Axle apparatus and outer race hub heat treatment method therefor

Abstract

The present invention relates to an axle apparatus and an outer race hub heat treatment method therefor, the axle apparatus comprising: a ball tiltably connecting an inner race and an outer race hub; and a bearing supporting the outer race hub. The outer race hub comprises an annular wall part having an outer race groove formed in the inner circumferential surface thereof, and a bearing seat surface formed on the outer circumferential surface thereof. The annular wall part comprises: a non-heat treatment portion; a first heat treatment portion having a different structure from the non-heat treatment portion by means of heat treatment applied to the outer race groove; and a second heat treatment portion having a different structure from the non-heat treatment portion by means of heat treatment applied to the bearing seat surface. The outer race hub heat treatment method enables forming the second heat treatment portion so as to be spaced apart from the first heat treatment portion, and thus damage to the annular wall part may be prevented.

Description

Axle device and outer race hub heat treatment method therefor

[0001] The present invention relates to an axle device and an outer race hub heat treatment method therefor.

[0002] In general, an axle device is a device that supports the weight of a vehicle through wheels and transmits power to the wheels, and a vehicle includes an axle device in a driving wheel or a non-driving wheel so that the vehicle can be driven.

[0003] Fig. 1 is a cross-sectional view illustrating a conventional axle device, and Fig. 2 is a cross-sectional view illustrating a process for heat treating a bearing seat surface and a stopper surface of an outer race hub in the axle device of Fig. 1.

[0004] Referring to FIGS. 1 and 2, a conventional axle device includes an inner race (10) that receives power from a powertrain and can rotate around a first axis, an outer race that accommodates the inner race (10) and can rotate around a second axis, an outer race hub (20) that is formed integrally with the outer race and has a hub that is connected to a wheel (W), a ball (30) that articulates and connects the inner race (10) and the outer race, and a bearing (40) that supports the outer race hub (20), and the bearing (40) includes an inner ring (41) that supports the outer race hub (20), an outer ring (42) that is supported on a vehicle body, and a rolling member (43) that is interposed between the inner ring (41) and the outer ring (42).

[0005] Here, the outer race hub (20) includes an annular wall portion (21) having an outer race groove (22) formed on the inner surface thereof to contact the ball (30) and a bearing seat surface (24) formed on the outer surface thereof to contact the inner surface of the inner ring (41) at a position radially overlapping the outer race groove (22), and the annular wall portion (21) further includes a stopper surface (26) that contacts the outer surface of the inner ring (41) and an orbital forming portion (28) that contacts the inner surface of the inner ring (41), and heat treatment is applied to the bearing seat surface (24) and the stopper surface (26) to prevent slip joint between the inner ring (41) and the outer race hub (20).

[0006] That is, as shown in FIG. 2, a coil (C1) for heating the bearing seat surface (24) and the stopper surface (26) is provided, and the coil (C1) has an axial width greater than half the axial length of the bearing seat surface (24), and the coil (C1) is positioned so as to simultaneously heat the bearing seat surface (24) and the stopper surface (26) and generate heat.

[0007] In addition, although not shown separately, heat treatment is applied to the outer race groove (22) to prevent wear due to contact with the ball (30).

[0008] Accordingly, the annular wall portion (21) further includes a non-heat-treated portion (21a), a first heat-treated portion (21b) having a different structure from the non-heat-treated portion (21a) due to heat treatment applied to the outer race groove (22), a second heat-treated portion (21c) having a different structure from the non-heat-treated portion (21a) due to heat treatment applied to the bearing seat surface (24), a third heat-treated portion (21d) having a different structure from the non-heat-treated portion (21a) due to heat treatment applied to the stopper surface (26), and a fourth heat-treated portion (21e) located at the boundary between the bearing seat surface (24) and the stopper surface (26) and having a different structure from the non-heat-treated portion (21a) due to heat treatment applied to the bearing seat surface (24) and heat treatment applied to the stopper surface (26).

[0009] However, in the conventional axle device and the heat treatment method for the outer race hub (20) therefor, there was a problem in that the first heat treatment section (21b) and the second heat treatment section (21c) overlapped, so that not only the surface of the annular wall section (21) but also the entire inside was hardened, resulting in a section lacking in toughness, and the annular wall was damaged.

