JP4742375B2 - Bell-shaped hollow metal sphere for shock absorption and structural material for shock absorption - Google Patents

Description

The present invention relates to a bell-shaped hollow metal sphere for shock absorption and a structure for shock absorption.
As a measure against global warming, the weight of automobiles has been reduced for the purpose of further improving fuel efficiency. On the other hand, in order to satisfy automobile safety standards, high rigidity is also required. However, high rigidity is usually accompanied by an increase in weight. In order to satisfy these conflicting requirements, it has been studied to fill a pillar or crush box with an ultralight hollow metal sphere having a light weight and high energy absorption characteristics and use it as an energy absorbing material. The present invention relates to a shock-absorbing bell-shaped hollow metal sphere suitable for such applications, a manufacturing method thereof, and a shock-absorbing structural material.

  The present inventor has already provided a shock-absorbing structural material in which a large number of hollow metal spheres are continuously bonded by utilizing the high impact energy absorption capability of the hollow metal spheres (WO 2005-084854). This shock-absorbing structural material is very effective in reducing the weight while maintaining the rigidity of the automobile, but in order to obtain this shock-absorbing structural material, a hollow metal sphere itself must be obtained.

As a manufacturing method of the hollow metal sphere described above, there are conventional techniques of Patent Document 1 and Patent Document 2.
The prior art of Patent Document 1 is made of a metal such as nickel, iron, aluminum, or copper, or an alloy thereof, and has a hollow portion that is cut off from the outside, and has a spherical shape that does not have a joint or an opening, or a similar shape thereto. A thin-walled hollow body comprising a step of granulating a molten metal or alloy, a liquid capable of vaporizing the granulated metal or alloy at a temperature lower than their melting point, and a gas by chemical reaction. And a step of contacting the liquid or solid that can be generated, and the gas generated at the time of contact is trapped inside the granulated metal or alloy melt and has a hollow portion that is blocked from the outside. The hollow metal sphere is formed.

  In the prior art of Patent Document 2, a metal melt is formed by colliding a metal melt flow with a rotating body placed in a fluid or part of a liquid and dispersing it to form a metal melt in the liquid. And a liquid are brought into contact with each other, and a gas generated at that time is placed in a metal melt to form a hollow portion.

  However, the conventional examples of Patent Documents 1 and 2 have problems that the material cost is high and the number of processes is large, so that the manufacturing cost is high, and the dimensional accuracy of the hollow metal sphere is low during molding.

By the way, any of the above prior arts has attempted to obtain a hollow metal sphere having no seam or opening and having a completely sealed surface.
However, according to the inventor's research, it has been found that the hollow metal sphere does not necessarily need to be completely sealed. For example, even if the hollow metal sphere has a small opening, such a hollow metal sphere with an opening (hereinafter referred to as a hollow metal sphere having such a shape in this specification) It has been found that when a large number of is used, the shock absorbing ability is equal to or higher than that when a completely sealed hollow metal sphere is used. The reason for this is that if there are openings, the hollow metal spheres exhibit direction dependency of the compression resistance, but when many hollow metal spheres are filled into the sealed space, the orientation and position of the openings are random. This is because, as a whole, the compressive resistance does not depend on the direction and the deformation until densification is large due to the opening.

Japanese Patent Publication No.52-15057 JP-B 53-2420

  In view of the above circumstances, an object of the present invention is to provide a bell-shaped hollow metal sphere having a high impact absorption capability and capable of forming a shock-absorbing structural material in a light weight. Another object of the present invention is to provide a lightweight shock absorbing structural material having a high shock absorbing capacity.

Bell-shaped hollow metal spheres for shock absorption of the first invention, the pressurizing a metal ball for impact absorption going collapsed by gradually pressure, the hollow by bending a metal sheet obtained by forming a spherical partition wall It is a sphere, and an opening is formed in the partition wall, and the opening consists of two small holes and a slit connecting them .
The shock absorbing structural material of the second invention is characterized in that the hollow structure is filled with the bell-shaped hollow metal sphere of claim 1.

