JPS585151B2 - Cutting edge of screw fastening tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the cutting edges of screw fastening tools such as drivers and electric drills used to screw in various types of screws.

In the past, various types of screws have been created, but the slots formed in the head of the screw are well known to include a slotted hole and a slotted slotted hole.

However, the cutting edge of the screw fastening tool such as a flathead screwdriver used for a slotted slotted screwdriver is shaped like a single letter, and if this cutting edge does not tightly engage with the slotted slotted hole, the cutting edge will be damaged. It may slip, crushing the slot or damaging the cutting edge itself.

In particular, when using an electric drill, if the cutting edge and the slotted slot are not perfectly aligned, the screw may fly off, or the cutting edge may slip, knocking over the screw and causing injury to your fingertips or other personal injury.

Furthermore, screws with Phillips slots have similar drawbacks, and in particular cannot be used unless the cross-shaped cutting edge matches the size of the Phillips slot.

In view of the above, the present invention has been developed by the applicant of the present invention to develop a novel structure which prevents the collapse of the slot and which can be used even if the cutting edge of a screwdriver or the like used does not tightly engage with the slot with less wear on the cutting edge. Although we have created a screw with a slotted hole and are now filing a patent application together with the present invention, it is our intention to provide a screw fastening tool such as a screwdriver that is optimal for use with such a screw. It is.

The embodiments of the present invention will be described below with reference to a screwdriver, but the present invention is not limited to this description (the present invention can be applied to the cutting edge of a screw fastening tool such as an electric drill).

First, to briefly explain the structure of the screw, the screw 1 shown in FIG. There is.

This groove hole 3 has three openings 7 having an arcuate surface 6 of at least approximately 1/2 or more in the center of the head 2, arranged in an approximately three-star shape, and has a shaft portion 5. A gently tapered portion 7a is formed toward the axial center, and a conically pointed sharp portion 8 is formed at the tip toward the axis.

Note that it is also possible to replace the tapered portion 7 with a vertical portion.

The cutting edge 10 of the driver 9 used in the slot 3 of such a screw 1 has at least one blade having a sharp tip 12 formed at the tip of the shaft part 11 so as to tightly engage with the slot 3. It is constructed in a Sanda conical shape with a circular arc surface 12a of /2 or more.

Therefore, if the sharp part 12 of the cutting edge 10 engages with the sharp part 8 of the slot 3, even if there is some play, the acting force will act on the sharp part 8 of the shaft core, so the cutting edge 10 will not slip. The screw 1 can be tightened without fail.

Furthermore, since the outer periphery of this cutting edge 10 has a circular arc surface, the slot 3
Even when engaged, there is little wear and can be used for a long time.

Next, the structure of the screw 13 shown in FIG. 6 will be explained.
At least approximately 1/2 inch in the center of the head 14 of this screw 13
Two openings 12 having two or more arcuate surfaces 15 are joined together to form a slot 16 approximately in the shape of a figure eight.
6 forms a gentle taper part 17 toward the shaft part 5, and also forms a sharp part 18 with a conical tip toward the shaft center, but this taper part 17 is not necessarily an essential requirement. Instead, it may be changed to a vertical section.

Therefore, the screw 13 provided with the slot 16 having such a configuration
In this case, the cutting edge 20 of the driver 19 has at least one sharp point 22 formed at the distal end of the shaft portion 21.
It is configured in a Sanda conical shape with a circular arc surface 22a of /2 or more.

In such a driver 19, if the sharp part 22 of the cutting edge 20 engages with the sharp part 18 of the slot 16,
Even if the outer periphery of the cutting edge 20 does not tightly engage the slot 16 and there is some play, the force acts on the sharp part 18 of the shaft core, so the cutting edge 20 will not slip and the screw 13 will be securely tightened. It spirals and screws in.

Furthermore, since the outer periphery of the cutting edge 20 is an arcuate surface, even if it engages with the slot 16, there is little wear and damage to the cutting edge 20 can be prevented.

As described above, in the present invention, since the force acts on the sharp part facing the axis of the slot, even if the cutting edge does not tightly engage with the slot and there is some play, the cutting edge will not slip. The screw can be threaded securely and screwed in.

Furthermore, since the engagement surface between the cutting edge and the slot is a circular arc, it suffers much less wear compared to conventional square cutting edges, and can withstand long-term use.

Note that it is also possible to make this cutting edge magnetic.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a driver according to the present invention, Fig. 2 is an enlarged explanatory view of the same, Fig. 3 is an explanatory view of the screw, and Fig. 4 is a perspective view of a driver according to another embodiment of the present invention. FIG. 5 is an enlarged explanatory view of the same, and FIG. 6 is an explanatory view of the screw. 10.20...Blade tip, 11.21...Shaft portion, 12.
22...Sharp part.

Claims (1)

[Claims] 1. The cutting edge of a tool for screw fastening, in which the cutting edge of the tip of the shaft part is configured in the shape of two or three cones having an arcuate surface of at least 1/2 or more with a pointed tip.