JP4684169B2 - Drill screw for wood - Google Patents

Description

  The present invention is a drill screw (hereinafter referred to as a drill screw) used when a metal workpiece is fastened to a wooden member (base material), for example, when a metal fitting for reinforcement or connection is fastened to a wooden structure material of a wooden house. In the description of FIG. 2, it may be simply referred to as “screw”. Here, examples of the wood-based member include a wooden square member, a plate member, and a particle board.

  In a wooden house, a metal member is fastened to a wooden member (mainly a structural material) such as a pillar, a beam, a trunk, a joist, and a rafter for reinforcement and connection. Moreover, fastening wooden members is also performed. Conventionally, a self-tapping type screw called a coach screw (coach screw) or a lag screw has been used as a means for fastening these metal fittings or wood structure materials.

  Coach screws and lag screws have larger outer diameters than normal wood screws (for example, nominal diameters of 8 to 12 mm), and the head is often hexagonal or hexagonal so that a large torque can be applied. In addition, the shaft has an unthreaded portion continuous with the head portion. In general, the tip end of the shaft of the coach screw and lag screw is tapered.For example, when fastening a metal fitting to a wooden member, a hole is made in advance in the wooden member with an electric drill, and Coach screw or lag screw is screwed in.

However, it is troublesome to make the pilot holes one by one in the wooden member, and there is a possibility that the positions of the prepared pilot holes and the mounting holes of the metal parts are shifted, and the metal parts cannot be fastened. As a countermeasure against this point, Patent Document 1 describes that a drill portion is formed on a coach screw to provide self-piercing properties.
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  For example, when fastening a metal fitting to a wooden member, it is possible to ensure that the necessary fastening strength can be ensured, that the deviation of the metal fitting does not occur at all or that the screwing resistance (torque) is as small as possible, and that the wooden member is not cracked. Moreover, it is necessary to satisfy, and as an important condition when used for fastening wooden structural materials of buildings, it is not easy to break when the structural materials tend to slide relative to each other due to earthquakes etc. It is required to have toughness (high shear strength).

  This invention makes it a subject to provide the drill screw which improved the quality, following the patent document 1 that the screw can be screwed into the wood-based member without a pilot hole.

A drill screw according to the present invention includes a shaft having a circular cross section and a head portion provided at a base end thereof, and a tip portion of the shaft is formed in a drill portion having a cutting edge, and the shaft has a rotation thereof. and threaded portion having 1 Article thread bites into the wood member is formed by, and is used to conclude the metallic workpiece made in wood member. And it is characterized by material, structure, heat treatment / hardness.

  That is, first, the material is made of one of carbon steel, chromium molybdenum steel, chromium steel, molybdenum steel, and non-tempered steel. Non-tempered steel is steel that has not been subjected to quenching and tempering heat treatment, and is generally a carbon steel type that has vanadium carbide precipitated in a mixed phase of pearlite phase and ferrite phase to enhance the strength. Is frequently used. Therefore, in a broad sense, it can be said that the majority falls within the category of carbon steel.

  Next, regarding the structure (shape and dimensions), a. A boss portion that fits into a tip hole that is previously vacated in the work is formed in a lower neck portion that is continuous with the head portion of the shaft, and is the outer diameter of the boss portion equal to the outer diameter of the thread? Or larger dimensions, b. A threadless portion having a diameter larger than the root diameter of the screw portion and smaller than the outer diameter is formed between the screw portion and the boss portion of the shaft; c. The vertical cross-sectional view of the thread is substantially triangular, the angle of the thread is 30 to 50 degrees, and the pitch is 1.5 to 2.5 times the width of the virtual bottom of the thread in the vertical cross-sectional view. It is characterized by three elements.

Furthermore, the heat treatment is not quenched, so that the core and the surface have the same hardness except for work hardening. And the hardness of a core part and a surface part is set to the range of Hv250-350. While to set the hardness Hv250~350 is to secure the toughness, and a means for holding the hardness, we use material having a hardness in this range, Ru can reduce the labor of working for this .

