CN206690514U - A kind of special extrusion screw rod of heat-proof polythene - Google Patents

Abstract

The utility model discloses a kind of special extrusion screw rod of heat-proof polythene, the screw rod includes feeding section, compression section, the first metering section, decompression section, the second metering section, mixing section and screw head, the feeding section, compression section, the first metering section, decompression section, the second metering section, mixing section and screw head are sequentially connected, and one start screw structure is used on the feeding section, decompression section, the first metering section and the second metering section；The compression section uses the double thread structure being made up of main thread and added thread, and the added thread intersects with main thread in feeding section side, do not intersected in the first metering section side with main thread；The mixing section uses prismatoid structure.The utility model is simple in construction, easy to use, melting efficiency is high, plasticizing is uniform, conveying capacity is high, and yield height and stable yield under high rotating speed.

Description

A kind of special extrusion screw rod of heat-proof polythene

Technical field

A kind of plastic extruding screw is the utility model is related to, especially a kind of special extrusion screw rod of heat-proof polythene, is belonged to The production field of heat-proof polythene tubing.

Background technology

As shown in figure 1, being the structural representation of existing common polyolefin extrusion screw rod, its screw rod is single thread structure, Feeding section 1, compression section 2, metering section 3 and screw head 4 are generally comprised, when plastics enter in feeding cylinder from hopper, so as to which material enters To feeding section 1, under screw rod turning effort, compression section is gradually fed forward to by material tube inner wall and screw surface rubbing action 2, the spiral groove depth of compression section 2 is shoaled, and solid material is further consolidated, while in barrel external heat, and in screw rod and barrel Under wall friction shear action, material heats up and starts to melt, and the material after melting enters metering section 3, and this section is by material dosing From the extrusion plastic melt of screw head 4.

Application publication number is CN101774269A Chinese invention patent application, discloses a kind of high speed PB (Polybutene, polybutene) tube single screw, including feeding section, divergence type melt zone and mixed milling type extruding zone, divergence type Melt zone is provided with a main spiral shell rib and two secondary spiral shell ribs, and which solving existing PB tubing screw rod, productivity ratio is difficult to carry at high speeds The high, phenomenon that plasticizing quality is also bad, melt temperature is too high, has obtained what plasticizing quality was good, productivity ratio is high (300Kg/ hours) PB molten plastics.

Authorization Notice No. is CN201669874U Chinese utility model patent, discloses one kind and is used for polyacrylic high speed Single-screw extruder, screw rod are divided into feed zone, compression segregation section, metering section, mixing section from rear end to front end, compress segregation section Provided with main spiral shell rib and secondary spiral shell rib.The beneficial effect of the utility model against existing technologies is to reduce the Geometric compression of compression section Than improving the conveying capacity of material, with reference to the screw rod of high speed rotation, material being greatly shortened and has been plastified from solid-state into viscous state Fusion time, reduce polyacrylic extrusion temperature, pressure of the polypropylene in head improved, so as to enhance extruded product Material density, polyacrylic high speed high yield extrusion can not only be realized, while can also realize polyacrylic low temperature extrusion.

Authorization Notice No. be CN201317096Y Chinese utility model patent, disclose a kind of PE (Polyethylene, Polyethylene) plastic pipe high-yield extrusion screw, using three stage structure, it is followed successively by feeding section, melt zone, extruding zone, feeding section Using one start screw structure, melt zone uses the divergence type structure of double thread, and extruding zone uses mixed milling type structure.Feeding section is adopted With single-threaded structure, be advantageous to the stable conveying of high speed of material；Melt zone uses the divergence type structure of double thread, favorably In the fusion plastification of material；Extruding zone uses the structure of mixed milling type, is advantageous to mixing and the high yield extrusion of material.

