US20150075342A1 - Safety mechanisms for power tools, including kickback detection system with torque sensor - Google Patents
Safety mechanisms for power tools, including kickback detection system with torque sensor Download PDFInfo
- Publication number
- US20150075342A1 US20150075342A1 US14/495,248 US201414495248A US2015075342A1 US 20150075342 A1 US20150075342 A1 US 20150075342A1 US 201414495248 A US201414495248 A US 201414495248A US 2015075342 A1 US2015075342 A1 US 2015075342A1
- Authority
- US
- United States
- Prior art keywords
- blade
- workpiece
- table saw
- detection
- reaction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B5/00—Sawing machines working with circular or cylindrical saw blades; Components or equipment therefor
- B27B5/29—Details; Component parts; Accessories
- B27B5/38—Devices for braking the circular saw blade or the saw spindle; Devices for damping vibrations of the circular saw blade, e.g. silencing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D45/00—Sawing machines or sawing devices with circular saw blades or with friction saw discs
- B23D45/06—Sawing machines or sawing devices with circular saw blades or with friction saw discs with a circular saw blade arranged underneath a stationary work-table
- B23D45/065—Sawing machines or sawing devices with circular saw blades or with friction saw discs with a circular saw blade arranged underneath a stationary work-table with the saw blade carried by a pivoted lever
- B23D45/067—Sawing machines or sawing devices with circular saw blades or with friction saw discs with a circular saw blade arranged underneath a stationary work-table with the saw blade carried by a pivoted lever the saw blade being adjustable according to depth or angle of cut
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D47/00—Sawing machines or sawing devices working with circular saw blades, characterised only by constructional features of particular parts
- B23D47/08—Sawing machines or sawing devices working with circular saw blades, characterised only by constructional features of particular parts of devices for bringing the circular saw blade to the workpiece or removing same therefrom
- B23D47/10—Sawing machines or sawing devices working with circular saw blades, characterised only by constructional features of particular parts of devices for bringing the circular saw blade to the workpiece or removing same therefrom actuated by fluid or gas pressure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B5/00—Sawing machines working with circular or cylindrical saw blades; Components or equipment therefor
- B27B5/16—Saw benches
- B27B5/22—Saw benches with non-feedable circular saw blade
- B27B5/222—Saw benches with non-feedable circular saw blade the saw blade being arranged underneath the work-table; Guiding arrangements for the work-table
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B5/00—Sawing machines working with circular or cylindrical saw blades; Components or equipment therefor
- B27B5/16—Saw benches
- B27B5/22—Saw benches with non-feedable circular saw blade
- B27B5/24—Saw benches with non-feedable circular saw blade the saw blade being adjustable according to depth or angle of cut
- B27B5/243—Saw benches with non-feedable circular saw blade the saw blade being adjustable according to depth or angle of cut the saw blade being arranged underneath the work-table
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/081—With randomly actuated stopping means
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/081—With randomly actuated stopping means
- Y10T83/088—Responsive to tool detector or work-feed-means detector
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/081—With randomly actuated stopping means
- Y10T83/088—Responsive to tool detector or work-feed-means detector
- Y10T83/089—Responsive to tool characteristic
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/141—With means to monitor and control operation [e.g., self-regulating means]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/606—Interrelated tool actuating means and guard means
- Y10T83/613—Work guard
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/768—Rotatable disc tool pair or tool and carrier
- Y10T83/7684—With means to support work relative to tool[s]
- Y10T83/7693—Tool moved relative to work-support during cutting
- Y10T83/7697—Tool angularly adjustable relative to work-support
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/768—Rotatable disc tool pair or tool and carrier
- Y10T83/7684—With means to support work relative to tool[s]
- Y10T83/773—Work-support includes passageway for tool [e.g., slotted table]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/768—Rotatable disc tool pair or tool and carrier
- Y10T83/7755—Carrier for rotatable tool movable during cutting
- Y10T83/7788—Tool carrier oscillated or rotated
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/869—Means to drive or to guide tool
- Y10T83/8773—Bevel or miter cut
Abstract
Various safety systems for power tools, and in particular table saws include detection systems for detecting a dangerous condition relative to a blade of the power tool, reaction systems for taking mitigation action in response to detection of a dangerous condition. The safety system may detect, prevent, and/or mitigate a dangerous condition associated with the power tool.
Description
- The present application claims priority as a divisional under 35 U.S.C. §§120-121 to U.S. nonprovisional patent application Ser. No. 13/129,948, filed May 18, 2011, now U.S. patent Ser. No. ______, which claims priority to PCT application PCT/US09/65083, filed Nov. 19, 2009, which claims priority to U.S. provisional application Ser. No. 61/116,098, filed Nov. 19, 2008, all of which are incorporated herein by reference in their entirety.
- Many types of power tools have exposed blades, such as table saws and other cutting tools. Contact between the blade and an object other than the workpiece can be dangerous. Safety systems to mitigate potentially dangerous conditions are continually being developed.
- Various new and improved safety systems for power tools, such as table saws, are disclosed herein. The disclosed safety systems include detection systems for detecting a dangerous condition relative to a blade of the power tool, reaction systems for taking mitigating action in response to detection of a dangerous condition, systems for detecting whether the blade is spinning, systems for detecting kickback of the workpiece, and others. Generally, the embodiments described herein may detect, prevent, and/or mitigate a dangerous condition associated with the power tool.
- In one general aspect, embodiments of the present invention are directed to a table saw that comprises a cutting surface and a motor-driven, rotatable blade for cutting a workpiece on the cutting surface. In one embodiment, the table saw comprises a kickback detection system for detecting kickback of the workpiece during cutting of the workpiece. In addition, the table saw comprises reaction means in communication with the kickback detection system for taking a mitigating reaction in response to detection of kickback of the workpiece during cutting of the workpiece by the kickback detection system. According to various implementations, the kickback detection system comprises an acoustic sensor and a processor in communication with the acoustic sensor. The processor is programmed to recognize a condition indicative of kickback of the workpiece during cutting of the workpiece based on input from the acoustic sensor. In another implementation, the kickback detection system comprises a torque sensor mounted on the rotatable blade shaft and a processor in communication with the torque sensor, where the processor is programmed to recognize a condition indicative of kickback of the workpiece during cutting of the workpiece based on input from the torque sensor.
- In another general aspect of the present invention, the table saw comprises a blade-spin detection system for detecting whether the blade is rotating based on energy from the blade. The blade-spin detection system may be in communication with the reaction means and may provide an output to arm the reaction means when the blade-spin detection system detects that the blade is spinning. According to various implementations, the blade-spin detection system comprises a static electricity charge sensor in proximity to the blade for sensing the static electricity build-up on the blade. In another implementation, the blade-spin detection system comprises: (i) a transmitter proximate to the blade for transmitting radio signals; (ii) a passive electronic circuit on the blade that transmits responsive radio signals when passively energized by the radio signals transmitted by the transmitter; and (iii) a receiver, proximate to the blade, for detecting the responsive radio signals from the passive electronic circuit on the blade. In another implementation, the blade-spin detection system comprises an acoustic sensor and a processor, where the processor is programmed to determine whether the blade is rotating based on input from the acoustic sensor.
- In another general aspect of the present invention, the table saw comprises a sensor connected to the cutting surface for sensing a characteristic of the workpiece during, prior to, and/or after cutting of the workpiece. In various implementations, the sensor comprises a height sensor for sensing a height of the workpiece relative to the cutting surface. In such an embodiment, the table saw further comprises a height adjustment circuit that receives an input signal from the height sensor indicative of the height of the workpiece relative to the cutting surface and outputs a signal to a blade height adjustment mechanism to adjust the height of the blade based on the height of the workpiece as sensed by the height sensor. In another embodiment, the sensor comprises a workpiece conductivity sensor on the cutting surface that detects electrical conductivity of the workpiece. In such an embodiment, the table saw further comprises contact detection means for detecting contact with the blade by an object other than the workpiece. The contact detection means receives an input from the workpiece conductivity sensor, which input is used to determine when to trigger the mitigating reaction means.
- In another general aspect of the present invention, the blade comprises a first electrically conductive blade portion, a second electrically conductive blade portion, and a dielectric between the first and second electrically conductive blade portions. In such an embodiment, the table saw may comprise a contact detection system for detecting contact with the blade by an object other than the workpiece. The contact detection system may be connected to the first electrically conductive blade portion and drive the first electrically conductive blade portion with an electrical drive signal. The processor of the contact detection system may detect contact with the blade by a foreign object based on an electrical signal from either the first or second blade portions. For example, the processor may detect contact with the blade by a foreign object based on an electrical signal from the first electrically conductive blade portion.
- In yet another general aspect of the present invention, the table saw comprises a reaction system for taking a mitigating reaction in response to detection of a dangerous condition relative to the blade when detected by the detection system. In various embodiments, the reaction system comprises a magnetorheological rotary brake connected to the blade shaft that brakes the shaft to thereby brake the blade in response to detection of the dangerous condition by the detection system.
- These and other advantageous safety systems for power cutting tools will be apparent from the description below.
- Various embodiments of the present invention are described herein by way of example in conjunction with
FIGS. 1 to 54 , wherein: -
FIG. 1 is a diagram of a table saw: -
FIG. 2 is a block diagram of a table saw according to various embodiments of the present invention; -
FIGS. 3 and 4 are block diagrams of table saws with blade-spin detection sensors according to various embodiments of the present invention; -
FIGS. 5A and 5B illustrate a table saw blade with magnets according to various embodiments of the present invention; -
FIG. 6 is a diagram of a table saw with an electric generator according to various embodiments of the present invention; -
FIG. 7 is a block diagram of a table saw with a static charge detection circuit according to various embodiments of the present invention; -
FIGS. 8A and 8B are diagrams illustrating a table saw blade with passive electronic components according to various embodiments of the present invention; -
FIG. 9 is a block diagram of a table saw with a variable speed motor according to various embodiments of the present invention; -
FIGS. 10A and 10B are diagrams illustrating a table saw blade connected to a motor; -
FIG. 11 is a diagram illustrating a table saw with a counter-rotating flywheel according to various embodiments of the present invention; -
FIG. 12 is a diagram illustrating a table saw blade comprising multiple pieces with different masses according to various embodiments of the present invention; -
FIG. 13 is a diagram of a high-mass flywheel according to various embodiments of the present invention; -
FIG. 14 is a diagram of a table saw with a moveable throat plate according to various embodiments of the present invention; -
FIG. 15 is a diagram of a table saw with a tabletop that pops up according to various embodiments of the present invention; -
FIG. 16 is a diagram of a table saw blade with elongate, moveable members according to various embodiments of the present invention; -
FIG. 17 is a diagram of a table saw blade with pivoting teeth members according to various embodiments of the present invention; -
FIG. 18 is a block diagram of a table saw with remote warning systems according to various embodiments of the present invention; -
FIGS. 19A and 19B are diagrams illustrating a table saw blade with a reaction system that uses an air bag according to various embodiments of the present invention; -
FIG. 20 is a block diagram of a magnetorheological brake for a table saw according to various embodiments of the present invention; -
FIGS. 21A-B are flowcharts of a process according to various embodiments of the present invention; -
FIG. 22 is a diagram of a table saw blade and motor with a clutch and brake system according to various embodiments of the present invention; -
FIG. 23 is a block diagram of a table saw according to various embodiments of the present invention; -
FIG. 24 is a diagram of a table saw with a trailing edge sensor assembly according to various embodiments of the present invention; -
FIG. 25 is a diagram of a table saw with a conductivity sensor according to various embodiments of the present invention; -
FIGS. 26 and 27 are diagrams of table saws with a sensing table top surface according to various embodiments of the present invention; -
FIG. 28 is a diagram of a segmented table saw blade according to various embodiments of the present invention; -
FIGS. 29 and 30 are diagrams of a table saw blade capacitor according to various embodiments of the present invention; -
FIG. 31 is a diagram of a table saw blade with whiskers according to various embodiments of the present invention; -
FIG. 32 is a diagram of a segmented table saw blade according to various embodiments of the present invention; -
FIG. 33 is a diagram of a table saw with a overhead sensor assembly according to various embodiments of the present invention; -
FIGS. 34-42 are diagrams of table saws with downstream safety members according to various embodiments of the present invention; -
FIG. 43 is a block diagram of a table saw with a height sensor and blade height adjustment circuit according to various embodiments of the present invention; -
FIGS. 44-46 are diagrams of table saws with a workpiece height sensor assembly according to various embodiments of the present invention; -
FIG. 47 is a block diagram of a table saw with an installed retrofit package according to various embodiments of the present invention; -
FIGS. 48 , 49 and 50 are diagrams of a push stick that can be used with a table saw according to various embodiments of the present invention; -
FIG. 51 is a top view of a table saw with a suction feed assembly according to various embodiments of the present invention; -
FIGS. 52 and 53 are diagrams of a kick back detection mechanism according to various embodiments of the present invention; and -
FIG. 54 is a block diagram of a table saw with a torque sensor according to various embodiments of the present invention. - The embodiments of the present invention relate generally to safety systems for power tools having an exposed, moving cutting instrument or blade, such as a table saw. Before describing the various new safety features, an example table saw is described.
