AT519124B1 - Multilayer plain bearing element - Google Patents

Abstract

The invention relates to a multilayer sliding bearing element comprising a supporting layer and a sliding layer, wherein the sliding layer consists of a white metal comprising the elements tin, zinc and copper, wherein the proportion of copper between 2 wt .-% and 8 wt .-% and the proportion of zinc between 35 and 50% by weight, preferably between 39 and 47% by weight, and the remainder forms tin. Preferably, at least 50% of the zinc content has a maximum particle size of 250 μm. The white metal is preferably a casting alloy, in particular a centrifugal casting alloy.

Description

Description: The invention relates to a multilayer sliding bearing element comprising a supporting layer and a sliding layer, the sliding layer consisting of a white metal comprising the elements tin, zinc and copper, the proportion of zinc being between 35% by weight and 50% by weight ,

Due to the increasing loads in the engine and thus on the camp a higher-strength sliding layer is desired by the market which, however, has no noticeably worse eating properties or at least no spontaneous failure as the commonly used AISn40 shows. To solve this problem a variety of solutions, especially different alloys, are known from the slide bearing manufacturer.

The use of white metals for a sliding layer of a multilayer plain bearing is known from the prior art. The current alloys are characterized by the use of solid solution hardening (addition of Sb, Bi, Cd) and hardening by primary precipitation (addition of Cu, Ni, Co). The risk of primary excretions is the segregation difficult to control in centrifugal casting due to centrifugal forces and the reduction in ductility due to the increased brittle phase fraction. Hardening by compression and fine-grain hardening (addition of Te, As) are not or only briefly effective due to the relatively high temperatures for white metals. In addition, the cost of the alloys is largely caused by the high tin content.

JP H10-330871 A describes a multilayer sliding bearing element with a base material on which a bearing metal layer is applied. On the bearing metal layer is formed a coating layer having a composition of Sn, optionally In, and substantially Zn with unavoidable impurities. This coating layer further contains at least one element selected from the group consisting of Sb, Cu, Ag and Au. It is thus a sliding element, which is free at least in the sliding surface of Pb and has a sliding characteristic which is equal to that of a sliding element with lead created.

From US 1,915,212 A, an alloy is known which contains 55% Sn, 38% Zn, 1% Cu, 5.5% Al and 0.1% of an amalgam. The alloy can i.a. be used for a sliding bearing.

JP 2003-322153 A describes a metal-impregnated carbon bearing material having a sliding property approximately equal to a lead-impregnated carbon bearing material while being lead-free. For this purpose, a carbon base material is used, which contains a solid lubricant and is impregnated with an alloy consisting of 20 to 29 wt.% Zn, 2-8 wt.% Cu and Sn as the remainder. In a comparative example, an impregnation consisting of 63% by weight of Sn, 32% by weight of Zn and 5% by weight of Cu is used.

The object of the invention is to provide a multilayer plain bearing with a sliding layer, which has improved strength, of a white metal, which is inexpensive to manufacture.

The object of the invention is achieved in the aforementioned multilayer sliding bearing characterized in that the proportion of copper between 2 wt .-% and 8 wt .-% is and forms the remainder tin.

The advantage here is that the relatively high cost of the multi-layer plain bearing caused by tin can be significantly reduced by the high proportion of zinc, since the price of zinc is about 1/10 of that of tin. Since zinc and tin are obtained from the same manufacturing process, it is unlikely that this ratio will change. The overlay with the specified composition also has a higher strength than currently used in multi-layer plain bearings white metals, but the loss of ductility of the alloy is surprisingly relatively low. Despite the high proportion of zinc, the good milling properties of the tin are retained. The sliding layer also has a higher fatigue strength. This is in the sense of the damage progress, so that less damage occurs with the same load and time and / or a higher load at the same time leads to the same damage advantage.

Characterized in that the proportion of copper is between 2 wt .-% and 8 wt .-%, an improvement in the strength of the sliding layer can be achieved because copper forms mixed crystals and primary precipitated hard phases with zinc.

A further improvement of these properties of the sliding layer can be achieved if the proportion of zinc between 39 wt .-% and 47 wt .-% is.

According to a further embodiment of the multi-layer plain bearing, a proportion of at least 50% of the total zinc content can be present with a maximum particle size of 250 pm. By means of this fine grain of the white metal alloy, a further improvement in the fatigue strength of the sliding layer can be achieved.

Preferably, the white metal is a casting alloy, in particular a centrifugal casting alloy. Casting methods are relatively fast compared to other methods for producing sliding bearing layers feasible. In addition, the advantage of reduced segregation of the stated composition of the white metal is particularly evident in cast alloys.

For a better understanding of the invention, this will be explained in more detail with reference to the following description and the embodiments specified therein.

By way of introduction, it should be noted that the location information chosen in the description, such as. up, down, laterally, etc. related to the embodiment of the multi-layer plain bearing described immediately and to be transferred to the new situation in a change in position mutatis mutandis.

All information in the description of compositions are to be understood in wt .-%, unless expressly stated otherwise.

Further refer to information on standards on the filing date of the present application latest version, unless expressly stated otherwise.

The invention relates to a metallic multilayer sliding bearing element, in particular a multilayer radial plain bearing element. This has a metallic, radially outer support layer (also denoted as a reverse metal layer), on which a sliding layer is applied to the radial inner surface. In the simplest, preferred embodiment, the multi-layer sliding bearing element consists of these two layers, so that therefore the sliding layer is connected to the support layer.

It is also possible that the sliding layer is arranged directly on a support element which forms in particular the support layer. This direct coating is used for example in connecting rods.

