JP2007205482A - Drill screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill screw 1 capable of smoothly drilling a hole in a thick die steel B. <P>SOLUTION: The drill screw 1 is equipped with: a shank 2 having a screw part 3 with a screw thread 7 formed on the outer periphery; a drill part 4 positioned at the tip of the shank 2; and a head 5 positioned at the base end of the shank 2. A screwless part 6 is formed between the screw part 3 and the drill part 4. The nominal diameter of the screw part 3 is set to 6 mm or larger. The screw thread 7 of the screw part 3 is set to a fine pitch P, and composed of a tapered part 9 gradually becoming higher from the screwless part 6 toward the head 5, and a straight part 8 with a constant height continuing from the end of the tapered part 9. The outer diameter Dd of a barrel 17 is made smaller than the outer diameter Ds of the straight part 8 and larger than a root diameter Ds' of the straight part 8. The sum Lh of the axial lengths of the barrel 17 and the screwless part 6 is set the same as the sum of the thickness Ta+Tb of a workpiece A and die steel B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drill screw used to fasten a second member (workpiece) to a first member such as a mold steel having a thickness of 5.0 mm or more.

  2. Description of the Related Art Conventionally, drill screws having a drill portion at the tip of a shank (shaft) have been widely used to fasten a workpiece made of metal or wood based on a steel having a C-shaped cross section, for example.

  Patent Document 1 discloses an example of this type of drill screw. This drill screw is used to fasten a soft wooden workpiece to a hard steel plate. The drill has a thread formed on the outer periphery, a drill provided at the tip of the shank, and a shank. And a head provided at the base end of the. A narrow unthreaded portion is formed between the screw portion and the drill portion of the shank. In Patent Document 1, a type having a nominal diameter (the outer diameter of the screw portion) of 6.0 mm is cited as a specific example. The outer diameter of the unthreaded part is smaller than the outer diameter of the drill part.

In order to fasten a workpiece to a steel mold using such a drill screw, first press the workpiece while rotating the drill screw using an electric or pneumatic rotating tool with the workpiece superimposed on the surface of the steel mold. By applying, the drill portion is penetrated from the workpiece to the die steel, and then the screw portion is bitten into the inner wall of the through hole formed in the die steel.
JP-A-61-189310

  By the way, when constructing relatively thick metal structural materials as in the case of building a steel frame of a building, a pre-drilled hole is made in both structural materials in advance, and these structural materials are overlapped. In general, a construction method is adopted in which a bolt is inserted into the tip hole and a nut is screwed into the tip of the bolt and fastened. The reason for adopting such a construction method is to ensure the fastening strength in the axial direction of the bolt and the shear strength in the direction orthogonal to the axial center of the bolt.

  However, in the fastening with bolts and nuts, there is a problem that the construction cost increases because it takes time to align the front holes of the two structural members and to handle the bolts and nuts (screwing work etc.).

  In this regard, if the above-described drill screw can be used when fastening metal structural members, the structural member itself can be made to function as a nut, and the efficiency of fastening work can be improved. In this case, as the thickness of the structural material increases, an increase in the amount of chips to be eliminated and an increase in screwing torque become problems.

  However, the drill screw of Patent Document 1 is for fastening a soft material and a thin structural material to the end, and relates to the amount of chips, screwing torque, etc. when a hole is formed in a relatively thick structural material. Since it is a careless thing, it is understood that it cannot be used as it is for fastening structural members.

  Then, this invention makes it a technical subject to provide the drill screw which can be used also for the fastening of structural materials.

