Automated grinding enhances sheet metal supply

As part of the global ThyssenKrupp Group, Dortmund-based ThyssenKrupp MetalServ is one of the world‘s largest logistics centres for the supply of stainless steel and alloys with over 15,000 tons of metal continuously stocked at a 130,000m² facility with a 50,000m² hall space.

General manager Marcus Raback, explains: "We make sure that around 11,500 different sheets and bars are in the programme to reach the ThyssenKrupp Schulte subsidiaries just in time. Besides the Metals Germany Network, the logistics centre in Dortmund supplies customers all over Europe."

Various machining operations to customer specifications are also part of the processing system at the logistics centre. These operations can be chamfering of thick plates, grinding sheets or cutting plates or tubes to size.
Shop floor manager Joaquin Canhoto comments: "We offer our customers laser, plasma and waterjet cutting.
We have excellent machinery in-house with two flatbed lasers, three plasma cutters, three sheet metal working machines, 12 bandsaws, one robot operated circular saw plus a 3D laser and waterjet cutter. For optimum storage we use three Kasto tower storage systems with 4,000 cassettes and this allows us to handle 2,500 positions daily that can be shipped overnight.”

One example is the upgrading of an automatic sheetmetal grinding line that was supplied by Lissmac, available in the UK from Surtech. The goal was to make this line suitable to grind and brush mid-size stainless sheets with a new belt grinding machine.

The line is laid out to grind sheets in various qualities. An overhead crane places a stack of sheets on a table which is moved into the line. An automatic vacuum stacker places one sheet on an in feed roller table. The in-feed roller table has sheet positioning rollers to ensure that the sheets enter the grinding machine accurately. A marbling machine is placed in the same line as the sheet grinder and this can work independent from the grinder.

An automatic coating machine follows the grinder after positioning the sheets on a roller track. A second stacking unit places the coated sheets onto a movable table and the overhead crane transports the pallet with the finished sheets towards the shipping area.

To give the 1,500mm wide sheet grinding line a performance boost, ThyssenKrupp MetalServ decided to invest in a new machine that would increase the productivity. When necessary, the line can run three shifts per day.

"Our goal was not only to have a reliable and highly productive grinder, but also to be assured of fast service when needed. That's why we chose a Lissmac SMD 926 profiLine grinding machine,” states Mr Canhoto.
The Lissmac SMD 926 profiLine grinder has a through feed width of 1,650mm, enough to process 1,500mm wide sheets. With standard sheet length of around 3m, the line is laid out to also process longer sheets. The Lissmac- dry working machine has two aggregates available. The first head is an abrasive wide belt for grinding the surface of the sheets after the burrs from the shear are removed. The abrasive belt head is followed by a round scotch brush to work either separately from the abrasive belt or in combination with the belt. The brush is placed in a cassette that makes changing the brush a simple task.

"The aim of this operation is to create an industrial surface finish,” explains Mr Canhoto. “It is the finish we achieve for a kitchen sink or refrigerator and it is imperative that the finish across the full width and length of the sheets is spotless and constant."

To achieve this the machine must be free of vibration when grinding or brushing and a special Sorbtec frame provides the solid foundation required. Sheets are fed through the machine by rubber covered heavy-duty rollers that clamp the sheets for maximum safety. The accurately set roller drive speed is another important feature for a high quality finish. Directly beneath the belt and brush heads, hardened steel rollers support the sheets during the operation. These rollers ensure a constant working pressure across the width of the sheet and are responsible for an even finish.

Depending on the customer's wishes, the Lissmac grinder offers various finishes. The finish can be influenced by the choice of heads and the speed and working pressure parameters. Abrasive belt speed lies between two and 10m/second and the feed speed is from two up to 18m/minute.

In order to create exact finishes to customer wishes, ThyssenKrupp MetalServ can feed the sheets at a certain speed through the machine and also change the type of finishing heads.

THYSSENKRUPP METALSERV
www.thyssenkrupp-metalserv.com

SURTECH
www.surtech.co.uk