Tag Archive for: supplier

Posts

7 types of flange sealing surface: FF, RF, M, FM, T, G, RTJ

Flanged butterfly valve has a flange on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flange. Do you know all the 7 types of flange sealing surfaces? FF, RF, MF, M, T, G, RTJ
The flange sealing surface basically has:

Full plane: FF
Raised face: RF
Concave/female: FM
Convex/Male: M
Tenon: T
Groove surface: G
Ring connection surface RTJ (RJ)  types, according to the different working conditions, medium, pressure, specifications, temperature, etc., so the selected types are not the same. Let’s get to know the types of these flange sealing surfaces together!
FF-full plane:
Flat Face Full Face type sealing surface is completely flat, suitable for occasions where the pressure is not high and the medium is non-toxic.

flange FF

flange FF 

RF-raised face:
The Raised Face type of sealing surface is the most widely used among several types, and the most commonly used one. The international standards, European system and domestic standards are all fixed heights, but in the American standard flange, it should be noted that the height of high pressure will increase the sealing surface. There are also many types of gaskets used. Gaskets suitable for raised face sealing surface flanges include various non-metallic flat gaskets, coated gaskets; metal-wrapped gaskets; spiral wound gaskets (including outer ring or inner and outer ring).

flange RF

flange RF

Convex/Male: M
Concave /female: FM
The two types of sealing surfaces, Male Face and Female Face, are a pair, one female and one male. They must be used together. They are easy to align and prevent the gasket from being extruded. Suitable for occasions with higher pressure.
The suitable sealing gaskets for the concave-convex sealing surface include: various non-metallic flat gaskets and coated gaskets; metal-clad gaskets; basic type or winding stopper with inner ring, etc.
T-tenon
G-groove surface
Tongue Face and Groove Face are similar to the concave-convex surface. They are also a male and female matched sealing surface type, and they are also used in pairs. The gasket is located in the annular groove and is restricted by the metal walls on both sides. It can prevent the gasket from being compressed and deformed and squeezed into the pipeline. Since the gasket is not in direct contact with the fluid medium in the pipe, it is less eroded or corroded by the fluid medium, so it can be used for high pressure, flammable, explosive, and toxic mediums that require strict sealing. This kind of sealing surface gasket has good installation and neutrality, but it is difficult to process the sealing surface. It is easy to damage the sealing surface when replacing the gasket, and the flange must be separated in the axial direction during installation and disassembly. Therefore, consideration should be given to the pipeline design. It is possible to separate the flange in the axial direction.
Suitable gaskets for the sealing surface of the tongue and groove surface include: various metal and non-metal flat gaskets, metal-clad gaskets and basic spiral wound gaskets.

flange TG-

flange TG-

RTJ(RJ)-Ring connection surface
The flange of the Ring Joint Face seal is also a narrow-face flange, and an annular trapezoidal groove is opened on the flange surface as the flange sealing surface, which is the same as the tongue-and-groove flange. The flange must be separated in the axial direction during installation and disassembly. Therefore, the possibility of separating the flange in the axial direction should be considered in the pipeline design.
The sealing surface is specially designed to cooperate with solid metal gaskets processed into octagonal or elliptical shapes from metal materials to achieve a sealed connection. Since the metal ring gasket can be based on the inherent characteristics of various metals, the sealing performance of this sealing surface is good, and the installation requirements are not too strict. It is suitable for high temperature and high pressure working conditions, but the processing accuracy of the sealing surface is relatively high. (According to the Pipe Fittings, Pumps and Valves Alliance)

flange-RTJ-RJ-

flange-RTJ-RJ-

flange-RTJ-RJ-02

flange-RTJ-RJ-02

The difference between carbon steel and cast steel

What is the difference between cast steel and carbon steel? First, steel is classified by chemical composition
(1) Carbon steel: a. Low carbon steel (C≤0.25%) b. Medium carbon steel (C≤0.25~0.60%) c. High carbon steel (C≤0.60%)
Steel is classified according to the forming method: (1) Forged steel (2) Cast steel (3) Hot rolled steel (4) Cold drawn steel. The so-called cast steel and carbon steel are just the names produced by the different classifications of steel.

What is the difference between forged steel valve and cast steel valve? Forging and casting are two different

flanges

flanges

processing techniques.
Casting: The molten liquid metal fills the cavity and cools. Pores are easy to produce in the middle of the workpiece.
Forging: It is mainly formed by extrusion at high temperature. Can refine the crystal grain in the part.
Forging: Use hammering and other methods to make a metal material in a plastic state into a workpiece with a certain shape and size, and change its physical properties.
Casting: The metal is heated and melted and poured into a sand mold or mold, and solidified into a utensil after cooling.
The difference in performance
During forging, the metal undergoes plastic deformation to refine grains.

