EP0176579A1 - An apparatus for cutting a block of food into slices - Google Patents

Abstract

A cutting apparatus for cutting blocks (12) of meat or the like into slices comprises three rotary knives (20). These knives are driven for example by means of a planetary gear so that they rotate around their own axes and are moved simultaneously in a common plane along a circular path (32) beyond the free end of the block to cut. The use of the three rotary knives ensures a high production rate without increasing the overall dimensions of the apparatus, and the movements of the cutting knives do not create unbalanced forces of inertia. The cutting apparatus may include weighing means and pushing or sweeping means for automatically passing quantities of cut slices onto bread slices (17) which are successively transported along a conveyor for the purpose of produce open or closed sandwiches.

Description

AN APPARATUS FOR CUTTI NG A BLOCK OF FOOD I NTO SLI CES

The present invention relates of an apparatus for cutting a block of meat or another food block into slices .

US patent No. 3,867, 558 and published Swedish patent specification No. 419.307 disclose such a cutting apparatus comprising two ci rcular rotatable cutting knives arranged in a common plane. By means of a planetary gear each of these circular knives may be rotated about its axis, and the centers of the circular knives may simultaneously be moved along a circular path . When a block or column of meat is intermittently pushed along a path extending transversely to the cutting knives, a slice is cut from the block or column by each knife passing the path of movement on the block. When the slicing apparatus comprises two rotating knives, two slices are cut for each revolution of the cutting knives along the circular path of movement of the knives . It is understood that the rate of production of slices is proportional with the rotational speed of the rotating knives along the circular path of movement, but also proportional with the number of rotating knives used in the apparatus . Therefore, the above Swedish patent specification proposes use of four and even more circular knives .

The mutual spacings of the ci rcular knives must necessarily be sufficient to allow the block or column to be sliced to pass th rough these spacings of the knives . Therefore, if the number of knives is increased from two to four, or even to a higher number as proposed in the Swedish specification, it would be necessary either to reduce the diameter of the circular cutting knives, whereby the maximum cross sectional area of the block or column to be sliced would be decreased, or to increase the diameter of the circular path of movement of the cutting knives, whereby the overall dimensions of the apparatus and the peripheral speed of the cutting knives would be substantially increased . The present invention provides an apparatus of the above type allowing for a substantially increased production at a given rotational speed of the cutting knives along the circular path of movement, without increasing the overall dimensions of the apparatus .

Thus, the present invention provides an apparatus for cutting a block or column of meat or another food block into slices, said apparatus comprising th ree similar, rotatable, mutually uniformly spaced cutting knives having substantially circular cutting edges and being arranged sub- stantially in a common plane with their centers positioned on a cir¬ cular first path of movement, means for rotating each of said cutting knives about a center axis thereof and for simultaneously moving the centers of said uniformly spaced cutting knives along said circular first path of movement, and means for intermittently moving the free end of said block into the spaces between the cutting knives along a second path extending transversely to the cutting knives, whereby a slice is cut from said block by the cutting edge of each rotating knife for each revolution thereof along the circular first path of movement.

For a given rotational speed of the circular cutting knives along their circular first path of movement the increase of the number of cutting knives from two to three increases the rate of production by 50% without increasing the diameter of the circular area covered by the rotating circular knives, which means that the increase of the number of circular knives does not increase the overall dimensions of the apparatus . Furthermore, the use of three cutting knives does not create any imbalanced forces of inertia.

For a given diameter of the circular path of movement of the cutting knives, it is normally desired to choose the largest possible diameter of the cutting knives. This means that the circular cutting edges of the cutting knives must be closely spaced inside the circular first path of movement while the cutting edges are more widely spaced outside said first path of movement. Therefore, the said second path of movement along which the block or column of meat or food is pushed into the spacings between the cutting knives preferably intersects the said common plane of the knives outside the ci rcular first path of movement.

The direction of rotation of the circular cutting knives about thei r own axes may be different for the various knives and the direction of the movement of the circular knives along the circular path of move¬ ment may be chosen as desired . However, in the preferred embodiment of the apparatus according to the invention the rotating and moving means are adapted to move the ci rcular knives in the same direction along said fi rst path of movement as that in which each of the knives are rotated . When a slice is cut from the block the rotational movement and the movement along the circular first path of the cutting knife impart a momentum to the cut slice. When the di rection of the rotational movement and the direction of the movement along the ci rcular first path are the same, these two movements will impart such a momentum to the cut slice that it may be th rown to a desired position at a certain distance from the cutting knives .

