US2826878A

US2826878A - Grinding wheel

Info

Publication number: US2826878A
Application number: US531433A
Authority: US
Inventors: Frederick W Lindblad
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-08-30
Filing date: 1955-08-30
Publication date: 1958-03-18
Anticipated expiration: 1975-03-18

Description

March 18, 1958 I F, w. LINDBLAD I 2,826,878

GRINDING WHEEL Filed Aug. 50, 1955 United States Patent This invention relates to grinding wheels which are suit able for grinding laminate materials and other materials which produce uneven wear on the face of the grinding wheel.

In the grinding of the edges of safety glass with a "conventional grinding wheel, a grooveis often Worn in the central portion of the wheel. This changes the resulting contour of the ground edge of the glass being worked upon, which is objectionable. In addition, this necessitates a replacement of the wheel before the major portion of'the abrasive wheel rim has been used.

'The uneven wear on the grinding wheel is perhaps initiated by the smudging of the plastic lamina of the safety glass, softened by the heat of friction, during grinding. Abraded material, including glass particles and, perhaps, powdered parts of the wheel that have been worn away, adhere to the tacky portions of the lamina and thereby produce an abrading compound embedded in the plastic which tends to wear away the grinding wheel atthe place where the plastic lamina is located in the safety glass. Regardless of whether or not that is the, explanation for the uneven wear on the'grinding wheel, the fact is that uneven wear does take place, and is objectionable.

his one of the objects of this invention to provide a grinding wheel in which the wear on the wheel is more evenly distributed when the wheel is used for laminate bodies wherein the laminae have varying abrasive qualities, or where other conditions exist which ordinarily provide for uneven wearing of grinding wheels of .the type heretofore used.

The abrasive rims of grinding wheels are often formed of a number of circumferentially spaced abrasive segments wherein opposed faces of adjacent segments are spaced apart to leave clearance spaces for removal of ground particles from the grinding surface of the wheel. The clearance spaces create agitation of the air or coolant which-aids in removal of the ground particles from between the segments. The difiiculty with this design is that vibration and chattering of the grinding wheel frequently results, perhaps due. to the intermittent contact between the grinding wheel and the work piece.

It is therefore another object of this invention to provide a grinding wheel wherein the grinding surface of the wheelis designed to maintain continuous contact with a work piece, while yet providing a number of clearance spaces for removal of ground particles from the grinding surface of the wheel. a

In accordance with a preferred form of the invention,.

the abrasive rim of the grinding wheel is formed of a number of substantially identical, separate abrasive'segments which are in contact along a portion of their width, and which are separated along other portions of their width to provide clearance spaces for the passage of ground particles in the periphery of the grinding wheel. For particular grinding applications where uneven wearing has been a problem heretofore, spacing of the spaced portions of the abrasive-segments are-such that the over-' The grinding wheel there shown is similar to the grinding 2,826,878 Patented Mar. s, 1958 all angular extent of different axially spaced portions of the periphery of the grinding wheel vary in accordance with the abrasive qualities of the portions of the work piece with which they are to make contact. The result is that the same amount of material is removed from each portion of the body being ground for each revolution of the grinding wheel, resulting in even wearing of the grinding wheel. I

These and other objects, advantages and features of the invention will become apparent upon making reference to the specification to follow, taken in conjunction with the drawings wherein:

Fig. 1 is an elevational view, partly broken away, of a grinding wheel incorporating features of the invention;

Fig. 2 is an edge view of the grinding wheel of Fig. 1;

Fig. 3 is an enlarged fragmentary side view of a portion of the grinding wheel periphery of Fig. l;

Fig. 4 is a fragmentary enlarged end view of a portion of the grinding wheel periphery of Fig. 1;

Fig. 5 is a section through a portion of the grinding wheel periphery, taken along section line 5-5 in Fig. 4;

Fig. 6 is a fragmentary edge view of a portion of a modified abrasive grinding wheel;

Fig. 7 is a section through the portion of the grindin wheel of Fig. 6, taken along section line 77;

Fig. 8 is a fragmentary edge view of a portion of another modified form of grinding wheel; and

Fig. 9 is an end view of a still further modified form of grinding wheel.-

. In the drawings like reference numerals indicate like elements throughout.