Authorization Notice No. is CN203665916U Chinese utility model patent, discloses a kind of plastic extrusion single screw rod. Including feeding section, melting segregation section, barrier screen and mixing section, the feeding section, melting segregation section, barrier screen and mixing section are all provided with There is spiral shell rib, the feeding section is two pitch airscrew structure.The utility model can reduce the friction slip between plastic pellet, improve screw rod Material conveying efficiency；Increased step by step by the pitch of double spiral shell rib sections, realize melt pressure in feeding section and melting segregation section spiral shell rib Transition step by step, it is ensured that the pressure stability of melt；Spiral shell rib bottom footpath is changed from small to big, and the feeding space formed between blanking bushing subtracts It is few, the melt for melting segregation section is pushed ahead so as to produce bigger pressure.

At present, extrusion screw rod is disadvantageous in that in the prior art：1) pressure of whole screw rod is all by the pressure of feeding section Power is established, and when head pressure is big, this will reduce the charging capability of screw rod；2) screw rod yield is influenceed substantially by head pressure, modeling Material extrusion fluctuation is big；3) plasticizing effect of material is bad, and melting efficiency is low, and mixing is not uniform enough, and yield is not high；4) yield is high When, plasticizing is poor, the melt temperature difference is bigger, Dryland crops are bigger.

Heat-proof polythene (Polyethylene of raised temperature resistance, PE-RT) raw material, As a kind of polythene material, the degree of shear shinning is less than polypropylene (Polypropylene, PP) in shear history, because And more preferable shear effect is needed in high-speed production to meet that raw material plasticizing requires；But and due to heat-proof polythene raw material Narrow molecular weight distribution, processing temperature scope it is small, in the case where being higher by decomposition temperature, oxidative degradation just occurs in the short time, so must It must avoid Strong shear being present, but its work in-process must be made fully to plastify.Therefore current polyolefin extrusion screw rod Be not suitable for production heat-proof polythene tubing.Therefore need to design a kind of new and effective heat-proof polythene screw rod to improve production effect Rate.

Utility model content

The defects of the purpose of this utility model is to overcome above-mentioned prior art, there is provided a kind of heat-proof polythene is special Extrusion screw rod, the screw-rod structure is simple, easy to use, melting efficiency is high, plasticizing is uniform, conveying capacity is high, and is produced under high rotating speed Amount height and stable yield.

The purpose of this utility model can be achieved through the following technical solutions：

A kind of special extrusion screw rod of heat-proof polythene, including feeding section, compression section and screw head, in addition to the first metering Section, decompression section, the second metering section and mixing section, the feeding section, compression section, the first metering section, decompression section, the second metering section, Mixing section and screw head are sequentially connected, and single head spiral shell is used on the feeding section, decompression section, the first metering section and the second metering section Line structure；The compression section uses the double thread structure being made up of main thread and added thread, and the added thread is feeding Section side is intersected with main thread, is not intersected in the first metering section side with main thread；The mixing section uses prismatoid structure.

Further, one start screw structure on the feeding section forms charging spout, the single head on first metering section Helicitic texture forms the first measuring tank, and the one start screw structure in the decompression section forms relief groove, on second metering section One start screw structure form the second measuring tank, the double thread structure on the compression section forms consolidating of being connected with charging spout Phase groove, and the liquid phase groove being connected with the first measuring tank.

Further, bottom land of the bottom land of the solid phase groove along charging spout extends to the bottom land direction of the first measuring tank, Gu The width of phase groove gradually decreases from feeding section to the first metering section direction, solid phase well width and charging groove width in feeding section side Spend identical, the solid phase well width in the first metering section side is the first metering 0.1~0.2 times of well width；The liquid phase groove Bottom land direction of the bottom land from the added thread appearance of feeding section side towards the first measuring tank extends, and the width of liquid phase groove is from charging Section to the first metering section direction gradually increases, and the liquid phase well width in feeding section side is the 0.06~0.15 of charging well width Times, the liquid phase well width in the first metering section side is the first measure well width 0.7~0.9 times.

Further, the depth of the charging spout and the depth of relief groove are all higher than the depth of the first measuring tank, and described The depth of two measuring tanks is less than the depth of relief groove.

Further, the width of the charging spout is less than outer screw diameter, first measuring tank, relief groove and the second metering The width of groove is all higher than outer screw diameter.

