Method and apparatus for cutting glass ribbon
A process and apparatus for cutting a continuous glass ribbon involving the use of edge restrainers such as suction cups and clamps connected to an actuator of a robot tooling through a flexible linkage capable of reciprocal motion in the direction of the ribbon velocity. The use of the flexible linkage reduces peak pulling-force when the glass ribbon is pulled or pushed laterally to during bending and separation along a pre-formed score-line. The invention can be advantageously used in the bottom of the draw of a vertical down-draw forming process.
1. A process for making a target glass sheet, comprising the following steps:
(A) providing a precursor glass ribbon comprising an elastic portion, the elastic portion having a thickness T 1 , a width W 1 , a first major surface S 1 having a target point TP traveling with a velocity V 1 , a second major surface S 2 opposing S 1 , S 1 comprising a first peripheral region PR 1 , a second peripheral region PR 2 and a first center region CR 1 ; S 2 comprising a third peripheral region PR 3 , a fourth peripheral region PR 4 and a second center region CR 2 , where PR 1 is in opposing relation to PR 3 , PR 2 is in opposing relation to PR 4 , and CR 1 is in opposing relation to CR 2 ;
(B) engaging a first pair of edge rollers FR 1 having a substantially stationery rotation axle relative to the earth with PR 1 and PR 3 at a first edge roller position;
(C) engaging a second pair of edge rollers FR 2 having a substantially stationery rotation axle relative to the earth with PR 2 and PR 4 at a second edge roller position;
(D) contacting a first edge restrainer ER 1 traveling with a velocity substantially equal to V 1 with at least one of PR 1 and PR 3 at a first edge restrainer location downstream of a line SL passing through the target point TP substantially perpendicular to V 1 ;
(E) contacting a second edge restrainer ER 2 traveling with a velocity substantially equal to V 1 with at least one of PR 2 and PR 4 at a second edge restrainer location downstream of the line SL;
(F) forming a transverse score-line along the line SL on S 1 upstream of the locations of the first edge restrainer and the second edge restrainer; and
(G) applying to the elastic portion a breaking force F 1 perpendicular to the elastic portion below the score-line and a supporting force F 2 above the score-line in a direction opposite to that of F 1 , the direction of F 1 being pointing from S 1 to S 2 , thereby breaking the elastic portion along the score-line to obtain the target glass sheet below the score-line; wherein during step (G), a maximal force F 3 in the same direction of V 1 other than gravity is applied to the elastic portion below the score-line, and 0≦F 3 ≦400 newton; and
wherein before step (G), a step (G-1) is carried out:
(G-1) connecting ER 1 and ER 2 with an actuator through a flexible linkage capable of reciprocal motion in a direction parallel to V 1 essentially free of resistance.
2. A process in accordance with claim 1 , wherein V 1 is essentially parallel to the gravity vector.
3. A process in accordance with claim 1 , wherein 0≦F 3 ≦300 newton.
4. A process in accordance with claim 1 , wherein F 3 is applied to the glass ribbon by ER 1 and/or ER 2 .
5. A process in accordance claim 1 , wherein a nosing contacts S 2 in the vicinity of the score-line during steps (F) and (G).
6. A process in accordance with claim 5 , wherein the nosing is a flat nosing bar extending from PR 3 to PR 4 contacting S 2 covering the score-line during step (G).
7. A process in accordance with claim 5 , wherein during step (G), the nosing contacts S 2 in the vicinity of the score-line, and the nosing is adjusted to conform to the curvature of S 2 without substantially deforming the curvature of S 2 .
8. A process in accordance with claim 1 , wherein ER 1 and ER 2 are selected from suction cups, clamps and rollers.
9. A process in accordance with claim 8 , wherein ER 1 , ER 2 and a nosing are fixed on a platform capable of reciprocal vertical motion.
10. A process in accordance with claim 1 , wherein the precursor glass ribbon further comprises a visco-elastic zone traveling with the velocity V 2 within 10 meters above the score-line, where V 2 is parallel to V 1 .
11. A process in accordance with claim 1 , wherein the ratio W 1 /T 1 of the elastic zone is at least 1000.
12. A process for making a target glass sheet, comprising the following steps:
(A) providing a precursor glass ribbon comprising an elastic portion, the elastic portion having a thickness T 1 , a width W 1 , a first major surface S 1 having a target point TP traveling with a velocity V 1 , a second major surface S 2 opposing S 1 , S 1 comprising a first peripheral region PR 1 , a second peripheral region PR 2 and a first center region CR 1 ; S 2 comprising a third peripheral region PR 3 , a fourth peripheral region PR 4 and a second center region CR 2 , where PR 1 is in opposing relation to PR 3 , PR 2 is in opposing relation to PR 4 , and CR 1 is in opposing relation to CR 2 ;
(B) engaging a first pair of edge rollers FR 1 having a substantially stationery rotation axle relative to the earth with PR 1 and PR 3 at a first edge roller position;
(C) engaging a second pair of edge rollers FR 2 having a substantially stationery rotation axle relative to the earth with PR 2 and PR 4 at a second edge roller position;
(D) contacting a first edge restrainer ER 1 traveling with a velocity substantially equal to V 1 with at least one of PR 1 and PR 3 at a first edge restrainer location downstream of a line SL passing through the target point. TP substantially perpendicular to V 1 ;
(E) contacting a second edge restrainer ER 2 traveling with a velocity substantially equal to V 1 with at least one of PR 2 and PR 4 at a second edge restrainer location downstream of the line SL;
(F) forming a transverse score-line along the line SL on S 1 upstream of the locations of the first edge restrainer and the second edge restrainer; and
(G) applying to the elastic portion a breaking force F 1 perpendicular to the elastic portion below the score-line and a supporting force F 2 above the score-line in a direction opposite to that of F 1 , the direction of F 1 being pointing from S 1 to S 2 , thereby breaking the elastic portion along the score-line to obtain the target glass sheet below the score-line; wherein during step (G), a maximal force F 3 in the same direction of V 1 other than gravity is applied to the elastic portion below the score-line, and 0≦F 3 ≦400 newton; and
wherein:
step (A) further comprises the following step (A1):
(A1) measuring the velocity V 1 substantially continuously; and
in steps (D) and (E), the velocities of ER 1 and ER 2 are synchronized to V 1 substantially continuously.
13. A process in accordance with claim 12 , wherein V 1 is essentially parallel to the gravity vector.
14. A process in accordance with claim 12 , wherein 0≦F 3 ≦300 newton.
15. A process in accordance with claim 12 , wherein F 3 is applied to the glass ribbon by ER 1 and/or ER 2 .
16. A process in accordance claim 12 , wherein a nosing contacts S 2 in the vicinity of the score-line during steps (F) and (G).
17. A process in accordance with claim 16 , wherein the nosing is a flat nosing bar extending from PR 3 to PR 4 contacting S 2 covering the score-line during step (G).
18. A process in accordance with claim 16 , wherein during step (G), the nosing contacts S 2 in the vicinity of the score-line, and the nosing is adjusted to conform to the curvature of S 2 without substantially deforming the curvature of S 2 .
19. A process in accordance with claim 12 , wherein ER 1 and ER 2 are selected from suction cups, clamps and rollers.
20. A process in accordance with claim 19 , wherein ER 1 , ER 2 and a nosing are fixed on a platform capable of reciprocal vertical motion.