JP3794545B2 - Screwdriver bit for cross-recessed screw - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a driver bit that is suitably fitted in an engagement hole formed in a screw head. In particular, when a screw tightening resistance is applied at the time of screw tightening, a force in a direction in which the driver bit escapes from the engagement hole is provided. The present invention relates to a screwdriver bit for a cross-recessed screw that is prevented from being damaged and that is not damaged as much as possible.
[0002]
[Prior art]
A generally used screw 2 has a cross-shaped engagement hole 20 formed in the head 3, and as shown in FIGS. 6 and 7, the engagement hole 20 is formed radially from the axis. The engaging groove 22 is formed. The engagement groove 22 is wider on the surface side of the head 3 of the screw 2 and becomes narrower as it gets deeper. Further, the outer surface of the engagement groove 22 is inclined inward so that the distance from the axis becomes shorter as the depth of the groove becomes deeper, and the center of the engagement hole 20 has a conical hole shape. . Further, a surface connecting the engagement walls 23 of the four engagement grooves 22 constituting the engagement hole 20 is a projecting plane 21 projecting in the center direction. That is, the distance of the narrowest part b is slightly larger on the surface side of the head 3 than on the bottom side.
[0003]
On the other hand, the driver bit that engages with the engagement hole 20 formed in the head 3 of the screw is normally defined by JIS (Japanese Industrial Standards) B4633. The shape is as shown in FIG. That is, it has a cross-sectional similar shape so that it can be fitted into the engagement hole 20 having the engagement groove 22 formed in the head 3 of the screw 2, and the shaft is opposed to the engagement groove 22. A blade portion 110 is formed at a position extending radially from the center and spaced equally in the circumferential direction. The tip of the driver bit 101 has a conical shape, and the tip surface of the blade portion 110 is inclined so that the blade 112 gradually increases from the tip toward the rear. Further, the side wall 114 constituting the blade portion 110 is slightly thinner on the outer peripheral side than the base side in the cross section in the direction perpendicular to the axis of the driver bit 101, and the guide groove 113 formed between the blades 112 is The driver bit 101 is formed so as to gradually become shallower from the tip to the rear. The bottom surface of the guide groove 113 is a linear surface having a continuous inclined surface with a concave center side, which is a portion that contacts the protruding flat surface 21 between the engagement walls of the screw 2. The protruding plane 21 and the guide groove 113 of the driver bit maintain the biting action without backlash between the screw 2 and the driver bit 1.
[0004]
[Problems to be solved by the invention]
However, between the engagement hole of such a normal screw and the driver bit applied to this engagement hole firmly bite at the center of each other, but it is driven to the driver bit to screw this screw into the workpiece When it is rotated by applying force, the blade portion of the driver bit rotates slightly until it abuts against the engagement wall of the screw engagement groove. Therefore, the engagement groove between the tip of the driver bit and the engagement hole of the screw The driver bit is lifted with respect to the screw engaging wall, and the area receiving the driving force of the driver bit is reduced, and the screw engaging wall is correspondingly increased. The location that receives the concentration of is the center side. Thereby, the screw is easily damaged. In addition, the engagement wall of the engagement groove constituting the engagement hole of the screw is inclined so that the space on the head surface side is slightly widened, and the driver bit escapes from the engagement hole as the rotational force is applied. In order to prevent this, the thrust for pressing the driver bit against the screw needs to be applied. For this reason, if a work is a comparatively thin plate-like thing, this work will bend, and it has various problems, such as the beauty as a product being spoiled.
[0005]
An object of the present invention is to provide a driver bit that solves such problems and obtains a shape that matches the engagement groove of the screw and that reliably transmits the driving force.
