DE2818184C3 - Process for the production of a layered material with a low-friction surface for shaped workpieces - Google Patents

Description

The invention is based on a method according to the preamble of claim 1.

Low-friction plain bearings, the main component of which is a fluorine-carbon-hydrogen polymer, e.g. B. Polytetra- * o fluoroethylene is known.

From DE-OS 22 06 400 a method is known in which a lacquer-like, solvent-soluble polyimide is mentioned as a binder, this polyimide lacquer with polyimide powder and other additives, eg. B. also PTFE, mixed and applied to a carrier material. A mixture of PTFE particles, polyimide particles and, if necessary, substances that improve the sliding properties are prepared into a paste using polyimide varnish, and this paste is applied to the carrier material. It is essential in this known method that the polyimide varnish component also forms after crosslinking and curing an adhesive or bonding agent that holds together the solid particles contained in the layer and the thus formed ⁵ S-friction layer to the carrier material retains This process has the deficiency that on the one hand the paste prepared with polyimide varnish naturally has a sticky consistency and therefore causes difficulties in its processing. In this process it is therefore necessary that the applied mass must first be cured before a layer formed in this way can even be leveled and processed. This makes the manufacturing process much more difficult and expensive. This paste, which is to be made up with polyimide varnish, is not suitable for being pressed into the rough ground of a carrier material. Rather, it must be prepared with such consistency that they are in the rough ground of the Impregnate carrier material so can soak. It follows from this that pressing into the rough ground and equalizing the layer thickness cannot be carried out. Only after the layer formed from polymer alloy has been extensively crosslinked of the polyimide component is pre-cured, a Calibration can be carried out. However, this is only possible through machining, in particular through Peel off, possible. This cutting treatment is on the one hand expensive and on the other hand also leads to Loss of material

Finally, with the layer materials presented according to DE-OS 22 06 400 hi, because of the use of polyimide lacquer, there is only limited cavitation and wear resistance and only one limited temperature resistance achievable.

The invention is based on the object of designing a method of the type mentioned so that the Coating material without additional non-cutting or cutting operations for further processing in Plain bearing is suitable whereby the process sequence should be simplified overall.

This object is achieved with the measures specified in claim 1

A paste-like mass is thus produced starting from a PTFE suspension. This paste-like substance The mass is so stable that it is actually pressed into the rough ground of the carrier material and can be shaped as a layer. This enables the application thickness to be equalized before the polyimide component is crosslinked. The crosslinking of the polyimide component can are initially kept within such small limits that the coating material still needs to be calibrated the final crosslinking is possible to achieve its desired final thickness by pressing and temperature control or curing takes place with simultaneous calibration to the desired final thickness machining, for example peeling the layer material, to the desired thickness, in other words, a relatively expensive operation that is also necessarily associated with a loss of material

The interaction of this polymer alloy made of PTFE and polyimide and possibly additives increasing the cavitation resistance and wear resistance with the anchoring of this polymer alloy in a rough ground result in previously unattainable cavitation resistance and wear resistance of such layered materials. It is surprising all the more, will be introduced as in the known bearing materials based on PTFE and lead powder into a porous sintered bronze layer by rolling at 300 ⁰ C, does not have sufficient cavitation could be achieved. It can be assumed that PTFE, due to its anti-adhesive property, has a satisfactory bond with the porous sintered layer, i.e. the mechanical clamping of the rolled-in PTFE / Pb mixture is not sufficient to ensure sufficient bonding between the sintered bronze powder and the PTFE / Pb mixture in the event of cavitative loading .

For example, it is provided that the method runs continuously, with the application of the pasty mass on the carrier material by rolling under Covering the rough ground takes place.

As in fatigue tests, the layer materials produced by the process show

servohydraulic test equipment and tests in the Practice was found with high, cavitative stress no deficiency symptoms. By using the heavy-duty polyimide molding compound or - molding compound and the aggregate is a layer material with a high level of cavitation resistance generated

The following solid compositions can be used to form a pasty mass:

III

example 1

40% by volume PTFF (density 22 g / cm ³ ) 40% by volume polyimide (density 13 g / cm ³ ) 20% by volume MoS ₂ (density 4.8 g / cm ^J )

Example 2

50% volume fractions PTFE (density 22 g / cm ³ ) 30% volume fractions polyimide (density 13 g / cm ³ ) 10% volume fractions polyphenylene sulfide

(Density 13 g / cm ³ ) 10% by volume graphite (density 2.4 g / cm ³ )

Example 3

50% by volume PTFE (density 22 g / cm ^J ) 30% by volume polyimide (density 13 g / cm ³ ) 20% by volume PbO (density 9 g / cm ³ )

Example 4

30% volume parts PTFE (density 2.2 g / cm ³ ) 50% volume parts polyimide (density 13 g / cm ³ ) 10% volume parts homopolyester

(Density 135 g / cm ³ ) 10% by volume Laves phases (density 9 g / cm ³ )

Laves phases from Römpps Chemie-Lexi-. »■> kon (1973), page 1941 are known intermetallic compounds of the formal composition AB ₂ with a certain affinity between the atomic structures and a favorable atomic radius ratio of the partners, namely optimal atomic radius ratio A: B = 1.225. 4 »

Example 5

40% volume fractions PTFE (density 2.2 g / cm ^J ) 40% volume fractions polyimide (dense; 13 g / cm ³ ) 20% volume fractions Pb (density 11.34 g / cm ^J )

Example 6

40% by volume PTFE (density 22 g / cm ³ ) 60% by volume polyimide (density 1.3 g / cm ³ )

50

15th

2 (J

25th

. "I.

The above-mentioned polyimide content can be crosslinked in an inductively heated, temperature-controlled continuous furnace above the gel point of the PTFE at approx. 330 ° C to 380 ° C.

Some exemplary embodiments of the invention are described below with the aid of schematic drawings. There are:

F i g. 1 shows a schematic arrangement in side view of a plant for the continuous production of a Layer material in tape form, in particular a "" plain bearing layer material;

F i g. 2 to 8 are schematic representations of some variants of the layer material in cross-sectional form.

To Fig.!, Variant 1: ₍ , s

A carrier material 1, e.g. B. consisting of a 0.75 mm thick, copper-plated steel strip on both sides 21 with a sin; "Frame 23 made of tin-containing copper alloy 03mm thick, see Fig. 2, is constant from an unwinding device 2 via a z. B. trained as a roller conveyor Transport device 3 supplied to applicator rollers 4

E: ne pasty mass, e.g. B. according to the solid composition of Example 1, consisting of 40% by volume PTFE, 40% by volume PI and 20% by volume MoS ₂ . is applied continuously in position 5 and then pressed into the porous sintered framework 23 of the carrier material 1 by the application rollers 4

The required application quantity is regulated by the pressure applied by the application rollers 4.
The carrier material 1 filled with pasty mass is then passed on to a leveling roller system 6. 01 mm is present

The next step in the operation is curing ζ. B. in an inductively heated, temperature-controlled continuous furnace system 7 for this pasty mass at about 330 ⁰ C to 380 ° C, above the gel point of the PTFE to carry out the crosslinking of the polyimide.

After leaving the continuous furnace system 7, the still warm layer material is in a temperature-controlled calibration rolling mill 8 pressed to its final thickness and then in a For example, water- or air-powered cooling zone 9 is cooled and finally on a reel i0 wound up into a roiie.

To fig. 1, variant 2:

As a carrier material 1 is z. B. a 1.5 mm thick domed aluminum strip 27 with 0.5 mm depressions and approx. 40 total surface area - similar to FIG. 4 or 5 - printed with a pasty mass according to example 4 in the depressions 28 or 29, additionally provided with an AuPage layer 25 of 0.01 mm to 0.015 mm thickness and at approx. 260 ⁰ C in the inductively heated, temperature-controlled flow- Furnace tank 7 hardened.

To Fig. 1, variant 3:

As a carrier material 1 is z. B. an approx. 1 mm thick, uncoppered carbon steel strip 21 constantly fed from the unwinding device 2 to the discharge rollers 4, from a second Unwinding device 2a is a fabric web 26, for. B. made of polyimide, F i g. 3. also the application rollers 4 supplied.

In terms of process technology, as in variant 1, a pasty Masro according to Example 1 is rolled into the fabric web 26 in such a way that only a protruding layer 25 of the pasty mass of a maximum of 0.005 mm is on the surface and again at an oven temperature of approx. 330 ⁰ C to 335 ⁰ C is cured.

To Fig.!, Variant 4:

As a carrier material 1 is a with z. B. square breakthroughs - similar to the F i g. 6 - provided, approx. 0.8 mm thick aluminum tape 30

fed from the unwinding device 2 to the applicator rollers 4, with a pasty mass after the example 2 filled in the openings 31 and at the same time a double-sided uniform layer 25 formed in a thickness of 0.005 to 0.02 mm. The oven temperature is approx. 360 ° C to harden.

