关 键 词：

机械毕业设计论文

资源描述：

工艺夹具毕业设计44车用空调用压缩机充注体加工工艺规程及夹具设计（大批量生产）,机械毕业设计论文

内容简介：

机械加工工序卡片 产品型号 空调 零（部件）图号 产品名称 空调 零（部件）名称 充注体 共 6 页 第 1 页 车间 工序号 工序名 材料牌号 金工 VI 粗铣 毛坯种类 毛坯外形尺寸 每毛坯可制件数 每台件数 铝件 1 1 设备名称 设备型号 设备编号 同时加工件数 机床 C6140 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工序工时 /s 准终 单件 工步号 工步内容 工艺装备 主轴转速 /r s-1 切削速度 /m min-1 进给量 /mm r-1 背吃刀量 /mm 进给次数 工步工时 /s 机动 辅助 1 粗车 外圆车 刀、游标卡尺、千分尺 500 0.1 10.5 1 1 7.2 设计 (日期 ) 审核 (日期 ) 标准化 (日期 ) 会签 (日期 ) 标记 处数 更改文件号 签字 日期 标记 处数 更改文件号 签字 日期 nts 机械加工工序卡片 产品型号 空调 零（部件）图号 产品名称 空调 零（部件）名称 充注体 共 6 页 第 2 页 车间 工序号 工序名 材料牌号 金工 VII 粗铣 K70A 毛坯种类 毛坯外形尺寸 每毛坯可制件数 每台件数 铝件 1 1 设备名称 设备型号 设备编号 同时加工件数 卧式铣床 X6022 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工序工时 /s 准终 单件 工步号 工步内容 工艺装备 主轴转速 /r s-1 切削速度 /m min-1 进给量 /mm r-1 背吃刀量 /mm 进给次数 工步工时 /s 机动 辅助 1 粗 车 端 面 铣刀、游标卡尺、 千分尺 150 0.042 0.15 2 1 7.5 设计 (日期 ) 审核 (日期 ) 标准化 (日期 ) 会签 (日期 ) 标记 处数 更改文件号 签字 日期 标记 处数 更改文件号 签字 日期 nts 机械加工工序卡片 产品型号 空调 零（部件）图号 产品名称 空调 零（部件）名称 充注体 共 6 页 第 3 页 车间 工序号 工序名 材料牌号 金工 VIII 精铣 K70A 毛坯种类 毛坯外形尺寸 每毛坯可制件数 每台件数 铝件 1 1 设备名称 设备型号 设备编号 同时加工件数 卧式 车 床 C6140 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工序工时 /s 准终 单件 工步号 工步内容 工艺装备 主轴转速 /r s-1 切削速度 /m min-1 进给量 /mm r-1 背吃刀量 /mm 进给次数 工步工时 /s 机动 辅助 1 精车 13H12 孔的两面 外圆车 刀 、游标卡尺、内径 千分尺 150 0.054 0.12 1 1 18.6 设计 (日期 ) 审核 (日期 ) 标准化 (日期 ) 会签 (日期 ) 标 记 处数 更改文件号 签字 日期 标记 处数 更改文件号 签字 日期 nts 机械加工工序卡片 产品型号 空调 零（部件）图号 产品名称 空调 零（部件）名称 充注体 共 6 页 第 4 页 车间 工序号 工序名 材料牌号 金工 IX 精镗 K70A 毛坯种类 毛坯外形尺寸 每毛坯可制件数 每台件数 铝件 1 1 设备名称 设备型号 设备编号 同时加工件数 卧式 车 床 C6140 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工序工时 /s 准终 单件 工步号 工步内容 工艺装备 主轴转速 /r s-1 切削速度 /m min-1 进给量 /mm r-1 背吃刀量 /mm 进给次数 工步工时 /s 机动 辅助 1 保证图示各尺寸 车 刀 、游标卡尺、 内径 千分尺 150 0.047 3.33 1 1 6.6 设计 (日期 ) 审核 (日期 ) 标准化 (日期 ) 会签 (日期 ) 标记 处数 更改 文件号 签字 日期 标记 处数 更改文件号 签字 日期 nts 机械加工工序卡片 产品型号 空调 零（部件）图号 产品名称 空调 零（部件）名称 充注体 共 6 页 第 5 页 车间 工序号 工序名 材料牌号 金工 X 钻 K70A 毛坯种类 毛坯外形尺寸 每毛坯可制件数 每台件数 铝件 1 1 设备名称 设备型号 设备编号 同时加工件数 立式钻床 Z535 立式钻床 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工 序工时 /s 准终 单件 工步号 工步内容 工艺装备 主轴转速 /r s-1 切削速度 /m min-1 进给量 /mm r-1 背吃刀量 /mm 进给次数 工步工时 /s 机动 辅助 1 钻孔 直柄麻花钻 、游标卡尺、 内径 千分尺 16.67 0.05 2.5 4 1 7.56 设计 (日期 ) 审核 (日期 ) 标准化 (日期 ) 会签 (日期 ) 标记 处数 更改文件号 签字 日期 标记 处数 更改文件号 签字 日期 nts 机械加工工序卡片 产品型号 空调 零（部件）图号 产品名称 空调 零（部件）名称 充注体 共 6 页 第 6 页 车间 工序号 工序名 材料牌号 金工 XI 扩孔 K70A 毛坯种类 毛坯外形尺寸 每毛坯可制件数 每台件数 铝件 1 1 设备名称 设备型号 设备编号 同时加工件数 立式钻 床 Z535 立式钻床 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工序工时 /s 准终 单件 工步号 工步内容 工艺装备 主轴转速 /r s-1 切削速度 /m min-1 进给量 /mm r-1 背吃刀量 /mm 进给次数 工步工时 /s 机动 辅助 1 扩孔 铣刀、游标卡尺、千分尺 1.59 0.4 1.33 2 1 100.8 设计 (日期 ) 审核 (日期 ) 标准化 (日期 ) 会签 (日期 ) 标记 处数 更改文件号 签字 日期 标记 处数 更改文件号 签字 日期 nts 1 毕业实习 报告 一 实习的目的 及 意义 这次为期 一个月 的 毕业实习 是我们参与实践活动的很重要的一部分，在 张红霞 ， 李明 等老师的带领下我们见习了 黑龙江省农业机械工程科学研究院 ，毕业 实习作为一个重要的学习环节，其目的在于通过实习使我获得基本生产的感性知识，理论联系实际，扩大知识面；同时专业实习又是锻炼和培养学生业务能力以及素质的重要渠道，培养我们吃苦耐劳的精神，也是我们接触社会、了解产业状况、初步了解企业的基本方法和技能；体验企业工作的内容和方法。这些实际知识， 对我们今后的工作，都是十分必要的基础。 毕业实习是本科教学计划中所设置的重要实践性教学环节，是学生理论联系实际的课堂。 其目的在于通过实习使学生获得基本生产的感性知识，理论联系实际，扩大知识面 ;同时专业实习又是锻炼和培养学生业务能力及素质的重要渠道，培养当代大学生具有吃苦耐劳的精神，也是学生接触社会、了解产业状况、了解国情的一个重要途径，逐步实现由学生到社会的转变，培养我们初步担任技术工作的能力、初步了解企业管理的基本方法和技能 ;体验企业工作的内容和方法。 通过毕业实习，学生将所学过的理论知识与生产实际结合起来 ，特别是专业理论与具体的机械产品设计联系起来，分析生产实际中具体的机械生产设备的工艺、原理、结构、执行机构及控制系统，收集和获取与毕业设计题目有关的各种技术资料，为毕业设计作准备。 二 实习时间 及地点 实习时间： 2014.03.032014.04.04 实习地点：黑龙江省农业机械工程科学研究院 三 实习 单位 简介 黑龙江省农业机械工程科学研究院成立于 1958 年 3 月，位于哈尔滨市哈平路 156号，是我国成立较早、规模较大的省级综合性农机科研院所之一。经过五十余年的建设，已发展成为科技力量雄厚、科研手段先进、综合 实力较强、在国内外具有重要影响的知名农机科研机构。科研方向涵盖了粮食作物现代农业装备、经济作物现代农业装备、农田水利灌溉装备、畜牧业现代装备、农业智能化装备、农村能源工程技术装备、农业工nts 2 程咨询与设计及农业机械化战略研究等领域，设有农业部旱地农业装备技术重点实验室、黑龙江省现代农业装备重点实验室、黑龙江省种植业机械工程技术研究中心、黑龙江省农机新产品中试基地、博士后科研工作站，是国家农业装备产业技术创新战略联盟15 家首批发起单位之一、黑龙江省农业装备产业技术创新战略联盟牵头单位，拥有农业机械化、畜牧机械化和机 械电子工程三个省级领军人才梯队。 建院以来，始终把科技创新工作放在首位。先后取得科研成果 616 项，其中 200 余项获得国家部委、省、市和行业的科技成果奖励，获专利成果 195 项，培养了一批省内外知名专家。尤其是“十五”以来 黑龙江省农业机械工程科学研究院 为发展现代农业研发了一批具有国际先进水平的现代农机新装备，并在农业生产中大量应用，成为支撑黑龙江省农业机械化发展的关键装备，创造了显著的经济效益和社会效益，在我省建设新型农机装备制造业和千亿斤粮食产能巩固提高工程中发挥了重大作用，为促进农业增产增效和社会主义新农村 建设做出了重要贡献，被农业部授予全国农机化科技先进单位，连续三届荣获黑龙江省振兴经济奖，被省政府评为省级文明单位标兵和省科技系统先进集体。 四 实习内容 在老师的带领下，经过与黑龙江省农业机械工程科学研究院领导商量，我们在工厂参观实习，看了许多机器，如： 1DF 系列复式少耕整地机 、 1DSL-3600 型深松碎土联合整地机 、 1DF 系列复式少耕整地机 、 1DQ 系列全面耕耘机 、 1GZMN-324H5D5V5 型灭茬 、 马铃薯挖掘机 、 马铃薯施肥种植机 、 4T-1 型甜菜收获机 、 2SB-4 型气力式蔬菜播种机 、 计算机视觉排种器试验台 、 高适应性电子脉动器及其控制系统 、 WFS-喷雾性能综合试验台 、 DYP-435 型中心支轴式喷灌机 、 TX-75 型卷盘式喷灌机 等。 在了解许多机器的实物以及几何尺寸、重量、加工工艺等有关资料后，我们整理了资料，记在实习记录本上。在老师的带领下画出机构简图。分析运动原理，研究农业运行的经验、原理和常见的一些故障问题，通过学习，更加深刻理解农业方面的知识。 nts 3 图一 DSL-3600型深松碎土联合整地机 如图一所示该机器 适合我国北方土壤和耕作实际，一次进地能实现深松、除草、碎土、镇压等多种功能，作业后土壤表层细碎平整，底层致密，蓄水保墒效果好，可为播种创造优良的种床环境。深松铲柄由特种弹簧钢经严格的热处理工艺制成，工作时前后排深松铲会沿左右方向作弹性振动，深松阻力小，动土范围大，深松碎土效果好。 JPS-12 排种器试验台 1.试验台的工作原理 在田间测试播种机的排种性能时，播种机是随拖拉机的前进而运动的 ，试验台正相反，它是用种床带做种床，模拟播种机的田间工作速度进行运动，排种器在试验时固定不动，种床相对于排种器进行运动。这样就把播种机相对地面的运动转变为地面相对于播种机的运动，从运动学的相对性概念来说，只是一个参考坐标系转换问题，其效果是一样的。排种器在固定位置把种子排落在涂有油层的种床带上，图像采集处理系统对种床带上的种子进行实时地检测，从而达到输出各项排种性能指标的目的。 2.试验台的特点 通过借鉴、分析与总结国内外现有排种器试验台的基础上进行设计的，结构精巧，使用方便，基于计算机视觉技术，可 实现排种性能的实时检测。对于条播排种器，提供排量稳定性（能实现排种量的称重测量）和变异系数等检测指标；对于穴播排种器，提供穴距、穴粒数，实际穴距分布值，判定穴距合格率、穴粒数合格率等指标；对于精密排种器，提供精确的种子粒距（粒距测量平均误差 2mm）、合格指数、重播指数、漏播指数和变异系数等检测指标，并输出符合国家标准要求的试验数据和图表；可存储播种nts 4 录像，用于反复观察分析。 3.试验台性能指标 图二 项目 指标 备注 种床带速 度 km/h 1.5 12 种床带速度测量误差 % 0.5 排种轴转速 r/min 10 150 排种轴转速测量误差 % 0.5 风机输出的工作压力 KPa 0 5 正压 风机输出的工作压力 KPa -5 0 负压 种子粒距测量平均误差 mm 2 大豆、玉米 4.基本技术规格 图三 项目 指标 备注 电源 三相交流电源 作业功率消耗 kw 10 人工检测区 m 5 5主 要工作参数设计： 种床长度的确定 种床带前进速度的确定 排种盘转速的调速范围 种床带传送装置驱动电机功率的确定 nts 5 排种器驱动电机功率的确定 油泵的选择 油泵驱动电机的选择 6 试验台总体结构 试验台总体结构如图 1 所示，主要有台架，种床带装置，排种器安装架装 置 ,以及 5mm 厚，长宽不一的铁板。 型带输送带传动系统机架电动机排种器图 四 试验台总体结构简图 7.机械结构部分 种床带：采用无缝精密橡胶带，运行平稳，不打滑，振动小，噪音低，符合标准实验室环境的振动） 台架：底架由 63*63 角钢组合而成。装备双滚筒（主、从传动轮 有防跑偏结构），表面压纹，配置张紧机构（可调偏）；上下两层带下安置托辊，按不同位置间隔设置和噪音要求。在主传动轮和下层托辊等处分别设计可调刮油刮种板，以及集油回收管路，双层过滤筛（滤种、滤油），筛下置有集油箱，选用喷油齿轮泵从集油箱泵油到台架上的矩形喷油嘴，将油喷涂到种床带上，该油可有效黏附落下的种子，配有自动油温加热及控制装置，保持油路的最佳流动状态； 装备可升降刷子架（箅油）； 装备排种器万能安装架，架上装备排种轴驱动电机、减速器及传动机构等；除主体钢制框架外，其余各机架和结构部件均为不锈钢制，外部整 体安装仿形壳体和护板。 nts 6 8.综合操作台 以高性能计算机做测控主机（主机配置见计算机配置单），显示种床速度、排种轴转速，并对排种图像进行采集、处理和分析；配激光打印机，打印输出相应的排种性能试验报告。如图 2 所示。 马铃薯施肥种植机 1.主要结构和工作原理 该机主要由机架部分、排种机构、排肥机构、覆土机构和动力传动机构组成。 1、机架部分。