HONING MACHINE FOR BEARING RINGS AND METHOD FOR FEEDING SUCH A MACHINE WITH BEARING RINGS
A honing machine for bearing rings includes a frame, a honing tool, a honing station for holding a bearing ring in position with respect to the honing tool, the honing station includes a work piece holder with a concave surface equipped with at least one pad for supporting a bearing ring. The work piece holder is equipped with a damper movable between a first active configuration and a second passive configuration. In the first active configuration, the damper protrudes on a path of a bearing ring moving towards the work piece holder in the honing station. In the second passive configuration, the damper is out of reach of a bearing ring in the honing station.
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This is a Non-Provisional Patent Application, filed under the Paris Convention, claiming the benefit of Europe (EP) Patent Application Number 15305316.0, filed on 2 Mar. 2015 (02.03.2015), which is incorporated herein by reference in its entirety.
TECHNICAL FIELD OF THE INVENTIONThis invention relates to a honing machine which can be used for a honing process on bearing rings. This invention also relates to a method for feeding a honing machine with bearing rings.
BACKGROUND OF THE INVENTIONIn the field of bearings manufacturing, it is known to use a honing machine provided with a honing tool or “honing stone” which is brought into contact with a raceway of a bearing ring, in order to improve its finish. During a honing process, each bearing ring is held in a honing station and driven in rotation with respect to the honing tool which remains stationary. A bearing ring present in the honing station must be supported by a work piece holder which is generally provided with pads mounted on a concave surface which is shaped according to the dimensions of the bearing rings to be processed in the honing machine. The pads are used to precisely center each bearing ring with respect to a rotation axis of a rotatable member which drives the bearing ring in rotation with respect to the honing stone. Thus, it is essential that the pads are correctly positioned with respect to the rotation axis.
When the honing station is fed by gravity with bearing rings, pads made of a hard material are difficult to use, since there exists a risk of breakage of the pads, upon the impact of a ring entering the honing station. An alternative consists in using relatively soft pads, such as pads made of a synthetic material. A drawback of this approach is that such pads tend to wear off, so that they do not allow a precise positioning of the bearing rings with respect to the rotation axis.
Moreover, a bearing manufacturer generally offers a range of bearings whose inner and outer rings have different dimensions. Thus, bearing rings with different dimensions have to be successively processed on a honing machine. When it is needed to switch the honing machine from a configuration where it handles a first type of bearing rings to another configuration where it handles a second type of rings, the work piece holder has to be changed and carefully positioned with respect to a frame of the honing machine. Because of the limitations of the current work piece holders, such an operation implies that a dummy bearing ring must be located in the honing station and manually centered on the rotation axis in order to be used as a reference for the pads of a new work piece holder to be installed in the honing station. This complicated setting operation is time consuming and requires a highly qualified manpower.
SUMMARY OF THE INVENTIONThe present invention aims at solving these problems with a new honing machine having a work piece holder which can be provided with hard and long-lasting pads, with a low breakage risk.
To this end, the invention concerns a honing machine for bearing rings, this machine including a frame, a honing tool, a honing station for holding a bearing ring in position with respect to the honing tool, the honing station including a work piece holder with a concave surface equipped with at least one pad for supporting a bearing ring. According to the invention, the work piece holder is equipped with a damper movable between a first active configuration, where it protrudes on a path of a bearing ring moving towards the work piece holder in the honing station, and a second passive configuration, where it is out of reach of a bearing ring in the honing station.
Thanks to the invention, the damper is capable of preventing a direct impact between a bearing ring entering the honing station and the pads of the work piece holder. Since the pads are not subjected to a large number of impacts, they can be made in a hard material, which allows them not to wear off as quickly as pads made of a synthetic material. Since the pads do not wear off, their dimensions remain constant and the work piece holder can be installed within the honing station without having to use a dummy bearing ring.
According to further aspects of the invention which are advantageous but not compulsory, such a honing machine can incorporate one or several of the following features:
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- Each pad of the work piece holder is coated with a high stiffness material, in particular with a layer of polycrystalline diamond.
- The damper includes a pin, which is movable in translation along a vertical axis, and damping means for braking a vertical downward displacement of the pin.
- The pin is movable along the vertical axis between a first position, where it protrudes upwardly with respect to an adjacent pad of the work piece holder, and a second position, where an upper surface of the pin is below an upper surface of the adjacent pad.
