Forming method of precious metal thin-wall bobbin

Abstract

The invention discloses a forming method of a precious metal thin-wall bobbin, which comprises the following steps of: drawing for multiple times, placing a precious metal sheet on a press machine provided with drawing dies, processing the metal sheet into a bobbin fitting by using the drawing dies with different specifications, and increasing the length of the bobbin fitting and reducing the diameter and the thickness of the bobbin fitting in each time of drawing; and rotary swaging is conducted for multiple times, a core rod is inserted into the bobbin fitting subjected to drawing machining, rotary swaging machining is conducted on the bobbin fitting where the core rod is inserted in rotary swaging machines of different specifications, the length of the bobbin fitting is increased, and the diameter and the thickness of the bobbin fitting are reduced through each rotary swaging machining till the needed precious metal thin-wall bobbin is obtained. The method has the beneficial effects that the thin-wall bobbin is machined by adopting the metal sheet through multiple times of deep drawing and multiple times of rotary swaging, no weld joint or weld beading exists on the thin-wall bobbin, the overall process is simpler, the weld joint does not need to be polished, and due to the fact that no weld joint exists, the overall strength of the bobbin is higher, cracks are not prone to being generated in the using process, and the quality is better.

Description

Technical Field

[0001] The invention relates to a forming method of a precious metal thin-walled bobbin, and belongs to the technical field of manufacturing precious metal thin-walled bobbin. Background Art

[0002] The manufacture of bobbins usually involves rolling metal plates on a plate rolling machine to form a cylindrical shape, and then welding the metal plates. The bobbins made by this method are prone to cracks under certain circumstances due to the presence of welds, and welding processes will inevitably result in weld nodules, which not only affect the quality of the inner circle of the bobbin, but also usually require grinding of the welds. The overall strength of the bobbin is also not ideal, and the arc uniformity of the surface of the bobbin made by rolling is also difficult to ensure. Summary of the invention

[0003] The purpose of the present invention is to provide a method for forming a precious metal thin-wall bobbin, so as to solve the technical defects of the bobbin made by rolling and welding in the prior art, that is, the overall strength of the bobbin is low and cracks are easily generated.

[0004] To solve the above problems, the technical solution adopted by the present invention is: a forming method of a precious metal thin-walled bobbin, including multiple deep drawing, placing a precious metal sheet on a press equipped with a drawing die, and processing the metal sheet into a bobbin part by drawing dies of different specifications, each time the deep drawing increases the length of the bobbin part and reduces the diameter; multiple rotary forging, inserting a mandrel into the bobbin part after the deep drawing process, and rotary forging the bobbin part with the inserted mandrel in rotary forging machines of different specifications, each time the rotary forging process increases the length of the bobbin part and reduces the diameter and thickness, until the desired precious metal thin-walled bobbin is obtained.

[0005] As a further improvement of the present invention, the metal sheet is annealed before the first deep drawing process, and from the second deep drawing process onwards, the tube member is annealed before each deep drawing process, and the tube member is annealed before each rotary forging process.

[0006] As a further improvement of the present invention, the drawing die includes an upper die seat, a hollow platform assembly, a first die and a plurality of second die seats, the upper die seat is fixed on a slide of a press and is driven up and down by the press, the hollow platform assembly is fixed on a workbench of the press, the first die and the second die both include an upper die unit and a lower die unit; the upper die unit includes a punch and a punch fixing plate, the punch fixing plate is used to fix the punch on the lower surface of the upper die seat, the diameter of the punch of the first die is greater than the diameter of the punch of the second die, the length of the punch of the first die is less than the length of the punch of the second die, and the diameters of the punches of the plurality of second die seats decrease successively and the lengths increase successively; the lower die unit includes a concave die, the concave die is fixed on the hollow The platform assembly has a circular hole running through the upper and lower parts of the die, and the diameter of the circular hole on the die of the first die is larger than the diameter of the circular hole on the die of the second die, and the diameters of the circular holes on the die of the multiple second dies decrease successively, and the circular holes on the die correspond to the convex dies of the upper die unit respectively; the precious metal sheet is first placed on the die of the first die, and the slide of the press moves downward to push the convex die of the first die to move downward, so as to press the precious metal sheet into the circular hole to form a bobbin part, and the bobbin part falls down from the hollow platform assembly for collection, and the bobbin part pressed by the first die is then placed on the circular hole of the die of the second die in turn, and is pressed downward by the convex die of the second die to form a bobbin part with a smaller diameter and a larger length, and falls down from the hollow platform assembly for collection.

