JP7496735B2 - Dead axle structure - Google Patents

Description

The present invention relates to a dead axle structure in which mounting members for a suspension system, etc. are welded to the dead axle case body.

Conventionally, a dead axle structure in which suspension mounting members and the like are welded to the dead axle case body is known, as shown in FIG. 3(a). The dead axle structure 101 shown in the figure has a spindle 103 for mounting a hub, suspension mounting members for mounting a suspension system (e.g., a torque rod bracket 104 and a spring seat 105), braking mounting members for mounting a braking system (e.g., a brake flange 106), and the like welded to a hollow dead axle case body 102 arranged horizontally.

Some members attached to the dead axle case body 102, such as the torque rod bracket 104 shown in the figure, are welded at a position offset upward with respect to the neutral axis C of the dead axle case body 102 (usually the center axis of the dead axle case body 102). For this reason, the welded portion w of the torque rod bracket 104 is also offset upward with respect to the neutral axis C. In addition, members arranged almost symmetrically with respect to the neutral axis C, such as the spring seat 105 and the brake flange 106, may not be welded at their lower portions (in the cross-sectional view F-F and cross-sectional view G-G of FIG. 3(a)) in consideration of the fact that high tensile stress occurs in the lower portion of the dead axle case body 102 due to the application of vertical loads (axle loads) from the vehicle during use. In this way, the welded portion w of the member attached to the dead axle case body 102 is offset upward with respect to the neutral axis C of the dead axle case body 102. As a result, the dead axle case body 102 after welding is deformed to be convex downward as a whole, as shown in Figure 3(b), due to welding distortion caused by shrinkage as the welded portion solidifies. Note that in Figure 3(b), the deformation of the dead axle case body 102 is shown in an exaggerated manner.

Such deformation of the dead axle case body 102 impairs the coaxiality of the spindles 103 attached to the left and right ends. On the other hand, in order to reduce wheel resistance when attached to a vehicle and enable the vehicle to run straight, it is necessary to keep the coaxiality of the left and right spindles 103 within a fairly small range.

For this reason, conventionally, the deformation of the dead axle case body 102 near the spindle 103 is corrected by, for example, a pressing method as shown in FIG. 4. In the pressing method, the dead axle case body 102 is placed upside down on a pair of support stands S as shown in the figure (the support stands S support the maximum diameter parts of the left and right spindles 103), and pressure is applied from above to either the left or right spring seat 105. Since the spring seat 105 has a higher rigidity than the dead axle case body 102, it can bend the dead axle case body 102 in the opposite direction to the deformation caused by welding distortion. By performing this operation on the left and right spindles 103, the coaxiality can be adjusted. However, the amount of correction may differ between the left and right due to the variation in the welding distortion of the deformation of the dead axle case body 102, and also depends on the way the load is applied when pressing and the way the dead axle case body 102 is placed on the support stands S, so the correction operation requires the skill of the worker. In addition, multiple operations must be performed as described above, which increases the number of work steps.

In addition, in the press method, the dead axle case body 102 is deformed to correct the part with the lowest cross-sectional rigidity. In the dead axle case body 102 shown in FIG. 4, the part H-H (outside a predetermined distance from the brake flange 106) has a circular cross-sectional shape, and the part I-I (inside a predetermined distance from the brake flange 106) has a rectangular cross-sectional shape, and the shape change part (rounded corner change part) between them is the part with the lowest rigidity. Therefore, when correcting the dead axle case body 102 by the press method, this rounded corner change part is deformed to adjust the coaxiality of the left and right spindles 103. On the other hand, for example, some dead axle case bodies for vehicles equipped with air suspension have a circular cross-sectional shape in all places and do not have the above-mentioned rounded corner change part. In such a case where the cross-sectional shape is constant, there are no parts with locally low rigidity, making correction by the press method difficult. In this case, as shown in FIG. 5, a method of changing the welding order may be used. In this method, first, the torque rod bracket 104, spring seat 105, etc. are welded to the dead axle case body 102, and in the next process, the spindle 103 is pressed onto the left and right ends of the dead axle case body 102 without correcting the welding distortion. With this method, even if the dead axle case body 102 is deformed by the previous welding process, the left and right spindles 103 are kept coaxial, and correction work such as with the press method is not required. However, because the welding sequence of this method is different from that of existing products, it will lead to increased costs due to the addition of production equipment and the complicated assembly process sequence.

