JP3462406B2 - Impact energy absorbing member having screw portion - 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 bumper support member) for absorbing the impact 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 bridge pier, an aircraft, a helicopter or an elevator fails. As a shock absorber to absorb the impact when landing on the ground, or as a shock absorber to absorb the impact when a nuclear fuel transportation device (cask) or a container (canister) containing radioactive waste falls. The transport means is equipped with an impact energy absorbing member that absorbs impact energy irreversibly.

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, these shock absorbing structural members are excellent in the characteristics as the shock absorbing structural member itself, but (1) the structure is complicated and prone to failure (mechanical, corrosion, etc.) (2) high manufacturing cost (Advanced processing, high energy consumption manufacturing process, etc.) (3) There are problems such as heavy (use of metal materials), and improvement in these points is desired.

In recent years, with respect to the shock absorbing structural members mounted on vehicles, aircrafts, elevators, etc., there has been an increasing demand for space saving and weight saving in accordance with the trend toward weight reduction and higher functionality 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.

[0006] Further, these transporters have a strong tendency to reduce costs, and from this point of view, studies are being made from both aspects of material and structure.

[0007] With these studies, the above-mentioned drawbacks of the conventional impact energy absorbing member have come to be recognized as an extremely serious problem than ever before.

In order to overcome this problem, the development of impact energy absorbing members made of fiber composite synthetic resin has come to be carried out, especially focusing 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 structure 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 structure 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 function effectively, it is important to devise so that a sudden load is not generated particularly during collision deformation. For example, the cylinder does not buckle during the fracture, and continuous and stable fracture continues until the final stage, whereby large energy absorption is achieved.

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 is continued. here,
So to speak, the change in wall thickness in the axial direction is the 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.

[0013]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, it is an object of the present invention to employ a simpler structure in a cylindrical impact absorbing energy member to continue stable destruction.

[0014]

The above-mentioned object is to perform injection molding.
The above-mentioned impact energy absorbing member is obtained by attaching a lid and / or a semi-spherical bottom to a hollow cylindrical main body in which the thermoplastic resin composition is inclined and oriented in the axial direction .

That is, the first impact energy of the present invention
The absorbent member is mainly composed of a compound containing an aromatic ring.
And the monomer is contained in the main chain
Thermoplastic resin (hereinafter "aromatic ring-containing thermoplastic resin")
Injection molding of a thermoplastic resin composition containing
The thermoplastic resin set constituting the inside and / or the outside
Hollow cylindrical shape in which the product is inclined with respect to the cylinder axis direction
The body is the main body, the top of which is screwed into the lid and / or
A portion whose bottom bulges in a semicircular shape outward in the axial direction of the cylindrical body.
It is characterized by being blocked with a material.

The second impact energy absorbing member of the present invention
The absorbent member according to claim 1, wherein the lid is the
It has a portion having a diameter larger than the inner shape of the hollow cylindrical body.

The third impact energy absorbing member of the present invention
Is an aromatic ring-containing compound in the absorbent member according to claim 1 or 2.
The thermoplastic resin is a thermotropic liquid crystal polymer
It

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The impact energy absorbing member of the present invention is usually made of resin, and is used in a state in which it is attached so that an impact is applied from the vertical direction of the cylindrical portion, that is, the axial direction.

1 and 2 are respectively a front view and an exploded perspective view of an embodiment of the impact energy absorbing member of the present invention. In the drawings, reference numeral 1 is an impact energy absorbing member of the present invention, and the hollow cylindrical body 2 which is the main body thereof has a bottom closed by a semi-spherical bottom member 3, and usually the cylindrical body 2 and the bottom portion. The material 3 is integrally molded. A female screw 5 is cut at the top of the hollow cylindrical body 2, and a lid 4 having a male screw 6 partially cut therein is screwed into the female screw 5. By screwing, the relative positions of the cylindrical body and the lid are fixed.

When an impact is applied to the impact energy absorbing member of the present invention from above, the lid screwed into the hollow cylindrical body serves as a trigger for breaking the cylindrical body. In particular, as shown in FIG. 3, when the lid 4 has a portion (head) 8 having a diameter larger than the inner diameter of the cylindrical body 2, that portion mainly serves as a trigger. That is, when an impact force is applied to the top surface of such a lid, the screwed portion is broken and begins to sink into the hollow portion of the cylindrical body 2, and eventually the head 8 having a large diameter contacts the top portion of the cylindrical body 2. Then, the cylindrical body 2 starts to spread outward in the radial direction, and the destruction of the cylindrical body 2 progresses.

In order for the lid 4 to act as a trigger when the cylindrical body 2 is broken, the relative positions of the lid 4 and the cylindrical body 2 need to be fixed. That is, when an impact force is applied to the top surface of the lid 4, the lid 4 descends in parallel to the axial direction of the cylindrical body 2 to exert a trigger function.
Since the impact force causes the cylindrical body 2 to be destroyed, it is not a weak stress. Therefore, the impact force may cause displacement of the relative position or the like, but such a situation hinders the normal function of the trigger. Therefore, the relative positions of the lid and the cylindrical body need to be accurately fixed. In the present invention, since the lid 4 is screwed into the cylindrical body 2 as described above, the relative positions thereof are accurately fixed, and as a result, the lid 4 serving as a trigger is fixed.
Can fully demonstrate its trigger function.

