HK1036245B

HK1036245B - Combination of driver bit and screw

Info

Publication number: HK1036245B
Application number: HK01106825.7A
Authority: HK
Inventors: 户津胜行
Original assignee: 户津胜行
Priority date: 1998-02-24
Filing date: 1999-02-23
Publication date: 2004-09-30

Description

Combined structure of screwdriver head and screw

Technical Field

The present invention relates to a screwdriver bit and a screw for use therewith. And more particularly, to a combination structure between a screwdriver bit and a screw used in cooperation with the screwdriver bit, which enables a tight fit between a cross recess or a bit-matching recess formed at a head of the screw and the screwdriver bit for matching the recess, and enables quick and reliable tightening and loosening of the screw by transmitting a proper torque.

Background

A common screw and driver bit combination is generally known and is shown in fig. 13-16. That is, FIGS. 13 and 14 show a conventional screw with a cross-slot; a screwdriver for a cross-fluted screw is shown in fig. 15; and the state when the screw and the screwdriver bit are matched with each other is shown in fig. 16.

The prior art screw 10 shown in fig. 13 is provided with a cross-shaped recess 12 in its screw head 10 a. The cross groove 12 is provided with constant tapered groove portions 12a which extend from the end portion toward the center portion of one screw neck portion 10b, respectively. The cross 12 also has a gradually sloping generally conical bottom surface 14 at its bottom. Incidentally, reference numeral 13 denotes a wedge-shaped side wall portion formed between adjacent cross recesses 12. That is, the wedge-shaped side wall portion 13 is for snap-contacting a blade portion on a screwdriver bit as described later. Further, wedge-shaped attaching faces 17a or 17b are formed at adjoining corners of each inclined groove portion 12a, respectively, and extend from the position of the conical bottom face 14 to the opening edge portion of the cross recess 12 of the screw head 10 a. These wedge-shaped connecting surfaces 17a or 17b may be brought into biting contact with a portion of the blade portion of a driver bit described later.

On the other hand, the prior art screwdriver bit 20 shown in fig. 15 is provided with a blade 22 to fit the cross-shaped recess 12 of the screw 10. The driver bit 20 is further provided with extended blade portions 22a which are respectively extended to fit the shapes of the inclined groove portions 12a extended from the ends of the cross groove 12 toward the center portion of the screw neck portion 10 b. Incidentally, reference numeral 23 denotes a wedge-shaped side wall portion formed on both side surfaces of each of the above-described blades 22 or extended blades 22 a. That is, the wedge-shaped side wall portion 23 is adapted to be in biting contact with the wedge-shaped side wall portion 13 formed in the cross recess 12 of the above-mentioned screw 10.

According to the combined structure between the prior art screw and the driver bit shaped in the above-described manner, when the screw 10 and the driver bit 20 are mated with each other as shown in fig. 16, the blade portion 22 and the extended blade portion 22a of the driver bit 20 are respectively fitted in the inclined groove portion 12a of the cross groove 12, as described above. The side wall portions 23 of the blade portions 22 and the extended blade portions 22a contact the wedge-shaped side wall portions 13 in the cross recess 12 of the screw 10. Thus, rotating screwdriver bit 20 may transmit a predetermined torque to screw 10. That is, the screw can be tightened and loosened on the desired target object.

However, according to the combined structure between the prior art screw 10 and the screwdriver bit 20 shaped in the above-described manner, the cross-recess 12 in the screw head 10a constitutes a tapered groove portion 12a extending from the end of the screw neck 10b toward the central portion thereof. On the other hand, for the corresponding driver bit 20, the ridge of the extended blade portion 22a is fitted to the shape of the above-mentioned inclined groove portion 12a to fit the driver into the above-mentioned cross groove 12. Further, the ridge of the extended blade portion 22a widens rearward from the distal end portion thereof. In addition, the wedge-shaped side wall portion 23 formed on each blade portion 22 of the driver bit 20 will contact the wedge-shaped side wall portion 13 formed in the cross recess 12 of the screw 10. Thus, since the driver bit 20 and the cross recess 12 are in full wedge contact with each other, rotating the driver bit 20 in a predetermined direction causes the distal end of the driver bit 20 to jump outwardly (as shown by the arrow in fig. 16) along the inclined surface of the tapered slot portion 12a of the cross recess 12, resulting in a so-called "pull-out phenomenon".

Specifically, as shown in fig. 14, the shape of the cross recess in the prior art screw is formed in such a manner that the width of each cross recess 12 is relatively larger than the ridge portion of the extended edge portion 22a of the driver bit 20, so that the distal end of the driver bit 20 is engaged with the cross recess. On the other hand, the areas of the wedge-shaped side wall portion 13 and the wedge-shaped joint faces 17a, 17b formed at the boundary portions or corners between the adjacent cross recesses 12, 12 are relatively small. Thus, when the screwdriver bit 20 is rotated, a significant amount of stress is applied to the tapered side wall portion 13 and the tapered connecting surfaces 17a, 17 b. Therefore, as shown in fig. 14, with the hatched portion 15, a strong fastening resistance will result in gradual damage to the wedge-shaped side wall portion 13 and the wedge-shaped joint faces 17a, 17 b. Thus, the above-mentioned driver bit 20 is frequently removed as the damaged portion (the hatched portion 15) increases, so that the tightening operation cannot be performed.

From the above points, when the screwdriver bit 20 is rotated, a strong pushing force is required to be applied to the screwdriver bit 20 to abut the bit against the inclined groove portion 12a, so as to prevent the above-mentioned screwdriver bit 20 from coming off. However, such pressing of the cutter head will cause the target object, particularly fine parts, to be broken or damaged, although there is no problem when the target object is a rigid body such as metal.

