DE1778070A1 - Undivided elastic core bushing for the production of molded articles with undercuts - Google Patents

Description

Undivided elastic core bushing for the production of molded articles with undercuts The invention relates to the production of undivided elastic Core bushes for the production of such articles with internally pre-cut undercuts, which are made of pourable plastic or the like.

With such undivided core bushings made of elastic plastic, preferably a polyurethane elastomer, cuttings, i.e. articles, can be made with complicated undercuts, which previously only had multi-part metal cores could be produced.

In foundry technology, cores are known as lost cores Dezeicnnet, which are manufactured in molding sand or in the Groning process and are intended for single use only. In casting technology for castable plastics and resins, the above-mentioned cores are not to be used, multi-part none must be used here made of metal, but it is necessary to use the butt joints of the multi-part core to subsequently remove the sprouts on the article.

The invention is based on the task of manufacturing complex to switch off multi-part cores and subsequent cleaning work of the resulting To avoid sprouts.

According to the invention, this object is achieved in that the core bushing in one piece made of an elastic material, preferably a castable polyurethane elastomer is made, which bears elevations on the outside, the undercuts in the Pertigartikel form.

Undercuts, which are attached radially or at an angle to the axis are, according to a further embodiment of the invention, multiple times on top of one another be attached as an increase on the one-piece elastic core bushing, which are interconnected by a thin-walled cylinder.

Embodiments of the invention are shown in the drawing and are described in more detail below.

1 shows a one-piece core bushing according to the invention with several superimposed radially circumferential elevations or webs.

Fig. 2 Such a core bushing in section, installed in a casting mold for bearing bushes with three undercuts or grooves.

Fig. 3 A one-piece core bushing according to the invention in plan view with four axial elevations or webs.

FIG. 4 side view of FIG. 3.

Fig. 5 A one-piece core bushing according to the invention with spiral or thread-shaped circumferential elevations, which above and below in a radial elevation end up.

In Fig. 1, there are three in the side view of the one-piece core bushing Variants of the elevations or webs shown with b in square or rectangular Cross-section with c in a semicircular cross-section and with d in a triangular cross-section, which are homogeneously connected to the thin-walled socket a. This core socket like shown in section in Fig. 2, is pushed over a core bolt e and with this centered in the mold base plate f concentric to the mold plate g. The gap between the shaping contour of the mold plate g and the outer contours of the core bushing a, can be filled with pourable or thermoplastic plastic h.

When the finished article h is removed from the mold, the core bolt is e nerausgedräckt and removing the elastic one-piece core bunch according to the invention in that one with a stable, not too pointed single chain, aen the upper edge of the thin-walled one Press socket a inwards and follow it deeper with the tweezers to the middle of the Core bushing. By turning the tweezers to the left or right and at the same time Pull, the elastic elevations or webs jump out of the molded in the article Grooves and the elastic core bushing can be used for the next casting process.

A one-piece core bushing according to Fig. 3 + 4 with axial elevations or webs R are used, for example, to manufacture such bearing bushings for sliding movements in the axial direction.

According to the excerpt from fig. 5 you get bearing bushes with spiral oaer helical grooves m, which are not continuous over the entire length sid and above and below terminate in a radial groove b.

The advantages that can be achieved with the invention are, in particular, that in series production of such articles with undercuts such as seals and Bushings the expensive mold costs for multi-part metal cores are reduced, the demolding time through the elastic one-piece core bushings is shortened and the cleaning work of the shoots, as with multi-part metal cores, is no longer necessary.

The one-piece core bushings are cast in a master mold made, which can be in one piece due to the elasticity of the cast. Should For technical reasons, a multi-part mold to manufacture this one-piece If elastic core bushings are required, the external protrusions are cheaper to remove.

The bearing bushes shown in the exemplary embodiments with radial or undercuts running obliquely to the axis serve as lubrication grooves, whereby the production of such articles with undercuts has so far been a significant cost factor represented.

Claims (4)

Claims 1. Undivided elastic core bushing for manufacturing such articles with internal undercuts that were previously mechanical incorporated or manufactured using multi-part mold cores, characterized by dalM on a thin-walled cylindrical or conical core sleeve made of elastic castable plastic, preferably a polyurethane elastomer, are made with externally attached elevations or bars. 2. Undivided elastic core bushing according to claim 1, characterized gekennzeicnnet, that several elevations or webs are attached radially circumferentially one above the other, with square, rectangular, semicircular or triangular cross-section. 3. Undivided elastic core bushing according to claim 1, characterized in that that several non-continuous elevations or webs are arranged axially on the circumference are. 4. Undivided elastic core bushing according to claim 1, characterized in that that the elevations or webs are attached in a spiral or helical manner, which end in a radial elevation or web at the top and bottom.