Streamlining Die Changeovers: Focusing on Efficiency and Safety

With the majority of the groundwork already laid for efficient die changeovers, the focus now shifts to further eliminating wasted time from the process. At the sprawling 650,000-sq.-ft. Rheem Water Heating plant in Montgomery, AL, significant strides have been made through a quick die change (QDC) program, particularly benefiting die setters working on the plant's largest mechanical presses.

Previously, setters at these presses grappled with cumbersome tasks, manually aligning dies weighing up to 20,000 lb. using pry bars. This meticulous process of inching the ram down and manually adjusting the die for accurate alignment was both time-consuming and labor-intensive.

The capital improvements implemented in early 2010 were centered around enhancing QDC, primarily by introducing roller-type hydraulic lifters to facilitate the movement of die sets. Dies now effortlessly roll in beneath fixed, mounted wedge clamps installed on the press bed. Once the die lifters are lowered, the bed clamps are pressurized with the simple flip of a switch. Subsequently, the upper hollow piston clamps advance into position via pneumatic traveling clamps. Proximity sensors meticulously monitor the extend and retract positions of the air cylinders. Upon reaching the desired position, the clamps are pressurized, with additional safeguards in place such as a slide-mounted connection block that establishes dual diagonal clamp circuits for added security and stability.

Hilma supplied all of the quick die change (QDC) equipment, which encompassed an air-hydraulic power unit along with pressure switches integrated into each clamp circuit. These switches play a critical role in providing feedback to ensure that the press operates only when full operating pressure is readily available. Additionally, the die-lifter circuit incorporates a relief valve designed to divert pressure back to the oil reservoir in the event of overloading of the rollblocks. This comprehensive setup not only enhances the efficiency and safety of the die change process but also safeguards against potential operational disruptions and equipment damage.

“As the two 550-ton presses already had quick-change clamps on their rams, most of the recent work for this project was done on the 400-ton press,“ recalls Krauss. “We fabricated a 3-in. ram plate, cut wire/utility pathways into the plate and fabricated covers for it, so we’re able to run all of the sensor and air cables out to minimize the footprint. The alternative would have been to use swing clamps on the outside, to keep the utilities out of the way. However, using hollow piston travelling advance clamps proved to be a less-expensive and more-effective solution.”

The Hilma QDC package includes a ready-made control panel that ties in the valve manifold, pressure switches, actuation switches and the run circuit. “If we lose any of the pressure switches,” Krauss says, “it kills power to the flywheel, preventing the press from stroking.”