Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/70—Auxiliary operations or equipment
  • B23K26/702—Auxiliary equipment
  • B23K26/707—Auxiliary equipment for monitoring laser beam transmission optics
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/70—Auxiliary operations or equipment
  • B23K26/702—Auxiliary equipment

Definitions

• the present invention relates to a method and an apparatus for checking the condition of a protective glass which is arranged between the workpiece and the laser optics in a laser machining system in which the laser beam, or any other substantially coaxial radiation, is arranged to pass through the glass before it is focused on the workpiece.
• protective glasses In order to protect the optical components in a laser machining system, for instance in a laser welding or engraving equipment, it is previously known to use protective glasses. Such protective glasses are then mounted between the laser optics and the object (workpiece) to be machined and prevents dirt and dust particles produced at the machining from entering into the laser optics.
• the incident laser beam also is the working, machining, beam it should be understood that such absorption and scattering of the beam is unsatisfactory as the power density of the focused beam is reduced.
• This is a disadvantage especially in a laser welding system as the welding capacity then is reduced.
• it is also a disadvantage in for instance a laser engraving system of the type illustrated in the Swedish Patent 9403349-5 in which small complex engraving patterns are made by means of the laser beam. If the beam is unsharp due to the scattering effect, the good quality of the pattern or script produced by the laser beam can not be maintained.
• thermo detector arranged to sense (detect) the temperature of the protective glass itself or the glass support- ing parts, specifically the mechanical protective glass holder.
• the thermal detector is combined with an optical detector of a previously known type, so that both types of dirt contamination can be controlled simultaneously.
• Figure 1 illustrates a known optical protective glass control arrangement in connection with laser machining
• FIG. 2 illustrates schematically an arrangement according to the invention
• Figure 3 illustrates a so-called sensor card with an opti- cal as well as a thermal detector
• Figure 4 illustrates more in detail the sensor card mounted in connection with the edge of the protective glass.
• FIG 1 it is illustrated schematically a focusing optical arrangement, symbolised by a lens 1, which concentrates the incident laser radiation on a workpiece 2.
• a lens 1 which concentrates the incident laser radiation on a workpiece 2.
• It can be a welding system, an engraving system like the one illustrated in SE 9403349-5, a cutting system or any other laser machining system.
• dirt and dust particles are produced from the workpiece during the machining process.
• a protective glass plate 3 is arranged between the workpiece 2 and the focusing lens 1.
• the protective glass plate is mounted in a holder 4 and it has a circular peripheral edge side.
• the dirt, dust and smoke particles 5 that are produced during the machining process are instead gathered on the protective glass surface 3.
• the particles can not enter into the more delicate optical system, but the disadvantage with such a system is that the particles are gradually accumulated on the glass surface and are causing an undesired scattering and absorption of a part of the incident laser radiation 6. Therefore, a photode- tector 8 is arranged at the edge side of the protective glass to sense the scattered radiation 7 on the glass edge 9, and which radiation is an indicia of the contamination layer on the protective glass.
• the photodetector senses the amount of radiation scattered by particles sticked on the protective glass surface. When the detector signal has reached a certain level, this is an indication that it is time to replace the protective glass. This means that the condition of the protective glass with respect to such particles which generate a scattered radiation can be controlled continuously during the machining process.
• a thermal detector 10 is also arranged in connection with the protective glass in order to measure the temperature of the protective glass and the surrounding mechanical parts. When the detector signal has reached a certain level this is an indication that it is time to replace the protective glass.
• the detector 10 itself could be of a known type and will not be described in any detail here.
• the thermal detector 10 is mounted together with the optical detector 8 on a sensor card 11, see figure 3.
• the sensor card 11 is mounted directly onto the mechanical part attaching the protective glass in the holder 4. This means that a good thermal contact is obtained with the holder 4, see figure 4.
• the optical detector 8 is mounted on the uppermost part of the card so that it is viewing the edge of the protective glass 3 through an optical window 13, i.e. analogous to what has been described in SE 97.00196-0.
• the card is attached to the holder 4 of the protective glass by means of a screw, bolt 14 or the like.
• the detectors are, by means of a contacting device 12 and conduits 15, connected to an electronic signal processing circuit, which electronic signal processing circuit in turn is cou- pled to indicating and display means (not shown).
• both the electronic signal processing circuit and the indicating and display means could be of a type which is known per se, they will not be described in any detail here. As soon as the signals exceed a certain, predetermined value, this is indicated by means of an audio

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Laser Beam Processing (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20411390

Family Applications (1)

Country Status (4)

Cited By (11)

Families Citing this family (6)

Citations (3)

• 1998
  • 1998-05-20 SE SE9801780A patent/SE512097C2/sv not_active IP Right Cessation
• 1999
  • 1999-04-13 WO PCT/SE1999/000592 patent/WO1999059762A1/en not_active Application Discontinuation
  • 1999-04-13 EP EP99925508A patent/EP1146986A1/en not_active Withdrawn
  • 1999-04-13 JP JP2000549415A patent/JP2002515341A/ja active Pending

Patent Citations (3)

Non-Patent Citations (1)

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