CA1107018A - Method of manufacturing rubber articles and means for carrying out said method - Google Patents
Method of manufacturing rubber articles and means for carrying out said methodInfo
- Publication number
- CA1107018A CA1107018A CA285,815A CA285815A CA1107018A CA 1107018 A CA1107018 A CA 1107018A CA 285815 A CA285815 A CA 285815A CA 1107018 A CA1107018 A CA 1107018A
- Authority
- CA
- Canada
- Prior art keywords
- rubber
- mould
- rubber compound
- bead
- vulcanization
- 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
Landscapes
- Tyre Moulding (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
The method uses in whole or in part, accelerated but unvulcanized rubber. Forming is done by injection, preserving the properties of plasticity and adhesive power of the rubber, after unmolding and before any vulvanization. The blanks and intermediate products thus fabricated are capable of being integrated, by subsequent successive operations of any type, into more complex assemblies. This method is especially useful in the manufacture of an assembly of a tire bead and an unvulcanized rubber filler strip, wherein the filler strip is injected onto the bead to form the assembly.
The method uses in whole or in part, accelerated but unvulcanized rubber. Forming is done by injection, preserving the properties of plasticity and adhesive power of the rubber, after unmolding and before any vulvanization. The blanks and intermediate products thus fabricated are capable of being integrated, by subsequent successive operations of any type, into more complex assemblies. This method is especially useful in the manufacture of an assembly of a tire bead and an unvulcanized rubber filler strip, wherein the filler strip is injected onto the bead to form the assembly.
Description
7~8 The present invention relates to a method of manufacturing pneumatic tyres.
Industrial products exist which are entirely or partially based on rubber whose composition, structure and geometric shape are relatively complex.
Their manufacture assumes the use of materials which are different both in their nature and their composition. It is necessary, mostly, to form a blank from intermediate elements, to produce a well-defined final structure. This is followed lastly, by the final moulding operation which simultaneously realises two objectives, on the one hand, the almost final dimensional shaping of the product and, on the other hand, the vulcaniæation of the rubber mixes.
The forming of the blank assumes very considerable labour and fabricating means. The moulding operation constitutes practically the last step in the manufacture.
The formation of the blank is an operation of assembling intermediate products of which the layout, carried out according to a given procedure, leads to the establishment of the final structure. It is important, at this stage of manufacture, to have intermediate products possessing good adhesionl that is to say the ability of each element to adhere or to sticlc to the structure in the course of fabrication without resorting to glueing agents. It is also important to have sufficient plasticity to ensure ease of shaping by the action of stresses.
It must be noted that the plasticity of the elements is, to a very great extent, one of the most difficult problems to master in the production of intermediate products having dimensional characteristics which are both very accurate and very faithfully reproduced.
In the course of the moulding operation, the vul-, ..
7~8 canization of the rubber mixed is carried out under thesimultaneous action of time, temperature and pressure. This irreversible transformation modifies the physical and chemical properties of the initial mixes by conferring elasticity on them and causing the properties of adhesion and plasticity to practically disappear.
The moulding operation always associates a dimen-sional shaping and a vulcanization, even partial, and hence a heat stabilising of the product.
There are known to exist injection moulding units for the fabrication of simple parts, in the sense that they use only a single rubber mix, but can be complex in their shape.
The mix is introduced directly into the closed mould, through an injection nozzle, after plasticizing of the rubber mix.
The advantage is the reduction in the time of vulcanization of the part since the injection temperature of the rubber is very close to its vulcanizing temperature.
Lastly, the adhesive power and plasticity of accelerated but unvulcanized rubbers and their capacity to `~ 20 preserve these properties as long as no vulcanization has taken place, are known.
The present invention provides a method of manufac-turing a pneumatic tyre comprising the ste~s of placing an annular bead in a mould adapted to receive an accelerated, ~`~ unvulcanized rubber compound by an injection system, plasticizinq said rubber compound at a temperature sufficient to plasticize the rubber compound yet insufficient to cause premature, partial vulcanization of the compound, injecting said rubber compound at a given temperature under high pressure into said mould to form a bead filler piece contiguous with said annular bead, the mould being maintained at a temperature which is such that 743~
-vulcanization of the rubber compound does not occur, removing said annular bead and bead ~iller assembly from said mould while the rubber compound is still in an unvulcanized state, assembling said assembly into a tyre and vulcanizing said tyre.
