JP2001105023A - Tubular member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stress concentration which is added to the joint of a tubular member where members having different thickness are joined. SOLUTION: The tubular member joining a 1st and 2nd members having different thickness is formed so that two points separated in the axial direction of the tubular member exist on the joining line on a plane perpendicular to the thickness direction of the 1st and 2nd members and a part having an angle to the axial direction of the tubular member exists on the joining line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular member in which members having different thicknesses are joined.

[0002]

2. Description of the Related Art Conventionally, end portions of a plurality of members having different wall thicknesses are butted, and the butted ends are joined by welding or the like to form a tubular member.

[0003] In this type of tubular member, a joining line indicating a joining portion at an end where the members abut each other is indicated by a Japanese Utility Model Laid-Open No. 5-393.
As disclosed in 61, it is formed perpendicular to the axial direction of the tubular member.

[0004]

However, this tubular member is formed perpendicular to the axial direction of the tubular member as described above. For this reason, when the area of the cross section cut along a plane perpendicular to the axial direction is sequentially compared in the axial direction from one end of the tubular member to the other end, the one end side and the other end side of the tubular member sandwich the joining line. Changes rapidly. Therefore, as shown in FIG. 10, one end 41a of the tubular member 41 is fixed to the fixing member 43.
When the force F is applied to the other end 41b of the tubular member 41 from the direction perpendicular to the joining direction J, stress concentrates on the joint 45 having a large change in cross-sectional area. When the stress is concentrated, the joint 45 is plastically deformed. When the stress is repeatedly generated, the joint 45 is fatigued and broken. For this reason, it was not possible to increase the thickness difference of one member with respect to the other member, or to reduce the build-up of the joint portion.

[0005] An object of the present invention is to reduce stress concentration at a joint of a tubular member in which a first member and a second member having different thicknesses are joined.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, in a tubular member in which a first member and a second member having different thicknesses are joined, the first member and the second member are connected. There are two points separated in the axial direction of the tubular member on a joining line on a plane perpendicular to the thickness direction with the second member, and a portion having an angle with the axial direction of the tubular member at the joining line. It is characterized by being present.

According to a second aspect of the present invention, the first member and the second member have an area of the cross section in an axial range including the joining line in a cross section cut along a plane perpendicular to the axial direction of the tubular member. Are joined so as to change continuously.

According to a third aspect of the present invention, a joining plate formed by joining the first member and the second member each formed of a flat plate having a different thickness is formed by plastic working.

[0009]

(1) According to the first aspect of the present invention, the tubular member in which the first member and the second member having different thicknesses are joined to each other,
On a joining line indicating a joining portion on a plane perpendicular to the thickness direction of the first member and the second member, there are two separated points having an axial distance of the tubular member, and the joining member has a tubular member. Are joined so that there is a portion having an angle with the axial direction.

For this reason, when the area of the cross section cut along a plane perpendicular to the axial direction of the tubular member is taken along the axis of the tubular member, and the area is compared in the range where the joining line exists, the area changes stepwise. Since the area of the cross section perpendicular to the axial direction in the range where the joint line exists changes stepwise, when an external force having a component in the direction perpendicular to the axial direction of the tubular member is applied, the stress at the joint becomes Dispersion in the axial direction reduces the concentration of stress. This makes it possible to improve the durability of the joint. (2) In the second aspect of the present invention, the first member and the second member having different thicknesses have a continuous cross-sectional area within a range perpendicular to the axial direction of the tubular member in the axial direction included in the joining line. Joined to change. For this reason, when there is no portion where the stress is locally concentrated and an external force having a component in a direction perpendicular to the axial direction of the tubular member is applied, the stress at the joint is dispersed in the axial direction and The applied stress is reduced. Therefore, it is possible to further improve the durability of the joint as compared with the configuration of claim 1 in which the cross-sectional area changes stepwise. (3) According to the third aspect of the present invention, the first member and the second member made of a plate material are joined to form a joining plate, and the joining plate is subjected to plastic working to form a tubular member. Thereby, in addition to the above-mentioned effects, it is possible to reduce the stress applied to the joint when the joining plate is subjected to plastic working.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

(First Embodiment) A first embodiment will be described with reference to the drawings.

