Apparatus for controlling the filling of weigh pans

An apparatus for selecting between a mechanical or electrical mode for controlling the flow of fibers by motor driven feed lift aprons from a plurality of hoppers to a plurality of weigh pans for producing a predetermined blend of fibers. The mechanical mode utilizes a balance arm assembly which can be set to feed a predetermined amount of fibers into a weigh pan. The electrical mode utilizes thumbwheel switches which can be set for regulating the amount of fibers to be fed into each weigh pan. The electrical mode system also utilizes a comparator for comparing a signal representing the actual weight of fibers in the weigh pan that is produced by a load cell with a signal representing the desired weight of fibers produced by the thumbwheel switches and generates a control signal responsive thereto. The control signal is used for operating a motor driven feed lift apron associated with the hopper.

BACKGROUND OF THE INVENTION 
In normal blending operations, fibers are fed by means of lift aprons from 
hoppers into weigh pans. The weigh pans are equipped with balance arm 
assemblies which are used for measuring the weight of fibers being 
deposited into the weigh pan and for stopping the feeding of fibers into 
the weigh pan upon a predetermined weight being deposited therein. After 
all of the hoppers have received a predetermined weight of fibers therein, 
doors associated with the weigh pans are opened allowing the fibers from 
the plurality of weigh pans to be deposited on a conveyor belt to form the 
desired blend. 
One particular apparatus for feeding textile fibers in a uniform stream is 
disclosed in U.S. Pat. No. 3,132,709. As can be seen therein, the weigh 
bar assembly is used for setting the desired weight of fibers that are to 
be deposited in a particular weigh pan. Upon the desired weight being 
deposited in the weigh pan, and electric switch is activated, 
de-energizing the motor associated with the hopper feed lift apron. The 
device disclosed in this particular patent is normally referred to as a 
mechanical device for weighing the fibers being deposited into weigh pans 
even though an electrical switch is used in combination with a weigh bar 
assembly for contolling the operation of the motor driven feed lift apron. 
In order to monitor and provide a record of the fibers that are dropped by 
weigh pans onto a belt in order to determine the blend of the fibers, 
electronic monitoring systems have been utilized. One electronic 
monitoring system is disclosed in U.S. Pat. No. 4,310,060. In this 
particular device, load cells are carried between the hopper and the weigh 
pan for generating electrical signals indicating the weight of the fibers 
that is fed into the weigh pan. These signals are, in turn, converted from 
analog signals to digital signals and displayed on a digital display. 
Similar signals are also fed to a chart recorder for making a permanent 
record of the individual drops of fibers made by the weigh pan. 
Apparently there have been many other attempts to solve the problem of 
monitoring the flow of fibers from a plurality of hoppers to a conveyor in 
order to control the blend, however, most of them have not been made 
commercially available. One such device is disclosed in U.S. Pat. No. 
3,918,538. 
There have been other attempts to control the flow of fibers to a weigh 
pan, however, to applicant's knowledge, no one has provided a system for 
selectively switching from a mechanical weighing system such as shown in 
U.S. Pat. No. 3,132,709 to an electronic weighing and controlling system 
in a simple manner without adversely affecting the operation of the 
mechanical weighing systems. 
SUMMARY OF THE INVENTION 
The apparatus constructed in accordance with the present invention makes 
available an apparatus which is simple and reliable for either 
mechanically or electrically controlling the filling of weigh pans and a 
method for selectively switching from one system to the other. 
In the apparatus constructed in accordance with the present invention, the 
flow of fibers are fed by a motor driven feed lift apron from a plurality 
of hoppers to a plurality of weigh pans for producing a predetermined 
blend of fibers. A balance arm assembly is used for mechanically setting a 
predetermined weight of fibers to be fed from a respective hopper to a 
respective weigh pan. The apparatus is also provided with a load cell for 
electrically monitoring the respective dumps of fibers from the weigh pans 
onto a blending conveyor. 
A rotatably mounted crank arm is carried adjacent the balance arm assembly 
for physically locking the balance arm assembly in an inoperative position 
when rotated to a first position. A switch means is activated by the 
rotatably mounted crank arm for selectively activating an electrical 
system for controlling the flow of fibers to the weigh pans by selectively 
turning on and off the motor driven lift apron. Once the desired weight of 
each dump of fibers by the particular weigh pan is determined, this 
information is set for that particular weigh pan by manipulating 
thumbwheel switches or the like to indicate the desired weight. A 
comparator means is used for comparing the signal produced by the 
thumbwheel switches corresponding to the desired weight of fibers that are 
to be fed into a weigh pan with a signal produced by the load cell 
corresponding to the actual weight of fibers in the weigh pan. The 
comparator means generates a control signal responsive thereto. This 
control signal is, in turn, used for energizing the motor driven feed 
apron for controlling the filling of fibers into the weigh pan. 
The weight of the dumps of fibers onto the conveyor are also recorded in 
the same manner as described in U.S. Pat. No. 4,310,060. 
