GB2099609A

GB2099609A - Slicing machine

Info

Publication number: GB2099609A
Application number: GB8215756A
Authority: GB
Original assignee: Thurne Engineering Co Ltd
Current assignee: Thurne Engineering Co Ltd
Priority date: 1981-06-02
Filing date: 1982-05-28
Publication date: 1982-12-08
Also published as: GB2099609B

Abstract

A slicing machine for slicing meat and meat products includes means (10) to weight the piece of meat or meat product and output a weight signal representing the weight of the piece of meat or meat product, and means (12) responsive to the length of a piece of meat or meat product to provide a length signal representative of the length of the piece of meat or meat product. The slicing machine also includes means (14) to divide the length signal by the weight signal to provide a signal representative of the average length per unit weight of the piece of meat or meat product, a reference signal generator (13) to produce a reference signal indicative of the required weight of each slice, and means (14) to calculate the feed rate by multiplying the signal representing the average length per unit weight by the reference signal. The output of the means (14) is then supplied to means (5) to set the feed rate of the meat or meat product towards the blade (2) of the slicing machine so that the thickness and hence the weight of the slices cut by the slicing machine are controlled in accordance with the average length per unit weight of the piece of meat or meat product. <IMAGE>

Description

SPECIFICATION Slicing machine This invention relates to slicing machines for slicing pieces of meat and particularly the slicing of pressed or moulded meat products.

Slicing machines for slicing meat and other meat products comprise a rotating blade which either has a spiral cutting edge or has a circular cutting edge and is mounted for planetary motion, and means to feed the side or piece of meat or meat product towards the blade so that, upon each revolution or each gryration of the blade one slice is cut from the face of the piece of meat or block of meat product. The means to feed the piece of meat or other meat product may be a continuous conveyor but usually the slicer includes a fixed platform on which the piece of meat or block of meat product is placed and a gripper unit which engages the rear face of the piece of meat or block of meat product and which urges the piece of meat or block of meat product towards the blade.The gripper unit may be moved by a hydraulic ram or by a leadscrew driven by a stepping or variable speed electric motor. Conventionally, the meat or meat product is moved forward at a constant speed so that each successive slice has a substantially constant and uniform thickness.

It is also known, particularly in the case of a slicing machine with a plurality of blade, for the piece of meat or meat product to be moved forward stepwise each time the blade is away from the piece of meat or meat product. Again the size of each step is constant so that the thickness of each slice is substantially constant and uniform. In practice conventional slicing machines include a thickness selector unit the operation of which controls the slice thickness by throttling the flow of hydraulic liquid downstream of the ram or by varying the speed of or stepping control of the motor driving the leadscrew.

Such slicing machine are usually used as the first stage of a packaging line and it is naturally desirable to be able to slice the meat or other meat product into slices having a particularly preferred weight so that a whole numbest of slices makes up a package of the required weight. In the past, when the meat or meat product is moved towards the blade at a constant speed, the slicer has been arranged so that a particular required number of slices give under the required weight and then a portion of a single slice is added to the package, often by hand, to make the package up to the required weight.

More recently, slicing machines have been made more sophisticated by the inclusion downstream from the slicing machine of means to weight a group of slices cut by the slicing machine, and then, in dependence upon the weight of that single group, vary the speed of movement of the feed of meat or meat product by a feedback system to ensure, as far as possible, that each slice has a particular, predetermined weight. This apparatus is very complicated and inevitably there is some time lag between the cutting of a group and the determination that that group has been cut too thick or too thin, and then a further time lag before the feed speed of the meat or meat product is changed to correct this. It has been found that when the slice thickness is adjusted in this way independence upon the weight of a preceding group, it does not always produce the desired effect and errors often increase.Therefore, in spite of its sophistication, this most recent technique does not provide a satisfactory solution and enable slices of constant and uniform weight to be cut by the slicing machine.

According to this invention a slicing machine for slicing meat and meat products includes means to weigh the piece of meat or meat product and output a weight signal representing the weight of the piece of meat or meat product, means responsive to the length of a piece of meat or meat product to provide a length signal representative of the length of the piece of meat or meat product, means to divide the length signal by the weight signal to provide a signal representative of the average length per unit weight of the piece of meat or meat product, a reference signal generator to produce a reference signal indicative of the required weight of each slice, means to calculate the feed rate by multiplying the signal representing the average length per unit weight by the reference signal, and means responsive to the output of the means to calculate to set the feed rate of the meat or meat product towards the blade of the slicing machine.

