JP6467319B2 - Tapping screw - Google Patents

Description

  The present invention relates to a tapping screw that forms a female screw by tightening, and more particularly to a tapping screw that is suitable for fastening a thin plate having a thickness of 0.8 to 1.6 mm.

  The tapping screw is a screw having a higher hardness than the member to be fastened, and the female screw is cut and formed on the member to be fastened by tightening. Chipping, that is, cutting waste, is generated during cutting, which may cause a problem. The tapping screw is also used for fixing a heat insulating sheet or a waterproof sheet laid on the surface of a metal roof of a factory, a warehouse, an office, a gymnasium or the like to the metal roof.

  The tapping screw may be hardened by overheating austenitic stainless steel, or may be hardened by quenching or nitriding the martensitic stainless steel. The tapping screw is provided with a head at one end of a cylindrical body, and a groove for engaging a driver bit is formed. The other end is provided with a “bite portion” that bites into the fastened member. A male screw is formed from the biting portion to the trunk portion.

  A helical male screw is provided on the biting portion and the trunk portion. FIG. 6 is a cross-sectional view of a male screw provided on a general tapping screw. The male screw is composed of two slopes toward the trunk and an apex portion sandwiched between the both slopes. Of the two slopes, the surface on which the screw advances during fastening is referred to as the advance flank surface, and the other surface is referred to as the return flank surface. When a plane that passes through the top and is orthogonal to the central axis of the trunk is defined as an orthogonal plane, an angle formed by the orthogonal plane and the advancing flank surface is referred to as an advancing flank angle. The angle formed by the orthogonal plane and the return flank is referred to as the return flank angle. When the tapping screw is fastened, both flank surfaces contribute to the formation of the female screw, but after fastening, pressure is applied to the return-side flank surface to maintain the fastened state.

  The tapping screw described in Patent Document 1 is a screw that is fastened while a female screw is cut and formed on a member to be fastened having a prepared hole. According to paragraphs 25 to 31 of the same document, the male screw of the tapping screw that has been widely used in the related art is substantially symmetrical, and both flank angles are about 30 degrees. Furthermore, this document describes a tapping screw that reduces the return pressure applied to the female screw after completion of fastening by reducing the return-side flank angle, thereby reducing the destruction of the female screw and fatigue of the fastened member. Yes. Specifically, the return flank angle is 5 degrees and the advance flank angle is 30 degrees, and the angle of the male screw is as sharp as 35 degrees, which is the sum of these angles.

  The tapping screw described in Patent Document 2 is also a screw that is fastened while a female screw is cut and formed on a member to be fastened having a prepared hole. This tapping screw has a symmetrical male screw, but it is called a female screw forming part near the tip, and the male screw formed with a larger flank angle and a slightly higher height than the others. Have. It is intended to reduce the cutting friction by concentrating the force for forming the female thread on the female thread forming portion for one mountain. According to the document, in order to increase the cutting efficiency, it is effective that the cross-sectional angle of the male screw, that is, the sum of both flank angles is 50 degrees or less, and the angle of the female screw forming portion is larger than this. It is said that it should be increased by about 10 degrees.

  Furthermore, in this document, a coating material for adsorbing and holding female thread forming scraps between screw threads is applied to 60% or more of the biting portion and the trunk portion (described as the trunk portion and the leg portion in the same literature). Is described. FIG. 2 of the same document shows a covering material applied thickly at the valley of the male screw. It is described that this covering material prevents cutting chips from falling when the tapping screw is screwed.

  The screw described in Patent Document 3 is also based on the premise that a pilot hole has been made in advance in a member to be fastened. In the screw described in this document, an adhesive material is applied to the thread forming portion and the male screw. This is intended to prevent chips from falling by adsorbing and holding chips generated by the thread forming portion by cutting the member to be fastened.

JP 2005-127369 A JP 2004-36733 A JP 2008-175253 A

  A tapping screw described in Patent Document 1 that has a sharp male screw of about 35 degrees throughout is considered to have a high cutting efficiency of the female screw. However, if the tip is provided with a similar sharp male screw, the burring generated when cutting into the fastened member may be cut and relatively large cutting waste may be generated. Was.

