Band saw with safety system

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BAND SAW WITH SAFETY SYSTEM

CROSS-REFERENCE TO RELATED
APPLICATIONS

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This application is a divisional continuation application of U.S. patent application Ser. No. 10/146,527, filed May 15, 2002, which claims the benefit of and priority from U.S. Provisional Patent Application Ser. No. 60/292,100, filed May 17, 2001. This application is also a continuation of the 10 following U.S. patent applications Ser. No. 09/676,190, filed Sep. 29, 2000, now U.S. Pat. No. 7,055,417,which claims the benefit of and priority from U.S. Provisional Patent Application Ser. No. 60/157,340 filed Oct. 1, 1999 and U.S. Provisional Patent Application Ser. No. 60/182,866 filed Feb. 16, 15 2000; Ser. No. 09/929,426, filedAug. 13,2001, now U.S. Pat. No. 7,210,383, which claims the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,200 filedAug. 14, 2000; Ser. No. 09/929,221, filedAug. 13,2001, now U.S. Pat. 20 No. 7,284,467, which claims the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,211 filedAug. 14, 2000; Ser. No. 09/929,240, filedAug. 13,2001, now U.S. Pat. No. 7,100,483, which claims the benefit of and priority from 25 a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,056 filedAug. 14, 2000; Ser. No. 09/929,227, filedAug. 13,2001, now U.S. Pat. No. 7,308,843,which claims the benefit of and priority from a number of provisional applications including U.S. Provi- 30 sional Patent Application Ser. No. 60/225,170 filedAug. 14, 2000; Ser. No. 09/929,241, filedAug. 13,2001, now U.S. Pat. No. 7,024,975, which claims the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,169 filedAug. 14, 35 2000; Ser. No. 09/929,242, filedAug. 13, 2001, which claims the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,089 filedAug. 14,2000; Ser. No. 09/929,236, filedAug. 13, 2001, which claims the benefit of and priority 40 from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,201 filedAug. 14, 2000; Ser. No. 11/061,162 filed Feb. 18, 2005, now U.S. Pat. No. 7,228,772, which is a continuation of U.S. patent application Ser. No. 09/929,244 filedAug. 13, 2001 and issu- 45 ing as U.S. Pat. No. 6,857,345 on Feb. 22, 2005 and which claimed the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,212 filed Aug. 14, 2000; Ser. No. 09/929,237, filedAug. 13, 2001, which claims the benefit of 50 and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,059 filed Aug. 14, 2000; Ser. No. 09/929,234, filed Aug. 13,2001, now U.S. Pat. No. 7,225,712, which claims the benefit of and priority from a number of provisional applica- 55 tions including U.S. Provisional Patent Application Ser. No. 60/225,094 filed Aug. 14, 2000; Ser. No. 09/929,425, filed Aug. 13,2001, now U.S. Pat. No. 7,137,326, which claims the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60 60/225,210 filedAug. 14,2000; Ser. No. 11/190,111 filed Jul. 25, 2005, now U.S. Pat. No. 7,357,056, which is a continuation of a number of applications including U.S. patent application Ser. No. 09/929,226, filedAug. 13,2001 and issuing as U.S. Pat. No. 6,920,814 on Jul. 26, 2005 and which claimed 65 the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application

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Ser. No. 60/225,206; Ser. No. 09/929,235, filed Aug. 13, 2001, now U.S. Pat. No. 7,350,444, which claims the benefit of and priority from a number of provisional applications including U.S. Provisional Patent Application Ser. No. 60/225,058 filedAug. 14, 2000. All of these applications are hereby incorporated by reference in their entirety for all purposes.

This application also hereby incorporates by reference the following PCT patent application: PCT/US00/26812, filed Sep. 29, 2000.

This application further incorporates by reference the following U.S. provisional patent applications: Ser. No. 60/233, 459, filed Sep. 18, 2000, Ser. No. 60/270,011, filed Feb. 20, 2001, Ser. No. 60/270,941, filed Feb. 22, 2001, Ser. No. 60/270,942, filed Feb. 22, 2001, Ser. No. 60/273,178, filed Mar. 2,2001, Ser. No. 60/273,177, filed Mar. 2,2001, Ser. No. 60/273,902, filed Mar. 6, 2001, Ser. No. 60/275,594, filed Mar. 13, 2001, Ser. No. 60/275,595, filed Mar. 13, 2001, Ser. No. 60/275,583, filed Mar. 13, 2001, Ser. No. 60/279,313, filed Mar. 27, 2001, and Ser. No. 60/292,081, filed May 17, 2001.

