WO2013031339A1

WO2013031339A1 - Driver bit

Info

Publication number: WO2013031339A1
Application number: PCT/JP2012/065578
Authority: WO
Inventors: 康明田口; 二郎田口
Original assignee: 株式会社ベッセル工業
Priority date: 2011-08-30
Filing date: 2012-06-19
Publication date: 2013-03-07
Also published as: JP5616860B2; JP2013049100A

Abstract

Provided is a driver bit having excellent durability. A driver bit (10) is provided with: a pair of point portions (12) disposed at the ends; a body portion (14) to be fitted in a socket portion of a rotating tool to receive rotating force from the rotating tool; and a pair of locking groove portions (16) disposed at the ends of the body portion (14) into which a locking member at the socket portion of the rotating tool is to be fitted. The point portions (12) include an inclined surface such that the cross sectional area of a blade in a plane perpendicular to the axial central line of the bit becomes smaller toward a front end. The inclined surface includes a first inclined surface (12A) closer to a front end of the bit and a second inclined surface (12B) continuous with the first inclined surface (12A) and closer to a rear end of the blade. The second inclined surface (12B) has a greater cross sectional area of the blade than the first inclined surface (12A) in a plane perpendicular to the bit axial central line.

Description

Driver bit

TECHNICAL FIELD The present invention relates to a driver bit that is detachably attached to a rotary tool such as an electric tool and an air tool, and is used for tightening or loosening a screw by transmitting rotational torque, and in particular, a driver having excellent durability. It is about bits.

In general, a driver bit for rotating a screw having a cross groove formed on a screw head includes a so-called Philips type. The tip of the driver bit is provided with a cross-shaped blade (plus blade) in plan view, and the blade is formed so as to gradually become thicker from the tip to the rear end.
In such a driver bit, a plus-type blade formed at the tip of the bit is inserted into a bit insertion groove such as a screw formed according to a standard (for example, JIS standards No. 1, No. 2, No. 3, etc.). Since it is designed to match, there is a disadvantage that only one screw or the like having a matching bit insertion groove can be rotated well with a single screwdriver.

Japanese Patent Laid-Open No. 2001-9744 (Patent Document 1) discloses a bit structure of a plus driver that solves such a problem. In this bit structure, the tip shape is set to a shape in which three steps are formed on each of the four blades, and the dimensions (blade height and blade width) of each blade are generally frequently used. The size is set to match the bit insertion portion such as three types of screws. The first blade is the JIS standard size 1 (blade height and blade width), the second blade is the JIS standard size 2 (blade height and blade width), third The blades are set to dimensions of the so-called No. 3 in the JIS standard (blade height and blade width). As described above, since the first blade, the second blade, and the third blade having different sizes are provided, the four blades have various sizes only by changing the insertion depth into the bit insertion groove such as a screw. It is possible to reliably match the bit insertion groove of the bit. Therefore, with a single screwdriver, a screw with a different count can be rotated well without crushing the bit insertion groove.

Japanese Patent Laid-Open No. 2001-9744

However, the driver bit disclosed in the above-mentioned publication has the following problems. That is, the outer edge trajectory when the four blades of this driver bit are viewed from the side is not an inclined straight line, but three inclined straight lines that match the dimensions of the popular names 1 to 3 in the JIS standard, It is set as an outer edge locus in which three straight lines orthogonal to the bit axis line are alternately arranged. For this reason, stress concentration occurs at the intersection of the inclined straight line and the straight line, and the durability may be lower than that of a normal driver bit.

When rotating a screw having a size of No. 3 with this screwdriver bit, only the third blade contacts the left and right wall surfaces of the bit insertion groove, and the first blade and the second blade touch the wall surface. Do not touch (see FIG. 2A and FIG. 2B). For this reason, it is assumed that the screw does not rotate because sufficient torque cannot be applied to the screw. As described above, it is assumed that it is difficult to rotate a screw having a different count with a single screwdriver (even if it is possible to avoid crushing the bit insertion groove). Further, it may be assumed that such a shape of the bit tip does not conform to the JIS standard. For this reason, the inventor of the present application has not been focused on the viewpoint of rotating a screw having a different number with a single screwdriver, but has eagerly developed it with the aim of improving durability.