[0007] As a further improvement of the present invention, the first mold also includes a blank holding ring and at least two nitrogen springs. The punch of the first mold passes through the blank holding ring and the blank holding ring can move vertically relative to the punch of the first mold. The cylinder body of the nitrogen spring is fixed on the upper mold base. The piston rod of the nitrogen spring vertically extends and retracts downward and connects to the blank holding ring. When in use, the blank holding ring presses the edge of the metal sheet to prevent the punch of the first mold from pressing the precious metal sheet downward, causing large bumps on the precious metal sheet.

[0008] As a further improvement of the present invention, the first mold and the second mold both also include a unloading mechanism, which is arranged at the lower part of the die, and includes a slide rail seat plate, a pulley seat plate is provided with a circular through hole running through it from top to bottom, and the slide rail seat plate is provided with more than two slide grooves communicating with the circular through holes along the circumferential direction of the circular through holes, a spring and a unloading block are arranged in the slide groove, and the unloading block is located on the side close to the circular through hole, one end of the spring is connected to the unloading block, and the other end is connected to the end of the slide groove away from the circular through hole, when the bobbin part enters the circular through hole from the circular hole, the unloading block is squeezed and the spring is contracted, and when the bobbin part moves to below the unloading block, the unloading block resists against the punch, and when the punch moves upward, the unloading block blocks the top end of the bobbin part to prevent the bobbin part from moving upward with the punch.

[0009] As a further improvement of the present invention, the first mold and the second mold both further include a die backing plate, the die backing plate is mounted on the hollow platform assembly, and the unloading mechanism is mounted on the die backing plate.

[0010] As a further improvement of the present invention, the first mold and the second mold both further include a positioning ring, which is arranged on the concave mold and is used to position the precious metal sheet or the bobbin piece.

[0011] As a further improvement of the present invention, it further comprises at least two limit blocks, the bottom of the limit blocks is fixed on the hollow platform assembly, and when the upper die seat moves downward to abut against the limit blocks, the upper die seat stops moving downward.

[0012] As a further improvement of the present invention, the rotary forging machine includes a casing, a main shaft, multiple forging heads and a plurality of rollers. The casing is provided with circular mounting holes running through both ends thereof. The rollers are evenly arranged in the mounting holes along the circumferential direction and are evenly spaced. The main shaft is circular and has a central through hole thereon. The outer diameter of the main shaft is smaller than the diameter of the mounting hole. The main shaft is arranged in the mounting hole and is driven by a driving device to rotate in the mounting hole. Multiple slideways are evenly arranged in the circumferential direction on the main shaft. A forging head is arranged in each slideway. The forging head can move in the slideway. An arc groove is arranged on one end of the forging head located at the central through hole. The end of the forging head away from the central through hole extends out of the slideway and is arranged in an arc shape. When the main shaft rotates, the forging head moves in a direction away from the central through hole under the action of centrifugal force. When the forging head presses against the rollers, the rollers push the forging head to move in the direction of the central through hole. The arc grooves at the ends of multiple forging heads can be assembled into a complete circular hole.

[0013] As a further improvement of the present invention, the forging head is composed of two sections, which are connected by an adjusting pad in the middle, and the adjusting pad can be replaced to change the length of the forging head.

