| 摘要 |
A cross-head screw has a depression 12 formed in the end of the screw, and the depression is formed by superimposing two holes 14 in the form of equilateral triangles, which both have curved angles 13, and are arranged coaxially with a 60-degree phase offset around the axis of the screw. The depression thus has six notches 15 alternating with six drive partitions 16 with side walls 16a, which extend parallel with the axis, and the inner ridge of the partition is a conically curved grip wall 18, which slopes inwards towards the bottom 17 of the depression 12. The cross-sectional area A of the notch 5 is greater than the cross-sectional area B of each partition. The tip 25 of a screw-driver has six drive partitions 27 conforming to the notches 15, and six valleys 28, which are each located between the adjoining drive partitions and correspond to the drive partitions 16 in the depression 12, so that a gripping action is produced between the depression and the tip, the drive partitions can be reinforced and any conventional torx screw tip can be used with the screw-driver. <IMAGE>
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