GB2141188A

GB2141188A - A skirt member for the vacuum chamber of a vacuum-type brick forming machine

Info

Publication number: GB2141188A
Application number: GB08315922A
Authority: GB
Inventors: Shigeo Iwasaki; Hiroshi Haguchi; Kaoru Kawasaki
Original assignee: Mitsuishi Fukai Tekkosho KK
Current assignee: Mitsuishi Fukai Tekkosho KK
Priority date: 1983-06-10
Filing date: 1983-06-10
Publication date: 1984-12-12
Also published as: GB2141188B; GB8315922D0

Abstract

A skirt member is described for sealing the vacuum chamber of a vacuum-type brick forming machine in which a brick-making material is filled into a mould, then pressed and moulded in vacuo, which skirt member is made of a soft material such as rubber and has inner and outer ring portions 1 and 2 interconnected by a wall portion 3. The radial cross-section of the wall portion 3 is of generally U-shaped form, and the maximum wall thickness of each ring portion 1 and 2 is greater than that of the wall portion 3. <IMAGE>

Description

SPECIFICATION A skirt member for the vacuum chamber of a vacuum-type brick forming machine The invention relates to a skirt member for the vacuum chamber of a vacuum-type brick forming machine, and to such a machine fitted with a skirt member of the invention.

The inventors of the present invention have invented a so-called vacuum-type brick forming machine capable of accommodating various types of moulds and defining a vacuum chamber with as small a capacity as possible, whereby brick-making material is filed in the mould, and then is pressed and moulded in a vacuum by upper and lower plungers. A patent application was filled for this machine at the Japanese Patent Office, under the No.67386/1980 (Publication No. 162607/1981).

A skirt member is used in such a vacuum-type brickforming machine in order to form an expandible vacuum chamber. In view of its function, the skirt member is required to have excellent durability to withstand its expansion strokes, to be mounted in such a way as to assure an effective seal, to be able to expand over a relatively long stroke and to define a minimum capacity for the vacuum chamber, when contracted.

Said inventors carried out research on the skirt member to satisfy said requirements, and the present invention has resulted, which aims at providing a skirt member with a shape having as small a capacity as possible for the vacuum chamber and having an enhanced durability.

Accordingly, this invention provides a skirt member for the vacuum chamber of a vacuum-type brick forming machine in which brick-making material is pressed and moulded under a vacuum in said chamber defined around a mould and plunger, which skirt member comprises concentric inner and outer ring portions and a flexible wall portion extending therebetween which wall portion has a generally U-shaped radial cross-section, said ring portions and wall portion being formed integrally and said ring portions being of greater maximum thickness than said wall portion.

The skirt member according to the invention should be formed of a soft material such as a rubber, and has a doughnut-like shape comprising two concentric inner and outer ring portions integrally connected by a wall portion of a generally U-shaped cross-section.

The ring portions preferably have a rectangular cross-section but may have other appropriate configurations, such as triangular and circular sections.

Further, the inner and outer ring portions may have different cross-sectional forms.

Irrespective of the configuration of the ring portions, the wall portion initially extends from the ring portions perpendicularly thereto, and then follows a moderate curve. The region of the connection between each ring portion and the wall portion preferably has a rounded profile, rather than a sharp corner. Each ring portion has greater maximum cross-sectional thickness than the wall portion, and though the wall portion preferably has a substantial ly uniform thickness throughout, it may be provided, where necessary, with radial or concentric ribs for reinforcement or the like.

The ring portions and the wall portions may be made of any flexible material having sealing properties, including natural and synthetic rubbers. The wall portion may of course be reinforced with cloth material, wires, and the like.

The invention extends to a vacuum-type brick forming machine whenever incorporating a skirt member of this invention as described above.

The invention will now be described in detail with reference to the attached drawings showing preferred embodiments of the invention, in which Figure lisa diametral cross-section of an embodiment of skirt member according to the invention; Figure 2 is a top plan view of said skirt member; Figure 3 is an enlarged cross-section taken along line Ill-Ill on Figure 2; Figures 4(a) - (c) are partial sectional views showing the skirt member mounted on a vacuumtype brick forming machine; and Figures 5(aJ and 5(b) show two alternative forms for the ring portions of the skirt member.

