CA1276763C - Screw for single-screw extruder - Google Patents
Screw for single-screw extruderInfo
- Publication number
- CA1276763C CA1276763C CA000506176A CA506176A CA1276763C CA 1276763 C CA1276763 C CA 1276763C CA 000506176 A CA000506176 A CA 000506176A CA 506176 A CA506176 A CA 506176A CA 1276763 C CA1276763 C CA 1276763C
- Authority
- CA
- Canada
- Prior art keywords
- screw
- zone
- compression
- decompression
- pitch angle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/501—Extruder feed section
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/505—Screws
- B29C48/52—Screws with an outer diameter varying along the longitudinal axis, e.g. for obtaining different thread clearance
- B29C48/525—Conical screws
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Dowels (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Screw for a single screw extruder, with a conically shaped feed zone which undergoes transition into a decompression zone which is followed by a compression zone. The compression ratio in the feed zone of the screw is greater than four, with a pitch angle (?1) to the screw line of 15° to 23°, the decompression in the decompression zone amounts to 1.5 to 2.0 and the compression ratio in the compression zone is less than 4.5 with a pitch angle (?2) to the screw line of the screw of 25° to 32°.
Screw for a single screw extruder, with a conically shaped feed zone which undergoes transition into a decompression zone which is followed by a compression zone. The compression ratio in the feed zone of the screw is greater than four, with a pitch angle (?1) to the screw line of 15° to 23°, the decompression in the decompression zone amounts to 1.5 to 2.0 and the compression ratio in the compression zone is less than 4.5 with a pitch angle (?2) to the screw line of the screw of 25° to 32°.
Description
~ ;~ 7~7~3 The invention relates to a screw for a single screw extruder with a conically shaped feed zone which undergoes transition into a decompression zone which is followed by a compression zone.
Such screws are used for the extrusion processing of pulverous, highly dispersed or granulated polymer materials with large bulk volumes.
There is already known a screw for a single screw extruder with a conically shaped feed zone or entry zone and a cylindrical compression zone in which the pitch angle of its screw line is constant.
Furthermore a screw for a single screw extruder is known which has a decompression zone which is arranged in the compression zone. With this, the pitch angle of the screw line is constant and lies within the limits of 17 to 27, the compression ratio along the screw is likewise constant and lies between 1.5 and 5.
Disadvantageous with the known screws is the small diameter of the screw core at the beginning of the feed zone, where the forces are greatest and where there occurs most frequently a fracturing of the screw, the loss of compression off-centre of the feed region to the screw and the outer cylinder belonging to it, the failure of a decompression zone or compression relief zone at the beginning of the compression zone which is necessary for the deaeration of the moulding composition, the non-optimal pitch angle of the worm screw line and the compression ratio in the feeding and compression zone, so that the productivity is small, the difficult removal of the screw from the outer cylinder and the fact that they are not suitable for the direct processing of pulverous materials wi1:hout prior granulation.
The object underlying the invention consists therefore in so constructing the screw of the initially ~4~
7~3 indicated type that error free large yields can be produced with high productivity, with maintenance of a rapid and simple disassembly and with direct feeding with pulverous material without pre-granulation.
According to the present invention, there is provided a screw for a single screw extruder, with a conically shaped feed zone which undergoes transition into a decompression zone which is followed by a compression zone, characterised in that the compression ratio in the feed zone of the screw is greater than four, with a pitch angle to the screw line of 15 to 23, the decompression in the decompression zone amounts to 1.5 to 2.0 and the compression ratio in the compression zone is less than 4.5 with a pitch angle to the screw line of the screw of 25 to 32.
The compression zone of the screw may be cylindrical, or it may be conically tapered in its forward region.
With the screw according to the invention, the smallest pitch angle to the screw line of the screw is l`ocated in the feed region of the extruder. On rotation of the screw, this makes possible, the ready uptake of pulverous highly dispersed and other materials with large bulk volumes. Since the compression ratio of the screw is large in the feed zone, a high degree of compaction and a high degree of the degasification of the material are achievable. The largest pitch angle to the screw line of the screw is in the exit zone, as a result of which a maximum productivity of the extruder is guaranteed and products with large cross-section can be produced. The provision of a decompression zone and possibly a vacuum zone makes possible a separation of air, moisture and other fluid substances contained in the material or separated off in the processsing. Furthermore, the working volume of the screw duct of the screw can get bigger in the feed zone of 1 27~
the extruder, corresponding to the bulk volume of the material being worked. ln this way, the compression ratio of the screw may be varied in the compression zone of the S extruder in dependence on the variation in the specific volume of the material on melting and the desired degree of additional homogenisation as a result of production of the differential return flow.