The bottom portion 3 of the hollow cylindrical body 2 is closed, and as shown in FIG. 1, the shape of the bottom portion 3 bulges outward in the axial direction of the cylindrical body 2, that is, in a downward semispherical shape. The hemispherical (curved) portion that bulges downward can be said to be a destruction trigger in that it exerts a function of guiding the hollow cylindrical body 2 to be destroyed in a preferable destruction mode (see FIG. 4). In order to absorb the impact energy to the maximum, a fracture type in which the cylindrical wall gradually spreads from one or both of the upper and lower ends toward the center is preferable. In the middle of the cylinder, the fracture type that bends or buckles suddenly is the worst case where the absorption rate of impact energy is the lowest.

As shown in FIG. 4, when the impact energy absorbing member of the present invention receives an impact force from the curved bottom surface 3 in a direction parallel to the cylinder axis, the direction of the stress causes the curved portion 3 to move the cylinder from the cylinder axis direction. It changes to the direction of unfolding. As a result, fracture of the cylinder 2 begins so as to push the cylinder wall outward. This is also a destruction trigger.

The impact energy absorbing member of the present invention has a bad seating because the bottom plate is curved, but when it is applied to a shock absorber, it is not simply placed on a flat plate but is fixed to the device by an appropriate mounting bracket. (With a top and bottom sandwiched between flat plates),
Even if there is some curvature on the bottom, there is no inconvenience for installation. A cross-shaped groove may be provided on the bottom or the surface of the lid that contacts the flat plate.

When the hollow cylindrical body is composed of a thermotropic liquid crystal resin, it is preferable that the resin is oriented in a direction different from the axial direction of the cylindrical body on at least one of the inner side and the outer side of the cylindrical body. That is, the more the orientation direction of the thermotropic liquid crystal resin is inclined with respect to the axial direction of the cylindrical body, and the closer to the radial direction the mechanical strength of the cylindrical body against the stress from the axial direction is increased.

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 has a screw thread, so that it is manufactured by injection molding. Since it is injection molding, any thermoplastic resin can be used as the material resin. Here, the male thread cap can be molded separately from the cylindrical body by a conventionally known injection molding method. The threaded lid can be molded by injecting resin into a mold having a threaded cavity. Of course, it is also possible to once form a lid without threads and form threads on it by cutting or the like. A cylindrical body having an internal thread or a cylindrical body having an internal thread and a curved bottom portion can also be manufactured by a usual injection molding method.

If the orientation of the resin is utilized by injection-molding a cylindrical body using a rotary mold member as described below, a thermoplastic resin having a property of exhibiting a high elastic modulus by the orientation is used. preferable.

A typical thermoplastic resin that exhibits 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 properties of LCP are:
It is 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 conventional case without using a rotary mold, this property of the LCP becomes a disadvantage and is inconvenient. That is, when conventional molten LCP is simply injected from a gate provided at one end or side surface of a cylindrical cavity without using a rotating member, the LCP is oriented in the axial direction of the cylinder. Molded products are weaker than the stress received from the vertical direction and are not as good as other resins.

However, by molding using a mold that rotates about the cylindrical 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. For other resins, the change in orientation due to the rotating mold is not clear,
The strength of the molded product is the same as that of simple molding.

Therefore, for stress from the axial direction,
Although LCP may be weaker than other resins by simple injection molding, the rotary mold exerts extremely strong strength. LC
A fibrous filler (glass fiber, carbon fiber, etc.) may be added to P.

On the other hand, since the lid is molded by ordinary injection as described above, the material is not particularly limited as long as it is a high-strength resin.

Next, a preferred method for manufacturing the impact energy absorbing member of the present invention will be described. The hollow cylindrical body is molded by injection molding of a thermoplastic resin using a mold including a rotating member, and the rotating member may be either an inner core or an outer mold. When the outer mold is rotated, a cylindrical body in which the resin on the outside is obliquely oriented with respect to the cylindrical axis is obtained as shown in FIGS. It is economical to integrally mold the curved bottom portion with the cylindrical body. The obtained cylindrical body has a female screw structure at the top and a closed bottom as shown in FIGS. The lid with the male screw is injection molded separately. Finally, the lid is screwed onto the cylindrical body to complete the impact energy absorbing member of the present invention.

The constituent material inside and / or outside the hollow cylinder has an inclined orientation with respect to the axial direction of the cylinder.
It can be confirmed by various measuring methods. For example,
The orientation state can be measured and confirmed by X-ray diffraction for the base material resin and by an ultrasonic microscope for the contained filler. In addition, for simplicity, the cylindrical body 2 as shown in FIG.
The orientation direction can be confirmed by observing the flow state on the surface, for example, the flow mark 7, and observing the flow direction of each surface. 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 blending, the orientation direction on each surface can be confirmed by mixing a small amount of a white pellet in a resin pellet and observing the flow direction of the color.

