Often in the work in the construction or repair tools are used such as a punch. Therefore, knowledge of how the perforator is arranged and what its principle of operation is based on is required by every person using this device. A variety of models and modifications of this tool causes a large number of differences in its design, however, the general scheme of the structure of the perforator is retained in any model.
Diagram of the device punch.
The design features of perforators determine the difference in power and functionality of the device. All tools of this type have the following components in their design:
- electric motor;
- impact mechanism;
Additionally, perforators can be equipped with certain systems that can expand the capabilities or make the use of the perforator comfortable. Such systems are:
- anti-vibration system;
- fixing system of the working element;
- mechanism for fixing the depth of drilling;
- dust removal system from the working area;
- mechanism for changing the modes of operation of the instrument.
The design of the punch may vary the location of electric motors. The tool is of two types: with vertical and horizontal placement of the drive.
Electric drive punch
In the role of the engine in the design of the instrument is an electric drive. In the perforators use electric collector type.
Stages lubrication punch.
Lightweight drills used in the subsidiary, have a horizontal placement of the electric motor. In contrast, models of the middle and heavy class, used in professional activities, are usually assembled with vertical placement of the power drive. However, there are exceptions to the rule. For example, a perforator manufactured by Metabo, model Metabo KHE 96 weighing 12 kg, belonging to the class of heavy, has a horizontal system for placing the electric drive.
The tool, which has a horizontal mounting scheme for a power drive, is compact and convenient for use in hard-to-reach and narrow places. This layout of the perforator has several drawbacks, among which the main ones are the high load on the power component and the poor cooling conditions of the electric drive.
A perforator with a vertical installation scheme of an electropower component provides more comfortable conditions for its use. The fact is that the vertical placement of the electric motor reduces the level of shock vibration and provides better cooling of the electric motor. In addition, the vertical layout allows the piston to give a wide amplitude of movement, which increases the amplitude of movement of the striker. This advantage is achieved by using a crank mechanism in a design with a vertical layout for an electric motor instead of a rolling bearing installed in a tool with a horizontal mounting scheme for an electric motor.
Vertical punchers are able to withstand continuous operation, which is inaccessible to a tool with an electric motor installed in a horizontal position.Back to table of contents
Impact mechanism design
The percussion mechanism of the perforator is an important component of the instrument, which is responsible for ensuring the fulfillment of the main function.
The principle of operation of the percussion hammer mechanism.
There are two types of execution of this mechanism:
The electro-pneumatic type of construction of the percussion mechanism is applied in most modern perforators. The advantage of this design is to obtain high impact energy at a small power unit power tool.
There are two options for the design of an electropneumatic shock unit. In one of them the rolling bearing is used, and the work of the second is based on the action of a crank mechanism. The first version of the design is used on light perforators, and the second - on tools of the middle and heavy class.
The design of the percussion mechanism of the light class perforator consists of a rolling bearing, a piston, a battering ram and a striker. At start-up, the rotation from the power electromotor is transmitted to the inner race of the bearing. The outer bearing race with a piston is integral and produces an oscillatory motion.
Three universal modes of operation of the punch.
The air space of the cylinder between the piston and the ram experiences alternately a decrease and increase in pressure. A ram, due to a change in pressure, repeats the movements of the piston and hits the surface of the striker, the movements of the latter affect the bit in the cartridge.
The pneumatic version of the mechanism provides an automatic idle shutdown. This function is performed due to the displacement of the ram forward in the absence of contact of the bit with the surface. When a ram is displaced, a hole is opened to move air between the external environment and the piston chamber.
In instruments of medium and heavy type, which have a vertical arrangement of the electric motor, the piston is driven by a crank mechanism. The high amplitude of operation of this device contributes to an increase in the impact power capable of reaching a value of 20 kJ. The principle of operation of the mechanism is similar to the previously presented type. The rotation through the worm shaft is transmitted to the gear. On the shaft of the last fixed crank, transmitting a pulse to a percussion mechanism.Back to table of contents
Anti-vibration system used in the tool
The scheme of the main parts of the punch, which often break.
Firms are constantly developing new and improve existing systems aimed at reducing vibrations arising in the tool. The whole variety of vibration protection systems can be divided into two types:
The active anti-vibration system is mounted only on a tool with high power. To reduce the level of vibration, an uncomplicated device is used, which consists of a counterweight with a spring device that accepts all vibration loads. This system can not fully compensate for all vibrations that occur in the tool, it only contributes to a significant reduction in its level. In addition, vibration damping is facilitated by a tool handle attached to the body by means of a swivel and a spring mechanism.
The role of the passive system of reducing the level of vibrations arising in the work is performed by rubber lining mounted on the body, in addition, such lining prevents the sliding of hands. The passive system is ineffective.Back to table of contents
Electrical circuit and tool body
Scheme of removal of the lever.
There are many ways to adjust the speed of rotation of the electric power installation tool. You can adjust the rotational speed by changing the pressing force on the start button. In addition, the rotation speed on some device models is set before use by turning the knob of the regulator.
Electric circuits of various models of perforators can have significant differences among themselves. The most simple wiring puncher resembles an electric drill.
The housing for mounting the mechanism is made of metal. As a rule, for its manufacture alloys of aluminum or magnesium are used. For lightweight instrument types, housings are made of impact-resistant plastic. Sometimes you can find models in which metal and impact resistant plastic are used in the manufacture of the case. The metal is much stronger than plastic and contributes to more efficient heat removal, which ensures faster cooling of the mechanisms.
To ensure the mechanisms of the device with effective cooling, air is used which is captured by a fan wheel mounted on the electric motor, which is directed to the impact mechanism and thereby cooling it. This prevents the instrument from overheating during long-term operation. The air flow maintains the optimum temperature of all the mechanisms and the metal casing, which prevents injuries, in addition to this, in order to protect against burns in especially dangerous places, various lining made of plastic is attached to the casing. There are models in which one side of the case is made of metal, and the second of impact-resistant plastic.Back to table of contents
Safety coupling in the tool design
Punching gear reducer disassembly: 1 - special ring, 2 - release sleeve, 3 - ring, 4 - ball, 5 - spring 8 - casing, 22 - closing spring, 28a - switch, 29 - ring, 30 - spring, 31 - clamp.
Perforators are supplied with special couplings that perform a safety role in the event of a chuck stopping during jamming. Jamming threatens to leave the puncher out of working condition or to be injured by a person. To avoid such a situation, the tool is equipped with a special safety clutch. In addition, the clutch is a protective mechanism that prevents the engine from overloading.
In the case of stopping the drill due to the presence of the coupling does not stop the armature of the electric motor. The clutch ensures that the perforator cartridge is disconnected from the motor shaft, preventing it from burning out.
In perforators two types of couplings are used:
The first type of clutch consists of discs that are normally pressed together. When the cartridge stops, the disks slip against each other, which leads to the disconnection of the electric motor from the cartridge. This type of coupling is used in the construction of a tool manufactured by Metabo.
The spring-cam mechanism includes two half-couplings, which at the ends have special projections and depressions. The clamping coupling is carried out by the spring. The principle of operation is based on the principle of slippage of the coupling halves relative to each other in case of jamming of the tool. When the mechanism of this type of clutch actuates, a characteristic crackling of the teeth is heard.
It is considered that the spring-cam system is more reliable than the friction one. The latter has a drawback - when operating, the ends of the protrusions on the half-couplings are rolled, which leads to the operation of the coupling in the absence of jamming of the cartridge.Back to table of contents
Perforator Reducer Design
The gearbox is required to transfer rotation to the punch chuck. In addition, the gearbox ensures the functioning of the percussion mechanism. It consists of various types of gears. Gearboxes have a constant gear ratio.
Adjusting the speed of the punch chuck is carried out using a special electronic regulator. It is worth noting that today developed and manufactured models with two-speed gearboxes. To lubricate the gears of the mechanism used grease, which is charged during assembly or in the process of repair.Back to table of contents
Diagram of the device components of the punch.
Today in the design of perforators use three types of cartridges. The cartridge punch can have the following designs:
- quick clamping;
- SDS systems.
The latest type of cartridges is equipped with up to 90% of all manufactured perforators on the market of construction tools. The cam cartridge is the key cartridge of the perforator, in which the nozzle is clamped with a special key, which spreads and reduces the cams.
Keyless chuck is characterized by the fact that the clamping of the nozzle is made exclusively with the help of hand strength. This type of ammunition has two subtypes - single and dual muff. Such cartridges are used on perforators with automatic shaft locking.
The cartridge of the SDS system is fast-tightening and works on the principle of "inserted, turned - fixed".