FIG. 1 shows one type of exemplary table saw 10. It includes a table (or tabletop) 12 through which acircular blade 14 extends from beneath the table. The table 12 includes athroat plate 13, which includes an elongated slot through which a portion of thecircular blade 14 extends. A workpiece (not shown) may be placed on the cutting surface of thetabletop 12 and be cut by the portion of theblade 14 extending above the cutting surface. The table 12 andblade 14 are supported by ahousing 16 andlegs 18. Thehousing 16 may enclose the mechanics that support, position, and drive theblade 16. Thehousing 16 may also comprise processor-based systems for detecting a dangerous condition relative to the blade, as described below, and/or processor-based systems for detecting the condition of the blade (e.g., whether it is spinning). A motor to drive the blade can be positioned in or outside of the housing. Aswitch 20 may be used to turn the saw on and off, causingblade 14 to spin when turned on. Ahandle 22 may be used to adjust manually the position of theblade 14 relative to the table 12. For example, using thehandle 22, an operator of thesaw 10 may adjust how far theblade 14 extends above the table 12 or how theblade 14 tilts relative to the top (or cutting surface) of the table 12. A user places a workpiece on the table 12 and slides it into theblade 14 to cut the workpiece. Of course, table saws take many different configurations, from large saws sized for industrial use to small saws that can be placed on a bench top or counter, and table saws come with various types of tables and housings. The safety and other mechanism described below may be employed in most any type of table saw, as will be apparent from the description below. -
FIG. 2 is a diagram showing certain features of atable saw 10 according to various embodiments of the present invention.FIG. 2 shows that the table saw 10 may comprise adetection system 30 that may be used to detect a potentially dangerous condition with respect to theblade 14. In the illustrated embodiment, thedetection system 30 may be a processor-based capacitive contact sensing system that detects contact of a foreign object with theblade 14 based on a change in an electrical signal on theblade 14 due to the change in capacitance when the foreign object contacts theblade 14. The processor of thedetection system 30 may be, for example, a digital signal processor, a microprocessor, a microcontroller, or some other type of processor. In such an embodiment, thedetection system 30 operates by driving an excitation voltage onto theblade 14 and detecting the current drawn from theblade 14. This current and/or excitation voltage may show changes in amplitude and phase when theblade 14 comes into contact with an electrically conductive foreign object (such as an operator's hand or finger, as well as work pieces). The characteristics of these changes can be used to trigger selectively the operation of areaction system 32, which takes one or more actions to mitigate the detected dangerous condition. The excitation voltage may be driven onto theblade 14 via anexcitation plate 34, which is capacitively coupled to theblade 14. In such an embodiment, ashield 37 may guard theblade 14 from outside electrical interference, including thetabletop 12. - More details regarding such capacitive contact
sensing detection systems 30 may be found in U.S. patent application Ser. No. 11,481/549, entitled “Capacitive sensing system for power cutting tool,” filed Jul. 6, 2006, and U.S. patent application Ser. No. 12/244,994 entitled “DETECTION SYSTEM FOR POWER TOOL,” filed Oct. 3, 2008, both of which are incorporated herein in their entirety. In other embodiments, thedetection system 30 may comprise two electrodes capacitively coupled to theblade 14. In such embodiments, the drive signal may be copied to one of the electrodes. Contact by an object with the blade may be detected by analyzing the signal from one or both of the electrodes. Thedetection system 30 may also be a proximity sensing system that detects when a foreign object comes near (or proximate) to the exposedblade 14. Examples of proximity sensing systems are disclosed in U.S. Pat. No. 7,421,932, issued Sep. 9, 2008, and U.S. patent application Ser. No. 11/444,712, both of which are incorporated herein by reference in their entirety. Other types of detection systems may also be used, and this application discloses other types of detection systems. - The
blade 14 may be mounted to an arbor orrotatable blade shaft 38. Amotor 40 may drive thearbor 38 to spin theblade 14. Themotor 40 may drive thearbor 38 via one or more belts or gears, or it may use a direct drive. - The
blade 14 may be directly driven by the motor or indirectly driven through the use of one or more drive belts or gears. Thesaw 10 may also comprise (under the table 12) a bevel adjustment mechanism (not shown) to adjust the angular orientation of theblade 14 relative to thetable top 12 by pivoting thesaw blade 14 and motor. Thesaw 10 may also comprise a height adjustment mechanism (not shown) to adjust the cutting depth of thesaw blade 14 by vertical movement of thesaw blade 14 and motor. Example embodiments of the bevel adjustment mechanism and the height adjustment mechanism are provided in U.S. Pat. No. 6,595,096, which is incorporated herein by reference in its entirety. - The
reaction system 32 may serve to mitigate the potentially dangerous condition detected by thedetection system 30 by, for example, braking theblade 14, dropping theblade 14 below thetabletop 12, or any other suitable reaction, several of which are described in more detail below. Oneexample reaction system 32 may use an explosive charge to drive a stopper (or brake) (not shown) into theblade 14, arresting its motion. In addition, or instead, anexample reaction system 32 may drop or collapse a blade support member (not shown) causing theblade 14 to fall below the surface of the table 12. An example blade-drop reaction system is described in U.S. patent application Ser. No. 11/374,319, filed 13 Mar. 2006, which is incorporated herein by reference in its entirety. - In a table saw having a
reaction system 32, it is often important to keep thereaction system 32 operative when themotor 40 powering theblade 14 is turned off, but theblade 14 is still spinning. This is because thespinning blade 14, even though the motor is turned off, still represents a potentially dangerous condition. In one embodiment, as shown inFIG. 3 , the table saw 10 may comprise anacoustic sensing system 300, comprising anacoustic sensor 301, such as a microphone, and a processor 302 (e.g., a DSP or microprocessor). The output of theacoustic sensor 301 may be connected to theprocessor 302, which may characterize the audible and inaudible acoustic energy picked up by theacoustic sensor 301 to detect various operating conditions of the table saw. For example, theacoustic sensor 301 could be positioned near, but spaced from, theblade 14, preferably under thetabletop 12 as shown inFIG. 3 , to detect whether theblade 14 is spinning. Theacoustic sensing system 300 may be in communication with thereaction system 32. In operation, theprocessor 302 may compare the acoustic waveforms detected by thesensor 301 to a database of signature waveforms indicative of various conditions of the table saw 10 in order to detect various states or conditions of the table saw, such as whether theblade 14 is spinning or not. If, for example, theacoustic sensing system 300 determines that theblade 14 is still spinning based on the comparison of the signals from the acoustic sensor of the database of signature waveforms, theacoustic sensing system 300 may signal thereaction system 32 to remain powered on and operative (e.g., armed). On the other hand, if theacoustic sensing system 300 detects that theblade 14 is spinning slowly, slowing down, or no longer spinning, or if it detects that theblade 14 is about to come to a complete stop, theacoustic sensing system 300 may signal thereaction system 32 to disarm. - The
acoustic sensing system 300 also may be used to detect other conditions, such as potentially dangerous conditions. If theacoustic sensing system 300 detects such a dangerous condition, theacoustic sensing system 300 may send a signal to thereaction system 32 to cause the reaction system to take its mitigating action. Again, theprocessor 302 may compare the input waveforms from theacoustic sensor 301 to a database of signature waveforms to detect a dangerous condition. For example, theacoustic sensing system 300 may be programmed to detect kickback conditions involving the workpiece being cut by theblade 14. If it detects a kickback condition, theacoustic sensing system 300 may output a signal to thereaction system 32 that triggers the mitigating reaction of thereaction system 32. Theacoustic sensing system 300, based on the output from thesensor 301, could also be programmed to detect various other conditions, such as: (i) motor on with no load; (ii) cutting various types of material (e.g., wood, metal, plastic); and (iii) motor off. The detection of these various states could be used to control different systems of the table saw 10. For example, if theacoustic sensing system 300 detects that the motor is off and the blade is not spinning, theacoustic sensing system 300 may disarm thereaction system 32 so that, for example, maintenance of the table saw 10 may be performed without activating thereaction system 32. Of course, in various embodiments, theacoustic sensing system 300 may comprise a number ofacoustic sensors 301 that supply input to theprocessor 302. The data base of the signature waveforms (for blade spin and/or kickback or the other conditions) may be stored in a memory unit that is in communication with theprocessor 302. The memory unit may be, for example, a read-only memory (ROM). In various embodiments the ROM may be integrated with theprocessor 302. - In another embodiment, as shown in
FIG. 4 , the table saw 10 may comprise a blade-generatedairflow sensing system 400 to detect whether theblade 14 is spinning or not. The blade-generatedairflow sensing system 400, as shown inFIG. 4 , may comprise one ormore sensors 401 and aprocessor 402 in communication with thesensors 401. Thesensor 401 may include one or more airflow detection sensors, such as, for example, pressure sensors or hot wire anemometers, that detect airflow generated by theblade 14. To enhance the airflow from theblade 14, theblade 14 may comprise a number of off-center holes therethrough (i.e., holes that are not in the center of the blade and that are not used for the blade shaft). Thesensors 401 may detect the airflow generated by the blade teeth and/or the holes in the blade. Theprocessor 402 may be programmed to detect conditions based on the output signals from thesensors 401, such as whether theblade 14 is spinning or not. If theblade 14 is spinning, the blade-generatedairflow sensing system 400 may signal thereaction system 32 to remain armed. If the blade-generatedairflow sensing system 400 determines that theblade 14 is not spinning, it may signal thereaction system 32 to disarm. Again, theprocessor 302 may detect whether the blade is spinning by comparing the signals from theairflow sensors 401 to a database of signature waveforms that are indicative of whether the blade is spinning or not. - In another embodiment, one or more vibration sensors (e.g., accelerometers) may be used to detect whether the blade is spinning. Such vibration sensor may be mounted to the
saw 10 in a position relative to the blade so that they vibrate in a detectable manner when the blade spins. - In another embodiment, as shown in
FIGS. 5A-B , one ormore magnets 502 may be embedded in or placed on the exterior of theblade 14. In addition, aninductor 504 may be positioned near theblade 14, such as in thetabletop 12 or under thetabletop 12. As theblade 14 spins, the spinningmagnets 502 will induce a voltage across theinductor 504. The level of the voltage across theinductor 504 may be used to control whether thereaction system 32 is armed or not. For example, the inductor voltage may be coupled to a control circuit 505 (analog or digital) that controls whether thereaction system 32 is armed based on the inductor voltage. If the inductor voltage level exceeds a threshold level, thereaction system 32 may be armed. If the inductor voltage level does not exceed the threshold level, thereaction system 32 may be disarmed. - In another embodiment, the inductor voltage may directly power the
detection system 30 and/or thereaction system 32 with a power converter (not shown) that converts the inductor voltage to input voltage for thedetection system 30 and/or thereaction system 32. That way, thedetection system 30 and/or thereaction system 32 are only powered on so long as theblade 14 is spinning. In such embodiments, thedetection system 30 and/or thereaction system 32 may comprise their own, respective, energy storage device to maintain sufficient continuous power levels. - In another embodiment, as shown in
FIG. 6 , anelectric generator 602 may be positioned under thetabletop 12 and mechanically powered by thespinning blade 14. Thegenerator 602 may convert this mechanical energy to electricity, which may be used to power thedetection system 30 and/orreaction system 32. As shown in the embodiment ofFIG. 6 , thearbor 38 may include agear 604, which is geared into agear 606 for thegenerator 602. As shown inFIG. 6 , there may be one or moreintermediary gears 608 between thearbor 38 and thegenerator 602. When the arbor rotates the armature of thegenerator 602 is rotated (via the gears 604-608) to thereby generate electricity. The electricity generated by thegenerator 602 may be used to electrically power thedetection system 30 and/or thereaction system 32. By using such agenerator 602, thedetection system 30 and/orreaction system 32 would be powered when theblade 14 is spinning. That way, thedetection system 30 and/orreaction system 32 could be powered independently of themotor 40 used to spin theblade 14. As such, thedetection system 30 and/orreaction system 32 could be powered even when themotor 40 used to rotate theblade 14 is turned off, as long as the blade/arbor is spinning. This would keep thedetection system 30 and/orreaction system 32 enabled even when the power to theblade 14 is turned off. Also, thedetection system 30 and/orreaction system 32 would not be enabled when maintenance is being performed on thesaw 10 and/orblade 14, as the blade/arbor would not be spinning in such a mode. In other embodiments, thegenerator 602 may not be geared to the arbor, but may use a drive belt or some other drive mechanism to drive thegenerator 602 when the arbor rotates. - In another embodiment, as shown in
FIG. 7 , the static electricity that accumulates on theblade 14 may be used to detect a spinning condition for theblade 14. The static electricity build-up on the blade may also be used to detect contact between theblade 14 and foreign objects. As shown in the embodiment ofFIG. 7 , a staticcharge detection circuit 702 may be coupled to, and receive as an input a signal from, theexcitation plate 34 that is capacitively coupled to theblade 14. As theblade 14 spins, static charge is generated and accumulated on theblade 14. The staticcharge detection circuit 702 may monitor the static charge on theblade 14, via theexcitation plate 34, to detect various conditions pertaining to theblade 14. For example, as theblade 14 slows down, the static charge decreases. The staticcharge detection circuit 702 may interpret the decrease in the static charge as an indication that theblade 14 is slowing down. Similarly, by monitoring the static charge on theblade 14, the staticcharge detection circuit 702 can detect when theblade 14 stops spinning. Thedetection system 30 and/orreaction system 32 may be enabled (e.g., powered on) based on the determination by the staticcharge detection circuit 702 of whether theblade 14 is still spinning. For example, the staticcharge detection circuit 702 may be in communication with a controller circuit (not shown) that outputs control signals to arm or disarm the detection and/or reaction systems based on the output from the staticcharge detection circuit 702 regarding the static charge build-up on theblade 14. In addition, as contact between theblade 14 and foreign objects (such as the material to be cut by the blade) will affect the static charge on theblade 14, the staticcharge detection circuit 702 can be used to detect contact between theblade 14 and a foreign object. Thedetection system 30 may use this information from the staticcharge detection circuit 702 to determine whether there exists a dangerous condition that warrants triggering of thereaction system 32. The staticcharge detection circuit 702 may be implemented with analog circuitry, and may also include digital circuitry in various implementations. - In another embodiment, as shown in
FIGS. 8A-B , theblade 14 may comprise one or more embedded passive electronic components orcircuits 801. Thepassive circuit components 801 may be embedded in or positioned on one or both of the sides of theblade 14. In one embodiment, theelectronic component 801 may be powered passively by incoming radio frequency signals from atransmitter 803 near theblade 14, such as embedded in thetabletop 12, under thetabletop 12, etc. The emitted signals from thetransmitter 803 may be at a relatively low power so that thepassive circuit components 801 are only passively powered when thecircuits 801 rotate past thetransmitter 803. In one embodiment, theelectronic component 801 may comprise a burst RF circuit that, when energized passively, emits a burst RF signal to areceiver 805, that may, like thetransmitter 803, be near theblade 14. The output signal from thecircuit component 801 may indicate that theRF circuit 801 is “on” due to the fact that the RF circuit is powered due to the fact that theblade 14 is spinning. Based on the signal received from theRF circuit 801, thereceiver 805 may output a signal to thedetection system 30 and/or thereaction system 32 to remain enabled. In addition, thereceiver 805 may be able to determine the speed of therotating blade 14 based on the number of burst signals received per time period (e.g., minute or second). That way, thereceiver 805 can detect whether theblade 14 is speeding up or slowing down. In other embodiments, thecircuit 801 may comprise a passively powered accelerometer or other motion sensor, with a transmitter (e.g., an RF transmitter) for transmitting sensor data to thereceiver 805. That way, based on the sensor data, thereceiver 805 may determine whether theblade 14 is spinning or not. - In another embodiment, as shown in
