JP7493997B2 - Nut attachment structure near the welded part - Google Patents

Description

The present invention relates to a nut attachment structure near a welded portion, and in particular to a nut attachment structure near a welded portion that can suppress deformation of the threaded portion due to heat during welding.

As shown in FIG. 1(a), a known thread structure near a welded portion is one in which a tap is applied directly to plate a to form a screw hole b, and the edge of plate a with the screw hole b is welded to a workpiece c. d is a weld bead. As shown in FIG. 1(b), a bolt e is screwed into the screw hole b of plate a welded to the workpiece c in this way, and a workpiece f is sandwiched between the bolt e and plate a. In this structure, when plate a with the screw hole b is welded to the workpiece c, the welding heat is likely to cause deformation of the screw hole b, making it difficult to properly screw in the bolt e. In this case, it is necessary to correct the screw hole b by retapping.

However, when the workpiece c is a part that requires sealing, such as an axle case, as shown in FIG. 1(b), it is not possible to drill a hole in the workpiece c below the screw hole b, so the tapping tool cannot be screwed all the way into the screw hole b, and a huge amount of work is required to correct the screw hole by retapping. On the other hand, it is possible to suppress thermal deformation of the screw hole b by setting the distance L1 between the edge of the plate a, which becomes the welded part (weld bead d) shown in FIG. 1(a), and the screw hole b large and separating the screw hole b from the heat input part of the weld, but there are cases in which it is not possible to increase the distance L1 between the edge of the plate a and the screw hole b due to the shape of the workpiece c (e.g., an axle case) shown in FIG. 1(b) and the constraints of the surrounding parts g.

As another nut mounting structure near the welded portion, as shown in FIG. 2(a), a bolt insertion hole i is formed through an inverted U-shaped plate h, a nut j is welded to the inside of the plate h in accordance with the position of the bolt insertion hole i, and the inverted U-shaped plate h with the nut j is welded to the mounting member (axle case, etc.) c. However, in this structure, the nut j overlaps the inverted U-shaped plate h, so the height H1 of the inverted U-shaped plate h is increased by the height (thickness) of the nut j, and in some cases this may not be possible due to restrictions on the height layout of the peripheral parts g (see FIG. 1(b)) of the mounting member (axle case, etc.) c.

As another nut mounting structure near the welded part, as shown in Figure 2 (b), a cap nut is known in which a nut n is housed inside an inverted U-shaped bracket m with a bolt insertion hole k formed therethrough, and the bracket m is welded to the mounting member (axle case, etc.) c. However, even in the case of this cap nut, the nut n overlaps the inverted U-shaped bracket m, so the height H2 of the inverted U-shaped bracket m increases by the height of the nut n, and in some cases this does not work due to restrictions on the height layout of the peripheral parts g (see Figure 1 (b)) of the mounting member (axle case, etc.) c.

As another possible nut mounting structure near the welded portion, as shown in Figure 2(c), a bolt insertion hole p is formed through the member c to be mounted, a nut q is welded to the inside surface of the member c to match the position of the bolt insertion hole p, and a bolt (not shown) is screwed into the nut q from the outside of the member c to be mounted. However, since the member c to be mounted needs to have a bolt insertion hole p, this structure cannot be applied when the member c to be mounted is a part that requires oil sealing, such as an axle case.

Patent Document 1 also discloses a special nut with an annular groove formed around the screw hole on the bottom surface of the nut, which is used to suppress deformation of the screw hole due to welding heat when the nut is welded to the plate to which it is attached. This special nut is welded and fixed to the plate to which it is attached, aligned with the position of the bolt insertion hole formed through the plate to which it is attached. During this welding, the welding heat escapes from the annular groove formed on the bottom surface of the nut, suppressing thermal deformation of the screw hole.

However, if the plate being attached is a part that requires oil sealing, such as an axle case, it is not possible to drill holes in the plate, and so this type of nut attachment structure is not viable. Also, in this nut attachment structure, the tightening torque of the bolt screwed into the screw hole is received by the welded part, so the weld bead needs to be made larger to increase the tightening torque, which increases the amount of heat input, and even if heat is dissipated from the annular groove, there is a possibility that thermal deformation will occur in the screw hole.

