Selection and use of powerful milling cutter toolholder!
June 23, 2022
01. About clamping force
It is difficult to quantitatively answer the question "how much kg · m clamping force is required for Zui to be low (so as not to drop the knife)". Users are easy to fall into the misunderstanding of judging the quality of powerful tool handles based on the nominal holding force in the samples of various brands. In fact, it can not be simply said that a good tool handle has a large holding force.
Take big Dazhao and the powerful milling cutter handle with a clamping force of 300kg · m as an example. For practical use Φ The actual cutting torque of 32 milling cutter is only 60kg · M. even if the safety rate is taken into account, 250kg · m is fully sufficient. However, in addition to the clamping force, the following points are more important!
02. Sufficient shrinkage of inner diameter
In practical application, there are many occasions when the shank diameter of the cutting tool is close to the lower tolerance limit and is used with the reducer sleeve. At this time, no matter how much clamping force the tool handle has, the clamping force can be generated only when the clearance between the inner wall of the tool handle and the reducer sleeve, and the clearance between the reducer sleeve and the tool handle is zero. According to the calculation, if the inner wall of the tool handle does not have a shrinkage of more than 0.1-0.12mm, the clamping force is difficult to reach the nominal value.
03. There is a groove containing oil film on the inner wall
At the processing site, there will be impurities mixed with iron powder and oil dirt, which cannot be completely cleaned no matter how to wipe. If there is no groove in the inner diameter, the generated oil film will easily make the cutting tool slip in the tool handle and reduce the clamping force to less than 1/2.
The size of the groove is also very important, too small can not play the effect, too wide will damage the handle of the cutting tool, resulting in problems in the use process. For example, for a tool handle with a clamping force of 300kg · m, the handle of the tool bears a pressure of 2ton per 1cm2.
04. Inner wall thickness
In the past, the inner wall of the tool handle of the needle roller locking method is relatively thin. Although the clamping force is relatively large, the rigidity of the body is not good, and the tool is easy to fall off. Recently, the tool handle with 10mm thick inner wall has become the mainstream product, which not only ensures the clamping force, but also enhances the rigidity.
05. Runout accuracy
When the cutting parameters are improved, it is easy to pay attention to the clamping force.
Generally, we all know that the most important factor affecting the machining efficiency in cutting conditions is the feed, but we often do not know that the most important factor affecting the feed is the runout accuracy. In addition, it is easy to think of the rigidity of the tool handle when the tool vibrates. However, in fact, it is also one of the important reasons for the vibration of some cutting tools due to the excessive runout accuracy of the tool handle.
06. The central part and the port shall be clamped
The clamping force of the end of the powerful tool handle tends to be weakened, especially when the straight collet is used to clamp the small-diameter cutting tools.
In order to solve this problem, we believe that it is a better scheme to open an appropriate slit at the depth of the inner diameter of the tool handle. The slit can make the body shrink evenly, increase the shrinkage and improve the runout accuracy. In other words, setting a reasonable slit at the inner diameter of the powerful tool handle is indispensable to improve the clamping force, runout accuracy and clamping force at the port.
07. High durability
Needle locking powerful tool handle according to Article 3, 60Ton pressure will be generated after tightening the nut. Long term use will cause wear on the surface of the needle. At this time, the service life of the tool handle should be considered.
The service life of powerful milling shanks in the market is different, and the service life of different brands varies from 1 to 5 times, which requires users to have sufficient discrimination.
The tool handle with deteriorated accuracy will have a serious impact on the service life of machine tools and cutting tools. Some impacts are not easy to detect but are very serious. Regular inspection and timely replacement are required.
08. Marking on the handle of the cutting tool
In order to verify the impact of the tool shank scar on the clamping force, we artificially added three scratches with a depth of about 0.04mm to the shank diameter of the milling cutter. The final test results showed that the clamping force would be reduced to 1/2~1/5 of the nominal value.
In case of tool drop, the first thing we think about is the clamping force of the tool handle. In fact, it is very important to confirm whether there are scratches on the milling tool holder.
