Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
7S49~
BACKG~OUND OF T~ INVENTIO~I
Thls invention rela~es to an improved, ad~ustable,
force-sensing mounting device.
When equipment such as machines, lathes, drill
presses and o~her types of production appara~us are installed
in industrial plants, it is important that they be leveled for
firm support on the plant floor and that the load be distri-
buted equally so as to avoid misalignmen~ and the internal
stress caused thereby. It is customary to provide leveling
screws or similar adjusting means on the legs or supports on
which machinery is mounted so that each leg or supp~rt can
be ad~usted as necessary to compensate for the irregularities
which are found in most factory fl~ors.
In addition to precise leveling of such eauipment,
it is usually desirable to compensate for the vibration which
occurs during operation by interpo~ing some vibration-
absorbing material, such as syntheti~ rubber, between the
factory floor and the equipment
In recent years, industrial mounting devices have
been developed which serve the dual purpose of permitting
hei8ht adjustment and dampening vibration. These so-called
adjustable vibration isolators are availabl~ in various forms,
one of the most widely adopted being shown in my U.S. Patent
No. 3,332,647, granted July 25, 1967.
In order to obtain the ma~imum benefit from mounting
industrial equipment on ad~ustable vibration isolators, it is
necessary not only to level the equipment, but also to equalize
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~L~75494
the load supported by each such isolator. ~ithout such
- equalization, a unit of equiprnent mounted on four or more
legs may be subjectcd to detrimental bending or twisting
forces. S~lch misalignmont causes internal stresses
within thc machine structure and this is frequently
responsible for excessive wear and tear and vibration.
The adjustable load-sensing vibrator isolator shown
and described in my co-pending Canadian Patent Application
Serial No. 269,971, filed January 18, 1977, was conceived
and developed to provide means for constant accurate
read-out of load forces exerted thereon.
It is a pricipal purpose of the present invention
to provide leveling means with superior load-sensing
accuracy, which may be combined with variouS forms of
mounting devices either with or without vibration
isolating features.
It is another principal object of my invention to
supply a load-sensing device that is sufficiently
versatile to be incorporated in tie-down bolts and
similar means used to fasten machinery to factory floors.
It is a further object of my invention to provide
a system of adjustable, load-sensing mounts for supporting
a unit of industrial equipment which includes read-out
means electrically connected to said mounts, said read-out
means serving to provide continuous data as to the loads
exerted on individual mounts as well as the cumulative
total of such loads, thus enabling quick determination
of the center oi gravity of the equipment, the dynamic
forces transmitted to the floor on which the equipment
is supported and other load and force factors affecting
the operation, efficiency and stability of the equipment.
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It is a still furthcr objcct of my invention to
design a threaded, load-scnsing device embodying my
invention which can be substituted for thc levelinq screw
in the isolators shown in my Patent No. 3,332,~,~7 in
order to .~dd load-scnsing capability to such isolators.
It is an additional purpose of this invention to
accomplish the forcgoing object5 as wcll as those statcd
in my co-pending Canadian Patent Application Serial No.
269,971 at low cost and with maximum depondability and
10 versatility.
SUMMARY OF TilE INVENTION
This invention relates to adjustable, load-sensing
devices adapted to be used in mounts for industrial
equipment, and relates more particularly to systems of
such devices combined electrically with read--out means
to indicate dynamic forces exerted individually on such
devices and cumulatively on a plurality of such devices
; comprising a system.
My preferred means for measuring such forces utilizes
20 a shaft-like member having a threaded portion which is
adjustably engaged with a mounting device, the shaft
having a shank portion to which four strain gauges are
adhered in circumferentiaily spaced relation, the strain
gauges being connected in a Wheatstone bridge circuit
to a voltage source and to an amplifier which supplies a
~ variable electrical signal to a read-out meter, calibrated
- in appropriate force units such as pounds or kilograms.
A plurality of.such shaft-like members are used in
cooperating relation with a corresponding nurmber of mounting
30 devices in order to support a unit of industrial equipment.
The weight of the equipment is distributed among the mounting
devices, through which load force is exerted upon the
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rospecti-/o cylindrical mombers. Tlle shank portion of
each shaft-like member i9 sligiltly deformc~d in proE~ortion
to the load it suE~ports, and in proportion thereto. The
deformation of tho shank causes corresponding charlcJes in
the strain yauqes adherod to the surfaco thereof, and
thoso changes alter the elcctrical rosistances of the
strain gauges. Thus, when a voltage is applied to tho
strain gauges, the current which passes through tho Wileat-
stone bridge circuit is caused to vary in accordance
with changes in those resistances. The olectrical current
or signal is amplified and is measured by a meter, oscillo-
Scope or other suitably calibrated read-out device.
