CN2126515Y

CN2126515Y - Wave-like high effective injection screw stem

Info

Publication number: CN2126515Y
Application number: CN 92228447
Authority: CN
Inventors: 王兴天; 杨于光
Original assignee: BEIJING COLLEGE OF CHEMICAL TECHNOLOGY
Current assignee: BEIJING COLLEGE OF CHEMICAL TECHNOLOGY; Beijing University of Chemical Technology
Priority date: 1992-07-25
Filing date: 1992-07-25
Publication date: 1993-01-06
Anticipated expiration: 2002-07-25

Abstract

The utility model relates to a wave-like high effective injection screw stem. The main body part of the wave-like high effective injection screw stem is composed of a conveying segment L1, a wave-like plasticizing segment L2, and a homogenizing segment L3 with dual wave bands and short band length, wherein, the front part of the main body is connected with a thread screw stem head which is sheathed with a non-return ring, and each screw pitch of the plasticizing segment L2 has a wave crest and a wave trough. When materials enter the wave crest in company with the roatation of the screw stem, the materials are strongly sheared and compressed. However, in company with the rotation of the screw stem, the partial materials fall into a wave trough with larger volume; so that the volume of the materials is expanded, and the heat is released out. Thereby, the purpose of low-temperature plasticization is achieved, and the heat decomposition of the materials is prevented. Thus, the utility model is particularly suitable for processing unplasticised polyvinyl chloride or other materials with poor heat stability, etc.

Description

Wave-like high effective injection screw stem

The utility model relates to a kind of plastic processing machinery, particularly a kind of wavy efficient injection screw that is applied on the plastic-injection moulding machine.

Injection screw is the critical component of injection (mo(u)lding) machine, and the correctness that its structural design and optimization of geometric parameters are selected directly has influence on the quality quality of injection molded article and the height of output, and is related to the accommodation of injector to different material.The basic structure of present conventional injection screw as shown in Figure 1, this screw rod is made of screw rod main part 1 and screw head 2, the main part of screw rod 1 is divided into feeding section L again ₁, compression section L ₂With metering section L ₃, three sections sums are generally 18D, and wherein D is the screw rod external diameter, and three sections sums are called L.It each section segment length distributes is: L ₁=8D, L ₂=6D, L ₃=4D, the pitch t=D of screw rod, bosom screw channel groove depth is h ₁=0.12D, compression ratio h ₁/ h ₃=2.5.h ₃Be the most shallow place of screw rod screw channel groove depth.The conveying of the conventional screw of this old syllogic and plasticizing mechanism mainly are to be undertaken by friction and internal shear effect between material and screw rod, machine barrel, the spiro rod plasticizing process will be occupied an leading position gradually from the energy of shear heat, and external heat will account for secondary status, and shear heat depends primarily on factors such as the physical property of the shape of screw channel and each section physical dimension and material and rheological property.When solid material is brought L into from the material mouthful screw rod that adding is rotated ₁Realize Solid Conveying and Melting in the dark screw channel of section, enter into the L that screw channel shoals gradually then ₂Be compressed plasticizing in the section, enter the L of dark screw channels such as having again ₃Section is subjected to the further strong homogenization of shearing, and flows into screw front end at last, waits for next time being injected into mold cavity in the injection process.

The problem that this conventional three-stage screw exists have following some:

First: because the L of this screw rod ₃Section is longer, makes L ₂And L ₁Segment length shortens relatively, and the thermal history of material in screw channel is restricted, and makes to enter into L ₂The material of section is difficult to complete fusion, promptly can't normally enter into the more shallow L of screw channel ₃In the section, so just produce material by the asphyxia by external pressure on the chest and abdomen phenomenon, cause the rising of screw axial pressure and moment of torsion, the screw rod overload maybe can't be rotated, therefore, have to take the slow-speed of revolution to remedy the pile-up phenomenon of material, make screw rod under high rotating speed, not work, have a strong impact on the raising of production capacity with the way of time of staying of prolonging material.

Second: because L ₃The existence of section shallow screw channel section, when material at L ₂And L ₁After the effect that is rubbed continuously and shear, again at L ₃Section is subjected to more violent shear action, has caused the bulk deposition of energy, and temperature of charge is risen, for the materials such as hard vinyl chloride of thermostability difference, be easy to therefore produce thermal decomposition, cause the carbonization of material, and produce poison gas, injection can't be carried out.