The present invention has been developed with the aim of improving durability as described above, and an object thereof is to provide a driver bit with excellent durability.

In order to achieve the above-described object, the present invention takes the following technical means.
That is, the driver bit according to the present invention has a cross-shaped blade in plan view that fits into a cross groove formed in the screw head. This blade is provided with an inclined surface that tapers as the cross-sectional area of the blade in a plane perpendicular to the bit axis extends toward the tip. This inclined surface is composed of at least two inclined surfaces.

According to this configuration, for example, the inclined surface on the rear end side of the blade is larger than the inclined surface on the front end side of the blade fitted in the cross groove formed on the screw head so that the sectional area of the blade in the vertical plane is larger. If comprised, the cross-sectional area of a blade can be made larger than before. For this reason, the durability of the driver bit can be improved by improving the strength of the blade of the driver bit.
Here, the inclined surface can be configured to include a first inclined surface on the bit front end side and a second inclined surface on the rear end side of the blade that is continuous with the first inclined surface. In this case, the second inclined surface can be configured such that the cross-sectional area of the blade in the vertical surface is larger than that of the first inclined surface.

According to this configuration, when the inclined surface on the rear end side of the blade is configured so that the cross-sectional area of the blade in the vertical plane is larger than the inclined surface on the front end side of the blade fitted in the cross groove formed on the screw head. The cross-sectional area of the blade can be made larger than before. Further, since the inclined surfaces are continuous, the occurrence of stress concentration can be avoided. For this reason, the durability of the driver bit can be improved by improving the strength of the blade of the driver bit.

Further, the first inclined surface can be configured to be the inclined surface of the portion that fits into the cross groove, and the second inclined surface can be configured to be the inclined surface of the portion that does not fit into the cross groove. .
According to this configuration, the part that fits into the cross groove formed on the screw head expresses the basic function of the driver bit, which is a function that fits into the cross groove and sufficiently transmits the rotational torque to the screw. The durability of the driver bit can be improved. In addition, by comprising in this way, about the part fitted to the cross groove formed in the screw head, it conforms to a JIS standard.

Further, the blade is configured such that, in plan view, an acute angle θ at which the extended line representing the first inclined surface intersects the line representing the second inclined surface satisfies 0 <θ ≦ 46 °. can do.
According to this configuration, since the second inclined surface does not spread extremely, the driver bit can be manufactured by a normal manufacturing method.

According to the present invention, it is possible to provide a driver bit with excellent durability.

