Extrusion forming die for single-axis symmetric uniform-section long-axis finned tube

Abstract

The utility model discloses a single-axis symmetric uniform-section long-axis finned tube extrusion forming die which comprises an extrusion container, a die holder, a die middle pad and a die tail pad which are sequentially assembled, and a core rod is arranged in the extrusion container in a sliding mode. An extrusion die and a die support are fixedly arranged in the die holder; the core rod comprises a core rod needle point and a core rod matrix; the core rod needle point is in threaded connection with the front end of the core rod matrix; the central point of the extrusion die is close to the fin, the position, corresponding to the center of the single-finned-tube circular tube, of the extrusion die cavity is far away from the fin, the core rod parent body, the extrusion die and the die support are coaxial, and the axis is a D axis; the needle point of the core rod, the position, corresponding to the circular tube of the single finned tube, of the extrusion die cavity and the position, corresponding to the circular tube of the single finned tube, of the die supporting cavity are coaxial, and the shaft is an E shaft; and the area of the upper cavity and the area of the lower cavity enclosed by the core rod matrix and the extrusion die are matched with each other. According to the utility model, the quantity of blanks in the upper cavity and the lower cavity at the extrusion end can be ensured to be similar, so that the flow velocity of the blanks is balanced, the straightness of a single-fin formed pipe is improved, and the device is suitable for the extrusion forming industry.

Description

Technical Field

[0001] The utility model belongs to the field of hot extrusion forming, in particular to a uniaxial symmetrical long-axis fin tube extrusion forming die. Background Art

[0002] Finned tube is a heat exchange element, that is, fins are added to the surface of a circular heat exchange tube to increase the outer surface area or inner surface area of ​​the heat exchange tube, thereby improving the heat exchange efficiency. At present, the production of finned tubes mostly adopts hot extrusion process. The extrusion principle is: the metal billet in a high temperature state flows through a specific cavity composed of a mold under the action of three-dimensional compressive stress to form. This process gives full play to the plasticity of the material, which is conducive to the production of difficult-to-deform alloy tubes. The mold structure is simple, the production process is short, the product surface quality is good, and the dimensional accuracy is high.

[0003] The traditional hot extrusion die structure is as follows: Figure 1 As shown, it includes an extrusion barrel 8, which includes an inner liner 803, a middle liner 802 and an outer shell 801 assembled in an interference fit manner. An extrusion rod 13 is slidably arranged at the center line of the extrusion barrel 8, an extrusion gasket 9 is arranged at the front end of the extrusion rod 13, and a core rod 12 is slidably arranged at the center line of the extrusion rod 13. The core rod 12 is used to size the center hole of the blank, and the rear end of the core rod 12 is connected to the core rod support rod 11 by a threaded manner through a core rod connector 10; a die base 1, a die center pad 2 and a die tail pad 3 are fixed to the front end of the extrusion barrel 8 in sequence, and an extrusion die 4 is arranged inside the die base 1 (see the specific structure for details). Figure 2 (a)) and mold support 6 (for specific structure, see Figure 2 (b)), an extrusion cavity 5 is formed between the core rod 12 and the inner liner 803 of the extrusion cylinder 8, and a lubricating glass pad is placed at one end of the extrusion die 4 close to the extrusion cavity 5. Figure 1 The glass pad is not shown. The extrusion principle of the die is as follows: a solid metal blank is heated and placed in the extrusion cavity 5, the core rod support rod 11 is pushed forward so that the core rod 12 pierces the solid metal blank, and after the piercing, the extrusion rod 13 is pushed forward again, and the extrusion gasket 9 is pushed by the extrusion rod 13 to apply force to the blank to deform it, and finally the required pipe is extruded from the front end.

[0004] Since the center of the core rod 12, the center of the extrusion die 4, and the center of the die support 6 in the above-mentioned hot extrusion forming die are all located on the center line of the extrusion barrel 8, it is suitable for producing a biaxially symmetrical long-axis fin tube with equal cross-section (also called a double-fin tube 16). Figure 3(a) is a type of double-finned tube 16. The outer circumference of the hollow circular tube in the longitudinal section is provided with upper and lower trapezoidal blocks, and the length of the trapezoidal blocks is the same as the length of the circular tube. Equal cross-section means that the shape and area of ​​the longitudinal section at any position of the tube are the same. Biaxial symmetry means that the tube has two symmetry axes, horizontal and vertical, so that the tube is symmetrical in the upper and lower parts and in the left and right parts. When forming this type of tube, the upper cavity area S1 and the lower cavity area S2 surrounded by the core rod 12 and the extrusion die 4 are also symmetrical in the upper and lower parts, see Figure 3 (b), so that the amount of billet flowing through S1 and S2 during the extrusion process is the same, so that under the action of the extrusion gasket 9, the flow speed of the metal billet is balanced everywhere, and the surface quality of the final formed pipe is good.

