How to Test Punch Impact Strength
All about your favorite breed and more
DIY punch repair
The first maintenance tool for the Sparky bpr 261e
I decided to conduct the first MOT to my perf. Purchased in 2006 and since then has not been cleaned and not smeared.
Of course, it was also not used at construction sites, everything was like the little things, home repairs and small electric coaches for mounting electricians.
There was a lot of dirt from el. engine. The grease in the gearbox is black, but it was.
Gearbox parts are not worn. Brushes in normal residue, collector without wear.
I like this perf in that the impact power of his 3.1 J
Power Consumption. 820 W
Max. idle speed. 1300 rpm
Max. shock frequency. 5440 bpm
Maximum torque. 30 Nm
Max. drilling diameter (concrete). 26 mm
Functions and Features
3 operating modes. drilling, drilling with impact, and just impact.
There is a reverse safety clutch
Weight. 2.7 kg
I disassembled and assembled using the video from YouTube and one scheme.
Link to video
who needs more I think I’ll find it myself, and I think very few people need it, the perf is old and few have it. Although the Interskol puncher has the same gearbox and some others have exactly the same thing.
If you have questions about the punch and its analysis, ask.
In the case, I cut out (removed) the bottom substrate for the punch, because apart from it you can’t put anything else and add. the pen had to be removed.
Whatever he was hanging around, he put a couple of thick pieces of polyethylene foam in empty places.
In makita, they immediately do normal cases.
DIY punch repair
For drilling holes in various materials, breaking walls, drilling rocks and roads, a perforator is designed. The tool is used under heavy loads and eventually malfunctions. You can replace the failed hammer with an inexpensive Chinese model. But if you have a branded tool, then it is a pity to throw it away. In order not to give half the cost of a punch for troubleshooting, you can do it yourself. Not a single repair is complete without studying the device structure and the procedure for disassembling it.
Types of rotary hammers
Hammers have several classifications. This is due to the different areas of application of the tool.
The number of modes can be from one to three:
drilling. The punch works in drill mode;
hammer drilling. You can make holes in brick and concrete;
jackhammer, that is, a blow without drilling.
Punch Drive Types:
electric. Network connection or battery operation;
Rotary hammer with battery
pneumatic. Such rotary hammers are used where the presence of electricity is dangerous due to fire or explosion. And in conditions of a large amount of water, where a short circuit may occur, for example, when eliminating the accident;
petrol. The tool is used in the repair and construction of roads, mining. Mostly as a jackhammer.
lungs. 2-4 kg. Power 400–700 watts. Used in everyday life;
medium. About 5 kg. Power 700–1200 watts. Professional
Types of cartridges used in rotary hammers:
SDS is installed on light and medium perforators for working with drills up to 20 mm;
SDS max is used for drills over 20 mm, therefore they are installed on heavy perforators with high power.
Classification by engine location:
simple or horizontal engine. Such rotary hammers have less weight and dimensions;
barrel or vertical engine. powerful rotary hammers.
Rotary hammer device
Regardless of the functions and designs, rotary hammers have similar basic elements.
Simple rotary hammer with network drive
Simple rotary hammer device
A barrel punch has the same basic components.
The device of a barrel punch with a network drive
The barrel punch has the same main components
The percussion hammer mechanism can be made in two versions:
- shock mechanism with a swinging bearing;
Swing Bearing Mechanism
crank shock mechanism.
A swinging bearing is also called drunk. Such a mechanism is used in light and medium perforators.
Impact drunk bearing mechanism
A crank mechanism is used in heavy rotary hammers.
Crank-hammer percussion mechanism
How to disassemble a punch
Disassemble the hammer drill in sequence. Inspect all parts carefully. Even if you are looking for a problem in one node, you can find damaged parts in other nodes. When disassembling the tool, clean the housing from dust and dirty grease.
How to disassemble a cartridge and pull out a stuck snap
Start by disassembling the cartridge so that it does not interfere with the removal of the gear housing.
- Remove rubber boot 1, circlip 2 and plastic boot 3.
Next, be careful, as there is a ball in the grooves of the sleeve under the locking washer 4. He can pop out.
Ball groove bush
If a drill or other equipment is not pulled out of the cartridge, there are two options for solving this problem:
- grip the snap in a vice. Slightly staggering the punch, pull it towards you;
- grip the hammer with rubber gaskets to prevent damage to the plastic case. Clamp the end of the tool with a gas wrench. Use a hammer to tap on the key in the direction of the tool axis.
The second option is used as a last resort. If after several strokes the drill or chisel could not be pulled out, discontinue. You may damage the punch. Disassemble the chuck and gearbox. With a punch, try to knock out the snap. After this procedure, most likely, you need to replace the raster sleeve. To avoid further such a problem, lubricate the end of the tool.
How to remove a stuck drill from a drill chuck
In some models of rotary hammers, the switch is removed by turning to the extreme right position, in others. to the far left. Consider the extreme right position.
