chengcg – Page 83 – CNC Machining & Turning, Milling, Metal parts

Causes of die punch fracture

In the process of our processing, it is a normal phenomenon to encounter problems, because during the operation of the equipment, there will be wear between the parts. If there is wear, the fault will occur naturally. If the fault occurs more, it will certainly affect the service life of the equipment. So if we want to extend the service life, we must do well in the maintenance The problem must be solved in time, so let’s understand what causes the die punch fracture?

In the blanking process, the punch is subjected to unbalanced lateral pushing force, which makes the punch bend or even break. This kind of force mainly includes the following aspects:

① When rubber is used as elastic unloading part, rubber compresses to produce lateral expansion and extrudes punch to one side due to improper assembly.

② The imbalance of spring force in the unloading device makes the unloading plate incline, which makes the punch bend and break when it is pushed by transverse force.

③ The position of the big punch and the small punch are close. In the blanking process, the material around the big hole deforms, and the small punch may break.

If the ratio between the diameter of punch section and the length of its working part is improper, the punch may be broken.
When a small punch is used to punch thick and hard materials, the punch is easy to break, and the diameter of common punch should be larger than the material thickness of metal stamping parts. Otherwise, punch sheath structure should be adopted.
Die fracture is also often caused by incorrect design and manufacturing, small fillet radius at corner of step punch, rough machining, no edge mark and grinding crack, decarburization layer caused by forging is not completely removed by machining, carbide segregation is not improved during forging of high alloy tool steel, improper heat treatment process and so on. Especially for cold extrusion punch.

Prevent CNC parts from machining deformation

In the production process, we always encounter some new problems, of course, problems will directly affect our work efficiency, in this process, there will be many uncontrollable factors, resulting in the quality of products can not be guaranteed, not only external factors are very important, but also the original mold equipment has a great impact. Parts will also deform during processing. If this happens, we need to stop working immediately and carry out correct treatment. What should we do to prevent this situation in the later stage?

1、 In order to reduce the influence of cutting force and cutting heat, the deformation caused by rough machining can be corrected in finish machining.

2、 To reduce the influence of clamping force, the following measures should be taken to reduce the influence of clamping force:

When using radial clamping, the clamping force should not be concentrated on a certain radial section of the workpiece, and the operator should make it distributed over a large area to reduce the clamping force on the unit area of the workpiece.
The position of clamping force should be selected at the part with strong rigidity to improve the deformation of thin-walled parts under the action of clamping force.
The direction of clamping force is changed from radial clamping to axial clamping.
It is suggested that before purchasing computer gong equipment, the manufacturer must have a detailed understanding and investigation. In order to reduce the clamping deformation, special claws are used to clamp the workpiece, and the convex edge is cut off at the end of processing.

Route determination of CNC specular

As we all know, CNC high gloss machine is a kind of automatic machine tool controlled by program. The control system can process the program with control code or other symbol instruction rules logically, and decode it from beginning to end by computer, so that CNC lathe can act and process parts, and the blank material can be processed into semi-shaped articles and molded parts by cutting tools all the time. So how to determine the route of CNC highlight machine? Let’s take a simple look:

The feed machining route of CNC high gloss machine refers to the path from the start of tool setting point (or CNC lathe’s unchanged origin) to returning to the point and ending the machining program, including the path of cutting and the non cutting path of tool cutting in and cutting out. The feed path of finish machining is basically carried out in sequence along the appearance of the parts. Therefore, the focus of confirming the feed path is to confirm the feed path of rough machining and empty stroke.

The above is the principle to determine the machining route of CNC high gloss machine. Due to its good rigidity, high manufacturing accuracy, accurate tool setting, and convenient dimensional compensation, it can process parts with high dimensional accuracy and complex contour shape.

CNC processing and installation environment requirements

We all know that many mechanical equipment in the installation of the environment are certain requirements, because the installation directly affects our later use, one step of the installation is not correct, or in other words, there are some environmental impact during the installation process, so the later work is also likely to be affected, so let’s learn about CNC plus What are the environmental requirements for installation?

Location requirements

It should be far away from the vibration source and direct sunlight. If there is a seismic source nearby, an earthquake proof trench should be set up.

Temperature and humidity

The optimal processing temperature of CNC machining center is below 30 ℃. If the ambient temperature and humidity are too high, the service life of the control system components may be reduced. If the ambient humidity is too high, it may lead to the short circuit and fault of the integrated circuit board.

Voltage and current control

There are many processing equipment in the workshop, which will cause excessive fluctuation of the power grid. We need to control the voltage and current within the allowable range of the machining center and keep it stable, otherwise, the work of the system may be affected

Control CNC machining center cutting spring cutter

In the process of processing, we will certainly encounter some unexpected accidents. If there are some accidents in the process of processing, there must be a certain degree of danger, so we must do some preventive measures to avoid the real failure and injury to people. Then we will learn how to control the spring knife in the cutting process of CNC machining center.

In the process of machining, the length of the tool should be shortened as far as possible to reduce the risk of tool bounce. The relationship between tool deformation and tool diameter is the fourth power. For the same length of tool, when the tool diameter is reduced by one time, the deformation will increase by 4 times. In the process of processing, if possible, select large-diameter cutting tools or use reinforced cutting tools to reduce the risk of knife snapping. (as shown in the figure on the right below: a uses the heat cable and taper neck knife, and B uses the tool with strong handle for processing)

The deformation of the tool is in direct proportion to the force exerted on the tool in the process of machining. Reducing the force on the tool can reduce the chance of snapping the tool. The following methods can be used to reduce the force on the tool in machining.

Reduced force analysis:

Cutting is a process of shear deformation. Each material has its own strength (σ). In order to separate the materials, the strength from outside must be greater than that of the material itself.

The punch fell off during the stamping process

No matter what kind of work you are doing, it is common to have problems in the process of work. If you encounter problems, you must solve them in time to avoid causing bigger problems later. However, there is a problem that many users easily ignore when dealing with a problem, that is, they will not find the reason, just solve the problem directly. Before solving the problem, we must find out the reason first, so as to eliminate the root. Then we will understand what causes the punch to fall off in the stamping process?

For the fixed structure of punch pressed in by interference fit, the punch is easy to loose and fall off because it fails to meet the required interference during manufacturing and is remedied by “twist extrusion and chiseling”.
If the punch is not stepped or fixed with fasteners, the unloading force will increase and the punch will be pulled out when the thick, hard or viscous material is punched and the clearance between the discharge plate hole and the punch is too small.
The rigidity of punch or die base is poor, and elastic deformation occurs in the process of blanking, which makes the punch collide with the discharge plate or gets stuck with the female die, which increases the unloading force and makes the punch pull out easily.
If the gap between punch and die is too small and the working surface is rough or the gap is inclined to one side, the discharge force can be increased and the punch can be pulled out.
The die with low melting point and die is easy to pull out when assembling.

Reasons for uneven shape of stamping and drawing parts

No matter what the problem is, if we want to solve the problem, the first thing is to find out the cause of the problem, so that we can solve the problem according to the order. If we only solve the surface problem, then we believe that it will recur in a short time. Then we will understand what causes the uneven shape of stamping and drawing parts?

There is no air hole on the punch.

In the stamping process, the air in the workpiece is compressed by the punch and can not be discharged, which makes the shape of the drawing part uneven. This reason is often ignored by many people. The solution is to add air holes on the punch.

The blank is not smooth.

The surface of the blank is not smooth, which leads to the surface unevenness of the drawing part. The solution is to replace the material with good surface quality.

The material has large rebound.

The springback of material is large, resulting in uneven shape of drawing parts. The solution is to increase annealing or shaping process.

The gap between punch and die is too large.

If the gap is too large, the working surface of the die will lose the straightening effect on the workpiece wall, and the workpiece shape will be uneven. Therefore, the die gap should be repaired or replaced with new parts.

The negative deviation of material thickness is too large.

If the thickness of the material is too small, the gap between the dies will be relatively large, resulting in uneven shape. It is necessary to change the material with proper thickness.

General knowledge of gantry milling

When processing, we will encounter a lot of fault problems, which are caused by some problems between parts or some operation problems. Before processing, we need to understand the common sense of processing technology. Then we will learn about the common sense of the Dragon Gate milling process

What is gantry milling processing: gantry milling processing, full name: gantry milling machine processing.
Classification of gantry milling machining center: gantry milling machining center generally has portal frame and horizontal long bed.
Characteristics of gantry milling: it can use multiple milling cutters to process the surface at the same time, and the machining accuracy and production efficiency are relatively high
Application scope of gantry milling: gantry milling is suitable for processing plane and inclined plane of large workpiece in batch and mass production.
The difference between gantry milling and CNC gantry milling: CNC gantry milling machine can also process space curved surface and some special parts.
The difference between the gantry milling machine and the planer: when the gantry milling machine is processing, the shape of the gantry milling machine is similar to that of the planer planer. The difference lies in that the cross beam and column of the gantry milling machine are not planer tool holders, but milling tool holders with spindle box. And the reciprocating motion of the longitudinal table of the gantry milling machine is not the main motion, but the feed motion, and the rotary motion of the milling cutter is The main movement.

There are also some variants of the gantry milling machine to adapt to different processing objects. The main parameter of the gantry milling machine is the width of the working table, and there are also the gantry width as the parameter. Let’s talk about it today. If you want to know more, please visit Dongguan machining website

Machining concept

Machining process is the process of manufacturing workpieces or parts. The process of changing the shape, size and surface quality of blank directly by mechanical processing method is called machining process. For example, the processing process of an ordinary part is rough machining – finishing – assembly – Inspection – packaging, which is a general process of processing.

Mechanical processing technology is to change the shape, size, relative position and nature of the production object on the basis of the process to make it a finished product or semi-finished product. It is a detailed description of each process. For example, as mentioned above, rough machining may include blank manufacturing, grinding, etc. finishing may be divided into turning, fitter, milling machine, etc., and each step should be detailed Fine data, such as how much roughness to achieve, how much tolerance.

According to the quantity of products, equipment conditions and the quality of workers, technicians determine the technological process to be adopted, and write the relevant contents into process documents, which are called process procedures. This is more targeted. Every factory may be different, because the actual situation is different.

Advantages of CNC machining compared with NC machining

The so-called five axis machining here means that there are at least five coordinate axes (three linear coordinates and two rotation coordinates) on a machine tool, and the machining can be carried out simultaneously under the control of computer numerical control (CNC) system. Compared with the general three axis NC machining, this kind of five axis CNC machining has the following advantages:

1、 It can process continuous and smooth free-form surface which can not be machined by general three-axis or it is difficult to finish machining by clamping at one time. For example, the blades of aeroengine and steam turbine, the screw propeller used in naval ships, and many shells and moulds with special curved surfaces, complex cavities and holes, etc. for example, with the ordinary three-axis numerical control, because the pose angle of the cutter relative to the workpiece cannot be changed in the process of machining, there may be interference or under machining (that is, the machining can not be achieved) when machining some complex free-form surfaces. When machining with five axis linkage machine tool, the tool / workpiece pose angle can be adjusted at any time in the process of processing, so that the interference of tool and workpiece can be avoided and all machining can be completed at one time;

2、 It can improve the machining accuracy, quality and efficiency of free-form surface. For example, ball end milling cutter is often used when machining complex curved surface by three-axis machine tool. Ball end milling cutter is formed by point contact, and the cutting efficiency is low. Moreover, the pose angle of cutter / workpiece cannot be adjusted in the process of machining. Generally, it is difficult to ensure that the best cutting point on the ball end milling cutter (i.e. the highest linear speed point on the ball head) is used for cutting, and it is possible that the cutting point falls on the ball end cutter, and the line speed of the ball end cutter is equal to The situation on the center line of rotation of zero. However, if the five axis machine tool is used, because the position and attitude angle of the tool / workpiece can be adjusted at any time, this situation can not only be avoided, but also the best cutting point of the tool can be made full use of at all times, or the ball end milling cutter formed by point contact can be replaced by the spiral end milling cutter formed by point contact, and even milling can be carried out by further optimizing the pose angle of the cutter / workpiece In order to obtain higher cutting speed and line width, higher cutting efficiency and better surface quality can be obtained.

3、 Advantages of mold processing. In the traditional mold processing, the vertical machining center is generally used to complete the milling of the workpiece. With the continuous development of mold manufacturing technology, some weaknesses of the vertical machining center become more and more obvious. Ball end milling cutter is widely used in modern mold processing. The advantages of ball end milling cutter in mold processing are obvious. However, if the vertical machining center is used, the linear speed of the bottom surface is zero, so the bottom surface finish is very poor. If the four or five axis linkage machine tool processing technology is used to process the mold, the above shortcomings can be overcome. The use of five axis machine tool processing mold can quickly complete the mold processing, fast delivery, better guarantee the mold processing quality, make the mold processing easier, and make the mold modification easier