[0005] However, for a uniaxially symmetrical long-axis finned tube (also called a single-finned tube 15), its structure is as follows Figure 4 As shown in (a), from the longitudinal section, there is only one trapezoidal block set on the outer circumference of the circular tube, so the tube has only one vertical symmetry axis and is bilaterally symmetrical about the symmetry axis. Figure 1 When extruding the die in the mold, the shape of the extrusion die 4 needs to be adjusted to the shape of a single fin tube, but if Figure 4 As shown in (b), at this time, the upper cavity area S1' surrounded by the core rod 12 and the extrusion die 4 is larger than the lower cavity area S2', and the position of the billet in the cavity is fixed. Then, during extrusion, the lower cavity area S2' is small, but the corresponding billet amount is too much, which is prone to material blockage; in addition, the cavity corresponding to S2' has a large amount of billet and a high extrusion flow rate, while the cavity corresponding to S1' has a slow billet extrusion flow rate, which makes the produced pipe easy to bend and has poor surface quality. Utility Model Content

[0006] In order to solve the above deficiencies in the prior art, the utility model aims to provide a uniaxially symmetrical long-axis finned tube extrusion forming die, so as to achieve the purpose of balancing the flow rate of the blank in various parts of the cavity during the extrusion forming of the uniaxially symmetrical long-axis finned tube, thereby ensuring the straightness of the formed tube.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0008] A uniaxial symmetrical long-axis finned tube extrusion forming die comprises an extrusion barrel, an extrusion rod is slidably arranged at the center line of the extrusion barrel, an extrusion gasket is arranged at the front end of the extrusion rod, a core rod is slidably arranged at the center line of the extrusion rod, the extrusion gasket is sleeved on the outer diameter of the core rod, and the rear end of the core rod is connected to the core rod support rod in a threaded manner through a core rod connector; a die seat, a die middle pad and a die tail pad are fixedly arranged at the front end of the extrusion barrel in sequence, an extrusion die and a die support are fixedly arranged inside the die seat, the extrusion die is hollow inside to form an extrusion die cavity, a glass pad is arranged at the extrusion end of the extrusion die, the die support is hollow inside to form a die support cavity, the shape of the extrusion die cavity is adapted to the shape of the die support cavity, the die seat comprises a die seat outer ring and a die seat inner ring connected by clamping, the extrusion die and the die support are fixed inside the die seat inner ring, and the shape and size of the extrusion die cavity are adapted to the outer periphery of the single-finned tube;

[0009] The mandrel includes a mandrel needle tip and a mandrel body. The mandrel body is connected to the mandrel support rod by a threaded manner through a mandrel connector. The mandrel needle tip is threadedly connected to the front end of the mandrel body. The outer diameter of the mandrel needle tip is adapted to the inner diameter of the single-fin tube.

[0010] The center point of the extrusion die is arranged close to the fin, the position on the extrusion die cavity corresponding to the center of the single-fin tube is arranged far away from the fin, the mandrel mother body, the extrusion die and the die support are coaxial, and the axis is the D axis; the mandrel needle tip, the position of the extrusion die cavity corresponding to the single-fin tube, and the position of the die support cavity corresponding to the single-fin tube are coaxial, and the axis is the E axis, the D axis is parallel to the E axis, and the horizontal plane where the D axis is located is used as the dividing line. The upper cavity area and the lower cavity area surrounded by the mandrel mother body and the extrusion die are adapted to each other.

