GB2179290A - Locating metal inserts in rotational casting moulds - Google Patents
Locating metal inserts in rotational casting moulds Download PDFInfo
- Publication number
- GB2179290A GB2179290A GB08619614A GB8619614A GB2179290A GB 2179290 A GB2179290 A GB 2179290A GB 08619614 A GB08619614 A GB 08619614A GB 8619614 A GB8619614 A GB 8619614A GB 2179290 A GB2179290 A GB 2179290A
- Authority
- GB
- United Kingdom
- Prior art keywords
- stud
- mould tool
- heat transfer
- rotational
- metal
- 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.)
- Withdrawn
Links
- 239000002184 metal Substances 0.000 title claims abstract description 45
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 45
- 238000010106 rotational casting Methods 0.000 title abstract 2
- 229920003023 plastic Polymers 0.000 claims abstract description 20
- 239000004033 plastic Substances 0.000 claims abstract description 20
- 229910001369 Brass Inorganic materials 0.000 claims abstract description 9
- 239000010951 brass Substances 0.000 claims abstract description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052802 copper Inorganic materials 0.000 claims abstract description 6
- 239000010949 copper Substances 0.000 claims abstract description 6
- 238000001175 rotational moulding Methods 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- 241000905957 Channa melasoma Species 0.000 claims 1
- 238000009826 distribution Methods 0.000 abstract description 3
- 230000007547 defect Effects 0.000 abstract 1
- 239000011347 resin Substances 0.000 description 7
- 229920005989 resin Polymers 0.000 description 7
- 239000000463 material Substances 0.000 description 5
- 238000000465 moulding Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000003570 air Substances 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000000843 powder 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
- B29C33/12—Moulds or cores; Details thereof or accessories therefor with incorporated means for positioning inserts, e.g. labels
-
- 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
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/20—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. moulding inserts or for coating articles
-
- 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
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/34—Component parts, details or accessories; Auxiliary operations
- B29C41/46—Heating or cooling
-
- 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
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/04—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
-
- 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
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/68—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts by incorporating or moulding on preformed parts, e.g. inserts or layers, e.g. foam blocks
- B29C70/70—Completely encapsulating inserts
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
In the rotational casting of hollow plastics articles, a metal insert (12) to be incorporated in the article (13) is located internally of a rotational mould tool (10) by apparatus comprising heat conductive fixing members (14). Each heat conductive fixing member has a stud (15) manufactured from brass or other metal having good thermal conductivity and of length sufficient for extending through the wall (11) of the mould tool into co-operation with the metal insert. An enlarged heat transfer surface (16) manufactured from brass, copper or similar metal having good thermal conductivity is attached to that end of the stud which is external of the mould tool, to provide an improved heat transfer from the exterior of the mould to the insert (12), and avoid defects which would otherwise arise from uneven distribution of the plastics (13) around the insert due to inadequate heat transfer into the insert. The enlarged surface (16) may be of a star shape (16), or of "U" shape (21, Figure 4). <IMAGE>
Description
SPECIFICATION
Method and apparatus for rotational moulding
This invention relates to rotational moulding and is particularly concerned with a method and apparatus for rotationally moulding hollow articles having metal inserts.
It is known to produce hollow articles from powdered plastics material by a rotational moulding process in which powdered plastics resin is tumbled in a heated mould tool. The mould tool is manufactured in two or more parts which are charged with a predetermined amount of powdered plastics resin before they are clamped together. The closed mould tool is attached to a motor driven spindle arrangement by which it is simultaneously rotated around two axes in planes at right angles to each other after being placed in a heated oven.The double revolving motion results in formation within the mould tool of a hollow article having an external shape which corresponds with the shape defined by the internal wall surfaces of the mould tool as the powdered plastics resin contacts the heated interiorwall surfaces ofthe mould tool and fuses to form walls of uniform thickness.When all of the powder has fused into a homogeneous layer on the walls ofthe mould tool the tool is cooled while still being rotated. After cooling the mould is opened and the moulded article is removed.
It is a requirement in producing some hollow articles by the rotational moulding process to incorporate metal inserts in the article, for example, metal dividing walls which extend internally of the hollow article between its walls or metal rings which are embedded with the walls of the hollow article. Such metal inserts are introduced into the mould tool before it is closed and are located by studs which project internallyofthe mouldtoolfrom its walls.
A problem has been encountered in obtaining even distribution ofthefused plastics resin around such metal inserts. This results from inadequate heat transfer into the metal insertfromthewall ofthe mould tool and gives rise to voids and surface discontinuties in the plastics material surrounding the metal insert.
