DE19929412A1 - Bearing element for a thrust bearing takes the form of a thrust pad which together with its lining is made of a reinforced plastic material - Google Patents

Abstract

The bearing element (1) for a thrust bearing (10), comprising a thrust pad (2) and its lining (3) of a reinforced plastic material, is characterized by the fact that the thrust pad itself also consists of a reinforced plastic material.

Description

Technical field

The invention relates to a bearing element according to the preamble of first claim.

State of the art

The bearing elements of slide bearings of large machines, in particular Drawer bearings of generators essentially consist of a bearing plate and a pad made of a material with a low Coefficient of friction. Usually is used as a support for the bearing element White metal (Babitt) used. White metal pads can be simple be repaired and replaced. Furthermore, the white metal can rub hard into the Pick up the surface without damaging the rotor. White metal points has a relatively low melting point, above this temperature it will Camp destroyed. Oil is therefore used as a lubricant and coolant when starting and shutting down the generator with high pressure through the Bearing elements are pressed into the bearing to create an oil film between the To produce white metal and the rotor surface.

From the publication "PTFE Thrust Bearings for Hydro Generators and their Application to Dinorwig & Ffestiniog Pumpecl Storage Power Plants, UK ", disclosed at Hydro Vision 98, Reno Nevada, USA  Drawer bearing elements known from hydrogenerators, the support from Polytetrafluorethylene (PTFE) exists. Polytetrafluorethylene is better known under the trade name "Teflon". PTFE shows compared to bearings White metal has lower thermal conductivity properties and a lower one Coefficient of friction. Measurements have shown that the oil film between the PTFE bearing and the rotor surface with the same load is larger than with white metal. Therefore, the maximum load bearing capacity for PTFE bearings are in the order of 5 to 6.5 MPa and even up to 10 MPa, in Compared to 3.5 MPa for white metal bearings. Thanks to the deep The coefficient of friction must be added when starting and shutting down the generator When using PTFE bearings, the oil should not be put under high pressure in the bearing are pressed, which simplifies and reduces the cost of the system.

Due to the different thermal and mechanical properties of the Bearing plate made of metal and the support made of PTFE is the attachment of the Problem on the bearing plate problematic. Especially because of the different Thermal expansion during heating places high demands on the Connection between the plastic pad and the metallic bearing plate posed. To get a good connection between the support and the plate, an intermediate layer of copper wire interposed. The copper wire is layered and balled up to create a kind of copper wire bed, on which the PTFE layer is placed and by means of hot pressing with the Copper wire bed connected. The PTFE flows through the hot pressing in one Transition area in the turns of copper wire and connects mechanically with the copper wire. The composite made of copper wire and PTFE is connected to the bottom using the copper wire metallic bearing plate connected, this connection z. B. by soldering can be done. This creates a layering of metallic bearing plates, Copper wire bed, PTFE. Such a connection between the bearing plate and However, edition has very imprecise and unpredictable  Connection properties result because the PTFE layer is not everywhere penetrates evenly into the copper wire bed. The stiffness is therefore further the PTFE layer is not uniform over the surface of the bearing element distributed. This leads to relatively short lifetimes of the bearing element and to inaccurate statements about the lifespan.

However, the mechanical properties of PTFE are also strong temperature-dependent and PTFE has a great tendency to thermal Expansion and creeping up even at low temperatures. Another one The problem is the removal of the surface. To avoid these disadvantages Attempts have already been made with bearings made of reinforced PTFE. The PTFE can be reinforced with carbon or glass fibers or graphite.

In "Operation and Technical Analysis of EMP Segments", translation of a Chinese script by Prof. Shen When Yi, Committee of the Three Gorges Project, were made of plastic and composite bearing segments Examined metal. PTFE bearing pads were examined, whereby the PTFE as reinforcement glass or carbon fibers were added. Thereby should include the creep properties, the yield strength and the thermal expansion of the camp can be improved. By adding reinforcing materials However, the coefficient of friction is also increased and thus the removal of the Surface. As a lubricant and coolant, oil with a high Pressure through the bearing elements can be pressed into the bearing, causing the bearing more expensive.

Weighing up the advantages and disadvantages of the bearings results from the above document that PTFE bearing pads with reinforcing materials overall have worse properties than pure PTFE coatings and therefore should not be used.  

Here too, however, result from the different thermal and mechanical properties of the bearing plate made of metal and the support reinforced plastic the same connection problems between the reinforced plastic pad and the metallic bearing plate. this leads to also at relatively short lifetimes of the bearing element and inaccurate Statements about the lifespan.

Presentation of the invention

The invention has for its object in a bearing element of the beginning mentioned type the construction of bearing elements when using to simplify and improve reinforced plastic bearing pads.

According to the invention, this is achieved by the features of the first claim reached.

The essence of the invention is therefore that the plate and the entire segment structure also consists of a reinforced plastic.

The advantages of the invention can be seen in the fact that the advantages can be exploited by reinforced plastic bearing pads and the Pad can still be securely connected to the bearing plate. Through the Use of reinforced plastic bearings will cause thermal deformation of the bearing element reduced, the construction of the bearing element simplified and thereby increases the reliability of the construction.

Further advantageous embodiments of the invention result from the Subclaims.  

By using thermoplastic composite materials, the Bearing elements can be produced particularly cheaply by hot pressing.

It is also advantageous on the pad made of reinforced plastic molecular bond a sliding film to reduce the coefficient of friction of the To apply plate support. Through the molecular connection of the sliding film with the sliding film is also liable if the additional use of oil is used in the warehouse reliably on the edition. By using bearings reinforced plastic with a molecularly attached to the pad The lubricating film needs the oil when starting and shutting down the machine to be stored not be pressed into the bearing with high pressure, which continues the system simplified and cheaper.

It is particularly expedient if a disulfide is used as the sliding film.

Brief description of the drawing

In the drawing, an embodiment of the invention is schematic shown.

Show it:

Figure 1 shows a partial longitudinal section through a drawer.

2 shows a partial cross section through a bearing with multiple thrust bearing elements.

Figure 3A shows the enlarged detail II of Figure 1 with different support and plate..;

FIG. 3B shows the enlarged detail 11 from FIG. 1 with a support and plate made in one piece.

They are only the elements essential for understanding the invention shown.

Way of carrying out the invention

In Fig. 1 and 2, a thrust bearing 10 is illustrated, which comprises a rotor 6 and the thrust bearing elements. 1 A drawer bearing element 1 usually consists of a plate 2 and a plate support 3 . The plate support 3 is firmly connected to the plate 2 , for example the plate support can be connected to the plate by hot pressing. The thrust bearing element 1 is rotatably supported relative to an abutment 11 via a pivot bearing 5 . The drawer bearing 10 consists of several drawer bearing elements 1 , which are regularly distributed around a rotor axis 9 , see FIG. 2. The entire drawer bearing 10 is covered with oil 8 , an oil film of thickness h being formed between the rotor 6 and the drawer bearing element 1 . The thickness h and the pressure distribution of the oil film and an angle α of the thrust bearing element 1 with respect to the rotor is dependent on the load 7 of the rotor and its speed and the position of the rotary bearing 5 relative to the bearing element 1 and on the viscosity of the oil, whereby by the shear forces heat is produced in the oil film. The heat generated can be dissipated via the oil.

The plate 2 and the plate support 3 consists of a plastic which is reinforced with a filler. Various thermoplastics can be used, which are filled with filling materials such as carbon and glass fibers or with graphite, etc. A well-known material is for example "Zymaxx", which consists of polytetrafluoroethylene (PTFE) and embedded carbon fibers. Compared to pure PTFE, this material has improved creep properties, a higher yield strength and lower thermal expansion. Compared to a drawer bearing element with a white metal support, the thermal deformation of the drawer bearing element is thus reduced, which significantly improves the construction of the drawer bearing element. Furthermore, the improved creep properties compared to PTFE make the behavior of the drawer bearing element more predictable and reliable, since the creeping of the plate support essentially no longer has to be taken into account.

