JP2015007475A - Drill screw excellent in workability, and steel structure frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability of a drill screw in order to efficiently fasten a plurality of overlapped shape-steel materials or steel plates (fastening members).SOLUTION: In a drill screw which includes a head part engaging with a rotary tool, a shaft part extending from the head part and having a screw part, and a cutting blade edge formed at an end of the shaft part and having a cutting blade, (i) a cutting edge diameter ratio of the cutting blade edge (=cutting edge diameter/nominal diameter) is 0.900 or more and 0.966 or less. and (ii) a cutting edge angle of the cutting blade edge is more than 120° and 139° or less.

Description

  The present invention relates to a drill screw excellent in workability, and a steel structure frame using the drill screw.

  A drill screw with a drill tip at the tip, used when assembling a steel house by joining members such as steel plates and plywood, is screwed in without drilling a pilot hole in the member. The members are joined together.

  The tip of the drill is carburized and tempered and has a high surface hardness, but its cutting edge is not always sharp compared to a tool dedicated to drilling, and it is a hard member like a steel plate. When fastening, the fastening work is not necessarily efficient.

  In order to increase the efficiency of the fastening work, it is necessary to improve the workability of the drill screw itself, and various improvements have been made so far from the viewpoint of shape and structure (for example, see Patent Documents 1 to 4).

  However, in recent years, the structure of a steel house has become larger and more complicated, and it has been necessary to conclude a plurality of shaped steel materials and steel plates. For example, in the case of a steel house, three or more steel plates having a thickness of 1.0 to 2.3 mm are stacked, and the stacked thickness exceeds 4 mm and reaches about 8 mm, but the cutting edge of the drill screw is worn during the fastening operation, The steel plate cannot be directly drilled and penetrated with a single drill screw, and (a) the drill screw stops in the middle.

  In order to prevent this, at the fastening site, a hole is processed in advance with a steel cone and the like, and then a fastening operation with a drill screw is performed, but the working efficiency is greatly reduced.

  In addition, if the thickness of the steel plates is thick, during the fastening operation, the contact area between the screw thread and the steel plate increases and the frictional resistance increases, and (b) the head of the drill screw flies, The part breaks in the middle. In such a case, the fastening position is changed and the fastening work is performed again, but the work efficiency naturally decreases.

Japanese Patent Laid-Open No. 04-083913 Japanese Patent Laid-Open No. 08-247125 Japanese Patent Laid-Open No. 10-047324 JP 2007-333026 A

  The present invention provides a drill screw that solves the problem by improving the workability of the drill screw in order to efficiently perform the fastening operation even when a plurality of shape steel materials and steel plates are fastened and fastened. For the purpose.

  In order to search for means for solving the above-mentioned problems, the present inventors (x) drill holes smoothly in a fastening member with a drill screw (improvement of fastening workability), and (y) tighten the fastening members together with a drill screw. From the viewpoints of tightening securely (improving fastening reliability) and (z) increasing the nominal diameter of the drill screw to reduce the number of screws (reducing the fastening cost), we are keen on the shape and structure of the drill screw. investigated.

  As a result, the shape and structure of the drill screw satisfying the above (x) to (z) were found. The present invention has been made based on the above findings, and the gist thereof is as follows.

(1) In a drill screw consisting of a head engaging with a rotary tool, a shaft portion provided with a screw portion extending from the head, and a cutting edge having a cutting edge formed at an end portion of the shaft portion,
(I) The cutting edge diameter ratio (= cutting edge diameter / nominal diameter) of the cutting edge is more than 0.900 and not more than 0.966,
(Ii) A drill screw having excellent workability, wherein the cutting edge angle of the cutting edge is more than 120 ° and not more than 139 °.

  (2) The drill screw having excellent workability as described in (1) above, wherein the diameter of a drill screw having a nominal diameter of 4.8 mm is 4.28 to 4.60 mm.

  (3) The drill screw having excellent workability as described in (1) above, wherein the diameter of a drill screw having a nominal diameter of 6.0 mm is 5.32 to 5.75 mm.

  (4) The drill screw having excellent workability according to any one of (1) to (3), wherein a cutting edge length of the cutting edge is 9 to 15 mm.

  (5) A steel structure frame characterized in that a plurality of fastening members are fastened with a drill screw having excellent workability according to any one of (1) to (4).

  (6) The steel structure frame according to (5), wherein the fastening member is a steel plate.

  According to the present invention, it is possible to improve the durability of the cutting edge when cutting a steel plate and reduce the work amount for drilling the steel plate. Therefore, it is possible to directly drill and penetrate the steel plate with a drill screw, thereby reducing the work time. It can be shortened. Since the screwing torque of the drill screw can be reduced, the shaft shaft of the screw can be prevented, and the safety factor (tightening breaking torque / screwing torque) of the screw joint can be increased, so that the work can be performed efficiently and with high safety. Can do.