It is thus possible to produce in a single operation of the injection type an assembly of a bead filler and a bead core for subsequent use in the manufacture of a pneumatic tyre.
Tyre manufacturing methods previously necessitated use of several techniques leading to the fabrication of one or more parts in order to apply the bead filler and bead core during the assembly of a pneumatic tyre. These techniques have the intermediate drawbacks of storage, identification and preparation of the individual parts.
Other advantages of the present invention are that the dimensional qualities of the individual intermediate parts are improved, the moulding operation being more accurate. Due to the fact of the pressure utilised, any possibility of including air is elimina~ed. The droppings and rejects can be recycled, which is not the case with vulcanized elements. Moreover, the level of productivity i5 high.
Other characteristics and advantages of the present invention will emerge from the description which follows with reference to the accompanying drawing relating to the manufacture Of pneumatic tyres, without this however constituting a limitation ~; on the scope of the invention.
In the drawings:
Figure 1 shGws in perspective the assembly of components necessary for the production of the intermediate product;
Figure 2 is a sectional view along the line II-II of Figure l; and Figure 3 shows a type of mould with a centering device -for the core and a regulating device.
The method according to the invention comprises plasticiziny by any suitable means, an accelerated unvulcanized rubber mixture, then of injecting this rubber at a certain temperature into a closed mould which is kept at a chosen temperature. The temperature of the mould is chosen so that vulcanization of the moulded part, even at its surface, is avoided to preserve its previously described properties and also to permit eas~ and rapid unmoulding, without the inter-vention of specific mould release agents which could alter theproperties o~ adhesion of the rubber in the subsequent use of the intermediate product. Moreover, the physical properties of the mix develop in such a way that the distortion of the part is minimal in the course of the unmoulding operation.
The manufacture of a pneumatic tire requires rubber mixes with well-defined physical and chemical properties, cables of natural or synthetic style fibers, and steel wires, etc.
Recourse is made to extrusion to produce sectional elements and to calanderin~ for the preparation of compounds in sheets such as textile or metal layers. Subsequent operations of cutting, preparation and conditioning result in the fabric-ation of elements taking part in the composition of the blank.
To manufacture the "intermediate" product defined by the `~ bead core or strip, the covering of the bead and the filler rubber, these various elements are united~ in a final stage after a preparatory operation~
Thus, a metallic annular bead core 1 is introduced into the cold-forming mould 2 and the filler rubber 3 is injected at very high pressure through a nozzle 4.
The mould shown in Figure 3 is a multiple mould and i~ 7~B
hence composed of several complementary blocks or units (2a, 2b, ~c, etc.). Certain of these units are traversed by a cir-culation of fluid thxough passages 5 forming part of a temper-ature regulating device avoiding any vulcanization.
The units define between them a system of branches 6 for the distribution of the filler rubber, connected to the injection nozzle 4.
The metallic core 1 is held in its place in the mould space formed between two blocks, by a centering or holding device constituted by a ring 7 to which it is fastened. The ring is itself ensleeved on an annular wall 8 formed in one of the two blocks. On unmoulding, the ring 7 forms an integral part of the intermediate product, (Figure 2).
Generally, the invention enables parts of a pneumatic tyre to be manufactured by cold forming through an injection unit of accelerated but unvulcanized rubber. The rubber compound may be only a single rubber mix or may include several types of rubber mixes.
One or several supports of metal or material of other types may be incorporated to the tyres prior to the vulcanization step. The parts are assembled together due to the fact notably of their adhesive power and the group of parts thus assembled is vulcanized to obtain the predetermined final article.
It is to be well understood that the present invention has only been described and shown by way of preferential example and that equivalent modifications could be introduced into its constituent elements without however departing from the scope of saidinvention which is defined in the claims which ollow.
;~ -5-~` ?'
