首页 闭式液压系统介绍及使用

闭式液压系统介绍及使用

举报
开通vip

闭式液压系统介绍及使用 DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 液压技术座谈会 (闭式液压系统介绍及使用) Zhang Xin(张新) DCCN-SVH/Pk Dec.13th.2010 2© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposa...

闭式液压系统介绍及使用
DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 液压技术座谈会 (闭式液压系统介绍及使用) Zhang Xin(张新) DCCN-SVH/Pk Dec.13th.2010 2© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 座谈 内容 财务内部控制制度的内容财务内部控制制度的内容人员招聘与配置的内容项目成本控制的内容消防安全演练内容  闭式液压系统构成  A4VG180EP泵介绍  A6VM160EP马达介绍  管路安装  系统清洁度保证  A4VG180EP泵常见故障的诊断及排除  A6VM160EP马达常见故障的诊断及排除  问题讨论 3© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 何谓闭式液压系统 工作介质(液压油或其他)从执行机构直接回到泵 4© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 液压系统都需要安全保护元件 安全阀 5© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 任何液压泵和马达工作时都有漏损(散热,润滑) 增加泄油管路 6© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 因为漏损且为保证执行机构连续平稳运转,系统需要补油 增加补油泵和 补油阀 7© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 增加变量机构以实现泵的排量和输出方向的变化 增加变量控制 阀及变量活塞 8© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 闭式系统易发热,故对于大排量泵和马达构成的闭式系 统,常常会增加冲洗油路以加速热交换 增 加 冲 洗 阀 9© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 10© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 闭式液压系统介绍 方向控制阀: 规格小 => 仅进行先导控制;(开式系统中的规格大) 过滤器和散热器:规格小 => 只需与补油泵的流量匹配; 液压油箱:小尺寸 => 只需与补油泵流量匹配; 运转速度:补油泵限制=> 补油泵的结构及连轴套上的平键 安装位置:任意位置 驱动:可逆的 => 泵马达工况可逆,可实现静压制动 闭式系统的特点 11© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EPD泵介绍 轴向柱塞泵工作原理 容积泵一种 密封容腔 容腔体积可变 12© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EPD泵介绍 轴向柱塞泵工作原理 13© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EPD泵介绍 A4G180EP泵工作原理 2 EP控制 阀 1主泵 4 变量活 塞 5 高压溢流 阀(带补油 阀) 6 低压溢 流阀/补 油阀 3 压力切断 阀 过滤 器带 冷启 动阀 及指 示器 2 3 4 5 6 X1,X2 R Ps MA,MB T G 14© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EPD泵介绍 轴端无应力安装 => 安装时不可以敲击 轴端,放置时不可以轴端着地;  检查泵的旋向:与电机(发动机)一致 保证油液清洁度 清洁度等级:至少ISO4406 20/18/15 油液温度较高时(90度~115度): 至少ISO4406 19/17/14 A4G180EP泵使用要求 保证同轴度 => 联轴器安装时,要根据 生产厂家的要求保证同轴度; 吸油压力:不能低于0.8bar(绝对压 力),表测压力不低于-0.2bar; 壳体压力:不能高于3bar(绝对压 力),表测压力不高于2bar 15© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EPD泵介绍 壳体加油,排气:向壳体内加满干净的 液压油,从高处的油口排气(第一次试车、 长时间不用或更换油管后,启机前) 泄油管连接: 接在泵壳体上方的T口,直接回油箱; 接头要符合欧洲标准的超轻型系列 油管选用单层钢丝的低压油管 吸油过滤:尽可能不要采用吸油过滤; 如果要用吸油过滤,过滤器精度要大于 100U,通流量大于补油泵流量的2.5倍; 有关清洁度的保证措施,后面专门论述 A4G180EP泵保证措施 16© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达介绍 轴向柱塞马达工作原理 17© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达介绍 轴向柱塞马达工作原理 18© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达介绍 A6VM160EP马达工作原理 带冲洗阀 19© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达介绍 轴端无应力安装 => 安装时不可以敲击 轴端,放置时不可以轴端着地;防止顶轴 保证油液清洁度 清洁度等级:至少ISO4406 20/18/15 油液温度较高时(90度~115度): 至 少ISO4406 19/17/14 A6VM160EP马达使用要求 保证同轴度 => 联轴器安装时,要根据 生产厂家的要求保证同轴度; 壳体压力:不能高于3bar(绝对压 力),表测压力不高于2bar 20© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达介绍 A6VM160EP马达使用要求  壳体加油:试车时壳体内要加满干净的 液压油,将马达壳体内气排净 泄油管:要求同前面泵的要求 21© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180泵与A6VM160马达组成的闭式液压系统 旁通阀 2bar X1X2 变量活塞控 制油测量口 R壳体压力测量口 B测高压溢流阀 机械零位调整杆 A测高压溢流阀 G补油压力测量口 A测高压测量 B侧高压测量 低压溢流阀 泵上各油口尺寸 各测量口用压力表量程 22© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 管路准备及安装时一般性要求 在储存、运输的过程中,油管开口要用干净的塑料堵等密封保护; 最好使用没有经过涂敷的无氧化皮的; 锯完后,应仔细去除毛刺; 冷态折弯 尽可能避免焊接接头。若无法避免,在焊接时要考虑焊杂的易处理; 不要使用棉纱和废布清理管路,最好使用稠缎; 对于液压油箱,一定要认真处理掉焊渣,并用面沾干净油箱的内部 23© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 吸油、泄油和回油管路安装的具体要求 任何时候,吸油和泄油管都要在液面 下至少2.5倍的管子直径;但不能小于 100mm;(防止起泡 ) 泄油管(或回油管)要高于吸油管, 并注意:回油不可以直接被吸走 吸油管,回油管和泄油管的油口间的 距离要大于200mm; A B Emin≥ 2.5倍管径(100mm) Amin≥ 200mm Bmin≥ 200mm 24© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 吸油管的不良安装  最少有2.5倍油管直徑的距離 隔板必須安裝 吸油区的油液不可 以急速流动 紊流区 長而平放的吸油管 (考虑支架) 平切口的油管 (45度切口) 产生气泡 (考虑直管) P suction 25© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 吸油管的不良安装  P suction 吸油區內油液不可急 速流動 calm oil in suction chamber 紊流區 turbulent zone Allg. 090.10 VST1/VST6 09.AA 必須安裝隔板 baffle absolutely necessary 最少有2.5倍油管直徑 的距離 at least 2.5 pipe i.d. minimal distance 26© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 吸油管的不良安装 例一、 只接在油箱壁 case 1 only grommet 例二、 油管太短 case 2 pipe too short 例三、 太接近吸油管口 case 3 too close to the suction inlet 液位 oil level 液位變化 swinging level 注意! 回油管必須經常低於最底 液位 ATTENTION! Return line must always end under the minimum oil level Allg. 090.11 VST1/VST6 06.AA 27© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 吸油管喉箍设计 兩個喉碼為90°分隔開 2 hose clamps 90° offset 尖角會損壞軟管 sharp chamter can damage hose 型成氣泡(扰流形成气泡) creation of air pocket 有利流向的最佳設計 optimised design for every flow 圓角 round chamter Allg. 090.6 VST1/VST6 06.AA 28© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 吸油管喉箍设计 氣谷 longitudinal airgap 使用兩個喉碼時必須 分開安裝 When using two hose clamps, mounting needs to be offset 安裝一對喉碼須以 90°分隔開 Hose clamps have to be assembled with a set of 90° 29© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统管路及油箱的安装 无应力安装 折弯半 径3倍 于管径 30© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 保证系统油液清洁度的重要性 油液污染 元件磨损 元件堵塞 吸空 元件损坏 系统性能下降/ 动作失灵 油液污染 系统吸空 液压系统 两大天敌 31© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 液压系统污染的来源 1. 外部污染 2. 装配时造成污染 3. 启动系统时造成的污染 4. 内部污染 5. 磨损 6. 新的油液 7. 