Abstract:
A case erector receives a horizontal stack of flattened cases of varying case size as input, and automatically adjusts to output a stream of formed cubical cases, each case having a rectangular cross-section and a closed bottom end. The case erector includes a sensor for determining the case size signal from the sensor, and plural adjustment devices, responsive to the controller to automatically adjust the case erector to erect the particular case size. The case erector includes a case input magazine that can receive cases of one size or cases of varying size. The magazine includes a rack having a V-shaped supporting surface. The V-shaped supporting surface spans approximately 90° and is bisected by a vertical plane. The V-shaped supporting surface is tilted at an angle downwardly along a direction of case propagation feed into the case forming section of the case erector.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    The invention relates to machines for erecting cases. Particularly, the invention relates to machines which automate the manipulation of flattened cases so as to be rectangular in cross-section, and the manipulation and securement of flaps on one end of the case to form a closed end.  
         BACKGROUND OF THE INVENTION  
         [0002]    Conventional cardboard or corrugated board cases or cartons of the four-flap style are typically shipped to packaging companies in a flattened state. The flattened cases are provided with four fold lines to allow manipulation of the case from the flattened state into a rectangular tube. The four flaps at the bottom of the tube are respectively separated by four slots that are respectively colinear with the four fold lines. After the flattened case is formed into a rectangular tube, the four flaps on at least the bottom end of the case are sequentially folded over forming a closed end and secured with a strip of tape, to form a cubical case with an open top.  
           [0003]    Case erector machines for setting-up cubical cases from flattened cases are generally known, such as disclosed in U.S. Pat. Nos. 4,067,172; 4,579,551; 5,112,288; and 5,689,931.  
           [0004]    U.S. Pat. No. 4,067,172 discloses a typical system wherein a vertical stack of flattened cases is held in a case magazine, with the cases in a horizontal orientation. The magazine is adjustable to hold a preselected case size within a range of case sizes. The cases are dispensed from the magazine wherein the lowest case is pulled downwardly from the magazine. The cases are each transformed from a flattened case to a rectangular cross-section case by a horizontally moving set-up finger.  
           [0005]    At a side open end of the case, a rotatable arm and a fixed cam close the vertical flaps, and a stationery cam folds the bottom flap. The top flap is temporarily held open. The flaps of the opposite open end of the case are folded closed in the same manner after the case is filled with a product. The top flaps of both ends are folded and closed after adhesive is applied to bottom surfaces thereof.  
           [0006]    Another type of case erector, similar to that disclosed in U.S. Pat. No. 4,579,151, includes a magazine arranged to hold vertically oriented, and horizontally stacked flattened cases, the stack tilted toward a case feeding direction, with bottom edges of the flattened cases supported horizontally. A transport uses suction cups to transport a leading case of the flattened cases to a longitudinal transport. The leading case is manipulated into a rectangular tube, and the bottom flaps of the rectangular tube are folded from below to create a closed bottom end, by use of moving plates and stationary ploughs. A taping mechanism within the longitudinal transport path is used to secure the bottom end.  
           [0007]    These type case erectors typically require substantial manual adjustments for changing case size. The adjustments can be time consuming and prone to errors.  
           [0008]    The present inventors have recognized the desirability of providing a case or case-erecting machine that minimizes the need to manually adjust a case magazine to accommodate different size cases. The present inventors have recognized the desirability of providing a case erector which can receive a stream of flattened cases of mixed sizes, and outputs a stream of corresponding rectangular cross-section cases having a closed and secured bottom end.  
           [0009]    The present inventors have recognized the desirability to remove the human element when changing over the machine from one size flattened case to another.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention provides a case erector that is adapted to receive a horizontal stack of flattened cases of varying case size as input, and automatically adjusts to output a stream of formed cubical cases, each case having a rectangular cross-section and a closed bottom end. The case erector includes a sensor for determining the case size, a controller that receives a case size signal from the sensor, and plural adjustment devices, responsive to the controller to automatically adjust the case erector to erect the particular case size.  
