CA2047812A1 - Manufacture of plastics articles - Google Patents
Manufacture of plastics articlesInfo
- Publication number
- CA2047812A1 CA2047812A1 CA002047812A CA2047812A CA2047812A1 CA 2047812 A1 CA2047812 A1 CA 2047812A1 CA 002047812 A CA002047812 A CA 002047812A CA 2047812 A CA2047812 A CA 2047812A CA 2047812 A1 CA2047812 A1 CA 2047812A1
- Authority
- CA
- Canada
- Prior art keywords
- moulded
- salt
- core
- plastics material
- bath
- 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.)
- Abandoned
Links
- 239000004033 plastic Substances 0.000 title claims abstract description 32
- 229920003023 plastic Polymers 0.000 title claims abstract description 32
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 12
- 239000000463 material Substances 0.000 claims abstract description 38
- 239000011162 core material Substances 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 29
- 239000002991 molded plastic Substances 0.000 claims abstract description 13
- 239000012266 salt solution Substances 0.000 claims abstract description 13
- 239000000155 melt Substances 0.000 claims abstract description 6
- 238000000465 moulding Methods 0.000 claims abstract description 5
- 150000003839 salts Chemical class 0.000 claims description 40
- 238000010438 heat treatment Methods 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 230000006698 induction Effects 0.000 claims description 7
- 239000002131 composite material Substances 0.000 claims description 6
- 239000000374 eutectic mixture Substances 0.000 claims description 6
- 230000000712 assembly Effects 0.000 claims description 5
- 238000000429 assembly Methods 0.000 claims description 5
- 230000008018 melting Effects 0.000 claims description 5
- 238000002844 melting Methods 0.000 claims description 5
- 239000007769 metal material Substances 0.000 claims description 4
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 3
- 238000007654 immersion Methods 0.000 claims description 3
- 229910052700 potassium Inorganic materials 0.000 claims description 3
- 239000011591 potassium Substances 0.000 claims description 3
- 235000010333 potassium nitrate Nutrition 0.000 claims description 3
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical class [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 3
- 235000010344 sodium nitrate Nutrition 0.000 claims description 3
- 239000000243 solution Substances 0.000 claims description 3
- 229920001169 thermoplastic Polymers 0.000 claims description 3
- 239000004416 thermosoftening plastic Substances 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 2
- 230000000717 retained effect Effects 0.000 claims description 2
- 229920001187 thermosetting polymer Polymers 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 239000003921 oil Substances 0.000 description 13
- 229910052787 antimony Inorganic materials 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910001092 metal group alloy Inorganic materials 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 239000013505 freshwater Substances 0.000 description 2
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- JWVAUCBYEDDGAD-UHFFFAOYSA-N bismuth tin Chemical compound [Sn].[Bi] JWVAUCBYEDDGAD-UHFFFAOYSA-N 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 235000013824 polyphenols Nutrition 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
- B29C33/52—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Cleaning By Liquid Or Steam (AREA)
Abstract
ABSTRACT
MANUFACTURE OF PLASTICS ARTICLES
A method for the manufacture of an article of moulded plastics material which may contain an embedded metallic component comprising forming a core of a material which melts at a temperature below that of the plastics material, moulding the plastics material around the core and then immersing the assembly of plastics material and core in a bath containing a heated salt solution for a time sufficient to remove the core material.
MANUFACTURE OF PLASTICS ARTICLES
A method for the manufacture of an article of moulded plastics material which may contain an embedded metallic component comprising forming a core of a material which melts at a temperature below that of the plastics material, moulding the plastics material around the core and then immersing the assembly of plastics material and core in a bath containing a heated salt solution for a time sufficient to remove the core material.
Description
l. 2~781~
MANUFACT~RE OF PLASTICS ARTICLES
This invention relates to the manufacture of articles of plastics material and in particular to the manufacture of articles by a "lost core" type of process in which plastics material is moulded with the aid of a fusible melt out mould core member which, subsequent to moulding, is removed by heating the mould core member to a molten state in which it can flow out from a cavity thereby deEined by the moulded plastics material. In particular, though not exclusively, the invention relates to the manufacture of composite type plastics articles comprising a combination of plastics and metallic materials.
