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1.
Summary Three new approaches to kerfless wood cutting are evaluated: (1) vibrating cutters; (2) high-velocity liquid jet; and (3) laser beam. Their origin and recent developments are discussed in detail, based on the current research findings. Particular emphasis is placed on the possibilities for industrial application of these techniques.From this evaluation it is apparent that the high-velocity liquid jet and laser beam offer great potential in secondary manufacture, in particular for cutting of intricate contours and complex computer-controlled operations. Kerfless cutting with vibrating cutters cannot be objectively evaluated at present because of lack of sufficient theoretical and experimental work. 相似文献
2.
Dr. B. E. Klamecki 《Wood Science and Technology》1976,10(3):209-214
The variation of the coefficient of friction with normal load and tool surface finish in slow speed orthogonal cutting of white fir was investigated to determine the relative importance of different sources of friction. Cutting forces were measured as a function of tool-chip contact length and tool surface roughness. The coefficient of friction was independent of tool roughness for roughness in the range of typically well-finished cutting tools but did become a factor for large values of tool surface roughness. The data indicate that for well-finished cutting tools the primary friction mechanism is adhesion between the tool and work and that for rough tool surfaces the effect of tool surface asperities (unevennesses) as they advance through the chip becomes an important source of friction. 相似文献
3.
Jin Weizhu Kong Degang Northeast Forestry University 《林业研究》1991,2(1):108-112
Oblique cutting of wood is an important form of cutting wood.With the developingof woodworking industry,it is widely used in wood machinary processing such as planing,milling,sawing,drilling and so on.This paper takes oblique planing and helix milling of wood as examples.The influences of bevel angle and other factors on the cutting force have been shown.The changingrules of cutting forces have been summarized.On the basis of it,we especially carried out theoreticalanalysis on the changing rules of cutting forces and discussed the influence of the changing rules onpractice. 相似文献
4.
Summary Slow speed wood cutting tests were carried out in which cutting forces were measured as a function of applied tool-work electrical potential. The cutting tool and workpiece were electrically insulated so that there was no current flow. Applied potential had no discernible effect on the cutting forces measured in the cutting of unextracted and extracted wet wood. 相似文献
5.
Bolesław Porankiewicz 《Wood Science and Technology》2006,40(2):107-117
Theoretical simulation of cutting edge wearing when milling wood and melamine coated particle board based on stochastical and analytical methods is presented. Abrasion, high temperature corrosion (HTC) and frictional wearing effects are discussed. Results of computations show good correlation between the observed and predicted wear rate for three different experiments. Relations between predicted tool wear rate from HTC, content (C
CP) and size (S
CP) of particles of hard mineral contamination and density (D) of cut material is also presented and discussed. 相似文献
6.
The surface quality of solid wood is very important for its effective response in manufacturing processes. The effects of feed rate, cutting depth and rake angle on surface roughness and power consumption were investigated and modeled. Neuro-fuzzy methodology was applied and shown that it could be useful, reliable and an effective tool for modeling the surface roughness of wood. Thus, the results of the present research can be successfully applied in the wood industry to reduce time, energy and high experimental costs. 相似文献
7.
Vahid Nasir 《Wood material science & engineering》2020,15(1):1-16
ABSTRACTSawing is the most common machining process and is present in both primary and secondary wood transformation sectors. The objective of this paper is to review how it is affected by different factors. The current challenges associated with various machining factors, process monitoring, and sensor selection were identified and explained. Consequently, four research challenges and technological gaps were outlined. (1) Contradictory results have been reported due to different cutting processes, wood species, measurement methods, and cutting speed range studied in literature, so special consideration needs to be taken when comparing results with those available in the literature. (2) Laboratory test conditions cannot yet fully represent the extreme cutting conditions in sawmills. More emphasis should be placed on those harsh industrial cutting conditions. (3) Research on wood cutting lacks multi-objective optimization approach, which suggests that sawdust generation should be simultaneously analysed with surface quality and power consumption. (4) Compared with metal cutting, little research has been conducted on wood sawing monitoring using an artificial intelligence approach, which should be prioritized in designing adaptive control systems. Combining intelligent monitoring and multi-objective optimization approaches should pave the way for controlling the sawing process so higher surface quality and cost efficient machining is achieved. 相似文献
8.