Three, present, people attempt to adopt the way of the structure that reduces rotating speed and cancellation band check ring screw head to reduce thermal decomposition and the pile-up material problem that shear heat causes, but when the hard vinyl chloride the part with complicated structure of processing, owing to runner and the complicated increase that causes the die cavity resistance of die cavity, and then the very big back-pressure of generation refluxes, can't guarantee high filled film pressure, so can't mold qualified UPVC goods, this also can't use the reason place of UPVC moulding the part with complicated structure just up to now.

The purpose of this utility model just is to overcome the above-mentioned shortcoming and defect of existing in prior technology, and provide a kind of with wavy spiro rod plasticizing section, the high productive capacity of the threaded screw head of check ring be housed, do not produce thermal decomposition, be applicable to the wavy efficient injection screw of processing UPVC the part with complicated structure.

The purpose of this utility model is to realize that by following technical scheme the main part of screw rod is by transportation section L ₁, fluxing zone L with contoured shape ₂The very short homogenizing zone L with having two waveband and segment length ₃Constitute, the front portion of screw rod main body is connected with the threaded screw head that is set with check ring, at fluxing zone L ₂Each pitch in a crest and trough are all arranged, when material along with screw rod rotate into the crest place time, then be subjected to strong the shearing and extruding, but rotation along with screw rod, this partial material falls into the trough with big volume again, makes the bulk and heat of volume of material be released out, has reached the purpose of low-temperature plasticizing, prevented the thermal decomposition of material, so be particularly suitable for processing the material of thermostability differences such as UPVC.

Therefore: remarkable result of the present utility model is:

1, the fluxing zone L that has wavy screw channel ₂Setting, not only can finish the shearing of material plasticizing, and have the effect that makes the loose cooling of material, can prevent the thermal decomposition of material effectively, be particularly suitable for processing the UPVC material of thermal sensitivity difference.

2, the short homogenizing zone L that has two waveband ₃Setting, can make the material of fusion before injection, obtain further homogenizing, positive effect is arranged improving the quality of products.

3, the setting of threaded screw head and check ring has the advantages that to stop solution to reflux, and can set up very high cavity pressure, has the characteristics of the goods of forming shape complexity.

Concrete structure of the present utility model is to be realized by following drawings and Examples.

Fig. 1 is the structure chart of existing conventional screw.

Fig. 2 is a structure chart of the present utility model.

Be described in detail below in conjunction with 2 pairs of concrete structures of the present utility model of accompanying drawing:

The utility model is made up of screw rod main paragraph 1 and the screw head 2 that is connected with screw rod main paragraph 1, is transportation section L at main paragraph 1 back segment of screw rod ₁, it is characterized in that: with transportation section L ₁What extend to link to each other is one to have the fluxing zone L of single wavy groove ₂, at fluxing zone L ₂Each pitch t in the radially crest 5 of projection and a radially recessed gradually trough 6 are gradually all arranged, fluxing zone L ₂Leading portion be one to have the homogenizing zone L of double wave shape thread groove ₃, at L ₃Two radially protruding gradually crests 5 and two radially recessed gradually troughs 6 are arranged in each pitch of section, one auxiliary spiral shell rib 4 is arranged between adjacent crest 5 and the trough 6, screw head 2 is provided with screw thread 2A, and movable sleeve is placed with check ring 3 outside the smooth section 2B of screw head 2.Referring to Fig. 2

Architectural feature of the present utility model also is:

The total length L of screw rod main paragraph 1 is 16-18D, transportation section segment length L ₁Be 8-9D, fluxing zone segment length L ₂Be 6D, homogenizing zone segment length L ₃Be 2-3D, pitch t is 0.85-1D, transportation section screw channel groove depth h ₁Be 0.14-0.16D, fluxing zone L ₂With homogenizing zone L ₃Wavy section center line with respect to screw rod main paragraph 1 eccentric distance e is respectively arranged ₂And e ₃, homogenizing zone L ₃Both phase differences of crest 5 and trough 6 be 180 degree.Referring to Fig. 2

Architectural feature of the present utility model also is:

Eccentric distance e ₂Be 0.03-0.05D, eccentric distance e ₃Be 0.015-0.025D, the height of the radially projection of auxiliary spiral shell rib 4 is less than the radially protruding height of screw channel spiral shell rib 1A.Referring to Fig. 2.

