Variable thickness bread slicer

A powered bread slicer capable of slicing successive loaves of bread to selected different slice thicknesses. A rotating circular bread slicing knife is mounted on a pivotal, reciprocal arm for shifting the knife from a retracted position through slicing positions between and transverse to an infeed table and an outfeed table, and return to the retracted position. The slice thickness is selected, as for standard one-half inch thickness, deli one-quarter to three-eighths inch thickness, garlic or French bread up to one inch thickness, or otherwise. A variable stepper motor incrementally advances a loaf pusher one step at a time, the dimension of the step being of the selected slice thickness dimension. The distance by the travelled loaf pusher to reach the end of its travel is monitored to determine whether the bread heal is thick enough to slice once more. This decision is a function of the selected slice thickness dimension. A detector sensing the leading end of the loaf initially activates the slicer knife drive and the support arm drive. A pusher detector adjacent the knife prevents knife advancement with presence of the pusher adjacent the knife, allowing the pusher to move past the knife to push the fully sliced loaf completely onto the discharge table, and then return to the infeed table.

BACKGROUND OF THE INVENTION 
This invention relates to bread slicing machines, and more particularly to 
a variable thickness bread slicer as for delicatessens, bakery stores, 
restaurants and the like, where it is desirable to be able to slice bread 
in varying thicknesses. 
Conventional bread slicers are typically set up to slice loaves of bread to 
a specific thickness. Standard bread slice thickness is one-half inch, 
deli bread thickness is one-quarter to three-eighths inch, and garlic 
bread or French bread is up to one inch in thickness. In small bakeries 
where the bread is sold to customers directly, or other similar 
situations, it would be desirable to be able to adjust the slicer from one 
thickness to another quickly, even for successive loaves of bread for 
successive customers. However, known slicers require substantial 
disassembly and reassembly by a knowledgeable person over a period of 15 
to 30 minutes, to change the slicing thickness. Indeed, some slicers are 
not subject to any variation at all. 
There is a need in the market for a powered bread slicer which can slice 
one loaf to a particular slice thickness, e.g., one-half inch, readily 
slice the next loaf to another thickness, e.g., three-eighths inch, slice 
the third loaf to a third thickness, e.g., one inch or so, and so forth, 
without significant time delay or complexity. 
SUMMARY OF THE INVENTION 
This invention provides a power bread slicer capable of slicing successive 
loaves of bread to varying selected slice thicknesses, even by persons 
untrained in mechanical apparatus. The operator simply selects any of a 
multitude of potential thicknesses and activates the slicer. The bread 
loaf is advanced by a pusher, step-by-step, to be fed to a rotating or 
pivotally reciprocating cutting knife. Each step is of selected thickness. 
The knife may be a revolving circular knife which rotates through a 
slicing stroke and a return stroke, after each feed step, until the pusher 
is adjacent the knife, at which time the knife remains retracted while the 
pusher advances the cut loaf to a discharge position past the knife, and 
returns to the first side of the knife. The slicer works effectively on 
crusty breads such as garlic breads or French breads, as well as on soft, 
somewhat wet breads, such as conventional American bread. 
These and other features, objects and advantages of the invention will 
become apparent upon studying the following detailed specification in 
conjunction with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now specifically to the drawings, the bread slicer assembly 10 
includes a frame and housing subassembly 12 supporting the other 
functioning components. These other functioning components include a 
generally horizontal slide platform subassembly 14 of generally V-shaped 
configuration, to retain a loaf of bread, and made up of a V-shaped infeed 
table 16 and a V-shaped outfeed table 18 on opposite sides of a vertical 
plane containing a circular rotational slicer knife 24. This circular 
knife is rotationally mounted at its center at one upper end of a pivotal 
cutoff arm 28 (FIG. 6), by having a stub shaft 26 on the knife 
rotationally mounted on bearings in arm 28. This arm is pivotally mounted 
at its opposite lower end to a rotating shaft 30. An endless belt drive 34 
extends around pulleys on stub shaft 26 and shaft 30 to form part of a 
drive connection. Another endless belt drive 38 extends around a pulley on 
shaft 30 and a pulley on the output shaft extending from drive motor 40. 
Motor 40 can be a conventional electric motor, e.g., one-half h.p., to 
rotationally drive the knife. The knife has scallops on its outer edge to 
slice bread, when operated to shift transversely to the platform, in the 
manner explained more fully hereinafter. 