[0006]
[Means for Solving the Problems]
The object of the present invention is defined by the JIS standard comprising a head 3 in which an engagement hole 20 having a cross-shaped engagement groove 22 is formed and a leg portion integrally formed with the head 3 and threaded . engaged with the engagement hole 20 of the screw 2 in the driver bit 1 for transmitting screwing drive force to the screw 2, the shaft of the blade portion 10 of the engageable sectional cross-shaped engagement hole 20 of the screw 2 At the base of the blade portion 10, the opposing side walls of the adjacent blade portions 10 are connected by arc-shaped connection grooves 13 formed by arcs having a radius R , and the side walls of the blade portions are The blade 2 has a surface parallel to the engagement wall 23 forming the engagement groove 22 of the engagement hole 20 of the screw 2 and is inserted into the engagement groove 22 of the engagement hole 20 so that the four blades come into contact with each other. The center of the engagement hole 20 of the screw 2 and the center of the blade portion 10 are respectively fitted in the four engagement grooves 22. On the other hand, when the circular arc is inserted into the engagement hole 20, the shape is along the corner formed by the projection plane 21 of the engagement hole 20, and the corner of the projection plane 21 and the connection groove This is achieved by providing a screwdriver bit for a cross-recessed screw having a configuration in which a gap is formed between the screwdriver bit and the screwdriver bit. Further, in addition to this configuration, the radius R of the connection groove is at least 0.33 mm or more, and the cross-recessed screw in which the side walls of the blade portions 10 adjacent to each other across the gap are connected to both ends of the connection groove 13. This can also be achieved by providing a driver bit for the device.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2, reference numeral 1 denotes a driver bit having a wing 10 having a cross-shaped cross section at the tip, which has a shaft shape, and gradually extends from the tip of the driver bit 1 to a cylindrical shaft portion 11. It is formed in the cone shape which inclines in the outer peripheral direction. The blade portion 10 is composed of four blades 12 formed at equal intervals in the circumferential direction and connection grooves 13 each having an arcuate cross section formed between the blades 12. The groove 13 is formed so as to gradually become shallower from the center side of the shaft toward the outer peripheral surface from the tip to the rear of the driver bit 1. The radius R of the arc-shaped connecting groove 13 is at least 0.33 mm as shown in FIG. 4, and the blade portion 10 of the driver bit 1 is a screw defined by the JIS standard as shown in FIG. When it is inserted into the engagement hole 20 formed in 2, the arcuate shape is formed along the corner formed by the projecting flat surface 21 thereof. Both ends of the connecting groove 13 are connected to the side wall 14 of the blade portion 10 in the tangential direction, and the thickness of the blade 12 is slightly reduced as the side wall 14 reaches the outer periphery of the shaft portion 11 of the driver bit 1. It is inclined to.
[0008]
The connecting groove 13 has a circular arc surface at the tip of the driver bit 1 that is shorter than the distance b of the narrowest portion between the projecting flat surfaces 21 facing each other across the center of the screw 2 shown in FIG. That is, it is located on the center side, and thereby, between the corner formed on the projecting flat surface 21 of the engagement hole 20 in the head 3 of the screw 2 and the connection groove 13 of the driver bit 1. A slight gap is formed in the. Further, both side walls 14 of the blade portion 10 are parallel surfaces inclined so as to follow the engagement walls 23 that constitute the four engagement grooves 22 of the screw 2. When inserted into the engagement hole 20 of the screw 2, the side walls 14 of the blade portion 10 and the engagement wall 23 of the engagement groove 22 are brought into contact with each other, and the engagement hole 20 of the screw 2 and the blade of the driver bit 1 are fitted. The centers of the portions 10 are coincident with each other, and the blade portions 10 and the engaging grooves 22 bite. In addition, since the connecting groove 13 is not in contact with the projecting flat surface 21 of the engagement hole 20, the driver bit 1 does not deviate from the center when the driver bit 1 rotates, and the driver bit 1 has a force to escape almost upward. Will not occur. As a result, a reliable tightening force is applied to the screw 2 even when little thrust is applied to the driver bit 1.
[0009]
In order to use such a driver bit 1 to tighten the screw 2 as shown in FIGS. 6 and 7 to a work (not shown), the tip of the driver bit 1 is inserted into the engagement hole 20 of the screw 2. When fitted, the blade portion 10 of the driver bit 1 has its tip inserted into the engagement hole 20 as shown in FIGS. 3 and 5, so that both side walls 14 of the blade portion 10 are engaged with the engagement wall 23 of the engagement groove 22. Will be in contact. At this time, since the connection groove 13 of the driver bit 1 is hardly in contact with the projecting flat surface 21 of the screw 2 as shown in FIG. 4, the blade portion 10 and the engagement groove 22 are surely fitted together. . As a result, a sufficient biting state is obtained between the screw 2 and the driver bit 1 and the centers of the two always coincide.
[0010]
On the other hand, when a driving force for tightening the screw 2 is applied to the driver bit 1 in this state, the driving force is transmitted from the blade portion 10 to the engaging wall 23 of the engaging groove 22 of the screw 2. At this time, the engagement wall 23 and the side wall 14 of the blade portion 10 are in surface contact with each other, so that a wide driving force transmission surface is obtained, and the screw 2 or the driver bit 1 is not damaged. For this reason, a predetermined tightening force is reliably applied to the screw 2, and the screw 2 is fastened to the workpiece.