The welding device disclosed in the following Patent Document 1 is known as a technology for reducing residual stress caused by welding. The device uses a mechanism for relatively moving the first and second members to be welded to release deformation that occurs during welding, and measures the amount of deformation and moves the first and second members relatively to cancel out the deformation. In other words, this welding device requires many actuators and sensors, which makes the overall device configuration complicated and inevitably increases costs.

Local heating straightening is also known as a method for straightening deformations in components after welding. In local heating straightening, the component is heated, for example, with a gas burner (for example, until the part to be heated reaches approximately 600-700°C), and then cooled, causing the heated part to shrink and straighten the deformation. However, this method reduces the strength of the base material due to heating, so if it is applied to the dead axle case body 102, there is a risk that the required yield strength (deformation strength from road reaction force) will not be maintained. In addition, it takes time for the heated part to reach the specified temperature, and the amount of heat input changes depending on the power of the gas burner and the way the torch is moved, making it difficult to stabilize the amount of straightening.

JP 2006-272368 A

In this way, when the torque rod bracket 104, spring seat 105, etc. are welded to the dead axle case body 102, the dead axle case body 102 deforms, affecting the coaxiality of the left and right spindles 103. In addition, conventional methods for correcting deformation of the dead axle case body 102 have problems in that they reduce strength and do not maintain stable quality, and they also have problems in that they increase the number of work steps and equipment costs, inevitably resulting in increased costs.

In view of these points, the objective of the present invention is to provide a technology that can stably ensure the coaxiality of the spindles installed at both ends of the dead axle case body in a dead axle structure in which mounting members for a suspension device, etc. are welded to the dead axle case body, while reducing the number of work steps compared to conventional methods without increasing equipment costs.

The present invention is a dead axle structure in which at least one of a suspension mounting member and a braking device mounting member is welded to a hollow dead axle case body arranged horizontally and having spindles at both ends, with a weld at least in a position offset upwardly with respect to the neutral axis of the dead axle case body, the suspension mounting member having a bracket in the longitudinal center of the dead axle case body, the bracket being welded to the dead axle case body at the weld provided above the neutral axis, a bead-on-plate weld provided on the side of the dead axle case body and in the longitudinal center of the dead axle case body , at a position located below the neutral axis and above the lowest part of the dead axle case body, and at least a portion of the bead-on-plate weld is positioned directly below the weld so as to overlap the weld of the bracket in the longitudinal direction of the dead axle case body .

In the above dead axle structure, it is preferable that the bead-on-plate weld is provided at a location below the neutral axis and above a lower weld end of at least one of the welds of the suspension mounting member and the welds of the brake mounting member.
In the above dead axle structure, it is preferable that the bead-on-plate welded portion overlaps the entire welded portion of the bracket in the longitudinal direction.

The present invention also provides a dead axle structure in which at least one of a suspension attachment member and a brake attachment member is welded to a hollow dead axle case body that is horizontally arranged and has spindles at both ends, with a weld portion at least located upwardly with respect to the neutral axis of the dead axle case body, the suspension attachment member having a bracket in the longitudinal center of the dead axle case body, the bracket being welded to the dead axle case body at the weld portion located above the neutral axis, a steel plate is welded to the side of the base body and to the longitudinal center of the dead axle case body so as to have a weld bead at a location below the neutral axis and above the lowest part of the dead axle case body , the steel plate is welded to the dead axle case body by the weld beads which are provided on upper and lower edges of the steel plate and extend in the longitudinal direction, and at least a portion of the weld bead is positioned directly below the weld part of the bracket so as to overlap with the weld part of the bracket in the longitudinal direction of the dead axle case body .

