A process for reducing a tube using an equal wall thickness reducing die

Abstract

The application discloses a pipe reducing process using an equal-wall-thickness pipe reducing die, and the pipe reducing die is a binary structure and is composed of a unary unit and a binary unit, the maximum distance between the two units forms a sliding unary distance, the binary structure can realize smooth pipe reducing of a pipe blank into the die and core rod pulling for trimming the wall thickness of the pipe blank, the unary distance is closed to make the head of the die core rod move forward to the entry expansion of the die, and sufficient clearance is ensured for the pipe blank entering the die; when the die is withdrawn, the unary distance is opened, the position of the head of the die core rod is followed to move backward to the straight section of the die core, and the original wall thickness of the pipe blank is ensured after pipe reducing. Thus, the problems existing in the large-scale equal-wall-thickness cold extrusion pipe reducing of low-carbon seamless steel pipes and other workpieces are effectively solved, the material utilization rate of the product can reach more than 95%, and the pipe reducing ratio can reach more than 2.5. The die adopts the binary structure design, the power mechanism composition can be reduced, and the efficiency, quality and cost of batch production can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal workpiece processing, and in particular to a pipe shrinking die and pipe shrinking process for pipe shrinking forming of metal pipe fittings. BACKGROUND

[0002] Metal tubular hollow products are applied in many fields. Generally, the products are initially formed into initial pipe blanks, and then the pipe shrinking process is performed on the pipe blanks by a pipe shrinking machine in cooperation with a pipe shrinking die to obtain finished pipe blanks. However, for low-carbon seamless steel pipes and other products with a small self-stretching coefficient, it is a common practice in the industry to reduce the diameter of the pipes by cold extrusion. However, the current industry pipe shrinking ratio is only about 1.5, which cannot meet the use requirements of many fields. Moreover, the current process cannot achieve large-scale pipe shrinking (generally, the pipe shrinking ratio needs to reach about 2.5 to be considered large-scale pipe shrinking) without increasing or reducing the wall thickness of the pipe, that is, it is difficult to achieve large-scale pipe shrinking with equal wall thickness. SUMMARY

[0003] The present application aims to solve the technical problems of the prior art and provide a pipe shrinking process using an equal-wall-thickness pipe shrinking die, which has a simple die structure, a more reasonable design, and can achieve equal-wall-thickness pipe shrinking forming of workpieces made of low-stretching-system materials such as carbon steel pipes.

[0004] To solve the above technical problems, the present application adopts the following technical solution: an equal-wall-thickness pipe shrinking die is slidably installed on a pipe shrinking device, characterized in that: the pipe shrinking die comprises a unary unit and a binary unit, the binary unit is arranged outside the unary unit, and the two are slidably installed on the pipe shrinking device to form a binary structure with synchronous sliding process and independent sliding process, wherein the sliding distance of the binary unit is greater than the sliding distance of the unary unit, and the excess sliding distance of the binary unit forms a unary distance, which is also the maximum distance between the unary unit and the binary unit in the independent sliding process.

[0005] The unary unit comprises a pipe shrinking die core, which is installed at the front end of a sliding support body to form a structure that can move synchronously with the sliding support body. The sliding support body has a forming cavity, and a die core rod is inserted into the forming cavity. The tail end of the die core rod is installed on the binary unit to form a structure that can move synchronously with the binary unit. The binary unit is connected to a driving mechanism, which drives the binary unit to slide and drives the unary unit to move through the binary unit to complete the pipe shrinking forming.

[0006] The inner cavity of the tube reduction mold core includes a flaring section and a straight section, the flaring section is located at the front end and faces the tube blank, and the straight section is located at the rear end and docked with the tail of the flaring section; the minimum inner diameter of the flaring section is larger than the outer diameter of the tube blank, and the inner diameter of the straight section is equivalent to the outer diameter of the tube blank; when the mold core rod is in the mold open state, its head is located in the straight section of the tube reduction mold core, and the minimum distance between the outer surface of the mold core rod head and the inner wall of the straight section of the tube reduction mold core is the same as the wall thickness of the tube blank; when the tube reduction mold is closed, the binary unit and the unary unit fit together, the head of the mold core rod enters the flaring section of the tube reduction mold core, and the distance between the head of the mold core rod and the inner wall of the flaring section is larger than the wall thickness of the tube blank.

