CA1128271A - Apparatus and a process for processing inhomogeneous rubber mixtures - Google Patents
Apparatus and a process for processing inhomogeneous rubber mixturesInfo
- Publication number
- CA1128271A CA1128271A CA314,593A CA314593A CA1128271A CA 1128271 A CA1128271 A CA 1128271A CA 314593 A CA314593 A CA 314593A CA 1128271 A CA1128271 A CA 1128271A
- Authority
- CA
- Canada
- Prior art keywords
- screw
- rubber mixtures
- extrusion
- inhomogeneous
- mixture
- 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
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 26
- 239000005060 rubber Substances 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 7
- 238000001125 extrusion Methods 0.000 claims abstract description 10
- 238000010008 shearing Methods 0.000 claims abstract description 10
- 239000011324 bead Substances 0.000 claims abstract description 5
- 239000000470 constituent Substances 0.000 claims abstract description 5
- 238000001746 injection moulding Methods 0.000 claims abstract description 5
- 239000004033 plastic Substances 0.000 claims abstract description 5
- 238000004519 manufacturing process Methods 0.000 claims abstract description 3
- 238000000465 moulding Methods 0.000 claims abstract description 3
- 239000002245 particle Substances 0.000 claims abstract description 3
- 230000002250 progressing effect Effects 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 230000007423 decrease Effects 0.000 claims description 2
- 238000010276 construction Methods 0.000 abstract 1
- 239000000654 additive Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 239000004971 Cross linker Substances 0.000 description 1
- 239000006057 Non-nutritive feed additive Substances 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000011345 viscous material Substances 0.000 description 1
- 238000004073 vulcanization Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
- B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
- B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
- B29B7/40—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft
- B29B7/42—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft with screw or helix
- B29B7/428—Parts or accessories, e.g. casings, feeding or discharging means
- B29B7/429—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
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)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
AN APPARATUS AND A PROCESS FOR PROCESSING
INHOMOGENEOUS RUBBER MIXTURES
Abstract of the Disclosure A process for the production of homogeneous compact mouldings from vulcanisable inhomogeneous rubber mixture by extrusion or injection moulding, characterised in that the inhomogeneous rubber mixture is forced to form a progressing, continuously rotating bead within a screw channel of the extrusion screw by all the constituents of the mixture being compressed and forcibly separated from one another again, and is subsequently converted into a homogeneous plastic mass on passing through a shearing gap in which the individual particles lose their structure and an extrusion screw construction for carrying out the process.
Le A 18 524
INHOMOGENEOUS RUBBER MIXTURES
Abstract of the Disclosure A process for the production of homogeneous compact mouldings from vulcanisable inhomogeneous rubber mixture by extrusion or injection moulding, characterised in that the inhomogeneous rubber mixture is forced to form a progressing, continuously rotating bead within a screw channel of the extrusion screw by all the constituents of the mixture being compressed and forcibly separated from one another again, and is subsequently converted into a homogeneous plastic mass on passing through a shearing gap in which the individual particles lose their structure and an extrusion screw construction for carrying out the process.
Le A 18 524
Description
~8Z7~
Quality requirements in -technical rubber articles become more stringent and, simultaneously, the cycle times in processing rubber mixtures by injection moulding have -to be shortened to increase output and to improve economics.
Attempts have been made to produce technical rubber articles simpler, less expensive and with less energy consump-tion by using powder-form "rubber mixtures" in strip or granular form instead of completely homogeneous rubber mixtures.
"Rubber mixtures" contain the unvulcanised rubber and all the additives such as fillers (carbon black or silicates), plasticiser oils, vulcanisation agents (cross-linkers), additives (antiagers, antiozonants or stabilisers) and processing aids. They are processed simply by shaping and vulcanising. To produce rubber mixtures the generally very tough constituents have to be intensively mixed in internal mixers or on mixing rolls with a high consumption of energy in either case, Powder-form rubber mixtures are, however, easy to produce because only powder-form cons-tituents starting with the powder-form rubber have to be mixed with plasticiser oils, provided, the necessary specially developed mixing units are avilable.
