Manufacturing process of inclined tee joint and forming device used by manufacturing process

Abstract

The invention belongs to the technical field of inclined tee joint manufacturing, and particularly relates to a manufacturing process of an inclined tee joint and a forming device used by the manufacturing process. By controlling the selection of the raw materials and accurately calculating the blanking length, the utilization rate of the raw materials is increased, the cost is saved, and the production efficiency is further improved. The solid medium adopted by the invention can be self-sealed in the forming process, and the maximum forming internal pressure can reach 600MPa. And the solid medium is added for filling, so that the forming pressure requirement of the inclined tee joint made of high-strength and corrosion-resistant materials can be met. By designing the forming device which is made of a high-strength and corrosion-resistant material and is unique in structure, the steel pipe is subjected to cold extrusion forming and heat treatment, so that the high-strength, corrosion-resistant and integrally-formed inclined tee joint is manufactured, the inclined tee joint is suitable for most pipeline systems under special working conditions in the fields of petroleum, chemical engineering and the like in the future, the practicability of the inclined tee joint is further improved, and the application range is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of manufacturing oblique tees, and in particular relates to a manufacturing process of an oblique tee and a molding device used therein. Background Art

[0002] Tee, also known as pipe tee or tee pipe fitting, tee joint, etc., is mainly used to change the direction of the fluid. It has three interfaces and the overall shape is similar to "T" or "Y". These three interfaces can connect one pipe to the other two pipes. It is generally made of carbon steel, alloy steel, stainless steel, nickel-based alloy, copper or aluminum alloy. The oblique tee is a type of tee, and the angle between its branch pipe and the main pipe can be 30°, 45°, 60° or any other angle.

[0003] At present, the inclined tee pipe fittings are generally manufactured by welding, that is, a saddle mouth is opened at the intersection of the main pipe and the branch pipe, one end of the branch pipe is also cut into a shape similar to the saddle mouth of the main pipe, and then the branch pipe and the saddle mouth of the main pipe are butted and welded together. The inclined tee pipe fittings manufactured by this method have stress concentration at the intersection, especially the fillet weld formed by welding, which causes impact and gasping when the fluid flows through this part. These are not conducive to the safe use of the inclined tee pipe fittings and also increase the fluid resistance.

[0004] Patent CN118218429A discloses a cold extrusion forming method for an oblique tee, but the forming method is to cut a seamless straight pipe according to the required cutting length, then put it into a mold, apply pressure, and inject high-pressure water into the seamless straight pipe to finally obtain an oblique tee blank. This forming method is only applicable to general carbon steel, alloy steel, stainless steel and other materials, and is difficult to apply to high-strength, corrosion-resistant steel materials. Moreover, the formed products prepared by this forming method are only applicable to pipelines under ordinary working conditions, which has great limitations.

[0005] Therefore, a new manufacturing process of an oblique tee and an available forming device are badly needed. Summary of the invention

[0006] The present invention aims to overcome the defects that the manufacturing process of the oblique tee in the prior art is difficult to apply to high-strength, corrosion-resistant steel materials, and the prepared molded products are only suitable for pipelines under ordinary working conditions, which has great limitations. A manufacturing process of an oblique tee and a molding device used therein are provided.

[0007] To achieve the above-mentioned purpose, the present invention is implemented by the following technical solutions: A manufacturing process of an oblique tee, comprising the following steps: (S.1) Selection of raw materials: A steel pipe is selected as the raw material, the outer diameter of the steel pipe is the same as the outer diameter of the main pipe of the oblique tee, and the wall thickness of the steel pipe is 1.2 to 2.5 times the nominal wall thickness of the main pipe of the oblique tee; the cutting length of the steel pipe is calculated according to the following formula; Cutting length = A + B + C * X; In the formula, A represents the length from the center of the main pipe of the inclined tee to the end face of the main pipe close to the center of the main pipe, B represents the length from the center of the main pipe of the inclined tee to the end face of the main pipe far from the center of the main pipe, C represents the length from the center of the main pipe of the inclined tee to the end face of the branch pipe, X represents the proportional coefficient corresponding to the outer diameter of the main pipe of the inclined tee, and X is 1.0 to 2.0; (S.2) Cold extrusion molding: Cut the steel pipe according to the blanking length and fill the blanked steel pipe with a solid medium, wherein the solid medium includes clay, graphite and lubricating oil, and the mass ratio of clay, graphite and lubricating oil in the solid medium is 10-20:1-5:0.2-0.5, and then put it into a mold in a molding device, lock the mold, and use a punch to perform multiple cold extrusions on the main pipe end of the oblique tee, and mold in batches to obtain an oblique tee blank; (S.3) Heat treatment: The oblique tee blank obtained in step (S.2) is heat treated and water-cooled to obtain the oblique tee, which is then pickled, machined, and inspected.

