JP2012092889A - Drive screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a return stop function while improving workability in fastening.SOLUTION: The drive screw includes: a guide 3 provided at a distal end of a shaft part 2; a first screw 4 provided at a base end of the guide and including a plurality of screw threads 6; a second screw 5 provided at the base end of the first screw and having a screw shape equivalent to that of the first screw; and a head 1 provided at the base end of the shaft part 1. The screw threads 6, 7 of the first and second screws 4, 5 are formed by shifting the phases by a half pitch.

Description

  The present invention relates to a driving screw.

  As a screw for attaching a member to be fastened to a mating member made of a soft metal material having low toughness, for example, aluminum, a driving screw that can be fixed by one behavior is used.

  A conventionally known driving screw is disclosed in Patent Document 1. In this conventional driving screw, a plurality of threads b having a large lead angle θ are formed in the shaft portion a so as to show the front schematically shown in FIG. 11 and the EE cross-sectional enlarged section of FIG. Therefore, this is driven into the pilot hole e drilled in the mating member c and the fastened member d by means of hitting with a hammer, press-fitting with a pressing device, or the like.

  Further, in order to improve workability at the time of driving, the lead angle θ of the screw thread b is formed to be large and can be driven with a small load.

  However, according to the driving screw described above, since it can be driven with a small force when driven, even if workability is good, it is easy to turn in the reverse direction when vibration is applied after fastening, and the seat of the head f of the driving screw. There is a problem that the surface is lifted from the surface of the fastened member d, the fixing function is lost, and the surface is finally removed.

  On the other hand, there is a screw described in Patent Document 2 in consideration of the above points. The one disclosed in this document is composed of a main screw h formed from the tip of the screw shaft g and an auxiliary screw i in the reverse direction provided below the head f as shown in FIG. By screwing h and then turning the auxiliary screw i in the opposite direction and screwing in, the rotation directions of the screws h and i do not loosen, and the detent is prevented.

  However, according to this, since the main screw h is once screwed and then rotated in the reverse direction and the auxiliary screw i is screwed in, the mating member c causes a large plastic flow. However, there is a drawback that the workability is inferior, for example, the rotational resistance of the screw is remarkably large and the female screw is broken.

Japanese Utility Model Publication No. 55-7407 JP 2002-349528 A

  In view of this, it is an object of the present invention to provide a driving screw that can exert a large detent function without impairing workability during fastening.

  As means for solving the above-mentioned problems, the present invention provides a guide portion provided at the distal end of the shaft portion, a first screw portion provided on the proximal end side of the guide portion and having a plurality of threads, and the first screw. A second screw portion having a screw shape equivalent to the first screw portion, and a head portion provided at the base end of the shaft portion, the first screw portion and the second screw This is because the screw thread with the part is formed by shifting the half pitch phase.

  The lead angle of the thread of the first and second threaded portions is preferably in the range of 60 ° to 80 °, more preferably 70 ° to or around that. The number of threads is about 4 to 8.

  It is preferable that at least one screw thread of the first and second screw portions is tapered so that the base end side is high and gradually decreases toward the tip.

  A screwless part can be provided between the second screw part and the head part.

  Moreover, it is preferable to form a longitudinal groove in the peak part of the thread of the said 1st, 2nd thread part.

  Furthermore, an interval portion having a required width may be provided between the base end of the first screw portion and the tip end of the second screw portion.

  The head can be formed with a driver engagement groove that is rotated and removed by a screwdriver.

  According to the present invention, at the initial stage of driving, the guide portion at the tip of the shaft portion guides and enters the member to be fastened, and when reaching the first screw portion, the guide portion is guided by the lead angle of the screw thread while forming a groove. Further, when reaching the second threaded portion, the threaded portion of the second threaded portion formed by shifting by a half pitch from the threaded portion enters the flange between the grooves formed by the threaded portion of the first threaded portion. As a result, the flange portion is collapsed to the left and right sides, and a groove having a phase different from that of the groove formed by the first screw portion is formed. Therefore, the first screw portion tries to move in the removal direction. However, since the self-formed groove is already crushed by the thread of the second thread, it cannot be rotated in the return direction, and the return rotation is completely prevented and the function of the driving screw is completed. Can do.

