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1、电晕处理机的发展历史标签: 软包装;电晕处理机;陶瓷电极;气隙;表面张力分类: 软包装技术 History of Development电晕处理技术的发展历史The configuration of the electrode has taken many forms. One of the earliest forms was a simple wire stretched parallel to the ground roll which was covered by a dielectric such as polyester wrapping. The wire electrode (

2、see Figure 10) accomplished its purpose, but provided such a narrow corona that the dwell time, the time which the substrate actually spent in the presence of corona, was exceedingly short. In addition, the power level that could be applied was extremely limited by the cross section capacity of the

3、wire and its ability to dissipate heat generated during treatment. Ozone, which is always produced in the corona-filled air gap, had to be removed from the work environment. (电晕处理机的)电极的构造有多种形式。其中最早期的一种形式是一根被张紧的电线与底辊相平行配置的形式,底辊上覆盖着绝缘物,例如聚酯。这种线型电极(参见图10)能够实现电晕处理的目的,但是它所提供的电火花过于狭窄,以至于处理时间-被处理的的基材在电火花中停

4、留的时间-非常短暂。另外,由于线型电极的截面容量(cross section capacity)较小,驱散在电晕处理过程中所产生的热量的能力较差,所以,该种电极所能输出的功率级是非常有限的。而且,必须将充斥在生产环境中的臭氧不断地排除出去,这些臭氧是在线型电极与底辊间的气隙间的电火花中不断地生成的。Another early form of electrode was a threaded rod which provided more dwell time, but because of the unevenness of the electrode surface, it had a te

5、ndency to create uneven treatment across the transverse of the substrate. Corona has a tendency to be more intensive at sharp points in the electrode (see Figure 11), causing higher treatment level where the threaded portion is closer to the substrate. 另一个早期的电极型式是螺线杆(threaded rod),它能够提供较长的处理时间(dwell

6、 time),但是,由于该电极的表面是不光滑的,所以,它有可能在基材的横截面上造成不均匀的处理效果。由于电火花往往集中在电极的尖端处(参见图11),因此,会在螺线杆与基材更接近的部位产生较高的处理水平(程度)。Straight metal bar electrodes were also used, and are still being used today. The bar produces even treatment across the substrate but requires a new electrode to be cut to length to match the we

7、b width each time the web is changed. This is inconvenient for the operator and requires a storage system for various lengths of electrode (see Figure 12). 直线型金属棒电极(Straight metal bar electrodes)也被使用过,而且今天仍然在应用中。该电极能够在基材的横断面上产生均匀的处理效果,但是,当基材的宽度发生变化时,就需要更换一根新的与基材宽度相匹配的电极。这对于操作者来说是不方便的,而且还需要事先储备不同长度的多

8、个电极(参见图12)。In order to overcome the need to cut electrodes to length, bar electrodes were cut in segments and mounted on a rod so that when web width changed, segments could be moved away from the ground roll, thus matching the electrode length to the web width (see Figure 13). Many such electrodes

9、are being used today. This configuration of electrodes has several advantages and disadvantages. 为了解决这一问题,直线型的金属棒电极被切割成许多小段,然后安装在一根金属杆上,这样一来,当基材的宽度变化时,其中的一些电极可以被从底辊表面移除,从而使电极的宽度与基材宽度相匹配(参见图13)。这种电极今天仍在被广泛使用。这种形式的电极有一些优点,也有一些缺点。When the segmented electrode was mounted directly above the ground roll,

10、the segments would swing out of the way when a wrinkle or splice greater than the air gap would pass over the ground roll and drop back into place when the wrinkle or splice had passed. Another advantage of the segmented electrode is the ability to raise center segments and allow strip treating. In

11、earlier electrodes, a thick splice striking the electrode could cause it to be damaged. A corresponding disadvantage is that ozone produced in the corona soon formed aluminum oxide deposits between the segments, thus causing them to remain in the nontreat position. This problem can be overcome to so

12、me extent by hardcoating or anodizing the segments. A further improvement is the use of stainless steel as the electrode material. This has virtually eliminated sticking of segments or warpage of the electrode. 当这种分段电极(segmented electrode)安装在底辊上后,如果基材上有大于气隙的皱褶或接头通过底辊时,分段电极就会摆离(swing out)底辊,而当皱褶或接头已经

13、通过底辊后,分段电极还会返回其原始位置。分段电极的另一个优点是可以将中间的电极升起,以便进行带状处理。在早期的分段电极中,过厚的接头有可能会造成电极的损坏。相应的缺点是:在电火花中产生的臭氧会生成氧化铝并沉积在分段电极间,导致分段电极不能返回其初始位置。这个问题可通过对分段电极进行表面硬化处理或阳极化处理得到某种程度的缓解。进一步的解决方法是使用不锈钢作为电极的加工材料。该方法事实上消除了分段电极间的粘连或电极的热变形的问题。A final drawback to this configuration is the possibility of uneven treatment across

14、the web. 这种电极型式的最大缺点是在基材的横断面上的处理程度的不均匀。A substrate having treatment that is not uniform across the web may cause bonding or heat-seal problems in printing, extrusion coating, coating, and laminating. Uneven treatment has been greatly alleviated by bias cutting of segments to prevent strip treating b

15、etween segments. 已经过电晕处理、但在横断面上处理程度不均匀的基材可能会在印刷、挤出涂布、表面涂层处理和复合加工中导致附着力、粘接强度和热封问题。通过对分段电极进行斜切处理(bias cutting)以防止电极间的带状处理,该问题已被极大地缓解了。The covered roll system using a dielectric covered roll with either a bar or segmented electrode alsopresented a size problem. In order to properly treat a given web wi

16、dth and dissipate heat generated during the treating process, the coated roll diameter must increase directly with the total applied power. Heat buildup on coated rolls is very destructive and can only be mitigated by increasing the roll diameter to allow a period of cooling between cyclic positioni

17、ng under the electrode. In addition, to provide ozone removal and operator safety, the station as a whole must also increase in size as the roll diameter increases. Figure 14 indicates roll diameter requirements as a function of applied power (kW). 包覆辊系统(the covered roll system, 绝缘体包覆的底辊,不管配备的是棒状电极还

18、是分段电极)都存在着尺寸问题。为了适当地处理给定宽度的基材,并驱散在处理过程中产生的热量,随着施加的能量的提高,包覆辊的直径必须增大。在包覆辊上的热量具有很大的破坏性,只能通过增加包覆辊的直径使之在周期性的处理过程中有一个冷却阶段才能得以缓解。另外,为了移除臭氧和操作者的安全,伴随着底辊直径的增加,电晕处理机的整体尺寸也需要增加。图14标示了包覆辊直径与电晕处理机功率(kW)的关系。 Another method which has been attempted without much success is to use several sets of segmented electrode

19、s which are staggered so that each row of segments covers the air gap from the previous row (see Figure 15). This solution has not proven reliable. Recent tests indicate that significant uneven treatment still occurs. 另一个曾经被应用过但不太成功的方法是使用交错排列的多套分段电极(参见图15)。这一方案的可靠性没有得到证实。近期的试验显示依然存在着值得注意的处理不均匀的状态。 T

20、wo early electrodes which were attempted involved a glass tube with a metal rod insert and a glass tube filled with steel wool (see Figure 16). This was an entirely new concept because, for the first time, the dielectric cover was removed from the ground roll and placed on the electrode. This early

21、bare-roll configuration promised a great many advantages but was soon abandoned because expansion of the metal rod, due to a rising temperature, broke the glass tube. Even when the electrode was rotated to spread the corona over a 360 degree revolution, neither overheating nor breakage was prevented

22、. 两个较早的不成功的电极系统,包括一个插入了金属棒的玻璃管和一个充填了钢丝棉的玻璃管(参见图16)。这在当时是一个全新的概念,因为它第一次从底辊上取消了绝缘覆盖物,并直接包覆在了电极上。这一较早的光辊(bare-roll)系统显示了许多的优点,但很快就被放弃了,因为随着温度的升高,金属棒膨胀,玻璃管就被胀破了!尽管曾将该玻璃电极旋转以分散电火花,但既不能防止过热也不能阻止玻璃管的破裂。Another serious consideration should be mentioned here. None of the metal electrodecovered-roll configura

23、tions work when treating conductive substrates such as foils or metallized film, and a very complex form of electrode was required (see Figure 17). 这里应该强调一下另一个重要的方法。当需要处理导电性的基材,例如铝箔或镀铝薄膜,时,没有一个金属电极包覆辊系统是可用的。此时,需要一个非常复杂的电极形式(参见图17)。This early bare-roll system consisted of a metal ground roll and a se

24、ries of dielectric covered electroderolls that were driven. This is a very expensive, cumbersome method of treating conductive substrates, but it was the only method available 这种早期的光辊系统(bare-roll system)由一个金属底辊和一组可主动旋转的绝缘体覆盖电极辊所组成。这是一个非常昂贵、非常复杂的处理导电性基材的方法,但在当时又是唯一可行的方法。In 1980, a new configuration o

25、f electrode capable of operating on a bare roll was developed which surmounted the basic problems that were experienced up to that point. This electrode achieved the following operational goals (also see Figure 18): 1980年,一个新的能够在光辊上操作的电极系统诞生了,它解决了在此之前所遇到的众多基础问题。这个电极达到了下列的操作目标(参见图18)。1. Even corona t

26、reatment across the transverse of the substrate. 在基材的横断面上的均匀的电晕处理效果。2. Eliminating the need to adjust the electrode to web width.去除了调整电极长度以适应基材宽度的需求。3. Eliminating the dielectric roll covering which required frequent replacement and entails an inventory of spare rolls as well as considerable product

27、ion loss during replacement of a burned-out roll.取消了绝缘辊包覆物,该包覆物需要不时地更换、需要有备件库存、以及在更新过程中难以估量的生产损失。4. Allow corona treatment of both conductive and nonconductive webs using a simple system without driven treater rolls. Further, even perforated webs can be treated with this type of electrode.可以使用这个没有主动

28、处理辊的简单系统处理导电性基材和绝缘性基材。甚至网孔状的基材也可以在这种类型的电极上进行处理。5. Allow splices to flow through the corona treating station without striking the electrode despite the close position of the electrode relative to the treater roll.In addition to achieving these operational goals, this new electrode configuration also

29、eliminated the need for a closed cabinet to remove ozone. Conventional corona treating systems require a closed cabinet not only to remove ozone in the operator area, but to prevent electrical shock to operators who are required to work in close proximity of the corona treating station. This recentl

30、y patented electrode assembly meets all the operational and safety requirements of extruders and converters (see Figure 19). 除了达到这些操作目标之外,这种新的电极系统也取消了用以去除臭氧的封闭式机壳。传统的电晕处理系统需要一个封闭式的机壳,不仅是为了去除臭氧,也是为了防止对操作者发生电击,因为操作者有时需要在接近电晕处理机的位置上进行工作。Substrates can even be selectively treated leaving specific areas

31、untreated as in the previously mentioned heat-seal applications (see Figure 20). The concept that made this electrode possible was the use of a rectangular ceramic tube filled with irregularly shaped aluminum alloy granules. 基材甚至可以被有选择性地进行处理,以在基材上留下特定的未处理区域,就象前面论述过的热封应用中(参见图20)。使得这种电极成为可能的理念是:在方形的陶瓷

32、管中填充入形态不规则的铝合金颗粒。When these granules heat up, they do not break the ceramic tube since there is sufficient room for their expansion. 当这些铝合金颗粒物被加热后,它们不会使陶瓷管破裂,因为在管内有足够空间供其膨胀。This electrode is accepted as the latest state-of-the-art in Europe as well as the United States. 这种电极在欧美被公认为是最完美的。Hundreds of

33、production lines use this type of system, which proved its ability to treat to high levels while providing long-term reliability. 成百上千的生产线使用了这一系统,它证实了其高水平的处理能力以及长期运行的可靠性。Why ceramic? It is a material which combines the attributes of dielectric strength with a high electrical power per square inch to

34、 enable high treatment levels. A ceramic was developed which allowed twice as much power per square inch to be applied to each electrode. The ceramic electrode achieved this higher treatment level because of its higher dielectric constant and lower electrical reactance. These factors allow the ceram

35、ic electrode to provide a higher treatment level for a given applied voltage. Furthermore, since ceramic is less sensitive to high operating temperatures, higher power levels can be applied and maintained to provide consistently higher levels of treatment per electrode. 为什么是陶瓷?因为它是这样一种材料:既有一定的绝缘强度的属

36、性,又有较高的单位面积电功率输出能力,使达到较高的电晕处理水平在技术上成为可能。陶瓷材料现已发展到这样的水平:使每支陶瓷电极每平方英寸可以输出的电能两倍于以前的电极材料。这种陶瓷材料能够达到这样高的处理水平是因为它具有较高的绝缘常数和较低的电阻。这些因素使得陶瓷电极能够在给定的电压条件下达到较高的处理水平。与此同时,陶瓷对高的操作温度较不敏感,因此,较高的功率水平才能够被输出,并且保持每支电极常态化的较高的处理水平。Any electrode, be it metal or ceramic, has a limit of effective output based upon the tota

37、l bar area of the electrode. In the past, bar area of a metal electrode was increased by cutting the face closest to the ground roll in a concentric curve to follow the roll face (see Figure 21).任何一种电极,不管是金属的或陶瓷的,基于它的总的电极表面积,都会有一个有效输出功率的限值。以前,增加金属电极棒的面积的方法是将电极朝向底辊的面加工成与底辊相同的同心圆(参见图21)。As more and mo

38、re power is applied to a given electrode, an ultimate limit is reached at which further power applied is wasted. Therefore, as power density requirements increased, corona treating systems required additional electrodes. The power capacity of the ceramic electrode reduces the number of electrodes by

39、 one-half, thus producing a smaller and less expensive station (see Figure 22). 随着给每一支电极施加的电能量的不断增加,输出功率的极限就达到了,此时再想增加输出电能的努力都是无用的。因此,随着功率密度需求的增加,电晕处理系统就需要增加电极数量。新的陶瓷电极功率输出能力将电极的数量减少了一半,这样就能生产出体积较小的和较便宜的电晕处理机了(参见图22)。Recent advances in dielectric roll coverings and power supply design have made hybr

40、id systems possible that greatly enhance the level of treatment on difficult to treat substrates. 近期在绝缘辊包覆材料和电源设计方面的进步使得随之而来的综合性电晕处理系统能够极大地强化在难处理基材上的处理水平。Ceramic electrodes with tightly controlled watt density and frequency can be operated over a treater roll coated with a special ceramic (see Figur

41、e 23). The result is an improved level of treatment on difficult to treat substrates such as cast film, polypropylene with high levels of slip additives, etc.具有严格控制的(tightly controlled)功率密度和频率的陶瓷电极可以应用在有特殊陶瓷涂层的处理底辊上(参见图23)。其结果是在诸如流涎膜、高爽滑剂含量的聚乙烯膜等难处理基材上实现了较好的处理水平。In bare-roll and “H” system treater s

42、tations, ceramic electrodes are attached in the assembly to allow removal and replacement in less than 10 minutes. This changeover time is critical when production loss and cost due to downtime can be measured in hundreds or thousands of dollars per hour. 在光辊(bare-roll)和如图23所示的“H”系统中,陶瓷电极的取出与更换可在10分

43、钟内完成。在停机损失或费用以每小时数百或数千美元计算的企业中,这么短的更换周期具有决定性的意义。Corona treating electrodes have come a long way from wire, to segmented metal, to specially formulated ceramic. Each time advancements are made, it would be wise to review what constitutes the ideal electrode. Some characteristics are described here: 电

44、晕处理电极已经走过了漫长的路程,经历了线型电极、分段电极、直到特殊的陶瓷电极。每一次取得进步时,回顾一下什么才是理想的电极是一件很有意义的事情。以下陈述了一些特征。1. The electrode must provide a controlled level of even treatment across the web. 电晕处理电极必须能提供可控的在基材横断面上均匀处理的能力。2. The electrode should provide treatment to both conductive or nonconductive webs.Figure 22. Ceramic Electrode. 电晕处理电极应能够处理导电性和绝缘性的基材(图22,陶瓷电极)。3. The

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