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How to Use CNC Tools to Save Costs Efficiently

Rake angle of numerical control tool

Generally speaking, the rake angle has a great influence on cutting force, chip discharge and tool durability.

The influence of rake angle of NC tool

1) Large positive front angle and sharp cutting edge;

2) The cutting power decreases by 1% with the increase of front angle by 1 degree.

3) If the positive rake angle is too large, the edge strength decreases; if the negative rake angle is too large, the cutting force increases.

Large negative rake angle of NC cutter

1) Cutting hard materials;

2) The cutting edge should be strong enough to adapt to the intermittent cutting and the processing conditions of cutting the surface layer containing black skin.

Large positive front angle for

1) Cutting soft materials;

2) Free cutting materials;

3) When the rigidity of machined materials and machine tools is poor.

Benefits of rake angle cutting with NC tools

1) Because the front angle can reduce the resistance encountered in cutting, the cutting efficiency can be improved.

2) It can reduce the temperature and vibration generated during cutting and improve the cutting accuracy.

3) Reduce tool wear and prolong tool life;

4) When choosing the right cutting tool material and cutting angle, the use of rake angle can reduce tool wear and enhance the reliability of the cutting edge.

Excessive front corner

1) Because the increase of the rake angle will reduce the angle and cutting efficiency of the cutting tool to cut into the workpiece, if the rake angle is too large, the tool will easily wear and even collapse when cutting the workpiece with higher hardness.

2) When the material of the cutting tool is weak, the reliability of the cutting edge can hardly be maintained.

CNC Tool Back Angle You, CNC Machining

The rear angle reduces friction between the back of the cutter and the workpiece, and enables the cutter to cut into the workpiece freely.

Effect of Back Angle of NC Tool

1) Large rear angle, small positive wear of the rear knife

2) The strength of the tool tip decreases when the rear angle is large.

Small rear angle for

1) Cutting hardness material;

2) When cutting strength is high.

Large rear angle for

1) Cutting soft materials

2) Cutting materials that are easy to work and harden.

Benefits of Back Angle Cutting

1) Large rear angle cutting can reduce the wear of the flank, so it is better to prolong the life of the tool when the front angle loss does not increase sharply.

2) Generally speaking, it is easier to dissolve in cutting ductile and softer materials. Solution can increase the back angle and the contact surface of the workpiece, increase the cutting resistance and reduce the cutting accuracy. Therefore, if such materials are cut with a larger rear angle, the occurrence of this situation can be avoided.

Limitation of Back Angle Cutting of NC Tools

1) When cutting materials with low heat transfer, such as titanium alloy and stainless steel, the use of large rear angle cutting will make the rake face prone to wear, and even tool damage. Therefore, large rear angle is not suitable for cutting this type of material.

2) Although the use of large rear angle can reduce the wear of the flank, it will accelerate the decay of the blade. Therefore, the cutting depth will be reduced and the cutting accuracy will be affected. For this reason, technicians need to adjust the angle of the tool regularly to maintain the cutting accuracy.

3) When cutting materials with high hardness, if the large rear angle is too large, the resistance encountered in cutting will cause the front angle to be damaged or damaged due to the strong compressive force.

Which kind of vibration screen spring has good shock absorption effect

1. Maintenance and service life

Air springs need almost no daily maintenance, and can be regularly dedusted, because each spring with a pressure meter and a level control unit can easily see its working state, pressure regulation is also very important, just press the button with your finger, the service life is generally more than 30 years.

The steel spring can not detect its working status, only after the damage can be found, such as during the use of the test, it is simply impossible. With the increase of self-stress, the stress difference of each spring becomes larger and larger, and its service life generally does not exceed 15 years.

2. Isolation efficiency and range

Vibration isolation efficiency refers to the amount of vibration that isolation system can isolate when a fixed excitation frequency occurs. Vibration isolation range refers to the frequency range in which the vibration isolation system can effectively isolate vibration. The isolation efficiency and range are related to the resonant frequency of the isolator. The lower the resonant frequency of the isolator, the higher the isolation efficiency and the larger the isolation range.

