- tempering test
Bolts, screws and studs of class 8.8~12.9 shall be tempered according to the minimum tempering temperature in actual production and kept at 10 °C for 30 min. On the same sample, the difference between the average values of the three points before and after the test shall not exceed 20 HV.
The tempering test can check the incorrect operation due to insufficient quenching hardness and too low temperature tempering to barely reach the specified hardness range, and ensure the comprehensive mechanical properties of the parts. In particular, threaded fasteners made of low-carbon martensitic steel are tempered at low temperatures. Although other mechanical properties can be achieved, the residual elongation fluctuates greatly when measured to ensure stress, much larger than 12.5 um. Moreover, sudden breakage can occur under certain conditions of use. In some automotive and construction bolts, sudden breakage has occurred. This can be reduced by tempering with a minimum tempering temperature. However, special consideration should be given to the manufacture of 10.9 bolts from low carbon martensitic steel.
2. Hydrogen embrittlement inspection
The sensitivity of hydrogen embrittlement increases as the strength of the fastener increases. For the externally threaded fasteners of 10.9 and above or the surface hardened self-tapping screws and the combination screws with hardened steel washers, the hydrogen removal treatment shall be carried out.
The hydrogen removal treatment is generally carried out in an oven or a tempering furnace at 190 to 230 ° C for 4 hours or more to diffuse hydrogen.
Threaded fasteners can be tightened by tightening on a special clamp to maintain the screw with a relatively constant stress, for 48 hours. After the loosening, the threaded fasteners will not break. This method is used as a method of checking for hydrogen embrittlement.
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What is the scope of use of body bolts now? What is the name of the body bolt? What is the way to body bolts? Let’s analyze and analyze together.
Body bolts alias carriage bolts, semi-circular head square neck bolts! This bolt was produced and used earliest 20 years ago! The original purpose is used for the combination of iron and wood on the carriage, so it is also called the body bolt. Because the head is a semi-circular head, there is a square neck under the head, also called semi-circle. Head square neck bolts, or large round head square neck bolts! The international code for body bolts can be divided into three types, GB14 GB12 GB794, and German standard can be divided into DIN603/Inch American-made, American-made British body bolts. Today’s modern body bolts are widely used in applications such as: electronics manufacturing, machinery and equipment, chemical industry, Valve industry, medical equipment industry, automobile industry, aviation industry, etc.
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DIN 603 bolts must comply with the relevant requirements during the installation process, so that the quality of DIN 603 bolts can meet the standard. Let’s take a look at the installation requirements of DIN 603 bolts.
- When assembling the DIN 603bolt connection pair, the side of the nut with the round table should face the chamfered side of the washer. For large hexagonal DIN 603bolted couplings, the chamfered side of the lower bolt head should face the bolt head.
2. When installing DIN 603 bolts, it is strictly forbidden to force the bolts (such as hammering). If it is not free to be introduced, the hole shall be trimmed with a tap. The maximum diameter of the hole after trimming shall be less than 1.2 times the bolt diameter. When repairing holes, in order to prevent iron filings from falling into it, the bolts around the holes should be tightened before reaming. It is forbidden to cut the hole by gas cutting.
3. When installing DIN 603 bolts, the friction surface of the components should be kept dry and should not be used in the rain.
4. When the DIN 603 bolt is tightened, only the torque is applied to the nut. Allow bolts only when space is limited.
5. The tightening of DIN 603 bolts is divided into initial screwing, double screwing and final screwing. The initial tightening torque is 50% of the construction torque, and the first bolt tightening is performed symmetrically with a quick wrench. The re-twisting torque is equal to the initial tightening torque, and the tower connecting bolts are fastened in a symmetrical star shape with a hydraulic wrench. In order to prevent omission, the high-strength bolts after initial screwing, double-threading, and final screwing should be marked with a color on the nut. After inspection, the DIN 603 bolt is marked with a different color on the nut.
6. When the DIN 603 bolt is screwed at the beginning, the second twist and the final screw, the bolts at the joint should be screwed in a certain order. Generally, the bolts should be tightened outward in the center of the bolt group.
7. The initial, double and final screwing of DIN 603 bolts should be completed on the same day. Do not finish the final screwing until the next day.
After reading the above, I believe everyone knows the installation requirements for DIN 603 bolts.
What are the main considerations for the selection of DIN 603 bolt materials?
Requirements for the mechanical properties of the bolt material, in particular the strength;
Requirements for the corrosion resistance of materials under working conditions;
The operating temperature requirements for the heat resistance (high temperature strength, oxidation resistance) of the material;
Requirements for material processing performance in terms of production process;
Other aspects, such as weight, price, and purchasing factors, should be considered.
After comprehensive consideration of these five aspects, determine the grade, variety, specifications and material standards of the selected bolts.
There are many kinds of bolts for the manufacture of materials. Among them, the bolts made of stainless steel are more textured in appearance, have better performance in strength, and have the advantages of corrosion resistance, easy manufacture, and good welding. Stainless steel bolts can be plated or heat treated for better performance and can be recycled.
The use of stainless steel as the material of the bolt can be said to have great advantages in all aspects of manufacturing, use or handling. Therefore, although the bolt is made of stainless steel, the cost itself is relatively high, and the cycle life is relatively short, but in the bolt solution However, it still belongs to a more economical one.
Use of nickel in bolts
Bolts used to rely on the use of nickel in the process of using stainless steel, but the price of bolts has also been greatly affected by the global price of nickel. In order to reduce the cost pressure and improve the competitiveness of the bolts, bolt manufacturers have found alternative materials and produced low-nickel DIN 603 bolts.
Stainless steel magnetic problem with bolts
If the bolt is made of stainless steel as the main material, you should also understand the magnetic problem of the stainless steel itself. Stainless steel is generally considered to be non-magnetic, but in fact, austenitic series materials may be magnetic after a certain processing process, but if it is considered that magnetic is the standard for judging the quality of DIN 603 bolts, it is also inaccurate.
Haiyan Yihui Hardware Technology Co., Ltd. and everyone to understand the specific standards of DIN 603 bolt production, and other details that need attention, together with us to understand all aspects of DIN 603 bolt production.
Other standards for DIN 603 bolt production are standards for the production of DIN 603 bolting work, drawing the drawing standards for the screw samples given by the customer, the tolerance standards for the production, the standard of the heads of the production masters, and the production of the screws. Electroplating standards and some testing standards, etc.
DIN 603 bolts are the tools used to fasten the objects of the objects. They are everywhere in our daily life and have become one of the indispensable parts in our daily life and work. Large to large machinery, small to machine parts. It is ubiquitous and versatile. Due to the wide variety of DIN 603 bolts, it is possible to achieve a wide range of applications. With the development of technology, DIN 603 bolts have entered a new stage of development, saving energy in their use and adapting to the development needs of society.
DIN 603 bolts are widely used in machinery, petrochemical, telecommunications, chemical, construction, power, textile, sports equipment, paper, sewage, shipbuilding, automotive and other industries. With the domestic economic living standards greatly improved the application range of DIN 603 bolts Will be more extensive.
DIN 603 bolts are fitted with mechanical or non-metallic mechanical parts to form high-strength, wear-resistant, high-precision standard internal threads. DIN 603 bolts can be used as a means of repair for quick and effective repair and repair of threaded holes of various important components after the thread has been machined incorrectly or has been repaired. In addition, DIN 603 bolts are used for metric and inch threaded hole conversion, which is very convenient and fast.
I believe that everyone will see a variety of bolts in their daily lives, from the bolts on the frame to the bolts on the rocket plane, so we can find that the bolts are everywhere in our lives, bolts Basically it has covered our lives.
Then there are many kinds of bolts, and one of the DIN 603 bolts is also widely used by everyone. What are the characteristics of DIN 603 bolts? Let the bolt manufacturer tell you in detail.
The use of DIN 603 bolts is very extensive. For example, stainless steel plates, engineering installations, metal steel plates and galvanized steel plates that we usually see are also applied to DIN 603 bolts. Then some general angle steel or channel steel and iron plates are combined with other metal materials to install DIN 603 bolts.
Since the DIN 603 bolt is used so widely, you must be wondering what it has. First of all, DIN 603 bolt drilling and tapping, its bonding force is very strong, can be completed once locked. In this way, you can save your construction time and greatly improve your work efficiency, so many factories use DIN 603 bolts.
Of course, to use DIN 603 bolts should also pay attention to its own quality, remember not to buy some inferior bolts for cheap, because this will cause a lot of safety hazards.
Metal stamping is a complex process that can include many metal forming processes – punching, punching, bending and perforating. Blanking: This process is about cutting rough outlines or product shapes. This phase is about minimizing and avoiding Burr, which increases your part cost and extends the lead time. This step is used to determine hole diameter, geometry/taper, edge to hole spacing and insert the first perforation. Blanking – Metal stamping design Bending: When you design a bend in a metal stamping, it is important to allow enough material – to ensure that the part and its blank are designed so that there is enough material to perform the bend. Some important factors to remember:
If the bend is too close to the hole, it may be deformed.
The width of the notches and tabs and the grooves should be at least 1.5 times the thickness of the material. If they are made smaller, they are difficult to form because the force exerted on the punch causes them to break. The radius of each corner in the blank design should be at least half the thickness of the material.
To minimize the number and severity of burrs, avoid sharp corners and complex cuts as much as possible. If these factors cannot be avoided, be sure to pay attention to the burr direction in the design to take these factors into account during the stamping process.
Imprint: This action is when the edge of the stamped metal part is crushed or broken; this creates a smoother edge in the molded area of the part geometry; this also adds extra strength to the local area of the part. This can be used to avoid secondary machining such as deburring and grinding.
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First, hot-dip galvanized DIN 603 bolt features
The hot-dip galvanized DIN 603 bolt is obtained by immersing the rust-removed steel in a zinc solution melted at about 500 ° C to adhere the zinc layer to the surface of the bolt to prevent corrosion. The galvanized layer is relatively strong. The galvanized layer is relatively strong. Cold galvanizing, relatively no heating, little galvanizing, galvanized parts are easy to fall off when exposed to moisture. The fundamental difference between hot-dip galvanizing and cold-galvanizing is: Hot-dip galvanizing, also known as hot dip galvanizing, melts the zinc ingot by high temperature, puts the auxiliary material, and then immerses the metal structural member in the galvanizing bath. The advantage of hot-dip galvanized DIN 603 bolt is that it has strong anti-corrosion ability. The hardness of the galvanized layer of the bolt is better. “Cold plating” means “electroplating”, that is, the zinc salt solution is electrolyzed, and the plating part is coated without heating. The amount of zinc is very small, and it is easy to fall off when it is wet. Hot-dip galvanizing is a chemical treatment and belongs to an electrochemical reaction. Cold galvanizing is a physical treatment, only a layer of zinc is applied on the surface, so… Hot galvanizing is the galvanization of the steel surface under hot dip conditions. It has strong adhesion and is not easy to fall off. Hot galvanizing Although the tube also shows rust, it can meet technical and sanitary requirements in a long period of time.
First of all, the difference in process is that hot-dip galvanizing is to remove the oil, pickle, dipping, drying and immersing in the melted zinc solution for a certain period of time.
Second, hot-dip galvanizing has the following advantages compared with electro-galvanizing
(1) It can produce a thick coating layer, and has both a pure zinc layer and an iron-zinc alloy layer, so the corrosion resistance is good;
(2) The production efficiency of hot-dip galvanizing is particularly high; the time for the parts staying in the galvanizing hot bath is short
(3) Compared with electro-galvanizing, hot-dip galvanizing has lower production costs and has less impact on the environment than electroplating;
DIN 603 bolt raw materials and related technologies are lagging behind. An important reason for the poor quality of DIN 603 bolt products is the poor quality of raw materials and the backwardness of related technologies. For example, cold heading steel wire cold heading steel is mainly used to manufacture fasteners such as bolts, nuts, rivets and bolts. Its chemical composition and metallographic arrangement are relatively high. Now the annual demand for cold heading steel is about 1 million tons. In the meantime, the automobile industry demanded 100,000 tons. However, due to technical reasons, the domestically produced cold-rolled steel wire only needs 300,000 tons, and imports nearly 700,000 tons per year.
The DIN 603 bolt process and process equipment are of low level, and the DIN 603 bolts do not guarantee the consistency of product quality. The mechanical basic parts are generally batch and many products, and there are also many kinds of products and processing precision requirements. Therefore, the production process and equipment are required to be high and the capital is large. Foreign countries have chosen high-efficiency and high-precision special planes, production lines or flexible lines, and have completed high-efficiency automated production.
DIN 603 bolts are critical to the manufacture and inspection of equipment. Mechanical universal parts have high requirements for standard accuracy, functional reliability and interchangeability of each part. DIN 603 bolts only allow very few products to be out of tolerance, and It is checked out before the factory to remove the unqualified products. It is assumed that there is no high-precision and high-efficiency equipment, and it is difficult for the company to live and open in the fierce competition. At present, the key equipment of China’s parts and components production enterprises is mainly relying on imports, because the wear and tear of equipment is large, and the equipment demand is constantly updated and transformed. The imported equipment and spare parts are expensive, and it is necessary to speed up the handling of critical equipment if you want to speed up the operation.
DIN 603 bolt product development speed problem. China’s mechanical parts operations are far behind in terms of technological innovation and new product development, especially for SMEs, which lacks technical strength and talents, short funds and necessary equipment, and less information about technology and technology communication, resulting in long-term tracking. In the imitation stage, there are very few intellectual property rights. Now there are not many researches on the development of DIN 603 bolt products. There are few independent research and development efforts in the enterprise. This is a key issue for the continued development of the operation.