JP3454420B2 - Impact energy absorbing member with prismatic outer shape - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION Transportation means such as humans, animals, dangerous goods, etc. are
It is equipped with a shock absorbing structural member that absorbs the shock energy. The present invention relates to this shock absorbing structural member, and more particularly to a shock energy absorbing member that absorbs this energy irreversibly in its specific failure mode, and in particular, is obtained by injection molding of a thermoplastic resin.

[0002]

2. Description of the Related Art As a shock absorber (for example, a support member for a bumper or a support member for a handle shaft) for cushioning a shock of a moving body such as a vehicle or a ship colliding with each other or a stationary body such as a quay or a pier, an aircraft. , As a shock absorber to cushion the impact when a helicopter or elevator lands due to a malfunction, or to cushion the impact when a nuclear fuel transportation device (cask) or a container containing radioactive waste (canister) falls As a shock absorber, each transportation means is equipped with an impact energy absorbing member that irreversibly absorbs impact energy.

Conventionally, as these shock absorbing structural members, "a shock absorbing structural member using a liquid buffer mechanism utilizing the principle of converting and consuming shock energy into friction energy and then into heat energy", "impact energy of plastic of metal Those using a specific shape structural body such as a tubular shape or a honeycomb shape made of a specific strength metal material, which uses the principle of converting into consumption by deformation and consumption. "

However, although these shock absorbing structural members are excellent in shock absorbing property themselves, (1) the structure is complicated and they are liable to malfunction (mechanical, corrosion, etc.) (2) The manufacturing cost is high (high processing, high energy). Consumption manufacturing process, etc.) (3) There are problems such as heavy (use of metal materials, etc.), and improvement in these points is desired.

In recent years, there has been an increasing demand for space-saving and light-weight impact absorbing structural members mounted on vehicles, aircrafts, elevators, etc., along with the trend toward lighter weight and higher performance of these transporters. In order to meet this demand, impact energy absorbing members having a high impact energy absorbing amount per unit volume or unit weight have been studied from the both aspects of material and structure. Further, these transporters have a strong tendency to reduce costs, and from this point of view, the impact energy absorbing member is being studied from the viewpoint of both material and structure.

With these studies, the above-mentioned drawbacks of the conventional impact energy absorbing member have come to be recognized as an extremely serious problem more than ever.

In order to overcome these problems, the development of impact energy absorbing members made of fiber-composite synthetic resin has come to be carried out, focusing mainly on the development of vehicle-mounted impact energy absorbing members. .

For example, in Japanese Unexamined Patent Publication No. 6-264949, a short fiber reinforced hollow cylindrical body in which the thickness gradually increases from the first end to the second end and the first end is curved outward in the radial direction Is proposed. This hollow cylinder solves the above problems (1) and (3) by using reinforcing fibers as short fibers, and also has the above problem (2) because it can be manufactured by ordinary injection molding. Has been resolved.

Here, in order for the impact energy absorbing member to effectively function, it is important to devise so that a sudden load is not generated particularly during collision deformation. For example, the cylinder does not buckle or the like during the fracture, and continuous stable fracture continues until the final stage, whereby a large amount of energy is absorbed.

In the above publication, for example, by adopting a structure in which the wall is gradually thickened from one end to the other end of the hollow cylindrical body, stable destruction of the cylindrical body is continued. Here, so-called change in wall thickness in the axial direction of the cylinder is used as a trigger for destruction.

However, since the wall thickness gradually increases, the bottom of the cylinder has a considerable thickness, and as a result, the weight of the entire cylinder increases.

Most shock absorbers for installing the impact energy absorbing member have a flat surface. However, since the hollow cylinder described in the above publication has curved side surfaces, it is difficult to mount the shock absorber on the flat portion of the shock absorber. there were. Furthermore, since it is a curved surface, it is difficult to attach the shock absorber mounting member.

[0013]

In view of the above-mentioned problems of the prior art, the present invention provides a shock energy having a simpler structure, capable of continuing stable self-destruction, and having a good mountability with a shock absorber related member. An object is to provide an absorbing member.