  As described in claim 2, a suitable angle of the thread crest is 40 to 50 degrees, and the height of the crest is slightly larger than or equal to the width dimension of the virtual base. Preferably it is set.

  The form of the head is mainly determined by the form of the workpiece. In claim 3, a hexagonal head with a flange and a disk-shaped flat head are listed. Of course, it is also possible to form a simple hexagon head or a socket type circular head. As described in claim 4, it is preferable that the boss portion and the unthreaded portion are continuous through a tapered portion having a taper.

  The drill screw according to the present invention is made of one of carbon steel, chrome molybdenum steel, chrome steel, molybdenum steel, and non-tempered steel, but these materials are cheaper than, for example, stainless steel, and Also, it has excellent workability and toughness.

  By the way, in the conventional coach screw or lag screw, the unthreaded portion and the head constituting the shaft are connected, and the unthreaded portion is a dimension between the root diameter and the outer diameter (the outer diameter of the thread) of the screw. However, the tip hole (mounting hole) that is pre-opened in the workpiece such as metal fittings is naturally larger in diameter than the outer diameter of the screw part because the screw part needs to be inserted. Because of this, there is a certain gap between the unthreaded part of the shaft and the inner periphery of the tip hole in the workpiece, and as a result, if there is even a slight looseness in the screw, there will be rattling between the workpiece and the screw. There is a problem that the work and the wood-based member are displaced when they are generated or when an external force is applied to the work or the wood-based member.

  On the other hand, in the present invention, there is a boss that is equal to or larger than the outer diameter of the screw thread in the lower part of the neck of the shaft, and this boss part fits into the tip hole of the workpiece. The gap between the inner periphery of the hole and the shaft can be remarkably reduced (theoretically, it can be made zero), and therefore, play and deviation of the work can be prevented or significantly suppressed.

  The reason why the screwless part is present in the conventional coach screw and lag screw is to increase the resistance to bending and shearing by causing the screwless part to bite into the wooden member, but also in the present invention. Since there is no screw portion, the same effect as the conventional one can be obtained.

Angle of the thread of a conventional coach screw or lag screw is turned 60 degrees, therefore, the pile of the cross-sectional shape is in a regular triangle, the height in order to improve the caught thread for wooden member When the height is increased, the cross-sectional area of the screw thread increases, and as a result, the screwing resistance (torque) increases, and cracks tend to occur and the burden on the operator is large.

  On the other hand, since the present invention has an angle of 30 to 50 degrees, the height of the mountain can be increased without increasing the cross-sectional area, and as a result, while ensuring high fastening strength, By reducing the screwing resistance, it is possible to prevent cracking and reduce the burden on the operator. As described in claim 2, it is more preferable that the angle of the thread is set to 40 to 50 degrees.

  If the thread height is too low, the pull-out resistance is reduced (in other words, the fastening strength is reduced). Conversely, if the thread height is too high, the screwing resistance is increased. In this regard, if the height of the ridge is set to be slightly larger than or equal to the width of the virtual base as in claim 2, it is preferable that the catch of the thread and the screwing resistance are balanced. It was.

  If the pitch of the thread is too small, the catching resistance with the wooden member will decrease and the fastening strength will decrease. Conversely, if the pitch is too large, the amount of penetration per one rotation with respect to the wooden member will increase and the screwing resistance will decrease. Increase. In this regard, as in the present invention, by setting the pitch to 1.5 to 2.5 times the width dimension of the virtual bottom of the screw thread in the longitudinal sectional view, the necessary fastening without excessively increasing the screwing resistance. Strength can be secured.

  In steel screws, the hardness and brittleness are inversely proportional to each other, and when the hardness is increased to, for example, Hv400 or higher after quenching (and tempering), a phenomenon of cracking easily occurs when shearing force or bending force is applied. Become. In the case of a structural material such as a column or beam in a building, it is important that the screw does not break even if it is bent by an external force.