In the above-mentioned dead axle structure, it is preferable that the steel plate is welded so as to have a weld bead at a location below the neutral axis and above a lower weld end of at least one of the welded portions of the suspension mounting member and the welded portion of the brake mounting member.
In the above dead axle structure, it is preferable that the weld bead overlaps the entire welded portion of the bracket in the longitudinal direction.

According to the present invention, in a dead axle structure in which mounting members for a suspension device are welded to the dead axle case body, it is possible to stably ensure the coaxiality of the spindle while reducing the number of work steps compared to conventional methods without increasing equipment costs.

FIG. 1 is a diagram showing a schematic diagram of an embodiment of a dead axle structure according to the present invention. FIG. 10 is a diagram showing a schematic diagram of another embodiment of a dead axle structure according to the present invention. 1A and 1B are diagrams showing a conventional dead axle structure and a modified example thereof; FIG. 1 is a diagram illustrating a conventional correction method. FIG. 1 is a diagram showing a schematic diagram of a method for avoiding a conventional correction method.

Below, we will explain an example of a dead axle structure according to the present invention, with reference to the attached drawings.

Figure 1 is a schematic diagram of one embodiment of a dead axle structure according to the present invention. The dead axle structure 1 of this embodiment includes a dead axle case body 2, a spindle 3, a torque rod bracket 4, a spring seat 5, and a brake flange 6. The dead axle case body 2 also includes a bead-on-plate welded portion 7.

The dead axle case body 2 is formed, for example, by pressing a metal plate, and is shaped to be hollow. As with the conventional dead axle case body 2 shown in FIG. 3, the dead axle case body 2 of this embodiment has a circular cross-sectional shape at the illustrated portion A-A (a predetermined distance outside the brake flange 6), a rectangular cross-sectional shape at the portion B-B (a predetermined distance inside the brake flange 6), and the cross-sectional shape changes from circular to rectangular between these (rounded corner change portion). In this way, the dead axle case body 2 of this embodiment has a cross-sectional shape that changes along the longitudinal direction, but the cross-sectional shape is symmetrical with respect to the central axis, and the neutral axis C coincides with the central axis.

The spindle 3 supports the wheels when installed on a vehicle. In this embodiment, the spindle 3 is cylindrical and is attached to the left and right ends of the dead axle case body 2 by welding.

The torque rod bracket 4 is used to attach a torque rod that constitutes the suspension system. In this embodiment, the torque rod bracket 4 is formed in a roughly U-shape and is attached by welding above the neutral axis C with the dead axle case body 2 positioned horizontally. In FIG. 1, the welded portion W where the torque rod bracket 4 is welded to the dead axle case body 2 is shown by a thick line. As shown in the figure, the welded portion W of the torque rod bracket 4 is located above the neutral axis C.

The spring seat 5 is used to attach the spring that constitutes the suspension system. The spring seat 5 in this embodiment is formed in a rectangular shape like the spring seat 105 in FIG. 3, and is attached to the dead axle case body 2 by welding. When welding the spring seat 5, the lower part of the spring seat 5 is not welded, taking into consideration that high tensile stress is generated in the lower part of the dead axle case body 2 due to the application of vertical loads (axle loads) during use, and the welded part W is offset upward with respect to the neutral axis C as shown in the figure. The welded lower end WL of the welded part W in the spring seat 5 (see the cross-sectional view B-B in FIG. 1) is located on the reference line L shown in the figure.

The brake flange 6 is used to attach a braking device. In this embodiment, the brake flange 6 is formed in a ring shape and is attached to the dead axle case body 2 by welding. The brake flange 6 also has a non-welded portion at the bottom, similar to the spring seat 5. In this embodiment, as shown in the cross-sectional view A-A, the lower 120° range is the non-welded portion, and the welded portion W is offset upward with respect to the neutral axis C. Here, the welded lower end WL of the welded portion W in the brake flange 6 (see the cross-sectional view A-A in FIG. 1) is on the reference line L described above and is located at the same height as the welded lower end WL of the spring seat 5.

