Search

Portable bandsaws are gaining in popularity for their use on remote jobsites to efficiently cut structural materials such as bar, pipe, and channel. Some of their increased popularity is due to the recent introduction of high watt-hour lithium ion batteries, which has further improved the portability of bandsaws by making them cordless. However, with cordless bandsaws, knowledge of cutting rates becomes more important as battery runtime limits productivity. Unlike industrial cutoff bandsaws that typically have feed rate control, the cutting rate of portable bandsaws is determined by operator applied pressure and gravity. While some research has highlighted the cutting mechanics of bandsaws and related wear processes, there is a lack of progress in the area of predicting cutoff time as a function of sawing parameters, such as applied thrust force, blade speed, workpiece material properties, and geometry of the cross section. Research was conducted to develop and experimentally verify a mechanistic model to predict cutting rates of various cross sectional geometries with a gravity fed portable bandsaw. The analytical model relies upon experimental determination of a cutting constant equation, which was developed for a low carbon steel workpiece cut with an 18 teeth per inch (TPI) blade. The model was employed to predict crosscutting times for steel rounds, squares, and tubes for several conditions of thrust force and blade speed. Model predictions of cutting time were in close agreement with experimental results. [ABSTRACT FROM AUTHOR]

Abstract: Dynamics of axially moving material continuum is investigated for over 60 years. Research interest in this subject is still high due to more and more new fields of application. Alongside traditional applications, such as band saws’ blades and axially moving paper webs, appeared as flat objects moving at high speeds in space. Recently many studies on the dynamics of axially moving beam-like and plate-like systems were published. Inclusion in analysis viscoelastic properties of broad moving continua is also the subject of research. The paper presents a review of research in this field with particular emphasis on the axially moving plate-like elastic and viscoelastic systems. Unlike the string-like and beam-like systems, such review on the plate-like systems has not been published yet. A brief overview of the most important studies on the dynamics of moving string-like and beam-like systems is presented as well. This paper also includes a comparative analysis of some results of studies published by the authors in the field of dynamics of axially moving viscoelastic systems. Some suggestions on the directions of further research in this field end the paper. [Copyright &y& Elsevier]

Mechanical systems including conveyor belts, band saw blades, and power transmission belts are influenced by the lateral motion of the moving structure. This phenomenon was studied in the literature both using the theory of the continuous linear and nonlinear systems and following the multibody technique. The subject is studied by using the finite element method (FEM) validated with reference to the analytical models described in the literature. The contributions of the Coriolis forces, the negative stiffness linked to the transport speed, and the bending stiffness due to the transverse moment of inertia are discussed. The dynamic behavior of a prototypical belt transmission layout with two fixed pulleys and an automatic tensioner is then analyzed. The results show the effect of the transport speed on the reduction of the flexural natural frequencies of the mode shapes strictly related to the lateral motion of the belt span and evidence the design strategy that needs to be followed for a correct operation of the whole system. [ABSTRACT FROM AUTHOR]

This study aims to estimate the age of segregation of young and mature wood of Luehea divaricata Mart., using the radial variation of specific gravity. To the development of this study were collected ten trees from two regions of the state of Rio Grande do Sul. Discs with thickness of 2cm at 0.1m of height from the base of the trunk were used. From each disk, with the aid of a band saw, a central ribbon 2.0cm wide, and oriented in the radial direction was taken, including the pith, then splitted into two samples "A" and "B". The specific gravity was calculated as ratio between dry weight and wet volume. The wet volume was determined according to ASTM D 2395 - 93, 1997. The age of segregation was found by simple linear regression of the data of variation of specific gravity from pith to bark. The intersection of extrapolated lines was adopted as the age of segregation. The results showed that the wood segregates in 26 year for the region of Central Depression and in 23 years for the Northeast Upper Hillside. Was made a multifactorial analysis of variance in the specific gravity data, showing that there are statistical difference between regions and woods. However, there are no statistical difference between samples. [ABSTRACT FROM AUTHOR]

Cutting tool industries face an enormous challenge in finding the conditions that result in economically viable machining of titanium alloys such as Ti-17. The generation of high thermal and mechanical stresses in cutting tools during machining of titanium alloys accelerates tool wear and this significantly affects tool life, productivity and product quality. The application of advanced coatings on cutting tools has become an important way to improve the tool performance when machining titanium alloys. Recently, nano-structured TiAlSiN coatings have attracted increasing attention as an alternative to traditional TiN coatings, mainly due to its superior oxidation resistance at elevated temperatures and improved mechanical properties, which are ideal for machining titanium alloys. Very little attention has been given to the investigation of primary machining operations such as bandsawing. In this investigation, tungsten carbide-tipped bandsaw teeth were coated with TiAlSiN coating. The coating was characterized for structural, chemical and mechanical properties. Machining tests were carried out on Ti-17 alloy in a modified lathe using uncoated and TiAlSiN-coated bandsaw teeth. Forces were measured during the cutting tests and the specific cutting energy was calculated using the obtained force and material removal rate data. Wear modes and mechanisms in the bandsaw teeth were investigated using a scanning electron microscope and energy dispersive X-ray analysis. The results show that a TiAlSiN-coated bandsaw tooth performed better than an uncoated bandsaw tooth in terms of wear and specific cutting energy. [ABSTRACT FROM AUTHOR]

The bandsawing as a multi-point cutting operation is the preferred method for cutting off raw materials in industry. Although cutting off with bandsaw is very old process, research efforts are very limited compared to the other cutting process. Appropriate online tool condition monitoring system is essential for sophisticated and automated machine tools to achieve better tool management. Tool wear monitoring models using artificial neural network are developed to predict the tool wear during cutting off the raw materials (American Iron and Steel Institute 1020, 1040 and 4140) by bandsaw. Based on a continuous data acquisition of cutting force signals, it is possible to estimate or to classify certain wear parameters by means of neural networks thanks to reasonably quick data-processing capability. The multi-layered feed forward artificial neural network (ANN) system of a 6 × 9 × 1 structure based on cutting forces was trained using error back-propagation training algorithm to estimate tool wear in bandsawing. The data used for the training and checking of the network were derived from the experiments according to the principles of Taguchi design of experiments planned as L. The factors considered as input in the experiment were the feed rate, the cutting speed, the engagement length and material hardness. 3D surface plots are generated using ANN model to study the interaction effects of cutting conditions on sawblade. The analysis shows that cutting length, hardness and cutting speed have significant effect on tooth wear, respectively, while feed rate has less effect. In this study, the details of experimentation and ANN application to predict tooth wear have been presented. The system shows that there is close match between the flank wear estimated and measured directly. [ABSTRACT FROM AUTHOR]

The article presents a free vibration analysis of a moving Bernoulli-Euler beam through the use of the differential transform method (DTM). In the study, the differential equation of a moving Bernoulli-Euler beam with axial force effect, as well as its free flexural vibration properties are determined. The results of the study were compared with that of the analytical method. Several examples of axially moving beams are cited, including power transmission belt and chain drives, band saws and aerial cable tramways.

Sawmilling can add value to wood produced in small rural properties. The aim of this paper was to evaluate the quality of Pinus elliottii lumber saw-milled using the first prototype of portable sawmill made by the partnership among a research institution and industrial corporation. During saw-milling there were evaluated the volume yield, maximum productivity, cutting deviation, and feed speed of the prototype. The tests performed revealed that the prototype needs some mechanical modifications in order to decrease cutting deviation of the last saw-milled boards from the log. However, the volume yield was greater than 71%, the feed speed of the prototype were between 0.94 and 1.82 m/s, and the maximum productivity was 2.17 m³/h, these values are equal or better than those reached by similar imported equipments. The maximum cutting deviation was below the level allowed by the Brazilian standard NBR PB 1560. [ABSTRACT FROM AUTHOR]

Abstract: In cutting operations by multipoint cutting tools such as bandsawing, the layer of material removed per tooth (5–30μm) is usually less than or equal to the cutting edge radius (5–15μm). Furthermore, the bandsaw tooth is also restricted since it has to accommodate the chip in a gullet of limited size. This situation can lead to inefficient metal removal by a combination of piling up, discontinuous chip formation and ploughing action in contrast to the cutting operations by most of the single point cutting tools (e.g., turning). Specific Cutting Energy (ESP ) is a better way of measuring the efficiency of the metal cutting process compared to the other processes such as determining tool wear, cutting forces, chip ratio, etc. This paper reports on the full bandsawing tests of three different workpiece materials (Ball bearing steel, Stainless steel and Ni–Cr–Mo steel). The increase of ESP throughout the life of the bandsaw reflected the degradation of the cutting performance due to the wear of the cutting edge geometry for Ball bearing and Stainless steels. However, there was no increase in ESP when cutting Ni–Cr–Mo steel, which could be explained by the existence of a large protective built-up edge and/or minimal blade wear. The variation of the ESP in different workpiece materials will also provide valuable information for bandsaw manufacturers and end users to estimate machinability characteristics for selected workpieces. [Copyright &y& Elsevier]

Abstract: In bandsaw machines, it is desired to feed the bandsaw blade into the workpiece with an appropriate feeding force in order to perform an efficient cutting operation. This can be accomplished by controlling the feed rate and thrust force by accurately detecting the cutting resistance against the bandsaw blade during cutting operation. In this study, a neural-fuzzy-based force model for controlling band sawing process was established. Cutting parameters were continuously updated by a secondary neural network, to compensate the effect of environmental disturbances. Required feed rate and cutting speed were adjusted by developed fuzzy logic controller. Results of cutting experiments using several steel specimens show that the developed neural-fuzzy system performs well in real time in controlling cutting speed and feed rate during band sawing. A material identification system was developed by using the measured cutting forces. Materials were identified at the beginning of the cutting operation and cutting force model was updated by using the detected material type. Consequently, cutting speed and feed rate were adjusted by using the updated model. The new methodology is found to be easily integrable to existing production systems. [Copyright &y& Elsevier]

Electronic Speckle Pattern lnterferometry (ESPI) is used to measure the vibration mode shapes of circular and bandsaws. A video camera views a vibrating sawblade that is illuminated by a laser light. The image within the camera is mixed with a reference light to create an interference pattern. The reference phase is stepped by 180 degrees using a piezoelectric actuator before measuring each successive image. Subtraction of the successive images gives a contour view of the vibration mode of the sawblade. The technique is noncontacting and displays vibration mode shapes in real-time. It has the advantage over the classical Chladni method because it avoids the need to spread a powder over the sawblade surface and because it can also identify low-frequency vibrations. [ABSTRACT FROM AUTHOR]

This paper examines the feasibility and application of an active control strategy to reduce the transverse and torsional vibrations of a moving wood saw band.A nonlinear control strategy and an adaptive signal processing technique are applied to an experimental test stand of a moving band with adjustable tension. The nonlinear control allows the control system to quickly adapt to changes in vibration magnitude and provides an effective means for suppressing vibrations caused by external excitations and internal resonance. The on-line control is performed through a DSP (digital signal processing) board and control actuation is provided by non-contact electromagnetic forces. Experimental results show that the applied actuation suppressed both the transverse and torsional vibrations of the moving band, significantly reducing the vibration amplitude. The robustness of the active control is also investigated as a function of the input location of the control force. [ABSTRACT FROM AUTHOR]

The use of easily adjusted equipment — a combination rolling-mill and drawbench, modernized drum-type drawbenches, and modern band saws — to obtain light sections has made the production process much more flexible and efficient, improved product accuracy, and realized a substantial savings in expensive nonferrous metals and alloys. Customers’ strict requirements on the condition of the product surface are now being met as a result of improvements to the light annealing administered to the semifinished products, use of the latest lubricant-coolants for drawing, the introduction of new equipment to transport bundles of long semifinished products between operations, and the implementation of several other measures. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents an application of the rigid finite element method to modelling of the arm of a band saw. The equations of motion are derived using the Lagrange equations and methods used in analysis of multi-body systems. The method presented enables interactions between the base and the frame to be taken into account. The influence of flexibility of some elements of the band saw on natural frequencies is shown. [Copyright &y& Elsevier]

The development of band saws for the cutting of aluminium plates has been growing up during the last 15 years. This technology faces several difficulties regarding blade vibrations and blade lifetime. Concerning the band sawing process, all the research works published up to now are dealing with wood-cutting. In this paper, a review of the most important literature published on the subjects of band saw vibrations and stresses into blades is presented with a special attention to the latest research developments. The application of this state-of-the-art to the case of aluminium-cutting using modern high-speed band saws is discussed and interesting research directions are highlighted. [Copyright &y& Elsevier]