RS52005B - Shaft seal - Google Patents

Abstract

A shaft seal comprises an inner seal (6) at the shaft (2) comprising at least one ring (7,9,11) and a radial external seal at a roller body (1) comprising at least one ring (14,15,16) parallel to an inner ring. There is a projection (17,18,19) from at least one ring that contacts a ring of the other sealing element and wears at the beginning of rotation to produce a small ring gap between the projection and the other ring. An independent claim is also included for a roller for a conveyer, especially a belt or strip conveyer, comprising the above.

Description

DESCRIPTION OF THE INVENTION

The invention relates to a shaft seal with one inner sealing element placed on the shaft, which has at least one ring, and also with one outer sealing element placed on the rolling body, which also has at least one ring, which is generally set parallel to at least one ring of the inner sealing element.

The invention further relates to a roller for conveyors, in particular for a conveyor with a moving belt or belt, with one hollow cylindrical rolling body and one shaft which is supported by at least two bearings, wherein shaft seals are placed next to the bearings.

The invention relates to the technical field of transport devices, and in particular belongs to the elements for transport devices with a moving belt and is registered with MKP marks F16C 13/02(<200601>) or Fl6 J 15/447(2006<01>).

Such pulleys for conveyors, which are provided with at least two suitable shaft seals, are already sufficiently known, for example, from American patent document US 6,287,014. Shaft seals of a similar type, whose inner and outer sealing elements do not touch each other, are generally made with labyrinth type seals. In principle, the sealing action will be produced between a single rotating shaft installed in the housing by means of conveniently spaced rings on the shaft, which move in corresponding grooves on the non-porous static housing. Here, the sealing path - the surface will be extended several times. By extending the sealing path, the sealing pressure is significantly reduced due to the presence of friction that is created on the sealing medium, which is on the sealing path - the surfaces, which must (pressure) be so great, to be maintained at the end of the sealing path so that there is no difference or almost no difference in pressure compared to the pressure outside the shaft seal.

The sealing path has several chambers placed alternately towards each other, which are connected to each other via a labyrinth slot, thus building places for damping. There, in the labyrinth slot, the pressure energy is partly converted into kinetic energy, and in the next chamber, the pressure energy decreases, because there the energy is partly spent on creating a vortex flow, partly turns into heat, and this leads to a loss of pressure energy. By continuing the series of back-to-back chambers and labyrinth slots, the high pressure level for the shaft seal is lost through it and drops to a low pressure level.

Due to the high hydraulic resistance in the long labyrinth gaps - slots, only a small - tolerable amount of gas or liquid can escape and leak through the labyrinth seal outside the seal. It is not possible to achieve absolutely complete sealing with this construction of the seal. The amount of liquid that flows out can be further reduced by reducing the width of the labyrinth or sealing slits.

Laviline, i.e. sealing gaps - slits usually have their smallest width between the front surface of the ring and the groove. A sealing effect may also be possible. The amount of liquid that flows out can be further reduced by reducing the width of the labyrinth or sealing slits.

Labyrinth, i.e. sealing gaps - slits usually have their smallest width between the front surface of the ring and the groove. The effect of the seal can also be improved, as it is given in the example from the patent document DE 20163734, where the following characteristics are obtained also through the small measure of the axial slot between the ring and the groove: the mentioned increase in the pressure of the shaft seal is manifested, where the side surface of the ring and the surface of the groove in the derived state are in contact with each other and thus at the moment of movement, they rub against each other, so that the minimum size of the slot is reached. In the case when the shaft is at rest and the body of the pulley rotates around it, this leads to the fact that the load on the pulleys from the transported material produces deformation of the pulleys and loss of geometry, and also leads to the disruption of the shaft seal. With the load lying down and with a force acting vertically downwards, for example in the case of the gravity of the transported load on the conveyor belt, it will happen that the outer sealing element bends - tilts above the axis of the reel in the direction of the inner sealing element. Below the reel shaft, the outer sealing element will separate from the inner one due to the inclination of the inner sealing element. From there, it results that the sealing elements above the reel shaft come into contact and rub against each other, that is, friction occurs, and at the same time, the size of the gap - slot - will increase under the reel shaft.

This leads to a pumping effect (pump effect) during the rotation of the reel, so that moist air and/or dust can be drawn through the outer labyrinth slot into the path - the sealing surface. By changing the size of the slot in the direction of reducing the gap and especially creating contact between the sealing elements, a braking effect is produced above the shaft and finally a corresponding friction effect, which leads to wear and premature damage of the shaft seal.

On the basis of these indicators, the task of the attached research is to improve the shaft seal while at the same time achieving high reliability and a long service life, even with high vertical loading of the rollers.

This task is solved by means of a shaft seal with the characteristics of Claim 1 and a conveyor roller made in accordance with the characteristics of Claim 2.

The shaft seal made in accordance with the invention has the same composition as the previously described type of seal, which means that on one ring of one of the two sealing elements, the formation of a protrusion is provided - a cam, which has an annular shape and is rotatable and which is directed and extends towards the ring of the other sealing element. It is further provided that the cam in the joint construction of the shaft seal in accordance with the invention is in contact with the ring of the second sealing element and that at the beginning of the rotational movement of the shaft and/or the body of the reel, wear occurs - grinding until a narrow annular gap - a slot is formed between the cam and the ring of the second sealing element. The importance of this idea is reflected in the fact that the shaft seal is primarily a contact seal, which has a place for wear. After a certain time of rotational movement, wear occurs - grinding of the cam on the part between the cam and the opposite ring, and accordingly a narrow annular slot is created, which creates a non-contact space around the entire circumference of the shaft seal. Thus, after a certain "rolling time", a non-contact part is created in the labyrinth seal. The cam will only wear down to a certain extent, in order to achieve the necessary non-contact drive, so that after that the big wear stops - cam grinding. Comparing the usual known shaft seals, where it is possible to achieve a narrow annular slot only with high-precision finishing and assembly, it can be stated that such a procedure significantly raises the production price for similar known shaft seals.

A conveyor pulley made in accordance with the invention has a shaft seal made in accordance with the invention. As soon as the shaft seal starts to rotate without contact, homogeneous - uniform rotation of the conveyor rollers is ensured. This leads to a significant reduction in the wear of the conveyor roller casing, because a basically homogeneous speed of the belt lifter is achieved (for conveyors with a belt) and the falling of the belt downwards is significantly reduced. This is important for conveyors with a larger number of rollers in order to preserve the straight line of the transport device (conveyor belt), in order to build a transport road that is several kilometers long, and it is also important that the production of rollers can include the production of seals with an acceptable low price and that the rollers have a high service life without failure at the same time.

Because the wear - grinding of the cam is right at the beginning of the rotational movement, it does not have too much of a braking effect, which primarily gives the proposed construction with a conical cam an advantage. Thanks to the pointed shape of the initial part of the conical cam, a compromise was achieved between the requirement for low friction and a satisfactory stability, and that after grinding the material of the cam, a blunt point is created on the cam, which is advantageous.

One advantage of the embodiment of the shaft seal according to the invention is that the reel shaft is provided as a stator and the reel body as a rotor.

The advantage is also reflected in the fact that, in accordance with the invention, the sealing path is provided for the shaft seal, where the formation of two boundary walls is provided, which lie opposite each other, and that an internal sealing element is placed on one wall, and an external sealing element is installed on the other wall.

In order to achieve an optimal extension of the sealing path, it is primarily provided that the ring of the inner sealing element and the ring of the outer sealing element can be changed relative to each other in the axial direction of the reel axis.

A further advantage of a shaft seal made in accordance with the invention is that, in the case of multiple cams provided, they form only one on both sealing elements. Then, with a suitable choice of different materials for both sealing elements, safe removal (grinding) of the cams can be achieved without damaging the opposite ring.

In order to ensure a simpler construction and reliable mounting of the shaft seal, the production of the inner sealing element and/or the outer sealing element is provided as one unique piece.

Since the shaft seal made in accordance with the invention functions reliably also under load, it can be primarily used for conveyor rolls, especially for belt or belt conveyors.

Furthermore, the invention will be described in more detail with the help of the attached drawing, as well as a detailed example of execution.