[0014] In summary, the beneficial effects of the present invention are as follows: the present invention uses a metal sheet to be processed into a thin-walled bobbin by multiple deep drawing and multiple rotary forging, and there is no weld and no weld nodule on the bobbin. The overall process is simpler and there is no need to grind the weld. In addition, since there is no weld, the overall strength of the bobbin is higher, it is not easy to crack during use, and the quality is better.

[0015] The invention improves the mechanical properties and mechanical properties of the bobbin part by annealing the metal sheet and the bobbin part.

[0016] The present invention first uses a first die to draw a metal sheet into a tubular member, and then uses multiple second dies to perform multiple drawing processes on the tubular member, so that the diameter of the tubular member gradually decreases and the length gradually increases. The first die and multiple second dies in the present invention are installed on the same upper die base and hollow platform assembly, so the present invention can use a press to drive the first die and all the second die to move, thereby reducing the cost of the present invention.

[0017] The present invention is provided with a nitrogen spring and a blank holder ring. When the punch presses the metal sheet downward, the blank holder ring presses the edge of the metal sheet, and the metal sheet does not produce large bumps and depressions, thereby improving the quality of the bobbin fitting.

[0018] The present invention is provided with a discharge mechanism, and when the punch moves upward, the discharge mechanism blocks the bobbin parts, which can effectively prevent the bobbin parts from moving upward synchronously with the punch moving upward.

[0019] The die pad in the present invention facilitates the installation of the unloading mechanism on the hollow platform assembly. The present invention provides a positioning ring to facilitate the positioning of the metal sheet or the tube. The present invention provides a limit block to limit the up and down movement of the upper die seat.

[0020] The forging head in the present invention moves in a direction away from the bobbin part by the rotating centrifugal force, and the forging head abuts against the roller, and the roller pushes the forging head to move toward the bobbin part. The reciprocating movement of the forging head forges the bobbin part to reduce the diameter of the bobbin part.

[0021] The invention can change the length of the forging head by replacing the adjusting pads with different thicknesses, thereby improving the versatility of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the drawing die in the present invention.

[0023] Figure 2 It is a structural schematic diagram of the unloading mechanism in the present invention.

[0024] Figure 3 It is a structural schematic diagram of the rotary forging machine in the present invention.

[0025] Figure 4 It is a schematic diagram of rotary forging a tube member according to the present invention.

[0026] Figure 5 It is a schematic diagram of the deep drawing of the metal sheet into a cylindrical member in the present invention.

[0027] Among them: 1. upper die seat; 2. hollow platform assembly; 3. first die; 4. second die; 5. upper die unit; 6. lower die unit; 7. punch; 8. punch fixing plate; 9. die; 10. tube fitting; 11. pressure ring; 12. nitrogen spring; 13. unloading mechanism; 14. slide rail seat plate; 15. circular through hole; 16. slide groove; 17. spring; 18. unloading block; 19. die pad; 20. positioning ring; 21. limit block; 22. housing; 23. main shaft; 24. forging head; 25. roller; 26. mounting hole; 27. arc groove; 28. adjustment pad; 29. ​​punch pad; 30. first slide groove unit; 31. second slide groove unit; 32. third slide groove unit; 33. chuck; 34. core rod. DETAILED DESCRIPTION

[0028] The invention relates to a forming method of a precious metal thin-walled tube, which comprises multiple drawing processes and multiple rotary forging processes.

[0029] The multiple deep drawing specifically includes: placing the precious metal sheet on a press machine equipped with a deep drawing die, and processing the metal sheet into a tube member 10 by using deep drawing dies of different specifications, and each deep drawing increases the length of the tube member 10 and reduces the diameter. In the present invention, the precious metal sheet is annealed before the first deep drawing process, and the tube member 10 is annealed before each deep drawing process starting from the second deep drawing process. Figure 5 shown.

