JPH0260470B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides a cross-shaped recess that is inserted into a cross-shaped recess formed on the top surface of a screw head, and that attaches or detaches a screw to a member to be screwed by transmitting rotational torque to the screw. Concerning improvements in the bit structure of a hole driver. (Prior Art) Conventionally, as this type of bit structure, a structure corresponding to a Phillips cross recess has been widely used. This is because the Phillips cross recesses for screws, as shown in Figures 6 to 8, have been standardized based on the national standards of each country and are the most widely used around the world. This is also because it has the following excellent advantages. First, it has good fitability with the Phillips cross recess. Second, it has good grip with the Phillips cross recess. Thirdly, when using screws of various nominal sizes, fewer types of driver bits are required and productivity is excellent. (Problems to be Solved by the Invention) By the way, if the bit structure of the cross-recess driver molded to correspond to the Phillips cross-recess is explained based on FIGS. The angle r' D (FIG. 6 d) formed by the tips of both side surfaces 2, 2 of the wing section 1 of bit B in the insertion direction is the angle r' _D (FIG. 6 d) of both side surfaces 12,
12 is formed to be smaller than the angle r' formed in the depth direction, and furthermore, the bit B and the driver center line O
Since the angle α' of the trough 3 with respect to the cross recess 10 is set smaller than the angle of the trough 14 with respect to the center line in the depth direction (which coincides with the driver center line O), When inserted into the cross recess 10, as shown in FIG.
The trough 3 at the tip in the insertion direction and the bottom 1 of the cross recess 10
The three adjacent troughs 14 come into close contact with each other, resulting in what is called "sticking". When the screwdriver is rotated again, the rotation start state shown in FIGS. 7a to 7c is changed to the torque transmission state shown in FIGS. 8a to 8c. Here, the bit B contacts the vicinity of the bottom part 13 of the cross recess 10 only at the insertion tip of the side surface 2 of the wing part 1, and as shown in FIG. 8a, the bit B and the cross recess 1
The contact surface pressure with 0 increases in a quadratic curve toward the tip of the bit B in the insertion direction. Therefore, with the recent progress in mass production assembly methods, the following drawbacks have been pointed out in the bit structure of the conventional Phillips cross recess screwdriver, and there is a strong demand for improvement. The first is that, as is often the case with automatic screw tightening machines that have come into widespread use in recent years, the good grip of the Phillips cross recess has the opposite effect, causing bit B to be pulled out from the cross recess 10 after tightening. In some cases, the bit B may become stuck in the cross recess 10, causing the driver body to be pulled out of the socket, or the product to be lifted together with the bit B. Secondly, since the tip of the bit B in the insertion direction contacts the cross recess 10, the tightening torque of the screwdriver is concentrated on the tip of the side surface 2 of the wing portion 1 of the bit B in the insertion direction during tightening work. , an extremely large surface pressure is generated there, and this surface pressure causes the tip of the wing portion 1 of the bit B in the insertion direction and the bottom 13 of the cross recess 10 to
The surrounding area is easily deformed and damaged, reducing the lifespan of bit B. This is the biggest reason why bit B wears out quickly. Thirdly, as wear and torsional deformation near the tip of the bit B in the insertion direction progresses, a so-called cam-out phenomenon occurs in which the bit B gradually lifts up and slips out of the cross recess 10 due to vibrations when the driver rotates. At this time, a reaming phenomenon occurs in which the tip of the wing part 1 of the bit B scrapes the valley part 14 of the cross recess 10, making it difficult to remove and retighten the screw, and once the screwdriver cams out, it becomes unusable. It has the disadvantage of becoming. Fourthly, when tightening the screw, a large thrust force must be applied to bit B to prevent it from coming out, which has the disadvantage of increasing operator fatigue. (Object of the Invention) The present invention has been devised in view of the current situation, and its purpose is to provide a screw with a screw cross recess without impairing the above-mentioned advantages of the Phillips cross recess. It can prevent holes from sticking and sticking. Deformation and damage to the tip of the bit wing in the insertion direction and near the bottom of the cross recess can be avoided. Prevents the come-out phenomenon and enables long-term use of the driver. Eliminates thrust application to prevent come-out,
Reduce worker effort. This is an attempt to provide a bit structure for a cross-recessed screwdriver. (Structure of the Invention) In order to achieve the above object, the present invention provides a screw with a cross-shaped cross section having alternating wing portions and valley portions so as to be inserted into a cross recess formed in the head of a screw. In the bit structure of a screwdriver for a cross recess, the angle formed by the tip in the insertion direction on both sides of each wing of the bit is the angle formed by the depth direction on both sides of each wing forming the cross recess. In addition, the angle of the trough with respect to the center line of the driver in the bit is set larger than the angle of the trough with respect to the center line in the depth direction of the cross recess. (Function) In this invention based on the above configuration, when the bit of the screwdriver is inserted into the cross recess on the top surface of the head of the screw and the bit of the screwdriver is rotated, the side surface of the wing part of the bit is inserted into the cross recess of the screw. Surface contact occurs only at the side surfaces of the blades near the top surface, and rotational torque is transmitted. (Example) Hereinafter, the present invention will be described in detail based on an example shown in the accompanying drawings. 1 to 3 show an embodiment of the present invention designed to prevent the bit B of the cross-recessed screwdriver from coming into contact with the Phillips cross-recess 10 of the screw. A bit B is formed at the tip of the driver body D in the insertion direction (hereinafter referred to as the tip),
