CN106976218A - The minor caliber pipe extruding forming method and device of a kind of weldless trace - Google Patents

Abstract

The invention discloses a method and device for extrusion molding of small-diameter pipes without welding lines. The hollow screw of the device is installed in the inner hole of the barrel, one end of which is matched with the hollow transmission sleeve of the reduction box and connected by a flat key, and the other end extends into the supporting cover; the mandrel is concentrically placed in the inner hole of the hollow screw, The inner hole of the hollow screw and the mandrel form a circular gap; the mandrel is installed on the support cover, and the mandrel extends out of the support cover to connect with the mandrel driving device; It is a two-segment cone coaxial with the mandrel. The invention has the advantages of compact structure, high energy utilization rate and improved pipe hoop strength, which is beneficial to reduce the wall thickness of the pipe product under the premise of ensuring the performance of the product, reduces the cost and reduces "white pollution".

Description

A small-diameter pipe extrusion molding method and device without weld lines

technical field

The invention relates to the technical field of advanced molding and processing of polymers and composite materials thereof, in particular to a small-caliber pipe extrusion molding method and device without weld marks, and belongs to the field of polymer material molding processing equipment.

Background technique

Compared with metal pipes and cement pipes, plastic pipes have the advantages of high specific strength, good corrosion resistance, good impact resistance and tensile resistance, and at the same time, due to the smooth inner wall of plastic pipes, small friction coefficient, low flow resistance, convenient transportation, It is widely used in various industries due to its advantages such as simple installation.

Pipe extrusion molding has the advantages of high efficiency, continuous production process, and wide adaptability to materials. It is currently the most commonly used molding method for plastic pipes. During the pipe extrusion molding process, the material is melted and plasticized in the plasticizing system composed of a screw and a barrel, and the product is obtained through a shaping device, a cooling device, a traction device, and a cutting device in sequence. Due to the existence of shunt shuttles and brackets in the commonly used extruder heads at present, when the melt passes through the shunt shuttle or its brackets, multiple melts are produced and then merged. It cannot be completely fused to form defects, and weld marks are generated on the surface of the pipe, which reduces the hoop strength and appearance quality of the pipe product, and greatly limits the application as a plastic pressure pipe.

Scholars and manufacturers at home and abroad have adopted many different methods to reduce the negative impact of weld lines on product performance. The commonly used methods mainly include: ① improving the fluidity of the melt; ② changing the flow form of the melt in the die; ③ optimizing The structural shape and size of the machine head. U.S. Patent US5468808 discloses a method of using different molecular weight polypropylenes together to reduce weld lines, in which low molecular weight polypropylene plays a role in improving melt flow properties, while high molecular weight polypropylene provides necessary mechanical properties; Chinese patent CN 201410497381 By mixing polypropylene with different flow properties, the strength of the weld line is significantly improved, and the performance of the pipe is improved; the Chinese patent CN 200810045785.9 produces a shearing effect on the melt through the relative rotational movement of the inner die and the mandrel, At the same time, the inner and outer walls of the pipe are cooled and shaped separately, and the strength of the weld line is improved while the condensed structure of the product is regulated to improve the performance of the product. Chinese patent CN201110100814.9 divides the melt from the extruder into four melts according to the thickness requirements of the pipe through a splitter, and each melt is transported separately to form staggered weld lines at different positions of the pipe to achieve self-reinforcement of the pipe.

The above method reduces the influence of the weld line on the performance of the product to a certain extent, but the weld line still objectively exists in the product. Once the weld line area is damaged, the entire pipe will be scrapped.

It can be seen that in view of the shortcomings of the current plastic pipe forming methods and equipment, it is of great significance to develop a pipe extrusion molding method and device without weld marks for plastic pipe extrusion molding.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of low circumferential strength and poor surface quality caused by the existence of weld marks in the extrusion molding process of commonly used pipe products at present, and provide a small-diameter plastic pipe extrusion molding method without weld marks, which can improve While improving the product performance, reduce the wall thickness of the pipe, reduce the production cost, prolong the service life of the pipe and reduce "white pollution".

Another object of the present invention is to provide a high-performance pipe extrusion molding device for realizing the above method.

The object of the invention is achieved through the following technical solutions:

A small-diameter pipe extrusion molding device without weld marks, including a frame, a motor, a spray cooling device, a roller traction mechanism, a barrel, a hollow screw, a mandrel, a shunt shuttle and a support cover; both ends of the frame The gear box and mandrel driving device are respectively provided; the motor is connected with the gear box through a coupling; a hollow transmission sleeve is arranged in the gear box; one end of the barrel is installed on one side of the end cover of the gear box, and the spray cooling device and The roller traction mechanism is coaxially installed on the other side of the end cover of the reduction box in turn; a hopper is provided on the material barrel, and the hopper communicates with the inner hole of the material barrel; the inner hole of the material barrel is coaxial with the hollow transmission sleeve of the reduction box; The other end of the cylinder is connected with the support cover; the hollow screw is installed in the inner hole of the material cylinder, one end is matched with the hollow transmission sleeve of the reduction box and connected by a flat key, and the other end extends into the support cover; the mandrel is placed concentrically in the hollow In the inner hole of the screw, the inner hole of the hollow screw and the mandrel form an annular gap; the mandrel is installed on the support cover, and the mandrel extends out of the support cover to connect with the mandrel driving device; the mandrel located in the support cover is processed Out of the shunt shuttle, the shunt shuttle is a two-section cone coaxial with the mandrel.

In order to further realize the object of the present invention, preferably, the mandrel is installed on the support cover through a deep groove ball bearing, and the outer side of the deep groove ball bearing is provided with a gland; the inner side of the deep groove ball bearing is provided with a heat insulation pad.

Preferably, the flight of the hollow screw is similar to that of an ordinary screw, the inner hole is a stepped structure, the inner hole near the screw head has a smaller diameter, and forms a shaping device for the pipe with the mandrel, and the inner hole at the other end has a larger diameter.

Preferably, the spray cooling device is mainly composed of a box cover, a nozzle, a guide wheel, a box frame and a box body; the box body and the box cover form a cooling water tank, and a plurality of nozzles are installed on the box cover at intervals. There are guide wheels.

Preferably, the roller-type traction mechanism is mainly composed of a traction frame, a driving wheel and a driven wheel; the driving wheel and the driven wheel are arranged on the traction frame, and a channel for pipe products is formed between the driving wheel and the driven wheel.

Preferably, the resistance heater is fixed on the outer wall of the barrel through screws, and its fixed positions correspond to the solid conveying section, the melting section and the metering section of the plasticizing system respectively.

Preferably, one end of the barrel is connected to one side of the end cover of the reduction box by screws; the other end of the barrel is connected to the support cover by screws.

Preferably, the surface of the distribution shuttle is smooth.

The extrusion molding method of small-diameter plastic pipes without weld marks using the device: when the motor rotates, the hollow screw rotates under the drive of the coupling and the reducer, and the flight of the hollow screw and the inner hole of the barrel form a plastic tube. The chemical system melts and plasticizes the material from the hopper, and transports it to the screw head in a quantitative, constant temperature, and constant pressure; under the action of the melt pressure, the melt enters the inner hole and the core of the screw through the shunt shuttle on the mandrel. In the annular space formed by the rods, a tube blank whose shape and size are basically consistent with the product is formed in the annular space; the continuous extrusion of the tube blank is realized under the traction of the melt pressure roller traction mechanism; the temperature distribution on the hollow screw is: The temperature from the screw head to the feeding section gradually decreases, the tube blank is shaped and initially cooled, and then the tube blank enters the spray cooling device for further cooling to obtain a tube product.

In the extrusion molding method of the small-diameter plastic pipe without weld marks of the present invention, the extrusion direction of the pipe is opposite to the flow direction of the melt during plasticization, and the melt does not need to pass through the support of the mandrel supporting device, thereby realizing the pipe extrusion without weld marks forming.

Compared with the existing pipe extrusion molding method and device, the present invention has the following advantages:

1. The axial length of the pipe extrusion device without weld marks is shortened, the equipment structure is more compact, the floor space is small, and the investment cost of the plant is low;

2. The pipe extrusion device without weld marks effectively improves the hoop strength of pipe products, which is conducive to reducing the wall thickness of pipes, reducing the amount of plastic materials, reducing costs and reducing white pollution under the premise of ensuring product performance;

3. Through the relative movement of the screw and the mandrel, a compound shear deformation with controllable strength is generated on the tube blank in the reverse direction of the circumference, so as to regulate the crystallization form and orientation structure of the tube and improve the performance of the product.