[0010] Accordingly, the present invention aims to provide an axle device capable of preventing breakage and an outer race hub heat treatment method therefor.

[0011] The present invention, in order to achieve the above-mentioned object, comprises: an inner race rotatable about a first axis; an outer race accommodating the inner race and rotatable about a second axis; an outer race hub formed integrally with the outer race and a hub connected to a wheel; a ball connecting the inner race and the outer race in a slit-like manner; And a bearing having an inner ring supporting the outer race hub, an outer ring supported on a body, and a rolling member interposed between the inner ring and the outer ring; wherein the outer race hub includes an annular wall portion having an outer race groove formed on an inner surface thereof to contact the ball and a bearing seat surface formed on an outer surface thereof to contact the inner surface of the inner ring at a position radially overlapping the outer race groove, and wherein the annular wall portion includes a non-heat-treated portion, a first heat-treated portion having a different structure from the non-heat-treated portion due to a heat treatment applied to the outer race groove, and a second heat-treated portion having a different structure from the non-heat-treated portion due to a heat treatment applied to the bearing seat surface, and wherein the second heat-treated portion is formed to be spaced apart from the first heat-treated portion.

[0012] With respect to the outer race hub, if the wheel side is referred to as the outer side and the opposite side of the outer side is referred to as the inner side, the inner part of the second heat-treated portion may be formed such that the radial distance from the boundary between the second heat-treated portion and the non-heat-treated portion to the bearing seat surface decreases as it goes toward the inner side.

[0013] The inner portion of the second heat treatment section may be formed such that the rate of decrease in the radial distance from the boundary between the second heat treatment section and the non-heat treatment section to the bearing seat surface decreases as it goes inward.

[0014] The inner ring includes an outer inner ring disposed on the outer side and an inner inner ring disposed on the inner side, and the annular wall portion further includes a stopper surface that contacts the outer surface of the outer inner ring, and a boundary between the second heat treatment portion and the non-heat treatment portion meets the bearing seat surface at a position opposite to the inner peripheral surface of the inner inner ring, and a point where the bearing seat surface meets the boundary between the second heat treatment portion and the non-heat treatment portion is referred to as a second heat treatment portion inner end point, a point where the bearing seat surface meets the stopper surface is referred to as a second heat treatment portion outer end point, and an axial distance from the second heat treatment portion inner end point to the second heat treatment portion outer end point is referred to as a second heat treatment portion axial length, and the second heat treatment portion axial length can be formed to be included in a range of 1.3 to 2.0 times the axial length of the outer inner ring.

[0015] If the minimum value of the radial distance between the bearing seat surface and the outer race groove is defined as the minimum thickness of the annular wall portion, and the angle at which the ratio of the minimum thickness of the annular wall portion to the axial length of the second heat-treated portion becomes a tangent value is defined as a reference angle, then an acute angle between the boundary between the second heat-treated portion and the non-heat-treated portion in the inner portion of the second heat-treated portion and the bearing seat surface can be formed to be greater than 0 degrees and smaller than the reference angle.

[0016] The maximum quenching depth, which is the maximum value of the radial distance from the boundary between the second heat-treated section and the non-heat-treated section to the bearing seat surface, can be formed to be less than or equal to the minimum thickness of the annular wall section.

[0017] The above-mentioned annular wall portion may further include a third heat-treated portion having a different structure from the non-heat-treated portion due to heat treatment applied to the stopper surface, and a fourth heat-treated portion located at the boundary between the bearing seat surface and the stopper surface and having a different structure from the non-heat-treated portion due to heat treatment applied to the bearing seat surface and heat treatment applied to the stopper surface, and the fourth heat-treated portion may be formed such that a radial distance from the boundary between the fourth heat-treated portion and the non-heat-treated portion to a surface including the bearing seat surface increases as it goes inward.

[0018] The outer portion of the second heat treatment section is formed such that the radial distance from the boundary between the second heat treatment section and the non-heat treatment section to the bearing seat surface decreases as it goes outward, so that the boundary between the second heat treatment section and the non-heat treatment section can meet the boundary between the fourth heat treatment section and the non-heat treatment section.

[0019] And, the present invention provides a heat treatment method for an outer race hub for an axle device, comprising: a coil providing step of providing a coil for heating a bearing seat surface and a stopper surface of an outer race hub for the axle device, the coil having an axial width smaller than half the axial length of the bearing seat surface; a coil arranging step of arranging the coil at a position where the bearing seat surface and the stopper surface can be simultaneously heated; and a coil transfer heating step of transferring the coil in a direction away from the stopper surface along the axial direction of the bearing seat surface in a heated state.

[0020] In the above coil transfer heating step, the coil generates constant heat, and the transfer speed of the coil can increase as it moves away from the stopper face along the axial direction of the bearing seat face.

[0021] An axle device and an outer race hub heat treatment method therefor according to the present invention are characterized in that the axle device includes an inner race, an outer race hub, a ball that connects the inner race and the outer race hub in a slit-like manner, and a bearing that supports the outer race hub, wherein the outer race hub includes an annular wall portion having an outer race groove formed on an inner surface thereof to be in contact with the ball and a bearing seat surface formed on an outer surface thereof to be in contact with the inner surface of the bearing at a position radially overlapping the outer race groove, wherein the annular wall portion includes a non-heat-treated portion, a first heat-treated portion having a different structure from the non-heat-treated portion due to heat treatment applied to the outer race groove, and a second heat-treated portion having a different structure from the non-heat-treated portion due to heat treatment applied to the bearing seat surface, and since the second heat-treated portion is formed to be spaced apart from the first heat-treated portion by the outer race hub heat treatment method, breakage of the annular wall portion can be prevented.

[0022] Fig. 1 is a cross-sectional view showing a conventional axle device;

[0023] Fig. 2 is a cross-sectional view showing a process for heat treating the bearing seat surface and stopper surface of the outer race hub in the axle device of Fig. 1.

[0024] Figure 3 is a cross-sectional view showing an axle device according to one embodiment of the present invention;

[0025] Fig. 4 is a cross-sectional view illustrating a process for heat treating the bearing seat surface and stopper surface of the outer race hub in the axle device of Fig. 3.

[0026] Hereinafter, the axle device according to the present invention and the outer race hub heat treatment method therefor will be described in detail with reference to the attached drawings.

[0027] FIG. 3 is a cross-sectional view illustrating an axle device according to one embodiment of the present invention, and FIG. 4 is a cross-sectional view illustrating a process for heat-treating a bearing seat surface and a stopper surface of an outer race hub in the axle device of FIG. 3.

[0028] Referring to FIGS. 3 and 4, an axle device according to one embodiment of the present invention may include an inner race (100) that receives power from a powertrain and can rotate around a first axis, an outer race that accommodates the inner race (100) and can rotate around a second axis, an outer race hub (200) that is formed integrally with the outer race and has a hub that is connected to a wheel (W), a ball (300) that articulates and connects the inner race (100) and the outer race, and a bearing (400) that supports the outer race hub (200).

[0029] The above inner race (100) can be formed in a circular shape.

[0030] And, a driving shaft can be inserted and fastened into the inner portion of the inner race (100).

[0031] In addition, an inner race groove that comes into contact with the ball (300) can be formed on the outer periphery of the inner race (100).

[0032] The above outer race hub (200) can be formed in a circular shape.

[0033] And, with respect to the outer race hub (200), if the wheel (W) side (left side in FIG. 3) is referred to as the outer side and the opposite side (right side in FIG. 3) is referred to as the inner side, the outer race may be formed at the inner end of the outer race hub (200), and the hub may be formed at the outer end of the outer race hub (200).

[0034] The bearing (400) includes a bearing (400) having an inner ring (410) supporting the outer race hub (200), an outer ring (420) supported on a body, and a rolling member (430) interposed between the inner ring (410) and the outer ring (420), and the inner ring (410) may include an outer inner ring (412) disposed on the outer side and an inner inner ring (414) disposed on the inner side.