[0037]

EXAMPLE A method of manufacturing the impact energy absorbing member of the present invention will be described. FIG. 5 shows an injection molding apparatus used in this embodiment. In FIG. 5, 11 is an injection machine, 12 is a molten polymer passage (sprue), 13 is a runner, 14 is a rotating core, 15 is a fixed outer mold, 16 Is the rotating core 14 and the outer mold 1
5 is a forming portion (cavity) of the cylindrical body formed by 5. 18 is a chain that gives the rotating core 14 a circumferential motion,
Reference numeral 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 cylindrical axis direction.

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 entire composition) in this resin, the apparatus of FIG. 5 has an outer diameter of 20 mm, a wall thickness of 1 mm, a length of 150 mm, and a weight of 15 g. A hollow cylindrical body with a female thread having a curved bottom 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 resin flow from the flow mark, the direction of resin flow on the outer surface was almost the same as the axial direction of the cylindrical body. , The direction of resin flow on the inner surface is about 33 with respect to the axial direction of the cylindrical body.
° It was tilting.

On the other hand, using the same thermotropic liquid crystal copolyester as described above, the diameter of the head portion is 20 mm, the screw portion is 19 mm, and the length (height) is 1 by injection molding by a conventional method.
A 0 mm male threaded lid was molded. Finally, the lid was screwed onto the cylindrical body to complete the impact energy absorbing member of the present invention.

A compressive load was applied to the obtained absorbent member in the axial direction, and the relationship between the compressive load and the amount of displacement was measured. Results are shown in FIG. As is clear from the figure, the energy absorbing member of the present invention is in a stable state with a substantially constant load generated as the displacement amount increases. As a result, the absorbed energy represented by the area between the load curve and the axis representing the amount of displacement is also large.

The material orientation in the hollow cylindrical body manufactured by the injection molding method in which the rotating core, the outer mold, or both are rotated is such that the molten resin in the same direction as the axis due to the pressure applied from the injection molding machine. It is determined by the balance between the flow and the molten resin flow in the 90 ° direction with respect to the axis due to the frictional resistance between the rotating member and the molten resin. Therefore, if there is a difference in the rotational movement of the members that form the inside and the outside of the hollow cylindrical body of the mold (for example, when only the inner forming member is rotated), each portion in the wall thickness direction of the cylindrical 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.

[0044]

The impact energy absorbing member of the present invention is excellent in impact absorption in the axial direction of the cylinder because the lid screwed into the hollow cylindrical body functions as a breaking trigger. Also,
The curved bottom also acts as an auxiliary trigger, providing the preferred mode of failure in which the cylindrical wall gradually spreads outwards from the end to the center. As a result, the energy absorbing member of the present invention has a simple structure, but a substantially constant load is generated as the amount of displacement increases, and the fracture proceeds stably. Therefore, the absorbed energy of the absorbing member, which is represented by the area between the load curve and the axis representing the amount of displacement, is also large.

The impact energy absorbing member of the present invention manufactured by resin injection molding is lightweight and inexpensive to manufacture. 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 front view of an impact energy absorbing member of the present invention.

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

FIG. 3 is a conceptual diagram of a screw fitting trigger.

FIG. 4 is a conceptual diagram of a curved bottom trigger.

FIG. 5 is a manufacturing device diagram for manufacturing the impact energy absorbing member of the present invention by injection molding of resin.

FIG. 6 is a graph showing a relationship between a compression load and a displacement amount when an axial load is applied to the energy absorbing member of the present invention.

[Explanation of symbols]

1: Impact energy absorbing member, 2: Hollow cylinder, 3: Bottom part, 4: Lid, 5: Female screw, 6: Male screw, 7: Flow mark, 8: Head of lid, 11: Injection machine, 12: Molten polymer passage, 13: runner, 14: rotating part, 15: fixed mold, 16: forming part (cavity) of cylindrical body, 18:
Chain, 19: motor, 20: protruding pin.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Mori 811-1 Kanada, Nagakata, Fukuoka Prefecture, Meiho Co., Ltd. (72) Inventor Hiroyuki Miya, 811-1, Kanada, Nakata, Fukuoka Prefecture, Meiho Co., Ltd. (56) References JP-A-8-170675 (JP, A) JP-A-9-60676 (JP, A) JP-A-6-300067 (JP, A) JP-A-3-37426 (JP, A) Actual flat 2 -42868 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16F 7/12

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")
Injection molding of a thermoplastic resin composition containing
Said thermoplastic tree constituting the inner and / or outer
The main body is a hollow cylindrical body in which the fat composition is inclined and oriented with respect to the cylinder axis direction , and the top of the hollow body is screwed into the lid and /
Alternatively, the impact energy absorbing member is characterized in that the bottom is closed by a member that bulges in a semicircular shape on the axially outer side of the cylindrical body. 2. The impact energy absorbing member according to claim 1, wherein the lid has a portion having a diameter larger than the inner shape of the hollow cylindrical body. 3. A thermoplastic resin containing an aromatic ring is a thermo
2. A ropic liquid crystal polymer.
Or the impact energy absorbing member according to 2.