Understanding Welding Positioning Systems
Weld positioners can be mounted in any configuration. This enables large weldments, fabrications or assemblies to be rotated in a controlled way in order to present the optimum angle to a welder or operator for welding or other operation such as assembly.
Since weld positioners are most often oriented with the axis horizontal, or able to be swung to horizontal, the center of gravity of the part will be overhung from a fixture that holds it. Given enough mass and a long enough part, a tailstock trunnion or set of rollers may need to be added to support the weldment at the other end from the positioner in order to safely support the part. It’s important to note that the center of gravity and lever arm (design torque) can change as parts are welded on to make an assembly so you want to work with an experienced company to make sure that your complete application is taken into account.
Weld positioners may hold the weldment with a special fixture may be made in order to ease mounting and aligning parts and create a safe and reliable welding setup. Chuck tightness or fixtures are set or designed to allow for the thermal expansion that happens as the welding process is performed. The weight of the fixtures has to be taken into account when sizing a welding positioner both for weight and torque from overhang but also from inertia in order to be sure that the system will both perform efficiently and meet the intended design life.
Weld Positioners are used by welders, welding shops and production facilities to position and move weldments in order to:
Weld Positioner Options will Often Include:
There are a multitude of different types of rotary welding positioners. They come in all shapes and sizes depending on the application they are to be used in. Here are a couple of popular options.
The most basic type of rotary welding positioner is a rotary indexer. Rotary indexers are standard rotary welding positioners and often have the fewest moving parts and features. They are capable of operating in flat or horizontal positioning, with most being capable of switching between the two positions. Rotary indexers are used in many precise welding applications and have variable speed controls, including reversing rotation directions. They are often used for welding round objects, although any weldment that can benefit from being rotated to present the next weld to the welder can be more efficiently welded with these machines. If used on their own, they are most effective when working with parts with shorter lengths, or shorter overhangs. When working with longer parts, standard rotary indexers need assistance in supporting the parts due to leverage from the overhang.
For the most degrees of freedom available and therefore the best access to every area of the weldment, multi-axis indexers are the go-to tool for many companies looking to improve their welding productivity. Quality of welds is also often improved when using multi-axis indexers, as the increased access to every area of the part allows the welder or automated welder to move the minimal amount, even with non-symmetrical weldments.
Multi-axis indexers have many different variants, including indexers with one mounting position for weldments and multiple positions for several weldments. One of the most common kinds is a double trunnion setup, with a pair of headstocks and tailstocks arranged parallel to each other. This configuration is located on a large turntable that allows the entire configuration to rotate 180 degrees. This is useful when trying to increase productivity, as on one trunnion, a part can be loaded and unloaded while a part is being welded on the other trunnion. When this operation is complete, the positioner rotates 180 degrees and the process repeats itself. This allows for minimal time that the welder or loader spends waiting on the other, decreasing downtime and increasing production levels.
Standard dual headstock tailstock trunnion positioners utilize a high precision (less than 1 arc second) planetary gear system mounted in a vertical position complete with mounting plates. Headstock Tailstock Trunnion Sets are ideal for moving large masses with smaller units and minimizing your equipment’s footprint on the floor. All trunnion units can be ordered with standard or custom frames fully equipped with head and tailstock supports and one-piece base weldments.
There are several tools that work in tandem with rotary indexers, specifically when it comes to supporting larger or longer parts.
Rollers – Rollers are a common tool used when extra support is needed for large parts and can either be powered or idler-type. Powered rollers can roll a part to be welded on their own, however, they may not have the precision of positioning that a rotary indexer has to accurately position a part for an automated welding system. For this reason, idler rollers are far more commonly used with rotary weld positioners. They are best suited to supporting cylindrical weldments, especially pipes, as these are the weldments that would roll the most easily.
Tailstocks – For the biggest, heaviest parts, and parts that won’t roll as easily, tailstocks are often employed to assist rotary indexers. Tailstocks can support weldments of almost any shape, with a chuck similar to the rotary indexer’s that grips onto the opposite end of the weldments. They allow for maximum flexibility when lifting and rotating the largest and heaviest pieces and are often synchronized with the headstock in terms of height adjustment so that the weldment stays level when it is being rotated.
Of course cost is a factor when selecting any type of automation equipment. Your weld positioner partner should be able to offer extremely high precision, low backlash and zero backlash options at a competitive cost. It’s often advantageous to be able to purchase complete trunnion solutions that might include a heavy duty base frame, riser bases and fixed or custom lengths.
The best headstock tailstock trunnion weld positioner sets utilize a high precision zero back-lash cam operated rotary index table mounted in a vertical position complete with mounting plates. Moving large masses with smaller units maximizes the productivity from your available footprint and also saves cost upfront. Machines should be painted to meet industry standards including specialty paints for corrosive applications if required and completely sealed machine surfaces to eliminate intrusions.
Weld Positioners should have large through holes to run utilities to the tooling and fixtures, easy access to pipe and wire all components and standard models available to quickly initiate the design process.
Weld positioners can have custom controls and pre-programmed panels to create a more flexible automation system and can be paired with robotics to accelerate productivity. You should have a choice of robot manufacturers for your project. Systems integrators that have freedom to choose the robotics manufacturer can adapt to their customers requirements, minimizing design costs from project to project.
Meet Application Demands
Welding serves as an integral manufacturing function for automotive, aerospace, oil and gas, machinery, marine, solar and wind, and construction parts. Because the welded connection encounters load and stress over time, if the weld is poorly executed, it will not meet application demands and will ultimately fail. Failure of welded parts can lead to lawsuits and the loss of customers. Therefore, manufacturers must produce consistent high-quality welds to remain in business. But, what contributes to a good weld? This is your guide to how to improve part quality with welding positioners.
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