ES374830A1 - Strap feeding and tensioning system - Google Patents

Abstract

In an apparatus for looping a strap 4 around an article 10 the strap is drawn from a supply roll 2 passed by a guide 28 round a feed wheel 26 and associated pinch rolls 27, 29 to a second guide 30 which leads it freely round a tension wheel 32 and into a guide 38 and past a gripper 40 the strap then being fed through an opening in a stationary cutter 42, under a facing gate 46, and around a guide 47 which loops it around the article 10 so that the leading end overlaps the main part of the strap. The strap is finally directed over the stationary cutter 42 and over the facing gate 46 to engage a stop 52 whereupon the strap, which is continuously fed by the feed wheel 26 driven by a motor 12, expands outwardly within a chamber 53 adjacent the tension wheel 32 to pivot on arm 57 which initiates the switching-off of the motor 12. De-energizing the motor 12 activates a solenoid not shown which, by means of a linkage 58, raises the gripper 40 to hold the leading end of the strap 4 against a vibrator 50. After tension has been drawn on the strap, by reversing the direction of rotation of the feed and tension wheels 26, 32 and locking them to secure the tension, the motor 12 is available to move a toggle plate 104 which, by means of slots 112, 138 and toggle links 114, 116 and 132, 134, moves associated members 126, 142 which carry respectively grippers 128, 144 to move the overlapped strap portions into engagement with the base of the vibrator 50. The gripper 128 is raised before the gripper 144 to remove, through a linkage, the face gate 46 from between the overlapped strap portions, the gripper 144 being raised slightly later and releasing the gripper 40 a sharp corner 146 co-operating with the stationary cutter to sever the strap, immediately after the tension has been released by moving the pinch rolls 27, 29 outwardly away from the feed wheel 26 to ensure a straight square, cut. The vibrator 50 is then actuated to bond the overlapping portions of the strap together by friction, the motor 12 then being reversed to pull down the grippers 128, 142, replace the face gate 46, and return the pinch rolls 27, 29 into driving relationship with the feed wheel 26 so that the machine is ready for another feeding. The feed wheel 26 is driven in the feeding direction by a shaft 22 which is rotated clockwise by a feed and tension gear 18 which acts through a pinion and slip clutch 24 and which meshes with a pinion 17 on a shaft 22 driven by the motor 12 through a slip clutch, not shown. To tension the strap 4 after its free end has been clamped by the gripper 40, the gear 18 is rotated in a clockwise direction so that the wheels 26, 32 are correspondingly rotated in their reverse directions, the wheel 26 rotating faster than the wheel 32, which is driven through an over-running clutch 36, until the clutch 20, 24 slips, the final tension being drawn by the wheel 32 whereupon the clutch in the drive from the motor 12 slips. The tension is held by locking the shaft 22. The pinch rolls 27, 29 are mounted on crank arms 150, 152 which are carried by a linkage 158, 160 and are urged towards the feed wheel 26 by a spring 31, the linkage being expanded, against the action of the spring 31, by a lever arm 170 which is actuated by a cam wheel 168 when the toggle linkage 134 is raised to operate the gripper 144.