Hottinger Baldwin Messtechnik Gmbh

Hottinger Baldwin Measurements Inc.

Werner Julius Ort

A force that causes tensile stress in a thread must be measured, for example in the textile industry, to avoid overstretching of the thread. Thus, small thread tensions must be maintained for many threads moving at high speeds. For this purpose a device for measuring thread tensions up to about 0.1 N (Newton) has a rod type metal component, one end of which forms a mounting member while the other end forms a thread engaging lever arm connected to the mounting member by a flat leaf spring carrying at least one strain gage. The lever arm is, e.g., conically tapering away from the leaf spring and carrying a thread engaging cylinder or extension at its end remote from the leaf spring. The signal provided by the strain gage is proportional to the force. The device forms a thread tension sensor having an eigenfrequency of about 3 kHz for measuring tensile stress on threads travelling at high speeds.

Device for measuring a force causing tensile stress in a thread

A strain gage or a measuring transducer equipped with such a strain gage has, for supporting the measuring grid structure, a backing made of a polyphenylenesulfide film. Such a backing assures a plurality of desirable characteristics simultaneously and equally well for each characteristic.

Strain gage, transducer employing the strain gage, and method for

A strain gage transducer or rather a large group of such transducers is balanced by a combination of at least one balancing resistor embedded in an insulating member and connected in a corner of a bridge circuit formed by the strain gages, and a number of adjustment resistors included in a flat, flexible printed circuit type cable having first conductor strips connected at one inner end to said balancing resistor in the embedding insulating member and electrically interconnected at the other output end. The adjustment resistors form part of the flat first conductor strips and are initially short-circuited by respective conductor strip sections which are interrupted for the adjustment.

Strain gage transducer

A strain gage transducer, preferably of the above double bending spring or beam type, has secured to its spring or springs strain gage elements etched out of foil from which further conductor configurations have been simultaneously etched. These further conductor configurations are shunted by interruptable short circuits. Some of these configurations have such a shape that they are substantially nonsensitive to strain and hence located in a zone or zones of the spring or beam where the deformation due to strain is relatively small, for example in a central zone. Others of these configurations have a shape to exhibit large creeping. The latter shapes and the respective strain gage elements are secured to the spring or springs substantially in zones of large deformation. By interrupting the proper short circuits the negative creeping of the foil strain gage compensates the positive creeping of the respective spring.

Strain gage transducer with a foil strain gage arrangement secured to a

A foil strain gauge pick-up is protected against environmental adverse influences by a multi-layer covering hermetically sealing and enclosing substantially the entire pick-up including its terminals. The covering includes at least two layers, preferably three layers. The first layer adjacent to the foil strain gauge proper is an electrically insulating layer. The outer layer may be a vapor deposited metal or oxide layer. An intermediate layer may be electrically conducting.

Method and apparatus for covering a foil strain gauge

In a mechanical to electrical transducer, a plurality of strain gauges are mounted either on a diaphragm or on a flexure spring mechanically coupled to the diaphragm. The diaphragm is mounted on a clamping ring, and the strain gauges are disposed at different distances from the clamping ring. In order to equalize the heat transfer of the strain gauges with respect to the clamping ring, the areas of the strain gauges may be varied, the spacings of the conductors of the strain gauges may be varied, the relative positioning of the strain gauges may be controlled, the width of various portions of the flexure spring may be varied, or slots may be provided adjacent certain strain gauges in the flexure spring.

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Darmstadt, Germany

Werner Julius Ort