September 2020 – Page 36 – CNC Machining & Turning, Milling, Metal parts

How to set the reference point and coordinate of NC lathe in NC machining?

You can see if your bed reference point parameters are set correctly.

Generally, CNC cutting system automatically processes the parts to be processed according to the pre programmed processing program (commonly used drawing software aotocad). According to the instruction code and program format specified by the NC cutting system, a machining program sheet is compiled for the machining process route, process parameters, tool movement path, displacement, cutting parameters (spindle rotation, feed rate, back feed, etc.) and auxiliary functions (tool change, spindle forward rotation, reverse rotation, cutting fluid on and off, etc.), and then record the contents of this program list in the NC cutting system Control medium (such as perforated paper tape, magnetic tape, magnetic disk, magnetic bubble memory), and then input into the numerical control device of the numerical control machine tool, so as to direct the machine tool to process parts.

The whole process from analysis of part drawing to making control medium is called NC programming. The difference between CNC cutting equipment and ordinary hand and semi-automatic cutting equipment in processing parts is that CNC cutting equipment automatically processes parts according to the program, while ordinary hand and semi-automatic cutting equipment needs to be operated by people. We can achieve the purpose of processing different parts as long as we change the program that controls the action of the machine tool. Therefore, CNC cutting equipment is particularly suitable for processing small batch and complex shape parts with high precision requirements!

Because the CNC cutting equipment must process parts according to the program, the programmer will input the program into the CNC system to direct the work of the machine tool. The program input is through the control medium. In this way, the NC system is used to control and complete the processing of parts. The drawing staff can modify the graphics in time, and the accuracy of the parts is greatly improved compared with that of the semi-automatic cutting equipment!

What are the contents of process analysis of part drawing in NC machining?

In the process of NC process analysis, first of all, the process analysis of the part drawing should be carried out to analyze whether the structural process of each part of the part conforms to the characteristics of NC machining

1. The dimension marking of part drawing should conform to the convenience of programming

In the NC machining drawing, it is better to use the same datum to quote the dimension or give the coordinate size directly. This marking method is not only convenient for programming, but also convenient for coordinating the setting and calculation of design datum, process datum, testing datum and programming zero point.

2. The geometric element conditions of the contour structure of parts should be sufficient

In programming, all geometric elements that constitute the contour of the part should be defined. When analyzing the part drawing, it is necessary to analyze whether the conditions of various geometric elements are sufficient. If not, it is impossible to program or model the parts to be processed.

3. Can machining accuracy and dimensional tolerance required by parts be guaranteed

Although the machining accuracy of CNC machine tools is very high, for some special cases, such as the processing of thin-walled parts, due to the poor rigidity of thin-walled parts, the cutting force generated during machining and the elastic yielding of thin-walled parts are easy to produce vibration of the cutting surface, which makes the dimensional tolerance of thin-walled thickness difficult to guarantee, and its surface roughness also increases When its thickness is less than 3 mm, we should pay attention to this problem in technology.

4. Are the geometric types and dimensions of the internal and external contour of the part unified

In NC programming, if the geometric types of the inner contour and outer contour of the part are the same or similar, consider whether it can be programmed in the same program to reduce the tool specification and tool change times as far as possible, so as to reduce the auxiliary time and improve the machining efficiency. It should be noted that the diameter of the tool is often limited by the radius r of the inner contour arc.

5. Can larger diameter tools be used in the process structure design of parts

Using larger diameter milling cutter to process can reduce the number of tool passes and improve the tool rigid system. Not only the machining efficiency is improved, but also the processing quality of the surface and bottom surface of the workpiece is also improved.

6. The fillet radius of the groove bottom or the fillet radius r at the intersection of the base plate and the edge plate should not be too large

Because the large diameter of the cutter contacting with the milling plane D = d-2r, where D is the diameter of the milling cutter. When D is constant, the larger the fillet radius R (as shown in Fig. (1), the worse the ability of milling cutter end edge to mill plane, the lower the efficiency and the worse the manufacturability.. When R reaches a certain degree, it must be processed with ball end milling cutter, which should be avoided. When D is larger and R is smaller, the area of milling surface is larger, the ability of machining plane is stronger, and the milling technology is better. Sometimes, when the bottom surface area of milling is large and the bottom arc R is also large, two milling cutters with different R can be used to cut twice.

