Variable Count Slicing Of Food Products

Abstract

A method and apparatus for slicing a slab of a food product, such as bacon, into drafts of predetermined weight by varying the slice count in each draft while maintaining the slice thickness essentially uniform, in order to compensate for variations in the dimensions of the slab. The thickness and the width of the slab are individually sensed as the slab is advanced into a slicing blade, the slice count in each draft being varied in accordance with changes in the thickness of the slab while the rate of advancement is controlled in accordance with width variations. Rather than slicing the slab, the dimensional information derived from sensing the slab thickness may be utilized for grading purposes.

Description

In the commercial slicing and packaging of bacon, the bacon slabs are commonly sliced into half-pound, 1 pound, or 2 pound drafts which are then individually packaged in a process line operation. A rotary blade slicing machine is utilized, the bacon slices cut by the blade being deposited on a moving conveyor as a slab is continuously advanced into the blade. It is desired that some means be employed to momentarily terminate the slab feed as each pound, for example, is cut, while the conveyor remains in motion, in order that pound drafts of bacon ready for packaging will be laid on the conveyor in spaced groups.

One prior approach to automatic control of the slicing operation in accordance with the weight of the drafts utilizes inmotion weighing of each draft as it is cut and deposited on the conveyor. In this system, the feed of the slab into the blade is momentarily stopped at the weight cutoff point. The control has an inherent disadvantage, however, in that accuracy is difficult due to the necessity of weighing the slices while the conveyor is in motion and, furthermore, due to the attendant probability that undamped vibrations will be induced in the weighing mechanism by the slices falling on the weighing table.

In another prior system, a uniform slice count for each draft is employed but the speed of the slab feed is automatically varied in accordance with either the primary variable dimension (thickness) of the slab or both such dimension and the width of the slab. This approach involves the use of sensing fingers which engage the slab to determine its dimensions as it is fed into the blade, the response of the fingers then being utilized to control the rate of feed of the slab to vary the slice thickness in accordance with dimensional variations. A thinner slab, of course, is sliced thicker, and a thick slab correspondingly thinner, in order to meet the fixed weight requirement with a fixed number of slices. However, the variable slice thickness approach has an inherent disadvantage in that consumers oftentimes desire bacon of a particular thickness and make a purchase based on the representation on the packaging that the bacon contained therein is of such thickness. For this reason, wide fluctuations in thickness for a particular stated cut are undesirable from the consumer standpoint.

Another important consideration in bacon processing is the percent acceptability of the drafts, i.e., the percentage of the drafts which are actually within the allowed weight tolerance. In order to check each draft after slicing, an inmotion weight check is customarily provided, those drafts not within the tolerance being diverted from the main line to be hand-scaled. The drafts within the tolerance may, of course, be immediately packaged without the necessity of the additional labor required in the case of the rejected drafts.

It is, therefore, the primary object of the present invention to provide a method and apparatus for slicing a slab of a food product, such as bacon, into drafts of predetermined weight, without the disadvantages discussed above with respect to the inmotion weighing and the variable slice thickness system.

As a corollary to the foregoing object, it is an important aim of this invention to provide a method and apparatus as aforesaid in which the thickness of individual slices is maintained essentially uniform, but the slice count is varied for each draft in accordance with dimensional changes in the slab in order to compensate for such changes and provide drafts of uniform weight.

Furthermore, it is an important object of this invention to provide a method and apparatus as aforesaid capable of providing a high percentage of acceptable drafts within the required weight tolerance, in order to reduce the incidence of hand-scaling.

Still another important object of the invention is to provide a method of determining the number of slices of a slab of a food product constituting a draft thereof of a predetermined weight.

As mentioned hereinabove, in the slicing of bacon slabs the thickness of the slab is the prime variable dimension and may, for example, be from 11/4 to 21/4 inches. From the standpoint of percentage deviation, variations in the width of the slab are considerably less appreciable since such slabs are commonly between 8 and 10 inches wide. Therefore, it is another important object of the present invention to effect variation of the slice count as aforesaid in accordance with the thickness of the slab while the slice thickness is varied only in accordance with the width, thereby maintaining the slice thickness uniform insofar as visual detection of variation is concerned.

As a corollary to the above object, it is also an important aim of this invention to provide a control method and apparatus governed in accordance with the equation (Wt )(NT)= K, where W is the width of the slab, t is the slice thickness, N is the number of slices, T is the thickness of the slab, and K is a constant determined by the weight of the draft and the density of the product, wherein Wt is maintained equal to a constant K.sub.1 and NT equal to a constant K.sub.2.

Yet another important object of the invention is to provide a control system in which a fractional slice may be cut in instances where the weight of each draft must be kept within sufficiently close tolerance limits that integer slice counts would produce an undesirable percentage of unacceptable drafts.

Additionally, it is an important object of this invention to provide a method of measuring a variable dimension of a slab of a food product for the purpose of grading the product in accordance with such dimension.

In the drawings:

FIG. 1 is a top plan view of a bacon slicing machine provided with the control system of the present invention;

FIG. 2 is an enlarged, front end view of the machine of FIG. 1 showing the slicing blade and the top sensing fingers, the blade cover being removed;

FIG. 3 is a further enlarged, fragmentary, vertical sectional view through the front end wall of the machine showing the top sensing fingers and the rotary step switch, parts being broken away and the housing of the switch shown in section to reveal details of construction;

FIG. 4 is a rear view of the top finger assembly on the same scale as FIG. 3, the cover and the holddown members being removed for clarity;

FIG. 5 is a top plan view of the rotary step switch on the same scale as FIG. 3, the housing being broken away and the switch drum shown in cross section;

FIGS. 6 and 6A comprise a combination block and electrical schematic diagram illustrating electrical and electromechanical components of the control system;

FIG. 7 is a schematic representation of the step switch of FIGS. 3 and 5 showing the arrangement of the reed switches and illustrating one position of the permanent magnet switch elements relative to the reed switches; and

FIG. 8 is a graph illustrating the response of the step switch to variations in slab thickness.