  By increasing the lead angle of the screw thread to 60 ° to 80 °, there is less resistance at the time of driving, and workability is improved. Therefore, it is possible to reliably prevent return direction rotation while achieving improvement in workability. The effects of two contradictory aspects of being able to do so can be obtained at once.

  If the taper is attached to the virtual outer periphery of the threaded portion so that the threaded portion of the first threaded portion and / or the second threaded portion becomes higher as the base end side is higher and reaches the distal end, the resistance at the time of driving can be further reduced. Workability can be further improved.

  If a groove at the top (peak) of the screw thread of the square screw part is formed, a guide function at the time of driving can be achieved and smoother driving can be performed.

1 is a schematic front view of an embodiment of a driving screw according to the present invention. FIG. The simplified front view of a modification. The simplified front view of another modification. The expanded sectional view of a screw thread. The perspective view which expands and shows typically the principal part of the driving screw of FIG. The perspective view which expands and shows typically the principal part of the driving screw of FIG. (A)-(D) is sectional drawing which expands and shows each surface of the AA of FIG. 1, FIG. 2, BB, CC, DD cross section. The partial perspective view which shows the modification of a screw thread. Same as above, front view. Explanatory drawing which shows typically the state at the time of driving of the driving screw by this invention. The schematic front view of a conventional product (patent document 1). EE arrow sectional drawing of FIG. The front view of other conventional products (patent documents 2). FIG. 12 is a graph showing the unloading load of the conventional product shown in FIG. 11. The graph which shows the unloading load of this invention product.

  FIG. 1 shows an embodiment of a driving screw according to the present invention, which has a cylindrical guide portion 3 at the distal end of a shaft portion 2 having a head portion 1 at the proximal end, and on the proximal end side of the guide portion 3. A first screw portion 4 provided and a second screw portion 5 provided on the proximal end side of the first screw portion 4 are provided, and the first and second screw portions 4 and 5 have a plurality of large lead angles θ. Thread threads 6 and 7 are formed. The number of threads is in the range of 4-8.

As shown in FIG. 4, when the angles formed by the perpendicular line and the flank angle formed from the peak of each thread 6 and 7 to the axis are α ₁ and α ₂ , respectively, Flank angle α ₁ on the part side) is 30 ° to 40 °, flank angle α ₂ on the opposite side (play side) is 30 ° to 40 °, and angle α ₁ + α _{2 of the} threads 6 and 7 is 60 ° to 80 °. It is preferable to set it at °, more preferably 70 °.

  In the driving screw shown in FIG. 1, as shown in FIG. 5, the screw threads 6 and 7 of the first and second screw portions 4 and 5 have the same height from the base end side to the tip end side. , 7 has a cylindrical outer peripheral shape.

  In the driving screw of the form shown in FIG. 2, as shown in FIG. 6, the angular threads 8 and 9 of the first screw portion 4 and the second screw portion 5 are gradually increased from the base end 8a, 9a side to the tip end 8b, 9b side. The hypothetical outer peripheral shape formed by these screw threads 8 and 9 is tapered so as to reduce the resistance during driving and improve workability. Has been made.

  In addition, the taper-shaped screw thread inclines only the screw thread 8 of the first screw part 4 on the tip side, and the screw thread 9 of the second screw part 5 is driven straight to reduce the initial resistance and reduce the driving resistance. You may make it make it. Conversely, only the thread 9 of the second screw portion 5 may be inclined.

  In FIG. 3, a screwless portion 10 is formed between the first screw portion 4 and the second screw portion 5, and a paragraph is given when the driving shifts from the first screw portion 4 to the second screw portion 5. A smooth transition to the threaded portion 5 is achieved.

  8 and 9 show other forms of the threads 6 and 7 of the first screw part 4 and the second screw part 5, and the screw threads 11 and 12 in this form have the longitudinal grooves 13 and 12 at the ridges. 14 is formed so that the transition from the first screw portion 4 to the second screw portion 5 is smooth, the contact area with the counterpart member c is increased, the biting is improved, and the detent effect is further enhanced. Has been made.

