A forming die and method for stretch forming a fine tube

Abstract

The application discloses a forming die and method for drawing forming a thin pipe, and relates to the technical field of drawing forming a thin pipe, which comprises an upper die and a lower die. The upper die comprises an upper support, an upper pad plate and a fixing plate which are sequentially and fixedly arranged on the bottom surface of the upper support, and a limiting plate and a discharging plate which are sequentially and fixedly arranged below the fixing plate. A second vertical spring is fixedly arranged in the upper support, the bottom end of the second vertical spring is fixedly provided with a second force transmission column, and a drawing punch which penetrates through the discharging plate downwards is fixedly arranged on the bottom surface of the fixing rod. The lower die comprises a base, a lower pad plate and a concave die plate which are sequentially and fixedly arranged from bottom to top. A small hole is arranged in the concave die insert below the drawing punch, and a first vertical spring and a third vertical spring which are respectively arranged on the two sides of the concave die insert are fixedly arranged in the base. The application has the advantages of greatly reducing the working strength of workers, greatly improving the forming efficiency of the thin pipe, and realizing the stretching of small-size blank pipes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drawing forming thin tube parts, and particularly to a drawing forming die and method for drawing forming thin tube parts. BACKGROUND

[0002] A certain produced strip material structure is shown in Figures 1-3 , which comprises a long strip sheet 1, and a plurality of blank tubes 2 are drawing formed on the bottom surface of the long strip sheet 1 and spaced along the length direction thereof. Each blank tube 2 is integrally formed with the long strip sheet 1, the bottom end of the blank tube 2 is closed, the top end of the blank tube 2 is communicated with the outside, the total length of the blank tube 2 is 6.5 mm, the inner diameter is 1 mm, and the outer diameter is 1.2 mm. Technically, it is required to draw each blank tube 2 on the long strip sheet 1 by 1.5 mm, that is, to lengthen the total length of the blank tube 2 from 6.5 mm to 8.0 mm, so as to form the thin tube parts for the customers to use.

[0003] The method for the worker in the workshop to draw each blank tube 2 on the long strip sheet 1 by 1.5 mm is as follows:

[0004] Sa, the worker uses a sleeve 3 to cover the lower end of the first blank tube 2, as shown in Figure 4 ; then the worker inserts a punch 4 into the inner hole of the blank tube 2 from top to bottom, as shown in Figures 5-6 ;

[0005] Sb, the worker knocks the top end of the punch 4 with a wooden hammer, and the knocking direction is shown by the arrow in Figure 6 . Under the knocking, the surrounding material of the blank tube 2 is deformed downward, so as to realize the drawing of the first blank tube 2, and further to correspondingly form the required thin tube part;

[0006] Sc, the worker repeats the steps of Sa~Sb multiple times, so as to draw each blank tube 2 on the long strip sheet 1 downward, and further to correspondingly form the required thin tube part.

[0007] However, the method used in the workshop can draw each blank tube 2 downward, but there are still the following technical defects in the technology:

[0008] In step Sa, since the blank tube 2 itself has a very small size, the worker cannot cover the sleeve 3 on the outside of the blank tube 2 at one time, but needs to cover the sleeve 3 on the outside of the blank tube 2 through multiple covering operations. In step Sb, the worker manually knocks the top end of the punch 4 with a wooden hammer, so as to complete the drawing of the blank tube 2, and further to form the thin tube part. The whole operation is completed by the worker manually, which not only increases the working strength of the worker, but also reduces the forming efficiency of the thin tube part.

[0009] Therefore, there is an urgent need for a forming die and method for forming a thin pipe, which greatly reduces the working intensity of workers and greatly improves the forming efficiency of the thin pipe. SUMMARY

[0010] The present application aims to overcome the shortcomings of the prior art and provide a forming die and method for stretch forming a thin pipe, which greatly reduces the working intensity of workers and greatly improves the forming efficiency of the thin pipe.

