JP2004197908A - Screw and screwdriver bit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily fit a screwdriver bit to a screw, and to prevent the dropping of the screw from the screwdriver bit. <P>SOLUTION: A counter bored part 19 is formed on a hole 15 formed on a head part 13 of the screw 11, and a side face of the screwdriver bit 20 for fitting the screw 11, has an inclined part 24 kept into contact with an inlet end part 25 of the counter bored part 19. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a screw having a hexalobular hole that allows a driver bit to be easily fitted into the screw and does not drop from the driver bit, and a driver bit for screwing the screw.
[0002]
[Prior art]
2. Description of the Related Art Modern mechanical products such as automobiles are becoming more and more complicated year by year in their structures. Along with this, when assembling these mechanical products, simplification of the work efficiency and work method is very important in terms of cost. For example, in the case of producing automobiles, the reality is that the chassis is shared by many types of automobiles, or the same parts are used in various places, and the chassis is produced in a short period of time.
By the way, in a mechanical product constructed by assembling various parts such as an automobile, as a generally used assembling / fixing means, a screw including a screw shaft portion and a head, and a driver for screwing the screw are used. Using a bit, the driver bit is fitted into a hole in the screw head and rotated, and the screw is screwed into a counterpart material and fixed.
[0003]
However, in the industry dealing with recent machine products where the above-mentioned work efficiency is extremely important, for example, when screwing a screw into a part and fixing it, the fitting of the driver bit and the screw does not go smoothly, or the driver If the screw is removed from the bit, a time loss occurs at this point, and as a result, the overall work efficiency is reduced.
[0004]
Here, if only the screw is to be prevented from dropping from the driver bit, the hole into which the driver bit is to be fitted in the screw head may be made smaller so that the driver bit and the hole are tightly fitted. In this case, torque transmission from the driver bit to the screw is also ensured. However, if the hole is reduced in this way, it may happen that the fitting of the driver bit and the screw is not smooth.
Therefore, in order to improve work efficiency, when assembling a machine product, it is necessary to eliminate the conflicting characteristics of facilitating the fitting of the screw and the driver bit and preventing the screw from dropping from the driver bit. .
[0005]
Here, as a prior art close to the present invention, for example, a conical surface in which a certain side wall is deviated from a cylindrical surface at a position radially outward or radially inward in order to keep contact with a driving tool during rotational driving. A screw with an end of a screw drive and a recessed drive formation formed at this end, on the conical surface of a cone that is on top and otherwise tapered inside the recess, There has been disclosed a screw rotating tool having a shape corresponding to a screw drive forming portion (for example, see Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 05-196020 (Pages 1 to 3, FIGS. 1 and 2)
[0007]
[Problems to be solved by the invention]
The hole in the head of the screw described in Patent Document 1 is referred to as a hexalobular hole. The basic form of this hole is shown in FIG. In this figure, the screw shaft portion 3 of the screw 2 and the upper head portion 4 are cut away so that the shape of the hexalobular hole 1 can be clearly understood. This is a form in which six ridges 5 protruding outward and valleys 6 protruding outward are formed alternately.
FIG. 6 shows a driver bit 7 for the screw 2 having the hexalobular hole 1, a concave portion 8 corresponding to the crest 5 of the hole 1, and a convex portion 9 corresponding to the valley 6 of the hole 1. Are alternately formed six by two. The driver bit 7 is formed to be slightly smaller than the hole 1 so that the driver bit 7 can be inserted into the hexalobular hole 1. When the driver bit 7 is inserted into the hole 1, a slight gap is formed between the driver bit 7 and the inner surface of the hole 1.
[0008]
The hexalobular hole 1 and the driver bit 7 having the above-described shapes have characteristics such as transmitting torque efficiently, hardly deforming the hole 1 due to stress concentration and wedge action, and hardly breaking the driver bit 7. Have.
However, although the hexalobular hole 1 and the driver bit 7 are effective for torque transmission, since the hexalobular hole 1 is slightly smaller than the driver bit 7 as described above, it is necessary to insert the driver bit 7 into the hexalobular hole 1. Although it is easy to do so, when the driver bit 7 is fitted into the hexalobular hole 1 of the screw 2 and the screw 2 is taken to the screwing target portion with the screw 2 attached, the screw 2 comes off from the driver bit 7 on the way. .
[0009]
The present invention has been made in view of the above circumstances, and its purpose is to easily fit a driver bit into a hexalobular hole formed in the head of a screw, and when the driver bit is fitted into the hexalobular hole, it becomes difficult to remove the screw. It is an object of the present invention to provide a screw and a driver bit which can prevent the screw from easily falling off the driver bit.
