Safety detection and protection system for power tools

• US 20050268767A1
• Filed: 07/25/2005
• Published: 12/08/2005
• Est. Priority Date: 05/13/2003
• Status: Active Grant

• Current Assignee: Credo Technology Corporation (Robert Bosch GmbH)
• Original Assignee: Credo Technology Corporation (Robert Bosch GmbH)
• Inventors: Pierga, Wojciech T., Siwek, Thomas R., Shishegar, Ahmad R.
• Granted Patent: US 8,640,583 B2
• Time in Patent Office: Days
• US Class Current: 83/581
• CPC Class Codes: B23D 45/06 with a circular saw blade arranged underneath a stationary work-table
• CPC Class Codes: B23D 45/067 the saw blade being adjustable according to depth or angle of cut
• CPC Class Codes: B23D 47/08 of devices for bringing the circular saw blade to the workpiece or removing same therefrom
• CPC Class Codes: B23D 59/001 Measuring or control devices, e.g. for automatic control of work feed pressure on band saw blade measuring in general G01; controlling in general G05
• CPC Class Codes: B27G 19/02 for circular saws
• CPC Class Codes: F16P 3/12 with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine F16P3/08 takes precedence
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]
• CPC Class Codes: Y10T 83/8773 Bevel or miter cut
• CPC Class Codes: Y10T 83/9372 Rotatable type
• CPC Class Codes: Y10T 83/9384 Notching plus nonnotching tool

Abstract

A detection system for detecting a dangerous condition for an operator using a power tool of the type which has an exposed blade relative to a work surface and a protection system for minimizing, if not eliminating the possibility of a user being injured by contacting the blade. In one preferred embodiment of the present invention, a proximity detection system is capable of detecting the presence of a user near the blade of a table saw and a protection system that can either retract the blade below the work surface of the table saw or terminate the drive torque to the blade which can result in rapid stopping of the saw blade by a work piece that is being cut.

Claims

1-45. -45. (canceled)

46. A table saw comprising:

a frame structure with a generally flat work surface;

a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece;

a drive motor with an output shaft mounted to the frame structure for powering the saw blade;

a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence of a person in contact or in close proximity thereto; and

a pyrotechnic actuator driven retracting mechanism located beneath said work surface for rapidly moving the blade downwardly below the work surface responsive to said first actuation signal being received.

47. A table saw as defined in claim 46 wherein said retracting mechanism comprises:

an arm structure that has a first pulley operatively coupled to said arbor, a second pulley operatively coupled to said output shaft of said drive motor and a flexible belt coupling said first and second pulleys, said arm structure pivoting about an axis concentric with said second pulley so that the tension in said belt is relatively constant regardless of the position of the blade relative to said work surface; and

a pyrotechnic actuator connected to said frame structure and said arm structure for rapidly moving said arm structure to cause said blade to be moved below said work surface responsive to receiving said first actuation signal from said sensing mechanism.

48. A table saw as defined in claim 47 wherein said pyrotechnic actuator is a device having a housing and an elongated rod extending therefrom, actuation of said device causing said rod to move longitudinally relative to said housing, one of the end of said rod and housing being connected to said frame structure and the other of the end of said rod and housing being connected to said arm structure.

49. A table saw as defined in claim 47 wherein said arm structure has a transverse extension extending from near said second pulley, said arm structure being generally L shaped, with said actuator being connected to said transverse extension.

50. A table saw as defined in claim 49 wherein the outer end of said transverse extension has a curved surface containing a plurality of teeth for engaging a worm gear, said arm structure including an elongated shaft having a worm gear portion and an a elevation crank attached to one end thereof for incrementally adjusting the amount of said blade that is above the work surface, said elongated shaft being longitudinally movable relative to said frame structure, said actuator being operatively attached to said shaft such that said shaft can be longitudinally moved while permitting rotation thereof.

51. A table saw comprising:

a frame structure with a generally flat work surface;

a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece;

a drive motor with an output shaft mounted to the frame structure for powering the saw blade;

a sensing mechanism for generating at least a first actuation signal responsive to predetermined sensed characteristics relating to the existence of a person at least in close proximity thereto;

a pyrotechnic retracting mechanism located beneath said work surface for rapidly moving the blade downwardly below the work surface responsive to said first actuation signal being received.

52. A table saw as defined in claim 51 wherein the existence of a person at least in close proximity to said sensing mechanism includes a person being in contact with said sensing mechanism.

53. A table saw comprising:

a frame structure with a generally flat work surface;

a rotatable circular blade mounted on an arbor and being adapted to have at least a portion of said blade extending above the flat work surface in position to cut a work piece, said circular blade being electrically isolated from said arbor, a drive motor output shaft and said frame structure work surface, so that an excitation field can be applied to said blade;

a drive motor with an output shaft mounted to the frame structure for powering said blade;

a sensing mechanism for generating at least a first actuation signal responsive to a person contacting said blade;

a pyrotechnic actuator powered retracting mechanism located beneath said work surface for rapidly moving the blade downwardly below the work surface responsive to said first actuation signal being received.