2011年3月31日 星期四
Datok Tan TIONG HONG will be remembered by us forever.
My deepest condolences to the family of Datok Tan Tiong Hong, the former deputy educational minister , deputy finiance minister,is a good examole to young people, despite being key person in many organisation , he remain humble and keen to help people. I am proud of him as a member of MCA , because he is willing to share his knowlege and experience and always encourage the grassroot to improve. Datok Tan TIONG HONG will be remembered by us forever.
2009年10月26日 星期一
垂直農場
前沿> 2007年9月23日 作者:xwz2367609 [返回]
垂直农场”：在摩天大楼里种地
垂直农场”：在摩天大楼里种地
--------------------------------------------------------------------------------
2007年08月05日 深圳特区报
“垂直农场”：在摩天大楼里种地
一座30层楼高的农场能为5万人提供一年的粮食和饮用水，这样的环保农场不会产生任何废物，建造一座“垂直农场”需要数十亿美元
面对日趋严重的全球气候变暖问题及城市人口剧增之势，一位美国科学家提出了大胆的设想：把摩天大楼开辟成农场！这样，既可以为数百万人提供饮食所需，又能利用植物光合作用，吸收二氧化碳，从而达到给地球降温的目的，这不失为是一举两得的好办法。然而，这种看似不切合实际的想法果真能够变成现实吗？
改变传统种地方式遏制环境恶化
美国前副总统戈尔在其担任制片人的纪录片《难以忽视的真相》中呼吁每一个人都来植树造林。但是，现年67岁哥伦比亚大学微生物学家迪克森·德斯波米尔（Dickson Despommier）认为，为满足急剧增长的人口的需要，地球上越来越多的森林正变成耕地，倘若真如科学家所建议的那样，我们又能到哪里去植树？一方面，现在地球上近41％的土地用于农业，另一方面，人口却在不断地急速增长，估计到2050年会从今天的67亿人增至92亿人，而绝大多数人生活在熙熙攘攘的城市。
专家认为，面对全球变暖趋势，只有植树造林才能遏制这种不利局面。德斯波米尔强调，如今唯一能为吸收二氧化碳的树林腾出空间的方法就是改变我们种地的方式。他还想像了这样一幅图画：将世界上最大一些城市变成“垂直农场”，每座农场有30层楼高，能为5万人供应一年的饮水粮食所需，重要的是，不会产生任何废物。
德斯波米尔目前正在同潜在投资者们研讨建设第一座“垂直农场”示范园一事。另外，他还是美国曼哈顿环保工程公司“纽约太阳能利用”（NewYorkSunWorks）的董事会成员，该公司曾于今年5月在一个钻井浮船上展示了类似的城市农场概念。
高科技农业与新建筑技术相结合
城市农场向来被看作是唐吉诃德式的付出。从栖息于纽约上西区（著名文化人居住社区）公寓楼顶的小畜牧场到受到房地产开发威胁的社区公园，在城市中保留一点乡村气息的梦想在很多人看来就是乌托邦式的梦想。美国哥伦比亚大学环境学教授和微生物学家迪克森·德斯波米尔的梦想相信让很多人望尘莫及，他认为在摩天大楼建设“垂直农场”有助于抑制全球变暖趋势。
可以想像一下这样的情景：纽约总督岛30层的摩天大楼一边生产水果、蔬菜和谷物，一边还能产生清洁能源，净化污水。据德斯波米尔估计，约150栋此类建筑物便能供应纽约全市一年的饮食所需。利用现有的绿色建筑系统，垂直农场不仅能实现自给自足，还能为城市居民提供新鲜食品，净化城市环境。
德斯波米尔于6年前提出了垂直农场概念，并同对建设“城市可持续农业发展中心”感兴趣的荷兰、迪拜等地的科学家和风险投资家签署了合作协议。据他估计，若想将高科技农业实验同最新建筑技术完美结合起来，需要农业经济学家、建筑师、工程师、农艺学家和城市规划者用5到10年时间来解决这个问题。
“垂直农场”使退耕还林成为可能
垂直农场怎样才能遏制气候变化？德斯波米尔教授认为，唯一的办法就是将地球大部分土地“退耕还林”，这样才有机会使气候模式稳定下来。减少能源消耗则是抑制全球变暖趋势的上上策，这也是美国前总统最近提交给国会一项提议的中心内容。他表示，在目前用于耕地的土地上植树造林，会降低二氧化碳向大气的排放量，取得的成果同采用能效更高的节能方式相同。
发展室内农业还有另外一个原因：世界人口急剧增长。据人口统计学家估计，到2050年，全球总人口将比现在多出30亿人，达到92亿人。如果继续维持现有的农业发展模式，那么只能把相当于巴西国土面积的土地开辟成耕地，才能养活多增加的几亿人口。然而，现在地球上几乎所有能生产粮食的土地已经变成耕地，这还是在没有考虑到因全球气候变暖导致海平面上升而淹没更多陆地的前提下。
根据播种的农作物类型，一个垂直农场也许能够把数千英亩农田永远地变成树林。眼下，这些估算很大程度上还只是一种推测，不过一个现实案例可以让我们一窥垂直农场未来发展的前景：在佛罗里达州的一块种草莓的农场被“安德鲁”飓风夷为平地之后，农场主将其变为一个水培农场。他们在室内和大楼每一层顶部种植草莓，如今，一英亩地的产量相当于过去30英亩土地的产量。
在摩天大楼里办农场好处多多
为什么要在城市中建设垂直农场呢？专家指出，在可控环境下种植农作物有诸多好处：第一，城市中没有家畜，因此不会通过未经处理的废物传播疾病；第二，不会因天灾造成农作物大规模歉收；第三，“无赖”转基因品种进入“天然”植物世界的可能性微乎其微。所有农作物都可以通过有机栽培方式生长，不会使用除草剂、杀虫剂或农药，从而没了有害的农业废物。到2050年，全球80％的人口将居住在城市。另外，城市已经拥有建设垂直农场所需的密度和基础设施，而“超绿色”摩天大楼不仅生产粮食，还能供应能源，创造真正意义上的自给自足的环境。
像美国亚利桑那州的“生物圈2号”项目一样，真正的垂直农场也许需要腰缠万贯的乌托邦式慈善家的鼎力支持。比如像美国得克萨斯州石油大王爱德华·巴斯这样的人。上世纪80年代，巴斯个人出资2亿美元，在美国亚利桑那州图森市以北的沙漠中建起了“生物圈2号”实验基地。这个基地占地1.3万平方米，仿佛一个巨大的温室，雨林、沙漠、草原和海洋应有尽有。
在当今社会，建设一个更小、更简单的垂直农场可能也需要2亿美元，据悉，来自耕地供应不足的地方的富翁也许会提供这笔建设资金，如日本、冰岛，迪拜的可能性最大。德斯波米尔教授相信，第一个垂直农场将在15年内建成，不过颇具讽刺意味的是，建设垂直农场的资金很有可能就来自于销售石油所得。
5到10年内建示范园
—“垂直农场”设计师德斯波米尔访谈录
问：你怎么会想到在摩天大楼上建设农场呢？
答：大概8年前，我要求我的学生研究有关城市可持续发展的诸多方案，他们提出在曼哈顿的商业大厦屋顶建设13英亩的可耕地。根据我们的推算，它能养活这座城市2％的人口。于是我说，“让我们充分利用曼哈顿1723栋遭废弃的建筑吧，对其进行改进，接着采用水耕法，将它们一个个变成农场。我又说，‘我们暂且不要考虑资金、空间和时间，先来设计一栋可以向5万人供应一年饮水粮食所需的大楼吧。’”
问：这意味着水来自于植物吗？
答：是的。浓缩液来自于植物叶子，即使你将水输送到屋顶。如果拥有相当于一个城区规模的垂直农场，那么里面的植物能产生足够5万人需要的饮用水。
问：灌溉用水来自于哪里？
答：污水，首先，清除污水中的泥渣。接着，让它在不可食用的植物和饲养斑马贝的塔楼内（最好的有机物过滤系统）中反复过滤。在完成这几个步骤之后，水就会变得干净了。
问：你能在摩天大楼内种植多少种水果和蔬菜？
答：超过100种，如草莓、蓝莓，甚至微型香蕉。我们从宇航局那里得到了能在室内生长的植物名单。原来，宇航局拥有一个庞大的水耕法项目，因为火星上可没有外卖——你不能派人去取比萨饼。遗传工程和人工选择还将在垂直农场发挥重要作用，因为有很多植物我们尚不知道如何在室内生长，如传统玉米。
问：这种方法怎样抑制全球变暖趋势？
答：所有政府报告不约而同指出一件事：传统农业也是一个严重的污染源。我很喜欢看一望无际的麦田，但这种污染也是在城市之外种植粮食的一大代价——地球上40.5％的土地都用于农业生产。随着人口剧增，对粮食的需求自然会上升，这当然需要开辟更多土地用于耕种。因此，必须找到替代传统农业的方法。我们已经拥有吸收二氧化碳的良策——植树造林。
问：建设垂直农场的成本高吗？
答：第一座垂直农场可能需要数十亿美元。我计划给它注入各种高科技元素：植物将被放到自动输送带上，这样，就可以源源不断地带来植物生长所需的光线，让营养液输送系统实现自动化。当然，政府应该向第一座垂直农场提供补助和减税等激励措施。我们正在讨论的项目的重要性可不亚于开发“土星”火箭啊。
问：第一座垂直农场何时能建成？
答：一旦得到了资金支持，我们能在5到10年内建设一个示范园。我希望自己能活到106岁，那样的话，到时就能看到地平线上到处都是垂直农场了。
垂直农场横切面
①农作物 收割器使用电子眼监控水果和蔬菜生长情况，检验农作物是否成熟。
②麦田 空间利用最大化十分关键，所以，在此图中，我们看到上下两层都种农作物。
③水池 灌溉剩下的废水在此处收集，通过水管流向过滤系统。
④输送装置 将适量的水和光线分别输送到最需要它们的农作物中。
垂直农场结构图
①太阳能电池板 垂直农场所需大部分能量由颗粒发电系统供应。这个太阳能电池板可跟着太阳方向旋转，驱动内部制冷系统运行，在阳光最强烈时，制冷系统的使用达到最大化。
②风力螺旋叶 这是对太阳能发电的一种替代或补充，这是美国克利夫兰州立大学工程学教授的创意。常规风车太大，不太适合城市使用。风力螺旋叶能像螺旋桨一样通过小叶片驱动空气向上流动。
③玻璃板 由钛氧化物制成的清洁涂层，可收集污染物，防止雨珠溅落到地面；雨水流到玻璃下，同时使光线效果达到最大化，还能清洁污染物。水槽可收集雨水，进行过滤。
④主控室 从这里可以调节垂直农场的环境，使其全年365天不间断地种植、收割庄稼。
⑤建筑设计 设计灵感源自好莱坞Capitol唱片公司总部。圆形循环设计使空间利用实现最大化，同时最大程度地让阳光进入大厦。模块式楼层像筹码一样堆叠起来，弹性更强。
⑥农作物生产 垂直农场不仅可以种植水果蔬菜，还能养鱼、养猪和家禽。据德斯波米尔估计，一个垂直农场足够5万人一年的饮食所需。
颗粒发电系统
垂直农场的另外一个电力来源是将不可食用的植物颗粒（如玉米麸皮）变成燃料。
将植物废料输入颗粒发电系统①，植物废料先是被加工成粉末状②，接着压缩成可全部烧掉的燃料颗粒③，最后变成水蒸气④。北美60多个颗粒制造工厂每年可生产60万吨燃料；美国爱达荷州一片占地3400平方英尺的住宅就利用颗粒来满足自身电力需要。
图：夜幕中的“垂直农场”。专家估计，约150栋此类建筑物便能供应纽约全市一年的饮食所需。
本版撰文任秋凌
垂直农场”：在摩天大楼里种地
垂直农场”：在摩天大楼里种地
--------------------------------------------------------------------------------
2007年08月05日 深圳特区报
“垂直农场”：在摩天大楼里种地
一座30层楼高的农场能为5万人提供一年的粮食和饮用水，这样的环保农场不会产生任何废物，建造一座“垂直农场”需要数十亿美元
面对日趋严重的全球气候变暖问题及城市人口剧增之势，一位美国科学家提出了大胆的设想：把摩天大楼开辟成农场！这样，既可以为数百万人提供饮食所需，又能利用植物光合作用，吸收二氧化碳，从而达到给地球降温的目的，这不失为是一举两得的好办法。然而，这种看似不切合实际的想法果真能够变成现实吗？
改变传统种地方式遏制环境恶化
美国前副总统戈尔在其担任制片人的纪录片《难以忽视的真相》中呼吁每一个人都来植树造林。但是，现年67岁哥伦比亚大学微生物学家迪克森·德斯波米尔（Dickson Despommier）认为，为满足急剧增长的人口的需要，地球上越来越多的森林正变成耕地，倘若真如科学家所建议的那样，我们又能到哪里去植树？一方面，现在地球上近41％的土地用于农业，另一方面，人口却在不断地急速增长，估计到2050年会从今天的67亿人增至92亿人，而绝大多数人生活在熙熙攘攘的城市。
专家认为，面对全球变暖趋势，只有植树造林才能遏制这种不利局面。德斯波米尔强调，如今唯一能为吸收二氧化碳的树林腾出空间的方法就是改变我们种地的方式。他还想像了这样一幅图画：将世界上最大一些城市变成“垂直农场”，每座农场有30层楼高，能为5万人供应一年的饮水粮食所需，重要的是，不会产生任何废物。
德斯波米尔目前正在同潜在投资者们研讨建设第一座“垂直农场”示范园一事。另外，他还是美国曼哈顿环保工程公司“纽约太阳能利用”（NewYorkSunWorks）的董事会成员，该公司曾于今年5月在一个钻井浮船上展示了类似的城市农场概念。
高科技农业与新建筑技术相结合
城市农场向来被看作是唐吉诃德式的付出。从栖息于纽约上西区（著名文化人居住社区）公寓楼顶的小畜牧场到受到房地产开发威胁的社区公园，在城市中保留一点乡村气息的梦想在很多人看来就是乌托邦式的梦想。美国哥伦比亚大学环境学教授和微生物学家迪克森·德斯波米尔的梦想相信让很多人望尘莫及，他认为在摩天大楼建设“垂直农场”有助于抑制全球变暖趋势。
可以想像一下这样的情景：纽约总督岛30层的摩天大楼一边生产水果、蔬菜和谷物，一边还能产生清洁能源，净化污水。据德斯波米尔估计，约150栋此类建筑物便能供应纽约全市一年的饮食所需。利用现有的绿色建筑系统，垂直农场不仅能实现自给自足，还能为城市居民提供新鲜食品，净化城市环境。
德斯波米尔于6年前提出了垂直农场概念，并同对建设“城市可持续农业发展中心”感兴趣的荷兰、迪拜等地的科学家和风险投资家签署了合作协议。据他估计，若想将高科技农业实验同最新建筑技术完美结合起来，需要农业经济学家、建筑师、工程师、农艺学家和城市规划者用5到10年时间来解决这个问题。
“垂直农场”使退耕还林成为可能
垂直农场怎样才能遏制气候变化？德斯波米尔教授认为，唯一的办法就是将地球大部分土地“退耕还林”，这样才有机会使气候模式稳定下来。减少能源消耗则是抑制全球变暖趋势的上上策，这也是美国前总统最近提交给国会一项提议的中心内容。他表示，在目前用于耕地的土地上植树造林，会降低二氧化碳向大气的排放量，取得的成果同采用能效更高的节能方式相同。
发展室内农业还有另外一个原因：世界人口急剧增长。据人口统计学家估计，到2050年，全球总人口将比现在多出30亿人，达到92亿人。如果继续维持现有的农业发展模式，那么只能把相当于巴西国土面积的土地开辟成耕地，才能养活多增加的几亿人口。然而，现在地球上几乎所有能生产粮食的土地已经变成耕地，这还是在没有考虑到因全球气候变暖导致海平面上升而淹没更多陆地的前提下。
根据播种的农作物类型，一个垂直农场也许能够把数千英亩农田永远地变成树林。眼下，这些估算很大程度上还只是一种推测，不过一个现实案例可以让我们一窥垂直农场未来发展的前景：在佛罗里达州的一块种草莓的农场被“安德鲁”飓风夷为平地之后，农场主将其变为一个水培农场。他们在室内和大楼每一层顶部种植草莓，如今，一英亩地的产量相当于过去30英亩土地的产量。
在摩天大楼里办农场好处多多
为什么要在城市中建设垂直农场呢？专家指出，在可控环境下种植农作物有诸多好处：第一，城市中没有家畜，因此不会通过未经处理的废物传播疾病；第二，不会因天灾造成农作物大规模歉收；第三，“无赖”转基因品种进入“天然”植物世界的可能性微乎其微。所有农作物都可以通过有机栽培方式生长，不会使用除草剂、杀虫剂或农药，从而没了有害的农业废物。到2050年，全球80％的人口将居住在城市。另外，城市已经拥有建设垂直农场所需的密度和基础设施，而“超绿色”摩天大楼不仅生产粮食，还能供应能源，创造真正意义上的自给自足的环境。
像美国亚利桑那州的“生物圈2号”项目一样，真正的垂直农场也许需要腰缠万贯的乌托邦式慈善家的鼎力支持。比如像美国得克萨斯州石油大王爱德华·巴斯这样的人。上世纪80年代，巴斯个人出资2亿美元，在美国亚利桑那州图森市以北的沙漠中建起了“生物圈2号”实验基地。这个基地占地1.3万平方米，仿佛一个巨大的温室，雨林、沙漠、草原和海洋应有尽有。
在当今社会，建设一个更小、更简单的垂直农场可能也需要2亿美元，据悉，来自耕地供应不足的地方的富翁也许会提供这笔建设资金，如日本、冰岛，迪拜的可能性最大。德斯波米尔教授相信，第一个垂直农场将在15年内建成，不过颇具讽刺意味的是，建设垂直农场的资金很有可能就来自于销售石油所得。
5到10年内建示范园
—“垂直农场”设计师德斯波米尔访谈录
问：你怎么会想到在摩天大楼上建设农场呢？
答：大概8年前，我要求我的学生研究有关城市可持续发展的诸多方案，他们提出在曼哈顿的商业大厦屋顶建设13英亩的可耕地。根据我们的推算，它能养活这座城市2％的人口。于是我说，“让我们充分利用曼哈顿1723栋遭废弃的建筑吧，对其进行改进，接着采用水耕法，将它们一个个变成农场。我又说，‘我们暂且不要考虑资金、空间和时间，先来设计一栋可以向5万人供应一年饮水粮食所需的大楼吧。’”
问：这意味着水来自于植物吗？
答：是的。浓缩液来自于植物叶子，即使你将水输送到屋顶。如果拥有相当于一个城区规模的垂直农场，那么里面的植物能产生足够5万人需要的饮用水。
问：灌溉用水来自于哪里？
答：污水，首先，清除污水中的泥渣。接着，让它在不可食用的植物和饲养斑马贝的塔楼内（最好的有机物过滤系统）中反复过滤。在完成这几个步骤之后，水就会变得干净了。
问：你能在摩天大楼内种植多少种水果和蔬菜？
答：超过100种，如草莓、蓝莓，甚至微型香蕉。我们从宇航局那里得到了能在室内生长的植物名单。原来，宇航局拥有一个庞大的水耕法项目，因为火星上可没有外卖——你不能派人去取比萨饼。遗传工程和人工选择还将在垂直农场发挥重要作用，因为有很多植物我们尚不知道如何在室内生长，如传统玉米。
问：这种方法怎样抑制全球变暖趋势？
答：所有政府报告不约而同指出一件事：传统农业也是一个严重的污染源。我很喜欢看一望无际的麦田，但这种污染也是在城市之外种植粮食的一大代价——地球上40.5％的土地都用于农业生产。随着人口剧增，对粮食的需求自然会上升，这当然需要开辟更多土地用于耕种。因此，必须找到替代传统农业的方法。我们已经拥有吸收二氧化碳的良策——植树造林。
问：建设垂直农场的成本高吗？
答：第一座垂直农场可能需要数十亿美元。我计划给它注入各种高科技元素：植物将被放到自动输送带上，这样，就可以源源不断地带来植物生长所需的光线，让营养液输送系统实现自动化。当然，政府应该向第一座垂直农场提供补助和减税等激励措施。我们正在讨论的项目的重要性可不亚于开发“土星”火箭啊。
问：第一座垂直农场何时能建成？
答：一旦得到了资金支持，我们能在5到10年内建设一个示范园。我希望自己能活到106岁，那样的话，到时就能看到地平线上到处都是垂直农场了。
垂直农场横切面
①农作物 收割器使用电子眼监控水果和蔬菜生长情况，检验农作物是否成熟。
②麦田 空间利用最大化十分关键，所以，在此图中，我们看到上下两层都种农作物。
③水池 灌溉剩下的废水在此处收集，通过水管流向过滤系统。
④输送装置 将适量的水和光线分别输送到最需要它们的农作物中。
垂直农场结构图
①太阳能电池板 垂直农场所需大部分能量由颗粒发电系统供应。这个太阳能电池板可跟着太阳方向旋转，驱动内部制冷系统运行，在阳光最强烈时，制冷系统的使用达到最大化。
②风力螺旋叶 这是对太阳能发电的一种替代或补充，这是美国克利夫兰州立大学工程学教授的创意。常规风车太大，不太适合城市使用。风力螺旋叶能像螺旋桨一样通过小叶片驱动空气向上流动。
③玻璃板 由钛氧化物制成的清洁涂层，可收集污染物，防止雨珠溅落到地面；雨水流到玻璃下，同时使光线效果达到最大化，还能清洁污染物。水槽可收集雨水，进行过滤。
④主控室 从这里可以调节垂直农场的环境，使其全年365天不间断地种植、收割庄稼。
⑤建筑设计 设计灵感源自好莱坞Capitol唱片公司总部。圆形循环设计使空间利用实现最大化，同时最大程度地让阳光进入大厦。模块式楼层像筹码一样堆叠起来，弹性更强。
⑥农作物生产 垂直农场不仅可以种植水果蔬菜，还能养鱼、养猪和家禽。据德斯波米尔估计，一个垂直农场足够5万人一年的饮食所需。
颗粒发电系统
垂直农场的另外一个电力来源是将不可食用的植物颗粒（如玉米麸皮）变成燃料。
将植物废料输入颗粒发电系统①，植物废料先是被加工成粉末状②，接着压缩成可全部烧掉的燃料颗粒③，最后变成水蒸气④。北美60多个颗粒制造工厂每年可生产60万吨燃料；美国爱达荷州一片占地3400平方英尺的住宅就利用颗粒来满足自身电力需要。
图：夜幕中的“垂直农场”。专家估计，约150栋此类建筑物便能供应纽约全市一年的饮食所需。
本版撰文任秋凌
2009年9月13日 星期日
預防電路故障所引起的意外
預防電路故障所引起的意外
筆者對電路裝置有一些經驗，因此想打開話題，拋磚引玉，希望更多有識之士能參與討論，對預防電路故障
所引起的意外之外給予他們保貴的意見。筆者也希望有全国各地的地方政府，消防局，國家能源公司，馬來
西亞工程師協會(Institue of Engineer Malaysia)，馬來西亞工程局(Board of Engineer Malaysia)
朝野政黨，各民間團體如中小型工業協會,居民协会，睦邻原则中心及非政府組織能夠關注这一项课题。在我
國有很多舊房子的電路裝置及配備是不符合標準的。我不清楚國家能源公司及各地方政府有采取任何措施来
改进这种情况。
最近在吉隆坡發生的一起火災使超過百戶的居民無家可歸而且還奪取了兩位生命。據報導這起火災的造成是
因為使用不符合標準的保險絲。（ＦＵＳＥ）．
除了保險絲。（ＦＵＳＥ）被用于預防電路故障所引起的意外之外，一般家里的電源接受控制箱(Power
Supply Intake Point)，也置有預防電流超荷的電路切斷器(Circuit Breaker)及置有防止漏電的的電路切
斷器（Earth Leakage Circuit breaker). 。選擇電路切斷器时有需考量到電流的消費量及配線的直徑。也就是說
電流消費量大， 就必須用更大直徑的配線，所使用的電路切斷器是属于高電流型的。因此家里使用的電路
切斷器，保險絲，配线必須根據標準，假如使用的電路切斷器或保險絲沒有根據標準會引起種種的故障。如
果電路切斷器或保險絲的切斷值少過標準值就可能引起電流不斷中斷。如果電路切斷器或保險絲的切斷值超
過標準值，就會因為電路切斷器在电流超荷（Current overloading）时无法操作不能切斷电路 而使到電流密度
(Current Density)過高而引起銅制的導电體熱能大量增加，温度大量提高，而使到PVC制的絕緣层(Insulation
Layer) 燃烧最終導致火患。
短路也是造成火患的其中原因之一，所谓短路是指配线(cable)中的銅制的導电體与另一導电體接触而使到电
阻大幅降低，电流大幅增加而引起的火患。 造成短路的其中两大原因是1）絕緣层被老鼠咬破，2）配线长
期受到日晒雨打，化学物的腐蚀。
根據我國的相關法律有规定每一間新建的建筑物的電路必須由合格的電氣承包商裝備，才能夠獲得入伙紙。
雖然我國有明文規定的法律來防止電路故障所引起的火患，但單單靠法律來防止電路故障所引起的火患是不
夠。我們也應該教育公眾如何防止電路故障所引起的火患。在這方面我相信，國家能源公司，市政局，馬來
西亞工程師協會 消防局應扮演更重要，更積極的角色。
電路故障所引起的意外可造成财物己人命的损失，因此我们立刻采取有效的措施以預防電路故障所引起的意
外。
筆者對電路裝置有一些經驗，因此想打開話題，拋磚引玉，希望更多有識之士能參與討論，對預防電路故障
所引起的意外之外給予他們保貴的意見。筆者也希望有全国各地的地方政府，消防局，國家能源公司，馬來
西亞工程師協會(Institue of Engineer Malaysia)，馬來西亞工程局(Board of Engineer Malaysia)
朝野政黨，各民間團體如中小型工業協會,居民协会，睦邻原则中心及非政府組織能夠關注这一项课题。在我
國有很多舊房子的電路裝置及配備是不符合標準的。我不清楚國家能源公司及各地方政府有采取任何措施来
改进这种情况。
最近在吉隆坡發生的一起火災使超過百戶的居民無家可歸而且還奪取了兩位生命。據報導這起火災的造成是
因為使用不符合標準的保險絲。（ＦＵＳＥ）．
除了保險絲。（ＦＵＳＥ）被用于預防電路故障所引起的意外之外，一般家里的電源接受控制箱(Power
Supply Intake Point)，也置有預防電流超荷的電路切斷器(Circuit Breaker)及置有防止漏電的的電路切
斷器（Earth Leakage Circuit breaker). 。選擇電路切斷器时有需考量到電流的消費量及配線的直徑。也就是說
電流消費量大， 就必須用更大直徑的配線，所使用的電路切斷器是属于高電流型的。因此家里使用的電路
切斷器，保險絲，配线必須根據標準，假如使用的電路切斷器或保險絲沒有根據標準會引起種種的故障。如
果電路切斷器或保險絲的切斷值少過標準值就可能引起電流不斷中斷。如果電路切斷器或保險絲的切斷值超
過標準值，就會因為電路切斷器在电流超荷（Current overloading）时无法操作不能切斷电路 而使到電流密度
(Current Density)過高而引起銅制的導电體熱能大量增加，温度大量提高，而使到PVC制的絕緣层(Insulation
Layer) 燃烧最終導致火患。
短路也是造成火患的其中原因之一，所谓短路是指配线(cable)中的銅制的導电體与另一導电體接触而使到电
阻大幅降低，电流大幅增加而引起的火患。 造成短路的其中两大原因是1）絕緣层被老鼠咬破，2）配线长
期受到日晒雨打，化学物的腐蚀。
根據我國的相關法律有规定每一間新建的建筑物的電路必須由合格的電氣承包商裝備，才能夠獲得入伙紙。
雖然我國有明文規定的法律來防止電路故障所引起的火患，但單單靠法律來防止電路故障所引起的火患是不
夠。我們也應該教育公眾如何防止電路故障所引起的火患。在這方面我相信，國家能源公司，市政局，馬來
西亞工程師協會 消防局應扮演更重要，更積極的角色。
電路故障所引起的意外可造成财物己人命的损失，因此我们立刻采取有效的措施以預防電路故障所引起的意
外。
預防電路故障所引起的意外
預防電路故障所引起的意外
筆者對電路裝置有一些經驗，因此想打開話題，拋磚引玉，希望更多有識之士能參與討論，對預防電路故障
所引起的意外之外給予他們保貴的意見。筆者也希望有全国各地的地方政府，消防局，國家能源公司，馬來
西亞工程師協會(Institue of Engineer Malaysia)，馬來西亞工程局(Board of Engineer Malaysia)
朝野政黨，各民間團體如中小型工業協會,居民协会，睦邻原则中心及非政府組織能夠關注这一项课题。在我
國有很多舊房子的電路裝置及配備是不符合標準的。我不清楚國家能源公司及各地方政府有采取任何措施来
改进这种情况。
最近在吉隆坡發生的一起火災使超過百戶的居民無家可歸而且還奪取了兩位生命。據報導這起火災的造成是
因為使用不符合標準的保險絲。（ＦＵＳＥ）．
除了保險絲。（ＦＵＳＥ）被用于預防電路故障所引起的意外之外，一般家里的電源接受控制箱(Power
Supply Intake Point)，也置有預防電流超荷的電路切斷器(Circuit Breaker)及置有防止漏電的的電路切
斷器（Earth Leakage Circuit breaker). 。選擇電路切斷器时有需考量到電流的消費量及配線的直徑。也就是說
電流消費量大， 就必須用更大直徑的配線，所使用的電路切斷器是属于高電流型的。因此家里使用的電路
切斷器，保險絲，配线必須根據標準，假如使用的電路切斷器或保險絲沒有根據標準會引起種種的故障。如
果電路切斷器或保險絲的切斷值少過標準值就可能引起電流不斷中斷。如果電路切斷器或保險絲的切斷值超
過標準值，就會因為電路切斷器在电流超荷（Current overloading）时无法操作不能切斷电路 而使到電流密度
(Current Density)過高而引起銅制的導电體熱能大量增加，温度大量提高，而使到PVC制的絕緣层(Insulation
Layer) 燃烧最終導致火患。
短路也是造成火患的其中原因之一，所谓短路是指配线(cable)中的銅制的導电體与另一導电體接触而使到电
阻大幅降低，电流大幅增加而引起的火患。 造成短路的其中两大原因是1）絕緣层被老鼠咬破，2）配线长
期受到日晒雨打，化学物的腐蚀。
根據我國的相關法律有规定每一間新建的建筑物的電路必須由合格的電氣承包商裝備，才能夠獲得入伙紙。
雖然我國有明文規定的法律來防止電路故障所引起的火患，但單單靠法律來防止電路故障所引起的火患是不
夠。我們也應該教育公眾如何防止電路故障所引起的火患。在這方面我相信，國家能源公司，市政局，馬來
西亞工程師協會 消防局應扮演更重要，更積極的角色。
電路故障所引起的意外可造成财物己人命的损失，因此我们立刻采取有效的措施以預防電路故障所引起的意
外。
筆者對電路裝置有一些經驗，因此想打開話題，拋磚引玉，希望更多有識之士能參與討論，對預防電路故障
所引起的意外之外給予他們保貴的意見。筆者也希望有全国各地的地方政府，消防局，國家能源公司，馬來
西亞工程師協會(Institue of Engineer Malaysia)，馬來西亞工程局(Board of Engineer Malaysia)
朝野政黨，各民間團體如中小型工業協會,居民协会，睦邻原则中心及非政府組織能夠關注这一项课题。在我
國有很多舊房子的電路裝置及配備是不符合標準的。我不清楚國家能源公司及各地方政府有采取任何措施来
改进这种情况。
最近在吉隆坡發生的一起火災使超過百戶的居民無家可歸而且還奪取了兩位生命。據報導這起火災的造成是
因為使用不符合標準的保險絲。（ＦＵＳＥ）．
除了保險絲。（ＦＵＳＥ）被用于預防電路故障所引起的意外之外，一般家里的電源接受控制箱(Power
Supply Intake Point)，也置有預防電流超荷的電路切斷器(Circuit Breaker)及置有防止漏電的的電路切
斷器（Earth Leakage Circuit breaker). 。選擇電路切斷器时有需考量到電流的消費量及配線的直徑。也就是說
電流消費量大， 就必須用更大直徑的配線，所使用的電路切斷器是属于高電流型的。因此家里使用的電路
切斷器，保險絲，配线必須根據標準，假如使用的電路切斷器或保險絲沒有根據標準會引起種種的故障。如
果電路切斷器或保險絲的切斷值少過標準值就可能引起電流不斷中斷。如果電路切斷器或保險絲的切斷值超
過標準值，就會因為電路切斷器在电流超荷（Current overloading）时无法操作不能切斷电路 而使到電流密度
(Current Density)過高而引起銅制的導电體熱能大量增加，温度大量提高，而使到PVC制的絕緣层(Insulation
Layer) 燃烧最終導致火患。
短路也是造成火患的其中原因之一，所谓短路是指配线(cable)中的銅制的導电體与另一導电體接触而使到电
阻大幅降低，电流大幅增加而引起的火患。 造成短路的其中两大原因是1）絕緣层被老鼠咬破，2）配线长
期受到日晒雨打，化学物的腐蚀。
根據我國的相關法律有规定每一間新建的建筑物的電路必須由合格的電氣承包商裝備，才能夠獲得入伙紙。
雖然我國有明文規定的法律來防止電路故障所引起的火患，但單單靠法律來防止電路故障所引起的火患是不
夠。我們也應該教育公眾如何防止電路故障所引起的火患。在這方面我相信，國家能源公司，市政局，馬來
西亞工程師協會 消防局應扮演更重要，更積極的角色。
電路故障所引起的意外可造成财物己人命的损失，因此我们立刻采取有效的措施以預防電路故障所引起的意
外。
2009年8月12日 星期三
Philosophy and Politics”
hapter 1 (pages 11-31): “Philosophy and Politics”
http://readingrussell.blogspot.com/search/label/Unpopular%20Essays
Generally, in civilized countries other than modern liberal democracies, the authorities endorse a particular philosophy, as with Soviet Marxism. Early liberal democracies were themselves connected with the philosophy of Locke.
