Electric heating – Metal heating – By arc
Patent
1993-12-10
1995-08-15
Reynolds, Bruce A.
Electric heating
Metal heating
By arc
21912183, 361115, 2503541, B23K 2600
Patent
active
054421543
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a safety device specifically adapted to automatic machines of the kind that use a laser beam having an infrared wavelength and being of low to very high power, such as a tool for cutting, for welding, for drilling, for heat treatment, for removing material, etc.
1. Background of the Invention
The present invention also relates to a method of implementing the above device to detect deviations of a laser beam.
2. Objects and Summary of the Invention
In general, multi-axis automatic machines that already exist on the market comprise a laser beam generator or laser "source" and an optical path constituted by mirrors that reflect the laser beam so as to bring it to the working portion of the tool such as a head for cutting or for welding. The head may be stationary or it may be moving, either at the end of a robot arm, or using the same principles as an XY plotter, or else it may be on a moving gantry having more than two axes.
One of the main problems with machines of that type lies in the need to ensure safety for personnel and for the machine. Given the technology used (beam being conveyed by mirrors) it may happen that the laser beam is deflected from its initial path and then becomes a danger to the safety of human beings and of equipment.
One of the techniques used in the context of providing safety for laser machines consists in protecting access to the optical path of the laser by caps, bellows, and passive diaphragms (metal tubes through which the laser beam passes). This technique has the drawback of not making it possible to detect deflection of the beam path, should that occur, since the passive diaphragms serve merely to absorb all or a fraction of the beam energy as a function of the power of the laser. That method therefore continues to leave some risk for equipment and for personnel.
Other techniques exist that seek to obtain continuous control of the alignment of the laser beam. To do that, temperature sensors (thermocouples, hot wires, . . . ) are disposed around the periphery of a section through which the beam passes. Any unbalance in the heating of one of the sensors compared to the others provides information (direction, magnitude, . . . ) about the deviation of the laser beam from its normal trajectory. The information is processed electronically by a computer for the purpose of automatically correcting the deviation of the mirrors so as to realign the beam on its ideal trajectory. That method is very expensive and it is used only on systems that require continuous monitoring of laser beam alignment, and it suffers from the additional drawback of using a computer to manage safety. In order to be genuinely effective and reliable, safety means must act directly on the laser beam control circuit without any need for computer processing. In addition, if the power of the laser is too high, then the temperature sensors may be damaged and become useless.
An object of the invention is to solve the above technical problems in satisfactory manner.
According to the invention, this object is achieved by means of a safety device for using a laser beam from a source following a determined optical path that optionally includes mirrors each associated with an operating network for a beam monitoring signal, the device being characterized in that said operating network comprises at least one removable signal interrupter element disposed on the optical path and constituted at least in part by a conductor for said signal that surrounds said beam and that is suitable for interacting with the beam in the event of the beam deviating, thereby instantaneously causing the monitoring signal to be interrupted and thus causing the beam to be interrupted.
In a first embodiment, said interrupter element is entirely conductive.
In another embodiment, said signal conductor is characterized by a frame whose central axis coincides with the normal direction of the beam and which is secured to a support member provided with means for connecting said conductor to the op
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Philippe Michel
Soulignac Benoit
Lectra Systems
Mills Gregory L.
Reynolds Bruce A.
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