JP2013043439A - W-shaped or corrugated hollow structure material and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorbing member capable of easily and efficiently allowing longitudinally-repeated bend forming and having sufficient shock absorbing power.SOLUTION: A hollow structure material is configured by using a hollow structure sheet material 10 that surface materials 2a, 2b formed of thermoplastic resin sheets are bonded to both surfaces of a core material 1 formed by heat sealing with hollow frustum-shaped convex parts 13 protruded from the thermoplastic resin sheets 1a, 1b which abut on each other. The hollow structure sheet material is bent and formed into the longitudinally-repeated W-shaped or a corrugated form.

Description

  The present invention relates to a W-shaped or corrugated hollow structure material and a method for manufacturing the same.

Various measures have been taken for the body of an automobile to have a vehicle body structure that can absorb impact energy when an impact is applied to the body from the outside.
For example, a front side member that is a part for increasing the strength and rigidity of the front part of the vehicle body, a side sill that is a frame that forms both sides of the vehicle body, directly below the left and right doors, and further a body behind the passenger seat A monocoque structure (stressed skin structure or tension structure) is a structure in which a strength member consisting of a cylindrical body such as a rear side member, which is a skeleton, is arranged in a longitudinal direction at a key point of the vehicle body and stress is applied to the vehicle body and the outer plate of the machine body. It is also referred to as a shell structure.) In the event of a collision, the impact energy loaded by the collision is absorbed by using these strength members as impact absorbing members to ensure the safety of the passenger.

  In recent years, a crash box has been used as one of shock absorbing members of automobiles. For example, the crash box is composed of a cylindrical body having a closed cross-sectional shape generally having an overall length of about 80 to 300 mm, and supports the bumper reinforcement while the front end members of the left and right front side members and the left and right rear side members are It is detachably attached to the rear end. Usually, two crash boxes are arranged in the front-rear direction of the vehicle body, one for each bumper reinforcement.

  The crash box has an impact energy that is impacted by a plastic buckling deformation and collapsing in a bellows-like manner over the front and rear side members that form the body shell due to the impact load input to the bumper reinforcement during a collision. As a result, the body shell is prevented from being damaged to reduce the repair cost at the time of a light collision, and the impact energy is effectively absorbed together with the side members to protect the occupant.

  Crash boxes that are cylindrical bodies are, for example, welded to two components, which are half-finished products formed by pressing thin steel plates, hydroformed to hollow pipes, and further to aluminum alloy materials It is manufactured into a predetermined shape by performing hot extrusion or cold extrusion.

Patent Document 1 proposes a crash box composed of a metal cylinder having a rectangular basic cross-sectional shape.
Further, in Patent Document 2, as a vehicle body structure capable of buckling deformation with respect to an impact load applied from the front end side of an automobile, a metal cylindrical frame member and a substantially parallel axis direction of the cylindrical frame member are disclosed. First reinforcing fibers arranged in various directions, and second reinforcing fibers that intersect with the first reinforcing fibers and are arranged in a direction substantially perpendicular to the axial direction of the cylindrical frame member. A vehicle body structure having a fiber reinforced resin layer attached thereto is disclosed.
And as a most suitable reinforced fiber resin, a matrix is an epoxy resin and carbon fiber (carbon fiber) is mentioned as a reinforced fiber.

  Further, Patent Document 3 includes a hollow energy absorbing member made of fiber reinforced resin as a vehicle body constituting member and an indenter having an outer diameter portion larger than the inner diameter of the energy absorbing member, and the indenter absorbs energy in the event of a vehicle collision. There has been proposed an energy absorption structure for an automobile that breaks into a member. A resin (for example, epoxy resin) reinforced with carbon fiber is described as the fiber reinforced resin.

On the other hand, in Patent Document 4, in a bumper beam for an automobile, at least one core disposed between two floor plates, a front side floor plate and a rear side floor plate made of a metal material, and provided at each end of the core. And an energy absorber formed by a hollow body made of a metal material connected to the front side floor plate or the core, and a ratio between an elastic limit value and a breaking stress of the metal material of the hollow body of the core and the energy absorber is predetermined. Bumper beams of the value of have been proposed.
Further, Patent Document 5 proposes a resin molded product designed to improve the amount of energy absorption by providing a thin portion on the rib of the resin molded product. In the resin molded product of Patent Document 5, the rib of the resin molded product usually breaks instantaneously, but the rib structure is partially thinned so that the ribs are sequentially broken, and the amount of rib crushing is increased. The amount of energy absorbed by is improved.

  On the other hand, in Patent Document 6, a surface made of a thermoplastic resin sheet is provided on both surfaces of a core material that is heat-sealed in a state in which the hollow frustum-shaped convex portions projecting from the thermoplastic resin sheet face each other. A terminal structure and a terminal processing method of a hollow structure plate material bonded with materials have been proposed.

JP 2011-51581 A JP 7-165109 A JP 2005-170299 A Special table 2003-503272 gazette Japanese Patent Laying-Open No. 2005-271383 JP 2010-58482 A

Since the crash box described in Patent Document 1 is a cylindrical body having a special cross-sectional shape, it is said that it can generate a bellows-like plastic buckling deformation that is continuously stable against an impact load, but is a metal. A) Large (heavy) b) Manufactured by metal processing or sheet metal processing, so there is a restriction on the degree of freedom of shape, c) Corrosion requires painting, d) Low vibration damping Therefore, there are problems such as large vibration and noise.
The bumper beam of the automobile of Patent Document 4 is a metal material in which the core material is a continuous material of alternating protrusions and recesses extending at right angles to the longitudinal axis, and is commercially available as described in Non-Patent Document 1. Since the crash box is essentially made of metal, there is a problem similar to that of Patent Document 1.

  On the other hand, in the vehicle body structure in which the metal frame member and the carbon fiber reinforced resin layer described in Patent Document 2 are attached, and in the energy absorption structure of the automobile described in Patent Document 3 using the carbon fiber reinforced resin (CFRP), a) high in price, b) limited in the degree of freedom of shape because it is manufactured by carbon fiber resin impregnation molding, c) because it has the property of being pulverized at the time of destruction, there is a health hazard due to dusted carbon fiber, d) Since vibration attenuation is small, vibration and noise are large, e) difficult to recycle, and f) performance is greatly degraded due to minute damage, but there is a problem that there is no simple and effective method for detecting damage.

Moreover, in the resin molded product provided with the rib of patent document 5, since the direction of a rib is one direction, the capability to deform | transform into all directions at the time of an impact and to absorb energy is insufficient.
On the other hand, the thermoplastic resin hollow plate terminal processing method described in Patent Document 6 is a terminal sealing method for preventing dust and the like from entering the inside from the end of the hollow plate. A technique for bending or bending is not disclosed.

In view of the above problems, the present inventor has intensively studied the configuration of a shock absorbing member having sufficient shock absorbing power, and as a result, a specific thermoplastic resin hollow structure plate is bent and shaped into a special shape to obtain a thickness. The present invention has been completed by finding that a high impact absorption characteristic can be obtained when the direction surface is a surface to which an impact is applied. In addition, the inventors have intensively studied a bending method for obtaining the shock-absorbing member subjected to bending shaping according to the present invention, and have completed the invention of the bending method.
That is, the present invention provides the following (1) to (3).