FIG. 9 , thesaw 10 may include avariable speed motor 901 for powering theblade 14. In such an embodiment, when thedetection system 30 detects a condition that approaches the threshold level that triggers thereaction system 32, thedetection system 30 may output a signal to thevariable speed motor 901 to reduce the speed of themotor 901, to thereby reduce the rate at which theblade 14 is spinning. That way, the motor speed may be at a reduced level if and when thereaction system 32 is triggered. In such an embodiment, therefore, thedetection system 30 may have at least two trigger levels: a first trigger level that causes the motor speed of thevariable speed motor 901 to reduce and a second trigger level that triggers thereaction system 32. The second trigger may be dropping or braking theblade 14, or some other mitigating reaction as described herein. Some time after the condition returns below the first trigger level, themotor 901 may be returned to full speed. Thedetection system 30 may be a proximity-based or contact-based detection system. An advantage of using avariable speed motor 901 is that the speed of the motor may provide feedback to the user regarding potentially dangerous conditions. For example, the reduction in motor speed may provide the user with advanced warning of a dangerous condition, and the user could react to the advanced warning, to thereby potentially avoid the mitigating reaction of thereaction system 32. - In another embodiment, as shown in
FIGS. 10A and 10B , when a dangerous condition is detected, thedetection system 30 may output a signal to change, or reverse, the direction of themotor 40. Such a mitigating reaction to a detected dangerous condition may be combined withother reaction systems 32, such as a braking reaction system (see, e.g. U.S. Pat. No. 6,920,814, which is incorporated herein by reference in its entirety), a drop mechanism (see, e.g., U.S. patent application Ser. No. 11/589,344, which is incorporated herein in its entirety), or other types of reaction systems, such as described herein. In particular, for a drop reaction system, the change in angular momentum of theblade 14 due to the change in motor direction could be leveraged to increase the rate at which theblade 14 drops beneath thetabletop 12. - As another type of reaction system, as shown in
FIG. 11 , thesaw 10 may comprise acounter-rotating flywheel 1101, which may rotate in a direction opposite the rotational direction of theblade 14. When the dangerous condition is detected by thedetection system 30, thereaction system 32 may cause a clutch 1103 to engage theflywheel 1101 with the drive for theblade 14. Preferably, theflywheel 1101 has a mass and speed such that the angular momentum of the flywheel is equal to the angular momentum of theblade 14. That way, the stored energy of theflywheel 1101 may stop theblade 14 from spinning when the clutch 1103 is engaged. If the angular momentum of theflywheel 1101 is greater than the angular momentum of theblade 14, theblade 14 may reverse direction when the clutch 1103 is engaged. In such an embodiment, a blade-braking system may be used to stop theblade 14 from reverse spinning. If the angular momentum of theflywheel 1101 is less than the angular momentum of theblade 14, theblade 14 may slow down when the clutch 1103 is engaged. Similarly, a blade-braking system may be used in such an embodiment to completely stop theblade 14 from spinning. In one embodiment, themotor 40 may power both theblade 14 and theflywheel 1101, with a transmission being used to provide the reverse rotational direction for theflywheel 1101. In another embodiment, a second motor may be used to power theflywheel 1101. Theflywheel 1101 may be located below thetabletop 12. - In another embodiment, the
blade 14 may be made out of less massive materials and/or theblade 14 may have a geometry that lessens the mass of the blade 14 (while still providing sufficient structural strength). Using a less massive blade reduces the stored energy in the blade when spinning, thus allowing the lightweight blade to be stopped or braked faster in response to the detection of a dangerous condition.FIG. 12 shows three suchexemplary blades 14 a-c. In the first embodiment, theblade 14 a comprises aninterior portion 1201 and aperipheral portion 1202. Theinterior portion 1201 may be made from a material that is less dense than theperipheral portion 1202, yet still sufficiently strong and durable. For example, theinterior portion 1201 may comprise lightweight, strong metals, such as magnesium or titanium, or composite materials. Suitable composite materials include, but are not limited to, fiber reinforced polymers, carbon-fiber reinforced plastic, glass reinforced plastic, metal matrix composites, ceramic matrix composites, organic matrix/ceramic aggregate composites, thermoplastic composite materials, or any other suitable composite material. In addition, other lightweight, strong materials could be used. Theperipheral portion 1202 of theblade 14 may comprise, for example, conventional blade materials, such as steel, and the material of theperipheral portion 1202 may be more dense than theinterior portion 1201. - In other embodiments, the blade may comprise one or more off-center holes or openings, as shown in
blades 14 b-c, to reduce the mass of the blade. The holes/openings 1207 shown in theexample blades 14 b-c are off-center in the sense that they are not the blade center-hole through which theblade 14 is mounted to its rotatable shaft. In addition, the teeth of theblades 14 a-c could comprise less massive materials, such as carbide, titanium, aluminum, composite plastics, etc. Blades of the type shown inFIG. 12 may be used in saws having an airflow-based blade-spin detection system 400 (SeeFIG. 4 ). - In embodiments using a low mass blade, such as described above, the low mass blade may be coupled to a high-
mass flywheel 1301, as shown inFIG. 13 . The high-mass flywheel 1301 may provide added momentum to theblade 14 to aid in cutting workpieces. When a dangerous condition is detected, thereaction system 32 may disengage a clutch that couples theflywheel 1301 to the blade drive. That way, thereaction system 32 can more easily stop, drop, or otherwise react the lightweight blade, and not have to additionally stop the high-mass flywheel 1301. - In another embodiment, as shown in
FIG. 14 , once a dangerous condition is detected, thereaction system 32 may cause athroat plate 1401, positioned around theblade 14 on thetabletop 12, to pop up. In such an embodiment, thethroat plate 1401 may be caused to pop up by a number of suitable actuators under thethroat plate 1401 that are actuated when the dangerous condition is detected, such as for example: pyrotechnic actuators; springs; solenoids; hydraulic actuators; pneumatic actuators; etc. By popping up, thethroat plate 1401 may create a guard around theblade 14 and/or knock foreign objects out of the vicinity of theblade 14. Thethroat plate 1401 may be made from a thin piece of metal (e.g., steel or aluminum), wood, or plastic, for example. As such, it may take less energy to cause thethroat plate 1401 to pop up than it might take to employ other types of reaction systems. In addition, the pop-upthroat plate 1401 could be combined with other reaction systems, such as braking reaction systems or blade-drop reaction systems. In addition, according to various embodiments, one side of thethroat plate 1401, such as the side at the back of theblade 14, may be pivotably connected to thetabletop 12. In such an embodiment, when the dangerous condition is detected, the other end (e.g., the front end or a side) of thethroat plate 1401 may be popped up by the actuators causing thethroat plate 1401 to rotate into theblade 14 and jam theblade 14, potentially making it stop spinning. - In another embodiment, as shown in
FIG. 15 , when a dangerous condition is detected by thedetection system 30, thetabletop 12 may pop up. Preferably, thetabletop 12 may be lifted or popped up to an elevation level that is the same as, close to, or greater than the elevation level of the top of theblade 14. That way, thetabletop 12 can remove objects from around the vicinity of the exposedblade 14. In one embodiment, thetabletop 12 may be actuated, for example, by pyrotechnic charges in response to detection of the dangerous condition by thedetection system 30, although other suitable actuation means may be used, such as pneumatic actuators, hydraulic actuators, magnetic actuators (e.g., solenoids), etc. Preferably, thetabletop 12 is moveably connected to the remainder of thebase 16 of the table saw 10 byconnectors 1501 that prevent thetabletop 12 from coming loose from the base 16 when the tabletop is elevated in response to detection of a dangerous condition. - The number of actuators will depend on, among other things, the force supplied by each actuator, their placement, and the mass/size of the
tabletop 12. In one embodiment, actuators are placed in each corner of thetabletop 12, near theconnectors 1501. In other embodiments, the actuators are located in two corners of thetabletop 12, so that thetabletop 12 effectively hinges upward when the dangerous condition is detected. The pop-uptabletop 12 could be combined with other reaction systems, such as a dropping blade. Also, the pop-uptabletop 12 preferably is combined with a guard system that prevents the workpiece from flying away when thetabletop 12 pops up. - In another embodiment, the
reaction system 32 may cause the geometry of theblade 14 to change in response to detection of a dangerous condition by thedetection system 30. As shown in the example ofFIG. 16 , theblade 14 may comprise an elongate, moveable member 1601 between eachtooth 1603 of theblade 14. The members 1601 may be connected at apivot point 1604 to theblade 14, such that the members 1601 have one free end and one fixed, or pivoting, end. In normal operating conditions, the moveable member may be in the normal or stored position, as shown bymoveable member 1601 a inFIG. 16 . In this position, themember 1601 a is tucked behind thetooth 1603 in front of it so that the moveable member 1601 does not interfere with the cutting operation. When the dangerous condition is detected, the moveable member may transition to the deployed position, as shown bymoveable member 1601 b inFIG. 16 . As can be seen inFIG. 16 , the deployedmoveable member 1601 b may pivot about thepivot point 1604 to extend in front of, and preferably beyond, the cuttingmember 1605 of thetooth 1603 when deployed. That way, the deployedmoveable member 1601 b will reduce the impact of the cuttingmember 1605 relative to the object being cut by theblade 14. - In various embodiments, the moveable members 1601 may comprise a magnetic material or a shape memory material (or alloy). For an embodiment using magnetic moveable members 1601, when the dangerous condition is detected, the
reaction system 32 may apply a magnetic field in the vicinity of theblade 14 to cause the magnetic moveable members 1601 to deploy. In an embodiment employing shape memory material moveable members 1601, thereaction system 32 may activate the shape memory moveable members 1601, such as through heat or electrical current, for example, to cause the moveable members 1601 to deploy. In other embodiments, the moveable members 1601 may have other actuating means, such as pyrotechnic charges, etc. - In another embodiment, as shown in
FIG. 17 , theblade 14 may comprise pivotingteeth members 1701. In such an embodiment, the pivotingteeth members 1701 may be connected to theblade interior 1703 at apivot 1705.FIG. 17 shows a pivotingtooth member 1701 in the open or normal position. In this position, thecutting instrument 1707 on thetooth member 1701 can cut effectively a workpiece being fed to theblade 14. When a dangerous condition is detected, the pivotingtooth member 1701 pivots forward, counter-clockwise inFIG. 17 , so that thecutting instrument 1707 is shielded completely or partially by the bladeperipheral portion 1709 in front of the pivotingtooth member 1701. In this embodiment, therefore, the pivotingtooth member 1701 rotates in the direction that theblade 14 is spinning. In other embodiments, the pivotingteeth members 1701 could be configured to pivot or rotate in the direction opposite the direction of rotation of theblade 14. - The pivoting
teeth members 1701 may be actuated by an electrical circuit, a pyrotechnic charge, or any other suitable means. In addition, in an embodiment where theblade 14 is braked, the stored rotational energy of theblade 14 may be sufficient to actuate the pivotingteeth members 1701. In any event, the pivotingteeth members 1701 preferably may be combined with another type of reaction system to mitigate the danger of thespinning blade 14, even if the teeth have retracted to a less dangerous position. For example, a blade braking system or a blade drop mechanism may also be employed. - In another embodiment, as shown in
FIG. 18 , thereaction system 32 may activate one or more visual and/or audible alarm systems when a dangerous condition is detected by thedetection system 30. For example, thereaction system 32 may be in communication, via wired and/or wireless data links, to the alarm system(s). Example alarm systems may comprise warninglight systems 1801 andaudible alarm systems 1802 that are in the building where the table saw 10 is located and/or in the table saw 10 itself. Theaudible alarm system 1802 may comprise a speaker. Thewarning light system 1801 may comprise one or more illumination devices, such as LEDs or lamps. Where wireless data links are used, the data links between thereaction system 32 and thealarm systems reaction system 32 may communicate with thealarm systems reaction system 32 may be in communication with anautomated call center 1803, which may place an automated call when the dangerous condition is detected. For example, the automated call center may place an automated call to an emergency response center (i.e., 9-1-1), relevant supervisors, or employees of the shop where thepower tool 10 is located, etc. In addition, automatic text messages, e-mails, instant messages, etc. may be placed to supervisors, etc. when the dangerous condition is detected, according to various embodiments. - In another embodiment, the
reaction system 32 may comprise anair bag 1901, as shown inFIGS. 19A-B . In one embodiment, the air bag, when it is in a non-deployed condition, may be stored in or under thethroat plate 1902 that surrounds theblade 14 on thetabletop 12. When the dangerous condition is detected, thereaction system 32 may actuate theair bag 1901, as shown inFIG. 19B . Theair bag 1901 may be inflated using, for example, a solid propellant that burns extremely rapidly to create a large volume of gas to inflate thebag 1901, much like an air bag in automobiles. In other embodiments, a canister of compressed gas may be used to inflate theair bag 1901 in response to detection of the dangerous condition. Activation of theair bag 1901 in response to detection of the dangerous condition may cause objects that are in the vicinity of theblade 14 to be knocked away from theblade 14. In addition or alternatively, an air bag could be positioned under thetabletop 12 at the side of the table saw 10 where an operator normally stands to operate the table saw 10. When activated in response to detection of the dangerous condition, such an air bag may push the operator away from thetabletop 12 and theblade 14. In addition or alternatively, the operator may wear an air bag, such as on a bracelet or belt, that is activated by thereaction system 32. In such embodiments, the wearable air bag may have a wired or wireless connection to thereaction system 32. Deployment of such a wearable air bag may knock the operator and attached extremities thereof away from thetabletop 12 and/orblade 14. - In another embodiment, as shown in
FIG. 20 , thereaction system 32 may comprise a magnetorheological (MR)rotary brake 2001 to brake theblade 14 in response to detection of a dangerous condition by thedetection system 30. TheMR rotary brake 2001, as shown inFIG. 20 , may comprise arotor 2003 fixed to theshaft 2006 that rotates the blade (not shown). Theshaft 2006 is placed in abearing 2005 and can rotate in relation to ahousing 2004 for theMR rotary brake 2001.Wires 2010 are connected, and supply electrical current, to acoil 2002. Between therotor 2003 and thehousing 2004 there may be a spacing 2007 that is filled withMR fluid 2008. TheMR fluid 2008 in the gap or spacing is physically near thecoil 2002 such that when thecoil 2002 is energized by electrical current from thewire 2010, in response to detection of a dangerous condition, the magnetic field from thecoil 2002 causes the MR fluid to greatly increase its apparent viscosity to the point of becoming a viscoelastic solid, thereby braking therotor 2003, which brakes theshaft 2006, which brakes the blade 14 (not shown) connected to theshaft 2006. That is, for example, when a dangerous condition is detected by thedetection system 30, thedetection system 30 may output a control signal to a current supply connected to thecoil 2002. In response to the control signal from thedetection system 30, the current supply may be coupled to thecoil 2002 to energize thecoil 2002. Such a MR brake reaction system could be combined, for example, with a blade drop mechanism. - In other embodiments, a MR clutch could be used to disengage the blade drive mechanism. For example, in normal operating conditions, the MR fluid in the clutch could be energized by an electromagnetic field to create a friction lock to couple the drive mechanism to the blade. When a dangerous condition is detected, the electromagnetic field is removed, causing the MR fluid to convert to its fluid state, effectively disengaging the drive mechanism from the blade.