In an attempt to overcome this problem it has been
proposed eithertothin the section ofthe mould tool wall inthevicinity ofa metal insertorto provide the wall of the tool in this area with an insert made from a
metal having a higher rate of heat transfer than the
metal from which the mould tool is constructed. Both ofthese proposals have been found to give riseto distortion of the mould tool wall when it is heated which may be detrimental to the shape ofthefinished article.
US-A-2830325 discloses a heat conductive pin for
use in the manufacture of resilient squeeze bulbs of the type used in connection with syringes by a mould
ing process. The shoulder portion ofthe pin is provided by a material having a high coefficient of heat
conductivity relative to the material of the shank portion of the pin. In the moulding process this provides for a larger build up of material around the shoulder
portion of the pin to produce the thickened neck section ofthe bulb. There is no disclosure ofthis heat conductive pin being used to transfer heat into a metal insert which isto be provided in afinished moulded article and it does not providethesolution to the problem with which we are concerned.
It is an object of the present invention to provide a method and an apparatus for manufacturing by rotational moulding a hollow plastics article having a metal insert whereby even distribution of fused plastics resin around the metal insert is obtained.
Accordingly, one aspect ofthe present invention provides a method of manufacturing by rotational moulding a hollow plastics article having a metal insert, characterised by the step of locating the metal insert internally of a rotational mould tool by heat conductive fixing members each comprising a stud of length sufficient for extending from an end which is external ofthe mould tool through the tool wall to an end adapted for co-operation with the metal insert and having an enlarged heattransfersurface attached to that end of the stud which is external of the mould tool.
The present invention also comprises a hollow plastics article manufactured according to the aforesaid method.
Another aspect of the present invention provides apparatus for locating a metal insert internally of a rotational mould tool priorto a rotational moulding process and for transferring heat from atmosphere ambientofthetool into the metal insertduringthe rotational moulding process, the apparatus comprising a heat conductive fixing member having a stud of length greaterthan the thickness of a wall of a rotational mould tool with which it is to be used and an enlarged heat transfer surface attached to one end of the stud.
The stud is preferably threaded over that length which co-operates with the metal insert although it may be plain and may be manufactured from brass, copper, steel or any other metal having good thermal conductivity. The enlarged heat transfer surface may be manufactured from brass, copper, or any other metal having good thermal conductivity.
In one embodiment of the invention the heattransfor surface is cross-shaped in transverse crosssection whilst in another embodiment it is U-shaped so as to provide a forked end.
Conversant with any special requirements of snape or dimension necessary to facilitate insertion ofthe heat conductive fixing member into the wall ofthe mould tool,the heattransfer surface will be ofdimen- sions such as are required to provide a surface area giving maximum transfer of heat into the metal insert in the shortest possible time.
The invention will now be further described, by way of example only, and with reference to the accompanying drawings in which:
Figure 1 is a section through part of a rotational mould tool wall having a metal ring located internally thereof by apparatus in accordance with one embodi ment of the invention; Figure2 is a view on arrow 'A' in Figure 1; Figure3 is a section through part of a rotational mould tool wall having a metal baffle located internallythereof by apparatus in accordance with another embodimentofthe invention; and Figure 4 is a view on arrow'B' in Figure 3.
Referring to Figures 1 and 2 ofthe drawings, a rotational mouldtool 10 comprising two or more parts (not shown) is manufactured from steel plate.
That part of the tool wall 11 shown in Figure 1 hasa metal ring 12 located internally thereof, the ring 12 being shown as an insert embodied within a wall portion of a finished rotationally moulded hollow plastics article 13.
The metal ring 12 is located and held in spaced relationship with respect to the internal surface ofthe tool wall 11 prior to formation of the rotationally moulded article 13 by apparatus in accordance with the present invention. In the embodiment of Figures 1 and2theapparatuscomprisesa pluralityofheat conductive fixing members 14 each having a threaded brass stud 15 provided with an enlarged heattransfer surface 16 at one of its ends. The threaded stud 15 is of a length sufficient for extending from that end having the heat transfer surface 16 through athreadedholeinthetoolwall 11 into threaded engagement with the metal ring 12. As seen in Figure 2 the heat transfer surface 16 is crossshaped in transverse cross-section and is manufactured from brass, copper or any other metal having high thermal conductivity.The heat transfer surface 16 is attached to the stud 15 by brazing or any other suitable means.
Referring now to Figures 3 and 4 ofthe drawings, a metal baffle 17 is incorporated asan insert in a rotationally moulded article 18. The baffle 17 is located and held in spaced relationship with respect to the wall 11 of a rotational mouldtool 10 by apparatus comprising heat conductive fixing members 19 (only one being shown in Figure 3). The heat conductive fixing member 19 comprises a threaded brass stud 20 having an enlarged heat transfer surface 21 at one end thereof. In this embodiment the heat transfer surface is formed from sheet copper which is bent to form a shaped fork end as seen in Figure 4.