Cutoff arm 28 can pivot between an upper knife retracted condition, through 
an arcuate cutoff stroke ending at a lower position, with the knife edge 
below the slide subassembly and any bread thereon (FIG. 4). 
A pivotal safety cover 44 for the knife is pivotally mounted to the housing 
at the upper rear edge of the cover, to move between a lower knife 
covering position (FIG. 1) and a raised knife revealing position (FIG. 2). 
In the lower knife covering position, an inverted, V-shaped opening in the 
side walls of the cover, on each side of the knife, enables passage of a 
loaf of bread B through cover 44 to be operated upon by knife 24. 
Astraddle knife 24 is a pair of downwardly biased, bread hold down fingers 
50 (FIG. 2) to prevent the bread from rising with the raising of, i.e., 
retraction of, knife 24 after a cut is made. 
Cutoff arm 28 is reciprocably operated by cutoff drive motor 70 (FIG. 3) 
through a belt drive 72, a conventional single revolution cutoff clutch 74 
and a crank arm 73, connecting rod 200 to pivot arm 28 from its upward 
position, through an arc, to its full downward position and back to its 
upward position where it engages the cutoff arm return proximity switch 29 
(FIG. 5) to be arrested, awaiting reactivation. 
Pivotally mounted adjacent to, and extending over, infeed table 16 is a 
three dimensional, open bottom, horizontally elongated cover 80 mounted at 
its upper rear edge on pivot hinge 82 to housing 12. It pivots between an 
upper position uncovering infeed table 16 to a lowered position covering 
table 16 and a loaf of bread B thereon. A bread pusher assembly 60 is 
covered by a stationary cover 81 when in a retracted position at the outer 
end of the bread loaf (FIG. 1). Cover 80 has an open discharge end 
adjacent opening 46 in cover 44 to allow bread to be advanced to the 
knife. This cover 80 is preferably transparent, as of polycarbonate, to 
enable viewing of the bread B. A second open bottom cover 86 is pivotally 
mounted at its upper rear edge on hinge 88 to housing 12, to pivot between 
an upper condition (FIG. 2) uncovering outfeed table 18, and a lowered 
position (FIG. 1). It has an open bread receiving end adjacent opening 46 
in cover 44 to receive and cover the bread B after it is sliced. 
There are three safety lockout switches actuated by the three respective 
covers, namely switch 90 for cover 80, switch 94 for blade cover 44, and 
switch 92 for cover 86, to prevent knife 24 from operating and cutoff arm 
28 from lowering if any of the three covers is raised. 
Extending above the slide platform 14 is a pusher assembly 60 including a 
vertical pusher plate 60a and a fork assembly 60b. Pusher assembly 60 is 
capable of moving from an initial position at one end, here the left end 
of the infeed table and slide platform, spaced from knife 24 more than the 
length of a loaf of bread B, toward the knife and ultimately to a final 
position just on the opposite side of knife 24, i.e., at the outfeed 
table, as shown by the phantom lines in FIG. 2. A heel holder plate 20, 
which is mounted for reciprocal travel over outfeed table 18 (FIG. 7), 
maintains the slices together on the outfeed table. 
Pusher assembly 60 is connected by a hitch 61 to underlying belt 98 (FIGS. 
7, 8a and 8b) to be above platform 14, and particularly above infeed table 
16 and outfeed table 18. It is mounted on endless belt drive 98 (FIG. 7), 
to be advanced toward and just beyond knife 24, as described hereinafter. 
Endless member 98 extends around a first pulley 100 beneath the outer end 
of infeed table 16, and a second pulley 102 beneath outfeed table 18. 
