JP2009185997A - Head driving hole of threaded component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a driving hole surely engaging an engaging groove with a driver bit in an early stage of fastening. <P>SOLUTION: In a screw which is constituted from a head 2 and a base 3 integrally formed with this, and forms a screw-thread 5 in the base 3, a driving hole 4 is formed in a center of the head 2, furthermore plural lines of engaging grooves 10 is formed in a radial direction from the center of this driving hole 4, additionally in a surface of a hill section 20 formed between other engaging grooves 10 adjacent to this engaging groove 10, a screwing rotating direction side hill section 20 is slanted at a slant angle (θ) toward bearing surface side so that the screwing rotating direction side may become deeper. Moreover, since this slant direction faces a direction parallel to a center line of the engaging groove 10 located at a screwing direction side of the hill section 20 in the driving hole, the head is prevented from being damaged when a screw small in nominal diameter is screwed with an automatic screwing machine, and an engaging blade is surely fitted to the engaging groove at the time of fastening. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a screw for fastening a component to a workpiece with a predetermined fastening force, and in particular, the engagement between a driver bit that transmits a driving force to the head during screw fastening and a screw driving hole is an engagement groove of the screw. The present invention relates to a head drive hole for a screw part that can be reliably engaged without crushing.

  2. Description of the Related Art Screws having a relatively small nominal diameter are used in electrical products such as mobile phones, personal computers, and portable music players, automobile parts, and the like that have been widely used in recent years because of their weight reduction, thickness reduction, and size reduction. As such a screw, a screw stipulated mainly in JIS (Japanese Industrial Standard) is adopted, and the head shape of the screw having a small nominal diameter as described above is the same as shown in FIG. It has a shape. FIG. 9 shows a cross-recessed screw 101, and an engagement groove 110 is formed on the head 102 in four radial directions with respect to the center of the screw 101, and a hill portion between these grooves 110. The contour of 120 is the shape of the wall that forms this groove, and the blade of the driver bit engages with this groove to transmit the screw tightening driving force. It has become.

  In addition to the cross-shaped drive hole, such a hill portion is formed in the same manner, for example, in a screw having a Y-shaped engagement groove in which a screw cannot be loosened with this + driver bit, that is, a so-called tamper-proof screw. Is done. This screw is generally used in a place that is loosened by a + driver bit and cannot be used to touch the inside of the screw. The shape of the head drive hole is a cross-shaped drive hole that extends from the center of the screw. The only difference is that the Y-shaped drive holes are in three directions compared to the four radial directions, and both have hills formed between the engaging grooves.

  Therefore, in order to engage the driver bit with the screw drive hole, especially when performing screw tightening work with an automatic screw tightening machine, the driver bit is simultaneously brought into contact with the screw head and the driver bit is rotated. Although the engagement blade of the driver bit is engaged with the engagement groove of the screw, the center of the screw and the center of the driver bit are slightly shifted at the initial stage of engagement, or the engagement blade of the driver bit is driven. If it does not fit in the engagement groove of the hole, the corner of the engagement groove is often crushed. In particular, this phenomenon occurs remarkably when the screw is small.

Further, as a prior art, there is a screw disclosed in Japanese Utility Model Publication No. 63-26566. This relates to a screw used to fix a plurality of members, and relates to a driving screw that can omit the step of previously drilling a screw pilot hole. This is to prevent damage. For this purpose, a projecting portion is formed in the hole portion, and a downward inclined surface inclined toward the bottom portion is formed on both sides from the ridge portion, and this guides the driver bit to be fitted when driven.
Japanese Utility Model Publication No. 63-26566

However, in such a conventional example, in the case of the drive hole defined in JIS, as already described, in the fastening operation using the manual driver bit, the engagement blade and the engagement groove are fitted together and then screwed. Since the work is performed, the drive hole is not crushed at the initial stage of screw tightening, but in an automated assembly factory using machines such as assembly work lines, an automatic screw tightening machine is used. Easily crushed. In particular, a screw having a small nominal diameter has a problem that the drive hole is crushed and the screw cannot be tightened with a predetermined fastening torque. In addition, when the shape of the hole employed in the driving screw is used, the engagement blade of the driver bit and the engagement groove of the drive hole are relatively easily engaged at the initial stage of screw tightening. The purpose is to prevent damage to the peripheral edge of the cross groove at the time of driving, so it is only necessary to form an inclined surface on both sides from the protruding portion to guide the engagement groove, and screw tightening work In this case, this interferes with the torque transmission. In order to solve this problem, a large thrust is required to prevent the driver bit from coming out of the drive hole during screw tightening. For this reason, there is a problem that the work is dented or damaged.

  An object of the present invention is to obtain a drive hole that solves such problems and ensures the engagement between the engagement groove and the driver bit at the initial stage of screw tightening.

