EP4735770A1

EP4735770A1 - Bearing of a conveyor and conveyor with such a bearing

Info

Publication number: EP4735770A1
Application number: EP23748518.0A
Authority: EP
Inventors: Recep UZUN; Bo Niclas Thim
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2023-06-27
Filing date: 2023-07-27
Publication date: 2026-05-06
Also published as: DE102023206012A1; WO2025002586A1; CN121443855A

Abstract

Bearing (10) of a conveyor with at least an outer ring (12), at least an inner ring (14), rolling elements (16), which are designed to roll on the outer ring and the inner ring, and grease for lubricating movements of the rolling elements relative to the outer ring and the inner ring, wherein the grease contains Molybdenum disulfide.

Description

BEARING OF A CONVEYOR AND CONVEYOR WITH SUCH A BEARING

The invention concerns a bearing of a conveyor and a conveyor.

It is known to use spherical roller bearings to support a belt of a conveyor in a movable way. Examples for such bearings are the bearings 22205 E and 22206 E (cf. the SKF general catalog of 2018, page 792). The bearings don't comprise any seals. In the arrangement in the conveyor the bearings are sealed with external seals.

The problem of the invention is in particular to provide a bearing of a conveyor which has a high degree of efficiency. The problem is solved according to the invention by the features of claim 1 and by the features of claim 10, while advantageous embodiments and further embodiments of the invention can be taken from the subclaims.

The invention proceeds from a bearing of a conveyor with at least an outer ring, at least an inner ring, rolling elements, which are designed to roll on the outer ring and the inner ring, and grease for lubricating movements of the rolling elements relative to the outer ring and the inner ring.

It is proposed that the grease contains Molybdenum disulfide. Through this a bearing of a conveyor, which has a high degree of efficiency, can be provided. In particular, a long lifetime of the grease can be achieved. In particular, during start stop operations of the conveyor a lubricant film is secured but molybdenum disulfide, which prevents metal to metal contact and decreases the creation of harmful wear particles. In particular, with the help of the Molybdenum disulfide a lubrication which is unaffected by dilute acids and oxygen can be reached.

With advantage the sum of the masses of Molybdenum and Molybdenum ions in the Molybdenum disulfide contained in the grease deviates from 6900 pg per gram of the grease at most by 2900 pg per gram of the grease, preferably at most by 1200 pg per gram of the grease and most preferably at most by 400 pg per gram of the grease. Thereby an efficient lubrication and a long lifetime of the grease and the bearing can be achieved, in particular despite of frequent start stop operations of the conveyor.

In particular, the grease can contain between 0.6 mass percent and 2.5 mass percent Molybdenum disulfide. Moreover, it is suggested that one row of the rolling elements of the bearing contains less than 1 .05 rolling elements per centimeter of the pitch circle perimeter of the row and more preferably less than 0.879 rolling elements per centimeter of the pitch circle perimeter of the row. Through this energy can be saved during the operation of the conveyor without diminishing the lifetime of the bearing in the conveyor. Moreover, costs can be saved.

Advantageously the bearing is a spherical roller bearing, which lacks a guide ring. Through this unnecessary friction can be avoided, which means that energy can be saved during operation.

Furthermore, it is proposed that at least one cage of the bearing is hardened. Thereby a long lifetime of the bearing can be achieved through avoiding premature failure of the cage, in particular through hammering forces exerted by the rolling elements coming from frequent start stop operations of the conveyor. In particular, the cage can be nitrile hardened. In particular, two cages of the bearing can be hardened, in particular nitrile hardened.

In particular, the bearing can be a spherical roller bearing.

Moreover, it is suggested that the bearing comprises a cage, which comprises on an axially outer face side a first surface area, which is located at a radially inner end of the face side and which has a smaller axial distance from a center of mass of the cage than a second surface area of the face side. Through this a contact between the cage and a sealing of the bearing during operation can be avoided, which implies that energy can be saved. In particular, the first surface area can be ring shaped.

With advantage a maximum radial load of the bearing during operation is 6580 Newton and/or a maximum axial load of the bearing during operation is 566 Newton. Through this a low mass of the bearing can be reached.

Advantageously, the grease contains graphite. Thereby improved lubrication can be achieved in case an oil film breaks down. In particular, the grease can contain between 0.6 mass percent and 2.5 mass percent graphite.

In particular, a first seal is fixed to the outer ring or the inner ring in order to seal a space between the inner ring and the outer ring. In particular, a second seal is fixed to the outer ring or the inner ring in order to seal a space between the inner ring and the outer ring. Furthermore, it is suggested that a base oil of the grease is mineral oil and/or a thickener of the grease is lithium and/or calcium. Through this a high oxidation stability and a long lifetime of the grease can be reached.