It is contemplated that there wili be three or more
load-sensing mounts to support a unit of equipment and the
load signal from each mount will be indicated on an
individual meter. In the more sophisticated versions of
this invention, there is a master meter in addition to
the individual meters and the separate signals from the
respective individual meters are integrated in the master
meter to show the total weight of the unit of equipment
supported on the individual mounts.
When four or more adjustable mounts as described
herein are used to support a single unit of equipment, the
proportion of weight supported by each such mount may be
equalized by selectively adjusting individual mounts until
the optimum distribution of load is achieved. This is
determined by observation of the output signal on each
meter.
During operation of the equipment, the variations of
force transmitted from the machine to the foundation may
be observed on the read-out device for each support. In
many cases, it is important that the upward dynamic force
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never exceed the static support forcel and thls may be observed
visually by watching the meters If desiredJ a warning signal,
such as a light, a bell, or a shut off switch may be actuated so
as to warn the operator or shut off the machine when the dynami.c
forces approach a pre-determined unsafe level or when the
rela-tionship between dynamic and static forces reaches the max-
imum safe level.
According to the present invention, an improved,adjust-
able, load and force transferring component i6 interposable in a
machi.nery mount between a bearing mem~er supported on a compress-
ible, resilient base and a machinery supporting member wherein
the component comprises a substantially cylindrical metallic
body having integral first, second, third and fourth portions
and wherein the first portion is adjacent one end of the body and
engageable by suitable means for precisely controlled axial
rotation of the body in alternate directions; the second portion
comprises a protrusion at the opposite end of the body adapted ~
to be supported in bearing relation on a planar portion of the ;`
: bearing member; the third portion extends from adjacent the first
- 20 portion toward the second portion and is externally threaded for
axially rotatable engagement in a cooperating internally threaded .
opening in the supporting member; the fourth portion comprises a
shank interposed between the second and thi.rd portions and has
a precision-machined peripheral surface, the fourth portion being
minutely and uniformly deformable when subjected to axial forces
exerted upon the body between the second and third portions;
. a strain gauge secured to the peripheral surface of the fourth
portion; a substantially axial passage within the body, substant-
i ially coextensive with the third portion.
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a first openlng extending substantially radiallv f~om the passaye
to the exterior of the body adjacent the fourth portion; a second
opening extending from the passage to the exterior of the body
adjacent the first portion; and a plural~ty of lead wires elect~
rically connected to the strain gauge and extending therefrom
through the first opening and the passage to the second opening
for connection to a source of electrical current and to suitably
calibrated read-out means,
BRIEF DESC~IPTION~OF ~E pR~WINGS
The preferred and alternative embodiments of my
inyention are shown in the accompanying drawing in which
Fig. 1 is a perspective view of a machine having
four legs, each of which is supported on an adjustable
load-sensing mount embodying my invention;
- Fig. 2 is a sectional view of the line 2 -- 2 of
Fig. l;
Fig~ 3 is a somewhat enlarged view of the reverse
side
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1~75494 -)
o~ the shank portion of the support member shown in Fig. 2;
Fig. 4 is a sectional view on the line 4 -- 4 of Fig.
3;
Fig. 5 is a diagram showing schematically a system of
S four load-sensing electrical circuits with individual and master
xead-out meters.
Fig. 6 is a sectional view of a modified form of adjust-
able machinery mount embodying my load-sensing invention; and
Fig. 7 is a sectional view of another modified form of
13 my invention comprisinga tie-down bolt and cooperating support
means, each having force responsi~Je means for sensing tensile
and compressive forces, respectively.
DESCRIPTIOM OF PREFERRED EMBODIMENT
Referring now to Fig. 1, an industrial machine, repre-
sented by dotted lines, is designated generally by the reference
numeral 10. The machine 10 has depending leg-s 12 at each of the
; respective four corners of the machine, each leg 12 having a
foot 14 at the lower end thereof and extending outwardly at right
angles thereto.