  An object of the present invention is a screw having a head 2 having a drive hole 4 and a leg 3 integral therewith, and a screw 5 formed on the leg 3, and a head at the center of the head 2. A drive hole 4 is formed from the front surface side to the leg 3, a plurality of engagement grooves 10 are formed radially from the center of the drive hole 4, and another engagement groove adjacent to the engagement groove 10. In the surface of the hill portion 20 formed between the hill portion 20 and the hill portion 20, the hill portion 20 on the screw tightening rotation direction side is inclined at an inclination angle (θ) toward the seat surface side so that the screw tightening rotation direction side becomes deep. And this inclination direction is achieved by providing the head drive hole of the screw component which becomes a direction parallel to the centerline of the engaging groove 10 located in the screw loosening direction side of the hill part 20.

    In addition to the above-described configuration, the object of the present invention is to deepen as the outer periphery of the hill 20 positioned between the radial ends of the engaging grooves 10 adjacent to each other moves in the screwing rotation direction. Since the drive hole 4 having the outer peripheral wall 21 is provided, the driver bit always tends to coincide with the center of the screw. Further, the engagement groove is formed from the engagement wall 11 on the side engaged with the engagement blade 31 of the driver bit 30 at the time of screw tightening from the bottom surface 12 of the engagement groove 10 than the engagement wall 11 on the side engaged when the screw is loosened. Since the height is high, the screw tightening torque is stably transmitted.

  In addition, the inclination angle (θ) is an angle larger than 8 ° 32 ′ and smaller than 17 ° with respect to the plane perpendicular to the axis of the screw 1, so that when the driver bit contacts the screw and a slight thrust is applied. The engagement blade of the driver bit can surely fit into the engagement groove.

  According to the present invention, there is no fear that the engagement blade of the driver bit crushes the drive hole of the screw head at the initial stage of screw tightening in the automatic assembly work like the screw drive hole specified in JIS. When a screw with a small nominal diameter is tightened with an automatic screw tightener, damage to the head is avoided. In addition, since the hill portion between the engagement grooves is inclined so that the screw tightening direction side is deep, the engagement blades are surely fitted into the engagement grooves during screw tightening. Furthermore, since an outer peripheral wall inclined toward the center is formed around the hill, the screwdriver bit can always coincide with the center line of the screw drive hole during screw tightening. In addition, since the engaging wall of the engaging groove has the same height as the conventional drive hole on the side to be engaged during screw tightening, there is no problem in transmitting the screw tightening torque. In addition, the inclination angle is set to an optimum inclination angle at which the engagement blade is guided to the engagement groove only by the contact of the engagement blade of the driver bit with the hill portion of the screw head, even if little thrust is applied. Therefore, even if the screw has a small nominal diameter, there is a specific effect such as obtaining a stable screw tightening action.

  The best mode for carrying out the present invention will be described below with reference to FIGS. 1 and 2, reference numeral 1 denotes a screw composed of a head 2 and a leg 3 formed integrally therewith. The head 2 is screwed to a screw 1 from a driver bit 30 (see FIG. 6). A drive hole 4 for transmitting force is formed. A screw thread 5 is formed on the leg 3 integral with the head 2 from the vicinity of the seat surface 6 of the head 2 to the tip of the leg 3, and the leg 3 has a circular cross section. . A conical neck 7 is formed between the leg 3 and the head 2 and the leg side is thin and the head side is thick. The tip of the drive hole 4 of the head 2 has a substantially conical hole shape. The neck 7 has been reached.

  As shown in FIG. 3, the drive hole 4 has its center on the center line of the screw 1, and the drive hole 4 is formed from the surface side of the head 2 to the leg 3. A plurality of engagement grooves 10 are formed at equal intervals in the circumferential direction in the radial direction from the conical hole 8 at the center of the drive hole 4, and these engagement grooves 10 are formed as shown in FIG. A hill portion 20 is formed between another engaging groove 10 that is adjacent to each other. In this embodiment, the hill portion 20 is formed between the engagement grooves 10 because the engagement grooves 10 are Y-shaped in this embodiment. As shown in FIGS. 4 and 5, the hill portion 20 in the slope is inclined at an inclination angle (θ) toward the seating surface so that the screwing rotation direction side becomes deeper. Moreover, as shown in FIG. 2, this inclination direction is a direction parallel to the center line of the engagement groove 10 located on the screw loosening direction side of the hill portion 20.

  It is sufficient that the inclined hill portion 20 is inclined so that the screw tightening side is deep from the head surface. The optimum angle (θ) of this angle is the minimum angle, that is, the head of the screw 1. If the tip of the driver bit 30 or the engagement blade 31 is in contact with the part 2, the angle is such that the thrust starts even if almost no thrust (force that presses the driver bit toward the workpiece) is applied. It becomes like this. Here, it is conventionally known that the friction coefficient μ of a general screw 1 is about 0.15, and the maximum angle at which an object on a slope can be stopped is (θ), and the weight (or thrust) of the object ) Is Mg, it is balanced by Equation 1 (see FIG. 8).

The angle (θ) obtained from this is tan ⁻¹ μ, which is about 8 ° 32 ′. As a result, if the angle of the slope of the hill portion 20 exceeds 8 ° 32 ', the object slides on the slope, so this is the minimum angle for sliding.

