When grinding small diameter holes, it takes a lot of high speeds rotation of the grinding spindles. So, when grinding holes with a diameter of 5 mm on a wheel with a diameter of 3 mm at a speed of only 30 m / s, the spindle must have a rotation speed of 200,000 rpm.
The use of belt drives to increase the speed is limited to the maximum allowable speeds belt. Belt-driven spindle speeds typically do not exceed 10,000 rpm, and the belts slip, fail quickly (after 150-300 hours) and create vibrations during operation.
High-speed pneumatic turbines are also not always suitable due to the very significant softness of their mechanical characteristics.
The problem of creating high-speed spindles has special meaning for production ball bearings where high quality internal and groove grinding is required. In this regard, numerous models of so-called electrospindles with rotation speeds of 12,000-50,000 rpm and more are used in the machine tool and ball bearing industries.
The electrospindle (fig. 1) is a grinding spindle with three bearings and an integrated squirrel-cage high-frequency motor. The motor rotor is placed between two spores at the end of the spindle opposite the grinding wheel.
Less commonly used designs with two or four supports. In the latter case, the motor shaft is connected to the spindle by means of a clutch.
The motor stator of the electrospindle is assembled from electrotechnical sheet steel. It has a bipolar winding. The motor rotor at rotation speeds up to 30-50 thousand rpm is also recruited from sheet steel and is supplied with a conventional short-circuited winding. Rotor diameter tends to be as small as possible.
At speeds greater than 50,000 rpm, due to significant steel losses, the stator is provided with a jacket with running water cooling. The rotors of engines designed to operate at such speeds are made in the form of a solid steel cylinder.
Of particular importance for the operation of electrospindles is the choice of the type of bearings. At rotation speeds up to -50,000 rpm, high-precision ball bearings are used. Such bearings must have a maximum clearance not exceeding 30 microns, which is achieved by proper assembly. The bearings are preloaded with calibrated springs. The calibration of preload springs for ball bearings and the selection of their fit must be given great attention.
At rotation speeds greater than 50,000 rpm, plain bearings work satisfactorily when they are intensively cooled by flowing oil supplied by a special pump. Sometimes the lubricant is supplied in a sprayed state.
High-frequency electrospindles for 100,000 rpm were also built on aerodynamic bearings (air-lubricated bearings).
In the production of high-frequency electric motors, very precise manufacturing is required. individual parts, dynamic balancing rotor, precise assembly and ensuring a strict uniformity of the gap between the stator and the rotor.
In connection with the above, the manufacture of electrospindles is carried out according to special technical conditions.
Fig.1. High frequency grinding electrospindle.
Coefficient useful action high-frequency motors are relatively small. This is due to the presence of increased losses in steel and friction losses in bearings.
The dimensions and weight of high-frequency motors are relatively small.
Rice. 2. Modern high frequency electrospindle
The use of electric spindles instead of belt-driven drives in the production of ball bearings increases labor productivity when working on internal grinding machines by at least 15-20%, sharply reduces rejection in taper, ovality and surface finish. The durability of grinding spindles increases by 5-10 times or more.
Of great interest is also the use of high-speed spindles when drilling holes with a diameter of less than 1 mm.
The frequency of the current supplying the high-frequency motor is selected depending on the required rotation speed n of the motor according to the formula
since p = 1.
So, at speeds of rotation of electrospindles of 12,000 and 120,000 rpm, frequencies of 200 and 2000 Hz are required, respectively.
To power high-frequency motors, special high-frequency generators were previously used. Now, for these purposes, static frequency converters on high-speed field-effect transistors are used.
On fig. 3 shows a three-phase current synchronous induction generator domestic production(type GIS-1). As can be seen from the drawing, the stator of such a generator has wide and narrow grooves. The excitation winding, the coils of which are placed in the wide slots of the stator, is fed with direct current. The magnetic field of these coils is closed through the teeth of the stator and the protrusions of the rotor, as shown in Fig. 3 dotted.
Rice. 3. High frequency induction current generator.
When the rotor rotates, the magnetic field, moving along with the protrusions of the rotor, crosses the turns of the winding alternating current, placed in the narrow slots of the stator, and induces a variable e in them. d.s. The frequency of this e. d.s. depends on the speed of rotation and the number of protrusions of the rotor. electromotive forces, induced by the same flux in the coils of the excitation winding, are mutually compensated due to the counter-connection of the coils.