[0007] Furthermore, the expansion section of the tube reduction mold core is a conical structure that gradually shrinks inward, and the head of the mold core rod is a thickening head with a diameter larger than the diameter of the main part of the mold core rod. The thickening head can be set to have a front section in the shape of a round rod and a rear section in the shape of a gradually tapering cone, and the tapered part is then connected to the main part of the mold core rod; the thickening head is located in the straight section of the tube reduction mold core in the mold open state, and the minimum distance between the outer surface of the thickening head and the inner wall of the straight section of the tube reduction mold core is the same as the wall thickness of the tube blank; when the tube reduction mold is closed, the binary unit and the unary unit fit together, and the thickening head enters the expansion section of the tube reduction mold core, and the distance between the thickening head and the inner wall of the expansion section is greater than the wall thickness of the tube blank.

[0008] Furthermore, the sliding support body is installed on a first support seat, and the first support seat is installed on the guide rail of the tube shrinking device through a sliding block.

[0009] Furthermore, the binary unit includes a second support base, which is installed on the guide rail through another slider and is located outside the first support base.

[0010] Furthermore, the binary unit also includes a cooling mechanism, which extends into the molding cavity of the sliding support body and is aligned with the mold core rod and the tube blank inserted into the molding cavity.

[0011] Furthermore, the cooling mechanism includes a water inlet pipe and a cooling pipeline. The water inlet pipe is arranged on the second support seat. The cooling pipeline is connected to the water inlet pipe and extends through the second support seat to the molding cavity. A water nozzle is installed at the outlet of the cooling pipeline through the water channel cover plate. The water nozzle is aimed at the mold core rod and the tube blank inserted into the molding cavity, and cooling water or coolant is sprayed onto the tube blank and inside the mold through the water nozzle.

[0012] Furthermore, the second support seat is connected to the side cylinder rod of the side cylinder serving as the driving mechanism through a side cylinder flange, and the linear distance is the maximum distance generated when the second support seat and the first support seat slide relative to each other.

[0013] Preferably, a set of pipe reducing dies is arranged on each side of the pipe blank, and the pipe reducing dies on the two sides are symmetrically arranged. This arrangement is mainly for the workpiece that needs to be reduced on both sides at the same time.

[0014] A pipe reducing process based on the foregoing equal-wall-thickness pipe reducing die, characterized in that the following steps are performed,

[0015] Step 1: Place the pipe blank into the jig of the pipe reducing device.

[0016] Step 2: The pipe reducing device clamps the middle shape of the pipe blank under the control of the numerical control system, and the side cylinders push the pipe reducing dies to start reducing the pipe blank under the control of the system.

[0017] Step 3: The side cylinder rod pushes the pipe reducing die to move towards the pipe blank, so that the die core rod and the pipe reducing die core also move towards the pipe blank. When the pipe reducing die core contacts the pipe blank, due to the pipe blank into the mold resistance, the one-encoding unit slides backward under the resistance, and the sliding distance reaches the encoding distance after being combined with the two-encoding unit. At this time, the thickening head of the die core rod protrudes into the flared section of the pipe reducing die core, and since the gap here is larger than the gap in the straight cylinder section, the pipe blank can smoothly pass through the pipe reducing die core into the forming cavity when it is introduced into the pipe reducing die.

[0018] Step 4: During the process of the pipe blank entering the forming cavity, the wall thickness of the pipe blank increases and becomes irregularly shaped due to the extrusion of the pipe reducing die core and the die core rod.

[0019] Step 5: After the pipe blank reaches the set length and completely enters the pipe reducing die, the two-encoding unit starts to retreat under the drive of the side cylinder rod. At this time, the one-encoding unit remains stationary due to the friction with the pipe blank, and is pulled away to the encoding distance under the retreat action of the two-encoding unit, while the thickening head of the die core rod is pulled back to the straight cylinder section of the pipe reducing die core. This process is the two-encoding action.

[0020] Step 6: The two-encoding unit continues to retreat, driving the one-encoding unit to start the overall pullback of the pipe reducing die. Since the gap between the thickening head of the die core rod and the inner wall of the straight cylinder section of the pipe reducing die core is the same as the original wall thickness of the pipe blank, the pullback of the die core rod causes the increased wall thickness of the pipe blank to be thinned back to the original thickness.

[0021] Step 7: After the overall retreat action of the pipe reducing die is completed, the pipe blank returns to the original wall thickness and is smooth and flat overall, and the cooling system is turned off, and the pipe reducing is completed. Of course, the entire pipe reducing process can be divided into several processes (such as three processes), and each process completes a certain pipe reducing process. After all processes are completed, the final pipe reducing forming of the pipe blank is realized.