In the manufacture of precision type engineering components it is conventional to use a low melting temperature metal alloy such as lead-tin-antimony or tin-bismuth for the mould core, these materials being suitable for pre-forming accurately to a required core shape.
Subsequent to moulding of plastics materal around the metal alloy core, the core is melted either by an electrical induc-tion heating technique or by thermal conduction such as from the heat of a hot oil bath.
The induction heating technique is not always suitable, especially if the moulded plastics material has been pre-moulded integrally with metal components.
Thus it may be required to provide the moulded plastics article with a large number of screw-threaded brass inserts to facilitate subsequent attachment of other components. The induction heating results in undesirable local heating of the inserts and the immediately adjacent plastics material. In some cases it is possible to shield the metallic components from the induction field, but this is not always possible and in the case of an article having e g a large number of distributed inserts it is not practical.
The hot oil bath technique therefore has generally been employed for composite type articles ' ~7~
MANUFACT~RE OF PLASTICS ARTICLES
This invention relates to the manufacture of articles of plastics material and in particular to the manufacture of articles by a "lost core" type of process in which plastics material is moulded with the aid of a fusible melt out mould core member which, subsequent to moulding, is removed by heating the mould core member to a molten state in which it can flow out from a cavity thereby deEined by the moulded plastics material. In particular, though not exclusively, the invention relates to the manufacture of composite type plastics articles comprising a combination of plastics and metallic materials.
In the manufacture of precision type engineering components it is conventional to use a low melting temperature metal alloy such as lead-tin-antimony or tin-bismuth for the mould core, these materials being suitable for pre-forming accurately to a required core shape.
Subsequent to moulding of plastics materal around the metal alloy core, the core is melted either by an electrical induc-tion heating technique or by thermal conduction such as from the heat of a hot oil bath.
The induction heating technique is not always suitable, especially if the moulded plastics material has been pre-moulded integrally with metal components.
Thus it may be required to provide the moulded plastics article with a large number of screw-threaded brass inserts to facilitate subsequent attachment of other components. The induction heating results in undesirable local heating of the inserts and the immediately adjacent plastics material. In some cases it is possible to shield the metallic components from the induction field, but this is not always possible and in the case of an article having e g a large number of distributed inserts it is not practical.
The hot oil bath technique therefore has generally been employed for composite type articles ' ~7~
2.
of plastics and metallic material. This avoids undeslrable local heating but other problems are encountered. Often the mould core is formed from lead tin antimony which melts at 187C; particularly in this case it is therefore necessary to use oil at approximately 200-210C but the conventional oils used for this purpose, e g water soluble polyethylene glycol type oils, have a flash point of 215~C and there is therefore a potential safety problem.
The use of a hot oil bath technique also leads to other potential problems. The oils degrade typically over a period of 3 months during which time the oil viscosity becomes progressively greater and thereby reduces the ability for good thermal conduction; thus the heating time required to melt a core becomes increased. Also the oil darkens with use and where the inserts are of an anodised type it is found that they become adversely marked by the oil.
The present invention seeks to provide an improved method for the manufacture of plastics articles by the lost core technique and a method particularly but not necessarily suitable for the manufacture of composite plastics articles comprising in combination metallic and plastics materials.
In accordance with one of its aspects the present invention provides a method for the manufacture of articles of moulded plastics material comprising forming a core member of a material which melts at a temperature below that of the moulded plastics material, moulding the plastics material around the core member then immersing the assembly of plastics material and core member in a bath containing a heated salt solution and maintaining the article in the salt solution for sufficient time to remove the core material.
It is envisaged that the salt solution will be maintained at a temperature greater than the meltiny point of the core material.
However, the invention does not exclude the 2~7~1~
possibility of a multi-form heating technique in which induction heatin~ is used to augment salt bath heating.
