JPH042328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for bending a honeycomb core.
That is, the present invention relates to a method of bending a flat honeycomb core made of expanded cells having a substantially regular hexagonal cross section in a ribbon direction perpendicular to the expanded direction.

The three-dimensional honeycomb core obtained in this way, that is, the three-dimensional honeycomb core that is bent in the ribbon direction and has a bent part along the stretching direction, is widely used for various three-dimensional structures. ing. In other words, the three-dimensional honeycomb core is used as a core material for three-dimensional structures that are lightweight and have excellent strength, such as three-dimensional building materials, construction materials, transportation equipment, furniture fittings, kitchen utensils, etc., as well as aircraft and It is widely used for curved structural members such as boats and yachts, master models and replica models with standard curved surfaces used in the manufacturing process of various sheet metal parts, etc.

"Technical Background" Honeycomb cores generally have a high strength-to-weight ratio, that is, they are lightweight and have excellent strength, so they are widely used as core materials for various flat structures. However, it has generally not been easy to form a three-dimensional honeycomb core that is bent and wrinkled by post-processing such a flat honeycomb core.

Now, among the flat honeycomb cores, in particular, the flat honeycomb core, which is formed by expanding and is made up of a flat aggregate of cells in the form of short cylinders and hollow columns with an approximately regular hexagonal cross section, has an extremely high strength to weight ratio. Because it is easy to form, it is commonly used, and is widely used as core materials for various flat structures. FIG. 4 is a perspective view showing a state in which such a flat honeycomb core is expanded and formed. Using the honeycomb core 1, it is bent in the ribbon direction L perpendicular to the expansion direction W. Conventionally, it has been considered very difficult to form a bent portion along the stretching direction W, that is, to form a three-dimensional honeycomb core curved in the ribbon direction L in this way.

"Prior Art" That is, in a flat honeycomb core 1 in which the cells 1a are expanded and formed to have a substantially regular hexagonal cross section, the cell walls 1b along the ribbon direction L are made of two layers of material bonded together, as is well known. Since the cell wall 1b is extremely rigid compared to other cell walls 1b made of a single sheet of material, it has been considered extremely difficult to form a bent portion bent in the ribbon direction L. (On the other hand, bending in the stretching direction W was considered relatively easy since it was only necessary to bend each cell wall 1b.) In addition to the rigidity of the core material, bending Since the amount of displacement of the cell wall 1b in the direction perpendicular to the axis is large, and the displacement of the cell wall 1b works in opposite directions above and below the core, the stretching direction W is the ribbon direction L to be bent, for example, the opposite direction from the top and bottom. Because it had the property of warping in the opposite direction, for example upwards, and forming a saddle shape,
It was considered impossible to form a highly precise three-dimensional honeycomb core. Note that if you apply excessive force to bend the cell wall 1b as specified, the cell wall 1b may break or the bonded parts of the cell wall 1b may peel off, causing concerns about rigidity and strength. It was not possible to form a three-dimensional honeycomb core. Furthermore, since the bending radius in the ribbon direction L must be increased during formation, it has been considered impossible to form a three-dimensional honeycomb core with a small bending radius.

As described above, it has generally been considered difficult to obtain such a three-dimensional honeycomb core, but the following first, second, and third techniques have been developed in the past. First, the first conventional example is as follows. That is, it is widely practiced to form a three-dimensional structure by using the flat honeycomb core 1 as a core material instead of the three-dimensional honeycomb core, and in this conventional example, the flat honeycomb core 1 is used as the core material. A three-dimensional structure was formed by connecting the ends of a plurality of flat honeycomb panels together via a connecting member separately provided with a bending portion.

The second conventional example is as follows. That is, as a method for forming a three-dimensional honeycomb core as a core material of a three-dimensional structure, a method has been proposed in which an unexpanded portion is formed in advance during expansion, and this is used to perform bending. In other words, a three-dimensional honeycomb core was formed as shown in FIGS. 1a and 1b, in which the cells 1a were stretched and had a substantially regular hexagonal cross section, and had bent portions bent in the stretching direction W. When this three-dimensional honeycomb core A is stretched, first, the portion where the bent portion B is to be formed is held in an unstretched state within an appropriate range by fixing it with, for example, a clip C, and then stretching it. , an unexpanded part A' is formed in advance in what will become the three-dimensional honeycomb core A, and this unexpanded part
A method was provided in which A' was applied to mold D to form bent portion B.

Furthermore, the third conventional example is as follows.
That is, as shown in Japanese Patent Publication No. 47-41851, each cell wall 1b of a flat honeycomb core 1 whose cells 1a have a substantially regular hexagonal cross section (see FIG. 4)
Regarding this, a technique has also been proposed that enables bending by making linear, V-shaped, Y-shaped, etc. cuts deep enough to avoid completely cutting the cell wall 1b. .

"Problems to be Solved by the Invention" By the way, the following problems have been pointed out in such conventional examples.