- Put the mode switch on the beat. If there is no punch mode, a punch with drilling.
Pry the switch with a screwdriver
Analysis of the electric part of the punch
- Unscrew and remove the back cover.
- Turn off bolts of fastening of a power cord.
- Remove the button and wires from their grooves.
Analysis of the mechanical part of the punch
- Remove the plastic gear housing. You will see an aluminum case with a drunk bearing inserted into it, an intermediate shaft, a raster sleeve.
Raster sleeve and drunk bearing
Helical gear removal
To remove the spur gear, remove the snap ring and spring at the other end of the shaft.
Spur gear removal
Remove the sleeve from the sleeve.
The raster sleeve removed from the sleeve
Sleeve with a striker
How to assemble a hammer drill
Assembly is carried out in blocks. First, assemble the small parts into blocks, and then connect them.
- Insert the ball bearing and sleeve into the aluminum gear housing.
- Put elastic on the body. It prevents the flow of grease.
- Connect the raster sleeve to the sleeve.
- Lubricate the drunken bearing and gears liberally.
Gearbox after cleaning and lubrication
Hole in which to insert a screwdriver
Put on the back cover
Before installing the shift button with a screwdriver, slide the shift bracket in the punch case. So that the pin that is on the switch gets between two metal staple guides.
Setting the mode switch
Take the multimeter, put it into dialing mode and start the test with the power cord.
- Connect one probe to the end of the plug, the other to the pins on the other end of the wire. When connecting to one of the contacts there should be a sound signal. Do the same with the other end of the plug.
- Check the power button on the contacts with the power cord and with the stator. Press the trigger button.
- Check reverse contacts.
- Connect the probes to the brushes to check contact through the anchor.
- Connect the probes to the stator wires and ring them.
- If the stator or brushes do not ring, and the buttons and power cord are working, go to the diagnostics of the collector and motor windings.
Diagnostics of wires and punch buttons with a multimeter
At the anchor, first inspect the collector and winding. If the wiring is melted, a burnt insulating varnish will leave black marks or a specific smell. You can see bent and wrinkled turns or conductive particles, for example, solder residues. These particles cause a short circuit between the turns. Collector Damage: Raised, worn, or burnt plates.
Diagnose with a multimeter:
put a resistance of 200 ohms. Connect the test leads to two adjacent collector plates. If the resistance is the same between all adjacent plates, then the winding is working. If the resistance is less than 1 ohm and very close to zero, there is a short circuit between the turns. If the resistance is above the average two or more times, then there is a break in the turns of the winding. Sometimes, at a break, the resistance is so great that the device goes off scale. On an analog multimeter, the arrow will go all the way to the right. But on digital it will not show anything;
Checking the integrity of the armature winding
determination of breakdown to mass. Put the maximum resistance on the scale of the device. Depending on the tester, it can be from 2 MΩ to 200 MΩ. Connect one probe to the shaft, and the other to each plate in turn. In the absence of faults, the resistance should be zero;
do the same with the rotor. Connect one probe to the iron body of the rotor, and move the other along the plates.
Definitions of winding closure with rotor housing
An anchor can be saved if the balance is not disturbed. If during the operation of the device an intermittent hum is heard and there is a strong vibration, then this is an imbalance. Such an anchor must be replaced. And you can repair the winding and collector. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound. Worn and badly damaged lamellas to grind, grow or solder. In addition, do not undertake to repair the anchor if you are unsure of your capabilities. It is better to replace it or take it to a workshop for repair.
Checking the performance of the stator with a multimeter:
set the resistance mode to 200 ohms. Connect the test leads to the ends of one winding. A unity means an open, and zero means a short circuit between the turns. If it shows a resistance of more than 1.5 ohms, then check the second winding. Both windings should have approximately the same resistance;
Check for a breakdown to ground, that is, the winding is shorted to the metal housing of the stator. In the multimeter, set the maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal housing of the stator. The unit indicates the absence of breakdown.
Faults and their causes
Frequent malfunctions of the punch:
- does not turn on. Check electrical circuit;
- the punch does not hit. Breakdown in the percussion mechanism;
- the tool does not twist, does not drill. Reasons: anchor bearings, anchor gear, gear;
- the drill crashes, does not hold. Faulty cartridge or raster sleeve;
- sparking in the electrics enclosure. Reasons: violation of the insulation of the armature winding, wear of the brushes, collector, clogging of the brush holders;
- arcing in the area of the power button. Faulty button contacts or wires;
- the punch is heated. The reason is worn out brushes, short circuits of windings, poor gear lubrication;
- The hammer drill does not hold a cartridge. The snap ring or retainer was broken.
When disassembling the unit, carefully inspect the parts for cracks and chips.
Power Button Replacement
Before replacing, mark the wiring and contacts of the button so as not to confuse the connection procedure.
- To replace the button, just unscrew the screws of the contacts. But there may be buttons without cogs. Here, near the contacts, there are holes in which a needle or thin awl is inserted. Poke in the hole, push and pull the wires. Do not pull the wire; you may damage the button.
- The wires must be stripped and tinned.
- Take the old button and buy a similar one.
- On the new button, insert the awl into the hole, gently press and insert the wire. It will automatically snap into contacts.
Replacing a button with an awl
Brushes must be checked periodically. When one is worn by 40%, change both. Also, clean the brush holders.
- To remove the brushes, remove the back of the case. Fold back the springs that press the brushes.
Fold back the spring pressing brushes
Replacing and connecting the stator
- Remove the stator from the electrics housing. Put a new one in its place.
- Screw in the fixing bolts.
- Install the air intake.
- Proceed with connecting the windings. Connect the two ends of the different windings to each other and connect to the nearest brush. Connect the other two connected ends to the start button. Connect the wire from the second brush to the button.
There are several bearings in the hammer drill. To remove them, a puller is required. In some cases, it is necessary to remove the snap ring. If there is no puller, hang the shaft with the bearing and knock it out with a piece of wood. The bearing is planted using a tip from a polypropylene tube by tapping on it with a hammer.
Cartridges in rotary hammers change very simply. Remove the rubber boot, snap ring, plastic boot, washer, pressing balls, retaining plates, spring. In different models, the number of rings and plates is different. Put a new kit in their place.
Drunk Bearing Repair
Prepare a flat head screwdriver, clean rags, and gear lubricant recommended in the instructions.
- The bearing is held by the bracket. Disconnect it with a flat screwdriver.
- Remove the drunk bearing from the aluminum gear housing.
- Take out the needle bearing.
- Remove the gear and spring.
- Remove the plastic alignment from the spring.
- Replace defective parts.
- Take the aluminum gear case and clean it thoroughly with a dry cloth. Clean all parts too.
- Lubricate the bearing from the inside. Insert the needle bearing into it and also lubricate.
- Insert the gear, lubricate from the inside and insert the spring into it. Put on the centering.
- Lubricate the intermediate shaft and place the shift bracket on it. Install the shaft in a drunk bearing.
Drunk Bearing Assembly
Drunk bearing with sleeve
Repair raster bush and shock bolt
To disassemble the raster sleeve, it is necessary to compress the spring, remove the circlip and gear.
Raster sleeve assembly and without gear
Raster sleeve assembly and without gear
The impact bolt is repaired by replacing parts or changes completely if it falls apart.
- There are holes in the raster sleeve on both sides, in which the retaining ring is clearly visible. Pry off and slide the ring on both sides with a small flat-blade screwdriver.
Remove the ring and shake the impact bolt out of the sleeve.
Disassemble it into parts and check their integrity. Replace worn parts with new ones.
The sleeve wears out less often than the raster sleeve, but with frequent overheating of the tool, it also fails. Remove the raster bushing and sleeve from the aluminum gear housing. Put a new one in its place.
Worn and new brisk sleeve
Worn and new brisk sleeve
Features of repair of a keg
Repair barrel drills has the same principles as simple. The main difference in the design and the number of elements.
Remove the bottom cover of the case and see the plugs that need to be unscrewed.
The brushes have springs, so after removing the plugs, the springs will rise above the body, and you can easily pull out the brushes.
Replacing the brushes on the barrel drill
Impact mechanism and gear repair
The main difference between a barrel drill from a simple gearbox design. Some models have a shock mechanism with a drunk bearing.
Drunk barrel drills
Drunk barrel drills
But most punchers have a crank hammer.
Barrel punch with crank percussion mechanism
Crank-rod percussion mechanism at a barrel perforator
All gears and bearings must be checked and lubricated. Worn out change. To disassemble this design, you need to unscrew the bolts on the body. The barrel is knocked out of the body with a rubber mallet. Bearings are removed by a puller.
- After removing the barrel, you need to remove the raster sleeve with the striker. To do this, it is not necessary to disassemble the entire case.
How to remove the striker and the raster sleeve from the barrel puncher
Due to a malfunctioning hammer, the hammer stops beating.
Proper operation and maintenance of the hammer drill
To punch worked for a long time, you should follow some recommendations:
before fixing the tool, lubricate the shank with the tool specified in the instructions;
after work, clean the cartridge and accessories;
when working with concrete, take out a drill every 2 cm;
if you need to drill a large hole, use drills of different diameters, so as not to drill immediately with the largest drill;
with a large amount of work, take breaks so that the equipment cools down. During breaks you can clean the cartridge;
Regularly disassemble the cleaning and lubrication tool.
If the punch has any malfunction, read the instructions. Carefully inspect the tool. If you do not doubt yourself, make repairs yourself.
Video: How to Test Punch Impact Strength
The punch anchor is one of the crucial parts of this variety of household power tools. Unlike brush replacement, an anchor (rotor) malfunction is considered to be a technically more complex operation, the order of execution of which is determined by the design of the armature, as well as its useful life. Recall that, subject to all working conditions declared by the manufacturer, the rotor is replaced in the warranty workshops and only with branded spare parts.