7. Principle of ensuring the unification of standards

If the parts are re installed on the other side after milling one side, due to the non-uniform datum, it is often difficult to connect the cutter due to the re installation of the parts, and the contour position and size on the positive and negative sides are not coordinated after machining. Therefore, it is necessary to make full use of the appropriate hole of the part itself or the reference edge of the part contour or specially set the process hole (such as adding process boss on the blank or setting the reference hole on the allowance to be removed in the subsequent process) as the positioning reference, so as to ensure the accuracy of the relative position after two clamping processes.

8. Consider the deformation of parts

When the parts are deformed in the process of NC milling, not only the machining quality of the parts is affected, but also the phenomenon of skipping cutter sometimes occurs. At this time, we should consider the milling process, separate the rough and finish machining as far as possible, or use the symmetrical method to remove the allowance. Of course, heat treatment can also be used to solve the problem.

Analysis of automobile parts processing flow

1、 Drawing design, drawing is the initial part of a part, is designed according to the requirements of customers, so that customers can trust you more.

2、 Material selection, when we are processing, we will select the material suitable for it for processing, so what material is suitable for it? In fact, the material can be said to be the core product of the whole part, so it must be carefully selected.

3、 Programming, CNC lathe is a new type of equipment that can realize automatic production. At present, this equipment can realize full-automatic production and save a lot of unnecessary expenses. It can be said that it is a pure cost-saving mechanical equipment.

4、 No matter what parts are processed, the steps must be carried out according to the conventional process. It is not allowed to change the processing steps at will. Any mistakes in this step will affect the bending of the whole part.

Parts processing

The above processes can be said to be the process of NC machining of automobile parts, which must be carried out according to the overall process. Therefore, the process is the core of parts processing and the capital that can be expanded infinitely in the industry.

报错笔记

Summary of automobile parts processing technology

A car is composed of many parts, each part plays a different role, and it needs to be processed through different processing technology, and then it can be installed on the car for use. What are the processing technologies of automobile parts?

1、 Forging of automobile parts

Forging is widely used in automobile manufacturing. Forging methods are divided into free forging and model forging. Free forging is a method of forming metal blank on anvil under impact or pressure. The blank of automobile gear and shaft is processed by free forging.

2、 Casting processing of automobile parts

Casting is a production method in which molten metal is poured into the mold cavity and cooled and solidified to obtain products. In the process of automobile parts processing and manufacturing, there are many parts made of cast iron, which account for about 10% of the whole vehicle weight, such as air cylinder block, transmission box, steering gear housing, rear axle housing, brake drum, various supports, etc.

Sand mold is usually used to make iron castings. The raw material of sand mold is mainly sand, mixed with binder and water. The sand mold material must have a certain adhesive strength, so that it can be molded into the required shape and can resist the erosion of hot metal without collapse. In order to form a cavity in the sand mold in accordance with the shape of the casting, it is necessary to make a model of wood, called wood mold. The volume of hot molten iron will be reduced after cooling. Therefore, the size of wood mold should be increased according to the shrinkage rate based on the original size of the casting, and the surface to be machined should be thickened accordingly.

3、 Welding processing of automobile parts

Welding is a processing method that two pieces of metal are locally heated or simultaneously heated and pressurized. We often see workers holding a mask in one hand and welding tongs and welding rods connected with wires in the other hand. The welding method is called manual arc welding, which uses the high temperature generated by arc discharge to melt the welding rod and weldment and make them join.

Manual arc welding is not widely used in automobile manufacturing. Spot welding is widely used in automobile body manufacturing. Spot welding is suitable for welding thin steel plates. During operation, two electrodes apply pressure to two steel plates to make them stick and merge. At the same time, the bonding point (circle with a diameter of 5-6 μ m) is heated and melted by electric current, so as to firmly join. When two body parts are welded, a point is welded at the edge every 50-100 ° to form a discontinuous multi-point connection. It usually takes thousands of solder joints to weld the whole car body. The strength requirement of solder joint is very high, each solder joint can bear 5kn tensile force, even tear the steel plate, but the solder joint can not be separated.

