Note: Descriptions are shown in the official language in which they were submitted.
This lnvention relates to improvement in the
mounting of sanding bel-ts for rotation and, more particu-
larly to an improved drum for coupling a sanding belt to a
drive motor, such as a hand-hel~ drill.
Rotary drums for sanding belts have been used in
the pa~t but, Eor the most part, they are made up of several
parts and require assembly which adds to production costs.
Also, a major drawback of drums previously made for this
purpose is the relatively short operating life, requiring
replacement and adding to the overall cost of sanding
operations. Because of these drawbacks, a need has arisen
for an improved drum for sanding belts wherein the drum is
of simple and rugged construction, has a long operating
life, and can be produced at minimal cost.
The present invention satisfies the aforesaid
need by providing a drum of a one-piece construction. The
clrum is formed from a moldable, resilient material which has
a long useful operating life and does not need replacement
except at relatively infrequent intervals.
To this end, the drum comprises a central, imper-
forate web integral with a pair of outer peripheral flanges
provided with a cylindrical outer surface. The drum is
formed from a resilient material, such as natural rubber, so
that, when the drum is rotated at a high speed, the web will
expand or stretch radially outwardly and the flanges will
- flex radially outwardly under centrifugal force. This will
cause the web
. .
.~ :
-2-
.
~ 25~
I and flange to press firmly against the inner surface o a
2 ~anding belt on the drum to enhance the frictional engagement
3 ~ therebetween Thi5 feature assur~s tha~ ~he sanding belt
41 will not move circumferentially of the ~lange or axially of
5~ the drum it~elf when ~he drum and belt are rota~ed.
61 One embodiment of the drum uses a pair of annular
7 ribs at the outer side extremities of respective 1ange~.
8 A sanding belt having a pair of axially spaced, inner peripheral
9 shoulders on the inner surface of the belt is u~ed with this
IO type o drum so that the ribs engage the shoulders when the
11 belt is on the drum to prevent axial movement of the belt on
12 the drum. A ~econd embodiment of ~he drum ha~ a cylindrical
13 outer surEace for the flanges with the surface being free of
the ribs of the ir~t embodiment. In thi3 case, the drum i~
used wlth a sanding belt which ~y have abrasive on its
16 inner surface as well as its out:er surfaces. If the abrasive
17 is used on the inner surface, it: frictionally engages the
18 cylindrical outer ~urface of the web and 1anges to ~ncrease
19 the friction engagement therebet:ween. However, the abrasi~e
i~ not needed on the inner surface for this purpose.
?l The primary ob;ect of this invention is ~o provide
22 an improved drum for a sanding belt wherein the drum is of
23 a moldable material, is of a s~mple and rugged one-piece
24 construction, and can be made at mlnimal C08t yet the drum
25 has superior holding power to re~ain a Yanding belt thereon
26 even when operating at high rotational speeds.
27 Another ob~ect of this invention is to provlde a
28 drum of the type described wherein the drum is formed from a
29 re~ilient ~atcr~al and has a central, expandable web integral
30 with a pair of outer peripheral ~lexible flanges provided
3l , with a cylirlrlcal outer urface, whereby the web will
i
expand and the flanges will flex radially outwardly due to
centrifugal force to frictionally engage the inner surface
of a sanding belt to thereby substantially eliminate
circumferential and axial movement of the belt on the drum.
S Other objects of this invention will become
apparent as the following specification progresses, re-
ferences being had to the accompanying drawing for an
illustration of the invention.
I IN T~E DRAI~ING:
2 Fig. 1 i~ a perspective view of one embodiment of
3 ¦ the sanding drum of the present invention;
4 Fig. 2 is a vertical section through the drum and
illus~Fating the way in which i~ is moun~ed on ~he chuck of
a hand drill;
7 Fig. 3 is an enlarged fragmentary, cro~s sPctlonal
vlew of the drum, showing a ~econd embodiment of the drum
9 fos use wi~h a sanding belt having abrasi~e on both the
inner and outer ~urfaces thereo;
11 Fig. 4 i~ a view of the sanding bel~ used with the
12 drum of Fig. 3;
13 Fig, 5 is a view similar to Fig. 3 but showing the
14 drum of Figs. 1 and 2; and
Fig. 6 1~ a view similar to Fig. 4 but showing a
1~ sanding belt of the type used with the drum of Figs. 1, 2
17 and S.
18 A first embodiment of the sanding belt drum of
I9 th~s invention i~ broadly denoted by the numeral 10 and i5
shown in Figs. 1, 2 and 5. Drum 10 is formed from ~ resilient
21 ~aterial and compr~se~ a circular, flexible, imperforate
22 central web 12 and a pair of ~lexible outer peripheral
23 flanges 14 integral with web 12 so that drum 10 is of a one-
24 piece construction. The web and ~langes are preferably
formed simultaneou~ly in a molding process. The web is of a
26 thin wall eon~truction and, a shown ln Fig~, 2 and 5, i~
27 provided with a pair of bosses 16 at t~e center thereof for
28 support purpo~e~. The bos~es pro~ect laterally from opposite
29 sides of the web. ~hile Fig. 5 ~how~ ~he sides of the web
parallel with each other, they could be tapered from the
31 ~enter outwardly with the thlnne~t part near the outer
32 periphery the web to provide additional ~upport.
~ .
A pin 18 extends through the boss and the web as
shown in Figure 2. Thus, a chuck 20 on a hand drill or the
like can grip the pin for rotating drum 10 about the
central axis of web 12.
Flanges 14 have cylindrical outer surfaces and
project laterally in opposed directions from the outer
periphery of web 12 as shown in Figures 2 and 5. The
flanges have respective integral ribs 22 at their outer
extremities. These ribs are formed with the flanges in a
moldir.g process. The flanges have a thin wall construction
and, because they are resilient, they are essentially
flexible so as to flex radially outwardly when subjected
to centriugal force. Similarly, web 12, being of a thin
wall construction, and formed from a resilient material can - ;
; 15 expand or stretch radially outwardly under centrifugal
force as drum 10 is rotated at high speed, such as 2200
rpm or the like. This assures a positive frictional
engagement between the web and the flanges and the inner
surface of a sanding belt mounted on the drum for rotation.
For additional holding capabilities, ribs 22 are
provided for use with a sanding belt 24 (Figure 6) which -~
comprises a band 26 provided with annular shoulders 28 on
the inner surface thereof at locations spaced inwardly from
the opposed sides thereof. These shoulders can be formed
by securing a band to the inner surface of band 26 with the
inner band having an axial length less than that of band 26.
- Shoulders 28 abut ribs 22 in the manner shown in
:
--6--
Figure 5 when band 26 is mounted on flange 14. Thus, a
tendency for -the belt to move axially of the drum is coun-
tered in two ways, first by the frictional engagement be-
tween the flange and the inner surface of band 26 and,
secondly, by -the stop feature provided by the engagement
of ribs 22 with shoulders 28.
Drum 10 has the following typical dimensions:
Maximum diameter of about 3.80 inches, web thickness of
about .25 inch, total axial length of flanges 14 of about
1.40 inches, and angle a (Figure 5) of about 5. The
material of drum 10 is typically 55 Durometer natural rubber
but can have a hardness in the range of 45-65 Durometer.
In use, pin 18 is secured in the conventional
manner to chuck 20 and sanding belt 24 is then placed on the
drum and seated on the flanges 14 in the manner shown in
Figure 5. Then the hand drill associated with chuck 20 is
actuated to rotate drum 10 and thereby permit the sanding
of a surface by the outer surface of band 26 which is pro-
vided with an abrasive in the usual manner. During the
sanding operation, web 12 will expand radially outwardly
and flanges 14 will flex outwardly yet web 12 will generally
maintain its disc-like shape since it is rotating in its own
plane. There will be no circumferential movement of band
26 relative to flanges 14 during rotation of drum 10 because
of tha frictional engagement of web 12 and flanges I4 and
the inner surface of band 26. Moreover, this frictional
engagement plus the stop action afforded by ribs 22 will
prevent any substantial axial movement of band 26 relative
to flanges 14.
--7--
1~ 112a5
I Fig. 3 L11u:trates snother embodiment of drum 10,
2 namely drum lOa. This drum ls subs~antially the same in all
3 ~ respects as drum lO except that drum lOa has no ribs 22,
41 Instead, dr~m lOa has a completely cylindrical outer surface
and is adapted for use wl~h a sanding band 24a which may
6 have abrasive on both i~s inner and outer surfaces. AbraRive
7 need not be on the inner surface and, if used, i~ need not
8 cover the en~ire inner surface as shown in Flg. 4, If used,
9 however, ~he abrasive on the inner surface provides greater
frictlon between the drum lO and the sanding belt. Without
Il the abrasive on the inner surace, there will be suf~icient
12 friction between the ~lange of drum lOa and the inner surface
13 o sanding belt 24a because of the expan~ion or stretching
14 of the central web of dru~ lOa and th~. flexing of outer
peripheral flanges due to centrif.ugal force, thereby cau~ing
16 the web and flanges ~o be pressecl with greater force against ,
17 the inner surface of the sanding belt to achieve an increased
18 frictional force.
19 Although the foregoing invention has been described
20 in some detail by way of illustration and example for purposes .
21 of clarity of understanding, it wlll be obvious ~ha~ certain
22 changes and modifications may be practlced within the scope
Z5 of the app Ided claims.
27
29 .
31
32 8.
