Improvements in or relating to Grinding and Polishing Metal Bodies to Reduce them to True Spherical Form.
Year: 1898

page_text: Date of Application, 12th July, 1898-Accepted, 13th Aug., 1898
Improvements in or relating to Grinding and Polishing Metal Bodies
to Reduce them to True Spherical Form.
A communication by GEORGE H. HATHORN, of Bangor, in the County of Penobscot,
and State of Maine, United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, 118, New Street, Birmingham, in the County of War-
wick, and 322, High Holborn, in the County of Middlesex, Civil Engineer, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement-
-
This invention relates to machines for and method of grinding and polishing
metal bodies to reduce them to true spherical form and consists in features, details
and combinations hereinafter recited.
The accompanying drawings illustrate the preferred form or embodiment of
this invention, which will be explained in connection therewith.
Figure 1 is a sectional elevation of the improved machine with the cover or hood
thrown back to afford access to the interior of the containing vessel, and with
the annular plate or disk removed.
Figure 2 a perspective view of said annular plate detached.
Figure 3 a sectional view of the main operative parts in working relation.
Figure 4 a perspective view of the lever or yoke by which the hood or cover is
lifted.
Figure 5 an elevation, partly sectional of the spindle, step and clutch.
Figure 6 a sectional view of an antifriction step.
Figure 7 a sectional view of the rotary disk and its hood or cover, in slightly
modified form.
Figure 8 an enlarged perspective view of the antifriction step showing the parts
separated, and some of them in section.
In these drawings, A indicates a framework, which may advantageously be
formed of cast iron, though wood or other materials may be used in whole or in
part. The horizontal or cross members of this frame are provided with boxes or
bearings 6 6, as in Figure 1, or with a step bearing and guide box b, as in
Figure 5 to carry a vertical shaft or spindle B.
In Figure 1 the spindle or shaft B is represented as furnished with a bevelled
wheel C which receives motion from a similar wheel C¹ carried by a horizontal
shaft D.
The wheels CC₁ may be provided with teeth, or they may be friction wheels, as
preferred.
E indicates a lever provided with pins or studs f, which entering a circumferential
groove in a collar c carried by the spindle B, serve to raise or lower the spindle
as the lever is elevated or depressed, so that the wheels C C¹ may be carried into or
out of contact and the machine be accordingly started or stopped at will.

page_text: Keyed, screwed upon, or otherwise secured to shaft or spindle D is a disk or
plate F, the periphery of which is shouldered as seen in Figure 1 to afford a center-
ing bearing and support for an annular plate or disk K, which rests thereon as
shown in Figure 3, and is held in locking engagement therewith by pins e e or
equivalent studs or projections, extending from one of said parts into recesses in
the other.
In Figures 2 and 3 the disk or plate K is represented as a flat or horizontal
plate, with a continuous spiral channel or groove in its face, and this is the pre-
ferred form but it may be made dishing, or with upwardly inclined face, as in
Figure 7, and channelled as in Figures 2 and 3 or smooth as in Figure 7.
So too,
the spiral groove or channel may be provided or omitted when the plate is flat,
and when provided, will disappear in a comparatively short time through wear.
Above the disk or plate K or K¹ is a hood or cover Hor H', the depending skirt M
or M¹ of which encircles the periphery of said disk or plate, as shown in Figures 3
and 7, the inner surface of said hood being formed with a spiral groove or channel
as shown in both figures.
The direction of the spiral of the groove should in all cases be such that when
the disk or plate K or K¹ is rotated in its prescribed direction, bodies lying upon
the disk shall traverse said groove or channel and be thereby guided outward, or
in other words, the centrifugal force due to rapid rotation of the disk tends to
throw the bodies outward and the spiral groove or channel of the plate operates
to determine the rate of outward movement.
In moving outward the bodies roll over and over in the direction of the length
of the groove or channel, and are also caused by the outward pressure and move-
ment, and the movement of other bodies against and over them, to change their
axes of rotation, so that all sides are ground. In this way, and in a very short
time, comparatively speaking, bodies of irregular shape are rendered truly
spherical.
Owing to the fact that these bodies rest upon the plate or disk K or K¹ they
necessarily partake in a measure of its motion about its axis, hence when they
leave the periphery of the disk they tend to follow after it some distance particu-
larly as they make contact with the skirt M or M¹ before losing contact with
disk K or K¹.
If the disk K be flat, there will be no tendency of the bodies reaching its edge
to rise unaided, though if the disk be dishing, as in Figure 7, an upward direction
will be imparted to them.
To ensure such upward movement whether the disk be flat or dishing, and to
prolong the grinding action in the inner face of the skirt M or M¹ a spiral groove
or channel is preferably formed running in such direction relatively to the
direction of rotation of the disk that bodies entering said groove shall be caused to
ascend the spiral by reason of the momentum acquired in moving with the disc.
The action is a peculiar one, the bodies lying upon the disk partaking of its motion
in considerable degree, but not moving at the same velocity, owing to the slipping
or sliding of the disk beneath and relatively to the bodies thereon. The speed
acquired by the bodies thus carried will vary with their nature, but in the present
case may, it is thought, be reasonably assumed to be from a third to a half of that
of the portion of the disk lying immediately beneath.
Whatever the relation may be in fact, the velocity acquired by the bodies is
sufficient to cause them to ascend the spiral channel or groove of the hood to a
considerable height, varying with the character and the degree of finish of said
bodies, and the abrading or polishing materials carried with them.
If the skirt M or M¹ be of considerable depth, the bodies may ascend only part
way up the same and then fall back; but if it be shallower they may pass above
the skirt and travel around the indrawn or converging walls of the hood a greater
or less distance, until their momentum is so far reduced that they will fall back
to the disk K or K¹.
Whatever be the character or extent of the action the bodies are repeatedly

page_text: carried outward and then fall or roll inward, sometimes directed by the hood and
sometimes rolling back over the accumulation at the circumference of the disk;
but in all cases being subjected again and again to the action of the disk.
°
Extended use of the machine has demonstrated its great capacity and efficiency.
For convenience in applying and removing the hood or cover, and for the pur-
pose of maintaining it in proper working position between two upright arms J, J
of the frame A a lever L is hinged or pivoted provided with ears h, and with a
hand-hole j; and the hood or cover is formed with lugs or hooks d to engage over
the ears h, as seen in Figures 1 and 3. The ears are perforated or socketed, as
seen in Figure 4, to receive fastening screws or bolts should these be deemed
necessary.
At the side of frame A opposite that at which the lever L is hinged, to another
arm J of the main frame a bail I is pivoted or hinged carrying a screw and hand-
wheel u.
When the lever L is brought over the frame to lower the hood or cover to place,
the bail I is swung up over its end or hand-hold j¹, and the screw is set down
sufficiently to hold the lever rigidly in position, its lower side resting upon the
arm J, which thus serves as a stop or gauge to determine its position.
The foregoing description is based mainly upon the manner of mounting and
actuating the shaft illustrated in Figure 1. For the purpose of reducing friction
and vibration it is preferred to mount the shaft or spindle on an antifriction step
of the construction illustrated in Figures 5, 6 and 8, also allowing to the spindle
a limited amount of play in its guiding or supporting box b after the manner of
the spindles of centrifugal separators or extractors.
As shown in these figures, the spindle B has at its lower end an enlargement m,
represented in the form of a block screwed thereon and having a central cavity
or depression. The lower face of the enlargement m is also recessed to receive a
hardened steel plate i, in which is formed a circular groove or track to receive
antifriction balls or rollers n. Directly beneath the balls n and constituting a
track or bearing therefor, is a steel plate or disk 7, which in turn is supported by
a series of balls or rollers o, traversing a circular groove in a steel plate 2', seated
in a disk or block j having on its under side a rounded central projection which rests
in a corresponding but larger depression in a step plate p. This latter plate p,
made fast to the frame A or to the floor on which it stands, and is furnished with
a cup k, which rises somewhat above the lower end of block m as seen in Figures 5
and 6.
is
The cup serves to hold a supply of oil, which is preferably kept at a sufficiently
high level to submerge the lower series of balls or rollers o, or it may rise to or
above the second series.
Rising from the centre of the disk or block j is a tube q, the sides of which are
perforated, and the lower end of which encircles or encompasses the upper ends of
passages r, formed through the disk or block j. Other openings s, through said
disk pass to the outside of the tube and to the space between it and the central
opening of the plate i¹, which, like that of the plates i and 7, is somewhat larger in
diameter than tube q.
Under this construction of parts a constant circulation and distribution of oil is
effected, the oil tending to rise by capillary attraction within tube and between
it and the encircling walls of the openings in the several plates, aided by the suction
due to the outward movement of the oil over the several disks through centrifugal
force, and to the natural tendency of the oil to flow back to the centre and to rise
to replace that thrown off. In moving outward over the disks the oil is supplied
to both sets of balls or rollers and to the tracks which they traverse, and in this
way perfect lubrication is effected and maintained.
When the stepped spindle is employed, it is provided with a loose band wheel N,
having its hub provided with clutch teeth to engage with similar teeth of collar c,
which, under this arrangement of parts is free to move a limited distance vertically,

