Continuous forming high-compression-ratio paste polytetrafluoroethylene tube extrusion equipment

Abstract

The utility model discloses continuous forming high-compression-ratio paste PTFE pipe extrusion equipment, which comprises a feeding hole, a charging barrel and a forming die which are arranged in sequence, a screw rod is arranged in the charging barrel, the screw rod consists of a charging section, a melting section and a homogenizing section, the charging section is communicated with a discharging hole of a feeding machine, a screw groove of the melting section is shallower and shallower along the PTFE paste extrusion direction, and the homogenizing section is communicated with the discharging hole of the feeding machine. Namely, the closer to the forming die end, the more shallower the depth of the spiral groove, and the design is beneficial to improving the compression ratio of the material. And the first temperature sensor is arranged in the hollow part of the screw rod, so that the temperature of the screw rod is controlled more accurately. And the screw rod is heated in an electromagnetic induction mode, so that heat can be transferred to materials more uniformly. A second temperature sensor is assembled in the forming die and used for monitoring the temperature fluctuation condition in the extrusion process, and cooling efficiency of circulating water located outside the charging barrel is enhanced in the mode that the number of water pipe windings is increased in a gradient mode.

Description

TECHNICAL FIELD

[0001] The utility model relates to four fluorine pipe manufacturing technology field, concretely relates to a kind of high compression ratio paste four fluorine pipe extrusion equipment. BACKGROUND

[0002] Polytetrafluoroethylene (PTFE) has excellent chemical resistance, thermal stability, dielectric properties, non-stick, weather and friction resistance, and low surface tension, excellent electrical insulation, has become indispensable engineering materials in industry. Four fluorine tube usually adopts mould pressing, extrudes into blank after mixing extrusion aid and polytetrafluoroethylene into paste, then obtains product by sintering. However, conventional mixing extruder has problems such as uneven material mixing, unstable heating, especially when extruding paste four fluorine tube blank, since paste four fluorine tube needs relatively high-precision temperature control, its shortcomings are particularly obvious, paste blank is prone to uneven mixing of extrusion aid and fluoroplastic, which will lead to product cracking during subsequent pressure sintering to remove extrusion aid.

[0003] The compression ratio of polytetrafluoroethylene refers to the ratio of the cross-sectional area of the extruder barrel portion to the cross-sectional area after extrusion sintering during processing. PTFE with high compression ratio usually has better mechanical properties, such as compressive strength and compression modulus, which better meets the storage and transportation requirements of corresponding chemicals in the semiconductor industry. Increasing the compression ratio is usually achieved by increasing the diameter of the push barrel of the extrusion equipment. However, increasing the diameter of the barrel also causes problems such as uneven mixing of fluoroplastic and extrusion aid and inaccurate temperature control. SUMMARY

[0004] The utility model aims at providing a kind of continuous forming high compression ratio paste four fluorine tube extrusion equipment, by increasing the diameter of the barrel to increase the compression ratio of paste four fluorine tube blank, and improving extruder, so that it realizes uniform mixing and accurate heating of polytetrafluoroethylene and extrusion aid.

[0005] To achieve the above objectives, the technical solutions provided by the utility model are as follows:

[0006] A kind of continuous forming high compression ratio paste four fluorine tube extrusion equipment, including feeding port, barrel, forming die which are sequentially arranged, characterized by: screw is arranged in the barrel and connected with motor spindle, the screw is connected to the discharge port of feeder, the screw groove of the screw becomes shallower and shallower along the extrusion direction of PTFE paste, the feeder and motor are connected with PLC control system by circuit, the diameter of the barrel is further increased by 25% compared with conventional equipment.

[0007] Further technical solutions also include that the inner wall of the barrel is provided with helical line, and the direction of the helical line is opposite to the helical direction of the screw.

[0008] The electromagnetic induction heater is connected with the PLC control system through a circuit, the electromagnetic induction is a non-contact heating process, and has many advantages, including high temperature rising speed, stable temperature, controllable temperature falling speed, etc.

[0009] Further technical solutions also include that the screw rod is hollow, and a first temperature sensor is arranged in the cavity of the screw rod.

[0010] Further technical solutions also include that a temperature and pressure integrated sensor connected with the PLC control system through a circuit is arranged in the barrel, the temperature and pressure integrated sensor is arranged in the barrel to monitor the temperature and pressure of PTFE, and the accurate temperature of the paste PTFE pipe blank during extrusion is maintained.

[0011] Further technical solutions also include that a circulating water cooling device connected with the PLC control system through a circuit is arranged outside the barrel and tangent to the barrel, the circulating water cooling device comprises a water pipe winding, and the water pipe winding gradually increases along the extrusion direction of polytetrafluoroethylene, so that segmented cooling is realized.

