Weldless vapor chamber flexible forming method and device

Abstract

The invention provides a weldless vapor chamber flexible forming method and device. The forming device comprises a pressing upper die, a pressing lower die, a flange plate, a pressure supply connector, an upper side pressing die, a lower side pressing die, a guide pipe, a guide pipe support, a corrugation forming die piece, a corrugation die limiting block and a die holder. The forming method comprises the steps that a round pipe blank is made into a flat pipe with the runway-shaped section through hydraulic pressing, then the flat pipe is made into a corrugated pipe through hydraulic bulging, and the weldless vapor chamber shell is obtained. And finally, the vapor chamber is assembled, the liquid absorption core is installed in the vapor chamber shell and fixed, the vapor chamber is sealed, the liquid injection pipe is welded, the liquid injection and vacuumizing processes are completed, and then the liquid injection pipe is sealed. The ultrathin flexible vapor chamber formed through the method has high quality and size precision, only the two ends of the vapor chamber need to be welded and sealed in the sealing procedure when the vapor chamber is manufactured, the welding area of the vapor chamber is reduced, the quality of the manufactured vapor chamber can be improved, and the service life of the manufactured vapor chamber can be prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat pipes, and more specifically, relates to a method and device for flexibly forming a seamless heat pipe. Background Art

[0002] With the rise of foldable and wearable electronic devices and the miniaturization development of electronic devices, ultra-thin flexible heat pipes have gradually become a research hotspot in the heat dissipation field. Ultra-thin flexible heat pipes have good flexibility and thermal conductivity, and play an important role in solving the heat dissipation problem of small-volume flexible electronic devices. A common structure of a flexible heat pipe is a three-section structure, which consists of a rigid section, a flexible section, and a rigid section. Usually, a metal bellows or a polymer tube is used as the flexible section of the heat pipe to achieve the flexible bending function.

[0003] However, the sections of the three-section flexible heat pipe are usually connected by welding, and the welding quality directly affects the airtightness and overall quality of the heat pipe, thereby affecting the heat transfer performance and service life of the heat pipe. Moreover, the cross-section of the tube shell of the three-section flexible heat pipe is usually circular, and the circular cross-section is not conducive to the installation of the heat pipe in the narrow space of small electronic devices. The large gap between the circular cross-section heat pipe and the heat source will bring a large contact thermal resistance, affecting the heat transfer performance of the heat pipe. Therefore, it is necessary to study a method and device for flexibly forming a seamless heat pipe to form an ultra-thin flexible heat pipe with a more flat cross-section and good folding performance. Summary of the Invention

[0004] The present invention provides a method and device for flexibly forming a seamless heat pipe for forming an ultra-thin flexible heat pipe. The flexible forming method of hydroforming is used to integrally form the outer shell of the heat pipe. First, a round tube blank is pressed into a flat tube, and then the flat tube is hydroformed to obtain the flat corrugated outer shell of the heat pipe. The formed part has high dimensional accuracy and good bending performance. And when manufacturing the heat pipe, only the two ends of the heat pipe need to be welded and sealed during the sealing process, reducing the welding area of the heat pipe, and improving the quality and service life of the manufactured heat pipe.

[0005] The specific technical solution of the present invention is as follows: A method and device for flexibly forming a seamless heat pipe, the forming device includes: a pressing upper die (1), a pressing lower die (2), a flange (3), a pressure supply joint (4), an upper side pressing die (5), a lower side pressing die (6), a guiding tube (7), a guiding tube bracket (8), a corrugation forming die piece (9), a corrugation die limiting block (10), and a die base (11).

[0006] The profiling lower die (2) is of a rectangular cubic block structure, with a semi-runway cross-section long groove (201) opened on the upper surface. The two ends of the semi-runway cross-section long groove are transitioned into semi-circular cross-section long grooves (202) by a semi-runway cross-section structure, and finally a conical semi-circular groove (203) is transitioned outwards with an increasing diameter from the semi-circular cross-section. The upper surface is provided with a profiling die taper pin hole (204) and a profiling die socket head cap screw counterbore (205).

[0007] The profiling upper die (1) is of a rectangular cubic block structure, similar to the profiling lower die (2). A semi-runway cross-section long groove is opened on the lower surface. The two ends of the semi-runway cross-section long groove are transitioned into semi-circular cross-sections by a semi-runway cross-section structure, and finally a conical semi-circular groove is transitioned outwards with an increasing diameter from the semi-circular cross-section. The lower surface is provided with a pin hole.

[0008] The flange (3) is of a cylindrical structure, with a flange central threaded hole (301) opened at the axis for connecting with the threaded end (402) of the pressure supply joint. The flange edge threaded holes (302) are symmetrically distributed around the periphery for connecting with an external pressure supply device.

