Valk Welding has now delivered the first welding robot cell
To stay competitive many coach and bus manufacturers move their production to low-wage countries. VDL Bus Modules has taken a different approach by investing in automation, including welding robots, to keep the cost price down. Keeping as much production as possible in its own country is a policy of the VDL Group. Valk Welding has now delivered the first welding robot cell. As well as complete 2D frames, the welding robots will also be welding side, front and back panels. "This is the future", says a worker as he proudly shows the new welding robot cell to visitors.
Frank van Geel, CEO of VDL Bus Modules: "Bus production is what we call 'hand and head' production. Up until now everything was welded manually at VDL Bus Modules. There are many variants and customer-specific adjustments, and this is a small-volume setting. But cost engineering has of course been carefully considered throughout the engineering process. We have focused on how we can develop modules in such a way that they have the same dimensions and are therefore more suitable for welding robots. A start has now been made with welding robot automation by welding the 2D cross sections for the basic frames. Robotisation is a good
way of producing more cheaply in an expensive setting. Our aim is to reduce the cost price and keep production in our own country."
Preliminary process optimised
Peter de Weerd, plant manager at VDL Bus Modules, was initially sceptical about welding thin-walled tube sections with robots. "The tubes must be accurately fitted together: even with the smallest imperfection the weld will fall through the gap. Manual welding gives you more control of this. For that reason we started by optimising the preliminary process of sawing and drilling by investing in a saw machine. Valk Welding also helped us with programming the welding robot. With their support we've got off to a flying start and have the welding process with the robot completely under control.
Philosophy underlying the welding jigs
The 2D frame sections (cross sections) used to be welded manually on large welding jigs that were tilted manually. Peter de Weerd: "The jigs were developed as far back as 2 years ago with the aim of using them on a welding robot at a later date. The intersections of the tubular frame sections can therefore be reached on 2 sides, so that the robot can weld the product all around. Valk Welding has supplied a welding robot system with four jig supports, in which four welding jigs (two by two) are placed in positioners. We can use these 4 jigs for a total of 14 different products (cross sections). A Panasonic TL 1800 welding robot is used to make 1 set of 5 cross sections for each bus in each production run, without having to change the jigs. This eliminates all losses caused by temporary storage, transport, jig changes, etc.
Bart Oppenheim, responsible for the programming of the CNC machines at VDL Bus Modules, followed a basic course in robot welding and DTPS at Valk Welding in Alblasserdam together with 2 manual welders. Bart now
programs using DTPS from his PC at the office, and the 2 manual welders are responsible for operating the welding robot. For this purpose Valk Welding supplied the 3D simulation of the welding robot system in DTPS and VDL Bus Modules added the jigs and 2D cross sections to this from their own CAD system. Peter de Weerd: "After a three-week course we were able to work independently. Up until now we haven't needed to make a single service call.
One piece flow
The tubes are now delivered straight from the sawing line to the welding robot and positioned on the welding jigs to be welded by the welding robot. Once one side has been welded, the positioner turns the jig so that
the welding robot can weld the other side of the intersections. This makes one-piece flow production possible for each cross section. The cross sections are then assembled at an adjacent department into a complete frame, on which the entire bus is built. Frank van Geel: "We made a conscious decision to start by using the welding robotisation for the 2D cross sections because the level of complexity is low. By using the welding robot we are able not only to achieve cost savings, but also a consistent welding quality, which translates into cost control and quality management. That is a perfect fit for the high quality standard of the VDL Group."
VDL Bus Modules
VVDL Bus Modules produces modules for luxury coaches, double deckers, VIP coaches, regional public transport buses, and also carries out special projects. VDL Bus Modules is one of the 5 production locations of VDL Bus & Coach, an international company that concentrates on the development, production and sale of a broad range of touring cars, public transport buses and chassis. VDL Bus & Coach is a division of the VDL Group, an international industrial company comprising 87 operating companies throughout 19 countries and employing 10,500 people. The modules produced by VDL Bus Modules are sent to the production location VDL Bus Valkenswaard, where they are assembled on the production line. VDL Bus Modules and VDL Bus Valkenswaard together produce approximately 700 touring coaches a year. www.vdlbuscoach.com
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