DE10035489B4 - friction pairing - Google Patents

Abstract

friction pairing with at least one friction body and a counterbody, wherein at least one friction body from a basic body (2) and a friction lining (3), which is connected to the main body (2) is connected, characterized in that the friction lining (3) is a chromium-iron alloy, the 10 - 60 % Cr, 0.3-0.5 % C, remainder contains Fe and a strength of 10-200 μm.

Description

field of use the invention

The The invention relates to a friction pair with at least one friction body and a counterbody, wherein at least one friction body from a basic body and a friction lining, which is connected to the base body.

background the invention

Becomes Such a friction pair in synchronized shift or change gears used in motor vehicles, so when switching the on the shaft freely rotatable gear by axially pressing a synchronizer ring to a gear wheel associated with the coupling ring in synchronization with the Wave brought, the transmission the forces from a rotationally fixed on the shaft, but axially displaceable sliding sleeve over a axial or radial locking and / or Mitnehmerverzahnung on the synchronizer ring. Subsequently, will the gear by further axial displacement of the sliding sleeve, which then engages in a driver toothing of the coupling ring, form-fitting connected to the shaft. To achieve the synchronization between Synchronizer ring and gear, the synchronizer ring has außenkonische or internal conical friction surfaces on, in the axial pressing of the synchronizer ring with corresponding mating surfaces come in contact at the dome ring and by occurring friction to the Switching through the form-locking Coupling required synchronism produce. In addition, can in a so-called double-cone synchronization between them friction surfaces a friction ring may be arranged.

When known technical solutions are used in synchronizers, in which conical friction surfaces interact, Friction pairings used with different sliding friction materials, such as Special brasses, bronzes, molybdenum coated, oxide coated or multi-coated surfaces as well as plastics that against a hardened steel surface rub.

So is in this context from the DE 42 40 157 A1 a synchronizing ring is known which comprises a ring body with a sliding region, on which a film is applied by spray coating. The film is made of a brass alloy comprising copper, zinc and at least one element selected from the group consisting of aluminum, manganese, iron, nickel, silicon, cobalt, chromium, titanium, niobium, vanadium, zirconium and molybdenum , The film is applied by a spray coating. The brass alloy should have a structure consisting of a matrix and an intermetallic compound that is harder than the matrix. There is a risk that parts of the intermetallic compound are released and are transported away by the oil and thus increase the wear on the counter-cone. Next is a disadvantage that brass alloys are very sensitive to oil. Another disadvantage is that in brass alloys, the coefficient of friction is very temperature-dependent and they tend to eat. In addition, the brass alloys are quite expensive to buy, which is particularly important during spraying, since half of the material is sprayed and must therefore be recovered in a complex manner.

In this context is from the DE 44 45 898 A1 a friction pairing for a synchronizer known whose friction partners consist of a ferrous material with wear-resistant edge zone. The friction partners, ie, friction body and counter body are formed homogeneously and do not consist of a base body and an associated friction lining.

Also are from the DE 38 08 460 A1 and the DE 43 40 758 C2 wear-resistant chromium-iron alloys become known. However, iron-based sintered alloys whose chromium content is at most 7% are described in these prior publications.

Summary the invention

Of the The invention is therefore based on the object, a friction pairing develop during the the friction process, a low wear and the lower Material costs caused.

According to the invention this Problem according to the characterizing part of claim 1 solved by that the friction lining is a chromium-iron alloy containing 10-60% Cr, 0.3-0.5 % C, remainder contains Fe and a strength of 10-200 μm.

Of the decisive advantage of the alloy according to the invention lies in that these are very temperature resistant is, d. H. the friction effect is maintained up to temperatures of 700 ° C. The alloy has a low tendency to seize and works even at high wing loads perfect. It is further beneficial that this chromium-iron alloy while maintaining a favorable Coefficient of friction μ im Range from 0.06 to 0.2 compared to other alloys very much inexpensive is.

Appropriately, the friction lining is on the body applied by thermal spraying. The adhesive strength of the sprayed friction lining on the body is to be described as very good. Also, accurate spraying is possible because the alloy does not tend to form lumps during spraying. By depositing the friction lining as a thin-walled film installation space is saved. In addition, this chromium-iron alloy allows a targeted spraying in terms of the desired roughness of the friction lining.

Next Thermal spraying also involves other types of connection Friction lining and body possible. So can the chromium-iron alloy in the form of a film on the body welded or glued on. Also a positive attachment of the film at the base body is possible. Other variants include the sintering of the chromium-iron alloy and the attachment of chromium-iron powder on the body by means of adhesive components.

Further advantageous embodiments of the invention are in the dependent claims 2 to 11 described.

To Claim 2, the alloy of the invention in addition 3 to 25 molybdenum, 0.4 to 3.5% boron, 3 to 18% aluminum, 4 to 12% silicon, 0.5 contain up to 6% vanadium and 0.5 to 6% niobium. By the thermal Spraying leaves yourself the desired Strength adjust the friction lining. From claim 3 it is apparent that the friction body be subjected to a nitriding or a Nitrocarburierbehandlung should. This produces (mixed) nitrides or (mixed) carbonitrides, which are preferably enriched in the surface layer. Through this layer also called compound layer becomes the metallic character the surface changed again, so that the friction lining outer mechanical Attacks a greater resistance can afford. In this case, the friction coefficient is lowered, the adhesion to wear partner reduces and increases the abrasion resistance.

To a further feature of the invention according to claim 4 is provided, that the friction body a surface roughness before coating Ra of> 0.5 microns should. This can be done for example by shot peening. Under Rays is in expert To understand a manufacturing process in which blasting agents in blasting machines of different systems accelerated and impact on the to be processed surface to be brought. The shot peening is done especially with round or at least rounded abrasive grains. This can be different Plants are used, such. B. blast wheel blasting machines, in which the blasting medium in one or more centrifugal wheel devices by centrifugal forces the desired Speed is accelerated. But also pneumatically operated Pressure jet systems of different types are conceivable. When Blasting agents could For example, glass beads, steel balls or corundum balls used become. The aim of this shot blast treatment is a roughening and Activation of the surface of the basic body, which should lead to a better adhesion of aufzuspritzenden friction lining. For roughening the surface are in this context all known to the expert solutions conceivable, such. B. also a brush the surface or structuring by laser treatment.

Out Claim 5 shows that the friction body after coating a average roughness Rz should have from 20 to 100 microns.

In the claims 6 to 9, the counterpart acting as a second friction partner is described in more detail. Thereafter, this can be made of a steel alloy, a cast material, made of a copper alloy or a sintered material be. The steel alloy is a 16MnCr5 steel, 100Cr6, C45, 80Cr2 or C15. The counterbody can in the case of a casting material from a cast steel alloy of the GG20 brand. If it is made as a sintered material, so This may be an iron or bronze based sintered alloy.

In the last two claims 10 and 11 is the preferred application of the friction mating according to the invention described. According to claim 10 this is in a synchronizer for a change-speed gearbox be used, in order to achieve a synchronism with each other positive detachable drive means a synchronizer ring and a coupling ring directly or over a friction ring arranged between them at their respective conical friction surfaces a frictional connection received. According to claim 11, finally, the friction pairing be used in a multi-plate clutch, in which with a first Shaft connected surface ground outer fins in with a second Wave connected sinusoidal Inner fins comb-like intervene, the frictional engagement between the lamellae is made by their juxtaposition.

The Invention will be explained in more detail in the following embodiments.

Short description the drawings

It demonstrate:

1 a section shown Cross-section of a friction pairing in a synchronization mechanism for change-speed gearboxes,

2 a cross section through a multi-plate clutch,

3 an enlarged view of the slats in the decoupled state,

4 an enlarged view of the slats in the coupled state and

5 Representation of the friction coefficient as a function of the switching cycle.

Full Description of the drawings

After 1 is the synchronizing ring shown in section with 1 and the dome ring also shown in section 6 designated. The synchronizer ring 1 has the main body 2 on, on its inner conical lateral surface with the friction lining 3 is provided. The synchronizer ring 1 is radial with the driver toothing 4 provided over which it is connected via a sliding sleeve, not shown, with a shaft rotatably, but axially slidably connected. In the radial drive teeth 7 of the dome ring 6 engages a corresponding toothing of the sliding sleeve for the positive connection of shaft and coupling ring 6 , For the positive connection erforderli Chen synchronization between synchronizer ring 1 and dome ring 6 produces a cone clutch, ie the synchronizer ring 1 is with an inner cone and the dome ring 6 provided with an outer cone, the corresponding friction surfaces 5 and 8th own, with the friction surface 5 through the friction lining 3 is formed.

The synchronizer ring 1 is made in the embodiment of 80Cr2, ie it has a carbon content of 0.8% and a chromium content of 0.50%. It is made without cutting on a shaping unit. This process, for example, a drawing process, can be so precise that a grinding to set a certain height is unnecessary. After degreasing or cleaning of this soft synchronous blank this is applied in a suitable unit with a blasting abrasive of corundum, so that its surface has a roughness Ra> 0.5 microns. After blasting, the residual blasting agents used are removed before coating with the friction lining. The blasting to achieve the said roughness or roughness is required so that the friction lining 3 a good adhesion on the body 2 of the synchronizer ring 1 having. As an additional advantage of the blasting, it can be seen that the surface wall layer of the synchronizer ring 1 solidified and thus an increase in the fatigue strength is achieved. By blasting with corundum, silicon carbide or other abrasives, the surface is cleaned, roughened and activated. In order to avoid re-contamination or oxidation, the application of the friction lining should 3 that the friction surface 5 forms, done immediately after blasting. The friction lining 3 is a chromium-iron alloy on the inner cone of the synchronizer ring 1 applied in the following chemical composition:
20% chromium, 3% niobium, 3% vanadium, 1.5% carbon, 1.5% boron and the balance iron

