12 is greater than the pressure generated by the extruder 10 which is greater than the pressure generated by the cylinder 11. In this case, the cylinder 11 is filled while the cylinder 12 injects the material into the mould. Pressure control of the valves 15, 15′, 15″ is advantageous as it is very robust and allows the flow of material which is highly charged and homogeneous as regards the dimension of the fillers. Preferably, the valves 15, 15′ and 15″ are ball valves.

An alternative device consists in using valves 15 and 15″ controlled on opening such as piston valves.

The shutter 16 makes it possible to connect the injection device to the cavity of the mould when the mould is in the injection position. Conversely, when the mould is in the movement phase owing to the rotation of the barrel, the shutter 16 is closed and shuts off the injection channel of the moving barrel.

The distribution plate 17 is a fixed part of the device which ensures the transition between the hot part of the machine (injection device) and the cold part (barrel with the moulds). According to the invention, the moulds 41-52 slide on the distribution plate 17 during rotation of the barrel 21. Thus, depending on the angular position of a mould relative to the distribution plate, this mould is successively in the injection position (the distribution plate has a hole for the passage of the material through the injection point 20); then in the cooling position (the distribution plate obstructs the injection point 20 and closes off the cavity of the mould); then in the ejection position (the distribution plate has a hole for the ejection of the moulded item in the form of a profile). These different functions of the distribution plate 17 are made possible by the fact that the distribution plate 17 is fixed and that it is therefore the rotation of the barrel 21 that will place a mould in the correct position for injection, cooling or extraction of the moulded item.

Preferably, the distribution plate 17 undergoes a surface treatment to preserve surface hardness and allow sliding of the barrel 21. The treatment may for example be tempering, nitriding etc. or another equivalent treatment.

Consequently, the pressures in particular between the distribution plate 17 and the barrel 21 that will allow, on the one hand, injection without dripping of the material while at the same time allowing relative rotation between the distribution plate 17 and the barrel 21 without the material leaking from the filled mould 41, are defined according to embodiments of the present invention. Non-limiting examples are given below.

The moulds according to the invention are arranged in a barrel 21 preferably filled with water. Thus, there may be for example twelve moulds 41-52 arranged in the barrel. Upon each rotation of 1/12 of a revolution of the barrel 21, one mould is in the injection position, one mould is in the ejection position and the other ten moulds are in the cooling position. The advantages of moulds 41-52 arranged in a barrel 21 are multiple. The moulds 41-52 are very simple as they are cooled by immersion in the tank of the barrel 21 (no cooling circuit per mould). The barrel 21 and the moulds 41-52 form an assembly that may be changed very quickly on the machine. The time required to change a mould is therefore much reduced. It is also easy to increase or reduce the number of moulds on the barrel 21. Thus, for parts which are twice as small, there may be 24 moulds instead of 12 in the barrel. The optimization of the number of moulds in the barrel 21 makes it possible to use the device to its maximum extrusion capacity. Preferably, the number of empty moulds in the barrel will thus be limited, for example to one mould between ejection and injection.

The machine also comprises an extractor 18 and ejector pistons 19 for each mould 41-52.

The embodiments of the invention are distinguished from the prior art in particular by virtue of the following:

- The extruded material arrives via a single injection point 20 which is fixed and passes through the distribution plate 17. It is the moulds 41-52 that move (preferably by rotating) so as to be positioned facing the injection point 20 in order to be filled each in turn. The number of moulds is not limited, for example so as to be equal to the number of cylinders, but is independent. The moulds are placed in a barrel 21 which rotates and places each mould 41-52 of said barrel 21 successively before the fixed injection point 20. By virtue of this structure, the cooling time for the moulded article has no impact on the work rate of the machine and its operation may be optimized. The cycle of the machine only depends on the injection time and the time necessary to lower the pressure in the mould and allow the rotation of the barrel 21 so as to bring the next free mould 41-52 before the injection point 20.
- The mould 41-52 for injection-moulding a part consists of a movable part (the barrel 21 comprising the moulds 41-52 per se) and a fixed part (the distribution plate 17 with the injection point 20).

According to the invention, preferably, the distribution plate 17 is cooled, which makes it possible to set the threshold of the injected material 31 in the mould and facilitates the relative movement between the barrel 21 and the distribution plate 17.

The cooling means are for example a water circuit arranged in the distribution plate along the path travelled by the moulds.

According to the present invention, the position of the ejectors 19 may be used to measure the level of filling of the moulds 41-52. To be specific, when the mould is full, the pressure in the mould increases rapidly beyond the injection pressure, which leads to the formation of drips at the inlet of the mould on the same side as the injection point. Therefore, by measuring the position of the ejector 19 it can easily be determined when the mould is full (or at least nearly full) and thus prevent a sudden increase in pressure in the mould and the creation of said drips, by controlling the injection pressure, for example by stopping injection or reducing the injection pressure as a function of the state of filling.

FIG. 2 shows an example of a barrel 21/distribution plate 17 pair. In this FIG. 2, the left-hand drawing is a view of the distribution plate from the side of the moulds 41-52 (left-hand side of the plate 17 in FIG. 1) and barrel 21, and the right-hand drawing is a view of the distribution plate 17 from the other side, i.e. the same side as the injection nozzle 28 (right-hand side of the plate 17 in FIG. 1). FIG. 2 shows the barrel 21 comprising twelve moulds (41 to 52) and also shows the distribution plate 17 associated with the barrel