Components from ACE in the universal screwdriver

In 2006, David Fuchs, founder of Metallatelier, and his team first succeeded in creating a special machine for a manufacturer of cleaning agents that provided unprecedented flexibility and reliability in the automated screwing of bottles. The Universal Capper 1.0 was born. Word of this design had spread in the industry that it had a unique screw cap assembly device that automated the secure capping of a wide range of cleaning agent bottles, including those with pump spray heads. When the new beta coronavirus Sars-CoV-2 broke out in 2020 and disinfectants could not be produced quickly enough, the company Bilgram Chemie asked Metallatelier whether a follow-up series could be ordered at short notice. While the aim of the invention in 2006 was to speed up handling and reduce the workload for operating personnel, the focus in 2020 was on increasing the speed of production. "On the other hand, the aim was to make the entire machine even more variable and at the same time faster to adapt to new closures and belt heights, because our new customer primarily wanted to fill small vials with hand disinfection on the three special machines," says David Fuchs, describing some of the new requirements.

More power through the use of high-tech components

To achieve these goals, the new design uses the basic operating principle of its predecessor: the bottles are held in place by two clamping jaws coated with ethylene-propylene-diene (monomer) rubber (EPDM) in the center under the screw mechanism. Four gripper rollers grip the cap and screw it tight until the defined torque is reached. Small shock absorbers are used not only to slow down the pneumatic slide, but also to determine the end position of the gripping mechanism by means of the damper position and thus adjust the machine to screw caps of different sizes. The slide does not usually move to the end position, but is stopped beforehand by two small shock absorbers positioned at the bottom. A small shock absorber at the top ensures that the carriage does not have to move to its end position every time, but is stopped as soon as the gripper rollers are open wide enough so that the screwed-on lid can be conveyed further in a time-saving manner.

Symmetrically positioned dampers

In addition to other innovations, new designs were required for braking the carriage in the end positions. While the predecessor model used ACE MC150EUMH small shock absorbers in the upper and lower end positions, David Fuchs and his team rethought the damping system in 2020: "While we are still working with the self-adjusting MC150EUMH type in the upper end position, we are now using two MC150EUM hydraulic dampers at the bottom. The difference is that the upper damper is dimensioned for larger effective masses of 8.6 to 86 kilograms, while the ones used at the bottom are suitable for mass forces of 0.9 to ten kilograms. The symmetrically positioned dampers offer the additional advantage that the slide does not bounce and tilt unchecked in the event of incorrect operation, power failure or other faults," says the owner of the metal workshop.

Detail of the ACE tube structural damper that acts as a stop damper for the protective cover mechanism. © Metal workshop

Protection by the latter damper would also be conceivable at the top. For space reasons, however, the other type is used on one side, leaving the other side free for an end position sensor. The carriage drive is another key component, explains David Fuchs. He points out how precisely the pneumatic unit works and thus hits the upper small shock absorber exactly vertically, so that its piston rod is optimally loaded and this machine element can make full use of its maximum service life of 25 million strokes. Precisely graduated hardness ranges and 20 Newton meters of energy absorption per stroke are further key values that reduce up to 34,000 Newton meters per hour in continuous operation, enabling the universal screwdriver 2.0 to be operated cycle after cycle under full load with the integrated fixed stop of the dampers.

Throttle cable springs relieve operating personnel and speed up changeover

Another focus of the optimization was to reduce changeover times when the special machine is set up for different bottle sizes. As the most important limiting factor for the staff when handling the capping unit is its weight, the team at the metal workshop was looking for an energy-saving and power-independent solution for adjusting the height and regulating the speed, and came up with industrial gas springs from ACE. A particular challenge for the integration of these components is the compact overall design.