Patent Application
20230119200
The present disclosure relates generally to bearing units provided with a collar for clamping a radially inner ring of the bearing units on a rotating shaft.
Such bearing units may be suitable for applications in the manufacturing industry, and for the agricultural industry.
Exemplary embodiments of the present disclosure will be described with reference to the attached drawings, in which:
Bearing units provided with rolling elements and systems for clamping the said unit on a rotating shaft are known.
Bearing units may be used to allow the relative movement of a component or assembly with respect to another component or assembly. Bearing units generally have a first component, for example a radially inner ring, which is fixed to a first component, for example a rotating shaft, and a second component, for example a radially outer ring, which is fixed to a second component, for example a stationary housing. Typically, the radially inner ring is rotatable, while the radially outer ring is stationary, but in many applications the outer element may rotate and the inner element may be stationary. In any case, in bearing units, the rotation of one ring with respect to the other ring is allowed by a plurality of rolling elements positioned between a cylindrical surface of the first component and a cylindrical surface of the second component, normally called raceways. The rolling elements may be balls, cylindrical or tapered rollers, needle rollers, or similar rolling elements.
Also known are bearing units provided with a clamping collar for mounting on a rotating shaft. Known clamping collars generate excessive noise and vibrations that may result in damage to the shaft on which the bearing unit is installed. Known collars may be shaped at an end portion of the radially inner ring with a plurality of circular sector segments spaced by grooves, namely a series of “grooved fingers” on which the clamping collar engages. The greater flexibility of these circular sector segments facilitates the flexing of the segments against the shaft when the clamping collar is installed and tightened.
Because a thickness of the circular sector segments may not be reduced sufficiently to ensure the necessary flexibility without increasing the risk of excessively weakening the end portion of the radially inner ring, known collars do not sufficiently reduce noise or vibrations.
Furthermore, known radially inner rings are hardened using a case-hardening heat treatment in order to ensure correct operation of the bearing unit. In particular, a hertzian contact between the rings of the bearing unit and the rolling elements (balls, rollers, etc.) requires contact surfaces, which are sufficiently hardened so as to avoid the deformations and consequent vibrations and noise. Case hardening heat treatments, however, reduces the flexibility of the circular sector segments in contact with the clamping collar. Thus, known collars cannot maintain an optimum flexibility while reducing noise and vibrations. This increases a risk that the shaft or radially inner ring may damage.
Therefore, a need exists for a bearing unit provided with a clamping collar such that the clamping action has reliable mechanical strength, ensures concentricity of the shaft and the radially inner ring, does not generate excessive noise and/or vibrations, and is sustainable in economic terms.
An object of the present disclosure is to provide a bearing unit having a clamping collar that achieves a more efficient clamping action and which is therefore not subject to the aforementioned drawbacks.
According to the present disclosure, a radially inner ring may include an end portion that may not contact with a clamping collar having a plurality of circular sector segments spaced apart by grooves. The collar may be configured to establish a concentric and stable fix between the radially inner ring and a rotating shaft.
A radially inner ring consistent with this disclosure may be subject to a localized induction-hardening heat treatment. In this way, a necessary hardness at surfaces of the radially inner ring that contact a plurality of rolling elements of the bearing unit is ensured, while a terminal end of the radially inner ring may be sufficiently pliable. This improves flexibility of portions of the terminal end that are gripped by the concentric clamping collar.
In particular, bearing unit according to the present disclosure is provided with rolling elements and is provided with an optimized clamping system which involves the use of a concentric collar which is able to grip and clamp onto the shaft a plurality of circular sector segments which are spaced by grooves in the radially inner ring, together with an innovative heat treatment for the radially inner ring.
With reference to
Throughout this disclosure and the claims, the terms and the expressions indicating positions and orientations such as “radial” and “axial” are understood as referring to the central rotation axis X of bearing unit 30.
In various embodiments, radially outer ring 31 may be provided with a radially outer raceway 31′, and radially inner ring 33 may be provided with at least one radially inner raceway 33′ for allowing rolling of row of rolling elements 32 interposed between radially outer ring 31 and radially inner ring 33. For simplicity of illustration, reference number 32 may be attributed both to individual rolling elements of the row of rolling elements and to the row of rolling elements.
