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| 2. |
- Ekevad, Mats, et al.
(författare)
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Lateral cutting forces for different tooth geometries and cutting directions
- 2012
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Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 7:3, s. 126-133
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Tidskriftsartikel (refereegranskat)abstract
- Lateral (sideways) cutting forces were measured for 6 different tooth geometries when cutting green spruce and pine heartwood. The teeth were intended for use on circular saw blades for the rip sawing of logs. The 6 tooth geometries were designated straight, pointed, bevelled, rounded, trapezoidal and hollowed out. Cutting speed was 15 m/s, feed per tooth was 0.3 mm and the cutting directions were 90°–90° (rip sawing) and 90°–0° (milling), with two different variants of growth ring angles for each direction. The tools were tested in sharp conditions, in dull conditions and in a dull condition with a corner broken off. All lateral forces were small when cutting with sharp teeth, except for the rounded and bevelled teeth. Lateral forces increased with wear, except for a period of initial wear where the lateral forces were reduced. High wear resulted in greater lateral forces, most probably due to unsymmetrical wear. Growth ring direction did not generally affect lateral forces. The teeth with acute corners, which were the straight and hollowed out tooth, were most sensitive to a broken off corner. The lateral forces in the cases of wood cutting at 90°–90° increased less with wear compared to the 90°–0° cases.
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| 3. |
- Ekevad, Mats, et al.
(författare)
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Wear of teeth of circular saw blades
- 2011
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Konferensbidrag (refereegranskat)abstract
- Measured wear data is presented for 3 different carbide grades. The data were collected during rip sawing wood with a double arbour saw. The purpose of the test was to determine the suitability of different grades for sawing frozen timber. A set of circular saw blades of diameter 350 mm was equipped with teeth comprised of 3 different cemented carbide grades, denoted A, B and C. These 3 grades were chosen out of 6 grades in an earlier preliminary laboratory test. Grade A was a relatively soft and tough standard grade (K1C=17, HV30=1150) normally used in sawmills in winter conditions for frozen wood, grade B was harder and more brittle (K1C=11, HV30=1600) and grade C was even harder and more brittle (K1C=9.5, HV30=1950). The double arbour saw (with vertical arbours) was equipped with 6 saw blades (3 on each arbour) for cutting 2 centre boards and 2 side boards. The 6 saw blades with different teeth were mounted in a mixed manner on the arbours, and after sawing a number of logs the wear of teeth was measured. After some time the blades were removed, inspected, ground and used again for sawing. The thickness of boards was also measured and the standard deviation was calculated.The results show cutting edge radii as a function of the number of logs sawn and also the standard deviation of the thickness of the sawn boards. Grade A had the highest wear and grades B and C the lowest wear. There was no significant edge damage during the tests. Grade C did not suffer problems of chipping from cutting edges and was found to be suitable for sawing frozen timber. The thickness standard deviations were constant at about 0.2 mm, and not a function of the number of logs sawn.
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| 4. |
- Ekevad, Mats, et al.
(författare)
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Wear of teeth of circular saw blades
- 2012
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Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 7:3, s. 150-153
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Tidskriftsartikel (refereegranskat)abstract
- Measured wear data is presented for three different carbide grades. The data were collected during rip sawing wood with a double arbour saw. The purpose of the test was to determine the suitability of different grades for sawing frozen timber. A set of circular saw blades of diameter 350 mm was equipped with teeth comprised of three different cemented carbide grades, denoted A, B and C. The double arbour saw was equipped with six saw blades for cutting two centre boards and two side boards. The six saw blades with different teeth were mounted in a mixed manner on the arbours, and after sawing a number of logs the wear of teeth was measured. The thickness of boards was also measured and the standard deviation was calculated. The results showed that grade A had the highest wear and grades B and C the lowest wear. There was no significant edge damage during the tests. Grade C did not suffer problems of chipping from cutting edges and was found to be suitable for sawing frozen timber. The thickness standard deviations were constant at about 0.2 mm, and not a function of the number of logs sawn.
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| 5. |
- Ekevad, Mats, et al.
(författare)
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Wood-chip formation in circular saw blades studied by high-speed photography
- 2012
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Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 7:3, s. 115-119
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Tidskriftsartikel (refereegranskat)abstract
- Films of wood-chip formation were captured with a high-speed camera during rip sawing of wood with a circular saw blade. The saw blade diameter was 400 mm and the rotational speed was 3250 rpm. The saw blade had four teeth with rake angles of 0°, 10°, 20° and 30° to ascertain the influence of different rake angles. Wooden boards were cut along the side so that the camera could record the cutting sequence without any interference from material between the cutting teeth and the camera. Tests were made for green, dry and frozen green pine boards, for both counter-cutting and climb-cutting cases. In addition, some Mozambican wood species were cut. The films, recorded at 40,000 frames s−1, show the cutting sequence along the trajectory of the tooth in question and the creation of the wood chip. Details such as the compression of the wood chip in the gullet, the movement of the wood chip inwards and outwards in the gullet and finally the exit from the gullet are visible. The chip size and chip movement depend strongly on the rake angle and on whether the wood is green, dry, frozen or unfrozen.
