Anđela Perović

Gears are fundamental machine elements used in various industries due to their durability, ability to transmit high torques, and high precision. Modern demands for gear manufacturing involve improving production methods in order to achieve greater efficiency while maintaining the prescribed tolerances. The focus of this study is on the fast, simple, and cost-effective manufacturing of gears and the geometric analysis of gears produced in such a way. For the purpose of this research, six pairs of cylindrical spur gears with straight teeth and involute profiles were fabricated. The gears were manufactured by laser cutting on a BODOR C6 machine, using low-alloy structural steel grade S355. After production, the gears were measured using a TESA Micro-Hite coordinate measuring machine, supported by PC-DMIS Gear software, in accordance with ISO 1328-1. The measured parameters were analyzed, identifying the potential applicability of laser cutting as a viable gear production method. In conclusion, recommendations for the use of such gears are provided. Further research will include the investigation of functional parameters of laser-cut gears, such as efficiency, noise, vibration, and more.

Planetary gear trains represent a special type of gear transmission whose element motion resembles the movement of planets around the Sun. Thanks to their compact design and the ability to achieve high transmission ratios with a relatively low total mass, they have found application in various fields of mechanical engineering. The basic planetary gear train (PGT) consists of two central gears (one with external teeth and the other with internal teeth), planet gears, and a carrier on which the planets are mounted. By connecting the appropriate elements to the input and output shafts, as well as by fixing certain components, different configurations or planetary gear train schemes can be obtained. This is described in the literature [1] and [2]. By adding gears and carriers to the structure of a simple planetary gear train, complex planetary gear trains are formed. Their advantage over simple ones lies in achieving a greater number of different transmission ratios. This has defined the wide application of PGT in automatic transmissions of various passenger and heavy-duty vehicles, as well as buses and construction machinery. To determine the transmission ratios, or the speeds of a multi-stage planetary gear train, it is necessary to understand the kinematics of the coupling between its elements. Considering the complexity of the motion, this represents a very challenging task. In books [1, 2], the most commonly used methods for solving the kinematics of PGT are presented.

Headless screws are commonly used fasteners in mechanical engineering, especially in applications where the screw must be flush with the surface it secures. In real working conditions, this type of screw is often exposed to axial forces, which may result from tightening or from external loads. Therefore, it is important to understand how axial force affects a headless screw connection in order to ensure a reliable and strong joint. Monitoring the axial force, which may be either tensile or compressive, is a key factor in maintaining joint safety and preventing plastic deformation. Recent studies have explored various nondestructive methods for determining axial force in screws. One such method is the ultrasonic technique based on the acoustoelastic effect, where the screw is divided into specific zones and the measurement error is typically below 10%. By introducing corrections to the clamping length and using suitable sensors, this error can be reduced to below 3%. In addition, advanced ultrasonic technologies allow for more accurate measurements by eliminating errors caused by poor sensor contact with the material. On the other hand, experimental methods are used as a complement, as they are performed under actual load conditions and take into account factors such as friction and microslip. The aim of this paper is to experimentally determine the axial force occurring in headless screws used to connect the outer and inner parts of a mechanical joint. The behavior of the screws under compressive load will be analyzed, and the results will contribute to a better understanding of the mechanical performance of headless screw connections. Future research will focus on modifying screw parameters in order to examine whether the length and diameter of the screw affect its strength and behavior under load. In addition, the influence of repeated (cyclic) loading on headless screws will also be considered

Cylindrical spur gears remain widely used in mechanical systems due to their simplicity and effectiveness, despite being a long-established component in engineering. While many aspects of spur gear design, analysis, and application have been thoroughly studied during decades, recent research trends have shifted toward optimizing manufacturing efficiency and reducing production costs. This paper presents the preparation of laser-cut spur gears for the purpose of evaluating their power transmission efficiency. The gears were produced using laser cutting technology, which offers potential advantages in terms of production speed and cost-effectiveness compared to conventional manufacturing methods. The experimental evaluation is planned to be conducted using the GUNT AT200 test rig, where the gears will be mounted on test gearboxes. Multiple gear pairs with identical center distances will be examined under controlled conditions to assess their mechanical efficiency. The primary objective is to determine whether laser-cut gears, despite potential limitations in precision and surface finish, can achieve acceptable performance for practical applications, particularly in prototyping and low-load scenarios.