US3255289A - Methods of making abrasive wheels - Google Patents

Description

J. L. HENSLEY June 7, 1966 Filed Dec.

June 7, 1966 J. 1 HENsLEY 3,255,289

METHODS OF MAKING ABRASIVE WHEELS Filed Dec. 6, 1961 2 Sheets-Sheet 2 Fig, 6 INVENTOK JAMES L. HENSLEY BY MAM,

ATTORNEYS United States Patent O 3,255,239 METHODS F MAKING ABRASIVE WHEELS James L. Hensley, Knoxville, Teun., assignor, by mesne assignments, to Tysaman Machine Company, Inc., Knoxville, Tenn., a corporation of Delaware Filed Dec. 6, 1961, Ser. No. 157,514 4 Claims. (Cl. 264-316) This invention relates to improvements in methods of making abrasive wheels, particularly of the character used for cut-oit machines.

One method of manufacturing abrasive wheels involves the use of a circular type press. The desired quantity of abrasive material is forced into the mold and spread over the area thereof. This material usually is made of abrasive particles combined with a binder capable of being pressed and hardened to form a disc. a disc may be made up to thirty-four inches in diameter and seven thirty-seconds inch thick. A top mating pressure plate is used to press the material to the desired shape and density.

Thereafter, the wheel thus formed is removed from the press for curing. It must be kept flat until fully cured and ready for use. If laid without support over the entire area thereof, the wheel is subject -to warping,taking a permanent set out of atness, which would destroy its usefulness.

In the use of an labrasive wheel, especially of large diameterl size, and in making deep cuts, the wheel is subject to many adverse operating stresses, such as excessive side binding which required increased power to continue the operation thereof. Moreover, cooling of the wheel becomes difficult in making deep cuts.

It has long :been known that the wheel would be improved by making the rim section thicker than the web section inwardly of the rim, but no satisfactory Way has been found lheretofore of-making the wheel with a thicker rim and maintaining it in condition for use. An attempt has ibeen made to shape the press to form a uniform taper in the web section continuously from the peripheral edge of the rim to the center. This left a feather edge that was not sulicient to prevent side travel. Moreover, it required a pallet having a supporting surface complementary to the surface of the wheel to support the latter to prevent distortion to one lllat side during curing and continuously until put into substantial use.

One object of this invention is to overcome the objec- -tions to abrasive wheels with straight sides and -to improve the method of making abrasive wheels.

Another object of the invention is to provide in the method of manufacturing an abrasive Wheel with a thickened rim, of support means therefor within the face of the wheel and readily removable when the wheel is ready to be put t'o use..

Still :another object of the invention is to provide for molding an abrasive wheel upon a separate core placed within the mold and of .appreciably smaller area than the area of the mold and wheel and molded in the surface of the wheel to rbe removed from the mold therewith but capable of ready separation from the wheel when the latter is to 4be used.

These objects may be accomplished by placing one or more sheets of material in the bottom of the mold and of appreciably less area than the area of the mold, and also of appreciable composite thickness so as to form a web section of less thickness than the thickness of the rim section. The material used in the mold can be of varying or Vany desired thickness according to the amount of stepped Frequently, such ice taper desired in the finished Wheel. A like number of shee-ts of material preferably are used under -the pressure plate on top of the composition for a properly balanced wheel. 'These sheets would adhere to the formed wheel and remain thereon after removal from the mold and duringA curing, and, in fact, until the wheel is ready for use.

This method is illustrated in the accompanying drawv ings, in which: I

. FIG. l is a cross section through a mold showing layers of molding material to be .applied to opposite sides of an abrasive wheel in the molding thereof; A

FIG. 2 is a cross section through the molded wheel after removal from the mold;

FIG. 3 is a similar View of the wheel ready for use;

FIG. 4 is .a cross section of the wheel in the work;

FIG. 5 is a plan View of a modied form of wheel;

FIG. 6 is a detail perspective view of 4the modified abrasive lwheel made with molding -sheets of material of the character illustrated in FIG. 5; and

FIG. 7 is a sectional view of the modilied abrasive wheel in the work.

The relative sizes and dimensions of parts are exaggerated in the drawings for clearness of illustration.

'The invention is illustrated in connection with a mold of conventional form for clarity of illustration. This mold comprises top ,and bottom platens 1 and 2 shaped to mold a mass of abrasive plastic material to form a wheel of the desired contour and size.

The bottom platen 2 isA provided with a cylindrical cavity 3 having a bottom face 4 usually smooth and flat.

The under surface l5 of the top platen 1 is also usually flat and smooth continuously throughout the area of the -top platen 1.

The means for forming the center hole in the wheel is illustrated as a pin 6 rising from the lbottom cavity face 4 and of la length to extend entirely through the mold cavity. Any suitable means may be used for the purpose.

In making a wheel according to this invention, the moldable abrasive material is placed in the mold cavity 3 of a quantity according to Ithe size and thickness of the wheel to be made, after which the t-op platen 1 may be applied thereto to effect the molding'operation in the usual way. Suitable pressure is applied to the top platen and held for a length of time suiiicient to effect the molding operation. Lining sheets a and b are shown in FIG. 1 extending over and throughout the respective areas of the surfaces 4 and 5 t-o facilitate separation of the molded wheel therefrom. These lining sheets may be used if desired, but are not required according to this invention.

The abrasive wheel is illustrated in FIGS. 2 to 4, made with a thick'rim section R and a lrelatively thinnerl web section W. This relatively thinner web section W is formed by one or more'molding sheets on either or both sides of the mold cavity. In the example illustrated., such molding sheets are shown at c, d and e stacked flatwise on the bottom face 4 of the cavity 3, and also three such molding sheets are shown at f, g and h stacked against the bottom face 5 of the top platen or the lining sheet b, if used.

Each of the molding sheets c to h extends symmetrically of the mold cavity but has its periphery spaced inwardly an appreciable distance from the periphery of the cavity. The largest diameter sheet or sheets thereof are at the inner periphery of the rim R. Y Where several sheets are used in each stack these form shoulders S on the face or faces of the wheel in one or more steps between the rim R and the web W of the wheel. v

The molding sheets c-h may 4be held in placein any suitable manner in the mold cavity and on the undersurface of the top platen 1. The sheet or sheets in the bottom of the cavity may be provided with central openings to t around and on the central pin 6. In like rrianner, the sheet or sheets that are secured to the undersurface of the top platen l may be held in place around the opening in the bottom face of that platen in which the pin 6 is received when the platen is inserted in the cavity. Suitable means should be provided on the top platen to hold the sheets thereto, but to allow ready separation therefrom when the top platen is removed from the mold.

The molding sheets c-z may be formed of any suitable material found desirable for the purpose, such, for example, as kraft paper, wax paper, or aluminum foil. The material should .be such as would enable the sheet or sheets to be peeled readily from the formed abrasive disc or wheel when the latter is to be put into service. The molding sheet, if one is used on each surface, or the composite sheets if more than one are used on each surface, should 'be of suflicient thickness so as to separate the web section W from the rim section R and to provide a delinitely thicker -rim section than the we-b section, as somewhat exaggerated in FIGS. 3 and 4. The greater thickness, nevertheless, of the rim section should be such as will provide a radial addition to the rim of uniform thickness so as to provide denite support for the Wheel in the kerf formed in the material to prevent side travel of the wheel in operation. At the same time, the spacing of the web portion from the sides of the `formed kerf permits free access of the cooling liquid to the rim and substantially throughout the area of the wheel to obtain maxi mum cooling effect.

After molding the wheel with the .molding sheets embedded therein, the wheel is removed from thev mold and cured in the usual manner. The molding sheets remain in place on the wheel until the latter is -ready for use. Then they may be peeled off or separated, so as to provide for the operation of the wheel in the usual manner. When in place on the wheel, the molding sheets provide uniform support for the wheel, both during curing and during handling or storage.

Usually, these molded abrasive wheels are supported flat and they require support continuously throughout the area of each to prevent the possibility of distortional warpage. By molding the sheets directly in the surface of each wheel, the sheets 4remain in the wheel embedded -therein and support the surface uniformly throughout.

Moreover, the provision of molding sheets in the cen- -ter portion of the wheel, spaced inwardly from the surrounding rim section, provides for greater pressure being applied to this center section, which will compact the moldable abrasive material with greater density than in the lrim section. Thus, the wheel will harden more etectively in the center and produce a more durable wheel ythan one of uniform density throughout.

It is also possible to use molding sheets to modify the surface of the abrasive wheel in other respects than has 'been illustrated in FIGS. l to 4. One such sheet would 'be used in the `bottom of the cavity and another preferably in the top thereof under the top platen. When the abrasive material is thus deposited in the cavity between the sheets, a wheel would be molded in the usual manner, as indicated at W in FIG. 6. Such `a wheel would have alternate lribs and grooves extending radially thereof on one or both opposite faces of the wheel, which would -liave excellent cutting and cooling effect and would minimize side binding during the operation of the wheel, as will be apparent from FIG. 7. The alternate g-rooves and ribs will provide courses W2 for the cooling liquid to flow radially outward along the wheel entirely to the periphery thereof from the center portion W3 thereof during the operation of the cutting of metal, stone or other materials. In other respects the method of use and of manufacture illustrated in FIGS. 5 to 7 would be the i same as set forth above and involve the use of similar materials.

While the invention has been illustrated and described in certain embodiments, it is recognized that variations and changes may 'be made therein without departing from the invention set forth in the claims.

I claim:

1. A method .of making an abrasive wheel having a thicker peripheral rim and a thinner central web comprising introducing a mass of moldable abrasive material into a circular cavity and extending continuously over the area thereof, applying molding sheets between opposite sides of the cavity and the moldable Imaterial and of an area covering the major portion of the area of the cavity but smaller than the area of the cavity, pressing and -molding the material in the cavity forming a continuous rim yaround the periphery of the sheets and a central web portion between the sheets, removing the formed wheel with the sheets thereon from the cavity, and thereafter peeling the sheets from the surfaces of the wheel.

2. A method of preparing .for use an abrasive wheel comprising applying Hat molding sheets to opposite faces of a circular molding cavity having appreciably greater diameter than the depth of tlie cavity to form opposite side faces of the wheel and of an area to cover the major portion of the side face area of the cavity but less than the entire area thereof, introducing into the cavity between the sheets a plastic molding .material having abrasive particles embedded therein and extending continuously as one mass over substantially the entire circular area of the cavity, pressing and molding the material in the cavity with the sheets embedded in said opposite faces and with a space between the periphery of the sheets and the periphery of the cavity forming a rini on the wheel, removing said formed wheel from the cavity with the sheets embedded in the surfaces thereof, and thereafter peeling the sheets from the surfaces of the Wheel.

Ei1 A method of preparing for use an abrasive Wheel having a surrounding rim and with a web portion of less thickness than the rim for the circulation of a cooling fluid 'by the web portion to the rim, said method comprising introducing into a circular mold cavity and spreading over the area thereof a uniform mass of moldable plastic material having abrasive particles embedded therein and with a plurality of thin molding sheets at opposite sides of said mass of material between the latter and the adjacent faces of the cavity at the center portion of the cavity, applying pressure to said material until the mate- -rial is set to form a wheel and with the material between the sheets forming the web portion, removing the formed wheel from the cavity with the sheets in place embedded therein to support the web portion when the wheel is laid on its side face until use, and said sheets being adapted to be removed from the side faces before use.

4. A method of making an abrasive wheel having a peripheral portion thicker than the center portion thereof, said method comprising applying a plurality of thin circular molding sheets in the bottom of a circular molding cavity coaxially thereof and of each other and with the sheets of progressively larger diameter from top to bottom of said plurality, spreading over the area of the cavity and over the plurality of sheets a uniform mass of plastic material having abrasive particles embedded therein, superposing over the mass of material a second plurality of thin circular molding sheets of progressively larger diameter from `bottom to top thereof, placing a compression member over the second plurality of sheets, applying pressure to the assemblage to cause the mass to ow and form a wheel in the cavity, and removing the formed Wheel from the cavity with both plurality of sheets in place during storage, and said sheets being adapted to be removed therefrom before use.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Arthur 51-209 Bell 264-259 Harvey 51-209 Goepfert et zal. 18-59 Belcher 51-206 ROBERT F.

Reidenbach 51-209 Von Doenhoff 51-206 Davis 264-259 Sucher 264-316 WHITE, Primary Examiner.

ALEXANDER H. BRODMERKEL, Examiner.

Claims (1)

1. A METHOD OF MAKING AN ABRASIVE WHEEL HAVING A THICKER PERIPHERAL RIM AND A THINNER CENTRAL WEB COMPRISING INTRODUCING A MASS OF MOLDABLE ABRASIVE MATERIAL INTO A CIRCULAR CAVITY AND EXTENDING CONTINUOUSLY OVER THE AREA THEREOF, APPLYING MOLDING SHEETS BETWEEN OPPOSITE SIDES OF THE CAVITY AND THE MOLDABLE MATERIAL AND OF AN AREA COVERING THE MAJOR PORTION OF THE AREA OF THE CAVITY BUT SMALLER THAN THE AREA OF THE CAVITY, PRESSING AND MOLDING THE MATERIAL IN THE CAVITY FORMING A CONTINUOUS RIM AROUND THE PERIPHERY OF THE SHEETS AND A CENTRAL WEB PORTION BETWEEN THE SHEETS, REMOVING THE FORMED WHEEL WITH THE SHEETS THEREON FROM THE CAVITY, AND THEREAFTER PEELING THE SHEETS FROM THE SURFACES OF THE WHEEL.

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