Shear tester
Inventors
Assignees
Publication Number
US-11243150-B2
Publication Date
2022-02-08
Expiration Date
2040-02-18
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Abstract
A portable shear testing device includes a shear force unit that has two elongated jaw members that are positioned adjacent to each other. One of the jaw members can be moved away from the other, stationary jaw member. One of the jaw members is moved by a pivotally mounted lever that laterally moves a load transfer block connected to the jaw member. A digital load cell is positioned between the lever and the load transfer block and a threaded knob is rotated to press against the lever.
Core Innovation
The invention is a portable shear testing device that includes a shear force unit having two elongated jaw members positioned adjacent to each other, with one jaw member movable away from the other stationary jaw member. The movable jaw is actuated by a pivotally mounted lever which laterally moves a load transfer block connected to the jaw member. A digital load cell is interposed between the lever and the load transfer block, allowing measurement of the force applied. A threaded knob is rotated to press against the lever, thereby controlling the movement and force application.
The device addresses drawbacks in existing portable shear testing devices, which often utilize pneumatic pressure sensors requiring cross reference sheets for interpretation and typically have multiple moving parts and high internal friction, leading to reduced measurement accuracy. The present invention improves usability and accuracy by employing a mechanical lever mechanism coupled with a digital load cell and a bearing-supported load transfer system.
An additional embodiment includes a drill guide assembly that fits within a baseplate having key portions for aligned engagement. The drill guide includes a drill bit configured to cut a circular groove in a material, facilitating the creation of samples with defined circular edges for shear testing by the jaws of the shear testing device. This integration allows precise preparation of test specimens alongside the shear testing device's use.
Claims Coverage
The patent includes two independent claims describing other various inventive features of the portable shear testing device and a method of use. The following inventive features are disclosed:
Portable shear testing device with load transfer via pivotally mounted lever
A portable shear testing device including a housing on a base plate, a top bearing block disposed on a bottom bearing block configured to move longitudinally within the housing, a digital load cell connected to the top bearing block, first and second elongated jaw members where the first is movable and connected to the top bearing block, the second stationary, and a lever pivotally mounted within the housing applying variable pressure on the digital load cell according to lever position.
Threaded knob to actuate lever position
A knob having a threaded portion configured to screw into the housing to move the position of the lever, thereby controlling the applied force and jaw movement.
Bearing block system reducing friction for load transfer
Top bearing block includes a plurality of bearings in a groove allowing movement over a shaped bottom bearing block to reduce friction and support the load transfer block facilitating precise lateral jaw movement.
Pressure sensing display connected to digital load cell
Pressure sensing device located outside of the housing connected to the digital load cell to display real-time force readings applied by the jaws.
Drill guide and guide plate system for creating circular grooves
A drill guide assembly with a drill shaft and bit configured to cut circular grooves and a guide plate with mating key shapes to precisely align the drill guide for reproducible groove cutting.
Method of shear testing with circular groove preparation
A method comprising positioning a drill guide to create a circular groove in a first material exposing a second material beneath, placing the shear testing device near the groove with jaws contacting the groove sides, actuating the device to move the jaws apart applying shear force, and displaying a measurement from the load sensor.
The claims cover a portable shear testing device featuring a pivotally mounted lever actuated by a threaded knob to move a load transfer block supported by bearing blocks with a digital load cell for force measurement, supplemented by a drill guide system for preparing test samples and a method for conducting shear tests using this apparatus.
Stated Advantages
Improved usability over current portable shear testers by avoiding pneumatic pressure sensors and difficult-to-interpret readings.
Reduced internal friction and fewer moving parts enhance measurement accuracy.
Integration of a digital load cell provides direct and clear force measurement.
The drill guide and baseplate allow precise preparation of test specimens facilitating effective shear testing.
Documented Applications
Shear testing layered materials such as metal, plastic, ceramic, composites, adhesives, and glued assemblies.
Confirming proper adhesion of tile panels to underlying structural components, for example, aluminum-to-aluminum or aluminum-to-composite bonds via epoxy.
Creating circular grooves in a top material adhered to a second underlying material to prepare a test specimen for shear strength evaluation.
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