JPH0736870Y2 - Inner channel connection structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a frame structure having a box-shaped closed cross section that constitutes a vehicle lower frame member of, for example, an automobile, and particularly to a frame side which is a main component of this frame. The present invention relates to a rail inner channel coupling structure.

[Conventional technology]

Conventionally, since a frame that constitutes a lower body frame member of an automobile or the like is long in a vehicle front-rear direction, an inner channel that forms a box-shaped closed cross section is combined with a long frame side rail that is a main component of this frame. It is divided into a front side and a rear side and is linearly welded and joined at a predetermined portion in the vehicle front-rear direction.

Then, for example, Japanese Utility Model Laid-Open No. 61-42385 (Japanese Utility Model Application No. 59-127568) has been proposed as a structure showing a binding structure of both inner channels thus divided. It is shown in FIG.

As shown in FIG. 6 to FIG. 8, the divided front inner channel 10 and rear inner channel 20 having a U-shaped cross section are linearly welded and coupled to each other to form a long frame side rail 30 having a U-shaped cross section. Together, they form a box-shaped closed-section frame extending in the vehicle front-rear direction.

As a connecting structure of the both inner channels 10 and 20, for example, a structure in which the end portion 210 of the rear inner channel 20 is positioned inside the end portion 110 of the front inner channel 10 and is overlapped and coupled, A detailed description will be given with reference to FIGS. 6 to 8.

First, when the inner channels 10 and 20 having the U-shaped cross section are connected to each other, the inner channels 10 and 20 become linear, that is, the U-shaped outer surfaces of the inner channels 10 and 20.
U-shaped side surfaces 120a, 220a and U-shaped base surface 12 which are 120 and 220
In order to make 0b and 220b (hereinafter, simply referred to as outer surfaces 120 and 220) flush with each other, the end 21 of the rear inner channel 20 is formed.
The vicinity of 0 is dropped inward by a dimension corresponding to the plate thickness of the front inner channel 10 to form a stepped shape (this dropped stepped portion is generally referred to as a back cut portion, hereinafter referred to as a back cut portion 40). ) Together with the front inner channel
10 is formed straight up to its end 110.

Then, in the back cut portion 40 near the end 210 of the rear inner channel 20, the end of the front inner channel 10 is
The straight portion near the end portion 110 of the front inner channel 10 and the spine cut portion 4 near the end portion 210 of the rear inner channel 20 by making the 110 close to each other.
By stacking the straight parts of the drop-in step by 0, both inner channels 10, as shown in the figure,
Each outer surface 120, 220 of 20 is linear in a flush state, and both inner channels 10, 20 thus linearly overlapped are long frame side rails having a U-shaped cross section.
The inner side of the frame side rail 30 and the inner side channels 310, 2
The side surfaces 120a and 220a of 0 are overlapped.

Next, the end portion (110) of the end portion 110 of the front inner channel 10 that does not overlap the side surface 310 of the frame side rail 30 and the rear inner channel 2
The outer surface 220 in the vicinity of the spine cut portion 40 of 0 is joined by welding, and each side surface of both the inner channels 10 and 20.
The frame side rail 30 at the portion where the side surfaces 310 of the frame side rail 30 are overlapped with 120a, 220a.
The side end portion 320 of each of the inner channels 10 and the side surfaces 120a and 220a of the inner channels 10 and 20 are welded and joined together in the longitudinal direction.

Here, the end portion 110 of the side surface 120 a of the front inner channel 10 that is overlapped with the side surface 310 of the frame side rail 30 is the frame side rail 30.
Since it is located on the inner side of the side surface 310, the welding is not performed. 7 and 8, the outer surface 220 of the rear inner channel 20 which is a portion other than the above portion at the end portion 110 of the front inner channel 10 is shown.
The weld bead at the welded joint portion with is indicated by reference numeral 50.

Due to such a connected state, the weld bead 50 formed by the welded connection between the end portion 110 of the front inner channel 10 and the outer surface 220 of the rear inner channel 20 has a back cut portion near the end portion 210 of the rear inner channel 20. It is overlapped with 40 or is placed very close to it.

