DE559153C - Injection molding machine with device for opening and closing the molded parts - Google Patents

Description

Injection molding machine with device for opening and closing the molded parts Injecting the molten metal into the mold by injection molding machines has so far been done by plunger or directly on the liquid level acting gaseous pressing agents. It is also already known to take the plunger instead to be controlled by hand by means of gaseous pressure medium, so that the fluid is not immediately can act on the metal.

Finally it has already been suggested that this should be the case for injection molding machines To cause the molded parts to close by hydraulic pressure and then this Increase pressure to keep the molds together during the injection molding process to secure.

Compared to this known method, there is now the novelty of the invention in a device in which to open and close the moldings and to Controlling the piston of injection molding machines using liquid pressure media namely according to the invention to achieve the hydraulic pressure is a multi-stage Press pump of the known type provided, the pressure levels with the to be moved Parts of the machine are connected by pressure lines running through into the latter as well as multiple control valves built into the discharge lines open and closed can be.

Such a device for opening and closing the mold parts as well as for controlling the piston of injection molding machines is on the drawing in a exemplary embodiment shown schematically. P is a three-stage hydraulic press pump for high, medium and low pressure. B1 and B2 are two pressure cylinders, in which the pump pistons K1 and K2 for moving the core and molded parts on the one hand and the actual - not shown - piston for pressing in the metal are stored in the mold.

The press cylinder B1 is connected through the lines a, b and the press cylinder B2 through the lines c, d on the one hand to the press pump P and on the other hand to the waste water tank W. A quadruple control valve s1 and s2 is switched on in each of the two line pairs a, b and c, d. Line b and line c are connected to the common line g which unites all three pressure stages of the pump. In this line g, a check valve R is arranged between the high pressure stage on the one hand and the medium and low pressure stage on the other hand.

At the beginning of the pumping process, the three pressure stages initially work together, so that the piston K of the press cylinder B1 is moved forward via line a and the molded parts are closed and held in the closed position. As soon as a certain pressure is now present in the line d, b , the check valve R closes, so that now only the molded parts are held in the closed position by the high pressure stage, while the medium and low pressure stages work together for themselves after the appropriate setting of the control valve s2 to drive the piston K. forward via the line d, which piston serves to move the actual - not shown - injection-molded piston.

The use of press pumps to open and close the core and Molded parts and for controlling the plunger of injection molding machines have advantages both on the operational side and on the economic side. Because when using gaseous pressure media, procurement is more expensive Air compresses are necessary while using liquid pressure media in place of the air compressor the cheaper press pump occurs. The harmful one is also known Influence of some gases on the metal level of the melt, for example oxygen the air on aluminum. So you are in the use of gaseous pressure medium forced either to accept these adverse effects, or to accept Instead of using a much more expensive inert gas instead of air.

In the case of the manually or mechanically controlled by means of a lever linkage Pistons and molded parts are one more or less dependent on skill and reliability of the worker operating the machine, quite apart from the fact that through manually or mechanically controlled pistons never use the high inflow velocities and strong pressing pressures can be produced than by means of liquids influenced plunger.

Claims (2)

CLAIMS: i. Injection molding machine with device for opening and Closing the molded parts and controlling the pressure piston by means of liquid pressure medium, characterized by a multi-stage press pump (P) of a known type for generating of the hydraulic pressure on the piston, whose pressure levels with piston (K1, K2) for moving the molded parts on the one hand and the injection-molded piston on the other hand Lines with switched on multiple control valves (s1 and s2) are connected. 2. Injection molding machine according to claim i, characterized in that in which to the individual pressure stages of the three-stage pump (P) subsequent common Branch pipe (g) of the pressure line between the high pressure stage on the one hand and the Medium and low pressure stage, on the other hand, a check valve (R) is installed, so that initially all pressure levels together close the moldings and cause the setting of the mold cores while after a certain amount has been reached Pressure the check valve (R) closes and consequently through the The high pressure line (g) alone holds the molded parts and cores in the closed position and through the medium and low pressure stage of the plunger (K2) to move of the injection molding piston is set in motion.