Powder-form rubber mixtures are normally compacted Le A 18 524 - 2 -.~ ~
~f~8Z7~
and homogenised before processing by extrusion or injection moulding. This can be done in apparatus specially developed for this purpose.
The present invention relates to screw extruders for processing rubber which, in addition to their normal delivering and compacting efect, also mix, exert a shearing ef~ect and homogenise. These extruders are suit-able for processing powder-form rubber mixtures directly, i.e. without inter-mediate compacting.
The present invention provides a screw extruder for processing inhomogeneous rubber mixtures, comprising at least one mixing and shearing section in which the depth of the screw channels, measured in a direction transverse to the screw, increases gradually and continuously from almost zero and suddenly decreases again to almost zero, resulting in the formation of a "chamber" in which the material being processed is set rotating.
The present invention also relates to a process for the production of homogeneous, compact mouldings from vulcanisable, inhomogeneous rubber mixtures by extrusion or injection moulding, in which the inhomogeneous rub-ber mixture is forced to form a progressing, continuously rotating bead within a screw channel of an extrusion screw in which the constituents of the mixture are compressed and forcibly separated from one another again, and wherein the rubber mixture is subsequently converted into a homogeneous plastic mass on passing through a shearing gap in which ~h~ individual parti-cles lose their structure.
The principle of the extrusion screw used in the extruder according to the invention is shown in Figures 1 ~diagrammatic view) and 2 (cross-section). The housing of the screw machine is denoted by the reference 4.
The reference 3 denotes the screw land which extends as near as possible to the housing wall. The reference 1 denotes the body of the screw. When it rota~es in the direction of the arrow (Figure 2), this screw delivers partly a powder form material and partly a plastic viscous material.
`" 9.~LZ~
The depth of the screw chanrlel is variable in the lntermediate space bctween -two screw lands. At Z th~ depth of the screw charlllcl is very smal~ so -tha-t u natrow s~lea-ring gup is ; for~c~a. Thereafter, -the channel (!ept}1 increases g-raduaLly and continuously llntil~ just before -the next s~learing gap
Quality requirements in -technical rubber articles become more stringent and, simultaneously, the cycle times in processing rubber mixtures by injection moulding have -to be shortened to increase output and to improve economics.
Attempts have been made to produce technical rubber articles simpler, less expensive and with less energy consump-tion by using powder-form "rubber mixtures" in strip or granular form instead of completely homogeneous rubber mixtures.
"Rubber mixtures" contain the unvulcanised rubber and all the additives such as fillers (carbon black or silicates), plasticiser oils, vulcanisation agents (cross-linkers), additives (antiagers, antiozonants or stabilisers) and processing aids. They are processed simply by shaping and vulcanising. To produce rubber mixtures the generally very tough constituents have to be intensively mixed in internal mixers or on mixing rolls with a high consumption of energy in either case, Powder-form rubber mixtures are, however, easy to produce because only powder-form cons-tituents starting with the powder-form rubber have to be mixed with plasticiser oils, provided, the necessary specially developed mixing units are avilable.
Powder-form rubber mixtures are normally compacted Le A 18 524 - 2 -.~ ~
~f~8Z7~
and homogenised before processing by extrusion or injection moulding. This can be done in apparatus specially developed for this purpose.
The present invention relates to screw extruders for processing rubber which, in addition to their normal delivering and compacting efect, also mix, exert a shearing ef~ect and homogenise. These extruders are suit-able for processing powder-form rubber mixtures directly, i.e. without inter-mediate compacting.
The present invention provides a screw extruder for processing inhomogeneous rubber mixtures, comprising at least one mixing and shearing section in which the depth of the screw channels, measured in a direction transverse to the screw, increases gradually and continuously from almost zero and suddenly decreases again to almost zero, resulting in the formation of a "chamber" in which the material being processed is set rotating.
