Me10b017 (Robotic Welding)

7/28/2019 Me10b017 (Robotic Welding)

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Twin wire Robotic

welding

Lab-1

METEROLOGY & MACHINING LAB

SUMIT JADHAV

ME10B017 | Lab-1


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OBJECTIVE:

To prepare a weld bead of MIG welding on Mild Steel Plate using Time Twin Robotic Welding Station

with different mode:

1. Continuous Mode2. Pulse Mode

APPARATUS REQUIRED:

1. KUKA Twin wire robotic welding apparatus.2. A darkened glass cabin to avoid damage by welding.3. Steel wires coated with copper of 0.8 mm diameter.4. A DC power source with positive normally connected to the torch and the work piece to

negative.

5. The wire feed unit.6. Control devices to control the robot.7. A gas flow control device.


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THEORY :

The Robotic Welding uses the concept of MIG welding where a vibrant inert atmosphere is created by

the presence of inert gases to avoid the oxidation of molten metal which is formed during the welding

process. The inert gas used is 80% Argon and 20% Carbon Dioxide.

The twin wires used in this process is made of steel coated with copper which is around 0.8 mm

diameter. This is continuously kept in contact with the work piece for welding process to take place. The

two wires are connected to the opposite poles of the transformers. These two wires are of opposite

polarity and when they come into contact near the work piece, an electric arc is produced which helps in

melting the material and this molten material diffuses into the two parts to be joined, thereby, creating

a strong bond.

Welding is usually done in two ways:

1. Continuous Mode:In this mode, current is passed through the electrodes all along the path of the welding. Hence,

there is a continuous formation of weld pool and solidification occurs in the aftermath.

2. Pulse mode:Here current is passed through the electrodes for specific duration. Hence, there is some

distance between the formation of weld pools and weld beads. The welding here is intermittent

and not continuous.

When the robot is mastered, the axes are moved into a defined mechanical position which is called

mechanical zero position. Once the robot is in this position, the absolute encoder value for each axis is

saved.

The various coordinate systems which can be defined in this are:

1. Axis specific motion:Each robot axis can be moved individually in positive or negative direction. Generally, the angles

of rotation are the inputs in this system. Therefore, the final position aimed to be welded is

attained by rotation of two or more arms. The input angles of rotation for each of these arms

are independent of each other.

2. World Coordinate System:Fixed, rectangular coordinate system whose origin is located at the base of the robot. All

distances are measured from this position and the particular path required for accomplishing a

task can be achieved by setting the various coordinates in this system.


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3. Tool Coordinate System:Rectangular coordinate system, whose origin is located at the tool.

4. Base Coordinate System:Rectangular coordinate system which has its origin on the work piece that is to be processed.

PROCEDURE:

1. The voltage and current values were set in the power source according to the requirementwhich depends on the thickness of the work piece to be welded and also the mode of the

welding.

2. The mode of welding, either continuous or pulse was set.3. The settings were saved on each of the transformer giving them the same program number.4. Using the handheld device, the same program number was called and then the points were

defined through which the arm moves. This is done so as to avoid rapid collision of the weld arcwith the work-piece and to ensure a smooth process without any collision.

5. Also, the welding process was started by using the TECHNOLOGY menu in the software. Themachine was set in automatic mode and then the welding process was started.

RESULT:

OBSERVATION:

The weld pool deposited on the work piece in continuous mode appears to be rough with irregularities

in the shape and deposition of molten metal in the joint whereas, the weld pool deposited on the work

piece in pulse mode appears to be quite smooth and regular in shape with not much variation in the

deposition of molten metal at the joint.


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Benefits of Robotic Welding:

1. Automation reduces the performance of certain repetitive tasks.2. Decreases the error potential which means decreased scrap and rework.3.

Increased production rates.

4. Welding can even be done in certain places where it might be difficult to reach out for if donemanually.

CONCLUSION:

1. Robot welding has raised the production rates at a tremendous rate that could have beenpossible with the manual welding.

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Manual risk is reduced to a huge extent as there is no need of working in hazardous conditions.3. Besides, the product will be neat, smooth, precise and accurate to the dimensions required as it

is pre-programmed.

Documents

Me10b017 (Robotic Welding)