Four-way pipe fitting multi-direction hydraulic filling hydraulic forming method and four-way pipe fitting multi-direction hydraulic filling hydraulic forming device

Abstract

The invention provides a four-way pipe fitting multi-direction charging hydraulic forming method and device, and relates to the technical field of pipe fitting forming. The four-way pipe fitting multi-direction charging hydraulic forming method comprises the steps that the diameter of an initial pipe blank and the size of a variable-diameter area of a variable-diameter pipe blank are determined according to the size of a target pipe; internal pressure p1, axial rolling reduction delta 1 and supporting internal pressure p2 are calculated; determining an initial tube blank length; preparing an initial pipe blank; the initial pipe blank is put into an axial charging hydraulic pressing mold for axial pressing, and a variable-diameter pipe blank is obtained; the variable-diameter pipe blank is put into a circumferential charging hydraulic pressing mold for circumferential pressing, and a double-protrusion pipe blank is obtained; and the ends of the protruding parts of the double-protruding pipe blank are removed, and the target pipe is obtained. The forming load is remarkably reduced, the problems that the high-pressure forming pressure in the four-way pipe fitting is high, material supplementing in a middle deformation area is difficult, and the fracture defect is likely to be generated are effectively solved, the situation that branch pipes and a connecting area are thinned and fractured is avoided, and the obtained four-way pipe fitting is uniform in wall thickness, complete in structure and excellent in performance.

Description

Technical Field

[0001] The invention relates to the technical field of pipe fitting forming, and in particular to a multi-directional hydraulic filling forming method and device for a four-way pipe fitting. Background Art

[0002] Lightweight, high-precision, long-life special-shaped thin-walled components, such as four-way pipe fittings, are often used in aviation and aerospace engine piping systems. At present, multi-way pipe fittings are often produced by welding, such as stamping two halves separately for welding, or inserting and welding branches on the main pipe. However, welded pipe fittings have technical disadvantages such as uneven weld quality and post-weld deformation, and stress concentration at the weld of the pipe fittings is prone to fatigue damage and cracking, which seriously affects the reliability of the components. Internal high pressure forming technology is an advanced lightweight forming technology for multi-way pipe fittings. The integral forming of four-way pipe fittings can not only improve the reliability of pipe fittings, but also meet the lightweight requirements of components. However, when using internal high pressure forming to form multi-way pipe fittings, it is difficult to fill the branch pipes in the middle deformation zone of the pipe fittings, the wall thickness is seriously reduced, and cracking defects are easily generated, affecting the product quality, especially for high-strength (high-temperature alloys, martensitic heat-resistant stainless steel, titanium alloys, etc.) and small-diameter (diameter <20mm, diameter-thickness ratio <10) integral four-way pipe fittings. When using internal high pressure forming, very high forming pressure (up to 300MPa or more) is required. For example, when the diameter of the tube blank is 15mm, the wall thickness is 1.5mm, the yield strength is 500MPa, and the tensile strength is 900MPa, if a multi-way pipe fitting with a fillet radius of 3mm is formed by internal high pressure forming, the forming pressure needs to be at least 350MPa. Moreover, high-strength pipes generally have poor plasticity. The high internal pressure during the forming process causes extremely high friction resistance between the tube blank and the mold, making it difficult for the material at both ends to flow into the middle deformation zone, ultimately causing the branch pipes in the middle deformation zone to be prone to cracking defects due to severe wall thinning. Summary of the invention

[0003] The problem to be solved by the present invention is that the existing use of internal high pressure to form an integral four-way pipe fitting not only has a high forming pressure, but also makes it difficult to feed the branch pipes in the middle deformation zone, and is prone to cracking defects. The forming pressure can be effectively reduced, and the integral forming of high-strength and large thickness-to-diameter ratio four-way pipe fittings such as high-temperature alloy stainless steel, martensitic heat-resistant stainless steel, and titanium alloy under low load can be achieved.

[0004] To this end, the present invention provides a multi-directional hydraulic filling forming method for a four-way pipe fitting, comprising the following steps:

[0005] S1. Determine the diameter of the initial tube blank and the size of the diameter-changing zone of the diameter-changing tube blank according to the size of the target tube;

[0006] S2, calculating the internal pressure p1 and the axial reduction amount Δl required for pressing the initial tube into the reduced diameter tube, and the support internal pressure p2 required for pressing the reduced diameter tube into the double-convex tube;

[0007] S3, determining the initial tube length according to the axial reduction amount Δl and the target tube length;

[0008] S4, preparing the initial tube blank;

[0009] S5, placing the initial tube blank into an axial hydraulic pressing die, and performing axial pressing according to the internal pressure p1 and the axial pressing amount Δl to obtain the reduced diameter tube blank;

[0010] S6, placing the reduced diameter tube blank into a circumferential hydraulic pressing die, and performing circumferential pressing according to the support internal pressure p2 to obtain a double-convex tube blank;

[0011] S8, removing the end of the raised portion of the double-raised tube blank to obtain the target tube.

[0012] Optionally, in step S1, the diameter of the initial tube blank is equal to the diameter of the straight tube zone of the target tube, the circumference of the variable diameter zone of the variable diameter tube blank is equal to the circumference of the axial cross section of the target tube branch, and the length of the variable diameter zone is ≤ the diameter of the target tube branch.