(1) A surface material made of a thermoplastic resin sheet is bonded to both surfaces of a core material that is heat-sealed in a state where the hollow frustum-shaped convex portions protruding from the thermoplastic resin sheet face each other. A hollow structure material using a hollow structure plate material, wherein the hollow structure plate material is bent and shaped into a W shape or a wave shape that repeats in the longitudinal direction.
(2) An impact-absorbing member using the hollow structure material according to (1), wherein a surface in the thickness direction is a surface (top surface) to which an impact is applied.
(3) A surface material made of a thermoplastic resin sheet was bonded to both surfaces of a core material that was heat-sealed in a state where the hollow frustum-shaped convex portions protruding from the thermoplastic resin sheet were butted together. A method for producing a hollow structure material for bending a hollow structure plate material, wherein the production method comprises a temperature corresponding to the bending portion of the hollow structure plate material at a temperature at which the surface material can be thermally deformed below the melting point of the thermoplastic resin. It is characterized in that, after that, a jig having a shape corresponding to the thickness of the hollow structural plate is brought into pressure contact with both sides of the hollow structural plate, subjected to bending, and cooled and cooled in the jig. A method for producing a hollow structure material.

The hollow structural material of the present invention is lightweight, and when it is used as an impact absorbing member, since the surface in the thickness direction is a surface to which an impact is applied, the hollow frustum-shaped convex portions (hereinafter referred to as “cones”) arranged periodically. ) And the heat-welded surface in a butt-like manner and the portion where the impact force is first received and then sequentially deformed and propagated, so that a stable impact absorbing force is ensured.
Since the hollow structural material of the present invention is formed by bending the hollow structural plate material into a W shape or a corrugated shape in the longitudinal direction, when it is used as an impact absorbing member, it is buckled by an impact force in units of the bending shape. Even if this occurs, the other units sequentially absorb the impact force, so that the impact absorption force after buckling can be secured over the entire length of the hollow structure plate.
The hollow structural material of the present invention is excellent in productivity and easy to recycle. In addition, since no connection hardware or adhesive is required and no connection hardware is used, there is no need to paint for corrosion protection.
The method for producing a hollow structure material of the present invention can easily and efficiently perform bending shaping that is necessary for the impact absorbing member of the present invention and is repeated in the longitudinal direction.

It is the perspective view which used as a shock absorption member the hollow structure material bend-shaped by the W type by Example 1. FIG. It is the perspective view which used as a shock absorption member the hollow structure material bend-shaped in the waveform. Sectional drawing of the hollow structure board | plate material which comprises the hollow structure material of this invention (A) top side perspective view showing structure of one example of hollow projection sheet having hollow frustoconical convex portion constituting core material of hollow structure plate material, (b) longitudinal sectional view showing structure of convex portion, ( c) It is a lower surface side perspective view. It is a model explanatory drawing of (A) preheating of the W-shaped bending shaping | molding of a hollow structure board | plate material, (B) Heater retreat, and (C) bending shaping. It is explanatory drawing of the preheating state of the hollow structure board | plate material by an example of a bending process apparatus. It is explanatory drawing which shows the state by which the heater retracted | retreated by an example of the bending processing apparatus, and the hollow structure board | plate material was shaped in the W shape with the jig. It is a load-displacement curve of a W-shaped bending shaped shock absorbing member. It is an analysis figure of the deformation mode of the shock absorbing member of the present invention.