The calculation shows that for the same excitation frequency of 10Hz, the isolation efficiency of steel spring is about 80%, while that of air spring is 98%, that is to say, 98% of the vibration is isolated. Of course, the smaller the excitation frequency, the more obvious the advantages of air spring relative to steel spring in vibration isolation efficiency.

For air spring, as long as the vibration frequency is higher than 0.85Hz, effective vibration isolation will be produced. For steel spring, vibration isolation can be achieved only when the excitation frequency is higher than 4Hz. That is to say, the steel spring has no vibration isolation effect between 0.85Hz and 4Hz, while the air spring can effectively isolate vibration. Moreover, the isolation efficiency of air spring is always higher than that of steel spring no matter how large the excitation frequency is.

3. Horizontal Regulation of Vibration Isolation System

The mass block of the vibration isolation system is suspended. After the initial horizontal calibration of the test platform, it can not guarantee that the test platform will always be horizontal in the future.

If the steel spring isolator is used, after the position, weight and center of gravity of the test machine or sample are changed (such as changing the test sample, replacing the transmission with the axle, or adding a sample of the transmission), the horizontal degree of the test platform will change, and the stress of several steel springs in different positions will be uneven. First of all, we need to solve the level problem, manually install gaskets, apply jacks and other facilities, no position sensors, using a level ruler to verify the level of the test platform, time-consuming and laborious. After solving the horizontal problem, the second problem can not be solved, that is, the force of each spring is not uniform. The different deformation of each spring results in the difference of its internal stress. The performance of each spring will be different, and the isolation efficiency and service life will be greatly affected.

The vibration isolation system of air spring perfectly solves the problem of horizontal adjustment of the test platform. Each air spring vibration isolation system is equipped with an automatic horizontal control unit. Applying the principle of three-point leveling, all air springs are divided into three groups, each group is controlled by an air pressure control valve group. Each group of air springs has a position sensor, which can automatically adjust the air pressure to achieve the purpose of adjusting the level of the test platform.

After changing the position, weight and center of gravity of the test machine or sample (such as replacing the test sample, replacing the transmission with the axle, or adding a sample of the transmission), the level of the test platform will change, and the automatic horizontal control unit of the air spring vibration isolation system will begin to function, and the level of the test platform will be automatically adjusted by a small amount of air charging and discharging. With very small difference in the height of each air spring, the pressure is not the solid part of the air spring itself, but the compressed air, which has no effect on the air spring itself.

How to make the cutting plan of metal parts

When manufacturing parts on CNC machine tools, there are generally two kinds of situations. The first one is that there are parts drawings and blanks. The CNC machine tools suitable for the parts should be selected. The second situation: there is already a CNC machine tool, to choose parts suitable for the machine tool. In either case, the main factors to be considered are the material and type of the blank, the complexity of the part contour, size, accuracy, number of parts, heat treatment requirements and so on. Following is a brief introduction of how to choose the manufacturing process of parts in Yida Borun Petrochemical Company.

1. Steps for developing part technology

(1) Determining the type of blank

The type of blank shall be determined according to the material, shape and size of the part and the number of workpieces placed.

(2) Procedures for determining parts

The process of parts shall be determined according to all technical requirements such as dimensional accuracy, surface roughness and heat treatment, as well as the type, structure and size of blanks.

(3) Determining the manufacturing process

That is to determine the machine tool, workpiece clamping method, processing method, measurement method and processing size (including the processing allowance for the next process).

II. Principles for Formulating Parts Processing

(1) Precision base plane principle

The part must choose the suitable surface as the base surface of the machine tool or fixture. As the first process to locate the base surface, the rough surface is called the rough base surface, and the processed surface is called the fine base surface. The main base surface should be processed first.

