A kind of expansion head of extruded grooved pipe and grooved pipe processing method

Abstract

The present invention relates to an expansion head for an extruded grooved tube and a method for processing the grooved tube. The expansion head comprises an expansion portion and a connecting portion. The expansion portion is in the shape of a truncated cone, and a plurality of expansion teeth are evenly spaced and distributed on the sidewall surface of the truncated cone. The expansion teeth extend from the bottom of the truncated cone to the bottom of the truncated cone, and the expansion teeth and the axis of the truncated cone are located in the same plane. The diameter of the bottom of the truncated cone is smaller than the inner diameter of the grooved tube, and the diameter of the bottom of the truncated cone is larger than the inner diameter of the grooved tube. The connecting portion and the expansion portion are coaxially arranged, with one end being connected to an expansion rod and the other end being connected to the bottom of the truncated cone of the expansion portion. The expansion teeth contact the inner wall of a metal smooth tube and expand. The plurality of evenly spaced expansion teeth expand a plurality of spaced grooves in the inner wall of the metal smooth tube. A plurality of spike structures spliced ​​in sequence are formed between the final formed grooves. This spike structure forms a micro-nanostructure that can improve the phase change efficiency of the working medium, thereby effectively improving the performance of the heat pipe heat exchanger.

Description

Technical Field

[0001] The invention belongs to the technical field of metal inner groove tube processing, and particularly relates to an expansion head for an extruded grooved tube and a grooved tube processing method. Background Art

[0002] Industrial waste heat refers to the heat released by heat conversion equipment or energy-consuming equipment in the industrial and mining industries during production processes, including waste heat, wastewater, and exhaust gases. It is a low-grade energy source. The production processes of traditional energy-intensive industries such as coal, oil, steel, chemicals, and machinery generate significant amounts of industrial waste heat, making it considered the fifth largest conventional energy source, alongside coal, oil, natural gas, and hydropower. my country has enormous untapped potential for waste heat recovery.

[0003] Heat pipe heat exchangers are often needed in the field of waste heat recovery. However, the heat exchange tubes used in heat pipe heat exchangers are mostly plain tubes, which have a small heat exchange area and poor performance. Grooved tubes significantly increase the heat exchange area, and the micro-nano structure between the grooves is conducive to the phase change of the working fluid. Therefore, they are of great help in improving the performance of heat pipe heat exchangers.

[0004] The prior art discloses a grooved pipe processing device comprising a movable core head and an outer die that cooperates with the movable core head for drawing pipes. The movable core head has a first drawing end and a second drawing end, the first drawing end having a smaller diameter than the second drawing end. A truncated cone is formed between the first and second drawing ends, and the cone is provided with grooves spaced circumferentially and extending to the first drawing end. The movable core head acts as an inner die, cooperating with the outer die to draw the pipe, and during the drawing process, grooves are formed on the inner wall of the pipe. The pipe can be grooved in a single drawing process, reducing processing time.

[0005] It has the following technical problems: the floating core head needs to be used in conjunction with the external mold, and the processing process also requires a diameter reduction treatment. The process is relatively cumbersome, and it is impossible to process micro-nano structures between the grooves, making it difficult to further improve the phase change efficiency of the working fluid and the performance of the heat pipe exchanger. Summary of the Invention

[0006] In response to the technical problems existing in the prior art, one of the objectives of the present invention is to provide an expansion head for an extruded grooved tube, which can be used to extrude and expand the grooved tube in one step and process micro-nano structures between the grooves, which is beneficial to improving the phase change efficiency of the working fluid and improving the performance of the heat pipe exchanger.

[0007] In view of the technical problems existing in the prior art, the second purpose of the present invention is to provide a grooved tube processing method that can extrude and expand the grooved tube in one step and process micro-nano structures between the grooves.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] An expansion groove pipe expansion joint, comprising an expansion portion and a connecting portion;

[0010] The expansion part is in the shape of a truncated cone, and the side wall surface of the truncated cone is provided with a plurality of expansion teeth evenly spaced;

[0011] The expansion teeth extend from the bottom of the cone to the bottom of the cone, and the expansion teeth and the axis of the cone are located in the same plane;

[0012] The diameter of the upper bottom of the frustum is smaller than the inner diameter of the groove tube, and the diameter of the lower bottom of the frustum is larger than the inner diameter of the groove tube;

[0013] The connecting part and the extruding part are coaxially arranged, one end of the connecting part is used to be connected to the expansion rod, and the other end is connected to the lower bottom of the cone of the extruding part.

[0014] Furthermore, a frustum-shaped guide portion is provided at the front end of the extrusion portion. The guide portion is connected to the upper bottom of the frustum and is coaxially arranged with the extrusion portion.

[0015] Furthermore, an angle of 30-60° is formed between the side wall of the guide portion and the axis of the expansion portion.

[0016] Furthermore, the difference between the bottom diameter of the truncated cone and the inner diameter of the grooved tube is 0.1-0.3 mm.

[0017] Furthermore, the number of expansion teeth is 30-180.

