GB2556820A

GB2556820A - Combined mold core for supercharged multichannel pipe divergent mold

Info

Publication number: GB2556820A
Application number: GB1804182.2A
Authority: GB
Inventors: Wang Yun; Yang Xiaming; Du Jinxing; Zhao Kangmei; Xu Zhenying; Ren Naifei; Lu Haijian; Wang Cuntang; Ren Xudong; Bai Yun
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2015-09-23
Filing date: 2015-10-10
Publication date: 2018-06-06
Anticipated expiration: 2035-10-10
Also published as: CN105149375B; CN105149375A; GB201804182D0; GB2556820B; WO2017049668A1

Abstract

A combined mold core for a supercharged multichannel pipe divergent mold, which relates to the field of micro-bore-size multichannel pipe preparation. The combined mold core comprises a mold core (1), a lower mold (3), and a lower mold supporting plate (6). A lower mold through hole (4) is formed n the center of the lower mold (3). The outer contour of the lower mold supporting plate (6) is same as the shape and the size of the lower mold through hole (4), and the thickness of the lower mold supporting plate (6) is smaller than that of the lower mold (3), and the lower mold supporting plate (6) is located inside the lower mold through hole (4). Multiple upper mold core needles (2) are mounted at the bottom of the mold core (1), and multiple lower mold core needles (5) matching the upper mold core needles (2) are mounted on the top of the lower mold supporting plate (6). Two transverse sliding grooves (10) are symmetrically formed in the inner wall of the lower mold (3). Springs (8) and boss sliding blocks (7) connected to the springs (8) are transversely fixed in the sliding grooves (10). Each boss sliding block (7) comprises a boss (701) and a base (702). Supporting grooves (11) matching the front ends of the bosses (701) are formed in the lower supporting plate (6). The lower supporting plate (6) is supported inside the lower mold through hole (4) by means of the bosses (701). The front ends of the bosses (701) shrink into the sliding grooves (10) and can be fixed in the sliding grooves (10). The extrusion force in extrusion molding is improved The mold filling efficiency and the mold filling capability during extrusion forming are improved, thereby improving the forming quality of a product.

Description

(56) Documents Cited:

WO 2008/073473 A1 CN 202570806 U CN 103273186 A JP 2003205310 A

CN 203900144 U CN 103706653 A CN 102581055 A US 5342189 A (86) International Application Data:

PCT/CN2015/091591 Zh 10.10.2015 (87) International Publication Data:

WO2017/049668 Zh 30.03.2017 (58) Field of Search:

INT CL B21C

Other: See International Search Report for WO2017049668 (71) Applicant(s):

Jiangsu University

301 Xuefu Road Zhenjiang, Jiangsu 212013, China (continued on next page) (54) Title of the Invention: Combined mold core for supercharged multichannel pipe divergent mold Abstract Title: Combined mold core for supercharged multichannel pipe divergent mold (57) A combined mold core for a supercharged multichannel pipe divergent mold, which relates to the field of microbore-size multichannel pipe preparation. The combined mold core comprises a mold core (1), a lower mold (3), and a lower mold supporting plate (6). A lower mold through hole (4) is formed n the center of the lower mold (3). The outer contour of the lower mold supporting plate (6) is same as the shape and the size of the lower mold through hole (4), and the thickness of the lower mold supporting plate (6) is smaller than that of the lower mold (3), and the lower mold supporting plate (6) is located inside the lower mold through hole (4). Multiple upper mold core needles (2) are mounted at the bottom of the mold core (1), and multiple lower mold core needles (5) matching the upper mold core needles (2) are mounted on the top of the lower mold supporting plate (6). Two transverse sliding grooves (10) are symmetrically formed in the inner wall of the lower mold (3). Springs (8) and boss sliding blocks (7) connected to the springs (8) are transversely fixed in the sliding grooves (10). Each boss sliding block (7) comprises a boss (701) and a base (702). Supporting grooves (11) matching the front ends of the bosses (701) are formed in the lower supporting plate (6). The lower supporting plate (6) is supported inside the lower mold through hole (4) by means of the bosses (701). The front ends of the bosses (701) shrink into the sliding grooves (10) and can be fixed in the sliding grooves (10). The extrusion force in extrusion molding is improved The mold filling efficiency and the mold filling capability during extrusion forming are improved, thereby improving the forming quality of a product.

