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Force Displacement Measurement Apparatus

IP.com Disclosure Number: IPCOM000083589D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 86K

Publishing Venue

IBM

Related People

Foytlin, LF: AUTHOR

Abstract

Figs. 1A through 1C show sequential positions in the operation of a force-displacement apparatus. The apparatus is designed to measure the force required to actuate a key module, and to measure the distance or displacement between the retracted position of the module and the actuated position.

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Force Displacement Measurement Apparatus

Figs. 1A through 1C show sequential positions in the operation of a force- displacement apparatus. The apparatus is designed to measure the force required to actuate a key module, and to measure the distance or displacement between the retracted position of the module and the actuated position.

In Fig. 1A, the apparatus is shown with the actuating push rod 1 positioned vertically over a key module 2. Push rod 1 is confined to move in a vertical direction by guides 3, which have lubricated free-bearing surfaces to eliminate friction between the guides and the push rod. Push rod 1 is an integral part of a commercially available spring scale 4.

Spring scale 4 has a spring 5, a barrel 6 (shown broken away for clarity in showing the internal parts), a pointer 7, and a force scale 8. If the push rod 1 is pulled in the upward direction and the barrel 6 is held fixed, the pointer 7 will move up scale 8. Similarly, if motion of the push rod 1 in the downward direction is resisted by contact with the key module 2 and the barrel 6 is driven downward, pointer 7 will move up scale 8.

Pointer 7 is firmly affixed to the push rod 1 and is also the buttress or stop member to which spring 5 is attached, the opposite end of spring 5 being attached to the end slug 9 in barrel 6. Barrel 6 is driven up and down by rotating cam lobe 10 affixed to a continuously rotating drive shaft 11, which is part of a motor mounted to a main framework, not shown.

Cam 10 rotates in the direction of the arrow shown and bears against a driving plate 12 which is affixed to barrel 6 of scale 4. Driving plate 12 is also held in contact with cam 10 by a tension spring 13 which is affixed to the framework
14.

The push rod 1 has a clamp 15 affixed to it by a screw 16 which serves two purposes. First, clamp 15 positions the barrel 6 of scale 4 relative to push rod 1, so that a preload of a given amount of force may be introduced by locking the push rod 1 and scale 8 with a certain extension in spring 5. Secondly, the clamp 15 holds a gear rack 17 which engages a pinion 18 for rotation whenever the push rod 1, together with clamp 15, is moved relative to the barrel of scale 4.

Pinion 18 is operated through a unidirectional clutch, so that pinion 18 will only be driven when push rod 1 moves down with relation to the barrel 6 of scale
4. This action will move rack 17 down and drive pinion 18 in the counterclockwise direction. A needle 19 is affixed to pinion 18 to indicate on a scale, the amount of displacement whi...