Hammer Drill


Also found in: Dictionary, Wikipedia.

hammer drill

[′ham·ər ‚dril]
(mechanical engineering)
Any of three types of fast-cutting, compressed-air rock drills (drifter, sinker, and stoper) in which a hammer strikes rapid blows on a loosely held piston, and the bit remains against the rock in the bottom of the hole, rebounding slightly at each blow, but does not reciprocate.

Hammer Drill

 

a percussion boring machine for drilling blast holes (less frequently well holes). The hammer drill is usually a pneumatic machine; power drills with gasoline engines are seldom used. In the first hammer drills (mid-19th century) the cutter performed its operation with a piston (so-called piston drills). These were later replaced by drills of the hammer type, in which the piston strikes the drill shaft, to which a rock-crushing drill bit is fastened. The bit turns 10°-15° on each return stroke of the piston. (The rotation is transmitted from the piston to the drill by a swivel gear.) Hammer drills with independent rotation, in which the drill is turned by a special air compressor, have been developed. Piston motion is controlled by an air-distribution device that supplies consecutive charges of air to the front and rear cylinder cavities. The crushed rock is removed from the blast hole by water or compressed air.

Hammer drills are classified as follows: hand-held jack-hammers (light, medium, and heavy-duty), weighing 10-30 kg, which are held in the drill operators’ hands or are mounted on a pneumatic support during the drilling operation; core hammer drills, weighing 50-70 kg, which are mounted on mobile drilling rigs or on columns with an automatic power supply; and telescoping borehammers, weighing 30-40 kg, for drilling upward-directed blast holes.

Hammer drills are rated according to the energy of a single impacts A= mv2/2 (m is the piston mass, and v is the velocity before impact), the number of impacts per minute n, the air flow rate, and the mass of the drill. The most efficient hammer drills are those with higher impact energy and an n rating of up to 2,000 impacts per minute. High-frequency hammer drills with n ratings above 2,500 impacts per minute are used only when mounted on mobile drilling rigs or manipulators, owing to their excessive noise level (up to 120 decibels) and high vibrations. Vibration-damping handles and mufflers have been developed to lessen the harmful effects of the vibration and noise on the drill operators.

REFERENCES

Tekhnika bureniia pri razrabotke mestorozhdenii poleznykh iskopaemykh. Moscow, 1966.
Pnevmaticheskie ruchnye mashiny: Spravochnik. Leningrad, 1968.

B. N. KUTUZOV

hammer drill

A percussive-type pneumatically powered rock drill.
References in periodicals archive ?
The tools you'll need: Hammer, wood chisel and panel saw (to get the old window out); a brick trowel; pointing trowel; some string; a few masonry nails; a club hammer; a bolster (for cutting bricks); a hammer drill with a masonry bit; a shovel; a bucket; an area for knocking up mortar; a jointing tool, or a small piece of 15mm copper pipe; a soft brush - paint brush or dustpan brush will be fine; PPE Gloves, and goggles.
A FAIRLY heavy hammer drill that performs well and has a few unusual features.
Together with the company's specialty drilling hammer drill bits, Universal HDD has designed an advanced steering mechanism for drilling hammers.
This is a heavy-duty cordless rotary hammer drill with chisel action which sounds like it will make short work of any drilling tasks around the house.
Last weekend, a hammer drill, a transformer and drill bits were taken from a Ford Courier parked in Deansway, and a jigsaw, a battery drill, a hammer drill and a circular saw, all made by Pro Performance, went from a Ford Transit in Harmar Close.
Lester Gothard, a subcontractor with Goehrs Builders in Coldsprings, Texas, relies on a DeWalt 18-volt hammer drill for boring 2-inch holes into 3/8-inch concrete.
Twenty years on, the company invented the hammer drill, and, in 1966, followed with the invention of its patented S-automatic safety clutch which protects users from excessive back-twist torque.
KD162 hammer drill, pounds 44.50; KC8452C cordless hammer drill, pounds 74.50; dust extractor, pounds 59.50.
Items stolen included a Voodoo Bantu mountain bike, a 40" Toshiba TV, an antique trumpet and various power tools including a Bosh multi-cutter and a DeWalt SDS hammer drill.
Austin Powder conducted a bore tracking test and the results showed a hole deviation rate with the MD5150C Top Hammer Drill that was within the desired range.
PS39.99 (each) 18V LI-ION DRILL AND DRIVER KIT DIY dads will be thrilled with this super value 18v cordless hammer drill and 18v cordless impact driver.
In this story, we'll give you the lowdown on the differences between a hammer drill and a rotary hammer, and help you figure out which tool is right for you.