Bent Blade Research Articles

Analysis of blockage and wrapping by leaves in the cutting mechanism of a sugarcane leaf shredder

Sugarcane leaves are long and have high flexibility. A machine to pick-up, shred and return sugar cane leaves to the field has been designed. It consists of a roller which picks up leaves and feeds them into a cutting mechanism where they are then shredded. The working width of the cutting mechanism of the machine is less than the feeding width of sugarcane leaves and this can easily cause blockage and wrapping of the cutting mechanism. To address this issue, the blade roller of the machine was improved by adding anti-wrapping pipes and using bent blades. Based on a theoretical analysis of sugarcane leaves in different feeding states, it was shown that the structural parameters of the blade roller, wrapping length of sugarcane leaf and forward speed of machine were the key factors influencing blockage and wrapping. By simulating the cutting process of sugarcane leaves using LS-DYNA in two feeding states, the average displacement of sugarcane leaf elements in contact with the anti-wrapping pipes and bent blades was obtained. The simulation results showed that the average displacements of sugarcane leaf elements under two feeding states were greater when the blade roller had anti-wrapping pipes and bent blades, which indicated that the improved blade roller was more conducive to cutting sugarcane leaves. High-speed photography of the cutting process showed that cutting sugarcane leaves in the transverse feeding state was an improvement and only a small amount of leaves in the longitudinal feeding state were wrapped around, and adhered to the rotary blades and anti-wrapping pipes. However, there was little wrapping of the bent blades. The experiment showed that the average cutting rate and its standard deviation were 91.68% and 1.58% respectively, and the average wrapping rate and its standard deviation were 1.13% and 0.37%, respectively. • Cutting mechanism with bent blades and anti-wrapping pipes developed. • Three feeding states were identified for sugarcane leaves in cutting mechanism. • Bent blade and anti-wrapping pipe reduce blockage and wrapping in cutting mechanism. • Improved cutting mechanism enhance the performance of sugarcane leaf shredder.

Coat weight control in bent blade mode

Bent blade metering is the most common method used in board coating. As board machine speeds today have increased, new requirements have been set on blade geometry and accuracy of blade adjustments. A good understanding of the blade parameters and physical phenomena around the blade tip area is, therefore, necessary. Automatic coat weight profile adjustment using feedback from the coat weight measurement system is a great tool to improve the cross-direction coating uniformity and reel condition. In bent blade coating, however, the parameters for adjusting the cross-direction profilers need to be modified from those used in stiff blade coating. At high board coating speeds with bent blade, good coat weight control will require tuning of the blade parameters. To be able to reach a given coat weight at a high speed with a low tip angle, a high mechanical force is needed to control the high dynamic forces that are created in the blade tip area. The mechanical force can be increased either with a thicker blade or with a shorter free stick-out (i.e., shorter distance between the blade support bar and the blade tip). A higher tip angle can be used to decrease the dynamic forces to keep the coat weight in target; however, coating coverage and uniformity of the coating layer will then be reduced. Furthermore, blade wear is more severe at higher tip angles. For cross-direction profiling, a shorter free stick-out is suggested as a better approach than use of a thicker blade. The coat weight profile response and accuracy improves with a shorter stick-out as thinner blade with more flexibility can be used. Three alternative coat weight control methods for bent blade operation are discussed: blade load adjustment, beam angle adjustment, and load adjustment at constant tip angle. For effective coat weight cross-direction controls, the blade operating mode and parameters need to be chosen in accordance with the speed and coat weight range at which the coater is operating.

Reliance

Reliance Catherine Reid (bio) I back the tractor out of the barn, get down on my hands and knees, and study the way the mower is attached. Two familiar messages sound equally loud in my head: I can do this. And, Can I do this? One of the blades had come off earlier in the week, when Holly was mowing, in a terrible grinding and strewing of metal parts. And now, though I’d rather be at the river or working in the garden, I kneel instead in gravel, remove the cotter pins, and free the bolts holding the main pulley in place. After dragging out the mower, I flip it over, a turtle on its back, missing one of its legs. The other is badly bent, and both it and the one still attached are so dull and pitted it’s hard to tell how the edges sliced grass. I take off the second blade and rue that I don’t have an anvil or large vise. I make do with a maul and a concrete block, slamming the heavy hammer against the bent blade a few times. Then I push a block of wood into the shade for a stool, sit down with the blade clamped between my feet and start filing, diagonal strokes toward the edge, black metal slow to yield silver. As sweat gathers on my back, I think how much easier it would be to borrow a truck, take the tractor to a repair shop, and let someone else deal with grease and scraped skin. But something insists that I do this myself, something that won’t relax its hold on me, and while often I like the stance such independence affords, it’s a trait that has also gotten me into trouble. An hour or so later, the pieces back together, I start the tractor, engage the mower, and shift into gear. The tractor bucks and shudders, and I know I didn’t reshape the blade quite right, but this time nothing flies off and I can see cut grass in my wake. I circle the lower field and head home for a beer. [End Page 17] “Why did you learn how to do that?” the horse whisperer asks. We’re eating pieces of yellow sheet cake in a room full of prisoners, and the best I can manage is a shrug. He deserved something better. We were, after all, the team that won at Pairs for Chairs, our arms linked together as we raced for a seat each time the music stopped. Elbow to elbow, we had had to find the right balance between caution and roughness—yank too hard and it might be misconstrued; don’t yank hard enough and you might miss a chair. We kept from getting tangled in each other’s legs and were the only ones left sitting when the game came to an end. But finding a better answer than “because I’m a dyke” or “self-reliance is in my genes” or “I drink of the same waters as did Emerson and Thoreau” requires too much explaining. I’m still not even sure why I’m spending a weekend in prison with men convicted of violent crimes. I do know it’s a good program—the Alternatives to Violence Project—co-led by outside facilitators and inmates who have already gone through the training. My role is similar to that of the twenty-odd prisoners, except that I get to go home to my lover at night. Like the men, however, I had much to surrender at the main entrance, including autonomy and a driver’s license; unlike them, I didn’t have to strip or get orifices checked, and the metal detector’s sweep around my body was brief. When the first session finally began—some of the men having waited months for this—we sat in a circle and learned about the games we would play, the exercises we would do, the times we would pair up or talk as a whole group. Then we were off at a pace that seemed edgy and fast, the inmates white and black and Hispanic, teenaged and...