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

How to clamp the gauge standard parts

1: Clamping mode of horseshoe indenter: the material of the chuck is aluminum, and the opening should be greater than 6.5mm. This mode is usually used by people’s inspection tools. The three coordinate measuring machine can measure the base square of RPS positioning surface. In order to achieve this goal, the clamp arm should not exceed the base of RPS positioning surface, otherwise the three-dimensional probe will be blocked by the clamp arm and affect the measurement. In addition, if there is positioning or inspection pin on the positioning surface, it should be noted that the chuck should not interfere with the positioning or inspection pin to affect the maneuverability when the clamp is opened.

2: Positioning surface and clamping: in principle, each positioning surface shall be clamped locally. The clamping point shall be located at the base of the positioning surface, and the clamping target of the clamp of the gauge guideline piece shall be the same as the normal direction of the positioning surface. If the angle between the locating surface and the supporting surface of the clamp is less than 5 degrees, it can be ignored. If it is more than 5 degrees, the clamping target of the clamp and the normal direction of the locating surface should be the same.

3: Flat push type clamp: including clamp and tension spring clamp. In general, we should think about clamp.

Surface treatment technology of metal parts processing

Contact resistance heating and quenching: at the beginning and the end of the electrode, the voltage less than 5 V is applied to the workpiece, and a large amount of resistance heat flows through the contact between the electrode and the workpiece, so that the workpiece surface is heated to the quenching temperature, and then the electrode is removed, and the heat is transferred into the workpiece interior and the surface is cooled rapidly, that is to say, the quenching target is reached. When the long workpiece is processed, the electrode moves forward continuously, and the part left behind is hardened continuously. The advantages of this method are simple equipment, simple operation, easy automation, small distortion of the workpiece, no need for tempering, which can significantly improve the wear resistance and scratch resistance of the workpiece, but the hardening layer is relatively thin (0.15-0.35mm). The average of microstructure and hardness is poor. This method is mainly used for surface hardening of machine tool guide rail made of cast iron, and the use boundary is not wide.

Electrolytic heating and quenching: place the workpiece in the electrolyte of acid, alkali or salt water solution, connect the workpiece to the cathode, and connect the electrolytic cell to the anode. After the direct current is connected, the electrolyte is electrolyzed, oxygen is released on the anode, and hydrogen is released on the workpiece. Hydrogen around the workpiece causes gas film, which becomes a resistance body and generates heat. The surface of the workpiece is heated to the quenching temperature quickly, and then the power is cut off. The gas film dissipates immediately, and the electrolyte becomes the quenching medium, which makes the surface of the workpiece cool and harden rapidly. The commonly used electrolyte is an aqueous solution containing 5-18% sodium carbonate. The electrolytic heating method is simple, the processing time is short, the heating time is only 5-10 seconds, the production rate is high, the quenching distortion is small, it is suitable for a large number of small parts, and it has been used for the surface quenching of the exhaust valve rod end of the engine.

Laser heat treatment: the use of laser in heat treatment began at the beginning of the 70’s, and then entered the stage of production and use from the stage of laboratory discussion. When the laser with high energy density (106 w / cm2) is focused on the metal surface, the metal surface rises to the quenching temperature in a few percent seconds or even a few thousandths of a second. Due to the unique fast temperature rise of the mapping point, the heat is not enough to transmit to the surrounding metal, so when the laser mapping is stopped, the metal around the mapping point will play the role of quenching medium and absorb a large amount of heat, so that the mapping point will be cooled rapidly, and get very fine structure, with high mechanical function. If the heating temperature is high enough to melt the metal surface, a smooth surface may be obtained after cooling. This operation is called polishing. Laser heating can also be used for one-sided alloying, that is to say, plating a layer of wear-resistant or heat-resistant metal on the parts that are easy to wear or need heat resistance, or coating a layer of coating containing wear-resistant or heat-resistant metal, and then using laser mapping to make it melt rapidly, resulting in wear-resistant or heat-resistant alloy layer. A layer of chromium is first plated on the heat-resistant parts, and then the laser is used to melt it quickly, resulting in a hard tempering resistant chromium containing heat-resistant surface layer, which may greatly increase the service life and heat resistance of the workpiece.

