CN107139440A - Super high molecular weight polymer tubing active matrix driving pulsation deformation forming method and equipment - Google Patents

Abstract

The invention discloses a method and equipment for active-driven pulsation deformation forming of ultra-high molecular weight polymer pipes. The method is to plasticize and extrude ultra-high molecular weight polymer raw materials by using an extruder host, and preform them into sheets. Then the sheet is sent to the pipe forming auxiliary machine for winding and forming into pipe; the equipment includes a connected extruder host and pipe forming auxiliary machine, and the pipe forming auxiliary machine includes a machine barrel and a mandrel arranged in the machine barrel, There are grooves distributed on the inner wall of the barrel; there is a feed port on the side wall at one end of the barrel, the feed port is connected to the main machine of the extruder, the other end of the barrel is the discharge port, and the discharge port is also connected to the die barrel; The mandrel includes a connected shaft body and a shaft head, the shaft body is located in the barrel, and the shaft head is located in the die barrel. The invention uses the grooves on the inner wall of the machine barrel to form a cavity with periodic volume changes between the mandrel and the machine barrel to realize pulsating compression release, promote the diffusion movement of macromolecules, gradually release internal stress, improve welding strength, and improve Productivity.

Description

Actively driven pulsation deformation forming method and equipment for ultra-high molecular weight polymer pipes

technical field

The invention relates to the technical field of extrusion processing of polymer materials, in particular to an active-driven pulsation deformation forming method and equipment for ultra-high molecular weight polymer pipes.

Background technique

Due to its extremely high molecular weight, ultra-high molecular weight polymers make ultra-high molecular weight polymer products have excellent properties that ordinary polymer materials do not have. For example, ultra-high molecular weight polyethylene resin products have high mechanical strength, excellent wear resistance, light weight, environmental protection, and low water absorption, and are widely used in textiles, papermaking, food machinery, transportation, metallurgy, coal and other fields; ultra-high molecular weight PMMA (Polymethyl methacrylate) can maintain mechanical strength at high temperatures above 200°C, and also has strong toughness, wear resistance and impact resistance; while polytetrafluoroethylene, known as the king of plastics, is It has the characteristics of high temperature resistance and extremely low friction coefficient.

However, the critical shear rate of ultra-high molecular weight polymers is low, and melt fracture is prone to occur at very low rotational speeds, resulting in uneven product surfaces, resulting in low production efficiency. The friction coefficient of the material is small, and the feeding section is easy to slip, so that the material cannot be pushed forward along the axis, and the extrusion is likely to be unstable; at the same time, its melt viscosity is high, showing a high elastic state, the degree of diffusion between molecular chains is small, and the relaxation time is long. , prone to weld lines.

There are many traditional UHMW polymer pipe forming processes, including solid-state extrusion, hard top, welding, bonding, winding, etc. Through the hard top method, the obtained pipe has high welding strength, but the extrusion speed is extremely slow; when the extrusion speed is increased, the welding line problem is prominent due to poor welding between different material flows in the pipe die, which is likely to cause internal defects. At the same time, it is difficult to control the quality of the pipe surface. However, the traditional winding pipe is wound in the cooling state of the profile and bonded with hot-melt plastic to form a whole, so the welding strength of the splicing part of the winding pipe is low. Formed by welding and bonding methods, the strength of the weld is less than 50% of the original, which is easy to cause fracture and leakage, so it cannot meet the industrial requirements.

It can be seen that, aiming at the problems existing in the current ultra-high molecular weight polymer pipe forming, it is necessary to develop a method and equipment for forming ultra-high molecular weight polymer pipes with high production efficiency, low internal stress, high welding strength of different material flows, and no weld marks. , which is of great significance to the further development and utilization of many excellent properties of ultra-high molecular weight polymer materials.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an active-driven pulsation deformation forming method for ultra-high molecular weight polymer pipes. This method can effectively improve the pipe forming efficiency under the premise of ensuring high welding strength. Productivity.

Another object of the present invention is to provide an active-driven pulsation deformation forming device for ultra-high molecular weight polymer pipes for realizing the above method.