[0030] The multiple rotary forgings are specifically as follows: a core rod 34 is inserted into the bobbin part 10 after deep drawing, and the bobbin part 10 with the inserted core rod 34 is clamped by a chuck 33 in a rotary forging machine and rotary forged using dies of different specifications. Each rotary forging process increases the length of the bobbin part 10 and reduces its diameter and thickness until the desired precious metal thin-walled bobbin is obtained. In the present invention, the bobbin part 10 is annealed before each rotary forging process.

[0031] like Figure 1 As shown, the drawing die used in the present invention includes an upper die base 1, a hollow platform assembly 2, a first die 3 and a plurality of second dies 4, the upper die base 1 is fixed on a slide of a press and is driven by the press to move up and down, the hollow platform assembly 2 is fixed on a workbench of the press, the first die 3 and the second die 4 both include an upper die unit 5 and a lower die unit 6, the upper die unit 5 of the first die 3 is fixed on the left end of the upper die base 1, the upper die unit 5 of the second die 4 is installed on the upper die base 1 at equal intervals from left to right, and the upper die unit 5 of the second die 4 is located on the right side of the upper die unit 5 of the first die 3, and the lower die units 6 of the first die 3 and the second die 4 are respectively located below the upper die unit 5.

[0032] like Figure 1As shown, the upper die unit 5 in the present invention includes a punch 7 and a punch fixing plate 8. The punch fixing plate 8 is used to fix the punch 7 on the lower surface of the upper die seat 1. The punch 7 in the present invention is a cylindrical structure, and its bottom edge is set as a spherical surface to effectively increase the drawing fillet and reduce the risk of deep drawing cracking of the barrel bottom. The top of the punch 7 is provided with a punch pad 29 larger than its diameter. The punch pad 29 is formed integrally with the punch 7. The punch 7 in the present invention passes downward through the punch fixing plate 8. The punch fixing plate 8 is a circular plate, whose diameter is equal to the diameter of the punch pad 29. The punch 7 is fixed to the upper die base 1 by multiple bolts that pass through the punch fixing plate 8 and the punch pad 29 and are threadedly matched with the upper die base 1. In the present invention, the diameter of the punch 7 of the first die 3 is larger than the diameter of the punch 7 of all the second dies 4, the length of the punch 7 of the first die 3 is smaller than the length of the punch 7 of all the second dies 4, and the diameters of the punches 7 of the multiple second dies 4 from left to right decrease and the lengths increase successively.

[0033] like Figure 1 As shown, the lower mold unit 6 in the present invention includes a die 9, which is cylindrical as a whole and fixed on the hollow platform assembly 2. A circular hole is opened on the die 9 along its center line direction and passes through it from top to bottom, and the diameter of the circular hole on the die 9 of the first mold 3 is larger than the diameter of the circular hole on the die 9 of all the second molds 4. The diameters of the circular holes on the die 9 of the multiple second molds 4 decrease successively from left to right. The circular holes on the die 9 correspond to the punches 7 of the upper mold unit 5 respectively, and the diameter of the circular hole of each groove 9 is smaller than the diameter of the punch 7 located above it.

[0034] When the present invention is in use, the precious metal sheet is first placed on the die 9 of the first mold 3, and the press slide moves downward to push the punch 7 of the first mold 3 to move downward, pressing the precious metal sheet into the circular hole to form a tube member 10, which falls downward from the hollow platform assembly 2 for collection, and the tube members 10 pressed by the first mold 3 are then placed on the circular holes of the die 9 of the second mold 4 in turn, and are pressed downward by the punch 7 of the second mold 4 to form tube members 10 with smaller diameter and larger length, which fall downward from the hollow platform assembly 2 for collection.

