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Title:
A METHOD AND AN APPARATUS FOR POLISHING BY PRESSURE OF A WHEEL ELEMENT
Document Type and Number:
WIPO Patent Application WO/2021/004623
Kind Code:
A1
Abstract:
A method for manufacturing a wheel element (1 ) for a vehicle is described. The method comprises polishing by pressure of at least one predetermined surface portion (3) extending on one side of the wheel element (1) by means of a polishing tool (5) in order to increase the fatigue strength of the wheel element (1). The method comprises the steps of: providing a rotation of the wheel element (1) around a rotational axis (7) of the wheel element (1) and pressing the polishing tool (3) against the at least one predetermined surface portion (5) of the wheel element (1) during the rotation of the wheel element (1). An apparatus (15) for manufacturing a wheel element (1 ) and a wheel element (1) are also described.

Inventors:
JOHANSSON PÄR (SE)
FYHRLUND MARCUS (SE)
AUGUSTSSON KENT (SE)
Application Number:
PCT/EP2019/068328
Publication Date:
January 14, 2021
Filing Date:
July 09, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
AUTOMOTIVE COMPONENTS FLOBY AB (SE)
International Classes:
B21K1/28; B23P15/00; B24B39/00; B60B3/06; C21D7/08; C22F1/04
Domestic Patent References:
WO1998041360A11998-09-24
WO2005102737A12005-11-03
Foreign References:
US5722165A1998-03-03
US5722165A1998-03-03
Attorney, Agent or Firm:
BJERKÉNS PATENTBYRÅ KB (STOCKHOLM) (SE)
Download PDF:
Claims:
Claims

1. A method for manufacturing a wheel element (1 ) for a vehicle, wherein the method comprises polishing by pressure of at least one predetermined surface portion (3) extending on one side of said wheel element (1 ) by means of a polishing tool (5) in order to increase the fatigue strength of said wheel element (1 ),

characterized in that the method comprises the steps of:

providing a rotation of the wheel element (1 ) around a rotational axis (7) of said wheel element (1 ) and

pressing said polishing tool (5) against said at least one predetermined surface portion (3) of the wheel element (1 ) during said rotation of the wheel element (1 ). 2. The method according to claim 1 , wherein said pressing comprises an

intermittent engagement of said polishing tool (5) with the at least one predetermined surface portion (3) due to said rotation of the wheel element (1 )· 3. The method according to claim 1 or 2, wherein said polishing tool (5) is

arranged to roll on said at least one predetermined surface portion (3).

4. The method according to any of claims 1 to 3, wherein said polishing tool (5) comprises a ball (9).

5. The method according to any of claims 1 to 4, wherein said wheel element (1 ) comprises several of the predetermined surface portions (3) arranged at a distance from each other at a common radius (r) of the wheel element (1 ). 6. The method according to claim 5, wherein the predetermined surface

portions (3) are separated from each other by respective intermediate portions (11 ) and wherein the predetermined surface portions (3) are elevated in relation to said intermediate portions (11 ). 7. The method according to any of claims 1 to 6 wherein each of said predetermined surface portions (3) is arranged adjacent to a bolt opening (13) of said wheel element (1 ). 8. The method according to any of claims 1 to 7, wherein said wheel element

(1 ) comprises a wheel hub.

9. An apparatus (15) for manufacturing a wheel element (1 ) for a vehicle, wherein the apparatus (15) comprises a polishing tool (5) configured for polishing by pressure at least one predetermined surface portion (3) extending on one side of said wheel element (1 ) in order to increase the fatigue strength of said wheel element (1 ),

characterized in that the apparatus (15) comprises:

- a rotation device (17) arranged to provide a rotation of the wheel

element (1 ) around a rotational axis (7) of said wheel element (1 ) and

- a pressing device (19) arranged for pressing said polishing tool (5)

against said at least one predetermined surface portion (3) of the wheel element (1 ) during said rotation of the wheel element (1 ). 10. The apparatus (15) according to claim 9, wherein said pressing device (19) is arranged to achieve an intermittent engagement of said polishing tool (5) with the at least one predetermined surface portion (3) due to said rotation of the wheel element (1 ). 11.The apparatus (15) according to claim 9 or 10, wherein said polishing tool

(5) is arranged to roll on said at least one predetermined surface portion (3).

12. The apparatus (15) according to any of claims 9 to 11 , wherein said

polishing tool (5) comprises a ball (9).

13. The apparatus (15) according to any of claims 9 to 12, wherein said wheel element (1 ) comprises several of the predetermined surface portions (3) arranged at a distance from each other at a common radius (r) of the wheel element (1 ). 14. The apparatus (15) according to claim 13, wherein the predetermined surface portions (3) are separated from each other by respective

intermediate portions (11 ) and wherein the predetermined surface portions (3) are elevated in relation to said intermediate portions (11 ).

15. The apparatus (15) according to any of claims 9 to 14, wherein each of said predetermined surface portions (3) is arranged adjacent to a bolt opening (13) of said wheel element (1 ). 16. The apparatus (15) according to any of claims 9 to 15, wherein said wheel element (1 ) comprises a wheel hub.

17. A wheel element (1 ) for a vehicle, wherein the wheel element (1 )

comprises at least one predetermined surface portion (3) extending on one side of said wheel element (1 )

characterized in that the at least one predetermined surface portion (3) has been polished by pressure during a rotation of the wheel element (1 ) around a rotational axis (7) of said wheel element (1 ) while a polishing tool (5) has been pressed against said at least one predetermined surface portion (3) of the wheel element (1 ) during said rotation of the wheel element (1 ).

18. The wheel element (1 ) according to claim 17, wherein said wheel element (1 ) comprises several of the predetermined surface portions (3) arranged at a distance from each other at a common radius (r) of the wheel element (1 ).

19. The wheel element (1 ) according to claim 17, wherein the predetermined surface portions (3) are separated from each other by respective

intermediate portions (11 ) and wherein the predetermined surface portions (3) are elevated in relation to said intermediate portions (11 ).

20. The wheel element (1 ) according to any of claims 17 to 19, wherein each of said predetermined surface portions (3) is arranged adjacent to a bolt opening (13) of said wheel element (1 ).

21. The wheel element (1 ) according to any of claims 17 to 20, wherein said wheel element (1 ) comprises a wheel hub.

Description:
A method and an apparatus for polishing by pressure of a wheel element

BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention relates to a method and to an apparatus for polishing by pressure of a wheel element. The invention relates also to a wheel element that has been polished by pressure.

Conventionally, wheel elements such as cast wheels or wheel hubs are manufactured by casting followed by subsequent after treatment processes that are performed in order to achieve desired form and characteristics of the wheel elements.

After the finished manufacturing process of a wheel element, there may exist some remaining tension stresses at some areas of the wheel element which may cause cracks in the wheel element during use of the wheel element.

Efforts have been made to reduce the tension stress at some areas of wheel elements. US5722165A is an example of a method for producing a cast aluminium wheel where a roller-burnishing process is used in order to improve the fatigue strength of the cast aluminium wheel. Although, the method works well, there is a need of an improved method for manufacturing of a wheel element.

Therefore, the invention aims at an improvement regarding the method and the apparatus for manufacturing a wheel element for a vehicle using polishing by pressure. The improvement considers, inter alia, efficiency of the process of polishing by pressure in order to reduce the tension stress at certain areas of a wheel element.

It is therefore desirable to provide an improved method and an improved apparatus for manufacturing a wheel element using polishing by pressure. Further, it is desirable to provide an improved wheel element with improved characteristics regarding, inter alia, the fatigue strength of the wheel element. SUMMARY OF THE INVENTION

The object of the present invention is to provide an improved method and an improved apparatus for manufacturing a wheel element for a vehicle using polishing by pressure. Further, the object of the invention is to provide an improved wheel element.

The object is achieved by the method defined in claim 1 and by the apparatus defined in claim 9. The object is also achieved by the wheel element defined in claim 17.

Thus, the above mentioned object is achieved by a method for manufacturing a wheel element for a vehicle. The method comprises polishing by pressure of at least one predetermined surface portion extending on one side of the wheel element by means of a polishing tool in order to increase the fatigue strength of the wheel element. The process of polishing by pressure can also be called burnishing. The method comprises the steps of: providing a rotation of the wheel element around a rotational axis of the wheel element and pressing the polishing tool against the at least one predetermined surface portion of the wheel element during the rotation of the wheel element.

Thus, the position of the at least one predetermined surface portion can be changed in relation to the polishing tool by rotating the wheel element around the rotational axis of the wheel element. Thereby, the at least one predetermined surface portion of the wheel element can be polished by pressure in an efficient manner thanks to the relative movement of the at least one predetermined surface portion in relation to the polishing tool, which relative movement is achieved, inter alia, by the rotational movement of the wheel element.