[0011] As a limitation of the utility model: the mandrel needle tip comprises a needle tip working section, a needle tip transition section and a needle tip external thread section which are arranged in sequence in the horizontal direction, the diameter of the needle tip working section is smaller than the diameter of the mandrel body, the needle tip transition section is a smooth transition structure, the maximum diameter of the needle tip transition section is equal to the diameter of the mandrel body, and the minimum diameter of the needle tip transition section is equal to the diameter of the needle tip working section;

[0012] The needle tip external thread section is threadedly connected to the front end of the core rod mother body, the needle tip transition section is coaxial with the core rod mother body, and the needle tip working section is coaxial with the position of the single fin tube round tube corresponding to the extrusion mold cavity.

[0013] As a further definition of the utility model: the needle tip transition section includes a straight portion and a transition portion, the straight portion is arranged close to the core rod body, and the diameter of the straight portion is equal to the diameter of the core rod body; the transition portion is arranged close to the needle tip working section, and the longitudinal cross-section of the transition portion at any position is circular, the end of the transition portion close to the straight portion is the end with the largest diameter, and the end of the transition portion close to the needle tip working section is the end with the smallest diameter.

[0014] As another limitation of the present utility model: the axial thickness of the extrusion die is 35mm~40mm, the angle of the cone surface is 24°, the extrusion die cavity includes a drainage arc surface, an intermediate sizing zone and an outlet anti-conical zone, the length of the intermediate sizing zone is 10mm~20mm, the length of the outlet anti-conical zone is 5mm~10mm, and the shape of the intermediate sizing zone is consistent with the external contour of the single-fin tube.

[0015] As a further limitation of the present invention: the size of the die support cavity is 10 mm to 20 mm larger than the size of the extrusion die cavity.

[0016] As a further limitation of the utility model: a first positioning hole is also provided on the extrusion die, a second positioning hole is provided on the die support at a position corresponding to the first positioning hole, and positioning pins for fastening the extrusion die and the die support together are passed through the first positioning hole and the second positioning hole.

[0017] As another limitation of the present invention: the cone angle between the inner ring of the die base and the extrusion die is 24°, and the smallest diameter end is arranged close to the extrusion end of the extrusion die, and the cone angle between the inner ring of the die base and the extrusion barrel is 59° to 61°.

[0018] Due to the adoption of the above technical solution, the utility model has the following beneficial effects compared with the prior art:

[0019] The utility model is an improvement on the extrusion die in the prior art, and the specific improvement lies in adjusting the structures of the core rod, the extrusion die and the die support, and moving the position of the center of the round tube of the formed tube on the extrusion die cavity body a certain distance in the direction away from the fin (moving downward from point e to point g), which is equivalent to moving the extrusion die cavity body as a whole downward, so that the area S1' of the upper cavity with fins and the area S2' of the lower cavity without fins are nearly equal with the horizontal plane where the D axis is located as the dividing line; accordingly, the center of the needle tip working section in the core rod needle tip and the position of the center of the single-fin tube round tube on the extrusion die cavity body are also moved downward by a certain distance, ensuring that the needle tip working section and the position of the single-fin tube round tube of the extrusion die cavity body are coaxial with the position of the single-fin tube round tube of the die support cavity body, so that the amount of blanks located in the upper cavity and the lower cavity during the extrusion process is the same, avoiding the problem of material suffocation or bending of the formed tube due to the small area of ​​the lower cavity but a large amount of blanks.

[0020] In summary, when the utility model is used to extrude a uniaxially symmetrical long-axis finned tube with a uniform cross-section, it can ensure that the amount of blank in the upper cavity and the lower cavity surrounded by the core rod matrix at the extrusion end and the extrusion die is similar, so that the flow rate of the blank is balanced and the straightness of the formed tube is improved; the utility model is suitable for the extrusion forming industry and is used to form a uniaxially symmetrical long-axis finned tube with a uniform cross-section. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Figure 1 It is a structural schematic diagram of an extrusion forming die in the prior art;

[0023] Figure 2 (a) is a schematic longitudinal section diagram of an extrusion die in the prior art, and (b) is a schematic longitudinal section diagram of a die support in the prior art;

[0024] Figure 3 (a) is a schematic diagram of a longitudinal section of a double-finned tube to be formed, and (b) is a schematic diagram of the structure of a forming cavity surrounded by an extrusion die and a core rod when extruding the double-finned tube to be formed;

[0025] Figure 4 (a) is a schematic diagram of a longitudinal section of a single-fin tube to be formed, and (b) is a schematic diagram of the structure of a forming cavity surrounded by an extrusion die and a core rod when extruding the single-fin tube to be formed;