page_text: but is caused to rotate with the shaft by a connecting spline or feather t. The
lever E serves under this arrangement to raise and lower only the collar c, and thus
to uncouple or to couple the band wheel and shaft to stop or start the machine.
The lever E may be retained in its different positions by any usual form of
rack or holding device.
To collect the oil and abrading materials used in the machine and thrown off
at the periphery of the disk through centrifugal force, a pan G is provided the outer
walls of which rise above the lower edge of skirt M or M' of the hood or cover.
The central opening through which the shaft or spindle passes also has an upturned
flange or wall, to prevent escape of oil at that point. Finally, to prevent oil etc.
following down the under face of disk K or K¹ and the shaft or spindle B, a disk O
is applied to the latter, below disk K or K¹, and preferably of the form indicated
in Figure 7. Whether the speed be sufficient to throw off the oil by centrifugal
force, or it drip from the disk by gravity, it will fall beyond the flange or wall g
and be received and retained within the pan G.
In the foregoing description the enlargement m has been spoken of as made
separate from and secured to the spindle B, and the plates i and i¹ have also been
described as being made separate and removable, but these features while con-
sidered desirable, are not essential.
As the skirt M or M¹ requires to be redressed somewhat frequently, and wears
away much more rapidly than the top of the cover, it is preferred to make it
separate from the top, and to form the parts with interlocking shoulders as in
Figure 7. Obviously, any equivalent means of connection may be provided.
The interposition of the disk F between the disk or plate K or K¹ and the
spindle B, permits the ready removal of the disk for re-dressing or for the sub-
stitution of another disk, and this provision is quite desirable, but it is obvious
that the machine will operate satisfactorily without this special construction.
It is of course understood that the parts H¹, K¹ and M are the mechanical
equivalents of the parts H, K, and M, and the claims are to be read and under-
stood accordingly.
The skirt or wall M may be flared slightly outward, and it is not desired to
restrict the invention to the precise forms shown, the essential feature of the
invention being to cause the bodies to travel upward and then to return to the
centre as above set forth.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is:-
1. In a machine for grinding and polishing, the combination of a disk or plate
rotatable about a vertical axis; and a fixed encircling skirt or body having a
spiral groove or channel rising from the disk in the direction of rotation of the
latter.
2. In a machine for grinding and polishing, the combination of a disk having
in its face a spiral groove adapted to receive and guide the bodies to be ground
or polished; and means for imparting to the disk a high speed of rotation; an
open or unobstructed space being left above the disk to permit the free rise and
fall of the articles placed thereon, and to enable them to freely change their axes
of rotation.
3. In combination with a spirally grooved or channelled disk and with means
for imparting rotation thereto; a fixed encircling wall to arrest bodies thrown off
from the disk and to return them thereon.
4. In a machine for grinding and polishing, the combination of a spindle; a disk
or plate carried thereby and having a spiral groove or channel formed in its face;
means for rotating said spindle and disk; and a hood or cover having its skirt
arranged to encircle the disk and provided with a spiral groove or channel rising
in the direction of rotation of the disk.
5. In combination with spindle B and disk F secured thereto, detachable annular

page_text: disk or plate K carried by disk F; and hood or cover H encircling and covering
the disk F, substantially. as described and shown.
6. In combination with shaft or spindle B, and step plate p, the antifriction
bearing, consisting of block or enlargement m and plates or disks and j with balls
or rollers interposed between proximate faces, substantially as and for the purpose
set forth.
7. In combination with spindle B and parts i, Z and j, the latter provided with
perforations; tube communicating, with said perforations; and cup k encircling
said parts, substantially as and for the purpose explained.
8. In a machine for grinding and polishing, the combination of a horizontal
disk; means for rotating said disk; and a hood covering and encircling the disk
and having a spirally grooved skirt detachable from the top, substantially as and
for the purpose explained.
9. The art or method of grinding and polishing bodies to reduce them to true
spherical form, which consists in moving them upward by centrifugal force over
a supporting surface, together with abrading or polishing material, returning
them toward the axis of motion, and repeating the operation until the required
condition is attained.