CNC Knowledge: ABS when the machine tool moves randomly

There are two common reasons why the machine tool moves randomly: 1. It is a problem with the metric and imperial systems. When some people enter the parameter search, they press the NO.SCR softkey, but the result is INPUT, which causes parameter #0 to change to metric and inch, causing the machine to move randomly- tool. 2 means the manual absolute ABS switch is activated. Some are in the machine tool control panel buttons and others are in the system software control panel.

1. Advantages and disadvantages of manual absolute value on/off function

The absolute value manual switch is used to select whether to add the amount of movement of the manual operation (JOG feed and handwheel feed) to the current position of the workpiece coordinate system by turning the absolute value knob manually to ON and OFF. At the same time, a detection signal is output to indicate whether the manual absolute value in the CNC is ON or OFF.

In actual processing, the manual absolute value on/off function is often used. If used well, it can make the processing operation simpler and more convenient; if used incorrectly, it often causes seemingly strange or serious problems that lead to tool collision. Similar issues mentioned above are often encountered during debugging and maintenance, but the factor of manually enabling/disabling absolute value is often easily overlooked.

Positive impact: For example: during rough machining, sometimes the feed amount is too much/less. At this time, you can insert a manual operation through this function to subtract/add the manual movement distance to the current position of the. coordinate system of the workpiece, thus avoiding the need for realignment of knives, etc. Negative effects are more common than positive effects. Since manual operations are often involved in processing; some machine tool manufacturers do not directly make this function a button on the control panel, but often use the K address or switch on the software control panel to set the function signal to 0 or 1, the values Manual absolutes are therefore often disabled inadvertently, causing problems. This factor is often easily overlooked.

For example: the manual absolute value is turned off accidentally or inadvertently (the operator is unclear and presses the software control panel randomly. During processing, it is necessary to check the processing status of the part, otherwise the tool is damaged and). must be replaced. At this point, manual operation is involved. After the operation is completed, “knife collision” accidents often occur or if machining continues after reset, the coordinates will be inexplicably incorrect;

2. Manual absolute value on/off function

NO and OFF of the manual absolute value are switched by 0 and 1 of the *ABSM signal (G6#2). At the same time, the MABSM signal (F4#2) can be used to detect the status of the manual absolute value signal.

Note: *The ABSM signal is active at a low level.

1 When manual absolute value is activated and is interrupted by manual operation during automatic operation:

Figure 1 Manual absolute value ON

Before a block is completed, insert a manual operation to move a certain distance. Whether it is an absolute value or an incremental command, the position of the machine tool tool in this block will be translated into the amount of manual operation.

The translated tool position in subsequent blocks will remain unchanged until the absolute value command block appears. After translation, if it is still an incremental command, the end point position will be offset by the amount of manual movement, and the current position display includes this offset amount.

2 When manual absolute value is deactivated, automatic operation is interrupted by manual operation.

Figure 2 Manual absolute value OFF

In automatic mode, if manual mode is inserted before a program segment is completed or terminated, then at the end of that program segment and at the end point of the next program segment, whether it is a absolute value instruction or an incremental value instruction, The position of the machine tool will be translated by the amount of manual movement. Once the operation is completed, the displayed value of the current position is the final programmed value, as if no manual insertion had been performed, but in fact the tool position has been translated.

3. Summary:

From the above, it can be seen that when the manual absolute value is turned off, the appearance is easily deceptive, and it is very easy to cause problems such as knife collision. Additionally, when the ladder diagram handles this function, the conditions that trigger the G signal are often hidden and difficult to find. Therefore, when dealing with issues such as tool collisions and coordinate changes, it is recommended to consciously consider the manual absolute value factor.