[Hollow structure material]
The hollow structural material of the present invention is a surface made of a thermoplastic resin sheet on both sides of a core material that is heat-sealed in a state in which the hollow frustum-shaped convex portions projecting from the thermoplastic resin sheet are butted together. It is a W type or corrugated shape using a hollow structural plate material bonded together, and the hollow structural plate material is bent and shaped into a W shape or a corrugated shape that repeats in the longitudinal direction. In the present invention, bending molding into a W shape means a linear bending molding in which a bending compressive force is applied perpendicularly to the longitudinal direction to any one surface material of a flat hollow structure plate material, It is said that the surface material side facing the linear inner fold corner is tensile-deformed to form the surface material. The shape is accompanied by the thinning of the core and deformation of the core material.
FIG. 1 shows an example in which a hollow structure material formed by bending into a W shape is used as an impact absorbing member. The hollow structural member 100 is formed by bending a hollow structural plate member 10 having a thickness of Tmm into a W shape (zigzag shape) in which five units (unit) length Umm are repeated in a longitudinal direction at a predetermined angle. The impact absorbing member made of the hollow structural material of FIG. 1 has a structure in which an upper part (top) is a surface to which an impact is applied and a buckling force acts in the direction of the stroke S. The thickness T is preferably in the range of 7 to 32 mm, the unit length U is 20 to 80 mm, and the stroke S is 30 to 150 mm. The thickness T is more preferably 9 to 20 mm.
On the other hand, FIG. 2 shows an example in which a hollow structural material formed by bending into a corrugated shape is used as an impact absorbing member. The hollow structural member 101 is bent and shaped into a wave shape that repeats at the wavelength L ₀ , and has no straight corners compared to the W shape (zigzag shape) in FIG. The bend forming part has a gentle R-shaped waveform.
The length L of the hollow structural material corresponds to the length of a portion in which the hollow structural material is stored, such as a crash box or a bumper. Moreover, it arrange | positions so that an impact load may be loaded on the surface (top surface) of thickness T of a hollow structure board | plate material.
The width of the hollow structural material indicated by S in the hollow structural materials 100 and 101 of FIGS. 1 and 2 is determined by how long (stroke) the impact force applied to the thickness surface T is absorbed. . This stroke S is approximately 50 to 150 mm for a bumper beam and approximately 40 to 150 mm for a crash box application.

(Hollow structure plate)
The hollow structural plate material used for the hollow structural material of the present invention is thermoplastic on both surfaces of the core material that is heat-sealed in a state where the hollow frustum-shaped convex portions protruding from the thermoplastic resin sheet are butted together. Ube Nitto Kasei Co., Ltd., which has a structure in which a surface material made of a resin sheet is bonded, can be manufactured by a method for manufacturing a hollow structure plate material disclosed in a pamphlet of WO2003 / 080326. More commercially available hollow structure plates can be used.
A method of manufacturing a hollow structure plate material disclosed in the pamphlet of WO2003 / 080326 introduces two thermoplastic resin sheets into a decompression chamber and surrounds a pair of upper and lower embossing rollers disposed rotatably in the decompression chamber. A plurality of hollow projections are formed on each resin sheet in accordance with the pin shape projecting from both embossing rollers by adsorbing each resin sheet to the surface, and the end surfaces of the hollow projections at the tangential position of both embossing rollers It is a manufacturing method in which a core material is formed by continuously heat-sealing each other, and a surface material made of a thermoplastic resin sheet is heat-sealed on both surfaces of the core material. It has a truncated cone shape or a truncated pyramid shape.
In the present invention, the hollow frustum shape means a hollow frustum shape or a hollow frustum shape, and any of these may be used.
FIG. 3 is a schematic cross-sectional view showing the main part of a hollow structure plate made of thermoplastic resin.
The hollow structure board | plate material which shows a partial cross section in FIG. 3 is the surface on both surfaces of the core material 1 comprised by bonding the convex-part vertices of the two hollow projection sheet | seats 1a and 1b which consist of a thermoplastic resin sheet by heat sealing | fusion. The material 2a and 2b are bonded together.

The material for the hollow protrusion sheet and the surface material is not particularly limited. For example, polyethylene resins, polyolefin resins such as polypropylene resins, copolymers of these comonomers or comonomers and other monomers, polyvinyl chloride, chlorinated polyvinyl chloride, ABS, AAS, AES, polystyrene, Examples include polyethylene terephthalate, polycarbonate, polyamide, polyvinylidene fluoride, polyphenylene sulfide, polysulfone, polyether ketone, and copolymers of these comonomers or comonomers with other monomers. These may be used alone or in combination. Also good. As described above, various thermoplastic resins can be used. However, in consideration of balance with properties such as cost, moldability, physical properties, low temperature resistance, and heat resistance, polyolefin resins are preferable, and polypropylene resins are preferable. Particularly preferred.
Examples of the polyethylene resin include low density polyethylene, high density polyethylene, and linear low density polyethylene. Examples of the polypropylene resin include homopolypropylene, random polypropylene, and block polypropylene.
For the purpose of increasing the rigidity of the hollow protrusion sheet or the surface material, a filler may be blended as an auxiliary material.
The auxiliary material is not particularly limited, but talc, calcium carbonate, and the like are preferable in consideration of the balance with cost, formability, handleability, and the like. Increasing the amount of filler added leads to high costs and specific gravity. Therefore, considering these balances, the amount added is 5 to 30% by mass in the case of talc and 20% in the case of calcium carbonate. It is preferable to be about% or less.
In addition to the filler, an antioxidant, an ultraviolet absorber, an antistatic agent, an antibacterial agent, a flame retardant, a light stabilizer, a lubricant and the like may be added as necessary.

