Phillips screw
Phillips- head screws are screws with cross-shaped slots for attaching the appropriate screwdriver . They have almost completely displaced slotted screws in industrial production.
Emergence
With increasing mass production in the 1920s and greater torques to be transmitted , the disadvantages of slotted screws became more apparent: the screwdriver takes a relatively long time to apply and if it slips, not only the screw but also the component is damaged. For this reason, J. P. Thompson developed the cross- head screw ( Phillips ) in the 1930s , with which the tool centers itself in the screw head. The main advantage is the optimized power transmission between screw and tool, because the power is not only transmitted with one slot, but now with two slots. The material stress was reduced by a factor of 2 and the approach for power transmission increased by a factor of 2.
A further development by Phillips in the 1960s resulted in the Pozidriv screws, which no longer have the disadvantage of axially driving out the tool.
Executions
Are widely used Pozidriv (PZ) - and Phillips (PH) screws.
It is important for the user to know and observe the structural differences in order to avoid damage to the screw head and the screwdriver.
The fine star lines on the screw head of the Pozidriv screws that emanate from the inner corners serve as an external distinguishing feature, which are not present on the Phillips screws.
| Phillips | Pozidriv |
|---|---|
 |
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In the case of screws with a Phillips cross recess, the flanks of the cross recess taper as the depth of the slot increases. In contrast, with Pozidriv screws, the deep flanks of the screw head are not conical, but parallel to one another.
| Frearson |
|---|
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So-called Frearson screws are still in use in the USA . The name goes back to the inventor John Frearson from Birmingham , who received a patent for it in 1857. Other names are "Type 2 recess" (according to ANSI standard) or "Reed & Prince" (after a former US manufacturer). Compared to the Phillips screw head, the flanks have a different angle (75 °) and are precisely cross-shaped. In addition, the screwdriver is pointed and not blunted. The main application is boat building.
| JIS screw |
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The Japanese JIS Phillips screws are special, they have different dimensions and angles than a Phillips screw. The Phillips tool will wind out of the screw head if too much torque is applied; the JIS, on the other hand, is designed in such a way that the wrench does not unscrew. It is an alternative to the Pozidriv system, which also prevents so-called cam-out.
There are other variants of Phillips screws:
Crossed-Slot, Lotus Head, Sel-O-Fit, French Recess (BNAE Bureau de Normalization de l'Aeronautique et de l'Espace; NFL22-070), ACR Phillips, Phillips II, Phillips Square-Driv, SupaDriv. However, these are less common and are mainly used in industrial assembly.
See also
References and comments
- ↑ Peter Thomas : Modern screw drives: The cross with the Phillips faz.net from January 6, 2013 [1]
- ↑ Vanished Tool Makes: Reed & Prince / Frearson
- ^ Reed & Prince or Frearson
- ↑ SPAX: Technical Lexicon. Retrieved October 15, 2019 .
- ↑ JIS screws on peterverdone.com, accessed November 5, 2016.