Branch pipe hot extrusion forming method and pipe fitting

Abstract

The invention discloses a branch pipe hot extrusion forming method and a pipe fitting, belongs to the technical field of pipe fitting branch pipe forming, and is designed for solving the problem that an existing machining method has high performance requirements on a pressurizing device. According to the branch pipe hot extrusion forming method, a pipe fitting blank filled with an extrusion medium is heated, after the pipe fitting blank is heated to the set temperature, the pipe fitting blank and the extrusion medium are pressurized at the same time in a mold till the flowing extrusion medium is extruded on the side wall of the pipe fitting blank to form a branch pipe, and the wall thickness of the branch pipe is larger than a set value. According to the branch pipe hot extrusion forming method and the pipe fitting, the pipe fitting blank becomes softer through a heating method, the pipe fitting blank can be pressed to be short in the axial direction through small force, extrusion work can be completed through a common pressure applying device, and the machining cost is low; the branch pipe is machined according to the bulging principle of the metal pipe fitting, the branch pipe and the pipe body are integrally formed, stress concentration at the joint of the branch pipe and the pipe body is avoided, and the overall strength of the pipe fitting is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of forming of branch pipes of pipe fittings, and particularly to a method for hot extrusion forming of branch pipes and pipe fittings. Background Art

[0002] In order to change the flow direction of at least part of the fluid flowing in a pipeline, a branch pipe can be connected to the side wall of the pipeline. The extending direction of the branch pipe forms an angle with the extending direction of the pipeline, and the flow direction of the fluid entering the branch pipe changes relative to the pipeline.

[0003] By opening a through hole in the side wall of the pipeline and welding the branch pipe at the through hole, the flow direction of the fluid can be changed. However, the strength of the connection between the branch pipe and the pipeline is poor. When the fluid changes the flow direction, it will impact the connection between the branch pipe and the pipeline, which may cause deformation or damage at the connection between the branch pipe and the pipeline, and the fluid may leak here. To solve this problem, some existing processing methods for branch pipes are as follows: selecting a pipeline blank made of a metal with good ductility, filling a fluid substance in the pipeline blank, sealing both ends of the pipeline blank, and then putting the whole into a mold. The side of the mold is provided with a through hole. The two ends of the pipeline blank are strongly extruded until it becomes shorter. The side wall of the pipeline blank enters the through hole on the side of the mold under the extrusion of the fluid substance inside it to form a branch pipe.

[0004] The defects of the existing method for extruding and forming branch pipes include: metal materials are usually high in strength and relatively hard, and a large extrusion force is required to make them shorter, which requires high performance of the pressurizing device; the fluid substance filled in the pipeline blank is usually in the form of fine particles, and the pressure formed on the side wall of the pipeline blank is uneven, and the shape and size of the formed branch pipe are not ideal, and the processing efficiency is low. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for hot extrusion forming of branch pipes and pipe fittings, which solves the problem of high performance requirements for the pressurizing device in the existing processing method and has a wide range of applications.

[0006] To achieve this purpose, on the one hand, the present invention adopts the following technical solutions:

[0007] A method for hot extrusion forming of a branch pipe, heating a pipe fitting blank filled with an extrusion medium inside, and simultaneously pressurizing the pipe fitting blank and the extrusion medium in a mold after heating to a set temperature until the flowing extrusion medium extrudes and forms a branch pipe on the side wall of the pipe fitting blank, and the wall thickness of the branch pipe is greater than a set value.

[0008] In one preferred embodiment, sealing members are respectively arranged at both ends of the pipe fitting blank. An accommodating cavity is formed between the pipe fitting blank and the two sealing members, and the extrusion medium in the form of solid powder or semi-solid state is filled in the accommodating cavity. The root of the branch pipe is located on the side wall of the accommodating cavity.