THE SLICING MACHINE

Referring particularly to FIGS. 1 and 2, a bacon slicing machine 10 is illustrated which, insofar as its basic mechanical components are concerned, is of standard design. The machine 10 has an elongated base frame 12 provided with a pair of upstanding end walls 14 and 16 which will be referred to as the front and rear end walls respectively. A bearing 18 is supported by the front wall 14 and a bearing 20 is mounted on the rear wall 16, such bearings 18 and 20 serving to journal a shaft 22 that extends substantially the length of the machine above a stationary table 24. A rotary slicing blade 26 is attached to the forward end of the shaft 22 in front of the wall 14, and is normally disposed within a cover 28 hinged as indicated at 30 to provide access to the blade 26 when necessary.

A belt and pulley assembly 32 couples the rear end of the shaft 22 to a drive motor 34, the latter also being utilized to drive a hydraulic pump 36 forming a part of the hydraulic system of the machine. The hydraulic system is utilized to supply oil under pressure to a double-acting cylinder 38 disposed in parallelism with the shaft 22 and extending rearwardly from the machine as is clear in FIG. 1. It may be appreciated that the cylinder 38 is thus relatively long in length, and is provided with a piston rod 40 extending from the front end thereof. The end of the piston rod 40, when the latter is fully extended, is shifted to a position adjacent the front wall 14. Accordingly, the piston rod 40 is coupled to a reciprocable carriage 42 which overlies the table 24 and is utilized as a ram or pusher to advance a slab of bacon (not shown) into the slicing blade 26. As may be appreciated by a comparison of FIGS. 1 and 2, an opening 44 in front wall 14 permits a bacon slab on table 24 to be advanced by the carriage 42 through the wall 14 and into the rotating blade 26. A fixed blade 46 (FIG. 2) is mounted on the front of the wall 14 and cooperates with the rotating blade 26. A belt conveyor (not shown) would pass beneath the blade 26 and 46 for the purpose of receiving the slices of bacon as they are cut from the advancing slab.

THICKNESS SENSING AND STEP SWITCH

The mechanical details of the control system of the present invention relating to thickness sensing are illustrated in FIGS. 3-5 with incidental reference to FIGS. 1 and 2. A top finger assembly is broadly denoted 48 and has four sensing fingers 50, 52, 54 and 56 spaced across the table 24 at its forward end adjacent the front wall 14. These four fingers 50-56 ride on the top surface of the slab for the purpose of sensing the thickness of the slab at four spaced points, just prior to introduction of the leading edge of the slab into the slicing blade 26. The assembly 48 is disposed beneath the shaft bearing 18, and the fingers 50-56 may be seen in FIG. 2 in alignment with the opening 44 in front wall 14.

A horizontal mounting bar 58 is secured to front wall 14 a short distance above the opening 44 and carries a pair of sideplates 74 of the finger assembly 48. A laterally extending lever arm 59 is pivotally mounted at 60 where it passes through an opening in the right sideplate 74 (as viewed in FIG. 4). The inner end of the arm 59 is downturned and carries a pivot pin 61 upon which a center link 62 is mounted. The link 62 pivots about its center, the opposed ends thereof pivotally supporting a pair of shorter, end links 64 and 66. Each of such end links also pivots about its center, the outboard and inboard ends of the link 64 being connected to a pair of upper arms 68 and 70 respectively. An upper, horizontal shaft 72 spans the sideplates 74 and serves to pivotally mount the arms 68 and 70 adjacent their upper ends as is clear in FIG. 3. The lower ends of the arms 68 and 70 are pivotally connected to fingers 50 and 52 respectively, the latter also being pivotally joined to the lower ends of a pair of lower arms 76 and 78. A lower shaft 80 parallel to the upper shaft 72 pivotally mounts the lower arms 76 and 78 at their upper ends, thus a parallel linkage arrangement is provided for the fingers 50 and 52.

Similarly, the end link 66 has its ends connected to a pair of upper arms 82 and 84, the latter being pivotally mounted on the upper shaft 72. The finger 54 is secured by pivotal connections to the lower ends of arm 82 and a lower arm 86, the latter being pivotally mounted on shaft 80. Another identical parallel linkage arrangement is provided for the finger 56 by the arm 84 and a lower arm 88. When the thickness of the slab is not being sensed, the arms 84 and 88 extend forwardly in approximately a horizontal attitude by virtue of a pivotal connection of the upper arm 84 to the piston rod 90 of a single acting pneumatic cylinder 92. Three holddown members 94 are mounted between the fingers 50-56 and are supported by a cross-shaft 96 spanning the sideplates 74, each member 94 being spring-biased downwardly by a suitable spring (not shown) contained within a mounting collar 98 that secures the upper end of the member 94 to the shaft 96. A protective cover 98 for the finger assembly 48 is attached to the mounting bar 58 and sideplates 74.

An upright rod 100 is pivotally connected at its lower end to the outer end of the lever arm 59, the upper end of the rod 100 being pivotally connected to a swingable arm member 102 within a housing 104 that encases a step switch 106. A horizontal mounting bar 108 extends rearwardly from front wall 14 and has a vertical opening 110 extending therethrough which receives the arm member 102 as well as the upper end of the rod 100. A pivot pin 112 in the bar 108 mounts the member 102 for swinging movement about a horizontal axis extending in parallelism with the axes of the shafts 72 and 80 of the finger assembly 48. The member 102 carries a gear segment 114 in mesh with a pinion 116 keyed to a shaft 118 rotatably supported by the bar 108. A rotor 120 of nonmagnetic material is fixed to the shaft 118 and is provided with a pair of diametrically opposed magnet holders 122, each of which carries a permanent magnet 124. (The position of the rotor 120 is different in FIGS. 3 and 5 for clarity of illustration of the holders 122 and magnets 124.) A drum 126 of nonmagnetic, insulating material is mounted on bar 108 in coaxial alignment with the axis of shaft 118, the inner surface of the drum 126 being in close proximity to the magnets 124 to thereby define a very narrow airgap between each magnet 124 and the adjacent portion of such inner surface.

As the shaft 118 is rotated, each magnet 124 traverses the arc of a circle and sweeps along a bank of normally open reed switches 128 embedded within the drum 126. Two such banks 128 are thus employed and are simultaneously swept by the two magnets 124. The end of shaft 118 opposite the rotor 120 is provided with a grooved disc 130 to which a Negator spring (not shown) is attached in order to place a constant bias on the pinion 116 in one direction to take up any lost motion in the mechanical connections from the rotor 120 back through the finger assembly 48.

