GB2117311A - Improvements in or relating to a method of and apparatus for extruding elastomeric components - Google Patents

Improvements in or relating to a method of and apparatus for extruding elastomeric components Download PDF

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Publication number
GB2117311A
GB2117311A GB08304328A GB8304328A GB2117311A GB 2117311 A GB2117311 A GB 2117311A GB 08304328 A GB08304328 A GB 08304328A GB 8304328 A GB8304328 A GB 8304328A GB 2117311 A GB2117311 A GB 2117311A
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GB
United Kingdom
Prior art keywords
section
extrudate
cross
predetermined cross
retaining means
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.)
Granted
Application number
GB08304328A
Other versions
GB8304328D0 (en
GB2117311B (en
Inventor
William Lewis Jackson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dunlop Ltd
Original Assignee
Dunlop Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Dunlop Ltd filed Critical Dunlop Ltd
Priority to GB08304328A priority Critical patent/GB2117311B/en
Publication of GB8304328D0 publication Critical patent/GB8304328D0/en
Publication of GB2117311A publication Critical patent/GB2117311A/en
Application granted granted Critical
Publication of GB2117311B publication Critical patent/GB2117311B/en
Expired legal-status Critical Current

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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
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • 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
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0022—Combinations of extrusion moulding with other shaping operations combined with cutting
    • 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
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2021/00—Use of unspecified rubbers as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2030/00—Pneumatic or solid tyres or parts thereof
    • B29L2030/002—Treads

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

A method of and apparatus for extruding an uncured elastomer, e.g. rubber, to produce an elastomeric component, e.g. a tyre tread or sidewall, of predetermined cross- section. The elastomer is fed to an extrusion die 1 for producing an extrudate 2 having the required cross- section of the component and the extrudate 2 is retained in the required cross-section by retaining means 3 until it reaches a stable condition. The retaining means 3 comprises a former 4 and a follower which together define a channel 5 having a cross-section complementary to the extrudate 2. The retaining means 3 may include heating means 9. The former 4 may comprise a drum, or an endless belt following a sinuous path around rollers, and the follower comprises an endless belt. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a method of and apparatus for extruding elastomeric components This invention concerns improvements in or relating to a method of and apparatus for extruding elastomeric components.
It is known that uncured rubber shrinks lengthwise and expands in cross-sectional area after extrusion. This change in the dimensions of the extrudate from those setby the extrusion die is a problem where an extrudate of accurate predetermined dimensions is required, for example in tyre manufacture where individual components of the tyre such as the tread and sidewalls are formed by cutting an extrudate to the required length and subsequently assembled on a tyre building drum.
The normal practical solution to this problem is to allow the extrudate to reach a stable condition before it is cut to length by passing it over a succession of conveyors or rollers running at progressively reducing speeds during which time the afore-mentioned shrinkage and expansion of the extrudate to a final cross-section occurs. To produce a final cross-section of the required dimensions the dimensions of the extrusion die are adjusted by trial and error while a trial batch of the compound is extruded. However, this procedure is not entirely satisfactory because the die only gives a consistent result for subsequent batches of compound which are identical in processing characteristics with the trial batch and in practice nominally similar batches of compound can vary in their processing characteristics.
Accordingly unless the die is re-set for each batch of compound a variation in the final cross-section of the extrudate can occur which, if sufficiently great, results in any component cut therefrom being outside the required tolerances for satisfactory subsequent assembly. Adjustment of the die is a time consuming operation requiring skilled operators and is normally only made following assessment of routine quality control measurements.
It is an object of the present invention to provide a method of and apparatus for extruding uncured rubber to produce a component of predetermined cross-section which mitigates the afore-mentioned problems and disadvantages of the known processes.
According to one aspect the present invention provides a method of extruding an elastomeric coponent of predetermined cross-section comprising feeding elastomeric material to an extrusion due to produce a shaped output of the required cross-section, feeding the shaped output to retaining means engageable with the shaped output to maintain the output in said predetermined cross-section and holding the output in said predetermined cross-section by means of the retaining means until the output reaches a stable condition.
By the present invention the extrudate is held in the extruded cross-section for a time sufficient for the forces tending to cause shrinkage and expansion thereof to decay to zero so that on subsequent release of the extrudate it maintains the cross-section imparted thereto by the die. As a result the cross-section of the extrudate is determined solely by the dimensions of the die and is independent of variations in the processing characteristics of the compound extruded from one batch to the next. In consequence the extruder may be operated without adjustment of the dimensions of the die outlet once the latter has been set to the required cross-section.
Preferably the temperature of the extrudate is raised while the latter is held by the retaining means, it having been found that the rate of decay of deforming forces is accelerated thereby. The increase in temperature is carefully controlled to ensure the extrudate does not commence its curing cycle, this being particularly important for an extrudate of uncured rubber where the tack of the rubber while in its uncured condition is relied on to obtain satisfactory adhesion between subsequently assembled components.
According to a second aspect of the present invention apparatus for extruding an elastomeric compound of predetermined cross-section comprises an extrusion die having an output orifice of cross-section corresponding to the predetermined cross-section of the component and retaining means adjacent to the output orifice and engageable with the extrudate to maintain the extrudate in said predetermined cross-section until it reaches a stable condition.
Preferably the retaining means included heating means for increasing the temperature of the extrudate, it having been found that the rate of decay of the deforming forces is increased by an increase in temperature. Any increase in temperature is carefully controlled to ensure that the extrudate reaches the stable condition while in a substantially uncured condition suitable for subsequent processing.
Preferably the retaining means comprises a former positioned adjacent to the extruder outlet onto which the extrudate is fed and a follower for retaining the extrudate on the former.
Conveniently one or both of the confronting surfaces of the former and follower is/are profiled to define a channel or constant cross-section corresponding to the cross-section of the extrudate. Preferably the channel is formed by a groove in the surface of the former and the follower has a planar surface which closes the mouth of the groove.
The former may comprise a roller having a circumferentially extending annular groove of the required constant cross-section formed in the periphery thereof. Alternatively the former may comprise an endless belt having a longitudinally extending groove of the required constant crosssection formed in the outer surface thereof.
Preferably the belt is reinforced, for example by longitudinally extending substantially inextensible cords.
The follower conveniently comprises an endless belt mounted on guide rollers that are mutually adjustable to vary the length of the channel and the tension in the belt so that for a given extrudate the latter reaches a stable condition before leaving the channel.
Conveniently drive means for the retaining means is synchronised with the rate of extrusion to give a take-off speed equal to the speed through the extruder.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings wherein: Figure 1 is a side view of a first embodiment in accordance with the present invention; Figure 2 is a side view of alternative retaining means, and Figure 3 is a transverse cross-section of part of the retaining means shown in Figure 2.
The apparatus shown in Figure 1 of the accompanying drawings comprises an extrusion die 1 for producing an extrudate 2 of predetermined cross-section and retaining means 3 engageable with the extrudate for holding the extrudate in said predetermined cross-section until is reaches a stable condition whereupon it may be released without any tendency to shrink in length and increase in cross-sectional area. The extrudate 2 may consequently be cut to produce components, e.g. a tyre tread or sidewall, for subsequent assembly.
The retaining means 3 comprises a roller 4 having a continuous annular groove 5 of crosssection corresponding to the cross-section of the extrudate 2 and an endless belt 6 mounted on four rollers 7a, b, c and d positioned to guide belt 6 around a portion of the peripheral surface of the roller 4 to define with the groove 5 a closed channel 8 of fixed length and constant crosssection. Three of the rollers 7a, b and dare mounted on fixed areas of rotation and the fourth roller 7c is mounted on an adjustable axis of rotation to allow the tension in the belt 6 to be varied as desired. In a modification one of the rollers 7a, b is also mounted on an adjustalbe axis of rotation to allow the length of the channel 8 to be varied and/or to accommodate rollers having different diameters.
Roller 4 incorporates heating means 9 whereby the temperature of the roller 4 may be increased relative to the temperature of the extrudate leaving the die 1 to accelerate the rate of decay of the deforming forces while maintaining the temperature below that at which substantial curing of the extrudate would occur.
Referring now to Figures 2 and 3 there is shown an alternative construction of retaining means 10 comprising a pair of endless belts 11 and 12 mounted on separate guide rollers 1 3 and 14 respectively and arranged to pass around a set of common rollers 1 5 in overlying relationship.
One of the belts 11 is provided with a reinforcement defined by longitudinally extending inextensible cords 1 6 and is formed with a longitudinally extending groove 1 7 in its outer surface of constant cross-section corresponding to the cross-section imparted to an extrudate 18 by a die (not shown). The confronting surface of the other belt 12 defines with the groove 1 7 a channel 1 9 which follows a sinuous path of fixed length and constant cross-section around the rollers 1 5.
One of the rollers 14, indicated 1 4', is mounted on an adjustable axis of rotation to allow the tension in belt 12 to be adjusted and one or more of the rollers 1 5 incorporate heating means 20 for increasing the temperature of the extrudate passing along channel 19.
In use of the above-described apparatus the extrudate 2, 1 8 of predetermined cross-section leaving the die is fed into the channel 8, 1 9 of corresponding cross-section and held in the predetermined cross-section as it is advanced along the channel 8, 19 by the drive imparted to a roller 4 or belt 11 via a motor (not shown) the output of which is synchronised to the extrusion rate to give a take-off speed equal to the speed through the extruder, the length of the channel 8, 1 9 and the extrusion rate being selected so that on leaving the channel 8, 1 9 the extrudate is in a stable conditon.
To accelerate the rate of decay of deforming forces and therefore reduce the time taken for the extrudate to reach a stable condition the latter is heated as it passes along the channel 8, 1 9 by means of the heating means 9, 20, the increase in temperature being carefully controlled to ensure the extrudate is still substantially uncured on leaving the channel 8, 19.

