Professional training would be good for most of the Plywood QC/QA Parts 72: Quality problems and solving methods in the production of plywood

Quality problems and solving methods in the production of plywood  胶合板生产过程的质量问题与解决方法

在生产过程中,以上原因所造成的产品质量波动需要通过分析才能找出,这样才能及时解决以稳定产品质量。
In the process of production, the product quality fluctuation caused by the above reasons can be found through the analysis, so as to solve the product quality in order to stabilize the product quality.
一、单板拼缝的质量问题
The quality problem of the veneer joints such as gaps and overlaps , or joint seam
由于适宜做表板的优质原木日益减少,绝大部分胶合板生产厂对表板都采用胶拼工艺,以提高表板出材率。表板的胶拼质量关系到以后的组坯操作和合板质量,在胶拼中可能遇到的质量问题、产生原因、及解决方法如下:
The good quality logs are suitable  for using to peel to  the top/bottom surface core veneer are decreasing, most plywood production manufacturers have been trying to use diffierent kinds of veneer joint skills to improve or upgrade the veneer quality and grades ,such as scarf joint ,butt joint ,finger joint and stitched joint    in order to improve the surface veneer quality levels rate. The quality of the core veneer  is related to the quality of the veneer core lay-up ,the quality of the plywood. From the veneer joint methods and process ,we can find The quality problems, causes and solutions are as follows:
质量问题:1、拼出的单板端头不齐
Quality problems: 1, Core Veneer edges are not in alignment and neat and straight ,the core veneer are not lined up .
产生原因:拼缝操作不当所致,在纵向有带胶拼机上进料时两边单板端头未对齐;或者是单板齐边时不成矩形所致。
Cause: the joint gaps/Overlaps were  caused by improper operation,When feeding the veneer into the veneer joint machine , ,some of the veneer are not aligned on both sides ; or veneer edge is not  rectangular and not neat before match them .
解决方法:加强操作人员的责任心和提高操作技术水平;单板齐边时应有一个基准,不可将单板剪成平行四边形。
Solution: to strengthen the operator’s responsibility and improve the level of operation of the technical level; Veneer edges Alignment/Straight and Neat should have a benchmark, Can not accept to  cut the core veneer into a parallel quadrilateral or other shapes .
质量问题:2、拼缝过紧或过松
Quality problems: 2, the joint seam is too tight or loose
产生原因:拼缝机的进料挤紧辊调整不适当造成的。
Cause: Caused by the not good adjustment of The squeezing roller  of the veneer joint feed sewing machine adjustment  .
解决方法:调整拼缝机工作台面下的一对锥形挤紧辊,使之合适。
Solution: adjust the squeeze roller of the  sewing machine  to meet the requirements of the feeding .
质量问题:3、胶带粘贴不牢
Quality issues: 3, adhesive tape’Bonding strength  is not good .
产生原因:胶纸带未充分湿润,拼缝机加热辊的温度过高或过低;上轧棍压力不够。
Cause: the tape is not fully wet, sewing machine heating roller temperature is too high or too low, the roll pressure is not enough.
解决方法:将胶纸带用水充分湿润;检查加热辊;增加上轧棍压紧力。
Solution:Make sure the glue tape fully wet; check the heating roller; increasing roll pressing force.
质量问题: 4、拼出的木质面皮单板色泽或光洁度不一致。
Quality problems: 4, the face veneer color or finish is not consistent.
产生原因:配板工在配板时选料不当,未做到“原棵搭配”;拼板操作时两片单板正、背面不一致,松面、紧面搞反了。
Reason: 
解决方法:提高操作工的技术水平,多进行技术培训,和加强操作工的工作责任心。
Solution: to improve the technical level of operators, more technical training, and strengthen the operator’s sense of responsibility.
二、组坯的质量问题组坯易产生的缺陷、原因和解决办法
Two, the quality of the veneer core lay-up prodcess,manufacturing defects and reasons and solutions .
缺陷1:叠芯离缝
Defect 1: core gaps
原因:组坯时零片单板间的位置放置不当;板坯搬动时受碰撞造成芯板错位。
The reason: when making the core veneer lay-up if put the core veneer to  incorrect place; Or when moving the veneer core platform( before hot pressing and cold pressing process )will cause dislocation of the core veneer  .
解决方法:涂完胶的芯板要经陈放一会再组坯;组坯后要预压,使板坯初步粘结在一起,不易移位;提高组坯工的组坯技术水平。
Solution: After the dry veneer glued with glue ,can condition the core veneer for suitable the lay-up  and then make the lay-up .After lay-up ,need to do the cold pressing process ASAP and make sure every layer of the core veneer glued together and can not accept the core veneer move or shift. Improve the technology and skill of the veneer core lay-up workers.
缺陷2:缺边、板坯边缘不齐
Defect 2: edge shortage defects, edges are not neat and aligned and lined up.
原因:芯板长度不足,组坯操作时未按照“一边一头齐”的原则做;表板边缘缺损。
Reason: the core veneer  length is insufficient, when doing the VC Lay-up operation are not in accordance with the “One side/edge must be lined up and aligned and neat ” principle to do; The top and bottom surface core veneer have edge defects.
解决方法:进货时严格控制好芯板长度和表板幅面尺寸;组坯时应有一个直角基准边;加强生产管理,提高操作工技能和责任心。尽量用熟练工。
Solution: strict to control the core veneer length and  sizes, When doing the Veneer Core lay-up ,should have one benchmark that  one right angle core veneer as the reference edge; strengthening production management, improve operation skills and sense of responsibility. Try to use skilled labor.

三、预压的质量问题及解决方法
Three, the quality of  Cold pre-pressing problems and Solutions
在胶合板生产过程中,预压工序的质量问题主要反映在预压效果不理想,预压后的板坯不能成型,达不到预粘合的效果,或者预压后出现叠离芯现象等。有关这方面的缺陷、产生原因、及解决方法如下:
In the plywood production process, the Main quality problems of cold pressing process is the cold pressing effect is not ideal, the veneer core platform cannot be formed after cold pressing, can not up to the  bonding effect, or have so much core  voids and overlaps after cold pressing . The defects, causes and solutions of this area are as follows:
缺陷1、预压效果不理想,每层单板间未很好粘合。
Defect 1, pre-pressing effect is not ideal, each layer of the core veneer is not very good adhesion.
原因:预压胶的粘度不够;预压时间掌握不当;一次预压的板跺厚度太大。
The reason: the glue viscosity of prepressing  is not enough; prepressing time is out of control, The quantity piece of the platform are overload and height is too high  .
解决方法:制胶时控制好胶的粘度,脲醛胶应为800-1400cp,酚醛胶为1000-1800cp;调胶时可适量加入面粉或聚乙烯醇来增加胶的粘度,并 掌握好不同气候条件下调制胶液的活性期,使预压处在树脂由A阶段向B阶段转化的时期,预压胶的活性期控制在2h左右为宜,通俗说法为,预压好的板坯当揭起 单板时胶应略有“拔丝”现象。
Solution: control the glue adhesive viscosity  when making the glue, urea-formaldehyde glue should 800-1400cp, phenolic glue is 1000-1800cp; when mixing the glue may  add some wheat flour or polyvinyl alcohol to increase the viscosity of the adhesive, and master the modulating the activity of the glue with  the different climatic conditions  ,as the popular saying, when tear the presseed glued veneer core should be a slight “candied /drawing ” phenomenon  ( When tear the glued veneer  will have glue thread / spin filaments    linked the adjacent glued veneer ) .
为了使预压压力均匀地传递到每一张板坯的幅面上,因此,一次预压的板跺高度不宜超过60厘米为好。
In order to make the pre-pressure evenly delivered to each veneer on the surface, therefore, the maximum height of the hot presing plates open size should not exceed 60 cm as well.For example ,no more than 30 pieces of 1220x2440x18mm plywood every time for cold pressing.
缺陷2:预压后出现叠离芯现象
Defect 2: after the pre-pressing have the quality problems of  overlapping core and core voids .
原因:搬动板坯进入预压机时芯板发生错动;组坯用的芯板严重翘曲变形,边缘没有剪直,铺板的时候没有铺到位或者严重影响了铺板质量。
Reason: When move the core veneer platform  into the pre-pressing machine, the core veneer are slip and shifted ; core veneer  with serious warpage, did not cut straight edge and cause shear dislocation ,or did not make a good veneer core layup and downgraded the quality.
解决方法:在生产过程中要文明生产操作,不可蛮干;同时注意对意杨等速生材树种的芯板在使用前应进行整平处理(柔化),并进行二次齐边,使之表面平整,边部成直线。
Solution:Train all the workers must be civilized production operation in the production process, can not act recklessly; pay attention to the fast growing wood poplar core veneer before use  them ,make sure the core veneer flat and softening, leveling and two times edge trimming,To make the smooth surface, The edge are  lined up and straight .
四、胶合板热压质量问题、产生原因及解决办法胶合板热压质量问题、产生原因及解决办法
Four, plywood hot pressing quality problems, causes and solutions of plywood hot pressing quality problems, causes and Solutions
产生缺陷: 1、胶合强度低或胶层脱胶
Defects: 1, low bonding strength or adhesive failure
原因:胶粘剂变质或浓度太低,或者胶的涂胶量太少;单板含水率过高或单板旋切质量差;涂胶单板涂胶后陈放时间过长;热压温度低,或热压压力小,或热压时间短。
The reason: Glue adhesive deterioration or concentration is too low, or few little amount of   glue sprayed to the veneer or the glue is too thin , veneer moisture content is too high or the poor quality of veneer; Glued veneer conditioning time is too long;  hot pressing temperature is too low ,  hot pressing pressure is not enough , or hot pressing time is too short  .
解决方法:及时检查胶粘剂的质量,不合格不用;根据单板的不同树种和不同厚度选择合适的涂胶量;在涂胶前检查芯板的含水率是否在要求的范围内;涂胶后板的陈放时间视气候条件而定;根据不同的产品选用合适的热压工艺,不要千篇一律用同样的热压参数。
Solution: check the quality of glue adhesive, unqualified can not be put into the production; The sprayed glue amount should be according to different wood species ,different quality and different thickness  of the core veneer ; Check if the Moisture content  before glue spraying /coating of the core veneer are  in the range of requirements; The glued veneer condition time should be  depending on the  climatic conditions; according to different plywood product selection of suitable  hot pressing process to decide the hot pressing parameter .
产生缺陷:2、“鼓泡”或局部开胶
Defects: 2, “bubble” or local delamination

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