In that case the salt ba-th need not be heated to above the melting point of the core material but the salt bath temperature should be selected such that additional heating by an induction field, in the case of a moulded article having integral metal components, does not result in potentially damaging heating of those metal components and thus of the surrounding moulded plastics material.
A suitable salt solution is a eutectic mixture of inorganic salts. An example of a suitable solution is a eutectic mixture of potassium and sodium nitrates.
The method of the invention further envisages that the article may be retained in the salt bath solution for a time greater than that necessary to remove the core material whereby the salt bath may be employed to effect any necessary post-cure heat treatment of the plastics material.
It is envisaged that the invention will be of particular use in the manufacture of plastics articles of thermoplastics materials but it may be employed also for articles formed from thermosetting materials such as phenolics.
The moulded plastics article may be comprised substantially only of plastics material or it may be of a composite nature comprising plastics material and metallic material. Typically it will be of a composite construction comprising a moulded plastics body having embedded therein one or more metallic components.
It is envisaged that the method may comprise use of a conveyor type installation to sequentially introduce moulded assemblies of plastics material and moulded core material into a salt bath and then sequentially remove the articles of plastics material from the bath. Subsequent to immersion in the salt 2i~7~1~
4.
bath the articles may be sequentially immersed in a fl:rst water tank for preliminary washing and then rinsed in a second water tank.
The invention further envisages that contaminated water from the rinse or pre-wash tank may be fed to a zone of the salt bath, e g by spraying thereon, whereby the water is evaporated due to the heat of the salt bath and thereby to result in the salt remaining in the salt bath. The need for special waste treatment of salt contaminated water in the pre-wash bath (and also the rinse bath) is thereby avoided.
It is envisaged that the rinse bath may be supplied with fresh water and an equal volume of water transferred to the pre-wash bath from which, in turn, a similar volume of the salt contaminated water is fed to the salt bath for heating to vaporise the water and collect the salt. The salt bath may be of a zoned construction in which a first zone is used for treating the assemblies of plastics material and moulded cores and a second zone is used for treatment of the salt contaminated water.
One embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing which shows schematically apparatus for use in performing the method of the present invention.
An overhead conveyor system 10 is used to slowly move a series of moulded assemblies 11 into a salt bath 12. Each moulded assembly comprises a thermoplastics body portion moulded around a metal alloy core of lead-tin-antimony. The conveyor system is operated to move 510wly and result in each moulded assembly being submerged in the salt bath for a period of typically 2 hours. Subsequently the conveyor system 10 lifts the respective moulded articles from the salt bath, the cores then having been melted out from the moulded articles. The articles are then sequentially ~ ~3 4 7 '~
5.
moved by the conveyor through the wash and rinse baths 13 and 14 respectively.
The salt bath in this embodiment of the invention contains a eutectic mixture of potassium and sodium nitrates at a temperature of 210C where the moulded assemblies comprise moulded cores of lead tin antimony which melts at 187C.
It will be seen from the accompanying drawing that the salt bath 12 has an auxiliary zone 15 separated from the main zone 16 by a vertical baffle 17. The purpose of the zone 15 is to provide an area of heated salt solution 12' into which salt contaminated water from the wash bath 13 may be sprayed. A collection hood 18 facilitates extraction of steam from above the salt bath zone 15. Pipes 19 and 20 respectively interconnect the wash and salt baths and the rinse and wash baths whereby when fresh water is added to the rinse bath an equal volume of water may pass to the wash bath and in turn an equal volume of the salt contaminated water pass as a spray into the zone 15 of the salt bath.
Means, not shown, is provided for continuously circulating the salt solution through the bath 12 and heating the salt solution. Means, also not shown, additionally is provided for collecting the mould core material which has been melted from the moulded articles and has sunk to the bottom of the bath 12.