The only attached figure shows a longitudinal section of a shaft fastener, which represents an example made in accordance with the invention. The representation in the picture represents a partial longitudinal section in the axial direction of the conveyor pulley with one generally cylindrical hollow body 1 of the pulley and one shaft 2, which is embedded in the body 1 of the pulley. In the picture, only one side of the conveyor roller is shown, and the opposite side is made in the usual way, completely identical and symmetrical to the side shown. The end of the body 1 of the roller is deformed towards the inside to form the seat 3 of the bearing in which the roller bearing 4 is installed. In order to close the hollow space of the body 1 of the roller, in the area of the bearing next to the roller bearing 3, one cover 5 of the bearing, which is ring-shaped, is installed. This space is closed in the opposite direction, i.e. directed towards the opposite part of the bearing space, by means of a shaft seal made in accordance with the invention.

The shaft seal has an internal sealing element 6 placed on the shaft 2. The internal sealing element 6 is composed together of a first internal hollow cylinder and a second internal hollow cylinder, which rests on the outer side of the first hollow cylinder. The first inner ring 7 is placed on the first hollow cylinder, so that a profile is placed on both sides of the central axis 8, which has an L-shaped cross-section. On the second hollow cylinder, a second inner ring 9 is formed in such a way that an intermediate space 10 is created between the first inner ring 7 and the second inner ring 9, which is in the form of a groove.

The third inner ring 11, which has a small thickness similar to the second inner ring 9, is placed as a continuation - an extension, on the second inner ring 9. These three inner rings 7, 9, 11 are directed with their free ends radially outside the shaft. There is a sealing cover 12 on the inner sealing element 6 in the vicinity of its visible side.

In the shown example performed according to the invention, the first hollow cylinder is made together as one single piece with the first inner ring 7. Likewise, the second hollow cylinder is made together with the second inner ring 9 and the third inner ring 11 as a single piece. It is completely clear that also the entire internal sealing element 6 must be made as a single piece. The material for the internal sealing element 6 must be reinforced with glass fibers made of polyamide, for example the material of the designation PA66 GF30.

The outer sealing element 13 is placed on the body of the reel and is performed in the shown example of a conveyor reel together with the rotary body 1 of the reel and has a rotational movement relative to the shaft 2 and towards the inner sealing element 6. The outer sealing element 13 is a ring element whose cross-sectional profile is Y-shaped and has the first outer ring 14 installed together with it.

The first outer ring 14 is formed on one arm adjacent to the Y-profile and is directed with its free end radially towards the interior. Another outer ring 15 is designed as a foot of Y-profile. Also, the second outer ring 15 is directed with its free end radially towards the interior, i.e. towards the central axis 8. In the space towards the shown arm of the Y-profile, a third outer ring 16 is installed, which is opposite to the first outer ring 14 and the second outer ring 15, i.e. its free end is directed radially towards the outside.

On all three outer rings 14, 15 and 16, the formation of protrusions - ridges 17, 18 and 19 is provided on each. In this, the pointed part of the ridge 17, which is formed on the first outer ring 14, is directed and touches the first inner ring 7. The second ridge 18 formed on the second outer ring 15 is directed towards the second inner ring 9. Finally, the third ridge 19, which is in the same way formed on the third outer ring 16, is directed with its tip towards the third inner ring 11. In the shown example of the embodiment in accordance with the invention, the outer sealing element 13 is made of a material that is relatively softer compared to the material of the inner sealing element 6, i.e. a material that is relatively easy to grind - wear is chosen, for example POM material is used, i.e. polyacetate.

When installing the shaft seal, the cams 17, 18 and 19 are placed in contact with the first inner ring 7, with the second inner ring 9 and with the third inner ring 11 for wear. After the beginning of the rotational movement of the body 1 of the reel, which rotates around the shaft 2, wear begins - rubbing of the outer sealing element 13 over the inner sealing element 6, and on this occasion, due to friction, the points from the cams 17, 18 and 19 are ground until a small narrow annular slot - a gap - is created. After creating an annular slot, the movement of the shaft seal occurs without contact. This so-called "rolling" process, which causes contactless rotation of the shaft seal, takes several days, and with the shaft seal made according to the invention, approximately two days.

Based on this, it is clear that in the initial rolling time, a lot of energy must be used to turn the conveyor rollers, because the lost energy spent on wear - grinding the cams must be compensated. As soon as the annular slots - gaps - are built, there is a corresponding reduction in the energy required for the propulsion system.

When the body 1 of the roller is loaded with some load, for example through the transport of material, deformation of the conveyor roller is caused, which is reflected in the wobbling or tilting of the outer rings 14, 15 and 16 in relation to the inner rings 7, 9, 11. In this case, further wear occurs - grinding of the cams 17, 18 and 19, until non-contact rotation occurs again. After these changes from the state of the loaded body 1 of the roller to the state of the unloaded body of the 1 roller, only changes in the size of the annular slot are caused, without any further contact for wear or grinding. In this way, the aforementioned pumping effect is significantly reduced.

The labyrinth slots of the shaft seal are primarily filled with a lubricating or sealing agent, for example grease. Through the rotation of the body 1 of the reel, the grease will radially move outwards due to the centrifugal force and collect especially in the labyrinth slot in the vicinity of the space near the free end of the first inner ring 7. This will additionally successfully seal the labyrinth slot between the first inner ring 7 and the outer sealing element 13.

When the body of the reel 1 is at rest, the centrifugal effect that moves the grease outwards is omitted. Then it will depend primarily on the relative viscosity of the grease, whether the grease remains and its easy "flowing" based on the force of gravity into the interior of the shaft seal. This means that in the inner part of the shaft seal, the grease seals the labyrinth slots in the space around the free end of the first inner ring 7. In the upper area of the shaft seal, the grease fills the space around the free end of the second outer ring 15 and seals that part of the labyrinth slot. In this way, it is possible to seal and protect against the penetration of dirt and moisture of the body 1 of the reel, not only during operation, but also in a state of rest.

Claims (8)

1. Shaft seal for use with conveyor rollers, especially belt or belt conveyors with one internal sealing element (6) placed on the shaft (2) of the roller, which has at least one ring (7, 9, 11), and one external sealing element (13) placed on the roller body (1), which has at least one ring (14, 15, 16), which is generally set parallel to at least one ring (7, 9, 11) of the internal sealing element (6), characterized by the fact that one of the rings (14, 15, 16) of one of the two sealing elements (13) is intended to form a protrusion - a cam (17, 18, 19), which is ring-shaped and rotating and which is directed towards one of the rings (7, 9, 11) of the second sealing element (6), whereby during the joint production of the cam of the sealing shaft in contact with with one ring (7, 9, 11) of the second sealing element (6) and after the beginning of the rotational movement of the shaft (2) and/or body (1) of the reel, grinding of the cam occurs, until a narrow annular slot is formed between the cam (17, 18, 19) and the ring (7, 9, 11) of the second sealing element (6). 2. A roller for a conveyor, especially for a conveyor with a belt or belt, with one hollow body (1) of the roller and one shaft (2) supported by at least two roller bearings (4), indicated by the fact that a shaft seal made in accordance with Claim 1 is placed on the bearing (4). 3. Reel according to Claim 2, characterized in that the cams (17, 18, 19) are conical. 4. A reel according to Claims 2 or 3, characterized in that the shaft (2) is provided as a stator and that the body (1) of the reel is provided as a rotor. 5. A reel according to one or more of the preceding Claims 2 to 4, characterized in that it has a sealing path, in which an inner sealing element (6) is placed on two oppositely formed border walls and an outer sealing element (13) is placed on the other. 6. A reel according to one or more of the previous Claims 2 to 5, characterized in that the rings (7, 9, 11) of the inner sealing element (6) and the rings (14, 15, 16) of the outer sealing element (13) are placed in the axial direction of the shaft (2) so that they can replace each other. 7. Reel according to one or more of the preceding Claims 2 to 6, characterized by the fact that in the case of multiple provided cams (17, 18, 19), they are placed only on one of the two sealing elements (6, 13). 8. A reel according to one or more of the preceding Claims 2 to 7, characterized in that the inner sealing element (6) and/or the outer sealing element (13) are designed to be made of one piece.