Abstract:
Apparatus and method for controlling the distribution of product items over a manufacturing line, in particular, for controlling the distribution of potato slices across the width of a fryer in a commercial potato chip manufacturing process, includes a number of sensors for measuring the moisture content of potato chips exiting the frying and a controller for determining whether a moisture content variation state exists that should be corrected. A number of rotatable flume distributors are provided which are controlled by the controller in accordance with position adjustment values in a look-up table corresponding to detected moisture content variations. The flume distributors are then adjusted to modify the distribution of potato slices across the fryer to reduce or eliminate the variation in moisture content of the chips leaving the fryer.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an apparatus and method for controlling the distribution of product to manufacturing apparatus in a manufacturing process to improve the quality of the finished product. In particular, the invention relates to an apparatus and method for controlling the distribution of food slices, such as potato slices for potato chips, across a fryer in a manner that compensates for variation in the moisture content of slices exiting the fryer by correcting the distribution of slices being fed to the fryer across the width of the fryer to minimize variations in slice moisture content across the fryer. 
     2. Description of Relevant Art 
     Commercial production of potato chips typically involves a process wherein potato slices are continuously fed into a vat of hot oil, conveyed through the hot oil by suitable means such as paddles, conveyors and the like, and removed from the oil after an appropriate amount of time when the moisture content of the potato chips has been reduced to about 1.3% -1.4% by weight. 
     The fryer in such process is typically comprised of an elongated vat or tank for containing frying oil at a temperature of approximately 365° F. Oil supply inlets and oil return outlets are furnished in the tank to provide a circulating supply of hot oil for frying the potato slices. The potato slices are formed by feeding peeled raw potatoes into a number of centrifugal slicer heads, which slice the potatoes into generally uniform slices of appropriate thickness. The slices exiting the slicer heads are then fed to a number of flumes leading the slices to a conveyor belt on which they are passed into the fryer. 
     The positioning of the flumes typically is directed to achieve a generally even distribution of raw potato slices across the width of the fryer. However, varying conditions in the fryer such as, for example, changes in oil flow, oil temperature, potato slice movement, can cause uneven frying of potato slices, which may result in finished chips having relatively widely varying moisture content. Such variation in moisture content may lead to consumer dissatisfaction with perceived product freshness. 
     Additionally, during the manufacturing process it is necessary to periodically shut down individual slicers for the purpose of changing slicer heads as a routine maintenance procedure. In the prior art process, this has resulted in an interruption in chip production because of the need to stop the entire line while the slicer head is removed and replaced. This process typically involves halting the feeding of peeled potatoes to the slicers, waiting for the fed slices to clear out of the line, stopping the line, removing and replacing the slicer head(s), starting the feed of peeled potatoes to the slicers, and restarting the production line. The need to periodically change slicer heads presents a shortcoming in the production process that decreases efficiency and restricts product throughput. Consequently, there exists a need for improvement in the art to further improve the consistency of high product quality, and minimize production stoppages caused by the requirement for equipment maintenance. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus and method for improving the distribution of product in a manufacturing process so as to increase the consistency of product quality. According to another aspect, the present invention provides an apparatus and method which eliminates the disruption to a production line to carry out routine equipment maintenance. 
     In particular, the present invention provides apparatus for controlling the distribution profile of product items over a product manufacturing line, comprising means for measuring a physical characteristic parameter of individual product items at a predetermined location in the line, means for comparing a measured characteristic parameter with a predetermined value, and means for changing the distribution profile of product items over the manufacturing line as a function of the result of the comparison. 
