Knowledge introduction of percussion drill Encyclopedia
The percussion drill works by rotation and impact. The percussion drill works by rotation and impact. A single impact is very slight, but a frequency of more than 40000 per minute produces a continuous force. It can be used in natural stone or concrete. When the impact drill works, there are adjustment knobs at the bit chuck, which can be used to adjust the ordinary electric hand drill and impact drill. But the impact drill uses the gears on the inner shaft to achieve the impact effect, but the impact force is far less than that of the electric hammer. It is not suitable for drilling reinforced concrete.
Introduction of hand impact drill
Impact drill: the impact mechanism of impact drill has canine type and ball type. The ball type impact drill is composed of moving disc, impact drill, fixed plate and steel ball. The moving disk is connected with the main shaft by thread and has 12 steel balls; the fixed plate is fixed on the casing with 4 steel balls. Under the action of thrust, the 12 steel balls roll along the 4 steel balls, making the carbide drill bit produce rotation impact movement, and can drill holes on brittle materials such as brick, block and concrete. It can be used as an ordinary electric drill.
Usage description
It is mainly used for percussion drilling on concrete floor, wall, brick, stone, wood board and multi-layer materials; in addition, it can drill and tap on wood, metal, ceramic and plastic, and is equipped with electronic speed control equipment for forward / reverse functions.
The motor voltage of impact drill has two different voltages: 0v-230v and 0v-115v. It controls the clutch of the microswitch to obtain two different speeds of the motor. It is equipped with forward and reverse steering control mechanism, elastic screw and tapping function.

Main structure
(1) Power switch.
(2) Reverse limit switch.
(3) Drill collet.
(4) Voltage regulation and clutch control twist of power supply.
(5) Change the voltage to realize the secondary transmission mechanism.
(6) Auxiliary handle, locating ring, housing fastening screw, etc.
(7) Steering control mechanism in the forward and reverse direction.
(8) Gear set in the machine.
(9) The case insulation holds a handshake.
Relevant accessories
(1) Spare parts for special hand and electric drill.
(2) Super drill chuck.
(3) Special drill collet key.
(4) The fuselage can be adjusted to assist the depth gauge.
(5) Diamond bit.
(6) Plug in the power cord.
(7) Carbon brush, terminal.
(8) Adjust the limit twist of the auxiliary handle and ruler.
(9) Special disassembly and assembly and electrical testing tools, etc.

Use and maintenance
The impact drill is of double insulation design, safe and reliable operation. It does not need to use protective grounding (neutral connection), and can use single-phase two pole plug. It can be used without wearing insulating gloves or insulating shoes. In order to make the operation convenient, flexible and powerful, the impact drill is generally equipped with an auxiliary handle. Since the impact drill adopts double insulation and has no grounding (neutral) protection, special attention should be paid to the protection of rubber sheathed cables. When moving the drill by hand, you must hold the handle of the drill, and do not drag the rubber sleeve cable. The rubber sheathed cable shall not be rolled by the wheel or stepped on by the foot; it shall be prevented from being bitten by rats.
Correct use
(1) Before operation, it is necessary to check whether the power supply is consistent with the normal rated voltage of 220 V on the electric tools, so as to avoid wrong connection to the 380V power supply.
(2) Before using the impact drill, please carefully check the insulation protection of the machine body, the adjustment of auxiliary handle and depth gauge, and whether the screw of the machine is loose.
(3) The impact drill must be installed into the alloyed steel impact bit or drilling universal drill bit within the allowable range of φ 6-25mm according to the material requirements. It is strictly forbidden to use drill beyond the scope.
(4) The wire of percussion drill shall be well protected. It is strictly forbidden to drag the wire all over the ground to prevent rolling damage and cutting. Moreover, it is not allowed to drag the wire into the oil water to prevent the oil and water from corroding the wire.
(5) The power socket of impact drill must be equipped with leakage switch device, and check whether the power line is damaged. When the impact drill is found to have leakage, abnormal vibration, high heat or abnormal sound during use, the work shall be stopped immediately and the electrician shall be asked to check and repair in time.
(6) When the impact drill bit is replaced, the special spanner and the lock key of the drill bit shall be used to prevent the use of non special tools to knock the impact drill.
(7) When using the percussion drill, remember not to use too much force or skew operation. Be sure to install the appropriate drill bit and adjust the depth gauge of the impact drill in advance. The vertical and balanced operation should be carried out slowly and evenly, and the super large drill bit should not be used forcibly.
(8) Master and operate clockwise and reverse steering control mechanism, elastic screw and drilling and tapping functions.
Maintenance
(1) The carbon brush of impact drill shall be replaced regularly by professional electrician and the spring pressure shall be checked.
(2) Ensure that the whole body of the percussion drill is in good condition and clean, and the dirt is removed, so as to ensure the smooth running of the impact drill.
(3) Professional personnel shall regularly check whether the components of electric hand drill are damaged, and timely replace those that are seriously damaged and can not be reused.
(4) Timely supplement the body screws and fasteners lost due to operation.
(5) Regularly check whether the bearings, gears and cooling blades of the transmission part are flexible and intact, and timely add lubricating oil to the rotating parts to prolong the service life of the electric hand drill.
(6) After use, the electric hand drill should be returned to the tool library for safekeeping. Do not store overnight in personal tool cabinet.