Industrial products exist which are entirely or partially based on rubber whose composition, structure and geometric shape are relatively complex.
Their manufacture assumes the use of materials which are different both in their nature and their composition. It is necessary, mostly, to form a blank from intermediate elements, to produce a well-defined final structure. This is followed lastly, by the final moulding operation which simultaneously realises two objectives, on the one hand, the almost final dimensional shaping of the product and, on the other hand, the vulcaniæation of the rubber mixes.
The forming of the blank assumes very considerable labour and fabricating means. The moulding operation constitutes practically the last step in the manufacture.
The formation of the blank is an operation of assembling intermediate products of which the layout, carried out according to a given procedure, leads to the establishment of the final structure. It is important, at this stage of manufacture, to have intermediate products possessing good adhesionl that is to say the ability of each element to adhere or to sticlc to the structure in the course of fabrication without resorting to glueing agents. It is also important to have sufficient plasticity to ensure ease of shaping by the action of stresses.
It must be noted that the plasticity of the elements is, to a very great extent, one of the most difficult problems to master in the production of intermediate products having dimensional characteristics which are both very accurate and very faithfully reproduced.
In the course of the moulding operation, the vul-, ..
7~8 canization of the rubber mixed is carried out under thesimultaneous action of time, temperature and pressure. This irreversible transformation modifies the physical and chemical properties of the initial mixes by conferring elasticity on them and causing the properties of adhesion and plasticity to practically disappear.
The moulding operation always associates a dimen-sional shaping and a vulcanization, even partial, and hence a heat stabilising of the product.
There are known to exist injection moulding units for the fabrication of simple parts, in the sense that they use only a single rubber mix, but can be complex in their shape.
The mix is introduced directly into the closed mould, through an injection nozzle, after plasticizing of the rubber mix.
The advantage is the reduction in the time of vulcanization of the part since the injection temperature of the rubber is very close to its vulcanizing temperature.
Lastly, the adhesive power and plasticity of accelerated but unvulcanized rubbers and their capacity to `~ 20 preserve these properties as long as no vulcanization has taken place, are known.
The present invention provides a method of manufac-turing a pneumatic tyre comprising the ste~s of placing an annular bead in a mould adapted to receive an accelerated, ~`~ unvulcanized rubber compound by an injection system, plasticizinq said rubber compound at a temperature sufficient to plasticize the rubber compound yet insufficient to cause premature, partial vulcanization of the compound, injecting said rubber compound at a given temperature under high pressure into said mould to form a bead filler piece contiguous with said annular bead, the mould being maintained at a temperature which is such that 743~
-vulcanization of the rubber compound does not occur, removing said annular bead and bead ~iller assembly from said mould while the rubber compound is still in an unvulcanized state, assembling said assembly into a tyre and vulcanizing said tyre.
It is thus possible to produce in a single operation of the injection type an assembly of a bead filler and a bead core for subsequent use in the manufacture of a pneumatic tyre.
Tyre manufacturing methods previously necessitated use of several techniques leading to the fabrication of one or more parts in order to apply the bead filler and bead core during the assembly of a pneumatic tyre. These techniques have the intermediate drawbacks of storage, identification and preparation of the individual parts.
Other advantages of the present invention are that the dimensional qualities of the individual intermediate parts are improved, the moulding operation being more accurate. Due to the fact of the pressure utilised, any possibility of including air is elimina~ed. The droppings and rejects can be recycled, which is not the case with vulcanized elements. Moreover, the level of productivity i5 high.
Other characteristics and advantages of the present invention will emerge from the description which follows with reference to the accompanying drawing relating to the manufacture Of pneumatic tyres, without this however constituting a limitation ~; on the scope of the invention.
In the drawings:
Figure 1 shGws in perspective the assembly of components necessary for the production of the intermediate product;
Figure 2 is a sectional view along the line II-II of Figure l; and Figure 3 shows a type of mould with a centering device -for the core and a regulating device.