This international application has entered the national phase early

GB 2556820 A continuation (72) Inventor(s):

Yun Wang Xiaming Yang Jinxing Du Kangmei Zhao Zhenying Xu Naifei Ren Haijian Lu Cuntang Wang Xudong Ren Yun Bai (74) Agent and/or Address for Service:

Potter Clarkson LLP

The Belgrave Centre, Talbot Street, NOTTINGHAM, NG1 5GG, United Kingdom

1/4

FIG. 2

2/4

FIG. 4

3/4

FIG. 5

FIG. 6

4/4

FIG. 7

COMBINED MOLD CORE FOR SUPERCHARGED MULTICHANNEL

PIPE DIVERGENT MOLD

TECHNICAL FIELD

The present invention relates to the preparation of microaperture and multichannel pipe, and refers to a combined die core of connected by screw die of pressurized multichannel pipe.

BACKGROUND ART

MicroChannel pipe is a new type of pipe developed in recent years, which is based on the microscale enhanced heat transfer theory. It uses microaperture and a channel with closed structure to realize heat transfer. Compared with heat transfer tubes in conventional scale, heat transfer efficiency can be improved by 100%. Microaperture and multichannel aluminum alloy heat exchange flat pipe has such advantages as light weight, high heat transfer coefficient, compact structure, reliable operation, being safe and environmentally friendly, and it has been developing rapidly in microelectronics, aerospace and other occasions where the size and weight of heat transfer equipment are of great importance.

Each channel of the pipe is formed by the fine core needles parallel arranged, and small diameter core needles are easily deformed in the hot extrusion process, causing the pipe wall thickness to fluctuate and even leading to the fracture of die core. When the extrusion force is too small, it will make extrusion filling not full and cause other problems. When the extrusion force is too high, it is easy to cause the deformation and fracture of small diameter core needles, making the hole not be formed and generating forming defects such as dead holes, fracture and inverted tendons during the extrusion process. As microchannel pipe is a main part of the heat exchanger, its forming quality of is a key factor for the latter.

Patent No.CN102581055A discloses a extrusion die of microchannel heat exchanger flat pipe; but the shortcoming of this technology is that the die core and the core needles are in a whole, if one or more of the core needles is damaged, it will lead to scrap the entire core with a low recycling rate; in addition, the bottom end of the core needle is vacant state. When the extrusion force is too high, it will lead to the deformation or fracture of the core needles. Another patent, No.CN103706653A, discloses a extrusion die of microchannel parallel flow aluminum pipe. However, the shortcoming of this technology is that it only has the bottom die as a separate part without any improvement on the die core and the core needles. As a result, the extrusion force used in the extrusion cannot be improved, and the core needles are still easy to deform or break, making the cavity unable to form and leading to product disqualification problems such as dead holes.

The study to improve microchannel pipes extrusion force, bearing capacity of core needles during extrusion forming and interchangeability of core needles will play a crucial role in improving filling capacity and efficiency of microchannel pipes and there cyclability of die core and, reducing the manufacturing cost of overall die core. SUMMARY OF THE INVENTION

In view of the shortcomings of the existing technologies, such as insufficient extrusion filling, dead holes, fracture and anti-tendons, etc., the present invention provides a combined die core of connected by screw connected by screw die of pressurized multichannel pipe, which avoids problems such as fluctuation of wall thickness of the pipe caused by deformation and fracture of core needles, and dead holes during extrusion forming process of the microaperture and multichannel pipes. It improves extrusion force at work and enhances filling efficiency and filling capacity during extrusion forming process, thus improving the forming quality of the product.

