JP2000096769A - Double end support beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double end support beam which causes no problem even when deflection occurs. SOLUTION: A double end support beam 1 of which the beam height changes so that a section modulus lessens toward the central part from the opposite end parts is provided by reducing the lower side 5 of the double end support beam 1 by a length being equal to or larger than the deflection length of each part thereof. This double end support beam is constituted of an upper-side flange 2, a lower-side flange 3 and a web 4 connecting them and has a practically T-shaped section, for instance, and it has opposite end parts (a) of a prescribed length having a fixed sectional shape, varied section parts (b) wherein the web 4 changes to be shorter continuously so that the lower side 5 of the beam be reduced by the length being equal to or larger than the deflection length of each part, parts (c) wherein the thickness of the lower-side flange 3 changes to be smaller continuously and an intermediate part (d) of a prescribed length having a fixed sectional shape of a small section modulus, toward the central part from the opposite end parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a both-end supporting beam having a continuously changing cross-sectional shape,
The present invention relates to a beam supported at both ends which does not cause adverse effects due to deflection.

[0002]

2. Description of the Related Art Conventionally, both-end supporting beams are mainly manufactured from a general-purpose steel material having a constant cross-sectional shape such as a rectangular steel pipe or an H-section steel in view of its mechanical strength and cost. Such a steel beam supported at both ends causes deflection in the central portion due to its own weight. This deflection increases as the length of the beam increases, and causes various problems depending on the application.

FIG. 15 is a schematic view of a wing body type truck. Wing body type truck 15
In one loading platform, a center beam 154 is provided between the upper center of the front torii 153 and the upper center of the rear gate 156, and the center beam 154 is provided substantially on the left and right sides of the center beam 154. A cargo box 152 mainly including a substantially L-shaped door (hereinafter, referred to as “wing 155”).
Is provided. The packing box 152 is designed such that the inside of the packing box 152 is made as large as possible to transport a large amount of cargo. Therefore, the materials and shapes of the constituent members are appropriately selected so as not to cause protrusions and bending inside the packing box 152.

Among these components, the center beam 154 used for the packing box 152 of the wing body type truck 151 generally has a side length of 125 mm.
A square steel pipe having a square cross section in the range of up to 75 mm and having a constant cross section is used.

However, in practice, the center beam 154 is easily bent by its own weight, and the generated bending reduces the volume in the packing box 152. Such deflection causes a problem that the load cannot be sufficiently loaded without the deflection. Especially for long body trucks, the center beam 1
54 becomes longer, and the deflection at the center thereof becomes larger.
For example, FIG. 14 shows a front view of an example of a conventional center beam 144 using a square steel pipe having a square cross section having a side length of 100 mm. As shown in FIG. 14, since the center beam 144 projects downward by the bent length L, the cargo hits the projecting portion, and if there is no deflection, the loadable cargo cannot be sufficiently loaded.

[0006]

In order to solve such a problem, conventionally, the deflection length has been shortened by increasing the section modulus of each portion of the center beam, particularly the section modulus of the support portions at both ends. I was For example, the deflection has been reduced by welding a flat plate to the lower surfaces of both end support portions of the center beam, or by processing the square steel material of both end support portions so as to expand. However, such a method further increases the outer dimensions of the support portions at both ends of the center beam,
It was not possible to solve the problem that the space volume inside the packing box was reduced and the load capacity was reduced. Also, by cutting out the lower part of the center beam of the bent part or welding a small diameter square steel material to the bent part,
Attempts have also been made to reduce the deflection length by reducing its own weight. However, in any case, the processing cost due to the notch or welding increases, and particularly in the case of welding, problems such as thermal deformation and corrosion resistance are added.

On the other hand, if the center beam becomes longer, the deflection due to its own weight becomes larger. Therefore, in order to reduce its own weight, the center beam has been manufactured from a lightweight material.

However, a lightweight material such as aluminum has a smaller Young's modulus than a conventionally used steel material. Therefore, in order to produce a center beam having the same mechanical strength as that of a conventional material, the section modulus is reduced. Must be increased. Therefore, a center beam using a lightweight material has a large outer dimension and a reduced space volume inside the packing box, so that the amount of cargo that can be loaded is reduced.

In order to solve these problems, the present invention provides:
It is an object of the present invention to provide a support beam at both ends which does not cause a problem even if deflection occurs.

[0010]

According to a first aspect of the present invention, there is provided a both-end supporting beam whose beam height is changed so that the section modulus becomes smaller from both ends to a center.
It is characterized in that the lower side of the both-end supporting beam is reduced by a length equal to or greater than the bending length of each portion of the both-end supporting beam. According to the present invention, since the beam height changes so that the section modulus becomes smaller from both ends to the center of the beam, each portion of the beam supported at both ends has substantially equal strength. As a result, the bending moment of each part of the beam is reduced, and the deflection length of the beam can be reduced. In the present invention, the upper side of the both-end supporting beam is not changed at all, and its lower side is reduced by a length equal to or more than the bending length of each part, so that it was used as a both-end supporting beam for transportation equipment, for example. In this case, the deflection generated in each part of the beam does not come into contact with the cargo, so that there is no problem that the load is reduced. In addition, since it has the above-mentioned cross-sectional shape which is substantially equal in strength, the strength of the beam is not reduced. Furthermore, since the section modulus is changed so as to decrease from both end portions to the center portion, the weight of the beam itself can be reduced, and the weight of the middle portion where bending is most likely to occur can be reduced. The deflection length can be reduced.

According to a second aspect of the present invention, in the two-end supporting beam according to the first aspect, the both-end supporting beam comprises an upper surface flange, a lower surface flange, and a web connecting the upper surface flange and the lower surface flange. It has a substantially T-shaped cross-sectional shape, and from both ends to a central portion, both ends of a predetermined length having a constant cross-sectional shape, and the lower side of the both ends support beam, the two ends support beam of each part A variable cross-section where the web continuously changes so as to be reduced by a length equal to or greater than the flexure length, a portion where the thickness of the lower surface flange changes continuously and thinly, and a constant cross-sectional shape with a small cross-section modulus And an intermediate portion having a predetermined length. According to the present invention, the cross-sectional shape of each portion from the both ends of the beam toward the central portion is set to a substantially T-shaped cross-sectional shape arranged at a position away from the neutral axis of the cross-section of the both-end supporting beam. Even if the both-ends support beam has a cross-sectional shape changed so that the cross-sectional modulus decreases from the portion to the central portion, the cross-sectional modulus is adjusted so that the mechanical strength of the beam can be maintained. As a result, the strength of the beam can be maintained even if the lower side of the support beam at both ends is reduced by a length equal to or greater than the bending length of each part. Also,
Since the lower side of the obtained both-end supporting beam is reduced by a length equal to or longer than the bending length, there is no adverse effect due to the bending.

A third aspect of the present invention is characterized in that, in the two-end supporting beam according to the first or second aspect, the both-end supporting beam is formed of a seamless material. According to the present invention, since the both-end supporting beam is formed of a seamless material, there is little adverse effect such as deformation or corrosion which is likely to occur by welding or bolting.

According to a fourth aspect of the present invention, in the two-end supporting beam according to any one of the first to third aspects, the both-end supporting beam is formed by a variable cross-section extrusion method. Having. According to the present invention, the cross-sectional shape of the both-end supporting beam can be easily changed by the variable cross-section extrusion method performed by controlling a plurality of dies. It can be integrally molded in the process. It is also preferable in terms of simplification of the manufacturing process and reduction of the manufacturing cost as compared with a conventional both-end supporting beam formed by welding, bolting, cutting, or the like.

A fifth aspect of the present invention is characterized in that, in the two-end supporting beam according to any one of the first to fourth aspects, the both-end supporting beam is formed of aluminum or an aluminum alloy. . According to the present invention, since aluminum or an aluminum alloy, which is a lightweight material, is used, the weight can be reduced as compared with a conventionally used both-end supporting beam using a steel material. Further, since the beam has the above-described cross-sectional shape so that the beam has substantially equal strength, the mechanical strength of the beam does not decrease. Therefore, for example, when used as a support beam at both ends for transportation equipment, the length of flexure generated at the middle portion of the beam can be reduced, and the beam does not come into contact with the cargo, and the load capacity is reduced. It is possible to reduce the weight of the transportation equipment without causing any trouble.

According to a sixth aspect of the present invention, there is provided the beam of any one of the first to fifth aspects, wherein the center beam is used for a packing box of a wing body type truck. Have. According to the present invention, since the above-described beam is used for the center beam of the packing box of the wing body type truck, the space volume in the packing box is not reduced even if the center beam is bent. As a result, the load of the wing body type truck is not reduced. In addition, since the beam has a cross-sectional shape changed so that the cross-sectional modulus decreases continuously or stepwise from both end portions to the center portion, the beam has a substantially equal strength, so that the constituent material of the center portion can be reduced, especially the center portion. The beam can be reduced in weight.

