JP5908830B2 - Wood screw - Google Patents

Description

  The present invention relates to a wood screw used for installing and fixing a device outside a house without impairing the waterproof property of the house.

  Conventionally, wood screws have been installed outside the house to install and fix power generation equipment such as solar cells, solar water heaters, radio signal receiving antennas, outdoor lighting equipment, and air conditioner outdoor units without compromising the waterproofness of the house. It is used.

  The double thread screw disclosed in Patent Document 1 has a large advance angle per one screw rotation, so that the working time can be shortened. However, since the insertion torque is large, the output torque of the electric torque driver needs to be set high. . On the other hand, since the hardness of the wood varies, if the screw tightening operation is performed with a high output torque set, the wood into which the wood screw has been driven will be destroyed and the screw will idle, resulting in the retention force of the wood screw. There is a problem that can not be.

  As a technique for reducing the insertion torque, there is a method of reducing the insertion torque by providing a function of cutting wood or concrete by forming a wood screw tip into a drill shape as in Patent Document 2. . Further, as a technique for preventing the corrosion of wood screws, there is a method of coating the surface with a resin as in Patent Document 3.

Japanese Patent No. 4886214 Japanese Patent No. 4684169 JP 2002-330221 A

  However, according to the above-mentioned Patent Document 2, in a use in which a high-viscosity rubber for waterproofing and wood or concrete are combined and penetrated, the high-viscosity rubber clings to the drill part at the tip and the high-viscosity rubber is in the groove of the drill part. There was a problem that the insertion torque could not be reduced because the function of clogging and scraping off wood chips and concrete fragments could not be fully exhibited.

  Further, according to Patent Document 3, there is a problem that even if the tip has a drill shape, the resin covers a sharp corner portion having a cutting function of the drill portion, so that the drillability of the drill portion is lowered.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the wood screw which suppresses the increase in insertion torque also in the use which penetrates the high-viscosity rubber | gum for waterproof use, and wood together.

  In order to solve the above-described problems and achieve the object, the present invention includes a head that receives a rotational force, a shank having a cylindrical shaft portion, and a screw tip having a conical shape. Wood screws having a double thread straddling the shaft portion and the shaft portion, and at least four are formed on the screw tip portion so as to extend to the tip of the screw tip portion at a rotationally symmetrical and equidistant interval around the rotation axis of the shank. A V-shaped groove is provided, and the member to be screwed is perforated at the edge of the V-shaped groove by receiving a rotational force at the head and rotating.

  According to the present invention, it is possible to suppress an increase in insertion torque even in an application in which a high-viscosity rubber for waterproofing and wood or concrete are penetrated together.

FIG. 1 is a side view showing a configuration of an embodiment of a wood screw according to the present invention. FIG. 2 is a top view showing the configuration of the embodiment of the wood screw according to the present invention. FIG. 3 is an enlarged view of the shaft portion. FIG. 4 is a cross-sectional view of the wood screw at the screw tip. FIG. 5 is a side view of a fastening member in which a wood screw, a washer, and a waterproof packing are combined. FIG. 6 is a diagram illustrating the fastening member in a state where the washer and the waterproof packing are inserted to the top of the shaft portion. FIG. 7 is a cross-sectional view showing a state where the bracket is placed on the roof of the house. FIG. 8 is a diagram illustrating a state in which the wood screw that has penetrated the first, second, and third waterproof sheets has reached the wood. FIG. 9 is a diagram schematically showing how the fragments of the first, second, and third waterproof sheets enter the V-shaped groove. FIG. 10 is a diagram illustrating a state in which the wood screw has been screwed in. FIG. 11 is a cross-sectional view showing a state of the waterproof packing when the wood screw has been screwed in. FIG. 12 is a diagram showing the relationship between the diameter at the first thread portion, the average pull-out strength, and the standard deviation σ.

  DESCRIPTION OF EMBODIMENTS Embodiments of a wood screw according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a side view showing a configuration of an embodiment of a wood screw according to the present invention. FIG. 2 is a top view showing the configuration of the embodiment of the wood screw according to the present invention. The wood screw 10 has a head portion 11, a shaft portion 12, and a screw tip portion 13. The head 11 is hexagonal and is provided with a cross hole 111. For this reason, the wood screw 10 can be tightened or loosened using either a wrench or a screwdriver. The seating surface 112 of the head 11 projects in a flange shape. As for the axial part 12, the shank 12a is cylindrical. The screw tip portion 13 has a full point shape, and the shank 13a has a conical shape. A double thread consisting of a first thread 14 and a second thread 15 is formed from the screw tip 13 to the shaft 12. FIG. 3 is an enlarged view of the shaft portion. The double thread is formed such that the diameter D ₁ at the first thread 14 is larger than the diameter D ₂ at the second thread 15.