Further, the polishing tool is pressed against the at least one predetermined surface portion of the wheel element during the rotation of the wheel element. To achieve a polishing effect of the at least one predetermined surface portion, i.e. a plastic deformation of the at least one predetermined surface portion, the polishing tool needs to have contact with the at least one predetermined surface portion and needs to act with a pressure force on the surface of the at least one predetermined surface portion. The polishing tool is pressed against the at least one predetermined surface portion by a movement of the polishing tool towards the at least one predetermined surface portion to achieve the plastic deformation of the at least one predetermined surface portion. The plastic deformation contributes to reduction of the tension stresses at the at least one predetermined surface portion.

Consequently, by pressing the polishing tool against the at least one predetermined surface portion during rotation of the wheel element the at least one predetermined surface portion is polished by pressure in an efficient way.

Thereby the above mentioned object is achieved.

According to an embodiment the pressing comprises an intermittent

engagement of the polishing tool with the at least one predetermined surface portion due to the rotation of the wheel element.

The polishing tool has a contact with the at least one

predetermined surface portion during a part of a rotational circle of the wheel element. Thus, the polishing tool has no contact with the at least one

predetermined surface portion during another part of the rotational circle of the wheel element. Thereby, regulation of the position of the polishing tool in relation to the wheel element can be improved and can be facilitated because the intermittent engagement of the polishing tool with the at least one predetermined surface portion.

Consequently, the intermittent, i.e. discontinuous, engagement of the polishing tool with the at least one predetermined surface portion

contributes to yet improved method for manufacturing of a wheel element for a vehicle.

According to an embodiment the polishing tool is arranged to roll on the at least one predetermined surface portion. Thus, the polishing tool can move along the at least one predetermined surface portion by rolling on the at least one predetermined surface portion, which rolling comprises gliding and rotation of the polishing tool on the at least one predetermined surface portion. According to an embodiment the polishing tool comprises a ball. The curvature of the boll facilitates the process of polishing by pressure of the at least one predetermined surface portion. Thereby, it is advantageous to use a boll in a polishing by pressure process.

According to an embodiment the wheel element comprises several of the predetermined surface portions arranged at a distance from each other at a common radius of the wheel element. The several of the predetermined surface portions are separated from each other and are arranged at a common distance from a center of the wheel element. Thereby, several of the predetermined surface portions can be polished by pressure during rotation of the wheel element. Thus, the process of polishing by pressure is yet improved because several of the predetermined surface portions can by polished effectively at the time the wheel element is rotating around the rotational axis.

According to an embodiment the predetermined surface portions are separated from each other by respective intermediate portions, wherein the predetermined surface portions are elevated in relation to the intermediate portions. The predetermined surface portions may thus be arranged at a distance from each other with a respective intermediate portion arranged between two predetermined surface portions. The predetermined surface portions may be arranged at a higher level comparing to the intermediate portions which facilitates the contact between the polishing tool and the predetermined surface portions.

According to an embodiment each of the predetermined surface portions are arranged adjacent to a bolt opening of the wheel element. Thereby, possible tension stresses at an area adjacent to a bolt opening can be at least reduced by applying polishing by pressure using the polishing tool that is pressed against each of the predetermined surface portions. According to an embodiment the wheel element comprises a wheel hub.

Consequently, possible tension stresses in a wheel hub can be at least reduced by applying polishing by pressure using the polishing tool that is pressed against each of the predetermined surface portions of the wheel hub. The above mentioned object is also achieved by an apparatus comprising a polishing tool configured for polishing by pressure of at least one

predetermined surface portion extending on one side of a wheel element in order to increase the fatigue strength of the wheel element. The apparatus comprises: a rotation device arranged to provide a rotation of the wheel element around a rotational axis of the wheel element and a pressing device arranged for pressing the polishing tool against the at least one predetermined surface portion of the wheel element during the rotation of the wheel element.

Thus, the position of the at least one predetermined surface portion can be changed in relation to the polishing tool by rotating the wheel element around the rotational axis of the wheel element. Thereby, the at least one predetermined surface portion of the wheel element can be polished by pressure in an efficient manner thanks to the relative movement of the at least one predetermined surface portion in relation to the polishing tool, which relative movement is achieved, inter alia, by the rotational movement of the wheel element.