FIELD

The present invention relates to band saws, and more particularly to a band saw with a high-speed safety system.

BACKGROUND

Band saws are a type of woodworking machinery used to cut workpieces of wood, plastic, and other materials. Band saws include two, spaced-apart wheels, and a blade tightly looped around the wheels. The blade is made from a band of metal with teeth on one edge of the band. The blade moves around the wheels when the wheels spin. Band saws also include a table or work surface adjacent the blade and upon which workpieces are placed. A person uses the band saw by placing a workpiece on the table and then sliding the workpiece into the moving blade. Band saws present a risk of injury to users because the blade is exposed when in use. Furthermore, users often must place their hands very close to the blade to position and move workpieces, which increases the chance that an injury will occur.

The present invention provides a band saw with an improved safety system that is adapted to detect the occurrence of one or more dangerous, or triggering, conditions during use of the band saw, such as when a user's body contacts the moving blade. When such a condition occurs, the safety system is actuated to limit or even prevent injury to the user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a band saw with a fast-acting safety system according to the present invention.

FIG. 2 is a schematic side elevation of an embodiment of a band saw according to the present invention.

FIG. 3 shows a wheel mount with a capacitive coupling used in the band saw of FIG. 2.

FIG. 4 shows a wheel mount used in the band saw of FIG.

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FIG. 5 shows schematically a reaction subsystem that stops a blade by cutting and gripping the blade.

FIG. 6 is a schematic representation of one embodiment of a cutting pawl and backing plate used in a reaction system that stops a blade by cutting the blade.

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FIG. 7 is a schematic top view of another embodiment of cutting pawls used in a reaction system to stop a blade by cutting the blade.

FIG. 8 is a schematic front view of the cutting pawls shown in FIG. 7. 5

DETAILED DESCRIPTION AND BEST MODE

A band saw according to the present invention is shown schematically in FIG. 1 and indicated generally at 10. Band 10 saw 10 may be any of a variety of different types and configurations of band saws adapted for cutting workpieces, such as wood and plastic. Band saw 10 includes an operative structure 12 having a blade 14 and a motor assembly 16 adapted to drive the blade. Band saw 10 also includes a safety 15 system 18 configured to minimize the potential of a serious injury to a person using the band saw. Safety system 18 is adapted to detect the occurrence of one or more dangerous, or triggering, conditions during use of band saw 10. If such a dangerous condition is detected, safety system 18 is adapted 20 to engage operative structure 12 to limit any injury to the user caused by the dangerous condition.

Band saw 10 includes a suitable power source 20 to provide power to operative structure 12 and safety system 18. Power source 20 may be an external power source such as line current, or an internal power source such as a battery. Alternatively, power source 20 may include a combination of both external and internal power sources. Furthermore, power source 20 may include two or more separate power sources, 3Q each adapted to power different portions of band saw 10.

It will be appreciated that operative structure 12 may take any one of many different forms, depending on the type of band saw 10. As will be described in more detail below, operative structure 12 typically includes two, spaced-apart 35 wheels and a table adjacent the wheels. A blade 14, made from a band of metal with teeth along one edge of the band, is positioned around the wheels adjacent the table. Motor assembly 16 includes one or more motors adapted to drive blade 14 by spinning at least one of the wheels around which 4Q the blade is positioned.

Safety system 18 includes a detection subsystem 22, a reaction subsystem 24 and a control subsystem 26. Control subsystem 26 may be adapted to receive inputs from a variety of sources including detection subsystem 22, reaction sub- 45 system24, operative structure 12 andmotor assembly 16. The control subsystem may also include one or more sensors adapted to monitor selected parameters of band saw 10. In addition, control subsystem 26 typically includes one ormore instruments operable by a user to control the band saw. The 50 control subsystem is configured to control band saw 10 in response to the inputs it receives.

Detection subsystem 22 is configured to detect one ormore dangerous, or triggering, conditions during use of band saw 10. For example, the detection subsystem may be configured 55 to detect that a portion of the user's body is in contact with a portion of blade 14. In some embodiments, detection subsystem 22 may inform control subsystem 26 of the dangerous condition, which then activates reaction subsystem 24. In other embodiments, the detection subsystem may be adapted 60 to activate the reaction subsystem directly. Various exemplary embodiments and implementations of detection subsystem 22 are described in more detail in U.S. Provisional Patent Application Ser. No. 60/225,200, entitled "Contact Detection System for Power Equipment," filed Aug. 14, 2000, by SD3, 65 LLC, the disclosure of which is incorporated herein by reference.

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Once activated in response to a dangerous condition, reaction subsystem 24 is configured to quickly engage operative structure 12 to prevent serious injury to the user. It will be appreciated that the particular action to be taken by reaction subsystem 24 will vary depending on the type of band saw 10 and/or the dangerous condition that is detected. For example, reaction subsystem 24 may be configured to do one or more of the following: stop the movement of blade 14 by cutting the blade and/or by gripping the blade, disconnect motor assembly 16 from power source 20, retract the blade from its operating position, etc.

The configuration of reaction subsystem 24 typically will vary depending on which action(s) are taken. In the exemplary embodiment depicted in FIG. 1, reaction subsystem 24 is configured to stop the movement of blade 14 and includes a brake mechanism 28, a biasing mechanism 30, a restraining mechanism 32, and a release mechanism 34. Brake mechanism 28 is adapted to engage operative structure 12 under the urging of biasing mechanism 30. During normal operation of band saw 10, restraining mechanism 32 holds the brake mechanism out of engagement with the operative structure. However, upon receipt of an activation signal by reaction subsystem 24, the brake mechanism is released from the restraining mechanism by release mechanism 34, whereupon, the brake mechanism quickly engages at least a portion of the operative structure to bring the blade to a stop.

Control subsystem 26 includes one or more instruments that are operable by a user to control the motion of blade 14. Those instruments may include start/stop switches, speed controls, etc. Control subsystem 26 typically includes a logic controller connected to receive the user's inputs via the instruments. The logic controller is also connected to receive a contact detection signal from detection subsystem 22. Further, the logic controller may be configured to receive inputs from other sources, such as blade motion sensors, workpiece sensors, etc. In any event, the logic controller is configured to control operative structure 12 in response to the user's inputs. However, upon receipt of a contact detection signal from detection subsystem 22, the logic controller overrides the control inputs from the user and activates reaction subsystem 24 to stop the motion of the blade. Various exemplary embodiments and implementations of control subsystem 26, including the logic controller, are described in more detail in U.S. Provisional Patent Application Ser. No. 60/225,059, entitled "Logic Control For Fast Acting Safety System," filed Aug. 14, 2000 by SD3, LLC, and in U.S. Provisional Patent Application Ser. No. 60/225,094, entitled "Motion Detecting System For Use In Safety System For Power Equipment," filed Aug. 14, 2000 by SD3, LLC, the disclosures of which are herein incorporated by reference.

One embodiment of band saw 10 is shown specifically in FIG. 2. It includes a main housing 50 enclosing a pair of spaced-apart wheels 52 and 54. Wheels 52 and 54 are supported for rotational movement by housing 50. Housing 50 also typically encloses the wheels to prevent a user from touching them while they are spinning. The perimeter of each wheel may be coated or covered in a high-friction material such as rubber, etc. A relatively thin, continuous loop, toothedged blade 14 tightly encircles both wheels. Wheel 54 is driven by motor assembly 16 (not shown in FIG. 2) so that it rotates in the direction of arrow 56. Rotating wheel 54 causes blade 14 to move, which in turn, causes wheel 52 to rotate. Blade 14 moves adjacent table 58. A workpiece is cut by sliding the workpiece on table 58 into the teeth of moving blade 14 between wheels 52 and 54. An upper blade-guide assembly 60 and a lower blade-guide assembly 62 maintain the moving blade in a stable path.