Problems in the production process of laminated timber

2019-08-13 22:03:09
At present, the products produced by domestic integrated timber are mainly non-structural materials. The laminated timber is made of a short material that eliminates wood defects and is glued to the wood texture and joint position. Its products are beautiful in appearance and uniform in material, retaining the texture of natural wood, overcoming the shortcomings of easy deformation and cracking of wood. Using short materials, it can obtain the square board which can not be replaced by wood-based panels, which improves the use value of wood and is interior decoration. The ideal material for medium and high-end furniture.

Glulam is a popular new product in the international market. The main markets are Japan, Western Europe, the United States and other countries, of which Japan has the largest sales volume. In particular, the composite materials made of precious tree species such as ash, eucalyptus, etc., have excellent materials, beautiful appearance, are welcomed by foreign businessmen, and have a broad market in the world. The price of the laminated timber is very high. It sells about 50,000 to 150,000 yen for a door and frame parts in Japan. It is used to manufacture integrated boards for counters and desktops. The softwood is about 800,000 yen/m3, and the hardwood is 100. Yen/m3. Therefore, the active development of domestic integrated timber products can achieve high economic benefits.

This paper puts forward some opinions and suggestions on equipment introduction, production management, waste utilization and other issues, and provides reference for the production and future development and introduction of laminated materials.

Domestic integrated production status

Since 1998, China has invested in more than a dozen integrated timber factories (shops) in Heilongjiang, Liaoning, Jilin, Shanghai and other places, and some factories are under construction. In order to understand the production status of domestic laminated timber, we surveyed 8 integrated timber factories.

1.1 Process: material, one plate, one thickness, two sides, planing, one piece, one saw, one cut, one saw, one defect, one length, one finger, one four-sided planing, one plate, one glue, one set, one cold press, one sanding One-to-one product packaging and storage o1.2 Production equipment: The main equipment for the production of laminated timber is (excluding materials and drying equipment) two-sided planing, multi-blade circular sawing machine, cross-cut saw, finger jointing machine, four-sided planing , glue machine, group machine, wide belt sander, cutting machine. Glulam equipment is mainly imported from Japan, West Germany and Taiwan Province. It takes about 5 million yuan to introduce a production line equipment with a design capacity of 300h3/a.

1.3 Design ability: Investigate the design ability of the enterprise in 1 deletion. Printed 00m3/a, of which the design capacity of each production line is 1 deletion, 2500, 300h3/a, etc.

1.4 Tree species: mainly eucalyptus, ash and eucalyptus.

1.5 Adhesive: Finger joint and glue are evenly mixed with imported adhesive. Finger-joined polyvinyl acetate emulsion, the unit price of 270 yen from g; glue with polymer water-soluble isocyanate resin glue, the main agent 270 yen gl curing agent 1150 yen gl its ratio is 100: 15.

1.6 Tool: Generally use a piece of milling cutter with carbide, the tooth length is 10.12nuno

1.7 Product specifications: specific specifications and varieties, determined by both Chinese and foreign parties. The production of square materials is less, and the integrated materials are produced uniformly. Its specifications are thickness of 20.35, width 750. 120 () lI dish, length 1 赡 -50 () 0hRmo

1.8 Product use: All the laminated products are sold abroad, mainly used for manufacturing counters, writing desks, test benches and other furniture, as well as interior decoration materials such as stair side panels, treads, handrails, doors and siding.

1.9 Product quality requirements: Generally adopt the enterprise standard, which stipulates that the board surface (two sides) has no natural defects such as dead knot, live joint, decay, resin road and insect eye; the longitudinal finger joint has no gap; the sheet has no bending and warping deformation. The surface is free from damage, fuzz, sand marks and other defects that affect the appearance; the side faces are well processed. 1.10 Price: Depending on the site and product, it is generally 5 yuan - 5 yuan / m3.

1. U Mode of operation: Sino-foreign joint venture or compensation trade-oriented enterprises In order to accelerate the development of China's integrated timber industry and improve its economic benefits, in recent years China has introduced integrated production technology from abroad, which is undoubtedly correct, but there are many problems. Throughout the years of production and operation of integrated timber factories in various parts of the country, the current development is very uneven, only a few companies profit, most companies lose money; some can not be normal production, and some have not yet reached the design capacity and face the elimination Danger. This is the status quo of China's laminated timber production.

2 problems

2.1 The introduction of work experience The introduction of integrated production technology began in 1988. Due to insufficient introduction work experience or some unclear circumstances, many problems have been exposed.

2.1.1 The introduction work is biased towards the advanced nature of equipment and high-efficiency production lines, ignoring the current specific conditions and adaptability of production technology in China, which has led to the shortage of raw materials and waste disposal problems. Some equipments were found to be inapplicable after they were introduced, resulting in long-term idleness.

2.1.2 The introduction of work neglects the key issue of product quality standards, high product quality requirements, and low sales prices, resulting in a passive situation for the production of laminated materials.

2.2 Low yield According to the measurement, the production of 1m3 eucalyptus wood is 7-8m3 for logs and 2.3m3 for unqualified plates. The yield is 12%-15%. The main reasons for the low yield of laminated timber are:

a. Foreign companies conduct inspections according to enterprise standards, and product quality requirements are demanding. In the No. 601 standard of the Ministry of Agriculture and Forestry of Japan, the length of the section is 10Dxn or less, the dead length is not more than 2bnm, the long diameter of the insect eye is below 2Dxn, there is no decay, and there are no other wood defects such as discoloration and resin road. For specific regulations, only "very slight" is required; for the second-class material, the long diameter of the knot is 30Dxn or less, there is no dead knot, the crack long diameter is below 50Dxn, the long diameter of the insect eye is 10Dxn, and the decay requirement is "very slight", other wood defects “Slightly” is produced according to this standard, and Japanese companies produce products with a yield of 30%. 42%.

b. The precision of the material equipment is low, and the plate error is large. The thickness of the plate produced by the domestic material production equipment is 4Dm. If the thickness of the sheet is too large, the amount of shaving is large in the processing of the integrated materials; if the thickness of the sheet is too thin, it is treated as waste.

c. When the material is made, the width of the sheet is not determined according to the size of the laminated wood strip, which results in a large amount of high quality material being wasted.

d. The dry quality of the sheet is poor, resulting in an increase in dry deformation and cracking of the sheet, wherein the warping and cross-bending have a greater influence on the yield of the laminated material.

e. The processing margin of the laps is too large. The planing allowance for the width and thickness of the laminate (finger-joined wood strip) is 3.5M, and the sanding balance is 2.5M on both sides, so that the wood loss rate is 3% and 1%, respectively.

f. The removal of defects is a process in which the loss of wood is large. Due to the unskilled and unreliable operator, the quality materials are often removed without loss.

2.3 The scrap is not fully utilized. The yield of the laminated timber is 15%, and 85% of the scrap needs to be utilized. That is to say, the integrated material factory with an annual output of 300M needs 20,000 m3 of raw materials, and the waste amount is about 1.7 m3, including board skin, wood strip, short material and sawdust, shavings and wood powder. At present, companies are trying to use these wastes in various ways and get initial results. However, due to limited conditions, these wastes have not been fully utilized, especially the amount of sawdust and shavings. Difficulties in use are yet to be further explored and studied in the future.

2.4 Adhesives and tools depend on imports At present, the adhesives and tools used in production plants are all dependent on imports. Due to the high price, the cost of the product is increased. In particular, the storage period of the adhesive is only 3 months. It is generally shipped by ship and has a long transportation time. Due to the lack of detection means in production, the quality of the product is unqualified due to the use of expired adhesive. Individual companies have found returns for this reason.

2.5 Insufficient raw materials The eucalyptus and ash are precious species, and the domestic resources are sharply reduced. Together with the export of logs, the raw materials of the integrated timber factory are insufficient. In order to prevent dry deformation, it is generally natural to dry for a period of time, which not only requires an increase in the plant area, but also requires large liquidity, and individual enterprises cannot produce normally due to insufficient liquidity. In general, the laminated timber should use small materials and low-quality wood as the raw materials, and in the feasibility study report of the plant, the economic benefits are calculated by using small-diameter wood as raw material. However, in order to increase the yield, some companies use high-quality logs of large diameter, so the price of raw materials is high, which increases the cost of the products.

2.6 Management problems of enterprises In addition to individual enterprises, most of the integrated material factories have weak technical strength, equipment maintenance and quality management, and insufficient production experience, resulting in low product qualification rate. Due to the high price, the unqualified products have no market in the country and have to be stacked and stored, which undoubtedly increases the cost of the products.

3 suggestions

3.1 It is recommended to stop using the imported equipment to build a factory. If it is necessary to introduce equipment to build a factory, we should consider the characteristics of China's national conditions and reduce the blindness of the introduction work; the design capability should be small and not large, choose equipment with low applicable price, and try to adopt The method of matching foreign special equipment with domestic general equipment; the production of integrated timber can be used as a workshop of integrated processing plant, so as to achieve comprehensive utilization of wood without adding equipment.

3.2 The factory will unite and concentrate on the technical strength to manage the existing integrated material factory to maximize its ability to completely reverse the current passive situation, improve product quality and utilization of wood, and increase economic benefits.

3.3 In the production of laminated timber, comprehensive utilization of multi-level and multi-species is carried out to make full use of the surplus of the laminated timber. There are many ways to use waste, and there are roughly:

a. The board is left deep-processed, or the board is used as a raw material for wood-based panels.

b. Reduce the standard for the removal of defects in the slab, and use the remaining short material to process the slab as a raw material for furniture.

c. The core board of the blockboard is manufactured, and the blockboard can be manufactured if the veneer material and equipment are used. d. Use short materials to process floors or make wooden toys. Tests have shown that using the remaining short material to process the blockboard core material can increase the yield, 14.8% of eucalyptus and 15.5% of ash.

3.4 Realize the localization of adhesives and tools as soon as possible, and introduce technology into digestion and absorption, and combine innovative work to develop special equipment for integrated materials suitable for China.

3.5 Develop national standards as soon as possible so as to adapt to the needs of domestic production development, facilitate enterprises to organize production, conduct quality supervision and management, and thus promote the improvement of product quality.

3.6 Try to use low-quality wood and small-diameter wood to produce laminated timber, and limit the export of precious logs of eucalyptus and ash.

3.7 Increase the range of tree species of integrated materials and expand product specifications and types. While developing the processing of integrated materials, it is necessary to simultaneously develop research on the application technology of integrated materials and open up the domestic market.

3.8 Strengthen quality management, strictly control each process, organize production according to quality standards, improve product quality and first pass rate.

3.9 Minimize the processing allowance of the laminated timber. According to the data, the Japanese company's sheet thickness deviation is 11nM, the thickness is 1nM in the shrinkage, the sheeting allowance is 1-2DM, and the sheet width and thickness planing margin is 1 .5 delete, the amount of sanding on both sides is 1.5

3.10 The material should be determined according to the size of the laminated timber strip to increase the yield. The sheet material produced by this method can increase the yield by 6%.

For the problems existing in the current domestic integrated timber production, the above suggestions we have made can benefit the introduction and production of the integrated materials technology, which achieves the purpose of this paper. In short, although there are many problems in the production of laminated timber, the production process of the product is simple, the equipment investment is small, and the small material can be turned into a large material, and the policy of “inferior materials and economical use” can be realized to make up for the shortage of high-quality materials. Meet the needs of society. If multi-level and multi-variety comprehensive utilization is carried out in the production of laminated timber, the cost of the product will be greatly reduced, which can make up for the low yield of the product and the high cost. Taking these factors into consideration comprehensively, the development of the integrated timber industry has its practical significance and economic value in the context of the shortage of domestic timber resources and the reduction of high-quality materials.

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