Electric heating – Metal heating – By arc
Reexamination Certificate
2000-09-15
2002-03-19
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06359256
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The invention relates to a changing device for a lens holder of a connecting head for machining a workpiece by means of a laser beam.
2. Description of the Relevant Art
DE 295 07 189 U1 has already disclosed a connecting head for machining a workpiece by means of a laser beam. The laser beam is focused with the aid of a focusing optical system present in a connecting head. The laser beam emerges through a cutting nozzle after traversing the focusing optical system. In this case, the focusing optical system is fitted, such that it can be adjusted in the direction of and transverse to its optical axis, on a lens holder. The lens holder is a withdrawable part and can be inserted into a connecting head housing and withdrawn therefrom. In order to facilitate the machining of the workpiece by means of a laser beam, a process gas emerges under pressure together with the laser beam through the cutting nozzle fitted on the connecting head.
Such connecting heads are used, for example, in laser cutting installations. The laser cutting is extremely flexible by comparison with rival separating methods (punching, sawing, etc.). Changing to new cutting contours, materials or workpiece thicknesses can be performed in this case comparatively quickly and in an automated fashion. A plurality of machine parameters are frequently changed for this purpose, for example the contour program, the laser output, the feed rate, the type and pressure of the process gas, the distance between the connecting head and workpiece, and the focusing position. In addition to matching these parameters, it is, in particular, also frequently necessary to change the focal length of the focusing optical system, the nozzle diameter, the nozzle type etc., thus giving rise to the need to change the focusing optical system and the cutting nozzle.
Since the focusing optical system and the cutting nozzle are subject to wear in normal use, ensuring a high process quality requires regular inspection, possibly with subsequent exchange, or regular exchange of the focusing optical system and cutting nozzle. Both the workpiece to be machined and the laser cutting installation could be damaged by worn or damaged focusing optical systems or cutting nozzles.
In order to permit changing of the focusing optical system, it is known from German Patent Application DE 196 55 127 to integrate in the connecting head a changing device for focusing optical systems, in order to be able to arrange in the machining beam path focusing optical systems of different focal lengths at different distances from the cutting nozzle. The individual focusing optical systems are arranged in this case either on turntables or on slides which are situated in different planes perpendicular to the machining beam path.
JP 10-006 062 discloses a changing device for cutting nozzles of a laser machining head in which a plurality of cutting nozzles are accommodated in a magazine. So as to hold the cutting nozzles in the magazine, the latter has appropriate holes behind the edges of which a flange of the respective cutting nozzle engages in each case when the latter is inserted with a slight pressure. The cutting nozzle is held on the connecting head with the aid of appropriate locking means such that after a cutting nozzle has been set down in the magazine another cutting nozzle can be taken from the magazine with the aid of the connecting head.
In a further known changing device for cutting nozzles (U.S. Pat. No. 5,101,089), it is possible to exchange various cutting nozzle tips which can be held by a bayonet catch on the nozzle body of a connecting head or in a holding device of a magazine. For the purpose of changing the cutting nozzle tip, the latter is pushed into a corresponding holding space and firstly fastened in the holding device by rotating the connecting head such that further rotation releases the bayonet connection between the cutting nozzle tip and the connecting head or the nozzle body. The connecting head can then be withdrawn in order to take another cutting nozzle tip from the magazine by firstly rotating the connecting head to make the bayonet connection between the connecting head and cutting nozzle tip, and then releasing the bayonet connection between the cutting nozzle tip and holding device. When locking and unlocking the bayonet connections, it is also possible in this case to rotate the holding device by means of a motor instead of the connecting head.
SUMMARY OF THE INVENTION
The object of the invention is to provide a changing device which renders it possible to match the connecting head of a laser machining installation quickly and reliably to the particular machining task.
Thus, the invention provides that the changing device for a lens holder of a connecting head for machining a workpiece by means of a laser beam has at least two magazine stations, of which each has a holding device for gripping and holding a lens holder, and an actuating device for fastening means which are provided on the connecting head and fix the lens holder, a locking and unlocking device advantageously being provided as an actuating device.
This renders possible quick and automated changing of a focusing optical system arranged in a lens holder, without the need to undertake substantial changes for automation on the connecting head itself. Particularly when use is made of a connecting head which has a focusing optical system preadjusted in the direction of the optical axis and perpendicular thereto, and which is provided for manually changing the focusing optical system, automatic changing is possible with the aid of the changing device according to the invention without the need to undertake essential changes at the connecting head, since the changing device has all the means required for changing.
In order to achieve particularly flexible automation, it is possible when changing the focusing optical system simultaneously to undertake a change to the focal position and/or the focal length. However, in most cases this also requires simultaneous exchange of the cutting nozzle, since in some circumstances a change in the focal length and/or the focal position can drastically change the laser beam radius in the cutting nozzle region, or the beam caustic. If the cutting nozzle and the laser beam caustic are not coordinated with one another, there can be a severe worsening of the machining quality. In the worst case, the cutting nozzle can burn up and the workpiece to be machined can be damaged.
In order to take precautions here, it is possible for the nozzle opening generally to be selected to be so large that the machining beam always passes acceptably through the nozzle opening independently of the focusing optical systems used. However, this increases the gas consumption and, moreover, does not achieve the optimum possible machining result in many cases.
In order to provide a remedy here, it is possible in principle to provide on the changing device according to the invention further magazine stations at which cutting nozzles can be changed automatically. However, in order to carry out automatic changing of the focusing optical system and another function element of the connecting head, particularly the cutting nozzle, particularly quickly, it is provided in the case of an advantageous embodiment of the invention that provided at each magazine station are a further holding device for gripping and holding a further function element and a further actuating device for fastening means which fix the further function element on the connecting head, with the result that the lens holder and the further function element at the same magazine station can be removed from the connecting head or fitted thereon, the further holding device being constructed, in particular, for gripping and holding a cutting nozzle.
The invention thus renders it possible to change two function elements of a connecting head for a laser machining installation at a single magazine station of a changing device. The connecting head therefore need only be moved to a first
Biermann Stephan
Schubert Peter
LandOfFree
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