Further, if the above-described drop-out phenomenon occurs, the wear of the distal end portion of the cutter head, i.e., the blade portion 22 and the extended blade portion 22a, is accelerated. Wear will cause more of the above run-out phenomenon, resulting in increased damage to the screw slot.

In addition, the above-mentioned coming-out phenomenon can be effectively prevented by applying a strong pushing force to the above-mentioned screwdriver bit 20. However, this results in the inability to deliver precise torque to the screw and different operators applying different thrusts to the screwdriver bit 20. As a result, the torque for tightening the screw may vary greatly from operator to operator.

Further, if the self-tapping screw is screwed into a target object made of synthetic resin or the like, a frictional force due to a thrust force is added in addition to a rotational frictional force of the screw. This results in a large amount of heat generation to such an extent that the hardness of the screwed portion of the target object can be lowered, thereby causing the screw to loosen or the target object to be damaged.

On the other hand, in manually tightening the screw, rotating screwdriver bit 20 while pressing screwdriver bit 20 against the screw requires a great deal of operator effort, resulting in operator fatigue.

In addition, according to the combined structure of the prior art screw 10 and the screwdriver bit 20, if the screw is tightened by a hand tool or a power tool, it is difficult to properly align the axis of the screw with the axis of the screwdriver bit while rotating the screw when fitting the distal end of the bit into the screw groove. Therefore, if the screw axis is inclined with respect to the screwdriver bit axis, not only the above-mentioned run-out phenomenon but also the screw slot damage frequently occurs.

In addition, when the screw is loosened, a coming-out phenomenon and a screw groove damage phenomenon occur, which are similar to the foregoing. However, in this case, the screw cannot be unscrewed, and the target object must be broken at a portion where the screw needs to be unscrewed. This condition occurs more frequently, in particular, when dust blocks the screw slot.

From the above points, the present applicant has proposed in the past that the screwdriver bit coming-out phenomenon and screw damage, which are generally occurring, can be effectively prevented by a screw and screwdriver bit combined structure (japanese patent laid-open publication nos. hei 8-145024 and hei 9-177743). In addition, this combination always enables a proper and quick tightening, and thus considerably improves the tightening efficiency even if the bit-matching groove on the screw has been damaged. This can be achieved by modifying the slot portions in the head-mating slot of the screw in the screw-to-driver head combination.

The screw and driver bit combination structure formed according to japanese patent laid-open publication No. hei 8-145024 is shown in fig. 12 (b). That is, a vertical end wall portion 32a having a predetermined depth is formed at the end of the bit-matching groove 32 of the screw head 30 a. The horizontal step portion 32b is formed from the vertical end wall portion. The tapered groove portions 32c are formed extending from these horizontal step portions 32b toward the central portion of the screw neck portion 30 b. Alternatively, it is also possible to have a wedge-shaped or curved groove portion extending from the above-mentioned vertical end wall portion toward the central portion of the screw neck 30 b. In addition, a generally conical bottom surface 34 is formed at the bottom of the trough portion. Thus, a screw is formed to fit the screwdriver bit, which includes a wing portion to be engaged in the vicinity of the above-mentioned stepped portion or curved groove portion (see fig. 12 (a)).

That is, referring to fig. 12(b), the right-angled edge portion 42a and the extended wing portion 42b formed on the wing portion 42 of the screwdriver bit 40 are fitted in the horizontal step portion 32b and the inclined groove portion 32c of the bit matching groove 32 of the screw 30, respectively. Thereafter, the side wall portion 43 and the extended wing portion 42b of the wing portion 42 will come into contact with the side wall portion 33 of the bit-matching groove 32 of the screw 30. Thus, a predetermined torque can be transmitted to the screw 30 by rotating the screwdriver bit 40.

The screw and driver bit combination structure formed according to japanese patent laid-open publication No. hei 9-177743 is shown in fig. 12 (c). That is, a vertical end wall portion 32a having a predetermined depth is formed at the end of the bit-matching groove 32 of the screw head 30 a. A non-planar bottom portion is formed by bulging from a lower edge portion of the vertical end wall portion toward a center portion of the screw. The tapered slot portion 32c extends from the ridge portion of the non-planar base toward the central portion of the screw neck. Further, a substantially conical bottom surface is formed at the bottom of the groove portion. This forms a screw to fit a screwdriver bit formed in the manner previously described (see fig. 12 (a)).

That is, referring to fig. 12(c), the horizontal surface portion 42a and the flange 42b formed on the flat blade portion 42 of the driver bit 40 are fitted in the non-planar bottom portion 32b and the inclined groove portion 32c in the bit matching groove 32 of the screw 30, respectively. Thereafter, the side wall portion 43 and the flange 42b of the wing portion 42 will come into contact with the side wall portion 33 of the bit-matching groove 32 of the screw 30. Thus, a predetermined torque can be transmitted to the screw 30 by rotating the screwdriver bit 40.

With the driver bit 40 according to the proposals above, the horizontal step portion 32b and the non-planar bottom portion 32b are formed in the bit-mating groove 32 of the screw 30. The contact area when the side wall portion 33 of the bit-matching groove 32 is in contact with the wing portion 42 of the driver bit 40 or the side wall portion 43 of the flat blade portion 42 can be increased. On the other hand, the wedge-shaped contact area when the tapered groove portion 32c of the bit matching groove 32 of the screw 30 is in contact with the wing portion 42 or the flat blade portion 42 of the driver bit 40 is only partial and small. Therefore, the phenomenon of coming-off in the prior art screw and screwdriver bit combined structure can be effectively prevented.