[0026] Figure 5 It is a schematic diagram of the structure of an embodiment of the utility model;

[0027] Figure 6 It is a schematic structural diagram of a molding cavity surrounded by an extrusion die and a core rod matrix in an embodiment of the utility model;

[0028] Figure 7 This is a schematic diagram of the structure of the core rod in the embodiment of the utility model;

[0029] Figure 8 (a) is a schematic diagram of the structure of the core rod needle tip in the embodiment of the utility model, and (b) is a cross-sectional view along the BB direction in (a);

[0030] Fig. 9 (a) is a schematic diagram of the structure of the extrusion die in the embodiment of the utility model, (b) is a cross-sectional view along the AA line in (a), and (c) is a schematic diagram of the three-dimensional structure of the extrusion die in the embodiment of the utility model;

[0031] Fig.10 (a) is a schematic diagram of the main structure of the mold support in the embodiment of the utility model, (b) is a schematic diagram of the three-dimensional structure of the mold support in the embodiment of the utility model, and (c) is a schematic diagram of the partial structure of the mold support in the embodiment of the utility model;

[0032] Fig.11 (a) is a schematic longitudinal section view of the inner ring of the die base in the embodiment of the present utility model, (b) is a schematic three-dimensional structure view of the inner ring of the die base in the embodiment of the present utility model, and (c) is a schematic partial structure view of the inner ring of the die base in the embodiment of the present utility model;

[0033] Fig.12(a) is a schematic longitudinal section diagram of the outer ring of the mold base in the embodiment of the utility model, and (b) is a schematic diagram of the partial structure of the outer ring of the mold base in the embodiment of the utility model;

[0034] Fig.13 This is a schematic diagram of the structure of the single fin tube finally formed in the embodiment of the utility model;

[0035] Fig.14 It is a schematic diagram of the structure before and after the extrusion die cavity moves downward in an embodiment of the utility model.

[0036] In the figure: 1-die base, 101-die base outer ring, 1011-die base outer ring boss, 102-die base inner ring, 1021-die base inner ring concave;

[0037] 2-mold center pad, 3-mold tail pad;

[0038] 4-extrusion die, 401-drainage arc surface, 402-first positioning hole, 403-extrusion die cavity, 4031-arc area, 4032-fin area;

[0039] 5-Extrusion cavity;

[0040] 6-mold support, 601-second positioning hole, 602-mold support cavity;

[0041] 7- Glass mat;

[0042] 8-extrusion cylinder, 801-shell, 802-middle lining, 803-inner lining;

[0043] 9-Extrusion gasket;

[0044] 10- mandrel connecting piece, 11- mandrel supporting rod;

[0045] 12-mandrel, 121-mandrel needle tip, 1211-needle tip working section, 1212-needle tip transition section, 12121-straight portion, 12122-transition portion, 1213-needle tip external thread section, 122-mandrel mother body, 1221-mandrel mother body external thread section;

[0046] 13-extruded rod, 14-blank, 15-single fin tube, 16-double fin tube, 17-horizontal plane where D axis is located. DETAILED DESCRIPTION

[0047] The preferred embodiment of the utility model is described below in conjunction with the accompanying drawings. It should be understood that the uniaxial symmetrical equal cross-section long-axis fin tube extrusion forming die described here is a preferred embodiment, which is only used to illustrate and explain the utility model and does not constitute a limitation of the utility model.

[0048] The directional terms or positional relationships such as "upper", "lower", "front", and "back" described in the embodiments are based on the drawings in the specification of the utility model. Figure 1 The orientation relationship is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the content protected by the present invention.

[0049] This embodiment includes an extrusion barrel 8, an extrusion rod 13 is slidably arranged at the center line of the extrusion barrel 8, an extrusion gasket 9 is arranged at the front end of the extrusion rod 13, a core rod 12 is slidably arranged at the center line of the extrusion rod 13, the extrusion gasket 9 is sleeved on the outer diameter of the core rod 12, and the rear end of the core rod 12 is connected to the core rod support rod 11 by threading through the core rod connector 10; the front end of the extrusion barrel 8 is fixed with a die base 1, a die center pad 2 and a die tail pad 3 in sequence, the die base 1 is fixed with an extrusion die 4 and a die support 6, the extrusion die 4 is hollow inside to form an extrusion die cavity 403, the extrusion end of the extrusion die 4 is provided with a glass pad 7, the die support 6 is hollow inside to form a die support cavity 602, the shape of the extrusion die cavity 403 is adapted to the shape of the die support cavity 602, and the shape and size of the extrusion die cavity 403 are adapted to the outer periphery of the formed pipe, and this part of the content is the prior art. The shape and size of the extrusion die cavity in this embodiment are the same as the outer contour of the single-fin tube.