[0010]
[Means for Solving the Problems]
In other words, the present invention is a screw having a hole for inserting a driver bit into a head, and the hole is formed by alternately forming six valleys projecting outward and six peaks projecting inward. In the screw formed as the hexalobular hole, a hexagonal portion of the hexalobular hole is a counterbored portion extending from the entrance of the hexalobular hole to an intermediate position in the depth direction, and is located deeper in the valley than at the top of the peak. In addition, a counterbore portion is formed which is located closer to the top of the crest than to the innermost portion of the valley (claim 1).
[0011]
Further, the present invention is a driver bit fitted into the hexalobular hole to rotationally drive the screw, the driver bit having a concave portion and a convex portion corresponding to the peak and the valley of the hexalobular hole alternately, At a portion of the concave portion separated from the distal end to the base end side (the side that applies the rotational torque), an inclined surface portion whose projection amount increases toward the base end side is protruded, and when fitted into the hexalobular hole, The inclined surface portion is in contact with a counterbore portion of the hexalobular hole of the screw (claim 2).
[0012]
According to the above configuration, the entrance portion of the hexalobular hole is widened by the counterbore, so that the driver bit can be more easily inserted. In addition, since the driver bit is provided with an inclined surface portion, when the driver bit is fitted into the hexalobular hole, the inclined surface portion comes into contact with the counterbored portion of the hexalobular hole and bites there. Hard to come off.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 4, the screw 11 includes a screw shaft 12 and a head 13. The screw shaft 12 has a screw thread 14, and the head 13 has a hole 15. As shown in FIG. 3 (a), the hole 15 has a so-called hexalobular shape in which six valleys 16 protruding outward from the center of the hole 15 and six peaks 17 protruding inward are formed alternately. It is a hole. Each of the valleys 16 and the peaks 17 has an arcuate curved surface and is smoothly connected.
[0014]
Here, the peak portion 17 has a counterbore portion 19 extending from the entrance 18 of the hole 15 to a point in the depth direction. The inner surface 19a of the counterbore 19 has an arc shape, and the inner surface 19a of the counterbore 19 of each peak 17 is included in one cylindrical surface. The radius of one cylindrical surface enclosing the inner side surface 19a of each counterbore 19 is larger than the radius from the center of the hole 15 to the top of the peak 17, and the innermost part of the valley 16 from the center of the hole 15 It is set smaller than the radius up to. Note that the height h of the counterbore portion 19 is desirably not more than half the depth H of the hole 15.
[0015]
As shown in FIG. 1 (b), a driver bit 20 for rotatingly driving the screw 11 and screwing the screw 11 into a mating member has a conical shape or a tip 21 close to the conical shape, and FIG. The projections 22 and the depressions 23 corresponding to the valleys 16 and the peaks 17 of the holes 11 are formed alternately. These convex portions 22 and concave portions 23 also form an arcuate curved surface and are smoothly connected. Further, a portion extending from the distal end portion 21 of the concave portion 23 formed on the side surface of the driver bit 20 to the proximal end side (the side that applies the rotational torque, the lower side in FIG. 1B), and extending in the proximal end direction. As shown in FIG. 2, an inclined surface portion 24 whose projection amount gradually increases toward the base end side is protrudingly provided. The inclined surface portion 24 forms a part of a conical surface. The radius R1 on the proximal side is larger than the radius R of the counterbore portion 19, and the radius R2 on the distal side is smaller than the radius R of the counterbore portion 19. ing.
[0016]
When the screw 11 configured as described above is rotated by the driver bit 20 and screwed into a mating member, first, the driver bit 20 is inserted into the hole 15 formed in the head 13 of the screw 11. At this time, the driver bit 20 can be easily inserted into the hole 15. In other words, the entrance 18 of the hole 15 has a form in which the tip of the valley 16 protrudes outward from one circle connecting the six counterbore portions 19, so that only the tip of the protrusion 22 of the driver bit 20 is provided. If the tip of the convex portion 22 of the driver bit 20 is made to slide against the inner surface 19a of the counterbore portion 19, the tip of the convex portion 22 naturally has a hole. Since the driver bit 20 enters the front of the valley 16 of the fifteen, the driver bit 20 can be easily inserted into the hole 15.
[0017]
When the driver bit 20 is inserted into the hole 15, as shown in FIG. 3 (b), the tip 21 is slightly in front of the bottom of the hole 15, and the slope formed on the side surface of the driver bit 20. The surface 24 makes a so-called line contact with the entrance end 25 of the counterbore 19. Then, since the inclined surface portion 24 comes into strong contact with the counterbore portion 19 due to its wedge action, the screw 11 is held by the driver bit 20, and the screw 11 may come off from the driver bit 20 while going to the screwing target portion. Absent.
[0018]
Further, the torque transmission from the driver bit 20 to the screw 11 is performed when the convex portion 22 and the concave portion 23 of the driver bit 20 come into contact with the valley portion 16 and the peak portion 17 of the hole 15 (hexalobular hole). In the present embodiment, since the counterbore 19 is provided at the peak 17 of the hole 15, the contact area between the driver bit 20 and the hole 15 is reduced by the presence of the counterbore 19. However, the counterbore portion 19 does not exist in the mountain portion 17 over the entire depth direction of the hole 15, but is provided only in the middle of the hole 15 from the entrance 18 to the bottom. Further, the counterbore portion 19 is not provided up to the deepest portion of the valley portion 16. Therefore, when the driver bit 20 is fitted into the hole 15, a decrease in the contact area between the concave portion 23 of the driver bit 20 and the crest 17 of the hole 15 can be minimized. The portion 22 and the valley portion 16 of the hole 15 are entirely in contact with each other and are caught, so that a reduction in the efficiency of torque transmission from the driver bit 20 to the screw 11 can be further suppressed.
[0019]
By the way, the surface of the screw 11 is subjected to a surface treatment, such as dacrotized, which is immersed in a treatment liquid and then heat-treated. In this process, after immersing the screw 11 in the processing liquid, excess processing liquid is blown off by centrifugal force in order to equalize the processing liquid attached to the surface of the screw 11. Here, since the hole 18 of the screw 11 has its inlet 18 widened by the presence of the counterbore 19, the processing liquid remaining in the hole 15 is easily blown out of the hole 15 by centrifugal force. As a result, the treatment liquid is more uniformly applied not only to the screw shaft portion 12 of the screw 11 and the side surface of the head portion 13 but also to the inside of the hole 15. Similar effects can be obtained when plating is performed.
[0020]
When the counterbore 19 is provided in the hole 15, the weight of the screw 11 itself can be reduced, and the life of the punch can be extended. That is, the hole 15 of the head 13 of the screw 11 is generally formed by cold casting using a punch, but the hole 11 is configured such that the area of the inlet 18 is larger than the area of the bottom. Therefore, the shape of the punch is also substantially the same, that is, the shape of the root portion is larger than that of the tip portion in cross section. Therefore, the load applied to the punch when the hole 15 is formed in the head 13 of the screw 11 with the punch can be received at the root of the punch having a large cross-sectional area, and the load can be dispersed, and It leads to a longer life.
[Brief description of the drawings]
1A and 1B show one embodiment of the present invention, in which FIG. 1A is a plan view of a driver bit, FIG. 1B is a side view, FIG. 2 is a perspective view of a driver bit, and FIG. FIG. 4B is a plan view of a hole formed in the portion, and FIG. 4B is a cross-sectional view showing a fitting state between the driver bit and the screw taken along line AA in FIG. FIG. 5 is a perspective view of FIG. 4 showing a conventional example. FIG. 6 is a view of FIG.
In the figure, 11 is a screw, 13 is a head, 15 is a hole, 16 is a valley, 17 is a peak, 19 is a counterbore, 20 is a driver bit, 22 is a convex, 23 is a concave, and 24 is an inclined surface. It is.

Claims (2)

A screw formed with a hole for inserting a driver bit into the head, the screw being a hexalobular hole formed by alternately forming six valleys protruding outward and six ridges protruding inward. At
A pit portion extending from the entrance of the hexarobula hole to an intermediate position in the depth direction at the crest of the hexarobula hole. A screw formed with a counterbore located closer to the top of the crest than the portion. A driver bit fitted into the hexalobular hole for rotationally driving the screw according to claim 1, wherein the driver bit has a concave portion and a convex portion corresponding to a valley and a peak of the hexalobular hole alternately,
At the part of the concave portion separated from the distal end to the proximal end side, an inclined surface part whose projection amount gradually increases toward the proximal end side is protruded, and when fitted into the hexalobular hole, the inclined surface part is the screw of the screw. A driver bit, which is in contact with a counterbore of a hexalobular hole.

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