CN2215400Y

CN2215400Y - Screw rod for plastics extruding machine

Info

Publication number: CN2215400Y
Application number: CN94248351U
Authority: CN
Inventors: 王德臣
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-20
Filing date: 1994-12-20
Publication date: 1995-12-20
Anticipated expiration: 2004-12-20

Abstract

The utility model relates to a screw rod for a plastics extruder which is used for producing blow molding polyvinyl chloride films. A front and a back screws with unequal diameter and unequal distance are arranged on the screw rod. The front screw is started at the D point of the right end of the screw rod, and is ended at the two third point of the length of the screw rod. The back screw is started at the one third point away from the right end of the screw rod, and is ended at the E point of the left end of the screw rod. The length of each screw is the two third of the total length of a screw segment on the screw rod. The utility model has the advantages that the extruder output is higher, the extrusion pressure is high and stable, the good plasticization of PVC materials can be ensured, and the functional requirements of high yield, good plasticization, stable pressure, and energy saving for producing blow molding polyvinyl chloridefilms can be satisfied.

Description

Screw rod for plastics extruding machine

The utility model relates to a kind of screw of plastic extruder that is used for production blowing polyvinyl chloride film.

Shown in Figure 1 be used at present production blowing polyvinyl chloride film plastic extruder a kind of screw rod of generally adopting.This kind screw rod is single head, equidistant screw rod, and its spiral groove depth is to be by deeply gradually shallow setting.Its advantage is: avoided fused materials to stop on screw rod and the drawback that causes PVC to decompose.On the length of screw rod, be divided into three sections, i.e. feeding section, compression section and quantitative section (also being called homogenizing zone) by fill process.No matter the common screw screw diameter size that blowing PVC film uses, quantitatively the spiral groove depth of section is all at 2.2～2.5mm.The spiral groove depth of compression section is to shoal gradually from the feeding section spiral groove depth to transit to quantitative section spiral groove depth, plays compression.The function mechanism of this screw rod is: material enters the feeding section of screw rod from the machine barrel feed opening, material is advanced by the effect promotion material of screw flight helical angle, the machine tube inner wall of the material contact heating of powder shape forms melt film on inwall, scraped by the spiral shell rib of screw rod, enters screw channel.Material enters the compression section extrusion of the air between the powder grain material is fed back into charge door, and with the material compacting.The spiral shell rib scrapes the melt film on the machine tube inner wall continuously, makes the interior solid material of screw channel become the rheid of fusion gradually.Quantitative section of screw rod because the more shallow material to fusion of screw channel carries out homogenizing.The another one effect plays constant displacement pump, quantitatively material is clamp-oned the inflation film mould with certain pressure.Inflation film requires screw rod that three functions are arranged, promptly the output height, material plasticizing is even, extrusion pressure is stable (load is stablized), condition each other again between the three.For improving the then essential screw speed that increases of output, so make material in machine barrel, absorb the time decreased of heat, can also not the solid material package of fusion plastification be contained in and clamp-on blow mold (this cries the Solid Bed fragmentation) in the melting charge together, will occur cloud and mist, silking and the material piece of plasticizing not thus on the film of Sheng Chaning, even the film bubble occur and split production can't be carried out.If will improve screw speed, extrusion capacity is increased, mould inner pressure also increases thereupon, and the single-wormed screw extrusion pressure increases can make extrusion capacity descend, and causes the extrusion pressure instability, few for a long time during the load of die orifice, and the film longitudinal thickness is changed; If increase quantitatively section spiral groove depth, also can improve extrusion capacity, but can cause material seriously to plastify inequality, the extrusion pressure fluctuation is bigger; Reduce the quantitatively spiral groove depth of section, output is descended significantly; Moreover the raising screw speed, because screw channel is more shallow, material is subjected to excessive shearing friction heating to cause material undecomposed in machine barrel, and the screw rod load is increased, power consumption rises.So the production of existing screw rod yields poorly, plasticizing capacity is poor, and the extrusion pressure instability is the existing insurmountable contradiction of itself structure.If use powdery PVC compound, its output is lower.The extruder of screw diameter 90mm, hourly output are no more than 85 kilograms.But produce the polyvinyl chloride inflation film and have to use it again.

The purpose of this utility model provides a kind of four functional requirements of production polyvinyl chloride inflation film of satisfying with regard to being to overcome above-mentioned weak point of the prior art, be the output height, plastify, pressure stability, energy savings, the screw of plastic extruder that is used for production blowing polyvinyl chloride film of novel structure.

The purpose of this utility model can adopt following measure to realize:

The primary structure feature of the screw of plastic extruder that is used for production blowing polyvinyl chloride film of the present utility model is as follows: promptly screw rod is provided with two isometrical, not equidistant forward and backward screw threads; Its preceding thread originates in the right-hand member of screw rod, ends in 2/3rds places of spiro rod length; Rear thread originates in apart from screw rod right-hand member 1/3rd places, ends in the left end of screw rod; The length that is to say two screw threads is 2/3rds of full flight length on the screw rod.