First, the above-mentioned first conventional example, that is, a conventional example in which the flat honeycomb core 1 is used as a core material and is connected via a connecting member is as follows. That is, a three-dimensional structure formed by such a bonding structure has a complicated structure and is expensive, and also has the disadvantage that the characteristics of the honeycomb core 1, which is lightweight and excellent in strength, are impaired. . Next, the above-mentioned second conventional example, that is, the conventional example in which the unexpanded portion A' is formed in advance as shown in FIG. 1, is as follows. That is, in this method, for the flat honeycomb core 1 in which the cells 1a are stretched and have a substantially regular hexagonal cross section, a three-dimensional honeycomb core 1 having a bent portion B bent in the stretching direction W is generally used for the same reason as described above. It is certainly possible to form a shaped honeycomb core. However, it is impossible to form the bent part B bent in the ribbon direction L perpendicular to this due to the rigidity of the double bonded cell wall 1b. It has been pointed out that the stretching process of the three-dimensional honeycomb core A is troublesome, making the three-dimensional honeycomb core A expensive, and that accurate positioning of the bent portion B is difficult.

Furthermore, the third conventional example mentioned above, that is, the
As shown in Publication No. 41851, a conventional example in which a notch is cut is as follows. In other words, in this conventional example, as shown in the figures in the publication, by using notches, bends with a gentle curve and a large bending radius can be formed without considering the directionality, but in the ribbon direction. It is difficult to obtain a three-dimensional honeycomb core bent with a large steep curve such as perpendicular to L, that is, with a small bending radius. In other words, the flat honeycomb core 1 is formed by expansion and the cells 1a have a substantially regular hexagonal cross section.
Regarding, if a deep cut is made in the cell wall 1b along the ribbon direction L where the material is double bonded and has strong rigidity, the rigidity of that part will be extremely reduced and the strength to weight ratio will be large. The characteristic of the honeycomb core 1 that is In other words, the core density in that part decreases due to the notch, and a portion of the cell wall 1b is cut or notched, so a significant decrease in the strength of the cell wall 1b is unavoidable. Even if it were assumed that the ribbon could be bent with a small bending radius such as perpendicular to the ribbon direction L, there would be great concerns regarding the strength.

"Means for Solving the Problems" The present invention was made in view of the above-mentioned circumstances, and consists of the following technical means. In other words, in this method, a flat honeycomb core consisting of a flat aggregate of cells in the form of short cylinders and hollow columns that are formed by expansion and whose planar shape is approximately regular hexagonal in cross section is bent in a ribbon direction perpendicular to the direction of expansion. Regarding. First, a pressing force is applied to the cell wall along the expansion direction using a mold material to cause the cell wall to collapse and buckle, thereby forming a buckled recess along the expansion direction. Then, bending is performed along the buckling recess so that the buckling recess is on the inside, thereby forming a bent part bent in the ribbon direction and extending in the stretching direction.

"Function" Since the method for bending a honeycomb core according to the present invention includes such means, it works as follows.
That is, using a flat honeycomb core made of expanded cells with a substantially regular hexagonal cross section, first the cell walls are buckled along the expansion direction, and then the cells are buckled along the buckling recesses. By bending inward, a predetermined three-dimensional honeycomb core bent in the ribbon direction can be obtained.

Firstly, a honeycomb core with a predetermined three-dimensional shape can be easily obtained through simple work, secondly, the characteristics of being lightweight and excellent in strength are not impaired, and thirdly, the bending radius can be very small. It can be formed in the ribbon direction and fourthly, it can be formed with high precision.

"Example" The present invention will be described in detail below based on the example shown in the drawings.

In FIGS. 2 and 3, reference numeral 1 denotes a flat honeycomb core 1 that is formed by expanding, and this honeycomb core 1 is produced by a known manufacturing method, that is, by stacking a large number of thin plate materials on the opposing surfaces. Formed by gluing and expanding the required parts,
It consists of a general flat plate. The honeycomb core 1 is expanded and formed as a planar assembly of cells 1a in the shape of short cylinders and hollow columns with a planar shape of a substantially regular hexagonal cross section. 3 is a straight bent part forming position line set to form a predetermined bent part 2 for such a honeycomb core 1, and this bent part forming position line 3 is set as shown in FIG. In order to form a bent portion 2 bent in the ribbon direction L on the honeycomb core 1, it is set along the stretching direction W orthogonal to the ribbon direction L.

Then, as shown in FIG. 3, for each cell 1a, 1a... located along this bending part forming position line 3, for example, the tip is A pressing force greater than the compressive strength of the honeycomb core 1 is applied in the cell axis direction by the flat and thin shape member 4. As a result, a part of each cell wall 1b, 1b... is buckled so as to be crushed simultaneously, and a buckled recess having a predetermined width and depth is formed along the bending part forming position line 3 and the extension direction W. form 5.