The neck portion 113 of the head portion 11 is formed in a tapered shape so that the diameter increases from D ₃ to D ₅ from the shank 12 a of the shaft portion 12 toward the head portion 11. The diameter D ₅ of the base of the neck 113 is larger than the diameter D ₁ at the first thread 14 portion.

  The screw tip portion 13 is provided with four V-shaped grooves 16 that are rotationally symmetrical and equidistant about the rotation axis of the shank 13 a of the screw tip portion 13. At least one of the V-shaped grooves 16 has a length equal to or greater than the thickness of the wood into which the wood screw 10 is to be driven. The V-shaped groove 16 may reach the shaft portion 12. FIG. 4 is a cross-sectional view of the wood screw at the screw tip, showing a cross section taken along line IV-IV in FIG. 1. The V-shaped groove 16 has a gentle arc shape at the ridgeline of the bottom portion 16a. In the V-shaped groove 16, the distance from the center of the shank 13a to the ridge line of the bottom 16a is longer on the head 11 side than on the screw tip 13 side. In other words, the V-shaped groove 16 has an arcuate bottom and is shallower toward the head 11 side. The edge 16b of the V-shaped groove 16 has an edge shape.

The wood screw 10 has a relationship that satisfies 2D ₁ > T and 1.65> (D ₁ / D ₃ )> 1.55, where T is the thickness of the wood into which the wood screw 10 is driven. By satisfying this condition, it is possible to make both the value of the pulling strength from the timber that has been laid down and the small variation in the value compatible, which will be described later.

  The entire surface of the wood screw 10 is covered with the resin layer 17, and the weather resistance is enhanced. For the purpose of improving the weather resistance, the resin layer 17 does not need to be provided on the entire surface of the wood screw 10, and is provided on at least a portion protruding through the wood on the tip side and the head 11. Just do it.

  The wood screw 10 according to the embodiment is used as a fastening member in combination with the washer 21 and the waterproof packing 22. FIG. 5 is a side view of a fastening member in which a wood screw, a washer, and a waterproof packing are combined. The washer 21 and the waterproof packing 22 are passed through the shaft portion 11 of the wood screw 10 in this order. FIG. 6 is a diagram illustrating the fastening member in a state where the washer and the waterproof packing are inserted to the top of the shaft portion.

Washer 21 is formed of stainless steel as a material, an inner diameter of D _4. The material of the washer 21 may be other than stainless steel (such as iron) as long as it is a metal material. The inner diameter D _{4 of the} washer 21 is larger than the diameter D ₁ at the first screw thread 14 portion of the wood screw 10 and smaller than the diameter D ₅ of the root of the neck 113 of the wood screw 10 (D _{5> D 4> D 1)} . Since D ₅ > D ₄ > D ₁ , the washer 21 stops in the middle of the taper of the neck 113 of the wood screw 10 and cannot be inserted until it contacts the seat surface 112. The waterproof packing 22 is formed using a known general resin material such as natural rubber or nitrile rubber as a raw material. The inner diameter D ₆ of the waterproof packing 22 is larger than the diameter D ₅ of the base of the neck 113 of the wood screw 10. It has become smaller (D ₅ > D ₆ ).

Taking an example of the dimensions of each part of the fastening member according to the embodiment in the case of driving into a wood having a thickness of 12 mm, the wood screw 10 has a diameter D ₁ = 6.3 mm at the _first thread 14 portion, the second The diameter D ₂ of the screw thread 15 is 5 mm, the diameter D ₃ of the shank 12 a of the shaft portion 12 is 4 mm, the diameter D ₅ of the root of the neck 113 is 6.7 mm, and the V-shaped groove 16 is Four, the V-shaped opening angle is about 60 °, and the length of the V-shaped groove is about 12 mm. The washer 21 has an inner diameter D ₄ = 6.5 mm. The waterproof packing 22 has an inner diameter D ₆ = 4.8 mm. Note that these values are merely examples, and the present invention is not limited to these values.

  The fastening member according to the embodiment is used when an article (such as a bracket for installing a solar cell module) is fixed on the roof of a house. FIG. 7 is a cross-sectional view showing a state where the bracket is placed on the roof of the house. The roof of the house includes a timber 30, a first waterproof sheet 40, a first roof material 50, a second roof material 60 and a third roof material 70. A waterproof sheet 80 and a third waterproof sheet 90 are added.

