Use and performance of Japanese die steel materials

SLD Japan Hitachi High Wear Resistance Alloy Cold Work Tool Steel
Main components% carbon 1.5, manganese 0.45, chromium 12.0, molybdenum 1.0, vanadium 0.35

Factory state: Annealed HB≤230

Quenching: preheat at 700~750℃, then heat, 1.000~1.050℃, and cool in still air, such as steel with thickness of 6 inches or more…

SLD Japan Hitachi High Wear Resistance Alloy Cold Work Tool Steel

Main components% carbon 1.5, manganese 0.45, chromium 12.0, molybdenum 1.0, vanadium 0.35

Factory state: Annealed HB≤230

Quenching: preheat at 700~750℃ and then heat, 1.000~1.050℃, and cool in still air. For example, if the thickness of steel tools is more than 6 inches, heat to 980~1030℃, hardening in oil is better

Tempering: Heat to 150~200℃ and stay at this temperature, then cool in still air, tempering should be completed in the second time.

Hardness: HRC57℃~62℃

Annealing: Heat to 800~850°C, stay at this temperature for 1~3°C for hours, and let it cool in the furnace.

Forging: 1050~950℃

Uses: This steel is easy to turn, and it is suitable to make sharp knife edges, scissors, circular saws, cold or hot work trimming dies, drum edges, screw patterns, wire dies, milling cutters, punching dies, round drums, and making power transformer core punching dies ,Cutting steel sheet rolling knife, steel tube forming drum, and making the craftsman drum, special forming drum, precision gauge, complicated shapes. Cold pressing tools, tin molds, plastic molds, plastic molds, screw heading molds, etc.

DAC Hitachi High Quality Hot Work Tool Steel

Main components% Carbon 0.4 Silicon 1.0 Manganese 0.4 Chromium 5.3 Molybdenum 1.5 Vanadium 1.1

Factory state: Annealing≤HB250

Forging: 1.050~850℃

Annealing: Heat to 800~850°C, stay at this temperature for three hours, and let it cool down in the furnace.

Tempering: first preheat to 550~680℃ and stay at this temperature, then cool in still air, and temper twice.

Quenching: first preheat to 550~600℃, second heating 850~900℃

Hardness: Below HRC53℃

Uses: This steel contains tungsten and high temperature resistant high-grade alloy steel, suitable for hot work, aluminum, magnesium, zinc, copper alloy die casting molds, grooving knives, scissors and hot forging operations, plastic molds, hot work reamers, rolling Knives, general hot forging dies, hot tools, etc.

FDAC Hitachi brand special die-casting die alloy steel

Steel characteristics: FDAC series DAC (JIS SKD 61) is the basic component, and free-cutting alloy is added, and it is manufactured with a special dissolution method.

Steel number

1. Overview of my country’s steel grade representation method
Steel grades are referred to as steel grades, which are the names for each specific steel product and are a common language for people to understand steel. Our country’s steel grade representation method is based on national standards

The “Method of Representation of Steel Product Grades” (GB221-79) stipulates that the combination of Chinese pinyin letters, chemical element symbols and Arabic numerals shall be used for expression. which is:

① The chemical elements in steel grades are represented by international chemical symbols, such as Si, Mn, Cr… etc. Mixed rare earth elements are represented by “RE” (or “Xt”).

②Product name, use, smelting and pouring methods, etc., are generally expressed in Chinese pinyin abbreviations, see the table.

③The main chemical element content (%) in steel is expressed by Arabic numerals.

2. Classification description of the representation method of steel number in my country

1. Carbon structural steel

① Consists of Q+number+quality grade symbol+deoxidation method symbol. Its steel number is prefixed with “Q”, which represents the yield point of the steel, and the following number represents the value of the yield point, in units

For example, Q235 represents a carbon structural steel with a yield point (σs) of 235 MPa.

