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Shaping Excellence: The Role of Grotnes’ Expanders in Washer and Dryer Drum Manufacturing

A leader in metal-forming technology, Grotnes offers a suite of machines designed to produce washer and dryer drums with precise results. Our state-of-the-art shrinking, expanding and roll-forming machines are at the heart of production for several industry-leading manufacturers, transforming raw materials into top-tier components with unparalleled accuracy.


Expanders shape metal to exact dimensions with segmented tooling

Baffle hole punchers create clear-cut openings for auxiliary attachments

Belt groovers form seamless channels

Drum body formers perform the final sizing for tolerance and shape

• The function of hemmers/curlers is to ensure a smooth, safe edge for both aesthetics and function

Flangers and seamers round out the process, adding the necessary curves and joints to produce a drum that meets industry standards

In this blog post, we’ll detail two of our expanders, explaining how they work and what customers can expect from Grotnes during the acquisition process and post-installation.


#8-HE-60-16 Expander


Grotnes’ hydraulically operated expander, a self-contained, floor-mounted unit, is engineered for seamless integration into a user’s facility. This system is comprised of the hydraulic pump unit (HPU), the expander and an operational pendant.


The machine utilizes a two-piece “clamshell” outer assembly to accurately position the part atop the expander, which also secures the necessary external tooling. The jaws of the machine are arranged to maintain a gap at the top for weld relief purposes.


Central to the expander’s mechanism is a durable alloy steel cone, precision-machined with flat bearing surfaces. Surrounding this are steel jaws outfitted with wear plates, gliding against the cone’s surface. A table with milled slots underpins and guides these jaws, while the gibs affixed to the table prevent axial movement, ensuring consistent contact with the cone. A hydraulic cylinder exerts the necessary force, with the expander’s operation alternating between two speeds for efficient material expansion and retraction.


The Human-Machine Interface (HMI) offers the functionality to craft and store part programs, incorporating variables such as starting, slowdown and target diameters to manipulate the machine’s forming process. This system also boasts a gauging feature for measuring the final diameter post-expansion. With user-friendly interfaces, the HMI offers an intuitive platform for overseeing and adjusting several machine functions.


How the#8-HE-60-16 Expander Works


During production, the operator ensures the correct tooling is installed and the appropriate program is selected in automatic mode. They begin the expansion process by pressing the appropriate cycle-start button. The machine, equipped with precise tooling, then automatically expands the product to the desired diameter, shaping it with the inner and outer dies. Upon completion of the cycle, with the machine idle at start position, the operator removes the part. If the light curtain is breached during operation, the machine halts and maintains its position until the obstruction is cleared and the operator restarts the cycle via the pendant.


Rotating Gapless Expander Model #5-2-RHE-35-12


Like the #8-HE-60-16 Expander, this standalone unit is essential for final forming and roll forming. It encompasses three main interconnected components: the expander, the hydraulic pump unit with a control cabinet and an operator pendant; the layout of these components is confirmed during a technical review prior to installation.


The expander features a hardened alloy steel cone with precise, flat bearing surfaces and steel jaws with wear plates that interact with the cone. A solid plate with slotted guides supports and directs the jaws, while a hydraulic cylinder provides the required clamping force. As the machine’s name suggests, the cone and jaws are designed to minimize gaps in the nominal position, ensuring a continuous surface during rotation.


Supporting the entire assembly is a frame that houses four forming rollers to create belt grooves and two curl rollers, all positioned by actuators. The part is first placed on a carriage by the operator, which then introduces it into the forming area. Here, the rotary expander clamps the part’s interior diameter while the adjacent tooling sharpens the profile, flanges or curls the end.


Similar to other Grotnes expanders, this machine’s HMI allows for the creation and storage of part programs. These programs, which dictate the start, slowdown and target positions, enable precise control over the machine’s forming functions. The operator-friendly HMI features multiple screens for monitoring and adjusting various machine functions, with the operator pendant conveniently located in the front.


The integrated part load/unload system is built into the main machine’s structure; it consists of a cradle or part rest that moves along a linear axis, placing the part over the rotating expander and then returning it to the operator/load position, helping to streamline the entire process.


How the Rotating Gapless Expander Works

Once the machine is set up with the correct tooling, the operator activates automatic mode and starts the process with the appropriate cycle-start button. The machine then autonomously grips and shapes the part, with rollers pressing the material against the expander dies to achieve final form. After the cycle, when the machine is idle at the start position, the operator removes the finished part. If the safety curtain is interrupted, the machine stops and will only resume once the obstruction is cleared and the operator manually restarts the cycle at the pendant.


Guided by Grotnes: Training and Troubleshooting

Prior to installation, Grotnes showcases expander capabilities through a functionality demo and two-hour dry run at our facility. This includes a one-time, 30-piece performance test on a single part size, using customer-provided or purchased tooling. On-site acceptance testing will replicate the initial factory acceptance test.


After ensuring pre-installation requirements are met by the customer, Grotnes will offer startup and operator training on-site. Training begins immediately after the final acceptance test or the following business day, covering machine operation, Grontes diagnostics, programming and routine maintenance.


For remote access and troubleshooting, machines are equipped with an eWON device; customers must provide internet connectivity for this feature. If alternative remote accesss methods are preferred, such as a dedicated VPN, customers can request a review from the Grotnes engineering team.


How Grotnes Can Help

Selecting the right equipment is essential in the manufacturing of washer and dryer drums. This is where Grotnes excels, not just in producing top-tier metal-forming technology, but also in guiding you to the appropriate machinery match for your production needs. Our expert team will walk you through the nuances of our offerings, ensuring you understand which machine aligns best with your specifications.


Grotnes is your partner in precision. Let us help you find the ideal solution to craft high-quality components that the appliance industry demands.

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