JP2006177438A - Tightening method of metal plate and tapping screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent slipping of a tapping screw and obtain a sufficient tightening force without breakage of a screw thread of a screw hole formed in a metal plate when a tapping screw is screwed in the metal plate to be tightened. <P>SOLUTION: The tapping screw is equipped with a screw body 40 including a head part 42 in one end of a shaft part 41 formed in a screw thread 45, and a washer 50 mounted in the screw body 40. The washer 50 is made of rubber whose hardness is 80°-120°. The washer 50 is compressed between the head part 42 and the metal plate 60 by a tapping screw 30 to be screwed in. The play of the tapping screw 30 is prevented through friction and resilient force of the washer. The inner periphery 62 of the screw hole in the metal plate 60 is deformed toward the head part 42 side by a burring effect so as to increase screw threads. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fastening method for fastening a metal plate such as a thin steel plate in a building structure, a mechanical structure, and the like, and a tapping screw capable of suitably realizing the method.

  The tapping screw is used, for example, when a member is fastened to a relatively thin metal plate. A tapping screw is a screw that is fastened together with a hole while forming a screw thread (female screw) on the inner peripheral surface of the hole when screwed into a metal plate. For this reason, there is an advantage that a rigid and stable fastening force can be obtained by eliminating the need for a pilot hole or by closely contacting the threaded portion with the formed screw thread. It is.

  However, when the tapping screw is screwed in, for example, if an excessive fastening torque is erroneously applied, the tapping screw may further rotate after the fastening is normally performed. In this case, the screw thread of the screw hole is destroyed, and further, the rotation continues and the tapping screw is idled so that the fastening is impossible. Such tapping screw slipping due to the destruction of the female screw can be prevented by controlling the tightening torque, but the accuracy of the management must be increased, which is troublesome and allows rough operation. Without a loss of productivity.

  On the other hand, when the tapping screw is screwed into the metal plate, plastic deformation in which the metal plate protrudes in a cylindrical shape in the screwing direction occurs like burring, and the screw hole is formed longer than the thickness of the metal plate by the protruding portion. Will be. In some cases, the idling may be suppressed halfway due to the burring effect, but this causes a variation in fastening force. That is, since the protruding portion is formed by screwing the tapping screw, the burring effect for extending the screw hole cannot be expected to sufficiently prevent idling.

  Therefore, it is conceivable to prevent the idling by sandwiching a washer made of elastic rubber or the like between the tapping screw and the metal plate. If the tapping screw is screwed into the metal plate through such an elastic washer, the washer is elastically deformed and crushed, so that excessive torque is absorbed, and the tapping screw is normally fastened to prevent excessive rotation of the tapping screw. It is assumed that idling is prevented. A washer made of an elastic body such as rubber is known, for example, from Patent Document 2.

JP-A-10-220441 Japanese Patent Laid-Open No. 2001-124044

  However, the rubber washer described in the above-mentioned Patent Document 2 is used for preventing loosening to cope with the thinning of a wooden building, and is applied to a tapping screw for fastening a metal plate, which is an object of the present invention and easily causes idling. In this case, it is unclear how much the tapping screw has a function to prevent idling. What is predicted here is that the hardness of the washer is described as 40 ° to 80 ° in the same document 2, and it is feared that this hardness is insufficient to cope with the fastening force due to a large torque. Is done.

  Therefore, according to the present invention, when the tapping screw is screwed into the metal plate and fastened, the screw hole of the screw hole formed in the metal plate is not broken and the tapping screw is prevented from idling and a sufficient fastening force is obtained. It is an object of the present invention to provide a metal plate fastening method and a tapping screw that can be used.

  The method for fastening a metal plate according to the present invention is such that a tapping screw is screwed into a metal plate through an elastic member to form a screw hole in the metal plate, and the tapping screw is passed through the metal plate to Is engaged with the metal plate via the elastic member, and then the tapping screw is further rotated with a predetermined torque, thereby compressing the elastic member and deforming the inner peripheral portion of the screw hole of the metal plate to the tapping screw side. It is characterized by that.