The technical solution of the present invention is: an active-driven pulsation deformation forming method for ultra-high molecular weight polymer pipes. Send the sheet into the pipe forming auxiliary machine and wind it into a pipe;

The pipe forming auxiliary machine includes a barrel and a mandrel inside the barrel. There are grooves distributed on the inner wall of the barrel. A cavity with periodic pulsating volume is formed between the mandrels, and the melt formed after the sheet is wound is compressed and expanded by the pulsating changes during the transport process in the cavity, which promotes the diffusion and welding of polymer macromolecular chains And the release of internal stress, so as to ensure the welding strength between different material flows of the pipe after forming, and avoid welding marks.

When the sheet enters the pipe forming auxiliary machine, an angle α is formed between the centerline of the sheet and the centerline of the feeding port of the cylinder, and In the formula, D _b is the diameter of the barrel, and W is the width of the sheet. The setting of the included angle enables the sheets to be wound on the mandrel of the pipe forming auxiliary machine and seamlessly spliced.

During the process of conveying the melt formed after the sheet is melted in the cavity, a first heater is provided on the outer circumference of the machine barrel, and the external heating of the first heater is assisted to further promote the diffusion of polymer macromolecular chains, Welding and internal stress relief. In addition, after the pipe is formed and sent out of the pipe forming auxiliary machine, the cooling mechanism and cutting mechanism can be used to cool, shape and cut the pipe in turn, and finally obtain standard pipe products.

The present invention is an active-driven pulsating deformation forming equipment for ultra-high molecular weight polymer pipes, which includes a connected extruder main machine and pipe forming auxiliary machines, and the pipe forming auxiliary machines include machine barrels and mandrels arranged in the machine barrels , the inner wall of the barrel is distributed with grooves; the side wall at one end of the barrel is provided with a feed port, the feed port is connected to the extruder host, the other end of the barrel is the discharge port, and the discharge port is also connected to the die barrel ; The mandrel includes a connected shaft body and a shaft head, the shaft body is located in the barrel, and the shaft head is located in the die barrel. Among them, the feed port is a rectangular through hole opened on the side wall of the barrel, and the sheet formed by the extruder host directly enters the pipe forming auxiliary machine through the feed port; each groove on the inner wall of the barrel (the groove The structure can be an axial groove or a spiral groove) and is evenly distributed on the inner wall of the barrel along the circumferential direction of the barrel; the mandrel is an actively driven rotating mandrel, which can provide driving force, so that the mandrel rotates to drive the material forward, ensuring The molding flow resistance is reduced under the long residence time molding condition, which avoids the problems of high energy consumption and excessive axial pressure due to the large length of the die head.

The shaft head includes a connected transition section and a straight section, both ends of the transition section are respectively connected to the shaft body and the straight section, and the diameter of the transition section gradually decreases along the extrusion direction. That is to say, on the mandrel, the diameter of the straight section is smaller than the diameter of the shaft body, and a transition connection is made between the two through a transition section. The shaft head is made of wear-resistant materials or subjected to surface heat treatment, coating and infiltration to improve wear resistance and alleviate the problem of product size deviation caused by serious surface wear due to friction between the mandrel and the material.

The shape of the inner wall of the die barrel is the same as that of the shaft head. A wear-resistant bushing is also provided between the die barrel and the shaft head. The outer wall of the wear-resistant bush is in contact with the inner wall of the die barrel. The shape of the wear-resistant bush is Also the same as the shaft head. The wear-resistant bushing has an inlet and an outlet connected to the machine barrel. The inlet of the bushing communicates with the discharge port of the machine barrel. A molding cavity is formed between the wear-resistant bushing and the shaft head. The molding cavity is along the direction from the inlet to the outlet. Corresponding gradient sections and straight sections are arranged in turn to realize stable extrusion of pipes and adjustment of product size.

As a preferred solution, on the outer cylindrical surface of the shaft body, an end corresponding to the feed inlet on the barrel is provided with a bevel. In addition, other parts on the mandrel are the optical axis. The structure of the shaft is relatively complicated, but after the sheet enters the feeding port, the beveled edge can produce a bite effect on the sheet, and the bite of the sheet on the beveled edge It is wound on the mandrel at a certain angle, and the volume pulsating cavity is formed between the mandrel and the barrel. The melt is compressed and expanded by pulsating changes, and the diffusion of macromolecular chains is promoted under the auxiliary effect of external heating. And relaxation and internal stress release, effectively eliminate weld marks.