[0016]

Next, an example of an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front view showing an example of a beam supported at both ends of the present invention, specifically, a center beam used for a packing box of a wing body type truck. FIG. 2 to FIG.
It is sectional drawing which shows the cross-sectional shape of each part of the both ends support beam 1 shown in FIG. Here, FIG. 2 shows an AA cross section, and FIG.
FIG. 4 shows a cross section taken along line CC of FIG. The both-end supporting beam 1 has an upper flange 2, a lower flange 3, a web 4 connecting the upper flange 2 and the lower flange 3, and a drooping portion 2 a protruding downward from both ends of the upper flange 2. It has a U-shaped cross section. Then, from both ends O and O 'points to the central S point,
Both end portions of a predetermined length having a constant cross-sectional shape (region a,
a ′), a variable cross-section portion (regions b and b ′) where the web 4 continuously changes so as to reduce the lower side 5 side of the beam 1 by a length equal to or greater than the bending length, and the thickness of the lower surface flange 3 (Regions c and c ′) and an intermediate portion (region d) of a predetermined length having a constant sectional shape with a small sectional modulus. The support beam 1 at both ends of such a structure has a structure in which the lower side 5 of the intermediate portion is reduced, in other words, a structure in which the lower side 5 of the intermediate portion is concave, and each portion in the longitudinal direction has approximately equal strength. Has become.

Next, the sectional shape of each part of the both-end supporting beam 1 shown in FIG. 1 will be described.

As shown in FIG. 2, in a region a between an end point O of the both-end supporting beam 1 and a point P separated by a predetermined distance from the point O, the sectional height of the beam 1 is H1. , The length of the web 4 is h1, the width of the upper surface flange 2 is W, the width of the lower surface flange 3 is w, the length of the hanging portion 2a is L, and the thickness of the lower surface flange 3 is a substantially T-shaped constant cross section. The shape is shown. This region a needs to have sufficient mechanical strength to support the beam 1 and therefore has a cross-sectional shape with a large cross-sectional modulus.

In a region b between the point P and the point Q further entering the center of the beam, as shown in FIG. 3, the width of the upper flange 2 is W and the width of the lower flange 3 is w. , The length of the hanging part 2a is L, the thickness of the lower surface flange 3 is a substantially T-shaped cross-sectional shape of t1, and Q
Between the points, a variable cross-sectional shape is shown in which the web length continuously decreases from h1 to h2. As a result, beam 1
Is continuously shortened from H1 to H2 between the point P and the point Q. In this region b, the beam is made to have substantially the same strength, and the lower side 5 side is reduced by a length equal to or more than the bending length of each part without changing the upper side of the beam, and the sectional shape thereof is changed. I have.

In a region c between the point Q and a point R slightly entering the center of the beam 1, as shown in FIG. 4, the length of the web 4 is h2, and the width of the upper flange 2 is Is W, the width of the lower surface flange 3 is w, the length of the hanging portion 2a is a substantially T-shaped cross section, and the thickness of the lower surface flange 3 is changed from t1 to t2 between the points Q and R. It shows a variable cross-sectional shape that becomes continuously shorter. as a result,
The cross section height of the beam 1 is between H2 and H
It becomes 3 continuously short. This region c has a cross-sectional shape so as to reduce the weight of the beam so as to be approximately equal in strength and to minimize the deflection due to its own weight as much as possible.

In a region d between the point R and the point R 'of the beam 1, as shown in FIG. 4, the section height of the beam 1 is H3, the length of the web 4 is h2, and The width of the lower surface flange 3 is w, the length of the hanging portion 2a is L, and the thickness of the lower surface flange 3 is t2. This region d has a cross-sectional shape that can maintain at least the mechanical strength enough to withstand the shearing force.

As shown in FIG. 1, the both-end supporting beam 1 has a symmetrical shape with respect to the center point S. Therefore, the region a 'from the point O' to the point P ', the region b' from the point P 'to the point Q', and the region c 'from the point Q' to the point R 'are the above-mentioned regions a, b, It has the same dimensions and the same cross-sectional structure as region c.

Therefore, according to the both-end supporting beam 1 shown in FIG. 1, the cross-sectional shape of the upper half of the beam has the same shape in each part, but the cross-sectional shape of the lower half is P Region b between point and point Q and point P ′ to Q ′
By changing the length of the web 4 from h1 to h2 in the region b ′ between the points, the sectional height of the beam 1 is changed from H1 to H2.
Shows the changed cross-sectional structure. Further, the thickness of the lower surface flange 3 changes from t1 to t2 in a region c between the point Q and the point R and in a region c 'between the point Q' and the point R '. 2 shows a cross-sectional structure changed from H3 to H3.

Such a cross-sectional structure is appropriately set to a preferable size in consideration of the degree of the bending length of each part when the obtained both-end supporting beam 1 is actually bent and the strength of the beam.

The sectional structure of the both-end supporting beam 1 is a structure in which the section modulus is changed in proportion to the bending moment of each part of the double-sided supporting beam. , And the bending moment is small at the center of the beam, so that it is theoretically most preferable to reduce the section modulus. By adopting such a cross-sectional structure, the beam can have equal strength over the respective portions of the beam, and the beam 1 at both ends is not bent.