[0013] Optionally, in step S2, p s ≤p1≤2p s , p2≤p s , where p s is the yield pressure of the initial tube blank;

[0014]

[0015] Wherein V is the volume of the variable diameter zone of the variable diameter tube blank, η is the average thinning rate, 0≤η≤5%, d0 is the diameter of the initial tube blank, t is the wall thickness of the initial tube blank, and l0 is the length of the variable diameter zone.

[0016] Optionally, in step S3, the initial tube length=the target tube length+Δl.

[0017] Optionally, between step S6 and step S8, the following steps are further included:

[0018] S7, annealing the double-convex tube blank.

[0019] Optionally, removing the end of the raised portion of the double-raised tube blank comprises:

[0020] The two raised ends of the double-raised tube blank are cut with holes and flanging is performed.

[0021] Compared with the prior art, the multi-directional hydraulic filling forming method of the four-way pipe fitting of the present invention has the following beneficial effects:

[0022] The present invention first performs preliminary preparations, first determining the diameter of the initial tube blank used for forming and the size of the variable diameter zone of the variable diameter tube blank formed by the initial tube blank through the axial hydraulic filling forming die according to the size of the variable diameter zone of the variable diameter tube blank and the parameters of the initial tube blank, and then calculating the internal pressure p1 and the axial pressure reduction Δl required for the initial tube blank to be pressed into the variable diameter tube blank in the axial hydraulic filling forming die, and the supporting internal pressure p2 required for the variable diameter tube blank to be pressed into the double convex tube blank in the annular hydraulic filling forming die, and finally calculating the length of the initial tube blank through the axial pressure reduction Δl and the target tube length, preparing the initial tube blank according to the obtained length and diameter of the initial tube blank, completing the preparation work, and placing the initial tube blank in the axial hydraulic filling forming die. The initial tube billet is placed in an axial hydraulic filling die, and axial pressing is performed according to the internal pressure p1 and the axial pressing amount Δl to obtain a reduced diameter tube billet. The internal pressure can ensure that the initial tube billet is always supported outwards during the pressing and shortening process, so as to prevent the initial tube billet from being concave inwards during pressing; the obtained reduced diameter tube billet is then placed in an annular hydraulic filling die, and annular pressing is performed according to the supporting internal pressure p2 to obtain a double-convex tube billet. The supporting internal pressure can ensure that the reduced diameter tube billet is always supported outwards during the pressing process, so as to prevent the reduced diameter tube billet from being concave inwards during pressing. The convex part of the double-convex tube billet is the branch tube of the target tube. The top of the convex part of the double-convex tube billet is removed to obtain the target The invention first axially presses the initial tube blank to shorten the length of the initial tube blank, and the shortened portion protrudes circumferentially in the middle of the initial tube blank to form a reduced diameter tube blank, and the protruding portion is the reduced diameter area of ​​the reduced diameter tube blank, and the reduced diameter area is an annular area, and its two ends are straight tube areas. Subsequently, the annular hydraulic forming die presses the reduced diameter area, and presses the circumferentially surrounding reduced diameter area toward the position of the two branch areas of the target tube, so that the reduced diameter area becomes the two convex parts of the double-convex tube blank, and finally removes the ends of the two convex parts to connect the convex parts with the outside to form a branch pipe, and obtains a four-way tube fitting. In this process, the material used to form the branch pipe comes from the initial tube blank in the axial direction. The circumferential protrusions formed during the pressing process can ensure that there is sufficient material for forming the branch pipe, avoid thinning and cracking of the branch pipe and the connecting area, improve the overall structural integrity of the four-way pipe fitting, and solve the problem of difficulty in filling materials and easy rupture defects in the middle deformation zone of the internal high-pressure formed four-way pipe fitting. The obtained four-way pipe fitting has uniform wall thickness, complete structure and excellent performance. Compared with the existing internal high-pressure forming method, the internal pressure of the present application is generally lower than the yield internal pressure of the pipe during hydraulic forming, and only plays a supporting role. The forming pressure required for the present application is low and the tonnage of the mold pressing equipment required is small. It is suitable for the overall forming of high-strength and large thickness-to-diameter ratio four-way pipe fittings such as high-temperature alloys and stainless steel.

[0023] In addition, in order to solve the above problems, the present invention also provides a four-way pipe fitting multi-directional hydraulic filling forming device, which is used to implement the above-mentioned four-way pipe fitting multi-directional hydraulic filling forming method, and the four-way pipe fitting multi-directional hydraulic filling forming device includes an axial hydraulic filling mold and an annular hydraulic filling mold.

[0024] Optionally, the axial hydraulic filling forming mold includes a first upper mold, a first lower mold, a supporting spring, an upper sealing punch, a lower sealing punch and a limiting bolt. The first upper mold and the first lower mold are respectively provided with a cavity that penetrates the first upper mold and the first lower mold in the vertical direction. The two cavities are used to be connected to form a first mold cavity. The first upper mold is provided with a countersunk hole, and the first lower mold is provided with a threaded hole. The limiting bolt passes through the countersunk hole and is threadedly connected to the threaded hole. The first upper mold is slidably connected to the limiting bolt. The shape of the first mold cavity matches the shape of the reduced diameter tube blank. The initial tube blank is used to be arranged in the first mold cavity. The upper sealing punch and the lower sealing punch are used to seal the two ends of the initial tube blank and to drive the first upper mold and the first lower mold to move toward each other. A first fluid inlet is provided on the upper sealing punch or the lower sealing punch.

