Monthly Archive July 27, 2019

General Knowledge of CNC Machining

CNC Truning repetitive parts put into production: the use of CNC grinder process preparation time comrade-in-arms higher proportion. For example, preparation of process analysis, programming, adjustment and trial-cutting of Parts’first parts, etc., the sum of these comprehensive working hours is often tens to hundreds of times of the working hours of Parts’ single-part processing, but the working contents of these CNC lathes can be saved and reused, so when a part is successfully manufactured on a CNC grinder and put into production again and again. The production cycle is greatly reduced, the cost is reduced, and good economic benefits can be obtained.

It is required that the key parts of medium and small batches produced with high quality and high efficiency should be processed: CNC grinding machine can realize high precision, high quality and high efficiency grinding under the control of computer. Compared with the special grinding machine, it can save a lot of special process equipment, has a strong flexible manufacturing ability and obtains better economic benefits. Compared with ordinary grinding machine, it can eliminate many human interference factors in the long process of complex processing, and has good accuracy consistency and interchangeability of parts, and high processing efficiency.

The parts processed by CNC Machine should conform to the technological characteristics that can give full play to the multi-process centralized processing of CNC grinder. When CNC grinder processes parts, the situation of grinding wheel cutting workpiece is exactly the same as that of corresponding non-CNC grinder, but it can carry out some compound processing with the requirement of processing accuracy, such as in the grinding range. Ordinary grinding machine is mainly used to grind cylindrical surface, conical surface of circular NC lathe or end face of stepped shoulder. In addition to NC cylindrical grinding machine, it can also grind ring surface, as well as all kinds of complex combination surface.

The processing batch of parts should be larger than that of ordinary lathe batch CNC lathe in non-CNC grinder processing, small batch parts. For various reasons, the pure cutting time only accounts for 10%-30% of the actual working hours. When processing on CNC grinder with multi-process centralization such as grinding processing center, this proportion may rise to 70%-80%. But preparing to adjust the working hours is often much longer, so it will become uneconomical when the batch size of parts is too small.

Considering the processing of some special parts processed by CNC NC lathe, although some parts are processed in small batches, ordinary lathes have complex shapes, high quality and good interchangeability, which can not meet the above requirements on non-CNC grinders, and can only be processed on CNC grinders, such as parabola, cycloidal cams and special ones. The mirror of the surface, etc.

An Overview of Automobile Dies

The main component of automobile die is panel die. This kind of die is mainly cold stamping die. In a broad sense, “automobile die” is the general name of the die for manufacturing all parts of the automobile. For example, stamping mold, injection mold, forging mold, casting wax mold, glass mold and so on.

The stamping parts of automobile body are generally divided into covering parts, beam frame parts and general stamping parts. The stamping parts which can clearly express the image characteristics of automobile are automobile panels. Therefore, the more specific automobile die can be said to be “automobile panel stamping die”. Abbreviated as automobile panel die. For example, the trimming die for the front door outer panel, the punching die for the front door inner panel, etc.

Of course, not only the body of the car has stamping parts. Dies for all stamping parts on automobiles are called “automobile stamping dies”. To sum up, it is:

1. The automobile die is the general name of the die for manufacturing all the parts on the automobile.

2. The automobile stamping die is the die for stamping all the stamping parts on the automobile.

3. The stamping die for automobile body is the die for stamping all stamping parts on automobile body.

4. The stamping die for automobile panels is the die for stamping all automobile panels.

Now, when we talk about automobile die, it seems that we all refer to automobile panel die. In order not to be confused with the generalized automobile die, it is better to use automobile panel die instead of automobile die when posting.

There are many kinds of stamping dies. The stamping dies are classified according to their working properties, die structure and die materials.

Generally, it can be classified according to the following main features:

1. Classification according to process properties

A. Punching Die: Die that separates materials along closed or open contours. Such as blanking die, punching die, cutting die, cutting die, trimming die, cutting die, etc.

B. Bending die: A die that bends a blank or other blank along a straight line (bending line) to obtain a workpiece with a certain angle and shape.

