Effects of cutting parameters on cutting forces and surface quality of black spruce cants

The effects of rake angle, cutting direction, and depth of cut on cutting forces and surface quality of black spruce were evaluated. Cutting forces were measured during cutting at four rake angles (35°, 45°, 55° and 65°), four cutting directions (0°–90°, 15°–75°, 30°–60°, and 45°–45°), and three depths of cut (1, 2, and 3 mm). Torn grain, waviness, and roughness were evaluated. The results showed that as rake angle increased, cutting forces, torn grain, waviness, and roughness decreased. The lowest cutting forces and the best surface quality were obtained with 65° of rake angle. At this angle, cutting forces and surface quality were more affected by depth of cut than by cutting direction variations. Thus, as depth of cut decreased, the effects of cutting orientation on the cutting forces and surface quality decreased. The application of these results to the canting work of a chipper-canter is analyzed.     

Study on the normal component force in oblique cutting of wood

Based on a series of experiments, the relationships between normal component forces and oblique angles of cutting edge, and normal rake angles in oblique cutting of wood were studied. The experiments consist both of the 90°-0° and the 0°–90° oblique cutting situation. Each type of experiment includes two wood species and two kinds of thickness. Through the experiments, the rules of the effect of oblique angles of cutting edge and normal rake angles on normal component force were found out. The calculation methods of normal component force were studied by mathematical analysis.     

Influence of grinding direction and wheel translation on microsharpness of cemented tungsten-carbide tips

The attempt has been made to determine the grinding direction and the wheel translation which produce the best microsharpness for carbide-tipped tools, such as carbide-tipped saws. Other grinding variables considered were rake angle, grinding depths and diamond-grit size. The results suggest that the grinding direction should be adjusted to an angle of 45° or larger to the cutting edge and that the grinding wheel may be fed parallel to the plane of grinding, but should always be retracted perpendicular to it. Grinding direction in grinding the first face was found not to influence the microsharpness of the cutting edge.     

Effect of surface modification and knife penetration angle on the Quasi-Static Knife Penetration Resistance of para-aramid fabrics

The focus of this paper is to describe the effect of change in surface friction of single layer para-aramid (Twaron^®) square woven fabric and change in knife penetration angle on its Quasi-Static Knife Penetration Resistance (QSKPR). The surface friction of fabric was changed by depositing SiO₂ on its surface by using water glass as a precursor. Six different knife penetration angles (0°, 22.5°, 45°, 67.5°, 90° and 135°) were selected. Untreated and treated fabric samples were compared for change in QSKPR. It was observed that the deposition of SiO₂ on the surface of Twaron^® fabric increased the surface friction which resulted in the increase in QSKPR. The response of fabric against QSKPR changed from partial yarn cutting to individual yarn cutting in fewer steps and load was distributed to a larger area due to decrease in yarn slippage. The change in penetration angle changed the distance, knife cutting edge travelled to cut each next yarn(s) and when this distance increased, the QSKPR was reduced. The post-penetration image analysis of damaged fibres showed that the load distribution among warp and weft yarns was complementary and change in penetration angles changed the distribution of stabbing load among the warp and weft yarns. When yarns with higher tensile strength and less slippage were loaded, the fabric showed highest resistance to penetration. A QSKPR prediction model was also proposed at the end.     

金刚石复合片刀具磨损机理研究

选用平均粒度10微米的金刚石复合片制成刀具,对高硅铝合金（Al-30wt%Si）进行切削实验。通过扫描电子显微镜分析了工件的形貌以及金刚石刀具前后刀面磨损的微观形貌。其磨损程度与切削路程为线性关系,金刚石刀具的磨损主要是后刀面机械摩擦磨损以及前刀面的粘接磨损,而没有出现像立方氮化硼刀具的化学磨损以及月牙洼磨损。     

切削参数对人造板切削力影响的研究

通过对中密度纤维板和刨花板的闭式切削实验,研究了不同锯齿前角、切削厚度、切削速度等参数对切削力的影响规律。结果表明:主切削力和法向力皆随前角的增大而呈减小趋势;通常情况下,相同锯齿前角切削时,刨花板的主切削力和法向力皆比中纤板大。切削厚度对切削力的影响显著,主切削力和法向力均随切削厚度增加而增加。切削速度对切削力的影响相对较小,随着切削速度的增加,主切削力和法向力均略有减小。     

切削参数对竹材切削力影响的研究

研究了竹材切削不同刀具前角、切削量与切削速度对切削力的影响.刀具前角对主切削力的影响较为显著,随刀具前角的增大,所需主切削力明显减小.主切削力与切削量成正相关关系.切削速度对切削力的影响不大.     

