US2027132A - Grinding wheel - Google Patents

Description

Jan. 7. 1936. WEBSTER 2,027,132

GRINDING WHEEL Filed Dec 19, 1934 iiiii I I i ii'i riiiiiiiik i IX I\\ 1 \N WITNESaEs DUANE E. WEBSTER cutting operation.

Patented Jan. 7, 1936 PATENT OFFICE GRINDING WHEEL Duane E. Webster, Worcester, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application December 19, 1934, Serial No. 758,279 lo claims. (01. 51-206) This invention relates to a grinding wheel, and more particularly to a cutting-off wheel which is very thin in comparison to its diameter and adapted to be employed in the nature of 'a rotary saw for rapidly cutting deep narrow grooves or cutting off lengths of work.

Many of the present-day cutting operations which were formerly accomplished with rotary steel saws are now being done much more rapidly and efficiently with cutting-off grinding wheels. These cutting-oil wheels, which are 20 inches or less in diameter and /8 of an inch or less in thickness, are provided with substantially flat,- parallel, opposed side faces and they depend solely upon the sharp abrasive grains projecting from the wheel periphery to perform the These wheels are fragile bodies and in view of the fact that they are very thin as compared to their diameters, they cannot be subjected to any transverse pressures. It is common practice for these wheels to rotate as fast as 16,000 surface feet per minute. Hence,

wheel breakage during a cutting-off operation would not only seriously endanger the machine operator, but would probably cause spoilage of the work. i

Although these high speed cutting-01f wheels are capable of a very fast-cutting operation as compared with the familiar type of circular steel saws, the safe cutting rate is very much limited in comparison with the cutting ability of the wheel since insufficient opportunity is provided for dissipation of the excessive heat of grinding. Consequently, many of these wheels are used at too high a speed and fed too' rapidly into the work, with the frequent result that the heat of grinding softens the wheel bond causing uneven stresses within the grinding wheel and changing its abrading characteristics, thereby warping and often breaking the wheel and injuring the work as well as endangering the operator of the machine. Many of these thin cutting-off wheels tend to wear away most rapidly at their peripheral edges, causing them to gradually become narrower in thickness at their periphery than at their central portion. A grinding wheel worn in this manner rapidly becomes wedge shaped and does not cut sufilcient clearance for itself as it enters the work, with the consequent result that it tends to bind within thework and break.

Even if a wheel which becomes worn in this manner does not break, it produces an unsatisfactory cut which is not perpendicular to the axis of wheel rotation.

Various wheel shapes have been employed in an endeavor to surmount these difficulties. For example, it has been contemplated to provide a cutting-off grinding wheel having reentrant side faces which taper from the wheel periphery to the central wheel portion in order to provide sufficient wheel clearance and prevent any tendency of binding of the wheel within the work. However, due to the inherent friability of a relatively thin cutting-off grinding wheel, it has been necessary to make wheels of this type verymuch 10 wider with the consequent result of wasting of material cut off and a much slower cutting operation.

It has further been contemplated to provide spaced grooves or indentations in the opposed 15 parallel fiat side faces of a cutting-01f wheel to aid in cooling it during grinding, but none of these expedients has offered suflicient improvements to permit a wheel to be operated within its maximum cutting ability. Furthermore, grooves and indentations in the opposed wheel faces have served to weaken the wheels and prevent a high rotating speed.

It is, therefore, the primary object of this invention to provide a grinding wheel capable of cutting on its periphery and at the same time abrading the side face of a work piece sufficiently to prevent excessive heating and breakage of the wheel. 4

It is a further object of this invention to provide a thin cutting-off grinding wheel having a side face of predetermined roughness composed of a layer of projectingabrasive grains which may be of any desired shape and size, irrespective of the size and shape of the abrasive grains within the main body portion of the wheel.

It is a still further object of this invention to provide a method of making such a cuttingoff grinding wheel which may be easily and economically practiced and which serves to provide a highly efficient wheel capable of abrading the side faces of a work-cut during a grinding operation to preventthe wheel from overheating and binding therein.

The accompanying drawing illustrates a cutting-oil. wheel having rough abrasive faces on both sides thereof, but it will be understood that the invention applies equally well to any grinding wheel having only one rough face.

In thedrawing: I

Fig. 1 is a perspective view, partly broken away, to show the preferred embodiment of this invention; and

Fig. 2 shows one method of producing m preferred type of cutting-oil wheel.

According to this invention, I have provided a special type of grinding wheel which is particularly adapted for grinding up' to a shoulder on a work piece or for use as a cutting-off wheel which is required to produce deep, narrow cuts and/or cut off lengths of work. Such a wheel may comprise a main body portion of suitably bonded abrasive grains and a side face composed of a sheet or layer of material carrying abrasive grains thereon which provide sharp, free cutting edges projecting therefrom. In my preferred type of invention, a cutting-off wheel is provided with rough side wheel faces composed of any suitable sheets of abrasive material, such as an abrasive coated paper or other suitable fibrous material, which may be cemented to the side faces of the main body portion of the wheel and form an integral part therewith.' The fibrous material preferably comprises a very thin, porous, waterproof paper which may be integrally bonded to the main body portion of the wheel by the bond employed therein. The fibrous material also serves the further purpose of strengthening the cutting-off wheel as well as to secure the sharp cutting abrasive grains on the side wheel faces and provide opposed rough wheel faces composed entirely of sharp abrasive cutting edges projecting therefrom. If desired, these surface abrasive grains may be oriented when they are located on their fibrous backing so that their major axes will be opposed to the wheel faces and provide wheel faces composed solely of long, sharp, protruding abrasive cutting teeth projecting therefrom.

The abrasive grains on the side wheel faces may be of any desired shape and size irrespective of the shape and size of the abrasive grains bonded within the main body portion of the wheel.

As illustrated in the accompanying drawing, the preferred type of .my invention comprises a laminated disk type of cutting-off wheel l0 having two opposed side faces II and I2 of a predetermined roughness and, cutting ability and a peripheral grinding face I3 which is very narrow in comparison to its diameter. The main body portion of my grinding wheel is composed of an annular grinding member l4 comprising abrasive grains, such ,ascrystalline alumina or silicon carbide, of suitable size and of a Work cut at an extremely rapid rate as the wheel enters therein and thereby offer sufiicient clearance for the wheel to provide a fast, free cutting grinding wheel capable of feeding into the work at its maximum peripheral cutting capacity without overheating or causing damage to either wheel or work. In order to provide a wheel having such rapid, free cutting ability, the main body wheel portion M has its sides coated with layers or sheets of sharp abrasive material l6 which are integrally secured thereto and serve to provide opposed rough side wheel faces composed entirely of sharp projecting abrasive grains which may be of any desired size and shape irrespective of the size and shape of the abrasive grains within the main body portion ll. Hence, the side wheel faces may be constructed to abrade the sides of the work cut an abrasive coated paper or any other suitable abrasive coated fibrous support which may be integrally bonded to the sides of the main wheel body portion M. This material is preferably very thin and porous, so that the cementing or adhesive material employed to secure it in position may enter the pore structure and integrally unite the surface abrasive grains in position to provide side wheel faces composed entirely of sharp cutting abrasive teeth, each of which has one or more protruding unobstructed free cutting edges arranged to abrade the sides of a work cut as the wheel enters the work.

If desired, the abrasive coated fibrous ma-.

terial forming the side wheel faces l6 may be manufactured in such a manner that the individual abrasive grains are oriented and thereafter secured in position'with their major axes opposed to their support, as disclosed in the U. S. Patent to Schacht No. 1,854,071. It will be appreciated that a construction of this type will provide opposed wheel faces of maximum roughness which are composed entirely of a ployed in awet grinding operation, if desired.

and the cementing material which secures the coating of abrasive grains thereto may comprise any suitable adhesive. which will resist heat of grinding and the moisture of a wet grinding operation and integrally secure the layers Hi to the main body portion [4.

The sheets of abrasive material l6 may be suitably secured to the sides of the main body portion H by means of a cementitious'or adhesive material which intimately secures them as integral members therewith. In my preferred construction, the rough wheel sides l6 are integrally secured to the main body portion of the wheel by the same bonding material which secures the central abrasive grains into an integral grinding unit. However, it will be appreciated that these abrasive side faces may be suitably secured in position by means of any It is not insuitable cementitious material. tended, however, that the scope of this invention be limited to a grinding wheel having side faces composed of abrasive coated fibrous material. The present invention relates to an abrasive wheel having any suitable sheets of abrasive material applied to the sides of the main body portion of the wheel by means of suitable adhesive or bond whereby the projecting abrasive grains forming side wheel faces IE will be integrally united therewith.

One convenient method of producing my pre ferred type of grinding wheel is illustrated in Fig. 2 wherein a rigid bed 25 is arranged to support a press plate 26, retaining ring 28, and a hub -30. For convenience of assembly, the hub 30 and the retaining ring 28 slidably engage the press plate 26. A disk of sheet abrasive material such as an abrasive coated fibrous material 32, and preferably an abrasive coated waterproof paper having a layer of abrasive grains of de- I able organic bonding material, is then placed.

within the space between hub 30 and retaining ring 28 and in engagement with the abrasive disk 32. A second abrasive disk similar in shape and construction to disk 32 is then lo-' cated between hub 30 and retaining ring 28 with its fibrous support in engagement with the central annular body 34 of abrasive and bond. thereby forming a laminated grinding wheel assembly having a central portion of abrasive and bond which is flanked with side faces composed of layers of abrasive grains separated therefrom by thin sheets of fibrous material. A top press plate 38, slidably engageable with hub 30 and retaining ring 28, i placed upon disk 35 in engagement with abrasive coating thereon and suflicient pressure and heat are applied in any well-known manner to cause the bonding material within the central wheel portion 34 to soften and flow through the entire assembly and thereafter become matured, intimately uniting the abrasive disks 32 and 35 and forming an integral grinding wheel structure having the main body portion l4 flanked with thin side faces l6 (Fig. 1) composed entirely of sharp.

projecting abrasive grains which are of any desired shape and size irrespective of the grains within the main body portion of the wheel.

It will be appreciated that in a grinding wheel of this type, side faces may be provided having any desired cutting ability. Hence, the

side'faces of the wheel may be arranged to abrade the work at a sufiiciently rapid rate to provide a cutting-off wheel capable of feeding into the work at its maximum peripheral cutting ability. without danger of binding or overheating. Various modifications in structure and in method of manufacture will be apparent to one skilled in the art, and the claims are to be interpreted broadly within the scope of this disclosure.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding wheel comprising a main body portion of bonded abrasive grainsshaped in the form of a disk, and a separately manufacsive grains having two opposed side faces and a peripheral face, and a thin sheet of abrasive coated fibrous material cemented to each of the opposed side faces, forming rough wheel faces composed principally of sharp, projecting abrasive teeth which abrade the side faces of the work cut during a grinding operation and prevent binding of the wheel therein.

4. A cutting-off grinding wheel adapted for producing deep, narrow cuts comprising a 5 bonded abrasive disk-shaped central body portion of bonded abrasive grains having two opposed side faces and a very narrow peripheral face in comparison to its diameter, a thin, diskshaped sheet of waterproof fibrous material cov- 10 ering each'side wheel face and integrally secured thereto by the same bond as that used in the central body portion, and layers of sharp abrasive grains cemented to the fibrous material which provide opposed rough side wheel faces 15 composed principally of closely spaced, sharp, abrasive cutting edges projecting therefrom, serving to abrade the sides of the work cut and prevent binding of the wheel therein during rinding.

5. A cutting-off grinding wheel adapted for producing deep cuts comprising a disk shaped main body portion of bonded abrasive grains," and opposed rough side wheel faces composed of sheets integrally united therewith which have 25 layers of abrasive grains bonded thereto with their major axes projecting outwardly from the wheel faces and providing closely spaced, sharp cutting abrasive teeth projecting therefrom.

s. A cutting-off grinding wheel adapted for to producing deep cuts comprising a disk shaped ,main body portion of bonded, abrasive grains,

' face and providing closely spaced, sharp cutting teeth evenly disposed over theentire wheel face. 40 '7. The method of producing a grinding wheel comprising the steps of providing a disk of fibrous material having a coating of abrasive grains integrally cemented thereon and sharp cutting abrasive teeth projecting therefrom, placing a layer of an unmatured mixture of abrasive grains and a bond in engagement with the sheet of fibrous material, and subjecting the assembly to the influence of suflicient heat and pressure to cause the bondto unite the entire mass together as amintegral inember and providea grinding wheel having a rdugh'side face composed principally of projecting abrasive grains having free cutting edges.

8. The method of producing a cutting-oi! grinding wheel comprising the steps of providing two. thin disks of sheet fibrous material, each' of which has a coating of abrasive grains integrally cemented thereon and sharp abrasive cutting edges projecting therefrom, placing an annular body of an unmatured mixture of abrasive grains and an organic bond between the sheets of fibrous material, and subjecting the assembly to the influence of sufiicient heat and pressure to cause the bond to unite the entire mass as an integral member and provide a thin grinding wheel having opposed rough side faces composed principally of projecting tooth-like abrasive grains having free cutting edges.

9. The method of producing a grinding wheel comprising the steps of coating a disk of thin fibrous material with an adhesive, depositing a layer of granular abrasive material thereon, orienting said abrasive grains so that they are integrally secured to the fibrous support with their major axes projecting outwardly therefrom, placing an unmatured mixture of abrasive grains and bond in engagement with the fibrous material to form the main body of the wheel, and subjecting the assembled material to the influence of sufficient heat and pressure to unite the entire mass and provide a grinding wheel having a rough side face principally composed of projecting abrasive grains which may be of any desired size and shape irrespective of the abrasive grains within the main body portion of the wheel.

10. The method of producing a cutting-off grinding wheel comprising the steps of coating a sheet of thin, porous fibrous material with adhesive, depositing a layer of granular abrasive material thereon, orienting the abrasive grains so that they are secured to the fibrous support with their major axes projecting outwardly therefrom, shaping the coated fibrous material in the form of two disks, each of which has the diameter of the desired grinding wheel, placing a body of an unmatured mixture of abrasive grains and an organic bond in engagement with the fibrous disks, and subjecting the assembly to the influence of sufilcient heat and pressure to cause the bond to flow into the pores of the fibrous material and intimately unite the entire 10 shape and size irrespective of the shape and size 16 of the abrasive grains within the main body portion of the grinding wheel.

DUANE E. WEBSTER.

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