C. Deep drawing die: a die that makes a blank of a sheet into an open hollow part or makes the hollow part change its shape and size further.

D. Forming die: a die that directly reproduces the shape of the convex and concave die of a blank or semi-finished product according to the figure, while the material itself produces only local plastic deformation. Such as bulging die, necking die, expanding die, undulating forming die, flanging die, shaping die, etc.

2. Classification according to the degree of process combination

A. Single process die: In one stroke of press, only one stamping process is completed.

B. Compound die: a die with only one working station, which can complete two or more stamping processes at the same working station in one stroke of the press.

C. Progressive Die (also called Continuous Die): In the direction of blank feeding, there are two or more positions. In one stroke of press, two or more stamping processes are completed at different positions one by one.

3. Classification according to the processing method of products

According to the different processing methods of products, the dies can be divided into five categories: punching and shearing dies, bending dies, drawing dies, forming dies and compression dies.

A. Punching and shearing dies: the work is completed by shearing. The common forms are cutting die, blanking die, punching die, trimming die, flanging die, drawing die and punching die.

B. Bending die: It bends flat hair embryo into an angle shape, depending on the shape, accuracy and production of the parts, it has many different forms of die, such as ordinary bending die, cam bending die, crimping die, arc bending die, bending punch and twisting die.

C. Pumping Die: Pumping Die is a seamless container made of flat hair germ.

D. Forming die: refers to the use of various local deformation methods to change the shape of the hair embryo, in the form of convex forming die, flange forming die, necking forming die, hole flange forming die, flange forming die.

E. Compression die: It uses strong pressure to make the metal hair germ flow and deform into the required shape. Its types include extrusion die, embossing die, embossing die and end-pressing die.


Effect of 1 Nickel on Microstructure

Nickel is an element that strongly stabilizes austenite and enlarges austenite phase region. In order to obtain a single austenite structure, the minimum nickel content required for steel containing 0.1% carbon and 18% chromium is about 8%. This is the basic component of the most famous 18-8 chromium-nickel austenitic stainless steel. With the increase of nickel content in austenitic stainless steel, the residual ferrite can be completely eliminated and the formation of_phase can be significantly reduced. At the same time, the temperature of martensite hydrocarbon conversion decreases, and even the transformation of lambda to M does not occur, but the increase of nickel content will reduce the solubility of carbon in austenitic stainless steel, thus increasing the tendency of carbide precipitation.

Effect of 2-Nickel on Properties

The effect of nickel on the mechanical properties of austenitic stainless steel, especially chromium-nickel austenitic stainless steel, is mainly determined by the effect of nickel on the stability of austenite. Within the range of nickel content which may occur martensitic transformation in steel, with the increase of nickel content, the strength of steel decreases and the plasticity increases, and the toughness of chromium-nickel Austenitic STAINL ) It is well known that nickel can be used as a cryogenic steel because of its excellent properties. For Chromium-Manganese austenitic stainless steel with stable austenite structure, the addition of nickel can further improve its toughness. Nickel can also significantly reduce the cold work hardening tendency of austenitic stainless steel, which is mainly due to Austenite Stability increasing, reducing or even eliminating martensite transformation during cold work. At the same time, the cold work hardening effect of austenite itself is not obvious. The influence of nickel on the cold work hardening tendency of stainless steel reduces the cold work hardening rate of austenitic stainless steel and the room temperature of steel. The increase of nickel content is conducive to the cold working formability of austenitic stainless steel, and the increase of nickel content can also reduce and even eliminate the delta ferrite in 18-8 and 17-14-2 chromium-nickel austenitic stainless steel, thus improving its hot working performance. However, the decrease of delta ferrite is not conducive to the weldability of these steels and will increase the inclination of welding hot crack wires. In addition, nickel can also significantly improve the hot working performance of chromium-manganese-nitrogen (chromium-manganese-nickel-nitrogen) austenitic stainless steel, thereby significantly improving the yield of steel. In austenitic stainless steel, the addition of nickel and the increase of nickel content lead to the increase of the thermodynamic stability of steel. Therefore, austenitic stainless steel has better properties of stainless steel and oxidation resistance medium, and with the increase of nickel It is worth pointing out that nickel is also the only important element for austenitic stainless steel to improve its resistance to transgranular stress corrosion in many media. The effect of nickel on the corrosion resistance of austenitic stainless steel in various acid media needs to be pointed out that under some conditions of high temperature and high pressure water, the increase of nickel content leads to intergranular stress corrosion of steels and alloys. With the increase of nickel content in austenitic stainless steel, the critical carbon content for intergranular corrosion decreases, that is, the sensitivity of steel to intergranular corrosion increases. As for the resistance to pitting corrosion and crevice corrosion of austenitic stainless steel, the effect of nickel is not significant. In addition, nickel also improves the high temperature oxidation resistance of austenitic stainless steel, which is mainly due to the improvement of the composition, structure and properties of chromium oxide film by nickel, and the higher the nickel content, the more harmful it is. This is mainly due to the low melting point nickel sulfide at the grain boundary of steel. Generally speaking, simple chromium-nickel (and chromium-manganese-nitrogen) austenitic stainless steel is only used to require stainless and oxidation resistant medium Molybdenum, as an important alloying element in austenitic stainless steel, is added to steel to further expand its application range. The main function of molybdenum is to improve the reduction medium of steel.

