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Pneumatic press with task oriented add-on facility solves pressing problem

The required unit volumes establish limits on automation needs for many fabrication and assembly tasks. The supplier's expertise is required to nevertheless attain the objective of cost reduction, work simplification and process reliability. When the supplier can rely on proven type series and add-on facilities, and has the ability to provide task oriented solutions based on extensive know-how, the required tasks can be solved  effectively and affordably.

 

Of the hydraulic presses and forming plants up to 50 000 kN have earned Dunkes from Kirchheim/Teck an outstanding worldwide reputation as a competent supplier of machinery and workpiece-specific production plants. In contrast, pneumatic presses are lesser-known, since the applications are typically less spectacular. However, as an important production segment in many operations, these have been a cost-effective alternative for the lower force range of the hydraulic press product line.

 

Standard pneumatic presses are available with press forces from 5 to 80 kN in various configurations, ranging from table designs to single column presses with adjustable table. Control versions, such as two-handed or joystick controls, light curtain triggers, manually adjustable depth stop for accurately reproducible stroke depth, as well as foot switches on secured tools, permit the task-oriented configuration of the respective presses.

 

This product variety within the pneumatic press type series provided a spindle manufacturer for the textile industry the basis to economically automate pressing operations of shafts into housing castings, and to correspondingly organize this in accordance with quality assurance specifications. The coated shafts needed to be pressed into the housing with the conical shaft end at high repeatability in such a manner that a loadbearing interference fit was created, while also ensuring that the housing bore was not damaged or even cracked as a result of the pressure. The key functional and quality criteria therefore included the highly sensitive  insertion pressing of the shafts, and the continuous measurement and documentation of the press force as a function of the insertion depth.

 

For this task, Dunkes recommended a standard press of type DZ 2 / VZ 3 in a table configuration with 30 kN of press force. in order to  control the pressing process in the desired form, the ram was equipped with a ring load cell with DMS technology. The ring load cell facilitates programming and measuring of measuring locations within the stroke via the machine control. The influence of friction forces, such as those of the piston seal, is excluded. If the increase of the press force on the manually inserted shaft is within the specified tolerance envelope, the control registers the part as good, releasing it for removal from the pallet. When the press forces are outside of the tolerance envelope, the control prevents the automatic switching of the ram to retract stroke. The operator is required to intervene by removing the shaft and releasing the press stroke for the next workpiece by actuating the fault button.

 

The controlled insertion pressing of the shafts at a manual workstation provides the user with all relevant data for quality assurance. The previous insertion pressing process depended on the individual skill of the employee, and has now been replaced by a nearly defect-free process that makes a significant contribution toward a reproducible process sequence for a process capable housing assembly. Since all of this was made possible with a standard machine with adapted add-on facilities, the user was able to  incorporate all benefits of the compelling price/performance ratio soon after production startup – including the short delivery time of only 12 weeks.

Pneumatic table press of type DZ 2 / VZ 3 with ring load cell on the ram to press shafts into housing castings (workspace without shaft pallet).
The values determined by the electronic force/distance monitor are displayed and classified as pass/fail parts.