Patent GB-425617-A (GB)
Title: Improvements in or relating to the control of feed reel brakes
IPC: B65H23/06
Filed: 1933-09-19
Abstract: 425,617. Feeding webs. HOLMES & CO., Ltd., J. H., North Drive, and KIMMIS, J., Rossie House, both in Hebburn-on-Tyne. Sept. 19, 1933, No. 25889. [Class 100 (i)] In a control arrangement for electricallyactuated feed-reel brakes, a winding of an electric motor, or of a solenoid or other electrical device controlling the brakes, is connected in series with a variable resistance regulated automatically in accordance with the feedreel diameter, to adjustable tapping-points on a potentiometer connected across supply mains, the arrangement being such that the percentage regulation of braking - force due to a change in the feed - reel diameter is approximately constant for the various settings of the potentiometer tapping-points. In the form shown in Fig. 1, the spindle A of a reel A<1> is provided with a brake drum B having internally expanding brake blocks B<1> connected by links to the plunger C<1> of a solenoid C mounted on a frame A<2> supporting the spindle A. The solenoid C has one end of its coil connected to one end of a potentiometer D connected across supply mains E, E<1>, and the other end is connected to the control member F<1> of a variable resistance F, the member F<1> being operated by a bell-crank lever G pivoted on the frame A<2> and carrying at its free end a roller G<1> which is maintained in contact with the periphery of the reel A<1> by a spring G<2>. The variable resistance F is adapted to be connected to the two contacts H<1>, H<2> of a relay H which is controlled by the stop button J of the textile or printing-press, to which the invention is applied, so that it is energized when this button is actuated to stop the press. The contact H<1> is normally closed so that the brake coil C is connected in series with the resistance F to an adjustable tapping- point D<1> of the potentiometer, while the contact H<2> is normally open but may be closed by the energizing of the relay to connect the brake coil to the adjustable point D<2> which is such that the maximum safe braking-force is applied to the reel. By means of a stop H<3> the contact H<2> closes before the contact H<1> opens. The initial braking-force is set by adjusting the point D<1>, and thereafter the braking-force is controlled automatically in accordance with the diameter of the reel A<1> by the introduction of more resistance by the member F<1>. The resistance of the potentiometer winding D is so chosen relatively to that of the solenoid coil C that the variations in the current passing through the coil C and resistance F do not appreciably affect the potential gradient across the winding D ; hence the percentage regulation of the braking- force by the introduction of the resistance F is substantially constant irrespective of the setting of the tapping-point D<1>. In the modification shown in Fig. 3, the magazine reel stand of a printing-press comprises a frame K having a main shaft K<1> carrying a spider K<2> which supports three paper reels. The shaft K<1> can be rotated by a motor O<2> through gears O, O<1>. The paper from the operative reel L is fed to the press over a roller K<6>, and when this reel is empty the next reel is brought into operative position in the usual way while the press is running at a slow speed. In order to facilitate the pasting operation a tension apron or, as shown, bands P are arranged in contact with the reel to act partly as a brake, but primarily as a backing against which the incoming reel presses the web from the expiring reel during pasting. Three bands P are anchored at P<1> to the frame K and are attached at their upper ends to a spring roller R mounted on the frame, the roller comprising an outer cylindrical member capable of rotating relatively to a spindle R<1> which it surrounds but to which it is connected by means of a spring R<2>. The spindle R<1> is provided at one end with a hand-controlled worm drive R<3> which prevents free rotation of the spindle but enables it to be rotated by hand to wind up or unwind the spring to adjust the tension of the bands P. As the diameter of the reel decreases the roller R rotates to maintain the tension of the bands P substantially constant. The angular movement of the roller R is thus proportional to the decrease in diameter of the reel. The arm or pointer of a variable resistance is connected to a spindle F<3> which is rotated by the roller R by a chain drive F<4>. The three feed-reels are each provided with brake drums having internally expanding brakes actuated by solenoids mounted on the arms of the spider K<2>. The connections from the solenoids are brought through a central hole in the shaft K<1> to slip rings so arranged that the coil of the reel in the operative position is connected automatically in series with the variable resistance, mounted in a casing F<2> to a potentiometer arrangement similar to that described above. Thus the angular movement of the roller R due to the decrease in the diameter of the operative reel varies the resistance to effect the automatic control of the braking current. Instead of actuating the brakes by solenoids, they may be actuated by means of an electric motor connected thereto by gearing, and which exerts a braking- force depending upon the relation between the currents flowing in its armature and field winding. One of these windings can be energized from a source of constant E.M.F., and the other winding can be connected in circuit in the same way as the coil of the solenoid as described above. Also magnetic brakes can be used of the kind in which the brake coil is wound on a core having an armature consisting of a disc or drum of magnetic material carried on the reel spindle so that when the coil is energized the braking-action is due to the magnetic attraction between the core and the rotating armature on the spindle.