Watertight bolt attachment structure for plate-shaped metal member

Abstract

The present invention is a waterproof mounting structure for a bolt to a plate-shaped metal member. A crimped bolt is used as the bolt, with an unthreaded portion 25 between the upper end of the male thread and the bearing surface of the bolt head being thicker than the effective diameter of the male thread 22. By inserting this crimped bolt into a pilot hole in a plate-shaped metal member and crimping it, the metal on the periphery of the pilot hole is plastically deformed toward the unthreaded portion 25, and comes into close contact with the unthreaded portion 25 to provide a waterproof structure. In addition, a sealant may be applied to the bearing surface of the crimped bolt, so that the sealant flows between the bolt and the periphery of the pilot hole in the plate-shaped metal member during crimping, providing a waterproof structure.

Description

[Technical field]

[0001] The present invention relates to a waterproof mounting structure for a bolt to a plate-shaped metal member. [Background technology]

[0002] In order to attach a roof rail to a roof panel that constitutes the roof of an automobile, a plate-shaped metal member called a roof rail bracket is used. As shown in Patent Document 1, a bolt is attached to the roof rail bracket, and the roof rail bracket is fixed to the roof panel by using this bolt.

[0003] Because this bolt penetrates the roof panel, if there is a gap between the pilot hole in the roof rail bracket and the bolt, rainwater that falls on the roof rail bracket may run down the bolt shaft and seep into the room. Therefore, conventionally, a bolt with a seal washer has been used for this bolt, and a water-stopping structure has been adopted in which the bolt with the seal washer is inserted from the ceiling side and the nut is screwed in from the inside of the room to make the seal washer adhere to the roof rail bracket, preventing rainwater from seeping in.

[0004] However, when fitting a nut onto the bolt with a seal washer that has penetrated the roof panel from inside the vehicle, the torque applied to the nut causes the bolt with the seal washer to spin freely, resulting in poor workability. In addition, because the bolt with the seal washer is made up of two members, the bolt body and the seal washer, there is a problem that the cost of the bolt increases. The above-mentioned problems are not limited to roof panel brackets, but can also occur when attaching bolts to plate-shaped metal members such as roof panels, dash panels, floor panels, battery packs, and door panels that require waterproofing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-297841 A Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT INVETION It is an object of the present invention to solve the above-mentioned problems of the conventional art and to provide a waterproof mounting structure for a bolt to a plate-shaped metal member which has excellent waterproofing properties and workability and is low cost. [Means for solving the problem]

[0007] The invention of claim 1, which has been made to solve the above problems, is a waterproof mounting structure for a bolt to a plate-shaped metal member, the bolt being a crimped bolt inserted into a pilot hole in the plate-shaped metal member and crimped. This crimped bolt has an unthreaded portion between the upper end of the male thread formed in the bolt shank and the head seat of the bolt that is made thicker than the effective diameter of the male thread, and the metal on the periphery of the pilot hole in the plate-shaped metal member plastically deforms toward the unthreaded portion when crimped, and comes into close contact with the unthreaded portion to provide a waterproof structure. It is characterized by the above.

[0008] In addition, the invention of claim 2, which was made to solve the above-mentioned problems, is a waterproof mounting structure for a bolt to a plate-shaped metal member, wherein the bolt is a crimped bolt that is inserted into a pilot hole in the plate-shaped metal member and crimped, and by applying a sealant to the seating surface of the bolt, the sealant flows into the gap between the peripheral portion of the pilot hole in the plate-shaped metal member and the bolt when crimped, thereby providing a waterproof structure. Effect of the Invention

[0009] According to the waterproof mounting structure for a bolt to a plate-shaped metal member of the present invention, a crimp bolt is inserted into a pilot hole of the plate-shaped metal member and crimped as a bolt to fix the plate-shaped metal member, so that the crimp bolt does not rotate relative to the plate-shaped metal member. Therefore, the crimp bolt does not spin freely when the nut is tightened, and the workability of tightening the nut can be improved.

[0010] Furthermore, according to the waterproof mounting structure for plate-shaped metal members of the present invention, there is no need for a bolt with a sealing washer consisting of two components as in the conventional method, and the waterproof structure can be achieved with a single crimp bolt, making it possible to reduce the cost of the bolt. [Brief description of the drawings]

