A drill is a device for drilling , countersinking or reaming , either as a machine tool or as a powered hand tool . The actual tool is usually a drill , sometimes a reamer or a countersink . The shaped elements produced with the drill are bores . In order to put the drill in the required rotary motion, the drill has a torque generator, usually an electric motor , and pneumatic drives are also common. In the time before electrical individual drives became established in use, drills driven by transmission (belt drive) were widespread in industry and trade .
The electric hand drill built by Wilhelm Emil Fein in 1895 was one of the first power tools.
The device is held and guided by hand while drilling . In addition to electric and pneumatic hand drills, there are also hand-operated devices such as the drill winch . To safely guide the machine at high torques, an additional handle can often be attached just before the drill chuck for the other hand. Often a depth stop can also be installed to limit the drilling depth. In the machine shown in the top picture, a switch can be used to switch between two gear gears in order to drill at low or high speed. Many devices also have a stepless electrical power controller (often called a "speed controller") with which the torque and speed can be influenced.
A hammer drill has a hammer mechanism (which can usually be switched off), which exerts short-stroke axial blows on the workpiece to be drilled via the drill head with a high number of blows. Many hand drills - designed as hammer drills - are equipped with a switchable, integrated hammer drill device.
The hammer mechanism almost always consists of ratchet teeth on the drill spindle. The effectiveness is only achieved through high pressure. System- related wear of the teeth occurs. A hammer drill is more suitable for frequent drilling in concrete.
Cordless drills (see also cordless tools ) are cordless hand-held (impact) drills. Their areas of application are mostly light work in wood, plastic and metal. Most cordless drills do not have a hammer mechanism, so they are not suitable for drilling into hard rock or concrete.
The hammer drill is a drill that is specialized for drilling in stone and concrete as well as for chiselling work. The number of blows here is significantly lower than with the impact drill, but the impact energy is much higher. In contrast to the impact drill, the blows are generated by a pneumatic hammer mechanism, which enables a higher impact energy. At the same time, the required holding force by the operator is lower than with a hammer drill with the same drilling capacity.
Bench drilling machines are single-spindle vertical drilling machines that are permanently mounted on work tables. The speed can usually be changed either continuously or by turning a V-belt. Depending on the design, there is also the option of attaching a drilling table to the column. The feed movement is mainly carried out manually using a lever.
Bench drilling machines are mainly available in two sizes:
- General purpose devices with properties that are on par with or slightly above large hand drills;
- small, fast-rotating platinum drilling machines (often at speeds up to 10,000 / min) mm for small bore diameter, usually a maximum. 3 Board drilling machines are often equipped with a permanently installed magnifying glass and lighting so that the small drill holes can be precisely set.
Column drilling machine and column drilling machine
Column drilling machines and column drilling machines are particularly suitable for handy workpieces. The machine consists of a foot, column or stand, drill table and drill head. The column or the stand serves as a guide for the drilling table , which is radially adjustable in height and, in the case of the column drilling machine, can be clamped . A machine vice is usually used to fasten the workpiece on the drilling table . A gear transmits the power of the motor to the drilling quill with drilling spindle and drill chuck. The drill quill can be moved vertically down towards the workpiece by turning a hand rim or by machine. The automatic feed can usually be set in several stages. The difference between column and column drilling machines lies in the design of the support. The pillar drilling machine has a rectangular stand with guides for the drilling table, also known as a desk-top drilling machine, with a linear guide , while the pillar drilling machine uses a round column as a guide, which the table holder completely encompasses.
A magnetic drill is a variant of the column drill. The machine is not held in a purely mechanical manner, rather it is attached to the magnetic workpiece to be processed, e.g. B. a steel beam held. In contrast to the hand drill, this enables more precise work without tilting with a higher torque.
Line drilling machine
Row drilling machines consist of several column drilling machines that serve a common drilling table. They can be used to carry out various operations such as drilling and countersinking on a workpiece in one setting. This enables particularly fast and economical work.
Radial drilling machine
Radial drilling machines are used for large and heavy workpieces. The drill head can be adjusted and clamped in all three dimensions, i.e. in height, radially and also lengthways. The drilling table is usually fixed and has T-slots for clamping the workpiece. The tool can be moved in the direction of the workpiece by operating a lever or using a machine.
Knothole boring machine
Knothole boring machines are mainly used in woodworking to drill out branches from boards and beams. They can be designed in stand construction or as a wall-mounted machine. As a rule, they have three to five drilling spindles, which are individually moved down using a lever mechanism and then returned to their original position by means of a spring. It is not possible to move the spindles relative to one another. A further development is the automatic knot patching machine, which automatically drills out the knot, injects glue and then presses in the tenon or dowel.
Core drilling machine
Core drills are devices that specialize in drilling into stone , concrete and masonry . Only diamond-set drill bits are used as drills . The core drilling machine is operated without impact and partly with water flushing for the purpose of cooling and removing the drilling dust. The holes made with this machine are very precise and leave a very smooth drilling edge. The diameter of the bores is around 8 mm to over 500 mm, with the speed decreasing as the size increases.
Special shapes without cutting, mechanical drills
There are (also) machines suitable for drilling in which no (metallic) drill is clamped as a cutting effector. Examples are the electron beam drilling machine (one of the first applications of electron beam material processing ), the ultrasonic drilling machine , but also laser cutting , plasma cutters or water jet cutting machines can "drill" holes.
→ Main article: drill chucks
The drilling tools are usually clamped in a drill chuck. A chuck wrench is required to tighten the geared chucks. With this type of drill chuck , the clamping jaws, which are guided in bores inside the receptacle, are moved back and forth by turning the external gear rim via a thread . Since the guides are not parallel to the axis of rotation, this causes a strongly reduced movement in the radial direction. This movement in the radial direction changes the size of the free space remaining between the clamping jaws. As a result, the tool inserted into the chuck is either clamped or released, depending on the direction of rotation. Due to its design, the key-type drill chuck cannot turn open even in counter-clockwise rotation. However, this can happen in some quick-release chucks that are constructed slightly differently. There are also quick-release chucks, which are constructed according to the functional principle of the key-type drill chuck, and quick-release chucks with an anti-twist lock are also manufactured for hand drills with counterclockwise rotation. Column drilling machines and larger devices, as well as many hand drills in the meantime, can often be equipped with various keyless chucks that enable safe clamping even without tools. Rotary hammers usually have some form of SDS coupling .
A Morse taper is used to hold the drill bit on upright and radial drilling machines . For bores with a diameter of less than 12 mm, a standard three-jaw chuck is usually inserted into the Morse taper. The clamping effect of a Morse taper is created by static friction. A so-called drive flap is used to remove the drill .
For drills used commercially, a regular safety check is required in accordance with the Industrial Safety Ordinance in conjunction with the guidelines of the employers' liability insurance association and the VDE regulations.
Wearing protective goggles is mandatory for commercial use and is also important for private use. Jewelry should be removed before starting work and long hair should be secured. Under no circumstances may gloves be worn (on non-hand-held drills), as they can get caught in the rotating elements of the machine and parts of the body (fingers, hand) can then be torn out.
It is also important to secure the workpiece against turning. A machine vise is useful for this with column drilling machines. If necessary, this can also be attached to the machine table using a clamp.