DE102020122935A1 - plain bearing element - Google Patents

Abstract

The invention relates to a plain bearing element (2) in the form of a plain bearing shell (4) or a thrust washer (6), each made of a plain bearing composite material with a metallic supporting layer (16), in particular made of steel, with a bearing metal layer (18) applied to the supporting layer (16). and having a polymer-based sliding layer (22) applied to the bearing metal layer (18); According to the invention, it is proposed that the bearing metal layer (18) is a tin base layer (20) galvanically deposited on the supporting layer (16) and has a thickness of 8.0 - 50.0 µm and that the sliding layer (22) is polymer-based a bonded lacquer layer (24) with a thickness of 8.0 - 15.0 µm.

Description

The invention relates to a plain bearing element in the form of a plain bearing shell, in particular a connecting rod bearing shell, or a thrust washer, in particular for a crankshaft, each made of a plain bearing composite material with a metallic supporting layer, in particular made of steel, with a bearing metal layer applied to the supporting layer and with a sliding layer applied to the bearing metal layer polymer based.

In such known plain bearing elements for engine or engine-related applications in particular as a connecting rod bearing shell or thrust washer, a usually at least 150 μm, typically 200-500 μm thick bearing metal layer based on aluminum, bronze, brass or white metal is cast or plated onto the steel supporting layer. A bonded coating layer that is in direct contact with the sliding partner can also be applied as a sputter layer, as a galvanic layer or as a polymer layer.

WO 2020/118327 A1 discloses a sleeve-shaped welded sliding bearing element with a sliding coating on its radially outer side. A three-layer plain bearing element consisting of a support layer, a bearing metal layer and a polymer bonded coating layer is mentioned, it also being possible for fewer or more than three layers to be provided. The polymer of the sliding layer is preferably polyamideimide.

The present invention is based on the object of creating a plain bearing element of the type mentioned at the outset that can be produced more cost-effectively than previously known plain bearing elements and yet does not entail any disadvantages with regard to wear resistance and the coefficient of friction.

In the case of a plain bearing element of the type mentioned, this object is achieved according to the invention in that the bearing metal layer is a tin-based layer which is electroplated onto the supporting layer and has a thickness of 8.0-50.0 μm and that the polymer-based sliding layer has a bonded coating layer with a thickness of 8.0 - 15.0 µm.

With the present invention, it was recognized that it is possible to dispense with a thick cast or plated-on bearing metal layer and instead to form the bearing metal layer as a thin galvanically deposited tin base layer. On the one hand, this thin tin base layer forms a resilient base for the bonded coating layer that is preferably applied directly to it, although tin is not recommended for use as a load-bearing layer. However, thin layers generally wear better than thick layers. By reducing the thickness of the bearing metal layer, a galvanic tin base layer can withstand the loads that occur here. In addition to its function as a supporting base for the anti-friction layer, the tin-base layer can also ensure embedding for foreign particles which have penetrated or penetrated the polymer anti-friction layer, particularly during running-in of the plain bearing element.

A plain bearing element according to the invention and a plain bearing composite material on which it is based can be produced more cost-effectively due to the reduced complexity of the production process by using two wet processes and a significant reduction in the material, without any losses in performance being associated with this.

The tin base layer can comprise tin or a tin alloy, in particular a tin-copper alloy, in particular an SnCu6 alloy.

It has proven to be advantageous if the tin base layer has a thickness of at least 9.0 µm, in particular at least 10.0 µm, in particular at least 11.0 µm, in particular at least 12.0 µm, in particular at least 13 .0 μm, in particular at least 14.0 μm, in particular at least 15.0 μm, in particular at most 45.0 μm, in particular at most 40.0 μm, in particular at most 35.0 μm. The smaller the thickness of the tin base layer, the more stable and resilient the bearing metal layer it forms, and the production costs are also reduced. The greater the thickness of the tin base layer, the more potential it creates for embedding foreign particles. Optimum results are achieved with layer thicknesses between 10.0 and 40.0 µm, in particular between 15.0 and 35.0 µm.

It is also conceivable and can prove to be advantageous if the tin base layer has embedded hard particles, in particular made of ... and/or solid lubricant particles, in particular made of MoS ₂ , graphite, PTFE. Such particles can be introduced into the galvanic bath from which the tin base layer is deposited, so that when the tin base layer is grown they are also included therein and become part of the bearing metal layer.