The present invention also relates to a process for the production of homogeneous, compact mouldings from vulcanisable, inhomogeneous rubber mixtures by extrusion or injection moulding, in which the inhomogeneous rub-ber mixture is forced to form a progressing, continuously rotating bead within a screw channel of an extrusion screw in which the constituents of the mixture are compressed and forcibly separated from one another again, and wherein the rubber mixture is subsequently converted into a homogeneous plastic mass on passing through a shearing gap in which ~h~ individual parti-cles lose their structure.
The principle of the extrusion screw used in the extruder according to the invention is shown in Figures 1 ~diagrammatic view) and 2 (cross-section). The housing of the screw machine is denoted by the reference 4.
The reference 3 denotes the screw land which extends as near as possible to the housing wall. The reference 1 denotes the body of the screw. When it rota~es in the direction of the arrow (Figure 2), this screw delivers partly a powder form material and partly a plastic viscous material.
`" 9.~LZ~
The depth of the screw chanrlel is variable in the lntermediate space bctween -two screw lands. At Z th~ depth of the screw charlllcl is very smal~ so -tha-t u natrow s~lea-ring gup is ; for~c~a. Thereafter, -the channel (!ept}1 increases g-raduaLly and continuously llntil~ just before -the next s~learing gap
2' it suddenly clecrcases again so that a sharp edge is formed in flont of the gap. In Fig. 2 , three such "chambers" are provided per screw channel. Although this has proved -to be best, it is also possible to provide one, two or more chambers.
A partly powder-form, partly plastic material, which is situated in the rotating screw, is initially offered a space in which it is set rotating, as shown at 5, by the rotation of the screw. The conditions are similar to those prevailing in the bead which is formed in front of the gap of mixing rolls. Thereafter, the material has to pass through the gap 2' where it is e~posed to intense shear forces. In the example of Figures l and 2, this process is repeated $wice for each revolution of the screw.
The screw does not have to be and, in general, is not constructed in the manner described above over i$s entire length. In general, a feed zone is present at its beginning; in other words~ this feed section and the surrounding screw housing are designed in such a way that powder-form or inhomogeneous s-trip material can be received.
The feed zone is usually followed by a delivery zone and then by a mixing zoneS as described above. This mixing Le A l8 524 - 4 ~
1iL23~Z7~
zone may in turn be followed by ano-ther delivery ~one, anothcr mix:ing zone such as de.scribe(l above and, fLn~lly, by a discharge zone desigrled to build llp pressure.
The pitch of the screw lands ol th~ mixin~
section may by made variable according to -the diame-ter of the screw. The shearing gap between the barrel sleeve and -the screw channel may be from O.Ol to lO mm wide and the width of the shearillg flight land may be from l.0 to 20 mm.
The channel depth between two shearing lands extends in an arbitrary convex curve 6 from the shearing gap ~ to the point of reversal and terminates in an arbi-trary concave curve 7 which runs into the next shearing flight edge.
Practical tests were carried out in the mixing section described above using a typical extrusion mixture which is intended to be representa-tive o-f the whole range of mixtures used in the rubber industry. The screw used, complete with mixing section, had a diameter of 90 mm and a length of preferably from 16 to 24 D.
Le A 18 524 - 5 -
A partly powder-form, partly plastic material, which is situated in the rotating screw, is initially offered a space in which it is set rotating, as shown at 5, by the rotation of the screw. The conditions are similar to those prevailing in the bead which is formed in front of the gap of mixing rolls. Thereafter, the material has to pass through the gap 2' where it is e~posed to intense shear forces. In the example of Figures l and 2, this process is repeated $wice for each revolution of the screw.
The screw does not have to be and, in general, is not constructed in the manner described above over i$s entire length. In general, a feed zone is present at its beginning; in other words~ this feed section and the surrounding screw housing are designed in such a way that powder-form or inhomogeneous s-trip material can be received.
The feed zone is usually followed by a delivery zone and then by a mixing zoneS as described above. This mixing Le A l8 524 - 4 ~
1iL23~Z7~
zone may in turn be followed by ano-ther delivery ~one, anothcr mix:ing zone such as de.scribe(l above and, fLn~lly, by a discharge zone desigrled to build llp pressure.
