GB2377667A

GB2377667A - Injection moulding

Info

Publication number: GB2377667A
Application number: GB0117492A
Authority: GB
Inventors: David Ganeshmoorthy; Kandiah Ganeshmoorthy; Richard Ganeshmoorthy
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-18
Filing date: 2001-07-18
Publication date: 2003-01-22
Also published as: GB0117492D0

Abstract

A plastic injection moulding process comprises steps of: introducing into an injection moulding machine a mould 14,15 defining a cavity (42) (figure 1, not shown); maintaining the mould 14,15 in an open configuration; mounting on a carrier 18 one or more components A,B,C,D to be shrouded, to a greater or lesser exten in a plastics material; the carrier 18 being movable between a support configuration (figure 3) wherein the or each component A,B,C,D is secured by the carrier 18 in a rigid configuration and a release configuration (figure 2, not shown) wherein the or each component A,B,C,D are released from being secured by the carrier 18 and exposed for removal from the carrier 18; mounting the carrier 18 while in its support configuration in the mould 14,15 in its open position; driving the mould 14,15 into a closed configuration housing the, or each, component A,B,C,D at a predetermined location within the closed mould 14,15 so as to cause the carrier 18 to be secured in place within the mould 14,15 and to define a plenum V for plastics material about the, or each, component A,B,C,D; injecting plastics material into the or each plenum V; allowing the plastics material to solidify; causing the mould 14,15 to move from its closed configuration to its open configuration; causing the carrier 18 to move from its support configuration to a release configuration; and removing the component A,B,C or D or components A,B,C,D from the carrier 18. The carrier 18 includes a rack member 19 and a trapping member 22 movably attached to member 19 for movement between the support and release configurations. Means are provided for the carrier 18 to be located in a mould cavity (42).

Description

INJECTION MOULDING This invention relates to injection moulding. In particular it is concerned with facilitating encapsulation of a fabricated component with a plastics material.

Injection moulding is a process for manufacturing parts in which a heated plastic is forced under pressure into a mould cavity which is complementary in shape to that of the part. The cavity having filled the injected plastic undergoes a phase change into a solid. Injection pressures can vary from 5,000 to 20,000 psi and in view of the high pressures involved the mould has to be clamped shut during injection and cooling.

Clamping forces required for this purpose are measured in tons. Tools used in such moulding processes are manufactured to high levels of precision and need to be sufficiently robust to stand repeated use in the moulding process. Typically moulds are of steel but can be, for example, of an aluminium alloy.

According to a first aspect of the present invention there is provided a plastic injection moulding process comprising the steps of: introducing into an injection moulding machine a mould defining a cavity; maintaining the mould in an open configuration; mounting on a carrier one or more components to be shrouded, to a greater or lesser extent, in a plastics material; the carrier being movable between a support configuration wherein the or each component is secured by the carrier in a rigid configuration and a release configuration wherein the or each component are released from being secured by the carrier and exposed for removal from the carrier; mounting the carrier while in its support configuration in the mould in its open position; driving the mould into a closed configuration housing the, or each, component at a predetermined location within the closed mould so as to cause the carrier to be secured in place within the mould and to define a plenum for plastics material about the, or each, component;

injecting plastics material into the or each plenum; allowing the plastics material to solidify ; causing the mould to move from its closed configuration to its open configuration; causing the carrier to move from its support configuration to a release configuration; and removing the component or components from the carrier.

According to a second aspect of the present invention there is provided a carrier for use in an injection moulding machine for an injection moulding process comprising: a rack member defining a first location to receive one extremity of a component, or of an extremity of each of two or more components; and a trapping member defining a second location for another extremity to the one extremity of a component or of each component in the case of two or more components; the trapping member being movably attached to the rack member for movement between: a closed configuration in which the rack member and the trapping member are juxtaposed to retain by way of the first and second locations in conjunction the, or each, component against movement relative to the carrier; and an open configuration position in which the rack member no longer serves to retain the, or each, component as aforesaid; and means providing for the carrier to be located in a mould cavity so that a component or components retained in the carrier while in a closed configuration can be accurately aligned in a plenum defined between the or each component and an adjacent region of the mould cavity. Typically the carrier provides that the first and second location involve a region of a component mounted on the carrier when in its closed configuration which region is not to be the subject of a subsequent coating process when the carrier is mounted in a mould cavity.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings of an injection moulding process of which: Figure 1 shows diagrammatically a working head of an injection moulding machine with a mould in an open position; Figure 2 shows a carrier for use in the machine of Figure 1 with the carrier in an open position; Figure 3 shows the carrier of Figure 2 but with its components in a different relative position; Figure 4 shows the working head of Figure 1 with the carrier of Figure 3 located in position; and Figure 5 shows a component partially encapsulated by the process described in connection with Figures 1 to 4.