[0009] In one preferred embodiment, the method for hot extrusion forming of the branch pipe comprises the following steps:

[0010] Step S1: Insert one of the plugging members through one end of the pipe fitting blank and seal and connect it. Fill the extrusion medium into the pipe fitting blank from the other end, and insert the other plugging member through the other end of the pipe fitting blank and seal and connect it;

[0011] Step S2: Heat the pipe fitting blank to a set temperature;

[0012] Step S3: Place the pipe fitting blank in the lower die forming cavity of the lower die, such that the lower die branch pipe forming hole opened on the side wall of the lower die is located between the two plugging members;

[0013] Step S4: Close the upper die on the lower die. The pipe fitting blank is located in the upper die forming cavity of the upper die, and the upper die branch pipe forming hole opened on the side wall of the upper die is aligned with the lower die branch pipe forming hole;

[0014] Step S5: The pressurizing device applies pressure to the pipe fitting blank and the plugging members, so as to cause the pipe fitting blank to shorten axially and the extrusion medium to flow in the pipe fitting blank;

[0015] Step S6: When the axial length of the pipe fitting blank reaches the set value, take out the pipe fitting blank from the upper die and the lower die, and determine whether the shape and size of the branch pipe meet the processing requirements; if yes, the processing is completed, otherwise N = N + 1;

[0016] Step S7: When N = 1, go back to continue Step S2; when N ≥ 2, go to Step S3.

[0017] In one preferred embodiment, the method for hot extrusion forming of the branch pipe further comprises: after the shape and size of the branch pipe meet the processing requirements, remove the plugging members and the extrusion medium, and perform cutting on the inner walls of the branch pipe and the pipe body formed by the pipe fitting blank until the diameters of the branch pipe and the pipe body reach the set value.

[0018] In one preferred embodiment, in Step S6, after determining that the shape and size of the branch pipe do not meet the processing requirements, measure the wall thickness of the pipe fitting blank and the branch pipe, and the part with the thinner wall thickness will be the key force application position for the next extrusion.

[0019] In one preferred embodiment, in Step S2, the heating temperature of the pipe fitting blank is in the range of 900°C to 1000°C.

[0020] In one preferred embodiment, the difference between the distance between the two plugging members and the branch pipe is within a set value.

[0021] In one preferred embodiment, the extrusion medium is a mixture of molten salt and carbon powder.

[0022] On the other hand, the present invention adopts the following technical solutions:

[0023] A pipe fitting, comprising an integrally formed branch pipe and a pipe body, and the branch pipe and the pipe body are processed by the above-mentioned branch pipe hot extrusion forming method.

[0024] In one preferred embodiment, the branch pipe is inclined at a set angle with respect to the pipe body.

[0025] The branch pipe hot extrusion forming method disclosed by the present invention makes the pipe fitting blank softer through heating, and can also shorten it axially with a smaller force, and an ordinary pressure applying device can complete the extrusion work, with low processing cost; the branch pipe is processed by using the principle of metal pipe fitting bulging, so that the branch pipe and the pipe body are integrally formed, avoiding stress concentration at the connection between the branch pipe and the pipe body, and the overall strength of the pipe fitting is higher.

[0026] The branch pipe and the pipe body of the pipe fitting disclosed by the present invention are processed by the above-mentioned branch pipe hot extrusion forming method, and the connection between the branch pipe and the pipe body has higher strength, can withstand long-term and strong impact of fluid, is safer to use, and has a wide application range. Brief Description of the Drawings

[0027] Figure 1 is a schematic diagram of the combined structure of the branch pipe and the pipe body provided by the specific embodiment of the present invention;

[0028] Figure 2 is a cross-sectional view of the combined structure of the branch pipe, the pipe body, the extrusion medium and the plugging member provided by the specific embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of the combined structure of the pipe fitting blank, the plugging member, the lower die and the upper die provided by the specific embodiment of the present invention.

[0030] In the figure:

[0031] 1. Extrusion medium; 2. Pipe fitting blank; 3. Plugging member; 4. Lower die; 5. Upper die; 21. Branch pipe; 22. Pipe body; 41. Lower die forming cavity; 42. Lower die branch pipe forming hole; 51. Upper die forming cavity; 52. Upper die branch pipe forming hole; 211. Plugging end; 212. Rough machining inner wall surface; 221. End pipe inner wall; 222. Middle pipe inner wall. Detailed Description of the Invention

[0032] In order to make the above objects, features, and advantages of the present invention more apparent and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0034] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0035] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over", and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below", and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0037] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation.

