GB2221644A

GB2221644A - A mould venting insert

Info

Publication number: GB2221644A
Application number: GB8819219A
Authority: GB
Inventors: Brian Ernest Purser; Ronald George Brown
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1988-08-12
Filing date: 1988-08-12
Publication date: 1990-02-14
Also published as: GB8819219D0

Abstract

A mould venting insert 14, which is located in a mould wall 10, has a central vent passage 18. In order to coat the walls of the passage 18 with release agent, an auxiliary passage is provided in the insert 14 so that the release agent can be introduced into the passage 18 between the ends of the passage. The auxiliary passage comprises a circumferential groove 20 in the outer face of the body 16 of the insert 14 and a plurality of radial bores 22 leading from the groove 20 into the vent passage 18. Release agent is fed to the groove 20 via a supply line 28 and a communication passage 24 formed in the mould wall 10. <IMAGE>

Description

A mould venting insert This invention -relates to a mould venting insert for mounting in the mould wall of a mould intended for the production of foamed plastics articles.

A venting insert of this type is required in moulds for foam articles to allow the release of the displaced air and of the gas evolved during foaming.

As part of the production process, it is conventional to apply a release agent to the internal cavity of the mould to facilitate release of the moulded article when moulding is complete. It is desirable for the release agent also to be sprayed onto the internal surfaces of the venting insert passage to prevent excess foam sticking to the walls of the passage.

According to the invention there is provided a venting insert for inclusion in the wall of a mould in which foam articles are to be produced, the insert comprising a body with a vent passage therethrough and an auxiliary passage leading from the outer face of the body into the vent passage to enter the vent passage between the ends thereof.

If the mould release agent is applied through the auxiliary passage, it is found that the internal surfaces of the wall are reliably coated with the agent.

The auxiliary passage preferably enters the vent passage midway between the ends of the vent passage to ensure that the whole of the vent passage is properly coated with release agent.

The insert body is preferably generally cylindrical, and the vent passage can extend axially through the body. The auxiliary passage can take the form of a circumferential groove in the outer face of the body together with a plurality of radial bores which lead from the groove into the vent passage; The invention also provides a mould for the production of foam articles, the mould including at least one socket in the mould wall for receiving a mould venting insert as set forth above, and a communication passage in the mould wall having one end positioned so as to communicate with the circumferential groove of an insert received in the socket, and the other end accessible from outside the mould for the introduction of release agent.

The end of the communication passage outside the mould wall may include a connector to allow release agent to be introduced through it. The introduction of release agent may be initiated and carried out automatically as a part of the moulding process.

The invention will now be further described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a cross sectional view through a mould wall incorporating a venting insert in accordance with the invention; and Figure 2 is a plan view in the direction of the arrow A of the mould wall and of the insert shown in Figure 1.

Figure 1 shows a mould wall 10 which has an aperture 12 forming a socket in which a venting insert 14 is fitted.

The insert comprises a body 16 with a vent passage 18 through it. The external cylindrical surface of the body 16 is threaded and is screwed into the socket 12. The insert has a circumferential groove 20 and four equiangularly spaced radial bores 22. The bores 22 lead from the circumferential groove 20 into the centre of the vent passage 18.

A communication passage 24 is formed in the mould wall 1Q adjacent to the socket 12 and has a connector 26 for connection to a release agent supply line 28. Release agent supplied through the line 28 is passed to the groove 20 and from there is distributed to the radial bores 22 and into the centre of the vent passage so that the walls of the vent passage can be properly coated with release agent.

In the absence of the auxiliary passages formed by the circumferential groove 20 and the radial bores 22, it would be necessary to introduce the release agent axially along the passage. If this is done, the back pressure which arises on spraying into a closed mould would prevent the release agent actually depositing on the walls of the passage.

The invention thus provides a simple modification to a vent insert which enables it to be properly coated with release agent so that the mould can be opened without difficulty after foaming.

Claims

1. A venting insert for inclusion in the wall of a mould in which foam articles are produced, the insert comprising a body with a vent passage therethrough and an auxiliary passage leading from the outer face of the body into the vent pasage to enter the vent passage between the ends thereof.

2. An insert as claimed in Claim 1, wherein the auxiliary passage enters the vent passage midway between the ends of the vent passage.

3. An insert as claimed in Claim 1 or Claim 2, wherein the body is generally cylindrical and the vent passage extends axially through the body.

4. An insert as claimed in Claim 3, wherein the auxiliary passage comprises a circumferential groove in the outer face of the body and a plurality of radial bores leading from the groove into the vent passage.

5. A mould for the production of foam articles, the mould including at least one socket in the mould wall for receiving a mould venting insert as claimed in Claim 4, and a communication passage in the mould wall having one end positioned so as to communicate with the circumferential groove and the other end accessible from outside the mould.

6. A mould as claimed in Claim 5, wherein said other end of the communication passage terminates in a connector to which a supply line can be connected.

7. A venting insert for inclusion in the wall of a mould, substantially as herein described with reference to the accompanying drawing.