Effective measures to improve the quality of 3mm plywood (1)

Abstract This paper points out that the thickness of the core plate is uneven, the core plate is rough (including burrs and groove marks), and the lamination and separation of the core sheets are the three main factors affecting the quality of the 3mm plywood as a thin veneer substrate. Three effective measures were taken to control the uneven thickness of the core plate, reduce the surface roughness of the core plate, and reduce the lamination and separation of the core plate. After the implementation of these measures, the quality of the product was significantly improved, and the core defect ratio was 59.0%. Reduced to 3 6. 3 %.

Due to the continuous improvement of people's requirements for living environment and working environment, the reserves of various natural precious tree species are decreasing day by day, and the demand for various high-grade thin wood veneers is increasing. The quality of the veneer is determined by the quality of the sliced ​​natural logs. The production process and management and the quality of the substrate are three factors. At present, 3mm glued sheets that can be used as veneer substrates on the market are in short supply, and the price is 2~3 yuan higher than that of ordinary plywood. Therefore, an effective way to increase economic efficiency for enterprises producing 3mm plywood is to improve 3mm plywood. The quality is such that it can be used as a substrate for thin wood veneers, and the quality is mainly determined by the effective control of the quality of the core during the production process.

1 Factors affecting the quality of 3mm plywood

The statistics and analysis of the 3mm plywood of a factory as a thin wood veneer substrate due to defects have been shown (as shown in Table 1): the influence of core defects on product quality is considerable, and the number of core defects 59.0% of the total output: the number of panels and other defects accounted for 10.1%: therefore the thickness of the core board is uneven, the core board is rough (including burrs and groove marks) and the core board is laminated and separated by 3 cores. Board defects are the three main factors affecting the quality of 3mm plywood as a veneer panel substrate.

2 Effective measures to improve the quality of 3mm plywood

The production process of 3mm plywood is shown in Figure 1. According to the above process flow, the quality of the core plate should be controlled from the steps of log cutting, core plate splicing, core plate repair and secondary repair.

2.1 Effective measures to control the uneven thickness of the core

2 .1 . 1 Control from the rotary cutting process. The thickness of the core plate should be theoretically uniform, but in reality due to the precision of the rotary cutting machine. The cutting conditions, the tree species to be cut, the growth stress inside the wood, etc., the thickness of the core plate has a certain deviation; as the core plate used as the secondary processing substrate, its thickness deviation of the rotary cutting should be controlled at ± Within 0mm to 0mm, the quality of the finished product can be guaranteed; therefore, in the rotary cutting process, we must: (1) Regularly check the wear of the rotary cutting machine, including the wear of the main slide, the looseness of the screw and nut of the cutter drive, If the pressure gauge and the tool holder are worn, repair or replace the parts if any abnormalities are found;

(2) Replace the rotary cutter and the timing re-grinding pressure gauge in time to ensure the quality of the rotary cutting. Control the appropriate crush rate;

(3) If there are many trees that are cut and cut, they should be classified according to the material properties, and the soft and hard materials should be separately cut and cut, and the veneers should be stacked and processed separately, so as not to be mixed together;

(4) During the rotary cutting, the single plate that is unscrewed when the rotary cutter is unscrewed and the rotary cutter exits the rotary cutting wood core is the most severe part of the thickness deviation. Therefore, the thinner and thicker portions should be cut off in time to avoid the inflow. The next process, resulting in the difficulty of production in the previous process. The initial thickness inspection and cutting of the spun wet plate was performed using a medium plate shearing machine, and the length of the medium plate cut length was adjusted to 1.3 m to minimize the number of core plate splices.

2 .1 . 2 The core plate due to the rotary cutting may have a large thickness deviation by the middle plate splicing machine, so it is necessary to use an automatic splicing machine for thickness detection. The commonly used jigsaw machine has a core plate thickness detecting mechanism, and as a core plate for the substrate, the negative deviation of the detecting mechanism is adjusted within 0.2-20.5 mm, (0.2 mm is the error range of the mechanism itself) The positive deviation is adjusted between 0.2 and 0.4 mm (to correct the positive deviation due to the warpage of the single board, the deviation can be slightly larger), and the amount of removal of the front and rear knives should be adjusted to ensure that the defect is completely removed. The chamfering knife should be removed from the re-grinding often. When installing the knife, adjust the gap between the upper and lower knives and control between 0. 0 3 and 0. 0 5mm to prevent the phenomenon of shearing.

2.2 Effective measures to reduce the surface roughness of the core plate The surface roughness of the core electrode refers to the processing marks left on the surface of the core plate obtained by the rotary cutting, that is, the microscopic uneven height. The reason for its occurrence is the influence of the process parameters of the rotary cutting, including the cutting angle of the rotary cutting, the angle of the loading knife, and the sharpness of the rotary cutter. On the other hand, different tree species and various defects of wood, distortion of texture, stress wood, thrift and so on. Therefore, in the rotary cutting, the cutting angle of the rotary knife, the direction of the wood cutting, the clamping position of the chuck, and the cooking of the wood should be adjusted according to the material properties of different tree species, so as to reduce the influence of adverse factors. When the material is soft, the cutting angle is between 19 ° and 20 °, and when the material is hard, the cutting angle should be adjusted to 2 1 ~ 2 2 °, to keep the sharpness of the knife, when the board has a burr groove Replace the new knife or pressure gauge in time when the marks or boards are raised. In the process of rotary cutting, a certain crushing rate is maintained. In addition, if the core plate with rough surface is found in the jigsaw process, it should be taken out in time and stacked separately. Ensure the quality of the 3mm core board used as the substrate.

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