The bell-shaped hollow metal sphere of the first invention has the following effects.
a) Although there is an aperture, the basic shape is a sphere and it is hollow, so it is lightweight. In addition, since the shape is a sphere, the compression resistance is high, and since it is gradually crushed by pressurization, the shock absorbing ability is very high.
b) Since the bell-shaped hollow metal sphere has two holes and an opening made up of slits connecting them, there is a direction dependency of the ease of being crushed by pressure, but there are many bell-shaped hollow metal spheres in the sealed space. When the hole is filled, the direction of the opening is random, so that the direction dependency of the ease of crushing does not appear as a whole, and the same shock absorbing ability can be exhibited in any direction.
According to the second invention, the internal structure of the shock absorbing structure is filled with a large number of bell-shaped hollow metal spheres. As it is crushed one by one, the shock-absorbing structural material will be deformed over time and will not collapse at once. Since the energy absorbing characteristics are exhibited in this way, the thickness of the shock absorbing structural material can be reduced, and a shock absorbing structural material that is lightweight and has high shock absorbing capability can be provided.

Next, an embodiment of the present invention will be described with reference to the drawings.
First, an embodiment of the bell-shaped hollow metal sphere of the present invention will be described. External view of bell-shaped hollow metal ball 1 of the (A) FIG Example 1 FIG. 1, (B) drawing (A) showing the cross section B-B. External view of bell-shaped hollow metal balls 2 (A) figure 2 Example 2, (B) Fig. Is a cross section B-B of (A) and FIG. Incidentally, (A) figure 3 is an external view of a bell-shaped hollow metal ball 3 as a reference example, (B) drawing a B-B section of Figure (A).

Bell-shaped hollow metal spheres 1 (A), the first embodiment shown in (B) of FIG. 1 is a hole portion 1b is formed in a spherical shape of the partition wall 1a. The opening 1b has a shape in which two small holes h are connected by thin slits s. The small hole h is substantially circular. As will be described later, the small hole h can be made close to a circle by making the initial blank shape appropriate.
Bell-shaped hollow metal balls 2 (A), in the second embodiment shown in FIG. 2 (B) is for opening 2b is formed in a spherical shape of the partition wall 2a. The opening 2b has a shape in which two small holes h are connected by thin slits s, but the small holes h are not circular but are thin rhomboid holes.
The opening portion of the present invention may have a shape similar to those other than those exemplified in the first and second embodiments.
Note that the bell-shaped hollow metal sphere 3 as a reference example shown in FIGS. 3A and 3B has a spherical partition wall 3a with an opening 3b. The opening 3b is composed of two small holes h, and the two small holes are circular in a centrally symmetric position .

Next, a method for using the bell-shaped hollow metal sphere of the present invention will be described.
FIG. 4 shows the hollow shock absorbing structural material 5 filled with the bell-shaped hollow metal sphere of Example 1 . As shown in the figure , the opening portions 1b of many bell-shaped hollow metal spheres 1 are oriented in random directions. These bell-shaped hollow metal spheres 1 may be bonded to each other by an adhesive material or diffusion bonding, or may be used separately without being bonded.

  The shock-absorbing structural material 5 is, for example, a hollow structure that is used for a frame, a bumper of an automobile, a beam of a building, a pillar, etc. However, there is no particular limitation as long as it has a hollow space inside.

  As described above, the inside of the shock absorbing structural member 5 is filled with a large number of bell-shaped hollow metal spheres 1, so that when an external impact load is applied, the inner bell-shaped hollow metal spheres 1 are impacted. Due to the absorption load, the deformation of the shock absorbing structural material 5 hardly occurs until a certain load is applied. And if an impact load becomes large, the internal bell-shaped hollow metal spheres 1 will be crushed little by little, so that the shock absorbing structural material 5 will be deformed over time and will not be crushed at once. As described above, since the shock absorbing structural member 5 exhibits good energy absorption characteristics, the shock absorbing ability can be increased. Therefore, the thickness of the shock absorbing structural member 5 can be reduced, and both the weight reduction and the shock absorbing ability of an automobile or the like can be improved. This effect is the same when the bell-shaped hollow metal sphere 3 is filled.

Next, a method for manufacturing a bell-shaped hollow metal spheres according to Example 1 will be described.

