(124) The construction of machines with flexible bends, in spite of many objections which are continually being alleged, continues to be large. It is held by some spinners and machinists that the necessity for adjusting the flexible bend manually from three points is faulty, and that it is better to provide mechanism whereby the setting can be made by positive means and from one point. Several patented arrangements with this view have been made, and illustrations of most of them are given. In most cases a flexible bend—somewhat differently constructed—is used, although it does not always have that name given to it.
Figs. 55 and 56.J.N.
(125) In Figs. [58] and [59] the arrangement used by Messrs. Dobson and Barlow—to which the name “Simplex” is given—is illustrated. Fig. [59] is a side elevation of that portion of the machine where the bend is applied. Fixed to the framing Q of the machine are four brackets P, O, M, L, the last three of which are specially curved on their upper edge, while P is shaped to a curve on its inner surface. Fixed in the metal strip K—which is practically the flexible bend—are four pins, each bearing an anti-friction runner, which are kept in contact with the edges of O, M, and L, and with the inner surface of the bracket P respectively. Attached to K, at the opposite end to P, is the crank S, oscillating freely upon a pin fastened in the frame Q. At the end of the bend K, where it is controlled by the bracket P, and, on its inner edge, a toothed rack is formed, with which a small spur pinion engages. The pinion is fixed on the axis of a worm wheel R, rotating on a pin fastened in the framing Q. With the wheel a worm R1 gears, and this can be rotated by a handle to any desired extent. When the bend K is moved by means of the rack in the direction of the arrow, it is put into tension, and the anti-friction bowls are drawn down on to the surfaces of the various branches. A glance at the detached sectional view given will show that the various brackets overlap the bend K, which slides between them and the frame Q. The position of the bend is arranged so that between it and the edge of the cylinder there is no open space left.
(126) Having thus described the actual mechanism a few words can be said about Fig. [58], which is a diagrammatic representation of it. The circle A B is that formed by the edge of the bend or plate K when it is at its highest position—that is, when the wire is unworn. The circle D E is that described by the edge of K when it has been drawn down to allow the flats to come nearer the cylinder. The small black dots represent the pins fixed in the bend K. When the latter is moved by the action of the rack and pinion, the end of the crank S follows the path of the circle described by it, moving from B to E during the time the entire depression of the plate is made. The anti-friction bowls in the same period travel in the paths shown, and it will be noticed that each of the curves is differently shaped. If the inner circle F G be supposed to represent that occupied by the edge of K after the crank end has travelled from B to G—a half circle—the curves L M O P would, if prolonged, be of the shape shown. Having obtained them in the manner thus described on paper, they are actually reproduced on the brackets by a milling machine fitted with a copying arrangement. By forming an indicator scale on the worm wheel R the amount of movement of the bend K can be regulated as desired to any degree of accuracy. The proportions of the worm, worm wheel, pinion, and rack, are so arranged that the advance of the wheel 1⁄50th inch will raise or lower the bend K 1⁄2000th inch. This method is very simple and effective.
Fig. 60.
Figs. 58 and 59.J.N.
(127) The arrangement adopted by Messrs. Howard and Bullough has the central idea of the employment of inclined surfaces, by withdrawing one of which the other can be lowered. It is shown in front elevation in Fig. [60] and in section in Fig. [61]. The fixed bend has formed on one side of it a broad flange, which is turned to a true circle on its upper edge. Upon this a segment of a ring A is placed, which can be slid in or out by means of the screw B and lock nuts. The back nut is riveted to the index disc E, which is divided into 36 spaces, the front lock nut securing the arrangement after setting. In front of the dial plate E an indicator finger D is fitted, which points out any alteration of the circular dial plate E. Upon the upper surface of the ring A a second ring C of a smaller section is placed. C is accurately turned on its inner side to correspond with the inclination of the upper surface of A, and on its outer edge is horizontal, so as to form a course for the end of the flat. The ring C is pressed down upon A by the weight of the chain of flats as they pass over it. The action of this mechanism is easily understood. By withdrawing the segmental ring A, by means of the screw B, the flats are lowered, the degree of their depression being sufficient to preserve the necessary distance between their wire teeth G and those F upon the cylinder H. The adjustment can be made in either direction, and the graduation of the dial E enables it to be finely made. In this case also, as shown in Fig. [55], the gap at the end of the cylinder is closed by bringing the flange of the fixed bend close to the edge of the cylinder.