[0038] This embodiment discloses a pipe fitting and a method for hot extrusion forming of a branch pipe for processing the pipe fitting, as Figure 1 and Figure 2 shown. The pipe fitting includes an integrally formed branch pipe 21 and a pipe body 22, which is obtained by using the hot extrusion forming method of the branch pipe. The connection strength between the branch pipe 21 and the pipe body 22 is higher, and it can withstand the long-term strong impact of the fluid, making it safer to use and having a wide range of applications.

[0039] The specific structure of the pipe fitting is not limited. In this embodiment, the branch pipe 21 is set at an inclined angle relative to the pipe body 22, and the inside of the branch pipe 21 is connected to the inside of the pipe body 22. Part of the fluid in the pipe body 22 changes the flow direction after entering the branch pipe 21, and the other fluid in the pipe body 22 still flows along the pipe body 22, thus dividing the original one-way fluid into two-way, realizing fluid diversion.

[0040] The parameters such as the diameter and wall thickness of the branch pipe 21 and the pipe body 22 can be the same, which is convenient for processing; they can also be different, and can be designed according to actual use requirements, saving materials and reducing costs while ensuring performance and wall thickness.

[0041] As Figures 1 to 3 shown, the hot extrusion forming method of the branch pipe: heat the pipe fitting blank 2 filled with the extrusion medium 1 inside, and after heating to the set temperature, apply pressure to the pipe fitting blank 2 and the extrusion medium 1 simultaneously in the mold until the flowing extrusion medium 1 extrudes and forms the branch pipe 21 on the side wall of the pipe fitting blank 2, and the wall thickness of the branch pipe 21 is greater than the set value.

[0042] This hot extrusion forming method of the branch pipe utilizes the principle of metal pipe fitting bulging to process the branch pipe 21, making the branch pipe 21 and the pipe body 22 integrally formed, avoiding stress concentration at the connection between the branch pipe 21 and the pipe body 22, and making the overall strength of the pipe fitting higher; the ability to extrude the pipe fitting blank 2 and the extrusion medium 1 makes the pipe fitting blank 2 shorter in the axial direction, and the shortened material is used to form the branch pipe 21, and the overall volume remains unchanged, avoiding the inability to form the branch pipe 21 due to insufficient materials, and ensuring that the shape and various dimensional parameters of the branch pipe 21 and the pipe body 22 meet the requirements.

[0043] This method for hot extrusion forming of the branch pipe makes the pipe blank 2 softer by heating, and it can be axially compressed and shortened with a smaller force. An ordinary pressure application device can complete the extrusion work, with low processing costs.

[0044] The specific method of applying pressure to the pipe blank 2 and the extrusion medium 1 is not limited. It can be carried out synchronously or asynchronously at both ends of the pipe blank 2, as long as the extrusion medium 1 can flow after the pipe blank 2 bears the pressure.

[0045] The shape and size of the pipe blank 2 are not limited and can be determined according to the actual situation. In this embodiment, the shape of the pipe blank 2 is basically the same as that of the pipe body 22 to be processed, reducing the processing difficulty of the pipe body 22 and improving the processing efficiency. The volume of the pipe blank 2 is equal to the sum of the volumes of the branch pipe 21 and the pipe body 22 to be processed. Given that the wall thickness of the branch pipe 21 and the pipe body 22 will be slightly larger than the target value after extrusion forming, the volume of the pipe blank 2 needs to be slightly larger than the sum of the volumes of the branch pipe 21 and the pipe body 22 to leave enough margin for the wall thickness.

[0046] To prevent the extrusion medium 1 from flowing out from the ends of the pipe blank 2, in this embodiment, sealing members 3 are respectively provided at both ends of the pipe blank 2. An accommodation cavity is formed between the pipe blank 2 and the two sealing members 3, and the extrusion medium 1 in the form of solid powder or semi-solid state is filled in the accommodation cavity. The root of the branch pipe 21 is located on the side wall of the accommodation cavity. The extrusion medium 1 in the form of solid powder or semi-solid state will flow towards the position with the minimum pressure value on the outer wall of the pipe blank 2 under pressure, evenly pressing on the pipe wall of the pipe blank 2, making it easier to process a qualified branch pipe 21 with the correct shape and size and improving the processing efficiency.

