Index

Sr.No.                            CONTENT                                               PAGE No.

      1.                                            INTRODUCTION.                                                                4

      2.                                           CLASSIFICATION.                                                               5

3.                                                                             DEFINITION OF RESISTANCE

                                              WELDING.                                                                             6

      4.                                           PRINCIPLES OF RESISTANCE WELDING.                      7

      5.                                          WELDING PARAMETERS.                                                  8

      6.                                          GENERATION OF HEAT.                                                     9

      7.                                          ELECTRICAL CONSIDERATIONS.                                   11

      8.                                          PARTS OF A TYPICAL ROBOT.                                        15

      9.                                         METHODS OFCONTROLING A ROBOT.                          23                        

     10.                                        SPECIFICATIONS OF ROBOT.                                           25

     11.                                        FEATURES OF S-900iB                                                        26

     12.                                        FEATURES OF LR MATE                                                    28

     13.                                        FEATURES OF R-2000iB AND R-J3iC                               30

     14.                                        FEATURES OF ROBOT M-710iC                                       31

     15.                                       CLASSIFICATION OF ROBOT

                                                 ON THE BASIS OF PAYLOAD.                                          32

     16.                                       CONCLUSION.                                                                     33

     17.                                       BIBLOGRAPHY.                                                                   35                           

1.             Introduction

                                                                                Spot welding is the most common welding application             found in the manufacturing field. Also referred to as resistance welding, it is used             to join thin metals together.

                                Robot welding is the use of mechanized programmable tools (robots),      which completely automate a welding process by both performing the weld and             handling the part. Processes such as gas metal arc welding, while often     automated, are not necessarily equivalent to robot welding, since a human      operator sometimes prepares the materials to be welded. Robot welding is                commonly used for resistance spot welding and arc welding in high production               applications, such as the automotive industry.

                                Robot welding is a relatively new application of robotics, even though     robots were first introduced into US industry during the 1960s. The use of robots            in welding did not take off until the 1980s, when the automotive industry began      using robots extensively for spot welding. Since then, both the number of robots        used in industry and the number of their applications has grown greatly. Cary and    Helzer suggest that, as of 2005, more than 120,000 robots are used in North             American industry, about half of them pertaining to welding. Growth is primarily    limited by high equipment costs, and the resulting restriction to high-production              applications.

                                Robot arc welding has begun growing quickly just recently, and already it                 commands about 20% of industrial robot applications. The major components of       arc welding robots are the manipulator or the mechanical unit and the controller,    which acts as the robot's "brain". The manipulator is what makes the robot move,             and the design of these systems can be categorized into several common types,       such as the SCARA robot and Cartesian coordinate robot, which use different coordinate systems to direct the arms of the machine.

                                The technology of signature image processing has been developed since the late 1990s for analyzing electrical data in real time collected from automated,      robotic welding, thus enabling the optimization of welds.

                3. Definition of Resistance Welding

                                                Resistance Welding is defined as the joining of two pieces of                                               metal       by application of Heat and Pressure.

                                                The heat is generated by the RESISTANCE offered by these parts to                                       the passage of current.

4.             Principles of Resistance Welding

·          Squeeze time: Time set to ensure predetermined welding force                                                 before current flow.

·          Weld time:                Time for which welding current is switched on.

·          Hold time:      Time electrodes are held together under pressure                                 after weld time.

·          Cool time:                 Current off time between successive current pulses in                          pulsation or seam welding.

                5.             Welding Parameters 

                                Squeeze Time                                   1 to 99 cycles (all series)

                                Slope Time                           1 to 30 cycles (all series)

                                Weld-1 Time                                   0 to 99 cycles (all series)

                                Cool-1 Time                                                          0 to 99 cycles (all series)

                                Weld-2 Time                                   0 to 99 cycles (all series)

                    Down Slope Time                          0 to 99 cycles (all series)

                                Cool-2 Time                                                   0 to 99 cycles (all series)

                                Weld-3 Time                                  0 to 99 cycles (all series)

                                Hold Time                                                 1 to 99 cycles (all series)

                                Off Time                                         4 to 99 cycles (all series)

                6.             Generation of Heat

                                                                                Heat energy is generated when ever electrical current is           passed through an electrical resistance.