Optionally, at least one further layer can be arranged between the support layer and the sliding layer, for example a bearing metal layer and / or a bonding layer and / or a diffusion barrier layer.

The multi-layer sliding bearing element forms together with at least one other sliding bearing element - depending on the structural design may also be present more than another sliding bearing element - a sliding bearing, as is well known. It is preferred that during operation of the sliding bearing higher loaded sliding bearing element formed by the sliding bearing element 1 according to the invention, that is, for example, in the main bearing, the lower half shell or in the crosshead, the upper half shell. However, there is also the possibility that at least one of the at least one further sliding bearing elements is formed by the multi-layer sliding bearing element according to the invention.

The multi-layer sliding bearing element may be in the form of a half-shell. It is also possible that the multi-layer sliding bearing element is designed as a plain bearing bush. In this case, the multi-layer sliding bearing element is at the same time the plain bearing. Further, there is the possibility of another division, for example, a third division, so that the multi-layer sliding bearing element is combined with two other sliding bearing elements to form a sliding bearing, wherein at least one of the two other sliding bearing elements may also be formed by the multi-layer sliding bearing element. In this case, the multi-layer sliding bearing element does not cover an angular range of 180 ° but an angular range of 120 °.

However, other geometric designs of the multi-layer sliding bearing element are also possible. For example, this may be a thrust ring, a thrust bearing, etc.

The multilayer sliding bearing element is used in particular in the engine industry or in engines.

The backing layer is preferably made of a steel, but may also be made of other suitable materials, e.g. a bronze.

The materials for the optionally present further layers may be formed or assembled according to the prior art. Reference is made to the relevant prior art.

The sliding layer consists of a white metal, ie an Sn-Zn alloy. The proportion of zinc is selected from a range of 35 wt .-% and 50 wt .-%. In addition, the sliding layer contains between 2% by weight and 8% by weight of copper. The remainder to 100 wt .-% forms the tin.

It should be noted that the white metal may also contain conventional impurities derived from the production of the metals from which the white metal is produced. The respective proportions of the metals in the compositions of the sliding layer mentioned in this description thus optionally comprise these impurities.

Preferably, the proportion of zinc in the sliding layer between 39 wt .-% and 47 wt .-%, in particular between 42 wt .-% and 47 wt .-%.

It is envisaged that the proportion of copper between 2 wt .-% and 8 wt .-% copper. Preferably, the white metal in this embodiment contains between 4 wt .-% and 7 wt .-% copper.

The overlay thus consists of the metals tin, zinc and copper and any impurities present.

According to another embodiment of the multi-layer sliding bearing element can be provided that a proportion of at least 50%, in particular at least 65%, of the grains of the total zinc content is present with a maximum particle size of 250 pm. The grain size of the zinc grains is preferably between 30 μm and 150 μm, in particular between 30 μm and 100 μm. The grain size is determined according to DIN EN ISO 643.

Preferably, the white metal overlay is produced by a casting process, in particular by a centrifugal casting process, or deposited on the corresponding layer. The white metal is thus preferably a casting alloy, in particular a centrifugally cast alloy.

In the course of evaluating the usefulness of the multilayer plain bearing, the compositions shown in Table 1 were prepared and tested. The details of the composition are to be understood in% by weight.

Two-layer sliding bearings were produced in each case, wherein a steel grade C10 was used for the support layer. The infusion of the white metal overlay was carried out with the following parameters:

Alloy: Casting temperature 600 ° C

Steel blank: at 350 ° C hot-dipped steel blank Table 1: Example compositions of the white metal overlay:

(1) HB2.5 / 31.25: Brinell hardness, ball diameter 2.5 mm, test load 31.25 p (2) Rp0.2: 0.2% yield strength in [MPa] [0041] ( 3) HM07 is a commercially available white metal alloy which in addition to tin a total of 8.5 wt .-% other alloying elements (7.5 wt .-% antimony, 3.5 wt% copper, 0.2 wt -% nickel, 1 wt .-% zinc).

(4) RP0,2 Relative to HM07 As can be seen from Table 1, the white metal overlay has significant cost advantages over HM07. An alloy variant with 50 wt% tin, 43 wt% zinc and 7 wt% copper costs 50% less compared to HM07. In combination with steel, the cost advantage is reduced to approx. 20%.

The zinc is preferably present in the overlay largely homogeneously distributed. By broadly meant that a deviation of the number of zinc grains per unit volume (1 cm3 alloy) of 3% is allowed.

As stated above, it is advantageous if a proportion of at least 50%, in particular at least 65%, of the total zinc content is present with a maximum particle size of 250 μm. The grain size of the zinc grains is preferably between 30 μm and 150 μm, in particular between 30 μm and 100 μm. This is achieved by grain-refining elements from the group AI, Ag, As, Se.

Claims (4)

claims A multilayer sliding bearing element comprising a supporting layer and a sliding layer, wherein the sliding layer consists of a white metal comprising the elements tin, zinc and copper, wherein the proportion of zinc between 35 wt .-% and 50 wt .-%, characterized in that the Proportion of copper between 2 wt .-% and 8 wt .-% and the rest forms tin. 2. multilayer sliding bearing element according to claim 1, characterized in that the proportion of zinc between 39 wt .-% and 47 wt .-% is. 3. multilayer sliding bearing element according to claim 1 or 2, characterized in that a proportion of at least 50% of the total zinc content is present with a maximum particle size of 250 pm. 4. multilayer sliding bearing element according to one of claims 1 to 3, characterized in that the white metal is a cast alloy, in particular a centrifugal casting alloy. No drawings for this