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Патент USA US3039246

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June 19, 1962
w. E. HOLT
3,039,241
FLOOR SURFACING MACHINES
\
Filed Jan. 18, 1960
45-4:72
1,
INVENTOR.
WILLIAM E. HOLT
BY
01lov
ATTORN EY
United States Patent
3,039,241
Patented June 19‘, 1962
2
1
3,039,241
[ice
FIG. 6 is an end view of the detachable drum cushion
,
FLOOR SURFACING MACHINES
William E. Holt, 669 20th St., Oakland, Calif.
Filed Jan. 18, 1960, Ser. No. 3,065
4 Claims. (Cl. 51-194)
The present invention relates in general to the construc
tion and operation of rotary surfacing elements, and more
particularly, to cylindrical hollow rotary drums particu
larly designed and especially useful in ?oor surfacing
machines for supporting and detaohably holding on its
circumferential surface a sheet of abrasive material.
‘In my prior Patent No. 2,437,958 is disclosed such a
rotary drum construction in which a drum cushioning ele
i'n-g element.
In FIG. 1 is illustrated a floor surfacing or sanding
machine of a well known type comprising a wheeled
housing 10 enclosing a rotary surfacing element 11
mounted on a horizontal axis and driven by an electric
motor 12 mounted on the housing. The motor 12 also
drives an exhaust fan 13 connected to a dust collecting
nozzle (not shown) adjacent the rear side of the surfac
ing element -11 and arranged to deliver the dust-laden
air to a dust bag (not shown). A hinged shield 16 ex
tends across the front of the housing and can be raised
from its operating position to permit access to the surfac
ing element.
ment consisting of two substantially semi-cylindrical rela 15 The surfacing element .11 comprises a hollow metal
drum formed by a cylindrical shell 17 of non-magnetic
tively thin spring steel plates forming a substantially
metal, preferably aluminum, closed at its opposite ends
rigid two-part metallic backing sheet shaped to ?t around
by circular end plates 18 and 19 ?tting therein and secured
the cylindrical surface of the drum and a continuous
thereto by screws or the like. A circumferential ?ange
layer or sheet of resilient material, such as sponge rub
20 on each end plate abuts the corresponding edge of the
20
ber, shaped to ?t around and coextensive with the outer
shell. The drum is rigidly mounted on a drive shaft 21
side of the metallic backing sheet and secured thereto
substantially throughout its extent, is detachably mounted
on the periphery of the drum. Such detachable mount
journalled in Ibearings mounted in opposite vertical side
plates of the housing 10. The projecting end of the shaft
21 is connected by suitable drive means to the electric
ing is highly desirable to permit rapid replacement of the
layer of cushioning material ‘when this layer is damaged, 25 motor 12. The circumferential shell 17 of the drum has
a narrow slot 22 extending across the drum at a small
as may occur in use. The provisions for this purpose
oblique
angle to the drum longitudinal axis. A pair of
comprise specially designed annular retaining chucks
sandpaper clamping trolls 23 and 24 are rotatably mounted
which engage beveled circular edges of the backing plate
in the end plates and arranged parallel and adjacent to the
sections and are held in the edge engaging position by
inner end of the slot 22, as shown in FIG. 5. The rolls _
30
locking means threaded on- the drum shaft and operable
have projecting squared ends at opposite ends of the drum
by the use of a special wrench. While the described ar
adapted to be engaged by suitable tools for simultaneously
rangement substantially reduces the time required to re
turning the rolls. The portion of each roll Within the drum
place the cushioning layer as compared to replacement of
is ?attened along one side 26 and the remaining circume
a cushioning layer permanently attached to-the drum
ferential portion knurled. The knurled roll portions
surface, the time required is still substantial.
cooperate to form a clamping means for the tapered ends
In accordancerwith the present invention, the rotary
of a sheet of abrasive material 28, such as sandpaper or
drum and cushioning element backing plate are con
emery cloth, sized to ?t around the drum and its ends to
structed to further reduce the time required to replace
be inserted into the narrow slot formed by the ?attened
the detachable cushioning element, by a simpli?ed and 40 roll portions. The rolls are then turned in opposite direc
more effective construction of the provisions for holding
tions by the operator so as to have the knurled roll por
the detachable cushioning element on the drum. In par
tions grip‘ the opposite ends of the abrasive sheet and draw
ticular the circumferential surface of the drum is made
it taut around the drum periphery. A stationary set screw
of a non-magnetic conductor material, e.g. aluminum,
30 on the drum abuts a pin 31 positioned in a circular
with magnetized metal incorporated at special locations 45 groove 29 in each roll to indicate the sheet receiving
therein for contact with the steel backing sheets of the
position of each roll.
