This invention relates to casting machines for insert moulding. Insert moulding is a known technique in which a moulded product is cast on or around an element (the "insert") placed in the mould tool.

The invention provides a casting machine for insert moulding, comprising a mould tool having a plurality of parts at least one of which is moveable between an engaged position where the tool is shut ready for a casting operation and a retracted position where the tool is open, the machine further comprising a mechanism for loading an insert into the tool preparatory to a casting operation, the insert loading operation being arranged to take place whilst the said moveable part of the tool is in its retracted position. By way of example, embodiments of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates a form of casting machine according to the invention, and

Figures 2, 3 and 4 show the insert loading mechanism in more detail, with parts of the machine removed for clarity. A casting machine for insert moulding is seen in the drawings. The machine comprises a main frame 10, upon which is mounted a mould tool 1 1. The mould tool 11 here is in four splittable parts that between them define a mould chamber: an upper part 11 a, which is mounted for reciprocal movement along a vertical axis, a lower part l ib, which is mounted for reciprocal movement along a first horizontal axis, and two side parts 11 c and 1 Id, which are mounted for reciprocal movement along a second horizontal axis, which lies at right angles to the first. As seen in the drawings, the lower tool part l ib is slideably mounted on two fixed pins 30a, 30b and its reciprocal movement is controlled by a pair of hydraulic rams 31a, 31b. The mould tool 11 is seen in Figure 1 in its shut position, i.e. with all of its parts 1 Ia, 1 Ib, 1 Ic, 1 Id engaged and ready for a casting operation.

The lower tool part 1 Ib is designed to hold an insert during the casting process, as will be described in more detail below. In the machine shown in the drawings, the part that is to be made is a conventional balance weight for a vehicle wheel. The insert needed for this is in the form of a channel-shaped clip formed from sheet steel, onto which is to be moulded a block of dense material, typically tungsten. The machine comprises a loading mechanism for placing the insert 12 on the lower tool part 1 Ib prior to each casting operation. The insert loading operation is arranged to take place whilst the lower tool part 1 Ib is in its retracted position. As it moves to its retracted position, the lower tool part l ib moves into engagement with a transfer head 16. A supply of inserts 12 is fed towards the transfer head 16 along a feed track 14. A stop mechanism 15 on the other side of the transfer head 16 is brought up into engagement with the endmost insert 12 on the track 14. This positions the insert 12 in the crook of a claw-shaped extension 17 on the lower tool part l ib. The insert 12 is held in this position by means of a latch 18 operated by a piston and cylinder device 19. This can be seen in Figure 5 (although this shows the lower tool part 11 b holding a finished part after a casting operation, ie insert plus weight, rather than a plain insert). Once the insert 12 has been positioned on and captured by the lower tool part l ib, this and the other tool parts are re- engaged ready for the next casting operation.

It will be noted that the insert loading operation is arranged to take place whilst the mould tool is split and at the location of the lower tool part l ib in its retracted position. This means that the loading operation can be synchronised with the usual splitting of the tool following a casting operation, saving time. It also means that the loading mechanism can be arranged apart from the mould tool casting process, facilitating its design and operation. It will also be noted that the insert loading mechanism is designed to be part of the machine. This enables the control of the loading operation to be fully integrated with the whole casting process. This is advantageous from the point of view of the design of the machine as a whole and its control programme, since the loading mechanism will operate on the basis of the same base data and degrees of movement as the rest of the machine. It is also advantageous from a process point of view, in that the timing of the loading and casting operations can be fully synchronised. In particular, the ability of the loading mechanism to be preparing for the next insert loading operation whilst the preceding casting operation is taking place allows the machine to be operated with maximum efficiency.

An important feature of the whole process is the fact that the insert is arranged to be mechanically positioned and held in place throughout the key steps of the casting operation. This is preferable to other more conventional means of insert handling, such as by gravity feed or compressed air, because it provides a greater degree of certainty as regards correct feeding and positioning, helping to minimise cycle time and reduce the chances of a malfunction.

Another advantage of the particular design and configuration of the machine is that it readily lends itself to adaptation. For example, it would be a relatively easy task to modify the insert loading mechanism to feed supplies of inserts from both sides of the transfer head, instead of just to one side, and thereby allow two parts to be made simultaneously in each casting operation. Indeed, this supply of inserts could be extended to include a bank of feed tracks to either side of the transfer head to allow the possibility of simultaneous casting of multiple parts.