Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B1/00—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen
  • B30B1/003—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen by an elastic bag or diaphragm expanded by fluid pressure
• • 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
  • B29C33/0011—Moulds or cores; Details thereof or accessories therefor thin-walled moulds
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/04—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles using movable moulds
• • 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
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/40—Shaping or impregnating by compression not applied
  • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
  • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
  • B29C70/48—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs and impregnating the reinforcements in the closed mould, e.g. resin transfer moulding [RTM], e.g. by vacuum

Definitions

• This invention relates to a method of manufacturing shell- formed objects of plastic material in a closed mould and to a press for carrying out the method.
• Such closed- moulds as a rule comprise female mould and male mould which brought together to one unit between themselves creates a ormation room for forming the object that is to be formed.
• the plastic material is supplied to the female mould by being poured into the same and is then subjected to compression moulding pressure in connection with the application of the male mould onto the female mould. It is also possible to press the plastic material into the closed mould under pressure or to suck the plastic material into the formation room of the mould.
• fig 1 shows a cross section through an opened press according to the invention for manufacturing shell-formed objects of plastic
• figs 2 and 3 showing cross section in cassette wagon and together illustrate the preparation of a cassette functioning as a mould
• fig 4 shows the insertion of a prepared mould cassette into the press
• fig 5 shows in cross section the press with the inserted mould cassette in closed position and without compression moulding pressure
• fig shows in cross section the press provided with mould cassettes pressurized
• fig 7 shows in cross section a press for carrying out an alternative performance of the method according to the invention
• figs 8 and 9 illustrate the manufacture of a lower part and upper part respectively, of the cassette of the press.
• the press 1 is very simple regarding its construction and comprises a stand 6 carrying a form stable cassette support 7 having a relatively big mass and with a smooth top side 8 which regarding its form corresponds to or is in accordance with the under-side 9 of the lower part of the cassette and which is designed as a seat for the mould cassette 2.
• a distance from the top side 8 of the cassette support there are channels 1-0 for a circulating heat medium, for instance warm water, electrical conductors or similar arranged for heating the cassette support 7 to intended temperature.
• a top piece 11 carrying a form stable cassette counterstay 12 which is limitedly movable and has a big mass and a smooth side 13 which regarding its form corresponds to or is in accordance with the outer side 14 of the upper part of the cassette and which impressing position comprises the under-side of the cassette counterstay.
• the cassette counterstay 12 is at a distance from its side 13 provided with channels 10 for a circulating heating medium, for instance warm water, electrical heating conductors or similar for heating the counterstay 12 to intended temperature.
• the cassette support 7 of the press as well as the cassette counterstay 12 of the press may consist of an inexpensive material suitable for casting, for instance concrete, and may be formed by casting, the intende ' d mould cassette being used as a mould for giving the surfaces 8 and 18 facing each other in the pressing position of the press the intended form.
• the cassette counterstay 12 of the press is limitedly movably connected to the top piece 11 by carrying means 15 fixedly arranged in the counterstay which means 15 is connected with pneumatic or hydraulic loosening means 16 which allows the mentioned limited movability for the counterstay 12 in relation to the top piece 11 of the press and which is arranged on cross bars 17 of longitudinal supporting bars 18 connected with the top piece 11 and together with the top piece 11 carrying a pressure plate 19.
• press means 20 each means preferably being positioned right in front of its supporting bar 17, which means are shown in the form of pressure tubes closed at their ends and with a connection not closely shown in the drawings to a pressure medium source for receiving necessary compression moulding pressure .by insertion of a pressure medium under pressure in the pressure tubes functioning as press means 20.
• a pressure medium for instance water can be used as a pressure medium as well as air.
• pressure tubes are used as press means 20 it is suitable to have the pressure tubes somewhat longer than the cassette counterstay 12 so that the ends of the pressure tubes are outside the cassette counterstay 12 and to close the ends of the pressure tubes by means of strong end pieces which are mutually connected by means of a not extensible wire 21 for taking up the axial compressive forces.
• preparation of the mould cassette 2 in a well ventilated spraying box separated from the working room as to the rest takes place as a first step.
• a cassette wagon 22 onto which the lower part 3 of the mould cassette is applied and which is then inserted into the spraying box where the waxed formation surfaces 23 of the lower part of the cassette are provided with a thin layer of gelcote, where ⁇ after the lower part 3 of the cassette may stand quite open in the spraying box for after hardening of the applied gelcote layer.
• this applied gelcote layer will form the outer surface of the object that is to be produced.
• the top piece 11 of the press is pivoted by means of hydraulic or pneumatic cylinders not closely shown to closed position which is shown in fig 5 and in which position the top piece 11 is locked to the stand 6 of the press.
• the loosening means 16 is disconnected in that way that the cassette counterstay 12 is allowed to move in relation to the top piece 11 in order to be placed against the mould cassette 2 applied into the press 1.
