GB2229669A

GB2229669A - Moulding reinforced hollow objects

Info

Publication number: GB2229669A
Application number: GB9006799A
Authority: GB
Inventors: Ian Stanley White; Graham Bank
Original assignee: CELESTION INT Ltd
Current assignee: CELESTION INT Ltd
Priority date: 1989-03-30
Filing date: 1990-03-27
Publication date: 1990-10-03
Anticipated expiration: 2010-03-27
Also published as: GB2229669B; GB9006799D0; HK104293A; GB8907146D0

Abstract

A generally closed, hollow object (10), such as a loudspeaker cabinet, is made of plastics material which is rotationally moulded and has integral internal reinforcement, e.g. tubes (16) moulded therein. The tubes (16) preferably extend from wall to wall of the object and in three mutually perpendicular directions. The tubes (16) may project out beyond the housing walls. <IMAGE>

Description

MOULDED OBJECTS AND MOULDING METHODS SPECIFICATION This invention relates generally to the moulding of objects, especially large hollow objects, and is more particularly concerned with stiffening or reinforcing arrangements for such moulded objects, and with methods of manufacture thereof.

One preferred application of the present invention is to the moulding of plastics loudspeaker cabinets.

It is known to make loudspeaker cabinets from plastics materials by the use of injection moulding techniques. However, the tooling costs for injection mouldings are very high and it is one object of the present invention to provide a loudspeaker enclosure which can be made from plastics material at much lower cost.

It is a further object of the present invention to provide a moulded plastics loudspeaker enclosure which is sufficiently stiff to behave properly acoustically.

It is yet a further object of the present invention to provide a loudspeaker enclosure or cabinet which is strong enough to withstand the rigours of "road use" in mobile music applications.

In accordance with one aspect of the present invention there is provided a plastics article which comprises a closed or substantially closed, generally hollow object moulded integrally with internal stiffening or reinforcing means.

The stiffening means may comprise tubes of plastics material which extend within and across the object, preferably from wall to wall. Preferably, these stiffening tubes extend in three mutually perpendicular directions.

In accordance with another aspect of the invention there is provided a method of moulding a closed or substantially closed, generally hollow object which comprises rotationally moulding the object and simultaneously moulding integral internal stiffening or reinforcing means within the object.

In order that the invention may be more fully understood, one embodiment of loudspeaker enclosure in accordance with the invention will now be described by way of example and with reference to the accompanying drawing which is a schematic illustration of a moulded plastics loudspeaker enclosure incorporating a stiffening arrangement in accordance with the invention.

As shown in the drawing, the loudspeaker enclosure comprises a box-like-housing 10 of plastics material, for example polyethylene or polypropylene. The front wall 12 of the enclosure or housing 10 is provided with a circular hole 14 for the mounting of a loudspeaker unit (not shown). The housing is internally stiffened by a plurality of integrally moulded stiffening "tubes" 16 which, as shown, extend in three mutually perpendicular directions, respectively at right-angles to opposite pairs of walls of the housing. In the illustrated embodiment there are two vertical tubes, three horizontal transverse tubes and two horizontal tubes extending from front to back of the housing.

However, the number and configuration of the internal stiffening tubes may be modified as desired. As illustrated, each of these stiffening tubes 16 is hollow and terminates in a hole in the housing wall.

The tubes 16 may have a diameter of the order of 50 mm.

The complete article can be made by rotational moulding.

Where the tubes 16 pass each other within the volume of the enclosure they can be interconnected in order to provide additional bracing. This interconnection can be effected by natural fusing together of the plastics material during the moulding operation, or alternatively by bonding, e.g. by means of adhesive, if the tubes are hard.

Although in the illustrated embodiment the tubes 16 are shown as ending flush with the external surface of the housing, they could alternatively be of greater length so as to extend beyond the housing walls. In this way they could provide attachment points for "hardware", i.e. for pole-mountings, flying, stacking, etc. This can also form a styling feature.

Alternatively, the ends of the tubes and the holes could be hidden by plastics caps, fabric, or some alternative masking or screening material. The tubes themselves could be fitted with end caps.

In order to reduce the number of apertures in the housing walls, some of the tubes 16 can end short of the housing walls, yet still provide a stiffening function, i.e. be "blind" tubes.

Although the invention has been described above with particular reference to loudspeaker enclosures, it is to be understood that the invention is applicable to the moulding of all large, generally hollow objects, particularly those of a volume greater than about 1 cu.

ft., where internal stiffening is necessary or desirable.

Claims

CLAIMS:

1. A method of moulding a closed or substantially closed, generally hollow object which comprises rotationally moulding the object and simultaneously moulding integral stiffening or reinforcing means within the object.

2. A method as claimed in claim 1, which includes moulding the object with a plurality of internal hollow reinforcing tubes of plastics material extending within and across the object.

3. A method as claimed in claim 2, which comprises moulding the object with said tubes extending in three mutually perpendicular directions.

4. A plastics article which comprises a closed or substantially closed, generally hollow object moulded integrally with internal stiffening or reinforcing means.

5. An article as claimed in claim 4, in which the stiffening or reinforcing means comprises tubes of plastics material which extend within and across the object.

6. An article as claimed in claim 5, in which said tubes extend in three mutually perpendicular directions.

7. An article as claimed in claim 6, in which the object is cuboid and the tubes extend respectively at right-angles to opposite pairs of walls of the object.

8. An article as claimed in claim 5, 6 or 7, in which the tubes are hollow and each terminates in a hole in a wall of the object.

9. An article as claimed in claim 5, 6 or 7, in which at least some of the tubes project out beyond the peripheral surface of the object.

10. An article as claimed in claim 5, 6 or 7, in which some of the tubes terminate within the body of the object.

11. An article as claimed in any of claims 5 to 10, in which the tubes are interconnected by natural fusing or by being bonded together.

12. An article as claimed in any of claims 4 to 11, which is a loudspeaker cabinet or enclosure.

13. An article as claimed in claim 12, which is generally cuboid in shape with a hole in one wall thereof for the mounting of a loudspeaker unit.

14. An article substantially as hereinbefore described with reference to the accompany drawing.