Apparatus and method for detecting dangerous conditions in power equipment

• US 7,644,645 B2
• Filed: 11/17/2008
• Issued: 01/12/2010
• Est. Priority Date: 01/16/2002
• Status: Expired due to Term

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Huebner, Randall J., Fanning, David A., Gass, Stephen F., Fulmer, J. David
• Primary Examiner(s): Alie; Ghassem
• Application Number:
  US12/313,277
• Publication Number:
  US 20090133555A1
• Time in Patent Office: 421 Days
• Field of Search: 83/621, 83/58, 834/713, 834/90, 834/771, 835/89, 835/81, 833/97, 833/971, 834/77, 83D/IG.1, 836/30, 832/97, 836/44, 83/74, 83/761, 83/767, 834/772, 324/678, 324/659, 324/686, 324/660, 324/725, 324/706, 303/88, 302/76, 302/774
• US Class Current: 83/62.1
• 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: B23Q 11/0082 by determining whether the operator is in a dangerous position B23Q17/2438 takes precedence
• CPC Class Codes: B23Q 11/0092 actuating braking or stopping means
• CPC Class Codes: B23Q 11/06 Safety devices for circular cutters
• CPC Class Codes: B23Q 17/2438 of an operator or a part thereof
• 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: 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: Y10S 83/01 Safety devices
• 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 83/162 With control means responsive to replaceable or selectable information program
• CPC Class Codes: Y10T 83/175 With condition sensor
• CPC Class Codes: Y10T 83/768 Rotatable disc tool pair or tool and carrier
• 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

A machine such as a saw, jointer, planer, etc. is disclosed. The machine has cutting tool, a direct drive mechanism configured to move the cutting tool, a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, and a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system. An electrical signal is imparted on the cutting tool, and the signal is used to determine the occurrence of the unsafe condition. The direct drive mechanism is electrically isolated so that the electric signal may be imparted on the cutting tool. The electric isolation may be achieved through configurations such as insulated bearings, a substantially non-conductive housing, and a substantially non-conductive coupling joining two shaft portions.

Claims

1. A saw comprising:

a circular cutting tool, where the cutting tool is adapted to spin;

a rotatable arbor of conductive material configured to support the cutting tool;

at least one bearing supporting the arbor;

an insulating surface positioned and configured so that there is no electrically conductive path from the arbor to ground through the bearing;

a motor configured to spin the arbor, where the motor includes an electrically grounded drive shaft;

a gear train interconnecting the drive shaft and the arbor without a belt, where the gear train includes at least a first gear driven by the drive shaft, a second gear configured to drive the arbor, and a non-conductive contact surface positioned and configured so there is no electrically conductive path from the arbor to the drive shaft through the gear train;

a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, where the detection system is adapted to impart an electrical signal on the cutting tool; and

a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system.

2. The saw of claim 1, where the gear train includes a coupling connecting the drive shaft and the first gear, and where the non-conductive contact surface is part of the coupling.

3. The saw of claim 1, where the gear train includes a coupling connecting the arbor and the second gear, and where the non-conductive contact surface is part of the coupling.

4. The saw of claim 1, where the non-conductive contact surface is part of the first gear.

5. The saw of claim 1, where the non-conductive contact surface is part of the second gear.

6. The saw of claim 1, where the gear train includes a spacer and where the non-conductive contact surface is part of the spacer.

7. The saw of claim 1, where the gear train includes a planetary gear and where the non-conductive contact surface is part of the planetary gear.

8. The saw of claim 1, where the gear train includes an eccentric portion and where the non-conductive contact surface is associated with the eccentric portion.

9. The saw of claim 8, further comprising a sleeve configured to engage the eccentric portion and where the non-conductive contact surface is part of the sleeve.