Fig. 87.
Fig. 88.
(169) Messrs. Platt Brothers and Company have recently devised a fastening of tinned wire, which is bent up by special machinery so as to form a continuous series of staples, the pitch of the points of which is about 1⁄2 inch. The staples are connected at the points, so that a length can be produced sufficient for fastening any flat. Holes are drilled in the flat through which the staples are pushed, and are pressed downwards and held. While in that position the points are clenched similarly to Messrs. Whiteley’s clip, and the clothing thus secured. This arrangement is practically a system of sewing without the disadvantage arising from the sawing of the edge of the flat. A strength equal to a riveted flat is obtained, with the advantage of a continuous grip along the flat strip. All these arrangements, however, imply the use of special machines to fix them, which is a condition not always attainable in a mill. For these reasons, where it is difficult to return the flats to a machinist for re-clothing, the use of rivets is most desirable.
(170) No less important than the proper fixing of the clothing in position is the operation of grinding it before starting work and after the points have worn. The licker-in is not ground, as the teeth do not require it, and their shape is such that grinding is impracticable. The cylinder is ground in position, and the question as to which is the correct method is one about which there is a good deal of controversy. In theory it is quite true that the periphery of a cylinder revolving, say, 180 times per minute, will tend to follow a path which is not an absolutely true circle. Further, the vibration set up in working, and the constant tendency from centrifugal action for the cylinder to roll forward, have a certain bearing on the subject. For these reasons there are some persons who contend that during the grinding of the cylinder teeth the cylinder should be run at its normal velocity, and the emery grinding roller be driven at a surface speed approximating to that of the cylinder. While this contention is theoretically correct, the disturbance caused by the high velocity of the cylinder is not of practical moment, and it is found to give the best results to run the cylinder slowly and the emery roller quickly. In all operations in which a true surface has to be established these conditions are found to be the best, and the grinding of a carding engine cylinder forms no exception to the rule. The danger of damage to the wire joints is much less likely, and the high speed of the grinder aids materially in light grinding, which it will be shown is of great moment. It is, therefore, the universal practice to reduce the normal speed of the cylinder to one varying from 7 to 11⁄2 revolutions per minute, and several special devices are in the market for the purpose. Before passing on to describe these, it may be said that the cylinder is ground by an emery roller, sustained in special brackets fitted to the machine framing, the position of which is shown in Fig. [44] at R. A similar method of procedure is adopted with the doffer, the brackets being placed at S.
(171) The most common appliance to obtain a slow motion of the cylinder is that known as Sykes’, which is shown in Fig. [89], as made by Messrs. Dronsfield Brothers, of Oldham. This consists of fast and loose pulleys, which are driven by a strap from a pulley on the line shaft. The pulleys are sustained in a frame which also carries a short strap, on which is fastened at one end a bevel and at the other end a worm. The frame is supported by the two legs shown, which can be adjusted to any length. The worm wheel is fixed on the cylinder shaft in place of the ordinary pulley, and is driven by the worm and gearing as described. A slow motion is thus given to the cylinder, and at the same time the grinding rollers are driven by bands or cords from grooves formed in a flange on the fast pulley.
Fig. 89.