[0008] The manufacturing process of the oblique tee of the present invention helps to improve the utilization rate of raw materials, save costs, and further improve production efficiency by controlling the selection of raw materials and accurately calculating the cutting length. The molding process of the oblique tee of the present invention uses a solid medium that can be self-sealed during the molding process, and the maximum molding internal pressure can reach 600MPa. The traditional liquid medium is limited by the sealing gasket, and the maximum molding internal pressure cannot exceed 200MPa. Adding solid medium for filling helps to meet the molding pressure requirements of high-strength, corrosion-resistant material oblique tees. Furthermore, the inventors of the present invention have found through many production practices that a low proportion of clay added to the solid medium or a high proportion of lubricating oil added can easily lead to a softer medium during the molding process, and a higher molding internal pressure cannot be provided. A high proportion of clay added will lead to excessive molding internal pressure, which further causes the steel pipe to be overstressed, causing the oblique tee branch pipe to rupture or damage the mold. The present invention designs a forming device of high-strength and corrosion-resistant material with a unique structure, performs cold extrusion forming and heat treatment on the steel pipe, thereby producing a high-strength, corrosion-resistant, integrated oblique tee. In the future, it will be suitable for use in pipeline systems under special working conditions in most petroleum, chemical and other fields, further improving its practicality and widening its scope of application.

[0009] Preferably, the material of the steel pipe is any one of duplex steel S31803, duplex steel S32205, duplex steel S32750, duplex steel S32760, nickel-based alloy N04400, nickel-based alloy N06600, nickel-based alloy N06625, nickel-based alloy N08800, nickel-based alloy N08825, nickel-based alloy N08810, and nickel-based alloy N08020.

[0010] The above-mentioned duplex steel or nickel-based alloy has high strength, good toughness, excellent corrosion resistance, and good processability and weldability. The selection of duplex steel or nickel-based alloy as the material of the steel pipe helps to maintain its stable performance and material integrity under extreme environments such as high temperature, high pressure, and strong corrosion, thereby extending its service life and further reducing maintenance costs, so that it can be widely used in aerospace, energy, marine engineering, chemical industry and other fields.

[0011] Preferably, in the step (S.2), the second cold extrusion molding amount in the two adjacent cold extrusion molding processes is 10 to 60% of the first cold extrusion molding amount; and stress relief heat treatment is also required between the two adjacent cold extrusion molding processes.

[0012] Preferably, the internal molding pressure formed during the solid medium filling in step (S.2) is 30 to 600 MPa.

[0013] The internal pressure of the solid medium during solid medium filling is calculated based on the outer diameter, wall thickness and material of the steel pipe. When the internal pressure is less than 30MPa, it cannot meet the molding requirements. The surface of the oblique tee is prone to depression after extrusion, and the size is difficult to meet the requirements. When the internal pressure is greater than 600MPa, the oblique tee branch pipe may rupture or even damage the mold due to excessive internal pressure.

[0014] Preferably, when the material of the steel pipe is dual-phase steel, the heating temperature for heat treatment of the oblique tee blank in step (S.3) is 1020-1140°C; when the material of the steel pipe is nickel-based alloy, the heating temperature for heat treatment of the oblique tee blank in step (S.3) is 900-1180°C.

[0015] Preferably, the holding time after heat treatment of the oblique tee blank in step (S.3) is calculated according to the following formula: H=(0.5~2)min / mm*t+(158-0.125T); Wherein, H represents the holding time of heat treatment; t represents the maximum wall thickness of the steel pipe; min represents minutes; mm represents millimeters; T represents the reaction temperature of heat treatment, in °C.

[0016] A molding device used in the manufacturing process of the oblique tee as described above comprises: A half-mold assembly, comprising a first half-mold and a second half-mold, wherein a mold cavity for molding a product shape is disposed in the first half-mold and the second half-mold, guide blocks for guiding when the molds are closed are disposed on the longitudinal section of the first half-mold and on both sides of the mold cavity, grooves matching the guide blocks are disposed on the longitudinal section of the second half-mold and on both sides of the mold cavity, and a plurality of positioning bolt holes are disposed on the outer side walls of the first half-mold and the second half-mold; A mold locking mechanism, which is sleeved on the outside of the half mold assembly and is used to lock the half mold assembly; A punch is used to perform cold extrusion on a product, and the punch includes an upper punch and a lower punch, wherein the lower end of the upper punch is inserted into the die cavity, and the upper end of the upper punch protrudes upward in a direction away from the top of the half-die assembly, and the upper end of the lower punch is inserted into the die cavity, and the lower end of the lower punch protrudes downward in a direction away from the bottom of the half-die assembly.

[0017] The forming device used in the manufacturing process of the oblique tee of the present invention includes a half mold assembly. The half mold assembly includes a first half mold and a second half mold, and a mold cavity for forming the shape of the product is provided in the first half mold and the second half mold. Guide blocks for guiding when closing the mold are provided on the longitudinal section of the first half mold and on both sides of the mold cavity. Grooves adapted to the guide blocks are provided on the longitudinal section of the second half mold and on both sides of the mold cavity. A plurality of positioning bolt holes are provided on the outer side walls of the first half mold and the second half mold. The forming device of the present invention also includes a locking mechanism sleeved on the outer side of the half mold assembly and used to lock the half mold assembly. The forming device of the present invention also includes a punch for cold extrusion of the product. The punch includes an upper punch and a lower punch. The lower end of the upper punch is inserted into the mold cavity, and the upper end of the upper punch protrudes upward in a direction away from the top of the half mold assembly. The upper end of the lower punch is inserted into the mold cavity, and the lower end of the lower punch protrudes downward in a direction away from the bottom of the half mold assembly.

[0018] At present, most of the oblique tees in the stainless steel field are produced by welding or forging, but they cannot achieve a smooth transition of the inner wall to ensure the fluidity of the medium. The oblique tees produced by welding are difficult to assemble the main pipe and the branch pipe, and the welding position is special. Automatic welding and other methods cannot be used. After welding, welding quality problems are also prone to occur. The forged oblique tees use round steel to forge square forging billets, and then boring and machining. The disadvantages of this method are low material utilization and high manufacturing costs.

[0019] Unlike traditional oblique tees, which are prone to fatigue cracking due to variable stress on the weld, the oblique tee of the present invention has the characteristics of integrated molding and outstanding load-bearing capacity. The molding device used in the manufacturing process of the oblique tee of the present invention selects high-hardness pre-hardened steel (made of 40Cr, pre-hardened steel with HRC52-56 nitrided after quenching and tempering), which helps to ensure the service life and production efficiency of the molding device. In addition, the present invention restores the product size structure 1:1 based on the small-diameter oblique tee size of SH / T 3408, simulates the material flowability from the design of the molding device, and thus ensures the integrated molding of the product.

[0020] Preferably, the cross-sectional shape of the first half mold and the second half mold are both semicircular; the cross-sectional shape of the punch is rectangular; and the cross-sectional shape of the clamping mechanism is circular.

[0021] Preferably, the number of the guide blocks is at least four.

[0022] By setting the guide block and plugging it into the groove, it helps to improve the mold closing accuracy, thereby improving the molding accuracy and consistency of the product. At the same time, the mutual cooperation between the guide block and the groove not only provides guidance for the mold closing process, but also plays a supporting role after the mold closing, enhancing the overall stability of the mold. In addition, the smooth cooperation between the guide block and the groove can achieve rapid mold closing, further improving production efficiency.

[0023] Preferably, the number of the positioning bolt holes is at least four.

[0024] The positioning bolt holes are provided to help the first and second mold halves to be accurately aligned and fastened during the mold closing process, thereby preventing displacement or misalignment during the molding process, thereby ensuring accurate mold closing. At the same time, the design of the positioning bolt holes makes the mold installation and disassembly process simpler and faster, thereby improving work efficiency and facilitating mold transportation.

[0025] Preferably, an upper template is arranged above the upper punch, and the upper template is detachably connected to the outer side wall of the clamping mechanism, and a lower template is arranged below the lower punch.

[0026] Preferably, the upper mold plate is connected to the outer side wall of the clamping mechanism via a chain ring.

[0027] Therefore, the present invention has the following beneficial effects: (1) The present invention helps to improve the utilization rate of raw materials, save costs, and further improve production efficiency by controlling the selection of raw materials and accurately calculating the cutting length; (2) The present invention designs a high-strength, corrosion-resistant material forming device with a unique structure to cold-extrude and heat-treat the steel pipe, thereby manufacturing a high-strength, corrosion-resistant, integrated oblique tee, which will be suitable for pipeline systems under special working conditions in most petroleum, chemical and other fields in the future, further improving its practicality and having a wide range of applications; (3) The forming device used in the manufacturing process of the oblique tee of the present invention is made of high-hardness pre-hardened steel (made of 40Cr, nitrided to HRC52-56 after quenching and tempering), which helps to ensure the service life and production efficiency of the forming device; (4) The present invention covers the sizes of oblique tees of DN600 and below, designs oblique tee molds of multiple sizes, and simulates the material flowability from the perspective of molding device design, thereby ensuring the integrated molding of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the cross-sectional structure of the half-mold assembly.

[0029] Figure 2 It is a schematic diagram of the longitudinal section structure of the second half mold.

[0030] Figure 3 It is a schematic diagram of the assembly structure of the molding device and the upper and lower templates.

[0031] Figure 4 Schematic diagram of the manufacturing process flow of the oblique tee.

[0032] Figure 5 It is a schematic diagram of the oblique tee of the present invention.

[0033] In the figure: half mold assembly 1; first half mold 2; second half mold 3; mold cavity 4; guide block 5; groove 6; positioning bolt hole 7; clamping mechanism 8; punch 9; upper punch 10; lower punch 11; upper mold plate 12; lower mold plate 13. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments of the specification. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0035] Example 1 This embodiment provides a molding device used in the manufacturing process of an oblique tee.

[0036] like Figure 1-3As shown, the molding device used in the manufacturing process of the oblique tee of the present invention includes a half mold assembly 1. The half mold assembly 1 includes a first half mold 2 and a second half mold 3, and a mold cavity 4 for molding the shape of the product is provided in the first half mold 2 and the second half mold 3. Guide blocks 5 for guiding when closing the mold are provided on the longitudinal section of the first half mold 2 and on both sides of the mold cavity 4. Grooves 6 adapted to the guide blocks 5 are provided on the longitudinal section of the second half mold 3 and on both sides of the mold cavity 4. A plurality of positioning bolt holes 7 are provided on the outer side walls of the first half mold 2 and the second half mold 3. The molding device of the present invention also includes a clamping mechanism 8 sleeved on the outer side of the half mold assembly 1 and used to clamp the half mold assembly 1. The molding device of the present invention also includes a punch 9 for cold extrusion of the product. The punch 9 includes an upper punch 10 and a lower punch 11, the lower end of the upper punch 10 is inserted into the mold cavity 4, and the upper end of the upper punch 10 protrudes upward in a direction away from the top of the half mold assembly 1. The upper end of the lower punch 11 is inserted into the die cavity 4 , and the lower end of the lower punch 11 protrudes downward in a direction away from the bottom of the half-die assembly 1 .

[0037] Unlike traditional oblique tees, which are prone to fatigue cracking due to variable stress on the weld, the oblique tee of the present invention has the characteristics of integrated molding and outstanding load-bearing capacity. The molding device used in the manufacturing process of the oblique tee of the present invention selects high-hardness pre-hardened steel, which helps to ensure the service life and production efficiency of the molding device. In addition, the present invention restores the product size structure 1:1 according to the size of the oblique tee, simulates the material flowability from the design of the molding device, and thus ensures the integrated molding of the product.

[0038] As an implementation mode, the cross-sectional shape of the first half mold 2 and the second half mold 3 are both semicircular ring-shaped; the cross-sectional shape of the punch 9 is rectangular; and the cross-sectional shape of the clamping mechanism 8 is circular ring-shaped.

[0039] As an implementation manner, the number of the guide blocks 5 is at least four.

[0040] By providing the guide block 5 and plugging and using it in conjunction with the groove 6, it helps to improve the mold closing accuracy, thereby improving the molding accuracy and consistency of the product. At the same time, the mutual cooperation between the guide block 5 and the groove 6 not only provides guidance for the mold closing process, but also plays a supporting role after the mold closing, thereby enhancing the overall stability of the mold. In addition, the smooth cooperation between the guide block 5 and the groove 6 can achieve rapid mold closing, further improving production efficiency.

[0041] As an implementation manner, the number of the positioning bolt holes 7 is at least four.

[0042] The positioning bolt holes 7 are provided to facilitate accurate alignment and fastening of the first half mold 2 and the second half mold 3 during the mold closing process, thereby preventing displacement or misalignment during the molding process, thereby ensuring accurate mold closing. At the same time, the design of the positioning bolt holes 7 makes the installation and removal process of the mold simpler and faster, thereby improving work efficiency and facilitating mold transportation.

[0043] As an implementation manner, an upper template 12 is disposed above the upper punch 10 , and the upper template 12 is detachably connected to the outer side wall of the clamping mechanism 8 , and a lower template 13 is disposed below the lower punch 11 .

[0044] As an implementation mode, the upper mold plate 12 is connected to the outer side wall of the clamping mechanism 8 via a chain ring.

[0045] Example 2 The present embodiment provides a manufacturing process of an oblique tee. The manufacturing process of the oblique tee in the present embodiment uses the molding device in the embodiment 1.

[0046] This embodiment provides an equal diameter oblique tee of Φ168.3×10.97 (the outer diameter of the main pipe and the branch pipe is 168.3mm, and the wall thickness of the main pipe and the branch pipe is 10.97mm, recorded as Φ168.3×10.97.

[0047] A manufacturing process of an oblique tee comprises the following steps: (S.1) Selection of raw materials: Select the seamless steel pipe made of nickel-based alloy N06625 as the raw material. The outer diameter of the seamless steel pipe made of nickel-based alloy N06625 is the same as the outer diameter of the main pipe of the inclined tee, and the outer diameter of the seamless steel pipe made of nickel-based alloy N06625 is 168.3mm; the wall thickness of the seamless steel pipe made of nickel-based alloy N06625 is 1.4 times the nominal wall thickness of the main pipe of the inclined tee, and the wall thickness of the seamless steel pipe made of nickel-based alloy N06625 is 15.4mm. Calculate the cutting length of the seamless steel pipe made of nickel-based alloy N06625 according to the following formula.

[0048] Cutting length = A + B + C * X; In the formula, A represents the length from the center of the main pipe of the inclined tee to the end face of the main pipe close to the center of the main pipe, B represents the length from the center of the main pipe of the inclined tee to the end face of the main pipe far from the center of the main pipe, C represents the length from the center of the main pipe of the inclined tee to the end face of the branch pipe, and X represents the proportional coefficient corresponding to the outer diameter of the main pipe of the inclined tee, and X is 1.0 to 2.0. The schematic diagram of the seamless inclined tee of the present invention is shown in FIG. Figure 5 As shown. Among them, A = 80mm; B = 270mm; C = 270mm; X = 1.18. Calculation shows that the blanking length = A + B + C * X = 668.6mm. Confirm that the final blanking length is 670mm and the wall thickness of the feed material is 15.4mm.

[0049] (S.2) Cold extrusion molding: The seamless steel pipe made of nickel-based alloy N06625 is cut according to the blanking length and the surface of the seamless steel pipe made of nickel-based alloy N06625 after blanking is ground, and then the ground seamless steel pipe made of nickel-based alloy N06625 is graphite lubricated, and then filled with solid medium. The solid medium used in this embodiment is a mixture of clay, graphite, and lubricating oil, and the mass ratio of clay, graphite, and lubricating oil contained in the solid medium is 10-20:1-5:0.2-0.5. Among them, the optimal mass ratio of clay, graphite, and lubricating oil contained in the solid medium selected in this embodiment is 10:1:0.2. Then put it into the half-mold assembly in the molding device designed and prepared in Example 1, use a 10,000t four-column hydraulic press to lock the half-mold assembly, and use a punch to cold-extrude and press the main pipe end of the oblique tee. The internal pressure of the solid medium formed during solid medium filling is 535.9MPa. The molding amount of the first pressing is 50% of the original state. After molding, stress relief heat treatment is required, and then the final product is molded. The molding parameters are the same as the first molding, and a top block is added to the end face of the branch pipe during the last pressing process to ensure that the wall thickness of the branch pipe meets the requirements. Thus, the oblique tee blank is obtained, and it is degreased to remove the surface lubrication of the seamless steel pipe made of nickel-based alloy N06625. As another embodiment, when a welded steel pipe is selected as the raw material, the weld of the welded steel pipe should be placed opposite the branch pipe, and then the half-mold assembly is locked.

[0050] (S.3) Heat treatment: The oblique tee blank obtained in step (S.2) is heat treated at 900℃ with a holding time of 55min and water-cooled to obtain a seamless oblique tee. The branch pipe caps of the seamless oblique tee are then removed to verify whether the wall thickness of the product meets the design requirements. The product is then pickled to remove surface grease, scale, residual acid, etc., and then the seamless oblique tee is shaped to ensure that the product meets the requirements. The inner holes of the branch pipe and the main pipe of the seamless oblique tee are then machined, and the ends are beveled and the appearance of the product is surface treated. Finally, the product is subjected to non-destructive testing to ensure product performance, and passivation treatment is performed to clean the surface to ensure product appearance. Surface and appearance inspections, dimensional inspections, and PMI tests are then carried out. The schematic diagram of the manufacturing process flow of the seamless oblique tee is shown in the figure. Figure 4 shown.

[0051] Example 3 The difference between this embodiment and embodiment 2 is that: This embodiment provides an oblique tee of Φ168.3×12.7 / Φ89×7.62 (the outer diameter of the main pipe is 168.3 mm, the wall thickness of the main pipe is 12.7 mm, the outer diameter of the branch pipe is 89 mm, the wall thickness of the branch pipe is 7.62 mm, recorded as Φ168.3×12.7 / Φ89×7.62). The manufacturing process of the oblique tee in this embodiment uses the molding device in Example 1.

[0052] A manufacturing process for an oblique tee, wherein in step (S.1), a seamless steel pipe made of N06625 is selected as the raw material, the outer diameter of the seamless steel pipe made of N06625 is the same as the outer diameter of the main pipe of the oblique tee, and the outer diameter of the seamless steel pipe made of N06625 is 168.3 mm; the wall thickness of the seamless steel pipe made of N06625 is 1.3 times the nominal wall thickness of the main pipe of the oblique tee, and the wall thickness of the seamless steel pipe made of N06625 is 16.5 mm. Among them, A = 80 mm; B = 270 mm; C = 255 mm; X = 1.2. It is calculated that the blanking length = A + B + C * X = 656 mm. Confirm that the final blanking length is 660mm and the wall thickness of the feed is 16.5mm; in step (S.2), a 10000t four-column hydraulic press is used to lock the half-mold assembly, and the main pipe end of the oblique tee is cold extruded and pressed with a punch. The internal pressure of the solid medium formed during solid medium filling is 548.9MPa. The molding amount of the first pressing is 60% of the original state. After molding, stress relief heat treatment is required, and then the final product is molded. The molding parameters are the same as the first molding, and a top block is added to the end face of the branch pipe during the last pressing process to ensure that the wall thickness of the branch pipe meets the requirements. Thus, an oblique tee blank is obtained, and it is degreased to remove the surface lubrication of the seamless steel pipe made of nickel-based alloy N06625; in step (S.3), the oblique tee blank obtained in step (S.2) is heat treated at 900℃, and the insulation time is 55min. The rest is the same as in Example 2.

