AU2022209233A1

AU2022209233A1 - Safety apparatus for a power operated skinning machine with a fixed blade.

Info

Publication number: AU2022209233A1
Application number: AU2022209233A
Authority: AU
Inventors: Keith Blenkinsopp; Shaun HURD; George Maddever; Winston Duang Wickham
Original assignee: Kando Innovation Ltd
Current assignee: Kando Innovation Ltd
Priority date: 2019-11-06
Filing date: 2022-07-26
Publication date: 2022-08-18
Also published as: AU2020264309B2; AU2020264309A1

Abstract

A skinner or derinder is provided with an imaging optical sensing system to detect an operator's hand close to, or in dangerous proximity to the skinner blade and to make a motor driving a gripping roller to stop before the hand makes contact with the blade. Video cameras, disposed at distant ends of two tunnels mounted on the chassis and terminating with clear windows near the ends of the blade, form images of an elongated volume adjacent the blade. For example, a blue or green glove may be detected.

Description

SAFETY APPARATUS FOR A POWER OPERATED SKINNING MACHINE WITH A FIXED BLADE.

FIELD A shaping or cutting machine at which an operator hand-feeds material to be cut or shaped toward a blade for which the machine is made safe by adding hand sensing and blade retraction. The present invention describes operator safety modifications for a skinning or .0 derinding machine for meat, poultry or fish having an elongated skinning blade mounted along and just above a gripping roller.

DEFINITIONS

De-rinder is a name for a form of skinning machine. In this document, the word "skinner" also refers to a "derinder".

.5 Unsafe Proximity is a term describing a location of a worker's hand or glove that is dangerously close to, or in imminent contact with a blade. In this document the term is synonymous with, or a subset of a "surveilled volume".

Run Position describes the skinning machine when in use, in a working mode.

BACKGROUND

Shaping or cutting machines at which an operator hand-feeds material to be cut or shaped toward a blade are widespread, for example in the meat or food industry and for shaping wood. Power operated skinning equipment is widely used in parts of the food industry, to cut a layer from a workpiece of flesh to be skinned or de-rinded. See for instance "Marel", "Townsend" or "Graselli" brand skinners for meat, fish, poultry and pork. Some skinners handle whole pork carcasses, others accept hand-held items, and yet others have a conveyor feed. It is often required that an operator places his or her hands on an object to be skinned, presenting the object, with the aid of a moving platform underneath the object, towards a sharp knife blade. Since an operator's hands are not greatly different in consistency to the material to be skinned, preventing the operator's hands from injury is difficult. The moving platform is typically a powered gripping roller having a maintained surface velocity.

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Prior art skinners that sense and respond to the presence of a hand in a dangerous place have relied on contact sensing and bringing the gripping roller to a halt only after contact is sensed. It has been conventional to rely on a woven metal mesh as a protective layer inside the operator's conductive gloves. Roller stopping times appear to be unable to prevent some damage to the hand. Also, the material being cut is non-rigid and inertia may continue to carry it toward the blade even if the moving platform stops.

PROBLEM TO BE SOLVED

.0 This document describes safety modifications for machines known as skinners or de-rinders, in which an operator physically holds the item to be cleaved by a sharp blade and advances the item toward the blade, aided by a rotating gripping roller. The prior art relies on glove contact sensing, in which metal mesh gloves complete a circuit that signals a hazardous state. Conductive sensors of proximity do not give sufficiently early warning to an activation .5 apparatus because the blade is already in contact. The gripping roller may have engaged with the worker's hand or hands, or may have caught a glove. The worker may slip, or be fatigued.

A preferred operator protection device would create a warning of dangerous proximity and convert it into a useful action by bringing the gripping roller to a rapid halt so that the operator's gloved hand does not touch the blade.

o PRIOR ART REVIEW KR 102096621 to Donwoo Co Ltd ( Jung Jin Sook, 2 April 2020) describes a skinner in which a hand detection unit or "tentacle sensing unit 800" is disposed in order to detect a close approach of a hand of a worker toward the blade roller 210. It is the only known optical system for skinners. The text includes "800 has a light emitting unit and a light receiving unit disposed to face each other on the upper part of the blade roller 210" It is a "multiple beam interruption" device, triggered by any interruption of the beams but is not an image sensor responsive to reflected colour. A control unit 700 for the gripping roller motor is configured to stop the roller from rotating when the hand of the worker is determined to have approached the blade roller.