[0025] Optionally, the annular hydraulic filling forming mold includes a second upper mold, a second lower mold, a left sealing punch and a right sealing punch. The lower surface of the second upper mold and the upper surface of the second lower mold are respectively provided with groove structures that penetrate the second upper mold and the second lower mold in a horizontal direction. The second upper mold and the second lower mold are used to move towards each other. The two groove structures are used to enclose a second mold cavity. The shape of the second mold cavity matches the shape of the double-protruding tube blank. The reduced diameter tube blank is used to be arranged in the second mold cavity. The left sealing punch and the right sealing punch are used to seal the two ends of the reduced diameter tube blank. A second fluid inlet is provided on the left sealing punch or the right sealing punch.

[0026] Optionally, the multi-directional hydraulic filling forming device for four-way pipe fittings also includes a mold closing and pressing system and a liquid filling and pressurizing system. The mold closing and pressing system is used to press the axial hydraulic filling forming mold or the annular hydraulic filling forming mold, and the liquid filling and pressurizing system is used to fill the mold cavity of the axial hydraulic filling forming mold or the annular hydraulic filling forming mold with liquid.

[0027] Compared with the prior art, the beneficial effects of the multi-directional hydraulic filling forming device for a four-way pipe fitting described in the present invention are substantially the same as the beneficial effects of the multi-directional hydraulic filling forming method for a four-way pipe fitting described above, and will not be described in detail herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is one of the flow charts of the multi-directional hydraulic filling forming method for a four-way pipe fitting according to an embodiment of the present invention;

[0029] Figure 2 This is a second flow chart of the multi-directional hydraulic forming method for a four-way pipe fitting according to an embodiment of the present invention;

[0030] Figure 3 It is a schematic structural diagram of a variable diameter tube blank according to an embodiment of the present invention;

[0031] Figure 4 for Figure 3 Middle DD side view;

[0032] Figure 5 for Figure 3 mid-EE lateral view;

[0033] Figure 6 This is a schematic structural diagram of a double-convex tube blank according to an embodiment of the present invention;

[0034] Figure 7 for Figure 6 Middle FF side view;

[0035] Figure 8 This is a schematic diagram of the structure of the target tube according to an embodiment of the present invention;

[0036] Fig. 9 for Figure 8 Side view of mid-CC;

[0037] Fig.10 This is one of the structural schematic diagrams of the axial liquid filling forming die according to an embodiment of the present invention;

[0038] Fig.11 This is a second structural schematic diagram of the axial liquid filling forming die according to an embodiment of the present invention;

[0039] Fig.12 This is one of the structural schematic diagrams of the annular hydraulic filling forming die according to an embodiment of the present invention;

[0040] Fig.13 for Fig.12 Middle AA side view;

[0041] Fig.14 This is a second structural schematic diagram of the annular hydraulic filling forming die according to an embodiment of the present invention;

[0042] Fig.15 for Fig.14 Middle BB side view;

[0043] Fig.16 It is a structural schematic diagram of the axial hydraulic filling forming device of the cross-way pipe fitting according to an embodiment of the present invention;

[0044] Fig.17It is a structural schematic diagram of the circumferential hydraulic filling forming device for a four-way pipe fitting according to an embodiment of the present invention.

[0045] Description of reference numerals:

[0046] 11-initial tube blank; 12-variable tube blank; 121-variable area; 122-straight tube area; 13-double-convex tube blank; 131-convex part; 14-target tube; 141-branch tube; 2-axial hydraulic filling die; 21-first upper die; 22-first lower die; 23-support spring; 24-upper sealing punch; 25-lower sealing punch; 26-limiting bolt; 27-first sealing ring; 28-first fluid inlet; 29-cavity; 3-circumferential hydraulic filling die; 31- The second upper die; 32-the second lower die; 33-the left sealing punch; 34-the right sealing punch; 35-the second fluid inlet; 36-the second sealing ring; 37-the internal support; 38-the groove structure; 4-the mold clamping system; 41-the displacement sensor; 42-the displacement drive structure; 43-the motor; 5-the liquid filling and pressurizing system; 51-the electromagnetic reversing valve; 52-the overflow valve; 53-the oil tank; 54-the hydraulic pump; 55-the supercharger; 56-the pressure sensor; 6-the control system. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0048] It should be noted that in the description of the present invention, the directions or positional relationships indicated by “up”, “down”, “left”, “right”, “top”, “bottom”, “front”, “back”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, it should not be understood as limiting the scope of protection of the present invention.

[0049] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0050] Moreover, although the present invention is described with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be designed without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the features of the various dependent claims and herein may be combined in a manner not described in the original claims. It may also be understood that the features described in conjunction with the individual embodiments may be used in other embodiments.

