Vibrating screw feeder

A vibratory screw feed apparatus is provided for delivering controlled rates of particulate materials. The apparatus includes a double walled plastic trough having an open-topped upper recess. A hopper is removably mounted to the top of the trough for feeding particulate materials into the opened top upper recess. The trough further includes a bottom recess. A vibrator is mounted within the bottom recess. A screw feed assembly extends through the trough for feeding particulate material from the trough.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The subject invention is directed to a screw feeder for particulate 
materials. 
2. Description of the Prior Art 
Many manufacturing processes, such as processes performed in the chemical, 
pharmaceutical or food industries utilize particulate materials. The 
particulates may take the form of pellets, flakes, powders or fibers. 
Efficiency in the manufacturing process requires delivery of these 
particulates with speed and accuracy. 
Particulates present unique product delivery problems that have been 
considered in industry for many years. More specifically, particulates may 
interfere with one another and prevent a pure gravitational flow 
comparable to the gravitational flow of liquids. Screw feeders can 
transport articulate materials horizontally. However, the rate of flow of 
particulates through a screw feeder is affected by the rate of flow of 
particulates into the screw feeder. The prior art includes particular 
feeders that rely upon vibration to achieve a continuous and accurate flow 
of the particulates. The vibration causes the separate particles to move 
relative to one another. This movement substantially prevents or minimizes 
interference between adjacent particles, and thereby ensures a continuous 
flow of the particulates. 
Manufacturing facilities often change the product being manufactured. These 
changes can affect the particulate feed system. For example, the required 
feed rate of the particulates may change. In other situations the 
particulate itself may be changed. Thus a feeder may be required to 
deliver pellets at a first feed rate on one day and then may be required 
to deliver a different particulate at a different rate on the next day. A 
good quality feed apparatus must be capable of making this transition 
easily and effectively. Additionally, the feed machines often have to be 
carefully cleaned between changes from one particulate material to 
another. For these reasons, it is desirable to provide a feed apparatus 
that can be disassembled and reassembled quickly and easily to accommodate 
changes from one particulate to another and to effectively clean the 
apparatus during those changes. 
Many manufacturing processees require a specified weight of a particulate 
material. The prior art includes a vibratory screw batch feeders. The 
prior art vibratory screw batch feeder employs the above-described 
vibrating screw technology to achieve a very efficient flow of particulate 
materials. Upon delivery of a specified amount of the particulate 
material, the operation of the feeder is terminated. The particulate 
material then is moved from the feeder for use in the manufacturing 
process. Very effective prior art vibratory screw batch feeders operate on 
a loss-in-weight principle. More particularly, a weighing device is 
incorporated into the base of the prior art vibratory screw feeder. A 
sufficient amount of particulate material is placed in the hopper of the 
feeder. The feeder then is operated, and the weighing apparatus functions 
to monitor the loss in weight. When the loss in weight equals the 
specified batch weight, the operation of the vibratory screw feeder is 
terminated. 
A lighter weight feeder can improve the accuracy of loss-in-weight systems. 
More particularly, a lighter weight feeder will result in a larger 
proportion of the weight sensed by the scale system being devoted to the 
weighing of the particulate material. Conversely, a smaller proportion of 
the sensed weight will be devoted to the light weight feeder. It has been 
determined by the inventors herein that weighing accuracy can be increased 
by employing a scale system dedicated more to weighing the material being 
processed and less to weighing the feed apparatus. A lighter weight feeder 
also can reduce initial delivery costs and can simplify movement of the 
feeder at the manufacturing facility. 
Government regulations define allowable noise levels in many manufacturing 
work places. Accordingly, there are advantages to reducing noise produced 
by any apparatus, including a vibratory screw feed apparatus. Government 
regulations also specify materials that can be used for various food grade 
processing applications. In this regard, prior art feeders intended for 
food grade applications generally cannot be formed from the standard 
carbon steel that is acceptable for most other applications. Manufacturers 
of prior art feeders typically have resorted to stainless steel to meet 
government regulations for food grade applications. Stainless steel 
feeders typically cost about one-third more than the comparable feeder 
formed from conventional carbon steel. 