Description of drawings

Figure 1 is a schematic structural view of a small-diameter pipe extrusion molding device without weld marks.

Fig. 2 is a schematic diagram of the connection structure between the supportless mandrel and the end cap.

Fig. 3 is a schematic diagram of the structure of the hollow screw.

Fig. 4 is a sectional view along A-A in Fig. 3 .

Fig. 5 is a schematic structural diagram of a spray cooling device.

Fig. 6 is a structural schematic diagram of a roller-type traction mechanism.

The figure shows: frame 1, motor 2, coupling 3, reduction box 4, spray cooling device 5, roller traction mechanism 6, hollow transmission sleeve 7, hopper 8, barrel 9, hollow screw 10, Heater 11, mandrel 12, shunt shuttle 13, support cover 14, mandrel driving device 15, heat insulation pad 16, deep groove ball bearing 17, gland 18, melt 19, tube blank 20, box cover 21, nozzle 22, guide wheel 23, box frame 24, box body 25, traction frame 26, driving wheel 27, driven wheel 28 and pipe product 29.

detailed description

In order to better understand the present invention, the present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the scope described in the embodiments.

As shown in Figures 1 and 2, a small-diameter pipe extrusion molding device without weld marks includes a frame 1, a motor 2, a spray cooling device 5, a roller traction mechanism 6, a barrel 9, and a hollow screw 10. , mandrel 12, shunt shuttle 13 and support cover 14; two ends of frame 1 are respectively provided with reduction box 4 and mandrel driving device 15; motor 2 is connected with reduction box 4 through coupling 3; The hollow transmission sleeve 7, the hollow transmission sleeve 7 is the output shaft of the reduction box; one end of the barrel 9 is installed on one side of the end cover of the reduction box 4 through screw connection, and the spray cooling device 5 and the roller traction mechanism 6 are coaxial in sequence Installed on the other side of the end cover of the reduction box 4; a hopper 8 is provided on the material barrel 9, and the hopper 8 communicates with the inner hole of the material barrel 9; the inner hole of the material barrel 9 is coaxial with the hollow transmission sleeve 7 of the reduction box 4; The other end of the barrel 9 is connected with the support cover 14 by screws; the hollow screw 10 is installed in the inner hole of the barrel 9, and one end is fitted with the hollow transmission sleeve 7 of the reduction box 4 and connected by a flat key, and the other end extends into the support In the cover 14; the flight of the hollow screw 10 and the inner hole of the barrel 9 form a plasticizing system; the mandrel 12 is concentrically placed in the inner hole of the hollow screw 10, and the inner hole of the hollow screw 10 and the mandrel 12 form a ring The gap is the shaping device for the tube blank 20; the mandrel 12 is installed on the support cover 14, and the mandrel 12 extends out of the support cover 14 to connect with the mandrel driving device 15; the mandrel 12 is preferably installed on the support cover through a deep groove ball bearing 17 14, the outer side of the deep groove ball bearing 17 is provided with a gland 18, and the deep groove ball bearing 17 is fixed on the support cover 14 with the gland 18; Pads 16 reduce heat transfer in the direction of the mandrel drive 15 . A shunt shuttle 13 is processed on the mandrel 12 in the support cover 14, and the shunt shuttle 13 is a two-stage cone coaxial with the mandrel 12: the melt is formed on the outer surface of the shunt shuttle 13 and the inner hole of the barrel 9 The thin melt layer promotes the heat exchange between the melt and the barrel; at the same time, due to the change of the cross-sectional area of the melt flow, the melt produces compression/expansion, which improves the plasticizing and mixing effect. Since the surface of the diverter shuttle 13 is smooth and the mandrel 12 is installed on the support cover 14, there is no need for bracket parts to support the mandrel in the conventional pipe extrusion molding device, and the melt will not form multiple fluids when flowing through the diverter shuttle 13, thus No weld lines will be produced.