This paper studies the problem of high energy waste in the course of the wood fiber processing in the wood-based panel industry.
In the light of the energy economy principle, the cutting theory on the micron and long-slice wood fiber was put forward.
In this paper, by means of analyzing the power waste in traditional processing, a series of analytical measures, such as,
cytology, super precision work theory and fiber processing, and so on were utilized in the micron wood fiber formation process,
and the cutting conception of the micron and long-slice wood fiber was put forward. Accordingly, the study of the micron and
long-slice wood fiber was put into the microstructure study. This paper scientifically explains the reasons why the traditional
wood fiber processing consumes more energy and the fiber quality low. In an example, the cutting power on the micron and long-slice
wood fiber was calculated, which was compared with the traditional cutting power. The result showed that the energy waste
by machining at micron is much lower than by heat grind and the high quality and long-slice wood fiber was gained. Thus, a
revolutionary step was taken in the paper-making and wood-based panel industry of China.
__________
Translated from Scientia Silvae Sinicae, 2006, 42(3): 44–46 [译自: 林业科学 2006, 42(3): 44–46] 相似文献
9.
The aim of this study was to determine whether artificial ultraviolet (UV) light sources are able to imitate properly the
photodegradation of wood caused by sunlight. In this study, wood specimens were irradiated with a xenon lamp and a mercury
lamp. The xenon light simulated sunlight only in the case of long-term irradiation. The photoinduced yellowing of wood was
faster and greater in the case of short-term exposure to xenon light than that caused by sunlight. The number of UV light-generated
carbonyl groups absorbing infrared light around 1700 cm−1 showed good correlation with photoinduced yellowing. On the other hand, mercury light did not simulate sunlight. However,
the mercury lamp, as a strong UV light emitter, can be applied to determine the valid limits of the Kubelka–Munk (K-M) equation.
Our results show that the K-M equation cannot be applied to determine the absorption properties of the sample if the values
of the K-M units exceed 50. 相似文献
10.
Wim Willems 《Wood Science and Technology》2014,48(3):483-498
By expressing wood moisture content data as a function of adsorption energy, an interesting scaling capability is obtained, wherefrom the general hydrostatic pressure and temperature dependence of wood moisture content is determined. The scaling law is fully consistent with the thermodynamics of swelling. It can be used to transform room condition sorption isotherms to other temperatures and hydrostatic pressures, provided that the wood matrix is not irreversibly modified. A special procedure is suggested for the case of an irreversibly changing wood matrix, as in thermal modification and thermo-hydro-mechanical treatments. Using the present scaling theory, several fundamental aspects of wood moisture sorption are explained, such as the absence of a significant quantity of strongly bound wood moisture, the internal stress generation by sorption hysteresis in the wood cell wall, and the reason for the reversible disappearance of the sigmoid shape of the sorption isotherm at higher temperature. The results of this research may be useful (a) for transformation of known sorption data to other conditions, notably where in situ moisture measurements are difficult to perform and (b) to quantify the effects of internal stresses in the ultrastructure of the cell wall on moisture content. 相似文献
11.
Dr. W. M. McKenzie 《Wood Science and Technology》1991,25(5):397-401
Summary In spite of the obviously important role of friction in the wood cutting process, there has been little application in wood machining practice of true friction coefficients obtained from rubbing tests. Friction coefficients were measured during slow rubbing of incense-cedar blocks at two moisture contents on surfaces of saw steel, high speed steel and tungsten carbide. The coefficients were used in an orthogonal model of cutting to estimate the optimum rake angle for the planing of incense-cedar, and some evaluation of the estimate was made using data from cutting experiments reported elsewhere.The author wishes to thank Charles Berolzheimer, Director, The California Cedar Products Company Research Department, for his support of this work, and Richard Lemaster, University of California Forest Products Laboratory, for provision of facilities and assistance in that laboratory 相似文献
12.