  In order to solve this technical problem, the invention of claim 1 is provided with a shank having a thread portion having a thread formed on the outer periphery, a drill portion provided at the tip of the shank, and a base end of the shank. A head portion, a threadless portion is formed between the thread portion and the drill portion of the shank, and the nominal diameter of the thread portion is set to 6.0 mm or more, A drill screw used for fastening a second member to a metal first member having a thickness of 5.0 mm or more, wherein the thread is adjacent to a follower flank across a valley. A tapered portion that is set to a fine pitch so that the base of the advance side flank matches or is close to each other, and the height gradually increases from the unthreaded portion toward the head, and the taper The height is constant at the end of the section On the other hand, the drill portion includes a barrel portion that extends concentrically with the shank, and a plurality of cutting blades that are formed at the tip of the barrel portion so as to be inclined with respect to the axis. And a plurality of longitudinal grooves for forming the cutting blade, and the base ends of the longitudinal grooves extend beyond the body part to the unthreaded part, and the body in the drill part The outer diameter of the portion is smaller than the outer diameter of the straight portion in the screw thread, and is set to be the same diameter or larger diameter as the valley diameter. The sum of the axial lengths of the body portion of the drill portion and the unthreaded portion of the shank is set to be equal to or greater than the sum of the thicknesses of the first member and the second member. Further, the axial length of the tapered portion in the thread is equal to or greater than the thickness of the first member. Is that is set to.

  According to a second aspect of the present invention, in the drill screw according to the first aspect, at least a tapered portion of the threaded portion has a notch formed by notching the screw thread inward in a radial direction so as to cross the thread thread. And a notch groove having a depth deeper than the bottom of the thread ridge extends in substantially the same direction as the axis, and the straight portion of the screw portion is The height of the screw thread is set to 0.5 mm or more and 1.0 mm or less, and the outer diameter of the unthreaded portion is 0.8 to 0.9 times the outer diameter of the trunk portion. It is set.

  In the drill screw of the present invention, first, the outer diameter of the thread portion is set to 6.0 mm or more, and the entire screw has high strength. And since the axial direction length of the trunk | drum in the said drill part is as long as more than the thickness of the metal 1st member which has the thickness of 5.0 mm or more, the frictional heat by screwing from the trunk | drum of the said drill part. Easy to escape outside. For this reason, when a hole is made in the first member, it is possible to significantly reduce the possibility that the shank will be damaged by screwing torque and break, or the drill portion may be seized and the cutting edge may be bent.

  Further, the thread pitch in the thread portion is set to a fine value such that the roots of the follower side flank and the advance side flank adjacent to each other across the valley match or are close to each other. Since the outer diameter of the front end portion is formed in a tapered shape with a very gentle angle, the screwing torque to the first member and the second member can be suppressed as much as possible.

  Particularly in this case, since the axial length of the tapered portion in the screw thread is set to be equal to or greater than the thickness of the first member, the screwing torque can be reduced even in the initial stage of tapping the screw thread on the first member. It does not increase rapidly.

  Further, since the sum of the axial lengths of the body portion of the drill portion and the unthreaded portion of the shank is set to be equal to or greater than the sum of the thicknesses of the first member and the second member, the drill portion is After passing through one member and the second member (after the cutting (drilling) of the first member is completed), the thread enters the second member. For this reason, even when the second member has not been previously drilled, the through hole of the second member is always open upward while the drill portion is screwed into the first member. Therefore, the chip discharge performance is good.

  As can be seen from the above, according to the drill screw of the present invention, a metal first member having a thickness of 5.0 mm or more can be smoothly drilled, and the drilled member itself can function as a nut. Can do. For this reason, since it is possible to fasten thick metal members by just screwing in the drill screw, the use (applicability) of the drill screw is dramatically increased, such as applying the drill screw to construction materials such as buildings. To do. Thereby, it can contribute to suppression of construction cost.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described with reference to the drawings (FIGS. 1 and 2). 1A is a front view of a drill screw, FIG. 1B is a sectional view taken along line Ib-Ib of FIG. 1A, FIG. 1C is a bottom view of the drill portion, and FIG. 2 is explanatory drawing which shows an example of a construction procedure.