The disassembly of the screw from the outer cylinder is capable of being carried out quickly and effectively, which is especially important in the case of the possible thermosetting three-dimensional cross-linking of the moulding composition during the extruding. Finally, the shearing forces and correspondingly the residence time of the material in the extruder can be regulated within wide limits which is of especial significance in the processing of thermostable polymer moulding compositions.
Preferred embodiments of the invention are explained hereinafter as examples without limitative manner, having reference to the attached drawings, wherein:
Figure l shows a first constructional form of the screw, and Figure 2 shows a second constructional form of the screw.
The screw 2 for single screw extruders shown in Figures 1 and 2 has a conically shaped feed zone I, a decompression zone II connecting thereto and a compression zone III following thereon. The compression ratio in the feed zone I is, with a pitch angle '~l to the screw line of the screw 2 of 15 to 23, greater than four. The compression release in the decompression zone II amounts to 1.5 to 2Ø The degree of compression in the compression zone II is less than 4.5 with a pitch angle '~2 to the screw line of the screw 2 of 25 to 32.
lZ7~763 The compression ratio in the feed zone I forming the first region of the screw is determined by the larger diameter of the screw 2 and the larger duct depth at the beginning of the feed zone I in comparison with the diameter of the screw 2 and the duct depth at the end of the feed zone I.
The second region of the screw 2 is formed by the decompression zone II, a transition zone and the compression zone III. It has an essentially smaller variation in diameter which remains unaltered in the case of a cylindrical compression zone III. In the decompression zone II, the depth of the screw channel is greater. The decompression zone II can be connected with opening 4 in the outer cylinder 3 for the drawing off of gaseous products carried forward in the feeding or separated off in the working. The compression ratio in the compression zone III amounts to 1.5 to 4.5 and extends, with the working of hard polyvinylchloride, to from 2.7 to 3.1, with soft polyvinylchloride to from 3.0 to 3.5, with high density polyethylene from 3.70 to 4.35, with low density polyethylene to from 4.00 to 4.50, with polypropylene to from 3.70 to 4.35, with polyamide and, polystyrene to from 4.00 to 4.35. A storage chamber 1 is arranged at the beginning of the outer cylinder 3.
In the embodiment shown in Figure 1, the compression zone III is cylindrical, being shown conically in Figure 2.
The operation of the single screw extruder according to the invention is as follows:
The polymer material is fed into the feed zone I
from the chamber 1. Resulting from the rotation of the screw 2 in the outer cylinder 3, the screw web takes up the polymer material from the chamber 1 and conveys it forward into the screw channel of the screw. The polymer material, ~276763 is moreover, compacted as a consequence of the reduction of the duct's cross-section. In the compression zone II, the air carried forward from the polymer material, the moisture and other gaseous products are separated off, after which the polymer material, as a result of the rotation of the screw, is compressed and homogenised and then is pressed out to the shaping tool at the end of the outer cylinder 3.
Such screws are used for the extrusion processing of pulverous, highly dispersed or granulated polymer materials with large bulk volumes.
There is already known a screw for a single screw extruder with a conically shaped feed zone or entry zone and a cylindrical compression zone in which the pitch angle of its screw line is constant.
Furthermore a screw for a single screw extruder is known which has a decompression zone which is arranged in the compression zone. With this, the pitch angle of the screw line is constant and lies within the limits of 17 to 27, the compression ratio along the screw is likewise constant and lies between 1.5 and 5.
Disadvantageous with the known screws is the small diameter of the screw core at the beginning of the feed zone, where the forces are greatest and where there occurs most frequently a fracturing of the screw, the loss of compression off-centre of the feed region to the screw and the outer cylinder belonging to it, the failure of a decompression zone or compression relief zone at the beginning of the compression zone which is necessary for the deaeration of the moulding composition, the non-optimal pitch angle of the worm screw line and the compression ratio in the feeding and compression zone, so that the productivity is small, the difficult removal of the screw from the outer cylinder and the fact that they are not suitable for the direct processing of pulverous materials wi1:hout prior granulation.
The object underlying the invention consists therefore in so constructing the screw of the initially ~4~
7~3 indicated type that error free large yields can be produced with high productivity, with maintenance of a rapid and simple disassembly and with direct feeding with pulverous material without pre-granulation.
According to the present invention, there is provided a screw for a single screw extruder, with a conically shaped feed zone which undergoes transition into a decompression zone which is followed by a compression zone, characterised in that the compression ratio in the feed zone of the screw is greater than four, with a pitch angle to the screw line of 15 to 23, the decompression in the decompression zone amounts to 1.5 to 2.0 and the compression ratio in the compression zone is less than 4.5 with a pitch angle to the screw line of the screw of 25 to 32.
The compression zone of the screw may be cylindrical, or it may be conically tapered in its forward region.
With the screw according to the invention, the smallest pitch angle to the screw line of the screw is l`ocated in the feed region of the extruder. On rotation of the screw, this makes possible, the ready uptake of pulverous highly dispersed and other materials with large bulk volumes. Since the compression ratio of the screw is large in the feed zone, a high degree of compaction and a high degree of the degasification of the material are achievable. The largest pitch angle to the screw line of the screw is in the exit zone, as a result of which a maximum productivity of the extruder is guaranteed and products with large cross-section can be produced. The provision of a decompression zone and possibly a vacuum zone makes possible a separation of air, moisture and other fluid substances contained in the material or separated off in the processsing. Furthermore, the working volume of the screw duct of the screw can get bigger in the feed zone of 1 27~
the extruder, corresponding to the bulk volume of the material being worked. ln this way, the compression ratio of the screw may be varied in the compression zone of the S extruder in dependence on the variation in the specific volume of the material on melting and the desired degree of additional homogenisation as a result of production of the differential return flow.
The disassembly of the screw from the outer cylinder is capable of being carried out quickly and effectively, which is especially important in the case of the possible thermosetting three-dimensional cross-linking of the moulding composition during the extruding. Finally, the shearing forces and correspondingly the residence time of the material in the extruder can be regulated within wide limits which is of especial significance in the processing of thermostable polymer moulding compositions.
Preferred embodiments of the invention are explained hereinafter as examples without limitative manner, having reference to the attached drawings, wherein:
Figure l shows a first constructional form of the screw, and Figure 2 shows a second constructional form of the screw.
The screw 2 for single screw extruders shown in Figures 1 and 2 has a conically shaped feed zone I, a decompression zone II connecting thereto and a compression zone III following thereon. The compression ratio in the feed zone I is, with a pitch angle '~l to the screw line of the screw 2 of 15 to 23, greater than four. The compression release in the decompression zone II amounts to 1.5 to 2Ø The degree of compression in the compression zone II is less than 4.5 with a pitch angle '~2 to the screw line of the screw 2 of 25 to 32.
lZ7~763 The compression ratio in the feed zone I forming the first region of the screw is determined by the larger diameter of the screw 2 and the larger duct depth at the beginning of the feed zone I in comparison with the diameter of the screw 2 and the duct depth at the end of the feed zone I.
The second region of the screw 2 is formed by the decompression zone II, a transition zone and the compression zone III. It has an essentially smaller variation in diameter which remains unaltered in the case of a cylindrical compression zone III. In the decompression zone II, the depth of the screw channel is greater. The decompression zone II can be connected with opening 4 in the outer cylinder 3 for the drawing off of gaseous products carried forward in the feeding or separated off in the working. The compression ratio in the compression zone III amounts to 1.5 to 4.5 and extends, with the working of hard polyvinylchloride, to from 2.7 to 3.1, with soft polyvinylchloride to from 3.0 to 3.5, with high density polyethylene from 3.70 to 4.35, with low density polyethylene to from 4.00 to 4.50, with polypropylene to from 3.70 to 4.35, with polyamide and, polystyrene to from 4.00 to 4.35. A storage chamber 1 is arranged at the beginning of the outer cylinder 3.
In the embodiment shown in Figure 1, the compression zone III is cylindrical, being shown conically in Figure 2.
The operation of the single screw extruder according to the invention is as follows:
The polymer material is fed into the feed zone I
from the chamber 1. Resulting from the rotation of the screw 2 in the outer cylinder 3, the screw web takes up the polymer material from the chamber 1 and conveys it forward into the screw channel of the screw. The polymer material, ~276763 is moreover, compacted as a consequence of the reduction of the duct's cross-section. In the compression zone II, the air carried forward from the polymer material, the moisture and other gaseous products are separated off, after which the polymer material, as a result of the rotation of the screw, is compressed and homogenised and then is pressed out to the shaping tool at the end of the outer cylinder 3.