[0022] Further, the pipe blank enters and exits the inside of the pipe reducing die, and the pipe reducing die and the pipe blank are lubricated and cooled by the water jet nozzle, so that the pipe reducing process is smoothly performed and the die is protected.

[0023] The pipe reducing die is designed as a binary structure, which is composed of a unary unit and a binary unit, and the maximum distance between the two units forms a sliding unary distance. The die is pushed forward to reduce the pipe by a large proportion, and the core is retracted to ensure the equal wall thickness. The binary structure can realize smooth entry of the pipe blank into the die for pipe reducing and retraction of the core for trimming the wall thickness of the pipe blank. The opening of the unary distance is mainly reflected in the position change of the working position of the core head. The closing of the unary distance makes the die core head move forward to the entry expansion position, so that the pipe blank has enough gap when entering the die. When the die is retracted, the unary distance is pulled open, and the die core head position is moved backward to the straight section of the die core, so that the pipe blank maintains the original wall thickness after pipe reducing.

[0024] Thus, the problems of large-scale equal-wall-thickness cold extrusion pipe reducing of low-carbon seamless steel pipes and other workpieces in the industry are effectively solved. The material utilization rate of the product can reach more than 95%, and the pipe reducing ratio can reach more than 2.5. The die itself has a cooling and lubricating circulation mechanism, and is modularly designed, so that it is easy to replace and maintain, and can change the inefficient, dirty and messy manufacturing environment in the industry. The die is designed with a binary structure, which can reduce the composition of the power mechanism, is conducive to miniaturization and simplification, and can realize the effect of one power completing four actions in two directions. The efficiency, quality and cost of batch production are improved in quality, and the die is suitable for automatic production and can realize pollution-free, standardized and automated modern production. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Fig. 1 is a schematic diagram of the change of the pipe reducing die in the forming process of the present application from closing to opening;

[0026] Figure 2 Fig. 2 is a structural schematic diagram of the pipe reducing die of the present application;

[0027] Figure 3 Fig. 3 is a partial enlarged view of Figure 2 ;

[0028] Figure 4 Fig. 4 is a schematic diagram of the change of the pipe reducing die and the pipe blank in the forming process of the present application;

[0029] Figure 5 Fig. 5 is a schematic diagram of the installation of the pipe reducing die in the pipe reducing machine;

[0030] Figure 6 Fig. 6 is a schematic diagram of the change of the pipe blank in the forming process of the present application.

[0031] In the figure, A is a decimal unit, B is a binary unit, 1 is a water inlet pipe, 2 is a cooling pipe, 3 is a water pipe cover plate, 4 is a water nozzle, 5 is a mold core rod, 6 is a pipe reducing mold core, 61 is an expanding section, 62 is a straight section, 7 is a sliding support body, 71 is a forming cavity, 8 is a first support seat, 9 is a second support seat, 10 is a side cylinder rod, 11 is a sliding block, 12 is a guide rail, 13 is a side cylinder flange, and 14 is a pipe blank. DETAILED DESCRIPTION

[0032] In this embodiment, referring to Figures 1-6 , the equal-wall-thickness pipe reducing mold is installed in a slidable structure on a pipe reducing device (such as a pipe reducing machine), and the pipe reducing mold comprises a decimal unit A and a binary unit B, the binary unit B is arranged outside the decimal unit A, and the two are slidably installed on the pipe reducing device to form a binary structure with synchronous sliding process and independent sliding process, wherein the sliding distance of the binary unit B is greater than that of the decimal unit A, and the extra sliding distance of the binary unit B forms a decimal distance L4, which is also the maximum distance between the decimal unit A and the binary unit B in the independent sliding process;

[0033] The decimal unit A comprises a pipe reducing mold core 6, which is installed at the front end of a sliding support body 7 to form a structure that can move synchronously with the sliding support body 7. The sliding support body 7 has a forming cavity 71 therein, and a mold core rod 5 is inserted into the forming cavity 71. The tail end of the mold core rod 5 is installed on the binary unit B to form a structure that can move synchronously with the binary unit B. The binary unit B is connected with a driving mechanism, which drives the binary unit B to slide and drives the decimal unit A to move through the binary unit B to complete the pipe reducing forming.