Traditionally philosophy included a doctrine of virtuous behavior. It has been appended to the criminal law and religion to prevent chaos, to make individual desires and the social good cohere. This leads to an insincere philosophy, one that responds not solely to truth but to the fear that “clear thinking would lead to anarchy...[p. 14],” and is exhibited by Plato and Hegel. Protagoras and Hume, skeptics both, are exceptions. It wasn’t the skeptics, but rather the empiricists Democritus and Locke, who were the formidable intellectual opponents with whom Plato and Hegel had to contend. The philosophy of Plato and Hegel “made itself the champion of injustice, cruelty, and opposition to progress [p. 15].” (Russell cites Karl Popper as demonstrating this claim in the case of Plato.) Plato was so artful that people did not recognize “his reactionary tendencies [p. 17]” until Lenin and Hitler put them into practice.
Russell continues by elaborating on the totalitarianism in Plato’s Republic, including the censorship of literature, drama, and music, the sacrifice of individual happiness for the collectivity, and the purposeful deception by the ruling oligarchs to enforce (with the aid of infanticide) their eugenic aspirations. Plato’s ideas require the pretty patina of philosophy to disguise their horrors.
Plato’s purported static optimum is insufficient in a dynamic world, where hope and change are needed for happiness. Modern philosophers thus have adopted an evolutionary viewpoint, where there is progress toward a goal that is never achieved. But change is a scientific notion, and progress is an ethical one. The earth once produced “harmless trilobites and butterflies [p. 19],” but moved on to produce Neros and Hitlers. Peace will return, though, as the earth returns to a state where it cannot support life.
Philosophers are not content with the undirected change of the earth. They note features of the world they like, and others that they don’t like, and then claim that an immutable law of history is leading to an increase in the former and decrease in the latter. “At the same time the winning side, for reasons which remain somewhat obscure, is represented as the side of virtue [p. 20].” Hegel was successful in selling a version of this pap, in part because his writing was so obscure that it was believed to be profound.
Russell provides a capsule and unflattering view of Hegelian philosophy, with its timeless Absolute Idea and the illusory unreality in which we dwell. Hegel somehow is able to conclude from these philosophical foundations that “true liberty consists in obedience to an arbitrary authority, that free speech is an evil, that absolute monarchy is good…[p. 21],” and so on. The intermediate steps involve the logic of the ‘dialectio,’ the uncovering of “contradictions in abstract ideas and correcting them by making them less abstract [p. 22],” with ideas thereby progressing to the Absolute Idea.
Hegel compounds the folly by asserting that “the temporal process of history repeats the logical development of the dialectic [p. 22].” Despite the universality of the philosophy, the historical process applies only to earth, and develops fully only in those times and places on earth with which Hegel was familiar. It was Hegel’s contemporary Germany that has progressed closest to the Absolute Idea.
Hegel’s “farrago of nonsense” carried the day in philosophy for a long time, and Russell would have succumbed, like his peers, had he not seen that Hegel’s writing on the philosophy of mathematics was “plain nonsense [p. 23].” Marx, of course, followed in Hegel’s footsteps, and in much of the world “you will be liquidated if you question this dogma…[p. 23].”
Hegel’s philosophy did not require him to praise Prussia -- his favorable opinion could have been bestowed upon any place with strict governmental control. Hegel (in his own conceit) knew what others did not, and a strong government could force them to act in their own best interest. Russell quotes Heraclitus, “to whom Hegel was deeply indebted,” as noting that ‘Every beast is driven to the pasture with blows.’ Russell’s caustic retort: “Let us, in any case, make sure of the blows; whether they lead to a pasture is a matter of minor importance…[p. 24].”
Once you “know” where history leads, you can justify any sort of compulsion to help people along the path. Autocracy thinks itself justified by some such dogma. Democracy, alternatively, receives a theoretical justification only from Lockean-style empiricism.
A Liberal political theory develops in commercial societies, especially those that are not military powers. Trade brings contacts with foreigners and erodes dogmatism, and successful trading requires an ability to see your partner’s point of view. Liberalism is a "live and let live” approach, one that eschews fanaticism; it accepts no truths, but rather, holds opinions on a tentative basis. Liberalism concerns itself not with what opinions are held, but how they are held. This is the approach of science, though not of theology. “The decisions of the Council of Nicaea are still authoritative, but in science fourth-century opinions no longer carry any weight [p. 26].” Look at how Marxian dogma affects Soviet science. Locke “stood for order without authority…[p. 27].” With the nuclear threat, global survival requires “liberal tentativeness and tolerance [p. 28].”
The realization that your current views may well be wrong suggests that you should be very reluctant to commit a “present evil for the sake of a comparatively doubtful future good [p. 29].”
There is a popular notion that fanatics are likely to win conflicts between themselves and liberals, given the commitment that fanatics have to their cause. But in actual combat, democracies do better. Fanatics choose impossible tasks, or inappropriate means, and “rouse the hostility [p. 30]” of others. Dogmatic systems that seek to persecute others lose out on the contributions – indeed, invite the intense opposition of – the persecuted. Germany might have had the atomic bomb first were it not for Hitler’s hatred of Jews. While fanatic systems can bring social coherence, so can democracies: look at WWII Britain.
Because dogmatism does not accept argument as a way of getting to the truth, all that is left to rival dogmas is force. A robust empirical
http://readingrussell.blogspot.com/search/label/Unpopular%20Essays
Generally, in civilized countries other than modern liberal democracies, the authorities endorse a particular philosophy, as with Soviet Marxism. Early liberal democracies were themselves connected with the philosophy of Locke.
Traditionally philosophy included a doctrine of virtuous behavior. It has been appended to the criminal law and religion to prevent chaos, to make individual desires and the social good cohere. This leads to an insincere philosophy, one that responds not solely to truth but to the fear that “clear thinking would lead to anarchy...[p. 14],” and is exhibited by Plato and Hegel. Protagoras and Hume, skeptics both, are exceptions. It wasn’t the skeptics, but rather the empiricists Democritus and Locke, who were the formidable intellectual opponents with whom Plato and Hegel had to contend. The philosophy of Plato and Hegel “made itself the champion of injustice, cruelty, and opposition to progress [p. 15].” (Russell cites Karl Popper as demonstrating this claim in the case of Plato.) Plato was so artful that people did not recognize “his reactionary tendencies [p. 17]” until Lenin and Hitler put them into practice.
Russell continues by elaborating on the totalitarianism in Plato’s Republic, including the censorship of literature, drama, and music, the sacrifice of individual happiness for the collectivity, and the purposeful deception by the ruling oligarchs to enforce (with the aid of infanticide) their eugenic aspirations. Plato’s ideas require the pretty patina of philosophy to disguise their horrors.
Plato’s purported static optimum is insufficient in a dynamic world, where hope and change are needed for happiness. Modern philosophers thus have adopted an evolutionary viewpoint, where there is progress toward a goal that is never achieved. But change is a scientific notion, and progress is an ethical one. The earth once produced “harmless trilobites and butterflies [p. 19],” but moved on to produce Neros and Hitlers. Peace will return, though, as the earth returns to a state where it cannot support life.
Philosophers are not content with the undirected change of the earth. They note features of the world they like, and others that they don’t like, and then claim that an immutable law of history is leading to an increase in the former and decrease in the latter. “At the same time the winning side, for reasons which remain somewhat obscure, is represented as the side of virtue [p. 20].” Hegel was successful in selling a version of this pap, in part because his writing was so obscure that it was believed to be profound.
Russell provides a capsule and unflattering view of Hegelian philosophy, with its timeless Absolute Idea and the illusory unreality in which we dwell. Hegel somehow is able to conclude from these philosophical foundations that “true liberty consists in obedience to an arbitrary authority, that free speech is an evil, that absolute monarchy is good…[p. 21],” and so on. The intermediate steps involve the logic of the ‘dialectio,’ the uncovering of “contradictions in abstract ideas and correcting them by making them less abstract [p. 22],” with ideas thereby progressing to the Absolute Idea.
Hegel compounds the folly by asserting that “the temporal process of history repeats the logical development of the dialectic [p. 22].” Despite the universality of the philosophy, the historical process applies only to earth, and develops fully only in those times and places on earth with which Hegel was familiar. It was Hegel’s contemporary Germany that has progressed closest to the Absolute Idea.
Hegel’s “farrago of nonsense” carried the day in philosophy for a long time, and Russell would have succumbed, like his peers, had he not seen that Hegel’s writing on the philosophy of mathematics was “plain nonsense [p. 23].” Marx, of course, followed in Hegel’s footsteps, and in much of the world “you will be liquidated if you question this dogma…[p. 23].”
Hegel’s philosophy did not require him to praise Prussia -- his favorable opinion could have been bestowed upon any place with strict governmental control. Hegel (in his own conceit) knew what others did not, and a strong government could force them to act in their own best interest. Russell quotes Heraclitus, “to whom Hegel was deeply indebted,” as noting that ‘Every beast is driven to the pasture with blows.’ Russell’s caustic retort: “Let us, in any case, make sure of the blows; whether they lead to a pasture is a matter of minor importance…[p. 24].”
Once you “know” where history leads, you can justify any sort of compulsion to help people along the path. Autocracy thinks itself justified by some such dogma. Democracy, alternatively, receives a theoretical justification only from Lockean-style empiricism.
A Liberal political theory develops in commercial societies, especially those that are not military powers. Trade brings contacts with foreigners and erodes dogmatism, and successful trading requires an ability to see your partner’s point of view. Liberalism is a "live and let live” approach, one that eschews fanaticism; it accepts no truths, but rather, holds opinions on a tentative basis. Liberalism concerns itself not with what opinions are held, but how they are held. This is the approach of science, though not of theology. “The decisions of the Council of Nicaea are still authoritative, but in science fourth-century opinions no longer carry any weight [p. 26].” Look at how Marxian dogma affects Soviet science. Locke “stood for order without authority…[p. 27].” With the nuclear threat, global survival requires “liberal tentativeness and tolerance [p. 28].”
The realization that your current views may well be wrong suggests that you should be very reluctant to commit a “present evil for the sake of a comparatively doubtful future good [p. 29].”
There is a popular notion that fanatics are likely to win conflicts between themselves and liberals, given the commitment that fanatics have to their cause. But in actual combat, democracies do better. Fanatics choose impossible tasks, or inappropriate means, and “rouse the hostility [p. 30]” of others. Dogmatic systems that seek to persecute others lose out on the contributions – indeed, invite the intense opposition of – the persecuted. Germany might have had the atomic bomb first were it not for Hitler’s hatred of Jews. While fanatic systems can bring social coherence, so can democracies: look at WWII Britain.
Because dogmatism does not accept argument as a way of getting to the truth, all that is left to rival dogmas is force. A robust empirical
2009年7月30日 星期四
Gas metal arc welding
To perform gas metal arc welding, the basic necessary equipment is a welding gun, a wire feed unit, a welding power supply, an electrode wire, and a shielding gas supply.
Most applications of gas metal arc welding use a constant voltage power supply
Alternating current is rarely used with GMAW; instead, direct current is employed and the electrode is generally positively charged(DCEP)
Electrode
The selection of electrode depends on the process variation being used, the composition of the metal being welded, the joint design, and the material surface conditions.
All electrode contain deoxidizing metals such as silicon, manganese, titanium, and aluminum in small percentages to help prevent oxygen porosity, and some contain denitriding metals such as titanium and zirconium to avoid nitrogen porosity.[9]
The diameters of the electrodes used in GMAW typically range from 0.7 to 2.4 mm (0.028–0.095 in), but can be as large as 4 mm (0.16 in). The smallest electrodes are associated with short-circuiting metal transfer, while the pulsed spray mode generally uses electrodes of at least 1.6 mm (0.06 in).[10]
Shielding gas
Shielding gases are necessary for gas metal arc welding to protect the welding area from atmospheric gases such as nitrogen and oxygen, which can cause fusion defects, porosity, and weld metal embrittlement if they come in contact with the electrode, the arc, or the welding metal. This problem is common to all arc welding processes, but instead of a shielding gas, many arc welding methods utilize a flux material which disintegrates into a protective gas when heated to welding temperatures. In GMAW, however, the electrode wire does not have a flux coating, and a separate shielding gas is employed to protect the weld. This eliminates slag, the hard residue from the flux that builds up after welding and must be chipped off to reveal the completed weld.
The choice of a shielding gas depends on several factors, most importantly the type of material being welded and the process variation being used. Pure inert gases such as argon and helium are only used for nonferrous welding; with steel they cause an erratic arc and encourage spatter (with helium) or do not provide adequate weld penetration (argon). Pure carbon dioxide, on the other hand, allows for deep penetration welds but encourages oxide formation, which adversely affect the mechanical properties of the weld. Its low cost makes it an attractive choice, but because of the violence of the arc, spatter is unavoidable and welding thin materials is difficult. As a result, argon and carbon dioxide are frequently mixed in a 75%/25% or 80%/20% mixture, which reduces spatter and makes it possible to weld thin steel workpieces.
Argon is also commonly mixed with other gases, such as oxygen, helium, hydrogen, and nitrogen. The addition of up to 5% oxygen encourages spray transfer, which is critical for spray-arc and pulsed spray-arc GMAW. However, more oxygen makes the shielding gas oxidize the electrode, which can lead to porosity in the deposit if the electrode does not contain sufficient deoxidizers. An argon-helium mixture is completely inert, and is used on nonferrous materials. A helium concentration of 50%–75% raises the voltage and increases the heat in the arc, making it helpful for welding thicker workpieces. Higher percentages of helium also improve the weld quality and speed of using alternating current for the welding of aluminum. Hydrogen is added to argon in small concentrations (up to about 5%) for welding nickel and thick stainless steel workpieces. In higher concentrations (up to 25% hydrogen), it is useful for welding conductive materials such as copper. However, it should not be used on steel, aluminum or magnesium because of the risk of hydrogen porosity. Additionally, nitrogen is sometimes added to argon to a concentration of 25%–50% for welding copper, but the use of nitrogen, especially in North America, is limited. Mixtures of carbon dioxide and oxygen are similarly rarely used in North America, but are more common in Europe and Japan.
Recent advances in shielding gas mixtures use three or more gases to gain improved weld quality. A mixture of 70% argon, 28% carbon dioxide and 2% oxygen is gaining in popularity for welding steels, while other mixtures add a small amount of helium to the argon-oxygen combination, resulting in higher arc voltage and welding speed. Helium is also sometimes used as the base gas, to which smaller amounts of argon and carbon dioxide are added. Additionally, other specialized and often proprietary gas mixtures claim to offer even greater benefits for specific applications.[11]
The desirable rate of gas flow depends primarily on weld geometry, speed, current, the type of gas, and the metal transfer mode being utilized. Welding flat surfaces requires higher flow than welding grooved materials, since the gas is dispersed more quickly. Faster welding speeds mean that more gas must be supplied to provide adequate coverage. Additionally, higher current requires greater flow, and generally, more helium is required to provide adequate coverage than argon. Perhaps most importantly, the four primary variations of GMAW have differing shielding gas flow requirements—for the small weld pools of the short circuiting and pulsed spray modes, about 10 L/min (20 ft³/h) is generally suitable, while for globular transfer, around 15 L/min (30 ft³/h) is preferred. The spray transfer variation normally requires more because of its higher heat input and thus larger weld pool; along the lines of 20–25 L/min (40–50 ft³/h).[12]
The orientation of the gun is also important—it should be held so as to bisect the angle between the work pieces; that is, at 45 degrees for a fillet weld and 90 degrees for welding a flat surface. The travel angle or lead angle is the angle of the torch with respect to the direction of travel, and it should generally remain approximately vertical. However, the desirable angle changes somewhat depending on the type of shielding gas used—with pure inert gases, the bottom of the torch is out often slightly in front of the upper section, while the opposite is true when the welding atmosphere is carbon dioxide.[14
SAFETY HAZARD S INCLUDE
Extreme heat and flame
Ultraviolet light
Particulate matter
Carbon monoxide
Ozone
GLOBULAR TRANSFER
As the weld is made, a ball of molten metal from the electrode tends to build up on the end of the electrode, often in irregular shapes with a larger diameter than the electrode itself. When the droplet finally detaches either by gravity or short circuiting, it falls to the workpiece, leaving an uneven surface and often causing spatter.
limited to flat and horizontal welding positions
tendency to produce high heat, a poor weld surface, and spatter.
uses carbon dioxide,
high deposition rate,
SHORT CIRCUIT TRANSFER
Molten droplets form on the tip of the electrode, but instead of dropping to the weld pool, they bridge the gap between the electrode and the weld pool as a result of the greater wire feed rate. This causes a short circuit and extinguishes the arc, but it is quickly reignited after the surface tension of the weld pool pulls the molten metal bead off the electrode tip.
This process is repeated about 100 times per second, making the arc appear constant to the human eye.
possible to weld thinner materials
better weld quality and less spatter than the globular variation, and it allows for welding in all positions but slower
SPRA Y TRANSFER :
Molten metal droplets (with diameters smaller than the electrode diameter) are rapidly passed along the stable electric arc from the electrode to the work piece
eliminating spatter and resulting in a high-quality weld finish.
high amounts of voltage and current are necessary
used only on workpieces of thicknesses above about 6 mm (0.25 in).
it is often limited to flat and horizontal welding position
The maximum deposition rate for spray arc GMAW is relatively high; about 60 mm/s (150 in/min).[22
PULSE TRANSFER
Based on the principles of spray transfer but uses a pulsing current to melt the filler wire and allow one small molten droplet to fall with each pulse.
The pulses allow the average current to be lower, decreasing the overall heat input and thereby decreasing the size of the weld pool and heat-affected zone while making it possible to weld thin work pieces
The smaller weld pool gives the variation greater versatility, making it possible to weld in all positions.
it requires a special power source capable of providing current pulses with a frequency between 30 and 400 pulses per second.
Most applications of gas metal arc welding use a constant voltage power supply
Alternating current is rarely used with GMAW; instead, direct current is employed and the electrode is generally positively charged(DCEP)
Electrode
The selection of electrode depends on the process variation being used, the composition of the metal being welded, the joint design, and the material surface conditions.
All electrode contain deoxidizing metals such as silicon, manganese, titanium, and aluminum in small percentages to help prevent oxygen porosity, and some contain denitriding metals such as titanium and zirconium to avoid nitrogen porosity.[9]
The diameters of the electrodes used in GMAW typically range from 0.7 to 2.4 mm (0.028–0.095 in), but can be as large as 4 mm (0.16 in). The smallest electrodes are associated with short-circuiting metal transfer, while the pulsed spray mode generally uses electrodes of at least 1.6 mm (0.06 in).[10]
Shielding gas
Shielding gases are necessary for gas metal arc welding to protect the welding area from atmospheric gases such as nitrogen and oxygen, which can cause fusion defects, porosity, and weld metal embrittlement if they come in contact with the electrode, the arc, or the welding metal. This problem is common to all arc welding processes, but instead of a shielding gas, many arc welding methods utilize a flux material which disintegrates into a protective gas when heated to welding temperatures. In GMAW, however, the electrode wire does not have a flux coating, and a separate shielding gas is employed to protect the weld. This eliminates slag, the hard residue from the flux that builds up after welding and must be chipped off to reveal the completed weld.
The choice of a shielding gas depends on several factors, most importantly the type of material being welded and the process variation being used. Pure inert gases such as argon and helium are only used for nonferrous welding; with steel they cause an erratic arc and encourage spatter (with helium) or do not provide adequate weld penetration (argon). Pure carbon dioxide, on the other hand, allows for deep penetration welds but encourages oxide formation, which adversely affect the mechanical properties of the weld. Its low cost makes it an attractive choice, but because of the violence of the arc, spatter is unavoidable and welding thin materials is difficult. As a result, argon and carbon dioxide are frequently mixed in a 75%/25% or 80%/20% mixture, which reduces spatter and makes it possible to weld thin steel workpieces.
Argon is also commonly mixed with other gases, such as oxygen, helium, hydrogen, and nitrogen. The addition of up to 5% oxygen encourages spray transfer, which is critical for spray-arc and pulsed spray-arc GMAW. However, more oxygen makes the shielding gas oxidize the electrode, which can lead to porosity in the deposit if the electrode does not contain sufficient deoxidizers. An argon-helium mixture is completely inert, and is used on nonferrous materials. A helium concentration of 50%–75% raises the voltage and increases the heat in the arc, making it helpful for welding thicker workpieces. Higher percentages of helium also improve the weld quality and speed of using alternating current for the welding of aluminum. Hydrogen is added to argon in small concentrations (up to about 5%) for welding nickel and thick stainless steel workpieces. In higher concentrations (up to 25% hydrogen), it is useful for welding conductive materials such as copper. However, it should not be used on steel, aluminum or magnesium because of the risk of hydrogen porosity. Additionally, nitrogen is sometimes added to argon to a concentration of 25%–50% for welding copper, but the use of nitrogen, especially in North America, is limited. Mixtures of carbon dioxide and oxygen are similarly rarely used in North America, but are more common in Europe and Japan.
Recent advances in shielding gas mixtures use three or more gases to gain improved weld quality. A mixture of 70% argon, 28% carbon dioxide and 2% oxygen is gaining in popularity for welding steels, while other mixtures add a small amount of helium to the argon-oxygen combination, resulting in higher arc voltage and welding speed. Helium is also sometimes used as the base gas, to which smaller amounts of argon and carbon dioxide are added. Additionally, other specialized and often proprietary gas mixtures claim to offer even greater benefits for specific applications.[11]
The desirable rate of gas flow depends primarily on weld geometry, speed, current, the type of gas, and the metal transfer mode being utilized. Welding flat surfaces requires higher flow than welding grooved materials, since the gas is dispersed more quickly. Faster welding speeds mean that more gas must be supplied to provide adequate coverage. Additionally, higher current requires greater flow, and generally, more helium is required to provide adequate coverage than argon. Perhaps most importantly, the four primary variations of GMAW have differing shielding gas flow requirements—for the small weld pools of the short circuiting and pulsed spray modes, about 10 L/min (20 ft³/h) is generally suitable, while for globular transfer, around 15 L/min (30 ft³/h) is preferred. The spray transfer variation normally requires more because of its higher heat input and thus larger weld pool; along the lines of 20–25 L/min (40–50 ft³/h).[12]
The orientation of the gun is also important—it should be held so as to bisect the angle between the work pieces; that is, at 45 degrees for a fillet weld and 90 degrees for welding a flat surface. The travel angle or lead angle is the angle of the torch with respect to the direction of travel, and it should generally remain approximately vertical. However, the desirable angle changes somewhat depending on the type of shielding gas used—with pure inert gases, the bottom of the torch is out often slightly in front of the upper section, while the opposite is true when the welding atmosphere is carbon dioxide.[14
SAFETY HAZARD S INCLUDE
Extreme heat and flame
Ultraviolet light
Particulate matter
Carbon monoxide
Ozone
GLOBULAR TRANSFER
As the weld is made, a ball of molten metal from the electrode tends to build up on the end of the electrode, often in irregular shapes with a larger diameter than the electrode itself. When the droplet finally detaches either by gravity or short circuiting, it falls to the workpiece, leaving an uneven surface and often causing spatter.
limited to flat and horizontal welding positions
tendency to produce high heat, a poor weld surface, and spatter.
uses carbon dioxide,
high deposition rate,
SHORT CIRCUIT TRANSFER
Molten droplets form on the tip of the electrode, but instead of dropping to the weld pool, they bridge the gap between the electrode and the weld pool as a result of the greater wire feed rate. This causes a short circuit and extinguishes the arc, but it is quickly reignited after the surface tension of the weld pool pulls the molten metal bead off the electrode tip.