[0051] To solve the above problems, Figure 1 and Figures 3 to 9 As shown, the present invention provides a multi-directional hydraulic forming method for a four-way pipe fitting, comprising the following steps:

[0052] S1, determining the diameter of the initial tube blank 11 and the size of the diameter-reducing zone 121 of the diameter-reducing tube blank 12 according to the size of the target tube 14;

[0053] S2, calculating the internal pressure p1 and the axial reduction amount Δl required for pressing the initial tube blank 11 into the reduced diameter tube blank 12, and the supporting internal pressure p2 required for pressing the reduced diameter tube blank 12 into the double-convex tube blank 13;

[0054] S3, determining the length of the initial tube blank 11 according to the axial reduction amount Δl and the target tube 14 length;

[0055] S4, preparing the initial tube blank 11;

[0056] S5, placing the initial tube blank 11 into the axial hydraulic pressure forming die 2, and performing axial pressing according to the internal pressure p1 and the axial pressing amount Δl to obtain the reduced diameter tube blank 12;

[0057] S6, placing the reduced diameter tube blank 12 into the annular hydraulic pressure forming die 3, and performing annular pressing according to the support internal pressure p2 to obtain a double-convex tube blank 13;

[0058] S8, removing the end of the raised portion 131 of the double-raised tube blank 13 to obtain the target tube 14.

[0059] In this embodiment, preliminary preparations are first performed. First, the diameter of the initial tube blank 11 used for forming and the size of the variable diameter region 121 of the reduced diameter tube blank 12 formed by the initial tube blank 11 through the axial hydraulic filling die 2 are determined according to the size of the target tube 14 to be obtained. Then, the internal pressure p1 and the axial reduction amount Δl required for the initial tube blank 11 to be pressed into the reduced diameter tube blank 12 in the axial hydraulic filling die 2 and the parameters of the initial tube blank 11 are calculated, as well as the supporting internal pressure p2 required for the reduced diameter tube blank 12 to be pressed into the double-convex tube blank 13 in the annular hydraulic filling die 3. Finally, the length of the initial tube blank 11 is calculated by the axial reduction amount Δl and the length of the target tube 14. The initial tube blank 11 is prepared according to the length and diameter of the initial tube blank 11, and the preparation work is completed. The initial tube blank 11 is placed in the axial hydraulic filling die 2, and axial pressing is performed according to the internal pressure p1 and the axial pressing amount Δl to obtain a reduced diameter tube blank 12. The internal pressure can ensure that the initial tube blank 11 is always supported outwards in the process of being pressed and shortened, so as to prevent the initial tube blank 11 from being concave inwards during pressing; the obtained reduced diameter tube blank 12 is then placed in the annular hydraulic filling die 3, and annular pressing is performed according to the support internal pressure p2 to obtain a double-convex tube blank 13. The support internal pressure can ensure that the reduced diameter tube blank 12 is always supported outwards in the process of being pressed, so as to prevent the reduced diameter tube blank 12 from being concave inwards during pressing. The convex part of the double-convex tube blank 13 is concave inward, and the convex part is the branch tube 141 of the target tube 14. The top of the convex part 131 of the double-convex tube blank 13 is removed to obtain the target tube 14, that is, the four-way pipe fitting. The present invention first axially presses the initial tube blank 11 to shorten the length of the initial tube blank 11. The shortened part protrudes circumferentially in the middle of the initial tube blank 11 to form a reduced diameter tube blank 12. The protruding part is the reduced diameter area 121 of the reduced diameter tube blank 12. The reduced diameter area 121 is an annular area, and its two ends are straight tube areas 122. Subsequently, the annular hydraulic pressing die 3 presses the reduced diameter area 121 to press the circumferentially surrounding reduced diameter area 121 to the position of the two branch tubes 141 of the target tube 14. The variable diameter area 121 is transformed into two raised parts 131 of the double-raised tube blank 13, and finally the ends of the two raised parts 131 are removed to connect the raised parts 131 with the outside to form a branch pipe 141, and a four-way pipe fitting is obtained. In this process, the material used to form the branch pipe 141 comes from the circumferential protrusions formed during the axial pressing of the initial tube blank 11, which can ensure that the material used to form the branch pipe 141 is sufficient, avoid the thinning and cracking of the branch pipe 141 and the connecting area, improve the overall structural integrity of the four-way pipe fitting, and solve the problem of difficult material filling and easy cracking defects in the middle deformation zone of the internal high-pressure formed four-way pipe fitting, and the obtained four-way pipe fitting has uniform wall thickness, complete structure and excellent performance.

[0060] Specifically, compared with the existing internal high pressure forming method, the internal pressure of the present application is generally lower than the yield internal pressure of the pipe during liquid filling forming, and only plays a supporting role. In addition, the forming pressure required by the present application is low, and the tonnage of the mold pressing equipment required is small. It is suitable for the overall forming of high-strength and large thickness-diameter ratio four-way pipe fittings such as high-temperature alloys and stainless steels, such as high-temperature alloys, martensitic heat-resistant stainless steel, titanium alloys, etc. The diameter of the four-way pipe fittings is usually less than 20 mm; the angle between the two branches 141 is 120~180°.

[0061] Optionally, in step S1, the diameter of the initial tube blank 11 is equal to the diameter of the straight tube area 122 of the target tube 14, the circumference of the variable diameter area 121 of the variable diameter tube blank 12 is equal to the circumference of the axial cross-section at the branch tube 141 of the target tube 14, and the length of the variable diameter area 121 is ≤ the diameter of the branch tube 141 of the target tube 14.