[0018] Furthermore, the height of the expansion teeth is 0.1-0.2 mm.

[0019] Furthermore, the expansion teeth are provided with arc-shaped tooth tops, and the included angle of the arc-shaped tooth tops is 20-40 degrees.

[0020] Furthermore, the expansion part is made of chromium-tungsten-manganese steel, 440c or 4cr13.

[0021] Furthermore, the connecting portion is threadedly connected to the extrusion portion.

[0022] A grooved pipe processing method adopts an expansion head for an extruded grooved pipe, comprising the following steps:

[0023] Fix the metal smooth tube to be processed so that it coincides with the axis of the expansion rod, install the expansion head on the expansion rod through the connecting part, and use the expansion rod to drive the expansion head to make relative linear motion in the metal smooth tube. As the expansion rod is continuously fed, the extrusion and expansion teeth contact the inner wall of the metal smooth tube and expand. Multiple evenly spaced expansion teeth squeeze and expand multiple spaced grooves in the inner wall of the metal smooth tube, and form a spike structure composed of multiple sequentially spliced ​​grooves between the grooves.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] During operation, the metal tube to be added is fixed so that it coincides with the axis of the expansion rod. The expansion head is installed on the expansion rod through the connection part, and the tube expander is started to push the expansion rod and the metal tube to move relative to each other. Since the expansion part of the expansion head is in the shape of a truncated cone, the surface of the side wall of the truncated cone is provided with a plurality of evenly spaced expansion teeth. The diameter of the upper bottom of the truncated cone is smaller than the inner diameter of the groove tube, and the diameter of the lower bottom of the truncated cone is larger than the inner diameter of the groove tube. As the expansion rod is continuously fed, the expansion teeth begin to contact the inner wall of the metal tube and expand. The multiple evenly spaced expansion teeth squeeze out a plurality of spaced grooves in the inner wall of the metal tube, and the axis of the groove is parallel to the axis of the expansion head. Due to the squeezing of adjacent expansion teeth and the lack of external mold restrictions on the outside of the metal tube, a spike structure composed of multiple sequentially spliced ​​structures will be formed between the final formed grooves. This spike structure forms a micro-nano structure that can improve the phase change efficiency of the working medium, thereby effectively improving the performance of the heat pipe heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural schematic diagram of an expansion head for an extruded grooved tube.

[0027] Figure 2 This is a structural schematic diagram of the expansion teeth of an expansion grooved tube expansion head.

[0028] Figure 3 It is a structural schematic diagram of the extrusion part and the guide part.

[0029] Figure 4 This is a structural schematic diagram of the connection part of an expansion groove pipe expansion head.

[0030] Figure 5 Schematic diagram of the structure of the grooved tube spike structure formed by processing.

[0031] Figure 6 Schematic diagram of the tube expansion process.

[0032] In the picture:

[0033] 1- guide part, 2- expansion part, 3- connection part, 4- expansion tooth, 5- internal thread, 6- tooth side wall, 7- arc-shaped tooth top, 8- groove, 9- spike structure, 10- metal light tube. DETAILED DESCRIPTION

[0034] The present invention is described in further detail below.

[0035] like Figure 1-Figure 5 As shown, an expansion groove pipe expansion head includes a guide part 1, an expansion part 2 and a connecting part 3. The expansion part 2 is evenly distributed with multiple rows of expansion teeth 4. The connecting part 3 of the expansion head is connected to the expansion rod through an internal thread 5 to provide an expansion force for the expansion head.

[0036] Furthermore, the guide portion 1 of the expansion head is in a frustum shape to ensure that the expansion head can smoothly enter the metal smooth tube 10 and provide centripetal positioning. The side wall of the frustum forms an angle with the axis of the expansion head, and the angle is preferably 60°.

[0037] Furthermore, the diameter of the bottom of the cone of the expanding portion 2 of the expansion head is comparable to the inner diameter of the metal smooth tube 10 to be processed, and can also be slightly larger than the inner diameter of the metal smooth tube 10 to achieve the expansion effect. The expansion margin is preferably 0.2 mm.

[0038] Furthermore, the multiple extrusion teeth 4 of the expansion head are evenly distributed on the side wall surface of the cone of the expansion part 2, each extrusion tooth 4 is in the same plane as the axis of the expansion head, and the number of the extrusion teeth 4 is preferably 90.

[0039] Furthermore, the height of the expanding tooth 4 of the expanding head is preferably 0.15 mm. The structure of the expanding tooth 4 includes a tooth side wall 6 and an arc-shaped tooth top 7. The angle between the tooth side wall 6 and the symmetry axis of the expanding tooth 4 is preferably 30°, and the angle between the arc-shaped tooth top 7 is preferably 30°. During processing, the main force-bearing part is the arc-shaped tooth top 7.

[0040] Furthermore, the connection portion 3 of the expansion head is provided with an internal thread 5 to be connected to the expansion rod to obtain an expansion thrust. The length of the internal thread 5 is preferably 10 mm to ensure that the expansion head and the expansion rod are coaxial.

