DE3326316A1 - Sintered-metal bearing bushes with lubricant pockets arranged on the inner running surface and process for their production - Google Patents

Abstract

Sintered-metal bearing bush 1 with depressions provided on the inner running surface 2, the said depressions serving as lubricant pockets for receiving lubricant. The depressions are preferably 0.2 to 0.5 mm deep and may be hemispherical or elongate. They are preferably arranged symmetrically distributed over the surface. The sintered-metal bearing bushes are produced by the usual sintered-metal technique, and subsequently a plurality of depressions are simultaneously pressed into the inner running surface of the bearing bush by means of an impressing tool which is introduced into the bush and activated after aligning with a ram. As impressing tool, use is preferably made of a hollow-cylindrical device having balls which are arranged radially movably and which are pressed outwards, at least partially beyond the outer circumference of the hollow cylinder into the inner running surface of the bush to be worked, by a ram introduced into the holding device in the direction of the cylindrical axis. <IMAGE>

Description

The invention relates to sintered metal bearings

bushes with recesses arranged on the inner running surface for the absorption of higher viscosity lubricants and a process for their production.

Plain bearings made of sintered metal, for example sintered iron or sintered bronze, which have a pore space of around 15 to 30% (based on the total volume of the bearing bush) are known in principle.

By filling the pore space with a lubricant self-lubricating and maintenance-free plain bearings that are now a solid Have conquered their place in modern machine and equipment manufacturing. Due to their manufacturing technique, the non-cutting shaping by pressing and, if necessary, calibration, are kept to a minimum In terms of material use, ready-to-install bearings with high dimensional accuracy disposal that do not require any further work from the user.

In many cases, the pore space of these sintered bearing bushes is sufficient Lubricant reservoir off. Since highly viscous lubricants do not get out of the pore space released, only low-viscosity lubricants can be used for its filling will. In those cases in which, under operating conditions, the capillary forces do not sufficient to provide the amount required to form a lubricant film To release the pores, additional or different lubricant reservoirs are required. This is also the case when a low-viscosity lubricant is used due to high surface pressure does not form a film and highly viscous lubricants have to be used.

In DE-OS 29 13 708 bearing bushes are described, on the supporting one There are tread lubricant pockets for receiving a lubricant.

The bearing bushes are made from a correspondingly stamped sheet metal strip rolled. The material displaced into the bushing during non-cutting forming before rolling forms the knobs on the outside. The manufacturing tolerances of However, rolled bushings are not sufficient for some purposes.

From DE-OS 16 25 650 are sintered plain bearings with lubricant storage known. Such additional storage space is created, for example, by that the bearing housing starting from the bore that is to receive the bearing, a annular indentation received prior to insertion the bearing bush is filled with lubricant.

Either a suitable bearing grease or one with lubricating oil can be used soaked felt strips are used. The inserted bearing bush closes the storage space from, however, with its porosity allows the replacement used up or lost lubricant from the reservoir.

The incorporation of a cavity serving as a lubricant reservoir into the bearing housing, for example by turning back, provides an additional, cost-causing operation.

Therefore, the lubricant reservoir was designed as a recess or circumferential Annular groove in the outer circumferential surface of bearing bodies manufactured using the injection molding process educated. In this document it is stated that it is done with the usual pressing processes is not possible to produce moldings undercut on all sides, so that a Machining shaping is required as a further step.

However, these known bearings have the major disadvantage that the lubricant pocket is on the outside of the bushing, and if it is missing, sufficient Capillary forces do not have enough lubricant on the inner running surface the bush is transferred, there is no formation of the required lubricant film despite the lubricant reservoir.

The object of the invention is to provide a sintered metal bearing bush and a To create a process for their production that eliminates the disadvantages of the known bearing sockets with lubricant supply and thus the known properties of the sintered bearing bushes improved.

This task is solved by sintered metal bearing bushes with lubricant pockets, which are characterized in that depressions on the inner running surface for receiving lubricants are available. With the lubricants it is themselves. preferably those with a higher viscosity.

The invention also includes a method of making sintered metal bushings with lubricant pockets, which is characterized in that one in the interior Running surface of the socket several recesses by means of one introduced into the socket and after aligning the activated embossing tool presses in at the same time.