Electron beam heat treatment: the beginning of the 70’s research and use. In the early stage, it is used for continuous annealing of thin steel strip and steel wire, with energy density up to 108W / cm2. Electron beam surface quenching should be carried out in vacuum, and other characteristics are the same as laser. When the electron beam bombards the metal surface, the bombardment point is heated rapidly. The depth of the electron beam through the raw material depends on the accelerating voltage and the density of the raw material. For example, a 150 kilowatt electron beam has a critical penetration depth of 0.076 mm on the iron surface and 0.16 mm on the aluminum surface. The electron beam bombards the surface in a short time, the surface temperature rises rapidly, while the substrate remains cold. When the electron beam stops bombarding, the heat transfers rapidly to the cold base metal, which makes the heated surface self quench. In order to effectively carry out “self cooling quenching”, a ratio of 5:1 should be maintained between the volume of all workpieces and the volume of quenching surface. The surface temperature and quenching depth are also related to the bombardment time. The heating speed of electron beam heat treatment is fast, and the time of austenitizing is only a few seconds or even shorter. Therefore, the surface grain of workpiece is very fine, the hardness is higher than that of normal heat treatment, and it has excellent mechanical function.

Steps and advantages of CNC processing samples

There are several processes for sample: CNC processing samples, 3D printing samples, silica gel replica samples, sheet metal samples, low-pressure injection samples, etc.Let’s briefly describe the pace and advantages of CNC processing samples.

Many people also call it the first mold for sample. Generally speaking, after an industrial product is designed, it is not put into manufacturing as soon as possible, but should first manufacture a small number of sample according to the drawings. The goal is to see the samples of the shaped products in advance. If not, then modify the drawings until there is no objection, and then start batch manufacturing. This small mold is the sample in the mouth.

The steps of CNC processing sample as follows:

1) Discuss the CNC processing value and delivery date, and sign the processing agreement.

2) Analyze the part drawing and product configuration drawing, and analyze the process of the part.

3) Select the blank.

4) CNC sample programming.

5) Confirm the machining allowance of each process, calculate the process size and yamen service.

6) Confirm the equipment and tools, clamps, measuring tools and auxiliary equipment used in each process.

7) Confirm the cutting amount and working time quota.

8) Confirm the technical requirements and inspection methods of each key process.

9) Fill in the process documents of CNC machining sample proofing.

CNC processing sample has the following advantages:

① Complex tooling is not required. If we want to change the form and size of the parts, we only need to modify the processing program of the parts, which can be used in the development and modification of new products.

② The processing quality of sijunda sample is stable, the processing precision is high, the repeated precision is high, and it is suitable for the processing requirements of high-precision products.

③ Under the condition of batch manufacturing, the manufacturing efficiency is higher, which can reduce the time of manufacturing planning, machine adjustment and process inspection.

④ It can be used to process complex surfaces which are difficult to be processed in conventional way, and even to process some processing parts which cannot be observed

Surface treatment technology of precision parts

In the essential work, the requirements for strength and toughness are relatively high. Its working function and service life are greatly related to its surface function. However, the improvement of surface function can not be achieved purely by relying on raw materials, and it is often uneconomical to do right and wrong. However, in the essential processing, its function must reach the criterion. At this time, surface processing technology is needed, which often can In recent years, the technology has also developed rapidly. In the mold surface treatment limit mold polishing technology right and wrong often important link, is also an important process in the workpiece processing process. The surface treatment process of careful parts is often important in the process of machining, so what are the surface treatment processes of careful parts?

It is worth mentioning that the polishing of the die surface of the careful parts is not only influenced by the process and polishing equipment, but also by the specularity of the raw materials of the parts, which has not been paid enough attention to in the current processing, which is also the footnotes, and the polishing itself is affected by the raw materials. Although the processing technology to improve the surface function of the well-rounded parts has been constantly upgraded, the most used in the processing of the well-rounded parts is still focused on the hard precipitation, nitriding and carburizing technology.

Because the nitriding technology can achieve a high level of surface function, and the nitriding technology has a high concordance with the quenching technology of the steel in the well-rounded parts, and the nitriding temperature is often low, so after the nitriding technology is processed, there is no need for intense cooling process, so the deformation of the well-rounded parts will be quite small, so the nitriding technology is also It is one of the earliest techniques used to strengthen the surface function during the careful processing of parts and components, and it is also the most common one currently used.

The above is the introduction of “surface treatment process of careful parts”, I hope to bring you positive assistance

What is the processing technology of aluminum parts in surface grinder

When grinding aluminum parts, the grinding wheel is waxed. Before grinding aluminum parts, open the grinding wheel cover and shovel the ash inside, so as to prevent the ash inside the grinding wheel cover from falling off on the parts in the process of grinding aluminum parts. There will be deep marks on the parts after the grinding wheel is rolled. The grinding wheel should not be too thick or too thin. It is better to grind it with a heat-treated material for a while, blunt the grinding wheel a little bit, and then back and forth Block against the part, use water-soluble cutting fluid to play a layer on the surface of the part, while grinding, according to the thickness of the aluminum part, choose how much to cut, generally 0.01 for the large aluminum plate, the key depends on your own technology, I am grinding aluminum plate 6.50 now 0.05 * 300 * 580 plate, grinding thickness parallelism 005, 0.08 under one knife, grinding aluminum plate is easy to deform and stick grinding wheel, peers who just contact with grinding aluminum plate should feed less and turn over more,

The function of precision machining technology

1、 It is the main technical document to guide production

The production planning and scheduling of machining workshop, the operation of workers, the processing quality inspection of parts, and the accounting of processing cost are all based on the process specification. In dealing with the problems in production, the technological procedure is often taken as the common basis. In case of handling quality accidents, the responsibilities of relevant units and personnel shall be determined according to the process procedures.

2、 Is the main basis of production preparation

When the workshop wants to produce new parts, it should first formulate the machining process specification of the parts, and then prepare for production according to the process specification. For example, the analysis and research of key processes in the processing technology of new parts, the preparation of necessary knives, clamps and measuring tools, the purchase or manufacturing of raw materials and blanks, the purchase of new equipment or the modification of old equipment, etc. must be carried out according to the technology.

3、 It is the basic technical document of the new machinery manufacturing plant

When a new batch or large-scale machining workshop is built, the type and quantity of the machine tools required and the layout in the workshop shall be determined according to the process specification, and then the size of the workshop area, the configuration of power and hoisting equipment, and the type of work, technical level and quantity of the workers required shall be determined.

What is the principle of precision parts processing

The basic research focuses on how to reduce the deviation and improve the accuracy. Therefore, the basic principles for selecting the natural surface are as follows:

1: Principle of datum coincidence. The design datum as far as possible shall be selected as the positioning datum. Uniqueness is at the end of the final, to ensure accuracy, we should pay more attention to this principle. In this way, it is advisable to prevent the formation of position deviation datum deviation;

2: The principle of datum unification. It is necessary to select a unified surface treatment for positioning datum plane, although the position accuracy between the surfaces shall be ensured, and the processing shall be repeated occasionally according to the principle of common datum;

3: The principle of self reference. Some small machining allowance and unified finishing process ensure machining quality and production rate, as a basic level with carefully machined surface itself.

That’s all. We’re looking forward to seeing you next time. We’ll pay attention to safety in haze weather.

Principle of vacuum suction for CNC machining die

Generally speaking, swindling vacuum sucker to grab the finished product is the cheapest way. There are various types of vacuum suction cups. The rubber suction cups can be operated under high temperature. The silicon rubber suction cups are quite suitable for catching the rough finished products. The polyurethane suction cups are very durable. In addition, in essence, if the sucker is required to have oil resistance, it is advisable to study the use of polyurethane, nitrile rubber or vinyl containing polymers and other raw materials to manufacture the sucker. Generally, in order to prevent the surface of the finished product from being scratched, it is better to choose the suction cup with wave tube made of NBR or silicone rubber as the raw material, which is made of NBR and has great breaking force, so it is commonly used in various vacuum holding equipment.

2、 The vacuum sucker used on the CNC computer gong is the foot color of the fixture beside the CNC machining center. Some workpieces require high surface smoothness, so the fixture of the commonly used CNC computer gong cannot be used. At this time, the vacuum sucker can be used. But we seldom use the vacuum sucker made of rubber near the CNC computer gongs, but more use the CNC vacuum sucker. The so-called CNC vacuum sucker is a kind of unique vacuum sucker that uses a vacuum generator plus a switch. The principle of drawing is the same as that of rubber vacuum sucker. They all create a vacuum environment to make the atmospheric pressure press the sucker on the workpiece, but the CNC vacuum sucker The vacuum of is produced by the vacuum generator in the vacuum environment, and there is a big difference in the appearance. The rubber vacuum sucker is a simple vacuum element, while the CNC vacuum sucker is the same as a big plate. The use of vacuum sucker in CNC computer gongs is usually due to the fact that the workpieces processed have high requirements for surface smoothness. Maybe it is only used when the fixture of CNC computer gongs cannot clamp the workpieces very well. It is a unique and cheap fixture in CNC machine tools.

Gantry CNC for gantry milling

This type of cutting machine is of gantry structure, with a transverse span of 3M, 4m, 5m, 6m, 8m and other specifications. It is driven bilaterally with stable operation, good configuration and high working efficiency. It can be used for cutting large, medium and small steel plates of various carbon steel, manganese steel, stainless steel and other metal raw materials. According to the user’s requirements, more cutting torches can be configured, or a dual-purpose cutting method of special-shaped cutting and straight cutting can be configured, in addition, an automatic capacitance or plasma heightening system can be selected.

System characteristics

1. The system has improved performance, high stability, strong anti-interference, and is applicable to all kinds of plasma power sources outside China;

2. Highlight the value advantage and have a strong price ratio

The difference between fixture two color mold and rubber covered mold

A. Two color mold: two kinds of plastic raw materials are injected into the same injection molding machine in two times, but the products are only produced once. Usually this kind of molding process is also called double material injection molding. It is usually completed by a set of molds, and special two-color injection molding machine is required. Weixun two-color mold B. rubber covered mold (secondary molding): two kinds of plastic raw materials are not sure to be injected on the same injection molding machine, which are divided into two times of molding; the products are taken out of one set of mold, and then put into another set of mold for the second injection molding. Therefore, usually this kind of molding process is usually completed by two sets of molds, without the need for special two-color injection molding machine. Overview of two-color mold and rubber covered mold: in the design of rubber covered mold, attention should be paid to the positioning of hard rubber parts. It is necessary to achieve * sealing and have anti slope holes on the rubber parts, so as to prevent rubber deformation. At present, the two-color mold is increasingly popular in the market. In this process, it is better to make the appearance of the product more beautiful, easy to change color and not spray, but the cost is high and the technical requirements are high

1. The two forms of cavity are different. Farewell forms a product. The two forms of core are exactly the same. 2. After the front and back dies of the die rotate 180 o in the center, they must be consistent. Make sure to do this test when designing. 3. Pay attention to the position of the top pinhole with a minimum interval of 210mm. For large moulds, the number of holes in the ejector pin shall be increased appropriately. Moreover, since the ejector attached to the injection molding machine itself can not be long, we must design a long ejector in our mold, and the ejector will grow 150 mm out of the mold base plate for control. Two locating rings must be designed on the back mold bottom plate. 4. The total thickness of front formwork panel plus a plate shall not be less than 170mm. Please carefully check other reference data of this type of injection molding machine, such as the maximum mold thickness, the minimum mold thickness, the spacing of the top stick hole, etc. 5. It is better to design the nozzle of the three plate mold as the automatic demoulding behavior. Special attention should be paid to the demoulding behavior of the soft rubber nozzle. 6. The depth of sprue at the front side shall not exceed 65mm. The distance between the top of sprue on the upper side (large water port) and the center of mold embryo shall not be less than 150 mm. 7. In the design of the second injection molding of the cavity, in order to prevent the insertion (or rubbing) of the cavity from damaging the product glue position which is still well formed for the first time, it is advisable to design a part of the cavity avoidance. However, we must carefully study the strength of each sealing position, i.e. in injection molding, is there any possibility of plastic deformation under large injection pressure, resulting in the possibility of batch front in the second injection molding? 8. During injection molding, the product size of the first injection molding may be slightly larger, so that it can be pressed more tightly with another cavity during the second molding to achieve the sealing effect. 9. Pay attention to whether the flow of plastic in the second injection will impulse the products still forming for the first time and make their glue position deformed? If this is possible, we must think of ways to improve. 10. Before closing the A and B plates, pay attention to whether the front mold slider or lifter will reset first and crush the product? In this way, we must find a way to close the die on board a and B first, and then the slider or life of the front die can be reset. 11. although the water transportation deployment of the two CAVITY and CORE is sufficient, they are balanced and the same. In 12.99% of cases, the hard part of the product is injected first, and then the soft part of the product is injected. Because soft rubber is easy to deform.