The schematic representation in FIG. 7 best illustrates the arrangement of the banks of reed switches 128 of the step switch 106. In FIG. 7, the layout of the individual reed switches is planar rather than arcuate so that the manner of spacing and interconnecting the various reed switches may be readily understood. The various reed switches are designated by numbers from -8 to +7. It may be appreciated that each such designation is applied to two reed switches connected in series, one lead of each series pair being connected to a common bus 132. The remaining leads are connected to control circuitry to be subsequently described.

The permanent magnets 124 are illustrated in phantom lines and may be considered to be a rectilinearly movable switch element having a plurality of positions, the particular switch position illustrated being that position corresponding to actuation (closure) of the two -1 reed switches in the left bank 128. It may be observed that the left magnet 124, if moved upwardly a short distance, would also overlie both of the reed switches designated -2 and, finally, continued movement would result in the magnet passing the lower -1 reed switch while both of the -2 switches remain under the influence of the magnetic field. This same overlapping effect occurs as the magnets 124 move from any one position to the next position. Thus, a given switch position corresponds to the actuation of two reed switches of the same designation, and at the transition point between two adjacent positions there will be two pairs of reed switches of like designation in an actuated condition.

WIDTH SENSING

Referring to FIGS. 1 and 2, a side sensing finger 134 is fixed to an upright pivot shaft 136 for swinging movement about the vertical axis defined by the pivot shaft 136. A crank arm 138 is rigidly attached to the shaft 136 beneath the table 24, and a connecting rod 140 extends from the crank arm 138 to an operating arm 142 on the control stem 144 of a valve 146 in the hydraulic system of the machine 10 utilized to drive the carriage 42. Thus, the valve operating arm 142 moves with the crank arm 138, both of the latter being biased in a clockwise direction (as viewed in FIG. 1) by a spring 148 attached to the operating arm 142. The free end of the finger 134, therefore, is yieldably held in engagement with the side edge of a slab of bacon (not shown) on table 24, the point of engagement of the finger 134 with such edge being adjacent the front wall 14 just behind the top sensing fingers 50-56. It is to be understood that the valve 146 is open at all times to a degree dependent upon the position of the finger 134, the latter causing the valve 146 to progressively restrict oil flow to a controlled degree as the finger 134 swings counterclockwise (as viewed in FIG. 1) under the influence of a slab of increasing width, as will be subsequently explained in detail.

COUNTER AND CONTROL SYSTEM CIRCUITRY

In order to count the slices as they are cut from the slab by the rotating blade 26, an interrupter disc 150 is keyed to the rear end of the blade shaft 22, as shown in FIG. 1. The disc 150 is illustrated diagrammatically in FIG. 6A where it may be seen that an arcuate slot 152 is provided in the circumferential periphery of the disc 150. A suitable magnet 154 is illustrated on one side of the disc 150 and a reed switch 156 (shown closed) is schematically illustrated on the opposite side of the disc 150. The disc 150 is of ferromagnetic material and the switch 156 is of the normally open type, thus whenever the disc 150 moves between the magnet 154 and the reed switch 156, the latter cannot be influenced by the magnetic field due to the shunting effect of the disc 150. However, as illustrated, the cutout or slot 152 permits the magnet 154 to close the switch 156, such closure occurring once during each revolution of the slicing blade 26.

A decade counter 158 has a counting input 160 in the form of a pair of leads to the reed switch 156. The counter 158 is responsive to each closure of the switch 156 and thus registers a count as each slice is cut. A tens register 162 and a units register 164 of the counter 158 are illustrated as providing the counter with a digital capacity of from 0 to 39, which is sufficient for purposes of illustration. Four digital leads extend from the tens register 162 and correspond to the 0, 1, 2 and 3 decades as indicated, such leads terminating at four connectors 166, 168, 170 and 172 respectively. Similarly, 10 digital leads extend from the output terminals of the units register 164 designated 0 through 9, and terminate at connectors 174, 176, 178, 180, 182, 184, 186, 188, 190 and 192 respectively. The 14 connectors 166-192 are of the plug and jack type, together with 10 additional connectors 194, 196, 198, 200, 202, 204, 206, 208, 210, and 212, for the purpose of permitting a program plug 214 to be inserted between the 14 connectors 166-192 and the 10 connectors 194-212. As the legend indicates, program plug C is shown in FIG. 6A and is provided with internal leads that connect the connector 170 to all of the connectors 194-202 and interconnect the connector pairs 174 and 204, 176 and 206, 178 180 and 210, and 182 and 212.

Referring to FIG. 6, five of the reed switches of the step switch 106 (FIG. 7) are illustrated, such reed switches being those series pairs designated -2 through +2. The common bus 132 is connected to a normally open switch 216 which forms a part of an AND relay and is operated by a relay coil 218. A lead 220 extends from the switch 216 to the movable pole of a rotary switch 222 (FIG. 6A) utilized to select the point during cutting of each draft when the thickness of the slab is to be sampled. A lead 224 extends from the relay coil 218 to the digital lead of the counter output from the 1 decade of the tens register 162. The other electrical side of the relay coil 218 is connected to a lead 226 which is circuit ground.

Five diodes 228, 230, 232, 234 and 236 connect the reed switch pairs -2 through +2 to the gates of five silicon controlled rectifiers 238, 240, 242, 244 and 246. The anodes of the SCR's 238-246 are connected to a source of positive potential (+V) by a common lead 248 through a switch 250 of a reset relay having a coil 252. Five diodes 254, 256, 258, 260 and 262 connect the cathodes of the SCR's 238-246 in series with five relay coils 264, 266, 268, 270 and 272 respectively, such coils being returned to ground through resistors 274, 276, 278, 280 and 282. The relay coil 264 controls a gang of three normally open relay switches 264a, and likewise, each of the relay coils 266-272 controls a range of three normally open relay switches 266a, 268a, 270a or 272a. The connector 194 associated with the program plug 214 is connected to the center switch 264a, the connectors 196-202 being connected to center switches 266a-272a respectively. The connectors 204-212 extend to the right-hand switches 264a-272a, respectively; therefore, utilizing program C, all of the center switches 264a-272a are excited by the 2 output of the tens register 162, while the right-hand switches 264a-272a are respectively excited by the 0-4 outputs of the units register 164 of the counter 158. For this reason, the legends "20," "21," "22," "23," and "24" appear beneath the corresponding relays in FIG. 6 to indicate that, utilizing program C, energization of the appropriate relay will cause either 20, 21, 22, 23 or 24 slices to be cut from the bacon slab before a dwell in the slab feed (to be discussed) occurs. As an illustration of a form of numerical readout, five electric lamps 286, 288, 290, 292 and 294 are connected between the left-hand switches 264a-272a, respectively, and circuit ground.