Further, each end portion 11 of both inner channels 10 and 20 is
At a predetermined portion of the base surface 120b of the front inner channel 10 in the overlapping portion in the vicinity of 0 and 210, a long hole 70 extending in the lateral direction is formed, and the peripheral portion of the long hole 70 and the end portion 210 of the rear inner channel 20. By connecting the surface (base surface 220b) in the vicinity by plug welding, the bonding strength of both the inner channels 10 and 20 is increased.

In the structure in which the inner channels are split and joined to the long frame side rail in this way, the overlapping portions near both ends of both inner channels are lengthened, and the overlapping welding joints are As an example of a conventional technique which is configured so that a torsional stress received from a mount bracket is not applied, for example, Japanese Utility Model Laid-Open No. 59-32574 (Japanese Utility Model Application No. 57-129094) is disclosed.
There is.

[Problems to be solved by the device]

However, in the case of the inner channel coupling structure shown in FIGS. 6 to 8, the end portion of the front inner channel 10 is formed at the back cut portion 40 near the end portion 210 of the rear inner channel 20.
110 has a structure in which they are superposed so as to be close to each other and weld-bonded to each other, and in particular, the base surface 220b and the side surface of the rear inner channel 20 in the drop step portion which is the back cut portion 40 in general.
The draw forming portion 410, which is a bent portion with respect to 220a, is a portion where stress is concentrated in terms of shape and the plate thickness is the smallest in press forming.

Particularly regarding the concentration of stress, as is clear from the stress distribution diagram of FIG. 9, the draw-formed portion 410 at the bent portion of the base surface 220b and the side surface 220a of the outer surface 220, which is the spine section 40 of the rear inner channel 20, is shown. The stress increases rapidly (that is, stress concentrates), and a larger stress concentrates as compared with the stress distribution diagram (FIG. 4) in the structure of the present invention described later.
The solid line in the figure is the stress distribution of the rear inner channel 20,
The broken line shows the stress distribution in the front inner channel 10. Therefore, in order to connect the end portion 110 of the front inner channel 10 and the outer surface 220 of the rear inner channel 20 to the draw-molded portion 410, in particular, in the region of the spine cut portion 40, the welding beads 50 overlap each other, or extremely. Since they are applied close to each other, the spine-cutting portion 40 near the end of the weld bead 50 and particularly the draw-forming portion 410 become the weakest portions, and the durability is also reduced.

On the other hand, in order to prevent such a problem, for example, it is conceivable to form the drop-in step which is the back cut portion 40 into a shape close to a straight line so that the dimensions gradually change. The back cut portion 4 at the welded portion between the side surface 220a of the inner channel 10 and the rear inner channel 20 and the side surface end 320 of the frame side rail 30.
Since the gap in the vicinity of 0 (hereinafter referred to as the lap welding portion 60) becomes large, the welded joint at this portion is not sufficient and the strength is reduced.

Further, it is conceivable that the shape of the spine cut portion 40 is not changed and the end portion 110 of the front inner channel 10 is simply separated from the spine cut portion 40 and superposed and coupled, but even with such a structure, Similarly, since the gap of the lap welding portion 60 becomes large, the same problem occurs.

In particular, if there is a gap in the lap weld 60 in this way,
Compared to the structure that eliminates this gap by filling the gap, the principal stress value will increase, so the strength will decrease and the durability will decrease, and the life due to this durability will also be about 3/4. Will end up.

Then, this invention makes it a subject to carry out welding connection by making the outer surface shape in one inner channel by which an end part is weld-bonded into a shape which does not concentrate stress on the other inner channel side.