Designs of anchors of different types of rock drill
An anchor is a rotating assembly of any induction motor. Given that during operation, the perforator experiences significant resistance to the material being destroyed with its help, rotor loads often reach extreme values. Sometimes they cause a significant decrease in the speed of the armature, which leads to an immediate failure of the electric motor.
The stability of the armature on the perforator from combustion is determined by its design. There are two types of perforator anchors:
- With a phase rotor.
- Squirrel cage rotor.
The short-circuited winding of the armature is formed by rods, which, when assembling the rotor, fit into the grooves of its core. In this case, the ends of the rods are connected using a special rotor ring. There are no moving contacts in such a design, which positively affects the durability of the node.
The disadvantage of an anchor of this design is the limited starting torque, which relative to the perforators requires restrictions on the intensity of use at the initial time after turning on the tool. Of course, it is impossible to constantly remember this, therefore, with inattentive use of the punch, the durability of the squirrel-cage motor will be low.
The problem is solved by installing squirrel-cage electric motors on all rotary hammers. The number of poles of the armature winding in this case fully corresponds to the same parameters for the stator, and the contacts of each phase are output to the external circuit using carbon-graphite brushes. Replacing brushes is a relatively simple process, which can (for equipment not under warranty) be carried out independently. In other cases, it is worth using the services of specialists. Often the price of this type of service is associated with the need for static and dynamic balancing of the anchor on the punch, for which special technology and equipment are used.
If you want to know about graphite brushes and their replacement, click on the link //proinstrumentinfo.ru/grafitovye-shhyotki-dlya-elektroinstrumenta-tonkosti-vybora/
How to check the performance of the punch anchor?
The sequence of this kind of routine maintenance is considered on the example of punchers from the Makita trademark, although there are no fundamental features for a similar tool from other manufacturers.
The need for replacing the anchor can occur when the punch does not give the required number of revolutions, the rotation of the rotor slows down sharply, characteristic sparking and cracking are observed.
The motor anchor consists of the following parts:
- a cylindrical element, which is formed by tightly connected stamped plates of electrical steel with a low silicon content, or of low-carbon steel Armco grades EA or EAA;
- the shaft on which the cylinder is mounted;
- phase coils, the windings of which are shifted relative to each other by an angle of 1200;
- slip rings mounted on the shaft, but electrically insulated both from it and from each other.
The anchor on the perforator is in mechanical contact with the gears of the perforator gearbox, therefore, for its final disconnection, it is enough to disengage the assembly from the worm that is on the rotor shaft.
The test begins with an external inspection of the collector plates: they should not have traces of soot and scratches. In this case, the engine brushes are considered operable and cannot be replaced.
Slow rotation of the armature on the perforator can be caused by contamination of the bearing dust washer, in which case it is removed from the housing and thoroughly rinsed with a technical solvent. Permissible fluids are usually listed by the manufacturer in the manual for the hammer drill. It is necessary to clean not only the outer, but also the inner surface of the protective washer.
Despite the fact that the external winding of the armature also has dust protection, it is worth inspecting the condition of the winding cords, and you can use a conventional vacuum cleaner to clean their surface.
Collector integrity is checked by a tester. According to the available electric circuit of the tool, all elements of the electric circuit of the punch are checked. If there is a short circuit, the anchor needs to be replaced. For a long-running tool, the price of the issue is determined by the model of the puncher: it is possible that the warranty workshop does not accept punchers of a certain brand for repair, and you will have to send a request for the required model of anchor to the manufacturer’s warehouses.
If the unstable operation of the perforator was caused only by contamination of its moving parts, then after thorough cleaning, the assembly of the assembly is carried out in the reverse order. In this case, it is necessary to ensure that the contact of the gearing with the worm of the gearbox is complete, and the dust ring completely covers the outer bearing housing.
Repair or replacement? The choice is yours!
A home master, experienced in electrical engineering issues, is quite capable of repairing the anchor on a punch with his own hands. Start work by identifying a malfunction. In the event of a break or short circuit of the turns of the armature winding, the cause of the “silence” of the punch or the slow rotation of its rotor (which is accompanied by intense sparking around the entire perimeter) is easily established by the tester. Sparking, as well as an attempt to rotate the punch armature in different directions, is a consequence of the closure of part of the turns in the winding. If the sparking is in the nature of a single, but long spark, then the cause is a broken wire or poor contact with the collector itself.
When checking, it is also worth checking the possibility of breakdown on the armature body. When measuring the values of the actual resistance, the obtained values should not be less than a few Ohms.
When developing a punch bearing, a significant imbalance in the axis of rotation of the armature is possible during the operation of the punch. This malfunction is diagnosed after a breakdown in the turns of the winding is not installed. To do this, you need to connect the puncher to the rheostat, and gradually increase the voltage to nominal. If during the diagnosis the tone of the electric motor changes, and the armature vibrations increase, then balancing of the rotor is necessary.