FIG. 1 shows an overall configuration diagram of a suspension 1 using a tubular member according to an embodiment of the present invention.

The suspension 1 has a carrier 3 for supporting a tire 2. The carrier 3 includes one end of the first arm 4 on the upper side, and one end of the second arm 5 on the lower side.
It is supported at one end of the arm 6. Each arm 4, 5, 6
Is connected to a vehicle body (not shown). The second arm 5 and the third arm 6 are arranged so as to be aligned in the front-rear direction of the vehicle body. The suspension 1 is provided with a strut 7 for restricting the movement of the tire 2 in the vertical direction with respect to the vehicle body. The upper end of the strut 7
The lower end is connected to the connecting portion 8 of the third arm 6.

FIG. 2 is a perspective view of the third arm 6.

The third arm 6 has a substantially cylindrical pipe 11.
A carrier connecting portion 12 connected to the carrier 3 at an end of the pipe 11, a vehicle body connecting portion 13 connected to the vehicle body,
Connection 8 supporting strut 7 approximately in the middle of pipe 11
And formed. The pipe 11 has a second member 15 having a vehicle body connection portion and a third member 1 having a carrier connection portion 12 centered on the first member 14 provided with the connection portion 8.
6 and three members.

The first member 14 is formed of a member thicker than the second member 15 and the third member 16 to receive the load of the vehicle body from the strut 7 at the connecting portion 8. The first member 14 is joined to each of the second member 15 and the third member 16 by welding.

The boundaries between the first member 14 and the second member 15 and between the first member 14 and the third member 16 are defined by the members 14, 15, 1
The joining lines 17 and 18 shown on the plane perpendicular to the thickness direction of 6 are:
The pipes 11, which are tubular members, are joined so that there are two points on the joining lines 17 and 18 that are spaced apart in the axial direction, and that the joining lines have a portion that has an angle with the axial direction.

Along the joining lines 17 and 18, they are separated in the axial direction.
The existence of the two points indicates that the joining line portion is displaced in the circumferential direction and is displaced in the axial direction, or the joining line portion is displaced in the axial direction only with respect to a point on a part of the joining lines 17 and 18. Is to exist. Also, the joining lines 17 and 1
The fact that a portion having an angle with the axial direction of the pipe 11 exists in 8 means that the joining lines 17 and 18 are not constituted only by the joining lines 17 and 18 parallel to the axial direction of the pipe 11.

Also, there are two axially separated points on the joining lines 17 and 18 of the pipe 11, and the joining lines 17 and 18
Is present in the pipe 11 in which the first member 14 and the second member 15 and the first member 14 and the third member 16 are joined to each other.
4 and the second member 15, and the joining lines 17 and 18 on the surface perpendicular to the thickness direction of the first member 14 and the third member 16
Having a non-perpendicular portion that is not perpendicular to the axial direction of
7 and 18 have non-parallel portions that are not parallel to the axial direction of the pipe 11.

With this configuration, the pipe 11
Since the ratio of the first member 14 and the second member 15 or the ratio of the first member 14 and the third member 16 to the cross section perpendicular to the axial direction changes, the area of the cross section is compared within the range where the joining lines 17 and 18 exist. Then, the area changes stepwise.

In the present embodiment, the joining lines 17, 18 are joined so as to have inclined portions 17a, 18a inclined in the axial direction of the pipe 11. For this reason, comparing the area of the cross section perpendicular to the axial direction of the pipe 11 along the axis of the pipe 11, the cross section shows that the inclined portions 17 a, 18
It is formed so as to gradually change in the axial direction of the pipe 11 in a range including a.

Further, the first member 14 and the second member 15 and the first member 14 and the third member 16 are formed in a cross section taken along a plane perpendicular to the axial direction of the pipe 11 in an axial direction included in the joining lines 17 and 18. In the range, they are joined so as to change continuously. Therefore, the joining lines 17 and 18 do not have a portion perpendicular to the axial direction of the pipe 11 and do not have two joining line portions that are parallel to the axial direction at the same position in the axial direction.

As shown in FIG. 3, the pipe 11 includes a first steel plate 14a forming the first member 14 and a second steel plate 15a forming the second member 15 having a smaller thickness than the first steel plate 14a.
And a third steel plate 16a constituting the third member 16 having a thickness smaller than that of the first steel plate 14a, are joined by welding to form a joining plate 19, and the joining plate 19 is formed by plastic working. It is rolled and formed into a cylindrical shape by press working, which is one of the methods. First steel plate 14a and second steel plate 15
a and the welding of the steel plates having different thicknesses with the third steel plate 16a,
It is welded by laser welding as disclosed in JP-A-7-195187.

The end of the first steel plate 14a joined to the second steel plate 15a and the third steel plate 16a is formed so as to be inclined with respect to the axial direction of the pipe 11. The end of the second steel plate 15a opposite to the end to which the vehicle body connection portion 13 is connected is inclined so as to match the inclination of one end of the first steel plate 14a. The end of the third steel plate 16a opposite to the end to which the carrier connection portion 14 is connected is inclined so as to match the inclination of the other end of the first steel plate 14a.

For this reason, when the area of the cross section perpendicular to the axial direction of the pipe 11 is compared along the axis, it changes from one end of the pipe 11 to the other end in a range including the inclined portion 17a. For example, comparing pipes 11 of FIG. 2 at predetermined intervals from the first steel plate 14a side to the second steel plate 15a side, and comparing cross sections cut along aa ′ to ee ′ along an axis, The area changes stepwise as shown in FIGS.

FIG. 4A shows the cross section of the pipe 11.
Since the portion occupied by the thin second steel plate 15a is small,
The area is large. FIG. 4B is a cross section of the second steel plate 15a side from FIG. 4A. At this time, since the portion occupied by the second steel plate 15a is large, the area of FIG. 4B is smaller than that of FIG. 4A. In this way, as sections are taken one after another, the portion occupied by the second steel plate 15a gradually increases, and the area of the pipe 11 decreases.

The stress concentration occurs in a place where the change in the area of the cross section is large. The stress generated at a place where the cross-sectional area change is large is the ratio of the thickness of each member to the stress generated at that place when there is no change in cross-section, and the rate of change of the cross-sectional area with respect to the thickness of the thinner member. Multiplied by the stress concentration coefficient calculated from Therefore, to reduce the stress concentration with a member having a predetermined thickness is to reduce the rate of change of the cross-sectional area.

As described above, the fact that the welded portion between the first steel plate 14a and the second steel plate 15a is the inclined portion 17a that is inclined with respect to the axial direction of the pipe 11 means that the inclined portion 17a of the pipe 11 There are two points separated in the axial direction of the pipe 11 on the joining line 17 including
Is present, which is based on reducing the rate of change of the cross-sectional area.

Further, the first steel plate 14a and the second steel plate 15a have a continuous cross-sectional area in the axial direction including the joining line 17 in a cross section cut along a plane perpendicular to the axial direction of the pipe 11. Joined to change. For this reason, the joining line 17 does not include a portion perpendicular to the axial direction of the pipe 11 and does not include two joining line portions that are parallel to the axial direction at the same position in the axial direction. As a result, there is no portion where the area of the cross section changes suddenly, and there is no portion where the stress concentration is locally concentrated at the joint.

Similarly, at the other end, the first steel plate 14a and the third steel plate 16a are used to reduce the stress concentration at the joint.
That the welded portion of the pipe 11 is inclined with respect to the axial direction of the pipe 11.
Is present at the joint line 18 including two points separated in the axial direction of the pipe 11 and the joint line 18 has a portion having an angle with respect to the axial direction of the pipe 11. Is reduced.