[0011] The present application is achieved by the following technical solutions: a forming die for stretch forming a thin pipe, comprising an upper die and a lower die, the upper die comprising an upper holder, an upper pad and a fixed plate sequentially and fixedly arranged on the bottom surface of the upper holder, a limiting plate and a discharging plate sequentially and fixedly arranged below the fixed plate, a gap H being left between the top surface of the limiting plate and the bottom surface of the fixed plate, a second vertical spring fixedly arranged in the upper holder, a second force transmission column fixedly arranged at the bottom end of the second vertical spring, the second force transmission column sequentially and downwardly penetrating the upper holder, the upper pad, the fixed plate, the gap H and being fixedly arranged on the limiting plate, a fixed rod fixedly arranged on the bottom surface of the upper pad, the fixed rod sequentially and downwardly penetrating the fixed plate, the gap H, the limiting plate and extending into the discharging plate, and an extension punch fixedly arranged on the bottom surface of the fixed rod and penetrating the discharging plate.

[0012] The lower die comprises a base, a lower pad and a concave die plate sequentially and fixedly arranged from bottom to top, a concave die insert fixedly arranged in the concave die plate, the top surface of the concave die insert being flush with the top surface of the concave die plate, a small hole being formed in the concave die insert and located directly below the extension punch, and a first vertical spring and a third vertical spring being fixedly arranged in the base and located on both sides of the concave die insert, respectively.

[0013] A first force transmission column and a third force transmission column are fixedly arranged on the top surfaces of the first vertical spring and the third vertical spring, respectively, the first force transmission column and the third force transmission column both upwardly penetrating the lower pad and the concave die plate and extending outside the concave die plate, and the distance between the top surface of the first force transmission column and the top surface of the concave die plate is greater than the distance between the top surface of the third force transmission column and the top surface of the concave die plate.

[0014] The spring force of the third vertical spring is greater than the spring force of the second vertical spring, and the spring force of the second vertical spring is greater than the spring force of the first vertical spring.

[0015] The upper holder of the upper die is fixedly arranged on the stamping head of a stamping machine.

[0016] The diameter of the extension punch is equal to the inner hole diameter of the blank pipe.

[0017] The extension punch and the fixed rod are coaxially arranged.

[0018] A guide hole is formed between the limiting plate and the discharging plate, and the fixed rod and the guide hole are in sliding fit.

[0019] The diameter of the small hole of the concave die insert is equal to the outer diameter of the blank pipe.

[0020] The third force transmission column is located directly below the second force transmission column.

[0021] A method for stretch forming a thin pipe, comprising the following steps:

[0022] S1, pulling the strip from back to front into the area surrounded by the stripper plate and the concave die plate through the pulling mechanism, and preliminarily positioning the first blank pipe of the strip sheet under the stretch punch;

[0023] S2, controlling the punch head of the punch to move downward, the punch head driving the upper support to move downward, the upper support driving the upper pad plate, the fixed plate, the stretch punch, the second vertical spring and the second force transmission column to move downward synchronously, the second force transmission column driving the limiting plate and the stripper plate to move downward synchronously, wherein the stretch punch moves towards the inner hole of the first blank pipe, and at the same time, the stripper plate moves towards the strip sheet;

[0024] S3, as the punch head of the punch continues to move downward, the stretch punch is preliminarily inserted into the inner hole of the blank pipe to realize the guide of the blank pipe, and at the same time, the stripper plate presses the strip sheet onto the top surface of the first force transmission column;

[0025] S4, as the punch head of the punch continues to move downward, the punch head drives the upper support to continue to move downward, the upper support drives the upper pad plate, the fixed plate, the stretch punch, the second vertical spring and the second force transmission column to move downward synchronously, the second force transmission column drives the limiting plate and the stripper plate to move downward synchronously, wherein, as the spring force of the second vertical spring is greater than the spring force of the first vertical spring, the stripper plate presses the strip sheet downward to make it move downward, the strip sheet in turn drives the blank pipe to move towards the small hole of the concave die insert, and at the same time, the strip sheet also presses the first force transmission column downward to make it move downward, the first force transmission column compresses the first vertical spring downward;

[0026] When the strip sheet is blocked by the third force transmission column, the lower end of the blank pipe is inserted into the small hole of the concave die insert to realize the covering of the lower end of the blank pipe, and at the same time, as the spring force of the third vertical spring is greater than the spring force of the second vertical spring, the stripper plate cannot continue to move downward, and at the same time, the strip is clamped and fixed between the stripper plate, the first force transmission column and the third force transmission column;