Since the rewinding of the anchor at home is almost impossible, it is recommended to resort to the services of specialized workshops. The price of rewinding the anchor to the puncher for most models (from Bosch, DeWalt, Makita, etc.) depends on the power of the tool and its performance (household or professional). If the drive power does not exceed 1000 W, then the service will cost 1000. 1200 rubles, for a drive with power up to 1500 W. 1500. 1600 rubles, and for more powerful rotary hammers. up to 2500 rubles. Comprehensive repair services (for example, replacing a bearing) can cost 3500. 4000 rubles. In this case, fault diagnosis in most workshops is free.
In the event of a breakdown of the tool that helps in the construction, not everyone will want to go to the workshop for lack of money, time or because repairs can result in the cost of a new thing. Some people prefer to do everything on their own. If the puncher stopped working at the crucial moment to identify the cause and eliminate it, the tool should be disassembled.
Even when the punch is serviceable, it still needs preventive cleaning and the replacement of worn-out elements, which means that it must be periodically disassembled. The method of parsing a tool from different manufacturers is approximately similar, but may differ in some nuances. One of the most famous brands are Interskol, Energomash, Sturm, Bosch.
How to disassemble a Sturm rotary hammer or similar models? The sequence of actions is as follows:
- First of all, it is necessary to establish whether the cause of the breakdown on the surface is not covered. At the puncher, the plastic boot located on the cartridge very often becomes unusable. Because of this, stoppers are lost. To prevent this problem, long drills should be used during operation.
- If there are no external defects, then it is necessary to disassemble the tool. You need to start from the top node: first, the tip is removed from the rubber, then the lock washer, then the head and spring. At the end of the described steps, pull out the ball.
- When disassembling a tool, you need to be extremely careful, remember where all the details were extracted from and in what sequence. You should also put them where they won’t roll or get lost, otherwise you won’t be able to return the hammer to life. Now carefully move the housing and gearbox to the sides until a gap of 30-50 mm appears between them.
- Set the switch to the “punch with drilling” mode and remove it.
- Remove the housing from the gearbox.
The disassembled puncher looks like this:
This element of the perforator device is used to transmit rotation from the electric motor to the cartridge. Thanks to this, the shock mechanism comes into operation.
The design of the gearbox includes a set of gears of various shapes. cylindrical, bevel, worm. In addition to them, this unit is equipped with an electronic device that regulates the number of revolutions and the frequency of impacts, and requires periodic inspection, lubrication and replacement of worn parts.
Before disassembling the hammer drill gear, you must first disassemble the cartridge. This will be described below. Next, disconnect the lever that switches the modes, while helping yourself with a flat screwdriver.
Having penetrated the gearbox, carefully inspect such details as:
- gears, while paying close attention to the teeth;
If any element is worn, then replace it with a new one. If not, then you just need to thoroughly clean it with gasoline or white spirit.
How to disassemble a perforator cartridge
First you need to remove the cartridge. Before this, you need to determine its design. Types of cartridges:
1. Cam. the drill is inserted and fixed with a special key.
2. Collet. to replace the drill a key is not required, just turn the chuck.
The chucks on different perforators are fixed in different ways. sometimes with a screw shaft, sometimes with a spindle. In some cases, they can be easily removed, and in some it is necessary to use additional tools and make efforts. The removal process looks like this:
- loosen hold by gently tapping the screw head;
- unscrew it with a screwdriver;
- hold the chuck in a vise and scroll the spindle.
As for the disassembly method, it can be different for tools of different companies. Let’s consider below how to disassemble the bosch puncher, or rather, its cartridge.
- Slide off the plastic part and remove the rubber seal.
- Remove the retaining ring, helping yourself with a screwdriver.
- Unscrew the lock washer.
- After removing the puck, another ring enters the field of view. It is possible to remove it by prying with a screwdriver and turning.
- This is followed by a collet clamp, which includes a spring, ball, washer. First remove the ball, then the rest of the parts.
The cartridge, as well as the gearbox, is disassembled not only for repair, but also for routine inspection and lubrication. After the necessary actions are carried out, you need to carefully assemble all the nodes using the above instructions, only in the direction from the last point to the first.
Why do punchers break?
The design of the hammer, like any other tool, includes mechanical and electrical parts. The most common electrical problems to be self-resolved include the following:
- breakdown of the start button;
- wear of graphite brushes.
To eliminate engine malfunctions, such as broken anchors, open windings, etc., special knowledge and skills are needed, which not everyone has.
Extraneous sounds, a large number of sparks inside the case, and the smell of burnt plastic can be harbingers of tool breakdowns. When they appear, you must immediately check the hammer for worn parts, because if you continue to operate it further, the engine may break down, and its repair will be much more complicated and expensive.