  The wood 30 is a plywood or the like, and has a thickness T = 9 mm or more. The wood 30 is provided as a field board on the roof of the house.

  The first waterproof sheet 40 is a rubber / asphalt-based waterproof sheet for a roof base, and is laid on a wood 30 that is a field board.

  The first, second and third roofing materials 50, 60, 70 are decorative slate, and are wound on the first waterproof sheet 40 so as to overlap each other, and screws (not shown) are used. Part is fixed to the wood 30 by using. In installing the bracket 100, pilot holes 61 and 71 are formed in the second roof material 60 and the third roof material 70 by drilling or the like.

  The bracket 100 includes a mounting hole 101, which is installed so that the mounting hole 101 overlaps the lower holes 61, 71 of the second roof material 60 and the third roof material 70. It is fixed on the roof material 70. A solar cell module (not shown) is fixed to the bracket 100 later.

  The second waterproof sheet 80 is a rubber / asphalt waterproof sheet and is inserted with the gap between the second roof material 60 and the third roof material 70 widened. The second waterproof sheet 80 prevents rainwater from entering the pilot holes 61 and 71 of the second roof material 60 and the third roof material 70.

  The third waterproof sheet 90 is made of butyl rubber. The third waterproof sheet 90 prevents rainwater from entering through the mounting hole 101 of the bracket 100 and rainwater from entering the prepared hole 71 of the third roofing material 70 through the back of the bracket 100. In addition, what is necessary is just to provide the 1st waterproof sheet 40, the 2nd waterproof sheet 80, and the 3rd waterproof sheet 90 as needed. Only one of the first waterproof sheet 40, the second waterproof sheet 80, and the third waterproof sheet 90 may be provided, or all of the three kinds may be provided.

  The first, second, and third waterproof sheets 40, 80, 90 are not subjected to pilot hole processing before the wood screw 10 is inserted.

  FIG. 8 is a diagram illustrating a state in which the wood screw that has penetrated the first, second, and third waterproof sheets has reached the wood. FIG. 9 is a diagram schematically showing how the fragments of the first, second, and third waterproof sheets enter the V-shaped groove. The wood screw 10 is inserted into the mounting hole 101 and the lower holes 61 and 71 and rotated so that the edge 16b of the V-shaped groove 16 has the first, second and third waterproof sheets 40 and 80. , 90 are cut and the first, second and third waterproof sheets 40, 80, 90 are broken. When the wood screw 10 breaks through the first, second and third waterproof sheets 40, 80, 90, the rubber piece 110 clinging to the screw tip portion 13 and the shaft portion 12 enters the V-shaped groove 16. Since the V-shaped groove 16 is shallower toward the head 11 side, the rubber piece 110 that has entered the V-shaped groove 16 is discharged to the head 11 side. Therefore, when the wood screw 10 penetrating the first, second and third waterproof sheets 40, 80, 90 pierces the wood 30, the V-shaped groove 16 is not clogged. There is no loss.

  Since the V-shaped groove 16 is provided with a length substantially the same as the thickness of the wood 30, the rubber pieces 110 and the wood chips that have entered the V-shaped groove 16 are also screwed into the wood screw when the hole is made in the wood 30. 10 is discharged to the head 11 side. Thereby, it becomes difficult for wood chips to bite between the wood screw 10 and the wood 30 fastened to the wood 30, and the wood screw 10 can be prevented from loosening.

  The valleys of the first screw thread 14 and the second screw thread 15 are covered with the resin layer 17 and have a higher surface friction resistance than the metal surface treatment or the wood screw of the metal cloth material. The second and third waterproof sheets 40, 80, 90 are easy to stick together. For this reason, the highly viscous first, second and third waterproof sheets 40, 80, 90 can easily enter between the wood screw 10 driven into the wood 30 and the wood 30. The effect which prevents the rainwater which penetrate | invades between is acquired. On the other hand, the first, second and third waterproof sheets 40, 80 in which the corner (edge 16 b) having the wood cutting function of the V-shaped groove 16 is covered with the resin layer 17 and clinging to the surface of the wood screw 10. , 90 increases the insertion torque, but by providing four V-shaped grooves 16, a cutting ability approximately four times that of a single V-shaped groove 16 can be obtained. And can suppress an increase in insertion torque. Therefore, an increase in insertion torque can be suppressed even if the outer shape of the thread is formed large in order to increase the pulling strength with respect to the wood 30.