[0047] The mold used in this method for hot extrusion forming of the branch pipe includes an upper mold 5 and a lower mold 4. Specifically, a lower mold forming cavity 41 is penetrated in the middle of the lower mold 4, and a lower mold branch pipe forming hole 42 is opened on the side wall of the lower mold 4. The lower mold branch pipe forming hole 42 is communicated with the lower mold forming cavity 41; an upper mold forming cavity 51 is penetrated in the middle of the upper mold 5, and an upper mold branch pipe forming hole 52 is opened on the side wall of the upper mold 5. After the upper mold 5 and the lower mold 4 are closed, the upper mold forming cavity 51 and the lower mold forming cavity 41 together form a space for placing the pipe blank 2, and the final pipe body 22 will be formed in this space; the upper mold branch pipe forming hole 52 is aligned with the lower mold branch pipe forming hole 42 to jointly form a through hole for processing the branch pipe 21.

[0048] The specific shape and size of the through hole for processing the branch pipe 21 are not limited, and are basically the same as the shape and size of the branch pipe 21. The inclination angle of the branch pipe 21 relative to the pipe body 22 is equal to the inclination angle of the axis of the through hole relative to the axis of the space enclosed by the upper die forming cavity 51 and the lower die forming cavity 41. For example, when the branch pipe 21 is orthogonal to the pipe body 22, the axis of the through hole is perpendicular to the axis of the space enclosed by the upper die forming cavity 51 and the lower die forming cavity 41; when the branch pipe 21 is inclined at 45° relative to the pipe body 22, the included angle between the axis of the through hole and the axis of the space enclosed by the upper die forming cavity 51 and the lower die forming cavity 41 is also 45°.

[0049] Based on the above structure, the specific composition of the extrusion medium 1 is not limited, as long as it can be in the form of solid powder or semi-solid state after high-temperature heating and can flow and extrude to form the branch pipe 21 under the action of pressure. In this embodiment, the extrusion medium 1 is a mixture of molten salt and carbon powder. In an environment of 900°C to 1000°C, the mixture of molten salt and carbon powder is in powder form or semi-powder and semi-molten state, not easily caking, with good fluidity and a small friction coefficient during flow, and can smoothly extrude to form the branch pipe 21 on the side wall of the pipe blank 2, with high production efficiency; after the branch pipe 21 is processed and the whole is cooled down, the mixture of molten salt and carbon powder will not adhere to the inner walls of the branch pipe 21 and the pipe body 22, and the mixture of molten salt and carbon powder can be taken out conveniently and quickly, without affecting the subsequent processing of the branch pipe 21 and the pipe body 22.

[0050] The specific mixing ratio of the molten salt and carbon powder is not limited and can be adjusted according to the actual use situation, as long as it can be in the form of solid powder or semi-solid state after high-temperature heating and can flow and extrude to form the branch pipe 21 under the action of pressure.

[0051] The hot extrusion forming method for the branch pipe includes the following steps:

[0052] Step S1: Insert a plugging member 3 into one end of the pipe blank 2 and seal it, fill the extrusion medium 1 into the pipe blank 2 from the other end, and insert another plugging member 3 into the other end of the pipe blank 2 and seal it. The specific sealing connection method between the plugging member 3 and the pipe blank 2 is not limited and can be, but is not limited to, spot welding, as long as the outer peripheral surface of the plugging member 3 can be closely attached to the inner wall surface of the pipe blank 2 without a gap allowing the extrusion medium 1 to leak.

[0053] Step S2: Heat the pipe blank 2 to a set temperature. The specific setting of the set temperature is not limited, as long as it can reduce the strength of the pipe blank 2, improve the ductility of the material for preparing the pipe blank 2, and make it easy for the extrusion medium 1 to extrude to form the branch pipe 21 on the side wall of the pipe blank 2. In this embodiment, the set temperature is in the range of 900°C to 1000°C, the temperature value is easy to achieve and has high precision, and both the pipe blank 2 and the extrusion medium 1 are in a state where it is easy to process and form the branch pipe 21.

