In the process of CNC machining, it is very common to process cylindrical grooves and end grooves. In the process of machining external circular grooves and end grooves, we should analyze and understand the cutting tools and grinding, grooving processing technology and grooving quality analysis, so as to ensure that the quality and accuracy of processed products meet the requirements.
1、 Grinding of cutting tools for grooving
First, rough grind the front, the back of the pair on both sides and the back of the main to make the cutter head basically shaped; Then finish grinding the front and front corners; Then finish grinding the back of the pair and the main rear corner; Then finish grinding the back of the vice and the back of the main, and finally polish the knife tip.
When grinding the auxiliary rear corners on both sides of the groove, take the bottom surface of the turning tool as the benchmark and check with a 90 degree angle ruler.
The main blade of the slotting knife and the auxiliary blades on both sides should be balanced and straight. When sharpening the auxiliary deflection angle of the grooving cutter, it is necessary to prevent the occurrence of too large auxiliary deflection angle, uneven auxiliary blade, too much grinding on one side of the turning tool, etc.
2、 Grooving process
Whether the slotting knife is clamped correctly has a direct impact on the quality of the slotting. Generally, it is required that the tip of the grooving tool is equal to the axis of the workpiece, and the cutter head is perpendicular to the axis of the workpiece.
When turning rectangular grooves with low precision and narrow width, a groove cutter with a knife width equal to the groove width can be used, and the straight in method is used for one-time feeding and turning. Grooves with high accuracy requirements are generally formed by secondary feeding, that is, when the groove is fed for the first time, fine machining allowance is left on both sides of the groove wall, and the same width knife is used for finishing during the second feeding.
The wide groove can be cut by multiple straight cutting, and the finishing allowance shall be left on the groove wall and bottom, and the final cutting shall be finished to the size. Smaller trapezoidal grooves are usually turned with a forming knife. Larger trapezoidal grooves are usually turned into straight grooves first, and then completed by trapezoidal knife straight cutting method or left-right cutting method.
3、 Grooving quality analysis
Common quality problems and finishing methods during grooving are as follows.
1. The reason why the groove bottom has vibration marks is that the clamping rigidity of the grooving knife is insufficient. It is necessary to change the knife with good rigidity or reduce the extension length to increase the clamping rigidity.
2. The roughness of the groove bottom is out of tolerance, and it is necessary to regrind the tool or replace the blade.
3. If the diameter of the groove bottom is incorrect, adjust the tool again or compensate by modifying the wear value.
4. The groove width dimension is incorrect, and the tool width parameter or program needs to be modified.
4、 Precautions for grooving processing
1. The main cutting edge of the grooving cutter should be straight and the angle should be appropriate.
2. When installing the cutting tool, the cutting edge should be equal to the center of the workpiece, and the main cutting edge should be parallel to the axis line.
3. The rotation speed and feed rate should be reasonably selected.
4. Use cutting fluid correctly.
5. The back of one side of the end grooving knife should be ground into an arc shape to prevent friction with the groove wall.
6. The groove side and bottom shall be straight and clear.
7. It is easy to produce vibration when turning the end groove. If necessary, the reverse cutting method can be used for turning.