维修造成的污染 32© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 10um的颗粒放大100倍 10um的颗粒与人头发放大100倍图像 人头发直径约75um 热 人肉眼可分 辨的最小尺 寸为40um 33© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 常用液压件间隙尺寸 34© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 两种尺寸的颗粒危害最大 两 5um 元件堵塞 15um 元件磨损 35© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 不同清洁度液压油比较 油桶里新的液压油 ISO4406 22/20/18 级 (NAS12级) 新安装系统内的污染 ISO4406 23/22/20 (大于NAS12级) 新油液是不 干净的 热 热 36© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 不同清洁度液压油比较 经常规过滤器过滤的液压油 ISO4406 20/18/16 (NAS 9级) 经过3 〉200的精过滤器 过滤的油液 ISO4406 14/13/11 (NAS4级) 柱塞泵和 马达的最 低要求 热 热 37© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 衡量过滤器的三大指标  过滤精度  压差特性  纳污能力 38© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 国际通用的过滤精度表示方法 x = 75 的X值 过滤精度  反应的是过滤器对不同直径颗粒的过滤能力  为检验其性能,人为规定的指标;是在特定的条件下通过试验 测得的;  这一指标越高,其过滤能力越强;但它无法表征出过滤器在系 统中的真实净化能力(受多种因素影响) 39© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 过滤精度 40© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 过滤精度举例 7.80 10 - 2 14.6 100 13.7 75 18.715.9颗粒尺寸 1000200平均过滤比 该过滤器的精度为:14 m该过滤器的精度为:14 m 油液的清洁度 过滤器精度≠诉 两者没有一一对应的关系 41© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 压差特性  进出口的压力差,是油液黏度、流量、 孔径、孔形状、过滤面积的函数  压差越小越好 42© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 纳污能力  进出口的压力达到极限压差时,过滤器吸纳的 污物的量;  它是衡量过滤器寿命的重要指标 过滤器的滤芯不可以清洗,只 能更换 43© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 系统油液清洁度的控制 保证油液清洁度建议 安装前所有管路进行清洗; 油箱内一般不要涂油漆,安装前仔细去除焊渣,用面沾,最好采用不锈钢油箱; 换油时要彻底清洗油箱和管路,加油时采用过滤精度10um的滤油机加注; 吸油管、泄油管、回油管要正确安装(方法参考前面);必要时可在系统的高处 设置放气阀; 保证油箱温升不超过液压油规定,一般不得超过70度(超过80度后,每增加10 度,元件损坏的速度呈指数级增加); 及时更换不良密封(防止系统进气),及时更换水冷却器等(防止系统进水); 44© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EP泵故障诊断  泵异响 a〉油液不足;吸油不畅 b〉磨损严重,内泄过大; c〉系统排气不彻底; d〉连轴器安装不合适; 泵工作无压力或流量异常 a〉电气故障(电磁阀未能送上电) b〉补油压力异常(补油溢流阀卡滞,补油泵磨损) c〉磨损,内泄过大; d〉切断压力设定不合适(或切断阀芯被异物卡住) e〉马达工作异常造成(马达磨损,冲洗阀异常) 45© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A4VG180EP泵故障诊断 泵壳体温度过高 a〉内泄,泄油管堵塞; b〉磨损; c〉溢流阀故障; 46© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达故障诊断 马达异响 a〉油液不足; b〉磨损严重,内泄过大; c〉超速; d〉过载,溢流阀溢流; e〉制动响声; 马达工作无力或压力异常 a〉磨损内泄过大; b〉溢流压力设定不合适(或阀芯被异物卡住) c〉泵工作异常造成; 47© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 A6VM160EP马达故障诊断 马达无法变排量 a〉EP阀电器故障; b〉控制油路堵塞; c〉变量机构卡滞; d〉变量活塞密封磨损; 马达壳体温度过高 a〉内泄,泄油管堵塞; b〉磨损; c〉排量选择不合适,过小; 48© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 问题讨论 49© All rights reserved by Bosch Rexroth AG, even and especially in cases of proprietary rights applications. We also retain sole power of disposal, including all rights relating to copying, transmission and dissemination. DCCN/SVH-001-PR-F15 Edition: 1 2009-12-10 结束
本文档为【闭式液压系统介绍及使用】,请使用软件OFFICE或WPS软件打开。作品中的文字与图均可以修改和编辑, 图片更改请在作品中右键图片并更换,文字修改请直接点击文字进行修改,也可以新增和删除文档中的内容。
该文档来自用户分享,如有侵权行为请发邮件ishare@vip.sina.com联系网站客服,我们会及时删除。
[版权声明] 本站所有资料为用户分享产生,若发现您的权利被侵害,请联系客服邮件isharekefu@iask.cn,我们尽快处理。
本作品所展示的图片、画像、字体、音乐的版权可能需版权方额外授权,请谨慎使用。
网站提供的党政主题相关内容(国旗、国徽、党徽..)目的在于配合国家政策宣传,仅限个人学习分享使用,禁止用于任何广告和商用目的。
下载需要: 免费 已有0 人下载
最新资料
资料动态
专题动态
is_019328
暂无简介~
格式:pdf
大小:1MB
软件:PDF阅读器
页数:49
分类:
上传时间:2011-04-12
浏览量:15