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Pneumatic Seals
Published in Heinz K. Müller, Bernard S. Nau, Fluid Sealing Technology, 2019
Heinz K. Müller, Bernard S. Nau
Normally, reciprocating pneumatic actuators are pressurized to 6–7 bar, sometimes up to 16 bar. The sliding velocities are predominantly between 0.2 and 0.5 m/s, sometimes up to 2 m/s. In terms of sliding distance the expected service life is between 5,000 and 20,000 km. Figure 1 shows the main components of a pneumatic actuator: seals for rod and piston, a scraper seal, and cushion seals for end-of-stroke braking system. Bearings on rod and piston support any external side loads. Formerly it was normal to use the same type of seals for pneumatic actuators as for hydraulic equipment. In this chapter it will be shown why at least the contact zone of a pneumatic seal must be substantially different from that of a hydraulic seal.
Selection of Sensors, Transducers, and Actuators
Published in Wasim Ahmed Khan, Ghulam Abbas, Khalid Rahman, Ghulam Hussain, Cedric Aimal Edwin, Functional Reverse Engineering of Machine Tools, 2019
Memoon Sajid, Jahan Zeb Gul, Kyung Hyun Choi
A pneumatic actuator changes energy of compressed air at high pressure into either linear or rotary mechanical motion. In pneumatic actuator, small pressure change produces significant large forces. Pneumatic actuators are quick to start and stop because their pneumatic energy only needs to be stored in the forward direction; therefore they are highly desirable in robotics. These actuators operate using compressed air which makes them safe compared to other conventional actuators. These actuators are also cheaper and relatively more precise and capable of handling high force operation.
Introduction and Definitions
Published in Eugene I. Rivin, Stiffness and Damping in Mechanical Design, 1999
Pneumatic actuators are very popular because of their simplicity, their very beneficial economics, and the possibility of their being used in circumstances in which electrical systems can create a safety hazard. One of the important disadvantages of pneumatic actuators is their reduced stiffness and natural frequencies caused by compressibility of air.
Dynamic modeling of dielectric elastomer actuators based on thermodynamic theory
Published in Mechanics of Advanced Materials and Structures, 2022
Huai Xiao, Jundong Wu, Wenjun Ye, Yawu Wang
Conventional rigid robotics are made with the high stiffness materials such as the steel, aluminum and titanium as well as rigid actuators, which include the servo motors and hydraulic motors. These actuators can generate great driving force, but the flexibility of them are greatly reduced [2]. By contrast, soft robotics mainly utilize the soft materials as the actuators [8], which include the fluidic actuators and intelligent material actuators (electro-active polymer (EAP) [9], shape memory alloy (SMA) [10], liquid crystal elastomer [11] and so on). Typical fluidic actuation includes the pneumatic actuation and hydraulic actuation. In which, pneumatic actuators are the most commonly used the actuators with the advantages of light weight, low cost and environmentally benign [12]. In [13], a fiber-reinforced pneumatic soft actuator is designed, and the experiments were conducted to verify the rationality of the actuator. Hydraulic actuators can provide larger force than the pneumatic actuators, and they are also widely used in the soft robotics. Katzschmann et al. [14] designs a hydraulic soft robotic fish that can swim in the pool flexibly.
Development and evaluation of pneumatic actuators for pediatric upper extremity rehabilitation devices
Published in The Journal of The Textile Institute, 2021
Bai Li, Huantian Cao, Ben Greenspan, Michele A. Lobo
Actuators are devices that produce specific motions or actions when directed via input signals (Actuators, 2011). Pneumatic actuators are comprised of soft, air-proof materials and can provide substantial forces over relatively large areas (Li et al., 2019; Lobo et al., 2015; O’Neill et al., 2017; Simpson et al., 2017). In a few prior studies, pneumatic actuators have been developed as soft actuators to assist movement at the shoulder, with placement in different locations, such as near the axilla (Li et al., 2019; Lobo et al., 2015; O’Neill et al., 2017; Simpson et al., 2017), on the top of the upper limb (Natividad & Yeow, 2016), or around the upper limb (Natividad et al., 2018). There are two primary forms of pneumatic actuators: air muscles and inflatable bladders. Air muscles (e.g. McKibben artificial muscles) consist of an inner rubber cylinder layer constrained by an outer braided nylon layer. During inflation, the system functions such that its diameter increases and its length decreases, allowing it to “contract/shorten” like a muscle (Tsagarakis & Caldwell, 2003). An inflatable bladder or textile actuator is a fluid-impermeable bladder which contains a fluid-impermeable textile structure or a fluid-impermeable structure [e.g. a thermoplastic polyurethane (TPU) bladder] housed in the fabric pocket (Walsh et al., 2020). When actuated, the inflatable bladder can offer support to the body segment of the user.
Relationship between acoustic emission signal and loads on pneumatic cylinders
Published in Nondestructive Testing and Evaluation, 2020
Houssam Mahmoud, Pavel Mazal, Frantisek Vlasic
Pneumatic actuators are widely used in the automation field. A pneumatic actuator converts fluid energy into a straight line motion (linear actuators) or rotary motion. The energy efficiency considerations of pneumatic cylinders are very important. One main point regarding energy efficiency is the correct dimensioning of the cylinder [1]. During the piston movement in a cylinder, different factors such as temperature, external load, friction, acceleration, process resistances and pressure affect the speed of the piston, which in turn affects the overall performance of the cylinder [2]. The pneumatic cylinder system is driven in vertical with a load.