液压机的设计外文文献翻译

附录A

液压机

水由高处下降到一个低的高度的时候能产生能量, 可以用来驱动水轮和涡轮等机械.最高和最低水位之间的落差决定了每磅水的能量。水力可以来自很多自然资源, 例如瀑布和建有大坝的河流等.在没有自然资源的情况下, 可以修建人工水库。当能量充足的时候可以抽水到水库来储存水能, 当能量不足的时候, 这些储存起来的水可提供能量来驱动涡轮。

工业的液压机械的某些称作储蓄器的机械装置被用来短时间的提供高效的功率.活塞负载重量后装入缸体中, 然后水被缓慢的压入缸体, 活塞和活塞负载的重物给强迫的升到一个高的位置, 当放下他们是,他们强迫缸体中的水迅速的流出, 为机器提供水的压力能。

液压机是由一种液体,特别是水的压力来操纵。他们在工程领域的广泛应用,例如: 地层移动、矿业、建筑机械、汽车工程、纺织工业、电站、农业机械等。液压设备

水、油压力是常用的动力源, 比如压力机、铆机、起锚机、绞盘等机械. 水压或者静水力压是约瑟夫布拉玛(Joseph Bramah)发现的, 因此优势也称布拉玛压力. 他主要包括连个缸体, 一个是用液体填充, 一个用活塞. 两个缸体用管子连接起来, 也同样用液体填充。一个缸体是小直径的, 另一个是大直径的. 根据帕斯卡定律, 外界作用在小活塞上压强通过液体毫无损失的传到被迫上升的大活塞的表面。对于两个活塞来说, 压强(单位面积压力)是相同, 作用在大活塞上向上的压力是作用在小活塞的几倍, 因为大活塞的面积是小活塞的几倍. 比如, 举个例子, 小活塞的面积是2平方英寸, 100lb的压力作用在它上面, 于是作用在具有50平方英寸面积的大活塞上的压力就会有25000lb(100×50/2=2,500). 然而, 让活塞一定时, 小活塞一定的距离也成比例的大于大活塞移动的距离, 这满足能量转换定律。如果小活塞移动25 英寸,大的活塞就会只移动1英寸。水压被使用了, 比如, 使三维的物体从一片金属压缩成一个大的物体。

压力起重器, 同样是帕斯卡定律的一项应用, 用来施加大的压力或者提升

重物。

液压机,也是实施帕斯卡尔的定律,是用来产生大力量和负重。像水压机,它是由两个不同尺寸的活塞筒中,由管道相连。当小活塞来回移到了相关处理,但液体泵入较大的圆筒活塞,迫使大型活塞议案。这样力量薄弱的小型活塞可以应用于提高了一大沉重负担。液压电梯也是适用Pascal的定律。象水压一样, 它的汽缸中包括两个用管子连接起来的不同大小的活塞, 当小些的活塞靠连在他上面的手柄来回移动的时候, 压迫液体进入大活塞的汽缸, 强制大活塞移动。这样, 小力气可以使用小活塞升起很重的负载。压力电梯同样是帕斯卡定律的一项应用。

水压机

水压机是一种机械设备, 大的外界力量施加在一对缸体中的大活塞的上, 这就是说相应的小的力量被施加到小的活塞上。通过这中创新的想法他们能展现更好的性能——液压压力由5000吨增至5吨。

操纵模式：

¤水压机有特定的操纵模式；

¤ 全自动“PLC”-控制；

¤ 基于继电器控制。

框架结构：

水压机的框架结构是:

¤ “H”型或者4列型

¤ “C”型

¤ 4-柱型 (硬铝合金柱型)

应用

水压机有下面几种应用:

1. 深度汲取作业

2. 打孔

3. 铆接、冲压

4. 强力压迫

5. 其他应用,例如: FRP, SMC, DMC、橡胶塑料等.

压力机的特征:

1.这些压力机提供快捷的方式缓慢的积压&快速的返回. 变化速度可以人工进行预定；

2.该结构经过超声波质量测试，能承受长时间的负载和重压；

3.通过计算机半自动的结构设计和有限元分析达到了极大化结构刚度；

4.额外的长期的，精确的操纵进一步缩小磨损的额外精度设计；

5.关闭或一拳打在液压阻尼系统可以安装压力. 这将有效突破,通常产生噪音的科学手段穿上这种行动；

6.低噪音包水电设计单位按国际惯例,国际知名的科学组装部件作. 按统计学的印刷设计准则,因而标准印章、灌木使用；

7. "逻辑控制器"(PLC)是在符合国际标准的压力也使ABB/艾伦-布拉德利/西门子/Telemacqnice/Keyance提供最大的灵活性和收购生产完全符合国际标准；8.精确的机械结构都是正常化后得到的所需的准确度及与PLATEN科学之间的角度提出的PLATEN；

9.润滑油: 方式/可以从油孔中心注油；

10.移动PLATEN:这是假想的、重型的、工程测试板焊接性能最高的负荷重量. PLATEN全是压力减轻后焊接. 按platen标准规定't'时间. 液压系统或机械操作按内部RAM要求也提供选择性的请求或申请.

11.卡死或铁轨滑动的安排方式也提供了支持选择性信息的一种重要应用工具.类型:

C 框架类型受力:

1.这些对所在区域的压力提供最大输入量，目的是为改变工具及组成成分的供

给。

2.范围: 5吨到300 吨容量。

3.间断式可能是双柱类型或单体类型结构。

4.液压动力机组内部所有阀门是多头管型的，目的是为了容易快速的维护和压

力减轻阀门保护免受超载影响。

5.附加设备: a. 喷射器在。b. 模子缓冲装置。

6. 坚硬镀铬型立柱类型:这些机构指导提供移动的部件的准确性。并增加部件的

可靠性。部件移动在更大的铜/钢轴承上，并在各个位置以适当的润滑，从而为整个机构的正常运行提供良好的环境。

流体静力的压力的原则

液体的施力方向是面向四面八方。所以这种力的应用方式足够简单。那么压力能够有多么大呢? 这里进行尝试一个小的实验。在您的桌子前面安置一堆物块。把您的手指要求放在从上边数第一块的下面。对你的手指有一定压力是吗? 把它在三之间和四块。压力在您的手指增加了。现在把您的手指放在所有物块的最最下端，您将发现那里的压力是最大的，也就是说压力随着你手指下移而增大。您也许说, 压力增加随深度增加。同样是在液体里，把手指深深的放进去，压力将变得非常巨大，但是, 深度不是原因。

假设放在前面的物块由多角制成，压力在堆里任一个方向上会是可观地加大的。或假设他们是的沿着水平方向块压力在各个水平方向不是增大的。则可以断定, 压力取决于不仅是深度, 而且是材料的重量。因为您应付压力力量单位体积内, 您并且负担没单位体积内物体的重量和密度。当您谈论物质的密度, 您谈论它的重量每立方英尺或每立方英寸。例如, 密度水是62.5 磅每立方英尺; 密度主角是710 磅每立方英尺。但是, 比水更重的却不是正常的现象。例如, 22 口径子弹和一个桶水是密度一样, 但桶水是更重的。它是真实的, 然而, 一立方英尺铁比一立方英尺的水重。

压力取决于二原则：深度和密度。您能容易地发现压力在任一深度在任一液体由使用以下惯例:

=?

P H D

式中：

P 为压力，Pa； H 为该点的深度, m。

注: 如果在您的计算中使用英寸, 您必须始终使用他们; 如果您使用米, 您也必须始终使用他们。

什么是在潜水艇的表面的1 平方米产生的压力？如果潜水艇是200 英尺在表面之下? 使用惯例:

=?

P H D

P= 200 x 62.5 = 12,500Pa

是在那深度的潜水艇的表面的每平方英尺有超过6 吨力量排挤应力。如果船身的高度是20 英尺并且区域在考虑中是在潜水艇的上面和底部之间, 您能看, 压力在船身将是至少(200 - 10) x 62.5 = 11,875 N每平方英尺。最巨大的压力将是(200 + 10) x 62.5 = 13,125 N每平方英尺。明显地, 船身必须是非常坚固的才能承受这样压力。

液压缸

液压缸是被用来加压的液压元件，它是依靠液体使元件产生线性运动和应力的驱动设备。液压缸被使用在各种各样的力的应用中。经营的规格、配置或架置、建筑材料, 和特点是选择液压缸首要的考虑因素。

液压缸的重要规格包括圆筒类型、冲程、最大工作压力、打扰直径, 和标尺直径。

选择为圆筒类型包括连接杆,焊接和填塞。使用一个或更多连接杆提供另外的稳定的连接杆是圆筒液压缸。连接杆通常典型地被安装在圆筒型的外部直径处。在许多应用中, 圆筒连接杆承受多数的应用的装载次数。使用一套耐用被焊接的圆筒可提供稳定的应用数据。液压缸是一个被焊接的光滑的圆筒。填塞圆筒是作为填塞类型的液压缸。一个液压油缸的里活塞标尺断面是超过二分之一的部分，是可移动的断面的设备。液压油缸主要被使用推挤而不是拉扯, 而且通常是在高压环境中应用。冲程是活塞在缸筒中运动的最大距离。液压缸可能有各种各样的冲程长度, 从一英寸的分数到许多英尺。最大工作压力是圆筒可能承受的最大工作压力。缸筒直径缸筒内圆的直径。标尺直径是被使用在圆筒的标尺或活塞的直径。选择为圆筒配置是简单的配置或望远镜形。一种简单的结构液压缸包括唯一圆柱形缸筒和内部元件。一种望远镜配置液压缸使用"挤撞" 圆柱形缸筒来扩大圆筒的长度。望远镜配置圆筒被使用在要求对一个长的圆筒的用途在一个空间特殊的环境里的不同应用。液压缸可能是单一行程或双重行程。一次唯一运动液压缸只在一个方向上施加压力。一次双重行动液压缸可能行动沿水平(Ｘ轴) 面, 垂直的(Ｙ轴) 飞运动沿其他方向运动。选择架构的方法包括耳轮缘、耳轴, 穿线, U-形钩或目测。登上地点可能是缸盖、两端或中间体。生产材料包括钢、不锈钢和铝。共同的特点为液压缸包括缺一不可的传感器、双重末端标尺、液压

缸数据表和可调整的冲程。

液压缸是使用在使被施加压力液体的液压机产生线性行动和动力的驱动设备。液压缸被使用在各种各样的动力应用。

区别在气缸和液压缸之间是他们供给动力的方式。当空气圆筒引起线性行动和力量通过气动力学的力量, 液压缸用途加压了流体。液压缸是可利用的在三主要型(微型液压缸也可使用): 连接杆, 被焊接和填塞。

连接杆液压缸使用一个或更多连接杆增加稳定性。连接杆典型地被安装在圆筒的外部。在许多应用, 连接杆在这些精确度液压缸里负担应用的装载的多数。被焊接的圆筒提供光滑的运动，由于他们的使用被焊接的圆筒, 提供稳定性。液压油缸有活塞标尺的一个断面, 是超过二分之一移动的组分的断面。液压油缸主要被使用推挤而不是拉扯, 而且是最常用在高压应用。

除他们的类型之外, 液压缸可能被根据了他们的配置区分。二种主要配置是简单和望远镜的(习惯液压缸配置再是可利用的) 。简单的配置液压缸包括唯一圆柱形住房和内部元件。这是基本的液压缸设计由多数液压缸制造商使用。望远镜液压缸使用"挤撞" 圆柱形住房扩大圆筒的长度。挤撞液压缸被使用在要求对一个长的圆筒的用途在一个空间拘束的环境里的各种各样的应用。

根据行动, 液压缸可能是唯一行动或双重行动设计。唯一行动圆筒被加压为行动在只一个方向。频繁地被使用带来圆筒活塞回到原始位置。双重行动液压缸可能行动沿水平(Ｘ轴) 面, 垂直的(Ｙ轴) 方向或沿其他方向运动。圆筒活塞的双方可能被加压为反复性行动。力量规定值可能不同，有些在相反方向。

一般液压机构的组成

电源单位提供必要的液体压力- 从主驱动电动机转换机械动力。

1.电源部分:

最重要的组成部分在动力源是泵。这画在液压机液体油箱旁边，并且由它通过线性系统在液体压力下抵抗负载力。压力不加强直到流动的液体遇到负载。油液过滤单位经常也包含在电源部分。杂质可能进入系统由于是热或冷的机械磨损、油, 或外在环境影响。因此, 过滤器被安装在水力电路从液压机液体去除土微粒。水和气体在油是还破裂物质并且必须采取特别措施防止他们的产生。加热器和致冷机被安装来调节液压机液体。这对液压机实际应用中的需要有着特殊的

作用。

油箱的作用在于储存液压机需要的工作液体:

-- 过滤和气体分离由相应的部件；

-- 通过他们的表面是使液体冷却。

2.液压部分

流体这是转移准备的能量电源单位到驱动部分的工作媒介(圆筒或马达) 。液压机液体有各种各样的特征。所以, 他们必须被选择适合应用在考虑中。按不同情况进行调整，液压机液体在一个矿物油基地频繁地被使用; 这些指压力油。

3.阀门

阀门是设备为控制能量流程。他们能控制和调控液压机液体、压力、流速和, 因而, 流程速度的流程方向。

有四种阀门类型被选择与问题符合在考虑中。直通控制阀这些阀门控制流程液压机液体和, 因而, 方向行动和安置的方向运作的组分。定向控制阀用手工, 机械上, 电子, 气动力学来控制开动或液压.他们改变位置和放大信号(手工, 电或气动力学) 形成一个接口在电能控制部分和信号控制段之间。

1.压力阀工作在一种完全液压机构或在系统的部份，他们能够影响工作压力。操作方法这些阀门的根据事实有效的压力从系统行动在表面在阀门。总值量与负载平衡。

2.流程控制阀门这交互式与压力阀影响流速。他们使成为可能控制或调控运动速度力量组分的。那里流速是恒定的, 流程变化必须发生。这一般被影响通过流程控制阀门的互作用与压力阀。

3.单向阀门在这类型阀门情况下, 分别被做在普通的单向阀门和被控制的单向阀门之间。在被控制的单向阀门情况下, 流程在封锁的方向可能由信息控制。圆筒是转换水力成机械动力的驱动组分。他们引起线性运动通过压力在可移动的活塞的表面。

4.缸筒(线性执行机构)单作用圆筒可变的压力只能向活塞的一边作用，驱动运动只导致在活塞的一个方向.回归冲程在一个弹簧的外力作用下产生。例子: Hydraulic ；Telescopic。驾驶运动被生产在二个方向的双作用圆筒可变的压力可能向或者活塞意思的一边被应用。例子: Telescopic 有差别的圆

Synchronous。

正如液压缸一样, 水力马达是驱动组分由阀门控制。他们太转换水力成机械动力以区别, 他们引起转台式或转体运动代替线性运动。

灵活的液压机构

工程师在Teruel 附近修建新环行公路在西班牙与专家Enerpac 可能适应为上升和下坡行驶的所有四座桥梁及机动车路，总共16,6 公里长，新公路在巴伦西亚和Zaragoza之间的一个灵活的液体压力系统。

新旁路将构成巴伦西亚的部分对当前被修造的Zaragoza 机动车路。很大程度上, 这条高速公路的建筑包括升级现有的单向公路到机动车路标准, 但在Teruel, 改路通过城市的中心。

作为个体构造旁路的形式零件被修造围绕Teruel 在西班牙东北部分,似乎是可能的方案有增加发射的四座新桥梁。他们对公路的标称是：最长是325m。既使他们两个被形成对称的结构, 一个为各条车道。虽然他们相似, 他们不是相同的- 主要区别是倾斜、十字架秋天和计划曲度。但即使如此, 承包商Dragados 决定修造他们使用增加发射, 和工作与Enerpac, 专家在水力集成系统使土木工程开发可能适应至于使用在所有四个结构的一个简单和灵活的系统。如同Drace (Dragados Construccione Especiales) 发射的经理Carlos Polimon 解释, 地形在Teruel 附近是有些多小山的, 提示需要为许多结构- 有总共五座桥梁。

四座被建造的桥梁, 各自对应结构因此那里是八个舱板建造总共- 被设计一样相似象可能使发射的设备从一个被移动向其他以极小的可能。他们全都有同样横断面, 并且距离码头在52m 之间, 是恒定的为各个结构。但有并且区别。当Polimon 指出, 他们不也许似乎乍一看非常大区别, 但是当它来到计划铸件和建造时, 他们证明相当重要。桥梁第号你是平直的在计划, 以一个纵向倾斜4% 和一个发怒秋天的2% 从里面边缘对外部边缘在各个舱板。桥梁第二弯曲在计划以半径3200 米, 当三和四每曲线以半径5000 米。在这些三座桥梁, 纵向倾斜是相同的在1,3%, 但但是二他们将被发射反对倾斜, 三将是排出的液体。变化率是2,7%, 在两个舱板下落朝曲线的中间, 和相似地在三和四, 虽然这里发怒秋天被减少到2% 。

如此系统由可能被使用在所有四个结构的Drace 和专家供应商Enerpac 开发了, 并且整个“工厂” - 铸件围场和发射的设备- 从一个站点将被调迁对下在各个结构的完成以后。二套设备被制作了, 以便各座桥梁二个舱板可能同时被修造和被发射。当它来到二座最后桥梁的建筑, 几乎是在互相附近, 他们将被修造一个舱板一次由于空间制约在扶垛。水力推挤的和制动系统。这是是主要限制防止Dragados 简化任务由发射所有桥梁反对倾斜的空间, 并且恶劣的地面条件在扶垛。

虽然Polimon 认为他研究下坡发射必需的早先计划, 它只是在一个短的距离和总在艰难发射的开始。以及标准艰难方法能应付下坡发射的系统的要求导致了一个更多正面系统的发展, 包括刹车的起重器并且推挤起重器。每个段是26m 长并且舱板被连接到发射的系统的手段非常简单。各段被熔铸以临时孔在上部并且梁木箱的低部, 二特别做钢直立的东西被插入为发射的过程。钢直立的东西的低部, 延伸在段之下, 被连接到发射的起重器通过一定数量的60 毫米直径, 6米长高强度铁棍被连接在系列。

按标准，起重器-150 吨容量,600 毫米冲程高压起重器提供必需的力量- 被安置在扶垛在一个特别地被设计的' 支撑的块之后' 。二是临时支持被提供在扶垛和铸件细胞之间, 由滑冠上板材, 并且在码头的上面, 钢盖子被安装在罐轴承, 是固定的入位置为发射的做法。一旦桥梁是完全的, 舱板将被顶起, 这些板材被去除和轴承被发布为正常服务。

在建造之前, 工程师计算必须被移动的总重量- 段的适当的数量加上发射的前端- 并且并且计算必须被克服的摩擦。这些价值允许工程师确定多少装载他们需要在起重器为了达到发射。600 吨是可得到从四台起重器在各个发射系统, 但他们只将需要大约440 吨至多的队估计。最大值和极小值被设置为各发射, 并且这被编程入PLC 控制单位为液压机构。最大值象极小值正重要, 既使当发射上升, 因为如果许多装载必需, 这能是某事是错误的征兆。如果最大值超出, 系统被编程自动地停止, 提示工程师检查一切进步对计划。在各个码头上面是被使用保留发射在正确对准线的一对侧向指南。

摩擦的作用和起重器的参差不齐的冲程可能导致舱板移动任何东西60mm 离线。Carlos Polimon 解释, 乘员组发现了系统非常容易经营, 并且他们达到

一段发射每星期在各个舱板- 或52m 舱板总共。发射每星期一发生, 以concreting 下段以下星期三发生和星期五。在10m/hour 附近的发射的速度达到得这里, 并且这非常有利地和最佳费率是4,5m/hour 发射的早先项目相比。铸件区域被设定在每个的扶垛之后结构, 并且各个区域有一套模板为熔铸26m 长的段。一台塔起重机服务各套模板; 一在二之间不会给充足的灵活性。模板- 从制造商仙子- 被设计了以便它可能被重复利用在所有桥梁, 尽管在计划曲度上的区别在他们之间。模板进来三个模块组成充分的长度段, 用可能考虑到曲线的不同的连接元素。操作的效率来自事实醒目的过程被自动化- 外面模板要诀向外在支持它的水力起重器, 和内在模板可能被运输在段外面在跑沿临时路轨在段的中心线的一辆小台车。另外的复杂化为铸件过程是, 外部岗位拉紧是包含的, 要求内在模板的适应。

第一桥梁的建筑将担当有点准备为必须被发射下坡的舱板。而且必须启动排液装置.在不动杆改变排液方式之前,它有机会与其他的工作进程同步.对于这部分工作,制动力相对于仅仅依靠机构自身的能力来制动是更好的选择.因此,柱塞将会与两个保持不动的部分一切被重新排列,这点类似于标准的排液程序,并且残存在背部的液体将会被一同排净.以上两点,就是所说的液压缸制动,并且钢杆将会反馈所有的载荷,这些载荷将会从前端的液压缸反馈到后端制动缸上. 千斤顶的负荷都将继续发挥在其他部分到位千斤顶将得到充分释放,而且必须让他们可以收回.

站点职员将有一次机会习惯所有建筑过程的其它部份在他们必须应付修改过的发射的做法之前。为这工作的部分, 它是确切, 正面刹车的力量必需, 而不是依靠摩擦减慢单位下来。结果, 起重器将被重新整理, 与二残余在扶垛, 至于为标准发射做法, 和其它二被安置在段的后方被发射。这两个作为刹车的起重器, 并且钢标尺一直将被哺养从向前起重器通过这些起重器和回到调动装载起重器在刹车的起重器之后。装载调动起重器利用保留段到位当其它起重器是充分地延长和需要被发布以便他们可能被缩回。

前端补救系统。前端防护系统.在排液系统的旁边液压机同样安装在排液系统的前端.两个柱塞与一个40吨容量并且有400mm缓冲能力的装置能够在柱塞前端部分到达前极限位置时纠正约300mm的偏差.这个偏差是有与两端的极限

位置相差52m的相对差距引起的.

综合系统—创造性的解决方案与应用技巧.环行通道方案作为工程样板与高压液压装置想结合的重要的解决方案.每四个缸与其相应的端盖有着不同的特点,比如倾斜度,交叉方式和弯曲度,但是液压综合系统的柔性设置足以克服这些不同.,但是液压综合系统的柔性设置足以克服这些不同。

附录Ｂ

Hydraulic Engines①

Water falling from one level to a lower one is used to drive machines like the water wheel and the turbine. The difference in height between the highest and the lowest level is called the head. The amount of work produced per pound of falling water is proportional to the head. Water power can be produced in this way from many natural sources, such as waterfalls and dammed rivers. Where no natural sources are available, an artificial reservoir can be made. When energy is plentiful, it is used to pump water into the reservoir; the water is then available as a power source to drive turbines when energy becomes scarce.

In driving certain industrial hydraulic machines an apparatus called an accumulator is employed to supply high power for short periods of time. One type consists essentially of a cylinder enclosing a piston loaded with weights. When water is slowly pumped into the cylinder, the piston and weights are forced up to a position where they are held. When they are released, they force the water out of the cylinder rapidly, providing the machine with hydraulic power.

Hydraulic machines are operated by a fluid, especially water, under pressure. They have wide applications in fields of engineering like: earth moving, mining industry, construction machinery, automotive engineering, textile industries, power plants, agricultural machinery etc.

Hydrostatic Devices

Water or oil under pressure is commonly used as a source of power for many types of presses, riveting machines, capstans, winches, and other machines. The hydraulic press, or hydrostatic press, was invented by Joseph Bramah and is therefore sometimes called the Bramah press. It consists essentially of two cylinders each filled with liquid and each fitted with a piston; the cylinders are connected by a pipe also filled with the liquid. One cylinder is of small diameter, the other of large diameter. According to Pascal lows

①本附录原文引自Kon W M,Tan S T.Proceedings of International Conference on Manufacturing Automation,HongKong,2002[z].HongKong:University of Hong Kong,2002. pressure exerted on the smaller piston is transmitted undiminished through the liquid to the surface of the larger piston, which is forced upward. Although the pressure (force per unit of area) is the same for both pistons, the total upward force on the larger piston is as many times greater than the force on the smaller piston as the area of the larger piston is greater than the area of the smaller piston. If, for example, the smaller piston has an area of 2 sq in. and a force of 100 lb is exerted on it, then the force on the larger piston having an area of 50 sq in. would be 2,500 lb (100×50/2=2,500). However, when the pistons move, the distance the smaller piston travels is proportionately greater than the distance the larger piston travels, satisfying the law of conservation of energy. If the smaller piston moves 25 in., the larger one will only move 1 in. The hydraulic press is used, for example, to form three-dimensional objects from sheet metal and plastics and to compress large objects.

The hydraulic jack, also an application of Pascal's law, is used to exert large forces or to lift heavy loads. Like the hydraulic press it consists essentially of two different-sized pistons contained in cylinders that are connected by a pipe. When the smaller piston is moved back and forth by a handle connected to it, it pumps a liquid into the cylinder of the larger piston, forcing the larger piston to move. In this way a weak force applied to the smaller piston can raise a heavy load on the larger one. The hydraulic elevator is also an application of Pascal's law.

HYDROSTATIC PRESSURE

Hydraulic Press is a machine in which a large force is exerted on the larger of two pistons in a pair of hydraulically coupled cylinders by means of a relatively small force applied to the smaller piston. They display superior performance through innovative ideas. The hydraulic presses range from 5 Tons to 5000 Tons capacity.

Operation Modes

The hydraulic presses have specific operation modes :

¤ Fully Automatic 'PLC'-Controlled

¤ Contractors/ Relay based

Frame Structures

The frame structures of these presses are:

¤ 'H' TYPE OR fabricated 4-column type

¤ 'C' type

¤ 4-pillars (Hard chrome pillars type)

Applications

The hydraulic presses have exclusive applications in the following spheres:

1.Deep drawing operations;

2.Blanking and Punching;

3.Riveting, Stamping and Pressing;

4.Powder Compacting;

5.Other applications like: FRP, SMC, DMC, Rubber Plastics etc.

Salient Features of hydraulic presses:

1.These presses provide fast approach slow pressing & fast return speeds. The change in speed can be manually preset to take place at any point of the stroke with the help of limit switches / proximity switches.

2.The frame is fabricated by ultrasonically tested quality profiles & plates of suitable thickness to with stand the load & longer life of the press. The frames are stress-relieved.

3.Maximum frame rigidity is achieved through computer aided frame design &

finite element analysis.

4.Extra long, precision machined & hardened guides to face slides offer exceptional accuracy & alignment which further reduced to wear.

5. In blanking or punching hydraulic presses a damping system can be fitted. This effectively reduces breakthrough noise & tool wear normally generated by such operations.

6.The low noise hydraulic power pack unit is designed as per international practices & assembled with internationally reputed make components. The presses are designed as per ISI guidelines, hence standard seals, bushes are used.

7. "Programmable logical controls" (PLC) is provided in our presses of international standard make i.e. ABB/Allen-Bradley/Siemens/Telemacqnice / keyance, offering maximum production flexibility & Full compatibility with international standards. 8.Precise machining of the structural members is done after normalising to get the required accuracies like parallelism between platen & bed & right angularity between bed and the moving platen.