[Means for solving the purpose]

In order to achieve the above-mentioned object, the present invention connects one end of one of a front inner channel and a rear inner channel having a U-shaped cross section, which are linearly connected to each other in the longitudinal direction, to the one end. Form a back cut portion that is dropped inward by the thickness equivalent to the thickness of the other inner channel, and make the portion beyond this back cut portion thin, and fit this thin portion inside the other inner channel. , And outside the inner channels, a frame side rail having a U-shaped cross section is arranged along the inner channels so as to cover a part of the outer surface of the inner channels. A portion of the portion not covered by the frame side rail is welded to the outer surface of the thinly formed portion, and the frame side rail is attached to both sides. An inner channel coupling structure welded to the outer surface of the inner channel, wherein the end portion of the other inner channel is spaced farther from the spine cut portion than the portion covered by the frame side rail. And a portion of the end portion of the other inner channel that is not covered by the frame side rail is welded to the outer surface of the thinly formed portion without welding beads on the spine cut portion. It is characterized by that.

[Action]

Therefore, according to this invention, the portion of the one inner channel that is narrower than the back cut portion is fitted inside the end of the other inner channel. In that case, the end portion of the other inner channel is formed so that the portion covered by the frame side rails is close to the spine cut portion and the portion exposed to the outside is largely separated from the spine cut portion. Since the weld bead is welded to the outer surface of one of the inner channels so that it does not hang on the back cut at a portion largely separated from the back cut, it is possible to prevent the strength of the back cut from decreasing due to the heat effect during welding. In addition, the weld beet does not overlap or approach the spine section to prevent stress concentration on the spine section, and the unwelded end, that is, the portion covered by the frame side rails By approaching the portion, the gap at the engaging portion becomes small, and the decrease in the bonding strength of both inner channels is effectively prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 to 5 show one embodiment of the present invention. FIG. 1 is a perspective view around welded joint portions of both inner channels and frame side rails, and FIG.
FIG. 2 is a plan view of II, FIG. 3 is a side view of FIG.
FIG. 5 is a stress distribution diagram around welded joints of both inner channels, and FIG. 5 is an experimental graph showing a stress ratio with respect to a plate thickness ratio (l / t) of both inner channels at the same portion.

Here, for example, a structure in which the vicinity of the end 21 of the rear inner channel 2 is set to the inner side and the vicinity of the end 11 of the front inner channel 1 is set to the outer side, and is overlapped and coupled, will be described as an example. As shown in FIG. 6, the vicinity of the end 21 of the rear inner channel 2 is formed inwardly in a stepped shape (hereinafter, the stepped part formed by the stepped-down shape is referred to as the spine section 4), and the vicinity of the end 21 is formed. Both the inner channels 1 and 2 are linearly arranged in a flush state by superimposing the vicinity of the end 11 of the front inner channel 1 and the side surfaces 12a and 22a of the inner channels 1 and 2 are substantially widthwise. The side surfaces 31 of the frame side rails 3 are overlapped so as to cover half of them. At this time, of the end portion of the front inner channel 1, the portion covered by the frame side rails 3 is made longer than the uncovered portion, and the extended portion for welding connection is the back cut portion 4 of the rear inner channel 2. Is formed so as to project in the direction.

The end 11 of the front inner channel 1 which is not overlapped with the side surface 31 of the frame side rail 3 and the back cutout 4 of the rear inner channel 2.
The outer surfaces 22 (side surface 22a and base surface 22b) in the vicinity are welded together, and the side surfaces 12a and 22a of both inner channels 1 and 2 and the side end 32 of the frame side rail 3 are welded together. At this time, the extended portion projecting from the end of the front inner channel 1 is arranged so as to fill the gap between the frame side rail 3 and the rear inner channel 2.

In addition, reference numeral 5 in the drawings of FIGS. 1 to 3 denotes a weld bead formed by welding connection of both inner channels 1 and 2,
Reference numeral 6 indicates an overlap welding portion between the inner channels 1 and 2 and the frame side rail 3 in the vicinity of the end portions 11 and 12 of the inner channels 1 and 2, and
Reference numeral 41 indicates a draw forming portion which is a bent portion between the base surface 22b and the side surface 22a in the spine cut portion 4 of the rear inner channel 2.

Further, a long hole 7 is formed in the front inner channel 1, and the peripheral portion of the long hole 7 and the surface of the rear inner channel 2 are joined by plug welding,
It is configured to increase the bond strength.