A diode 296 connects the cathode of SCR 238 to the resistor 276 at a junction point common to the lead from the relay coil 266. In similar fashion, diodes 298, 300 and 302 connect the cathodes of SCR's 240, 242 and 244 to resistors 278, 280 and 282, respectively.

A diode 304 connects the cathode of the SCR 238 to the coil 306 of an AND relay having a normally open relay switch 308. Diodes 310 and 312 connect the cathodes of the SCR's 242 and 246 to coil 306, thus either of the SCR's 238, 242 or 246 corresponding to reed switch pairs designated by even numbers (-2, 0, and +2) is capable of effecting energization of the relay coil 306. The SCR's 240 and 244, however, corresponding to odd numbered reed switch pairs, are individually connected to the relay switch 308 via a diode 314 from the cathode of SCR 240 and a diode 316 from the cathode of SCR 244.

A diode 318 connects the normally open contacts of the five right-hand switches 264a-272a to a normally open relay switch 320 of an AND relay having a coil 322. A lead 324 connects the normally open contacts of the five center switches 264a-272a to the relay coil 322. Energization of this coil 322 plus the delivery of excitation to relay switch 320 is an AND function which initiates a dwell in the slab feed at the end of the slicing of a given draft. The trigger input "T" of a flip-flop flop 326 is connected to the normally open contact of the relay switch 320, the flip-flop outputs being designated "0" and "1." The "0" output is connected to the coil 328 of a relay having a normally open switch 330, the movable pole thereof being connected to the trigger input "T" of the flip-flop 326. The "1" output of flip-flop 326 is connected to the set input "S" of a flip-flop 332 through an RC timer 334, the latter serving to delay the triggering of the flip-flop 332 during startup of the carriage drive for synchronization purposes. The "1" output of the flip-flop 332 is connected via lead 335 to an output relay 336 (FIG. 6a) that controls a solenoid 338 which operates a hydraulic control valve 340 and a pneumatic on-off valve 342. The line 344 from the hydraulic pump 36 to the cylinder 38 (FIG. 1) is illustrated diagrammatically, it being noted that the valve 146 and 340 control the flow of oil to the cylinder 38. The valve 342 is diagrammatically illustrated interposed in a line 346 which supplies air under pressure to the pneumatic cylinder 92 when valve 342 is open.

The "0" output of the flip-flop 326 is also connected to a RC timer 348 which functions as a delay during deactuation of the carriage drive by the control system. This delay is a "full slice" delay as indicated by the legend, meaning that the delay in initiation of shutoff of the carriage drive is to synchronize shutoff with movement of the blade 26 such that the last slice of the draft being cut will be a full slice thickness. The output of the timer 348 is connected to the normally closed contact of a relay switch 350 forming a part of a latch relay 352 having a pair of coils 354 and 356. A lead 358 connects the movable pole of the switch 350 to the reset input "R" of the flip-flop 332 through a diode 360.

The latch relay 352 executes a memory function when the foil 354 is energized to shift the position of the switch 350 to close the movable pole against the left-hand (normally open) contact. The output of the full slice delay timer 348 is connected to a one-half slice delay timer 362 which is, in turn, connected to the mentioned normally open contact of the switch 350, thus the two delay timers 348 and 362 are placed in series with each other when the relay coil 354 is energized.

In FIG. 6A a rotary switch 364 is illustrated having ten contacts connected to the respective digital leads of the units register 164 of the counter 158. The rotor of the switch 364 is connected by a lead 366 to the reset coil 356 of the latch relay 352. A diode 368 is connected from lead 366 to a normally open switch 370 of an AND relay having a coil 372. The movable pole of the switch 370 is directly connected to the normally open contact of the relay switch 330. The rotary switch 364, in conjunction with relay coil 372 and its switch 370, controls the time duration of the dwell of the carriage drive between successive drafts. Note in this respect that a lead 374 connects the relay coil 372 to the 0 lead from the tens register 162 of the counter 158.

In FIG. 6A a suitable electrical power source 376 for the counter 158 is connected thereto through a reset control 378 which may comprise an electromechanical relay or other electrically responsive switching means. The counter 158 is automatically reset to zero whenever power is removed therefrom by operation of the reset control 378. Accordingly, a lead 380 extends from the "T" input of the flip-flop 326 (FIG. 6) to the reset control 378 through a diode 382. For manual startup, a manual reset switch 384 is provided which, when actuated, operates a latch relay 386 that, in turn, is connected to the reset control 378 through a diode 388, and is also connected by a lead 390 to the R inputs of flip-flops 326 and 332, the connection to flip-flop 332 being effected via a diode 392 (FIG. 6). Release of the manual reset 384 enables a monostable multivibrator or the "one-shot" 394 which has its output connected to the lead 380 by a diode 396. The control input of the one-shot 394 is connected to the blade rotation responsive reed switch 156 by a pair of leads 398.

CALIBRATION OF THE CONTROL

Operation of the control system is programmed in accordance with the desired weight of the individual drafts and the selected slice thickness. It will be assumed hereinafter that the machine is to be utilized to slice bacon into 1 pound drafts; therefore, the density of bacon being known, the volume of the bacon that must be sliced for each 1 pound draft may be readily computed. This volume is 27.7 cu. in. and will be referred to as a constant K.

