Method for extruding tube blanks when preparing polytetrafluoroethylene two-color spiral tubes

Abstract

The invention provides a method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube. The method comprises the following steps: two semi-circular ring column cylinder bodies with semi-circular ring column tube blanks of different colors arranged therein are detachably enclosed to form a cylinder, the cylinder is detachably connected to a frame of an extrusion device, and a piston rod is driven to move in the cylinder by an extrusion oil cylinder so as to extrude a two-color circular ring column tube blank composed of two semi-circular ring column tube blanks of different colors out of the cylinder, and the operation is efficient and quick. Specific steps: put the semi-circular column tube blank A into the semi-circular column cylinder body A, put the semi-circular column tube blank B into the semi-circular column cylinder body B, the cylinder body A and the cylinder body B are connected and surrounded to form a circular column cylinder, the semi-circular column tube blank A and the semi-circular column tube blank B form a circular column tube blank, and the core rod in the extrusion device passes through the center of the circular column tube blank; the cylinder body A and the cylinder body B are detachably connected together; the cylinder is detachably connected to the frame; a piston matching the cylinder is slidably set on the core rod; the piston moves along the core rod in the cylinder to extrude the tube blank from the cylinder.

Description

Technical Field

[0001] The invention relates to a method for extruding a tube blank, and more specifically to a method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube. Background Art

[0002] Polytetrafluoroethylene (PTFE) is a high-performance thermoplastic (also known as F4). It is widely used in medical heat shrink tubing because of its high temperature resistance, chemical solvent resistance, stable chemical properties, biocompatibility, non-stickiness, wide long-term use temperature range, and self-cleaning properties.

[0003] In recent years, unlike traditional internal medicine and surgery, doctors in the interventional department use CT, MRI, ultrasound and other medical imaging equipment to guide them, and use specific instruments such as catheters and guidewires to reach the lesion site for diagnosis and treatment. They have the advantages of small incision, high accuracy and wide indications, and have been widely used. As a modern medical device, the endoscope is introduced into various natural cavities and minimally invasive interventions, and the endoscopic image is obtained by connecting imaging equipment or directly observing with the naked eye. Endoscopes are mainly used in the fields of digestive system, urinary system or respiratory system, gynecology, etc. In interventional medicine, the visible time and range are subject to certain restrictions, and it is difficult for the attending physician to accurately locate and quickly navigate the internal tissue through the cavity or other reference objects. To solve this problem, researchers and production workers have made many improvements to medical catheters, such as considering adding a coating directly to the medical catheter, but this method is difficult to achieve long-term non-fading of the coating and continuous good coloring power.

[0004] If the surface of a medical catheter has spiral stripes of two colors alternating with a certain pitch (i.e., a two-color spiral tube), it can be used in conjunction with an endoscope or other equipment to facilitate doctors to accurately locate and navigate internal tissues.

[0005] In the prior art, polytetrafluoroethylene tubes are generally formed by extrusion molding first and then sintering and other treatments. In the extrusion device, the cylinder is fixed on the frame of the extrusion device, and the extrusion port at the lower end of the cylinder is connected to the die cavity of the extrusion die. The core rod (for example, the lower end of the core rod is fixed on the extrusion die) that cannot move relative to the cylinder extends upward through the cylinder and passes through the piston and the piston rod. The lower end of the piston rod is fixedly connected to the piston, and the upper end extends into the extrusion cylinder. The extrusion cylinder moves, driving the piston rod to move up and down, and the piston can move in and out of the cylinder along the core rod.

[0006] During operation, the extrusion cylinder first drives the piston rod and piston to move upward, and the piston comes out from the upper port of the cylinder. Then, the mixture containing polytetrafluoroethylene is added into the cylinder from the upper port of the cylinder. Then, the extrusion cylinder first drives the piston rod and piston to move downward, and the piston enters the cylinder and moves downward along the core rod to extrude the mixture. The mixture is extruded from the lower port of the cylinder into the extrusion die cavity, and is formed into a prefabricated tube after passing through the extrusion die cavity. The cylinder used in the pre-pressing process is mostly a single-cavity cylinder, which cannot be disassembled. Only one color of tube blank can be pressed out in this cylinder. Single-color blanks can only produce polytetrafluoroethylene pipes of one color, which has certain limitations.

