ANALYSIS OF CONTACT STRESSES AND SLIP IN POWER SHIFT GEARINGS USING MULTI -CRITERION OPTIMISATION

The work analysed contact stresses and slippage occurring in specific toothed pairs of two power shift gearings with eight ratios. The analysed gearings have ratios of identical values. Differences in contact stresses and slippage values within individual toothed pairs of both gearings (at same values of input torque and engine speed) result from the internal configuration of the kinematic chains created by the toothed gears within individual gear ratios. The analysis included 5 characteristic contact points within the tooth engagement area. They were selected analytically depending on geometrical parameters of gears that constitute the toothed pair. Using computer-assisted design works that employ multi-criterion optimisation, it is possible to minimize slippage and take reasonable advantage of the fatigue contact durability of the material that was used for producing the toothed gears.

Optimal design for a cylindrical gear with inclined teeth

Designing is an act of creation, which is a technical activity carried out for productive purpose, and which aims to provide all the data necessary for the implementation of correlated material and financial means, a theme or an idea in practice. Depending on the operating conditions of the machines and their technological destination, optimum reliability, maintainability and ergonomics must be ensured from the design stage. For some areas where toothed gears are used, such as the aerospace industry, the automotive construction etc., reduced gear mass (volume) can be an important parameter to become an optimization criterion. This paper aims to study the gearing mass and proposes to minimize this function. 𝑀𝑔𝑒𝑎𝑟𝑖𝑛𝑔 = 𝑉𝑔𝑒𝑎𝑟𝑖𝑛𝑔 ∙ 𝜌𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 → 𝑚𝑖𝑛

Structural-topological synthesis of space mechanisms with rods and wheels

Today, robots are increasingly present in the machine building industry, sometimes even in some sections to replace workers altogether, due to the high quality of their work, repetitive, without stopping or pausing, without any manufacturing and assembly scuffs. In this paper, one presents the mechanisms with bars and gears, which are planetary mechanisms for robot automation and mechatronics, structurally-topological. The gears and bars consist of at least one movable articulated bar and one of the cylindrical, tapered or hipoidal gears. Only gears with circular or straight toothed gears, in which the relative position of the rotation or translation axes does not change, shall be considered. The topological structure of the gears and gears is characterized by a kinematic chain with articulated bars and at least one kinematic chain with gears. The kinematic chain may be chain open (with a fixed rotation joint) or closed chain (with at least two fixed joints). The kinematic chain with gears is attached to the kinematic chain with bars so that at least two gear wheels have centers in the bars of the bars and some wheels may be integral with the bars. In practice, some of these gears with gears and gears are known as planetary gears with cylindrical, conical or hipoidal gears.

The Effect of Selected Operational Factors on the Vibroactivity of Upper Gearbox Housings Made of Composite Materials

This paper presents the results of laboratory tests in which evaluation was performed regarding the effect of selected operating factors on the vibroactivity of upper gearbox housings made of three different fiber reinforced polymer composite materials with diverse layouts (cross and random) and types of reinforcing fibers: glass fiber and carbon fiber. The results of tests for composite housings were compared with those for a steel housing. The tests showed that composite housings had a weight lower by more than 60% compared to the steel housing. A multisensor measuring system consisting of vibration acceleration transducers, a directional microphone and a data acquisition card with software was used for the study. Tests of the vibroactivity of upper gear housings were carried out at different loads and rotational speeds of toothed gears. The study showed that composite housings are less sensitive to changes in the rotational speed that steel housings. The tests showed that at a higher rotational speed of the gear transmission, housings made of composite materials had a comparable or lower level of vibration. Tests and analyses of the vibroactivity of housings performed at different loads of the gear allow the conclusion that composite housings, despite a considerably lower weight than steel housings, are less sensitive to changes in the load of the gearing.

Backlash Identification in Two-Mass Systems by Delayed Relay Feedback

Backlash, also known as mechanical play, is a piecewise differentiable nonlinearity which exists in several actuated systems, comprising, e.g., rack-and-pinion drives, shaft couplings, toothed gears, and other machine elements. Generally, the backlash is nested between the moving parts of a complex dynamic system, which handicaps its proper detection and identification. A classical example is the two-mass system which can approximate numerous mechanisms connected by a shaft (or link) with relatively high stiffness and backlash in series. Information about the presence and extent of the backlash is seldom exactly known and is rather conditional upon factors such as wear, fatigue, and incipient failures in the components. This paper proposes a novel backlash identification method using one-side sensing of a two-mass system. The method is based on the delayed relay operator in feedback that allows stable and controllable limit cycles to be induced and operated within the (unknown) backlash gap. The system model, with structural transformations required for the one-side backlash measurements, is given, along with the analysis of the delayed relay in velocity feedback. Experimental evaluations are shown for a two-inertia motor bench that has coupling with backlash gap of about 1 deg.

Construction of Plastic Parts on CNC Engraving Machines and 3D Printers

This work presents some of researches performed by the authors on execution of plastic parts required for repair works specific to certain machines and plants. Authors focused especially on the repair and reconditioning of certain assemblies which include various machine parts: special spacers, machine-tools guides and toothed gears. Methods shown herein are very simple, accessible even to small workshop and they do not require special equipment, thereby involving minimal expenses. The use of simple programs allow fast and low-cost execution of parts with an accurately determined geometry.

Influence of the Mesh Geometry Evolution on Gearbox Dynamics during Its Maintenance

Toothed gears constitute the necessary elements of power transmission systems. They are applied as stationary devices in drive systems of road vehicles, ships and crafts as well as airplanes and helicopters. One of the problems related to the toothed gears usage is the determination of their technical state or its evolutions. Assuming that the gear slippage velocity is attributed to vibrations and noises generated by cooperating toothed wheels, the application of a simple cooperation model of rolled wheels of skew teeth is proposed for the analysis of the mesh evolution influence on the gear dynamics. In addition, an example of utilising an ordinary coherence function for investigating evolutionary mesh changes related to the effects impossible to be described by means of the simple kinematic model is presented.

Strategy of profile dividing gear grinding on Höfler grinding machines

The strategy of implementation of grinding operation of toothed gears with use of profile dividing method on Höfler grinding machines is presented. Results of this operation will depend on adopted strategy and machining conditions and the type of tool.

ANALYSIS OF CONTACT AND BENDING STRESSES IN GEARBOX SWITCHING UNDER LOAD

The work analyses contact stresses that occur within the active surface of toothed gears as well as bending stresses that take place at the tooth root. Contact stresses have been designated at the beginning of the singletooth engagement area within the pitch point and in the end of single-tooth engagement area. Designation of bending stresses at the tooth root has been made by applying the interteeth force to the external point of single-tooth engagement. The calculated numerical values of contact and bending stresses were compared to fatigue contact durability σH lim and fatigue bending strength σF lim that were obtained experimentally. Calculations of contact stresses and bending stresses were done with multi-criterion optimisation, which makes it possible to select such geometrical parameters of toothed gears that allow utilizing fatigue durability σH lim and σF lim in reference to a given material and technology of manufacturing toothed gears.