Combination of a plasticising cylinder for a plastic mold machine with a feed hopper, said cylinder having amounting surface for engagement with said hopper, wherein said cylinder and said hopper carry cooperating projection and recess means and said combination further includes fastening means fastening said hopper to said cylinder, said fastening means beingconstructed and arranged to exert a force on said hopper along said mounting surface and said projection means being obliquely inclined to said mounting surface so that it exerts on said hopper a force having a component towards said mounting surface.

The invention relates to the combination of a plasticizing cylinder having a mounting surface with a feed hopper. The cylinder carries two pegs accommodated in corresponding recesses in the hopper. A threaded bolt is provided which is screwed through a portion of the cylinder and engages a surface on the hopper and exerts a force having a component along the mounting surface. The pegs are inclined to the mounting surface so that they exert on the hopper a force having a component towards the mounting surface.

In the past, hoppers have commonly been secured to their plasticising cylinder by means of threaded bolts projecting from the cylinder. Such an arrangement is relatively labour and time-consuming if a change of material or colour is to be made,since the hopper has to be removed and cleaned or replaced by another hopper.

It is also known to mount the hopper on a swivel arm and to use this arm to clamp the hopper against the plasticising cylinder. The work involved in assembling and dismantling the hopper for this is also considerable. In addition, theconstruction of the swivel arm is expensive.

It is an object of the invention to provide a simple means to enable rapid fastening of a hopper to a plasticising cylinder.

In accordance with the present invention there is provided a combination of a plasticising cylinder for a plastic mould machine with a feed hopper, the cylinder having a mounting surface for engagement with the hopper, in which the cylinderand the hopper carry a cooperating recess and projection and the hopper is fastened to the cylinder by means of a fastening device which exerts a force having a component along the mounting surface, the projection being obliquely inclined to the mountingsurface so that it exerts on the hopper a force having a component towards the mounting surface.

Thus the hopper may be clamped in the manner of a wedge between the mounting surface and the projection which is at an acute angle to the mounting surface. The projection produces a pressure forcing the hopper against the mounting surfacewithout it being necessary to introduce any external force at this location. Thus it is sufficient for the fastening device to engage the hopper at another location. Therefore the construction of the fastening device can be of simple design and thedevice can be constructed in such a way that it can be operated very simply in order either to release or lock the hopper.

Preferably the fastening means includes a bolt, e.g. a wing-headed bolt, inclined to the mounting surface and adapted to be screwed into a portion of the plasticising cylinder and to press against a surface on the hopper, which surface isconveniently at right angles to the axis of the bolt. By unscrewing the bolt the hopper can be simply removed or put in position.

In a preferred construction two projections or pegs are used with a single bolt between them. These are preferably arranged in the form of an isoceles triangle and results in the hopper exerting an even pressure on the cylinder and enables thehopper to be released or locked in a single operation.

The hopper is located on the plasticising cylinder by means of two projections projecting from the cylinder and received in corresponding recesses formed in the base of the hopper. The two pegs are spaced apart at one end and onopposite sides of a hole formed in the cylinder wall through which the interior of the hopper communicates with the interior of the cylinder. At the other end of the hole in the cylinder there is a mounting surface engaged by the base of the hopper.

The invention relates to a combination ofa plasticising cylinder for a plastic mold machine with a feed hopper, and is particularly concerning with the securing of a feed hopper to such a plasticising cylinder.