CNC machine loading and unloading manipulator

Abstract: The mechanical design, manufacturing and automation professional courses of study, summed up the knowledge learned in college four years, the industrial robot mechanical structure and function of various parts of exposition and analysis, and practical application in the design of a types of cylindrical form of CNC machine loading and unloading robot. focusing on the robot gripper, wrist, arm, waist and seat and other parts of the mechanical structure and the robot control system (transmission, drive system, a detailed design. while its control system and the hydraulic system analysis and design calculations. based on PLC on the robot control system is further detailed design, through the mechanical hand operation process and control requirements analysis, design of the control system hardware circuit, while the preparation of the manipulator control program. designed to meet the expected goals.

Keywords:: robot, PLC, hydraulic servo positioning, electro-hydraulic system

CONTENTS

Chapter 1 Introduction .............................................. ............... 1

1.1 The research background. 1

1.2 Design objectives. 1

1.3 Development Status and trends. 1

Chapter 2 Design of the various components of robot 3.

2.1 The overall design of the robot 3.

2.1.1 The overall structure of the type of robot 3.

2.1.2 Specific design. 4

2.2 Structure of robot gripper design. 4

2.2.1 Design requirements. 4

2.2.2 drive 5.

2.2.3 Typical Structure 5.

2.2.4 Specific design. 6

2.3 Structure of robot wrist design. 7

2.3.1 wrist structural design requirements. 7

2.3.2 Specific design. 7

2.4 The design of the robot arm structure. 8

2.4.1 arm structure design requirements. 8

2.4.2 Specific design. 8

2.5 Mechanical Hand Yao Block Structure. 9

2.5.1 Block structure of the design requirements of the waist. 9

2.5.2 Specific design. 9

2.6 Manipulator design of the mechanical transmission 10.

2.6.1 transmission design should pay attention to. 10

2.6.2 common forms of transmission 10.

2.6.3 Specific design. 11

2.7 Design of robot drive system. 12

2.7.1 common drive system and its features. 12

2.7.2 Specific design. 12

2.8 the balance of the robot arm mechanism design. 12

2.8.1 balance mechanism in the form. 12

2.8.2 Specific design. 13

Chapter 3 Theoretical analysis and design calculations. 14

3.1 Motor Selection of the parameters calculated. 14

3.1.1 Calculation of the parameters 14.

3.1.2 Motor model choice. 16

3.2 Calculation of hydraulic system design. 18

3.2.1 determine the basic scheme of hydraulic system. 18

3.2.2 proposed control loop hydraulic actuator movement. 19

3.2.3 Design of the hydraulic source system. 19

3.2.4 Drawing Hydraulic system diagram. 20

3.2.5 identify the main parameters of the hydraulic system. 21

3.2.6 Calculation and selection of hydraulic components. 26

Chapter 4, robot control system. 28

4.1 System hardware design. 28

4.1.1 control panel layout. 28

4.1.2 process and control requirements. 28

Processes 4.1.3. 29

4.1.4 Selection of the controller. 30

4.1.5 Principles of control systems analysis. 31

4.1.6 PLC external wiring design. 31

4.1.7 I / O address assignment. 32

4.2 system software design. 33

4.2.1 Control of the main program flow chart. 33

4.2.2 Design of control procedures. 34

Conclusion. 51

Acknowledgements ................................................. ............... 52

References ................................................ .......... 53

Chapter Introduction

1.1 The research background

Since the overall development of industrial automation and scientific technology continues to improve efficiency of work is imminent. Simple manual labor to meet the requirements of industrial automation can not, therefore, must use advanced equipment, production automation machinery to replace human labor, to meet the industrial automation needs. manipulator which is important in the process of its development one of the products, which not only improve the efficiency of labor productivity, but also replace humans to complete high-intensity, dangerous, repetitive boring work, reducing human labor intensity, can be said to serve two purposes. in the machinery industry, the mechanical hand more and more widely applied, it can be used for parts assembly, workpiece handling, loading and unloading, particularly in the automation of CNC machine tools, machine tool use is more common. Currently, the robot has become FMS flexible manufacturing systems and flexible manufacturing cell in an important part of FMC. the machine tools and robots together to form a flexible manufacturing system or a flexible manufacturing cell, can save a large piece delivery devices, compact, and adaptable. but China's industrial robot technology and its application level and there is a certain distance than abroad, application size and low level of industrialization, research and development of robot directly affect China's machinery industry, raising the level of automation, from the economy, technology the considerations are very necessary. Therefore, research and design of mechanical hand is important.