(1). Configuration of Drill Screw As shown in FIG. 1, the drill screw 1 of the present embodiment is made of a metal wire material such as steel or stainless steel, and a threaded portion 3 (thread) is formed on the outer peripheral surface. The shank 2 is provided, a drill portion 4 provided at one end (tip) of the shank 2, and a head 5 provided at the other end (base end) of the shank 2. A narrow threadless portion 6 is formed between the screw portion 3 and the drill portion 4 in the shank 2.

  In the present embodiment, the overall length La of the drill screw 1 (the length from the tip of the drill portion 4 to the root of the screw portion 3) is 50.0 mm, the axial length Lb of the screw portion 3 is 32.0 mm, and the drill portion 4 The axial length Lc is set to 13.0 mm, and the axial length Ld of the unthreaded portion 6 is set to 5.0 mm.

  The thread portion 3 is formed with a single thread 7, and the pitch P of the thread 7 is such that the roots of the follower flank and the advance flank adjacent to each other across the valley coincide or are close to each other. It is set to a fine value.

  The thread 7 of the threaded portion 3 is continuous with the tapered portion 9 whose height (outer diameter) gradually increases from the unthreaded portion 6 toward the head 5 side, and the end of the tapered portion 9. The straight portion 8 has a constant height. In other words, the head 5 side of the screw thread 7 is a straight straight portion 8 along the axis, while the unthreaded portion 6 side has an outer diameter of several degrees or less with respect to the axis. The tapered portion 9 is tapered at the angle θ. In the present embodiment, the axial length Le of the straight portion 8 is set to 21.0 mm, and the axial length Lf of the tapered portion 9 is set to 11.0 mm.

  At least the tapered portion 9 of the screw thread 7 is formed with a notch 10 having a substantially V-shaped cross-section in which the screw thread 7 is notched radially inward so as to be aligned in the axial direction across the screw thread 7. . In the present embodiment, there are three rows of notches 10 aligned in the axial direction, and these rows of notches 10 are equally spaced along the circumferential direction of the tapered portion 9 (almost 120 ° in FIG. 1B). Is arranged. The row of notches 10 is inclined at a slight angle with respect to the axis, and extends over almost the entire length of the tapered portion 9.

  In addition, although each notch 10 of this embodiment is the depth which reaches the valley bottom of the screw thread 7, it is not restricted to this, You may dent deeply from the valley bottom of the screw thread 7, or you may make it shallow shallowly. . The row of notches 10 may extend long up to the straight portion 8, or conversely as short as the midway portion in the longitudinal direction of the tapered portion 9. The row of notches 10 may be one or a plurality of rows, and may extend in parallel with the axis.

  As shown in FIGS. 1A and 1C, the tapered portion 9 of the thread 7 in the thread portion 3 has a depth deeper than the valley bottom of the thread 7 between two adjacent notch 10 rows. One notch groove 11 having a substantially V-shaped cross section is formed. The cutout groove 11 extends in substantially the same direction (substantially parallel) as the axis, and includes a first vertically long surface 11a and a second vertically long surface 11b that intersect each other at substantially right angles. The vertical edge portion 11c of the first vertically long surface 11a located on the downstream side in the screwing direction can also function as a cutting blade for forming a female screw on the steel plate B described later.

  The drill portion 4 provided at the tip of the shank 2 includes a barrel portion 17 extending concentrically with the shank 2 and a plurality of cutting blades 13 formed at the tip of the barrel portion 17 so as to extend obliquely with respect to the axis. And a plurality of vertical grooves 12 for forming the cutting edge 13.

  The drill portion 4 of the present embodiment has two cutting blades 13 by forming longitudinal grooves 12 (two in total) at locations facing each other across the axis. The longitudinal grooves 12 are for releasing chips when cutting the steel plate B described later, and both of the longitudinal grooves 12 extend from the tip of the drill part 4 to the middle of the screwless part 6 beyond the body part 17. An axial length Lg of the body portion 17 in the present embodiment is 10.0 mm. The tips of both cutting edges 13 are connected via a chisel edge 13a. In addition, the cutting blade 13 and the vertical groove 12 are not limited to two, and may be three or more.

