Improve the precision machining of thin flexible technical approach – flexible sheet machining – metal industry
In the production of elastic deformation of the most easy to detect thin parts in place, and found that precision can meet the design requirements, but found its size and remove the form and position tolerance has undergone great changes, some even far beyond the design to the extent permitted. The reason is: easy to thin parts of the stiffness of elastic deformation is weak, coupled with high precision workpiece datum, the plane is lower, the workpiece by the atmospheric pressure due to suck or press and hold the clamping force by the clamping force of the effects caused by the workpiece deformation, deformation state in the process, although the reign of the workpiece detected dimension and shape tolerance can meet the design requirements, but took it down after the workpiece deformation recovery, the size and shape and position tolerance, great changes have occurred , so beyond the scope of the design requirements.
Production of thin elastic deformation encountered in many vulnerable parts, such as the common Washer , Friction plate, plate of Spring , Sheet, flyer, and these poor rigidity, thermal problems, caused by clamping fixture easily deformed during processing will warp, which seriously affect the machining accuracy. Heat treatment of such parts and precision machining technology of fixture, that is to reduce clamping deformation and heat treatment of the workpiece deformation, deformation of the workpiece to reduce the final accuracy of the parts, thus ensuring the flexibility to thin parts of the machining precision of crucial importance. Another part of the reign of easy detection
elastic deformation of thin parts, found the workpiece size and geometrical tolerance and Machine tool Far from normal precision, this is because the cutting force to the workpiece when machining workpiece deformation occurred, leaving the cutting edge, the deformation caused by partial recovery.
Therefore, improving the accuracy and pre-finished components to reduce clamping deformation and reduce the cutting force components is easily deformed elastic sheets to improve the precision machining important steps.
2 sheets to improve flexibility in the technical means of precision machining
2.1 to reduce heat deformation, increase the size of the workpiece before finishing position accuracy
Requirements for mechanical properties of the higher parts, generally require heat treatment to improve the mechanical properties of the workpiece. However, quenching austenite into martensite when the volume to expand, with great organizational stress, combined with rapid cooling due to thermal stresses in a great internal stress, causing deformation during quenching, and even cracking. Easy elastic deformation for the thin part, because of weak rigidity, the deformation more. In order to improve machining accuracy, it must reduce the heat deformation. Designed to reduce heat deformation
Design components should be closely integrated with the process, attention to process conditions, as far as possible to reduce heat from the parts structure deformation.
Design components used in choosing the material should be as high carbon content or with high steel alloying elements, because the higher carbon content in general, including higher steel alloying elements, the end of the austenite into martensite the lower the temperature, the more retained austenite after quenching, quenching stress of the smaller, and thus the smaller the deformation. And hardenability of steel is good, generally use the oil quenching, the workpiece in oil cooling, slow cooling, thermal stress is relatively small, so small deformation cracking tendency.
Design artifacts, if no other effects, should maximize the end flange to increase the stiffness of parts.
School-based tooling design heat treatment immediately after quenching, tempering, will re-heating the parts after quenching austenite below the critical temperature, after holding for some time, cooled to room temperature. Design school-based tooling, the quenching of the workpiece into the school just type tooling fixation school type, and then into the furnace together with the workpiece temper and shape, so could well correct the deformation after quenching. The experiment confirmed that diameter Ø350mm, thickness of 3mm elastic surface components during heat treatment using school-based tooling, the deformation is 0.20mm, if not by school-based tooling, deformation will be greater than 1mm. The choice of clamping means
2.2 Parts finishing should be focused on considering clamping means, as far as possible parts to be processed in the state, consistent with its free state, that should avoid or reduce clamping deformation, suck or folder by as much as possible, top, pressure and other forms of clamping.
Pad elastic clamping block mode Elastic clamping body parts in the free state to locate and clamp. Positioning the workpiece and the tooling surface layer of uniform thickness between 0.5mm pad rubber, when the workpiece by the clamping force, the first rubber is compressed, the workpiece elastic deformation is small, which can be processed with higher accuracy Shape , release after the deformation. This method is suitable for high precision machining datum.
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