Program-Controlled Apparatus for the Production of Moldings From Multicomponent Plastic, in Particular Polyurethane

The present invention relates to an apparatus for the production of moldings from multicomponent plastic, in particular polyurethane, this apparatus comprising a conveyor which mounts a plurality of interchangeable molds to be filled, a mixing unit for filling the molds, a mold release unit and a program control unit for controlling the conveyor, the mixing unit and the mold release unit.

The very large variety of such apparatuses are known. The conveyor is frequently a continuous conveyor in the form of a rotary table. The molds are filled at the mixing apparatus and emptied at the mold release unit. The latter is referred to as the robot. The molds must be exchangeable so that the apparatus can be used universally for the production of a very wide variety of moldings. The filling parameters, such as filling time, mixing ratio, mixing head setting and, where relevant, parting agent feed, must be reset for each mold. This is done by program control. Hence, for each mold there is a particular program which has to be selected in the appropriate computer for the mold mounted on the conveyor. In practice, an incorrect selection is frequently made, ie. the program selected is not intended for the mold present on the conveyor. This leads to incorrect operation and to rejects.

It is an object of the present invention to provide an apparatus of the type stated at the outset in which incorrect operation as a result of incorrect program selection is avoided.

I have found that this object is achieved if the apparatus also comprises a plug individual to each mold and connecting the associated mold with the program control unit, the plug having contacts which set up a code characteristic of the associated mold, and a decoder associated with the control unit, the decoder being responsive to the code for controlling the control unit to perform the program corresponding to the code.

According to the invention, program selection no longer takes place in the computer but virtually at the mold itself. By setting and coding the plug contacts, a code is fixed which corresponds to the appropriate program. In the decoder connected appropriately to the program control, this code is then converted to an appropriate signal to control the computer according to the program. This eliminates incorrect operation since the mold itself selects the program through the setting of the contacts. Furthermore, operation is simple since the plugs need only be inserted mechanically into the appropriate socket on the conveyor, after which the entire production takes place automatically.

An embodiment, shown schematically, is described with reference to a single FIGURE.

The apparatus, shown in plan view, consists of a control apparatus which in general is denoted by 1 and combines various functions.

The conveyor is in the form of a rotary table 2 possessing a drive 4. Various exchangeable molds 3 are arranged on the rotary table 2. Each mold is provided with a plug 10 which carries the coding cycles which can be set in a variety of ways. A mixing head is denoted by 8. This is supplied from a mixing apparatus 9 which Contains pumps, storage tanks, etc.

A mold release apparatus 5, referred to as a robot, removes the moldings from the mold and prepares them for the next shaping process. A parting agent can, if required, also be added here.

The program control unit 1 contains a decoder 6 and a program selector 7. As indicated schematically, these apparatuses control the foaming time (by means of unit 11), the mixing ratio (by means of 12), the mixing head setting and the subsequent mixing head program (by means of 13), the mold release apparatus and, where relevant, the parting agent feed (by means of 14), etc.

It can clearly be seen that, in this type of embodiment, it is virtually the mold itself which determines all the process steps required for producing its particular molding. Incorrect operation as a result of selecting the wrong programs cannot occur.