It is a figure which shows the one aspect | mode of a drill screw. (A) shows a head structure, (b) shows a side structure. It is a figure which shows the aspect of a thread part. It is a figure which shows the aspect of the cutting-blade edge following a thread part. It is a figure which shows an example of a torque curve. It is a figure which shows the relationship between a blade edge | tip diameter ratio and a safety factor. It is a figure which shows the relationship between a blade edge angle (degree) and work amount ratio. It is a figure which shows the relationship between the blade diameter ratio and the blade edge angle (°).

A drill screw excellent in workability of the present invention (hereinafter referred to as “the drill screw 1 of the present invention”) includes a head portion that engages with a rotary tool, a shaft portion that includes a screw portion that extends from the head portion, In the drill screw consisting of a cutting edge having a cutting edge formed at the end,
(I) The cutting edge diameter ratio (= cutting edge diameter / nominal diameter) of the cutting edge is more than 0.900 and not more than 0.966,
(Ii) The cutting edge angle of the cutting edge is more than 120 ° and 139 °.

  Hereinafter, the drill screw of the present invention will be described based on the drawings.

  FIG. 1 shows an embodiment of a drill screw. FIG. 1A shows a head structure, and FIG. 1B shows a side structure. As shown in FIG. 1, the drill screw includes a head portion 1 that engages with a rotary tool (not shown), a shaft portion 2 that includes a screw portion 2 a extending from the head portion 1, and a cutting portion formed at one end of the shaft portion 2. It comprises a cutting edge 3 having a blade 3a.

  In FIG. 2, the aspect of a thread part is shown. A threaded portion having a nominal diameter d1 is formed at a pitch P on a shaft portion having a diameter d2. FIG. 3 shows an aspect of the cutting edge following the thread portion. Following the thread portion, a cutting edge having a cutting edge diameter d3, a cutting edge length y, and a cutting edge angle θ is formed.

  In the drill screw, the cutting edge diameter d3 and the cutting edge angle θ are important factors from the viewpoint of smoothly opening a hole in the fastening member (improving fastening workability).

  Further, from the viewpoints of securely fastening the fastening members together (improvement of fastening reliability) and expanding the nominal diameter of the drill screw to reduce the number of screws (reducing the fastening cost), the cutting edge diameter ratio α ( = Blade diameter d3 / Nominal diameter d1) is an important factor. Therefore, the cutting edge diameter d3 and the nominal diameter d1 are determined by Japanese Industrial Standards (JIS) and Japan Iron and Steel Federation standards.

  However, as described above, for example, when three or more shaped steel members or steel plates are overlapped and fastened, if a standard drill screw is used, (a) the penetration of the drill screw stops halfway, (b) the drill screw And (c) the drill screw frequently breaks along the way.

  Therefore, the present inventors produced drill screws having design dimensions and nominal diameters d1 of 6.0 mm and 4.8 mm by changing the cutting edge diameter d3 and the cutting edge angle θ, and performed a torque test. The torque test was performed at 1200 rpm and 1500 rpm in accordance with the rotational speed of a power tool that is generally used, and the tightening breaking torque TF (Nm) and the screwing torque TD (N.m) were measured. FIG. 4 shows an example of the measurement result. In FIG. 4, TS is (TF + TD) / 2.

  From the measurement results, the amount of work (total value of torque every m seconds from 0 seconds to the time when TF was reached) and the safety factor (= TF / TD) were calculated. The results are shown in Table 1.

  Since the actual dimensions affect the workability, the inventors measure the nominal diameter d1 ′ and the cutting edge diameter d3 ′ of the produced drill screw, and calculate the cutting edge diameter ratio (= cutting edge diameter d3 ′ / nominal diameter d1 ′). Calculated. Table 1 shows the nominal diameter d1 ′, the cutting edge diameter d3 ′, and the cutting edge diameter ratio (d3 ′ / d1 ′). In the following description, d3 ′ / d1 ′ based on measured values of d3 and d1 is used as the blade diameter ratio.

  The work of the drill screw was also evaluated by a work ratio (= work / reference work) in order to compare with the work of the conventional drill screw. The smaller the amount of work, the better.

  The work ratio of a drill screw having a nominal diameter d1: 6.0 mm was calculated using a work with a cutting edge angle θ: 120 ° and a cutting edge diameter ratio d3 ′ / d1 ′: 0.855 as a reference work. The work ratio of a drill screw having a nominal diameter d1: 4.8 mm was calculated using a work with a cutting edge angle θ: 120 ° and a cutting edge diameter ratio d3 ′ / d1 ′: 0.834 as a reference work. The work ratio is preferably smaller than 1.

  Based on the work ratio and the safety factor TF / TD, the performance of the drill screw was comprehensively evaluated according to the criteria shown in Table 2. The safety factor, with reference to the value recommended by the Japan Drill Screw Council, was 4.0 or higher, a safe threshold for screw breakage, 4.0 or higher, and less than 4.0 as x.

  If the work ratio is less than that of the conventional product, workability is good, less than 1.0 is marked as ◯, and 1.0 or more is marked as x. Comprehensive judgment is (a) when safety factor and workload ratio are both ○ (good), (b) when safety factor and workload ratio are both × (bad), (c) safety The case where the rate was ○ and the work ratio was × was evaluated as △ (defective), and the case where the safety rate was × and the work ratio was ○ was determined as ▲ (defective). The results are also shown in Table 1.

