GB2209135A

GB2209135A - Casting plaster products

Info

Publication number: GB2209135A
Application number: GB8720487A
Authority: GB
Inventors: David Reid
Original assignee: CLANCAST PRODUCTS Ltd
Current assignee: CLANCAST PRODUCTS Ltd
Priority date: 1987-08-29
Filing date: 1987-08-29
Publication date: 1989-05-04
Anticipated expiration: 2007-08-29
Also published as: GB2209135B; GB8720487D0

Abstract

An elongate mould member 19, which is made by casting silicone rubber, has a trapezoidal cross-sectional configuration of which the non-parallel sides define a right angle. Its longer parallel side is engaged by a trapezoidal base member 23 and side walls 29 mounted to the base member 23 and extending beyond the mould member 19 serve to retain plaster 32 cast through the mould mouth 31. The plaster 32 may form a cornice. In Fig. 2 the features of shape or pattern are formed in the shorter parallel side of mould member 19, but in an alternative embodiment they may be formed in its longer parallel side, Figs. 4, 5 (not shown). <IMAGE>

Description

ELONGATE MOULDED PRODUCTS This invention relates to a method of and an appliance for use in making elongate moulded products in plaster or like settable material.

One example of an elongate moulded product is a cornice extending at a wall/ceiling juncture. In order to locate and seat on the wall and ceiling surfaces respectively, a cornice moulding defines two longitudinal back faces disposed mutually at a right angle. Thus, these two back faces, in a cross-sectional view, represent the non-parallel sides of a trapezoidal configuration. The architectural or display feature(s) of the cornice are disposed at the longer parallel side of the general trapezoidal configuration. Accordingly, the manufacture of such moulded products involves the need for a moulding technique for dealing with the "convergent shape problem" which arises where a desired pattern is disposed at the bottom of a hollow mould and the sides converged towards the mould mouth.

Another example of an elongate moulded product is a panel moulding which simply has a plain back. Such mouldings can be slender and their manufacture involves the need for a moulding technique for achieving consistent straightness and cleanliness of mould and associated supports.

According to one aspect of the present invention, there is provided a method of making an elongate moulded product, including the steps of forming an elongate mould member in a rubber-like material and having a cross-sectional shape of generally trapezoidal configuration and incorporating at one of the parallel sides of said configuration features of shape or pattern for reproduction in the product, engaging the non-parallel sides of said configuration by rigid support or wall means, and pouring a liquid plaster or like settable material on to the mould member.

According to another aspect of the present invention, there is provided an appliance for use in making an elongate moulded product, comprising an elongate mould member of a rubber-like material and having a crosssectional shape of generally trapezoidal configuration and incorporating at one of the parallel sides of the said configuration features of shape or pattern for reproduction in the product.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a cross-sectional view of mould-making apparatus for use in the making of an appliance in accordance with one aspect of the present invention; Fig. 2 is a cross-sectional view of moulding apparatus incorporating an appliance in accordance with one aspect of the present invention; Fig. 3 is a cross-sectional view of a cornice produced using the apparatus of Fig. 2; Fig. 4 is a cross-sectional view showing the preparation of an appliance in accordance with a second aspect of the present invention; and Fig. 5 is a cross-sectional view showing the use of an appliance in accordance with the second aspect of the present invention in the manufacture of an elongate panel moulding.

In Fig. 1 of the drawings, a base 10 carries two rows of support webs 11. The rows of support webs 11 are mutually parallel, and in each row the webs are spaced out longitudinally. The length dimension of the arrangement corresponds generally with the length dimension of the moulded product to be manufactured.

The webs 11 are left-and-right-handed, and each web defines an upward facing recessed face 12 having a step or abutment 13 at the lower end. Each set of faces 12 is disposed in a common plain lying at 450 to the horizontal. Thus, the included angle between the two sets of faces 12 is 900.

Each set of faces 12 carries a rectangular side board 14 which extends longitudinally over all of the webs 11. Each side board 14 can slide upwards and downwards on its set of support faces 12, and each side board 14 can be locked in position by clamp means 15 represented diagrammatically in Fig. 1. The components referenced 10 to 15 inclusive constitute the basic moulding-making jig.

A model or master 16, typically of a close-grained timber suitable for mould making, has desired architectural details formed on its upper side as seen in Fig. 1. The length dimension of the model 16 is that of the product required. The side edges of the model 16 are bevelled inwardly towards the lower side, each with a bevelled angle of 450 Primary locating strips 17 are secured to the model 16 so that the model can be located on the jig with the primary locating strips 17 resting on the steps 13. Thus, the model 16 is supported horizontally throughout its length and can be re-located in the jig precisely provided that the primary locating strips 17 are not altered. It will be observed in Fig. 1 that the primary locating strips 17 are somewhat less thick than the side boards 14.

When the model 16 is appropriately located in the jig, the lower longitudinal edges of the side boards 14 are brought into abutment with the model 16 and the two joint lines are sealed and made smooth using plasticine or such like material as shown by reference numeral 18. Each side board 14 is locked in position by operation of its locking means 15.

At each end of the model 16, there is provided a fluid-tight dam (not shown).

An elongate mould member 19 of a rubber-like material is produced by pouring liquid silicone rubber compound on to the model 16. It will be noted that the general configuration in cross-section of the mould member 19 is trapezoidal.

Before the liquid silicone rubber compound has set, an elongate locating rib 20 is partly immersed in the liquid rubber, the rib 20 being temporarily suspended by support members 21 shown in broken line.

The locating rib 20 is removed when the rubber has set, leaving a longitudinally extending locating recess 22 in the mould member 19.