Endless drive member 98 is driven forwardly toward knife 24 in preselected 
increments by a variable step, incremental, stepper motor 104 (FIGS. 7 and 
9a-9c) of conventional type, e.g., 200 steps per revolution. It operates a 
gear box which drives pulley 102. The retracted position of pusher 
assembly 60 is controlled by a limit switch serving as an end-of-travel 
switch 108 which is engaged by hitch 61 mounted on drive member 98. The 
furthermost advanced position of pusher 60 is controlled by two limit 
switches, switch 112A near the knife, and switch 112B below drive member 
98, near pulley 100. Switch 112A is actuated by hitch 61, and switch 112B 
is actuated by actuator 110, either switch, if actuated, causing the arm 
28 to be retained in the retracted position. After final retraction of the 
arm, the pusher assembly moves just past the knife for fully shifting the 
complete loaf of bread onto the outfeed table. When the outfeed table 
cover 86 is lifted for removal of the bread, and then closed again, pusher 
assembly 60 returns to the infeed table. In brief, the initial position of 
pusher assembly 60 is at the outer (left) end of infeed table 16 while the 
furthermost position of pusher assembly 60 is just beyond knife 24 above 
outfeed table 18. 
Only pusher plate 60a is directly coupled with hitch 61. Fork assembly 60b 
travels in a channel 60c (FIG. 7) and is frictionally engaged with 
openings in pusher plate 60a. Fork assembly 60b is arrested in motion at 
the end of channel 60c adjacent to knife 24 prior to reaching the knife, 
as illustrated in FIG. 8b. This allows the tines of fork assembly 60b to 
penetrate deeper into a loaf of bread than a typical slice thickness yet 
avoid contact with the knife. The fork assembly tines are reinserted in 
the openings of pusher plate 60a, as pusher plate 60a is retracted to the 
infeed table, as illustrated in FIG. 8a. 
An elongated lower crumb tray 75a for collecting dropping crumbs is 
extendible from a first position inside housing 12 (FIG. 1) beneath the 
slide platform, to a removed condition from the housing for dumping (FIG. 
2 shows partial removal). A generally vertically extending crumb chute 75b 
guides crumbs into crumb tray 75a. 
At the infeed table, immediately before and adjacent knife 24, are two 
photoelectric sensors 19 (FIG. 2) to detect the presence of the leading 
end of a loaf of bread ready to be sliced. If covers 80, 44 and 86 are 
closed, this sensor can activate slicer drive motor 40A and cutoff arm 
drive 70, 72, 74. A resilient wiper (not shown) mounted toward the rear of 
pusher plate 60a wipes crumbs from the Plexiglas covering sensors 19. 
Stepper motor 104 is controllable in conventional fashion using a stepper 
motor driver, and preferably through a microprocessor control 125, to 
allow it to take a predetermined number of the 200 or so incremental steps 
possible per revolution. This enables manual presetting of the dimension 
of each advancing step sequentially taken by the motor, so as to set the 
dimensional distance that pusher 60 moves in each increment. This manual 
setting is readily performed by the human operator by rotating an exposed 
arcuate surface portion 114 (FIG. 2) of a conventional thumb wheel, for 
example, to a "1/2" inch designation indicia thereon, e.g., for the 
one-half inch unit, or to another increment dimension desired, for the 
thickness of the bread slice. The thumb wheel is exposed at 114 on control 
panel 116 which also includes an on-off switch 115, start button 118, stop 
button 120 and indicator light 122. Suitable control circuitry may be that 
set forth in FIGS. 9a-9c and 10a-10b, or the equivalent. 
Referring now to FIGS. 9a-10b, a control 125 is shown connecting AC voltage 
across lines 134 and 136 whenever on-off switch 115 is placed in the ON 
position. A control relay 146 is energized whenever switches 90, 92 and 94 
are closed, indicating that the covers 80 and 86 for the infeed and 
outfeed tables, as well as the safety cover 44 for the knife, are closed. 
Also, with switches 90, 92 and 94 closed, power is fed to the output 
contacts C1 and C2 of the microprocessor to energize a relay 148 provided 
that an output designated OUT 1 of a microprocessor and stepper driver 130 
provides a suitable output command, to thereby apply power to knife drive 
motor 40A, and knife motor brake 40B through relay contact 148a. An output 
designated OUT 2 of microprocessor/stepper driver 130 supplies power to a 
relay 149 which opens contacts 149A and 149B, which removes the drive 
inhibit of DC driver control 127. DC driver control 127 supplies an 
adjustable DC voltage level to cutoff arm drive motor 70. A variable 
potentiometer 150 provides adjustable control of the speed of motor 70 in 
order to allow regulation of the speed at which the arm is moved through 
the bread. A cooling fan motor 152 is energized whenever switch 115 is in 
the ON position in order to supply cooling air to control 125. Indicator 
122 provides a red warning indication whenever microprocessor/stepper 
driver 130 determines that a cover is not properly closed. 
