Utjecaj promjenjivog koraka zubi kružnih pila na snagu za poprečno rezanje drva

The article deals with the influence of irregular tooth pitch on energy consumption of cross-cutting wood. In this article, the effect was assessed of feeding velocity and parameters of saw blade on the cutting power Pc of spruce (Picea Abies), pine (Pinus Sylvestris) and beech (Fagus Silvatica) wood during sawing with a guided circular saw. For the research, two types of circular saw blades were used, one of them having irregular tooth pitch. The circular saw blades had sintered carbide inserts with a diameter of D = 350 mm and the same number of teeth. The feed velocities were vf = 4, 8,12 m∙min-1 and revolutions n = 3000 min-1. The results showed that the circular saw blades with irregular tooth pitch have higher energy consumption than the circular saw blades with regular tooth pitch. The highest cutting power Pc was shown in the case of beech. It was also shown that energy consumption is increasing linearly with increasing feed velocity.U radu se prikazuje istraživanje utjecaja promjenjivog koraka zubi kružnih pila na potrošnju energije pri poprečnom rezanju drva. Analiziran je utjecaj posmične brzine, parametara lista pile i vrste drva na snagu rezanja (Pc). Eksperiment je proveden piljenjem drva smreke (Picea abies), bora (Pinus sylvestris) i bukve (Fagus silvatica) vođenom kružnom pilom. Za istraživanje su rabljena dva lista kružnih pila, od kojih je jedan imao promjenjivi korak zubi. Oba su lista kružnih pila imala oštrice od sinteriranih karbidnih umetaka, promjer lista D = 350 mm i jednak broj zubi. Primijenjene su tri posmične brzine: 4, 8 i 12 m∙min-1, a broj okretaja radnog vratila iznosio je n = 3000 min-1. Rezultati su pokazali da je potrošnja energije kružnih pila s promjenjivim korakom zubi veća od potrošnje energije kružnih pila s jednakim korakom zubi. Najveća snaga rezanja Pc zabilježena je pri piljenju bukve. Uočeno je da se potrošnja energije linearno povećava s povećanjem posmične brzine

Utjecaj projektnih parametara uređaja za horizontalno cijepanje drva na silu cijepanja

The article deals with the influence of the shape of the splitting wedge on the size and course of splitting force. Today maximum effort is made to search for and use of energy saving solutions in every industry. Such solutions can include a change of the form of the longitudinal splitting wedge for splitting logs. The core of this problem is the experimental detection of powers, followed by analising the individual effects. For this purpose, an experimental device was designed. The base of equipment consists of a mobile horizontal splitter, which is well adapted to capture the process of splitting force in splitting logs. According to the results, the type of wood was the most influencal factor, followed by wood diameter and splitting wedge. When comparing the average values that were generated from repeated measurements, it is possible to follow the reduction of splitting force. The results showed that the splitting force was reduced by approximately 13 % when comparing splitting wedge No. 1 (simple) and No. 2 (refracted). When comparing splitting wedges No. 1 (simple) and No. 3 (concave), it can be observed that the splitting force was reduced by more than 50 %. The experiment also confirmed the effect of different anatomical structures of different species of wood on various physical and mechanical properties of such wood and hence also on the splitting force in splitting wood.U članku se govori o utjecaju oblika klina za cijepanje drva na veličinu i smjer sile cijepanja. U današnje vrijeme ulažu se veliki napori u pronalaženje i primjenu novih riješenja za uštedu energije u svim industrijama. Jedno od takvih rješenja može predviđati i promjenu oblika klina za uzdužno cijepanje trupaca. Za taj problem važno je eksperimentalno odrediti snagu te analizirati pojedinačne utjecajne parametre. Za tu svrhu izrađen je eksperimentalni uređaj za cijepanje drva. Baza opreme sastoji se od mobilnoga horizontalnog razdjelnika, koji je dobro prilagođen praćenju procesa cijepanja i sile za cijepanje trupaca. Rezultati su pokazali da najveći utjecaj na silu cijepanja ima vrsta drva, zatim promjer drva i, na kraju, oblik klina za cijepanje. Usporedbom prosječnih vrijednosti dobivenih ponovljenim mjerenjima može se pratiti smanjenje sile cijepanja. Rezultati su pokazali smanjenje sile cijepanja za oko 13 % ako usporedimo cijepanje uz pomoć klina 1 (jednostavni) i klina 2 (slomljeni). Usporedimo li klinove za cijepanje broj 1 (jednostavni) i broj 3 (konkavni), može se uočiti smanjenje sile cijepanja za više od 50 %. Eksperiment je također potvrdio utjecaj anatomske građe različitih vrsta drva na fizikalna i mehanička svojstva drva, a time i na silu cijepanja pri obradi drva cijepanjem

The possibilities for measurement of saw blades wearing

Some effects come into the practice because of decreasing quality of a cutting knife. These effects then influence the whole cutting process. The paper deals with analysis of methods for evaluation of a chain saw wearing. It is necessary to know the methods for measurement of a chain saw wearing because the tool wearing has significant influence on the whole system acting i.e. machine-tool-work piece. The measurement of wearing rate was realized to obtain knowledge about the wearing rate of cutting knives on chain saws. The goal of measurement was to design suitable methods for evaluation of wearing and definition of exactness for used methods. The exactness of used methods is evaluated according to the range of variance. The cutting knife wearing was analyzed by two methods; the results of both methods were compared. In the future it would be very effective to generalize mentioned methodology for measurement of a cutting knife wearing

Wood Crosscutting Process Analysis for Circular Saws

This article deals with the influence of some cutting parameters (geometry of cutting edge, wood species, and circular saw type) and cutting conditions on the wood crosscutting process carried out with circular saws. The establishment of torque values and feeding power for the crosswise wood cutting process has significant implications for designers of crosscutting lines. The conditions of the experiments are similar to the working conditions of real machines, and the results of individual experiments can be compared with the results obtained via similar experimental workstations. Knowledge of the wood crosscutting process, as well as the choice of suitable cutting conditions and tools could decrease wood production costs and save energy. Changing circular saw type was found to have the biggest influence on cutting power of all factors tested

The Impact of Design Parameters of a Horizontal Wood Splitter on Splitting Force

The article deals with the influence of the shape of the splitting wedge on the size and course of splitting force. Today maximum effort is made to search for and use of energy saving solutions in every industry. Such solutions can include a change of the form of the longitudinal splitting wedge for splitting logs. The core of this problem is the experimental detection of powers, followed by analising the individual effects. For this purpose, an experimental device was designed. The base of equipment consists of a mobile horizontal splitter, which is well adapted to capture the process of splitting force in splitting logs. According to the results, the type of wood was the most influencal factor, followed by wood diameter and splitting wedge. When comparing the average values that were generated from repeated measurements, it is possible to follow the reduction of splitting force. The results showed that the splitting force was reduced by approximately 13 % when comparing splitting wedge No. 1 (simple) and No. 2 (refracted). When comparing splitting wedges No. 1 (simple) and No. 3 (concave), it can be observed that the splitting force was reduced by more than 50 %. The experiment also confirmed the effect of different anatomical structures of different species of wood on various physical and mechanical properties of such wood and hence also on the splitting force in splitting wood.U članku se govori o utjecaju oblika klina za cijepanje drva na veličinu i smjer sile cijepanja. U današnje vrijeme ulažu se veliki napori u pronalaženje i primjenu novih riješenja za uštedu energije u svim industrijama. Jedno od takvih rješenja može predviđati i promjenu oblika klina za uzdužno cijepanje trupaca. Za taj problem važno je eksperimentalno odrediti snagu te analizirati pojedinačne utjecajne parametre. Za tu svrhu izrađen je eksperimentalni uređaj za cijepanje drva. Baza opreme sastoji se od mobilnoga horizontalnog razdjelnika, koji je dobro prilagođen praćenju procesa cijepanja i sile za cijepanje trupaca. Rezultati su pokazali da najveći utjecaj na silu cijepanja ima vrsta drva, zatim promjer drva i, na kraju, oblik klina za cijepanje. Usporedbom prosječnih vrijednosti dobivenih ponovljenim mjerenjima može se pratiti smanjenje sile cijepanja. Rezultati su pokazali smanjenje sile cijepanja za oko 13 % ako usporedimo cijepanje uz pomoć klina 1 (jednostavni) i klina 2 (slomljeni). Usporedimo li klinove za cijepanje broj 1 (jednostavni) i broj 3 (konkavni), može se uočiti smanjenje sile cijepanja za više od 50 %. Eksperiment je također potvrdio utjecaj anatomske građe različitih vrsta drva na fizikalna i mehanička svojstva drva, a time i na silu cijepanja pri obradi drva cijepanjem

Design Solution for a Device to Determine the Energy Consumption of Sawing Wood with Chain Saws

Cutting wood chips is one of the common work procedures in the course of processing wood with a saw chain. This paper presents the conceptual design of the device and the design of the device for determining the energy demand of such a process. The preparation is designed with the given parameters to achieve the most realistic conditions for sawing wood. It must contain the original cutting device from the STIHL MS 261 chainsaw. It consists of several calculations to determine the cutting moment and the loaded points of the preparation, which define the possible place of damage. In the conceptual design, calculations for cutting force Fr = 924 N and tensile force Fn = 290 N are processed in the work. From the calculated forces, it is possible to determine the resulting stress at the attachment or critical points. For comparison, a finite element method analysis was created in Creo Parametric. The results of the analysis confirm the appropriate selection of material and parameters for the application of the preparation to the test device. The resulting voltages, corresponding to a maximum value of 132 MPa, are negligible for this type of preparation in terms of safety and durability

Research on the side deflection of the saw band of a joinery band saw influenced by the selected technical and technological factors

The paper focuses on measuring and evaluating the impact of selected technical and technological factors - the height of adjustable guides and stretching force - on the side deflection of the saw band of a joinery band saw. There is a detailed description of the ways the side deflection can be measured. In order to find out the intensity of the stretching force was used portable tension meter SANDVIK 5000, enabling to check the tensile stress in the saw blades of a gang saw or in the saw bands of a band saw. The actual experiment was conducted on a joinery band saw, at the cutting rate vc = 15 m·s-1. The results of the measurements confirmed the theoretical assumption of the impact of the selected technical and technological factors on the stability of the saw band, where the side deflection decreases with increasing stretching force and increases with increasing height of the guides. The stability of the saw band affects the quality of the surface to be treated, thus saving the cost of machining the workpiece and making work productivity more efficient

The Impact of Weather-Forecast-Based Regulation on Energy Savings for Heating in Multi-Family Buildings

In this study, based on 19 years of research, an analysis of thermal energy consumption for heating was carried out on a group of 22 residential multi-family buildings located in a temperate continental climate. The buildings were constructed with two different technologies based on prefabricated elements, and most of them were equipped with central heating cost allocators. A predictive control system for the central heating system was installed in the analyzed buildings, followed by a deep thermo-modernization. An evaluation was made regarding whether the use of a change in the method of central heating control, from the traditional one, which takes into account only the variable external temperature, to weather control, increases the energy efficiency of the thermo-modernized buildings. In addition, the cost-effectiveness of the modernization measures was analyzed by determining economic efficiency indicators; therefore, it was possible to identify the modernization variant that, with limited investment costs, could achieve the best energy efficiency resulting from the European energy policy

Testing of Cutting Tools on a Pneumatic Experimental Device and Evaluation of Cutting Edge Wear Using a Non-Contact 3D Method

This research is focused on the evaluation of cutting edge wear of the delimbing knife by contactless methods. Delimbing knives were tested in an experimental device constructed in our laboratory, which operates on the principle of a forest harvester head. The greatest wear of the cutting edge was manifested in knife no. 1 with a blade angle of ∢ 7°. The research was focused on the wear of delimbing knives made of DIN 58SiCr8/WNr material when changing the angular geometry of the tool and using a constant delimbing speed of 2.0 m.s−1 while delimbing spruce wood of various wood diameters. The Alicona Infinite Focus device, which functions as a non-contact 3D optical device, was used to determine the amount of wear on the cutting edge of the knife. The size of cutting edge wear significantly affects chipless cutting wood, which can be observed in an increase in the cutting force during the delimbing process. The use of harvester technology in forestry is a highly topical issue today. From this point of view, it is necessary to focus on increasing the efficiency and reducing the energy consumption of the machine, which economically benefits its delimbing operation

Innovative Solutions for Increasing the Service Life of Cutting Head Components Using Finite Element Method Analysis

Chipless tree cutting is increasingly becoming more popular because of its low weight and greater throughput due to the small dimensions of the entire cutting head. This paper is focused on the design of the crank plate of the cutting mechanism of a chipless cutting head. It was necessary to calculate the magnitude of the force required to cut the tree in the direction perpendicular to the growth of the tree fibers. In addition, the tree and cutting mechanism parameters were specified. Due to the size of the cutting force, it was possible to further deduce the amount of the discharge force from the linear motor that directly acts on the opening of the crank plate. After finite element method analysis, it was found that the crank plate was undersized and it was necessary to increase its thickness from 15 mm to 30 mm, which eliminated the problem of plastic deformation