High speed transporting and weighing machine with dynamic balance

There is disclosed a machine for transporting and weighing or checkweighing articles passing in succession thereon at high speeds, such as for use in conjunction with a rapid article feeding and take-away conveyor system or the like and with weight-signal transmitting/converting/calculating printout devices for visual display and price labeling operations or the like. The machine includes a stationary machine base and a vertically flexible weight-measuring means supported by said base. A rigid cage-like structure encompasses and is supported by said weight-measuring means, and an article conveying device and a power supply means therefor is carried by said cage-like structure and comprises in combination therewith the minusculely vertically shifting tare weight component of the machine. The conveying device and the power supply means and the construction elements of the cage-like structure are so weight-related and positioned in the cage-like structure as to be substantially statically balanced and in equilibrium about the axes of the weight-measuring means. Therefore, the measuring means is shielded from effects of transitory force impingements upon the tare weight assembly such as would otherwise induce torque moments to operate on the assembly about the axes of the measuring means.

BACKGROUND AND OBJECTS OF THE INVENTION 
This invention relates to high speed operating weighing/conveyor machines 
such as are used in the food and other commodity 
packaging/weighing/checkweighing industries or the like. Prior machines 
for such purposes are disclosed for example in U.S. Pat. Nos. 2,838,176; 
3,070,214; 3,180,475; 3,955,665 and 4,114,707. 
More particularly, the invention relates to so-called powered platform 
scales, such as are used in systems for weighing discrete articles being 
conveyed in succession at high speeds over a weighing device; the "net" 
weights of which in most cases are to be visually displayed and 
graphically recorded. Also, in some cases such measurements are used to 
control devices for rejection from the delivery line of underloaded or 
overloaded packages or containers, as is well known in the art. The weight 
detecting/reporting components of such prior machines are subjected to 
dynamic error inductive influences such as are not encountered by 
"stationary" platform type weighing machines. 
Prior machines for such purposes have typically comprised vertically 
"stacked" structural assemblies, at the bases of which reside the load 
cell or other weight-measuring component which is surmounted by the 
article transport weighing conveyor which is driven by an externally based 
motor and drive system. Such assemblies are accordingly statically 
imbalanced and top-heavy and therefor inherently subject to magnification 
of typically encountered dynamic unbalancing forces which when transmitted 
to the article weight detecting mechanism result in inaccurate weight 
measurement reports. Also, such encounters may apply physically 
destructive forces upon the mechanism such as call for constant 
maintenance attention; shut-downs, and repair expenses. 
Such unbalancing impulses may be introduced for example by environmental 
shop noises; conveyor belt flutterings; drive chain or belt chatter 
vibrations; vagarious placements on the conveyor of the items to be 
weighed, and the intermittent item on-loading/off loading effects on the 
conveyor such as tend to disrupt smooth running operations of the 
conveyor. In prior machines, such impulses develop into torque moment 
forces and on occasion acquire resonance, and operate through substantial 
leverages relative to weight-measuring mechanism; thereby interfering with 
accurate readings especially in the case of high speed operations. 
The present invention features a unique system for mounting the masses of 
the loads-carrying conveyor mechanism thereof as well as its motor and 
power train components relative to the weight-measuring component(s) 
thereof. This enables the machine to operate at higher speeds (and 
therefore higher capacities) compared to machines previously available to 
the industry, while correctly reporting the net weights of items such as 
are fleetingly conveyed in succession thereover. 
BRIEF SUMMARY OF THE INVENTION 
This invention provides means whereby typically encountered operational 
disturbances such as are referred to hereinabove are more effectively 
nulled relative to the weight-measuring mechanism of the system, whereby 
to provide a more accurate weight reporting system of increased capacity. 
This is accomplished by integrating and locating the requisite tare weight 
components thereof such as include the conveyor carrying the items to be 
weighed; its power supply motor and transmission system and the supportive 
structures into a cage-like cradle assembly (which minusculely shifts 
vertically incidental to each weight-measuring operation). 
