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Standard process steps of CNC machining process
Date: 2022-09-08
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The standard process of CNC machining is generally 7, and each process is required to be carried out in sequence. If it is not carried out in the order of the standard process of CNC machining center, it is easy to cause machine failure or personal safety, and the staff needs to pay special attention.

1. Ready to start

Every time the machine is powered on or reset after an emergency stop, the machine will return to the machine reference zero position (ie, return to zero), so that the machine has a reference position for subsequent operations.

2. Workpiece clamping

Before cleaning the surface of the workpiece, it should be cleaned first, and it should not be stained with oil, iron or dust, and the surface burrs should be removed with a file (or oil stone). The surface of the fixture must be ground and polished to make it flat and smooth.

The iron and nut must be firm and can clamp the workpiece reliably. For some small workpieces that are difficult to install, they can be directly clamped on the tiger head; the machine table should be clean, free of iron filings, dust and oil; at the four corners of the workpiece, the middle If the workpiece is too large, a high angle needs to be added in the middle. According to the size of the drawing, use a ruler to check whether the length and width of the workpiece are qualified.

When clamping the workpiece, install it according to the programming instructions to avoid the possibility of encountering the fixture at the processing part and the processing head.

After the workpiece is placed on the horn, it is necessary to pull out the reference surface of the workpiece according to the requirements of the drawing. For workpieces that have been processed on both sides, check whether the perpendicularity is acceptable. After the workpiece is drawn, the nut must be tightened to prevent the clamp from being unstable and the workpiece from being displaced during processing; then pull the table once, and correct the error after confirming the error.

It is necessary to check whether the verticality is qualified. After the workpiece is drawn, the nut must be tightened to prevent the clamp from being unstable and the workpiece from being displaced during processing; then pull the watch once, and correct the error after confirming that there is an error.

3. Number of workpiece contacts

The number of contact heads can be used to handle the reference zero for clamping the workpiece, and the contact heads can be photoelectric and mechanical. There are two types of contact number: unilateral contact number and unilateral contact number. The steps of contacting are as follows: photoelectric static electricity, and the mechanical speed is 450-600rpm.

Manually move the X-axis of the worktable in the middle of the touch, so that the touch head touches one side of the workpiece. When the touch head just touches the workpiece and the red light is on, set the relative coordinates of the point to zero; the X-axis touches the other side of the workpiece and touches The relative coordinates of the moment when the head touches the workpiece. Subtract the head diameter (i.e. workpiece length) from its relative value.

Divide the relative coordinate number by 2, the value is the middle value of the X axis of the workpiece, then move the worktable to the middle value of the X axis, and set the relative coordinate value of the X axis to zero, which is the workpiece zero point on the X axis. Use one of G54 to G59 to carefully record the mechanical coordinates of the zero position on the X axis of the workpiece, let the machine tool determine the zero position on the X axis of the workpiece, and check the correctness of the data again. The workpiece Y-axis zero setting is the same as the X-axis.

4. Prepare tools

According to the tool data of the programming work guide, replace the tool to be processed, let the tool hit the altimeter on the reference plane, and set the relative coordinate value to zero when the measuring light is on. Move the tool to a safe position, manually move the tool down 50mm, and reset the relative coordinate value to zero. This is the zero point of the Z axis.

The mechanical Z value of this point is recorded in one of G54 to G59. This completes the zeroing of the workpiece X, Y, and Z axes.

Double check the correctness of the data. The touch method on the other side is also to touch one side of the X and Y axes of the workpiece. The point of the X and Y axes relative to the coordinate value of the head radius is the zero point of the X and Y axes, and the mechanical coordinates of the X and Y axes are recorded between G54 and G59. one. Double check the correctness of the data. Check the correctness of the zero point and move the X and Y axes to the workpiece side.

According to the size of the workpiece, check the correctness of the zero point, and then copy the program file to your computer according to the file path of the programming guide.

5. Parameter setting

Spindle speed setting during machining: N=1000×V/(3.14×D)

N: Spindle speed (rpm/min)

V: Cutting speed (m/min)

D: Tool diameter (mm)

Processing feed speed setting: F=N×M×Fn

F: Feed rate (mm/min)

M: Number of blades

Fn: Tool cutting amount (mm/rev)

Setting of cutting amount per edge: Fn=Z×Fz

Z: Number of blades

Fz: Cutting amount of each cutting edge (mm/rev)

6. Preparation for processing

At the beginning of each program, you must double check that the tool you are using was written for the tool specified on the instruction manual. Start cnc machining feed, reduce the feed speed to the lowest, execute single segment, fast positioning, feed, feed must be concentrated, hand should be placed on the stop button, stop immediately if there is a problem, observe the movement direction of the tool to ensure safety The tool is then slowly increased to a suitable feed rate, while the tool and workpiece are applied with coolant or cold air. The cnc rough machining can not be too far from the control panel, if there is an abnormal phenomenon, it should be stopped and checked in time.

Open and pull the table again to make sure the workpiece is not loose. If so, you have to recalibrate and touch that number.

In the process of continuously optimizing CNC machining parameters, the best CNC machining effect is obtained. Because the process is a key process, after the CNC machining of the workpiece is completed, the main dimensions of the drawing should be measured to see if it is consistent with the drawing. If there is any problem, immediately notify the team leader or programmer for inspection. After solving, it must be self-tested and sent to the inspector for special inspection.

Hole processing: In the cnc machining center, the drilling center must first be positioned with a center drill, then drilled with a drill bit smaller than the size of the drawing by 0.5 to 2mm, and finally cnc finishing with a suitable drill bit.

Reaming process: The reaming of the workpiece is also first positioned with a center drill, then drilled with a drill bit smaller than the size of the drawing by 0.5-0.3mm, and finally reamed with a reamer. The reaming process controls the spindle speed of 70-180 rpm.

Boring processing: The workpiece is first drilled with a center drill, then drilled with a drill bit smaller than the size of the drawing 1-2mm, and then processed with a rough boring tool (or milling cutter) to only 0.3mm left on one side and a suitable machining allowance , and finally use the pre-adjusted size of the fine boring tool for fine boring, and the final fine boring allowance cannot be less than 0.1mm. Direct CNC (DNC) operation: Clamp the workpiece, set zero, and set parameters before DNC CNC machining. Open the number of processing programs on the computer to check, then let the computer enter the DNC state, and enter the correct processing program file name. Press the TAPE key and the program start key on the machine, the machine controller will flash the words LSK.

7. Worker self-inspection

Before CNC machining, the processor must read the content of the process card, understand the parts, shapes and drawings of the workpiece, in order to know the size of the process. Before the workpiece is clamped, it is necessary to measure whether the blank size meets the requirements of the drawing. When the installation and programming instructions are consistent with the manual, the workpiece must be carefully checked. After the rough machining is completed, the self-test should be carried out in time to adjust the error of the data in time. The size of the self-test content is mainly the size of the processing site. Such as: whether the workpiece is loose; whether the workpiece is correctly divided; the size of the CNC machining part to the reference edge (reference point) is consistent with the drawing requirements; the position size between the workpieces.

After the completion of the self-inspection, the workers should handle the shape and size of the workpiece after the CNC processing is completed. After the workers complete the self-inspection of the workpiece and confirm the workpiece that conforms to the drawings and process requirements, the inspector will conduct a special inspection.

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