[0027] S5, with the punch head of the punch machine continuing to move downward, the punch head drives the upper support to continue to move downward, the upper support drives the upper base plate, the fixed plate and the extension punch to move downward relative to the stationary limiting plate and the unloading plate, wherein the second force transmission column is compressed upward, the second vertical spring, at the same time, the gap H between the fixed plate and the limiting plate gradually decreases, at the same time, the extension punch continues to extend downward into the inner hole of the blank pipe; when the gap H between the fixed plate and the limiting plate is reduced to 1.5mm, the extension punch is just completely matched with the inner hole of the blank pipe, at this time, the extension punch is in the extension position;

[0028] S6, with the punch head of the punch machine continuing to move downward, the punch head drives the upper support to continue to move downward, the upper support drives the upper base plate, the fixed plate and the extension punch to move downward relative to the stationary limiting plate and the unloading plate, wherein the extension punch presses the bottom closed end of the blank pipe downward, the extension punch gradually extends the blank pipe downward, at the same time, the gap H between the fixed plate and the limiting plate gradually decreases; when the bottom surface of the fixed plate just presses on the top surface of the limiting plate, the extension punch just extends the blank pipe downward by 1.5mm, and then a thin pipe with a total length of 8mm is formed;

[0029] S7, after forming, the punch head of the punch machine is controlled to reset upward, the punch head drives the upper support to move upward, the upper support drives the upper base plate, the fixed plate, the extension punch, the second vertical spring and the second force transmission column to move upward synchronously, under the elastic restoring force of the second vertical spring, the second force transmission column resets, and then under the elastic restoring force of the first vertical spring, the first force transmission column resets;

[0030] S8, the worker repeats the operation of steps S1-S7 multiple times, so that each blank pipe on the long strip plate is extended downward, and then the corresponding thin pipe with the required length is formed.

[0031] The present application has the following advantages: greatly reducing the working intensity of workers, and greatly improving the forming efficiency of thin pipes. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structure schematic diagram of the strip;

[0033] Figure 2 It is Figure 1 A-A sectional view of;

[0034] Figure 3 It is Figure 2 B part local enlarged view of;

[0035] Figure 4 It is a schematic diagram that the worker uses a sleeve to cover the lower end of the first blank pipe;

[0036] Figure 5 It is a schematic diagram that the worker inserts the punch from top to bottom into the inner hole of the blank pipe;

[0037] Figure 6 Fig. 4 is a partial enlarged view of part C of Fig. 3; Figure 5

[0038] Figure 7 Fig. 6 is a schematic view of the structure of the present application;

[0039] Figure 8 Fig. 7 is a schematic view of the connection between the fixed rod and the extension punch;

[0040] Figure 9 Fig. 8 is a schematic view of the structure of the stripper plate;

[0041] Figure 10 Fig. 9 is a schematic view of the structure of the recess insert;

[0042] Figure 11 Fig. 10 is a schematic view of the initial positioning of the first blank tube of the long strip sheet with material directly below the extension punch;

[0043] Figure 12 Fig. 11 is a schematic view of the initial insertion of the extension punch into the inner hole of the blank tube;

[0044] Figure 13 Fig. 13 is a partial enlarged view of part D of Fig. 12; Figure 12

[0045] Figure 14 Fig. 15 is a schematic view of the insertion of the lower end of the blank tube into the small hole of the recess insert;

[0046] Figure 15 Fig. 17 is a partial enlarged view of part E of Fig. 16; Figure 14

[0047] Figure 16 Fig. 19 is a schematic view of the complete fitting of the extension punch and the inner hole of the blank tube;

[0048] Figure 17 Fig. 21 is a partial enlarged view of part F of Fig. 20; Figure 16 Fig. 23 is a schematic view of the structure of the present application;

[0049]

[0050] 1 - long strip sheet, 2 - blank tube, 3 - sleeve, 4 - punch;