  On the other hand, it is best to set the maximum angle, which is the upper limit of the optimum angle, to a value smaller than the tip angle of the driver bit 30 (18 ° ± 1 ° which is an angle defined in JIS). By setting the optimum angle (θ) of the slope in the range of 8 ° 32 ′ to 17 ° in this way, the slope of the hill portion 20 where the tip of the driver bit 30 is inclined as shown in FIG. When the angle exceeds the upper limit of the optimum angle (θ + α), the angle of the slope of the hill portion 20 where the tip of the driver bit 30 is inclined as shown in FIG. Therefore, the range of the angle is the optimum angle. In addition, by tilting within this angle range, the inner wall on the center side of the hill is formed to a sufficient height, and there is no hindrance in fitting (biting) with the driver bit.

  Furthermore, an outer peripheral wall 21 that is deeper along the outer periphery of the hill portion 20 and moves in the screw tightening rotation direction is formed between the radial ends of the engaging grooves 10 adjacent to each other. Since the outer peripheral wall 21 has a conical shape, when the tip of the driver bit 30 touches this portion, the driver bit 30 is also subjected to a moving action toward the center of the screw 1.

  In addition, the upper surface of the hill portion 20 is on the side where the engagement blade 11 of the driver bit 30 that fits into the engagement groove 10 and the engagement wall 11 that is engaged when the engagement groove 10 is screwed are engaged when the screw is loosened. Since the height from the bottom surface 12 of the engagement groove 10 is higher than the joint wall 11, the transmission of the screw tightening torque is stabilized.

  When screwing the screw 1 configured in this way, as shown in FIG. 6, the driver bit 30 is pressed so as to coincide with the conical hole-shaped drive hole 4 formed in the head 2 of the screw 1. At this time, the engagement blades 31 of the driver bit 30 do not necessarily coincide with and engage with the engagement groove 10 of the screw 1, but the tip of the driver bit 30 is screwed in the screw tightening direction due to the slope of the hill portion 20 on the head surface. Therefore, the engagement blade 31 is fitted in the engagement groove 10. Further, since the engagement wall 11 in the screw tightening direction of the engagement groove 10 is higher than the engagement wall 11 in the screw loosening direction from the bottom surface of the engagement groove, the engagement blade 31 slides out of the engagement groove 10. It will fit without.

  Thus, when the screw tightening torque of the driver bit 30 is transmitted to the drive hole 4 of the screw 1, the leg portion 3 of the screw 1 is screwed into the work (not shown). When the screw 1 is screwed in by a predetermined amount and the head seating surface 6 is seated on the work, the screw tightening is completed. In this embodiment, the drive hole 4 having the Y-shaped engagement groove 10 on the surface of the head 2 has been described. However, the drive hole having the cross-shaped engagement groove shown in the prior art is formed in the same manner. Needless to say, similar effects can be obtained.

It is a front view which shows one Example as embodiment of this invention. It is a left view of FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 is a cross-sectional view of the main part of the line BB in FIG. 2. FIG. 3 is a partial enlarged cross-sectional view taken along line CC in FIG. 2. It is principal part sectional drawing which shows the relationship between this invention and a driver bit. This is an action showing the sliding state of the inclined surface and the driver bit. It is explanatory drawing which shows the action state of the force in this invention. It is principal part sectional drawing which shows the prior art example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw 2 Head 3 Leg 4 Drive hole 5 Screw thread 6 Seat surface 7 Neck part 8 Conical hole 10 Engagement groove 11 Engagement wall 12 Bottom face 20 Hill part 21 Outer peripheral wall 30 Driver bit 31 Engagement blade

Claims (4)

In a screw composed of a head (2) having a drive hole (4) and a leg (3) integral with the head (2), and a thread (5) formed on the leg,
A drive hole is formed in the center of the head from the head surface side to the leg, and a plurality of engagement grooves (10) are formed in the radial direction from the center of the drive hole, and adjacent to the engagement groove. Of the surface of the hill portion (20) formed between one engagement groove, the hill portion on the screwing rotation direction side is inclined toward the seat surface side so that the screwing rotation direction side becomes deeper (θ). Further, the head drive hole of the screw part is characterized in that the tilt direction is parallel to the center line of the engagement groove located on the screw loosening direction side of the hill.   The head has an outer peripheral wall (21) whose outer periphery of a hill portion located between radial ends of engaging grooves adjacent to each other becomes deeper as it moves in the screwing rotation direction. 2. The head drive hole for a screw part according to claim 1.   The engagement groove (11) engages with the engagement blade (31) of the driver bit (30) when tightening the screw, and the engagement wall (11) engages when the screw is loosened. The head drive hole for a screw part according to claim 1 or 2, wherein the height from 12) is increased.   The head drive hole for a screw component according to claim 1, 2 or 3, wherein the inclination angle (θ) is greater than 8 ° 32 'and less than 17 ° with respect to a plane perpendicular to the axis of the screw. .

Images