As set forth hereinabove, (Wt )(NT)= K, where W is the width of the slab, t is the slice thickness, N is the number of slices, T is the thickness of the slab, and K is the above constant just discussed. In order for K to remain a constant and hence for each draft to have a weight of 1 pound, Wt is maintained equal to a constant k.sub.1 and NT is maintained equal to a constant k.sub.2. Since W and T are dimensions of the slab and thus cannot be changed, t and N are varied in order to compensate for variations in W and T. Furthermore, in utilization of the control it is necessary that the operator be able to choose the value of slice thickness t in accordance with the desired cut. The following table is employed for this purpose, and assumes a slab thickness of 1.5 inches:

Program A B C D E __________________________________________________________________________ Reference count 17 19 21 23 25 Step switch position -3 -2 -1 0 +1 k.sub.2 =NT 25.5 28.5 31.5 34.5 37.5 k.sub.1 =Wt 1.086 0.972 0.879 0.803 0.739 __________________________________________________________________________ Slice thickness minimum 0.109 0.097 0.088 0.080 0.074 Slice thickness average 0.121 0.108 0.098 0.089 0.082 Slice thickness maximum 0.136 0.122 0.110 0.100 0.092 __________________________________________________________________________

The above values for slice thickness are expressed in inches. As an example, assuming that the desired average slice thickness is 0.098 in., it may be seen from the table that Program C is utilized and that the step switch is set at the -1 position for a slab thickness of 1.5 inches. At this setting, the reference count is 21, i.e., a 1 pound draft cut from a slab 1.5 in. thick will contain 21 slices. The actual slab thickness may vary considerably from the arbitrary value of 1.5 in. used for calibration; this, in turn, will cause the slice count in each draft to vary accordingly. However, it may be seen from the table that the variation in slice thickness is only over a range of plus or minus approximately 10 percent since an average slab will have a width of 9 inches with maximum and minimum values being 10 and 8 inches respectively.

To facilitate calibration, a block or dummy slab having a thickness of 1.5 in. is placed on table 24 under the top sensing fingers 50-56. A manual override (not shown) in the pneumatic system for the cylinder 92 may be utilized during calibration to pressurize the cylinder 92 and extend the piston rod 90 so that all of the fingers 50-56 will be in contact with the top surface of the dummy slab. The purpose of the cylinder 92 during actual operation is to take up mechanical backlash and lost motion in the finger assembly 48.

The connecting rod 100 (best seen in FIG. 3) has an adjustable coupling (not shown) which allows the length of the rod 100 to be increased or decreased for calibration purposes. With the fingers 50-56 resting on the dummy slab, the length of the connecting rod 100 is adjusted to bring the rotor 120 of the step switch 106 to the position where the two -1 red switches are both closed. For convenience in aligning the step switch 106, the rear portion of the housing is removable and index marks (not shown) would be placed on the drum 126 to assure accurate alignment at the required position.

The program plug for Program C (FIG. 6A) is inserted between the counter output connectors 166-192 and the connectors 194-212 of the control circuitry. This presets the reference count of 21 at the center relay switch 266a which will be operated when both -1 reed switches are closed.

The width sensing side finger 134 is calibrated by the hydraulic system. Utilizing a dummy slab 10 in. wide (the maximum expected width), the hydraulic control valve 340 is set so that, in the open position, the flow of hydraulic fluid in the line 344 to the cylinder 38 will be such as to advance the carriage 42 at a speed corresponding to a slice thickness of 0.088 in. This value of slice thickness is the minimum thickness for Program C and is increased to 0.098 in. (the desired average slice thickness) when a slab 9 inches wide is actually being fed into the blade 26. This is the case due to the action of the valve 146 in increasing fluid flow in accordance with the degree to which the side finger 134 is displaced in a clockwise direction (as viewed in FIG. 1) in accordance with slab widths of less than 10 inches.

The five programs set forth in the above table are illustrated graphically in FIG. 8 where the number of slices constituting 1 pound is plotted as the ordinate, and the slab thickness is the abscissa. It may be seen that the curved k.sub.2 lines correspond to the values of k.sub.2 associated with the five programs. For Program C, the value of k.sub.2 is 31.5, thus the product of the coordinates of any point along the 31.5 k.sub.2 curve is equal to this value. It may be observed that the relationship between the number of slices and the slab thickness is nonlinear and, furthermore, that the k.sub.2 curves are progressively more closely spaced with increasing slab thickness. The intersecting curves designated -4 through +1 represent the step switch positions which solve the equation, i.e., correspond to the number of slices that will produce a one pound draft. It should be understood that the designations given the step switch positions are entirely arbitrary, and it may be appreciated that the spacing of the switch positions is necessarily irregular in accordance with the nonlinear relationship evidenced by the graph of FIG. 8.

OPERATION

The motor 34 is in operation at all times, thus the slicing blade 26 rotates continuously at a constant speed. With the carriage 42 in a retracted position as illustrated in FIG. 1, a slab of bacon is placed on the table 24 in front of the carriage 42 and against a side guide 24a. A manual start-stop switch (not shown) is then actuated to commence forward movement of the carriage 42. This may be effected by triggering the flip-flop 326 to cause delivery of an output voltage level at its "1" output which, in turn, energizes the output relay 336 to activate the solenoid 338 controlling the valves 340 and 342. Both of the valves 340 and 342 are closed when the solenoid 338 is deenergized, and open in response to energization of the solenoid 338 to deliver hydraulic fluid to the carriage 42 and activate the pneumatic cylinder 92. Since the bacon slab is spaced rearwardly of the top sensing fingers 50-52 at this time, the finger 56 will be advanced downwardly to the lowermost position thereof permitted by its supporting linkage, and the other fingers 50-54 will be in their lowermost positions as illustrated in FIGS. 2-4. In such positions, the rotor 120 of the step switch 106 is at an extreme position where both of the permanent magnets 124 are out of range of the +7 reed switches. It will be appreciated hereinafter when the control system is fully discussed that, with none of the reed switches closed, the control system is inoperative and the carriage 42 is permitted to advance without interruption.

When the bacon slab approaches the blade 26, the top sensing fingers 50-56 ride up on the upper surface of the slab and the outside longitudinal edge thereof is engaged by the side finger 134. Air pressure in the cylinder 92 is maintained sufficiently low to permit the top finger 56 to raise the piston rod 90 in accordance with the slab thickness. If no action is taken by the operator, slicing will then commence and ultimately terminate at the end of the first draft due to the action of the control system. However, this first draft would be below weight due to the spacing between the top sensing fingers and the blade 26. Furthermore, the first several slices of a slab are low-grade slices requiring separation from the rest of the slices to be cut from the slab, thus the following procedure is utilized.

