GB2380445A - Casting apparatus - Google Patents

Abstract

Prototype component casting apparatus may comprise a vacuum cabinet containing a robot mechanism for mixing and degassing the casting material and then pouring into a mould. To increase the maximum mould size without increasing the pouring time and possibly causing premature curing of the casting material, herein two or more robot mechanisms 12, 13 with respective separate casting material containers 23 are used. Operation of the mechanisms is synchronised and they are so located as to minimise space taken up in the cabinet. Each mechanism comprises housings 14, 15 and cup holders 16, 17. Holder 16 supports containers 22 and holder 17 supports container 23. Stirrer 32 extends into container 23. Each holder 16 is tilted to allow content in container 22 to be poured into respective container 23, the holder 17 of which is tilted to allow container 23 to pour into mould cavity 7 through funnel 8 and ducts 5, 6. The apparatus can be used for wax moulding in which case the containers 22 may be omitted or left empty.

Description

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CASTING APPARATUS This invention relates to casting or moulding apparatus, more particularly but not exclusively, vacuum casting apparatus for casting plastics material or wax prototype components.

Moulding equipment for making prototype components in plastics material may comprise a cabinet containing a"robot"mechanism for pouring a first plastics resin component or hardener from a first beaker into a second beaker containing a second component and stirring the mixed components while maintaining the components under a vacuum to"degas"them. When ready, the robot then pours the mixed component into a duct leading to a mould having a cavity in the shape of the item to be moulded.

The maximum size of the item to be moulded may be limited because, as the size of the beakers and the amounts of the plastics components are larger, it takes longer to pour the mixed components into the ducts leading to the mould. During this longer time, the mixed components may start to cure.

According to the invention, there is provided casting apparatus comprising a cabinet, a robot mechanism in the cabinet for supporting a container holding casting material, agitating the material and pouring it into a mould and vacuum means for degassing the casting material, characterised in that the apparatus comprise a robot mechanism within the cabinet operable for supporting two or more respective casting material containers and tilting the containers to pour the contents thereof into a mould.

Advantageously, the apparatus comprises two or more robot mechanisms and each mechanism is operable for supporting two containers, one above the other for receiving first

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and second respective plastics material casting components, the mechanism being operable for moving said one container to pour the first component to the other container for it to mix with the second component and for moving the other container to pour the mixed components into said duct and thence to the mould Reference will now be made by way of example to the drawings in which :- Figure 1 is a sectional side view (on line t in Figure 2) of a casting machine; Figure 2 is a partly cut away front view of the machine, and Figures 3 and 4 are two views of a mechanism used in the machine showing different operations thereof.

The machine comprises a cabinet 1 with upper and lower compartments 2 and 3 The lower compartment 3 holds a mould 4 to which two ducts 5 and 6 are connected for supplying moulding material to the mould cavity 7. The tops of the ducts are connected to respective funnels 8 which have inlet portions 9 at the level of the floor of compartment 2.

The two compartments 2 and 3 have doors 11 (not''shown in Figure 2). An air pump (not shown) is provided in or in association with the machine for creating a vacuum therein.

In the upper compartment 2, there are two mechanisms 12 and 13 positioned side-by-side as shown. Each mechanism comprises a first housing 14, a second housing 15 and two Ushaped cup holders 16 and 17. Cup holder 16 is pivotably mounted via stub shafts 18 between two upwardly extending side portions 19 of housing 14. Cup holder 17 is pivotably

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mounted via stub shafts 20 between housing 14 and housing 15. Fixed to the stub shaft 20 that connects the cup holder 17 to the housing 15, there is an inverted L shaped housing part 21 with a top section 40which extends up and then over the central area of cup holder 17. The part 21 moves with the cup holder 17 when the latter is pivoted with respect to housing 15.