[0062] In this embodiment, the diameter of the initial tube blank 11 is set to the diameter of the target tube 14. In this way, only the branch tube 141 needs to be processed without changing the diameter of the initial tube blank 11. The outer contour circumference of the reducer area is set to the circumference of the outer contour of the axial section at the branch tube 141 of the target tube 14, that is, Fig. 9 The circumference of the middle structure ensures that the cross-sectional circumferences of the variable diameter zone 121 of the variable diameter tube blank 12 and the branch tube 141 of the target tube 14 at the same axial position are equal. The circumference of the variable diameter zone 121 can be calculated based on the diameter of the variable diameter zone 121. The length of the variable diameter zone 121 is set to be less than or equal to the length of the branch tube 141 of the target tube 14 to prevent the volume of the variable diameter zone 121 from being too large to fit into the annular hydraulic filling forming mold 3.

[0063] Optionally, in step S2, p s ≤p1≤2p s , p2≤p s , where p s is the yield pressure of the initial tube blank 11;

[0064]

[0065] Wherein V is the volume of the variable diameter zone 121 of the variable diameter tube blank 12, η ​​is the average thinning rate, 0≤η≤5%, d0 is the diameter of the initial tube blank 11, t is the wall thickness of the initial tube blank 11, and l0 is the length of the variable diameter zone 121.

[0066] In this embodiment, the following formula is used:

[0067] p s ≤p1≤2p s , p2≤p s ,and

[0068] The specific values ​​of the calculated internal pressure p1, support internal pressure p2, and axial reduction Δl, wherein V is the volume of the variable diameter zone 121 of the variable diameter tube blank 12, which can be obtained according to the length and diameter of the variable diameter tube blank 12, η ​​is the average thinning rate, 0≤η≤5%, d0 is the diameter of the initial tube blank 11, t is the wall thickness of the initial tube blank 11, l0 is the length of the variable diameter zone 121, p s is the yield pressure of the initial tube blank 11, and the values ​​of the internal pressure p1, the support internal pressure p2, and the axial reduction amount Δl may be any as long as they are within the range of the calculation results.

[0069] Yield pressure of initial tube 11 where σ s is the initial yield strength of the initial tube blank 11.

[0070] Optionally, in step S3, the length of the initial tube blank 11 = the length of the target tube 14 + Δl.

[0071] In this embodiment, the length of the initial tube blank 11 is calculated to be equal to the length of the target tube 14 plus the axial reduction amount Δl, and the axial reduction amount Δl is the shortened length of the target tube 14. In this way, the length of the processed cross-way pipe fitting is the target length.

[0072] Specifically, the size of the target tube 14 is set to be 120 mm in length, 14 mm in diameter in the straight tube area 122, 1.2 mm in wall thickness, and 10 mm in diameter in the branch tube 141; according to the above size, the diameter of the variable diameter area 121 of the variable diameter tube blank 12 can be set to 21 mm, the length l0 can be set to 13 mm, the diameter d0 of the initial tube blank 11 can be set to 14 mm, the wall thickness t can be set to 1.2 mm, and the initial yield strength can be set to σ s =400MPa; the initial yield pressure of the initial tube blank 11 is calculated to be p s =69MPa, axial reduction Δl=5.2mm, from which it can be seen that the range of internal pressure p1 is 69-138MPa, the range of support internal pressure p2 is 0-69MPa, and finally the internal pressure is 100MPa, the support internal pressure is 69MPa, and the length of the initial tube blank 11 is 125.2mm.

[0073] Alternatively, if Figure 2 As shown, between step S6 and step S8, it also includes:

[0074] S7, annealing the double-convex tube blank 13.

[0075] In this embodiment, by annealing the double-protrusion tube blank 13, residual stress can be eliminated, plasticity can be restored, and deformation and cracking can be avoided.

[0076] Optionally, removing the end of the raised portion 131 of the double-raised tube blank 13 includes:

[0077] The two protruding ends of the double-protruding tube blank 13 are cut and flanging is performed.

[0078] In this embodiment, the end of the double-protrusion tube blank 13 is cut and flanging is performed to obtain a branch pipe 141 connected to the outside, and the connection performance of the end of the branch pipe 141 is improved.

[0079] Specifically, laser cutting can be used to cut holes in the raised portion 131 of the double-raised tube blank 13, and the raised portion can be flanging by punching or drawing holes, so as to finally obtain a four-way pipe fitting.

[0080] Another embodiment of the present invention provides a multi-directional hydraulic filling forming device for a four-way pipe fitting, which is used to implement the above-mentioned multi-directional hydraulic filling forming method for a four-way pipe fitting. The multi-directional hydraulic filling forming device for a four-way pipe fitting includes an axial hydraulic filling forming die 2 and an annular hydraulic filling forming die 3.

[0081] Compared with the prior art, the beneficial effects of the multi-directional hydraulic filling forming device for a four-way pipe fitting of this embodiment are substantially the same as the beneficial effects of the multi-directional hydraulic filling forming method for a four-way pipe fitting described above, and will not be described in detail herein.

[0082] Specifically, the multi-directional hydraulic filling forming device for the four-way pipe fitting includes an axial hydraulic filling forming device for the four-way pipe fitting and an annular hydraulic filling forming device for the four-way pipe fitting. The axial hydraulic filling forming device for the four-way pipe fitting includes an axial hydraulic filling forming mold 2, and the annular hydraulic filling forming device for the four-way pipe fitting includes an annular hydraulic filling forming mold 3.