  The tapping screw described in Patent Document 2 is to be screwed after a pilot hole is made in advance. Therefore, there is a problem that if a pilot hole is made on site such as repairing a roof, a large amount of cutting waste is generated and all of them are dropped. If the pilot hole cannot be machined in advance elsewhere, such as when repairing a roof, it must be a tapping screw that does not require a pilot hole.

  The tapping screw described in Patent Document 3 does not have a mechanism for reducing chips. Therefore, when large chips are generated, there is a problem that the chips may fall without being adsorbed by the adhesive resin. In the first place, the screw described in the document also requires a pilot hole, and there is a problem that a large amount of cutting waste is dropped when the pilot hole is opened.

  All of the patent documents shown above are based on the premise that a pilot hole is previously formed in a member to be fastened. However, the restoration of the roof is an operation performed on the roof of the building in use, and it is not possible to make a pilot hole in advance elsewhere. However, it is not allowed to make a large amount of cutting waste by making a pilot hole in the roof plate as a member to be fastened. Therefore, in the work, it is necessary to lay a curing sheet below the roof plate so that the cutting waste does not fall into the living space. Laying the curing sheet is a work that you want to avoid if possible because it increases the cost significantly.

  Accordingly, an object of the present invention, that is, a technical problem to be solved, is a tapping screw that does not require a pilot hole, and provides a tapping screw that does not generate chips when fastening or prevents chips from falling. There is.

  Therefore, the invention according to claim 1 is provided, wherein a cylindrical body is provided with a head at one end and a bite at the other end, and a male screw is formed in a spiral shape from the bite to the trunk. The bite portion has a conical shape whose apex angle ranges from 26 degrees to 29 degrees, and the bite portion has three or more symmetrical male threads on the surface of the bite portion. Is provided with a male screw having an asymmetric cross section with a return side flank angle smaller than the advancing flank angle, and a part of the body portion is covered with an adhesive material from the leading end of the biting portion, When the diameter of the hole is increased, the surface of the adhesive material is peeled off, and the peeled adhesive material fills a gap generated between a screw trough and the member to be fastened. The above-mentioned problem is solved by using a tapping screw. It was.

  According to a second aspect of the present invention, in the tapping screw according to the first aspect, a cross-sectional angle of the male screw having the symmetric cross section is 60 degrees or more, and a cross-sectional angle of the male screw having the asymmetric cross section is 40 degrees or less. The above-mentioned problems have been solved by using a tapping screw characterized by

  According to a third aspect of the present invention, there is provided the tapping screw according to the second aspect, wherein the return side flank angle of the male screw having the asymmetrical cross section is 10 degrees or less. Settled.

  According to a fourth aspect of the invention, there is provided a tapping screw according to any one of the first, second, and third aspects, wherein the tapping screw penetrates a non-fastened object and a region connected to the penetrating part. The above-mentioned problem was solved by using a tapping screw characterized in that the portion was covered with the adhesive material.

  According to a fifth aspect of the present invention, in the tapping screw according to any one of the first, second, third, and fourth aspects, the adhesive material is an emulsified acrylic resin adhesive material. The above-mentioned problem has been solved by using a tapping screw to be used.

  According to a sixth aspect of the present invention, in the tapping screw according to any one of the first, second, third, fourth, and fifth aspects, the tapping screw has a washer that engages with the head. The above-mentioned problem has been solved by using the tapping screw as a feature.

  In the tapping screw according to claim 1, the biting portion has a conical shape with a tip angle in the range of 26 degrees to 29 degrees, so that there is little possibility that the biting section will break even when pressed against the member to be fastened. On the other hand, since the pressing force is concentrated on the tip, there is an effect that the surface of the fastened member can be locally concave.

  Further, three or more male screws are provided in the conical bite portion. With this configuration, the spiral diameter of the male screw gradually increases from the leading end of the biting portion for each mountain. With this configuration, each time the tapping screw of the present invention rotates 360 degrees, the hole diameter of the fastened member increases. Since the hole diameter gradually expands, the burring generated with the expansion increases, but there is an effect of reducing the possibility of being cut and dropped.