Further, the polishing tool is pressed against the at least one predetermined surface portion of the wheel element during the rotation of the wheel element. To achieve a polishing effect of the at least one predetermined surface portion, i.e. a plastic deformation of the at least one predetermined surface portion, the polishing tool needs to have contact with the at least one predetermined surface portion and needs to act with a pressure force on the surface of the at least one predetermined surface portion. The polishing tool is pressed against the at least one predetermined surface portion by a movement of the polishing tool towards the at least one predetermined surface portion to achieve the plastic deformation of the at least one predetermined surface portion. The plastic deformation contributes to a reduction of the tension stresses at the at least one predetermined surface portion.

Consequently, by pressing the polishing tool against the at least one predetermined surface portion during rotation of the wheel element the at least one predetermined surface portion is polished by pressure in an efficient way by using the apparatus.

Thereby the above mentioned object is achieved. The above mentioned object is also achieved by a wheel element for a vehicle, wherein the wheel element comprises at least one predetermined surface portion extending on one side of the wheel element. The at least one

predetermined surface portion has been polished by pressure during a rotation of the wheel element around a rotational axis of the wheel element while a polishing tool has been pressed against the at least one predetermined surface portion of the wheel element during the rotation of the wheel element.

Thus, the position of the at least one predetermined surface portion can be changed in relation to the polishing tool by rotating the wheel element around the rotational axis of the wheel element. Thereby, the at least one predetermined surface portion of the wheel element can be polished by pressure in an efficient manner thanks to the relative movement of the at least one predetermined surface portion in relation to the polishing tool, which relative movement is achieved, inter alia, by the rotational movement of the wheel element.

Further, the polishing tool is pressed against the at least one predetermined surface portion of the wheel element during the rotation of the wheel element. To achieve a polishing effect of the at least one predetermined surface portion, i.e. to achieve a plastic deformation of the at least one predetermined surface portion, the polishing tool needs to have contact with the at least one predetermined surface portion and needs to act with a pressure force on the surface of the at least one predetermined surface portion. The polishing tool is pressed against the at least one predetermined surface portion by a movement of the polishing tool towards the at least one predetermined surface portion to achieve the plastic deformation of the at least one predetermined surface portion. The plastic deformation contributes to a reduction of the tension stresses at the at least one predetermined surface portion.

Consequently, by pressing the polishing tool against the at least one predetermined surface portion during rotation of the wheel element the at least one predetermined surface portion is polished by pressure in an efficient way by using the apparatus.

Thereby the above mentioned object is achieved. BRIEF DESCRIPTION OF THE DRAWINGS In the following preferred embodiments of the invention are described with reference to the attached drawings, on which:

Fig. 1 is a perspective view of a wheel element and a polishing tool arranged at the wheel element and

Fig. 2 is a side view of the wheel element and of the polishing tool in Fig. 1 , where the polishing tool is illustrated in different positions in relation to the wheel element. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In Fig. 1 a wheel element 1 for a vehicle is illustrated. The wheel element 1 may for example be a wheel hub 1. The wheel element 1 comprises at least one predetermined surface portion 3 extending on one side of the wheel element 1. The at least one predetermined surface portion 3 may also be arranged on both sides of the wheel element 1. The wheel hub 1 in Fig. 1 comprises several predetermined surface portions 3 arranged at a distance d from each other. The distance d is a part of a circle with radius r. The predetermined surface portions 3 are arranged at the radius r, which radius r is a common radius for the predetermined surface portions 3. The distance d may also correspond to an angle a between two neighboring predetermined surface portions 3. The angle a has a vertex c. The wheel element 1 is arranged to rotate around a rotational axis 7 of the wheel element 1. The rotational axis 7 goes through the vertex c.

The predetermined surface portions 3 are separated from each other by respective intermediate portions 11. The predetermined surface portions 3 are elevated in relation to the intermediate portions 11. Thus the predetermined surface portions 3 may be arranged at a higher level comparing to the intermediate portions 11 , which facilitates the polishing by pressure of the at least one predetermined surface portion 3. The elevated predetermined surface portions 3 in relation to the intermediate portions 11 make the contact between the polishing tool 5 and the predetermined surface portions 3 easier. The at least one predetermined surface portion 3 is elevated in relation to the intermediate portions 11 by a height h, shown in Fig. 2.

