US1081082A - Method of grinding. - Google Patents

Description

-G. I. ALDEN.

METHOD OF GRINDING.

APPLICATION FILED FEB. 11. 1910.

Patented Dec. 9, 1913.

2 SHEETSSHEET 1.

Inventor /1/a'/ne,6,5e,s.. ,5 W Ecorgefilclem 6. 1729 By 170 toi'neys. m SM G. I. ALDEN.

METHOD OF GRINDING.

APPLICATION FILED r2341, 1910.

1,081,082. Patented Dec. 9, 1913.

2 SHEETS-SHEET 2.

7?,Z17 aM GeorgeI/flden.

UNITED STATES, PATENT OFFICE.

GEORGE I. ALDEN, 0F WORCESTER, MASSACHUSETTS,'ASSIGNOR TO NORTON GRINDING COMPANY, OEWOROESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

. METHOD OF GRINDING.

To all whom it may concern."

Be it known that I, Gnonon T. ALDEN, a citizen of the United States, residing at \l'orcester, in the couhty of Worcester and State of lvlassachusetts, have invented a new and useful Method of Grinding, of which the following is a specification.

This invention relates to a method of grinding thin knife blade and cutter blanks. Blanks of this kind have been ground ordinarily by hand on natural stones and any attempts that may have been made heretofore, so far as I am aware, to grind them automatically and particularly on artificial stones, have been commercially unsuccessful. This is due to the fact that these blanks easily become burned when ground in this way, and no efi'ective means was known for avoiding it.

This invention is designed for the purpose of overcoming these difficulties and providing a practical method and efficient means for accomplishing this result.

Reference is to be had to the accompanying drawings in which- Figure 1 is a front elevation of a pre ferred form of machine for carrying out this invention. Fig. 2 is a sectional view showing certain details thereof, and Fig. 3 is a plan showing a cutter in position for grinding and illustrating how the stream of water is applied thereto.

Several kinds of blades are manufactured from blanks which have square edges that must be ground off to an acute angle before they are put upon the market. This particularly 1s the case with mowing machine knives or cutters. So far as I am aware, such articles have ordinarily been ground in the shop practically by hand, that is, each blade is manipulated by a workman on the surface of a natural grinding stone. Obviously, much greater speed and economy in production could be obtained if these blades could be ground on artificial stones, as for example, emery or corundum wheels which have a much more rapid cutting action than the natural stones. Heretofore it has been regarded as commercially impracticableto grind thin blades, such as mowing-machine cuttersections, upon such artificial wheels, by reason of the liability of burning the blades or drawing their temper, even when the blades were completely flooded by water. The object of the present invention is to Specification of Letters Patent. Application filed February 11, 1910. Serial No. 543,298.

Patented Dec. 9, 1913.

provide an-apparatus and method whereby this difficulty may be overcome, so that an artificial grinding wheel, even of comparatively fine grain, may be used without danger of imury to the blanks. In order to accomplish this result I have discovered that it is not sufficient to cool the blades in any way heretofore known, as flooding the blades with cold water under ordinary conditions will not carry away enough heat, and even the entire submersion of the blades in cold water would not cool them with sufficient rapidity when operated upon at high speeds by artificial grinding wheels.

of suitable fineness. I have discovered however, that the heat can be carried away by introducing cold water on the blades while being ground under a high pressure and at a correspondingly high velocity and directing that water on the side of the blade opposite the wheel in a fine stream along a line slightly back from the extreme sharp edge being formed, and parallel thereto. I have found in practice that when operating upon ordinary mowing machine cutters, such as are now manufactured in large quantities in this country, if the steam is directed in the manner above described, a pressure of from 100 to 150 pounds per square inch is very suitable for the purpose. I believe that one reason for the decidedly different result obtained by the use of water under pressure in this way is due to the fact that when the water is applied to the blades in a comparatively quiescent state, the heat of the blank is sufficient to partially vaporize the water and cause minute bubbles or particles of vapor to adhere directly to the surface of the blade. The vapor as is well known is not as good a conductor of heat as the water itself, and consequently, it tends to hold the heat. By applying the water under sufiicient pres sure to cause it to flow with comparatively great rapidity, the vapor has no chance to form or if it does form it has no opportunity to cling to the surface of the blank, but is forced to more along the same. As soon as it is dislodged from its original place of formation, it will move out of close contact with the surface of the blade, so that the water can come into contact with the metal. As no particle of steam can remain for any appreciable length of time in any place, the water has a chance to get at every part of the surface of the blank. In this way, therefore, an eilicient cooling is secured, and-.it'has been amply demonstrated in practice that the thinjblanks can be ground 1nth1s'way on an emery or corundum wheel of come parative fineness at a yei'y high speed withou t danger of burning.

The invention is illustrated in a form in which a base 4 supports a tank 5 in which are mounted'emery or other artificial grinding wheels 6. The cutter blanks B are held on a table plate 7 in position for grinding by .plungers 8. The mechanism for operating the plungers does not constitute a part of this patent but toggle levers 9 are shown. Two wheels are shown so that the blanks can be moved along the table plate from one to the other and ground on both sides.

A pump 10 of any desired character is provided drawing water from any source, preferably from a settling tank 11 and supplying it' to a pressure tank 12 under considerable pressure. ample that a pressure of 100 to 150 pounds per square inch is very suitable for this purpose. From this tank the water is forced through a pipe 13 into a pair of distributing pipes 14 through a valve 15'. From each of the pipes 14 it passes by means of connections 16 into a chamber 18 in each of the plungers 8. The support for each plunger is provided with an elo ated passage 19 for receiving the connection 16 in all positions of the plunger. The bottom of the. plunger is provided with'a long narrow slot 20 by which the water issues 1n direct contact with the blank along a line a little back from the edge during the entire time during which the blank 1s being ground. In fact the cooling water under this heavy pressure is dischar ed on the blade throughout the time while it is in position so that in addition to cooling the blade it keeps the other parts of the mechanism cool.

I have found in practice that by providing a flow of water under high pressure the heat is carried ofl with such rapidity that even with thin blanks of the particular temper required for mowing machines no appreciable burning or temper drawing takes place. The water is discharged over the blades on the surface of the stones and issues from an opening'21 in the casin' 5. It then passes into the settllng tank w ere it is strained and settled so that the particles removed from the stones are left in the bot- I have found for ex-.

vention described nor ,to the exact use of the invention referred to but What I do claim is: 1. A method of grindin cutter blanks which consists in applying t em to a grinding wheel and forcin a coolingliquid under high pressure and ve ocity against the blank on the side opposite the wheel in a thin stream along a line parallel with and at a short distance from the extreme edge being ground.

2. A method of grindin cutter blanks which consists in applying t em to a grinding wheel and forcing a cooling liquid under high velocity against the blan along a line parallel with the extreme edge being ground.

3. A method of grinding mowing machine knife-section blanks, which consists in applying first one ed e and then the other to a air of grin ing wheels, and

while the e ges are in contact with the wheels applying a thin stream of water under pressure near said edges.

4. A method of grinding blanks, which consists in applying the cutting edge thereof to the surface of a quick cuttin grinding wheel, holding the blank in su stantially stationary position until ground, and constantly forcing cooling fluid under pressure of more than one hundred pounds per square inch against the blank in a'thin stream parallel wit-h, and uniformly throughout the extent of, the cutting edge and at a slight distance therefrom,- in position to run the cutting edge on the wheel.

In testimony whereof I have hereunto set my hand, in the presence of two subscribing witnesses.

GEORGE I. ALDEN.

Witnesses C. 0. SMITH, A. J. DUPRli.

over

Images