  In the present embodiment, the outer diameter Ds of the straight portion 8 corresponds to the nominal diameter of the screw portion 3, and its value is 8.0 mm. The valley diameter Ds ′ of the straight portion 8 is 6.5 mm. The height H of the thread 7 in the straight portion 8 is not less than 0.5 mm and not more than 1.0 mm. A specific height H dimension is 0.75 mm.

  The outer diameter Dd of the drill part 4 (body part 17) is set to 7.2 mm, which is smaller than the outer diameter Ds of the straight part 8 but larger than the valley diameter Ds ′. Of course, the outer diameter Dd of the trunk portion 17 may be the same as the valley diameter Ds ′ of the straight portion 8. The outer diameter Dn of the screwless portion 6 is 0.8 to 0.9 times larger than the outer diameter Dd of the body portion 17. The specific outside diameter Dn of the screwless portion 6 is 6.2 mm.

  On the other hand, the head 5 is formed in a hexagonal shape in plan view, and a hexagonal driver engagement hole 14 with which a driver bit (not shown) is engaged is formed on the top surface. The driver engagement hole 14 may be a cross-shaped (minus) shape, a star shape, a square shape, or the like.

  Further, a thin ring-shaped flange 15 is formed at the lower end of the head portion 5, and although not shown in detail, the seat surface of the head portion 5 faces downward to surround the root of the shank 2 (screw portion 3). An open circular recess is formed.

  The drill screw 1 is made of a metal round bar (or wire) as a raw material, first the head portion 5 is formed, then the drill portion 4 is formed, and then the screw portion 3, the unthreaded portion 6 and the notch 10 are rolled. After that, it is manufactured by a process of cutting or forging the notch groove 11 (processing such as quenching and plating is performed if necessary).

(2). Next, referring to FIG. 2, using the drill screw 1, the workpiece A made of a metal plate as the second member is turned into a steel plate B having a cross-sectional C shape or a hollow square shape as the first member. An example of the procedure for fastening will be described. In this case, the thickness Ta of the workpiece A is 9.0 mm, and the thickness Tb of the die steel B is 6.0 mm. The sum (15.0 mm) of these thicknesses is the axial direction of the body portion 17 and the unthreaded portion 6. The length is the same as the sum Lh (= Lg + Ld, see FIG. 1A). Needless to say, the axial length Lg (10.0 mm) of the body portion 17 is equal to or greater than the thickness Tb (6.0 mm) of the steel plate B.

  The sum of the thicknesses of the workpiece A and the steel plate B (Ta + Tb) may be slightly shorter than the sum Lh (= Lg + Ld) of the axial lengths of the body portion 17 and the unthreaded portion 6. The length Le in the axial direction of the straight portion 8 is a dimension equal to or greater than the sum of these thicknesses (Ta + Tb) in order to securely fasten the workpiece A and the steel plate B.

  First, as shown in FIG. 2A, the tip hole 16 is drilled in the workpiece A with a drill (not shown). The tip hole 16 is preferably large enough to fit the threaded portion 3 (straight-shaped portion 8) of the drill screw 1 but may have some backlash.

  Next, after the workpiece A is overlaid on the surface of the mold steel B, the drill screw 1 is inserted into the front hole 16 with the drill portion 4 first (see FIG. 2B), and a driver bit (not shown) The drill screw 1 is pressed against the steel mold B while rotating the drill screw 1 using a screw (see FIG. 2 (c)). Then, until the seat surface of the head 5 comes into contact with the surface of the workpiece A, the screw portion 3 (screw thread 7) is screwed in a state of being bitten into the inner wall of the through hole formed in the steel plate B (FIG. 2). (See (d)).

  In this case, the outer diameter Ds of the straight portion 8 corresponding to the nominal diameter of the screw portion 3 is set to 8.0 mm, and the outer diameter Dn of the unthreaded portion 6 is set to 0. 0 of the outer diameter Dd of the drill portion 4. Since the size is 8 to 0.9 times, the drill screw 1 as a whole has high strength. In addition, since the axial length Lg of the barrel portion 17 in the drill portion 4 is longer than the thickness Tb of the die steel B, the frictional heat due to screwing can easily escape from the barrel portion 17.

  For this reason, even if the steel plate B having a thickness of 6.0 mm is drilled, the unthreaded portion 6 having a narrower width than the other portion is damaged by the screwing torque and broken, or the drill portion 4 is seized and the cutting blade 13 is bent. There is almost no risk that the hole will be drilled smoothly. Note that the fact that the axial length Lg of the body portion 17 is longer than the thickness Tb of the die steel B also contributes to the straight running stability of the drill screw 1 during screwing.

  Further, since the outer diameter Dn of the unthreaded portion 6 is as small as 0.8 to 0.9 times the outer diameter Dd of the body portion 17, the unthreaded portion 6 becomes the leading hole 16 in the workpiece A in the course of screwing. There is no contact with the inner wall. In addition, the chips generated by screwing the drill part 4 into the steel plate B are sent upward in the two longitudinal grooves 12 and discharged to the outside from the front hole 16 or the inner wall of the front hole 16 and It accumulates in the gap between the unthreaded portion 6. For this reason, the possibility that the screwing torque increases due to the presence of chips can be suppressed, and the fastening operation can be performed smoothly.

  Further, the pitch P of the screw thread 7 in the screw part 3 is set to a fine value so that the roots of the follower side flank and the advance side flank adjacent to each other across the valley coincide or are close to each other. Since the outer diameter of the tip of the steel plate is formed in a tapered shape with a very gentle angle, the amount of bite per rotation when the female screw is formed on the steel plate B with the screw portion 3 is very small. The biting of the part 3 can be smoothly performed with low torque. And since the notch 10 and the notch groove 11 were formed in the thread part 3, the escape of a chip | tip becomes good and the approach of the thread part 3 with respect to the type steel B becomes smooth. As a result, screwing can be performed more easily.

  In this embodiment, since the sum (Ta + Tb) of the thicknesses of the workpiece A and the steel plate B is the same as the sum Lh (= Lg + Ld) of the axial lengths of the body portion 17 and the unthreaded portion 6, the cutting blade After the cutting (drilling) of the mold steel B by 13 is completed, the screw portion 3 enters the workpiece A. For this reason, even if the tip hole 16 has not been previously drilled in the workpiece A, while the drill portion 4 is screwed into the mold steel B, the through hole of the workpiece A is always maintained in an upwardly opened state, Therefore, even if the mold steel B having a thickness of 6.0 mm is drilled, the chip discharge performance is good and the risk of an increase in screwing torque can be reliably suppressed.

  On the other hand, the pitch P of the thread 7 is made fine to increase the number of threads, and the height H of the thread 7 in the straight portion 8 is set to 0.5 mm or more and 1.0 mm or less, so that the screwing torque is lowered. While maintaining it, a moderate hook allowance to the mold steel B can be maintained, and a necessary and sufficient fixing strength can be secured. In addition, there is an effect that it is difficult to loosen due to the large number of peaks.

  As is apparent from the above, according to the drill screw 1 of the present embodiment, the steel plate B having a thickness of 6.0 mm can be smoothly drilled, and the steel plate B itself to be drilled can function as a nut. it can. For this reason, since it is possible to fasten a thick metal member only by screwing in the drill screw 1, the use (applicability) of the drill screw 1, such as applying the drill screw 1 to the construction of a structural material such as a building, has jumped. Increase. Thereby, it can contribute to suppression of construction cost.

  By the way, for example, when the workpiece A is fastened to the mold steel B as a vertically extending support or when it is shaken by an earthquake, the drill screw passing through the workpiece A and the mold steel B is orthogonal to the axis. In this embodiment, the outer diameter Ds of the straight portion 8 corresponding to the nominal diameter of the drill screw 1 is set to 8.0 mm, which is larger than the conventional product. In addition, it has a high shear strength that can withstand the shearing force described above.