In various embodiments, bearing unit 10 may be provided with a seal 35 for sealing off bearing unit 10 from an external environment.
A concentric clamping collar 20 may be included and clamp an end portion 36 of radially inner ring 33 on a rotating shaft (not shown).
As illustrated in
Collar may be provided with a raised groove 22 Collar 20 may be installed over radially inner ring 33 and, in particular, over one or more circular sector segments 40 to lock radially inner ring 33 of bearing unit 10 onto the shaft. Collar 20 may thus be locked in a concentric manner without causing damage and/or burring during installation while exerting a 360 degree clamping force on the shaft with a minimum displacement of one or more arms 23, 24 of collar 20 so as to reduce vibrations experienced during use.
Advantages of locking collar 20 concentrically with the shaft include coincidence between the shaft and axis of symmetry (X) of bearing unit 10 and a reduction of corrosion of collar 20 and inner ring 33 due to friction. Furthermore, a nominal limit of speed and a nominal limit of load of bearing unit 10 do not depend on a tolerance of the shaft, a constant or alternate direction of rotation may be applied during operation/assembly, lower vibration levels do not damage the shaft, and assembly may be fast and easy.
With reference to
With induction-hardening specific surfaces of inner ring 33 may be hardened. In various embodiments, the surfaces surrounding one or more raceways 33′ in particular. This different heat treatment may result in a reduction in costs of hardening because less surface area may be treated and a quantity of material treated is less than that of case-hardening and other similar heat treatment processes.
A material of inner ring 33 may be a hardening steel, for example, a 100Cr6 steel, which may also reduce cost.
With reference to
In order to optimize induction-hardening heat treatment, an axial length K1 of first zone R may embrace an axial length of raceways 33′. In various embodiments, axial length K1 may be greater than or equal to the axial length of the raceways 33′. Moreover, a hardening depth of zone R, namely the thickness of the material which must ensure high hardness values, may be equal to at least 10% of a thickness T of radially inner ring 33 along axial length K1.
Moreover, if K defines an entire axial length of portion 37, the axial length of each of zone D1 and zone D2 may be equal to (K−K1)/2. In various embodiments, (K−K1)/2 may be greater than 2 mm.
With reference to
Finally and according to a preferred embodiment, a hardness of zones R, D1, D2, and A may be as shown in the table below:
In various embodiments, zone R and zones D1 and D2, which may be subjected to an induction-hardening heat treatment, may reach a high hardness, each having a maximum hardness of up to 64 HRC. Zone R may have a minimum hardness of 56 HRC and D1, D2 may have a minimum hardness of 50 HRC. Zone A, which may not be subjected to an induction-hardening heat treatment, may have a maximum hardness of 45 HRC. Therefore, circular sector segments 40, which may be included in or overlap with zone A, may be made using a material that is pliable. Such material may have an optimum flexibility in response to a clamping action of concentric collar 20.
By exposing a portion of inner ring 33 to an induction-hardening heat treatment, the quality of the clamp between collar 20 and inner ring 33 is improved performance of the clamping system in terms of the power which can be transmitted and the vibration levels. The circular sector segments are more flexible and as a result, for the same tightening torque of the screws which act on the collar, the closing action of the circular sector segments may be increased.
In addition to exemplary embodiments described in this disclosure, it is to be understood that numerous additional variants exist. It must also be understood that these exemplary embodiments are only examples and do not limit either the scope of the disclosure, its applications, or its possible configurations. On the contrary, although descriptions provided above enables a person of ordinary skill in the art to implement the present disclosure consistent with at least one exemplary configuration, it must be understood that numerous variations of the components described are feasible, without thereby departing from the scope of the disclosure, as defined in the accompanying claims, interpreted literally and/or in accordance with their legal equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020000007048 | Apr 2020 | IT | national |
This application is based on and claims priority to European International application No. PCT/EP2021/058728 filed on Apr. 1, 2021 and Published as WO2021/198475 and Italian Patent Application No. 102020000007048 filed on Apr. 3, 2020, under 35 U.S.C. § 119, the disclosure of which is incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/058728 | 4/1/2021 | WO |