[0034] The inner cavity of the pipe reducing mold core 6 comprises an expanding section 61 and a straight section 62. The expanding section 61 is located at the front end and faces the pipe blank 14, and the straight section 62 is located at the rear end and is in abutment with the tail of the expanding section 61. The minimum inner diameter of the expanding section 61 is greater than the outer diameter of the pipe blank 14, and the inner diameter of the straight section 62 is equivalent to the outer diameter of the pipe blank 14 (at the pipe reducing position). When the mold is opened, the head of the mold core rod 5 is located in the straight section 62 of the pipe reducing mold core 6, and the minimum distance between the outer surface of the head of the mold core rod 5 and the inner wall of the straight section 62 of the pipe reducing mold core 6 is the same as / equivalent to the wall thickness H of the pipe blank 14. When the pipe reducing mold is closed, the binary unit B and the decimal unit A are in close contact with each other, the head of the mold core rod 5 enters the expanding section 61 of the pipe reducing mold core 6, and the distance between the head of the mold core rod 5 and the inner wall of the expanding section 61 is greater than the wall thickness H of the pipe blank 14.

[0035] The flared section 61 of the necking die core 6 is a tapered structure that gradually narrows inward, and the head of the die core rod 5 is a thickened head with a diameter larger than that of the main body of the die core rod 5. The thickened head can be provided with a front section in the shape of a round rod and a rear section in the shape of a tapered structure that gradually narrows, and the tapered structure is connected to the main body of the die core rod 5. The thickened head is located in the straight section 62 of the necking die core 6 when the mold is open, and the minimum distance between the outer surface of the thickened head and the inner wall of the straight section 62 of the necking die core 6 is the same as the wall thickness H of the pipe blank 14. When the necking die is closed, the binary unit B and the unary unit A are in close contact with each other, the thickened head enters the flared section 61 of the necking die core 6, and the distance between the thickened head and the inner wall of the flared section 61 is greater than the wall thickness H of the pipe blank 14.

[0036] The sliding support body 7 is mounted on the first support seat 8, and the first support seat 8 is mounted on the guide rail 12 of the necking device through a sliding block 11.

[0037] The binary unit B includes a second support seat 9 mounted on the guide rail 12 through another sliding block 11 and located outside the first support seat 8.

[0038] The binary unit B also includes a cooling mechanism that extends into the forming cavity 71 of the sliding support body 7 and is aligned with the die core rod 5 and the pipe blank 14 inserted into the forming cavity 71.

[0039] The cooling mechanism includes a water inlet pipe 1 provided on the second support seat 9 and a cooling pipe 2 connected to the water inlet pipe 1 and extending through the second support seat 9 to the forming cavity 71. A water jet nozzle 4 is installed at the outlet of the cooling pipe 2 through a water path cover plate 3, and the water jet nozzle 4 is aligned with the die core rod 5 and the pipe blank 14 inserted into the forming cavity 71. Cooling water or coolant is sprayed onto the pipe blank 14 and inside the mold through the water jet nozzle 4.

[0040] The second support seat 9 is connected to the side cylinder rod 10 of the side cylinder as a driving mechanism through a side cylinder flange 13, and the decimal distance L4 is the maximum distance between the second support seat 9 and the first support seat 8 when they slide relative to each other.

[0041] A set of necking dies is provided on the left and right sides of the pipe blank 14, and the necking dies on both sides are symmetrically arranged. This arrangement is mainly for workpieces that require necking forming on both sides at the same time.

[0042] Based on the necking process of the equal-wall-thickness necking die described above, the following steps are taken,

[0043] Step 1, place the pipe blank 14 into the jig (lower forming die) of the necking device;

[0044] Step 2, the middle part of the pipe blank 14 is clamped by the pipe reducing device under the control of the numerical control system, and the left and right side cylinders push the pipe reducing die to start reducing the pipe blank 14 under the control of the system;

[0045] Step 3, the side cylinder rod 10 pushes the pipe reducing die to move towards the pipe blank 14, so that the die core rod 5 and the pipe reducing die core 6 also move towards the pipe blank 14; when the pipe reducing die core 6 contacts the pipe blank 14, due to the effect of the mold entry resistance of the pipe blank 14, the first feeding unit A slides backward under the resistance, and after the sliding distance reaches the feeding distance L4, the first feeding unit A is attached to the second feeding unit B; at this time, the thickening head of the die core rod 5 extends into the flared section 61 of the pipe reducing die core 6, and since the gap at this position is larger than the gap in the straight cylinder section 62, the pipe blank 14 can smoothly pass through the pipe reducing die core 6 and enter the forming cavity 71 when the pipe blank 14 is guided into the pipe reducing die;