The resistance heater 11 is fixed on the outer wall of the barrel 9 by screws, and its fixed positions correspond to the solid conveying section, the melting section and the metering section of the plasticizing system respectively, and cooperate with the control system to meet the requirements of the solid conveying section, The temperature requirements of the melting section and the metering section.

As shown in Figures 3 and 4, the flight of the hollow screw 10 is similar to that of an ordinary screw, the inner hole is a stepped structure, and the diameter of the inner hole near the screw head is smaller, and forms a shaping device for the pipe with the mandrel. The tube blank 20 is basically the same shape and size as the tube product; the diameter of the inner hole at the other end is larger, which is used to reduce the friction between the inner hole and the tube blank and avoid the heat transfer to the screw during the cooling process of the tube blank, so as to ensure the plasticizing efficiency and stability The tube blank is shaped and initially cooled in the shaping device.

As shown in Figure 5, the spray cooling device 5 is mainly composed of a box cover 21, a nozzle 22, a guide wheel 23, a box frame 24 and a box body 25; the box body 25 and the box cover 21 form a cooling water tank, and a plurality of nozzles 22 Installed on the box cover 21, the box body 25 is provided with a guide wheel 23 for supporting and guiding the tube blank 20; the water from the nozzle 22 further cools the tube blank 20; the box body 25 is set on the box frame 24 .

As shown in Figure 6, the roller type traction mechanism 6 is mainly made up of traction frame 26, driving wheel 27 and driven wheel 28; The channel of the product 29; through the action of the friction force of the driving wheel 27, a certain traction force and traction speed are provided for the preliminarily shaped pipe product 29, so as to realize the traction of the product. The pipe blank enters the spray cooling device 5 and is further cooled to form a pipe product 29; the shape and size of the pipe blank 20 and the pipe product 29 are basically the same.

The extrusion molding process of small-diameter pipes without weld marks is as follows: when the motor 2 rotates, the hollow screw 10 rotates under the drive of the coupling 3 and the reducer 4, and the flight of the hollow screw 10 forms a shape with the inner hole of the barrel 9. The plasticizing system melts and plasticizes the material from the hopper 8, and transports the material to the screw head quantitatively, at a constant temperature and at a constant pressure; under the action of the melt pressure, the melt 17 passes through the shunt shuttle 13 on the mandrel 12 and enters the screw head. In the annular space formed by the inner hole of the screw 10 and the mandrel 12, a tube blank 20 whose shape and size are basically consistent with the product is formed in the annular space; under the traction of the melt pressure roller type traction mechanism 6, the continuous Extrusion: Since the temperature distribution on the hollow screw 10 is that the temperature from the screw head to the feed section gradually decreases, the tube blank is shaped and initially cooled, and then the tube blank enters the spray cooling device 5 for further cooling to obtain a shape, The pipe products 29 whose size and performance meet the usage requirements are finally cut and stacked to obtain the required products.

Referring to Figures 1 and 2, it can be seen that, unlike the conventional pipe extrusion molding method and equipment, on the one hand, the mandrel 12 and the shunt shuttle 13 are fixed on the support cover 14 through bearings, so there is no need for bracket parts to support the mandrel ; On the other hand, during plasticizing, the melt flows along the screw groove to the screw head, while the tube blank moves from the screw head to the screw tail. The shuttle 13 will not form multiple streams of fluid, so no weld lines will be formed when the tube blank is formed, thereby realizing the extrusion molding of pipes without weld lines. The invention has no weld marks in the pipe material, effectively improves the hoop strength of the pipe product, can reduce the wall thickness of the pipe material under the premise of ensuring the performance of the product, reduces the cost and reduces white pollution at the same time.

At the same time, the present invention makes full use of the space, the axial length of the pipe extrusion device is shortened, the equipment structure is more compact, and the plant investment cost is low; The shear deformation effect with controllable strength is generated in the reverse direction of the circumference, which is beneficial to the regulation of the condensed matter structure of the pipe, and enriches the means of regulating the performance of the pipe product.

The mandrel of the present invention can be driven by a motor to rotate in the inner hole of the screw, and the mandrel and the screw rotate in the same direction or in the opposite direction so as to produce a shearing deformation with controllable shear strength on the circumference of the inner wall of the tube blank in the opposite direction. The condensed matter structure can be adjusted to improve the strength of the pipe, especially the hoop strength.

