FI79747B - LAGERENHET. - Google Patents

Description

79747 1989-06-29 FI 1167

BEARING UNIT - BEARINGS

The invention relates to a bearing unit according to the preamble of claim 1.

In a conventional bearing, there is a problem of wear of the bearing or the bearing-5 rotatable member at the point of contact where the load and movement differences between them are large. Known solutions have been able to avoid these disadvantages by means of lubrication of the contact area, selection of materials, treatment of the contact surface of the rotatable member or interchangeable wear parts. Some examples are described below:

The long-known fluid or pneumatic lubrication prevents direct contact between the rotatable member and the bearing in the contact area. Lubrication also eliminates the effect of wearable particles quite well. However, known problems include high operating temperatures or the presence of corrosive substances in the bearing environment that can damage the bearing despite lubrication.

The bearing shaft is often a precisely dimensioned, 20-intensive and expensive body. In a known solution, the wear is applied to the bearing, whereby the contact surface of the bearing is softer than the contact surface of the shaft. The worn bearing is replaced by a new bearing, which is fitted between the shaft and the frame member. The disadvantage is that in this case the relatively large amount of work required for a precise fit of the bearing, which slows down the replacement. An additional disadvantage is the dimensional accuracy of the bearing required for precise fitting, which is why an accurately dimensioned bearing part must be readily available when stored, which increases the amount of unproductive capital.

30 The durability of contact surfaces can be extended by curing them, for example by utilizing nitration, boring or other curing methods. However, the procedure increases manufacturing costs to 2 79747. However, even this arrangement does not eliminate the wear problem.

It is also known to arrange the sleeve between the rotating shaft and the actual bearing. In known solutions, the sleeve 5 can be frictionally attached to the shaft (rolling bearings) or the sleeve rotates relative to the shaft (plain bearings). In the latter case, the contact surface of the shaft must be made harder than the corresponding surface of the sleeve. If the sleeve is made of soft material, it often needs to be replaced due to wear and tear, 10 causing downtime. If, on the other hand, the sleeve is of the order of the shaft contact surface, there is significant wear on the shaft.

The object of the invention is to provide a bearing unit which avoids the wear of the rotatable element and the support 15 of which, i.e. the permanent attachment to the frame member, can be easily implemented. It is a further object to provide a bearing unit in which any worn parts can be replaced by simple and easily machinable bearing members so that the rotatable element and / or the bearing member in contact with the body member 20 need not be machined.

It is a further object of the invention to provide such a construction in which the same rotatable element can be mounted on an arbitrarily selected support member by treating an easily machinable replacement bearing member. It is also an object 25 to provide a structure in which, for example, shafts of different diameters can be mounted on the same support member by utilizing said bearing element feature.

The object of the invention is achieved by a bearing unit as claimed in claim 1. The first bearing member 30 of the bearing unit is statically supported or fixed relative to the body member and the second bearing member is in static contact with the rotatable member. In a preferred embodiment, the first member is permanently attached to the body member. The same bearing member can then be used in the desired manner 35 with a second bearing member 3 79747 selected from a large number to form a bearing unit. In this case, only the second bearing member needs to be stored in optional sizes, which reduces storage costs. The most important feature of the invention relates to the realization that the main wear part 5 of the bearing unit is directed to the member which can be easily replaced with a new one. This is achieved by arranging the hardness values and resistance to mechanical wear of the first and second bearing members so that the first member is harder and more durable than the second member 10 in the contact area between the members.

In the prior art, the difference in hardness between the bearing and the shaft is used to achieve the effect that an element with a softer hardness tends to bury the foreign particles trapped between the elements. Another realization of the invention is that a more efficient effect than burial is achieved by crushing the foreign particles between the bearing elements. This effect can be further enhanced by removing the crushed material from the bearing. This second finding is illustrated in claims 2 20 and 3, wherein the bearing member, which is weaker against mechanical wear and has a softer hardness, is made of metal or a metal alloy, preferably steel, the wear-prone surface of which is hardened or nitrated, boron or similarly hardened. However, the "softer / worn" bearing member according to the invention is so hard and wear-resistant that foreign particles such as sand-short particles and similar workshop environment particles and metal chips are crushed between the bearing lines without being buried in the second bearing member. However, while maintaining the difference in hardness and wear resistance between the first and second bearing members, the wear caused by rotational motion and foreign particles in long-term use is naturally applied to the second bearing member.

Due to the static contact 35 of the rotatable member and the second bearing member, an additional advantage is achieved. Since these members do not move or rotate relative to each other, the second bearing member does not wear the rotatable member. In this case, for example, no very high demands are placed on the material of the rotating shaft of the rotating shaft. The shaft material can be steel, stone, rubber, structural ceramics, etc.