Microprocessor/stepper driver 130 receiving inputs from start switch 118, 
stop/return switch 120, a contact 146b of relay 146, thumb wheel switch 
114, retracted-position limit switch 108, redundant photoelectric bread 
sensors 19a, 19b, redundant end of travel limit switches 112a, 112b and 
cutoff arm return proximity switch 29 (FIG. 9b). Such input devices 
receive supply voltage from input DC supply lines 140 and 138. 
Microprocessor/stepper driver 130 receives supply voltage from DC power 
supply 126 via supply lines 138 and 140. Microprocessor/stepper driver 130 
provides an output OUT 5 to single revolution cutoff clutch solenoid 74 
and an output OUT 4 to counter 151. Output 151 is a 6-digit, manually 
reset counter which counts entire cycles of the apparatus. 
Microprocessor/stepper driver 130 produces step outputs (01-06) 166 that 
are capable of driving stepper motor 104. 
Microprocessor/stepper driver 130 responds to the state of the inputs being 
provided to it and produces outputs to relays 148 and 149, to single 
revolution cutoff clutch solenoid 74 and to stepper motor 104. A control 
program 200 (FIG. 11) establishes the number of steps that stepper motor 
104 is to be incremented. Hence, the data inputs of thumb wheel switch 114 
determine the distance that belt 98 will be incremented, and hence the 
thickness of each bread slice. 
Operation of control program 200, with covers 44, 80 and 86 being closed, 
i.e., lowered, is started by the on-off switch 115 being actuated, 
applying power at 201 to the equipment. The microprocessor/stepper driver 
130 then initiates a self check sequence at 202. During the self check 
sequence, the position of the pusher plate 60a is first checked to see 
whether it is in the outer extreme position. If the pusher plate is not in 
the correct position, the microprocessor/stepper driver 130 will retract 
the pusher plate until it is in the extreme outer position. Then the 
pusher assembly is advanced to the end limit switches 112a and 112b. After 
actuating both limit switches in sequence, the pusher is then retracted 
back to the extreme outer position, ready for operation. If, during the 
self check, it is determined at 204 that either end limit switch 112a or 
112b fails to operate, the microprocessor/stepper driver will enter a 
lockout mode 206 in which operation is stopped, and the operator is 
alerted to a malfunction. The equipment must be turned off to reset the 
microprocessor/stepper driver in order to exit the lockout mode. 
Self check sequence 202 cannot be bypassed. By leaving any of the covers 
44, 80, 86 open when turning on the machine, which is determined at 208 
and places the control in a stop mode 210, the self check sequence can be 
also interrupted during its cycle by pushing the stop button 120. Once the 
microprocessor/stepper driver is in stop mode 210, only by closing the 
doors and pressing the start button will the microprocessor finish its 
self check sequence. 
Once it is determined at 204 that there were no failures during the self 
check mode, the apparatus is in a ready mode 212. During this mode, a loaf 
of unsliced bread is placed on slide platform 14, and specifically on 
infeed table 16, while cover 80 is raised. The outer end of the loaf is 
abutted against pusher plate 60, which is at its outer extreme position, 
with the tines of fork assembly 60b engaging the loaf. The thumb wheel 114 
is set to the desired cut size and the cover 80 is then lowered, as well 
as cover 44 and cover 86 being closed, i.e., lowered. The equipment may 
then be actuated by pushing start button 118. Knife 24 is at this time in 
the retracted elevated condition, i.e., not the cutoff condition. Pusher 
assembly 60 advances bread B toward knife 24 until the product detection 
scanner 19 detects the leading edge of the loaf of bread. At this point, 
the stepper motor will stop, with the leading edge of the loaf being just 
in front of knife 24. At this time, the apparatus enters a slice mode 214. 
In the slice mode, the knife drive motor 40a and slicer arm drive 127 and 
70 are powered up, and the knife brake 40b energized, releasing the knife. 
Once the slicer motor comes up to speed, the stepper motor 104 will index 
one unit width forward, the unit width dimension having been determined by 
the previous setting on the thumb wheel 114. 