                Q = I²Rt

                Q = Watt-seconds or joules

                i   = Welding Current in amperes

                R = Electrical Resistance related with   material properties and electrode force in           Ohms

                t  = Weld Time in cycles (1 cycle= 20 milli sec)

                                Spot welding is a type of resistance welding used to weld various sheet            metals. Typically the sheets are in the 0.5-3.0 mm thickness range. The process    uses two shaped copper alloy electrodes to concentrate welding current into a     small "spot" and to simultaneously clamp the sheets together. Forcing a large                current through the spot will melt the metal and form the weld. The attractive       feature of spot welding is a lot of energy can be delivered to the spot in a very            short time (say ten to one hundred milliseconds). That permits the welding to         occur without excessive heating to the rest of the sheet.

                A MILLER SPOT WELDER

                                                The amount of heat (energy) delivered to the spot is determined by        the resistance between the electrodes and the amplitude and duration of the   current. The amount of energy is chosen to match the sheet's material properties, its thickness, and type of electrodes. Applying too little energy won't melt the              metal or will make a poor weld. Applying too much energy will melt too much       metal make a hole rather than a weld. Another attractive feature of spot welding             is the energy delivered to the spot can be controlled to produce reliable welds.

                Applications of Spot Welding

                1.             Spot welding is typically used when welding particular types of sheet                                        metal. Thicker stock is more difficult to spot weld because the heat flows                      into the surrounding metal more easily. Spot welding can be easily                                           identified on many sheet metal goods, such as metal buckets. Aluminum                         alloys can also be spot welded. However, their much higher thermal                                         conductivity and electrical conductivity mean that up to three times higher                            welding currents are needed. This requires larger, more powerful,and more                   expensive welding transformers.              

                2.             Perhaps the most common application of spot welding is in the automobile                            manufacturing industry, where it is used almost universally to weld the                             sheet metal to form a car. Spot welders can also be completely automated,                              and many of the industrial robots found on assembly lines are spot welders,                       the other major use for robots being painting.

                3.             Spot welding is also used is in the orthodontist's clinic, where small scale                  spot welding equipment is used when resizing metal "molar bands" used in                               orthodontics.

                4.             Another application is spot welding straps to nickel-cadmium or nickel-                  metal-hydride cells in order to make batteries. The cells are joined by spot                     welding thin nickel straps to the battery terminals. Spot welding can keep                               the battery from getting too hot -- as might happen if conventional                                              soldering were done.

Spot welding: KUKA industrial robots welding a car body in the white section of a production line.

                7. Electrical Considerations

                                                                The basic spot welder will consist of a power supply, an           energy storage unit (e.g., a capacitor bank), a switch, a welding transformer, and          the welding electrodes. The energy storage element allows the welder to deliver       high instantaneous power levels. If the power demands are not high, then the                energy storage element isn't needed. The switch causes the stored energy to be        dumped into the welding transformer. The welding transformer steps down the              voltage (and steps up the current). An important feature of the transformer is it     reduces the current level that the switch must handle. The welding electrodes are       part of the transformers secondary circuit. There's also a control box that                 manages the switch and may monitor the welding electrode voltage or current.

                                The resistance presented to the welder is complicated.There's the resistance            of  secondary winding, the cables, and the welding electrodes. There's the contact                 resistance between the welding elecrodes and the workpiece. There's the resistance of the workpieces. There's the contact resistance between the                 workpieces.

                                At the beginning of the weld, the contact resistances are usually high, so                 most of the initial energy will be dissipated there. That heat and the clamping              force will soften and smooth out the material at the electrode-material interface     and make better contact (that is, lower the contact resistance). Consequently,           more electrical energy will go into the workpiece and the junction resistance of      the two workpieces. As electrial energy is delivered to the weld and causes the           temperature to rise, the electrodes and the workpiece are conducting that heat        away. The goal is to apply enough energy so that a portion of material within the            spot melts without having the entire spot melt. The perimeter of the spot will        conduct away a lot of heat and keep the perimeter at a lower temperature. The               interior of the spot does not have as much heat conducted away, so it melts first.    If the welding current is applied too long, the entire spot melts, the material runs             out or otherwise fails, and the "weld" becomes a hole.

