Conveyor Oven Designed for Stress Relief on Locking Wheel Hubs

Dec 17, 2007

Wisconsin Oven designed and manufactured an Electrically Heated Conveyor oven to perform stress relief on locking wheel hubs at a maximum production rate of 600 pounds of parts per hour. The oven is designed to heat parts from 70° F to 1,100° F. The oven has a 30” wide x 9’ long x 1’ high heating chamber and a 1,250°F maximum operating temperature.

The equipment is “can” constructed with 10” thick insulation, 3/16” thick plate steel exterior (1/2” thick plate steel oven fronts), and 16 gauge 304 stainless steel interior. The ductwork is fabricated of 18 gauge 304 stainless steel.

The heating system is rated for 180 kW of heat input and features plug mounted incoloy sheathed tubular heating elements with Zero-Fired SCR power control. The recirculation blower is rated for 18,000 CFM at 15 HP and provides bottom-up airflow.

The uniformity test was performed with three (3) thermocouple points buried in a 3” deep layer of parts. Each point was buried approximately 1-1/2” deep from the top side of the conveyor belt. The customer required a part temperature uniformity of +/-10° F at 1,080° F for a minimum of 30 minutes with a 90 minute total heating time inside the chamber and a normal conveyor speed of 1.2 inches per minute. The oven maintained the required uniformity for 48 minutes. 

The conveyor features a self supporting chain-edge design and a 304 stainless steel wire mesh belt with 3-1/2” high 304 stainless steel shingle side plates to contain the parts. The system featured a chain driven gear reducer, closed loop control of the conveyor speed which utilized a pulse counter, and an analog converter. The conveyor speed was displayed and could be adjusted from a Honeywell UDC 2500 controller mounted on the control panel door and is set up to sound an alarm if the conveyor is unable to maintain the required pre-set speed range. The exit end of the conveyor was designed to allow the customer’s part bins to be accurately placed and picked up with a fork truck into a position that allowed the parts to drop directly into the bin from the conveyor belt (a steel “bumper” is utilized to protect the conveyor belt from damage and allow the fork truck operators to quickly drop and pick up part bins). A three light stack light was implemented into the system with three (3) different colors assigned to particular alarms. Three conveyor E-stops were also provided with the oven.

The UL labeled and certified NEMA 12 control enclosure includes an Allen-Bradley Powerflex 4 variable frequency drive with electronic torque limiting, and a main power fused disconnect switch. The controls feature IEC style push buttons and pilot lights. The temperature was controlled by a Honeywell UDC 2500 temperature controller and over temperature protection was also provided by a UDC 2500 controller. An automatic shutdown feature with a separate stack light was also included.

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