As another preferred solution, the shaft body is an optical shaft. That is, the outer cylindrical surface of the shaft body is a smooth surface without any beveled edges or curved surfaces. The shaft body is simple in structure, easy to process, strong in adaptability, and has no shearing effect on the material, but the bite effect on the sheet is not as good as that of the shaft body with beveled edges.

An included angle α is formed between the extruder main machine and the pipe forming auxiliary machine, and In the formula, D _b is the diameter of the barrel, and W is the width of the sheet. Among them, the angle formed between the main machine of the extruder and the auxiliary pipe forming machine is the angle formed between the centerline of the sheet and the centerline of the feeding port of the barrel. The setting of the angle enables the sheet to be formed in the pipe It is wound on the mandrel of the auxiliary machine and spliced seamlessly.

The outer periphery of the barrel is provided with a first heater, and the outer periphery of the die cylinder is provided with a second heater. In addition, there is a first temperature sensor on the barrel, and a second temperature sensor on the die barrel. The melt in the barrel and the die barrel can be detected in real time through the first temperature sensor and the second temperature sensor. The temperature, which is fed back to the controller of the equipment, can adjust the heating temperature of the first heater and the second heater in real time to keep the melt temperature at a constant temperature.

In addition to the above structure, the pipe forming auxiliary machine also includes a cooling mechanism, a cutting mechanism, an idler supporting mechanism and a driving mechanism. Wherein, the cooling mechanism includes a sizing sleeve and a water tank, and the outlet of the die barrel is sequentially connected with the sizing sleeve and the water tank. The idler support mechanism includes an idler and an idler support frame, the idler is arranged under the pipe at the outlet of the sizing sleeve, and the idler support frame is used to place the idler. Along the extrusion direction, the cutting mechanism is set behind the support mechanism of the idler, which automatically cuts the pipe, realizes the assembly line operation, and has high efficiency, and obtains neat, clean and fixed-length pipes. The driving mechanism includes a motor and a shaft coupling. The motor is connected to the mandrel through the coupling to drive the mandrel to rotate.

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

In the ultra-high molecular weight polymer pipe active-driven pulsation deformation forming method and equipment, the sheet is first extruded through the main extruder, and then the sheet is supplied to the auxiliary pipe forming machine, which can reduce the pressure on the main extruder. Back pressure reduces the size of the extruder host drive mechanism and can effectively improve production efficiency.

In the ultra-high molecular weight polymer pipe active-driven pulsation deformation forming method and equipment, the sheet is wound on a pipe forming auxiliary machine at a certain angle and extruded into a pipe, passing through the groove set on the inner wall of the barrel, A cavity with periodic volume changes is formed between the mandrel and the barrel to realize pulsating compression release, and through the auxiliary effect of external heating, the diffusion movement of macromolecules is promoted, and the internal stress is gradually released, which solves the problems caused by the traditional pipe winding molding method. The problem of low welding strength.

In the ultra-high molecular weight polymer pipe active-driven pulsation deformation forming method and equipment, the mandrel in the pipe forming auxiliary machine is actively driven, which can ensure the reduction of forming flow resistance under the long residence time forming condition, and avoid The problem is that the length of the head is large, the energy consumption is high, and the required axial pressure is large.

Description of drawings

Fig. 1 is a structural schematic diagram of the active-driven pulsation deformation forming equipment for ultra-high molecular weight polymer pipes.

Fig. 2 is a schematic structural diagram of the pipe forming auxiliary machine in Fig. 1 .

Fig. 3 is a front view of the pipe forming auxiliary machine (with a partial cross-sectional schematic diagram in the figure).

Fig. 4 is a top view of the pipe forming auxiliary machine (with a partial cross-sectional schematic diagram in the figure).

Fig. 5 is a schematic structural view of the barrel in Fig. 2 .

Figure 6 is a front view of the barrel (with a partial cross-sectional schematic view among the figures).