The slicer arm will then actuate to lower the knife to cut the first slice, 
and this intermittent incremental sequence will continue until the end 
limit switch 112 for pusher 60 is actuated. When end limit switch 112 is 
actuated, the control enters a last slice mode 216 in which it is 
determined whether the last slice of bread is of a suitable thickness to 
be sliced again into two slices. Microprocessor/stepper driver 130 counts 
the number of pulses between the initiating of the last indexing of belt 
98 and the actuation of limit switch 112. This count is converted into 
belt travel and, hence, thickness of the last bread slice. If the 
determined thickness of the last bread slice is more than 80 percent 
greater than the thickness entered by the operator using thumb wheel 
switch 114, then single revolution cutoff clutch 74 is again actuated to 
make one additional slice. 
At this point, a last push mode 218 is entered. The arm and knife drive 
turn off, and the brake solenoid 40B de-energizes, stopping the bread 
knife rotation. Then pusher 60 will advance past knife 24 to push the 
remainder of the loaf onto the outfeed table beneath cover 86. The 
operator will then lift cover 86 and remove the sliced bread. The operator 
can now return the heel holder 20 to its position closer to knife 24. 
Reclosing of door 86 will initiate a return mode 220 and enable pusher 60 
to return to its initial retracted position (FIG. 2) for receipt of the 
next loaf of bread in front of it. At any point, operation of the 
apparatus can be interrupted by pressing stop button switch 120. Further, 
opening any of the three covers at any time will deactuate power to the 
knife drive. A flow chart illustrating the detailed operation of control 
program 200 is appended to this specification as Appendix A and is 
intended to form an integral portion of the specification. 
In the illustrated embodiment, cutoff arm drive motor 70 is a one-eighth 
horsepower DC motor that operates from an input that varies from 0 to 90 
VDC. Stepper motor 104 is commercially available and is marketed by 
Oriental Motors under Model No. PH296-02GK with a six-to-one ratio gear, 
also marketed by Oriental Motors under Model No. 4GK6KA. Stepper motor 104 
produces one-sixth revolution through the gear reducer for each 200 pulses 
from controller 132, which represents one inch of travel of belt 98. The 
index speed of belt 98 is six inches per second at 800 pulses per second 
from controller 130. Microprocessor/ stepper driver includes a central 
processor unit, or CPU, 160 and optical isolator circuits 162a-162d for 
coupling inputs IN01-IN13 to CPU 160 (FIG. 10a). CPU 160 supplies a 
stepper driver circuit 164 with commands, with circuit 164 supplying step 
01-06 commands 166 to stepper motor 104 (FIG. 10b). CPU 160 drives relays 
outputs OUT 1-OUT 3 through a buffer circuit 166 and through relays 
168a-168d. CPU 160 drives transistor outputs OUT 5 and OUT 6 through a 
buffer circuit 170 and through overload devices 172a and 172b. In the 
illustrated embodiment, CPU 160 is a model 6800 microprocessor chip set 
marketed by Motorola, Inc. Stepper driver circuit 164 is marketed by 
Miquest Corp. under Model MI348. Optical isolator circuits 162a-162d and 
buffer circuits 166 and 170 are conventional devices. 
Although the invention is illustrated as implemented on a microprocessor 
control, it is adaptable to being implemented using a programmable logic 
controller and an intelligent stepper driver to directly actuate stepper 
motor 104. Such modification would be readily apparent to the skilled 
artisan. 
This novel apparatus can be installed in a small store, bakery, 
delicatessen, or the like, to enable slices of various thickness to be 
readily created from a loaf of unsliced bread, enabling a person to cut 
the bread to a standard one-half inch thickness, a deli one-quarter to 
three-eighths inch thickness, a garlic bread thickness of up to one inch, 
or as desired, simply by rotating thumb wheel 114 to the desired setting, 
placing the loaf of bread on the infeed table, closing cover 80, and 
engaging start button 118. The slicer knife 24 then repeatedly slices the 
loaf to the predetermined slice width until the loaf is totally sliced or 
until the operator stops the machine. Cover 86 is lifted and the sliced 
bread removed. 
The specific embodiment of the invention disclosed above could conceivably 
be modified in various ways within the scope of the inventive concept, to 
suit a particular situation. This preferred form of the invention is 
deemed illustrative, with it being intended that the invention is not to 
be limited to this specific embodiment depicted, but only by the scope of 
the appended claims and the reasonably equivalent structures to those 
defined therein.