Claims (18)

1. A method of extruding an elastomeric component or predetermined cross-section comprises feeding elastomeric material to an extrusion die to produce a shaped output of the required cross-section, feeding the shaped output to retaining means engageable with the shaped output to maintain the output in said predetermined cross-section and holding the output in said predetermined cross-section by means of the retaining means until the output reaches a stable condition.
2. A method according to claim 1 wherein the temperature of the extrudate is increased while the latter is held by the retaining means.
3. Apparatus for extruding an elastomeric component of predetermined cross-section comprises an extrusion die having an output orifice of cross-section corresponding to the predetermined cross-section of the component and retaining means adjacent to the output orifice and engageable with the extrudate to maintain the extrudate in said predetermined cross-section until it reaches a stable condition.
4. Apparatus according to claim 3 wherein the retaining means includes heating means.
5. Apparatus according to claim 3 or claim 4 wherein the retaining means comprises a former positioned adjacent to the extruder outlet onto which the extrudate is fed and a follower for retaining the extrudate on the former.
6. Apparatus according to claim 5 wherein one of both confronting surfaces of the former and follower is/are profiled to define a channel corresponding to the cross-section of the extrudate.
7. Apparatus according to claim 6 wherein the channel is formed by a groove in the former, the mouth of the groove being closed by the follower.
8. Apparatus according to any one of claims 5, 6 or 7 wherein the former comprises a roller.
9. Apparatus according to any one of claims 5, 6 or 7 wherein the former comprises an endless belt.
10. Apparatus according to any one of claims 5 to 9 wherein the follower comprises an endless belt.
11. Apparatus according to claim 10 wherein the follower belt is mounted on mutually adjustable guide rollers to vary the length of the channel and the tension of the belt.
12. Apparatus according to any one of claims 3 to 11 wherein drive means is provided for the retaining means.
1 3. Apparatus according to claim 1 2 wherein the drive means is synchronised with the rate of extrusion to give a take-off speed equal to the speed through the extruder.
14. A method of extruding an elastomeric component or predetermined cross-section substantially as hereinbefore described.
15. A method of extruding an elastomeric component or predetermined cross-section substantially as hereinbefore described with reference to the accompanying drawing.
16. A component made by the method according to any one of claims 1 , 2, 14 and 1 5.
1 7. Apparatus for extruding an elastomeric component or predetermined cross-section substantially as hereinbefore described.
18. Apparatus for extruding an elastomeric component or predetermined cross-section substantially as hereinbefore described with reference to the accompanying drawing.
1 9. A component made by the apparatus according to any one of claims 3 to 13, 17 and 18.
GB08304328A 1982-02-16 1983-02-16 Improvements in or relating to a method of and apparatus for extruding elastomeric components Expired GB2117311B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08304328A GB2117311B (en) 1982-02-16 1983-02-16 Improvements in or relating to a method of and apparatus for extruding elastomeric components

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8204493 1982-02-16
GB08304328A GB2117311B (en) 1982-02-16 1983-02-16 Improvements in or relating to a method of and apparatus for extruding elastomeric components

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GB8304328D0 GB8304328D0 (en) 1983-03-23
GB2117311A true GB2117311A (en) 1983-10-12
GB2117311B GB2117311B (en) 1985-10-23

