OVERVIEW OF MODERN WOODEN HOUSING CONSTRUCTION IN RUSSIA

Wooden house building has centuries-old traditions, to which Russia has made a significant contribution. Historically, our country is rich in forests, hence the quite natural choice of wood as the main material for housing construction. Everyone knows the methods of building wooden houses by Russian architects of the early Middle Ages “with one ax and without a single nail.” Well, of course, we must understand here that there was more than one ax, there were auxiliary manual wood-cutting tools. Well, without nails – it does not mean at all that the connecting elements were not used, they just were also wooden. Some of these monuments of wooden architecture have survived to this day and we can observe them, for example, in Kizhi, Vologda, Arkhangelsk and many other cities.

Device for Wood-Cutting Tool Hardening

Choosing effective methods and devices for surface hardening of wood-cutting tools is problematic due to the variety of their designs and operating conditions. In this regard, the development of such devices becomes an urgent task. According to the literature, one of the effective methods for increasing the service life of machine parts and tools is electrospark hardening or electrospark alloying. Industrial electrospark installations such as “EFI” (electrophysical measurements) and “Elitron” with manual vibrators are used for electrospark hardening. However, using manual vibrators significantly increases the labour intensity and hardening time. Moreover, the surface quality after hardening with manual vibrators is often unsatisfactory. Various mechanized installations have been developed in order to reduce the labour intensity of electrospark hardening. Nevertheless, these installations are designed to harden specific parts and do not allow hardening tools of various designs, including woodcutting tools. The surface quality after hardening in mechanized installations does not always satisfy the customer. Further surface plastic deformation treatments, such as rolling and unrolling with rollers and balls, as well as diamond burnishing, are often used to improve the surface quality after electrospark hardening. The surface quality after additional processing by these methods boosts, although the labour intensity and cost of the hardening process increase. To increase the wear resistance of machine parts and tools, it is reasonable to reduce the height parameters of roughness, increase microhardness, and form the residual compressive stresses, which is ensured by the methods of surface plastic deformation. In this regard, it becomes necessary to use electrospark hardening simultaneously with surface plastic deformation. The work presents the design and features of using the device for hardening. The device was used to strengthen the thicknesser machine knives, which made it possible to almost double their durability. Applying this device, in comparison with using the electrospark hardening with a manual vibrator, reduces the roughness of the hardened surface and improves the surface quality of the processed workpieces. The modes of hardening have been installed, making it possible to effectively harden wood-cutting tools. For citation: Buglaev A.M. Device for Wood-Cutting Tool Hardening. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 134–141. DOI: 10.37482/0536-1036-2021-5-134-141

Modeling of Discrete Contacts for the Thermodynamic Element System of a Modular Wood-Milling Cutter

Operational capability of a modular wood-cutting tool depends, besides many factors, on the design features of cutting element fastening unit. There are no clear and precise methods that explain major factors influencing tool durability for selecting the design of the modular wood-cutting tool, which would meet production requirements. Thermodynamics modeling under contact interaction of elements enables to choose a design for effective application and increases the tool efficient life. The research purpose is modeling of thermodynamic processes in the cutter element fastening unit in the wood-cutting tool body in order to optimize the design, technological parameters and operating modes of the tool. The research subject is the contact interaction conditions and heat transfer processes between the device elements. The cutting element fastening unit is designed and the model of interaction between the parts of the mechanism of the modular wood-milling tool is developed. Further tasks, namely, development of a model of thermodynamic processes in the cutting element fastening unit, discussion of the results and identifying the recommendations for choosing the design of the modular wood-cutting tool at the design stage were realized in a work that continues the ongoing research. The finite-element model of rough wavy surfaces contact interaction of design elements was developed on the basis of standard design of a shell-type plain woodmilling cutter. The analysis concluded that further analytical modeling of contact conditions with existing parameters is possible. The contacting surfaces approach and the radii of single contact areas were determined taking into account the data of design and calculation of wood cutting forces. These results will be used next in modeling of thermodynamic processes. Methodology and research methods comprise theoretical study and mathematical modeling, including finite-element analysis. The models developed are possible to be used in the creation of a complex durability model of the wood-cutting tool with regard to other factors. The main result of this research stage is obtaining the model of contact conditions and initial data for further modeling of thermodynamic processes in the knife fastening unit in the milling body to predict its thermal condition.

The Effect Of Noise On The Level of Concentration In Wood Cutting Workers In Arjasa District, Jember District

Disorders of concentration in workers can cause workplace accidents due to decreased ability to focus attention when working. The annual work accident rate is estimated at 250 million with 1.2 million people dead. One of the causes of disturbances in worker concentration is the physical factor in the form of noise. One of the high intensity noise is found in the wood cutting industry in Arjasa District, Jember. The aim of this study is to analyze the effect of noise on the concentration level in wood cutting workers in Arjasa District, Jember. This is an analytic observational research with cross sectional study. The respondents amounted to 32 people taken with purposive sampling. The measurement of noise was using a sound level meter. The measurement of concentration level using Trail Making Test (TMT) A and B. Concentration level measurement is done when the respondent has worked for 30 minute. The results of the study showed that the majority of respondents were aged between 25-28 years (28.1%) and had worked less than the same as 2 years (53.1%). The average noise intensity of the wood cutting area was 97.5 dB (A) and the loading and unloading area was 76.2 dB (A). Average noise intensity of the wood cutting area exceeds the noise threshold value. The level of concentration of workers in the wood cutting area is lower than the loading and unloading area workers. The results of data analysis using the independent t test indicate that there are differences in the mean TMT B score: TMT A between respondents who work in noisy and non-noisy environments (p=0,004). There was a noise effect on the concentration level in wood cutting workers in Arjasa District, Jember Regency. Keywords: Noise, concentration, wood cutting workers

The impact of wood cutting and of bush fires on the dynamics of the herbal strata of Sudano-Guinean Savanna

Few studies were carried out on the impact of wood cutting and bush fires on the dynamics of the herbal strata in savannahs of Adamawa, Cameroon. This study has as objectives to evaluate: 1. the recovery of the vegetation of shrub and grass savanna, 2. the evolution of the number of herbs with regards to time, 3. the floristic and specific contribution of the herbal specie. The inventories of herbaceous plants were carried out through quadra method in 9 sub-plots of 10 m × 10 m for each vegetal formation. The experimental design was split-plot with two (02) factors (savanna trees and shrubs), three (3) treatments (felling without fire, with fire and witness) and three (3) rehearsals/repetitions (portions). The analysis of variance (ANOVA) was used to compare means between treatments by using STATGRAPHIC XVII, and XLSAT to obtain result shown that 103 herbaceous plants divided in 73 genres and 23 families. The rate of recovery of savanna vegetation the herbs are more numerous 60% in the CSF, 50% in the CAF and 45% in witness site (wood savanna), Adversely, 30% in a witness site, 40% in the CSF and 50% in the CAF (shrub savanna). The number the species have grown from 3 to 45 in the tree’s savanna and 2 to 34 for the shrub savanna. The specific contribution of herbaceous varies according to the sites and the species.

Selection of interlocking side mills based on modeling thermodynamic processes during cutting. Part 1. Modeling the conditions of contact interaction

The results of research on improving the design of wood-cutting mills are presented. A model of interaction of elements of an assembled cutting tool has been developed to select its structure at the design stage. Initial data and conditions of contact interaction are obtained for modeling thermodynamic processes in the knife attachment unit. Keywords: easy-to-work material, wood-cutting interlocking side mill, attachment point, cutting element, conditions of contact interaction. [email protected]

Effect of N95 Masks on Furniture-cutting Workers with Respiratory Symptoms

In a preliminary survey of furniture workers in 2017, 8 out of 15 workers reported that the wood-cutting process always led to tightness in their chest and made them cough. This is because the wood-cutting process produces dust and the workers do not use any personal protective equipment such as mask at work. Therefore, the aim of this study was to find the effect of wearing masks on the respiratory symptoms of woodcutters in Sentra Mebel Kemirahan, Malang. The researchers distributed N95 masks to all the workers. The research used a pre-experimental with one group pre- and post-test design. The study included a total of 21 people, selected through purposive sampling. Data were analysed using the Wilcoxon test. The result of pre–post-tests in every variable were: (i) P-value 0.000 for chest tightness; (ii) P-value 0.001 for cough; (iii) P-value 0.000 for chest pain, which is P ≤ 0.005, meaning significant. Therefore, we conclude that there was a difference between before and after using N95 mask against the respiratory symptoms in the wood-cutting workers in Sentra Mebel Kemirahan Malang. Keywords: subjective respiratory symptom, chest tightness, cough, chest pain, N95 mask