Device for cutting loaves and the like
United States Patent [1 1 Moorman i 1 DEVICE FOR CUTTING LOAVES AND THE LIKE [75] inventor: Eduard Otto Moorman, Leiderdorp,  
 Netherlands [731 Assignees: B.V. Haagse Bakkerijmachineiabriek; Arnold Kalmeijer, both of The Hague Netherlands [22] Filed: Oct. 17, 1973 [21] App]. No; 407,153  
 [30] Foreign Application Priority Data Oct 3l. I972 Netherlands 72l4736 [52] US. Cl 83/431; 83/751 [5 l] Int. Cl B26d 7/06; B23d 51/00; 826d 4/10 [58] Field of Search 83/751, 431,82]  
 I56| References Cited UNlTED STATES PATENTS 1,976,33l l0/l934 Criner 83/751 2.095.620 l0/l937 Tuthill et al. 83/75] Apr. 8, 1975 Primary E.ruminer-Willie G. Abercrombie Attorney, Agent, or FirmSnyder, Brown and Ramik 57 ABSTRACT The invention relates to a device for cutting a loaf into slices, comprising at least one group of parallel knives set in a frame, a motor causing the frame or each frame of the group of knives to perform a reciprocatory cutting movement through a crank and connecting rod transmission, a chassis supporting the motor and the frame or each frame and actuating means for producing a relative movement between the object to be cut and the frame of a group of knives, in which device the cutting speed is considerably higher as compared with that of known constructions, so that it is now possible to cut a loaf without the need for lubricating the knives, as according to the invention the frame is rigidly fastened to the connecting rod and is coupled via a straight guide with the chassis near its natural centre of rotation determined by the moment of inertia of the moving mass.  
 16 Claims, 4 Drawing Figures PATENTEHAPR ems 1875.840 saazneurz Willa/I114 l DEVICE FOR CUTTING LOAVES AND THE LIKE The invention relates to a device for cutting a loaf or a similar object into slices, comprising at least one group of parallel knives set in a frame, a motor causing the frame or each frame of the group of knives to perform a reciprocatory cutting movement through a crank and connecting rod transmission, a chassis supporting the motor and the frame or each frame and actuating means for producing a relative movement between the object to be cut and the frame of a group of knives.  
  Many embodiments of devices of the kind set forth are commercially known, in which the frame ofa group of knives is coupled with the chassis via a parallel guide or is reciprocated along a guide path. In both cases the drive between the driving motor and the frame is formed by at least one connecting rod coupled by means of hinges. All these known constructions have the disadvantage that they can operate with only comparatively low speeds due to the large number of hinges in the transmission or in the suspension. If the speed were raised, wear would increase out of proportion. Moreover, balancing out of the known construction is a complicated, time-consuming and hence expensive operation.  
  The invention has for its object to provide a device for cutting, in particular, loaves, in which the cutting speed is considerably higher as compared with that of the known construction, so that it is now possible to cut a loaf without the need for lubricating the knives. With low speeds lubrication is required because otherwise the bread will stick to the sides of the knives. It is furthermore possible to cut warm loaves, that is to say immediately after having left the oven.  
  For this purpose the invention provides a device in which the frame is rigidly fastened to the connecting rod and is coupled via a straight guide with the chassis near its natural centre of rotation determined by the moment of inertia of the moving mass.  