However, when both ends of the beam are provided with wings on both sides thereof, such as a center beam used for a packing box of a wing body type truck, a shear force acts on the center beam. Therefore,
Normally, it is necessary that even a central portion of a beam having a small bending moment has a sectional modulus capable of withstanding an applied shearing force. For this reason, it is preferable that the cross-sectional shape has at least a cross-sectional coefficient enough to withstand the shearing force and a substantially equal strength. In the present invention, the deflection length of the beam is reduced by adopting a structure having a cross-sectional shape that is changed continuously or stepwise from both end portions to the center portion so that the cross-sectional modulus is reduced from the both end portions to the approximately equal strength. In addition, the weight of the beam can be reduced without reducing the mechanical strength of the beam. Also,
By forming the beam from a lightweight material such as aluminum, the weight of the beam can be reduced, so that a large deflection does not occur even in a cross-sectional shape sufficient to withstand the shearing force.

FIG. 5 is a front view showing the state of deflection of the both-end supporting beam 1 shown in FIG. As shown in FIG. 1, the both-end supporting beam 1 of the present invention has a sectional height H1 → H2 → H3 so as to reduce the sectional modulus from both end portions to the central portion. Has a section modulus at least enough to withstand the shearing force and is substantially equal in strength. Furthermore, since the lower side 5 side of the intermediate portion of the beam 1 is reduced by the actual flexing length x1, the flexing beam 1 projects below the extension line Z of the support portion at both ends of the beam. Can be prevented. Therefore, from the lower side 5 of the beam 1 when there is no deflection,
It is preferable that the length x2 of the beam 1 to the extension line Z of the support portion at both ends is equal to or longer than the length x1 at which the obtained beam 1 actually bends. The length x2 to be reduced at this time is appropriately set according to the actually generated flexure length x1.

Therefore, the beam supported at both ends of the present invention is the same as that of FIG.
As shown in the center beam manufactured by the conventional rectangular steel pipe shown in FIG. 1, since the bent portion does not protrude below the extension line z of the support portion at both ends of the center beam, the cargo can be loaded even by the bending. The amount is not reduced. In addition, since approximately equal strength is maintained,
It does not reduce the mechanical strength of the beam.

The both-end supporting beam 1 can be formed by a variable cross-section extrusion method. Regarding the variable cross-section extrusion method, an example of forming the both-end supporting beam shown in FIGS. 1 to 4 will be described below. In addition, the present applicant has already applied for several patents prior to the present application, for example, Japanese Patent Application Laid-Open No. 8-1922.
It can also be extruded by the method disclosed in JP-A-21.

The both-end supporting beam 1 is, for example, combined with two extrusion dies 10, 11 as shown in FIGS. 6 and 8 so that the extrusion holes 14, 30 of the dies 10, 11 overlap each other. It is formed by extruding an extruded material from. By changing the positional relationship between the two extrusion dies 10, 11, the overlapping portion of the extrusion holes 14, 30 is changed, so that the cross-sectional shape of the extruded both-end support beam can be changed.

More specifically, a stationary die 10 as shown in FIG. 6 and a movable die 11 (FIG. 8) movably engaged in a guide hole 22 (see FIG. 7) of the stationary die 10.
See ) Constitutes an extrusion die for variable section extrusion.

As shown in FIGS. 6 and 7, the fixed die 10 has an extrusion hole 14 formed in the center thereof.
The extrusion hole 14 of the fixed die 10 is, as shown in FIG.
An upper surface flange forming hole 15 having the same shape and dimensions as the upper surface flange 2 and the hanging portion 2a of the both-end supporting beam 1 to be formed, and a web forming hole 16 extending from a central portion of the upper surface flange forming hole 15 in a direction orthogonal thereto. And a lower surface flange communication hole 17 formed at the other end of the web forming hole 16. Here, the length of the web forming hole 16 is formed to be the same as the length h2 of the web 4 shown in FIGS.
The width w1 of 7 is formed to be equal to or larger than a lower surface flange forming hole described later.

The fixed die 10 is formed in the shape of a substantially rectangular plate with hot tool steel. The upper surface 12 of the fixed die 10 is located on the side of the container 21 in which the extruded material is stored. Around the extrusion hole 14 located at the center of the fixed die 10, a flow for smoothly guiding the extruded material to the extruded hole 14 is provided. In the road, a concave portion 13 is formed which is narrowed inward from the upper surface 12 side. In particular, the web forming holes 16
Are formed on both sides thereof to guide the extruded material smoothly into the web forming hole 16. Further, the upper surface 12 of the fixed die 10 has a container 21 projecting therefrom.
Is formed with a circular step portion 19 to be fitted to the lower surface of
Inside the step 19, the inside of the container 21 and the recess 13
And a large-diameter guide portion 20 that communicates with.

Further, as shown in FIG.
A guide hole 22 that extends in a direction parallel to the web forming hole 16 and penetrates through the fixed die 10 and in which the movable die 11 is movably accommodated is formed in a central portion of the inside. A guide wall 23 for guiding the side surface 31 of the movable die 11 slidably and densely is formed on the side surface of the guide hole 22.

As shown in FIG. 8, the moving die 11 has an extrusion hole 30 formed in the center thereof. As shown in FIG. 10, the extrusion hole 30 of the moving die 11 has a lower flange forming hole 27 having the same shape and dimensions as the lower flange 3 of the both-end supporting beam 1 to be formed, and a central portion of the lower flange forming hole 27. And a web forming hole 28 extending in a direction perpendicular to the web forming hole, and an upper surface flange communication hole 29 formed at the other end of the web forming hole 28. Here, the web forming hole 28 is formed so as to be parallel to the side wall 31 of the moving die 11, and the web forming hole 2 is formed.
8 is formed to have the same length as the shortest length h2 of the web 4 shown in FIGS.
Is formed to have a size larger than the above-described upper surface flange forming hole 15.

Similarly to the fixed die 10, the movable die 11 is formed in a substantially rectangular plate shape using hot tool steel or the like. Then, as shown in FIG. 8, a head 25 inserted into the guide hole 22 and a drive means (not shown) such as a hydraulic cylinder for sliding the head 25 in the guide hole 22 are connected. It has a clamp portion 26.

The movable die 11 is housed in the guide hole 22 of the fixed die 10 such that the lower surface flange forming hole 27 is located on the lower surface flange communication hole 17 side of the fixed die 10. Then, the movable die 11 is slid along the guide wall 23 in the guide hole 22 of the fixed die 10 so that the web forming holes 16 and 28 communicate with each other, and is arranged at a predetermined position.

The extrusion die composed of the stationary die 10 and the moving die 11 arranged as described above is placed on the container 2
When the extruded material is introduced from 1, the extruded material is extruded through an overlapping portion of the extruded hole 14 of the fixed die 10 and the extruded hole 30 of the movable die 11. At this time, by sliding the moving die 11, a both-end supporting beam having a continuous cross-sectional shape can be manufactured as shown in FIGS.

Next, a method of extruding the both-end supporting beam 1 of the present invention with a variable cross-section using the extrusion die having the above-described configuration will be specifically described with reference to FIGS.

The hatched portions shown in FIGS. 9 and 10 correspond to the extrusion hole 14 of the fixed die 10 and the moving die 1.
The shape of one extrusion hole 30 is shown. Also,
FIGS. 11 to 13 show the mutually overlapping state of the extrusion hole 14 of the fixed die 10 and the extrusion hole 30 of the moving die 11. The portion where each hatch overlaps shows the cross-sectional shape of the both-ends support beam formed by extrusion.

First, as a first step, the process of forming the region a between the points O and P shown in FIG. 1 will be described.
As shown in FIG. 11, the moving dice 11 and the fixed dice 10
Means that the upper surface flange communication hole 29 of the movable die 11 overlaps the upper surface flange forming hole 15 of the fixed die 10, and
The lower surface flange forming hole 27 of the movable die 11 is arranged so as to overlap the lower surface flange communication hole 17 of the fixed die 10. Further, at this time, the length from the upper surface side of the upper surface flange forming hole 15 to the lower surface side of the lower surface flange forming hole 27 is H1.
The movable die 11 is slid so that In this state, the extruded material is introduced into the extrusion die in which the movable die 11 and the fixed die 10 are arranged, so that the molded material having a shape as shown in FIG. Only formed. The length of the web of the formed material having a substantially T-shaped cross section at this time is as follows:
h1.

Next, as a second step, the process of forming the region b between the points P and Q shown in FIG. 1 will be described. As shown in FIG. 12, the movable die 11 is moved so that the upper flange communication hole 29 of the movable die 11 is separated from the lower flange communication hole 17 of the fixed die 10, and the lower flange is formed from the upper surface of the upper flange forming hole 15. Hole 2
7 from H1 shown in FIG. 11 to FIG.
And continuously moved while extruding until H2 shown in FIG. By setting the moving speed of the moving die 11 and the extrusion speed of the extruded material to predetermined speeds at this time, a predetermined length from point P to point Q is extruded as shown in FIG. In the meantime, the length from the upper flange 2 to the lower flange 3 continuously changes from H1 to H2. At this time, the lower surface flange communication hole 2 of the fixed die 10
The side wall surface 41 on the side of the side wall 9 where the web forming hole 16 is provided and the side wall surface 42 of the lower surface flange forming hole 27 of the movable die 11 on the side of the web forming hole 28 are aligned. I have. Further, the length of the web of the formed material having a substantially T-shaped cross-section formed at this time corresponds to the continuous change of the length from the upper flange 2 to the lower flange 3 from H1 to H2. , H1 to h2 continuously.

