In the VPS, basic parameter settings such as zero return speed, creep speed, etc. can be made in the parameter table. Its dedicated positioning language (cod command) and sequential language make it easy to program. The following is a brief introduction to several code instructions that are closely related to this control.

The DRV is a high speed positioning command. The DRV command is used during the straight line feed. This command assigns the displacement to the target based on the independent X and Y axis settings. The amount of displacement and the amount of velocity can be set by both direct and indirect methods. Writing numbers directly to the unit is a direct way to set them up.

Here, the control amount is indirectly specified, the displacement amount is stored in the D100 and D101 units, and the operation speed is placed in D102 and D103. LINE is a linear interpolation instruction. During the formation of the bending angle, the table and the bending plate act simultaneously, and linear interpolation is performed, and a bending arc is formed due to the mechanical obstruction of the bending mold, and the bending tube is thereby produced. This command uses two simultaneous paths to move the machine to the target position. In the example given, the displacements of the X and Y axes and the vector velocity are set using the directly specified method.

The m code command is used to drive various auxiliary devices that assist in positioning operations (such as clamping, master, mandrel movement, half retreat, feed car up and down, left and right movement, etc.). Reading the m code into the programmable controller can be used to drive the auxiliary device. The buffer memory associated with the m code is shown.

When the m code is driven, the m code on signal is turned on and the m code number is stored in the appropriate special data register. End the drive auxiliary device and set the m code off signal. The positioning unit reads the m code off signal and performs the next operation. At the same time, turn off the m code on signal as shown.

Communication between the positioning unit and the programmable controller In order for the PLC and the positioning unit to complete the automatic control of the CNC bending machine, communication between the two must be realized. By using the FROM/TO instruction of the programmable controller, the buffer memory inside the positioning unit can be communicated with the PLC to exchange information between the two.

The FROM instruction reads the contents of the buffer memory into the PLC. The TO instruction reads the contents of the programmable controller into the buffer memory. As shown. The buffer memory number is represented by "#", and one dot is composed of 16-bit data. The contents of the buffer memory BFM#20 that are directly related to the elbow control. Each bit of buffer memory #20 is closely related to the motion of the motor. Assume that the X axis is forward rotation and M104 is ON at this time. The PLC writes M104 into the positioning unit through the TO command, M9004 is ON, and the X axis starts to rotate in the forward direction. Similarly, the FROM command can read the current value of the BFM of the positioning unit into the PLC. As shown.

The display is a touch screen screen. In the screen, three basic parameters of feeding, rotating and bending are required. The parameters are set on the touch screen first, and the set data is written into the preset address, that is, writing. Into the CPU of the PLC. The data is also written to the positioning unit using the FROM/TO command, and the machining process follows these parameters.

First, set a data register unit to store the displacement and speed. Use the TO command to write the speed to the positioning unit. In the VPS, when using the code language to set the speed or displacement, you only need to use the same buffer memory number. For example, in the high-speed positioning command in the above figure, the displacement of the X-axis is placed in #100 of BFM, and the speed is set in #102. Then the program is implemented as shown.

In the code language, the programming is as follows: code00(DRV)xDD100; the displacement is specified by D100 and D101 (32-bit data) fxDD102; the speed is specified by D102 and D103 (32-bit data) through the TO instruction, each required for the elbow action The parameters are written into the positioning unit, and the bending machine performs various linear feeding, space rotation and bending operations according to the data in the positioning unit, and bends the high-precision bending tube.

When the m code is used, after an action is completed, the m code is opened, and the m code is read into the PLC by the FROM instruction. The PLC turns off the m code and rewrites the positioning unit with the TO instruction, so that the program can continue to be executed downward. By turning off the m code, the driver of the auxiliary device is successfully completed, and the program is completed step by step according to the pre-programmed, as shown.

In summary, various parameters of the machining are written into the PLC through the man-machine interface, and the parameters are transmitted to the positioning unit by using the FROM/TO command of the programmable controller, and each one is executed according to the preset settings of the program. Action, complete the entire process.

Conclusion In the control system of CNC tube bending machine, PLC completes the timing control of the bending machine action, which can fully consider the sequence action and constraint relationship between each process. The positioning module is responsible for positioning control, and completes speed control, linear interpolation and the like.

(Finish)

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