US1711042A - Scroll wheel - Google Patents

Description

April 30, 1929. l E A CHASE 1,711,042

SCROLL WHEEL Filed July l2., 1926 Patented Apr. 30, 1929.

N UNITED STATES ELROY A. CHASE, OF NORTHFIELD, VERMONT.

SCROLL WHEEL.

Application led July 12,

rlhis invention relates to a grinding Wheel having grinding;l members oi' a general Scrolllile form. The scroll type of Wheel has been heretofore commonly used for grinding flat surfaces on blocks of granite and other similar material and it is the general object oli my invention to improve the construction et such scroll Wheels to the end that they may be more etlectively adapted to certain special grinding operations.

It is more specilic object ot my invention to provide a Scroll Wheel which will be particularly adapted to grinding blocks oi' granite having surfaces which are curved in one section and straight orilat in a Section perpendicular thereto. Such blocks are commonly but somewhat inaccnrately termed oval tops in the stone polishing trade.

ln grinding such curved surfaces, the grinding Wheel makes only a line contact vvith the stone and the Wear of the Wheel is quite different from that which occurs in grinding a Hat surface. The amount of surl'ace to be ground with line contact is substantiallythe same at all radial distances from the axis of the Wheel, While the area ot' the grinding surface or the Wheel commonly increases with the radial distance .from the axis and the outer portions of the wheel are also rotating at much increased speed.

A For this reason, oval tops7 have com-` monly been produced by other and more expensive methods such as the use ot surface cutters. Vilhcnever any one attempted to use the ordinary scroll or ring wheel on oval top Work, the wheel had a strong' tendency to become concave or dished at the center and the Work was apt to be corresponding'ly rounded or convex Where it should be iflat.

It is a further object of my invention to provide a scroll wheel so desig'nl-d as to substantially equalize the wear at diilerent radial distances Jfrom the axis ot the. Wheel. thereby preserving the flat grinding Surface olf the wheel. To the attainment ot this object, l provide a design ttor the scroll member-s which substantially increases the area or grindingl surface toward the center o'l the. Wheel. otlfsettinc' the greater circumference and higher speed at the periphery.

A tui-ther feature of the invention relates to the provision ot a series ot pockets in the inner Walls of Scroll members ot the type 1926. Serial No. 121,765.

described, by which provision the efficiency of the Wheel is still furtherincreased.

My invention further relates to arrange` ments and combinations of parts which will be hereinafter described and more particularly pointed out in the-appended claims.

Preferred forms of `the invention are shown in the drawings in which y i Fig. 1 is a bottom view oit ascroll Wheel embodying one form of my invention;

Fig; 2 is a top or plan View thereof;

F ig. 3 is a side elevation of the Wheel shown in Figs. 1 and 2, and

F 4 is a. bottom View of a. modification.

Referringr to Figs. 1 and 3, I have Shown a small scroll wheel preferably of cast iron, and comprising two scroll members connected by a cross bar 11 and also by Spots or tyingr elements 12. The cross bar 11 `is `provided with ears 13 adapted to receive a rocking member 14 pivoted on a cross pin 15 in the end of a drive shaft 16. y.

The grinding;r Wheel VVthus has a swivel connection with the drive shaft 1G and is held against the stone S by the direct pressure of the drive sha-ft against the ears 13.`

The Wheels may be removed and replaced by merely raising thedrive shaft out of the open bearings in the ears 13. i The scroll members 10 are of a special shape and construction which will now be described. The extreme outer end portion ot each member 10 iS substantially concentric With the axis of the wheel between the points a, and b (Fig. l), or for about a quarter of the circumference. The pio vision of these circular outer portions has been found very desirable for use on oval top work in which reverse curves are frequently encountered, as the cylindrical outer surfaces prevent the bumping or jarring action Which would otherwise occur when the edges of the scroll Wheel encountered a reversed curve portion ot the surface.

Each grinding element 10 is also gradually increased in etfective widthas the scroll approaches the axis of the wheel. The object of this increase in width, as previously pointed ont7 is to equalize the Wear ot' the Wheel when lgrinding a curved surface in which there is only line Contact, and in which the Wheel surface area operative at a tgiven point on the line of contact otherwise varies directly With the distance from the l axis. By increasing the width of the grind-` ing surface as it approaches the center, this variation in grinding action is substantially offset and a Wheel is produced which will Wear evenly and preserve its flat grinding face even when used on oval top Work with line contact only.

I further increase the eiliciency of my improved grinding Wheel by providing a series of pockets or sei-rations 17 on the inner faces of the grinding members l0. The outer Wall 18 of each pocket is preferably substantially concentric with the axis of the Wheel W and this construction facilitates the feed of the abrasive under the scrollshaped grinding members. A grinding Wheel constructtal as above described has been found very effective :tor the purposes indicated and is adapted to take the place of the much more expensive surface cutting operation which has been commonly used for producing curved or ov: l top surfaces.

In Fig. 4, I have shown a wheel having a single continuous scroll member but otherwise of the construction previously described. This Wheel may also be provided with pockets as in the form shown in Figs. l to 3.

l Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed otherwise than as set forth in the claims, but what I claim is l. A Wheel for grinding Stone having a. scroll-shaped grinding member, the grinding surface of which is gradually increased throughout the length of the scroll as said scroll member approaches the axis of the Wheel.

2. A Wheel for grinding stone having a scroll-shaped grinding member in which the average effective Width of grinding surface is constantly increased throughout the length of the scroll toward the axis of the Work.

3. A. wheel tor grinding stone having scroll-shaped grinding members in which the grinding surface ol' said members is increased in Width throughout the length ot the scroll toward the axis ot the Wheel, and in which the inner side faces of said memw bers are serrated.

t. A Wheel for grinding stone having a scroll-shaped grinding member7 the grinding surface of vwhich is gradually increased throughout the length. of the scroll as said scroll member approaches the axis ol the Wheel, and in which Wheel thc eXtreme outside portion of said member forms substantially the segment ol" a cylinder.

5. A wheel tor grinding stone having` scrollshaped grinding members, the grinding surfaces oit which are graulually increased throughout the length of the scroll as said scroll members apijiroacn the axis ot the Wheel, and in which pockets are pro- `-ided in the inner t'aees oi said members, the outer Walls ol said pockets being substantially concentric with the axis ot' said Wheel.

6. A wheel for grinding stone, comprising a plurality oit imlepeudent scroll shaped grinding members tied together by a crossbar, the grinding surfaces of each of said members being gradually increased throughout the length of thescroll as the members approach the axis of the Wheel formed by the members.

In testimony whereof I have hereunto ailixed my signature.

ELROY A. CHASE.

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