DETERMINING THE COEFFICIENT OF FRICTION OF WOOD-BASED MATERALS FOR FURNITURE PANELS IN THE ASPECT OF MODELLING THEIR SHREDDING PROCESS

In order to improve the power selection of the drive unit for the shredding machines,theauthors determine the values of friction coefficients used in the cutting force models. These values consider the friction between steel and such wood-based materials as chipboard, MDF and OSB. The tests concern laminated and non-laminated external surfaces and surfaces subjected to cutting processes. The value of the coefficient of friction for the tested materials is in the range: for the static coefficient of friction 0.77-0.33, and for the kinetic coefficient of friction 0.68-0.25. The highest values of the static and kinematic coefficient of friction were recorded for MDF (non-laminated external surface) and they were equal respectively: 0.77 and 0.68. In turn, thesmallest values of the discussed coefficients were recorded for chipboard (laminated external wood-base surface), which were at the level of 0.33 and 0.25, resp.

Distributed variable stiffness joint assist mechanism based on laminated structure

Exoskeleton technology is more and more widely used in military, human rehabilitation, and other fields, but exoskeleton assisting mechanisms have problems such as high quality, concentrated driving sources, and poor flexibility. This article proposes a distributed variable stiffness joint power-assisted mechanism based on a laminated structure, which uses a giant magnetostrictive material as the driving source and the variable stiffness source of the structure. The distributed driving is realized by multiple driving units connected in series and parallel. Firstly, the drive unit stiffness matrix is deduced, and the expression equations of the cascaded total stiffness matrix of the drive module are obtained. After the simulation study, the curve of the stiffness of a single drive unit with a magnetic field and the stiffness of multiple drive units connected in series and parallel are in the absence of the magnetic field. The change curve of the stiffness of the booster module with the number of drive units under the excitation and saturation magnetic field excitation conditions is to achieve the effect of dynamically controlling the structural stiffness of the drive unit by controlling the size of the magnetic field and to obtain a general formula through data fitting. The number of drive units required under a fixed magnetic field excitation can ensure that the error is within 5%. The research results lay the foundation for further analysis of the distributed variable stiffness joint assist technology.

Application of a Thermo-Hydrodynamic Model of a Viscous Torsional Vibration Damper to Determining Its Operating Temperature in a Steady State

The problem of damping torsional vibrations of the crankshaft of a multi-cylinder engine is very important from the point of view of the durability and operational reliability of the drive unit. Over the years, attempts have been made to eliminate these vibrations and the phenomena accompanying them using various methods. One of the methods that effectively increases the durability and reliability of the drive unit is the use of a torsional vibration damper. The torsional vibration damper is designed and selected individually for a given drive system. A well-selected damper reduces the amplitude of the torsional vibrations of the shaft in the entire operating speed range of the engine. This paper proposes a thermo-hydrodynamic model of a viscous torsional vibration damper that enables the determination of the correct operating temperature range of the damper. The input parameters for the model, in particular the angular velocities of the damper elements as well as the geometric and mass dimensions of the damper were determined on a test stand equipped with a six-cylinder diesel engine equipped with a factory torsional vibration damper. The damper surface operating temperatures used in model verification were measured with a laser pyrometer. The presented comparative analysis of the results obtained numerically (theoretically) and the results obtained experimentally allow us to conclude that the proposed damper model gives an appropriate approximation to reality and can be used in the process of selecting a damper for the drive unit.

Analyzing mechanical vibrations of an aircraft opposed piston engine

The paper presents the results of the bench tests to measure mechanical vibrations of a new aircraft opposed piston engine with reciprocating pistons. The PLZ-100 engine is a three-cylinder, six-piston, two-shaft drive unit with a two-stroke diesel cycle. This type of engine is dedicated for powering light aircraft, e.g. autogyros. The tests were carried out on a test bench at the Lublin University of Technology. The engine was loaded with constant torque, for several fixed values of rotational speed of a crankshaft. The angle of the start of diesel injection was changed for each of the rotational speeds. The mechanical vibrations that accompanied the operation of this drive unit were recorded with three measurement transducers and a National Instruments conditioning system. Each of the transducers was mounted on a different axis of the engine. The signals were analyzed from their courses with the DIAdem software. The results were the courses of effective speed and vibration acceleration to conduct a vibration-acoustic evaluation of the PLZ-100, detect and prevent various types of defects or failures.

Investigation of the accuracy of the manipulator of the robotic complex constructed on the basis of cycloidal transmission

The object of research is modern robotic systems used in hotspots. In their arsenal, such mobile works are equipped with manipulators with high-precision hinges, which provide accurate positioning of the gripper (object of manipulation). Considering ground-based robotic complexes with a wheel or caterpillar base, the implementation of the process of manipulation on a stationary basis, a number of problem areas were identified that affect the accuracy of positioning. In the course of research and analysis of modern robotic complexes, their circuit and design of components and mechanisms that provide the necessary qualities and parameters. The problem of developing high-precision hinges is central to the creation of efficient ground-based robotic systems. The methodology of kinematic research of rotary hinges of the manipulator for the ground robotic complex is stated. The analysis of influence of deformations of material of impellers of not involute transfer on accuracy of positioning of a final subject is carried out. A kinetostatic analysis of the manipulator circuit was performed and the maximum moments acting in the hinged units on the drive unit were determined, which allowed to make a quantitative assessment using the Solidworks software package. The mathematical model of construction of transfer and definition of accuracy of a rotary knot for a ground robotic complex, with use of cycloidal transfer without intermediate rolling bodies is investigated and developed. Mathematical modeling and taking into account the features of mechanical processes occurring in the manipulator, allows to increase the technical level of robotic complexes. Ways of improvement are defined for maintenance of a progressive design of the manipulator that not only will satisfy necessary technical characteristics, but also will allow to simplify manufacturing technology. Modern technologies and materials (stereolithography, carbon fiber, superhard materials) make it possible to implement advanced designs of spatial drive systems. Therefore, work in this direction is relevant, as robotic mechanical complexes for special purposes are widely used when performing work in emergencies.

PERANCANGAN AUTOMATIC GUIDED VEHICLE (AGV) UNTUK MENUNJANG PROSES PEMBELAJARAN DI POLITEKNIK MANUFAKTUR ASTRA

Perkembangan teknologi di era masa kini sangatlah pesat. Hal ini ditandai dengan semakin luasnya kita mengakses informasi diseluruh dunia. Tidak hanya itu, dari sektor industri juga tidak luput dari perkembangan teknologi itu sendiri. Perkembangan teknologi manufakturing saat ini salah satunya material handling yang berfungsi untuk memindahkan barang dari satu tempat ke tempat lain yang bertujuaan untuk logistik maupun untuk porses produksi. Perkembangan dari material handling tersebut mengarah kepada autonomous system atau sistem yang berkerja secara otomatis. Salah satu realisasi dari hal tersebut adalah Automatic Guided Vehicle (AGV). Dalam rangka menunjang pengembangan pembelajaran sistem manufaktur di Politeknik Manufaktur Astra dibutuhkan protoipe AGV sebagai langkah awal untuk pengembangan sistem tersebut. Penelitian ini fokus pada pembuatan prototype AGV untuk menunjang praktek dengan obyek assembling berupa unit sepeda motor. AGV yang dirancang akan bekerja secara otomatis menggunakan dan prinsip line follower. Alur proses perancangan AGV menggunakan metode VDI 2222 dimulai dari tahap merencanakan, membuat konsep, merancang dan tahap akhir yaitu tahap penyelesaian. Hasil yang didapat dari perancangan yaitu rancangan dan simulasi perhitungan dari frame yang dapat mengangkut beban yang sudah ditentukan, drive unit menggunakan prinsip tricycle drive dengan tambahan 2 roda swivel yang berfungsi sebagai penyeimbang, spesifikasi komponen standar yang dibutuhkan di AGV dan rancangan akhir dari Automatic Guided Vehicle.

The Use of Short-Term Compressed Air Supercharging in a Combustion Engine with Spark Ignition

The powertrain is a very important subassembly in a car and is responsible not only for the automotive industry’s impact on the environment but also for the safety of people travelling by car and performing overtaking manoeuvres and joining traffic. In general, the powertrain is a combination of the drive unit and drive transmission, wherein the drive unit is responsible for the available driving force in the car’s wheels and for the car’s ability to accelerate when the throttle pedal is rapidly pressed at a constant gearbox ratio. The availability of the driving force reserve in the powertrain is the most important issue for the reason of safety of the people travelling by car. In the case of drive unit what they are of the combustion engines, the rapid pressing of the throttle pedal in the car acceleration process leads to a temporary deficiency in the driving force and in the powertrain’s output. The deficiency in the driving force has a negative impact on acceleration and driving comfort. In this paper, the authors assessed and analysed two different short-term compressed air supercharging systems for combustion engines with air supplied from a high-pressure tank. The analysis covered the response of the combustion engine with spark ignition to the gradual increase in pressure in the air-intake system. The assumption is that the applied short-term compressed air supercharging system could improve the driving force during the phase of the engine’s increasing crankshaft rotational speed. This helps to achieve the improved passenger car acceleration dynamics, depending on the supercharging method and throttle pedal exertion. When analysing the car’s acceleration dynamics, expressed by the shorter time of increasing the longitudinal speed from initial to final, it was possible to shorten the acceleration time. It is also possible to observe an improved driving force behaviour, especially during the first phase of acceleration.