[0011] [Figure 1] 2 is a cross-sectional view showing the overall structure in a state in which a roof rail bracket, which is a plate-shaped metal member, is fixed to a roof panel. FIG. [Diagram 2] FIG. 4 is an enlarged front view of a crimp bolt used in the first embodiment. [Diagram 3] 1 is a cross-sectional view showing a state in which a caulking bolt according to a first embodiment is inserted into a prepared hole in a roof rail bracket which is a plate-shaped metal member. [Figure 4] 1 is a cross-sectional view showing a state in which a crimping bolt according to a first embodiment is inserted into a prepared hole in a roof rail bracket which is a plate-shaped metal member and crimped. [Diagram 5] FIG. 11 is an enlarged front view of a crimp bolt used in the second embodiment. [Figure 6] FIG. 4 is a cross-sectional view showing a state in which a crimping bolt according to a second embodiment is inserted into a prepared hole in a roof rail bracket, which is a plate-shaped metal member, and crimped. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (First embodiment) A first embodiment of the present invention will be described below. In the first and second embodiments shown below, a waterproof mounting structure for a bolt to a roof rail bracket, which is a plate metal member, will be described. The roof rail bracket is fixed to a roof panel using this bolt. However, the plate metal member in the present invention is not limited to the roof rail bracket, and can be widely applied to roof panels, dash panels, floor panels, battery packs, door panels, etc., which require waterproofing.

[0013] First, Figure 1 shows the overall structure of a roof rail bracket fixed to a roof panel. In Figure 1, 10 is a roof rail bracket which is a plate-shaped metal member, and 11 is the roof panel of the automobile. 12 is a crimp bolt which is a bolt attached to the roof rail bracket 10, and 13 is a nut which is screwed onto the crimp bolt 12 from the inside of the vehicle. Also, 14 is a sponge placed between the roof rail bracket 10 and the roof panel 11. As will be explained below, the crimp bolt 12 is inserted into a prepared hole in the roof rail bracket 10 and crimped to waterproof the bracket, and then the crimp bolt 12 is inserted into the roof panel 11 and fixed by the nut 13.

[0014] Fig. 2 is an enlarged front view of the crimp bolt 12 used in the first embodiment. In Fig. 2, 20 is the head of the bolt, 21 is the shank of the bolt, and 22 is a male thread formed on the shank 21. 23 is the bearing surface of the head 20, and a star-shaped protrusion 24 is formed around the entire periphery of the bearing surface 23. This protrusion 24 has the function of biting into the roof rail bracket 10 when the crimp bolt 12 is inserted into and crimped into the roof rail bracket 10, which is a plate-shaped metal member, and preventing the bolt from spinning freely.

[0015] An unthreaded portion 25 is formed between the upper end of the male thread 22 of the crimp bolt 12 and the bearing surface 23. The diameter of this unthreaded portion 25 is formed to be thicker than that of a normal crimp bolt. Specifically, the diameter of the unthreaded portion 25 is larger than the effective diameter of the male thread 22 and smaller than the outer diameter of the male thread 22. For example, in the case of the M8 size, the JIS specifies that the outer diameter of the male thread is 8.000 mm, the root diameter is 6.647 mm, and the effective diameter is 7.188 mm, so the diameter of the unthreaded portion 25 is set to be larger than 7.188 mm and smaller than 8.000 mm.

[0016] 3 is a cross-sectional view showing the state in which this crimp bolt 12 has been inserted into a prepared hole in a roof rail bracket 10, which is a plate-shaped metal member. Reference numeral 30 denotes a die, which has a central hole 31 through which the shaft 21 of the crimp bolt 12 is inserted. The upper surface 32 of the die 30 is flat, on which the roof rail bracket 10 is placed, and a narrow annular protrusion 33 is formed in the center of the upper surface 32 of the die 30. The crimp bolt 12 inserted into the prepared hole is crimped by applying pressure from above with a punch (not shown).

[0017] This pressure causes the convex portion 24 formed on the seat surface 23 of the crimp bolt 12 to bite into the upper surface of the roof rail bracket 10, firmly fixing the crimp bolt 12. At the same time, the annular protrusion 33 of the die 30 bites into the peripheral portion of the pilot hole in the roof rail bracket 10, plastically deforming the metal of that portion toward the unthreaded portion 25 of the crimp bolt 12 and bringing it into close contact with the unthreaded portion 25. As described above, the unthreaded portion 25 has a larger diameter than usual, which makes it easier to bring the metal of the peripheral portion of the pilot hole into close contact with the unthreaded portion 25 without any gaps, as shown in Figure 4. Data on the watertight performance and idling torque will be shown in the examples described later.

[0018] As described above, by using the die 30 with the annular projection 33 to fix the crimp bolt 12 with the thickened unthreaded portion 25 to the roof rail bracket 10, which is a plate-shaped metal member, the unthreaded portion 25 can prevent further infiltration even if rainwater infiltrates between the seat surface 23 of the crimp bolt 12 and the upper surface of the roof rail bracket 10, and an excellent water-stopping effect can be obtained. In addition, since the crimp bolt 12 is firmly fixed to the roof rail bracket 10, the crimp bolt 12 does not spin freely when the nut 13 shown in FIG. 1 is tightened, and the workability of fastening can be improved. Furthermore, unlike the conventional bolt with a seal washer, only the crimp bolt 12 is used, and therefore the cost of the bolt can be reduced.