[0051] 5 - upper support, 6 - upper backing plate, 7 - fixed plate, 8 - limiting plate, 9 - stripper plate, 10 - gap H, 11 - second vertical spring, 12 - second force transmission column, 13 - fixed rod, 14 - extension punch;

[0052] 15 - base, 16 - lower backing plate, 17 - recess plate, 18 - recess insert, 19 - small hole, 20 - first vertical spring, 21 - third vertical spring, 22 - first force transmission column, 23 - third force transmission column, 24 - guide hole.​​​​ Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the following description:

[0054] like Figures 7-10 As shown, a forming mold for drawing out thin tubular parts includes an upper mold and a lower mold. The upper mold includes an upper support 5, an upper pad 6 and a fixing plate 7 sequentially fixed to the bottom surface of the upper support 5. A limiting plate 8 and a stripping plate 9 sequentially fixed together are arranged below the fixing plate 7. A gap H10 is left between the top surface of the limiting plate 8 and the bottom surface of the fixing plate 7. A second vertical spring 11 is fixed inside the upper support 5. A second force transmission column 12 is fixed at the bottom end of the second vertical spring 11. 12 passes downwards sequentially through the upper support 5, upper pad 6, fixing plate 7, and gap H10, and is fixed to the limiting plate 8. A fixing rod 13 is fixed on the bottom surface of the upper pad 6, passing downwards sequentially through the fixing plate 7, gap H10, and limiting plate 8, and extending into the unloading plate 9. An extending punch 14, passing downwards through the unloading plate 9, is fixed on the bottom surface of the fixing rod 13. The extending punch 14 is coaxially arranged with the fixing rod 13, and the diameter of the extending punch 14 is equal to the inner diameter of the blank tube 2. The upper support 5 of the upper die is fixed to the stamping head of the stamping machine.

[0055] The lower mold includes a base 15, a lower pad 16, and a concave template 17, which are fixed together from bottom to top. A concave template 17 has a concave mold insert 18 fixed inside. The top surface of the concave mold insert 18 is flush with the top surface of the concave template 17. A small hole 19 is opened in the concave mold insert 18, located directly below the extending punch 14. A first vertical spring 20 and a third vertical spring 21 are fixed inside the base 15, located on both sides of the concave mold insert 18. The diameter of the small hole 19 in the concave mold insert 18 is equal to the outer diameter of the blank tube 2.

[0056] A first force transmission column 22 and a third force transmission column 23 are respectively fixed on the top surfaces of the first vertical spring 20 and the third vertical spring 21. Both the first force transmission column 22 and the third force transmission column 23 penetrate upward through the lower pad 16 and the concave template 17 and extend outside the concave template 17. The distance between the top surface of the first force transmission column 22 and the top surface of the concave template 17 is greater than the distance between the top surface of the third force transmission column 23 and the top surface of the concave template 17. The spring force of the third vertical spring 21 is greater than the spring force of the second vertical spring 11, and the spring force of the second vertical spring 11 is greater than the spring force of the first vertical spring 20.

[0057] A guide hole 24 is provided between the limiting plate 8 and the unloading plate 9, and the fixing rod 13 is slidably engaged with the guide hole 24. The third force transmission column 23 is located directly below the second force transmission column 12.

[0058] A method for stretch forming a thin-walled tube, comprising the steps of:

[0059] S1, pulling the strip material shown in Figures 1-3 from back to front into the area surrounded by the stripper plate 9 and the die plate 17, and initially positioning the first blank tube 2 of the long strip sheet 1 directly below the stretch punch 14, as shown in Figure 11 ;

[0060] S2, controlling the punch head of the punch to move downward, the punch head driving the upper support 5 to move downward, the upper support 5 driving the upper cushion plate 6, the fixed plate 7, the stretch punch 14, the second vertical spring 11 and the second force transmission column 12 to move downward synchronously, the second force transmission column 12 driving the limiting plate 8 and the stripper plate 9 to move downward synchronously, wherein the stretch punch 14 moves towards the inner hole of the first blank tube 2, and at the same time, the stripper plate 9 moves towards the long strip sheet 1;

[0061] S3, as the punch head of the punch continues to move downward, the stretch punch 14 is initially inserted into the inner hole of the blank tube 2, as shown in Figures 12-13 , to realize the guiding of the blank tube 2, and at the same time, the stripper plate 9 presses the long strip sheet 1 onto the top surface of the first force transmission column 22;