[0035] Here, the outer race hub (200) may include an annular wall portion (210) having an outer race groove (212) formed on the inner surface to contact the ball (300) and a bearing seat surface (214) formed on the outer surface to contact the inner surface of the inner ring (410) at a position radially overlapping the outer race groove (212).

[0036] In addition, the annular wall portion (210) further includes a stopper surface (216) that contacts the outer surface of the outer inner ring (412) and an orbital forming portion (218) that contacts the inner surface of the inner inner ring (414). In order to prevent slip joint between the inner ring (410) and the outer race hub (200), heat treatment may be applied to the bearing seat surface (214) and the stopper surface (216).

[0037] In addition, heat treatment may be applied to the outer race groove (212) to prevent wear due to contact with the ball (300).

[0038] Accordingly, the annular wall portion (210) is formed by a non-heat-treated portion (210a), a first heat-treated portion (210b) having a different structure from the non-heat-treated portion (210a) due to heat treatment applied to the outer race groove (212), a second heat-treated portion (210c) having a different structure from the non-heat-treated portion (210a) due to heat treatment applied to the bearing seat surface (214), a third heat-treated portion (210d) having a different structure from the non-heat-treated portion (210a) due to heat treatment applied to the stopper surface (216), and a fourth heat-treated portion (210d) located at the boundary between the bearing seat surface (214) and the stopper surface (216) and having a different structure from the non-heat-treated portion (210a) due to heat treatment applied to the bearing seat surface (214) and heat treatment applied to the stopper surface (216). It may further include a heat treatment section (210e).

[0039] Here, the heat treatment of the bearing seat surface (214) and the stopper surface (216) can be performed according to a coil providing step in which a coil (C2) for heating the bearing seat surface (214) and the stopper surface (216) is provided, as shown in FIG. 4, and the coil (C2) having an axial width smaller than half the axial length of the bearing seat surface (214) is provided, a coil arranging step in which the coil (C2) is arranged at a position where it can simultaneously heat the bearing seat surface (214) and the stopper surface (216), and a coil transfer heating step in which the coil (C2) is transferred in a direction away from the stopper surface (216) along the axial direction of the bearing seat surface (214) while generating heat.

[0040] In particular, in the coil transfer heating step, the coil (C2) generates constant heat and the transfer speed of the coil (C2) can increase as it moves away from the stopper face (216) along the axial direction of the bearing seat face (214).

[0041] Accordingly, the inner portion of the second heat treatment portion (210c) is formed so that the radial distance from the boundary between the second heat treatment portion (210c) and the non-heat treatment portion (210a) to the bearing seat surface (214) decreases as it goes inward, so that the second heat treatment portion (210c) can be formed to be spaced apart from the first heat treatment portion (210b). That is, the non-heat treatment portion (210a) can be interposed between the second heat treatment portion (210c) and the first heat treatment portion (210b). As a result, not only the surface layer of the annular wall portion (210) but also the entire inside is prevented from being hardened, so that damage to the annular wall portion (210) can be prevented.

[0042] And, the fourth heat treatment section (210e) is formed so that the radial distance from the boundary between the fourth heat treatment section (210e) and the non-heat treatment section (210a) to the surface including the bearing seat surface (214) increases as it goes inward, and the outer portion of the second heat treatment section (210c) is formed so that the radial distance from the boundary between the second heat treatment section (210c) and the non-heat treatment section (210a) to the bearing seat surface (214) decreases as it goes outward, so that the boundary between the second heat treatment section (210c) and the non-heat treatment section (210a) can meet the boundary between the fourth heat treatment section (210e) and the non-heat treatment section (210a). Accordingly, the occurrence of cracks between the second heat-treated portion (210c) and the fourth heat-treated portion (210e) can be suppressed, and the distance from the edge between the bearing seat surface (214) and the stopper surface (216) to the boundary between the fourth heat-treated portion (210e) and the non-heat-treated portion (210a) can be secured to a predetermined value or more, thereby suppressing the occurrence of cracks at the edge between the bearing seat surface (214) and the stopper surface (216). In addition, the maximum quenching depth (t), which is the maximum value of the radial distance from the boundary between the second heat-treated portion (210c) and the non-heat-treated portion (210a) to the bearing (400) seat surface, can be made smaller than or equal to the minimum thickness (T) of the annular wall portion, which is the minimum value of the radial distance between the bearing seat surface (214) and the outer race groove (212), so that both rigidity and toughness can be increased.