                                The voltage needed for the welding depends on the resistance of the        material to be welded, the sheet thickness and desired size of the nugget. When           welding a common combination like 1.0 + 1.0 mm sheet steel, the voltage              between the electrodes is only about 1.5 V at the start of the weld but can fall as             low as 1 V at the end of the weld. This drop in voltage stems from the resistance    reduction caused by the steel melting. The open circuit voltage from the           transformer is much higher than this, typically in the 5-10 V range, but there is a   very large voltage drop in the electrodes and secondary side of the transformer            when the circuit is closed.

Due to changes in the resistance of the metal as it starts to liquefy, the                 welding process can be monitored in real-time to ensure a perfect weld every                 time, using the most recent advances in monitoring/feedback control      equipment. The resistance is measured indirectly, by measuring the voltage at                 and current through the electrodes.

                                Resistance welding is capable of processing high volumes of product using                localized heat and low fumes/vaporous emissions.  Using integrated part         handling, standard or existing resistance welding equipment can be fully   automated

                The actuators were developed in the following order:

1.        Mechanical actuators-(Bulky, heavy).

2.        Pneumatic actuators-(Possibility of air leakage, slow response, not process friendly during mass Production)

3.        Servo actuators-(light, flexible, very fast, authentic-reliable)

                A brushless DC servo motor is used to drive the robot.

                There are two basic categories of welding automation: semi-automatic and fully      automatic:

                Automated Welding

·      Semi-automatic welding occurs when an operator manually loads the part(s) into the welding fixture. The torch/part motions and welding parameters are controlled by a weld controller to ensure a quality, repeatable weld. When the weld is completed, the operator removes the completed part and then the process starts over.

·      Fully automatic welding utilizes a custom machine or succession of machines to load the work piece, place the part or torch into position, effect the weld, supervise quality control, and then when the product is finished, unload it. If necessary, additional "part in place" and final product quality checks may be designed into the machine. The details of the specific operation designate whether a machine operator may or may not be necessary.

                Welding Applications most suited for Automation:

                                To benefit most from industrial automation, applications must have one or            more of the following three key requirements:

                     Quality or critical function welds.

                     Repetitive welds on identical parts.

                     Parts with significant accumulated value prior to welding.

                Batteries, capacitor cans, solenoids, sensors transducers & instrumentation, metal   bellows & seals, relay cans & enclosures, light bulb elements, fuel filters,      thermos flasks, medical components, nuclear devices, pipe to fittings, transformer cores, valve elements and airbag components are excellent candidates for           industrial automation. However, welding automation is not limited to precision       devices such as these. Companies that make limited amounts of product may          benefit from a semi-automatic system but might not be the best candidates for        fully automated welding systems.

A SPOT WELDING ROBOT

                ROBOT SPOT WELDING

                                                Automatic welding imposes specific demands on resistance welding          equipment. Often, equipment must be specially designed and welding procedures             developed to meet robot welding requirements.

                                The spot welding robot is the most important component of a robotized                 spot welding installation. Welding robots are available in various sizes, rated by               payload capacity and reach. Robots are also classified by the number of axes.  A      spot welding gun applies appropriate pressure and current to the sheets to be                 welded. There are different types of welding guns, used for different applications,    available. An automatic weld-timer initiates and times the duration of current.

                                During the resistance welding process the welding electrodes are exposed                 to severe heat and pressure. In time, these factors begin to deform (mushroom)             the electrodes. To restore the shape of the electrodes, an automatic tip-dresser is    used.

                                One problem when welding with robots is that the cables and hoses used   for current and air etc. tend to limit the capacity of movement of the robot wrist.        A solution to this problem is the swivel, which permits passage of compressed       air, cooling water, electric current and signals within a single rotating unit. The           swivel unit also enables off-line programming as all cables and hoses can be             routed along defined paths of the robot arm.

               8. Parts of a Typical Spot Welding                             

 Robot

                1. SPOT WELDING GUN

                Spot welding guns are normally designed to fit the assembly. Many basic types        of guns are available, the two most commonly used being the direct acting             type, generally known as a "C"-type gun, where the operating cylinder is                connected directly to the moving electrode, and the "X"-type (also known as          "Scissors" or "Pinch") where the operating cylinder is remote from the moving      electrode, the force being applied to it by means of a lever arm. C guns are              generally the cheapest and the most commonly used. There are many     variations available in each basic type with regard to the shape and style of the          frame and arms, and also the duty for which the gun is designed with reference        to welding pressure and current.