It is a perspective view of a driver bit concerning a 1st embodiment of the present invention. It is a side view of the driver bit of FIG. It is a front view of the driver bit of FIG. FIG. 3 is a side view of the driver bit rotated by 45 ° in the bit axis direction from the state of FIGS. 2A and 2B. FIG. 3 is a front view of a driver bit rotated by 45 ° in the bit axis direction from the state of FIGS. 2A and 2B. It is a perspective view of the driver bit of a comparative product. It is a side surface enlarged view of the front-end | tip part of the driver bit of FIG. 2A and FIG. 2B. It is a front enlarged view of the front-end | tip part of the driver bit of FIG. 2A and 2B. FIG. 5 is an enlarged side view of a tip portion of the driver bit of FIG. 4. It is a front enlarged view of the front-end | tip part of the driver bit of FIG. It is XX sectional drawing shown in FIG. 5B. FIG. 5B is a YY sectional view shown in FIG. 5B. FIG. 5B is a ZZ cross-sectional view shown in FIG. 5B. FIG. 6B is a sectional view taken along the line U-U shown in FIG. 6B. It is VV sectional drawing shown to FIG. 6B. FIG. 6B is a WW cross-sectional view shown in FIG. 6B. It is a figure which shows the result of the repetition test using a torque test machine. It is a figure which shows the result of the driving test using a driving test machine. It is a perspective view of the driver bit (the 1) concerning a 2nd embodiment of the present invention. It is a side view of the driver bit (the 1) concerning a 2nd embodiment of the present invention. It is a front view of the driver bit (the 1) concerning a 2nd embodiment of the present invention. It is a perspective view of the driver bit (the 2) concerning a 2nd embodiment of the present invention. It is a side view of the driver bit (the 2) concerning a 2nd embodiment of the present invention. It is a front view of the driver bit (the 2) concerning a 2nd embodiment of the present invention. It is a perspective view of the driver bit (the 1) concerning a 3rd embodiment of the present invention. It is a side view of the driver bit (the 1) concerning a 3rd embodiment of the present invention. It is a front view of the driver bit (the 1) concerning a 3rd embodiment of the present invention. It is a perspective view of the driver bit (the 2) concerning a 3rd embodiment of the present invention. It is a side view of the driver bit (the 2) concerning a 3rd embodiment of the present invention. It is a front view of the driver bit (the 2) concerning a 3rd embodiment of the present invention. It is a perspective view of a driver bit concerning a 4th embodiment of the present invention. It is a side view of a driver bit concerning a 4th embodiment of the present invention. It is a front view of a driver bit concerning a 4th embodiment of the present invention. It is a perspective view of a driver bit concerning a 5th embodiment of the present invention. It is a side view of a driver bit concerning a 5th embodiment of the present invention. It is a front view of a driver bit concerning a 5th embodiment of the present invention.

Hereinafter, a driver bit according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same parts (portions) are denoted by the same reference numerals even in different embodiments. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.
<First Embodiment>
[Construction]
FIG. 1 is a perspective view of a driver bit 10 according to a first embodiment of the present invention, FIG. 2A is a side view of the driver bit 10, and FIG. 2B is a front view of the driver bit 10. It is. 3A and 3B show a state in which the driver bit 10 is rotated by 45 ° in the bit axis direction from the state of FIGS. 2A and 2B. As shown in these drawings, the driver bit 10 is a double-headed bit in which a pair of blade edge portions 12 are formed on both ends of the main body, and the blade edge portion 12 has a cross-shaped blade in plan view. Prepare. The side view corresponds to a plan view.

In addition, the middle portion of the main body has a barrel portion 14 that is fitted into the socket portion of the rotary tool and receives the rotational force from the rotary tool. A pair of locking groove portions 16 into which members are fitted are provided.
Specifically, the body portion 14 has a hexagonal cross section, and has six R chamfered corner portions in cross sectional view and six side faces formed between the corner portions. The body portion 14 can be inserted into a hexagonal mounting hole in the socket portion of the rotary tool.

Locking groove portions 16 having a concave cross section and an arc shape are formed at both ends of the body portion 14 in the circumferential direction of the main body. In this locking groove portion 16, a spherical locking member of the socket portion projects and fits in the radially inward direction.
Further, the cross-sectional diameter of the locking groove portion 16 is smaller than the cross-sectional diameter of the body portion 14. As a result, the locking groove portion 16 acts as a torsion portion having a small torsional rigidity, can absorb the excessive load applied to the blade edge portion 12 instead of the torsion, and the durability of the driver bit 10 can be improved.

The blade tip 12 of the driver bit 10 is generally called a Phillips type, and is an inclined surface (in other words, the tip of the blade that tapers as the cross-sectional area of the blade in a plane perpendicular to the bit axis line goes to the tip. From the rear to the rear end). In addition to such a general driver bit structure, the driver bit according to the present embodiment has the following characteristic structure.

As shown in FIGS. 1 to 3A and 3B, the inclined surface of the driver bit 10 includes a first inclined surface 12A on the bit front end side and a rear end side of the blade that is continuous with the first inclined surface 12A. And the second inclined surface 12B. The second inclined surface 12B is larger in cross-sectional area of the blade in the plane perpendicular to the bit axis than the first inclined surface 12A. Note that there may be three or more inclined surfaces.