Without disturbing the set mould member 19, a rigid base member 23 is formed in close contact with the mould member 19 using glass fibre reinforced resins. The base member 23 also closely contacts the side boards 14 and embraces secondary locators 24 which are permanently incorporated in the side boards 14.

In forming the base member 23, the reinforced resins are urged into the locating recess 22.

When the base member 23 has completely set, it is removed from the jig and so also is the mould member 19.

It is to be noted that the base member 23 can be replaced precisely in contact with the side boards 14 by virtue of engagement with the secondary locators24.

Since the base member 23 and the mould member 19 have have been moulded without any shifting of the side boards 14, it will be understood that by virtue of the locating recess 22 the mould member 19 and the base member 23 can be re-assembled easily and with precision so that the non-parallel side faces of the trapezoidal configurations align.

In Fig. 2, parts corresponding with those in Fig.

1 are given the same reference numerals. The base member 23 is fitted with fastener studs 25 projecting normal to the non-parallel sides of the trapizoidal configuration.

Also, the base member 23 is provided with fastener studs 26 projecting normal to the longer parallel side. The studs 26 permit the base member 23 to be secured to a table 27 equipped with a vibrating means 28. The mould member 19 is engaged with the base member 23 using the locating recess 22. Thereafter, rigid longitudinally extending wall members 29 of aluminium plate are secured to the base member 23 by means of the fasteners 25. The wall member 29 extends upwardly over the nonparallel sides of the mould member 19 and define a hollow mould space 30 which is upwardly convergent towards a mould mouth 31 provided by suitably flanged edge portions of the plates 29. The bottom of the hollow mould space 30 is defined by the architectural or pattern features incorporated in the mould member 19.

In order to produce an elongate moulded product 32, glass fibre re-enforced plaster is poured through the mouth 31 and the vibrator 28 operated in order to effect searching distribution of the plaster over the mould surfaces. When the product 32 has set, it can be removed easily from the mould following the simple action of removing the plates 29. Due to the accuracy of alignment between the base member 23 and the mould member 19, the plates 29 seal accurately on the non-parallel surfaces so that a minimum of unwanted plaster penetration occurs and further products can be produced with a minimum of mould cleaning.

In the event of damage occuring to the mould member 19, the base member 23 can readily be re-located in the jig by engagement with the secondary locators 24. Assuming that the model 16 is already positioned and the side boards 14 locked there against, a fresh mould member 19 can now be poured by introducing liquid silicone rubber compound through an aperture (not shown) in the base member 23. Thus, an exact replica of the original mould member 19 can be obtained.

By the use of simple plates 29 to define the hollow mould space 30, the trapezoidal configuration of the mould member 19 is reproduced in the mould space. Thus, the product 32 is ideally suited for a cornice for fitting at the juncture of a wall and ceiling as is illustrated in Fig. 3.

In Fig. 4, a model 33 of a simple plain-backed panel moulding is secured to a flat table or base 34 by means of fasteners 35. The length dimension of the model 33 correponds with the elongate moulded product required.

Longitudinally extending timber battens 36 are secured to the table 34 by means of fasteners 37, and the inside faces of the battens 36 are cut to define the non-parallel sides of a trapezoidal configuration.

Two fluid-tight dams (not shown) are provided one at each end of the arrangement. Thereafter, a liquid silicone rubber material is poured on to the model 33 to form an elongate mould member 38 which can be removed, when set, by dismantling the battens 36.

In Fig. 5, the elongate mould member 38 is simply supported in a length of close tolerance metal angle 39 mounted on a support 40 by means of support V blocks 41. The required elongate moulded product 42 is obtained simply by filling the mould space in the mould member 38 with re-enforced plaster and allowing it to set. This arrangement using the mould member 38 of generally trapezoid cross-sectional configuration is particularly convenient since close-tolerance angle section is readily available. Further, any particles which might otherwise interfere with contact between the non-parallel faces of the mould member 38 tend to drop into the lower portion of the support angle 39.

Claims

1. A method of making an elongate moulded product, including the steps of forming an elongate mould member in a rubber-like material and having a cross-sectional shape of generally trapezoidal configuration and incorporating at one of the parallel sides of said configuration features of shape or pattern for reproduction in the product, engaging the non-parallel sides of said configuration by rigid support or wall means, and pouring a liquid plaster or like settable material on to the mould member.

2. An appliance for use in making an elongate moulded product, comprising an elongate mould member of a rubber-like material and having a cross-sectional shape of generally trapezoidal configuration and incorporating at one of the parallel sides of the said configuration features of shape or pattern for reproduction in the product.

3. An appliance as claimed in claim 2, wherein the said features of shape or pattern are incorporated at the shorter of said parallel sides.

4. An appliance as claimed in claim 3, including a base member of substantially rigid material, the base member engaging the mould member at the longer of said parallel sides and having faces which are co-planar with respective non-parallel sides of said trapezoidal configuration.

5. An appliance as claimed in claim 4, including wall means mounted to the non-parallel faces of the base member and extending beyond the said shorter side for retaining plaster poured thereon.

6. An appliance as claimed in claim 2, wherein the said features of shape or pattern are incorporated at the longer of said parallel sides.

7. An appliance as claimed in claim 6, including a support bar of V-shaped cross-section engaging the non-parallel sides of said trapezoidal configuration.

8. An appliance as claimed in any one of claims 2 to 7, wherein the angle between the non-parallel sides of said trapezoidal configuration is a right angle.

9. A method of making an elongate moulded product, substantially as hereinbefore described with reference to Figs. 1 to 3 or Figs. 4 and 5 of the accompanying drawings.

10. An appliance for use in making an elongate moulded product, substantially as hereinbefore described with reference to and as shown in Fig. 2 or Fig. 5 of the accompanying drawings.