  In this respect, since the screw of the present invention has a hardness of Hv 250 to 350 and is rich in toughness, it is not easily broken by shearing force or bending force, and separation between members can be prevented as much as possible. For this reason, it is suitable as a screw for wooden structural materials. Moreover, since the drill screw of the present invention is intended to be screwed into a wood-based member and the drill portion does not require high hardness as in the case of steel materials, there is a problem in cutting performance even with Hv 250 to 350. It does not occur. Therefore, it is possible to prevent or remarkably suppress breakage due to shearing force and bending force while ensuring cutting performance (perforation performance).

  In the screwing process of the screw, the unthreaded part of the shaft enters the front hole of the work, and then the boss part enters the front hole of the work and is finally tightened. Even if the lead hole core and the shaft core in the workpiece are misaligned, there is an advantage that the posture of the workpiece is automatically positioned by the guide action of the taper part (the inner diameter of the tip hole in the work and the boss part in the shaft (Even when the outer diameter is almost the same, the workpiece can be positioned automatically, so it is possible to accurately prevent the workpiece from rattling or shifting.)

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a structure of a drill screw, and FIGS. 2 and 3 are views showing a use state. First, the structure of the drill screw will be described with reference to FIG.

(1). Structure of drill screw In Fig. 1, (A) is a front view of a hexagonal head type drill screw, (C) is a front view of a flat head type drill screw, (B) is a plan view of (A), (D ) Is a plan view of (C), and (E) is a partial sectional view common to both types of screws.

  The hexagonal head type drill screw shown to (A) and (B) is equipped with the axis | shaft 1 and the hexagonal head 2 provided in the base end, and the flange 2a is formed in the head 2. FIG. A drill portion 3 having two cutting edges 3a and two longitudinal grooves 3b is formed at the tip of the shaft 1. Although the drill part 3 of this embodiment is provided with a chisel edge and the drill angle is about 120 degrees, it is also possible to make the drill angle small or to use a pinpoint method without a chisel edge.

  The shaft 1 is formed with a screw portion 5 having a single thread 4 starting from the terminal end of the drill portion 3, and between the screw portion 5 and the head 2 of the shaft 1, The unthreaded portion 6 is continuous with the screw portion 5 and the boss portion 7 is continuous with the head portion 2, and the unthreaded portion 6 and the boss portion 7 are continuous via a tapered portion 8 that is tapered. .

  The root diameter D1 of the screw portion 5 is slightly smaller than the outer diameter of the drill portion 3, and the outer diameter D2 of the unthreaded portion 6 is larger than the valley diameter D1 of the screw portion 5 and is the screw portion 5 (or screw). The diameter is set smaller than the outer diameter D3 of the mountain 4). In the present embodiment, the outer diameter D4 of the boss portion 7 is substantially the same as the outer diameter D3 of the screw portion 5. The axial length of the boss 7 is smaller than the thickness of the metal fitting 12 shown as an example of the workpiece in FIG. The length in the axial direction of the unthreaded portion 6 can be arbitrarily set according to the application.

  The thread 4 is a triangular triangular screw in a longitudinal sectional view, and the angle θ of the thread is set to about 45 degrees. Further, the height H of the mountain is set to be approximately the same as the width L of the virtual base 9 of the screw thread 4 in the longitudinal sectional view. The pitch P of the thread 4 is set to about twice the width dimension L of the virtual base 9. Therefore, a valley surface having a width dimension substantially the same as the width dimension L of the virtual bottom side 9 of the mountain is exposed in the threaded portion 5 in a strip shape.

  The expression of the width dimension of the imaginary base 9 of the thread 4 can be rephrased as the maximum axial thickness of the thread 4, the distance between adjacent valleys, or the flank of the follower flank and the advancing flank. In other words, it can be paraphrased as the distance from the hem. Looking at the pitch P in relation to the outer diameter D3 of the threaded portion, in this embodiment, the pitch P is about 1 / 3.5 of the outer diameter D3, and in relation to the valley diameter D1, the pitch P is P is about half of the valley diameter D1. In view of the ratio of the pitch P to the outer diameter D3 of the screw, in the present invention, the pitch P is preferably about 1/3 to 1/4 of the outer diameter D3.

  (C) The flat head type drill screw shown in (D) is basically the same as the hexagon head type drill screw. The difference from the hexagon head type drill screw is that the head 2 is formed in a thin disk shape. They are only a point where the hexagonal hole 10 is formed on the top surface as the engagement means of the driver bit, and that the length in the axial direction of the unthreaded portion 6 and the boss portion 7 is long.

  The drill screw of this embodiment is manufactured using a carbon steel wire such as a carbon steel wire for cold heading as a raw material. The manufacturing process is basically the same as in the past, and the shape is obtained through the process of processing the head 2 and the boss 7 by the header, processing the drill 3 by forging or cutting, and processing the thread 4 using a die. Finally, surface treatment such as plating is performed for rust prevention.

  Since the material is not hardened, the hardness basically maintains the hardness of the material, and the overall hardness is the same from the surface to the core. is there.). In addition, since the surface treatment for rust prevention is generally given to the screw, it is possible to heat when the rust prevention film is provided by baking, but the heating action in this case can be said to be a heat treatment that affects the hardness. Absent.

(2). Usage example Fig. 2 shows a usage example of a hexagon head type drill screw. In this example, for example, a wooden member 13 such as a pillar or beam for a wooden house is used to reinforce or connect with a steel plate fitting 12.

  The metal fitting 12 has a tip hole (attachment hole) 14 in advance, and the inner diameter of the tip hole 14 is slightly larger than the outer diameter D3 of the screw portion 5 and the outer diameter D4 of the boss portion 7. (In other words, the outer diameter D3 of the screw portion 5 and the outer diameter D4 of the boss portion 7 in the drill screw are slightly smaller than the inner diameter of the tip hole 14).

  The wooden member 13 does not need to have a pilot hole. The metal member 12 may be overlapped with the wooden member 13 and the shaft 1 of the drill screw may enter the wooden member 13 through the tip hole 14. In the initial stage of entry, only the drill part 3 enters the wooden member 13, and then when the thread 4 is applied to the wooden member 13, the cutting by the drill part 3 and the entry of the thread 4 are performed simultaneously. It enters the wooden member 13 by one pitch P per one rotation.

  And the boss | hub part 7 fits in the front hole 14 of the metal fitting 12, and the head 2 closely_contact | adheres to the surface of the metal fitting 12, This complete | finishes fastening. Although not shown in the drawings, the female screw groove formed by the entry of the screw thread 4 remains in the portion of the wooden member 13 where the screwless portion 6 has entered, and the screwless portion 6 has the female screw groove. As a result, the screw member 6 is forcibly inserted into the wooden member 13 so that the screwless portion 6 is fitted into the wooden member 13 tightly.

  In this screwing process, the screw thread 4 has a thread angle θ of 45 degrees and is smaller than the conventional angle (60 degrees), and the pitch P is not excessively small, thereby reducing the torque required for screwing. In addition, cracking of the wooden member 13 can be suppressed. The applicant of the present application measured the screwing torque for a comparatively-similar coach screw (with a pilot hole in the wooden member 13 in advance) and the present invention product. Has been confirmed to be suppressed to about 80%.

  Also, a screw is driven into the wooden member 13 on which the steel plate with the front hole is overlapped, and the screw is forcibly rotated with the seating surface of the head overlapping the steel plate. A test was conducted to determine if the screw was broken and the screw was idle, and it was confirmed that the product of the present invention had a strength about 1.6 times that of the conventional product. Further, the shear strength and pull-out resistance strength were equivalent to those of the conventional product.