Furthermore, the first inclined surface 12A is an inclined surface corresponding to a portion that fits into the cross groove formed on the screw head, and the second inclined surface 12B corresponds to a portion that does not fit into the cross groove. It is an inclined surface.
The conventional driver bit is provided with a shape that gradually increases in thickness from the front end to the rear end of the blade at a constant inclination angle, whereas the driver bit 10 according to the present embodiment has at least two inclinations having different inclination angles. It is a great feature that it has a surface and is continuous. In addition, even if it has three inclined surfaces in the blade edge | tip of the patent document 1 mentioned above, an inclined straight line and the straight line orthogonal to a bit axis line are alternately provided continuously without an inclined surface continuing. (That is, θ described later spreads to about 90 °), the fact that the structure is greatly different will be described in a confirming manner.

Furthermore, this structural feature will be described in more detail in comparison with a comparative product. A perspective view of a driver bit 100 as a comparative product is shown in FIG. 5A and 5B are enlarged views of the distal end portion of the driver bit 10 according to the present embodiment, and FIGS. 6A and 6B are views corresponding to FIGS. 5A and 5B and are comparative products. 3 is an enlarged view of a tip portion of a driver bit 100. FIG.
The driver bit 100 which is a comparative product also has the same structure as the driver bit 10 according to the present embodiment except for the blade edge part, and includes a body part 114 corresponding to the body part 14 and a locking groove part 116 corresponding to the locking groove part 16. Prepare. The driver bit 10 is provided with a blade edge portion 12 at its tip, whereas the driver bit 100 is provided with a blade edge portion 112 at its tip.

As shown in these drawings, the cutting edge portion 112 of the driver bit 100 as a comparative product has a constant inclination angle and a shape that gradually increases from the leading end to the trailing end of the blade. The cutting edge portion 12 of the driver bit 10 according to the present invention has a first inclined surface 12A having a small inclination angle (on the bit tip side) and a wider inclination angle (on the rear end side of the cutting edge portion 12 or on the bit center portion side). ) The second inclined surface 12B is provided, and they are continuous. Since the inclination angle is set in this way, the second inclined surface 12B has a larger cross-sectional area of the blade in the plane perpendicular to the bit axis line than the first inclined surface 12A.

Referring to the cross-sectional view of the cutting edge, the cross-sectional area of the blade in the plane perpendicular to the bit axis will be described. 7A is a sectional view taken along the line XX shown in FIG. 5B, FIG. 7B is a sectional view taken along the line YY, FIG. 7C is a sectional view taken along the line ZZ, and FIG. FIG. 8B is a VV cross-sectional view, and FIG. 8C is a WW cross-sectional view. The YY line and the VV line are in the vicinity of a boundary line between a portion that fits in the cross groove formed in the screw head and a portion that does not fit in the cross groove formed in the screw head.

The XX cross section shown in FIG. 7A and the UU cross section shown in FIG. 8A are the same, and the YY cross section shown in FIG. 7B and the VV cross section shown in FIG. 8B are the same. In other words, for the part that fits into the cross groove formed on the screw head, a structure that satisfies the basic function of the driver bit, that is, the function of fitting into the cross groove and sufficiently transmitting the rotational torque to the screw. It has a cross section with. On the other hand, the ZZ cross section shown in FIG. 7C and the WW cross section shown in FIG. 8C have different cross sectional areas, and the cross sectional area of the driver bit 10 is larger than that of the driver bit 100. As a reference, a cross-sectional outline of the cutting edge portion 112 of the driver bit 100 is shown by a dotted line in FIG. 7C.

Here, the spread of the second inclined surface 12B will be described. As shown in the side view of FIG. 5A, the blade edge portion 12 has an extended line of a line representing the first inclined surface 12A and a second inclined surface in a plan view (viewed from the direction in which the blade looks like a cross shape). The acute angle θ at which the line representing 12B intersects satisfies 0 <θ ≦ 46 °. When θ = 46 °, the line representing the second inclined surface 12B is parallel to the groove of the blade edge portion 12. If θ> 46 °, it is not preferable in that it is difficult to process the second inclined surface 12B together with the groove of the blade edge portion 12.

[Durability evaluation]
The durability of the driver bit 10 according to the present embodiment having the structure of the blade edge portion 12 as described above was evaluated, and will be described below.
FIG. 9 is a diagram showing the results of the repetition test, and FIG. 10 is a diagram showing the results of the driving test. In the repeated test, a predetermined torque is applied to the driver bit 10 by pressing the blade edge portion 12 of the driver bit 10 against the test bar using a torque tester. A predetermined torque was applied, and the number of repetitions until the cutting edge 12 was broken was measured. In the driving test, a driving tester was used to drive a predetermined drill screw into a predetermined test material (predetermined stroke and predetermined time interval) and measure the number of driving until the cutting edge 12 was broken. In both tests, measurement was performed on the driver bit 10 (this product) according to the present embodiment and the driver bit 100 as a comparative product. The number of N is 5 (both product and comparative product) for both tests.

As shown in FIG. 9, as a result of the repeated test, the average of five products was 197.8 times for this product and 88.8 times for the comparative product. In this way, this product was 2.2 times more than the comparative product. As shown in FIG. 10, as a result of the driving test, the average of the five was 84.6 times for this product and 36.0 times for the comparative product. In this way, this product was more than 2.4 times the number of comparisons. Thus, the measurement result more than twice was obtained in any test.

[Function and effect]
As in the test results described above, the strength of the driver bit 10 according to the present embodiment is improved with respect to the driver bit 100 that is a comparative product. As shown in FIG. 7C, this is presumed to be caused mainly by the fact that the second inclined surface 12B on the rear end side of the blade has a larger cross-sectional area of the blade in the plane perpendicular to the bit axis than the comparative product. Is done.

That is, in the driver bit 10, since the cross-sectional area of the blade on the second inclined surface 12B on the rear end side of the blade is large, it is considered that the strength is improved compared to the comparative product. Further, in the driver bit disclosed in Patent Document 1, an inclined straight line and a straight line orthogonal to the bit axis line intersect each other at about 90 °, whereas the driver bit 10 has two different inclined angles. Since the inclined surfaces are continuous (because they are bent at 46 ° at the maximum), it is considered that stress concentration does not occur at the intersection.

Since the second inclined surface 12B is a portion that does not fit into the cross groove formed on the screw head, the first inclined surface 12A, which is a basic function of the driver bit, is fitted into the cross groove. It goes without saying that the function of sufficiently transmitting the rotational torque to the screw is satisfied.
As described above, according to the driver bit 10 according to the present embodiment, the strength of the blade edge portion 12 is improved, so that the durability of the driver bit can be improved.

<Second Embodiment>
The driver bit 20 and the driver bit 30 according to the second embodiment of the present invention will be described below. In the structure of the driver bit, since the same reference numerals are given to the portions overlapping with the above description, they will not be repeated here.
11A is a perspective view of a driver bit 20 according to one embodiment of the present embodiment, FIG. 11B is a side view thereof, FIG. 11C is a front view thereof, and FIG. 12A is a present embodiment. FIG. 12B is a side view thereof, and FIG. 12C is a front view thereof.

As shown in these drawings, the driver bit 20 is provided with a torsion portion 28 in the body portion 14 of the driver bit 10, and the driver bit 30 is provided with a torsion portion on both ends of the body portion 34 separately from the body portion 34. 38.
Since the cross-sectional diameters of these torsion part 28 and torsion part 38 are smaller than the cross-sectional diameter of the body part, the torsional rigidity is small, and the excessive load applied to the blade edge part 12 can be changed to torsion and absorbed. In addition, the durability of the driver bit 20 and the driver bit 30 can be improved.

