There are various types of material selection devices. According to the degree of mechanization, it can be divided into manual sorting device and mechanical sorting device; according to the configuration of the material selection line and the workshop, the material selection device is divided into longitudinal movement, lateral movement and circumferential movement of the sawn timber; The sorting and automatic fall sorting devices are divided into single layer and multi-layer distinguishing devices according to the number of layers of the divided materials.

(1) Manual sorting device.

In domestic production of wood, most of the materials are manually sorted. Most of them use vertical and horizontal movement of sawing materials, and circular sorting devices are used abroad. Wood shredder 1 Longitudinal material selection device: It is the simplest one in the material selection device. This material selection device is a material selection shed in the workshop outside the production line. The sawn timber is transported out of the workshop by a longitudinal belt conveyor. Firstly, the material selection and inspection workers on both sides of the transportation line are piled up according to the material type, specification and material length of the sawn timber, and then they are inspected and evaluated, and then piled into concrete, which is transported by the flatbed truck or forklift to the yard stacking.

The longitudinal material selection device can stack and stack the plates on both sides of the transportation line. The arrangement of the plate piles is usually parallel to the longitudinal direction of the transportation line. Therefore, the finer the sawing material is divided, the more piles are piled up, and the longer the ground, the longer the material selection field is. . In order to facilitate the drawing of sawn timber, the pumping section is made of roller conveyor, and the speed of the material should not be too fast, generally 15-20m/nun, so the productivity is low. This kind of material selection device is only suitable for the variety of sawn timber, the site allows Adopted under the conditions.

2 Horizontal material selection device: It is often used in large and medium-sized timber enterprises. This device is mostly chain transport, and the running direction of the sawn timber is perpendicular to the longitudinal direction of the transport line, that is, in the direction of the pumping. After the sawn timber is transported out of the workshop and replaced by lateral movement, its running speed can be reduced to 1%10-1/15 of longitudinal transportation.

Therefore, this device can meet the high productivity requirements of the workshop, and can be used to evaluate and distinguish the sawn timber. Four to five transport chains with different pitches and parallel to each other are installed on the material selection table. The width of the material selection table is less than 1 to 1.5 m of the longest sawn timber, so that the material selection is easy. On both sides of the material selection table, there are corridors with a height lower than 0.75-0. 8 m. There are movable rollers on both sides of the corridor to facilitate the extraction of sawn timber and reduce labor intensity.

The transverse chain material selection device consists of three parts, namely the sawn timber receiving part, the inspection evaluation part and the sawn timber drawing part. The sawn timber receiving portion carries the sawn timber sent from the workshop by the belt conveyor, where it is turned from the longitudinal direction to the lateral direction, and the belt conveyor and the lateral transport chain are connected by the sliding device. The inspection and evaluation part completes the inspection and evaluation of the sawn timber and the marking or stamping work, and then transmits it to the sawing material sampling section, and the sawn timber is still slowly advancing in this section. The sawn timber drawing part is the sawn timber that will be evaluated, and is sorted according to the material type, specification and grade, and placed on the corresponding pile. The order of the plate is to first draw the plate material with a larger specification, and then to extract the medium and thin plates with small specifications.

For large-scale woodworks with large material production and high productivity, two-layer material selection site can be built. The length of the selection field can be shortened, but the height of the building increases. The characteristics of the horizontal chain material selection device: continuous material selection and pumping, which occupies the ground side, and the labor intensity of the workers is small, which can reduce the selection and extraction of personnel. But sometimes it is easy to choose because it is not clear.

3 circular sorting device: the whole material selection field is designed into a disc shape, after the plate shipped from the material workshop is sent to the disc, the saw material is moved in a circular motion, and the material inspection worker evaluates the score outside the circle. . Its characteristics are suitable for the case of many varieties and few blocks. The sawn timber should be placed circumferentially at the beginning, otherwise it will affect the production efficiency.

(2) Mechanical automatic sorting device.

