DE7418744U - Injection molding machine - Google Patents

Description

Patöntä'n'n'wälte Dfpl.-lng. Leo Fleuchaus , Dr.-Ing. Hans Leyh (I. Dipl.-Ing. Ernst Rathmann '

8 Munich 71, Melchiorstr. 42

Ludwig Engel KG in Schwertberg (Austria)

Injection molding facility

The innovation relates to a device for injection molding, in particular thermoplastic materials provided with a blowing agent Plastics, the pressurized plasticized plastic branching off from a common hot runner separate lines are supplied to several closable injection nozzles, in particular needle valve nozzles.

Injection molding thermoplastics with various blowing agents has recently become increasingly important, as it allows the use of relatively thin-walled molds that are only used to accommodate the in the order of magnitude of 50 atmospheres lying inflation pressure must be designed. The closing pressure of the injection molding machine can also be used during injection molding are kept comparatively low by thermoplastics provided with propellants.

Difficulties arise with the devices outlined at the beginning for the production of so-called structural foam by the fact that the injection pressure under which the plasticized plastic reaches the shut-off nozzles in the mold cavities is supplied, must be very high in order to prevent premature puffing of the mass. This pressure is on the order of magnitude from 200 to 800 atmospheres and it must be

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be prevented that it is fully effective inside the mold. "The mold must therefore be closed" before the internal pressure has approached the injection pressure in an impermissible manner. The plastic would just have a hollow shape over If only one injection nozzle was supplied, the problem could be solved simply by dosing the quantity. The situation is different if several injection nozzles are provided, to which the plastic is supplied from a common supply. Here the supply of a disproportionate amount of plastic to one of several mold cavities would be under Under certain circumstances, however, even one of several injection openings of a single cavity can destroy the shape to lead. To avoid this, a way must be provided, the ratio of the flow resistances in the vom precisely set common hot runner to the individual inlet nozzles lines. According to the innovation, it is therefore provided that that at least some of the lines are provided with adjustable throttles.

This measure ensures in a simple manner that only the fixed portion of the through each injection nozzle total supplied plastic is injected. When the operating conditions change, for example by switching off individual lines, change of the shape volume "increase of the Flow resistance.es through material deposition or the like. is Due to the adjustability of the throttles, a quick adjustment of the operating conditions is possible.

The innovation will now be explained in more detail with reference to the drawing. FIG. 1 shows a basic diagram and FIG. 2 shows an exemplary embodiment of an adjustable throttle according to the invention.

Lines 2, which lead to the injection nozzles 4, branch off from the common hot runner 1. The length of each line

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can be different in shape due to the arrangement of the injection nozzles 4, whereby different Resistance arise. This in turn can lead to uneven operation of the injection nozzles 4. For this Basically, 2 adjustable throttles 3 are built into the individual lines, with the aid of which there are 2 equal resistances in each line or the working characteristics of the individual injection nozzles 4, which mostly have a needle lock, adapted resistances can be achieved.

The throttle 3 according to the invention consists essentially of a bore running perpendicular to the line 2 pressed-in sleeve 31 and one in the sleeve 31 axially displaceable Bolt 32. The sleeve 3Ί points at the level of the Line 2 has a transverse bore 33 and is held down via a flange 35. The area protruding over line 2 the sleeve 31 is closed by a plug 34-.

The bolt 32 has a thread 37 which is in the threaded bore of the hexagon 36 is held. He can through the appropriate Rotation can be pushed more or less far into the sleeve, whereby the bore 33 of the sleeve 31 more or covered less far and thus the resistance of the throttle 3 is changed. The hexagon head 39 of the bolt makes turning easier and the scale 37 makes it easier to adjust the individual throttles 3 *

The hexagon 36 is screwed onto the sleeve 31 and has a transverse bore 40 through which any leakage material may occur can drain.

This construction of the throttle 3 makes it possible to easily replace bolts 32 which are glued through the bushed material. It is sufficient to unscrew the hexagon 36 from the sleeve 31 to its thread

practically no material can get in, and the bolt 32
to be pulled out and replaced by a new bolt 32 including hexagon socket 36. The removed bolt 32 can then be cleaned immediately after production
the replacement of the bolts 32 can be resumed.

Claims (2)

• ti (■ Protection claims: 1. Device for injection molding, in particular with propellant provided thermoplastic plastics, whereby 'the plasticized plastic under pressure over from Separate lines branching off a common hot runner, several closable injection nozzles, in particular Valve gate nozzles, is supplied, characterized in that at least some of the lines (2) with adjustable Throttles (3) is provided. 2. Device according to claim 1, characterized in that the throttle (3) consists essentially of a bolt (32), the end of which can be screwed into the line (2) perpendicular to the dxeser is.