However, even the screw and screwdriver bit combination according to the above proposal still does not allow a satisfactory fluid and quick fit between the distal end portion of the screwdriver bit and the bit-matching groove formed in the head of the screw.

That is, in the structure of the screwdriver bit 40 proposed previously, it has been found that when the flat blade portion 42 with the horizontal surface portion 42a extending at substantially right angle is engaged with the vertical end wall portion 32a formed at the end of the above-mentioned bit matching groove 32 so as to be fitted into the bit matching groove 32 formed at the head of the screw 30, and the above-mentioned screwdriver bit is rotated, the distal end portion of the above-mentioned flat blade portion 42 is slidingly rubbed against the screw head surface, thereby damaging the surface.

Further, even if the distal end of the above-mentioned screwdriver bit 40 is fitted in the bit matching groove 32 of the screw head 30a, sometimes a pull-out phenomenon occurs. That is, as an example, in the combined structure of the driver bit shown in fig. 12(a) and the screw shown in fig. 12(b), sometimes the horizontal step portion 32b protruding from the vertical end wall portion 32a at a right angle at a predetermined depth in the bit matching groove 32 of the screw head portion 30a may not be appropriately formed at the time of mass production of the screw due to wear of the header punch for punching the bit matching groove 32, resulting in some rise of the right-angle intersection portion between the vertical end wall portion 32a and the horizontal step portion 32 b. In a case similar to this, it has been found that the distal end of the above-described screwdriver bit 40 may not be sufficiently fitted in the bit-matching groove 32 of the screw head 30a, resulting in unstable fitting and possibly causing a breakout phenomenon when the screwdriver bit 40 is rotated.

On the other hand, in the combined structure of the driver bit shown in fig. 12(a) and the screw shown in fig. 12(c), the bit matching groove 32 includes a non-planar bottom portion 32b instead of the above-described horizontal step portion 32b, so as to obtain a deeper dimension. This can avoid the above-mentioned drop-out phenomenon. However, since the strength of the screw neck 30b is reduced, it has been found that the screw head 30a may be cut off when the fastening operation is performed using the screwdriver bit 40.

Therefore, the present inventors have conducted intensive studies and experimental production. As a result, a screwdriver bit can be fitted to a screw having a vertical end wall portion of a predetermined depth, the wall portion being formed at the end of a bit-matching groove of a screw head, wherein a substantially planar bottom portion is formed extending from a lower edge portion of the vertical end wall portion toward a central portion of a screw neck, and a conical bottom surface is formed on the central portion, the present inventors formed the screwdriver bit in such a manner, i.e. the screwdriver bits mentioned above, comprise flat blades having substantially vertical ends, so that a distal end portion thereof fits in the bit-matching groove of the screw head along the vertical end wall portion, and a distal end face of said flat blades is shaped as a conical projection, which is inclined at an angle of 1 deg. to 45 deg. to the horizontal and preferably at an angle of 25 deg. to 35 deg. to the horizontal. By forming the screwdriver bit in this manner, while the above-mentioned flat blade portion slidingly rubs against the surface of the head of the screw when the distal end of the screwdriver bit is fitted into the bit-fitting groove and the screwdriver bit is rotated, it has been found that the surface is not damaged at all, and the distal end of the flat blade portion is fitted into the screw, whereby the occurrence of the coming-out phenomenon when the screwdriver bit is rotated can be effectively prevented.

On the other hand, a screw to be fitted with the above-described screwdriver bit is a screw comprising: the bit of the screw head matches the end of the groove, they are shaped into the vertical end wall part with predetermined depth; step portions formed at lower edge portions of the vertical end wall portions; chute portions formed to be inclined toward a central portion of one neck portion; a conical bottom surface formed in the center of the screw, wherein the tip-fitting groove widens radially outward from the central portion of the head of the screw, and the opening angle between the side wall portions facing each other in the adjacent grooves is an acute angle slightly smaller than a right angle. When the blade portion of the driver bit comes into contact with the respective side wall portion shaped to widen outwardly in the bit-mating groove of the screw, it has been found that the clearance between the blade portion and the groove can be made as small as possible, thereby allowing the screw and the driver bit to be properly mated together and enabling the escape phenomenon to be reliably prevented.

Further, the screw to be fitted with the above-mentioned screwdriver bit is a screw comprising: step portions provided on an end of the bit fitting groove of one screw head; tapered groove portions formed extending from the stepped portions toward a central portion of a screw neck portion; a generally conical bottom surface formed at the bottom of the screw; and wall portions formed at ends of the bit fitting grooves and recessed inward from a vertical direction by a predetermined depth, and recessed in a substantially "<" -shaped cross section. It has been found that in the screw, a portion recessed from the vertical surface can always serve as a gap portion, and therefore, dust particles and foreign matter can be pushed into the above gap portion to be removed. It has also been found that the degree of freedom of the distal end of the screwdriver bit is increased when mating the screwdriver bit with a screw, so that the distal end of the blade always fits properly with the screw, thereby facilitating smooth tightening and loosening of the screw.

Therefore, it is an object of the present invention to provide a combined structure of a driver bit and a screw, which can prevent damage caused by sliding friction against a head surface of the screw, and can reliably prevent a coming-out phenomenon when the driver bit is fitted to the screw, so that the screw can always be properly and rapidly tightened, thereby remarkably improving working efficiency.