[0014]

The above objects have been achieved by the impact energy absorbing member described below. That is, the first impact energy absorbing member of the present invention is an aromatic
Contains a compound containing a ring as the main constituent monomer,
A thermoplastic resin containing the monomer in the main chain
(Hereinafter referred to as "aromatic ring-containing thermoplastic resin")
Comprising a tubular body having a plane outside surface a cylindrical hollow thermoplastic resin composition formed by injection molding, and the thermoplastic
The resin composition is tilted with respect to the axial direction of the tubular body.
It A second impact energy absorbing member of the present invention is the first absorbing member, wherein the outer shape of the tubular body is a prism. According to a third impact energy absorbing member of the present invention, in the first or second absorbing member, the aromatic ring-containing thermoplastic resin is supported.
-Motropic liquid crystal polymer.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The impact energy absorbing member of the present invention (also referred to as an impact energy absorbing tubular body) is usually made of resin, and is attached to a shock absorber in such a state that an impact is applied from above and below in the axial direction of the cylinder. It is used after being used.

The use form of the impact energy absorbing member of the present invention is not limited. For example, they can be used alone or in combination, and other impact energy absorbing members,
It may be used in combination with a structural member or the like.

1 and 2 are a perspective view and a perspective view, respectively, of one embodiment of the impact energy absorbing member of the present invention. The impact energy absorbing member 1 shown in the figure has a hollow cylinder inside, while the outer shape is a prism.

Since many shock absorbers have a flat surface, the impact energy absorbing member of the present invention having a flat surface on the outer surface can be easily attached to such a shock absorber. Further, compared to a curved surface, it is easier to mount or mold a shock absorber mounting member such as a protrusion or a depression on a flat surface.

The outer shape of the impact energy absorbing member of the present invention may be any other shape as long as the position where the shock absorber related member is attached is flat, but it is usually a prism, and in particular 3 Approximately 10 prisms are suitable because they are easy to manufacture. When the outer shape of the impact energy absorbing member of the present invention is a polygonal prism, the upper surface (transverse cross section) thereof has a circular inner circumference and a polygonal outer circumference. In such a tubular body, the wall thickness near the apex of the polygon and the wall thickness at the sides are different, and the orderly nonuniformity of this thickness causes cracking in the tubular body when an impact is applied. It becomes a trigger to induce. That is, since stress is likely to concentrate in the thin portion, cracks are likely to occur, while the thick portion improves the buckling resistance of the tubular body. Buckling is an undesirable form of failure that reduces the rate of impact energy absorption.

The impact energy absorbing member of the present invention may be provided with a shock absorbing device mounting member such as a bolt, a protrusion or a recess, a lid or a bottom which can be fixed to the main body as a breakage trigger, in the tubular main body.

Next, the material and manufacturing method of the impact energy absorbing member of the present invention will be described. Usually, the shock absorbing member of the present invention is made of resin, and it is preferable to manufacture it by injection molding using a mold having a cavity in the shape of the member. In the case of injection molding, any thermoplastic resin can be used as the material resin.

The constituent material of the impact energy absorbing tubular body of the present invention is preferably oriented in a direction different from the axial direction of the tubular body. That is, as the orientation direction of the material such as the resin is inclined with respect to the axial direction of the cylinder and is closer to the radial direction of the cylinder,
The tubular body has increased mechanical strength against stress from the axial direction.

In order to orient the material such as the resin obliquely with respect to the axial direction of the cylinder, it is preferable to injection-mold the material using a rotating mold member. Since the impact energy absorbing tubular body of the present invention has a cylindrical hollow inside and a polygonal outer shape in general, it is a cylindrical inner core die to be rotated, while a polygonal hollow outer die forming the outer shape is rotated. The mold is fixed.

When the orientation of the resin is utilized by injection molding using a rotating core die, a thermoplastic resin having a property of exhibiting a high elastic modulus by the orientation is preferable.

A typical thermoplastic resin exhibiting a high elastic modulus by orientation contains a compound containing an aromatic ring as a main constituent monomer, and the monomer is contained in the main chain and has a rigid molecular structure. There are things. Specific examples of the monomer compound having an aromatic ring as the main constituent monomer include monomers such as bisphenol A, metaxylylenediamine, terephthalic acid, 2,6-naphthalenedicarboxylic acid and dihydric phenol. .