[0053] Example 4 The difference between this embodiment and embodiment 2 is that: This embodiment provides an equal diameter oblique tee of Φ168.3×9 (the outer diameter of the main pipe and the branch pipe is 168.3mm, and the wall thickness of the main pipe and the branch pipe is 9mm, recorded as Φ168.3×9. The manufacturing process of the oblique tee in this embodiment uses the molding device in Example 1.

[0054] A manufacturing process of an oblique tee, wherein in step (S.1), a seamless steel pipe made of S32205 is selected as the raw material, the outer diameter of the seamless steel pipe made of S32205 is the same as the outer diameter of the main pipe of the oblique tee, and the outer diameter of the seamless steel pipe made of S32205 is 168.3 mm; the wall thickness of the seamless steel pipe made of S32205 is 1.8 times the nominal wall thickness of the main pipe of the oblique tee, and the wall thickness of the seamless steel pipe made of S32205 is 16.2 mm. Among them, A = 80 mm; B = 270 mm; C = 270 mm; X = 1.2. It is calculated that the blanking length = A + B + C * X = 674 mm. Confirm that the final blanking length is 675mm and the wall thickness of the feed material is 16.2mm; in step (S.2), a 10000t four-column hydraulic press is used to lock the half-mold assembly, and the main pipe end of the oblique tee is cold extruded and pressed by a punch. The internal pressure of the solid medium formed during solid medium filling is 458.8MPa, and the molding amount of the first pressing is 50% of the original state. After molding, stress relief heat treatment is required, and then the final product is molded. The molding parameters are the same as the first molding, and a top block is added to the end face of the branch pipe during the last pressing process to ensure that the wall thickness of the branch pipe meets the requirements; in step (S.3), the oblique tee blank obtained in step (S.2) is heat treated at 1180°C, and the insulation time is 40min. The rest is the same as in Example 2.

[0055]

Performance test

[0056] Room temperature tensile test: Test method reference standard ASTM E8 / E8M-21; Hardness test: Test method reference standard ASTM A370-20; Intergranular corrosion test: Test method reference standard ASTM G28-02 (R2015) A; Metallographic examination: The test method refers to the standard ASTM A923-14 Method A.

[0057] Table 1

[0058] The performance of the oblique tee prepared according to the method in Example 4 was tested, and the test results are shown in Table 2 below.

[0059] Room temperature tensile test: Test method reference standard ASTM A370-19e1; Hardness test: Test method reference standard ASTM A370-20; Intergranular corrosion test: Test method reference standard ASTM A262-15 E; Metallographic examination: Test method reference standard ASTM A923-14 Method A; Ferrite test: The test method refers to standard ASTM E562-19.

[0060] Table 2

[0061] It can be seen from Table 1 and Table 2 that the test performance of the oblique tee provided in the embodiment of the present invention fully meets the requirements for use under special working conditions such as high temperature resistance, corrosion resistance, and pickling resistance.

