MECHANICAL MECHANISM. Automatic center punch
Removing the mode switch
To remove the mode switch, you must:
- Move the toggle switch to the “strike” position (the hammer icon) and turn it about 1 cm below.
- Free the lever from the socket.
- Pull the lever towards you.
The switch is removed in a position below the “shock”
Grease
Failure to change the grease can also be the reason for the lack of shock. Working with a hammer drill implies the presence of dust, which does not in the best way affect the properties of lubricants. Dust can clog the holes in the cylinder that allow air to circulate when the hammer is operating. The same effect is not excluded when using a grease that is too thick, not intended for rock drills.
Disassembly and assembly procedure
You should start disassembling yourself only if you have the appropriate tools and equipment. To repair a punch with your own hands you will need:
- screwdrivers with different slots;
- vice;
- wrenches and socket (hex) wrenches;
- bearing pullers.
In addition, you will need spare parts for replacement, rubber seals and gaskets. To lubricate the gears of mechanisms you will need:
- grease;
- rags;
- cleaning solvent.
In case of self-repair of the electric motor, in addition to the multimeter, you will need:
- spare carbon (or graphite) brushes;
- copper wire of the required section;
- rewind template.
How to change bearings
If, during a routine inspection, grease drips are noticeable on the bearing, it cracks or crunches when turned by hand, this means that it is time to replace it. The bearing is dismantled using a special puller consisting of a screw part and a device for gripping the bearing sleeve housing. Thread tightening creates a force that pulls the bearing off the shaft.
The puller is driven by the rotation of the threaded rod
The installation of a new bearing in the workplace is done with a rubber or wooden hammer padding. When installing, it is important to avoid misalignment of the bearing axis relative to the shaft axis. Part is lubricated after installation.
Possible malfunctions, reasons for their occurrence and remedies
To repair a hammer drill with your own hands, you must first determine the external manifestations of malfunctions.
The hammer drill does not hold a chuck
Sometimes there is a situation when a cartridge flies off on a working perforator along with the equipment. This is due to the wear of the holder of the chuck body at the end of the trunnion sleeve, which is a retaining ring. If it breaks, the fixation is broken and during the push, the rubber boot flies off, followed by the spring and balls.
Normal operation of the chuck can be restored by installing a new retaining ring. This is done quickly and does not require any additional devices besides the usual screwdriver.
Instrument device and its mechanism
The functional purpose of the punch is determined by its internal structure.
The reinforced impact-rotational mechanism of the tool is the so-called “swing bearing” or “crank connecting rod”, which, rotating from the engine, transmit vibrations to the pneumatic pistons (or piston), after which the air injected in the pistons is pushed with a blow by the firing pin with a nozzle.
The impact force of 17-20 kilojoules and the parallel rotation of the displacer due to the transmission gear ensures the entry of the chisel or drill into the material of high density. It is necessary for punching through holes or chipping holes for electrical wiring or plumbing pipes.
Bearings
To remove a damaged bearing, the technician uses a specialized puller to detach the retaining ring (if holding the part). A rotational movement along the thread “unscrews” the old bearing from the shaft. The new part is hammered onto the shaft with a wooden or rubber “soft” hammer, after which it is lubricated.
Reasons for not hitting
At first glance, it seems that the striking mechanism has a simple design, and there is nothing to break there. Load, dust and vibration gradually take their toll. Typically, the force of impact decreases as the mechanism wears out and eventually comes to naught. The sharp disappearance of the impact is due to the deformation or destruction of some parts.
Troubleshooting
When starting to inspect a punch, they usually start with the power cord and plug. To begin with, it is enough to examine it. For a more accurate diagnosis, use an automotive or household ammeter or multimeter.
If a fault is identified in the cord, it is replaced entirely by picking up or buying a new one, with a wiring cross-section corresponding to the power consumption of the device.
If it was found that the cord is not damaged, proceed to diagnostics of the internal structure of the instrument. The main malfunctions of a punching tool are divided into:
- failures in mechanical assemblies and components;
- failures in the electro-dynamic “stuffing”.
Important. Before opening the device case with your own hands, it is recommended to prepare in advance the workplace and the necessary tools for diagnostics and repair. screwdrivers or a multifunctional electric screwdriver, wire cutters and pliers, a rubber hammer, a vice and wrenches for different diameters of nuts, a magnet, a set for cleaning and lubrication.