  Since the frame is rigidly secured to the connecting rod there are no disadvantageous hinges. Consequently, the connecting rod with the frame of the group of knives may be considered to form a unit, which is directly moved by the crank or the eccentric of the mo tor. The invention is further based on the recognition of the fact that, when a body is subjected to a shock at an arbitrary point lying outside its centre ofgravity, this body will not start turning about its centre of gravity but will turn about its natural centre of rotation determined by its moment of inertia. When a framework with a connecting rod as used in the device embodying the invention is driven by a crank, the end of the connecting rod will describe a circle which can be resolved in two directions i.e. one going through the centre of gravity of said unit and one at right angles thereto. The direction of movement passing through the centre of gravity may be considered to form the reciprocatory cutting movement of the knives and the movement at right angles thereto may be considered to be a reciprocatory, rotary movement or an oscillatory movement around a natural centre of rotation to be determined empirically or by calculation for each unit. The latter centre will perform a rectilinear movement, it is true, owing to the upward and downward cutting motion, but this has the great advantage that with any suspension to be arranged at said place not any reactive force directed transversely of the cutting motion will occur. The lack of any reactive force implies a practically in destructible suspension. It will be obvious that balancing out of the movable parts is restricted to balancing of the crank mechanism or the eccentric mechanism on the driving shaft of the motor only. By using a frictionless pivotable shape of leaf spring as a suspension at the natural centre of rotation of the frame, the blade of the spring extending at right angles to the cutting motion, a further improved vibration-free and noiseless device is obtained since at this place any play is lacking.  
  According to the invention in a preferred embodiment of the device comprising two vertical frames arranged side by side and having their groups of knives interengaging one another so that the knives of one group alternate side by side with those of the other group, the cutting movements of the two groups being opposite each other and the actuating means comprising a pressure member formed by a group of plates uniformly spaced and adapted to move in between the knives, the mass of the movable parts is distributed so that the leaf spring extends below the horizontal plane going through the path of movement of the pressure member, whilst at least some of the plates of the pressure member have a horizontal, sharp edge on the side facing the knives.  
  Owing to the aforesaid disposition of the leaf spring the knives in their frame not only perform an upward and downward cutting motion, but also a forward rocking motion viewed in the direction to the object to be cut. A great advantage is thus obtained in that the pres sure plate employed in the known devices of this kind for holding the loaf to be sliced in place can be dispensed with. During the downward cutting motion of the knife the latter penetrates more deeply into the loaf, whereas during the upward motion the knife disengages itself from the cut made. Thus the function of the pressure plate above the loaf is taken over by the knives themselves.  
  Since with some types of loaf the forces produced might cause the loaf to turn about its longitudinal axis, it is preferred to provide each plate of a pressure member with a horizontal, projecting rim in order to counteract said turn.  
  Owing to the high cutting speed it is now also possible to slice freshly baked loaves just leaving the oven. This involves the problem that warm loaves and cold loaves have to be cut with different initiating forces in order to obtain an optimum cutting effect. Moreover, the initiating force varies with the kind of loaf to be sliced.  
  For this purpose in accordance with the invention the actuating means comprise furthermore a reversible, first motor running with uniform speed for moving the pressure member towards and back from the knife frame and at least one second motor exerting the initiating force required for cutting on the pressure member.  
  Owing to the use of two motors for moving the pressure member the loaf can be fed to the knife frame with a controlled speed. The application of the loaf during the cutting operation is obtained from the second motor, which may be adjustable for varying the force of application. Various embodiments may be designed for obtaining the relative coupling of two motors, which is illustrated in the following specification of the Figures.  
  This specification is made with reference to a drawing in which FIG. I is a sectional view of a loaf cutting machine taken on the line ll in FIG. 2,  
  FIG. 2 is a sectional view of the same device as shown in FIG. 1 taken on the line II-II in FIG. 1,  
  FIG. 3 is an elevation of the frames with the associated knife groups, illustrating the movement of the knives during the cutting operation,  
  FIG. 4 shows schematically a different embodiment of the actuating means.  
  The embodiment of the cutting device in accordance with the invention shown in the Figures is the generally employed standing model of a loaf slicing machine. This kind of cutting device uses two groups of knives l and 2, each group being set in its own frame 3 and 4 respectively. Each framework 3, 4 is coupled through a rigidly fastened connecting rod 5, 6 respectively with the crank or an eccentric 7 and 8 respectively on the output shaft of an electric motor 9. The cranks 7 and 8 extend in opposite directions so that when the cranks are rotated by the electric motor 9 the frameworks 3 and 4 perform relatively opposite movements.  
  Each group 1 and 2 comprises a plurality of parallel, vertical knives. Each knife is formed by an elongated, thin and narrow blade, the lower end of which is fastened through a yoke 10 to the lower beam of the associated framework. whereas the top end is suspended in a tiltable yoke ll to the top beam of the framework. The yoke ll is engaged at its other end by a compression spring 12 so that the knife blade is subjected to tensile stress. This yoke suspension permits of arranging the knives of the two groups and 2 alternately side by side, as will be appreciated from FIGS. 1 and 2.  
  Each framework 3, 4 is secured by its lower beam to the center of a leaf spring 13, which extends along the plane going through the framework and the ends of which bear on a horizontal rectangle of beams 14, which encloses the two frameworks 1 and 2. The rectangle of beams 14 bears on beams of the chassis 16 through vibration absorbers 15. The leaf spring 13 (see FIG. 1) has a shape such that it allows for a vertical deflection of its center determined by the crank 7 and 8 respectively.  
  The loaf to be sliced, indicated by the broken line 17 in FIG. 2, bears on a plate-shaped support 18, which forms part of the chassis. Above and along this plate 18 a pressure member 19 is displaceable perpendicularly to the plane going through the frameworks 3 and 4. The pressure member is formed by a plurality of vertical plates spaced apart so that they can move in between the knives of the groups I and 2.  
  The pressure member 19 is fastened to a slide 20, which is movable along guide bars 21 in the chassisv The slide 20 comprises two vertical posts terminating at the top end in eyelets fitting around the guide bars 21 and interconnected at their lower ends by a horizontal beam. The slide 20 with the pressure member 19 thus forms a rectangular structure around the loaf carrier 18. The horizontal beam of the slide 20 is secured at two places to a flexible pulling element 22, which may be a chain, a rope or a cable. This pulling element 22 is coupled at its free end to a weight 23 in the form of horizontal beam and which operates as a second motor. The ends of the weight beam 23 are provided with rollers 24, each of which travels along the associated guide 25. The guides 25 have a U-shaped cross section, the open ends facing each other. The top ends of these guides are rigidly secured to a shaft 26, which can be turned with respect to the chassis by means of a lever 27, as is indicated in FIG. 2 by the broken line 28.  
  The other end of the pulling member 22 is first passed over a reversing roller 29 and then over the driving roller 30 and is finally coupled with a counter weight 31. The driving roller 30 is driven via a gear box 32 by a reversible first motor 33 rotating with a uniform speed.  
  FIG. 4 shows a different embodiment of the actuating means. The pressure member 29 is again connected with its slide to a flexible pulling element, the free ends of which are secured to a spring 38, so that the spring and the flexible pulling element constitute an endless unit passed around two reversing rollers. The hindmost reversing roller, viewed in the direction of application of the pressure member 29, is driven via a gear box 32 by a reversible, first motor 33 rotating with a uniform speed. The spring 38 should be considered to form here in a second motor.  
 The device operates as follows.  
  When the motor 9 rotates, the cranks 7 and 8 will rotate rapidly so that also the lower ends of the connecting rods 5 and 6 perform a rapid rotary movement. By a correct distribution of the mass of each unit, that is to say, the knife group 1 and 2, the framework 2 and 4 respectively, the connecting rod 5 and 6 respectively, the natural centre of rotation determined by the moments of inertia of the components will be located at the level of the top surface of the lower beam of the framework 3 and 4 respectively. This point will perform only a rectilinear, vertical movement so that it constitutes the coupling point of the leaf spring 13 with the framework.  
  The knives themselves will perform not only a straight upward and downward movement, but also a rocking movement, which is illustrated in FIG. 3 on an enlarged scale. From this Figure it will be apparent that the lower ends of the knives located substantially near the point of suspension at the leaf spring 13 perform a straight upward and downward movement, whilst the top ends of the knives perform, in addition, a horizontal reciprocatory movement. The top ends of the knives describe an elliptic path designated in FIG. 3 by 34 and slightly distorted for a better illustration of the cutting movement of the knives. The cranks of the motor rotate in directions such that during the downward movement the knives cut the loaf and withdraw during the upward movement and disengage themselves from the slice made. This mode of cutting has the advantage that a pressure plate 37 shown in broken lines in FIG. 3 is no longer required for holding a loaf during the slicing operation on the carrier 18. The knives themselves perform the function, since the loaf is constantly urged downwards during the cutting operation, that is to say onto the carrier 18.  