The present invention achieves the above technical objects by the following technical means:

The characteristics of a combined die core of connected by screw connected by screw die of pressurized multichannel pipe include die core, bottom die and bottom die support plate. The die core is located on the top, and the bottom die is located in the bottom; a through-hole is located in the center of the bottom die with the same shape and size as the outer contour of bottom die support plate, which is located inside bottom die through-hole. And the thickness of bottom die support plate is smaller than that of the bottom die and. Several top die core needles are arranged in the bottom of die core, which are transversely fixed with the spring and the boss slider connected with the spring. The boss slider comprises a boss and a base. The bottom die support plate is provided with the supporting groove cooperated with the front end of the boss; the bottom die support plate is supported by the boss inside the bottom die through-hole. And the front end of the boss can shrink to the sliding groove and then is locked in it.

More specifically, the front end of the boss is wedge-shaped and its angle with horizontal plane is Θ; The friction coefficient between the front end of the boss and contact surface of the support groove is μ; the total weight of the bottom die support plate and the connected bottom die core needles is G; the initial compression amount of the spring is Δ and the elasticity coefficient of the spring is k. These quantities should satisfy the following equation: k*A>G*tan0/(2+2p*tanO).

More specifically, bottom die support plate is a rectangular plate; the sliding groove is rectangular; the base is rectangular; the boss is a wedge block; the bottom of the sliding groove has connected square holes; the screwed hole is arranged on the bottom of square hole; the stopper bolt sets in the screw hole; the bottom of the stop spring holds the stopper bolt; the top end holds the base. The horizontal distance between the rear end of the boss and the rear end of the stopper plate is equal to the horizontal size of the support groove.

More specifically, the bottom die support plate is a rectangular plate; the base is rectangular, the sliding groove is the through groove of the front rectangle and the end screwed hole; the bolt set in the screw hole; the bottom of the stop spring holds the stop bolt; the bottom of the sliding groove has connected square holes; the screwed hole is arranged on the bottom of square hole; the stopper bolt sets in the screw hole; the top of the stopper bolt is connected with a stopper spring; the top of the stopper spring holds the ejector block; the top of the slide groove is provided with the slider clamping groove; the horizontal distance of the slider clamping groove is larger than that of the base and the horizontal distance between the front end of the slider clamping groove and the front end of the base is equal to the horizontal size of the support groove; the horizontal distance between the rear end of the ejector block and the front end of the base is larger than that of the support groove.

More specifically, the top die core needles and the die core, the bottom die core needles and the bottom die support plate are detachable connection.

More specifically, the top die core needles and the die core, the bottom die core needles and the bottom die support plate are connected by connected by screw; the end of the top die core needles, contacts the die core and has screw thread, and the other end has a groove; the end of the bottom die core needles, contacts the bottom die support plate, has screw thread, and the other end has the projection. The inner contour of the groove and the outer contour of the projection share the same shape and size; the matched end of the top die core needles and the bottom die core needles have the maximum cross-sectional dimension.

More specifically, the longitudinal section of the front end of the projection is trapezoidal.

More specifically, the front end of the boss has the same shape and size as the support groove.

More specifically, the top die core needles and the bottom die core needles correspond to each other, and are equidistantly arranged on the die core and the bottom die support plate.

More specifically, the cross-section shape of the top die core needles and the bottom die core needles is round, square or irregular.

Beneficial effects of the present invention

The present invention refers to a combined die core of connected by screw connected by screw die of pressurized multichannel pipe. The buffer device is formed by combining various components. At the initial state, the bottom die support plate is supported inside the bottom die through-hole by the boss, and when the extrusion process starts, the front end of the boss is forced to shrink inside the sliding groove and the boss slider can be fixed in the sliding groove so that the bottom die support plate is released; when it needs to be reused, the bottom die support plate is resupported by the boss of the boss slider. In addition, the inserted match of top die core needle and bottom die core needle ensures that bottom die core needle supports top die core needle, which can improve the initial extrusion pressure and ensure that extrusion filling is full and there is no deformation or fracture on top die core needle, improving bearing pressure capacity of working surface of the top die core needles, and finally the quality of extrusion forming parts. The detachable match by the connected by screw of top die core needles and die core and bottom die core needles and bottom die support plate, makes overall die core manufacturing separated, reducing manufacturing cost of overall die core; in addition, the top die core needle can be repaired by removing the damaged part without replacing the entire die core, which can save resources and make maintenance easy. The cross-sectional shapes of the top die core needles and the bottom die core needles can be designed to be round, square or irregular to meet different market needs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.l shows the structural diagram of a combined die core of connected by screw die of pressurized multichannel pipe according to the Embodiment 1 of the present invention.