4、 Cold stamping of automobile parts

Cold stamping or sheet metal stamping is a processing method to make the sheet metal be cut off or formed under pressure in the die. Daily necessities, such as aluminum pot, lunch box and washbasin, are made by cold stamping. For example, to make a lunch box, the first step is to cut out a rectangular blank with four rounded corners (referred to as “blanking” in the industry), and then the blank is pressed into the female die with a punch to form (referred to as “drawing” in the industry). In the drawing process, the flat sheet metal becomes a box shape, and its four sides are vertically bent upward, and the materials at the four corners accumulate and wrinkles can be seen.

5、 Automobile parts cutting

Automobile parts cutting is a kind of machining method which uses cutting tool to cut the metal blank layer by layer, so that the workpiece can get the required shape, size and surface roughness. Metal cutting includes fitter and mechanical machining. Fitter is a kind of machining method that workers use manual tools to cut. It is flexible and convenient to operate, and it is widely used in assembly and repair. Mechanical processing is completed by means of machine tools, including turning, planing, milling, drilling and grinding.

6、 Heat treatment of automobile parts

Heat treatment is a method to change the structure of solid steel by reheating, holding or cooling, so as to meet the use requirements or process requirements of parts. Different microstructure changes can be produced by heating temperature, holding time and cooling rate. The hardness of the steel parts can be improved by immersing the heated steel parts in water for rapid cooling.

Matters needing attention in CNC machining of aluminum alloy

With the advent of the industrial 2.0 era, China’s manufacturing industry is generally growing, and the requirements for the processing and manufacturing industry are higher. Taking the aluminum parts processing and manufacturing industry as an example, the CNC machining accuracy of aluminum alloy is more stringent. However, this is also the trend of the times. It is obvious that aluminum parts are widely used in high-precision instruments. The following Ju Sheng Yuan hardware products small for everyone to chat about the aluminum alloy CNC processing need to pay attention to.

1. The speed of white steel knife should not be too fast.

2. When the workpiece is too high, please thicken it with a knife of different grade length.

3. After roughening with a rough knife, remove the excess with the knife, and grind the knife after ensuring the excess.

4. The plane is processed with flat bottom edge instead of ball edge to reduce processing time.

5. The four corners of the calibration plane must be flat.

6. The inclination is an integer, which is processed with an inclined cutter, such as tube position.

7. Before each work, want to clear the remaining amount of the previous work after processing, to avoid empty tool and redundant processing.

8. Try to take a simple path. For example, shape, trenching, avoiding single side, lapping, etc.

9. When taking wcut, if you can go to finish, please don’t take rough.

10. In the case of shape light knife, the light should be coarsened first and then exposed. When the workpiece is too high, it should be illuminated first and then.

11. The tolerance should be set reasonably to balance the machining accuracy and computer calculation time. The tolerance is set to 1 / 5 of the remaining value when it is turned on, and 0.01 for a light knife.

12. Add more projects to reduce the time of empty knife. Think more and reduce the chances of mistakes. Increase the auxiliary surface of the auxiliary line slightly to improve the processing condition.

The above is jushengyuan hardware products Xiaobian summed up aluminum alloy CNC processing precautions, I believe that CNC processing enthusiasts will operate CNC processing process will encounter. If you encounter any problems in CNC processing of aluminum alloy, please leave a message below.

CNC machining principle and advantages of aluminum alloy

CNC machining of aluminum alloy, also known as computer gong processing or CNC machine tool processing, mainly aluminum parts, aluminum shell and other aspects of processing. In recent years, due to the high-precision processing of aluminum alloy and aluminum alloy, the high-precision processing technology of aluminum alloy and aluminum alloy has been greatly improved.

1、 CNC machining principle of aluminum alloy:

The CNC machining principle of aluminum alloy is to install digital program flow command to control the bearing automatic start stop, change direction and speed change of CNC machine tool. The NC blade can be selected, and the cutting amount and walking track can be changed according to the NC blade to complete all kinds of auxiliary actions needed in the life-long machining.

