GB2232920A

GB2232920A - Gas pressure ejection of a moulded article

Info

Publication number: GB2232920A
Application number: GB9004031A
Authority: GB
Inventors: David Peter Oliver
Original assignee: CARTER HOLT HARVEY ROOFING ALU
Current assignee: CARTER HOLT HARVEY ROOFING ALU
Priority date: 1989-02-23
Filing date: 1990-02-22
Publication date: 1991-01-02
Also published as: AU5010390A; GB9004031D0

Abstract

The moulded article (1) is ejected from a mould tool (3) by opening a valve (5) in the moulding surface of the mould tool e.g. actuated by means of a cam (10, 11) and passing gas from a gas feed passage (7) through the valve (5) towards the moulding surface, so that it passes between the surface and article to effect gas pressure ejection of the article from the surface. After the ejection the valve is reclosed, either by the reverse action of the valve opening means, or by resilient biasing means e.g. a spring (14). A plurality of valves may be provided in the moulding surface, supplied from a common gas manifold (21). <IMAGE>

Description

Improvements in or relating to Mould Ejection Apparatus and/or Methods This invention relates to apparatus and/or methods for achieving ejection of a moulded article from a mould tool.

It is an object of the invention to provide an apparatus and/or a method for achieving ejection of a moulded article from a mould tool, which will at least provide the public with a useful choice.

Accordingly, in one aspect, the invention may broadly be said to consist in an apparatus for achieving ejection of a moulded article from a mould tool comprising: a valve in communication with a moulding surface of said mould tool; gas feeding means in communication with said valve; said valve when open allowing passage of gas from said gas feeding means to said moulding surface, and when closed preventing such passage of gas; opening means to open said valve; and biasing means to reclose said valve.

In a further aspect the invention consists in a mould tool including one or more apparatus for achieving ejection of a moulded article from said mould tool according to any of the preceding paragraphs.

In a yet further aspect the invention consists in a method of ejecting a moulded article from a mould tool, comprising the steps of: opening one or more valves in a moulding surface of said mould tool; passing a gas or gases through said valve or valves towards said moulding surface so as to pass between said moulding surface and a moulded article thereon; reclosing said valve or valve once said article has been ejected from said tool.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

The presently preferred form of the invention will now be described with reference to the accompanying figures, wherein: Figure 1 shows a cross-sectional elevation of an apparatus for achieving ejection of a moulded article from a mould tool according to the invention; Figure 2 shows an end-on view of the cam rods and link rod and actuating means system for operating an array of apparatus in accordance with the invention; Figure 3 shows a view of one cam rod taken along AA in Figure 2; Figure 4 shows a similar view to Figure 1 but with the inclusion of a valve bucket; and Figure 5 shows one possible array of valves and air manifold for use in accordance with the invention.

Refering now to the Figures, an apparatus is provided for achieving ejection of a moulded article or part article 1 from a mould tool which comprises, in Figure 1, two parts, 3 and 4.

The mould tool may be in a variety of materials, including metal (such as steel, aluminium, or other suitable metallic compounds), plastics (such as polyester), wood and silicone rubber. These tools may be used for example in hot press moulding, ejection moulding, vacuum forming, resin injection, transfer moulding, cold moulding and hand layup.

The article 1 is moulded between the moulding surfaces of the mould tool 3 and 4. After moulding, part 4 of the mould tool is removed, and the moulded article 1 must then be ejected from the part 3. To achieve this in accordance with the invention, one or more valves 5 are provided in communication with the moulding surface 6 of the mould tool, on which the moulded article 1 remains after the removable tool face 4 is removed. Gas feeding means such as gas feed passage 7 are provided in communication with each valve 5.

Liquid supply means (not shown), such as a special purpose or proprietary in-line atomiser may be provided in association with the gas feeding means so as to introduce lubrication in the form of an external liquid mould release agent (for example, a silicone release agent) into the gas stream fed to the valve, in a controlled fashion.

The valve 5 when open allows passage of a gas or gases, such as air, together with the atomised release agent, if provided, from the gas feeding means 7 to the moulding surface 6, and when closed prevents such passage of gas. In Figure 1, the valve 5 is shown partially open allowing some passage of gas through the air feed passage 7. When open, the valve head surface 9 preferably projects from the plane of the moulding surface 6.

The valve 5 is opened by any suitable opening means, such as a cam or cam rod 10. In cross section the cam 10 can be seen to have a flat portion 11 corresponding to the closed position of the valve 5 and the curved remainder of the cam corresponds to the opening of the valve 5.

If an array of valves are provided on the moulding surface, these may be co-ordinated in operation by a series of cam rods 10 linked by link rods 12 as shown in Figure 2. Arrow 13 indicates a rose joint rod end used in one preferred arrangement although other arrangements will be apparent to those skilled in the art.

As the cam rod 10 (shown in Figure 3) rotates, the valves are lifted and opened by contact with the curved part of the cam. Biasing means 14 are further provided to reclose the valve as the flat portion 11 is rotated into contact with the base of the valve. The biasing means 14 could be for example belville washers, rubber inserts, leaf springs, or could simply be achieved by the reversing action of the opening means.