[0050] This embodiment finally forms a uniaxially symmetrical long-axis fin tube with equal cross-section, that is, a single-fin tube 15, see Figure 4 (a) Fig.13 , the single fin is located above the circular tube, such as Figure 4 As shown in (b), the C axis is the horizontal symmetry axis of the extrusion die 4, and the C axis is the dividing line. The upper cavity has fins, so the upper cavity area S1' is larger than the lower cavity area S2', and the amount of billet flowing through the upper cavity and the lower cavity is similar. Then, there is too much billet 14 in the lower cavity with a smaller area, and the flow rate is fast, resulting in bending of the formed tube.

[0051] In this embodiment, the structure of the core rod 12, the extrusion die 4 and the die support 6 is improved, and the extrusion die cavity 403 is moved downward by a certain distance h as a whole. Fig.14 , Fig.14 The middle dashed line represents the position of the extrusion die cavity 401 before moving downward. Figure 6 As shown, in the cavity surrounded by the core rod mother body 122 after downward movement and the extrusion die 4, the horizontal plane 17 where the D axis is located is used as the dividing interface, and the upper cavity area S1' and the lower cavity area S2' are adapted. Adaptation here means that S1' and S2' are almost equal, so the amount of billet flowing through the upper cavity and the lower cavity is similar, the flow rate of the billet 14 is balanced during extrusion, and the straightness of the final formed pipe is higher.

[0052] The specific improvements of the core rod 12, the extrusion die 4, and the die support 6 are as follows:

[0053] 1. Mandrel 12;

[0054] like Figure 5 , Figure 7 , Figure 8 As shown, the mandrel 12 includes a mandrel needle tip 121 and a mandrel body 122; the longitudinal section of the mandrel body 122 is circular, and the mandrel body 122 is threadedly connected to the mandrel connector 10. Specifically, a mandrel body external thread section 1221 is provided at the rear end of the mandrel body 122 to achieve threaded connection with the mandrel connector 10. The mandrel needle tip 121 is threadedly connected to the front end of the mandrel body 122, and the mandrel needle tip 121 is integrally formed, including a needle tip working section 1211, a needle tip transition section 1212, and a needle tip external thread section 1213 arranged in sequence along the horizontal direction, where the horizontal direction refers to the front and rear directions, and a mandrel body internal thread section is provided at the front end of the mandrel body 122 corresponding to the needle tip external thread section 1213. The needle tip working section 1211 determines the internal contour of the single fin tube 15. In other words, the outer diameter of the core rod needle tip 121 is adapted to the inner diameter of the formed fin tube. Adaptation here means that the outer diameter of the needle tip working section 1211 is equal to the inner diameter of the formed fin tube, that is, the needle tip working section 1211 is coaxial with the circular tube position of the extruded single fin tube 15.

[0055] like Figure 7 , Figure 8 As shown, the diameter of the needle tip working section 1211 is smaller than the diameter of the core rod matrix 122, and the central axis E of the needle tip working section 1211 is lower than the central axis D of the core rod matrix 122 by a certain distance h, and in this embodiment, h=12 mm.

[0056] The needle tip transition section 1212 is a smooth transition structure. The needle tip transition section 1212 includes a straight portion 12121 and a transition portion 12122. The straight portion 12121 is arranged close to the core rod matrix 122. In this embodiment, the straight portion 12121 is a cylindrical structure, coaxial with the core rod matrix 122, and the diameter of the straight portion 12121 is equal to the diameter of the core rod matrix 122; the transition portion 12122 is arranged close to the needle tip working section 1211, and the transition portion 12122 is a truncated cone structure. In other words, the longitudinal section of the transition portion 12122 at any position is circular, and the end of the transition portion 12122 close to the straight portion 12121 is the end with the largest diameter, and the largest diameter is equal to the diameter of the mandrel matrix 122, and the end of the transition portion 12122 close to the needle tip working section 1211 is the end with the smallest diameter, and the smallest diameter is equal to the diameter of the needle tip working section 1211. The transition portion 12122 can ensure that the blank 14 flows more smoothly from the mandrel matrix 122 to the mandrel needle tip 121. Of course, the needle tip transition section 1212 can be set as a truncated cone structure as a whole, under which the largest diameter end of the needle tip transition section 1212 is connected to the mandrel matrix 122, and the smallest diameter end of the needle tip transition section 1212 is connected to the needle tip working section 1211.