This cage assembly is structured so as to be per se substantially 
statically balanced, and either rests upon or is suspended from the 
weight-measuring mechanism of the system which is mounted on a stationary 
base. The components of the cage assembly are weight-related and so 
located and spaced "in orbit" about the central axes of the weight 
measuring device as to be substantially in three-dimensionally statically 
balanced mode thereabout. Therefore, such above referred to extraneous and 
otherwise torque-inducing forces acting upon any part of the cage 
assembly, are in the case of this invention substantially counterbalanced 
out by reason of which the weight-measuring component of the system is 
shielded from the effects of such forces. Accordingly, more accurate 
weighing reports under higher speed (capacity) conditions are available to 
the industry. 
Incidentally, machines of the invention may preferably employ load cells of 
the type which are per se designed to be resistant to extraneously 
generated torque-inductive stresses on the strain-gage component thereof, 
in order to attain optimum advantages of the improvement features of the 
present invention. The invention also provides an improved conveyor roller 
supporting arrangement which is hingedly mounted and latched into 
operative position, so that it is readily swingable out of its operative 
position. Thereupon, the endless elastic conveyor belt thereof may readily 
be "peeled" away from its mounting rollers for system component cleaning 
and/or belt replacement purposes.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
FIG. 1 of the drawing herewith is furnished by way of a perspective 
illustration of a typical high speed operating weighing or 
checkweighing/conveying machine incorporating one preferred form of the 
present invention. This is shown in operative conjuction with a 
commercially available analog-digital converter such as Model 710B 
marketed by the Quest Corporation of Macedonia, Ohio. Several such 
suitable weight reporting/transfer systems are presently available, and 
per se form no part of the present invention. As shown herein by way of 
example, the weighing or checkweighing/conveying component of the 
invention is designated generally by the numeral 10 and comprises an 
endless conveyor belt 12 carried by opposite end pulleys supported upon 
frame support panels 14,16. 
Machines of this type are adapted to accommodate fleetingly received and 
discharged successions of discrete articles as they pass over the conveyor 
and to report to the auxiliary attendant analog-digital converter such as 
shown at 18 for coincident price per pound/weight/total cost of each item 
calculations for deliveries to the visual and tape recording devices of 
the console, such as is shown at 20. Suitable electrical power input and 
weight signal transfer arrangements (such as are designated generally by 
the numeral 22) and such as are well known in the industry are employed as 
auxiliaries to the system, and are only incidental to the present 
invention. 
FIGS. 2-5 illustrate embodiment of the invention in a weighing or 
checkweighing/conveyor type machine of a somewhat different form compared 
to that shown in FIG. 1. In this case, by way of example, the base machine 
support may comprise a pair of upright standing parallel side wall frame 
panels 30,30, which are structurally interconnected into an open-ended 
box-like form at their upper level such as by means of a transverse strut 
32 and machine screws 33,33; and at their lower level by struts 34,34 and 
machine screws 35. As best shown in FIGS. 4 and 5, the conveyor belt 12 is 
carried by rollers 36,37 which are endwise rotatably mounted by means of 
axies 38,39 upon a cradle-like chassis or cage which is designated 
generally by the numeral 40. The cage 40 comprises a pair of opposite side 
wall-like panel members 42,44 which extend longitudinally in parallelism 
with the conveyor belt 12. Transversely disposed struts 46,46 and a bottom 
plate 48 are provided as shown to form a box-like cradle, at the upper 
level of which is mounted the conveyor 12 by means of the rollers 36,37. A 
conveyor belt slide plate as shown at 50 (FIGS. 2-4 and 7) provides the 
"roof" of the chassis structure 40. 
A conveyor driving motor as shown at 52 is mounted by means of bolting the 
motor base plate 54 to the bottom of the cradle bottom plate 48; the motor 
being thereby suspended therefrom such as by means of bolts 56,56. The 
motor unit includes a drive speed reduction gear box as shown at 58 from 
which extends the output shaft 59 carrying the belt drive pulley 60. The 
drive belt is shown at 62 and trains around a pulley 64 which is keyed to 
the shaft 39 carrying the conveyor roller 37. Preferably, the bolts 56,56 
are accommodated within slotted portions 66 (FIGS. 4 and 5) of the bottom 
plate 48 extending transversely thereof in order that the motor/gear box 
unit may, if desired, be shifted laterally of the chassis center line for 
purposes to be more fully explained hereinafter. 