FIG. 7 is a cross-sectional view along line A-A of FIG. 6 .

FIG. 8 is a schematic structural view of the mandrel in Embodiment 1.

FIG. 9 is a schematic structural view of the mandrel in Embodiment 2.

detailed description

The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

Example 1

In this embodiment, an active-driven pulsating deformation forming device for ultra-high molecular weight polymer pipes, as shown in Figure 1, includes a connected extruder host 80 (a control box 90 is provided at one end of the extruder host) and a pipe Forming auxiliary machine 70, as shown in Figures 2 to 4, the pipe forming auxiliary machine includes a machine barrel 1 and a mandrel 2 arranged in the machine barrel, as shown in Figures 5 to 7, grooves 1 are distributed on the inner wall of the machine barrel -1; There is a feed port 1-2 on the side wall of one end of the barrel, and the feed port is connected to the main machine of the extruder, and the other end of the barrel is a discharge port 1-3, and the discharge port is also connected to a mold barrel 3 (the end of the die barrel can also be provided with a retaining ring 4); as shown in Figure 3 or Figure 8, the mandrel includes a connected shaft body 2-1 and a shaft head 2-2, and the shaft body is located in the barrel, The shaft head is located in the die barrel. Among them, the feed port is a rectangular through hole opened on the side wall of the barrel, and the sheet formed by the main extruder directly enters the auxiliary pipe forming machine through the feed port; the grooves on the inner wall of the barrel are along the circumference of the barrel. The direction is evenly distributed on the inner wall of the barrel; the mandrel is an actively driven rotating mandrel, which provides the driving force to make the mandrel rotate to drive the material forward, which can ensure the reduction of molding flow resistance under the condition of long residence time molding, and avoid the mold head The problem of large length, high energy consumption, and excessive axial pressure.

As shown in FIG. 8 , the shaft head includes a connected transition section 2-21 and a straight section 2-22. Both ends of the transition section are respectively connected to the shaft body and the straight section. The diameter of the transition section gradually decreases along the extrusion direction. That is to say, on the mandrel, the diameter of the straight section is smaller than the diameter of the shaft body, and a transition connection is made between the two through a transition section. The shaft head is made of wear-resistant materials or subjected to surface heat treatment, coating and infiltration to improve wear resistance and alleviate the problem of product size deviation caused by serious surface wear due to friction between the mandrel and the material.

As shown in Figure 3, the shape of the inner wall of the die barrel is the same as that of the shaft head, and a wear-resistant bushing 5 is also arranged between the die barrel and the shaft head. The outer wall of the wear-resistant bush is in contact with the inner wall of the die barrel. The shape of the grinding bush is also the same as that of the shaft head. The wear-resistant bushing has an inlet and an outlet connected to the machine barrel. The inlet of the bushing is connected to the discharge port of the machine barrel. A molding cavity 6 is formed between the wear-resistant bushing and the shaft head. The molding cavity is along the direction from the inlet to the outlet. Corresponding gradient section and straight section are arranged in turn on the top to realize stable extrusion of pipes and adjustment of product size.

As shown in Fig. 4 or Fig. 8, on the outer cylindrical surface of the shaft body, a bevel 2-11 is provided at the end corresponding to the feed inlet on the machine barrel. In addition, other parts on the mandrel are the optical axis. The structure of the shaft is relatively complicated, but after the sheet enters the feeding port, the beveled edge can produce a bite effect on the sheet, and the bite of the sheet on the beveled edge It is wound on the mandrel at a certain angle, and the volume pulsating cavity is formed between the mandrel and the barrel. The melt is compressed and expanded by pulsating changes, and the diffusion of macromolecular chains is promoted under the auxiliary effect of external heating. And relaxation and internal stress release, effectively eliminate weld lines.

As shown in Figure 1, an angle α is formed between the extruder main machine and the pipe forming auxiliary machine, and In the formula, D _b is the diameter of the barrel, and W is the width of the sheet. Among them, the angle formed between the main machine of the extruder and the auxiliary pipe forming machine is the angle formed between the centerline of the sheet and the centerline of the feeding port of the barrel. The setting of the angle enables the sheet to be formed in the pipe It is wound on the mandrel of the auxiliary machine and spliced seamlessly.