The grinding wheel 1 shown in Figs. 1 through 5 comprises a number of separate, abutting, abrasive segments 3 assembled to form a wheel-like grinding surface. The segments are secured together by a frame 5 which includes a pair of spaced, circular opposed disk sections 77 which define therebetween a peripheral outwardly facing channel 9 which receives the abrasive segments 3. The abrasive segments are held in place within the channel 9 as by pins 11 which pass through the wheel disks 7-7 and through the abrasive segments. The wheel frame is secured to a hub 13 which is connected to a shaft 14 suitably journalled for rotation in any conventional manner.

The opposed ends of the abrasive segments are beveled to form a series of discontinuities 15 in the abrasive surface of the grinding wheel between-adjacent abrasive segments. In Figs. 1 to 5, the beveling of the edges of each segment leaves a flat 17 which lies in a plane that includes the axis of rotation of the shaft 14. The flat 17 at each end of each segment is abutted and overlaid bythe corresponding flat of the adjacent segment along the entire thickness of the segment. The opposed radial surfaces of the abrasive wheel segments lie along radial lines 18. The angle of the radial line 18 with respect to a plane at right angles to the axis of rotation of the wheel determines the rate of diminution of the periph-- eral extent of the wheel along sections spaced axially from the flat 17. The grinding wheel 1 having the V- shaped discontinuities 15 will evenly grind a body which In the preferred form of the invention, adjacent siegments 3 are in contact to provide a continuous grinding wheel surface which maintains continuous contact with the body to be ground, to eliminate chattering or undue vibration of the grinding wheel.

Figs. 6 and 7 show a modified form of grinding wheel-l p.osing:faces; of the segments are beveled through to the. center line of the segments so that adjacent segments make merely a line contact. Successive axially spaced segments on opposite sides of the center of the rim are therefore incontact with the work piece for gradually decreasing lengths. of time for each revolution of the wheel.

Fig. 8 shows a still further modified form of grinding.

wheel. in. having abutting segments 3a (which correspond to the respective segments 3 of Fig. 1) with generally V-shapedend faces 20a forming diamond-shaped discontinuities lie between the segments. The end. faces are beveled. to. provide axially spaced peripheral rim portions. of. the samev respective angular extents-as the wheel. rim is evenly worn away. it can be seen that the abrasive rim of the wheelmaltes contact with a work surface for progressively greater. amounts of time per revolution proceeding outward from the center portion thereof. This embodiment is used to grind a surface where the abrasive forces applied to the grinding wheel are greatest at the extremities of the wheel rim and gradually diminish toward the medial portion thereof.

In the modified form of wheel 1b in Fig. 9, the ends of each of the segments 3b (which correspond to the segments 3 of Fig. 1). have rectangular projecting portions 21 in the medial regions thereof providing rectangular discontinuities 15b15b on the outside of the wheel rim. Thus, the medial portion of the rim makes contact with the work surface for a greater period of time than the outer portion of the rim.

In each of the different embodiments herein described the grinding wheel includes a series of arcuate abrading segments, for instance, twenty-four segments secured together as in Fig. 1. In each instance, adjacent segments are in contact with one another along a line or a plane that extends radially of the center of rotation of the grinder. In each instance there is separation of adjacent grinding segments if a section is taken at right angles to the axis ofrotation of the wheel and at a location spaced axially of the place of contact of the adjacent segments. In each instance the separation tapers in a direction radially of the wheel so that in any planar section, taken in a plane at right angles to the axis of rotation of the wheel; the ratio of the sum of the peripheral extents of the grinding segments to the sum of the peripheral extents of the spaces between the grinding segments remains con stant as' the grinding segments are worn down. The arcuate extent of the grinding surface varies in different spaced planes taken through the grinding wheel at right angles to the axis of rotation thereof, the variation being in proportion to the differences in the amount of abrading action that would take place upon the wheel itself at different axially spaced portions thereof if the segments were in contact with one another throughout their full axial width.

In compliance with the requirements of the patent statutes Ihave here shown and described a few preferred embodiments of my invention. It is, however, to be understoodthat the invention is not limited to the precise constructions here shown, the same being merely illustrative of the principles of the invention. What I consider new and desire to secure by Letters Patent is:

1. A grinding wheel for use in grinding a work piece wherein different portions thereof that are ground simultaneously have different wearing effects on the abrasive of the wheel, said wheel comprising an abrasive rim having different abrading wheel portions that abrade the different portions of the piece to be ground simultaneously. said abrading wheel portions being respectively of different circumferential extents lying in. a common plane with and transversely of the periphery of said rim, and the ratios of said circumferential extents being a function. of

i '4 the ratios of the wearing effects of the piece ground at said different portions thereof.

2. A grinding wheel having an abrasive rim with discontinuities formed in the abrading face thereof having progressively different total pcripheral angular extents at different portions of the rim, so that one grinding section of the wheel makes contact with said body for a longer time in a revolution of the wheel than another grinding section.

3. A grinding wheel such as is defined in claim 2 wherein the section of the wheel that makes maximum contact with the work during each revolution of the wheel is the portion that lies in a plane located at right angles to the axis of rotation of the wheel and midway between the edges of the abrading face of the wheel.

4. A grinding wheel for grinding a body where the abrasive effect of the body on the wheel. varies across the abrading face of the wheel, comprising an. abrasive rim: having a number of separate, identical, peripheral segments in spaced relation about the axis of rotation of the wheel and adapted to make successive contact with a portion of the'body to be ground, each of'sai'd segments having axially. spaced portions which vary in overall: angular extent. about the wheel axis so that different corresponding axial sections of the wheel are in contact with a given portion of said body for different lengthsof time for each revolution of the wheel.

5. A grinding wheel. for grinding a body where. the abrasive effect of the body on the wheel varies across the abrading face of the wheel, comprising a rim of abrasive material havingv axially spaced abrading sections.

which have. different respective overall abrading qualities, adjacent. ones of said sections being in contact along, only a portion of their opposite ends the average abrasive effect per inch of circumferential extent thereof being respectively different and a function of the. abrasive effect ofthe. portions of said body which are contacted thereby.

6. A grinding wheel including an abrasive rim which has a continuous abrasive portion extending completely about the axis of rotation of the wheel so that the rim maintains continuous contact with the workpiece being ground, and a series of discontinuous portions formed in the abrading face of the wheel which provide clearance spaces for particles removed from the work piece.

7. A grinding wheel. including a number of separate, abrasive, grinding wheel segments spaced about. the axis of rotation of the wheel so that the segments make successive contact with a work piece being ground and adjacent segments being fiush in contact along a portion of the width of the abrading surfaces thereof, whereby the grinding wheel is in continuous contactwith the work piece, and a portion of adjacent segments being spaced apart along their opposed abrading surfaces an amount to provide clearance for the passage of abraded particles.

8. A grinding wheel as defined in claim 7 further characterized in that said spacedapart portion opens through opposite sides of said segments to produce a maximum abrasive effect in those portions of said adjacent segments in contact with each other and diminished abrasive effect outwardly of said contacting portions.

9. A grinding wheel as defined in claim 7 further characterized in that said spaced apart portion defines a discontinuity therebetween and opening through the abrading surface at a location between the adjacent segment portions at which they are in contact to produce a diminished abrasive force in the medial portion of said wheel and a maximum abrasive force outwardly of the medi'al'portion.

10. A grinding wheel comprising a series of separate abrasive grinding wheel segments, means securing, the segments together to form a grinding wheel, each segment having successive peripheral abrasive portions across the grinding face of the wheel which fall. along the same respective. circles as the. corresponding portions of. the

other segments, and. adjacent segments contacting each other along at least one pair of said corresponding portions thereof and other corresponding portions of adjacent segments being spaced apart.

11. A grinding wheel for use in grinding a work piece wherein different portions thereof that are ground simultaneously have different wearing efiects on the abrasive. of the wheel, said wheel comprising an abrasive rim having a plurality of circumferentially spaced discontinuities in the abrading face thereof to define therebetween abrasive portions on said rim, said abrasive portions being of respectively different circumferential extents, and theratios of said circumferential extents being a function of the ratios of the Wearing effects of the work piece ground at said different extents of said portions.

12. A grinding wheel having an abrasive rim with sets of discontinuities formed in the abrading face thereof having different total peripheral angular extents at different portions of the rim, so that one grinding section of 6 the wheel makes contact with said body for a longer time in a revolution of the wheel than another grinding section, the sets being spaced from one another around the periphery of the wheel and the discontinuities of each set being opposite one another axially of the wheel and each tapering to and ending at a point which is midway of the width of the wheel.

References Cited in the file of this patent UNITED STATES PATENTS 875,935 Landis Jan. 7, 1908 1,422,200 Harris July 11, 1922 1,783,729 Larsson Dec. 2, 1930 2,032,362 Herman Mar. 31, 1936 2,256,120 Lovenston Sept. 16, 1941 2,467,878 Beth Apr. 19, 1949