GB2267456A

GB2267456A - Mounting natches in moulds

Info

Publication number: GB2267456A
Application number: GB9311322A
Authority: GB
Inventors: Bernard Bloor
Original assignee: S V Keeling & Co Ltd
Current assignee: S V Keeling & Co Ltd
Priority date: 1992-06-04
Filing date: 1993-06-02
Publication date: 1993-12-08
Anticipated expiration: 2013-06-02
Also published as: GB2267456B; GB9211866D0; GB9311322D0

Abstract

A master mould (10) has a rubber body which defines an enclosed moulding area (16) in which a pattern (18) of a ceramic item to be formed is provided. Four rigid engagement members (20) are embedded in the floor of the moulding area (16). The members (20) comprise a cylindrical socket (22) and four spaced legs (24) extending from the closed base thereof. The cylindrical socket (22) can receive the male end of a natch (26) during moulding of a working mould such that the natch (26) will be retained in the working mould. A corresponding mould (32, Fig 4), is provided with rigid members (38) for mounting the female end of natches (26). The working moulds, which may be of plaster, are then used to produce ceramic articles. The rigid members may be metal, e.g. brass. <IMAGE>

Description

Improved Moulds This invention concerns improvements in or relating to moulds and particularly but not exclusively master moulds usable in the manufacture of working moulds for producing ceramic ware, and also components usable in such master moulds.

Conventionally many ceramic articles such as jugs, vases and handles are cast in plaster of paris working moulds. These working moulds are usually made in two parts to permit release of the ware from the moulds.

During casting it is essential that the two parts of the working mould are accurately aligned together to provide an article of the precise required shape and to avoid the formation of mould lines where the two parts meet.

Alignment of plaster of paris mould parts when joined together is generally provided by natches. These are provided on respective parts of the mould providing either a male projection or a corresponding female socket. The natches are usually made of plastics material and provide a projection on one end and a corresponding socket at the other end such that a single natch can be used in either a male or female form, dependent on their orientation. The natches are usually located in the plaster of paris mould parts during casting thereof.

Plaster of paris working moulds are usually cast in master moulds. Master moulds bear the required shape of the article and are filled with liquid plaster of paris which sets to provide working moulds. The master moulds are often formed of a flexible material which may comprise rubber. The flexible nature of the master moulds greatly eases removal of the cast working moulds therefrom. Respective openings or projections are provided in the master mould to accept natches in a required orientation. The openings/projections are usually integrally formed with the master moulds. When the cast working moulds are removed from the master moulds the natches are retained in the working mould and pulled from the openings/projections provided in the master mould.

A number of problems are often encountered with this system. Firstly, due to the flexible nature of the master mould and especially the openings/projections formed therein, accurate positioning of the natches in the working moulds is not always achieved. Secondly, and partly due to the flexible nature of the master moulds, there can be a tendency for the natches to adhere to the openings/projections in the master mould, thereby causing damage to the working mould and/or loose fitting of the natches therein. Further, due to the forces applied to the openings/projections, and particularly the latter, during removal of the cast working mould from the master mould, these parts of the master mould often wear or break during an early part of the life of the mould whilst the rest of the mould still has a long remaining working life.Obviously once the openings/projections have failed on a master mould the whole mould is redundant.

According to the present invention there is provided a master mould usable in the manufacture of working moulds, the master mould comprising a body defining an enclosed area including the profile of an article to be made from the working moulds, and a rigid member located such that a natch can be removably located thereon whilst extending into the enclosed area whereby when a working mould is cast in the master mould the natch is bonded into the working mould and remains in the working mould subsequent to removal thereof from the master mould.

Preferably a pair of such master moulds are provided usable in the manufacture of a pair of cooperable working moulds to make a single article, with the rigid member of one of the master moulds engagable with a male part of a natch and the rigid member of the other master mould engagable with a female part of a natch.

The body of the or each master mould is preferably made of a flexible material and desirably a rubber based material.

The or each rigid member is preferably embedded in the body.

The rigid member upon which a male part of a natch can be located preferably comprises an engagement part defining a cylindrical socket of a size to slidingly accept the male part of a natch, the opening of the socket being substantially flush with the surface of the body within the enclosed area.

The rigid member upon which a female part of a natch can be located preferably comprises an engagement part defining a projection upstanding from the surface of the body within the enclosed area. The projection preferably has a lower part which is of a size to slidingly fit within the female part of a natch, and an upper part of reduced diameter such that the natch only engages with the lower part of the projection, thereby permitting ready release of a natch therefrom. The upper part of the projection may be frusto-conical to enable easy location of a natch thereon.

The or each rigid member preferably also comprises a location part extending from the engagement part to ensure firm location of the rigid member in the body.

The location part may comprise a plurality of spaced legs which may extend substantially parallel to the surface of the body in the enclosed area, and desirably extend laterally from a lower part of the rigid member adjacent to the lower end of said member but not therebeyond.

The rigid members are preferably made of metal and desirably brass.

The invention also provides a rigid member usable in a master mould according to any of the preceding eigh paragraphs.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of a master mould according to the invention usable for making a working mould with male natches thereon; Fig. 2 is a sectional side view of a similar mould to Fig. 1 with natches placed thereon; Fig. 3 is a sectional view of a working mould made from the mould shown in Fig. 2; Figs. 4 and 5 are similar views respectively to Figs. 2 and 3 for a working mould with female natches thereon; Fig. 6 shows a rigid member as used in the mould of Fig. 4, with a corresponding natch; Fig. 7 is a plan view of the rigid member of Fig.

6; and Figs. 8 and 9 are similar views respectively to Figs. 6 and 7 but of the rigid member used in the mould of Fig. 2.

Figs. 1 and 2 show similar master moulds 10. The moulds 10 have a rubber body 12. The body 12 has a generally square configuration and has upstanding side walls 14 which define an enclosed moulding area 16. A pattern 18 of the ceramic item to be formed from working moulds produced in the mould 10, in this case a vase, is provided on the floor of the body 12.

Four rigid engagement members 20, of the type shown in Figs. 8 and 9, are embedded in the floor of the moulding area 16. The members 20 comprise a cylindrical socket 22 and four spaced legs 24 extending from adjacent the closed base thereof. The legs 24 are provided by two diametrically opposite lengths of circular section rod. The members 20 are located in the body 12 such that the opening of the socket 22 is substantially flush with the floor of the moulding area 16. In this embodiment the members 20 are made of brass.

Each length of rod extends for substantially 900 around the circumference of the outside of the socket 22 with each end thereof extending radially away from the socket 22 to provide a leg.

In use, natches 26 are located on each of the members 20 as shown in Fig. 2, with the male projection 28 of the natch 26 located in the socket 22. The moulding area 16 is then filled with liquid plaster of paris. Once the plaster of paris has set, the working mould 30 thus formed, as shown in Fig. 3 is removed from the mould 10. The body 12 can be flexed to ease removal of the mould 30. The natches 26 are retained in the mould 30 and slide out of the socket 22 as the mould 30 is removed from the mould 10. The male projection 28 of the natches 26 now project from the mould 20.

Figs. 4 and 5 show respectively a master mould 32 and working mould 34 formed therein which correspond to the master mould 10 and working mould 30 except that the natches 26 are located in the working mould 34 such that the female socket part 36 of the natches 26 is engagable with the male projection 28 on the working moulds 30.

To provide this configuration, rigid members 38 are provided in the body of the master mould 32 in a similar manner to the mould 10 except that the rigid members 38 comprise male projections 40 which extend into the moulding area 16, upon which are locatable female parts 30 of natches 26. The projection 40 comprises a first lower portion 42 of a size to slidingly fit in the female part 36 and a frusto-conical upper portion 44.

The working moulds 30, 34 can be joined together to define a single mould in which an article can be cast by slip casting or any other casting process.

There is thus described a master mould and rigid members therefor which provide a number of advantages.