[0007] To prepare a polytetrafluoroethylene two-color spiral tube, the prerequisite is to form a two-color tube blank in the cylinder, then extrude the two-color tube blank to obtain a two-color prefabricated tube, and then perform other subsequent processes to obtain a two-color spiral tube. It is obviously impossible to prepare a two-color tube blank or extrude a two-color prefabricated tube using the existing polytetrafluoroethylene tube extrusion device and method. Summary of the invention

[0008] The invention provides a method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube. The method comprises the following steps: two semi-circular ring column cylinder bodies with semi-circular ring column tube blanks of different colors arranged inside are detachably enclosed to form a cylinder, the cylinder is detachably connected to a frame of an extrusion device, and a piston rod is driven to move in the cylinder by an extrusion oil cylinder, so that a two-color circular ring column tube blank composed of two semi-circular ring column tube blanks of different colors can be extruded out of the cylinder, and the operation is efficient and quick.

[0009] The method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube of the present invention comprises the following steps:

[0010] 1) placing a semi-circular column tube blank A into a semi-circular column cylinder body A, placing a semi-circular column tube blank B into a semi-circular column cylinder body B, the semi-circular column tube blank A and the semi-circular column tube blank B have different colors, both of which are semi-circular column tube blanks that are not loose and are obtained by applying a certain pressure to a mixture containing polytetrafluoroethylene and color paste, and the semi-circular column cylinder body A and the semi-circular column cylinder body B are both semi-circular column cylinder bodies; the cylinder body A and the cylinder body B are butted and surrounded, the cylinder body A and the cylinder body B form a circular column cylinder, the semi-circular column tube blank A and the semi-circular column tube blank B form a circular column tube blank, and the cylinder body A and the cylinder body B are connected together by a detachable connecting mechanism; when butted and surrounded, the core rod in the extrusion device passes through the center of the circular column tube blank; the cylinder is detachably connected to the frame of the extrusion device; the piston in the extrusion device is slidably set on the core rod, and the piston matches the cylinder;

[0011] 2) The extrusion device moves, the piston moves along the core rod in the cylinder, and the tube is extruded from the cylinder.

[0012] In the above method for preparing a polytetrafluoroethylene two-color spiral tube by extruding a tube blank,

[0013] Preparation of semicircular ring column tube blank A: assemble a cylinder body A and a partition together, the side plane of the cylinder body A fits with the inner surface of the partition, arc flanges extending parallel to the axis of the cylinder body are arranged on both sides of the partition, the arc flanges fit with the arc surface of the cylinder body, a semi-cylinder coaxial with the cylinder body is arranged on the inner surface of the partition, a plugging plate is arranged at one end of the axis direction of the cylinder body and the partition, used for blocking one end of the internal space surrounded by the inner surface of the cylinder body, the inner surface of the partition, and the outer arc surface of the semi-cylinder; add a mixture A containing polytetrafluoroethylene and color paste A into the internal space; use an auxiliary tool to apply a certain pressure to the mixture so that the mixture A in the internal space is shaped to form a semicircular ring column tube blank A, remove the partition and the plugging plate, and the semicircular ring column tube blank A is not loose;

[0014] Using a method similar to the above, a mixture B containing polytetrafluoroethylene and color paste B is added into the inner surface of the cylinder body B, the inner surface of another partition, and the inner space surrounded by the outer arc surface of the semi-cylinder to prepare a semi-circular ring column tube blank B:

[0015] The cylinder body A containing the semicircular ring column tube blank A is butted and surrounded with the cylinder body containing the semicircular ring column tube blank B.

