friction clutches - Arten Freios e Embreagens Industriais

Table of Contents◗APPLICATION GUIDETension MeterOften you need to only measurethe tension in a web, not controlit. Nexen has a variety of solutionsto meet these needs.Web ProductsTENSION METERS AND AMPLIFIERSTension MeterNexen tension meters preciselymeasure web tensions with adigital tension display on thefront panel. Their 0-10 VDC or4-20 mA analog output is alsowell suited as a proportional tensiondata signal to process controllers,data loggers and variable-speedmotor controls.You can also use one of thesensors for narrow webs, singlestrands of wire, or any other narrowmaterial where tension will notvary from one side to the other.Nexen tension meters are alsouseful as a tension readout-onlydevice to measure intermediatezonetension.Tension AmplifiersNexen tension amplifiers interfacewith load cell or straingauge sensors. They provide anexcitation signal to the sensorsand separately amplify the returnsignal from each sensor beforecombining them to provide asignal proportional to the totaltension.Tension amplifiers are ideal foraccurate, low-cost tensionmeasurement of a web processinterfaced with machine controlssuch as data loggers, processcontrollers, drive controls, hostcomputers and other applicationsrequiring a precise tensioninterface.Tension Amplifiers Offer:• Low cost signal conditioningfor LVDT or strain gaugetension sensors• Wide tension range forflexible installation• Ideal for use with machinecontrols where localreadout is not required• Includes both 0-10 VDCand 4-20 mA outputsControlled lateral alignment of the web isabsolutely essential to providing high qualityproduct and reducing scrap and waste.Nexen web guiding systems are designed,tested and proven to give you that alignmentWeb Guiding ApplicationsWEB GUIDING SYSTEMSUnwind Guiding (See Figure 1)As material is unwound and fed into amachine, it must be properly aligned with theprocess to be performed upon it.Unwind guiding is accomplished by sensingthe web as it enters the machine. The sensoris mounted as part of the main machineframe and placed so that its center is locatedat the desired position of the web. Thecontroller directs movement of the actuator,which moves the roll stand laterally acrossthe machine to bring the edge of the roll intothe center of the sensor.Intermediate GuidingThis method is normally used in the intermediatezone to make minor corrections inposition. The steering rolls pivot, directingthe web to the left or right to bring it intocenter position within the sensor.26Displacement Guides (See Figure 2)Displacement guides consist of a pair ofpivoting rollers with a pair of stationery idlerollers, one lead-in roller before the guideand a lead-out roller after the guide. Thistype of guide induces pure, out-of-planetwisting of the web, which is gentler on aweb than a steering guide. Much shorterfree spans are required before and afterguiding when compared to a steering guide.Displacement guides are often used onprinting presses and other applicationswhere space is at a premium.Windup Guiding (See Figure 3)The position of the web is monitored by asensor mounted on the moveable windup rollstand, positioned before the last roll on themachine. As the web shifts laterally, thecontroller signals the actuator to move thewindup roll into line with the web edge.Chase GuidingChase guiding is a technique used to alignthe edge of two or more webs or to align aprocess to a web. The sensor is moved bythe actuator to “chase” the edge of the web.In the case of aligning several web edges,the sensors for the second and subsequentwebs are aligned with the chase sensor andmove in tandem with it. This moves the targetor center of the sensor for allsubsequent webs, which in turn causes theguides to align their webs to the target.To align the process to the web, the sensoris mounted to the moveable processcomponent. The actuator then moves thecomponent, causing the sensor to chase theweb edge or printed line.