The other end has a connection part D _r that is connected and held with the driver grip part or the driver body grip part of an automatic screw tightening machine.
is formed. The bit B has a cross-shaped cross section as shown in FIG.
It has cross-shaped wing parts 101 spaced apart by degrees, and each of these wing parts 101 has tapered side surfaces 10 extending in the axial direction, that is, in the direction of insertion into the cross recess 10 in FIG.
2, 102, and a conical outer circumferential surface 104 that connects the two side surfaces 102, 102. The angle r _D (Fig. 3 d) formed by the tips of both side surfaces 102, 102 of each wing portion 101 is the depth formed by both side surfaces 12, 12 of the wing portion 11 in the cross recess 10 of the screw S. The direction angle r is set larger than the direction angle r. Furthermore, bit B and driver center line O
The angle α of the trough 103 relative to the trough 103 (this figure 3a is not a cross section along the trough 103 of bit B, so it is not an exact angle, and the exact angle α in figure 2b) is set in the cross recess. 10, which is set larger than the angle β of the valley portion 14 with respect to the center line in the depth direction (not shown since it coincides with the driver center line O). In Bit B, the angle formed by the outer circumferential surfaces 104 of the wing sections 101 located in the 180° direction is approximately equal to the angle formed by the outer circumferential surfaces 15 of the wing sections 11 located in the same direction of the cross recess 10. , is set slightly larger. Next, the operation of the above embodiment will be explained. First, when the bit B is inserted into the cross recess 10 of the screw S, the outer circumferential surface 104 of each wing portion 101 comes into close contact with the corresponding outer circumferential surface 15 of each wing portion 11 of the cross recess 10, as shown in FIGS. 3a and 3b. or contact (Figure 3a is the top surface 1
Only the 6th side is in contact) and stops (insertion is complete). At this time, the trough 103 at the tip of the bit B,
Since the angle α>angle β holds between the trough 14 on the bottom 13 side of the cross recess 10 and the angle α as described above, the two are in a non-contact state, facing each other with a predetermined gap therebetween, as shown in FIG. 3c. Also, both side surfaces 10 of each wing portion 101 of Bit B
2, 102 are both side surfaces 1 of the wing portion 11 of the cross recess 10
It is separated from 2 and 12. Then, when the driver body D is rotated, the fourth
As shown in Figures a and b, immediately after the rotation starts,
Drive side side surface 102 (fourth
The right side in the figure) is one side 12 of the wing part 11 of the cross recess 10, which makes contact near the top surface 16 of the head of the screw S, but the tip of the bit B is c in the figure.
As shown, the valley 103 and the valley 14 remain in non-contact. On the other hand, while the driver main body D is rotating, the side surface 102 of the wing section 101 of the bit B and the side surface 12 of the wing section 11 of the cross recess 10 are connected to the top of the head of the screw S, as shown in FIGS. 5a and 5b. Surface contact is made in area B near the surface 16. The surface pressure in this area B is the fifth
As shown in FIG. , the rotational torque of the driver body D is transmitted to the screw S, and the trough 103 at the tip of the bit B and the trough 14 of the cross recess 10 on the bottom 13 side are not closely connected as shown in Figure c. The condition is maintained. Therefore, when transmitting rotational torque, it is possible to avoid stress concentration at the tip of the wing section 101 of the bit B, and the bit B is less likely to be torsionally deformed or worn out. The come-out phenomenon of B can be effectively prevented. As a result, bit B of driver body D
It is possible to significantly improve the lifespan of the
Since the plating applied to the surfaces of the bit B and the cross recess 10 will not peel off due to deformation of the bit B and the cross recess 10 during tightening, it is possible to prevent the occurrence of rust caused by these. Furthermore, it is no longer necessary to apply an excessive thrust to prevent the cam-out phenomenon when the driver body rotates, unlike in the past, and it is possible to reduce operator fatigue and significantly improve work efficiency. Furthermore, since the sticking (sticking) phenomenon between the tip of the wing part 101 of the bit B and the wing part 11 of the cross recess 10 on the bottom 13 side is effectively suppressed, the tightening of the screw S is prevented. Upon completion, the bit B portion can be easily pulled out from the cross recess 10. In addition, the above-mentioned angle α' (Fig. 6a) in the conventional driver bit based on the JIS standard, and the above-mentioned angle r' _D [Fig. d] and the angle α, r _D [third
A comparison between Figures a and d] shows the results shown in the following table.

