Method for rectification of a sealing surface

Abstract

The invention relates to a method for grinding a portion of a component part having a bearing surface (1a) on which a sealing lip (2) is intended to make frictional contact, said grinding being carried out by means of a grinding wheel having an abrasive cylindrical surface which has been previously dressed by a dressing wheel having a cylindrical dressing surface, said method comprising: making annular grooves (8) on the dressing surface in order to form a surface undulation extending axially along a period P and radially over a depth p; dressing said undulation on the abrasive surface of the grinding wheel; grinding the portion of the component (3) by forming said undulation at least on the sealing bearing surface (1a). Figure 3

Description

Title of the invention: Method for rectifying a sealing surface

[0001] The invention relates to a method for grinding a portion of a component of a mechanical part having a bearing surface on which a sealing lip is intended to come into contact by rubbing.

[0002] It applies in particular to a bearing housing in which at least one side of the bearing space is equipped with a seal in which a lip is in contact rubbing on a ground surface.

[0003] According to a particular application, the invention makes it possible to seal at least one side of the bearing space of a motor vehicle bearing, in particular a wheel bearing.

[0004] To prevent on the one hand the leakage of the lubricant present in the bearing space, and on the other hand the contamination of said space with external pollutants, the use of sealing gaskets having a lip attached to one component of the bearing to come into contact by rubbing on a cylindrical surface of the other component is known, in particular by placing a lubricant at the interface between said lip and said surface.

[0005] In the applications envisaged, the sealing constraints are severe, particularly with regard to the environments to which the seals are subjected, which requires increasing the torque exerted by the lip on the friction surface.

[0006] However, in addition to the negative impact on the energy required to rotate the bearing, a high torque causes premature wear of the lip, particularly under the effect of the induced temperature increase.

[0007] There is therefore a need to improve the dynamic behavior of a sealing lip on a friction surface, so as, by optimizing the relationship between the sealing conferred and the induced torque, to limit the wear of said lip.

[0008] To this end, and according to a first aspect, the invention proposes a method for grinding a portion of a component of a mechanical part having a bearing surface on which a sealing lip is intended to make contact by friction, said grinding being carried out by means of a grinding wheel having an abrasive cylindrical surface which has been previously dressed by a dressing wheel having a cylindrical dressing surface, said method comprising: - to create annular striations on the cylindrical dressing surface in order to form a surface undulation extending axially along a period P and radially over a depth p; - the straightening of said undulation on the abrasive surface of the grinding wheel; - the rectification of the portion of the organ by forming said undulation at least on the sealing surface.

[0009] According to a second aspect, the invention proposes a bearing comprising a fixed member, a rotating member and rolling bodies arranged in a bearing space formed between said members to allow their relative rotation, at least one side of the bearing space being equipped with a seal integral with a member of the bearing, said seal having a contact lip rubbing on a cylindrical bearing surface of the other member, said bearing surface having been ground by implementing a process according to the first aspect to present a surface undulation extending axially over a period P and radially over a depth p.

[0010] Other objects and advantages of the invention will become apparent from the following description, made with reference to the accompanying figures, in which:

[0011] [Fig. 1] is a schematic representation of the implementation of a rectification process according to the invention;

[0012] [Fig.2] is a schematic longitudinal sectional representation showing the surface dressing of a wheel usable in a grinding process according to the invention;

[0013] [Fig.3] is a schematic representation of the rubbing contact between a lip sealing and a bearing surface according to the invention,

[0014] [Fig.3a] being an enlarged view of said span.

[0015] In relation to these figures, a method for rectifying a portion 1 of an element of a mechanical component having a bearing surface la on which a sealing lip 2 is intended to come into contact by rubbing is described.

[0016] Fig. 1 represents the rotating member 3 of a wheel bearing comprising a fixed member and rolling bodies which are arranged in a rolling space formed between said members to allow their relative rotation.

[0017] At least one side of the bearing space is equipped with a seal integral with a bearing component, said seal having at least one lip 2 in contact rubbing on at least one cylindrical surface la of the other component 3.

[0018] According to one embodiment, the sealing joint has a rigid annular reinforcement for association with a component, for example the fixed component and, associated with said reinforcement, a flexible sealing element which can be made of elastomeric material, in particular a butadiene nitrile copolymer (NBR), possibly mechanically reinforced by fillers such as carbon black, hydrogenated NBR (HNBR), fluoropolymer or polyacrylate.

[0019] In particular, the sealing element can be associated by overmolding onto the frame and have a free lip 2 which, during the rotation of the bearing, is in contact rubbing on a bearing surface la of the member 3.

[0020] To optimize the sealing of the friction of the lip 2 on the bearing surface while limiting the induced torque, the portion 1 of the member 3 is ground using a grinding wheel 4 having an abrasive cylindrical surface 5. In addition, the portion 1 of the member 3 can be formed during grinding, in particular to the desired geometry.

[0021] Prior to its use, the grinding wheel 4 is dressed by a dresser 6 having a cylindrical dressing surface 7 which notably serves to refresh the abrasive surface 5 to optimize grinding performance. In particular, dressing can be carried out periodically, especially after a certain number of grinding cycles, so as to maintain grinding performance over time.

[0022] The rectification process involves making annular grooves 8 on the dressing surface 7, in order to form a surface undulation extending axially along a period P and radially over a depth p.