[0041] Furthermore, the guide portion 1 and the extrusion portion 2 of the expansion head are preferably made of a material with high hardness and wear resistance, preferably chromium-tungsten-manganese steel. The connection portion 3 is made of a lower hardness material, such as high-speed steel. The two are welded together.

[0042] Furthermore, the processing method of the expansion head is selected to be wire cutting, and the surface accuracy of the expansion part 2 and the guide part 1 is preferably Ra0.25, while the surface accuracy of the connecting part 3 is Ra3.2.

[0043] Furthermore, a plurality of spike structures 9 arranged in sequence are formed on both sides of the extruded groove 8. When the groove 8 tube is used in the heat exchange field, the micro-nano structure formed by the spike structure 9 helps to enhance the heat exchange capacity.

[0044] like Figure 6 As shown, a grooved pipe processing method adopts an expansion grooved pipe expansion head, comprising the following steps:

[0045] Fix the metal smooth tube 10 to be processed so that it coincides with the axis of the expansion rod, install the expansion head on the expansion rod through the connecting part 3, and use the expansion rod to drive the expansion head to make relative linear motion in the metal smooth tube 10. As the expansion rod is continuously fed, the extrusion and expansion teeth 4 contact the inner wall of the metal smooth tube 10 and expand. Multiple evenly spaced expansion teeth 4 extrude multiple spaced grooves 8 in the inner wall of the metal smooth tube 10, and form a plurality of spike structures 9 spliced ​​in sequence between the grooves 8.

[0046] Taking the processing of copper light tubes as an example, the specific steps include:

[0047] (1) Cut the copper tube to be processed, straighten it and clean it.

[0048] (2) Expand one end of the copper tube to facilitate the entry of the expansion head and avoid colliding with the tube wall, which may cause damage to the expansion head and the pipe fitting.

[0049] (3) Fix the copper tube to ensure that it coincides with the axis of the expansion rod.

[0050] (4) Install the expansion head onto the expansion rod using threaded fastening.

[0051] (5) Apply lubricating oil.

[0052] (6) Start the tube expander, push the expansion rod and the light tube to move relative to each other, observe the working status, squeeze out the groove 8, and form multiple spike structures 9 between the grooves 8 to obtain the processed copper groove 8 tube.

[0053] With this processing method, there is no need for additional external molds, and the processing process does not require diameter reduction treatment. It can be directly extruded and formed in one step. The process is simple and convenient, and micro-nano structures can be processed between the grooves 8, effectively improving the phase change efficiency of the working medium in the groove 8 tube and improving the performance of the heat pipe exchanger.

[0054] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A grooved pipe processing method, characterized in that: A kind of expansion head for extrusion and expansion grooved pipe is adopted, and the expansion head includes an extrusion part and a connection part; The expansion part is in the shape of a truncated cone, and the side wall surface of the truncated cone is provided with a plurality of expansion teeth evenly spaced; The expansion teeth extend from the bottom of the cone to the bottom of the cone, and the expansion teeth and the axis of the cone are located in the same plane; The diameter of the upper bottom of the frustum is smaller than the inner diameter of the groove tube, and the diameter of the lower bottom of the frustum is larger than the inner diameter of the groove tube; The connecting portion and the extruding portion are coaxially arranged, one end of which is used to be connected to the expansion rod, and the other end of which is connected to the bottom of the cone of the extruding portion; The processing method comprises the following steps, Fix the metal smooth tube to be processed so that it coincides with the axis of the expansion rod, install the expansion head on the expansion rod through the connecting part, and use the expansion rod to drive the expansion head to make relative linear motion in the metal smooth tube. As the expansion rod is continuously fed, the extrusion and expansion teeth contact the inner wall of the metal smooth tube and expand. Multiple evenly spaced expansion teeth squeeze and expand multiple spaced grooves in the inner wall of the metal smooth tube, and form multiple spike structures spliced ​​in sequence between the grooves.

2. The processing method according to claim 1, characterized in that: A frustum-shaped guiding portion is provided at the front end of the squeezing and expanding portion. The guiding portion is connected to the upper bottom of the frustum and is coaxially arranged with the squeezing and expanding portion.

3. The processing method according to claim 2, characterized in that: An included angle of 30-60° is formed between the side wall of the guide portion and the axis of the extrusion portion.

4. The processing method according to claim 1, characterized in that: The difference between the bottom diameter of the truncated cone and the inner diameter of the grooved tube is 0.1-0.3 mm.

5. The processing method according to claim 1, characterized in that: The number of expansion teeth is 30-180.

6. The processing method according to claim 1, characterized in that: The height of the expansion teeth is 0.1-0.2mm.

7. The processing method according to claim 1, characterized in that: The expansion teeth are provided with arc-shaped tooth tops, and the included angle of the arc-shaped tooth tops is 20-40°.

8. The processing method according to claim 1, characterized in that: The expansion part is made of chromium tungsten manganese steel, 440c or 4cr13.

9. The processing method according to claim 1, characterized in that: The connecting portion is threadedly connected to the extrusion portion.

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