A very effective feeder with a wide range of feeding applications is 
manufactured by Vibra Screw Inc. of Totowa, N.J. under the trademark 
Versifeeder. The Versifeeder includes a trapezoidally configured metal 
hopper having a large open top end and small open bottom end. The bottom 
end of the hopper is removably mounted to a metal trough. A vibratory 
apparatus is mounted externally of the trough and vibrates the trough and 
the hopper sufficiently to ensure a continuous gravitational flow of 
particulate material from the hopper into the trough. A screw feeder is 
rotatably mounted in the lower portion of the trough and is operative to 
deliver the particulate material from the trough to an external 
receptacle. 
Despite the commercial acceptance of the Versifeeder, it is desired to make 
a feed apparatus that is less costly and lighter weight. It also is 
desired to provide a feed apparatus that very effectively delivers 
vibrations to the trough and hopper without significantly adding to noise 
within the work place. It also would be desirable to provide a lighter 
weight feeder for loss-in-weight batch feeding operations so that the 
greater proportion of the sensed weight is devoted to the particulate 
material being fed, thereby increasing accuracy. 
SUMMARY OF THE INVENTION 
The subject invention is directed to a vibratory screw feed apparatus for 
efficiently and accurately delivering particulate materials. The apparatus 
includes a trough for receiving particulate materials, a hopper for 
delivering particulate materials to the trough, a vibrator assembly for 
vibrating the trough and the hopper to ensure a continuous flow of 
particulates into the trough and a screw feed assembly for removing 
particulates from the trough. 
The trough is molded from a thermoplastic material and include a top and a 
bottom. A plurality of outer walls extend from the top to the bottom and 
define an outer enclosure for the trough. The trough further includes a 
plurality of inner walls supported by the outer walls at the top of the 
trough. The inner walls extend downwardly from the top of the trough in 
spaced relationship to the outer walls to define an open-topped upper 
recess for receiving particulates delivered from the hopper. Portions of 
the inner walls adjacent to top of the trough may define a flared seat for 
receiving the hopper as explained further herein. Apertures may extend 
through the inner and outer walls at opposed ends of the trough for 
accommodating portions of the screw feed assembly and for enabling removal 
of the particulates from the trough. 
The trough may further include a lower recess defined by a plurality of 
bottom inner walls extending upwardly from the bottom of the trough toward 
the particulate recess. The walls of the lower recess are in spaced 
relationship to both the open-topped upper recess and to the outer walls, 
and define an enclosure for accommodating the vibrator assembly as 
explained further herein. 
The hopper of the apparatus also is formed from plastic and includes a 
plurality of side walls, a large open top and a small open bottom. The 
open bottom of the hopper may be tapered inwardly for sitting in closely 
nested engagement with the outwardly flared regions of the inner walls 
adjacent the open top of the trough. Thus, the bottom end of the hopper 
can be seated tightly in the open top of the trough. 
The apparatus may further include a seal at the interface of the trough and 
the hopper. The seal may be a gasket or an O-ring secured to either of the 
trough or the hopper at their respective interfaces. 
The apparatus may further include releasable connections for holding the 
hopper and the trough in their interengaged disposition. For example, a 
plurality of latches may be hingedly connected to either the trough or the 
hopper and may be rotated into latched engagement with the other of the 
trough and the hopper. 
The vibrator assembly is mounted to the trough, and preferably in the lower 
recess of the trough surrounded by the bottom ends of the outer walls and 
by the bottom inner walls of the trough. Thus, the vibratory apparatus may 
be completely concealed from view and protected from inadvertent contact 
by workers using the apparatus. Furthermore the double wall of the lower 
recess contributes to noise insulation. The vibrator may be of a known 
type, and may be operative to deliver vibrations to the trough and to at 
least the lower end of the hopper. The vibrator may be mounted to a steel 
plate bent into a substantially U-shape and secured in substantially 
face-to-face engagement with surfaces of the bottom inner walls directly 
beneath the upper recess and the screw as explained further herein. Thus, 
the vibrator causes vibrations to be transmitted to the steel plate which 
in turn transmits vibrations to the plastic of the trough and to the 
hopper. 