The hollow protrusion sheet constituting the core material of the hollow structure plate constituting the hollow structure material of the present invention will be described in more detail.
The hollow protrusion sheet 1a shown in FIG. 4 (a) has a hollow truncated cone shape in which a plurality of convex portions 13 are regularly provided on one surface of the hollow protrusion sheet base surface, and the lower bottom side is open. In this embodiment, the convex portions 13 are formed by providing the convex portions 13 in a row at predetermined intervals along the longitudinal direction of the main body portion 12, and the convex portion rows 14 are formed as hollow projections. A plurality of rows are provided at predetermined intervals in the width direction of the body sheet base surface 12. It is desirable for the convex portion row 14 to have a so-called staggered shape in which the positions of the hollow frustum-like convex portions in the width direction are shifted from the adjacent convex portion row 14 ′ in order to obtain a plate material with more isotropic properties. . The shape of the hollow frustum may be a hollow frustum shape (not shown). In the following, description will be made by using a hollow frustoconical convex portion.

Each convex portion 13 has a hollow shape having a concave portion 15 opened on the other surface (lower surface) of the hollow projection sheet base surface 12, that is, the lower bottom side, on the inner surface side, and the outer peripheral surface extends from the tip to the root. Each convex part 13 is formed in the same shape and magnitude | size, and it is formed in the truncated cone shape of the taper surface where a diameter increases gradually.
Each recess 15 is formed in a conical space having a tapered surface whose inner surface gradually increases in diameter from the tip (deepest part) to the root (opening end). Each recess 15 is formed in the same shape and size.

The taper angle θ of each convex portion 13 and the taper angle θ of each concave inner surface 15 (shown in FIG. 4B) is preferably within a range of 40 to 80 °, more preferably from the viewpoint of pressure resistance as a core material. It is in the range of 60-80 °. (If the taper angle is less than 60 °, the pressure resistance as the core material may be insufficient, and if the taper angle is 80 ° or more, the thickness of the convex wall surface becomes small, and the pressure resistance is similarly insufficient. there is a possibility.)
In addition, the lower bottom diameter of each convex portion 13 is 3 to 16 mm, the upper bottom portion diameter is 1.5 to 4 mm, the gap interval between adjacent frustoconical convex portions is 10 mm or less, and the height of the convex portion is 3 to 13 mm. Can do.
When the gap interval between adjacent frustoconical convex portions is 10 mm or more, the pressure resistance tends to be insufficient. If the height of the convex portion is 3 to 13 mm, as a hollow protrusion sheet of the hollow structure material, due to the pressure resistance when impact force is applied and the cohesive failure at the thermal fusion portion between the convex portions and the surface material It is preferable in terms of impact absorption.

The thickness of the main body 12 is preferably 0.1 to 1 mm from the pressure resistance of the hollow structure sheet material as the hollow protrusion sheet. If the thickness of the main body portion 12 is less than 0.1 mm, when the plurality of convex portions 13 are formed by molding with a molding machine, there is a possibility that each convex portion 13 cannot obtain sufficient rigidity in a film state. The pressure resistance of the hollow structural plate material as the hollow projection sheet of the core material is insufficient, and the convex portion may be destroyed.
The core material of the hollow structure plate material used in the hollow structure material of the present invention is manufactured by simultaneously molding the two hollow protrusion sheets 1a and 1b and heat-sealing the convex portions 13, and as described above, the core material. 1 can be obtained, for example, by the production method described in the pamphlet of WO2003 / 080326.
As for the dimensional shape, the total thickness is basically twice that of one hollow protrusion sheet.
The two hollow projection sheets need not necessarily have the same size or the same material, and may have different dimensions and different materials. However, when flatness is required as a hollow structural material, if the two hollow projection sheets are of the same size or the same material, they are symmetrical with respect to the neutral axis in the thickness direction. This is preferable because warpage hardly occurs.