The application of the friction lining 3 on the synchronizer ring 1 takes place by thermal spraying, ie a coating process in which a spray material in the form of wire or powder inside or outside a sprayer melted and at high speed on the surface or the conical surface of the synchronizing ring to be coated 1 is injected. The inner cone surface of the synchronizer ring to be coated 1 is not on or melted, ie the synchronizer ring 1 heats up only slightly during spraying, so that no thermal distortion can occur. In an advantageous manner, it has been found that, in particular, flame spraying and arc spraying are suitable for the present application. When flame spraying, the energy for melting the spray material is achieved by combustion of gases and arc spraying by electrical energy. The to the synchronizer ring 1 associated dome ring 6 is made of a copper alloy.

At the in 2 The arrangement shown are the two waves 9 and 10 connected by a switchable friction clutch in the form of a sine-plate clutch. In this carries the wave 10 outer disk 11 while the wave 9 with inner fins 12 connected is. The flat ground outer plates 11 grip like a comb into the sinusoidal corrugated inner fins 12 one. The in 4 shown engaged state is done by moving the shift sleeve 13 so that the angle lever 14 the axially movable slats 11 . 12 aneinanderpreßt. When disengaging the clutch according to 3 eliminates the pressure on the disk pack, so that inner disks 12 and outer plates 11 are separated from each other. In accordance with the invention, either the inner disc pack 12 or the outer disc pack 11 provided with a chrome-iron coating.

In 5 Finally, the course of the friction coefficient as a function of the switching cycle of the chromium-iron alloy according to the invention is shown. It can be seen that with increasing switching the coefficient of friction decreases only slightly. This drop is due to the running-in behavior of the two friction surfaces 3 . 5 due. By optimizing the composition can with the Coating friction values between 0.12 - 0.1 can be achieved at up to 150 000 switching cycles regardless of the type of gear oil used.

1

synchronizer ring

2

body

3

friction lining

4

driver toothing

5

friction surface

6

coupling ring

7

driver toothing

8th

friction surface

9

wave

10

wave

11

outer plate

12

inner plate

13

shift sleeve

14

bell crank

Claims (11)

Friction pair with at least one friction body and a counter body, wherein at least one friction body from a base body ( 2 ) and a friction lining ( 3 ), which is connected to the main body ( 2 ), characterized in that the friction lining ( 3 ) is a chromium-iron alloy containing 10 - 60% Cr, 0.3 - 0.5% C, remainder Fe and having a thickness of 10 - 200 μm. Friction pairing according to claim 1, characterized in that that the chromium-iron alloy additionally contains 3 - 25% Mo, 0.4-3.5% B, 3-18% Al, 4 - 12% Si, 0.5-6 % V and 0.5 - 6 Contains% Nb. Friction pairing according to claim 1, characterized in that that the friction body a nitrating or a Nitrokarburierbehandlung is subjected. Friction pairing according to claim 1, characterized in that the basic body ( 2 ) has a surface roughness Ra> 0.5 μm before coating. Friction pairing according to claim 1, characterized in that that the friction body after coating has a mean roughness Rz of 20 - 100 μ. Friction pairing according to claim 1, characterized in that that the opposing body from a steel alloy, from a cast material, from a copper alloy or made of a sintered material. Friction pairing according to claim 6, characterized that the steel alloy is a 16MnCr5, 100Cr6, C45 steel, 80Cr2 or C15 is. Friction pairing according to claim 6, characterized that as a casting material a cast steel alloy the GG20 brand is used. Friction pairing according to claim 6, characterized that the sintered material is an iron-based sintered alloy or is based on bronze. Friction pairing according to claim 1, characterized in that it is used in a synchronizer for a change-speed gearbox, in which to achieve a synchronization with each other form-fit detachable drive means a synchronizer ring ( 1 ) and a coupling ring ( 6 ) directly or via a friction ring arranged between them on their respective conical friction surfaces ( 5 . 8th ) make a frictional connection. Friction pair according to claim 1, characterized in that it is used in a multi-plate clutch, in which with a first shaft ( 10 ) connected surface ground outer plates ( 11 ) in with a second wave ( 9 ) connected sinusoidal inner plates ( 12 ) engage in a comb-like manner, the frictional engagement between the slats ( 11 . 12 ) is produced by their juxtaposition.