Laser processing head with hold-down device

Abstract

The invention relates to a processing head for guiding a laser beam of a laser processing machine with a hold-down device (10) for a workpiece to be processed, which holds the laser beam in a ring shape and has a contact device (12) which slides over the workpiece surface and is fixed to the laser processing head by means of a fastening device (11), wherein the fastening device (11) and the contact device (12) are connected to one another by means of a connecting device (14) which is elastically compressible at least in the vertical direction.

Description

The invention relates to a machining head for guiding a laser beam of a laser machining machine, having a holding-down device for a workpiece to be machined, which holding-down device surrounds the laser beam at least in sections and has a contact device which slides over the workpiece surface and is fixed to the laser machining head by means of a fastening device.In the laser machining of workpieces, it is known to provide a holding-down device on the laser machining head, which holding-down device presses the workpiece against a workpiece support during machining in order to allow reliable and precise machining of the workpiece. The contact device of the holding-down device slides over the workpiece surface together with the laser machining head. During the processing of wavy workpieces, for example of sheets or uneven semi-finished product wavy due to temperature influences or due to punching processes, it may, however, occur that the holding-down device is pressed upward by the workpiece. In order to avoid damage to the machining head, the holding-down devices are therefore frequently arranged on the machining head so as to be movable in the vertical direction. The holding-down device can also comprise a beam protection function, wherein a reliable interrogation of the state or an accurate detection of the position is required. However, if the displacements of the holding-down device on the machining head are too great, this can trigger a switching off of the laser beam, which leads to undesired interruptions in the machining of the workpiece.The object of the invention is to provide a machining head for laser machining machines with a holding-down device which also allows machining of wavy workpieces without a disconnection of the laser beam or damage to the machining head.This object is achieved according to the invention by a processing head for guiding a laser beam of a laser processing machine, having a holding-down device, which annularly surrounds the laser beam, for a workpiece to be processed and has a contact device which slides over the workpiece surface and is fixed to the laser processing head by means of a fastening device, wherein the processing head is characterized in that the fastening device and the contact device are connected to one another by means of a connecting device which is elastically compressible at least in the vertical direction.The dependent claims relate to preferred embodiments.The holding-down device arranged at least in sections can be U-shaped or preferably annular.The elastically compressible connecting device between the contact device and the fastening device of the hold-down device ensures that lifting the contact device by a wavy workpiece does not lead to the laser beam being switched off by a displacement of the fastening device on the machining head or even to damage to the machining head. The connecting device catches the lifting movement of the contact device, so that the contact device is not forwarded to the fastening device. This also enables highly wavy workpieces to be machined without undesired disconnection of the laser beam or damage to the machining head.The connecting device can preferably have a plurality of elastic force elements. The number and configuration of the individual force elements can influence the elasticity of the connecting device in the desired manner.Suitable force elements are, in particular, leaf springs, helical springs, hydraulic or pneumatic cylinders or rubber elements. These can advantageously be distributed uniformly over the circumference of the holding-down device in order to ensure a uniform effect of the connecting device in all movement directions of the processing head.Further advantages result if the connecting device is designed such that it allows passive gimbal movement of the contact device by action of the workpiece to be machined. The contact device can thus also be brought into an inclined position by the workpiece and at least to a limited extent also execute lateral movements. As a result, the holding-down function of the holding-down device can be significantly improved.The contact device can be provided with flexible bristles on its underside in a manner known per se. The bristles allow damage-free sliding of the hold-down device over the workpiece surface and compensate for smaller elevations on the workpiece surface due to their flexibility. In addition, the bristles shield the laser beam from the outside and thus reduce the risk of injury to the operating personnel of the laser processing machine.In order to ensure the most symmetrical possible action of the holding-down device, the contact device and the fastening device can preferably be configured annularly, for example as steel rings. The connecting device arranged between the contact device and the fastening device thereby has the same radial distance from the laser beam over the entire circumference of the holding-down device.In the machining head according to the invention, the fastening device can also be arranged vertically displaceably on the machining head. In this case, the vertical position of the fastening device can be monitored by a sensor device connected to a controller of the laser machining head. In this way, it is possible to shut off the laser beam in the event of very large unevennesses of the workpiece. In addition, the entire machining head can be raised to avoid damage.Further advantages can be achieved if the holding-down device is surrounded by a cylindrical laser shielding device. For the purposes of this invention, "cylindrical laser shielding device" is generally understood to mean laser shielding device having a circular, oval, or polygonal base surface or cross-sectional surface. This ensures that even in the case of three-dimensional machining of the workpiece, which also require oblique positions of the machining head, the laser beam can be shielded from the outside in order to avoid a risk of injury to the operating personnel of the laser machining machine.For this purpose, the laser shielding device can preferably have a plurality of tab-shaped shielding elements arranged adjacent to one another in the circumferential direction of the holding-down device. These flaps are opaque, in particular opaque to radiation, and can also be arranged overlapping one another. Its flexibility does not impair the action of the hold-down device with the elastic connecting device. Such a shielding device can largely replace the provision of expensive protective housings for the laser processing machine.The invention also relates to a holding-down device for a machining head of laser machining machines, which holding-down device has a contact device sliding over a workpiece surface and a fastening device, and which is characterized in that the fastening device and the contact device are connected to one another by means of a connecting device which is elastically compressible at least in the vertical direction, and in that the fastening device can be detachably mounted on the machining head. Workpiece holders are wear parts. It is therefore advantageous that the hold-down device according to the invention can be arranged interchangeably on a processing head of a laser processing machine.Further features and advantages of the invention are evident from the description, the claims and the drawing. According to the invention, the features mentioned above and those set out further below can each be used individually or together in any desired suitable combinations. The embodiment shown and described is to be understood as the only possibility of configuration. Rather, it is exemplary in nature for purposes of describing the invention.DETAILED DESCRIPTION OF THE INVENTION AND DRAWING FIG. 1 is a perspective view of a hold-down device for a laser machining head.FIG. 1 shows a holding-down device 10 for a processing head of a laser processing machine, which is not shown in any more detail here. The hold-down device 10 has an annular fastening device 11 with the aid of which the hold-down device 10 can be fastened to the outer periphery of a processing head. The hold-down device 10 also has an annular contact device 12 which is provided with bristles 13 on its underside. The holding-down device 10 is moved by the machining head over the surface of a workpiece, not shown here. The bristles 13 of the contact device 12 ensure that the workpiece surface is not damaged. In addition, they shield the laser beam emerging from the machining head in the radial direction.Between the contact device 12 and the fastening device 11 a connecting device 14 is arranged which in the example shown is formed by a plurality of force elements 15-here leaf springs. The force elements 15 are distributed uniformly over the circumference of the fastening device 11 and the contact device 12. They allow gimbal movement of the contactor 12 as it is lifted by a wavy workpiece. The connecting device 14 can thereby absorb in particular vertical movements of the contact device 12, so that these movements are not forwarded to the fastening device 11. In this way, a safety shutdown of the laser beam and / or damage to the machining head during the machining of wavy workpieces can be avoided.The configuration of the force elements 15 as leaf springs is merely exemplary. Coil springs, hydraulic or pneumatic cylinders, rubber elements or other elastically deformable elements could also be used.

Claims

Machining head for guiding a laser beam of a laser machining machine, having a holding-down device (10), which surrounds the laser beam in a ring shape, for a workpiece to be machined and has a contact device (12) which slides over the workpiece surface and is fixed to the laser machining head by means of a fastening device (11), characterized in that the fastening device (11) and the contact device (12) are connected to one another by means of a connecting device (14) which is elastically compressible at least in the vertical direction.Machining head according to claim 1, characterised in that the connecting device (14) has a plurality of elastic force elements (15).Machining head according to claim 2, characterised in that the force elements (15) are leaf springs, helical springs, hydraulic or pneumatic cylinders or rubber elements.Machining head according to one of the preceding claims, characterized in that the connecting device (14) is designed in such a way that it permits passive gimbal movement of the contact device (12) by action of the workpiece to be machined.Machining head according to one of the preceding claims, characterized in that the contact device (12) is provided on its underside with flexible bristles (13).Machining head according to one of the preceding claims, characterized in that the contact device (12) and the fastening device (11) are of annular design.Machining head according to one of the preceding claims, characterized in that the fastening device (11) is arranged on the machining head so as to be vertically displaceable.Machining head according to claim 7, characterised in that the vertical position of the fastening device (11) is monitored by a sensor device connected to a controller of the laser machining head.Machining head according to one of the preceding claims, characterized in that the holding-down device (10) is surrounded by a cylindrical laser shielding device.Machining head according to claim 9, characterised in that the laser shielding device has a plurality of tab-shaped shielding elements arranged adjacent to one another in the circumferential direction of the holding-down device (10).Hold-down device (10) for a machining head of laser machining machines, which has a contact device (12) sliding over a workpiece surface and a fastening device (11), characterized in that the fastening device (11) and the contact device (12) are connected to one another by means of a connecting device (14) which can be elastically compressed at least in the vertical direction, and in that the fastening device (11) can be detachably mounted on the machining head.

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