In conjunction with the claimed tin base layer as a bearing metal layer, it has proven to be advantageous if the anti-friction coating layer has a thickness of at least 9.0 μm and in particular at most 14.0 μm, in particular at most at least 13.0 µm. With these layer thicknesses, a very good load-bearing capacity is still achieved, and the plain bearing layer itself also offers a certain potential for embedding small foreign particles.

The polymer basis of the bonded coating layer is preferably polyamideimide (PAI).

In conventional plain bearing elements, a final shape of the geometry of the plain bearing element, in particular a so-called ovalization of a half-shell-shaped plain bearing element, is achieved on a previously produced composite of metallic support layer and relatively thick bearing metal layer by machining the bearing metal layer. In this way, a bearing metal layer is obtained with a wall thickness that varies over the circumference of the plain bearing element, while the wall thickness of the metal support layer remains the same. This can mean undesirable variations in the load capacity and other tribological properties of the plain bearing element in the circumferential direction. - In a further development of the present invention, it is further proposed that the metallic support layer is formed starting from a metallic flat material section of uniform thickness, by bringing the flat material section into a shell shape and then machining it on a radially inner side of the shell shape and machining it to a final shape varying wall thickness was brought and that the tin base layer is electroplated directly onto the machined radially inner side of the flat material section and the bonded coating layer is applied to it. In such a case, an inner contour of the plain bearing element that is to be deliberately produced, i.e. a deviation from the ideal cylindrical geometry, in particular in the form of a so-called ovalization, is obtained by machining the metallic support layer and not the bearing metal layer, so that the bearing metal layer is in the form of the galvanically applied tin base -layer with uniform wall thickness can be applied to the previously machined metallic backing layer. The machining of the metallic support layer can consequently also be readily recognized on the finished product by means of a varying wall thickness of this support layer.

Protection is also claimed for a method having the features of claim 8 and for a method having the features of claim 9.

• 1 eine Seitenansicht eines erfindungsgemäßen Gleitlagerelements in Form einer Gleitlagerschale;
• 2 eine schematische nicht maßstabsgetreue Querschnittsdarstellung mit Schnittebene II-II des Gleitlagerelements nach 1; und
• 3 eine Draufsicht auf ein erfindungsgemäßes Gleitlagerelement in Form einer Anlaufscheibe.

Further features, details and advantages of the invention result from the appended patent claims and from the drawing and the following description of a preferred embodiment of the plain bearing element according to the invention. In the drawing shows:

• 1 a side view of a plain bearing element according to the invention in the form of a plain bearing shell;
• 2 a schematic cross-sectional representation, not true to scale, with section plane II-II of the plain bearing element 1 ; and
• 3 a plan view of a plain bearing element according to the invention in the form of a thrust washer.

The figures show a plain bearing element 2 in the form of a plain bearing shell 4 ( 1 and 2 ) and a thrust washer 6 ( 3 ). The plain bearing shell 4 has an essentially ideal cylindrical shape on its radially outer side 8 . The plain bearing shell 4 is a connecting rod bearing shell which, corresponding to its outer circumference, can be accommodated in an essentially ideally internal cylindrical receptacle in the large connecting rod eye of an engine connecting rod. On its radially inner side 10, the plain bearing shell 4 has a final shape that deviates slightly from the ideal cylindrical shape. The radially inner side 10 is in particular slightly ovalized, which is also not to be understood in a strictly geometrical sense, but rather means a varying course that deviates slightly from the cylindrical shape in the circumferential direction 12 . It is also conceivable that the radially inner side 10 is contoured in the axial direction 14, ie is designed to deviate from the ideal cylindrical shape.

Below is the layer structure of the plain bearing element 2 based on the schematic cross-sectional view of 2 explained. The plain bearing element 2 comprises a metallic support layer 16, in particular and preferably made of steel, a bearing metal layer 18 in the form of an electrolytically deposited tin base layer 20 that is preferably applied directly thereto and a sliding layer that is preferably applied directly to the tin base layer 20, in particular sprayed on 22 based on polymers in the form of a bonded coating layer 24, preferably based on PAI or consisting of PAI.