Accordingly, it is an important object of the present invention to provide 
an apparatus which can be readily changed from mechanically to 
electrically controlling the flow of fibers from a hopper to a weigh pan. 
Another important object of the present invention is to provide a simple 
and reliable system for either mechanically or electrically filling weigh 
pans and for selectively switching between the two control systems. 
Another important object of the present invention is to provide an 
apparatus for converting mechanically controlled fiber filling systems 
associated with weigh pans to an electrically controlled system and vice 
versa without destroying or interfering with the integrity of the 
mechanically controlled system. 
The construction designed to carry out the invention will be hereinafter 
described, together with other features thereof. 
The invention will be more readily understood from a reading of the 
following specification and by reference to the accompanying drawings 
forming a part thereof, wherein an example of the invention is shown and 
wherein:

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to FIG. 1 there is illustrated a control panel for the circuitry 
used in controlling and monitoring filling of fibers into a plurality of 
weigh pans which, upon being filled to a predetermined weight, drops the 
fibers onto a receiver. Positioned on the front of the control panel are 
switches 10, 12, 14, 16 18, and 20 which can be set to visually indicate 
the desired weight of fibers that is to be filled in a respective weigh 
pan. The actual weight of the fibers in a respective weigh pan is 
indicated in the panels 10a, 12a,etc. Each of the weigh pans 22, 24, 26, 
28, 30, and 32 have individual selection switches 10 through 20 which may 
take the form of thumbwheel switches that are used for controlling the 
amount of fibers that are to be filled from the respective hoppers. After 
all of the weigh pans 22 through 32 have been filled with the desired 
amount of fibers, the fibers are dumped onto a receiving conveyor belt 36. 
The operation of the dumping mechanism is described in more detail in U.S. 
Pat. No. 3,132,709. 
Other indicating mechanism can be provided on the panel such as alarm 
lights which indicate if a particular drop is above or below the desired 
weight for the particular drop. Similar functional lights can also be 
provided in the box 38 carried on the side of the chart recorders 54. The 
chart recorders 54 are provided for recording the weight of each drop of 
fibers being made by the weigh pans. 
In FIG. 3, there is shown schematically a conventional hopper 44 equipped 
with a weigh bar assembly 40. One end of the weigh bar assembly is 
connected by means of rod 42 to a conventional weigh pan 22. The desired 
amount of fibers that are to be fed into the weigh pan 22 from the hopper 
44 is set by manipulating the slide weight 46 carried on the weigh bar 
assembly 40. When the desired amount of fibers are filled into the weigh 
pan 22, the weigh bar assembly under normal operation will tilt allowing 
the left hand end to drop and de-energize switch 48. Upon de-energization 
of switch 48 in normal operation of the mechanically controlled system, a 
hopper feed lift apron motor 96 associated with the hopper 44 is 
de-energized stopping the feeding of fibers into the weigh pan. 
The details of operation of the switch 48 and the hopper lift apron motor 
are given in U.S. Pat. No. 3,132,709. 
In order to accurately monitor the weight of each drop of fiber made by the 
mechanically operated system, a monitoring circuit such as disclosed in 
U.S. Pat. No. 4,310,060 was developed. This system utilized a load cell 52 
that generated an electrical signal indicating the weight of the fibers 
fed into the weigh pan 22 and causes this weight to be recorded on a chart 
recorder 54 immediately prior to the fibers being dumped. In FIG. 2, doors 
56 associated with the weigh pans are shown in the open position whereas 
in FIG. 3, the doors 56 are shown in the closed position. The doors 56 are 
opened and closed by manipulating a pneumatically operated cylinder 58 
which has a piston connected to pivot arms 60. The doors 56, in turn, 
pivot about pivot points 62 during the opening and closing operation. 
Going back to the operation of the monitoring system, the load cell 52 
generates an electrical signal indicating in the form of an analog signal 
the gross weight of the particular weigh pan and fibers loaded therein. 
This signal is, in turn, fed to an analog-to-digital converter 57 which 
converts the signal into a composite digital signal. A subtractor 59 is 
connected to the output of the analog-to-digital converter 57 for 
subtracting the weight pan from the digital signal. The subtractor 59 has 
a pair of output leads 61 and 63. Output lead 61 is fed directly to a 
display panel 64 which visually displays the net weight of the fibers 
being loaded into the weigh pan in ounces and tenths of ounces. 
The digital signals appearing on output leads 61 and 63 change constantly 
as the fibers are being loaded into the weigh pan and the reading produced 
by the digital display 64 varies accordingly. In order to produce a 
permanent record of the weight of the fibers dropped each time the doors 
are opened and drop fibers onto a conveyor, an additional control circuit 
is used to which the output lead 63 is connected. The digital signal 
representing the net fibers appearing on lead 63 is fed to a latch control 
circuit 66. When all of the weigh pans have been loaded with a 
predetermined weight of fibers, a signal is produced by the conventional 
circuitry associated with the weigh pans indicating that all of the weigh 
pans are ready to drop. After a short delay built into the circuit, all of 
the weigh pans drop the fibers onto the conveyor 36 simultaneously. This 
signal is used as a latch control signal for triggering the latch control 
circuit 66. Upon triggering of the latch control circuit 66, the digital 
reading that is supplied thereto is latched or stored into the circuit. 
This represents the net weight of fibers being dropped by a particular 
weigh pan. A digital to analog converter 68 is connected to the latch 
control circuit 66 for converting the digital signal latched therein back 
to an analog signal. The analog signal produced by the digital-to-analog 
converter 68 is fed out over lead 70 to a chart recorder pen control 
circuit 72. According to the amplitude of this analog signal, the pen 
associated with the chart recorder 54 is deflected and records the weight 
of the drop in the form of a mark on the chart paper. 
The chart recorder is a conventional chart recorder provided with 
adjustable knobs 74 and 76. These knobs are utilized for setting the 
maximum and minimum tolerances allowed for each drop. If the weight of the 
fibers dropped is below the minimum setting of knob 74 or above the 
maximum setting of knob 76, then a respective lamp is illuminated and an 
alarm is activated by an alarm circuit 77. When the alarm circuit is 
activated, a lamp normally carried on control panel is illuminated and an 
alarm relay is energized. 
As previously mentioned, when it is desired to mechanically control the 
filling and dropping of fibers by the weigh pans 22, the slide weight 46 
is moved along a slide bar 78 until the desired weight is determined. The 
slide bar 78 can pivot about pivot member 80 and upon the feed hopper 44 
depositing a predetermined amount by weight of fibers into the weigh pan 
22 corresponding to the setting on the slide weigh bar assembly, the pivot 
arm 78 pivots de-energizing switch 48 which is associated with the hopper 
feed lift apron motor. 
While in many applications, the mechanical control feeding and dropping of 
fiber works satisfactorily, it has been found that electrically measuring 
and controlling the operation of the weigh pan through the use of load 
cells is more accurate. 
In the electrical system, the desired amount of fibers that are to be 
filled in a particular weigh pan is manually set in an electrical switch 
that may be any suitable switch that can be manually set such as 
thumbwheel switch 79. This thumbwheel switch 79 generates an electrical 
signal that is fed over lead 81 to a weight comparator 82. The weight 
comparator has another imput which receives a signal from the subtractor 
59 over lead 84 which represents the actual weight of the fibers in the 
weigh pan. The signal representing the actual weight of fibers in the 
weigh pan is compared with the signal representing the desired weight of 
fibers and the comparator generates a control signal on lead 86. This 
control signal is, in turn, fed to a controller 88. The output of the 
controller 88 is connected to one terminal 90 of a manually operated 
microswitch 92. The microswitch 92 can be selectively moved from terminal 
90 to 94. As can be seen, terminal 94 is connected to the electrical 
switch 48 associated with the mechanical weigh bar assembly 40. When the 
microswitch is in a position so that there is connection with terminal 94 
the system operates in the conventional manner associated with the 
electromechanical weighing and dumping of fibers. In order to disengage 
the weigh bar assembly 40, the microswitch 92 is shifted to the left 
wherein it is in contact with terminal 90, and the output signal from 
controller 88 controls the operation of the hopper feed lift apron motor 
96. 
Therefore, as long as the signal coming into the weight comparator over 
lead 84 representing the actual weight of the fibers in the weigh pan 22 
is less than the signal dialed in the thumbwheel switches 79, the hopper 
feed lift motor will continue to feed fibers into the weigh pan. When the 
desired weight is equal to the actual weight, the controller 88 produces a 
signal deenergizing the hopper feed lift apron motor in the same manner as 
the switch 48 associated with the weigh bar system. 
The means for disengaging the weigh bar system (FIG. 4) includes a pivotal 
arm 98 which is carried in a housing 100 provided on the side of the 
hopper. The arm 98 is connected directly to a shaft 102 which extends 
through the housing 100. On the other end of the shaft are two friction 
nuts 104 and 106 which are carried on opposed sides of the wall 108 of the 
housing. As a result, the handle 98 has to be physically rotated and 
because of the frictional contact of the nuts 104 and 106 with the side 
wall remains in this position and is capable of holding the weigh bar 78 
in a raised position such as shown in FIG. 4 disengaging it completely 
from the circuit. It is also noted that the shaft 102 has a slot 110 
provided therein. This slot 110 receives a plunger 112 of the switch 92. 
When the arm 98 is raised to the phantom line position shown in FIG. 4, it 
lifts the weigh bar 78 physically upward eliminating its operation from 
the circuit. Simultaneously, with the raising of the arm 98, the shaft 102 
is rotated causing the plunger 112 associated with the switch 92 to shift 
from terminal 94 to 90 thus placing the electrical weighing system in 
action. As a result by visually examining the position of the arm 98, it 
can be determined whether the mode of operation of the system is 
electromechanical or purely electrical. 
While a preferred embodiment of the invention has been described using 
specific terms, such description is for illustrative purposes only, and it 
is to be understood that changes and variations may be made without 
departing from the spirit or scope of the following claims.