If there is no breakdown and everything is in order, the tool owner should still know how to disassemble the Energomash rotary hammer. The fact is that malfunctions can create dust, dirt, solid particles that clog the case from the inside and interfere with the movement of moving parts. All this garbage should first be cleaned with a dry brush, and then wipe the inside with a cloth moistened with white spirit to remove residues.
How to disassemble a puncher, video:
Different models of rotary hammers have design features that distinguish them from each other. depending on the manufacturer, power and functionality of the tool. However, despite these differences, all perforators contain the same components and systems that ensure their main function. The main components of the punch include: electric motor, gearbox, percussion mechanism and cartridge. In addition, there are auxiliary systems and mechanisms that expand the capabilities of rotary hammers or make their operation more convenient and safe. an anti-vibration system, a variolok device (Vario-Lock. a mechanism for fixing the tool in a certain position), a mechanism for limiting the depth of drilling, a dust removal system, mechanism for switching operating modes, etc.
Rotary hammer device
As motors in rotary hammers, as a rule, collector motors are used. Engines are located in two positions: horizontal and vertical.
Horizontal rotary hammer
Motor vertical rotary hammer
The horizontal layout is used, as a rule, in light perforators, vertical. in medium and heavy. However, there are exceptions. The heavy Metabo KHE 96 rotary hammer with a weight of almost 12 kg has a horizontal engine arrangement.
Metabo KHE 96 rotary hammer with horizontal engine
The horizontal layout tool is more compact and convenient for working in tight spaces. However, this design is characterized by increased shock load on the engine and somewhat worse cooling conditions.
The vertical layout provides better engine operating conditions (reduction of shock vibration and efficient cooling), as well as a wider amplitude of movement of the piston and hammer due to the possibility of using a crank mechanism with an increased piston stroke instead of a swinging bearing.
Rotary hammers with a vertical arrangement of the engine are capable of transferring more intensive work than models with a horizontal layout.
The most important assembly of the punch is the percussion mechanism, providing the main impact function of the tool. By type of execution, it can be electromechanical and electro-pneumatic. The latter type is used in the vast majority of models of modern rotary hammers. It allows you to get significant impact energy of the tool with minimal engine power.
There are two main versions of the shock electro-pneumatic mechanism. using a swinging (“drunk”) bearing or a crank mechanism. The first option is used for light and, in part, medium punch, the second. for medium and heavy.
The figure below shows a diagram of a lightweight rotary hammer. Its percussion mechanism consists of a swinging bearing, a piston, a ram and a hammer.
The device of the percussion hammer mechanism: 1. drunk bearing, 2. piston, 3. ram, 4. hammer (striker), 5. engine gear.
When the hammer is operated, rotation from the electric motor is transmitted to the inner sleeve of the swing bearing. At the same time, its outer sleeve, together with the perpendicular axis connected to the piston, oscillates. Between the piston and the ram there is an air space, which, due to the increased pressure and vacuum created in it alternately, causes the ram to repeat the oscillatory movements of the piston, striking the striker. The latter, in turn, hits the tool in the chuck. Thus, the energy of the electric motor is transformed into the shock energy of the tool.
The pneumatic impact mechanism is equipped with an idle self-shutdown function. At that time, when the tool (drill, drill, crown) is not pressed against the surface to be machined, the ram moves forward, opening a hole for air inlet and outlet in the housing. As a result of this, compression and rarefaction are not created in the working air cavity, the percussion mechanism is turned off, and the hammer works without impacts. When the tool is pressed onto the surface to be treated, the hole is blocked by a ram, compression occurs in the air cavity, and the percussion mechanism begins to function.
In medium and heavy rotary hammers with a vertical engine layout, the piston is driven by a crank mechanism. The increased amplitude of movement of the pistons contributes to a higher impact power, which for heavy perforators can reach 20 J. The operation of the percussion mechanism occurs similarly to that described above.
The device of the percussion hammer mechanism: 1. crank mechanism, 2. piston, 3. ram, 4. hammer (hammer), 5. nozzle (drill, chisel, etc.).
At the end of the article there is a video demonstrating the work of the percussion mechanism.
The figure below shows the device of a home-made puncher Progress PE-40/1050, 1050 W power with a vertical engine and a crank drive of the percussion mechanism. The rotation from the engine through the worm shaft is transmitted to the helical gear, on the shaft of which there is a crank, which drives the piston.
Motor vertical rotary hammer device
Hammer manufacturers are developing new anti-vibration systems. Vibration protection systems are divided into active and passive. Active anti-vibration systems (often labeled AVS) are installed only on powerful models. To dampen vibration, a simple principle is used: it is usually a shock-absorbing device, a counterweight to a spring, which takes on the recoil. True, this system is not able to completely absorb vibration, it only seriously reduces it.
Active anti-vibration system
Active anti-vibration system
At the end of the article there is a video demonstrating the operation of an active anti-vibration system.
In addition, the handle can also be responsible for damping vibration: from the bottom, it is attached to the body using a hinge, and from above through a spring mechanism. By passive anti-vibration system they mean ordinary rubber pads on the body, which also protect against slipping hands. However, we must admit that the sense of overlays is not too great.