The use of a salt bath for melting the mould cores avoids the aforedescribed problem of undesirable localised heating in the case of articles having metal inserts and also avoids the problems associated with the conventional use of an oil bath. Further advantages arising from the use of e g a eutectic mixture of inorganic salts are that they have a higher specific heat than oil, thereby either enabling the melt time to be reduced or a lower temperature bath to be used for the same period of immersion as compared with oil.
Also they are non-inflammable and do not degrade significantly.
of plastics and metallic material. This avoids undeslrable local heating but other problems are encountered. Often the mould core is formed from lead tin antimony which melts at 187C; particularly in this case it is therefore necessary to use oil at approximately 200-210C but the conventional oils used for this purpose, e g water soluble polyethylene glycol type oils, have a flash point of 215~C and there is therefore a potential safety problem.
The use of a hot oil bath technique also leads to other potential problems. The oils degrade typically over a period of 3 months during which time the oil viscosity becomes progressively greater and thereby reduces the ability for good thermal conduction; thus the heating time required to melt a core becomes increased. Also the oil darkens with use and where the inserts are of an anodised type it is found that they become adversely marked by the oil.
The present invention seeks to provide an improved method for the manufacture of plastics articles by the lost core technique and a method particularly but not necessarily suitable for the manufacture of composite plastics articles comprising in combination metallic and plastics materials.
In accordance with one of its aspects the present invention provides a method for the manufacture of articles of moulded plastics material comprising forming a core member of a material which melts at a temperature below that of the moulded plastics material, moulding the plastics material around the core member then immersing the assembly of plastics material and core member in a bath containing a heated salt solution and maintaining the article in the salt solution for sufficient time to remove the core material.
It is envisaged that the salt solution will be maintained at a temperature greater than the meltiny point of the core material.
However, the invention does not exclude the 2~7~1~
possibility of a multi-form heating technique in which induction heatin~ is used to augment salt bath heating.
In that case the salt ba-th need not be heated to above the melting point of the core material but the salt bath temperature should be selected such that additional heating by an induction field, in the case of a moulded article having integral metal components, does not result in potentially damaging heating of those metal components and thus of the surrounding moulded plastics material.
A suitable salt solution is a eutectic mixture of inorganic salts. An example of a suitable solution is a eutectic mixture of potassium and sodium nitrates.
The method of the invention further envisages that the article may be retained in the salt bath solution for a time greater than that necessary to remove the core material whereby the salt bath may be employed to effect any necessary post-cure heat treatment of the plastics material.
It is envisaged that the invention will be of particular use in the manufacture of plastics articles of thermoplastics materials but it may be employed also for articles formed from thermosetting materials such as phenolics.
The moulded plastics article may be comprised substantially only of plastics material or it may be of a composite nature comprising plastics material and metallic material. Typically it will be of a composite construction comprising a moulded plastics body having embedded therein one or more metallic components.
It is envisaged that the method may comprise use of a conveyor type installation to sequentially introduce moulded assemblies of plastics material and moulded core material into a salt bath and then sequentially remove the articles of plastics material from the bath. Subsequent to immersion in the salt 2i~7~1~
4.
bath the articles may be sequentially immersed in a fl:rst water tank for preliminary washing and then rinsed in a second water tank.
The invention further envisages that contaminated water from the rinse or pre-wash tank may be fed to a zone of the salt bath, e g by spraying thereon, whereby the water is evaporated due to the heat of the salt bath and thereby to result in the salt remaining in the salt bath. The need for special waste treatment of salt contaminated water in the pre-wash bath (and also the rinse bath) is thereby avoided.
It is envisaged that the rinse bath may be supplied with fresh water and an equal volume of water transferred to the pre-wash bath from which, in turn, a similar volume of the salt contaminated water is fed to the salt bath for heating to vaporise the water and collect the salt. The salt bath may be of a zoned construction in which a first zone is used for treating the assemblies of plastics material and moulded cores and a second zone is used for treatment of the salt contaminated water.
One embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing which shows schematically apparatus for use in performing the method of the present invention.