Japanese Patent Application Laid-Open No. 7-27123

The object of the present invention, which was devised in consideration of the above circumstances, is to provide a nut mounting structure near a welded part that can suppress deformation of the threaded part due to welding heat even when the distance from the welded part to the nut is short, can reduce the mounting space in the height direction of the nut as much as possible, and can obtain a sufficient tightening torque.

In order to achieve the above-mentioned object, the present invention provides a nut mounting structure near a welded portion comprising a mounting plate having a bent portion on its edge, a weld bead formed by welding the bent portion of the mounting plate to the member to be mounted, a gap formed between the member to be mounted and the portion of the mounting plate other than the bent portion, a polygonal or elongated mounting hole formed through the portion of the mounting plate other than the bent portion, a nut formed in the same shape as the mounting hole and non-rotatably accommodated in the mounting hole with a clearance, and a flange extending from the nut into the gap, wherein the flange of the nut accommodated in the mounting hole of the mounting plate is spot welded or brazed to the mounting plate .

In the nut mounting structure near a welded portion according to the present invention, the thickness of the nut received in the mounting hole of the mounting plate may be equal to or greater than the thickness of the mounting plate.

In the nut mounting structure near the welded portion according to the present invention, the bolt may be screwed into the nut, and the fastened member may be sandwiched between the bolt and the nut.

The nut attachment structure near a welded portion according to the present invention has the following advantages.
(1) The nut is accommodated in the mounting hole of the mounting plate with a clearance between them, and this clearance acts as an insulating air layer when the bent portion of the mounting plate is welded to the workpiece. Therefore, even if the distance from the welded portion to the nut is short, deformation of the screw hole due to welding heat can be suppressed, and retapping is not required.
(2) Since the nut is housed in the mounting hole of the mounting plate, the height (thickness) dimension of the nut is absorbed by the plate thickness of the mounting plate, and the height (thickness) dimension of the nut can be reduced. Therefore, the layout constraints of the peripheral parts of the mounting member in the height direction of the nut are relaxed.
(3) The mounting hole and the nut are formed in the same polygonal or elongated hole shape and are unable to rotate relative to each other, so that a sufficient tightening torque can be obtained when the bolt is screwed into the nut.

1A is a plan view of a plate with screw holes welded to a workpiece, and FIG. 1B is a side cross-sectional view of a workpiece fastened with a bolt to the screw holes of the plate. 1A and 1B are explanatory diagrams showing another conventional example, in which (a) is a cross-sectional side view of an inverted U-shaped plate with a nut welded thereto being welded to a workpiece, (b) is a cross-sectional side view of a so-called cap nut, and (c) is a cross-sectional side view of a nut welded to the inner surface of the workpiece. 1A is an explanatory diagram of a nut mounting structure near a welded portion according to one embodiment of the present invention, in which (a) is an oblique view of a mounting plate, (b) is an oblique view of a nut accommodated in an attachment hole of the mounting plate, and (c) is a cross-sectional side view of the mounting plate welded to a member to be mounted. 4A is a side cross-sectional view of the nut of FIG. 3C when a bolt is screwed into the nut to fasten the fastened members, and FIG. 4B is a side cross-sectional view showing a first modified example. 1A is a side cross-sectional view showing a second modified example, and FIG. 1B is a side cross-sectional view showing a third modified example.

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific values shown in the embodiment are merely examples to facilitate understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid duplicated explanations, and elements not directly related to the present invention are not illustrated.

(Nut mounting structure near welded part)
3(a), 3(b), and 3(c), a nut attachment structure 1 near a welded portion according to one embodiment of the present invention includes a mounting plate 3 having a bent portion 2 on its edge, a weld bead 5 formed by welding the bent portion 2 of the mounting plate 3 to a mounting member (e.g., an axle case) 4, a gap W formed between the mounting plate 3 and the mounting member 4 other than the bent portion 2, a hexagonal mounting hole 6 formed through the mounting plate 3 other than the bent portion 2, a nut 7 formed in the same shape (hexagonal) as the mounting hole 6 and non-rotatably received in the mounting hole 6 via a clearance C, and a flange 8 extending from the nut 7 into the gap W. Each component will be described below.