  In the above fastening method, the tapping screw is further rotated with a predetermined torque from the state in which the head of the tapping screw is engaged with the metal plate via the elastic member, and this operation first causes compression of the elastic member. When the tapping screw receives the elastic force, idling is prevented. Further, instead of screwing the tapping screw into the metal plate, the inner peripheral portion of the screw hole of the metal plate is pulled in the direction of the head of the tapping screw, and plastic deformation occurs in the inner peripheral portion of the screw hole like burring processing. . Due to this burring effect, the head side of the tapping screw in the deformed inner periphery of the screw hole rises from the surface of the metal plate and protrudes in a cylindrical shape. Due to such deformation of the inner peripheral portion of the screw hole, the length of the screw hole increases beyond the thickness of the metal plate, and the number of screw threads increases.

  Since the burring effect is to deform the inner periphery of the screw hole toward the head side of the tapping screw, the extension effect of the screw hole can be obtained more sufficiently than simply by screwing the tapping screw. As a result, the effect of improving the fastening force can be significantly obtained.

  Next, the tapping screw according to the present invention can suitably realize the fastening method according to the present invention, and includes a screw body having a head at one end of a shaft portion on which a thread is formed, and the screw body. The washer is characterized by comprising a rubber having a hardness of 80 ° to 120 °.

  According to this tapping screw, when the screw is screwed in while forming a screw hole in the metal plate, the washer comes into contact with and engages with the metal plate, and when the screw is further screwed in, the washer is compressed by the head, so that the washer is elastic. While generating force arises, the friction accompanying this arises between a washer and a metal plate, and rotation of a washer is controlled. At this stage, the tapping screw receives a resilient force of the washer and generates a strong friction with the washer, so that the tapping screw is not easily rotated, thereby preventing the tapping screw from slipping. Further, when the tapping screw is rotated with a strong force, the washer is not compressed, and the elastic force of the washer in this state and the friction generated between the washer and the metal plate are further increased. Then, instead of screwing the tapping screw into the metal plate, the inner peripheral portion of the screw hole of the metal plate is pulled and deformed in the direction of the head of the tapping screw, and the burring effect is generated. As a result, the number of threads formed on the metal plate is increased and the fastening force is improved.

  The burring effect is effectively generated because the washer has a hardness of 80 ° to 120 °, and the hardness allows the tapping screw to be normally tightened even with a relatively rough operation. When the hardness of the washer is less than 80 °, it is too soft and the anti-spinning function does not work sufficiently, and when it exceeds 120 °, it is too hard to be compressed and hardly produces a resilience to suppress idling. In addition, the hardness of the washer is more preferably 85 ° to 110 ° within this range, and further preferably 90 ° to 100 °.

  Although the tapping screw is prevented from idling as described above, even if idling occurs due to excessive torque, the thread of the screw hole remains due to the elastic force of the washer, and the fastening force is maintained. The In addition, it is preferable that the screw thread of the shaft portion is as much as possible, that is, the pitch is as fine as possible, in order to form a large number of screw threads on the screw hole side formed with the burring effect.

  According to the present invention, when a tapping screw is screwed into a metal plate and fastened, the tapped screw is prevented from idling without being damaged, and a sufficient fastening force is obtained. There is an effect that it can be obtained.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Fig.1 (a) has shown one Embodiment of the tapping screw of this invention. The tapping screw (hereinafter simply referred to as “screw”) 30 includes a screw body 40 and a washer 50.

  The screw body 40 has a head portion 42 at one end of a shaft portion 41. A cross hole 43 into which a tightening tool such as a screwdriver is fitted is formed on the surface of the head portion 42, and a flange is formed on the back surface side. 44 is integrally formed. A screw thread (male screw) 45 is formed on the outer peripheral surface of the shaft portion 41, and a conical cone portion 46 for drilling a metal plate as a member to be fastened is formed at the tip portion. In addition, you may change the cone part 16 for drilling into the drill part 47, as shown in the screw 30 of FIG.1 (b).