(2) The principle of separation of roughness and precision

For the surface with high precision, it is generally necessary to finish the workpiece after all rough processing. In this way, the deformation of workpiece caused by clamping force, cutting heat and internal stress during rough machining can be eliminated, and the arrangement of heat treatment process can be facilitated. In mass production, rough and finish processing are often carried out on different machine tools, which is also conducive to the rational use of high-precision machine tools.

(3) One-time clamping principle

In the production of single piece and small batch, the surface with position accuracy requirement should be finished in one clamp as far as possible.

3. Programmes to Improve Cutting Efficiency

(1) High Speed Cutting

Milling is the main technology of high-speed cutting, and milling cutter is the main tool of high-speed cutting. This kind of tool bears a great centrifugal force when it rotates at high speed. Because its function far exceeds that of cutting force, it becomes the main load of the tool. At very high speed, besides the balance of the tool and fixture itself is the necessary prerequisite, the overall balance of the tool after installation is still needed.

(2) High feed cutting

In the traditional way of finishing, because there are certain requirements for the surface roughness of the workpiece, the feed of the tool is small. In theory, the surface roughness of the workpiece is only affected by the grain size of the workpiece material as long as the feed rate does not exceed the width of the tool’s polishing edge without considering the stiffness and the micro-defects of the polishing edge itself.

(3) Large margin cutting

Large margin cutting is generally called heavy cutting, and large margin cutting is also one aspect of high efficiency cutting. By using impact-resistant and high wear-resistant heavy cutting milling cutters, the parts of the original process that need multiple cutting can be completed at one time, but because of poor accuracy, they are usually only used for rough work.

Selection of High Speed Cutting Oils

(1) Non-ferrous metal cutting oil

Cutting force and temperature are not high when cutting copper, aluminium alloy and non-ferrous and light metals. Special cutting oil for copper and aluminium alloy, which has good corrosion resistance and low proportion of anti-wear agent, can be selected.

(2) Cast iron cutting oil

It is necessary to select cutting oil with strong rust-proof function when processing cast iron. When cast iron and bronze are brittle materials, crushing chips often form in cutting, which easily flow with cutting oil everywhere and cause parts damage between machine tool guideways. Cutting oil with good cooling and cleaning performance can be used and filtering work can be done well.

(3) Alloy steel cutting oil

When cutting alloy steel and titanium alloy, if the cutting quantity is low and the surface roughness requirement is small, such as broaching and thread cutting, the cutting oil with excellent extreme pressure performance is needed, sulfurized fatty acid ester can be chosen as the main additive of extreme pressure cutting oil.

Do you know the future development of e-commerce and logistics

The development of cross-border e-commerce has led to the development of cross-border e-commerce logistics, but there are still a series of problems that can not be ignored, such as logistics timeliness, logistics cost, logistics system and so on, which have become the constraints of its development.

With the development of e-commerce, consumers’living and consumption habits have changed greatly. With the increase of shopping channels, consumers’ consumption habits have gradually changed from the previous price demand to the quality demand. The proportion of enjoyable and spiritual consumers is gradually increasing.

At present, the shopping modes of imported cross-border e-commerce mainly include the following:

(1) Platform e-commerce using direct mail and spelling for shipment

(2) Platform e-commerce using bonded warehouse or direct mail for delivery

(3) Self-operated e-commerce using bonded warehouse or direct mail delivery

(4) Using bonded warehouse or direct mail delivery platform + self-operated e-commerce:

With the development of economic globalization, trade and commerce between countries become more frequent. Exporting superior products overseas and importing needed products have become an important measure to promote the economic and social development of countries in the world. The emergence of the Internet has brought tremendous changes to the global economic development. More and more producers can realize the “disintermediation” development through the Internet. The use of the Internet can reduce the number of nodes in the circulation link, so as to achieve point-to-point product direct access. With China’s economic development entering a new normal era, cross-border e-commerce logistics, as a new bright spot of national economic growth, has attracted the attention of the state and the business community.