FIG. 2 shows the structural diagram of a combined die core of connected by screw die of pressurized multichannel pipe according to the Embodiment2 of the present invention.

FIG. 3 shows the cross-sectional view of the die core and the top die core needles.

FIG.4shows the cross-sectional view of the bottom die support plate and the bottom die core needles.

FIG. 5 shows the overhead view of bottom die, bottom die support plate and bottom die core needles.

FIG. 6 shows a connection diagram of the boss slider at the front end of the boss and the bottom die support plate according to the Embodiment 1.

FIG.7 shows a connection diagram of the boss slider at the front end of the boss and the bottom die support plate according to the Embodiment 2.

The reference numbers are as follows:

l-die core, 2-top die core needle, 3-bottom die, 4-bottom die through-hole, 5-bottom die core needle, 6-bottom die support plate, 7-the boss slider, 8-the spring, 9-square hole, 10- the sliding groove, 11- the support groove, 12-the stopper plate, 13-the stopper spring, 14-the stopper bolt, 15-the ejector block, 16-the bolt, 17-the slider clamping groove, 201-the groove, 501-the projection, 701-the boss, 702-the base.

DETAILED METHODS OF THE INVENTION

The present invention is further described in conjunction with drawings and concrete embodiments, but the protection scope of the present invention is not limited to this.

Embodiment 1 :

As shown in FIG. 1 and FIG. 5, a combined die core of connected by screw die of pressurized multichannel pipe includes die corel, bottom die3 and bottom die support plate 6. The die core 1 is located on the top, and the bottom die 3 is located in the bottom, together forming the periphery of the combined die core; the center of the bottom die 3 is provided with the rectangular bottom die through-hole 4; bottom die support plate 6 is located inside the bottom die through-hole 4; the outer contour of bottom die support plate 6 has the same shape and size as the bottom die through-hole 4, making the outer wall of the bottom die support plate 6 close to the inner wall of the bottom die 3; the thickness of bottom die support plate 6 is smaller than that of the bottom die 3, which ensures that the bottom die support plate 6 can be placed in the bottom die through-hole 4 of the bottom die 3.

As shown in FIG. 3, several equidistant top die core needles 2 are mounted on the bottom of the die core 1; the top die core needles 2 and the die core 1 are connected by screw; the end that the top die core needles 2 contacts with the die core 1 in is provided with fine teeth ordinary screw thread, the other end has a groove 201; as shown in FIG. 4 and FIG. 5, the top of the bottom die support plate 6 is mounted with several bottom die core needles 5 corresponding to the top die core needles 2, the bottom die core needles 5 and the bottom die support plate 6 are connected by screw; the end that the bottom die core needles 5 contacts with the die core 1 in is provided with fine teeth ordinary screw thread, the other end has the projection 501. The inner contour of the groove 201 has the same shape and size as the outer contour of the projection 501; the matched end of the top die core needles 2 and the bottom die core needles 5 have the same maximum cross-sectional dimension; the top die core needles 2 are fitted with the bottom die core needles 5 to form the same section size as the whole, which makes overall die core manufacturing become a separated one, reducing manufacturing cost of overall die core; in addition, top die core needles can be repaired by removing the damaged part without replacing the entire die core, which can save resources and maintenance easily; in order to further make the projection 501 more convenient and easy to insert into the groove 201, the front end longitudinal section shape of the projection 501 is designed as the trapezoid.

