The tool will produce a component force (Fp) in the radial direction when processing the workpiece, as shown in the figure below:

 

 

 

 

When the force is applied, if the rigidity of the tool is insufficient, the tool body will be deformed, and there will be a deviation in the direction of the force and a displacement.

 

The tool has a displacement, so the depth of the knife is reduced, the force is also reduced, and the displacement generated is also reduced.

 

The resulting displacement becomes smaller, and the tool moves in the opposite direction of the force, so that the depth of the cutting tool becomes larger and the cutting becomes larger.

 

This is like comparing the tool to a slender wooden stick. One end is fixed and the other end is stressed. Then the end away from the unfixed end will deflect and rebound.

 

In this way, during the machining process, the constantly changing cutting force acts on the tool and the workpiece, resulting in vibration.

 

 

 

 

 

 

 

Then we can see that there are two directly related factors that produce vibration:

 

One, the strength of the blade itself.

 

Second, the size of the cutting force.

 

Of course, it is also related to other factors, such as the strength of the workpiece (the workpiece will also be displaced), machine tools, fixtures, processing parameters, etc. Junge will not analyze it.

 

 

 

One, the strength of the knife body itself

 

The strength of the knife body itself, this is easy to understand, the thicker and shorter, the greater the strength, so if you want to solve the vibration problem in this direction, then make the knife body shorter and thicker, and it will definitely solve the problem. . If the processing length is required, the following issues should also be paid attention to.

 

1. The extension length of the steel arbor is controlled within 3 times the diameter.

2. The extended length of the heavy metal cutter bar is controlled within 6 times the diameter.

3. If you want to use as long as possible, use the shock-absorbing tool bar.

 

Second, the size of the cutting force

 

Cutting force, this is better understood, the smaller the cutting force, the smaller the vibration. From the tool point of view, you can choose the right tool from the following two aspects, and the effect will be immediate.

 

1. Tools with large rake angle and small cutting edge width.

 

Regarding the width of the cutting edge of the tool, many friends said that they don’t know, and the specific concept will not be explained. A picture is worth a thousand words, as shown in the following figure:

 

 

 

 

 

 

The rake angles of the two types of blades above are 20 degrees and 24 degrees, and the cutting edge width is 0.27 and 0.12 respectively.

 

That is to say, the larger the rake angle, the smaller the edge width means the sharper the tool, and the smaller the cutting force during the cutting process.

 

In addition, the cutting edge width of the tool is very important. It directly determines the size of the feed F during programming. The selection of cutting parameters will be shared later.

 

 

 

2. Tool entering angle

 

In the process of cutting a part, the tool receives two forces, axial and radial cutting forces.

 

For example, as shown in the figure below:

 

 

 

The picture above shows a tool with an entering angle of 45°. The length of the red arrow indicates the magnitude of the force in this direction, that is, the radial force is greater than the axial force.

 

 

 

 

 

 

 

The picture above shows a tool with an entering angle of 95°. The length of the red arrow indicates the magnitude of the force in this direction, that is, the radial force is less than the axial force.

 

In other words, the size of the entering angle of the tool directly determines the size of the radial cutting force. The larger the entering angle of the tool, the smaller the cutting force in the radial direction, and the smaller the entering angle, the greater the cutting force in the radial direction.

 

As shown below:

 

 

 

 

 

 

 

 

The above three common tool entering angles are: 90°, 75°, 45°. The smaller the entering angle, the greater the radial force and the greater the tendency of tool vibration.

 

Well, today’s dry goods will be shared here. If you take a general look and think that you also know this knowledge, or you understand it by yourself, and you don’t think deeply, then it will be difficult for you to learn something and make achievements.

 

Please remember that knowing does not mean that you will!

 

Brother Jun, the dry goods I shared, you look at it in general, it seems that there is nothing tall, but if you think hard and draw inferences, everything will be completely different.

 

for example:

 

When machining deep holes, have you ever encountered unstable hole sizes?

 

what reason?

 

If you analyze it from the perspective of the tool, you should think carefully about the principle of vibration at the beginning of the article.

 

When the force is applied, if the rigidity of the tool is insufficient, the tool body will be deformed, and there will be a deviation in the direction of the force and a displacement. This is a good explanation why the size is unstable.

 

If you think about it further, when the tool is cutting the part, the part will also be subjected to force. If the rigidity of the part is insufficient, the part will also have displacement and deflection.

 

If the tool is sharp, because it is far away from the clamping end, the part deflection will be large when the cutting force is applied, then more cutting will occur. If the hole is machined, the hole size will be larger.... This is what the master commonly calls the processed parts belt.

 

How to solve it, if the rigidity of the part itself is insufficient, it is difficult to solve the problem in clamping, then from the tool, for example, choose a tool with a larger entering angle to reduce the force in the radial direction of the part, thereby reducing the deflection of the part due to insufficient rigidity ,shock…….

 

Well, people in this era are very impetuous. Many people have a general look at the dry goods shared by Brother Jun, and then wait for the next new article. In this way, no matter how much they watched, they didn't really grow up, and they seemed to be very hardworking and lazy. why?

 

1. No deep thinking

 

Those in our business are more professional. The important thing is not how much you have seen and understood, but how much you have thought deeply, how much you understand, and how much you use.

 

2. No systematics

 

Knowledge can be said to be one link after another, all links are connected. Monkeys help corn-style learning. It takes a lot of effort to get things done, and it pays a lot. In the end, it has little effect, which is very worrying.

 

So how to learn systematically and think deeply?

 

Take UG software programming for example:

 

Although there are thousands of knowledge points in UG's parameter commands, this is a fact, but Brother Jun, I have constructed my own theoretical system to simplify the complex, leave the complex to myself, and simply present it to others. For details of this theoretical system, please refer to the article "Building Four UG Systems, Let You Have Fun with UG Software Programming".

 

Another example is macro programming. Many people think that macro programming is very mysterious and difficult to learn. At the same time, in today's popular software programming, it seems unnecessary to learn. In fact, when you think deeply, you will find that all fields are actually Are the same.

 

For example, [Plane Milling] in UG software programming, I have summarized two characteristics:

 

1. [Plane milling] does not define the processing geometry by three-dimensional entities, but uses edges or boundary lines created by curves to determine the processing area.

 

2. [Plane milling] The tool path is from the first layer to the last layer. The tool path of each layer is strictly the same as the previous or next tool path except for the depth.

 

Thanks to the second feature of [UG plane milling], I made a [macro program] hierarchical programming framework for Brother Jun, a ready-made programming framework, and apply the framework around the ideas taught by Jun Brother. Soon Write your own macro program!

 

When you have mastered [macro program] hierarchical programming, you will suddenly realize that when you learn UG programming, this is the characteristic of UG surface milling! When you learn UG, come to play macro programming and think deeply, and you will discover many similarities.