We have found that it is possible to obtain packages of substantially the correct weight by simply selcting the thickness of the individual slices in the package in dependence upon the average length per unit weight of the piece of meat or meat product. Since joints of meat are a natural product, they are not uniform throughout their length. Their cross-sectional area may vary throughout their length, but sides of bacon and similar natural meat products are often pressed before slicing to improve their cross-sectional uniformity along their length. Moulded or pressed meat products also have a reasonably uniform cross-section along their length. However, since all meat and meat products are a natural product their density is not uniform, for example as a.

result of the meat to fat ratio varying along the length of each piece of meat or meat product and also varying from one piece to the next. We have found that providing the thickness of the slice is based upon the average length per unit weight the weight of a package of the resulting slices is surprisingly accurate and surprisingly close to the required weight. We have certainly found that the results achieved with this system are better than those which can be achieved using a feedback system where the feed rate of the piece of meat to the slicer is varied in dependence upon the weight of one of the previously cut slices.It is believed that the weight of individual slices still varies from one slice to the next, possibly as a result of changes in the meat to fat ratio, but these variations tend to be averaged out amongst a group of successive slices to that the weight of a package of slices is substantially equal to the required weight. In this way the present invention takes account of differences in the cross-sectional area of different pieces of meat and blocks of meat product and adjusts the thickness of the slices of that piece of meat or block of meat product accordingly.

Preferably the construction of the remainder of the slicing machine is entirely conventional except that the slice thickness selector unit is replaced by the means to calculate and the means responsive to the output of the means to calculate. Thus the means responsive to the output of the means to calculate controls the throttling of the flow hydraulic liquid downstream of the ram or controls the speed or stepping control of the motor driving the leadscrew.

Preferably the slicing machine includes selector means to select a particular predetermined reference signal from a series of different predetermined reference signals. This enables the slicing machine to aim for, for example, seven slices per half pound when slicing back bacon and eleven slices per half pound when slicing streaky bacon. The selector means preferably includes a series of push button switches or a selector switch with a dial and preferably these carry indicia indicating the nature of the meat or mea product to be sliced. Thus the selector switch preferably includes indicia reading, for example, "back bacon", "streaky bacon", "ham", "sausage", and so on. This facilitates the use of the machine by substantially unskilled operators.

Preferably the means to weigh the piece of meat and produce an electrical signal includes a platten upon which the meat is placed which bears on a load cell having an output in the form of an analogue electrical signal. The platten preferably also includes an abutment and has associated with it the means responsive to the length of the piece of meat or meat product. This maybe formed by a caliper arm which is movable along the platten and which is coupled to a potentiometer.In this way a piece of meat or block of meat product is placed on the platten with one end against the abutment and then the caliper arm is moved along the platten until it engages the other end of the piece of meat or block of meat product At this point the resistance of the potentiometer has a particular value which is indicative of the length of the piece of meat or meat product. Convenientfy the potentiometer is set up as a potential divider so that its output is in the form of an analogue voltage signal the voltage of which varies with the length of the piece of meat or block of meat product.

Alternativeiy the means responsive to the length of the piece of meat or block of meat product includes an ultrasonic distance measuring device. In this case, the ultrasonic distance measuring device is set up adjacent the end of the platten remote from the fixed abutment. The piece of meat or block of meat product is placed on the platten with one end aganst the fixed abutment and the ultrasonic distance measuring device measures the distance between itself and the other end of the piece of meat or block of meat product The ultrasonic distance measuring device may also subtract this distance from the known distance between the fixed abutment and the device to produce the length signal indicative of the length of the piece of meat or block of meat product Alternatively the means to divide the length signal by the weight signal may also subtract the output of the ultrasonic distance measuring device from the known distance between the fixed abutment and the device to produce the length signal.

The means responsive to the length of the piece of meat or block of meat product may instead include an elongate array of photoelectric devices arranged along the platten.

Preferably the means to divide the length signal by the weight signal and the means to multiply the average length per unit weight signal with the reference signal are formed by a programmed computer. It is especially preferred that the programmed computer is an eight bit microprocessor together with associated interface units to handle the signals from the means to weigh the piece of meat or block of meat product and from the means responsive to the length of the piece of meat or block of meat product.

The rotational speed of a blade with a spiral cutting edge or the orbital speed of a planetary blade may be constant. However when this speed is variable the slicing machine preferably also includes means to generate a signal representative of the slicing speed and this signal is fed to the means to calculate the feed rate where it is multiplied by the reference signal and the length per unit weight signal to provide the feed rate signal.

Two examples of a meat slicer in accordance with this invention will now be described with reference to the accompanying drawings; in which: Figure 1 is a block diagram of a first example; and, Figure 2 is a block diagram of a second example.

The first example of slicing machine in accordance with this invention is a modified Anco slicer made by the Anco Corporation of the United States of America. These slicers are well known and are the standard slicer in use in this country today for the slicing of bacon. The slicer comprises a horizontal bed 1 and a rotating blade 2 having a spiral cutting edge. The blade rotates about a horizontal axis extending along and above the bed 1 and rotates at a constant angular velocity. The side of bacon or other meat product to be sliced is placed on the horizontal bed 1 and its face remote from the blade 2 is engaged by a gripper 3. The gripper is driven by a hydraulic ram 4 to urge the side of bacon or block of meat product towards the blade 2. The thickness of the slices that are cut by the blade 2 thus depends upon the feed rate of the gripper 3.The feed rate of the gripper 3 is determined by a variable orifice throttle valve 5 connecting to the outlet from the ram 4 which has a constant pressure hydraulic input 6. These features are all standard on any Anco slicer.

To modify such a slicer in accordance with this invention a platten 8 including an abutment 9 at one end is mounted on a load cell 10. The platten 8 has a caliper arm 11 mounted on it so that the caliper arm 11 can slide along the platten 8. The caliper arm 11 is coupled to a multi-turn potentiometer 12 through rack and pinion gearing (not shown). A control box 13 includes a series of push button switches which actuate reference signal generators providing reference signals indicative of the required weight of each slice.

Electrical signals from the load cell 10, the multi-turn potentiometer 12 and the control box 13 are fed to a programmed computer 14 which typically comprises an eight bit digital microprocessor with associated input and output interface circuits such as analogue to digital converters and digital to analogue converters. An analogue control voltage is output from the computer 14 to the variable orifice throttle valve 5 and, in use, adjusts the flow of hydraulic fluid through the throttle valve 5.

In use an operator places a piece of meat or block of meat product on the platten 8 with one end against the abutment 9. The operator then manually moves the caliper arm 11 so that it abuts the other end of the piece of meat or block of meat product. The operator then pushes one of the push buttons on the control box 13.

Preferably these push buttons are labelled with descriptions of the products to be sliced. A signal representing the weight of the block of meat is fed from the load cell 10 to the computer 14. The multi-turn potentiometer 1 2 is connected as a potential divider and so also transmits an electrical signal to the computer 14 which varies in dependence upon the length of the block of meat or meat product and the control box 1 3 after actuation of one of the push buttons feeds a reference signal to the computer 1 4 which indicates the desired weight of each slice.

Naturally these analogue signals are all converted to digital form in the interface circuits of the microprocessor then the digital microprocessor computes a feed rate signal by dividing the length signal output by the potentiometer 12 by the weight signal output by the load cell 10 to provide an average length per unit weight signal. The microprocessor then multiplies this signal by the desired slice weight signal from the control unit 1 3 and a constant multiplier representing the slicing speed, that is the rotational speed of the blade 2 to provide a feed speed signal.This feed speed signal is converted to an analogue control voltage by the digital to analogue converter in the interface circuit of the microprocessor and then applied to the variable orifice throttle valve 5 to govern the rate of movement of the gripper 3 and hence the rate of movement of the block along the horizontal bed 1 of the slicing machine and in turn the thickness and hence the weight of each slice that is cut by the blade 2 from the piece of meat or block of meat product.

The second example of slicing machine in accordance with this invention is based upon the Polyslicer (registered trade mark) slicing machine manufactured and distributed by Thurn Engineering Limited of Great Britain. This slicing machine includes an inclined bed 1 5 and a rotating orbiting blade 16.A gripper 17 slides along the inclined bed 1 5 and is driven along the inclined bed 15 by a leadscrew 1 8 which is rotated by a variable speed electric motor 1 9. In practice the blade 1 6 orbits at a constant angular velocity and the thickness of the slices cut by this slicer are determined by the rate at which the block of meat is fed by the gripper 1 7 which is, in turn, controlled by the rotation of the leadscrew 1 8 by the electric motor 1 9.

To modify this standard slicing machine in accordance with this invention a generally similar system is used to that described with reference to the first example and, where appropriate similar reference numbers are used. This example also includes a platten 8 having a fixed abutment 9 mounted on a load cell 10, a control unit 13, and a programmed computer 14. This example includes an ultrasonic distance detector 20, for example an ultrasonic distance detector manufactured by Sonic Tape Limited of Great Britain, and a motor controller 21.

Again the block of meat product to be sliced is placed on the platten 8 with one end against the abutment 9. The ultrasonic distance detector 20 transmits pulses of ultrasonic sound which are reflected from the other end of the block of meat product and returned to the ultrasonic distance detector 20. The ultrasonic distance detector 20 thus measures the distance between itself and the other end of the block of meat product.

However, the distance detector 20 includes internal circuitry which enables this measured distance to be subtracted from a pre-set distance which is, set up to correspond to the distance between the distance detector 20 and the abutment 9. Thus, the output from the distance detector 20 is a signal indicative of the length of the block of meat product. Once again the load cell 10 gives a signal representing the weight of the block of meat and the control unit 13 provides a reference signal corresponding to the required weight per slice. These signals are again computed in exactly the same way in the programmed computer 14 to provide an analogue control voltage which is applied to the motor controller 21 which in turn controls the speed of rotation of the electric motor 1 9 and, the rotation of the leadscrew 1 8 and hence the forward movement of the gripper 17 and the block of meat product when it is being sliced.

Claims

1. A slicing machine for slicing meat and meat products including means to weigh the piece of meat or meat product and output a weight signal representing the weight of the piece of meat or meat product, means responsive to the length of a piece of meat or meat product to provide a length signal representive of the length of the piece of meat or meat product, means to provide the length signal by the weight signal to provide a signal representative of the average length per unit weight of the piece of meat or meat product, a reference signal generator produce a reference signal indicative of the required weight of each slice, means to calculate the feed rate by multiplying the signal representing the average length per unit weight by the reference signal, and means responsive to the output of the means to calculate to set the feed rate of the meat or meat product towards the blade of the slicing machine.

2. A slicing machine according to claim 1, including selector means to select a particular predetermined reference signal from a series of different predetermined reference signals, to enable the slicing machine to aim for, for example, different numbers of slices per pack when slicing different products.

3. A slicing machine according to claim 1 or 2, in which the means to weigh the piece of meat and produce an electrical signal includes a platten upon which the meat is placed which bears on a load cell having an output in the form of an analogue electrical signal.

4. A slicing machine according to claim 3, in which the platten-includes an abutment and has associated with it the means responsive to the length of the piece of meat.

5. A slicing machine according to claim 4, in which the means responsive to the length of the piece of meat or meat product is formed by a caliper arm which is movable along the platten and which is coupled to a potentiometer.

6. A slicing machine according to claim 4, in which the means responsive to the length of the piece of meat or block of meat product includes an ultrasonic distance measuring device.

7. A slicing machine according to any one of the preceding claims, in which the means to divide the length signal by the weight signal and the means to multiply the average length per unit weight signal with the reference signal are formed by a programmed computer.

8. A slicing machine according to any one of the preceding claims, in which the slicing speed is variable, in which the slicing machine also includes means to generate a signal representative of the slicing speed and feed it to the means to calculate the feed rate, the means to calculate the feed rate multiplying the signal representative of the slicing speed by the reference signal and the length per unit weight signal to provide the feed rate signal.

9. A slicing machine according to claim 1, constructed substantially as described with reference to the accompanying drawings.