The hollow structural plate material constituting the hollow structural material of the present invention has a plane compressive strength of 300 to 3000 kN / m by a flat plate compression test at a load speed of 10 mm / min in accordance with JIS Z 0403-1 from the viewpoint of impact absorption. What is ² can be used.
If the plane compressive strength is in the range of 300 to 3000 kN / m ² , it has pressure resistance as a part of a structural member such as a bumper, and when an impact force is applied, buckling deformation and heat fusion part Impact force can be absorbed by cohesive failure.

The hollow structural material of the present invention is W-shaped or corrugated that repeats in the direction perpendicular to the longitudinal direction (conveying direction = machine direction = MD direction) during continuous production of the hollow structural plate material made of the thermoplastic resin, that is, in the TD direction. It is preferable to perform bending molding from the viewpoint of absorbing performance of impact force accompanying the deformation mode.
Furthermore, the bending forming is particularly preferable from the viewpoint of absorbing performance of higher impact force than the W-shaped bending forming.

Further, it is preferable that both the core material and the surface material of the hollow structure plate material are polyolefin resins from the viewpoints of cost, moldability, physical properties, low temperature resistance, balance with properties such as heat resistance, and the like. Is particularly preferred.
The thickness of the surface material of the hollow structural plate is preferably 0.5 to 3.0 mm, more preferably 0.6 to 2.0 mm, and still more preferably 0.7 mm to 1.5 mm.

[Method for producing hollow structure material]
Next, the bending method of the hollow structure board | plate material used for the hollow structure material of this invention is demonstrated.
FIG. 5 schematically shows the bending method of the present invention, in which (A) shows a state in which the bending portion of the hollow structure plate is preheated by a heater, and (B) shows that the heater is retracted. The state just before bending the hollow structure board | plate material preheated in advance with a jig | tool is shown, (C) is explanatory drawing which shows typically the state shape | molded by the jig. The preheating by the heater described above is performed on the region corresponding to the bending portion of the hollow structure plate material, that is, the region of at least both surface materials on the compression deformation (inner periphery) side and tensile deformation (outer periphery) side by bending. It is heated to a temperature that can be thermally deformed at a temperature lower than the melting point of the plastic resin.After that, a jig having a shape corresponding to the bent shape is pressed on both surfaces of the hollow structural plate material to perform bending. It is characterized by cooling and cooling in a jig.
When heating at least the surface material region to a temperature at which the surface material can be thermally deformed below the melting point of the thermoplastic resin of the surface material, the surface material that undergoes tensile deformation at the time of bending deformation cannot withstand bending deformation and breaks. It is more preferable that the entire portion subjected to bending deformation, that is, the entire thickness of the hollow structural plate including the core material, is heated to such an extent that it can be easily plastically deformed.

  Examples of the jig used for bending deformation include a press mold, etc., and a cooling water circulation device is provided in the mold, and after bending deformation, the temperature is lowered in a state of sandwiching the bent hollow structural material. Those having a function of solidifying are preferable.

  Furthermore, in the bending method of the present invention, in the bending process in which the hollow structural plate material is formed into a W shape that repeats in the longitudinal direction, the bending direction is orthogonal to the longitudinal direction of the hollow structural plate material in accordance with the number and the number of the bending process. A linear (blade-shaped) electric heater arranged in such a manner, and a jig having a predetermined shape corresponding to the shape of bending molding, wherein the electric heater is inserted so as to be able to advance and retract, and the electric heater is used for the hollow structure plate After heating up in a non-contact manner, the electric heater is retracted from the surface of the hollow structural plate, and then bending is performed by pressing the jig against both sides of the hollow structural plate, and then cooling and lowering the temperature in the jig. It can be set as the bending method of a hollow structure board | plate material.