[0009] One end of the pressure supply joint (4) is machined with a conical micro frustum (401), and the other end is machined as the threaded end (402) of the pressure supply joint. An infusion hole (403) is opened on the side surface of the pressure supply joint, and a micropore (404) is opened along the axial center of the conical micro frustum. External hydraulic oil can be introduced into the initial circular tube blank through the infusion hole and the micropore.

[0010] The upper side pressing die (5) and the lower side pressing die (6) have the same structure, both of which are rectangular block structures. A side pressing through groove (501) is machined at the center position of the joint surface of each pair of side pressing dies. The side pressing through groove is transitioned from a semi-runway cross-section long groove to a semi-circular cross-section groove, and then transitioned to a conical semi-circular groove. Side pressing die threaded holes (502) are machined on both the upper side pressing die and the lower side pressing die, and they can be connected to each other by screws.

[0011] The guide tube (7) is a cylindrical thin tube, and the outer diameter dimension is the same as the outer diameter dimension of the semi-guide through hole (903) on the corrugation forming die piece (9). A through hole is machined at the axis of the guide tube cylinder.

[0012] The support surface (801) of the guide tube support (8) is of a concave shape. A rectangular through hole (802) and a guide tube through hole (803) are machined on the support surface. The rectangular through hole can support the passage of the upper side pressing die (5) and the lower side pressing die (6). The size of the guide tube through hole is the same as that of the guide tube (7) and is used for installing and supporting the guide tube. A support threaded hole (804) is opened on the support seat (805) and is connected to the die base (11) by screws.

[0013] The corrugation forming die plate (9) is a rectangular thin sheet part, with a micro-rectangular ring groove (901) machined in the center for forming the corrugation wave crest. The micro-rectangular ring groove has a racetrack-shaped structure, which is compatible with the formed racetrack-shaped corrugation structure. The groove depth is equal to the width dimension of the corrugation wave crest cross-section on the final part. At the same time, a rounded corner ring groove (902) is machined, and the outer diameter dimension of the rounded corner is equal to the corrugation trough dimension on the final part. A semi-guiding through hole (903) is machined on the corrugation forming die plate.

[0014] The corrugation die limiting block (10) is machined with a plurality of equally spaced rectangular limiting grooves (1001). The groove width is the same as the width of the corrugation forming die plate. The groove spacing is determined by the width of the blank in the forming area during the forming process. The number of equally spaced rectangular grooves is the same as the number of corrugation forming die plates (9).

[0015] The bottom outer edge of the die base (11) is provided with die base threaded holes (1101) for fixation, and the upper surface is provided with upper die base threaded holes (1102), which are respectively connected to the lower pressing die (2) and the guiding tube support (8) by screws in different forming steps.

[0016] Further, the semi-racetrack-shaped cross-section long groove (201), semi-circular cross-section groove (202) and conical semi-circular groove (203) in the upper pressing die (1) and the lower pressing die (2) are connected to form a pressing block through groove (206).

[0017] Further, the conical semi-circular groove (203) of the upper pressing die (1) and the lower pressing die (2) and the conical micro frustum (401) of the pressure supply joint are on the same axis line. The conical semi-circular grooves of the upper pressing die and the lower pressing die and the conical micro frustum of the pressure supply joint are jointly fitted for installation and sealing; the lower pressing die and the upper pressing die are positioned by pins and the conical pin holes (204) of the pressing die; the countersunk head holes (205) of the hexagon socket head cap screws of the pressing die in the lower pressing die are connected to the die base threaded holes (1101) by screws.

[0018] Further, the conical semi-circular grooves (503) of the upper side pressing die and the lower side pressing die and the conical micro frustum (401) of the pressure supply joint are on the same axis line. The conical semi-circular grooves of the upper side pressing die and the lower side pressing die and the conical micro frustum of the pressure supply joint are jointly fitted for installation and sealing.

[0019] Further, the corrugation forming die plate (9) is a symmetric split part. One corrugation forming die plate is composed of a pair of corrugation half dies (904) connected. Its parting surface passes through the midpoint of the rectangular side of the racetrack-shaped structure, dividing the micro-rectangular ring groove and the rounded corner ring groove into two symmetric parts. Ultra-small pin holes (905) are machined perpendicular to the surface on the two joint surfaces. A pair of corrugation half dies are positioned and connected by pins with ultra-small diameters in cooperation with the pin holes; the number of corrugation forming die plates is determined according to the number of corrugations of the formed part.