Claims (9)

1. A small-caliber pipe extrusion molding device without weld marks, characterized in that it includes a frame, a motor, a spray cooling device, a roller traction mechanism, a barrel, a hollow screw, a mandrel, a shunt shuttle and a support cover; both ends of the frame are equipped with a reduction box and a mandrel driving device; the motor is connected to the reduction box through a coupling; a hollow transmission sleeve is provided in the reduction box; one end of the barrel is installed on one side of the end cover of the reduction box, The spray cooling device and the roller traction mechanism are coaxially installed on the outside of the other side of the end cover of the reduction box in turn; a hopper is provided on the material barrel, and the hopper communicates with the inner hole of the material barrel; the inner hole of the material barrel is connected to the hollow of the reduction box The transmission sleeve is coaxial; the other end of the barrel is connected to the support cover; the hollow screw is installed in the inner hole of the barrel, one end is matched with the hollow drive sleeve of the reduction box and connected by a flat key, and the other end extends into the support cover; The mandrel is concentrically placed in the inner hole of the hollow screw, and the inner hole of the hollow screw and the mandrel form a circular gap; the mandrel is installed on the support cover, and the mandrel extends out of the support cover to connect with the mandrel driving device; located on the support cover A shunt shuttle is processed on the inner mandrel, and the shunt shuttle is a two-section cone coaxial with the mandrel. 2. The small-diameter plastic pipe extrusion molding device without weld marks according to claim 1, characterized in that, the mandrel is installed on the support cover through a deep groove ball bearing, and the outer side of the deep groove ball bearing is provided with a press Cover; the inner side of the deep groove ball bearing is provided with a heat insulation pad. 3. The small-diameter plastic pipe extrusion molding device without weld marks according to claim 1, characterized in that, the flight of the hollow screw is similar to that of an ordinary screw, and the inner hole is a stepped structure, and the diameter of the inner hole close to the screw head Smaller, it forms the shaping device of the pipe with the mandrel, and the diameter of the inner hole at the other end is larger. 4. The small-diameter plastic pipe extrusion molding device without weld marks according to claim 1, wherein the spray cooling device is mainly composed of a box cover, a nozzle, a guide wheel, a box frame and a box body; The box body and the box cover form a cooling water tank, and a plurality of nozzles are installed on the box cover at intervals, and guide wheels are arranged in the box body. 5. The small-diameter plastic pipe extrusion molding device without weld marks according to claim 1, characterized in that the roller-type traction mechanism is mainly composed of a traction frame, a driving wheel and a driven wheel; the driving wheel and the driven wheel are arranged on the traction frame On the top, a channel for pipe products is formed between the driving wheel and the driven wheel. 6. The small-diameter plastic pipe extrusion molding device without weld marks according to claim 1, wherein the resistance heater is fixed on the outer wall of the barrel by screws, and its fixed positions correspond to the solid delivery of the plasticizing system section, melting section and metering section. 7. The small-diameter plastic pipe extrusion molding device without weld marks according to claim 1, characterized in that, one end of the material barrel is mounted on one side of the end cover of the reduction box through screw connection; the other end of the material barrel is connected to the support The cover is attached by screws. 8 . The small-diameter plastic pipe extrusion molding device without weld lines according to claim 1 , wherein the surface of the shunt shuttle is smooth. 9. A method for extrusion molding of small-diameter plastic pipes without weld marks using the device described in any one of claims 1-8, characterized in that, when the motor rotates, the hollow screw rotates under the drive of the coupling and the reducer , the flight of the hollow screw and the inner hole of the barrel form a plasticizing system to melt and plasticize the material from the hopper, and transport it to the screw head in a quantitative, constant temperature, and constant pressure; under the action of the melt pressure, the melt passes through the core The shunt shuttle on the rod enters the annular space formed by the inner hole of the screw and the mandrel, and forms a tube blank in the annular space whose shape and size are basically consistent with the product; it is realized under the traction of the melt pressure roller traction mechanism. Continuous extrusion of tube blanks; the temperature distribution on the hollow screw is such that the temperature from the screw head to the feed section gradually decreases, the tube blanks are shaped and initially cooled, and then the tube blanks enter the spray cooling device for further cooling to obtain pipe products .