[0043] In addition, the inner portion of the second heat treatment portion (210c) may be formed such that the rate of decrease in the radial distance from the boundary between the second heat treatment portion (210c) and the non-heat treatment portion (210a) to the bearing seat surface (214) decreases as it goes inward. Accordingly, as the second heat treatment portion (210c) is spaced apart from the first heat treatment portion (210b), the slip joint suppression effect between the inner ring (410) and the outer race hub (200) can be increased.

[0044] Specifically, as described above, the inner portion of the second heat-treated portion (210c) is formed such that the radial distance from the boundary between the second heat-treated portion (210c) and the non-heat-treated portion (210a) to the bearing seat surface (214) decreases as it goes inward, so that the boundary between the second heat-treated portion (210c) and the non-heat-treated portion (210a) can meet the bearing seat surface (214) at a position facing the inner circumferential surface of the inner inner ring (414). At this time, if the point where the bearing (400) seat surface meets the boundary between the second heat treatment section (210c) and the non-heat treatment section (210a) is referred to as the second heat treatment section inner end point (D), the point where the bearing seat surface (214) meets the stopper surface (216) is referred to as the second heat treatment section outer end point (B), and the axial distance from the second heat treatment section inner end point (D) to the second heat treatment section outer end point (B) is referred to as the second heat treatment section axial length (A), it may be preferable that the second heat treatment section axial length (A) be formed to be included in a range of 1.3 to 2.0 times the axial length (I) of the outer inner ring (412). When the axial length (A) of the second heat treatment section is less than 1.3 times the axial length (I) of the outer inner ring (412), the slip joint between the inner ring (410) and the outer race hub (200) is not sufficiently suppressed, and when the axial length (A) of the second heat treatment section is greater than twice the axial length (I) of the outer inner ring (412), the second heat treatment section (210c) may overlap the first heat treatment section (210b).

[0045] In consideration of this, if the angle at which the ratio (T / A) of the minimum thickness (T) of the annular wall portion to the axial length (A) of the second heat treatment portion becomes a tangent value is a reference angle, then an acute angle between the boundary between the second heat treatment portion (210c) and the non-heat treatment portion (210a) in the inner portion of the second heat treatment portion (210c) and the seat surface of the bearing (400) may be formed to be greater than 0 degrees and smaller than the reference angle. In addition, the boundary between the second heat treatment portion (210c) and the non-heat treatment portion (210a) in the inner portion of the second heat treatment portion (210c) may extend toward a reference point (C), which is a point at which a first virtual line passing axially through the maximum quenching point of the second heat treatment portion having the maximum quenching depth (t) intersects a second virtual line passing radially through the maximum quenching point of the second heat treatment portion.

[0046] However, when the inner portion of the second heat treatment portion (210c) is formed so that the rate of decrease in the radial distance from the boundary between the second heat treatment portion (210c) and the non-heat treatment portion (210a) to the bearing seat surface (214) decreases as it goes inward, the axial length (A) of the second heat treatment portion (210c) increases within a range in which the second heat treatment portion (210c) does not overlap the first heat treatment portion (210b), thereby suppressing damage to the annular wall portion (210) and increasing the slip joint suppression effect between the inner ring (410) and the outer race hub (200).

Claims

1. Inner race rotatable around the first axis; An outer race hub that accommodates the inner race and is rotatable about a second axis, and a hub that is integrally formed with the outer race and is connected to the wheel; A ball that connects the inner race and the outer race so that they can be cut; and A bearing having an inner ring supporting the outer race hub, an outer ring supported on the body, and a rolling member interposed between the inner ring and the outer ring; The above outer race hub includes an annular wall portion having an outer race groove formed on the inner surface that contacts the ball and a bearing seat surface formed on the outer surface that contacts the inner surface of the inner ring at a position radially overlapping the outer race groove. The above annular wall portion includes a non-heat-treated portion, a first heat-treated portion having a different structure from the non-heat-treated portion due to heat treatment applied to the outer race groove, and a second heat-treated portion having a different structure from the non-heat-treated portion due to heat treatment applied to the bearing seat surface. The second heat treatment section is an axle device formed to be spaced apart from the first heat treatment section.