cushioning element and of su?icient magnetic force
The detachable cushioning element consists of a rela
alone or in conjunction with the holding effect of the
tively thin backing sheet of magnetic material, prefer-_
provisions for holding the sandpaper sheet, to hold the
ably two substantially semi-cylindrical thin plates '38 of
detachable cushioning element ?rmly in position on the
spring steel, shaped to ?-t around the periphery of the
drum against the centrifugal and frictional forces present
drum with one pair of straight edges substantially in con
when the drum is rotated in use at its maximum operating
tact and oblique opposite edges extending along and regis
tering with the oblique edges of the drum slot 22 when
speed.
The various features of novelty which characterize this
mounted on the drum.
In assembling the cushioning element, the backing sheet
invention are pointed out with particularity in the claims 55
sections are positioned around a master drum and a layer
annexed to and forming a part of this speci?cation. For
of cushioning material 40, preferably a sheet of sponge
a better understanding of the invention, its operating ad
rubber, conforming in size and shape to the composite
vantages and speci?c objects attained by its use, reference
backing sheet, is bent around the sheet and vulcanized
should be had to the accompanying drawings and descrip
thereon
substantially throughout its extent. The two
tive matter in which I have illustrated and described a
part construction of the backing sheet facilitates the in
preferred embodiment of the invention.
stallation and removal of the cushioning element from the
Of the drawings:
drum without removing the drum from the machine.
FIG. 1 is a perspective view of one type of ?oor surfac
In accordance with the invention, a series of elongated
ing machine for which the invention is particularly 65 magnetized inserts 4-2, preferably of “Alnico,” an alloy of
adapted;
‘
iron, nickel, aluminum and cobalt, are incorporated in
FIG. 2 is a perspective view of the rotary drum show
the drum shell 17 at longitudinally spaced points along op
posite edges of the slot 22. The magnetized inserts may
ing the cushioning element about to be secured;
FIG. 3 is a longitudinal section through the drum;
FIG. 4 is an end view of the drum;
FIG. 5 is a fragmentary enlarged transverse section
through one end portion of the drum; and
be incorporated in the drum in any suitable manner, such
as by casting the magnetic alloy into elongated recesses
or openings in the shell ‘17 or placing permanent magnets
in such shell openings and peening the edges to secure the
3,039,241
3
4
magnets in position. The outer surface of the magnets 42
conforms to the surrounding area of the drum.
to attract and hold saidv backing sheet with its edge por
tions aligned with said slot.
The ‘cushioning layer 40 has its outer sheet-contacting
2. A rotary surfacing element for a floor surfacing ma
chine comprising a hollow rotary drum formed by a cylin
drical shell of non-magnetic material closed at its ends
surface formed with a series of closely spaced parallel
grooves 44 of rectangular cross-section, preferably 14;"
square and 1A" apart. This grooved construction of the
and having a slot extending lengthwise of the peripheral
cushioning layer aids in the dissipation of heat generated
during operation, and also aids in the traction effect on the
surface thereof and obliquely to the drum axis, means
with-in said drum arranged to receive and hold taut the
superposed sheet of abrasive material.
ends of a sheet of abrasive material adapted to ?t around
In the original assembly of the rotary surfacing ele 10 said drum, cushioning means for said sheet of abrasive ma
ment, the detachable cushioning element is opened to the
terial comprising a circular backing sheet of magnetic
dotted line position indicated in FIG. 6 and positioned
metal shaped to ?t around said cylindrical shell and a
around the shell 17 with its oblique edges aligned with the
continuous layer of resilient material coextensive with
corresponding edges of the shell slot. The backing sheet
and secured to the outer side of said backing sheet, said
closely contacts with the peripheral surface of the shell
backing sheet and layer of cushioning material having
and the magnets 42 are preferably so spaced and sized to
spaced oblique edge portions in line with said shell slot,
provide sufficient magnetic holding force to hold the cush
and magnetized meta-l incorporated in said shell adjacent
ioning element in that position against displacement under
to and along opposite sides of said slot and adapted to at
the maximum centrifugal elfect caused by the drum rota
tract and hold said backing sheet with its oblique edge
tion and the maximum friction effect in operation between
portions aligned with said slot.
the floor and abrasive sheet. The sheet of sandpaper or
other abrasive material is then wrapped around the drum
3. A rotary surfacing element for a floor surfacing
machine comprising a hollow rotary drum formed by
a cylindrical shell of non-magnetic material closed at its
ends and having a slot extending lengthwise of the pe
ripheral surface thereof and obliquely to the drum axis,
and cushioning layer and the opposite ends of the sheet
bent and inserted through the slot 22 and between the
sheet-holding rolls 2,3, 24. When the rolls are turned to
tighten the sheet around the drum, an additional cushion
means within said drum arranged to receive and hold taut
the ends of a sheet of abrasive material adapted to ?t
element is then ready for operation. When the cushion
around said drum, cushioning means for said sheet of
ing layer is damaged in operation the described operation
abrasive material comprising a circular backing sheet
is reversed and a new cushioning element of similar con 30 comprising a pair of semi-circular sections of magnetic
struction substituted or the damaged element repaired and
metal shaped to ?t around said cylindrical shell and a
replaced.
continuous layer of resilient material coextensive with
With the described construction, there is a considerable
and secured to the outer side of said backing sheet, said
saving in parts costs as compared to the drum construction
backing sheet and layer of cushioning material having
ing layer holding effect is provided. The rotary surfacing
of my said prior patent, the special holding chucks, hold
ing nut and operating wrench being eliminated. The
simpli?ed drum construction substantially reduces the
time required for mounting and replacing the cushioning
means, with a consequent increase in the production time
3 UK
spaced oblique edge portions in line with said shell slot,
and magnetized metal incorporated in said shell adjacent
to and at transversely spaced points along opposite sides
of said slot and adapted to attract and hold said backing
sheet with its oblique edge portions aligned with said slot.
of the operator.
4. A rotary surfacing element for a floor surfacing
40
While in accordance with the provisions of the statutes
machine comprising a hollow rotary drum formed by
I have illustrated and described herein the best form of
a cylindrical shell of non-magnetic material closed at its
the invention now known to me, those skilled in the art
ends and having a slot extending lengthwise of the pe
will understand that changes may be made in the form of
ripheral surface thereof, a sheet of abrasive material
the apparatus disclosed without departing from the spirit 45 adapted to ?t around said drum, cushioning means for
of the invention covered by my claims, and that certain
said sheet of abrasive material comprising a circular
features of my invention may sometimes be used to ad
backing sheet of magnetic metal shaped to ?t around said
vantage without a corresponding use of other features.
cylindrical shell and a continuous layer of resilient mate
What is claimed is:
rial coextensive with and secured to the outer side of said
1. A rotary surfacing element for a ?oor surfacing ma 50 backing sheet, said backing sheet and layer of cushioning
chine comprising a hollow rotary drum formed by a cy
material having spaced edge portions in line with said
lindrical shell of non-magnetic material closed at its ends
shell slot, magnetized metal incorporated in said shell
and having a slot extending lengthwise of the peripheral
and adapted to attract and hold said backing sheet with
surface thereof, means within said drum arranged to re
its edge portions aligned with said slot, and means within
ceive and hold taut the ends of a sheet of abrasive mate 55 said drum and independent of said magnetized metal ar
rial adapted to ?t around said drum, cushioning means
ranged to receive and hold taut the ends of said sheet of
for said sheet of abrasive material comprising a circular
abrasive material.
backing sheet of magnetic metal shaped to ?t around said
cylindrical shell and a continuous layer of resilient material
References Cited in the ?le of this patent
coextensive with and secured to the outer side of said back 60
UNITED STATES PATENTS
ing sheet, said backing sheet and layer of cushioning ma
terial having spaced edge portions in line with said shell
slot, and magnetized metal incorporated in said shell adja
cent to and along opposite sides of said slot and adapted‘
2,437,958
2,662,353
Holt _______________ .__. Mar. 16, 1948
Bergman et al. _______ __ Dec. 15, 1953
2,788,743
Schwerin ______..‘_..>._.T____v__7 Apr. 16, 1957
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