主要由各种矩形管焊接而成，主要用于连接各类工作部件。 2、排种机构。主要由排种链、排种杯、排种主动链轮、排种被动链轮和排种筒等组成。 该机的排种机构采用杯升运式。排 种机构由种植机地轮通过链轮及链条驱动，在播种部分机架上安装有主动和被动两个排种链轮（主动链轮在下部，被动链轮在上部），两个链轮上有一条排种链条作椭圆形转动，在排种链条上固定有种杯，此链条从种子箱的中间穿过，当排种链作椭圆形转动时，种杯将种块升运到排种筒顶部，再从排种筒向下运动，将种块播种到开沟器开出的沟内。 3、排肥机构。主要由肥箱、排肥轮、输肥管及排肥轴组成。排肥轮由地轮通过链条及链轮驱动，肥箱中的化肥经排肥轮、输肥管排入开沟器开出的沟内。 4、覆土机构。该机覆土器采用犁铲式起垄机构，能一次性完成覆土、起 垄作业。 5、动力传动机构。主要由地轮、链轮和链条等组成，由拖拉机牵引，经地轮将动力传给机具。 性能特点 作业效率高，土壤条件适应性强，株距均匀，重播和漏播率低，株距和垄距调整方便，调整范围大 五 实习 心得 图 五 综合操作台 nts 7 为期 一个月的毕业 实习 结束了 ，在这次实习中，我学会了许多书本上没有的知识，了解许多工作经验，通过实践，使我的专业知识有了很大提高。现在我们即将踏入社会，这些实践性的东西对我们来说是至关重要的，它让我们脱离了书生的稚气，增加了对社会的感性认识、对知识的更深入的了解。在实习时我 亲身感受了所学知识与实际的应用， 生产 技术在机械制造工业的应用，精密机械制造在机器制造的应用等知识。 理论与实际的相结合，让我们大开眼界 也是对以前所学知识的一个初 审。 通过这次生产实习，进一步巩固和深化所学的理论知识，弥补以前 单一理论教学的不足，为 后续专业课学习和毕业设计打好基础。同时，收集了许多资料，丰富了农业机械知识，对我的毕业设计有很大帮助，这是在学校里学习不到的，在这次实习中我学会了相当多的有关农业方面知识，开阔了视野，为毕业设计收集了资料，为毕业设计奠定基础，使我对于自己的毕业题目很清晰，有了更大的信心，我相信我的设计会做的更好，收获 颇多，是我大学学习生涯中的重要一个环节，非常重要。 总之，虽然实习的时间很短，但对我来说，收获是很大的。我会更加珍惜我的学习，并且用实习的心得时时激励自己 ! ntsFOREIGN TECHNOLOGY MAIN DEVELOPMENT TRENDS IN THE GEAR PUMPS (SURVEY OF FOREIGN PATENTS) V. V. Burenin, V. P. Dronov, and A. I. Yakovlev DESIGN OF UDC 621.664n71 (047) Gear pumps are one of the most widely applied rotary pumps and are used in many branches of in- dustry to pump gasoline, diesel fuel, various oils, petroleum, and other liquids. Gear pumps have a number of advantages over other types of rotary pumps: they are simple in construction, reliable and have a long service life, are easy to operate, can operate at relatively high speeds, and are small and light in weight. Gear pumps are available with outside and inside meshing gears. Single stage two rotor gear pumps with outside meshing have received the widest acceptance since they have the simplest construction and are cheapest to fabricate. However inside meshing gear pumps are more compact. Development of gear pump design is proceeding along the following lines: increased reliability and service life of the pumps as a whole and the individual assemblies; use of new materials of construction; development of high head, high speed pumps, controlled throughput, and reversible direction of pumping; improving fabrication technology and reducing the costs of production and operation; and increasing the cavitation margin, the volumetric and mechanical efficiency. A gear pump with a special lubricating system for the gear journals 1 has been developed. The ends of three short journals enter three corresponding dead-endchambers. A fourth chamber is provided around the neck of the drive shaft. All four chambers are interconnected by passages in the shafts and chamber and with the suction line through a common passage. A valve is built into the common passage which main- tains a certain pressure in the chambers. During pressurized operation of the pump the journals are lubri- cated by liquid flowing through the clearances. A valve is provided connecting the lubricating chambers with the discharge line for lubricating the journals when the pump operates