What is the difference between a cast iron valve and a cast steel valve? The main difference between cast iron and cast steel valves is the carbon content, which directly affects the strength and plasticity of the steel. Carbon steel is also called carbon steel, an iron-carbon alloy with a carbon content of less than 2% WC. In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur, and phosphorus. According to its purpose, carbon steel can be divided into three types: carbon structural steel, carbon tool steel and free-cutting structural steel. Carbon structural steel is divided into building structural steel and machine-manufactured structural steel. According to the carbon content, carbon steel can be divided into low-carbon steel (WC ≤ 0.25%) and medium-carbon steel (WC0.25%-0.6%) And high-carbon steel (WC>0.6%) According to phosphorus and sulfur content, carbon steel can be divided into ordinary carbon steel (higher phosphorus and sulfur), high-quality carbon steel (lower phosphorus and sulfur) and high-quality Steel (lower phosphorus and sulfur) Generally, the higher the carbon content of carbon steel, the higher the hardness and the higher the strength, but the lower the plasticity.
The full name of carbon steel is carbon structural steel. Cast steel valves are also carbon steel valves (there are also cast iron valves). They are just made by casting methods, while common steels are made by rolling. The ingredients are the same.

What is the difference between cast steel, cast iron and carbon steel in valve materials? Simply put, you first

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

distinguish between iron and steel. Both steel and iron are alloys based on iron and carbon as the main additive element, collectively referred to as iron-carbon alloys.
The cast iron is smelted in an iron melting furnace to obtain cast iron (liquid), and the liquid cast iron is cast into a casting, which is called a cast iron.
What is the difference between cast steel and carbon steel. First, steel is classified by chemical composition
(1) Carbon steel: a. Low carbon steel (C≤0.25%); b. Medium carbon steel (C≤0.25~0.60%); c. High carbon steel (C≤0.60%).
Steel is classified according to the forming method: (For valves with different pressures, different materials are used.
Medium and low pressure valve, the valve body material is cast iron. For high-pressure valves, because of the large pressure, the valve body must be made of cast steel. Special valves may use various alloy materials and stainless steel.
It is said that carbon steel is only a kind of steel, and cast steel is a processing method of steel, not a concept.

What is the difference between carbon steel gate valve and cast steel gate valve. Many people think that carbon steel gate valves and cast steel gate valves are two kinds of materials.
1. The cast steel check valve and carbon steel check valve are check valves of the same material, both of which are made of WCB A216 carbon steel.
2. Cast steel check valve, because the valve body of WCB material is cast, so the name suggests, it is called cast steel check valve.
3. Carbon steel check valve, because the main material of WCB material is carbon steel, it is named carbon steel check valve.

The forging process of steel is different in processing form. Cast steel The steel used for pouring castings. A kind of casting alloy. Cast steel is divided into cast carbon steel, cast low alloy steel and cast special steel. Cast steel refers to a type of steel casting produced by casting methods. Cast steel is mainly used to manufacture some parts with complex shapes, difficult to forge or cutting and forming, but require high strength and plasticity. Forged steel: Forged steel refers to various forgings and forgings produced by forging methods. The quality of forged steel parts is higher than that of cast steel parts, can withstand large impact forces, and have plasticity, toughness and other mechanical properties.

What is the meaning of cast steel and carbon steel of the valve? What is the meaning of cast steel and carbon steel. Thank you. Carbon steel is represented by CS, but it is generally not mentioned in the case of cast steel. Detailed materials such as WCB, WCC, LCC, etc. will be stated.

The valve is a control component in the fluid conveying system. It has the functions of cut-off, regulation, diversion, prevention of reverse flow, stabilization, diversion or overflow and pressure relief. Valves used in fluid control systems, ranging from the simplest shut-off valve to the various valves used in extremely complex automatic control systems, have a wide variety and specifications.
Valves can be used to control air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. >>Cast steel has less carbon content, good toughness, and higher pressure and temperature resistance than cast iron. Cast iron valves are not suitable for diesel, sea water and acid media. Cast iron valves are cheaper. Their materials are obviously different, and they are used in different environments! The cost is also different. In short, the price is analyzed in detail, and the properties of various materials are different. Temperature resistant. Cast steel valves can withstand high temperatures, but cast iron valves cannot be used with water.

Main application areas of 10 major types of valves

With the development of society and various needs of modern life, spare parts for the production of these important products are also emerging in endlessly areas. Below we list the main application areas of these 10 categories of

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

valves.

