Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
38
This invention relates to endless Fo~r tran.~mlssion belts of the
type known as-"V~rib~ed", "nLltiple rib" or nLlti-ribbed".
V~ribbed belts havLng tran~verse slits or cuts in the ribs there-
of ha~e been proposed ~2reto~ore and ex~mples of such belts are shown in
u.S. Pa~ent No. 2,728,239. Howev~r, belts of the type shown in this E~tent,
when operated around so-called backside driv~ sheaves, are subjected t~ con-
siderable stresses, generally resulting in cracks emanating from the top
~f the slits or cuts to the top of the helt.
Further, belt~ o~ the type shcwn in U.S. Patent 2,728,239, where
notches are cut into the ribbed portion o the belt, while providing de-
sired ~1~ ~ ility, d3 not always pr~vide optimum support ~or their associ
ated load-carrying section.
A~cordin~ly, the ne~d exists of a simple and eoonomical V-ribbed
endless power transmission belt havlng high ~lexibility and large load-
carrying capaci~y, yet capable o~ operating over extended timer periods in
a stress-relieved and oool m~nner~
It is therefore an object of one broad asp0ct of the present in-
vention to provide an ~ ved V-ri ~ endle~s power transmission kelt.
AnDther object o another aspect o~ the pre~ent invention is to
provide a m~thvd for making an improv~d V-rihbed endless power tran.qmlssion
b~lt.
In accordance with a broad aspect of the present Lnventionl th~re
. .. .. . , . _ , .. .. . .. . . _ . . _ _ . . . . . .. .. ..
is provided an e~les~ ~ er tran~ml~sion belt made primarily of an elas-
tomeric material and oomp~isLng a tension ~ection, a load-carrying section
and a ri~bed oompres~ion seation havLng stres~-r~lief means in the ri~bed
portion of ~he co~pre3~ion~section. Mbre particularly, the belt of an
aspect of this lnv~ntion has a rikbed ~ection defined by a ~lurality of xibs,
the ribs being deflned by a plurality o~ alternatin~ projections and re-
cesses. The ribbed sestion ha~ stress-ralief mean~ oomprisiny a plurality
of folded f~bric poxtions ext2nding i~bo the ribs at spaced interval
.
,
L3~
the endless path of the belt. Each of the folded fabric portions
has associated portions of fabric in contact at an associated
interface which serve as stress-relief slits for the be~lts.
Additionally, the associated portions of Eabric serve as fabric
cushions on opposite sides of -the associated stress-relief slit.
By one variant, thereof, the stress-relief means extends
a distance of 0.3 and 0 95 times the thickness of the compression
section.
By another variant, the compression section is a
fiber~reinforced elastomeric layer.
By a variant~ the folded portions may be either equally
or unequally spaced alon~ the endless path.
~ By another variant~ the compression section has an
; elastomeric bottom layer and at least one additional layer ar-
ranged inwardly o* the bottom layer.
- By a variation thereof, the additional layer is a
fiber-reinforced elastomeric layer
By another aspect of this invention a method is pro-
vided for making an endless power transmission belt made pri-
marily of an elas-tomeric materiaI, the belt comprising a tension
section, a load-carrying section adjacent the tension section
and a ribbed compression section adjacent the load-carrying
; section defined by a plurality of ribs, -the ribbed section having
stress-relief means comprising a plurality of folded fabric
portions extending into the ribs at spaced intervals along the
endless pa-th of the belt, each o~ the folded portions having
associated portions of fabric in contact at an associated in-ter-
face, the interface serving as stress-relief slits for the belt,
and the associated portions of the fabric serving as fabric
- 3 ~
' ''` ~
- .
3~
cushions on opposite sides of an associated stress-relief slit,
the method comprises the steps of; (a~ fabricatin~ a vulcanized
belt sleeve defining the tension section, the load-carrying
section and the compression section; (b) providing -the compres-
. :
`
~ .
~ 3 a -
~ ~-J
'
3~
sion section with a plurality of folded portions each having
associated portions of fabric material arranged closely ad-
jacent each other, tc3 the folded portions to extend inwardly
into the compression section$ and (d) cutting the sleeve to de-
fine a plurality of longitudinal ribs in the compression section.
By one variant, step (g) of fabricating the sleeve
comprises the steps of; (i) wrapping at least' one layer of
-~ fabric around a cylindrical drum having a central longitudinal
axis; ~:~ii) wrapping a first layer of elastomeric cushion
material, a layer of load-carrying cord and a second layer of
elastomeric cushion material consecutively around the fabric~
wrapped drum; (iii) wrapping a folded portion assembly com
prising an elas-tomeric material having a plurali-ty of fabric-
lined grooves on the outer surface thereof around the second
elastomeric cushion layer; and (iv) vulcanizing the resulting
sleeve,
By another variant, the folded portion assembly is
formed by the steps of; (i) lining a member having a plurality
of alternating ridges and grooves with a fabric material to
-: 20 define fabric-lined ridges and grooves; (ii) placing a plurality
of elongated strips of elastomeric material in the fabric-lined
grooves; and (iii) lay;ng a sheet of elastomeric materîal over
the strips to define the assembly.
By one variation -thereof, the placing step (ii) com-
prises placing a plurality of elongated strips of elastomeric
material, which are free of reinforcing means, in the fabric-
lined grooves.
By another variation, the laying step. (iii) comprises:
laying a sheet of elastomeric material, the sheet being free of
_ 1~
. -
' ' ' ~ ~ ' . ' .
3i~3
reinforcing means, over ~:he strips.
By a further variation, the laying step comprises
laying a sheet of elastomeric material, the shee-t having re-
inforcing means dispersed there-through 7 over the strips.
In the aceompanying drawings,
Figure 1 is a perspective view illustrating one
exemplary embodiment o* the endless power transmission belt of
one aspect of this invention;
_ 4 a -
.
: . ' ' '
313
Figure ~ is a fragmentary cross-sectional vi~w taken at the line
2-2 of Figure l;
Figure~ 3, 4 and 5 illustrate a series of method steps which may
be employed to define the belt of Figure 1; and,
Fig~re 6 ie a fragm~n~ary cro~ ectional view illustratLng another
exemplary ~nbodiment of the kelt of another aspect of this invention.
Reference is ncw ~adc to Figures 1 and 2 o~ the drawing which
illustrate an Qxe~plary embodLment of an endless power transmission belt of
one aspect o~ this invention which is desi~nated generally by the reference
n~eral 2. The belt 2 is capable of carrying substantial loads, has opti-
mum flexihility, and is, in e~sen~e, a stress-xelieved multi-ribhed belt.
The belt 2 compri~e~ a ten~ion section which is designated gener-
ally by the reference numeral 4, a load-carrying ~e,ction 6, and a compres-
sion section 8,
The tension section 4 of ~he belt 2 comprise~ a top fabric c3ver
5 which is impregnated wi~h a ~uitable elas ~ ic compound. Alte~natively,
as shcwn in Figure 6, the ten~ion ~ection 4A can oomprise a suitable elas-
tcmeric ccmpound 7A which i~ adjoined on one side ther~of by the cover 5
and by the load-carryLng ~ection ~A o~ it~ opposite side.
R~fe~ring again to Figures 1 and ~, the load-carrying ~ection 6
- oo~yrises a helically~wound load-carrying cord 10 which is suitably embedded
in a known manner in an elaatomeric cuehion bas3 12. ~owever, it will ~e
appreciated that the load-carrying section 6 can be ~ade of any ~uitable
material a~d utilizlny an~ suitable technlque kncwn in the art.
The oompre~lDn ~ectio~ 8 comprises a ribbed section 14 defined by
a plurality of longit ~ ly ~xtending ribs each designated by the same
refer~nce numeral 16, and the rib~ 16 are de~ined by a plurality of alterna~-
ing projections 17 and reces~e~ 18. The oompression ~ection 8 has means for
-
-- S --
-
- : ~ . - - : :
~ . : . . .
8~3~3
stress-relief of the belt thereof around associat~d sheaves. l~e stress-
. relief ~eans is designated g~nerally by tha reference nu~.eral 20 and com~
p~ises a folded pvrtion of fabric ~xtending m to the oompression section at
spaced po~itions, which is this example of this aspect of the in~ention are
equally spaced along the endla85 path of the compression section and hence
along the enlless path of the belt. Alternatively, the stress-relief means
can be staggered~
Each of th~ ~olded portion~ 20 ha~ associated portions 22 of fab-
ric in contact at an associated interface 24 hereby the i~terfaces 24 deflned
~0 by associated portions 22 serve, in essence, as s~ress-relief slits ~or the
belt 2~ FuIther, the assccia~ed portion~ 22 serve as fabric cu~hions on
opposite sides of an associated s~xe~s-relief slit as defined by the
as~ociated in~exface 24.
As the belt 2 travels around associated ~heaves or pulleys, the
belt tends to compre~s the compres3ion sectlon 8 in the usual manner while
stretching the ten~ion section 4 of ~he belt. The compression of the comr
pression section 8 is easily accDmDdated by the cushio m ng action provided
by the foldel portions 22 of the fabric which also define the interfaces
24 and serve a~ ~tress~-relief ~lits whereby the belt 2 is flexed in an easier
manner with minimum Lnternal ~tres~e~, thus pro~iding nU~LUmUm hysteresis,
thereb~ enabling the belt 2 ~o run in a cooler mannar.
m e load-carrying section 6 of the belt 2 i~ provided with opki
mum support by the portions 22 in face-to-face contact at interfaces 24 and
the ~lastomeric m~terial comprisLng ~he layer 14. Additionally, the belt 2
has high fl~xibili~y without rsquir mg the provision of teeth or cut notches
in the co~pros~ion section. O~viously~ ~he ~rovision of teeth or notches
in the compre~ion ~ection a~ a~hieved in previously proposed kelts, results
in a reduced amDunt of support of the load-carrying section of such
previously prcposed belt~.
- 6 -
- :
: The balt 2 can be made utilizing any suitable technique or method
kncwn in ~he art; hcwever, the belt 2 is preferably m~de utilizing the
method steps described her~inafter and as shown in Figures 3~ 4 an~ 5 of the
draw mg wher~by a belt sl~ave is first defined and a pl~rality of belts 2
i~ cut from ~uch sleeva.
m e method of an aspect of this invention ccmprises the steps of
lining a member 26, as shGwn in Figure 3, ~hich has a plurality of alter-
nating ridges 28 and groove~ 30, such a~, for example, a metal forming m~m~
ber, with a fabric m~terial which i~ designa~ed by the ref~rence numexal ~2
to define fabric-lined rid~es and groove~. A plurality of elongated strips
34 of elasbomeric ma~erial are then placed in the fabric lined grGove~ and
a ~heet ~6 (ihown having an exaggerated thickness) of elastcmeric material
is pla~ed or laid over the ~trip~ to define an assembly which is d~signated
generally by the refarence numeral 38.
The ~elt 91eeve~ designated generally by the reference numeral 40
is built up in inverted ~agbion on a aylindrical dn~n 42 as shown in Figure
4. m e drum 42 ha~ a right circular cylindrical outside ~urface 44 and is
a oonventional drun used to build up, cure and cool a kelt sleeve 40. m e
belt Rleeve 40 is buil~ ~ by wrappLng consecutively, one or m~re layer~ of
fabric 46, a layex o elasbomeric cu3hion ~aterial 48, a layer of helically-
w~ ~ load-carryl~g cord 50, and a layer o~ e~asto~eric cushion material 48.
The assembly 38 i~ re~oved or suitakly lifted awa~ from th~ m~er 26 and
such assembly i9 wrapped around the out~ide cushion layer 48 with the fabric
layer 32 to the outside, ~hereby oompleting the uncured sleeve. me uncured
belt sleeve 40 is ~rappad or otherwise .unwardly compressively ancircled and
thereaf~er cured in the ~ual known manner. The curing action causes the
strip3 34 and 3heet 36 to flcw toge ~ a~ a unitary ~ass which when the
individual belts 2 are out ~rom such sleeve define layer 14 of the com~res-
sion section. The cured sle~e 40 is then oDol~d utilizing techniques ~hich
7 ~
.- . - - . . . : ~. .
: - : ,
'. : . .. ' ' :
are kncwn in the art.
me ribs 16 are ~hen defined in the cured sleeve 40 by die cutting
or by grinding, as sh~wn in Figure 5. The drwm 42 is supportel ~y rotation
on suitable support ~eans, not shawn, and a suitable cutting means sh~wn as
a rotary wheel 52 having a grinding face o~ suitable cro~s-section is emr
ployed to precisely define the ribs. m e grinding ~heel 52 is rotated while
rota~in~ the slee~e 40. As the sleeve 40 is ground to define the ribs 16,
the fabric 32 is remDve~, except in the folded portions 22. The belts 2
are -then cut from sleeve 40 in kncw~ m~nner.
Another exemplary embodiment of the belt of another aspec-t of this
invention is shown in Figure 6. The belt illustrated in ~iyure 6 is simi-
lar bo the belt 2; therefore, such belt is designated by the re~erence numr
eral 2A and representative part~ of each belt similar to corresp~ndin~ parts
of belt 2 are designated by the same reference numeral as in belt 2 followed
by an assc~iated letter designaticn A and will not be described in detail.
Only those oamponent parts o~ belt 2A which are different from corresponding
parts of belt 2 will be d~signated ~y ~ew reference numerals.
The difference bet~een the belt 2A of Figure 6 and the belt 2 are
that the tension section 4A instead of having a single ~abric layer ~A has
a layer 7A of ela~tomeric material k~ween the load-carryin~ section 6~ and
the top fabric layer 5A; and that the compression section ~ has a platform
l~yer 54 o~ elastomeLi¢ ~aterial between the load-carrying ~ection 6A and
ths ribbed section 14A.
In this di3closuxe of aspects of this inv~ntion each of the belts
is shcwn by cro59 hatching as beiny an ela~tomeric material in the form of
rubber. Hcwever, it will be appreciated that each belt may be made of one
or mDre sultable ~la~tom~ria material~ including natural and synthetic rub-
ber and other synthetic plastic m~terials. Additionally one or ~Dre layers
of such ~ can have reinforcin~ means, such as, for example, fibers
- 7 a -
,: ' ' . .:
,.
.
, '
thereby ~efining an elastomeric rubber matrix loaded with fibers. ~or
example, the ribked section 14 o~ the belt 2 shc~ in Figure 1 can be a
suitable ala~tcmeric xubber oompound having up to about 40 parts of ~ibers
56 dispersed therethrough. These fibers 56 can be any ~uitable material
known in the art, and may be of any sultable diameter and length and arranged
in any desired pattern relativs ~o the longitudinal axis of the belt as~soci
ated therewith to ~ t the de~ired characteristics to ~uch belt. l~e
plat~onm layer 54 of the kelt 2A ~hown in .Figure 6 also comprises the ~ibers
56A.
In this disclosure reference is made to the fabric layers 5 and
5A, and to fabric material 32 and fabric portions 22. Each o~ such layers,
material and p~rtions m~y be ~D~2n fahric, n~n-woven fabric, or knit~ed
fabric, as desired.
The folded porticns 20 can extend into the compression section 8
a dis~ance equal to about 0.3 to about O.9S ti~es the thicknes~ of the comr
pre~sion ~ection 8 of the finish2d bYlt. ~y proper selection of the member
26 shown in Figure 3 and d~pth of cutting ox grinding the ribs 16 and re-
ces es 18, a~ sh~wn in Figuro 5, the finished belt can have transversely
connected asso~iated ~abric portion~ 22
- 8 -
- .
... ~ . . . .