[0083] Alternatively, if Fig.10 and 11 As shown, the axial liquid filling forming mold 2 includes a first upper mold 21, a first lower mold 22, a support spring 23, an upper sealing punch 24, a lower sealing punch 25 and a limiting bolt 26. The first upper mold 21 and the first lower mold 22 are respectively provided with a cavity 29 that penetrates the first upper mold 21 and the first lower mold 22 in the vertical direction. The two cavities 29 are used to communicate to form a first mold cavity. The first upper mold 21 is provided with a countersunk hole, and the first lower mold 22 is provided with a threaded hole. The limiting bolt 26 passes through the first upper mold 21 and the first lower mold 22. The countersunk hole is threadedly connected to the threaded hole, the first upper die 21 is slidably connected to the limit bolt 26, the shape of the first die cavity matches the shape of the reduced diameter tube blank 12, the initial tube blank 11 is used to be arranged in the first die cavity, the upper sealing punch 24 and the lower sealing punch 25 are used to seal the two ends of the initial tube blank 11, and are used to drive the first upper die 21 and the first lower die 22 to move toward each other, and a first fluid inlet 28 is provided on the upper sealing punch 24 or the lower sealing punch 25.

[0084] In this embodiment, the first upper mold 21 and the first lower mold 22 are arranged up and down in the Z-axis direction, and a cavity 29 extending along the Z-axis direction is opened on the first upper mold 21 and the first lower mold 22, and an upper sealing punch 24 is connected to the upper side of the first upper mold 21, and a lower sealing punch 25 is connected to the lower side of the first lower mold 22. The upper sealing punch 24 and the lower sealing punch 25 can move toward each other, and the first upper mold 21 and the first lower mold 22 are pressed together, and the two cavities 29 are connected, and the two cavities 29 are closed to form The first mold cavity has a shape corresponding to the shape of the variable diameter tube blank 12. The first upper mold 21 is provided with a countersunk hole extending in the Z-axis direction. The upper surface of the first lower mold 22 is provided with a threaded hole extending in the Z-axis direction. The screw end of the limit bolt 26 is passed through the countersunk hole from the upper side of the countersunk hole and screwed into the threaded hole to fix the limit bolt 26 on the first lower mold 22. The first upper mold 21 can slide along the screw of the limit bolt 26. The limit bolt 26 is located between the first upper mold 21 and the first lower mold. The support spring 23 is sleeved on the part between the upper and lower dies 21 and the lower dies 22. The limit bolt 26 specifies the expansion and contraction direction of the support spring 23 to prevent the support spring 23 from deflecting when expanding and contracting. The nut of the limit bolt 26 can be completely embedded in the countersunk hole. That is, when the first upper die 21 slides along the screw of the limit bolt 26 within the set range, the sliding distance, that is, the distance between the first upper die 21 and the first lower die 22 is equal to the axial pressing amount Δl. The limit screw can be set to adjust the distance between the first upper die 21 and the first lower die 22 according to different axial pressing amounts Δl. The nut of the limit bolt 26 will not extend out of the countersunk hole, so that the first upper die 21 and the first lower die 22 can always interact with each other through elastic force within a certain spacing range. When pressing is required, the initial tube blank 11 is first placed in the cavity 29 of the first upper die 21 and the first lower die 22, and the upper sealing punch 24 and the lower sealing punch 25 are connected to the upper and lower sides of the first upper die 21 and the first lower die 22, and the initial tube blank 11 is sealed. Fig.10 As shown, at this time, the liquid is passed into the initial tube blank 11 through the first fluid inlet 28 opened on the upper sealing punch 24 or the lower sealing punch 25 until the internal pressure p1 is reached, and then the upper sealing punch 24 and the lower sealing punch 25 are driven to move toward each other, the first upper die 21 and the first lower die 22 are pressed together, and the two cavities 29 are connected and closed. The initial tube blank 11 is pressed into a reduced diameter tube blank 12 according to the shape of the cavity 29, as shown in FIG. Fig.11 As shown, after the pressing is completed, the support spring 23 facilitates the first upper mold 21 and the second upper mold 31 to be reset after the pressing is completed.

[0085] Specifically, a first sealing ring 27 is disposed between the upper sealing punch 24, the lower sealing punch 25 and the initial tube blank 11 to ensure sealing and facilitate filling the initial tube blank 11 with liquid so that the pressure inside the initial tube blank 11 reaches the internal pressure p1.

[0086] Alternatively, if Figures 12 to 15 As shown, the annular hydraulic filling forming mold 3 includes a second upper mold 31, a second lower mold 32, a left sealing punch 33 and a right sealing punch 34. The lower surface of the second upper mold 31 and the upper surface of the second lower mold 32 are respectively provided with groove structures 38 that penetrate the second upper mold 31 and the second lower mold 32 in the horizontal direction. The second upper mold 31 and the second lower mold 32 are used to move towards each other. The two groove structures 38 are used to enclose a second mold cavity. The shape of the second mold cavity matches the shape of the double-convex tube blank 13. The reduced diameter tube blank 12 is used to be arranged in the second mold cavity. The left sealing punch 33 and the right sealing punch 34 are used to seal the two ends of the reduced diameter tube blank 12. A second fluid inlet 35 is provided on the left sealing punch 33 or the right sealing punch 34.

