Friction system
A friction system, including a plurality of friction elements which interact by way of contact surfaces for clutches of gearboxes or wheel brakes of motor vehicles. At least one friction element from the plurality of friction elements includes wholly or in part a composite material with high wear resistance and high heat resistance. The at least one friction element includes a carbonized plastics matrix mixed with frictionally active substances and strengthening fibers and a high-temperature-resistant friction matrix with stable friction properties and high wear resistance.
1 . A friction system, comprising at least two friction elements which interact by way of contact surfaces, preferably for clutches of gearboxes and/or wheel brakes of motor vehicles, of which at least one friction element consists wholly or in part of a composite material with high wear resistance and high heat resistance, wherein the friction element ( 9 , 10 , 15 , 20 , 21 ) is produced by carbonizing a plastics matrix mixed with frictionally active substances and strengthening fibers with the exclusion of oxygen and producing a high-temperature-resistant friction matrix with stable friction properties and high wear resistance.
2 . The friction system as claimed in claim 1 , wherein the friction element ( 9 ) takes the form of a type of annular disc ( 16 ).
3 . The friction system as claimed in claims 1 and 2 , wherein the friction element ( 9 ) of the annular disc ( 17 ) is produced from one piece.
4 . The friction system as claimed in claims 1 and 2 , wherein the friction system of the annular disc ( 18 ) comprises a core disc ( 19 ) with friction elements ( 20 , 21 ) attached thereto.
5 . The friction system as claimed in claim 1 , wherein substantially the following raw materials are used to produce the friction element ( 9 , 10 , 15 , 20 , 21 ):
resin
barytes
lamp black
preoxidized PAN fibers
glass fibers
6 . The friction system as claimed in claims 1 and 5 , wherein bronze powder is used to produce the friction element.
7 . The friction system as claimed in one or more of the preceding claims, wherein substantially the following raw materials are used to produce the friction element:
resin
barytes
lamp black
preoxidized PAN fibers
glass fibers
bronze powder
8 . The friction system as claimed in claim 7 , wherein Novolak powder resin is used as the resin.
9 . The friction system as claimed in one or more of the preceding claims, wherein the raw materials as constituents for producing the friction element are divided up as follows:
Novolak powder resin
approx. 20 vol. %
Barytes
approx. 20 vol. %
Lamp black
approx. 15 vol. %
Preoxidized PAN fibers
approx. 15 vol. %
Glass fibers
approx. 15 vol. %
Bronze powder
approx. 15 vol. %
10 . The friction system as claimed in claim 9 , wherein the glass fibers are 1 to 3 mm, preferably 3 mm, in length.
11 . A method of producing the friction element as claimed in one or more of the preceding claims, wherein the constituents are processed to yield a homogeneous mixture.
12 . The method as claimed in claim 11 , wherein the mixture with a suitable resin content is processed to yield a preform in a press tool using a defined press-molding method.
13 . The method as claimed in claim 12 , wherein the preform is precured during the press-molding procedure.
14 . The method as claimed in claim 12 , wherein the temperature during the press-molding procedure amounts to between 120° C. and 180° C., preferably 150° C.
15 . The method as claimed in one or more of the preceding claims, wherein the preform is treated by means of a curing process.
16 . The method as claimed in claim 15 , wherein the curing process for the preform proceeds at temperatures of between 220° C. and 280° C., preferably 250° C.
17 . The method as claimed in one or more of the preceding claims, wherein the preform is treated by means of carbonization.
18 . The method as claimed in claim 17 , wherein carbonization of the preform takes place by pyrolysis.
19 . The method as claimed in claim 18 , wherein pyrolysis takes place from 350° C. in an inert atmosphere.
20 . The method as claimed in claims 18 and 19 , wherein pyrolysis takes place at temperatures in the range from 400° C. to 600° C. and brings about conversion of the resin, preferably phenolic resin, into carbon.
21 . The method as claimed in one or more of the preceding claims, wherein the friction element treated using pyrolysis is finished by defined machining, e.g. drilling, grinding or the like.
22 . The method of producing the friction element as claimed in claims 1 to 8 , characterized by the following method steps,
Bringing together the raw materials into a mixture using a suitable mixing means,
Metering and press-molding the mixture to yield a preform using a suitable press-molding method,
Curing the preform in a forced air chamber kiln,
Pyrolysing the preform,
Machining the friction element produced e.g. by means of stamping, cutting, drilling, grinding or the like.