[0054] Step S3: Place the pipe fitting blank 2 with the plugging member 3 and the extrusion medium 1 inside into the lower die forming cavity 41, and use the inner wall surface of the lower die forming cavity 41 to limit the outer diameter of the pipe body 22. When placing the pipe fitting blank 2, make the lower die branch pipe forming hole 42 located between the two plugging members 3, so as to prevent the extrusion medium 1 from not being able to extrude the side wall material of the pipe fitting blank 2 into the lower die branch pipe forming hole 42 due to the blockage of the plugging member 3, and ensure that a branch pipe 21 with a shape and size meeting the design requirements can be formed in the lower die branch pipe forming hole 42.

[0055] Step S4: Close the upper die 5 on the lower die 4. The pipe fitting blank 2 is located in the upper die forming cavity 51 of the upper die 5. Similar to the lower die forming cavity 41, the inner wall surface of the upper die forming cavity 51 will also be used to limit the outer diameter of the pipe body 22. The upper die branch pipe forming hole 52 is aligned with the lower die branch pipe forming hole 42. The upper die branch pipe forming hole 52 and the lower die branch pipe forming hole 42 together form a cylindrical structure. There is no blockage from the inner wall surface of the lower die forming cavity 41 and the inner wall surface of the upper die forming cavity 51 within the range of the cylindrical structure. The material on the pipe fitting blank 2 can enter the cylindrical structure under the pushing of the extrusion medium 1 to form the branch pipe 21.

[0056] Step S5: The pressurizing device applies pressure to the pipe fitting blank 2 and the plugging member 3 to cause the pipe fitting blank 2 to shorten axially and the extrusion medium 1 to flow in the pipe fitting blank 2. The specific structure of the pressurizing device is not limited, as long as it can apply pressure to the pipe fitting blank 2 and the plugging member 3. For example, it can be a hydraulic push rod, an electric push rod, etc. The specific way of applying pressure is not limited. Two pressurizing devices can be used to simultaneously extrude the pipe fitting blank 2 and the plugging member 3 from both ends respectively, with high processing efficiency; or one end of the pipe fitting blank 2 and the plugging member 3 can be abutted against a fixing member, and the pressurizing device applies pressure to the other end, which can use one less pressurizing device and has a low cost.

[0057] Step S6: When the axial length of the pipe fitting blank 2 reaches the set value, take out the pipe fitting blank 2 from the upper die 5 and the lower die 4, and judge whether the shape and size of the branch pipe 21 meet the processing requirements. If both the shape and size of the branch pipe 21 have reached the design goal, end the processing program, take out both the plugging member 3 and the extrusion medium 1, cut off the plugging end 211 at the top of the branch pipe 21, and the overall structure formed by the branch pipe 21 and the pipe body 22 enters the next process; if the shape and size of the branch pipe 21 have not reached the design goal, N = N + 1, and the program proceeds to the next step. Among them, the initial value of N is 0, which is used to record the number of times the pipe fitting blank 2 is heated and extruded.

[0058] Step S7: When N = 1, go back to step S2 to continue. Heat the pipe fitting blank 2 and then continue to apply force for extrusion. When N ≥ 2, go to step S3 to directly continue to apply force for extrusion on the pipe fitting blank 2. That is, the pipe fitting blank 2 needs to be heated before the first two extrusion and pushing operations, while it does not need to be heated before the subsequent extrusion and pushing operations, which can save energy and reduce the time consumed by heating while ensuring the improvement of the hot extrusion forming efficiency of the branch pipe.

[0059] When the pipe fitting blank 2 is blanked, the side wall is relatively thick, leaving enough margin for processing the branch pipe 21, which can avoid becoming too thin or even damaged due to the continuous extrusion of the extrusion medium 1 and ensure the smooth forming of the branch pipe 21. This hot extrusion forming method for branch pipes is mainly applied in the field of processing thick-walled pipe fittings. The material consumption of the wall thickness of the pipe fitting blank 2 is more than the material consumption of the branch pipe 21 extended along the axis direction. In actual use, there has been no leakage in the plugging end 211 at the top of the branch pipe 21.

