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Speed and precision pushed to the extreme
Before the advent of Industry 4.0 shifted the focus to small batches, large-scale mass production was the territory of choice for automation. This type of manufacturing has far from disappeared, quite the contrary! There are many instances where cycle time, repeatability, and reliability are critical. At the same time, technological advances have further raised the level of attainable productivity. A clear example of this is the application implemented by Martoglio Srl, in which custom machines and Yaskawa's Motoman GP robot work side by side at a rapid pace.
The protagonists
Founded in 1950 by the initiative of two brothers, Martoglio S.r.l. is today an engineering company specializing in the design and construction of special machines. The solutions that come to life at its headquarters in Chiusa di San Michele (TO) are generally the result of an activity that starts from the roots: when a Customer interfaces with Martoglio, in fact, he often brings only a pure production need, which the company analyzes to first define the best process to obtain the required result and then move on to the design and construction of the technical solutions necessary to make these processes possible.
This can be a monolithic carousel-type plant or assembly plant, or complete lines, as in the case of the latest solution developed for T.Erre, a Borghi Group company specializing in the production of rigid and flexible piping for the automotive industry. Air conditioning systems, turbo oil piping, engine cooling piping, air piping, EGR piping, and piping for plumbing systems: the types of pipes needed in the industry are many, and just as many in the T.ERRE portfolio. This, together with continuous investment in technological upgrading, has led the company to rank among the leaders in the industry and to become-directly or indirectly-a supplier to all major OEMs globally.
- Industries
- Automotive
- Applications
- Machine Tending
- Press Tending
- Bending
- Material Handling
- Products
- GP Series
Small pipes of great importance
The new line is aimed at the production of a new item, serial production of which will start in early 2023. It is a pair of tubes that is part of the DPF (diesel particulate filter) circuit, thanks to which it is possible to detect the pressure difference on the exhaust pipe of engines, to allow the engine control unit to constantly monitor the clogging level of the DPF filter and implement specific regeneration strategies.
The end result of the processing implemented on the line are shaped 8 x 1 diameter stainless steel tubes equipped with head ogive and rubber mounts. Each pair comprises two inhomogeneous tubes - a longer one equipped with 7 bends and a shorter one with 6 bends.
From coil to finished product
The line is more than 20 meters long and starts with a group of uncoilers, which are responsible for unwinding the raw tube from the coils and sending it to an initial straightening and cut-to-length station to obtain segments of the required dimensions.
This is followed by deburring, which is necessary to finish the cut areas, then the tubes go to two end forming stations, consisting of front-end presses operated with electric axes that go on to create the deformations for the hose carrier on one side and for the flat seal on the opposite side. The tubes are then sorted onto 3 vertical-axis tube benders that can dynamically handle both short and long tubes.
After bending, the pieces are picked up and deposited on a chain that carries them, submerged, into a submerged-bath ultrasonic washing machine. On leaving this washer, they are placed under a vision system for checks on the size of the nosepiece holder and flat seal, and finally they are sorted: the long ones into special collection bins, while the short ones are placed on a conveyor and conveyed off the line to be finished by manual welding of a plate.
Handling, robot task
To meet productivity requirements and make it possible for only two operators to handle the entire line, all handling between different stations on the line is done by Motoman Yaskawa robots. A GP7, chosen on the basis of its small footprint, feeds the deburring machine, which is located in a very small space, while four GP12s, characterized by a more extended reach, provide handling between successive stations. The robots are also the only finished commercial part of the line produced, while all other machines were built by Martoglio S.r.l.
"We have not encountered any particular difficulties from the robotics point of view," says Roberto Martoglio, the company's president and CEO. "Some time ago we decided to train some of our internal staff to program the robots, with the aim of providing the customer with a high level of service, both in the programming phase and in the after-sales phase. And I can safely say that once programmed properly, Yaskawa robots are a safety."
T.Erre already employs several Yaskawa robots in its production lines and is therefore familiar with the machine, but even if it were not, no particular problems would have arisen, both because of the ease of programming offered by the YRC1000 controller and because of the intended mode of production. "This is a line that was created to process only one type of product and will work on 3 shifts always the same product so once the program is written and perfected by the integrator, it will always be the same program that will be used," Martoglio further explains.
Productivity at the highest level
We are indeed faced with an application in which mass production is pushed to the highest level, with very tight cycle times and tight tolerance margins. In fact, the two basic requirements were that the line should be able to produce a finished pair of tubes every 20 seconds and that it should be able to work in three shifts for seven days a week, in order to produce a very high number of parts per year. Any increase, even a small increase, in the average cycle time then results in large changes in annual output. Therefore, the tube-bending activity-the most delicate and time-consuming-is carried out through three twin machines, all equipped with the necessary programs to handle both long and short tubes. It is the master PLC that decides how to route the individual parts and which machining operations to start for each station, so as to avoid slowdowns.
It goes without saying that in this situation, the choice of an anthropomorphic robot model was the only truly effective option. "Today it happens very often that Clients ask us to use cobots, both because it is a very hot and fashionable topic, and to fall within the parameters useful to take advantage of the benefits granted by the State. The cobot is a great invention but it is necessarily much slower. Certainly in applications of this kind, where cycle times are very tight and manipulations with many degrees of freedom are needed, the traditional anthropomorphic is still the ideal solution," Martoglio explains.
To meet the requirements, the robots will have to work at an average speed of about 80 percent of nominal speed, obviously without affecting machining accuracy. The bending tolerance between the start and end of the parts is within a few tenths of a mm, so the machines were created to be extremely precise, but any discrepancy in their feed could cause them to exceed the threshold limit. The Motoman GP series robots give excellent guarantees in this regard, thanks to a repeatability of ±0.01 mm according to ISO 9283. "We have a long experience with Yaskawa robots and have been able to experience that the repeatability stated by the manufacturer has always been very reliable," Martoglio concludes in this regard.
When fully operational, the new line will be an example of mass production of large batches of parts that is extremely fast, accurate and reliable.