automated welding

8/6/2019 automated welding

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Teknologi Dan Rekayasa

AUTOMATED WELDING


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AUTOMATED WELDINGObjective :

After studying this lesson, the

student can be identify theautomated welding.


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AUTOMATED WELDING For many years manual or stick

welding was used predominantly for

jointing metal. With the development ofgas shielded-arc welding equipment itbecame possible to resort to semi-

automatic techniques.


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AUTOMATED WELDING Although stick welding per se will

always play a useful role in many

fabricating processes, particularly insmall jobs shops and maintenancework, industries in general have to a

large extent adopted semi-automaticequipment.


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AUTOMATED WELDING Now many metal fabricating

manufacturers are beginning to realize

the necessity of moving even beyondthe semi-automatic processes andgoing to fully automatic welding

systems, even to the extent of usingcomputers to control the automatedequipment.


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ADVANTAGES OF AUTOMATED WELDING

Studies have shown that the best stickwelding operators working under the

most ideal conditions rarely with getmore than 25 to 30 percent arc time,that is, in any given work period only 25

to 30 percent of the time is actuallyspent welding. On the other hand,semi-automatic operators usually canachieve 50 to 75 percent arc time.


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However, management is finding thateven this increase in production

efficiency is not enough to meet thepresent-day technological demands onindustry.


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The need for more serviceful andquality goods at greater savings is

forcing industries to adopt bettercontrol techniques and more functionalmanufacturing procedures. Specially,

industry is facing the task of boatingproduction, turning out products ofbetter quality, at lower labor cost andgreater safety.


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By resorting to fully automated welding,poor and ineffectual welds, operator

inefficiency, and high manufacturingcost are reduced. Automated weldingnot only ensures faster deposition rates

but repeatedly produces welds ofconsistent quality.


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Although the initial cost of converting toautomated welding may be relatively

high at the outset, the consensus ofwelding engineers is that we cannotafford not to. The eventual savings in

manufacturing cost, by and large, willmore than make up for any expenseincurred in setting up a modernautomated system.


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AUTOMATED WELDING SYSTEMS

In general, there are two basic systemsfor automated welding. With one, the

welding equipment is stationary andthe work flows around the welders.With the alternate plan, the work

remains stationary and the weldingequipment moves on a track to thedesignated position where welds are tobe made.


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Either system is designed to giveprecise control over every welding

factor, such as presurge time, hot startlevel, pulsation delay, initial current,upslope, weld taper delay, weld

current, pulse level, high and low pulsetime, final taper current, final current,postflow time and post heat.


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There are virtually no limits as to thekind of welding that can be automated.

Submerged arc, resistance, and Tigand Mig processes can readily beautomated. Mig welding is oftenpreferred because of its greaterversatility. This includes spray arc,short arc, cored wire and CO2.


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TYPES OF AUTOMATED WELDING SYSTEMS

Generally speaking, there are noconventional or standard types of

automated welding systems. Outside ofthe regular welding units, most systemsare specifically designed to function for

an existing work flow configuration.


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Therefore, the type of system useddepends on the product being

manufactured, the manner in whichproduction is processed, and theexisting type of plant facilities.

Accordingly, automation is strictly anengineering design problem ofindividual plants. Several examples toillustrate this point follow.


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In one automotive industry, increasedproduction is achieved by means of

traversing robot which moves on floor-mounted tracks or overhead rails andperforms welding operations on carbodies or parts on an assembly line.Affixed to the robot, a spot welding gunis carried down the assembly line andautomatically performs the desired

welds.


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Another example is the manufacturer ofmotor stators which developed an

automated system that :1. picks up and orients the correct

number of laminations and hands

them to the operator


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1. joins the laminations with foursimultaneous Tig welds at 90-degree

intervals around the circular stator and2. presses a cap ring over the stator and

gas metal-arc spot welds it in place.


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Connected to the power sources arefour stationary tig welding torches.

Welding is accomplished under thetorches on a turntable. A ram smoothlylifts the stator unit past the torches.


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A further example is that of amanufacturer of hydraulic equipment.

Here an automated submerged arcsystem was designed to weld cylinders.This welding system moved on a floortrack 50 feet long. The ram whichcarries a welding head has an eight-foot stroke.


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Welding current is supplied by aconstant voltage power source which is

mounted on the frame of the headstockto allow it to move with the system. Airbrakes hold the entire unit at any pointon the track.


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The fact that one man can often do 80percent of the work of two men led a

manufacturer of dual wheels for alltypes of farm equipment to develop anautomated welding system. In thiscase, the automatic welders are usedto join strips of metal into cylindrical rimblanks. These blanks are first runthrough an expander to form the proper

configuration.


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A fixture clamps the rim blanks in placeand holds the joint sides together

during welding. A welding head whichis mounted on a carriage moves overthe rim and welds the joint.


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PROGRAMMED WELDING

The ultimate in any automated weldingsystem is programmed welding where

numerically controlled (N.C.)equipment is utilized. Just as N.C. iscurrently used in many machining

operations, industries are finding thatfurther economies are achieved byresorting to numerically controlled unitsfor production welding.


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PROGRAMMED WELDING

With programmed welding, all of thewelding operations are preset and the

entire welding process is initiated withthe press of a button. The sequence ofoperations can be pre-programmed onpunched tape to weld numerousdifferent configurations automatically.


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PROGRAMMED WELDING

A typical example is the manufacturerof heat exchangers who, when

converting to automatic numericalcontrol, found that welds could beexecuted ten times faster.


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PROGRAMMED WELDING

The N.C. unit automatically aligns thefixture containing the heat exchanger,

inserts a shot pin, clamps the fixture,positions the assembly for welding,initiates the welding torch guidancesystem, and returns the exchanger to

the start position.


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PROGRAMMED WELDING

The only manual operation required isturning the fixture 180 degrees for

welding the opposite end of theexchanger. While one unit is beingwelded, another is being loaded in asecond fixture. This new system

requires only 10 percent of the 70 to 80minutes needed to do the workmanually.


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PROGRAMMED WELDING

The old method required putting partstogether manually, placing them on a

hand-turned spindle, then Mig-weldingmanually one side of the spiral at atime. With the new system, the partsare rotated past two stationary Mig

welding torches feeding 1/16 flux-

core wire.


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PROGRAMMED WELDING

Torches positioned on both sides of thehelix operate simultaneously,

producing a stronger weld than beforebecause of better heat penetration andthe flux-core shield.


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automated welding

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