Replacement of main components
If, during the diagnosis, the wizard determines that one of the main components has become unusable, he will replace it in order to avoid damage to the rest of the device.
Cartridge
Repair, cleaning and lubrication of chuck assemblies is easily done in a home workshop. However, in the event that one or more parts have worn out to a dangerous limit, the cartridge is removed, as described above, and the unusable parts are replaced.
How to remove the mode switch
To diagnose internal components, it is necessary to remove the punch body and clean the surface of the components from dust. Parsing begins with the separation of the operating mode regulator.
It is moved all the way. as a rule, this is the extreme right position (below the bump mode icon), after which, prying it with a flat screwdriver, remove the regulator from its socket.
Rotary hammer designs
Perforator designs. Portable rock drills differ little from each other in design. Consider the device of one of the common perforators PP63V (Fig.16.8).
It consists of a cylinder 1, a barrel 2 and a rear cover 11, interconnected by tie bolts 10 with nuts. The piston-striker 3 under the action of compressed air supplied alternately to the front or rear relative to the piston of the cylinder cavity, makes a reciprocating motion. The sequence of supply of compressed air is regulated by a valve air distributor 15. At the end of the working stroke, the piston-striker strikes the drill shank with its rod. During the return stroke, the piston-striker with the help of the mechanism 9 turns the drill by a certain angle. To remove destroyed rock from the hole, the perforator has a flushing device 12, which supplies water to the bottom of the hole through the perforator flushing pipe, the axial channel in the rod and the holes in the bit.
The drill holder 4 serves to center the drill while drilling the hole and extract the drill from the hole. The noise muffler 16, made of rubber, is installed above the exhaust holes in the cylinder wall and can be rotated relative to the cylinder, which allows the exhaust air to be directed away from the driller. To support the rock drill during operation, there is a handle 8 connected to the rock drill through a vibration damping device 7. It is a tubular metal structure with a spring vibration damping system 5. The perforator is connected to the supporting devices with a bracket 6. Telescopic perforators (Fig. 16.9) differ from portable ones by the presence of a pneumatic telescopic feeder and a device that protects the perforator mechanisms from getting cuttings from the borehole into them. The telescopic feeder consists of a cylinder 13, a piston 11 with a rod 12. The stop 14 keeps the perforator from turning during drilling and displacement along the surface on which it is installed (excavation soil, working shelf, etc.).
DIY punch repair
Rather, the reason is the striker. And, perhaps more sealing rings Depressurization. no pressure is created. the striker does not move.
How to carry out the correct repair of a punch on your own
The working mechanism remains stationary.
Shaft revolutions are adjusted by pressing a button, if a soft start is provided. On some models, the button has a trigger limit adjustment knob that adjusts the RPM and engine power.
The rotary hammer reducer facilitates the transmission of the speed with the appropriate parameters of power and torque from the initial unit (engine) to the final unit (percussion mechanism). Reducing the gear ratio is necessary for the normal operation of the entire apparatus with its vibration parameters. The reduction type of the gearbox leads to a lower number of engine revolutions and an increase in the power of the final unit. To lubricate it, use a specialized dense grease such as solid oil, refueled during manufacture or maintenance.
The punch body is made mainly of metal (dural alloys, steel), only near the electrical part, in the area of the trigger button, it is made of durable plastic.
Self-repair of a hammer drill
If you need to repair a hammer drill, then this means, at least, that you already have it. Although it is quite possible that you are just choosing this percussion drilling tool, while simultaneously studying the weak points of its design, and which nodes in it could theoretically fail.
Well, let’s try to help you. In this article, we will explore:
- Perforator device.
- The most loaded parts and assemblies of the tool.
- Disassembly and assembly.
- Measures to Extend the Life of Impact Drilling Power Tools.
Studying the principle of operation of a percussion-drilling tool will not only expand your technical horizons, but first of all will allow you to competently carry out its maintenance and, if necessary, repair. To make it easier to understand the processes occurring during drilling in hard materials (and this tool is designed to perform just such work), do not be too lazy to watch these two short videos. The first clearly shows the operation of a rotary hammer with a longitudinal engine.
The second video demonstrates the design of a rotary hammer with a transverse engine.
So, let’s start with the most important thing: the tool destroys concrete, brick, stone by a shock wave that occurs at the moment of a very short contact of the striker with the end of the drill (through the striker). The energy of the shock wave is transmitted through the drill (impact drill) and breaks the bonds (forms microcracks) between the grains of the minerals that make up the stone (concrete, brick). Spiral grooves of the rotating drill are used to remove the breakaway material particles from the hole.
(Hence the conclusion: there is no need to press hard with a perforator on a concrete wall, it will not drill faster. only you will get tired yourself, and the tool will break faster.)
The hammer is made of high-strength steel and moves freely enough inside the piston cylinder.
A rubber sealing ring seals the gap, preventing air from freely passing into the gap between the cylinder and the hammer.
The outer race of a rolling bearing, set at an angle on a shaft rotated by an electric motor, reciprocates, forcing the piston cylinder to move back and forth.
How to repair the Makita HR 2450 rotary hammer if the impact mode is gone
When the cylinder is moved forward (towards the drill), the striker remains in place by inertia, the air between the striker and the rear wall of the cylinder is compressed and pushes the striker towards the end of the drill.
In fact, this air serves as a damping element that prevents deformation and destruction of the cylinder of the rock drill. In a tool with a transverse engine, the cylinder is stationary, and the vacuum and compression of air behind the striker is created by a piston driven by a crank mechanism.
The most loaded parts and assemblies of the hammer drill
Based on the foregoing, the impact mechanism and gearbox experience maximum loads during long-term operation. Part of the kinetic energy of the striker is converted into thermal energy, and heats the entire unit. The O-ring constantly rubs against the inner surface of the cylinder and, if there is a lack of lubrication, wears out, over time letting in more and more air from the working area.
The energy of the compressed air becomes less and less. the hammer drill no longer chisels as needed. When self-repairing a perforator, sometimes it is enough just to replace the lubricant in the gearbox, piston cylinder and rubber sealing ring on the drummer.
During prolonged continuous operation or during normal drilling under a high load, the electric motor can easily overheat and burn out. Although the latest models of the tool have an electronic control unit that includes motor overload protection. If you wish, you can read about troubleshooting the electric motor, power cord, electronics and power button in the previous article.
Disassembly and assembly of the rotary hammer
When trying to repair a punch with your own hands, first of all, you need to disassemble it. To do this, remove the rubber tip, the annular spring, the casing of the drill fixing clutch. The retaining steel ball is removed. By turning the operating mode switch to the extreme position, pressing the locking button on it, the switch handle is removed.
The rear handle pad is removed, the electric motor brushes are removed. 4 screws are unscrewed (from the side of the drill) and the entire front part of the tool (gearbox housing) is removed, containing the barrel, gearbox, percussion mechanism and operating mode switch.
The rotor of the engine is removed. The two screws securing the stator are unscrewed. 4 terminals are removed from the stator contacts, then it is removed from the case. Removable switch (reverse switch button), brush holder, noise filter and power cord.
If it is necessary to repair the perforator in the part of the percussion mechanism and the gearbox, 4 screws are unscrewed from the end of the gearbox housing, then the outer plastic casing is removed. It is better to do this in an upright position. Then, in the inner case, all parts will remain in their places.
After replacing the defective part, the assembly is carried out in the reverse order. The parts that turned out to be “superfluous” should be wiped dry and taken to the repair shop along with the hammer drill.
Measures that prolong the “life” of the hammer drill
- Carefully read the user manual and the instruction manual of the tool.
- Strictly follow the instructions specified in the instructions.
- Replace the lubricant of the gearbox and hammer regularly. Replace it, since there is no point in adding new grease to the old one. metal dust serves as an excellent abrasive, “eating up” everything in its path.
- Lubricate the drill shank before use.
- Inspect motor brushes regularly and replace as needed.
- Clean the outside of the tool every day after finishing work.
- Try not to work in clouds of dust. it is harmful not only for the hammer drill, but also for your lungs. Ventilate your work area by opening all windows.
- Do not go there, in which you do not understand anything at all. entrust the service to a professional, or, if you have already undertaken to repair the puncher with your own hands, then do it slowly, remembering well where you put what.
The design features of rock drills suggest some differences in the location of standard mechanisms. The main nodes are unchanged in any model. This is an electric motor, a reduction gear, a complex impact mechanism, an end working part (cartridge). The basic principle of operation is the conversion of the kinetic energy of the rotational motion of the engine into impact energy due to the oscillatory movements of the axial shaft (bump stop) of the impact mechanism.
