Table grinding machines with which you can:
– sharpen the cutting edge of turning tools and drills;
– perform rough peeling of the surface from rust and deposits;
– chamfer before welding;
– remove burrs, scale, gates;
Present in private garages, repair shops, workshops of industrial enterprises.
If the tool has a dull blade, then not only does the energy cost increase during the operation of the power tool. The load on the engine increases, which overheats due to the need to increase efforts to overcome friction; increased vibration; the accuracy of all processing parameters is violated.
Effective processing, except for the grinding machine, there is nothing to perform. It is possible to chamfer with a file, but it is not rational to produce large metal removal.
The disk of the 125th angle grinder rotates at a speed of 11,000 rpm and upon contact with the metal of the edge of the cutting tool, it will be burned with a loss of hardness. Adjusting the workpiece to size, when removing the width of several centimeters, with an angle grinder, is inconvenient: the thickness of the grinding wheel is only 6 mm.
Actions with not heavy and small-sized parts are obtained more precisely when holding them in hands and leading to a grinding machine than when lowering a power tool on them.
The main parts of the design.
The electric sharpening motor is located horizontally and is enclosed in a cast aluminum or cast-iron casing. The stator is located in the central part, which is pulled together with studs with side covers.
Grinding wheels of a direct profile of different characteristics (coarse-grained for coarse removal and fine-grained for fine-tuning to size) mounted on the rotor shaft and hidden on ¾ in the protective casing act as accessories. On it, handcuffs for stopping blanks and protective screens are fixed.
The grinding head of the bench grinder rests on a stand with holes for mounting on a work bench. The control is performed by a button on the front panel, usually in a soft dust cover, like the Sthor 79206.
Since the motors are mainly asynchronous, there is no adjustment for rotation on them. The exception is small sharpeners with a flexible shaft and accessories with a diameter of 75 mm, such as Vega VBG 200.
Under the case, drawers for accessories, like the JET JSSG-10, or a coolant tank, like the Makita GB801, can be located.
Illumination of the working area is carried out by an incandescent lamp or LEDs, at Interskol T-125/120 there are 6 of them, in the lid on a flexible rod. Less often, luminaires are made in the form of overlays on casings, this design allows you to direct the light beam clearly at the end of the abrasive disk, at the place where the equipment touches.
Workshop and garage grinding machine or industrial?
Conventionally, all models can be divided into two groups:
– Desktop performance. With circles from 75 to 200 mm for machining small parts, cast aluminum housing, single-phase motor.
– Industrial electric sharpeners with grinding discs of 250, 300, 350, 400 mm, three-phase motors and a cast-iron floor construction that absorb vibration well. The weight of the machines can exceed 100 kg, for example, the weight TSh2 2 130 kg, and the installation is carried out permanently on an individual foundation anchor.
Control is carried out by buttons or through a foot pedal.
Large models are more universal: tool sharpening; grinding workpieces; stripping and peeling work of massive parts.
Even the best home grinders are not in constant operation. To protect against abrasive dust, their design is closed and after a 10-20 minute cycle, a break equal to or greater than the operating time is required. During this time, the motor cools down, the cooling of which occurs due to the large area of the casing.
Video: Sharpened Electric For Chainsaw Chains
Industrial models inside the head and bed housings have air vents for circulation of air flows, and the motor and bearing assemblies are protected through labyrinth seals.
Vibration when turning on the electric sharpener, caused by the beating of the outer diameter of the equipment, is eliminated with the help of dressing devices. On inexpensive grinders, vibration and jitter of the case may be due to inaccurate manufacturing of the most important component. spindle bearings.
To avoid this, on industrial versions they perform rotor balancing, remove all axial backlash, press in bearings of high accuracy class. Such measures reduce the end runout of the snap to 0.03. 0.05 mm.
Handicrafts of an electric sharpener.
When sharpening ink marks on metal and punch, resuming the cutting properties of chisels, cutters, knives, their cutting edge, relative to the circle, is positioned so that its rotation is directed under it.
The movement of the circles creates powerful air currents that cool the blade and prevent the steel from releasing and changing its hardness and mechanical properties. However, the location of the drill, chisel or planer knife towards the oncoming abrasive surface can provoke its tilt to the side of the worker.
Therefore, the sharpened tool rests on the desktop of the grinder and smoothly leads to a rotating disk, removing the load from the hands and getting a rigid base for fixing the angle of impact.
Emphasis for workpieces on grinding machines differ in area and thickness; execution (stamped steel as in BauMaster BG-60150 or cast part as in Scheppach BG 200); the ability to tilt; the presence of a scale of adjustment values.
For any electric sharpener, the handrail should have a horizontal stroke, to the end of the abrasive wheel, to reduce to 2-3 mm the gap, which is constantly increasing when it is worn.
If this distance is not reduced, the workpiece may fail, be caught in the gap by the equipment, wedge in it and cause a circle to break.
It consists of two sidewalls (one with a convex center to create space from the clamping nut) and a strip between them, tightened by screws. Fastens to the case, serves for safety of operation and on шли closes a grinding disk.
A support table and a protective screen are attached to the casing.
The outer sidewall is removed, freeing access to the nut to change the circle and clean the internal surfaces of adhering debris.
Stationary floor grinding machines in the lower part of the casing have a pipe for removing waste through an exhaust system.
Protective shields against sparks in the turning zone.
When the tool is rotated and in contact with the workpiece to be processed, the following people fly out onto the worker: breakaway abrasive, sparks and shavings. In addition, a disk moving at a speed of 1,500 to 3,000 rpm, under the influence of centrifugal force, can be torn to pieces.
To protect against this and protect the user from open parts, protective screens are installed.
On low-cost household electric ejector, such as Dnipro-M TE-32/25, this is a transparent plastic plate. On professional modifications, like the Makita GB602 it is shockproof glass, in the center of which a magnifying magnifier can be located.
When raising, the protective screen presses and lowers the motor trip switch, stopping its operation.
The execution of the unit should provide a convenient overview. It can be unregulated (rise and fall to a fixed position) and adjustable in height (fixing the angle of inclination occurs when tightening the thumb screw).
Tooling for grinding machines.
Grinding discs differ:
Outer diameter: 75, 100, 125, 150, 175, 200, 250, 300, 350 and 400 mm.
By case thickness: 10, 16, 20, 25, 40 mm.
The size of the internal, mounting on the spindle, holes: 10, 12.7, 16, 20, 32, 76, 127, etc.
Other features: composition, binder, size of abrasive, etc.
The motor parameters depend on the diameter of the circle, which means the total weight, size and price of the electric sharpener. But not only stones are installed on it. For polishing apply felt and felt equipment. The machining of shaped surfaces and grinding is done with rubber vulcanite discs interspersed with abrasive components. Dust-free deburring is convenient with wire brushes with high bristle density
If the shaft diameter is less than the fit of the circle, two adapters are used (steel adapter rings: from 12.7 to 32 mm; from 20 to 32 mm, etc.).
Parameters of the electric motor.
Most models have a stone rotation speed of about 3000 rpm.
For low-speed sharpening machines for cutting tools, with fine-grained and leather disc as in JET JSSG-8-M, from 90 to 200; small electro-loaders with a flexible shaft and a collector motor have an indicator from 1 to 9900 rpm.
Power ranges from 120 watts to 2.2 kW. When choosing a device for guiding the cutting edge, it does not play the same value as when peeling. Often a locksmith reinforces the workpiece clamp while trying to remove more metal. At this moment, the speed may drop to a complete stop. The speed of work is reduced and the electric motor suffers when heated, so a margin of power is needed.