  Further, the body portion is provided with a suitable number of male threads having an asymmetric cross section so that the return side flank angle is small. Since the return side flank angle is small, there is an effect that the return pressure is dispersed and the burden on the fastened member is light. Further, by dispersing the stress to the fastened member, there is an effect of preventing the deformation of the member and improving the holding force.

  Furthermore, in the tapping screw according to claim 1, the tapping screw is covered with an adhesive material from the leading end of the biting portion to the trunk portion. When the male screw cuts and forms the female screw, it is adsorbed by the adhesive material even when chips are generated, so that there is an effect of further reducing the possibility of the chips falling. Further, when the conical bite portion gradually enlarges the hole diameter of the fastened member, the surface of the applied adhesive material is efficiently peeled off and collected on the fastened member. There is an effect of efficiently filling a gap between the hole of the member to be fastened and the male screw valley having the asymmetrical cross section provided in the body portion. Thereby, it has the effect which interrupts | blocks a chip passing through the hole of the said to-be-fastened member, and prevents falling below.

  In the tapping screw according to claim 2, since the advance side flank angle of the male screw provided in the biting portion is an obtuse angle of 60 degrees or more, there is little possibility of cutting the burring caused by the biting. There is an effect that there is little possibility that large burring waste is generated.

  In the tapping screw according to a third aspect of the present invention, the return side flank angle of the male screw having the asymmetric cross section is configured to be as small as 10 degrees or less. Thereby, there is an effect that the return pressure is reliably dispersed and the burden on the fastened member is light. Further, by dispersing the stress to the fastened member, there is an effect of preventing the deformation of the member and improving the holding force.

  In the tapping screw according to the fourth aspect, since the region penetrating the fastened member is covered with the adhesive material, there is an effect that the generated chips are reliably adsorbed. In addition, even if a gap between the valley of the tapping screw and the hole of the fastening member is generated, the adhesive material blocks the chip, thereby preventing the chip from penetrating and dropping. .

  In the tapping screw according to claim 5, since the adhesive material is an emulsified acrylic resin adhesive material, there is an effect of reducing environmental load.

  In the tapping screw according to the sixth aspect, since the washer that engages with the head of the tapping screw widely disperses the pressure applied to the waterproof sheet, there is an effect that the possibility that an excessive load is applied to the prevention sheet is reduced.

(A) is the front view of an example of the tapping screw of this invention fastened, (B) is an enlarged view of the biting part and front end side trunk | drum of the tapping screw. (A) and (B) are cross-sectional views of a symmetric male screw and an asymmetric male screw formed from the biting part to the body part in the tapping screw of the present invention, (C1), (C2), (C3) and (C C4) is a sectional view of the transition state male screw. (A) is sectional drawing of the asymmetrical male screw concerning the tapping screw of this invention, (B) is sectional drawing of the symmetrical male screw concerning the tapping screw. (A) is a partial front view of a second embodiment of a tapping screw according to the present invention, (B) is an enlarged cross-sectional view of a δ region that is a part of an application portion of an adhesive material, and (C) is a tapping screw of the same. The figure of a mode that the to-be-fastened member was fastened, (D) is a principal part cross-section enlarged view of (C). These are the tapping screws of 3rd Embodiment of the tapping screw based on this invention, Comprising: It is the front view constructed with the tapping screw which attached the washer. Is a cross-sectional view of a general male screw.

  FIG. 1A is a front view of an example of a tapping screw of the present invention that is fastened. The tapping screw 1 includes a head portion 2 at one end of the body portion 3 and a biting portion 4 at the other end. The head 2 is provided with a groove in which a driver bit is engaged when tightening.

  The interval between the male threads of the tapping screw 1 is 1.5 to 2.5 millimeters. The tapping screw 1 is a screw for fastening a thin plate having a thickness of 1.6 mm or less. When fastened, the number of female screws formed in the thin plate is 1 or less. Therefore, after the fastening, the biting portion 4 of the tapping screw 1 remains in a state of penetrating the fastened member 7.

  The fastened member 7 is a member made of, for example, a metal plate, resin, wood, or the like, and specifically, a deck plate, a roof plate, or the like. The head 2 remains in contact with the surface of the waterproof sheet 8. Further, the space between the waterproof sheet 8 and the fastened member 7 may be filled with a filler 9 for the purpose of heat insulation and sound insulation. As the filler 9, for example, a hard urethane board can be used.

  In fastening the fastened member 7 with the tapping screw 1, a rotational force and a pressure in the normal direction of the fastened member 7 are applied via a driver bit engaged with the head 2. Then, the biting portion 4 cuts and forms the female screw in the fastened member 7. After the to-be-fastened member 7 is penetrated, the tapping screw 1 remains in the region of the body portion 3. An asymmetric male screw 51 is formed in the body 3, and this prevents the tapping screw 1 from coming off. This will be described later together with the return pressure.

  FIG. 1B shows a tip portion of the tapping screw 1 according to the present invention, that is, a portion from the biting portion 4 to the trunk portion 3. A symmetric male screw 53 is formed at the distal end portion 4, and an asymmetric male screw 51 is formed at the body portion 3.

  In the course of transition from the symmetric male screw 53 to the asymmetric male screw 51, a transition state male screw 52 is appropriately formed. Although the male screw 5 is spiral, for example, if the transition from the symmetric male screw 53 to the asymmetric male screw 51 is completed while rotating 360 degrees, the transition-state male screw 52 has one peak. That is, 360 degrees are formed. The transition state male screw 52 gradually transitions from the symmetric male screw 53 to the asymmetric male screw 51 between 360 degrees. This example will be described later.

  Further, when transitioning from the symmetric male screw 53 to the asymmetric male screw 51 during 180 degrees, the transition state male screw 52 is provided for 180 degrees. In any case, the transition state male screw 52 is formed from the biting portion 4 to the trunk portion 3.

  FIG. 2 shows a cross-sectional view of the tapping screw 1 according to the present invention. 2A and 2B show the same cross-sectional view of the tip portion of the tapping screw 1. 2A is a diagram showing the angle of the tip, and FIG. 2B is a diagram showing the position of the cross-sectional view of the transition state male screw. As shown in FIG. 2A, the apex angle of the biting portion 4 is α. α is in the range of 26 to 29 degrees. Accordingly, the biting portion 4 has a conical shape with the apex angle of the tip in the range of 26 degrees to 29 degrees.

  If α is smaller than 26 degrees, the conical shape of the biting portion 4 becomes too acute and the tip is easily broken. On the other hand, if α is larger than 29 degrees, the diameter of the female screw formed on the fastened member 7 is rapidly expanded, and as a result, cracking is likely to occur in the burring. The cracking of the burring causes a harmful effect that large cutting waste may be generated.

  In FIG. 2 (A), the apex angle of the cone enveloping the top of the symmetrical male screw 53 formed in the biting portion 4 is β. β ranges from 36 degrees to 39 degrees. Although the symmetric male screw 53 is formed in about 3 to 4 ridges, the diameter gradually increases from the tip toward the body 3. The apex angle β of the envelope cone defines the rate at which this diameter increases.

  If β is smaller than 36 degrees, the enlargement ratio of the diameter of the symmetric male screw 53 is too small, and the efficiency of opening the through hole in the fastened member 7 is deteriorated. On the other hand, if the angle is larger than 39 degrees, the through hole is rapidly expanded. In addition to causing the problem that the fastening torque is excessively increased, the burring generated when the through-hole is formed suddenly increases, thereby causing cracking of the burring and generating large cutting waste. Will increase.

  When the apex angle α of the biting portion 4 and the apex angle β of the envelope cone are in the above preferable range, the biting portion 4 appropriately cuts the surface of the fastened member 7. And the through-hole formed in the to-be-fastened member 7 is expanded in a preferable state for every mountain of the symmetrical male screw 53. That is, the burring generated in the fastened member 7 when the through hole is expanded is prevented from being cracked so as to cut it.

  Further, both the advance side flank angle and the return side flank angle of the symmetric male screw 53 are 30 degrees or more, and the sectional angle of the symmetric male screw 53 is 60 degrees or more, which is a relatively dull angle. Therefore, the possibility that the symmetrical male screw 53 cuts the burring is kept low. From the above, there is little possibility that large cutting waste is generated, and even if chips are generated, only a small number of extremely small chips are generated.

  In the broken line region γ in FIG. 2B, a transition state male screw 52 is formed around the axis Y while gradually changing its angular shape. 2C1, C2, C3, and C4 are cross-sectional examples showing a cross-sectional example every 90 degrees.

  2 (C1) has the same cross section as the completely symmetrical male screw 53. FIG. Here, the angle formed by the flank surface connected to the body portion 3 is a return side flank angle, and the angle formed by the flank surface connected to the biting portion 4 is an advance side flank angle. From this point, the cross section is as shown in FIG. The advancing flank angle (lower in the drawing) is unchanged, but the return flank angle (upper drawing) has an acute angle at the tip. This is equal to the return side flank angle of the asymmetric male screw 51. However, the base of the return flank angle is equal to the return flank angle of the symmetrical male screw 53.

  2 (C3) to (C4) are the cross-sectional angles of the male screw when traveling in the direction of the body part 3 by 180 degrees to 360 degrees. That is, the leading flank angle is unchanged, but the base of the return flank angle is reduced. In FIG. 4C4, the symmetric male screw 51 has the same cross-sectional shape.

  3A is a cross-sectional view of the asymmetric male screw 51, and FIG. 3B is a cross-sectional view of the symmetric male screw 53. The asymmetric male screw 51 is formed in the body 3. In FIG. 3B, a plane that passes through the vertex of the symmetric male screw 53 and is orthogonal to the central axis of the trunk is defined as an orthogonal plane. The angle formed by the orthogonal surface and the return flank surface 53b is referred to as a return flank angle θa2, and the angle formed by the orthogonal surface and the advance flank surface 53a is referred to as an advance flank angle θa1. Both the advance side flank angle θa1 and the return side flank angle θa2 are 30 degrees or more.

  In FIG. 3A, a plane that passes through the apex of the asymmetric male screw 51 and is orthogonal to the central axis of the trunk is defined as an orthogonal plane. The angle formed by the orthogonal surface and the return flank surface 51b is referred to as a return flank angle θb2, and the angle formed by the orthogonal surface and the advance flank surface 51a is referred to as an advance flank angle θb1. The advance flank angle θb1 is 30 degrees or more, while the return flank angle θb2 is 10 degrees or less.

  The tapping screw 1 according to the present invention, which is suitable for fastening relatively thin plates, has a male cylinder 53 having a parallel and cylindrical shape, having a substantially symmetrical and blunt angle male screw 53 in an inclined biting portion 4. Has a male screw 51 which is asymmetric and has a sharp corner. The substantially symmetric male screw 53 provided in the biting portion 4 mainly plays a role of cutting and forming the female screw on the fastened member 7. On the other hand, the asymmetric male screw 51 provided in the body 3 mainly plays a role of maintaining the fastening against the return pressure from the fastened member 7, that is, preventing it from coming off.

  After making a small hole or dent on the surface of the fastened portion 7 at the tip of the acute bite portion 4, the hole is gradually enlarged by the substantially symmetrical male screw 53 provided at the inclination of the bite portion 4. . Although burring occurs at this time, it grows gradually with the expansion of the hole, so that there is an effect that there is little possibility of being cut into large cutting waste. Further, since the cross-sectional angle (advance side flank angle θa1 + return side flank angle θa2) of the substantially symmetric male screw 53 is 60 degrees or more and a relatively dull angle, there is a possibility that the burring is cut to generate large cutting waste. There is an effect that there is little.

  After the biting portion 4 passes through the fastened portion 7, the asymmetric male screw 51 provided on the trunk portion 3 engages with the female screw formed on the fastened member 7. After the fastening operation is completed, a return pressure is applied to the return-side flank surface 51b of the asymmetric male screw 51. Further, from the return-side flank surface 51b, the female screw formed on the fastened member 7 and the surface of the face of the fastened member 7 on which the biting portion 4 projects (in FIG. 1A) Pressure returns to the lower surface). Since the return-side flank surface 51b, the female screw, and the surface of the fastened member 7 resist the return pressure, the fastening of the tapping screw 1 and the fastened member 7 is maintained.