2. In paragraph 1, An axle device in which, with respect to the outer race hub, the wheel side is referred to as the outer side and the side opposite to the outer side is referred to as the inner side, the inner portion of the second heat-treated portion is formed such that the radial distance from the boundary between the second heat-treated portion and the non-heat-treated portion to the bearing seat surface decreases as it goes toward the inner portion.

3. In paragraph 2, An axle device in which the inner portion of the second heat treatment section is formed such that the rate of decrease in the radial distance from the boundary between the second heat treatment section and the non-heat treatment section to the bearing seat surface decreases as it goes toward the inner portion.

4. In paragraph 2, The above inner ring includes an outer inner ring arranged on the outside and an inner inner ring arranged on the inside, The above annular wall portion further includes a stopper surface that contacts the outer surface of the outer inner ring, An axle device wherein a boundary between the second heat treatment section and the non-heat treatment section meets the bearing seat surface at a position facing the inner circumferential surface of the inner inner ring, a point where the bearing seat surface meets the boundary between the second heat treatment section and the non-heat treatment section is referred to as a second heat treatment section inner endpoint, a point where the bearing seat surface meets the stopper surface is referred to as a second heat treatment section outer endpoint, and an axial distance from the second heat treatment section inner endpoint to the second heat treatment section outer endpoint is referred to as a second heat treatment section axial length, and the axial length of the second heat treatment section is formed to be included in a range of 1.3 to 2.0 times the axial length of the outer inner ring.

5. In paragraph 4, An axle device in which an acute angle between a boundary between the second heat-treated portion and the non-heat-treated portion in an inner portion of the second heat-treated portion and the bearing seat surface is formed to be greater than 0 degrees and less than the reference angle, wherein the minimum value of the radial distance between the bearing seat surface and the outer race groove is defined as the minimum thickness of the annular wall portion, and an angle at which a ratio of the minimum thickness of the annular wall portion to the axial length of the second heat-treated portion becomes a tangent value is defined as a reference angle.

6. In paragraph 5, An axle device in which the maximum quenching depth, which is the maximum value of the radial distance from the boundary between the second heat-treated section and the non-heat-treated section to the bearing seat surface, is formed to be less than or equal to the minimum thickness of the annular wall section.

7. In paragraph 4, The above annular wall portion further includes a third heat-treated portion having a different structure from the non-heat-treated portion due to the heat treatment applied to the stopper surface, and a fourth heat-treated portion located at the boundary between the bearing seat surface and the stopper surface and having a different structure from the non-heat-treated portion due to the heat treatment applied to the bearing seat surface and the heat treatment applied to the stopper surface. An axle device in which the fourth heat treatment section is formed such that the radial distance from the boundary between the fourth heat treatment section and the non-heat treatment section to the surface including the bearing seat surface increases as it goes toward the inside.

8. In paragraph 7, An axle device in which the outer portion of the second heat treatment section is formed such that the radial distance from the boundary between the second heat treatment section and the non-heat treatment section to the bearing seat surface decreases as it goes toward the outer portion, so that the boundary between the second heat treatment section and the non-heat treatment section meets the boundary between the fourth heat treatment section and the non-heat treatment section.

9. A coil-providing step comprising: providing a coil for heating a bearing seat surface and a stopper surface of an outer race hub for an axle device according to any one of claims 1 to 8, wherein the coil has an axial width smaller than half the axial length of the bearing seat surface; A coil arrangement step for arranging the coil in a position where the bearing seat surface and the stopper surface can be heated simultaneously; and An outer race hub heat treatment method for an axle device, comprising a coil transfer heating step of transferring the coil away from the stopper surface along the axial direction of the bearing seat surface while heating the coil.

10. In paragraph 9, An outer race hub heat treatment method for an axle device, wherein the coil generates constant heat in the coil transfer heating step and the transfer speed of the coil increases as it moves away from the stopper face along the axial direction of the bearing seat face.

Images