[0087] In this embodiment, a second upper die 31 and a second lower die 32 are arranged up and down in the Z-axis direction, and a groove structure 38 extending and penetrating along the X-axis direction is provided on the lower surface of the second upper die 31 and the upper surface of the second lower die 32. When the two groove structures 38 are closed, a second mold cavity is formed. The shape of the second mold cavity corresponds to the shape of the double-convex tube blank 13. When pressing, the reduced diameter tube blank 12 is first placed between the two groove structures 38, and the left sealing punch 33 and the right sealing punch 34 are sealed and connected at both ends of the groove structure 38, and the reduced diameter tube blank 12 is blocked. The reduced diameter tube blank 12 is filled with liquid through the second fluid inlet 35 on the left sealing punch 33 or the right sealing punch 34 until the pressure reaches the supporting internal pressure p2, as shown in FIG. Fig.12 and Fig.13 As shown, the second upper die 31 and the second lower die 32 are driven to move toward each other, and the second upper die 31 and the second lower die 32 are pressed together, and the two groove structures 38 are connected and closed, and the reduced diameter tube blank 12 is pressed into a double-convex tube blank 13 according to the shape of the groove structure 38, as shown in FIG. Fig.14 and Fig.15 shown.

[0088] Specifically, a second sealing ring 36 is arranged between the left sealing punch 33, the right sealing punch 34 and the reducer tube blank 12 to ensure sealing and facilitate filling liquid into the reducer tube blank 12 so that the pressure inside the reducer tube blank 12 reaches the support internal pressure p2. During the annular liquid filling and pressing process, an internal support 37 can be arranged inside the variable diameter area 121 of the reducer tube blank 12 to prevent the occurrence of concave phenomenon during the pressing process. The internal support 37 structure can be a support frame, and the support frame can be a rigid structure or an elastic structure.

[0089] Alternatively, if Fig.16 and Fig.17As shown, the multi-directional hydraulic filling forming device for four-way pipe fittings also includes a mold closing and pressing system 4 and a liquid filling and pressurizing system 5. The mold closing and pressing system 4 is used to press the axial hydraulic filling forming mold 2 or the annular hydraulic filling forming mold 3, and the liquid filling and pressurizing system 5 is used to fill the mold cavity of the axial hydraulic filling forming mold 2 or the annular hydraulic filling forming mold 3 with liquid.

[0090] In this embodiment, a mold closing and pressing system 4 is provided to respectively drive the upper sealing punch 24 and the lower sealing punch 25, the second upper mold 31 and the second lower mold 32 to move toward each other, so as to facilitate pressing. A liquid filling and pressurizing system 5 is provided to respectively fill the initial tube blank 11 located in the first mold cavity and the reduced diameter tube blank 12 located in the second mold cavity with liquid, so as to facilitate the pressure inside the initial tube blank 11 and the reduced diameter tube blank 12 to meet the standard.

[0091] Specifically, the mold clamping system 4 includes a displacement sensor 41, a displacement drive structure 42 and a motor 43. The displacement drive structure 42 can be a ball screw or a telescopic rod. The motor 43 drives the displacement drive structure 42. The displacement drive structure 42 is connected to the upper sealing punch 24 to drive the upper sealing punch 24 to move to the lower sealing punch 25. The lower sealing punch 25 can be fixed on the workbench; another set of displacement drive structure 42 and motor 43 are connected to the second upper mold 31, and the second lower mold 32 is fixed on the workbench to facilitate the second upper mold 31 and the first lower mold 32 to move. The two lower molds 32 are pressed together, and the displacement drive structure 42 is also provided with a displacement sensor 41 to facilitate the detection of the moving distance; the liquid filling and pressurizing system 5 includes an electromagnetic reversing valve 51, a relief valve 52, an oil tank 53, a hydraulic pump 54, a supercharger 55 and a pressure sensor 56. The hydraulic pump 54 draws hydraulic oil through the electromagnetic reversing valve 51 and the supercharger 55 to fill the initial tube blank 11 or the reduced diameter tube blank 12, the electromagnetic reversing valve 51 switches to relieve pressure, the relief valve 52 protects the oil circuit to prevent excessive pressure in the oil circuit, and the pressure sensor 56 detects the pressure value.

[0092] The multi-directional hydraulic filling forming device for four-way pipe fittings also includes a control system 6, which is electrically connected to the displacement sensor 41 and the pressure sensor 56, and can obtain data on the axial pressure Δl, the internal pressure p1, and the support internal pressure p2 in real time, and control the internal pressure p1, the support internal pressure p2, and the axial pressure Δl in real time through the electromagnetic reversing valve 51 and the motor 43.