  Here, since the return-side flank angle θb2 is as small as 10 degrees or less, the return-side flank surface 51b is a surface close to a surface orthogonal to the axis Y of the tapping screw 1. This has an effect that the return pressure applied from the return side flank surface 51b to the surface of the male screw and the fastened member 7 is dispersed without being concentrated in the vicinity of the axis Y. As a result, the burden on the surfaces of the male screw and the fastened member 7 is reduced, and there is an effect that the thin plate-like fastened member 7 is not distorted or fatigued. Further, by dispersing the stress to the fastened member 7, there is an effect of preventing the deformation of the member and improving the holding force.

  In the embodiment of the tapping screw 1 of the present invention, the transition state male screw 52 is interposed between the symmetric male screw 53 and the asymmetric male screw 51, and the shape is gradually changed. However, the present invention is not limited to this. For example, the height of the crest of the symmetric male screw 53 is gradually lowered, and the height of the crest of the asymmetric male screw 51 formed at a lower height is accordingly accompanied. It is good also as the asymmetrical male screw 51 which became high gradually and reached the predetermined | prescribed height in the trunk | drum 3.

  As described above, the tapping screw 1 according to the present invention forms a small recess even if the prepared member 7 is not previously drilled. Next, the hole is gradually enlarged by the symmetrical male screw 53 having a cross-sectional angle of 60 degrees or more. Since the cross-sectional angle is a relatively dull angle of 60 degrees or more, there is no possibility that the burring generated as the hole expands is cut. Thereby, there exists an effect which prevents generation | occurrence | production of a big cutting waste.

  When the body portion 3 of the tapping screw 1 of the present invention reaches the fastened member 7 by the fastening operation, the flank surface having the return side flank angle θb2 of the male screw 51 having an asymmetrical cross section is 10 degrees or less returns the return pressure. Maintain fastening while dispersing. Thereby, there exists an effect by which the fatigue deterioration of the to-be-fastened member 7 is reduced. Further, by dispersing the stress to the fastened member, there is an effect of preventing the deformation of the member and improving the holding force.

  FIG. 4A shows a second embodiment of the tapping screw of the present invention. The tapping screw according to the second embodiment of the present invention is obtained by applying an adhesive material 6 to the biting part 4 and the body part 3 of the tapping screw 1 according to the first embodiment. The part to be applied is the entire region of the biting part 4 and the entire region of the body part 3 or a part of the part connected to the biting part 4.

  In the tapping screw 1, it is applied to the entire region that penetrates the fastened portion 7, and the region connected to the region may be applied to a width of 1 cm (FIG. 4C). Thus, if about 1 cm extra is applied, even if the region of the body 3 that penetrates the fastened member 7 becomes longer due to the difference in the thickness of the filler 9, the region where the adhesive 6 is not applied There is no risk of piercing through. Thereby, fall of a chip can be prevented reliably. In short, the adhesive material 9 may be applied by about 1 cm longer than the length assumed to penetrate the fastened member 7.

  As described above, when the adhesive material 6 is applied from the biting portion 4 to the body portion 3, even if swarf is generated at the time of forming the female screw, it is blocked by the adhesive material 6 and partly adsorbed. Can be prevented. Further, as described above, since large chips are difficult to be generated due to the effect of the symmetrical male screw 53 provided in the biting portion 4, there is little possibility that the chips are so large that they cannot be adsorbed to the adhesive material 6.

  FIG. 4B is a cross-sectional view of the application region of the adhesive material 6 of the tapping screw 1 which is an example of the second embodiment of the present invention. The adhesive material 6 is coated with a relatively thin top portion of the male screw and a thick valley portion. If it does in this way, the space which adsorb | sucks much chips in this trough part can be ensured, and there exists an effect which can further reduce the possibility of chip fall.