     The present invention further provides, according to a further aspect, apparatus for controlling the distribution of potato slices across the width of a fryer in a commercial potato chip manufacturing line, comprising a plurality of slicer heads, each provided with a supply of potatoes and forming from the potatoes a plurality of substantially uniform potato slices, and discharging the potato slices at respective outlets thereof, a plurality of flumes operatively coupled to the outlets for transporting the slices to a conveyor, each of the flumes terminating in a distributor for placing slices on the conveyor at a specific location, wherein at least one of the distributors is controllably rotatable, a fryer for receiving from the conveyor potato slices to be fried and discharging potato chips produced from the slices at an exit thereof, a plurality of sensors in proximity to the fryer exit for detecting the moisture content of potato chips exiting the fryer as a function of location across the width of the fryer, and developing signals representative of the moisture content, a controller which receives the signals and compares the signals with a predetermined set of values to determine whether variations in moisture content exist among potato chips as a function of location across the width of the fryer, and a look-up table containing position adjustment values for the at least one controllably rotatable distributor as a function of moisture content variation states, the controller retrieving from the look-up table position adjustment values by inputting determined moisture content variation states and controlling the at least one controllably rotatable distributor to rotate to a position such that the distribution of potato slices on the conveyor is changed in a manner to reduce the moisture content variation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features, benefits and advantages of the present invention will become apparent from the following description of preferred embodiments thereof taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a schematic diagram of product manufacturing equipment according to a preferred embodiment of the present invention; 
     FIG. 2 is an elevational view of a rotatable flume according to a preferred embodiment of the present invention; 
     FIGS. 3A and 3B are diagrams illustrating possible orientations of the variable-angle rotatable flumes according to the present invention; 
     FIG. 4 is a flow diagram of an operation of a controller according to the present invention for adjusting the orientation of the slice flumes; 
     FIG. 5 is a first example of a Look-Up Table (LUT) containing flume adjustment positions according to moisture variation; 
     FIG. 6 is a second example of a Look-Up Table (LUT) containing flume adjustment positions according to moisture variation; and 
     FIG. 7 is a flow diagram of an operation of a controller according to the present invention for adjusting slice flume orientation during slicer head maintenance shutdown. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in relation to apparatus for producing potato chips for purposes of explanation. However, it will be apparent to those skilled in the art that the invention would be applicable to any distributed product manufacturing process in which uniform product characteristics are dependent upon distributed parameters during the manufacturing process. 
     In a commercial potato chip manufacturing process, a supply of raw peeled potatoes is fed to a plurality of centrifugal slicers  10   a - 10   d , which cut the potatoes into substantially uniformly shaped slices of substantially uniform thickness. Such slicers are well known in the art, see, e.g., U.S. Pat. No. 4,945,794, and therefore a description of their operation will not be provided here. 
     The raw potato slices  16  are conveyed from the slicers by a plurality of flumes  12   a - 12   d  to a washer belt  18 , where the raw slices may be washed, before being fed to fryer  20 , which contains a circulating supply of hot frying oil. The slices are loaded onto belt  18  by a plurality of flume distributor chutes  14   a - 14   d . The slices are conveyed through the fryer by paddles or a like mechanism (not shown) for a predetermined period of time, after which the resulting chips are removed from the fryer by a conveyor  22 , such as an endless belt. The chips are then passed by a plurality of moisture sensor heads  24   a - 24   c , which detect the moisture levels of chips divided by location on the belt into left ( 24   a ), center ( 24   b ) and right ( 24   c ). Such heads also are well known in the art, and are available from Scientific Industrial Development Corporation under the designation MM55. The sensor heads  24   a - 24   c  then convert the detected moisture levels into electrical signals and output the signals on signal lines  26   a - 26   c  to a Programmable Logic Controller (PLC)  28 . Based on the received moisture readings, the PLC  28  will adjust the orientation of rotatable flume chutes  14   b  and  14   c  to redistribute raw slices  16  across belt  18  to compensate and correct for variations in moisture levels of chips exiting the fryer according to left, center and right designations. Such variations may be caused by varying conditions such as oil flow through the fryer, oil temperature gradients within the fryer, slice migration, as well as other phenomena. 
