Application Digest

Avoid Damage with Rear-Drive Grippers

By Gary Rosengren, Engineering Manager, Tol-O-Matic

To prevent such damage, engineers can use the new drive-from-behind RotoGripper(TM). It has a fixed gripper housing that allows air lines and a sensor to remain stationary while the gripper jaws rotate free of restrictions. Adjustable stops consisting of polyurethane bumpers limit the gripper's rotational travel.

In any given application each component-the rack-and-pinion rotary actuator as well as the gripper-of the RotoGripper must be sized correctly. Users must choose the proper angular or parallel gripper, keeping load requirements and safety factors in mind.

When specifying a rotary actuator, the user must consider actuator bore size according to its torque requirements and bearing load capacities. If the rotary actuator will physically stop the load, the user must calculate the rotational mass moment of inertia. Next, the kinetic energy per stop must be determined. With this information in hand, the user can decide if standard adjustable stops consisting of polyurethane bumpers can handle the energy. If not, more substantial cushions, or shock absorbers, may be required.

A patent application on the new RotoGripper is currently in process.

To speak to a Tol-O-Matic applications engineer, call:(800)-328-2274.

Laser Triangulation Expands Measurement Options

Robert J. Dwulet, Product Manager, Aromat Corporation

As motion-control and factory-automation systems continue to evolve towards higher performance and cost effectiveness, they depend more and more upon fast, accurate and affordable sensors to measure or profile distance.

Though quick and highly accurate, laser-based interferometers can cost tens of thousands of dollars. In contrast, two-thousand-dollar laser-diode-based sensors represent a powerful dis- tance-measurement alternative whose development and applications are mushrooming.

Laser-diode-based sensors use optical triangulation to measure distance. They offer a number of advantages. For example, low cost (triangulation is a simple calculation), high accuracy and precision (resolutions to 0.2 aemeter), immunity to surface roughness, reflectivity, or color changes, and linearity (as tight as 0.1%).

In addition, the sensors provide a wide operating range-standoff distances from 33 to 250 mm, and flexible system configuration. One- or two-laser systems can be used. Easy calibration, offset, output-error, and zero-point adjustment characterize the laser-diode-based sensors. Furthermore, they offer a versatile interfacing capability. The sensors can be configured to provide raw analog output, GPIB, IEEE 488, RS232C, or 16-bit parallel data, and compatibility with SPC packages. These flexible, versatile devices reduce material waste and save money (which implies a short payback).

To speak with an Aromat applications engineer, call (800) 228-2350.

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