A blank b used in the above manufacturing method will be described with reference to FIG.
The blank b before processing is a substantially elliptical metal plate. This elliptical blank shape is considered effective from the development of the sphere.
The material of the metal as the blank b may be selected from ductility to withstand processing and deformation characteristics at the time of impact pressurization. For example, a steel plate, a stainless steel plate, an aluminum plate or the like is preferably used. The thickness of the blank b is also selected from the same viewpoint as described above, and varies depending on the material and the deformation characteristics to be given. For example, a thickness of 0.05 to 0.3 mm is preferable.

The elliptical shape of the blank b is basically determined by the major axis dimension h and the minor axis dimension w, but this may be selected to a dimension that does not cause wrinkles depending on the processing method and compatibility with the die and punch used. Furthermore, the curvature radii R ₁ , R ₂ , and R _{3 of} the curved portion may be selected so that wrinkles and the like do not occur due to compatibility with the processing method and processing equipment. The shape of the small holes h of the opening can be controlled by selecting the radius of curvature R _2. For example, if brought closer the shape to a straight line by increasing the radius of curvature R _2, the small hole h is closer to a circle. When inflated by reducing the radius of curvature R ₂ in the opposite, small hole h is a small irregular holes.

Next, the press working method will be described.
The manufacturing method according to the bell-shaped hollow metal sphere of the present invention basically includes a deep drawing process, a mouth closing process, and a finishing process. The three production methods will be described below, but the production method is not limited to the following three production methods as long as the above steps are included.

First Manufacturing Method FIG. 6 shows a first manufacturing method and shows a manufacturing process for producing a bell-shaped hollow metal sphere having a diameter of 5 mm. The process is divided into three stages, and includes a deep drawing process I, a mouth closing process II, and a finishing process III.

  The deep drawing step I uses a deep drawing device 10 including a die 11, a punch 12 and a wrinkle presser 13. The die 11 has a hole 15 having an inner diameter of 5 mm. The punch 12 has a diameter of 4.8 mm and a hemispherical tip. The wrinkle presser 13 is a flange-like member having a hole 16 having an inner diameter of 6 mm. The die 11 is fixed, and the punch 12 and the wrinkle presser 13 are driven by hydraulic pressure or the like. The center of the blank b is placed on the hole of the die 11, and the blank b is fixed on the die 11 with the crease presser 13. Next, the punch 12 is pressurized until the blank b comes off from the wrinkle presser 13.

The mouth closing process II uses a mouth closing device 20 including a die 21 and a punch 24. The die 21 has a substantially hemispherical recess 22 formed on the upper surface. The punch 24 includes a pin 25 and a mouth closing guide 26 protruding outside the pin. The mouth closing guide 26 is an umbrella-shaped member.
In the deep drawing step I, a flat blank b is formed in a tulip-shaped tulip-shaped body b ₁ which is bent at both edges in the short axis direction and rises at both ends in the long axis direction. The tulip-shaped molded body b ₁ is placed on the die 21 of the mouth closing device 20, and the pins 25 of the punch 24 are inserted between both ends of the molded body b ₁ and further pressurized. By this pressurization, the mouth closing guide 26 brings the both ends of the molded body b ₁ closer to each other, and by further processing, the entire edges of the molded body b approach each other to form a bowl-shaped ridge-forming form b ₂ . In order to avoid buckling of the material in this mouth closing process, a device such as performing the mouth closing process II in two stages is also required depending on circumstances.

In the finishing step III, a finishing device 30 including a lower die 31 and an upper die 34 is used. The lower die 31 has a hemispherical recess 32 formed on the upper surface. The upper die 34 has a hemispherical recess 35 formed on the lower surface. The recess 32 and the recess 35 are formed in a spherical shape with the upper and lower dies 31 and 34 in close contact with each other.
Vase formed form b ₂ formed in step II closing the mouth is placed on the lower die 31, the upper die 34 will be pressurized, fountain formed form b ₂ is formed into a spherical shape. In this case, the shape of the pot forming feature b _2, but including biting or wrinkles to between upper and lower molds is likely to occur, by the proper initial blank configuration, it is possible to prevent these drawbacks .

By precisely managing the amount of material in the finishing step III, a bell-shaped hollow metal sphere close to a true sphere with a highly accurate size and shape can be obtained. However, both end portions of the fountain formed form b ₂ because not bonded completely, so that the opening 1b remains. The shape of the opening portion 1b, as shown in FIG. 1 or FIG. 2 is a bell-shaped hollow metal spheres across the elongated slit s with a circular or small hole h in Examples 1 and 2.