Innovative Development Direction of Cross-border E-commerce Logistics Business Model

Cross-border e-commerce logistics and cross-border e-commerce coordinated development. E-commerce and logistics are symbiotic. In recent years, the development of domestic e-commerce has driven domestic logistics industry to become a new hot industry, which is a good illustration of this point.

Therefore, the development of cross-border e-commerce will inevitably stimulate and drive the rise of cross-border logistics. The coordinated development of cross-border e-commerce and logistics industry can be achieved through resource and technology sharing and strategic coordination. It is cross-border logistics that promotes its own growth through the development of e-commerce, such as the development of mobile technology and the popularization of network, which has a great impact on cross-border e-commerce and logistics. Cross-border logistics should conform to the development momentum of e-commerce so as to become an important link in the development process of cross-border e-commerce.

Cross-border e-commerce and logistics can first find the initial source of their supply, especially in warehouse preservation, packaging, transportation and other aspects, strengthen cooperation, while promoting and meeting e-commerce needs, reduce logistics costs, reduce logistics time, reduce goods losses, and achieve coordinated development.

Sharing of multiple logistics modes

It embodies the effect of polymerization. Cross-border logistics includes international logistics, domestic logistics and so on. It involves entry-exit customs and commodity inspection. The logistics time is longer, the distance is farther and the way is more complex. Cross-border e-commerce is facing the global market, both sides of the transaction have certain differences in the level of logistics and commodity categories, so the requirements of logistics will be quite different.

Domestic logistics companies need to give full play to their strengths in Transnational E-commerce logistics, explore the types of E-commerce markets and the products they sell, and take the products with advantages as a breakthrough point to adapt to overseas markets step by step.

How to make the cutting plan of metal parts

(1) Determining the type of blank

The type of blank shall be determined according to the material, shape and size of the part and the number of workpieces placed.

(2) Procedures for determining parts

The process of parts shall be determined according to all technical requirements such as dimensional accuracy, surface roughness and heat treatment, as well as the type, structure and size of blanks.

(3) Determining the manufacturing process

That is to determine the machine tool, workpiece clamping method, processing method, measurement method and processing size (including the processing allowance for the next process).

II. Principles for Formulating Parts Processing

(1) Precision base plane principle

(2) The principle of separation of roughness and precision

(3) One-time clamping principle

In the production of single piece and small batch, the surface with position accuracy requirement should be finished in one clamp as far as possible.

3. Programmes to Improve Cutting Efficiency

(1) High Speed Cutting

(2) High feed cutting

(3) Large margin cutting

Selection of High Speed Cutting Oils

(1) Non-ferrous metal cutting oil

(2) Cast iron cutting oil

(3) Alloy steel cutting oil

The above is a common classification method of cutting technology. In actual cutting, it is necessary to constantly combine various factors such as workpiece, working condition, cutting tool, equipment and so on to analyze and optimize comprehensively, in order to get a suitable process with stable quality, economy and high efficiency.

What are the common surface treatment processes for stainless steel

There are many kinds of surface treatment processes for stainless steel, such as electroplating, anodic oxidation, sandblasting, painting, passivation, pickling, degreasing, rust removal and so on. This paper mainly introduces three common surface treatment processes of stainless steel, including passivation, pickling and degreasing, for the reference of friends in need:

1. Stainless steel passivation

The recommended surface for this process must be iron-free. The presence of stainless steel particles on the surface of any iron, cast iron, low carbon steel, medium carbon steel or low alloy steel will promote pitting corrosion of “free” iron and stainless steel on its surface. This is a very serious problem, so passivation is only used to treat stainless steel and stainless steel. The main purpose of stainless steel passivation is to prevent stainless steel surface oxidation and corrosion.

2. Stainless steel pickling

The purpose of stainless steel pickling treatment is to remove oxide scales on the surface of stainless steel after high temperature welding, heat treatment or hot working. At the same time, it can eliminate the contamination of steel or iron or steel particles which are corroded by red rust. Please note that if there is no acid solution to clean the surface after pickling, the surface will start to rust and corrode soon. The corrosion resistance of the steel surface layer below is reduced.

