Thin-wall bearing and computed tomography device with thin-wall bearing
By using unhardened metal substrates in thin-walled bearings for local laser hardening, forming a high-hard raceway area, the problems of stress and deformation during hardening are solved, and cost-saving and high-precision and smooth bearing performance are achieved. Suitable for rotating parts of computed tomography devices.
Patent Information
- Application Number
- CN202380041572.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-07-14
- Filing Date
- 2023-03-14
- Publication Date
- 2024-12-20
AI Technical Summary
Existing thin-walled bearings are prone to stress and deformation during hardening, resulting in high cost and difficult to ensure operational accuracy and stability, especially in the computed tomography device, the high accuracy and smooth operation requirements of the rotating part are difficult to meet.
Thin-walled bearings are made of unhardened metal substrates, and locally laser hardened only in areas in contact with the rolling elements, forming high hardness raceway areas, reducing overall deformation, and using cheap steels such as 1.7228 or 1.7225 grade steel, improves the microstructure through tempering.
Cost savings and thermal deformation are achieved, and bearing performance with high accuracy, stability and high tilt stiffness are ensured. It is suitable for rotating parts of computed tomography devices.
Smart Images
Figure CN119173699A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a thin-walled bearing, in particular for use in a computed tomography device, comprising at least one outer ring, at least one inner ring and a plurality of spherical rolling elements, wherein at least one inner ring has an inner diameter greater than 700 mm. Background Art
[0002] DE 10 2009 056038 A1 describes a thin-walled bearing and a method for producing a bearing ring for a thin-walled bearing from a material in wire form. The wire is rolled up, bent, and the free ends are welded together. The resulting solid ring is then annealed and finally cold rolled and optionally hardened.
[0003] Thin-walled bearings have an inner ring inner diameter D that is larger than the distance A between the inner diameter and the outer diameter of the bearing. i rolling bearing (viewed in cross section). In particular, A / D i Ratio = 1:30 to 1:150.
[0004] DE 10 2007 049 071 A1 describes a wire raceway bearing having two concentrically arranged support rings, which have guide wires in mutually facing recesses, between which rolling elements roll on associated raceways. The wire raceway bearing is designed as a four-point ball bearing and is used as a rotary joint in a computed tomography device.
[0005] DE 10 2004 062 116 B3 discloses a bearing device for a medical device, such as a computer tomography device, which has a one-piece inner ring and a one-piece outer ring, each of which has a hollow cylindrical basic contour.
[0006] DE 10 2017 222 208 B3 describes a computer tomography device and a method for arranging a bearing ring of a rolling bearing. It is pointed out that the computer tomography device usually has a fixed part and a rotating part, wherein the rotating part has a radiation source for X-rays and an X-ray detector that interacts with the radiation source. The rotating part can have a mass of, for example, about 600 kg to 900 kg, and the rotating part can rotate at a speed of about 60 revolutions per minute to 240 revolutions per minute. Very precise, smooth and noiseless operation of the rotational motion is crucial. The rotational motion of the rotating part can be driven by means of a direct drive or by means of a transmission belt that interacts with the pulley of the rotating part. The rolling bearing can be used to pivot the rotating part relative to the fixed part. The rolling bearing has a plurality of rolling elements and a plurality of raceways for rolling the rolling elements.
[0007] A high degree of running accuracy, extreme smoothness, freedom from play and a high degree of tilting rigidity are essential for producing high-quality images. Until now, bearing rings made of high-purity and therefore expensive steel grades, which are usually fully hardened, have been used for this purpose. During the hardening process, the bearing rings often develop stresses and deformations. Summary of the invention
[0008] It is therefore an object of the present invention to provide a suitable thin-walled bearing which brings about cost savings in production and reduces thermal deformation during the hardening process.
[0009] The object is achieved by a thin-walled bearing comprising at least one inner ring, at least one outer ring and a plurality of spherical rolling elements, wherein at least one inner ring has an inner diameter D greater than 700 mm. i , wherein at least one outer ring and at least one inner ring are made of an unhardened metal substrate having a hardness of less than 58 HRC, wherein at least one outer ring and at least one inner ring each form at least one raceway region in contact with rolling elements, and wherein the substrate is laser hardened in at least one raceway region and the raceway region has a hardness of at least 58 HRC.
[0010] Since at least one inner ring and at least one outer ring are only partially laser hardened, deformations of the bearing rings are minimized. The inexpensive, unhardened metal substrate is hardened only in the areas that are in contact with the rolling elements and form the raceways for them. This results in significant cost savings in the production of thin-walled bearings.