②If necessary, a symbol indicating the quality level and deoxidation method can be marked after the steel number. The quality grade symbols are A, B, C, D. Symbol of deoxidation method: F means boiling steel; b table

Shows semi-killed steel: Z stands for killed steel; TZ stands for special killed steel. Killed steel may not be marked with symbols, that is, both Z and TZ may not be marked. For example, Q235-AF represents Class A boiling steel.

③ Carbon steel for special purposes, such as bridge steel, ship steel, etc., basically uses the expression method of carbon structural steel, but the letter indicating the purpose is added at the end of the steel number.

2. High-quality carbon structural steel

① The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten-thousandths of the average carbon content. For example, for steel with an average carbon content of 0.45%, the steel number is “45”.

Serial number, so it cannot be read as 45 steel.

②High-quality carbon structural steel with high manganese content should be marked with manganese, such as 50Mn.

③ Boiling steel, semi-killed steel and high-quality carbon structural steel for special purposes should be specially marked at the end of the steel number. For example, the steel number of semi-killed steel with an average carbon content of 0.1% is 10b.

3. Carbon tool steel

①The steel number is prefixed with “T” to avoid mixing with other steels.

②The number in the steel number indicates the carbon content, expressed in thousandths of the average carbon content. For example, “T8” means that the average carbon content is 0.8%.

③For those with higher manganese content, mark “Mn” at the end of the steel number, such as “T8Mn”.

④The phosphorus and sulfur content of high-grade high-quality carbon tool steel is lower than that of general high-quality carbon tool steel. Add the letter “A” at the end of the steel number to show the difference, such as “T8MnA”.

4. Free cutting steel

①The steel number is prefixed with “Y” to distinguish it from high-quality carbon structural steel.

②The number after the letter “Y” indicates the carbon content, expressed in ten-thousandths of the average carbon content. For example, a free-cutting steel with an average carbon content of 0.3% has a steel grade of “Y30”.

③ Those with higher manganese content are also marked with “Mn” after the steel number, such as “Y40Mn”.

5. Alloy structural steel

① The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten-thousandths of the average carbon content, such as 40Cr.

②The main alloying elements in steel, except for individual microalloying elements, are generally expressed in a few percent. When the average alloy content is less than 1.5%, generally only the element symbol is indicated in the steel number, and

The content is not indicated, but in special circumstances it is easy to cause confusion, the number “1” can also be marked after the element symbol, such as steel number “12CrMoV” and “12Cr1MoV”, the former contains chromium

The amount is 0.4-0.6%, the latter is 0.9-1.2%, and the rest of the ingredients are all the same. When the average content of alloying elements is ≥1.5%, ≥2.5%, ≥3.5%…, the element symbol should be

Indicate the content, which can be expressed as 2, 3, 4, etc. accordingly. For example, 18Cr2Ni4WA.

③ Alloying elements such as vanadium V, titanium Ti, aluminum AL, boron B, and rare earth RE in steel are all microalloying elements. Although the content is very low, they should still be marked in the steel number. For example, in 20MnVB steel.

Vanadium is 0.07-0.12%, and boron is 0.001-0.005%.

④High-grade high-quality steel should add “A” at the end of the steel number to distinguish it from general high-quality steel.

⑤ Special purpose alloy structural steel, the steel number is prefixed with (or suffix) the symbol representing the purpose of the steel. For example, 30CrMnSi steel special for riveting screws, the steel number is expressed as ML30CrMnSi.

6. Low alloy high strength steel

① The representation method of steel grade is basically the same as that of alloy structural steel.

②For professional low-alloy high-strength steel, it should be indicated at the end of the steel number. For example, 16Mn steel, the special steel grade for bridges is “16Mnq”, and the special steel grade for automobile beams is “16MnL”

The special steel grade for pressure vessels is “16MnR”.

7. Spring steel

Spring steel can be divided into two types: carbon spring steel and alloy spring steel according to its chemical composition. The steel number expression method is basically the same as that of high-quality carbon structural steel.

The steel is the same.

8. Rolling bearing steel

①The steel number is prefixed with the letter “G”, which indicates the type of rolling bearing steel.