[0012] The water pipe winding is arranged tangent to the barrel to realize fast cooling and accurate temperature control, and the temperature of the barrel inevitably rises due to heat transfer; preferably, the water pipe winding is made of copper pipe, the copper pipe has good heat dissipation effect, heat is transferred to air and circulating water, the amount of cooling water is adjusted, and the number of water pipe windings is increased to solve the problem.

[0013] To improve the compression ratio of the paste PTFE pipe blank, the technical solutions of the utility model also include that the forming die comprises a flow channel, a core rod and a die head, the second temperature sensor is embedded in the inner side of the die head, and the second temperature sensor is connected with the PLC control system through a circuit.

[0014] Further technical solutions also include that the flow channel is arranged in a streamline shape, the shape of the core rod is adapted to the flow channel, and the spacing between the core rod and the flow channel gradually decreases.

[0015] Further technical solutions also include that the flow channel is internally provided with a spiral line.

[0016] The utility model has the advantages and beneficial effects that:

[0017] 1、Through reasonable design screw and the structure and proportion of the barrel, can significantly improve the paste four fluorine tube blank compression effect, and make PTFE particle and auxiliary agent uniform mixing, is favorable for subsequent sintering forming when obtaining higher density four fluorine tube.

[0018] 2、Introduce advanced electromagnetic induction heating technology and multipoint temperature sensing system, effectively improve the temperature control precision in the extrusion process, in turn guarantee the consistency of blank.

[0019] 3、Improved circulating water cooling mechanism improves the temperature control precision and efficiency, helps to speed up the speed of blank setting type, and reduces the defective rate. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the internal structure schematic view of the embodiment of the utility model;

[0021] Figure 2 It is the internal structure schematic view of the screw of the embodiment of the utility model;

[0022] Figure 3 It is the cross section structure schematic view along A-A of the embodiment of the utility model;

[0023] Figure 4 It is the local enlarged view of a place of the embodiment of the utility model;

[0024] Figure 5 It is the structure schematic view of the barrel of the utility model;

[0025] In the drawing:

[0026] 1- feed inlet, 2- barrel, 3- forming die, 4- screw, 5- feeder discharge port, 6- motor, 7- screw groove, 8- electromagnetic induction heater, 9- first temperature sensor, 10- circulating water cooling system, 11- temperature and pressure integrated sensor, 12- core rod, 13- flow channel, 14- die, 15- helical line, 16- second temperature sensor. DETAILED DESCRIPTION

[0027] The specific implementation of the utility model is further described below in combination with the drawings and examples. The following examples are only used to more clearly illustrate the technical scheme of the utility model, and cannot limit the protection scope of the utility model. Example

[0028] Please refer to Figures 1-5The utility model provides a kind of continuous forming high compression ratio paste four fluorine pipe extrusion equipment, including feed inlet 1, barrel 2, forming die 3 arranged in sequence, screw 4 is provided in barrel 2, the screw 4 is communicated with feeder discharge opening 5, screw channel 7 of screw 4 is increasingly shallow along the PTFE paste extrusion direction, feeder is connected with PLC control system by circuit.In barrel 2 outside, electromagnetic induction heater 8 is connected with PLC control system circuit, the screw 4 is made of magnetically conductive metal, heating is realized to screw 4 by electromagnetic induction, electromagnetic induction heater 8 is connected with PLC control system by circuit.Screw 4 is heated using electromagnetic induction mode, can more evenly transfer heat to material, the diameter of barrel 2 is increased by about 25% compared to general four fluorine tube blank extrusion equipment, in the same specification four fluorine tube blank process, the growth of barrel diameter can improve the compression ratio and density of paste four fluorine tube.

[0029] Screw 4 is hollowly arranged, and a first temperature sensor 9 is arranged in the cavity of the screw 4.The first temperature sensor 9 is connected with the PLC control system by a circuit, and the first temperature sensor 9 includes a plurality of thermocouples connected in series, for expanding the signal range, improving the measurement resolution and measurement accuracy, and monitoring and adjusting the temperature and temperature change of the screw 4 in real time through the PLC control system.

[0030] A circulating water cooling device 10 is arranged outside the barrel 2 and tangent to the barrel 2 and connected with the PLC control system by a circuit, and the circulating water cooling device 10 includes a water pipe winding, which gradually increases along the extrusion direction of the polytetrafluoroethylene paste blank, so as to realize segmented cooling. The barrel 2 needs to melt and mix the polytetrafluoroethylene particles and the extrusion aid in the initial stage, and when approaching the forming die 3, the PTFE paste needs to be cooled by about 20% so as to be formed, while avoiding the continuous heat absorption of the PTFE in the barrel 2 from affecting the quality. Therefore, segmented cooling is adopted to improve the quality of the paste four fluorine tube. A temperature and pressure integrated sensor 11 connected with the PLC control system by a circuit is embedded in the barrel 2 to monitor the temperature and pressure of the PTFE simultaneously.

[0031] The forming die includes a mandrel 12, a runner 13, and a die head 14, and a second temperature sensor 16 is embedded in the inner side of the die head 14 and connected with the PLC control system by a circuit. The runner 13 is streamline-shaped, and a helical line 15 is arranged in the runner 13. The spacing between the mandrel 12 and the runner 13 gradually decreases. The streamline-shaped runner 13 can reduce the resistance of the melt during the flowing process, so that the melt flows more smoothly through the die head. The arrangement of the helical line 15 guides the melt to produce a certain rotational motion during the flowing process, so as to improve the uniformity of mixing. The gradually decreasing spacing between the mandrel 12 and the runner 13 can slowly improve the compactness of the four fluorine tube, so as to be beneficial to improving the density of the four fluorine tube blank.

[0032] The feeding machine is a high-precision feeding device, PTFE paste and extrusion aid are put into the extrusion equipment by the feeding machine, the discharge port 5 of the feeding machine is directly connected with the feeding port 1 of the extruder to solve the problem of uneven feeding, the electromagnetic induction heater 8 can be a coil, an alternating magnetic field is generated by non-contact power supply, the screw 4 is inductively heated, then PTFE particles and extrusion aid are transported to the die along the screw groove 7 of the screw 4, since the depth of the screw groove 7 gradually decreases, and the cavity formed between the barrel 2 and the screw 4 also gradually decreases, in order to improve the compression ratio, the diameter of the barrel is increased by 25% compared with conventional equipment, and a helical line opposite to the helical direction of the screw is arranged on the inner wall of the barrel, in addition to the thrust of the screw, the arrangement of the helical line makes the material rotate in the direction of extrusion of the screw, further improving the uniformity of the paste blank, so that the sintered PTFE pipe has fewer defect points under the premise of improving the density.

[0033] A first temperature sensor 9 composed of a plurality of thermocouples connected in series is arranged in the middle of the screw 4, and is connected with the PLC control system through a circuit, the PLC control system receives the temperature signal of the first temperature sensor 9, adjusts the strength of the alternating magnetic field generated by the electromagnetic induction heater 8 connected with the circuit in real time, and finely adjusts the melting temperature. It should be noted that the barrel will also be heated by the paste, which will cause the temperature to rise, and when the PTFE paste is located at the end of the screw, this situation will be even worse due to the increase in the compression ratio, which will be detrimental to the formation of the blank. The above problem is solved by gradually increasing the number of pipe windings of the circulating water cooling system, and the circulating water cooling system can also be linked with the PLC program design, temperature and / or pressure sensors to further improve the technical effect.

[0034] When the material passes through the flow channel 13, the thickness of the cavity wall formed by the flow channel 13 and the mandrel 12 also gradually decreases, which is used to improve the regularity and tightness of the blank, and further, the inner wall of the flow channel 13 is also provided with a helical line 15 for improving the flow and extrusion characteristics of the PTFE paste, so that it changes from smooth flow to also has the effect of up and down, making the blank extrusion more uniform, and the flow channel is finally smoothly connected to the die to extrude the blank into a PTFE pipe, which is further sintered to obtain the product.

[0035] The above only describes preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the technical principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A continuous forming high-compression-ratio PTFE tube extrusion device, comprising a feed inlet, a barrel, and a forming die arranged sequentially, characterized in that: A screw rod is arranged in the barrel and connected with the main shaft of the motor, the screw rod is connected with the discharge port of the feeder, the depth of the screw groove gradually decreases along the extrusion direction of the PTFE paste, and the feeder and the motor are connected with the PLC control system through a circuit.

2. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 1, characterized in that: An electromagnetic induction heater is arranged outside the barrel and connected with the PLC control system through a circuit.

3. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 1, characterized in that: The screw rod is hollow, a first temperature sensor is arranged in the cavity of the screw rod, the first temperature sensor is connected with the PLC control system through a circuit, and the first temperature sensor comprises a series-connected thermocouple.

4. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 1, characterized in that: A circulating water cooling device is arranged outside the barrel and connected with the PLC control system through a circuit, the circulating water cooling device comprises a water pipe winding, and the number of the water pipe windings gradually increases along the extrusion direction of the polytetrafluoroethylene.

5. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 1, characterized in that: A temperature and pressure integrated sensor is embedded in the barrel and connected with the PLC control system through a circuit.

6. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 1, characterized in that, A helical line is arranged on the inner wall of the barrel, and the direction of the helical line is opposite to the helical direction of the screw rod.

7. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 1, characterized in that: The forming die comprises a runner, a mandrel and a die, a second temperature sensor is embedded in the inside of the die, and the second temperature sensor is connected with the PLC control system through a circuit.

8. The continuous forming high compression ratio paste tetrafluoro pipe extrusion equipment according to claim 7, characterized in that: The runner is arranged in a streamline shape, the shape of the mandrel is adapted to the runner, and the spacing between the mandrel and the runner gradually decreases.

9. The continuous forming high compression ratio paste four-fluorine tube extrusion equipment according to claim 7, characterized in that: A helical line is arranged in the runner.

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