  FIG. 4C is an example in which the fastening member 7 of the tapping screw 1 which is an example of the second embodiment of the present invention is fastened. FIG. 4D is an enlarged sectional view of the fastened member 7. As shown in the figure, the pressure-sensitive adhesive 6 applied to the tapping screw 1 has an effect that the pressure-sensitive adhesive material 6 peeled by fastening fills a gap where a gap is generated between the valley of the tapping screw and the fastened member 7. .

  In the second embodiment of the present invention, the adhesive material applied from the conical bite portion 4 to the cylindrical body portion 3 also has the following effects. When the conical shape of the biting portion 4 gradually enlarges the hole diameter of the fastened member 7, the surface of the applied adhesive 6 is efficiently peeled off and accumulated on the fastened member 7. This has the effect of efficiently filling the gap between the hole of the fastened member 7 and the valley between the male screws 51 provided in the body 3.

  As the adhesive material 6, if it is a solvent-type adhesive material, there are rubber-based, acrylic-based, and silicone-based materials. As the emulsifying adhesive material, there is an acrylic type. As the hot melt type adhesive material, there is a SIS system. As the liquid curable adhesive material, there is an acrylic type.

  In terms of low environmental burden and low cost, emulsified acrylic adhesive materials are preferred. The emulsification type acrylic resin pressure-sensitive adhesive can be applied to the tapping screw. Application may be by dipping. After application, the surface adhesion decreases by drying. However, when pressure is applied by the fastening action, chips can be adsorbed. Further, as the adhesive material 6, Tuck N Ace (product name of Nanbu Seisakusho Co., Ltd.) may be applied.

  FIG. 5 is a view showing a third embodiment of the tapping screw 1 of the present invention, and is a front view when the washer 10 is mounted on the tapping screw according to the present invention. When the washer 10 is attached, there is an effect that pressure due to fastening can be prevented from being concentrated on a part of the waterproof sheet 8.

DESCRIPTION OF SYMBOLS 1 ... Tapping screw, Y ... Axis of tapping screw 1, 2 ... Head, 3 ... Body,
4 ... bite portion, α ... bite portion apex angle, β ... bite portion male screw envelope apex angle,
5 ... male screw, 51 ... asymmetric male screw, 51a ... advancing flank surface of asymmetric male screw,
51b: Return-side flank surface of the asymmetric male screw, 52: Transition state male screw,
53 ... Symmetrical male screw, 53a ... Advance side flank surface of the symmetrical male screw,
53b: Return side flank surface of symmetrical male screw, 6 ... Adhesive material, 7 ... Fastened member,
8 ... waterproof sheet, 9 ... filler.

Claims (6)

A tapping screw having a head at one end of a cylindrical body, a bite at the other end, and a male screw formed in a spiral from the bite to the body, the bite being The tip has a conical shape with an apex angle in the range of 26 to 29 degrees, and the surface of the biting portion is provided with three or more symmetrically shaped male screws, and the trunk portion has a return smaller than the advancing flank angle. A male screw having an asymmetrical cross section with a side flank angle is provided, and a part of the body portion is covered with an adhesive material from the leading end of the biting portion, and when the fastening to the fastening member and the hole diameter is enlarged, A tapping screw having a structure in which a surface is peeled off, and the peeled adhesive material fills a gap formed between a valley portion of the screw and the member to be fastened.   2. The tapping screw according to claim 1, wherein a cross-sectional angle of the male screw having the symmetric cross section is 60 degrees or more, and a cross-sectional angle of the male screw having the asymmetric cross section is 40 degrees or less. .   The tapping screw according to claim 2, wherein a return side flank angle of the male screw having the asymmetrical cross section is 10 degrees or less.   4. The tapping screw according to claim 1, wherein a part where the tapping screw penetrates a non-fastened article and a part of a region connected to the part that penetrates are made of the adhesive material. A tapping screw characterized by being coated.   5. The tapping screw according to claim 1, wherein the adhesive material is an emulsified acrylic resin adhesive material.   6. The tapping screw according to any one of claims 1, 2, 3, 4, and 5, further comprising a washer that engages with the head.

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