Phillips Recess

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Phillips screwdriver
Head of a Phillips screw
Phillips bits in sizes PH0, PH1, PH2 and PH3
a) slit   b) Phillips    c)  Pozidriv    d)  Torx    e)  Allen    f)  Robertson    g)  Tri-Wing    h)  Torq-Set    i) Spanner

Phillips-Recess (short: Phillips ) is a form of the cross- head drive for screws.

The drive was invented by J. P. Thompson and patented in 1933. The slotted screw in use up to that point posed a problem for the emerging automated , industrial production , since the alignment of tool and screw took too much time and slipping of the tool could damage the product. Although tool manufacturers believed at the time that they could not produce such screw heads in contrast to conventional slotted screws, Thompson was able to sell the patent to the Phillips-Screw company owned by Henry F. Phillips .

The profile received further improvements and today essentially corresponds to a patent by Phillips from 1934. The drive initially established itself primarily in the American automotive industry, but also in many other areas after the Second World War .

With the Phillips drive, the four flanks of the blade taper downwards. Because of this wedge of a Phillips screw form occurs when tightening an axial force ( "eng. On, which drives out the tip of the screwdriver from the screw head cam out "). This torque- limiting effect, which was used deliberately at the time, means that both the screwdriver and the screw head can be damaged - the screw wears out and, under certain circumstances, can no longer be removed or retightened. This problem has been reduced in the improved Pozidriv version : There the cross-slot flanks run plane-parallel. However, the non-parallel Phillips flanks result in self-centering that keeps the screw exactly in line with the driving tool due to the applied axial force, which is necessary for self-drilling screws, for example. For this reason, among other things, the Phillips profile is still justified.

The associated drives or screwdrivers are labeled PH for Phillips in combination with a number, ie PH 0, PH 1, PH 2 etc. For smaller drives, the names PH 00 and PH 000 are common with decreasing size ; occasionally there are also other spellings.

Profiled output

Some manufacturers offer drives with a ribbed or roughened profile, which increase the friction of the output in the drive and thus prevent it from being driven out. These are compatible with their respective Phillips recess counterparts. Wera markets such a system under the name Lasertip .

The Phillips Screw Company itself offers this as the ACR Ribbed Phillips Cruciform Drive System , the drives of the screws are marked ACR1, ACR2, ACR3, ACR4S and ACR4L, the screws themselves are standardized in 7 sizes (0 to 6), with several Variants share the ACR2 drive. In emergencies, screws with an ACR drive can also be loosened with a conventional PH output of the same size (e.g. ACR2 with PH2), but not non-destructively.

See also

Individual evidence

  1. ↑ Patent US2046837 : Means for uniting a screw with a driver. Registered July 3, 1934 , published July 7, 1936 , inventor: Henry F. Phillips. ‌
  2. ↑ a b http://www.phillips-screw.com/acr_phillips.php
  3. ↑ a b http://www-de.wera.de/lasertip.html?&L=0

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