[0011]
【The invention's effect】
As apparent from the embodiment described above, the present invention provides a screwdriver bit 1 for transmitting a screwing driving force to a screw 2 defined by the JIS standard comprising a head 3 and a leg portion having a thread. The blade portion 10 having a cross-shaped cross section that can be engaged with the engagement hole 20 of the screw 2 is formed at the tip of the shaft portion, and the side walls adjacent to each other at the base portion of the blade portion 10 are formed by arcs having a radius R. The connecting groove 13 is connected, and the side wall of the blade portion has a surface parallel to the engaging wall 23 forming the engaging groove 22 of the engaging hole 20 of the screw 2 and the engaging groove 22 of the engaging hole 20. And the four blades are fitted into the four engagement grooves 22 so that the center of the engagement hole 20 of the screw 2 and the center of the blade portion 10 coincide with each other. When the arc is inserted into the engagement hole 20, the projecting plane 2 of the engagement hole 20. In since the configuration and the cross headed screw driver bit of a gap between the corner and the connection groove 13 of and projecting plane 21 in a shape along the angle formed, screw defined in the usual JIS standard Between the engagement hole and the driver bit applied to the engagement hole, the engagement groove and the blade portion can be firmly fitted and bitten . In addition, even if there is a slight gap until the blade portion of the driver bit contacts the engagement wall of the screw engagement groove, and the idling of the screw bit is caused to idle, the engagement groove of the screw engagement hole The tip of the driver bit does not ride on the crossing line formed by the projecting plane, and therefore the driver bit does not lift up against the engagement wall of the screw. In addition, the area for receiving the driving force of the driver bit is not reduced, the driving force is not concentrated on one point, and the screw and the driver bit are not easily damaged. Moreover, it is not necessary to apply a large thrust to the driver bit in order to prevent the component force in the direction in which the driver bit tries to escape from the engagement hole, and even if the workpiece is a relatively thin plate, Deflection does not occur, and it can be avoided that the beauty of the product is impaired.
[0012]
Further, when the blade portion is inserted into the engagement groove, the four blades are brought into contact engagement with the four engagement grooves 22 so that the center of the engagement hole 20 of the screw 2 and the center of the blade portion 10 are aligned. Since these screws are made to coincide, even if they are rotated by applying a driving force to the driver bit in order to screw this screw into the workpiece, the driving force is transmitted evenly by mutual surface contact , and the driving force is generated without causing loss. It is reliably transmitted to the screw. Further, the radius R of the connection groove is at least not 0.33mm or more, since sandwiching this side wall of the blade part 10 that are adjacent to each other has been connected with the arc-shaped at both ends of the connection groove 13, there is no corner Therefore, the number of places where stress concentration occurs in the driver bit is reduced, and a specific effect such as providing a driver bit having a long life can be obtained.
[Brief description of the drawings]
FIG. 1 is a front view of a driver bit according to an embodiment of the present invention.
FIG. 2 is a side view of FIG.
FIG. 3 is a cross-sectional view of an essential part showing a fitting state of a driver bit and an engagement hole of a screw.
4 is an enlarged view of a main part of FIG. 3;
FIG. 5 is a longitudinal sectional view of a main part showing a fitting state between a blade part and an engaging groove.
FIG. 6 is a plan view of a screw head.
FIG. 7 is a cross-sectional view of the main part of the head of the screw.
FIG. 8 is a front view of a conventional driver bit.
9 is a side view of FIG. 8. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Driver bit 2 Screw 3 Head 10 Blade part 11 Shaft part 12 Blade 13 Connection groove 14 Side wall 20 Engagement hole 21 Projection plane 22 Engagement groove 23 Engagement wall

Claims (2)

The engagement of the screw 2 defined by the JIS standard comprising a head 3 having an engagement hole 20 having a cross-shaped engagement groove 22 and a leg portion integrally formed with the head 3 and having a thread. In the driver bit 1 that engages with the hole 20 and transmits the screwing driving force to the screw 2,
The blade portion 10 of the engageable sectional cross-shaped engagement hole 20 of the screw 2 formed on the tip of the shaft portion, at the base of the blade portion 10, the radius R of the opposed side walls of the blade portion 10 adjacent to each other Are connected by an arc-shaped connection groove 13 formed by an arc of the same, and the side wall of the blade has a plane parallel to the engagement wall 23 forming the engagement groove 22 of the engagement hole 20 of the screw 2 and is engaged. When inserted into the engagement groove 22 of the joint hole 20, the four blades are fitted into the four engagement grooves 22, respectively, and the center of the engagement hole 20 of the screw 2 and the center of the blade portion 10 are brought into contact with each other. On the other hand, when the circular arc is inserted into the engagement hole 20, the shape follows the corner formed by the projection plane 21 of the engagement hole 20 and is connected to the corner of the projection plane 21. A screwdriver bit for a screw with a cross hole, characterized in that a gap is formed between the groove 13 and the groove 13 . The radius R of the connection groove is at least 0.33 mm or more, and the side walls of the blade portions 10 adjacent to each other across the gap are connected to both ends of the connection groove 13 . Screwdriver bit for cross-recessed screw.

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