For the production of the plain bearing element 2 according to 1 and 2 the support layer 16 is formed starting from a metallic flat material section made of steel, which was in particular cut to length from an endlessly supplied strip of flat material as a circuit board section, by placing the flat material section on the in 1 indicated end shape is brought, which happens in a bending-rolling process. Then the half-shell-shaped support layer 16 is machined on its inside and the final geometric shape of the sliding bearing element 2 is already defined. Then, the half-shell-shaped element consisting of the support layer 16 is placed in an electroplating apparatus introduced, and the bearing metal layer 18 of the tin base layer 20 is deposited there with a substantially uniform thickness. The intermediate product obtained in this way, consisting of support layer 16 and bearing metal layer 18, is then coated with the anti-friction coating layer 24, in particular by spraying on anti-friction coating, again with a constant, uniform layer thickness.

Finally shows 3 a plan view of a plain bearing element 2 according to the invention in the form of a thrust washer 6, the visible side being formed by the bonded coating layer 24.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2020/118327 A1 [0003]

Claims (9)

Plain bearing element (2) in the form of a plain bearing shell (4) or a thrust washer (6), each made of a plain bearing composite material with a metallic supporting layer (16), in particular made of steel, with a bearing metal layer (18) applied to the supporting layer (16) and with a polymer-based sliding layer (22) applied to the bearing metal layer (18), characterized in that the bearing metal layer (18) is a tin-base layer (20) which is electroplated onto the supporting layer (16) and has a thickness of 8.0 - 50, 0 µm and that the polymer-based sliding layer (22) is a sliding lacquer layer (24) with a thickness of 8.0-15.0 µm. plain bearing element claim 1 , characterized in that the tin base layer (20) comprises tin or a tin alloy, in particular a tin-copper alloy, in particular a SnCu6 alloy. Plain bearing element (2) after claim 1 or 2 , characterized in that the tin base layer (20) has a thickness of at least 9.0 microns, in particular at least 10.0 microns, in particular at least 11.0 microns, in particular at least 12.0 microns, in particular at least 13.0 μm, in particular at least 14.0 μm, in particular at least 15.0 μm, in particular at most 45.0 μm, in particular at most 40.0 μm, in particular at most 35.0 μm. Plain bearing element (2) after claim 1 , 2 or 3 , characterized in that the tin base layer (20) has embedded hard particles, in particular from the group of nitrides, carbides or oxides, in particular cubic boron nitride BN, silicon carbide SiC, titanium dioxide TiO2, aluminum oxide Al2O3, iron oxide Fe2O3, and/or solid lubricant particles, in particular made of MoS ₂ , WS2, graphite, PTFE. Plain bearing element (2) according to one or more of the preceding claims, characterized in that the anti-friction coating (24) has a thickness of at least 9.0 µm and in particular at most 14.0 µm, in particular at most 13.0 µm. Sliding bearing element (2) according to one or more of the preceding claims, characterized in that the polymer base of the bonded coating layer (24) is polyamideimide (PAI). Plain bearing element (2) according to one or more of the preceding claims, characterized in that the metallic support layer (16) is formed starting from a metallic flat material section of uniform thickness by bringing the flat material section into a bowl shape and then on a radially inner side of the bowl shape was machined and brought to a final shape with varying wall thickness and that the tin-base layer was electro-deposited directly on the machined radially inner side of the flat material section and the anti-friction coating layer is applied thereto. Method for producing a plain bearing element (2) according to one or more of the preceding claims, characterized in that the metallic supporting layer (16) is formed starting from a metallic flat material section of uniform thickness, by the flat material section being brought to its final shape with regard to its shape and thickness and that the tin base layer (20) is electrodeposited directly onto a side of the flat material section facing a sliding partner and that the anti-friction lacquer layer (24) is applied, in particular sprayed on. procedure after claim 8 , characterized in that the metal support layer (16) is formed starting from a metal sheet section of uniform thickness by bringing the sheet section to a cup shape, and in that the sheet section is subsequently machined on a radially inner side of the cup shape and to a final shape of varying wall thickness and that the tin base layer (20) is electro-deposited directly on the machined radially inner side of the flat material section and that the anti-friction lacquer layer (24) is applied thereto, and that a plain bearing element (2 ) of varying wall thickness, but without machining the bearing metal layer.

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