  The loaf itself, however, is subjected, particularly at the beginning, to a rotational movement due to the cut ting forces (see the arrow 35 in the loaf). In order to counteract this movement, the front sides of the plates of the pressure member 19 are provided with sharp, projecting rims 36.  
  The loaf is fed to the groups of knives and urged across them as follows.  
  Prior to the slicing operation the first motor 33 is rotated in one direction to raise the weight 23 and move the pressure member 19 away from the knives into the position shown in FIG. 2. After the loaf 17 is placed on the carrier 18 by hand or by other suitable means, the motor 33 is rotated in the opposite direction so that the pulling member 22 is permitted to move the slide towards the knives under the action of the weight 23. The speed of this movement depends upon the uniform speed imparted by the motor 33 via the gear wheel transmission to the pulling member 22. This speed is chosen so that the loaf will engage against the knives in controlled manner and without shocks.  
  Once the load engages the knives, the speed of passage of the loaf through the groups of knives l and 2 is determined by the resistance put up by the loaf to the knives. Since the speed of passage will be lower than the speed of supply of the loaf, the motor 33, rotating with uniform speed, will slacken the left-hand part of the pulling member 22. Thus the pressure of the loaf to be sliced on the groups of knives l and 2 is completely determined by the vertical component of the force of gravity of the weight 23. The tension of the pulling member 22 between the weight 23 and the slide can be adjusted by arranging the guide paths 25 of the weight 23 at an angle to the vertical plane. In this way the device can completely match the kinds of loaf to be sliced and also to warm or cold loaves. After the loaf has been cut and delivered on the right-hand side of the groups of knives l and 2 (see FIG. 2), the pressure member 19 will extend across the knife groups and the slide 20 will actuate a stop which causes the reversal of the direc tion of rotation of the motor 33 so that the pressure member 19 is moved back with uniform speed. Then the cycle depicted above can be repeated.  
  If the pressure member 19 is started by the actuating means shown in FIG. 4, the motor 33 will initially move the pressure member with uniform speed to the right in FIG. 4 until the loaf 17 comes into contact with the knife groups 1 and 2. During the cutting operation the motor 33 continues rotating with uniform speed. The pressure member 29, however, will move to the right more slowly so that the part of the flexible pulling member located behind the slide of the pressure member will be slackened. The motor 33 energizes the spring 38 up to a given value depending upon the resistance experienced by the knives in the loaf. The actuating means can be adjusted to warm or cold loaf, for example, by using two or more flexible pulling elements with the associated springs, each of which can be separately driven by the motor 33. The properties of the springs 38 may differ from each other. In this embodiment the flexible pulling element is preferably formed by a chain in order to obtain a slip-free transmission between the reversing roller and the pulling element.  
  It will be obvious that the invention is not restricted to the embodiments described above and that other cutting machines for other objects or machines comprising horizontal groups of knives lie within the scope of the invention. It may be imagined, for example, that the motor 33 in the embodiment shown in FIG. 1 drives the wheel 26 instead ofdriving the wheel 30 of the pulling element 22, in which a switchable coupling is included between the wheel 26 and the motor 33.  
 What is claimed:  
  1. A device for cutting loaves or similar objects into slices comprising at least one group of parallel knives set in a frame, a motor causing the frame and said group of knives through a crank and connecting rod transmission to perform a reciprocatory cutting movement, a chassis supporting the motor and the frame and actuating means for starting a relative movement of the object to be cut and the knife group frame, said frame being rigidly secured to the connecting rod and being coupled with the chassis via a straight guide near its natural center of rotation determined by the moment of inertia of the moving mass.  
  2. A device as claimed in claim 1 wherein the straight guide is formed by at least one leaf spring extending between said frame and the chassis, said spring being substantially perpendicular to the cutting movement.  
  3. A device as claimed in claim 2 including a second frame and group of knives, the two knife groups being interengaged so that the knives of one group alternate side by side with those of the other group, the cutting movements of the two groups being in opposite directions, the actuating means comprising a pressure member formed by a group of uniformly spaced plates adapted to move in between the knives, the mass of the movable parts being distributed so that the leaf spring extends below the horizontal plane going through the path of movement of the pressure member and at least some of the plates have a horizontal, sharp rim on the side facing the knives.  
  4. A device as claimed in claim 2 wherein the leaf spring is coupled with the frame at its centre and bears on the chassis at its ends.  
  5. A device as claimed claim 1 wherein the actuating means comprise a reversible first motor operating with uniform speed for moving the pressure member towards and away from said knives and at least one second motor exerting the actuating force required for cutting on the pressure member.  
  6. A device as claimed in claim 5 wherein in that the first motor and the second motor are coupled via a flexible pulling element with the pressure member, the second motor being formed by a weight adapted to move along a guide, which is adjustable in a vertical plane at an angle.  
  7. A device as claimed in claim 5 wherein the second motor is formed by a spring fastened between the ends of a flexible pulling element passed around two reversing rollers, whilst the first motor drives the hindmost reversing roller, viewed in the starting direction of the pressure member.  
  8. A device as claimed in claim 3 characterized wherein the leaf spring is coupled with the frame at its center and bears on the chassis at its ends.  
  9. A device as claimed in claim 2 wherein the actuating means comprise a reversible first motor operating with uniform speed for moving the pressure member towards and away from said knives and at least one second motor exerting the actuating force required for cutting on the pressure member.  
  10. A device as claimed in claim 9 wherein the first motor and the second motor are coupled via a flexible pulling element with the pressure member, the second motor being formed by a weight adapted to move along a guide, which is adjustable in a vertical plane at an angle.  
  11. A device as claimed in claim 5 wherein the second motor is formed by a spring fastened between the ends of a flexible pulling element passed around two reversing rollers, while the first motor drives the hindmost reversing roller, viewed in the starting direction of the pressure member.  
  12. A device as claimed in claim 3 wherein the actuating means comprise a reversible first motor operating with uniform speed for moving the pressure member towards and away from said knives and at least one second motor exerting the actuating force required for cutting on the pressure member.  
  13. A device as claimed in claim 12 wherein the first motor and the second motor are coupled via a flexible pullimg element with the pressure member, the second motor being formed by a weight adapted to move along a guide, which is adjustable in a vertical plane at an angle.  
  14. A device as claimed in claim 12 wherein the second motor is formed by a spring fastened between the ends of a flexible pulling element passed around two reversing rollers. while the first motor drives the hindmost reversing roller, viewed in the starting direction of the pressure member.  
  15. A device for cutting loaves or similar objects into slices comprising, in combination:  
 a chassis having drive means mounted thereon and including an eccentric rotating in an orbital path, and feed means for travelling an object to be sliced along a given path;  
 at least one elongate frame, a group of parallel knives carried by said frame adjacent one end thereof and posititioned to engage and slice an object travelling along said given path, and attachment means connecting an intermediate portion of said frame to said chassis for combined oscillatory and reciprocating motion with respect thereto, the other end of said frame opposite said one end being engaged with said eccentric to follow said orbital path; and  
 said eccentric being disposed to orbit about an axis offset from but transverse with respect to said given path and in a direction of rotation so that said one end of the frame describes an elliptical path with said knives sweeping alternately toward said given path in opposition to the direction of object movement and away from said given path in the direction of object movement.  
  16. A device as defined in claim 15 wherein said feed means includes an object-engaging member, flexible means attached to said object-engaging member, a reversible motor and means connecting said reversible motor to said flexible means for tensioning a portion of said flexible means to move said object-engaging member away from said knives when the motor is operated in one direction and for paying out said portion of the flexible means when the motor is operated in the opposite direction, and means for exerting tension on another portion of said flexible means to press an object against said knives during operation of said motor in said opposite direction.  
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