Second Manufacturing Method FIG. 7 shows a second manufacturing method and shows a manufacturing process for producing a bell-shaped hollow metal sphere having a diameter of 5 mm. The process is divided into three stages, and includes a deep drawing process I, a mouth closing process II, and a finishing process III.

The deep drawing process I uses a deep drawing device 40 including a die 42, a punch 43 and a wrinkle presser 44.
The die 42 has a hole 45 having an inner diameter of 5 mm, and an upper end portion of the hole 45 is provided with a round 45r. The punch 43 has a diameter of 4.8 mm and a hemispherical tip. The wrinkle presser 44 is a flange-like member having a hole 46 having an inner diameter of 5.2 mm. The die 42 is fixed, and the punch 43 and the wrinkle presser 44 are driven by hydraulic pressure or the like.
The center of the blank b is placed on the hole 45 of the die 42, and the blank b is fixed on the die 42 with the crease presser 44. Next, the punch 43 is pressurized until the blank b comes off the wrinkle presser 44.

The mouth closing process II uses a mouth closing device 50 including a die 51 and a punch 54. The die 51 has a substantially hemispherical recess 52 formed on the upper surface. The punch 54 includes a pin 55 and a mouth closing guide 56 that protrudes to the outside of the pin. The mouth closing guide 56 is an umbrella-shaped member.
In the deep drawing step I, a flat blank b is formed in a tulip-shaped tulip-shaped body b ₁ which is bent at both edges in the short axis direction and rises at both ends in the long axis direction. The tulip-shaped molded body b ₁ is placed on the die 51 of the mouth-closing device, and the pins of the punch 54 are inserted between both ends of the molded body b ₁ and further pressurized. By this pressurization, the mouth closing guide 56 brings the both ends of the molded body b ₁ closer to each other. By this processing, all the edges of the molded body b ₁ approach each other to form a cocoon-shaped ridge forming body b ₂ .
In this mouth closing process, in order to avoid buckling of the material, it is necessary to devise such as performing the mouth closing process II in two stages.

In the finishing step III, a finishing device 60 including a lower die 61 and an upper die 64 is used. The lower die 61 has a hemispherical recess 62 formed on the upper surface. The upper die 64 has a hemispherical recess 65 formed on the lower surface. The recess 62 and the recess 65 are formed in a spherical shape with the upper and lower dies 61 and 64 in close contact with each other.
Vase formed form b ₂ formed in step II closing the mouth is placed on the lower die 61, the upper die 64 will be pressurized, fountain formed form b ₂ is formed into a spherical shape. Since molded from pot formed form b ₂ to the spherical does not occur buckling process may be once.
This also by the second production method, a sphere close to a true sphere size and shape is finished with high accuracy, bell-shaped hollow metal balls of Examples 1 and 2 openings remain in the partition walls is obtained.

Third Manufacturing Method FIG. 8 shows a third manufacturing method. The process is divided into three stages, which are a deep drawing process I, a mouth closing process II, and a finishing process III. The deep drawing process I may use the first manufacturing method or the second manufacturing method. In this manufacturing method, the mouth closing process and the finishing process are simultaneously performed by the mouth closing finishing device 70.

The mouth closing device 70 is configured as follows.
The lower die 71 has a hemispherical recess 72 formed on the upper surface. The upper die 74 has a hemispherical recess 75 formed on the lower surface. The blank holder 76 has a hole 77 for holding the tulip shaped body b ₁ and is supported by a spring 78. Since the hole 77 has a vertical wall surface, it is possible to prevent biting and buckling of the molded body b ₁ during pressurization.

When the upper die 74 is pushed down, the blank holder 76 is pushed down, and the tulip-shaped body b ₁ is sandwiched between the upper die 74 and the lower die 71. The recess 72 and the recess 75 are formed in a spherical shape with the upper and lower dies 71 and 74 in close contact with each other. For this reason, the tulip shaped body b ₁ is formed into a spherical shape. Molded from the tulip-shaped molded body b ₁ to the spherical so as not to cause buckling, sometimes processes that need to devise such performed twice.
This also by the third production method, a sphere close to a true sphere size and shape is finished with high accuracy, bell-shaped hollow metal balls of Examples 1 and 2 openings remain in the partition walls is obtained.

