Лесотехнически Университет

Summary

The methodology for calculation of the shafts and the axles subjected to deformation taking into account the radial clearance in the bearings is presented in the paper.

Deflection of the shafts and axles is determined for two cases: the first one is when the antifriction bearings are assumed to be perfectly solid supports and the second one is when the above-mentioned are assumed to be elastic.

The deflection of the antifriction bearings is a sum of the initial clearance and the elastic deformations of the antifriction bodies and their rings.

The aim of the present work is to determine the elastic deformations of the antifriction bodies and the rings of the bearings.

Summary

A mathematical model of the specific heat energy, which is needed for defrosting of wood materials in the hygroscopic range, qbfr, has been suggested. The specific heat energy qdfr consist of two parts: the energy needed for heating of the frozen wood until melting of the ice in it, qwfr, and the energy needed for the melting of the ice formed from the bound water in the wood, qbw. Using the suggested model computations have been carried out for the determination of qwfr, qbw and qdfr = qwfr + qbw during defrosting of oak, pine, beech, and poplar frozen wood with moisture content from 0.2 kg·kg-1 up to the border of the hygroscopic diapason and with initial temperature in the range from −20 oC to −2 oC, at which the thawing of the ice formed from the bounded water is completed.

Summary

By the first co-author earlier a 3-dimensional mathematical model has been created, solved, and verified for the transient non-linear heat conduction in frozen prismatic wood materials during their heating. Now in the model the dependence of the fiber saturation point of the separate wood species from the temperature has been incorporated.

The paper presents graphically solutions of the updated model of the obtained calculated results about the temperature distribution in the volume of beech frozen materials with prismatic shape with thickness 0,4 m, width 0,4 m, length 0,8 m, initial temperature -40 оC, and moisture content 0,3 kg.kg-1 and 0,6 kg.kg-1 during their defrosting at temperature of the processing medium of 80 оC.

Summary

The paper presents a new approach for the 3D colour visualization of the obtained with the help of own mathematical model calculated results about the non-stationary temperature distribution in the volume of frozen wood materials with prismatic shape during their defrosting. An example for the application of the approach for visualization of the temperature distribution in frozen beech prisms with thickness 0,4 m, width 0,4 m, length 0,8 m, initial temperature -40 оC, and moisture content 0,3 kg.kg-1 (wood with ice from the bounded water in it) and 0,6 kg.kg-1 (wood with ice from both the bounded and the free water in it) during their defrosting at temperature of the processing medium 80 оC has been given. The results from the studies can be used for the creation of an optimal energy saved thermal treatment of prismatic wood materials during their defrosting with an aim of following plasticizing in the veneer production.

Summary

Analysis of the load on the main drive shaft of band saw is provided in three cases:

Bending couples resulting from the strain forces of the saw band and the belt transmission are absorbed by the shaft.

The bending couple resulting from the force of strain of the saw bend is absorbed by the shell of the bearing unit and the bending couple caused by the strain force of the belt transmission is received by the shaft.

Bending couples from the strain forces of the saw band and the belt transmission are received by the shell of the bearing unit.

Strain forces of the saw band and the belt transmission loading the main drive shaft are determined. Validating test strength calculations of the main band saw shaft are made.

Constructive solutions to reduce the bending in the console parts of the main drive shaft which will improve the work of the saw band and the V-belt transmission are proposed.

Summary

This paper presents the structure and functions of system for automatic control of the rotation frequency of an alternating current powerful electromotor of the cutting mechanism of machine for slice veneer production. In the system a microprocessor programmable frequency regulator for the supplying of the controlled electromotor have been inbuilt.

There is already the automated system integrated, as a result of which the productivity of the veneer slice machine has improved significantly, the specific energy consumption has reduced and the intellectual pressure of the operator has decreased.

Summary

By the first co-author earlier a two-dimensional mathematical model has been created, solved, and verified for the transient non-linear heat conduction in frozen logs during their heating. Now in the model the dependence of the fibre saturation point of the separate wood species from the temperature has been incorporated.

The paper presents graphically solutions of the updated model and the 3D and 2D visualization of the obtained calculated results about the temperature distribution in the longitudinal section of beech frozen logs with diameter 0,4 m, length 0,8 m, initial temperature -40 oC and moisture content 0,3 kg.kg-1 and 0,6 kg.kg-1 during their defrosting at temperature of the processing medium 80 oC.

Summary

Analysis of the driving of the cutting mechanism for band saw is provided. The forces exercising an effort on the main band saw shaft resulting from the cutting of the band saw and the V-belt gear are determined. Validating calculations on static strength and fatigue of the main drive belt of the band saw are made.

Summary

A methodology for the creation of colourful 2D diagrams using MS Excel 2010, illustrating the temperature distributions in the longitudinal sections of frozen logs during different moments of their defrosting, has been suggested in this paper. For the creation of the diagrams numerical results have been used, which represent the solutions to a non-linear mathematical model of the logs’ defrosting process. These numerical results are presented in files in the .txt format before their processing with the software of MS Excel 2010 aiming at the creation of the 2D colourful diagrams.

Summary

In the first and at the beginning of the second part of this work the methodology for creation of 2D colourful diagrams has been described as thematically-oriented sequence of the used procedures of MS Excel 2010. In this part of the work the methodology has been applied for the preparation of 2D colourful diagrams of temperature distribution in the longitudinal sections of a frozen oak log during its defrosting. The methodology can be used for the preparation of various 2D diagrams for the change of temperature, moisture, and other fields in the volume of different materials in the cases when the diagrams are created using extensive numerical results from models, adequately describing the studied processes.