Principles and methods of tool alignment?

The concepts of programming origin and machining origin?

Programming origin is the origin of programming parts according to machining patterns, which is also the origin of programming coordinate system. ?

When the NC machine tool runs the program for automatic machining, the trajectory of tool movement is controlled by the coordinate values given by the program. The reference system of this coordinate value is called machining coordinate system, and its coordinate origin is called machining coordinate origin. ?

After the parts are positioned and clamped in the machine tool, the position of the corresponding programming coordinate origin in the machine tool coordinate system should coincide with the machining origin of the workpiece. When programming, the programmer needs to select the programming origin and establish the programming coordinate system according to the part drawing, and use the instructions in the program to specify the position of the programming origin in the machine tool, that is, the machining origin of the workpiece, and establish the machining coordinate system of the workpiece. ?

Principle of knife alignment?

For CNC machine tools, the relative position between the tool and the workpiece must be determined before machining, which is realized by tool point alignment. Tool alignment point refers to the datum point that determines the relative position between the tool and the workpiece through tool alignment. The tool alignment point is often the machining origin of the part, which can be located on the machined part or at the position where the fixture has a certain dimensional relationship with the positioning datum of the part.

The principle of selecting cutter points: (1) makes programming simple; (2) It is easy to align and determine the position of the machining origin of parts; (3) convenient and reliable inspection during processing; (4) It is beneficial to improve the machining accuracy. ?

When determining the machining origin with the tool alignment point, it is necessary to "align the tool". Tool alignment refers to the operation that "tool position" and "tool alignment point" coincide, and "tool position" refers to the positioning reference point of the tool. For turning tools, the tool position is the tip of the tool. The purpose of tool alignment is to determine the absolute coordinate values of the tool alignment point (or workpiece origin) in the machine tool coordinate system and measure the tool position deviation value of the tool.

When using a variety of different tools to process the same workpiece, the relative coordinate values from the tool point of different tools to the reference point of the workpiece are different when the tool changing position is unchanged, which requires that the program can run normally when different tools start processing at different starting positions. In order to solve this problem, the CNC system of machine tools is equipped with the tool calibration function. It has the function of tool correction. As long as the position deviation of each tool relative to a preselected benchmark tool is measured in advance and input into the specified group number of the tool parameter correction column of the numerical control system, the tool position deviation can be automatically compensated in the tool path by using the T instruction in the machining program. The measurement of tool position deviation also needs to be carried out through tool alignment.

How to correct the knife?

In NC machining, the basic methods of tool alignment are manual tool alignment, instrument tool alignment, ATC tool alignment and automatic tool alignment.

The basis of manual tool setting is to set the tool by trial cutting parts, and the tool setting method of "trial cutting-measurement-adjustment" is adopted. Manual tool setting takes up a lot of machine time, but it is widely used in economical NC machine tools because of its simple method and few auxiliary equipment. Using the tool setting instrument to set the tool requires the auxiliary equipment of the tool setting instrument, which is expensive, but it can save the tool setting time of the machine tool and improve the tool setting accuracy. Generally used in CNC machine tools with high precision requirements. ATC tool alignment still has a certain tool alignment error, because it operates the tool alignment mirror and the tool alignment process is still manual. Compared with previous tool setting methods, automatic tool setting reduces tool setting errors and improves tool setting accuracy and efficiency. However, the CNC system must have the auxiliary function of automatic tool detection, and the system is complex, so it is generally used in high-end CNC machine tools. ?

Manual tool setting method for economical CNC lathe?

GSK928CNC system is the second generation CNC system developed by guangzhou cnc Equipment Factory. Taking GSK928 CNC lathe as an example, the specific operation method of manual tool setting is explained. ?

Simple knife setting process?

In manual mode, you can align the tools in the following order to obtain the tool offset. (1) Enter the main menu and enter manual); Mode; ?

(2) Select the reference point for tool alignment (the point of the tool tip is easy to reach and observe); ?

(3) Select a knife as the benchmark knife, such asNo.. 1 cutter, and type the command T 10 at the position where the cutter can be changed (select No. 1 knife without bias);

(4) Move the tool rest, move the tip of the reference tool to the tool alignment reference point, press the "COMMand comm" key to display the command menu, execute the NEWXZ command (set new system coordinates), and set the system coordinates to (0,0);

(5) Press the "comm" key and execute the T.SIZE command (set the tool offset with system coordinates), so that the tool offset value corresponding to the reference tool can be set to (0,0);

(6) Move the tool rest to the position where the tool can be changed, and change the No.2 tool with T20 instruction; (7) Move the tool rest to align the tool tip with the tool setting reference point; (8) Press the "comm" key, execute the command T.SIZE, and set the tool offset value corresponding to the tool as the current system coordinate value (only the tool offset value); (9) Repeat steps (6) to (8) to obtain tool deviation values of all tools. ?

If the optical tool alignment instrument is used, the center line of the tool alignment instrument can be used as the basic point of tool alignment, so that more accurate tool deviation value can be obtained. Trial cutting and knife alignment process?

(1) Use the "command command" and the T. test function to set the tool offset?

In manual mode, try to cut the tools in the following order to obtain more accurate tool offset. (1) Clamping workpieces and tools; ?

② Enter the manual mode; ?

(3) Select the reference knife (such as 1No. knife) and change the knife with the instruction of T 10; ?

(4) move the tool rest to make the tool close to the end face of the workpiece, open the end face of the spindle car, and take the new end face as the reference position in the Z axis direction;

⑤ The length of lathe excircle is 5 ~ 10 mm, and the spindle does not retract when it stops running. Measure the diameter value of the position in the X direction and the distance from the reference point in the Z direction, as shown in figure1; ?

⑥ Press "COMMand comm" and execute the T.TEST command (set the cutter offset with the size obtained from trial cutting). Display: TxTEST(x is the current tool number)?

X- enter the diameter value measured along the X axis at the trial cutting position X 1 z-enter the trial cutting length in the Z direction (distance from the reference position) Z 1.

The second line prompts BY (indicating whether it is a benchmark knife)?

Press the "Y" key, and the system will set the cutter offset according to the input value (cutter offset number = cutter number); ?

⑦ Change tools, and repeat ⑦ ⑦ to get all tool offsets (according to step ⑦, input X and Z values, and the second prompt will change to Y, and press the "Y" key, and the system will set the tool offsets according to the input values.

(2) Use "parameter param" and T.SIZE functions to directly input the tool offset value to complete the tool offset setting. (1) Clamping workpieces and tools; ② Enter the manual mode; ?

(3) Select the benchmark knife (such as No.65438 +0 knife) and change the knife with the command of T 10;

(4) Turn the end face, retract the tool in the X direction, execute the command of NEWXZ, set the system Z coordinate to 0, and keep the X coordinate unchanged;

⑤ When the excircle of the car is 5 ~ 10 mm, retract the cutter in the Z direction, execute the command of NEWXZ, and set the X coordinate of the system to 0, and the Z coordinate remains unchanged; ⑥ Press the "param" key, select the parameter T.SIZE, and modify the tool offset value of 1 to X0 and y0; ⑦ Move the tool rest to the position where the tool can be changed, and change the No.2 tool with T20 instruction; ?

⑧ Move the tool rest to align the tip of the tool with the end face of the workpiece, as shown in Figure 2(a), and write down the Z coordinate Z2 at this time; Then aim the tip of the knife at the excircle, as shown in Figure 2(b), and write down the X coordinate X2 at this time.

Accord to that method in step 6, the tool offset value of the No.2 tool is modified to X2Z2；; ?

Pet-name ruby repeat ⑦ ⑧ You can modify the tool offset of the remaining tools and complete the tool offset setting of all tools. ?

2.2. 1 Setting method of machining program for workpiece machining origin

In general, the origin of workpiece processing should be specified in the program. The method for GSK928 CNC lathe to specify the machining origin of workpiece is to use G92 instruction in the format of G92XZ (both X and Z are absolute values), and then input coordinate values after X and Z, indicating the distance from the current position of the tool to the machining coordinate origin. The method of G92 instruction specifying the origin of workpiece processing is shown in Figure 3.

2.2.2 Determination of the origin of workpiece processing?

As can be seen from Figure 3, when the machining origin is set with G92 command, the position of the workpiece machining origin is closely related to the tool starting position. As long as the starting position of the tool is determined, the origin of the workpiece coordinate is also determined.

GSK928 CNC lathe determines the starting position of the tool by manual operation. ?

Take Figure 4 as an example, the center of the end face of the workpiece is the programming origin, and G92 instruction is used in the machining program; G92X 100Z5, change the programming origin to the workpiece processing origin, and determine the starting position of the tool. The specific operation steps are as follows:

(1) First, according to the program instruction, calculate the distance from the tool tip to the center of the end face of the workpiece as follows: the diameter direction X= 100 (diameter value) and the axial direction Z = 5；; ?

(2) Clamp the workpiece, start the spindle, move the tool rest to make the tool tip (reference tool) approach the end face slowly, as shown in Figure 4(a), and set the Z coordinate of the system to "0" by the above method; ?

(3) Try to cut the excircle, and the cutting length is about 10mm (convenient for measurement), as shown in Figure 4 (b); ?

(4) Set the X coordinate of the system to "0" by the above method, and then retract the tool to make the tool leave the workpiece;

(5) Stop and measure the outer diameter of the workpiece D 1 and calculate the value of 100-D 1. ?

(6) Move the tool rest to the coordinates X= 100-D 1, Z=5, as shown in Figure 4(c), which is the starting point of the tool. ?

After determining the starting position of the tool, you can turn to the program for automatic processing. When executing the program segment G92X 100Z5, the CNC system determines the center of the end face of the workpiece as the machining origin of the workpiece.