                X TYPE GUN:

                C TYPE GUN:

Pneumatic guns are usually preferred because they are faster, and they apply a         uniform electrode force. Hydraulic spot welding guns are normally used where                 space is limited or where high electrode forces are required.

                2. WELD TIMER

                                 An automated spot welding cell needs control equipment to initiate and   time the duration of current. A spot weld timer (weld control unit) automatically           controls welding time when spot welding. It also may control the current                magnitude as well as sequence and time of other parts of the welding cycle.        

 3. ELECTRODE TIP DRESSER

                                The function of the electrodes is to conduct the current and to withstand                the high pressures in order to maintain a uniform contact area and to ensure the continued proper relationship between selected current and pressure. Uniform         contacting areas should therefore be maintained.

                                Good        weld quality is essential and depends, to a considerable degree,                 upon uniformity of the electrode contact surface. This surface tends to be            deformed (mushroomed) with each weld. Primary causes for mushrooming are         too soft electrode material, too high welding pressure, too small electrode        contact surface, and most importantly, too high welding current. These conditions cause excessive heat build-up and softening of electrode tips.                Welding of today’s coated materials also tends to contaminate the face of the        electrodes.

                                As the electrode deforms, the weld control is called upon to "step" up the               welding current in order to compensate for "mushroomed" weld tips. Eventually,       the production line will have to be shut down in order to replace the electrodes or   to manually go in and hand dress the electrodes. This process will improve the                 weld cycle but in either case, the line is stopped and time is lost. Furthermore the    deformed electrodes have caused unnecessary high consumption of energy and                electrodes.

                                In automatic tip dressing, a tip dresser is mounted on the line where it     can be accessed by the welding robot. The robot is programmed to dress the              electrodes at regular time intervals. The dressing can be done after each working cycle, after every second cycle, and so on. It depends upon how many       spot-welds are done in each cycle. For welding in galvanized sheet, dressing             after about 25 spot-welds is recommended. The dressing takes approximately 1                to 2 seconds, and is performed when the work pieces are loaded, unloaded and         transported.  Maintaining proper electrode geometry minimizes production                downtime and utility costs and increases weld efficiency.

                4. A SPOT WELDING SWIVEL:                               

                                A major advancement in resistance spot welding is the swivel. This unit permits passage of compressed air, cooling water, electric current and signals                through different channels within a single rotating unit.

                                This invention greatly improves total efficiency of robotic spot-weld     installations. Electrical connection between swivel and transformer is minimal                thus permitting maximum utilization of access to spot-weld areas.

BASIC ADVANTAGES OF A SPOT WELDING SWIVEL:

·         Less work space needed -No mass of cables and hoses hanging from the robot arm, resulting in floor space economy.

·         Improved accessibility - Since no limitation on the robot wrist caused by any cables or hoses.

·         Improved safety - Greatly improved safety factors through reduction of air, electric and water lines; now limited to quick-connect piping, and hoses within robot arm.

·         Saving in capital equipment - Compact weld-gun assembly accessible to areas formly blocked by transformer, cables, and control boxes. More welds per station means big savings through fewer work stations and less capital equipment.

·         Reduced try-out costs - No un-defined cables exist on the robot, which reduces programming time to minimum. True off-line programming is now a reality.

 The swivel, which fits directly onto the weld-gun fixture plate without any hoses    or cables, ensures the highest quality condition of the spot-weld. No electrical                 degeneration on cables and no hoses that wear.

Thus,

                A spot welding apparatus comprises of:

                (1) A welding gun having a pair of opposing welding electrodes either one of           which is movable towards the other to apply a pressure onto a work and away from the other to release the pressure.

                 (2) A servomotor attached to the welding gun for adjusting the pressure applied     to the work through movement of the movable welding electrode (THE       PRESSURE CAN ALSO BE APPLIED MECHNICALLY OR   PNEUMATICALLY).

                (3) A servomotor controller for controlling an operation of the servomotor.

                (4) A welding current regulator for adjusting a value of welding current applied        through the opposing electrodes to the work.

                (5) A weld-interval timer arranged for adjusting at least one weld time interval        and weld timing for the welding current and the pressure both applied to the           work, and a spot welding controller electronically connected to the servomotor      controller, the welding current regulator and the weld-interval timer, for    simultaneously and arbitrarily adjusting a welding condition, namely the welding      current, the pressure, the weld time interval..