1. Valves for petroleum installations;

1) Oil refining plant,
Most of the valves used in oil refining equipment are pipeline valves, mainly gate valves, stop valves, check valves, safety valves, ball valves, butterfly valves, and traps. Among them, gate valves account for about 80% of the total number of valves (valves account for about 80% of the total number of valves). 3% to 5% of investment);

2) Chemical fiber device,
Chemical fiber products mainly include polyester, acrylic and vinylon. Ball valves and jacketed valves (jacketed ball valves, jacketed gate valves, jacketed stop valves) of the valves they need;

3) Acrylonitrile device.
The device generally requires standard valves, mainly gate valves, globe valves, check valves, ball valves, traps,

lift-swing-check-valve-2

lift-swing-check-valve-2

needle globe valves, and plug valves. Among them, gate valves account for about 75% of the total valve;

4) Synthetic ammonia plant.
Because the ammonia source and purification method are different, the process flow is different, and the technical function of the required valve is also different. At present, domestic ammonia plants mainly need gate valves, globe valves, check valves, traps, butterfly valves, ball valves, diaphragm valves, regulating valves, needle valves, safety valves, high temperature and low temperature valves;

2, Hydropower station application valve
The construction of power stations in my country is developing towards large-scale, so large-caliber and high-pressure safety valves, pressure reducing valves, stop valves, gate valves, butterfly valves, emergency shutoff valves and flow control valves, spherical sealing instrument stop valves are required (according to the country In the “Tenth Five-Year Plan”, in addition to Inner Mongolia and Guizhou provinces, which can build units with more than 200,000 kilowatts, other provinces and cities can only build units with more than 300,000 kilowatts);

3, metallurgical application valve
The behavior of alumina in the metallurgical industry mainly requires wear-resistant slurry valves (in-flow stop valves) and regulating traps. The steelmaking industry mainly needs metal sealed ball valves, butterfly valves and oxidation ball valves, stop flash and four-way reversing valves;

13 gate-valve-5

13 gate-valve-5

4, marine application valve
With the development of offshore oilfield exploitation, the amount of valves required for its offshore production has gradually increased. Offshore platforms need to use shut-off ball valves, check valves, and multi-way valves;

5, food and medicine application valve
This industry mainly needs stainless steel ball valves, non-toxic all-plastic ball valves and butterfly valves. Among the above 10 categories of valve products, the demand for general valves is more, such as instrument valves, needle valves, needle globe valves, gate valves, globe valves, check valves, ball valves, and butterfly valves.

6, rural and urban construction application valves
The urban construction department generally uses low-pressure valves, and is currently developing in the direction of environmental protection and energy saving. Environmentally friendly rubber plate valves, balance valves, centerline butterfly valves, and metal seal butterfly valves are gradually replacing low-pressure iron gate valves. Most of the valves used in domestic urban construction are balance valves, soft-seal gate valves, butterfly valves, etc.;

7. Valves for rural and urban heating
In the urban heat generation system, a large number of metal-sealed butterfly valves, horizontal balance valves and direct-buried ball valves are needed, because these valves solve the problem of vertical and horizontal hydraulic imbalance of pipelines, and achieve the purpose of energy saving and heat balance.

8. Environmental protection valve
In the domestic environmental protection system, the water supply system mainly requires centerline butterfly valves, soft-sealed gate valves, ball valves, and exhaust valves (used to remove air in the pipeline). The sewage treatment system mainly needs soft sealing gate valve and butterfly valve;

9. Gas valve
City gas accounts for 22% of the entire natural market, with a large amount of valves and many types. Mainly need ball valve, plug valve, pressure reducing valve, safety valve;

10. Valves for pipeline applications
Long-distance pipelines are mainly crude oil, finished products and natural pipelines. The most commonly used valves for this type of pipeline are forged steel three-body full bore ball valves, anti-sulfur flat gate valves, safety valves, and check valves.

Valve material comparison table-valve pressure-temperature

The relationship between valve temperature and pressure:
The valve operating temperature and pressure have a certain internal connection and influence each other. Among them, temperature is the dominant factor affecting the valve. A valve with a certain pressure is only suitable for a

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

certain temperature range, and changes in valve temperature can affect the valve’s operating pressure. E.g:
The nominal pressure of a carbon steel valve is 10MPa. When the medium working temperature is 200℃, its maximum working pressure P20 is 10MPa; when the medium working temperature is 400℃, its maximum working pressure P40 is 5.4MPa; when the medium works When the temperature is 450℃, the maximum working pressure P20 is 4.5MPa.

Valve material temperature and pressure comparison table:
Valve material and applicable pressure, temperature and grade
Gray cast iron is suitable for water, steam, air, gas, oil and other media with nominal pressure PN≤1.0MPa and temperature -10℃~200℃. Commonly used grades are: HT200, HT250, HT300, HT350.
Malleable cast iron Suitable for water, steam, air and oil media with nominal pressure PN≤2.5MPa and temperature -30~300℃. Commonly used grades are: KTH300-06, KTH330-08, KTH350-10.
Nodular cast iron is suitable for water, steam, air and oil with PN≤4.0MPa and temperature of -30~350℃. Commonly used grades are: QT400-15, QT450-10, QT500-7. At present, the level of domestic technology varies among factories, and it is often difficult for users to inspect. It is recommended that PN≤2.5MPa, and steel valves are used for safety.
Acid-resistant high-silica ductile iron Suitable for nominal pressure PN≤0.25MPa, suitable for corrosive media with temperature lower than 120℃.
Carbon steel is suitable for water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with a nominal pressure of PN≤32.0MPa and a temperature of -30~425℃. Commonly used grades are WC1, WCB, ZG25, high-quality steel 20, 25, 30 and low-alloy structural steel 16Mn.
Copper alloy is suitable for water, sea water, oxygen, air, oil and other media with PN≤2.5MPa and steam media with temperature of -40~250℃. Commonly used grades are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (brass) , QAZ19-2, QA19-4 (aluminum bronze).
High-temperature copper is suitable for steam and petroleum products with nominal pressure PN≤17.0MPA and temperature≤570℃. The specific selection must be in accordance with the valve pressure and temperature specifications. Commonly used grades are ZGCr5Mo, 1Cr5M0.ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9, etc.
Low-temperature steel is suitable for media with nominal pressure PN≤6.4Mpa and temperature≥-196℃ ethylene, propylene, liquid natural gas, liquid nitrogen, etc. Commonly used grades are ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9
Stainless and acid-resistant steel Suitable for media such as nitric acid and acetic acid with nominal pressure PN≤6.4Mpa and temperature≤200℃. Commonly used grades are ZG0Cr18Ni9Ti, ZG0Cr18Ni10<nitric acid>, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti<acid and urea>

Valve seal (ring) material usage range comparison table

The selection of valve sealing material is determined according to the operating conditions of the valve, such as: pipeline medium, temperature range (high and low temperature), pressure and internal structure of the valve. For

soft sealing marine valve, rubber sealing, valve seat parts

soft sealing marine valve, rubber sealing, valve seat parts

different occasions, the selected seals are also different. Valve seals can generally be divided into two categories: soft seals and hard seals. Users should have a detailed understanding of their codes, operating temperature, pressure, medium and other parameters.

Comparison table of valve sealing material usage range:
Valve sealing material and valve sealing material use range:
Rubber (X) Nominal pressure PN ≤ 1 MPa, operating temperature t ≤ 150℃, applicable valves: globe valves, diaphragm valves, butterfly valves, check valves, etc.
Nylon (N) Nominal pressure PN ≤ 32 MPa, operating temperature t ≤ 90°C, applicable valves: globe valves, ball valves, etc.
PTFE (F) Nominal pressure PN ≤ 6.4 MPa, operating temperature t ≤ 180°C, applicable valves: globe valves, ball valves, gate valves, diaphragm valves, butterfly valves, check valves, etc.
Bus alloy (B) Nominal pressure PN ≤ 2.5 MPa, operating temperature t ≤ 150°C, applicable valves: stop valves for ammonia, etc.
Ceramic (G) Nominal pressure PN ≤ 1.6 MPa, operating temperature t ≤ 150°C, applicable valves: ball valves, plug valves, etc.
Enamel (C) Nominal pressure PN ≤ 1.0 MPa, operating temperature t ≤ 80°C, applicable valves: globe valve, diaphragm valve, check valve, discharge valve, etc.
Copper alloy (T) Nominal pressure PN ≤ 1.6 MPa, operating temperature t ≤ 200℃, applicable valves: gate valve, globe valve, check valve, plug valve, etc.
Stainless steel (H) Nominal pressure PN ≤ 32 MPa, operating temperature t ≤ 450°C, applicable valves: globe valves, ball valves (medium and high pressure valves), etc.
Nitrided steel (D) Nominal pressure PN ≤ 10 MPa, operating temperature t ≤ 540℃, applicable valves: power station gate valves, only for general use
Cemented carbide (Y) Nominal pressure (PN) and operating temperature (t) are determined according to the material of the valve body. Applicable valves: high pressure, ultra high pressure valves, high temperature and low temperature valves

What is the positive transmission of gears

When the total displacement coefficient of a pair of gears is greater than 0, it is a positive transmission.
Positive transmission refers to the positive displacement design of the gear. If two gears meshing with each other are in positive displacement, their center distance is greater than (the pair of gears) standard center distance. Conversely, if both gears use negative displacement, the center distance is smaller than the standard center distance. To judge whether the position is shifted, it is mainly to compare the measured gear parameters (including center distance) with the standard parameters of the gear to draw a conclusion.
Gear transmission is the most widely used transmission form in mechanical transmission. It has relatively

accurate transmission, high efficiency, compact structure, reliable work and long life. At present, the achievable indexes of gear technology: peripheral speed v=300m/s, rotation speed n=105r/min, transmitted power P=105KW, modulus m=0.004~100mm, diameter d=1mm~152.3mm
Features
1, the instantaneous transmission ratio is constant. The instantaneous transmission ratio of non-circular gear transmission can be designed according to the required change law.
2, the transmission ratio range is large, which can be used to decelerate or increase speed.
3, the range of speed (pitch circle speed) and transmission power is wide, and it can be used for high-speed (v>40m/s), medium-speed and low-speed (v<25m/s) transmission; power is from less than 1W to 105KW.
4, high transmission efficiency. A pair of high-precision involute cylindrical gears has an efficiency of over 99%.
5, compact structure, suitable for short-distance transmission.
6, the manufacturing cost is higher. Certain gears with special tooth shapes or high precision require special or high-precision machine tools, cutting tools and measuring instruments, so the manufacturing process is complicated and the cost is high.
7, low-precision gears, noise, vibration and shock during transmission, pollute the environment.
8, no overload protection
According to the relative position of the two shafts and the direction of the gear teeth, it can be divided into the following types:
<1>Straight tooth cylindrical gear drive;
<2> Helical cylindrical gear drive
<3> herringbone gear transmission;
<4> bevel gear transmission;

bevel gear

bevel gear

<5> cross-axis helical gear transmission.
According to the working conditions of the gear, it can be divided into:
<1>; Open gear transmission type gear transmission, the gears are exposed, and good lubrication cannot be guaranteed.
<2>; half-open gear transmission, the gear is immersed in the oil pool, with a protective cover, but not closed.
<3>; closed gear transmission, gears, shafts and bearings are all installed in a closed box, with good lubrication conditions, difficult for dust and sand to enter, accurate installation,
Gear transmission has good working conditions and is the most widely used gear transmission.
Gear transmission can be classified according to the relative position of its axis.
Gear drive can be divided into cylindrical gear drive, bevel gear drive, non-circular gear drive, rack drive and worm drive according to the shape of the gear.
According to the tooth profile curve, it can be divided into involute gear transmission, cycloid gear transmission and arc gear transmission. A transmission composed of more than two gears is called a gear train. The gear transmission can be divided into ordinary gear transmission and planetary gear transmission according to whether there are gears with axis movement in the gear train. The gears with axis movement in the gear train are called planetary gears. Gear transmission can be divided into closed type according to its working conditions
Gear transmission calculation
Open and semi-open transmission. Sealing the transmission in a rigid case and ensuring good lubrication is called closed transmission, which is more commonly used, especially for higher-speed gear transmissions, which must be closed transmission. Open transmission is exposed and cannot guarantee good lubrication. It is only used for low speed or unimportant transmission. Half-open transmission is somewhere in between.
The law of meshing:  The smoothness of gear transmission requires the instantaneous transmission ratio in the process of gear tooth meshing i=angular speed of driving wheel/angular speed of driven wheel=ω1/ω2=constant, this requirement is guaranteed by tooth profile. Figure 2 shows that the two meshing tooth profiles E1 and E2 are in contact at any point K, and the common normal line N1N2 of the two tooth profiles is made through the point K, which intersects the connecting center line O1O2 at point C. The condition for maintaining contact during the meshing process of the two tooth profiles is that the velocity of the K point on the tooth profile E1, vK1, and the K point velocity on the tooth profile E2, vK2, are equal in the direction of the common normal line N1N2, that is, vKn1=vKn2=vKn. Make perpendicular lines from O1 and O2 to the N1N2 line and intersect at points N1 and N2. The above formula shows that the two-wheel tooth profile must meet the following conditions: “No matter where the two-wheel tooth profile is in contact at any position, the common normal line passing through the contact point must pass the fixed point C ─ ─ node on the connecting center line.” This is a circular gear. The basic law of tooth profile meshing. There are many curves that can meet this law. In fact, the requirements of manufacturing, installation and load-bearing capacity should be considered. Generally, only involute, cycloid and arc are used as the working tooth profile of the gear. Part of the tooth profile is involute.
For involute gears, the base radius rb1 and rb2 of wheel 1 and wheel 2 in Fig. 2 are respectively. The N1N2 line is the internal common tangent of the two base circles, that is, the common normal of any contact point of the two tooth profiles coincides with it. Because the two base circles have only one internal common tangent in one direction, the common normal of any contact point passes through the fixed point C, which shows that using an involute as the tooth profile conforms to the basic law of tooth profile meshing.
The two circles drawn through node C with O1 and O2 as the centers are called pitch circles. The pitch radius of wheel 1 and the pitch radius of wheel 2 Involute gears have the following characteristics: ①N1N2 is the trajectory of the contact points of the two tooth profiles, called the meshing line, which is a straight line. ②The common tangent line tt of the two pitch circles of gear transmission through node C is called the meshing angle α’between it and the meshing line N1N2, which is a constant. ③The pressure between the tooth surfaces is always along the direction of the common normal line N1N2 of the contact point, so the pressure direction between the tooth surfaces does not change when the involute gear transmits power. ④The transmission ratio is inversely proportional to the radius of the base circle of the two wheels. After the gear is made, the base circle is determined. Therefore, even if the center distance is slightly deviated from the design during operation, the transmission ratio will not be affected. This feature is called the separability of the transmission. It affects the processing, assembly and Maintenance is very beneficial. ⑤The two tooth profiles only have no sliding between the tooth surfaces when the node C is in contact, and there is sliding between the tooth surfaces when they are in contact at other points, and the farther away from the node, the greater the sliding. ⑥Since the involute gear can mesh with a rack with a linear tooth profile, it can be processed by a tool with a linear tooth profile. The tool is easy to manufacture and the machining accuracy can be high.
Coincidence degree  Coincidence degree is an important parameter that affects the continuous transmission of gears. As shown in Figure 2, gear tooth meshing starts from the contact between the tooth root of the driving wheel and the tooth tip of the driven wheel, that is, the intersection A of the tooth tip circle of the driven wheel and the meshing line is the starting point of meshing. As the wheel 1 rotates, the wheel 2 is pushed to rotate, and the contact point moves along the meshing line. When the contact point moves to the intersection E of the addendum circle of the wheel 1 and the meshing line (the dotted line in the figure), the tooth profile When the meshing ends, the two tooth profiles begin to separate. Point E is the meshing end point, which is the actual meshing line length. If the front pair of teeth are still in contact at point D before point E, and the latter pair of teeth are in contact at point A, then the transmission is continuous; if the front pair of teeth has left at point E, and the latter pair has not yet entered meshing , Then the transmission is interrupted. Considering the influence of gear manufacturing, installation errors and deformation, ε≥1.1~1.4 is often required in practice. The greater the coincidence degree, the more stable the transmission. The above refers to the coincidence degree of the end face of the cylindrical gear, and there is a longitudinal coincidence degree for the helical cylindrical gear.
The condition for a pair of gears to be able to mesh correctly is that they must have equal modulus and equal pressure angle.

Accuracy requirements of Equipment installation

1. For static equipment
The vertical deviation of vertical equipment should not be greater than L/1000 and not greater than 10mm. Unless the drawings have special requirements.

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

The horizontal deviation of horizontal equipment should not be greater than L/1000 in the axial direction and 2D/1000 in the radial direction.

2. For moving equipment
When the pump is aligned, the selection of the installation datum and the allowable deviation of the level must meet the requirements of the “special specification” or the pump technical file. Generally, the allowable deviation of horizontal horizontality is 0.10mm/m, and the allowable deviation of vertical horizontality of the installation datum part is 0.05mm/m. The leveling and alignment values ​​must not be adjusted by loosening the anchor bolts.
1. The pump that is disassembled and installed is based on the processing surface of the pump body, and the allowable deviation of the horizontality of the pump in the vertical and horizontal directions is 0.05mm/m.
2. The integrally installed pump should be leveled based on the inlet and outlet flange surface or other horizontal processing datum plane. The allowable deviation of horizontality is 0.05mm/m in the longitudinal direction and 0.10mm/m in the transverse direction.
3. When the driving shaft and the driven shaft are connected by a coupling, the centering deviation of the two shafts and the gap between the end faces of the two shafts should be:
Centering deviation: the radial displacement is not more than 0.03mm.
The axial tilt should not be greater than 0.05/1000.
The end face gap is 1.00~3.5mm.

What is assembly error and how to control it?

Assembly error refers to the difference between the installation position of the parts and the ideal position required by the assembly specifications and design regulations and processes.

Causes of assembly errors:

Double flange butterfly valve (1)

Double flange butterfly valve (1)

①Part error: the additional error caused by the manufacturing error of the part and the deformation and wear after operation and use.
② Errors in tools and measuring tools: tools and quantities have manufacturing errors, and system errors will occur if they are used for measurement and positioning.
③Operation error: due to hand feeling (such as tightness, flatness, sharpness, smoothness, beating, shaking, vibration, spacing, pulling force, hand tapping, hand-hand gap, hand feeling loose, etc.), visual inspection (size, level, straight , Vertical, parallel, aligned, tangent, etc.), ear hearing (various abnormal noises), nose smell (leakage, etc.), the error generated by the human sensory identification.
④Environmental errors: errors caused by temperature, relative humidity, light direction, air flow direction, movement of the foundation, etc.
⑤ Consciousness error: error caused by lack of concentration or lack of responsibility.
How to control assembly error:
1. Choose a reasonable assembly benchmark
In order to make the assembly position of the part accurate, select a certain part (point, line, surface) of the already positioned part as the positioning basis for the part to be installed. This part is called the assembly datum. The correct choice of assembly benchmark is an important factor in improving assembly accuracy and reducing assembly errors, and must be taken seriously. The following factors should generally be considered for the correct selection of the assembly datum.
(1) Try to choose parts with higher machining accuracy, that is, parts with small dimensional tolerance, high shape accuracy, small position deviation, and low roughness as the reference. For example, the diameter tolerance and radial runout of the groove part during the manufacturing of the roller are lower than those of the smooth surface. Therefore, when checking the roller bending and correcting the roller gauge, the groove part is the reference.
(2) The reference position should be as close as possible to the assembly adjustment point. For example, when the car surface is flat, the height of the car surface should be adjusted by the frame lifting screw, so the flat ruler should be placed as close to the frame as possible. For example, if the flat-foot iron rest is placed far away from the frame, and the reference point is far away from the frame, when the height of the adjacent frame is adjusted, the iron rest will be driven to rise and fall to make the reference drift. As shown in Figure 1, suppose the center distance ab of the two frames is 1008mm, point a is the point where the top surface of the car has been leveled, and point b is the point where the top surface of the car is to be leveled. The flat ruler should be placed at point a. If it is not placed at point a, it should be placed at point d, 100mm (ad) away from point a. When correcting the length of the car to be horizontal, the car surface at the adjustment point is from point b Adjusted to point c, increased by 0.10mm (bc), this flat ruler bar was also driven to rise from point d to point e, rising by 0.01mm (de), that is, the benchmark is raised by 0.01mm.
This shows that the farther the flat-foot rail is from the frame, the greater the change in the height of the reference plane, which affects the assembly accuracy.
(3) Try to reuse the same datum as much as possible to eliminate the deviation of the part surface shape. For example, because the top surface has a certain degree of lengthwise bending and widthwise distortion, it is necessary to look at the length of the car surface to the level of the flat ruler, the level to look at the width of the car surface and the level of the front roller to support the height line. Line round rollers are placed in the same position to avoid additional errors caused by uneven top surface of the car.
(4) When selecting the benchmark, the convenience of flat mounting operation should also be considered. For example, there are generally two methods for positioning the helical gear of the spindle shaft: one is to insert the spindle, and use the spindle as the reference, and use the card board to locate; the other is to not insert the spindle, and the lower dragon-jin oil cup is the reference. Although the tolerance of the spindle diameter is smaller than the tolerance of the oil cup hole, it is more difficult to locate after inserting the spindle. Taking the oil cup hole as the reference, it can meet the left and right positioning requirements of the spindle gear, and the spindle can not be inserted, which makes the operation convenient.
(5) Try to be consistent with the reference parts of the machine manufacturer’s parts processing and pre-assembly.
2. Avoid multiple transmissions of assembly standards (reduce cumulative errors)
There are two ways to divide a 1m long straight line into ten equal parts: one is to use a 150mm steel ruler, and the steel ruler is moved every 1oomm for ten times; the other is to use 1m steel The ruler does not move, but takes ten points in sequence according to the corresponding scale line. It is obvious that the error of the second method is relatively small. Because of the former method, due to multiple movements of the measurement reference, two or more assembly errors (tools, operating errors) are superimposed together, and cumulative errors are generated. By the same token, when measuring the gap with a feeler gauge of specified degree, a single-page feeler gauge should be used as much as possible to measure more accurately, and avoid using two or more thin feeler gauges to measure.
3, master the law of change of error (eliminate system error)
If the variation law of the error is found and the value is ascertained, it is like trying to eliminate the error value during assembly. This kind of regular error is called systematic error. For example, when the inner diameter measuring claw of a vernier caliper wears out 0.02mm, making the reading of each measurement imaginaryly larger by 0.02mm, you can automatically subtract 0.02mm from the reading to get the actual reading you need. Another example is when the level of the bubble is inaccurate, after the positioning and U-turn inspection, it is found that the bubble is inaccurate. After positioning to a certain end, it is horizontal. Therefore, when looking at the level, you should deliberately make the main bubble to a certain end. , So that the parts reach a level state.
4. Reasonable allocation or adjustment error value (reduce assembly error)
1). Mutual loan
When large castings such as the drawing locomotive face, bottom plate, roving frame head and tail wall panels, frame, and face are twisted and deformed, due to the inconvenience of orthopedics, only the verticality or levelness of multiple points can be checked to make the readings positive and negative after flat mounting The maximum value of the direction is equal, or the difference after subtracting the maximum value of the positive and negative directions is not greater than the allowable error. This method is called the mutual loan method.
2). Adjustment method
When the cumulative error in assembly exceeds the allowable error, the size, shape or shape of one of the links can be changed, or an unimportant size can be discarded without control, so that the total size is within the allowable range. This changeable link is called the “adjustment ring”. For example, when adjusting the draw frame roller seat to open the gear, first determine the left and right positions of the upper wall panel from the outer line of the front of the car, and then set the first roller seat position based on the upper wall panel of the front of the car. Set the position of the second, third, and fourth roller seat in turn, and the size between the fourth roller seat and the upper wall panel of the car can only be abandoned, and it is impossible to correct it. In actual work, the size, shape or position of the adjustment ring Changes are often achieved by filing, padding, welding, or adjusting with adjustable parts, such as adjusting screws, adjusting washers, and foot pads. Using these parts to adjust can improve assembly accuracy and save manual work. File repair and other work.
3). Select right assembly method
In order to reduce assembly errors and improve the accuracy of parts assembly, parts with certain errors can also be matched or grouped through selection, so that the upper and lower errors between the parts can be matched to appropriately improve the accuracy, which is called selective assembly. For example, group the rubber roller core and the iron shell to make the gap consistent; divide the diameter of the rubber roller into several gears to make the diameter of the rubber roller of the same machine or the same zone be the same.

What is the transmission ratio

In a mechanical transmission system, the ratio of the angular velocity or rotational speed of the driving wheel at the beginning and the driven wheel at the end.
Transmission ratio (i) = ratio of driving wheel speed (n1) to driven wheel speed (n2) = inverse ratio of gear index circle diameter = ratio of driven gear teeth (Z2) to driving gear teeth (Z1).
That is: i=n1/n2=D2/D1 i=n1/n2=z2/z1
For multi-stage gear transmission
1: The transmission ratio between every two shafts is calculated according to the above formula
2: The total transmission ratio from the first axis to the nth axis is calculated according to the following formula: Total transmission ratio ι=(Z2/Z1)×(Z4/Z3)×(Z6/Z5)……=(n1/n2)× (N3/n4)×(n5/n6)……

For multi-stage gear transmission

For multi-stage gear transmission

Extended information

The ratio of the angular velocities of the two rotating components in the mechanism is also called the speed ratio. The transmission ratio of component a and component b is Ⅰ=ωa/ωb=na/nb, where ωa and ωb are the angular velocities (radians/sec) of components a and b, respectively; na and nb are the rotational speeds of components a and b respectively ( Rpm) (Note: a and b after ω and n are subscripts).
When the angular velocity in the formula is an instantaneous value, the obtained transmission ratio is the instantaneous transmission ratio. When the angular velocity in the formula is an average value, the obtained transmission ratio is the average transmission ratio. For most gear transmissions and friction wheel transmissions with the correct tooth profile, the instantaneous transmission ratio is unchanged; for chain transmission and non-circular gear transmission, the instantaneous transmission ratio is variable.
For meshing transmission, the transmission ratio can be expressed by the number of teeth Za and Zb of wheel a and wheel b, i=Zb/Za; for friction transmission, the transmission ratio can be expressed by the radius Ra and Rb of wheel a and wheel b, i=Rb/Ra, At this time, the transmission ratio generally means the average transmission ratio.
In hydraulic transmission, the transmission ratio of the hydraulic transmission element generally refers to the ratio of the turbine speed S and the pump wheel speed B, that is, =S/B. Hydraulic transmission elements can also be combined with mechanical transmission elements (generally with various gear trains) to obtain various transmission ratios of different values ​​(see gear trains for gear train transmission ratios).

Check valve model designation method

Check valve model representation method  Check model preparation instructions
Check valve (one-way valve) model compilation instructions:
Check valve (one-way valve) is also called check valve or reverse flow valve. It is an automatic valve that opens or

tilting disc swing check valve (3)

tilting disc swing check valve (3)

closes the disc through the flow of the medium itself, and can only flow in one direction and cannot be reversed. It is mainly used for In the piping system, prevent the medium from flowing back or flowing backward. Check valves have a wide range of uses and types. Different types of check valves are also different in different pipelines, operating conditions and connection methods. In order to avoid selecting the wrong model when purchasing a valve, and causing unnecessary working conditions during the application process due to improper model selection, users should have more understanding and awareness of the following check valve model preparation instructions. Check valve (check valve) model compilation instructions are mainly to make a detailed analysis of the additional conditions, connection methods, structural forms, sealing materials, pressure ratings and shell materials of the check valve. Hope it helps you when you buy check valves.

Check valve (check valve) model representation method:
Additional code of check valve: HH: micro-resistance slow-closing check valve, BH: heat preservation check valve, HQ: rolling ball check valve;
Check valve code: H stands for check valve;
Connection code: 4 flanges, 6 welding, 7 wafer;
Code of structural form: 1: lift type, 2: vertical type, 4: swing type, 6: double flap type, 8: butterfly type;
Sealing material code: B: babbitt alloy, F: fluorine plastic, H: stainless steel, M: Monel alloy, X: rubber, Y: cemented carbide, W: direct processing;
Pressure grade code: 16=16 kg pressure, PN1.6-25mpa, pound grade 150LB-2500LB, Japanese grade 5K-63K;
Shell material code: Q: ductile iron, C: carbon steel, P:304, R:316, A: titanium alloy, I: chromium molybdenum steel;

Example of model preparation of check valve (check valve):
H44H-16C swing flange check valve
H: indicates the check valve;
4: Flange link;
4: Swing type;
H: The sealing material is stainless steel;
16: The pressure is 16 kg (1.6mpa)
C: The valve body is carbon steel.