Patent GB-818076-A (GB)
Title: Web rewinding machine
IPC: B65H18/26
Filed: 1956-04-04
Abstract: 818,076. Feeding webs. CAMERON MACHINE CO. April 4, 1956 [April 4, 1955], No. 10253/56. Class 100(1) In a web rewinding machine wherein a . web is drawn from a supply roll 122 (Fig. 10) and passes via a roll 125 on to a contact drum 29 against which longitudinal slitting is effected by a plurality of wheels 126 and from the drum 29 on to a front rewind shaft 21 and rear rewind shaft 22 means are provided for (a) counterbalancing the static weight of the rewind shafts and the supporting arms, (b) counterbalancing the static weight of the web rolls as they build up on the rewind shafts and (c) counterbalancing the web tension reaction caused by the driving of the rewind shafts. System for counterbalancing the static weight of the rewind shafts and their supporting arms. The shafts 21 and 22 are supported by arms 23, 24 and 26, 27 respectively, (Fig. 1) the arms 23, 24 being pivotally mounted about a shaft 25 and the arms 26, 27 about a shaft 28. The weight of the first rewind shaft and arms is counterbalanced by springs 30 and 31 coiled about a shaft situated below the shaft 25 but operatively connected thereto by suitable linkage whereby the torque of the springs 30, 31 is communicated to the shaft 25. In Fig. 1 the springs 30 and 31 are diagrammatically shown as coiled about the shaft 25. The weight of the rear rewind shaft and arms is counterbalanced by means of springs 42 and 43 the inner extremities of which are secured to sleeves angularly adjustable about the shaft 28. System for counterbalancing the web material weight on the rewind rolls. The counterbalancing system for the rear rewind shaft supporting arms 26, 27 comprises pneumatic cylinders 53, 54 operatively connected to the arms 26 and 27 respectively by means off piston rods 57 and 58. Pneumatic pressure is directed to the cylinders under the control of a control valve 59 and which in turn is influenced by (a) the angular position of the arms 26 and 27 and (b) the sum in inches of the rewind! roll widths on the rewind shaft. The valve 59 by means of a rod 60, is influenced by a cam 61 which is angularly shiftable in response to angular movement of the arms 26, 27. The cam 61 is such that it moves, in the direction of the arm 63, a ramp element 64 which is pre-adjusted in slope in accordance with the sum in inches of the rewind roll widths. For this purpose a scale 65 and pointer 66 are provided. Pneumatic pressure is obtained from a main supply line 80 and is conducted to the cylinders 53 and 54. for the purpose of either raising for lowering the rewind shaft 22 by means of a main valve 81 controlled by a lever 82. The valve 59 is connected to a conduit 85 for supplying the cylinders with air pressure to raise the shaft 22 through a valve 97 which isolates the valve 59 when the lever 82 is in either the "raise" or "lower" position. With the lever 82 in the "run" position, however, a pilot valve 98 is operated to open the valve 97 thus allowing air pressure to pass to the cylinders 53, 54 via conduit 95, valve 59, conduit 96a, valve 97, conduit 96b and conduits 85, 86 and 87. The amount of air pressure applied is controlled by the valve 59 which is in turn controlled by the angular position of the arms 26, 27 and the weight of the web roll. With the lever 82 in the "run" position the main valve 81 is closed. Provision is made for introducing a hand controlled pressure acting counter to the pressures coming from the valve 59. For this purpose a hand controlled valve 100 is provided which supplies pressure to the conduit 91 via a valve 103 similar to, and operative under the same conditions as, the valve 97. A smilar counterbalancing system is provided for the front rewind shaft. A pressure is also applied axially of the rewind shafts 21 and 22 by means of pressure sleeves 105 actuated by bell crank levers 108 operated by the pistons 106 of cylinders 107 connected to the supply line 80 via hand controlled valves 112. System for counterbalancing the web tension reaction caused by driving of the rewind shafts. The web tension reaction caused by driving of the front rewind shaft is equal to the moment of the web reaction P along a line which is a tangent to the front rewind roll at its point of contact with the contact drum 29 about the pivot 117 (Fig. 11) of the shaft 21 supporting arms. This moment is PW where W is the perpendicular distance from the tangent line referred to, to the pivot 117. The moment PW tends to force the rewind roll against the drum 29. The moment TB, where T represents the belt tension acting in the direction of the common tangent to the drive pulley of the rewind shaft and the main drive pulley 116 and B represents the perpendicular distance from that tangent line to the pivot 117, tends to force the rewind roll away from the drum 29. In order to counterbalance the moment PW due to web tension reaction therefore, the relative position of the pivot 117 and the centre 118 of the main drive pulley 116 are so chosen that over the range of rewind roll diameters the moment PW is substantially counterbalanced by the moment TB. If R=rewind roll diameter and d=diameter of the rewind shaft pulley then PR = Td or P = Td 2 2 R so that the condition required, i.e. PW= TB is satisfied when B is balanced by dW R dW The equation B= - may be satisfied with- R in the limits of variation of R (e.g. 3¢"- 20") by a proper selection of the distance between the arm pivot 117 and the axis 118 of the pulley 116 and the angle between the line 23a and a line from the pivot 117 to the axis 118 at a given rewind roll diameter, e.g. R=3¢". An analogous offsetting of the drive pulley pivot for the rear rewind shaft and the pivot of the rear rewind shaft supporting arms may be selected. U.S.A. Specification 2,650,039 is referred to.