Patent GB-777212-A (GB)
Title: Improvements in or relating to apparatus for both severing and providing weakened tear zones in flexible strips
Inventor: WESTON BENNETT
IPC: B65B61/02
Filed: 1952-05-26
Abstract: 777,212. Wrapping-machines. IDEAL PACKAGINGS, Ltd. Aug. 26, 1953 [May 26, 1952], No. 34957/55. Divided out of 777,211. Class 94(1). [Also in Group VIII] Apparatus for providing weakened tear zones in a package strip and severing the strip into lengths each containing one or more weakened tear zones, comprises means for continuously feeding the strip longitudinally and common cutter means which engage the moving strip at intervals and are arranged to penetrate the strip less or more according to whether they form a weakened tear zone or effect a severance. As shown, applied to the machine described in Specification 777,211, the strip of interconnected packages issuing from the sealing rolls passes between fixed blades 79 and a reciprocable serrated blade 80 carried by a frame 74, 75 which is freely mounted on a spindle 78 for oscillation by a cam-operated linkage (not shown). The lower edge of the blade 80 is secured to two strips 81, whose ends are slidable in grooves in the frame, and its upper cutting edge is normally protected by two strips 82 whose ends are also slidable in the grooves and which are connected to the strips 81 by springs 83 which yield to allow the blade 80 to enter between the blades 79. Further springs 84 passing through slots 85 in one of the blades 79 are provided for ejecting waste. The blade 80 is reciprocated by rods 88 connected between the strips 81 and cranks 86, 87 secured to the spindle 78, the crank 86 being formed with a slot 94 which receives a pin 95 on the left-hand end of a lever 92 pivoted at 93 to a lever 91 having its left-hand end resting on the spindle 78 and its right-hand end pivoted on a rod 90 connecting extensions 89 of the frame. A stop 96 normally prevents upward movement of the right-hand end of lever 92, so that as the frame rocks counter clockwise the lever 91 actuates the lever 92 to cause the cranks to rock upwardly relative to the frame and the blade 80 is moved upwardly far enough to form a line of perforations between adjacent packages in the strip as it is moved to the left at the same speed as the strip. The left-hand end of the lever 91 carries an adjustable screw 97 arranged to engage a stop on a spring- loaded ratchet wheel 99 which is rotated stepby-step by a pawl 100 pivotally connected to an arm 102 secured to the frame and oscillatable about the spindle 78. A retaining pawl 103 normally prevents return movement of the wheel under the action of its spring. After a given number of oscillations of the frame determined by adjustment of the stop on the wheel, the stop is positioned beneath the screw and acts as a fulcrum for the lever 91 during the next oscillation. The blade is therefore moved further upwardly to sever the strip completely. At the end of the counter clockwise movement of the frame the pawl 100 falls into a notch 104 in the wheel and a recess therein mates with a projection 104a on the retaining pawl 103 so that when the frame is rocked clockwise, both pawls are disengaged and the wheel returns to its starting position. The stop 96 is carried by an arm 105 which is acted on by a spring 107 but normally retained in the position shown by the engagement of a notch in the underside of the stop with the upturned extremity of the lever 92. When the frame reaches the end of its counter clockwise movement, it engages the bent end 108 of a slidable bar 109 which is coupled to a lever 111 engaging a pin 113 on the stop. The stop is thus moved to the right to permit the right-hand end of the lever 92 to move downwards and the blade 80 is returned substantially instantaneously to its starting position and remains clear of the package strip during the clockwise movement of the frame. Reference has been directed by the Comptroller to Specification 551,569. [Group VIII].