Patents Assigned to Engineered Instruments, Inc.
  • Rock-stress measuring method
    Patent number: 5018389
    Abstract: A method and apparatus of measuring rock-stress uses a tapered sensing plug which is wedged into a conically shaped end portion of a borehole. A rod is used to place the sensing plug in position, to orient the plug relative to its longitudinal axis for sensing stress in a particular direction, and to prestress the sensing plug by causing same to be wedged in the tapered portion of the bore.
    Type: Grant
    Filed: January 9, 1990
    Date of Patent: May 28, 1991
    Assignee: Engineered Instruments, Inc.
    Inventor: Dennis Mraz
  • Anchor device for securing rock bolts
    Patent number: 4976571
    Abstract: An anchor device for securing a rock bolt in a borehole of predetermined diameter includes an elongated plastic cartridge having a first insertable end and a second end, a side wall extending between the ends, and stiffening ribs integrally formed in the sidewall for stiffening the cartridge to permit insertion thereof into the borehole.
    Type: Grant
    Filed: April 6, 1990
    Date of Patent: December 11, 1990
    Assignee: Engineered Instruments, Inc.
    Inventors: Dennis Z. Mraz, Anil Mahyera
  • Anchor device for securing rock bolts
    Patent number: 4820095
    Abstract: Anchor device for securing a rock bolt in a borehole, comprising an elongated cage having a perforated elongated wall confining an elongated chamber containing a bonding means for bonding the rock bolt within the borehole, the cage having a trailing end adapted to mount the anchor device onto the leading end of a rock bolt for insertion into the borehole.
    Type: Grant
    Filed: February 26, 1988
    Date of Patent: April 11, 1989
    Assignee: Engineered Instruments, Inc.
    Inventor: Dennis Mraz