Further, the external diameter of added thread is smaller 2.5-5mm than the external diameter of main thread on the compression section.

Further, the helical pitch of main thread and the helical pitch of added thread are unequal, and the helical pitch of main thread is outer screw diameter 1.1~2.1 times, the helical pitch of added thread is 0.8~1.8 times of outer screw diameter.

Further, the cross sectional shape of the mixing section is rectangle, and the area of its bottom surface is more than the area of top surface, the ladder Physique structure is made up of multiple prismatoids, and the spacing between the adjacent prismatoid of any two is identical, and multiple prismatoids are in screw rod It is divided into multiple rows of, the prismatoid of each row annular array on screw rod circumference on axial direction.

Further, the effective length of the screw rod is 34~40 times of outer screw diameter, and the length of the feeding section is spiral shell 5~10 times of bar external diameter, the length of the compression section are 10~21 times of outer screw diameter, and the length of first metering section is spiral shell 2~6 times of bar external diameter, the length of the decompression section are 1~5 times of outer screw diameter, and the length of second metering section is screw rod 5~11 times of external diameter, the mixing section are 2~8 times of outer screw diameter.

The utility model compared with prior art, has the following advantages that and beneficial effect：

1st, in extrusion screw rod of the present utility model, feeding section uses one start screw structure, improves charging capability, compression section Using the double thread structure being made up of main thread and added thread, added thread intersects in feeding section side with main thread, First metering section side is not intersected with main thread, the double thread structure by optimization, is enhanced fusion plastification effect, is improved Material improves plasticizing capacity in the clogging of compression section, and mixing section uses prismatoid structure, has immixture to material, The distributed rendering ability of screw rod is strengthened, and improves that uniformity in length and breadth on direction, melting effect be good, good dispersion.

2nd, in extrusion screw rod of the present utility model, the one start screw structure of feeding section forms charging spout, the first metering section One start screw structure forms the first measuring tank, and the double thread structure of compression section forms the solid phase groove communicated with charging spout, and The liquid phase groove communicated with measuring tank, the solid-phase material entered from charging spout can smoothly enter compression section, and charging will not be produced It is raw to hinder, cross added thread under screw rod operating and under barrel external heat, after solid-phase material melting and enter liquid phase groove, improve Fusion plastification effect of the material in barrel, and the material in solid phase groove can be persistently heated, increases solid-phase material Heat exchange area, the solid-phase material not melted on a small quantity can also smoothly enter metering section in, strong shearing will not be produced Power hinders charging, shortens melting length and relative reduction melt temperature on the whole, is advantageous to low temperature extrusion, avoids material Overheat.

3rd, in extrusion screw rod of the present utility model, the one start screw structure for depressurizing section forms relief groove, the depth of relief groove More than the depth of the first measuring tank, because relief groove is deeper, reduce influence of the head pressure to feeding section charging capability, reduce Pressure in machine barrel, reduces the abrasion of screw rod and machine barrel.

4th, extrusion screw rod effective length of the present utility model is 34~40 times of outer screw diameter, it is seen that has larger major diameter Than that can improve the rotating speed of screw rod, ensure residence time of the material in barrel under screw rod high-speed state, it is fully moulded Change, so as to improve extrusion capacity.

5th, extrusion screw rod of the present utility model is simple in construction, reasonable in design, can obtain high rotating speed, be high than yield, plasticizing The heat-proof polythene tubing that quality is good, accurate measurement, melt temperature are low, highest extrusion capacity are logical with same specification up to 550kg/h Compared with single screw rod, melt temperature reduces 3 DEG C, can play the preferably scattered effect with distribution, color masterbatch pigment can be with original Material is well mixed, and coloring effect is good, and the heat-proof polythene tubing presentation quality produced is good, and outer wall light is without lines, inwall light Sliding amixis line, end face is without Appearance quality defects such as stains.

Brief description of the drawings

Fig. 1 is the structural representation of extrusion screw rod in the prior art

Fig. 2 is the structural representation of the special extrusion screw rod of heat-proof polythene of the utility model embodiment 1.