The bottom die support plate 6 is a rectangular plate; the sliding groove 10 is a rectangular one; the base 702 is a rectangular one; the inner wall of the bottom die 3 is symmetrically provided with two lateral sliding grooves 10; the sliding groove 10 is transversely fixed with the spring 8 and the boss slider 7 connected with the spring 8; the front end of the boss 701 of the boss slider 7 is wedge-shaped; the angle with horizontal plane is 0; the bottom die support plate 6 is provided with the supporting groove 11 cooperated with the front end of the boss 701; the front end of the boss 701 has the same shape and size as the support groove 11; the friction coefficient between the front end of the boss 701 and contact surface of the support groove 11 is μ; the total weight of the bottom die support plate 6 and the connected bottom die core needles 5 is G; the initial compression amount of the spring is Δ; the normal force F generated by the boss 701 through the support groove 11 to the bottom die support plate 6 and the initial elastic force H = k · Δ of the spring 8 should satisfy the relation:

Η = k · Δ = F · sinO, so F = k · Δ / sinO, the upward supporting force of the boss 701 through the support groove 11 to the bottom die support plate 6 is N = k · Δ / tan 0; the friction force between the boss 701 and the supporting groove 11 is f = pF = pk · Δ / sinO; the friction force between the boss 701 and the support groove 11 exerts an upward supporting force Q on the bottom die support plate 6 is Q, Q = f · sin 0 = p k · Δ / sin 0 · sin 0 = p k · Δ; to keep the bottom die support plate 6 and the connected bottom die core needles 5 in an equilibrium state, and 2 · (N + Q) = G holds, that is 2 • (k · Δ / tan 0 + pk · Δ) = G, H = k · Δ = G · tan 0 / (2 + 2p · tan 0), the initial elastic force of the spring 8 is H = G · tan 0 / (2 + 2p · tan 0).

The boss 701 is a wedge block; the bottom of the sliding groove 10 is provided with the connected through square hole 9; the screwed hole is arranged on the bottom of square hole 9; the stopper bolt 14 sets in the screw hole; the bottom of the stop spring 13 holds the stopper bolt 14, the top end holds the base 702; the horizontal distance between the rear end of the boss 701 and the rear end of the stopper plate 12 is equal to the horizontal size of the support groove 11. As shown in FIG. 6, the horizontal distance S between the rear end of the boss 701 and the rear end of the stopper plate 12 is equal to the horizontal size of the support groove 11, which is L*cos0, where L is the hypotenuse of the cross section of the support groove 11.

Before the extrusion, the assembly process is as follows, firstly the top die core needles 2 are screwed into the bottom of the die core 1; the bottom die core needles 5 are screwed into the top of the bottom die support plate 6; bottom die support plate 6 and bottom die core needles 5 are placed in the bottom die through-hole 4, bottom die support plate 6 is supported in the bottom die through-hole 4 by the boss slider 7 and the spring 8. The top die core needles 2 are inserted with bottom die core needles 5 to realize seamless connection. The stopper plate 12 and the stopper spring 13 are placed in stop bolt screw hole; the stopper bolt 14 is screwed into stop bolt screw hole and makes the stopper plate 12 eject the boss slider 7. The compression amount of the spring 8 is Δ; the resulting elasticity is H= k · Δ (k is the elasticity coefficient); the horizontal force acting on the slider 7 is H = k · Δ; the normal force F generated by the boss 701 through the support groove 11 to the bottom die support plate 6 and the initial elastic force H = k · Δ of the spring 8 should satisfy the relation: H = k · Δ = F · sin 0, so F = k · Δ / sin θ, the upward supporting force of the boss 701 through the support groove 11 to the bottom die support plate 6 is N = k · Δ / tan Θ, the friction force between the boss 701 and the supporting groove 11 is f = pF = pk · Δ/ sin Θ; the friction force between the boss 701 and the support groove 11 exerts an upward supporting force Q on the bottom die support plate 6 is Q, Q = f · sin Θ = p k · Δ / sin θ · sin 0 = p k · Δ. To keep the bottom die support plate 6 and the connected bottom die core needles 5 in an equilibrium state, and 2 · (N + Q) = G holds, that is 2 · (k · Δ/ tan Θ + pk · Δ) = G, H = k · Δ = G · tan 0 / (2 + 2p · tan 0), the initial elastic force of the spring 8 is H = G · tan 0 / (2 + 2p · tan Θ).