• the cassette counterstay 12 has the same temperature as the cassette support 7, for instance 30-60°C.
• This closed position of the press is shown in fig 5 without compres ⁇ sion moulding pressure applied.
• Necessary compression moulding pressure can vary in dependence on size and form of the object that is to be manu ⁇ factured but by means of the press means 20 shown in the form of pressure tubes very large press forces can be achieved which gurantee that the plastic is brought to flow out in the intended way and fill the formation room completely even having very big objects regarding the area.
• the time that the mould cassette 2 needs to be in the press 1 under pressure is accordingly determined by the mentioned temperature difference and by the thickness of the cassette walls, and when the temperature has been achieved at which the hardening starts and develops heat itself, that is in the exotermic point of the exotermic graph of the plastic, the mould cassette 2 takes out of the press after that the press means 20 having been brought to release the pressure and the loosening means 16 have been connected in order to lift up the cassette counterstay 12 of the press from the cassette.
• the top piece 11 is loosened from the stand 6 in order to be brought to open position, whereafter the warm mould cassette 2 is lifted up from the press and is lowered to a cassette wagon 22 on which after hardening can take place until the plastic is completely harded through thanks to the fact that necessary heat is stored so to say in the mould cassette.
• the next preparated cassette may be inserted into the press for pressing in the previously described way and by using mould cassettes in accordance with the present invention a very rational and quick manufacture of objects is achieved and also of very big objects regarding the area. Since the heat is lifted so to say out of the press with the mould cassette the press does not need to be cooled as is the case in known technique in order to remove the additional heat achieved during the hardening course.
• the after hardening takes place freely from the press itself and when the hardening is completed the upper part 4 of the cassette is lifted 70 and the formed object can be taken out of the cassette 2 for being given a high polish, thereafter cassette treatment is made by cleaning and rewaxing the surfaces whereafter the cassette is again ready to be used and to be provided with a layer gelcote in previously described way.
• fig 7 is illustrated an alternative performance of the method according to the present invention differing from the previously described method by the fact that the plastic material is sprayed under pressure by means of a spraying equipment 30 into the cassette mould 2 arranged in the press, which can be mentioned flowing pressing in contrast to the previously described method which can be characterized as wet pressing.
• a spraying equipment 30 into the cassette mould 2 arranged in the press
• wet pressing When spraying the plastic material into the mould cassette with pressure, full compression moulding pressure is applied to the press which in this connection with its parts 6 and 12 functions as a counterstay.
• wet pressing that is with the plastic introduced without spraying, the pressing is made as has been previously described with an increasing compression moulding pressure.
• figs 8 and 9 is illustrated how the present press in a simple way can be utilized for manufacturing the lower part 3 and the upper part 4 respectively, of the cassette.
• the surfaces 8 of the press support 6 after having been waxed are provided with a layer 31 of glass fibre and wet plastic in a quantity giving the lower part of the cassette intended thickness.
• a premanufactured lower part 32 of the cassette having a reduced thickness On this layer 31 there is then applied a premanufactured lower part 32 of the cassette having a reduced thickness and on this -lower part there is then arranged an upper part 4 of the cassette provided with a master object 33 determining the form of the formation room 5 of the mould cassette.
• the press 1 is closed and necessary compression moulding pressure is established for forming the lower part of the cassette, the premanufactured lower part 32 of the cassette with the reduced thickness being intimately united with a layer 31 of the glass fiber reinforcement and the wet plastic in connection with the hardening of the plastic.
• an upper part 4 of the cassette in the press is illustrated in fig 9.
• a lower part 3 of the cassette in the support 6 of the press and in intended position on this lower part of the cassette is the master object 33 placed.
• a premanufactured upper part 35 of the cassette is applied with reduced thickness and onto the surface 13 of the cassette counterstay 12 of the press there is put a surface 36 of glass fibre and wet plastic in a quantity giving the final upper part of the cassette 4 intended thickness.
• the press is closed and the compression moulding pressure is established for forming the upper part of the cassette which is made in the same way as for the lower part of the cassette.
• the present inven- tion is also usable without supplying heat by instead providing the plastic material with a cold hardener which speeds up the hardening of the plastic material at room temperature and in certain cases it is also possible to let the mould cassette remain in the press until the plastic material is completely depth-hardened.
• the outer surface of the manu- factured object shall be painted the gelcote layer is excluded and instead a so called ' surface mat is applied.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20369378

Family Applications (1)

Country Status (7)

Cited By (2)

Citations (3)

• 1987
  • 1987-08-25 SE SE8703292A patent/SE8703292L/ not_active Application Discontinuation
• 1988
  • 1988-08-24 JP JP50697888A patent/JPH03502666A/ja active Pending
  • 1988-08-24 AU AU23173/88A patent/AU2317388A/en not_active Abandoned
  • 1988-08-24 WO PCT/SE1988/000435 patent/WO1989001859A1/en not_active Application Discontinuation
  • 1988-08-24 EP EP19880907438 patent/EP0377612A1/en not_active Withdrawn
• 1990
  • 1990-02-22 DK DK047890A patent/DK47890A/da not_active Application Discontinuation
  • 1990-02-23 FI FI900929A patent/FI900929A0/fi not_active IP Right Cessation

Patent Citations (3)

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