- The damping means include a rotatable shaft movable in rotation around its longitudinal axis, between a first angular position where it interacts with a vertical downward movement of the pin between its first and second positions and a second angular position where the shaft is out of reach of the pin, and a gas cylinder for moving the shaft between its first and second positions, and reverse.
- The shaft is provided with a paddle which lies on the downward path of the pin between its first and second positions, when the shaft is in its first angular position, and which is away from the downward path, when the rotating shaft is in its second angular position.
- The paddle is secured to a first end of the shaft and the gas cylinder is connected by a rocker arm to a second end, opposite to the first end, of the shaft.
- The honing machine includes elastic means for biasing the pin downwardly.
- The elastic means bias the pin against the paddle when the rotating shaft is in its first angular position.
- The elastic means is a coil spring mounted around the pin and compressed between a lower surface of the work piece holder and a peripheral shoulder of the pin.
- The work piece is provided with a vertical through hole and the pin is slidably movable inside the vertical through hole.
- The pin has an upper head for receiving an outer surface of a bearing ring, the concave surface of the work piece holder has a stepped portion, which is below an exposed surface of an adjacent pad and the upper head of the pin is accommodated above the stepped portion of the upper surface of the work piece holder and at a level below the upper surface of the adjacent pad when the damper is in its second passive configuration.
- The honing machine includes a transfer mechanism for feeding the honing station with bearing rings, one after the other, the transfer mechanism including a first transfer box, adapted to accommodate a bearing ring and movable in translation, in a to-and-fro movement with respect to the frame, along a first axis, a second transfer box, adapted to accommodate a bearing ring and movable in translation, in a to-and-fro movement with respect to the frame, along a second axis parallel to the first axis, first driving means for driving the first transfer box in translation along the first axis and second driving means for driving the second transfer box in translation along the second axis, in such a way that the second transfer box is located under and adjacent the first transfer box, above the honing station, and that the second transfer box has a top inlet opening which is vertically aligned with a bottom outlet opening of the first transfer box.
The invention also concerns a method for feeding a honing station of a honing machine as described here-above. Such a method includes at least the following steps consisting in:
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- a) setting the damper in its first active configuration
- b) introducing the bearing ring by gravity into the honing station up to a point where it contacts the damper
- c) setting the damper in its second passive configuration
Moreover, when the damper of the honing machine includes a pin movable in translation along a vertical direction as mentioned here-above, it can be provided that, during step c), an upper surface of the pin is moved downwardly by gravity up to a level where it is below an upper surface of an adjacent pad of the work piece holder.
The invention will be better understood on the basis of the following description which is given in correspondence with the annexed figures and as an illustrative example, without restricting the object of the invention. In the annexed figures:
The honing machine 2 represented on
Honing machine 2 also includes a movable frame 12 slidable, with respect to base frame 4, along a fixed longitudinal axis X4, in two opposite directions, as shown by double arrow A1. A non-represented actuator, such as an electric motor or a pneumatic or hydraulic cylinder, drives movable frame 12 in translation along axis X4.
Movable frame 12 supports a honing station 14 where a bearing ring 100 is held in position for interaction with the honing stone 8. More precisely, movable frame 12 supports a rotary actuator, in the form of an electric motor 16, which is adapted to drive bearing ring 100 present in holding station 14 around a rotation axis X14 which is fixed with respect to frame 12 and parallel to axis X4. Movable frame 12 supports a holding mechanism 17 provided with two rollers 172 adapted to come into contact with a lateral surface of bearing ring and to push this ring towards electric motor 16, in order to make a friction type connection between bearing ring 100 and a rotating member 162 driven by motor 16 in rotation around axis X14. Actually, holding mechanism 17 is movable with respect to frame 12, in translation along an axis X17 parallel to axes X4 and X14, between a loading configuration of honing machine 2 represented on
In the following description, unless otherwise specified, one considers honing machine 2 in its loading configuration. For the sake of clarity, items 4 to 10 and 17 are omitted on
Honing station 14 includes, amongst others, a work piece holder 18 which has a concave surface 182, with a section perpendicular to axis X14 in the form of an arc of a circle centered on axis X14. This work piece holder is selected in order to match the outer dimensions of bearing rings to be processed by honing machine 2. Thus, work piece holder is generally changed when a new type of bearing rings is to be processed in honing machine 2.
