| 摘要 |
The disadvantage of laser machining technique became evident with respect to a penetrating machining and is characterized by the fact, that cutting metals having a thickness of more than 2 to 3 cm is not possible Said disadvantage, clearly identified by the present invention, is due to the lack of phase shift control. The invention teaches that said phase shift is inevitable when the focalized laser beam has to traverse a thickness L during machining and that consequently said phase shift has to be systematically confined by affecting the focalization parameter bo defined by: bo=p (Do/2f)<SUP>2</SUP> // wherein Do is the outer diameter of the incident laser beam and ? represents its wavelength and f is the focal length FO of the system consisting of incident laser beam and focalization device, wherein F is the focal point. For said purpose, the present invention suggest the use of the method for machining by focal area laser beam characterized by fo=bo-L<1.4 radian. L represents the area separating the two orthogonal planes P1 and P2 at the focal optical axis FO, framing the focal point F between them. The focal space P1P2 of the geometrical width L subjected to the condition of specific phase limitation fo=bo-L<1.4 rd (and preferably fo=1 rd) is called focal area. The method is such that in penetrating machining, for example when cutting of a metal plate of a width EP5 is performed, it is supposed that L~Ep and the plate to be cut is positioned such that its two surfaces coincide with planes P1 and P2 and the required power P is calculated according to the equation: 25 V(L)V[10,6-10<SUP>-4</SUP> Ix]- P = 0,81 pKTo /e, subsequently multiplied with 1 J and 1.4, wherein K represents the conductivity and e the absorption coefficient of the metal and T its fusion temperature. In non-penetrating machining, such as surface treatment, the method is such that L is calculated according to the equation: pA<SUP>2</SUP>=(ß /2)<SUP>2</SUP>. (?-L /fo wherein A is the half geometric diameter of the impact site and ß=3.2 rd represents its corresponding half optical diameter; and the surface which is to receive the treatment is positioned between P1 and P2 and the required power P is calculated according to the equation: 32 //(L) /[10,6-10-4 /?] P=0,72 pKT /e wherein T is the temperature at which machining is to be carried out. The method is such that bo is part of the interval ]0; 6.25 ]; and the smallest focal limit is at least equal to (1.4 /6.25=)0,224 centimeters. |
