ERHART HOLZ, AUSTRIA: Hole Rotor Debarking Machine ZE 1105
Perfect debarking: Pressure adjustment even while the machine is running
Erhart Holz, a company based in the Great Walser Valley, Austria, specialises in cutting heavy timber. To optimally process this high-quality material, a robust debarking system is essential.
In 2014, their new log yard went into operation at Erhart Holz in Sonntag. The new construction was needed due to the huge amount of effort that had been previously required to process round timber. Since November 2014, a modern system has been in operation – to the satisfaction of managing directors Ignaz and Joachim Erhart. For the debarking process, they had opted for a hole rotor debarking machine from Baljer & Zembrod: the ZE 1105 with Variopress adjustment system.
The machine, which weighs around 13 tonnes, can handle conveying speeds of up to 32 m/min. The rotor can be opened from 12 to 110 cm – a large aperture necessary due to Erhart Holz’s specialisation in cutting hardwood from both the local region and Switzerland. The average annual diameter is 50 cm, which the entire system must be able to handle.
‘In terms of the maximum possible diameter, the ZE 1105 is the largest system we offer for rotor debarking. The entire rotor can be raised and lowered,’ explains Baljer & Zembrod's Managing Director, Peter Schaeidt. In addition, the ZE 1105 includes a self-centring device. The rotor thus positions itself based on the diameter of the trunk. Five debarking arms are flange-mounted on the body. These have a curved shape and are equipped with blades with a soldered cutting edge. The feed unit consists of a sturdy in-feed chain bed on the intake and exit sides with two conveyor chains and welded-on carriers. The hold-down devices include a pair of tapered rollers mounted on bearings on the intake and exit sides. The hydraulic unit is equipped with oil heating and cooling.
Advantages that speak for themselves
Erhart also chose the optional Variopress adjustment system. Depending on the condition of the bark or trunk, the blade pressure can be adjusted – even when the rotor is running – via its own hydraulic power unit with integrated pressure relief valve and pressure gauge. ‘I didn't want to forego this extra convenience,’ explains Erhart. ‘Especially with the silver fir, which is very difficult to debark, we get great results.’ With Variopress, logs that have already been debarked can also be conveyed through the ZE 1105. In this case, the blades are opened. If malfunctions occur in the system, the blades open automatically.
Another advantage is the time savings, since the pressure adjustment makes system shutdowns unnecessary. In the patented Variopress system, a closed hydraulic system is integrated into the rotor. The power feed and signal exchange take place via copper slip rings with swivelling current collectors. ‘We achieve almost lossless signal transmission because the current collectors are only swung in when needed,’ explains Schaeidt. Erhart is also pleased about the low operating costs of the debarking system, as the ZE 1105 does not require expensive compressed air.
About the company Erhart Holz:
Managing Directors: Ignaz & Joachim Erhart
Cutting capacity: Up to 60,000 m³/year
Products: Dimension lumber, rift/semi-rift wares, carpentry goods, finger-jointed wares, packaging
Sales markets: 30% regional, 10% rest of Austria, 60% export