Honing machine 2 also includes a transfer mechanism 20 which is used to successively feed honing station 14 with bearing rings stored in an inlet chute 22.
Transfer mechanism 20 includes a first transfer box 202 and a second transfer box 204 which is located immediately below the first transfer box.
In the present description, the words “below”, “above”, “inferior” or “superior” relate to a working configuration of honing machine 2. “Above” or “superior” relates a surface or a part which is oriented towards the top of machine 2 in such a configuration, whereas “below” or “inferior” relates to a surface or a part which is oriented to the bottom of this machine.
First transfer box 202 is visible alone on
Spacer 2024 extends on the whole height of side walls 2020 and 2022 and protrudes downwardly with respect to these two walls. Spacer 2026 extends between lower parts of side walls 2020 and 2022, so that an inlet opening 202A is defined on the lateral side of box 202 visible on
Reference character 2026A denotes the upper surface of spacer 2026. This upper surface 2026A is inclined towards outlet opening 202B. In other words, this surface lowers in the direction of outlet opening 202B.
Reference characters 2024B and 2026B respectively denote the vertical surfaces of spacers 2024 and 2026 which face each other. In the direction of axis Y202, outlet opening 202B is defined between surfaces 2024B and 2026B. Reference character D2 denotes the distance measured between surfaces 2024B and 2026B along axis Y202.
Second transfer box 204 also includes two metallic side walls 2040 and 2042 and two synthetic spacers 2044 and 2046. An inspection window 2048 is provided in side wall 2042 and allows inspection of the inside volume V204 of second transfer box 204. An inlet opening 204A of second transfer box 204 is defined between the top edges of side walls 2040 and 2042. An outlet opening 204B of second transfer box 204 is defined between spacers 2044 and 2046, below the respective central portions of the lower edges of side walls 2040 and 2042.
Reference character 2046A denotes the upper surface of spacer 2046. This surface is horizontal.
Reference character 2046B denotes an end face of spacer 2046 oriented towards spacer 2044. Outlet opening 204B is defined, along axis Y204, between spacer 2044 and end face 2046B.
In working configurations of transfer mechanism 20, inlet opening 204A is vertically aligned with outlet opening 202B, so that a bearing ring can go from volume V202 into inside volume V204 by gravity.
Transfer mechanism 20 also includes a first pneumatic cylinder 206 mounted on frame 12 and adapted to drive first transfer box 202 in translation along an axis Y202 which is horizontal and perpendicular to axis X4. Double arrow A2 represents the to-and-fro movements of first transfer box 202 in the direction of axis Y202. Cylinder 206 is a rodless cylinder whose output member is connected to first transfer box 202.
A second pneumatic cylinder 208 is mounted on movable frame 12 and its output member is connected to second transfer box 204 and drives this box in translation along a second axis Y204 which is parallel to axis Y202. Double arrow A4 shows the to-and-fro movements of second transfer box 204 along axis Y204.
Honing machine 2 also includes an inlet chute 22 and an outlet chute 24. In machine 2, bearing rings go from inlet chute 22 to outlet chute 24 via transfer mechanism 20 and honing station 14.
Outlet chute 24 is provided with a side wall 242 and an inductive sensor 244 which allows detecting the presence of a bearing ring in an inside volume V24 of chute 24, when the ring lies or rolls on a lower surface 246 of outlet chute 24.
For the sake of clarity, side walls 2022, 2042 and 242 are omitted on
An inlet gate 26 is arranged between inlet chute 22 and transfer mechanism 20 and this inlet gate is controlled by a pneumatic cylinder 28.
In this example, cylinders 206, 208 and 28 respectively form actuators for items 202, 204 and 26. Alternatively, other types of actuators can be used, for instance hydraulic cylinders, mechanical jacks or electric motors.