Referring to Figures 1 and 2, the skirt member comprises inner and outer ring portions 1 and 2, integrally connected by a wall portion 3 extending therebetween and having a generally U-shaped cross-section. As best shown in Figure 3, the ring portions 1 and 2 have a generally rectangular cross-section. The wall portion 3 extends from the ring portions 1 and 2 substantially perpendicularly to their peripheral walls, then makes a moderate downward curve which is reversed before reaching the lowermost point so that the radial section has a symmetrical configuration.

Since the ring portions 1 and 2 have rectangular cross-sections and are considerably thicker than the wall portion 3, the skirt member may be secured in position in a vacuum-type brick forming machine by the ring portions 1 and 2 in a sealing manner, so as to be restrained against accidental detachment.

Specifically, the cross-sectional thickness of the ring portions increases their engagement area to facilitate the sealing engagement thereof, whereas the use of a so-called dovetail or re-entrant joint may prevent the accidental detachment of the skirt member. Therefore the thickness of the ring portions may be varied according to the required configuration of their cross-section. Where the ring portions have, for example, a circular cross-section, (Figure 5(c)), the diameter preferably is relatively large as compared with the case of a rectangular cross-section. The skirt member of the invention is usually secured to a flange 4 and a plunger 7 of the brick forming machine by means, for example, of clamp members 9, so that the convex surface of the skirt member faces the vacuum chamber.By such an arrangement, the capacity of the vacuum chamber is kept as small as possible and, when the chamber is reduced to a vacuum, the skirt member may receive the atmospheric pressure load uniformly throughout.

The skirt member according to the invention operates in conjunction with a vacuum-type brick forming machine as follows.

Referring to Figure 4(a), showing the arrangement at the start of operation, first the flange 4 is lowered until, as shown in Figure 4(b), its lower end abuts the upper end of a mould to define a sealed vacuum chamber 6, a seal member 10 being used where necessary. The skirt member thus is at its fully stretched state. Then, the plunger7 is lowered to press and mould a brick-making material 8 under a vacuum, as shown in Figure 4(c). At this time the capacity of the vacuum chamber is reduced tU- a minimum. Upon completion of the moulding, the plunger 7 and flange 4 are raised to assume the respective positions shown in Figure 4(a).

The skirt member of the invention, with the shape and operation as described above, has a very long expansion stroke, but does not receive great alternate bending stresses, and varies in shape during the operation in a smooth manner. The skirt also receives the atmospheric pressure load uniformly all over. The skirt member of the invention thus enjoys an excellent durability over its repeated expansion strokes. Further, the capacity of the vacuum chamber is kept to the smallest possible during operation and is limited to a minimum at the time of pressing and moulding, which is most preferable for the pressing and moulding process.

Claims

1. A skirt member for the vacuum chamber of a vacuum-type brick-forming machine in which brick making material is pressed and moulded under a vacuum in said chamber defined around a mould and plunger, which skirt member comprises concentric inner and outer ring portions and a flexible wall portion extending therebetween which wall portion has a generally U-shaped radial cross-section, said ring portions and wall portion being formed integrally and said ring portions being of greater maximum thickness than said wall portion.

2. A skirt member according to claim 1, wherein the ring portions have a rectangular radial crosssection.

3. A skirt member according to claim 1, wherein the ring portions have a triangular radial crosssection.

4. A skirt member according to claim 1, wherein the ring portions have a circular radial cross-section.

5. A skirt member according to any of the preceding claims, wherein the ring portions and the wall portion are made of a natural or synthetic rubber material.

6. A skirt member according to any of the preceding claims, wherein the region of the connection between each ring portion and the wall portion has a rounded profile.

7. A skirt member according to claim 1 and substantially as hereinbefore described, with referpence to and as illustrated in the accompanying drawings.

8. Avacuum-type brick-forming machine whenever incorporating a skirt member according to any of the preceding claims.