【table】

[Table] (Effects of the Invention) Since the present invention is constructed as described above, while the driver body is rotating, the side surfaces of the wing portion of the bit and the side surfaces of the wing portion of the cross recess are such that the side surface of the wing portion of the screw head is The rotating torque of the driver body is transmitted to the screw through surface contact only near the top surface, and the trough of the bit, which is the tip in the insertion direction, and the trough of the cross recess, which does not touch the bottom side. The condition is maintained. Therefore, when transmitting rotational torque, it is possible to avoid stress concentration at the tip of the blade in the insertion direction, and the bit is less likely to be torsionally deformed or worn out. The come-out phenomenon can be effectively prevented. As a result, the life of the bit on the driver body can be greatly improved, and the plating applied to the surface of the bit and cross recess will not peel off due to deformation of the bit and cross recess during tightening. It is also possible to prevent the occurrence of rust caused by. Furthermore, it is no longer necessary to apply an excessive thrust to prevent the cam-out phenomenon when the driver body rotates, unlike in the past, and it is possible to reduce operator fatigue and significantly improve work efficiency. Furthermore, since the sticking phenomenon between the wing part of the bit, which is the tip in the insertion direction, and the wing part, which is the bottom part, of the cross recess, is effectively suppressed, the bit part is inserted into the cross recess when tightening the screw is completed. It can be easily pulled out.

[Brief explanation of the drawing]

1 to 5 show embodiments of the present invention.
The figure is a front view of the driver body, Figure 2 a is a bottom view of the driver body, Figure 2 b is a cross-sectional view taken along the line aX in Figure 2, figure 2 c is a cross-sectional view taken along the line bY-Y in Figure 2, and Figure 3
Figure a is a side view of the bit inserted into the cross recess.
Figures 3b and c are cross-sectional views in the M plane and _Gg plane of Figure 3a, Figure 3d is A-A in Figure 3a.
Line sectional views, Figures 4a to 4c are sectional views showing the relationship between the screwdriver bit and the cross recess when the bit starts rotating, and Figures 5a to 5c are cross sectional views showing the relationship between the screwdriver bit and the cross recess during rotation. 6 to 8 show the conventional example, FIG. 6 a is a side sectional view of the bit inserted into the cross recess, and FIGS. 6 b and c are the same as in FIG. 6 a. 6d is a sectional view taken along the line AA in _FIG . 6a, and FIGS. 7a to 7c are the relationships between the screwdriver bit and the cross recess at the start of rotation. FIGS. 8a to 8c are sectional views showing the relationship between the screwdriver bit and the cross recess during rotation of the bit. Explanation of symbols, B...Bit of screwdriver for cross recess, D...Driver body, S...Screw, 10...Cross recess, 11...Wing of cross recess, 12, 12...Both sides of wing of cross recess, 16... Top surface of screw head, 101...
Wing part of the bit, 102,102...Both sides of the wing part of the bit, _rD ...Angle of the tip of both sides of each wing part of the bit in the insertion direction, α...Angle of the trough of the bit with respect to the center line of the driver , γ...The angle formed by the bottom side of both sides of each wing of the cross recess, β...The angle of the valley with respect to the center line of the cross recess.

Claims (1)

[Scope of Claims] 1. A bit structure of a cross-recessed screwdriver having a cross-shaped cross-section and having alternating wing portions and valley portions so as to be inserted into a cross-recessed recess formed on the top surface of the head of a screw, The angle formed by the tip in the insertion direction on both sides of each wing of the bit is set to be larger than the angle formed by the depth direction on both sides of each wing forming the cross recess, and A bit structure of a cross-recessed screwdriver, characterized in that the angle of the trough with respect to the center line of the driver is set larger than the angle of the trough with respect to the center line in the depth direction.