As shown on
The exposed surface 184A or 186A of each pad 184 or 186 is advantageously formed of a layer of polycrystalline diamond or “PCD”, which presents a high mechanical stiffness. This high stiffness layer has a thickness between 1 and 500 μm and is applied on an armature 184B or 86B made for instance of carbide, with a thickness between 0.1 and 10 mm, preferably equal to about 0.2 mm. Alternatively, armature 184B or 186B and the high stiffness layer can be made in other materials with suitable mechanical properties to resist wear, shocks and lower the variation of dimensions with temperature and time. On
A through hole 188 is provided on work piece holder 18 and extends vertically and downwardly from a stepped portion 182A of concave surface 182. Through hole 188 is visible on
Z188 denotes the central axis of through hole 188. A metallic pin 190 is slidably mounted within through hole 188 and movable along axis Z188 between a first position, represented on
As shown on
A shaft 30 is mounted on movable frame 12 next to work piece holder 18 and its longitudinal axis Y30 is parallel to axes Y202 and Y204. Actually, shaft 30 is rotatably supported by movable frame 12, so that it can rotate around axis Y30 between a first position, represented on
A first end 302 of shaft 30 is equipped with a paddle 304 which extends radially with respect to axis Y30, so that it is located directly below sole 194 in the configuration of
The second end 308 of shaft 30, which is opposite to first end 302, is connected to a rocker arm 310. The end of rocker arm 310 opposite to shaft 30 is connected to an output rod 320 of a gas cylinder 32. Thus, gas cylinder 32 forms an actuator which allows pivoting shaft 30, in rotation around axis Y30, between the position of
A non-represented pneumatic control unit is connected to cylinders 206, 208, 28 and 32 and pilots these actuators, according to a predetermined sequence, which is explained here-below.
Feeding of honing station 14 is now explained in connection to
On these figures, a bearing ring present in honing station 14 is referenced 100, whereas a bearing ring to be fed to honing station 14 is referenced 102.
Thus, inside volume V202 of first transfer box 202 accommodates bearing ring 102 until it falls down into inside volume V204 of second transfer box 204. In the configuration of
In the configuration of
From the configuration of
Due to the movement of second transfer box 204 between the configuration of
Cylinder 206 is piloted in a next step in order to move first transfer box 202 along axis Y202 in the same direction as second transfer box 204 has been moved previously, as shown by arrow A10 on
The platform formed by spacer 2046 temporary holds bearing ring 102 within inside volume V204, from the configuration of
As shown on
Once this detection has occurred, it is sure that no bearing ring remains in honing station 14, so that this honing station can be loaded again with bearing ring 102. To this end, second transfer box 204 is moved along axis Y204 in the opposite direction, as shown by arrow A12 on
From this configuration and because of gravity, ring 102 falls into honing station 14, as shown by arrow A13 on
The downward movement of ring 10 is dampened by pin 190, which protrudes upwardly from pad 184 on the downward path of bearing ring 102, since work piece holder 18 is in the configuration of
Once this dampening or braking effect of the downward movement of ring 102 has been obtained with the damper formed of pin 190, shaft 30 and cylinder 32, cylinder 32 is actuated to push rod 320 outwardly, so that rocker arm 310 and shaft 30 are brought into the configuration of
Then ring 102 reaches the configuration of
In other words, thanks to the use of pin 190, shaft 30 and gas cylinder 32, it is possible to use high resistance pads 184 and 186, without risk of breaking pads 184 or 186 or caulking the outer radial surface of ring 102.
In the configuration of
At a later stage, which corresponds to the configuration of
Throughout the process described here-above, inspection windows 2028 and 2048 allow checking the position of bearing ring 102 in transfer mechanism 20.
Claims
1. A honing machine for bearing rings, this machine including:
- a frame;
- a honing tool;
- a honing station for holding a bearing ring in position with respect to the honing tool, the honing station including a work piece holder with a concave surface equipped with at least one pad for supporting a bearing ring; and
- a damper, the damper being movable between a first active configuration and a second passive configuration,
- where, in the first active configuration, the damper protrudes on a path of a bearing ring moving towards the work piece holder in the honing station,
- where, in the second active configuration, the damper is out of reach of a bearing ring in the honing station.
2. The honing machine according to claim 1, wherein each pad of the work piece holder is coated with a high stiffness material, in particular with a layer of polycrystalline diamond.
3. The honing machine according to claim 1, wherein each pad of the work piece holder is coated with a layer of polycrystalline diamond.
4. The honing machine according to claim 1, the damper further including a pin and a damping feature,
- wherein the pin is movable in translation along a vertical axis,
- wherein the damping component is adapted for braking a vertical downward displacement of the pin.
5. The honing machine according to claim 4, the work piece further comprising a vertical through hole,
- wherein the pin is slidably movable inside the vertical through hole.
