Weighing scales – Self-positioning – Electrical current generating or modifying
Reexamination Certificate
2000-04-06
2001-01-09
Gibson, Randy W. (Department: 2859)
Weighing scales
Self-positioning
Electrical current generating or modifying
C177S229000, C073S862627, C073S862629, C073S862634
Reexamination Certificate
active
06172309
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to strain gage load cells for weighing and force measurement, and especially to an improved design of a shear beam load cell and a new method for making such load cells.
A shear beam load cell comprises a rectangular beam of load cell quality metal alloy, which has one end arranged to be supported on a base in cantilever fashion, and a free end arranged to support a vertical load. Between the supported end and the loaded end there are opposed lateral blind holes forming an I-beam section with a narrow vertical web aligned with the longitudinal axis of the cantilevered beam. Strain gages aligned to measure principal stress due to shear strain are bonded to both sides of the web, and are connected in a bridge circuit for measuring the vertical load applied to the load cell.
Known designs for shear beam load cells can provide high accuracy with low sensitivity to off-center loads, torque and horizontal forces affecting the load application area, so they are widely used in heavy duty weighing applications. The machining of known shear beam load cells requires multiple machining set-ups, however, so the machining cost is a large portion of the cost for such load cells.
SUMMARY OF THE INVENTION
A main objective of the present invention is to provide a high accuracy shear beam load cell which is less costly to make than prior art shear beam load cells.
A further objective of the present invention is to provide an inexpensive shear beam load cell having nearly uniform principal strain due to shear where the strain gages are mounted.
A still further objective of the present invention is to provide a method for machining of shear beam load cells that do not require multiple machining set-ups.
These objectives are obtained by a shear beam load cell wherein both sides of the shear sensing web are cut by a side cutting vertical axle tool with a substantially cylindrical cutting surface, whereby the thickness of the web increases gradually along the axis of the beam.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
REFERENCES:
patent: 3602866 (1971-08-01), Saxl
patent: 4282748 (1981-08-01), Lockery et al.
patent: 4364279 (1982-12-01), Stern et al.
patent: 4506557 (1985-03-01), Jacobson et al.
Flintec Inc.
Gibson Randy W.
LandOfFree
Shear beam load cell and method for making it does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Shear beam load cell and method for making it, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shear beam load cell and method for making it will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2443297