Fig. 3 is the structural representation of the feeding section of the special extrusion screw rod of heat-proof polythene of the utility model embodiment 1.

Fig. 4 be the utility model embodiment 1 the special extrusion screw rod of heat-proof polythene in compression section structural representation.

Fig. 5 be the utility model embodiment 1 the special extrusion screw rod of heat-proof polythene in the first metering section structural representation Figure.

Fig. 6 is the structural representation that section is depressurized in the special extrusion screw rod of heat-proof polythene of the utility model embodiment 1.

Fig. 7 be the utility model embodiment 1 the special extrusion screw rod of heat-proof polythene in the second metering section and mixing section Structural representation.

In Fig. 1,1- feeding sections, 2- compression sections, 3- metering sections, 4- screw heads；

In Fig. 2~Fig. 7,5- feeding sections, 51- charging spouts, 6- compression sections, 61- solid phase grooves, 62- liquid phase grooves, 63- main threads, 64- added threads, the metering sections of 7- first, the measuring tanks of 71- first, 8- decompression sections, 81- relief grooves, the metering sections of 9- second, 91- the Two measuring tanks, 10- mixing sections, 11- screw heads.

Embodiment

The utility model is described in further detail with reference to embodiment and accompanying drawing, but implementation of the present utility model Mode not limited to this.

Embodiment 1：

As shown in Figure 2 to 7, the special extrusion screw rod of the heat-proof polythene of the present embodiment includes feeding section 5, compression section 6, the One metering section 7, decompression section 8, the second metering section 9, mixing section 10 and screw head 11, the feeding section 5, compression section 6, first are measured Section 7, decompression section 8, the second metering section 9, mixing section 10 and screw head 11 are sequentially connected, outer screw diameter 70mm, screw rod it is effective Length is 38 times of outer screw diameter, and larger draw ratio (the ratio between spiro rod length and outer screw diameter) can ensure in the high rotating speed of screw rod Residence time of the material in barrel, makes it fully plastify under state.

The feeding section 5 uses one start screw structure, and one start screw structure forms charging spout 51, and the width of charging spout 51 is small In outer screw diameter, and keep constant, the depth of charging spout 51 is 0.12 times of outer screw diameter, and keeps constant, and the width of thread is 0.08 times of outer screw diameter, the length of feeding section 5 is 6 times of outer screw diameters, due to using one start screw structure, can improve charging energy Power.

First metering section 7 uses one start screw structure, and one start screw structure forms the first measuring tank 71, the first metering The width of groove 71 is more than outer screw diameter, and keeps constant, and the depth of the first measuring tank 71 is 0.1 times of outer screw diameter, less than charging The depth of groove 51, and keep constant, the width of thread is 0.08 times of outer screw diameter, and the length of the first metering section 7 is outside 3 times of screw rods Footpath；Because the depth of charging spout 51 is more than the depth of the first measuring tank 71, appropriate compression ratio can be formed.

Led using the double thread structure being made up of main thread 63 and added thread 64, main thread 63 compression section 6 Journey and the helical pitch of added thread 64 are unequal, and the helical pitch of main thread 63 is 1.1~2.1 times of outer screw diameter 64, added thread Helical pitch be 0.8~1.8 times of outer screw diameter, the pitch of the main thread 63 of whole compression section 6 is different, same added thread 64 Pitch is also different, and the added thread 64 intersects in the side of feeding section 5 with main thread 63, the side of the first metering section 7 not with master Screw thread 63 is intersecting, forms the solid phase groove 61 being connected with charging spout 51, and the liquid phase groove 62 being connected with the first measuring tank 71, The solid-phase material entered from charging spout 51 can smoothly enter compression section 6, obstruction will not be produced to charging, under screw rod operating And cross added thread 64 under barrel external heat, after solid-phase material melting and enter liquid phase groove 62, material is improved in barrel Fusion plastification effect, and the material in solid phase groove 61 can be persistently heated, increases the heat exchange area of solid-phase material, A small amount of solid-phase material not melted smoothly can also enter in the first metering section 7, will not produce strong shearing force or resistance Hinder charging, shorten melting length and relative reduction melt temperature on the whole, be advantageous to low temperature extrusion, avoid material from overheating；