During the extrusion process, the initial extrusion force is p. When the aluminum alloy material is pressed against the bottom die support plate 6, the extrusion force is gradually increased, and the spring 8 is gradually compressed, due to the length of the sliding groove 11 is L. When sliding distance of the boss slider 7 is L · cos9, the slider 7 will disengage from the support groove 11 and the compression amount of the spring 8 is Δ + L · cosO. Due to the horizontal distance between the rear end of the boss 701 and the rear end of the stopper plate 12 is S = L · cosO, so when sliding distance of the slider 7 is L · cosO, the stopper plate 12 will be ejected under elasticity of the stopper spring 13 and prevent the boss slider 7 from being ejected again. And elasticity of the spring 8 is k · (Δ + L · cosO), the vertical force applied to the bottom die support plate 6 is 2’k*(A+L’cosO)(l/tanO+p), so when the total extrusion force P> 2*k»(A+L»cosO)(l/tanO+p+p-G), the bottom die support plate 6 is ejected and the boss slider 7 is stuck and then the microaperture and multichannel aluminum alloy pipe extruded from the aluminum alloy material is successfully formed.

Embodiment 2:

As shown in FIG. 2, the inner wall of the bottom die 3 is symmetrically provided with two lateral sliding grooves 10; the bottom die support plate 6 is a rectangular plate; the sliding groove 10 is rectangular; the sliding groove 10 is the through groove of the front rectangle and the end screwed hole; the bolt 14 set in the screw hole; the bottom of the stop spring 8 holds the stop bolt 16; the bottom of the sliding groove 10 is provided with the connected through square hole 9, the screwed hole is arranged on the bottom of square hole 9, the stopper bolt 14 sets in the screw hole; the top of the stopper bolt 14 is connected with the stopper spring 13; the top of the stopper spring 13 holds the ejector block 15; the top of the slide groove 10 is provided with the slider clamping groove 17; the horizontal distance of the slider clamping groove 17 is larger than that of the base 702, As shown in FIG. 7, the horizontal distance C between the front end of the slider clamping groove 17 and the front end of the base 702 is equal to the horizontal size of the support groove 11 which is L*cos0; the horizontal distance D between the rear end of the ejector block 15 and the front end of the base 702 is larger than the horizontal distance of the support groove 11 which is L«cos0. The other parts are the same as Embodiment 1.

The working process is as follows: assembling various components before extrusion; during the extrusion process, the initial extrusion force is p, and when the aluminum alloy material is pressed against the bottom die support plate 6, the extrusion force is gradually increased, and the spring 8 is gradually compressed, due to the length of the sliding groove 11 is L; when sliding distance of the boss slider 7 is L · cos0, the slider 7 will disengage from the support groove 11, due to the horizontal distance C between the front end of the slider clamping groove 17 and the front end of the base 702 is equal to the horizontal size of the support groove 11 which is L*cos0; the horizontal distance D between the rear end of the ejector block 15 and the front end of the base 702 is larger than the horizontal distance of the support groove 11 which is L»cos0, so when the sliding distance of the slider 7 is L · cosO, the ejector block 15 pushes the sliding block 7 into the sliding groove 17, and prevents the boss slider 7 from being ejected under the elasticity ofthe spring 8, enabling the bottom die support plate 6 to be ejected smoothly, and ensuring the continued extrusion and quality of extrusion parts; meanwhile the bottom die support plate 6 is ejected, and then the micro aperture and multichannel aluminum alloy pipe extruded from the aluminum alloy material is successfully formed.

The embodiments are preferred ones of the present invention, but the invention is not limited to the those described above, and any obvious modifications, replacements or substitutions that can be made by those skilled in the art without departing from the substance of the invention are within the protection scope of the present invention.

