Multiple disk clutch Introduction – Multiple disk clutches are used to deliver extremely high torque in a relatively small space. These clutches can be used dry or wet (oil bath). Running the clutches in an oil bath also greatly increases the heat dissipation capability, which makes them ideally suited for multiple speed gear boxes and machine tool applications. How it works – Multiple disk clutches operate via an electrical actuation but transmit torque mechanically. When current is applied through the clutch coil, the coil becomes an electromagnet and produces magnetic lines of flux. These lines of flux are transferred through the small air gap between the field and the rotor. The rotor portion of the clutch becomes magnetized and sets up a magnetic loop, which attracts both the armature and friction disks. The attraction of the armature compresses (squeezes) the friction disks, transferring the torque from the in inner driver to the out disks. The output disks are connected to a gear, coupling, or pulley via drive cup. The clutch slips until the input and output RPMs are matched. This happens relatively quickly typically (0.2 - 2 sec). When the current is removed from the clutch, the armature is free to turn with the shaft. Springs hold the friction disks away from each other, so there is no contact when the clutch is not engaged, creating a minimal amount of drag. Electromagnetic tooth clutches Electromagnetic tooth clutch Introduction – Of all the electromagnetic clutches, the tooth clutches provide the greatest amount of torque in the smallest overall size. Because torque is transmitted without any slippage, clutches are ideal for multi stage machines where timing is critical such as multi stage printing presses. Sometimes, exact timing needs to be kept, so tooth clutches can be made with a single position option which means that they will only engage at a specific degree mark. They can be used in dry or wet (oil bath) applications, so they are very well suited for gear box type drives. They should not be used in high speed applications or applications that have engagement speeds over 50 rpm otherwise damage to the clutch teeth would occur when trying to engage the clutch. How it works – Electromagnetic tooth clutches operate via an electric actuation but transmit torque mechanically. When current flows through the clutch coil, the coil becomes an electromagnet and produces magnetic lines of flux. This flux is then transferred through the small gap between the field and the rotor. The rotor portion of the clutch becomes magnetized and sets up a magnetic loop, which attracts the armature teeth to the rotor teeth. In most instances, the rotor is consistently rotating with the input (driver). As soon as the clutch armature and rotor are engaged, lock up is 100%. When current is removed from the clutch field, the armature is free to turn with the shaft. Springs hold the armature away from the rotor surface when power is released, creating a small air gap and providing complete disengagement from input to output. Electromagnetic particle clutches Main article: magnetic particle clutch Electromagnetic particle clutch Introduction – Magnetic particle clutches are unique in their design, from other electro-mechanical clutches because of the wide operating torque range available. Like a standard, single face clutch, torque to voltage is almost linear. However, in a magnetic particle clutch torque can be controlled very accurately. This makes these units ideally suited for tension control applications, such as wire winding, foil, film, and tape tension control. Because of their fast response, they can also be used in high cycle application, such as card readers, sorting machines, and labeling equipment. How it works – Magnetic particles (very similar to iron filings) are located in the powder cavity. When current flows through the coil, the magnetic flux that is created tries to bind the particles together, almost like a magnetic particle slush. As the current is increased, the magnetic field builds, st
Posted on: Tue, 15 Jul 2014 13:26:15 +0000
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