Safe operation procedures
(1) At work, we must be attentive, not only to maintain a clear mind, but also rational operation of electric tools, tired, strictly prohibited after drinking or taking stimulants, drugs to operate the machine.
(2) The impact shell must be protected by grounding wire or neutral line.
(3) The electric drill wire should be in good condition. It is strictly forbidden to drag it to prevent rolling damage and cutting. It is forbidden to drag the wire into the oil water to prevent the oil and water from corroding the wire.
(4) Check whether the insulation is intact and whether the switch is sensitive and reliable.
(5) The clamping bit should be used with proper force. It should be idled for a few minutes before use, and can be used after the normal rotation.
(6) When drilling, make the drill bit contact with the workpiece slowly, do not use too much force, break the drill bit and burn out the motor.
(7) Pay attention to the standing posture at work and do not take it lightly.
(8) When operating the machine, be sure to stand firmly and keep balance at all times.
(9) When using electric drill in dry place, it is forbidden to wear gloves to prevent accidents caused by bit stranding. When using an electric drill in a humid place, you must stand on a rubber pad or a dry board to prevent electric shock.
(10) In case of electric drill leakage, vibration, high temperature and overheating, the drill should be shut down immediately and used after cooling.
(11) When the electric drill does not stop rotating completely, it is not allowed to unload or replace the drill bit. In case of any abnormality, no one else is allowed to disassemble and assemble the drill by himself, and the drill shall be repaired by a specially assigned person in time.
(12) In case of power failure, rest or leaving the work place, the power supply shall be cut off immediately.
(13) If the pressure drill is used, the drill must be vertical and the fixed end must be firm and reliable.
(14) When drilling along the original hole, do not use sudden force to prevent the bit from breaking.
(15) When using the impact drill, such as working in wet places, it must stand on the insulating pad or dry wood board. Safety protection measures must be taken when climbing high or using in explosion-proof and other dangerous areas.
(16) Wear appropriate work clothes, do not wear too loose work clothes, do not wear jewelry or long hair, do not wear gloves and cuffs do not buckle the operation of electric tools.
(17) Don't leave it anywhere. At the end of the work, the drill and insulation should be placed in the designated place.
matters needing attention
Generally speaking, percussion drill can not be used as electric drill: first, it is difficult to grasp the direction of impact drill when using, and it is easy to misoperate, and the opening is too large; second, the drill is not sharp, so that the hole is not neat, burr or crack; third, even if there is a conversion switch above, try not to drill, unless you use a special drill bit, but because of the electric drill It is easy to blacken the hole and heat the drill bit, thus affecting the service life of the bit.
Introduction to percussion drill for piling: percussion drill, bridge and culvert or high-rise building may need to drive ground pile. Percussion drill can be selected for construction according to local geological conditions. Impact drill is a kind of drilling rig. It is mainly used for drilling construction in hard geological and rock formations.
Drilling rig is divided into: rotary drill, impact drill, truck drill, positive circulation drill, reverse circulation drill.

Construction process
1. For geological re survey, it is necessary to select the drilling site within the drilling scope and check the geological conditions of the pile foundation location to see whether it is consistent with the design. It is necessary for large-scale, large-scale and large-scale projects, and pile test should be conducted for super large projects.
2. According to the site conditions, select the construction method, island or cofferdam, whether trestle is needed, reasonably arrange the site, select the drilling sequence reasonably, reduce the turnover of drilling rig, and do not affect the adjacent holes; if it is necessary to build an island, the materials are generally selected nearby, and the material is generally not limited, but the height of the island should be more than 2m higher than the historical maximum water level in the construction area It's very important.
3. According to the site geological conditions, the reasonable selection of impact drill, 8t or 10t depends on the geological conditions, for the rock with high hardness, it is recommended to select 10t drilling rig; the diameter of the drill bit is 5cm smaller than the designed diameter.
4. Steel casing processing, according to the actual geological conditions of the site, through the calculation of lateral pressure, the thickness of steel plate is selected. Generally, the rolled section is processed in the steel formwork factory, and the welding is followed up when drilling on site. The depth of follow-up of casing generally considers that the bottom opening is located in hard rock stratum, and special attention should be paid to penetrating the quicksand layer. The steel casing is processed for about 3 m as a section, and cross bracing is added during transportation. The blade foot of the first section of casing shall be strengthened to prevent follow-up curling.
5. In fact, percussive drilling is the same as many underwater pile foundation construction techniques. One of the most important key points is the slurry wall protection, which must have a small sand content. The density of the retaining wall can be judged by experience or by experiment. If the mud is too thick, the drilling speed is slow and the mud is too light, the wall protection is easy to collapse. Mud production should also be determined according to the difficulty of the project. For some geological conditions, ordinary clay can be used to make slurry, while for some geology, the mud mix proportion should be selected reasonably according to the requirements (determined by test). Especially in coastal areas, salinization is very serious, which needs special consideration.

6. Key points of drilling: it is better to start drilling slowly rather than fast, because there is a process of compaction around the edge foot of casing, which requires repeated impact and extrusion, because this position is the most easy to perforate; The perpendicularity correction should be carried out immediately after 2-3m. If the borehole is too deep and the deviation is too large, only the backfill will come again (in fact, the specifications are false, but the most important thing is that after the earth around the pile head is excavated, it must look horizontal and vertical to the naked eye). Generally, the rock stratum is inclined, which is perpendicular to the contact surface of the drilling rig. At this position, the gravel is backfilled to drill repeatedly until the rock layer is flat. How to judge? If the steel wire rope sways violently, it may be the case. It is easy to get stuck, the drill bit tilts and reverses, and the hole position inclines. The casing shall be followed up in time, and the water head in the casing must be maintained. Mud index should be checked and controlled at any time. Drilling rig and steel wire rope should be inspected at any time. It is very difficult to deal with the dropping of drilling. The geological conditions should be judged according to the drilling slag every day. After drilling to the design position, the supervisor should be informed to check and accept together to determine whether the bottom geology is consistent with the design. The owner, design and investigation should be informed of the first pile foundation inspection hole.
7. The whole process of drilling should be strictly controlled, but there is no need to worry when there is a fault. Generally, it can be solved by reasonable selection of treatment methods. Generally, there are some common problems, such as cutting edge perforation, hole collapse, deviation hole, cross hole, sticking, buried drill, hanging drill, etc. if preventive measures are taken in advance, it is very important for the duty personnel to have a sense of responsibility.
8. The remaining hole cleaning, reinforcement cage lowering, concrete pouring and sealing are relatively conventional, not to write more. However, the residue and precipitated sand at the bottom of the hole must be cleaned up circularly, otherwise, the hidden danger will be buried in the later stage of the project. When pouring concrete, under the impact of back cover concrete, the residue will be mixed on the reinforcement or wrapped in the concrete, resulting in pile foundation defects. In addition, when the upper structure load is transferred to the pile bottom, the structure will definitely produce uneven settlement for the residue.

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