Safety valve manufacturer Leser has installed two Scharmann DBF630 horizontal machining centres from DS Technologie (DST) to machine large valve bodies and spring covers in a single set-up.

 

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 metal cutting 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 tuming 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 five and six micron is consistently achieved.

 

Only if a component needs machining on the sixth face does it have to be reclamped.

 

The spindle head of the DBF630 incorporates a CNC U-axis, which allows turning and facing operations to be performed in addition to prismatic metal cutting.

 

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 1,200rev/min, with a maximum torque of 1,700Nm.

 

Compensation weights integrated into the spindle head automatically compensate for the imbalance that would otherwise occur during turning.

 

For drilling and milling with the 35kW, 3,500rev/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 600kg can be supported on the twin 630 x 630mm pallets of each machining centre.

 

Leser has now ordered a third Scharmann DBF630, which will be incorporated into the FMS to cope with increased demand.