[0093] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A multi-directional hydraulic forming method for a four-way pipe fitting, characterized in that: The steps include: S1. Determine the diameter of the initial tube blank (11) and the size of the diameter-reducing zone (121) of the diameter-reducing tube blank (12) according to the size of the target tube (14); S2, calculating the internal pressure p1 and the axial reduction amount Δl required for pressing the initial tube blank (11) into the reduced diameter tube blank (12), and the supporting internal pressure p2 required for pressing the reduced diameter tube blank (12) into the double-convex tube blank (13); S3, determining the length of the initial tube blank (11) according to the axial reduction amount Δl and the target tube (14) length; S4, preparing the initial tube blank (11); S5, placing the initial tube blank (11) into an axially hydraulically filled forming die (2), and performing axial pressing according to the internal pressure p1 and the axial pressing amount Δl, to obtain the reduced diameter tube blank (12); S6, placing the reduced diameter tube blank (12) into the annular hydraulic pressure forming die (3), and performing annular pressing according to the support internal pressure p2 to obtain a double-convex tube blank (13); S8. Remove the end of the raised portion (131) of the double-raised tube blank (13) to obtain the target tube (14).

2. The multi-directional hydraulic forming method for a four-way pipe fitting according to claim 1, characterized in that: In step S1, the diameter of the initial tube blank (11) is equal to the diameter of the straight tube area (122) of the target tube (14), the circumference of the diameter-reducing area (121) of the diameter-reducing tube blank (12) is equal to the circumference of the axial cross section at the branch tube (141) of the target tube (14), and the length of the diameter-reducing area (121) is less than or equal to the diameter of the branch tube (141) of the target tube (14).

3. The multi-directional hydraulic forming method for a four-way pipe fitting according to claim 1, characterized in that: In step S2, p s ≤p1≤2p s , p2≤p s , where p s is the yield pressure of the initial tube blank (11); Wherein V is the volume of the variable diameter zone (121) of the variable diameter tube blank (12), η is the average thinning rate, 0≤η≤5%, d0 is the diameter of the initial tube blank (11), t is the wall thickness of the initial tube blank (11), and l0 is the length of the variable diameter zone (121).

4. The multi-directional hydraulic forming method for a four-way pipe fitting according to claim 1, characterized in that: In step S3, the length of the initial tube blank (11) = the length of the target tube (14) + Δl.

5. The multi-directional hydraulic forming method for a four-way pipe fitting according to claim 1, characterized in that: Also included between step S6 and step S8: S7, annealing the double-convex tube blank (13).

6. The multi-directional hydraulic forming method for a four-way pipe fitting according to claim 1, characterized in that: The step of removing the end of the raised portion (131) of the double-raised tube blank (13) comprises: The two protruding ends of the double-protruding tube blank (13) are cut with holes and flanging is performed.

7. A multi-directional hydraulic forming device for a four-way pipe fitting, characterized in that: The method for multi-directional hydraulic filling forming of a four-way pipe fitting according to any one of claims 1 to 6 is used to implement the multi-directional hydraulic filling forming device of a four-way pipe fitting, wherein the multi-directional hydraulic filling forming device comprises an axial hydraulic filling forming die (2) and an annular hydraulic filling forming die (3).

8. The multi-directional hydraulic forming device for a cross-way pipe fitting according to claim 7, characterized in that: The axially-filled hydraulic die (2) comprises a first upper die (21), a first lower die (22), a support spring (23), an upper sealing punch (24), a lower sealing punch (25) and a limiting bolt (26); the first upper die (21) and the first lower die (22) are respectively provided with a cavity (29) penetrating the first upper die (21) and the first lower die (22) in a vertical direction; the two cavities (29) are used to be connected to form a first die cavity; the first upper die (21) is provided with a countersunk hole; the first lower die (22) is provided with a threaded hole; the limiting bolt (26) The first upper die (21) is slidably connected to the limit bolt (26) through the countersunk hole and is threadedly connected to the threaded hole. The shape of the first die cavity matches the shape of the reduced diameter tube blank (12). The initial tube blank (11) is used to be arranged in the first die cavity. The upper sealing punch (24) and the lower sealing punch (25) are used to seal the two ends of the initial tube blank (11) and to drive the first upper die (21) and the first lower die (22) to move toward each other. A first fluid inlet (28) is provided on the upper sealing punch (24) or the lower sealing punch (25).

9. The multi-directional hydraulic forming device for a four-way pipe fitting according to claim 7, characterized in that: The annular hydraulic filling die (3) comprises a second upper die (31), a second lower die (32), a left sealing punch (33) and a right sealing punch (34); the lower surface of the second upper die (31) and the upper surface of the second lower die (32) are respectively provided with a groove structure (38) which passes through the second upper die (31) and the second lower die (32) in a horizontal direction; the second upper die (31) and the second lower die (32) are used to move towards each other; the two groove structures (38) are used to enclose a second die cavity; the shape of the second die cavity matches the shape of the double-convex tube blank (13); the reduced diameter tube blank (12) is used to be arranged in the second die cavity; the left sealing punch (33) and the right sealing punch (34) are used to seal the two ends of the reduced diameter tube blank (12); a second fluid inlet (35) is provided on the left sealing punch (33) or the right sealing punch (34).

10. The multi-directional hydraulic forming device for a four-way pipe fitting according to claim 7, characterized in that: It also includes a mold closing and pressing system (4) and a liquid filling and pressurizing system (5), wherein the mold closing and pressing system (4) is used to press the axial liquid filling molding die (2) or the annular liquid filling molding die (3), and the liquid filling and pressurizing system (5) is used to fill liquid into the mold cavity of the axial liquid filling molding die (2) or the mold cavity of the annular liquid filling molding die (3).

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