[0046] Step 4, during the process of the pipe blank 14 entering the forming cavity 71, the wall thickness H of the pipe blank 14 increases to H1 and becomes a wavy irregular shape due to the extrusion of the pipe reducing die core 6 and the die core rod 5;

[0047] Step 5, after the pipe blank 14 reaches the set length and completely enters the pipe reducing die, the second feeding unit B starts to retreat under the drive of the side cylinder rod 10; at this time, the first feeding unit A remains stationary due to the friction with the pipe blank 14, and is pulled away to the feeding distance L4 under the retreat action of the second feeding unit B, and at the same time, the thickening head of the die core rod 5 is pulled back to the straight cylinder section 62 of the pipe reducing die core 6, which is the binary action;

[0048] Step 6, the second feeding unit B continues to retreat, driving the first feeding unit A to start the overall pullback of the pipe reducing die, and since the gap between the thickening head of the die core rod 5 and the inner wall of the straight cylinder section 62 of the pipe reducing die core 6 is the same as the original wall thickness H of the pipe blank 14, the pullback of the die core rod 5 causes the increased wall thickness H1 of the pipe blank 14 to be reduced to the original thickness H;

[0049] Step 7, after the overall retreat action of the pipe reducing die is completed, the pipe blank 14 returns to the original wall thickness H and is smooth and flat, the cooling system is turned off, and the pipe reducing is completed.

[0050] The pipe reducing die and the pipe blank 14 are lubricated and cooled by the water jet nozzle 4 when the pipe blank 14 enters and exits the inside of the pipe reducing die, to ensure smooth pipe reducing process and protect the die.

[0051] Of course, the entire pipe reducing process can be divided into several (such as three) procedures, each procedure completes a certain pipe reducing process, and after all procedures are completed, the final pipe reducing and forming of the pipe blank is realized.

[0052] The following is a further description of three procedures:

[0053] 1) the length L of the pipe blank 14 is increased to L1 by the pipe shrinking die of the first station, and the first pipe shrinking process is completed;

[0054] 2) after the completion of the first pipe shrinking process, the automatic feeding mechanism of the pipe shrinking device starts to work under the system control, the pipe blank 14 after the first pipe shrinking process is sent to the jig of the second station, and then the above pipe shrinking process is repeated, the length L1 of the pipe blank 14 is increased to L2, the second pipe shrinking process is completed;

[0055] 3) after the completion of the second pipe shrinking process, the automatic feeding mechanism of the pipe shrinking device starts to work under the system control, the pipe blank 14 after the second pipe shrinking process is sent to the jig of the third station, and then the above pipe shrinking process is repeated, the length L2 of the pipe blank 14 is increased to L3, the third pipe shrinking process is completed, and the pipe blank 14 is sent out by the automatic feeding mechanism, and the pipe shrinking is completed.

[0056] The above has made a detailed description of the present application, the above is only the preferred embodiment of the present application, and cannot limit the scope of the present application, that is, any equivalent change and modification made according to the scope of the present application should still fall within the scope of the present application.

