GB1565847A

GB1565847A - Apparatus for the manufacture of foamed plastics articles

Info

Publication number: GB1565847A
Application number: GB41853/76A
Authority: GB
Original assignee: Haendle & Soehne Maschf Karl
Current assignee: Haendle & Soehne Maschf Karl
Priority date: 1975-10-11
Filing date: 1976-10-08
Publication date: 1980-04-23
Also published as: FR2327070B3; ES452222A1; DE2545711A1; FR2327070A1

Description

(54) APPARATUS FOR THE MANUFACTURE OF FOAMED PLASTICS ARTICLES (71) We, KARL HANDLE & SÖHNE MASCHINENFABRIK UND EISEN GIESSEREI, a West German Kommanditgesellschaft, of 7130 Muhlacker, Industriestrasse 47, Federal Republic of Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to apparatus for the manufacture of foamed plastics articles, particularly polystyrene articles, comprising a mould having mould parts separable from one another, at least one mould part having a heating chamber connected thereto for receiving fluid heating medium, particularly a gaseous heat carrier, such as steam, to effect heating and foaming of plastics located in the mould cavity between said mould parts, and openings being provided in the or each said mould part which is provided with a heating chamber to permit passage of said heating medium from the associated heating chamber into the mould cavity.

For the manufacture of thin walled articles from expanded polystyrene with the above mentioned apparatus, a known procedure involves first of all closing the mould up to give a narrow gap between the two mould parts and then introducing foamable, suitably partially pre-foamed, plastics material into the mould. The mould is then closed and the heat necessary for the foaming of the plastics material and hardening of the article is fed to the plastics material by means of hot gas, in particular steam, introduced into two heating chambers connecting respectively with the mould parts.

The gas passes through the openings in the walls of the mould parts into the mould cavity. After the foaming of the plastics material the walls of the mould parts are cooled by means of a cooling system built into the heating chambers. For the separation of the mould parts and ejection of the formed article, compressed air is introduced into the heating chambers which compressed air reaches the mould cavity through the aforesaid openings in the mould parts and is blown onto the article so that this is lifted from the mould parts. In known apparatus used in this known procedure the disadvantage arises that residues from water remaining in the heating chambers are blown with the compressed air onto the finished articles and into the mould cavity. In consequence of the water drops collecting hereby in the mould cavity, filling faults arise when for the preparation of the next foaming procedure partially pre-foamed polystyrene is introduced into the mould. Such filling faults lead mainly in thin-walled articles, to waste.

In addition, the foamed articles must be dried in drying chambers or in heated zones for a long time in order to free them from the water residues admitted with the compressed air.

An object of the present invention is to provide apparatus with which these drawbacks can be avoided.

According to the invention therefore there is provided apparatus for the manufacture of foamed plastics articles comprising a mould having mould parts separable from one another, at least one mould part having a heating chamber connected thereto for receiving fluid heating medium to effect heating and foaming of plastics located in the mould cavity between said mould parts, openings being provided in the or each said mould part which is provided with a heating chamber to permit passage of said heating medium from the associated heating chamber into the mould cavity, and the or each said mould part which is provided with a heating chamber having at least one further opening therein connected to a duct for admission of compressed air for ejecting a formed article from said mould cavity on separation of said mould parts, the or each said further opening and duct being sealed relative to the associated heating chamber, and the or each said further opening being provided with a valve having a closure member which is spring urged to a closed position at which it engages a valve seat around the further opening so as to seal same whilst lying flush with the inner face of the pertaining mould part and is displaceable away from the further opening to permit escape of compressed air through the further opening to effect separation of the formed article from the mould part. With this arrangement it can be achieved that, in the case where water is present in the or each heating chamber, the compressed air does not take up any such moisture residue so that the mould cavity and the article can be kept dry. Advantageously the or each said further opening comprises a single bore in the pertaining mould part bounded by the associated said valve seat, so that the compressed air can, upon displacement of the valve closure member, pass directly into the mould cavity and lift and eject the formed article so that the removal of such article requires only a short time. In a preferred embodiment it is arranged that the closure member of the valve is formed as a valve plate and the valve seat is ground in so that a secure sealing of the mould cavity can be ensured.