1.2 designed to

At present, most of the factory production line CNC machine tools still done manually loading and unloading the workpiece, its labor intensity, low productivity, but also has some risk, has failed to meet the development trend of production automation. In order to improve efficiency, reduce costs , and production lines to become flexible manufacturing system to adapt to modern machinery industry automation requirements of specific production process, combined with the actual machine tool structure, the use of robot technology to design with a platform cutting robots instead of manual work to improve labor productivity. The main manipulator combination of the final forming and CNC machine tool production line, and process automation and unmanned.

1.3 Development Status and Trends

Currently, various domestic and international robotic manipulator and study to become a hot research, the general trend of the current situation and are as follows:

One. Mechanical structure to the modular and reconfigurable development.

II. Industrial robot control system to an open PC-based controller direction, to facilitate standardization, network, raise the degree of device integration, compact, and modular structure, greatly improving the system reliability, ease, and maintenance convenient.

III. Robot sensors increasingly important role, in addition to the traditional position, velocity, acceleration and other sensors, but also the introduction of visual, auditory, tactile sensor contacts, make it to the intelligent direction.

IV. Articulated, side spray, top spray, spray gantry robot product standardization, universal, modular, serial design, flexible profiling spraying robot development, institutional development of flexible composite profile, profile servo axis trajectory planning studies, control systems development,

Five. Welding, handling, assembly, cutting and other operations of the industrial robot product standardization, universal, modular, serial studies, and off-line teaching programming and system dynamic simulation.

Overall, roughly two directions: One is the intelligent robot, multi-sensor, multi-controllers, advanced control algorithms, the complex electrical and mechanical control system, the other is associated with the production and processing, cost-effective in meet the work requirements, based on the pursuit of systematic economic, simple, reliable, and extensive use of industrial controllers, market-oriented, modular components.

Chapter II the design of robot parts

2.1 The overall design of the manipulator

2.1.1 The overall structure of the type of robot

The structure of industrial robots, there are four: the structure Cartesian coordinates, cylindrical coordinates of the structure, spherical structure and the joint structure coordinates. The structure and its corresponding features, are described as follows:

1. Cartesian coordinate manipulator characteristics

Cartesian space motion of the manipulator is to use three mutually perpendicular linear motion to achieve, as shown in Figure 2-1.a. Since linear motion is easy to implement closed loop position control, therefore, high precision location of motion, but this type of robot movement space is relatively small, such as to achieve a larger space of movement, requires the robot size is large enough. Cartesian coordinate manipulator work space is a space rectangular, mainly for assembly operations and handling operations. Cartesian coordinate manipulator has cantilevered , gantry, crane-style Three structure.

2. Cylindrical coordinate manipulator characteristics

Cylindrical coordinate space motion of the manipulator is to use a turning motion and two linear motion to achieve, as shown in Figure 2-1.b. Their work space is a cylindrical space. This structure is relatively simple robot, the accuracy is relatively high, commonly used in transportation operations.

3. Manipulator structural characteristics of the spherical coordinate

Spherical coordinate space motion of the manipulator consists of two rotary movement and a linear motion to achieve, as shown in Figure 2-1.c. Its work space is a spherical space. The robot structure is simple, low cost, but the accuracy not very high, mainly used in transportation operations.

4. Characteristics of Articulated Manipulator

Articulated robot spatial motion is achieved by the three rotary motion, as shown in Figure 2-1.d. Manipulator relative to body size, a larger space for their work, action and flexible, compact, small footprint. Such robots in industry very wide application, such as welding, painting, handling, assembly and other operations. Articulated robot is divided into horizontal and vertical joints articulated two kinds.

2.1.2 the specific use of the program

Shown in Figure 2-2 Layout robot simulation work, according to the needs of the actual operation, the robot needs three kinds of work movement, stretching and column in which the arm movements to linear motion, and the other for the rotary arm movement, so its number of 3 degrees of freedom, considering, should choose a cylindrical coordinate manipulator, and its simple structure, is relatively large, and there is a high precision, to meet the design requirements.

2.2 The structural design of the robot gripper

2.2.1 Design requirements

Gripper is used for operation and operation of the device, its many types, according to the different ways of operation and work is divided into transport use, processing, measurement and so on. Handling a variety of gripping with the gripper device is used to crawl or adsorption is handling objects, processing gripper is of a gun, welding torch, grinding wheel, milling and other processing tools, mechanical hand attached device, used for the appropriate processing operations, the measurement probe gripper is equipped with Additional devices or sensors, used for measurement and inspection operations.

Robot gripper design has the following requirements:

1, robotic manipulator gripper is based on operational requirements to design. Both the gripper in accordance with its design applications, to meet the operational requirements of the premise, the robot gripper also require small size, light weight, compact structure.

2, robot gripper with the specific nature of the universal nature is contradictory. Universal gripper is complex in structure, or even difficult to achieve, practical application from the industry should focus on developing a variety of dedicated, highly efficient robot gripper, coupled with the rapid replacement of devices in order to achieve a variety of job functions manipulator, and not advocate the use of a universal gripper to complete a variety of operations to take into account the economic benefits of the design.

3, the versatility of the robot gripper. Versatility is limited gripper, suitable for different robot, which requires the end of the actuator to have a standard mechanical interface (such as flange, the end of the actuator to achieve standardization.

4, robot gripper to facilitate the installation and maintenance, easy to implement computer control.

2.2.2 drive

General industrial robot gripper, mostly for two-finger gripper. According to the movements of the fingers can be classified into the type of transformation and movement, by way of clamping points, outside the folder and inside there are two kinds of support.

Robot gripper (gripper drive in three main ways:

1. Pneumatic drive

The drive system is used to control the solenoid valve direction of movement of the gripper, with the air control valve to adjust its velocity. Pneumatic drive system because of lower prices, so the pneumatic gripper is more common in industrial application. Also, the gas the compressibility, the pneumatic gripper crawling movement has some flexibility, it is crawling action is needed.

2. Electric drive

Application of electric drive gripper is also more widely. This gripper, generally use the DC servo motor or stepper motor, and need to get enough gear drives and torque. Electric drive can be achieved gripper force and position control . However, this drive can not be used under the conditions of explosion-proof requirements, because the motor may produce sparks and heat.

3. Hydraulic drive

Hydraulic drive is controlled by hydraulic system, transmission stiffness, continuous position control can be achieved.

2.2.3 Typical Structure

The typical structure of the robot gripper has the following five:

1. Wedge gripper lever

Use of wedges and levers to achieve the gripper's loose, open, to achieve capture the workpiece.

2. Chute paw

When the piston moves forward, the slide through the gripper pins to promote combined to produce the clamping action and the clamping force, when the piston backward movement, the gripper release. This gripper opening and closing of a larger trip to meet the grasping take the size of different objects.

3. Gripper rod lever

The thrust of the piston, the connecting rod and lever to generate clamping gripper (relaxation exercises, the force amplification of the lever, which may have a greater gripper clamping force. Usually used in conjunction with the spring.

4. Gripper rack and pinion

Through the piston driven rack, rack drive gear rotation, produce and release the clamping gripper action.

5. Parallel gripper lever

With parallelogram mechanism, so no guide can guarantee a two finger gripper parallel to the movement, and movement than with a parallel gripper rail friction is much smaller.

2.2.4 Specific Design

Combined with specific work, the design uses lever-type gripper rod. Drive the piston moves back and forth through the rod end, rack, rack and fan-shaped rack to the middle fingers open or closed. Fingers by the smallest opening workpiece diameter to be adjusted. The design of the workpiece diameter is 50mm according to design. gripper specific structure shown in Figure 2-3:

2.3 Structure of robot wrist design

Robot wrist is the most robotic manipulator end connected with the gripper, manipulator arm with it, so that the gripper movement in space to complete the required job action.

2.3.1 Structural design requirements for the wrist

1, as installed in the robot wrist end, thus requiring the wrist should be compact and lightweight design, compact structure.

2, according to operational requirements, the design freedom of the robot wrist. In general, the more the number of degrees of freedom, the higher the flexibility of the wrist, right, the stronger ability to adapt to the job. However, the increase in degrees of freedom, will bring the wrist Department structure is more complex and more difficult to control, the cost will increase accordingly. Therefore, the number of degrees of freedom wrist, should be determined based on the actual operational requirements.

3, for the realization of universal wrist, requiring a standard flange, so that the robot gripper and different connecting.

4, the work force to ensure the delivery and continuity of movement, the wrist structure have sufficient strength and stiffness.

5, to have a reliable transmission gap adjusting mechanism to reduce the air back to the gap and improve the transmission accuracy.

6, the wrist joint axis of rotation of the position switch to the limited and set the hard limit to prevent overrun caused by mechanical damage.

2.3.2 Specific Design

Through the CNC machine loading and unloading operations of the specific analysis, consider the CNC machining of specific forms and on the mechanical hand cutting operations to the specific requirements to meet the system process requirements under the premise of improving the safety and reliability, for the manipulator structure as simple as possible reduce the difficulty of control, the wrist does not increase the design freedom proved to be fully able to meet operational requirements, and 3 degrees of freedom to realize fully adequate loading and unloading the machine. specific wrist (arm gripper coupling beam structure shown in Figure 2-4.

2.4 The design of the robot arm structure

2.4.1 Structural design requirements for the arm

Robot arm at work, to bear a certain load, and the movement itself has a certain speed, so the design of the robot arm to follow the following design requirements:

1, the shape and size of working space and the length of the robot arm, the arm rotating joint is closely related to the scope, so the arm size design should be reasonable and generally to meet their work space.

2, in order to improve mechanical hand speed and control accuracy of the motion should be Baozheng mechanical hand �ֱ� adequate strength and stiffness of the conditions, as far as structure, materials Shefa arm to reduce weight.

3, the robot arm as far as possible so that the joint axes parallel to each other, mutually perpendicular axes intersect at one point as far as possible, this could make the robot inverse kinematics is simplified, is conducive to robot control.

4, manipulator each joint bearing clearance should be as small as possible to reduce the gap caused by the mechanical motion error.

5, the robot arm movement to improve the response speed, reducing the electrical load, the robot arm relative to the rotary joint as far as possible in terms of weight balance.

2.4.2 Specific Design

As the robot arm motion to linear motion, and taking into account the weight of large pieces of porters (mass up to 30KG, and the robot dynamic performance and stability of movement, security, and high stiffness requirements, choosing the hydraulic drive. By hydraulic direct drive cylinder, hydraulic cylinder is both driven elements, but also the implementation of moving parts, so no need to perform additional design pieces, and the hydraulic cylinder to achieve linear motion control is easy to implement computer control.

Because the hydraulic system can provide a great driving force, driving force and therefore the strength of the structure are relatively easy to implement, the key lies in the stability of robot motion and stiffness design. So the design principles of the arm cylinder is made much the diameter of the hydraulic cylinder point (in the overall structure of the permission, then the strength of more nuclear.

Also, because the control and specific job requirements, the structure of the robot arm can not be too, if only by increasing the diameter of the hydraulic cylinder to increase the stiffness, the stiffness can not meet the system requirements. Therefore, the addition of another in the design guide bar linkage, two additional guide rod arm, and the piston rod together constitute the section of the form of an equilateral triangle, as far as possible to increase its stiffness, the addition of four arm guide rod, as is quadrilateral arrangement for reducing the quality of each guide rod are used hollow structure. through the addition of guide, can significantly improve the movement of the robot stiffness and stability, a better solution to the structure, stability problems.

2.5 Structure of robot design seat back

2.5.1 Block structure of the design requirements of the waist

Block waist robot is turning the manipulator base. It is the first rotary robot joint, to bear the full weight of the manipulator. So back seat in the design of the robot structure, the following design requirements:

1, the back seat to bear the robot all the weight and load, so the robot back seat of the structure to have enough strength and stiffness to ensure that its carrying capacity, and the back seat is a manipulator of the first rotary joint, its robot the greatest impact at the end of motion accuracy, therefore, pay special attention in the design of shaft and drive chain waist accuracy and rigidity.

2, waist structure should be easy to install and adjust. To have a reliable positioning surface and the adjustment of the body. And the back seat big enough to be installed in the base surface to ensure that the robot is installed at work, the overall stability.

3, the waist of the rotary motion to have the appropriate device drivers, which include the drive and reducer. Drive normally with the speed and position sensors, and brake.

4, in order to reduce the manipulator inertia of moving parts to improve the control precision, requiring rotary motion in part by the relatively small proportion of aluminum alloy material, without exercise is to use cast iron or steel base material.

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2.5.2 Specific Design

Block rotation of the drive back, there are two main forms, one motor through the reduction mechanism to achieve, and second, through the swinging hydraulic cylinders or hydraulic motors to achieve. Taking into account the back seat is the first rotary robot joint, on the ultimate accuracy of the robot large, so the use of motor drive to achieve the waist of the rotational movement. because the electrically-controlled, high precision, compact design without additional auxiliary hydraulic system and its components. can not directly drive the motor, taking into account the specific speed and torque requirements, so the use of large transmission gear ratio and torque gear transmission system for the amplification. Because there is gear backlash, the accuracy of transmission, the only use of a gear drive, using a large transmission ratio (greater than 100, At the same time to reduce the transmission error, the gear with high strength, high hardness materials, precision manufacturing. back seat concrete structure shown in Figure 2-5:

2.6 Manipulator design of mechanical transmission

2.6.1 transmission design should pay attention to the problem

As a direct impact on the mechanical transmission parts hand precision, stability and rapid response capability, therefore, in the design of robot drive mechanism to pay attention to the following questions:

1, the manipulator drive mechanism should strive for compact, light weight, small size, to increase the velocity of the robot and control accuracy. And in the transmission chain and the use of gap adjustment vice sport organizations to reduce the back caused by the reverse air motion error.

2, the system of moving parts to minimize the static friction, and friction is a small positive slope as possible, to eliminate the creeping phenomenon, increase system life.

3, try to shorten the drive chain and improve the transmission and bearing stiffness.

4, the selection of the best gear ratio to achieve greater system resolution and reduce the equivalent to the output shaft of the actuator inertia equivalent to maximize the acceleration.

5, the appropriate damping ratio. Damping ratio increases, the maximum amplitude of the vibration components smaller, faster decay. But large systematic errors will increase the damping, the accuracy decreases. It should be taken to the appropriate damping ratio.

2.6.2 common form of transmission

The mechanical drive mechanism used mainly screw drive, gear drive, chain drive, belt drive and so on.

1. Screw Drive

It is mainly used to transform the rotary motion to linear motion or linear motion to rotary motion conversion. Has delivered energy-based, such as screw press, jack, etc., have to deliver sports-oriented, such as machine tool table into to the screw.

2. Gear

Commonly used in robot gear transmission with cylindrical gears, bevel gear, harmonic gears, cycloid and the worm gear and so on.

Gear parts are torque, speed and direction of the converter, gear reducer for the servo system is a torque converter. Gear drive, the form and the transmission gear ratio to be the best match, should meet the drive components and displacement between the load and torque, rotational speed of the matching requirements, the input motor for high speed, low torque, while the output was low speed, high torque, and the system should have sufficient rigidity. Meanwhile, to ensure the same drive power, its acceleration maximum, also called the moment of inertia small as possible. To make the system stable, no transmission dead zone, to maximize the use of gear backlash, high precision gears, and by adjusting the tooth gap approach to eliminate or reduce the meshing gap, thereby improving transmission accuracy and stability of the system and reduce costs.

3. Chain drive

Chain drive in the robot used for transmission on the wrist, in order to reduce the weight of the robot at the end, usually the wrist drive motor mounted on the back-end or boom arm joints. As the motor drive from the wrist to be far away, so it precision sleeve roller chain drive.

4. Belt drive

Belt drive is a combination of general advantages of belt drive and chain drive of a new transmission. To ensure that no sliding zone and the synchronization with the rotation drive pulley in the belt of the face and the peripheral system are used on both inelastic deformation after load high-strength material engagement teeth were driving through the meshing teeth. It features accurate transmission ratio, high transmission efficiency (up to 98%, energy-saving effect, absorbing vibration, low noise, no lubrication, smooth transmission, can high-speed transmission (up to 40m / s, the transmission ratio of up to 10, compact, and easy to maintain, so they use a lot of the robot.

2.6.3 Specific Design

In which the use of the hydraulic cylinder as the robot arm, it is both joint structure, but also a power unit, so no intermediate transmission, not only simplifies the structure, but also improves accuracy. While the lumbar seat rotary motor driven by step, and components can not be used as direct drive motor, so as to achieve greater torque, the analysis and comparison, select the cylindrical gear. In order to ensure higher accuracy, minimize errors caused by gear drive, while significantly increasing torque to larger decrease motor speed, so that smooth movement of the robot, the dynamic performance. here only with a gear drive, using a large transmission ratio (greater than 100, the gear with high strength, high hardness materials, precision manufacturing.

2.7 Robot Drive System

2.7.1 common drive system and its characteristics

Industrial drive systems commonly used by the power source into the hydraulic, pneumatic and electric three categories. According to the basic needs of these three types can be combined into a hybrid drive system. These three main features of the basic drive system is as follows.

1. Hydraulic drive system

With great power, force (or torque inertia ratio with large, fast response, easy to implement direct-drive, high accuracy. Suitable for the load capacity, large and in the fire and explosion used to work in an environment of the robot.

2. Pneumatic drive system

High speed, simple structure, easy maintenance, low prices. Suitable for medium and small-load robot used. However, due to difficult to achieve servo control, multi-robot control for the program.

3. Electric drive system

Easy to use, low noise, flexible control and so on. Such drive system does not require energy conversion, but most of the motor to be installed behind the precision of the transmission mechanism.

2.7.2 Specific Design

In the analysis of the specific job requirements, the comprehensive consideration of various factors, waist rotation manipulator position control requires a certain precision, so a stepper motor to achieve. The arm with hydraulic cylinders, hydraulic drives it. As the workpiece machining different, arms stretched out in length, with the servo arm positioning capability required, it is driven by servo hydraulic cylinders. The gripper's opening and clamping piston by hydraulic piston and sector gear and intermediate gear to achieve with that the gripper cylinder thrust in the role of the plunger rod end through the rack, gear and sector gear to the middle fingers open and closed.

2.8 the balance of the robot arm mechanism design

Rectangular type, type and spherical coordinates cylindrical coordinate type robot can be rationally optimized design structure, making the arm itself may be in balance. Joint robot arm balancing device generally needs to reduce the load on the drive, while reducing start-up time.

2.8.1 balance mechanism in the form of

1. Counterweight balancing mechanism

The balance of simple structure and good balance effect, easy to adjust, reliable, but increased the inertia of the robot arm and the joint axis loads. Manipulator arm is generally unbalanced moment the case of small organizations using this balance.

2. Spring balance mechanism

Spring balance institutions, institutional simple, low cost, reliable, good balance effect, easy maintenance, so widely used.

3. Piston push rod balancing mechanism

Balance piston system is divided into two, one hydraulic balance system, the second is air balance system. Counterweight balance system in which the hydraulic, small size, a certain damping effect, and air balance system, has a good damping effect but the volume is relatively large. Reciprocating balance need to be equipped with special hydraulic or pneumatic devices, the system complex, high cost, design, installation and debugging more difficult, but good balance effect. for the weight balance, spring balance can not meet work requirements of the occasion.

2.8.2 Specific Design

Because of the mechanical hand is made of cylindrical coordinates, type of structure, and the arm of the structural design and the whole robot design and layout of both a strong focus on mechanical hand Shoubi the balance, through Helibuju, optimal design structure, which makes Shoubibenshen as balanced. If the result does not meet the balance of practical work, set to balance the spring balancing mechanism.

Chapter 3 Theoretical analysis and design calculations

3.1 Motor Selection of the parameters calculated

3.1.1 Calculation of the parameters

1. If you drive the load in a straight line (through the ball screw, there

Specific to the design, because the stepper motor is driven rotary waist, form of exercise is the second pass. The following were the specific calculations.

Because there is only waist rotary motion friction torque, rotary circumferential direction in the absence of other torque in the rotary axes,

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3.1.2 Motor Choice Model

Based on the above results, and considering all factors, when the decision to choose Beijing Motor Technology Co., Ltd. and Lee (former Beijing Stone Motor Company's stepper motor, the specific model:

110BYG550B-SAKRMA-0301 or 110BYG550B-SAKRMT-0301 or 110BYG550B-BAKRMT-0301, the stepper motor high torque, low vibration, good overall performance, the parameters in Table 3-2.

One 110BYG550B-SAKRMA-0301-type stepper motor torque-frequency characteristic curve and the related technical parameters. Figure 3-3

Drive for the increasing frequency and boost, step angle of 0.36 ��. At the same time as the waist gear ratio 1:120, after slowing to pass through the stepper motor to the rotary axis, the actual rotary motor step angle will be the actual step angle of 1 / 120 (in theory, although in practice there is linear error space and gears, the actual return to the minimum step angle of the shaft is still too small, so the accuracy is very high, fully meet the positioning accuracy of robot requirements.

3.2 Calculation of hydraulic system design

3.2.1 determine the basic scheme of hydraulic system

Hydraulic actuators can be divided into hydraulic cylinders and hydraulic motors, hydraulic Gang achieve linear motion, the hydraulic motor to achieve rotary motion. Both characteristics and application of occasions Jianbiao 3-1:

Because the robot is designed to form cylindrical coordinates, and has 3 degrees of freedom, one for the back seat of the rotation, the two degrees of freedom for the movement of the arm. Taking into account the robot's working environment and load the layout and positioning accuracy of its requirements, and computer control factors, waist-driven rotary motor to achieve, the level of the robot arm and vertical arm single rod hydraulic cylinders are used to achieve linear reciprocating motion.

3.2.2 development of motion control loop hydraulic actuators

Hydraulic actuators to determine, its velocity and direction of control is the core issue of the hydraulic circuit.

Speed ​​control of hydraulic actuators by changing the flow of input or output, or change of use of enclosed space to achieve the volume. The corresponding methods are throttle speed, speed and volume of the volume of a combination of both cutting speed and direction control is logic control unit with a valve or to achieve. For the average small flow hydraulic system, through the valve to realize the organic combination of the required action. on the high pressure and large flow system, the use of cartridge valves and the pilot control valve The logic combination to achieve.

The design of the speed control of the main use of throttle, throttle by using relatively simple to implement, but the direction is controlled by solenoid valve to achieve.

3.2.3 Design of the hydraulic source system

Hydraulic system is entirely the work of media sources to provide hydraulic pressure, hydraulic pump is the core of the source. Throttle control system for general use quantitative pump oil, in the absence of other auxiliary oil source circumstances, hydraulic pump of the fuel supply to a large the needs of oil in the system, the excess oil back into the tank through the relief valve, relief valve control and at the same time play a role in stabilizing the oil supply pressure. Volume control system with variable pump more oil, with the safety valve to limit system maximum pressure.

Hydraulic oil purification plant is the source of essential components. The general entrance to pump crude oil filter to be installed into the system, the oil, upon request, through the fine filter filtered again. Impurities in order to prevent flow back into the fuel tank system, Set in the magnetic path back to the oil filter. According to the environment in which the hydraulic device and the temperature rise, we should also consider the heating, cooling and other measures.

The design of the hydraulic system, quantitative pump oil from the relief valve set V1 to adjust the system pressure. In order to ensure the cleanliness of hydraulic oil, hydraulic oil into the contaminants to avoid, so thick in the pump inlet filter installed, and in the pump exports to install fine on the loop filter for purification of hydraulic oil.

3.2.4 Hydraulic system diagram drawing

The hydraulic system of the robot as shown in Figure 3-2 (see drawing the fourth page,

It has a vertical arm up, down, horizontal arm of the protrusion, retrusion, and the implementation of the clamping gripper, open the three implementing agencies.

Among them, the pump is three-phase AC induction motor M by the drag, the system pressure it is set by the relief valve V1, 1DT determine the pros and cons of electric power source input and removed.

Taking into account the operational requirements of the gripper gently grab, the rapid release, the system uses a throttle effect, ranging from two-way throttle. When 5DT was electric, the working fluid through the throttle valve V5 into the plunger cylinder, Gripper leisurely step to achieve, when 6DT loss of power, the working fluid into the plunger cylinder, and achieving rapid release gripper.

In addition, the mechanical hand vertical lifting cylinder in the direction of the decrease of work load of gravity in the same direction with the decrease of velocity when the accelerating trend, for the smooth movement, while minimizing impact, vibration, ensure the safety of the system , formed by V2 loop equilibrium phase under the lift cylinder oil discharge chamber to provide a back pressure to balance gravity load.

3.2.5 identify the main parameters of the hydraulic system

The main parameter is the hydraulic system pressure and flow, they are designed hydraulic system, the main basis for selection of hydraulic components. Pressure depends on the external load, the flow depends on the velocity of hydraulic actuators and structural dimensions.

1. Calculation of the total mechanical load of the hydraulic cylinder

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3. To determine the main parameters of the hydraulic cylinder

Taking into account the characteristics of the robot, the system's rigidity and stability is very important. Therefore, the start point of the hydraulic cylinder bore stiffness of options to try to give priority to ensuring the manipulator structure and motion of the stability and security. As for the hydraulic cylinder work pressure and work rate cylinder, on the hydraulic system design stage, through the external hydraulic circuit, use the appropriate speed circuits and components to achieve. After careful analysis, considering all factors, initially to determine the hydraulic cylinder basic parameters are as follows,

Because the main function of telescopic cylinder is to achieve linear motion, in its axis does not bear the work load of dominant (because gripper clamp the workpiece, the force direction is perpendicular to the direction of the main axis to overcome the friction torque, which suffered Zaihe main radial load, the load moment of nature to produce bending. and because the robot requires a certain amount of flexibility, the level of the hydraulic cylinder piston rod requires a relatively large working stroke. also has a relatively large bending moment and long trip, which cylinder has a higher stability and stiffness requirements.

Therefore, the level of telescopic cylinder design, the first increase its flexural capacity, the second is the structure through a rational layout, to make it as large as possible stiffness. To this end, the design uses two guide rods, long stroke of the piston rod to meet the stability and orientation problems. On the other hand, in order to increase the structural rigidity and stability, and the two guide rod and the piston rod into the layout of the form of an equilateral triangle cross-section in order to increase the bending section modulus, but also greatly increased the stiffness of the hydraulic cylinder work.

Because the vertical load borne by the hydraulic cylinder means has some axial load, and there are large overturning moment (caused by the gravity of the workpiece. As hydraulic actuators, to meet the requirements of the driving force here is the easy, To resolve the key issue remains whether the structural design is that it has sufficient rigidity to resist overturning. Here, too, adopted the guide bar body set up around the four vertical lifting cylinder guide rod, the better solution to this problem.

4. Hydraulic cylinder strength of more nuclear

(1 piston rod diameter than the nuclear

3.2.6 Calculation and selection of hydraulic components

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References

1.������, ����, ���Ҳ�. ����CAN����Һѹ��������˿���ϵͳ�����ʵ��. ������Һѹ. 2003, (6): 90~92

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4.��ѧ��. �ɱ�̿�����(����ƪ). ����: ���ӹ�ҵ������, 2003.

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7.���, �Ա�, ʩ����. ���ϰ��˻�е�ֵ�����. ����һ�廯. 2005, (2): 43~45

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9.������, ������, ������. ��е���(�޶���). ������: ��������ҵ��ѧ������, 2003.

10.���. ����һ�廯����. ����: ��ѧ������, 2004.

11.���ﰲ, �ź���, �λ�. ��е���ӹ���. ����: ��ѧ������,2003.

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