[0060] In order to further avoid the wall surface of the branch pipe 21 from being too thin or even damaged, in step S6, after it is determined that the shape and size of the branch pipe 21 do not meet the processing requirements, measure the wall thicknesses of the pipe fitting blank 2 and the branch pipe 21. The part with a thinner wall thickness will be the key force application position for the next extrusion, so as to make the wall thickness of each part more uniform, avoid deformation and wrinkles on the pipe fitting blank 2, and avoid being too thin and damaged on the branch pipe 21.

[0061] Specifically, more thrust can be applied on the side with a thinner wall thickness to make the material be pushed more here, realizing local compensation of the material and thus locally controlling the wall thickness. The specific device for measuring the wall thickness is not limited, and any device in the prior art that can externally measure the wall thickness of the pipe fitting can be used, such as related devices for ultrasonic thickness measurement.

[0062] In view of the fact that the deformation amounts of the pipe fitting blank 2 at different temperatures after being force-extruded are different, and it is impossible to strictly ensure that the temperature is the same everywhere after the pipe fitting blank 2 is heated, the temperature of each part of the pipe fitting blank 2 can be measured before each extrusion, and the pressure value applied to each part can be determined according to the temperature value to avoid the problem of uneven wall thickness due to excessive local extrusion. Specifically, for the position with a higher temperature, a smaller pressure can be applied from both ends of the pipe fitting blank 2 to achieve the same pushing distance; for the position with a lower temperature, a larger pressure needs to be applied from both ends of the pipe fitting blank 2 to achieve the same pushing distance. The specific device for measuring the temperature is not limited, and any device in the prior art that can measure the temperature of the heated pipe fitting blank 2 can be used, such as an infrared remote sensing temperature measurement device and a remote sensing temperature measurement gun.

[0063] The overall shape of the extruded medium 1 after being subjected to force cannot be precisely controlled, and the rough-machined inner wall surface 212 of the branch pipe 21 and the middle inner wall 222 of the pipe body 22 cannot form a flat tubular structure of set size. When the wall thickness of the branch pipe 21 and the pipe body 22 is too thin, there are few subsequent remedial methods, and the process is difficult and costly. Therefore, the wall thickness of the branch pipe 21 and the pipe body 22 after extrusion exceeds the set value by cutting more materials. There are many methods to remove the excess wall thickness, and the process is easy.

[0064] In this embodiment, the branch pipe hot extrusion forming method also includes: after the shape and size of the branch pipe 21 meet the processing requirements, the plugging piece 3 and the extrusion medium 1 are removed, and the inner walls of the branch pipe 21 and the pipe body 22 formed by the pipe blank 2 are cut until the diameters of the branch pipe 21 and the pipe body 22 reach the set value. The specific cutting method is not limited, and can be but not limited to turning, which can easily and quickly remove the excess wall thickness inside. The inner wall surface after mechanical processing is smoother, the wall thickness value is more accurately controlled, the resistance is smaller when used to transport fluids, the fluid passes more smoothly, and the user experience is good.

[0065] In order to minimize the axial length of the inner wall surface that needs to be mechanically thinned, in this embodiment, the difference between the distance between the two blocking members 3 and the branch pipe 21 is within a set value range. The distance between the two blocking members 3 is not limited, as long as it is greater than the diameter of the branch pipe 21.

[0066] The plugging piece 3 is usually made of a relatively hard and high temperature resistant material. Heating and extrusion will not deform the plugging piece 3, so the parts at both ends of the pipe blank 2 that contact the plugging piece 3 form a relatively flat end tube inner wall 221. The wall thickness at the end of the pipe blank 2 is the radius of the lower mold forming cavity 41 (upper mold forming cavity 51) minus the radius of the plugging piece 3. The size is precisely controllable, so there is no need for subsequent mechanical processing at both ends of the pipe blank 2. The closer the two plugging pieces 3 are to each other, the shorter the section of the uneven middle tube inner wall 222 is, and the higher the processing efficiency is.

