漢譯英
本設(shè)計(jì)通過(guò)對(duì)機(jī)械設(shè)計(jì)制造及其自動(dòng)化專業(yè)大學(xué)本科四年的所學(xué)知識(shí)進(jìn)行整合，完成一個(gè)特定功能、特殊要求的數(shù)控機(jī)床上下料機(jī)械手的設(shè)計(jì)，能夠比較好地體現(xiàn)機(jī)械設(shè)計(jì)制造及其自動(dòng)化專業(yè)畢業(yè)生的理論研究水平，實(shí)踐動(dòng)手能力以及專業(yè)精神和態(tài)度，具有較強(qiáng)的針對(duì)性和明確的實(shí)施目標(biāo)，能夠?qū)崿F(xiàn)理論和實(shí)踐的有機(jī)結(jié)合。
因?yàn)楸驹O(shè)計(jì)要求搬運(yùn)的加工工件的質(zhì)量達(dá)30KG，且長(zhǎng)度達(dá)500MM，同時(shí)考慮到數(shù)控機(jī)床布局的具體形式及對(duì)機(jī)械手的具體要求，考慮在滿足系統(tǒng)工藝要求的前提下，盡量簡(jiǎn)化結(jié)構(gòu)，以減小成本、提高可靠度。該機(jī)械手在工作中需要3種運(yùn)動(dòng),其中手臂的伸縮和立柱升降為兩個(gè)直線運(yùn)動(dòng),另一個(gè)為手臂的回轉(zhuǎn)運(yùn)動(dòng),綜合考慮，機(jī)械手自由度數(shù)目取為3，坐標(biāo)形式選擇圓柱坐標(biāo)形式，即一個(gè)轉(zhuǎn)動(dòng)自由度兩個(gè)移動(dòng)自由度，其特點(diǎn)是:結(jié)構(gòu)比較簡(jiǎn)單,手臂運(yùn)動(dòng)范圍大,且有較高的定位準(zhǔn)確度。
腰座回轉(zhuǎn)的驅(qū)動(dòng)形式要么是電機(jī)通過(guò)減速機(jī)構(gòu)來(lái)實(shí)現(xiàn)，要么是通過(guò)擺動(dòng)液壓缸或液壓馬達(dá)來(lái)實(shí)現(xiàn)，目前的趨勢(shì)是用前者。因?yàn)殡妱?dòng)方式控制的精度能夠很高，而且結(jié)構(gòu)緊湊，不用設(shè)計(jì)另外的液壓系統(tǒng)及其輔助元件?？紤]到腰座是機(jī)器人的第一個(gè)回轉(zhuǎn)關(guān)節(jié)，對(duì)機(jī)械手的最終精度影響大，故采用電機(jī)驅(qū)動(dòng)來(lái)實(shí)現(xiàn)腰部的回轉(zhuǎn)運(yùn)動(dòng)。一般電機(jī)都不能直接驅(qū)動(dòng)，考慮到轉(zhuǎn)速以及扭矩的具體要求，采用大傳動(dòng)比的齒輪傳動(dòng)系統(tǒng)進(jìn)行減速和扭矩的放大。因?yàn)辇X輪傳動(dòng)存在著齒側(cè)間隙，影響傳動(dòng)精度，故采用一級(jí)齒輪傳動(dòng)，采用大的傳動(dòng)比（大于100），同時(shí)為了減小機(jī)械手的整體結(jié)構(gòu)，齒輪采用高強(qiáng)度、高硬度的材料，高精度加工制造，盡量減小因齒輪傳動(dòng)造成的誤差。
機(jī)械手的垂直手臂（大臂）升降和水平手臂（小臂）的伸縮運(yùn)動(dòng)都為直線運(yùn)動(dòng)。直線運(yùn)動(dòng)的實(shí)現(xiàn)一般是氣動(dòng)傳動(dòng)，液壓傳動(dòng)以及電動(dòng)機(jī)驅(qū)動(dòng)滾珠絲杠來(lái)實(shí)現(xiàn)。考慮到搬運(yùn)工件的重量較大，考慮加工工件的質(zhì)量達(dá)30KG，屬中型重量，同時(shí)考慮到機(jī)械手的動(dòng)態(tài)性能及運(yùn)動(dòng)的穩(wěn)定性，安全性，對(duì)手臂的剛度有較高的要求。綜合考慮，兩手臂的驅(qū)動(dòng)均選擇液壓驅(qū)動(dòng)方式，通過(guò)液壓缸的直接驅(qū)動(dòng)，液壓缸既是驅(qū)動(dòng)元件，又是執(zhí)行運(yùn)動(dòng)件，不用再設(shè)計(jì)另外的執(zhí)行件了；而且液壓缸實(shí)現(xiàn)直線運(yùn)動(dòng)，控制簡(jiǎn)單，易于實(shí)現(xiàn)計(jì)算機(jī)的控制。
因?yàn)橐簤合到y(tǒng)能提供很大的驅(qū)動(dòng)力，因此在驅(qū)動(dòng)力和結(jié)構(gòu)的強(qiáng)度都是比較容易實(shí)現(xiàn)的，關(guān)鍵是機(jī)械手運(yùn)動(dòng)的穩(wěn)定性和剛度的滿足。因此手臂液壓缸的設(shè)計(jì)原則是缸的直徑取得大一點(diǎn)（在整體結(jié)構(gòu)允許的情況下），再進(jìn)行強(qiáng)度的較核。
同時(shí)，因?yàn)榭刂坪途唧w工作的要求，機(jī)械手的手臂的結(jié)構(gòu)不能太大，若僅僅通過(guò)增大液壓缸的缸徑來(lái)增大剛度，是不能滿足系統(tǒng)剛度要求的。因此，在設(shè)計(jì)時(shí)另外增設(shè)了導(dǎo)桿機(jī)構(gòu)，小臂增設(shè)了兩個(gè)導(dǎo)桿，與活塞桿一起構(gòu)成等邊三角形的截面形式，盡量增加其剛度；大臂增設(shè)了四個(gè)導(dǎo)桿，成正四邊形布置，為減小質(zhì)量，各個(gè)導(dǎo)桿均采用空心結(jié)構(gòu)。通過(guò)增設(shè)導(dǎo)桿，能顯著提高機(jī)械手的運(yùn)動(dòng)剛度和穩(wěn)定性，比較好的解決了結(jié)構(gòu)、穩(wěn)定性的問(wèn)題。
通過(guò)對(duì)數(shù)控機(jī)床上下料作業(yè)的具體分析，考慮數(shù)控機(jī)床加工的具體形式及對(duì)機(jī)械手上下料作業(yè)時(shí)的具體要求，在滿足系統(tǒng)工藝要求的前提下提高安全和可靠性，為使機(jī)械手的結(jié)構(gòu)盡量簡(jiǎn)單，降低控制的難度，本設(shè)計(jì)手腕不增加自由度，實(shí)踐證明這是完全能滿足作業(yè)要求的，3個(gè)自由度來(lái)實(shí)現(xiàn)機(jī)床的上下料完全足夠。
本設(shè)計(jì)采用連桿杠桿式的手爪。驅(qū)動(dòng)活塞往復(fù)移動(dòng)，通過(guò)活塞桿端部齒條，中間齒條及扇形齒條使手指張開(kāi)或閉合。手指的最小開(kāi)度由加工工件的直徑來(lái)調(diào)定。本設(shè)計(jì)按照工件的直徑為50mm來(lái)設(shè)計(jì)。
因?yàn)檫x用了液壓缸作為機(jī)械手的水平手臂和垂直手臂，由于液壓缸實(shí)現(xiàn)直接驅(qū)動(dòng)，它既是關(guān)節(jié)機(jī)構(gòu)，又是動(dòng)力元件。故不需要中間傳動(dòng)機(jī)構(gòu)，這既簡(jiǎn)化了結(jié)構(gòu)，同時(shí)又提高了精度。而機(jī)械手腰部的回轉(zhuǎn)運(yùn)動(dòng)采用步進(jìn)電機(jī)驅(qū)動(dòng)，必須采用傳動(dòng)機(jī)構(gòu)來(lái)減速和增大扭矩。經(jīng)分析比較，選擇圓柱齒輪傳動(dòng)，為了保證比較高的精度，盡量減小因齒輪傳動(dòng)造成的誤差；同時(shí)大大增大扭矩，同時(shí)較大的降低電機(jī)轉(zhuǎn)速，以使機(jī)械手的運(yùn)動(dòng)平穩(wěn)，動(dòng)態(tài)性能好。這里只采用一級(jí)齒輪傳動(dòng)，采用大的傳動(dòng)比（大于100），齒輪采用高強(qiáng)度、高硬度的材料，高精度加工制造。
在分析了具體工作要求后，綜合考慮各個(gè)因素。機(jī)械手腰部的旋轉(zhuǎn)運(yùn)動(dòng)需要一定的定位控制精度，故采用步進(jìn)電機(jī)驅(qū)動(dòng)來(lái)實(shí)現(xiàn)；因?yàn)椴捎靡簤簣?zhí)行缸來(lái)做水平手臂和垂直手臂，故大小臂均采用液壓驅(qū)動(dòng)；同時(shí)考慮隨著機(jī)床加工的工件的不同，水平手臂伸出長(zhǎng)度是不同的。因此，要求水平手臂具有伺服定位能力，故采用電液伺服液壓缸進(jìn)行驅(qū)動(dòng)。
而手爪的張開(kāi)和夾緊通過(guò)液壓柱塞缸活塞與中間齒輪和扇形齒輪配合來(lái)實(shí)現(xiàn)，即手爪在柱塞缸推力作用下通過(guò)活塞桿端部齒條、中間齒輪及扇形齒輪使手指張開(kāi)和閉合。
因?yàn)楸驹O(shè)計(jì)機(jī)械手采用圓柱坐標(biāo)型的結(jié)構(gòu)，而且在手臂的結(jié)構(gòu)設(shè)計(jì)以及整個(gè)機(jī)械手的設(shè)計(jì)和布局中都重點(diǎn)考慮了機(jī)械手手臂的平衡問(wèn)題，通過(guò)合理布局，優(yōu)化設(shè)計(jì)結(jié)構(gòu)，使得手臂本身盡可能達(dá)到平衡。若實(shí)際工作中平衡結(jié)果不滿足，則設(shè)置彈簧平衡機(jī)構(gòu)進(jìn)行平衡。
Through the design and automation machinery design and manufacture of professional four-year college to integrate the knowledge to complete a specific function, the special requirements of the NC machine tool manipulator up and down the design of materials that can better reflect the design and manufacture of machinery and automation Theoretical Study on the professional level of graduates, the practice of practical ability and professional spirit and attitude, a strong and clear implementation of targeted objectives, theory and practice to realize the organic integration.
Because the design requirements for handling the processing of the quality of the workpiece 30KG, and length of 500MM, CNC machine tools at the same time taking into account the exact form and layout of the specific requirements of manipulator, considering the technological requirements to meet the system under the premise of the structure as simple as possible in order to reduce costs and improve reliability. The robot in the three kinds of work need to exercise, in which the telescopic arm and the post take-off and landing for the two linear motion, and the other for the rotating arm movements, taken together, taking the number of degrees of freedom manipulator 3, the form of choice of coordinates the form of cylindrical coordinates, that is, rotational degrees of freedom of a two degree of freedom movement, which is characterized by: a relatively simple structure, wide range of arm movement and positioning of high accuracy.
Driver seat lumbar rotary motor through the form of either body to slow down the achievement, or by oscillating hydraulic cylinders or hydraulic motors to achieve, the current trend is to use the former. Because the electric control to a very high accuracy and compact structure, not the design of other hydraulic system and its auxiliary components. Taking into account the back seat is the first robot rotary joints, on the ultimate precision manipulator impact, so the use of motor drives to achieve the waist of the Rotary movement. General Motors can not be directly driven, speed and torque, taking into account the specific requirements of large transmission ratio of the gear drive system for speed and torque amplification. Because there is a gear tooth gap, the impact of driving accuracy, so the use of a gear drive, using a large transmission ratio (greater than 100), at the same time in order to reduce the overall structure of manipulator, gear using high-strength, high hardness of the material, high-precision manufacturing to minimize gear due to errors.
Vertical manipulator arm (the arm) and levels of arm movements (arm) for movement of the telescopic linear motion. The realization of the general linear motion drive is pneumatic, hydraulic and motor-driven ball screw drive to achieve. Porters, taking into account the weight of larger pieces, considering the quality of the workpiece 30KG, to be medium weight, taking into account the robot dynamic performance and sporting the stability, security, on the arm of a higher stiffness. Considered, the two arms of the driver choose to hydraulic drive through a direct drive hydraulic cylinder, hydraulic cylinder is a driver component, but also the implementation of moving parts, no need to design the implementation of other parts of the; and hydraulic cylinders to achieve a straight line movement, control is simple, easy to implement computer control.
Because the hydraulic system can provide a great driving force, and therefore the driving force and structure of the intensity are relatively easy to achieve, the key is the stability of robot movement and rigidity of the meet. Therefore the design of hydraulic cylinder arm principle is the cylinder made larger in diameter (in the overall structure of permitting), further than the nuclear strength.
At the same time, because the control and the specific work requirements of the robot arm structure is not too great, if only by increasing the cylinder bore to increase the stiffness, the stiffness can not meet the system requirements. Therefore, in the design of the guide the creation of additional agencies, the addition of the two arm guide rod, and piston rod together constitute an equilateral triangle cross-section of the form, as far as possible to increase its stiffness; additional four large arm guide, arranged into a square , in order to reduce the quality of each guide are hollow structure. Through the addition of lead shot, can significantly increase the stiffness of robot movement and stability, a better solution of the structure, stability problems.
CNC machine tools up and down through the specific analysis of materials, CNC machining to consider the specific form and cutting the hands of the mechanical operation of the specific requirements of technology in meeting the requirements of the system to improve safety and reliability, in order for the structure of manipulator as simple as possible to reduce the difficulty of control, the design does not increase the degree of freedom wrist, in practice show that it is fully able to meet operational requirements, and three degrees of freedom to the whole machine is expected to achieve fully adequate.
The design of the gripper rod leveraged. Reciprocating piston-driven movement, through the rod tip rack, the middle rack and the fan-shaped rack so that the fingers open or closed. Fingers from the smallest opening to the diameter of workpiece is set. The design in accordance with the workpiece to a diameter of 50mm design.
Because the hydraulic cylinder was chosen as the level of robot arm and vertical arm, as a result of direct drive hydraulic cylinder, it is a joint body, but also dynamic components. It does not need the middle of transmission, which not only simplified the structure, while at the same time improve the precision. The waist of the rotary robot movement using stepper motor driven drive mechanism must be used to increase speed and torque. Analysis of comparison, the choice of cylindrical gear drive, in order to ensure higher accuracy, due to gear to minimize errors; the same time, greatly increased torque, while a larger decrease in motor speed, so that smooth movement of the manipulator, the dynamic performance好. Here only one gear, the transmission ratio of large (greater than 100), gear for high strength, high hardness materials, high-precision manufacturing.
After analyzing the specific job requirements, the various factors considered. Manipulator rotation waist take some control over positioning accuracy, so the use of stepper motor drive to achieve; because of the hydraulic cylinder to do the level of implementation of the arms and the vertical arm, the arms are the size of the hydraulic drive; taking as machining the workpiece is different from the level of extending the length of the arm is different. Therefore, the requirements with the servo arm positioning capability, it is carried out using electro-hydraulic servo-driven hydraulic cylinder.
And hand through the open and clamping hydraulic cylinder piston and the intermediate plunger, and fan gear with the gear to achieve, namely, hand thrust in the role of plunger-cylinder piston rod end through the rack, the middle gear and fan gear so fingers open and closed.
Because of the design using cylindrical coordinate manipulator-type structure, but also in the structural design of the arm and the robot design and layout of the key points of consideration are the manipulator arm of the balance, through the rational distribution and optimize the design of the structure, making the arm itself, as far as possible to achieve a balance . If the results of actual work are not satisfied with the balance, the body set up to balance the spring balance.
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