(Mounting plate 3, bent portion 2)
As shown in Fig. 3(a), the mounting plate 3 is made of a steel plate having a thickness of, for example, about 8 to 10 mm, and includes bent portions 2 formed in a stepped shape at both edge portions in the width direction, and a flat portion 9 formed in a flat shape in the portion other than the bent portions 2, i.e., between the bent portions 2. The step W between the lower surface of the bent portion 2 and the lower surface of the flat portion 9 is set to, for example, about 4 to 6 mm. The dimension of this step W becomes the dimension of the gap W formed between the flat portion 9 of the mounting plate 3 and the mounted member 4 when the bent portions 2 of the mounting plate 3 are welded to the mounted member 4, as shown in Fig. 3(c).

(Mounting hole 6)
As shown in Fig. 3(a), four hexagonal mounting holes 6 are formed in the flat plate portion 9 of the mounting plate 3. The shape of the mounting holes 6 is not limited to a hexagon, but may be a triangle, a rectangle, a pentagon, a heptagon or more, or may be an ellipse. The mounting plate 3 having such mounting holes 6 and step portions 2 is formed by piercing the mounting holes 6 in the central flat plate portion 9 and forming (press forming) the bent portions 2 at both ends by pressing a flat blank plate. The number of mounting holes 6 is not limited to four.

(Nut 7, clearance C, weld bead 5)
As shown in Figures 3(b) and 3(c), a nut 7 of the same shape as the mounting hole 6 is accommodated in the mounting hole 6 of the mounting plate 3 so as not to rotate with the mounting hole 6 via a predetermined clearance C. As shown in Figure 4(a), the clearance C is a dimension that prevents the nut 7 from rotating together with the bolt 10 inside the mounting hole 6 when the bolt 10 is screwed into the threaded hole of the nut 7 and a predetermined tightening torque is applied, and is set to a dimension that can function as a gap of an air insulation layer that prevents the threaded hole of the nut 7 from being thermally deformed by welding heat when the end face of the bent portion 2 of the mounting plate 3 is welded to the attached member 4 (5 is a weld bead) as shown in Figure 3(c), and is set to, for example, about 0.5 to 1.5 mm.

(Flange 8)
As shown in FIG. 3C, the nut 7 is integrally formed with a flange 8 extending from its lower portion into the gap W between the lower surface of the flat portion 9 of the mounting plate 3 and the upper surface of the member 4 to be attached. The flange 8 is formed in a disk shape, and in order to prevent the nut 7 from falling off the mounting hole 6, the outer diameter of the flange 8 is set to be, for example, 5 to 7 mm larger than the dimension between the vertices of the hexagonal hole of the mounting hole (hexagonal in this embodiment) 6. The thickness of the flange 8 is about 1 to 2 mm thinner than the dimension (for example, 4 to 6 mm) of the step W (= gap W) between the lower surface of the bent portion 2 of the mounting plate 3 and the lower surface of the flat portion 9, and is set to, for example, about 3 to 5 mm. When the mounting plate 3 is in a state in which the nut 7 with such a flange 8 is accommodated in the mounting hole 6, the end surface of the bent portion 2 is welded (weld bead 5) to the member 4 to be attached.

(Thickness of nut 7 X)
As shown in Fig. 3(c), the thickness X of the nut 7 accommodated in the mounting hole 6 of the flat plate portion 9 of the mounting plate 3 is set to be less than the thickness Y of the flat plate portion 9 of the mounting plate 3, for example, about 1.5 to 2.5 mm smaller than the thickness Y. As a result, as shown in Fig. 4(a), when the bolt 10 is screwed into the screw hole of the nut 7 and the fastened member (e.g., an L-shaped plate) 11 is sandwiched between the bolt 10 and the nut 7, the flange 8 of the nut 7 is slightly deflected, and the fastened member 11 is pressed against the upper surface of the flat plate portion 9 of the mounting plate 3 and firmly fixed. At this time, the restoring force of the deflected flange 8 presses the threads of the bolt 10 and the threads of the nut 7 in the axial direction, preventing the bolt 10 from loosening.

(Action and Effects)
The nut attachment structure 1 near a welded portion according to this embodiment having the above-described configuration can provide the following effects.