A preferred embossing tool for creating depressions in the inner running surface of sintered metal bearing bushes is characterized by that in holes in the wall of a hollow cylindrical holding device radially movable Balls are arranged, which are inserted into the holding device by a cylinder in the axial direction introduced punch to the outside at least partially over the outer circumference of the hollow cylinder can also be printed.

Such an embossing tool can be used on the inner Running surface indentations that are 0.2 to 1.0 mm deep are impressed, which are considered to be Lubricant pockets lying on the running surface act. Preferably is the embossing depth 0.2 to 0.5 mm.

The depressions are preferably symmetrical on the surface arranged distributed, there are But also asymmetrical arrangements possible. The depressions are hemispherical or elongated elliptoidal educated. The wells can have different distances from each other, several wells at a short distance from one another also form a group can.

Elongated depressions can be in the longitudinal direction or along the Circumference, but also run obliquely. The number and size and location of each Recesses can meet the special needs of the plain bearing bush and the need for lubricants be adjusted. The area ratio of the indentations and the supporting surface of the The bearing bush can be varied and is used for the intended purpose appropriately selected for the socket.

The surface proportion of the depressions is preferably from 10% to 30% of the total running surface of the bearing bush.

Sintered bearings can be made of iron, ferrous materials in which iron with Copper and / or graphite is combined, or made from bronzes.

The materials enable the production of bearing bushes of different types Porosity, which can be between 10 and 30% by volume of the material. Are preferred Pore volumes of 15, 20 and 25% by volume.

Such bearings can be designed with a tolerance accuracy of IT 5 produce. Because of your Porosity is an afterthought the inner running surface of the bearing bushes possible without being displaced Material forms a bead and the smooth inner surface of the bearing bush is lost. The subsequent embossing of lubricant pockets in the inner running surface of the Bearing bushes are both thin and thick bearing bushes without any change in tolerance possible.

The manufacture of sintered metal bearing bushes with lubricant pockets takes place by making several recesses in the inner running surface of the socket by means of an embossing tool inserted into the socket and activated after alignment at the same time. The embossing tool used is preferably a hollow cylindrical one Holding device with radially movably arranged balls, which are supported by a cylinder axis direction inserted into the holding device punch to the outside at least partially the outer circumference of the hollow cylinder out into the inner running surface of the bush be pressed.

Balls have proven to be particularly suitable, movable stamping bodies proven, however, differently shaped radially movable embossing bodies can also be used Generating the depressions in the bearing bush are used. Depending on the number the movable embossing body arranged in the hollow cylindrical holding device is in an embossing process, i. H. pressing a stamp into the interior of the hollow cylindrical device, the corresponding number of wells in the Bearing bush generated by means of the movable embossing body.

However, the stamping tool can also have a smaller number of movable stamping bodies exhibit. In this case, the position of the holding device is determined after a first embossing process within the bushing to be machined by turning it around the longitudinal axis or moving it changed in the direction of the longitudinal axis and carried out another embossing process. By multiple repetitions of the embossing processes with one and the same tool after each Changes in position can increase the number of depressions to the desired extent.

There is another possibility of variation for the shape of the depressions in that the position of the embossing tool within the socket to be treated in the activated state in the longitudinal direction and / or around the longitudinal axis of the socket Shifting or twisting changes and forms elongated depressions. if after a first embossing with or without changing the position of the embossing tool in the loaded state this is relieved of pressure, the position of the embossing tool within the socket in the longitudinal direction and / or around the socket longitudinal axis by moving or twisting and then carrying out further embossing, different Combine shapes of indentations within a socket with one another, for example spherical depressions with elongated depressions or groups of the same Wells with groups of other wells. For example, it is possible a spherical recess star-shaped from slot-shaped recesses to one Group training and several such groups on the surface to arrange.

If you have to change the position of the embossing tool several times, possibly with subsequent Activation of the embossing tool executes the shape and location of the depressions to each other in the running surface of the socket can be changed and varied as desired.