[0016] In the above method for preparing a polytetrafluoroethylene two-color spiral tube by extruding a tube blank,

[0017] A slot A is formed on the outer surface of the cylinder body A, a slot B is formed on the outer surface of the cylinder body B, the transition connection half ring A has a snap-fit ​​portion A extending into the slot A, and the transition connection half ring B has a snap-fit ​​portion B extending into the slot B; the transition connection half ring A and the transition connection half ring B are connected in a detachable manner, and the transition connection half ring A and the transition connection half ring B have through holes for passing screws;

[0018] The clamping part A on the transition connection half ring A is extended into the clamping groove A, and the clamping part B on the transition connection half ring B is extended into the clamping groove B. The transition connection half ring A and the transition connection half ring B are connected in a detachable manner. The transition connection half ring A and the transition connection half ring B are connected to the frame of the extrusion device with transition connection screws.

[0019] In the above method for preparing a polytetrafluoroethylene two-color spiral tube by extruding a tube blank,

[0020] A semi-annular groove A is formed on the outer surface of the cylinder body A, and a semi-annular groove B is formed on the outer surface of the cylinder body B. When the cylinder body A and the cylinder body B are butted together to form a cylinder, the semi-annular groove A and the semi-annular groove B form an annular groove on the cylinder; it also includes a stopper sleeve, which is detachably connected to the cylinder and is used to prevent the stopper from coming out of the extrusion port of the cylinder; the stopper sleeve includes a front end plate, a rear stopper ring, and an intermediate body connecting the front end plate and the rear stopper ring; the front end plate, the rear stopper ring, and the intermediate body are all provided with openings extending in the radial direction of the stopper sleeve, the opening width on the front end plate is consistent with the outer diameter of the core rod, the opening width on the rear stopper ring is consistent with the outer diameter of the annular groove, and the opening width on the intermediate body is not less than the outer diameter of the cylinder;

[0021] After step 1) and before step 2), there is step 1"): inserting two semi-circular annular column blocks into the extrusion port of the cylinder away from the piston, the two semi-circular annular column blocks surround the core rod to form an annular column block; inserting the stopper sleeve into the cylinder along the radial direction, the front end plate is located at the end face of the extrusion end of the cylinder, and the rear stopper ring extends into the annular groove on the cylinder; the extrusion device is activated, the piston moves along the core rod in the cylinder, and the tube blank is squeezed toward the block direction to obtain a further compacted tube blank; then the stopper sleeve is removed from the cylinder, and the block is taken out.

[0022] In the above method for preparing a polytetrafluoroethylene two-color spiral tube by extruding a tube blank, the cylinder body A and the cylinder body B are threadedly connected by passing through a screw hole on one cylinder body and a screw hole on the other cylinder body. The diameter of the cylinder is 30-120 mm and can be adjusted as needed.

[0023] In the above method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube, each cylinder body is provided with 6 screw holes which are staggeredly distributed.

[0024] In the above-mentioned method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube, the transition connection half ring is provided with two screw holes.

[0025] In the above method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube, the cylinder body is made of stainless steel.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. In the traditional extrusion device, the core rod passes through the integral cylinder, and the cylinder cannot be disassembled, so it is impossible to extrude the two-color polytetrafluoroethylene tube. The present invention adopts two semi-circular ring column cylinder bodies butted to form a circular ring column cylinder, and two semi-circular ring column tube blanks butted to form a circular ring column tube blank. The existence of the core rod will not affect the butt joint of the two cylinder bodies and the butt joint of the two semi-circular ring column tube blanks.

[0028] 2. It is more convenient to prepare semi-circular ring column tube blanks by using a preparation device composed of a cylinder body, a partition, a plugging plate, etc. Flanges that can fit with the arc surface of the cylinder body are arranged on both sides of the partition, and there is a raised semi-cylindrical structure in the middle of the partition. The flanging can ensure that the partition will not be separated from the cylinder body when the mixture is pre-pressed, and the flanging will not affect the axial movement of the partition relative to the cylinder body, so it is convenient to remove the partition. As a semi-circular plate, the plugging plate has a simple structure and is more convenient to use. The use of a pressing block is convenient for pre-pressing the mixture.

[0029] The semi-circular ring column tube blank can be prepared by using the preparation device. The semi-circular ring column tube blank is taken out from the preparation device, and two semi-circular ring column tube blanks of different colors are surrounded and butted together to obtain a two-color tube blank.