  The washer 50 has a ring shape with an outer peripheral surface formed in a semicircular curved surface, and the shaft portion 41 of the screw body 40 is inserted into the hole and is in a state of being close to or in contact with the flange 44. Mounted on the main body 40. The washer 50 is desirably in a state in which it cannot rotate relative to the screw body 40. For this purpose, for example, the inner diameter of the hole of the washer 50 is made smaller than the inner diameter of the thread 45 of the shaft portion 41, and the shaft portion 41 is press-fitted. The method of screwing in is taken.

  The washer 50 is formed from rubber having a hardness of 80 ° to 120 °. Examples of rubber materials include synthetic resin rubbers such as ethylene propylene rubber (EPDM), nitrile rubber (NBR), and fluorine rubber (FKM) that are suitably used as packing materials for various hydraulic or pneumatic equipment, and natural rubber. Of these, rubber is selected, and among these, EPDM is particularly preferably used because it can sufficiently bring out the effects of the present invention in terms of characteristics such as elasticity and friction coefficient.

  Next, the fastening method by the screw 30 and the effect accompanying it will be described with reference to FIG. As shown in FIG. 2A, the screwdriver 30 is screwed into the metal plate 60 until the driver D is fitted into the cross hole 43 and the washer 50 is brought into contact with and engaged with the surface of the metal plate 60. In the metal plate 60, a pilot hole is first formed by the conical portion 46, and then the screw thread 45 reaches the pilot hole and is screwed therein, whereby the diameter of the pilot hole is increased and a screw thread (female screw) is formed on the inner peripheral surface thereof. Is formed and the screw hole 61 is drilled.

  When the screw 30 is further screwed in, the washer 50 is compressed by the head 42 and friction is generated between the washer 50 and the head 42 receives the elastic force of the washer 50, whereby the rotation is restricted. Thus, the idling of the screw 30 is prevented. In FIG. 2, the flange 44 of the head 42 is slightly separated from the washer 50, but actually the flange 44 is pressed against the washer 50.

  When the screw 30 is further rotated with a strong force, the washer 50 is not compressed, and instead of the screw 30 being screwed into the metal plate 60, the screw hole inner peripheral portion 62 of the metal plate 60 is directed toward the head 42 of the screw 30. As shown in FIG. 2B, plastic deformation such as burring occurs in the inner peripheral portion 62 of the screw hole. Due to this burring effect, the screw hole inner peripheral portion 62 bites into the washer 50 and the head 42 side rises and protrudes in a cylindrical shape, whereby the length of the screw hole 61 increases beyond the thickness of the metal plate 60, The number of increases.

  According to the screw 30, the idling of the screw 30 is effectively prevented by the elastic force of the compressed washer 50 according to the hardness held. Further, the screw hole inner peripheral portion 62 protrudes toward the head portion 42 due to the burring effect and the number of screw threads is increased, so that the fastening force can be improved. Since the burring effect is to deform the screw hole inner peripheral portion 62 toward the head 42 side of the screw 30, the extension effect of the screw hole 61 is the same as the head 42 obtained by screwing the screw 30 into the metal plate 60 first. Can be obtained more sufficiently than the burring effect on the opposite side.

  The screw 30 is preferably used for fastening a metal plate in a building structure, a mechanical structure, or the like, and is used as, for example, a means for fixing a roof material of a roof portion of a house shown in FIG.

  In the roof portion 20 of FIG. 3, a ventilation rafter 25 is fixed on a roof base material 21 in which a field plate 23 is fixed on a roof rafter 22, and between adjacent roof rafters 22. A plate-like heat insulating material 24 is disposed. A metal sandwich heat insulating panel (hereinafter referred to as a heat insulating panel) 26 is provided on the ventilation rafter 25.

  The heat insulation panel 26 has a plate-like heat insulating material such as a polystyrene board as a core material, and the heat insulating material is sandwiched between thin plate-like metal plates. As the metal plate, for example, a general steel plate or a galvalume steel plate is used, and is attached to the front and back surfaces of the heat insulating material by means such as adhesion. The heat insulation panel 26 is fixed to the ventilation rafter 25 by a fastener such as a countersunk screw 30 that penetrates from the outside and is screwed into the ventilation rafter 25.