Once the slicing blade 26 begins cutting slices and has sliced off the low-grade product, the operator momentarily actuates the manual reset switch 384 to stop the advancement of the carriage 42 and reset the counter 158, the latter having been in operation prior to this time since each rotation of the blade 26 is continuously sensed by the magnet 154, interrupter disc 150, and reed switch 156. Activation of the manual reset switch 384 operates the latch relay 386 which, in turn, operates the zero reset control 378 to remove power from the counter 158 and maintain the latter inactive until the latch is released, as will be discussed. At the same time that the zero reset control is operated by the latch relay 386, the latter effects resetting of both of the flip-flops 326 and 332 to stop the forward movement of the carriage 42.

Actuation of the manual reset switch 384 also enables the one-shot 394 so that the latter is now sensitive to the next revolution of the blade 26. When this is sensed, the one-shot 394 delivers an output signal which resets the latch relay 386 and, via lead 380, triggers the flip-flop 326. Accordingly, the power source 376 is reconnected to the counter 158 and the flip-flop 326 again delivers an output voltage level at its "1" output to set the flip-flop 332. As before, this effects energization of the valve solenoid 338 to open the valves 340 and 342. The "start" delay timer 334 is set as necessary to synchronize startup of the carriage drive with the rotation of the slicing blade 26.

Although the width of the slab is sensed continuously by the side finger 134, the thickness of the slab is sampled at a particular slice count during the slicing of each draft. The sample point is selected by the rotary switch 222 which, as illustrated, is set to sample the slab thickness at slice number 13 of the draft. The rotary switch 222 illustrated herein permits sampling at slices 12 through 16, the lead 220 comprising a "units" lead from the pole of the switch 222 to the relay switch 216. The lead 224 comprises a "tens" lead to the relay coil 218. Thus, the AND function is executed on count 13 from the counter 158 since at that time, both the relay coil 218 is energized and excitation is available at the switch 216. This, in turn, energizes the common bus 132 of the step switch 106 during the time at the count is at 13. Therefore, during the period of the 13th count, whichever series pair of reed switches in the step switch 106 is closed with effect triggering of the corresponding SCR 238-246. In the simplified illustration of the control system herein, only the five pairs of reed switches -2 through +2 are shown, it being understood that the reed switch-SCR circuitry is actually duplicated for each step switch position from -8 to +7.

The sample point would be selected in accordance with operator experience as to the transverse zone of the slab best representative of the average slab thickness for each draft. Assuming for purposes of illustration that the slab is 1.5 inches thick (the same as the dummy slab used for calibration) then both of the -1 reed switches would be closed in response to the mechanical output of the top fingers 50-56, such mechanical output being representative of the average slab thickness at the four points across the top of the slab engaged by the four fingers 50-56. Averaging is accomplished by the action of the pivotal links 62, 64 and 66 which sum the vertical displacements of the four fingers and cause the lever arm 59 to swing about pivot 60 in proportion to the average value of such displacements. The circuit through the two closed -1 reed switches effects triggering of the SCR 240 via the diode 230 and attendant energization of the relay coil 266. The three relay switches 266a are closed, the closure of the left-hand switch effecting energization of the lamp 288 to readout 21 for monitoring purposes. Once gated, the SCR 240 remains in conduction although the trigger, of course, is removed when the count progresses to 14. Ultimately, when the count reaches 21, the digital slice count signals from the counter 158 will be present at connectors 196 and 206. When the digital signal at connector 196 (corresponding to the 20 count) first appeared at connector 196, the relay coil 322 was energized via lead 324. On the next count, the digital units signal is conducted to the relay switch 320 via diode 318, thereby executing the AND function and delivering an output command to the "T" input of the flip-flop 326 to trigger the latter. This stops the movement of the carriage 42 since the output voltage level from the flip-flop 326 now appears at its "0" output, causing resetting of the flip-flop 332 via a circuit through the full slice delay timer 348, relay switch 350, lead 358, and diode 360 to the "R" terminal of flip-flop 332. This deenergizes the output relay 336 to close the valves 340 and 342. Additionally, lead 380 from the "T" input of the flip-flop 326 directly effects resetting of the counter 158 at the time that the flip-flop 326 is triggered by the output command from AND relay switch 320. Furthermore, since the coil 252 of the SCR reset relay is energized via a lead 400 connected to the output of the 0 reset control 378, the relay coil 252 is momentarily deenergized to open its associated switch 250 during resetting of the counter 158, thereby also interrupting anode voltage to the SCR's 238-246 to return the conducting SCR 240 to its nonconducting state.

If, for example, the slab thickness is slightly less than 1.5 in. sufficient to cause the magnets 124 to overlap the -1 and 0 positions (closing both pairs of -1 and 0 reed switches), it should be noted that still only the relay coil 266 is energized due to the action of the diode 298 connected to the cathode of the SCR 240. Although the SCR 242 goes into momentary conduction, the corresponding relay coil 268 will not be energized since both sides of the relay coil 268 are at the same potential. However, a connection via diode 310 from the cathode of SCR 242 energizes the relay coil 306 and, at the same time, a connection via diode 314 from the cathode of SCR 240 energizes the relay switch 308, this relay thus executing its AND function and effecting energization of the latch relay coil 354. Thus, the signal from the relay switch 308 may be appropriately termed a "half-slice signal," such signal being remembered by the latch relay 352 since its switch 350 is shifted to establish circuit continuity through its normally open contact. It will now be appreciated that the delay in stopping the carriage 42 is extended by the presence of the half slice delay timer 362 in series with the full slice delay timer 348, thus a total of 211/2 slices are cut. The half slice is a slice of one-half the normal thickness and, if desired, other fractional slices could be cut as well by inserting the appropriate delay time.

