Transicoil pressure transducers convert mechanical energy into an electrical signal. When pressure is applied, the element's motion is transmitted to the ferro-magnetic core of a linear variable differential transformer, or LVDT. The electrical signal from the LVDT is processed by internal electronics to show the pressure condition. The diaphragm pressure sensors used in the company's transducers were subject to permanent deformation in overpressure conditions, requiring replacement and resulting in expensive downtime.

High-durability transducers equipped with bellows sensors from Servometer Corp. provide up to 35 times the overpressure tolerance of transducers equipped with capsule assemblies.

To solve this problem, the company decided to replace its diaphragm sensors with bellows sensors, supplied by Servometer Corp. of Cedar Grove, N.J. The tube-like bellows sensor resists mechanical deflection much better than the thin-plate diaphragm sensor, according to Servometer engineer Paul Hazlett. Bellows sensors offer better resistance to deformation in overpressure, according to Servometer Corp. The bellows component is manufactured in an electro-deposition process that provides tight control over wall thickness, high chemical purity, and good retention of mechanical properties.

The conventional mechanical sensing element is called a capsule assembly. It consists of hemispherical diaphragm elements welded together to form a hollow chamber. The usual material is NiSpan-C, a nickel-based alloy. Pressure peaks beyond the 1.5 times rated margin will cause a dent or bubble in the spherical body of the capsule assembly. Once deformed, it is out of calibration and the transducer needs to be replaced. Replacing a damaged conventional transducer usually means shutting down a process, to remove the broken transducer and install a new one. This downtime can be expensive. Also, because the pressure sensor has failed, there is no easy way to trace the cause of overpressure. The new transducer may fail again.

Transicoil partnered with Servometer to come up with a solution involving a precision metal bellows designed for high overpressure applications. Transicoil tested its standard industrial pressure transducers equipped with bellows sensors to withstand overpressures of about 35 times the rated measurement range—far higher than the 1.5 times provided by the capsule assemblies.

Transicoil also designed the bellows component into its wide zero/span D/P pressure transducer. In this product, the range of pressure measurement can be adjusted to move the zero value to different parts of the rated range, allowing the transducer to be placed in a more convenient site. Or the calibrated range or span can be compressed from 100 percent to 10 percent of the rated range, providing higher overpressure capability at a lower pressure range. The precision metal bellows' high overpressure capability provides similar protection with this product.

Servometer manufactures the bellows component by forming a mandrel to the shape of its inside surface, and then depositing a defined thickness of spring-quality nickel onto the mandrel. The plated material is trimmed to define the ends; then the mandrel is removed by dissolving it. This leaves behind a thin, convoluted tubular shell of plated metal, which is the bellows.

Wall thickness of the bellows components fabricated for Transicoil ranges from 0.0015 to 0.006 inch.

The static VAR system will be installed to serve the arc furnaces in the mill's melt shop. These furnaces will melt scrap steel that will be cast to produce structural steel. The control system will minimize the power factor—that is, the ratio between the active power and the reactive power of the furnace—and stabilize the voltage, thereby maximizing the input power to the furnace while reducing unwanted voltage flicker and harmonic voltage distortion.

After Alstom installs the system at the mill, its engineers will remain on site for fine-tuning to ensure that all is working properly. The contract specifications for the new system include maintenance of a voltage flicker level of less than 0.4 percent, and a total harmonic voltage distortion not greater than 1 percent at the point of common coupling.

The Columbia City installation will be the third static VAR control system Alstom has supplied to Steel Dynamics' facilities. This mill is located about 20 miles from the SDI steel plant in Butler, Ind., home to two similar systems Alstom installed in 1995. The successful track record those systems established convinced Steel Dynamics to seek Alstom's voltage stabilization equipment when building its Columbia City plant.

The SLS-6000 laser sensor is being used by a tire producer in the Southeast to measure hot melted green rubber as it comes off the extruder.

To improve inspection and production control, the company has developed a new noncontact, laser-based industrial gauging sensor for measuring rubber and tire extrusions. The SLS 6000 sensor has a standoff of 15.75 inches with a 1.97 measurement range, and can be used in high-speed applications. This is a significantly longer range than the company's other laser sensors for rubber and tire applications, according to LMI Selcom engineer Dan Howe. LMI says that its SLS 6000 sensor is currently being used in a tire plant in the southeastern United States to measure melted rubber as it comes from an extruder.

The SLS 6000 is available as a Class II or Class III sensor. Howe said that Class III is probably better suited for hot rubber applications, because of its stronger signal. Class II and III ratings differ in their safety precautions.

The SLS 6000 sensor is specialized for green rubber extrusion measurement and for thread wear analysis, both on- and offline. Other applications include profiling green rubber, sidewall bulge and dent, splice width, and radial run-out, or the "out-of-roundness," of a tire. The standoff allows the sensor to be placed away from workspace and other equipment. A flat lens and an internal air purge cool the unit and keep vapors from clouding the lens.

The SLS 6000 has a built-in signal processor for data averaging and filtering, insensitivity to light, surface texture, or plant conditions, and sampling frequency within a very defined spot. The sensor has an accuracy of plus or minus 0.02 inch and resolution of plus or minus 0.005 inch. It has a data sampling rate of 16 kHz and a response of 2 kHz. It is built to NEMA-4 standards and is enclosed in aluminum housing.

The NC1 system uses a compact, laser-based transmitter to send a beam to the receiver unit. System electronics detect when a tool breaks the beam, and output signals are sent to the machine's controller, allowing the position of tips, teeth, or cutting edges to be established.

The NC1 noncontact, laser-based toolsetting system from Renishaw detects broken tools on the fly, avoiding costly rework.

On the NC1, setting of both length and diameter is carried out at normal spindle cutting speeds, allowing errors caused by radial run-out of the tool and the tool holder to be identified and corrected.

The NC1 laser-based toolsetting system can measure tools anywhere along the laser beam, up to 2 meters in length, minimizing cycle times for broken tool detection, according to Renishaw. Tools as small as 0.008 inch diameter can be measured, with system resolution of 0.00004 inch. Noncontact measurement ensures that coatings on the tooling are not damaged.

A tool can pass at rapid traverse rates through the beam at the nearest point to reduce machine movements and save time.

Typical cycles include static length setting of tools, rotating length setting of tools such as face mills, and rotating diameter setting of slot drills and boring bars. The machine's software allows each facet of a multifaceted tool to be checked and includes thermal compensation for changes in machine temperature.

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