GB2336762A - Cutting apparatus - Google Patents

Abstract

Apparatus for cutting soft products such as cheese, the apparatus including a cutting tool (2) for cutting the product, for example a cutter wire, thread, knife, blade or the like, a tensioning device (6) for tensioning the cutting tool (2), the device (6) being connected to the tool (2) and being operable by a compressed fluid, a supply (13, 14, 15) of compressed fluid for actuating the tensioning device (6), and a controller (20) for controlling operation of the apparatus. Pressure monitors (18, 19) monitor the pressure applied by the compressed fluid, and thereby the tension applied to the cutting tool (2) by the tensioning device (6), changes in pressure detected by the monitors (18, 19) sending signals to the controller (20) thereby enabling the apparatus to be stopped automatically if the cutting tool (2) breaks.

Description

2336762 - 1 Cutting Apparatus This invention concerns cutting apparatus

and in particular such apparatus which uses tensioned cutting tools, for example wires, threads, knives, blades and the like, to effect cutting of materials.

Many industrial processes rely on the use of arrays of tensioned cutting tools to cut relatively soft products such as cheese, wet clay, etc, simultaneously into a number of pieces, the cutting tools used in these processes usually being held under tension using simple mechanical means such as nuts and bolts, and in some cases springs.

From time to time one or more of the individual tools in these arrays, for example individual wires, threads, knives, blades or the like break. However, although the breakage is indicated by the emergence of uncut product, it can take time for operatives to notice that this has taken place. For example, it may not be until uncut product reaches a later stage in the process, such as packaging in the case of cheese. Breakage of the cutting 2 tool therefore not only leads to an interruption of production, in some cases it can lead to a loss of product.

Electrical systems have been proposed hitherto for indicating the failure of cutting tools in cheese cutting machines. However, although they can indicate breakages, these systems do not indicate losses of tension which can also lead to impaired cutting and possibly damaged product.

In order to minimise the time taken to replace individual broken cutting tools it has been common practice to mount arrays of them on a frame, and then to change the whole frame when one of the tools breaks. Although this can enable the time taken to effect the replacement to be reduced compared with replacing the broken tool in situ, it requires a supply of spare frames with pre-tensioned tools, and this can be expensive. Furthermore, there is still the problem that no indication is given when a cutting tool breaks or even improperly tensioned.

According to the present invention there is provided apparatus for cutting soft products, the apparatus comprising:- a) at least one cutting tool for cutting the said product; b) tensioning means for tensioning the said at least one cutting tool, the tensioning means being connected to the said tool and being operable by a compressed fluid; c) pressuring means for providing a supply of compressed fluid to the tensioning means; and d) pressure monitoring means for monitoring the pressure applied by the pressuring means and thereby the tension applied to the at least one cutting tool by the tensioning means.

Although apparatus in accordance with the present invention can have a single cutting tool, it will usually include a plurality of cutting tools and this can enable the soft product to be cut into a plurality pieces in one pass through the apparatus.

The compressed fluid used to operate the tensioning means, for example pistons or diaphragms working in cylinders, can be air or another gas or it can be a liquid.

When the apparatus includes a plurality of cutting tools, for example a plurality of cutter wires, threads or knives, a single pressuring means can be used to provide compressed fluid for all of the tensioning means associated with the individual tools. However, one or more of a plurality of cutting tools can be provided with separate tensioning means, thereby enabling individual tools to be tensioned independently of the others.

Apparatus in accordance with the present invention preferably includes pressure sensing means which senses the tension in the at least one cutting tool created by the pressuring means and stops the feed of product to be cut by the apparatus when the detected pressure exceeds or falls below predetermined maxima and minima, respectively.

The cutting tools are preferably cutter wires, threads, knives blades or the like.

An embodiment of apparatus in accordance with the present invention will now be described with reference to the accompanying diagrammatic drawings in which:- Figure 1 is a schematic representation of a portion of a cutter frame and associated control mechanism of cutting apparatus in accordance with the present invention; Figure 2 shows an alternative means for attaching cutting tools to the frame of Figure 1; and 4 Figures 3a-d show a number of alternative mechanisms for tensioning the cutting tools of Figures 1 and 2.

The embodiment illustrated in Figure 1 includes a frame or chassis with an upper part 1 and a lower part 1'. A plurality of cutting tools 2 in the form of cutter wires, threads or knives is disposed between the upper parts 1 and 1' of the frame or chassis, a loop 3 in the upper end of each wire being located on a pin 4 on the upper part 1 of the frame or chassis and a loop 5 in the lower end if each wire 2 being connected to the lower part 1' of the frame or chassis via one of a plurality of pneumatically operable actuators 6.

Each of the actuators 6 consists of a piston 11 which is movable in a cylinder 12, the actuators 6 being connected to the lower part 1' of the frame or chassis. The pistons 11 are connected to respective wires 2, and actuation of the pistons 11 in the cylinders 12 can be used to tension the wires 2 as described herein.

Actuation of the pistons 11 is effected using compressed air from a compressor 13, the pressure of the air from the compressor 13 being regulated by a pressure regulator 14. Air from the regulator 14 is then fed to the high pressure sides of the pistons 11 in the cylinders 12 via an on/off valve 15, a main conduit 16 and a series of conduits 16', this serving to tension all of the wires 2. The low pressure sides of the actuators 6 are connected to each other by a series of conduits 17 and to the on/off valve 15 via a conduit 17'.

:i The pressure of the compressed air in the conduit 16 is monitored by a low pressure monitor 18 and also by a high pressure monitor 19 which are connected by control lines 22 and 21 respectively to a controller 20. The controller 20 then controls the valve 15 using a control line 23 in response either to low pressure being detected by the low pressure monitor 18 or to high pressure being detected by the high pressure monitor 19. The valve 15 is either opened to allow compressed air to enter - the conduits 16 and 16', compressed air entering the conduits 16 and 16' forcing the pistons 11 of the actuators 6 downwardly in the cylinders 12, thereby tensioning all of the wires 2.

The pressure of the air in the conduits 16 and 16' rises and it eventually reaches a value which brings the wires 2 to the desired tension under the control of the pressure regulator 14.

The valve 15 is then closed to cut off the supply of compressed air from the compressor 13 and the regulator 14 whilst also maintaining the pressure in the conduits 16 and 16'. Provided there are no leaks in the system, all of the wires 2 will remain under tension. However, if one of them breaks, the pressure in the conduits 16 and 16' will fall rapidly with the result that the low pressure monitor 18 will provide a signal to the controller 20 along the line 22 which in turn provides a signal along a line 24 for automatically stopping the feed of product being fed to the cutter wires 2.

The apparatus preferably includes means which automatically re-tensions the cutting tools 2 after each cutting cycle, for example between cutting successive blocks of cheese fed to it.

As will be appreciated, rather than compressed air, a pressurised hydraulic fluid can be used in the conduits 16 and 16' to actuate the pistons 11, and the pressurised fluid can itself be pressurised by a source of compressed air or by a hydraulic pump. Alternatively, the actuators 6 can use a diaphragm rather than a piston to tension the cutting tools 2 as a result of differences of pressure across the diaphragm. It is also possible to use a spring return mechanism to bias the pistons 11 upwardly as shown in Fig. 1, and in this case the low pressure conduits 17 and 17' can be omitted. Spring return mechanisms can also be used with actuators which use diaphragms rather than pistons.

6 - As will also be appreciated, different tensions can imparted to different cutting tools 2, for example by using pistons and cylinders of different diameters.

Referring to Figure 2, instead of using a separate actuator 6 for each cutting tool 2, as is shown in Figure 1, one actuator 6 can be used to tension more than one tool 2, the actuator 6 being controlled as described with reference to Figure 1.

As a further alternative, separate on/off valves 15 and actuators 6 can be used for each cutting tool 2. Each actuator 6 can still be fed with compressed fluid from a common source but each actuator 6 will then need to be controlled independently of the others by controlling the pressure in the high and low pressure conduits connected to each actuator. For example, the tension can be increased in a particular cutting tool which has become slack, or different tensions can be applied according to the position or type of tool being used. A single broken or stretched tool can then be made to give an alarm or stop the cutting machine.

If a cutting tool 2 breaks, pressure in the conduits 16 and 16' will in general fall, thereby triggering the low pressure sensor 18 which in turn sends a signal via the line 22 to the controller 20 which stops the cutting machine by sending a signal along the line 24. The broken tool can then be replaced by releasing the pressure in the conduits 16 and 16' using the on/off valve 15, moving the piston 11 associated with the broken tool 2 manually to enable a new tool to be located between the upper and lower parts 1 and 11 of the frame or chassis of the machine, and thereafter re-pressurising the conduits 16 and 161, thereby causing the pistons 11 to tension the tools 2. Thus a number of individual tools 2 can be tensioned simultaneously or individually, depending on the construction of the apparatus.

In some instances, particularly when product being cut by the apparatus is travelling at high speed and the cutting tools are thereby placed under high tension, the breakage of a cutting 7 - tool may not result in a sufficient drop in pressure in the conduits 16 and 16' to actuate the low pressure sensor 18 even if the piston 11 of the associated actuator 6 is moved fully downwardly within the cylinder 12 as a result of the pressure in the system. In order to stop the cutting apparatus in such circumstances the actuators 6 each have sensors 7 which send an appropriate signal to the controller 20 when the piston 11 of the actuator 6 passes a position it would not normally take up during normal operation of the apparatus. The lines by which the sensors 7 are connected to the controller 20 are not shown in the drawings for reasons of clarity.

If the actuators 6 use diaphragms rather than pistons 11 operating in cylinders 12, they too can be provided with sensors for detecting movement of the diaphragms to positions which they would not occupy during normal operation and thereby provide analogous signals to the controller to stop the apparatus when this occurs.

The high pressure monitor 19 can be used to guard against excessive pressure in the conduit 16 and 16' and/or excessive tension in the associated cutting tools 2 which might lead to an increased risk of breakage during use. These monitors could be used to operate a pressure relief valve, thereby reducing the pressure in the conduits 16 and 16'. They could additionally and/or alternatively be used to operate an audible and/or a visual warning, or they could be used to stop the apparatus. It is also possible for an appropriate signal to be passed from the controller 20 via the line 24 to slow down the feed of product which is being cut by the apparatus, thereby reducing the risk of a cutting tool being broken as a result of high loadings on the tools when product is fed at high speed to cutting tools which are themselves under high tension.

Although the cylinder or cylinders 12 used for tensioning the cutting tools 2 can be positioned on a replaceable cutter frame, it is generally preferred that they are attached to some other part of the apparatus so that a single set of cylinders can be - 8 used with a variety of frames. This arrangement can serve to reduce the cost of the apparatus, and the frames can then merely use guide pins, groves or the like to enable the distances between adjacent wires or knives to be adjusted, and thereby the distance between cuts and/or the cutting pattern achieved to be altered. The frames can also include markings which enable different positions on the frame to be more readily identified, and thereby facilitate the setting up of different arrangements of cutting tools. The use of variable geometry frames in which.cutting tool lengths and positions can be changed can benefit particularly from the present invention because each change of geometry can be accompanied by slackening and re-tensioning of the cutting tools.

The present invention can enable the replacement of complete frames of cutting tools to be avoided whilst facilitating the in situ removal, replacement and re-tensioning of broken tools with the rest of the tools remaining unaffected.

As will also be appreciated, the present invention can enable the flexibility of use of cutter frames to be increased because repositioning the points of attachment of the ends of the respective cutting tools is simplified compared with hitherto proposed apparatus.

In some instances it may not be desirable or possible to mount the cylinders 6 in line with an associated cutting tool 2. Apparatus in accordance with the present invention can therefore have the various cylinders positioned elsewhere on the apparatus, linkages of one type or another then usually being used to connect the pistons to the associated cutting tools. These linkages can take the form of chains, wires, threads, wire ropes, cords or appropriately hinged rigid rods. It will also be appreciated that the tensioning force exerted by the respective cylinders can be applied in a different direction from the direction of the pistons in the cylinders, for example using levers, bell cranks, pulleys or other suitable guides.

9 Mechanical advantage can also be used by the use of levers, bell cranks or pulleys.

Figures 3a-d illustrate a number of alternative methods of applying tension to individual cutter wires or knives.

Figure 3a shows a wire rope 30 between the piston 11 of the actuator 6 and the cutting tool 2, tension in the rope 30 being applied directly to and in line with the tool 2.

Figure 3b shows the wire rope 30 connected to the piston 11 of an actuator 6 and to a pivotable lever 32 with one end pivotable on the frame or chassis of the apparatus and to the other end of which is attached one end of the cutting tool 2. In the position shown in solid line, the tension in the cutting tool 2 is greater than that applied by the actuator 6, and in the position shown in broken line the tension is less.

Figures 3c and 3d show alternative methods of applying tension to a cutting tool 2 in a different direction from that in which the actuator 6 operates, Figure 3c using a pulley 33 to effect a change in direction of the applied tension, and Figure 3d using a pivotabl'e bell crank 34 which can in addition to changing the direction of the applied tensional force can change its magnitude by changing the relative distances between the points of attachment of the wire rope 30 and the cutting tools 2 and the axis about which the crank 34 rotates.

As will also be appreciated, the ends of the cutting tools 2 can be secured by various means other than the illustrated use of loops in the ends of the tools 2 being located over pins 4. For example, the ends of the tools 2 can be in the form of coils which are slotted into slots in pins or bolts secured to the frame or chassis, tensioning of the tools 2 serving to tighten the coils down on to the associated pin or bolt, thereby holding the tools in position by increased friction. other methods of securing the ends of the tools include the use of toggles or nipples.

- 10 Although it is generally preferred to provide a static mounting point for one end of each cutting tool, it will be appreciated that a tensioning cylinder or diaphragm can be used to apply tension to both ends of a particular tool.

- 11 claims_ 1. Apparatus for cutting soft products, the apparatus comprising:- a) at least one cutting tool for cutting the said product; b) tensioning means for tensioning the said at least one cutting tool, the tensioning means being connected to the said tool and being operable by a compressed fluid; pressuring means for providing a supply of compressed fluid to the tensioning means; and d) pressure monitoring means for monitoring the pressure applied by the pressuring means and thereby the tension applied to the at least one cutting tool by the tensioning means.

2. Apparatus according to claim 1, wherein the compressed fluid comprises air or another gas.

3. Apparatus according to claim 1, wherein the compressed fluid comprises a liquid.

4. Apparatus according to any of the preceding claims, having a plurality of cutting tools.

5. Apparatus according to claim 4, having a single pressuring means for providing compressed fluid for all of the tensioning means associated with the individual cutting tools.

6. Apparatus according to claim 4, wherein one or more of the plurality of cutting tools has separate pressuring means for enabling individual tools to be tensioned independently of the others.

12 7. Apparatus according to any of the preceding claims, including pressure sensing means which senses the tension in the at least one cutting tool created by the pressuring means and stops the feed of product to be cut by the apparatus when the detected pressure exceeds or falls below predetermined maxima and minima.

8. Apparatus acording to any of the preceding claims, wherein the at least one cutting tool comprises a cutter wire, thread, knife or blade.

9. Apparatus according to any of the preceding claims, wherein the tensioning means includes sensor means for detecting unusual movement of the tensioning means in the event that the said at least one cutting tool breaks.

10. Apparatus substantially as herein desc to the accompanying drawings.

ribed with reference