Claims (3)
1. Screw for a single screw extruder, with a conically shaped feed zone (I) which undergoes transition into a decompression zone (II) which is followed by a compression zone (III), characterised in that the compression ratio in the feed zone (I) of the screw is greater than four, with a pitch angle (?1) to the screw line of 15° to 23°, that the decompression in the decompression zone (II) amounts to 1.5 to 2.0 and the compression ratio in the compression zone (III) is less than 4.5 with a pitch angle (?2) to the screw line of the screw of 25° to 32°.
2. Screw according to claim 1, characterised in that the compression zone (III) of the screw is cylindrical.
3. Screw according to claim 1, characterised in that the compression zone (III) of the screw is conically tapered in its forward region.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BG8569680A BG41536A1 (en) | 1985-04-10 | 1985-04-10 | Worm for mono- worm extruder |
| BG69680 | 1985-04-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1276763C true CA1276763C (en) | 1990-11-27 |
Family
ID=3915431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000506176A Expired - Lifetime CA1276763C (en) | 1985-04-10 | 1986-04-09 | Screw for single-screw extruder |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP0197550B1 (en) |
| JP (1) | JPS621520A (en) |
| BG (1) | BG41536A1 (en) |
| CA (1) | CA1276763C (en) |
| CS (1) | CS237386A1 (en) |
| DE (1) | DE3668277D1 (en) |
| FI (1) | FI861438A (en) |
| HU (1) | HUT40945A (en) |
| IN (1) | IN167243B (en) |
| NO (1) | NO861376L (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3051420B2 (en) * | 1990-03-02 | 2000-06-12 | 株式会社日立製作所 | Air conditioner and method of manufacturing indoor heat exchanger used for the device |
| US5662415A (en) * | 1996-01-19 | 1997-09-02 | Gisco Technology | Conveyor for degassing of mixtures for solid surface products and method of use |
| JP4354108B2 (en) * | 2000-11-10 | 2009-10-28 | 株式会社星プラスチツク | Screw for resin extruder |
| AT503362B1 (en) * | 2005-10-24 | 2013-12-15 | Theysohn Extrusionstechnik Ges M B H | SCREW |
| RU2520463C2 (en) * | 2010-03-16 | 2014-06-27 | Павло СЕМЕНИВСКИЙ | Method of extruder for production of closed-section beam elements, mainly, tubular beams and closed-section beam element thus produced |
| CN110901016B (en) * | 2019-11-04 | 2021-09-03 | 大维塑料技术(南京)有限公司 | Screw rod of plastic extruding machine |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2076728A (en) * | 1980-05-21 | 1981-12-09 | Midland Ross Corp | Extrusion devices and methods of reclaiming scrap plastic material |
-
1985
- 1985-04-10 BG BG8569680A patent/BG41536A1/en unknown
-
1986
- 1986-04-03 CS CS862373A patent/CS237386A1/en unknown
- 1986-04-03 FI FI861438A patent/FI861438A/en not_active Application Discontinuation
- 1986-04-04 IN IN250/MAS/86A patent/IN167243B/en unknown
- 1986-04-08 DE DE8686104812T patent/DE3668277D1/en not_active Expired - Fee Related
- 1986-04-08 EP EP86104812A patent/EP0197550B1/en not_active Expired - Lifetime
- 1986-04-09 CA CA000506176A patent/CA1276763C/en not_active Expired - Lifetime
- 1986-04-09 NO NO861376A patent/NO861376L/en unknown
- 1986-04-09 JP JP61081960A patent/JPS621520A/en active Pending
- 1986-04-10 HU HU861518A patent/HUT40945A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| HUT40945A (en) | 1987-03-30 |
| FI861438A0 (en) | 1986-04-03 |
| FI861438A (en) | 1986-10-11 |
| DE3668277D1 (en) | 1990-02-22 |
| EP0197550A2 (en) | 1986-10-15 |
| EP0197550A3 (en) | 1988-10-05 |
| NO861376L (en) | 1986-10-13 |
| EP0197550B1 (en) | 1990-01-17 |
| CS237386A1 (en) | 1989-06-13 |
| JPS621520A (en) | 1987-01-07 |
| IN167243B (en) | 1990-09-29 |
| BG41536A1 (en) | 1987-07-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 19930529 |