under no load and leakage is small. When pump discharge pressure is low this valve is kept open by a spring and liquid flows through it into the lubricating chambers. The valve closes on increasing pressure and lubrication occurs only due to leakage. The construction of a reversible gear pump with inside meshing is shown in Fig. 1 2. A cylindrical floating ring 2 is located in the casing 1. This ring has an eccentric internal bore and a radial slot. Lever 6 1 9 2 i 3 Fig. 1. Reversible gear pump with inside mesh- ing. 3 is located in this slot. Outer rotor 4 is mounted in the eccentric ring with inner rotor 5 connected to the drive shaft, located inside 4. Suction and dis- charge openings, connected with the corresponding suction and discharge lines, are provided in the pump housing which also has two pins 6, located 180 from each other, which limit the rotation of the floating ring. Liquid in the spaces between the teeth of the rotors is moved from the suction to the discharge line when the rotors turn. When the direction of shaft rotation is reversed the floating ring rotates in the same direction since it tightly encloses the outer rotor. The ring turns until the lever presses on the pin and opens up the split floating ring. The rotation of the floating ring changes the location of the ec- centric ring relative to the suction and discharge openings. This preserves the direction of liquid flow. An original reversible gear pump 3 is shown in Fig. 2. The two halves of the casing 3 and 8 and gears 4 and 10 are fabricated of Derlin plastic by Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 5, pp. 44-48, May, 1971. 9 1971 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publisher. A copy of this article is available from the publisher for $15.00. 445 ntsA-A A # 3-._._ 2 f -d A Fig. 2. Plastic gear pump. Fig. 3. Multigear pump. pressing on a casting machine. The diameter of journals 1, 2, and 9 is 0.3-0.4 of the diameter of the aver- age circumference of the gears. The large bearing surface allows the casing to have equal wall thickness throughout which results in uniform stress distribution and effective heat removal from the rubbing sur- faces. Lead gear 4 is rotated by the driver through shaft 7 which rotates in sliding bearing 5 and is sealed in the casing by sleeve 6. Liquid is supplied and discharged from the casing of the pump along channels 12 and 14. Openings 11 and 13 are provided between the gear teeth which supply pumped liquid to the support surfaces under pressure. The construction of the pump is simple and compact. A gear pump with double walled casing construction 4, designed for pumping corrosive liquids, is noteworthy. The internals of the casing in contact with the liquid are fabricated of corrosion resistant metals (stainless steel, titanium, tantalum) or porcelain and are simple in shape. The inner parts are pressed tightly together by the outer casing parts which are bolted. The suction and discharge nozzles are