The purpose of the technological process of sawing is to obtain from round timber (sawlog) sawn timber or to ready the sawlog for construction purposes.
Overall sawmill operations compose of many different operations including: the preparation of raw materials, the supply of logs to the sawmill, the feeding of the logs on the front-end carriages and the orientation of the log to the post, feeding into the sawmill frame and sawing on the frames of the first and second rows with the implementation of near-setting installation and transport operations, pruning un-edged sawn timber, sawing of sawn timber.
Outside the workshop, sawn timber is sorted by sections, the formation of drying bags, drying, quality control, final trimming and marking, sorting by grades and lengths, forming dense transport packages of sawn timber with subsequent shipment to clients.
Preparation of raw materials for sawing consists of sorting of sawlogs, debarking and removal of metal inclusions.
Before sawing, the sawlog is sorted by species and diameters.
Pre-sorting is performed in the stock of raw materials using longitudinal log transporters with beam spreaders.
The final sorting of logs is carried out in the pool before serving in the sawmill. The pool serves to wash the logs before sawing and sorting them, as well as for thawing in winter.
Debarking is an important part of the preparation of raw materials for sawing on a saw frame. As is known, the bark is the carrier of various kinds of pollution, including mineral (soil particles, sand, etc.). The transition to sawing raw material along with increasing the productivity of the sawmill stream allows to significantly reduce the wear and bluntness of the cutting tool, to improve the quality of the sawmill. At the same time, it becomes possible to process lump waste from sawmilling (slats, humpbacks) into a technological chips that meet the requirements of pulp and paper production, which strictly limit the admixture of the bark.
For debarking, our foresters use rotary-type machines with blunt co-extractors. Rotary debarkers have a frame on which the main machine components are installed - a stator, a rotor with a copulator, and mechanisms for feeding and receiving processed logs. The to be debarked log is conveyed to the feeding mechanisms by the conveyor, which pushes it through the hole into the rotor of the machine. When passing through the inner cavity of the rotating rotor, the log is processed (circumcised) along a circle (more precisely, spirally) mounted on the rotor by crescent-shaped crocheted forms.
With the help of rubber rings or springs, the crochet grippers are pressed against the surface forming the logs by working edges. When the blunted working edges interact with the log surface, thanks to the combination of the circular movement of the coroners and the forward movement of the log, debarking (removal of the bark strips) takes place along the helical line.
Before filing in the sawmill, sawlogs pass control for the presence in it of metal objects (staples, pins, nails, shell fragments, etc.). For this purpose, a special device is installed on the feeding mechanism - a metal detector, which is a ring detector with an electromagnetic device that reacts to the presence of metal in the wood. When the log passes through the metal ring of the finder with the metal, the device sends a signal and the log is removed from the stream. This prevents damage to the teeth or broken saws of the saw frame and the resulting losses in time and operational capability.
Continue reading at the drying process section.