Low batch/mixed production
Production in low batches calls for frequent change of tooling in the robot cell, and in most cases the set up time between batches has a negative impact on productivity and flexibility. To allow for production in low quantities Andon Robotics has developed a number of Flexible Welding Systems. Material transport to and from the robot cell is performed either by a conveyor system or by a handling robot.
Flexible Welding Systems features elimination of set up times, thus the robot is able to produce in low quantities – down to one off. The user obtains new competitive tools such as shorter lead times, flexibility, stock reduction and production direct towards customer order. Most of the users will also benefit from increased time utilization as the systems can produce during breaks, between and after shifts.
Production around the clock is made possible. All together result in drastic reduction of production costs, which improves the competitiveness.
Production is totally adapted to current market demand or order intake and is in particular of interest for sub contractors and companies with own production of components.
This system is designed for welding of products that can be placed on a pallet with dimension 4500mm long, 2500mm wide and for product height of 900mm.
There are two identical loading stations, each equipped with a one axis positioner that can be manually controlled for easy loading.
A stacker crane system is used for transport and storage of pallets with or without workpieces. Transport carriages are used for transport between stacker crane and loading stations as well as welding cells and unloading stations.
The welding cells are in this case built up aroúnd a one axis positioner for 5000kg load and two robot travelling columns.
Each column has three axes which makes it possible to cover the full size of pallet in any position. The positioners are equipped with automatic pallet locking mechanism and docking system for compressed air and electrical signals to the pallet.
Andon User Interface is used for control of all logistics in the system.
The system for low batch production is in this case designed for welding of small components that can be loaded onto pallets of Euro pallet size (1200x800mm). There are six pallets in the production loop, but more than 100 different fixtures, which are loaded to the pallets by means of quick connectors. This ensures that setup time between batches is zero.
The operator is in the loading station loading the fixture on the pallet with the different parts that belong to the specific pallet. The pallet is after that it has been loaded picked up by a transport carriage which will take it to a welding station.
The pallet will at the welding station be transferred over to the positioner, which in this case is of single axis type equpped with a station interchange for short set-up time.
There are two identical welding cells, and the pallet that has been loaded is transported to the first positioner which is free. All pallets are coded and a new robot program is loaded into the robot controller at the same time as the new pallet is presented to the robot.
The workpiece will after welding be transported back to the same station as where it was loaded.
It is also possible to use separate unloading station, depending on the type of material flow desired.
The positioner used in this case is for a total of 750 kg load, including workpiece, pallet and fixture. Other types of positioners can be used depending on type of production.
System for automatic welding of 77 different models of telescopic arms in mixed order. The arms are loaded in desired order on a chain conveyor for infeed to the system. A vision system is used to identify which type of arm that has been loaded. The fork carriage will then transport the arm to one of two welding stations.
Each welding station consists of an IRB4600 robot mounted in a gantry and a positioner with automatic adjustable holding fixture.
The fixture is automatically adjusted for the current arm and correct welding program is downloaded to the robot during the loading sequence. The welded arm is after completed welding transported to a buffer consisting of a chain conveyor.
Many different products and mixed production required 500 storage place to keep track of all different fixtures and to quickly get them in production when needed. The 3 × 1 meter palettes can hold one or more fixtures and can be loaded at nine different places and un-loaded three places. Overall, this means that 800 product variants can be handled in the system.
Welding is carried out in two identical stations where any of the 800 products can be produced directly against customer order. Regarding pure productivity, the two robots do the same job as 45 manual welders. Production in single units or volumes does not matter as the set up time between variants is eliminated, thus the remarkable productivity increase.
This station is used for welding of different types and sizes of buckets and tools for excavators.
Loading of pallet takes place on a roller conveyor outside the welding cell, as well as unloading of welded product. The station is built up around our three axes postioner of tyep IRBP2000SHR with automatic pallet locking, which is used for docking of pallet from and to roller conveyors.
The three positioner axes are also used during welding, which gives the best possible welding position and accessability to the welds for the IRB4600 robot.
Cabins for off road vehicles can be welded in many different ways depending on type and size. One common way is to weld the different sides as well as floor and roof as sub-components, which are then welded together. The other way is to tack weld all the parts together after which it is welded as one unit.
One thing in common for different cabins is that they need to be positioned in two axes to be able to reach the welds and also to get them in a good weld position.
Different types of robots can be used depending on accessiblity to the welds, which can be tested in RobotStudio simulation program.
The robot used in this case is however a wall mounted IRB1600 robot. The solution with a robot at the end of a column and boom type robot carrier makes it possible to move the robot inside the cabin to reach all the welds as well as all positions at the outside.
A roller conveyor system is used for the loading and unloading stations, as well as for the four buffer places. A transport carriage takes care of the transport of cabins between the different stations.
The control system makes it possible for the operator to choose in which order the different types of cabins shall be welded, unloaded etc. This gives a full flexibility for the production.
The system consists of four robot cells inside environment houses and a stacker crane system for handling and storage of pallets. The system is ideal for profitable low batch production of medium sized products.
One advantage with a stacker crane system for handling and storage of pallets is that it can serve both loading and unloading stations as well as different welding cells.
The pallets can be stored in a number of levels, depending on height in the workshop, and also on both sides of the travel track of the crane.
It can also be used for storage of pallets with fixtures that are not used at the moment and also for pallets loaded with workpieces that shall be welded or have been welded. It is in this way possible to have a certain amount of unmanned production.
There are in this case four identical welding cells, each consisting of a three axes positioner for 2000kg load and a standing robot.
The positioner is picking up the pallets from a short roller conveyor connected to the stacker crane and is after welding placing the pallet on a second roller conveyor. This gives a short buffer which means that the robot does not have to wait for the stacker crane to come with a new pallet.
Mixed production, short set-up times and short delivery times are very common demands on sub-suppliers. It is for this reason important to have a flexible robot station for low batch production where it is possible to cange production with short notice.
This system is for a producer of frames in thick material, why a three axes positioner is used.
The positioner is used as a material handler for in and out feed of pallets to the roller conveyors. The third axis at the bottom of the positioner is also used during welding to get a better access to welds and a better weld position.
The load capacity of the positioner is in this case 2000 kg.
The in and out feed conveyors can each store four pallets. Since the welding time for each workpiece is approximately one hour, this means that the in-feed conveyor can be loaded at the end of the shift, and allow for an additional four hours extra production. The operator then find the four pallets with welded workpieces when returning in the morning for the first shift.
Large products can also with advantage be produced in low batches. The welding cell can be built up by robot carriers and positioners described under customized cells and the handling system can be built up by roller conveyors and transport carriages, or a stacker crane system.
This Flexible Welding System is designed to handle 40 different products on pallets that can be stored on 77 places in the storage system.
The size of the pallets are in this application 3200mm × 1200mm.
The stacker crane is connected to the customers order handling system for full control of the production.
There are four identical welding cells at each end of the system, each consisting of a robot travelling column and a positioner for 5000 kg load, with automatic pallet locking systems.
In the centre of the system there are three identical stations for loading and unloading. Each station is built up around one axis positioner for 5000 kg load and a tranport carriage.
The positioners are equpped with a manual function for turning, in order to make loading and post treatment easier.