pressure guiding hole, it is distributed in the circumferential direction and then enters the gap between the low-pressure sealing section of the punch and the tube blank.

[0015] Preferably, there are multiple pressure guiding holes, which are arranged along the circumference of the annular groove, and the liquid medium flows through the multiple pressure guiding holes into the annular groove.

[0016] Preferably, the axial direction of the pressure guiding orifice is perpendicular to the axial direction of the liquid channel inside the punch.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The pressure-guiding and flow-guiding crimping tube forming method of the present invention provides pressure-guiding and flow-guiding holes on the low-pressure sealing section of the punch. The diameter of the low-pressure sealing section located behind the flaring section of the punch is smaller than the maximum diameter of the flaring section. During the flaring process, a portion of the liquid medium in the liquid channel within the punch enters the inner cavity of the tube blank, while the other portion enters through the pressure-guiding and flow-guiding holes between the low-pressure sealing section of the punch and the inner wall of the tube blank, bypassing the end of the tube blank and entering between the inner wall of the mold cavity and the outer wall of the tube blank. The inner cavity of the tube blank and the mold cavity form a pressure communication body, and the liquid pressure at the two locations is equal. Therefore, during the flaring process, the tube blank, in addition to expanding with the punch, is also subjected to pressure-guiding and flow-guiding holes. Apart from the deformation of the nozzle section, the tube blank does not expand between the two punches. Even for tube blanks made of materials with low yield strength, the internal and external liquid pressures are equal, so the tube blank will not expand or deform and will not tighten against the inner wall of the mold cavity. If the two sets of punches enter the tube blank to different depths during the punch flaring process, the punch with excessive frictional resistance or the punch whose high-pressure sealing section contacts the end of the tube blank first can push the tube blank to move past the other set of punches. Since the two sets of punches move synchronously towards each other, when the high-pressure sealing sections of both sets of punches contact the end of the tube blank, the tube blank can be aligned, thus ensuring that the depth of the two sets of punches entering the tube blank is consistent, thereby guaranteeing the quality of the processed crimped tube.

[0019] 2. The pressure-guiding and flow-guiding type crimp tube forming method of the present invention can guide the liquid medium inside the punch into the flared section of the punch through the pressure-guiding and flow-guiding hole on the punch, thereby increasing the contact area between the liquid medium and the flared section of the punch, thereby improving the cooling effect and extending the service life of the punch.

[0020] 3. The pressure-guided flow type press-fit tube forming method of the present invention, through the pressure-guided flow holes on the punch, allows the liquid medium inside the punch to still enter the flaring section of the punch through the pressure-guided flow holes even if the gap between the inner wall of the mold cavity and the tube blank, and between the inner wall of the tube blank and the punch, becomes smaller. This achieves lubrication between the flaring section of the punch and the inner wall of the tube blank, reduces the frictional resistance experienced by the flaring section of the punch during the flaring process, and extends the service life of the punch. At the same time, the liquid medium coming out from the pressure-guided flow holes can enter between the inner wall of the mold cavity and the outer wall of the tube blank. While balancing the liquid pressure inside and outside the tube blank, it can also achieve lubrication between the outer wall of the tube blank and the inner wall of the mold cavity, so as to facilitate the punch to push the tube blank to move and achieve the centering of the tube blank.

[0021] 4. The pressure-guiding and flow-guiding tube forming method of the present invention balances the pressure on the inner and outer sides of the tube blank by setting pressure-guiding and flow-guiding holes, avoiding the tube blank from expanding and tightening between the tube blank and the mold cavity during the flaring stage. Therefore, it is not necessary to prevent the tube blank from expanding by increasing the gap between the low-pressure sealing section of the punch, the mold cavity, and the tube blank as in the prior art, which is beneficial to improving the forming accuracy of the tube blank. Attached Figure Description

[0022] Figures 1-4 This is a schematic diagram of four different states of the pressure-guiding and flow-guiding crimping tube forming method of the present invention.

[0023] Figure 5 This is a schematic diagram of liquid medium flow.

[0024] Figure 6 This is a schematic diagram of the punch structure. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0026] See Figures 1-6 ,in, Figure 1 This is a schematic diagram showing the structure of two sets of punches 1 entering the mold in opposite directions after the mold is locked. Figure 2 This is a schematic diagram of the structure in which the high-pressure sealing section 101 of the right punch 1 first contacts the end of the tube blank 4; Figure 3 This is a schematic diagram showing that the high-pressure sealing section 101 of the punches 1 on both the left and right sides is in contact with the end of the tube blank 4. Figure 4 This is a schematic diagram of the final formed structure of tube blank 4; Figure 5 This is a schematic diagram of liquid medium flow. Figure 6 This is a schematic diagram of the three-dimensional structure of punch 1.