9.             Controlling a Spot Welding Robot

                 1. A method of controlling a spot welding robot comprising the steps of:

                (a)            Measuring by a robot controller a time elapsed until said robot controller                receives a pressurization completion signal from a spot welding gun after said               robot controller issues a pressurization command to said spot welding gun;

                (b)            Setting and storing thus measured value into a memory of said robot        controller as a time required for pressurization for said spot welding gun;

                (c)            Calculating a movement time required for the completion of the                             positioning of said robot after the start thereof in the case of controlling a robot       by said robot controller to execute a spot welding operation using the spot              welding gun specified in step (a); and

                (d)            Issuing a gun pressurization command to said welding gun by said robot    controller, at the point when a time obtained by subtracting said elapsed time             from said movement time after issuing said positioning command to said robot       from said robot controller has elapsed.

                2. A method of controlling a spot welding robot according to claim 1, further         comprising the steps of:

                Executing plural number of times of measurement of said elapsed time of step (a)   for the same gun;

                Finding a mean value of said actually measured values; and

                Storing said mean value into said memory of step (b) as a time required for              pressurization for said welding gun.

                3. A method of controlling a spot welding robot according to claim 1, wherein

                Said time required for pressurization to be stored into said memory of said robot      controller of step (b) is the number of processing periods obtained by dividing               said movement command to said robot by predetermined processing cycles.

                4. A method of controlling a spot welding robot comprising the steps of:

                (a) measuring by a robot controller a time elapsed until said robot controller           receives a pressurization completion signal from a spot welding gun after said robot controller issues a pressurization command to said spot welding gun;

                (b) Setting and storing thus measured value into a memory of said robot controller as a time required for pressurization for said spot welding gun;

                (c) calculating a movement time required for the completion of the positioning of said robot after the start thereof, in the case of controlling a robot by said robot            controller to execute a spot welding operation by said spot welding gun in (a);

                (d) Comparing said time required for pressurization with said movement time;

                (e) causing said robot controller to issue a gun pressurization command to said         welding gun simultaneously with the issue of said robot positioning command, if             said time required for pressurization is equal to or more than said movement           time; and

                (f) Causing the robot controller to issue the gun pressurization command to said      welding gun at the point when a time obtained by subtracting said elapsed time             from said movement time after the issue of said positioning command to said         robot by said robot controller has elapsed, if said time required for pressurization        is less than said moving time.

                5. A method of controlling a spot welding robot according to claim 4, further         comprising the steps of:

                Executing plural number of times of measurement of said elapsed time of step (a)   for the same gun;

                Finding a mean value of said actually measured values; and

                Storing said mean value into said memory of step (b) as a time required for              pressurization for said welding gun.

                6. A method of controlling a spot welding robot according to claim 4, wherein

                Said time required for pressurization to be stored into said memory of said robot      controller of step (b) is the number of processing periods obtained by dividing               said movement command to said robot by predetermined processing cycles.

                10. Specifications

                1.PAYLOAD

                                The load carrying capacity or pay load specification does not define the                 additional weight that the manipulator can carry above the weight of its end                 effector or tool.thus when designing an application,both the weight of the tool       and any part it may carry must be considered since together they constitute the            payload as seen by the robot.In addition this specification does not define the         shape of the gripper or payload.two grippers weighing the same may have       different inertias.the robot may be able to perfors satisfactorily using one               configuration but not the other.

                2.REPEATABILITY

                                It is the measure of the ability of a manipulator to return to a position in                space where it had been previously.it is measured by going to the same positon in             exactly the same way.(i.e. over the same path,with the same pay            load,speed,acceleration,temperature,etc) a number of times.since most      manipulators are designed to be slightly underdamped,so that they oscillate(in         damped manner) somewhat about the final position, it is necessary to wait for a             short period before repeatability is measured.

                In addition repeatability may be defined in three dimensional space or on a joint-    by-joint basis.

                3.Maximum tip speed:

                                The maximum tip speed ,no load is an attempt to define how fast the     manipulator can move.

                11. FEATURES OF S-900iB

FANUC ROBOT: S-900iB

                The FANUC S-900iB series of robots are engineered for precision, high- speed/high payload operation, user-friendly setup and maximum reliability.