9. Lubrication: Ram slides / guides/ guide bushes are lubricated from a centralised lubrication arrangement.

10. Moving platen: It is a fabricated, heavy duty, tested welded plate construction for highest stiffness under heavy loads. The whole platen is stress-relieved after welding. 'T' slots provided in the platen are as per DIN standards. Hydraulic or mechanical ejector pins to operate from inside the ram is also provided as optional on request or depending on the application.

11. Die transfer rails or bolster sliding arrangement is also provided as optional in front side of the press for heavy tools applications.

Types:

C frame type presses:

1.These presses offers maximum access to tool area for tool changing & component feeding aplications.

2. Range : 5 Tons to 300 Tons capacity.

3. Slides guidance can be either twin pillars type or face slides.

4.Hydraulic power pack is inbuilt & all valves are manifold mounted for easy & quick maintenance & a pressure relief valve protects against overloading of the press.

5. Additional equipments:

a. Ejectors in either the slide or under the press bed.

b. Die cushioning arrangement for deep drawing.

Hard chrome pillars type presses:

The guidance of this press offers excellent slide accuracy of the moving ram. Platen, resulting in reduced tool wear & an increased tool life.

Slide move on larger size phosphorous bronze / ultra bronze bearing mounted at each corner with suitable lubrication arrangement a proper sealing arrangement at both side of each bush is also provided.

PRINCIPLES OF HYDROSTATIC PRESSURE

In chapter 9 you found out that all fluids exert pressure in all directions. That’s simple enough. How great is the pressure? Try a little experiment. Place a pile of blocks in front of you on the table. Stick the tip of your finger under the first block from the top. Not much pressure on your finger, is there? Stick it between the third and fourth blocks. The pressure on your finger has increased. Now slide your finger under the bottom block in the pile. There you will find the pressure is greatest. The pressure increases as you go lower in the pile. You might say that pressure increases with depth. The same is true in liquids. The deeper you go, the greater the pressure becomes. However, depth isn’t the whole story.

Suppose the blocks in the preceding paragraph were made of lead. The pressure at any level in the pile would be considerably greater. Or suppose they were blocks of balsa wood-then the pressure at each level wouldn’t be as great. Pressure, then, depends not only on the depth, but also on the weight of the material. Since you are dealing with pressure—force per unit of area, you will also be dealing with weight per unit of volume-or density.

When you talk about the density of a substance, you are talking about its weight per cubic foot or per cubic inch. For example, the density of water is 62.5 pounds per

cubic foot; the density of lead is 710 pounds per cubic foot. However, to say that lead is heavier than water isn’t a true statement. For instance, a 22-caliber bullet is the same density as a pail of water, but the pail of water is much heavier. It is true, however, that a cubic foot of lead is much heavier than a cubic foot of water. Pressure depends on two principles-depth and density. You can easily find the pressure at any depth in any liquid by using the following formula:

P= H x D

in which

P = pressure, in lb per sq in. or lb per sq ft

H = depth of the point, measured in feet or inches

And

D = density in lb per cu in. or lb per cu ft

Note: If you use inches in your computation, you must use them throughout; if you use feet, you must use them throughout.

What is the pressure on 1 square foot of the surface of a submarine if the submarine is 200 feet below the surface? Using the formula:

P= H x D

P= 200 x 62.5 = 12,500 lb per sq ft

Every square foot of the sub’s surface that is at that depth has a force of more than 6 tons pushing in on it. If the height of the hull is 20 feet and the area in question is between the sub’s top and bottom, you can see that the pressure on the hull will be at least (200 – 10) x 62.5 = 11,875 pounds per square foot. The greatest pressure will be (200 + 10) x 62.5= 13,125 pounds per square foot. Obviously, the hull has to be very strong to withstand such pressures.

About Hydraulic Cylinders

Hydraulic cylinders are actuation devices that utilize pressurized hydraulic fluid to produce linear motion and force. Hydraulic cylinders are used in a variety of power transfer applications. Operating specifications, configuration or mounting, materials of construction, and features are all important parameters to consider

when searching for Hydraulic cylinders .

Important operating specifications for Hydraulic cylinders include the cylinder type, stroke, maximum operating pressure, bore diameter, and rod diameter. Choices for cylinder type include tie-rod, welded, and ram. A tie-rod cylinder is a Hydraulic cylinders that uses one or more tie-rods to provide additional stability. Tie-rods are typically installed on the outside diameter of the cylinder housing. In many applications, the cylinder tie-rod bears the majority of the applied load. A welded cylinder is a smooth Hydraulic cylinders that uses a heavy-duty welded cylinder housing to provide stability. A ram cylinder is a type of Hydraulic cylinders that acts as a ram. A hydraulic ram is a device in which the cross-sectional area of the piston rod is more than one-half the cross-sectional area of the moving component. Hydraulic rams are primarily used to push rather than pull, and are most commonly used in high pressure applications. Stroke is the distance that the piston travels through the cylinder. Hydraulic cylinders can have a variety of stroke lengths, from fractions of an inch to many feet. The maximum operating pressure is the maximum working pressure the cylinder can sustain. The bore diameter refers to the diameter at the cylinder bore. The rod diameter refers to the diameter of the rod or piston used in the cylinder.