Summary of The Invention

In order to achieve the above object, a screwdriver bit according to the present invention is a screwdriver bit for a screw comprising a vertical end wall portion having a predetermined depth, said wall portion being formed at an end of a bit-matching groove of a screw head, wherein a substantially flat bottom portion is formed extending from a lower edge portion of the vertical end wall portion toward a central portion of a screw neck, and a conical bottom surface is formed at the central portion, said screwdriver bit being characterized by comprising flat blades having substantially vertical ends to fit a distal end portion thereof in the bit-matching groove of the screw head along the vertical end wall portion, wherein a distal end face of said flat blades is shaped as a conical projecting portion inclined at an angle of 1 ° to 45 ° with respect to a horizontal direction.

In this case, the above-mentioned conically-shaped convex portion on the distal end face of the flat blade portion may be formed to be inclined at an angle of 25 ° to 35 ° with respect to the horizontal direction.

Further, the above-mentioned conically-shaped protrusion on the distal end face of the flat blade may be shaped such that its conically-shaped surface is formed as a single conical surface or a multi-step conical surface.

In addition, the conical surface of the above-described conical projecting portion on the distal end face of the flat blade portion may be shaped to be convex or concave in cross section.

On the other hand, the two side walls at the distal end of the flat blade may be shaped to widen outwardly to mate with a bit-mating groove on the screw shaped to widen radially outwardly from the center portion of the screw head.

In addition, at least one of the flat blades may be provided with a notch extending axially along the cutter head from the distal surface of the blade and having a predetermined length.

In another aspect, a screw cooperable with a screwdriver bit according to the present invention is characterized in that it comprises: the screw head includes stepped portions provided on ends of a bit mating groove of a screw head, tapered groove portions formed extending from the stepped portions toward a central portion of a screw neck, a substantially conical bottom surface formed on a screw bottom, and wall portions formed on ends of the bit mating groove and recessed inward from a vertical direction by a predetermined depth.

In this case, the wall portion formed at the end of the insert mating groove may be recessed with a substantially "<" -shaped cross section.

Further, the bit-matching groove may be shaped to widen radially outward from the central portion of the screw head, and the opening angle between the side wall portions facing each other of the above-mentioned adjacent grooves may be an acute angle slightly smaller than a right angle.

In addition, as a screw which can be fitted with the screwdriver bit according to the present invention, a cross/line screw characterized in that one screw head is provided with a bit-matching groove composed of crossed grooves; one straight groove in the cross cutter head matching groove is shaped in such a way that the blade part of a cross screwdriver head can be matched in the straight groove; the other straight groove is shaped so that the blade part of the straight screwdriver head can be matched in the straight screwdriver head; substantially vertical end wall portions having a certain depth are formed at the end of the one of the straight grooves, and wall portions are formed on the vertical end wall portions at a predetermined depth with a substantially "<" -shaped cross section and are recessed from the vertical direction.

Furthermore, the present invention is characterized by combining a screwdriver bit formed in the above-described manner with a screw comprising: the bit of the screw head matches the end of the groove, they are shaped into the vertical end wall part with predetermined depth; step portions formed at lower edge portions of the vertical end wall portions; chute portions formed to be inclined toward a central portion of one neck portion; a conical bottom surface formed in the center of the screw. The screw is shaped such that the bit-mating groove widens radially outward from a central portion of the screw head; and the opening angle between the side wall portions facing each other of the adjacent grooves is an acute angle slightly smaller than a right angle.

In addition, the present invention is characterized by combining a screwdriver bit with a screw comprising: horizontal bottom or beveled slot portions formed on the screw head extending from the lower edge portion of the bit mating slot end toward the central portion of a screw neck; a conical bottom surface formed on the screw center portion; and wall portions formed at ends of the bit fitting grooves and recessed inward from the vertical direction by a predetermined depth.

In addition, the present invention is characterized in that the screwdriver bit is combined with a cross/straight screw in which one screw head is provided with a bit-matching groove composed of crossing grooves; one straight groove in the tool bit matching groove is shaped in such a way that the blade part of a cross screwdriver bit can be matched in the straight groove; the other straight groove is shaped so that the blade part of the straight screwdriver head can be matched in the straight screwdriver head; and a substantially vertical end wall portion having a certain depth is formed at an end of the one straight groove.

In this case, the cross/straight screw may be shaped such that one of the straight grooves of the bit mating groove is shaped to widen significantly outward; in the other straight groove, the groove is shaped to widen significantly outward; and the blade portion of one screwdriver bit will contact the side wall portions formed by the above-mentioned outwardly widened grooves simultaneously and with equal clearance.

Brief description of the drawings

FIG. 1 is an enlarged side elevational view of the main portion of one embodiment of a screwdriver bit according to the present invention;

FIG. 2 is an enlarged side perspective view of a major portion of the screwdriver bit shown in FIG. 1;

FIG. 3 is an enlarged bottom view of the screwdriver bit shown in FIG. 1;

FIGS. 4(a) - (d) are schematic side views of various modifications of the distal end portion of the screwdriver bit according to the present invention;

FIG. 5 shows another modified structure of the screwdriver bit according to the present invention; (a) is an enlarged side view of its body; (b) is an enlarged bottom view thereof;

FIG. 6 shows an example of a configuration of a screw suitable for use with a screwdriver bit according to the present invention; (a) is an enlarged cross-sectional side view of the screw head body; (b) is an enlarged top view of the screw head;

FIG. 7 is an enlarged cross-sectional side view of the body of a screwdriver bit according to the present invention as it is mated with the screw of FIG. 6;

FIG. 8 shows another example of a configuration of a screw preferably used in cooperation with a screwdriver bit according to the present invention; (a) is an enlarged top view of the screw head; (b) is an enlarged cross-sectional top view of the head body of the screw cooperating with the screwdriver bit;

FIG. 9 shows another example of a configuration of a screw preferably used in conjunction with a screwdriver bit according to the present invention; (a) is an enlarged cross-sectional side view of the screw head body; (b) is an enlarged top view of the screw head; (c) is an enlarged cross-sectional side view of the screw head body that mates with the screwdriver bit;

FIG. 10 shows an example of a cross/straight groove screw configuration that may be used with a screwdriver bit according to the present invention; (a) is an enlarged top view of the head of the cross/line screw to show one example of the structure; (b) is an enlarged top view of the cross/line screw head to show a modified configuration;

FIG. 11 shows a modified form of the screw of FIG. 10; (a) is an enlarged top view of the screw head; (b) is an enlarged cross-sectional side view of the screw head body;

FIG. 12 shows an example of a conventionally proposed screw structure and a driver bit therefor; (a) is an enlarged side view of the screwdriver bit body; (b) is an enlarged cross-sectional side view of the body of one conventionally proposed example of a screw construction and its cooperating driver bit; (c) is an enlarged cross-sectional side view of the body of another conventionally proposed screw structure example and its cooperating driver bit;

FIG. 13 is a cross-sectional side view of the body of a conventional Phillips screw;

FIG. 14 is a top view of the screw head of the cross-slot screw of FIG. 13;

FIG. 15 is a side view of a screwdriver bit body for use with a conventional Phillips screw; and

FIG. 16 is a cross-sectional side view of the cross-slot screw body of FIG. 13 and the screwdriver bit of FIG. 15 mated with each other.

Best mode for carrying out the invention

Embodiments of the screwdriver bit and screw combination according to the present invention will now be explained in detail by referring to the drawings.Example 1(example of Structure of Screwdriver bit 1)

Fig. 1 to 3 show an embodiment of a screwdriver bit according to the invention. Referring to fig. 1-3, reference numeral 50 designates a screwdriver bit according to the present invention. The distal end of the blade portion of the screwdriver bit 50 is adapted to fit in the bit-matching groove 32 formed in the form of a cross-shaped groove in the central portion of the screw head 30a of the conventionally proposed screw 30 as shown in fig. 6 and 7.

Thus, the driver bit 50 in the present embodiment includes a flat blade portion 52 to match the bit matching groove 32 of the screw 30 and to engage with the vertical end wall portion 32a and the flat bottom portion 32b formed at the end of the bit matching groove 32. The screwdriver bit 50 also includes a distal surface or a conical projection 54 formed by the flat blade portion 52 at an angle theta of 1 deg. to 45 deg., preferably 25 deg. to 35 deg., relative to the horizontal plane, corresponding to the inclination of the angled slot portion 32c from the flat bottom 32b of the bit mating slot 32 toward the central portion of the screw neck 30 b.

Incidentally, reference numeral 53 denotes side wall portions formed on both side faces of the above-mentioned flat blade portion 52, which are substantially vertical and allowed to be slightly wedge-shaped. Thus, the side wall portion 53 can be in snap contact with the side wall portion 33 formed in the bit mating groove 32 of the screw 30. Thus, these driving surfaces can provide a sufficiently wide engagement area to effectively prevent back-out caused by conventional screw and driver bit combinations.

Fig. 4(a) - (d) show various modified structures of the conical projecting portion 54 formed on the distal end face of the flat blade portion 52 of the driver bit 50 according to the present invention, respectively. That is, the conical surface of the above-described convex portion 54 shown in fig. 4(a) is shaped into a single conical surface 54 a. In addition, the conical surface of the above-described convex portion 54 shown in fig. 4(b) is shaped into a multi-step (two-step) tapered surface 54b inclined at different angles, respectively. Further, the conical surface of the above-described convex portion 54 shown in fig. 4(c) is shaped in cross section as a convex surface 54 c. Finally, the conical surface of the above-described convex portion 54 shown in fig. 4(d) is shaped in cross section as a concave surface 54 d.Example 2(example of Structure of Screwdriver bit 2)

Fig. 5(a) and (b) show another embodiment of the flat blade part 52 of the driver bit 50 according to the present invention. That is, in the present embodiment, as shown in fig. 5(a) and (b), at least one of the flat blades 52 is formed with a notch 55 having a predetermined length and extending from the blade distal end surface along the bit axis.

Providing such a notch 55 on the flat blade 52 will result in a resilient radial displacement of one blade section 52a from the axial center portion of the driver bit 50. The various actions of the blade section 52a facilitate maintaining engagement between the screwdriver bit and the bit-mating slot 32 of the screw 30, as described below.Example 3(structural example 1 of screw)

Fig. 6(a) and (b) show an example of a configuration of a screw 30 suitable for use with a screwdriver bit 50 according to the present invention. That is, in fig. 6(a) and (b), the screw 30 is provided with a bit-matching groove 32 on the head 30 a. Incidentally, the bit matching grooves 32 intersect at right angles in a cross (+) shape at the center portion of the screw head 30 a. On the other hand, the bit mating groove 32 is formed at its end with a vertical end wall portion 32a having a predetermined depth. Further, a flat bottom portion 32b is formed extending from a lower edge portion 32 a' of the end wall portion 32a toward a central portion of the screw neck portion 30 b. In addition, the inclined groove portion 32c is formed extending from the flat bottom portion 32b toward the central portion of the screw neck portion 30 b. Finally, a slightly inclined, generally conical bottom surface 34 is formed in the central portion.

Incidentally, reference numeral 33 denotes substantially vertical side wall portions which are respectively formed between the adjacent bit mating grooves 32 with draft (angle for drawing the header punch out therefrom) of about 1.5 ° to 2 °. In this way, the side wall portion 33 will snap into contact with the side wall portion 53 on the flat blade portion 52 of the above-described screwdriver bit 50 according to the present invention.

Further, similarly to the prior art screw with cross recesses shown in fig. 14, wedge-shaped connecting faces 37a, 37b are formed at adjacent corners of the above-mentioned bit-matching recess 32, extending from the position of the conical bottom face 34 to the opening edge portion of the bit-matching recess 32 of the screw head 30 a.

The screw 30 thus formed has a flat bottom portion 32b at the end of the bit-fitting groove 32 of the screw head 30a, and a tapered groove portion 32c formed extending from the flat bottom portion 32b toward the central portion of the screw neck portion 30 b. The overall area of the wedge-shaped contact portion of the bit-mating groove 32 is reduced to provide local contact with the screwdriver bit. Further, this can increase the area of the side wall portion 33 which contacts the distal end of the driver bit at the boundary portion between the adjacent bit mating grooves 32, 32 (the surface area of the screw to which torque is applied by the driver bit, i.e., the driven surface area).

Fig. 7 shows a situation of a screwdriver bit 50 according to the invention when mated with the screw 30 shown in fig. 6(a) and (b). That is, in the present embodiment, as shown in fig. 7, it is assumed that the flat blade portion 52 formed at the distal end of the driver bit 50 is in contact with the bit matching groove 32 formed in the screw head 30a of the screw 30. Since the distal end face of the flat blade portion 52 is formed as the conically-bulging portion 54, it is possible to prevent the blade portion from being deformedThe flat blade 52 will contact the open edge portion of the bit-mating groove 32 in a very small area consisting of dots or lines, thereby enabling the center portions of the two to be quickly and easily aligned with each other. This may reduce wear and damage to the head of the screw to allow the screwdriver bit 50 to fit directly and precisely with the screw 30.Example 4(structural example 2 of screw)

Fig. 8(a) and (b) show another example of the structure of a screw 30 preferably used in cooperation with a screwdriver bit 50 according to the present invention. That is, in the present embodiment, as shown in fig. 8(a) and (b), the grooves 33a, 33b in the bit-matching groove 32 of the screw 30 are formed to widen radially outward from the screw head 30a against each other. On the other hand, the side wall portion 53 at the distal end of the flat blade portion 52 of the driver bit 50 for matching with the grooves 33a, 33b is also widened outward to correspond to the screw thus formed. That is, the side wall portion 53 is shaped such that the side wall portions 53a, 53b widen outward.

Assuming that the flat blade portion 52 of the driver bit 50 contacts the respective side wall portions (T1, T2, T3, and T4) in the bit mating groove 32 of the screw 30, the grooves 33a, 33b of the bit mating groove 32 are widened outward. In this case, forming the side wall portions 53a, 53b widened outwardly at the distal end of the flat blade portion 52 of the driver bit 50 makes it possible to make the gap between the above-mentioned grooves 33a, 33b and the above-mentioned side wall portions 53a, 53b as small as possible to suitably match the screw with the driver bit. In addition, the opening angle β between the adjacent side wall portions facing each other in each groove 33a, 33b can be set to an acute angle slightly smaller than a right angle, thereby ensuring prevention of the driver bit 50 from coming out when tightening the screw and thus transmitting a uniform torque to the screw 30.Example 5(structural example 3 of screw)

Fig. 9(a), (b) and (c) show another example of the structure of a screw 30 preferably used in cooperation with a screwdriver bit 50 according to the present invention. That is, in the present embodiment, as shown in fig. 9(a) and (b), a wall portion 32aa is formed at the end of the bit matching groove 32 of the screw 30 with a substantially "<" -shaped cross section, and the wall portion 32aa is recessed inward from the vertical surface by a predetermined depth. Next, the step portion 32b 'protrudes in a substantially horizontal direction from the lower edge portion 32 a' of the recessed wall portion 32 aa. In addition, each inclined groove portion 32c is formed extending from the step portion 32 b' toward the central portion of the screw neck portion 30 b. In addition, a slightly inclined, generally conical bottom surface 34 is formed at the bottom. The other shape is the same as that of the screw 30 in embodiment 3 shown in fig. 6(a) and (b).

According to the screw 30 in the present embodiment, the recessed wall portion 32aa and the step portion 32 b' are provided on the end portions of the bit fitting groove 32 of the screw head 30a, respectively. Further, each inclined groove portion 32c is formed extending from the end of the above-described stepped portion 32 b' toward the central portion of the screw neck portion 30 b. The overall area of the wedge-shaped contact portion of the bit-mating groove 32 is reduced to provide local contact with the screwdriver bit. Further, this can increase the area of the side wall portion 33 in contact with the screwdriver bit distal end at the boundary portion between the adjacent bit mating grooves 32, 32.

That is, according to the present embodiment, as shown in fig. 9(c), the distal end of the flat blade 52 of the driver bit 50 is fitted in each stepped portion 32 b' of the bit matching groove 32 of the screw 30, then, the side wall portion 53 of the blade distal end is brought into contact with the side wall portion 33 of the bit matching groove 32 of the screw 30, and thereafter, the driver bit 50 is rotated, thereby transmitting a predetermined torque to the screw 30. In particular, according to the combined structure of the screw 30 and the driver bit 50 in the present embodiment, when the recessed wall portion 32aa is formed at the bit matching groove 32 end portion of the screw 30 that matches the driver bit 50, a portion recessed from the vertical surface can always be used as one gap portion G. In this way, the dust particles and foreign substances in the blade fitting groove 32 can be pushed into the above-mentioned gap portion G by the screw head 50 being strongly fitted therein, thereby removing them. This facilitates the secure mating of the distal end of the flat blade portion of the screwdriver bit 50 with the bit mating groove 32 of the screw 30.

