Cutting disc stop device

Abstract

The machine operator holds the chicken carcass on the circular saw or the casting on the abrasive cut-off wheel. Significant risks to the hands are minimized by a controllable (approximately 10 ms) wheel stop mechanism, optically activated when a gloved finger enters the danger zone (optionally, a conductive glove trigger is used). An electromagnet releases a powerful spring mechanically linked to the opposing brake shoes, pressing them against either side of the brake disc. The brake disc and cut-off wheel share a shaft but are located in separate compartments. Further features include incident reporting via a network.

Description

[Technical Field]

[0001] The present invention provides a device for quickly stopping the rotation of a motor-driven cutting disk or wheel, such as a circular saw or abrasive cut-off wheel, in a cutting machine. Stopping the disk can protect the operator's hands from injury. The present invention more generally relates to machines in which a hazardous situation detector is connected to a disk brake device capable of quickly stopping the shaft. [Background technology]

[0002] <Definition> "Brake stop" in the present invention refers to a procedure for quickly stopping the cutting disc or wheel. "Fast" or "rapidly" is defined herein as "a total pause time of less than 20 milliseconds." The times specified are examples. Longer time intervals can also be provided by the same mechanism. "Circular saw" or "disc saw" refers to a rotatable disc that may have cutting edges (blades) or circumferential teeth, which may be knife edges, for cutting an item into portions. Such machines and cutters are widely used in meat and poultry processing plants to separate carcasses into portions. "Abrasive cut-off wheel" refers to a self-sharpening abrasive wheel that is typically thin and contains reinforcing fibers.

[0003] Cut-off wheels (including circular saws or disc saws) are widely used in industry, for example, for cutting wood or plastic, as well as for butchering carcasses in the food industry. Unlike carpenter's bench saws, the entire disc may be exposed. Operators of disc saws used in meat or poultry plants are constantly at risk of serious hand injuries. This is shown in the YouTube® video: https: / / www.youtube.com / watch?v=KOyc65T50pY (last downloaded on January 15, 2024). The disc saw device described below can help mitigate this risk.

[0004] The applicant has already disclosed optical monitoring devices of this type in cutting machines, for example in patent application WO 2016 / 032345 and patent application WO 2023 / 287304.

[0005] US Patent Application Publication No. 2010 / 011926 describes optical detection but does not describe an equivalent mechanism for stopping the blade of a circular saw.

[0006] U.S. Patent Application Publication No. 2017 / 0312837 describes conductive detection of glove proximity for a circular saw. All stopping options apply to the saw blade. One stopping option uses a pyrotechnic device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2016 / 032345 Brochure [Patent Document 2] International Publication No. 2023 / 287304 Brochure [Patent Document 3] US Patent Application Publication No. 2010 / 011926 [License 4] U.S. Patent and Trademark Office Publication No. 2017 / 0312837 [Non-licensed literature]

[0008] [Non-licensed Document 1] How to cut a whole chicken (Hygienic machine cut), [online], [Reiwa 6 January 15th], インターネット <url: https: www.youtube.com watch?v="KOyc65T50pY"> Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object of the present invention to provide an apparatus and method for quickly stopping a cut-off wheel in response to an event that may result in injury to an operator's hand, such as the detection of a hand being optically brought into close proximity with the cut-off wheel. [Means for solving the problem]

[0010] In a first broad aspect, the present invention provides a hazard response device for inclusion in a disc cutting machine of the type including a motor and a rotatable cutter shaft rigidly supported from a frame by bearings which support a cutting disc in a working area, the cutter shaft having sides and also fixedly supporting a separate brake disc disposed in a space between opposing sets of brake pads mounted on the frame, the hazard response device being adapted, in use, to effect a first effector in response to a detected hazard by releasing energy stored in a spring, so that action of the spring causes a linkage to act on at least one movable brake pad and press the pad against a side of the brake disc, thereby creating friction during braking and causing the cutter shaft and cutting disc to stop rapidly within a controlled time.

[0011] Preferably, the brake disc is supported from the cutter shaft in a compartment separated from the working area.

[0012] Alternatives for cutting discs or wheels are selected from a range including cut-off wheels with knife edges, cut-off saws with teeth around the edges, and grinding or cutting wheels.

[0013] Preferably, the first effector is selected from a range including a reversibly closeable magnetic circuit and an electromagnetic trip device acting on the over-center latch, the first effector providing a rapid release of energy to the linkage when actuated.

[0014] Preferably, the linkage includes a brake arm pivotally connected to the spring and rigidly coupled to a rotatable stub axle supported on the frame, the stub axle being rigidly coupled to a moveable brake pad.

[0015] Preferably, the restoration of the energy stored in the spring is provided by a prime mover selected from the range including an electric motor, a hydraulic piston, and a pneumatic piston, which returns the cutting machine to a safe and stoppable state before the cutting machine is used.

[0016] In the first option, the cutter shaft is driven directly by the motor.

[0017] In a second option, the cutter shaft is indirectly driven by a flexible drive selected from a range including belt drives and timing belt drives, which operatively couples the cutter shaft to another shaft driven by a motor.

[0018] In a second broad aspect, a monitoring device capable of detecting a dangerous situation in use includes a camera and lens capable of forming at least one image of a dangerous area including a predetermined area around a cutting disc in use, the camera and lens being capable of detecting an image of an object having a predetermined characteristic appearance within the dangerous area and, if detected, activating a first effector.

[0019] Preferably, the detected image is differentiated from the background by an image analyzer that receives images from the camera, and the characteristic appearance is selected from a range including the characteristic colors of blue gloves, green gloves, yellow gloves, red gloves, fluorescent gloves, and infrared fluorescent gloves worn by the worker.

[0020] In one option, the monitoring device includes a device capable of detecting electrical contact between a conductive glove worn by an operator and wired to sensing means within the device and a portion of the machine including the cutting disc, which contact activates the first effector.

[0021] In an auxiliary aspect, the monitoring device comprises evaluation means for evaluating the elapsed time taken after detection until the cut-off wheel stops and for preventing use of the machine if the evaluated time exceeds a predetermined limit value.

[0022] In a further aspect, the monitoring device capable of detecting a dangerous situation in use also includes a second effector, the second effector including a digital incident reporting system configured to prepare and transmit a detailed incident report to a server over a network when triggered to respond to the danger.

[0023] Preferably, the control time for the braking action itself is in the range of 2 to 15 milliseconds.

[0024] <Notes> The description of the invention herein is provided purely by way of example and is not intended to limit the scope or extent of the invention. In particular, references to a "disc saw" or a "cutting wheel" are merely exemplary for the purpose of explaining the invention, and the invention is applicable to other rotary cutting machines. The numbers in the drawings are not limiting with respect to the description in the specification or claims.

[0025] The invention has been described in an illustrative manner, and it is to be understood that the terminology used is in the nature of description and not of limitation.

[0026] Throughout this specification, unless otherwise specified in the context, the terms "comprise" and variations such as "comprising" or "comprises" are understood to mean the inclusion of a specified integer or step or group of integers or steps, but not the exclusion of other integers or steps or groups of integers or steps. Each publication, reference, patent application, or patent cited herein is expressly incorporated herein by reference in its entirety.

[0027] Reference to cited material or information cited in the text is not to be understood as an admission that the material or information was or was part of the public knowledge in New Zealand or anywhere else. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 10 is a perspective view of the active area and monitoring extension above it on a dual axis version of the stand-alone machine. [Figure 2] FIG. 4 is an explanatory diagram showing a cutter shaft. [Figure 3] FIG. 1 is a conceptual diagram showing a brake mechanism using an electromagnet. [Figure 4] FIG. 10 is a rear view showing the spring, its frame, and the brake mechanism. [Figure 5] FIG. 4 is a detailed view showing the brake pad relative to the brake disc as seen obliquely from the front. [Figure 6] FIG. 1 is a front view of a preferred brake disc. [Figure 7] FIG. 1 is a cross-sectional view showing a resilient mount for a brake disc. [Figure 8] 10 is a schematic diagram showing connections in a second embodiment (network). DETAILED DESCRIPTION OF THE INVENTION

[0029] First Embodiment The illustrated two-axis machine mimics existing disc saws used to separate poultry carcasses into two or more pieces, while adding safety features. The illustrated machine is adapted to quickly and non-destructively brake the cutting disc to a stop if an emergency stop is determined to be necessary. Operator safety measures include a monitoring device to detect events (primarily related to the operator's hand movements) that require the cutting disc to be stopped. This specification describes a complete or integrated machine with a cut-off wheel or cutting disc. The illustrated machine has a first effector with an internal device for stopping the cut-off wheel and an optional second effector with networked activity reporting means.