Holder 16 is operable to support a first cup shaped container or beaker 22 at an elevated position relative to a second similar container 23 supported by holder 17. Via stub shafts 18 and 20, the holders 16 and 17 are coupled to motor drives 30 and 31 respectively, each drive being controlled by an automatic control system (not shown) which advances the casting process through an automatic cycle. A rotary stirrer 32 is coupled to a motor 33 (also controlled by the control system) mounted in the top section 40 of the housing part 21 so that the stirrer 32 extends down into the container 23. Initially measured amounts of appropriate liquid plastics material casting components, e. g. respective polymers and curing agents, are placed in respective ones of the containers 22 and 23 of the two mechanisms 12 and 13. Then the containers are positioned in the appropriate holders. Each container has two side lugs 34 which can be engaged under matching overlying portions 35 at the tops of the sides of the holders 16 and 17 so as to retain the containers in place when the cup holders are tilted. The materials are then subjected to a vacuum to degass them. After degassing, each cup holder 16 is tilted so that the component in each container 22 is poured into the corresponding one of the two containers 23. In each container 23, the components are mixed and stirred by the respective rotary stirrer 32. When ready, the holders 17 are tilted so as to pour the contents of container 23 into the funnels 8. The contents then pass via ducts 5 and 6 to the mould cavity 7.

The automatic control system controlling the motor drives so, 30 and 33 is operable or can be programmed to operate such that the robot mechanisms 12 and 13 work in synchronism,

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i. e. so that the contents of the two containers 22 are poured into the containers 23 simultaneously and the contents of containers 23 are mixed and then poured into the respective funnels 8 simultaneously.

Figure 3 shows one of the mechanisms 12 and 13 with its container 22 being tilted so as to pour the first plastics casting component into the container 23. Figure 4 shows how, after degassing and mixing, the contents of container 23 is tipped into funnel 8. Figure 3 also shows how the stirrer 32 moves with cup holder 17 and container 23.

The machine shown can also be used for wax moulding. For wax moulding the container 22 of each mechanism 12 and 13 can be omitted or left empty. Each container 23 however, is provided with the required amount of wax pellets. The wax is then heated, the machine being provided with heater means (not shown). The wax is thereby melted, degassed under vacuum and stirred and the containers are tipped to pour the molten wax via funnels 8 and duct 5 or 6 into the mould 4.

Because there are two mechanisms 12 and 13, each with a two component capacity, relatively large castings can be produced compared with the case where only one mechanism IS provided but meanwhile, because the mechanisms are placed side-by-side so that, when in place, the cup 22 is behind cup 23 as seen through the door 11, the machine is more compact In the width direction than would be the case if the two mechanisms were each positioned with the cup 22 to the side of cup 33.

The machine could comprise more than two robot mechanisms such as 12 and 13. For example, the machine could be adapted to comprise say three or four robot mechanisms each with a capability for receiving two containers, mixing the contents of the containers and pouring the mixed contents via funnels to respectively three or four ducts to the mould.

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In a further embodiment (not shown), as well as there being two or more robot mechanisms, each mechanism comprises more than two cup holders and is operable for holding and tilting respectively two or more cups containing appropriate casting material components. Thus, one cup could be tilted to pour its contents (a first component), into a second cup where it is mixed with a second component and the contents of the second cup are then poured into a third cup and mixed with a third component. Alternatively, the contents of the first and second cups could be poured direct into the third cup. In each case, the mixed and degassed casting material is poured from the third cup into the mould cavity via a respective funnel and duct.

In yet another embodiment (not shown) the casting apparatus could comprise a single mechanism but with first and second cup holders each having a capacity for receiving two or more cups.

Claims (5)

1. CLAIMS 1 Casting apparatus comprising a cabinet, a robot mechanism in the cabinet for supporting a container holding casting material, agitating the material and pouring it into a mould and vacuum means for degassing the casting material, characterised in that the apparatus comprise a robot mechanism within the cabinet (1) operable for supporting two or more respective casting material containers (22,23) and tilting the containers to pour the contents thereof into a mould.
2. 2. Apparatus according to Claim 1, wherein the apparatus comprises two or more robot mechanisms (12,13) within said cabinet (1) each operable for supporting one or more casting matenal containers (22,23) and tilting the containers to pour the contents thereof into a mould.
3. 3. Apparatus according to Claim 2, including control means operable for synchronising the operation of said two or more mechanisms.
4. 4 Apparatus according to Claim 2 or 3, wherein each robot mechanism comprises two container holders (16,17) and motor means (30,31) for tilting the containers to pour casting material from one to another container and thence, after mixing, pouring casting material from the other container into the mould.
5. 5. Apparatus according to Claim 4, wherein said mechanisms are located in the cabinet so that the two container holders of each mechanism lie one behind the other when seen from the front of the apparatus.