Kyntronics’ high-speed/high-force dual cylinder actuator system optimizes complex clamp, press mode productivity.

Traditional clamp-and-press actuation applications present the challenge of having a rapid stroke at a low force, while requiring steep ramp-up to a high force for a short period. Achieving these demanding performance parameters typically means expensive oversizing of the hydraulic infrastructure to provide both high speed and high force.

Within this large machine footprint, delivering required position and force control presents complex motion and expense variables. In addition to having too many pieces in the equation, other factors include oversized and continuously running pumps, large hoses that often leak and require maintenance, and the energy consuming valves repeatedly turning on and off while transitioning from high speed to low speed.

To overcome the problem of oversizing components for applications that have a rapid stroke at low force with a load stroke at high force, motion control/actuation specialists Kyntronics have developed a high speed/high force (HSHF) all-in-one actuator. Combining a servo-based SMART hydraulic actuator (SHA), coupled with a high-speed actuator and a high-force pair of actuators – the HSHF delivers a cost-effective solution in a scalable, modular, power-on-demand machine platform.

The self-contained design doesn’t have hoses, eliminating expensive leaky infrastructure. The dual-cylinder configuration results in lower operating costs and better performance across various original equipment manufacturer (OEM) applications.

Clamp, press mode issues

The actuation technology uses hydraulics to overcome issues with existing clamp-and-press mode technologies including:

Clamp mode â€“ In this mode, rapid cycling times are needed while holding a force of 170,000 lbf/756kN going back and forth. This mode is predominant in injection and blow molding applications which require rapid back/forth position and hold, which puts significant pressure on the actuator.

Traditional systems include hydraulics that feature check valves that lock in position. Requiring a large footprint with a large pump and huge hoses, this solution is noisy and expensive. Electromechanical is also another option, but requires large and expensive components including motors, gearboxes, and roller screws/ball screws. Applying loads at the same mechanical position, consistent metal-to-metal contact reduces component life.

Press application

– This mode is typically used for 20 ton to 80 ton presses that need to come down quickly and work within a small distance for a short time. This application is currently dominated by hydraulic systems with large power units, pumps, and hoses.

Actuator innovation

As an all-in-one solution, the HSHF’s multi-cylinder, drop-in design features a variable displacement pump, servo motor, servo drive/motion controller, and closed-loop position and force control, with precision position and pressure sensors.

The design eliminates oversizing, and solves issues associated with current options (no hoses, quieter operation, more connectivity) in a reliable small package, potentially saving 50% or more in equipment and operating costs.

A reduced machine footprint eliminates the hydraulic infrastructure and oversized elements. Since there is no huge cylinder or large pump waiting for the cycle to start, it only uses power on demand. HSHF uses minimal energy for the long stroke and proportional energy for the load stroke.

Ease-of-integration with machine control systems and versatile control is possible, as the HSHF actuator is compatible with Fieldbus, I/O (selectable indexes), and analog (0VDC to 10VDV or 4mA to 20mA).

Dual-cylinder design

The HSHF actuator’s approach to hydraulic cylinder design mechanically connects a high-speed cylinder to a larger, high-force dual cylinder.

The dual cylinder combines a larger (high-speed zone) cylinder and a slightly smaller (high-force zone) cylinder together with a piston that seals in the smaller cylinder and moves freely through the larger cylinder. The high-speed cylinder pulls the dual cylinder’s piston through the longer stroke, so oil flows freely around the piston, into the smaller cylinder (high-force zone), sealing the piston, allowing for press or clamp mode. Cylinders can be adjusted to various lengths.

With SMART actuation, the system knows the exact position where the piston enters the smaller high-force cylinder zone and creates a seal. As the smaller high-speed cylinder approaches the high-force zone, the system slows and combines the fluid flow to the high-speed cylinder and the high-force cylinder without stopping motion. The system continues to press forward to the desired location based on force or position. After completing operation, the high-speed cylinder retracts, pulling the piston back. The high-speed cylinder’s speed reduces cycle times with minimal flow, force, and heat, reducing overall energy consumption.

The HSHF actuator design offers rapid, controlled clamp mode and smooth press mode in transitioning from HS-to-HF cylinders – with accurate force and position control.

During press mode, maximum power is required for a short period of the cycle (slower speed with high force) – minimizing the motor and drive size along with heat.

During a clamp mode, minimum power is required to rapidly move the cylinder (extend/retract). During clamping, power is not required as the check valves in the HF cylinder lock the actuator in position and the HS cylinder is placed in float mode to prevent cylinder damage.