[0020] The present invention provides a method for flexibly forming a seamless heat pipe, including the following steps:

[0021] Step 1: A circular tube blank is formed into a flat tube with a runway-shaped cross-section by hydraulic pressing. Fix the die base to the forming area using screws, fix the lower pressing die to the upper surface of the die base using screws, place the initial circular tube blank in the through groove of the pressing block, connect two flange plates to the pressure supply joint, connect the external hydraulic equipment to the flange plates, align and install the conical micro frustum of the pressure supply joint with the conical semi-circular groove of the lower pressing die, and position the upper pressing die and the lower pressing die using a pin. The external hydraulic equipment acts on the upper pressing die, and the upper pressing die and the lower pressing die start to close the mold. After the mold closing is completed, the external hydraulic equipment starts to fill and expand the liquid through the pressure supply joint, and the initial circular tube blank is formed into a flat tube with a runway-shaped cross-section. After pressure relief, remove the upper pressing die, the left and right pressure supply joints translate and retract, remove the flat tube, and remove the lower pressing die.

[0022] Step 2: The flat tube is formed into a corrugated tube by hydraulic expansion. Fix the guide tube bracket to the die base using screws, place the corrugated die limit block on the upper surface of the die base, place both ends of the flat tube on two lower side pressing dies, install the upper side pressing die on the lower side pressing die using screws, place the installed lower side pressing die at the rectangular through hole of the guide tube bracket, sequentially install the corrugated forming die pieces on the flat tube using pins, the corrugated forming die pieces are located in the rectangular groove of the corrugated die limit block, install the guide tube through the semi-guide through hole of the corrugated forming die piece on the guide tube through hole of the guide tube bracket, and the left and right pressure supply joints translate and advance until the conical micro frustum of the pressure supply joint is aligned and installed with the conical semi-circular grooves of the upper and lower side pressing dies. The external hydraulic equipment starts to fill and pre-expand the liquid through the pressure supply joint, and the flat tube undergoes a certain degree of plastic deformation and bulges. After the pre-expansion is completed, remove the corrugated die limit block, and the other die components remain unchanged. The external hydraulic equipment pushes the left and right pressure supply joints and the upper and lower side pressing dies to close the mold and expand. After the forming is completed and the pressure is relieved, the left and right pressure supply joints translate and retract, and the dies are removed in the reverse order of the installation sequence. The obtained corrugated tube is the heat pipe shell.

[0023] Step 3: Assemble the heat pipe. Provide a liquid absorption core, install the liquid absorption core into the heat pipe shell and fix it, seal the heat pipe and weld a liquid injection pipe at one end, complete the liquid injection and vacuum pumping processes through the liquid injection pipe, and then seal the liquid injection pipe.

[0024] Further, the heat pipe shell is made of a metal material. The initial circular tube blank used for forming can be obtained by the following method: Weld multiple strips into a plate, bend the plate and weld it into a circular tube, and then draw the circular tube to obtain the initial circular tube blank with the specified dimensions.

[0025] Further, the liquid absorption core adopts a flexible structure such as a porous wire mesh or a woven belt, and its material is made of hydrophilic materials such as copper or stainless steel. The liquid absorption core is fixed on the heat pipe shell by means of welding, sintering, etc.

[0026] Further, the seamless weld means that the heat pipe shell is integrally formed, and there is no need to use welding to connect between the rigid section and the flexible section. Only welding and other processes are required in the subsequent sealing process of the heat pipe.

[0027] Further, the liquid chamber pressure during the forming process is determined by process tests or finite element simulations.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1) In the forming die device of the present invention, to form parts with different cross-sectional dimensions, only the upper pressing die, the lower pressing die, and the upper and lower side pressing dies need to be replaced. To form parts with different numbers and shapes of corrugations, only the corrugation forming die piece and the corrugation die limit block need to be replaced. The corresponding die can be flexibly replaced according to the part shape, and the die utilization rate is high, which can effectively reduce the production and manufacturing cost of the die device;

[0030] 2) The forming die device of the present invention has relatively few components, a simple structure, and is convenient to assemble, which can effectively improve the production efficiency of parts;

[0031] 3) In the forming method of the present invention, the round tube blank is formed into a flat tube by hydraulic pressing, and then the flat tube is subjected to fluid-filled bulging to obtain a flat corrugated tube, which can form tiny complex corrugated parts with relatively high corrugation height, large deformation amount, large number, and small spacing. Compared with the method of directly flattening a corrugated tube with a circular cross-section to produce a flat corrugated tube, the formed parts have higher quality and dimensional accuracy;

[0032] 4) The forming method of the present invention integrally forms the shell of the heat pipe, and the produced heat pipe only needs to weld and seal the two ends of the heat pipe shell, reducing the welding area of the heat pipe, which can improve the quality and service life of the produced heat pipe. Description of the Drawings

[0033] Figure 1 It is a schematic diagram of a part of an ultra-thin flexible heat pipe shell.

