01 startup preparation
After the machine tool is started or reset according to the emergency stop, first return to the reference zero position of the machine tool (i.e. return to zero), so that the machine tool has a reference position for its subsequent operation.
02 clamping workpiece
Before clamping the workpiece, clean all surfaces without oil, scrap iron and dust, and remove the burrs on the workpiece surface with a file (or oilstone).
The surface of the high-speed rail used for clamping must be grinded by the grinder to make it smooth and flat. The code iron and nut must be firm and can reliably clamp the workpiece. For some small workpieces that are difficult to clamp, they can be directly clamped on the tiger; The workbench of the machine tool shall be clean and free of iron filings, dust and oil stain; The sizing block is generally placed at the four corners of the workpiece. For the workpiece with too large span, it is necessary to add equal height sizing block in the middle.
Check whether the length, width and height of the workpiece are qualified with a ruler according to the dimensions of the drawing.
When clamping the workpiece, according to the clamping placement mode of the programming operation instruction, it is necessary to consider avoiding the machined parts and the situation that the cutter head may touch the fixture during machining.
After the workpiece is placed on the sizing block, pull the table on the workpiece datum plane according to the requirements of the drawing. For the workpiece that has been ground on six sides, check whether its perpendicularity is qualified.
After the workpiece is pulled, the nut must be tightened to prevent the workpiece from shifting during processing due to unstable clamping; Pull the meter again to ensure that the error does not exceed the error after clamping.
03 number of workpiece hits
For the clamped workpiece, the touch number head can be used to determine the processing reference zero position. The touch number head can be photoelectric and mechanical. There are two kinds of methods: middle collision number and unilateral collision number. The steps of dividing middle collision number are as follows:
Photoelectric static, mechanical speed 450 ~ 600rpm. Manually move the x-axis of the worktable to make the touch head touch one side of the workpiece. When the touch head just touches the workpiece and the red light is on, set the relative coordinate value of this point to zero; Then manually move the x-axis of the workbench to make the counting head touch the other side of the workpiece. When the counting head just touches the workpiece, record the relative coordinates at this time.
Check whether the length of the workpiece meets the requirements of the drawing by subtracting the diameter of the collision head (i.e. the length of the workpiece) from its relative value.
Divide the number of relative coordinates by 2, and the obtained value is the middle value of the x-axis of the workpiece. Then move the workbench to the middle value of the x-axis, and set the relative coordinate value of the x-axis at this point to zero, which is the zero position on the x-axis of the workpiece.
Carefully record the mechanical coordinate value of the zero position on the x-axis of the workpiece in one of g54 ~ G59, and let the machine tool determine the zero position on the x-axis of the workpiece. Carefully check the correctness of the data again. The procedure for setting the zero position of workpiece Y axis is the same as that of X axis.
04 prepare all tools
According to the tool data in the programming operation instruction, replace the tool to be processed, let the tool touch the height gauge placed on the datum plane, and set the relative coordinate value of this point to zero when the red light of the gauge is on.
Move the tool to a safe place, manually move the tool down 50mm, and set the relative coordinate value of this point to zero, which is the zero position of Z axis.
Record the mechanical coordinate Z value of this point in one of g54 ~ G59. This completes the zero setting of X, y and Z axes of the workpiece. Carefully check the correctness of the data again.
The single side touch count also touches one side of the X and Y axes of the workpiece according to the above method. Offset the relative coordinate values of the X and Y axes at this point, and the radius of the touch count head is the zero position of the X and Y axes. Finally, record the mechanical coordinates of the X and Y axes at one of g54 ~ G59. Carefully check the correctness of the data again.
Check the correctness of the zero point, move the X and Y axes to the side overhang of the workpiece, and visually check the correctness of the zero point according to the size of the workpiece.
Copy the program file to the computer according to the file path of the programming operation instruction.
05 setting of machining parameters
Setting of spindle speed during machining:
N=1000 × V/（3.14 × D）
N: Spindle speed (RPM / min)
5: Cutting speed (M / min)
D: Tool diameter (mm)
Feed speed setting for machining: F = n × M × Fn
F: Feed speed (mm / min)
M: Number of cutting edges
FN: cutting amount of the tool (mm / revolution)
Cutting amount setting of each edge: FN = Z × Fz
Z: Number of cutting edges of the tool
FZ: cutting amount of each edge of the tool (mm / revolution)
06 startup processing
At the beginning of each program, carefully check whether the tool used is the tool specified in the programming instruction. At the beginning of machining, the feed speed shall be adjusted to the minimum and executed in a single section. Concentrate on rapid positioning, tool dropping and feeding. Put your hand on the stop key. Stop immediately if there is a problem. Pay attention to observe the moving direction of the tool to ensure safe feeding, and then slowly increase the feed speed to an appropriate level. At the same time, add coolant or cold air to the tool and workpiece.
During rough machining, it shall not be too far away from the control panel. In case of any abnormality, stop the machine for inspection in time.
Pull the gauge again after roughing to ensure that the workpiece is not loose. If any, the and collision number must be corrected again.
Continuously optimize the processing parameters in the processing process to achieve the best processing effect.
Since this process is a key process, after the workpiece is processed, measure whether the main dimension values are consistent with the drawing requirements. If there is any problem, immediately notify the team leader or programmer on duty to check and solve it. After passing the self inspection, it can be removed and must be sent to the inspector for special inspection.
Hole processing: before drilling on the machining center, be sure to use the center drill for positioning, then drill with a drill bit 0.5 ~ 2mm smaller than the size of the drawing, and finally finish machining with a suitable drill bit.
Reaming processing: for the reaming processing of the workpiece, the center drill shall be used for positioning first, then the drill bit 0.5 ~ 0.3mm smaller than the size of the drawing shall be used for drilling, and finally the reamer shall be used for reaming. During reaming processing, pay attention to control the spindle speed within 70 ~ 180rpm / min.
Boring processing: for the boring processing of the workpiece, the center drill shall be used for positioning, and then the drill bit 1 ~ 2mm smaller than the drawing size shall be used for drilling, and then the rough boring cutter (or milling cutter) shall be used to process to only about 0.3mm machining allowance on one side. Finally, the fine boring cutter with pre adjusted size shall be used for fine boring, and the last fine boring allowance shall not be less than 0.1mm.
Direct numerical control (DNC) operation: before DNC NC machining, the workpiece shall be clamped, the zero position shall be set and the parameters shall be set. Open the machining program to be transmitted in the computer for inspection, then let the computer enter the DNC state and enter the file name of the correct machining program. Press tape key and program start key on the machining machine tool, and the word LSK flashes on the machine tool controller. Press enter on the computer to carry out DNC data transmission processing.
07 contents and scope of self inspection
Before processing, the processor must clearly see the contents of the process card, clearly know the parts, shapes and dimensions of the workpiece to be processed, and know the processing contents of the next process.
Before clamping the workpiece, measure whether the blank size meets the drawing requirements. When clamping the workpiece, carefully check whether its placement is consistent with the programming operation instruction.
Self inspection shall be carried out in time after rough machining, so as to adjust the error data in time. The self inspection content mainly includes the position and size of the processing part. For example, whether the workpiece is loose; Whether the workpiece is correctly divided; Whether the dimension from the processing part to the datum edge (datum point) meets the drawing requirements; Position and size of machining parts. After checking the position and size, measure the rough machined shape ruler (except circular arc).
Finish machining is carried out only after rough machining and self inspection. After finishing, workers shall conduct self inspection on the shape and size of the processing parts: detect the basic length and width of the processing parts on the vertical surface; Measure the base point dimension marked on the drawing for the machining part of the inclined plane.
After the worker completes the self inspection of the workpiece and confirms that it meets the drawing and process requirements, the workpiece can be removed and sent to the inspector for special inspection.
Post time: Nov-17-2021