  A roof ventilation layer 27 is provided between the base plate 23 and the heat insulation panel 26 using the ventilation rafter 25 as a spacer, and the ridge side of the roof ventilation layer 27 is connected to a ridge ventilation port (not shown) provided in the ridge. Open to the outside.

  An asphalt roofing 28 is laid as a waterproof sheet on the heat insulation panel 26, and a large number of roofing materials 29 are spread thereon, whereby the roof portion 20 extending from the roof base material 21 to the roofing material 29 is formed. Yes.

  For the roof material 29, for example, a metal tile made of a metal plate rich in corrosion resistance such as tin (galvanized steel plate) is used, and heat insulation is performed by the screw 30 that penetrates from the outside and is screwed into the upper metal plate of the heat insulation panel 26. It is fixed to the panel 26.

  FIG. 4 shows a state in which the roof material 29 is fastened to the heat insulating panel. In this case, the roof material 29 corresponds to the metal plate 60 shown in FIG. In FIG. 4, 26a is a heat insulating material of the heat insulating panel 26, and 26b is an upper metal plate sandwiching the heat insulating material 26a. The screw 30 is screwed in while drilling the roof material 29, the asphalt roofing 28 and the metal plate 26b, and at least the inner peripheral portion of the screw hole of the roof material 29 rises upward and protrudes due to the burring effect described above. The metal plate 26b of the heat insulation panel 26 hardly protrudes upward in the screw hole inner periphery due to the elasticity of the asphalt roofing 28, but it protrudes in some cases.

  When the roofing material 29 is fixed to the heat insulating panel 26 with a general tapping screw, the tapping screw may idle with respect to the roofing material 29 or the metal plate 26b. In particular, the heat insulating panel 26 has a thin metal plate 26b. Since the core material is the heat insulating material 26a which does not have any screw fastening force, the roof material 29 is required to be securely fixed to the metal plate 26b. Therefore, if the screw 30 according to the present invention is fixed as shown in FIG. 4, the screw 30 is prevented from idling and the roof material 29 can be fixed to the heat insulating panel 26 with a high fastening force.

Next, examples of the present invention will be described.
(1) Tensile test to verify the fastening force of the tapping screw (a) Washer hardness 90 °
As shown in FIG. 5, a U-shaped jig 70 is attached to a screw body (M4 × 20 mm) using a screw 30 of the present invention in which a washer made of EPDM and having a hardness of 90 ° is attached. The fastening torque was set to 1.96 N · m and fixed to the heat insulating panel 26. The heat insulation panel 26 made by Dow Chemical Co., Ltd. having a thickness of 35 mm: Styrofoam was used as the heat insulation material 26a, and a metal plate 26b was bonded to both sides as a metal plate 26b with a galbarium steel plate having a thickness of 0.35 mm. Five such test specimens were prepared (test specimens Nos. 1 to 5), and for these specimens, the heat insulation panel was fixed to a tensile tester, and the pin 71 passed through the jig was pulled at a speed of 10 mm / min. The maximum load until the screw was removed or broken was measured.

(B) Washer hardness 80 °
A tensile test was performed in the same manner as in the above (a) except that the screw washer was changed to one having a hardness of 80 °.

(C) No washer A tensile test was performed in the same manner as in the above (a) except that no washer was attached and only the screw body was used.

Table 1 shows the results of the tensile tests (a) to (c).
According to Table 1, it can be seen that the screw fitted with the washer exhibits a strong and stable fastening force, which is due to the hardness of the washer being 80 ° and 90 °, and the effect of the present invention. Has been demonstrated. When the hardness of the washer is less than 80 °, the average maximum load is sufficiently predicted to be 60 kgf or less. Therefore, it was confirmed that the washer needs to have a hardness of 80 ° or more. On the other hand, in the case of no washer, idling of the screw was recognized, and therefore, it was confirmed that the fastening force was varied and extremely low and impractical.

