Logic control for fast-acting safety system

• US 8,151,675 B2
• Filed: 03/31/2011
• Issued: 04/10/2012
• Est. Priority Date: 08/14/2000
• Status: Expired due to Term

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Gass, Stephen F., Fulmer, J. David, Jensen, Joel F., Schramm, Benjamin B., Chamberlain, Robert L.
• Primary Examiner(s): Alie, Ghassem
• Application Number:
  US13/065,882
• Publication Number:
  US 20110239837A1
• Time in Patent Office: 376 Days
• Field of Search: 83/58, 83/621, 83D/IG.1, 834/771, 834/772, 834/90, 837/88, 834/713, 835/89, 835/81, 833/971, 836/30, 832/92, 197/130, 340/411, 307/117
• US Class Current: 83/58
• 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: B26D 7/24 arranged to disable the operating means for the cutting member
• CPC Class Codes: B27B 13/14 Braking devices specially designed for band sawing machines, e.g. acting after damage of the band saw blade
• CPC Class Codes: B27B 5/38 Devices for braking the circular saw blade or the saw spindle; Devices for damping vibrations of the circular saw blade, e.g. silencing B23D47/005 takes precedence
• CPC Class Codes: B27G 19/00 Safety guards or devices specially adapted for wood saws; Auxiliary devices facilitating proper operation of wood saws
• 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 3/14 the means being photocells or other devices sensitive without mechanical contact
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: Y10S 83/01 Safety devices
• CPC Class Codes: Y10T 83/04 Processes
• 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 83/148 Including means to correct the sensed operation
• CPC Class Codes: Y10T 83/707 By endless band or chain knife
• CPC Class Codes: Y10T 83/7726 By movement of the tool
• CPC Class Codes: Y10T 83/773 Work-support includes passageway for tool [e.g., slotted table]
• CPC Class Codes: Y10T 83/7788 Tool carrier oscillated or rotated

Abstract

Woodworking machines including cutting tools and motors adapted to drive the cutting tools are disclosed. The machines also include a detection system adapted to detect a dangerous condition between the cutting tool and a person, and a reaction system adapted to perform a specified action upon detection of the dangerous condition. The machines further include a control system adapted to test the operability of at least a portion of the detection system and/or the reaction system. The control system is adapted to disable the motor if the tested portion is inoperable.

Claims

1. A woodworking machine comprising:

a support structure;

a cutting tool adapted to move to cut a workpiece, where the cutting tool is supported by the support structure;

a motor adapted to drive the cutting tool;

a detection system adapted to detect a dangerous condition between the cutting tool and a person, where the detection system imparts an electrical signal to the cutting tool and monitors one or more characteristics associated with the electrical signal for changes indicative of the dangerous condition;

a reaction system adapted to perform a specified action upon detection of the dangerous condition; and

a self-test system adapted to test the operability of at least a portion of the detection system and the reaction system, and to disable the motor if the tested portion of the detection system or the reaction system is inoperable.

2. The machine of claim 1, where the detection system includes at least one charge plate operatively associated with the cutting tool, where the self-test system is configured to detect a predetermined signal on the charge plate, and where the motor is not actuated unless the predetermined signal is detected.