The screw feed assembly includes a generally cylindrical discharge tube 
extending through a pair of registered apertures in portions of the trough 
aligned with the upper recess. A screw extends through the discharge tube 
and substantially across the open-topped upper recess in the trough. A 
seal is mounted in an opposed pair of registered apertures in the inner 
and outer side walls of the trough and accommodates a drive shaft that 
engages with one end of the screw. A motor is mounted externally of the 
trough and is operatively connected to the drive shaft for rotatably 
driving the screw. The seal around the drive shaft preferably is 
adjustable for periodic tightening to ensure effective sealing despite 
wear due to long term use of the apparatus. Thus, leakage of powdered or 
particulate material around the drive shaft of the screw can be 
substantially prevented. 
The apparatus of the subject invention may adjustably accommodate different 
feed rates by adjusting the rate of vibration, by varying the speed of the 
screw and by replacing one screw with another of different dimensions. The 
apparatus of the subject invention also is particularly well suited for 
loss-in-weight batch feeding operations. More particularly, the plastic is 
relatively light weight as compared to the prior art metallic feeders, and 
as a result significantly greater weighing accuracies can be achieved. 
Furthermore, many plastics are suitable for food grade applications and 
provide significant cost advantages over prior art stainless steel 
feeders.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A vibratory feed apparatus in accordance with the subject invention is 
identified generally by the numeral 10 in FIGS. 1-3. The apparatus 10 
includes a trough 12, a hopper 14, a vibratory assembly 16 and a screw 
feed assembly 18. 
The trough 12 of the apparatus 10 is unitarily molded from a plastic 
material, such as polyethylene, to define a double wall construction, as 
shown most clearly in FIGS. 4 and 5. The trough 12 includes a top 20 for 
connection to the hopper 14 and a bottom 22 for secure mounting to a base 
23 as explained further herein. The base 23 includes a scale for 
loss-in-weight batch feeding operations, as explained above. External 
portions of the trough 12 between the top 20 and the bottom 22 are 
substantially rectilinear. In particular, the trough 12 includes 
substantially parallel first and second outer end walls 24 and 26 and 
first and second substantial parallel outer side walls 28 and 30. The 
outer end walls 24 and 26 are substantially orthogonal to the outer side 
walls 28 and 30. Additionally, the outer end walls 24 and 26 and the outer 
side walls 28 and 30 extend substantially continuously from the top 20 to 
the bottom 22 of the trough 12. 
The trough 12 further includes an open-topped upper recess 32 extending 
into the top 20 thereof. The upper recess 32 is defined by first and 
second inner end walls 34 and 36, first and second inner side walls 38 and 
40 and a cylindrically curved bottom wall 42. The first and second inner 
end walls 34 and 36 are substantially parallel to one another and 
substantially parallel to the outer end walls 24 and 26. However, portions 
of the first and second inner end walls 34 and 36 adjacent the top 20 of 
the trough 12 are flared outwardly and join with the respective first and 
second outer end walls 24 and 26 at the .top 20 of the trough 12. As a 
result, the first and second inner end walls 34 and 36 are disposed in 
spaced relationship to the respective first and second outer end walls 24 
and 26 at all locations except the extreme top 20 of the trough 12. The 
bottom wall 42 is disposed between the top 20 and the bottom 22 of the 
trough 12 and is cylindrically generated about an axis parallel to and 
centrally between the outer side walls 28 and 30. The first and second 
inner side walls 38 and 40 extend substantially tangentially from the 
bottom wall 42 and diverge from one another toward the top 20 of the 
trough 12. Portions of the side walls 38 and 40 adjacent the top 20 define 
steps for receiving the hopper 14 as explained herein. As shown most 
clearly in FIG. 5, the first and second inner side walls 38 and 40 are 
spaced from the respective first and second outer side walls 28 and 30 at 
all locations except the extreme top 20 of the trough 12. 
The trough 12 include a cylindrical drive support wall 44 extending from 
the first outer end wall 24 to the first inner end wall 34. The 
cylindrical drive support wall 44 is generated about an axis that extends 
substantially parallel to the top and bottom 20 and 22 of the trough 12 
and substantially centrally between the outer side wall 28 and 30. The 
cylindrical drive support 44 provides communication from external regions 
of the trough 12 into the recess 32. The trough 12 further includes a 
cylindrical outlet support wall 46 that extends between the second outer 
end wall 26 and the second inner end wall 36. The cylindrical outlet 
support wall 46 is generated about an axis coincident with the axis of the 
cylindrical drive support wall 44. As shown most clearly in FIG. 5, 
portions of the first and second outer end walls 24 and 26 near the 
cylindrical walls 44 and 46 project outwardly to provide lengths for the 
cylindrical walls 44 and 46 that are sufficient to ensure adequate support 
for a drive rod and a discharge tube as explained below. 
The bottom 22 of the trough 12 is characterized by a generally rectangular 
lower recess 48. The lower recess 48 includes a top wall 52 that extends 
substantially parallel to the top and bottom 20 and 22 of the trough 12 
and in spaced relationship to the cylindrically generated bottom wall 42 
of the open-topped upper recess 32. The lower recess 48 is further 
characterized by first and second bottom end walls 54 and 56 and first and 
second bottom side walls 58 and 60. The lower recess 48 accommodates the 
vibrator assembly 16 as explained further herein. 
As shown most clearly in FIG. 4, a plurality of mounting apertures 62 
extend into the bottom 22 at locations intermediate the outer walls 24, 
26, 28 and 30 and the lower recess 48. The mounting apertures enable 
mounting of the apparatus 10 to the base 23 as explained further below. 
The trough 12 further includes baffle supports 64 and 66 mounted to the 
first and second inner end walls 34 and 36 respectively at locations near 
the outwardly flare approaching the top of the trough 12. A baffle 68 of 
inverted V-shaped cross-section extends between the first and second inner 
end walls 34 and 36 in supporting engagement on the respective baffle 
supports 64 and 66. 
The hopper 14 includes an open top 70 and an open bottom 72. Portions of 
the hopper 14 between the top and bottom 70 and 72 include first and 
second end walls 74 and 76 and first and second side walls 78 and 80. The 
side walls 78 and 80 are substantially parallel to one another and 
substantially orthogonal to the end wall 74 and 76. Additionally, the side 
walls 78 and 80 and the second end walls 76 extend substantially 
orthogonal to the top and bottom 70 and 72 of the hopper 14. However, the 
first end wall 74 is angularly aligned to the second end wall 76 such that 
the top 70 of the hopper 14 defines a larger area than the bottom 72 
thereof. Regions of the hopper 14 adjacent the bottom 72 thereof are 
offset inwardly to define a mounting portion 82. The mounting portion 82 
terminates at a step 84. The mounting portion 82 is configured and 
dimensioned to nest with the outwardly flared surfaces on the inner walls 
34, 36, 38 and 40 adjacent the top 20 of the trough 12. The step 84 
defines a limit to this telescoped nested engagement of the hopper 14 with 
the trough 12 and further substantially prevents leakage of powdered 
material from the interface of the trough 12 and hopper 14. Leakage is 
further prevented by a gasket 86 disposed at the interface of the trough 
12 and hopper 14. Portions of the hopper 14 adjacent the top 70 thereof 
are characterized by an outward corrugation 88 extending entirely around 
the hopper. The corrugation 88 attributes to rigidity of the hopper 14. 
The vibrator assembly 16 includes a vibrator 90 having an eccentric axis of 
rotation aligned substantially parallel to the axes about which the 
cylindrical walls 44 and 46 are generated. The vibrator assembly 16 
further includes a steel mounting bracket 92. The mounting bracket 92 is 
of generally U-shape and includes a generally planar top wall 94, first 
and second side walls 98 and 100 and first and second mounting flanges 102 
and 104 respectively. The mounting flanges 102 and 104 are disposed 
adjacent the bottom 22 of the trough 12 and include apertures that align 
with the apertures 62 in the bottom 22 of the trough 12. Thus, the 
mounting bracket 92 can be securely affixed between the bottom 22 of the 
trough 12 and the base 23. The vibrator 90 is securely connected to the 
top wall 94 of the mounting bracket 92 by a plurality of bolts as shown in 
FIGS. 2 and 3. Vibrations from the vibrator 90 are transmitted through the 
top wall 94 of the mounting bracket 92 and into the mounting flanges 102 
and 104. In this manner, vibrations are further transmitted into the 
double-walled trough 12 and portions of the hopper 14 adjacent the bottom 
end 72 thereof. 
The screw feed assembly 18 of the apparatus 10 includes a helically 
generated screw 106 extending substantially coaxially with the cylindrical 
walls 44 and 46 of the trough 12. The screw 106 include opposed ends 108 
and 110. Portions of the screw 106 adjacent the end 110 extend centrally 
through a feed tube 112. The feed tube 112 is mounted in a cylindrical 
bushing 114 which is closely engaged in the cylindrical outlet support 
wall 46 of the trough 12. Particulate material in the open-topped upper 
recess 32 of the trough 12 will be delivered by the screw 106 through the 
feed tube 112 and into an external receptacle (not shown). 
The first end 108 of the screw 106 is removably mounted to a drive shaft 
116. The drive shaft 116 extends through a seal assembly 118 which is 
mounted in the cylindrical drive support wall 44 of the trough 12. 
Portions of the drive shaft 116 externally of the trough 12 and externally 
of the seal 18 are rotatably driven by a motor 120. Rotation of the drive 
shaft 116 will cause the screw 106 to rotate about its axis and to deliver 
powdered or particulate material from the open-topped upper recess 32 in 
the trough 12 through the feed tube 112. Continued operation of the 
apparatus 10 invariably will cause wear of components within the seal 118. 
As a result, the seal 118 preferably includes a plurality of V-rings that 
are biased against the drive shaft 116. The seal 118 can be tightened, by, 
for example, threaded elements therein to urge the V-rings 122 toward one 
another, thereby biasing the V-rings both inwardly and outwardly into 
tighter sealing engagement against the drive shaft 116. Other seals may be 
employed in place of the seal 118, such as seals that do not employ the 
plurality of V-rings shown in FIG. 6. 
In use, a feed tube 112 and a screw 106 for a particular application are 
selected and are mounted in the cylindrical outlet wall 46 of the trough 
12. Feed screws 106 of a smaller diameter will be used with a feed tube 
112 of a comparably smaller diameter. In these instances, however, the 
inside diameter of the bearing 114 will be larger, and the radial 
thickness of the bearing 114 will be greater to ensure proper support and 
sealing around the feed tube 112. 
The apparatus 10 is used by feeding particulate material into the open top 
70 of the hopper 14 while simultaneously activating the vibrator 90 and 
the motor 120 for driving the screw 106. Vibrations generated by the 
vibrator 90 are transmitted through the mounting bracket 92 into the 
double-walled trough 12 and to the vicinity of the bottom end 72 of the 
hopper 14 and the baffle 68 in the trough 12. These vibrations are 
transmitted efficiently through the double walled trough 12 to ensure a 
continuous flow of particulate material on either side of the baffle 68 
and into the open-topped upper recess 32 in the trough 12. Particulates 
then flowing gravitationally toward the bottom wall 42 of the open-topped 
upper recess 32 in the trough 12 are carried by the screw 106 through the 
feed tube 112. The mounting bracket 92 has been found to be an efficient 
transmitter of the vibrations. Additionally, the plastic of both the 
trough 12 and the hopper 14 have been found to exhibit a quite operation 
due to the nature of the plastics, and due to the double walled 
configuration of the upper and lower recesses 32 and 48 of the trough 12. 
Additionally, the double walled configuration of the trough 12, combined 
with the outward flare of the outer end walls 24 and 26 near the screw 106 
provides effective support for both the feed tube and the drive shaft and 
their respective seals. 
While the invention has been described with respect to a preferred 
embodiment, it is apparent that various changes can be made without 
departing from the scope of the invention as defined by the appended 
claims.