Stainless steel reaming often encounters: the surface of the hole is easy to draw grooves, the roughness is poor, the aperture is out of tolerance, the bell mouth is flared, and the reamer is easy to wear. Different types of stainless steel have different machinability, and the problems in reaming are different. For example, when austenitic stainless steel such as 1Cr18Ni9Ti and concentrated nitric acid resistant stainless steel are reamed, the problem is mainly reamer wear; and for 2Cr13, etc. When the martensite stainless steel is reamed, it is not easy to ensure the roughness and dimensional accuracy of the reaming. To avoid these problems, you should be aware of the following:
1. Reasonable selection of reamer and reaming is the key to ensuring smooth reaming.
2, improve the quality of the pre-processing process, prevent the pre-machined hole from appearing grooves, ellipse, polygon, taper or bell mouth, waist drum shape, axis bending, skew and so on.
3. Keep the material hardness of the workpiece moderate, especially for 2Cr13 martensitic stainless steel. The hardness after quenching and tempering is below HRC28.
4. Correctly install the reamer and the workpiece. The reamer must be installed correctly. The axis of the reamer should be consistent with the axis of the pre-machined hole of the workpiece to ensure uniform cutting of each tooth.
5. Selecting the right cutting fluid can solve the problem of stainless steel chip sticking and smooth chip removal, thus reducing the surface roughness of the hole and improving the durability of the tool. Generally, it is preferred to use a sulfurized oil. If 10% to 20% of CCl4 is added to the sulfurized oil or 20% to 30% of CCl4 is added to the lard, the surface roughness is remarkably improved. Since CCl4 is harmful to the human body, it is preferred to use a mixture of 85% to 90% of sulfurized oil and 10% to 15% of kerosene. When the diameter of the reamer is large, internal cooling can be used.
6. Paying careful attention to the process of reaming and strictly checking the amount of tooth movement is the key to obtaining uniform reaming. During the reaming process, pay attention to the shape of the chips. Due to the small amount of reaming, the chips are in the form of a foil or a short spiral. If the size of the chips is different, some are broken and some are small, which means that the reaming is uneven. If the chips are in the form of a spring, the reaming allowance is too large. If the chips are needle-like or fragmented, the reamer has been blunt. Also to prevent chip clogging, should be diligent in observing the presence or absence of sticky teeth to avoid excessive hole diameter. When reaming with a carbide reamer, hole shrinkage occurs. To prevent the hole from being pulled when retracting, an increase in the lead angle can be used to improve the situation.
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