- In various embodiments, the table saw 10 may have numerous operating modes, including “on,” “off,” and “maintenance.” An operator of the table saw 10 may transition between the modes using switches, such as one three-state switch for each of the modes, or a plurality of switches that provide similar functionality. According to various embodiments, the table saw 10 may undergo automated procedures, as shown in
FIG. 21A , when the table saw transitions to various modes. If the table saw 10 transitions to the Off mode (e.g., the operator flips the on/off switch to the off position), the table saw may take the following actions automatically: (i) theblade 14 retracts below thetabletop 12; (ii) the power to themotor 14 is cut; and (iii) thereaction system 32 is turned off. These steps may be performed in various orders, although preferably thereaction system 32 should be turned off last. If the table saw 10 transitions to the On mode, the table saw may take the following actions automatically: (i) the power to themotor 40 is turned on; (ii) thereaction system 32 is turned on; and (iii) theblade 14 is raised. Again, these steps may be performed in various orders, although preferably thereaction system 32 is turned on prior to the raising of the blade. A processor-basedcontroller 2120, as shown inFIG. 21B , may control and initiate these automatic reactions. An automated, motorized bladeheight adjustment system 2122 may be used to raise and lower the blade height in such table saws. If the table saw 10 transitions to the maintenance mode, such as if the operator hits the “maintenance” button orswitch 2124 in order to change the blade, for example, thereaction system 32 is turned off. Also, thecontroller 2120 may output a signal to themotor control circuit 2130 to turn themotor 40 on or off. Other convenience and safety features may be provided or monitored in the maintenance mode. For example, a sensor may detect whether the nut holding on the blade is over-torqued or not. Also, in the maintenance mode, the blade drive shaft may be automatically locked to aid in the blade removal process. - As an alternative to automated blade height adjustment system, side panels in the
tabletop 12 may rise automatically to surround theblade 14 when the saw is turned off. Also, the throat plate 13 (seeFIG. 1 ) could rise automatically to surround the blade when the saw is turned off. -
FIG. 22 shows an embodiment of a system that may be used to stop theblade 14 when thesaw 10 is turned off. As shown inFIG. 22 , the system may include a clutch 2201 that couples themotor 40 to theblade shaft 2202. The illustrated embodiment shows a direct drive for theblade 14, although a belt drive or gear drive could be used to power theblade 14 as well. The system also includes abrake system 2204 that, when actuated at turn off of thesaw 10, grips an interior portion of theblade 14 to stop theblade 14 from spinning, preferably in a manner that is not destructive to theblade 14. That way, when thesaw 10 is turned off, the clutch 2201 may disengage themotor 40 from theblade 14, and thebrake system 2204 may stop theblade 14 from spinning. Such an embodiment effectively eliminates the need to detect whether theblade 14 is still spinning after themotor 40 is cut in order to keep thereaction system 32 enabled because theblade 14 is braked by thebrake system 2204 immediately at turn-off. Alternatively, some of the blade spin-down detection mechanisms described herein could be used to detect blade spin down to keep thereaction system 32 active and armed, although spin down detection techniques based on themotor 40 will not be effective in such an embodiment because the power to the motor is cut. - According to various embodiments, it may be desirable to know the conductivity of the wood or other workpiece being cut by the table saw and adjust detection systems accordingly. For example, in a capacitive detection system the baseline current and/or voltage drawn from the
blade 14 during normal operations (e.g., when the blade is in contact with the workpiece, but not in contact with a foreign object) may depend on the conductivity of the workpiece. Some other types of detection systems may also utilize the conductivity of the workpiece to determine when the blade has come into contact with a foreign object. -
FIG. 23 illustrates one embodiment of atable saw 10 having aconductivity sensor 2302 for measuring the conductivity of a workpiece to be cut by theblade 14. Theconductivity sensor 2302 may provide to the detection system 30 a signal indicative of the conductivity of the workpiece being cut (or to be cut). Thedetection system 30 may comprise one or more processors for receiving and processing the signal from thesensor 2302. Thedetection system 30 may process the conductivity data from thesensor 2302 in determining whether a foreign object has come into contact with theblade 14. For example, if the workpiece has a high conductivity, its electrical behavior in contact with the blade may be closer to that of a human body part. Accordingly, thedetection system 30 may adjust its sensitivity and/or disable capacitive foreign object sensing. For example, thesaw 10 may instead use other foreign object sensing mechanisms including, for example, those discussed herein below. In addition, the detection system may provide an alert (e.g., a visual or audible alert) to the user that the workpiece has a high conductivity. - The
conductivity sensor 2302 may be physically embodied as one or more sensors that may be placed at various locations on thesaw 10. For example,FIG. 24 illustrates one embodiment of the table saw 10 with a trailingedge sensor assembly 2408. Theblade 14 of the table saw 10 is shown in contact with aworkpiece 2406, which may be moved across the table saw 10 in the direction indicated byarrow 2404. After being cut by theblade 14, theworkpiece 2406 may contact thesensor assembly 2408. Thesensor assembly 2408 may include any suitable type of sensor for measuring the conductivity of theworkpiece 2406. For example, thesensor assembly 2408 may include one or more probes made of a conductive material positioned to contact theworkpiece 2406 after it has been cut and fed past theblade 14. The probes may be used to cause a current to flow through theworkpiece 2406. The voltage drop across theworkpiece 2406 may then be used to determine its conductivity. Any suitable assembly may be used to bring the sensors into operational contact with theworkpiece 2406. For example, as illustrated inFIG. 24 , thesensor assembly 2408 may comprise awheel 2410 positioned behind theblade 14. Thewheel 2410 may be slightly narrower than the kerf of theblade 14, allowing thewheel 2410 to fit within the cut to theworkpiece 2406 made by theblade 14. Thewheel 2410 may comprise spikes (or probes) 2412 that protrude towards theworkpiece 2406. As thewheel 2410 passes through the cut in theworkpiece 2406, thespikes 2412 may come into contact with the portion of theworkpiece 2406 that has just been cut by theblade 14. Thespikes 2412 may be, or may comprise, sensor leads for measuring the conductivity of theworkpiece 2406. Sensing the conductivity of theworkpiece 2406 within a fresh cut may give a reading that is indicative of the interior of theworkpiece 2406. -
FIG. 25 illustrates another embodiment of the table saw 10 where theconductivity sensor 2302 comprises a leading edgeconductivity sensor assembly 2504 positioned at the front or leading edge of theblade 14. No workpiece is shown inFIG. 25 . In use, however, a workpiece would be moved towards the front or leading edge of theblade 14 in the direction ofarrow 2507. Thesensor assembly 2504 is illustrated upstream of theblade 14. Thesensor assembly 2504 may comprise one or morespiked wheels 2506. Thewheels 2506 may be configured to rotate about an axis parallel to thearbor 38 of theblade 14. The spikes on thewheels 2506 may come into contact with the workpiece before it contacts theblade 14. The spikes may be, or may comprise, leads for conductivity sensors for sensing the conductivity of the workpiece. In some embodiments, the spikes may be sharp, allowing them to slightly puncture the exterior of the workpiece and provide a conductivity reading from below the surface of the workpiece. According to various embodiments, one ormore wheels 2506 on the table saw 10 may be adjustable along their axis of rotation. This may allow an operator of the table saw 10 to adjust thewheels 2506 based on a width of the workpiece. -
FIG. 26 illustrates one embodiment of the table saw 10 where thesensor 2302 comprises a sensingtable top surface 2604. Thesurface 2604 may comprise a metallic or other conductive material. When thesurface 2604 is in contact with a workpiece (not shown), a current may be passed through the workpiece to measure its conductivity. According to various embodiments, an operator of the table saw 10 may place the workpiece on thesurface 2604, allowing thesaw 10 to measure the conductivity of the workpiece prior to or during a cut.FIG. 27 illustrates one embodiment of the table saw 10 where thesensor 2302 comprises asensing surface 2704 that is less than all of itstable top 2706. Thesensing surface 2704 may be positioned upstream of ablade 14 as shown inFIG. 27 , or in other embodiments it could be located at different locations of the tabletop including at a trailing edge of theblade 14. Thesensing surface 2704 may operate according to principles similar to that of thesurface 2604 described above. In use, a workpiece (not shown) may be brought into contact or proximity with the sensing surface either as the workpiece is pushed towards theblade 14 or before a cut is begun. Thissensing surface 2704 may sense the conductivity of the workpiece and adjust the operation of thedetection system 30 and/or thereaction system 32 accordingly. Thesensing surface 2704 may be electrically insulated from the rest of thetabletop 12. - According to various embodiments, the
conductivity sensor 2302 may comprise all or a portion of ablade 14 of the table saw 10. In embodiments that monitor changes in the blade capacitance to determine whether a foreign object is in contact with the blade, it may not be desirable to use theentire blade 14 to detect the conductivity of a workpiece.FIG. 28 illustrates one embodiment of asegmented blade 2802 that may be used both to detect the conductivity of a workpiece and to capacitively detect foreign objects in contact with the blade. Theblade 2802 in such embodiments may compriseconductive sensing teeth 2804 andcapacitive sensing teeth 2808 at different regions of theblade 14. Although therespective teeth FIG. 28 , it will be appreciated that they may be interspersed around theblade 2802 in any suitable pattern. Theconductive sensing teeth 2804 andcapacitive sensing teeth 2808 may be electrically insulated from one another and placed in a separate circuit paths. - In use, the
capacitive sensing teeth 2808 may be used by thedetection system 30 to determine whether a foreign object is in contact with theblade 2802. For example, thedetection system 30 may monitor a change in an electrical signal applied to thecapacitive sensing teeth 2808 due to a change in capacitance in theteeth 2808 caused by contact with a foreign object. Theconductive sensing teeth 2804 may be used as a conductivity sensor, or a portion thereof. For example, all or part of eachconductive sensing tooth 2804 may serve as a probe. An additional probe (not shown) may be otherwise placed in contact with the workpiece. For example, the operator may secure the additional probe to the workpiece. In various embodiments, the additional probe may be embedded in the saw's table top. Also, according to various embodiments, an adjacent or other nearbyconductive sensing tooth 2804 may serve as the additional probe. In use, a current may be passed from the firstconductive sensing tooth 2804, through the workpiece and through the secondconductive sensing tooth 2804. The voltage drop in the signal may be indicative of the resistance and/or conductivity of the workpiece. Because theblade 2802 may measure the conductivity of material that it is in contact with, it may be used to detect contact between the blade and a foreign object. For example, if theblade 2802 senses a large increase in the conductivity of the materials in contact with theblade 2802, it may indicate that a foreign object, such as a conductive body part, is in contact with theblade 2802. In such situations, thedetection system 30 may trigger thereaction system 32. - In the embodiment described in
FIG. 2 , theblade 14 acts as one element of a capacitor. Theexcitation plate 34 is separated from theblade 14 by a dielectric (e.g., air) and serves as a second element of the capacitor.FIGS. 29 and 30 , however, illustrate one embodiment of ablade 2900 that serves as a complete capacitor. Theblade 2900 comprises ablade body 2902, aplate 2904, and a dielectric 2906. Theblade body 2902 may comprise theteeth 2908 of theblade 2900, and may also define ahollow cavity 2910 for receiving the dielectric 2906 and theplate 2904. Within thecavity 2910, the dielectric 2906 may be positioned between theblade body 2902 and theplate 2904 and may cause electrical insulation of thebody 2902 andplate 2904. In this way, theblade body 2902 andplate 2904 may serve as elements of a capacitor. When theblade 2900 is used in a detection system, such as thedetection system 30 described above, theexcitation plate 34 may be omitted. Instead, the excitation voltage may be driven onto theblade body 2902 via thecapacitor plate 2904. Thecapacitor plate 2904 may be connected to a voltage drive source via a connection through the blade shaft that is insulated from the shaft and theblade body 2902. Because theblade 10 itself makes up the entire capacitor, its capacitance may be more easily set during manufacture. In contrast, the capacitance of theblade 14 andexcitation plate 34 capacitor described above is dependent on various unpredictable environmental conditions, and therefore, its capacitance at any given time may be difficult to control or adjust. For example, the dielectric 2906 may be selected to achieve a desirable blade capacitance. Also, the surface area of thebody 2902 and theplate 2904 may be manipulated. Manipulating the blade capacitance may lead to superior detection performance as well as an improved signal-to-noise ratio. -
FIG. 31 illustrates one embodiment of ablade 3100 comprising a plurality ofblade whiskers 3102 radiating generally from the center of theblade 3100. Theblade 3100 may be used with any saw having a detection system, such as the saw described inFIG. 2 above. Theblade whiskers 3102 may extend radially from theblade 3100, creating a contact radius beyond theteeth 3104. In one example embodiment, thewhiskers 3102 may extend up to about 1 mm beyond theteeth 3104. In this way, a foreign object contacting theblade 3100 may contact thewhiskers 3102 before contacting theteeth 3104. Thewhiskers 3102 may be short enough to avoid wrapping around a foreign object, such as the finger of an operator, and thus pulling it into theblade 3100. According to various embodiments, thewhiskers 3102 may be electrically conductive and electrically coupled to all or a portion of theblade 3100. When the foreign object contacts thewhiskers 3102, the capacitance, and thus the signal drawn from theblade 3100, may begin to change. Because this change begins to occur before the foreign object contacts theteeth 3104 of theblade 3100, the effective reaction type of the saw may be improved. According to various embodiments, the length of thewhiskers 3102 may be selected based on the reaction type of the detection and reaction systems of thesaw 10. For example, if the typical reaction time of thesaw 10 without thewhiskers 3102 results in a cut 0.6 mm in depth, then the whiskers may be 0.6 mm or longer to prevent any cut in the event of a foreign object contacting the blade. - When the
blade 3100 is used to cut a workpiece, thewhiskers 3102 may be designed to bend or retract out of the path of theteeth 3104. In this way, theteeth 3104 may cut the workpiece without interference from thewhiskers 3102. Thewhiskers 3102 may be made, for example, from a metal wire (e.g., steel, aluminum, etc.). Also, for example, thewhiskers 3102 may be made from a conductive carbon composite or other electrically conductive material. According to various embodiments, thewhiskers 3102 may comprise a non-capacitive sensor. For example, eachwhisker 3102 may comprise one or more probes for measuring the conductivity of materials in contact with theblade 3100. Also, according to various embodiments, theblade 3100 may include a mechanism for replenishing the length of thewhiskers 3102. In use,individual whiskers 3102 may be broken or torn as they contact the workpiece. Accordingly, one or more of thewhiskers 3102 may comprise a reel (not shown) of additional whisker material. The reel may be actuated by centripetal force to extend additional whisker material when itscorresponding whisker 3102 is lost or shortened. -
FIG. 32 illustrates a diagram of one embodiment of asegmented blade 3200 that may be used with the saw embodiment shown inFIG. 2 . Theblade 3200 is shown in the process of cutting aworkpiece 3210.Arrow 3212 indicates the direction of movement of theworkpiece 3210 relative to theblade 3200.Arrow 3214 indicates the rotation direction of theblade 3200. InFIG. 32 , theblade 3200 is shown with four electrically insulatedsegments segments excitation plate 34 and/or utilizing a laminate design such as described above with respect toFIGS. 29 and 30 ). Because the segments are electrically insulated, each capacitor (e.g., eachblade segment detection system 30. - As the blade spins, each of the
segments FIG. 32 , segment 3204), a trailing portion of the workpiece 3210 (inFIG. 32 , segment 3202) and no portion of the workpiece (inFIG. 32 ,segments 3206 and 3208). The capacitance of each segment (e.g., as measured by an excitation current and/or voltage) may reflect the properties of the material in contact with the respective segment. This may enable a variety of useful features. For example, thesegmented blade 3200 may enable thedetection system 30 to re-calibrate on-the-fly. Portions of the blade cycle where a givensegment workpiece 3210 may be used as baseline measurements for recalibration of the segment. Also, for example, thedetection system 30 may be able to track whether the saw is at the beginning, middle, or end of a cut. This may allow thedetection system 30 to calibrate its sensitivity accordingly. Also, use of theblade 3200 may allow the detection system to compare differences in properties between the leading portion and the trailing portion of theworkpiece 3210. -