Will definitely interest: How to choose the right puncher. we guarantee it will be useful
Mechanical differences in rock drill designs
Most rock drills have a commutator motor. Its location can be horizontal or vertical. The first variant of engine placement is used in light, low-power vehicles. The second is in medium and heavy vehicles. Lightweight rotary hammers are convenient for household work, drilling small holes, lightly triggering old wall or floor coverings. They can work in hard-to-reach places, however, the vibration of this type of instrument, given its scheme of the percussion mechanism, is quite high. And their power is hardly enough to work on monolithic concrete.
Rotary hammers with a vertical engine are equipped with an anti-vibration system, as well as a crank-connecting rod percussion mechanism, which is more powerful and resistant to long-term loads. Impact power in some modifications of the heavy type can reach 20J, medium. 8. They are larger in size and weight of the tool, and are designed for particularly hard surfaces.
The principle of operation of the striking mechanism
The rotational movement of the engine drives one of the most important components of the rock drill, the percussion mechanism. The pneumatic system of this unit has 2 versions. with the use of an oscillating bearing or a crank mechanism combined with a gear part. When the shaft rotates, oscillatory rotations of the piston are created, pumping air into the working cylinder of the system. In this cylinder, due to the small space, compressed air pressure is created, which moves the ram and the firing pin. As a result of short-term impulse transitions of the piston and ram, these movements are converted into blows.
At idle, being not pressed against a hard surface, this mechanism shuts off automatically, no compression pressure is generated, and no shocks are made.
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Impact mode does not work in the punch
Forum / Tools and equipment / Impact mode does not work in the hammer drill
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October 18, 2014 at 11:01 PM
At one time, I also faced a similar misfortune, I had to change the piston and change the O-ring. In general, it is easier to give it to the workshop.
Striker and drummer
These parts are made from high strength steel. The striker rarely fails, but the bushing in which it moves absorbs some of the shock energy and collapses over time. Shrapnel jam the firing pin, and the hammer stops hitting.
The striker (“flying piston”) has a compression ring. When it wears out, part of the air passes into the gap between the cylinder in the barrel and the striker. The more wear and tear, the weaker the impact. The problem is solved by replacing the ring with a new one.
Sometimes the striking part of the “flying piston” breaks against the firing pin. This is usually the result of pressure on the rock drill while drilling holes. The drilling speed does not increase, but the load on the mechanism increases, which accelerates wear. Repair consists in chamfering on an emery machine or replacing a part.
Reasons for not hitting
At first glance, it seems that the striking mechanism has a simple design, and there is nothing to break there. Load, dust and vibration gradually take their toll. Typically, the force of impact decreases as the mechanism wears out and eventually comes to naught. The sharp disappearance of the impact is due to the deformation or destruction of some parts.
Grease
Failure to change the grease can also be the reason for the lack of shock. Working with a hammer drill implies the presence of dust, which does not in the best way affect the properties of lubricants. Dust can clog the holes in the cylinder that allow air to circulate when the hammer is operating. The same effect is not excluded when using a grease that is too thick, not intended for rock drills.
Hammer hammer mechanism
Most modern rock drills have an electro-pneumatic impact mechanism. “Electro”. because the mechanics are driven by an electric motor, and “pneumatic” means that the firing pin striking the drill shank is driven by air.
- Gear wheel for transferring rotation from the engine
- “Drunk” bearing
- Piston
- Drummer (“flying piston”)
- Trunk
- Striker
- SDS cartridge
When the button is pressed, the engine transfers rotation to the shaft with the “drunken” bearing, which in turn drives the piston inside the barrel. When the piston moves forward, air pressure increases between it and the striker. The striker moves towards the striker and hits it. The striker transfers the impact energy to the drill. Then the piston moves in the opposite direction, creating a vacuum area in the barrel. Due to this, the striker returns to its original position, after which the whole cycle is repeated.
Most rock drills have two or three modes of operation:
- combined mode: impact and rotation of the drill;
- rotation lock mode: only the impact mechanism works;
- Impact blocking mode: the hammer drill can be used as a drill or mixer for preparing building mixtures.
Causes and possibilities of elimination of the problem when there is no hammer blow
When drilling holes with a hammer drill, the main factor is not the rotation of the drill, but the impact. Its strength determines both the drilling speed and the ability of the tool to cope with particularly hard building materials (concrete, granite, etc.).
Dust and constant stress on the tool adversely affect its performance. During operation, the impact force may noticeably decrease or disappear altogether.
How does a hammer drill work and why it “refuses” to hammer?
WHAT MAKES IT WORK #24 Automatic Center Punch with cut-away tubalcain
“Drunk” bearing
It is mounted on the shaft at an angle and drives the piston. If there is a depletion or destruction, the bearing must be replaced.
Mode switch
Mechanism parts can come out of the guide grooves. This may be due to deformation, wear, or frequent use of the tool in an incomplete mode. The malfunction is eliminated by installing parts in their places or replacing them with new ones.
Mode switch
Mechanism parts can come out of the guide grooves. This may be due to deformation, wear, or frequent use of the tool in an incomplete mode. The malfunction is eliminated by installing parts in their places or replacing them with new ones.
Why the punch does not hit
“Drunk” bearing
It is mounted on the shaft at an angle and drives the piston. If there is a depletion or destruction, the bearing must be replaced.
Reasons for not hitting
At first glance, it seems that the striking mechanism has a simple design, and there is nothing to break there. Load, dust and vibration gradually take their toll. Typically, the force of impact decreases as the mechanism wears out and eventually comes to naught. The sharp disappearance of the impact is due to the deformation or destruction of some parts.
Malfunction of the drilling mode in the hammer drill
In the list of the most common malfunctions of a power tool, a situation is invariably mentioned when a BlackDecker, Bosch, DeWALT or any other perforator does not work in drilling mode, but at the same time actively hammers the material being processed.
Effective impact is an important advantage of the rock drill, but without the rotation of the drill, it will be almost completely leveled. In this case, the functionality of the tool will be limited to short-term operations with a bit, lance, etc long-term operation in the “chiseling without drilling” mode will quickly lead to a breakdown of the mechanism.
Usually the simplest answer to the question is why, when switching to drilling, the hammer hammer hits, as in hammer mode. This is most likely caused by a breakdown of the mode switch. a rather vulnerable component of many types of power tools. Switch replacement or repair can be done quickly and cost-effectively.
It is possible to preliminarily determine why a hammer drill from Makita, Metabo, Interskol, etc. beats, but does not drill, by the sound: if you can clearly hear the hum of the engine, but there are no rotational movements, then, obviously, the problem lies in the jamming of the gearbox. Sometimes the teeth of the gears break off. the splintered fragments prevent them from turning.
Also among the most common reasons why I stopped drilling the perforator Elitech, Hammer, Hitachi, STANLEY, RYOBI, Skil and other brands, the specialists of the service centers “Udachnaya Tekhnika Service” call:
- wear of the teeth of the protective clutch. in this case, a characteristic “ratchet” sound will be heard;
- abrasion of the gear teeth between the engine shaft and the intermediate shaft;
- loosening of the conical spring holding the clutch;
- lack of fixation of the large shaft gear.
In any case, diagnostics will require disassembly of the body and the mechanical part of the instrument.
The masters of the Udachnaya Tekhnika Service SC will easily cope with this work, select the necessary spare parts from the company’s own warehouse, perform cleaning, lubrication, preventive checks and adjustments of other units. And all this. quickly, at a favorable price and with the provision of a quality guarantee of services!
Grease
Failure to change the grease can also be the reason for the lack of shock. Working with a hammer drill implies the presence of dust, which does not in the best way affect the properties of lubricants. Dust can clog the holes in the cylinder that allow air to circulate when the hammer is operating. The same effect is not excluded when using a grease that is too thick, not intended for rock drills.
Striker and drummer
These parts are made from high strength steel. The striker rarely fails, but the bushing in which it moves absorbs some of the shock energy and collapses over time. Shrapnel jam the firing pin, and the hammer stops hitting.
The striker (“flying piston”) has a compression ring. When it wears out, part of the air passes into the gap between the cylinder in the barrel and the striker. The more wear and tear, the weaker the impact. The problem is solved by replacing the ring with a new one.
Sometimes the striking part of the “flying piston” breaks against the firing pin. This is usually the result of pressure on the rock drill while drilling holes. The drilling speed does not increase, but the load on the mechanism increases, which accelerates wear. Repair consists in chamfering on an emery machine or replacing a part.