                FEATURES OF S-900iB:

           1. Small robot footprint and reduced controller size conserve floor space.

       2. Slim arm and wrist assemblies minimize interference with system peripherals and allow operation in confined spaces.

       3. Many process attachment points make integration easier.

       4. Wrist design suitable for harsh environments.

       5. Multiple controller type and mounting capabilities.

       6.Process/application cables routed through the arm

                Industrial Applications: Spot Welding

 pnuc Robot Controllers: R-J3iB

                The Fanuc R-J3iB uses surface mounting and 3D packaging to reduce       components and increase reliability. Multi-processor architecture permits                 concurrent operations, reduces program execution times and increases path             accuracy. The quick change servo amplifier improves maintainability and controller uptime.

                The Fanuc R-J3iB features distributed and network I/O options reduce system          and integration costs and simplify troubleshooting. Auxiliary axes options can              support up to five separate motion groups, each with its own control program and simple kinematic models. The multi-tasking operating system allows execution of       several concurrent user programs. The advanced storage, communications and        networking capabilities include built-in Ethernet and PCMCIA interfaces.

                The Fanuc RJ3iB also features collision detection to minimize potential damage     to the robot or end-of-arm tooling.

12. FEATURES OF LR MATE 200iC

                                                           LR Mate 200iC

                LR Mate 200iC is 6 axes mini robot whose arm is similar to human arm length.

                FEATURES OF LR MATE 200iC:

·    The arm section area is minimized to 43% from previous model. The slim arm enables easy operation in narrow space.

·    The lightest mechanical unit makes installation in the machine and upside-down mounting easy.

·    High rigidity arm and the most advanced servo technology ebable smooth motion without vibration in high speed operation.

·    Wrist load capacity is enhanced extremely. It makes efficiency to increase by handling plural work pieces.

·    Enclosed controller of R-30iA Mate enables reliable operation under factory environment with dust and oil mist.

·    Various intelligent functions are available, such as "robot link" that synchronizes plural robots operation, "soft float" that enables the hand to follow the work piece and "collision detection" that minimizes damage by interference to peripheral devices.

·    Advanced intelligent functions are available as an option, such as iRVision (integrated vision) and part insertion by force sensor.

·    The payload at the robot's wrist has been significantly improved, which is an important feature in material handling. Compared to the previous model, the new robot's wrist moment has been improved by 155% to allow workpieces to be better supported, and its wrist inertia has been enhanced by 200% to allow faster workpiece motion.

·    A 152% improvement in its cumulative 6 axes motion speed over the former model brings about the best motion performance in its class.

·    A 39% reduction in its arm diameter enables the robot to move without interference in a narrow space. The resulting minimum turning radius of the robot body expands the effective motion range, and improves horizontal motion range by 136% over the former model.

·    The mechanical unit weighs 27kg, 60% lighter than the former model, and the lightest weight in its class. This light and compact mechanical unit enables the robot to be installed inside a machine or to be easily mounted on the ceiling.

·    Although the robot's weight has greatly been reduced, the rigidity, essential for quick motion, has also been increased. The slim and highly rigid arm in combination with the FANUC's latest servo technology realizes the best motion performance in its class while eliminating vibration.

·    The dust and dripproof option (IP67) can be added to protect the robot from water infiltration at a depth of 1 meter for 30 minutes. Not only the mechanical unit but also the robot controller are sealed and are equipped with a dustproof mechanism to prevent the outside air from infiltrating the robot controller, enabling the robot to be used in a severe factory environment with abundant oil mist and machining dust. FANUC will also offer an even more powerful environment resistant model for washing and other severe applications.

·    The robot's compact controller R-30iA Mate offers a wide variety of intelligent capabilities which include: Robot Link to coordinate motion of multiple robots, Soft Float for the robot to trace ejector motion of die cast retrieval, and Collision Detection to minimize damage caused by interference between robot arm or hand and peripheral equipment. The robot also features sophisticated intelligent capabilities, including built-in iRVision, bin-picking and parts insertion by force sensor.

Load/Unload from a lathe                                                 Load/Unload from a ROBODRILL

13.           FEATURES OF R-2000iB

                                       FANUC Robot R-2000iB and R-J3iC (*) Controller

·    The R-2000iB is fully compatible with the R-2000iA. It is controlled by the latest robot controller, the R-J3iC (*), and offers many enhancements in its intelligent capabilities and motion performance.

·    The R-2000iB features the identical specifications of its predecessor, the R-2000iA, in motion range, installation interface, and operability of its equipment mounting surface. In addition, its programs are fully compatible with those of the R-2000iA, making replacement of the R-2000iA easy and efficient.

·    The R-2000iB series, like the R-2000iA, offers a wide range of  models, including the standard 165kg payload model, a high capacity payload model, and a rack-mounting model. This full product line-up lets customers choose the robots best suited to their applications.

The latest robot controller R-J3iC (*) features:

·    The R-2000iB is controlled by the R-J3iC (*) controller which is based on the latest Series 30i CNC and integrates the latest control technologies in the enhanced hardware to strengthen the robot’s basic performance and include an abundant array of intelligent capabilities.

·    Its robot link function can link up to 10 robots by communicating the robot’s position information among them to provide seamless coordinated operation.

·    The R-J3iC (*) controller includes integrated vision capability which helps to provide a simple and compact robot system.

·    When an alarm is generated, the iPendant displays maintenance information to perform prompt and quick maintenance.

                14.           FEATURES OF M-710iC:

                                                  FANUC Robot M-710iC

Four models are available to meet a variety of application :

1.FANUC Robot M-710iC/50,70

                This model has a longest reach in the medium payload handling robot. The wrist     capacity is enhanced drastically, and the strong wrist enables to handle large              panel.

§    M-710iC/50 : Payload capacity 50kg

§    M-710iC/70 : Payload capacity 70kg

 2.FANUC Robot M-710iC/50S

                This model has a compact body without reducing strong wrist  capacity. It's            suitable i0n narrow area operation. (Payload capacity 50kg)

3.FANUC Robot M710iC/20L
                Long reach and high motion performance are suitable for various applications,       such as handling, sealing and arc welding. (payload capacity 20kg)

·       The robot can be used safely by putiing full cover in variety application, such as variety load / unload for machined parts, deburring and die cast handling, because it has IP67-equivalent resistance to environmental conditions (dust and dips).

·       M-710iC can be installed on the floor, upside-down or inclined at any angle.

·       Latest intelligent functions can be applied using vision sensor or force sensor.

15.           Classification of Robots on the                                                    basis of Payload

16. CONCLUSION:

THE BENEFITS OF AUTOMATED SPOT WELDING INCLUDE:

Ø        Consistency of quality welds

Ø        Repeatability

Ø        Reduction of costs

Ø        Increase your return on investment (ROI)

Well-engineered welding systems include benefits that range from improved weld quality to decreased variable labor costs. The foremost advantages are:

Ø        Improved Weld Quality: Mechanized welding improves weld integrity and repeatability.

Ø        Increased Output/Volume: Production weld speeds are set by the machine at a reasonable percentage of maximum. With minimized part set up time, and higher weld speeds increased output will occur.

Ø        Decreased Scrap/Rework: Automating the torch/part motions and part placement minimizes the error potential.

Ø        Decreased Variable Labor Costs: Relying on human welders dramatically increases a manufacturer's labor costs. A Semi-Automatic system will normally have at least twice the output of a skilled welder. A fully automatic system with sufficient stations can run at four times the pace of semi-automatic system or at eight times the pace of a skilled welder.

Future of Robotic Welding

As of 2005, the robotic arm business is approaching a mature state, where they can provide enough speed, accuracy and ease of use for most of the applications. Vision guidance (aka machine vision) is bringing a lot of flexibility to robotic cells. So we have the arm and the eye, but the part that still has poor flexibility is the hand: the end effector attached to a robot is often a simple pneumatic, 2-position wrench. This doesn't allow the robotic cell to easily handle different parts, in different orientations.

Hand-in-hand with increasing off-line programmed applications, robot calibration is becoming more and more important in order to guarantee a good positioning accuracy.

Other developments include downsizing industrial arms for consumer applications (micro-robotic arms), manufacture of domestic robots and using industrial arms in combination with more intelligent automated guided vehicles (AGVs) to make the automation chain more flexible between pick-up and drop-off.

Prices of robots will vary with the features, but are usually from 12,000 USD for an entry-level model, and as much as 100,000 or more for a heavy-duty , long-reach robot.

17.           Bibliography

1.        ROBOTIC ENGINEERING (An integrated approach)-Richard.D.Klafter                                                                         Tomson.A.Chmielewski, Michael Negin.

2.        www.roboticsonline.com

3.        www.fanuc.com

4.        www.kuka.com

5.        www.google.com