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Servo motor and drive technology cuts timber production time

Based in Kendall on New South Wales’ mid-north coast, AE Gibson & Sons manufac tures sawmilling equipment, log carriages, resaws, multisaws and board-edgers, as well as automatic sorters and stackers, transfers and conveyors. All of AE Gibson & Sons’ designs are engi neered to maximise product quality and production throughput. This is particu larly so with one of the company’s most recent developments — an electric motor- driven automated end-matcher machine.

The first-phase evolution of AE Gibson &Sons’ automated end-matcher introduced standard motor and drive technology, in place of a traditional pneumatic system. However, recently the company developed this technology further, teaming up with SEW- Eurodrive, to design a servo motor- based end-matcher for timber product manufacturer, Coffs Harbour Hardwoods (CHH).

End-matching is a floorboard production step, which involves cutting a tongue or groove joint at either end of the board respectively. End-matched floorboards permit floorboard joins to be placed between the floor joist or battens, resulting in less wastage than plain-end flooring, which must have its ends fixed over a joist or batten. As part of a progressive plant upgrade, CHH recently replaced its legacy pneumatic end-matching machines with two servo motor-driven end-matchers from AE Gibson & Sons.

In operation, boards of varying length are introduced to the end- matching area via a large chain-conveyor table. One-by-one, boards are raised off the conveyor and held in position using two rail-mounted L-clamps — one top mounted and the other bottom- mounted. The closed L-clamps drive the board through a stationary profile cutter, forming a tongue or groove at the board’s end. The board is then lowered back on to the conveyor, transferred to the other side of the chain-conveyor table via sets of lateral rollers, where the profile cutting process is repeated.

Each end-matcher incorporates a pneumatic system, which provides the up/down movement of the lower L- clamp, while SEW servo motors provide left/right movement of both clamps. Here, the bottom clamp drives the board forward through the profile cutter, while the top clamp applies pressure in the opposite direction to hold the board in place. Once cut, the clamps return to the start position, ready to accept the next board.

“The latest evolution of our motor- driven end-matcher required more sophisticated drive technology than the previous version, so we got SEW involved,” says Christian Gibson, AE Gibson & Sons Manager – Electrical Control. “Together, we were able to make some significant improvements on the original design, resulting in an extremely fast and accurate end-matcher.”

Both end-matchers are equipped with two SEW-Eurodrive geared servo motors. Each servo motor is paired with the company’s MoviDrive ‘B’ application inverter, while the MoviTrac standard inverter is used to drive the site’s two profile cutters. All electronic drives are linked to a programmable logic controller (PLC) via a DeviceNet communications network, and can be configured via a user-control panel.

According to Martin Broglia, SEW- Eurodrive NSW Sales Manager, the MoviDrive ‘B’’s integrated IPOS posi tioning and sequence control is vital to the accurate operation of the end- matcher. “The IPOS control with encoder feedback is ideal for accurately positioning the L-clamps and ensures a straight profile cut every time,” he says. “It meant that AE Gibson & Sons and CHH could avoid the use of proximity switch-based positioning systems, which must be continually maintained and manually adjusted.”

“The new end-matcher machines produce an improved finish on the profile cut compared to our legacy pneu matic system,” says Garry McCarthy, CHH General Manager. “The end- matcher’s precision positioning combined with its strong clamping means we are able to achieve consistently square cuts.”

Further flexibility is achieved via the control network architecture in place at CHH. “Parameters for all of the MoviDrive ‘B’s can set and adjusted via the on-site PLC,” says Broglia. “This is a real time-saver, as it means program ming, system maintenance and trou bleshooting can be performed across the DeviceNet network.”

With a design throughput rate of 25 boards per minute, the new end-matcher has been developed with speed in mind. More than doubling the typical throughput rate of pneumatic end- matchers (12 boards per minute), the servo motor-based end-matcher incorpo rates some clever system design and drive programming.

Importantly, each of the end- matcher’s servo/ MoviDrive ‘B’ combi nations has the ability to switch operating modes.

“When the board is being driven through the profile cutter, the top L- clamp servo motor is operating in torque control mode, applying force against the lower L-clamp, while the bottom L- clamp servo motor is operating in posi tion control mode,” explains Broglia. “Once the profile cut has been made, the top servo changes its operating mode from torque to positioning, to allow an accurate return to its starting point. It’s this kind of flexible operation that permits such a fast processing rate.”

This sentiment is shared by Gibson. “The MoviDrive ‘B’’s multi-mode controller card provides high levels of flexibility,” he says. “It permits the unit to support a broad range of applications, from the very basic control of an asyn chronous motor in V/F operating mode, through to precision dynamic control of servo motors.”

“The new end-matchers produce finished boards faster than we can pack them,” says McCarthy. “However, we are able to configure the units to deliver finished boards at a rate matched to our current packing capabilities, or ramp it up to meet production demands. It provides real operational flexibility.”

The new end-matchers were incorpo rated into CHH’s existing timber production facility. Here, it was impor tant that they integrate seamlessly with the site’s other equipment, such as its profile cutters and chain-conveyor tables.

“Given that this was the second evolution of the end-matcher, much of the base programming was similar to the original. However, SEW worked with us and CHH to develop the code inside the drives for the processes unique to the servo motor applications,” he says.

“Furthermore, as the SEW servo motors are extremely compact, installa tion in the space-limited end-matcher was simplified.”

In addition to an increased throughput capability, the latest evolu tion of AE Gibson & Sons’ end-matcher boasts additional features. “The servo motors are totally enclosed and rated to IP65,” says Broglia.

“They are also fanless which means they are not susceptible to the large amounts of sawdust on the production floor.”

With the end-matchers online, CHH is looking to the future. “The new end- matchers are performing well and providing us with high levels of opera tional flexibility,” says McCarthy.

[Ben Lazzaro is senior technology writer, Relate Technical Communications.]

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