Bottom land of the bottom land of solid phase groove 61 along charging spout 51 extends to the bottom land direction of the first measuring tank 71, solid phase groove 61 Width gradually decreases from the direction of the metering section of feeding section 5 to the first 7, the width of solid phase groove 61 and charging spout 51 in the side of feeding section 5 Width is identical, and the width of solid phase groove 61 in the side of the first metering section 7 is 0.1~0.2 times of the width of the first measuring tank 71；Liquid phase groove 62 bottom land extends from the added thread appearance of feeding section side towards the bottom land direction of the first measuring tank 71, the width of liquid phase groove 62 Degree gradually increases from the direction of the metering section of feeding section 5 to the first 7, and the present embodiment is gradually increased to close to the first measuring tank 71 from 3mm Width, the width of liquid phase groove 62 in feeding section side is 0.06~0.15 times of the width of charging spout 51, in the first metering section 7 one The width of liquid phase groove 62 of side is 0.7~0.9 times of the width of the first measuring tank 71；The width of solid phase groove 61 is gradually reduced, liquid phase groove 62 Width gradually increases, and can effectively improve the stability that material is run in screw rod, is advantageous to run at high speed；

The external diameter of added thread 64 is smaller 4.0mm than the external diameter of main thread 63, will not produce strong shearing force, be advantageous to spiral shell Bar high-speed rotation；The width of main thread 63 is 0.08 times of outer screw diameter, and the width of added thread 64 is 0.05 times of outer screw diameter, entirely The length of compression section 6 is 17 times of outer screw diameters, advantageously ensures that main thread 63 promotes solid-phase material mobile and promotes its melting, together When the convenient solid-phase material melted be attached screw thread 64 and separate.

The decompression section 8 uses one start screw structure, and decompression section 8 separates the first metering section 7 and the second metering section 9, can With independent design compression ratio and the depth of thread, the purpose of decompression section 8 is to reduce the pressure in extruder barrel, even if so doing is Very high speed can also have constant specific discharge, be adapted to high speed extrusion；One start screw structure forms relief groove 81, relief groove 81 width is more than outer screw diameter, and the present embodiment is 1.2 times of outer screw diameters, and keeps constant, the depth ratio first of relief groove 81 The big 2mm of depth of measuring tank 71, and constant, screw rod stable yield under high rotating speed is kept, and the influence with speed that is not stressed； The width of thread is 0.08 times of outer screw diameter, and the length of decompression section 8 is 2 times of outer screw diameters.

Second metering section 9 uses one start screw structure, and one start screw structure forms the second measuring tank 91, the second metering The width of groove 91 is more than outer screw diameter, and the present embodiment is 1.2 times of outer screw diameters, and keeps constant, the depth of the second measuring tank 91 For 0.08 times of outer screw diameter, less than the depth of relief groove 81, and keep constant；The width of thread is 0.08 times of outer screw diameter, second The length of metering section 9 is 7 times of outer screw diameters.

The cross sectional shape of the mixing section 10 is rectangle, and the area of its bottom surface is more than the area of top surface, and mixing section 10 uses Prismatoid (trapezoidal polyhedron) structure, the prismatoid structure are made up of 48 prismatoids, the adjacent prismatoid of any two Between spacing it is identical, 48 prismatoids are divided into 6 rows upwards in screw shaft, and each row has 8 prismatoids annular on screw rod circumference Arrangement；The length of mixing section 10 is 3 times of outer screw diameters.

The special extrusion screw rod operation principle of heat-proof polythene of the present embodiment is as follows：

1) material enters the feeding section 5 of screw rod from hopper, under screw speed effect, is gradually pushed to screw head 11 and quilt Compress, while gradually melted under the shearing of screw rod and barrel and external heater effect；

2) in the compression section 6 of screw rod, material starts to melt in course of conveying, under the promotion of screw rod, molten thing Material is crossed added thread 64 and entered in liquid phase groove 62, and the solids not melted are attached screw thread 64 and blocked, still in solid phase In groove 61, so as to the feed separation realized molten material and do not melted, in the place that solid phase groove 61 and liquid phase groove 62 are converged Solution material is formed, now basic melting is completed, and the plastics and solid plastic melted are separated so that the modeling melted The shearing for expecting to be subject to reduces, and so as to realize that low temperature is extruded, this is also to realize that running at high speed for screw rod provides condition；

3) after the first metering section 7 and decompression section 8, in the second metering section 9 of screw rod, under the promotion of screw thread, due to It is longer, easily establish higher melt pressure, can accurate as measuring pump, quantitative melt conveying material, increase positive stream, subtract Few pressure current and leakage current, make to plastify more fully evenly；

4) on the one hand it is that prismatoid smashes solid material in the mixing section 10 of screw rod, destroys melt, upset solid and liquid The two-phase flow of body, and stream is repeatedly separated and converged, change direction and VELOCITY DISTRIBUTION of the stream in barrel, make solid phase It is sufficiently mixed with liquid phase, increases the heat transfer area between solid phase and liquid phase, and certain resistance and fricting shearing are produced to material, is made Solid phase fusion, on the other hand it is that material is subjected to repeated segmentation, shunts and converges, additive, color masterbatch is disperseed so as to increase Property.

According to experiment, compared with common screw, the radial temperature difference of extrudate can reduce 1~3 DEG C, and transverse temperature difference can reduce 2 ~5 DEG C；Solid phase draw heat constantly from melt in melting process, it is possible to reduce the temperature of melt, material is carried out more Secondary segmentation, shunt and converge, change of the material in motion process on its direction and position, enable in material different component very Disperseed and mixed well, thus well mixed and low temperature extrudate can be obtained.

Embodiment 2：

The present embodiment is mainly characterized by：The external diameter of added thread 64 is smaller than the external diameter of main thread 63 on compression section 6 2.5mm.Remaining is the same as embodiment 1.

Embodiment 3：

The present embodiment is mainly characterized by：The external diameter of added thread 64 is smaller 5mm than the external diameter of main thread 63 on compression section 6. Remaining is the same as embodiment 1.

Embodiment 4：

The present embodiment is mainly characterized by：The effective length of the screw rod is 34 times, and the length of feeding section 5 is outer screw diameter 5 times, the length of compression section 6 is 11 times of outer screw diameter, and the length of the first metering section 7 is 6 times of outer screw diameter, depressurizes section 8 Length be 5 times of outer screw diameter, the length of the second metering section 9 is 5 times of outer screw diameter, and mixing section 10 is the 2 of outer screw diameter Times.Remaining is the same as embodiment 1.

Embodiment 5：

The present embodiment is mainly characterized by：The effective length of the screw rod is 40 times, and the length of feeding section 5 is outer screw diameter 4 times, the length of compression section 6 is 15 times of outer screw diameter, and the length of the first metering section 7 be 6 times of outer screw diameter, depressurizes section 8 Length is 5 times of outer screw diameter, and the length of the second metering section 9 is 6 times of outer screw diameter, and mixing section 10 is 4 times of outer screw diameter. Remaining is the same as embodiment 1.

In summary, extrusion screw rod of the present utility model is simple in construction, reasonable in design, can obtain high rotating speed, be high than production Amount, the heat-proof polythene tubing that plasticizing quality is good, accurate measurement, melt temperature are low, highest extrusion capacity are and same up to 550kg/h The general single screw rod of specification is compared, and melt temperature reduces 3 DEG C, can play the preferably scattered effect with distribution, color masterbatch pigment It can be well mixed with raw material, coloring effect is good, and the heat-proof polythene tubing presentation quality produced is good, and outer wall is bright wireless Bar, inner wall smooth amixis line, end face is without Appearance quality defects such as stains.

It is described above, only the utility model patent preferred embodiment, but the protection domain of the utility model patent is simultaneously This is not limited to, any one skilled in the art is in the scope disclosed in the utility model patent, according to this Technical scheme and its utility model patent design of utility model patent are subject to equivalent substitution or change, belong to the utility model The protection domain of patent.