In a method of manufacturing of a hollow plastics article by rotational moulding the mould tool is provided by two or more parts. Any metal inserts which are required to be incorporated within the finished article are located on the internal surfaces ofthewalls of the tool parts by apparatus in accordance with the invention such as the heat conductive fixing members 14 and 19. The tool parts are then charged with predetermined amounts of powdered plastics resin before being clamped together to close the tool. After closing the tool it is attached to a motor driven spindle arrangement by which it is simultaneously rotated around two axes at rightanglesto each other whilst in a hot air oven.
We havefound that heat conductive fixing members in accordance with the present invention ensure that sufficient heat is transferred from the ambient air within the oven into the metal inserts becausethe enlarged heat transfer surfaces, being manufactured from metal having a high coefficient of heat conductivity, ensure that heat is rapidly transferred through the stud portion of the fixing member into the metal inserts to raise the temperature of their surfaces to substantially that of the the internal surfaces of the tool walls so that powdered plastics resin contacting the surfaces of the metal inserts during rotation ofthe mould tool is fused into a homogeneous layertothe exclusion of voids and surface discontinuities.
Claims (14)
1. A method of manufacturing by rotational moulding a hollow plastics article having a metal insert, characterised by the step of locating the metal insert internally of a rotational mould tool priortothe rotational moulding process by heat conductive fixing members each comprising a stud of length sufficientfor extending from an end which is external of the mould tool through the tool wall to an end adapted for co-operation with the metal insert and having an enlarged heat transfer surface attached to that end of the stud which is external of the mould tool.
2. A hollow plastics article manufactu red accord- ing to the method claimed in Claim 1.
3. Apparatus for locating a metal insert internally of a rotational mould tool prior to a rotational moulding process and for transferring heatfrom atmosphere ambient ofthe tool into the metal insert during the rotational moulding process,the apparatus comprising a heat conductive fixing member having a stud of length greaterthan the thickness of a wall of the rotational mould tool with which it is to be used and an enlarged heattransfer surface attached to one end of the stud.
4. Apparatus as claimed in Claim 3, wherein the stud is threaded over part of its length.
5. Apparatus as claimed in Claim 3 or Claim 4, wherein the enlarged heat transfer surface is crossshaped in transverse cross-section.
6. Apparatus as claimed in Claim 3 or Claim 4, wherein the enlarged heat transfer surface is Ushaped so as to provide a forked end.
7. Apparatus as claimed in any one of Claims 3 to 6,wherein the stud is manufactured from brass.
8. Apparatus as claimed in any one of Claims 3 to 7, wherein the enlarged heat transfer surface is manu facturedfrom brass.
9. Apparatus as claimed in any one of Claims 3 to 7, wherein the enlarged heat transfer surface is manu- facturedfrom copper.
10. A method of manufacturing by rotational moulding a hollow plastics article, substantially as herein before described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.
11. A method of manufacturing by rotational moulding a hollow plastics article, substantially as herein before described with reference to and as shown in Figures 3 and 4 of the accompanying drawings.
12. Apparatus substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 oftheaccompanying drawings.
13. Apparatus substantially as hereinbefore described with reference to and as shown in Figures 3 and 4 of the accompanying drawings.
14. Any new or improved features, combinations and arrangements described, shown and mentioned or any of them together or separately.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB858520795A GB8520795D0 (en) | 1985-08-20 | 1985-08-20 | Rotational moulding |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8619614D0 GB8619614D0 (en) | 1986-09-24 |
| GB2179290A true GB2179290A (en) | 1987-03-04 |
Family
ID=10584022
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858520795A Pending GB8520795D0 (en) | 1985-08-20 | 1985-08-20 | Rotational moulding |
| GB08619614A Withdrawn GB2179290A (en) | 1985-08-20 | 1986-08-12 | Locating metal inserts in rotational casting moulds |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858520795A Pending GB8520795D0 (en) | 1985-08-20 | 1985-08-20 | Rotational moulding |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8520795D0 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2193464A (en) * | 1986-07-22 | 1988-02-10 | Rom Plastics Limited | A mould for use in rotational moulding |
