DE8119463U1 - Curved plastic plain bearing bushing - Google Patents

Description

/ Plain bearing bush made of bent plastic

The innovation concerns a plain bearing bush made of bent plastic. Such sockets are multiple also made from fluorine plastic.

Bearing bushes for the manufacture of plain bearings for the inclusion of rotating or axially longitudinally displaceable parts are in mass production after State of the art rolled or bent from blanks, which are made of strip or strip material by punching or cutting be cut to length. In the production of flange sleeves in particular, tubular material is also used as the starting material Material used. The production of such sockets prepares for the use of metallic material Usually no difficulties, as the metal blanks are permanent thanks to bending or rolling devices can be deformed. These bushings are after DIN 1494, pages 1-4, already standardized. In the case of plain bearing bushes, which are used to improve the mechanical behavior made of plastic with an insert or support layer made of metallic material, prepares the production after the same process also hardly any difficulties, since here too the metallic material through the

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The bending or rolling process is permanently deformed and so is the plastic material adopts the new shape together with the supporting or supporting material. (See DIN 1494, sheet 4, materials PI and P 2).

However, bearing bushings are already used in the art that consist of pure plastic without a metal support or support layer. Such sockets are often cheaper to manufacture than Bushings made of composite material, they can also be worn until their wall thickness is completely worn, before a deterioration in the coefficient of friction due to consumption of the self-lubricating Plastic layer occurs.

Bearing bushes made of thermoplastics, e.g. made of polyamide are usually manufactured by molding processes in the thermoplastic state, e.g. injection molding. Bushings made of thermoset Plastics, e.g. made of polyimide or phenolic resins, are made from powdery or granulated molding material produced by pressing and then hardened / polymerized out by thermal post-treatment.

However, plastics are also used technically, which are neither thermoplastic nor by pressing the starting material to The prefabricated part can be processed cheaply into sockets, for example polytetrafluoroethylene. Polytetrafluoroethylene (PTFE) has extremely favorable coefficients of friction and is therefore very suitable for self-lubricating plastic bearings. PTFE leaves

However, they cannot be processed in a thermoplastic state, manufacture by pressing the powdery starting material and subsequent sintering of the bushings produced in this way, too Difficulties, especially when these bushings are thin and should have high dimensional accuracy.

According to the prior art, it is already known to use composite bearings made of PTFE with a metallic support or base layer, for example made of metal mesh sintered in PTFE or made of a sheet metal base layer with an appropriately prepared PTFE layer applied to the surface, to be processed into blanks and these blanks to be sockets using bending or rolling machines to shape. The higher the proportion of plastic in the composite material, the more difficult it becomes, however, to simply roll bushings or to form bending processes from strips or blanks.

During the deformation process of metal bushings, the elastic yield point of the material is easily exceeded and the yield point is reached, resulting in permanent deformation of the starting material occurs, plastics have a considerably higher elastic yield point than metals and the limit is exceeded The elastic limit does not occur during a normal deformation process for producing a bushing. This becomes with one in itself High plastic content required for storage reasons

the forming of bushings in a cold bending or rolling process more and more difficult. Due to the elasticity of the plastic, the molded sockets spring up again and bend more or less back to the previous shape of the board. A production of massive plain bearing bushes from polytetrafluoroethylene strips or -Platinum is therefore not possible, the sockets deform after bending or rolling, -Also if they are used to reinforce the Bend will be overbend - to return almost to the starting position. One speaks here, apart from the elasticity of the Plastic, has a memory effect, i.e. the plastic takes ~ especially under the influence of heat - it reverts to the shape it had when it was made.

The object of the invention is to provide a shape ;; ^ of sockets and

to find an ancestor for making these sockets that made it allow bushings made of solid fluoroplastic to be produced by bending or rolling, without subsequent jerk deformation

f the sockets enters.

This object is achieved in that the plastic circuit board or

-Stripes during the bending or rolling process on the larger,

the bending center facing away from the side is treated so that a Provision is wholly or largely prevented. This is because of this achieves that the sheet or strip side lying on the outside during the bending, which is stretched by the bending process, through Notches or dents in its surface is enlarged so that thereby the bending of the material is strengthened and fixed will. Through the notches on the outside of the socket that

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are made simultaneously with the bending or rolling process, the material is so stressed in this area that the The elastic limit is exceeded and flow occurs. This fixes the stretching of the outer area of the caused by a stretched layer of the board material and the socket produced in this way no longer tends to return to its original position to take again. The embossing process for producing the notches, dents or grooves can be promoted by this, that the tools used for this purpose have an elevated temperature.

The method can also be used for the production of plain bearing bushes which have a collar pointing outwards from the center of the bushing on one or both sides. These so-called "flange bushings ¹¹ are often required to fix the bushing in the axial direction and / or at the same time to be able to use the bushing as a thrust bearing in the longitudinal direction, for example for TUr hinge bearings in which the weight of the TUr rests on the collar of the bushing .

When forming the collar surface on a plastic socket, which according to the invention is produced, by a further bending or pressing process are also wedge-shaped or wave-shaped depressions pressed into the side of the collar surface facing away from the bending direction. It may be necessary that with increasing Width of the molded collar, the depth or number of notches seen from the socket axis increases to the outside to a corresponding To achieve enlargement of the surface and such a

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to achieve permanent deformation. Of course int it too possible to produce sockets with collars formed on both sides.

The invention is explained with reference to the following drawings. They show: FIG. 1 a plastic circuit board before the deformation process, both surfaces are smooth. Fig. 2 shows a plain bearing bush made from a plate with a parallel to Bushing axis running column. 3 shows a plain bearing bush made from a blank with an oblique to the bush axis running gap. The sockets 1 and 2 have on the socket-:

outside the notches according to the invention to increase the length of the outer bending surface. 4 shows an enlarged Section through the socket body in 4a) pointed and 4b) corrugated shape. 5 shows a flange bushing with a narrow one bent on one side Bund with corresponding notches. 6 shows a flange bushing with a wider collar and notches designed according to the invention that deform the surface Increase the covenant outwards.

It should be noted that when deforming the surface of plastic sockets with an integrally formed collar, the embossing of various Pages must be done. When bending the bushing, the notching is carried out from the outside and when bending the Federal, the notch is applied to the area that was previously the inside of the socket. It is therefore necessary that in in the case of the area of the collar to be bent in the first deformation step to manufacture the socket is not included in the embossing from the outside, but the embossing is only when molded

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of the covenant is made on the side that was previously the inner surface the socket represented. Basically, the surface must be enlarged by embossing on the area facing away from the bending center Side.

One cut from a plastic tape or from a plastic film The punched-out circuit board (1) has flat surfaces on both sides. It is made by an automatic bending machine, e.g. with the help of bent by bending punches around a bending core to form a socket. The same process can be achieved by rolling on a rolling device , whereby there is also usually a core in the center of the socket. The bending punches or the bending rollers, which make the bending of the plates have a sharp-edged one Rifflung, which occurs when the plate is deformed into the bending * center facing away side (2) impresses and thus a deformation Over the elastic limit causes it to enlarge the surface on the outside of the bushing in the form of pointed notches (3) or in the form of a tightly corrugated surface (4) is caused.

If a collar is then molded onto the socket, it remains a corresponding part of the socket body in the first deformation process without notches or waves (5). The covenant is in the subsequent Pressing or rolling process on the side facing away from the bending direction by pressing ram or a rolling device is also carried out Corrugations, grooves or waves (6) permanently deformed. If there is an embossing on a collar edge that is wider in relation to the bushing diameter is applied to increase the surface area, it is advantageous

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liable to design the embossing in such a way that the enlargement of the Surface of the deformed collar from the center of the socket seen from the outside increases. In this case the corrugations can increase in depth and width towards the outside (7) 5 or further corrugations can be inserted between the individual corrugations or corrugations (8) so that after on the outside, the number of embossments increases, but the depth of the individual deformations remains the same.

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SUMMARY

The invention enables the production of plain bearing bushes from plastic by bending or rolling plastic strips or boards to sockets, with during the bending or rolling process the plastic is deformed beyond its elastic limit and the plastic circuit boards then no longer work Back deformation (opening of the sockets) tend · The piatische deformation is made by embossing notches, corrugations or grooves in the plate or strip surface on the outside of the bend achieved, whereby a fixation of the stretch occurs in the outer area of the stretched layer. By using heated This effect can be intensified with embossing tools.

Flanged bushings with a collar molded onto the plastic bushing are manufactured in a further bending or pressing process in such a way that that analog impressions are made in the now, outer collar surface during the deformation. To the outwardly increasing To compensate for the enlargement of the surface of the collar, the embossments increase in width and depth radially outwards to or with the same width and depth, the increases

Number of impressions radiating outwards.

Claims (7)

Protection claims 1. Plain bearing bush made of bent plastic, characterized in that the bush on its outside (2) has molded or embossed depressions (3, 4). 2. plain bearing bush according to claim 1, characterized in that the depressions are designed as a wave-shaped or notch-shaped Grooves (3, 4) are formed in a direction at least approximately parallel to the socket axis get lost. 3. plain bearing bush according to claim 1 or 2, characterized in that that it is designed as a collar socket and that the collar is molded on its outside with or embossed depressions (6,7,8) is provided. 4. plain bearing bush according to claim 3, characterized in that the provided on the outside of the federal government Depressions are designed as corrugated or notch-shaped grooves (6, 7, 8) running in the radial direction are. 5. plain bearing bush according to claim 3 or 4, characterized in that that the recesses (3, 4) provided on the cylindrical part only extend up to the collar. 6. plain bearing bush according to one of the preceding claims, characterized in that the width and / or depth the recesses (4) provided in the federal government increase towards the outside. 7. plain bearing bush according to one of claims 3 to 6, characterized in that the number of recesses (8) provided on the collar in the outer surface area of the Federal is larger than the inner surface area.