Abstract:
Complexity of construction of a vibratory feeder is minimized in an assembly including a base ( 10; 108, 114, 116, 118 ) and an elongated, generally horizontal feeder ( 14; 100 ) spaced from the base ( 10; 108, 114, 116, 118 ). A rotatably mounted eccentric ( 32; 126 ) is journaled on the feeder ( 14; 100 ) and is operable, when rotated, to impart vibration to the feeding surface ( 20; 104 ) of the feeder ( 14; 100 ). The feeder ( 14; 100 ) is interconnected to the base ( 10; 108, 114, 116, 118 ) by an interconnection that consists essentially of springs ( 60; 130 ) having first ends ( 62 ) connected to the feeder and opposite ends ( 64 ) connected to the base ( 10; 108, 114, 116, 118 ) while being located on a generally horizontal axis.

Description:
FIELD OF THE INVENTION 
     This invention relates to vibratory feeders or conveyors, and more particularly, to a reversible or two-way vibratory feeder. 
     BACKGROUND OF THE INVENTION 
     Two-way vibratory feeders or conveyors have substantial applications in a variety of fields. One typical application is in foundry operations. For example, castings may be delivered to the feeder at a location intermediate its ends and then the feeder is energized to feed the castings to one end or the other depending upon where it is desired to locate the castings. Typical two-way feeders include an elongated bed with an upwardly facing, generally horizontal conveying or feeding surface which terminates at opposite ends. The bed is supported on isolation springs adjacent the ends which in turn serve to mount the bed above the underlying terrain such as a floor in a factory building or the like. 
     Two motor and weight assemblies, which form vibration inducing systems, are secured to the bed generally centrally thereof. Each will typically include a squirrel cage motor having a rotary output shaft to which is secured in an eccentrically mounted weight. Springs in the form of plastic or fiberglass slats connect each of the motors to the bed. 
     Each of the vibration inducing systems is canted at approximately 45° to the bed but in directions oppositely of one another. When it is desired to feed in one direction, one of the vibration inducing systems is energized while the other remains quiescent if the opposite direction of feeding is required, then the other vibration inducing system is energized while the first remains quiescent. 
     In many applications, it is not unusual that there is a considerable disparity between the amount of use of the two vibration inducing systems. If one system is used to the substantial exclusion of the other, so called “false Brinnelling” of the motor bearings on the unused system will occur as a result of the vibration imparted to the bed by the first system. Lubricant may be squeezed out of the bearings as a result and when the system is finally energized, it may fail relatively quickly as a result of bearing failure. 
     Moreover, in foundry applications, the bed typically will be formed of metal to stand up to the continued pounding of castings. In a prior art system such as described, vertical acceleration of the feeding surface during operation will typically exceed that of gravity. As a result, after the surface has reached its highest point of movement in a cycle of vibration, it will then be accelerated downwardly more rapidly than a casting or the like conveyed by the feeder in responding to gravity. The casting will be temporarily suspended above the conveying surface but will eventually collide with it as movement of the surface begins to reverse while the casting is being moved downwardly under the influence of gravity. The result is a noise producing impact of the casting upon the metal of which the conveying surface is formed and the noise level will typically be undesirably high. 
     It will also be appreciated that the provision of two vibration inducing systems in a single feeder or conveyor when only one is used at any given time adds considerably to the cost of the apparatus. 
     The present invention is directed to overcoming one or more of the above problems. 
     SUMMARY OF THE INVENTION 
     It is the principal object of the invention to provide a new and improved two-way or reversible vibratory feeder or conveyor. More specifically, it is an object of the invention to provide a vibratory feeder wherein the problem of premature bearing failure is eliminated, the noise produced during operation is substantially reduced, and the cost of construction is reduced by the elimination of many components heretofore believed required in a construction of such a vibratory feeder. 
     It is also a principal object of the invention to provide a new and improved vibratory feeder of extremely simplified construction to thereby reduce initial cost as well as ongoing maintenance requirements. 