This process is repeated about 100 times per second, making the arc appear constant to the human eye.
possible to weld thinner materials
better weld quality and less spatter than the globular variation, and it allows for welding in all positions but slower
SPRA Y TRANSFER :
Molten metal droplets (with diameters smaller than the electrode diameter) are rapidly passed along the stable electric arc from the electrode to the work piece
eliminating spatter and resulting in a high-quality weld finish.
high amounts of voltage and current are necessary
used only on workpieces of thicknesses above about 6 mm (0.25 in).
it is often limited to flat and horizontal welding position
The maximum deposition rate for spray arc GMAW is relatively high; about 60 mm/s (150 in/min).[22
PULSE TRANSFER
Based on the principles of spray transfer but uses a pulsing current to melt the filler wire and allow one small molten droplet to fall with each pulse.
The pulses allow the average current to be lower, decreasing the overall heat input and thereby decreasing the size of the weld pool and heat-affected zone while making it possible to weld thin work pieces
The smaller weld pool gives the variation greater versatility, making it possible to weld in all positions.
it requires a special power source capable of providing current pulses with a frequency between 30 and 400 pulses per second.
Turned Process
Turned part include :i) Bolt ,ii) Shafts ,iii) Spindle ,iv) Washer.
Three motion involved in Lathe turning are
The rotating motion of the work piece is called ‘Cutting or main motion’. The speed at which the material is removed from work piece by the cutting edge is called ‘cutting speed’
The cutting tool moves forward at a uniform rate forming a continuous chip (Feed motion)
The turning tool is set to desire depth of cut( Adjusting motion)
STRAIGHT TURNING -The work pieces are given cylindrical shape by straight turning , in which cutting tool move parallel to the axis of the turning spindle.
FACING The work pieces are given plane surface by facing , in which cutting tool move perpendicular to the axis of the turning spindle.
TAPER TURNING:The work pieces are given taper shape by taper turning operation , in which cutting tool move at angle to the axis of the turning spindle.
Center lathe , engine lathe and longitudinal turning lathes are used interchangeably
HEAD STOCK In the head stock (Picture) the main spindle on the bearings transmit the rotary motion to the work piece.
In most cases spindles are hollow so as to guide the bar stock through
Bearing :plain bearing , thrust bearing , ball and roller bearing
Head of spindle is provided with a thread to fix chuck and also provided with tapered hole to accommodate centers
Spindle is driven by motor through gear train
CARRIAGE :Supports and carries cutting tool
Contains feed mechanism and its adjustment
Consists of saddle , cross slide , compound slide , tool holder and apron.
The saddle and the cross slide are either operated by feed shaft or the leadscrew
TAILSTOCK:Serves as a support for turning long work piece
Provided with MORSE taper to accommodate
center , twist drill, boring tool ,reamer
Tail stock can be offset for taper turning
BED :Carries all lathe parts
The carriage and tailstock move on the guide way which are usually V and flat shaped.
Turning tool can be made of unalloyed tool steel, alloy tool steel, cemented carbide and diamond tip
Shank serves the purpose of clamping
Tool point consists of cutting edges
Cut face is the surface on the work piece which is formed by the cutting edge of the tool
The machined surface is the surface of the work piece obtained by the cutting process
The top face is the surface on which the chip curls .
The clearance face is the surface of the tool point, directed against the cut face.
The clearance angle is the angle between top face and clearance face
The rake angle is the angle between normal of the cut face and the top face
Clearance ,wedge and rake angle add up to 90 degree
The primary cutting edge is the cutting edge on the feed side
The secondary cutting edge is the cutting edge subsequent to the primary cutting edge
The Plan angle is situated between the primary cutting edge and machine surface. When turning with large plan angle the thickness of the chip is small , the cutting pressure is ditributed on a short portion of the cutting edge , tool life shortened and vice versa.
The nose angle is enclosed between primary cutting edge and secondary cutting edge tool with small nose angle blunt quickly.
The inclination angle determine the position of the primary cutting edge towards the horizontal line
Type of cutting tool include roughing tool , finishing tool and side tools
Toolpost include ordinary tool post and four way tool post.
Cutting tools should be set at center to obtain optimun results .
Cutting Speed =22/7 *RPM *D cirmeferential length of chip cut in one minute , depends on 1) Work piece material,2) Cutting tool materials,3) Cross section of the chip , 4)Cooling ,5) Machine Design
Feed means longitidunal distance travel for one full turning of work piece
Depth of cut means amount of penetration into the work piece to obtain a desired size.
A Typical operation plan sequence for manufacturing of bolt are
1) Chucking
2)Roughing and finishing of 1st step
3)Turning to length and deburing of 1st step
4)Rechucking
5)Roughing , finishing , turning to length and deburring of 2nd step
Three motion involved in Lathe turning are
The rotating motion of the work piece is called ‘Cutting or main motion’. The speed at which the material is removed from work piece by the cutting edge is called ‘cutting speed’
The cutting tool moves forward at a uniform rate forming a continuous chip (Feed motion)
The turning tool is set to desire depth of cut( Adjusting motion)
STRAIGHT TURNING -The work pieces are given cylindrical shape by straight turning , in which cutting tool move parallel to the axis of the turning spindle.
FACING The work pieces are given plane surface by facing , in which cutting tool move perpendicular to the axis of the turning spindle.
TAPER TURNING:The work pieces are given taper shape by taper turning operation , in which cutting tool move at angle to the axis of the turning spindle.
Center lathe , engine lathe and longitudinal turning lathes are used interchangeably
HEAD STOCK In the head stock (Picture) the main spindle on the bearings transmit the rotary motion to the work piece.
In most cases spindles are hollow so as to guide the bar stock through
Bearing :plain bearing , thrust bearing , ball and roller bearing
Head of spindle is provided with a thread to fix chuck and also provided with tapered hole to accommodate centers
Spindle is driven by motor through gear train
CARRIAGE :Supports and carries cutting tool
Contains feed mechanism and its adjustment
Consists of saddle , cross slide , compound slide , tool holder and apron.
The saddle and the cross slide are either operated by feed shaft or the leadscrew
TAILSTOCK:Serves as a support for turning long work piece
Provided with MORSE taper to accommodate
center , twist drill, boring tool ,reamer
Tail stock can be offset for taper turning
BED :Carries all lathe parts
The carriage and tailstock move on the guide way which are usually V and flat shaped.
Turning tool can be made of unalloyed tool steel, alloy tool steel, cemented carbide and diamond tip
Shank serves the purpose of clamping
Tool point consists of cutting edges
Cut face is the surface on the work piece which is formed by the cutting edge of the tool
The machined surface is the surface of the work piece obtained by the cutting process
The top face is the surface on which the chip curls .
The clearance face is the surface of the tool point, directed against the cut face.
The clearance angle is the angle between top face and clearance face
The rake angle is the angle between normal of the cut face and the top face
Clearance ,wedge and rake angle add up to 90 degree
The primary cutting edge is the cutting edge on the feed side
The secondary cutting edge is the cutting edge subsequent to the primary cutting edge
The Plan angle is situated between the primary cutting edge and machine surface. When turning with large plan angle the thickness of the chip is small , the cutting pressure is ditributed on a short portion of the cutting edge , tool life shortened and vice versa.
The nose angle is enclosed between primary cutting edge and secondary cutting edge tool with small nose angle blunt quickly.
The inclination angle determine the position of the primary cutting edge towards the horizontal line
Type of cutting tool include roughing tool , finishing tool and side tools
Toolpost include ordinary tool post and four way tool post.
Cutting tools should be set at center to obtain optimun results .
Cutting Speed =22/7 *RPM *D cirmeferential length of chip cut in one minute , depends on 1) Work piece material,2) Cutting tool materials,3) Cross section of the chip , 4)Cooling ,5) Machine Design
Feed means longitidunal distance travel for one full turning of work piece
Depth of cut means amount of penetration into the work piece to obtain a desired size.
A Typical operation plan sequence for manufacturing of bolt are
1) Chucking
2)Roughing and finishing of 1st step
3)Turning to length and deburing of 1st step
4)Rechucking
5)Roughing , finishing , turning to length and deburring of 2nd step
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