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| 6. |
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| 7. |
- Guo, Xiaolei, et al.
(författare)
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Cutting Forces and Chip Morphology during Wood Plastic Composites Orthogonal Cutting
- 2014
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 9:2, s. 2090-2106
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Tidskriftsartikel (refereegranskat)abstract
- The effect of chip thickness, rake angle, and edge radius on cutting forces and chip morphology in wood plastic composites (WPCs) orthogonal cutting was investigated. Three types of WPCs, Woodflour/polyethylene composite (WFPEC), wood flour/polypropylene composite (WFPPC), and wood flour/polyvinyl chloride composite (WFPVCC), that were tested exhibited different behavior with respect to the machinability aspects. The cutting forces of WFPVCC were the highest, followed by WFPPC and WFPEC. The most significant factor on the parallel cutting force of these three types of WPCs was the chip thickness, which explained more than 90%, contribution of total variation, while rake angle, edge radius, and the interactions between these factorshad small contributions. The most significant factor on the normal cutting force of WPCs was also the chip thickness, which accounted for more than 60% of the total variation. The chips produced included long continuous chips, short continuous chips, flake chips, and granule chips when cutting these three types of WPCs.
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| 8. |
- Guo, Xiaolei, et al.
(författare)
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Effect of average chip thickness and cutting speed on cutting forces and surface roughness during peripheral up milling of wood flour/polyvenyl chloride composite
- 2015
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Ingår i: Wood research. - 1336-4561. ; 60:1, s. 147-156
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Tidskriftsartikel (refereegranskat)abstract
- Wood flour/polyvinyl chloride composite (WFPVCC) is a kind of composite material that, over the years, is becoming more popular in constructions applications. In this work, cutting forces and machined surface roughness were studied during peripheral up milling of WFPVCC under different average chip thickness which was obtained by adjusting rotation speed and feed rate at both high and low speed cutting conditions. The results indicated that cutting forces components, parallel force (F-x) and normal force (F-y) greatly varied during the cutting process. Maximum F-x, maximum F-y and surface roughness increased with the increase of average chip thickness. Maximum F-x and maximum F-y at high speed cutting conditions were lower than that at low speed cutting conditions at a same average chip thickness. The machined surface roughness at high speed cutting conditions was better than that at low speed cutting conditions at a same average chip thickness. When meeting the requirement of certain surface roughness, higher cutting speed can allow higher chip thickness and then decrease the tool wear than lower speed cutting condition. Maximum negative F-y had great impact in machined surface roughness. Machined surface roughness increased with the increase of maximum negative F-y. Thus, high speed cutting conditions not only increase the machining productivity, but also decrease machined surface roughness during the peripheral up milling of WFPVCC.
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| 9. |
- Guo, Xiaolei, et al.
(författare)
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Tool wear and machined surface roughness during wood flour/polyethylene composite peripheral upmilling using cemented tungsten carbide tools
- 2014
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 9:3, s. 3779-3791
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Tidskriftsartikel (refereegranskat)abstract
- The effect of sharpness angle on tool wear and the effect of tool wear on machined surface roughness were investigated in wood flour/polyethylene composite (WFPEC) peripheral up-milling using cemented tungsten carbide (TC) tools. It was shown that nose width and edge recession increased with increasing feeding length. During the milling process, the wear of the nose width was smallest for the tool with a sharpness angle of 45°, followed by tools with sharpness angles of 55° and 65°. The wear of edge recession was highest for the tool with a sharpness angle of 45°, followed by tools with sharpness angles of 55° and 65°. The nose width increased with increasing sharpness angle, the edge recession decreased with increasing sharpness angle, and the machined surface roughness increased with increasing sharpness angle after a feeding length of 40 m. The nose width had a positive effect on the machined surface roughness, and the machined surface roughness increased with increasing nose width. The edge recession had little effect on the machined surface roughness. The clearance face roughness of the worn tool increased with increasing sharpness angle. The analysis of the SEM micrographs and EDS of the clearance face of the worn tool showed that the wear mechanisms of the cemented tungsten carbide tool were oxidation and abrasion in the range tested during cutting. Thus, a slight wear of the edge recession is gained in exchange for a lower machined surface roughness by decreasing the sharpness angle.
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| 10. |
- Li, Rongrong, et al.
(författare)
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Investigation of Glueline Shear Strength of Pine Wood Bonded with PVAc by Response Surface Methodology
- 2015
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 10:3, s. 3831-3838
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Tidskriftsartikel (refereegranskat)abstract
- The effects of process parameters (adhesive spread, press time, and applied pressure) on the response parameter (shear strength) of pine wood bonded with PVAc were studied. Response surface methodology was applied for design of experiments and for analysis of results. A mathematical model was developed to establish the relationship between the process parameters and response parameters. The results showed that the major factors were adhesive spread and applied pressure. The shear strength increased as the adhesive spread and applied pressure increased within certain ranges.
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