Disain Sistem Kontrol Mesin Auto Washer Feeder Berbasis Kendali Plc Untuk Perakitan Bvc (Base Valve Complete) Pada Pembuatan Shock Absorber

Line sub assembly merupakan line di mana komponen bagian dalam dari shock absorber dirakit. Salah satu proses pada line sub assembly adalah proses perakitan Base Valve Complete (BVC). BVC merupakan salah satu komponen penting pada shock absorber yang berfungsi mengatur sirkulasi fluida pada saat shock absorber mengalami kompresi. BVC untuk model shock absorber ini terdiri dari guide, non-return spring, non-return valve, base valve case, leaf valve, shim, dan valve stopper. Leaf valve merupakan plat tipis berbentuk lingkaran dengan ketebalan 0.1-0.2 mm. Permasalahan pada proses perakitan BVC adalah operator kesulitan dalam memisahkan leaf valve sesuai dengan jumlah yang ditentukan. Kesalahan jumlah leaf valve yang dirakit akan menyebabkan BVC menjadi reject. Solusi dari permasalahan tersebut adalah dengan dibuat mesin auto washer feeder. Mesin ini berfungsi untuk mengeluarkan leaf valve sesuai dengan jumlah yang ditentukan. Kontrol pada mesin auto washer feeder terdiri dari perangkat input, perangkat proses, dan perangkat output. Perangkat input terdiri dari push button, selector switch, toogle switch, emergency switch, photoelectric sensor, proximity sensor, reed switch. Perangkat proses menggunakan PLC Omron CJ1M-CPU11. Perangkat output yang digunakan adalah lampu indikator, silinder pneumatik, dan cool muscle ac servo motor. Hasil yang diperoleh dari pembuatan mesin ini adalah operator menjadi lebih mudah dalam melakukan perakitan leaf valve, berkurangnya waktu perakitan leaf valve dari 81 detik menjadi 50.6 detik, dan berkurangnya jumlah BVC yang reject dari 8 pcs per minggu menjadi 0 pcs per minggu

Experimental Investigation of the Dynamic Performances of a Miniature Soft Magneto-Rheological Shock Absorber

In the proposed work, the dynamic performances of a miniature soft Magneto-Rheological (MR) shock absorber are analyzed. The final application for which the damper has been designed and in which it will be embedded is a variable stiffness insole for patients with foot neuropathy and undergoing plantar ulcerations. Considering that the common design methodology used to dimension MR devices merely defines the maximum ratings of the sustainable efforts (i.e. maximum sustainable load for MR dampers, pressure drop for MR valves and braking torque for MR brakes or clutches), the relevance of their dynamics involved (respectively the impact velocity of the loading body for shock absorbers, the imposed flow rate and the rotating speed for MR valves and brakes) is often neglected in the dimensioning phase although it may assume a fundamental relevance. The understanding of the dynamic behavior of MR devices become even more important if these latter are part of a element or a more complex system in which all the elements differently affect its final behavior. With this respect, test sessions are conducted to experimentally evaluate the contribution that the different elements composing the damper in order have on the overall performances of the final systems. © 2016 IEEE

Design, Modelling and Sensing Possibilities of Magneto-Rheological Based Devices

This thesis has been put in place during the development of an innovative medical device which consists in an intelligent footwear for foot plantar pressure redistribution in diabetic patients. In fact, despite the several sophisticated techniques developed in the last twenty years, diabetes remains one of the first causes of non-traumatic lower limb amputation worldwide. This is mainly due to the combination of peripheral neuropathy, which determines the loss of pain sensation in the lower extremities, and high plantar pressures, both recurrent among diabetic patients. The target application imposes severe constraints for what concerns the system requirements because of the high plantar pressure magnitude and dynamics achieved by diabetic people during walking. Furthermore, the need to maintain the offloading system portable requires at the same time a high level of miniaturisation and a reduced power consumption. Within a so challenging scenario, a regulating principle relying on Magneto-Rheological (MR) fluids, may represent a good solution. In fact, MR-based systems offer as main and common advantages high sustainable loads, high dynamic ranges of operation, low complexity, high reliability and low power consumption. MR fluids are a particular group of smart materials whose rheological properties (mainly the fluid internal yield stress which in turn determines the apparent viscosity of the fluid itself) can be controlled by and external magnetic field. With increasing levels of exciting field higher values of viscosity can be obtained, with the consequent possibility to control the material transition from the liquid to the semi-solid state. The research work presented in this thesis focuses on MR valves, the core element of the offloading system conceived. Nevertheless, the analysis has been conducted in order to be as broad as possible and most of the concepts presented can be extended to all MR-based devices. The development of an enhanced magnetic equivalent circuit to take into account relevant fringing and leakage phenomena is firstly addressed. High accuracy, flexibility and computational efficiency characterise the proposed approach which can be generalised to any axisymmetric structure. Analytical models are developed to describe three MR valves configurations and the analysis steps followed can be used as guidelines to define a design methodology. A dimensioning routine is implemented to shape the valves structures in order to fulfil some imposed design requirements and/or compare the different valves performances. A qualitatively consistent attempt for the dynamic modelling of MR valves is presented through considerations on energy exchanges between the different physical domains involved. This analysis underlined that MR-based systems behave like transducers and their sensing possibilities are demonstrated experimentally. Finally, all the contents addressed contribute to the conception and realisation of a miniature MR soft shock absorber, the basic constitutive element of the variable stiffness sole conceived. The research activities and the related results presented in this thesis do not pretend to definitely clarify and fix all points still open to question. The aim of this work is rather to provide some further elements and concepts to improve the design and modelling of MR- based devices