US 5272946 McCullough (28 December, 1993) describes a skinner in which a hand touch detection and response unit comprises a motor, a clutch and electrical connections to each of a left-hand and a right-hand conductive glove including a metal mesh. A mechanism provides

2 KANDOI9_32 that the roller becomes disengaged from the motor and is caused to reverse momentarily in order to prevent trapping of an operator's finger or glove end between the roller and the knife blade. The mechanism is triggered by contact between either glove and a component of the skinning machine, including the tooth feed roller, the knife blade, or other parts.

EP 0 362 947 to Grasselli and McCullough (priority 4 October, 1988) describes a skinner. Care is taken to maintain electrical connection with the worker and the conductive gloves that the worker wears. The document highlights the problem of relying on an open circuit to '0 indicate normal or safe function. Because a closed circuit indicates danger, a circuit that is already disconnected elsewhere is unsafe.

SUMMARY OF THE INVENTION.

In a first broad aspect, the invention provides a skinner machine for which an item of flesh to be shaped is held by an operator's hand or hands; the machine having a chassis and having a blade supported on a blade mount located above and parallel to a rotatable gripping roller driven by a motor, the item being advanced, when in use, at a feed velocity and in a direction toward a front edge of the blade by the gripping roller, wherein the machine includes an imaging proximity sensing apparatus adapted to detect the operator's hand or hands and if, when in use, an image of said hand is detected as being inside a dangerous volume previously determined to be located in dangerous proximity to the blade, the proximity sensing apparatus makes and transmits a SIGNAL that is connected in order to cause a motor control apparatus to stop the motor, thereby halting the gripping roller and rendering the machine safe.

Preferably the imaging proximity sensing apparatus incorporates at least one video camera with a lens that is disposed to view a surveilled volume located parallel to an axis of the gripping roller, along and above the gripping roller and in front of the elongated blade; the surveilled volume surrounding and including the dangerous volume.

Preferably the operator's hand is covered by a glove having a contrasting optical signature if visible against a remainder of the image; said optical signature comprising a colour contrast or a brightness contrast or a combination.

In one option a colour contrast is promoted if the operator wears gloves having a contrasting colour against flesh that is selected from a range including green or blue or fluorescent yellow for use in the meat industry.

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In a subsidiary aspect, the imaging proximity sensing apparatus employs a plurality of video cameras all of which receive views along the surveilled volume and the proximity sensing device is configured to generate the SIGNAL if at least one camera output carries information that a portion of the operator's hand is seen in unsafe proximity to the blade.

In one option, the imaging proximity sensing apparatus is also responsive to conduction of electricity from any conductive part of the machine, including the blade, through conductive gloves and will generate the SIGNAL in event of conduction being detected.

In an optional aspect, the imaging proximity sensing apparatus is adapted to provide a warning if the operator's hand is detected inside the surveilled volume yet is outside the dangerous volume.

Preferably the machine is provided with two cameras concealed on each side of the machine; the fields of view of all the cameras being directed along the surveilled volume through windows adjacent both ends of the gripping roller.

Preferably the machine includes an optical assembly behind each window; each optical assembly comprising a sealed tunnel having a length and at least one transparent window thereby permitting use of a longer focal length imaging lens for each camera; said lens having an effect, when in use, of extending a depth of focus within the surveilled volume and the .0 dangerous volume.

Optionally the tunnel is folded, by including a deflecting mirror near each window.

Preferably, the motor of the gripping roller comprises a controllable motor capable of bringing the roller to a halt within 10-15 milliseconds after a motor controller connected to the motor receives the SIGNAL.

Optionally, the motor of the gripping roller comprises a self-braking induction motor capable of bringing the roller to a halt within 100 milliseconds after interruption of power to the motor in response to the SIGNAL.

OBJECT

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A first object of the invention is to provide a safe working environment for an operator of a .0 skinner machine by detecting a glove that is too close to the knife blade, and stopping the roller, while a further object is to at least to provide the public with an alternative choice.

PREFERRED EMBODIMENT

The descriptions of the invention to be provided herein are given by way of example and are not to be taken as in any way limiting the scope or extent of the invention. Throughout this .5 specification, the word "comprise" and variations such as "comprises" or "comprising" should be understood to imply the inclusion of a stated option, integer or step, but not the exclusion of any other option, integer or step. Each document, reference, patent application or patent cited in this text is expressly incorporated herein in its entirety, by way of reference. But reference to cited material or to information in the text, should not be understood as a concession that the material or information was part of the Common General Knowledge or was known in New Zealand or in any other country.

LIST OF DRAWINGS

Fig 1 is an oblique view of the entire skinner machine, with one side cover removed, showing one sealed tunnel serving as an optical path.