The bulge processing method for producing the bell-shaped hollow metal sphere of the reference example is as follows .
In FIG. 9A, reference numeral 80 denotes a bulge die, which is composed of an upper die 81 and a lower die 82 which are divided in half. Each die 81, 82 is formed with a hemispherical cavity 83 and a cylindrical holding portion 84. A metal cylindrical member P is inserted into the mold. And the rubber material 85 is put in the cylindrical member P, and it pressurizes to the axial direction with the punches 86 and 87 from the both ends. In this way, the portion facing the cavity 83 expands radially outward, and a spherical portion is completed.
Next, as shown in FIG. 3C, the hollow member taken out from the mold has the spherical portions 3 ′ and the cylindrical portions 4 ′ alternately connected. Therefore, when the cylindrical portion 4 is cut, two holes h are formed. A sphere that is centrosymmetric is created.

  Further, as shown in FIG. 5B, the same mold 80 is used, and a high pressure liquid Lg or gas is introduced into the inside of the metallic cylindrical member p for pressurization, and the portion facing the cavity is made spherical. It may be inflated. Even if the hollow member obtained by this method is cut as shown in FIG. 3C, the bell-shaped hollow metal sphere 3 in which the two small holes h are centrosymmetric is obtained.

Next, the mechanical characteristics of the bell-shaped hollow metal sphere of the present invention were investigated by a compression test.
In the experiment shown in FIGS. 10 and 11 were prepared Example 1 and Comparative Example 1-3.
(Example 1)
Example 1 is a bell-shaped hollow metal ball 1 in FIG. 1, the molded body density of 0.657g / cm ^3. Blank b is thickness of 0.1mm was used, the long axis h is 13.5 mm, minor axis w is a steel sheet of 7.5 mm, the basic oval blank of Example 2 to be described later, by increasing the curvature radius R ₂ The shape was made close to a straight line and the long axis was extended at the same time. A photograph is shown in the center of FIG.
(Example 2)
Example 2 is a bell-shaped hollow metal ball 2 in FIG. 2, the molded body density of 0.716 g / cm ^3. The blank b used is a thin steel plate having a thickness of 0.1 mm, a long axis h of 12.5 mm, and a short axis w of 7.5 mm, and has an elliptical shape. A photograph is shown on the left side of FIG.
(Example 3)
Example 3 is a hollow metal sphere shown on the right side in FIG. 10, the molded body density of 0.71 g / cm ^3. Blank b thickness 0.1 mm, long axis h using the 13 mm, minor axis w is a steel sheet of 7.5 mm, and a small shape of the curvature radius R ₂ for realizing the small spheres of the opening portion.
(Comparative Example 1)
The sphere of Comparative Example 1 is a sphere made from a metal powder by a sintering method, and is a hollow metal sphere that is not formed with an aperture and is hermetically sealed. The specific gravity of the hollow sphere is 0.51 g / cm ³ .

Experiment (1)
A large number of hollow metal spheres of Examples 1 to 3 and Comparative Example 1 were filled in a cylindrical can, and the compressive strength was measured under the same conditions. The results are shown in FIG.

As shown in FIG. 11, Examples 1-3 and Comparative Example 1 are both after showing the load increases initially, since it is progressing compressive deformation at a substantially constant stress, the absorption characteristics of the compression energy is I know it ’s good. Further, the range of the compression ratio in the constant stress as compared to Comparative Example 1, longer towards the Examples 1-3 shows better properties. In particular, Example 1 having a circular small hole h is a constant stress portion longest, has become slower than the sharp edge of stress, it can be seen that show good energy absorption characteristics.

Was filled with multiple hollow metal balls in this experiment (1) in sealed cans, when compressing the multiple hollow metal balls as such structure, Comparative Example 1 having no apertures Example 1 It can be seen that the load is high at a compression rate lower than ~ 3. In other words, the first to third embodiments having an opening have a large room for crushing while the load gradually increases. This load between the inside of the sphere will collapse - until even the compression ratio are the same, it of Examples 1 to 3 in which room for opening is gradually crushed exists goes collapsed completely This means that the shock absorption capacity is high. From the above, it can be said that the bell-shaped hollow metal sphere of the present invention has a higher impact absorption capacity than the hollow metal sphere without the opening.