[0062] S4, as the punch head of the punch continues to move downward, the punch head drives the upper support 5 to continue to move downward, the upper support 5 drives the upper cushion plate 6, the fixed plate 7, the stretch punch 14, the second vertical spring 11 and the second force transmission column 12 to move downward synchronously, the second force transmission column 12 drives the limiting plate 8 and the stripper plate 9 to move downward synchronously, wherein, due to the spring force of the second vertical spring 11 being greater than the spring force of the first vertical spring 20, the stripper plate 9 presses the long strip sheet 1 downward to make it move downward, and the long strip sheet 1 drives the blank tube 2 to move towards the small hole 19 of the die insert 18, at the same time, the long strip sheet 1 also presses the first force transmission column 22 downward to make it move downward, and the first force transmission column 22 compresses the first vertical spring 20 downward;

[0063] When the long strip sheet 1 is blocked by the third force transmission column 23, the lower end of the blank tube 2 is inserted into the small hole 19 of the die insert 18, as shown in Figures 14-15 , to realize the covering of the lower end of the blank tube 2, and at the same time, due to the spring force of the third vertical spring 21 being greater than the spring force of the second vertical spring 11, the stripper plate 9 cannot continue to move downward, and at the same time, the strip material is clamped and fixed between the stripper plate 9, the first force transmission column 22 and the third force transmission column 23;

[0064] S5, with the punch head of the punch machine continuing to move downward, the punch head drives the upper support 5 to continue to move downward, the upper support 5 drives the upper pad plate 6, the fixed plate 7 and the extension punch 14 to move downward relative to the stationary limiting plate 8 and the unloading plate 9, wherein the second transmission column 12 is compressed upwardly the second vertical spring 11, at the same time, the gap H between the fixed plate 7 and the limiting plate 8 gradually decreases, at the same time, the extension punch 14 continues to extend downwardly into the inner hole of the blank pipe 2; when the gap H between the fixed plate 7 and the limiting plate 8 decreases to 1.5mm, the extension punch 14 is just completely matched with the inner hole of the blank pipe 2, as shown in Figures 16-17 Fig. 5, at this time, the extension punch 14 is in the extension station;

[0065] S6, with the punch head of the punch machine continuing to move downward, the punch head drives the upper support 5 to continue to move downward, the upper support 5 drives the upper pad plate 6, the fixed plate 7 and the extension punch 14 to continue to move downward relative to the stationary limiting plate 8 and the unloading plate 9, wherein the extension punch 14 presses the bottom closed end of the blank pipe 2 downwardly, the extension punch 14 gradually extends the blank pipe 2 downwardly, at the same time, the gap H between the fixed plate 7 and the limiting plate 8 gradually decreases; when the bottom surface of the fixed plate 7 just presses on the top surface of the limiting plate 8, the extension punch 14 just extends the blank pipe 2 downwardly by 1.5mm, and then forms the thin pipe with the total length of 8mm;

[0066] S7, after the forming, the punch head of the punch machine is controlled to reset upwardly, the punch head drives the upper support 5 to move upwardly, the upper support 5 drives the upper pad plate 6, the fixed plate 7, the extension punch 14, the second vertical spring 11 and the second transmission column 12 to move upwardly synchronously, under the elastic restoring force of the second vertical spring 11, the second transmission column 12 resets, and then under the elastic restoring force of the first vertical spring 20, the first transmission column 22 resets;

[0067] S8, the worker repeats the operation of steps S1-S7 for many times, that is, each blank pipe 2 on the long strip sheet 1 can be extended downwardly, and then the thin pipe with the required length is correspondingly formed.

[0068] As can be seen from steps S1-S7, the worker only needs to preliminarily position the blank pipe 2 of the long strip sheet 1 directly below the extension punch 14, and then controls the punch head of the punch machine to move downwardly, that is, the blank pipe 2 can be guided and corrected, the lower end of the blank pipe 2 can be covered, the extension punch 14 can enter the extension station, the extension punch 14 can extend the blank pipe 2 downwardly by 1.5mm, and then the thin pipe with the required length is formed.

[0069] Therefore, compared with the forming method in the workshop, the forming die does not need workers to put the sleeve on the outside of the blank pipe 2, nor does it need workers to manually knock the top end of the punch with a wooden hammer to complete the extension of the blank pipe 2, but only needs the downward movement of the upper support 5 of the upper die driven by the punch head of the punch machine to automatically extend the blank pipe 2 by 1.5 mm. This not only greatly reduces the working intensity of the workers, but also realizes the extension of a blank pipe 2 in a short time, and further realizes the extension of all blank pipes 2 on the long strip sheet 1 in a short time, thereby greatly improving the forming efficiency of the thin pipe.

Claims

1. A forming die for drawing out thin tubular parts, characterized in that: It includes an upper mold and a lower mold. The upper mold includes an upper support (5), an upper pad (6) and a fixing plate (7) sequentially fixed on the bottom surface of the upper support (5). A limiting plate (8) and a stripper plate (9) sequentially fixed together are provided below the fixing plate (7). A gap H (10) is left between the top surface of the limiting plate (8) and the bottom surface of the fixing plate (7). A second vertical spring (11) is fixed inside the upper support (5). A second force transmission column is fixed at the bottom end of the second vertical spring (11). (12) The second force transmission column (12) passes through the upper support (5), upper pad (6), fixed plate (7), and gap H (10) in sequence downwards and is fixed on the limiting plate (8). A fixed rod (13) is fixed on the bottom surface of the upper pad (6) and passes through the fixed plate (7), gap H (10), and limiting plate (8) in sequence downwards and extends into the unloading plate (9). An extension punch (14) that passes through the unloading plate (9) in sequence downwards is fixed on the bottom surface of the fixed rod (13). The lower mold includes a base (15), a lower pad (16), and a concave template (17) that are fixed together from bottom to top. A concave template (17) is fixedly provided with a concave mold insert (18). The top surface of the concave mold insert (18) is flush with the top surface of the concave template (17). A small hole (19) located directly below the extending punch (14) is opened in the concave mold insert (18). A first vertical spring (20) and a third vertical spring (21) located on both sides of the concave mold insert (18) are fixedly provided in the base (15). The first vertical spring (20) and the third vertical spring (21) are respectively fixed with a first force transmission column (22) and a third force transmission column (23). The first force transmission column (22) and the third force transmission column (23) both penetrate upward through the lower pad (16) and the concave template (17) and extend outside the concave template (17). The distance between the top surface of the first force transmission column (22) and the top surface of the concave template (17) is greater than the distance between the top surface of the third force transmission column (23) and the top surface of the concave template (17). The spring force of the third vertical spring (21) is greater than the spring force of the second vertical spring (11), and the spring force of the second vertical spring (11) is greater than the spring force of the first vertical spring (20). The method for forming a thin tubular component using a molding die includes the following steps: S1. The strip material is pulled from back to front into the area enclosed by the unloading plate (9) and the concave plate (17) by the pulling mechanism, and the first blank tube (2) of the long strip thin plate (1) is initially positioned directly below the extending punch (14). The total length of the blank tube 2 is 6.5mm, its inner diameter is 1mm, and its outer diameter is 1.2mm. S2. Control the punch head of the press to move downward. The punch head drives the upper support (5) to move downward. The upper support (5) drives the upper pad (6), the fixed plate (7), the extending punch (14), the second vertical spring (11), and the second force transmission column (12) to move downward synchronously. The second force transmission column (12) drives the limiting plate (8) and the unloading plate (9) to move downward synchronously. The extending punch (14) moves toward the inner hole of the first blank tube (2). At the same time, the unloading plate (9) moves toward the long strip thin plate (1). S3. As the punch head of the press continues to move downward, the extension punch (14) is initially inserted into the inner hole of the blank tube (2) to guide the blank tube (2). At the same time, the strip plate (9) presses the long strip plate (1) onto the top surface of the first force transmission column (22). S4. As the punch head of the press continues to move downward, the punch head drives the upper support (5) to continue moving downward. The upper support (5) drives the upper pad (6), the fixed plate (7), the extension punch (14), the second vertical spring (11), and the