  FIG. 3 shows an example of using a flat head type drill screw. In the example shown in FIG. 5A, the metal fitting 12 has a protruding portion (rib) 12a that protrudes outward, and a leading hole 14 is formed in the protruding portion 12a. In the example shown in (B), a thick steel member (for example, a H-shaped steel thick steel plate) 15 is used to fasten the wooden member 13. Furthermore, in the example shown to (C), it uses for fastening the plate-shaped metal fitting 12 and the panel 16 to the wooden member 13 together.

  By the way, as described above, the head 2 and the boss 7 are processed by forging using a header. However, due to the problem of the durability of the mold, the connecting portion between the boss 7 and the head seating surface has a fillet. When the boss 7 is fitted in the front hole of the work, the excessive part of the front hole of the work is held by the roundness of the screw. Can lead to incomplete problems. This problem can be dealt with by forming an annular recess 17 that is continuous with the outer periphery of the boss 7 in the seating surface of the head 2 as shown in FIG.

  That is, when the annular recess 17 is formed as shown in FIG. 4, even if the cross-sectional shape of the bottom of the annular recess 17 is rounded, the portion of the boss 7 exposed from the seating surface of the head 2 is completely straight. Therefore, even if the boss portion 7 is tightly fitted to the front hole 14 of the workpiece 12, the seating surface of the head portion 2 can be attached to the workpiece 12 without impairing the ease of processing of the head portion 2 and the boss portion 7. It can be closely attached to. Needless to say, forming the annular recess 17 in the seating surface of the head 2 and the screw of the type shown in FIGS. 1C and 1D are also applicable.

(3). Others The present invention can be embodied in addition to the above embodiments. For example, the shape of the head and the shape (or length) of the drill portion can be arbitrarily changed according to the application and the material of the counterpart material. It is also possible to form a round bar-shaped unthreaded portion between the drill portion and the screw portion, or conversely, to position the starting end of the thread on the drill portion.

It is a figure which shows the structure of a drill screw. It is a figure which shows the example of the use of a drill screw. It is a figure which shows the example of the use of a drill screw. It is a figure which shows a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 axis | shaft 2 head 3 drill part 4 thread 5 thread part 6 unthreaded part 7 boss part 8 taper part 9 virtual bottom of thread 12 metal fitting as an example of workpiece 13 wooden member as an example of wood system member

Claims (4)

A shaft having a circular cross section and a head portion provided at the base end thereof are provided, and a tip end portion of the shaft is formed in a drill portion having a cutting edge, and the shaft bites into a wooden member 1 by rotation thereof. threaded portion having a strip of threads and is formed, a drill screw which is used to conclude the metallic workpiece made in wood member,
a: The material is carbon steel, chromium molybdenum steel, chromium steel, molybdenum steel, has become from one of the non-heat treated steel,
b: The structure is
b1 . A boss part that fits into a tip hole that is previously vacated in the work is formed in the lower part of the neck that is continuous with the head of the shaft, and the outer diameter of the boss part is equal to the outer diameter of the thread or It has become a large size,
b2 . Between the boss portion and the threaded portion of the shaft, than the outer diameter a larger diameter than the root diameter of the threaded portion without the small diameter of the threaded portion is formed,
b3 . The vertical cross-sectional view of the thread is substantially triangular, the angle of the thread is 30 to 50 degrees, and the pitch is 1.5 to 2.5 times the width of the virtual bottom of the thread in the vertical cross-sectional view. It is a configuration that
c: The heat treatment and the hardness are not quenched, so that the core and the surface have the same hardness except for work hardening, and the hardness of the core and the surface is in the range of Hv 250 to 350. Set ,
Drill screw for wood. The angle of the thread ridge is 40 to 50 degrees, and the height of the ridge is set to be slightly larger than or equal to the width of the virtual base.
The wood material drill screw according to claim 1. The head is a hexagonal head with a flange or a disc-shaped flat head,
The wood material drill screw according to claim 1 or 2. The boss part and the unthreaded part are continuous through a tapered portion that is tapered,
The wood material drill screw according to any one of claims 1 to 3.

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