Next, as a third step, the process of forming the region c between the point Q and the point R shown in FIG. 1 will be described. As shown in FIG. 13, the moving die 11 is further moved in the same direction at the same speed as the above-described second stage moving speed. Due to the movement of the moving die 11, the position of the half of the length t 1 of the lower surface flange forming hole 27 of the moving die 11 is shifted to the position of the lower surface flange communication hole 29 of the fixed die 10 where the web forming hole 16 is provided. Side wall surface 41
To the position where it intersects. In the portion that is extruded in the molding process, that is, in the overlapping portion of the movable die 11 and the fixed die 10, as the movable die 11 moves, the upper flange 2 side of the lower flange forming hole 27 decreases. Therefore, in the molded material extruded in the third stage molding process, the dimension of the upper surface flange 2 and the length of the web 4 do not change, and the thickness of the lower surface flange 3 changes from t1 to t2. As a result, the web length h2 does not change between the point Q and the point R, but as the thickness of the lower surface flange 3 decreases continuously from t1 to t2, the cross-sectional length of the molding material also decreases. H2 continuously changes from H2 to H3.

Next, as a fourth step, a process of forming the region d between the points R and R 'shown in FIG. 1 will be described. After reaching the point R by performing the third-stage molding process described above, the movement of the movable die 11 is stopped. And FIG.
In this state, the extrusion is continued, and the extrusion is continued for a predetermined length up to the point R ′, whereby a molded material having the cross-sectional shape of FIG. 13 is formed.

Further, as shown in FIG. 1, since the both-end supporting beam 1 is symmetrical about the point S, the above-described extrusion is performed by performing the extrusion in the reverse procedure. The support beam 1 at both ends shown in FIG.

That is, as a fifth step, the formation of the region c ′ between the points R ′ and Q ′ shown in FIG. 1 is performed by performing the procedure reverse to the above-described third step. That is, after reaching the point R ′, the moving die 11 and the fixed die 10 are moved at a predetermined speed so that the positional relationship between the state shown in FIG. 13 and the state shown in FIG. Forms a molding material changed from t2 to t1.

Next, as a sixth step, Q ′ shown in FIG.
The formation of the region b ′ between the point and the point P ′ is performed by performing the procedure in the reverse order of the above-described second step. That is, after reaching the point Q ', the moving die 11 and the fixed die 1
0 is moved at a predetermined speed from the state shown in FIG. 12 to the state shown in FIG.
While the predetermined length up to the point is extruded, a molding material in which the length from the upper flange 2 to the lower flange 3 continuously changes from H2 to H1 is formed.

Next, as a seventh step, P ′ shown in FIG.
The formation of the region a ′ between the point and the point O ′ is performed by performing the procedure in the reverse order of the above-described first step. That is, after reaching the point P ', the movement of the moving die 11 is stopped. Then, in the state shown in FIG. 11, the extrusion is continued, and the extrusion is continued for a predetermined length up to the point O ′, thereby forming a molded material having a sectional shape of the region a ′.

1 to 4 by the above respective molding steps.
Can be formed. The guide hole 22 provided in the fixed die 10 is provided with the movable die 11.
Is stably slidably held, so that the working accuracy of the formed both-end supporting beam can be improved.

Therefore, since the both-end supporting beam 1 formed by the variable cross-section extrusion method is continuously formed without any seam, it has a higher corrosion resistance than the conventional two-side supporting beam manufactured by welding, bolting or cutting. As a result, the manufacturing process can be simplified and the manufacturing cost can be reduced. Further, the shape of the die can be changed, the moving speed and the extrusion speed of the die can be adjusted, and the cross-sectional shape can be changed by further using the third die.

Further, the both-end supporting beam 1 is not limited to being manufactured by the above-described variable cross-section extrusion method, but is preferably formed of a seamless material. Therefore, the beam at both ends can be formed by cutting or pressing, but the shape is limited, and it is difficult to easily form the beam as shown in FIGS. However, in the case of forming by cutting or pressing, although the manufacturing cost is slightly inferior, deformation and corrosion are less likely to occur than in welding or bolting.

Although it is preferable to use aluminum or an aluminum alloy as the extruded material, other lightweight materials may be used. Even when such a lightweight member is used, the both-ends supporting beam of the present invention has its cross-sectional shape changed from both end portions to the central portion so as to have a smaller cross-sectional modulus so as to have substantially equal strength. Therefore, the strength does not decrease as compared with a beam using a conventionally used steel material. Therefore, when applied to both ends supporting beams for transportation equipment, for example, a center beam, it is possible to achieve a reduction in weight, and to prevent a reduction in the loading capacity due to deflection,
The weight of the transportation equipment as a whole can be reduced.