The excitation winding is powered through a selenium rectifier connected to the AC mains. Both the stator and the rotor have magnetic cores made of sheet steel.
Generators of the described design are manufactured for rated power of 1.5; 3 and 6 kW and at frequencies of 400, 600, 800 and 1200 Hz. The rated rotation speed of synchronous generators is 3000 rpm.
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high speed enginesLSMV |
energy saving LSRPM engines |
for high temperatures LS, FLS |
corrosion-resistant motors FLS |
high speed asynchronous electric motors CPLS series
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The company's CPLS electric motors are specially designed for applications requiring a wide range of speed control and stringent weight and size requirements.
Data asynchronous motors squirrel-cage motors are well suited for weak field operation, providing the widest possible speed range that their mechanical design will allow.
Specifications:
ü Power range: 8.5 - 400 kW;
ü Rotation speed: 112 - 132 gauge up to 8000 rpm; 160 -200 size up to 6000 rpm;
ü Degree of protection: IP23, IP54;
ü Insulation class: F, H;
ü Cooling type: IC06, IC17, IC37;
ü Additional options: sensors feedback, temperature sensors PTC, PTO, relubricated bearings, brake, axial forced fan. Special motor shafts and flanges can be produced upon request.
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In terms of functionality, these machines can be compared with electric motors. direct current, so with brushless motors. The reduced moment of inertia of the rotor provides the motors with excellent dynamic performance.
Powered by frequency converters application of the rated torque (Mn) at the design point (n1) and compare them with the graphs.
fig.1 Graph of the nominal torque ( Mn) on the rotation speed ( n1)
for electric motors CPLS 112M, CPLS 112L, CPLS 132S, CPLS 132M, CPLS132L,
CPLS 160S, CPLS 160M, CPLS 160L, CPLS 200S, CPLS 200M, CPLS200L
Application area: control of winding and unwinding equipment, metallurgical industry, packaging industry, printing industry, cable production, extrusion equipment, etc.
When it comes to electric motors, there is no linear relationship between power, speed and voltage. Consider the industries in which high-voltage electric motors, high-speed motors, and high-power motors are used and how they differ.
Different types of high voltage electric motors
High-voltage electric motors are synchronous and asynchronous motors with a voltage of 3000, 6000, 6300, 6600 and 10000 V. Basically, these electric motors are used in industry: metallurgical, mining, machine tool building, chemical industries. Such electric motors are used in installations, smoke exhausters, mills, mills, screens, fans, etc.
Three-phase motors are designed to operate on alternating current with a frequency of 50 (60) Hz. To provide reliable operation use a stator winding of the "Monolith" or "Monolith-2" type with a heat resistance class of at least "B". The body of the electric motors is reinforced, which in turn reduces sound and vibration levels. Specific material consumption and energy performance are in the optimal ratio. High-voltage electric motors are also characterized by increased wear resistance.
The following electric motors are intended for the drive:
- mechanisms that do not require speed control - series A4, A4 12 and 13, DAZO4, DAZO4-12, DAZO4-13, AOD, AOVM, AOM, DAV;
- mechanisms with difficult starting conditions - series 2AOD;
- vertical hydraulic pumps- DVAN series.
High-speed electric motors and their features
Unlike high-voltage electric motors, high-speed ones are motors whose number of revolutions is 50 rpm or 3000 rpm. They have less weight, dimensions and even cost than slower counterparts of the same power.
To use engines with a frequency of up to 9000 rpm, it is necessary to use a mechanism with a large gear ratio, in particular, the wave transmission mechanism. It is simple, high reliability, accuracy and compactness.
The scope of high-speed engines is very wide. This includes electric motors for a hand-held engraver, and for a drill drill, and motors for the automotive and aviation industries.
Powerful electric motors
Ordinary three-phase electric motors rated power ranges from 120 W-315 kW. However, as practice shows, more powerful electric motor, the greater the height of the axis of the shaft. Therefore, it is customary to consider electric motors larger than 11 kW as powerful. The areas of application are also quite wide. In particular, crane and metallurgical. Electric motors high power also used in pumping units.
9000 rpm
They say it's the most cool car in history Lexus. And that his successor is obliged to jump through the roof, so as not to shame the legacy. They say that the sound of his motor can be listened to instead of music and instantly recognized even from a kilometer away. These enthusiastic fan epithets are about the LFA, the first full-fledged supercar from Lexus.