[0023] In particular, the positioning terms in space are defined with respect to the axis of rotation RI, R2, R3 of the different components (bearing, grinding wheel), in particular the terms "annular" or "cylindrical" are defined in relation to a closed curve of revolution around said axis.

[0024] Next, the grinding process involves dressing the corrugation on the abrasive surface 5 of the grinding wheel 4, then grinding the portion 1 of the member 3 by forming said corrugation at least on the sealing surface la.

[0025] In particular in relation to the presence of a lubricant 9 at the interface between the lip 2 and the bearing la, the applicant has observed that the corrugation allows a significant reduction in the rotational torque while preserving the sealing conferred, in particular due to the filling of the corrugation with said lubricant.

[0026] In particular, the reduction in torque is notable when the undulation is made with striations 8 which extend annularly in parallel with each other, that is to say in particular by not being helical.

[0027] Advantageously, the undulation is carried out with a period P which is greater than the depth p, in particular with a period P which is between 5 and 50 times, in particular between 3 and 10 times, the depth p.

[0028] According to numerical examples, the depth p is between 5 and 200 qm, the period P being between 100 and 800 qm.

[0029] In relation to the figures, the undulation of the dressing surface 7, and therefore that of the friction area la, is achieved with grooves 8 connected by bumps 10, the period P being measured between two bumps 10 or between two adjacent grooves 8.

[0030] In particular, the striations 8 and the bumps 10 extend axially along a radius respectively Rs, Rb which can advantageously be equal to + / - 30%, in particular to + / - 10%.

[0031] Furthermore, the sealing area has a length L on which the sealing lip 2 is intended to come into frictional contact, the ratio of said length L to the period P (L / P) is at least equal to 2, in particular being between 3 and 5. Thus, the lip 2 comes into frictional contact on at least two bumps 10 to optimize the sealing conferred.

[0032] In relation to [Fig. 2], the dressing surface 7 has grains 11 of abrasive material, in particular in the form of diamonds. The grains 11 are distributed to form radially projecting annular rows 12 which are separated by annular striations 8 so as to form the undulation of the dressing surface 7.

[0033] According to one embodiment, the roller 6 is obtained by molding the grains 11 onto the dressing surface 7, in particular by presenting a molded die 13 on the surface of which the grains 11 are arranged. The molding is carried out against a cavity on which the grooves 8 are formed in negative.

[0034] According to another embodiment, the annular rows 12 are formed by grains 11 whose size is greater than the size of the grains 11 arranged in the grooves 8.

Claims

1.

2.

3.

4.

5.

6.

7.

8. Demands A method for grinding a portion (1) of a component (3) of a mechanical part having a bearing surface (la) on which a sealing lip (2) is intended to make contact by friction, said grinding being carried out by means of a grinding wheel (4) having an abrasive cylindrical surface (5) which has been previously dressed by a dressing wheel (6) having a cylindrical dressing surface (7), said method comprising: - to create annular striations (8) on the dressing surface (7) in order to form a surface undulation extending axially along a period P and radially over a depth p; - the straightening of said undulation on the abrasive surface (5) of the grinding wheel (4); - the rectification of the portion (1) of the organ (3) by forming at least one said undulation on the sealing surface (la). A method according to claim 1, characterized in that the undulation is achieved with a period P which is greater than the depth p. A method according to claim 2, characterized in that the period P is between 5 and 50 times the depth p. A method according to any one of claims 1 to 3, characterized in that the undulation is achieved with striations (8) which extend annularly in parallel with each other. A method according to any one of claims 1 to 4, characterized in that the undulation is achieved with striations (8) which are connected by bumps (10). Method according to claim 5, characterized in that the striations (8) and the bumps (10) extend axially along a radius respectively Rs, Rb. Method according to claim 6, characterized in that the radii Rs and Rb are equal to + / - 30%. A method according to any one of claims 1 to 7, characterized in that the sealing surface (la) has a length L on which the sealing lip (2) is intended to come into contact by rubbing, the ratio of said length L to the period P being at least equal to 2.

9. A method according to any one of claims 1 to 8, characterized in that the depth p is between 5 and 200 sqm.

10. A method according to any one of claims 1 to 9, characterized in that the dressing surface (7) has grains (11) of abrasive material, said grains being distributed to form radially projecting annular rows (12) which are separated by annular striations (8) so as to form the undulation of the dressing surface (7).

11. Method according to claim 10, characterized in that the wheel (6) is obtained by molding the grains (11) on the dressing surface (7), said molding being carried out against a cavity on which the grooves (8) are made in negative.

12. A method according to claim 10, characterized in that the annular rows (12) are formed by grains (11) whose size is greater than the size of the grains (11) arranged in the grooves (8).

13. A method according to any one of claims 1 to 12, characterized in that it provides for forming the portion (1) of the component (3) during grinding.

14. A rolling bearing comprising a fixed member, a rotating member (3) and rolling bodies arranged in a rolling space formed between said members to allow their relative rotation, at least one side of the rolling space being equipped with a seal integral with a member of the bearing, said seal having a lip (2) in contact rubbing against a cylindrical bearing surface (la) of the other member (3), said bearing surface having been ground by implementation of a method according to any one of claims 1 to 13 to have a surface undulation extending axially over a period P and radially over a depth p.

15. Bearing according to claim 14, characterized in that a lubricant (9) is disposed at the interface between the lip (2) and the bearing surface (la).

Images