DE102016122154A1 - Plain bearing bush and method and tool for their production - Google Patents

Abstract

The invention relates to a plain bearing bush (1), which is characterized by grooves (3) which are arranged on the inner circumferential surface (2) of the plain bearing bush and together form a grid. Conveniently, the grooves (3) form a left-hand thread and a right-hand thread, with the left-hand thread and / or the right-hand thread preferably being multi-start threads. In one embodiment of the invention, the grooves (3) seen in the groove cross-section a rounded bottom and / or rounded edges auf.Die invention further relates to a method and a tool for producing the plain bearing bush.

Description

The invention relates to a plain bearing bush and a method and a tool for producing the plain bearing bush.

Slide bearings, which are often formed from copper-zinc alloys, in particular in applications for construction machines such as wheel loaders, excavators and the like, are well known from the prior art. In particular, the problem is the wear that occurs in the interaction of the sliding bearing with axes mounted therein and reduces the life of the plain bearings.

The invention has for its object to provide a plain bearing bush of the type mentioned, which has a longer life compared to the known plain bearing bushings.

According to the invention the object is achieved in that grooves are arranged on the inner circumferential surface of the plain bearing bush, which together form a grid.

On the one hand, the grooves have the effect of reducing the friction coefficient of the sliding bearing, and on the other hand, a uniform distribution of lubricant between the inner circumferential surface and the axis is promoted. As a result, direct contacts of plain bearing bush and the ache, which can cause a relatively strong closure avoided. In addition, soiling, which can significantly increase the wear, transported out of the area between the inner circumferential surface and the axis when moving the plain bearing bush about the axis.

Advantageously, thereby extending the life of the plain bearing bush.

In one embodiment of the invention, the grooves are formed by means of a machining process, in particular turning or milling. By machining, as compared to groove formation, e.g. By knurling or other forming technology with respect to the inner circumferential surface comply with lower manufacturing tolerances. In addition, embrittlement, which can occur due to the strain hardening or forming occurring during subsequent heat treatment, avoided. The more accurate production results in an extension of the service life of the plain bearing bushings, since a particularly uniform storage of the axle can be achieved.

Moreover, the use of the machining process significantly better ways to form the grooves in relatively small dimensions and small distances from each other and give the grooves forms that improve the distribution of the lubricant or a removal of impurities from the area between the tread and can support the axis.

For producing the grooves, the aforementioned tool according to the invention has proven to be suitable, which is characterized by a cutting means for, preferably machining, processing the inner circumferential surface of the plain bearing bush. The tool enables an economical and production-optimized production of the plain bearing bush.

In one embodiment of the invention, the grooves are formed, preferably by means of turning or milling, as a left-hand thread and as a right-hand thread. Advantageously, the grid, which preferably has a rhombic structure, can be produced in this way with relatively little effort and with basically known and easily controllable thread-forming techniques, e.g. using a CNC lathe, automated manufacture.

Surprisingly, it has been shown that the plain bearings have particularly low coefficients of friction when the grooves have a maximum width of 2 mm, preferably 1.5 mm, and / or a maximum spacing of 3.6 mm, preferably 2.0 mm.

Conveniently, said cutting means is an insert, preferably for use in turning and / or milling, in particular an indexable insert provided with at least one tooth for cutting the groove. The cutting plate can be provided with several, preferably two to four, cut sides and be provided in such a way that the different cut sides, depending on the arrangement, come into engagement with the plain bearing bush in the inner circumferential surface. Advantageously, the cutting plate can still be used when the respective cut side is worn by the cutting plate is rotated so that one of the other cutting sides can edit the inner surface. It is understood that by turning the insert both sides of each cut side can be used to make the grooves.

In a particularly preferred embodiment of the invention, the left-hand thread and / or the right-hand thread are formed as multiple threads. Because several parallel grooves can be made simultaneously in the production of the multi-start thread, the grid can in comparison to the production of a catchy thread in be made much shorter time. This proves to be particularly advantageous if, as explained in more detail below, the grooves are formed in relatively small dimensions and with relatively small distances from each other, since the processing times can be significantly shortened.