Dynamics Lexus LFA maybe not the most outstanding: acceleration to 100 km / h in 3.7 seconds, maximum speed- 326 km / h. But the car for its short life set a lot of records on the tracks (for example, at the Nurburgring) and "tacked" a lot of eminent rivals in drag battles. But the bright life of the LFA was short: in two years only 500 cars were made. No wonder fans are so excited for the sequel...
The car was built according to familiar canons: more aluminum (35%), more carbon (65%) ... But the hand-assembled engine turned out to be unique. Co-designed with Yamaha, the 4.8-liter V10, with its unusual 72-degree camber angle, was smaller than a conventional V8 and weighed less than a typical V6. Forged pistons, titanium connecting rods, valves and muffler, separate throttle for each cylinder, 560 hp. - and the "ceiling" at 9000 rpm! Moreover, Japanese engineers also separately tuned the "voice" of the engine, so that it was like that of Formula 1 cars. And it turned out: high revs LFA screams in a purely formulaic way!
Porsche 911 (991) GT3
Porsche 918 Spyder
9000 rpm
9150 rpm
IN big family Porsche, you will find several models whose engines seem to be about to go haywire from their own speed. The first is the 911 (991) GT3, produced since 2013. The six-cylinder boxer with a volume of 3.8 liters produces 475 hp. and spins up to 9000 rpm - thanks to almost weightless titanium connecting rods and forged pistons. Just because of the low-quality bolts of these very connecting rods, 785 cars fell under the revocable company. But every cloud has a silver lining: the company did not bother with replacing bolts - and simply put new engines on sports cars!
From November 2013 to June 2015, Porsche produced 918 Spyders in an edition of 918 units, each costing under a million euros. But, as you understand, the company had no problems with sales.
The second model, called the 918 Spyder, is already hybrid, three-engine and even crazier. The "heart" of the most-very Porsche in history is a 4.6-liter naturally aspirated V8 with a return of 608 Horse power and "cut-off" at 9150 rpm! And each axle here additionally turns its own electric motor. In total, it turned out 887 hp. and 1280 Nm of thrust (this is more than the more powerful LaFerrari), acceleration to 100 km / h in 2.5 seconds and a top speed of 351 km / h. Well, then - a minute of irresistible boasting: we managed to test the potential of this monster ourselves! you can read the text version of the test drive, and below we have posted the AutoVesti video for TV.
Ferrari LaFerrari
9250 rpm
The already legendary LaFerrari definitely deserves the title of the craziest Ferrari. The most powerful. The most advanced. And the very first hybrid model in the history of the company. From such blasphemy (exchange power clean energy atmospheric ICE on a cross between a goddess and an electric golf cart!) himself Enzo Ferrari probably rolled over in his grave. And at the same time, LaFerrari combined the difficult to combine.
Only 499 lucky people were able to buy a LaFerrari, paying over a million dollars for it.
Almost entirely molded from carbon fiber and equipped with carbon-ceramic brakes, it turned out to be airy light - only 1.2 tons of dry weight. active aerodynamics, active suspension, active rear "diff" ... And more than an active 800-horsepower motor that can spin up to 9250 rpm. But this is not some kind of motor with a cam, but a hefty atmospheric V12 with a volume of 6.2 liters! Plus a 163-horsepower electric motor built into the 7-speed "robot". At the output - 350 km / h "maximum speed" and acceleration to 100 km / h in about 2.5 seconds. And the LaFerrari not only drives crazy, it still sounds as crazy as a Ferrari should. If old Enzo had listened and tried, he would have forgiven and become proud...
10,000 rpm
Honda ate the dog on "twisting" motors - thanks to their motorcycle heritage! Many of you probably remember the crazy S2000 roadster with a 2-liter naturally aspirated engine that produced 240 hp. and spinning up to almost 9000 rpm. But who remembers the ideological ancestor of this machine?
The Honda S800 was produced from 1966 to 1970, making 11,536 units.
His name was S800. Lightweight, sleek and sporty two-seat roadster or coupe. Four cylinders, a working volume of only 0.8 liters. The motor gave out only 70 hp, but firstly, with it, the S800 became the first Honda, which accelerated to 160 km / h. And at the time it was the fastest in the world stock car with a motor up to 1 liter. And the engine itself accelerated to 10,000 rpm, and even with such a sound! It's funny that at the same time, the early S800s still combined very advanced in those years independent suspension in a circle - and chain drive rear drive wheels. Also a motorcycle heritage ...