[0057] 2. Extrusion die 4;

[0058] like Figure 5 , Fig. 9 , Fig.13 As shown, the shape and size of the extrusion die cavity 403 are compatible with the outer periphery of the single fin tube 15. Here, the adaptation means that the shape and size of the extrusion die cavity 403 are consistent with the outer contour of the single fin tube 15; the axial thickness of the extrusion die 4 in this embodiment is 35mm-40mm, and 35mm, 38mm, and 40mm can be selected. In this embodiment, it is 38mm. The outer edge of the extrusion die 4 is circular, and the extrusion end of the extrusion die 4 is a conical surface. The angle α of the conical surface is 24°, see Fig. 9 (b). The extrusion die 4 is provided with a flow-guiding arc surface 401, an intermediate sizing area and an outlet anti-conical area, see Fig. 9 (c) The length of the intermediate sizing zone is 10 mm to 20 mm. This parameter setting can improve the service life of the extrusion die 4. Otherwise, if the length of the intermediate sizing zone is too short, the die will be deformed after several extrusions; if the length of the intermediate sizing zone is too long, the friction is large, which is not conducive to metal flow. The length of the outlet anti-cone zone is 5 mm to 10 mm. The above parameters are set together to improve the surface quality and dimensional accuracy of the formed single-fin tube 15.

[0059] The structure of the extrusion die 4 is as follows Fig. 9 As shown in (a), the hollow area inside the extrusion die 4 (i.e., the extrusion die cavity 403) includes an arc area 4031 and a fin area 4032. The arc area 4031 corresponds to the circular tube portion of the single-fin tube 15. Fig. 9 The auxiliary line below the fin in (a) is to make the arc area 4031 form a complete circle, so as to facilitate the clear observation of the center point of the arc area 4031. The center point of the arc area 4031 corresponds to the center of the inner circle of the formed fin tube. In this embodiment, the center point g of the arc area 4031 is lower than the center point e of the extrusion die 4 by a certain distance h=12mm. Under this structure, Figure 6 As shown, with the horizontal plane 17 where the D axis is located as the dividing interface, the upper cavity area S1' and the lower cavity area S2' surrounded by the core rod matrix 122 and the extrusion die 4 are almost equal, avoiding the problem of material blockage or bending of the formed tube due to the small lower cavity area but large amount of blanks during the extrusion process.

[0060] 3. Mould support 6;

[0061] like Figure 5 , Fig. 9 , Fig.10As shown, the die support 6 is arranged at the front end of the extrusion die 4, and the contour shape of the die support cavity 602 is adapted to the extrusion die cavity 403. Adaptation here means that the two have the same shape, and the die support cavity 602 is coaxial with the extrusion die cavity 403, that is, the die support cavity 602 is also moved down by h=12mm, but the size of the die support cavity 602 is 10mm~20mm larger than the size of the extrusion die cavity 403, preferably, 16mm larger, to prevent the single-fin tube 15 from being scratched when passing through the die support 6 after being extruded from the extrusion die 4.

[0062] The extrusion die 4 is also provided with two first positioning holes 402 , and the die support 6 is provided with a second positioning hole 601 at a position corresponding to the first positioning hole 402 . The positioning pins penetrate the first positioning holes 402 and the second positioning holes 601 to fasten the extrusion die 4 and the die support 6 together.