The fact that the first steel plate 14a and the third steel plate 16a are inclined portions 18a which are always inclined with respect to the axial direction of the pipe 11 means that the joining line 18 is perpendicular to the axial direction of the pipe 11. Is not present, and two joining line portions that are parallel to the axial direction at the same position in the axial direction do not exist, and the first steel plate 14a and the third steel plate 16a This means that the cross section cut along a plane perpendicular to the direction is bonded so that the area of the cross section continuously changes in the axial direction including the bonding line 18.

The shapes of these joining lines 17 and 18 are appropriately changed depending on the force applied to the members and the like.
The optimum value obtained by experiment or calculation is adopted.

A vehicle connecting portion 13 and a carrier connecting portion 12 formed by performing a punching process, a pressing process, or the like are joined to an end of the pipe 11 thus formed by welding. The third arm 6 is formed by joining the joining portion 8 to a portion constituted by members by welding.

The third arm 6 has a joining line 17 between the first member 14 and the second member 15 and the first member 14 and the third member 16,
It is configured such that two points separated from each other in the axial direction of the pipe 11 are present on the pipe 18, and a portion having an angle with the axial direction of the pipe 11 is present on the joining lines 17 and 18. Further, the third arm 6 includes the first member 14, the second member 15, and the first member 1
The fourth member 16 and the third member 16 are joined such that the area of the section continuously changes in the axial direction including the joining lines 17 and 18 in a section cut along a plane perpendicular to the axial direction of the pipe 11. ing. That is, the third arm 6 does not have an abruptly changing portion in which the area of the cross section perpendicular to the axial direction of the third arm 6 changes abruptly in the axial direction, and the third arm 6 changes gradually in the axial direction of the pipe 11 continuously. It is configured as follows.

Thus, when the third arm 6 receives the load of the vehicle body with the carrier connecting portion 12 and the vehicle body connecting portion 13 as fulcrums and the connecting portion 8 as a point of application, a bending stress is applied to the third arm 6. Even in this case, the concentration of stress at the connection between the first member 14 and the second member 15 and the connection between the first member 14 and the third member 16 can be continuously dispersed in the axial direction of the pipe 11.

For example, the pipe 11 is placed on the joining lines 17 and 18.
There are two points separated in the axial direction of
The first member 14 and the second member 15 and the first member 14 and the third member 16 are joined so that a portion having an angle with the axial direction of the pipe 11 exists at 8. Consider a case where the pipe 11 is configured such that a vertical portion perpendicular to the axial direction of the pipe 11 exists. In this case, the pipe 11 is compared along the axis within a range included in the joining lines 17 and 18 in a section perpendicular to the axial direction of the pipe 11. The area of the cross section greatly changes at one end and the other end of the vertical portion of the joining lines 17 and 18. For this reason, the stress applied to the vertical portions of the joining lines 17 and 18 is larger than the stress at other portions of the joining lines 17 and 18, and the vertical portions of the joining lines 17 and 18 are less likely to be fatigued due to the concentration of stress than the other portions. growing. However, in the present embodiment, the area of the cross section perpendicular to the axial direction of the pipe 11 is formed so as to change continuously in a range including the joining lines 17 and 18 in the cross section and not change in other portions. Therefore, there is no portion where the stress is locally concentrated, and the fatigue of only the vertical portion due to the concentration of the stress is reduced.

The joining lines 17 and 18 are formed so that there is no portion perpendicular to the axial end of the pipe 11 of the joining plate 19. For this reason, when pressing the joint plate 19, stress concentration at the joint can be prevented.

(Second Embodiment) A second embodiment will be described with reference to the drawings.

FIG. 5 is a perspective view of a tubular member formed by pressing a joining plate obtained by joining steel plates having different thicknesses.