As shown in FIG. 3(c), the nut 7 is accommodated in the mounting hole 6 of the mounting plate 3 via a clearance C, and the clearance C serves as an air insulation layer when the end face of the bent portion 2 of the mounting plate 3 is welded to the mounting member 4. Therefore, even if the distance L from the welded portion (weld bead 5) to the nut 6 is short, the deformation of the screw hole of the nut 7 due to welding heat can be suppressed, and the retapping of the screw hole is unnecessary. In other words, even if the mounting space for mounting the mounting plate 3 is limited, such as in the case of an axle case, for example (see peripheral part g in FIG. 1(b)), the deformation of the screw hole of the nut 7 due to welding heat can be suppressed, and the retapping of the screw hole is unnecessary. In addition, there is no need to form a through hole for retapping in the mounting member (axle case) 4.

As shown in Figures 3(b) and 3(c), the nut 7 is housed in the mounting hole 6 of the mounting plate 3, so the dimension X of the nut 7 in the height (thickness) direction is absorbed by the plate thickness Y of the mounting plate 3, and the dimension H of the mounting plate 3 in the height (thickness) direction can be reduced compared to the conventional example shown in Figures 2(a) and 2(b). Therefore, even if the attached member 4 is, for example, an axle case, and there is a peripheral part g shown in Figure 1(b) in the height direction of the nut, layout constraints are relaxed. In other words, the degree of freedom in layout is improved for the peripheral part g in the height direction of the nut 7 of the attached member 4.

As shown in Figures 3(b) and 3(c), the hexagonal nut 7 is housed in the hexagonal mounting hole 6 so that it cannot rotate, and as shown in Figure 4(a), it is possible to obtain a sufficient tightening torque when the bolt 10 is screwed into the screw hole of the nut 7. As mentioned above, the nut 7 and the mounting hole 6 may be made to have the same polygonal or elongated hole shape so that the nut 7 cannot rotate relative to the mounting hole 6.

As shown in FIG. 3(c), the thickness X of the nut 7 accommodated in the mounting hole 6 is set smaller than the thickness Y of the mounting plate 3. Therefore, as shown in FIG. 4(a), when the bolt 10 is screwed into the screw hole of the nut 7, the flange 8 of the nut 7 bends slightly, and the fastened member (L-shaped plate) 11 is pressed against the flat plate portion 9 of the mounting plate 3 and firmly fixed. At this time, the restoring force of the bent flange 8 presses the threads of the bolt 10 and the threads of the nut 7 in the axial direction, preventing the bolt 10 from loosening.

(First Modification)
Fig. 4(b) shows a first modified example of the present invention. The nut attachment structure 1a in the vicinity of the welded portion according to this first modified example differs from the previous embodiment shown in Fig. 4(a) in that the flange 8 of the nut 7 is spot-welded or brazed to the underside of the attachment plate 3 (12 is a spot-welded or brazed portion), but otherwise has the same configuration as the previous embodiment. Therefore, the same components as those in the previous embodiment are given the same reference numerals and their explanations are omitted.

According to the first modified example shown in FIG. 4(b), the flange 8 of the nut 7 is spot welded or brazed to the mounting plate 3, so that the nut 7 and the mounting plate 3 become an integrated part, and when this integrated part is welded to the mounting member (e.g., the axle case) 4, the nut 7 will not fall off, improving workability. In addition, because spot welding produces a small welded part and brazing is performed at a lower temperature than welding, thermal deformation of the screw hole of the nut 7 due to spot welding or brazing is suppressed. Otherwise, the basic effects of the first modified example are the same as those of the previous embodiment.

(Second Modification)
A second modification of the present invention is shown in Fig. 5(a). The nut mounting structure 1b near the welded portion according to this second modification is different from the first embodiment shown in Fig. 4(a) in that the thickness X of the nut 7 accommodated in the mounting hole 6 of the flat portion 9 of the mounting plate 3 is equal to or greater than the thickness Y of the flat portion 9 of the mounting plate 3 (for example, X-Y = 2 to 3 mm), and the flange 8 of the nut 7 is spot-welded or brazed to the underside of the mounting plate 3 (12 is a spot-welded or brazed portion), but otherwise has the same configuration as the first embodiment. Therefore, the same components as those in the first embodiment are given the same reference numerals and will not be described.

