The Common Trouble and Its Solution in Machining Thread of CNC Lathe（2）
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Update time : 2017-01-06 11:26:50
2. Random deduction
2.1 Symptoms
When the screw rotates, the workpiece is not turned to the integer result.
2.2 The main reasons
Machine spindle encoder synchronization belt wear, spindle synchronization can not detect the true speed; programming the input host is not correct; X-axis or Y-axis screw wear.
2.3 Solutions
(1) Synchronous belt wear of the spindle encoder: As the NC lathe turning thread, the spindle and tool movement is the host machine information processing center issued instructions to control, turning thread, the spindle speed constant invariant, X or The Y-axis can adjust the movement speed according to the workpiece lead size and the spindle speed, so the spindle must detect the spindle synchronous true speed in order to issue the correct command to control the X or Y axis to move correctly. If the system can not detect the true speed of the spindle, the actual turning will issue a different command to the X or Y, then the spindle to a turn, the tool moves the distance is not a lead, the second turning thread will Random deduction. In this case, we only repair the machine, replace the spindle timing belt.
(2) the preparation of the input program is not correct: turning thread in order to prevent chaos deduction, we must ensure that the knife after turning the track with the previous tool to turn the track coincidence, in the general car we use inverted car law to prevent chaos deduction. In the CNC lathe, we use the program to prevent chaos deduction, that is, in the preparation of processing procedures, we use the program control screwdriver before turning the knife after the knife, so that the starting position after the knife with the beginning position of the previous knife coincidence (equivalent to General car turning thread, the thread knife back to the knife before the car out of the spiral groove), so that the car will not be out of the screw thread. Sometimes, due to the program input of the lead is not correct (the latter part of the program lead and a program lead is not consistent with the previous paragraph), turning the phenomenon of chaos deduction will appear.
(3) X-axis or Y-axis serious wear and tear: the maintenance of machine tools, replacement of X-axis or Z-axis screw.
3 Pitch is not correct
3.1 The main reasons
Spindle encoder sent back to the machine tool system data inaccurate; X axis or Y axis screw and spindle movement is too large; preparation and input of the program is not correct.
3.2 Solutions
(1) spindle encoder transmission data is not accurate: maintenance of machine tools, replacement of spindle encoder or synchronous conveyor belt;
(2) X-axis or Y-axis screw and spindle movement is too large: adjust the axial axial movement, X-axis or Y-axis screw gap can be compensated with automatic compensation system gap;
(3) to view the program, be sure to make the program instructions and drawings consistent with the requirements.
4 tooth type is not correct
4.1 The main reasons
Cutter blade grinding is not correct; turning tool is not installed correctly; turning tool wear.
4.2 Workaround
(1) Tool tip grinding is not correct: the correct grinding and measuring the angle of the tool tip, the tooth-type angle for a higher degree of precision thread turning, you can use standard mechanical clamping screw thread turning, or thread Knife grinding machine grinding.
(2) tool is not installed correctly: the knife with a knife when the knife, or by using a dial indicator to align the thread arbor to install a screwdriver.
(3) turning tool wear: According to the actual situation of turning, the rational choice of cutting consumption, timely grinding tool.
5 thread surface roughness large fault analysis
5.1 The main reasons
Cutting edge is too large; high-speed cutting thread, the cutting thickness is too small or the chip to the direction of the discharge discharge, the tooth has been processed tooth surface; the workpiece surface of the workpiece is not enough; Rigidity is poor, and the cutting amount is too large; turning tool surface roughness difference.
5.2 Workaround
(1) cutting with high-speed steel cutting tool should reduce the cutting speed, and the correct choice of cutting fluid;
(2) to increase the shank section, and reduce the handle extension length;
(3) reducing the radial rake angle;
(4) high-speed steel cutting thread, the last knife chip thickness is generally greater than 0.1mm, and the chip along the vertical axis of discharge;
(5) choose a reasonable amount of cutting;
(6) The surface roughness of the cutting edge should be 2-3 grades smaller than the surface roughness.
In short, turning thread generated when the failure of a variety of forms, both the reasons for the machine, there are tools, operators and other reasons, to troubleshoot specific circumstances specific analysis, through a variety of testing and diagnostic tools to identify specific Influence factors, to take effective solutions.
2.1 Symptoms
When the screw rotates, the workpiece is not turned to the integer result.
2.2 The main reasons
Machine spindle encoder synchronization belt wear, spindle synchronization can not detect the true speed; programming the input host is not correct; X-axis or Y-axis screw wear.
2.3 Solutions
(1) Synchronous belt wear of the spindle encoder: As the NC lathe turning thread, the spindle and tool movement is the host machine information processing center issued instructions to control, turning thread, the spindle speed constant invariant, X or The Y-axis can adjust the movement speed according to the workpiece lead size and the spindle speed, so the spindle must detect the spindle synchronous true speed in order to issue the correct command to control the X or Y axis to move correctly. If the system can not detect the true speed of the spindle, the actual turning will issue a different command to the X or Y, then the spindle to a turn, the tool moves the distance is not a lead, the second turning thread will Random deduction. In this case, we only repair the machine, replace the spindle timing belt.
(2) the preparation of the input program is not correct: turning thread in order to prevent chaos deduction, we must ensure that the knife after turning the track with the previous tool to turn the track coincidence, in the general car we use inverted car law to prevent chaos deduction. In the CNC lathe, we use the program to prevent chaos deduction, that is, in the preparation of processing procedures, we use the program control screwdriver before turning the knife after the knife, so that the starting position after the knife with the beginning position of the previous knife coincidence (equivalent to General car turning thread, the thread knife back to the knife before the car out of the spiral groove), so that the car will not be out of the screw thread. Sometimes, due to the program input of the lead is not correct (the latter part of the program lead and a program lead is not consistent with the previous paragraph), turning the phenomenon of chaos deduction will appear.
(3) X-axis or Y-axis serious wear and tear: the maintenance of machine tools, replacement of X-axis or Z-axis screw.
3 Pitch is not correct
3.1 The main reasons
Spindle encoder sent back to the machine tool system data inaccurate; X axis or Y axis screw and spindle movement is too large; preparation and input of the program is not correct.
3.2 Solutions
(1) spindle encoder transmission data is not accurate: maintenance of machine tools, replacement of spindle encoder or synchronous conveyor belt;
(2) X-axis or Y-axis screw and spindle movement is too large: adjust the axial axial movement, X-axis or Y-axis screw gap can be compensated with automatic compensation system gap;
(3) to view the program, be sure to make the program instructions and drawings consistent with the requirements.
4 tooth type is not correct
4.1 The main reasons
Cutter blade grinding is not correct; turning tool is not installed correctly; turning tool wear.
4.2 Workaround
(1) Tool tip grinding is not correct: the correct grinding and measuring the angle of the tool tip, the tooth-type angle for a higher degree of precision thread turning, you can use standard mechanical clamping screw thread turning, or thread Knife grinding machine grinding.
(2) tool is not installed correctly: the knife with a knife when the knife, or by using a dial indicator to align the thread arbor to install a screwdriver.
(3) turning tool wear: According to the actual situation of turning, the rational choice of cutting consumption, timely grinding tool.
5 thread surface roughness large fault analysis
5.1 The main reasons
Cutting edge is too large; high-speed cutting thread, the cutting thickness is too small or the chip to the direction of the discharge discharge, the tooth has been processed tooth surface; the workpiece surface of the workpiece is not enough; Rigidity is poor, and the cutting amount is too large; turning tool surface roughness difference.
5.2 Workaround
(1) cutting with high-speed steel cutting tool should reduce the cutting speed, and the correct choice of cutting fluid;
(2) to increase the shank section, and reduce the handle extension length;
(3) reducing the radial rake angle;
(4) high-speed steel cutting thread, the last knife chip thickness is generally greater than 0.1mm, and the chip along the vertical axis of discharge;
(5) choose a reasonable amount of cutting;
(6) The surface roughness of the cutting edge should be 2-3 grades smaller than the surface roughness.
In short, turning thread generated when the failure of a variety of forms, both the reasons for the machine, there are tools, operators and other reasons, to troubleshoot specific circumstances specific analysis, through a variety of testing and diagnostic tools to identify specific Influence factors, to take effective solutions.