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GB08304328A Expired GB2117311B (en) 1982-02-16 1983-02-16 Improvements in or relating to a method of and apparatus for extruding elastomeric components

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2138351A (en) * 1983-03-23 1984-10-24 Bates W & A Ltd Manufacture of elastomeric material components
EP0730939A2 (en) * 1995-03-09 1996-09-11 Bridgestone Corporation Method and apparatus for reducing shrinkage of extruded rubber member
GB2323057A (en) * 1996-02-17 1998-09-16 Adolf Seide Finishing machine for foil and plate manufacture

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB664787A (en) * 1948-05-12 1952-01-09 British Celanese Process and apparatus for producing polished thermoplastic sheets
GB732091A (en) * 1953-08-27 1955-06-15 Richard Alfred Fisch Curved extrusion process and apparatus
GB897383A (en) * 1957-06-15 1962-05-23 Kerpenwerk G M B H & Co Take-off apparatus for extruded materials
GB1087156A (en) * 1964-02-17 1967-10-11 Mobil Oil Corp Thermoplastic articles, apparatus and process for their manufacture
GB1086744A (en) * 1963-11-22 1967-10-11 Petzetakis Aristovoulos George Method of and apparatus for the calibration of tubes
GB1206111A (en) * 1966-10-15 1970-09-23 Dunlop Co Ltd Improvements in or relating to methods of extrusion
GB1408062A (en) * 1972-02-10 1975-10-01 Graenges Essem Ab Extruded materials
GB1446716A (en) * 1972-10-30 1976-08-18 Heggenstaller A Extrusion apparatus for the manufacture of cured moulded products
GB1453516A (en) * 1974-01-18 1976-10-27 Dainippon Toryo Kk Method for continuous extrusion moulding of thermosetting resins
GB1533007A (en) * 1975-08-12 1978-11-22 Heggenstaller A Apparatus for heat setting an extrudate of compacted fibrous or particulate material
GB1590231A (en) * 1978-03-03 1981-05-28 Air Scooters Ltd Method of manufacturing stakes

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB664787A (en) * 1948-05-12 1952-01-09 British Celanese Process and apparatus for producing polished thermoplastic sheets
GB732091A (en) * 1953-08-27 1955-06-15 Richard Alfred Fisch Curved extrusion process and apparatus
GB897383A (en) * 1957-06-15 1962-05-23 Kerpenwerk G M B H & Co Take-off apparatus for extruded materials
GB1086744A (en) * 1963-11-22 1967-10-11 Petzetakis Aristovoulos George Method of and apparatus for the calibration of tubes
GB1087156A (en) * 1964-02-17 1967-10-11 Mobil Oil Corp Thermoplastic articles, apparatus and process for their manufacture
GB1206111A (en) * 1966-10-15 1970-09-23 Dunlop Co Ltd Improvements in or relating to methods of extrusion
GB1408062A (en) * 1972-02-10 1975-10-01 Graenges Essem Ab Extruded materials
GB1446716A (en) * 1972-10-30 1976-08-18 Heggenstaller A Extrusion apparatus for the manufacture of cured moulded products
GB1453516A (en) * 1974-01-18 1976-10-27 Dainippon Toryo Kk Method for continuous extrusion moulding of thermosetting resins
GB1533007A (en) * 1975-08-12 1978-11-22 Heggenstaller A Apparatus for heat setting an extrudate of compacted fibrous or particulate material
GB1590231A (en) * 1978-03-03 1981-05-28 Air Scooters Ltd Method of manufacturing stakes

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2138351A (en) * 1983-03-23 1984-10-24 Bates W & A Ltd Manufacture of elastomeric material components
EP0730939A2 (en) * 1995-03-09 1996-09-11 Bridgestone Corporation Method and apparatus for reducing shrinkage of extruded rubber member
EP0730939A3 (en) * 1995-03-09 1997-05-21 Bridgestone Corp Method and apparatus for reducing shrinkage of extruded rubber member
US5846475A (en) * 1995-03-09 1998-12-08 Bridgestone Corporation Method for reducing shrinkage of extruded rubber
GB2323057A (en) * 1996-02-17 1998-09-16 Adolf Seide Finishing machine for foil and plate manufacture
GB2323057B (en) * 1996-02-17 2002-01-16 Adolf Seide Finishing machine for foil and plate manufacture

Also Published As

Publication number Publication date
GB8304328D0 (en) 1983-03-23
GB2117311B (en) 1985-10-23

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