Moreover, it is proposed that one row of the rolling elements of the bearing contains between 67% and 87%, preferably between 72% and 82%, of the number of such rolling elements which the row can maximally contain. Thereby the bearing can take a sufficient amount of load with little weight and a low energy consumption during operation. In particular, all the rolling elements are identical in construction. In particular, a further row of the rolling elements of the bearing contains between 67% and 87%, preferably between 72% and 82%, of the number of such rolling elements which the further row can maximally contain.

Furthermore, a conveyor with a bearing as described in the preceding text his proposed, wherein the bearing supports a roll of the conveyor rotatably, wherein the roll supports a belt of the conveyor in a moveable way. Thereby a conveyor and a bearing of a conveyor which have a high degree of efficiency can be achieved. In particular, the roll can transfer a drive to the belt.

Further advantages can be seen in the following description of the drawings. Examples of embodiments of the invention are shown in the drawings. The drawings, the description and the claims contain numerous features in combination. The skilled person will expediently also consider the features individually and combine them to form useful further combinations.

Fig. 1 shows a half section through a bearing of a conveyor according to the invention,

Fig. 2 shows a half section through an alternative embodiment of a cage of a bearing according to the invention,

Fig. 3 shows a half section through an alternative embodiment of a bearing of a conveyor according to the invention, and

Fig. 4 shows a part of a conveyor with a bearing according to the invention.

Figure 1 shows a half section through a bearing 10 of a conveyor according to the invention. The bearing is a spherical roller bearing. It comprises an outer ring 12, an inner ring 14 and rolling elements 16 which are designed to roll on the outer ring and the inner ring. The bearing comprises grease (not shown) for lubricating movements of the rolling elements relative to the outer ring and the inner ring. A space 36 between the inner ring and the outer ring is sealed by a first seal 38 and a second seal 40. The first seal is fixed to the outer ring in a form locking way and is located at a first axial end of the bearing. The second seal is also fixed to the outer ring in a form locking way and is located at a second axial end of the bearing. The first seal consists of a metal part and a part made from nitrile butadiene rubber. The second seal is identical in construction with the first seal. Between 35 % and 45% of the part of the space 36 which is free is filled with the grease. The bearing contains a first row 18 of the rolling elements and a second row 19 of the rolling elements.

The grease contains between 0.6 mass percent and 2.5 mass percent molybdenum disulfide. The sum of the masses of Molybdenum and Molybdenum ions in the Molybdenum disulfide contained in the grease deviates from 6900 pg per gram of the grease at most by 2900 pg per gram of the grease. Preferably the sum of the masses of Molybdenum and Molybdenum ions in the Molybdenum disulfide contained in the grease deviates from 6900 pg per gram of the grease at most by 400 pg per gram of the grease. The grease also contains between 0.6 mass percent and 2.5 mass percent graphite.

Moreover, the grease contains 2450 mg/kg Lithium, 1200 mg/kg Phosphorus, 5400 mg/kg Zinc, 2900 mg/kg Calcium, less than 2 mg/kg Barium and 20 mg/kg Magnesium. These values can deviate up to 30% and preferably up to 15%.

The operating temperature range of the grease is -20 to 120°C. The base oil viscosity of the grease is 500mm²/s at 40°C and 32 mm²/s at 100°C.

The content and the properties of the grease have been found out to be very advantageous in extensive research.

Both rows 18, 19 of the rolling elements 16 of the bearing contain less than 1.05 rolling elements per centimeter of the pitch circle perimeter of the row. The bearing also lacks a guide ring.

A cage 20 and a cage 21 keep the rolling elements on a distance from each other. The cage bars are located in the pitch circle area. Both cages are nitrile hardened. The cages are pressed steel sheet metal cages.

A maximum radial load of the bearing during operation is 6580 Newton and a maximum axial load of the bearing during operation is 566 Newton. A base oil of the grease is mineral oil and a thickener of the grease is lithium and calcium. The base oil is circa 79 weight percent of the Grease. The NLGI consistency class of the grease is 2 or 3. The grease is a high viscosity grease with high oxidation stability. Molybdenum disulfide is used as a dry lubricant because of its low friction and robustness.