[0063] It should be noted that the extrusion die 4 is described in detail as a representative: Figure 6 , 9 As shown in Figure 14, the center point of the extrusion die 4 is point e, and the center point of the arc area 4031 on the extrusion die cavity 403 is point g. Point g is lower than point e, and the spacing is h=12mm. The "lower than" here only represents the orientation relationship of this embodiment. If the fin is located below, then point g should be 12mm higher than point e. As long as the center point of the extrusion die 4 is close to the fin and the center point of the arc area 4031 on the extrusion die cavity 403 is far away from the fin, the upper cavity area S1' and the lower cavity area S2' surrounded by the core rod mother 122 and the extrusion die 4 with the horizontal plane 17 where the D axis is located are taken as the dividing line, can be approximately equal. In this way, it can be ensured that the amount of billet flowing through the upper cavity and the lower cavity is similar, the flow rate of the billet 14 is balanced during extrusion, and the straightness of the final formed pipe is high. At the same time, the core rod mother body 122, the extrusion die 4 and the die support 6 are coaxial, and the axis is the D axis. The improved needle tip working section 1211 and the position of the extrusion die cavity 403 corresponding to the single fin tube 15 round tube (i.e., the arc area 4031 of the extrusion die cavity 403) are coaxial with the position of the single fin tube 15 round tube of the die support cavity 602 (i.e., the arc area of ​​the die support cavity 602), and the axis is the E axis. The D axis is parallel to the E axis, and the E axis is lower than the D axis by h=12mm.

[0064] 4. Die base 1;

[0065] This embodiment also makes further improvements to the mold base 1 of the prior art, such as Figure 5 , Fig.11 , Fig.12 As shown, the die base 1 includes a die base outer ring 101 and a die base inner ring 102 which are connected by clamping, and the extrusion die 4 and the die support 6 are fixedly arranged inside the die base inner ring 102. The structure of the die base inner ring 102 is as shown in FIG. Fig.11 As shown, the structure of the mold base outer ring 101 is as follows Fig.12As shown, the die base inner ring 102 is provided with a die base inner ring concave platform 1021, and the die base outer ring 101 is provided with a corresponding die base outer ring convex platform 1011. Because the interior of the die base 1 is easily damaged by the extrusion force for a long time during the extrusion process, the die base 1 is set as a split structure in this embodiment, and the die base inner ring 102 can be replaced separately to reduce costs.

[0066] like Figure 5 , Fig.11 As shown in (a), the cone angle α' at the assembly of the die base inner ring 102 and the extrusion die 4 is 24°, and the minimum diameter end is set close to the extrusion end of the extrusion die 4. The extrusion end refers to the end when the billet just contacts the extrusion die 4 at the initial stage of extrusion. The cone angle β at the assembly of the die base inner ring 102 and the extrusion cylinder 8 is 59° to 61°, and 59°, 60°, and 61° can be selected. In this embodiment, it is 60°. Under this parameter, the assembly effect between the various components is better, and the later extrusion is more efficient.

[0067] When using this embodiment, the solid metal blank 14 is heated to a certain temperature (for example, 1120°C to 1180°C), coated with glass powder lubricant, and loaded into the extrusion cylinder 8. The core rod support rod 11 is pushed forward so that the needle tip working section 1211 perforates the solid metal blank 14. After perforation, it is extruded, and the extrusion rod 13 is used to push the extrusion gasket 9 and the blank 14 forward to the front end of the extrusion die 4. After the blank 14 contacts the glass pad 7 close to the front end of the extrusion die 4, the extrusion rod 13 continues to push forward and applies pressure to the blank 14 through the extrusion gasket 9, first causing the blank 14 to undergo filling deformation and eliminating the gap between the outer circle of the blank 14 and the inner wall of the extrusion cylinder 8. Then the blank 14 is extruded into the cavity formed by the extrusion die 4 and the needle tip working section 1211. Since the upper cavity area S1' is almost equal to the lower cavity area S2', the amount of blank in the upper cavity is similar to that in the lower cavity, and the flow rate of the blank 14 is balanced, so that the required single-fin tube 15 with uniform wall thickness and high straightness is extruded.