     An exemplary embodiment of the invention achieves the foregoing objects in a vibratory feeder that includes a base. Means define an elongated, generally horizonal feeding surface which is spaced from the base and a rotatably mounted eccentric is journaled on the surface defining means and operable, when rotated, to impart vibration to the surface. An interconnection mounts the surface defining means to the base and consists essentially of a resilient element having one end connected to the surface defining means and an opposite end connected to the base. The resilient element has its ends on a generally horizonal axis and is of sufficient stiffness to prevent the axis from shifting from a generally horizontal position. 
     In a preferred embodiment, there is additionally included a reversible, rotary output motor for driving the eccentric. The motor, for one direction of rotation causes feeding in one direction on the surface defining means and for the other direction of rotation, causes feeding in the opposite direction on the surface defining means. 
     In a preferred embodiment, the surface defining means and the eccentric have a combined center of gravity and the generally horizontal axis extends through the combined surface of gravity. 
     In a preferred embodiment, there are at least two of the resilient elements, one on each side of the eccentric. 
     Preferably, the resilient elements are coil springs. 
     In another facet, the invention provides a vibratory feeder that includes a base along with means defining an elongated, generally horizontal feeding surface spaced from the base and a rotatably mounted eccentric journaled on the surface defining means and operable, when rotated, to impart vibration to the surface. The feeder further includes a pair of spaced, resilient elements located on a generally horizontal axis and connecting the surface defining means in the base. The resilient elements are of sufficient stiffness as to maintain a desired spacing between the surface defining means and constitute the sole means interconnecting the base and the surface defining means. 
     Preferably, the eccentric comprises a weight mounted on the output shaft of a reversible motor. 
     In a preferred embodiment, each resilient element comprises at least two horizontally elongated, coil springs. 
     By still another definition, an exemplary embodiment of the invention is a two-way vibratory feeder that includes a base, a horizontally elongated feeder having an upwardly facing feeding surface and opposed ends, and a reversible motor having a rotary output shaft and generally centrally mounted between the ends of the feeder with the output shaft being generally horizonal and transverse to the direction of elongation of the feeder. At least one weight is eccentrically mounted on the output shaft and is rotatable therewith for either direction of rotation thereof. A support assembly is provided for connecting the feeder to the base and consists essentially of two spaced horizontally disposed coil springs, one on each side of the output shaft, each such spring having two ends with one end mounted on the base and the other end mounted to the feeder. 
     According to one embodiment, the feeder, the motor and the weight have a combined center of gravity and the springs are located on a horizontal axis that extends through the center of gravity. Adjusting weights are included on the feeder to assure passage of the horizontal axis through the combined center of gravity. 
     Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings. 
     In a highly preferred embodiment, the feeder includes at least one elongated, generally horizontal balance bar as part of the base and which extends generally parallel to the feeding surface. The resilient element or elements are connected between the balance bar and the feeding surface. The balance bar in turn is supported above on underlying surface by generally vertical isolation springs. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation of a two-way vibratory feeder made according to the invention; 
     FIG. 2 is vertical section taken approximately along the line  2 — 2  of FIG. 1; 
     FIG. 3 is a sectional view taken approximately along the line  3 — 3  of FIG. 1; 
     FIG. 4 is a graph illustrating certain operational characteristics of an embodiment of the invention as they relate to the spring rates of resilient elements employed in the construction of the invention; 
     FIG. 5 is a side elevation of a modified embodiment of the invention; 
     FIG. 6 is a vertical section taken approximately along the line  6 — 6  of FIG. 5; and 
     FIG. 7 is a vertical section taken approximately along the line  7 — 7  of FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An exemplary embodiment of the invention is illustrated in FIGS. 1-3 and is seen to include a base  10  in the form of an inverted channel that is mounted to the underlying terrain  12  which may be the floor of a building or the like. A feeder, generally designated  14 , is supported above the base  10  as will be seen. However, it is to be understood that in some installations, it may be desirable that the base  10  be located above the feeder  14 . 
     In the illustrated embodiment, the feeder  14  is in the form of a simple I-beam turned on its side so that its top and bottom plates  16  form vertical, confining side walls for its web  18 . The upper surface  20  of the web  18  serves as a conveying or feeding surface. 
     Centrally of the feeder  14  is a vibratory exciter, generally designated  22 . The same includes a reversible, variable speed electric motor  24  having a rotary output shaft  26 . The motor  24  is secured to a plate  28  which in turn is secured as by welding to the plates  16  of the I-beam defining the feeder  14 . Threaded fasteners and bolts, generally designated  30 , may be used for the purpose. 
     The rotary shaft  26 , on both ends thereof (only one of which is seen), mounts eccentric weights  32 . As seen in FIG. 3, the eccentric weights  32  may be contained within housings  34  on both sides of the motor  24 . 
     As noted previously, the motor  24  is preferably a reversible, variable speed motor. By reversing the direction of the rotation of the output shaft  26 , the direction of conveying along the surface  20  may be reversed. Similarly, by varying the speed of the motor  20 , the rate of conveying can be adjusted as well. Generally, however, it will be desirable to keep the rate of rotation of the output shaft  26  within a range for purposes to be seen. 
     In a usual case, the motor  24  will also be fitted with an electronic brake of known configuration so that when it is de-energized, rotation of the shaft  26  may be stopped rather abruptly rather than allowing the shaft  26  to coast for several seconds or even longer. 
     The base includes upstanding pedestals  40  and  42  located on opposite sides of the exciter  22 . Spaced axially outwardly from the pedestals  40  and  42  toward the ends  44  and  46  of the feeder  14  are downwardly directed projections  48  and  50 . The projections are secured to the underside of the feeder  14  and have vertical surfaces  52  and  54  facing corresponding vertical surfaces  56  and  58  on the pedestals  40  and  42 . Horizontally elongated metallic coil springs  60  are located between the surfaces  52  and  56  and the surfaces  54  and  58  and are fastened thereto at their respective ends  62  and  64  as by bolts or the like. In some instances, conventional air bags may be used in lieu of the springs  60 . 
     As shown in FIG. 2, the springs on each side of the motor  22  may be paired. For that matter, depending upon the size of the feeder  14 , more than two springs may be included in any given spring assembly or resilient element defined thereby. 
     The springs  60  have two different springs rates. A first is the vertical spring rate which is the spring rate that comes into play when one tries to axially compress or extend the springs, i.e., bring the ends  62  and  64  toward or away from one another. The second is known as the horizontal spring rate which is the spring rate that comes into play when one tries to bend one or both ends of the spring relative to the spring longitudinal axis. In a preferred embodiment, the springs  60  have a vertical spring rate of 3,200 lbs. per inch and a horizontal spring rate of 1,237 lbs. per inch. The springs  60  are sufficiently stiff as to support the feeder  14 . That is, the springs  60  will not sag to depart substantially from their alignment on a horizontal axis. 
     Those skilled in the art will recognize that the feeder  14  in the exciter  22  and its various components have a combined center of gravity (CG). It is found to be desirable that the horizontal axis on which the springs  60  are disposed pass through the center of gravity (CG). Thus, the invention contemplates the mounting of plate-like weights  70  to both ends  44  and  46  of the feeder  14  to adjust the location of the center of gravity (CG) so that it is located in the plane defined by the horizontal axis of the springs  60 . 
     FIG. 4 illustrates a plot of amplitude versus frequency (the latter in RPM) of spring movement according to both the horizontal spring rate curve and the vertical spring rate curve. The designation “fnh” illustrates the natural horizontal frequency of the system while the designation “fnv” illustrates the natural vertical frequency of the system. 
     It is preferred to operate at a frequency of about 90-95% of the vertical natural frequency. Operation in this range assures proper conveying movement while avoiding overstressing of the springs  60 . 
     In operation, the springs  60  act to amplify the vibration induced upon the feeder  14  by the exciter  22 . The locus of a point on the feeder  14  is a very much flattened oval pattern which is highly horizontally elongated. This is highly desirable because it minimizes or eliminates separation between castings on the feeding surface  20  and the feeding surface to eliminate the noise of impact of the castings thereon. 