Further, according to the combined structure of the screw 30 and the driver bit 50 in the present embodiment, if the opening portion side of the bit mating groove 32 is damaged when screwing or unscrewing the screw using the general cross screwdriver bit, the above-described driver bit 50 can push chips accumulated in the insert mating groove 32 into the gap portion G, thereby removing them. At the same time, the above-mentioned screwdriver bit 50 can be made to fit together suitably between the bottom side of the bit-matching groove 32 and the distal end of the flat blade portion of the screwdriver bit 50 to accomplish the screwing or unscrewing operation.

In addition, according to the combined structure of the screw 30 and the driver bit 50 of the present invention, when attempting to insert the driver bit 50 into the bit matching groove 32, even if the driver bit 50 is slightly inclined with respect to the axial direction of the screw 30, it is possible to easily and firmly fit the driver bit 50 into the bit matching groove 32. This is because the presence of the above-described recessed wall portion 32aa improves the degree of freedom of the distal end of the driver bit 50.Example 6(structural example 4 of screw)

Fig. 10(a) and (b) show an example of a configuration of a screw 30 suitable for use with a screwdriver bit 50 according to the present invention.

That is, one cross/straight screw 30A shown in fig. 10(a) is provided with a pair of straight grooves 31a, 31b crossing each other at the center portion of the screw head 30A. According to the cross/straight screw 30A in the present embodiment, one of the above-described straight grooves 31a is used to form a vertical end wall portion 35a having a predetermined depth at the end. Further, the joint portion 32 b' is formed extending in a substantially horizontal direction from the lower edge portion of the vertical end wall portion 35 a. Next, each inclined groove portion 32c 'is formed extending from the step portion 32 b' toward the central portion of the screw neck. In addition, a slightly inclined, generally conical bottom surface 34 is formed at the bottom. The other straight groove 31b is formed to extend horizontally and has a width and a depth sufficient to be engaged with the blade portion of the phillips head. Thus, the screwdriver bit 50 according to the present invention may also be used with the cross/straight screw 30A so formed.

Fig. 10(b) shows a modified structure of the cross/straight screw 30A. That is, in this case, one straight groove 31a and the other in the cross/straight screw 30AIn the straight groove 31b, grooves 33a ', 33 b' are formed to be widened outward so as to correspond to the blade portions 52 of the driver bit 50. Since the screw has such a shape, the cross/straight screw 30A can provide the same function and effect as the screw 30 in the above-described embodiment 4 shown in fig. 8(a) and (b) when the blade portion 52 of the driver bit 50 is fitted with the bit-matching groove of the cross/straight screw 30A.Example 7(structural example 5 of screw)

Fig. 11(a) and (b) show another modified structure of the cross/straight screw 30A shown in fig. 10(a) and (b). That is, in the present embodiment, as shown in fig. 11(a) and (b), a wall portion 32aa is formed at the end of the bit fitting groove 32 with a substantially "<" -shaped cross section with respect to one straight groove 31a of the cross/straight screw 30A. Here, the wall portion 32aa is recessed inward from the vertical surface by a predetermined depth. Thus, the same head matching groove 32 as the screw 30 in the above embodiment 5 shown in fig. 9(a) is formed.

Thus, the cross/straight screw 30A thus formed can provide the same function and effect as those of the screw 30 in embodiment 5 described above.

The foregoing description of the preferred embodiments of the invention has been presented. However, the present invention is not limited to the above embodiments. For example, in the above-described respective structural examples of the screw, the present invention can also be implemented into a pan head screw or a flat head screw. Further, the respective configuration examples can be effectively used in combination. It is therefore evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention.

As can be seen from the above embodiments, the screwdriver bit according to the present invention can be fitted to a screw comprising a vertical end wall portion having a predetermined depth, the wall portion being formed at the end of a bit-matching groove of a screw head, wherein a substantially flat bottom portion is formed extending from a lower edge portion of the vertical end wall portion toward a central portion of a screw neck, and a conical bottom surface is formed on the central portion. The screwdriver bit comprises flat blades having substantially vertical ends for fitting a distal end portion thereof along vertical end wall portions in bit-matching grooves of the screw head, characterized in that a distal end face of said flat blades is shaped as a conical projection inclined at an angle of 1 ° to 45 ° with respect to the horizontal. While the flat blade portion described above slidingly rubs against the surface of the head of the screw when the distal end of the screwdriver bit is mated with the bit-mating groove, the surface is not damaged at all. In addition, the far end of the flat blade part is matched in the screw, so that the phenomenon of falling-off when the screwdriver head rotates can be effectively prevented.

Further, according to a screwdriver bit and screw combination according to the present invention, a flat blade formed at a distal end of the screwdriver bit will be in contact with a bit-matching groove formed at a head of the screw. Since the distal end of the flat blade is shaped as a conical projection, the flat blade will contact the open edge portion of the tool bit mating groove in a very small area consisting of a point or line, thereby enabling the central portions of the two to be quickly and easily aligned with each other. This makes it possible to reduce wear and damage to the head of the screw so that the screwdriver bit fits directly and precisely with the screw.

