High-speed press for manufacturing complex components
Stamping small items like electronic components, watch parts and automotive connectors does not require high tonnage although progression tools, with increasing numbers of stages, are needed to mass produce more complex products and require accommodating in a long bed. The new Bruderer BSTA 200 high-speed press is aimed to fulfil this market need.
Until now, manufacturers have had to buy an unnecessarily large, powerful stamping press to get a bed of sufficient length to suit some multi-stage tools. The new press model from Bruderer combines 20 tonnes (200kN) punching force, at the low end of the Swiss manufacturers range, with a generous bolster plate area of either 590mm or 690mm by 426mm for loading the tools.
The press has new control and feed systems and is priced to reduce manufacturing costs in order to help the West to compete with the threat from Asia and Eastern Europe.
The standard machine has a fixed 15mm stroke, while greater versatility of operation is available if the user chooses one of two options, either two fixed strokes of 8mm or 25mm or an adjustable stroke in seven increments from 8 to 38mm. Ram adjustment over 40mm can be carried out while stamping is in progress to fine-tune the position of bottom dead centre. Stroke rate is up to 2,000 per minute.
As with all Bruderer presses, the rigid drive shaft is mounted transversely, transmitting its power to the ram via two con rods and a lever system with mass counterbalancing for stability at high speeds. Absence of any lateral forces means that it has been possible to place the ram guides at strip level, avoiding punch deflection due to eccentric loads in the die.
The mechanical drive from the main shaft to the rollers feeding the strip through the tool is the innovation with this latest press. Instead of a single, angled linkage, a right-angle arrangement is used that allows the cardan shaft to enter the mechanical feed unit vertically.
The advantage is that changeover of the feed from one side of the press to the other is much faster, as the unit does not have to be dismantled. Speed of set-up is assisted further by placing the encoders in the top mount instead of on the side of the feeder. It has the additional benefit of protecting the encoders from vibration and making them more accessible for servicing.
The standard mechanical roller feed unit for the BSTA 200 is the new BBV180, which features quick-change rollers and automatic strip thickness adjustment. Material up to 200mm wide may be fed and pitches up to 100mm are possible. A gripper feed unit may be used instead if the application dictates.
The BSV range of servo feeds is available to the 200kN press in two sizes; the BSV75/75T and BSV170 with the number representing maximum strip width. The former models may be used for tandem feeding of two strips through the tool simultaneously, or for wide material. Maximum strip thickness is 2 mm.
The servo feed unit is synchronised with the angle of the main drive shaft and interfaced with the control. It can be used to push or pull the strip through the tool. Both the upper and lower rollers are driven so that pressure is transmitted equally.
During punching, the rollers are able to clamp the strip without the need for clamping bars, avoiding the risk of marking the material. Maintenance is minimised by integrated lubrication and cooling. (All BSV servo feeds can be retrofitted to any model of Bruderer presses.)
High-speed stamping, forming including deep drawing, assembly and over-moulding all require high accuracy and repeatability. This is ensured by Bruderers’ new, PC-based, touch-screen BE control system, introduced for the latest 20 tonne presses.
Functions provided include memory of tool or die parameters to allow rapid set-up for repeat batches, stepless speed adjustment, servomotor controlled ram adjustment with integrated position encoder and manual feed length adjustment with digital display of values. The options include press force measurement, tool monitoring and real-time inspection of stamped components. Coil handling and other ancillary options are also available through Bruderer UK.
