Three-point method to prevent machine collision

Then the last article, we focus on how to prevent the collision machine fire three ways, these are the professional experience of the personal experience of the operator, I hope for your help.

"One make three adjustments"

After the program input is completed, the tool parameters and the workpiece coordinate system are "told" to the tool by the tool setting. In the process of the knife, to prevent the collision caused by the following factors or produce scrap: First, the installation of the tool, that is, too high or too low tool installation, the tool tip is not aligned with the workpiece rotation center; Second, cutting test measurement error, especially Is the inner hole diameter measurement; Third, mistakes in the parameter input process, for example, the T1 tool parameters mistakenly input to the position of the T2 tool parameters; Fourth, the choice of cutting dosage is unreasonable, the workpiece surface roughness is poor; Fifth, the programming input size Method, generally in the majority of the dimensional deviation of the unified programming, the direct input of the basic size, rather than a unified size, enter the size deviation of the median; Sixth machine (rail) there is a problem.

"A complement" is a good tool, the tool parameters in the X offset value compensation to give 0.5 ~ 1mm or more (outside the contour processing as an example), the general Z-offset size. FANUC CNC system can directly use the display under the "+" softkey to compensate 0.5 ~ 1mm, Siemens 802C can also use the G158 zero offset instruction to give up the size, and then perform automatic processing.

After processing the first piece of "three tone", accurate measurement of the size of each step, the size of the first error and so on, and calculate the difference or margin, as the basis for tool offset compensation, and then "a" tool parameters, Compensation value and then fill it back. For the size of the first error and knife compensation parameters can not be resolved size "two transfer" program coordinate values to ensure the processing size. According to the processing of magnification to adjust the situation "Triad" cutting amount (spindle speed, feed rate, depth of the knife). And then perform one or two finishing cycle, so that both to prevent the production of waste, but also to ensure the quality of processing.

The above is the author in the numerical control car teaching practice and experience. In programming, should carefully read the machine tool manual or related programming information. Before performing automatic machining, the simulation functions provided by the numerical control system should be fully utilized to grasp the correctness of the simulation trajectory and the machining contour. The problems existing in the programming should be detected and corrected in the simulation test as much as possible.

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"A stop" to be precise in the automatic processing should be suspended several times. Through the pause, the operator can have enough thought to observe and compare the tip position and the screen coordinate display. Especially when the chip is wound on the workpiece or the tool, the user can press the cycle stop key to prevent the operation from making mistakes due to panic.

"Three-point line"

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The "three-point line" is the key element in the process of determining the processing route. The "three o'clock" is the starting point, the starting point of the contour and the ending point of the contour. Line is the outline to be machined (as shown). Reference Farnak system, for example, outside the contour processing, the starting point is the starting point of the cutting tool, the programming is G00 quickly reach the point after the start of G01 processing. Many students in the use of G71, G72, G73, G92 and other circular instructions, starting point set up unreasonable, as a result of the tool causes the workpiece and workpiece damage, the risk of danger. Therefore, set the starting point must be correct, the starting point must be outside the scope of the workpiece blank, X coordinate greater than the blank 2mm, Z coordinates beyond the blank end 2 ~ 3mm. If the blank size error is relatively large, the point should be further away from the blank range, to prevent the tool G00 fast forward collision with the workpiece.

The starting point of the contour corresponds to the P parameter in the G71, G73 machining cycles. In this program segment, only the X coordinate is written and the system default Z coordinate. In the implementation of processing, the tool should be out of the vertical knife, or in the system will occur during program error alarm.

The end point of the contour corresponds to the Q parameter in the machining cycle. The X coordinate of the point should be greater than or equal to the blank diameter, but it must be smaller than the X coordinate of the starting point of machining. Otherwise, the cutter or even touch accident may occur when G71 retracts. The end point Z coordinate should be at the far left of the outline.

The relationship between the start and end of the contour and the starting point. The start and end of the contour Z to the left and right, X to a look up and down. Starting point is outside the blank range, X is higher than the end of the contour and the starting point of the contour is flush with the Z direction. No matter what kind of CNC system or different cutting cycle, the position of these three points must be taken seriously, careful analysis, to prevent the processing problems.

The "first line" is the connection from the start point to the end point. The G01, G02 and G03 instructions are mainly used to make the corresponding machining program according to each individual geometric element (ie, straight line, slash line and arc) to form the machining program The various procedures that block. In the process of preparation of the work, to use the minimum number of blocks to achieve the processing of parts, so that the program can be concise, reduce the chance of error, improve the efficiency of programming. Because CNC lathe devices generally have the function of linear and circular interpolation operation, in addition to non-arc curve, the number of segments can be formed by the geometry of the parts that the process route to determine the various programs, this time should consider using the least program Section preparation principle. Select the correct G command, the outline of the shape of the Z direction must be one-way increase or decrease (bore machining), X direction, the general use of G71 machining cycle, so the outline of the shape should be stepped one-way increments. Through the simulation can be observed G71 cycle does not recognize the cavity, no matter how deep the concave is the last knife out. If you use a sharp knife, part of the small backstroke groove depth of less than 2mm, can be processed directly, or must be separated from the cavity, separate programming, a separate knife, processing. If the workpiece contour has a straight step, note that in the G71 cycle, the Z direction generally does not leave a finishing allowance in order to prevent the knife or the knife from being cut during the finishing cycle G70. If the step size accuracy is high, 0.2 ~ 0.3mm allowance can be reserved in the contour programming, and the step surface processing alone can ensure the dimensional accuracy and surface precision of the workpiece.

  As a beginner if you can master these points of knowledge, then you can reduce the probability of damage to the machine, to avoid precision and other technical issues and losses are not allowed.