DE2840425C3 - Process for the production of workpieces subject to friction, such as slide bearings, with an adaptation layer suitable for exposure to relatively high surface pressure and / or friction or wear and / or high temperature - Google Patents

Description

The invention relates to a method for producing workpieces subject to friction, like plain bearings, with for loads with relatively high surface pressure and / or friction or wear and / or high temperature suitable adaptation layer.

The basic meaning of the invention is given below using the example of plain bearing elements shown.

Every time a hydrodynamically lubricated bearing is started or switched off, the Crossed zone of mixed friction. This leads to direct partial contact between the plain bearing material and shaft material. This creates a more or less depending on the load heavy wear and tear on the mating partners. In the case of plain bearings, an adjustment process is usually necessary in order to In the case of new, virgin bearing pairings, the micro-geometries between the shaft and the bearing are aligned to bring about, i.e. the roughness peaks or the to smooth geometric inaccuracies through programmed wear, and thus the contact area of the

ίο sliding element and thus the permissible mechanical Increase load limit. Here, the time required for this process has so far mainly been from the Properties of the tribological system plain bearing material / shaft material / lubricant dependent.

In GB-PS 14 09 477 a rotary piston is described, which with a surface layer of FeO is occupied by plasma spraying. This layer produced by plasma spraying should be up to 5 mm thick be applied. This layer, applied by thermal spraying, has a relatively smaller one Hardness than that of the rotary lobe housing, which thus leads to a reduction in wear and tear and the tendency to seize However, such sliding layers for plain bearings are not applicable to the partial pressure and during operation Have temperature peaks.

Through the use of galvanic coatings for heavy-duty, ready-to-install bearing shells for internal combustion engines, so-called three-substance bearings are preventive adjustment processes, e.g. B. for car engines practically omitted, while with diesel engines in the range from 370 to 1580 KW the adjustment time from 20 to; 30 to 2 to 5 hours could be reduced. In the case of three-substance bearings, a basic layer of the basic Plain bearing material, consisting, for. B. made of copper or aluminum alloy materials, a ductile galvanic Coating with a layer thickness of 0.015 to 0.040mm is usually custom-made by electroplating, i.e. without repeated subsequent mechanical processing applied

The adaptability of the relatively soft, ductile electroplated layer favors the adaptation process and increases both the resistance of the sliding bearing to welding to the shaft as well the wettability with lubricants. The galvanic coatings consist of either lead-indium or lead-tin or made of lead-tin-copper. In the case of the latter, alloys with increased copper contents have recently been added Up to 10% mass fraction known The demands made by the engine manufacturers for increased Have resilience and fatigue resistance as well as wear resistance and corrosion resistance led to these newer galvanic layers, which, however, due to their higher hardness, the conditions for the effectiveness of the adjustment process no longer fully satisfactory. That tried to get closer to the lubricating oil by adding EP additives, with the removal of Roughness peaks are caused by a linked chemical-mechanical process. By partial Touching during the adjustment process creates pressure peaks and temperature peaks, so to speak, which lead to a chemical reaction of the aggressive active ingredients of the additives with the materials fen the bearing with the formation of z. B. metal sulfides, chlorides, phosphates lead to increased im Area of mixed friction of the bearing point the processes of mechanical and chemical removal of the

Boundaries run side by side. It has been shown that after a long period of time under stress, especially in the field of mixed friction, bearing material and shaft material through non-metallic Isolation layers are separated, which leads to the welding formation of adhesion bridges and thus material fatigue due to high shear forces is avoided. It was observed that the Reaction transformation of the sliding material surfaces, in particular the electroplated layer consisting of Pb — Sn-Cu, during the adjustment phase - depending on the type and size of the roughness and the operating conditions of the engines (long or short distance driving and corresponding temperatures) - very Unevenly distributed over the bearing metal surface and also uncontrolled over time expires, which can naturally give rise to operational disruptions. Due to operational use Such additives or inhibitors in the lubricant are only formed in loose layers that are in the Run-in and run-out phases of the company are rubbed through again and again, so that it actually never comes to Formation of a homogeneous and cohesive non-metallic sliding layer can occur. Much more the layers created in the lubricant by such additives and inhibitors are only a stopgap measure and provide some protection during operation.

The object of the invention is therefore to develop a method with the improved matching layers for z. B. elements subject to friction, in particular also conventional multilayer guide elements, created outside of operational use will.

The object of the invention is achieved in that the workpieces in a lubricant bath with at least one such anti-wear and anti-corrosion High-pressure additives, as they are per se as in operational use under the influence of increased Pressure and temperature partially effective additives or inhibitors in natural and synthetic Lubricants or emulsions to reduce friction, wear, temperature or Corrosion are known, through chemical conversion of the workpiece surface preventively with a closed, continuous, between 0.0Cl mm and 0.005 mm, preferably 0.002 mm thick reaction layer based on dry friction and Metal salts that prevent wear and tear of metal surfaces can be used as an adaptation layer.

Surprisingly, it has been found that the adaptation layer according to the invention, produced in the lubricant bath, has significantly better properties than those in the operational use of such additives or inhibitors in the lubricant can be achieved. Tests have shown that according to the invention The built-up adaptation layer on slide bearings can achieve up to 50% higher compressive strength than this is possible with the operational use of the same additives or inhibitors in the lubricant. Through this Increasing the pressure resistance of z. B. plain bearings, it is possible the overall length of internal combustion engines, due to the slim design of the plain bearings with a high load-bearing capacity at the same time, essential to diminish.

High pressure kits are added or dissolved to lubricants, only at high pressure and high Substances that take effect at temperature (so-called additives: phosphorus, chlorine, sulfur or others Compounds) to paraffinic, naphthenic or mixed base oils and result in so-called alloyed lubricants. They form upon reaction with the metals a pressure-resistant, non-metallic surface layer that separates the sliding surfaces well of higher shear strength in the form of metal chlorides, metal phosphates, metal sulfides, a chemical boundary layer in the form of metal salts, the dry friction

ίο and welding of metal surfaces is therefore prevented also called corrosive or solid lubrication. On the type of soluble compound and the temperature stress the wear-reducing effect depends. Therefore, alloyed lubricants are only from a certain load and temperature to use. Furthermore, the application of crystalline Phosphate coatings for cold forming of steel as well as zinc, zinc alloys, aluminum and aluminum alloys when drawing wires, tubes and profiles, deep drawing, cold forming, extrusion for the purpose of elimination the metallic contact between workpiece and tool as a separating agent and as a good lubricant carrier and at the same time as a lubricant and to improve the surface and its corrosion resistance known Bonder layers where the phosphate layer with the Basic metal; is chemically fused, in contrast to the usual lubricant carrier. The amount of work required to produce phosphate or bond layers is but considerable and therefore expensive.

It has long been known that e.g. B. EP additives in lubricants at high pressure and at high Temperature take effect. Yet it was not at hand to the average professional lying, EP additives only under the action of a predetermined temperature and during a certain To bring time to advantage in a targeted manner for the purpose of producing improved, preventive Adaptation layers to reduce wear and temperature, especially in the area of Mixed friction, for elements subject to friction, e.g. B. for highly stressed multilayer plain bearings.

By this method according to the invention for the production of improved, preventive adjustment layers is z. B. created a plain bearing element that the conventional and as optimal technical Solution regarded three-substance bearings, especially with regard to reducing wear and tear Temperature as well as an increase in fatigue strength

so as well as corrosion resistance is far superior.

Systematic row underruns on plain bearings have, among other things, shown that with inventive reaction treatment of conventional three-material plain bearings in liquid enriched with EP additives Lubricants, the durability and corrosion resistance are surprisingly positive be influenced.

Advantageously, the conversion can be carried out in a liquid lubricant bath at a temperature between room temperature and 70 ^° C. with 1% to 5% mass fraction of thiophosphoric acid-OOO-triphenyl ester in a time between 0.1 and 10 hours, in particular 2 hours. In a particularly advantageous manner, the conversion

b5 are carried out at 150 ⁰ C with 2% mass fraction of thiophosphoric acid Ο, Ο, Ο-triphenyl ester. The adaptation layer can also be converted from a 0.001 to 0.005 mm thick PbSn or Sn or PbCu

or PbSnCu layer can be produced.

Although the following example focuses primarily on a selected conventional, multilayer Relates sliding bearing element, it goes without saying that other embodiments for sliding bearing elements with regard to the production of wear, temperature, and grain-inhibiting layers, as well for other metallic elements that are to be subjected to high friction loads than the plain bearings described in accordance with simple and inexpensive treatment method within the scope of the invention are possible, such. B. Support journals, pistons, cylinder walls, guides, roller bodies, tool surfaces, tooth flanks of gear wheels, valve guides, piston rings, Roller and inverted tooth chains, etc.

Three-substance bearing with a conventional layer structure consist of:

Steel support body, cast 0.3 mm thick copper-lead alloy - CuPb 22 Sn - as the base layer, galvanically applied 1.5 μm thick nickel dam as a barrier layer with an approximately 22 μm thick ternary sliding and adaptation layer as PbSnIOCu, provided on all sides with a 2 μπι thick lead-tin top layer, treated for example over 2 hours at a determined temperature of 150 ⁰ C in a HD oil 20 W / 20, in which 2% by mass of thiophosphoric acid Ο, Ο, Ο-triphenyl ester (TPPT) are dissolved . A closed, deep black reaction coating forms on the surface.

The plain bearings treated according to the invention were subjected to a test on a plain bearing test stand. For these tests, each of the plain bearing halves to be tested are mounted in the lower part of the bearing receptacle. In the upper part of the bearing mount is each built a conventional plain bearing shell without inventive aftertreatment. To set the test conditions (speed, lubricant temperature, specific plain bearing load) only the upper untreated plain bearing half is statically loaded due to a larger bearing clearance in the one to be tested In addition, it is ensured that the journal does not get in contact with the test shell when the bearing half is started mechanical contact comes after setting the test conditions by changing the load direction The sliding bearing half to be tested is statically loaded by means of a continuously adjustable hydraulic cylinder via a lever arm on the bearing receptacle. The lever arm is mounted on tips and acts as a result at the same time as a friction balance. The coefficient of friction is determined using a pressure cell:

Test data

lubricant Lubricant inlet

temperature

Lubricant inlet pressure Stock taking Tenon material Tenon roughness Journal diameter Plain bearing width rotational speed

SAE 30 (HD)

120 ⁰ C

5 bar

0 58.6 mm

Ck 45 HRC 55

Ra 0.14-0.18 μm

5433 mm

22 mm

2000 min .- '= 5.75 m / s

Thiophosphoric acid O, O, O-triphenyl ester dissolves in Mineral oils and synthetic oils. The maximal Solubility in paraffinic oils is about 5%, while it is for naphthenic base oils and ester oils is more than 10%

Thiophosphoric acid O.O.O-triphenyl ester is used as

EP additive in natural and synthetic lubricants, hydraulic oils and cutting fluids used.

The use of triaryl phosphates, e.g. B. tritolyl phosphate (TTP), as EP additives is also known Effectiveness of these agents leads one to the formation of metal phosphates on the metallic surface back, but they have limited XP since heavy loads are not absorbed

iu can. Products with better load-bearing properties such as B. zinc dialkyldithiophosphate (ZDTP), Sulphurized oils, fats, chlorinated paraffins, etc. are often preferred but are more corrosive and have a lower temperature resistance ZDTP additives are ash-forming, which is a significant disadvantage Thiophosphoric acid O.O.O-triphenyl ester is an ashless EP additive, which in its properties ZDTP and also has a corrosion-inhibiting effect with certain additives (GB-PS 10 18 307).

μ Although the TPPT-EP additive is highlighted as being particularly suitable in the example shown, it is It is entirely possible to use other sulfur- and / or phosphorus-containing products to create improved adaptation layers. Likewise, oxide layers can be used successfully for parts with a specific purpose, such as systematic studies have shown.

An embodiment of the invention is shown on the basis of the figures:

F i g. 1 is a perspective view of a plain bearing half according to the invention;

F i g. 2 A detail AB in a preferred embodiment of the sliding bearing half according to FIG. 1, enlarged and in section;

3 shows a schematic representation of the wall thickness reduction for untreated -a- and -b- plain bearing halves treated according to the invention as a function of the static load; Fig. 4 Diagram of the temperature characteristics for

-ίο untreated -a- and treated according to the invention -b- plain bearings depending on the static

Load, each measured on the back of the bearing after 15 Minutes of operating time and Fig. 5 Comparison of the friction characteristics

also for -a- and -b- depending on the static load measured firstly - 1 - in virginal condition immediately after switching on the load and secondly -2- after 15 minutes Adjustment time

So in the example of FIG. 1 and 2 is a base layer 4 of a steel support body 5 Copper-lead-tin alloy CuPb22Sn with a layer thickness of about 0.2 πϊϊΰ to 0.7 now applied On this base layer 4 is an extremely thin layer 3 (Thickness 0.001 to 0.002 mm) made of nickel the at conventional three-substance bearings serves as a diffusion barrier. Above the diffusion barrier layer 3 is z. Legs about 0.022 mm thick ternary sliding and adaptation layer 2 made of PbSnIOCuZ on the sliding layer 2 and also on the steel support body 5 is initially a 0.001 mm to 0.005 mm, preferably 0.002 mm thick

Lead-tin top layer 1, which is subsequently the

inventive reaction treatment is subjected.

The F i g. 3, 4 and 5 give the opposite

Characteristic curves for wall thickness changes as well as temperature and friction behavior of the untreated —a— and treated - b - plain bearing shells with variable bearing pressures under static load.

The diagrams clearly show the superiority of the - b - plain bearings treated according to the invention in terms of maximum load capacity under the test conditions mentioned above. The untreated - a - plain bearings fail at a bearing pressure of 42 N / mm ² in contrast to the plain bearings treated according to the invention, which only expose ^{at a bearing pressure of about 80 N / mm 2.}

Subsequent investigations with practical installation conditions under difficult test conditions, e.g. under changing loads, speeds, lubricant temperatures, lubricant quantities or Lubricant pressure and the like clearly show the advantage of the so-called Dreis'.offiager treated according to the invention over the standard untreated ones. Execution. Subsequent tests in high-speed racing engines with turbocharging and fuel injection took place - in contrast to untreated three-fuel bearings - without any difficulty.

Subsequent expansion unmistakably showed the advantage of the preventive inventive reaction treatment of the adaptation layer in relation to Surface quality, dimensional accuracy, friction and resilience in comparison with a conventional layer structure. Not just plain bearings right in Solid and / or layered design, also other metallic elements, which have high friction or Subject to wear, can be subjected to a similar simple, inexpensive, prophylactic reaction treatment of the surface layer, so that a wear-resistant or high-pressure-resistant and low-friction layer with dry lubrication properties is formed. With relatively small parts the reaction treatment is carried out in hundreds or thousands in one pass.

Instead of the above in connection with FIG. 1 and 2 explained structure of sliding bearing elements come sliding bearing elements with a different structure of the sliding layer for equipping with an adaptation layer according to the invention are also considered. For example, the sliding layer of a sliding bearing element can be made from consist of a suspension alloy that tends to separate, for example thermokinetically or also applied by application and mechanically compacted together with the carrier layer. This suspen-

Sion alloy can preferably be an aluminum-lead suspension. On the surface of a Such a sliding layer and into the surface can be the adaptation layer in the manner according to the invention be educated.

Another possible application of the adaptation layer according to the invention can also be found in Plain bearing elements whose sliding layer is formed by a white metal alloy, which is called a ternary Alloy 10% to 20% tin, 6 to 10% copper, the rest

r> lead, especially 16% tin, 8% copper, the remainder lead contains, whereby the tin should always represent 6 to 8% greater mass constituent than the copper. Also in such a sliding layer or a thin running-in layer placed over it can be the inventive

.'Ii adaptation layer are formed.

Another possibility of using the adaptation layer according to the invention is for hard, given thin layers, for example in such bearing elements with a thin layer of a hard one

. "> Tin-containing alloy covered with a layer of is underlaid with softer metallic material. In such a case, the layer can be made of a nickel-tin alloy with a tin content between about 30 and 90 Wt .-% and a maximum thickness of about

in 0.01 mm, preferably about 0.005 to 0.01 mm and covered with a maximum 0.05 mm, preferably 0.005 to 0.015 mm thick sliding layer made of bearing material with a Brinell hardness between about 4 and 30 kp / mm ² . In this case, too, can

r> above and in the layer and sliding layer the adaptation layer according to the invention be formed.

In addition to these examples, the adaptation layer according to the invention and its method of manufacture are also on practically all known layers of sliding and

ad bearing elements conceivable.

For this purpose 4 sheets of drawings

Claims (7)

Patent claims: 1. Process for the production of workpieces subject to friction, such as plain bearings, with for Load with relatively high surface pressure and / or friction or wear and / or or high temperature suitable adaptation layer, characterized in that the workpieces in a lubricant bath with at least one such anti-wear and anti-corrosion agent High-pressure additives, as they are per se as in operational use under the influence of increased Pressure and temperature partially effective additives or inhibitors in natural as well as synthetic lubricants or emulsions to reduce friction, wear, Temperature or corrosion are known through chemical conversion of the workpiece surface preventively with a closed, continuous, between 0.001 mm and 0.005 mm thick Reaction layer based on dry friction and preventing wear and tear of metal surfaces Metal salts are used as an adaptation layer. 2. The method according to claim 1, characterized in that the conversion in a liquid lubricant bath at a temperature between room temperature and 17O ⁰ C with 1% to 5% mass fraction of thiophosphoric acid-OAO-triphenyl ester is carried out in a time between 0.1 and 10 hours . 3. The method according to claim 2, characterized in that the conversion is carried out at 15O ⁰ C. 4. The method according to claim 2 or 3, characterized in that the conversion with 2% Mass fraction of thiophosphoric acid O.O.O-triphenyl ester is carried out. 5. The method according to any one of claims 2 to 4, characterized in that the conversion into carried out over a period of 2 hours. 6. The method according to any one of claims 1 to 5, characterized in that the adaptation layer is formed to a thickness of 0.002 mm. 7. The method according to any one of claims 1 to 5, characterized in that the adaptation layer by conversion from a 0.001 to 0.005 mm thick PbSn or Sn or PbCu or PbSnCu layer will be produced.