(2) Pseudo Wind Resistance Test As shown in FIGS. 3 and 4, the screw of the present invention is useful as a fastener for fixing a roof material to a heat insulating panel with a heat insulating material sandwiched between metal plates. Therefore, the roof material is fixed to the heat insulation panel in a state in accordance with the screw according to the present invention, and a pseudo wind resistance test is performed as follows to check whether the roof material is peeled off by the influence of wind. It was.

In accordance with the “Guideline for Wind Resistance Design of Roofs” issued by the Housing Exterior Technical Center, test specimens were prepared as follows.
・ Roofing material: Color iron plate press tile roof (made by Chiyoda Steel)
t0.35 × W234 × L1886 (mm)
Working width: 1818 x Working length 182 (mm)
・ Insulation panel: t35 × W1200 × L2400 (mm) manufactured by Dow Chemical Industries: Styro
Bonded galbarium steel sheet of t0.35mm on both sides of the foam ・ Tapping screw: The product of the present invention M4 × 20mm, with a 90 ° hardness washer
Number of use: 7 The roof material was fixed to the heat insulation panel with the tapping screw in the same manner as in actual construction.

・ Measurement of lifting force The lifting force for lifting the roofing material was calculated from the required wind pressure by the calculation formula shown in the Ministry of Construction Notification. In the description example of the guideline, the wind pressure is −124 to −231 kg / m ² , and the lifting force per working area in the general-purpose construction method (3 sheets / m ² ) is 42 to 77 kg / sheet. In this test, 80 kg / sheet (240 kg / m ² ) was adopted in consideration of the maximum value.

・ Applying device and applying method As an applying position for lifting the roofing material, the roofing material is sandwiched between two steel pipes, the jig held on these steel pipes is pulled up with wires, and the roofing material is pulled up evenly with respect to the working surface. A device was used. With this force device, the operation of “lifting → releasing” on the roofing material was repeated 200 times, with 80 kg being repeatedly set as the load. This is because the main cause of the scattering of the roof material due to the wind pressure is the negative pressure that repeatedly acts during strong winds, and this wind condition is given to the roof material in a simulated manner in this test as well.

-Test results It was visually observed that no trouble occurred in the fastening portion of the screw and that the screw did not come off or float up during repeated application of force as described above. As a result, it was confirmed that no abnormality was observed even after repeated application of 200 times, and that the fastening force by the screw was strong and stable. Further, after that, a load was applied up to 200 kg / sheet, but no abnormality was observed. From these results, it was found that the screw of the present invention is extremely suitable as a fastener for fixing a metal roofing material to the heat insulating panel as described above.

It is a side view which shows the tapping screw of this invention, Comprising: (a) is the one Embodiment, (b) shows the example of a change. (A) is a side view showing a state in which the tapping screw of one embodiment is screwed into the metal plate until the washer engages with the metal plate, and (b) is a cross-sectional view showing a state in which idling is prevented by further screwing. . It is sectional drawing of the roof structure to which the tapping screw of one Embodiment is applied. It is sectional drawing which shows the state which fixed the roof material of the roof structure shown in FIG. 3 to the heat insulation panel with the screw of one Embodiment. It is a perspective view of the test body produced with the tension test method of an Example.

Explanation of symbols

30 ... Tapping screw, 40 ... Screw body, 41 ... Shaft, 42 ... Head,
45 ... Tapping screw thread, 50 ... Washer (elastic member), 60 ... Metal plate,
61 ... Screw hole of metal plate, 62 ... Inner periphery of screw hole of metal plate.

Claims (2)

  By screwing the tapping screw into the metal plate through the elastic member, the tapping screw penetrates the metal plate while forming a screw hole in the metal plate, and the head of the tapping screw is attached to the metal plate through the elastic member. After the engagement, the tapping screw is further rotated with a predetermined torque to compress the elastic member and to deform the inner peripheral portion of the screw hole of the metal plate to the tapping screw side. Method. A tapping screw that is screwed through the metal plate while forming a screw hole in the metal plate, and has a screw body having a head at one end of a shaft portion on which a screw thread is formed, and is attached to the screw body. A tapping screw, wherein the washer is made of rubber having a hardness of 80 ° to 120 °.

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