The method according to the invention comprises plasticiziny by any suitable means, an accelerated unvulcanized rubber mixture, then of injecting this rubber at a certain temperature into a closed mould which is kept at a chosen temperature. The temperature of the mould is chosen so that vulcanization of the moulded part, even at its surface, is avoided to preserve its previously described properties and also to permit eas~ and rapid unmoulding, without the inter-vention of specific mould release agents which could alter theproperties o~ adhesion of the rubber in the subsequent use of the intermediate product. Moreover, the physical properties of the mix develop in such a way that the distortion of the part is minimal in the course of the unmoulding operation.
The manufacture of a pneumatic tire requires rubber mixes with well-defined physical and chemical properties, cables of natural or synthetic style fibers, and steel wires, etc.
Recourse is made to extrusion to produce sectional elements and to calanderin~ for the preparation of compounds in sheets such as textile or metal layers. Subsequent operations of cutting, preparation and conditioning result in the fabric-ation of elements taking part in the composition of the blank.
To manufacture the "intermediate" product defined by the `~ bead core or strip, the covering of the bead and the filler rubber, these various elements are united~ in a final stage after a preparatory operation~
Thus, a metallic annular bead core 1 is introduced into the cold-forming mould 2 and the filler rubber 3 is injected at very high pressure through a nozzle 4.
The mould shown in Figure 3 is a multiple mould and i~ 7~B
hence composed of several complementary blocks or units (2a, 2b, ~c, etc.). Certain of these units are traversed by a cir-culation of fluid thxough passages 5 forming part of a temper-ature regulating device avoiding any vulcanization.
The units define between them a system of branches 6 for the distribution of the filler rubber, connected to the injection nozzle 4.
The metallic core 1 is held in its place in the mould space formed between two blocks, by a centering or holding device constituted by a ring 7 to which it is fastened. The ring is itself ensleeved on an annular wall 8 formed in one of the two blocks. On unmoulding, the ring 7 forms an integral part of the intermediate product, (Figure 2).
Generally, the invention enables parts of a pneumatic tyre to be manufactured by cold forming through an injection unit of accelerated but unvulcanized rubber. The rubber compound may be only a single rubber mix or may include several types of rubber mixes.
One or several supports of metal or material of other types may be incorporated to the tyres prior to the vulcanization step. The parts are assembled together due to the fact notably of their adhesive power and the group of parts thus assembled is vulcanized to obtain the predetermined final article.
It is to be well understood that the present invention has only been described and shown by way of preferential example and that equivalent modifications could be introduced into its constituent elements without however departing from the scope of saidinvention which is defined in the claims which ollow.
;~ -5-~` ?'
Claims (4)
1. A method of manufacturing a pneumatic tyre comprising the steps of placing an annular bead in a mould adapted to receive an accelerated unvulcanized rubber compound by an injection system, plasticizing said rubber compound at a temperature sufficient ot plasticize the rubber compound yet insufficient to cause premature, partial vulcanization of the compound, injecting said rubber compound at a given tempera-ture under high pressure into said mould to form a bead filler piece contiguous with said annular bead, the mould being maintained at a temperature which is such that vulcanization of the rubber compound does not occur, removing said annular bead and bead filler assembly from said mould while the rubber compound is still in an unvulcanized state, assembling said assembly into a tyre and vulcanizing said tyre.
2. An method according to claim 1, wherein a single rubber mix is used.
3. A method according to claim 1, wherein several types of rubber mixes are used.
4. A method according to claims 1, 2 or 3, wherein additional elements of metal or other materials are included in the pneumatic tyre prior to vulcanization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA285,815A CA1107018A (en) | 1977-08-30 | 1977-08-30 | Method of manufacturing rubber articles and means for carrying out said method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA285,815A CA1107018A (en) | 1977-08-30 | 1977-08-30 | Method of manufacturing rubber articles and means for carrying out said method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1107018A true CA1107018A (en) | 1981-08-18 |
Family
ID=4109433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA285,815A Expired CA1107018A (en) | 1977-08-30 | 1977-08-30 | Method of manufacturing rubber articles and means for carrying out said method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1107018A (en) |
-
1977
- 1977-08-30 CA CA285,815A patent/CA1107018A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |