GB1575006A - Moulding of an article with a grooved bore - Google Patents

Description

(54) AN IMPROVEMENT IN OR RELATING TO THE MOULDING OF AN ARTICLE WITH A GROOVED BORE (71) We, PARAGON PLASTICS LIMITED, a British Company, of Cross Bank, Balby, Doncaster, 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 state menu : The invention relates to the moulding of an article with a grooved bore.and has for its object to provide an improvement therein.

According to one aspect of the invention, a method of moulding an article with a grooved bore includes the steps of locating an inflatable member in a groove in a core portion of a part of a die, causing an internal pressure to act within said inflatable member when contained in a cavity in another die part, whereby said inflatable member expands radially outwards of said groove to project partially into the mould cavity, injecting the mouldable material into the mould cavity so that it .surrounds the core portion and the radially expanded inflatable member, and subsequently releasing the internal pressure from within the inflatable member so that it is able to contract radially inwards to assume its former condition in which it is wholly located in the groove in the core portion to allow the core portion- to be withdrawn from the moulded article.

According to a further aspect of the invention, apparatus for moulding an article with a grooved bore includes a pair of die halves capable of being brought into abutment one with the other to define a mould cavity, a core portion arranged to project into the mould cavity to form the bore of the moulded article, and an inflatable member located in a groove in said core portion, means being provided for causing hydraulic fluid to act within the inflatable member whereby the latter can be inflated so that a portion of it is caused to protrude outwards into the mould cavity, release of said fluid from said inflatable member causing the latter to assume its former condition in which it is wholly located in the groove in the core portion. The core portion, which may be of cylindrical form, may-be carried by one die half and extend in the direction in which the pair of die halves are movable one towards the other. The core portion may abut against the bottom! of the mould cavity when the die halves have been brought together or may be spaced from the bottom of said mould cavity.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the drawings accompanying the Provisional Specification which are diagrammatic views which illustrate successive stages in the moulding of a synthetic plastics article in one form of apparatus embodying the invention.

Referring now to the drawings, Fig. 1 shows a pair of die halves, for the moulding of a synthetic plastics article, in open condition, that is to say a two part die half 10 provided with a cavity 12 and a die half 14 with a core portion generally india cated 16.

The cavity 12 is a cylindrical fiat bottomed cavity with an annular enlargement 18, as shown, and the die half 10 can be split in a plane containing the axis of the cavity. The core portion 16 which is to be entered into the cavity 12 includes an inflatable member 20 located in a groove.

Means are provided for causing hydraulic fluid, ducted through a supply conduit 22, to act within the inflatable member whereby the latter can be inflated so that, when the two die halves have been brought together as shown in Fig. 2, a portion of the inflatable member can be caused to protrude outwards into the mould cavity.

When the hydraulic fluid is released from within the inflatable member the latter returns to its normal size so that, as shown in Fig. 1, its outer periphery returns sub ;stantially to the size of the core portion.

The arrangement is such that, when the two die halves have been brought together and hydraulic pressure has been established within the inflatable member so that a portion of the latter has been caused to protrude radially outwards into the mould cavity as shown in Fig. 2, a synthetic plastics material can be injected into the mould cavity to produce an article S in the form of a generally cylindrical cap member with an external flange part which has been formed in the annular enlargement 18 and with a substantially half round groove within its bore which has been formed by the radially protruding portion of the inflatable member 20.

In Fig. 3 the die halves are shown to have been moved apart after the hydraulic fluid has been released from within the inflatable member, leaving the finished moulded article S within the cavity 12 of the die half 10 from which it can easily be removed by splitting said die half 10.

Various. modifications may be made without departing from the scope of the invention. For example, it will be understood that it is not essential for the core portion to be spaced from the bottom of the mould cavity when the two die halves have been brought together. It may abut against the bottom of the mould cavity so that the synthetic plastics article produced is in the nature of an open ended sleeve. Any kind of article which is to be moulded with a grooved bore may be produced by apparatus embodying the invention and of course it would be a simple matter to provide more than one groove in a bore if required, that is to say by providing more than one inflatable member in a core portion.

The selection of a suitable material for the inflatable member will present no great difficulty to those skilled in the art. On the other hand it may be found that the arduous working conditions in which the inflatable member is required to operate, that is to say arduous conditions of temperature and pressure, make it necessary to replace the inflatable member quite frequently. For this reason, the core portion may be made so that it can quickly and easily be dismantled for the replacement of the inflatable member.

WHAT WE CLAIM IS : - 1. A method of moulding an article with a grooved bore, the method including the steps of locating an inflatable member in a groove in a core portion of a part of a die, causing an internal pressure to act within said inflatable member when contained in a cavity in another die part, whereby said inflatable member expands radially outwards of said groove to project partially into the mould cavity, injecting the mouldable material into the mould cavity so that it surrounds the core portion and the radially expanded inflatable member, and subsequently releasing the internal pressure from within the inflatable member so that it is able. to contract radially inwards to assume its former condition in which it is wholly located in the groove in the core portion to allow the core portion to be withdrawn from the moulded article.