[0034] Figure 2 It is a schematic assembly structure diagram of the forming die device.

[0035] Figure 3 It is a schematic structure diagram of the lower pressing die.

[0036] Figure 4 It is a schematic diagram of the die closing process of the upper pressing die and the lower pressing die.

[0037] Figure 5 It is a schematic structural diagram of a flange.

[0038] Figure 6 It is a schematic structural diagram and a sectional view of a pressure supply joint.

[0039] Figure 7 It is a schematic structural diagram of an upper side press mold.

[0040] Figure 8 It is a schematic structural diagram of a guide tube support.

[0041] Figure 9 It is a side view of a corrugated half mold.

[0042] Figure 10 It is a schematic structural diagram and an installation schematic diagram of a corrugated forming die piece.

[0043] Figure 11 It is a schematic structural diagram of a corrugated die limit block.

[0044] Figure 12 It is a schematic structural diagram of a die base.

[0045] The label descriptions in the figure are as follows:

[0046] 1 - upper pressing die; 2 - lower pressing die; 201 - semi - runway - shaped long groove; 202 - long groove with semi - circular cross - section; 203 - conical semi - circular groove; 204 - conical pin hole of pressing die; 205 - counterbore for socket - head cap screw of pressing die; 206 - through - slot of pressing block; 3 - flange; 301 - central threaded hole of flange; 302 - edge threaded hole of flange; 4 - pressure supply joint; 401 - conical micro - frustum; 402 - threaded end of pressure supply joint; 403 - infusion hole; 404 - micro - hole; 5 - upper side press mold; 501 - side - pressing through - slot; 502 - threaded hole of side - pressing mold; 503 - conical semi - circular groove of side - pressing mold; 6 - lower side press mold; 7 - guide tube; 8 - guide tube support; 801 - supporting surface; 802 - rectangular through - hole; 803 - through - hole for guide tube; 804 - threaded hole of support; 805 - support seat; 9 - corrugated forming die piece; 901 - micro - rectangular ring groove; 902 - rounded - corner ring groove; 903 - semi - guiding through - hole; 904 - corrugated half mold; 905 - ultra - small pin hole; 10 - corrugated die limit block; 1001 - rectangular limit groove; 11 - die base; 1101 - threaded hole of die base; 1102 - upper threaded hole of die base. Specific embodiments

[0047] In order to more clearly understand the above - mentioned objects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0048] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0049] This embodiment provides a method and device for flexible forming of a seamless heat pipe, as Figures 1 to 12 shown. The forming device includes: a pressing upper die 1, a pressing lower die 2, a flange 3, a pressure supply joint 4, an upper side pressing die 5, a lower side pressing die 6, a guiding tube 7, a guiding tube bracket 8, a corrugation forming die sheet 9, a corrugation die limiting block 10, and a die base 11.

[0050] Figure 1 Shown is a schematic diagram of a thin - wall flexible heat pipe shell part, whose material is SUS304 stainless steel. The cross - sections at both ends of the part are flat racetrack - shaped, and the middle section has multiple corrugations with equal height and equal spacing. The thickness of the pipe is only 0.05 mm. Since the corrugation height is relatively high compared to the inner diameter of the flat tube, the amount of deformation is large, and the number of formed corrugations is large, the spacing between adjacent corrugations is small (1 mm), the fillet size in the corrugation is small (0.2 mm), the wall thickness is extremely thin (0.05 mm), and the size of the rectangular side (7 mm) in the cross - section size is larger than the diameter of the semi - circular side (3 mm), presenting a racetrack - shaped cross - section. For such a micro - complex part, conventional hydroforming methods such as tube hydroforming are difficult to achieve forming. Design the approximate shape and dimensional parameters of the corresponding hydroforming die according to the specific dimensional parameters of the part.

[0051] Figure 2 Shown is the assembly structure schematic diagram of the forming die device. During the forming process, first, the die is assembled into the Figure 2 structure shown in the right figure for the first - step hydraulic pressing to press the initial round tube blank into a flat tube. Subsequently, the die is assembled into the Figure 2 structure shown in the left figure for the second - step fluid - filled bulging to make the flat tube into a corrugated tube by fluid - filled bulging.

