DE1017862B - Device and machine parts made of polyamides that are exposed to sliding bearings and sliding friction - Google Patents

Description

Device and machine parts exposed to sliding bearings and sliding friction from polyamides There are numerous publications known whose subject the processing or mixing of plastics with other substances. more organic or of inorganic origin. These are often called fillers, fillers or z. B. referred to as an amplifier. The purposes for which the combinations are made Plastics and other types of material are produced, are very different. For example, sawdust can be mixed with a condensation resin to make insulating bodies against: to preserve cold and noise. The reduction in strength plays a role here generally does not matter. Other combinations only serve the purpose of that to change the mechanical properties of plastics in a desired sense. So one has z. B. synthetic resin compounds reinforced by glass fibers and in this way very stable structures received.

Another goal of using combinations of the kind mentioned is the creation or modification of certain mechanical properties of Plastics, namely the storage or sliding properties. There are quite a few of well-known plastics that are used in the manufacture of rollers, gears, plain bearings., Shafts, cams, etc. can be used. In many cases, e.g. B. at higher Stress, however, the plastics are unsuitable for themselves. Numerous regulations have been given to remedy the situation; curable condensation products are said to be finely powdered with Substances such as quartz sand, fireclay powder or silicon carbide are filled; Sponge iron, which has already been used as a storage material for itself, is said to have better storage properties obtained by soaking it with synthetic resins; oil-holding bearings of higher strength obtained when synthetic resins are pressed with metal powders; also graphite, which is called solid lubricant is known, phenolic resins have already been incorporated; mica is also known as a filler for plastics that are used to produce. Sliding surfaces be applied in the form of lacquers to metal substrates.

For some time now, polyamides have attracted particular attention. Because Their exceptionally favorable properties are increasingly being used in manufacture of bearings or machine parts that are subject to stress from sliding friction are used. For example there are bearing shells or treads in Bearings as well as shafts, journals and rollers made of polyamides. Also guides for machine parts, that perform a sliding movement can be made of polyamides. However, polyamides are not only used in mechanical engineering and instead of metals, but also in the exchange of wood, e.g. B. as guides or frames for sliding windows. In itself: the polyamides have very good properties for the purposes mentioned cannot be improved with the usual fillers. Some fillers improve the sliding properties, but reduce the strength of the Materials; with other fillers it is the other way round; some fillers, e.g. B. molybdenum disulfide, are very difficult to incorporate into polyamides.

It has now been found that sliding bearings and sliding friction are exposed to them Fixture, machine and guide parts with particularly favorable sliding properties and other mechanical properties obtained when filled with barium sulfate Polyamides used.

The advantageous properties of polyamides filled with barium sulfate It is especially surprising because graphite is known as a solid lubricant and which has already been recommended as a filler for polyamides, is not as effective is like barium sulfate.

Also the combination of Molybdenum disulfide and polyamides. the combination according to the invention is contrary to everyone Superior expectation. Molybdenum disulfide is already reduced in relatively small amounts Quantities the strength of polyamide parts. Usable mechanical values become at all only obtained with the expensive purified molybdenum disulfite. In contrast, improved Barium sulfate, even if it has been mixed in in large quantities, not just that The sliding properties of polyamide parts, but also their me: cha: -nic strength. For Polyamides suitable for the invention are prepared in the customary manner from aminocarboxylic acids or their inner acid amides obtained, e.g. B. from e-aminocaproic acid, w-aminocaprylic acid, 11-aminoundecanoic acid, e-caprolactam or w-capryllactam. The by polycondensation of diamines, for example hexa-, hepta-, octa-, decamethylenediamine or 4,4'-diaminodicyclohexylmethane, and dicarboxylic acids, for example adipic acid, Pimelic acid, suberic acid, sebacic acid or terephthalic acid, polyamides obtained. Any mixtures of polyamides as well as mixtures of the polyamide-forming ones Mixed polyamides made from substances can be used. As far as polyamides, z. B. in the usual way condensed e-caprolactam, larger proportions of low molecular weight, contain substances extractable by water or other solvents, it is in many cases it is advisable to extract these substances before further use. The production the polyamides or mixed polyamides are made in a known manner, with and without Addition of stabilizers, discontinuously and continuously.

