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Skills in CNC Press Brake Machine Operation
When machining the first workpiece, the machine tool should use the single-step working state for trial cutting. When the machine program calls a new tool or grinding wheel, the tool should be calibrated first to check whether the program action is correct.
When the workpiece is processed, try to take one clamping to complete the workpiece processing; if the second clamping of the workpiece is required for measurement or other reasons, it must be ensured that the positioning and processing benchmarks of the second clamping and the first clamping are unified. . If the automatic positioning device of the machine tool is adopted, it is necessary to maintain the consistency of the measurement speed of the automatic measurement system. When testing the machining accuracy of the workpiece, it is best to complete it on the machine tool, which can reduce the positioning error of the secondary clamping. In addition, when the machine tool is processing some parts of the workpiece, when the precision of its dimensional tolerance is high, the operator needs to perform an accuracy check after each machining is completed, and then go to the next position of the workpiece after the inspection is passed; if the workpiece is The shape of a certain part is synthesized from two or more directions, then the processing in each direction will affect the position or shape tolerance of the shape of the part, so the one that has less impact on the accuracy of the workpiece should be processed first. direction, and then re-process the direction with higher workpiece tolerance requirements, and finally repeat the processing, and finally approach the required accuracy. If the workpiece cannot be measured using a standard measuring instrument on the machine tool, and the workpiece cannot be removed from the machine tool for measurement, otherwise the machining accuracy of the workpiece can be affected, then special calipers, plug gauges, gauges and other means can be used to measure the workpiece. Inspection, if the software of the machine tool itself has a measurement function, then the machine tool itself can be used to measure the workpiece. After the entire workpiece is processed, a comprehensive inspection of the workpiece is carried out.
For the processing of batches of workpieces. After the initial program debugging is completed, the machining program needs to be optimized. The basic principles of optimization are as follows: to ensure the premise of machining quality, optimize cutting parameters, such as machining speed, tool or grinding wheel speed, lateral feed, machining depth, etc.; optimize machining steps, optimize machining benchmarks, improve machining efficiency, and use high Longevity of tools or grinding wheels, reducing the number of tool changes or grinding wheel corrections; establishing a reasonable mathematical model of the machining program, editing effective and reliable programs, reasonably setting the allowance and times of roughing and finishing, and using appropriate forming tools or grinding wheels to improve efficiency. , to ensure the processing quality has a more significant effect.
To ensure the processing quality of the workpiece to be processed, the following aspects should be paid attention to: the machine tool should be warmed up for a period of time during processing, the thermal balance of each mechanical axis of the machine tool should be maintained during operation, and the temperature of the workpiece to be processed should be kept as stable as possible during the machining process. Heat and cold balance of work heads, machine tool spindles, screw guides, grating scales, tool chucks or grinding wheel adapters. If the machine tool uses cooling oil and coolant, its temperature should be kept constant. The temperature of the coolant is one of the important factors that affect the accuracy of the workpiece machining. The cooling system of the machine tool ensures the constant temperature of the coolant.
Generally, the factory needs to be shut down at night, and the machine tool needs to be turned on the next day, so the machine needs to be warmed up every day before working. In order to improve the utilization rate of machine tools, there are two existing methods to realize machine tool processing. One is to modify the original program slightly after starting the machine, and make a compensation amount far away from the workpiece in all the processing procedures. Then, during the processing, the machine tool changes the correction value according to the measurement results when the machine tool is processing. When the machine tool is in thermal equilibrium, the correction The value does not need to be changed. Another method is to machine the parts with large tolerances on the workpiece for a period of time after starting the machine, and then wait until the machine tool reaches thermal equilibrium after a period of time, and then machine some positions on the workpiece with higher tolerance requirements; or use the machine tool first. Rough machining is carried out, and after the machine tool work reaches thermal equilibrium, the finishing machining of the workpiece is carried out.
For a workpiece with multiple datums and dimensions that require high precision. Then, there is a datum on the workpiece that only defines one or two dimensions, but the position with higher dimensional accuracy is required. For the part with multiple dimensions of the same datum, the part with the highest precision should be processed first, and then the part with the highest precision should be processed. low position. Because the workpiece is prone to produce waste when the machine tool is processing high-precision parts, the rest of the workpiece can not be processed, which saves processing costs.
In short, the basic principles of processing: first roughing, remove the excess material of the workpiece, and then finish machining; avoid vibration during machining; avoid thermal denaturation of the workpiece during machining. There are many reasons for the vibration, which may be caused by excessive load, resonance between the machine tool and the workpiece, or insufficient rigidity of the machine tool, or passivation of the tool or grinding wheel. We can reduce vibration by the following methods: reduce the lateral feed and machining depth, check whether the workpiece clamping is reliable, increase the speed of the tool or reduce the speed to reduce the resonance, and check whether it is necessary to replace a new tool.