FIG. 10 is a diagram illustrating a state in which the wood screw has been screwed in. The waterproof packing 22 is sandwiched between the washer 21 and the bracket 100. FIG. 11 is a cross-sectional view showing a state of the waterproof packing when the wood screw has been screwed in. Since D ₅ > D ₄ , the washer 21 is stopped in the middle of the taper of the lower neck 113, and there is no gap between the lower neck 113 of the wood screw 10 and the washer 21. Further, since D ₅ > D ₆ , the tapered neck portion 113 of the wood screw 10 is inserted into the waterproof packing 22 so as to expand the hole. Thereby, rain water can be prevented from entering from the neck 113 of the wood screw 10 through the inside of the washer 21.

As an example, the material is stainless steel, the diameter D ₁ = 6.3 mm at the first thread portion, the diameter D ₂ = 5 mm at the second thread portion, and the diameter D of the shank 12a of the shaft portion. Wood screws were formed with ₃ = 4 mm and a diameter D ₅ = 6.7 mm at the bottom of the neck. Four V-shaped grooves with an opening angle of about 60 ° were formed in the screw tip, and the length of each groove was approximately 12 mm. On the entire surface of the wood screw, a metal zinc layer, a special chemical conversion coating layer, and a surface fired layer using a polyester material were formed in this order.

  As Comparative Example 1, a wood screw having one V-shaped groove and the other being the same as in the example was prepared.

  As Comparative Example 2, a wood screw was prepared in which the V-shaped groove was not provided and the others were the same as in the example.

  A test piece was prepared using a structural plywood having a thickness of 12 mm, and the wood screw of Example, Comparative Example 1 or Comparative Example 2 was screwed with a general electric screwdriver capable of torque management, The torque value causing idling was measured. Table 1 shows the measurement results of the torque value at which the screw is tightened and the torque value at which idling occurs.

  The idling torque is a substantially constant value regardless of the number of V-shaped grooves, but the insertion torque is the smallest when there are four V-shaped grooves. For this reason, the management range of the torque at the time of screwing in the wood screw can be set wide by increasing the number of V-shaped grooves. The maximum value of the insertion torque is almost the same regardless of the number of V-shaped grooves, but the minimum value of the insertion torque is four V-shaped grooves and one V-shaped groove. It is smaller than the case. This confirmed that it is preferable to provide four or more V-shaped grooves.

  Next, the pullout strength of the wood screw was verified. A test piece was prepared using a structural plywood having a thickness of 12 mm. The wood screw of the example was placed at the center of the test piece, a gap was formed between the field ground and the neck, and the screw was screwed into the test piece using an electric screwdriver. The head of the wood screw was chucked and a tensile load was applied.

As Comparative Example 3, a wood screw having a diameter D ₁ = 6.7 mm at the first screw thread portion and the other portions being the same as in the embodiment was prepared, and using an electric screwdriver in the same manner as the wood screw in the embodiment. The test piece was screwed, the head of the wood screw was chucked, and a tensile load was applied.

As Comparative Example 4, the diameter D ₁ = 6.4 mm at the first thread portion and the diameter D ₂ = 6.4 mm at the second thread portion, and the other portions were the same as in the example. A wood screw was prepared and screwed into a test piece using an electric screwdriver in the same manner as the wood screw of the example, and a tensile load was applied by chucking the head of the wood screw.

As Comparative Example 5, a wood screw having a diameter D ₁ = 5.6 at the first screw thread portion and a diameter D ₃ = 3.5 mm of the shank 12a of the shaft portion, and the other portions being the same as in the embodiment was prepared. Then, similarly to the wood screw of the example, it was screwed into the test piece using an electric screwdriver, and the head of the wood screw was chucked to apply a tensile load.

As Comparative Example 6, a wood screw having a diameter D ₁ = 5.15 mm at the first screw thread portion and a _single V-shaped groove was created and tested using an electric screwdriver in the same manner as the wood screw of the example. The sample was screwed into a piece, the head of the wood screw was chucked, and a tensile load was applied. In addition, the comparative example 6 is corresponded to the wood screw currently generally used for fixation of articles | goods to the roof etc. of a house now.

  Table 2 shows the measurement results of the pulling strength.

Based on the examples and comparative examples 3 to 6, the relationship between the height of the first thread and the drawing strength was examined. FIG. 12 is a diagram showing the relationship between the diameter at the first thread portion, the average pull-out strength, and the standard deviation σ. As the diameter D ₁ at the first thread portion increases, the pullout strength increases linearly. In the case of Comparative Example 3 where D ₁ = 6.7 mm, the current ratio is 30%, and D ₁ = 6. In the case of the 3 mm embodiment, the strength was improved by about 20% compared with the current ratio.