Claims (9)

1. a kind of special extrusion screw rod of heat-proof polythene, including feeding section, compression section and screw head, it is characterised in that：Also include First metering section, decompression section, the second metering section and mixing section, the feeding section, compression section, the first metering section, decompression section, second Metering section, mixing section and screw head are sequentially connected, and are adopted on the feeding section, decompression section, the first metering section and the second metering section With one start screw structure；The compression section uses the double thread structure being made up of main thread and added thread, the additional spiral shell Line intersects in feeding section side with main thread, does not intersect in the first metering section side with main thread；The mixing section is using trapezoidal Body structure.

A kind of 2. special extrusion screw rod of heat-proof polythene according to claim 1, it is characterised in that：On the feeding section One start screw structure forms charging spout, and the one start screw structure on first metering section forms the first measuring tank, the decompression One start screw structure in section forms relief groove, and the one start screw structure on second metering section forms the second measuring tank, institute State the double thread structure on compression section and form the solid phase groove being connected with charging spout, and the liquid being connected with the first measuring tank Phase groove.

A kind of 3. special extrusion screw rod of heat-proof polythene according to claim 2, it is characterised in that：The groove of the solid phase groove Bottom land of the bottom along charging spout extends to the bottom land direction of the first measuring tank, and the width of solid phase groove is from feeding section to the first metering section side To gradually decreasing, the solid phase well width in feeding section side is identical with charging well width, the solid phase groove in the first metering section side Width is 0.1~0.2 times of the first metering well width；The bottom land of the liquid phase groove is from the added thread outer surface of feeding section side Extend to the bottom land direction of the first measuring tank, the width of liquid phase groove gradually increases from feeding section to the first metering section direction, added The liquid phase well width for expecting section side is 0.06~0.15 times of charging well width, and the liquid phase well width in the first metering section side is 0.7~0.9 times of first metering well width.

A kind of 4. special extrusion screw rod of heat-proof polythene according to Claims 2 or 3, it is characterised in that：The charging spout Depth and the depth of relief groove be all higher than the depth of the first measuring tank, the depth of second measuring tank is less than the depth of relief groove Degree.

A kind of 5. special extrusion screw rod of heat-proof polythene according to Claims 2 or 3, it is characterised in that：The charging spout Width be less than outer screw diameter, the width of first measuring tank, relief groove and the second measuring tank is all higher than outer screw diameter.

A kind of 6. special extrusion screw rod of heat-proof polythene according to claim any one of 1-3, it is characterised in that：The pressure The external diameter of added thread is smaller 2.5-5mm than the external diameter of main thread in contracting section.

A kind of 7. special extrusion screw rod of heat-proof polythene according to claim any one of 1-3, it is characterised in that：Main thread Helical pitch and added thread helical pitch it is unequal, and the helical pitch of main thread is 1.1~2.1 times of outer screw diameter, added thread Helical pitch is 0.8~1.8 times of outer screw diameter.

A kind of 8. special extrusion screw rod of heat-proof polythene according to claim any one of 1-3, it is characterised in that：It is described mixed The cross sectional shape for closing section is rectangle, and the area of its bottom surface is more than the area of top surface, and the prismatoid structure is by multiple prismatoid groups Into, the spacing between the adjacent prismatoid of any two is identical, multiple prismatoids be divided into upwards in screw shaft it is multiple rows of, each row's Prismatoid annular array on screw rod circumference.

A kind of 9. special extrusion screw rod of heat-proof polythene according to claim any one of 1-3, it is characterised in that：The spiral shell The effective length of bar is 34~40 times of outer screw diameter, and the length of the feeding section is 5~10 times of outer screw diameter, the compression The length of section is 10~21 times of outer screw diameter, and the length of first metering section is 2~6 times of outer screw diameter, the decompression The length of section is 1~5 times of outer screw diameter, and the length of second metering section is 5~11 times of outer screw diameter, the mixing section For 2~8 times of outer screw diameter.