Experiment (2)
Next, an experiment was conducted to confirm the presence or absence of direction dependency.
The compression test was conducted three directions as shown in FIG. 12 (A) relative to bell-shaped hollow metal spheres 2 of Example 2. The h direction is the direction in which the slit s is compressed from above and below. The direction w ₁ is a direction perpendicular to the longitudinal direction of the slit s, and the direction w ₂ is compressed along the longitudinal direction of the slit s.

The result of the compression test is shown in the load-compression ratio curve in FIG.
In any of the h direction, the w ₁ direction, and the w ₂ direction, the load gradually increases as the compression rate increases, and the basic tendency is the same in the three directions. However, the range compression ratio is of 0.6 to 0.9, high load h direction, a load of w ₁ direction intermediate, but w ₂ direction of compression is lowest load, which is the length direction of the slit s It is thought that it is easy to deform because it follows.
Therefore, it can be seen that some direction dependency is exhibited when the compression ratio is in the range of 0.6 to 0.9.

However, what is important is that all the compressions in the three directions h, w ₁ , and w ₂ gradually increase in direct proportion to the load until the compression ratio reaches 0 to 0.8. During this time, the hollow metal sphere gradually collapses, indicating that there is still space inside. While the compression ratio exceeds 0.8 and reaches 1, the load increases rapidly. This is due to the fact that there is almost no gap. In other words, while there are spaces or gaps in the bell-shaped hollow metal sphere, the sphere gradually collapses in proportion to the magnitude of the load, and even if there is some direction dependence in the collapse method, Specifically, this means that the impact load can be absorbed over time regardless of the direction of the slit 5. Therefore, the bell-shaped hollow metal sphere of the present invention has a good shock absorbing ability, and particularly when the bell-shaped hollow metal sphere is randomly filled in a sealed space and used, the direction dependency of the slit is low. It can exhibit high shock absorbing ability without manifesting.

  The bell-shaped hollow metal sphere of the present invention can be used for a shock absorbing structural material used for a hollow member, for example, a circular tube, a hat material, a square tube, an automobile frame, a bumper, a building beam, a column, etc. It is.

(A) Figure is an external view of a bell-shaped hollow metal ball 1 according to Example 1, (B) Fig. Is a cross section B-B of (A) and FIG. (A) Figure is an external view of a bell-shaped hollow metal ball 2 according to Example 2, (B) Fig. Is a cross section B-B of (A) and FIG. (A) The figure is an external view of the bell-shaped hollow metal sphere 3 as a reference example , and (B) the figure is a BB cross section of the figure (A). It is use condition explanatory drawing of the bell-shaped hollow metal sphere of this invention. It is a top view of the blank used for the manufacturing method of the bell-shaped hollow metal sphere in this invention. It is explanatory drawing of the 1st example of the press working method of a bell-shaped hollow metal sphere. It is explanatory drawing of the 2nd example of the press processing method of a bell-shaped hollow metal sphere. It is explanatory drawing of the 3rd example of the press processing method of a bell-shaped hollow metal sphere. It is explanatory drawing of the bulge processing method of a bell-shaped hollow metal sphere. It is a photograph of a hollow metal ball of Examples 1, 2, 3,. It is a graph showing the results of compression tests of Examples 1, 2, 3,. (A) illustrates the figure that shows the pressurizing direction of the pressure test of the bell-shaped hollow metal ball of Example 2 is a graph showing the (B) drawing the results of compression tests.

DESCRIPTION OF SYMBOLS 1 Hollow metal sphere structure 5 Shock absorbing structural material 10 Deep drawing device 20 Mouth closing device 30 Finishing device 40 Deep drawing device 50 Mouth closing device 60 Finishing device 70 Mouth closing device b Blank b ₁ Tulip-shaped molded body b ₂壺Formation

Claims (2)

It is a metal ball for shock absorption that is gradually crushed by pressurization,
A hollow sphere obtained by curving a thin metal plate to form a spherical partition,
An opening is formed in the partition wall,
The shock-absorbing bell-shaped hollow metal sphere, wherein the opening portion is composed of two small holes and a slit connecting them . An impact-absorbing structural material, wherein the hollow structure is filled with the bell-shaped hollow metal sphere of claim 1.