The nominal diameter of the rear thread that processes on the screw of plastic extruder of the present utility model is greater than the nominal diameter of preceding thread; The pitch of rear thread is less than the pitch of preceding thread; In the section that two screw threads intersect, constitute solid phase screw channel G and liquid phase screw channel Y by two screw thread spaces; The groove depth right-to-left of its liquid phase screw channel Y is from-shallow-to-deep, the groove width right-to-left is by narrow gradually wide and be provided with, and the groove depth right-to-left of solid phase screw channel G is by shallow, groove width right-to-left deeply gradually by wide gradually narrow and be provided with.

Nut height H on the utility model screw rod is 5.5～6mm.

Owing on the screw rod of the present utility model two isometrical, not equidistant forward and backward screw threads are set, in the section that two screw threads intersect, constitute solid phase screw channel G and liquid phase screw channel Y by two screw thread spaces; Solid phase screw channel G right-to-left narrows down gradually, by deeply gradually shallow, liquid phase screw channel Y right-to-left broadens gradually, from-shallow-to-deep, the volume of two screw channels is in poised state from right to left basically, on screw rod, form two compression sections of A, B and a quantitative section C, the effect of A section is with the powder compacting, get rid of contained gas between the powder, the effect of B section is that the compression material forces material to pass through gap △ 1, and material absorbs the heat on the extruder barrel inwall and enters in the liquid phase screw channel of C section after shearing, mixing, refinement, fusion by gap △ 1 time; Because C section liquid phase screw channel is dark (than dark 1.3 times of the screw channel of quantitative section of prior art), this just makes fused materials in the liquid phase screw channel can not be subjected to excessive shearing and frictional heat and decomposes, therefore, it has higher extrusion capacity, simultaneously higher and stable extrusion pressure is arranged again, and can guarantee the plasticizing formedness of PVC material.

In addition, screw rod of the present utility model also has all can keep good soffening effect under various rotating speeds, can satisfy and produce four functional requirements of polyvinyl chloride inflation film, promptly the output height, plastify, pressure stability, energy savings; Through evidence: under rotating speed same as the prior art, can improve output 80%, and energy consumption is greatly reduced.

The drawing of accompanying drawing is described as follows:

Fig. 1 is the front view of prior art screw rod.

Fig. 2 is the front view of the utility model screw rod.

The utility model is done with detailed description below with reference to embodiment (accompanying drawing):

As shown in Figure 2, the primary structure feature of the screw of plastic extruder that is used for production blowing polyvinyl chloride film of the present utility model is as follows: promptly screw rod (1) is provided with two isometrical, not equidistant forward and backward screw threads (2) (3); Its preceding thread (2) originates in the right-hand member D place of screw rod, ends in 2/3rds places of spiro rod length; Rear thread (3) originates in apart from screw rod right-hand member 1/3rd places, ends in the left end E place of screw rod; The length that is to say two screw threads is 2/3rds of thread segment total length on the screw rod; The nominal diameter of its rear thread (3) is greater than the nominal diameter of preceding thread (2); The pitch of rear thread (3) is less than the pitch of preceding thread (2); In the section that two screw threads intersect, constitute solid phase screw channel G and liquid phase screw channel Y by two screw thread spaces; The groove depth right-to-left of its liquid phase screw channel Y is from-shallow-to-deep, the groove width right-to-left is by narrow gradually wide and be provided with, and the groove depth right-to-left of solid phase screw channel G is by shallow, groove width right-to-left deeply gradually by wide gradually narrow and be provided with; Nut height H on its screw rod (1) is 5.5～6mm.

Claims

1, a kind of screw of plastic extruder that is used for production blowing polyvinyl chloride film is characterized in that: screw rod (1) is provided with two isometrical, not equidistant forward and backward screw threads (2) (3); Its preceding thread (2) originates in the right-hand member D place of screw rod, ends in 2/3rds places of spiro rod length; Rear thread (3) originates in apart from screw rod right-hand member 1/3rd places, ends in the left end E place of screw rod.

2, screw of plastic extruder according to claim 1 is characterized in that: the nominal diameter of rear thread (3) is greater than the nominal diameter of preceding thread (2); The pitch of rear thread (3) is less than the pitch of preceding thread (2); In the section that two screw threads intersect, constitute solid phase screw channel G and liquid phase screw channel Y by two screw thread spaces; The groove depth right-to-left of its liquid phase screw channel Y is setting from-shallow-to-deep, and the groove depth right-to-left of solid phase screw channel G is by deeply gradually shallow setting.

3, screw of plastic extruder according to claim 1 and 2 is characterized in that: the nut height H on the screw rod (1) is 5.5～6mm.

4, screw of plastic extruder according to claim 2 is characterized in that: solid phase screw channel G right-to-left narrows down gradually, and liquid phase screw channel Y right-to-left broadens gradually.