As already mentioned, a disadvantage of this material is the increased coefficient of friction compared to pure PTFE. Therefore, a sliding film 4 , see FIGS. 3A and 3B, is applied to the plate support 3 and this sliding film is molecularly connected to the plate support. The molecular connection is achieved through the appropriate choice of the sliding film material. As a sliding film material, for example, disulfides can be used, which form a molecular bond with the plate support without additional binders. A particularly preferred disulfide is tungsten disulfide (WS ₂ ), which is known, for example, under the brand name "Ultralube" or "Dicronite". The coefficient of friction of this material is less than 0.03 and it can easily be applied to the substrate, and as mentioned above it forms a molecular bond with the substrate. However, a molybdenum disulfide can also be used, which has become known, for example, under the brand name "Petromoly".

However, it is also possible to use a layer of PTFE as the sliding film, the z. B. can be applied to the substrate by means of plasma technology. Also here, of course, the above disulfides can be applied to the sliding layer made of PTFE be applied.

By applying the sliding film to the plate support, the Friction coefficient of the drawer bearing element is drastically reduced and there will be  even better values than when using pure PTFE. By The molecular connection of the sliding film and the plate support guarantees that the sliding film is also not removed when starting and Shutting down the system no oil with pressure entered in the drawer becomes.

By using a molecularly connected to the plate support Sliding film can also use reinforced plastics other than PTFE Plate support can be used. Although these materials have a higher Coefficient of friction can have as reinforced PTFE, is due to the Using the sliding film reduces the friction sufficiently. So can any thermoplastics that have the appropriate mechanical and thermal requirements are used. these are preferably aromatic plastics, in particular polyphenylene sulfide (PPS), Polyetherimide (PEI) or polyetheretherketone (PEEK). As a reinforcement material carbon fibers or glass fibers or other fillers are also preferred here used because the resulting composite material is very small has thermal expansion coefficient which is very advantageous. PEEK is usually around 400 ° C, PPS around 340 ° C and polyimide around 420 ° C processed.

These plastics mentioned above can of course also be used for the plate 2 , in particular since the coefficient of friction does not play a role for the plate 2 .

According to FIG. 3A, the plate 2 can be made of other reinforced plastic as the support 3. Particular attention must then be paid to the plastics used in order to achieve an adequate connection between the two layers.

The solution according to FIG. 3B where the plate and the support are made in one piece from the same reinforced plastic is particularly advantageous. This avoids any binding problems and significantly increases the service life of the bearing element. By using a sliding film, the mechanical and thermal requirements of the bearing element can be achieved by any combination of reinforcing material and plastic matrix.

Of course, the invention is not limited to that shown and described Embodiment limited. The bearing elements described here can can of course also be used in a radial bearing. The bearing elements are then arranged around the circumference of the rotor and according to the circumference of the rotor. Other sliding films can also be used a sufficient connection with the plate support and a sufficiently deep one Have coefficients of friction.

Reference list

1

Drawer bearing element

2nd

plate

3rd

Plate support

4th

Sliding film

5

Pivot bearing

6

runner

7

load

8th

oil

9

Rotor axis

10th

Drawer bearing

11

Abutment
h oil film thickness
α angle

Claims (7)

1. bearing element ( 1 ), in particular for drawer bearings ( 10 ), comprising a plate ( 2 ) with a plate support ( 3 ) attached thereon made of a reinforced plastic, characterized in that the plate ( 2 ) also consists of a reinforced plastic. 2. Bearing element according to claim 1, characterized in that the plate ( 2 ) and the plate support attached to the plate ( 3 ) are made in one piece from the same reinforced plastic. 3. Bearing element according to one of claims 1 or 2, characterized in that the reinforced plastic material of the plate ( 2 ) and / or the plate support ( 3 ) is PTFE or an aromatic thermoplastic. 4. Bearing element according to one of claims 1 to 3, characterized in that the reinforcing material of the plate ( 2 ) and / or the plate support ( 3 ) is carbon or glass fiber or graphite. 5. Bearing element according to one of claims 1 to 4, characterized in that a sliding film ( 4 ) is applied to the plate support ( 3 ) by molecular bonding to reduce the coefficient of friction of the plate support ( 3 ). 6. Bearing element according to claim 5, characterized in that the sliding film ( 4 ) is a disulfide. 7. Bearing element according to claim 6, characterized in that the sliding film ( 4 ) is a tungsten or a molybdenum disulfide.