The invention will now be described further with reference to the accompanying drawing which is a diagrammatic sectional view of one form of apparatus according to the invention.

The apparatus shown serves for the manufacture of thin walled articles 1 from foamed polystyrene and has two mould parts 2 and 3 determining the shape of the articles. These mould parts are placed against one another on their common separating joint 4 so as to enclose a cavity of the mould 5 to be filled with plastics for the foaming procedure.

Each of the two mould parts 2 and 3 is connected to an appropriate heating chamber 6 and 7 respectively. In these heating chambers steam can be introduced, as indicated with the arrows 8, in a usual manner.

Under the action of the steam, which can enter through a slit nozzle-like opening 9 into the cavity of the mould 5, the polystyrene located in the mould cavity foams.

After the foaming procedure the two mould parts 2 and 3 are cooled by a cooling system not shown. Then for the removal of the finished article the heating chamber 7 with the mould part 3 and the mould part 2 with its heating chamber 6 can be moved away from one another.

In order to be able to remove and eject the formed article easily from the mould without there being for the article the danger of damage, an inlet valve 11 is provided in the heating chamber 6 whilst in the heating chamber 7 two inlet valves 12 and 13 are arranged. These valves are connected to tubes 14, 15 and 16 respectively which are linked to a compressed air pipe system indicated by the arrows 17 and 18.

The pipes 14, 15 and 16 and inlet valves 11, 12 and 13 are sealed from the two heating chambers 6 and 7 such that the compressed air cannot enter the inner spaces of the heating chambers which receive the steam.

The inlet valves 11, 12 and 13 are built identical. In the following therefore only the inlet valve 11 will be described in detail.

The valve has a cylindrical bore 20 along which a spring loaded piston or guide member 21 can slide. This member 21 is connected via a piston rod 23 to a conical valve plate 24 serving as a valve closure member which valve plate is ground into its pertaining valve seat 25 around an inlet bore 26 of the valve which is coaxial with the bore 20. This inlet bore 26 extends through the mould part 2 and leads to the inner face of the mould part 2 and the arrangement and construction of the valve plate 24 is such that in the closed state of the inlet valve 11 (as shown) the front face of the valve plate 24 lies flush with the inner wall of the mould part 2. The valves 11, 12 and 13 are spring urged to the closed states thereof by means of the closure springs acting on the guide members 21.

If upon opening the mould, compressed air is fed to the inlet valves 11, 12 and 13 their valve plates 24 lift from the valve seats against the force of their closure springs.

The compressed air is released around the raised valve plates into the mould cavity and the formed article is lifted away from the inner faces of the two mould parts and is then ejected. Thus the removal of the formed article is completed. The pneumatic removal of the formed article protects the article against damage.

The tight closure of the compressed air system during the steaming and cooling of the article prevents the entry of water and steam into the air pipe system so that with pneumatic removal of articles no water sprays into the mould cavity and onto the article.

WHAT WE CLAIM IS: 1. Apparatus for the manufacture of foamed plastics articles comprising a mould having mould parts separable from one another, at least one mould part having a heating chamber connected thereto for receiving fluid heating medium to effect heating and foaming of plastics located in the mould cavity between said mould parts, openings being provided in the or each said