The bead-on-plate welds 7 are also called beaded beads, and are formed by overlay welding a filler material such as a welding rod or welding wire to the side of the dead axle case body 2. The bead-on-plate welds 7 are provided in a portion located below the neutral axis C and above the lowest part PL of the dead axle case body 2 (see the cross-sectional view A-A in FIG. 1). As shown in the figure, multiple bead-on-plate welds 7 are provided in this embodiment, but all of them are provided in a portion located below the neutral axis C and above the reference line L. In this embodiment, three bead-on-plate welds 7 are provided on the surface of the dead axle case body 2 below the torque rod bracket 4, as shown in the cross-sectional view C-C in FIG. 1, and two more bead-on-plate welds 7 are provided so as to overlap these (three bead-on-plate welds 7 are provided in the first layer and two bead-on-plate welds 7 are provided in the second layer). In addition, two bead-on-plate welds 7 are provided between the torque rod bracket 4 and the spring seat 5 with a gap in the vertical direction.

In the dead axle case body 2 of this embodiment, the welded parts W of the torque rod bracket 4, spring seat 5, and brake flange 6 are positioned upwardly with respect to the neutral axis C. Therefore, the dead axle case body 2 after welding these parts is deformed to be convex downward as a whole due to welding distortion caused by shrinkage of the welded parts, similar to the dead axle case body 102 shown in FIG. 3(b). On the other hand, in the dead axle structure 1 of this embodiment, since the bead-on-plate welded part 7 is provided below the neutral axis C, welding distortion also occurs below the neutral axis C. In other words, since the bead-on-plate welded part 7 acts to cancel out the welding distortion caused by the welded part W, the deformation of the dead axle case body 2 caused by the welded part W can be corrected by the bead-on-plate welded part 7. Note that the length, number, number of layers, vertical position, horizontal position, etc. of the bead-on-plate welded part 7 can be appropriately set according to the amount of deformation of the dead axle case body 2, and are not limited to those shown in the figure.

According to the dead axle structure 1 of this embodiment, the deformation of the dead axle case body 2 can be corrected, so the coaxiality of the left and right spindles 3 can be ensured. In addition, the welding time when forming the bead-on-plate welded portion 7 is shorter than that of the above-mentioned local heating correction method, and since only local heating is required, the strength of the dead axle case body 2 is not reduced. If a high-strength filler material is selected for forming the bead-on-plate welded portion 7, the bead-on-plate welded portion 7 can also improve the strength of the dead axle case body 2. Furthermore, the bead-on-plate welded portion 7 can basically exhibit stable quality as long as the outer diameter of the filler material used, the welding conditions (current, voltage, etc.), and the welding amount (weld length, number, number of layers) do not change, so the amount of correction can be stabilized. In addition, there is no need to change the order of component installation in the manufacturing process, and there is no need to correct the dead axle case body 2 in a later process as in the above-mentioned pressing method, so the number of work steps can be reduced compared to the conventional method without increasing equipment costs. Although the dead axle case body 2 has rounded corners where the cross-sectional shape changes from circular to rectangular, the shape of the dead axle case body 2 is not limited to this, and the cross-sectional shape may be circular in all places and may not have rounded corners.

The above effect can be achieved by providing the bead-on-plate weld 7 at a location below the neutral axis C and above the lowest part PL of the dead axle case body 2. However, if the bead-on-plate weld 7 is provided below the neutral axis C and above the lower end WL of at least one of the welds W of the spring seat 5 and the weld W of the brake flange 6, damage to the bead-on-plate weld 7 caused by the application of vertical loads (axle loads) to the dead axle case body 2 during use can be prevented. In particular, if the bead-on-plate weld 7 is provided below the neutral axis C and above the lower end WL of both the weld W of the spring seat 5 and the weld W of the brake flange 6, as in this embodiment, damage to the bead-on-plate weld 7 can be more reliably prevented.

