Part Presence Sensing on a vibratory conveyor?


Thread Starter

John Kelley

I am working on a pilot project for a large foundry concern. The organization has vibratory conveyors (shakers) that move molded metal castings down a line and shake off molding sand and excess material.

Part of this process also cools the castings for processing and some plants are looking to decrease cooling times on larger parts. We recently installed zones of time controlled water sprayers for this purpose.

While the desired cooling effect was achieved, it presented a new problem. Castings do not move through the system at a precise rate, so that sometimes the sprayers come on with no parts underneath. As you can imagine, on a conveyor filled with sand this creates a muddy mess on the shaker bed.

I thought perhaps someone might know of a sensor package ie ultrasonic, IR or laser that would see parts on the shaker bed and turn sprayers on. A standard photoelectro might work if I can get a large enough sensing footprint, or perhaps a temperature differential in the sensing field makes more sense.

On a recent day's measurement, I detected (with a handheld IR thermo) the shaker bed at about 100 deg. F and the part at 550 deg. F. Stationary IR's will not work without a wide beam pattern as the shaker bed is about 4 feet wide and I need to see completely across it, preferably with a 4 x 4 footprint. As this is a dirty environment, the sensor would have to be some feet away from the conveyor.

I also thought about measuring the heat on the shaker bed but was concerned about how a sensor would hold up in such a application. It might also be fairly inaccurate as the sensor would have to be mounted underneath the conveyor's bed and a great deal of heat sinking from part-to bed- to underneath will likely take place.

I don't care about precise measurment and will likely use a standard discrete input to turn the sprayers off and on (or at least initiate a timed cycle).

Any help gladly accepted... I don't have a hugh budget on this project so I need to be as creative as possible.



Richard Norris

You may want to consider a fibre optic sensor. I am aware of the Banner range with glass fibres rated as high as 900°F. Hope this is of help

Richard Norris

Any of a wide assortment of security sensors can do what you've described. There are "request to exit" sensors that open doors when a person enters the zone, passive infra-red (PIR) sensors that detect moving warm bodies, active infra-red sensors (photoelectric eye) which detect beam interruption and presence sensors which strangely enough detect the presence
of an item in the sensing zone to prevent doors from closing on people, etc.

Several good companies make these things, including Optex, Aritech, ADEMCO, DSC and Sentrol just to rattle off a few names. Both indoor and
outdoor models are available, and they operate at ranges from a few feet to several hundred. Most expensive line is the active infra-red since most
require a transmitter and a receiver, all others can be had for less than $100. Many operate on 8-30 volts AC/DC and provide a form C relay output.

Carl Ramer, Engineer
Controls & Protective Systems Design
Space Gateway Support, Inc.
Kennedy Space Center, Florida

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