  From the above test results, it is understood that the cutting edge diameter ratio α (= cutting edge diameter d3 ′ / nominal diameter d1 ′) and / or cutting edge angle θ greatly affects the workability of the drill screw. Accordingly, the present inventors have confirmed an appropriate range of the cutting edge diameter ratio α and the cutting edge angle θ.

  FIG. 5 shows the relationship between the cutting edge diameter ratio (= cutting edge diameter d3 ′ / nominal diameter d1 ′) and the safety factor. The safety factor is usually 4 or more. As can be seen from FIG. 5, in order to ensure a safety factor of 4.0 or more, the blade diameter ratio needs to be 0.900 or more and 0.966 or less. However, if the cutting edge diameter ratio is 0.900, the safety factor may be predicted to be less than 4.0. Therefore, the cutting edge diameter ratio is set to more than 0.900 and not more than 0.966.

  FIG. 6 shows the relationship between the blade edge angle (°) and the work ratio. If the blade edge angle is more than 120 ° and 139 ° or less, the work ratio is 0.8 or less, and it is understood that the workability of the drill screw is improved.

  FIG. 7 shows the relationship between the cutting edge diameter ratio and the cutting edge angle (°) (see Table 2 for symbols in the drawing). If the cutting edge diameter ratio is maintained above 0.900 and below 0.966 and the cutting edge angle is maintained above 120 ° and below 139 °, the workability of the drill screw can be greatly improved.

  In the drill screw of the present invention, in the case of a drill screw having a nominal diameter of 4.8 mm, the cutting edge diameter is preferably 4.28 to 4.60 mm, and in the case of a drill screw having a nominal diameter of 6.0 mm, the cutting edge diameter is 5.32 to 5. 75 mm is preferred.

  In a drill screw having a nominal diameter of 4.8 mm and a nominal diameter of 6.0 mm, when the cutting edge diameter exceeds the above range, the engagement between the thread and the steel plate is shallow, and tightening may be poor. The cutting edge length of the cutting edge is preferably 9 to 15 mm which is equal to or greater than the thickness of the steel plates. Even if the cutting edge length exceeds this range, good workability can be ensured, but the efficiency at the time of fastening a plurality of fastening members decreases.

  If the drill screw of the present invention is used, it is possible to efficiently manufacture a steel structure frame constituted by fastening a plurality of fastening members (for example, steel plates).

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
Using the drill screws shown in Table 3, steel plates were stacked and fastening work was performed, and the number of fastening failures (intrusion stop, head breakage, intermediate breakage, etc.) was investigated. The results are also shown in Table 3.

  Invention Example 1 and Invention Example 2 are cases in which a drill screw having a cutting edge diameter ratio and a cutting edge angle within the scope of the present invention is used. Comparative Example 1 and Comparative Example 2 are cases where a conventional drill screw is used.

  Using the drill screws of Invention Examples 1 and 2 and Comparative Examples 1 and 2, a test for punching steel sheets having the same number of layers and thickness was performed. According to Invention Examples 1 and 2, it is possible to directly pierce and penetrate a steel plate with a drill screw. Compared to the case of using a conventional drill screw, the drill screw is not penetrated, the head of the drill screw and the shaft breakage. It can be seen that the number of fastening failures is greatly reduced.

  As described above, according to the present invention, a steel plate can be directly drilled and penetrated with a drill screw, work time can be shortened, screw shaft breakage can be prevented, and screw joining can be performed. The safety factor (screwing torque / tightening breaking torque) can be increased, and work with high safety can be performed efficiently. Therefore, the present invention has high applicability in the construction industry.

1 Head 2 Shaft 2a Screw 3 Cutting edge 3a Cutting blade

Claims (6)

In a drill screw composed of a cutting blade tip having a cutting edge formed at a head portion engaging with a rotary tool, a shaft portion provided with a screw portion extending from the head portion, and an end portion of the shaft portion,
(I) The cutting edge diameter ratio (= cutting edge diameter / nominal diameter) of the cutting edge is more than 0.900 and not more than 0.966,
(Ii) A drill screw having excellent workability, wherein the cutting edge angle of the cutting edge is more than 120 ° and not more than 139 °.   The drill screw with excellent workability according to claim 1, wherein a tip diameter of the drill screw having a nominal diameter of 4.8 mm is 4.28 to 4.60 mm.   The drill screw with excellent workability according to claim 1, wherein a tip diameter of the drill screw having a nominal diameter of 6.0 mm is 5.32 to 5.75 mm.   The drill screw with excellent workability according to any one of claims 1 to 3, wherein a cutting edge length of the cutting edge is 9 to 15 mm.   A steel structure frame, wherein a plurality of fastening members are fastened with a drill screw having excellent workability according to any one of claims 1 to 4.   The steel structure frame according to claim 5, wherein the fastening member is a steel plate.

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