Electric heating – Metal heating – By arc
Reexamination Certificate
1999-11-04
2001-10-30
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121780, C074S089200
Reexamination Certificate
active
06310317
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to laser cutting machines and more particularly to a laser cutter where the laser cutting head is mounted to the underside of a cross beam and how the laser beam generated from the laser beam generator can be accurately conveyed to such cutting head.
BACKGROUND OF THE INVENTION
Most laser cutting machines of the gantry type utilize bellows type covers for protecting the mechanism that supports and drives the laser cutting head carriage. One such system is disclosed in U.S. Pat. No. 5,854,460. However, the use of such bellows type cover for enclosing a laser beam guide tends to have detrimental effects on the accuracy of the laser beam. This is due to the fact that such bellows type cover in essence acts the same as an accordion so that, when the laser head carriage moves, some portions of the cover would compress while other portions of it would expand. And when that happens, a vacuum is created inside the beam guide so that dirt and dust tend to be sucked into the beam guide. Such dirt and dust then create a disturbance to the laser beam, and therefore affect its accuracy.
To overcome such shortcomings, a new type of beam guide that allows the laser cutting head to freely move and yet at the same time not create any vacuum is needed.
SUMMARY OF THE INVENTION
The laser beam guide of the instant invention has a guide tube that extends from the laser beam generator. An open channel is formed on the side of the guide channel that faces the carriage that carries the laser cutting head movably mounted to the underside of the cross beam of the laser machine. The channel opening is covered by a sheet of flexible non-magnetic ferrous or synthetic material that includes for example a stainless steel metallic plate or a Teflon-fiberglas roll or mat, respectively. The cover sheet is movably fitted to an upper bracket and a lower bracket mounted to the upper edge and the lower edge, respectively, of the opening of the tubular beam guide, with each end of the cover sheet forming a coil that is spring biased at the respective ends of the tubular guide. An aperture is formed approximately at the middle portion of the cover sheet, so that, as the cover sheet is slidably moved along the tubular guide, the aperture is moved therealong.
A connection mechanism, preferably in the form of a tube or conduit, connects the aperture at the cover plate with the laser cutting head mounted to the underside of the cross beam of the laser cutter machine. Since the cross beam is positioned in parallel to the tubular beam guide, as the laser cutting head is moved along the longitudinal axis of the cross beam, by means of the conduit that connects it to the aperture of the cover sheet, the cover sheet, and particularly the aperture thereof, is moved in lockstep with the laser cutting head.
A reflecting mechanism such as for example a laser mirror is positioned inside the tubular guide so as to move along the path of the laser beam. The reflective mirror is further positioned relative to the aperture so that as it moves along the inside of the tubular guide, it intercepts the laser beam and reflects it through the conduit to the laser cutter head. Additional reflecting mechanisms in the laser cutting head redirect the thus reflected laser beam to the tip of the cutting head so as to fabricate a sheet of material placed thereunder on the worktable of the laser cutting machine.
Inasmuch as the non-magnetic ferrous material or non-magnetic synthetic material cover sheet is slidably moved along the open channel of the tubular guide with the respective end coils thereof providing any additional or taking in any excess of the cover sheet, a stable environment is maintained within the inside of the tubular guide. Thus, no vacuum is created inside the tubular guide by the movement of the cover sheet. Accordingly, no dirt or dust is suctioned into the tubular guide to create any disturbance to the laser beam. The laser beam reflected by the mirror to the laser head accordingly stays focused, with no substantial loss of power.
It is therefore an objective of the present invention to provide a guide for a laser beam that does not create any vacuum as the laser beam is being reflected out of the beam guide to a laser cutting head.
It is another objective of the present invention to provide a laser beam guide that is readily adaptable to be used with a laser cutting head that is movably mounted to the underside of a cross beam of a laser cutting machine.
REFERENCES:
patent: 3612814 (1971-10-01), Houldcroft
patent: 4973819 (1990-11-01), Thatcher
patent: 5051558 (1991-09-01), Sukhman
patent: 5854460 (1998-12-01), Graf et al.
patent: 5915823 (1999-06-01), Simon
patent: 1 010 446 (1998-08-01), None
Heinrich Samuel M.
Lillbacka Jetair Oy
Woo Louis
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