The spring biasing means 14 shown in Figure 1 is retained in place about the valve stem by a base plate 15 and washer 16.

The valve 5 is preferably seated into a profiled seat as shown in Figure 1, which may be provided as a separate element 8 or machined directly into the face of the mould tool itself.

preferably, this seat is tapered, as shown in Figure 1, but a variety of shapes could be used to suit the application. A valve bucket 20 is provided about the valve stem in at least one preferred arrangement shown in Figure 4.

The surface 9 of the valve 5 facing the article 1 to be moulded is preferably shaped to conform to the moulded shape of the article. Thus while it is shown as flat in Figure 1, other shapes are also envisaged depending on the article to be moulded. The shaping of the seat 8 can be adjusted as required for different valve surface shapes.

A sleeve 17 may be provided about the valve stem to locate and retain the valve.

Actuating means 18 are provided to actuate the opening means, comprising for example air cylinders, hydraulic cylinders, rotary actuators, solenoids, electric motors or hand levers.

Figure 5 shows one possible arrangement of an array of ejection apparatus wherein a gas or gases such as air is supplied through a manifold 21.

The use of the invention will now be described.

In use, once an article has been moulded in the mould tool, and the removable tool face 4 removed, the actuation means 18, such as a hand lever, will be operated to actuate the opening means and open one or more valves 5 in communication with the moulding surface 6 retaining the moulded article 1. As the valve opens, a gas or gases such as air, optionally also including liquid mould release agent in atomised form, is passed through the gas feed passage 7 and pushes on the under side of the moulded item 1. Additionally, the projecting valve head surface 9 exerts physical force against the moulded article 1 to break its seal with the moulding surface 6.The gas pressure and/or physical force begins to eject the moulded item 1 from the mould surface 6, and as the valve further opens and the article is pushed away, and as further gas is passed through the gas feed passage 7, a build up of pressure over an increasing free area of the article 1 will occur, resulting in the demoulding of the article 1.

Once the article 1 has been fully ejected and cleared from the mould tool, the actuation mechanism 18 is reversed, and the valve 5 returns to the rest or closed position, by way of the biasing means 14, such as a spring, belville washer, or the like. Once in the closed position, the valve is sealed and gas cannot flow through the air feed passage 7. During moulding itself, the moulding pressure helps to ensure that the valve remains sealed.

Thus it can be seen that an apparatus and/or a method for ejecting a moulded article from a mould tool is provided by the invention, which is capable of achieving clean and rapid demoulding of a moulded article in a range of mould tools and mould techniques, which is simple to actuate, and ensures minimum interference with the moulded article which is ejected by air pressure.

Claims

WHAT WE CLAIM IS:

1. An apparatus for achieving ejection of a moulded article from a mould tool comprising: a valve in communication with a moulding surface of said mould tool; gas feeding means in communication with said valve; said valve when open allowing passage of gas from said gas feeding means to said moulding surface, and when closed preventing such passage of gas; opening means to open said valve; and biasing means to reclose said valve.

2. An apparatus as claimed in Claim 1, including liquid supply means to supply an external liquid mould release agent through said gas feeding means.

3. An apparatus as claimed in Claim 2, wherein said liquid supply means comprises an in-line atomiser.

4. An apparatus as claimed in any one of the preceding claims wherein said valve when closed is seated into a profiled seat in said moulding surface, and when said valve is open at least part of the valve mechanism projects from said moulding surface.

5. An apparatus as claimed in any one of the preceding claims including a valve bucket about the stem of the said valve.

6. An apparatus as claimed in Claim 4 wherein said seat is tapered.

7. An apparatus as claimed in any one of the preceding claims comprising an array of said valves.

8. An apparatus as claimed in Claim 7 wherein a series of cam rods linked by link rods are provided to open the valves of said array in a co-ordinated manner.

9. An apparatus as claimed in any one of the preceding claims wherein the surface of said valve facing the article to be moulded is shaped to conform to the moulded shape of said article.

10. An apparatus for achieving ejection of a moulded article from a mould tool substantially as hereinbefore described with reference to any one or more of the accompanying drawings.

11. A mould tool including one or more apparatus for achieving ejection of a moulded article from said mould tool according to any of the preceding claims.

12. A method of ejecting a moulded article from a mould tool, comprising the steps of: opening one or more valves in a moulding surface of said mould tool; passing a gas or gases through said valve or valves towards said moulding surface so as to pass between said moulding surface and a moulded article thereon; reclosing said valve or valves once said article has been ejected from said tool.

13. A method as claimed in Claim 12 including the step of supplying an external liquid mould release agent to said moulding surface together with said gas or gases.

14. A method as claimed in Claim 12 or Claim 13 wherein said valve when opened projects from said moulding surface so as to contribute mechanically to ejection of the moulded article.

15. A method as claimed in any one of Claims 12 to 14 wherein an array of said valves is opened in a co-ordinated manner.

16. A method of ejecting a moulded article from a mould tool substantially as hereinbefore described with reference to any one or more of the accompanying drawings.