[0019] Second embodiment Next, a second embodiment of the present invention will be described. The second embodiment is similar to the first embodiment in that the crimping bolt 12 is inserted into a prepared hole in the roof rail bracket 10, which is a plate-shaped metal member, and then crimped and fixed. However, as shown in Fig. 5, a sealant 40 is applied to the bearing surface 23 to which pressure is applied when the crimping bolt 12 is crimped. As the sealant 40, an epoxy resin-based thermoplastic sealant that is often used in the technical field of bolts and nuts can be used, but the material of the sealant is not necessarily limited to this.

[0020] When the crimp bolt 12 with the sealant 40 applied to the seating surface 23 is inserted into the prepared hole of the roof rail bracket 10, which is a plate-shaped metal member, and crimped, the sealant 40 pushed out from the seating surface 23 flows into the unthreaded portion 25 of the crimp bolt 12 as shown in FIG. 6, and seals between the shaft portion 21 of the bolt and the prepared hole of the roof rail bracket 10. Although not shown in the figure, a part of the sealant 40 also flows to the outer periphery of the seating surface 23 during crimping, improving the sealing performance between the seating surface 23 and the plate-shaped metal member. Therefore, a water-stopping effect can be obtained as in the first embodiment. In addition, the effect of preventing idling and the effect of reducing costs can be obtained as in the first embodiment.

[0021] In the second embodiment, it is not necessarily required to make the diameter of the unthreaded portion 25 of the crimping bolt 12 larger than usual or to use a die 30 with an annular protrusion 33. However, by combining the first and second embodiments and using a crimping bolt 12 with a larger diameter unthreaded portion 25, applying a sealant 40 to its bearing surface 23, and crimping using a die 30 with an annular protrusion 33, a better water-stopping effect can be obtained. EXAMPLES

[0022] The results of evaluation experiments on the product of the present invention are shown below. A pilot hole with a diameter of 8.0 mm was drilled into a test piece with a thickness of 0.5 mm, made of the same steel plate material as the roof rail bracket, and a crimping bolt of the shape shown in Figure 1 was crimped using a die and punch. The crimping load was 100 kN. Separately, a sample was also created in which an epoxy resin-based sealant was applied to the bearing surface of the crimping bolt.

[0023] Next, a nut was fixed to the crimped bolt and the nut was rotated with a torque wrench to measure the torque at which the crimped bolt peeled off from the test piece and began to spin freely (idle torque). As a result, without sealant, the average idle torque (N=5) was 23.8N·m, and with sealant, the average idle torque (N=5) was 26.4N·m, both of which showed good results.

[0024] Next, test pieces (N=6) were placed at a depth of 30 mm in water and a water leakage test was conducted. As a result, the amount of water leakage after 24 hours was zero, both with and without the sealant. Furthermore, a test was conducted in which air was bubbled into the water, but the amount of water leakage was also zero, confirming the perfect sealing.

[0025] As described above, the waterproof mounting structure for mounting a bolt to a plate-shaped metal member of the present invention has the advantages of excellent waterproofing properties, ease of operation, and low cost, and is therefore highly practical. [Explanation of symbols]

[0026] 10. Roof rail bracket made of sheet metal 11 Roof Panel 12 Crimp bolt 13 Nut 14 Sponge 20 bolt head 21 Bolt shaft 22 Male thread 23 Seat 24 Convex 25 Unthreaded section 30 Dice 31 Center hole 32 Top side 33 Annular protrusion 40 Sealant

Claims

1. A waterproof mounting structure for a bolt to a plate-shaped metal member, The bolt is a crimp bolt that is inserted into a pilot hole of the plate-shaped metal member and crimped, This crimp bolt has an unthreaded portion between the upper end of the male thread formed on the bolt shank and the head seat of the bolt that is made thicker than the effective diameter of the male thread, A waterproof mounting structure for a bolt to a plate-shaped metal member, characterized in that the metal around the peripheral portion of the pilot hole in the plate-shaped metal member plastically deforms toward the unthreaded portion when crimped, and adheres closely to the unthreaded portion to provide a waterproof structure.

2. A waterproof mounting structure for a bolt to a plate-shaped metal member, The bolt is a crimp bolt that is inserted into a pilot hole of the plate-shaped metal member and crimped, A waterproof mounting structure for a bolt to a plate-shaped metal member, characterized in that by applying a sealant to the seating surface of the bolt, the sealant flows into the gap between the peripheral portion of the pilot hole in the plate-shaped metal member and the bolt when the bolt is crimped, thereby providing a waterproof structure.

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