Other structures, in particular, the structure of the blade edge portion 12 are the same as those in the above-described embodiment. For this reason, also in the driver bit 20 and the driver bit 30 according to the present embodiment, since the strength of the blade edge portion 12 is improved, the durability can be improved.
<Third Embodiment>
Hereinafter, the driver bit 40 and the driver bit 50 according to the third embodiment of the present invention will be described. In the structure of the driver bit, since the same reference numerals are given to the portions overlapping with the above description, they will not be repeated here. In general, the driver bit 40 according to the present embodiment is provided with a resin spring in the torsion portion of the driver bit 20 described above, and the driver bit 50 is resin in the torsion portion of the driver bit 30 described above. A spring is provided.

13A is a perspective view of a driver bit 40 according to one embodiment of the present embodiment, FIG. 13B is a side view thereof, FIG. 13C is a front view thereof, and FIG. 14A is a present embodiment. FIG. 14B is a side view thereof, and FIG. 14C is a front view thereof.
As shown in these drawings, the driver bit 40 includes a torsion part 48 corresponding to the torsion part 28 of the driver bit 20, and a resin spring 42 is wound around the torsion part 48. A torsion part 58 corresponding to the torsion part 38 of the bit 30 is provided, and a resin spring 52 is wound around the torsion part 58.

The cross-sectional diameters of the torsion part 48 and the torsion part 58 are also smaller than the cross-sectional diameter of the body part, and the point that the excessive load applied to the blade edge part 12 can be changed to torsion and absorbed is described above. This is the same as the embodiment.
The resin spring 42 wound around the torsion part 48 and the resin spring 52 wound around the torsion part 58 are insert-molded with the

respective driver bits

40 or 50. The resin spring 42 and the resin spring 52 are used when the driver bit 40 or the driver bit 50 is attached to the rotary tool and / or when the driver bit 40 or the driver bit 50 is removed from the rotary tool. Since the elastic force acts, the effect of facilitating the process is expressed.

Other structures, in particular, the structure of the blade edge portion 12 are the same as those in the above-described embodiment. For this reason, also in the driver bit 40 and the driver bit 50 according to the present embodiment, since the strength of the blade edge portion 12 is improved, the durability can be improved.
<Fourth embodiment>
The driver bit 60 according to the fourth embodiment of the present invention will be described below. In the structure of the driver bit, since the same reference numerals are given to the portions overlapping with the above description, they will not be repeated here. In general, the driver bit 60 according to the present embodiment is different from the above-described driver bit 40 in a resin spring mounting method (driver bit manufacturing method). In the present embodiment, a form corresponding to the driver bit 50 described above is not described, but a form corresponding to the driver bit 50 may be used.

FIG. 15A is a perspective view of a driver bit 60 according to the present embodiment, FIG. 15B is a side view thereof, and FIG. 15C is a front view thereof.
As shown in these drawings, the driver bit 60 includes a torsion portion 68 corresponding to the torsion portion 48 of the driver bit 40, and a resin spring 62 is wound around the torsion portion 68.

The cross-sectional diameters of these torsion parts 68 are also smaller than the cross-sectional diameter of the body part, and the point that the excessive load applied to the blade edge part 12 can be absorbed by being twisted is the same as in the above-described embodiment. The same. In addition, when the shape (especially inner diameter) of the resin spring is the same, the cross-sectional diameter of the torsion part 68 is smaller than the cross-sectional diameter of the torsion part 48.
The resin spring 62 wound around the torsion part 68 is not insert-molded with the driver bit 60 and is manufactured separately. For this reason, the cross-sectional diameter different from the cross-sectional diameter of the torsion part 48 of the driver bit 40 according to the third embodiment to be insert-molded is provided. The resin spring 62 manufactured separately from the driver bit 60 is expanded and fitted into the torsion part 68 from the blade edge part 12. Thus, since it is not insert molding, a gap larger than that of the driver bit according to the third embodiment is generated between the torsion portion 68 and the resin spring 62. Although there is a difference in the gap as described above, this resin spring 62 also has the effect of facilitating the attachment and / or removal of the driver bit 60 from the rotary tool, as compared with the above-described embodiment. The same.