[0011] However, in order to improve the microstructure, it has proven effective to temper the metal substrate to a hardness of 250+100 HV before laser hardening.
[0012] Preferably, the metal substrate is made of steel having the following proportions:
[0013] 0.38 wt.% to 0.56 wt.% C,
[0014] 0.3 to 1.2 wt% of Mn,
[0015] 0.9 to 1.2 wt% Cr,
[0016] 0.15 wt% to 0.30 wt% Mo,
[0017] The remainder of iron and unavoidable impurities or other elements such as Si, Al, P, S, Pb has a proportion of less than 0.5% by weight. This is inexpensive, can be laser hardened and can be used for the thin-walled bearing according to the invention. In particular, steels of the 1.7228 (50CrMo4) or 1.7225 (42CrMo4) grades have proven to be effective.
[0018] Preferably, there is an outer ring and an inner ring, each of which has two raceway regions arranged separately from each other and extending in an annular manner and parallel to each other. The two raceway regions are preferably separated from each other by an annular groove. The groove serves as a lubricant reservoir and prevents the heat-affected zones of the two raceway regions from overlapping.
[0019] Alternatively, it has proven effective to have two outer rings and / or two inner rings, each of which has an annular raceway region. The two outer rings and / or the two inner rings can have local recesses in the region where their raceways adjoin each other.
[0020] The free surface of at least one raceway region forming a raceway for rolling elements can be machined and / or rolled. The free surface of at least one raceway region forming a raceway for rolling elements is in particular honed.
[0021] At least one raceway region preferably has different thicknesses when viewed across a cross section through at least one outer ring or at least one inner ring.Preferably, the penetration depth of the laser hardening in the substrate reaches its maximum penetration depth in the region of the contact angle series.
[0022] A computed tomography device comprising at least one thin-walled bearing according to the invention has proven itself to be able to achieve a high degree of running accuracy, a very high running smoothness, no play and a high degree of tilting rigidity in relation to a thin-walled bearing. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figures 1 to 4 It is intended to illustrate by way of example a thin-walled bearing according to the invention. In the drawings:
[0024] Figure 1 shows a section through a first thin-walled bearing having an outer ring and an inner ring;
[0025] Figure 2 Shown according to Figure 1 An enlarged detail of the first thin-walled bearing in the cross-sectional surface area;
[0026] Figure 3 shows a section through a second thin-walled bearing having two outer rings and two inner rings; and
[0027] Figure 4Shown according to Figure 3 Magnified detail of the second thin-walled bearing in the cross-sectional surface area. DETAILED DESCRIPTION
[0028] Figure 1 A section through a first thin-walled bearing 1 having an outer ring 3 and an inner ring 2 is shown. Furthermore, there are a plurality of spherical rolling elements 4. The inner ring 2 has an inner diameter D greater than 1 m. i The outer ring 3 and the inner ring 2 are made of an unhardened metal substrate 6 having a hardness of less than 58 HRC (see Figure 2 ). The outer ring 3 and the inner ring 2 each form at least one raceway region 7a, 7b, 7c, 7d in contact with the rolling element 4. The substrate 6 is laser hardened in the raceway regions 7a, 7b, 7c, 7d, and the raceway regions 7a, 7b, 7c, 7d have a hardness of at least 58 HRC. A / D i The ratio is in the range of 1:30 to 1:150, wherein the inner diameter D of the thin-walled bearing 1 i The distance A from the outer diameter (seen in cross section) is noted. The outer ring 3 and the inner ring 2 each have two raceway regions 7a, 7b; 7c, 7d arranged apart from one another and extending annularly and parallel to one another, which are separated from one another by annular grooves 9a, 9b.
[0029] Figure 2 Shown according to Figure 1 The first thin-walled bearing 1 has a cross-sectional surface area (see Figure 1 The contact angle is 5 Figure 2 The hardening depth in the substrate 6 reaches its maximum hardening depth in the region of the raceway regions 7a, 7b, 7c, 7d intersecting the contact angle 5. The free surfaces 8 of the raceway regions 7a, 7b, 7c, 7d in each case form a raceway for the rolling elements 4.