The cutting apparatus according to the invention may have a slice receiving plate or platform for receiving the slices cut and pushing or sweeping means for pushing slices from said platform to another position, when a predetermined amount of slices has been collected on the platform. Cut slices may, for example, be thrown onto the receiving platform by the momentum imparted thereto due to the movement of the cutting knives . The pushing or sweeping means may, for example, be activated, when a predetermined number of slices has been collected on the receiving platform, and the slices, which have been passed to the said other position by the pushing or sweeping means may, for example, be packed .

I n a preferred embodiment of the apparatus according to the invention the receiving platform forms part of weighing means, and the said predetermined amount of slices being collected on the platform before the slices are pushed therefrom by the pushing or sweeping means may then be slices having a predetermined weight. When the cutting means is used for cutting very thin slices of meat (so-called shaved meat) , a relatively great number of which is used on a single open sandwich, the cutting apparatus may comprise a conveyor which is adapted to successively transport slices of bread which may have a layer of butter, margarine, or another kind of fat spread thereon, to the said other position . The pushing or sweeping means may then move the desired number of thin slices of meat from the receiving platform directly down onto the bread slices so as to produce open sandwiches which may then be further transported to another location . Thus, the cutting apparatus according to the in¬ vention may form part of a plant for automatically producing closed or open sandwiches . Due to its high production rate the cutting apparatus according to the invention is well suited for the said pur¬ pose, especially when a great number (for example about 20) of thin meat slices are used for each sandwich .

I n order to obtain automatic operation the cutting apparatus according to the invention may be provided with an electrical or electronic control circuit, which is adapted to control the function of the sweeping or pushing means in dependency of weighing signals from weighing means associated with said slice receiving platform so as to cause actuation of the pushing means when a slice of bread has been located in said other position and a predetermined weight of slices has been collected on the receiving platform .

The cutting apparatus may further comprise a grinding wheel which is positioned centrally in the circular first path of movement of the cutting knives so that the grinding wheel may be moved into simul¬ taneous contact with the cutting edges of all of the knives for grin¬ ding the cutting edges thereof. Thus, all of the cutting knives may be sharpened simultaneously by axially displacing the grinding wheel against the rotating knives, for example along a shaft which is arranged centrally in said circular path and which may, for example, form part of a planetary gear for rotating and moving the cutting knives . The invention will now be further described with reference to the drawings, wherein

Fig . 1 shows a side view of an embodiment of the cutting apparatus according to the invention, Fig . 2 diagrammatically illustrates the movements of the cutting knives of the apparatus in relation to a block of meat being cut into slices,

Fig . 3 is a partial sectional view diagrammatically showing the mechanism for driving the knives,

Fig . 4 is a plan view diagrammatically showing a conveyor belt for slices of bread and a sweeping mechanism for transferring cut slices of meat to the slices of bread,

Fig . 5 diagrammatically illustrates a mechanism for driving the sweeping mechanism,

Fig . 6 is a partial sectional view showing a grinding wheel and a moving mechanism therefor shown in an enlarged scale, and

Fig . 7 is a partial sectional view showing a bearing structu re for the grinding wheel shaft.

The cutting mechanism shown in Fig . 1 comprises a base or frame 10 defining a downwardly sloping su rface 11 defining a path of movement for a number of successive blocks 12, which may, for example, be blocks of meat or cheese. The apparatus also comprises a cutting unit 13 and a weighing unit 14, which are mounted on the frame 10. The frame or base 10 may be hollow and may comprise an electronic con¬ trol unit with a control panel 15 mounted in the frame wall . The apparatus also further comprises a conveyor unit 16 for successively moving buttered slices of bread 17 to a position opposite to the weighing unit 14. The frame 10 comprises a base plate 18 having adjustable foot members 19 mounted thereon .

As best shown in the diagrammatic illustrations of Figs . 2 and 3, the cutting unit 13 comprises th ree identical circular cutting knives 20 each mounted at one end of a shaft 21 . A planet gear 22 is mounted at the other end of each of the shafts 21 . All of the gears 22 associated with the cutting knives 20 are in engagement with the teeth of an outwardly toothed rim 24, which is fixed on a housing 23 of the cutting unit 13. The shafts 21 , which are common to the cut- ting knives and the planet gears 22, are rotatably mounted in bear¬ ings 25, which are fastened by means of a spider 26 to a driving shaft 27, which is journalled centrally in the housing 23. The bearings 25 are arranged at the same radial distance from the shaft 27 and are uniformly peripherally spaced around this shaft. The shaft 27 may be driven by means of an electric driving motor 28, which is mounted on the housing 23, and the shaft of the motor may be directly connected to the driving shaft 27 as in Fig . 1 . Alternatively, the motor shaft may be connected to the driving shaft 27 by means of pulleys 29 and 30 and a driving belt 31 as shown in Fig. 3.

When the motor 28 is energized so as to rotate the driving shaft 27, the spider 26 will be rotated by the shaft 27, whereby the shafts 21 of the cutting knives 20 are moved along a circular path 32 at a rate determined by the rotational speed of the electric motor 28. As the planet gears 22 mounted on the shafts 21 are in engagement with the teeth of the stationary toothed rim 24, the shafts 21 and the cutting knives 20 are forced to simultaneously rotate about their own axes at a rotational speed which is determined by the rotational speed of the driving shaft 27 and by the ratio between the diameters of the toothed rim 24 and each of the planet gears 22, respectively. When the centers of the cutting knives 20 are moved along their circular path 32, the knives successively pass the path of movement 11 of the blocks 12, where the radially outer parts of the cutting knives extend through an opening 33 formed in the housing 23 adjacent to said path . Each time one of the cutting knives 20 passes the meat block 12 a slice is cut from the free end of the lower block 12 being pushed along the path 11 as indicated in Fig. 2. A condition is that the block is advanced a distance corresponding to the desired thickness of the slice, each time one of the cutting knives has passed the block 12. The path of movement 11 may, for example, be defined between a pair of oppositely arranged roller coirveyors 34, and the desired stepwise forward movement of the blocks 12 may then be obtained, for example, by means of a spiked belt, not shown, which may be driven by a step motor 35 via a worm gear 36. As indicated by arrows in Fig . 2, the cutting knives 20 are prefer¬ ably rotated so that the direction of movement of their shafts 21 along the circular path 32 is the same as the direction of the rotational movement of the cutting knives about their own axes . Thereby a momentum is imparted to the slices cut from the block 12 so that they are thrown onto a supporting plate or platform 32 forming the "scale pan" of the weighing unit 14. As best shown in Figs . 4 and 5, the upper su rface of this supporting plate 37 has parallel grooves 38 formed as arcs of a circle defined therein , and the supporting plate 37 is connected to a weighing cell 40 by means of a rod 39.

As shown in Figs . 4 and 5, the supporting plate 37 cooperates with a rod-shaped sweeping or pushing member 41 having ridges or ribs, which are complementary to the grooves 38 defined in the supporting plate 37, formed on its lower side for engaging with these grooves . The pushing member 41 has two spaced bearings 42 each cooperating with a vertical pivot pin 43 formed on a driving disc 44. The pair of driving discs 44 are identical and each mounted on a shaft with a gear 45, and both of the gears 45 are driven by means of an inter¬ mediate gear 46, which are in tu rn driven by an electric motor or a step motor 47. This motor and the weighing cell 40 may be arranged within a housing 48 on which the shafts of the gears 45 and 46 are journalled . As best seen from Fig . 4, a simultaneous rotational movement of the two driving discs 44 th rough a single revolution causes the sweeping or pushing member 41 to be moved from a star- ting position along one side of the supporting plate 37 across the supporting plate so that a number of cut slices 49, which have been collected on the plate, are pushed onto a buttered slice of bread 17 which has been located adjacent to the plate on a conveyor belt 50 associated with the conveyor unit 16. Thereafter, the pushing member is moved backwards out of engagement with the supporting plate 37 and is returned to its starting position . This means that the retur¬ ning movement of the pushing member 41 does not prevent further cut slices 49 from being collected on the plate 37 at the same time.

The operation of the cutting apparatus and the transporting unit is controlled by means of the control circuit associated with the control panel 15. An operation sequence may be initiated by a pulse generated by a detector, when a slice of bread 17 is in position adjacent to the supporting plate 37 as shown in Fig . 4. Thereafter the control circuit causes the motor 47 to be energized as soon as a signal has been received from the weighing cell 40 indicating that the desired amount of meat slices has been collected on the supporting plate 37. The movement of the pushing or sweeping member 41 may be adjusted by means of microswitches 51 which cooperate with one of the driving discs 44.

The cutting apparatus also preferably comprises a grinding mechanism 52, which is common to all of the three circular knives 20. This grinding mechanism is shown in Figs . 2 and 3, but is shown more in detail in Figs . 6 and 7. The grinding mechanism 52 includes a grin¬ ding wheel 53, which is mounted on the driving shaft 27 arranged at the center of the circular path of the cutting knives 20. The rim of the grinding wheel 53 has a channel-shaped cross-section and com¬ prises a grinding flange 54 defining an inner oblique grinding surface 55, which may simultaneously Joe brought into engagement with the inner sides of the cutting edges 56 of all three rotating cutting knives 20. The grinding wheel 53 also has a guiding flange 57 with cut-outs at diametrically opposite positions . These cut-outs define sloping surfaces 58 for cooperating with corresponding sloping sur¬ faces 59 on a fork-shaped engagement member 60. This engagement member 60 is resiliently fastened to a carriage 62 by means of one or more screws 61 or other fastening members . The carriage 62 is com¬ posed by a plurality of parts which may, for example, be intercon¬ nected by means of screws 63. The carriage 62 is mounted on the front panel 64 of the housing 23 of the cutting unit in such a manner that the carriage may be displaced between an advanced position in which the legs of the fork-shaped engagment member 60 is moved into the channel of the grinding wheel and a retracted position in which the legs of the engagement member are out of engagement with the channel of the grinding wheel, while the sloping surfaces 58 and 59 are still in mutual abutting relationship as shown in Fig. 6. A handle 65 fastened to the carriage 62 extends through a cut-out in the front panel 64, and a tension spring 67 which is fastened to the carriage 62 and to the front panel 64, respectively, retains the carriage in its retracted position shown in Fig . 6. The grinding wheel 53, which is kept stationary on the rotating shaft 27 by the engagement member 60 abuts a spring ring 68' mounted on the shaft 27, which retains the carriage 62 is in its retracted position .

When it is desi red to grind the rotating cutting knives 20 the handle 65 is moved manually towards the shaft 27, whereby the carriage 62 and the engaging member 60 mounted thereon are moved to the advanced position of the carriage against the bias of the spring 67. The interengagement of the sloping surfaces 58 and 59 will then cause the oblique grinding surfaces 55 of the grinding wheel 53 to be pressed in engagement with the cutting edges of all three of the cutting knives 20. As the cutting knives are rotated, the cutting edge of each of the knives will be ground at an angle corresponding to the slope or angle of the grinding surface 55. When the cutting knives have been suitably sharpened, the handle 65 is released, the spring 67 automatically returns the carriage to its retracted position, whereby the grinding su rface 55 of the grinding wheel 53 is again moved out of engagement with the knives 20. A spring blade 83 ensures that the grinding pressure is independent of the manual pressure exerted .

The end of the driving shaft 27 on which the grinding wheel 53 is mounted is rotatably supported in a special bearing 68 which renders it possible to replace the grinding wheel 53 quite easily. A conical bore 69 is formed in the free end of the driving shaft 27, and at the bottom of this bore a th readed bore 70 is formed . A shaft extension 71 has an end portion 72 with a frustoconical outer surface, which is complementary to the inner surface of the conical bore 69, and this end portion 72 is received in the bore 69 and retained therein by means of a screw 73 extending th rough a central bore formed in the shaft extension 71 , and the screw 73 is screwed into the threaded bore 70. The radially inner part of the bearing 74, which may, for example, be a ball bearing or a roller bearing, is arranged between a flange 75 formed on the shaft extension 71 and a spring ring 76 mounted >on said extension . The radially outer part of the bearing 74 is received in a bearing housing 77 having an outer flange 78, which is fastened by means of screws 79 (only one Is shown in Fig. 7) to an annular mounting part 80, which is fastened to the front panel 64 by means of screws 81 (only one is shown in Fig. 7) . The bearing housing 77 has a conical, peripheral outer surface engaging with a complementary conical inner surface formed in the annular mounting portion 80.

When the grinding wheel 53 is to be replaced the screws 79 which retain the bearing housing 77 are removed, and thereafter the screw 73 is unscrewed . As shown in Fig . 7, the outer end of the central bore of the shaft extension 71 has a somewhat increased diameter, and an internal th read 82 is formed in this part of the bore. When the screw 73 has been removed, a screw of the type- being threaded adjacent to the screw head and having an unthreaded shaft portion extending from the threaded portion, may be screwed into the central bore of the shaft extension . The free end of the unthreaded shaft of this screw will then engage with the bottom of the threaded bore 70, whereby the shaft extension may be released from the shaft 27. The bearing housing 77 with the bearing 74 and the shaft extension 71 will now be removed, and the grinding wheel 73 may then be replaced by a new one, whereafter the shaft extension, the bearing, and the bearing housing may be mounted again .

EXAMPLE

A block of ham having a square cross-section of 100x100 mm is cut into slices each having a thickness of about 1/4 mm by means of a cutting apparatus as that shown in the drawings. The sweeping or pushing member 41 is activated when ham slices with a total weight of about 80 g have been collected on the supporting plate or the receiving platform 37, which means about 20 thin slices. The conveyor unit 16 transports a slice of bread to the weighing unit each 1 .5 seconds, which means that the cutting apparatus is able to cut about 20 slices of ham in that period of time. Thus, in every minute the apparatus is able to produce about 40 open sandwiches each covered by about 20 slices of ham each having a thickness of about 1/4 mm. While the apparatus has been described above specifically with reference to cutting slices of blocks of meat and cheese, it should be understood that the cutting apparatus according to the invention could also be used for slicing other kinds of food products such as bread . Furthermore, the cutting apparatus could also be used for slicing blocks of other products, which need not necesssarily be food products .

Claims

1 . An apparatus for cutting a block of meat or another food block into slices, said apparatus comprising three similar, rotatable, mutually uniformly spaced cutting knives having substantially circular cutting edges and being arranged sub¬ stantially in a common plane with their centers positioned on a cir¬ cular first path of movement, means for rotating each of said cutting knives about a center axis thereof and for simultaneously moving the centers of said uniformly spaced cutting knives along said circular first path of movement, and means for intermittently moving the free end of said block into the spaces between the cutting knives along a second path extending transversely to the cutting knives, whereby a slice is cut from said block by the cutting edge of each rotating knife for each revolution thereof along the circular first path of movement.

2. An apparatus according to claim 1 , wherein the circular cutting edges of the cutting knives are closely spaced inside said circular path of movement.

3. An apparatus according to claim 2, wherein said second path of movement intersects said common plane outside said circular first path of movement.

4. An apparatus according to any of the claims 1 -3, wherein said rotating and moving means comprise a planetary gear.

5. An apparatus according to any of the claims 1 -4, wherein said rotating and moving means are adapted to rotate each of the cutting knives in the same direction as that in which said knives are moved along said circular first path of movement.

6. An apparatus according to any of the claims 1 -5 and further comprising a slice receiving platform for receiving cut slices and pushing means for pushing slices from said platform to another position , when a predetermined amount of slices has been collected on the platform.

7. An apparatus according to claim 6, wherein said pushing means comprises a rod-like member and a moving mechanism therefor for synch roneously moving each of a pair of axially spaced points of said rod member along a circular path .

8. An apparatus according to claim 6 or 7, and further comprising a conveyor for successively moving slices of bread to said other position .

9. An apparatus according to claim 8 and further comprising an electrical control ci rcuit for controlling the function of the pushing means in dependency of weighing signals from weighing means associated with said slice receiving platform so as to cause actuation of the pushing means, when a slice of bread has been located in said other position and a predetermined weight of slices has been collected on the receiving platform.

10. An apparatus according to any of the claims 1 -9, and further comprising a grinding wheel, which is positioned centrally of said circular first path of movement so that it may be moved into simultaneous contact with the cutting edges of all of the cutting knives for grinding the cutting edges thereof.