Claims

1. The characteristics of a combined die core of connected by screw die of pressurized multichannel pipe include die core (1), bottom die (3) and bottom die support plate (6); the die core (1) is located on the top, and the lower die (3) is located in the bottom; the bottom die through-hole (4) is located in the center of the bottom die (3); the outer contour of bottom die support plate (6) has the same shape and size as the bottom die through-hole (4), the thickness of bottom die support plate (6) is smaller than the thickness of the bottom die (3); several top die core needles (2) are arranged in the bottom of die core (1), several bottom die core needles (5), which cooperate with top die core needles (2), are arranged in the top of bottom die support plate (6); the inner wall of the bottom die (3) is symmetrically provided with two lateral sliding grooves (10); the sliding groove (10) is transversely fixed with the spring (8) and the boss slider (7) matched with the sliding groove (10), the boss slider (7) comprises the boss (701) and the base (702); the bottom die support plate (6) is provided with the supporting groove (11) cooperated with the front end of the boss (701), the bottom die support plate (6) is supported inside the bottom die through-hole (4) by the boss (701); The front end of the boss (701) can shrink to the sliding groove (10) and be locked there.

2. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 1, the front end of the boss (701) is wedge-shaped, the angle with horizontal plane is Θ; the friction coefficient between the front end of the boss (701) and contact surface of the support groove (11) is μ, the total weight of the bottom die support plate (6) and the connected bottom die core needles (5) is G; the initial compression amount of the spring is Δ and the elasticity coefficient of the spring (8) is k, these quantities should satisfy the following equation: k’A>G*tanO/(2+2p*tanO).

3. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 2, bottom die support plate (6) is a rectangular plate; the sliding groove (10) is a rectangular one; base (702) is a rectangular one; the boss (701) is a wedge block; the bottom of the sliding groove (10) is provided with the connected through square hole (9); the screwed hole is arranged on the bottom of square hole (9); the stopper bolt (14) sets in the screw hole; the bottom of the stop spring (13) holds the stopper bolt (14), the top end holds the base (702); the horizontal distance between the rear end of the boss (701) and the rear end of the stopper plate (12) is equal to the horizontal size of the support groove (11).

4. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 2, the bottom die support plate (6) is a rectangular plate; the base (702) is a rectangular base, the sliding groove (10) is the through groove of the front rectangle and the end screwed hole; the bolt (14) set in the screw hole; the bottom of the stop spring (8) holds the stop bolt (16); the bottom of the sliding groove (10) is provided with the connected through square hole (9), the screwed hole is arranged on the bottom of square hole (9), the stopper bolt (14) sets in the screw hole, the top of the stopper bolt (14) is connected with the stopper spring (13), the top of the stopper spring (13) holds the ejector block (15); the top of the slide groove (10) is provided with the slider clamping groove (17); the horizontal distance of the slider clamping groove(17) is larger than that of the base (702), the horizontal distance between the front end of the slider clamping groove (17) and the front end of the base (702) is equal to the horizontal size of the support groove (11); the horizontal distance between the rear end of the ejector block (15) and the front end of the base (702) is larger than that of the support groove (11).

5. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 3 or 4, the top die core needles (2) and the die core (1), the bottom die core needles (5) and the bottom die support plate (6) are detachable connection.

6. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 5, the top die core needles (2) and the die core (1), the bottom die core needles (5) and the bottom die support plate (6) are connected by screw; the end that the top die core needles (2) contacts with the die core (1) in is provided with screw thread, the other end has a groove (201); the end that the bottom die core needles (5) contacts with the die core (1) in is provided with screw thread, the other end has the projection (501), the inner contour of the groove (201) has the same shape and size as the outer contour of the projection (501); the matched end of the top die core needles (2) and the bottom die core needles (5) have the maximum cross-sectional dimension.

7. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 6, the longitudinal section of the front end of the projection (501) is trapezoidal.

8. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 7, the front end of the boss (701) has the same shape and size as the support groove (11).

9. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 2, the top die core needles (2) and the bottom die core needles (5) correspond to each other, and are equidistantly arranged on the die core (1) and the bottom die support plate (6).

10. A combined die core of connected by screw die of pressurized multichannel pipe as set forth in claim 2, the cross-section shape of the top die core needles (2) and the bottom die core needles (5) is round, square or irregular.