     According to a preferred mode of operation as illustrated in FIG. 4, the PLC  28  collects the moisture readings at step S 40  and averages left, center and right readings over a predetermined period of time at step S 41 . At step S 42 , the averaged readings are compared with preset variation limits, to determine whether significant moisture level variations are present. For example, as shown in FIGS. 5 and 6, moisture levels within an acceptable range would be classified as “O” for “on target;” levels above the range would be classified as “H” for “high;” and levels below the range would be classified as “L” for “low.” At step S 43 , the comparison results are inputted to Look-up Tables (LUTs) such as  50  in FIG. 5 or  60  in FIG. 6, to determine whether adjustment of rotatable flume chutes  14   b  and/or  14   c  is needed. The adjustments programmed into the LUTs are calculated by experimentation through measurement and observation over a sufficient period of time. It is noted that in the preferred embodiment, outer flume chutes  14   a  and  14   d  are stationary, and are oriented so that slices will be positioned just inside the outer edges of belt  18 , while inner flume chutes  14   b  and  14   c  are rotatable. FIG. 2 is a side elevational view of chute  14   b . As shown, a motor  141  drives a pulley or belt  142  which rotates a column  143  attached to the bottom of chute  14   b.    
     The flume chutes are rotated with the purpose of minimizing moisture level variations of chips exiting the fryer. The possible arc of rotation of the inside chutes is set between a position that places the slices in the middle of belt  18  and a position that places slices just adjacent to the corresponding outside flume chute. Proximity sensors (not shown) detect when a chute is either at its outside limit, or in a zone where collision with the other controlled flume chute is possible. Limit switches (also not shown) are provided within the motor housing to determine when the motors have reached their rotation limit. The range of positions of each controllable chute is calibrated to a range of zero to 100, with 50 denoting the center position, zero denoting a fully counterclockwise (CCW) position, and 100 denoting a fully clockwise (CW) position. Depending on the moisture readings, a chute may be rotated by a large adjustment, a small adjustment, or no change. The degree of rotation corresponding to “large” and “small” may be set appropriately by trial and error. FIGS. 5 and 6 give Ad examples of adjustments based on the calculated moisture level readings. For example, as shown in FIG. 5, where the right side of the fryer has a “low” moisture reading, and the center and left sides are within target level, chute  14   c  will be moved counterclockwise by a “large” amount, while chute  14   b  will be moved counterclockwise by a “small” amount. This adjustment has the effect of redistributing the slices across the fryer so that more slices are fed to the right side of the fryer. This is shown in FIG.  3 A. 
     As shown in FIG. 3B, when the readings indicate that the moisture level of chips at the left and right sides of the fryer are high, while the chips at the center of the fryer are within target range, chute  14   c  will be moved in a clockwise direction by a “small” increment, while chute  14   b  will be moved in a counterclockwise direction by a “small” increment. This has the effect of reducing the amount of chips fed to the left and right sides of the fryer to bring the moisture levels down to target range. 
     The necessary adjustments are read from the LUTs by the PLC controller  28 , and are converted into actuator signals inputted to the actuator motors  141  through signal lines  30   b  and  30   c.    
     FIG. 7 explains operation of the PLC when a slicer needs to be shut down, such as for changing of the slicer head. At step S 70 , the PLC continuously monitors whether a slicer head has been shut off. When a shut off is detected, the present flume positions are stored in a memory at step S 71 . At step S 72 , the controllable flume chutes are rotated to positions depending on the slicer head which has been shut off, such that an even distribution of slices across the fryer will be maintained. 
     The PLC then continuously monitors whether the slicer head has been turned back on at step S 73 . Once the PLC determines that the slicer has been placed back in service, the stored flume positions are retrieved from memory, and the flumes are restored to their previous positions at step S 74 . 
     According to the invention, the system may also include a manual mode wherein the flume positions may be adjusted manually. The system further provides for “home” positions at which the controllable flumes will be oriented at line start-up. The “home” positions are predetermined positions which represent optimal starting points for achieving minimum moisture level variations across the fryer at start-up. 
     Additionally, flip-up gates are provided at the inlets to the slicer heads, so that raw potato supply may be stopped to a specific slicer when it is necessary to shut down for slicer head replacement. 
     While the present invention and the embodiments presented herein have been set forth and described in detail for the purposes of making a full and complete disclosure of the subject matter thereof, the disclosure herein presented is not intended to be limiting in any way with respect to the scope of this invention as the same is set forth in the appended claims.