The cutting means is expediently provided with at least two, preferably a plurality of teeth for the simultaneous introduction of respectively different ones of the grooves, i. of different courses of the respective multi-thread, provided. It has proved to be particularly advantageous to provide the cutting means with 5 to 10 teeth.

Conveniently, the respective tooth crests of the tooth or teeth are arranged in the tool in the threading direction.

The tool according to the invention expediently comprises at least one cutting means for forming the right-hand thread or, in the case of producing a multi-thread, the right-hand thread and at least one cutting means for forming the left-hand thread or the left-hand thread.

In one development of the invention, the tool comprises a holding device for the cutting means, preferably for use in a lathe or a milling machine.

The cutting means and the holding device are expediently arranged such that the respective cutting means on the inner surface of the plain bearing bush with a clearance angle of 5 to 9 °, preferably 6.5 to 7.5 °, with a rake angle of - 3 to + 3 °, preferably -1 to +1 °, and with a wedge angle of 80 to 85 °, preferably 82 to 84 °, works.

In one embodiment of the invention, the bottom of the groove or the grooves seen in the groove cross section has a rounded shape. Advantageously, the rounded shape of the groove base supports the transport of the lubricant in the groove and thus the uniform distribution in the region between the inner circumferential surface and the axis.

Accordingly, the tips of the tooth or teeth are expediently rounded. Advantageously occurs at the cutting means in comparison to the formation of a bottom having an acute-angled cross-sectional shape, a much lower wear, so that can be achieved for the cutting means significantly longer life.

It has proven expedient to provide the radius of the rounding at the cutting means or at the groove bottom with 0.1 to 0.3 mm, preferably 0.15 to 0.25 mm.

The depth of the grooves on the groove bottom is suitably 0.1 to 0.8 mm, preferably 0.2 to 0.4 mm.

In one embodiment of the invention, the distance between the grooves is at most 3 mm, preferably at most 2 mm.

Conveniently, the flank angle of the grooves is 80 to 100 °, preferably 87 to 93 °.

In a particularly preferred embodiment of the invention, the grooves are provided in the groove cross-section with convexly rounded edges to improve the transport and distribution of the lubricant. It has proved to be particularly advantageous to form the edges in such a way that they transition tangentially into an inner wall region of the inner circumferential surface of the plain bearing bush lying between the grooves, preferably in such a manner that from the groove flank to the inner lateral surface a rounded, kink-free, in particular continuous Smoother, transition is formed. The rounding at the edges expediently have a radius of 1 to 1.5 mm, preferably 1.15 to 1.25 mm.

While it would be conceivable to provide the cutting inserts in such a way that the tooth flanks have a concave shape over the entire length thereof to form the rounding off of the respective groove edges, the tooth flanks are provided with a bulge in one embodiment of the invention. The bulge is expediently shaped such that it can form a rounding at the respective groove edge. It is preferably concave at least on its side of the respective tooth tip, so that it can provide the groove edge with the convex shape when cutting the groove.

The tool is expediently moved in such a way that the teeth penetrate only so deeply into the inner lateral surface of the bushing for insertion of the grooves that the rounding is formed by means of the bulge at the edge of the groove.

Conveniently, plain bearing bush is formed by a one-piece or two-part, preferably closed, hollow cylinder, which preferably has a circular or elliptical shape in cross-section.

In a particularly preferred embodiment of the invention, the plain bearing bush is formed from steel, preferably from one of the steels 20MnV6, 17MnV6, 19MnVS6 or 22MnV6, from a E460 or E470 pipe steels, from one of the bearing steels 100Cr6 or 100 CrMo6 or one of the spring steels C67, C74 or 50CrV4.

In one embodiment of the invention, the plain bearing bush for surface hardening with carbon or with a combination of carbon and nitrogen, optionally with boron, enriched and optionally post-oxidized, preferably by means of a pulse-plasma method at relatively low temperatures of about 500 to 530th ° C, more preferably for more than 10 hours, especially 12 to 14 hours. Advantageously, by this treatment at a relatively low temperature, the delay, which occurs through the hardening and heat treatment, be kept so low that the sliding bearing, even if it has a certain delay, which usually shows in an elliptical rather than round cross-sectional shape, without additional treatment eg used by grinding, i. can be inserted into a suitable holder of a plain bearing.