           [0011]    The case erector of the present invention includes a case magazine that can receive cases of one size or cases of varying size. The case magazine is mounted adjacent a case forming section of the case erector to feed cases into the case forming section. The magazine includes a rack having a V-shaped cross-section defined by two supporting surfaces. The supporting surfaces span an angle of approximately 90° and are tilted obliquely from a vertical plane. The supporting surfaces define a line of intersection that is tilted at an angle downwardly along a direction of case propagation into the case forming section of the case erector.  
           [0012]    The cases are held behind retaining lips on a front face of the supporting surfaces. One or more pneumatically operated pushers are arranged adjacent to one of the supporting surfaces and are selectively activated to push a stack-leading case to a release position, clearing the retaining lips the one supporting surface. A case transfer arm engages the leading case and displaces the case from the retaining lip of the respective other supporting surface and places the case in a staging position. At the staging position, a sensor determines the position of a slot which defines the length of the end flaps, which in turn defines the case size. Using this sensed information, a plurality of adjustable manipulation or transport devices on the case erector can be automatically adjusted for a particular case size. This case size sensing routine can be undertaken for each case moved by the transfer arm from the front face of the supporting surfaces to the staging position.  
           [0013]    The sensor can be an optical sensor mounted on a carriage. The carriage is driven along a transport rod in a direction parallel to a predominant face of the case at the staging position. The carriage is driven from a home position to a position where a case slot, located between a side bottom flap and a rear bottom flap of the flattened case, is sensed by the optical sensor. At that point, the carriage position and the case size is calculated by the controller.  
           [0014]    The controller advantageously provides an automatic adjustment of a substantial portion of, or all of, the necessary clearances and movements of the case erector that are necessary when changing case size.  
           [0015]    Also advantageous is the fact that the magazine of the present invention accepts cases of varying sizes without the need to adjust a support on the magazine to hold the cases, due to the orientation and configuration of the V-shaped supporting surface of the magazine.  
           [0016]    Numerous other advantages and features of the present invention will be become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view of a case erector apparatus of the invention;  
         [0018]    [0018]FIG. 2 is an elevational view of a flattened case;  
         [0019]    [0019]FIG. 3 is a bottom perspective view of the case of FIG. 2 set up into a cubical case with a bottom end closed and taped;  
         [0020]    [0020]FIG. 4 is a schematic plan view of a case erector machine of the invention;  
         [0021]    [0021]FIG. 5 is a sectional view taken generally along line  5 - 5  of FIG. 4;  
         [0022]    [0022]FIG. 6 is a sectional view taken generally along line  6 - 6  of FIG. 4;  
         [0023]    [0023]FIG. 7 is an end view taken generally along line  7 - 7  of FIG. 6;  
         [0024]    [0024]FIG. 8 is an enlarged fragmentary sectional view taken generally along line  8 - 8  of FIG. 1;  
         [0025]    [0025]FIG. 9 is an enlarged fragmentary perspective view of a staging transport taken from FIG. 1;  
         [0026]    [0026]FIG. 10 is an enlarged fragmentary perspective view of a position sensor taken from FIG. 1;  
         [0027]    [0027]FIG. 11 is an enlarged fragmentary perspective view taken of the position sensor from FIG. 10;  
         [0028]    [0028]FIG. 12 is a schematical exploded perspective view of the progressive formation of the case shown in FIG. 2 into the case shown in FIG. 3;  
         [0029]    [0029]FIG. 13 is a sectional view taken generally along lines  13 - 13  of FIG. 12;  
         [0030]    [0030]FIG. 14 is a sectional view taken generally along lines  14 - 14  of FIG. 12; and  
         [0031]    [0031]FIG. 15 is a block flow diagram of a control system of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, a specific embodiment thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustrated.  
         [0033]    [0033]FIGS. 1 and 4 illustrate a case erector apparatus  20  of the invention. The apparatus  20  includes a flattened case input station  24 , and a case forming apparatus  25 . The case forming apparatus  25  includes a case staging transport  26 , a lateral case transport  28 , a longitudinal case transport  32 , and a longitudinal case conveyor  36 . The transports  26 ,  28 ,  32  and the conveyor  36  are all signal-connected and controlled by a controller  38 .  
         [0034]    The input station  24  includes a magazine  40  which carries a plurality of flattened cases  44  (as shown in FIGS. 4 and 5), vertically oriented and horizontally stacked, and of varying sizes. The case sizes can vary randomly or case sizes can be arranged in groups, the size changing only after the group is depleted.  
         [0035]    The magazine  40  can be vertically adjusted by a servomotor  46  which drives a threaded rod connected between a floor supported frame  48  and a magazine supporting frame  49 . The magazine  40  can be horizontally adjusted in longitudinal position by use of a servomotor and an interposed carriage between the floor and the floor supported frame  48 , shown in FIG. 7.  
         [0036]    The case staging transport  26  includes a pivoting transfer arm  50  (shown in FIGS. 5, 6 and  9 ) having a suction cup  52  which engages a leading flattened case  44   a  within the magazine  40 . The arm  50  moves the case  44   a  out of the magazine  40  and onto a staging ledge or platform  56 . A sensor  60  (shown in FIGS. 10 and 11), such as an optical sensor, is movable horizontally along the ledge  56 , facing the case  44   a.  The sensor  60  is signal connected to the controller  38 . The sensor  60  is operable to determine the size of each successive leading case  44   a  as described below.  
         [0037]    The lateral transport  28  includes a conveyor  68  driven by a servomotor  70 , which laterally moves a carriage  71 . The carriage  71  carries an extending arm  72 . The extending arm  72  carries a plurality of suction cups  76 . In operation, the conveyor  68  moves the extending arm  72  and suction cups  76  from a retracted position shown to a position (shown in phantom in FIG. 4) adjacent to the first case  44   a  on the staging platform  56 . The conveyor  68  moves the suction cups  76  to engage the case  44   a  on the ledge  56 . The conveyor  68  then moves the suction cups  76  along with the case  44   a  from right to left in FIG. 4. A portion of the flattened case  44   a  is pressed by a stationary plough  80  to open the flattened case to a rectangular cross-section or rectangular tube (shown in phantom in FIG. 4), as the case is moved from right to left. The conveyor  68  retracts to position the case  44   a  in a “handoff” position along a longitudinal centerline CL of the case forming apparatus  25 .  
         [0038]    The case erector apparatus  20  includes various components which are well known to one of skill in the art. For example, each suction cup comprises a resilient cup mounted to a tubular housing having a through channel open into a central opening of the suction cup. The housing includes a suction inlet port such that a vacuum can be drawn through the suction cup and through the housing. Vacuum for the suction cup is typically created by a pneumatically powered vacuum pump. The suction cup can engage and hold, by suction pressure, the case  44   a.    
         [0039]    Pneumatic cylinders are also described which typically comprise a cylinder body having inlet outlet ports at opposite ends of the body. A rod passes longitudinally through end seals of the body and a piston is fixed to the rod within the body. Depending on the differential pneumatic pressure applied to the ports, the piston is forced to slide within the body in a selected direction.  
         [0040]    The longitudinal transport  32  includes a longitudinal conveyor  84  driven by a servomotor  85 , and suction cups  86  carried by the conveyor  84 . The transport  32  also includes a controllably pivotable plate  88  which pivots upward to close a rear flap of the case  44   a.  A pneumatic cylinder  89  (shown schematically in FIG. 1) expands and contracts to control movement of the plate  88 . The conveyor  84  moves longitudinally to engage the suction cups  86  to the case  44   a  at the handoff position and continues longitudinally to position the case a sufficient distance to be engaged and transported by the conveyor  36 .  
         [0041]    The conveyor  36  includes side conveyor belts  102 ,  104  which are spaced apart by a precise distance to grip the case  44 a between the belts. A servomotor  106  drives parallel threaded rods  107   a,    107   b  via a chain  107   c.  The threaded rods  107   a,    107   b  are threadingly engaged to moveable base members  102   a,    104   a  of the belts  102 ,  104 . By turning the servomotor  106  in a selected direction by a selected amount, a precise spacing of the belts  102 ,  104  is achieved. The belts  102 ,  104  are circulated in opposite directions to transport the case along the conveyor  36 . Within the area of the conveyor  36  are a stationary center plough  108  for closing the front flap of the moving case, and stationary side flap ploughs  114 ,  116  for progressively closing side flaps of the moving case  44   a.  A taping mechanism  124  (shown schematically) is located downstream of the ploughs  108 ,  114 ,  116  to secure the bottom of the case  44   a.  The taping mechanism  124  can be a type disclosed, for example, in U.S. Pat. Nos. 4,640,731 or 4,061,526.  