The dead axle structure according to the present invention can also be embodied as shown in FIG. 2. The dead axle structure 11 shown in FIG. 2(a) includes the dead axle case body 2, the spindle 3 (not shown in FIG. 2), the torque rod bracket 4, the spring seat 5, and the brake flange 6, as in the dead axle structure 1 described above, but instead of the bead-on-plate welded portion 7, a steel plate 12 is welded to the side of the dead axle case body 2. The weld bead 13 formed when the steel plate 12 is welded is located below the neutral axis C and above the lowest part PL of the dead axle case body 2. This provides the same effect as the bead-on-plate welded portion 7 described above. Furthermore, according to the dead axle structure 11, the steel plate 12 also provides the effect of improving the strength of the dead axle case body 2. In addition, in this embodiment, if the weld bead 13 welded to the top of the steel plate 12 is located above the lower end WL of at least one of the welded parts W of the spring seat 5 and the welded part W of the brake flange 6, damage from the weld bead 13 that may occur when a vertical load (axle load) is applied to the dead axle case body 2 during use can be prevented.

The number and positions of the steel plates 12 to be attached, and the number, length, and positions of the weld beads 13 may be set appropriately according to the deformation of the dead axle case body 2. The steel plates 12 are not limited to being flat as in FIG. 2(a), and may be any shape. Also, holes (screw holes) may be provided as in the case of steel plate 14 shown in FIG. 2(b), in which case they can be used as mounting members for piping and wiring.

Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and various modifications and alterations are possible within the scope of the spirit of the present invention described in the claims unless otherwise specifically limited in the above description. Furthermore, the effects of the above embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above effects.

1, 11: Dead axle structure 2: Dead axle case body 3: Spindle 4: Torque rod bracket (mounting member for suspension device)
5: Spring seat (mounting member for suspension system)
6: Brake flange (mounting member for braking device)
7: Bead-on-plate welded portion 12, 14: Steel plate 13: Welded bead C: Neutral axis PL: Bottom part (bottom part of dead axle case body)
W: Welded part WL: Lower end of weld

Claims (6)

A dead axle structure in which at least one of a suspension mounting member and a brake mounting member is welded to a hollow dead axle case body arranged horizontally and having spindles at both ends, with a welded portion at a position offset upward with respect to the neutral axis of the dead axle case body,
The suspension mounting member includes a bracket in a longitudinal center portion of the dead axle case body, the bracket being welded to the dead axle case body at the weld portion provided above the neutral axis,
A bead-on-plate weld is provided at a side portion of the dead axle case body and at a central portion in a longitudinal direction of the dead axle case body , the bead-on-plate weld is provided at a portion located below the neutral axis and above a lowermost portion of the dead axle case body ,
A dead axle structure characterized in that at least a portion of the bead-on-plate weld is positioned directly below the weld of the bracket so as to overlap with the weld in the longitudinal direction of the dead axle case body . The dead axle structure according to claim 1, characterized in that the bead-on-plate weld is provided at a location below the neutral axis and above the lower end of at least one of the welds of the suspension mounting member and the welds of the brake mounting member. 2. The dead axle structure of claim 1, wherein the bead-on-plate weld overlaps the entirety of the weld of the bracket in the longitudinal direction. A dead axle structure in which at least one of a suspension mounting member and a brake mounting member is welded to a hollow dead axle case body arranged horizontally and having spindles at both ends, with a welded portion at a position offset upward with respect to the neutral axis of the dead axle case body,
The suspension mounting member includes a bracket in a longitudinal center portion of the dead axle case body, the bracket being welded to the dead axle case body at the weld portion provided above the neutral axis,
A steel plate is welded to the side of the dead axle case body and the center of the dead axle case body in the longitudinal direction so as to have a weld bead at a portion located below the neutral axis and above the lowest portion of the dead axle case body ,
The steel plate is welded to the dead axle case body by the weld beads provided on the upper and lower sides of the steel plate and extending in the longitudinal direction,
A dead axle structure, characterized in that at least a portion of the weld bead is positioned directly below the weld portion of the bracket so as to overlap the weld portion in the longitudinal direction of the dead axle case body . 5. The dead axle structure according to claim 4, wherein the steel plate is welded so as to have the weld bead at a portion located below the neutral axis and above a lower weld end of at least one of the welded portion of the suspension mounting member and the welded portion of the brake mounting member. 5. The dead axle structure according to claim 4, wherein the weld bead overlaps the entire weld of the bracket in the longitudinal direction.

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