The pitch of the screw lands ol th~ mixin~
section may by made variable according to -the diame-ter of the screw. The shearing gap between the barrel sleeve and -the screw channel may be from O.Ol to lO mm wide and the width of the shearillg flight land may be from l.0 to 20 mm.
The channel depth between two shearing lands extends in an arbitrary convex curve 6 from the shearing gap ~ to the point of reversal and terminates in an arbi-trary concave curve 7 which runs into the next shearing flight edge.
Practical tests were carried out in the mixing section described above using a typical extrusion mixture which is intended to be representa-tive o-f the whole range of mixtures used in the rubber industry. The screw used, complete with mixing section, had a diameter of 90 mm and a length of preferably from 16 to 24 D.
Le A 18 524 - 5 -
Claims (2)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A screw extruder for processing inhomogeneous rubber mixtures, com-prising at least one mixing and shearing section in which the depth of the screw channels, measured in a direction transverse to the screw, increases gradually and continuously from almost zero and suddenly decreases again to almost zero, resulting in the formation of a "chamber" in which the material being processed is set rotating.
2. A process for the production of homogeneous compact mouldings from vulcanisable inhomogeneous rubber mixtures by extrusion or injection moulding, which comprises forcing the inhomogeneous rubber mixture to form a progress-ing, continuously rotating bead within a screw channel of an extrusion screw by all the constituents of the mixture being compressed and forcibly separated from one another again, and subsequently converting the bead into a homo-geneous plastic mass on passing through a shearing gap in which individual particles lose their structure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2748717.8 | 1977-10-29 | ||
| DE19772748717 DE2748717A1 (en) | 1977-10-29 | 1977-10-29 | DEVICE AND METHOD FOR PROCESSING INHOMOGENIC RUBBER MIXTURES |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1128271A true CA1128271A (en) | 1982-07-27 |
Family
ID=6022666
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA314,593A Expired CA1128271A (en) | 1977-10-29 | 1978-10-27 | Apparatus and a process for processing inhomogeneous rubber mixtures |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0001784B1 (en) |
| JP (1) | JPS5471177A (en) |
| CA (1) | CA1128271A (en) |
| DE (2) | DE2748717A1 (en) |
| ES (1) | ES245906Y (en) |
| IT (1) | IT7851672A0 (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2496625A (en) * | 1946-11-13 | 1950-02-07 | Western Electric Co | Apparatus for advancing and working plastic materials |
| CH305212A (en) * | 1952-03-06 | 1955-02-15 | Wilhelm Dr Ludowici | Screw press for plastic material. |
| DE1091841B (en) * | 1956-08-23 | 1960-10-27 | Buss Ag | Mixing and kneading device |
| BE606868A (en) * | 1960-08-10 | 1900-01-01 | ||
| US3897937A (en) * | 1973-08-30 | 1975-08-05 | A Paul Limbach | Extruder screw |
-
1977
- 1977-10-29 DE DE19772748717 patent/DE2748717A1/en not_active Withdrawn
-
1978
- 1978-10-18 EP EP78101171A patent/EP0001784B1/en not_active Expired
- 1978-10-18 DE DE7878101171T patent/DE2860626D1/en not_active Expired
- 1978-10-27 CA CA314,593A patent/CA1128271A/en not_active Expired
- 1978-10-27 JP JP13174378A patent/JPS5471177A/en active Pending
- 1978-10-27 ES ES1978245906U patent/ES245906Y/en not_active Expired
- 1978-10-27 IT IT7851672A patent/IT7851672A0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ES245906Y (en) | 1980-11-01 |
| DE2860626D1 (en) | 1981-05-07 |
| IT7851672A0 (en) | 1978-10-27 |
| DE2748717A1 (en) | 1979-05-10 |
| EP0001784A1 (en) | 1979-05-16 |
| EP0001784B1 (en) | 1981-04-15 |
| ES245906U (en) | 1980-04-01 |
| JPS5471177A (en) | 1979-06-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 19990727 |