② The carbon content of high carbon chromium bearing steel grades is not marked, and the chromium content is expressed in parts per thousand, such as GCr15. The steel number representation method of carburized bearing steel is basically the same as that of alloy structural steel.

9. Alloy tool steel and high-speed tool steel

① When the average carbon content of alloy tool steel grades is ≥1.0%, the carbon content is not marked; when the average carbon content is <1.0%, it is expressed in parts per thousand. For example Cr12, CrWMn, 9SiCr,


②The expression method of alloy element content in steel is basically the same as that of alloy structural steel. But for alloy tool steel grades with lower chromium content, the chromium content is expressed in parts per thousand, and is

Add “0” to the number indicating the content to distinguish it from the general element content expressed by a few percent. For example, Cr06.

③The steel grades of high-speed tool steels generally do not indicate the carbon content, only a few percent of the average content of various alloying elements. For example, the steel grade of tungsten high-speed steel is expressed as “W18Cr4V”.

Steel grades with the letter “C” indicate that their carbon content is higher than that of general steel grades without a “C”.

10. Stainless steel and heat-resistant steel

① The carbon content in steel grades is expressed in parts per thousand. For example, the average carbon content of “2Cr13″ steel is 0.2%; if the carbon content of the steel is ≤0.03% or ≤0.08%, the steel number is marked with ”

00″ and “0” mean it, such as 00Cr17Ni14Mo2, 0Cr18 Ni9, etc.

②The main alloying elements in steel are expressed in a few percent, while titanium, niobium, zirconium, nitrogen, etc. are marked according to the above-mentioned method of expressing microalloying elements in alloy structural steels.

11. Electrode steel

Its steel number is prefixed with the letter “H” to distinguish it from other steels. For example, the stainless steel welding wire is “H2Cr13”, which can be distinguished from the stainless steel “2Cr13”.

12. Silicon steel for electrical engineering

①The steel number is composed of letters and numbers. The head letter DR of the steel number indicates hot-rolled silicon steel for electrical purposes, DW indicates cold-rolled non-oriented silicon steel for electrical purposes, and DQ indicates cold-rolled oriented silicon steel for electrical purposes.

②The number after the letter represents 100 times the iron loss value (W/kg).

③If the letter “G” is added to the end of the steel number, it means the test is performed at high frequency; the one without “G” means the test is performed at a frequency of 50 cycles.

For example, steel number DW470 indicates that the maximum iron loss per unit weight of cold-rolled non-oriented silicon steel products for electrical purposes at a frequency of 50 Hz is 4.7W/kg.

13. Pure iron for electricians

① Its brand name is composed of letters “DT” and numbers. “DT” means pure iron for electricians, and the number means the serial number of different grades, such as DT3.

②The letter added after the number indicates the electromagnetic performance: A-high grade, E-super grade, C-super, such as DT8A.

Manufacture of spiral extension springs and torsion spring

For important springs, strong pressure treatment is also required. The strong pressure treatment is to make the spring under the ultimate load load for 6 to 48h, so as to produce plastic deformation and residual stress in the dangerous area of ​​the spring wire section. Since the sign of the residual stress is opposite to the working stress, the maximum working stress of the spring after high pressure treatment is relatively small, and one high pressure treatment can increase the static load carrying capacity of the spring by 25%. If it is shot peening, it can increase by 20%. However, springs used in long-term vibration, high temperature and corrosive media, and springs for general purposes should not adopt this strengthening process.

In the manufacture of spiral tension and torsion springs, at present, except for a few manufacturers who have introduced foreign CNC numerical control spring forming machines to automatically form and process various styles of tension and torsion springs at one time. The vast majority of manufacturing plants still use traditional processing methods to manufacture, and here is a brief introduction.

1. Spiral tension spring. The process is basically the same as that of the helical compression spring. The only difference is the hook loop processing at the end. The forming method of the tension spring is as follows:

1) Use the same method as the spiral compression spring, after winding and forming, perform stress relief annealing, and then perform hook loop processing, except for special-shaped hook loops or spiral tension springs that require high initial tension. In addition to coiling, most springs are coiled by automatic spring coiling machines.

2) Use straight-tail spring coiling machine to roll. It is a vertical centered spring coiling machine with vertical mandrel. After rolling, stress relief annealing is performed, and then hook and loop processing is performed. There are many types of end structures of helical tension springs and many processing methods. Commonly used are: small springs are manually processed with pliers-type special tools or special process devices; ordinary spiral tension springs are processed by manual or automatic operation methods with hooks or molds; long arm hook and loop stretching For springs, the length of the material required for the hook is generally reserved during winding, or the number of turns required for processing is reserved after rolling. The ends are straightened with a straightening tool, and then the hook and loop is bent with a special tool.

The process specification of stress relief annealing is as described above. After the spring is coiled, stress relief annealing is performed first, and then cut and the shackle processing is performed. After the shackle processing is completed, the stress relief annealing is generally performed 1 to 2 times. In order to prevent the relative angle of the two shackles from changing, the temperature after the shackle processing should be 20-30°C lower than the temperature after the rolling during the stress relief annealing. Spiral tension springs are generally not subject to shot blasting and strong drawing.

2. Spiral torsion spring. The process is basically the same as that of the spiral compression and extension springs, and the difference is also embedded. In the case of small batch production and complicated torsion arms, most of them are formed by manual or semi-automatic mandrel coil springs, and then used The tooling and fixture will process the torsion arm according to the drawing requirements. In mass production, it can be rolled on a straight tail spring coiling machine and a special torsion spring machine. If the torsion arm cannot be completed according to the drawing, it can be processed by tooling and fixtures in the process. According to the characteristics of spiral torsion springs, the following two points should be paid attention to when designing and manufacturing:

1) The torsion arm at the end of the spiral torsion spring should be bent once during manufacture to avoid processing defects and corrective shaping. After the torsion arm is processed, the second stress relief annealing should be carried out;

2) The current spiral torsion springs are mostly dense coils, so that a compression force similar to the initial tension of the tension spring is generated between the coils. When loading and unloading, there will be friction and hysteresis. When the load is the same as the rotation direction or the number of turns increases, this tendency increases; in addition, it also brings difficulties to the surface treatment process. Therefore, when designing and forming, there should be a slight gap between the spring coils. In mass production, the manufacturer can use hydraulic and pneumatic methods to process the spiral stretching, torsion spring unfolding, bending, hooking and other processes if conditions permit.

Manufacture of spiral extension springs and torsion spring

Manufacture of spiral tension springs and torsion springs
1. Cylindrical spiral spring structure

According to the nature of the force, the cylindrical coil spring has three types:

1. Cylindrical spiral compression spring

1) The distance between each coil of the spring

Suppose the pitch of the spring is p; the diameter of the spring wire is d; there should be an appropriate spacing δ between the turns in the free state. In order to maintain a certain elasticity of the spring after compression, it should also be ensured that under the maximum load, there is still a certain distance δ1 between the rings. The size of δ1 is generally recommended as: δ1=0.1d≥0.2mm

2) Dead circle

The two end face rings of the spring are tight with the adjacent ring (no gap), and only play a supporting role without participating in deformation, so it is called a dead ring. When the number of working turns of the spring n≤7, the dead loop at each end of the spring is about 0.75 turns; when n>7, the dead loop at each end is about 1 to 1.75 turns.

3) End structure

YI type: Both end face rings are tightly tied to the adjacent rings, and they are ground on a special grinder;

Type YII: Both ends of the spring wire are forged flat and tightly tied to the adjacent ring during heating and winding (the end ring can be ground or not);

Type YIII: Both end rings are tightly aligned with the adjacent rings and are not flattened

In important occasions, the YI type should be used to ensure that the two supporting end faces are perpendicular to the axis of the spring, so that the spring will not skew when compressed. When the spring wire diameter d≤0.5mm, the two supporting end faces of the spring do not need to be ground flat. For springs with d>0.5mm, both supporting end faces need to be ground flat. The flattened part should be no less than 3/4 of the circumference. The end thickness is generally not less than d/8, and the end surface roughness should be less than

2. Cylindrical spiral tension spring

1) End hook type

In order to facilitate connection, fixation and loading of the tension spring, hooks are made at both ends.

The LI type and LII type hooks are easy to manufacture and are widely used. However, due to the large bending stress generated at the transition of the hook, it is only suitable for springs with a spring wire diameter d≤l0mm.

The LVII and LVIII type hooks are not integrated with the spring wire, so there is no shortcoming of the transition part mentioned above, and the hook can be turned to any direction for easy installation. In situations where the force is large, it is best to use the LVII type hook, but its price is more expensive.

2) Prestressed tension spring

When the cylindrical spiral tension spring is unloaded, the coils should be close to each other. In addition, in order to save the axial working space and ensure that the coils of the spring are pressed against each other when there is no load, often during the winding process, the spring wire is twisted around its own axis. The spring made in this way has a certain pressing force between each coil, and a certain prestress is also generated in the spring wire, so it is called. This kind of spring must only start to separate after the applied tension is greater than the initial tension F0, so it can save axial working space compared with tension springs without prestress.

3. Spiral torsion spring

The torsion spring, in order to facilitate connection, fixation and loading, there are lever arms at both ends:

(2) Manufacturing of cylindrical coil springs

The manufacturing process of the coil spring includes: a) rolling; b) hook making or finishing of the end face ring; c) heat treatment; d) process test and pressure treatment.

Rolling is to wind the spring wire that meets the technical requirements on the mandrel. In mass production, it is rolled on a universal automatic spring coiling machine; in single-piece and small batch production, it is rolled on an ordinary lathe or manual winding machine.

There are two types of rolling: cold rolling and hot rolling. Cold coil is used for spring wire with a diameter d<(8~10)mm drawn after pre-heat treatment; hot coil is used for strong spring made of spring wire with larger diameter. The temperature during hot coiling is selected within the range of 800-1000℃ depending on the thickness of the spring wire. Regardless of whether cold coil or hot coil is used, the pitch of the spring should be adjusted as necessary after coiling.

After completing the above-mentioned procedures, the spring should be heat treated. No significant decarburization layer should appear on the spring surface after heat treatment. The cold rolled spring is only tempered to eliminate the internal stress generated during the rolling.

In addition, the spring must be subjected to process tests and precision, impact, and fatigue tests according to the technical conditions of the spring to check whether the spring meets the technical requirements. It should be particularly pointed out that the durability and impact strength of the spring depend to a large extent on the surface condition of the spring wire, so the surface of the spring wire must be smooth and free of defects such as cracks and scars. Surface decarburization will seriously affect the durable strength and impact resistance of the material. Therefore, the depth of the decarburized layer and other surface defects should be specified in the technical conditions of the acceptance spring. Important springs must also be surface-protected (such as galvanized); ordinary springs are generally coated with oil or paint.

The meaning of stainless steel corrosion

The meaning of stainless steel corrosion
In a corrosive environment, the damage caused by the chemical or electrochemical effects of metal and surrounding media is called corrosion. In a corrosive environment, when stainless steel is incorrectly selected, corrosion will also occur. There are many ways to classify corrosion. spring

1. According to the nature of the action, it can be divided into chemical corrosion and electrochemical corrosion.

2. According to the form of corrosion, it can be divided into general (full and uniform) corrosion. The so-called general corrosion means that the corrosion is distributed on the entire stainless steel surface, the so-called local corrosion pitting corrosion, crevice corrosion, stress corrosion, corrosion fatigue, selective corrosion, erosion corrosion, etc.

3. According to the environment and conditions in which the corrosion occurs, it can be divided into atmospheric corrosion, industrial water corrosion, soil corrosion, acid, alkali, salt corrosion, sea water corrosion, high temperature corrosion, (including liquid metal, molten salt, gas corrosion), etc. The standard for stainless steel springs!

The effect of quenching liquid concentration and temperature on cooling rate

The water-based PAG quenching liquid controls its cooling capacity by controlling its concentration, temperature and stirring, and obtains a cooling range between water and oil. How to control the influence of concentration, temperature and flow rate on quenching liquid cooling rate.
1. The effect of concentration on cooling rate

Concentration is inversely proportional to the cooling rate, increasing the concentration and decreasing the cooling rate, conversely decreasing the concentration and increasing the cooling rate. Therefore, if you want to increase the cooling rate, add tap water to decrease the concentration, otherwise, add quenching solution to increase the concentration and decrease the cooling rate.

2. The influence of temperature on cooling rate

Simply put, the higher the temperature, the lower the cooling rate; the lower the temperature, the higher the cooling rate. Therefore, to increase the cooling rate, the quenching agent can be cooled during production to reduce the temperature; otherwise, heating or stopping the cooling cycle and increasing the quenching agent temperature can reduce the quenching cooling rate.

3. The effect of stirring on the cooling rate

Stirring the quenching liquid (package swinging workpiece) can increase its quenching cooling rate; on the contrary, reduce the quenching cooling rate.

Making good use of the influence of these three aspects on the cooling rate can solve many heat treatment problems.

What are the high temperature refractory materials

High-temperature resistant materials include refractory materials and heat-resistant materials, including inorganic compounds and polymer materials. Refractory materials generally refer to inorganic materials that can withstand temperatures above 1580°C. They are used to build kilns, combustion chambers and other building materials that need to withstand high temperatures. It is generally made of quartz sand, clay, magnesite, dolomite, etc. as raw materials, such as refractory cement and magnesia bricks. Broadly speaking, inorganic refractory and heat-resistant materials refer to these compounds that have high hardness, good brittleness, and good chemical resistance, and their melting point is above 1500. Mainly divided into two types: metal and non-metal compounds and non-metal compounds.

The former such as tungsten, molybdenum, tantalum, niobium, vanadium, chromium, titanium, zirconium and other refractory metals and rare earth metals such as borides, carbides, nitrides, silicides, phosphides and sulfides; the latter such as boron carbide, Silicon carbide, boron nitride, silicon nitride, boron phosphide, silicon phosphide, etc. The latter has extremely important uses, and can be used as high-temperature refractory materials (such as abrasives, molds, nozzles, high-temperature thermowells), heat-resistant materials (such as rocket structural components, nuclear engineering materials, electric heating components), electrical materials ( Such as high temperature thermocouple, ignition electrode), in addition, it is also used as chemical resistant materials and hard materials.

Heat-resistant polymers can be used as high-temperature resistant film insulation materials, high-temperature resistant fibers, high-temperature resistant coatings, and high-temperature resistant adhesives. According to the time of high temperature resistance, it is divided into instant high temperature resistant materials and longer time high temperature resistant materials. The former can withstand several seconds to several minutes at 1000~10000℃. Among them, the ablation material is also a high temperature resistant material. For example, at 300~600℃, it can maintain its mechanical strength and chemical corrosion resistance in the air.

Box annealing furnace

The box annealing furnace mainly uses special equipment for quenching, normalizing, annealing and other conventional heat treatment of steel workpieces. Its characteristics are: 1. The electric furnace has large loading capacity and high productivity, especially suitable for small and medium-sized parts.
The box annealing furnace mainly uses special equipment for quenching, normalizing, annealing and other conventional heat treatment of steel workpieces.

Its characteristics are:

1. The electric furnace has large loading capacity and high productivity. It is especially suitable for heat treatment and heating of small and medium-sized parts. It can save energy up to 30%, the furnace temperature is uniform, and the intelligent digital display PID automatically controls the furnace temperature with high precision;

2. The electric furnace is convenient to load imperial materials and has good operating conditions;

3. The furnace door and the furnace body are sealed automatically without manual sealing;

How to choose the valve

The selection of suitable valves needs to be checked one by one according to the following procedures, so that the selected valve can meet its function and perform the assigned task.
(1) Valve characteristics and main executive functions To understand the characteristics of various valves and their executive functions, this is the first step in selecting suitable valves. The characteristics, classifications and main executive functions of various valves are the first 2nd and 3rd. This section has been mentioned, and is now summarized into Table 1 and Table 2 for reference.

(2) Caliber or flow (capacity) “shown in Table 3”   A. The nominal diameter of the valve may not be the same as the diameter of the flow channel. The selected size is calculated from the condition of the conveying fluid to calculate the required Cv value, and then the Cv Value (refer to the manufacturer’s catalog) to select a suitable valve diameter.   B. Cv value is defined as the Cv value of the valve when the pressure drops at 1 when the water at 60 degrees Fahrenheit flows through the valve.  C.Cv value can calculate the flow rate (Q) flowing through the valve.  Q=CvΔP=7.9Cv  P=density of liquid, LB/FT3  ΔP=pressure drop after passing the valve, PSI

(3) Temperature VS pressure The “temperature VS pressure” of the valve refers to the allowable and safe pressure specified by the valve at a certain temperature (but this pressure is the maximum allowable pressure without impact). 5. Valve structure material The choice of valve structure material is extremely important in the functional life of the valve. However, the general valve structure material is mainly divided into two categories: A. Pressure main material: valve body, valve cover, Bottom cover, bolts, etc. The main factors considered in the selection of pressure main material:   a. Fluid temperature and pressure:   A) High temperature use: Metal materials generally are in high temperature environments, their tensile strength and life are reduced with the increase of temperature, and their creep The intensity also has an impact.  B) Low-temperature use: When metal materials are used in low-temperature applications, the toughness of their destruction is drastically reduced, resulting in low-temperature brittleness. b. Corrosion resistance of materials:    valve structure metal corrosion causes:    (A) fluid type (B) concentration (C) temperature corrosion damage form: (A) uniform corrosion (B) pitting corrosion (C) dezincification And peeling.

Problems in the use of metal crusher inspection

During the operation of the metal crusher, the coordination of each part must be close and reliable, the transmission must be correct and stable, and especially it should have good lubrication. Therefore, the inspection and maintenance of the metal crusher should focus on lubrication, tightening and adjustment.

A. Lubrication of metal crusher The metal crusher can only guarantee the long-term normal operation of the bearings and transmission gears under good lubrication conditions. The large gears with dead cylinders are well lubricated and maintained, and their lifespan can generally reach more than 15 years. However, if the maintenance is improper, it will be scrapped after only 1-2 years. Especially the semi-open transmission gears are more serious. Similarly, under normal lubrication and maintenance, the life of the main bearing bush can reach more than 10 years.

On the contrary, sometimes it needs to be replaced after 2-3 years. Major accidents of main bearing bush burning are often caused by poor lubrication. Therefore, the influence of reasonable lubrication on the friction parts of the metal crusher is extremely important. The lubrication of the friction surfaces of the metal crusher generally takes two forms, namely dry oil lubrication and thin oil lubrication. The large and small transmission gears, transmission bearings, reducers and main bearings of large and medium metal crushers are lubricated by thin oil circulation, and some large and small transmission gears and transmission shaft bearings of metal crushers are also lubricated by dry oil.

Practice has proved that the large and small transmission gears and sliding bearings are lubricated with thin oil while the rolling bearings are lubricated with oil. Thin oil lubrication is best with pressure circulating oil lubrication, which is extremely beneficial to the stable operation of the metal crusher and prolongs the service life of the parts. The transmission gears of small metal crushers are mostly oil lubricated, but thin oil lubrication is still better.

The lubrication system of the metal crusher is composed of oil pump, filter cooler, oil pressure regulating valve, oil tank, oil pipe and indicating instrument device. Lubricating oil is generally 30-50 mechanical oil. Lubricating oil is generally filtered or replaced every six months. For lubrication systems without filters, it should be filtered every quarter. When the large gear or main bearing of the cylinder is found to have thrown out the slurry, it should be inspected and cleaned immediately. Otherwise, it will cause rapid wear of the gear or bearing bush, and the inspection must be strengthened. In normal operation, the grease on the big gear is generally cleaned and replaced every 2-4 months.