[0030] 3. When two preparation devices are used, it is only necessary to separate the partition plate, blocking plate, etc. from the cylinder body, and there is no need to separate the semi-circular ring column tube blank from the cylinder body. The two cylinder bodies are butt-jointed into one cylinder, and at the same time, the two semi-circular ring column tube blanks are butt-jointed into a two-color circular ring column tube blank. The cylinder is connected to the frame in a detachable manner, and the extrusion cylinder can be used to extrude the two-color tube blank, which greatly improves the operating efficiency.

[0031] 4. The transition connection ring is formed by the transition connection half ring A and the transition connection half ring B, and the transition connection ring is detachably connected to the frame, which further improves the efficiency of connecting the cylinder to the frame. The transition connection half ring A is connected to the transition connection half ring B, which also prevents the two cylinder bodies from separating.

[0032] 5. This extrusion method can also pre-press out a two-color tube blank with uniform color, and the junction of the two-color tube blank is basically parallel to the axis of the tube blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 , 2 They are three-dimensional diagrams of the cylinder body;

[0034] Figure 3 , 4 Separate three-dimensional diagram of the partition;

[0035] Figure 5 It is a schematic diagram of the assembly of the partition plate, cylinder body, pressure block, etc.;

[0036] Figure 6 for Figure 5 DD cross-sectional view;

[0037] Figure 7 for Figure 5 EE cross-sectional view;

[0038] Figure 8 , 9They are three-dimensional diagrams of the cylinder body connected to the extrusion device;

[0039] Fig.10 It is a front view of the cylinder body and the like of Example 1 connected to the extrusion device;

[0040] Fig.11 for Fig.10 AA section view;

[0041] Fig.12 for Fig.10 Left view of;

[0042] Fig.13 for Fig.10 CC section view;

[0043] Fig.14 , 15 They are three-dimensional diagrams of the cylinder body and the like of Example 2 connected to the extrusion device;

[0044] Fig.16 , 17 18 are three-dimensional diagrams of the retaining sleeve.

[0045] Description of reference numerals:

[0046] Cylinder body 1, partition 2, flange 21, semi-cylinder 22, plug 3, pressure block 4, transition connection half ring 5, screw 6 Cylinder body A11, cylinder body B12, cylinder 13, side plane 14, screw hole 15, screw hole 16

[0047] Transition connection half ring A51, transition connection half ring B52, transition connection ring 53, clamping part A55, clamping part B56, transition connection screw 59

[0048] Slot A71, slot B72, semi-circular ring column tube blank A81, semi-circular ring column tube blank B82

[0049] Block sleeve 9, intermediate body 92, front end plate 91, rear block ring 93, semi-ring groove A95, semi-ring groove B96, ring groove 97, annular column block 99,

[0050] Extrusion device 100, core rod 200, piston 300, frame 400, cylinder 500 DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0052] Embodiment 1:

[0053] Reference Figure 5-8The preparation device of the polytetrafluoroethylene two-color spiral tube blank includes a cylinder body 1, a partition plate 2, a plugging plate 3, a pressing block 4, a transition connection half ring 5, a screw 6, etc. The cylinder body 1, the partition plate 2, the plugging plate 3, the pressing block 4, and the transition connection half ring 5 are all two, and the structure is basically the same.

[0054] The two cylinder bodies 1 are cylinder body A11 and cylinder body B12, and the two transition connection half rings 5 ​​are transition connection half ring A51 and transition connection half ring B52.

[0055] See also Figure 1-4 The cylinder body 1 is a semi-circular column, and the side plane 14 of the semi-circular column cylinder body is in contact with the inner surface of the partition 2. Arc flanges 21 extending parallel to the axis of the cylinder body are arranged on both sides of the partition. The arc flanges 21 are in contact with part of the arc surface of the cylinder body. A semi-cylinder 22 coaxial with the cylinder body is provided on the inner surface of the partition. A blocking plate 3 is arranged at one end in the axial direction of the cylinder body and the partition. The blocking plate 3 is a semi-circular plate in contact with the end face of the cylinder body, the end face of the semi-cylinder and the end face of the partition. The blocking plate 3 is fixed at one end of the partition 2, and is used to block one end port of the internal space surrounded by the inner surface of the cylinder body, the inner surface of the partition and the outer arc surface of the semi-cylinder.