The barium sulfate should be added to the polyamide in finely divided form be in which it z. B. as finely chopped, possibly specially purified Barite or, as chemically precipitated barium sulfate under the name Blanc fix, permanent white etc. is on the market.

The finely divided barium sulfate can be added to the monomeric polyamide-forming starting material during the condensation. But it can also in a known manner in the finished polyamide, for. B. be incorporated on the screw press. The products according to this invention can also be produced by sintering a mixture of polyamide powder and barium sulfate. The amount of de in the polyamide Coefficients of friction (coefficient of friction) with lubrication Coefficients of friction (coefficient of friction) with lubrication Exposure to water with machine oil 1 2 3 4 1 2 3 4 25 kg 0.30 0.24 0.20 0.24 0.16 0.16 0.12 0.16 50 kg 0.33 0.30 0.17 0.23 0.16 0.16 0.12 0.16 75 kg 0.27 0.24 0.18 0.21 0.16 0.16 0.12 0.16 100 kg 0.24 0.20 0.17 0.19 0.16 0.15 0.13 0.15 Deformation of the bearing in l / 100 mm with lubrication. Deformation of the bearing in l / 100 mm with lubrication with water with machine oil 25 kg 11 1 1 1 21 2 1 50 kg 21 15 10 13 35 18 13 15 75 kg 33 28 19 24 48 34 25 30 100 kg 47 44 30 36 63 49 40 45 The table shows that the bearings made of polycaprolactam with Blanc fix as an additive have considerably lower coefficients of friction and less deformation than bearings made of polycaprolactam without an additive and as bearings with graphite as an additive.

The use of graphite in addition to blanc fix primarily brings in water-lubricated polycaprolactam bearing shells are a further improvement. holding barium sulfate can be used within wide limits, e.g. B. between 3 to 60%, fluctuate. Additions of 5 to 30% have proven particularly beneficial. Admixtures from others Fillers, e.g. B. graphite, in addition to the barium sulfate are possible.

The polyamides containing barium sulfate can be used in various ways be brought into the form required for the intended use. By sintering in forms z. B. receive roles immediately. Bearing shells and guide rails can be made by injection molding or extrusion, possibly by machining Machining and grinding, made to measure.

If polyamide produced according to this invention is used for storage purposes, the use of lubricants is often recommended. Lubricating oils with and without the addition of molybdenum disulfide and water, aqueous solutions of glycols or other multi-valued. Alcohols come into consideration.

For the production of the filled polyamide masses and for the production no protection is sought for the plain bearing.

The advantages of this invention are evident from the table, their Values from comparative tests with test bearings in the Almen-Wieland machine (Archive for technical measuring V 9122 - December 9, 1951). The test bearings were made of polyamide from caprolactam.

In the table 1 = polyamide without additive, 2 = polyamide with 15 0 / o graphite, 3 = polyamide with 15% Blanc fix, 4 = polyamide with 7.5% graphite + 7.5% Blanc fix.

The deformation was found on the crosshead of the machine, which is at deformation of the bearing drops. This drop was measured with a micrometer measured. The condensate of a-caprolactam is usually about 9 to 10% extractables obtained. If you remove these, you get materials for bearings with even less deformation.

In the case of bearings made from a polyamide made from adipic acid or sebacic acid Hexamethylenediamine, the finely divided barite or Blanc fix alone. Or has been added as a mixture with graphite; surrendered values analogous to those listed in the table.

Claims (1)

PATENT CLAIM: Plain bearings and devices exposed to sliding friction and machine parts made of polyamides with a content of 3 to 60%, preferably 5 up to 30%, finely divided barium sulfate. Publications considered: German Patent Nos. 904 487, 901720, 898 831, 897 778, 853 067, 767 040, 698105 ; Patent No. 9950 of the Office of Invention in the Soviet. Occupation zone Germany; British Patent Nos. 695 195, 270 271; French patent specification No. 633 537.