The pipe 51 as the tubular member is formed by a first
A member 52 and a second member 53 having a smaller thickness than the first member 52
And is formed from First member 52 and second member 53
Are joined by welding. A joining line 54 indicating a joint between the first member 52 and the second member 53 on a plane perpendicular to the thickness direction of each member 52, 53 is formed by a pipe 51 on the joining line 54.
Are formed in such a manner that there are two points separated in the axial direction, and that the joining line 54 has a portion having an angle with the axial direction. Given that such two points are on the joining line 54 and that there is a portion of the joining line 54 that has an angle with the axial direction of the pipe 11, there is a portion of the joining line 54 that is not perpendicular to the axial direction of the pipe 51. There is a portion that is not parallel to the axial direction of the pipe 51. Joining line 54 of this pipe 51
Is an inclined portion 55 that is not perpendicular to the axial direction of the pipe 51 but is inclined, and a vertical portion 56a that is perpendicular to the axial direction of the pipe 51,
It is formed to have 56b. For this reason, the area of the cross section perpendicular to the axial direction of the pipe 51 is
Is gradually changed in the axial direction of the pipe 51 in the range including

FIG. 6 is a front view of a bonded plate obtained by bonding steel plates having different thicknesses.

As shown in FIG. 6, the pipe 51 is made of a flat plate of a first steel plate 52a forming the first member 52 and a second steel plate 53a forming the second member 53 thinner than the first steel plate 52a. Are joined by welding to form a joining plate 57, and the joining plate 57 is formed into a cylindrical shape by rolling by press working, which is one method of plastic working.
The first steel plate 52a and the second steel plate 53a are welded by the same laser welding as in the first embodiment when the steel plates having different thicknesses are welded.

The first steel plate 51a to be joined to the second steel plate 53a
Are formed such that the center of the end is inclined with respect to the axial direction of the pipe 51, and both ends of the center of the end are formed perpendicular to the axial direction of the pipe 52. ing. Similarly, the second steel plate 53a to be joined to the first steel plate 52a
Is formed so as to abut the end of the first steel plate 52a.

For this reason, the first steel plate 52a and the second steel plate 53
As in the first embodiment, the cross-sectional area of the welded portion 54a is not limited to the range including the inclined portion 55 that is not perpendicular to the axial direction of the pipe 51 in the cross-section perpendicular to the axial direction of the pipe 51. Is gradually changing.

In the pipe 51, the fact that the inclined portion 55 that is not perpendicular to the axial direction of the pipe 51 is present in the welded portion 54a of the first member 52 and the second member 53 means that the weld line 54a of the pipe 11 includes the welded portion 54a. The pipe 51 is formed so that there are two points separated in the axial direction of the pipe 51, and the joining line 54 has a portion having an angle with the axial direction. This allows
The cross-sectional area of a cross section perpendicular to the axial direction of the pipe 51
When the cross-sectional area is compared along the range where the joining line 54 exists, the sectional area changes stepwise. For this reason, the portion where the stress on the joining line 54 concentrates is reduced, and when the bending stress is applied to the pipe 51, the concentration of the stress applied to the joining portion 54 can be dispersed in the axial direction.

In the first and second embodiments, the technique of forming the pipe 11 or the pipe 51 as a tubular member by pressing a bonding plate obtained by bonding a plurality of steel plates having different thicknesses has been described. However, as shown in FIG. 7, it is also possible to connect the first pipe 22 and the second pipe 23 having different thicknesses cut so as to be inclined in a predetermined direction with respect to the axial direction of the pipe 21. is there.

Thus, it is possible to form a pipe, which is a tubular member in which members having different thicknesses are joined, without performing processing such as pressing.

Further, in the above-described embodiment, the shape of the joining line indicating the joining portion of the pipes as the tubular members is formed as a straight line. However, as shown in FIGS. The welded portion 34a of the second steel plate 32 and the second steel plate 33 is joined so as to have a SIN curve to form the joined plate 31, and the pipe 35 can be formed by press working.

The fact that the welded portion 34a is curved means that the first steel plate 32 and the second steel plate 33 are cut along a plane perpendicular to the axial direction of the pipe in the axial direction including the joining line. Are joined so that the area of each of them continuously changes.