Electric circuit punch
There are various ways to control the rotational speed of a rotary hammer motor. The engine speed can be adjusted by changing the pressure of the trigger, can also be selected on the dial before starting work. If the punch has a special circuit, the rotation speed will be unchanged at any load.
In general, the electric circuit of a perforator can vary significantly between different models, and in its simplest version it is similar to the electric circuit of an electric drill, which is described in detail in the article Drill design.
The puncher body is made of metal (usually aluminum or magnesium alloys) or impact-resistant plastic. Most often combine both. The metal case is stronger than the plastic one and removes heat well, providing effective tool cooling. According to the laws of physics, the air heats up during compression, so it is important to ensure the necessary cooling of the percussion mechanism when the hammer is operated. For this, part of the air from the fan wheel passes through the percussion mechanism. In this case, excessive heating of the punch body is prevented and a sufficient viscosity of the lubricant in the mechanism is maintained. To exclude a burn from a heated metal, various plastic linings are used.
One part of the punch body is made of metal, the other is made of plastic
Usually, punchers are equipped with a safety clutch, which serves to stop the rotation of the chuck when the tool is jammed in the hole. This condition is fraught with breakage of the nozzle or punch and injury to the worker due to a sharp jerk of the tool that occurs when the drill stops immediately. A safety clutch protects the tool motor from overloads. When the drill stops, the motor armature also stops, which leads to a sharp increase in the electric current in its winding. The clutch that disconnects the punch cartridge from the motor shaft does not allow the engine to burn out.
As safety in perforators, two types of couplings are used: friction and spring-cam. The first consists of disks in a normal state pressed against each other and transmitting torque. When the tool is jammed, the discs slip relative to each other, disconnecting the motor shaft from the cartridge with the nozzle. The friction clutch is used, for example, in Metabo models.
Many firms use spring-cam type safety clutches. They consist of two half-couplings having radially located protrusions and depressions (teeth) at the ends, which are combined in normal mode. The clamp of the coupling halves to each other is ensured by a spring. The principle of operation of the spring-cam clutch is based on the slip of the coupling halves relative to each other if the moment of resistance begins to exceed the compressive force of the spring. At the same time, a characteristic crack is heard, indicating that the nozzle is jammed.
It is believed that the spring-cam clutch is more reliable than the friction clutch, however, it also has a serious drawback. It lies in the fact that during operation, the tips of the teeth are rolled, which leads to the clutch engaging even when the nozzle does not jam, but only a lot of resistance arises. Some craftsmen cope with this problem by placing a washer 3-5 mm thick under the spring, which increases the compression force of the spring and, consequently, the moment of operation of the clutch. However, excessive “stiffness” of the coupling is also undesirable, because it makes the jerk of the tool too strong when jamming the nozzle, which can lead to injuries to the hands of people working with a perforator.
The rotary hammer gear transmits rotational motion from the engine to the chuck and drives the hammer mechanism of the tool. It consists of a set of cylindrical, bevel and worm gears. Most often, perforator gearboxes have a constant gear ratio. Regulation of the number of revolutions of the cartridge and the frequency of impacts is provided by an electronic controller. However, there are models with two-speed gearboxes.
Grease is used to lubricate the gearbox, which is filled into the gearbox during initial assembly and during maintenance or repair. at the moments when the hammer is disassembled.
Video demonstrating a punch device:
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We understand the device and the principle of the drill
During construction or finishing work, special tools cannot be dispensed with. One of the most popular and versatile is a hammer drill. Therefore, any person who uses this device needs to know its design and principle of operation.
How does the tool work?
On the market you can find a huge number of perforators with a variety of designs. But regardless of the many modifications of the device, they all consist of approximately the same components.
An electric drive is provided as a motor in the hammer drill. Commonly used collector type drives. In light models that are bought for use in domestic conditions, the engine is in a horizontal position. In medium and heavy, it is mounted vertically.
Devices with a horizontal drive are considered more compact and convenient when working in hard to reach places.
But this design has its drawbacks.
For example, due to the location features, the drive is poorly cooled; moreover, high loads act on its power component.
But devices with a vertical arrangement of the drive are cooled much better. In addition, their design involves a reduced level of shock vibration. Also, thanks to the vertical placement, it allows to give the piston a wide range of motion, which increases the amplitude of the hammer. This advantage is due to the fact that with a vertical arrangement, a crank mechanism is used. But in devices with a horizontal engine uses a rolling bearing. Thanks to this, rotary hammers with vertical motors have the ability to work much longer.
The percussion mechanism allows the punch to perform its main function (drilling). The tool uses two main types:
The first type of mechanism is used in most modern instrument models. Its main advantage is high impact energy with low power structure design. The electro-pneumatic mechanism is of two types. In the first, a rolling bearing is used (for light models), and in the second. a crank mechanism for heavy and medium models.
Among the elements of the shock mechanism, it is possible to distinguish a rolling bearing, ram, piston and striker.
During the start of operation, the impact force from the electric motor enters the inner race of the bearing.
The outer cage at the same time begins to produce oscillatory movements. The internal volume of air between the ram and the piston is alternately at high and low pressure. At this time, the ram repeats the movement behind the piston and hits the striker, which, in turn, strikes the nozzle in the cartridge.
The pneumatic operating mechanism allows the device to shut off during idle. This was made possible by moving the ram forward if there is no contact between the surface and the bit. During the movement of the ram, an opening is opened for connecting air from the piston chamber to the external environment.
The crank mechanism in rotary hammers works with high amplitude, which can significantly increase the impact power (up to 20 kJ). The mechanism itself operates almost in the same way as the previous one. The torsion impulse is transmitted from the worm shaft to the gear, and then the crank sends it to the percussion mechanism.
Companies are constantly developing new systems that will improve the mechanism and reduce the amount of vibration received by the tool. All existing technologies can be divided into two types:
An active vibration protection system is installed only on perforators with high power. They use a mechanism of a counterweight and a spring device. Such a technology cannot completely damp all generated vibrations, but it significantly lowers their level. Also, to perform this task, the device handle helps it, which is mounted on the punch body using a hinge and springs.
The passive vibration damping system uses rubber pads on the body. They also prevent slipping of hands when working with a hammer drill. Such a system is less efficient.
Wiring diagram and housing
Several methods are used to control the speed of rotation of the nozzles on a rotary hammer. Most often, for this, the master must change the force of pressing the start button. Some models use a knob to do this, which must be turned. The electrical circuits of different models are significantly different from each other. Most often, they are very similar to the device of an electric drill.
The puncher body is made of metal. Usually, an aluminum or magnesium alloy is used for its production. In lightweight punchers, the casing is made of shockproof plastic. Individual models can be made simultaneously from metal and plastic. Metal in such a device is also necessary for quick cooling of the system.
To effectively cool the entire system, air is used. It is delivered to the percussion mechanism using a fan located next to the electric motor. This design avoids overheating of the device. The powerful air flow allows you to maintain the required temperature of the entire drill and avoid injuries when working with it. In some models, the areas that heat up most are protected by plastic linings. In other devices for this, from one side the body is made of metal, and on the other from durable plastic.
To protect the device from breakage at the time of jamming of the cartridge, special couplings are used in perforators. It also helps prevent injuries during use and eliminates the risk of overloading the entire system. If the drill suddenly stops, the coupling protects the motor armature from stopping. It allows the perforator cartridge to detach from the shaft and prevents it from burning out.
Two types of couplings are most widely used for punch:
The first type is made from a group of disks connected to each other. When the cartridge stops, they slip, which helps the cartridge to separate from the other cartridge. The second mechanism has two half-couplings with special pits and elevations at the ends. They are attached to each other by means of a spring. The method of operation is the same as in the previous version. If the slip mechanism has worked, then the hammer produces a strong cracking of the teeth.
It has been found that the spring-cam system is safer for use in rotary hammers. But it has one significant minus. In the process, the ends of the protrusions on the coupling halves can be rolled, which leads to the involuntary inclusion of the mechanism without the need.
The gearbox is used to send a torsion pulse to the hammer drill. It also helps to operate the percussion mechanism. The gear case includes several types of gears. They have a constant gear ratio. Some types of tools include dual speed gearboxes. For reliability, grease is used, which is poured during the assembly of the device or during its repair. The number of revolutions of the punch is set using an electronic controller.
Most drills use three types of ammunition. They have the following construction:
The cam cartridge is also called the key. When using it, the nozzles are clamped using a key that allows you to compress and unclench the cams. In the keyless chuck, nozzles are fixed only with the help of hands. This design is single-coupled or double-coupled. They are used on rotary hammers with automatic shaft locking. The most common is the SDS system, it is included in the design of 90% of modern tools.
For the operation of the punch in its design provides three modes. Each of them is necessary to perform its own function.
To perform tasks in this mode, the device switch is set to the “drill” position. It is not necessary to press heavily on it, the pressing force of 5 kg will be sufficient. If the punch is used to drill holes, you can not turn on the reverse or shock mode, otherwise it will lead to breakage. To prevent the occurrence of such a situation, the tool has a “strike block” button.
To work in this mode, the switch is set to the position next to which a hammer with a drill is shown. Then the tool is brought to the working surface. Care must be taken to ensure that the drill does not skew or slip over the material. It is very easy to put pressure on the device.
To work with this mode, the switch is set to the position next to which the hammer is shown. When strobing, the tool is held firmly with both hands without strong pressure.
Working with a punch is not as complicated as it seems at first glance. When using it, you only need to clearly follow the instructions, paying attention to the individual structural nuances of the device. In order not to get injured and not break the tool, you should study the principle of its operation in advance and be careful.