滥伐林木案件的诉讼争议在于对采伐枯死林木行为性质的界定,司法实践中法官直接将林业法规用于刑事审判的做法没有考虑到刑法的实质入罪要求,不当扩大了本罪的规制范围.刑法第345条第二款保护的法益是国家的森林管理制度和生态环境中可以利用的森林资源,而枯死林木并不属于可利用的森林资源,因此应从本罪保护的法益出发,结合刑法的立法目... 相似文献
14.
The orientation of wood fibers and the resulting surface roughness of radiata pine are studied during a peripheral milling
with acoustic emission control. Studies were undertaken in machining process for radiata pine, where a surface quality problem
appears when cutting is not well controlled. It is known that acoustic emission signals are a good monitoring element of the
surface roughness with different cutting conditions. Previous studies have shown that changing cutting conditions affects
acoustic emission signals; these variations are related to surface roughness and chip formation. The purpose of this study
is to evaluate and quantify the surface quality and the consumption of cutting energy in radiata pine with differing grain
angles, and to determine the relationships of grain angle with acoustic emission signals in order to better optimize cutting
conditions. 相似文献
15.
J. H. Heering 《Agroforestry Systems》1995,30(3):341-350
The forage, wood and seed production of sixSesbania sesban accessions was assessed under irrigated conditions for two cutting frequencies and heights. Control trees were left uncut to measure their seed production potential. The trial was conducted over an 18-month period. The fastest growing accession produced almost 10 t/ha total dry matter (DM) after six months of growth, 40% of it being leaves. Total DM yield was higher at the six-month cutting interval compared to the three months' interval with yields between 25–42 t/ha/year. Some accessions could not sustain their high level of production but showed drastic drops in yield after repeated cutting. In general leaf DM production increased with increased cutting height. When cut at 150 cm the DM leaf yield at the three-month cutting interval ranged form 9.7–18.2 t/ha. More plants survived at the three-month cutting frequency. Seed yields varied considerably between accessions (0.02–1.56 t/ha at the six months' interval). After 18 months of undisturbed growth the trees yielded 36.5–83.7 t/ha total DM comprising 21% leaves. Fresh wood biomass ranged between 56.4–138.0 t/ha and seed yields 2.7–6.6 t/ha. 相似文献
16.
Mats Ekevad 《Journal of Wood Science》2005,51(5):455-461
Distortions due to moisture changes during drying or in service are a major problem for construction timber. Twist, caused
mainly by the cylindrical geometry, the orthotropic nature of the wood material, and the tendency of the wood fibers to grow
in a spiral around the stem, is often regarded as the most detrimental distortion of sawn timber. There is a need for a basic
mechanical understanding of how the twist distortion arises and also a need for a simple formula to predict the amount of
twist distortion. In this article such a formula is proposed, and theory and experimental data that indicate the validity
of the formula are shown. The first term in the formula is a modification of a traditional expression which is proportional
to the mean value of the spiral grain angle in the cross section in question. The second term in the formula is new and is
proportional to the gradient of the spiral grain angle, and this term normally counteracts the first term so that a stud with
a left-handed spiral grain might achieve a right-handed twist. Linear elastic finite element method (FEM) results and comparisons
with experimental data show that the formula works well and that linear FEM calculations exaggerate the twist, which is probably
partly due to nonlinear effects. The formula could be used to predict the twist of sawn timber from measured spiral grain
angles on the log surface. 相似文献
17.
On the frequency dependence of the modulus of elasticity of wood 总被引:2,自引:1,他引:2
D. Ouis 《Wood Science and Technology》2002,36(4):335-346
This short note reviews the reasons for the frequency dependence of the Modulus of Elasticity, MOE, of wood. It has in fact
been reported in several publications on wood that depending on the technique used in the test experiment, the value of the
MOE depends to some degree on the frequency at which it is evaluated. The frequency ranges used are namely zero frequency
in the case of static bending, audio frequencies when using mechanical vibrations or sound radiation and finally ultrasonics.
The results from implementing these three different techniques show that the lowest value that may be obtained for the MOE
occurs when using the static mode, and thereafter increases with increasing frequency. This property of increasing dynamic
MOE with frequency is shared by all solid materials, and finds its theoretical explanation in the Kramers-Kronig relations.
Dispersion in conjunction with the notion of complex MOE permit to establish the relation between the real and the imaginary
components of the MOE, i.e. respectively the dynamic and loss moduli. Due to the mathematical difficulties encountered in
using the exact expressions, approximations are necessary for applications in practical situations. Hence, an improved version
of the Zener model for viscoelasticity, which has lately been proposed by Pritz (1999), is presented. With some assumptions,
and under which excellent agreement has been obtained with the exact theory, this model is used for predicting the viscoelastic
properties of wood.
Received 2 October 2000 相似文献
18.
Bolesław Porankiewicz Piotr Iskra Jakub Sandak Chiaki Tanaka Karol Jóźwiak 《Wood Science and Technology》2006,40(8):673-682
Dulling of high-speed steel (HSS) cutting tools after milling five wood species has been analyzed. The wood investigated varied in mineral contamination, high-temperature corrosivity (HTC) and density (D). Experiments performed proved that up to date methods for evaluation of mineral contamination in wood should be improved. A new pipe-like form of mineral contamination particles was evidenced. The correlation between the presence of 3D aggregates of silica in wood and high content of K and Ca in the ash was established. Employing multivariable theoretical simulation method, the combined effect of mineral contamination, HTC and wood density on the tool dullness appeared to be a reasonable explanation of the results obtained. 相似文献
19.
通过适当的化学改性反应如酯化、醚化等,可以使木材转化为热塑性高分子材料。这些热塑性材料可单独或与合成高聚物按比例混合热压加工成型为各种板材或其他成型产品,这对扩大木材的加工利用途径、充分利用木材加工剩余物、提高木材利用率等都具有十分重要的意义。本文介绍了酯化、醚化木材的主要方法,产品的特点,以及今后木材及纤维素酯化、醚化的发展方向。 相似文献
20.
Miloš Ivković Washington J. Gapare Aljoy Abarquez Jugo Ilic Michael B. Powell Harry X. Wu 《Wood Science and Technology》2009,43(3-4):237-257
Development of optimal ways to predict juvenile wood stiffness, strength, and stability using wood properties that can be measured with relative ease and low cost is a priority for tree breeding and silviculture. Wood static modulus of elasticity (MOE), modulus of rupture (MOR), radial, tangential, and longitudinal shrinkage (RS, TS, LS), wood density (DEN), sound wave velocity (SWV), spiral grain (SLG), and microfibril angle (MFA) were measured on juvenile wood samples from lower stem sections in two radiata pine test plantations. Variation between inner (rings 1–2 from pith) and outer (rings 3–6 from pith) rings was generally larger than that among trees. MOE and MOR were lower (50%) in inner-rings than in outer-rings. RS and TS were higher (30–50%) for outer-rings than inner-rings, but LS decreased rapidly (>200%) from inner-rings to outer-rings. DEN had a higher correlation with MOR than with MOE, while MFA had a higher correlation with dry wood MOE than with MOR. SLG had higher significant correlation with MOE than with MOR. DEN and MOE had a weak, significant linear relationship with RS and TS, while MOE had a strong negative non-linear relationship with LS. Multiple regressions had a good potential as a method for predicting billet stiffness (R 2 > 0.42), but had only a weak potential to predict wood strength and shrinkage (R 2 < 0.22). For wood stiffness acoustic velocity measurements seemed to be the most practical, and for wood strength and stability acoustic velocity plus core density seemed to be the most practical measurements for predicting lower stem average in young trees. 相似文献