Due to the inventive design of sintered metal plain bearings it is possible to provide such plain bearings with grease lubrication, which in the Running surface of the sintered metal plain bearing in lubrication pockets as a lubricant reserve is arranged, the formation of the lubrication pockets takes place according to the invention in the normal Manufacturing process for the manufacture of plain bearings with an additional stamping tool after calibrating the sockets. With a suitable number of movable stamping bodies the lubrication pockets are made in one fell swoop, so that this working method particularly suitable for mass production. But even if a multiple coinage is required, the time required for the introduction of lubrication pockets increases Relation to the total production time only insignificantly.

The embodiment of the invention of the sockets offers considerable Opportunities to improve the previous running properties of sintered metal bearings. In addition to lubrication with oil by impregnating the sintered metals, the Grease lubrication during assembly by introducing suitable, highly viscous lubricants in the Lubrication pockets take place. In addition, all material combinations are as well as additives of solid lubricants possible. If necessary, impregnation of the porous bearings with synthetic resin or other sealants provide a complete seal of the pores and only lubricants are introduced into the pockets.

The attachment of lubrication pockets is also only sintering manufacturable special forms such as spherical bearings or flange bearings are possible. Mainly However, cylindrical bearings, cylindrical bearings with a collar and so-called double bearings are used equipped with the lubricant pockets according to the invention.

Due to the high dimensional accuracy of the sintered metal technology, the Bearing bushes according to the invention the rolled, provided with lubricant pockets Bushings are superior in cases where high dimensional accuracy is required.

The invention will now be explained in more detail with reference to figures.

Figure 1 shows a cylindrical plain bearing 1 with an internal Running surface 2, in which the depressions according to the invention for receiving lubricant are introduced.

Figure 2 shows schematically the embossing device in the filling position. That Sintered metal bearing 1 to be processed is placed in the device between the upper punch 3 and the tool sleeve 4 introduced.

The lower punch 5 adjoins the tool sleeve 4. Concentric The actual embossing tool with a hollow cylindrical one is arranged in the lower punch Holding device 7 with the radially movably arranged balls 8 as an embossing body.

The stamp is already inserted into the center of the device 6, which has heels with different outer diameters.

In Figure 3, the embossing device is shown in the embossing position. The upper punch 3 has pressed the sintered bush 1 into the tool sleeve 4, and the lower punch 5 exerts a counter-pressure on the bush 1 so that it is retained is. The holding device 7 with the movable embossing bodies 8 is already in the Brought to the embossing position, but the stamp 5 is still in its starting position.

Figure 4 shows the actual embossing step. The stamp 6 is with the portion with the larger diameter is introduced into the holding device 7 and presses the arranged in the holding device 7 due to the larger diameter radially movable balls 8 outwards so that they are over the outer circumference of the holding device 7 penetrate into the inner running surface of the sintered metal bush 1 and form depressions there. A drive device is also shown schematically in FIG 9 reproduced, with which the position of the holding device 7 relative to the sintered metal bushing 1 can be changed to change the shape of the indentations.

If a multiple embossing is done with the same embossing tool should, after the first supply of the stamp 6 in the in Figure 3 reproduced position returned so that the movable embossing body 8 from Pressure are relieved, and in this position the holding device 7 relative to the sintered metal bushing 1 moved or rotated and then another embossing process, as in Figure 4, performed by pushing the punch so that the area with a larger diameter exerts pressure on the movable embossing body 8 and this shifts radially outwards.

Figure 5 shows the embossing device in the open position ready for Ejection of the sintered metal bushing provided with recesses on the inner running surface 1. The upper punch 3 has moved away from the lower punch 5, and so is the tool sleeve 4 has been withdrawn so that ejection of the sintered metal sleeve 1 is possible. The holding device 7 and the punch 6 are also withdrawn.

The embossing device to be used according to the invention consists of one Upper punch 3, a lower punch 5 and a tool sleeve 4 for storage and Holder of the socket to be machined. The actual embossing tool consists of a hollow cylindrical holding device 7 for the radially movable embossing body 8, which are preferably balls. The holding device 7 has a connecting flange for a movement device 9, with which the position of the holding device 7 fixed relative to the sintered metal bushing 1 to be treated and, if necessary, also changed can be. Changes in position by moving it lengthways or twisting around the longitudinal axis are both when the punch 6 and thus activated in the working position embossing bodies 8 possible as well as partially retracted punch 6 with not activated position of the embossing body. The hollow cylindrical Holding device 7 for the actual embossing body 8 is preferably a metal sleeve with corresponding holes to accommodate the embossing body. For example, it can are a kind of axial bearing in which the radially movable balls act as stamping bodies inserted by an embossing process and fixed in a radially movable manner. To that To enable the holding device to be inserted into the sintered metal bushing to be treated, the embossing bodies, preferably balls, do not protrude beyond the in the unloaded state Outer circumference of the holding device also, they rather protrude in this position in the interior of the hollow cylindrical holding device. By pressing a stamp, whose outer diameter is slightly smaller than the inner diameter of the hollow cylindrical Holding device, the balls are pushed radially outwards and protrude in the pressure-loaded State beyond the outer circumference of the holding device and generate in this Position of corresponding recesses in the sintered metal bearing bush coaxially surrounding the device, The hardness of the material of the stamping body depends on the strength of the one to be machined Matched sintered metal bushings. In general, hardened steel balls are used as stamping bodies sufficiently stable and firm enough.

The balls used as stamping bodies can have a diameter of 0.5 mm to 5 mm.

The distance between the individual balls in the holding device is preferably 1 mm to 10 mm. The holding device has the form of a hollow cylindrical socket a wall thickness between 0.3 mm and 10 mm adapted to the ball diameter, see above that the balls are pushed up to 1 mm beyond the outer circumference can.

LIST OF REFERENCE NUMERALS 1 sintered metal bearing bushing 2 inner running surface the bearing bush 3 upper punch 4 tool sleeve 5 lower punch 6 embossing needle or Embossing die 7 holding device 8 movable embossing body 9 device for moving and rotating the holding device

Claims (10)

Sintered metal bearing bushes with on the inner running surface arranged lubricant pockets and method for their production claims 1. Sintered metal bearing bush with lubricant pockets, characterized in that On the inside running surface there are indentations for receiving lubricants available. 2. Sintered metal bearing bush according to claim 1, characterized in that that the depressions are 0.2 to 1 mm, preferably 0.2 to 0.5 mm deep. 3. Sintered metal bearing bush according to claims 1 or 2, characterized in that that the depressions are arranged symmetrically distributed on the surface. 4. Sintered metal bearing bush according to Claims 1 to 3, characterized in that that the depressions are arranged hemispherical or elliptoidal. 5. Process for the production of sintered metal bearing bushes with lubricant pockets, characterized in that there are several in the inner running surface of the socket Depressions by means of an inserted into the socket and activated after alignment Embossing tool at the same time. 6. The method according to claim 5, characterized in that as Embossing tool arranged to be radially movable in a hollow cylindrical holding device Balls used, which are inserted into the holding device by a cylinder axis introduced punch to the outside at least partially over the outer circumference of the hollow cylinder into the inner running surface of the bushing. 7. The method according to claims 5 or 6, characterized in that the position of the embossing tool within the socket in the activated state in Longitudinal direction and / or around the longitudinal axis of the socket by moving or rotating changes and forms elongated depressions. 8. Process according to Claims 5 to 7, characterized in that after a first embossing, the embossing tool is relieved of pressure, the position of the Embossing tool within the socket in the longitudinal direction and / or around the socket's longitudinal axis changed by shifting or twisting and then executes another embossing. 9. The method according to claims 7 or 8, characterized in that g e k e n n z e i c It doesn’t mean that you can change the position of the stamping tool several times, possibly with subsequent changes Activation of the embossing tool executes and thereby the shape and / or the position of the depressions changed to one another in the running surface of the bushing. 10. Embossing tool for creating indentations in the interior Running surface of sintered metal bearing bushes, characterized in that in holes Radially movable balls are arranged in the wall of a hollow cylindrical holding device by a punch inserted into the hollow cylindrical holding device be pressed radially outward so that they are at least partially over the outer circumference the hollow cylindrical holding device protrude.