~ach foot 14 is supported on an adjustable vibration
~ 3 33~,~7
; ~ isolator 16 of the type disclosed in my Patent No. S~9d2~t~
Each such isolator 16 includes a circular base 18 of resilient
material such as Neoprene, a bearing plate 20 supported on the
top side of said base 18 and a circular cover 22 with a down- ,
wardly depending circumferential skirt as ~hown. The cover 22
i~ ad~ustably spaceable from said bearing plate 20 by means of
a threaded spacer 24 which is provided with load-sensing means
as hereinafter described. It is contemplated that the spacer 24
may be substituted for the adjustable leveling bolt shown and
30 ~ ~ described in Patent No. 3,332,64~.
-; ~n the illustrated embodiment, the cover 22 is pro-
vlded with a plurality of integral, downwardly depending ~ingers
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26 -- preferably three in number, spaced 120 degrees apart -- as
shown in Fig. 2. The resilient base 18 i9 provided with sockets
28 which are disposed at locations corresponding to the locations
of the fingers 26 and of sufficiently greater diameter to allow
free telescopic axial movement o~ the fingers 26 into and out of
said sock~s 28. Surrounding the top of each socket 28 is an
lntegral, upstanding flexible gripper 30 with an inwardly doubled-
back portion 32 of reduced lateral dimension adapted to grip the
lower end of the corresponding finger 26. The grippers 30 serve
to prevent lateral or rotary displacement of the cover 22 in
relation to the base 18 and also tend to resist inadvertent re-
moval of the cover from the base and bearing plate combination.
The shaft-like adjustable spacer 24, of high grade,
machinable tempered steel, has a hexagonal head 36 at one end,
a bearing portion 38 at the other end, and a threaded portion 34
interposed therebetween. Between the threaded portion 34 and
the bearing portion 38 the spacer 24 is provided wi~h a shank
40 of reduced diameter.
The cover ~ is provided with an axially disposed, in
ternally threaded hole 42 which is adapted to be aligned with an
opening 44 in foot 14, said opening 44 being of greater lateral
dimension than the diameter of the spacer 24. A lock nut 46 is
threadably engaged with the spacer 24, near the nead thereof,
and the spacer is then inserted through the opening 44 in the
foot 14 and engaged with the cover ~ in the hole 42 with the
shank 40 and bearing portion 38 projecting downwardly as shown
in Fig. 2 or engagement with the bearing plate 20. The spacer
24 may, of course, be rotated as necessary to adjust the spacing
between the cover ~ and the bearing plate 20 and, when the
desired spacing is obtained, the lock nut 46 is tightened against
the top o~ the foot 14 to prevent rotation of the spacer 24.
In my preferred e0bodiment, the load-sensing means
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compriseq four strain gauges 48a, 48b, 48c and 4~d adhered in
equally spaced relation around the shank 40. Said strain gauge~
connectcd together into a typical Wheatstone Bridge cixcuit.
A ~oltage from an electrical source 58 is applied to the bridge
in the normal fashion, with strain gauges 48a and 48c forming
one arm af the bridge and strain gauges 48b and 48d forming the
other arm of the bridge, as shown schematically in Fig. 5. The
bridge circuit is connected by wire 50 to amplifier 52 and meter
54. The electrical source 58 may be a battery or, if desired,
the circuitry may be modified to use the line current available
in the plant. ~,As shown in Fig. 3, each strain gauge 48 consists of
a continuous length of fine resistance wire 56 arranged in a
succession of back and ~orth linear rows in closely-spaced
parallel relation and bonded with suitable adhesive to the sur-
~ace of the shank 40. Strain gauges 48a and 48c are oriented
longitudinally with respect to the axis of the spacer 24, with
their centers 180 degrees apart. Strain gauges 48b and 48d
are oriented laterally or circumferentially with respect to the ~ ~;
spacer axis.
When no force is applied to the spacer 2g, the bridge
circuit is in balance and no signal passes therefrom to the
ampli ier 52 and the meter 54. When a compressive axial ~orce
~s exerted upon the spacer 24, the longitudinal dimension of
the shank 40 is slightly reduced in proportion to the force
exerted and the circumferential dimension i5 caused to increase
slightly in accordance with Poisson's law.
As the longitudinal dimension of shank 40 is decreased,
the length o~ the longitudinally aligned resistance wires 56
comprising strain gauges 48a and 48c, adhering to said shank 40,
is reduced accordingly. At the same time, the circumferential
dimension o~ the shank 40 increases, the length of the laterally
al~gned resi~tance wires 56 co~prising the strain gauges 48b
and 48d is stretched.