An overhead conveyor system 10 is used to slowly move a series of moulded assemblies 11 into a salt bath 12. Each moulded assembly comprises a thermoplastics body portion moulded around a metal alloy core of lead-tin-antimony. The conveyor system is operated to move 510wly and result in each moulded assembly being submerged in the salt bath for a period of typically 2 hours. Subsequently the conveyor system 10 lifts the respective moulded articles from the salt bath, the cores then having been melted out from the moulded articles. The articles are then sequentially ~ ~3 4 7 '~
5.
moved by the conveyor through the wash and rinse baths 13 and 14 respectively.
The salt bath in this embodiment of the invention contains a eutectic mixture of potassium and sodium nitrates at a temperature of 210C where the moulded assemblies comprise moulded cores of lead tin antimony which melts at 187C.
It will be seen from the accompanying drawing that the salt bath 12 has an auxiliary zone 15 separated from the main zone 16 by a vertical baffle 17. The purpose of the zone 15 is to provide an area of heated salt solution 12' into which salt contaminated water from the wash bath 13 may be sprayed. A collection hood 18 facilitates extraction of steam from above the salt bath zone 15. Pipes 19 and 20 respectively interconnect the wash and salt baths and the rinse and wash baths whereby when fresh water is added to the rinse bath an equal volume of water may pass to the wash bath and in turn an equal volume of the salt contaminated water pass as a spray into the zone 15 of the salt bath.
Means, not shown, is provided for continuously circulating the salt solution through the bath 12 and heating the salt solution. Means, also not shown, additionally is provided for collecting the mould core material which has been melted from the moulded articles and has sunk to the bottom of the bath 12.
The use of a salt bath for melting the mould cores avoids the aforedescribed problem of undesirable localised heating in the case of articles having metal inserts and also avoids the problems associated with the conventional use of an oil bath. Further advantages arising from the use of e g a eutectic mixture of inorganic salts are that they have a higher specific heat than oil, thereby either enabling the melt time to be reduced or a lower temperature bath to be used for the same period of immersion as compared with oil.
Also they are non-inflammable and do not degrade significantly.
Claims (15)
1. Method for the manufacture of articles of moulded plastics material comprising forming a core member of a material which melts at a temperature below that of the moulded plastics material, moulding the plastics material around the core member then immersing the assembly of plastics material and core member in a bath containing a heated salt solution and maintaining the article in the salt solution for a sufficient time to remove the core material.
2. Method according to claim 1 wherein the salt solution is maintained at a temperature greater than the melting point of the core material.
3. Method according to claim l wherein induction heating is used to augment salt bath heating.
4. Method according to claim 3 wherein the salt bath is heated to a temperature which does not exceed the melting point of the core material.
5. Method according to claim 1 wherein the salt solution is a eutectic mixture of inorganic salts.
6. Method according to claim 5 wherein the salt solution is a eutectic mixture of potassium and sodium nitrates.
7. Method according to claim l wherein the article is retained in the salt bath solution for a time greater than that necessary to remove the core material.
8. Method according to claim 1 wherein the moulded plastics article is of a composite nature comprising plastics material and metallic material.
9. Method according to claim 8 wherein the article comprises a moulded plastics body having embedded therein at least one metallic component.
10. Method according to claim 1 wherein the plastics material is a thermoplastics material.
11. Method according to claim 1 wherein the plastics material is a thermosetting material.
12. Method according to claim 1 wherein a conveyor type installation is used sequentially to introduce 7.
moulded assemblies of plastics material and moulded core material into said salt bath and then sequentially remove the articles from the bath.
moulded assemblies of plastics material and moulded core material into said salt bath and then sequentially remove the articles from the bath.
13. Method according to claim 1 wherein subsequent to immersion of the moulded assembly of plastics material and moulded core the article is immersed in a first water tank for preliminary washing and then rinsed in a second water tank.
14. Method according to claim 13 wherein salt contaminated water from the rinse or pre-wash tank is fed to a zone of the salt bath thereby to return the salt to the salt bath.