  When Comparative Example 3 is compared with Examples, the average value exceeds that of Comparative Example 3, but the variation (standard deviation) is large. This is considered to be because the test piece (base material) is broken because the height of the first thread is too high. In Comparative Example 3, the crack of the test piece at the time of screwing was larger than that of the example.

In Comparative Example 4 Example, the diameter D ₁ of the part of the first thread is approximately the same value, draw resistance but is almost equivalent diameter D ₁ of the part of the first thread When towards the second threaded portion diameter at D ₂ are equal Comparative example 4 tended cracking during screwing it is large.

In the example, 2D ₁ (= 12.6) <T and (D ₁ / D ₃ ) = 1.58, the value of the pulling strength is large, and the variation in the values is also small. In Comparative Example 3, (D ₁ / D ₃ ) = 1.68 (> 1.65), and the variation in the drawing strength is large. In Comparative Example 5, 2D ₁ (= 11.2) <T and the pullout strength is small. In Comparative Example 6, 2D ₁ (= 10.3) <T and (D ₁ / D ₃ ) = 1.29 (<1.55), and the pullout strength is small.

Based on the above results, satisfying the relationship of 2D ₁ > T and 1.65> (D ₁ / D ₃ )> 1.55, where T is the thickness of the wood into which the wood screw is driven. Thus, it was confirmed that both the value of the pulling strength value and the small variation in value can be achieved.

  In the above embodiment, the configuration in which four V-shaped grooves are provided in the screw tip portion is an example. However, the number of V-shaped grooves may be any number as long as there are four or more. it can. In the above example, the target to be screwed is a structural plywood, but it is used for concrete formwork or other plywood, or a structural wooden board or small-diameter wood that has been compressed by stacking thin thin pieces of rectangular wood. The same applies to other materials mainly composed of wood, such as particleboard molded with high-temperature and high-pressure, hardwood chipped cement board in which wood and cement are kneaded and compression-molded, with adhesive added to small pieces of wood that have been finely cut The effect is obtained.

  Since the wood screw according to the embodiment has a large difference between the insertion torque and the idling torque, it is difficult to cause the wood screw idling due to the variation in the torque of the electric screwdriver or the density of the wood due to the difference in the location where the wood screw is driven. It is possible to prevent rainwater or the like from entering the interior of the house or the like through the gap formed by destroying the structure, and to improve the durability of the house or the like. In addition, since the pulling strength is improved, the number of wood screws and washers and waterproof packings used in association therewith can be reduced, and the amount of raw materials can be reduced.

  As described above, the wood screw according to the present invention is useful in that the pulling strength is strong and the insertion torque is small, and the waterproof property of the house is particularly provided at the place where the waterproof sheet such as the roof of the house is installed. Suitable for fixing articles so as not to damage.

  10 Wood Screw, 11 Head, 12 Shaft, 12a, 13a Shank, 13 Screw Tip, 14 First Thread, 15 Second Thread, 16 V-shaped Groove, 16a Bottom, 16b Edge, 17 Resin Layer, 21 washer, 22 waterproof packing, 30 wood, 40 first tarpaulin, 50 first roofing material, 60 second roofing material, 61, 71 pilot hole, 70 third roofing material, 80 second Waterproof sheet, 90 3rd waterproof sheet, 100 bracket, 101 mounting hole, 110 rubber piece, 111 cross hole, 112 seating surface, 113 under neck.

Claims (2)

A wood screw having a head receiving a rotational force, a shank having a cylindrical shaft portion, and a screw tip portion having a conical shank shape, and having a double thread extending over the screw tip portion and the shaft portion,
Only the screw tip portion includes V-shaped grooves formed at least four so as to extend to the tip of the screw tip portion at rotationally symmetrical and equidistant intervals around the rotation axis of the shank.
The double thread has a first thread and a second thread,
The diameter D ₁ at the _first thread portion is larger than the diameter D ₂ at the second thread portion ,
When the diameter of the shank of the shaft portion is D ₃ and the thickness of the member to be screwed is T,
2D ₁ > T and 1.65> (D ₁ / D ₃ )> 1.55
Satisfy the relationship
Wherein a rotational force by rotating is received by the head, characterized by perforations in the edges of grooves of said V-shaped in the screwing target member wood screws. 2. The wood screw according to claim 1 , further comprising a resin layer that covers at least a portion of the shaft portion that protrudes through the screw target member, the screw tip portion, and the head portion.

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