Fig. 5 The development trend of band saw is that the common lever tensioning device is gradually developed into a steam hydraulic high tension mechanism to improve the accuracy and efficiency of material making; Single band saw develops to double band saw and four band saw to expand production capacity; The common single saw has developed into a chipper, which increases the chipping ability and is beneficial to the comprehensive utilization of wood. The circular saw machine developed from single-axis circular saw to double-axis circular saw, which increased the cutting diameter and reduced the sawing consumption. The new 8-rail mobile frame saw runs smoothly and improves the feeding speed. By changing the limiting device of the saw blade hydraulically, the plate thickness of the frame saw can be quickly changed, and the proportion of high-quality materials can be improved. The application of laser projector in band saw, circular saw and frame saw can improve the quality and output rate of wood. The application of microcomputer control device in various sawing machines further improves production efficiency and equipment performance.
The automatic throwing machine for log supply sorting has been applied to the chain log conveyor in the log yard of Wangqing Forestry Bureau, Jilin Province, China, realizing the mechanization of log sorting and throwing. Sawn timber selection and sorting equipment, in addition to manual sorting on the chain-type material selection platform, the Forest Products Industry Design Institute of the Ministry of Forestry also designed an automatic material selection and sorting device for frame bags, so that plates with different thicknesses can be automatically classified according to the thickness and fall into the designated frame bags, thus realizing the automatic sorting operation of sawn timber.
Before 1949, the mechanization of wood making in China was very low. After 1949, with the development of sawn timber industry, the degree of mechanization gradually improved. In 1950s, Northeast Timber Bureau established the first mechanized production line in Jiamusi. In the sixties and seventies, the mechanization of large band saw sports cars was realized. In the 1980s, chippers, laser projectors, computer-controlled rockers and computer-optimized saws began to be applied.
In northern Europe and North America, high tension band saws, double and multi-band band saws and wood chippers appeared in the late 1950s and 1960s. After the 1970s, computer-controlled wood manufacturing equipment was gradually developed, which improved the production technology of wood manufacturing.