[0052] Figure 3 Shown is the structure schematic diagram of the pressing lower die. The pressing lower die 2 is a rectangular cubic block structure, with a semi - racetrack - shaped long groove 201 opened on the upper surface. The two ends of the semi - racetrack - shaped cross - section long groove are transitioned from the semi - racetrack - shaped cross - section structure into a semi - circular cross - section long groove 202, and finally, a tapered semi - circular groove 203 is formed by increasing the diameter outward from the semi - circular cross - section; a pressing die conical pin hole 204 and a pressing die socket - head cap screw counterbore 205 are opened on the upper surface;

[0053] Specifically, the pressing upper die 1 is a rectangular cubic block structure, similar to the structure of the pressing lower die 2. A semi - racetrack - shaped cross - section long groove is opened on the lower surface. The two ends of the semi - racetrack - shaped cross - section long groove are transitioned from the semi - racetrack - shaped cross - section structure into a semi - circular cross - section, and finally, a tapered semi - circular groove is formed by increasing the diameter outward from the semi - circular cross - section; a pin hole is opened on the lower surface;

[0054] Specifically, as Figure 2 , Figure 3 shown, the semi - runway - shaped cross - section long grooves 201, semi - circular cross - section grooves 202 and conical semi - circular grooves 203 in the upper pressing die 1 and the lower pressing die 2 are connected to form the pressing block through - groove 206.

[0055] Specifically, as Figure 2 shown, the conical semi - circular grooves 203 of the upper pressing die 1 and the lower pressing die 2 and the conical micro - frustum 401 for the supply joint are on the same axis line. The conical semi - circular grooves of the upper and lower pressing dies and the conical micro - frustum of the supply joint are jointly fitted for installation and sealing; the lower pressing die and the upper pressing die are positioned through pins and the conical pin holes 204 of the pressing die; the countersunk head holes 205 of the socket - head cap screws of the pressing die of the lower pressing die are connected to the threaded holes 1101 of the die holder through screws.

[0056] Figure 5 The structure diagram of the flange is shown. As Figure 2 , Figure 5 shown, the flange 3 is a cylindrical structure. A central threaded hole 301 is opened at the axis to connect with the threaded end 402 of the supply joint, and flange edge threaded holes 302 are symmetrically distributed around the periphery to connect with external supply equipment.

[0057] Figure 6 The structure diagram and cross - sectional view of the supply joint are shown. One end of the supply joint 4 is processed with a conical micro - frustum 401, and the other end is processed as the threaded end 402 of the supply joint. An infusion hole 403 is opened on the side of the supply joint, and a micro - hole 404 is opened along the axial center of the conical micro - frustum. External hydraulic oil can be introduced into the initial circular tube blank through the infusion hole and the micro - hole.

[0058] Figure 7 The structure diagram of the upper side - pressing die is shown. The upper side - pressing die 5 and the lower side - pressing die 6 have the same structure, both being rectangular block structures. A side - pressing through - groove 501 is processed at the center position of the joint surface of each pair of side - pressing dies. The side - pressing through - groove transitions from a semi - runway - shaped cross - section long groove to a semi - circular cross - section groove, and then to a conical semi - circular groove. Side - pressing die threaded holes 502 are processed on both the upper side - pressing die and the lower side - pressing die, and they can be connected to each other through screws.

[0059] Specifically, as Figure 2 shown, the conical semi - circular grooves 503 of the upper side - pressing die and the lower side - pressing die and the conical micro - frustum 401 of the supply joint are on the same axis line. The conical semi - circular grooves of the upper and lower side - pressing dies and the conical micro - frustum of the supply joint are jointly fitted for installation and sealing.

[0060] Specifically, as Figure 2As shown, the guiding tube 7 is a cylindrical thin tube, with an outer diameter dimension identical to that of the semi-guiding through-hole 903 on the corrugation forming die piece 9. A through-hole is machined on the axis of the guiding tube cylinder;

[0061] Figure 8 The following shows the structural schematic diagram of the guiding tube support. As Figure 2 、 Figure 8 shown, the support surface 801 of the guiding tube support 8 is concave-shaped. A rectangular through-hole 802 and a guiding tube through-hole 803 are machined on the support surface. The rectangular through-hole can support the upper die 5 and the lower die 6 to pass through. The dimension of the guiding tube through-hole is the same as that of the guiding tube 7, which is used to install and support the guiding tube. A support screw hole 804 is opened on the support base 805 and is connected to the die base 11 by screws;

[0062] Figure 9 The following shows the side view of the corrugated half die, Figure 10 The following shows the structural schematic diagram and installation schematic diagram of the corrugation forming die piece. The corrugation forming die piece 9 is a rectangular thin sheet part. A micro-rectangular ring groove 901 is machined in the center for the formation of the corrugation wave crest. The micro-rectangular ring groove is in a racetrack-shaped structure, which is compatible with the formed racetrack-shaped corrugation structure. The groove depth is equal to the width dimension of the corrugation wave crest cross-section on the final part. At the same time, a rounded corner ring groove 902 is machined, and the outer diameter dimension of the rounded corner is equal to the dimension of the corrugation trough on the final part. A semi-guiding through-hole 903 is machined on the corrugation forming die piece;

[0063] Specifically, as Figure 9 、 Figure 10 shown, the corrugation forming die piece 9 is a symmetrically split part. A corrugation forming die piece is composed of a pair of corrugated half dies 904 connected. Its parting surface passes through the midpoint of the rectangular side of the racetrack-shaped structure, dividing the micro-rectangular ring groove and the rounded corner ring groove into two symmetric parts. Ultra-small pin holes 905 are machined perpendicular to the surface on the two joint surfaces. A pair of corrugated half dies are positioned and connected by pins with an ultra-small diameter; The number of corrugation forming die pieces is determined by the number of corrugations of the formed part;

[0064] Figure 11 The following shows the structural schematic diagram of the corrugated die limit block. The corrugated die limit block 10 is machined with a plurality of equally spaced rectangular limit grooves 1001. The groove width is the same as the width of the corrugation forming die piece. The groove spacing is determined by the width of the blank in the forming area during the forming process. The number of equally spaced rectangular grooves is the same as the number of corrugation forming die pieces 9, which is 32;

[0065] Figure 12 The following shows the structural schematic diagram of the die base. As Figure 2 、 Figure 12 shown, screw holes 1101 are opened on the outer edge of the bottom of the die base 11 for fixation. Screw holes 1102 are opened on the upper surface and are respectively connected to the lower die 2 and the guiding tube support 8 by screws in different forming steps.

[0066] The present invention provides a method for flexibly forming a seamless heat pipe, which can form an ultra-thin flexible heat pipe. The structure of the heat pipe housing is as shown in Figure 1 the following figure. Its specific embodiments include three operation steps: circular tube hydroforming, flat tube fluid-filled bulging, and heat pipe assembly:

[0067] Circular tube hydroforming step: As shown in the following figure, use screws to fix the die base 11 to the forming area, use screws to fix the hydroforming lower die 2 to the upper surface of the die base 11, place the initial circular tube blank in the through groove 206 of the pressing block, connect the two flange plates 3 with the pressure supply joint 4, connect the external hydraulic equipment with the flange plate 3, align and install the conical micro frustum 401 of the pressure supply joint with the conical semi-circular groove 203 of the hydroforming lower die, and use pins to position the hydroforming upper die 1 and the hydroforming lower die 2. The assembled structure is as shown in Figure 2 the following figure. The external hydraulic equipment acts on the hydroforming upper die, and the hydroforming upper die and the hydroforming lower die start to close. The closing process is as shown in Figure 2 the following figure. After the closing is completed, the external hydraulic equipment starts to fill the liquid and expand the shape through the pressure supply joint 4, and forms the initial circular tube blank into a flat tube with a runway-shaped cross-section. After the pressure is relieved, remove the hydroforming upper die 1, the left and right pressure supply joints 4 translate and retract, remove the flat tube, and remove the hydroforming lower die 2. Figure 4

[0068] Flat tube fluid-filled bulging step: As shown in the left figure, use screws to fix the guide tube bracket 8 to the die base, place the corrugated die limit block 10 on the upper surface of the die base 11, place the two ends of the flat tube on the two lower side pressing dies 6, use screws to install the upper side pressing die 5 on the lower side pressing die 6, place the installed lower side pressing die at the rectangular through hole 802 of the guide tube bracket, successively use pins to install the corrugated forming die piece 9 on the flat tube, the corrugated forming die piece 9 is located at the rectangular limit groove 1001 of the corrugated die limit block, pass the guide tube 7 through the semi-guide through hole 903 of the corrugated forming die piece and install it on the guide tube through hole 803 of the guide tube bracket, and the left and right pressure supply joints 4 translate and advance until the conical micro frustum 401 of the pressure supply joint is aligned and installed with the side pressing die conical semi-circular groove 603 of the upper and lower side pressing dies. The assembled structure is as shown in Figure 2 Figure 2 the left figure. The external hydraulic equipment starts to fill the liquid through the pressure supply joint 4 for pre-bulging, and the maximum pressure is set to 25 MPa. The flat tube undergoes a certain degree of plastic deformation and bulges. After the pre-bulging is completed, remove the corrugated die limit block 10, and the other die components remain unchanged. The closing pressure is set to 25 MPa, and the external hydraulic equipment pushes the left and right pressure supply joints and the upper and lower side pressing dies to close and bulge. After the forming is completed and the pressure is relieved, the left and right pressure supply joints translate and retract, and the dies are removed in reverse order of the installation sequence. The obtained corrugated tube is the heat pipe housing.