ce- mented to the outer casing. This cement solution is poured into the annular spaces between the nozzles and the outer casing parts through special openings. Pump construction is simple and well engineered. The relative simplicity of construction and operating reliability of two rotor single stage gear pumps is used as a basis for development of various designs of multistage, multirotor pumps which are compact, simple, and develop higher heads and have greater capacity. A patented gear pump for liquid oxygen 5 consists of two sections separated by a plate. Straight tooth drive and driven gears are located in the upper section while the lower section has herringbone gears. The upper section supplies liquid from its discharge nozzle along a passage to the inlet chamber of the lower section which delivers the liquid to the discharge nozzle. The upper section does relatively little work, functioning as a prepump, so that the liquid is not heated up significantly reducing the possibility of evaporation and cavitation in the bottom section. The high capacity of the bottom section and the small hold- up volume of the connecting passage also help reduce liquid evaporation and cavitation. The capacity of this pump, transferring liquid oxygen at -182 from a tank at 0.35 atm gage pressure to a chamber at 35 atm gage pressure, is 14 liters/min at a drive shaft speed of 600 rpm. A gear pump with a large solar gear and six small satellite gears located in the casing deserves mention 6. The point of contact of each satellite with the solar gear is in effect a separate pump. A spe- cial feature of this design is floating teeth in the solar gear alternating with fixed teeth, all of which are fabricated as part of the gear. The floating teeth of the solar gear improve the contact between the gear and the casing and reduce leakage improving efficiency and the operating pressure developed by the pump. Figure 3 shows the construction of an oil-filled gear pump with several intermeshing gears 7. Each pair of meshing gears represents a small pump. This design considerably reduces the number of gears required to create an equal number of pumping units compared to individual pumps with two gears each. A multigear pump for delivery and mixing of viscous liquid 8 is worth mentioning. The casing of this pump is formed by three plates. The middle plate is bored for gear installation. A central gear is mounted on the pump shaft. This gear meshes with four driven gears located on the axes of the pump. Each driven gear meshes with an auxiliary gear whose outer circumference is in contact with the periphery of the adjacent driven gear. Liquid is fed to one of the driven gears and is discharged from the adjacent driven 446 ntsI x . , Fig. 4 1 ,7 7 6g Fig. 5 Fig. 4. Planetary gear pump with liquid distribution by slide valves. Fig. 5. Gear pump with automatically controlled capacity. gear. The cavities formed by the drive, two driven, and auxiliary gears are connected by side passages