As the cross-sectional shape of the both-ends supporting beam 1, the cross-sectional shape of the above-mentioned substantially T-shaped cross-section can be preferably used, but the cross-sectional shape of the cross-section of the both-ends supporting beam is away from the neutral axis. It is not particularly limited as long as it is performed. For example, it may be one having an I-shaped or H-shaped cross-sectional shape, or a cross-sectional shape changed into a different shape along the longitudinal direction of the beam by a variable cross-sectional extrusion method, for example, from a substantially T-shaped to a substantially I-shaped. It may have a cross-sectional shape that continuously changes into a letter shape. Since the cross-sectional shape can be increased by forming the cross-sectional shape as far away from the neutral axis as possible, a material having a small Young's modulus such as aluminum or an alloy thereof is used. Also, the beam can be given sufficient strength without increasing the outer dimensions of the cross section. Also, the weight of the beam can be reduced.

The beam 1 supported at both ends of the present invention is connected to a packing box 152 of a wing body type truck 151 as shown in FIG.
When the center beam 154 is used as the center beam 154, the volume in the packing box 152 is not reduced even if the center beam 154 is bent, so that the loading amount is not reduced. In addition, since the cross-sectional shape is changed continuously or stepwise from both ends to the central portion so as to reduce the cross-sectional modulus, the material of the central portion can be reduced, and the weight of the center beam 154 can be reduced. Can be. In addition, members other than the center beam 154 can be preferably used as other components of the transportation equipment for which it is desired to achieve an adverse effect due to deflection and a reduction in weight. In addition, the both-ends-supported beam of the present invention can be preferably used for components other than transportation equipment, for example, building materials for construction, and does not cause any problem even if deflection occurs.

Further, in the present invention, the both-end supporting beams having the shapes shown in FIGS. 1 to 4 have been specifically described, but the overall shape or the cross-sectional shape of the beams is not limited to the above. For example, a continuously changing portion as shown in a region b of FIG. 1 may extend over the entirety, or a portion having the same shape and a predetermined length, such as a region a and a region d. May be provided in a step-like shape in which a number of are provided via a continuously changing portion such as a region b.

[0057]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The beam supported at both ends of the present invention will be described below with reference to specific examples.

As the center beam 154 used for the packing box 152 of the wing body type truck 151 as shown in FIG. 15, a center beam 154 having the following size was formed by a variable cross-section extrusion method.

As the dimensions of each part in FIGS. 1 to 4, W = 1
25 mm, w = 75 mm, L = 25 mm, t1 = 10 m
m, t2 = 5 mm, H1 = 100 mm, H2 = 63 m
m, H3 = 58 mm, O point to P point = 800 mm, P point
Q point = 1000 mm, Q point to R point = 50 mm, R point
R ′ point = 9600 mm, R ′ point to Q ′ point = 50 mm,
Q 'point to P' point = 1000 mm, P'point to O 'point = 80
A center beam 154 containing each dimension element of 0 mm was manufactured by a variable cross-section extrusion method.

This center beam 154 is
H1 to H3 so as not to interfere with the cargo
Since there was a maximum height limit of 100 mm in the above, a substantially T-shaped cross-sectional shape was adopted so as to have a large cross-sectional modulus in that range.

Each dimension was adjusted by controlling a variable cross-section extrusion die consisting of a fixed die and a moving die. As an extruded material, a 6N01 aluminum alloy was used.

In the obtained center beam 154, a deflection of about 28 mm occurred at the point S where the deflection was the largest, but the lower side of the middle portion was reduced so that the difference between H1 and H3 was 42 mm. Because of the bent shape, the bent portion did not exceed the extension of the support at both ends. Further, the length of one side conventionally used is 100.
center beam 15 of square steel pipe with square cross section
It was possible to reduce the weight by about 45 kg compared to 4.

[0063]

As described above, according to the beam supported at both ends of the present invention, the height of the beam changes from the both ends to the center of the beam so that the section modulus becomes smaller. Each part is generally of equal strength. As a result, the bending moment of each part of the beam is reduced, and the deflection length of the beam can be reduced. In the present invention, without changing the upper side of the both-end supporting beam, the lower side thereof is reduced by a length equal to or more than the bending length of each part, for example, when used as a both-end supporting beam for transportation equipment In addition, the deflection generated in each part of the beam does not come into contact with the cargo, so that there is no problem that the load is reduced. In addition, since it has the above-mentioned cross-sectional shape which is substantially equal in strength, the strength of the beam is not reduced. Furthermore, since the section modulus is changed so as to decrease from both end portions to the center portion, the weight of the beam itself can be reduced, and the weight of the middle portion where bending is most likely to occur can be reduced.
The deflection length can be reduced.

