We all know that although the CNC machining center can process many workpieces, it is not omnipotent. There are also restricted areas. Where is the restricted area of ​​the CNC machining center? How did we deal with this situation? Just take out a previous customer case and demonstrate how we solved it.

Because there was a customer who wanted to process a batch of stainless steel workpieces and needed a vertical machining center. This old-fashioned machining center was not good at processing this batch of stainless steel workpieces.

 

Because in the processing of this batch of stainless steel workpieces, there is a problem that the workpiece is a stepped hole, the upper part is Φ26 deep 30MM, the lower part is Φ20 deep 64MM, and the coaxiality is plus or minus 0.08. Generally, we try to do it on a CNC milling machine. At the beginning, we use a center drill to drill, then we use a 20 drill bit, and then we use a milling cutter to mill Φ26 holes. The processing of coaxial old hardware parts is normal. The machining department has such precision, so I will try it out by myself. We drill holes first, and after drilling out, we will slowly grind the holes a bit bigger. This time there is a problem. The hole is not easy to grind. so big.

The main cutting edge of the drill bit is always hit when the amount of reserve is not small in the expanded drilling, and it can’t be ground no matter how much it is sharpened. I continue to sharpen it for a while. I also use the drill bit to drill the margin 0.3~1MM and then use the milling cutter ( Keyway, end mill), but the hole diameter is small.

The following points should be paid attention to the processing method of this kind of processing workpiece:

1. Severe deformation will occur when the vertical machining center is used for stainless steel processing. When processing, it should be divided into rough and fine processing. Do not process both holes to the size at once. Before finishing processing, it is better to loosen the workpiece to release the deformation, and the effect will be better. Then tighten it again. Tight; rough machining uses Φ23 and Φ17 U drills to drill directly to the depth, and then use the composite step boring tool to directly boring the tool size. In this way, the power can be greatly improved, and the accuracy can be easily ensured, so that the coaxiality can definitely be ensured. There is also the question that the coaxiality is not good, not only the technical question, but also the question of the reverse gap of the X-axis and Y-axis of the machine tool, as well as the runout of the spindle, the runout of the tool after installation, whether the fixture is reliable, whether the cutting fluid is poured Abundant, whether the cutting parameters are reasonable, and other details.

 

2. Other suggestions before expanding the drill, use a key milling cutter to correct the straightness of the hole. Simply make sure that the coaxial expansion of the hole is not too small. If this is not possible, it is probably a question of the drill. The drill and milling The theoretical center position of the knife glass processing center is definitely satisfactory, that is to say, when the hole is drilled, it deviates from the theoretical center position, and it is recommended to deal with it from the aspect of drilling;

 

3. Cobalt drills are used for the drill. As for what you said, the key point is that your drill is not well ground. I used to be like you when you drilled the stainless steel eye. Later, I changed the method of grinding the drill and it didn’t break anymore. , And the deeper the stainless steel eye, the harder it is to hit, the bigger the harder it is, the larger the cutting force when the original stainless steel eye is drilled, the drill is easy to twist, but I basically twist the hole on the lathe instead of expanding the stainless steel. hole.