月: 2024年1月

What Is a Helical Gear?

A gear is a toothed wheel designed to transmit torque through meshing with other gears. Helical gears, a common type of gear, have teeth cut at an angle, forming a helix.

Unlike spur gears that only transmit power with parallel axes, helical gears can also operate with intersecting axes. Their teeth are arranged diagonally, allowing for smoother meshing and continuous contact between teeth. This design reduces noise and vibration during operation but makes the manufacturing process more complex.

Uses of Helical Gears

Helical gears are widely used in several industries due to their efficiency and smooth operation:

1. Automobiles

In automobile gearboxes, helical gears transmit power from the engine to the wheels. They facilitate different gear ratios for various speed ranges, contributing to smooth gear changes and quiet operation.

2. Industrial Machinery

These gears are integral to many industrial machines, driving conveyor belts, and axis drives in CNC machines, ensuring precision and reliability.

3. Aircraft

Helical gears in aircraft transmit power in engine mechanisms and control systems, ensuring efficient motion transfer to propellers or fans and reliable operation in control systems.

4. Generators

Used in generators and turbines, helical gears transfer high-speed rotational power, playing a crucial role in effective power generation.

Principle of Helical Gears

Helical gears work by meshing teeth cut in a helical pattern, providing a high meshing ratio for smooth and continuous engagement. The progressive contact of the teeth distributes force evenly, reducing sudden stress and ensuring smoother power transmission.

The helical design creates thrust forces during rotation, necessitating robust bearings to withstand these forces. Angular contact bearings are common, but thrust bearings may be used for heavy loads.

Choosing Helical Gears

The helix of helical gears can be either right-handed or left-handed. The selection depends on the alignment of the input and output shafts. For parallel shafts, gears with the same helix direction are used, while intersecting or helically aligned shafts require opposite helix directions.

The helical angle, representing the axial advance per revolution, is crucial. A larger helical angle results in smoother gear meshing and quieter operation. Careful consideration of the rotation direction and helical angle is essential to ensure efficient power transmission and gear longevity.

What Is a Power Breaker?

A power breaker, commonly referred to simply as a breaker, is an essential component in electrical systems. It is used to connect power lines to electrical machinery, typically through a power distribution or control panel. The connection from the breaker to the machinery is often made using components like electromagnetic contactors.

Power breakers are vital not only in industrial settings but also in residential environments.

Uses of Power Breakers

Power breakers are crucial for protecting equipment and preventing fires by interrupting the power supply in cases of overcurrent. This function is essential when connecting devices like plugs or operating power-driven machinery.

There are two main types of power breakers: wiring breakers and leakage breakers. Wiring breakers, also known as safety breakers, cut off the power supply when the current exceeds a set limit. Leakage breakers perform a similar function but also detect and interrupt power leakage from equipment or wiring.

Principle of Power Breakers

The capacity of a breaker is indicated by its Ampere Frame (AF), which also determines the size and interrupting capacity. The rated current is represented by Ampere Trip (AT), denoting the current level at which the breaker will trip. AF indicates the maximum current a breaker can handle, while AT specifies the tripping threshold.

Breakers can trip based on three different mechanisms. The first is thermal-magnetic, utilizing a bimetal strip that bends when heated by overcurrent, triggering a trip. The second is electromagnetic, where an electromagnetic force generated by overcurrent overcomes a spring, causing the breaker to trip. The third type is electronic, employing circuitry to detect overcurrent and activate the tripping mechanism.

What Is a Simple Cart?

A simple cart is a versatile tool for storing, displaying, and transporting goods. This term encompasses various vehicles and structures like carts, wagons, racks, and cargo carriers.

Carts are designed for item transportation and are often foldable for convenient storage. Wagons, available in multiple sizes, are suitable for carrying a range of item sizes and can be used for both transportation and product display. Racks typically feature a mesh or wire structure, while cargo carriers are ideal for moving large or bulk items.

Uses of Simple Carts

Simple carts, including cargo carriers, are widely used for transporting large items. These carts can be easily loaded onto trucks for transport. Available in various sizes, they cater to both commercial and personal needs. Lightweight carts are particularly useful for everyday tasks like grocery shopping or transporting heavy items like beverage cases.

In shopping centers, carts are often two-tiered to securely hold baskets and prevent them from tipping over. Some models also include features for safely carrying small children.

Principle of Simple Carts

The design of simple carts focuses on efficient transportation of goods. Many feature casters for easy movement and are constructed with high-strength materials for durability. Shopping carts are specifically designed to hold a standard 33 L basket and often have minimal structural elements to maximize strength and basket capacity.

Household carts emphasize storage convenience and are frequently foldable for space-saving storage. To protect fragile items during transport, these carts often have casters made of shock-absorbing materials like rubber. Household racks come in various sizes, from compact models for specific spaces to adjustable designs for customizable storage solutions.

What Is a Shunt Resistor?

A shunt resistor is a component used to measure current in an electrical circuit.

The term “shunt” implies meanings such as “diverting” or “sidetracking,” leading to its alternative name, “current shunt.” This component is primarily used for current verification, battery level detection, and similar applications. It offers a reliable method for measuring electric current.

As current passes through the shunt resistor, its resistance value and the voltage drop across it are used to accurately determine the current. A notable feature of shunt resistors is their applicability in high-current situations.

In high-current circuits, where wires are often thick, traditional clamp-type current measurement methods can be challenging. Using a low-resistance shunt resistor, accurate and reliable current readings can be obtained. However, in high-current circuits, shunt resistors may generate significant heat, necessitating cooling solutions.

Uses of Shunt Resistors

Shunt resistors are utilized in various electrical circuit applications, as outlined below:

1. Instrumentation Wiring

Commonly, shunt resistors have a resistance value of 250Ω. The DC4-20mA current signal is a standard analog output signal, less affected by a voltage drop due to its nature as a current signal, hence its widespread use.

Conversely, DC1-5V voltage signals are often used as input signals. To convert a DC4-20mA signal to a DC1-5V voltage signal, a 250Ω resistor is connected in parallel to the input terminal.

2. Power Electronics

In power electronic devices like inverters, current control and monitoring are essential. Shunt resistors are used for controlling and detecting overcurrent. In inverters, they manage the current on the DC side and regulate the output on the AC side.

Also, in industrial rectifiers, shunt resistors are commonly used for current measurement. These rectifiers supply direct current to trains, electrolytic cells, plating tanks, etc., where currents can reach tens of thousands of amperes. Shunt resistors capable of handling these high currents are therefore essential.

3. Electric Vehicles

In electric vehicles, shunt resistors are used for current control, regulating power flow from the battery to the motor and limiting current during rapid charging to protect the battery.

Principle of Shunt Resistors

The fundamental principle of shunt resistors is based on Ohm’s Law, which states that the current (I) flowing through a resistor is proportional to the voltage (V) across it divided by its resistance (R).

Shunt resistors are typically connected in series with the circuit carrying the current to be measured. The same current flows through the shunt resistor. With its known resistance, the current can be calculated by measuring the voltage drop across it with instruments like a voltmeter.

Types of Shunt Resistors

There are various types of shunt resistors, including:

1. Wire Type Shunt Resistor

This common type uses a high-resistance metal wire, thin and wound into a coil, to achieve low resistance. It is versatile and suitable for a wide range of current values, from low to high.

2. Strip Shunt Resistor

Strip shunt resistors use a flat metal strip. Like wire-type resistors, they have low resistance and can handle high currents. They are particularly efficient in heat dissipation, enabling stable operation under high-load conditions.

3. Metal Film Shunt Resistor

Made with a metal film, these resistors involve a metal film deposited on a substrate to form the resistance pattern. Metal film shunt resistors are known for their high accuracy and stability, maintaining consistent performance even with temperature fluctuations.

What Is a Diamond Cutter?

A diamond cutter is a cutting tool designed for the precision cutting of hard materials without the need for traditional grindstones or blades.

It features a disc-shaped design embedded with diamond particles on its cutting edge. Diamond cutters are primarily used for cutting a wide range of materials including stone, ceramics, glass, alloys, and plastics. These cutters are known for their exceptionally sharp edges, enabling high-precision cutting. They offer remarkable durability and rapid cutting speeds. Due to their cutting mechanism, which involves grinding away material, they are often more efficient compared to conventional grindstones or blades. However, it’s essential to employ proper cooling methods when using diamond cutters due to the sensitivity of diamonds to heat.

Uses of Diamond Cutter

1. Stone Cutting
   Diamond cutters are widely employed for cutting stones such as marble, granite, limestone, and more.
2. Ceramics Cutting
   They are used for precision cutting of ceramics, including pottery, tiles, and porcelain.
3. Glass Cutting
   Diamond cutters are essential for cutting glass materials such as sheet glass, mirrors, and glass tubes.
4. Alloys Cutting
   They are used in cutting alloys like stainless steel, aluminum, copper, and more.
5. Plastics Cutting
   Diamond cutters are employed for cutting plastics such as ABS resin, polycarbonate, polyacetal, and others.
6. Semiconductors Cutting
   They play a crucial role in cutting semiconductor materials like silicon wafers with precision.

Features of Diamond Cutter

Advantages

Diamond cutters offer numerous advantages for cutting hard materials:

• Ability to cut extremely hard materials that are challenging or impossible to cut with conventional tools due to the exceptional hardness of diamonds.
• High strength, outstanding durability, and minimal wear and deformation even during extended use.
• Efficient heat dissipation during high-speed cutting, preventing overheating due to the high thermal conductivity of diamonds.
• Exceptionally hard and durable cutting edges coated with diamond powder, allowing for high-precision cutting.

Disadvantages

However, diamond cutters also have some drawbacks:

• Higher manufacturing costs due to the need for expensive materials, as diamonds are exceptionally hard and wear-resistant.
• Susceptibility to chipping or cracking if subjected to impacts or drops due to the brittleness of diamonds, requiring careful handling.

Types of Diamond Cutters

Diamond cutters come in various types based on their shapes, including:

1. Segmented Type

This type is suitable for cutting hard materials like concrete and asphalt. It consists of segments embedded with diamond particles around the cutter’s edge.

2. Rim Type

Used for precision work on materials like ceramics and glass, the rim type features a single row of diamond particles around the cutter, resulting in a smooth cut surface finish.

3. Turbo Type

Combining characteristics of segmented and rim types, the turbo type provides fast cutting speeds with minimal marks on the cut surface. It is commonly used for cutting ceramics, stone, and concrete.

4. Flat Type

Featuring a flat metal plate coated with diamond particles, the flat type is primarily used for cutting softer materials like rebar. It is typically attached to power tools such as circular saws and hand cutters.

How to Use a Diamond Cutter

The process of using a diamond cutter for material cutting involves several steps:

1. Preparation

• Secure the material to be cut.
• Attach the diamond cutter to the cutting device.
• Adjust parameters such as rotation speed, feed rate, and coolant supply as needed.

2. Start Cutting

• Bring the diamond cutter into contact with the material.
• Initiate the cutting process, ensuring that the cutter rotates at an appropriate angle to the cutting surface.
• Gradually press the rotating cutter into the material.

3. Progressive Cutting

• Advance the diamond cutter along the material, adjusting cutting conditions as necessary.
• Ensure proper coolant supply to extend the life of the diamond cutter and achieve a smooth cut surface.

4. Completion of Cutting

Finish the cut, removing any cutting debris or dust generated during the process.

5. Finish the Cut Surface

If required, use appropriate tools to smooth the cut surface.

Other Information on Diamond Cutter

1. Classification Based on Usage Environment

There are two types of diamond cutters based on their usage environment:

Wet Diamond Cutter: Utilizes water for cooling during cutting, minimizing dust dispersion, and ensuring high-quality cutting of hard materials like stone, tiles, ceramics, and concrete.

Dry Diamond Cutter: Cuts materials without the use of water. While it may result in more dust and a rougher cut surface compared to wet cutters, it is suitable for portable power tools and indoor use, commonly used for cutting softer materials like wood, plastic, and metal.

What Is a Refrigerant Recovery Machine?

A refrigerant recovery machine is a device that recovers freon gas into containers such as cylinders.

Freon, chemically known as fluorocarbons, is used as a refrigerant in air conditioning, refrigeration, and cooling systems. Although freon gas is chemically stable, its leakage contributes to the destruction of the ozone layer and the acceleration of global warming, necessitating its recovery rather than release into the atmosphere.

There are broadly two methods of recovery: the gas compression method and the gasification recovery method. The gas compression method involves sucking in the freon, compressing it, and then cooling and liquefying the compressed gas before putting it into a cylinder. On the other hand, the gasification recovery method continuously vaporizes only freon using the adiabatic compression heat of the compressor, allowing for efficient recovery in a short time without being affected by external temperatures. This method also recovers flammable refrigerants dissolved in liquid, gas, and refrigeration oil, allowing for safe discharge.

Refrigerant recovery machines are classified based on the presence or absence of refrigerant regeneration functions, oil-less or oil-in systems, portable or mobile types, and the presence or absence of a function to discharge residual gas in the device.