According to the second modified example shown in FIG. 5(a), the thickness X of the nut 7 accommodated in the mounting hole 6 of the mounting plate 3 is equal to or greater than the thickness Y of the mounting plate 3. Therefore, when the bolt 10 is screwed into the screw hole of the nut 7 to fasten the fastened member (L-shaped plate) 11, a gap (X-Y) is formed between the bottom surface of the fastened member 11 and the top surface of the flat portion 9 of the mounting plate 3. However, since the flange 8 of the nut 7 is spot-welded or brazed to the mounting plate 3, the fastened member 11 is prevented from rattling. In addition, since the welded portion is small in spot welding and brazing is performed at a lower temperature than welding, thermal deformation of the screw hole of the nut due to spot welding or brazing is suppressed. In addition, the basic effects of the second modified example are the same as those of the first embodiment.

(Third Modification)
FIG. 5(b) shows a third modified example of the present invention. The nut mounting structure 1c near the welded portion according to this third modified example is similar to the second modified example shown in FIG. 5(a) in that the thickness X of the nut 7 accommodated in the mounting hole 6 of the flat portion 9 of the mounting plate 3 is equal to or greater than the thickness Y of the flat portion 9 of the mounting plate. However, it differs from the second modified example in that the flange 8 of the nut 7 is not spot-welded or brazed to the mounting plate 3, and a spacer piece 13 is interposed between the mounting plate 3 and the fastened member 9. The spacer piece 13 is attached to the mounting plate 3 or the fastened member 11 by adhesive or the like. The thickness of the spacer piece 13 is, for example, 1.5 to 2.5 mm larger than the dimension X-Y. In addition, the material of the spacer piece 13 is preferably a metal softer than the material of the mounting plate 3 and the material of the fastened member (L-shaped plate) 11. In addition, the basic configuration of the third modified example is similar to the first embodiment shown in FIG. 4(a).

According to the third modified example shown in FIG. 5(b), a spacer piece 13 is interposed between the mounting plate 3 and the fastened member 11, so that when the bolt 10 is screwed into the threaded hole of the nut 7 to fasten the fastened member 11, the spacer piece 13 is slightly crushed and the flange 8 of the nut 7 is slightly deflected, firmly fixing the fastened member 11. At this time, the restoring force of the crushed spacer piece 13 and the deflected flange 8 presses the threads of the bolt 10 and the threads of the nut 7 in the axial direction, preventing the bolt 10 from loosening. Otherwise, the basic effects of the third modified example are the same as those of the first embodiment.

The above describes a preferred embodiment of the present invention with reference to the attached drawings, but it goes without saying that the present invention is not limited to the above-mentioned embodiment, and various modifications and alterations within the scope of the claims also fall within the technical scope of the present invention.

The present invention can be used in a nut mounting structure near a welded part that can suppress deformation of the threaded part due to welding heat even when the distance from the welded part to the nut is short, can reduce the mounting space in the height direction of the nut as much as possible, and can be used to increase the tightening torque.

Reference Signs List 1 Nut mounting structure near welded portion 2 Bent portion 3 Mounting plate 4 Mounted member 5 Weld bead 6 Mounting hole 7 Nut 8 Flange 9 Flat portion of mounting plate other than bent portion 10 Bolt 11 Fastened member 12 Spot welded portion or brazed portion W Gap C Clearance X Thickness Y of nut accommodated in mounting hole of mounting plate Thickness of mounting plate

Claims (3)

A mounting plate having a bent portion on an edge thereof;
a weld bead formed by welding the bent portion of the mounting plate to the workpiece;
a gap formed between a portion of the mounting plate other than the bent portion and the workpiece;
a polygonal or elongated mounting hole formed through a portion of the mounting plate other than the bent portion;
a nut formed in the same shape as the mounting hole and non-rotatably received in the mounting hole with a clearance therebetween;
a flange extending from the nut into the gap ,
A nut mounting structure near a welded portion , characterized in that a flange of a nut received in an attachment hole of the mounting plate is spot welded or brazed to the mounting plate . 2. The nut mounting structure near a welded portion according to claim 1, wherein the thickness of the nut received in the mounting hole of the mounting plate is equal to or greater than the thickness of the mounting plate. 3. The nut mounting structure according to claim 1, wherein a bolt is screwed into the nut, and a fastened member is sandwiched between the bolt and the nut.

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