A compound containing these aromatic rings is contained as a main constituent monomer, and the monomer is contained in the main chain,
The thermoplastic resin having a rigid molecular structure is easily available as a commercially available resin. For example, a polyamide having metaxylylenediamine as a main constituent monomer (for example, MXD nylon resin (trade name) manufactured by Mitsubishi Gas Chemical Co., Inc.); a polyester having terephthalic acid as a main constituent monomer (for example, polyethylene terephthalate resin, Polybutylene terephthalate resin); Polyester containing 2,6-naphthalenedicarboxylic acid as a main constituent monomer (for example, P
Polycarbonate and polyester containing bisphenol A as a main constituent monomer; polyphenylene sulfide; polyphenylene oxide; polysulfone; polyarylate containing dihydric phenol as a main constituent monomer (for example, U polymer resin manufactured by Unitika Ltd. Name)); polyetherketone; polyetheretherketone; p-hydroxybenzoic acid, hydroxynaphthoic acid, a dihydric phenol or a biphenol as a main constituent monomer, and a thermotropic liquid crystal polymer which exhibits optical anisotropy when melted (for example, Sumika Super (trade name) manufactured by Sumitomo Chemical Co., Ltd., Zaider (trade name) manufactured by Amoco, Zenite (trade name) manufactured by DuPont, Vectra (trade name) manufactured by Hoechst-Ceraneze, and Toray Siberus (trade name), manufactured by Unitika LODRUN (trade name)), and the like. The thermoplastic resins may be used alone or in a mixture of two or more.

Among these resins, thermotropic liquid crystal polymer (hereinafter, also referred to as LCP) has an extremely rigid molecular structure and exhibits an effect called self-reinforcing property when oriented, and has an extremely large elastic modulus in the orientation direction. Therefore, it is preferable as the molding material of the present invention. It is also preferable in terms of excellent non-combustibility and easy provision of flame retardancy.

The advantageous characteristics of LCP are exhibited by injection molding using a mold having a rotating member. That is, the thermotropic liquid crystal resin is likely to be oriented in the resin flow direction during injection and injection. The resulting moldings have weak mechanical strength in the direction of resin flow, but conversely are strong in the direction perpendicular to the direction of flow.

If the LCP is simply injected as in the prior art without using a rotary mold, this property of the LCP becomes a disadvantage and is inconvenient. That is, conventional injection molding, that is, when molten LCP is simply injected from a gate provided at one end or side of a cylindrical cavity without using a rotating member, the LCP is oriented in the axial direction of the cylinder. Therefore, the molded product is rather weak against the stress received from the vertical direction and is not better than other resins.

However, by molding using a mold that rotates about the cylinder axis, the LCP is rotated along the wall surface of the rotating mold, and as a result, it is oriented obliquely with respect to the axial direction. Orientation is orthogonal, but usually not so much that they are orthogonal), and the molded article has increased strength against axial stress. With other resins, the change in orientation due to the rotating mold is not clear, and the strength of the molded product is the same as in simple molding.

Therefore, for the stress in the axial direction, L
Although CP may be weaker than other resins in simple injection molding, the rotating mold exerts extremely strong strength. LCP
A fibrous filler (glass fiber, carbon fiber, etc.) may be added to the above. The content of the filler can be 5 to 80% by weight based on the weight of the material composition.

It can be confirmed by various measuring methods that the constituent materials inside the hollow cylindrical body are inclined and oriented with respect to the cylinder axis direction. For example, X-ray diffraction is used for the base material resin and ultrasonic microscopy is used for the contained filler.
The orientation state can be measured and confirmed. In addition, the orientation direction can be confirmed simply by observing the flow state on the inner surface of the cylindrical body 1 as shown in FIG. 2, for example, the flow mark 2 and observing the flow direction. Depending on the colored state of the resin, it may be difficult to observe the flow state on the surface. In such a case, for example, in the case of black compounding, the orientation direction on the inner surface can be confirmed by mixing a small amount of white pellets in the resin pellets and observing the flow direction of the color.

[0033]

EXAMPLE A method of manufacturing the impact energy absorbing member of the present invention will be described. FIG. 3 shows an injection molding apparatus used in this embodiment. In FIG. 3, 11 is an injection machine, 12 is a passage (sprue) for molten polymer, 13 is a runner, 14 is a cylindrical rotary core, and 15 is an octagonal hollow. The fixed outer mold (divided mold) 16 is a forming part (cavity) of a cylindrical body formed by the rotating core 14 and the outer mold 15. 17 is the core 14
Is a bearing that holds the rotation of the rotating core, 18 is a chain that gives the rotating core 14 a circumferential motion, 19 is a motor, and 20 is a protruding pin.