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A~ the resistance wires 56 comprising strain gauges 48a
and 4ac are shortened by reason of the axial compression of
spacer 24, the electrical resistance of those strain gauges is
decreased accordingly. As the resistance wires 56 comprising
strain gauges 48b and 48d are stretchad by reason of the increase
in the ci~cumferential dimension of the shank 40, caused by axial
compression on the spacer 24, the electrical resistance of those
strain gauges is increased accordingly. The decrease in the re-
sistance oE strain gauges 48a and 48c and the increase in the
resistance of strain gauges 48b and 48d unbalances the bridge
circuit and causes a current to flow, thus generating an electri-
cal signal which is communicated by the wires 50, to the amplifier
52 and the meter 54. The signal is substantially proportional
to the force exerted upon the spacer 24, and the meter 54 is cal- `
ibrated in units of force so as to give a direct read-out cor-
responding to the load force applied to the spacer 24.
Preferably, the spacer 24 has a central bore 49 which
extends axially from the head 36 and is substantially co-extensive
with the threaded cylindrical body 34 with an oblique hole 51 at
the lower end communicating with the shank 40. The wires 50 pass
through the oblique hole 51 and the axial bore 49 and out through
a hole in the fitting 60 axially engaged in an internally-threaded
opening 61 in the l.ead 36.
In the embodiment shown in Fig. 1, where the machine
10 is supported on four legs 12, each mounted on an isolator 16
- 25 which has lo~ad-sensing means, there would be a separate meter 54
,
to receive the signal from each o~ the respective isolators 16.
The s$gnals passing through the meters 54 can also be consolidated
~n a se~ies circuit to a master meter 62 which shows the total
load on the four isolators 16.
When a machine 10 is thus mounted on four adjustable,
load-sensing isolators 16, and the load readings are noted with
respect to each isolator, it can b~ a~certained at once from such
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readings whether the weight of the machine 10 i5 euqally distri-
buted. Wherc unequal load readings are obtained, the lock nuts
46 on the isolators 16 would be loosened and ~he spacers would
be turned one way or the other to raise or lower the respective
legs 12 to obtain optimum weight distribution.
~he amplifiers 52, the individual meters 54 and the
l~k G~
pe~ master meter,6~ would normally be contained in a housing 66, as
illustrated in Fig. 1 and indicated by dotted lines in Fig. 5.
The housing 66 would be located conveniently nearby such as on
an adjacent wall or on the machine itself. Alternatively, it
could be supported on a pedestal 68 near the machine 10 as shown
in Fig. 1.
A second embodiment of my ad~ustable, load-sensing
mount is 5hOWll in Fig. 6, wherein the leg of a machine ~not
shown) has an L-shaped foot 70 with an opening 72 through which
lS a threaded spacer 74 is adapted to extend. The spacer 74 has
an integral hexagonal projection 76 at the top which gripped by
a suitable wrench for turning the spacer 74 one way o~ the other.
At its opposite end, the spacer 74 has cylindrical
;~ shank i~ of reduced diameter with an integral bearing projection
78 extending therebeyond. As in the case of the shank 40 shown
in Figs. 2, 3 and 4, the shank ~ is provided with four spaced-
apart strain gauges 80, adhered to the shank ~ and oriented
- alternately in the same manner as the strain gauges 48a - d.
The spacer 74 is threadably engaged in a support mem-
ber 82 upon ~hich the foot 70 is supported~ A lock nut 84 may
be engaged on the threaded body of the spacer 74 protruding beyond
- the opening 72 and tightened against the foot 70 to secure the
~pacer 74 against rotational displacement such as might other-
wise be caused by the vibration or operating dynamics of the sup-
po~ted machine.
The bearing projection 78 ~f the spacer 74 is adapted
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1~75~94
to bea~ against and be supported upon a bearing plate 86. The
bearing plate may be part of an isolator having a resilient base
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indicat~d by the ref~rence numeralj~. The strain gauges 80
are part of a Wheatstone bridge circuit, as previously described,
and similarly the signals therefrom would serve to supply load
data to appropriate meters.
In the Fig. 6 embodiment, the resilient base or floor
is not an essential part of the combination as it is contemplated
that tha adjustable load-sensing means may have utility in cer-
tain circumstances where vibration or operating dynamics are
not such as to require isolation, but where load equalization is
important for machine stability or to avoid the misalignment in
the machine structure.
