Impact drill
A hammer drill is a drill in which , in addition to the normal rotary movement, a vibration-like movement in the axial direction can be switched on. As a result, the machine can be used without "impact" for drilling in wood , metal , plastics and the like, with "impact" to drill into relatively solid materials such as bricks or lightweight concrete .
history
Robert Bosch designed the first concrete hammer drill in 1917. In 1953, the Otto Baier machine factory was the first to develop a functioning impact system for electric hand drills , but Metabo made the impact drill a mass product from 1957 onwards .
Working principle
The impact is generated mechanically and transmitted to the drill unsprung. On the drive shaft and in the housing of the machine in front of the bearing there is a helical toothed disc made of high-strength material. If the shaft rotates, it pushes the entire machine backwards until the edges of the toothed disks slide over one another. Then the machine beats forward with its entire weight, the impulse is transmitted to the drill chuck and finally to the drill. Since this impulse energy, which depends on the contact pressure of the machine operator, is very low, impact drills have a correspondingly high impact frequency with a high reaction force for the user.
The hammer drill achieves a significantly higher impact energy with a lower number of blows . How it works, however, is fundamentally different from that of the impact drill. With the hammer drill, the impact energy of a movable mass of the hammer mechanism (pneumatic or hydraulic) is resiliently hit on the axially movable drill , which transfers the energy to the drilling material.
Impact drills are produced with outputs of approx. 400 to approx. 1500 watts. Modern machines have a stepless speed control as well as right-left rotation . The key drill chucks that were used in the past are now largely replaced by keyless chucks that allow the drill bit to be changed without tools.
Individual evidence
- ↑ Hans-Joachim Braun : The 101 most important inventions in world history . 2nd, updated edition CH Beck, Munich 2007, ISBN 978-3-406-56466-6 , p. 10.
- ↑ Ralf Spicker: First electric hand drill . In: Bauhandwerk , No. 6/2011, accessed on September 18, 2015.