[0062] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A manufacturing process of an oblique tee, characterized in that: The following steps are involved: (S.1) Selection of raw materials: A steel pipe is selected as the raw material, the outer diameter of the steel pipe is the same as the outer diameter of the main pipe of the oblique tee, and the wall thickness of the steel pipe is 1.2 to 2.5 times the nominal wall thickness of the main pipe of the oblique tee; the cutting length of the steel pipe is calculated according to the following formula; Cutting length = A + B + C * X; In the formula, A represents the length from the center of the main pipe of the inclined tee to the end face of the main pipe close to the center of the main pipe, B represents the length from the center of the main pipe of the inclined tee to the end face of the main pipe far from the center of the main pipe, C represents the length from the center of the main pipe of the inclined tee to the end face of the branch pipe, X represents the proportional coefficient corresponding to the outer diameter of the main pipe of the inclined tee, and X is 1.0 to 2.0; (S.2) Cold extrusion molding: Cut the steel pipe according to the blanking length and fill the blanked steel pipe with a solid medium, wherein the solid medium includes clay, graphite and lubricating oil, and the mass ratio of clay, graphite and lubricating oil in the solid medium is 10-20:1-5:0.2-0.5, and then put it into a mold in a molding device, lock the mold, and use a punch to perform multiple cold extrusions on the main pipe end of the oblique tee, and mold in batches to obtain an oblique tee blank; (S.3) Heat treatment: The oblique tee blank obtained in step (S.2) is heat treated and water-cooled to obtain the oblique tee, which is then pickled, machined, and inspected.

2. The manufacturing process of the oblique tee according to claim 1, characterized in that: The material of the steel pipe is any one of duplex steel S31803, duplex steel S32205, duplex steel S32750, duplex steel S32760, nickel-based alloy N04400, nickel-based alloy N06600, nickel-based alloy N06625, nickel-based alloy N08800, nickel-based alloy N08825, nickel-based alloy N08810, and nickel-based alloy N08020.

3. The manufacturing process of the oblique tee according to claim 1, characterized in that: In step (S.2), the second cold extrusion molding amount in the two adjacent cold extrusion molding processes is 10-60% of the first cold extrusion molding amount; and stress relief heat treatment is required between the two adjacent cold extrusion molding processes.

4. The manufacturing process of the oblique tee according to claim 1, characterized in that: The internal molding pressure formed during the solid medium filling in step (S.2) is 30 to 600 MPa.

5. The manufacturing process of the oblique tee according to claim 1, characterized in that: When the material of the steel pipe is dual-phase steel, the heating temperature for heat treatment of the oblique tee blank in step (S.3) is 1020-1140°C; when the material of the steel pipe is nickel-based alloy, the heating temperature for heat treatment of the oblique tee blank in step (S.3) is 900-1180°C.

6. A molding device used in the manufacturing process of the oblique tee according to any one of claims 1 to 5, characterized in that: include: A half-mold assembly (1), comprising a first half-mold (2) and a second half-mold (3), wherein a mold cavity (4) for molding a product shape is disposed in the first half-mold (2) and the second half-mold (3), guide blocks (5) for guiding when the molds are closed are disposed on the longitudinal section of the first half-mold (2) and on both sides of the mold cavity (4), grooves (6) adapted to the guide blocks (5) are disposed on the longitudinal section of the second half-mold (3) and on both sides of the mold cavity (4), and a plurality of positioning bolt holes (7) are disposed on the outer side walls of the first half-mold (2) and the second half-mold (3); A mold locking mechanism (8) is sleeved on the outer side of the mold half assembly (1) and is used to lock the mold half assembly (1); A punch (9) is used to perform cold extrusion on a product, the punch (9) comprising an upper punch (10) and a lower punch (11), the lower end of the upper punch (10) being inserted into the interior of a die cavity (4), the upper end of the upper punch (10) being protruding upward in a direction away from the top of a half-die assembly (1), the upper end of the lower punch (11) being inserted into the interior of the die cavity (4), the lower end of the lower punch (11) being protruding downward in a direction away from the bottom of the half-die assembly (1).

7. A molding device according to claim 6, characterized in that: The cross-sectional shapes of the first half mold (2) and the second half mold (3) are both semi-circular; the cross-sectional shape of the punch (9) is rectangular; and the cross-sectional shape of the clamping mechanism (8) is circular.

8. A molding device according to claim 6, characterized in that: The number of the guide blocks (5) is at least four.

9. A molding device according to claim 6, characterized in that: An upper mold plate (12) is arranged above the upper punch (10), and the upper mold plate (12) is detachably connected to the outer side wall of the mold locking mechanism (8). A lower mold plate (13) is arranged below the lower punch (11).

10. A molding device according to claim 9, characterized in that: The upper mold plate (12) is connected to the outer side wall of the mold locking mechanism (8) via a chain link.

Images