     The springs  60  also act as isolation springs when the frequency of operation is equal to 1.4 or more of the horizontal natural frequency. In a preferred embodiment, it is preferred that the frequency of operation “f” is approximately three times the natural horizontal frequency. 
     It will be appreciated from FIG. 4, keeping in mind that the springs  60  are disposed horizontally so that the vertical rate curve applies to horizontal movement and the horizontal rate curve applies to vertical movement, that vertical displacement of the surface  20  is minimal while substantial horizontal displacement occurs to assure adequate conveying with minimal noise generation as mentioned previously. This embodiment of the invention eliminates the need for isolation springs separate from amplification springs as well as springs interconnecting one or more exciters to the feeder itself. The vibratory feeder of the invention is a picture of simplicity, requiring but a single exciter, at least one spring assembly, a base and a feeder having a feeding surface. Thus, it will be readily appreciated by those skilled in the art that the objects of the invention have in fact been accomplished. 
     A modified and highly preferred embodiment is illustrated in FIGS. 5-7 inclusive. A trough, generally designated  100 , defines a generally horizontal conveying surface. The trough  100  includes upstanding, spaced sidewalls  102  connected by a bottom wall  104  upon which material  106  to be conveyed is supported. The trough  100  is flanked by two horizontally elongated balance bars  108 , one adjacent each of the upstanding sidewalls  102 . At the ends  110 ,  112 , of each balance bar  108 , a depending pedestal  114  is mounted. The pedestals  114  are, in turn, mounted on the upper ends of vertically oriented coil springs  116  which, in turn, are supported on pedestals  118  secured to the underlying surface  120 . Of course, it will be recognized that the mounting thus provided could be as a result of a suspension system if desired. 
     A bi-directional, that is, reversible, electric motor  122  is mounted to the underside of the trough  100  at a central location along the length of the trough  100 . The motor  122  has a horizontally directed output shaft  124  upon which an eccentric weight  126  is mounted. In a preferred embodiment, the output shaft  124  extends to both sides of the body of the motor  122  and each end of the shaft  124  mounts in an eccentric weight  126 . 
     Inwardly of the pedestals  114  mounting the balance bars  108 , the undersurface of the trough  100  mounts downwardly extending projections  128 . Coil springs  130 , which may be the same as the coil springs  60  in the first embodiment, extend between the projections  128  and an I-beam  132  which interconnects the pedestals  114  below the bottom surface  104  of the trough  100 . 
     As a result of this construction, a two-way vibratory feeder similar to that described in connection with FIGS. 1-4 is provided. In addition, the embodiment shown in FIGS. 5-7 possesses a further advantage in that the springs  116  provide isolation to prevent any substantial vibration as a result of operation of the conveyor from being transmitted to the underlying terrain  120 . Moreover, and most importantly, the balance beams  108  serve to counterbalance horizontal vibratory forces induced as a result of operation of the motor  122 . In this respect, the mass of the balance bars  108  is generally chosen to equal the mass of the trough  100  and the projections  128  and an expected amount of material  106  on the surface  104 . In operation, because horizontal movement of the trough  100  in one direction will tend to compress the coil springs  130 , the resulting reaction during operation will be to cause the balance beams  108  to move in the opposite direction of the trough  100 , thus serving as a counterbalance to the vibration induced in the trough  100 &#39;s operation of the motor  122  and the eccentric weight  26 . As a result, very little vibration in the horizontal direction is present at the isolation springs  116  and that which is present is effectively isolated by the springs  116 . Thus, the embodiment of FIGS. 5-7 is capable of providing conveying or feeding motion in either of two directions, depending upon the direction of rotation of the shaft  124  while at the same time, providing a counterbalance of such force within the base for the apparatus to prevent the transmission of the vibratory force to the underlying terrain. This presents a substantial advantage in terms of reducing the vibration imparted to the environment while retaining all of the advantages of the embodiment illustrated in FIGS. 1-4, as enumerated above.