[0056] A pressure block 4 is provided at the other end of the axial direction of the cylinder body and the partition, and is used to block the other end port of the internal space. The pressure block 4 can move along the axial direction of the cylinder body under the action of external force to compress the mixture including polytetrafluoroethylene in the internal space.

[0057] When the side plane of the cylinder body A11 fits with the side plane of the cylinder body B12, they can form an annular column cylinder 13.

[0058] A plurality of countersunk screw holes 15 and a plurality of through screw holes 16 are provided on the side planes 14 of the two cylinder bodies. The screw holes 15 on one cylinder body are opposite to the screw holes 16 on the other cylinder body. The screws 6 pass through the screw holes on one cylinder body and are threadedly connected to the screw holes on the other cylinder body, thereby detachably connecting the two cylinder bodies that constitute the cylinder.

[0059] A slot A71 is formed on the outer surface of one end of the cylinder body A11, a slot B72 is formed on the outer surface of one end of the cylinder body B, a snap-in portion A55 extending into the slot A is formed on the transition connection half ring A51, and a snap-in portion B56 extending into the slot B is formed on the transition connection half ring B52. The detachable connection method between the transition connection half ring A and the transition connection half ring B is similar to that between the two cylinder bodies, and will not be described in detail.

[0060] A semi-annular groove A95 is formed on the outer surface of the other end of the cylinder body A, and a semi-annular groove B96 is formed on the outer surface of the other end of the cylinder body B. When the cylinder body A and the cylinder body B are butted together to form a cylinder, the semi-annular groove A and the semi-annular groove B form an annular groove 97 on the cylinder.

[0061] The transition connection half ring A and the transition connection half ring B are provided with through holes through which screws pass.

[0062] The method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube comprises the following steps:

[0063] See also Figure 5-7 and Fig.13 , prepare the semi-circular ring column tube blank A81: insert the cylinder body A11 into the partition 2 along the axial direction until the plugging plate 3 blocks the port at one end of the internal space surrounded by the inner surface of the cylinder body A, the inner surface of the partition, and the outer arc surface of the semi-circular cylinder. Add the mixture A containing polytetrafluoroethylene and color paste A into the internal space; use auxiliary tools or pressing blocks to apply a certain pressure to the mixture so that the mixture A in the internal space is shaped into a semi-circular ring column tube blank A81, and remove the auxiliary tools or pressing blocks. Pull the partition along the axis to separate the partition from the cylinder body A11, and obtain the cylinder body A11 containing the semi-circular ring column tube blank A81 inside.

[0064] Using a method similar to the above, a mixture B containing polytetrafluoroethylene and color paste B is added to the inner surface of the cylinder body B, the inner surface of another partition, and the internal space surrounded by the outer arc surface of the semi-cylinder to prepare a cylinder body B12 containing a semi-circular ring column tube blank B82 inside.

[0065] See also Figure 8-13 The cylinder body A containing the semicircular ring column tube blank A and the cylinder body B containing the semicircular ring column tube blank B are butted together, the cylinder body A and the cylinder body B are butted together to form a cylinder, and the semicircular ring column tube blank A and the semicircular ring column tube blank B are butted together to form a circular ring column double-color tube blank. When butted together, the core rod 200 in the extrusion device 100 passes through the center of the circular ring column tube blank. The cylinder body A and the cylinder body B are connected together by screws 6.

[0066] The clamping part A55 on the transition connection half ring A51 extends into the clamping groove A71, and the clamping part B56 on the transition connection half ring B52 extends into the clamping groove B72. The transition connection half ring A is connected to the transition connection half ring B by a screw 6. The transition connection half ring A and the transition connection half ring B are connected to the frame 400 of the extrusion device by a transition connection screw 59 passing through a through hole. The piston 300 in the extrusion device is slidably arranged on the core rod 200, and the piston matches the cylinder.

[0067] The oil cylinder 500 in the extrusion device is activated, and the piston 400 moves along the core rod in the cylinder barrel 13 to extrude the two-color tube blank from the cylinder barrel.