FIG. 33 illustrates one embodiment of the table saw 10 having anoverhead sensor assembly 3304. Theoverhead sensor assembly 3304 may comprise one or more sensors, which may be active or passive. For example, an active sensor may comprise an emitter as well as a receiver. Sensors that are passive may not comprise an emitter. According to various embodiments, the transmitter and receiver may be separate, with one or both of them located on thesaw 10 at a location different from theoverhead sensor assembly 3304. When thesaw 10 is in use, itsblade 3302 and aworkpiece 3308 may be in the field of view of at least one of the sensors of thesensor assembly 3304. - According to various embodiments, the
sensor assembly 3304 may comprise a radar sensor. A radar sensor may comprise an emitter that generates electromagnetic waves (e.g., radio waves, microwaves, etc.) and directs the electromagnetic waves toward theblade 3302. The waves may reflect off of theblade 3302, theworkpiece 3308 and any foreign objects that may be present. A receiver may sense the reflected waves and provide an output signal to a processor-baseddetection system 30. Thedetection system 30 may glean various information from the input signal about the reflected waves. For example, the reflected waves may provide an indication of the direction and speed with which theworkpiece 3308 is moving relative to the blade. If theworkpiece 3308 reverses its motion, that may indicate a kickback event, which may cause thedetection system 30 to activate thereaction system 32. If a foreign object is detected within a predetermined distance from theblade 3302, then areaction system 32 may be activated. For example, if a foreign object is detected between theblade 3302 and thesensor assembly 3304, thereaction system 32 may be activated by thedetection system 30. More details regarding a radar sensing system may be found in U.S. Pat. No. 7,421,932, which is incorporated herein by reference in its entirety. - According to various embodiments, the
sensor assembly 3304 may comprise an infrared (IR) receiver. The IR receiver may sense the IR signature of theblade 3302, theworkpiece 3308, and any foreign objects present in its field-of-view. The IR signature of theblade 3302 andworkpiece 3308 may be distinguishable from the IR signature of a body part or other foreign object that may inadvertently come near the blade. Thedetection system 30 may monitor the output of the IR receiver. If the IR receiver indicates that a foreign object is within a predetermined distance from theblade 3302, a reaction system may be activated. For example, if a foreign object is detected between theblade 3302 and thesensor assembly 3304, thereaction system 32 may be activated. - In other embodiments, the
sensor assembly 3304 may include emitters and receivers for measuring backscatter off of theblade 3302, theworkpiece 3308 and any foreign objects that may be present near-by. Any suitable frequency of electromagnetic radiation may be used to measure backscatter. According to various embodiments, however, a frequency or frequencies may be selected based on the difference in backscatter profiles betweentypical workpieces 3308 and typical foreign objects, such as human body parts. In use, backscatter techniques may be able to differentiate betweenworkpieces 3308 and foreign objects. For example, a foreign object, such as the skin on a body part, may scatter back a first quantity of radiation, while aworkpiece 3308 of the same surface area may scatter back a second quantity of radiation. This may allow thedetection system 30 to differentiate between the two. If a foreign object is detected within a predetermined distance of the blade 3302 (e.g., if the foreign object is over theblade 3302 or between theblade 3302 and the sensor assembly 3304), then thereaction system 32 may be activated by thedetection system 30, which is in communication with thesensor assembly 3304. - In some embodiments, the
sensor assembly 3304 may include an optical camera (e.g., a CCD camera). The optical camera may have a resolution fine enough to allow it to determine a distance between a foreign object and theblade 3302. If the distance is less than a predetermined amount, thereaction system 32 may be triggered by thedetection system 30. Various image processing algorithms may be used by thedetection system 30 to distinguish the blade, a typical workpiece, and a foreign object. - In various embodiments, the
sensor assembly 3304 may include an emitter and receiver for measuring differential reflection. Differential reflection may be a measure of difference in reflection between surfaces. For example, a foreign object may reflect more or less electromagnetic radiation as compared to atypical workpiece 3308 and/or theblade 3302. The emitter for differential reflection may be any suitable emitter of electromagnetic waves including, for example, a laser. Thedetection system 30 is in communication with thesensor assembly 3304 and determines whether thereaction system 32 should be triggered based on the differential reflection detected by thesensor assembly 3304. -
FIGS. 34-42 illustrate embodiments utilizing downstream safety members (e.g., safety members that are positioned near the trailing or rear edge of the blade 14). A downstream safety member is a component of a table saw that is positioned parallel to and downstream from theblade 14. Specific examples of downstream safety members include riving knives and splitters. Different downstream safety members may serve different purposes, for example, as described herein. Generally, a downstream safety member may serve to steady a workpiece and/or to mitigate the risk of a kickback event by preventing a cut from closing around theblade 14. -
FIG. 34 illustrates one embodiment of adownstream safety member 3400 havingdirectional snells 3402. Thesnells 3402 may extend outwardly at an angle from thedownstream safety member 3400. Thesnells 3402 may be configured so that a workpiece may smoothly pass over thesnells 3402 in the downstream direction, but is impeded if the workpiece is kicked-back in the upstream direction.FIG. 35 illustrates a top view of thedownstream safety member 3400. Aworkpiece 3406 is illustrated being pushed downstream, as indicated byarrow 3408. When theworkpiece 3406 contacts thesnells 3402 moving downstream, it may slide along thesnells 3402 without significant resistance because the snells are pointed generally away from the blade and in the direction that the workpiece is being fed. In the event of a kickback, however, theworkpiece 3406 may be thrust upstream. In this case, thesnells 3402 may dig into theworkpiece 3406, either preventing the workpiece from moving upstream or impeding its upstream motion. - The
snells 3402 may take any suitable form and may be made of any suitable material (e.g., steel, another suitable metal, engineered plastic, etc.). For example, in various embodiments, thesnells 3402 may be flexible flaps formed into or secured to thedownstream safety member 3400. When theworkpiece 3406 passes in the downstream direction, the flaps may flex, allowing theworkpiece 3406 to pass. When the workpiece is thrust upstream, the flaps may not flex and may instead dig into theworkpiece 3406, impeding its upstream movement. According to various embodiments, thesnells 3402 may be actuatable by thereaction system 32. For example, eachsnell 3402 may be extendible from a rest position, where theworkpiece 3406 is allowed to pass without significant resistance, to an extended position, where the motion of theworkpiece 3406 is impeded. When a kickback condition is detected, thereaction system 32 may extend thesnells 3402 to prevent theworkpiece 3406 from being thrust back towards the operator and/or theblade 14. Thesnells 3402 may be actuated according to any suitable mechanism. For example, a mass of nitinol or another shape memory allow may be actuated to lift eachsnell 3402 to the extended position. In other embodiments, eachsnell 3402 may be spring loaded from the rest position to the extended position. In still other embodiments, thesnells 3402 may be extended using solenoids, pneumatics, hydraulics, magnets, pyrotechnics, or any other suitable method. -
FIGS. 36-38 illustrate one embodiment of the table saw 10 including adownstream safety member 3602 comprising one ormore wing members 3604. Thewing members 3604 may extend roughly parallel to thetable surface 3614 and roughly perpendicular to abody 3608 of thedownstream safety member 3602. Aworkpiece 3610 being acted upon by ablade 14 may pass under thewing members 3604 when extended. In this way, thewing members 3604 may serve to prevent theworkpiece 3610 from lifting off of the table surface. This may prevent and/or mitigate a kickback event. During a typical kickback event, the motion of theworkpiece 3610 relative to theblade 14 is stopped or slowed (e.g., when theblade 14 contacts a knot or hard portion of theworkpiece 3610, by a pinching off of the cut behind theblade 14, etc.). When theworkpiece 3610 is stopped or slowed, the motion of theblade 14 pushes theworkpiece 3610 up, where it contacts the top of theblade 14 and is thrust back towards the operator.Wing members 3604 may prevent or mitigate a kickback event by preventing theworkpiece 3610 from riding upwards relative to theblade 14. - According to various embodiments, the
wing members 3604 may be movable from a resting position to a deployed position when triggered, such as by turn-on of the motor/blade. In the resting position, thewing members 3604 may be parallel to abody 3608 of thedownstream safety member 3602. In some embodiments, the combined width of thebody 3608 and the wing member ormembers 3604 may be less than the kerf of theblade 14, allowing thedownstream safety member 3602 to pass through the cut in the workpiece formed by theblade 14 if thewing members 3604 are in the resting position. Normally, thewing members 3604 are deployed when the saw is being operated.FIGS. 36 and 37 illustrate one embodiment where thewing members 3604 fold down against thebody 3608 of thedownstream safety member 3602 when in the resting position.FIG. 38 illustrates another embodiment where thewing members 3604 fold upwards when in the resting position. In such an embodiment, thewing members 3604 may transition to the deployed position, parallel to the tabletop when triggered by a kickback detection system. According to various embodiments thedownstream safety member 3602 may comprise aheight adjustment mechanism 3616 for raising and lowering thedownstream safety member 3602. This may allow an operator to adjust the height of thewing members 3604 based on the height of theworkpiece 3610. - According to various embodiments, the
downstream safety member 3602 may be actuated from the resting position to the deployed position by thereaction system 32 upon detection of a kickback event by thedetection system 30. The kickback event may be sensed according to any suitable method including, for example, those described herein below. Upon detection of the kickback event, thereaction system 32 may cause thewing members 3604 to be transitioned, such as from the upright resting position shown inFIG. 38 , to the deployed position using any suitable mechanism or method. For example, thewing elements 3604 may be actuated by a spring element, solenoids, pneumatics, hydraulics, pyrotechnics, etc. - According to various embodiments, a downstream safety member can be used as a component of the
reaction system 30. For example, the downstream safety member may be used to cover the exposed portion of theblade 14 or otherwise prevent or stop contact between theblade 14 and a foreign object.FIGS. 39 and 40 illustrate one embodiment of the table saw having adownstream safety member 3904. Thedownstream safety member 3904 has a resting position, shown inFIG. 39 , and a deployed position, shown inFIG. 40 . In the resting position, a portion of thedownstream safety member 3904 may extend above thetable top 3906 and serve as a standard downstream safety member, such as a splitter. - The
detection system 30 may detect a dangerous condition according to techniques described herein, including contact between theblade 14 and a foreign object or proximity of the foreign object to the exposed portion of theblade 14. When the condition is detected, thedetection system 30 may trigger thereaction system 32. Thereaction system 32 may, in turn, trigger anactuating mechanism 3910, which may rapidly transition thedownstream safety member 3904 from the resting position, shown inFIG. 39 , to the deployed position, shown inFIG. 40 . In this way, thesafety member 3904 may prevent the foreign object from contacting theblade 14, or if the foreign object has already contacted theblade 14, thesafety member 3904 may push or knock the foreign object away from theblade 14. - The
downstream safety member 3904 may be transitioned from the resting position to the deployed position according to any suitable actuation mechanism or method. In some embodiments, the saw may include tracks (not shown) for directing thedownstream safety member 3904 from the resting position to the deployed position. Theactuating mechanism 3910 may comprise any suitable mechanism for moving thesafety member 3904 along the tracks including, for example, spring loading, pneumatics, hydraulics, explosive charges, etc. Also, in some embodiments, thedownstream safety member 3904 may be directed from the resting position to the deployed position by a series of pivotable bar members (not shown). In these embodiments, theactuating mechanism 3910 may be configured to pivot thedownstream safety member 3904 about the bars again using any suitable mechanism (e.g., spring loading, pneumatics, hydraulics, pyrotechnics, etc.). -
FIG. 41 illustrates another embodiment of thesaw 10 having adownstream safety member 3952 that may be used as part of areaction system 32. Upon detection of a triggering condition involving a foreign object and theblade 14 by thedetection system 30, thedownstream safety member 3952 may be split into two or more sections. Theactuating mechanism 3910 may propel a first section alongtrack 3958, and a second section alongtrack 3956. As shown inFIG. 41 , the tracks may run generally parallel to theblade 14 on opposite sides of theblade 14. In this way, thedownstream safety member 3952 may cover theblade 14 to prevent and/or mitigate contact between theblade 14 and a foreign object. In some embodiments, thedownstream safety member 3952 may not split in two, but instead the entiredownstream safety member 3952 may be propelled down a track on one side of theblade 14. Theactuating mechanism 3910 may utilize any suitable propelling mechanism including, for example, spring loading, pyrotechnics, solenoids, pneumatics, hydraulics, etc. -
FIG. 42 illustrates one embodiment of asaw 10 having adownstream safety member 4202 with a material sensor 4204 thereon. The material sensor 4204 may be any suitable type of sensor for sensing a property of a workpiece (not shown). For example, the sensor 4204 may be a conductivity sensor for sensing the conductivity of the workpiece which, as described above, may be an indicator of its moisture content. The sensor 4204 may be positioned at any suitable location on thedownstream safety member 4202, and may take any suitable physical form. For example, the sensor 4204 may include probes that extend perpendicularly from thedownstream safety member 4202 to contact material within a cut on a workpiece created by theblade 14. The sensor 4204 may be in communication with thedetection system 30 in a manner similar to that described above with respect toFIG. 23 . - In some table saws, the blade height is manually adjustable, such as by using a crank. An operator of the table saw may adjust the blade height to match the height of the workpiece being cut. Many operators, however, neglect to adjust the blade height for each cut. Instead, operators sometimes set the blade to a height that is high enough to allow them to cut a number of workpieces. As a result, the blade is sometimes too high for certain cuts, creating a potentially unsafe condition.
FIG. 43 illustrates a block diagram of a table saw 4300 with an automaticallyadjustable blade 14. Theblade 14 may be adjustable with amechanical adjustment mechanism 4320. Themechanism 4320 may be any suitable type of mechanism including, for example, known manual blade height adjustment mechanisms. Themechanism 4320 may be powered by anactuating mechanism 4321, such as a stepper motor or other suitable device. Aheight sensor 4324 may be used to sense the height of the workpiece currently being cut by theblade 14. Thesensor 4324 may be any suitable type of sensor including, for example, an optical sensor. Thesensor 4324 may be positioned so that it can measure the height of workpieces at a location in front of the leading edge of theblade 14. Theheight sensor 4324 may provide an output signal indication of the height of the workpiece to a processor-basedheight adjustment circuit 4322. From the output signal of thesensor 4324, thecircuit 4322 may determine the height of the workpiece and whether the blade height needs to be adjusted or not given the height of the workpiece. Thecircuit 4322 may then signal theactuating mechanism 4321 to adjust themechanism 4320 to raise or lower theblade 14 based on the height of the workpiece. For example, theblade 14 may be raised such that its top is a predetermined distance above the top of the workpiece. In some embodiments, the bladeheight adjustment mechanism 4320 may also raise or lower themotor 40 as well. -
FIGS. 44-46 illustrate one embodiment of the table saw 10 according to other embodiments. Theblade 14 andtable top surface 4304 are shown inFIGS. 44-46 . Theheight sensor 4324 may comprise afan emitter 4308 and a detector array 4306 (shown inFIG. 44 ). Thefan emitter 4308 may emit a laser or other electromagnetic beam across thetable top 4304 andworkpiece 4307 towards thedetector array 4306. The beam may be ‘fanned’ or shaped to disperse vertically. When theworkpiece 4307 breaks the beam, a portion of the beam may be prevented from reaching thesensor array 4306. Based on the portion of the beam that reaches thedetector array 4306, theheight adjustment circuit 4322 may determine the height of the workpiece and send appropriate signals/instructions to theactuating mechanism 4321.FIGS. 45 and 46 illustrate the operation of thesaw 10 with two workpieces, 4307′ and 4307″. As shown inFIG. 45 , theworkpiece 4307′ has a first height. InFIG. 45 , theblade 14 is shown relative to thetable top 4304 at a height roughly corresponding to that of theworkpiece 4307′. As shown inFIG. 46 , theworkpiece 4307″ has a second height that is greater than that of theworkpiece 4307′. Accordingly,FIG. 46 shows theblade 14 at a greater height relative to the tabletop than is shown inFIG. 45 . The height of theblade 14 relative to the tabletop inFIG. 46 may roughly correspond to the height of theworkpiece 4307″. - Various embodiments of the present invention are also directed to retrofitting existing table saws with detection and reaction systems.