Thus, it will be appreciated that the relatively heavy components of the 
system, such as the above-board conveyor and below-board driving motor, 
are so relatively located in the cage assembly as to substantially 
counterbalance each other. This assembly, including the conveyor and its 
driving mechanism, as well as the supportive cage structure, represents 
the tare weight of the system over which pass items to be weighed such as 
are shown at 70. For example, such items may be delivered to the conveyor 
belt 12 as by a delivery conveyor 72 and discharged to a takeoff conveyor 
74 as shown at FIGS. 2 and 3. As shown herein further by way of example, 
the delivery conveyor may be of the endless belt type carried by rollers 
as shown at 76 journalled on the side frame plates 30,30; and the takeoff 
conveyor 74 may similarly be of endless belt form carried by rollers also 
journalled on the side plates 30,30. However, it is to be understood that 
the item delivery and takeoff mechanisms form no part of the present 
invention and may be of any other suitable form and totally separate from 
the machine of the invention. 
The cage assembly including the entire tare weight components of the system 
is suspended from and mass-centered about the weight-measuring device 
which in this case is shown to be by way of example of the sometimes 
referred to "leverless type" load cell, and which is shown generally at 80 
(FIGS. 4, 4a, 5 and 5a). Such load cells are currently available on the 
market and are structured and operate as explained for example in U.S. 
Pat. Nos. 4,143,727 and 4,146,100. In the drawing herewith at FIGS. 4 and 
5, such a load cell is shown schematically at 80 to comprise a beam 
component 82 fixed to the cradle support bar 32 such as by means of a 
machine screw 83; an intermediate strain-gage component 84 and a lower 
beam component 86, which is affixed as by means or a machine screw 87 at 
one end to the cradle base plate 48. Thus, the entire cage assembly is 
suspended from the cross bar 32 by way of the load cell unit 80, whereby 
the strain-gage section 84 of the load cell is variously stressed in 
accordance with gross weight changes due to variations in the weights of 
the articles being transported by the conveyor 12. Such stress variations 
on the strain gage cause corresponding signal changes to be sent to the 
analog-digital converter 18, which may be of any suitable commercially 
available type and operates to translate the voltage outputs from the 
strain-gage transducer to weight-in-pounds readings on the display 20 
(FIG. 1). 
It is a particular feature of this invention that as best illustrated at 
FIGS. 4a and 5a, the entire assembly which is minusculely vertically 
movable incidental to each weighing process (which comprises the gross 
weight of the system and includes the load to be weighed as well as the 
cage and its supported components) is substantially statically 
mass-centered and in equilibrium about the force-reactive axes of the load 
cell. This movable assembly is depicted by the shaded portion of FIGS. 4a 
and 5a with a view to graphically differentiating it vis-a-vis the 
stationary structure of the system. External disturbances effective 
against the movable assembly such as would otherwise apply transient 
torque forces to the load cell system and such as would disrupt accurate 
measurements of the weights of the items being transported by the conveyor 
are accordingly inoperative to influence accurate functionings of the load 
cell system. Hence, the machine may be operated at higher speed (capacity) 
than prior art machines while still providing at least equal or improved 
weight reporting accuracies. 
As best shown at FIG. 7, the conveyor belt slide plate 50 is margined by 
down-turned flange portions 51,51 which are fixed as by means of devices 
51a to side rails 88,89 which lie along the tops of the cradle side plates 
42,44 respectively. Rail 89 is hingedly connected as shown at 90 to cradle 
side plate 44 and the rail 88 is equipped with pivotal latch members 91,91 
for detachable locking arrangements with the cradle side plate 42. As best 
shown at FIG. 6, the latch devices 91,91 which are pivotally mounted on 
the rail 88 such as by means of U-shaped pivot pins 91a, are barb-shaped 
at their lower ends 92 for engagement with spear-shaped abutments 93,93 
which are affixed to the side plate 42, and arranged to be upwardly biased 
by means of tension springs 94. Thus, the latches as shown may be of the 
downwardly depressable types for release of the rail 88 from the side 
plate 42. However, it is to be understood that any other suitable type of 
manually releasable latch arrangement may be employed for locking the rail 
88 relative to the side plate 42 during operation of the machine. 
