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Chatter

What Is Chatter?

A Chatter in the machine tool industry refers to abnormal vibrations during cutting and grinding, leading to chatter marks on the machined surface and potential damage to tools and machinery.

Types of Chatter

There are two main types of chatter vibrations:

  • Self-Excited Chatter: Also known as regenerative chatter, it arises from periodic fluctuations on the newly machined surface or multiple vibration modes. This type often leads to a progressive increase in machining irregularities and periodic vibrations.
  • Forced Chatter: Caused by internal or external vibrations impacting the machined surface, leading to significant machining irregularities.

Principles and Control of Chatter

The control methods for chatter depend on its cause:

  • Self-Excited Chatter: Control strategies focus on system vibration response, influenced by cutting conditions, tool geometry, and machine dynamics. Solutions include modifying cutting speed, depth of cut, spindle speed, tool design, and enhancing machine rigidity. Tool improvements might involve using spring tooling or dampers.
  • Forced Chatter: For internal vibrations, solutions include isolating vibration sources, using flexible couplings, and adjusting rotational speeds. External vibrations can be mitigated through anti-vibration foundations or rubber mounts. Fluctuations in cutting force can be managed by altering tool shape, cutter blade count, or using unequal pitch cutters.
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PC Steel Wire

What Is PC Steel Wire?

PC Steel WiresPC steel wire is a high-strength wire used in prestressed concrete to enhance the tension properties of concrete, which is typically weak in tension. By applying compressive force during manufacturing, it significantly increases the structure’s strength, clamping concrete at high stresses of about 80% of the yield point.

Key quality parameters include high tensile strength, elongation at break, low relaxation, straightness, workability, and uniformity.

Uses of PC Steel Wires

PC steel wires, with a strength of 5 to 6 times that of regular steel bars, are used for pre-stressing concrete through pre-tensioning or post-tensioning methods. Their applications span across:

  • Road and rail bridges, sleepers, tanks, and construction
  • Bridge structures, building foundations, and bodies
  • Containers like tanks and reservoirs
  • Disaster prevention equipment like rock-sheds and snow-sheds
  • Cores for telegraph poles

Special cutting machines are used for PC steel wires in emergencies.

Types of PC Steel Wires

PC steel wires are categorized based on strength and shape:

  • Normal strength types: SWPR1AN, SWPR1AL, SWPD1N, SWPD1L
  • High strength types: SWPR1BN, SWPR1BL
  • Shapes include round wire and irregularly shaped wire. Round wires are classified as Class A or B (Class B being stronger), and deformed wires as SWPR1BN or SWPR1BL, with ‘N’ for normal relaxation and ‘L’ for low relaxation.

Standards specify nominal dimensions, cross-sectional area, mass, stress and force tests, elongation, relaxation values, and strength levels. Winding, torsional, and bending properties are also outlined.

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PC Steel Bar

What Is a PC Steel Bar?

A PC (Prestressed Concrete) steel bar is a high-strength steel bar used in pre-stressed concrete to enhance its tensile strength. These bars are pre-tensioned to apply compressive force to concrete, increasing the overall strength of the structure. They are typically stressed to about 80% of their yield point.

In manufacturing, the steel is drawn into wires, heat-treated for required mechanical properties, cut to specified lengths, and subjected to thread rolling. Chemical composition typically focuses on three elements: phosphorus (P), sulfur (S), and copper (Cu).

Uses of PC Steel Bars

PC steel bars are extensively used in construction for various applications including:

  • Foundation piles for buildings and power transmission towers
  • Concrete poles for communication towers
  • Concrete sleepers for railways
  • Piles for sewage systems, culverts, and bridges

They come in both fully threaded and end-threaded variants, with the former often used as ground anchors or in temporary construction materials.

Types of PC Steel Bars

There are two main shapes: deformed round steel SBBR and deformed PC bar SBPD, classified into three strength classes (A, B, C). Standard sizes range from φ9.2 mm to φ32 mm for deformed round steel bars and φ7.4 mm to φ13 mm for deformed PC bars. Key mechanical properties include load, tensile strength, elongation, and relaxation values for 0.2% permanent elongation.

PC steel bars are manufactured as rolled bars (stretched and blued), heat-treated bars (quenched and tempered, sometimes drawn before heat treatment), and drawn bars (drawn and blued). Exposure to sudden temperature changes, like fire or welding, can significantly reduce their strength and toughness.

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Steel I-Beam

What Is a Steel I-Beam?

Steel I BeamsA steel I-beam is a long steel beam with an H-shaped cross-section, mainly used as columns and beams in steel-framed buildings. The manufacturing of steel shapes by hot rolling was first patented in 1849 by a Belgian company.

Uses of Steel I-Beams

Steel I-beams are favored for their high compression and bending resistance. They are commonly used in:

  • Foundation piles for quays, buildings, bridges, etc.
  • Structures of high-rise buildings
  • Crane girders for overhead cranes
  • Steel stairs in industrial settings

There are two main types of steel I-beams: one for structural purposes and another for foundation columns.

Principles of Steel I-Beams

Steel I-beams are made from either rolled structural steel (SS) or welded structural steel (SM), with rolled structural steel (SN) specifically used in building construction since 1994. SS material is typically used for secondary members, SM for welded beams, and SN for large beams in architecture.

Steel I-beams offer high bending resistance per unit weight, which can be increased by thickening the flanges.

Types of Steel I-Beams

  • Rolled Steel I-Beams: Formed by rolling iron into an H shape, suitable for mass production.
  • Built Steel I-Beams: Made by welding steel plates into an H shape, allowing for custom thickness and dimensions but more expensive than rolling.
  • External Constant Steel I-Beams: Feature a constant width from top to bottom, used for beams with large spans.

Manufacturing Process of Steel I-Beams

The hot rolling process involves initially rough rolling a heated steel ingot (bloom) with grooved rolls to form a shape similar to steel I-beams. The material is then rolled into the I-beam shape using a universal rolling mill. Recent advancements allow for easier adjustments in the web height and flange width without changing the rolls. In some cases, the steel ingot process is bypassed, and slabs from the continuous casting method are directly used in rolling.

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Boron Steel

What Is Boron Steel?

Boron steel (B steel) is a type of carbon steel enhanced with boron and chromium. Boron, typically added in about 0.0008%, is effective in improving the steel’s hardenability, while chromium is added in the range of 0.10 to 0.20%. This steel also includes adjustments of other elements such as copper and nickel. In alloy boron steel, the chromium content is higher.

Uses of Boron Steel

Boron steel is commonly used in automotive parts, especially in bolts and nuts, and serves as a general-purpose alternative to alloy steel for applications where extreme strength isn’t necessary. It is suitable for bolt strength classifications up to 10.9. The inclusion of boron allows for the omission of the heat treatment process in wire rod processing, simplifying manufacturing steps like cold forging.

Types of Boron Steel

Boron steel comes in various forms, including carbon boron steel, manganese boron steel, and alloy boron steel, as specified by the SAE (U.S.) standard. For instance, 1021B indicates boron steel with the ‘B’ signifying boron addition.

Different types of boron steel are used to eliminate or reduce heat treatment requirements in parts manufacturing. Examples include hardened boron steel for gear parts, bolt boron steel for bolts, and low-Mo tough boron steel for knuckle parts. High-strength, high-toughness boron steel is used in link applications. When used in high-strength bolts, it’s important to choose a type designed for delayed fracture resistance to prevent brittle fracture from hydrogen embrittlement.

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réchauffeur

Qu’est-ce qu’un réchauffeur ?

Un réchauffeur est un terme utilisé pour décrire tous les appareils qui génèrent de la chaleur.

Le type d’appareil qui brûle du combustible pour générer une chaleur rayonnante est peu coûteux et est donc largement utilisé dans les appareils ménagers. Il s’agit également d’un équipement essentiel dans l’industrie, pour la transformation et l’assemblage.

Utilisations des réchauffeurs

Les réchauffeurs sont des appareils utilisés dans un large éventail d’utilisations, des appareils ménagers à l’industrie. Voici quelques exemples :

1. Réchauffeurs de panneaux

Dans les régions froides où les températures sont inférieures à zéro, il n’est pas rare que les composants internes des panneaux de contrôle se condensent ou gèlent. Il peut s’avérer nécessaire de maintenir la température interne constante à l’aide de réchauffeurs de panneaux. Les réchauffeurs sont également synonymes et sont souvent installés à l’intérieur des générateurs et autres équipements.

2. Réchauffeurs de plomberie

Ces réchauffeurs sont utilisés pour empêcher le gel des conduites d’eau, etc. Ils sont également appelés réchauffeurs antigel, ceintures antigel ou réchauffeurs de trace. Les réchauffeurs à bande et à courroie sont principalement utilisés.

3. Réchauffeurs industriels

Ces réchauffeurs sont utilisés pour chauffer des matières premières et des produits à des fins industrielles. Les principes utilisés varient et les réchauffeurs sans contact tels que le chauffage par induction et le chauffage diélectrique sont également utilisés.

Les utilisations sont variées et comprennent les réchauffeurs de roulements pour l’enlèvement des roulements dans les équipements rotatifs. Les extrudeuses et les machines de moulage utilisent des réchauffeurs de coulée, par exemple.

4. Réchauffeurs domestiques

Il s’agit de réchauffeurs utilisés pour le chauffage et à d’autres fins dans la maison. Les climatiseurs et les aérothermes en sont des exemples typiques. Les appareils de chauffage en céramique sont parfois utilisés. Les fours à micro-ondes et les grille-pain pour la cuisine sont également des types de réchauffeurs.

Principe des réchauffeurs

Les réchauffeurs chauffent des objets selon différents principes. Voici quelques exemples de principes de chauffage des réchauffeurs :

1. Chauffage par résistance

Le chauffage par résistance est une méthode qui consiste à faire passer un courant électrique à travers une résistance pour générer de la chaleur par effet Joule. Un fil de nichrome est utilisé comme élément chauffant. L’élément chauffant est placé dans une gaine métallique, telle qu’un tuyau, entre laquelle se trouve souvent un isolant.

2. Chauffage par induction

Cette méthode permet de chauffer un objet en générant et en modifiant le flux magnétique au moyen d’une bobine, générant ainsi des courants de Foucault. Parmi les utilisations typiques, l’on peut citer les réchauffeurs à induction pour la cuisine. Le chauffage sans contact est possible, mais l’objet à chauffer est principalement constitué de matériaux conducteurs.

3. Chauffage diélectrique

Il s’agit d’une méthode de chauffage par application d’une tension à haute fréquence, qui agite les molécules et génère de la chaleur par friction. Les fours à micro-ondes sont un exemple d’utilisation du chauffage diélectrique. Le chauffage sans contact est possible et est utilisé pour chauffer des matériaux non conducteurs.

4. Pompe à chaleur

Méthode de chauffage par échange de chaleur avec une source de chaleur. Les climatiseurs et les chauffe-eau en sont des exemples typiques. Les climatiseurs, par exemple, ajoutent de la chaleur à une pièce en chauffant l’échangeur de chaleur intérieur avec la chaleur de condensation du réfrigérant comprimé.

Types de réchauffeurs

Il existe différents types de réchauffeurs, classés en fonction de la cause de la production de chaleur et de l’application. Ils sont également classés en fonction de la méthode de conduction de la chaleur. Les méthodes de chauffage basées sur la résistance comprennent la convection, la conduction et le rayonnement.

1. Réchauffeurs à convection

Cette méthode consiste à chauffer l’air directement et à le faire circuler. Elle présente certains inconvénients, tels que l’assèchement et l’empoussièrement de l’air chaud. Elle se caractérise toutefois par une chaleur immédiate. Il existe des réchauffeurs à ventilateur à huile et des réchauffeurs à ventilateur en céramique.

2. Réchauffeurs par conduction

Cette méthode transfère la chaleur par contact direct. Seule la zone de contact peut être réchauffée. Elle se caractérise par une consommation d’énergie plus faible que la méthode de convection. Des tapis chauds et des couvertures électriques sont disponibles.

3. Réchauffeurs par rayonnement

Cette méthode chauffe en émettant des rayons infrarouges et de la chaleur, qui sont des ondes électromagnétiques. Elle se caractérise par une chaleur qui provient de l’air et est silencieuse. Il existe des réchauffeurs à charbon et des réchauffeurs à huile.

Autres informations sur les réchauffeurs

Technologie d’économie d’énergie pour les réchauffeurs

Il est possible d’économiser de l’énergie en contrôlant la consommation d’énergie des réchauffeurs et en les utilisant efficacement. En général, les techniques d’économie d’énergie consistent à utiliser des plaques d’isolation thermique et des matériaux d’isolation thermique pour maintenir la chaleur à l’extérieur. Dans certains cas, le contrôle de la température au moyen d’un contrôle de la tension, par exemple, peut contribuer aux économies d’énergie.

Un contrôle avancé de la température contribue également à améliorer les conditions de travail et la précision du traitement des produits. Si la cible chauffée est un liquide tel que l’eau ou l’huile, le contrôle de la température est nécessaire en fonction des caractéristiques du liquide et de la température cible. Lors du chauffage de solides, le contrôle de la température est un facteur de qualité important.

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Rolled Structural Steel

What Is Rolled Structural Steel?

Rolled Structural SteelRolled structural steel, commonly designated as SM400B or SM490C, is a type of steel material initially developed for shipbuilding. The ‘SM’ stands for ‘steel marine,’ with the numerical values indicating the minimum guaranteed tensile strength and the letters A, B, and C representing different grades, with C being the highest.

There are 11 types of rolled structural steel for welded structures, categorized based on yield point, tensile strength, and chemical composition.

Uses of Rolled Structural Steel

Primarily used for welded components, this steel was initially predominant in ship hulls. Its applications have since expanded to include architecture, social infrastructure, pipelines, industrial machinery, and power generation plants.

Characteristics of Rolled Structural Steel

The range includes SM400A, SM400B, SM400C, SM490A, SM490B, SM490C, SM490YA, SM490YB, SM520B, SM520C, and SM570. While similar in additive composition to general structural steel (SS material), rolled structural steel is made from killed steel, which is deoxidized with substances like silicon or aluminum to enhance toughness at low temperatures. This makes it suitable for use in temperatures from 14°F to 660°F.

Grades B and C are impact-tested steels with guaranteed low-temperature toughness, while Class A offers weather resistance and strength. Class Y is specifically designed for higher yield points, making it ideal for long-term use in bridges and civil engineering applications.

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Carbon Steel for Machine Structural Use

What Is Carbon Steel for Machine Structural Use?

Carbon Steel for Machine Structural UseCarbon Steel for Machine Structural Use, commonly known as SC material (Steel-Carbon), is extensively used for machine parts, automobile transmissions, bolts, nuts, drill chucks, wrench tools, and more.

Spanning 23 types from S10C to S58C, the carbon content is indicated by the middle number, multiplied by 100%. Higher carbon content results in greater strength but reduced toughness. For instance, S30C is a popular choice, offering lower hardness and ease of machining compared to alloy steels.

Uses of Carbon Steel for Machine Structural Use

SC material is ideal for parts requiring machining before heat treatment. It’s widely used in mechanical components like pulleys, brackets, gears, and tools. However, due to changes in properties with heat, it’s not suitable for heat-intensive welding processes.

Types of Carbon Steel for Machine Structural Use

SC steel has a carbon content ranging from 0.08 to 0.6%. Steels with higher carbon content are classified as SK steel. S30C and above are generally used for high-strength parts. SC material has a pearlite and ferrite metallic structure at room temperature, with the pearlite proportion increasing with carbon content. The metallographic structure, particularly the percentage of pearlite, can indicate the carbon content of the steel.

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Rolled Steel

What Is Rolled Steel?

Rolled SteelRolled steel is a steel material formed into sheets through a rolling process involving multiple rolls. It’s cost-effective and well-suited for bending, pressing, and sheet metal working, often used in exteriors and coverings where mechanical strength is not a primary requirement.

Rolled steel is categorized into hot rolled steel (SPHC) and cold rolled steel (SPCC), based on the temperature at which it’s rolled.

Uses of Rolled Steel

Rolled steel varies in application, including general structure (SS), building structure (SN), and welded structure (SM) types. It’s commonly used in building structures, particularly in main columns, beams, and welded components due to its high plastic deformation capacity and excellent weldability.

Characteristics of Rolled Steel

Hot-rolled steel, made by heating and rolling the metal at high temperatures (1800 to 2100°F), offers benefits like easier rolling and stronger crystal structures. However, it may have downsides like oxide film formation and loss of dimensional accuracy.

Cold-rolled steel, processed at room temperature, is known for its smooth surface and high dimensional accuracy but requires more force for processing and may undergo work hardening.

Additionally, “warm rolling” is a lesser-known method that serves as an intermediate process between cold and hot rolling.

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Carbon Steel Tube

What Is a Carbon Steel Tube?

Carbon Steel TubesCarbon steel tubes are steel materials used for various structural purposes in civil engineering and building construction. They are known for their earthquake resistance, high strength, and corrosion resistance and are identified with the symbol “STK”.

Uses of Carbon Steel Tubes

Carbon steel tubes are widely used in construction and civil engineering for frames, pillars, piles, landslide prevention piles, steel towers, scaffolding, and agricultural machinery. They must comply with strength regulations specific to their application, with diameters ranging from 21.7 mm to 1016.0 mm.

Types of Carbon Steel Tubes

Classification of Carbon Steel Tubes

Carbon steel tubes are categorized into five types based on their chemical composition and mechanical properties: STK290, STK400, STK490, STK500, and STK540.

  • STK290: Used for light structural members due to its lowest tensile strength.
  • STK400: General structure steel pipe, complying with Building Structure Calculation Standards.
  • STK490: High-tensile strength steel pipe for welded structures.
  • STK500: High carbon content steel pipe, mainly used for scaffolding.
  • STK540: Highest tensile strength steel pipe, important for weldability.

Classification by Manufacturing and Finishing Method

  • Specified Manufacturing Method: Seamless, electric resistance welding, forge welding, and automatic arc welding.
  • Specified Finishing Methods: Hot finishing, cold finishing, electric resistance welded as welded.