Erdem Özdemir - 030070307 - 10th Week Definitions

Emery

 Manufacturing

In the ordinary process, the lumps of emery ore arc broken up in the same mantel as stone is for repairing macadamized roads, and into lumps of similar size. These lumps then crushed under stampers, such as are used for pounding metallic ores, driven by water or by steam power. It is supposed that the stampers leave the frag­ments more angular than they would be if they were ground under runners, a mode which is sometimes employed. The coarse powder is then sifted through sieves of wire cloth, which are generally cylindrical, like the bolting cylinders of corn-mills hut the sieves are covered with wire cloth, which vary from ninety to sixteen wires to the inch. No. 16 sieve gives emery of about the size of mustard-seed ; and coarser fragments, extending nearly to the size of pepper-corns, are also occasionally prepared for the use of engineers. The sieves have sometimes as many as 120 wires in the inch ; but the very fine sizes of emery are most commonly sifted through lawn sieves. The finest emery that is obtained from the manufacturers is that which floats in the atmosphere of the stamping-room, and is deposited on the beams and shelves, from which it is occasionally collected. The manufacturers rarely or never wash the emery ; this is mostly done by the glass-workers, and such others as require a greater degree of precision than can be obtained by sifting.

The following table shows the number of wires usually contained in the sieves, and the names of the kinds respectively produced by them:

Washing emery by hand is far too tedious for those who require very large quanti­ties of emery, such as the manufacturers of plate glass and some others, who generally adopt the following method:—Twelve or more cylinders of sheet copper, of the common height of about two feet, and varying from about three, five, eight, to thirty or forty inches in diameter, are placed exactly level, and communicating at their upper edges, each to the next, by small troughs or channels; the largest vessel has also a waste-pipe near the top. At the commencement of the process, the cylinders are all filled to the brim with clean water; the pulverized emery is then churned up with abundance of water in another vessel, and allowed to run into the smallest or the three-inch cylinder, through a tube opposite the gutter leading to the second cylinder. The water during its short passage across the three-inch cylinder, deposits in that vessel such of the coarsest emery as will not bear suspension for that limited time ; the particles next finer are deposited in the five-inch cylinder, during the somewhat longer time the mixed stream takes in passing the brim of that vessel; and so on. Eventually the water forms a very languid eddy in the largest cylinder, and deposits therein the very fine particles that have remained in suspension until this period; and the water, lastly, escapes by the waste-pipe nearly or entirely free from emery. In this simple arrangement, time is also the measure of the particles respectively deposited in the manufacture to which the emery is applied. When the vessels are to a certain degree filled with emery, the process is stopped, the vessels are emptied, the emery is care­fully dried and laid by, and the process is recommenced.

Holtzapffel informs us that he has been in the habit, for many years, of employing emery of twelve degrees of fineness, prepared by himself by washing over.

For optical purposes, Mr. Ross mixes four pounds of the flour of emery of com­merce, with one ounce of powdered gum-Arabic, and then throws the powder into two gallons of clear water; and he collects the deposit at the end of 10" and 30", and 2' 10/ 2Cr* and GO⁷, and that which is not deposited by one hour's subsidence is thrown away as useless for grinding lenses.

L;; .ii v paper is prepared by brushing the paper over with thin glue, and dusting the emery-powder over it from a sieve. There are about six degrees of coarseness. Sieves with thirty and ninety meshes per linear inch, are in general the coarsest and finest sizes employed. When used by artisans, the emery-paper is commonly wrapped round a file or a slip of wood, and applied just like a file, with or without oil, accord­ing to circumstances. The emery-paper cuts more smoothly with oil, but leaves the work dull.

(Ures̓ dictionary of arts, manufactures and mines, 1867, Andrew Ure, P201)






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Single-Spindle Automatic Lathes

Machining

The illustration shows a sin­gle-spindle, automatic, screw ma­chine designed for bar work of small diameter and arranged so that it is completely automatic in operation. 60-3(A). Bar stock of various shapes is fed auto­matically through a hollow spin­dle against a bar stop and held during the operation by a collet. 60-3(B).The tools are mounted around a six-station turret which is in a vertical plane. The ma­chine has a cross-slide which can carry tools on both front and rear. The turret indexes around a horizontal axis and is moved forward and backward on a slide which is controlled by a disc cam located at the right-hand end of the machine. 60-3(C). The cross-slide is controlled by two disc cams driven by the front drive shaft.

The front, rear, and right end of the machine are equipped with feed shafts for dog carriers, clutches, and cams that control operation.

Cams, clutches, levers, stops, and trip dogs are used to actuate and control the cutting tools without the attention of the op­erator. The stock is automatically fed and advanced the correct amount until the stock is used up. The control of the turret ro­tation, reverse spindle rotation to withdraw threading tools, and other operations are all done by self-acting mechanisms.

The camshaft usually rotates at a fixed rate of speed through­out the cycle. The cams that con­trol the various motions are designed so that each motion starts and stops at a suitable time.

End-working tools are mounted on the turret which feeds toward the headstock.

All the common machining operations, such as drilling, reaming, turning, boring, and threading, can be done on these machines.

Many types of accessories can be used.

(21st Centuty Manufacturing, 1994, DIANE Publishing Company, P280)

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