Next, a bending die 6 is applied along the buckling recesses 5 formed in each of the cell walls 1b, 1b, . . . to bend the honeycomb core 1 in the ribbon direction L so that the buckling recesses 5 are on the inside. Then, due to the formation of the buckling recesses 5, the amount of displacement of the cell walls 1b becomes small, and stress concentration occurs to locally cause buckling in the buckling recesses 5, so that the honeycomb core 1 easily moves along the buckling recess 5 in the ribbon direction L
It is bent to In particular, the cell wall 1b along the ribbon direction L has two layers of material bonded together, and has extremely high rigidity compared to the other cell wall 1b made of a single material. Since it is bent, it can be bent easily and accurately without any problems.

Therefore, the position of the predetermined bending part forming position line 3 set along the stretching direction W can be precisely positioned, for example, as shown in the figure, the bending radius in the ribbon direction L is approximately perpendicular, and the bending radius in the ribbon direction L is very small, and the core density is high bending part 2
is formed along the stretching direction W by being bent in the ribbon direction L. Note that the cross-sectional shape of the bending die 6 is set in consideration of the spring back according to the material, thickness, cell size of the honeycomb core 1, the angle of the bent portion 2 to be formed, and the like. Further, the width, depth, etc. of the buckling recess 5 are also set depending on the material of the honeycomb core 1, the angle of the bent portion 2 to be formed, etc. A predetermined three-dimensional honeycomb core can be easily formed by the above-described method, and the formed three-dimensional honeycomb core has a much higher core density in the bent portion 2 than that in the flat plate portion. has strength greater than that of the flat plate part.

"Effects of the Invention" As explained above, the method for bending a honeycomb core according to the present invention is characterized by forming predetermined buckling recesses along the stretching direction.
Demonstrates the third and fourth effects.

First, it is easy to operate and is cost-effective.
A three-dimensional honeycomb core is obtained. In other words, unlike conventional examples of this type, the flat honeycomb cores are not connected using a connecting member or each unexpanded portion is formed using clips, and the process of buckling and bending can be easily performed. Due to the work and structure,
It is low cost and provides a predetermined three-dimensional honeycomb core.

Second, the characteristics of the honeycomb core, which is lightweight and excellent in strength, are not impaired. That is, first of all, the core density at the bent part is high due to the buckling recess, and unlike conventional examples of this type, there is no cut in the bent part or a connecting structure is required, so the strength to weight ratio is high, which means it is lightweight and strong. The excellent characteristics of the honeycomb core in which the cells have a substantially regular hexagonal cross section are not impaired in any way, and a three-dimensional honeycomb core with excellent strength can be obtained.

Thirdly, a bent portion with a very small bending radius can be easily formed in the ribbon direction. In other words, a flat honeycomb core is used which is formed by expanding and the cells are approximately regular hexagonal in cross section. Despite the rigidity of the cell walls, due to buckling and bending processing, the cells form a large sharp curve in the ribbon direction and become clogged. , a three-dimensional honeycomb core bent with a small bending radius is obtained. In other words, unlike conventional examples of this type, there is no limitation to those that are bent in the stretching direction or those that have a gentle curve and a large bending radius.

Fourth, the bends are accurately positioned along the direction of expansion. In other words, despite the rigidity of the cell walls, by buckling the cell walls along the stretching direction, a highly accurate three-dimensional honeycomb core is formed that does not warp or form a saddle shape, but is curved in the ribbon direction. be done. In addition, since there is no need to apply excessive force to bend the honeycomb core, breakage of cell walls and peeling of bonded areas are prevented, and from this aspect as well, a three-dimensional honeycomb core with high precision can be obtained.

As described above, the present invention has remarkable and great effects, such as all the problems that existed in this type of conventional example being wiped out in one fell swoop.

[Brief explanation of drawings]

FIGS. 1A and 1B are end views showing the main steps of a conventional honeycomb core bending method. 2 and 3 show an embodiment of the present invention, and FIG. 2 is a plan view of a flat honeycomb core showing set position lines for forming bent portions, etc.; , b, c, and d are end views sequentially showing the bending stroke. FIG. 4 is a perspective view showing a state in which a flat honeycomb core is expanded and formed. In the figure, 1 is a honeycomb core, 1a is a cell, 1b is a cell wall, 2 is a bent part, 3 is a position line for forming the bent part, 4
5 is the buckling recess, 6 is the bending die, L is the ribbon direction, and W is the stretching direction.

Claims (1)

[Scope of Claims] 1. A flat honeycomb core 1 consisting of a flat aggregate of cells 1a in the form of short cylinders and hollow columns that are formed by being stretched and whose planar shape has a substantially regular hexagonal cross section is formed into a ribbon perpendicular to the stretching direction W. This is a method of bending in the direction L. First, a pressing force is applied to the cell wall 1b using the shape material 4 along the stretching direction W, and the buckling recess 5 along the stretching direction W is made to collapse and buckle. and then bending along the buckling recess 5 so that the buckling recess 5 is on the inside, thereby forming a bent part 2 bent in the ribbon direction L and along the stretching direction W; A honeycomb core bending method featuring: