International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 3 - May 2014
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1,2,3,4 Student, 5 Assistant Professor
K.J College of Engineering, Pune, India
Abstract— The key role of the project is to design and manufacture the pick and place system which will perform on the assembly line of thermostat valve. The components which were to be handled and assembled were small. Accurate and quick system was required so a new pick and place system with quick and accurate motions was to be designed. Cartesian coordinate system is used and vacuum grippers are used to pick and place the components and the movement is carried with the help of pneumatic cylinders .The system is very important to eliminate human errors and to get more precise work. It can also save the cost in long term and help to solve problems and task that cannot be done such as on time temperature area narrow area and very heavy load things.
Index Terms— Assembly line, Cartesian co-ordinate, Flexibility
Pick and Place.
I.
INTRODUCTION
The robot sicence is an automatic, sevro-controlled, freely programmable, multipurpose ,with several areas, for handling the workpieces, tools or special devices. This article is based d) Equipment - this includes tools and mechanical fixtures. e) Characteristics- that makes robot different from regular machinery are that, robots are capable of delivering a job of quality, with reduction in rejection. They can work in hazardous environment and can increase productivity, safety and efficiency of process. They can also work continuously without experiencing fatigue or boredom and can perform multiple tasks simultaneously.
II.
DESIGN CONSIDERATIONS
For designing the Cartesian co-ordinate system robot some important considerations are done in system specification, system performance and configuration and in design of different components of the robot. In system specification, robot reach, load capacity, work envelope and range is considered. Its drive configuration, joint travel range, number on the research project which is an autonomous robot to be use in assembly line. The robot is powerful, reliable and can be use in hot temperature area where a human after working for so long can become sick and exhausted. This robot is able of degrees of freedom is considered in its configuration. For its performance system velocity, accuracy, precision, repeatability and component life are taken into its considerations. Detailed design of robot structures and joints, actuators, its transmission and wiring and routing of cables to work in assembly line for picking up one object and placing it into the other. The most apparent reasons that are associated in installing of robotic systems in assembly line are;
1) Saving of manpower.
2) Improved quality & efficiency.
3) Ability to work in any hostile environment.
4) Increased consistency & flexibility.
The robot, which we have been able to make, is completely and hoses is done.
III.
DESIGN OF RELIABLE MECHANICAL
JOINTS
The function of a joint is to permit relative motion between two links or arms of a robot. It provides controlled relative motion between two links (input and output). Generally one joint provides the robot with one degree of freedom. There are various joints such as the linear joints, orthogonal joints, rotational joint, twisting joints and revolving joints. Of the given joints the linear is the easiest to manufacture and is best
Independent and intelligent. In this robot we will use the pneumatic power. The idea is to reduce manual controlled system, which always needed a human interface. This Robotic system is feasible by small and local industries having small scale production. The system is a reliable, can reduce the cost suited for our assembly line. Thus linear joints are used. The cost of linear joints is very less and can best satisfy our requirement. However based on the strength and weight to be lifted various types and quality of hinged linear is used.
IV.
MANIPULATOR DESIGN of production, and reduce the manpower and human workload.
A robot can include any of the following components; a) Effectors - like "arms", "legs", "hands", "feet" etc.
A manipulator is generally mounted on a track or suspended from a track that is capable of reaching various distances and locations. It is used to move materials, tools and objects without direct human contact. It consist of two sections b) Sensors - parts that act like senses and can detect objects and converts the object`s information into symbols that computer system can understand. namely the body or arm and the wrist assembly. c) Computer - the brain that contains instructions to control the robotic system.
A. Design of body
The body is used to position the object in the robot’s work envelop. And thus by employing the concept of value engineering proper design can help reduce the weight of the
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 3 - May 2014 body and also the amount of materials used. Generally to optimize both material cost and the manufacturing cost the arm is made up of different components and then is assembled together, thus saving the material and reducing the cost. In this project Cartesian coordinate design configuration used as it is the best suited one as per the requirement
B. Design of wrist assembly
It is used for the orientation of the object in the work envelop.
The end effector is attached to the wrist assembly. Wrist assembly has three degrees of freedom pitch, roll and yaw.
However for simple pick and place application keeping in mind the complexity of manufacturing of the wrist assembly the end effectors can be attached to the arm directly using welding. Pneumatic cylinder is used for controlling the end effectors. Thus contributes significantly in reducing the cost of the robot.
C. ROBOT DESIGN CONFIGURATON
It fulfill the requirements like, less floor area, accuracy, low cost, simple in operation and construction.
In Pick and Place system Cartesian coordinate type is selected.
This configuration provides rectangular work envelope. The three major axes of the manipulator are rectilinear and provide movements along these axes. No rotational movement is available.
The inverse kinematic solution for this configuration is trivial. This configuration produces robots with very stiff structure .
V.
DESIGN OF END EFFECTOR
The arm is responsible only for positioning the object. It’s the end effector that interacts with the object. The hand of the robot is considered as the end effector. The various end effectors are mechanical, grinders, welders and ,adhesive, magnetic and vacuum. Here we choose vaccum gripping action without cups. A gripper used for lifting and placing objects is simple to design and manufacture. A vacuum can use the pneumatic power and thus reduce the running cost and also perform complex tasks.
VI.
MOVEMENT OF THE ROBOT
For the robot to reach different locations and perform the tasks it has to move in axis. Thus depending up on the requirement pneumatic cylinder is used for the picking and placing the object in the assembly line. The required air is supplied from the compressor. Here pneumatic is used with linear movement of cylinder. Thus significantly reducing the cost of the robot.
VII.
PNEUMATIC CIRCUIT
A pneumatic logic system is generally used to control the industrial robots. Since electronic circuits are not used thus precise and accurate pneumatic circuits are designed and implemented. Sequential circuits are designed so that each cylinder is actuated at proper sequence and are also kept active for the desired period of time. This the only challenge in a low cost robotic arm is designing of the pneumatic circuit.
VIII.
MATERIAL SELECTION
Material selection is one of the most important factors in reducing the cost of the robot. Materials are selected in such a way that there is no compromise in minimum design requirement. Here to we choose to use the cast iron as it has high strength, easy weldability and low cost. Gripper is made of mild steel so as to get proper strength and to get easy machining operations done. The lower body and the base is made of iron in order to provide the required counter weight so that the stability of the robot in not lost. Depending upon the weight to be lifted the material selection varies. However to reduce the cost and ease of manufacturing we can use iron if weight considerations are not present.
IX.
DRIVE SYSYTEM
The drive chosen based on
 The power consumption
 Repeatability
 Positional accuracy
 Stability
 Speed of operation
 Reliability
 Cost
Out of Hydraulic, electrical and pneumatic; Pneumatic drive make use of compressed air which is readily available and non-flammable. Pneumatic drives are of lighter construction.
Advantages of using Pneumatic drive
 Freely available from atmosphere
 Easily transportable in vessel and pipes
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International Journal of Engineering Trends and Technology (IJETT) – Volume 11 Number 3 - May 2014
 Clean system. It has self cleansing properties.
 The pressure, speed and forces can be controlled easily
 Low cost of maintenance
X.
CALCULATIONS
A. Selection of end effecter cylinder
Vertical Cylinder
S = 100mm
Load = 10kg or 10*9.81 = 98.1N
Pressure = Load/Area
= L/ (pi*d²/4)
= 98.1/ (3.147*0.032²/4)
= 1.22 bar
Since the available standard cylinder for 100mm stroke of
FESTO is of diameter 40mm and stroke length 100mm, the cylinder used for the end effectors are selected with the dimensions of 40mm x 100mm.
B. Selection of body cylinders
Horizontal Cylinder
S = 250mm
Load = 18kg or 18*9.81 = 176.58N
Pressure = Load/Area
= L/(pi*d²/4)
= 176.58/(3.147*0.040²/4)
= 1.509 bar
Since the available standard cylinder for 250mm stroke of
FESTO is of diameter 40mm and stroke length 250mm, the cylinder used for the end effectors are selected with the dimensions of 40mm x 250mm.
C. Selection and calculations of end effector
Due to the smooth surface and hollow geometry of the object to be moved, Vacuum Gripper is used as an end effector.
Weight to be lifted = 8 gm d=1.12*sqrt[(m*S)/(P u
*n*µ) ] where, m =weight to be lifted = 0.008gm
S= factor of safety= 2
P u
=vacuum pressure= 88kpa=0.88bar
n =number of pads=1
µ=coefficient of friction=0.5
d= diameter of the hole required for given vacuum d= 1.12*sqrt[(0.008*2)/(0.88*1*0.5)]
=0.2135cm
=2.135mm
Due to surface roughness of the object to be moved and the absence of the rubber pad in the vacuum gripper, the following diameter was not sufficient for the given vacuum.
So the diameter of the hole for the required vacuum is increased to 5.4mm.
XI.
CONCLUSION:
The design and manufacturing of a Cartesian co-ordinate system robot for the movement of the given Byproduct has been performed effectively. The operation and working of the various components of the robot and end effector has been tested and the required modifications have been done. The given objective of designing a Cartesian co-ordinate system robot for effective movement of the byproduct in the assembly line has been accomplished. The robot has fulfilled the requirements that had to be met likewise sensitivity, accuracy, precision, reliability, rigidity.
XII.
ACKNOWLEDGMENT
This work was supported by the staff support and facilities provided by the department of mechanical engineering, KJ college of engineering, Pune, India.
XIII.
REFERENCES
[1]. Deb, S. R. (n.d.). Robotic technology and flexible automation.
[2]. Robotics by MT Puranik, RR Ghorpade & Dr. MM Bhoomkar
[3]. Groover, M. P., & Weiss, M. (n.d.). Industrial robotics.
[4]. Khurmi, R. S., & Gupta, J. K. (n.d.). Machine design.
[5]. Industrial fluid power by Lt. col. Ashok Kumar C.P
[6]. Rajput, R. K. (n.d.). Robotics and industrial automation.
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