A bending method for forming a W shape will be described with reference to FIGS. FIG. 6 schematically shows a state in which the hollow structure plate 10 is preheated by the bending apparatus 20. A linear (blade-shaped) electric heater 21 is inserted into each of the top and valley portions of the upper jig 22a and the lower jig 22b so as to be able to advance and retreat from the set hollow structure plate 10. The hollow structural plate 10 is heated by the heater 21 group in a non-contact state at a portion (bent portion) that undergoes bending deformation.
Next, the electric heater moves backward from the bent portion of the hollow structural plate material, and the upper and lower jigs move so as to sandwich both surfaces of the hollow structural plate material, and come into pressure contact to form a W shape (a predetermined shape corresponding to the jig 22). Zigzag type), cooled by a jig, and cooled and solidified to W type.
FIG. 7 shows a state where the heat forming and cooling solidification are completed, the upper and lower jigs are moved backward, the forming of the W-type hollow structure material is completed, and demolding is possible.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples at all.

Example 1
[Hollow structure material]
A “twin cone” having a standard thickness of 13.3 mm (manufactured by Ube Nitto Kasei Co., Ltd. (product number: TC12-3010N9)) as a hollow structural plate was cut into a size of 100 mm in the TD direction and 300 mm in the MD direction. A W-shaped hollow structural material shown in FIG. 1 was produced, in which this bending was repeated 5 times at a pitch of 50 mm in the MD direction.
6 and 7 is used as a bending apparatus, and a linear electric heater 21 having a width of 3 mm and a surface temperature controlled to 170 to 175 ° C. is subjected to bending of a hollow structure plate material. Faced in a non-contact state with a gap of 2 mm from the surface material at the position to be heated, heated for 1 minute, then moved the jigs 22a and 22b toward the hollow structure plate while retreating the electric heater 21, and contacted with pressure Then, the hollow structure plate material is sandwiched, and then the jigs 22a and 22b are cooled through a cooling medium at 40 ° C. in the jig to cool and solidify the hollow structure plate material bent and shaped into a W shape. Material 100 was obtained. The resulting W-shaped hollow structural material was subjected to the following impact test in which an impact force was applied to the surface in the thickness direction as shown in FIG.

(Shock test)
The compression test was performed using TCM-5000C manufactured by Minebea as a test device. The compression surface by the indenter is the upper surface in the thickness direction as shown in FIG. 1, and the measurement conditions are a temperature of 23 ° C., a humidity of 50% RH, a compression speed of 10 mm / min. . In addition, the deformation | transformation moving image was recorded on the left end side surface of FIG. The analysis result of the deformation mode by this recording is shown in FIG.
Table 1 summarizes the structure of the hollow structural plate (including the core material and the surface material) and the physical properties of the hollow structural material.

Example 2
Instead of the hollow structure plate material of Example 1 (twin cone: TC12-3010N), a hollow structure plate material (twin cone: TCB9-3010N) having a cone height of 4.5 mm and an overall thickness of 10.4 mm was used. Otherwise, the hollow structure material was obtained by bending into a W shape in the same manner as in Example 1.
Table 1 summarizes the structure of the hollow structural plate (including the core material and the surface material) and the physical properties of the hollow structural material.
Moreover, the load-displacement curve in the impact test of Examples 1 and 2 is shown in FIG.

  From the results of the examples in Table 1, in Example 2, the height of the cone of the core material is set to 4.5 mm, and the entire thickness of the hollow structure plate is reduced, so that the thickness of the cone portion is increased and the hollow structure is formed. Since the bending rigidity of the whole material increased, the absorbed energy was improved by 13% compared with Example 1. From these facts, it was confirmed that a hollow structure material having a higher absorption energy per mass can be obtained by optimal design of the cone of the hollow structure plate material, selection of raw material resin, and the like.

