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How to avoid safety problems in small machining centers

How to avoid safety problems in small machining centersHow to avoid safety problems in small machining centers

1. The origin of the workpiece coordinate system set by the programmer during programming should be outside the workpiece blank, at least on the workpiece surface.

Under normal circumstances, the origin of the workpiece coordinate system can be shot anywhere, as long as this origin has a certain relationship with the origin of the machine coordinate system. However, in actual operation, if the command is zero or close to zero, the tool will directly point to zero or close to zero. During milling, the tool will run towards the base surface of the table or fixture; during turning, it will run towards the base surface of the chuck. In this way, the tool will penetrate the workpiece and point directly at the reference plane. At this time, if it moves fast, an accident must occur.

FANUC system general setting: when the decimal point is omitted, it is the minimum input unit, usually Hm. When the decimal point is omitted, the input value will be reduced by one thousandth, and at this time, the input value will be close to zero. Or, for other reasons, the tool should have left the workpiece but actually did not leave the workpiece and entered the workpiece. In this case, the zero point of the workpiece coordinate system should be set outside the workpiece or on the base surface of the table (or fixture), and the result will be different.

  2. Programmers and operators must be careful about decimal points when writing programs.

The FANUC system is the smallest setting unit when the decimal point is omitted, while most domestic systems and some systems in Europe and America, when the decimal point is omitted, is mm, which is the calculator input method. If you are used to the calculator input method, there will be problems on the FANUC system. Many programmers and operators may use both systems to prevent problems due to decimal points.

In order to make the decimal point eye-catching, the isolated decimal point is often written in the form of “0” when programming. Of course, when the system is executed, the zero after the decimal point of the value is ignored.

3. When adjusting the workpiece coordinate system, the operator should set the reference point outside the physical (geometric) length of most tools, at least on the tool point of the longest tool.

For the workpiece coordinate system on the workpiece installation drawing, the operator obtains the offset by setting the machine coordinate system on the machine tool. That is, the operator sets a reference point on the machine tool, finds the size between this reference point and the zero point of the workpiece coordinate system set by the programmer, and sets this size as the workpiece coordinate system offset.

On a lathe, the reference point can be set at the center of rotation of the tool holder, the tip of the reference tool, or another position. If no additional motion is added, the zero commanded by the programmer is the reference point of the tool holder (machine tool) and moved to the programmed Ling position. At this time, if the reference point is set at the rotation center of the tool post, the tool post must collide with the workpiece. In order to ensure no collision, the reference point on the machine tool should be set not only outside the tool holder, but also outside all the tools. In this way, even when the tool holder is equipped with a tool, the reference point will not collide with the workpiece.

On a milling machine, the reference points of the X and Y axes are on the spindle axis. However, the reference point of the Z axis can be set at the spindle end or at a point outside the spindle end. If it is at the spindle end, when the command is zero, the spindle end will reach the zero position specified by the coordinate system. At this time, the key on the end of the spindle will collide with the workpiece: if a tool is installed on the spindle, it will collide with the workpiece. To ensure that there is no collision, the reference point on the Z axis should be set beyond all tool lengths. Even if no other movement is added, the reference point will not hit the workpiece.

4. When adjusting the tool length offset, the operator should ensure that the offset value is a negative value.

When the programmer instructs the tool length compensation, the T code command is used for turning, and the G43 command is used for milling, that is, the tool length offset value is added to the command value. In the direction of the machine tool coordinate axis, the direction of the tool moving away from the workpiece is specified as positive, and the direction of the tool moving closer to the workpiece is negative. The operator adjusts the tool offset value to a negative value to instruct the tool to move to the workpiece. When the commanded tool approaches the workpiece in the program, in addition to the commanded value, the offset value of the tool is added. This additional value is moved toward the workpiece. At this time, in case this value is missed, the tool will not reach the target point.

To make the tool offset value a negative value, when specifying the reference point on the machine tool, it must be set beyond all tool lengths, at least at the tool position (point) point of the reference tool.

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