Further, at the distal end of the flat blade portion of the driver bit, the side wall portion is formed to widen outwardly, and the respective side wall portions in the bit-matching groove of the screw are also formed to widen outwardly. This makes it possible to keep the clearance between the screwdriver bit and the screw as small as possible. In addition, the opening angle β between the adjacent side wall portions facing each other on each groove may be set to an acute angle slightly smaller than a right angle. Therefore, it is possible to effectively prevent the driver bit from coming out when the screw is tightened and thus to transmit a uniform torque to the screw.

Claims

1. A driver bit for a screw, which is adapted to a screw, and which has a head portion formed at an end portion thereof with a vertical end wall portion having a predetermined depth and a bit-matching groove having a bottom portion substantially flat from a lower edge portion of the vertical end wall portion toward a central portion of a screw neck portion while forming the notch in a shape gradually widening radially outward from the central portion of the head portion and forming a conical bottom surface on the central portion,

the screwdriver bit is provided with: a blade having a substantially vertical end flat portion, arranged so that the flat portion fits in the bit matching groove of the screw head along a vertical end wall portion of the screw head, and formed in a shape in which both side walls of a distal end thereof gradually widen outward in a radial direction to fit in the notch of the bit matching groove; and a conical projection on the distal face of the flat blade inclined at an angle of 25 ° to 35 ° with respect to the horizontal.

2. The screwdriver bit as claimed in claim 1, wherein the conical projection on the distal face of the flat blade is shaped such that its conical surface is formed as a single conical surface.

3. The screwdriver bit as claimed in claim 1, wherein the conical surface of the conical projection on the distal face of the flat blade is shaped to be convex in cross section.

4. A screw, comprising:

step portions provided on ends of the bit fitting grooves of the screw head, respectively;

tapered groove portions formed extending from the stepped portions toward a central portion of the screw neck portion, respectively;

a generally conical bottom surface formed at the bottom of the screw; and

wall portions formed at ends of the bit fitting grooves and recessed inward from the vertical direction by a predetermined depth to have a cross-sectional shape of substantially "<".

5. The screw of claim 4, wherein the bit-mating grooves are shaped to widen radially outwardly from a central portion of the head of the screw, and wherein the opening angle between the facing side wall portions of the adjacent grooves is an acute angle slightly less than a right angle.

6. A cross/straight screw is characterized in that,

one screw head has a bit-mating groove formed by intersecting grooves,

one of the straight grooves in the mating grooves of the cross cutter head is shaped so that the blade portion of a cross screwdriver head fits therein,

the other straight groove is shaped so that the blade part of the straight screwdriver head can be matched in the straight screwdriver head,

a substantially vertical end wall portion having a certain depth is formed at an end of the one straight groove, and

wall portions are formed on the vertical end wall portions at a predetermined depth with a substantially "<" -shaped cross section and are recessed from the vertical direction.

7. A combined structure of a screwdriver head and a screw is characterized by comprising,

the screw includes:

the cutting head of the screw head matches the ends of the grooves, which are shaped as vertical end wall portions having a predetermined depth,

step portions formed at lower edge portions of the vertical end wall portions,

chute portions formed to be inclined toward a central portion of one neck portion,

a conical bottom surface formed at the center of the screw,

the head-mating groove widens radially outwardly from the central portion of the head of the screw, and the opening angle between the side wall portions facing each other in the above-mentioned adjacent grooves is an acute angle slightly smaller than a right angle; and

a screwdriver bit formed with:

a blade portion having a substantially vertical end flat portion, which is disposed so that the blade portion fits in the bit mating groove of the screw head along a vertical end wall portion of the screw head, and is formed in a shape in which both side walls of a distal end thereof gradually widen outward in a radial direction so as to fit in the notch of the bit mating groove, and

a conically shaped projection on the distal face of the flat blade that is inclined at an angle of 25 ° to 35 ° with respect to horizontal.

8. A combined structure of a screwdriver head and a screw is characterized by comprising,

a screw, comprising:

horizontal bottom portions or tapered groove portions formed on the screw head portion extending from a lower edge portion of the tip matching groove end portion toward a central portion of a screw neck portion,

a conical bottom surface formed on the screw center portion, an

Wall portions formed at ends of the bit fitting grooves and recessed inward from a vertical direction by a predetermined depth; and

a screwdriver bit formed with:

a conical projection on the distal face of the flat blade inclined at an angle of 25 ° to 35 ° with respect to horizontal; and is

The driver bit matching groove and the flat blade of the driver bit are formed as a groove and a blade, respectively, having ends gradually widened and are simultaneously contacted with each other with an equal gap.

9. A combined structure of a screwdriver head and a cross/straight screw is characterized by comprising,

a screw having:

the head of the screw is provided with a cutter head matching groove formed by crossed grooves,

one straight groove in the cutter head matching groove is shaped in such a way that the blade part of a cross screwdriver cutter head can be matched in the straight groove,

the other straight groove is shaped so as to enable the blade portion of a straight screwdriver bit to fit therein, an

A substantially vertical end wall portion having a certain depth is formed at an end of the one straight groove;

a screwdriver bit formed with:

The head of the screw is formed with a straight groove in the groove and the flat blade of the driver head are formed with a groove and a blade having ends gradually widened, respectively, and are simultaneously contacted with each other with an equal gap.

10. The screwdriver bit as claimed in claim 1, wherein the conically shaped protrusion on the distal surface of the flat blade is shaped such that its conically shaped surface is formed as a multi-step conical surface.

11. The screwdriver bit as defined in claim 1, wherein the conical surface of the conical projection on the distal face of the flat blade is shaped to be concave in cross section.