[0035] like Figure 1As shown, the first mold 3 in the present invention also includes a blank holder ring 11 and at least two nitrogen springs 12. The punch 7 of the first mold 3 passes through the blank holder ring 11 and the blank holder ring 11 can move vertically relative to the punch 7 of the first mold 3. The lower surface of the blank holder ring 11 in the present invention protrudes downward to form an annular protrusion. The cylinder body of the nitrogen spring 12 passes through the punch fixing plate 8 and the punch pad 29 and is fixed on the upper mold base 1. The piston rod of the nitrogen spring 12 vertically retracts downward and connects to the blank holder ring 11. The connection between the piston rod of the nitrogen spring 12 and the blank holder ring 11 is located on the outside of the annular protrusion. In use, the blank holder ring 11 presses the edge of the metal sheet to prevent the punch 7 of the first mold 3 from pressing the precious metal sheet downward, so that the precious metal sheet produces larger bumps and depressions, thereby improving the manufacturing quality of the precious metal thin-walled bobbin.

[0036] like Figure 1 and Figure 2As shown, the first mold 3 and the second mold 4 in the present invention are also provided with a discharge mechanism 13, which is arranged at the lower part of the concave mold 9, and includes a slide rail seat plate 14, the slide rail seat plate 14 is a circular plate, and a circular through hole 15 running through the upper and lower parts of the slide rail seat plate 14 is opened along the center line direction of the slide rail seat plate 14, and four slide grooves 16 communicating with the circular through hole 15 are evenly opened on the slide rail seat plate 14 along the circumferential direction of the circular through hole 15, and a spring 17 and a discharge block 18 are arranged in the slide groove 16, and the discharge block 18 is located on the side close to the circular through hole 15, and one end of the spring 17 is connected to the discharge block 18. The first end of the discharging block 18 is connected with the material block 18, and the other end is connected with the end of the slide groove 16 away from the circular through hole 15. The spring 17 can extend or contract with the movement of the discharging block 18. When the bobbin fitting 10 enters the circular through hole 15 from the circular hole, the discharging block 18 is squeezed and the spring 17 is contracted. When the bobbin fitting 10 moves below the discharging block 18, the discharging block 18 is pushed by the spring 17 to press against the punch 7. When the punch 7 moves upward, the discharging block 18 presses against the top of the bobbin fitting 10 to prevent the bobbin fitting 10 from moving upward with the punch 7. When the punch 17 moves upward and separates from the bobbin fitting 10, the bobbin fitting 10 falls downward under the action of gravity. The chute 16 of the present invention includes a first chute unit 30, a second chute unit 31 and a third chute unit 32. The first chute unit 30 and the third chute unit 32 are respectively located on both sides of the second chute unit 31 and communicate with the second chute unit 31. One end of the first chute unit 30 away from the second chute unit 31 is communicated with the circular through hole 15. The widths of the first chute unit 30 and the third chute unit 32 are equal and are smaller than the width of the second chute unit 31. The discharge block 18 is a convex structure, and its wider end is located at the first chute unit 31. The spring 17 is located in the third chute unit 32 and is connected to the wider end of the unloading block 18. The shape of the unloading block 18 and the shape of the chute 16 can guide and limit the movement of the unloading block 18. In the present invention, the top of the unloading block 18 is set to an inclined surface so that the bottom of the bobbin can smoothly pass through the circular through hole 15 downward.

[0037] like Figure 1As shown, the first mold 3 and the second mold 4 in the present invention are also provided with a die pad 19, the die pad 19 is installed on the hollow platform assembly 2, the unloading mechanism 13 is installed on the die pad 19, and the unloading mechanism 13 is installed on the hollow platform assembly 2 through the die pad 19; the first mold 3 and the second mold 4 in the present invention are also provided with a positioning ring 20, the positioning ring 20 is arranged on the die 9, and is used to position the precious metal sheet or the bobbin 10; the present invention is provided with at least two limit blocks 21, and the number of the limit blocks 21 in the present invention is preferably set to two, and they are respectively fixed at the left and right ends of the hollow platform assembly 2, and the bottom of the limit block 21 is fixed on the hollow platform assembly 2, and when the upper mold base 1 moves downward to abut against the limit block 21, the upper mold base 1 stops moving downward.

