This is a Non-Provisional Patent Application, filed under the Paris Convention, claims the benefit of European Patent (EP) Application Number 14305614.1 filed on 25 Apr. 2014 (25.04.2014), which is incorporated herein by reference in its entirety.
This invention relates to a workpieces processing machine which can be used, for instance, for the grinding of bearing rings and which includes, amongst others, a handling tool for loading a workstation of the machine with workpieces to be processed. This invention also relates to a method for automatically controlling the dimensions of workpieces to be processed in a working station of such a machine.
In the field of manufacturing, it is known that the dimensions of the workpieces to be processed on a machine must be checked in order to avoid processing of a workpiece with wrong parameters of the machine. On some machines, this is implemented via Poka Yoke devices which include a mechanical part installed on a feeding line of a machine and adapted to block workpieces having one dimension larger than the nominal dimension of the workpieces to be processed. Such a Poka Yoke device must be installed for each type of workpiece to be processed on a machine which is time consuming and requires storing Poka Yoke devices not currently used on a machine. Moreover, such a Poka Yoke device generally allows controlling only one dimension of a workpiece, which might not be sufficient to differentiate two types of workpieces.
This is particularly the case in a grinding machine for bearing rings, such as the one known from WO-A-2008/082140, where several bearing rings with the same diameter might be processed, while having different axial length.
This problem also occurs in other processing machines capable of handling different types of workpieces.
This invention aims at solving these problems with a new machine which is capable of handling different workpieces, without having to use Poka Yoke devices which need to be changed for every new type of workpiece to be processed.
To this end, the invention concerns a workpieces processing machine comprising a handling tool for loading a working station of a machine with workpieces to be processed, this machine being characterized in that it includes a laser detection cell and computation means configured to compute at least a first dimension of a workpiece on the basis of a position of the handling tool when the workpiece crosses a laser beam of the laser detection cell while being moved by the handling tool in a first direction.
Thanks to the invention, the laser beam of the laser detection cell is used as a reference and the computation means are capable of determining a dimension of a workpiece without having to be changed from one type of workpiece to another.
According to further aspects of the invention, which are advantageous but not compulsory, this machine might incorporate one or several of the following features, taken in any admissible configuration:
The invention also relates to a method which can be implemented with a machine as mentioned here-above for automatically controlling the dimensions of some workpieces to be processed in a working station of this machine. This method includes at least the following steps consisting in:
According to further aspects of this method, it might incorporate one or several of the following features taken in any admissible configuration:
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 grinding machine 2 represented on
Grinding wheel 6 and motor 8 are supported by an auxiliary frame 9 which is movable with respect to frame 4 in two opposite directions perpendicular to axis X6, as shown by double arrow A9 on
The outer peripheral surface 10 of grinding wheel 6 is shaped by a knurl 12 when needed and is used to grind the outer surface of an inner ring 500 of a non-further represented bearing. Knurl 12, which is sometimes called “diamant roller”, is also supported by auxiliary frame 9. In the example of the figures, outer surface 10 has a central bump, so that it is used to grind the outer radial surface 502 of ring 500 with a concave groove.
Grinding machine 2 is provided with a working station or zone 14 where each ring 500 is successively held in position with respect to grinding wheel 6 during a grinding operation.
Working station 14 includes two support shoes 16 and 18, each provided with a fitting 20, respectively 22. Fitting 20 is adapted to lie against the outer radial surface of a magnetic clamp 24, whereas fitting 22 is made of two parts and adapted to lie against the outer peripheral surface 502 of ring 500. Each support shoe 16 and 18 is mounted on a slider 26, respectively 28. Another slider 30 is used to avoid escape of the ring 500.
When it is loaded in working station 14, as shown on
Two types of equipment are used to feed working station 14 with rings 500 and to evacuate the rings from this working station, once they have been processed. In this description, a ring which is not yet processed is called a “black ring”, whereas a ring which has been processed by grinding wheel 6 is called a “ground ring”.
A multi-axis robot 100, with 6 degrees of freedom, belongs to the transfer means. It is mounted by its base 102 on the frame 4 of grinding machine 2 and includes a multi-articulated arm 104 whose free end is equipped with a clamp 106 adapted to grasp or grip different types of rings 500, via a proper programming of robot 100.
A moving arm 200 also belongs to the transfer means. This moving arm is rotatable around an axis X200 which is fixed with respect to frame 4 and parallel to axis X6. Near its free end 204 opposite to axis X200, moving arm 200 is provided with means for gripping a ring 500 to be moved away from working station 14. This gripper 206 allows temporally gripping a ring 500.
Grinding machine 2 includes an inlet chute 300 where black rings 500 move by gravity in the direction of arrow A300. For the sake of simplicity, only one ring 500 is represented in inlet chute 300 on
On the other hand, grinding machine 2 also includes an outlet chute 310 where ground rings 500 are dumped, one after the other. In outlet chute 310, ground rings 500 move by gravity, in the direction of arrow A310. On its side oriented towards arm 200, outlet chute 310 is equipped with a releaser 312 provided with a notch 314 of a size sufficient to accommodate the gripping means of moving arm 200 but with a transverse dimension, measured between two lateral edges of this notch, smaller than the outer diameter of the rings 500.
Grinding machine 2 includes an electronic control unit or ECU 600 which is schematically represented on
A laser detection cell 650 is mounted on inlet chute 300 and includes a U-shaped frame 652 and two posts 654A, 654B for holding frame 652 with respect to two lateral walls of inlet chute 300. A laser beam B650 extends between the two lateral legs of frame 652. Laser detection cell 650 is connected to ECU 600 and capable of sending to ECU 600 output signal S650 when laser beam B650 is interrupted by an obstacle, so that ECU 600 knows when laser beam 650 is being interrupted.
When a black bearing ring 500 is picked up within inlet chute 300, as shown in
Actually, as shown on
D500A denotes the outer diameter of ring 500 at the level of the bottom of groove 502A. D500B and D500C respectively denote the outer diameters of ring 500 at the level of surfaces 502B and 502C. L500 denotes the axial length of ring 500 measured between surfaces 506 and 5063B, along axis X500.
When multi-axis robot 100 picks up a black bearing ring 500 to be processed in working station 14 of machine 2, it is essential to be sure that dimensions D500A, D500B, D500C and L500 correspond to the ones for which the working parameters of grinding machine 2 have been set up. Thus, multi-axis robot 100 and laser detection cell 650 are used to verity that these parameters are correct. To this end, bearing ring 500 is moved along a direction D1 up to when it reaches the configuration of
When this occurs, a corresponding signal S650 is sent by cell 650 to ECU 600 which knows the instantaneous position and configuration of clamp 106 thanks to the feedback signals sent by the sensors of multi-axis robot 100 and clamp 106.
Thereafter, multi-axis robot 100 moves ring 500 away from laser beam B650 and, afterwards, multi-axis robot 100 moves bearing ring 500 once again towards laser beam B650, this time along a second direction D2, as shown on
Thus, ECU 600 is capable of comparing the two positions of clamp 106 in the configuration of
On the other hand, multi-axis robot 100 can be used to move clamp 106 to the position of
The same approach is used in the configurations of
On
Thanks to the invention, several dimensions D500A, D500B, D500C and L500 of a bearing ring 500 can be checked before this ring is fed to the working station 14 of grinding machine 2. The successive checks, implemented in the steps corresponding to the configuration of
The order of the steps respectively represented by the configuration of
Once dimensions D500A, D500B, D500C and L500 have been determined by ECU 600, as explained here-above, they can be compared to reference values representative of the bearing rings to be processed in machine 2 with its current settings. Depending on the result of the comparison, a bearing ring 500 which has been checked is moved to working station 14 or not.
No change has to be done to items 600 and 650 to handle different types of workpieces insofar as the handling of bearing rings of different dimensions is fully implemented through the computations made in electronic control unit 600.
The invention is explained here-above and represented on the figures in case it is used for a grinding machine for bearing rings, which is a particularly interesting embodiment of the invention. However, the invention can also be implemented with other types of workpieces processing machine where different types of workpieces have to be processed.
Number | Date | Country | Kind |
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14305614.1 | Apr 2014 | EP | regional |