.5 Fig 2 is a cross-section showing the gripping roller, the blade and a viewing window when in the Run Position.

Fig 3 is an oblique view of the machine vision arrangement.

Fig 4 is a cross section at A---A to show the surveilled area in relation to the gripping roller.

Fig 5 shows the relation of the servo motor to the gripping roller.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a modification of a kind of cutting or shaping machine used in meat processing plants and slaughterhouses and known as a "skinner" or "derinder"; hereinafter referred to as a skinner. Related machines are used in other industries such as leather manufacture.

Typical skinners have a chassis and a top surface at a height convenient for a standing worker. The blade is held by a blade mount allowing removal and replacement with a sharp blade when required. A gripping roller powers advance of the work item to the blade at a feed

5 KANDOI9_32 velocity and in a direction toward a front edge of the blade and is rotated by a motor. The construction of a skinner is inherently unsafe since the worker's hand or hands can be severely traumatised by the sharp blade. The gripping roller may have engaged with the worker's hand or hands, or a glove may become entangled, while the rotating gripping roller is still drawing the hand or hands toward the blade. The worker may slip, or be fatigued.

The invention defines a surveilled volume as extending across the machine, parallel to the edge of the blade, above the blade, and extending toward the operator. In an enhancement, a "dangerous volume" is defined inside the surveilled volume so that the machine responds with alacrity and halts the gripping roller only if the hand is inside the "dangerously close position". Otherwise, a warning signal is created. The invention differs from the prior art by using optical detection of an image of at least one part of the operator's hand, when included in an output of any one camera of the two or preferably four cameras. The invention is ,0 responsive to proximity, not contact.

If an image of a hand is detected as being inside the surveilled volume, or, more particularly, inside a volume deemed to be in dangerous proximity to the blade, the imaging proximity sensing apparatus will make and transmit a SIGNAL to cause a motor control apparatus to stop the motor until the proximity sensing apparatus is manually reset, thereby halting the gripping roller and rendering the machine safe.

Fig 1 is an oblique view of a prototype skinner machine 100 according to the invention. A side safety cover is removed for the purpose of the illustration so that part of the structural chassis 105 is visible. An operator position is toward the left, near a set of user controls 104. An exposed horizontal working surface is at a convenient height and incorporates a top portion of a gripping roller 110 bearing friction-inducing ridges, teeth or the like, driven in order to carry an article to be skinned away from the operator against a skinner knife 107 (not shown in Fig 1), situated above and close to the roller. A box 103 containing machine-vision cameras (301,302) and lenses (305,306) is aligned with a right-side view tunnel 108. The machine includes a "bone bin" (not shown) for cut waste material that had passed between the gripping roller and the blade.

Fig 2 shows a cross-section through the gripping roller 110 and including a viewing window 111 above the knife, to show the extent of the surveilled volume and of the portion of that volume close to the knife that is deemed to be the dangerous volume.

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When in use, the operator's hands are covered by gloves having a contrasting optical .0 signature to an signature of a material being cut. The inventors prefer to use a colour that forms a contrast distinct from the flesh item being skinned. For instance a green or a blue glove (widely used in the meat industry) forms a contrast as compared to the colour of meat or fatty materials in a shade ranging from white to red. Alternatively the optical signature could be a brightness contrast such as if the gloves are dyed in a fluorescent colour, and the '5 selected illumination excites fluorescence. The fluorescent colour could be outside the visible range.

The imaging proximity sensing apparatus uses typically two, or more preferably four colour video cameras 301, 302 and (303, 304) as in Fig 3 for detection of images of objects to be protected within the volume to be surveilled. The preferred cameras are a colour machine '0 vision type, having a high frame rate.

The imaging proximity sensing apparatus is configured to generate the SIGNAL if at least one camera output demonstrates that any portion of the operator's hand is in unsafe proximity to the blade, inside the surveilled volume, The apparatus includes a programmable device or signal processing means to process the video stream from each camera in order to generate an '5 alarm SIGNAL, and manages communications, power-on testing, safety testing, and loading the energy storage and release device. The preferred cameras are compatible with digital processing. The video components and signal processing means are based on the imaging proximity sensing apparatus described in the Applicants' PCT application PCT/NZ2017/050044, the contents of which are incorporated by way of reference.

Signal processing comprises detection of a contrasting colour or brightness within a contiguous group of pixels in any image collected by any one or more of the colour cameras, and generating the SIGNAL if enough contiguous pixels are found. Optionally, only a part of the image from each camera is processed, such as by limiting the analysed frame in order to control the height of the volume to be surveilled or treated as dangerous.

Fig 3 is an oblique view of the optical components of the skinner machine as seen by an operator. Fig 4 is an elevation cross-section A---A from Fig 3, including background. A pair of cameras is provided at each side of the skinner machine. Each camera 301 and 302 is drawn at the right of Fig 3, but cameras 303 and 304 and their lenses are not shown, being sealed in a case. Each camera lens (305 and 306 are shown) receives an image from the volume to be surveilled after passage through a sealed tunnel 108 (removed at the right side

7 KANDOI9_32 in Fig 3) including deflection by a 45 degrees mirror inside a casing 310 (R) or 315 (L) after passage from the volume to be surveilled through the transparent window 111 within a plate.

The mirrors allow the tunnels to be bent for compactness. Tunnel length serves to displace the camera lenses from the surveilled volume and reduces a proportional difference in .5 distance between near and far ends of the volume. Note the long taper of the bundles of rays shown as 307 in Fig 3. As a result, all camera views have a reasonable depth of field so that an object at any position along the length of the blade is in reasonable focus, and the image is provided at a higher sharpness for discrimination. The combined surveilled volume is along the blade and in a sector parallel to and immediately above the gripping roller 110 and .0 extends from above the roller axis to about 50 degrees toward the inward side, at the left of Fig 4; refer to Fig 2 for a closer view. The height of the surveilled volume 816 may be about 10-35 mm (under software control) so that operator hands, if on a course leading to contact with the knife, start a response, but not if they are safely above the danger area. Measurements may be varied by design.

.5 Optionally the imaging proximity sensing apparatus is adapted by creating two zones, to provide a graded warning. If the operator's hand is near, or just inside the surveilled volume the proximity sensing device may issue a warning such as an acoustic signal. The operator learns not to extend a hand further into the second zone, the smaller dangerous volume, but if that happens, the SIGNAL is produced and the skinner is stopped.

The volume to be surveilled is lit by an included high-intensity strip light source; for example one sealed inside a trough 515. Relatively intense light allows each camera lens to be operated with a smaller aperture for a longer depth of field yet retain adequate image brightness.

Please refer to Fig 5. The currently preferred option for gripping roller rotation is to use a specialised motor 501 which is a servo-motor having a matched controller. The selected motor is used to positively drive the gripping roller 110 at an optimum speed selected in accordance with the material being processed. The Ethernet-compatible motor controller can actively bring rotation to a halt in 10-15 milliseconds of receiving the SIGNAL from the imaging proximity sensing apparatus. A preferred motor 501 is an AM8052-3F10 servomotor having a power rating of 1.6 kW. (Manufacturer: Beckhoff, Germany. Beckhoff also supplies controllers). The motor is contained within the chassis of the skinner and is coupled to the roller through a toothed rubber belt 502 and belt tensioning pulleys. The motor drives the

8 KANDOI9_32 shaft of the cleaning roller 112, which in turn drives the gripping roller shaft through another timing belt 113 (obscured). The cleaning roller is conventional. Low-inertia rollers are .5 preferred. Possibly, the belt drives described in this document may have to be replaced by a train of gears if the force involved in stopping the drum is too great. In a derinder, the cleaning roller is not included and belt drive arrangements will be altered accordingly - or the cleaning roller could be replaced by a transverse shaft. Fig 5 would place the operator toward lower right and includes an elongated well 515 for a strip light; also one of the mirrors 31a (here shown removed from its housing) and a window 511 used for detection of an operator's hand or hands with machine vision.

The motor of the gripping roller for some applications may be a self-braking induction motor having a single or three-phase connection and a selected power rating. It could bring the roller to a halt within about 100 milliseconds after interruption of power by an interruptor that responds to the SIGNAL. Brands of self-braking motor include Motive.srl and Neri Motori in Italy, and Bodine in the United States. The inventors would prefer to include a rotation sensing transducer on the motor shaft and devote a section of the controller to running a process to determine stopping time and if the braking performance of the motor becomes unacceptable.

D Two cameras; one at each side, may suffice. The inventors prefer use of four cameras to provide useful backup against problems such as splatter on the windows. It also provides for future development of nearer and farther zoning within the surveilled zone. The cost of cameras is small as compared to the cost of injury. Operators should be instructed to periodically clean the windows and the light source.

An antenna 109 may communicate machine status from an internal digital controller to a network. The antenna may be used to (for example) signal an unusually high rate of operator transgressions to a person in charge.

VARIATIONS

Contact sensing using conductive gloves as is commonly performed in the prior art may be retained as a supplementary option. Some workers would be fearful of abandoning the perception of physical security that contact sensing provides. At times the skinner may have to be used with items that are incompatible with the camera-based optical sensing approach described in this document.

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Apparatus responsive to conduction of electricity from any conductive part of the machine, '5 including the blade, through conductive gloves may respond by indirectly generating the SIGNAL, for example if the voltage amplitude of the imposed current falls, or if the current, flowing into the machine as a result of contact between a conductive glove and the blade, changes. For that purpose, the controller of the imaging proximity sensing apparatus as herein described will preferably also provide a glove contact sensing input connection as an "OR" .0 option for creating the SIGNAL carried to the motor controller. As a result, either an image of a gloved hand within the dangerous zone, or an electrical contact will cause the machine to stop immediately.

ADVANTAGES

1. The skinner or derider machine includes an imaging proximity sensing apparatus .5 capable of predicting hand trauma by surveilling a distance of about 10 mm about the blade and taking immediate action to prevent glove-blade contact, rather than being limited to taking action after glove-blade contact has occurred. 2. Machine stopping may be performed more slowly than in the case of a conductive glove contact sensor, and is ideally completed within about 10 milliseconds. 3. In an alternative, a self-braking motor may be fast enough. 4. Absent a cable, the operator has freedom to handle and move the product to be trimmed across the feed roller for optimum performance.

It will be understood by persons skilled in the art that the embodiments described in this specification are to be considered as illustrative and not restrictive. Such persons will appreciate that variations can be made within the scope and spirit of the invention.

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Claims

WE CLAIM

1. A power-operated skinner machine having a fixed blade and including safety apparatus and used for shaping an item of flesh that is brought up to the blade by an operator's hand or hands; the machine having a chassis and having a blade mount located above and parallel to a rotatable gripping roller driven by a motor, the item being advanced, when in use, at a feed velocity and in a direction toward a front edge of the blade by the gripping roller, characterised in that the machine includes imaging proximity sensing apparatus incorporating at least one video camera with a lens and adapted to detect the operator's hand or hands and if, when in use, an image of said hand is detected as being inside a volume previously determined to be located in a dangerous proximity to the blade, the imaging proximity sensing apparatus makes and .0 transmits a SIGNAL capable in use of causing a motor control apparatus to actively stop the motor, thereby halting the gripping roller and rendering the machine safe.

2. The skinner machine as claimed in claim 1, wherein the dangerous volume is located parallel to an axis of the gripping roller and parallel to the elongated blade, along and above the gripping roller and in front, relative to a position of the operator, of the .5 blade.

3. The skinner machine as claimed in claim 2, wherein the imaging proximity sensing apparatus is optimised for detection of an operator's gloved hand; said hand being covered by a glove having a contrasting optical signature to that of a remainder of the view of the camera.

4. The skinner machine as claimed in claim 3, wherein the imaging proximity sensing apparatus is adapted to provide a warning if the operator's hand is detected inside the surveilled volume and outside the dangerous volume.

5. The skinner machine as claimed in claim 1, wherein the imaging proximity sensing apparatus employs a plurality of video cameras each of which receives a view along the surveilled volume and the proximity sensing device is configured to generate the SIGNAL if at least one video camera detects a portion of the operator's hand apparently in unsafe proximity to the blade.

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6. The skinner machine as claimed in claim 5, wherein the imaging proximity sensing apparatus further includes apparatus responsive to conduction of electricity from any conductive part of the machine, including the blade, through conductive gloves; said apparatus being adapted to also generate the SIGNAL in event of conduction being detected.

7. The skinner machine as claimed in claim 5, wherein the imaging proximity sensing apparatus is provided with two cameras concealed on each side of the machine; the fields of view of all the cameras being directed along the surveilled volume through windows adjacent both ends of the gripping roller.

8. The skinner machine as claimed in claim 5, wherein the imaging proximity sensing apparatus includes an optical assembly behind each window; each optical assembly comprising a sealed tunnel having a length and transparent windows thereby .0 permitting use of a longer focal length imaging lens for each camera that has an effect, when in use, of extending a depth of focus within the surveilled volume and the dangerous volume.

9. The skinner machine as claimed in claim 5, wherein the motor of the gripping roller comprises a controllable motor capable of bringing the roller to a halt within 10-15 .5 milliseconds after a motor controller connected to the motor receives the SIGNAL and makes the motor stop turning.

10. The skinner machine as claimed in claim 5, wherein the motor of the gripping roller comprises a self-braking induction motor capable of bringing the roller to a halt within 100 milliseconds after interruption of power to the motor in response to the SIGNAL.

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