second force transmission column (12) to move downward synchronously. The second force transmission column (12) drives the limiting plate (8) and the unloading plate (9) to move downward synchronously. Since the spring force of the second vertical spring (11) is greater than the spring force of the first vertical spring (20), the unloading plate (9) presses down on the long strip plate (1) to make it move downward. The long strip plate (1) also drives the blank tube (2) to move towards the small hole (19) of the die insert (18). At the same time, the long strip plate (1) also presses down on the first force transmission column (22) to make it move downward. The first force transmission column (22) compresses the first vertical spring (20) downward. When the long strip plate (1) is blocked by the third force transmission column (23), the lower end of the blank tube (2) is inserted into the small hole (19) of the die insert (18) to cover the lower end of the blank tube (2). At the same time, since the spring force of the third vertical spring (21) is greater than the spring force of the second vertical spring (11), the unloading plate (9) cannot continue to move downward. Meanwhile, the strip is clamped and fixed between the unloading plate (9), the first force transmission column (22) and the third force transmission column (23). S5. As the punch head of the press continues to move downward, the punch head drives the upper support (5) to continue moving downward. The upper support (5) drives the upper pad (6), the fixed plate (7), and the extending punch (14) to move downward relative to the stationary limiting plate (8) and the unloading plate (9). Among them, the second force transmission column (12) compresses the second vertical spring (11) upward. At the same time, the gap H between the fixed plate (7) and the limiting plate (8) gradually decreases. Meanwhile, the extending punch (14) continues to extend downward into the inner hole of the blank tube (2). When the gap H between the fixed plate (7) and the limiting plate (8) decreases to 1.5mm, the extending punch (14) is just fully fitted with the inner hole of the blank tube (2). At this time, the extending punch (14) is in the extending position. S6. As the punch head of the press continues to move downward, the punch head drives the upper support (5) to continue moving downward. The upper support (5) drives the upper pad (6), the fixed plate (7), and the extending punch (14) to continue moving downward relative to the stationary limiting plate (8) and the unloading plate (9). The extending punch (14) presses down on the bottom closed end of the blank tube (2). The extending punch (14) gradually extends the blank tube (2) downward. At the same time, the gap H between the fixed plate (7) and the limiting plate (8) gradually decreases. When the bottom surface of the fixed plate (7) just presses against the top surface of the limiting plate (8), the extending punch (14) just extends the blank tube (2) downward by 1.5mm, thus forming a thin tube with a total length of 8mm. S7. After forming, control the punch head of the press to return to the upper position. The punch head drives the upper support (5) to move upward. The upper support (5) drives the upper pad (6), the fixed plate (7), the extension punch (14), the second vertical spring (11) and the second force transmission column (12) to move upward synchronously. Under the elastic restoring force of the second vertical spring (11), the second force transmission column (12) returns to the position. Then, under the elastic restoring force of the first vertical spring (20), the first force transmission column (22) returns to the position. S8. The worker repeats steps S1 to S7 multiple times to extend each blank tube (2) on the long thin plate (1) downwards, thereby forming the corresponding thin tube of the required length.

2. A forming die for drawing out thin tubular parts according to claim 1, characterized in that: The upper support (5) of the upper die is fixed to the stamping head of the stamping machine.

3. A forming die for drawing out thin tubular parts according to claim 2, characterized in that: The diameter of the extending punch (14) is equal to the inner diameter of the blank tube (2).

4. A forming die for drawing out thin tubular parts according to claim 3, characterized in that: The extending punch (14) is coaxially arranged with the fixing rod (13).

5. A forming die for drawing out thin tubular parts according to claim 4, characterized in that: A guide hole (24) is provided between the limiting plate (8) and the unloading plate (9), and the fixing rod (13) slides in conjunction with the guide hole (24).

6. A forming die for drawing out thin tubular parts according to claim 5, characterized in that: The diameter of the small hole (19) of the die insert (18) is equal to the outer diameter of the blank tube (2).

7. A forming die for drawing out thin tubular parts according to claim 6, characterized in that: The third force transmission column (23) is located directly below the second force transmission column (12).

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