cut down on
The operation of cutting down upright trees. When logging, use cutting tools to cut off and lodging at the root of the stumps. According to the tools and equipment used, it can be divided into manual logging, portable mechanical logging and self-propelled mechanical logging.
Cutting will not only affect the follow-up process, but also affect the utilization and renewal of forest resources. Logging operation should meet the following requirements: ① Control the direction of falling trees. Don't overlap with fallen trees, create favorable conditions for pruning and skidding, and be careful not to damage the mother trees and young trees needed for renewal. ② Reduce root cutting. The maximum height shall not exceed 10 cm to make full use of wood. (3) When logging, stumps such as falling wood should be reduced to avoid splitting and core pulling. (4) the whole cutting, all left.
Logging technology
When logging with hand tools and hand tools, the following logging techniques should be adopted: ① Judging the falling direction of trees. According to the inclination of the trunk and the position of the center of gravity of the crown, we can judge the natural trend of trees and determine the direction of logging. When the diameter of the tree is large, it is naturally inclined or the eccentricity of the crown is large, it is difficult to control the falling of the tree by general methods, and it can only be naturally inclined. (2) Saw (cut) hawthorn. Saw (cut) the hawthorn mouth at the root and logging side (Figure 1). The opening of the lower hawthorn mouth is 30 ~ 45 half-moon (the opening is parallel), and then the sawdust in the opening is taken out. Its depth should be 1/4 of the trunk diameter, and the depth of hawthorn under oblique trees and broad-leaved trees should be increased to 1/3 of the diameter. ③ I saw the hawthorn. Saw the upper hawthorn mouth on the opposite side of the lower hawthorn mouth, and its height is about110 of the root cutting diameter from the bottom of the lower hawthorn mouth. 4 "Leave strings". There is a "string" between the upper and lower hawthorn, the diameter of which is about110. When the trunk falls, the "string" will break slowly. "Chord" is a very important axis to control the falling direction of trees, slow down the falling speed of trees and ensure safe logging, so it must be preserved as needed. ⑤ Wedge. Finally, the wedge is driven from the upper hawthorn mouth, and the upper hawthorn mouth is lifted, so that the standing tree falls in the predetermined direction accurately. In addition, in order to prevent the occurrence of "core pulling phenomenon" and the loss of the core of the root joint material, when sawing hawthorn, the tip of the chainsaw can be inserted into the heartwood for horizontal sawing (Figure 2a). When the predetermined cutting direction is inconsistent with the natural tendency of trees (borrowing trees), the side should be tilted to increase the width of the "chord" (Figure 2b) to ensure that the trees turn backwards, which is conducive to safe operation. When the inclination of the standing tree is large, its turning direction should not exceed 10. In order to prevent the steep trees from splitting when cutting, you can saw "triangle strings" on both sides of the upper hawthorn, and then slowly saw the hawthorn mouth from the top of the triangle until the tree fell down to prevent the wood from splitting. The sawing sequence is 1, 2 and 3 (Figure 2c). ⑥ Pay attention to safety. Before logging, vines, shrubs and fallen trees around the trees should be removed, and a 2-4-meter-long safe road should be made behind the fallen trees for workers to avoid when the trees fall. Loggers should wear hard hats, tight-sleeved clothes and non-slip shoes when working. Logging is prohibited in strong wind, heavy rain, heavy snow, fog and dusk. A safe distance of more than 70 meters should be kept between loggers and pruning, skidding and lumber making workers. In logging operations, a warning should be given before the trees begin to fall, so that people nearby can quickly avoid them.
Figure 1
Fig. 2 Logging tools and equipment
Tools used in manual logging include curved handle saw, pot-bellied saw (double saw) and axe. The handheld machine is a gasoline-powered chain saw. The saw chain is cut by power, but people need to hold the saw to move it. This is the most widely used logging machine in the world at present. Since 1970s, self-propelled mechanical logging has been applied in developed forestry countries. This machine is operated by workers in the driver's cab and uses hydraulic chain saws or knives to cut wood. Most of them have grab arms to control the opposite direction. Safe operation and high efficiency. This kind of machinery has a single process of logging machine, but also a combination machine combined with other processes, such as logging stacker, logging pruning machine, logging skidder and so on. (See Cutting Area Operating Mechanical System). Most of these self-propelled loggers can only work in places where the slope is not too steep.