| FR2636265A1 (en) * | 1988-09-09 | 1990-03-16 | Lin Pac Mouldings | PROCESS FOR ROTARY MOLDING OF AN ARTICLE COMPRISING AN INSERT |
| US4976910A (en) * | 1987-11-30 | 1990-12-11 | Richard Gatley | Method of making a cooling device |
| US6713009B2 (en) * | 2001-09-05 | 2004-03-30 | Rotational Molding Technologies, Inc. | Method and apparatus for molding plastics with elongated metallic cores |
| WO2006103064A1 (en) * | 2005-04-01 | 2006-10-05 | Daimlerchrysler Ag | Method for the connection of at least one built-in element arranged within a plastic receptacle to a wall of the plastic receptacle |
| FR2883954A1 (en) * | 2005-03-30 | 2006-10-06 | Jean Francois Vincent | Fibre-reinforced plastic container for gas-liquid contents under autogenous pressure, e.g. butane, propane or beer, made by rotational moulding with incorporation of inserts and other accessories |
| CN100425873C (en) * | 2002-09-22 | 2008-10-15 | 利纳克有限公司 | A linear actuator with self-locking spindle |
| US7985362B2 (en) | 2005-08-23 | 2011-07-26 | Gallagher Group Limited | Method of forming a housing |
| WO2015028059A1 (en) * | 2013-08-29 | 2015-03-05 | Promens Hockenheim Gmbh | Method for producing a hollow body, and hollow body |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB207857A (en) * | 1922-09-04 | 1923-12-04 | Arthur Colley Austin Shorter | A new or improved mascot for motor cars, motor cycles, and other vehicles |
| GB716466A (en) * | 1952-08-18 | 1954-10-06 | Vulco Chemical Company Ltd | Process for the production of hollow inflatable articles of rubber or like material |
| GB973431A (en) * | 1960-03-15 | 1964-10-28 | Mettoy Co Ltd | Improvements relating to the manufacture of inflatable articles |
| GB1362647A (en) * | 1972-03-23 | 1974-08-07 | Liskey Aluminum | Pedestal caps |
| GB1573269A (en) * | 1978-05-15 | 1980-08-20 | Scaffolding Supplies Ltd | Methods of making fork bolts and fork bolts so made |
| GB1592482A (en) * | 1976-09-22 | 1981-07-08 | Kohlhage Fr W | Manually operable screw and method for its manufacture |
| US4489028A (en) * | 1982-11-22 | 1984-12-18 | Masters William E | Kayak improvements |
-
1985
- 1985-08-20 GB GB858520795A patent/GB8520795D0/en active Pending
-
1986
- 1986-08-12 GB GB08619614A patent/GB2179290A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB207857A (en) * | 1922-09-04 | 1923-12-04 | Arthur Colley Austin Shorter | A new or improved mascot for motor cars, motor cycles, and other vehicles |
| GB716466A (en) * | 1952-08-18 | 1954-10-06 | Vulco Chemical Company Ltd | Process for the production of hollow inflatable articles of rubber or like material |
| GB973431A (en) * | 1960-03-15 | 1964-10-28 | Mettoy Co Ltd | Improvements relating to the manufacture of inflatable articles |
| GB1362647A (en) * | 1972-03-23 | 1974-08-07 | Liskey Aluminum | Pedestal caps |
| GB1592482A (en) * | 1976-09-22 | 1981-07-08 | Kohlhage Fr W | Manually operable screw and method for its manufacture |
| GB1573269A (en) * | 1978-05-15 | 1980-08-20 | Scaffolding Supplies Ltd | Methods of making fork bolts and fork bolts so made |
| US4489028A (en) * | 1982-11-22 | 1984-12-18 | Masters William E | Kayak improvements |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2193464A (en) * | 1986-07-22 | 1988-02-10 | Rom Plastics Limited | A mould for use in rotational moulding |
| US4976910A (en) * | 1987-11-30 | 1990-12-11 | Richard Gatley | Method of making a cooling device |
| FR2636265A1 (en) * | 1988-09-09 | 1990-03-16 | Lin Pac Mouldings | PROCESS FOR ROTARY MOLDING OF AN ARTICLE COMPRISING AN INSERT |
| US6713009B2 (en) * | 2001-09-05 | 2004-03-30 | Rotational Molding Technologies, Inc. | Method and apparatus for molding plastics with elongated metallic cores |
| CN100425873C (en) * | 2002-09-22 | 2008-10-15 | 利纳克有限公司 | A linear actuator with self-locking spindle |
| FR2883954A1 (en) * | 2005-03-30 | 2006-10-06 | Jean Francois Vincent | Fibre-reinforced plastic container for gas-liquid contents under autogenous pressure, e.g. butane, propane or beer, made by rotational moulding with incorporation of inserts and other accessories |
| WO2006103064A1 (en) * | 2005-04-01 | 2006-10-05 | Daimlerchrysler Ag | Method for the connection of at least one built-in element arranged within a plastic receptacle to a wall of the plastic receptacle |
| US7985362B2 (en) | 2005-08-23 | 2011-07-26 | Gallagher Group Limited | Method of forming a housing |
| WO2015028059A1 (en) * | 2013-08-29 | 2015-03-05 | Promens Hockenheim Gmbh | Method for producing a hollow body, and hollow body |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8520795D0 (en) | 1985-09-25 |
| GB8619614D0 (en) | 1986-09-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |