DE102015204433B4 - Adhesive bonding of roller bearing and shaft and disassembly process - Google Patents

Abstract

Method, comprising: providing (A) a shaft (5) with a roller bearing (7), wherein a deactivatable adhesive (9) between an inner surface (11) of an inner ring (13) of the roller bearing (7) and an outer surface (15) of Shaft (5) fixes the roller bearing (7) on the shaft (5); heating (17) the deactivatable adhesive (9); applying a voltage (U) via the adhesive (9); separating (20) from the shaft (5) and roller bearings (7); the heating of the deactivatable adhesive (9) and the application of the voltage (U) via the adhesive (9) for deactivating the adhesive being carried out with a time overlap.

Description

The present invention relates to a method, in particular a method for disassembling and optionally assembling a shaft and a roller bearing, and also relates to a system made up of a shaft, a roller bearing and a deactivatable adhesive.

Bearings, such as roller bearings, can be fixed to a shaft or shaft in a number of ways. An example is an interference fit. Such an interference fit requires a great deal of assembly effort since the shaft is slightly larger in diameter than the inner ring of the bearing. Normally, mounting is performed by applying a large axial force or by expanding the inner ring of the bearing by heating. If such an assembled bearing is to be disassembled after some time in service, the axial force required for this can be several times higher than the force required for assembling. Destruction of the bearing or the shaft often makes disassembly possible.

Another option for fixing or mounting a rolling bearing on a shaft is to use a cone-shaped sleeve. This requires additional parts, which are very expensive and require additional space. In this case, either the shaft has to be a little smaller or the bearing has to be a little bigger, compared to the press fit. The beveled or conical sleeve can then be inserted between the ring of the bearing and the outer surface of the shaft for fixation.

In other cases only axial clamping is used with the risk of relative movement of the bearing parts relative to the shaft or housing.

DE 10 2010 004 792 A1 teaches a method for fixing a bearing ring on or in a component by means of an adhesive connection.

DE 10 2007 052 574 A1 teaches another method for fixing a bearing ring on or in a component by means of an adhesive connection.

EP 2 524 150 B1 teaches a third method for fixing a bearing ring on or in a component by means of an adhesive connection.

Conventional methods for assembling a bearing and shaft or conventional bearing and shaft systems thus have numerous disadvantages. It is an object of the present invention to provide a method for disassembling and assembling a rolling bearing and a shaft and a rolling bearing and a shaft system, which is easy to perform, requires few additional components, and handling of the bearing and shaft guaranteed, which avoids damage or even destruction of these components.

According to one embodiment of the present invention, a method (in particular for disassembling and/or assembling shaft and roller bearing) is provided, which starts from a shaft with a roller bearing, with a deactivatable adhesive (its adhesive force or adhesive effect reduced in a targeted manner with certain effects can be fixed) between an inner surface (e.g. cylindrical inner surface) of an inner ring of the rolling bearing (which can also have a plurality of rolling elements, a rolling element cage and an outer ring) and an outer surface (e.g. a cylindrical outer surface) of the shaft, the rolling bearing is fixed on the shaft. Thus, the method assumes an assembled state of the shaft and the roller bearing. The method further comprises heating (e.g. by electrical heating, radiant heating or the like) the deactivatable adhesive, applying a voltage across the adhesive (so that a potential difference is established between two spaced points of the adhesive) and separating (i.e. in particular spatially Separating (e.g. moving away from each other) the shaft and roller bearing.

The shaft may comprise a cylindrical shaft made of steel, for example. Rolling bodies of the rolling bearing can have, for example, a cylindrical shape, a truncated cone shape, a spherical shape or, for example, a barrel shape. The adhesive can be deactivated to reduce an adhesive effect and, in special cases, can also be activated to establish the adhesive effect. According to particular embodiments, the adhesive can only be deactivated without being able to be activated. The adhesive can be deactivated by heating and (simultaneously) applying an electrical voltage across the adhesive. For this purpose, the adhesive can have a suitable material composition, in particular a thermoplastic material. The shaft and roller bearing can be separated without damaging or even destroying the shaft and/or roller bearing. After deactivation (and in particular in a heated, soft or viscous or liquid state), the adhesive can be removed from the components, in particular pulled off. This means, for example, that a system consisting of a shaft and roller bearing can be disassembled in order to replace one of the components, for example, without removing the other component to damage. This can save costs.

The heating of the deactivatable adhesive and the application of the voltage across the adhesive to deactivate the adhesive take place with an overlap in time. Thus, during a certain period of time the adhesive is heated and at the same time the voltage is applied across the adhesive. The adhesive can only be deactivated if these two treatment measures coincide or are carried out simultaneously, ie its adhesive force on the components can be reduced. Thus, dedicated measures are required to deactivate the adhesive, which can prevent accidental deactivation of the adhesive.

Furthermore, heating and voltage application can be accomplished by conventionally available equipment. A simple method can thus be provided.

The tension can be applied in particular between the inner ring of the rolling bearing and the shaft. A radially directed field can thus be formed within the adhesive or the adhesive layer between the inner ring and the shaft in an intermediate space between the inner ring and the shaft. For example, the field may be radially outward or radially inward. In other embodiments, for example, the field may also have axial or circumferential components. The field or the voltage can be applied between the inner ring and the shaft in a simple manner by contacting both the inner ring and the shaft with two poles of a voltage source. After or during the heating and the application of the voltage, the adhesive strength of the adhesive on the shaft or the inner ring can be less than 0.5 N/mm ² . The bond strength may be reduced only during heating and application of voltage, but may increase to an original value once heating and application of voltage are terminated or when the adhesive returns to, for example, room temperature or an original temperature is. The adhesive strength can decrease and/or increase reversibly, depending on the treatment condition of the adhesive.

Furthermore, in the method, the adhesive can be removed from the bearing and shaft, especially in the heated state of the adhesive, in which state the adhesive is soft or liquid. When the adhesive is soft, adhesive removal can be performed without damaging the bearing or shaft. A voltage does not necessarily also have to be applied during the removal of the adhesive. Active heating of the adhesive does not have to be necessary when removing the adhesive either, but the adhesive can still have an elevated temperature, so that it is still soft or viscous. Dangers for a user can thus be reduced since voltages and heaters can be switched off.

During the heating, the adhesive may be heated to a temperature between 50°C and 120°C, particularly between 60°C and 70°C, to reduce the hardness of the adhesive, particularly to liquefy the adhesive. Such temperatures are easily achievable with conventional heaters. The voltage can be a DC voltage and can have a magnitude of between 20 volts and 80 volts, in particular between 40 volts and 50 volts. This means that conventionally available electrical devices can be used to generate the voltage and the risk to the user can be reduced.

To obtain the shaft and roller bearing fixed relative to one another, the method can also comprise an assembly step, wherein adhesive in a deformable, in particular liquid, state is applied to the inner surface of the inner ring of the roller bearing and/or to the outer surface of the shaft. Thereafter, an axial relative displacement of the roller bearing and the shaft can take place in order to arrange the roller bearing on the shaft (and to adjust it there in a particularly suitable manner). Furthermore, the adhesive can harden and also build up adhesive forces both towards the shaft and towards the inner ring in order to firmly connect the bearing and shaft to one another. The adhesive can be cured in particular by cooling the adhesive; the adhesive can be deformable in the heated state.

According to another embodiment of the present invention, a system is provided which has a shaft, a roller bearing and a deactivatable adhesive. In this case, the adhesive is present between an inner surface of an inner ring of the rolling bearing and an outer surface of the shaft and fixes the rolling bearing on the shaft. Furthermore, the deactivatable adhesive can be deactivated by heating and applying a voltage across the adhesive, so that its adhesive force on the roller bearing or shaft decreases, in order to enable the shaft and roller bearing to be disassembled.

It should be understood that features which are described or provided individually or in any combination in connection with a method, in particular called disassembly method, or assembly method, are also applicable to a system of shaft, roller bearing and adhesive according to embodiments of the present invention and vice versa.

A thickness of the adhesive between the inner surface of the inner ring and the outer surface of the shaft can be between 1/100 mm and 1/10 mm. A very thin film of adhesive can thus be provided, which can enable relatively exact orientation or adjustment during an assembly process of bearing and shaft. Furthermore, the thin layer of adhesive can have elastic properties (in particular in the solidified state), so that a vibration, for example of the shaft, is transmitted to the bearing in a damped manner. Furthermore, the adhesive can represent a thermal insulator, so that heat transfer between the shaft and the inner ring of the roller bearing can also be reduced. Further advantages can be achieved in this way. The adhesive can be an electrical insulator, can be thermoplastic and in particular can comprise a polyamide melt. Thus, those skilled in the art can easily carry out the present invention.

To assemble the shaft and bearing, the adhesive can be activated after the bearing has been placed in the correct position relative to the shaft. For disassembly, the adhesive can be deactivated by applying a higher temperature and a defined current or voltage at the same time. In this case, these two measures, ie heating and applying a voltage, are to be used at the same time. Only one measure will not lead to a deactivation of the adhesive. After applying a current or voltage and heating to a certain temperature, the roller bearing can be easily dismantled or removed from the shaft.

Embodiments of the present invention provide a very easy and cost-effective method for assembling or disassembling a bearing or a bearing and shaft system. The adhesive in the gap between the two parts can also reduce or even prevent corrosion of the contact surfaces. Different materials (e.g. steel, polymer) for the rolling bearing and the shaft can easily be used and glued together. Lower requirements can be placed on the roughness of the contact surfaces compared to conventional methods and systems. The dismantled parts, ie the shaft and the roller bearing, can be used again since damage during dismantling can be reduced or completely avoided. This can be a great advantage when the mounted rolling bearing needs to be readjusted in terms of positioning or orientation after initial mounting.

An embodiment of the present invention will be explained below with reference to the accompanying drawings. The invention is not limited to the illustrated or described embodiments.

The figure illustrates in a schematic sectional view a method for dismantling according to an embodiment of the present invention, wherein a system according to an embodiment of the present invention is dismantled.

The system 1, which is illustrated in method step A, B and C of the method for disassembly in a schematic sectional view (through an axis of rotation 3 of the shaft 5), comprises the shaft 5, for example a cylindrical steel shaft, a roller bearing 7 and a deactivatable adhesive 9 , which is present between an inner surface 11 of an inner ring 13 of the roller bearing 7 and an outer surface 15 of the shaft 5 and fixes the roller bearing 7 on the shaft 5 . The roller bearing also includes roller bodies 17, which have a cylindrical shape, a truncated cone shape, a barrel shape or a spherical shape, for example, and an outer ring 19, the inner ring 13 being able to rotate about the axis of rotation 3 relative to the outer ring 19, the roller bearings 17 being on a Inner surface of the outer ring 19 and an outer surface of the inner ring 13 roll.

The thickness d of the adhesive 9 can be 1/100 mm to 1/10 mm, for example. Other values are possible. Method step A shows an assembled or mounted state of roller bearing 7 and shaft 5, in which the adhesive 9 exerts an adhesive force both on the inner ring 13 of the roller bearing 7 and on the outer surface 15 of the shaft 5, so that shaft 5 and roller bearing 7 are firmly connected.

Method step B is carried out to disassemble or dismantle the roller bearing 7 and the shaft 5, with heat being supplied to the adhesive 9, for example by a radiation source or a convection source, such as a hair dryer, as is shown schematically with reference number 17. For this purpose, the shaft 5 could also be (uniformly) heated. The heat supply 17 can heat the adhesive 9 to a temperature of approximately 65°C. A voltage U is applied between the inner ring 13 of the roller bearing 7 and the shaft 5 simultaneously with the heating of the adhesive 9 or at least with a temporal overlap. The voltage U can be a DC voltage of, for example, 48 volts if, for example, a polyamide melt is used as the adhesive 9 .

The adhesive 9 can be deactivated by the simultaneous heating and application of the voltage U via the adhesive 9, so that its adhesive force is greatly reduced (eg to a value that is smaller by a factor of 10 to 100). A residual strength of less than 0.05 or 0.1 N/mm ² of the adhesive 9 can still be achieved, for example, by means of heating and applying voltage. The voltage U can be set, for example, in such a way that the inner ring 13 is positively charged in relation to the shaft 5, as indicated by “plus” and “minus” symbols in method step B. In other embodiments, the voltage is applied with the opposite sign. In still other embodiments, the voltage can be applied between two axially (along the axis of rotation 3) shifted points. Since the adhesive 9 can act as an electrical insulator, an excessively large current (eg, less than 1 mA) does not need to flow due to the voltage.

Method step C shows a removal of the roller bearing 7 from the shaft 5 after the adhesive 9 as shown in method step B has been deactivated. The deactivation can initially reduce the adhesive force, so that the roller bearing 7 and the shaft 5 can be displaced axially relative to one another, for example in a direction that is provided with reference number 20 . After deactivation or during deactivation or while the adhesive 9 is still kept at a certain elevated temperature, the adhesive 9 can be soft, viscous or liquid, so that it can be easily removed from the shaft 5 by applying a force 21, for example. that is, can be deducted. Both the shaft 5 and the roller bearing 7 can continue to be used for other applications, since damage to them can be reduced or avoided due to the damage-free dismantling.

In the disassembly process, de-sticking can be achieved at the push of a button (by heating and applying voltage) between the roller bearing and the shaft. The adhesive bond can come loose if, for example, an electrical DC voltage of 48 volts is applied and the adhesive joint is heated to 65°C at the same time. The combination of both factors is decisive here: The electrical voltage or heating mentioned alone does not cause any detachment. After the treatment (heating and application of tension) of the bonded joint, the bond strength is greatly weakened. This leads to an adhesive fracture. While it is still warm, the adhesive can then be detached from the component as a closed film without leaving adhesive residue on the previously joined materials. For example, steel (achieved strength 9.7 MPa), structural steel ST37 (strength 7.0 MPa), aluminum (strength 14.2 MPa) or plastic materials can be used as joining materials.

Reference List

1

system

3

axis of rotation

5

Wave

7

roller bearing

9

deactivatable adhesive

11

inner surface of the inner ring

13

Inner ring of the rolling bearing

15

outer surface of the shaft

17

heat application

19

Outer ring of the rolling bearing

20

direction of movement

21

application of force

u

DC voltage

i.e

distance or gap width

Claims (9)

Method comprising: Providing (A) a shaft (5) with a roller bearing (7), with a deactivatable adhesive (9) between an inner surface (11) of an inner ring (13) of the roller bearing (7) and an outer surface (15) of the shaft (5) fixed the roller bearing (7) on the shaft (5); heating (17) the deactivatable adhesive (9); Applying a voltage (U) across the adhesive (9); Separating (20) from shaft (5) and roller bearing (7); the heating of the deactivatable adhesive (9) and the application of the voltage (U) via the adhesive (9) for deactivating the adhesive being carried out with a time overlap. procedure according to claim 1 , where the stress is applied between the inner ring of the rolling bearing and the shaft. Method according to one of the preceding claims, wherein when heating and applying the voltage an adhesion strength of the adhesive (9) on the shaft (5) or the inner ring (13) is less than 0.5 N/mm^2. A method according to any one of the preceding claims, further comprising: Removal (21) of the adhesive (9) from the bearing (7) and shaft (5), in particular when the adhesive is in the heated state, in which the adhesive is soft or liquid. Method according to any one of the preceding claims, wherein heating is carried out to a temperature of between 50°C and 120°C, in particular between 60°C and 70°C, in order to reduce the hardness of the adhesive (9), in particular in order to harden the adhesive liquefy, the voltage (U) being a DC voltage and having a magnitude of between 20 V and 80 V, in particular between 40 V and 50 V. The method according to any one of the preceding claims, wherein providing the shaft with the rolling bearing comprises: Application of the adhesive (9) in the deformable, in particular liquid, state to the inner surface (11) of the inner ring (13) of the rolling bearing (7) and/or to the outer surface (15) of the shaft (5); Relative axial displacement (20) of the rolling bearing (7) and the shaft (5) in order to position the rolling bearing on the shaft; and Curing of the adhesive (9). System (1) comprising: a shaft (5); a rolling bearing (7); and a deactivatable adhesive (9), which is present between an inner surface (11) of an inner ring (13) of the roller bearing (7) and an outer surface (15) of the shaft (5) and fixes the roller bearing (7) on the shaft (5). ; wherein the deactivatable adhesive (9) can be deactivated by heating and simultaneously applying a voltage (U) across the adhesive, so that its adhesive force on the roller bearing or shaft decreases. system according to claim 7 , wherein a thickness (d) of the adhesive between the inner surface (11) of the inner ring and the outer surface (15) of the shaft is between 1/100 mm and 1/10 mm. system according to claim 7 or 8th , wherein the adhesive (9) is an electrical insulator, is thermoplastic and in particular has a polyamide melt.

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