In Fig. 1 also a polishing tool 5 arranged at the wheel element 1 is illustrated. The polishing tool 5 is illustrated in a position for polishing by pressure of the at least one predetermined surface portion 3. The polishing tool 5 comprises a ball 9 arranged at an outer portion of the polishing tool 5. The outer portion of the polishing tool 5 faces the wheel element 1. The ball 9 is arranged to have contact with the at least one predetermined surface portion 3 during rotation of the wheel hub 1 in order to achieve polishing by pressure of the at least one predetermined surface portion 3.

Each of the predetermined surface portions 3 is arranged adjacent to a bolt opening 13 of the wheel element 1. After the finished manufacturing process of the wheel element 1 , there may exist some remaining tension stresses at the predetermined surface portions 3 that are positioned adjacent to the bolt openings 13. The remaining tension stresses can be at least reduced by polishing by pressure of the predetermined surface portions 3.

The wheel hub 1 is arranged to rotate in a direction f around the rotational axis 7 of the wheel hub 1. The direction f can be a clockwise direction of rotation or can be a counterclockwise direction of rotation of the wheel hub 1 around the rotational axis 7.

The process of rotating the wheel element 1 is described in details in

conjunction to Fig. 2. In conjunction to Fig. 2 also the process of pressing the polishing tool 5 against the at least one predetermined surface portion 3 is depicted.

The pressing of the polishing tool 5 against the at least one predetermined surface portion 3 comprises providing a feeding movement of the polishing tool 5 in at least a direction towards the predetermined surface portion 3 and in a direction along the predetermined surface portion 3. Fig. 2 is a side view of the wheel element 1 and of the polishing tool 5. The wheel element 1 can be rotated around the rotational axis 7 by means of a rotation device 17. The rotation device 17 may comprise a motor 19 and a support elements 21 arranged to transmit a rotational movement from the motor 19 to the wheel element 7 in order to achieve a rotational movement of the wheel element 1 around the rotational axis 7 in a direction f. The wheel element 1 can rotate with a rotational speed of, for example 500-600 revolutions per minute.

During the rotation of the wheel element 1 (the wheel hub 1 ) around the rotational axis 7, the polishing tool 5 is pressed against the at least one predetermined surface portion 3. The pressing of the polishing 5 against the at least one predetermined surface portion 3 comprises moving the polishing tool 5 towards the at least one predetermined surface portion 3 in a first direction a1. The first direction a1 implies a movement of the polishing tool 5 in an axial direction of the polishing tool 5 along an axis 23 of the polishing tool 5 against the at least one predetermined surface portion 3. The movement of the polishing tool 5 along the axis 23 against the at least one predetermined surface portion 3 can imply an increase of pressure forces between the polishing tool 5 and the at least one predetermined surface portion 3. The polishing tool 5 comprises a boll 9 arranged at an outer portion of the polishing tool. The boll 9 is arranged to have contact with the at least one predetermined surface portion 3 in order to polish by pressure the at least one predetermined surface portion 3. Thus, the pressing of the polishing tool 5 against the at least one predetermined surface portion 3 implies pressing of the boll 9 against the at least one predetermined surface portion 3. During rotation of the wheel element 1 and after a predetermined number of revolutions of the wheel element 1 around the rotational axis 7, the polishing tool 5 can be moved in the first direction a1 along the axis 23 towards the at least one predetermined surface portion 3 a predetermined distance in order to polish by pressure of the at least one predetermined surface portion 3. The predetermined distance may for example be 1 mm. The polishing tool 5 may also be moved in a second direction a2 along the axis 23 in a direction from the at least one predetermined surface portion 3.

Further, the polishing tool 5 may be arranged to move along a third direction a3 and along a fourth direction a4. The third direction a3 and the fourth direction a4 are substantially perpendicular to the first direction a1 and to the second direction a2 and to the axis 23 of the polishing tool 5. The movement of the polishing tool 5 along the first direction a1 , the second direction a2, the third direction a3 and the fourth direction a4 is achieved and regulated by an apparatus 15 for controlling the polishing tool 5. The apparatus 15 comprises a pressing device 19 arranged for pressing said polishing tool 5 against the at least one predetermined surface portion 3 of the wheel element 1 during the rotation of the wheel element 1 . The at least one predetermined surface portion 3 is elevated in relation to the intermediate portions 11 by a height h. The height h may for example be between 5 and 150 mm.

The present invention is no limited to the embodiments disclosed but may be varied and modified within the scope of the following claims.