Self adjusting pneumatic cushioning system
Festo has developed a self adjusting pneumatic cushioning system, which is now available as a build to order option for the company's DSNU series round cylinder pneumatic actuators.
The new system employs patented air channel geometry said to provide phased venting of the cushioning air. The system automatically adapts its characteristics to suit the cylinder's prevailing load and speed conditions, to provide optimum end-position cushioning.
Festo is initially offering the system on its DSNU family of round cylinders. Models available with the new system span diameters from 16 to 63mm, with stroke lengths up to 500mm – and delivery is usually within 24 hours. The DSNU series of pneumatic actuators already offers users a choice of polymer or manually adjustable pneumatic (PPV) end position cushioning, for applications involving low and high impact energy levels, respectively.
The new self adjusting (PPS) cushioning is primarily intended for medium impact energy applications, involving loads up to about 5kg and speeds up to approximately 1metre/sec. PPS cushioning is also available on Festo's CRDSNU corrosion-resistant stainless steel round-line cylinders, which it says offers the additional benefit of cleaner lines for improved wash-down by eliminating any potential for dirt entrapment around a cushioning screw.
Because the exhaust flow of the pneumatic cushioning chamber changes over the damping stroke, Festo's PPS system works with most commonly permissible speed and mass combinations.
Festo says that there are a number of advantages of self-adjusting end-position cushioning. Manually adjusting the end-position damping of linear actuators is time consuming and can only be done effectively once the actuator is in situ and under operating load conditions. By then the automation supplier is invariably under pressure to complete the task as quickly as possible. It also frequently involves two people – one to operate the appropriate pneumatic valve, the other to adjust the actuator's damping characteristics.
As with all moving parts, access can be potentially hazardous, which means that safety considerations dictate that only experienced personnel should perform these adjustments. Actuators are often less than perfectly adjusted, with under-damping resulting in higher end-position impacts, higher noise levels and increased wear, or with over-damping resulting in increased machine cycle times.
Festo estimates that on average, the new PPS self-adjusting end-position cushioning system will help users shave five minutes off a cylinder's installation and set-up time. For a typical application, such as a package sorting system with around 60 cylinder-driven routing stations, this would result in savings of five man-hours.
Festo's PPS self-adjusting end-position cushioning provides a complete 'fit and forget' solution. Since it has no settings to change it is completely tamper-proof, and it offers a long, maintenance-free service life. Festo DSNU pneumatic cylinders equipped with the new PPS system are 100 percent interchangeable with the company's manually-adjustable DSN-PPV models.