2、 Advantages of CNC machining of aluminum alloy:

① CNC machining of aluminum alloy can reduce the total number of tooling in large quantities, and produce complex parts and components, only need to change the process flow.

② CNC machining of aluminum alloy is relatively stable, which will not cause deviation in manual processing, resulting in different aluminum alloy and even defective products.

③ CNC machining of aluminum alloy can produce complex aluminum parts, and even can produce processing parts. It can also produce a variety of varieties, high production efficiency, save labor costs, and realize multiple and large-scale production at the same time.

The above is the principle and advantages of aluminum alloy CNC processing, is jushengyuan hardware products small series, accumulated several years of aluminum alloy CNC processing experience. For aluminum alloy CNC processing and do not understand, can come to consult, there will be unexpected harvest.

Characteristics of CNC machining process for aluminum alloy

The requirement of CNC machining technology for aluminum alloy is that the control system can use control code or other symbol instruction rules to process the program logically, decode the program by computer, and then make the machine move and process parts. After cutting tools, the blank is processed into semi-finished parts, etc. Numerical control cutting is not only a reasonable processing method, but also a common process of aluminum alloy precision machining. Vertical milling cutter, spiral interpolation and contour cutting interpolation with multi-directional cutting function are selected, and a small number of holes are processed with fewer cutters.

CNC machining of aluminum alloy

Ball end milling cutter with spiral interpolation method can be used for continuous processing of conical hole; ball end milling cutter and spiral interpolation bit can be used for boring and chamfering; vertical milling cutter with equal height cutting interpolation can be used for semi precision machining and precision parts processing; end milling cutter with spiral interpolation method for thread processing can process various threaded holes. Assuming that high precision holes of any size are machined by high efficiency aluminum alloy precision parts, the interpolation functions of East and West can be used. Especially when high-speed milling is selected, the load of each tool is relatively light. Therefore, with the same coating cemented carbide end milling cutter, all kinds of processed materials can be processed with high speed and high precision.

Milling cutter

In the CNC machining process of aluminum alloy shell, it is necessary to master the processing skills of processing technology paint. Select a reasonable cutting amount, and select the cutting speed according to the needs of processing materials, hardness, cutting conditions, material types, cutting depth, etc.

These conditions are necessary to reduce machine wear. In general, when using rough turning, it is better to select high-strength cutting tools to better meet the requirements of rough turning. The reasonable selection of fixture parts should fully meet the needs of the machine, so as to reduce unnecessary positioning error, so as to select special fixture to accommodate the items. Acknowledge a reasonable process. Shorten the machining stroke as far as possible and reduce the wear of the machine.

CNC machining shell of aluminum alloy

Peach and plum do not say, their groin. In the actual processing and production process, these advanced CNC machining experience greatly improves the CNC machining and quality of aluminum alloy shell.

What are the principles of CNC processing of aluminum alloy

Compared with manual machining, CNC machining of aluminum alloy has great advantages, such as aluminum alloy parts produced by CNC machining are very accurate and repeatable; CNC machining of aluminum alloy can produce parts with complex shape that cannot be completed by manual processing. What are the principles of CNC processing of aluminum alloy?

CNC machining robot

(1) In order to ensure the CNC machining accuracy of aluminum alloy, roughing and finishing should be carried out separately. During rough machining, the cutting amount is large, the cutting force and clamping force on the workpiece are large, the heat generation is more, and the machining surface has obvious work hardening phenomenon. There is a large internal stress in the workpiece. If the rough machining and rough machining are carried out continuously, the precision of the parts after finishing will be lost quickly because of the redistribution of stress. For some parts with high machining accuracy. After rough machining and before finishing, low temperature annealing or aging treatment should be arranged to eliminate internal stress.

(2) Reasonable selection of CNC processing equipment for aluminum alloy. Rough machining is mainly to cut off most of the machining allowance and does not require high machining accuracy. Therefore, rough machining should be carried out on machine tools with high power and low precision, while the finishing process requires high-precision machine tools. Rough machining and finish machining are processed on different machine tools, which can not only give full play to the equipment capacity, but also extend the service life of precision machine tools.

(3) Heat treatment process is often arranged in CNC process of aluminum alloy. The arrangement of heat treatment process is as follows: in order to improve the cutting performance of metal, such as annealing, normalizing, quenching and tempering, it is generally arranged before machining. In order to eliminate internal stress, such as aging treatment, quenching and tempering treatment, it is generally arranged after rough machining and before finishing. In order to improve the mechanical properties of parts, such as carburizing, quenching, tempering, etc., they are generally arranged after machining. If there is large deformation after heat treatment, Zui finishing process must be arranged.

The correct operation and maintenance is one of the key factors for the correct use of aluminum alloy CNC processing equipment. In the correct operation and use, it can prevent abnormal wear and tear of machine tools and avoid sudden failure; in daily maintenance, the equipment keeps good technical status, delays the deterioration process, timely finds and eliminates the hidden trouble, and ensures the safe operation

What should be paid attention to in CNC machining aluminum parts

Pay attention to some details in CNC processing of aluminum parts can avoid quality problems of aluminum parts and improve the production efficiency of enterprises. What should we pay attention to before CNC processing?

CNC machining of aluminum shell

1. For the new die, the processing drawing should meet the requirements and the data should be clear; the processing drawing of the new mold should be signed by the supervisor, and all columns of the processing drawing have been filled in.

2. The workpiece has the qualification mark of quality department.

3. After receiving the program sheet, check whether the workpiece reference position is consistent with the drawing reference position.

4. Check every requirement on the procedure list and confirm whether the program is consistent with the requirements of the drawing. If there is any problem, you must work with the programmer and production team to solve the problem.

5. According to the material and size of the workpiece, judge the rationality of the selection of the tool for the program of roughening or smooth cutting. If the application of the tool is found to be unreasonable, the programmer should be informed immediately to make corresponding changes, so as to improve the processing efficiency and machining accuracy of the workpiece.

In the process of using CNC to process aluminum parts in normal production, the following contents should be paid attention to:

1. When the surplus on the top surface of the workpiece is too large, when using a large knife to manually remove the surplus, remember not to use the depth of the gong.

2. The most important machining tool is the first tool. If you operate and check carefully, you can know whether the tool length compensation, tool diameter compensation, program, speed, etc. are wrong, so as to avoid damaging the workpiece, cutter and machine tool.

3. Try the cutting procedure as follows:

a. The height of Di point is the highest elevation of 100 mm, and the eye is used to feel whether it is correct;

b. Control “fast move” to 25% and feed to 0%;

c. When the tool approaches (about 10 mm, machining surface), stop the machine;

d. Check whether the remaining stroke and program are correct;

e. After starting the machine again, put one hand on the pause button to stop the machine at any time, and the other hand controls the feed rate;

f. When the tool is very close to the workpiece surface, it can be stopped again, and the remaining stroke of Z axis must be checked.

g. After the machining and cutting is smooth and stable, adjust the control back to normal state.

4. After inputting the program name, use a pen to copy back the program name on the screen, and then check it with the procedure sheet. When opening the program, pay attention to check whether the tool path size in the program is consistent with the procedure sheet, and fill in the file name and cutter diameter size in the signature column of the process sheet immediately. It is forbidden to fill in the file name and cutter diameter size after or before the process.

5. In principle, NC technicians are not allowed to leave when the workpiece is rough. If it is necessary to leave due to tool change or assistance in adjusting other machine tools, please ask other NC team members or come back regularly for inspection.

6. When making the middle light, the NC technician should pay special attention to the place that is not opened during the roughening to prevent the cutter from hitting this area.

7. Program cutting. In case of interruption of the program during processing and it wastes too much time to start from the beginning, the team leader and the programmer shall be informed to modify the program and cut out the part that has been passed.

8. Program exception. In case of abnormal conditions of the program, and not sure, you can hang high to observe the process, and then decide the next action.

9. NC technicians can adjust the speed and speed provided by the programmer according to the actual situation. However, special attention should be paid to the fact that the speed of small pieces of copper can not be turned fast when it is exposed to rough, so as to avoid the loosening of workpieces due to oscillation.

10. During the process of workpiece processing, the NC technician should check with the spare parts drawing to see if there is any abnormal condition. Once the two do not match, they must stop the machine immediately and inform the team leader to check whether there is any error.

11. When using the tool with a length of more than 200 mm, it is necessary to pay attention to the allowance, feed depth, rotation speed, travel speed and other issues, so as to avoid tool swing. At the same time, the travel speed of the corner position should be controlled.

12. If the tool diameter is required to be detected on the program sheet, the operator must be responsible for it carefully, and record the diameter of the test. If it is beyond the tolerance range, it should be immediately reported to the team leader or tool change.

13. When the machine tool is in automatic operation or free, the operator should go to the workstation to understand the remaining processing programming, prepare and grind the appropriate tool for the next machining standby, so as to avoid shutdown.

14. Process error is the main reason for waste of time: wrong use of inappropriate tools, wrong processing sequence, waste of time in the position without processing or non computer processing, improper processing conditions (too slow speed, empty tool, too dense tool path, too slow feed, etc.), when the above events occur, it can be connected with programming, etc.

15. In the process of machining, we must pay attention to the wear condition of the cutting tool. We should change the cutter grain or the tool properly. After changing the cutter grain, we should pay attention to whether the contact boundary of the machining is consistent.

CNC machining technology of aluminum shell

With the progress of society, the development of science and technology, with the improvement of living standards, the quality of life has been greatly improved. Many people are thinking about how to improve the quality. The better the technology is, the more market demand will be, and the higher the efficiency will be. What are the CNC processing techniques of aluminum shell? Let’s have a look!

CNC machining of aluminum shell

1. Reasonable selection of cutting amount, the staff according to the need to be processed material, hardness, cutting state, material type, cutting depth and so on to choose the cutting speed. These conditions are the ideal conditions to effectively protect the machine from wear.

The three factors of cutting conditions: cutting speed, feed rate and cutting depth directly cause tool damage. With the increase of cutting speed, the tool tip temperature will rise, which will produce mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1 / 2

The relationship between feed condition and tool back wear occurs in a very small range. But the feed rate is large, the cutting temperature rises, and the back wear is large. It has less effect on the tool than the cutting speed. Although the influence of cutting depth on the tool is not as great as the cutting speed and feed rate, but when the cutting depth is small, the hardened layer of the material to be cut will also affect the tool life.

The user should select the cutting speed according to the material to be processed, hardness, cutting state, material type, feed rate, cutting depth, etc.

The selection of suitable processing conditions is based on these factors. Regular and stable wear is the ideal condition for service life.

2. Choose the right tool. For rough turning, generally speaking, it is better to choose high strength and durable cutting tools, which can better meet the requirements of rough turning.

How to select machining tool reasonably? How many factors are there in cutting parameters? How many kinds of tools are available? How to determine the tool speed, cutting speed, cutting width?

① No regrinding cemented carbide end milling cutter or end milling cutter should be used in plane milling. In general, the second tool path should be used as far as possible, and the end milling cutter can be used for rough milling, and the cutter can be continuously moved along the surface of the workpiece.

② End mills and end mills with cemented carbide inserts are mainly used for machining boss, groove and box face.

③ Ball cutter and round knife (also known as round nose knife) are commonly used to process curved surface and variable bevel profile. The ball cutter is mostly used for semi finishing and finishing.

3. Choose a reasonable fixture. Parts should fully meet the needs of the machine, in order to reduce unnecessary positioning error, good choice of special fixture clamping tools. Machining route refers to the motion track and direction of the cutter relative to the parts in the process of NC machine tool processing.

① The machining accuracy and surface roughness requirements shall be guaranteed;

② The processing route should be shortened as far as possible to reduce the tool idle travel time.

4. The working route of the front waist is determined. Shorten the machining route as far as possible to reduce the wear of the machine.

The technical requirement of CNC machining technology is that the control system can logically process the program with control code or other symbol instructions, and decode it by computer, so that the machine tool can move and process parts. The blank is processed into semi-finished products by cutting tool.