The rigid member ensures a precise and correct alignment of the respective working moulds. The rigid members prevent any tendency for the natches to adhere thereon.

The rigid members being made of brass can be precisely machined such that a required force will be required to remove a natch therefrom. On the rigid member provided with a male projection only the lower portion of the male projection engages with a natch, and thus the force required to remove a natch therefrom is reduced. This arrangement would not be possible with an integral projection as such a projection would not be sufficiently rigid to retain the natch thereon. The rigid members of the invention are likely to be extremely hardwearing and thus should not fail before the expiriy of the working life of the mould. The described rigid members are of relatively simple construction and can thus be robustly and inexpensively manufactured as can master moulds containing such members.

Various modifications may be made without deparing from the scope of the invention. For example the moulds may be made from other than rubber material, and resin moulds may be usable. The number and/or configuration of rigid members in the master mould may be varied. The shape the size of the rigid member can be altered as is required by different natches.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims:

1. A master mould usable in the manufacture of working moulds, the master mould comprising a body defining an enclosed area including the profile of an article to be made from the working moulds, and a rigid member located such that a natch can be removably located thereon whilst extending into the enclosed area whereby when a working mould is cast in the master mould the natch is bonded into the working mould and remains in the working mould subsequent to removal thereof from the master mould.

2. A mould according to claim 1, in which the body of the master mould is made of a flexible material.

3. A mould according to claim 2, in which the body of the master mould is made of a rubber based material.

4. A mould according to any of claims 1 to 3, in which the rigid member is embedded in the body.

5. A mould according to any of the preceding claims, in which the rigid member comprises an engagement part upon which the natch is locatable.

6. A mould according to claim 5, in which the rigid member also comprises a location part extending from the engagement part to ensure firm location of the rigid member in the body.

7. A mould according to claim 6, in which the location part comprises a plurality of spaced legs.

8. A mould according to claim 7, in which the spaced legs extend substantially parallel to the surface of the body in the enclosed area.

9. A mould according to claims 7 or 8, in which the spaced legs extend laterally from a lower part of the rigid member adjacent to the lower end of said member but not therebeyond.

10. A mould according to any of the preceding claims, in which the rigid member is made of metal.

11. A mould according to claim 10, in which the rigid member is made of brass.

12. Moulding apparatus comprising a pair of master moulds according to any of claims 1 to 11 usable in the manufacture of a pair of cooperable working moulds to make a single article, with the rigid member of one of the master moulds engagable with a male part of a natch and the rigid member of the other master mould engagable with a female part of a natch.

13. Apparatus according to claim 12, in which the rigid member upon which a male part of a natch can be located comprises an engagement part defining a cylindrical socket of a size to slidingly accept the male part of a natch, the opening of the socket being substantially flush with the surface of the body within the enclosed area.

14. Apparatus according to claims 12 or 13, in which the rigid member upon which a female part of a natch can be located comprises an engagement part defining a projection upstanding from the surface of the body within the enclosed area.

15. Apparatus according to claim 14, in which the projection has a lower part which is of a size to slidingly fit within the female part of a natch, and an upper part of reduced diameter such that the natch only engages with the lower part of the projection, thereby permitting ready release of a natch therefrom.

16. Apparatus according to claim 15, in which the upper part of the projection is frusto-conical to enable easy location of a natch thereon.

17. A rigid member usable in a master mould according to any of claims 1 to 16.

18. A master mould substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

19.. A master mould substantially as hereinbefore described with reference to Fig. 4 of the accompanying drawings.

20. Moulding apparatus substantially as hereinbefore described with reference to Figs. 2-4 of the accompanying drawings.

21. A rigid member substantially as hereinbefore described with reference to Figs. 4, 6 and 7 of the accompanying drawings.

22. A rigid member substantially as hereinbefore described with reference to Figs. 2, 8 and 9 of the accompanying drawings.

23. Any novel subject matter or combination including novel subject matter disclosed in the foregoing specification or claims and/or shown in the drawings, whether or not within the scope of or relating to the same invention as any of the preceding claims.