GB2307397A

GB2307397A - Slicing Machine.

Info

Publication number: GB2307397A
Application number: GB9624129A
Authority: GB
Inventors: Philip Edward Furness
Original assignee: Allied Bakeries Ltd; Ibonhart Norwich Ltd
Current assignee: Allied Bakeries Ltd; Ibonhart Norwich Ltd
Priority date: 1995-11-21
Filing date: 1996-11-20
Publication date: 1997-05-28
Anticipated expiration: 2016-11-20
Also published as: GB9523799D0; GB2307397B; GB9624129D0

Abstract

A slicing machine, particularly a bread slicer having a row of blades (3), blade breakages are detected by a mechanism comprising a blade sensor (12) in the form of a diffuse laser mounted on a carriage (10) which is reciprocated back and forth along the row of blades by a double acting fluid cylinder (9). A control device counts the number of blades detected and compares this number with an expected number.

Description

Bread Slicing Machines This invention is concerned with slicing machines and in particular it relates to a slicing machine having several blades arranged in a row, as used for slicing loaves of bread.

The blades generally used in bread slicing machines are not very robust and blade fractures are apt to occur from time to time. As loaves of bread are fed continuously through a slicing machine it is inconvenient if a blade breakage is not detected quickly as it may lead to several loaves being incorrectly sliced and significant spoilage can occur. A blade breakage detection system is known wherein a light beam is directed across the machine, i.e. along the row of blades, from one side of the machine and is detected by a sensor at the other side.

The light beam is projected adjacent blade retaining hooks which cooperate with blade tensioning springs used to secure the blades in frames by means of which the blades are reciprocated in operation of the slicing machine. Movement of a blade retaining hook produced upon fracture of a blade coupled thereto interrupts the light beam, but this does not always occur in a reliable manner e.g. due to the blade hooks becoming seized or jammed in the blade mounting frame. When the beam is interrupted, it is detected by the sensor and the associated control equipment responds by immediately shutting down the machine. Sometimes an interruption of the light beam can be caused other than by a blade fracture and the only way to determine whether all the blades are present and in tact is by visual inspection.

The aim of the present invention, therefore, is to provide a more reliable system for detecting blade breakages in a bread slicing machine. According to one aspect of the invention there is provided a slicing machine having a transverse row of spaced apart blades, a carriage guided for reciprocal movement along the row of blades transversely of the machine, means on the carriage for detecting individual blades as the carriage moves along the row of blades, and control means for determining the number of blades detected.

In accordance with another aspect the invention provides a method of monitoring the condition of a slicing machine having a row of blades, comprising sensing individual blades, counting the number of blades sensed and comparing the counted number of blades with an expected number.

Also in accordance with the invention there is provided a blade detection device for a slicing machine having a row of blades, comprising a carriage mounting a blade sensing means, guide means supporting the carriage for movement substantially parallel to the row of blades, and control means coupled to the sensing means for determining the number of blades detected during displacement of the carriage.

Although other forms of blade detector could be used, in a preferred embodiment the detecting means comprises a means for emitting a beam of electromagnetic radiation and means for sensing radiation reflected from the blades. Most preferably a diffuse laser sensor is provided for detecting individual blades as it can ensure accurate blade detection without need to be positioned in immediate proximity to the blades.

Different mechanisms are possible for mounting the carriage and driving it back and forth along the row of blades. According to a convenient construction, the carriage is supported and driven by a double acting fluid cylinder.

The control means counts the number of blades detected as the carriage transverses the complete row of blades and preferably compares the number counted with the expected number which may be input into the control means. If the number counted does not tally with the expected number, the control means may respond by switching off the machine. It is not essential for this to occur immediately, however, and the control means can be programmed to check by performing a further count of the number of blades before producing any warning signal or shutting down the machine.