This advantageously eliminates the additional processing steps normally required to produce plain bearing bushes made of steel, such as regrinding and subsequent treatment to prevent corrosion, i. the application of a phosphate layer or a galvanic layer.

Surprisingly, it has been shown that it is possible by the above-described groove structure on the inner to combine pairings of a plain bearing bush made of steel with a steel shaft with a sufficiently long service life.

Advantageously, it can be avoided to use a copper alloy for the preparation of the plain bearing bushes, by means of which, although comparatively easy to produce exactly cylindrical plain bearing bushes, but on the one hand causes much higher costs and on the other hand compared to steel much lower hardness and therefore a larger Tendency to wear, in particular caused by contamination in the region between the inner circumferential surface and the axis has.

The plain bearing bushing according to the invention has proved to be particularly wear-resistant even in applications in which, for example due to insufficient lubrication, mixed friction can occur. Furthermore, it proves to be particularly resistant to wear in applications in which by means of the sliding bearing bush pivotal movements, but not complete rotations are performed.

In a particularly preferred embodiment of the invention, the plain bearing bushing for use in construction machine joints, for example for the storage of blades of wheel loaders, excavators, mobile cranes or the like is provided. The plain bearing bushing is particularly suitable for loads on which surface pressures in the range of 50 to 150 MPa, being preferably carried out with sliding speeds of 0.5 to 2 m / min.

• 1 eine erfindungsgemäße Gleitlagerbuchse in verschiedenen Ansichten,
• 2 ein Werkzeug zur Herstellung der Gleitlagerbuchse nach 1,
• 3 einen Teil des Werkzeugs nach 2,
• 4 im Querschnitt die innere Mantelfläche der Gleitlagerbuchse nach 1,
• 5 einen Teil eines weiteren erfindungsgemäßen Werkzeugs, und
• 6 im Querschnitt die innere Mantelfläche einer weiteren erfindungsgemäßen Gleitlagerbuchse.

The invention will be explained in more detail below with reference to exemplary embodiments and the accompanying drawings relating to the exemplary embodiments. Show it:

• 1 a plain bearing bush according to the invention in various views,
• 2 a tool for the production of the plain bearing bush 1 .
• 3 a part of the tool 2 .
• 4 in cross section, the inner circumferential surface of the plain bearing bush 1 .
• 5 a part of another tool according to the invention, and
• 6 in cross section, the inner circumferential surface of a further plain bearing bush according to the invention.

In 1a is a perspective view of a plain bearing bush according to the invention 1 represented, which is formed of steel and on its inner circumferential surface 2 through grooves 3 a grid 4 is formed. The grid 4 is enlarged in 1b shown. The grooves 3 are as multi-course left-hand thread 5 as well as multi-course right-hand thread 6 formed with a pitch angle of 46 ° and are on the inner lateral surface 2 in relation to each other provided such that on the inner circumferential surface 2 unprocessed diamond-shaped sections 16 remain.

The plain bearing bush 1 is intended for use in construction machinery, for example for the storage of blades of wheel loaders, excavators, mobile cranes or the like and is adapted to work at surface pressures in the range of 50 to 150 MPa and at sliding speeds of 0.5 to 2 m / min. The plain bearing bush 1 has a coefficient of friction of μ = 0.08 to 0.12. It has an average outer diameter of 50 mm and can, as explained below, due to the production have a cross-sectionally slightly elliptical shape. The elliptical shape is characterized by a deviation from the mean outer diameter of 50 to 250 microns with respect to the large ellipse axis and by a deviation of -30 microns to -160 microns with respect to the small ellipse axis.

In 2 is a turning tool 9 shown for use in a lathe, not shown here, a clamping holder 18 at which a more precise in 3 shown insert 10 is arranged.

The cutting plate 10 has a substantially triangular shape and is on one of its sides of the triangle 11 with ten teeth 12 provided for the formation of the grooves 3 on the inner surface 2 the plain bearing bush 1 are provided. In particular 3 e and d can be seen are tooth tips 13 the teeth 12 rounded.

As the 3a and b show are different inserts for cutting the right-hand thread and for cutting the left-hand thread 10a . 10b provided by aligning their tooth combs 17a . 17b differ from each other. The tooth combs 17a , 17b are according to the thread pitch to be introduced obliquely to the normal on the circular surface of the insert 10a . 10b arranged. It is understood that the different inserts 10a . 10b on different clamp holders 18 can be arranged and possibly together in the lathe, for example on a suitable turret, can be arranged.

Notwithstanding the inserts shown here 10a . 10b The other triangle sides of the cutting plate could also be provided with teeth. Such a cutting board would not be possible only by turning and arrangement on different sides of the holder 18 continue to wear after wear, but also by turning the cutting plate so and on the tool holder 18 would be arranged, that in each case a still unused triangular side in the inner lateral surface 2 can intervene.

Between adjacent tooth flanks 14 the teeth 12 there is an angle of 90 °, the tooth tips 13 are arranged at a distance of 2 mm and have a radius of 0.2 mm.

Will the inner surface area 2 by means of the cutting plate 10 edited so that the teeth 12 only with about half their length in the inner lateral surface 2 penetrate, become grooves 3 with the in 4 produced cross-section shown. The grooves 3 indicate according to the rounded shape of the tooth tips 13 at her bottom 7 also a rounded shape. On the one hand, this form promotes the transport of lubricant on the inner lateral surface 2 during operation of the plain bearing bush 2 for supporting an axle. On the other hand uses the cutting plate 10 in the formation of the grooves 3 compared to teeth with sharp-edged tooth tips significantly less strong, so the life of the insert 10 is much longer in comparison.

It is understood that for the production of the left-hand thread 5 and the right-hand thread 6 different, adapted to the respective cutting direction turning tools 9 to be provided. Apart from different clamp holders 18 for holding the inserts 10 must be provided in the respective cutting direction, also the tooth combs 17 the teeth 12 be aligned according to the respective cutting direction.

Will the appropriate tool for the cutting direction 9 equipped with the cutting plate 10a or 10b arranged in a suitable lathe and a plain bearing bush 1 provided in the lathe for machining, the grooves 3 on the inner surface 2 initially as a multi-course left-hand thread 5 or as a right-hand thread 6 brought in. Provided that the entire inner circumferential surface 2 with a single twisting motion over its entire inner circumference with the grooves 3 provided can be provided to perform several cutting movements in succession. Then the grooves 3 in the reverse direction, ie as a right-hand thread 6 or left-hand thread 5 in the inner lateral surface 2 turned to the grid 4 to create.

Advantageously, the grid 4 by the use of the cutting plate according to the invention 10a . 10b be generated in a much shorter time than when creating each groove 3 individually. In addition, the service life of the insert is extended 10a . 10b by the simultaneous processing with the different teeth 12 Significant compared to a cutting insert with a single tooth.

In 5 are further inserts according to the invention 10c . 10d shown by those after 3 this distinguishes that on their tooth flanks 14c of teeth 12c bulges 15 are formed in the area between rounded tooth tips 13 have a concave shape. The bulges 15 are provided in the concave shape to edges 8th of grooves 3c , which means using the teeth 12c on an inner lateral surface 2c a plain bearing bush 1c make it possible to round off. A corresponding rounded shape of the edges 8th is in 6 shown. The rounded edges 8th have a positive effect on the lubrication of the plain bearing bush 1c because they promote the transport of lubricant.

When processing the inner lateral surface 2c become the teeth 12c , 12d on the insert 10c . 10d just as deep into the inner surface 2c Inserted that the lower ends of the bulges 15 when cutting exactly at the height of the surface of the inner surface 2c are arranged. This will make a steady transition from the groove edge 8th to the inner surface 2c created.

After the introduction of the grooves 3 , 3c is the plain bearing bushing 1 , 1c for surface hardening with carbon or with a combination of carbon and nitrogen, optionally with boron, enriched and possibly post-oxidized. For this purpose, a pulse plasma method is carried out at 510 ° C for 12 hours. Due to this treatment, a certain delay arises in the slide bearing bushing, which in the elliptical shape of the plain bearing bush described above 1 , 1c results. The plain bearing bush thus formed 1 , 1c can be used with proper handling without further post-processing directly intended, ie insert into a suitable holder of a sliding bearing.