Due to its properties, the second bearing member is easily machined. It can thus be easily adapted to different sized, rotatable members and machined to fit the first bearing member. In a simple and preferred embodiment of the invention, the second description of the invention described above is utilized. In this case, the bearing unit 10 is a plain bearing, in which the first bearing member is annular and the second bearing member is a correspondingly dimensioned sleeve-like member, which is a metal or a metal alloy. The sleeve member is, for example, by frictional attachment, form mounting or the like in static contact with the end of the rotatable shaft or the shaft spindle.

According to the second finding previously described, the service life of a steel sleeve member is extended, for example, by hardening its contact area surface by hardening, nitration, boron or the like. Even the hardeners-20 are softer than the surface of the first bearing member.

Significant manufacturing technical and economic advantages can be achieved if the first bearing member can be manufactured in a manner other than using normal metal processing techniques (casting, machining, etc.). The first bearing member may comprise a pretreated element made of at least one ceramic preform made by sintering. Such a bearing member is inexpensive and easy to manufacture. It is known per se that 30 several structural ceramic materials are hard and are much more resistant to abrasion than metal types. The technology known in the field of long-life bearing units is based on the use of equally durable bearing members. For example, both bearing members are made of the same ceramic material or both members are made of wear-resistant steel. In non-lubricated bearings, the consumption of 5,79747 is applied to both bearing members, thus partially losing the benefit of durability, as there is a need for renewal for both members. In addition, in the steel construction version, the risk of entrapment is high both in the non-lubricated bearing and in the boundary lubrication conditions (incomplete lubricant film). These features reduce the service life of the bearing unit or limit its use in hard-to-lubricate bearings, even in the event that the need for replacement should not occur due to actual wear.

In this connection, a third, surprising realization of the invention arose: the wear is applied, for example, to a steel, second bearing member, so that a more durable first bearing member is constantly working to work the surface of the first member 15. Thus, in a ceramic / steel combination, the risk of entrapment should not be very significant, at least under normal bearing conditions. In the tests performed, it was found that both said risk of entrapment and also the total wear of the ceramic / steel bearing combination 20 were considerably lower than those of bearings whose first and second bearing members are of the same material. In addition, the total wear of the ceramic / steel combination measured in the experiments could be reduced when the surface 25 of the ceramic bearing member was smoothed into a uniform contact element, which is known to be easily implemented for ceramic products.

This contact element of the first bearing member may be uniform in the contact area, for example an annular, cylindrical or similar element with a smooth surface. Similarly, there may be a plurality of contact elements 30 such that together they form a substantially annular or cylindrical contact surface that functionally corresponds to a smooth surface. By this is meant that the gap, seam or similar boundary member between the different elements is seamlessly connected to the adjacent elements 35. The fluidity can be realized in several different ways known per se, for example by rounding the edge edges of the contact elements, filling the boundary element 6 79747 with a soft filling compound, etc.

The service life of the bearing unit is increased by a lubrication arrangement of the contact area, which uses a liquid, solid or pneumatic lubricating material known per se. In this case, the integral second sleeve member 5 may have a lubrication channel which communicates with the contact area so that the channel extends in the direction of rotation over the entire length of the contact area.

In one embodiment, the ceramic first bearing member is permanently attached to the body member and the surface hardened second sleeve bearing member is releasably supported on the shaft. In this case, the dimensions of the contact area can be adjusted by selecting the dimensioning of the second bearing member. For example, if the implementation involves a long-lasting, heavily loaded bearing, the contact area is wide and lubricated. If a sensitive, lightly loaded bearing is desired, the contact surface of the sleeve member in the contact area is made considerably smaller than the surface of the first member.

The invention will now be described with reference to the accompanying drawing, in which Figure 1 shows a side view and a partial section of an embodiment of the invention, Figures 2 to 4 show some modifications of the embodiment of Figure 1 and Figures 5 and 6 show a detail of Figures 1 to 4. .

The shaft or roller 11 is rotatably supported on the frame 3 by means of a plain bearing. A sleeve 2 of metal or metal alloy is arranged on the spindle 4 of the shaft 11. A ceramic bearing seat 1 is permanently supported or fixed to the body 3, which at least in the bearing contact area 5 is harder than the surface of the sleeve 2 in this area 5. The material and manufacture of the bearing seat 1 are adapted so that the seat 1 is more wear-resistant than the sleeve 2. With this arrangement, wear is applied to the sleeve 2, which 35 can be easily replaced with a new one.

7 79747

The sleeve 2 is made of a hard or hardened material. In one embodiment, the seat 1 and the sleeve 2 made of steel are durable in the region 5 so that any foreign particles that have entered here are ground between the members. In this case, a phenomenon such as particle burial in a bronze sleeve is avoided.