A full understanding of the invention will be gained from the following detailed description of a preferred embodiment, reference being made to the accompanying drawings in which: Figure 1 is a side view illustrating blade detecting mechanism according to the invention operatively assembled in a bread slicing machine Figure 2 is an end view of the assembly of Figure 1, as seen in a direction perpendicular to the machine blades; and Figure 3 is a side view illustrating a modified mounting position for the blade detection mechanism.

The bread slicing machine is for the most part of known construction and does not form part of the invention described herein.

Therefore, only those parts of the machine closely associated with the blade detection equipment have been shown in the drawing and will be described. The machine has a frame with upwardly extending side frame members 1,2 which are inclined to the vertical. Similarly inclined and supported by the frame are two knife frames each mounting a series of blades so that a row of blades 3 with substantially uniform spacing extends across the machine. The knife frames are reciprocated substantially parallel to the length of the blades and in opposition to each other for minimizing vibration. A conveyor (not shown) delivers loaves 4 of bread continuously and in succession onto an inclined comb plate 5 and to the blades for the loaves to be sliced in turn by passing through the row of blades.The comb plate 5 provides support for the loaves as they approach and are sliced by the blades and after having been sliced the loaves pass onto a conveyor 6 which carries the loaves away from the slicer for wrapping.

The blade detection equipment is mounted beneath the comb plate 5. A transverse support beam 8 has its ends fastened to the side frame members 1 and 2 and carries a double acting fluid cylinder 9 of the rodless piston type. The piston is attached to a carriage 10 in the form of an aluminium block guided for linear movement along the cylinder in response to reciprocation of the piston. Mounted on the carriage 10 by a bracket 11 is a sensor unit 12 housing a diffuse laser sensor. An elongate chain support plate 13 is supported by a pair of brackets 14 to extend alongside the cylinder 9 over approximately half its length, and a plastic link chain 16 has one end attached to the support plate 13 and its other end attached to a bracket 15 fastened to the carriage 10.The chain is bent through 1800 between its ends and defines a curved path for guiding electric cables (not shown) connected between the sensor unit 12 and a remotely located programmable control device.

Compressed air is delivered alternately to the opposite ends of the cylinder 9, e.g. under control of solenoid valves controlled by the programmable control device, for reciprocating the carriage 10 and hence the sensor unit 12 back and forth across the row of blades 3.

The diffuse laser sensor emits a light beam in the direction towards the blade and includes a sensing device to detect the light beam when reflected from the rear edge of an individual blade. When a blade is detected the sensor unit emits a signal to the programmable control device which is programmed to count the total number of blades detected as the carriage performs a full stroke of movement along the complete row of blades. The number of blades detected is compared with the number of blades with which the machine is equipped, this number being programmed into the control device. If the number counted does not agree with the number of blades expected, the control device can either initiate a warning signal and/or stop operation of the slicing machine. So as to minimise the occurrence of false alarms, the programmable control unit is preferably programmed to complete a further count of the number of blades before stopping the slicing machine.

The number of blades is counted during each back and forth stroke of the sensor unit. Sensors may be mounted to determine when the carriage reaches the ends of its stroke in each direction for the programmable control unit to actuate the solenoid valves so that the carriage movement will be reversed. Thus, the row of blades can be scanned continuously and any blade breakage will be detected promptly, but also with greater certainty than with prior art systems.

To prevent the slicing machine being started when one or more blades are missing, the programmable control unit may be programmed so that a blade count is performed and a machine operator has verified that the correct number of blades are present. For this purpose the control unit may cause the number of blades counted to be shown on a visual display and await confirmation that it is correct e.g. by the operator pressing a button on an interface panel.

Figure 3 illustrates a modified assembly in which the blade detection mechanism is mounted on the bread slicer frame by brackets 20 above the path of the loaves. The blade detecting mechanism is otherwise constructed and controlled as described above in relation to Figures 1 and 2, the same reference numerals having been used to denote corresponding parts in the drawings. Positioning the blade detection equipment as shown in Figure 3 can avoid any risk of falling crumbs giving rise to a blade miscount.

Although the invention has been described and illustrated applied to a slicer with inclined blades, it is equally applicable to slicers with vertical blades. Other modifications are also possible without departing from the scope of the invention. Measures can be taken to reduce the risk of incorrect blade counts due to crumbs dislodged from the loaves of bread during slicing. Such measures might include the use of shrouds to surround or partially surround the path of the blade detection beam between the sensor and the blades, and/or the use of air jets to deflect crumbs away from the beam path.

In another arrangement the embodiment illustrated in Figure 1 is modified to include a fibre optic bundle extending from a sensor box housing a light source and light sensor, to a fibre optic head carried by a positioning device, such as a fluid cylinder, operable to position the fibre optic head closely adjacent the blades, e.g. at a few millimetres from the blades. The fluid cylinder, which can be used to retract the fibre optic head, such as to facilitate blade replacement operations, can be mounted on the carriage bracket 11 in the position shown occupied by the sensor unit 12, and the alternative sensor box can be mounted on the bracket behind the carriage 10. Some of the fibres in the fibre bundle serve to transmit light from the light source and others transmit back to the light sensor emitted light reflected from the blades.

It will be appreciated that any type of sensor capable of detecting individual blades could be used with the described apparatus without departing from the inventive concept, one example of an alternative type of sensor being an inductive sensor.

Claims

1. A slicing machine comprising a row of spaced apart blades, a carriage guided for reciprocal movement along the row of blades, means on the carriage for detecting individual blades as the carriage moves along the row of blades, and control means for determining the number of blades detected.

2. A machine according to claim 1, wherein the blade detecting means includes means for emitting a beam of electromagnetic radiation and means for sensing radiation reflected from a blade.

3. A machine according to claim 2, wherein the beam emitting means comprises a light source.

4. A machine according to claim 3, wherein the light source is a laser.

5. A machine according to any one of claims 1 to 4, wherein a fluid cylinder is coupled to the carriage for moving the carriage along the row of blades.

6. A machine according to claim 5, wherein the carriage is supported and driven by a double acting fluid cylinder.

7. A machine according to any one claims 1 to 6, wherein the control means is arranged to compare the number of blades counted with an expected number and to emit a signal if the counted number is not equal to the expected number.

8. A method of monitoring the condition of a slicing machine having a row of blades, comprising sensing individual blades, counting the number of blades sensed and comparing the counted number of blades with an expected number.

9. A method according to claim 8, wherein the blades are sensed by a common sensing means displaced along the row of blades.

10. A method according to claim 9, wherein a signal is emitted to stop the machine and/or to generate a warning signal if the counted number is not equal to the expected number.

11. A method according to claim 10, wherein the signal emission is delayed for the number of blades to be sensed and recounted to verify that the counted number is correct.

12. A blade detection device for a slicing machine having a row of blades, comprising a carriage mounting a blade sensing means, guide means supporting the carriage for movement substantially parallel to the row of blades, and control means coupled to the sensing means for determining the number of blades detected during displacement of the carriage.

13. A device according to claim 12, wherein the sensing means comprises means for emitting a beam of electromagnetic radiation and means for sensing radiation reflected from a blade.

14. A device according to claim 13, wherein the beam emitting means comprises a light source.

15. A device according to claim 14, wherein the light source is a laser.

16. A device according to any one of claims 12 to 15, wherein a fluid cylinder is coupled to the carriage for moving the carriage along the row of blades.

17. A device according to claim 16, wherein the carriage is supported and driven by a double acting fluid cylinder.

18. A device according to anyone of claims 1 to 7, wherein the control means is arranged to compare the number of blades counted with an expected number and to emit a signal if the counted number is not equal to the expected number.

19. A blade detection device in or for a slicing machine, substantially as herein described with reference to the accompanying drawings.

20. A method of monitoring the blades of a slicing machine substantially as herein described.