[0068] It should be noted that the above is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiment, those skilled in the art can still modify the technical solutions recorded in the above embodiment or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A uniaxial symmetrical long-axis finned tube extrusion forming die, comprising an extrusion barrel, an extrusion rod is slidably arranged at the center line of the extrusion barrel, an extrusion gasket is arranged at the front end of the extrusion rod, a core rod is slidably arranged at the center line of the extrusion rod, the extrusion gasket is sleeved on the outer diameter of the core rod, and the rear end of the core rod is connected to the core rod support rod by a threaded manner through a core rod connector; a die seat, a die middle pad and a die tail pad are fixedly arranged at the front end of the extrusion barrel in sequence, an extrusion die and a die support are fixedly arranged inside the die seat, the extrusion die is hollow inside to form an extrusion die cavity, a glass pad is arranged at the extrusion end of the extrusion die, the die support is hollow inside to form a die support cavity, the shape of the extrusion die cavity is adapted to the shape of the die support cavity, and the characteristics are as follows: The die base comprises a die base outer ring and a die base inner ring which are connected by clamping, the extrusion die and the die support are fixed inside the die base inner ring, and the shape and size of the extrusion die cavity are adapted to the outer periphery of the single fin tube; The mandrel includes a mandrel needle tip and a mandrel body. The mandrel body is connected to the mandrel support rod by a threaded manner through a mandrel connector. The mandrel needle tip is threadedly connected to the front end of the mandrel body. The outer diameter of the mandrel needle tip is adapted to the inner diameter of the single-fin tube. The center point of the extrusion die is arranged close to the fin, the position on the extrusion die cavity corresponding to the center of the single-fin tube is arranged far away from the fin, the mandrel mother body, the extrusion die and the die support are coaxial, and the axis is the D axis; the mandrel needle tip, the position of the extrusion die cavity corresponding to the single-fin tube, and the position of the die support cavity corresponding to the single-fin tube are coaxial, and the axis is the E axis, the D axis is parallel to the E axis, and the horizontal plane where the D axis is located is used as the dividing line. The upper cavity area and the lower cavity area surrounded by the mandrel mother body and the extrusion die are adapted to each other.

2. The uniaxially symmetrical long-axis fin tube extrusion forming die according to claim 1 is characterized in that: The mandrel needle tip includes a needle tip working section, a needle tip transition section and a needle tip external thread section which are arranged in sequence in the horizontal direction. The diameter of the needle tip working section is smaller than the diameter of the mandrel mother body. The needle tip transition section is a smooth transition structure. The maximum diameter of the needle tip transition section is equal to the diameter of the mandrel mother body, and the minimum diameter of the needle tip transition section is equal to the diameter of the needle tip working section. The needle tip external thread section is threadedly connected to the front end of the core rod mother body, the needle tip transition section is coaxial with the core rod mother body, and the needle tip working section is coaxial with the position of the single fin tube round tube corresponding to the extrusion mold cavity.

3. The uniaxially symmetrical long-axis fin tube extrusion forming die according to claim 2 is characterized in that: The needle tip transition section includes a straight portion and a transition portion. The straight portion is arranged close to the core rod body, and the diameter of the straight portion is equal to the diameter of the core rod body; the transition portion is arranged close to the needle tip working section, and the longitudinal cross-section of the transition portion at any position is circular. The end of the transition portion close to the straight portion is the end with the largest diameter, and the end of the transition portion close to the needle tip working section is the end with the smallest diameter.

4. The uniaxially symmetrical uniform cross-section long-axis fin tube extrusion forming die according to any one of claims 1 to 3, characterized in that: The axial thickness of the extrusion die is 35mm-40mm, and the angle of the cone surface is 24°; the extrusion die is provided with a drainage arc surface, an intermediate sizing area and an outlet reverse cone area. The length of the intermediate sizing area is 10mm-20mm, the length of the outlet reverse cone area is 5mm-10mm, and the shape of the intermediate sizing area is consistent with the external contour of the single-fin tube.

5. The uniaxially symmetrical long-axis fin tube extrusion forming die according to claim 4 is characterized in that: The size of the die support cavity is 10 mm to 20 mm larger than that of the extrusion die cavity.

6. The uniaxially symmetrical long-axis fin tube extrusion forming die according to claim 5, characterized in that: The extrusion die is also provided with a first positioning hole, and the die support is provided with a second positioning hole at a position corresponding to the first positioning hole. Positioning pins for fastening the extrusion die and the die support together are penetrated through the first positioning hole and the second positioning hole.

7. The uniaxially symmetrical uniform cross-section long-axis fin tube extrusion forming die according to any one of claims 1-3, 5 and 6, characterized in that: The taper angle at the assembly point between the inner ring of the die base and the extrusion die is 24 degrees, and the minimum diameter end is arranged close to the extrusion end of the extrusion die. The taper angle at the assembly point between the inner ring of the die base and the extrusion barrel is 59 degrees to 61 degrees.

Images