AUTOMATIC SAFETY BRAKE FOR ROTARY BLADE EQUIPMENT

• US 3,785,230 A
• Filed: 11/08/1972
• Issued: 01/15/1974
• Est. Priority Date: 11/08/1972
• Status: Expired due to Term

• Current Assignee: Robert C. Lokey
• Original Assignee: Robert C. Lokey
• Inventors: Lokey, Robert C.
• Primary Examiner(s): Schran, Donald R.
• Application Number:
  US05/304,726
• Time in Patent Office: 433 Days
• Field of Search: 408/710 82/34R 30/390,388,391 83/72,544,571,860,58 192/129R,129A,130,131,144 317/DIG.2
• US Class Current: 30/388
• CPC Class Codes: B23Q 11/0092 actuating braking or stopping means
• CPC Class Codes: B23Q 11/08 Protective coverings for parts of machine tools; Splash guards
• 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 3/148 using capacitive technology
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means

Abstract

An automatic safety brake for rotary blade equipment in which a capacitance proximity sensor utilizes the spinning blade as an antenna so that when any portion of the body of the user approaches the blade to closely a cam brake will be instantaneously actuated to stop the rotation of the blade before the body of the user comes in contact with the cutting edge of the blade. In one form of the invention cam members are applied to opposite side faces of the blade to serve as a brake for the instanteous stopping of the rotation of the blade. In another form of the invention a rubber wedge is driven into the cutting edge of the blade so as to instantaneously stop the rotation of the blade. In both forms of the invention the sensitivity of the sensor may be adjusted to suit the capacitance effect of the individual user of the equipment.

Claims

1. A power tool comprising a frame, a rotating cutting blade mounted in said frame, a brake mounted in said frame for movement into blade contacting position, a solenoid mounted in said frame and connected to said brake for moving said brake into contact with said blade, a capacitance proximity sensor mounted on said frame for detecting the approach of a portion of a human body to said blade, and means actuated by said sensor for energizing said solenoid to instanteously stop said blade when a portion of the human body closely approaches said blade.

2. A device as claimed in claim 1 including means for adjusting the relative senitivity of said sensor to tune said sensor to the capacitances of the body of the user.

3. A device as claimed in claim 1 wherein an audible signal is actuated by the means for actuating said solenoid prior to the actuation of said solenoid.

4. A device as claimed in claim 1 wherein said brake is mounted for rotation and includes a cam surface for binding engagment with the side face of said saw blade.

5. A device as claimed in claim 1 wherein said brake is mounted for sliding movement with respect to said blade and engages the cutting edge of said blade.