energy
The facing slide of the
Scharmann DBF 630
machining centre allows
boring and OD turning to
be carried out;
concentricity and axial
accuracy of 5 to 6 µm can
be achieved.
Valves finish-machined in one clamping as machine idle times are reduced to almost zero
One-hit accuracy
ONE of the world’s leading manufacturers of safety valves, LESER, located in Northern Germany, has installed two
Scharmann DBF630 horizontal machining centres from Dörries Scharmann Technologie (DST) to machine large
valve bodies and their spring covers in a single set-up. A key benefit of the machines is the design of the headstock
and spindle, which allows turning, drilling, boring and milling operations to be carried out.
The quality of the valve seat sealing surfaces is a defining criterion for the performance of safety valves, used
widely in the petrochemical industry, so accurate machining of these features is paramount. Previously, however, six
or seven separate metalcutting operations on lathes and machining centres were required to manufacture the bodies,
which compromised accuracy owing to the need for repeated reclamping of the parts. The process was time
consuming due to frequent inter-machine handling and redatuming of the parts. It was also costly, created a lot of
work-in-progress and resulted in long machine idle times.
The ability to carry out all machining operations in one hit on the DBF630s solves all of these problems and
ensures that the specified concentricity and axial accuracy of between 5μm and 6μm is consistently achieved. Only if
a component needs machining on the sixth face does it have to be reclamped. The turning, drilling and milling head
sets the DBF 630 apart from other machining centres. The spindle head incorporates a CNC U-axis which allows
turning and facing operations to be performed in addition to prismatic metalcutting.
The U-axis slide adjusts the turning tool radially according to the turning diameter and depth of cut. During the
cutting process, the turning tool rotates around the axis of the cylindrical surface being machined at up to
1,200revs/min, with a maximum torque of 1,700Nm. Compensation weights integrated into the spindle head
automatically compensate for the imbalance which would otherwise occur during turning. For drilling and milling
with the 35 kW / 3,500revs/min spindle, tools are located in the centre of the facing slide.
LESER’s valve range comprises a total of seven product groups, with 38 types of safety valve produced in a wide
variety of materials and sizes. Automated delivery of fixtured parts from a Fastems pallet store to the two DBF630s,
and return of machined components into store, results in a flexible manufacturing system (FMS) that has reduced
non-cutting times to virtually zero, 24 hours a day. Workpieces weighing up to 600 kg can be supported on the twin
630 by 630mm pallets of each machining centre. LESER has now ordered a third Scharmann DBF 630 which will be
incorporated into the FMS to cope with increased demand. www.ds-technologie.de
Enquiry Number: 28
48 MWP march 2009
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