US1820581A - Abrasive wheel - Google Patents

Description

Aug. 25, 1931. A. RICHMOND ET AL 1,820,581 l ABRAS IVE WHEEL Filed March 30, 1928 @S51-@Rm v Afro/MEM grinding wheel.

-Patented Aug. 25, 1931 UNITED STATES Lazise PATENT OFFICE HAROLD A. RICHMOND AND DAVID D. MACLAUGHLIN, 0F NIAGARA FALLS, NEW YORK, .ASSIGNORS TO GENERAL ABRASIVE COMPANY, INC., 0F NIAGARA FALLS, NEW

YORK, A CORPORATION or NEW YORK ABRASIVE WHEEL Application filed March 30, 1928. Serial No. 265,900.

Our invention relates to the class of abrasive wheels known as cylinder, ring and cup wheels, of integral construction, as distinguished from such wheels of segmental contruction.

In operating a cylinder, ring or cup wheel, the wheel is held at one end in a chuck or holder, and revolved in either a horizontal or vertical plane. By means of roper feeding mechanism the other end o is brought in contact with the Work, which may have a rectilinear or circular motion or it may be held in a fixed position While the grinding wheel moves across it. Cylinder and cup wheels are used for. grinding flat surfaces. The grinding face of such wheels is also flat. Therefore the area of contact between the wheel and the work is large compared with that in grinding operations done with a disk wheel, where only a short arc of the' wheel comes in contact with the work, whether the latter is circular or flat or irregular, in contour.-

This large area of Contact between the wheel and the work makes diflicult the quick escape of the particles removed by grinding and the particles of abrasive worn ofi' the The wheel therefore, does not clear itself readily and the presence of these waste products between the wheel and the work impairs the cutting action 'of the wheelg If the wheel is used for grinding metal, as is usually the case, the metal grindings become imbedded in the face of the wheel, causing itv to glaze and so lose its free cutting qualities. Various devices have been used to improve the efficiency of cylinder and cup wheels'. Among these are the use of extremely soft, i. e. weakly bondedwheels, which however wear out rapidly; the use of thin walled cylinders to reduce the area of contact, but this' shortens the life of the wheel, reduces production, and impairs the finish; the introduction of water inside the wheel to help wash away the grindings;

\ making the wheels in segments with space between the segments; and molding axial recesses on the inner or outer surface of the abrasive cylinder. Segmental` wheels are structurally weak, they are difficult and slow the cylinder l to assemble, and uneven in grade owing to variation between the individual segments. If the segments are set deep enough in special chucks to hold them safely, a large percentage of the wheel is wasted; and wheels so held cannot be mounted in the holders now in common use on grinding machines. The segments cannot 'project far from the holder without danger of breaking in use; Mconsequently they wear out quickly and must be frequently replaced. Cylinder wheels with axial recesses lack strength, especially if the recesses are on the outside. If on the inside the recesses accumulate the Waste products since no free escape for these is provided. In either case complete clearance across the cutting face of the wheel is lacking.

We have found that a series of slots in spaced relation and extending thru the Walls of integral annular grinding wheels with masses of imperforate solid abrasive material between them, provide continuously, as the Wheel wears away, an eflicient means of escape for the waste products, without unduly weakening the wheel. Such wheels clear themselves effectively, filling or glazing is avoided, and the wheels preserve their original sharpness and efficiency throughout their life. Vheels of this description may be used interchangeably with ordinary annular grinding wheels in chucks or holders now in common use on grinding machines. Where wheels with axial recesses are used or wheels having axial lholes in the cutting face, it has been found that there is a strong tendency for the products of grinding to accumulate and pack in the recesses or holes. In our wheel these products escape readily thru the slots adjacent to the work. These slots are worn out. Due to the ample clearance vprovided in our wheel, harder, i. e. more strongly bonded, wheels may be used and longer life thereby obtained. For the same reason wider v faced, and therefore stronger, wheels may be used and since wider faced wheels contain more abrasive they will do more work and do it quicker. They will also give a better finish. If the slots, instead of being radial are made tangential to a circle, smaller than the 4internal circumference of the cylinder, a

f water or other liquid to dissipate in part the vheat which is generated in the operation of grinding and so prevent overheating and distorting the work. The liquid also acts as a lubricant to minimize the production of heat. To be effective the liquid must pass between the surface of the grinding wheel and the material which is being ground. There are practical difliculties in introducing the liquid in this place, since the grinding face of the wheel is constantly wearing away and the wheel holder, which must carry any device for supplying Water inside the Wheel, is constantly approaching closer to the Work. Therefore in grinding machines'now in use employing annular grinding wheels, the water is introduced a considerable distance above the grinding face. Since the wheel and its holder revolve at high speed the Water is quickly thrown radially outward against the inside of the cylinder or cup wheel. In an annular abrasive wheel having slots extending thru the walls, much of the liquid would escape thru the upper slots without serving any useful purpose. It would alsobe sprayed about the vicinity of the grinding wheel. To prevent this premature escape of the liquid we provide an interior coating of sulphur, beeswaX, or other suitable water proof material. This covers the entire inside surface of the annular grinding wheel, including the slots. Liquid introduced near the upper, or back, face of the wheel strikes this coating and travels downward over the coating until it reaches the plane of the grinding face, where it is carried under the face by centrifugal force and the revolution of the wheel, thereby performing its function of cooling the' work and lubricating the wheel.

In order to cut freely annular abrasive wheels have to be made in soft grades, that is grades in which the grains are weakly bonded. Such wheels are less able than wheels of medium or hard grades to resistl stresses developed in use by centrifugal force, vibration, grinding resistance, etc. To further strengthen our wheels We prefer to reinforce them by means of metal bands fitting closely about the outside surface. These bands are preferably made of wire Wound about the cylinder in sets of four to six strands, the strands being soldered together. The sets may be located about three quartersof an inch apart. NV hen the wheel is Worn away to the first set of wires, Athese are re moved; similarly the second and third are removed as required by the wearing away of the 'wheel in use.

Referring to the drawings:

Figure l is an elevational View with parts broken away of an abrasive wheel embodying features of the invention.

Fig. 2 is a horizontal sectional view illustrating a modification, and

Fig. 3 is a transverse sectional vieu7 illustrating another modification.

In the drawings 1 is a cylinder wheel having radial slots 2, the wheel is shown sulphured into a holder 3 of a type in common use. This holder has a water groove 4 to supply water thru the holes 5 to the inside of the annular grinding wheel. 6 is a waterproof coating covering the inner wall of the cylinders. The cylinder is shown partly worn off', so that one row of slots 2 is Open at the bottom. 7 are sets 'of Wire bands.

As shownl in Fig. 2. the slots 8 are tangential to a circle smaller than the internal circumference of the cylinder.

In Fig. 3 the slots 9 are inclined to the flat faces of the cylinder.

In each case the slots are spaced around the wheel and the portions 10 of the wall between the slots are imperforate solid masses of abrasive material.

We do not limit ourselves to the shape, arrangement, or position of the slots shown in these specifications. The scope of our invention covers all abrasive cylinder or cup wheels having slots extending from the outer to the inner surface of the circular wall. These slots may be of more than one size or shape in the same wheel.

We claim:

1. An integral annular abrasive wheel having slots extending thru the wall, and a waterproof coating covering the inner ends of the slots. f

2. An integral annular abrasive Wheel having slots of different sizes, extending thru the wall, and a waterproof coating covering the inner ends of the slots.

3. An integral annular abrasive wheel having slts tangential to a circle smaller than the internal circumference of the wheel and extending thru the Wall, and a waterproof coating covering the inner ends of the slots.

4. An integral annular abrasive Wheel having slots of different shapes, extending thru the Wall, and a waterproof coating covering the inner ends of the slots.

5. An integral annularabrasive wheel having slots inclined to the flat\faces of the wheel and extending thru the wall, the inner ends of said slots being covered by a waterproof coat.

6. An integral annular abrasive wheel having slots extending thmthe Wall, said slots being so arranged that one side of some of the slots is always open as the wheel wears away, the inner ends of said slots being 'covered with a waterproof coatin HAROLD A. RI HMOND. DAVID D. MAcLAUGI-ILIN.

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