Other structures, in particular, the structure of the blade edge portion 12 are the same as those in the above-described embodiment. For this reason, also in the driver bit 60 which concerns on this Embodiment, since the intensity | strength of the blade edge | tip part 12 improves, durability can be improved.
<Fifth embodiment>
The driver bit 70 according to the fifth embodiment of the present invention will be described below. In the structure of the driver bit, since the same reference numerals are given to the portions overlapping with the above description, they will not be repeated here. In general, the driver bit 70 according to the present embodiment is a one-head type of the driver bit 40 described above. In the present embodiment, a form corresponding to the driver bit 50 and the driver bit 60 described above is not described, but a form corresponding to the driver bit 50 (one-head type of the driver bit 50) may be used. It is possible to adopt a form corresponding to the one-head type of the driver bit 60).

16A is a perspective view of a driver bit 70 according to the present embodiment, FIG. 16B is a side view thereof, and FIG. 16C is a front view thereof.
As shown in these drawings, the driver bit 70 is a one-head type of the driver bit 40. A torsion part 78 corresponding to the torsion part 48 is provided, and a resin spring 72 is wound around the torsion part 78.

The cross-sectional diameters of these torsion parts 78 are also smaller than the cross-sectional diameters of the body parts, and the point that the excessive load applied to the blade edge part 12 can be absorbed by being twisted is the same as in the above-described embodiment. The same.
The resin spring 72 wound around the torsion part 78 is insert-molded with the driver bit 70. This resin spring 72 is also the same as the above-described embodiment in that the effect of facilitating the attachment and / or removal of the driver bit 70 from the rotary tool is facilitated.

Other structures, in particular, the structure of the blade edge portion 12 are the same as those in the above-described embodiment. For this reason, also in the driver bit 70 which concerns on this Embodiment, since the intensity | strength of the blade edge | tip part 12 improves, durability can be improved.
<Other embodiments>
The characteristic structure of the driver bit according to the present embodiment is the shape of the blade edge portion 12 (the first inclined surface 12A and the second inclined surface 12B). For this reason, the present invention is not limited to the above-described form, and if this blade edge portion 12 is provided, it may be a one-head type driver bit that does not have a torsion portion, or may be an inch bit (short bit). Absent.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The present invention can be suitably applied to a driver bit for a rotary tool, but can be suitably applied to all tools that rotate such as a screw having a cross groove formed on a screw head.

10 Driver bits (first embodiment)
12 blade edge part 12A 1st inclined surface 12B 2nd inclined surface 14 trunk | drum 16 locking groove part 20 driver bit (2nd Embodiment)
30 Driver bits (second embodiment)
40 Driver bits (Third embodiment)
50 Driver bits (Third embodiment)
60 Driver bits (fourth embodiment)
70 Driver bits (fifth embodiment)
100 Driver bits (comparative product)

Claims

A screwdriver bit having a cross-shaped blade that fits in a cross groove formed in a screw head,
The blade includes an inclined surface that tapers as the cross-sectional area of the blade in a plane perpendicular to the bit axis extends toward the tip,
The driver bit according to claim 1, wherein the inclined surface includes at least two inclined surfaces.
The inclined surface includes a first inclined surface on the bit front end side and a second inclined surface on the rear end side of the blade that is continuous with the first inclined surface,
2. The driver bit according to claim 1, wherein the second inclined surface has a larger cross-sectional area of the blade in the vertical surface than the first inclined surface.
The first inclined surface is an inclined surface of a portion that fits into the cross groove,
The driver bit according to claim 2, wherein the second inclined surface is an inclined surface of a portion that does not fit into the cross groove.
The blade has an acute angle θ at which the extension line of the line representing the first inclined surface and the line representing the second inclined surface intersect in a plan view satisfying 0 <θ ≦ 46 °. The driver bit according to claim 2 or 3, characterized in that