  In addition, since the thread 7 of the threaded portion 3 bites into the mold steel B in the fastened state and only the workpiece A can be displaced with respect to the drill screw 1, the shear force acting on the drill screw by this displacement movement is It will be kept small.

  Therefore, the work A can be stably fixed to the steel plate B with a small number without increasing the number of fastening screws 1. Further, since the number of fastenings can be reduced, the efficiency of fastening work can be improved and the construction cost can be reduced.

(3). Others The present invention is not limited to the above-described embodiment, and can be embodied in various forms. For example, the thickness Tb of the steel plate B as the first member may be 5.0 mm or more, but is preferably 5.0 mm or more and 12.0 mm or less. The second member is not limited to metal but may be a wood board such as plywood. Further, it is not always necessary to open the leading hole 16 for the second member.

  In the above-described embodiment, the nominal diameter of the screw portion 3 (the outer diameter Ds of the straight portion 8) is set to 8.0 mm, but it is sufficient that it is at least 6.0 mm or more. And according to the outer diameter Ds dimension of this straight-shaped part 8, the outer diameter Dd etc. of the drill part 4 should just be set. In addition, the configuration of each unit is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention.

It is explanatory drawing of the drill screw in this embodiment, (a) is a front view, (b) is Ib-Ib sectional drawing of (a), (c) is a bottom view of a drill part, (d) is a head FIG. It is explanatory drawing which shows an example of a construction procedure.

Explanation of symbols

A Workpiece B as second member Die steel Dd as first member Outer diameter Dn of drill part Outer diameter Ds of unthreaded part Ds Outer diameter of straight part 1 Drill screw 2 Shank 3 Screw part 4 Drill part 5 Head part 6 Screw None part 7 Thread 8 Straight part 9 Tapered part 12 Vertical groove 13 Cutting edge 13a Chisel edge 17 Body

Claims (2)

A shank having a thread portion with a thread formed on the outer periphery, a drill portion provided at the tip of the shank, and a head portion provided at the base end of the shank, and the thread portion of the shank; An unthreaded portion is formed between the drill portion, the nominal diameter of the thread portion is set to 6.0 mm or more, and the first member made of metal having a thickness of 5.0 mm or more A drill screw used to fasten the second member,
The screw thread is set to a fine pitch so that the roots of the follower side flank and the advance side flank adjacent to each other across the valley coincide or approach each other, and from the unthreaded portion to the head side. On the other hand, it is composed of a tapered portion whose height gradually increases toward the end and a straight portion having a constant height continuously to the end of the tapered portion,
The drill portion includes a barrel portion that extends concentrically with the shank, a plurality of cutting blades that are formed at the tip of the barrel portion so as to be inclined with respect to an axis, and the cutting blade. A plurality of longitudinal grooves, and the base ends of these longitudinal grooves extend beyond the body portion to the unthreaded portion,
The outer diameter of the barrel portion in the drill portion is smaller than the outer diameter of the straight portion in the screw thread, and is set to be the same diameter or larger than the valley diameter. The direction length is equal to or greater than the thickness of the first member, and the sum of the axial lengths of the body portion of the drill portion and the unthreaded portion of the shank is the thickness of the first member and the second member. The axial length of the tapered portion in the thread is set to be equal to or greater than the thickness of the first member,
Drill screw. At least the tapered portion of the thread is formed with a notch formed by notching the thread inward in a radial direction so as to be aligned in the axial direction across the thread, and from the root of the thread The notch groove with a deep depth is formed to extend in substantially the same direction as the axis,
The straight portion of the screw portion has a height of the thread set to 0.5 mm to 1.0 mm,
Furthermore, the outer diameter of the threadless part is set to a size of 0.8 to 0.9 times the outer diameter of the body part,
The drill screw according to claim 1.

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