2. Apparatus for moulding an article with a grooved bore, the apparatus including a pair of die halves capable of being brought into abutment one with the other to define a mould cavity, a core portion arranged to project into the mould cavity to form the bore of the moulded article, and an inflatable member located in a groove in said core portion, means being provided for causing hydraulic fluid to act within the inflatable member whereby the latter can be inflated so that a portion of it is caused to protrude outwards into the mould cavity, release of said fluid from said inflatable member causing the latter to a;s.sume its former condition in which it is wholly located in the groove in the core portion.

3. Apparatus according to claim 2, in which the core portion, is carried by one die hall and extends in the direction in which the pair of die halves are movable one towards the other.

4. Apparatus according to claim 3, in which the core portion abuts against the bottom of the mould cavity when the die halves have been brought together.

5. Apparatus according to claim 3, in which the core portion is spaced from the bottom of the mould cavity when the die halves have been brought together.

6. A method of moulding an article with a grooved bore, substantially as hereinbefore described with reference to and as illustrated by the drawings accompanying the Provisional Specification.

7. Apparatus for moulding an article with a grooved bore, substantially as hereinbefore described with reference to and as illustrated by the drawings accompanying the Provisional Specification.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. inflatable member can be caused to protrude outwards into the mould cavity. When the hydraulic fluid is released from within the inflatable member the latter returns to its normal size so that, as shown in Fig. 1, its outer periphery returns sub ;stantially to the size of the core portion. The arrangement is such that, when the two die halves have been brought together and hydraulic pressure has been established within the inflatable member so that a portion of the latter has been caused to protrude radially outwards into the mould cavity as shown in Fig. 2, a synthetic plastics material can be injected into the mould cavity to produce an article S in the form of a generally cylindrical cap member with an external flange part which has been formed in the annular enlargement 18 and with a substantially half round groove within its bore which has been formed by the radially protruding portion of the inflatable member 20. In Fig. 3 the die halves are shown to have been moved apart after the hydraulic fluid has been released from within the inflatable member, leaving the finished moulded article S within the cavity 12 of the die half 10 from which it can easily be removed by splitting said die half 10. Various. modifications may be made without departing from the scope of the invention. For example, it will be understood that it is not essential for the core portion to be spaced from the bottom of the mould cavity when the two die halves have been brought together. It may abut against the bottom of the mould cavity so that the synthetic plastics article produced is in the nature of an open ended sleeve. Any kind of article which is to be moulded with a grooved bore may be produced by apparatus embodying the invention and of course it would be a simple matter to provide more than one groove in a bore if required, that is to say by providing more than one inflatable member in a core portion. The selection of a suitable material for the inflatable member will present no great difficulty to those skilled in the art. On the other hand it may be found that the arduous working conditions in which the inflatable member is required to operate, that is to say arduous conditions of temperature and pressure, make it necessary to replace the inflatable member quite frequently. For this reason, the core portion may be made so that it can quickly and easily be dismantled for the replacement of the inflatable member. WHAT WE CLAIM IS : -

1. A method of moulding an article with a grooved bore, the method including the steps of locating an inflatable member in a groove in a core portion of a part of a die, causing an internal pressure to act within said inflatable member when contained in a cavity in another die part, whereby said inflatable member expands radially outwards of said groove to project partially into the mould cavity, injecting the mouldable material into the mould cavity so that it surrounds the core portion and the radially expanded inflatable member, and subsequently releasing the internal pressure from within the inflatable member so that it is able. to contract radially inwards to assume its former condition in which it is wholly located in the groove in the core portion to allow the core portion to be withdrawn from the moulded article.

2. Apparatus for moulding an article with a grooved bore, the apparatus including a pair of die halves capable of being brought into abutment one with the other to define a mould cavity, a core portion arranged to project into the mould cavity to form the bore of the moulded article, and an inflatable member located in a groove in said core portion, means being provided for causing hydraulic fluid to act within the inflatable member whereby the latter can be inflated so that a portion of it is caused to protrude outwards into the mould cavity, release of said fluid from said inflatable member causing the latter to a;s.sume its former condition in which it is wholly located in the groove in the core portion.

3. Apparatus according to claim 2, in which the core portion, is carried by one die hall and extends in the direction in which the pair of die halves are movable one towards the other.

4. Apparatus according to claim 3, in which the core portion abuts against the bottom of the mould cavity when the die halves have been brought together.

5. Apparatus according to claim 3, in which the core portion is spaced from the bottom of the mould cavity when the die halves have been brought together.

6. A method of moulding an article with a grooved bore, substantially as hereinbefore described with reference to and as illustrated by the drawings accompanying the Provisional Specification.

7. Apparatus for moulding an article with a grooved bore, substantially as hereinbefore described with reference to and as illustrated by the drawings accompanying the Provisional Specification.