The mechanical automatic sorting device has various falling sorting devices and multi-layer chain sorting devices. After completing the inspection and evaluation of the sawn timber, the corresponding silo is delivered according to its specifications, and the combined with the microcomputer control has a good effect.

1 Falling sorting device: Generally, the sawing timber is transported to the silo by the "L" or "J" shaped hook. The sawn timber falls from a height to a silo. In order to avoid the damage and transfer of the sawn timber, the silo is designed in various forms, such as a tilting silo, a sling silo and a self-propelled trolley.

The process of mechanical automatic material selection is: after the sawn timber is shipped out of the workshop, it is firstly subjected to manual evaluation and specification testing, and the corresponding silo is controlled by a computer storage memory device. The sawn timber is mechanically arranged, divided into individual pieces, and arranged neatly into a single layer so that the sorting machine feeds in an orderly manner. After the sorting conveyor receives the finished sawn timber, it runs along the line above the receiving port of the silo. When the sawn timber reaches the corresponding silo opening, the microcomputer issues a command, which is raised by the retaining block to make the sawing material fall. Man silo. When a certain amount is accumulated in the silo, the unloading is sent to the transport equipment for stacking, storage or drying.

2 Sawn timber multi-layer sorting device: It is mostly used in sawn timber planing workshop. It has some significant advantages. It does not hurt the surface of sawn timber, has fewer failures, high speed, stable operation, and continuous control of sawn timber in and out. It is possible to accurately calculate the number of blocks for plates of different sizes, so that the front and rear sawn timbers can be separated from each other.

Modern chain multi-layer sorting devices and their feeding and discharging equipment are somewhat different due to different mills. However, they are generally composed of five main components: a feeder (generally inclined), a roller conveyor, an accumulation section, a storage section, a discharge machine or a movable unloading device. The sorting process is such that the sawn timber is fed into a designated layer through a tilted feeder and then slid along the roller conveyor to the accumulation section. They are counted during the accumulation of sawn timber. When accumulating a sufficient number of blocks, the sawn timber separates from the sawn timber behind it and enters the storage section. The material handler can use the movable unloader to unload the sawn timber from the storage section onto the stacker.

(3) Stress grading devices.

Most of the above-mentioned devices are manually inspected and evaluated, and the appearance defects, processing geometry, and dimensional deviation of the sawn timber are visually evaluated by the naked eye, and thus there are many disadvantages. If the mechanical properties of the sawn timber cannot be reflected, the relevant parameters cannot be provided for the engineering design, resulting in waste of wood use; due to observation errors, the classification is inaccurate; the sorting efficiency is low and the labor intensity is large.

The sawn timber stress grading device is graded according to the strength and stiffness of the wood, that is, the sawn timber grade is determined according to the correlation between the elastic modulus of the wood and the flexural strength. After non-destructive testing, the strength of sawn timber can be predicted, which provides a theoretical basis for the rational use of sawn timber, and is especially suitable for building structural materials.

As shown in Fig. 3-1, the sawn timber is fed by two pairs of rollers, and is supported by two smooth surfaces to support the rollers. The pressure roller 9 protrudes upward to make the saw material reach a constant deflection, and the bending force is converted by magnetic elastic force. (sensor) measurement. As long as the bending force is measured, the strength of the sawn timber can be calculated by the formula.

The deflection of such a device is preset, which simplifies the loading mechanism. However, some stress grading devices adopt a method in which the bending force is constant and the deflection is changed, and there are two points of load, so that the structure is relatively complicated. The stress classification of sawn timber is still in the research stage in the country. It is necessary to formulate corresponding national standards and gradually promote the implementation, which has broad prospects.
 

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Stop Valves are closed by screwing a rubber gasket down onto a seat in the middle of the valve. Pros only use small versions that act as shutoff valves for fixtures such as sinks and toilets and outdoor sillcocks. Flow is inefficient because of the circuitous route the fluid (water, in most cases) has to follow. It's important to orient the valve in the right direction with the arrow (cast into the side of the valve) aligned with flow direction. That way, water flows against the bottom of the rubber gasket. If the valve is put in backward, the flow will force the gasket away from the top of the valve.

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