A third embodiment is shown in Fig. 7 where the adjust-
able, load-sensing means of my invention is shown in combination
with a tie-down bolt, of the type used in bolting machines to the
foundations on which they are supported.
Where the structure of the machinery is such as to re-
quire bolting directly to a special foundation or to the factory
floor, it is customary to set such tie-down bolts in the concrete
foundation or floor at selected locations corresponding to the
spacing of mounting points on the base or frame of the machine.
F~g. 7 shows a portion of a concrete foundation 90
and an elongated tie-down bolt 92 with the head 94 embedded in
said Goncrète foundation and the stem 96 projecting upwardly
beyond the foundation surface. A fragmentary portion of the
base or frame of a unit of equipment is designated by the ref-
erence numeral 98. At each of a plurality of selected locations,
said base 9~ is provided with an opening 100 which permits access
to a planar structural portion 102 having an internally threaded
mounting hole 104 adapted to st~raddle the tie-down bolt 92 in
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coaxial relation, leaving an annular space of uniform dimension
between-the bolt 92.and the hole 104.
An externally-threaded, hollow-cored spacer 106 is
cngaged in the hole 104, the hollow-cored portion be;.ng of suf-
: ficient diameter to enclose but not engage the stem 96 of the
bolt 92. Thë upper end of the stem 96 protrudes beyond the
spacer 106 and is threaded to receive a nut 108 which may be
tightened against a washer 110 to exert downward pressure on
the top of the spacer 106. A lock nut 112 is engaged on the ex-
ternally threaded portion of the spacer over the planar structural
portion 102 to prevent rotation of the spacer 106 in the mounting
hole 104.
At its lower end, the spacer 106 has a shank 114 of re-
duced diameter between its threaded portion and a bearing sup-
port 116. As in the previously described embodiments, the shank
15 114 is provided with four strain gauges 118. The strain gauges
118 are adhered to the surface of the shank 114 in circumferen-
.: tially spaced relation, their centers 90 degrees apart, and
altexnating in lateral and longitudinal orientation. The strain
gauges are part of a Wheatstone bridge circuit, as heretofore
described. ~ -
A portion of the stem 96.of the tie-down bolt 92, en- :
~ircled by the holl~w-cored portion of the spacer 106 is pro- :
vided with four strain gauges 120, adhered and disposed in the
~ame manner as those on the shank 114. As will be readily under-
stood, thè tie-down bolts 92 are subject to tensile forces as they
are tightened. Therefore, the stretching and shortening of the
~ine resistance wires in the strain gauges are the reverse of
.~ those caused by compressive force as exerted on the spacers 106.
Read out meters connected to the strain gauges 120 are, of course,
calibrated to show tensile forces in appropriate units such as
pounds or kilograms.
: ~ When a major unit of equiyment i~ to be mounted on
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~pacers 106 embodying my inv~ntion and bolted to a factory floor
with tie-down bolts 92, the first step in the leveling proce-
dure is to adjust the respective spacers 106 and, taking the
rsadings for the load force exerted on each such spacer and
turning each of the respective spacers, one at a time and as
necessary to obtain the desired weight equali~ation.
After distributing the load equally on the spacers
106, the nuts 108 are tightened against the washsers 110 on the
threaded stems 96 of the respective tie-down bolts 9~. By watch-
ing the read-out of the tensile force on each tie-down bolt 92,
the hold down pressure on each such bolt can be equalized, thus
giving control over the tightness with which the unit of equip-
ment is held down at each of its mounting points.
For some equipment installations, it is desirable to
obtain constant read-out of the dynamic forces exerted during
operation at each mounting point. This may be done by integrat-
ing the circuits from 'he strain gauges 118 on the spacers 106
and the strain gauges 120 on the tie-down bolts 92 so that the
signals showing tensile forces exerted upon the respective tie-
dnwn bolts 92 are subtracted from the compressive orce signals
from the corresponding spacers. Such integration enables direct
read-out of the dynamic force exerted at each mounting point
elther continuously or at selected intervals during an operation
cycle.
/It will be understood that the embodiments of my inven-
tion as shown and described herein are exemplary o~ preferred
forms thereof. It will be apparent, however, to persons silled
- in the art that diverse modifications and embodiments are within
the contemplation of my inventive concept, the scope of which is
to be determined by the appended claims.
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