Claims (15)

Sliding bearing bush, characterized by grooves (3) which are arranged on the inner circumferential surface (2) of the plain bearing bush (1) and together form a grid (4). Plain bearing bush to Claim 1 , characterized in that the grooves (3) form a left-hand thread (5) and a right-hand thread (6), wherein the left-hand thread (5) and / or the right-hand thread (6) are preferably multi-start threads. Plain bearing bush to Claim 1 or 2 , characterized in that the grooves (3) seen in the groove cross section have a rounded bottom (7) and / or rounded edges (8). Plain bearing bush according to one of Claims 1 to 3 , characterized in that the distance of the grooves (3) from each other at most 3 mm, preferably at most 2 mm. Plain bearing bush according to one of Claims 1 to 4 , characterized in that the plain bearing bush (1) by a one-piece or two-piece, preferably closed, hollow cylinder is formed, which preferably has a circular or elliptical in cross-section shape. Plain bearing bush according to one of Claims 1 to 5 , characterized in that the bearing bushing (1) is formed of steel, preferably one of the steels 20MnV6, 17MnV6, 19MnVS6 or 22MnV6, one of the E460 or E470 tube steels, one of the 100Cr6 or 100 CrMo6 bearing steels or one of the C67 spring steels , C74 or 50CrV4. Method for producing a plain bearing bush (1), characterized in that grooves (3) are formed on the inner circumferential surface (2) of the plain bearing bush (1) in such a way that together they form a grid (4), Method according to Claim 7 , characterized in that to form the grooves (3), preferably by means of a machining process, a left-hand thread (5) and a right-hand thread (6) is formed, wherein the left-hand thread (5) and / or the right-hand thread (6) preferably as mehrgängige Thread are formed, particularly preferably by means of the tool (9) according to one of Claims 12 to 15 , Method according to Claim 7 or 8th , characterized in that the grooves (3) to improve the lubrication of the plain bearing bush (1) are provided with a rounded in cross section bottom (7) and / or seen in cross section rounded edges (8). Method according to one of Claims 7 to 9 , characterized in that the plain bearing bush (1) for surface hardening with carbon or with a combination of carbon and nitrogen, optionally additionally enriched with boron, and preferably post-oxidized, more preferably by means of a pulse-plasma method at relatively low temperatures of about 500 to 530 ° C, wherein the plain bearing bush (1) after the surface hardening preferably without additional post-processing for the intended use, in particular for joining in a suitable holder of a sliding bearing, is provided. Tool (9) for producing a plain bearing bush (1) by a cutting means (10a, 10b, 10c, 10d) for processing the inner circumferential surface (2) of the plain bearing bush (1), by means of which at least one groove (3) for forming of a grid, characterized in that the cutting means (10a, 10b, 10c, 10d) is an insert, preferably for use during turning and / or milling, in particular a turning plate, which is provided with at least one tooth (12). for cutting the groove (3) is provided. Tool after Claim 11 , characterized in that the cutting means (10a, 10b, 10c, 10d) with at least two, preferably a plurality of teeth (12) for simultaneously introducing in each case different of the grooves (3), in particular a multi-course left-hand thread or a multi-threaded right-hand thread is provided. Tool after one of Claims 10 to 12 , characterized in that the tip (13) of the tooth or the tips (13) of the teeth (12) is rounded or are. Tool after Claim 12 or 13 , characterized in that the flanks (14) of the teeth (12) at least partially have a concave shape, wherein the flanks (14) preferably with a bulge (15) is provided, which is intended to form a rounded at the respective groove edge (16), wherein the bulge (15) is preferably concave on its side facing the respective tooth tip (13) to the groove edge ( 16) to be provided with a convex shape. Tool after one of Claims 10 to 14 , characterized in that the tool (9) comprises a holding device (18), preferably a lathe (19), and the cutting means (10) and the holding device (18) are provided such that the cutting means (10) on the inner circumferential surface (2) the plain bearing bush (1) with a clearance angle of 5 to 9 °, preferably 6.5 to 7.5 °, a rake angle of - 3 to + 3 °, preferably -1 to +1 °, and a wedge angle of 80 to 85 °, preferably 82 to 84 ° works.

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