Method for low energy separation of a glass ribbon
Disclosed is a method of separating a glass sheet from a moving glass ribbon, wherein the glass ribbon comprises thickened bead portions. The method comprises weakening the bead portions of the ribbon using laser-initiated ablation at the bead portions to overcome the potential for uncontrolled cracking through the bead portion.
1. A method of separating and removing a glass sheet from a ribbon of glass comprising:
producing a glass ribbon in a down draw process, the glass ribbon comprising a viscous liquid portion and an elastic solid portion, the elastic solid portion of the glass ribbon further comprising a central portion comprising a first major surface and a second major surface which are substantially parallel and two edge portions adjacent to either side of the central portion, each edge portion comprising a first major surface and a second major surface coinciding with the first and second major surfaces of the central portion, the first and second major surfaces of the edge portions extending longitudinally along a length of the ribbon, and wherein the first major surface and the second major surface of each edge portion are non-parallel;
irradiating the first major surface of an edge portion of the two edge portions with a laser beam from a first laser at a first position, the laser beam being a pulsed laser beam that forms a first laser spot on the first major surface of said edge portion, the pulsed laser beam forming a defect channel through at least a portion of the thickness of the glass ribbon in the vicinity of said edge portion;
traversing the laser in a direction perpendicular to an outer edge of said edge portion and repeating the irradiating with the first laser to form a plurality of discrete defect channels in the edge portion along a line perpendicular to the outer edge;
scoring the central portion of the glass ribbon, wherein a score line formed by the scoring aligns with the line of defect channels;
and
separating the glass ribbon along the score line.
2. The method according to claim 1 , wherein the comprises using a second laser to form the score line.
3. The method according to claim 2 , wherein the scoring comprises contacting the central portion with a scoring member.
4. The method according to claim 1 , wherein the separating comprises bending the glass ribbon to form a tensile stress across the first major surface of the central portion that intersects with the score line.
5. The method according to claim 1 , wherein a wavelength of light from the pulsed laser beam is in a range from about 355 nm to about 532 nm.
6. The method according to claim 1 , wherein a repetition rate of the pulsed laser beam is in a range from about 10 kHz to about 200 kHz.
7. The method according to claim 1 , wherein a pulse duration of the pulsed laser beam is equal to or less than about 25 ns.
8. The method according to claim 1 , wherein the first laser is a Nd:YAG or Nd:YVO4 laser.
9. The method according to claim 2 , wherein the second laser is a CO 2 laser.
10. The method according to claim 1 , wherein the glass ribbon is continuously moving.
11. The method according to claim 1 , wherein the down draw process is a fusion down draw process.