Working mechanism of the present utility model is: referring to Fig. 2

Just entered into wavy screw channel enter into second section fluxing zone from first section solid conveying section when material after, the second section screw channel that is unlike in conventional screw again is such, in the screw channel that shoals gradually, be subjected to strong shear action continuously, but be subjected to periodic extruding and shearing.When material is on the crest 5 of screw channel, because the gap between screw channel bottom and the barrel inner surface is very little, at this moment material is subjected to strong extruding and strong the shearing, but rotation along with screw rod, very fast trough 6 places that fall into again of this part material, herein, form bigger space between screw channel bottom surface and the material tube inner wall.At this moment macromolecule is relaxed, and because reducing of pressing in the material, volumetric expansion, and the heat that is stored up by strong shearing is released, and can not make temperature rise excessive and cause the thermal decomposition of material.In addition, owing to the increasing in screw channel space, increased the contact area of material and screw rod, improved radiating condition, its shearing effect of material near low ebb place, screw channel bottom surface is low more, shear heat is also few more, so shear energy has been subjected to control effectively.Screw rod whenever turns around, the material pitch of then advancing, also experience simultaneously crest and trough, this is very useful for the processing UPVC, because too small shearing effect also is disadvantageous to its plasticizing quality, this is determined that by UPVC itself special particle shape and gelling the processing mechanism of UPVC had both required to impose enough shearing forces, but excessive, the time effect that can not apply is long, otherwise will cause the serious thermal decomposition of material.And waveform screw rod described in the utility model just is being suitable for the weak processing mechanism of this tension alternating with relaxation, the last one one.

When melt enters into homogenizing zone L ₃The time, also being unlike in the 3rd section of conventional screw like that, material is in dark section screw channel such as more shallow and long again and continue to be subjected to continuous strong shear action, makes that the temperature rise of material is excessive, so the very easy thermal decomposition that causes material.And melt is in the homogenizing zone of wavy screw rod during homogenizing, be to be in the screw channel of double wave shape, promptly when material when crest 5 is squeezed and shears, some solution can directly be crossed the lower auxiliary spiral shell rib 4 of spiro edge height and laterally flow in the trough 6 that is adjacent, so, melt has been subjected to the further effect of temperature homogenisation and quality homogenizing.Because this moment, shearing effect was subjected to effectively control, just equaled to increase the ratio that temperature control part divides, reached under higher temperature control precision and realized low-temperature plasticizing, make it with decomposition temperature depart from more farther.

Have the adding of check ring 3 and screwed special screw head 2, can eliminate the viscous flow state of molten material at screw head, and can seal the backflow solution, therefore, this screw rod can go out complex-shaped goods at very high model pressure effect compacted under, and this is that present conventional screw is beyond one's reach.

Claims

1, wavy efficient injection screw is made up of screw rod main paragraph 1 and the screw head 2 that is connected with screw rod main paragraph 1, is transportation section L at main paragraph 1 back segment of screw rod ₁, it is characterized in that: with transportation section L ₁What extend to link to each other is one to have the fluxing zone L of single wavy groove ₂, at fluxing zone L ₂Each pitch t in the radially crest 5 of projection and a radially recessed gradually trough 6 are gradually all arranged, fluxing zone L ₂Leading portion be one to have the homogenizing zone L of double wave shape thread groove ₃, at L ₃Two radially protruding gradually crests 5 and two radially recessed gradually troughs 6 are arranged in each pitch of section, one auxiliary spiral shell rib 4 is arranged between adjacent crest 5 and the trough 6, screw head 2 is provided with screw thread 2A, and movable sleeve is placed with check ring 3 outside the smooth section 28 of screw head 2.

2, according to the described wavy efficient injection screw of claim 1, it is characterized in that:

The total length L of screw rod main paragraph 1 is 16-18D, transportation section segment length L ₁Be 8-9D, fluxing zone segment length L ₂Be 6D, homogenizing zone segment length L ₃Be 2-3D, pitch t is 0.85-1D, transportation section screw channel groove depth h ₁Be 0.14-0.16D, fluxing zone L ₂With homogenizing zone L ₃Wavy section center line with respect to screw rod main paragraph 1 eccentric distance e is respectively arranged ₂And e ₃, homogenizing zone L ₃Both phase differences of crest 5 and trough 6 be 180 degree.

3, according to claim 1 or 2 described wavy efficient injection screws, it is characterized in that: eccentric distance e ₂Be 0.03-0.05D, eccentric distance e ₃Be 0.015-0.025D, the height of the radially projection of auxiliary spiral shell rib 4 is less than the radially protruding height of screw channel spiral shell rib 1A.