In the inner channel coupling structure thus configured, as shown in FIGS. 1 to 3, an end portion of the end portion 11 of the front inner channel 1 which is not welded to the outer surface 22 of the rear inner channel 2. 11 parts, that is, the side surface (12
Since the a) portion is formed so as to project toward the back cutting portion 4 of the rear inner channel 2, this extended portion for welding connection extends in the gap between the rear inner channel 2 and the frame side rail 3. By filling the gap, the side edge of the extension and the side edge of the frame side rail 3 are welded, and the extension and the side surface of the rear inner channel 2 are welded. , Front inner channel 1
Even if the end portion of is not sufficiently separated from the spine cut portion 4, the portion in the non-welded state is reduced.

Further, in this embodiment, the extension portion is formed by extending from the end portion of the front inner channel 1 toward the back cut portion 4 of the rear inner channel 2, but the end portion of the front inner channel 1 is The same applies to the case where the portion covered by the frame side rail 3 is left and the other portion is cut away in the direction away from the back cut portion 4 so that the extended portion projects in the direction of the back cut portion 4 and remains.

Further, as such a notch forming method, for example, the above-mentioned predetermined portion in the end portion 11 of the flat front inner channel 1 at the time of unfolding before press molding is cut in advance into a U-shaped notch. There are a forming method and a method in which notches are formed at the same time when press-forming with a U-shaped cross section.

Then, the end portion 11 of the front inner channel 1 and the outer surface 22 of the rear inner channel 2 which are notched in this way are formed.
By welding and joining, the welding bead 5 formed by this welding connection is applied so as to be separated from the spine cut portion 4 of the rear inner channel 2.

Thus, the spine cutting portion 4 of the rear inner channel 2, and particularly the draw forming portion 41 in which the stress is concentrated in the shape of the spine cutting portion 4 and the sheet thickness is the smallest in the press forming, is the rear inner channel 2 The outer surface 22 of the front inner channel 1 can be separated from the weld bead 5 by the welded connection with the notched end 11 of the front inner channel 1, and the weld bead 5 does not overlap or come close to each other. Cut 4
Further, it is possible to prevent the strength reduction due to the heat effect of the welding of the draw forming portion 41, and it is possible to average the stress applied to these portions 4 and 41.

Therefore, it is possible to prevent stress concentration on the spine cut portion 4 and the draw forming portion 41, so that the durability of the frame, which is a vehicle body lower skeleton member formed by coupling the inner channels 1 and 2 and the frame side rails 3, It is possible to improve the property.

Further, by adopting such a structure, the rear cutting portion 4 of the rear inner channel 2 has a shape close to a straight line, or the end 11 of the front inner channel 1 is simply separated from the back cutting portion 4. Since the gap is not present, the gap of the lap welding portion 6 does not become large at all, the welded connection at this portion can be made sufficient, and the decrease in strength can be prevented.

Further, FIGS. 4 and 5 are graphs showing the data of the experimental results of the stress distribution and the stress ratio in the joint structure of this embodiment, and the experimental results will be described below based on this graph.

First, as is clear from FIG. 4 showing the stress distribution in the vicinity of the end portions 11 and 21 of both inner channels 1 and 2, the spine cut portion 4 of the rear inner channel 2 and particularly the draw forming portion 41.
The stress concentrated on the can be averaged small.

In addition, the experimental graph shown in FIG. 5 shows that the thickness t of both inner channels 1 and 2 in FIG. 2 and the bending point of the draw forming portion 41 of the spine cut portion 4 of the rear inner channel 2 from the front inner channel 1 are shown. Notched connecting end
Plate thickness ratio (l / t) when the dimension up to 11 (that is, the distance from the spine cut portion 4 to the weld bead 5) 1 is the same, particularly when the stress at the bending point of the draw forming portion 41 is 100 Shows the change of the stress ratio with respect to, and the solid line in the figure is the plate thickness t
Is 1.2 mm, the broken line shows the change when the plate thickness t is set to 1.6 mm.

As shown in FIG. 5, the stress ratio is such that the distance 1 from the spine cut portion 4 to the weld bead 5 is equal to that of both inner channels 1,
2 tends to be saturated at about 5 times the plate thickness t, the end portion 11 of the outer surface 12 of the front inner channel 1 and the outer surface 22 of the rear inner channel 2 is welded to the outer surface 22 of the rear inner channel 2. It is desirable to form a notch so as to be separated from 4 by a distance of about 5 times the plate thickness t, but this separation distance 1 is appropriately set to an optimum dimension depending on the size and shape of each member.

Further, the durability life of the frame is generally proportional to the fifth power of the stress ratio, and in the case of the structure shown in the stress distribution of FIG. 4, the stress ratio is about 80% of that of the conventional structure shown in FIGS. 6 to 9. Thus, the structure of this invention improves the durability life by about 3 times.

In the above embodiment, the welded portion of the end portion 11 of the front inner channel 1 with the outer surface 22 of the rear inner channel 2 is notched so as to be separated from the back cut portion 4. FIG. 1 shows a structure in which the end portion 11 of the inner channel 1 and the side surface 31 of the frame side rail 3 are overlapped with each other in the direction of the back cut portion 4 of the rear inner channel 2. It can be the same as the configuration.

In addition, the vicinity of the end portion 21 of the rear inner channel 2 is provided with the spine cut portion 4.
The front inner channel 1 is cut in at a predetermined portion and the end portion 11 of the front inner channel 1 is placed outside so that they are overlapped and welded together. However, for example, the end portion 21 of the rear inner channel 2 having the opposite construction is shown. May be superposed on the outside and welded.

[Effect of device]

According to the invention, as described above, the end portion of the other inner channel fitted to the tip side of the back cutting portion of one inner channel approaches the back cutting portion at the portion covered by the frame side rail, and The uncovered portion is largely separated from the spine, and the weld bead is welded to the outer surface of one of the inner channels so that the weld bead does not reach the spine, at a portion greatly separated from the spine. It is possible to prevent stress concentration at the cut portion and reduce the void in the portion covered by the frame side rails to prevent the decrease of the joint strength. As a result, according to this invention, the durability of the frame is improved. Can be made.

[Brief description of drawings]

1 to 5 show one embodiment of the present invention. FIG. 1 is a perspective view around the connecting portion of each member, and FIG. 2 is a plan view of II of FIG. FIG. 3 is a side view of FIG. 1 viewed from III, FIG. 4 is a stress distribution diagram around the inner channel connecting portion, FIG. 5 is an experimental graph showing a stress ratio with respect to a plate thickness ratio in the same portion, and FIGS. The drawings up to the figure show a conventional example, FIG. 6 is a perspective view equivalent to FIG. 1, FIG. 7 is a plan view equivalent to FIG. 2, FIG. 8 is a side view equivalent to FIG. 3, and FIG. FIG. 4 is a stress distribution diagram corresponding to FIG. 4. 1 …… Front inner channel (one inner channel) 2 …… Rear inner channel (other inner channel) 4 …… Side cut 11,21 …… End 12,22 …… Outer surface 12a, 22a …… Side 3 …… Frame side rail 31 …… Side 32 …… End

Claims (1)

[Scope of utility model registration request] 1. A plate thickness corresponding to one end of one of a front inner channel and a rear inner channel having U-shaped cross sections which are linearly connected to each other in the longitudinal direction and the other inner channel connected to the one end. Form a back cut portion that is dropped inward, and make the portion ahead of this back cut portion thin, fit this thin formed portion inside the other inner channel, and outside these both inner channels. The frame side rails having a U-shaped cross section so as to cover a part of the outer surfaces of the inner side channels, and the frame side rails at the end portions of the other inner channel. Weld the uncovered portion to the outer surface of the narrowed portion and the frame side rails to the outer surface of both inner channels. In the inner channel coupling structure, the other end of the other inner channel is separated from the back cut portion by a larger amount than the part of the end not covered by the frame side rails, and the other inner channel. Inner channel coupling structure, wherein a portion of the end portion of the end that is not covered by the frame side rail is welded to the outer surface of the thinly formed portion in a state where a welding bead does not hang on the back cut portion. .