Stainless steel pickling process can be applied to all 200, 300, 400 series of stainless steel surface treatment. All pickling operations result in the removal of impurities on the metal surface with a slight change in size, so the result is that to some extent an extinction of visual brightness may also be a significant reduction in size.

Heat treatment in vacuum or a good controlled atmosphere, such as bright annealing, eliminates the need for pickling, and usually gives stainless steel a better finish.

3. Degreasing and degreasing of stainless steel cleaning agent

The pretreatment of any process of stainless steel surface treatment must first remove grease, cutting fluid, paint compounds and other lubricants, etc. before the surface heat treatment of stainless steel parts or the final passivation treatment can be carried out. Stainless steel parts must also be further welded before degreasing to prevent pickup carbon at high temperatures.

Usually, stainless steel cleaning agent is chosen. It only needs 1-8 minutes to soak at room temperature to remove any oil pollution. It is easy to operate and has low labor intensity. It can be reused repeatedly and effectively reduce the cost of production. In cleaning operations with other metals, the cleanliness rate can be increased through the use of brushing, spraying or stirring operations.

Points for Attention in Application of Waterborne Metal Paint for Vehicles

With the increasingly stringent environmental laws and regulations, water-based paint is also an inevitable choice for the application of automotive painting. We all know that automotive paint is more extensive: water-based anti-rust paint, water-based anti-corrosion paint, water-based glass paint, water-based plastic paint, water-based decorative paint, etc.

Waterborne metal paint has been widely used in the field of automobiles for several years, but most domestic waterborne paint manufacturers let downstream enterprises change their original painting equipment and processes to use their waterborne paint, and even some waterborne paint manufacturers invest to help them change their equipment. In fact, it is increasing costs and wasting resources. According to Xiaobian, at present, only a few domestic waterborne paint manufacturers with relatively senior qualifications are in the market. Using the existing painting equipment and technology of enterprises, we can directly apply water-based paint, such as industry benchmark infinite flower paint. Since 1998, we have been focusing on the research and development of water-based paint.

Liu Gong, Ministry of Infinite Flower Water Paint Transportation Metallic Paint Project, said that while attention should be paid to the operating characteristics of such equipment as paint mixing system, automatic spraying system, coating flash drying system and environmental temperature and humidity control system in spraying room, attention should also be paid to the surface roughness of electrophoretic coatings and the paint of solvent-based varnish (single component or double component) in the implementation of intermediate-free coating process. Film thickness and appearance fullness.

At present, the focus of development of infinite flower waterborne metal paint is to expand the temperature and humidity range of its construction environment as far as possible, promote the localization of key raw materials, and further reduce the material cost of waterborne metal paint.

Engine, transmission, axle and other power assembly parts, as well as chassis parts of locomotive represented by leaf spring, transmission shaft and shock absorber, most of these locomotive parts adopt low temperature (about 80 C) drying coating due to the particularity of the products (large thermal capacity, rubber and plastic parts or grease). Based on the requirement of environmental protection, more and more locomotive parts coating lines using solvent-based anticorrosive paint are gradually replacing with water-based anticorrosive paint.

Waterborne anti-rust and anti-fouling paint requires high cleanliness of workpiece surface, a little rust is not a problem, but there must be no oil stain, so the pretreatment requirements are strict, Infinite Flowers in view of this difficulty, introduced in 2007 and environmental protection and direct contact with the skin, better use of water-based rust remover and water-based oil remover, we collectively called surface treatment fluid.

The construction environment of waterborne anticorrosive paint is not particularly strict with temperature and humidity requirements, but too much humidity can easily cause problems such as film hanging, poor dryness and blistering. Generally, it can be solved by strengthening ventilation and setting low temperature gradient baking. In order to realize the “thick coating” of waterborne anticorrosive paint on locomotive parts, high-pressure airless spraying is also recommended for waterborne paint before spraying and under the technical communication with the manufacturer, whether water is added and diluted or not.

With the increasing attention paid by the state to the clean production of automobiles, Infinite Flower Paint vigorously promotes the development and application of water-based paints for automobiles such as metals, glass and plastics in China. Infinite Flower appeals for the cooperation of paint enterprises, painting equipment enterprises, research institutes and automobile enterprises to jointly tackle key problems and strive to launch a series of water-based coatings for locomotives with high cost performance and good applicability for painting. And realize industrialized intelligent application.

Maintenance Scheme of Water Pump

During the long-term operation of water pumps, wear of bearing chamber, bearing position, crack rupture of pump body, cavitation and erosion of water pumps often occur. After the above problems occur, the traditional solution of enterprises is repairing or repairing after brush plating, but both of them have some drawbacks: the thermal stress caused by high temperature of repairing welding can not be completely eliminated, which can easily cause material damage and lead to bending or fracture of parts; while brush plating is limited by the thickness of coating, easy to peel off, and the above two methods are repairing metal with metal, which can not change the “hard”. For the “hard” coordination relationship, under the combined action of various forces, it will still cause re-wear. In contemporary western countries, polymer composites are mostly used to repair the above problems. They have super adhesion, excellent compressive strength and other comprehensive properties. It can be repaired with high polymer materials without disassembly and machining. There is no effect of repair welding thermal stress and repair thickness is not limited. At the same time, the metal material of the product does not have the retreat ability, which can absorb the shock and vibration of the equipment, avoid the possibility of re-wear, and greatly prolong the service life of equipment components, save a lot of downtime for enterprises, and create huge economic value.

Static Balance of Impeller

When the pump rotor works at high speed, if its mass is not balanced, a large centrifugal force will be generated when it rotates, which will cause vibration or damage of the pump. The balance of the rotor is achieved by the mass balance of its components (including shaft, impeller, sleeve, balance disk, etc.). Therefore, the static balance check of the newly installed impeller should be carried out. Specific methods are:

(1) Install the impeller on the false axle and place it on the static balance test bench with the adjusted level. There are two tracks on the test bench, on which the false axle can roll freely.

(2) Mark on the heavier side of the impeller. If the impeller mass is unbalanced, the heavier side will always automatically turn below. In the symmetrical position (i.e. the lighter side) where the emphasis is placed, add heavy blocks (using surface sticking or clamping to increase or decrease iron sheets) until the impeller can stop at any position.

(3) weigh the weight of the weighting block. The balance of the impeller is achieved by reducing the weight on the heavier side rather than on the lighter side of the impeller. When reducing weight, milling machine or grinding wheel can be used (when removal is not large), but attention should be paid to the depth of milling or grinding should not exceed 1/3 of the thickness of impeller cover plate. After static balancing, the allowable deviation of static balancing should not exceed the product of outer diameter of impeller and 0.025 g/mm. For example, an impeller with a diameter of 200 mm has an allowable deviation of 5 g.

Dismantling and assembling of coupling

(1) When removing the coupling, the copper rod should be padded instead of hammer, and the hub of the coupling should be hit instead of the outer edge of the coupling, because it is very easy to be damaged here. The best way is to dismantle the coupling with a captive. For small and medium-sized pumps, the coupling is easy to take down because of its small interference. For larger pumps, the coupling and shaft fit have larger interference, so the coupling must be heated when disassembled. (2) When assembling coupling, attention should be paid to the serial number of key (for coupling with more than two keys). When striking with a copper rod, attention must be paid to the striking part. For example, when tapping the end face of the shaft hole, it is easy to cause the shaft hole to shrink, so that the shaft can not pass through; when tapping the outer edge of the wheel, it is easy to destroy the flatness of the end face, which will affect the accuracy of the measurement in the future when the plunger is used to align. For the coupling with larger interference, it should be heated and installed again.

(3) The pins, nuts, washers and rubber pads of the coupling must be kept in accordance with their specifications and sizes so as to avoid affecting the dynamic balance of the coupling. Corresponding markings should be made on the coupling bolts and the corresponding coupling pin holes in order to prevent misalignment.

(4) Transitional fit is generally used for coupling and shaft. There may be a small amount of interference or a small amount of clearance. Looser transition fit can be used for coupling with longer hub. Because of its long shaft hole and rough surface processing, some interference will occur naturally after assembly. If it is found that the fit between coupling and shaft is too loose, which affects the concentricity of holes and shafts, it should be repaired. It is an expedient measure to dot the axle or pad the copper sheet, which can not be used as an ideal method.

What’s special about bolts that can bear 18 tons

Bolts made of high-strength steel or requiring large preloading force can be called high-strength bolts. High-strength bolts are mostly used to connect bridges, rails, high-pressure and ultra-high-pressure equipment. The fracture of this kind of bolt is mostly brittle fracture. In order to ensure the sealing of the container, large prestressing force is needed for the high strength bolts used in the ultra-high pressure equipment.

Processing Technology of High Strength Bolt

Hot rolled wire rod – (cold drawing) – spheroidizing (softening) annealing – mechanical descaling – Pickling – cold drawing – cold forging – thread processing – heat treatment – Inspection

Special High Strength Bolts

Usually, high strength bolts can bear more load than ordinary bolts of the same specification. Common bolts are made of Q235 (A3). High strength bolts are made of 45 # steel, alloy steel (such as 20MnTiB, 35VB) or other high quality materials, which are then heat treated to improve strength.

The mechanical performance requirements of common bolts of the same grade are slightly higher than those of high-strength bolts, but the acceptance requirements of impact work of high-strength bolts are more than that of ordinary bolts.

Identification style comparison:

The mark of common bolt and high strength bolt is the basic method of identifying the same grade bolt on site. Because the values of high-strength bolt torque calculated in Anglo-American standards are different, it is necessary to identify the bolts of the two standards.

The difference between them is the strength of the material.

From the view of raw materials: high strength bolts are made of high strength materials. The bolts, nuts and washers of high strength bolts are made of high strength steel, commonly used 45 steel, 40 boron steel, 20 manganese titanium boron steel. Common bolts are usually made of Q235 steel.

From the strength level, 8.8 and 10.9 strength grades are commonly used, of which 10.9 grade is the most. The strength grade of ordinary bolts is lower, generally 4.4, 4.8 and 5.6. (8.8S and 10.9S are special for steel structures)

Nowadays, advanced manufacturing represented by large aircraft, large power generation equipment, automobiles, high-speed trains, large ships and large complete sets of equipment will enter an important development direction. As a result, fasteners will enter an important stage of development. High strength bolts are used for connection of important machinery. Repeated disassembly or various installation torque methods require high strength bolts. Therefore, the surface condition and thread accuracy will directly affect the service life and safety of the main engine. In order to improve the friction coefficient and avoid rusting, biting or jamming during use, the technical requirements stipulate that the surface should be nickel-phosphorus plated. The thickness of the coating is guaranteed to be in the range of 0.02-0.03 mm. The coating is uniform, compact and without pinholes.

Type Characteristics and Improvement Scheme of Metal Boring Technology

Boring refers to the further processing of forged, cast or drilled holes. Boring can enlarge the aperture, improve the accuracy, reduce the surface roughness, and better correct the deviation of the original hole axis. In the process of ultra-precision boring, in order to make the boring rod withdraw from the workpiece for loading and unloading the workpiece, a tool groove is set up in the rear guide. Following is an introduction to various aspects of Borun Petrochemical Company on the types of downhole boring technology and the ways to improve it.

I. Characteristics of Boring Technology

(1) Boring machine has many parts which can work in feed motion, so that it has multi-function in technology and shows strong adaptability. It can not only process the surface of cylindrical hole, plane, groove, thread and central hole, but also process many kinds of parts, which is convenient to realize the processing of hole system.

(2) Boring process takes tool rotation as the main motion, which is especially suitable for processing large-scale parts with complex structure, such as box and frame, compared with workpiece rotation as the main motion.

(3) The greatest feature of boring is that it can correct the hole axis deviation and deviation caused by the previous process.

Types of Boring Technology

(1) Supporting Boring Method

Supporting boring method is a kind of cutting method which uses the supporting boring rod in the tailstock sleeve of boring machine. The characteristics of the support boring method are as follows:

Compared with the cantilever boring method, the rigidity of the boring bar is greatly enhanced.

(2) Suitable for the processing of coaxial holes. It can be equipped with a variety of high precision boring cutters, with high processing accuracy and guaranteed processing quality.

(3) It is difficult and time-consuming to fix and adjust the boring cutter. It is not easy to observe the processing situation. The operation of trial boring and measurement is not as intuitive and convenient as the cantilever boring method.

(2) Suspension Boring Method

A single overhanging boring tool bar is used to boring medium-sized and non-perforated coaxial holes. This method is called overhanging boring method. The main features of the cantilever boring method are as follows:

As the boring rod used in the cantilever boring is generally short, thick and rigid, the selection of cutting speed can be higher than that of the supporting boring rod, so the production efficiency is high.

(2) It is convenient to clamp and adjust the cutter on the overhanging boring rod, and it is also convenient to observe and measure in the process, which can save auxiliary time.

(3) When the spindle is fed into the cutting by the cantilever boring method, the deflection of the tool rod system is different due to the change of self-weight because the boring rod is continuously cantilevered with the spindle, and the axis of the hole is prone to bend when the longer inner hole is machined. As the spindle extends continuously, the rigidity of the whole tool bar system becomes worse and worse. Under the action of cutting force, the elastic deformation of the system increases gradually, which affects the boring accuracy of the hole and causes the cylindricity error of the machined hole.

II. Improvement of Boring Technology

In order to reduce cutting force, eliminate cutting vibration and improve machining efficiency, effective improvements can be made by adjusting cutting angle, improving tool material and selecting high-end cutting oil.

(1) Adjustment of cutting angle

It is generally believed that the negative rake angle should be used to increase the strength of cutting tools for processing brittle materials such as cast iron so as to prevent the tool from breaking. But the rake angle has the greatest influence on the cutting force among the geometric parameters of the tool. Without reducing the cutting parameters, it can effectively reduce the cutting force, not only make the cutting faster, but also effectively reduce the occurrence of cutting vibration.

(2) Installation method of blade

Ultra-hard blades such as cubic boron nitride and cermet with common clamping method can not make positive rake angle on the blade, but making positive rake angle on the tool will increase the difficulty of installation and adjustment of the blade. In most cases, the chip breaking effect of vertical inserts is better, the chip holding space is more reasonable, the chip removal is smoother, and the stable processing process is easier to obtain.

(3) Blade material and structure

Ceramic cutting tool is a new material tool in modern metal cutting. Its characteristics are high hardness, high strength, high red hardness, high wear resistance, excellent chemical stability and low friction coefficient. However, the boring process is continuous cutting, and there is no impact in the cutting process, so ceramic blades can also be used in rough boring.

(4) Selection of Boring Cutting Oil

The performance of cutting oil in boring technology directly determines the accuracy of workpiece, so when choosing cutting oil, the appropriate cutting oil is selected according to the different material of workpiece. For materials that are easy to cut, low viscosity is usually chosen to prevent burrs on the premise of cleanability of finished products. Harder workpieces should use boring oil containing sulfur-chlorine compound additives, but the problem of rust should be avoided by degreasing as soon as possible after processing.

These are the common types and improvement methods of boring technology. Reasonable use of equipment, tools and cutting oil can effectively reduce errors and improve workpiece accuracy.