DE7244106U - Bushing for a twin screw housing of a plastic or rubber extruder - Google Patents

Description

our reference: 72 / 2'i Gbm

HERMANN BERSTORFF Maschinenbau GmbH

3 Hannover-Kleefeld

On the width V7iese 3/5

Bushing for a twin screw housing of a plastic or rubber extruder

The innovation relates to a bushing for a twin-screw housing a plastic or rubber extruder.

Plastics usually contain fillers, such as Pigments, which are mostly very hard and have a strong abrasive effect in the machine, i.e. very strong wear the inner surface of the bushing.

It is therefore the task of the innovation to provide double-son corner housings in which, in the event of wear, without major Cost that the socket can be replaced.

The new task according to tion is achieved in that in the twin screw housing of the extruder an exchangeable, massive bush made from one piece for the reception of the worms. which is not welded and is made of a highly abrasion-resistant material.

For a more detailed description of the prior art and the The innovation is referred to in the accompanying drawing.

In Figure 1, a Doppelschnecicen housing according to the state the technology shown, which consists of a cylinder and whose inner surfaces or running surfaces are nitrided. if Such a twin-screw housing shows signs of wear, the entire housing must be replaced, which is extremely costly.

In Figure 2 of the drawing, the wear bushings 2 are introduced by means of a hydraulic device. With so introduced wear bushing sn 2, however, it cannot be avoided on dom with 3 saddle points that there is a gap between the. forms both wear sleeves. This gap 3 ^at the saddle places, however, brings considerable night. Is suit sichi Σ-iner this nec-liir-eilc? assists in the fact that the gap becomes clogged with plastic in the course of time, the plastic burns in the gap and combustion residues from the gap more and more contaminate the plastic conveyed through the machine.

There is also the disadvantage that the ends forming the gap the connector bushings break out at their tips over time, Kodurch the gap 3 increases in an undesirable manner; the enlarged gap absorbs even more plastic and burns it, because of the possibilities of Contamination of the plastic by combustion residues increased even more than before, and also the Plastic is contaminated by metal particles broken off from the wear bushings.

Attempts have been made to remedy this disadvantage in that, as shown in FIG. H , the gap 3 has been welded shut. A permanent tight joint is, however, because of the

thermal expansion occurring during welding and the associated associated tensions cannot be achieved.

In Figure 3 of the drawing is also one of two parts ", . at the point 3 »welded solid cylinder shown, its Inner surfaces with an abrasion-resistant material, known under the trade name "Xaloy", are flung out.

< However, even when using this highly abrasion-resistant and

very expensive material "Xaloy" a sign of wear: the entire cylinder must not be excluded : be replaced in case of wear. It is easy to see that this possible solution is extremely costly; is playful.

• In Figure 5, a two-part solid cylinder is used: which is fixed by means of appropriate screw connections 2? Ue? (! * »! Tie?» G «linl". If there are signs of wear, the entire housing must also be replaced in this case With such a construction, the screw dimensions are also particularly disadvantageous, since the compressive forces that act on the screw connection are very difficult to determine.

It goes without saying that this solution is also very cumbersome and is therefore expensive.

The spraying of wear-resistant alloys onto the inner surface a twin-screw housing consisting of one piece is in principle also possible, but it works to the fact that there is only a relatively thin coating thickness on the cutting edge of the two overlapping cylinders can achieve. At the cut edge of the inner coating, which has to separate the material conveyed by the screws, however, considerable stresses occur, so that

the usual coating processes in this area a sufficiently strong and precise coating cannot be guaranteed, are unsuitable.

For this reason, you also have saddle-shaped edge bars in correspondingly designed, longitudinal recesses used inside the twin-screw housing, which are fastened in the block by suitable means.

The listening effort for this is, however, considerable, with the exact, dimensionally accurate installation of such saddle pieces is extremely cumbersome.

This is where the innovation comes in, which is shown in FIG. 6 of the drawing. A massive, exchangeable bush k , which is made from one piece and is not welded, is drawn into the double-clamp housing 1. Because the socket is not divided or welded, any difficulties in the saddle area are avoided from the outset. Further advantages lie in the precise manufacturing possibility with regard to the mean center distance and in the extremely low manufacturing costs. Should signs of wear occur despite the highly abrasion-resistant material of which the bushing is made, the bushing k is pulled out of the twin-screw housing 5 by known hydraulic devices and replaced with a new bushing.

By means of a measure according to the renewal, it is thus avoided that in the case of wear and tear on the inner surface of the socket entire twin-screw cylinder must be replaced. In addition, the disadvantages with regard to the The use of separate or welded bushings or with regard to inserted saddle pieces avoided.

Still further to be mentioned that it is advantageous particularly when not all of the twin-cylinder must be made of a highly abrasion-resistant material, ßrynnnm nvn- di f »einjezoiene socket ·. \ ν && leads to a substantial reduction in the cost of the extruder. .

- PROTECTION CLAIM -

Claims (1)

PROTECTION CLAIM Twin screw housing for a plastic or Gurruni extruder, characterized, that in the twin screw housing of the extruder a replaceable, massive bushing made from one piece for the reception of the worms, which is not welded and is made of a highly abrasion-resistant material. 724, 101 and 174