in the cover with pockets between the drive and drive gears. The liquid thus passes in series through all the cavities and pockets of the pump insuring good mixing. A patented design of planetary gear pump is shown Fig.4 9. Four or six satellite gears and a sun gear are mounted in the casing of this pump. The pole is stationary and there is no crown wheel. The sun gear is driven by a shaft connected to the driver. The cylindrical collector cavity inside the sun gear is connected to the troughs of this gear by radial passages sealed from within by ball check valves, which are kept closed by a common ring shaped spring, or slide valves. During rotation of the sun gear the volume of liquid in the trough is compressed when both surfaces of a tooth of the satellite touch the circumference of the sun gear. Due to the decrease in geometric volume the excess liquid is forced out along the radial passage through the check valve or gate valve into the collector cavity of the sun gear and into the discharge chamber of the pump. Figure 5 shows the construction of a gear pump with outside gear meshing. The capacity of this pump is continuously variable 10. Drive 2 and driven 6 gears are installed in casing 1. Pistons 5 and 7 are tightly pressed to the drive gear. Piston 5 is pressed to the drive gear by spring 4 while the pumped liquid pressure presses on piston 7. The bloek, consisting of the drive gear and pistons, can be displaced paral- lel to the axis of the drive shaft. This movement varies the length of gear meshing. Increased system pressure reduces pump capacity by means of piston 7. Piston 5 is displaced when pressure decreases in- creasing the length of meshing and, thereby, pump capacity. Driver power remains constant. Stem 3 is used for manual control of the pump. Another variable capacity pump design has a casing consisting of two identically shaped halves with three gears mounted one above the other 11. The casing surrounds the circumference of the upper and lower gears. A chamber for letting down internal leakage is provided close to the middle gear whose axis is eccentrically located relative to the other two gears. Capacity is varied by changing the degree of ec- centricity of the middle gear reiative to the other two. A bolt connecting the two halves of the casing passes through the axis of the middle gear. The force exerted in tightening this bolt determines the side clearance between the gears and the housing. This bolt is also used to attach the level which is used to vary the posi- tion of the middle gear. There is another variable capacity three gear pump 12 which is of interest. The three gears are located in a row in machined cavities in the casing. The middle gear is installed on an eccentric bushing with large gaps relative tothe casing and can be moved from one gear to the other within the limits of mesh- ing. The suction and discharge openings of the pump are located between the side and middle gears. The pump capacity is zero when the regulating gear is in its central position since the delivery of the pumps formed by the middle and side gears are equal and opposed in direction, i.e., liquid flows from one gear to another passing around the middle gear. When the middle gear is moved in any direction its meshing is increased with one of the side gears and decreased with the other one. This either ncreases or decreases the pump throughput. A gear pump 13 is available which is designed to maintain constant composition of two component mixtures at the suction end and constant discharge flow. The pump consists of a driver, stand, mounting plate 447 ntsFig. 7 16 I 2 I Fig. 6 Fig. 8 Fig. 6. Distributor of a gear pump designed for pumping two component mix- ture of a preset composition. Fig. 7. Gear pump with a device to prevent compression of liquid trapped in gear teeth troughs. Fig. 8. Gear pump with automatic end clearance compensation. with two built-in gears and distributor with inlet valves, mixing chamber, and regulating mechanism in one of the intake passages. All these elements are connected by bolts. In the distributor (Fig. 6) one of the components of the mixture entering the pump is directed to mixing chamber 1 along directional passage 7 while the other flows along passage 6 through opening 3 and passage 2 of the control mechanism 4. The upperpart of the control mechanism is screwed into the distributor housing. Valve 6 can be partially or completely closed by turning lever 5 which is rigidly mounted on the extension of the control mechanism. This will vary the quantitative ratio of the components of the mixture in the mixing chamber. Liquid flows to the operating gears from the mixing chamber. The liquid is sealed in the trough of the gear teeth by the tight (without gaps) meshing of the teeth as well as the simultaneous meshing of two or several pairs of teeth. The volume of liquid confined in the trough between teeth decreases during gear rotation. Since liquid is relatively incompressible this causes a sharp increase in pressure causing liquid to be pressured through the end clearances to the suction line. Increased pressure results in high loads on the teeth and the support surface of the bearings. When liquid volume in the trough between teeth is decreased the pressure drops with evolution of vapors and air from the liquid. Pump capacity is reduced when vapors and air enter the suction chamber. Vapors and air are rapidly compressed when they enter the discharge resulting in shock waves against the teeth of the gears which often results in damage to the pump. Special unloading passages in the side covers of the casing, radial borings in the troughs, axial passages in the shaft etc., are provided to prevent trapping of liquid in the troughs of the teeth. A gear pump 14 has been developed with two narrow grooves cut in the side walls of the casing. One of these grooves extends to the opening under the bearing and serves as the supply route of lubricating liquid. The