Figure 4 shows a section through a part of a conveyor with the bearing 10. The bearing 10 and a further bearing 11 supports a roll 32 of the conveyor rotatably. The further bearing 11 is identical in construction with the bearing 10. The roll supports a belt 34 of the conveyor in a moveable way. With the help of the belt the conveyor can transport for example parcels which are sent by mail. A top part of the belt performs a translational motion in order to transport objects (for example parcels). The roll can transfer a drive to the belt in order to cause the motion of the belt.

A limiting speed of the inner ring rotation is 1800 rounds per minute. A limiting speed of the outer ring rotation is 1400 rounds per minute. The pitch circle diameters of each of the rows are the same. They are 39.5 millimeters. The size of the rolling elements is 7.13 millimeters times 6.6 millimeters, wherein the 7.13 millimeters are a maximum diameter of the rolling elements. Each row has 13 rollers. A radial clearance of the bearing is between 0.025 millimeters and 0.04 millimeters. Coming from said diameter of the rollers and said pitch circle diameter, a full complement set of rollers would comprise 17 rollers. So, the selected 13 rollers correspond to a filling degree of 76 % of the full complement.

The selected combination of features of the bearing enables an optimized balance between bearing life, operational performance and costs under the conditions of this specific application resulting from extensive calculations and tests.

Figure 2 shows an alternative embodiment of a cage 20a of the bearing 10. A side ring 42a has an extension 44a which extends radially inwardly. The cage 20a comprises on an axially outer face side 22a a first surface area 24a, which is located at a radially inner end 30a of the face side and which has a smaller axial distance from a center of mass 26a of the cage than a second surface area 28a of the face side. In a state in which the cage 20a is assembled into the bearing 10 the face side faces the seal 38. The location of the first surface area 24a provides additional misalignment capabilities to the bearing and disables the cage to interfere with the seal 38 during misalignment of the bearing. With the help of the first surface area 24a up to 1 degree of misalignment for the bearing is secured. Figure 3 shows a half section through a further embodiment of a bearing 10b according to the invention. The only differences in comparison with the bearing 10 are the following: The sealing lips of the seals are bigger in relation to the bearing rings. The limiting speed of the inner ring rotation is 1500 rounds per minute. A limiting speed of the outer ring rotation is 1200 rounds per minute. A pitched circle diameter of the rows is 47.1 millimeters. The size of the rolling elements is 8.45 millimeters times 7.4 millimeters, wherein the 8.45 millimeters are a maximum diameter of the rolling elements. A maximal radial load of the bearing during operation is 6580 N. The cage of figure 2 can also be used for the bearing 10b (then only with adapted dimensions).

List of reference numerals:

Claims

Claims:

1 . Bearing (10) of a conveyor with at least an outer ring (12), at least an inner ring (14), rolling elements (16), which are designed to roll on the outer ring and the inner ring, and grease for lubricating movements of the rolling elements relative to the outer ring and the inner ring, characterized in that the grease contains Molybdenum disulfide.

2. Bearing (10) of a conveyor according to claim 1 , characterized in that the sum of the masses of Molybdenum and Molybdenum ions in the Molybdenum disulfide contained in the grease deviates from 6900 g per gram of the grease at most by 2900 pg per gram of the grease.

3. Bearing (10) of a conveyor according to claim 1 or claim 2, characterized in that one row (18) of the rolling elements (16) of the bearing contains less than 1 .05 rolling elements per centimeter of the pitch circle perimeter of the row.

4. Bearing (10) of a conveyor according to at least one of the preceding claims, characterized in that the bearing is a spherical roller bearing, which lacks a guide ring.

5. Bearing (10) of a conveyor according to at least one of the preceding claims, characterized in that at least one cage (20) of the bearing is hardened.

6. Bearing (10) of a conveyor according to at least one of the preceding claims, characterized by a cage (20a), which comprises on an axially outer face side (22a) a first surface area (24a), which is located at a radially inner end (30a) of the face side and which has a smaller axial distance from a center of mass (26) of the cage than a second surface area (28a) of the face side.

7. Bearing (10) of a conveyor according to at least one of the preceding claims, characterized in that a maximum radial load of the bearing during operation is 6580 Newton and/or a maximum axial load of the bearing during operation is 566 Newton.

8. Bearing (10) of a conveyor according to at least one of the preceding claims, characterized in that the grease contains graphite.

9. Bearing (10) of a conveyor according to at least one of the preceding claims, characterized in that one row (18) of the rolling elements (16) of the bearing contains between 67% and 87% of the number of such rolling elements which the row can maximally contain.

10. Conveyor with a bearing (10) according to at least one of the preceding claims characterized in that the bearing supports a roll (32) of the conveyor rotatably, wherein the roll supports a belt (34) of the conveyor in a moveable way.