The English wheel , also known as the wheel engine , is a metal workman that allows craftsmen to form multiple curves of flat metal sheets such as aluminum or steel.
Video English wheel
Description
The process of using an English wheel is known as wheel . Panels manufactured in this way are expensive, due to highly skilled and labor-intensive production methods, but have key advantages that can flexibly produce different panels using the same machine. It is a forming machine that works by stretching the surface and is associated in action against the beating process of the panel. Used where low-volume curved compound panels are required; usually in coachbuilding, car restoration, framework of spaceframe racing cars that meet regulations requiring sheet metal panels to resemble mass-produced vehicles (NASCAR), prototype cars and aircraft components. Production of UK wheels is at the highest level in the production of low volume sports cars, especially when more easily formed aluminum alloys are used.
Where large volumes of panel production are required, the wheels are replaced with press machines that have much higher capital costing and longer development times than British wheels, but every panel in the production process can be produced in any case. seconds. These costs are financed for a larger production run, but the stamp press is limited to one panel model per die set. The English wheel model shown is operated manually, but when used on thick sheet metal as for hull, the machine may be powered and much larger than shown here.
Maps English wheel
Construction
The machine is shaped like a capital letter and covered in "C". At the end of C, there are two wheels. The wheel at the top is called rolling wheel , while the wheel at the bottom is called anvil wheel . (Some references refer to the wheel by their position: top wheel and undercarriage .) Anvil wheels usually have smaller radii than the rolling wheel. Although larger engines exist, roller wheels are typically 8 cm (3 in) or less, and are usually 25 cm (9 inches) in diameter, or less.
The rolling wheel (above) is flat in cross section, while the anvil wheel (bottom) is vaulted.
The depth of the C-shaped frame is called throat . The largest machine has a 120 cm (48 inch) throat size, while the smaller engine has a throat size of about 60 cm (24 inches). C stands vertically and is supported by a frame. The size of the throat usually determines the size of the largest metal sheet that can be placed by the operator in the machine and works easily. On some machines, the operator can rotate the top wheel and enclose 90 degrees to the frame to enlarge the maximum size of the workpiece. Because the engine works with a certain amount of pressure between the wheels through the material, and as the pressure changes as the material becomes thinner, the lower jaw and cradle of the frame that hold the anvilla roller can be adjusted. It can move with hydraulic jacks on machines designed for steel plates, or jackscrew on machines designed for sheet metal. As a thin material, the operator must adjust the pressure to compensate.
Frame design is the most important element of this simple tool. For the most part the wheels have changed very little since the 19th century. The early English machines (as opposed to the American version), such as Edwards, Kendrick, Brown, Boggs, and Ranalah, etc., have a cast iron frame. These wheels, made in the 19th century, have Babbitt metal bearings, making it difficult to push and pull metal when operated at high pressure. Then, when the ball bearings begin to be used, the machine becomes more suited to hard and thick material, like the 1/8 "steel.Although it has the advantages of cast iron, this machine has less than half the stiffness (Young's modulus) of steel and sometimes should be replaced with steel when a rigid frame is required Steel frames made of solid cuttings, or frames constructed from cut and welded plates, are common designs Steel pipes, generally of square parts, have been used for frame machine wheels for 30 years lastly, in the US in particular, where sheet metal shaping has become a hobby as well as a business.The tube-framed machine is quite cheap and available either as a built-in kit or can be easily constructed from the plan, the rigid tubular frame has completely triangulated external truss bracing, which is most effective on thinner or softer materials, such as 20 ga steel or 0.63 "aluminum. The cast frame machine, as illustrated, is still available.
A well-equipped machine has a variety of anvil wheels. Anvil wheels, such as dolls used with a hammer in the beating panel (also known as the foundation) should be used to match the desired crown or curvature of the workpiece.
Operation
The engine operator passes the metal sheet between the anvil wheel and the rolling wheel. This process stretches the material and causes it to become thinner. As the material stretches, it forms a convex surface on the runway wheel. This surface is known as the "crown". The high crown surface is very curved, the low crown surface slightly curved. The rigidity and strength in the workpiece surface are provided by the high crown region. The radius of the surface, after work, depends on the degree that the metal in the center of the workpiece extends relative to the cut edge. If the center is too long, the operator can recover its shape by pushing the edges. Rotating edges has the same effect in correcting the wrong-shape because it is too widened in the center, just as it shrinks directly into overcrowded areas by using shrinking heat or the shrinking Eckold type. This is because the edge holds the shape in its place. Decreasing the edge before the wheel helps shape form during the wheel, and reduces the amount of stretching and thinning required to reach the final shape. The shrinkage process reduces the surface area by thickening the sheet metal. Shrinking by hand is harder to do and slower than stretching using a panel or wheel beater, as this should only be used when absolutely necessary. The aluminum sheet should be annealed before being towed for rolling over the mill during the hardened production work.
Strength and stiffness are also provided by edge treatments such as flanging or wiring, after the creation of the correct surface contour has been achieved. The flange is essential for the finished surface form which is possible to make multiple panels by shrinking and stretching the flange only, without using surface stretching or shrinking altogether.
Adjustments
The pressure of the contact plane, which varies with the radius of the dome on the runway wheel and the adjusting screw pressure, and the number of drive trajectories determines the extent to which the material extends. Some operators prefer the foot adjuster so that they can maintain a constant pressure over various thicknesses of sheet metal to spruce up, with both hands free to manipulate the workpiece. This adjuster style also helps to blend the thinner edges of the taller crown, with a relatively unbroken low crown area. The downside of the foot adjuster is that it can block highly-curved panels, such as the mudguards cycle type used on motorcycles, pre-WW2 sports cars, and open-wheeled cars like the Lotus/Caterham 7.
To overcome this problem, some wheeled engines have a hand adjuster near the bottom of anvil yoke (also known as a wheel holder) so that such a panel can curl underneath it unhindered. This type of machine typically has a diagonal 'C' shaped frame that curves lower to the floor, with a hand-operated adjuster near the base-wheel stand instead of the horizontal and vertical hand length shown in the image above. The third type of adjuster moves the top wheel up and down with a static left bottom ground.
Shaping
At each stage of fabrication, operators must constantly reference the shapes they want to reproduce. This may involve the use of paper templates, template sections (made using paper or thin metal sheets), station money, shaper, profile gauge, profile template and of course the original panel. A wheel machine equipped with a quick release lever, which allows the operator to drop the wheel of the runway away from the top wheel so that the workpiece can be quickly removed and inserted without losing pressure settings, is a great time-saver during this process.
The operator must have patience to painstakingly pass through the area on the sheet to form the area correctly. They can make an additional pass by different wheels and in different directions (at 90 degrees for simple double arch shape, for example) to achieve the desired shape. Using the correct pressure and proper grounding wheel shape, and an overlapping accurate overlap pattern (or really overlapping with a low crown base) makes using the machine as art. Too much pressure produces wavy, damaged, and stressful parts - while too little pressure makes the job take too long.
Localized braking on one part of the panel is likely to cause mis-formation in adjacent areas. The cultivation or stretching of an area causes the adjacent area to sink, and correcting which may affect the area further than the original working panel. This is because the tension in the panel caused by the stretch affects the panel shape further than might be imagined. This means the operator has to work in a large area of ​​the panel, fixing these side effects while causing more side effects that should also be corrected.
The key to producing the right shape is to have the precise amount of metal surfaces stretched across this wider area. If this is achieved, it is possible to "move" the metal with minimal extra stretching, filling low dots with metal from high points. This smoothing is almost like planishing using a medium pressure setting, but it is still heavier than that used for planishing. It is a time-consuming and tortuous iterative process, which is one of the most difficult and skillful parts of the wheel. As panel sizes increase, the work involved and difficulty levels increase disproportionately. This is also the reason that very large panels can be very difficult to do and are made in sections. The high panel/crown portion may need to be annealed because the metal working hardening, which makes it brittle, can not be worked and can be cracked.
After obtaining the correct basic shape with the correct amount of metal in the right place, the worker must unite the high crown edge of the crown with a low crown field, so that the contours of the surface change from one to the other smoothly. After this, the final stage of the wheel involves very light pressure to climb the surface to make it smooth and cohesive. This stage does not stretch the metal but it moves the metal that already extends around it, so using the minimum runway pressure and the width of the runway as much as possible with the panel form, is very important.
Usually, only a small high crown panel, (like a repair section) or a large low crown panel (like a roof), is made intact. The large low crown panel requires two skilled craftsmen to support the weight of the panel.
Limitations
The five main limits of the machine are:
- The thickness of the sheets that the machine can handle
- Set workpiece in the depth of the machine's "throat"
- The size of workpiece that the operator can physically handle
- The risk of over-stretching/thinning of panels or crown parts is too high (Not good has the right contours if the metal is too thin and weak.)
- As the size of the panel or section increases, the work involved and difficulty levels increase disproportionately
This limitation is the reason why large high crown panels such as wings and fenders are often made in many parts. The pieces are then welded together usually with one of two processes. TIG welding (Tungsten Inert Gas) produces less heat distortion, but produces louder and more brittle welds that can cause problems when plotting/smoothing by hand, or on a wheel machine. Oxy-acetylene weld joints do not have this deficiency, provided they are allowed to cool to room temperature in the air, but produce more heat distortion. Panel connections can be achieved by using autogenous welding - ie welding without fill bars (Oxy-acetylene or TIG process), this is useful when finally smoothing the welding joints as it reduces the amount of filing/grinding/coating required or virtually eliminates it altogether. It also, more importantly, reduces the heat distortion of the surface contours, which must be fixed on wheels or with hammers and dolly.
Completed
The final panel fabrication process, having achieved the correct surface contour, is some type of edge treatment, such as flanging (sheet metal) or wire edging. It completes and strengthens the edges. Usually, there is too much or too little metal in the flanges, which pulls the panels out of shape after the flange is rotated - so it should be stretched or shrunk to improve the shape of the surface. This is most easily done by using a shrinking and stretched Eckold, but it can be done by using heat shrinking or cold shrinkage, by slipping and hitting the folded metal into itself, or by using a hammer and dolly that shrink. Stretching or flange shrinkage requires a correct hammer and dolly profile. The hammer and the doll must match the desired flange shape at the point of contact through the flange, (known as ringing the dolly) with the hammer. Many jobs shrink or stretch to harden leads and can cause cracks and tears. While this can be welded, it is much better to coat the metal before it happens to restore its working ability.
The English wheel is a better tool for skilled craftsmen for applications with low knobs than manual hammers. Planishing manually using puppet and slapper files or planishing hammers, once the hammers form very labor-intensive. Using a pear-shaped hammer and sandbag to stretch the metal sheet (sink), or by raising the stake, speeds up the crowning of the higher part. A pneumatic hammer or power hammer is still faster. The English wheel is very effective when used for planishing, (for which it was originally patented in England), to complete a smooth finish after this process.
References
Further reading
- The American View of the British Wheel by Kent White.
- Advanced Techniques for the British Wheel by Kent White.
- Ron Fournier. Metal Fabricator's Handbook . ISBN: 0-89586-870-9. Ã,
- Ron Fournier. Sheet Metal Handbook . ISBNÃ, 0-89586-757-5.
- Tim Remus. Fabrication of Ultimate Metal Sheets . ISBN: 0-9641358-9-2. Ã,
- Tim Remus. Advanced Metal Fabrication . ISBN: 1-929133-12-X. Ã,
- A. Robinson, W.A. Livesey. Body Repair . ISBN: 978-0-7506-6753-1.
External links
- Art of Fine Metal Shaping, by Kent White. Articles are reprinted from Experimenter Magazine
- Ron Fournier Metal Q & amp; A at fournierenterprises.com
- Justin Baker Traditional British Cast Iron Wheel
Source of the article : Wikipedia
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