The carriage 42 resumes forward movement following a dwell period preset by the rotary switch 364. The dwell illustrated herein is a time duration equal to seven counts or seven revolutions of the blade 26, as is clear in FIG. 6A. Since the counter 158 is reset as discussed above at the time that the carriage drive is deactivated, the counter 158 starts counting again from zero. Therefore, a preselected number of counts later (which may be varied from 1 to 9), the dwell is terminated by the presence of a digital signal at the pole of the rotary switch 364 which is conducted via lead 366 to the AND-relay switch 370 (through diode 368). The coil of the AND-relay 372 is already energized at this time by virtue of a connection to the 0 digital lead of the tens register 162 via the lead 374. Therefore, the signal from the units register 164 representing the digit 7 is conducted through both the relay switch 370 and the relay switch 330 to the "T" input of the flip-flop 326 to trigger the latter. This occurs since the flip-flop 326, prior to such triggering, is in the "stop" mode and is holding the relay coil 328 energized, thus the relay switch 330 is closed so that execution of the AND function of the relay 370, 372 will trigger the flip-flop 326 back to the "start" mode. The operation then repeats as above for succeeding drafts. The purpose of the dwell between drafts is to space the last slice of one draft from the first slice of a succeeding draft so that each draft deposited on the moving conveyor beneath the blade 26 may be readily identified.

In summary, it may be appreciated from the foregoing that, at each time the slab is sampled to determine the number of slices needed for a one pound cutting, the vertical positions of the sensing fingers 50-56 are indicative of the uncut slab thickness which, in turn, is translated through the control logic to a slice number which will provide a 1 pound draft of bacon for packaging. This slice number may equal the reference count of the program, but will more likely equal an adjusted, final count which varies from draft to draft due to variations in the slab thickness. The graph of FIG. 8 is quite instructive in this respect although it should be understood that the step switch position lines -4 through +1 are somewhat idealized since cutting, in the absence of a half-slice condition, is made to integer numbers rather than to fractional counts. However, the accuracy of the weight of each draft is sufficiently acceptable to be within required tolerances. For Program C used as an example hereinabove, the graph clearly illustrates (following the k.sub.2 =31.5 line) that a change in slab thickness from 1.5 to approximately 1.58 inches necessitates that the slice count be reduced from 21 to 20, the two -2 reed switches being closed in response to such condition rather than the two -1 switches closed at the reference thickness of 1.5 inches.

After the slab has been essentially completely sliced, the top fingers 50-56 drop to their lowermost positions illustrated and deactivate the control system as discussed above since the magnets 124 in the step switch 106 are out-of-range of the reed switches. As the carriage 42 continues forward movement, it engages a stop (not shown) at its forward limit which reverses the hydraulic drive. Thus, rearward movement of the carriage 42 to its retracted position is continuous and uninterrupted. In machines of the type illustrated, a second stop (not shown) at the rearward limit of carriage travel automatically returns the carriage 42 to forward movement.

The teachings of the present invention are also equally applicable to the grading of slabs of food products which may or may not be subsequently sliced. Utilizing the apparatus disclosed herein, the slicing blade 26 would be removed from the shaft 22 and the slab advanced continuously forwardly beneath the top sensing fingers 50-56 (dwell count selector switch 364 set at 0 for no dwell). The side finger 134 is not required. By observing the numerical readout or count at each sampling of the slab thickness, a number indicative of such slab thickness may be derived. Preferably, this is done by averaging the counts for a given slab which, utilizing the apparatus herein, would be effected by manually recording the count at each sampling (as indicated by the monitor lamps 286-294) and then dividing the count total by the number of samplings. If desired, automatic computing may be added to facilitate rapid grading.

Claims

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a machine for slicing a food product:

cutter means;

means for advancing a slab of said product into said cutter means to cut the slab into slices;

a counter for counting said slices and for producing a digital slice count during operation of said slab-advancing means which represents the number of said slices cut by the cutter means;

means adapted to be operably associated with said slab for sensing the size of a variable dimension of the slab transverse to its direction of advancement into said cutter means; and

control means coupled with said sensing means and responsive to the size of said dimension sensed thereby for determining the number of said slices comprising a draft of said product of substantially a predetermined weight, said control means being coupled with said slab-advancing means and said counter and responsive to the slice count therefrom representing said number of slices comprising said draft for deactivating the slab-advancing means to terminate advancement of the slab into the cutter means.

2. In a machine as claimed in claim 1,

said control means being operable to reactivate said slab-advancing means after a predetermined dwell period, and subsequently deactivate the slab-advancing means when a second draft of said product of substantially said predetermined weight has been cut.

3. In a machine as claimed in claim 2,

said cutter means being continuously operable,

said counter being responsive to said cutter means for producing a count signal upon each operation of said cutter means,

said control means terminating said dwell period to effect said reactivation of the slab-advancing means in response to a preselected count signal occurring after commencement of the dwell period.

4. In a machine as claimed in claim 3,

said control means having means for delaying initiation of deactivation and reactivation of said slab-advancing means to synchronize stopping and starting thereof with operation of said cutter means.

5. In a machine as claimed in claim 1,

said control means including a step switch having a plurality of switch positions, means coupling said switch to said sensing means for operation thereby, and circuitry connected with said switch for providing a signal indicative of said number of slices comprising said draft in accordance with the position of said switch.

6. In a machine as claimed in claim 5,

said circuitry including a plurality of electrically responsive devices corresponding to said plurality of switch positions, each of said devices representing a different slice number and being operable to deliver said signal when said switch is in the corresponding position, and means responsive to time coincidence of said signal and the corresponding count from said counter for effecting said deactivation of the slab-advancing means.

7. In a machine as claimed in claim 5,

said switch having a movable element shiftable to each of said positions and overlapping an adjacent pair of positions during transition from one position of said pair to the other position thereof,

said control means further including means responsive to said overlapping of an adjacent pair of switch positions for delaying initiation of deactivation of said slab-advancing means for a time duration sufficient to cause an additional fractional slice to be cut from said slab.

8. In a machine as claimed in claim 1,

and second sensing means adapted to be operably associated with said slab for sensing the magnitude of a second variable dimension of the slab transverse to both its direction of advancement and the first-mentioned dimension,

said slab-advancing means having structure coupled with said second sensing means and responsive to the sensed magnitude for varying the rate of advancement of the slab to maintain the product of said second dimension and the thickness of the slices substantially equal to a constant.

9. In a machine as claimed in claim 8,

the first-mentioned dimension and said second dimension being the thickness and the width of said slab respectively,

said slab-advancing means effecting lengthwise movement of said slab into the cutter means,

the first-mentioned sensing means including a plurality of spaced sensing fingers adjacent said cutter means engageable with a major surface of the slab at spaced points thereacross and movable in response to variations in said thickness, and linkage means interconnecting said fingers and providing a mechanical output representative of the average movement of the fingers.

said second sensing means including a sensing finger adjacent said cutter means engageable with a longitudinal edge of said slab and movable in response to variations in said width.

10. In a machine for slicing a food product where said machine is provided with cutter means and a slab of said product is advanced into the cutter means to cut the slab into slices, control apparatus for producing an output command when the number of said slices constitutes a draft of said product of substantially a predetermined weight, said apparatus comprising:

a counter for counting said slices and for producing a digital slice count representing the number of said slices cut by the cutter means;

means adapted to be operably associated with said slab for sensing the size of a variable dimension of the slab transverse to its direction of advancement into said cutter means; and

output means coupled with said counter and said sensing means and responsive to the size of said dimension sensed by the latter for determining said number of slices constituting said draft,

said output means subsequently delivering said command in response to occurrence of the slice count from said counter representing said number of slices constituting said draft.

11. Control apparatus as claimed in claim 10,

said output means including a step switch having a plurality of switch positions, means coupling said switch to said sensing means for operation thereby, and circuitry connected with said switch for providing a signal indicative of said number of slices constituting said drafts of slices in accordance with the position of said switch.

12. Control apparatus as claimed in claim 11,

said dimension and said number of slices constituting said draft having a nonlinear relationship,

said switch positions being irregularly spaced in accordance with said relationship.

13. Control apparatus as claimed in claim 11,

said circuitry including a plurality of electrically responsive devices corresponding to said plurality of switch positions,

each of said devices representing a different slice number and being operable to deliver said signal when said switch is in the corresponding position.

14. Control apparatus as claimed in claim 13,

said circuitry further including means responsive to time coincidence of said signal and the corresponding count from said counter for effecting the delivery of said command.

15. Control apparatus as claimed in claim 11,

said output means further including means normally maintaining said circuitry inoperative, but responsive to a slice count less than said number of slices constituting said draft for rendering the circuitry operational to cause the latter to sample the size of said dimension and effect delivery of said signal.

16. Control apparatus as claimed in claim 10,

said output means including circuitry for providing a signal indicative of said number of slices constituting said draft, and means normally maintaining said circuitry inoperative but responsive to a slice count less than said number of slices constituting said draft for rendering the circuitry operational to cause the latter to sample the size of said dimension and effect delivery of said signal.

17. Control apparatus as claimed in claim 10,

said dimension being the thickness of said slab,

said sensing means including a plurality of spaced sensing fingers adjacent said cutter means engageable with a major surface of the slab at spaced points thereacross and movable in response to variations in said thickness, and linkage means interconnecting said fingers and providing a mechanical output representative of the average movement of the fingers.

18. Control apparatus as claimed in claim 17,

and means coupled with one of said fingers and maintaining said one finger in pressure engagement with said surface during sensing of said thickness, whereby to take up lost motion in said fingers and said linkage means.

19. In a machine for slicing a food product:

cutter means;

means for advancing a slab of said product into said cutter means to cut the slab into slices;

a counter for counting said slices cut by the cutter means;

means adapted to be operably associated with said slab for sensing the size of a variable dimension of the slab transverse to its direction of advancement into said cutter means; and

control means coupled with said sensing means and responsive to the size of said dimension sensed thereby for determining the number of said slices comprising a draft of said product of substantially a predetermined weight,

said control means being coupled with said slab-advancing means and said counter and responsive to the latter for deactivating the slab-advancing means to terminate advancement of the slab into the cutter means when said number of slices has been cut,

said control means including a step switch having a plurality of switch positions, means coupling said switch to said sensing means for operation thereby, and circuitry connected with said switch for providing a signal indicative of said number of slices in accordance with the position of said switch.

20. In a machine as claimed in claim 19,

said circuitry including a plurality of electrically responsive devices corresponding to said plurality of switch positions, each of said devices representing a different slice number and being operable to deliver said signal when said switch is in the corresponding position, and means responsive to time coincidence of said signal and the corresponding count from said counter for effecting said deactivating of the slab-advancing means.

21. In a machine as claimed in claim 19,

said switch having a movable element shiftable to each of said positions and overlapping an adjacent pair of positions during transition from one position of said pair to the other position thereof,

said control means further including means responsive to said overlapping of an adjacent pair of switch positions for delaying initiation of deactivation of said slab-advancing means for a time duration sufficient to cause an additional fractional slice to be cut from said slab.

22. In a machine for slicing a food product where said machine is provided with cutter means and a slab of said product is advanced into the cutter means to cut the slab into slices, control apparatus for producing an output command when the number of said slices constitutes a draft of said product of substantially a predetermined weight, said apparatus comprising:

a counter for counting said slices cut by the cutter means;

means adapted to be operably associated with said slab for sensing the size of a variable dimension of the slab transverse to its direction of advancement into said cutter means; and

output means coupled with said counter and said sensing means and responsive to the size of said dimension sensed by the latter for determining said number of slices, and responsive to said counter for delivering said command when said number of slices has been cut,

said output means including a step switch having a plurality of switch positions, means coupling said switch to said sensing means for operation thereby, and circuitry connected with said switch for providing a signal indicative of said number of slices in accordance with the position of said switch.

23. Control apparatus as claimed in claim 22, said dimension and said number of slices having a nonlinear relationship,

said switch positions being irregularly spaced in accordance with said relationship.

24. Control apparatus as claimed in claim 22,

said circuitry including a plurality of electrically responsive devices corresponding to said plurality of switch positions,

each of said devices representing a different slice number and being operable to deliver said signal when said switch is in the corresponding position.

25. Control apparatus as claimed in claim 24,

said circuitry further including means responsive to time coincidence of said signal and the corresponding count from said counter for effecting the delivery of said command.

26. Control apparatus as claimed in claim 22,

said output means further including means normally maintaining said circuitry inoperative, but responsive to a slice count less than said number of slices for rendering the circuitry operational to cause the latter to sample the size of said dimension and effect delivery of said signal.