To Fig. 1, variant 5:

Analogous to variant 4, this time the carrier material 1 is a porous, tin-containing, copper-alloyed one Sintering frame 23, such as. B. in Fig. 7, with a thickness of about 03 mm fed. Instead, a fabric tape 36 or fabric tape of a corresponding thickness can also be supplied - as shown in FIG. 8 can be seen -.

According to FIG. 2, a steel strip 21 is provided with a copper plating 22 on one side. A sintering frame 23 made of tin-containing copper alloy is attached to this 2n copper plating 22. The steel strip 21 can, for example, be 0.75 mm thick and the sintered framework 23.3 mm thick. The sinter framework 23 is completely filled with a polymer alloy 24, this tf polymer alloy 24 also forming a support layer 25, for example 0.01 mm thick, over the sinter framework 23.

While in the example of FIG. 2 the sintering frame 23, representing the rough ground, over the copper plating Jo layer 22 is firmly connected to the steel strip 21. i.e. the carrier material, and thus the polymer alloy 24 serves more or less to fill out the sintering frame 23, in the example of FIG. 3 a Fixed connection created at the interface between steel "band 21 and polymer alloy 24. The Rauhgrund is in this example in the form of a fabric web 26 or scrim made of polyamide fibers, Polyester fibers such as PETP or glass fibers embedded in the polymer alloy 24, specifically in the area the interface between the polymer alloy 24 and the steel strip 21.

4 shows an aluminum strip 27 with depressions 28 which are designed in the shape of a truncated cone are. According to FIG. 5, this is the supporting structure 4 ^ Fabric-serving aluminum strip 27 is provided with dome-shaped depressions 29. In both cases they are Wells 28 and 29 filled with polymer alloy 24. About the aluminum tape 27 is with the Polymer alloy 24 also formed an overlay layer 25 sn, which in this example has a thickness of 15 to 20 μίτι should have. The thickness of this support layer 25 can, however, be up to 50 μπι in the same example.

In the example of FIG. 6, an aluminum strip 30 with openings 31 is provided. This at the same time as In addition to the filling of its openings 31, the aluminum strip 30 serving as the carrier material and rough ground also provided with a layer 25 made of polymer alloy 24 on each side.

Other possibilities for a self-supporting band-shaped formation of the rough ground are shown in FIGS. 7 and 8 shown. According to FIG. 7, a sintered belt 33 made of tin bronze is provided, which is also the carrier material and rough ground. This sintered belt 33 is interspersed with polymer alloy 24 and on <·> Coated on both sides with this polymer alloy 24, so that there are overlays 25 with a thickness between 5 and 20 µm.

In the example of Figure 8, the self-supporting Rauhgrund formed by a fabric web 36 or fabric web, which in its structure is the same as the Fabric web 26 according to FIG. 3 can be. This fabric web 36 is also made entirely of polymer alloy 24 filled in and covered on both sides with a layer 25 made of polymer alloy 24, the thickness this support layers 25 can in turn be up to 50 μm, preferably up to 20 μm. For example In this case, two support layers 25 of 20 μm thickness can be provided.

The composition of the polymer alloy 24 for all of these examples can be selected from those already given above Examples of recipes can be selected directly or modified.

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Claims (3)

1 claims: 1. Process for the production of a laminate material with a low-friction surface for molded Workpieces by coating one or both sides of a carrier material with a rough base with a pasty mass, the solids of which are 10 to 90% by volume of polytetrafluoroethylene (PTFE), 10 to 90% by volume of polyimide and 0 to 20% by volume of additives which increase cavitation and wear resistance, thereby characterized in that the pasty mass by mixing in exclusively thermosetting polyimide with a grain size of ^ ΙΟΟμίτι, alone or together with the additives, in an aqueous dispersion of PTFE with a spherical structure and a grain size between 0.1 μτη and 1 μπι and Precipitation is formed and that this pasty mass applied to the rough ground in the desired thickness, pressed in and then tion of the polyimide is solidified under the action of heat, whereupon the still warm layer material pressed to its final thickness and then cooled. 2. The method according to claim 1, characterized in that an aqueous PTFE dispersion 20 to 50% by mass is assumed. 3. The method according to claim 1, characterized in that the crosslinking of the polyimide in an inductively exposed, temperature-controlled continuous furnace system above the gel point of the PTFE at 330 ⁰ C to 380 ⁰ C is carried out.