As shown in FIG. 4 , a first heater 7 is provided on the outer periphery of the barrel, and a second heater 8 is arranged on the outer periphery of the die cylinder. In addition, the barrel is also provided with a first temperature sensor 9, and the die barrel is also provided with a second temperature sensor 10, and the temperature in the barrel and the die barrel is detected in real time by the first temperature sensor and the second temperature sensor. The melt temperature is fed back to the controller of the equipment (that is, the above-mentioned complete machine control box 90), and the heating temperature of the first heater and the second heater can be adjusted in real time to keep the melt temperature at a constant temperature. Wherein, the control box 90 is similar to the control box of the existing extruder, through which the controller controls the temperature and speed regulation of the whole equipment, and the controller can adopt PLC to realize automatic control.

In addition to the above structure, the pipe forming auxiliary machine also includes a cooling mechanism, a cutting mechanism, an idler supporting mechanism and a driving mechanism. As shown in FIG. 3 , the cooling mechanism includes a sizing sleeve 11 and a water tank 12 , and the outlet of the die barrel is connected to the sizing sleeve and the water tank in sequence. The idler support mechanism includes an idler 13 and an idler support frame 14, the idler is arranged below the pipe 17 at the outlet of the sizing sleeve, and the idler support is used to place the idler. Along the extrusion direction, a cutting mechanism (not shown in the figure) is set behind the roller support mechanism to automatically cut the pipes to realize assembly line operation with high efficiency and obtain neat, clean and fixed-length pipes. The driving mechanism includes a motor 15 and a shaft coupling 16, the motor is connected with the mandrel through the shaft coupling, and drives the mandrel to rotate. The main extruder used for sheet forming can be an ordinary extruder, or any mechanism that can continuously plasticize and extrude an ultra-high molecular weight polymer sheet, such as a general-purpose extensional rheological extruder in the market.

In this embodiment, a method of active-driven pulsation deformation forming of ultra-high molecular weight polymer pipes can be realized through the above-mentioned equipment. Then the sheet is sent to the pipe forming auxiliary machine to be wound into a pipe;

The pipe forming auxiliary machine includes a barrel and a mandrel installed in the barrel. Grooves are distributed on the inner wall of the barrel. The driving mode of the mandrel adopts active drive (that is, the mandrel of the forming mold is driven by a motor), so that the barrel and the mandrel A cavity with periodic volume fluctuations is formed between the shafts. During the process of transporting the melt in the cavity after the sheet is wound, it is compressed and expanded by the pulsation changes, which promotes the diffusion, welding and bonding of polymer macromolecular chains. The internal stress is released, thereby ensuring the welding strength of the formed pipe and avoiding weld marks.

Wherein, when the sheet enters the pipe forming auxiliary machine, an included angle α is formed between the centerline of the sheet and the centerline of the feeding port of the barrel, and In the formula, D _b is the diameter of the barrel, and W is the width of the sheet. The setting of the included angle enables the sheets to be wound on the mandrel of the pipe forming auxiliary machine and seamlessly spliced.

When the melt formed after the sheet is melted is conveyed in the cavity, a first heater is installed on the outer periphery of the barrel, and the diffusion, welding and bonding of polymer macromolecular chains are further promoted through the external heating of the first heater. Internal stress release. In addition, after the pipe is formed and sent out of the pipe forming auxiliary machine, the cooling mechanism and cutting mechanism can be used to cool, shape and cut the pipe in turn, and finally obtain standard pipe products.

Wherein, the ultra-high molecular weight polymer is a polymer with a molecular weight of more than one million, such as ultra-high molecular weight polyethylene, polytetrafluoroethylene, or ultra-high molecular weight polymethyl methacrylate.

Example 2

This embodiment is an active-driven pulsation deformation forming device for ultra-high molecular weight polymer pipes. Compared with Embodiment 1, the difference lies in that, as shown in FIG. 9 , the axis is the optical axis. That is, the outer cylindrical surface of the shaft body is a smooth surface without any beveled edges or curved surfaces. The shaft body is simple in structure, easy to process, strong in adaptability, and has no shearing effect on the material, but the bite effect on the sheet is not as good as that of the shaft body with beveled edges.