Claims

1. A tube shrinking process using a uniform wall thickness tube shrinking die, characterized in that: The uniform wall thickness tube shrinking die is slidably mounted on the tube shrinking device. The tube shrinking die includes a unary unit and a binary unit. The binary unit is disposed outside the unary unit. The two units are slidably mounted on the tube shrinking device to form a binary structure with a synchronous sliding process and an independent sliding process. The sliding distance of the binary unit is greater than the sliding distance of the unary unit. The excess sliding distance of the binary unit constitutes the binary distance, which is also the maximum distance between the unary unit and the binary unit during the independent sliding process. The unary unit includes a tube shrinking mold core, which is mounted on the front end of a sliding support body to form a structure that can move synchronously with the sliding support body; the sliding support body has a molding cavity, a mold core rod is inserted into the molding cavity, and the tail end of the mold core rod is mounted on the binary unit to form a structure that can move synchronously with the binary unit; the binary unit is connected to a driving mechanism, which drives the binary unit to slide, and the binary unit drives the unary unit to move to complete the tube shrinking molding; The inner cavity of the tube reduction mold core includes a flared section and a straight section, the flared section is located at the front end and faces the tube blank, and the straight section is located at the rear end and butts against the tail of the flared section; the minimum inner diameter of the flared section is larger than the outer diameter of the tube blank, while the inner diameter of the straight section is equivalent to the outer diameter of the tube blank; when the mold core rod is in the mold open state, its head is located in the straight section of the tube reduction mold core, and the minimum distance between the outer surface of the mold core rod head and the inner wall of the straight section of the tube reduction mold core is the same as the wall thickness of the tube blank; when the tube reduction mold is closed, the binary unit and the unary unit fit together, the head of the mold core rod enters the flared section of the tube reduction mold core, and the distance between the head of the mold core rod and the inner wall of the flared section is larger than the wall thickness of the tube blank; The flared section of the tube reduction mold core is a tapered structure that gradually contracts inward. The head of the mold core rod is a thickening head with a diameter larger than the diameter of the main part of the mold core rod. The thickening head is located in the straight section of the tube reduction mold core in the mold open state, and the minimum distance between the outer surface of the thickening head and the inner wall of the straight section of the tube reduction mold core is the same as the wall thickness of the tube blank. When the tube reduction mold is closed, the binary unit and the unary unit are affixed to each other, and the thickening head enters the flared section of the tube reduction mold core, and the distance between the thickening head and the inner wall of the flared section is greater than the wall thickness of the tube blank. The sliding support body is installed on a first support base, and the first support base is installed on the guide rail of the tube shrinking device through a slider; The binary unit includes a second support base, which is mounted on the guide rail via another slider and is located outside the first support base; The binary unit further includes a cooling mechanism, which extends into the molding cavity of the sliding support body and is aligned with the mold core rod and the tube blank inserted into the molding cavity; The second support seat is connected to the side cylinder rod of the side cylinder serving as the driving mechanism through a side cylinder flange, and the linear distance is the maximum distance between the second support seat and the first support seat when they slide relative to each other; Follow these steps: Step 1: Place the tube blank into the fixture of the tube shrinking equipment; Step 2: The tube shrinking equipment clamps the middle shape of the tube blank under the control of the CNC system, and the left and right cylinders push the tube shrinking die under the control of the system to start shrinking the tube blank; Step 3: The side cylinder rod pushes the tube reduction mold toward the tube blank, causing the mold core rod and the tube reduction mold core to also move toward the tube blank. When the tube reduction mold core contacts the tube blank, due to the resistance of the tube blank entering the mold, the binary unit slides backward under the action of the resistance. After the sliding distance reaches the binary distance, it fits with the binary unit. At this time, the thickened head of the mold core rod extends into the flared section of the tube reduction mold core. Since the gap here is larger than the gap in the straight section, the tube blank can smoothly pass through the tube reduction mold core and enter the molding cavity when it is introduced into the tube reduction mold. Step 4: When the tube billet enters the forming cavity, the wall thickness of the tube billet increases and becomes a wavy irregular shape due to the extrusion of the tube shrinkage mold core and the mold core rod; Step 5: After the tube has completely entered the shrinking die to the set length, the binary unit begins to retract under the drive of the side cylinder rod. At this time, the linear unit remains stationary due to the friction with the tube. Under the retraction of the binary unit, it is pulled to the linear distance. At the same time, the thickened end of the mold core rod is pulled back to the straight section of the shrinking die core. This process is called binary action. Step 6: The binary unit continues to retract, driving the unary unit to pull the tube reduction mold back as a whole. Since the gap between the thickened head of the mold mandrel and the inner wall of the straight section of the tube reduction mold core is the same as the original wall thickness of the tube blank, the pulling back of the mold mandrel causes the increased wall thickness of the tube blank to be trimmed back to the original thickness. Step 7: After the shrinking mold is retracted as a whole, the tube blank returns to its original wall thickness and is smooth and flat as a whole, and the tube shrinking is completed.

2. The tube shrinking process according to claim 1, characterized in that: The cooling mechanism includes a water inlet pipe and a cooling pipeline. The water inlet pipe is arranged on the second support seat. The cooling pipeline is connected to the water inlet pipe and extends through the second support seat to the forming cavity. A water nozzle is installed at the outlet of the cooling pipeline through the water channel cover plate, and the water nozzle is aimed at the mold core rod and the tube blank inserted into the forming cavity.

3. The tube shrinking process according to claim 2, characterized in that: When the tube blank enters and exits the tube shrinking mold, the tube shrinking mold and the tube blank are lubricated and cooled through the water nozzle.

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