纸张长度变化的影响因素及注意事项
Influencing factors and precautions of paper length change
影响因素
influence factor
1.张力
1. Tension
张力即印刷过程中输纸系统对纸张的拉伸力，印刷过程中过大的张力会拉长纸张，印刷后消失张力，纸张必然回缩，使配页出现时长时短的问题，从而影响到配页。
Tension refers to the tensile force of the paper feeding system on the paper in the printing process. Excessive tension in the printing process will lengthen the paper. After printing, the tension will disappear, and the paper will inevitably retract, resulting in the problem of long and short time of page matching, which affects the page matching.
2.纸张含水量
2. Water content of paper
纸张含水量不同，也会造成纸张长度的变化。纸张含水量越大，印刷后纸张的收缩也就越严重。
The different moisture content of paper will also cause the change of paper length. The greater the water content of the paper, the more serious the shrinkage of the paper after printing.
3.纸张定量
3. Paper weight
在相同张力下，印刷所用纸张的定量越大(纸张越厚)，印刷后纸张的收缩严重，但也要考虑到厚纸含水量大的因素，一般情况下，厚纸应加大张力。
Under the same tension, the larger the quantity of paper used for printing (the thicker the paper), the serious shrinkage of paper after printing, but the factor of large water content of thick paper should also be considered. Generally, the tension of thick paper should be increased.
注意事项
matters needing attention
(1)印刷过程中，一种印品尽量使用相同、相同厚度的纸张，这样可以在印刷中使张力保持恒定。
(1) In the process of printing, paper of the same brand and thickness shall be used as much as possible for a printed matter, so that the tension can be kept constant during printing.
(2)实际生产中，即使使用相同、相同厚度的纸张，纸张含水量也有不同，要注意对其进行辨别。可用手触摸的方法，一般含水量大的纸张发凉、发涩;相同宽度、和蔗的纸张，含水量大的会重一些，因此要适当减小张力。但要注意纸张适性，可以把纸张在生产车间多放置一段时间，以适应车间的温、湿度，从而解决纸张含水量问题。
(2) In actual production, even if the paper of the same brand and thickness is used, the water content of the paper is different, so we should pay attention to distinguish it. It can be touched by hand. Generally, the paper with large water content is cold and astringent; The paper with the same width, and sugarcane will be heavier if the water content is large, so the tension should be reduced appropriately. However, we should pay attention to the suitability of the paper. The paper can be placed in the production workshop for a period of time to adapt to the temperature and humidity of the workshop, so as to solve the problem of paper water content.
(3)遇到不同定量或不同品种纸张的多联单，更应注意张力的调整。一，在印刷一联时，用3m以上孔距尺测量，并比标准长度放出2~4mm,以弥补因失水而引起的纸张收缩;二，在印刷二联时，也需用3m孔距尺对纸张孔距进行测量，如该联纸张较厚，则可比标准长度多放出1~2mm,纸张含水高，收缩系统数大。如此将联都根据纸张厚薄在孔距上给予不同的加放量，使配页时每联纸张都能保持基本一致。
(3) In case of multiple sheets with different quantities or different varieties of paper, pay more attention to the adjustment of tension. 1、 When printing a copy, measure with a hole spacing ruler of more than 3m and release 2 ~ 4mm compared with the standard length to make up for the paper shrinkage caused by water loss; 2、 When printing two sheets, a 3M hole pitch ruler is also required to measure the paper hole pitch. If the sheet is thicker, it can be released 1 ~ 2mm more than the standard length, with high water content and large number of shrinkage systems. In this way, different addition amounts are given to the hole spacing according to the thickness of the paper, so that the paper of each page can be basically consistent during page matching.
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