DK151708B - FORMULA LIST FOR SUPPORTING TRANSPORT CHAIN CHAIN - Google Patents

Description

DK 151708B

The present invention relates to a wear strip for sliding support of conveyor chains with plastic chain links. In such conveyors, it is necessary that the conveyor chain slides on special wear moldings, which are ideally partly durable, partly non-abrasive on the chain and partly allow the loaded chain to be conveyed with low friction, and the wear moldings should of course be stable and reasonable. affordable. Chain conveyors are used extensively in the industry and very large sums of 15 have been sacrificed on the development of suitable wear moldings, but the result has not been quite satisfactory so far.

The development so far has resulted in the use of moldings of either stainless steel, polyethylene or nylon, predominantly.

In the use of stainless steel, to achieve a low friction, it is necessary to lubricate the wear or slip strips, e.g. with water, which in itself is inconvenient. Further, it turns out that after some time, the steel material emits black particles, which with the water run down the tractor porter frame onto the floor, which is unacceptable especially in the food industry.

Plastic moldings do not need to be lubricated, ie they are applicable partly in general and partly where the goods are to be handled in dry conditions

DK 151708B

recitations. Here, polyethylene is the preferred material. This material is excellent in the case of an environment in which no dust or particles of impurities occur, but this condition is not met by the majority of conveyor installations, and it is quite common experience that the plastic chains wear out quite quickly. in most carriers. Admittedly, the sliding moldings are very abrasion resistant, but the overall result is of course 10 poor if they give rise to a pronounced wear on the transport chains. The explanation for this seems to be that the moldings of polyethylene exhibit such softness in the surface that dust and larger particles can be depressed in this to held positions in which the particles act as sandpaper against the moving chain.

As mentioned, Nylon has also been found useful in meeting the stated ideal requirements for wear molding material, but this view seems to be based on laboratory and not on practical matters. In practice, Nylon also tends to receive and retain in its surface particles, which then acts strongly on the plastic chain, just as Nylon is moisture-absorbing and is thus subjected to longitudinal extension of an elongated rail, itself gives rise to significant mechanical stability problems in practice.

Both polyethylene and nylon act as "surface-bleed" materials, and this has so far been found essential to achieve a low friction against plastic chains of transport, usually consisting of an acetal material.

DK 151708 B

However, it must be noted here that the softness in question accounts for a highly undesirable partial result, namely that after a short period of use the wear list is in practice transformed into a regular grinding element for the moving transport chain.

The invention is directly based on this observation and the characteristic therefore consists in that the wear molding consists of a preferably injection molded material of polyester or a similar surface hard plastic material, the surface hardness of which is greater than the surface hardness of the chain links. It is found that the use of such a surface-hard material can provide a desired low friction by cooperating with the usual plastic chain joints and, in addition, exhibits the essential property that foreign particles cannot or cannot, under extreme conditions, be pressed and held in the surface of the material so that the said sandpaper effect can be avoided in practice.

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The wear strips used so far have in practice been produced by sawing out pre-made plastic blocks, which inevitably has led to saw grooves and thus associated irregularities on the surface of the sliding strips. Such irregularities are, in so far, not essential for the general friction between the transport chain and the sliding strips, but they are essential for the total friction in that they promote the possibility of retention and collection of 30 impurities that easily accumulate in the bottom areas of the irregularities in the wear molding surface.

Against this background, it is a particular advantage that the irregularities in the material surface can 4

DK 151708B

is countered by the wear molds appearing as composed of injection molded wear molding elements, whereby the parts can be produced with a very high degree of surface smoothness, so that the surface does not act locally on impurities.

A further substantial improvement according to the invention can be achieved by the fact that, as indicated in the characterizing part of claim 2, a certain amount of glass particles are incorporated in the hard plastic material 10, which increases the strength and the surface hardness. That in itself is no new recognition as far as the material is concerned, since fiberglass reinforced polyester is very well known, but in this context there is no reason 15 to use a reinforcing reinforcement as the strength of the unarmed material will already be fully sufficient for the purpose. Thus, the glass particle admixture is used specifically for the purpose of increasing the surface hardness without any weakening of the properties which the material should otherwise exhibit just for use in slides of the kind in question. It is hereby considered only a fortunate fact that, for quite different purposes, an injection moldable polyester material having a content of glass particles which is also applicable for this purpose has already been developed, since it is found that with such a material it can be made extremely advantageous. wear molds for cooperating with chains of thermoplastic plastic, regardless of the material being developed for completely different purposes.

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Furthermore, it will be possible according to the invention to counteract an attachment to foreign particles on the wear list by the fact that in the material of the invention there may be mixed wax or oil, e.g. i 5

DK 151708B

in the form of so-called masterbats, which will generally act as friction-reducing also in terms of friction between the foreign particles and the wear list. This wax or oil, like the glass particles, may be pre-mixed in the granular material which is the basis for the injection molding of the wear molds or these additives can be supplied by admixture in the pure plastic granulate.

The glass particle mixture should be between 2% and 65%, while the wax or oil mixture should be between 1% and 30%.

It is essential for the invention that transport chains 15 with chain links of thermoplastic materials such as acetal work very well with plastic hard molds of surface hardness, e.g. of polyester, preferably with the addition of an additional hardness-giving particle material and an additional friction-lowering wax or oil material. In particular, in the preferred use of glass particles, but also in general, it is also essential that the wear molds be made by injection molding, whereby a well-smoothed surface product can be produced; Extrusion could also be an option, but the glass particle material would be hard at the extruder. In the case of injection molding, mold elements of reasonable length can be formed, e.g. 1-1.5 m, and the elements can hereby be easily manufactured directly with any necessary mounting holes and / or snap-lock parts as well as interconnecting parts, as well as they can be manufactured with desired processes and profiles, which will not need further explanation here.

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DK 151708B

Hard resins such as polyester also have the advantage of being form-stable; it is by the well-known and widely accepted disadvantage of the plastic materials for the purpose so far developed that the wear molds extend under the influence of tensile friction from the chain and that this causes special maintenance problems. Other forms of deformation have also been observed, but neither stretches nor warps will occur to any appreciable degree 10 by the use of polyester or similar materials, which, moreover, are also distinguished by not being water-absorbent.

The invention therefore solves virtually all the problems associated with the use of the most advanced wear moldings to date. Moreover, the invention offers the added advantage that the wear moldings according to the invention can generally be designed with less thickness than the known ones, e.g. 1 mm to 3 mm, which of course requires considerable material savings. In addition, it should be mentioned that the wear molding according to the invention can be fastened by adhesion much easier than the known molding moldings. In the injection molding it is possible to produce even very thin strips, e.g. with a thickness of approx. 0.2 mm, and such very thin moldings are suitable for attachment by adhesive.

Claims (3)

1. Plastic molding strip for sliding support of conveyor chains with plastic chain links, e.g. acetate, characterized in that the wear molding consists of a preferably injection molded material of polyester or a similar surface hard plastic material, the surface hardness of which is greater than the surface hardness of the chain links. 10 Wear molding according to claim 1, characterized in that the material has a glass particle content in an amount of 2-65% by weight. Wear molding according to claim 1 or 2, characterized in that the material has a content of 1-30% wax or oil, preferably supplied in the form of so-called masterbats.