(184) In Fig. [109] a side elevation of an arrangement made by Messrs. Platt Brothers and Company, Limited, is shown. In this case, also, the device of a sliding angular surface is employed. A slide H, which is guided in the upper part of the grinding bracket, and upon which a pull is constantly exercised by the balance weight M and chain shown, has affixed to its lower side the angular or inclined surface against which the flat end is pressed during grinding. As in the mechanism just described, the surface to receive the flat is formed with a lip, so that the forward traverse of the flats causes it and the slide H to move in the direction of the arrow. A slight curve corresponding to that of the bend is given to the sustaining surface of the slide, and the flat is thus held in a corresponding position to its working position. On the axle of the chain wheel by which the flat chain is driven is a toothed cam plate K, which is shaped as shown, so that it can give a forward movement to the lever L. The latter has fixed in it a tooth or catch, which constantly presses on the surface of the wheel K. The lever or bar L is formed with a slot at one end, with which a pin fixed in the end of the chain wheel axis engages, so that the lever can freely slide upon it. The other end of the lever is jointed to a lever B, fixed upon a short shaft on which is also fastened the short lever F and the curved arm D. There is a similar arrangement of mechanism at either side of the machine, and the two arms D are coupled by means of a round bar E, which acts as a weight. In this way a certain torsion is put upon the short shaft, and a tendency is set up in the lever F to move upwards. In doing so F presses against the slide G placed inside the framing and bend. The upper end of G when pushed up presses against the back of the flat and forces it against the inclined surface, where it remains until the flat is ground.
(185) The action of the mechanism is as follows: When a flat has passed under the grinding roller completely the rotation of the wheel K causes one of the teeth to push the lever L forward, and so oscillate the shaft upon which the lever B is fastened. This raises the arm D, and relieves the slide G of the pressure exerted by the weight E. The flat I at once falls out of contact with the surface of the slide H which is thus free to fall back into position to receive the next of the series, this being the position shown in Fig. [109]. It is essential to notice that, while the backward movement of the slide H is taking place it is out of contact with the flat, so that, neither during its forward or backward traverse is there any extra tension put on the chain. Immediately the slide has completed its movement the engagement of the catch in L with the tooth in K ceases, and L is free to slide inwards, which it is caused to do by means of the weight E. At the same time the slide G is pushed upwards, and lifts the next flat into contact with the inclined surface on H. It only requires to be said further that the pitch of the teeth on K ensures the requisite movements being given to G to cause the latter to engage every flat in its turn.
(186) The rollers and clearers are ground after removal from their places in the machine. A machine of which Fig. [110] is a perspective view is employed for this purpose, this being the type made by Messrs. Dronsfield Brothers, who have specially devoted themselves to this class of machines. The machine consists of a frame which has bearings formed, in which the shaft of the grinding roller revolves. Affixed to the lower portion of the frame is a counter shaft from pulleys, on which the emery roller is driven at a speed of 300 revolutions per minute. The roller to be ground is borne by the two bearings shown, which are slid laterally by the extremities of arms secured to a transverse spindle sustained by brackets fixed to the framing. The two arms are moved to or from the frame by means of a hand wheel which is keyed on a short spindle, on which is also fixed a worm. This engages with a quadrant fastened on the transverse spindle, so that the rotation of the worm in either direction gives a movement to or from the grinding roller. In this way the card roller is brought into contact with the grinding roller equally over its whole surface, the axis of the bearings in the arms being always parallel with those of the grinding roller. A bonnet is placed above the machine, and the dust is removed by the small centrifugal fan shown. The card roller is driven by a separate strap from the counter shaft.
(187) The flats of self-stripping machines are removed from the latter, and are secured on suitable bearings formed on the frames of a special grinding machine. The bearings are adjustable, so that the correct position is given to the flat during grinding. The faces of the flats when so held are moved across the grinding roller, which revolves at a high speed. As the arrangement is a very simple one, and does not present any great novelty, it is not necessary to describe it in great detail.
Fig. 110.
(188) As the wire clothing on the cylinder, doffer, rollers, and flats becomes filled with motes, neps, and short fibres, it is necessary to remove these periodically. This operation is called “stripping,” and it is a very important one. Whatever may be said to the contrary, stripping cannot be dispensed with unless some specific be found for the removal of the impurities as fast as they are taken out of the cotton. The plan formerly adopted for this purpose has fallen into disuse, as it implied the stripping of the card during work, and led to the mixing of the stripping with the finished sliver. It has been shown that a clean wire surface is the best for carding, and it will be easily seen that the filling of the spaces between the teeth will materially reduce the elasticity of the wires. Regular stripping is for this reason advisable; but the ease with which, if so carried out, the dirt can be removed, constitutes a further reason for this procedure. Carding speedily becomes poor in quality unless this is looked to, and all spinners should carefully watch this point. Another matter is, that inasmuch as it is practically impossible to strip all the cards simultaneously, the operation should be effected so that there should be an equal proportion of clean and dirty or half dirty machines. These are all little points, but they are of great importance in the effective working of a machine.
Fig. 111.
(189) The stripping of cylinders and doffers was usually carried out by a wire hand brush, the teeth of which are thrust into the wire spaces and then drawn downwards, so removing the “strips.” This is now entirely superseded by the revolving wire brush, such as is shown in Fig. [111], as made by Messrs. John Whiteley and Sons. This is a roller on which is wound card clothing made of hardened and tempered wire. It can be revolved by hand or power, and is carried in the grinding brackets. In stripping it should be set so that the teeth finally penetrate about 1⁄16th inch into those on the cylinder, but should be gradually set in to that depth so as to avoid damaging the wire. A speed of 200 revolutions for hardened and tempered, and 150 for mild steel cards is recommended by the makers, the cylinder revolving slowly in the meanwhile. The fleece of strippings thus produced is removed from the roller by dividing it along the narrow uncovered space shown, after which it will lift off by slowly revolving the roller. A similar plan is followed with the doffer. The rollers and clearers are usually stripped by hand, and it is hardly possible to adopt a better plan.