DE2140917A1 - Low friction bearings - using a backed ptfe fleece to cover the bearing surface - Google Patents

Abstract

The bearing cover can be used for plain or ball bearings. A two layered fleece is used. The lower layer is made of a cotton fleece, which is covered by a PTFE fleece and the fleeces cross-stitched in known manner. The two-ply fleece is impregnated with a phenol resin and pressed onto the bearing surface with the PTFE layer uppermost.

Description

Method for producing a sliding or. Ball joint bearing Die The invention relates to a sliding or ball joint bearing with low frictional resistance.

Many devices require parts to rotate in a bearing shell. Figure I shows this case schematically. In a storage tray or in a bearing block 1, a piston rod 2 (shown in dotted lines) rotates (FIG. II shows a perspective view of the bearing block; Piston rod is not shown).

Since there is great resistance when rubbing metal on metal, lubrication is required. -But in recent times - especially with automobiles - more and more preference is given to lubrication-free bearings. You therefore have the surface, for example the bearing shell i covered with Teflon. Since the latter is a very smooth one surface the frictional resistance is already noticeably reduced. However, it is the application or incorporation of a compact Teflon coating - e.g. in the Offenlegungsschrift No. 1 425 998 described - difficult and in the bearing shell expensive.

It has therefore already been proposed that Teflon or polytetrafluoroethylene to be used in the form of fibers. In the magazine Kunststofftechnik, April 1971, page 151 under the heading: Less inspections on FIAT cars thanks to lubrication-free bearings that are "lined with Teflon't fibers".

Another proposal is to use Teflon fibers in the form of a double weave soaked with phenolic resin and then in the surface of a suitable plastic bearing press in. In this way it is already a satisfactorily working smear-free one Stock received.

It is also known, bearing shells by placing adjacent ones Yarns or threads, which are embedded in the surface of a resin, as plain bearings to use.

Surprisingly, it has now been found that the frictional resistance can be reduced again if you get into the surface of a bearing specially manufactured nonwoven fabric is incorporated.

As is well known, nonwovens are fiber fabrics, which are somehow connected to each other at their crossing points without weaving. According to registration a fleece made of Teflon fibers is now used. The latter is used as usual Soaked in synthetic resin and then pressed and incorporated into the surface of the bearing shells.

Since Teflon fibers are now expensive, according to the application one of two Layers of existing nonwoven fabric made. With the help of card and cross-layers For example, you prepare a cotton fiber fleece with a weight of 200 g / m2 one now leaves a Teflon fiber fleece (preferably with the fibers oriented lengthways) of only 20 g / m2. Then the two fleece layers are joined together needled in the usual way The needle technique is e.g. from Bayer Farbenrevue, 1962, No. 3, page 21 known. Then it is impregnated with a phenolic resin. Of the The resulting two-layer nonwoven is then applied to the surface of a bearing pressed on in such a way that the Teflon fiber layer points upwards.

If you should work with longitudinally oriented Teflon fiber fleeces the fibers should be attached in the direction of rotation of the shaft This type of lining of Storage with Teflon is much cheaper than all known methods 5 because much small amounts of fibers are required. In addition, the friction values Which in the plastics technology, page 251, in some cases still below.

In the above case, the weight of the Teflon fleece is only 20 g / m². Since such thin fleece is difficult to handle, it needs reinforcement. For this the cheap cotton fleece (preferably made with the cross layer) of 200 g / m2 is used. So there are practically all Teflon fibers used for Reduction of the sliding resistance used. One could of course also do a pure one Teflon fleece with over 200 g / m2 in the production of a bearing shell in the surface press in the same. In this case, however, most would be Teflon fibers are only required to achieve the stability of the fleece, but not to the Reduce sliding resistance.

Around the thin Teflon fiber layer with a thicker support fiber layer To connect, methods other than needles can also be used. So is the known work with binding fibers and subsequent calendering is possible.

In the case of a material produced by the method described above you can guarantee the sliding properties with a very thin layer of fibers, because they prefer to be on the surface and not like other materials are deeply embedded in the resin for good adhesion.

The production of the bearing shells or similar articles can be next after the already known pressing with precondensates, e.g. phenolic resin a method as mentioned in the laid-open specification No. 2 102 o86.

The fleece is soaked, for example, with caprolactam, polymerized, and can then then achieve the desired shape by pressing. Also is after This process enables the production of a cast bearing part from monomers.

In particular, this method can be used to fill the bearing parts with fibers reinforced, so that an even better impact strength is guaranteed.

Those used in the manufacture of the plain bearings according to the invention Nonwovens can also be produced as follows: First, on the steep sieve a hydroformer a layer of fibers, cotton, synthetic or ceramic fibers (aluminum silicate fibers) Floated in the usual process and then in the 2-substance system as a top layer of Teflon powder. The bond can be made with synthetic resins or polyvinyl alcohol.

This fabric is then briefly sprayed with phenolic resin or impregnated, dried and then pressed into bearing shells.

When using ceramic fibers as a substructure, it is also possible Teflon powder at a temperature of approx. 300 up to 400 C. sinter or soak the fleece with Teflon dispersion and then up to 4000C sintering on the PTFE and thus ensuring a good connection to the substructure.

Such surface finishes of bearing shells are in addition to the good ones Sliding properties still suitable to absorb very high temperatures.

Claims (1)

Claim Plain or ball joint bearings with low frictional resistance, thereby characterized in that in the surface of the bearing one consisting of two layers Non-woven fabric is incorporated, the fibers of the upper layer consist of Teflon. Blank page