Fig. 1 shows for reference the axial support 10 of the seat 1. Reference numerals 7 and 8 denote the axial dimension of the seat 1 and the sleeve 2 in the area 5. A lubrication arrangement 6 is implemented in connection with the seat of the sleeves 2 and 10, in which a lubricating medium, e.g. air, etc. to the contact area 5.

The modification shown in Figure 2 comprises a steel sleeve 2, the axial dimension 9 of which in the region 5 is considerably smaller than the dimension of the seat 1. This transformation applies to objects where the bearing must be sensitive and precisely aligned to the desired location. In this embodiment, the lubrication arrangement 6 according to Fig. 1 can also direct the lubricant-20 to the area 12. Also in the area 12 a suitable radial dimension of the sleeve 2 and the seat 1 can be selected, for example to implement a narrow contact area.

From the range of prefabricated sleeves, a sleeve can be selected which, as such or machined for a special purpose (e.g. Fig. 25 2), can be used in connection with the seat 1.

The benefits of sleeve machinability are illustrated in Figures 2-4. Area 13 describes the free dimension of the opening between the mandrel 4 and the seat 1 and area 14 the largest possible radial dimension of the seat 1.

The maximum possibility of increasing the radial dimension of the sleeve 2 is indicated by reference numeral 16 and the radial dimension of the seat 1 from the body 3 to the sleeve 2 by reference numeral 15. By machining the prefabricated sleeve 2, spindles 4 with different diameters can be fitted in the same receiving opening (Figs. 2,3).

Claims (8)

8,79747 After a slight machining of the sleeve 2, the shaft 11 can be mounted on a second frame 3 ', where the dimension 15' of the seat 1 is different (Figs. 3,4). At the same time, the axial bearing properties in the region 12 can be changed as shown in Figures 1-4. The contact area 5 can also be changed, for example by shaping the central area K, if it is desired to make the initially uniform area 5 (Fig. 1) more sensitive (Figs. 2-4). Figure 5 shows an axially integral, 10 annular seat 1 with a chamfer 6 'for the channel 6. The receiving opening is indicated by reference A. Figure 6 shows a ring socket formed of ceramic parts a. A bearing unit for rotatably supporting a rotatable member, such as a shaft (11) or the like, on a body member (3) to which the bearing unit is in static contact, the bearing unit being formed of a first very hard bearing member (1) statically supported or attached to the body member (3) and a separate a second bearing member (2) arranged in static contact with the member (4), characterized in that the first (1) and second (2) bearing members form a plain bearing unit in which the second bearing member (2) is a metal or metal alloy, and the second bearing member (2) 2) at least its surface is hardened against wear in the contact area between the bearing members 5 (1,2) and that in the contact area (5,12) between the first and second bearing members (1,2) the hardness and resistance to mechanical wear of the first bearing member (1) are (2) greater than the corresponding characteristics. 1. The parts a are shaped in such a way that the boundary areas 1a and the chamfers 6a between them form smooth transition points 15 so that the seat 6 has a substantially uniform surface shape. The invention is not limited to the embodiments shown, but several variations thereof can be implemented within the scope of the appended claims. For example, the shaft 11 may be a vertically oriented rotatable shaft. In this case, of course, the functional significance of the contact areas 5 and 12 changes and the axial support 10 is increased. Depending on the desired effect, members corresponding to reference numerals K, 13-16 can then be used for both axial and radial support. Bearing unit according to claim 1, characterized in that the surface of the second bearing element (2) in said contact area (5, 12) is made of steel and is hardened in a manner known per se, for example by hardening, nitration, boration or the like. Bearing unit according to one of Claims 1 to 2, characterized in that the first bearing element (1) comprises, by sintering, a pretreated element made of ceramic material with a smooth surface which forms a contact element of the first bearing element. Bearing unit according to Claim 3, characterized in that the contact element of the first bearing element (1) is uniform over the entire contact area. Bearing unit according to Claim 3, characterized in that the first bearing element has a plurality of contact elements (a) which together form a substantially uniform contact surface. Bearing unit according to one of Claims 1 to 5, characterized in that a lubrication arrangement (6) is provided in the contact area using a liquid, solid or gaseous lubricant known per se. Bearing unit according to Claim 6, characterized in that the second bearing element (2) has a lubrication channel (6) which communicates with the contact area (5) over the entire length of the contact area 10 79747 in the direction of rotation. Bearing unit according to one of Claims 1 to 7, characterized in that the first bearing element (1) is permanently attached to the frame member (3) and the second bearing element (2) is releasably supported on the shaft (4) so that the contact area (5, 12) ) dimension can be adjusted by dimensioning the second bearing member (2).