  The longitudinal grooves 13 and 14 may be provided only in the thread 12 of the first screw portion 4.

  A driver engaging groove 1a is formed on the top of the head 1 to engage the driver when the driving screw is removed.

  Next, the operation of the driving screw shown in FIG. 1 will be described.

  At the time of driving, the guide portion 3 at the tip is inserted into the pilot hole e of the mating member a through the fastened member d, and the head 1 is pressed and pressed by a pressing device (or tapping). When entering the second threaded portion 5 while being guided by the lead angle θ of the thread 6 and further reaching the second threaded portion 5, the thread 6 of the first threaded portion 4 is engraved as shown schematically in FIG. When the thread 7 of the second screw part 5 having a half-pitch phase different from that of the thread 6 enters the flange j between the grooves, the previous flange j is indicated by an arrow k. As shown in the figure, it is deformed to fill the groove by breaking left and right, and by this action, the screw groove formed by the second screw portion 5 is buried in the screw groove formed by the first screw portion 4, thereby firmly This results in a biting, and the rotation in the pulling-out direction is combined in an impossible state.

  As shown in FIGS. 2 and 3, if the threads 8 and 9 of the first and second screw portions 4 and 5 are tapered, the resistance during driving is reduced and workability during driving is improved. To do.

  Next, Table 1 and FIGS. 14 and 15 show the test results of the unloading load between the conventional driving screw shown in FIG. 11 (disclosed in Patent Document 1 and hereinafter referred to as a conventional product) and the present invention product. Show.

[Test conditions]
Driving screw size 2 mm
Mating member: Aluminum (A5056)
Measurement item ... About the unloading force of the driving screw driven into the pilot hole of soft metal material
Measure. For this unloading load, drive from the bottom of the pilot hole.
Insert a pin slightly thinner than the
By measuring the stroke and load (missing load value).
Measuring device: Shimadzu Corporation Universal testing machine (UH300) is used. Push in
The moving amount in the removal direction is 10 mm / min.

  As can be seen from Table 1, the product according to the present invention has an unloading load of about 20% larger than that of the conventional product, and it has been found that it is difficult to loosen.

  As can be seen from the results of the drop-out load test shown in FIGS. 14 and 15, the greatest effect is that when the load is applied in the pulling direction, there is a situation where it is opposed by a certain load, and it is difficult to return. .

That is, FIG. 14 shows the relationship between the unloading load and the stroke of the conventional product shown in FIG. 11, and FIG. 15 shows the relationship between the unloading load and the stroke of the product of the present invention shown in FIG. It has been found that the resistance decreases immediately after the release load is applied to the product, whereas the product of the present invention resists tenaciously even if the release load is continued.

DESCRIPTION OF SYMBOLS 1 Head part 2 Shaft part 3 Guide part 4 1st thread part 5 2nd thread part 6,7,8,9,11,12 Thread 10 Unthreaded part 13,14 Vertical groove (theta) Lead angle c Opposing member d Fastened Element

Claims (7)

  A guide portion provided at a distal end of the shaft portion; a first screw portion provided on a proximal end side of the guide portion and having a plurality of threads; and the first screw provided on a proximal end side of the first screw portion. A second screw portion having a screw shape equivalent to the portion and a head portion provided at the base end of the shaft portion, and the threads of the first screw portion and the second screw portion are formed by shifting a half pitch phase. A drive screw characterized by   2. The driving screw according to claim 1, wherein a lead angle of a thread of the first and second screw portions is in a range of 60 ° to 80 °.   3. The driving screw according to claim 1, wherein at least one screw thread of the first and second screw portions has a tapered shape that is high on the base end side and gradually decreases toward the tip end.   The driving screw according to any one of claims 1 to 3, further comprising a screwless portion between the second screw portion and the head portion.   The driving screw according to any one of claims 1 to 4, wherein a longitudinal groove is formed in a ridge portion of a thread of the first and second screw portions.   The driving screw according to any one of claims 1 to 5, wherein an interval portion having a required width is provided between a base end of the first screw portion and a tip end of the second screw portion.   The driving screw according to any one of claims 1 to 6, wherein a driver engaging groove is formed in a top of the head.

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