| 2 drying The veneered veneer contains a large amount of water and needs to be dried to a certain moisture content to be suitable for gluing or storage of the plywood. According to the needs of gluing, the moisture content of the veneer after drying should be 8%~12%, and the process conditions in the drying process of the dryer should be paid attention to, and the process operation should be properly adjusted to avoid the board falling due to the process, such as the edge of the board. Qu, cracks at the end of the board, uneven water content, etc. The dried veneer should be reasonably sheared according to certain specifications, and the shear deflection should not exceed 15 mm. However, during the sampling inspection, it was found that in order to grab the output, the artificial speed was accelerated and the moisture content of the veneer was high (sometimes reached 2). 0% to 40%). This not only reduces the quality of the semi-finished products, but also directly affects the quality of the plywood, because the moisture content of the veneers is too high, which leads to the opening and blowing of the plywood. The cutting is unreasonable, reducing the first and second grades, and even producing foreign goods and waste products. The veneer sorting process is a key process. The sorting should be carried out in strict accordance with national standards, and the use of superior materials and inferior materials should be guaranteed, so as to ensure that the economic benefits of the factory are maximized. However, in practice, some workers are working in a hurry and are not comprehensive in the national standard. Thus, a rating board that does not conform to the standard requirements appears. This not only causes material waste, but also affects the quality of the plywood, so the process standards must be strictly enforced. At the time of sorting, it was found that there were some problems with the board produced by the paperless seam-stitching machine, such as the defects of the end seam and the laxness, which still needs to be improved. Based on actual work experience, some improvement methods are proposed, as shown in Table 2. 3 Gluing, hot pressing The gluing of the plywood is to cure the veneer at a certain temperature under a certain pressure under a certain pressure, and firmly glue the veneers together. The main factors affecting the quality of the glue, in addition to the veneer quality of the veneer, the quality of the glue and the proper gluing process conditions are an important part. The factors that affect the quality of the glue before the glue is: (1) The moisture content of the veneer and the moisture content of the slab after the gluing directly affect the heat transfer speed of the slab, the penetration degree of the glue and the time required for the rubber pressure. Excessive moisture is not conducive to the improvement of the quality of the glue, prolonging the time required for hot pressing, and easily causing defects such as "bubbling" and "translucent". (2) When the usable time of the rubber exceeds the allowable range, the glue has deteriorated, which will reduce the quality of the glue. (3) The amount of glue applied is even and appropriate, and the aging time is affected by room temperature, and should be properly controlled in operation. In the rubberizing process, the conditions affecting the quality of the bonding are mainly temperature, pressure and rubberizing time. The press reaches a certain temperature to solidify the adhesive layer. The three-layer type II plywood produced by our factory generally has a hot pressing temperature of 110 to 120 °C and a certain pressure (10 to 18 kg/cm2). Under the appropriate time, the plywood can meet the process requirements. If the operator violates the process rules during operation, it will often cause many quality consequences. Such as large open glue and partial open glue, the bubbling and adhesive strength can not meet the prescribed standards, etc., in production must overcome the habit of random violation of operating procedures to ensure product quality. The defects of the plywood are classified into the following categories according to their properties and the influence on the quality of the product: defects in bonding strength, structural defects, appearance defects, and non-permanent defects. The following is a brief discussion of the defects and improvements in the gluing process, as shown in Table 3. In short, the factors affecting the quality of plywood are various, that is, there are management personnel, as well as the quality of employees, raw material quality and mechanical equipment status have a great impact on product quality. | |
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