US258301A - Manufacture of files - Google Patents

Description

g Unites ST TES PATENT omea MARTIN A. HOWELL, JR, OF CHICAGO, ILLINOIS.

MANUFACTURE OF FILES.

SPECIFICATION forming part of Letters Patent No. 258,301, dated May 23, 188 2, Application filed July 5,1881. (No specimens.)

To all whom it may concern: 7

Be itknown that I, MARTIN A. HOWELL, Jr., a citizen of the United States, residing at Ohiago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in the Manufacture of Files and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to Which it appertains to make and use the same.

Heretofore files have been made from barsteel from steel cast in crucibles and forged into bars, in order to give greater tenacity to the metal, and to give a greater regularity to the combined carbon in the metal; but, in consequence of the repeated forgings,-l1eatin g, and reheating, much of the carbon is lost by the process, and the surface which should contain the carbon intact, in order to give the greatest hardness to the teeth, is rendered really the weakest, while the excess of labor attendant upon this process of forging of the blanks, and the waste of material and of f ucl enhance the value to the consumer.

The nature of my invention relates to the employment or use of decarburized cast-iron blanks in the manufacture of files, in cutting and finishing the same while the metal is in the soft decarburized condition, and in recarburizing the blanks after surfacing and cutting, in order that no carbon shall be lost by the pro cess, but retained intact where its presence is most essential for the purposes intended. By this means the original natural or granular character of the metal is preserved, the particles are not crushed by anyprocess of forging, the affinity for carbon is greater when heated to the proper degree, and a hardness is secured which can only be given by carbon unimpaired, thus enabling me not only to produce a much cheaper file, but one of far greater durability and regularity.

I take a medium grade of white or refined iron, charcoal-iron being preferred, more particularly Lake Superior iron. I proceed to produce my castings in the usual way from patterns in sand or flasks of refractory materials. When the castings are completed they are cleaned from anyadhering sand or dirt in a rattle-barrel, when the blanks are placed in flasks or saggers, interlaid with oxides of iron, iron scale, or any material having an affinity for carbon, kept at a red heat until the blanks are properly annealed, when, after gradual cooling, they are taken out, cleaned, and surfaced upon a grindstone, in order to prepare them fortheprocess of cutting the teeth, which is done in the usual way. The blanks are then placed in air-tight boxes, or boxes which can be kept air-tight by proper luting, interlaid with sifted carbon, animal or vegetable, or in a mixture of carbon and salts, all of which is well known, and varied to suit the taste ofthe operator or the character of the work intended to be produced, when they are kept at a red heat for a time corresponding to the depth of the carbon required,or the depth of the decarburized surface of the soft blank previous to cutting, when they are immediately taken from the cascs'and hardened in cold water, or cold water containing one of the forms of soda, in order to hold the contact of the water to the surface of the red-hot blank while immersed.

An uncertain degree of superficial hardness can be secured, without the use of the cementation process of embedding the blanks in carbon in cases, by heating the blanks to a red heat and coating the surface with the ferrocyanide or prussiate of potash, salts of ammonia, &c., and plunging the file'in water or other-liquids, all of which is well known; but I prefer the cementation process, as it gives a solid character to the work, and a durability absolutely requisite in the abrasion of hard metals.

It will be readily seen by any person versed in manufacture that the greater expense of refined bar-steel as compared with the castiron, the saving of fuel, ofwaste, and. largely of labor enables me to produce my blanks at a far cheaper rate than where produced by the wellknown processes in use, while the superi ority of the work in tenacity and durability is overwhelmingly in favor of this process.

I am aware that files have been made of wrought or bar iron by the same process as in common use in the making of steel files, save that they were hardened in a way somewhat analogous to mine, but of a veryinferior char-v acter, being equally expensive as to fuel, labor, and material, save a trifling difference in the latter, but rendered generally unsalable from the inferior and uncertain character of the hardness, and the liability of all such closelyforged metals to blister when subjected to the cementationprocess-a difliculty not encounwhich combines the decarburization of east- 15 iron blanks for the purpose of softening and cutting, with the subsequent recarburization for the purpose of hardening and tempering, substantially as set forth.

2. In themanufacture of files, the combined process of surfacing, cutting, recarburizing, and hardening ofdecarburized cast-iron blanks, substantially as and for the purposes set forth.

MARTIN A. HOWELL, JR,

Witnesses W. D. BRADSHAW, QHAs. E. SMITH.