[0067] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A branch pipe hot extrusion forming method, characterized in that: A pipe blank (2) filled with an extrusion medium (1) is heated to a set temperature, and then the pipe blank (2) and the extrusion medium (1) are pressurized simultaneously in a mold until the flowing extrusion medium (1) is extruded on the side wall of the pipe blank (2) to form a branch pipe (21), wherein the wall thickness of the branch pipe (21) is greater than a set value.

2. The branch pipe hot extrusion forming method according to claim 1, characterized in that: Sealing pieces (3) are respectively provided at both ends of the pipe blank (2); a receiving cavity is formed between the pipe blank (2) and the two sealing pieces (3); the extrusion medium (1) in a solid powder or semi-solid state is filled in the receiving cavity; and the root of the branch pipe (21) is located on the side wall of the receiving cavity.

3. The branch pipe hot extrusion forming method according to claim 2, characterized in that: The branch pipe hot extrusion forming method comprises the following steps: Step S1, inserting one of the plugging members (3) through one end of the pipe blank (2) and sealingly connecting them, filling the extrusion medium (1) into the pipe blank (2) from the other end, inserting another of the plugging members (3) through the other end of the pipe blank (2) and sealingly connecting them; Step S2, heating the pipe blank (2) to a set temperature; Step S3, placing the pipe blank (2) in the lower die forming cavity (41) of the lower die (4), so that the lower die branch pipe forming hole (42) provided on the side wall of the lower die (4) is located between the two blocking members (3); Step S4, buckling the upper die (5) onto the lower die (4), the pipe blank (2) being located in the upper die forming cavity (51) of the upper die (5), and the upper die branch tube forming hole (52) provided on the side wall of the upper die (5) being aligned with the lower die branch tube forming hole (42); Step S5, the pressure device applies pressure to the pipe blank (2) and the blocking member (3) so as to shorten the pipe blank (2) in the axial direction and allow the extrusion medium (1) to flow in the pipe blank (2); Step S6, when the axial length of the pipe blank (2) reaches a set value, the pipe blank (2) is taken out from the upper die (5) and the lower die (4), and it is determined whether the shape and size of the branch pipe (21) meet the processing requirements; if yes, the processing is completed; otherwise, N=N+1; Step S7: when N=1, go to step S2; when N≥2, go to step S3.

4. The branch pipe hot extrusion forming method according to claim 3, characterized in that: The branch pipe hot extrusion forming method further comprises: after the shape and size of the branch pipe (21) meet the processing requirements, removing the blocking member (3) and the extrusion medium (1), and cutting the inner walls of the branch pipe (21) and the pipe body (22) formed by the pipe blank (2) until the diameters of the branch pipe (21) and the pipe body (22) reach a set value.

5. The branch pipe hot extrusion forming method according to claim 3, characterized in that: In step S6, after determining that the shape and size of the branch pipe (21) do not meet the processing requirements, the wall thickness of the pipe blank (2) and the branch pipe (21) is measured, and the thinner wall portion will be the focus of force application for the next extrusion.

6. The branch pipe hot extrusion forming method according to claim 3, characterized in that: In the step S2, the heating temperature of the pipe blank (2) is in the range of 900°C to 1000°C.

7. The branch pipe hot extrusion forming method according to any one of claims 2 to 6, characterized in that: The difference between the distance between the two blocking members (3) and the branch pipe (21) is within a set value.

8. The branch pipe hot extrusion forming method according to any one of claims 1 to 6, characterized in that: The extrusion medium (1) is a mixture of molten salt and carbon powder.

9. A pipe fitting, comprising a branch pipe (21) and a pipe body (22) formed in one piece, characterized in that: The branch pipe (21) and the pipe body (22) are obtained by using the branch pipe hot extrusion molding method according to any one of claims 1 to 8.

10. The pipe fitting according to claim 9, characterized in that The branch pipe (21) is inclined at a set angle relative to the pipe main body (22).

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