[0069]

[0069] Heat pipe assembly steps: In this embodiment, a copper mesh is used as the wick. The wick is loaded into and spot-welded to the heat pipe housing, and then sintered to fix the wick to the heat pipe housing. The heat pipe is sealed and a copper tube is welded at one end as the liquid injection tube. The liquid injection and vacuum pumping processes are completed through the liquid injection tube. In this embodiment, pure water is used as the working medium, and then the liquid injection tube is welded and sealed.

[0070] For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several variations and improvements can be made to the embodiments of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A seamless heat pipe flexible forming device, characterized in that: The forming device includes: a top forming die, a bottom forming die, a flange, a pressure supply joint, an upper side pressing die, a lower side pressing die, a guide tube, a guide tube support, a corrugation forming die plate, a corrugation die limit block, and a die base; The top forming die is of a rectangular cubic block structure, with a long groove having a semi-runway-shaped cross-section on its lower surface. The two ends of the semi-runway-shaped cross-section long groove are transitioned from a semi-runway-shaped cross-section structure into a semi-circular cross-section, and finally, a tapered semi-circular groove is transitioned outwards with an increasing diameter from the semi-circular cross-section; pin holes are opened on the lower surface; The bottom forming die is of a rectangular cubic block structure, with a long groove having a semi-runway-shaped cross-section on its upper surface. The two ends of the semi-runway-shaped cross-section long groove are transitioned from a semi-runway-shaped cross-section structure into a semi-circular cross-section, and finally, a tapered semi-circular groove is transitioned outwards with an increasing diameter from the semi-circular cross-section; a tapered pin hole and a countersunk head hole for an internal hexagonal screw are opened on the upper surface; The flange is of a cylindrical structure, with a threaded hole opened at the axis for connection with the pressure supply joint, and threaded holes are symmetrically distributed around the periphery for connection with an external pressure supply device; One end of the pressure supply joint is processed with a tapered micro-circular table, and the other end is processed as a threaded end. An infusion hole is opened on the side surface of the pressure supply joint, and a micro-hole is opened along the axial center of the micro-circular table. External hydraulic oil is introduced into the initial circular tube blank through the infusion hole and the micro-hole; Both the upper side pressing die and the lower side pressing die are of a rectangular block structure. At the center position of the joint surface of each pair of side pressing dies, a side pressing through groove is processed. The side pressing through groove is transitioned from a semi-runway-shaped cross-section long groove to a semi-circular cross-section groove, and then transitioned to a tapered semi-circular groove; threaded holes are processed on both the upper side pressing die and the lower side pressing die, and they are connected to each other by screws; The guide tube is a cylindrical thin tube, and the outer diameter dimension is the same as the outer diameter dimension of the semi-guide through hole on the corrugation forming die plate. A through hole is processed at the cylindrical axis; The support surface of the guide tube support is of a concave shape. A rectangular through hole and a guide tube through hole are processed on the support surface. The rectangular through hole supports the passage of the upper side pressing die and the lower side pressing die. The size of the guide tube through hole is the same as that of the guide tube, which is used to install and support the guide tube; threaded holes are opened on the support base and are connected to the die base by screws; The corrugation forming die plate is a rectangular thin sheet part. A micro-rectangular ring groove is processed at the center for forming the corrugation wave crest. The rectangular ring groove is of a runway-shaped structure, which is consistent with the formed runway-shaped corrugation structure. The groove depth is equal to the cross-section width dimension of the corrugation wave crest on the final part. At the same time, a rounded corner ring groove is processed, and the outer diameter dimension of the rounded corner is equal to the dimension of the corrugation wave valley on the final part. A semi-guide through hole is processed on the die plate; The corrugation die limit block is processed with a plurality of equally spaced rectangular grooves. The groove width is the same as the width of the forming die plate. The groove spacing is determined by the width of the blank in the forming area during the forming process. The number of equally spaced rectangular grooves is the same as the number of corrugation forming die plates; Threaded holes are opened on the outer edge of the bottom of the die base for fixation, and threaded holes are opened on the upper surface, which are respectively connected to the bottom forming die and the guide tube support by screws in different forming steps.

2. The flexible forming device of a seamless heat pipe according to claim 1, characterized in that: The semi-runway-shaped cross-section long groove, the semi-circular cross-section groove, and the tapered semi-circular groove in the top forming die and the bottom forming die are connected to form a press block through groove.

3. The flexible forming device for a seamless heat pipe according to claim 1 or 2, characterized in that: The conical semi-circular grooves of the upper and lower profiling dies and the tiny round platform of the pressure supply joint are located on the same axis. The conical semi-circular grooves of the upper and lower profiling dies and the tiny round platform of the pressure supply joint are jointly fitted for installation and sealing. The lower profiling die and the upper profiling die are positioned by pins. The lower profiling die is connected to the die base by screws.