Thus, as shown at FIGS. 5 and 6, in order to facilitate machine clean-out 
and/or conveyor belt replacement purposes, the latches 91,91 may be 
released so that the conveyor belt pulley 64 may be upwardly inclined 
about the hinge mechanisms 90. The elastic endless conveyor belt may then 
be readily slid laterally away from the conveyor roller to provide for 
access to the interior of the machine and/or for belt replacement 
purposes. 
FIGS. 8 and 9 herewith illustrate another preferred form of the invention 
such as is also shown at FIG. 1, wherein the tare weight cage structure is 
designated generally at 140 and mounts a conveyor belt designated 112 by 
means of rollers 136,137 carried by axles 138,139. The chassis comprises a 
pair of opposite side wall panel members 142,144 which are interconnected 
by means of transverse struts 146,146 and a bottom plate 148 secured as by 
means of machine screws 149,149 to form a box-like cradle. A conveyor belt 
slide plate 150 is also provided as in the case of the machine of FIGS. 
2-5 to form the "roof" of the chassis structure upon which the top flight 
of the conveyor belt 112 slides. 
In this case, the conveyor drive motor and gear box units are designated 
152,158 and set upon the base plate 148 and are positionally adjustable 
thereon and locked in place such as by means of bolts 149a,149a (FIG. 9). 
The conveyor 112 is driven by means of drive belt 162 (FIGS. 9 and 9a). 
However, the cage 140 and its supported components are in turn supported 
relative to a bottom plate 200 by means of shoulder pads 202,202 which are 
fixed such as by machine screws 204 to extend laterally from the side 
plates 142,144 of the cage as best shown at FIG. 9. These shoulder pads 
rest upon and are affixed to the upper beam components 182,182 of a pair 
of load cells which are designated generally at 180,180 and which are 
disposed at opposite sides of the machine; the lower beam components 
186,186 thereof being based upon support blocks 206,206 which are carried 
upon opposite sides of the bottom base plate 200. The support blocks 
206,206 rest upon the bottom plate 200 and the bottom plate is vertically 
adjustable on the machine base 210 such as by means of machine screws 
212,212 and lock nuts 214,214. 
As in the case of the machine of FIGS. 2-7, the total of the gross weight 
components of the assembly, including the conveyor, the conveyor drive, 
the cradle structure and the item being weighed as a unit is substantially 
statically mass-centered relative to the load cells 180,180 and as close 
as is practically possible about their operational axes. This may be 
effected upon initial assemblies of the machines having in mind the 
approximate weights of the items to be handled by the machine. However, as 
shown in FIGS. 2-7, the mounting bolts 56 and 83 permit the machine to be 
more finely adjusted to accommodate the weighing of items of various 
weights. The bolts 149a,149a permit adjustments for similar purposes of 
the machine of FIGS. 8 and 9. Whereas FIGS. 8 and 9 show employment of 
paired load cells operating under compression, it will of course be 
understood that such a dual cell arrangement may optionally be constructed 
so as to employ load cells of the tension type, such as shown in FIGS. 
2-7. 
It is of particular note that in any case employment of paired load cells 
located on opposite sides of the conveying-weighing system provides an 
improved facility for efficiently accommodating laterally vagarious 
placements of items to be weighed upon the conveyor component of the 
system. This problem typically occurs incidental to the handling in 
succession of erratically shaped/sized items of various weights. Also, 
this form of the machine of the invention may be built to more effectively 
accommodate wider conveyor belts, and therefore larger articles to be 
weighed, than other machines. In the case of the present invention, such 
differential loadings of the conveyor belt at opposite sides thereof are 
effectively nulled out; whereby accurate weight readings are nevertheless 
signalled to the associated display/recording/pricing devices or the like. 
FIG. 10 illustrates schematically another modified form of machine 
embodying the invention such as may be better adapted to handle larger 
size items such as are shown at 270. The machine may be of either the 
single or dual load cell type such as are illustrated by FIGS. 2-7, 8 and 
9, respectively, and is shown to comprise a conveyor 272 carried by side 
plates 274 which in turn are supported on a plurality of longitudinally 
in-line load cells such as are shown at 275,275. In such case, the signals 
from the load cells to the weight/price reporting converter system will be 
summed; and thus it will be appreciated that such a machine is of improved 
longitudinal stability characteristics when handling larger size items.