As mentioned above, the present invention can be better realized. The above-mentioned embodiment is only a preferred embodiment of the present invention, and is not used to limit the scope of the present invention; Covered by the scope of protection required by the claims of the present invention.

Claims (10)

1. The deformation forming method 1. super high molecular weight polymer tubing active matrix driving is pulsed, it is characterised in that first with extruder main Super high molecular weight polymer raw material is plastified and extruded by machine, is pre-formed as sheet material, then sheet material is sent into winding in tube forming subsidiary engine It is shaped to tubing；

   Tube forming subsidiary engine includes machine barrel and the mandrel in machine barrel, and machine tube inner wall is distributed fluted, the type of drive of mandrel Using active matrix driving, make what is formed after the cavity for forming the change of volume periodically pulsing between machine barrel and mandrel, sheet material winding to melt During body is conveyed in cavity, by the compression and expansion of pulsatile change, promote polymer macromolecule chain diffusion, Welding and internal stresses release, so as to ensure that the heat seal strength of different streams in forming process.
2. Deformation forming method, its feature 2. super high molecular weight polymer tubing active matrix driving according to claim 1 is pulsed It is, when the sheet material enters tube forming subsidiary engine, angle α is formed between the center line of sheet material and the charging aperture center line of machine barrel, andD in formula_bFor the diameter of machine barrel, W is the width of sheet material.
3. Deformation forming method, its feature 3. super high molecular weight polymer tubing active matrix driving according to claim 1 is pulsed It is, during the melt formed after the sheet material melting is conveyed in cavity, machine barrel periphery is additionally provided with primary heater, leads to The external heat booster action of primary heater is crossed, further promotes diffusion, welding and the internal stresses release of polymer macromolecule chain.
4. The deformation former 4. super high molecular weight polymer tubing active matrix driving is pulsed, it is characterised in that including squeezing for being connected Go out machine host and tube forming subsidiary engine, tube forming subsidiary engine includes machine barrel and the mandrel in machine barrel, and machine tube inner wall is distributed with Groove；The side wall of machine barrel one end is provided with charging aperture, and charging aperture is connected with extruder main frame, and the machine barrel other end is discharging opening, is gone out Material mouth is also associated with mouth mold cylinder；Mandrel includes the axis body and spindle nose being connected, and axis body is located in machine barrel, and spindle nose is located at mouth mold cylinder It is interior.
5. Deformation former, its feature 5. super high molecular weight polymer tubing active matrix driving according to claim 4 is pulsed It is, the spindle nose includes transition and the flat segments being connected, transition two ends are connected with axis body and flat segments respectively, gradual change The diameter of section is gradually reduced along extrusion direction.
6. Deformation former, its feature 6. super high molecular weight polymer tubing active matrix driving according to claim 5 is pulsed It is, the inner wall shape of the mouth mold cylinder is identical with spindle nose, and anti-wearing liner is additionally provided between mouth mold cylinder and spindle nose, anti-wearing liner Outer wall is in contact with the inwall of mouth mold cylinder, and the shape of anti-wearing liner is also identical with spindle nose.
7. Deformation former, its feature 7. super high molecular weight polymer tubing active matrix driving according to claim 4 is pulsed It is, on the external cylindrical surface of the axis body, one end corresponding with the enterprising material mouth of machine barrel is provided with slant edge.
8. Deformation former, its feature 8. super high molecular weight polymer tubing active matrix driving according to claim 4 is pulsed It is, the axis body is optical axis.
9. Deformation former, its feature 9. super high molecular weight polymer tubing active matrix driving according to claim 4 is pulsed It is, angle α is formed between the extruder main frame and tube forming subsidiary engine, andD in formula_bFor machine barrel Diameter, W be sheet material width.
10. Deformation former, its feature 10. super high molecular weight polymer tubing active matrix driving according to claim 4 is pulsed It is, the machine barrel periphery is provided with primary heater, mouth mold cylinder periphery is provided with secondary heater.