[0030] <Overall design of poultry disc cutting machine> Referring to FIG. 1, a stand-alone poultry disc cutting machine 100 has a cutting disc including a cutting wheel 107 located within an open work area or space 102. A shroud 108 covers a rotary drive or cutter shaft 201 that leads to a cantilevered blade. The cutter shaft is supported by bearings within the machine. The blade is fixed in place within the machine and mounted at a convenient height for a standing operator (not shown), who typically holds the carcass by hand before and during the cutting operation. Passive guide rods 106 are commonly used in machines of the type shown to help guide the poultry carcass toward and away from the blade and to support the carcass at the rotating blade edge against forces exerted by the cutting action.

[0031] The operator has a series of control buttons 105 to start and usually stop the machine, and there is also a status display 104. The floor mounted support legs are indicated by reference numeral 103 and within the working volume 102 is provided a splash guard or protective shield 109 for the cut-off wheel 107.

[0032] <Partition> Unlike some prior art, the brake is not applied to the cut-off wheel 107 itself. The work area 102, including the blade, can be considered an open compartment. A panel 208 (see FIG. 2) isolates the environment of the brake compartment 200, located to the left of the shroud 108, from the space 102, thereby (1) keeping sawing debris, such as fat, away from the friction brake, (2) preventing cleaning fluids from entering the machine interior, (3) protecting the operator from the cutter shaft drive and components that are forced to energize when the brake is activated, and (4) cooling, depending on the work environment and workpiece, the brake compartment 200 can be heated to prevent condensation.

[0033] <Trigger Event> In addition to power-off and normal shutdown as commanded by the operator using the "Stop" button 105, a quick brake shutdown (including cutting disc) can be performed in response to the following trigger events: a. When a machine vision system detects that an operator's hand wearing a colored glove is too close to the cut-off wheel according to the predefined settings. This will initiate a brake stop. See below. b. Electrical contact detection (optional) when an operator wearing conductive gloves makes electrical contact with the cut-off wheel. Visual and electrical detection can coexist. A wired connection from the operator's hand to the machine is required. See below. c. When the power supply to the entire machine is interrupted internally or externally. d. When a fault is detected by the machine's self-monitoring of braking performance.

[0034] The trigger events that initiate the brake stop are "ORed." During normal operation, the stored energy device, a powerful spring, is held in compression by an electromechanical device, either directly by the electromagnet armature (first embodiment) or by a retaining finger that is extended and held in place by the electromagnet using an over-center linkage (second embodiment). The trigger is activated by interrupting the current through the electromagnet, instantly releasing the spring. The resulting spring movement forces a pair of brake shoes against either side of a metal brake disc. In accordance with the present invention, the brake disc and cut-off wheel or disc are separate and located in separate compartments.

[0035] <Monitoring equipment: visual or optical monitoring system> For operator safety, an optical monitoring system is mounted above the work area 102 and in association with the cut-off wheel 107. A preferred version uses a shroud with a mirror 101 that extends toward the operator and reflects a top-down view of the cut-off wheel 107 to an internal camera. If a colored-gloved hand is detected within a predetermined danger zone near the blade or cut-off wheel, an image analyzer quickly generates a trigger event or signal, which initiates a rapid "brake-to-stop" process, as described below.

[0036] Hand proximity detection, as opposed to actual hand contact detection, is advantageous because it reduces the risk of injury to the operator and allows additional braking time. Associated software establishes precise boundaries of the intangible danger zone surrounding the blade toward the operator's position and to each side.

[0037] WO 2023 / 014232 (PCT / NZ2022 / 050094) is a pending document that describes generating four spaced-apart viewpoints of a work area 102, which are aggregated by a series of mirrors and focusing lenses onto the image sensor of a single machine-vision color camera as four adjacent but separate images. An image analyzer is adapted to reference any image on the image sensor and identify pixels representing a gloved operator's hand within the hazardous area surrounding the imaged cutting disk. Recognition requires appropriate program constants, such as hue discrimination, to distinguish "glove pixels" in the image by a different color or brightness from "background pixels" originating from the workpiece or machine. In the food industry, operators are typically required to wear blue or green gloves. These colors provide contrast against meat. Red gloves may be used for wood saws and yellow gloves for fish saws. Alternatives include visually fluorescent gloves, as well as gloves with infrared contrast (possibly from fluorescence) visible to selected cameras. The disc cutting machine has ample lighting in the work area, including lighting that excites the fluorescent gloves.

[0038] The extent of the danger zone is preferably interpreted as "less than 20 mm from the wheel" in the case of a cut-off wheel. This distance may be different on the left and right sides of the cutter. It depends on the speed of the unintentional movement of the hand and the total reaction time of the machine. For example, in this invention, the designer can evaluate how far the hand can move during a typical total reaction time of 10 ms and set the danger zone at twice that distance as a safety margin. The outline of the danger zone is a rectangular parallelepiped with relatively vertical edges, including the cutting disk.

[0039] <Timing> This section also applies to the second embodiment. The image analysis process can take 2-4 milliseconds, depending on the camera frame refresh rate, for example. The release of the spring 304 then begins 2 milliseconds later, and the rotary disc cutter can finally stop within 5 milliseconds. An immediate brake stop can take a total of 9-11 milliseconds. The inventors' experience with band saw safety suggests that thumb slippage, operator distraction, and fatigue are likely the primary causes of brake stoppage. Hand movement can take up to approximately 2 milliseconds. -1 , or 2 mm per millisecond. A response time of 10 ms is sufficient for a danger zone boundary set at 20 mm from the cutting edge. When the visual form of the present invention is used, a gloved hand will not come into contact with the edge during operation.

[0040] <Glove Electrical Contact Options> Optionally, conductive gloves are worn and connected, such as by conductive wires, to a current source referenced to the machine chassis 100. The onset of conduction between the gloves and the cutting disc can be indicated by a sudden change in the voltage supplied by the machine. A sufficient change (preferably distinct from that caused by contact with a grounded workpiece) will cause a brake trip. It has been noted that operators who use conductive gloves with disc cutters are reluctant to change to simple blue latex gloves. The machine vision system and conductive glove system can be used simultaneously. Either optical or conductive sensing will cause a brake trip.

[0041] Those skilled in the art may choose to rely solely on electrical contact in the glove. The present invention relates to a brake-stop mechanism that has a faster stopping time than the prior art (at least in a non-destructive manner). The total time does not include the 2-4 ms for image analysis, which can take as long as 7 ms, a fraction of a full rotation.

[0042] <Motor and belt> In one option, a cutter shaft 201 supported by bearings has a drive pulley, brake disc, and cantilevered cutting disc mounted near one end. The other shaft, which has a drive pulley for driving the belt, is rotated by, for example, a conventional AC shaded pole induction motor (not shown) rated at about 750-1500 watts. When supplied with 50 Hz AC power, the speed is about 1500 revs.min. -1 It is preferable to minimize the rotational inertia of the motor as much as possible. A smaller, somewhat lower-power induction motor can be selected. Induction motors with an iron cylinder rather than a solid armature have lower rotational inertia. In either embodiment, a motor with low rotational inertia can be used, such as a brushless DC motor with a permanent magnet armature (e.g., a 600-watt Brushless-D110BLD600-48) or a 600-1000-watt air turbine motor (Air Turbine Tools, Boca Raton, FL). These have not been tested.

[0043] In a first embodiment, both shafts support toothed pulleys engaged with timing belts. One suitable belt is a toothed reinforced rubber timing belt (general purpose type: HTD-8M, 50 mm wide) containing glass fiber tensile cord and a neoprene body. When the machine executes a braking stop, all rotating parts (including the motor via the belt) stop simultaneously.

[0044] As part of the braking shutdown, the motor power is cut off. The inventors have noted that self-braking motors that include internal brakes that activate when power is removed are too slow when used alone. Furthermore, such brakes can be disconnected from the blades on other shafts by a broken belt, so if the belt breaks during self-braking, the cutter shaft and cutting disc will not stop.

[0045] <Cutter shaft> The cutter shaft is a rigid shaft because it generates significant braking forces. Figure 2 shows a front view of the shaft 201 and its cantilevered extension 201A, which supports the cutting disc 107. First and second bearings 202, 203 support the cutter shaft relative to the machine chassis (not shown). The brake disc 205 is aligned with closable brake pads 206, 209, and the toothed drive pulley 204 is aligned with the toothed drive pulley 418 on the first shaft to receive the drive belt. Both shafts typically rotate at approximately 1500 rpm. The cutter shaft experiences significant braking forces when rotating at normal rotational speeds. The brake disc 205 also transmits force to the cutter shaft. Energy, often in excess of 100 kW, is extracted from the cutter shaft and converted to heat.

[0046] 2 shows, for the first embodiment machine, one way of assembling the cutter shaft 201: an elongated machine screw with a head 207 at the left end of the shaft 201. When the shaft is removed for occasional belt or brake disc replacement, the machine screw can be unscrewed. The left portion of the shaft 201, down to the brake disc 205, can then be removed and serviced from the mostly hidden right portion 201A.

[0047] Second support bearings (203) are provided. Preferably, one bearing prevents axial movement of the shaft and the other (e.g., a roller bearing) allows axial movement of the shaft. In Figure 2, bearing 203 is partially hidden by shroud 108 located on the working side of plate 208, which also separates the compartments (see above). Triangular shaped items 206, 209 are brake shoes or brake pads. 412 denotes a stub axle that is part of the brake pad linkage.

[0048] The shroud 108 is supported from the panel 208 and covers a cantilevered extension that extends into the working area towards the cut-off wheel 107. The shroud 108 supports a protective shield 109 around the blade.

[0049] <Brake pads> Suitable pad materials are selected from a range including cast iron, stainless steel, copper, phosphor bronze, or other forms of bronze. Automotive pads with fibrous materials embedded in phenolic or acrylic resins are also being tested. Brake discs and brake pads are where a large amount of kinetic energy is converted into heat in a matter of milliseconds.

[0050] <Physical installation of springs and brake pads> The compression spring 304 stores force to close the brake pads around the brake disc 205 when braking.

[0051] The brake pads face each other. Pad 209 is rotatable about the stub axle and pads 209 and 206 are pressed together by the pressure of spring 304 which is quickly released via a linkage when braking is stopped. It has been found convenient to fix brake pad 206 in place.

[0052] FIG. 3 is a simplified diagram illustrating the principle of a preferred fail-safe brake mechanism, similar to a magnetic lock on a security door. It is called "fail-safe" because current continues to flow while the cutting disc is rotating. As shown, the state is "cut mode; brake released; electromagnet energized." In this case, the spring release is cocked, and contact between the brake disc 205 and the brake pads 206, 209 is prevented by the holding action of a magnetic field generated by continuously applying current to the windings 305, 306. This magnetic field circulates within a magnetically permeable soft electromagnet core 301 (see hatched area) and a movable armature 303. The armature is held against a soft ferromagnetic U-shaped (or pot-shaped) core by the attractive force of the magnetic field.

[0053] When the current in the windings 305, 306 is interrupted, the energy stored in the compression spring 304 pushes the armature 303 to the left, rotating the brake pad 209 and applying a high but controlled braking force to the cutter shaft 201. The braking force is set by the spring. The spring surrounds a shaft 307 that is fixed to the armature and is supported away from the windings. The shaft is pivotally connected to a movable brake pad 209 to absorb wear. The fixed brake pad 206 is also pivotally mounted to the machine frame.

[0054] 3 also shows reset cam 308. This cam is rotated 180° by a reduction gear reset motor (not shown) and presses with great force against pivotally mounted bar 309, drawing shaft 307 into the electromagnet and compressing the spring. The electromagnet current is then turned on, maintaining the spring in compression. The cam rotates another 180° back out of the way of bar 309 before the brake is reapplied. The electromagnet housing includes fins for heat dissipation.

[0055] <Power off> In either embodiment, a "fail-safe" design ensures that if the actively maintained electromagnet current is interrupted for any reason, such as a general power outage or a machine power failure, the armature 303 will be released and a brake stop (which does not require a power supply) will be effected. If a brake stop is not required, the operator simply presses the "OFF" button to remove power to the motor, causing the rotating cut-off wheel to gradually slow down.

[0056] <Brake discs and their installation> FIG. 6 is a front view of the brake disc 205. The brake disc 205 is constructed of a metal such as steel or stainless steel. In the illustrated embodiment, the disc is approximately 5 mm thick and 100-120 mm in diameter. Splines 602 around the central opening of the brake disc transmit braking torque to the sides of corresponding splines formed on the cutter shaft during braking. The brake disc may include multiple holes 603 to promote air circulation to aid in heat dissipation and reduce rotational inertia.

[0057] FIG. 7 shows a cross-sectional view of a portion of a self-centering resilient mount that allows lateral movement of the brake disc 205 while maintaining positive engagement between the splines during braking. The inventors discovered that it was convenient to move only one brake pad (see below), which resulted in the brake disc tending to twist during use due to uneven pad movement. Two O-ring mounts 702 and 705 include concentric grooves for O-rings 703 and 704, respectively. Each O-ring compresses against the brake disc adjacent its complementary spline, thereby providing torsional resilience. The adjusting ring can be held in place with a lock nut 701. Splines on the brake disc are used to prevent relative rotation on the cutter shaft.

[0058] The machine chassis 100 provides a rigid support for the fixed brake pads 209, the support bearings for the stub axle 412, and the bearings for the cutter shaft 201 which support the brake disc 205 and the cutting disc 107. The chassis can be made from 10 mm thick steel plate by bending and welding to increase its strength.

[0059] Second Embodiment FIG. 4 shows a rear view of a sturdy frame 400 containing a stronger coil spring 304 (nominal compression 650 pounds per inch (11,600 kg per meter)). The frame is configured as two connections 402, 403 and secured to the machine frame by bolts 401A, 401B, 401C, 401D. Straps 418 reinforce the frame. Frame 400 is mounted vertically within the disc cutter machine. Frame 400 supports the force that closes the brake pads around the brake disc via the brake arms.

[0060] <Springs and cocking> The spring 304 surrounds a telescoping guide shaft 410 and is confined between end stops. One stop is a pneumatic tension or cocking cylinder 408. The spring force is typically about 2000 N, and the force transmitted to the brake pads is amplified by mechanical leverage provided by the dimensioning of the brake arm and shaft around a stub axle 412, shown in Figures 2, 4, and 5. The cylinder 408 is fixed to the frame 402 in a pivotable mount 405. The other stop is located on a variable collar 415, which is adjustable to vary the spring length and transmitted force. The movable end is pivotally held via a pivoted clevis at 406 to a brake arm or beam 411, which is rotatably supported by the attached stub axle (end 412). The cylinder 408, telescoping guide shaft 410 inside the spring 304, and clevis 407 pivot as a unit from the brake arm during cocking and release. A protrusion or tang 417 on the side of the clevis is restrained against the spring force by an extension finger 413 held in place by an over-center mechanism that is held in place by the current in an electromagnet 419.

[0061] Unlike the first embodiment, the full force of the spring is not held directly, so a relatively low power electromagnet 419 is used. An over-center release mechanism within the housing 414 uses a relatively small electromagnet current to hold the finger in place against the spring.

[0062] <Release> When the current at 419 is terminated, the finger is retracted, forcing the released spring 304 to extend, which causes the pivot 406 and brake arm or beam 411 to move clockwise (see FIG. 4) about the stub axle, rotating the rigidly connected brake pads 206 (see FIG. 5). A partially hidden brake disc 205, held by a partially hidden cutter shaft 201, is clamped between the two pads. The spring force is effectively amplified at the stub axle 412 by the ratio of the length from the pivot of the brake arm 411 to the stub axle 412 divided by the length of the moveable brake pad 206 from the stub axle axis. The friction area of ​​each brake pad is approximately 800 mm 2 is.

[0063] An advantage of the present invention is that the brake operates with a predetermined force set by the characteristics of the compression spring 304, the amount of spring restraint, and the ratios described above. The duration of the brake can be controlled from about 2-4 ms or longer by adjusting the spring pressure using the collar 415 or by using a weaker spring. Braking is not a catastrophic event. As discussed in the "Timing" section above, the brake duration can be extended by using optical proximity sensing rather than contact sensing.

[0064] 5 shows a perspective view of a portion of frame 501, including movable brake pads 206 and fixed pads 209. In this case, these pads are located on either side of brake disc 205 (not shown), which occupies space 205A. 502 is a cover over the bearings that surrounds and supports the stub axle. Castings 503 provide end supports for these bearings. The stub axle transmits the rotation of brake arm 411 to pads 206. A relatively long and sturdy stub axle is advantageous because, together with the bearings, it is subjected to high forces during use.

[0065] In the illustrated embodiment, there is no lateral resilience between the brake disc 205 and the cutter shaft 201. The disc is bolted to a collar that surrounds the shaft. The disc may flex during braking.

[0066] A suitably rated and transient protected solid-state switch, such as a power MOSFET, can be connected to short the coil of the electromagnet when the control electrode is turned on, accelerating the collapse of the magnetic field in the electromagnet and quickly dissipating the induced power in the resistance of the windings, causing the fingers 413 to quickly retract.

[0067] <Internal check> The machine may include transducers for monitoring and safety purposes, such as to report drive shaft rotation, cutter shaft rotational and stopping speeds, linear movement of spring 304 (or strain gauges can be used to report spring compression), and operation of movable brake pad 209. If the brake stops take too long, it is unsafe. In this case, the machine is taken out of service until the cause is identified and corrected by repair (service) personnel. After a predetermined number of emergency stops, a regular service call may be made.

[0068] The inventors have found it useful to control each disc cutter from an internal industrial PC with sufficient capacity to manage functions such as test runs, operator control and monitoring, and essential image processing. The PC drives the operator display 104. The PC preferably runs frequent self-test procedures in case a component failure could lead to a dangerous condition.

[0069] Data and Reporting This "second effector" or management safety function is a useful feature for the disc cutter. As shown in FIG. 8, the internal PC of the disc cutter machine 100 can immediately report to the local server 800 having a supervisor display 802 via the local network 801 each time the braking function occurs. The report can be further transmitted to another server 804 via another network 803. Each disc cutter can have its own URL or Internet address. Each report usually includes reports of the operator and the machine, location, date and time, environmental conditions, motor load, and may further include a short video of the images collected before each brake stop. For example, a supervisor having a display dashboard 802 is notified when an operator makes an abnormally large number of brake stops during a shift. In this case, the supervisor can take corrective measures. The playback of the video can be evidence that an injury has been avoided. For this purpose, the industrial PC is programmed to save the latest set of analyzed images as a video clip for reporting.

[0070] <Example of PC processing steps> 1. The work area is illuminated (in this case, it is assumed that the operator has entered his name). 2. The "nearest brake stop time" is checked. If the machine cannot brake quickly enough, its use is stopped until it is repaired. 3. The machine vision device is self-checked or the hand of the gloved operator is checked by approaching the edge of the stationary cutting wheel. The proximity detection at this time can include an audible signal or a visual signal, or both signals. If normal, the operation can be started. 4. During the use of the machine, the current of the electromagnet is maintained and the spring is held in a compressed state by holding the finger 417 in the extended position. 6. The motor of the cutting wheel is activated and the cutter is used. 7. The process stops either by retracting the finger 417 together with a brake stop or by a normal stop.

[0071] <Sequence of steps for braking to a stop> 1. When the machine vision system detects a hazardous situation, such as capturing an image of part of a gloved hand within a threshold area around the cutting disc, an internal signal is generated that determines whether a brake stop should be performed (electrical conduction can also be sensed). 2. When the holding current of the electromagnet 419 is cut off, the spring 304 is released and the beam 411 moves along an arc around the stub axle 412, causing the movable brake pad 209 to press the brake disc against the fixed brake pad, quickly stopping the cutter shaft. 3. The motor drive power is also cut off. The time to stop is compared to a predetermined value to ensure that the machine stops quickly. 4. The device is ready to perform the start step again.

[0072] <Other embodiments> To make the stopping time faster, a larger spring force is applied to the brake pads, or different pads are used that are always stressed by the machine frame. To make the stopping time slower, a smaller force is used. For example, the force amplification provided by the spring strength or amount of preload, the brake pad material, or the particular shape of the lever arm or pivot point can be changed.

[0073] The motor can be connected directly to the cutter shaft supporting the cutting wheel, or via an elastic in-line coupling if no other shaft is used. Suitable motors include brushless DC motors, which have a lower rotational inertia. Air turbine motors can also be used.

[0074] It has been found that at least some abrasive cut-off wheels can withstand rapid braking shutdown.

[0075] <Advantages> The present invention provides a fast enough response time when a gloved operator's hand is detected within the proximity of the cutter blade, stopping the cutter wheel rotation before the hand reaches the blade.

[0076] Optionally, intrusion can be detected by electrical contact with a conductive glove.

[0077] In the event of a power outage, the disc brakes are activated.

[0078] If the belt to the cutter shaft breaks while the brake is off, the machine will remain in a fail-safe state.

[0079] If the transducer detects insufficient spring compression, the machine goes into a "safe state," in which case the motor cannot run, or if the previous brake stop was too long, the motor cannot run until repaired.

[0080] No sacrificial components are consumed during braking and the machine returns to "standby" state within seconds.

[0081] The actual braking time may be longer than the nominal 2-4 ms, and may be longer than on conductive machines, because the hand comes into proximity with the blade before the hand actually makes contact with the blade.

[0082] The brake equipment is located in a separate compartment so that particulate matter from the brake equipment does not enter the work area. Likewise, the brake mechanism does not become contaminated by the material being cut and is periodically cleaned, and the brake compartment can be heated to prevent condensation.

[0083] Finally, it will be understood that the scope of the present invention is not limited to the specific embodiments described and / or illustrated herein. Those skilled in the art will recognize that various modifications, additions, known equivalents, and substitutions can be made without departing from the scope and spirit of the invention as set forth in the claims.< / url:>

Claims

1. A hazard response device included in a disc cutting machine, the disc cutting machine including: a motor; a rotatable cutter shaft, the rotatable cutter shaft supported from a frame by bearings that support the cutter shaft and cutting discs in a working area; In a hazard response device having the cutter shaft also fixedly supports a separate brake disc having sides and disposed in a space between opposing sets of brake pads mounted on the frame; The hazard response device is adapted, in use, to effect a first effector in response to a detected hazard by releasing energy stored in a spring, such that action of the spring causes a linkage to act on at least one movable brake pad, which presses against the side of the brake disc, thereby creating friction during braking and causing the cutter shaft and cutting disc to stop quickly within a controlled time.

2. 2. The hazard response device according to claim 1, wherein the brake disc is supported from the cutter shaft in a compartment separated from the working area.

3. 2. The hazard response device according to claim 1, wherein the first effector is selected from a range including a reversibly closeable magnetic circuit and an electromagnetic trip device acting on an over-center latch, and wherein the first effector, when actuated, provides a rapid release of energy to the linkage.

4. 4. The hazard response device of claim 3, wherein the linkage includes a brake arm pivotally connected to a spring and rigidly coupled to a rotatable stub axle supported on a frame, the stub axle being rigidly coupled to the movable brake pad.

5. 2. The hazard response device of claim 1, wherein a prime mover selected from the range including an electric motor, a hydraulic piston, and a pneumatic piston is arranged in a configuration adapted to restore energy stored in the spring, thereby returning the disc cutting machine to a safe and stoppable state before the disc cutting machine is used.

6. 2. The hazard response device according to claim 1, wherein the cutter shaft is directly driven by the motor.

7. 2. The hazard response device of claim 1, wherein the cutter shaft is indirectly driven by a flexible drive selected from the range including a belt drive and a timing belt drive, the flexible drive operatively coupling the cutter shaft to another shaft driven by the motor.

8. 2. The hazard response device of claim 1, wherein the monitoring device capable of detecting a hazardous situation when in use includes a camera and lens capable of forming at least one image of a hazardous area including a predetermined area around the cutting disc when in use, the camera and lens capable of detecting an image of an object having a predetermined characteristic appearance within the hazardous area, and when detected, capable of activating the first effector.

9. 9. The hazard response device according to claim 8, wherein the detected image is distinguished from a background by an image analysis device that receives images from the camera, and the characteristic appearance is selected from a range including characteristic colors of blue gloves, green gloves, yellow gloves, red gloves, fluorescent gloves, or infrared fluorescent gloves worn by a worker.

10. 2. The hazard response device of claim 1, wherein the monitoring device includes a device capable of detecting electrical contact between a conductive glove worn by an operator and wired to a sensing means within the device and a portion of the disc cutting machine including the cutting disc, the electrical contact causing activation of the first effector.

11. 11. A hazard response device according to claim 8 or claim 10, characterized in that the hazard response device includes evaluation means for evaluating the elapsed time required from detection until the cut-off wheel stops, and for preventing use of the disc cutting machine if the evaluated time exceeds a predetermined limit value.

12. 11. A hazard response device according to claim 8 or claim 10, wherein the monitoring device capable of detecting a hazardous situation in use also includes a second effector, the second effector including a digital incident reporting system configured to prepare and transmit a detailed incident report to a server via a network when the monitoring device is caused to respond to the hazard.

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