         [0042]    [0042]FIGS. 2 and 3 illustrates a flattened case  44  and a formed cubical case  44 . FIGS.  12 - 14  illustrate in step fashion the forming of the cubical case  44  from the flattened case  44 . The case  44  is preferably composed of cardboard or corrugated board. The case  44  includes a side wall  126  and an end wall  127  separated by a fold line  126   a  on the facing predominant side. The case  44  includes a reverse mirror image side wall  128  and end wall  129 , separated by a fold line  128   a,  on the reverse predominant side. Below the wall  127  is an end flap  131 . Below the sidewall  126  is a side flap  132 . Reverse mirror image front flap  133  and side flap  135  are also provided beneath the side wall  128  and end wall  129 . Fold lines  127   a,    129   a  are provided between the predominant side and the reverse predominant side. Slots  136 ,  137 ,  138 ,  139 , colinear with respective fold lines, are provided between the respective flaps  131 ,  132 ,  133 ,  135 .  
         [0043]    A top flap arrangement  139  is also provided. The top flap arrangement would be closed by a mechanism (not shown) after a product is placed into the case.  
         [0044]    [0044]FIGS. 5 and 6 illustrates the magazine  40  comprising a rack having a V-shaped cross section forming a 90° angle and preferably bisected by a vertical plane. The rack comprises first and second supporting surfaces  142 ,  144 . The supporting surfaces are defined by a plurality of spaced rails  145  (as shown in FIG. 1). The supporting surfaces  142 ,  144  define a line of intersection that is inclined at an angle of about 20° from the ledge  56 , rising in a rearward direction (into the page of FIG. 5). Retaining lips  148 ,  149  are arranged along front edges of the supporting surfaces  142 ,  144 , respectively. The lips  148 ,  149  retain the first case  44   a,  and cases behind the first case, in the magazine  40 .  
         [0045]    A first pneumatically operated pusher  150  and a second pneumatically operated pusher  152  are arranged along an edge of the second supporting surface  144  and are operable to lift an edge  44   b  of the case  44   a  from the remaining cases  44  and above the lips  149 .  
         [0046]    The pivot arm  50  (shown and explained in detail below with respect to FIG. 9) is pivotally connected at a first joint  154  to rotate about an axis parallel to the longitudinal center line CL and is pivotally connected at a second joint  158  to rotate about an axis parallel to the lateral direction, the lateral direction being horizontal and perpendicular to the longitudinal direction.  
         [0047]    A first pneumatic cylinder  162  controls rotation about the first joint  154  and a second pneumatic cylinder  164  controls rotation about the second joint  158 . The rotation about the second joint  158  allows the arm  50  to rotate to position the suction cup  52  facing the flattened case  44   a.  The arm  50  includes a third joint  159  at the suction cup  52  to allow the cup axis to remain perpendicular to the flattened case  44   a.    
         [0048]    Rotation about the first joint  154  allows the suction cup  52  to be rotated toward and away from the flattened case  44   a  to engage and then withdraw the flattened case  44   a  from the magazine  40 . The arm  50  can then be further rotated about the second joint  158  to place the leading flattened case  44   a  flushly onto the ledge  56 .  
         [0049]    The sensor  60  includes a carriage  159 , preferably in the form of a pneumatically translated rodless cylinder, which is moveable on a transport rod  166 . A guide rail  168  is located above the transport rail. The carriage includes a bearing  167  slideable along the guide rail  168 . The bearing  167  and guide rail  168  structurally act to ensure verticality of the sensor  60 . The sensor  60  is moved via the carriage  159  along the transport rod  166  from a home position  169  and issues a signal to the controller  38  when the case slot  136  is sensed by the sensor  60 . The movement of the sensor  60  from start to the position where the slot  136  is sensed is timed by the controller  38  to determine a distance traveled by the sensor and hence the position of the slot, given the known acceleration and speed of the carriage. The location of the case slot  136  defines the case size. The slot location information is used by the controller  38  to make machine adjustments as described below.  
