Device to clamp logs during the cut thereof and sawing machine comprising said device
The device comprises a log advancing path and a set of jaws in the form of double four-bar linkage, with an adjusting mechanism to adjust the position of the jaws according to the diameter of the logs to be cut.
1. A device to clamp a log (L) to be cut, comprising a log advancing path and, on each side of an intermediate plane (C-C) parallel to the advancing path, a set of jaws, each set comprising a first jaw ( 25 ) and a second jaw ( 27 ), the first jaw ( 25 ) being hinged to a fixed structure ( 29 ) around a first pivoting axis (A 25 ) and the second jaw ( 27 ) being hinged to the fixed structure ( 29 ) around a second pivoting axis (A 27 ); wherein each first jaw ( 25 ) and second jaw ( 27 ) are joined together by means of a connecting rod ( 41 ) and form, with said connecting rod ( 41 ) and the fixed structure ( 29 ), a four-bar linkage, the first jaw ( 25 ) and the second jaw ( 27 ) forming a respective first rocker and a respective second rocker of the four-bar linkage; wherein the first rocker is hinged to a first end of a respective rod-strut ( 33 , 35 ); and wherein the rod-strut ( 33 ; 35 ) is movable in order to make the respective four-bar linkage oscillate and to cause the adjustment of the jaws position according to the diameter of the log to be cut.
2. Device according to claim 1 , wherein the first rocker extends, thus forming an arm ( 31 ), through which the first rocker is hinged to the rod-strut.
3. Device according to claim 1 , wherein the rod-strut is hinged, at a respective second end, to a movable member ( 32 ; 37 ; 37 A, 37 B), the motion of the movable member ( 32 ; 37 ; 37 A, 37 B) causing oscillation of the respective four-bar linkage.
4. Device according to claim 3 , wherein the movable member ( 37 ; 37 A; 37 B) moves according to a direction substantially orthogonal to the advancing path of the logs (L).
5. Device according to claim 1 , wherein each respective rod-strut ( 33 ; 35 ) are hinged, at a respective second end, to a common movable member ( 32 ; 37 ; 37 A, 37 B), having a movement that causes symmetrical oscillation of each respective four-bar linkage.
6. Device according to claim 1 , further comprising an actuating mechanism to control an opening and closing movement of the first jaw ( 25 ) and of the second jaw ( 27 ), synchronously with forward movement of the log on the log advancing path.
7. Device according to claim 6 , wherein the actuating mechanism comprises a lengthening and shortening mechanism for at least one respective rod-strut ( 33 , 35 ).
8. Device according to claim 7 , wherein the lengthening and shortening mechanism comprises a cylinder-piston actuator.
9. Device according to claim 6 , wherein the actuating mechanism comprises a movable element ( 36 ), to which at least one respective rod-strut is hinged.
10. Device according to claim 1 , wherein at least one respective rod-strut ( 33 ; 35 ) has variable length.
11. Device according to claim 1 , wherein each respective rod-strut ( 33 , 35 ) is fastened to a movable element ( 32 ; 36 ; 37 X) associated with an actuating member to control an opening and closing movement of the first jaw ( 25 ) and of the second jaw ( 27 ), synchronously with the forward movement of the log.
12. Device according to claim 1 , wherein each connecting rod ( 41 ) is hinged to the respective arm ( 31 ) in a position intermediate between the first pivoting axis (A 25 ), around which the first jaw ( 25 ) is hinged to the fixed structure ( 29 ), and a pivoting axis ( 31 B), around which the arm ( 31 ) is hinged to the respective rod-strut ( 33 , 35 ).
13. Device according to claim 12 , wherein each second jaw ( 27 ) is provided with a small arm ( 39 ), to which the respective connecting rod ( 41 ) is hinged.
14. Device according to claim 1 , each first jaw ( 25 ) and second jaw ( 27 ) of the set of jaws further comprises a third jaw ( 51 ), stationary with respect to the fixed structure ( 29 ).
15. Device according to claim 14 , wherein each first jaw ( 25 ) is arranged between the third jaw ( 51 ) and the second jaw ( 27 ), the respective third jaw ( 51 ) of each set of jaws being adjacent to each other in a position below the log advancing path.
16. Device according to claim 1 , wherein each second jaw comprises an elongation symmetrically extending above a respective first jaw and around the advancing path.
17. A saw machine ( 1 ) comprising the device of claim 1 to clamp a log, said saw machine for cutting said log (L) comprising a log of wound web material, said saw machine further comprising: a cutting blade ( 11 ) configured and controlled to cut the log according to a cutting plane (T-T) orthogonal to the advancing path for the log (L), said saw machine further comprising log feeding members ( 7 ), having movements synchronized with movement of the cutting blade ( 11 ) to advance the log on the advancing path; and, along said advancing path, said device to clamp the log (L) arranged adjacent to the cutting plane (T-T) of the cutting blade ( 11 ).
18. Saw machine according to claim 17 , comprising, for said log advancing path, a second device to clamp the log, wherein the first device and the second device the log (L) are arranged on opposite sides of the cutting plane (T-T).