[0030] Figure 3 A section through a second thin-walled bearing 1 ' is shown with two outer rings 3a, 3b and two inner rings 2a, 2b. In addition, there are a plurality of spherical rolling elements 4. The inner rings 2a, 2b have an inner diameter D greater than 700 mm. i The outer rings 3a, 3b and the inner rings 2a, 2b are made of an unhardened metal substrate 6 having a hardness of less than 58 HRC (see Figure 4 ). The outer rings 3a, 3b and the inner rings 2a, 2b each form a raceway region 7a, 7b, 7c, 7d in contact with the rolling element 4. The substrate 6 is laser hardened in the raceway regions 7a, 7b, 7c, 7d, and the raceway regions 7a, 7b, 7c, 7d have a hardness of at least 58 HRC. A / D iThe ratio is in the range of 1:30 to 1:150, wherein the inner diameter D of the thin-walled bearing 1' i The distance A from the outer diameter (seen in cross section) is noted. The outer rings 3a, 3b and the inner rings 2a, 2b each have an annular raceway region 7a, 7b; 7c, 7d.
[0031] Figure 4 Shown according to Figure 3 The second thin-walled bearing 1' has a cross-sectional surface area (see Figure 3 The contact angle is 5 Figure 4 The hardening depth in the substrate 6 reaches its maximum hardening depth in the region of the raceway regions 7a, 7b, 7c, 7d intersecting the contact angle 5. The free surfaces 8 of the raceway regions 7a, 7b, 7c, 7d in each case form a raceway for the rolling elements 4.
[0032] Reference numerals list
[0033] 1. 1' thin-walled bearing
[0034] 2, 2a, 2b Inner ring
[0035] 3, 3a, 3b Outer ring
[0036] 4 Rolling elements
[0037] 5. Contact angle
[0038] 6 Substrate
[0039] 7a, 7b, 7c, 7d Raceway area
[0040] 8 Raceway area or free surface of the raceway
[0041] 9a, 9b Annular groove
[0042] A Distance
[0043] D I inner diameter
Claims
1. A thin-walled bearing (1, 1'), comprising at least one inner ring (2, 2a, 2b), at least one outer ring (3, 3a, 3b) and a plurality of spherical rolling elements (4), wherein: The at least one inner ring (2, 2a, 2b) has an inner diameter (D i ), wherein the at least one outer ring (3, 3a, 3b) and the at least one inner ring (2, 2a, 2b) are made of an unhardened metal substrate (6) having a hardness of less than 58 HRC, wherein the at least one outer ring (3, 3a, 3b) and the at least one inner ring (2, 2a, 2b) each form at least one raceway area (7a, 7b, 7c, 7d) in contact with the rolling element (4), and wherein the substrate (6) is laser hardened in at least one of the raceway areas (7a, 7b, 7c, 7d) and the raceway areas (7a, 7b, 7c, 7d) have a hardness of at least 58 HRC.
2. The thin-walled bearing (1, 1') according to claim 1, wherein: The metal substrate (6) is made of steel having the following proportions: 0.38 wt.% to 0.56 wt.% C, 0.3 to 1.2 wt% of Mn, 0.9 to 1.2 wt% Cr, 0.15 wt% to 0.30 wt% Mo, The balance of iron and inevitable impurities or other elements such as Si, Al, P, S, Pb has a proportion of less than 0.5 wt %.
3. The thin-walled bearing (1) according to one of claims 1 or 2, wherein: An outer ring (3) and an inner ring (2) are provided, each having two raceway regions (7a, 7b; 7c, 7d) which are arranged separately from one another and extend in an annular manner and parallel to one another.
4. The thin-walled bearing (1) according to claim 3, wherein: The two raceway regions (7a, 7b; 7c, 7d) are spaced apart from one another by an annular groove (9a, 9b).
5. The thin-walled bearing (1') according to one of claims 1 or 2, wherein: There are two outer rings (3a, 3b) and / or two inner rings (2a, 2b), each of which has an annular raceway region (7a, 7b, 7c, 7d).
6. The thin-walled bearing (1, 1') according to one of claims 1 to 5, wherein: The free surface (8) of at least one of the raceway regions (7a, 7b, 7c, 7d) forming a raceway for the rolling elements (4) is machined and / or rolled.
7. The thin-walled bearing (1, 1') according to claim 6, wherein: The free surface (8) of at least one of the raceway regions (7a, 7b, 7c, 7d) forming a raceway for the rolling elements (4) is honed.
8. The thin-walled bearing (1, 1') according to one of claims 1 to 7, wherein: At least one of the raceway regions (7a, 7b, 7c, 7d) has a different thickness when viewed across a cross section through the at least one outer ring (3, 3a, 3b) or the at least one inner ring (2, 2a, 2b).
9. A computer tomography apparatus comprising at least one thin-walled bearing (1, 1') according to one of claims 1 to 8.