Further, the cross section of each section from the both ends of the beam toward the center thereof is formed into a substantially T-shaped cross section disposed at a position away from the neutral axis of the cross section of the beam supported at both ends, whereby the both ends are formed. Even if the beam is supported at both ends and has a cross-sectional shape changed so that the cross-sectional modulus decreases from the center to the center, the cross-sectional modulus is adjusted so that the mechanical strength of the beam can be maintained. As a result, the strength of the beam can be maintained even if the lower side of the support beam at both ends is reduced by a length equal to or greater than the bending length of each part. Further, since the lower side of the obtained both-end supporting beam is reduced by a length equal to or longer than the bending length, there is no adverse effect due to the bending.

In particular, when the cross-sectional shape of the beam supported at both ends is formed by a variable cross-section extrusion method performed by controlling a plurality of dies, the cross-sectional shape can be easily changed. The support beams at both ends can be integrally formed in one step. It is also preferable in terms of simplification of the manufacturing process and reduction of the manufacturing cost as compared with a conventional both-end supporting beam formed by welding, bolting, cutting, or the like.

Further, since the both-end supporting beam is made of aluminum or aluminum alloy which is a lightweight material, the weight can be reduced as compared with the conventionally used both-end supporting beam using a steel material. Also, since the beam has the above-described cross-sectional shape such that the beam has substantially equal strength,
It does not reduce the mechanical strength of the beam. Therefore, for example, when used as a support beam at both ends for transportation equipment, the length of flexure generated at the middle portion of the beam can be reduced, and the beam does not come into contact with the cargo, and the load capacity is reduced. It is possible to reduce the weight of the transportation equipment without causing any trouble.

If the beam supported at both ends of the present invention is used for the center beam of the packing box of a wing body type truck, the volume in the packing box will not be reduced even if the center beam is bent. As a result, the load of the wing body type truck is not reduced. In addition, since the cross-sectional shape has a substantially equal strength, it is possible to reduce the constituent material, particularly in the central portion, and to reduce the weight of the center beam.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a beam supported at both ends according to the present invention.

FIG. 2 is a sectional view taken along line AA of the both-end supporting beam shown in FIG.

FIG. 3 is a sectional view of the both-end supporting beam shown in FIG.

FIG. 4 is a cross-sectional view of the beam at both ends taken along line CC of FIG. 1;

FIG. 5 is a front view showing a bent state of the both-end supporting beam shown in FIG. 1;

FIG. 6 is a plan view showing an example of a first die used for variable-section extrusion.

FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6;

FIG. 8 is a plan view showing an example of a second die used for variable section extrusion.

FIG. 9 is a plan view showing a shape of an extrusion hole of a first die.

FIG. 10 is a plan view showing a shape of an extrusion hole of a second die.

11 is a plan view showing the positional relationship between the extrusion holes of the first die and the extrusion holes of the second die when extruding with the cross-sectional shape shown in FIG. 2;

FIG. 12 is a plan view showing a positional relationship between an extrusion hole of a first die and an extrusion hole of a second die when extruding with the cross-sectional shape shown in FIG. 3;

FIG. 13 is a plan view showing a positional relationship between an extrusion hole of a first die and an extrusion hole of a second die when extruding with the cross-sectional shape shown in FIG.

FIG. 14 shows an example of a conventional center beam using a 100 mm square steel pipe.

FIG. 15 is a schematic view showing an example of an embodiment in which the beam supported at both ends of the present invention is used as a center beam of a packing box of a wing body type truck.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Both ends support beam 2 Upper surface flange 2a Hanging part 3 Lower surface flange 4 Web 5 Lower side of both ends support beam 10 Fixed die 11 Moving die

Claims (6)

[Claims] An end supporting beam having a height changed so that the section modulus decreases from both end portions to a central portion, wherein a lower side of the both end supporting beam is longer than a bending length of each portion of the both end supporting beam. A beam supported at both ends, reduced in length. 2. The method according to claim 1, wherein the both-end supporting beam has an upper surface flange,
It has a substantially T-shaped cross-sectional shape consisting of a lower surface flange and a web connecting the upper surface flange and the lower surface flange, and has both ends having a predetermined cross-sectional shape having a constant cross-sectional shape from both ends to the center. And the lower side of the support beam at both ends,
A variable cross-section where the web continuously changes so as to be reduced by a length equal to or greater than the bending length of each end supporting beam, a section where the thickness of the lower surface flange changes continuously and thinly, and a section modulus 2. An intermediate portion having a predetermined length and a constant cross section having a small cross section.
The beams supported at both ends. 3. The both-end supporting beam according to claim 1, wherein the both-end supporting beam is formed of a seamless material. 4. The both-end supporting beam according to claim 1, wherein the both-end supporting beam is formed by a variable cross-section extrusion method. 5. The both-end supporting beam according to claim 1, wherein said both-end supporting beam is formed of aluminum or an aluminum alloy. 6. The support beam according to claim 1, wherein the beam is a center beam used for a packing box of a wing body type truck.