15. Method according to claim 14 wherein the contaminated water is sprayed into a zone of the salt bath.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9016389.0 | 1990-07-26 | ||
| GB9016389A GB2246736A (en) | 1990-07-26 | 1990-07-26 | Removing a meltable core from a moulded plastics article by immersion in a heated salt solution |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2047812A1 true CA2047812A1 (en) | 1992-01-27 |
Family
ID=10679675
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002047812A Abandoned CA2047812A1 (en) | 1990-07-26 | 1991-07-24 | Manufacture of plastics articles |
Country Status (7)
| Country | Link |
|---|---|
| CA (1) | CA2047812A1 (en) |
| DE (1) | DE4124315A1 (en) |
| ES (1) | ES2047413B1 (en) |
| FR (1) | FR2665103A1 (en) |
| GB (1) | GB2246736A (en) |
| IT (1) | IT1251123B (en) |
| MX (1) | MX9100398A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9216043D0 (en) * | 1992-07-28 | 1992-09-09 | Dunlop Automotive Composites U | Manufacture of composite type plastics articles |
| GB2269771B (en) * | 1992-07-30 | 1996-05-22 | Masaru Nemoto | Method of moulding articles |
| EP1514674B1 (en) * | 2003-09-05 | 2006-11-02 | Société de Technologie Michelin | Manufacturing method for a core for molding of tyre, as well as correspondingly manufactured tyre and apparatus for tyre manufacturing |
| FR3128659A1 (en) * | 2021-11-03 | 2023-05-05 | Safran | DEVICE AND METHOD FOR REMOVING A METAL ALLOY CORE IN A PART MADE OF COMPOSITE MATERIAL. |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB207790A (en) * | 1922-11-30 | 1924-05-15 | Leonhard Deutsch | A process of hardening the products of condensation from phenols and aldehydes |
| GB557714A (en) * | 1941-11-07 | 1943-12-01 | Carborundum Co | Method of making abrasive articles |
| GB1218548A (en) * | 1967-05-09 | 1971-01-06 | Tenaplas Ltd | Improvements in or relating to heating devices for thermoplastic pipes |
| NL7801157A (en) * | 1977-02-28 | 1978-08-30 | Pont A Mousson | METHOD AND APPARATUS FOR MANUFACTURING PRODUCTS FROM CROSS-TURNED THERMOPLASTIC MATERIAL |
| US4464324A (en) * | 1981-09-21 | 1984-08-07 | Ozen | Apparatus and method for injection moulding of plastic parts of irregular shape, hollow or undercut form |
| WO1984003857A1 (en) * | 1983-03-28 | 1984-10-11 | Park Chem Co | Pressure molding process using salt cores and a composition for making cores |
| DE3829475C1 (en) * | 1988-08-31 | 1989-11-09 | Aeg-Elotherm Gmbh, 5630 Remscheid, De |
-
1990
- 1990-07-26 GB GB9016389A patent/GB2246736A/en not_active Withdrawn
-
1991
- 1991-07-23 DE DE4124315A patent/DE4124315A1/en not_active Withdrawn
- 1991-07-23 ES ES09101717A patent/ES2047413B1/en not_active Expired - Lifetime
- 1991-07-24 CA CA002047812A patent/CA2047812A1/en not_active Abandoned
- 1991-07-25 FR FR9109416A patent/FR2665103A1/en active Pending
- 1991-07-26 IT ITMI912081A patent/IT1251123B/en active IP Right Grant
- 1991-07-26 MX MX9100398A patent/MX9100398A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| IT1251123B (en) | 1995-05-04 |
| FR2665103A1 (en) | 1992-01-31 |
| GB2246736A (en) | 1992-02-12 |
| MX9100398A (en) | 1992-02-28 |
| ES2047413A1 (en) | 1994-02-16 |
| ITMI912081A1 (en) | 1992-01-27 |
| ITMI912081A0 (en) | 1991-07-26 |
| DE4124315A1 (en) | 1992-01-30 |
| GB9016389D0 (en) | 1990-09-12 |
| ES2047413B1 (en) | 1994-09-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |