A impact wrench (also known as crasher , impact gun , air wrench , air rifle , rattle gun , torque gun , windy gun ) is a power socket wrench tool designed to produce high torque output with minimal power deployment by the user, by storing energy in a rotating mass, then sending it suddenly to the output shaft.
Compressed air is the most common source of electricity, although hydraulic power or power is also used, with wireless electrical devices becoming increasingly popular since the mid-2000s.
Impact wrenches are widely used in many industries, such as automotive repair, heavy equipment maintenance, product assembly, major construction projects, and other examples where high torsional output is required. For product assembly, pulse tools are typically used, due to the unresponsive firming feature while reducing the usual noise level. The pulse tools use oil as a medium to transfer the kinetic energy from the hammer to the anvil. This provides a finer impulse, a slightly lower torque to weight ratio and the possibility to design a lethal mechanism that closes the tool when it reaches the correct torque. Pulse tools are not called "impact wrenches" because performance and technology are not the same.
The impact wrench is available in every standard drive socket lock size, from small "drive" tools to small assembly and disassembly, up to 3Ã,½ "and larger rectangular drives for large construction.Electric fitting is one of the most common air tools used.
In operation, the rotating mass is accelerated by the motor, storing energy, then suddenly connected to the output shaft (grounding), creating a high torque impact. The hammer mechanism is designed so that once it has its effect, the hammer is once again allowed to spin free, and not locked. With this design, the only reaction force applied to the body of the tool is the motor accelerating the hammer, and thus the operator feels very little torque, although very high peak torque is sent to the socket. (This is similar to a conventional hammer, where the user implements a small, constant force to swing the hammer, which produces very large impulses when the hammer attacks the object.) The design of the hammer requires a certain minimum torque before the hammer is allowed to spin separately from the runway, causing the tool to stop hammering and instead moving the fasteners fast if only low torque is required, quickly attaching/removing the binder.
Video Impact wrench
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Compressed air is the most common resource for impact wrenches, providing a low-cost design with the best power-to-weight ratio. Simple propeller motors are almost always used, usually with four to seven propellers, and various lubrication systems, most commonly using oily air, while others may include special oil channels directed to the necessary parts and separate sealed oil systems for hammer assembly. Most wrenches drive the hammer directly from the motor, giving it fast action when fasteners only require low torque. Other designs use a gear-reduction system prior to the hammer mechanism, most often being a single-level planetary gear usually with heavier hammers, providing more constant speed and higher "spin torque". Power impact wrench available, whether powered, or for automotive use, 12-volt, 18-volt or 24-volt DC-powered. Recently, electric wrench impact wrenches have become common, although usually their power output is significantly lower than equivalent electric or equivalent power equivalent. Some industrial equipment is hydraulically driven, using high-speed hydraulic motors, and is used in some heavy equipment workshops, large construction sites, and other areas where appropriate hydraulic supplies are available. Hydraulic impact wrenches have a high power-to-weight ratio advantage.
Maps Impact wrench
Size and style
The impact wrench is available in all sizes and in some styles, depending on the application. Ã,¼ "drive wrenches are commonly available in both inline (user holding tool such as a screwdriver, with output at the end) and grip gun (user holding the handle that is at right angle to output) shape, and less common in angle drives, which are similar with an inline tool but with a set of bevel gears to rotate the output of 90  ° 3. 3/8 "impacts most often available in the form of a pistol grip and a special inline shape known as a" butterfly "wrench, which has a throttle paddle large, flat side of the tool that can be tilted to one side or the other to control the direction of rotation, rather than using a separate reversal control, and is formed to allow access to a narrow area. Regular inline and 3/8 "angle drive impact wrench are not common, but available ½" drive units are virtually available only in the form of grip pistols, with inline types that are virtually impossible to obtain, as torque increases are transmitted back to the user. and the heavier the tools that require greater grip. Ã,¾ "The impact wrench of the drive again is basically only available in the form of a pistol grip.1" the drive tool is available in both handles of the gun and the inline "handle", where the back of the tool has a closed handle for the user to hold. Both forms often also incorporate side grips, allowing both hands to hold the tool at once. 1Ã,¼ "and larger wrenches are usually available in the form of" T handle ", with two large grips on either side of the tool body, allowing maximum torque to be applied to the user, and giving the best control of the appliance. (up to several hundred thousand feet-pound torque) typically incorporate fish eyes in their design, allowing them to hang from cranes, lifts, or other devices, because their weight is often more than a person can move in. The design recently incorporates a key fitting impacts and air ratchet, often called "air ratchet without reaction" by the manufacturer, incorporating impact assembly before ratchet assemblies.These designs allow very high output torque with minimal effort on the operator, and prevent common injury from slamming one's fingers to multiple parts of the equipment when fasteners tighten and torque suddenly increases Special design is available for apps ation, such as taking off your crankshaft pulley with you. t remove the radiator in the vehicle.
A variety of methods are used to install a socket or accessory to the runway, such as a spring pin that enters a suitable hole in the socket, preventing the socket from being released until the object is used to press pins, pig rings that hold sockets by friction or by flicking to indent the machine to the socket; through the hole, where the pin is inserted completely through the socket and grounding, locking the socket on. The pig ring is used on the smallest tool, with holes used only on larger impact wrenches, usually Ã,¾ "drives or larger.Pack pegs are used to be more common, but appear to be replaced by pig rings in part large appliance, although no positive keys. Ã,¼ "female hexa drives are becoming increasingly popular for small impact wrenches, especially the cordless electric version, allowing them to customize a standard screwdriver tip rather than a socket.
Many users choose to equip air-powered wrenches with shorter air hoses than to install a direct connection to the appliance. Such hoses are helpful in installing a wrench to a narrow area, with no complete coupler assemblies sticking out the rear of the tool, as well as allowing users to place tools. The additional benefit is greatly reduced in use on the coupler, by isolating from the vibration of the appliance. Short hose also prevents air fitting broken at the base of the appliance if the user loses his grip and the tool is allowed to spin.
Effect of impact drive
As the output of the impact wrench, when hammering, is a very short impact force, the actual effective torque is difficult to measure, with several different ranks being used. Since this tool provides a fixed amount of energy with each puff, rather than a fixed torque, the actual output torque changes with the duration of the output pulse. If the output is supple or capable of absorbing energy, the impulse will only be absorbed, and almost no torque will be applied, and somewhat intuitively opposite, if the object is very elastic, the wrench may actually turn back because its energy is sent back to the ground, it is not connected to a hammer and can spin freely. A wrench capable of freeing rusted nuts on a very large bolt may not be able to turn a small screw mounted on a spring. "Maximum torque" is the number most often given by the manufacturer, which is the instantaneous peak torque that is shipped if the ground is locked into a very solid object. "Working Torque" is a more realistic number to continue riding very stiff fasteners. The "peacock-busting torsion" is often quoted, with the usual definition being that the wrench can loosen the hardened nut with the amount of torque specified in certain periods of time. Accurately controlling the output torque of the impact wrench is very difficult, and even experienced operators will have trouble ensuring fasteners are not too tight or too tight with impact wrenches. Special socket extensions are available, which utilize the impact wrench's disability to work against springs, to precisely limit the torque output. Designed with spring steel, they act as large torque springs, stretch their torque values, and prevent further torque from being applied to the binder. Some impact wrenches designed for product assembly have an internal torque control system, such as a built-in torque spring and a mechanism that switches off the appliance when a given torque is exceeded. When a precise torque is required, the impact wrench is used only for the fastening of the fastener, with the key moments used for the final tightening. Due to the lack of standards when measuring maximum torque, some manufacturers are believed to increase their ratings, or use measurements with few pads about how the tool will perform in actual usage. Many air impact wrenches incorporate flow regulators into their designs, either as separate controls or parts of the inverting valves, allowing torque to be roughly confined in one or both directions, while electric appliances can use variable speed triggers for the same effect.
Mechanism hammer
The hammer mechanism in the impact wrench should allow the hammer to rotate freely, crash into the runway, then release and rotate freely again. Many designs are used to accomplish this task, all with some shortcomings. Depending on the design, a hammer can push anvil either once or twice per revolution (where the revolution is the difference between a hammer and a foundation), with some designs giving faster, weaker blows twice per revolution, or slower, stronger only once per revolution.
The general hammer design has a hammer that can slide and rotate on the shaft, with the spring holding it in the bottom position. Between the hammer and the drive shaft is a steel ball on the road, so that if the input shaft rotates in front of the hammer with sufficient torque, the spring is compressed and the hammer slid backwards. At the bottom of the hammer, and the top of the runway, is a dog tooth, designed for high impact. When this tool is used, the hammer rotates until its dog's tooth touches the tooth on the runway, stopping the hammer from spinning. The input shaft continues to rotate, causing the ramp to lift the steel ball, lifting the hammer unit until the dog's teeth no longer use the runway, and the hammer is free to rotate again. The hammer then springs forward to the bottom of the ramp balls, and is accelerated by the input shaft, until the dog's teeth contact the runway again, giving impact. The process then repeats, blows every time a tooth meets, almost always twice per revolution. If the output has a bit of load on it, such as when rotating loose nut on the bolts, the torque will never be high enough to cause the ball to solidify the spring, and the input will smoothly drive the output. This design has the advantage of small size and simplicity, but wasted energy moves the whole hammer back and forth, and gives some punches per revolution giving less time for hammers to accelerate. This design is often seen after the reduction of gear, compensating for the lack of acceleration time by providing more torque at lower speeds.
Other common designs use a hammer that is mounted directly into the input shaft, with a pair of pins that serve as a grip. When the hammer spins over the runway, a ball ramp pushes the pin outward against the spring, extends to where they will hit the runway and give effect, then release and return to the hammer, usually by making the ball fall "" The other side of the slope when the hammer is hit. Since the ramp only needs to have a peak around the axis, and the hammer involvement with the foundation is not based on a number of teeth between them, this design allows the hammer to accelerate the full revolution before contacting the runway, giving it more time to accelerate and give a stronger impact. The disadvantage is that the sliding pin must handle a very high impact, and often lead to early failure of the tool.
Yet other designs use heavy rocking inside the hammer, and a long bulge on the side of the anvil shaft. When the hammer turns, the shake load first contacts the base on the opposite side of the one used to move the runway, nudging the load into position. As the hammer spins farther, its weight touches the side of the runway, moving its own hammer and energy to the output, then back to the other side. The design also has the advantage of hammering only once per revolution, as well as its simplicity, but has the disadvantage of making the device vibrate because rocking weight acts as an eccentric, and can be less tolerant of running tools with low input power. To help combat vibrations and uneven drives, sometimes these two hammers are placed parallel to each other, at 180 ° offsets, both conspicuous at the same time.
The new design (as of 2016) encloses the pounding mechanism in hydraulic fluid to reduce the amount of metal to metal contact, greatly reducing noise and vibration.
Sockets and accessories
Sockets and extensions for impact wrenches are made of high tensile metal, as any spring effect will greatly reduce the torque available on fasteners. However, the use of multiple extensions, universal connections, and so on will weaken the impact, and operators need to minimize their use. Using a non-impact socket or accessory with impact wrenches often causes bending, fracturing, or damage to the accessory because most are unable to withstand a sudden high torque collision, and may cause head stripping of the binder. Non-impact sockets and accessories are made of tougher, brittle metal. Safety glasses should always be worn when working with impact tools, because strong impacts can result in high-speed shrapnel if the socket, accessory, or fasteners fail.
See also
- Lock socket
- Torque multiplier
- Pneumatic torque key
- Impact driver
- Hydraulic torque lock
- Air tools
References
External links
- Basic Automotive & amp; Maintenance
- Outdoor Electrical Equipment
Source of the article : Wikipedia
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