Although the joining line is a SIN curve in the present embodiment, it can be changed to an optimum curve obtained by experiment or calculation as appropriate, for example.

Thus, in addition to obtaining the same effects as those of the above-described embodiment, there is no place where the sectional area of the pipe changes abruptly because it is formed by a curve, and the direction in which the pipe is installed is Regardless of the direction of the applied force, the concentration of stress at the joint can be reduced. Furthermore, if the pipe is formed as a curve, there is no place where the cross-sectional area of the pipe changes abruptly, so that it is not necessary to design in consideration of the local occurrence of a stress concentration portion.

It should be noted that the present invention is not limited to the above-described embodiment, and can be carried out as follows, with appropriate modifications without departing from the spirit of the invention. (1) In the above embodiment, the joining plate is pressed to form a cylindrical pipe, but after the pressing, the ends of the joining plate parallel to the pipe axial direction can be joined by welding. It is. (2) In the above embodiment, a cylindrical pipe is disclosed as an example of the tubular member, but a similar effect can be obtained with a square pipe or the like. Further, although the tubular member is applied to the suspension arm, it can be used for an instrument panel reinforcement or the like. (3) In the above embodiment, a straight line and a curve have been disclosed as examples of the joining line. However, the joining line may be configured to have a zigzag shape or a square wave.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing the overall configuration of a suspension.

FIG. 2 is a perspective view of a third arm.

FIG. 3 is a front view of a joining plate constituting the pipe.

FIG. 4 is a sectional view of a pipe cut at a predetermined interval in an axial direction.

FIG. 5 is a perspective view showing a pipe.

FIG. 6 is a front view of a joining plate.

FIG. 7 is a perspective view showing a pipe.

FIG. 8 is a front view of a joining plate in which joining lines are formed by curves.

FIG. 9 is a configuration diagram of a pipe formed by pressing the bonding plate of FIG. 5;

FIG. 10 is a view showing the operation of a conventional tubular member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Suspension 2 ... Tire 3 ... Carrier 4 ... 1st arm 5 ... 2nd arm 6 ... 3rd arm 7 ... Strut 8 ... Joint part 11 ...・ Pipe 12 ・ ・ ・ Carrier connection part 13 ・ ・ ・ Vehicle connection part 14 ・ ・ ・ First member 14a ・ ・ ・ First steel plate constituting first member 15 ・ ・ ・ Second member 15a ・ ・ ・ Second member , A third member 16a, a third steel plate constituting a third member 17, 18, a joining line 17a, 18a, a welding portion 19, a joining plate 21, .... Pipe 22 ... first pipe 23 ... second pipe 31 ... joining plate 32 ... first steel plate 33 ... second steel plate 34 ... joining line 34 ... · Welded part a 35 ··· Pipe 41 ··· Tubular member 41a ··· One end of tubular member 41b ... the other end of the tubular member 43 ... fixing member 45 ... joining part 51 ... pipe 52 ... first member 52a ... first steel plate 53 ... second member 53a ... 2nd steel plate 54 ... joining line 54a ... welding part 55 ... inclined part 56a, 56b ... vertical part 57 ... joining plate

Claims (3)

[Claims] 1. A tubular member in which a first member and a second member having different thicknesses are joined to each other, wherein the tubular member is placed on a joining line on a plane perpendicular to a thickness direction of the first member and the second member. A tubular member, wherein two points separated in the axial direction are present, and a portion having an angle with the axial direction of the tubular member is present at the joining line. 2. The cross section of the first member and the second member, which has a cross section cut along a plane perpendicular to the axial direction of the tubular member, has an area of the cross section continuously in an axial range including the joining line. 2. The tubular member of claim 1, wherein the tubular member is variably connected. 3. The method according to claim 1, wherein a joining plate formed by joining the first member and the second member formed of flat plates having different thicknesses is formed by plastic working.
2, tubular member.