Molten resin is injected from the injection machine 11 and injected into the cavity 16 from the passage 12 and the runner 13 through a gate (not shown). The rotation speed of the rotating core 14 is 100 to 400 rpm, preferably 200 to 400 r.
It is in the range of pm. The molten resin injected into the cavity rotates together with the wall surface of the rotating core 14 and is oriented at an angle with the cylinder axis direction. If the bearing 17 is made of an elastic body, there is little risk of seizure even during rotation of the core 14.

The resin used was a thermotropic liquid crystal copolyester having repeating units respectively derived from phthalic acid / isophthalic acid / 4-hydroxybenzoic acid / 4,4-dihydroxydiphenyl, the molar ratio of each monomer being Is 0.75 / 0.25 / 3/1. When the resin was observed for optical anisotropy using a polarizing microscope equipped with a hot stage, it showed optical anisotropy in a molten state at 340 ° C. or higher.

Using a composition containing 30% by weight of glass fiber (based on the total composition) in this resin, a maximum outer diameter of 30 mm, a minimum wall thickness of 1 mm and a length of 150 m were measured by the apparatus shown in FIG.
m, a weight of 15 g, a concentric cylindrical body having a hollow regular cylinder and an outer shape of a regular octagonal prism was injection-molded. The injection time was about 5 seconds and the cooling time was about 10 seconds, which required about 15 seconds in total. By observing each of the outer surface and the inner surface of the obtained cylindrical body and confirming the direction of the resin flow from the flow mark, the direction of the resin flow on the outer surface is almost the same as the axial direction of the cylindrical body. ,
The direction of resin flow on the inner surface was inclined about 33 ° with respect to the axial direction of the tubular body.

The material orientation in the hollow cylindrical body manufactured by the injection molding method using the rotating core and the fixed outer mold is such that the molten resin flow in the same direction as the axis due to the pressure applied from the injection machine and the rotation. It is determined by the balance between the axis and the molten resin flow in the 90 ° direction due to the frictional resistance between the core and the molten resin. Therefore, if there is a difference in the rotational movement of the mold members forming the inner side and the outer side of the hollow tubular body, that is, in the case of the present invention, if only the core is rotated, each portion in the wall thickness direction of the tubular body is Since the balance of both flows is continuously changing, the material orientation also continuously changes in the wall thickness direction. As a result, the orientation of each part in the wall thickness direction is different.

[0038]

Since the impact energy absorbing member of the present invention has a flat surface on the outer side surface, it can be easily attached to a shock absorber having a flat surface or a shock absorber attaching member. Further, although the shock absorbing member has a simple structure,
Stable self-destruction can be continued.

The impact energy absorbing member of the present invention produced by resin injection molding is lightweight and inexpensive to produce. Further, this impact energy absorbing member, particularly the impact energy absorbing member composed of thermotropic liquid crystal resin, has a mechanical strength against stress from the axial direction when the resin is oriented at an angle to the axial direction of the cylindrical body. Will increase.

[Brief description of drawings]

FIG. 1 is a perspective view of an impact energy absorbing member of the present invention.

FIG. 2 is a perspective view of an impact energy absorbing member of the present invention.

FIG. 3 is a manufacturing apparatus diagram for manufacturing the impact energy absorbing member of the present invention by resin injection molding.

[Explanation of symbols]

1: Impact energy absorbing member, 2: Flow mark, 1
1: Injection machine, 12: Passage of molten polymer, 13: Runner, 14: Rotating mold, 15: Fixed mold, 16: Forming part (cavity) of cylindrical body, 17: Bearing, 18: Chain, 19 : Motor, 20: protruding pin.

Claims (3)

(57) [Claims] 1. A compound mainly comprising an aromatic ring-containing compound.
As a mer and the monomer is contained in the main chain
Thermoplastic resin (hereinafter, "aromatic ring-containing thermoplastic resin")
It is called "fat". Injection molding of a thermoplastic resin composition containing
A cylindrical hollow body having a flat surface on the outer side, and the thermoplastic resin composition is opposed to the cylindrical body in the axial direction.
Impact energy characterized by tilted orientation
Absorbing member. 2. The outer shape of the tubular body is a prism.
The impact energy absorbing member described. 3. A thermoplastic resin containing an aromatic ring
The impact energy absorbing member according to claim 1 or 2, which is a pick liquid crystal polymer .