Figure 1 shows part of a moulding machine 11 with two mounting plates 12,13 for, respectively, a mould half 14,15. The plate 12 and its associated mould half 14 can be driven towards static plate 15 (with its associated mould half 15) by means of a hydraulic ram system of which only a part of ram arm 17 is shown. Plastics material is injected into the closed mould halve s 14,15 (as shown in Figure) by way of inlet S through sprue S'.

Figures 2 and 3 show a carrier 18 for use in conjunction with mould halves 14, 15 so as to be able to locate accurately within the mould halves 14,15, at least when the mould halves are driven into their closed position as shown in Figure 4.

The carrier 18 is made up of a rack 19 made up of an U-shaped frame with side frame 19A, 19 B and a base frame 19C on which are mounted four projecting stems 20,21, 22,23 to provide, respectively, a sequence of four hollow first locations 24 to 27 which each serve to receive one extremity, respectively extremities 28 to 31, of four components A to D (See Figure 5) which are each to be provided with a cap of plastics material (shown in outline) by an injection moulding process involving the carrier 18 to be briefly described hereafter.

The carrier 18 has pivotably attached to it a trapping member 32 so that trapping member 32 can pivot about axis X between a closed configuration as shown in Figure 2 and an open configuration as shown in Figure 3.

The trapping member 28 provides four second projecting stems 33 to 36 to receive another extremity 37 to 40, of the components A to D, as shown in Figure 2, to enable the components to be held in alignment and securely in place during an injection moulding process when the carrier 18 loaded with the four components A to D is located accurately within closely specified tolerances within cavity 42 in closed mould halves 14,15.

Figure 5 shows component A which in this cases is an antenna unit 51 for a mobile phone comprising a insulating core 52 around which a helical metal antenna 53 is wound. The lower end of the antenna 53 is connected to a stem 54 by means of which the antenna unit 51 is coupled to circuitry in an associated phone unit. Once subject to the injection process the unit 51 is provided with a shroud of the injected plastics material to protect the antenna 53.

With the carrier 18 in its closed configuration loaded with components A to D and located in place in the cavity 42 there is left a plenum volume V in the cavity corresponding in shape to the desired shroud to be moulded around the upper part of each component. The injection moulding step is then carried out to drive plastic material into the plenum volume V through sprue S'to fill the plenum volume V.

Once polymerisation of the injected plastic in the plenum volume V has occurred the cavity 42 is then opened by driving the mould halves 14,15 apart to reveal the carrier 18 with the components A to D now each shrouded with the required moulding. The carrier 18 is then withdrawn and the trapping member 28 is hinged about axis X from its closed to its open configuration. The components A-D are then readily removed to enable to the carrier to be re-loaded and the moulding cycle to be repeated.

The use of carrier 18 with its ability to be opened and closed considerably facilitates the production of components involving a moulding step. The carrier provided for the accurate location of the components within a mould cavity to provide for accurate moulding to close tolerances of a complete component. Typically one involving a number of different materials.

In the exemplary embodiment the trapping member 28 is pivoted to the rack member 19 for simple rotation about axis X. However another linkage, or a combination of linkages, can be provided so that the trapping member can be moved relative to the rack member whether by angular rotation or linear displacement or combinations of these typically to provide for ready insertion of components into, and removal of components from, the carrier.

Claims

CLAIMS 1 A plastic injection moulding process comprising the steps of: introducing into an injection moulding machine a mould defining a cavity; maintaining the mould in an open configuration; mounting on a carrier one or more components to be shrouded, to a greater or lesser extent, in a plastics material; the carrier being movable between a support configuration wherein the or each component is secured by the carrier in a rigid configuration and a release configuration wherein the or each component are released from being secured by the carrier and exposed for removal from the carrier; mounting the carrier while in its support configuration in the mould in its open position; driving the mould into a closed configuration housing the, or each, component at a predetermined location within the closed mould so as to cause the carrier to be secured in place within the mould and to define a plenum for plastics material about the, or each, component; injecting plastics material into the or each plenum; allowing the plastics material to solidify; causing the mould to move from its closed configuration to its open configuration; causing the carrier move from its support configuration to a release configuration; and removing the component or components from the carrier.

<Desc/Clms Page number 7>
2 A carrier for use in an injection moulding machine for an injection moulding process comprising: a rack member defining a first location to receive one extremity of a component, or of an extremity of each of two or more components; and a trapping member defining a second location for another extremity to the one extremity of a component or of each component in the case of two or more components; the trapping member being movably attached to the rack member for movement between: a closed configuration in which the rack member and the trapping member are juxtaposed to retain by way of the first and second locations in conjunction the, or each, component against movement relative to the carrier; and an open configuration position in which the rack member no longer serves to retain the, or each, component as aforesaid; and means providing for the carrier to be located in a mould cavity so that a component or components retained in the carrier while in a closed configuration can be accurately aligned in a plenum defined between the or each component and an adjacent region of the mould cavity.
3 A carrier as claimed in Claim 2 wherein the carrier provides that the first and second location cover a region of a component mounted on the carrier when in its closed configuration which is not to be the subject of a subsequent coating process when the carrier is mounted in a mould cavity.