Sharing Some Operational Skills and Experiences of CNC Turning Machining

In CNC Turning processing, many places need to concentrate on manipulation, so as to prevent some unnecessary problems in the process of manipulation, thereby delaying the progress of work and affecting the efficiency of all work. Underneath, let Xiaobian explain some manipulation skills and experience of CNC Turning for everyone! Let’s learn together.

I. Programming Techniques

1. Processing sequence of parts:

Drilling first and then flat end (this is to prevent shrinkage during drilling);

First roughing, then finishing (this is to ensure the accuracy of parts);

The first step is to process the larger part and the smaller part (which ensures that the surface of the size of the smaller part is not scratched and prevents parts from deforming).

2. Choose the correct rotational speed, feed rate and cutting depth according to the hardness of raw materials.

1) Carbon steel raw material selection of high speed, high feed, large depth of cut. For example: 1Gr11, S1600, F0.2 and 2 mm cutting depth were selected.

2) Cemented carbide should be selected with low speed, low feed and small depth of cut. For example: GH4033, select S800, F0.08 and cut depth 0.5mm;

3) Titanium alloy should be selected with low speed, high feed rate and small cutting depth. For example: Ti6, choose S400, F0.2 and 0.3mm cutting depth. Take the processing of a part as an example: the raw material is K414, which is a special hard raw material. Through repeated tests, S360, F0.1 and 0.2 cutting depth are selected to produce qualified parts.

2. Knife-setting Techniques

Tool alignment is divided into tool alignment instrument and direct tool alignment. Most lathes in our factory have no tool alignment instrument. For direct tool alignment, the following knife alignment technique is direct tool alignment.

Firstly, the center of the right end face of the part is chosen as the cutter point and set to zero. When the machine tool returns to the origin, the center of the right end face of the part is the zero point for each cutter to be used. When the cutter touches the right end face and inputs Z0 click measurement, the cutter compensation value of the cutter will automatically record the value of measurement, which means that Z-axis cutter alignment is good, X-cutter alignment is the trial cutter, and the outer circle of the part is turned with the cutter. Less, the measurement is inputted into x 20 by the value of the outer circle of the car (e.g. x is 20 mm). Click on the measurement, and the cutter compensation value will automatically record the measured value. At this time, the x-axis is also good. This tool alignment method, even if the machine is powered off and the call is restarted, will not change the tool alignment value. It can be applied to large quantities of long-term light production of the same parts, during which no need to turn off the lathe from scratch.

3. Debugging Techniques

In order to prevent errors in the procedure and errors in tool setting and collision, we should first simulate the empty travel, and move the total length of the part to the right in the coordinate system of the machine tool 2-3 times as long as the tool, and then start the simulated processing, confirm the correctness of the program and tool setting after the imitation processing is completed, and then confirm the correctness of the program and tool setting after the imitation processing is completed. The first part is processed. After the first part is processed, the first part is self-checked, confirmed and passed. Then the professional check is found. Only after the professional check is confirmed, the debugging is finished.

4. Experience in preventing collision of machine tools

Machine tool collision has a great impact on the accuracy of machine tools. The impact on different types of machine tools is also different. Generally speaking, the impact on machine tools with weak rigidity is greater. So for high precision CNC lathe, the collision must be absolutely prevented. As long as the operator carefully manages the positive anti-collision way, the collision can be prevented and prevented completely.

The main reasons for the collision are as follows: first, the input errors of tool diameter and length; second, the input errors of workpiece size and other related geometric dimensions and the positioning errors of initial position of workpiece; third, the configuration errors of workpiece coordinate system of machine tool, maybe the zero point of machine tool is reset in the process of machining, and the change occurs. The collision of machine tool mostly occurs in the process of rapid movement of machine tool. At this time, the collision hazards are also great and should be absolutely prevented. Therefore, the operator should pay special attention to the machine tool in the initial stage of the implementation of the program and the machine tool in the time of tool replacement. Once the program compilation error, tool diameter and length input error, then it is very easy to collide. At the end of the program, the cutter withdrawal behavior of NC axis is sequential error, then collision may occur.

In order to prevent the collision mentioned above, the operator should fully develop the performance of the five senses when operating the machine tool, and watch whether the machine tool has extraordinary behavior, sparks, noise and extraordinary noise, sensation and burning odor. If the special situation is found, the program should be stopped immediately, and the machine tool can continue to work only after the problem of the machine tool has been solved.

Only by concentrating on accurate manipulation can we prevent the impact of manipulation errors. We trust that people have learned a lot from the beginning and end of this article. Welcome to continue to pay attention to us. We will periodically launch this kind of knowledge of CNC lathe processing and manipulation for everyone to learn.

Development Trend of Gantry Milling in the Future

Gantry milling has occupied an important position in mechanical processing equipment. With the continuous development of science and technology, the current gantry milling technology and equipment has been in the process of high efficiency, high security and intelligence. What is the future development trend of gantry milling?

1. Functional Development Trend

CNC system is an important part of gantry milling. Operators operate CNC system through user interface to control large-scale CNC gantry milling to process workpieces. Because different users have different requirements for the interface, the workload of developing user interface is huge. User interface has become the cause of computer software development. One of the difficult parts is that the emergence of GUI greatly facilitates the use of non-professional users. People can operate through windows and menus to facilitate blueprint programming and rapid programming, three-dimensional color stereo dynamic graphics display, graphics simulation, graphics dynamic tracking and simulation, different directions of view and local display ratio. The implementation of the example scaling function. With the updating of CNC system and the upgrade of user interface, the function of gantry milling will be further developed in the future.

Gantry milling

2. Performance Development Trend

Efficiency, speed and accuracy are the key performance indicators of mechanical processing. High-speed CPU chip, multi-CPU control system and AC digital servo system are used in gantry milling. Meanwhile, measures such as improving dynamic and static characteristics of machine tools are taken to improve the speed efficiency and accuracy of gantry milling. At present, the MTBF value of CNC devices used in gantry milling equipment abroad can reach more than 6000h, and the MTBF value of servo system can reach more than 30000h, which has high reliability. With the development of science and technology in the future, CPU chip will achieve higher speed, servo system will be more perfect, and the performance of gantry milling will be improved greatly.

3. Structural Development Trend

At present, the gantry milling process uses highly integrated CPU/RISC chip, large-scale programmable integrated electric field programmable gate array/EPLD/CPLD and ASIC chip, which can improve the integration of CNC system and the speed of software and hardware operation. The application of FPD flat panel display technology can improve the performance of display. Flat panel display has the advantages of high technology content, light weight, small size, low power consumption and easy to carry. It can realize large-scale display and become a new display technology to compete with crt. It is the mainstream of display technology in the 21st century. Semiconductor and surface mounting technology are integrated to reduce product price, improve performance, reduce component size and improve system reliability by increasing IC density, reducing interconnection length and number. With the further development of intelligent technology, the volume of chips and integrated circuits will be smaller, and the structure of gantry milling equipment will be improved greatly.

With the continuous exploration of human beings, the development of science and technology will be unlimited, and the future of gantry milling will also get greater development. The future intelligent world will make gantry milling more intelligent.

What are the factors affecting the precision of precision parts

What are the factors that affect the precision of precision parts? As we all know, the reason why precision parts processing is called precision mechanical processing is precisely because of its high processing process and process requirements and the high precision requirements of products. The precision of precision parts processing includes the accuracy of position, size and shape, etc. We summarize the following factors that affect precision. The factors affecting the precision of dense parts processing are as follows:

(1) The inaccuracy of machine tool guideway can also lead to the error of workpiece shape in precision parts processing.

(2) The spindle rotational jump energy of machine tool produces certain errors in the processing accuracy of parts.

(3) Drive parts can also cause errors in workpiece processing, which is also the main factor of workpiece surface errors.

(4) The different types of tools and fixtures also have different effects on the accuracy of the workpiece.

(5) In the process of machining and cutting, the system will be deformed due to the change of the position of the stress point, which will lead to the difference, and also make the accuracy of the workpiece produce different degrees of error.

Precision Parts Processing

(6) The different cutting force will also affect the accuracy of the workpiece.

(7) The error caused by the thermal deformation of the process system. In the process of mechanical processing, the process system will produce certain thermal deformation under the action of various heat sources.

(7) Deformation caused by heating of the process system often affects the accuracy of the workpiece.

(8) Deformation caused by machine tool heating will lead to deformation of workpiece.

(9) The thermal deformation of the tool will have a great impact on the workpiece.

(10) The workpiece itself is deformed by heat, mainly in the process of cutting.

Explain matters needing attention in CNC Machining

oday, we will introduce the precautions for CNC Machining:

When choosing a knife point, the knife path can be laid at any designated height and position. When the first knife is first processed, the amount of knife eaten is often large, which can easily lead to broken knives and bullet knives. At this time, the lower knife position can be roughened or the first layer of the lower knife can be empty, and the knife can be laid outside the material as far as possible. This problem must be noticed.

2. Knife grabbing, marble knife, tool dropping, large feed volume, long clamping length and small tool diameter often occur. When the corner radius and tool radius are in the same position, inaccurate shape and size are easy to occur. Knife grabbing is called knife grabbing, which can be solved by layering and clearing the angle with a smaller diameter knife, and then changing the smooth side of the larger knife. Definitely. When the depth is low and large, it can be processed by layers.

3. Overcut inspection and overcut are common problems, which should be paid special attention to. The solution is to simulate the tool path once and check it repeatedly from various angles of view. The tool path without inspection is not allowed to be machined. In profile milling, inappropriate selection of cutter point will lead to over-cutting, which can be avoided by changing the cutter point.

The above attention about CNC Machining is introduced here, I hope it will be helpful to you.

What is CNC Machining

Generally CNC Machining usually refers to precise machining controlled by computer digitally, CNC Machining lathe, CNC Machining milling machine, CNC Machining boring and milling machine, etc. CNC, also known as computer gongs, CNCCH or CNC machine tools, is actually a term used in Hong Kong. Later, it was introduced into the Pearl River Delta of the mainland. In fact, it is a CNC milling machine. In Guangzhou, Jiangsu, Zhejiang and Shanghai, CNC machining center is a new type of processing technology. Its main task is to compile processing procedures, which will be the original manual work. Turn to computer programming. Of course, there is a need for manual processing experience.

CNC  machining has the following advantages:

The number of tooling is greatly reduced, and complex tooling is not needed to process parts with complex shapes. If you want to change the shape and size of the parts, you only need to modify the parts processing procedures, which is suitable for the development and modification of new products.

The processing quality is stable, the processing accuracy is high, and the repetition accuracy is high, which meets the processing requirements of aircraft.

In the case of multi-variety and small batch production, the production efficiency is higher, the time of production preparation, machine tool adjustment and process inspection can be reduced, and the cutting time can be reduced by using the best cutting quantity.

It can process complex profiles which are difficult to be machined by conventional methods, and even some parts which can not be observed.

This is the end of the above introduction about CNC processing. I hope it will be helpful to you.

Common CNC Machining Center Servo System Faults

The fault forms of CNC machining center servo system include alarm light on speed unit, fuse and jump switch for various protection. The meaning of alarm light varies with the design of speed control unit. Generally, there are the following kinds:

1. High current causes machine tool alarm. In general, there are two possibilities for high current alarm, that is, the damage of power drive components in NC speed control unit of machining center and the high current alarm caused by short circuit.

2. High voltage will also lead to machine tool alarm. There are three kinds of situations where high voltage alarm occurs. It may be that the CNC input voltage of the machining center exceeds 10% of the rated value, or the insulation performance of the servo motor decreases, or the high voltage caused by the circuit of the speed control unit of the machining center.

3. Too low voltage leads to machine tool alarm. The probability of this happening in the machining center is very small. It may be that the input voltage is lower than 85% of the rated value, or the power connection is not good.

4. Feedback line break of detection speed leads to alarm, which is an error alarm, because the airport is not a problem, and there are problems in the detection and feedback system. Most of these alarms are caused by speed feedback line break of CNC servo motor in machining center or bad contact of its detection and feedback line.

5. Protective switch start alarm. Protective switch is a kind of device to protect machine tools. For example, high voltage will burn some components and other emergency measures that machine tools can not control. When encountering these situations, the protective switch will start to avoid unnecessary component damage, similar to safety stop and so on.

6. Overload alarm, the causes of overload alarm are abnormal load of CNC machine in machining center, or too low upper limit of motor current in speed control unit. Permanent magnet shedding on permanent magnet motor can also cause overload alarm. If the CNC motor without brake is idle, it is hard to rotate by hand or to rotate the axis, that means permanent magnet shedding completely.

7. Fuse burning or circuit breaker tripping on CNC speed control unit of CNC machining center.

How to Guarantee the Precision of CNC Machining

In the machining center, the CNC lathe generally needs to use more than one tool, so we should arrange the processing order reasonably, which is conducive to improving the processing accuracy, processing power and economic benefits. When arranging the NC lathe processing order, we should follow the general technological principles of “base plane first”, “face first, face first”, “primary and secondary” and “roughness first, refinement later”.

The selection of positioning datum directly affects the arrangement of processing order. As a positioning datum, the surface should be processed well in order to provide a reliable positioning datum for other processing areas. Because the surface machined by this process after selecting the positioning datum may be the positioning datum of the next process, after the determination of the positioning datum of each process, the roughly second order of the whole process can be deduced step by step from the finishing process after all.

When deciding the processing order of NC lathe, it is necessary to clarify whether the parts should be pre-processed before processing. Prefabrication usually ends with a general machine tool. If the precision of the blank is higher, the positioning is more reliable, or the processing margin is sufficient and uniform, it can be processed directly on the processing center instead of pre-processing. At this time, according to the accuracy of rough benchmark, we should consider the difference of the process of machining center, so one process or several dividend processes can be completed.

When CNC lathe processes parts, it is difficult to guarantee the standard between the machined and non-machined surfaces, which is the same as CNC milling. Therefore, even if the right and wrong processing surface is required by the drawing, the appropriate margin must be added to the non-processing surface when making the blank, so as to ensure that the standard between the non-processing surface and the processing surface meets the drawing requirements in the machining center.

Similarly, if there is a standard requirement between the pre-fabricated surface before CNC lathe processing and the faceted surface processed by CNC machining center, a certain amount of processing allowance should be left during pre-fabrication, and all processing contents including pre-faceted surface should be finished in a clamp of the machining center.