[0068] The diameter (inner diameter) of the cylinder is 30 mm, the thickness of the partition 2 is 1.5 m; each cylinder body is provided with 6 screw holes, which are staggered and distributed. The cylinder body is made of stainless steel.

[0069] Embodiment 2:

[0070] The main difference between Example 2 and Example 1 is: Figure 14-15 Embodiment 2 further comprises a circular column stopper 99 formed by two semicircular column stoppers enclosing and butting together, and a stopper sleeve 9 detachably connected to the cylinder barrel. Figure 16-18 The retaining sleeve 9 includes a front end plate 91, a rear retaining ring 93, and an intermediate body 92 connecting the front end plate and the rear retaining ring; the front end plate, the rear retaining ring, and the intermediate body are all provided with openings extending in the radial direction of the retaining sleeve, the opening width on the front end plate 91 is consistent with the outer diameter of the core rod 200, the opening width on the rear retaining ring 93 is consistent with the outer diameter of the annular groove 97, and the opening width on the intermediate body 92 is consistent with the outer diameter of the cylinder.

[0071] When in use, first clean the two partitions 2 and the briquette 4, disassemble the cylinder in the assembled state, assemble the partition 2 and the main body of the oil cylinder in turn, add the A color mixture, install the briquette, and then use auxiliary tools to apply a certain amount of pressure to shape the internal mixture, remove the partitions and briquette materials so that they are not loose, and obtain the barrel body with semi-compacted materials. Then, according to the same method as above, obtain the barrel body with semi-compacted materials of another color. The cylinder bodies respectively loaded with semi-compacted materials of two colors are fixedly connected with screws, and the transition connection half ring 5 is fixedly connected to the frame with two screws, and the screw is installed in the middle.

[0072] See also Figure 14-15 ,refer to Figure 8-13 , two semi-circular annular column blocks are inserted into the extrusion port of the cylinder 13 away from the piston, and the two semi-circular annular column blocks surround the core rod 200 to form an annular column block 99; the stopper sleeve 9 is inserted into the cylinder 13 along the radial direction, the front end plate 91 is located at the end face of the extrusion end of the cylinder, and the rear stopper ring 93 extends into the ring groove 97 on the cylinder; start the hydraulic cylinder, the piston moves along the core rod in the cylinder, and squeezes the tube blank toward the block direction to obtain a further compacted tube blank; the two-color tube blank has uniform color, and the junction of the two colors is basically parallel to the axis, which provides a basis for the later preparation of a two-color spiral heat shrink tube with uniform color. Then remove the stopper sleeve 9 from the cylinder 13 and remove the block.

[0073] The extrusion die is connected to the extrusion end of the cylinder, the hydraulic cylinder is started, the piston moves along the core rod in the cylinder, and the tube blank is extruded from the cylinder into the extrusion die cavity to carry out the subsequent polytetrafluoroethylene two-color spiral tube preparation process.

[0074] The above-mentioned embodiments only express several implementation methods of the present application, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, any number of variations and improvements, without departing from the concept of the present application, belong to the protection scope of the present application.

Claims

1. A method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube, characterized in that: The following steps are involved: 1) Place a semi-circular column tube blank A into a semi-circular column cylinder body A, and place a semi-circular column tube blank B into a semi-circular column cylinder body B. The semi-circular column tube blank A and the semi-circular column tube blank B have different colors. Both are semi-circular column tube blanks that are not loose and are obtained by applying a certain pressure to a mixture containing polytetrafluoroethylene and color paste. The semi-circular column cylinder body A and the semi-circular column cylinder body B are both semi-circular column cylinder bodies; the cylinder body A and the cylinder body B are butted and surrounded, the cylinder body A and the cylinder body B form a circular column cylinder, the semi-circular column tube blank A and the semi-circular column tube blank B form a circular column tube blank, and the cylinder body A and the cylinder body B are connected together by a detachable connection mechanism; when butted and surrounded, the core rod in the extrusion device passes through the center of the circular column tube blank; the cylinder is detachably connected to the frame of the extrusion device; the piston in the extrusion device is slidably set on the core rod, and the piston matches the cylinder; 2) The extrusion device starts to work, and the piston moves along the core rod in the cylinder to extrude the tube from the cylinder.