Since the hollow structural material of the present invention ensures stable shock absorption, it is widely used as a hollow structural material for industrial packing materials such as automobile bumper beam core materials, crash boxes, interior materials (pillar trims) and containers. Available.
The method for producing a hollow structure material of the present invention can be used as a bending method that can easily and efficiently perform bending shaping that is necessary for the hollow structure material of the present invention and repeats in the longitudinal direction.

DESCRIPTION OF SYMBOLS 1 Core material 1a, 1b Hollow protrusion sheet | seat 2, 2a, 2b Surface material 10 Hollow structure board | plate material 12 Hollow protrusion sheet | seat base surface 13 The hollow frustum-shaped convex part (convex part) which the bottom bottom side opened
14, 14 'Convex part row 15 Opening part 20 Bending device 21 Electric heater 22a (Upper) Jig 22b (Lower) Jig 100 W type hollow structure material 101 Wave type hollow structure material

Claims (8)

A hollow structural plate material in which a surface material made of a thermoplastic resin sheet is bonded to both surfaces of a core material that is heat-sealed in a state in which the hollow frustum-shaped projections protruding from the thermoplastic resin sheet are butted together A hollow structural material using
A hollow structure material obtained by bending the hollow structure plate material into a W shape or a wave shape that repeats in the longitudinal direction. An impact absorbing member using the hollow structural material according to claim 1,
An impact-absorbing member, wherein a surface in the thickness direction is a surface to which an impact is applied (top surface).   The hollow frustum-shaped convex part of the core material of the hollow structural plate material is a hollow frustum-shaped convex part having a lower bottom diameter of 3 to 16 mm, an upper bottom diameter of 1.5 to 4 mm, a height of 3 to 13 mm, and an adjacent cone The gap interval between the trapezoidal convex portions is 10 mm or less, the sheet thickness is 0.1 to 1 mm, the taper angle of the truncated conical convex portion is 60 to 80 degrees, and the total thickness T is 7 to 32 mm. Shock absorbing member.   The impact absorbing member according to claim 2 or 3, wherein the bending shaping is a W-shaped or wave-shaped bending shaping which is repeated in the longitudinal direction of the hollow structural plate material.   The impact absorbing member according to claim 3, wherein the bending molding is a W-shaped bending molding.   The shock absorbing member according to any one of claims 2 to 4, wherein the thermoplastic resin of the core material and the surface material is a polyolefin resin. A hollow structural plate material in which a surface material made of a thermoplastic resin sheet is bonded to both surfaces of a core material that is heat-sealed in a state in which the hollow frustum-shaped projections protruding from the thermoplastic resin sheet are butted together A method of manufacturing a hollow structure material that bends, wherein the manufacturing method heats a region corresponding to a bending portion of the hollow structure plate material to a temperature that can be thermally deformed below the melting point of the thermoplastic resin of the surface material. Then, a hollow structure characterized in that a jig having a shape corresponding to the thickness of the hollow structure plate material is subjected to pressure contact with both surfaces of the hollow structure plate material, bending is performed, and cooling / cooling is performed in the jig. A method of manufacturing the material.   The bending process is a bending process in which the hollow structural plate material is shaped into a W shape that repeats in the longitudinal direction, and is arranged so as to be orthogonal to the longitudinal direction of the hollow plate material, in accordance with the number and location of the bending process. A straight electric heater and a jig having a predetermined shape corresponding to the shape of the bending molding are inserted through the electric heater so that the electric heater can be moved forward and backward, and the electric heater is brought close to the hollow structural plate material and heated without contact. 8. The hollow according to claim 7, wherein the electric heater is retracted from the surface of the hollow structural plate, and thereafter the jig is pressed and brought into contact with both surfaces of the hollow structural plate to perform bending, thereby cooling and lowering the temperature in the jig. Manufacturing method of structural material.