用单位矢量法求刀具角度

用数学分析方法精确求解木材切削刀具的角度。在求解过程中,用单位矢量来代表刀刃线和刀面的外法线方向,简化了推导过程和计算公式。同时区分了刀刃在坐标平面上的投影角和刀面相对坐标平面的倾斜角,并用实例计算说明这两种角度有时差值较大。因此,精确计算刀具角度对提高木制品的加工精度,提高刀具的强度、寿命及锋利性是有意义的。     

Cutting forces in bandsaw processing of oak and beech wood as affected by wood moisture content and cutting directions

Cutting forces in bandsaw processing of oak and beech wood were measured at two levels of wood moisture content (about 12 % and FSP) for four cutting directions (90°–90°, 90°–0°, 0°–90° and 90°–45°). A constant cutting speed of 40 m/s and a feed rate of 20 m/min were applied. A piezoelectric dynamometer (KISTLER type 9257A) mounted on the carriage of the vertical bandsaw machine (ESTERER model EB 1400) was used to measure the parallel, normal and lateral cutting forces. Results revealed that all cutting forces depend on the wood moisture content and cutting direction. The greatest parallel force was observed for oak wood at 12 % MC for 90°–90° cutting direction (44 N/mm) whereas the lowest one was for beech wood at 30 % MC for 0°–90° cutting direction (20 N/mm). In contrast to the little change of lateral force at various cutting directions, the change in parallel force was significant.     

切削纤维板时表面涂层硬质合金刀具的磨损

对表面涂层硬质合金刀具切削高密度纤维板后的磨损状况分阶段进行了测量,并与普通硬质合金刀具进行了比较,结果表明,涂层刀具优于普通硬质合金刀具。在化学蒸汽涂层(CVD)和物理蒸汽涂层(PVD)两种涂层刀具中,后者的品质和耐磨性优于前者。     

Assessment of surface properties and solvent-borne coating performance of red oak wood produced by peripheral planing

Coating performance on wood could be affected for different aspects including the manner in which the surface is prepared. Peripheral planing is one of the most used machining processes in woodworking. Improving this process would allow to enhance coating performance. As a result, the effects of wavelength and rake angle on surface properties and coating performance were evaluated in an attempt to improve peripheral planing of red oak wood. Surface quality was assessed through roughness, scanning electron micrographs, and wettability analyses. The performance of a solvent-borne coating was measured by adhesion strength before and after accelerated aging. Surface roughness and energy components increased as rake angle increased. As wavelength increased, cell damage and surface roughness increased. Surfaces prepared with a rake angle of 25° had more cell-wall fibrillation, which was assumed to be responsible for increased surface energy and improved coating adhesion after weathering. Samples machined with this rake angle combined with a short wavelength resulted in the lowest loss of adhesion after aging and presented an acceptable level of surface roughness.     

Effects of cutterhead diameter and log infeed position on size distribution of pulp chips produced by a chipper-canter

Effects of cutterhead diameter and log infeed position on the mechanism of chip formation and size distribution of black spruce chips produced by a chipper canter were evaluated. Two cutterhead diameters (448.7 and 661.5 mm) combined with three infeed positions or vertical distance from the cutterhead axis to the bedplate on which the log was supported, were tested. The mean angle between the chipping rake face with respect to the grain (mean attack angle) was calculated for each infeed position. The nominal linear cutting speed was fixed at 23.5 m/s. Rotation speed and feed speed were adjusted to obtain a nominal chip length of 25.4 mm. Ninety-six logs were transformed under frozen and unfrozen wood temperatures. The high-speed images showed that the attack angle and temperature of logs (frozen and unfrozen wood) played an important role in the mechanism of chip formation. Within a knife cut, the images also showed that chip thickness was mainly defined by radial-longitudinal and in a lesser degree by tangential-longitudinal splitting ruptures. Furthermore, chip size distribution was also affected by the cutterhead diameter, attack angle, and temperature condition. Mean chip thickness decreased as attack angle increased for both cutterhead diameters, regardless of wood temperature condition. Further, frozen logs produced thinner chips than unfrozen logs (regardless of the cutterhead diameter and/or attack angle). The maximum amount of pulpable chips was produced during the fragmentation of unfrozen logs at the greater attack angle for both cutterhead diameters. These results give useful information to estimate changes in chip size distribution that could occur within the studied range of infeed positions (or attack angles) and cutterhead diameters.     

Reliability analysis of seam joints in square plain parachute canopy fabric

Performance of parachute continuously degrades due to opening shock and dynamic pressure acting on its various components after opening. During repeated use of parachute, degradation in tensile strength of canopy fabric plays an important role. Measurement of probability of successful operation of parachute in repeated use and under impact loading is possible through reliability analysis of its seam joints. Present study mainly concerned with the reliability analysis of the performance of square plain parachute canopy joined in parallel at different bias angle. The impact loading of the specimen degrades its tensile property and the extent of loss depends on its bias angle of stitching. However, the deterioration of performance in terms of tensile strength is more as compared to breaking elongation. Without subjecting any impact, specimen stitched at 0° and 45° have almost same breaking strength. However, impact loading degrades the tensile property of specimen with 45° bias angle to a greater extent as compare to specimen with 0° bias angle. As regards breaking elongation of specimen, the specimen stitched at 45° bias angles always exhibits highest value (even after impact loading) than the specimen stitched at other bias angles. The reliability analysis of seam joints shows that the specimen stitched at 0° bias angle is most reliable among other angles of stitching in terms of maintaining tensile strength for longer impact cycle.     

Performance of helical edge milling cutters in planing wood

A new design of a milling cutter with solid helical edge has been developed for improving the performance of cutting wood. Development of the new helical edge milling cutter with its geometries for planing wood has been followed by some research progresses. In this work, a conventional edge milling cutter and helical edge milling cutters were tested in planing spruce wood (Picea abies). The purpose of the research work was to investigate chip flow, power consumption, noise emissions, edge wear, and surface roughness characteristics of the helical edge milling cutters in planing spruce wood. Experimental results showed that the helical edges compared to the conventional edge milling cutter provide better chip flows with nearly axial direction and low flight velocity. Though the extreme helical edges up to 75° inclination angle generate comparable or slightly larger cutting power than the conventional edge, they considerably generate lower sound pressure level of up to 5 dB(A). The helical edge milling cutters are better in wear resistance, suffer less edge fractures, and produce better surface quality of planed wood than the conventional edge milling cutter.     

Inspecting anisotropy in wrinkle recovery angle of woven fabric

In this paper, the anisotropic wrinkle recovery properties of plain and twill fabrics are explored by studying the variations of the wrinkle recovery angle with sample orientation angle. Orientation angle is the angle measured counterclockwise from the weft direction to the sample’s long axis, that is, the crease direction. This study focused on inspecting anisotropy in wrinkle recovery to find more effective test angles for different woven fabrics. A dynamic wrinkle recovery tester was used to measure the recovery angles of specimens automatically which were cut in various directions. The trend of plain fabrics shows that its recovery angle generally increases at first and then decreases with the increase in the orientation angle. The trend of twill fabrics differs in folding ways. The experimental results revealed that the wrinkle recovery angles of the woven fabrics had the lowest values near the orientation angles of 0° and 90°, i.e. the warp and weft directions, and therefore these two traditionally used directions in the standard test method did not best reflect the wrinkle recovery yielded from both warps and wefts. The diagonal direction (45°) was proven to be the optimal orientation angle for a balanced plain fabric, while the two orthogonal directions, i.e. the twill direction and its perpendicular direction, were found to be more relevant for a twill fabric. Optimal orientation angles used to test the wrinkle recovery angle of a woven fabric should be associated with its structure.     

Minimizing dust emission during routing operation of rubberwood

The study evaluated airborne dust emission (0.1–10 µm) during the routing operation of Rubberwood (Hevea brasiliensis) in the furniture industry in South East Asia. It was found that the average chip thickness of 0.1 mm and wood moisture content of 12–14% minimized dust emission, while the cutting tool rake angle had little influence on dust emission. The study shows that adverse economic implications due to health hazards posed by airborne dust emissions during wood machining can be reduced by manipulating the average chip thickness and work-piece moisture content.     

Annealing effects on structural changes and thermal shrinkage of poly(lactic acid) draw-textured filaments

To control the thermal shrinkage of poly(lactic acid) draw-textured yarns, the annealing effects on structural changes and thermal shrinkage were investigated. Specifically, annealing temperatures of 100 and 160°C and annealing times of 10–50?min per every 10?min were investigated. Differential scanning calorimetry thermograms revealed that filaments annealed at 100°C produced double melting peaks due to crystal imperfections, while those annealed at 160°C for more than 30?min showed a single melting peak. Moreover, wide angle X-ray scattering revealed that annealing at higher temperatures led to better developed crystal structures. Although, the crystal structure developed by annealing birefringence indicated that average molecular orientation was not greatly affected. Yarns annealed at 160°C showed the least thermal shrinkage of 2%, while those annealed at 100°C decreased from 7.9–5.4% with increasing annealing time.     

Untersuchungen über den Einfluß der Feuchttemperatur auf den Verlauf der Hochtemperaturtrocknung von Schnittholz

Drying tests with 30 mm thick spruce board specimens at 110°C, 130°C and 150°C dry-bulb temperature and 65°C as well as 95°C wet-bulb temperature, respectively, showed that at 110°C dry-bulb temperature and 95°C wet-bulb temperature (110/95°C) drying of the green board specimens with edge grained annual rings (average initial moisture contentH _A=92%) from 70 to 8% moisture content needed 47% more time as at 110/65°C, and at 130/95°C it needed 9% more time as at 130/65°C, whereas the drying time at 150/95°C and 150/65°C was the same. In the case of green board specimens with flat grained annual rings (H _A=184%), drying from 150 to 8% moisture content at 130/95°C compared with 130/65°C took 25% longer, and at 150/95°C compared with 150/65°C it took 4% longer. Particularly noteworthy was that the drying time from 30 to 8% moisture content of the green board specimens with edge grained annual rings and of at room temperature predried edge grained specimens to 40% moisture content, was shorter at 130/95°C than at 130/65°C, resulting from larger excess pressures built up inside the wood; at 150/95°C also the drying time of the more permeable green board specimens with flat grained annual rings was shorter than at 150/65°C. Drying at 95°C wet-bulb temperature proceeded always more uniformly and with minor drying defects as at 65°C.     

Hydrophobic recovery of atmospheric pressure plasma treated surfaces of Wood-Polymer Composites (WPC)

In this study, the behavior of atmospheric pressure plasma treated surfaces of Wood-Polymer Composites (WPC) was investigated as a function of time and environmental conditions. The surfaces of injection molded WPC based on polypropylene (PP) and polyethylene (PE) were treated by a dielectric barrier discharge (DBD) and subsequently aged under various conditions. The wettability as an indicator for change of the composite surface was assessed using water contact angle. In addition, a calculation for half-time of the contact angles was developed to predict the time span which is needed for recovery of hydrophobicity. The results showed a major influence of temperature and time, whereas the humidity only at storing conditions of 60?°C and 75% relative humidity showed a distinct effect on the activated surface. The effect of DBD treatment was stable for more than one week in the climates 20?°C and 0% RH and 20?°C and 65% RH.     

Untersuchungen über den Einfluß der Feuchttemperatur auf den Verlauf der Hochtemperaturtrocknung von Schnittholz

Drying tests with 30 mm thick spruce board specimens at 110°C, 130°C and 150°C dry-bulb temperature and 65°C as well as 95°C wet-bulb temperature, respectively, showed that at 110°C dry-bulb temperature and 95°C wet-bulb temperature (110/95°C) drying of the green board specimens with edge grained annual rings (average initial moisture contentH _A=92%) from 70 to 8% moisture content needed 47% more time as at 110/65°C, and at 130/95°C it needed 9% more time as at 130/65°C, whereas the drying time at 150/95°C and 150/65°C was the same. In the case of green board specimens with flat grained annual rings (H _A=184%), drying from 150 to 8% moisture content at 130/95°C compared with 130/65°C took 25% longer, and at 150/95°C compared with 150/65°C it took 4% longer. Particularly noteworthy was that the drying time from 30 to 8% moisture content of the green board specimens with edge grained annual rings and of at room temperature predried edge grained specimens to 40% moisture content, was shorter at 130/95°C than at 130/65°C, resulting from larger excess pressures built up inside the wood; at 150/95°C also the drying time of the more permeable green board specimens with flat grained annual rings was shorter than at 150/65°C. Drying at 95°C wet-bulb temperature proceeded always more uniformly and with minor drying defects as at 65°C.