FIG. 47 illustrates one embodiment of thesaw 10 with aretrofit package 4702 installed. Theretrofit package 4702 may comprise adetection system 30, areaction system 32 and apower system 4704. Thedetection system 30 may be any suitable type of detection system including, for example, those described herein. For example, in one embodiment, theretrofit package 4702 may comprise anexcitation plate 34 that is installed next to theblade 14, as shown. Thedetection system 30 may drive a signal onto the excitation plate and monitor changes in the resulting blade current or signal due to changes in the capacitance between theblade 14 and theplate 34 to detect contact between theblade 14 and a foreign object. In some embodiments, theblade 14 may be replaced with a blade that does not require an excitation plate such as, for example,blade 2900 described herein. Othernon-capacitive detection systems 30 may be used including, for example, the radar, backscatter, and/or video-based embodiments described herein. - The
reaction system 32 may comprise any suitable type of reaction mechanism. According to various embodiments, however,reaction systems 32 requiring a minimum of modification to thesaw 10 may be selected. Examples of such systems include those utilizing actuatable throat plates, actuatable table tops, airbags, changes to the blade shape, blade brakes, etc. Thereaction system 32 anddetection systems 30 of theretrofit package 4702 may be powered by apower system 4704. Thepower system 4704 may comprise a connection to a power source of thesaw 10. According to various embodiments, thepower system 4704 may comprise a blade-driven generator, such as those described with reference toFIGS. 5-6 . In this way, the reaction anddetection systems blade 14 completely spins down. - Operators of table saws sometimes use push sticks to guide or feed the workpieces towards the blade. Use of a push stick may allow the operator to keep their hands farther away from the
blade 14 when feeding a workpiece toward theblade 14.FIGS. 48 and 49 illustrate one embodiment of apush stick 4802 according to various embodiments of the present invention. Thepush stick 4802 may comprise a handle and an end effector, separated by a shaft. The operator may grasp thepush stick 4802 by the handle and use the end effector to push the workpiece, as shown inFIG. 49 .FIG. 50 illustrates a block diagram of thepush stick 4802 in communication with anexample saw 4820. According to various embodiments, thepush stick 4802 may comprise one ormore accelerometers 4810. The accelerometer(s) 4810 may be in communication with atransmitter 4824, which may transmit signals indicative of the acceleration of thepush stick 4802 to the saw 4820 (e.g., via receiver/detector 4822). Thedetection system 30 of thesaw 4820 may monitor the acceleration of thepush stick 4802, as this may be indicative of the acceleration of theworkpiece 4804 and/or the operator's hand. If the acceleration of thepush stick 4802 falls outside of acceptable bounds, thedetection system 30 may trigger thereaction system 32. For example, the acceleration of the push stick may be outside of acceptable bounds if the stick accelerates too quickly in the direction of theblade 14. In addition, a sudden acceleration away from theblade 14 may indicate a kick back condition. Thepush stick 4802 may also comprise devices and/or sensors allowing thedetection system 30 to estimate its location. For example, thepush stick 4802 may comprise a Radio Frequency (RF)transmitter 4812 that may periodically transmit RF pulses. The saw 4820 (e.g., via the detector/receiver 4822) may receive the RF pulses. Based on the strength of the RF pulses, thedetection system 30 may estimate the distance between thepush stick 4802 and theblade 14. In some embodiments, thepush stick 4802 may comprise an infrared (IR) pulse generator. The IR pulses may be received by thesaw 4820. For example, thesaw 4820 may comprise a plurality of IR receivers positioned at different locations on thesaw 4820. These may allow the saw to use triangulation to estimate the position of thepush stick 4802 relative to the blade, for example. -
FIG. 51 is a top view of atable saw 10 with asuction feed assembly 5102 for feeding workpieces towards theblade 14 according to various embodiments of the present invention. The suction feed assembly may comprise a plurality ofsuction elements 5104 located on the table at the leading edge of theblade 14. Eachsuction element 5104 may comprise one or more suction generated devices. When actuated, the suction generating devices may create a vacuum between thesection element 5104 and any object in contact with the section element 5104 (e.g., the workpiece). Eachsuction element 5104 may reciprocate towards and away from the blade, for example, as shown byarrows 5106.Adjacent section elements 5104 may reciprocate 180° out of phase. Accordingly, thesuction elements 5104 may be selectively actuated and de-actuated to move a workpiece towards or away from theblade 14. In this way, it may not be necessary for an operator to place their hand near theblade 14. Instead, thesuction elements 5104 may feed the workpiece toward theblade 14. The state of the feedback from thesuction elements 5104 can be used to detect hazardous conditions. -
FIG. 52 illustrates a top-down view of one embodiment of a kick backdetection mechanism 5200. As shown in the illustrated embodiment, theblade 14 andarbor 38 may be mounted in a kick backframe 5202 that is pivotable relative to the remainder of the table saw about the joint 5204.Arrow 5208 indicates the direction of movement of a workpiece. The kick backmechanism 5200 may serve a variety of purposes. For example, many kickback conditions occur when a cut is pinched or otherwise knocked out of alignment, causing the cut portion of a workpiece to contact a rear portion of theblade 14. Because the kick backmechanism 5200 allows theblade 14 some freedom of motion around thepivot 5204, it may prevent many kickback conditions. In some embodiments, the kick backmechanism 5200 may comprise a sensor (not shown) positioned to sense movement of the kick backframe 5202 about the joint 5204. The sensor may be in communication with thedetection system 30. Movement of the kick backframe 5202 about the joint 5204 may indicate a kickback condition. Accordingly, when thedetection system 30 receives a signal from the sensor indicating that greater than a predetermined amount of motion has occurred about the joint 5204, it may trigger areaction system 32.FIG. 53 illustrates an alternative embodiment of the kick backmechanism 5200′. With themechanism 5200′, theblade 14 andarbor 38 are mounted to a four-bar linkage frame 5210, which is shown rigidly mounted to aportion 5214 of the saw. The four-bar linkage frame 5210 may allow theblade 14 to move from side-to-side, as illustrated byarrow 5216. This may serve to prevent kickback conditions, as described above. Also, for example, a sensor may be positioned to sense movement of thelinkage frame 5210, which, if greater than a predetermined threshold, may indicate a kickback condition. The sensor (not shown) may be positioned at any location allowing it to sense movement of theframe 5210, but may be positioned at one of thejoints 5212 of theframe 5210. In another embodiment, strain measurements, from a strain sensor, on thekickback frame 5202 can be used to detect a kickback condition, without having to use a pivot. -
FIG. 54 illustrates one embodiment of thesaw 10 having torque-based kick back detection mechanism. When a kickback event occurs, the workpiece may come into contact with a trailing or rear portion of theblade 14. This may increase the torque that themotor 40 must produce to maintain a constant rotation of theblade 14. Accordingly, in such embodiments, thesaw 10 comprises one or more torque sensors 5402 mounted on a shaft between themotor 40 and theblade 14. For example, the torque sensor 5402 may be mounted on the arbor shaft to which theblade 14 is secured, or some other drive shaft between themotor 40 and theblade 14. Thedetection system 30 may be in communication with the torque sensor(s) 5402. If the torque sensor(s) 5402 indicates that the torque on the shaft has increased by more than a predetermined amount, it may indicate that a kickback condition has occurred. Accordingly, thedetection system 30 may trigger the mitigating reaction of thereaction system 32. Any suitable torque sensor 5402 may be used, such as strain gauge torque sensors or surface acoustic wave (SAW) torque sensors. - According to various embodiments, embodiments of the present invention are directed to a table saw that comprises: a cutting surface; a motor-driven, rotatable blade for cutting a workpiece on the cutting surface, wherein a portion of the blade is extendable above the cutting surface; a kickback detection system for detecting kickback of the workpiece during cutting of the workpiece; and reaction means in communication with the kickback detection system for taking a mitigating reaction in response to detection of kickback of the workpiece during cutting of the workpiece. According to various implementations, the kickback detection system comprises: an acoustic sensor; and a processor in communication with the acoustic sensor, wherein the processor is programmed to recognize a condition indicative of kickback of the workpiece during cutting of the workpiece based on input from the acoustic sensor. The processor may be further programmed to determine whether the blade is rotating based on input from the acoustic sensor, and, when it is determined that the blade is rotating, maintain the reaction means in an armed state. In addition, the kickback detection system may comprise: a torque sensor mounted on the rotatable blade shaft; and a processor in communication with the torque sensor, wherein the processor is programmed to recognize a condition indicative of kickback of the workpiece during cutting of the workpiece based on input from the torque sensor. In other embodiments, the table saw further comprises: a motor positioned below the cutting surface; a rotatable blade shaft positioned below the cutting surface on which the blade is mounted; a clutch coupled to the blade shaft, such that when the clutch is engaged and the motor is running, the blade shaft is rotated; a brake system for braking the blade; and a motor shut-down circuit connected to the clutch and the brake system, wherein the motor shut-down circuit disengages the clutch and actuates the brake system to brake the blade when the motor is turned off.
- According to other embodiments, the table saw comprises: a cutting surface; a motor-driven, rotatable blade for cutting a workpiece on the cutting surface, wherein a portion of the blade is extendable above the cutting surface; detection means for detecting a dangerous condition relative to the blade; reaction means in communication with the detection means for taking a reaction in response to detection of the dangerous condition; and a blade-spin detection system for detecting whether the blade is rotating based on energy from the blade, wherein the blade-spin detection system is in communication with the reaction means and provides an output to arm the reaction means when the blade-spin detection system detects that the blade is spinning. In various implementations, the blade-spin detection system comprises a static electricity charge sensor in proximity to the blade for sensing the static electricity build-up on the blade. In other implementations, the blade-spin detection system comprises: a transmitter proximate to the blade for transmitting radio signals; a passive electronic circuit on the blade that transmits responsive radio signals when passively energized by the radio signals transmitted by the transmitter; and a receiver, proximate to the blade, for detecting the responsive radio signals from the passive electronic circuit. In yet other implementations, the blade-spin detection system comprises: an acoustic sensor; and a processor in communication with the acoustic sensor, wherein the processor is programmed to determine whether the blade is rotating based on input from the acoustic sensor. In yet other implementations, the blade-spin detection system comprises: an airflow sensor that senses airflow generated by the plurality of off-center holes of the blade when the blade spins; and a processor in communication with the airflow sensor, wherein the processor is programmed to determine whether the blade is rotating based on input from the acoustic sensor. In yet other implementations, the blade-spin detection system comprises: one or more magnets mounted on the blade; and an inductor proximate to the blade, wherein the magnets, when spinning with the blade, induce a voltage across the inductor, wherein the reaction means is connected to the inductor. In addition, the table saw may further comprise a power converter having an input connected to the inductor for converting the voltage across the inductor to an output voltage used to power the reaction means and/or the detection means.
- According to various implementations, the blade comprises a plurality of off-center holes that extend through the blade. In addition, the table saw may further comprise an electrical generator connected by one or more gears to the rotatable blade shaft, wherein the electrical generator is further connected to the reaction means and generates electricity when the shaft rotates to power the reaction means and/or the detection means. In addition, the reaction means may comprise: a clutch coupled to the blade shaft, such that when the clutch is engaged and the motor is running, the blade shaft is rotated, and wherein the clutch is disengaged when the detection means detects the dangerous condition; and a brake system for braking the blade when the detection means detects the dangerous condition. Additionally, the blade may comprise an outer peripheral portion that comprises a first material, an inner portion that comprises a second material that is different from the first material, wherein the first material is denser than the second material. In addition, the table saw may further comprise: a flywheel that rotates in a direction that is the same as a direction of rotation for the blade, wherein the flywheel is coupled to the rotatable shaft by a clutch, and wherein the reaction means disengages the clutch when the dangerous condition is detected. In addition, the table saw may further comprise kickback mitigation means downstream from the blade for mitigating kickback of the workpiece and/or a suction feed assembly that feeds the workpiece to the blade for cutting.
- According to other embodiments, the table saw comprises: a cutting surface; a motor-driven, rotatable blade that is partially extendable above the cutting surface for cutting a workpiece positioned on the cutting surface; and a sensor connected to the cutting surface for sensing a characteristic of the workpiece during cutting of the workpiece. In various implementations, the table saw further comprises a blade height adjustment mechanism for adjusting a height of the blade relative to the cutting surface, the sensor comprises a height sensor for sensing a height of the workpiece relative to the cutting surface, and the table saw further comprises a height adjustment circuit that receives an input signal from the height sensor indicative of the height of the workpiece relative to the cutting surface and outputs a signal to the blade height adjustment mechanism to adjust the height of the blade based on the height of the workpiece sensed by the height sensor. In other implementations, the sensor comprises a workpiece conductivity sensor on the cutting surface that detects electrical conductivity of the workpiece. In such an implementation, the table saw may further comprise: contact detection means for detecting contact with the blade by an object other than the workpiece, wherein the contact detection means receives an input from the workpiece conductivity sensor and detects contact with the blade by the object based on the input from the workpiece conductivity sensor; and reaction means in communication with the contact detection system for taking a mitigating reaction in response to detection of contact with the blade by the object. The workpiece conductivity sensor may comprise a wheel positioned adjacent to a trailing and/or leading edge of the blade, wherein the wheel comprises one or more probes that extend into the workpiece to sense the electrical conductivity of a portion of the workpiece after cutting of the portion by the blade.
- According to other embodiments, the table saw comprises: a cutting surface; a motor-driven, rotatable blade for cutting a workpiece on the cutting surface, wherein a portion of the blade is extendable above the cutting surface; a contact detection system for detecting contact with the blade by an object other than the workpiece; and reaction means in communication with the contact detection system for taking a mitigating reaction in response to detection of contact with the blade by the object. The blade comprises: a first electrically conductive blade portion; a second electrically conductive blade portion; and a dielectric between the first and second electrically conductive blade portions. The contact detection system is connected to the first electrically conductive blade portion and drives the first electrically conductive blade portion with a drive signal, and wherein the contact detection system comprises a processor for detecting contact with the blade by the object based on an electrical signal from the first electrically conductive blade portion. For example, the contact detection system may detect contact with the blade by a foreign object based on the current drawn by the first electrically conductive blade portion.
- According to other embodiments, the table saw comprises: a cutting surface; a motor-driven rotatable shaft positioned below the cutting surface; a blade for cutting a workpiece on the cutting surface, wherein the blade is mounted on the shaft, and wherein a portion of the blade is extendable above the cutting surface; a detection system for detecting a dangerous condition relative to the blade; a reaction system in communication with the detection system for taking a reaction in response to detection of the dangerous condition, wherein the reaction system comprises a magnetorheological rotary brake connected to the shaft that brakes the shaft to thereby brake the blade in response to detection of the dangerous condition by the detection system. In various implementations, the magnetorheological rotary brake comprises: a rotor fixed to the shaft; a housing, wherein the housing and the rotor define a spacing; magnetorheological fluid in the spacing; and a magnetic field-producing coil that is energized in response to detection of the dangerous condition by the detection system to produce a magnetic field that causes the magnetorheological fluid to increase its viscosity to brake the rotor, thereby braking the shaft, thereby braking the blade.
- While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions, and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims.
Claims (19)
1. A table saw comprising:
a cutting surface;
a blade for cutting a workpiece on the cutting surface, wherein a portion of the blade is extendable above the cutting surface;
a rotatable shaft positioned below the cutting surface, wherein the blade spins when the shaft rotates;
a motor connected to the rotatable shaft for rotating the rotatable shaft; and
a kickback detection system for detecting kickback of the workpiece during cutting of the workpiece, wherein the kickback detection system comprises:
a torque sensor connected to the rotatable shaft; and
a processor in communication with the torque sensor, wherein the processor is programmed to recognize a condition indicative of kickback of the workpiece during cutting of the workpiece based on input from the torque sensor.
2. The table saw of claim 1 , further comprising a reaction means in communication with the kickback detection system for taking a mitigating reaction in response to detection of kickback of the workpiece by the kickback detection system during cutting of the workpiece.
3. The table saw of claim 2 , wherein the torque sensor comprises a strain gauge torque sensor.
4. The table saw of claim 2 , wherein the torque sensor comprises a surface acoustic wave torque sensor.
5. Table saw of claim 2 , wherein the blade is mounted to the rotatable shaft.
6. The table saw of claim 2 , further comprising:
a clutch coupled to the rotatable shaft, such that when the clutch is engaged and the motor is running, the blade shaft is rotated; and
wherein the reaction means comprises:
a brake system for braking the blade; and
a motor shut-down circuit connected to the clutch and the brake system, wherein the motor shut-down circuit disengages the clutch and actuates the brake system to brake the blade when the motor is turned off.
7. The table saw of claim 2 , further comprising a blade-spin detection means for detecting whether the blade is rotating based on energy from the blade, wherein the blade-spin detection system is in communication with the reaction means and provides an output to arm the reaction means when the blade-spin detection system detects that the blade is spinning.
8. The table saw of claim 2 , further comprising an electrical generator connected by one or more gears to the rotatable shaft, wherein the electrical generator is further connected to the reaction means and generates electricity when the shaft rotates to power at least one of the reaction means and the detection means.
9. The table saw of claims 2 , wherein the blade comprises:
an outer peripheral portion that comprises a first material; and
an inner portion that comprises a second material that is different from the first material, wherein the first material is denser than the second material.
10. The table saw of claims 2 , wherein:
the table saw further comprises a flywheel that rotates in a direction that is the same as a direction of rotation for the blade, wherein the flywheel is coupled to the rotatable shaft by a clutch; and
the reaction means disengages the clutch when the dangerous condition is detected.
11. The table saw of claim 2 , wherein the reaction means comprises a downstream kickback mitigation means that is downstream from the blade for mitigating kickback of the workpiece.
12. The table saw of claim 11 , wherein the downstream kickback mitigation means comprises moveable wing members that move to a deployed position parallel to the cutting surface and above the workpiece when triggered by the reaction means.
13. The table saw of claim 2 , further comprising a passive downstream safety member for mitigating kickback of the workpiece, wherein the passive downstream safety member is not actuated by the detection means.
14. The table saw of claim 13 , wherein the passive downstream safety member comprises angled snells that impede kickback of the workpiece.
15. The table saw of claim 2 , further comprising a suction feed assembly that feeds the workpiece to the blade for cutting.
16. The table saw of claim 2 , further comprising sensor means connected to the cutting surface for sensing a characteristic of the workpiece during cutting of the workpiece.
17. The table saw of claim 2 , further comprising a blade contact sensor means for sensing contact with by a foreign object with the blade, wherein the blade contact sensor is in communication with the reaction means, and wherein the reaction means is for taking the mitigating reaction in response to detection of contact by a foreign object with the blade upon detection by the blade contact sensor means.
18. The table saw of claim 17 , wherein:
the blade comprises:
a first electrically conductive blade portion;
a second electrically conductive blade portion that comprises teeth for cutting the workpiece; and
a dielectric between the first and second electrically conductive blade portions, and
the blade contact sensor means is connected to the first electrically conductive blade portion and drives the first electrically conductive blade portion with a drive signal, and wherein the blade contact sensor means comprises a processor for detecting contact with the blade by the object based on an electrical signal from the first electrically conductive blade portion.
19. The table saw of claim 2 , further comprising a blade proximity sensor means for sensing proximity of a foreign object to the blade, wherein the blade proximity sensor means is in communication with the reaction means, and wherein the reaction means is for taking the mitigating reaction in response to detection of proximity by a foreign object to the blade upon detection by the blade proximity sensor means.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/495,248 US20150075342A1 (en) | 2008-11-19 | 2014-09-24 | Safety mechanisms for power tools, including kickback detection system with torque sensor |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11609808P | 2008-11-19 | 2008-11-19 | |
PCT/US2009/065083 WO2010059786A1 (en) | 2008-11-19 | 2009-11-19 | Safety mechanisms for power tools |
US201113129948A | 2011-05-18 | 2011-05-18 | |
US14/495,248 US20150075342A1 (en) | 2008-11-19 | 2014-09-24 | Safety mechanisms for power tools, including kickback detection system with torque sensor |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2009/065083 Division WO2010059786A1 (en) | 2008-11-19 | 2009-11-19 | Safety mechanisms for power tools |
US13/129,948 Division US8919231B2 (en) | 2008-11-19 | 2009-11-19 | Safety mechanisms for power tools |
Publications (1)
Publication Number | Publication Date |
---|---|
US20150075342A1 true US20150075342A1 (en) | 2015-03-19 |
Family
ID=42198494
Family Applications (4)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/129,948 Active 2031-07-18 US8919231B2 (en) | 2008-11-19 | 2009-11-19 | Safety mechanisms for power tools |
US14/495,311 Abandoned US20150075343A1 (en) | 2008-11-19 | 2014-09-24 | Safety mechanisms for power tools, including magnetorhelogical brake for blade |
US14/495,248 Abandoned US20150075342A1 (en) | 2008-11-19 | 2014-09-24 | Safety mechanisms for power tools, including kickback detection system with torque sensor |
US15/497,932 Active 2030-05-24 US10632642B2 (en) | 2008-11-19 | 2017-04-26 | Table saw with table sensor for sensing characteristic of workpiece |
Family Applications Before (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/129,948 Active 2031-07-18 US8919231B2 (en) | 2008-11-19 | 2009-11-19 | Safety mechanisms for power tools |
US14/495,311 Abandoned US20150075343A1 (en) | 2008-11-19 | 2014-09-24 | Safety mechanisms for power tools, including magnetorhelogical brake for blade |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US15/497,932 Active 2030-05-24 US10632642B2 (en) | 2008-11-19 | 2017-04-26 | Table saw with table sensor for sensing characteristic of workpiece |
Country Status (2)
Country | Link |
---|---|
US (4) | US8919231B2 (en) |
WO (1) | WO2010059786A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017120165A1 (en) * | 2016-01-05 | 2017-07-13 | Milwaukee Electric Tool Corporation | Vibration reduction system and method for power tools |
DE102016211016A1 (en) * | 2016-06-21 | 2017-12-21 | Robert Bosch Gmbh | Method for operating a processing machine |
US11085582B2 (en) | 2017-08-30 | 2021-08-10 | Milwaukee Electric Tool Corporation | Power tool having object detection |
Families Citing this family (64)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7308843B2 (en) | 2000-08-14 | 2007-12-18 | Sd3, Llc | Spring-biased brake mechanism for power equipment |
DE102008000851A1 (en) * | 2008-03-27 | 2009-10-01 | Robert Bosch Gmbh | Machine tool, in particular underfloor circular table saw |
DE102008001727A1 (en) * | 2008-05-13 | 2009-11-19 | Robert Bosch Gmbh | machine tool |
US8919231B2 (en) | 2008-11-19 | 2014-12-30 | Power Tool Institute | Safety mechanisms for power tools |
US10384281B2 (en) | 2012-03-02 | 2019-08-20 | Sawstop Holding Llc | Actuators for power tool safety systems |
US8180480B2 (en) * | 2009-12-16 | 2012-05-15 | Pro-Cut Licensing Company, Llc | Tool bit monitoring for on-vehicle brake lathe |
US8534174B2 (en) | 2010-09-27 | 2013-09-17 | Power Tool Institute | Pyrotechnic actuator and power cutting tool with safety reaction system having such pyrotechnic actuator |
CA2846266A1 (en) * | 2011-08-31 | 2013-03-07 | Hirschmann Automation And Control Gmbh | Load measurement on the load receiver of hoisting devices |
US9844891B2 (en) | 2012-07-20 | 2017-12-19 | Sawstop Holding Llc | Blade tilt mechanisms for table saws |
US9952583B2 (en) * | 2012-09-28 | 2018-04-24 | Robert Bosch Tool Corporation | System and method for identification of implement motion in a power tool |
WO2014078319A1 (en) * | 2012-11-13 | 2014-05-22 | Robert Bosch Gmbh | Gworkpiece presence and/or height detection system and blade guard detection system |
US20140182430A1 (en) * | 2012-12-31 | 2014-07-03 | Robert Bosch Gmbh | Saw Device with Detection System |
WO2014105935A1 (en) * | 2012-12-31 | 2014-07-03 | Robert Bosch Gmbh | Kichback detection system |
US20160016240A1 (en) * | 2013-03-12 | 2016-01-21 | Robert Bosch Gmbh | Workpiece Material Detector for a Power Tool |
CN105592963B (en) | 2013-03-14 | 2018-03-09 | 罗伯特·博世有限公司 | For pivoting the automatic breaking system and its operating method of electric tool |
AU2014348859A1 (en) | 2013-11-18 | 2016-06-09 | Robert Bosch Gmbh | Power tool with capacitive injury mitigation system |
CN103909445B (en) * | 2014-04-16 | 2016-05-18 | 徐震 | Band sawing machine auto-adaptive cutting control device |
TWI549776B (en) * | 2014-05-02 | 2016-09-21 | 邱智煇 | A protective apparatus and a machine tool |
US11097393B2 (en) * | 2014-05-02 | 2021-08-24 | Chih-Hui Chiu | Protective apparatus for a machine tool |
EP3180169B1 (en) * | 2014-08-12 | 2019-03-27 | Robert Bosch GmbH | System and method for kickback detection in a circular saw |
CN107000087B (en) * | 2014-09-25 | 2019-12-03 | 罗伯特·博世有限公司 | The system and method for recalcitrating detection are carried out based on the blade speed in power tool |
US20160182833A1 (en) * | 2014-12-23 | 2016-06-23 | Signazon.Com | Camera System for Cutting Table |
US10758989B2 (en) * | 2015-03-12 | 2020-09-01 | Robert Bosch Tool Corporation | System and method for sensing cable fault detection in a saw |
US9849527B2 (en) * | 2015-03-12 | 2017-12-26 | Robert Bosch Tool Corporation | Power tool with lightweight actuator housing |
US10369642B2 (en) | 2015-03-12 | 2019-08-06 | Robert Bosch Tool Corporation | Power tool with protected circuit board orientation |
US10821529B2 (en) | 2015-03-12 | 2020-11-03 | Robert Bosch Tool Corporation | Power tool with improved belt tensioning |
US10427227B2 (en) | 2015-03-12 | 2019-10-01 | Robert Bosch Tool Corporation | Drop arm reset method |
US10099399B2 (en) * | 2015-03-12 | 2018-10-16 | Robert Bosch Tool Corporation | Object proximity detection in a saw |
US10786854B2 (en) | 2015-03-12 | 2020-09-29 | Robert Bosch Tool Corporation | Table saw with electrically isolated arbor shaft |
US9969015B2 (en) | 2015-03-12 | 2018-05-15 | Robert Bosch Tool Corporation | Power tool with protected coupling plate |
US10322522B2 (en) * | 2015-03-12 | 2019-06-18 | Robert Bosch Tool Corporation | Electrical configuration for object detection system in a saw |
US10493543B2 (en) | 2015-03-12 | 2019-12-03 | Robert Bosch Tool Corporation | Power tool motor with reduced electrical noise |
US9868167B2 (en) * | 2015-03-12 | 2018-01-16 | Robert Bosch Tool Corporation | Power tool with drop arm orbit bracket |
US10105863B2 (en) * | 2015-03-12 | 2018-10-23 | Robert Bosch Tool Corporation | System and method for object and operator profiling in an object detection system in a saw |
US10799964B2 (en) | 2015-03-12 | 2020-10-13 | Robert Bosch Tool Corporation | Table saw with pulley alignment mechanism |
US10189098B2 (en) * | 2015-03-12 | 2019-01-29 | Robert Bosch Tool Corporation | Diagnostic and maintenance operation for a saw |
TWI675712B (en) * | 2015-03-12 | 2019-11-01 | 德商羅伯特博斯奇股份有限公司 | Power tool with pyrotechnic lockout |
US10722959B2 (en) | 2015-06-01 | 2020-07-28 | Sawstop Holding Llc | Table saw |
US9810524B2 (en) * | 2015-12-15 | 2017-11-07 | Sears Brands, L.L.C. | Power tool with optical measurement device |
WO2017168226A1 (en) | 2016-03-30 | 2017-10-05 | 3D Signals Ltd. | Acoustic monitoring of machinery |
HUE041970T2 (en) * | 2016-09-28 | 2019-06-28 | Scheppach Fabrikation Holzbearbeitungsmaschinen Gmbh | Table saw and push stick for it |
US10839076B2 (en) | 2016-12-21 | 2020-11-17 | 3D Signals Ltd. | Detection of cyber machinery attacks |
US10906110B2 (en) | 2017-04-28 | 2021-02-02 | Transform Sr Brands Llc | Power tool with integrated measurement device and associated methods |
DE202017103019U1 (en) * | 2017-05-18 | 2018-08-21 | Wilhelm Altendorf Gmbh & Co. Kg | Safety device for a sliding table saw |
EP3403762B1 (en) * | 2017-05-19 | 2023-09-13 | Felder KG | Machine tool with safety system |
US10933554B2 (en) | 2017-05-25 | 2021-03-02 | Sawstop Holding Llc | Power saws |
US11491564B2 (en) | 2017-07-24 | 2022-11-08 | Festool Gmbh | Power tool, system, and method |
KR102443014B1 (en) | 2017-07-24 | 2022-09-14 | 페스툴 게엠베하 | Power tools and methods |
US11078978B2 (en) | 2017-09-29 | 2021-08-03 | Rockwell Automation Technologies, Inc. | Motor brake system |
US10520054B2 (en) * | 2017-09-29 | 2019-12-31 | Rockwell Automation Technologies, Inc. | Motor brake system |
EP3495899A1 (en) * | 2017-12-06 | 2019-06-12 | HILTI Aktiengesellschaft | System and method for an automatic safety protocol in electrical tools |
US20190234559A1 (en) * | 2018-01-31 | 2019-08-01 | Hollymatic Corporation | Method and system to monitor and shut down saw |
CN108890787B (en) * | 2018-07-03 | 2020-07-03 | 东宁晟(北京)数字科技有限公司 | Six-drive intelligent control cutting vehicle |
DE102018216552A1 (en) * | 2018-09-27 | 2020-04-02 | Robert Bosch Gmbh | Actuators for a braking element |
DE102018216546A1 (en) * | 2018-09-27 | 2020-04-02 | Robert Bosch Gmbh | Safety brake device |
US10916259B2 (en) | 2019-01-06 | 2021-02-09 | 3D Signals Ltd. | Extracting overall equipment effectiveness by analysis of a vibro-acoustic signal |
DE202019102935U1 (en) * | 2019-05-24 | 2020-08-25 | Altendorf Gmbh | Safety device for machine tools |
DE102019219827A1 (en) * | 2019-12-17 | 2021-06-17 | Robert Bosch Gesellschaft mit beschränkter Haftung | Brake system for a handheld power tool with at least one brake unit |
DE102019219819A1 (en) * | 2019-12-17 | 2021-06-17 | Robert Bosch Gesellschaft mit beschränkter Haftung | Brake system for a handheld power tool with at least one brake unit |
DE102020125455A1 (en) * | 2020-09-29 | 2022-03-31 | MAFELL Aktiengesellschaft | processing machine |
DE202021100243U1 (en) | 2021-01-19 | 2022-04-20 | Altendorf Gmbh | Format circular saw with safety device to avoid cut injuries |
WO2023069283A1 (en) * | 2021-10-18 | 2023-04-27 | Schlumberger Technology Corporation | Instrumented saw blade |
US20230166343A1 (en) * | 2021-11-30 | 2023-06-01 | Nanjing Chervon Industry Co., Ltd. | Table tool and control method therefor |
DE202022101212U1 (en) | 2022-03-04 | 2023-06-07 | Altendorf Gmbh | Safety device for a machine tool |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5584619A (en) * | 1993-12-28 | 1996-12-17 | Hilti Aktiengesellschaft | Method of and arrangement for preventing accidents during operation of a manually-operated machine tool with a rotatable toolbit |
US7055417B1 (en) * | 1999-10-01 | 2006-06-06 | Sd3, Llc | Safety system for power equipment |
US7111611B1 (en) * | 2005-09-21 | 2006-09-26 | Daimlerchrysler Corporation | Torque sensor-based engine and powertrain control system |
US7293476B2 (en) * | 2004-08-20 | 2007-11-13 | Honeywell International Inc. | Power sensor module for engine transmission and driveline applications |
US7307517B2 (en) * | 2005-08-05 | 2007-12-11 | Honeywell International Inc. | Wireless torque sensor |
US20080311795A1 (en) * | 2007-06-15 | 2008-12-18 | Brotto Daniele C | Adapter for cordless power tools |
Family Cites Families (77)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2772394A (en) * | 1951-12-28 | 1956-11-27 | United Shoe Machinery Corp | Devices for finding protruding metal objects in shoes |
US3371272A (en) * | 1964-09-09 | 1968-02-27 | Stanton Joshua Clarke | Electromagnetic sensing probe structure and system for gaging proximity of metals and the like utilizing a linear variable differential transformer |
US4145940A (en) * | 1978-01-26 | 1979-03-27 | Woloveke Eugene L | Brake apparatus for a motor driven saw blade |
US4267914A (en) * | 1979-04-26 | 1981-05-19 | Black & Decker Inc. | Anti-kickback power tool control |
US4920495A (en) * | 1988-07-15 | 1990-04-24 | Gfm Holdings Ag | Sheet cutting machine |
US5070751A (en) * | 1991-01-11 | 1991-12-10 | Harris Gerald R | Apparatus for detecting lateral deviation of a band saw blade |
US5816372A (en) * | 1994-09-09 | 1998-10-06 | Lord Corporation | Magnetorheological fluid devices and process of controlling force in exercise equipment utilizing same |
ATE225486T1 (en) | 1995-09-25 | 2002-10-15 | Jorn Sorensen | METHOD AND DEVICE FOR DETECTING THE DISTANCE BETWEEN A FIRST OBJECT AND A SECOND OBJECT |
US5758561A (en) * | 1995-09-26 | 1998-06-02 | Black & Decker Inc. | Circular saw blade and method |
DE19614418C1 (en) * | 1996-04-12 | 1997-06-12 | Altendorf Wilhelm Gmbh Co Kg | Motorised feed-drive control e.g. for circular saw carriage |
US5905440A (en) * | 1997-12-19 | 1999-05-18 | Battelle Memorial Institute | Acoustic emission severance detector and method |
US6234060B1 (en) * | 1999-03-08 | 2001-05-22 | Lord Corporation | Controllable pneumatic apparatus including a rotary-acting brake with field responsive medium and control method therefor |
US6302249B1 (en) * | 1999-03-08 | 2001-10-16 | Lord Corporation | Linear-acting controllable pneumatic actuator and motion control apparatus including a field responsive medium and control method therefor |
US6536536B1 (en) | 1999-04-29 | 2003-03-25 | Stephen F. Gass | Power tools |
US9927796B2 (en) | 2001-05-17 | 2018-03-27 | Sawstop Holding Llc | Band saw with improved safety system |
US20050139459A1 (en) | 2003-12-31 | 2005-06-30 | Gass Stephen F. | Switch box for power tools with safety systems |
US20060219076A1 (en) | 2005-03-31 | 2006-10-05 | Gass Stephen F | Table saw throat plates and table saws including the same |
US7024975B2 (en) | 2000-08-14 | 2006-04-11 | Sd3, Llc | Brake mechanism for power equipment |
US6945149B2 (en) | 2001-07-25 | 2005-09-20 | Sd3, Llc | Actuators for use in fast-acting safety systems |
US20030056853A1 (en) * | 2001-09-21 | 2003-03-27 | Gass Stephen F. | Router with improved safety system |
US20030037651A1 (en) | 2001-08-13 | 2003-02-27 | Gass Stephen F. | Safety systems for power equipment |
US20050041359A1 (en) | 2003-08-20 | 2005-02-24 | Gass Stephen F. | Motion detecting system for use in a safety system for power equipment |
US7197969B2 (en) | 2001-09-24 | 2007-04-03 | Sd3, Llc | Logic control with test mode for fast-acting safety system |
US7707920B2 (en) | 2003-12-31 | 2010-05-04 | Sd3, Llc | Table saws with safety systems |
US7098800B2 (en) | 2003-03-05 | 2006-08-29 | Sd3, Llc | Retraction system and motor position for use with safety systems for power equipment |
US7231856B2 (en) | 2001-06-13 | 2007-06-19 | Sd3, Llc | Apparatus and method for detecting dangerous conditions in power equipment |
US7308843B2 (en) | 2000-08-14 | 2007-12-18 | Sd3, Llc | Spring-biased brake mechanism for power equipment |
US20040040426A1 (en) | 2002-08-27 | 2004-03-04 | Gass Stephen F. | Miter saw with improved safety system |
US20030131703A1 (en) | 2002-01-16 | 2003-07-17 | Gass Stephen F. | Apparatus and method for detecting dangerous conditions in power equipment |
US7377199B2 (en) | 2000-09-29 | 2008-05-27 | Sd3, Llc | Contact detection system for power equipment |
US7640835B2 (en) | 2000-08-14 | 2010-01-05 | Sd3, Llc | Apparatus and method for detecting dangerous conditions in power equipment |
US7171879B2 (en) | 2001-07-02 | 2007-02-06 | Sd3, Llc | Discrete proximity detection system |
US7100483B2 (en) | 2000-08-14 | 2006-09-05 | Sd3, Llc | Firing subsystem for use in a fast-acting safety system |
US6920814B2 (en) | 2000-08-14 | 2005-07-26 | Sd3, Llc | Cutting tool safety system |
US7509899B2 (en) | 2000-08-14 | 2009-03-31 | Sd3, Llc | Retraction system for use in power equipment |
US7225712B2 (en) | 2000-08-14 | 2007-06-05 | Sd3, Llc | Motion detecting system for use in a safety system for power equipment |
US7210383B2 (en) | 2000-08-14 | 2007-05-01 | Sd3, Llc | Detection system for power equipment |
US7284467B2 (en) | 2000-08-14 | 2007-10-23 | Sd3, Llc | Apparatus and method for detecting dangerous conditions in power equipment |
US7827890B2 (en) | 2004-01-29 | 2010-11-09 | Sd3, Llc | Table saws with safety systems and systems to mount and index attachments |
US9724840B2 (en) | 1999-10-01 | 2017-08-08 | Sd3, Llc | Safety systems for power equipment |
US7077039B2 (en) | 2001-11-13 | 2006-07-18 | Sd3, Llc | Detection system for power equipment |
US7350444B2 (en) | 2000-08-14 | 2008-04-01 | Sd3, Llc | Table saw with improved safety system |
US7600455B2 (en) | 2000-08-14 | 2009-10-13 | Sd3, Llc | Logic control for fast-acting safety system |
US7536238B2 (en) | 2003-12-31 | 2009-05-19 | Sd3, Llc | Detection systems for power equipment |
US6994004B2 (en) | 2000-09-29 | 2006-02-07 | Sd3, Llc | Table saw with improved safety system |
US7712403B2 (en) | 2001-07-03 | 2010-05-11 | Sd3, Llc | Actuators for use in fast-acting safety systems |
US8646369B2 (en) | 2007-10-01 | 2014-02-11 | Sd3, Llc | Table saw guards, splitter assemblies, accessories, and table saws including the same |
US8061245B2 (en) | 2000-09-29 | 2011-11-22 | Sd3, Llc | Safety methods for use in power equipment |
US7481140B2 (en) | 2005-04-15 | 2009-01-27 | Sd3, Llc | Detection systems for power equipment |
US7000514B2 (en) | 2001-07-27 | 2006-02-21 | Sd3, Llc | Safety systems for band saws |
US7789002B2 (en) | 2000-09-29 | 2010-09-07 | Sd3, Llc | Table saw with improved safety system |
US7971613B2 (en) | 2007-12-31 | 2011-07-05 | Sd3, Llc | Detection systems for power equipment |
US6950814B2 (en) | 2000-06-24 | 2005-09-27 | International Business Machines Corporation | Natural language processing methods and systems |
US6813983B2 (en) | 2000-09-29 | 2004-11-09 | Sd3, Llc | Power saw with improved safety system |
AT409470B (en) * | 2000-10-31 | 2002-08-26 | Kuchler Fritz | ARRANGEMENT OF CUTTING THICKNESS ON A SLICER |
CA2448479C (en) | 2002-11-12 | 2009-05-05 | Makita Corporation | Power tools |
DE10261791A1 (en) * | 2002-12-23 | 2004-07-15 | Robert Bosch Gmbh | Device for protection against accidental contact and method for protecting against contact with a moving part |
US20040194594A1 (en) * | 2003-01-31 | 2004-10-07 | Dils Jeffrey M. | Machine safety protection system |
US7698975B2 (en) | 2003-01-31 | 2010-04-20 | Techtronic Power Tools Technology Limited | Table saw with cutting tool retraction system |
US7290474B2 (en) | 2003-04-29 | 2007-11-06 | Black & Decker Inc. | System for rapidly stopping a spinning table saw blade |
US6922153B2 (en) | 2003-05-13 | 2005-07-26 | Credo Technology Corporation | Safety detection and protection system for power tools |
JP4271511B2 (en) | 2003-06-27 | 2009-06-03 | 株式会社マキタ | Radar device and distance and reflectance measurement method |
US7077037B2 (en) | 2003-10-31 | 2006-07-18 | Spx Corporation | Apparatus and method for removing a bolt from an assembly |
JP2007538301A (en) * | 2004-01-29 | 2007-12-27 | プレー・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツング | Programmable rotational torque supply device using spring parts |
US7628101B1 (en) | 2006-03-13 | 2009-12-08 | Power Tool Institute | Pyrotechnic drop mechanism for power tools |
US7804204B1 (en) | 2005-05-19 | 2010-09-28 | Power Tool Institute | Capacitive sensing system for power cutting tool |
US7421932B1 (en) | 2005-05-19 | 2008-09-09 | Power Tool Institute | Power cutting tool comprising a radar sensing system |
US20060288992A1 (en) * | 2005-06-27 | 2006-12-28 | Anthony Baratta | Tools and methods for making and using tools, blades and methods of making and using blades |
US20070176035A1 (en) * | 2006-01-30 | 2007-08-02 | Campbell John P | Rotary motion control device |
US7599223B2 (en) | 2006-09-12 | 2009-10-06 | Sandisk Corporation | Non-volatile memory with linear estimation of initial programming voltage |
US20090241745A1 (en) | 2008-03-25 | 2009-10-01 | Power Tool Institute | Guard, riving knife, and anti-kickback pawl assembly |
US8091456B2 (en) * | 2008-03-25 | 2012-01-10 | Power Tool Institute | Safety devices for saws |
DE102008000891A1 (en) * | 2008-03-31 | 2009-10-01 | Robert Bosch Gmbh | Protection system for machine tools |
US7739934B2 (en) | 2008-09-08 | 2010-06-22 | Power Tool Institute | Detection system for power tool |
US8919231B2 (en) | 2008-11-19 | 2014-12-30 | Power Tool Institute | Safety mechanisms for power tools |
US20100307308A1 (en) | 2009-06-09 | 2010-12-09 | Butler David J | Blade enclosure for a table saw |
US8082825B2 (en) | 2009-06-09 | 2011-12-27 | Butler David J | Health and safety system for a table saw |
-
2009
- 2009-11-19 US US13/129,948 patent/US8919231B2/en active Active
- 2009-11-19 WO PCT/US2009/065083 patent/WO2010059786A1/en active Application Filing
-
2014
- 2014-09-24 US US14/495,311 patent/US20150075343A1/en not_active Abandoned
- 2014-09-24 US US14/495,248 patent/US20150075342A1/en not_active Abandoned
-
2017
- 2017-04-26 US US15/497,932 patent/US10632642B2/en active Active
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5584619A (en) * | 1993-12-28 | 1996-12-17 | Hilti Aktiengesellschaft | Method of and arrangement for preventing accidents during operation of a manually-operated machine tool with a rotatable toolbit |
US7055417B1 (en) * | 1999-10-01 | 2006-06-06 | Sd3, Llc | Safety system for power equipment |
US7293476B2 (en) * | 2004-08-20 | 2007-11-13 | Honeywell International Inc. | Power sensor module for engine transmission and driveline applications |
US7307517B2 (en) * | 2005-08-05 | 2007-12-11 | Honeywell International Inc. | Wireless torque sensor |
US7111611B1 (en) * | 2005-09-21 | 2006-09-26 | Daimlerchrysler Corporation | Torque sensor-based engine and powertrain control system |
US20080311795A1 (en) * | 2007-06-15 | 2008-12-18 | Brotto Daniele C | Adapter for cordless power tools |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017120165A1 (en) * | 2016-01-05 | 2017-07-13 | Milwaukee Electric Tool Corporation | Vibration reduction system and method for power tools |
US11014224B2 (en) | 2016-01-05 | 2021-05-25 | Milwaukee Electric Tool Corporation | Vibration reduction system and method for power tools |
DE102016211016A1 (en) * | 2016-06-21 | 2017-12-21 | Robert Bosch Gmbh | Method for operating a processing machine |
US11085582B2 (en) | 2017-08-30 | 2021-08-10 | Milwaukee Electric Tool Corporation | Power tool having object detection |
US11674642B2 (en) | 2017-08-30 | 2023-06-13 | Milwaukee Electric Tool Corporation | Power tool having object detection |
Also Published As
Publication number | Publication date |
---|---|
US8919231B2 (en) | 2014-12-30 |
US20150075343A1 (en) | 2015-03-19 |
WO2010059786A1 (en) | 2010-05-27 |
US10632642B2 (en) | 2020-04-28 |
US20110226105A1 (en) | 2011-09-22 |
US20170225351A1 (en) | 2017-08-10 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US10632642B2 (en) | Table saw with table sensor for sensing characteristic of workpiece | |
EP1622748B1 (en) | A table saw with a saw retracting system | |
US9446533B2 (en) | Power tool safety mechanisms | |
US7225712B2 (en) | Motion detecting system for use in a safety system for power equipment | |
JP5043267B2 (en) | Safety system for power equipment | |
US7377199B2 (en) | Contact detection system for power equipment | |
CA2448479C (en) | Power tools | |
US20040159198A1 (en) | Table saw with cutting tool retraction system | |
US20060254401A1 (en) | Detection system for power equipment | |
CN116963885A (en) | Dicing saw with safety device for avoiding cutting injuries | |
TW201808521A (en) | Blade guard having a safety feature |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: POWER TOOL INSTITUTE, OHIO Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BUTLER, ANDY;LAMB, BRIAN;LAZZARI, CLINTON;AND OTHERS;SIGNING DATES FROM 20110217 TO 20141115;REEL/FRAME:036494/0846 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |