This article presents an experimental studies of an innovative solution for a system of two pneumatic cylinders with a synchronizing element, loaded with a force of different values. The aim of the ...research was to obtain the speed characteristics of two piston rods of pneumatic cylinders with the use of a synchronizing element. A comparative analysis of received characteristics was conducted and the criterion of the possibility of applying the synchronizing MZ_SYNCH element was adopted. The element for synchronizing the movement of two piston rods of pneumatic cylinders was called MZ_SYNCH for short. On the basis of the research results it was concluded that the system of two pneumatic actuators with the synchronizing element MZ_SYNCH can be used in rehabilitation devices for passive exercise of lower limbs.
The pneumatic cylinder is influenced by many various factors at work, including the climate environment. The climatic environment consists of two characteristic factors as temperature (T) and ...relative humidity (RH), which change according to seasons and different geographical regions. Therefore, changing the climate characteristic factors will affect the friction characteristic of pneumatic cylinders when operating at different speeds. This article presents empirical research on the simultaneous effects of temperature and relative humidity of the environment with the humid tropical climate in Vietnam on the pneumatic cylinder's friction properties. According to experimental planning, the studies were conducted on industrial pneumatic cylinders with two input factors: the temperature of 15°C, 32°C and 49°C and relative humidity of 51%, 75% and 99%, with velocities of 30, 50 and 100 mm/s. The results show that the static friction force and dynamic friction decrease when T, RH increases, and the influence of air relative humidity on friction force is more significant than temperature. The experiment also gives an empirical regression equation on the relationship of friction in the pneumatic cylinder, depending on the two factors of temperature and relative humidity of the humid tropical climate in Vietnam with velocities of 30, 50 and 100 mm/s.
Experimental study of friction in pneumatic seals Azzi, Abdelhak; Maoui, Abdelghani; Fatu, Aurelian ...
Tribology international,
July 2019, 2019-07-00, 20190701, 2019-07, Letnik:
135
Journal Article
Recenzirano
Odprti dostop
Friction in the pneumatic cylinders is one of the most important factors impacting their performances and their reliability.
This paper proposes to experimentally study the influence of the different ...seal geometry used in pneumatic cylinders and the operating conditions on the friction behavior.
Experimental tests are conducted on industrial commercial pneumatic cylinders. In addition, piston and rod seals are tested separately to study the friction caused by each seal.
The results show that the effect of pneumatic pressure on the friction is greater than that of the velocity. The seal geometry has a significant effect on friction, which is magnified as the seal diameter increases. In addition, 90% of the friction in pneumatic cylinders is due to the piston seals.
•Friction force behavior of pneumatic seals lubricated by grease has been experimentally investigated.•Both of piston and rod seals are studied separately to determine their friction effects.•The influences of different parameters including (seal cross section, seal diameter and operating conditions) on the friction force of pneumatic seals are studied.•The results show that the friction force of pneumatic seals is significantly influenced by the different studied parameters with a strong interaction between their effects.•This work provides more visibility on the friction force behavior of pneumatic seals lubricated with grease and also on the influence of different operating parameters.
Metal roofs overtaken the conventional roofing system in the recent days due to its reliability, it can withstand over 100 years without any damage. The assembler provides 50 years of warranty ...because it has better stability. The fixing of sheets over prefixed frame is a tedious process at greater heights. Due to the slippery nature of the polished sheets, it is quite difficult to fix the sheets by manually at highest building roofs. Hence, automation in this process reduces the accidents and reduces the processing time. To overcome this problem, a system is proposed to automate the process to fixing the metal roofs in the building roofs, which must be designed in flexible manner to the operator. To design and fabricate a low cost automatic sheet fixing system, contemplations of economy of the system, flexibility, easy handling etc., should be analyzed. A machine is fabricated to automate the sheet fixing process with effective features were inbuilt like pneumatic cylinders for linear movement and drilling machine The system is provided with rollers to accommodate its movement above the sheets in the desirable path with the help of 5/3 DCV valve. In addition, the horizontal cylinders are also used for retraction and the drilling machine is fixed to drills the screw at the fixed positions and the process will be repeated for several times based on the inputs. The inputs for drill positions are given in the wireless console by the way drilling process is controlled automatically.
The low investment cost is one of the core competitiveness advantages of pneumatic power systems. With increasingly pressing intelligent manufacturing, it is meaningful to investigate the feasibility ...of implementing fault diagnoses of pneumatic systems with a minimal number of low-cost sensors. In this study, a typical pneumatic circuit with two parallel-installed cylinders is taken as an example. The pressure, flow rate, and exergy data collected from upstream sensors are used for diagnosing the leakage faults in two downstream cylinders with the help of different machine learning methods. The features of data are extracted with stacked auto-encoders. Gaussian process classifier, support vector machine, and k-nearest neighbor are used for classifying faults. The results show that it is feasible to detect and diagnose downstream multi-faults with one or two upstream sensors. In terms of the working conditions presented in this study, the average accuracy of diagnosis with exergy data is the highest, followed by flow-rate data and pressure data. The support vector machine performs the best among the three machine learning methods.
This paper demonstrates the relationship between acoustic emission (AE) method parameters and loaded pneumatic cylinders. The cylinders in our experiment were loaded gradually by different weights in ...a vertical direction. The effect of the defect occurs when the cylinder is loaded at the retreat and progress strokes. This defect affects the relationship between the applied load and the recorded signal of the sensors. The signals of the acoustic emission were recorded from the progress and retreat strokes and then analysed. The time delay is calculated between the digital input and the initiation of movement, and the time of the stroke. The energy and root mean square of the acoustic emission compare between the distinctive different responses in damaged and undamaged pneumatic cylinders, with and without loading. The energy and RMS were calculated for each cylinder with gradual loading. The results of the test showed approximate linear relationship between the RMS and loading. This paper is a continuation of a previous article and the extension of my work to find distinctive differences that determine whether the cylinder is damaged or undamaged.
Pneumatic cylinders are widely used in highly dynamic processes, such as handling and conveying tasks. They must work both reliably and accurately. The positioning accuracy suffers from the ...stick-slip effect due to strong adhesive forces during the seal contact and the associated high breakaway forces. To achieve smooth motion of the piston rod and increased position accuracy despite highly variable position dynamics, sliding friction and breakaway force must be reduced. This contribution presents a specially designed linear tribometer that has two types of control. Velocity control allows the investigation of sliding friction mechanisms. Friction force control allows investigation of the breakaway force. Due to its bearing type, the nearly disturbance-free detection of stick-slip transients and the dynamic contact behavior of the sliding friction force was possible. The reduction of the friction force was achieved by a superposition of the piston rod’s movement by longitudinal ultrasonic vibrations. This led to significant reductions in friction forces at the rubber/metal interface. In addition, the effects of ultrasonic frequency and vibration amplitude on the friction reduction were investigated. With regard to the breakaway force, significant success was achieved by the excitation. The force control made it possible to identify the characteristic movement of the sealing ring during a breakaway process.
Pneumatic cylinders are intended to be designed for high reliability and long lifetimes. Evaluating such designs through conventional life tests is difficult as the affordable test time is too short ...to generate a meaningful amount of failure data. In this paper, we design and implement an accelerated life test (ALT) for evaluating the reliability of pneumatic cylinders. From a detailed analysis of failed samples from field operation, the major failure mechanisms that affect the reliability of pneumatic cylinders are identified, e.g., wear and tear of sealing rings. For these failure mechanisms, temperature and frequency are found out to be the significant stresses of the pneumatic cylinders. A two-factor-four-level full-factor design of ALT is, then, performed to set up an ALT plan for the pneumatic cylinders. A total number of 95 samples are tested according to the ALT plan, and a mixed Arrhenius-inverse-power-law model is used to fit the test data and predict the reliability under normal operation conditions. In addition, a normal stress test of eight samples is performed to validate the reliability predicted by the ALT. The results show that using the proposed ALT, the reliability of the pneumatic cylinder can be predicted with satisfactory accuracy. It is also shown that the designed ALT plan requires only 38.77% of the testing effort of other conventional life tests.
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