[0027] See Figures 1-6 The pressure-guiding and flow-guiding crimping tube forming method of the present invention includes the following steps:

[0028] (1) Place the tube blank 4 on the fixed mold 3, then drive the moving mold 2 to move towards the fixed mold 3, and complete the mold locking between the moving mold 2 and the fixed mold 3.

[0029] (2) Drive two sets of punches 1 to enter the mold cavity of the mold from both ends of the mold simultaneously and inject liquid medium at the same time; when the flared section 106 on the punch 1 contacts the tube opening of the tube blank 4, as the punch 1 continues to move, the flared section 106 at the front end of the punch 1 will cause the tube opening of the tube blank 4 to expand and deform; the diameter of the low-pressure sealing section 102 located behind the flared section 106 in the punch 1 is smaller than the maximum diameter of the flared section 106.

[0030] (3) During the process of the two sets of punches 1 moving towards each other in the tube blank 4, before the high pressure sealing section 101 of the punch 1 contacts the end of the tube blank 4, the liquid medium injected from the liquid channel 105 of the punch 1 advances in two paths. One path enters the inner cavity of the tube blank 4 axially from the water injection port at the end of the punch 1; while the other path enters the gap between the low pressure sealing section 102 of the punch 1 and the tube blank 4 through the pressure guiding and flow guiding hole 104 set at the low pressure sealing section 102 of the punch 1, and bypasses the end of the tube blank 4 to enter between the inner wall of the mold cavity and the outer wall of the tube blank 4, so that the inner cavity of the tube blank 4 and the mold cavity form a connected body, thereby making the inside of the tube blank 4 in a low pressure state and the liquid pressure inside and outside the tube blank 4 equal, so that the tube blank 4 will not be tightened on the inner wall of the mold cavity.

[0031] (4) The two sets of punches 1 continue to move towards each other until the lengths of the two sets of punches 1 extending into the tube blank 4 are equal and the high-pressure sealing sections 101 are in contact with the end of the tube blank 4. During this process, if the high-pressure sealing section 101 of one set of punches 1 contacts the end of the tube blank 4 first, the punch 1 will push the tube blank 4 to move axially until the high-pressure sealing sections 101 of both sets of punches 1 are in contact with the end of the tube blank 4, thereby achieving automatic centering of the tube blank 4.

[0032] (5) The two sets of punches 1 move towards each other to apply axial force to both ends of the tube blank 4. The high pressure sealing section 101 of the punch 1 and the end of the tube blank 4 form a high pressure sealing zone to prevent the liquid medium from flowing between the inner wall of the mold cavity and the outer wall of the tube blank 4. The pressure of the liquid medium increases continuously, causing the forming part in the forming cavity of the tube blank 4 to expand and deform until the outer wall of the forming part is in contact with the inner wall of the forming cavity, thereby completing the forming process of the press tube.

[0033] See Figures 1-6In step (4), when the high-pressure sealing section 101 of one set of punches 1 first contacts the end of the tube blank 4, the liquid medium enters the gap between the low-pressure sealing section 102 of the other set of punches 1 and the tube blank 4 from the pressure guiding hole 104 in the other set of punches 1, and bypasses the end of the corresponding tube blank 4 to enter between the inner wall of the mold cavity and the outer wall of the tube blank 4. Before the two sets of punches 1 extend into the tube blank 4 to equal lengths and the high-pressure sealing section 101 contacts the end of the tube blank 4, the tube blank 4 is still in a low-pressure non-deformation expansion state.

[0034] See Figures 1-6 An annular groove 103 is provided between the low-pressure sealing section 102 and the flaring section 106 of the punch 1. A pressure guiding hole 104 communicates with the annular groove 103. Liquid medium enters the annular groove 103 from the pressure guiding hole 104 and is distributed circumferentially before entering the gap between the low-pressure sealing section 102 of the punch 1 and the tube blank 4. By providing this structure, the liquid medium flowing out of the pressure guiding hole 104 fills the annular groove and applies pressure evenly to the inner wall of the tube blank 4 along the radial direction of the annular groove, causing the tube blank 4 to expand and deform uniformly outward, thereby improving the flaring quality.

[0035] See Figures 1-6 There are multiple pressure guiding holes 104, and the multiple pressure guiding holes 104 are arranged along the circumferential direction of the annular groove.

[0036] See Figures 1-6 The axial direction of the pressure guiding hole 104 is perpendicular to the axial direction of the liquid channel 105 inside the punch 1.

[0037] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for forming a pressure and flow guiding type press-fit tube, characterized by, The method comprises the following steps: (1) placing a pipe blank on a fixed die, then driving a movable die to move towards the fixed die, and locking the movable die and the fixed die; (2) driving two groups of punches to synchronously enter a cavity of the die from two ends of the die, and simultaneously injecting liquid medium; when a flared section on the punch contacts a pipe opening of the pipe blank, with continuous movement of the punch, the flared section at the front end of the punch promotes the pipe opening of the pipe blank to be deformed and expanded; a low-pressure sealing section behind the flared section of the punch has a diameter smaller than a maximum diameter of the flared section; (3) during opposite movement of the two groups of punches in the pipe blank, before the high-pressure sealing section of the punch contacts an end of the pipe blank, liquid medium injected from the liquid channel of the punch advances in two paths, one of which enters an inner cavity of the pipe blank in an axial direction from a water injection opening at the end of the punch, and the other of which enters a gap between the low-pressure sealing section of the punch and the pipe blank through a pressure and flow guide hole arranged at the low-pressure sealing section of the punch, and then bypasses the end of the pipe blank to enter between an inner wall of the cavity of the die and an outer wall of the pipe blank, so that the inner cavity of the pipe blank and the cavity of the die form a communication body, and then the inside of the pipe blank is in a low-pressure state and the liquid pressures inside and outside the pipe blank are equal, so that the pipe blank is not tightly expanded on the inner wall of the cavity of the die; (4) the two groups of punches continue to move towards each other until the two groups of punches are inserted into the pipe blank by an equal length and the high-pressure sealing sections of the two groups of punches contact the ends of the pipe blank; during the process, if the high-pressure sealing section of one of the two groups of punches first contacts the end of the pipe blank, the punch pushes the pipe blank to move axially until the high-pressure sealing sections of the two groups of punches contact the ends of the pipe blank, so that the pipe blank is automatically centered; (5) the two groups of punches further move towards each other to apply axial force to the two ends of the pipe blank, a high-pressure sealing area is formed between the high-pressure sealing section of the punch and the end of the pipe blank to prevent the liquid medium from flowing between the inner wall of the cavity of the die and the outer wall of the pipe blank, the pressure of the liquid medium continuously increases, the forming part of the pipe blank located in the forming cavity is deformed and expanded, until the outer wall of the forming part is attached to the inner wall of the forming cavity, so that the forming and processing of the clamp pipe is completed.

2. The pressure and flow guided clamping tube forming method according to claim 1, wherein In step (4), when the high-pressure sealing section of one of the two groups of punches first contacts the end of the pipe blank, liquid medium enters the gap between the low-pressure sealing section of the other punch and the pipe blank through the pressure and flow guide hole in the punch, and then bypasses the end of the corresponding pipe blank to enter between the inner wall of the cavity of the die and the outer wall of the pipe blank, so that the pipe blank is still in a low-pressure non-deformation and expansion state before the two groups of punches are inserted into the pipe blank by an equal length and the high-pressure sealing sections of the two groups of punches contact the ends of the pipe blank.

3. The pressure and flow guided pinch tube forming method of claim 1, wherein, The low-pressure sealing section of the punch is provided with an annular groove between the flared section of the punch and the low-pressure sealing section of the punch, the pressure and flow guide hole is in communication with the annular groove, and the liquid medium entering the annular groove from the pressure and flow guide hole is distributed in a circumferential direction and then enters the gap between the low-pressure sealing section of the punch and the pipe blank.

4. The pressure conducting and flow conducting type clip pressure pipe forming method according to claim 1, characterized by, The pressure and flow guide hole is a plurality of pressure and flow guide holes, the plurality of pressure and flow guide holes are arranged in the circumferential direction of the annular groove, and the liquid medium flows through the plurality of pressure and flow guide holes to enter the annular groove.

5. The pressure conducting and flow conducting type clip pressure pipe forming method according to claim 1, characterized by, The axis direction of the pressure and flow guide hole is perpendicular to the axis direction of the liquid channel in the punch.

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