4. A seamless heat pipe flexible forming device according to claim 3, characterized in that: The conical semi-circular grooves of the upper side pressing die and the lower side pressing die and the tiny round platform of the pressure supply joint are located on the same axis. The conical semi-circular grooves of the upper side pressing die and the lower side pressing die and the tiny round platform of the pressure supply joint are jointly fitted for installation and sealing.

5. A seamless heat pipe flexible forming device according to claim 1, characterized in that: The corrugation forming die piece is a symmetrically split part. One corrugation forming die piece is composed of a pair of corrugation half dies connected. Its parting surface passes through the midpoint of the rectangular side of the runway-shaped structure, dividing the micro-rectangular ring groove and the rounded ring groove into two symmetrical parts. Ultra-small pin holes are machined perpendicular to the surface on the two joint surfaces. A pair of corrugation half dies are positioned and connected through ultra-small diameter pins fitting into the pin holes. The number of corrugation forming die pieces is determined according to the number of corrugations of the formed part.

6. A forming method for the seamless heat pipe flexible forming device described in claim 1, characterized in that: It includes the following steps: Step 1: The round tube blank is made into a flat tube with a runway-shaped cross-section by hydraulic profiling. Use screws to fix the die base to the forming area, use screws to fix the lower profiling die to the upper surface of the die base. Place the initial round tube blank in the through groove of the pressing block. Connect the two flange plates to the pressure supply joint, connect the external hydraulic equipment to the flange plates. Align and install the tiny round platform of the pressure supply joint with the conical semi-circular groove of the lower profiling die. Use pins to position the upper profiling die and the lower profiling die. The external hydraulic equipment acts on the upper profiling die, and the upper profiling die and the lower profiling die start to close the die. After the die closing is completed, the external hydraulic equipment starts to fill and expand the liquid through the pressure supply joint, forming the initial round tube blank into a flat tube with a runway-shaped cross-section. After pressure relief, remove the upper profiling die, the left and right pressure supply joints translate and retract, remove the flat tube, and remove the lower profiling die. Step 2: The flat tube is made into a corrugated tube by hydraulic expansion. Use screws to fix the guide tube bracket to the die base, place the corrugation die limiting block on the upper surface of the die base. Place both ends of the flat tube on the two lower side pressing dies. Use screws to install the upper side pressing die on the lower side pressing die. Place the installed lower side pressing die at the rectangular through hole of the guide tube bracket. Sequentially use pins to install the corrugation forming die pieces on the flat tube. The corrugation forming die pieces are located in the rectangular grooves of the corrugation die limiting block. Pass the guide tube through the semi-guide through holes of the corrugation forming die pieces and install it on the guide tube through holes of the guide tube bracket. The left and right pressure supply joints translate and advance until the tiny round platforms of the pressure supply joints are aligned and installed with the conical semi-circular grooves of the upper and lower side pressing dies. The external hydraulic equipment starts to fill and pre-expand the liquid through the pressure supply joint, and the flat tube undergoes a certain degree of plastic deformation and bulges. After the pre-expansion is completed, remove the corrugation die limiting block, and the other die components remain unchanged. The external hydraulic equipment pushes the left and right pressure supply joints and the upper and lower side pressing dies to close and expand the die. After the forming is completed and the pressure is relieved, the left and right pressure supply joints translate and retract, and the dies are removed in the reverse order of the installation sequence. The obtained corrugated tube is the heat sink housing. Step 3: Assemble the heat pipe; Provide a wick, install the wick into the heat pipe housing and fix it, seal the heat pipe and weld a liquid injection pipe at one end, complete the liquid injection and vacuum pumping processes through the liquid injection pipe, and then seal the liquid injection pipe.

7. A method for flexible forming of a seamless heat pipe, according to claim 6, characterized in that: The heat pipe housing is made of metal material. The initial round tube blank used for forming is obtained by welding multiple strips into a plate, bending the plate and welding it into a round tube, and then drawing the round tube to obtain the initial round tube blank with the specified size.

8. A method for flexible forming of a seamless heat pipe, according to claim 6, characterized in that: The wick adopts a flexible structure of porous wire mesh or woven tape, and the material is made of copper or stainless steel. The wick is fixed on the heat pipe housing by welding or sintering.

9. A method for flexible forming of a seamless heat pipe, according to claim 6, characterized in that: The "seamless weld" means that the heat pipe housing is integrally formed, and there is no need to connect the rigid section and the flexible section by welding. Only the welding process is required when the heat pipe is sealed subsequently.

10. A method for flexible forming of a seamless heat pipe, according to claim 6 or 7 or 8 or 9, characterized in that: The liquid chamber pressure during the forming process is determined by process experiments or finite element simulations.

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