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. formed article from said mould cavity on separation of said mould parts, the or each said further opening and duct being sealed relative to the associated heating chamber, and the or each said further opening being provided with a valve having a closure member which is spring urged to a closed position at which it engages a valve seat around the further opening so as to seal same whilst lying flush with the inner face of the pertaining mould part and is displaceable away from the further opening to permit escape of compressed air through the further opening to effect separation of the formed article from the mould part. With this arrangement it can be achieved that, in the case where water is present in the or each heating chamber, the compressed air does not take up any such moisture residue so that the mould cavity and the article can be kept dry. Advantageously the or each said further opening comprises a single bore in the pertaining mould part bounded by the associated said valve seat, so that the compressed air can, upon displacement of the valve closure member, pass directly into the mould cavity and lift and eject the formed article so that the removal of such article requires only a short time. In a preferred embodiment it is arranged that the closure member of the valve is formed as a valve plate and the valve seat is ground in so that a secure sealing of the mould cavity can be ensured. The invention will now be described further with reference to the accompanying drawing which is a diagrammatic sectional view of one form of apparatus according to the invention. The apparatus shown serves for the manufacture of thin walled articles 1 from foamed polystyrene and has two mould parts 2 and 3 determining the shape of the articles. These mould parts are placed against one another on their common separating joint 4 so as to enclose a cavity of the mould 5 to be filled with plastics for the foaming procedure. Each of the two mould parts 2 and 3 is connected to an appropriate heating chamber 6 and 7 respectively. In these heating chambers steam can be introduced, as indicated with the arrows 8, in a usual manner. Under the action of the steam, which can enter through a slit nozzle-like opening 9 into the cavity of the mould 5, the polystyrene located in the mould cavity foams. After the foaming procedure the two mould parts 2 and 3 are cooled by a cooling system not shown. Then for the removal of the finished article the heating chamber 7 with the mould part 3 and the mould part 2 with its heating chamber 6 can be moved away from one another. In order to be able to remove and eject the formed article easily from the mould without there being for the article the danger of damage, an inlet valve 11 is provided in the heating chamber 6 whilst in the heating chamber 7 two inlet valves 12 and 13 are arranged. These valves are connected to tubes 14, 15 and 16 respectively which are linked to a compressed air pipe system indicated by the arrows 17 and 18. The pipes 14, 15 and 16 and inlet valves 11, 12 and 13 are sealed from the two heating chambers 6 and 7 such that the compressed air cannot enter the inner spaces of the heating chambers which receive the steam. The inlet valves 11, 12 and 13 are built identical. In the following therefore only the inlet valve 11 will be described in detail. The valve has a cylindrical bore 20 along which a spring loaded piston or guide member 21 can slide. This member 21 is connected via a piston rod 23 to a conical valve plate 24 serving as a valve closure member which valve plate is ground into its pertaining valve seat 25 around an inlet bore 26 of the valve which is coaxial with the bore 20. This inlet bore 26 extends through the mould part 2 and leads to the inner face of the mould part 2 and the arrangement and construction of the valve plate 24 is such that in the closed state of the inlet valve 11 (as shown) the front face of the valve plate 24 lies flush with the inner wall of the mould part 2. The valves 11, 12 and 13 are spring urged to the closed states thereof by means of the closure springs acting on the guide members 21. If upon opening the mould, compressed air is fed to the inlet valves 11, 12 and 13 their valve plates 24 lift from the valve seats against the force of their closure springs. The compressed air is released around the raised valve plates into the mould cavity and the formed article is lifted away from the inner faces of the two mould parts and is then ejected. Thus the removal of the formed article is completed. The pneumatic removal of the formed article protects the article against damage. The tight closure of the compressed air system during the steaming and cooling of the article prevents the entry of water and steam into the air pipe system so that with pneumatic removal of articles no water sprays into the mould cavity and onto the article. WHAT WE CLAIM IS:

1. Apparatus for the manufacture of foamed plastics articles comprising a mould having mould parts separable from one another, at least one mould part having a heating chamber connected thereto for receiving fluid heating medium to effect heating and foaming of plastics located in the mould cavity between said mould parts, openings being provided in the or each said

mould part which is provided with a heating chamber to permit passage of said heating medium from the associated heating chamber into the mould cavity, and the or each said mould part which is provided with a heating chamber having at least one further opening therein connected to a duct for admission of compressed air for ejecting a formed article from said mould cavity on separation of said mould parts, the or each said further opening and duct being sealed relative to the associated heating chamber, and the or each said further opening being provided with a valve having a closure member which is spring urged to a closed position at which it engages a valve seat around the further opening so as to seal same whilst lying flush with the inner face of the pertaining mould part and is displaceable away from the further opening to permit escape of compressed air through the further opening to effect separation of the formed article from the mould part.

2. Apparatus according to claim 1, characterised in that the or each said further opening comprises a single bore in the pertaining mould part bounded by the associated said valve seat.

3. Apparatus according to claim 1 or 2, charactensed in that the closure member of the or each valve is formed as a valve plate and that the associated valve seat is ground in.

4. Apparatus according to any one of the claims 1 to 3, characterised in that the or each valve has a cylindrical valve body which is coaxial with the pertaining said further opening.

5. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. An article when formed with the apparatus of any one of claims 1 to 5.