second groove is dead ended. It provides surge volume at the moment when liquid, which is confined in the troughs between teeth, is isolated from the suction and discharge chambers. The confined volume between the teeth is connected to both grooves at this moment reducing the degree of compression of the confined liquid. Another interesting gear pump design reduces the noise level during pump operation and the wear rate of the gears 15. An additional chamber is provided in the casing cover at the point of meshing of the gears which rotates together with the liquid volume confined between the teeth. This chamber acts as a dampener of pressure peaks when liquid volume decreases and prevents pres- sure from dropping too rapidly when the confined volume increases. By eliminating pressure surges at the point of gear meshing shock generation, and, consequently, tooth wear and noise level are reduced. 448 ntsJ 2 1 Fig. 9 A-A 2 Fig. 10 Fig. 11 Fig. 9. Mechanism for radial clearance compensation in a gear pump. Fig. 10. Gear pump with improved eavitational performance. Fig. 11. Gear pump with improved suction flooding of troughs of the gear (suction and discharge openings are shaded). Figure 7 shows the construction of a gear pump which eliminates the sharp increases or decreases in liquidpressure in the confined spaces between meshing teeth 16. Recesses 1 are provided in the side walls of the end discs. These recesses are contoured to follow meshing lines of the gears. The confined space between the teeth is connected, at the moment of meshing, through these recesses with adjacent spaces which are open and are connected to the suction or discharge chambers. Power losses occur during the operation of a gear pump which are caused by liquid leaking from the discharge chamber to the suction chamber through the radial clearance between the pump casing and the tips of the gear teeth and through the end clearance between the side walls of the pump casing and gear faces, as well as aong the line of contact of meshing teeth which are incorrectly shaped. Leakage is re- duced by attempts to minimize the radial clearance. The minimum radial clearance is determined primar- ily by the clearance in the bearings, their axial misalignment, and the eccentricity of the gears in the cas- ing. The magnitude of leakage is proportional to the cube of the clearance and depends on the liquid viscos- ity, the velocity of movement of the tips of the gear teeth relative to the plane of the pump casing and the pressure gradient. Liquid leakage is practically nil along the line of meshing contact if gears are fabri- cated in accordance with high quality standards. Liquid leakage through end clearances is several times larger than through radial clearances. This is due to resistance to liquid flow which is present in the radial clearances between the surface of the teeth and the casing during gear rotation, while gear rotation contributes to liquid leakage through the end clear- ances i