6. The honing machine according to claim 4,
- the pin further comprising an upper head, wherein the upper head is adapted to receive an outer surface of a bearing ring; and
- the concave surface of the work piece holder further comprising a stepped portion, wherein the stepped portion is located below an exposed surface of an adjacent pad;
- wherein the upper head of the pin is accommodated above the stepped portion of the upper surface of the work piece holder and at a level below the upper surface of the adjacent pad, when the damper is in its second passive configuration.
7. The honing machine according to claim 4, wherein the pin is movable along the vertical axis between a first position and a second position,
- wherein, in the first position, the pin protrudes upwardly with respect to an adjacent pad of the work piece holder,
- wherein, in the second position, an upper surface of the pin is positioned below an upper surface of the adjacent pad.
8. The honing machine according to claim 7, the damping feature further including:
- a rotatable shaft movable in rotation around its longitudinal axis, between a first angular position where it interacts with a vertical downward movement of the pin, between its first and second positions, and a second angular position where the shaft is out of reach of the pin; and
- a gas cylinder for moving the shaft between a first position of the shaft and a second position of the shaft, and reverse.
9. The honing machine according to claim 8, the shaft further comprising a paddle,
- wherein the paddle lies on the downward path of the pin between a first position of the paddle and a second position of the paddle, when the shaft is in a first shaft angular position, and which is away from the downward path, when the rotating shaft is in its second angular position.
10. The honing machine according to claim 9, wherein the paddle is secured to a first end of the shaft and the gas cylinder is connected by a rocker arm to a second end, opposite to the first end, of the shaft.
11. The honing machine according to claim 8, further comprising an elastic element for biasing the pin downwardly.
12. The honing machine according to claim 11, wherein the elastic element biases the pin against the paddle when the rotating shaft is in its first angular position.
13. The honing machine according to claim 11, wherein the elastic element is a coil spring,
- wherein the coil spring is mounted around the pin and compressed between a lower surface of the work piece holder and a peripheral shoulder of the pin.
14. The honing machine according to claim 1, further comprising a transfer mechanism for feeding the honing station with bearing rings, one after the other, the transfer mechanism including:
- a first transfer box, adapted to accommodate a bearing ring and movable in translation, in a to-and-fro movement with respect to the frame, along a first axis,
- the first transfer box including a bottom outlet opening,
- a second transfer box, adapted to accommodate a bearing ring and movable in translation, in a to-and-fro movement with respect to the frame, along a second axis, the second axis being parallel to the first axis,
- the second transfer box including a top inlet opening,
- a first driving mechanism for driving the first transfer box in translation along the first axis and
- a second driving mechanism for driving the second transfer box in translation along the axis direction,
- wherein the second transfer box is located under and adjacent the first transfer box, above the honing station, and that the second transfer box has a top inlet opening which is vertically aligned with a bottom outlet opening of the first transfer box.
15. A method for feeding a honing station of a honing machine with a bearing ring, the honing machine comprising:
- a frame;
- a honing tool;
- a honing station for holding a bearing ring in position with respect to the honing tool, the honing station including a work piece holder with a concave surface equipped with at least one pad for supporting a bearing ring; and
- a damper, the damper being movable between a first active configuration and a second passive configuration,
- wherein, in the first active configuration, the damper protrudes on a path of a bearing ring moving towards the work piece holder in the honing station,
- wherein, in the second active configuration, the damper is out of reach of a bearing ring in the honing station, the method comprising steps of:
- a) setting the damper in a damper first active configuration;
- b) introducing the bearing ring by gravity into the honing station up to a point where the bearing ring contacts the damper; and
- c) setting the damper in its second passive configuration.
16. The method according to claim 15, the damper further including a pin and a damping feature,
- wherein the pin is movable in translation along a vertical axis,
- wherein the damping component is adapted for braking a vertical downward displacement of the pin,
- during the step of setting the damper in its second passive configuration, the method further comprising a step of moving an upper portion of the pin downwardly by gravity up to a level where it is below an exposed surface of an adjacent pad of the work piece holder.
Type: Application
Filed: Feb 5, 2016
Publication Date: Sep 8, 2016
Applicant: Aktiebolaget SKF (Goteborg)
Inventors: Renaud BELLANGER (Notre Dame D'Oe), Eric CORSET (Rouziers de Touraine), Alexandre KAELIN (Blois), Denis LANSIGU (VILLEDOMER), Gilles PROUST (Neuille-Pont-Pierre)
Application Number: 15/016,482