2. The method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube as claimed in claim 1, characterized in that: Preparation of semi-circular annular column tube blank A: assemble a cylinder body A and a partition together, the side plane of the cylinder body A fits with the inner surface of the partition, arc-shaped flanges extending parallel to the axis of the cylinder body are arranged on both sides of the partition, the arc-shaped flanges fit with the arc surface of the cylinder body, and a semi-cylinder coaxial with the cylinder body is provided on the inner surface of the partition, and a plugging plate is arranged at one end of the axial direction of the cylinder body and the partition to block one end of the internal space surrounded by the inner surface of the cylinder body, the inner surface of the partition, and the outer arc surface of the semi-circular cylinder; add a mixture A containing polytetrafluoroethylene and color paste A into the internal space; use an auxiliary tool to apply a certain pressure to the mixture so that the mixture A in the internal space is shaped to form a semi-circular annular column tube blank A, remove the partition and the plugging plate, and the semi-circular annular column tube blank A is not loose; The preparation method of the semi-circular ring column tube blank A is adopted, and the mixture B containing polytetrafluoroethylene and color paste B is added into the inner surface of the cylinder body B, the inner surface of another partition, and the inner space surrounded by the outer arc surface of the semi-circular cylinder to prepare the semi-circular ring column tube blank B: The cylinder body A containing the semicircular ring column tube blank A is butted and surrounded with the cylinder body containing the semicircular ring column tube blank B.

3. The method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube as claimed in claim 1, characterized in that: A slot A is formed on the outer surface of the cylinder body A, a slot B is formed on the outer surface of the cylinder body B, the transition connection half ring A has a snap-fit ​​portion A extending into the slot A, and the transition connection half ring B has a snap-fit ​​portion B extending into the slot B; the transition connection half ring A and the transition connection half ring B are connected in a detachable manner, and the transition connection half ring A and the transition connection half ring B have through holes for passing screws; The clamping part A on the transition connection half ring A is extended into the clamping groove A, and the clamping part B on the transition connection half ring B is extended into the clamping groove B. The transition connection half ring A and the transition connection half ring B are connected in a detachable manner. The transition connection half ring A and the transition connection half ring B are connected to the frame of the extrusion device with transition connection screws.

4. The method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube as claimed in claim 1, characterized in that: A semi-annular groove A is formed on the outer surface of the cylinder body A, and a semi-annular groove B is formed on the outer surface of the cylinder body B. When the cylinder body A and the cylinder body B are butted together to form a cylinder, the semi-annular groove A and the semi-annular groove B form an annular groove on the cylinder; it also includes a stopper sleeve, which is detachably connected to the cylinder and is used to prevent the stopper from coming out of the extrusion port of the cylinder; the stopper sleeve includes a front end plate, a rear stopper ring, and an intermediate body connecting the front end plate and the rear stopper ring; the front end plate, the rear stopper ring, and the intermediate body are all provided with openings extending in the radial direction of the stopper sleeve, the opening width on the front end plate is consistent with the outer diameter of the core rod, the opening width on the rear stopper ring is consistent with the outer diameter of the annular groove, and the opening width on the intermediate body is not less than the outer diameter of the cylinder; After step 1) and before step 2) there is step 1 " ): Insert two semi-circular annular column blocks into the extrusion port of the cylinder away from the piston, and the two semi-circular annular column blocks surround the core rod to form an annular column block; insert the stopper sleeve into the cylinder along the radial direction, with the front end plate located at the end face of the extrusion end of the cylinder, and the rear stopper ring extending into the annular groove on the cylinder; the extrusion device is activated, and the piston moves along the core rod in the cylinder to squeeze the tube toward the block direction to obtain a further compacted tube; then remove the stopper sleeve from the cylinder and take out the block.

5. The method for extruding a tube blank when preparing a polytetrafluoroethylene two-color spiral tube as claimed in claim 1, characterized in that: The cylinder body A and the cylinder body B are threadedly connected through a screw hole on one cylinder body and a screw hole on the other cylinder body.

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