Patent GB-1229270-A (GB)
IPC: B65B13/22
Filed: 1968-12-12
Abstract: 1,229,270. Packaging. SIGNODE CORP. 12 Dec., 1968 [22 Jan., 1968], No. 59167/68. Heading B8C. [Also in Division F2] Strap handling apparatus comprises a strap tensioning means of a kind which tends to curl the strap by an amount dependent upon the degree of tension applied to the strap and strap straightening means arranged to apply to a surface of the strap in a manner to tend to reduce the curl, a pressure dependent upon the degree of tension applied to the strap. In the construction shown the strap tensioning means is part of a feeding and tensioning mechanism 15 which is mounted adjacent to a support 12 in which an article to be strapped is supported; as shown the article is a coil 11 of metal strip. The mechanism 15 feeds the strap 14, which is made of metal, from a reel into a shoot 13 which extends through the centre opening of the coil 11. The strap then passes into overlapping relationship to form a loose loop around the material of the coil, the tensioning means comprises a traction wheel 16 the periphery of which is provided with a plurality of teeth to engage the strap and a back-up wheel 17; the two wheels engage in opposite sides of the strap 14; the back-up wheel has a circumferential groove which provides the strap with a reinforcing rib 12. The traction wheel is mounted on a shaft 22 which is driven by a reversible motor 25 carried by a motor mount 26 the motor mount being journalled in bearings 27 for rotational movement about an axis 28 parallel to the axis 24 of the shaft 22. The back-up wheel 17 is mounted on a shaft 29 and the axis of the shaft is fixed. Clockwise rotational movement of the motor mount moves the traction wheel towards the back-up wheel and reverse movement of the motor mount moves it away. A spring 33 urges the mount 26 clockwise about its axis 28 and thus urges the traction wheel towards the back-up wheel to facilitate gripping the strap during the feeding operation. The mount 26 can be moved clockwise against the axis of the spring 33 by handle 34. Counter clockwise rotation of the shaft 23 causes the strap to be looped loosely about the coil 11 and the free end portion of the strap is then held against movement by any suitable gripping mechanism (not shown) and the motor 25 is reversed to retract the last said portion of the strap and to tension the strap around the coil 11. The forward feeding of the strap by the traction wheel causes its teeth to bite into the strap on one side and this tends to curl the strap; during the reverse rotation of the traction wheel as it retracts the last said portion of the strap to tension it around the coil 11 as the resistance to the tension increases the reaction rotates the motor mount 26 clockwise about its axis and this moves the traction wheel closer to the back-up wheel to increase the traction force against the strap and the teeth are caused to bite more deeply into the strap which increases the curvature of the strap; this is counteracted by the strap straightening means which is intially adjusted to exert just enough pressure against the concave side of the strap to deform it to the same extent but in the opposite direction to which it is curled when it is fed forwardly through the tensioning mechanism. The strap straightening means comprises a lever 35 pivoted on a shaft 36 intermediate its length. A pressure roller 37 is rotatably mounted near one end of the lever and a nose piece 38 also pivoted to the lever near the same end is urged clockwise by a spring 39 into contact with a base of the groove of the back-up wheel. When the motor mount is moved counter-clockwise to increase the tension in the strap the lever 35 is also moved counter-clockwise by mechanism described below, this movement of the lever 35 increases the pressure of the roller 37 proportionately to the increase in the curl of the strap so that the retracted portion of the strap is straightened. The mechanism which moves the lever to the motor mount to achieve this consists of a bar 47 which is rigidly secured to the motor mount at one end and to the other end of which a bar 46 is rigidly secured. The bar 46 has an aperture 45 through which a screw 43 extends and a cylindrical head 42 of the screw fits into a notch in the underside of the lever 35. A compression spring encircles the screw 43 above the bar 46 and urges the bar 46 towards the lever 35, one or more washers being interposed between the lever 35 and the bar 46 to vary the bias of the spring. Nuts are threaded on to the screw 43 to also enable the bias of the spring to be varied. When the motor mount moves counter-clockwise the bar 46 is moved in the same direction and via the spring the lever 35 is pivoted to force the roller 37 downwardly against the strap 14 to increase the pressure; with the proper adjustment of the spring by the washers and the nuts the increase in pressure against the strap 14 will deform the strap to counter act the increase in curl of the strap that is caused by the increase tension of the strap and will straighten the strap as it is retracted.