[0038] like Figure 3 As shown, the rotary forging machine used in the present invention includes a housing 22, a main shaft 23, a plurality of forging heads 24 and a plurality of rollers 25. The housing 22 is provided with circular mounting holes 26 penetrating both ends thereof. The rollers 25 are evenly arranged in the mounting holes 26 along the circumferential direction and are evenly spaced. The main shaft 23 is circular and has a central through hole thereon. The outer diameter of the main shaft 23 is smaller than the diameter of the mounting hole 26. The main shaft 23 is arranged in the mounting hole. One end of the main shaft 23 extends out of the housing 22 and is driven by a driving device to rotate in the mounting hole 26. There is a gap between the main shaft 23 and the rollers 25, that is, the main shaft 23 and the rollers 25 are not in contact. Four slideways are evenly arranged in the circumferential direction on the main shaft 23. The slideways are opened along the radial direction of the main shaft 23. A forging head 24 is arranged in each slideway. 24 can move in the slideway. The forging head 24 is located at one end of the central through hole and has 45-degree chamfers on both sides. An arc groove 27 is provided on the end face of the forging head 24. The end of the forging head 24 away from the central through hole extends out of the slideway and is arranged in an arc shape. When the main shaft 23 rotates, the forging head 24 moves in the direction away from the central through hole under the action of centrifugal force. When the forging head 24 abuts against the roller 25, the roller 25 pushes the forging head 24 to move in the direction of the central through hole. When the forging head 24 moves to the chamfered inclined surface at its end, the arc grooves 27 at the ends of multiple forging heads 24 can be assembled into a complete circular hole. The forging head 24 in the present invention is the aforementioned rotary forging machine mold. The difference in molds refers to the different diameters of the circles corresponding to the arc grooves 27 at the ends of the forging heads 24. The barrel fitting 10 passing therethrough is rotary forged. The forging head 24 in the present invention is composed of two sections, which are connected by an adjustment pad 28 in the middle. Replacing the adjustment pad 28 is used to change the length of the forging head 24. Figure 4As shown, the arc groove 27 of the forging head 24 in the present invention includes a feeding area, a working area and a discharging area, wherein the working area has the smallest diameter and is used to forge the tube fitting 10. The feeding area and the discharging area are both conical in shape, and the diameter of the connection between the feeding area and the discharging area and the working area is equal to the diameter of the working area, and the diameter of the end away from the working area is larger than the diameter of the working area. The feeding area has a small slope and a large length, which is beneficial to reducing the resistance and vibration of the billet feeding. The feeding area and the working area have a smooth transition, so that the wall thickness of the billet forms a slow change process to avoid cracks. The discharging area is short in length and has a large slope to avoid annular forging marks after discharging.

[0039] like Figure 4 As shown, when the present invention is in use, a core rod 34 is inserted into the bobbin member 10, and the collet 33 is used to clamp the bobbin member 10 and extend it into the central through hole on the main shaft 23. The main shaft 23 rotates, and when the forging head 24 abuts against the roller 25, the roller 25 pushes the forging head 24 to forge the bobbin member 10, so that the diameter of the bobbin member 10 is reduced and the length is increased at the same time. The collet 33 pushes the bobbin member 10 to move, thereby realizing the feeding of the bobbin member 10 during the rotary forging process.

[0040] The present invention has strong mobility and is also suitable for mass production in response to the current situation of small amount of precious metal materials, single piece or small batch, and many processing specifications and sizes. The bobbin formed by the present invention can be made into a temperature measuring sleeve commonly used in the glass fiber industry, which can be further spun into analysis crucibles of various shapes, and can also be processed into leak plates or crucible leak nozzles by cold drawing and cutting. Compared with the prior art, the present invention is unique in processing relatively short thin-walled bobbins, has higher processing efficiency, and excellent molding quality, and overcomes the defects of uneven wall thickness and easy cracking due to high-temperature creep of leak nozzles, reinforcing rib tubes, temperature measuring tubes and other products made of platinum alloy welded tubes.

[0041] The parts not specifically described in the above description are all prior art, or can be implemented by prior art. Moreover, the specific implementation cases described in the present invention are only preferred implementation cases of the present invention, and are not used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent scope of the present invention should be regarded as the technical scope of the present invention.

Claims

1. A method for forming a precious metal thin-walled tube, characterized in that: include Multiple deep drawing, placing the precious metal sheet on a press equipped with a deep drawing die, and processing the metal sheet into a tube member (10) using deep drawing dies of different specifications, each time the deep drawing increases the length of the tube member (10) and reduces its diameter; The tube member (10) is subjected to multiple rotary forgings, a mandrel is inserted into the drawn tube member (10), and the tube member (10) with the mandrel inserted is subjected to rotary forging in a rotary forging machine using dies of different specifications, wherein each rotary forging process increases the length of the tube member (10) and reduces the diameter and thickness thereof, until the desired precious metal thin-walled tube member is obtained.

2. The method for forming a precious metal thin-walled bobbin according to claim 1, characterized in that: Before the first deep drawing process, the metal sheet is annealed. Starting from the second deep drawing process, the tube member (10) is annealed before each deep drawing process. Before each rotary forging process, the tube member (10) is annealed.

3. The method for forming a precious metal thin-walled bobbin according to claim 1 or 2, characterized in that: The drawing die comprises an upper die seat (1), a hollow platform assembly (2), a first die (3) and a plurality of second dies (4); the upper die seat (1) is fixed on a slide block of a press and is driven by the press to move up and down; the hollow platform assembly (2) is fixed on a workbench of the press; and both the first die (3) and the second die (4) comprise an upper die unit (5) and a lower die unit (6); The upper die unit (5) comprises a punch (7) and a punch fixing plate (8), the punch fixing plate (8) being used to fix the punch (7) on the lower surface of the upper die seat (1), the diameter of the punch (7) of the first die (3) being greater than the diameter of the punch (7) of the second die (4), the length of the punch (7) of the first die (3) being less than the length of the punch (7) of the second die (4), and the diameters of the punches (7) of the plurality of second dies (4) are successively reduced and the lengths are successively increased; The lower die unit (6) comprises a die (9), the die (9) being fixed to the hollow platform assembly (2), the die (9) being provided with a circular hole penetrating the upper and lower parts thereof, and the diameter of the circular hole on the die (9) of the first die (3) being larger than the diameter of the circular hole on the die (9) of the second die (4), the diameters of the circular holes on the die (9) of the plurality of second die (4) decreasing in sequence, and the circular holes on the die (9) respectively corresponding to the convex dies (7) of the upper die unit (5); The precious metal sheet is first placed on the concave die (9) of the first die (3), and the slide of the press machine moves downward to push the convex die (7) of the first die (3) to move downward, so that the precious metal sheet is pressed into the circular hole to form a tube member (10), which then falls downward from the hollow platform assembly (2) for collection. The tube members (10) pressed by the first die (3) are then placed on the circular hole of the concave die (9) of the second die (4), and are pressed downward by the convex die (7) of the second die (4) to form tube members (10) with a smaller diameter and a larger length, which then fall downward from the hollow platform assembly (2) for collection.

4. The method for forming a precious metal thin-walled bobbin according to claim 3, characterized in that: The first mold (3) further comprises a blank holder (11) and at least two nitrogen springs (12); the punch (7) of the first mold (3) passes through the blank holder (11) and the blank holder (11) can move vertically relative to the punch (7) of the first mold (3); the cylinder of the nitrogen spring (12) is fixed on the upper mold base (1); the piston rod of the nitrogen spring (12) vertically retracts downward and connects to the blank holder (11); in a state of use, the blank holder (11) presses the edge of the metal sheet to prevent the punch (7) of the first mold (3) from pressing the precious metal sheet downward, thereby causing the precious metal sheet to have relatively large unevenness.

5. The method for forming a precious metal thin-walled bobbin according to claim 3, characterized in that: The first mold (3) and the second mold (4) both further include a discharge mechanism (13), which is arranged at the lower part of the concave mold (9), and includes a slide rail seat plate (14), a circular through hole (15) penetrating the slide rail seat plate (14) from top to bottom, and two or more slide grooves (16) in communication with the circular through hole (15) are arranged on the slide rail seat plate (14) along the circumferential direction of the circular through hole (15), and a spring (17) and a discharge block (18) are arranged in the slide groove (16), and the discharge block (18) is located near the circular through hole (15). ) side, one end of the spring (17) is connected to the discharge block (18), and the other end is connected to the end of the slide groove (16) away from the circular through hole (15). When the tube member (10) enters the circular through hole (15) from the circular hole, the discharge block (18) is squeezed and the spring (17) is contracted. When the tube member (10) moves below the discharge block (18), the discharge block (18) abuts against the punch (7). When the punch (7) moves upward, the discharge block (18) blocks the top end of the tube member (10) to prevent the tube member (10) from moving upward with the punch (7).

6. The method for forming a precious metal thin-walled bobbin according to claim 5, characterized in that: The first mold (3) and the second mold (4) both further include a die backing plate (19), the die backing plate (19) being mounted on the hollow platform assembly (2), and the unloading mechanism (13) being mounted on the die backing plate (19).

7. The method for forming a precious metal thin-walled bobbin according to claim 3, characterized in that: The first mold (3) and the second mold (4) both further include a positioning ring (20), which is arranged on the concave mold (9) and is used to position the precious metal sheet or the bobbin piece (10).

8. The method for forming a precious metal thin-walled bobbin according to claim 3, characterized in that: It also comprises at least two limit blocks (21), the bottoms of the limit blocks (21) being fixed on the hollow platform assembly (2), and when the upper die base (1) moves downwards to abut against the limit blocks (21), the upper die base (1) stops moving downwards.

9. The method for forming a precious metal thin-wall bobbin according to claim 1 or 2, characterized in that: The rotary forging machine comprises a housing (22), a main machine shaft (23), a plurality of forging heads (24) and a plurality of rollers (25). The housing (22) is provided with circular mounting holes (26) penetrating both ends thereof. The rollers (25) are evenly arranged in the mounting holes (26) along the circumferential direction and are evenly spaced. The main machine shaft (23) is circular and has a central through hole. The outer diameter of the main machine shaft (23) is smaller than the diameter of the mounting hole (26). The main machine shaft (23) is arranged in the mounting hole and is driven by a driving device to rotate in the mounting hole (26). The main machine shaft (23) is evenly provided with a plurality of sliding holes along the circumferential direction. A forging head (24) is arranged in each slideway, and the forging head (24) can move in the slideway. An arc groove (27) is arranged on one end of the forging head (24) located at the central through hole. The end of the forging head (24) away from the central through hole extends out of the slideway and is arranged in an arc shape. When the main machine shaft (23) rotates, the forging head (24) moves in a direction away from the central through hole under the action of centrifugal force. When the forging head (24) abuts against the roller (25), the roller (25) pushes the forging head (24) to move in the direction of the central through hole. The arc grooves (27) at the ends of multiple forging heads (24) can be assembled into a complete circular hole.

10. The method for forming a precious metal thin-wall bobbin according to claim 9, characterized in that: The forging head (24) is composed of two sections, which are connected by an adjustment pad (28) in the middle. The adjustment pad (28) is replaced to change the length of the forging head (24).

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