         [0050]    From the ledge  56 , the lateral transport suction cups  76  engage the case  44   a.  The suction cup  52  is then disengaged, and the arm  50  is rotated about the second joint  158  to a position of noninterference with movement of the case  44   a  during withdrawal by the conveyor  68 .  
         [0051]    [0051]FIG. 7 illustrates a magazine  40  supported on a magazine carriage  210 . The magazine carriage  210  is slidably supported on rollers or bearings  216 . The bearings  216  are supported on one or more horizontal members  236  of the frame  49 .  
         [0052]    The frame  49  includes external pipe columns  220 ,  222  which slidably receive internal pipe columns  230 ,  232  of the frame  48 . The internal pipe columns  230 ,  232  are supported at base ends  230   a,    232   a  thereof on the floor or on a frame of the apparatus  25 .  
         [0053]    The vertical adjustment servomotor  46  drives a threaded rod  240  which threadingly engages a top member  242  of the frame  248 . By turning the threaded rod  240  with the servomotor  46  the frame  49  is drawn toward or retracted away from the frame  48  to set the vertical position of the magazine  40 . A horizontal adjustment servomotor  248  drives a threaded rod  252  which is threadingly engaged to a member  254  of the carriage  210 . By turning the motor  248  in a selected direction, the magazine carriage  210  is moved horizontally (left or right) on the frame  49 .  
         [0054]    Thus, by selectively operating the servomotors  46 ,  248  the magazine  40  can be positioned precisely in vertical and longitudinal position.  
         [0055]    [0055]FIG. 8 illustrates the pushers  150 ,  152  each comprising a pneumatically operated cylinder  270  which acts on a through rod  272 . A first end  272   a  of the through rod  272  is operable to lift the edge  44   b  of the flattened case  44   a.  Preferably the pusher  150  is tilted upwardly in a forward direction as shown in phantom in FIG. 6. This assists in pushing the edge upwardly and outwardly to clear the retaining lips  149 . A sensor switch  150   a  is operatively oriented with an opposite end  272   b  of the rod  272  such that movement of the rod can be indicated and the signal communicated to the controller  38 . A similar switch  152   a  is provided for the pusher  152 .  
         [0056]    [0056]FIG. 9 illustrates the transport mechanism  26  in more detail. A vacuum pump  302  is tube-connected to the suction cup  52 . The vacuum pump  302  is actuated by pneumatic pressure from a tube  306 . The pneumatic cylinder  162  includes a through rod  308  which is moveable in a longitudinal direction. A first end  308   a  is connected by a bracket  310  to the stationary magazine structure. The cylinder body  309  is fixed by an L-shaped bracket  312  to a base end  314  of the rod  50 . Under pneumatic pressure in one direction, the cylinder body  309  is drawn toward the bracket  310  which causes the rod  50  to pivot away from the magazine  40 . Upon selected differential pneumatic pressure in an opposite direction, the cylinder body  309  is moved away from the bracket  310  which causes the rod  50  to pivot toward the magazine  40 . An opposite end  308   b  of the rod  308  is moveable close to a proximity switch  320  which sends a position signal of the rod  50  to the controller  38 .  
         [0057]    The joint  158  is formed by a through shaft  326  connected via a yoke  328  to the arm  50  and which shaft  326  passes through a front face of the magazine  40  and is connected at a rear thereof to the pneumatic cylinder  164  via a crank lever  330 . The position of the arm  50  is detected by an optical sensor  331 .  
         [0058]    The joint  154  is formed by a short axle which is fixed to the arm  50  and which passes rotationally through opposite arms of the yoke  328 , allowing pivoting motion of the axle  336  with respect to the yoke  328 .  
         [0059]    The joint  159  is formed by a yoke  340  extending at a top of the arm  50  and an axle  342  fixed to a mount housing  346  of the suction cup  52  and rotationally carried by opposite arms of the yoke  340 .  
         [0060]    [0060]FIG. 10 illustrates the sensor  60 , preferably an optical sensor, mounted on a flexible arm or rod  364  which guides the sensor  60  along the predominant facing surface of the case  44   a.  The flexible arm  364  extends from a plate  368 . The plate  368  is connected to the moveable carriage  159  which is carried by the transport rod  166 . The bearing  167  is mounted above the plate  368  and together with the guide rod  168  ensure stability and verticality of the sensor  60 . The bearing  167 , the carriage  159 , the plate  368  and the sensor  60  move together along the transport rod  166 .  