Choices for cylinder configuration are simple configuration or telescopic figuration. A simple configuration Hydraulic cylinders consists of a single cylindrical housing and internal components. A telescopic configuration Hydraulic cylinders uses "telescoping" cylindrical housings to extend the length of the cylinder. Telescopic configuration cylinders are used in a variety of applications that require the use of a long cylinder in a space-constrained environment. Hydraulic cylinders can be single action or double action. A single action Hydraulic cylinders is pressurized for motion in only one direction. A double action Hydraulic cylinders can move along the horizontal (x-axis) plane, the vertical (y-axis) plane or along any other plane of motion. Choices for mounting method include flange, trunnion, threaded, clevis or eye, and foot. The mount location can be cap, head, or intermediate. Materials of construction include steel, stainless steel, and

aluminum. Common features for Hydraulic cylinders include integral sensors, double end rod, electro- Hydraulic cylinders and adjustable stroke.

Hydraulic cylinders are actuation devices that use pressurized hydraulic fluid to produce linear motion and force. Hydraulic cylinders are used in a variety of power transfer applications.

The difference between air and Hydraulic cylinders is the manner by which they are powered. While air cylinders generate linear motion and force via pneumatic power, Hydraulic cylinders use pressurized fluid. Hydraulic cylinders are available in three main types (with custom and miniature Hydraulic cylinders also available): tie-rod, welded and ram.

Tie-rod Hydraulic cylinders use one or more tie-rods to provide additional stability. Tie-rods are typically installed on the outside diameter of the cylinder housing. In many applications, the tie-rods in these precision Hydraulic cylinders bear the majority of the applied load. Welded cylinders provide smooth motion because of their heavy-duty welded cylinder housing, which provides stability. Hydraulic rams have a cross-sectional area of the piston rod, which is more than one-half the cross-sectional area of the moving component. Hydraulic rams are primarily used to push rather than pull, and are most commonly used in high-pressure applications.

In addition to their type, Hydraulic cylinders can be differentiated based upon their configuration. The two main configurations are simple and telescopic (again custom Hydraulic cylinders configurations are available). Simple configuration Hydraulic cylinders consist of a single cylindrical housing and internal components. This is the basic Hydraulic cylinders design used by most Hydraulic cylinders manufacturers. Telescopic Hydraulic cylinders use "telescoping" cylindrical housings to extend the length of the cylinder. Telescoping Hydraulic cylinders are used in a variety of applications that require the use of a long cylinder in a space-constrained environment.

In terms of motion, Hydraulic cylinders can be of single action or double action design.

Single action cylinders are pressurized for motion in only one direction. A spring

is frequently used to bring the cylinder piston back to the original position. Double action Hydraulic cylinders can move along the horizontal (x-axis) plane, the vertical (y-axis) plane or along any other plane of motion. Both sides of cylinder piston can be pressurized for reversible motion. Force ratings can differ somewhat in opposite directions.

Components of a hydraulic system

The power supply unit provides the necessary hydraulic power –by converting the mechanical power from the drive motor.

1.Power supply section

The most important component in the power supply unit is the hydraulic pump. This draws in the hydraulic fluid from a reservoir (tank) and delivers it via a system of lines in the hydraulic installation against the opposing resistances. Pressure does not build up until the flowing liquids encounter a resistance. The oil filtration unit is also often contained in the power supply section. Impurities can be introduced into a system as a result of mechanical wear, oil which is hot or cold, or external environmental influences. For this reason, filters are installed in the hydraulic circuit to remove dirt particles from the hydraulic fluid. Water and gases in the oil are also disruptive factors and special measures must be taken to remove them. Heaters and coolers are also installed for conditioning the hydraulic fluid. The extent to which this is necessary depends on the requirements of the particular exercise for which the hydraulic system is being used.

The reservoir itself also plays a part in conditioning the hydraulic fluid:

--Filtering and gas separation by built-in baffle plates,

--Cooling through its surface.

2.Hydraulic fluid

This is the working medium which transfers the prepared energy the power supply unit to the drive section (cylinders or motors). Hydraulic fluids have a wide variety of characteristics. Therefore, They must be selected to suit the application in question. Requirements vary from problem to problem. Hydraulic fluids on a mineral