         [0061]    A stationery plate  372  is oriented in the transverse path of the case  44   a.  A spring  374  extends upwardly in the path of the case  44   a  such that the case flexes the spring. The force exerted by the spring assists in opening the case  44   a.    
         [0062]    [0062]FIG. 15 illustrates the control scheme of the present invention. The controller  38  includes a programmable logic controller (PLC)  400 , a servomotor drive  404  and a solenoid manifold  408  having solenoid valves responsive to an I/O section  410  of the PLC  400 . The PLC  400  receives a case size signal from the sensor  60  when the sensor finds the case slot  136 . If the case size has changed from the previous case size, the PLC  400  sends appropriate signals to the servomotor  46  via the drive  404  to adjust the elevation of the magazine. The PLC  400  sends a signal to the servomotor  248  via the drive  404  to adjust the longitudinal, horizontal position of the magazine  40 . The PLC  400 , via the drive  404 , controls the stroke of the conveyor  68  and the conveyor  84  of the transport units  28 ,  32  respectively according to the particular size of the case, by controlling the servomotors  70 ,  85 . The PLC  400 , via the drive  404 , adjusts the separation between conveyor belts  102 ,  104  by sending a signal to the servomotor  106 .  
         [0063]    During operation, the apparatus must be carefully timed and controlled by the controller  38 . The controller  38  initiates movement of the pivot arm  50  by sending the appropriate signal via the I/O  410  and a solenoid valve within the manifold  408 , to the pneumatic cylinder  164 , and sends a signal via the I/O  410  and a solenoid valve within the manifold  408 , to the pushers  150 ,  152  to lift and separate the first case  44   a  from the retaining lips  149  of the magazine  40 . The sensors  150   a,    152   a  confirm activation of the pushers  150 ,  152  to the PLC  400 . The optical sensor  331  senses the correct rotational position of the pivot arm  50  about the joint  158  with respect to the leading flattened case  44   a  and sends a corresponding signal to the PLC  400 . The controller then instigates forward pivoting of the arm  50  about the joint  154  toward the case  44   a  by a signal to the pneumatic cylinder  162  via the I/O  410  and a solenoid valve within the manifold  408 .  
         [0064]    The position of the suction cup  52  with regard to the case  44   a  is sensed by the proximity switch  320  which communicates this information to the PLC  400 . The suction cup  52  can be activated by a signal from the PLC  400  via the I/O  410  and a solenoid valve within the manifold  408 , to engage the leading case  44   a.  The pivot arm  50  can then be pivoted down about the joint  158  by the cylinder  162  to the staging area, to set the case  44   a  on the ledge  56 .  
         [0065]    The PLC  400  initiated movement of the sensor  60  along the transport rod  166  can then commence. The PLC  400  instigates movement of the carriage  159  from the preset home position  169  and starts a timer or clock function within the PLC  400 . Upon finding the slot  136 , the optical sensor communicates this position to the PLC  400  and the timer or clock function is stopped. The PLC  400  calculates the case size based on the duration of carriage travel as measured by the timer or clock function. At this point the case size is either confirmed as being appropriate for the present configuration of the apparatus  20 , or if the case size has changed, plural adjustments are made by the controller  30  to accommodate the new size case.  
         [0066]    Although a timer or clock function is used to determine the location of the sensor  60  when the slot  136  is found, other distance measuring sensors or techniques would be used, such as a servomotor or numerically encoded motor to move the carriage  159 , by a magnetic or electric “yardstick” incorporated into one of the rails  166 ,  168 , or by other means. Although a moving optical sensor is described, other sensors could be used to scan the leading flattened case to determine the case size.  
         [0067]    Each of the servomotors which set apparatus adjustments are provided with a position feedback to the controller  38 . The servomotors  248 ,  46 ,  85 ,  70 ,  106  provides position feedback respectively to the PLC  400  via the servodrive  404 . The aforementioned motors can be numerical motors having numerical encoders which feedback the precise position of the respective adjustment to the controller  38 .  
         [0068]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.