JP2005350808A - Helmet and helmet manufacturing method - Google Patents

Abstract

A flame retardant magnesium alloy containing calcium in a normal magnesium alloy has an ignition point of 200 to 300 ° C. higher than that of a normal magnesium alloy and has high mechanical strength. Thus, it has superior properties to magnesium alloys manufactured by the same method and magnesium alloys manufactured by a thixomold method in which injection molding is performed in a semi-molten state. This flame-retardant magnesium alloy is used for a helmet that is lightweight and easy to wear because there is no risk of flame in the case of a riding helmet and the yield is good in comparison with the above-mentioned magnesium alloys.
A flame retardant magnesium alloy in which calcium is added to a magnesium alloy is used. Since the flame retardant magnesium alloy to which calcium is added has a high ignition point, the risk of fire or the like is lower than other magnesium alloys even if it is used in a riding helmet or a motorcycle helmet. For drivers and sportsmen, it is possible to provide helmets that are lightweight, strong and safe, highly recyclable, less uncomfortable, and easy to wear.
[Selection] Figure 4

Description

  The present invention relates to various helmets such as riding helmets (passenger cars, motorcycles, motorbikes), baseball helmets, school helmets, work helmets worn at construction sites and work sites, and methods for manufacturing the helmets. .

  Conventionally, this type of helmet has been used as a protector that protects the head and the vicinity thereof against external impacts. Such a helmet not only protects the head and the vicinity from shocks received from the outside, but also attaches a foam cushioning material to the inside of the helmet to buffer the impact from the outside, to the head and the vicinity It has a structure that mitigates the impact. The body portion of the helmet is required to have a strength member that can withstand a shock from the outside as well as being lightweight.

  Conventionally, the body part of the helmet has been designed with emphasis on shape restrictions, weight reduction, safety, etc., AES (acrylonitrile-special rubber-styrene copolymer) resin, PC (polycarbonate) resin, polyethylene resin, phenol resin A single or a plurality of laminated thermosetting resins such as FRP is used. In addition to these thermosetting resins and FRP, metals such as titanium, aluminum and alloys thereof, mild steel and stainless steel are used for the helmet body.

  Of these, thermosetting resins and FRP helmets (plastic helmets) are said to be thick and difficult to wear, and when broken, the fractured surface becomes thorn-like, and the thorn-like fractured surface is There is a risk of causing a secondary disaster that breaks through the cushioning material and damages the damaged part of the human body, that is, the head and the vicinity.

  Also, from the viewpoint of environmental problems, thermosetting resins and FRP helmets have fatal drawbacks that cannot be recycled (recycled) from a technical and economic viewpoint. For this reason, such thermosetting resins and FRP helmets are incinerated or disposed of in landfills, but the waste may adversely affect not only the human body but also the global environment. For this reason, considering that a helmet is a mass-produced product, it is essential to use a reusable material as the material of the helmet.

  On the other hand, metal helmets such as titanium and aluminum and their alloys, mild steel and stainless steel have sufficient strength as structural members against thermosetting resins and FRP. Helmets are heavy and are not preferred because of their low shock-absorbing properties.

Therefore, a magnesium alloy helmet is proposed that is not only lighter and stronger than such metal helmets, but also has good recyclability and excellent buffering properties in consideration of environmental issues. (For example, refer to Patent Documents 1 and 2.) And the method (for example, refer patent document 3) which manufactures a helmet reinforcement by melt | dissolving the magnesium alloy which contains aluminum, manganese, zinc, etc. as a component, and die-casting, or a magnesium alloy in a semi-molten state A method of manufacturing a helmet by injection molding (for example, see Patent Document 4) is disclosed.
JP 2001-355117 A JP 2002-339139 A JP 2003-96614 A JP 2001-123316 A

  However, in the method of manufacturing a helmet using a magnesium alloy, in the die casting method such as AZ91, the melting temperature (650 to 740 ° C.) for melting and casting is close to the ignition point of the magnesium alloy (almost) Therefore, there is a problem that the risk of fire increases at the production site. Therefore, a manufacturing method for manufacturing a helmet reinforcing body by melting a magnesium alloy and die casting is industrially considered, and there is a risk of a fire or a factory explosion, and is not an effective manufacturing method.

  On the other hand, in the thixomold method in which injection molding is performed using a magnesium alloy in a semi-molten state, in the case of a thin wall like a helmet, defects such as voids are likely to occur during injection molding, so the yield is poor and mass production is Is unsuitable.

  Accordingly, the invention according to claim 1 of the present invention solves various manufacturing problems such as the production of materials such as plastics and magnesium alloys by the die casting method, and is light and strong from the driver and sportsman. It is intended to provide a helmet that is safe, easy to recycle, less uncomfortable, and easy to wear.

  In addition, the inventions described in claims 2 and 3 are intended to provide a method for manufacturing a helmet capable of suitably manufacturing the helmet described in claim 1.

  In order to achieve the above-mentioned object, the helmet according to claim 1 of the present invention is characterized in that it is composed of a flame-retardant magnesium alloy obtained by adding calcium to a magnesium alloy.

  Therefore, according to the invention of claim 1, since the flame retardant magnesium alloy to which calcium is added has a high ignition point, even if it is used in a riding helmet, a motorcycle helmet, etc., there is a risk of fire and the like other magnesium. It will be lower than the alloy.

  In the helmet manufacturing method according to claim 2 of the present invention, an alloy plate is manufactured from a flame retardant magnesium alloy in which calcium is added to a magnesium alloy, and the alloy plate is used as a raw material for heat generated by extrusion or spatula processing. It is characterized by being integrally formed into a required helmet shape by inter-molding.

  Therefore, according to the invention of claim 2, by adding calcium, a flame retardant magnesium alloy having a high ignition point is manufactured, and by integrally forming by hot forming by extrusion or spatula processing, Not only is there no risk of a factory explosion, but it can also be manufactured with improved yield.

  In the helmet manufacturing method according to claim 3 of the present invention, an alloy plate is manufactured from a flame retardant magnesium alloy in which calcium is added to a magnesium alloy, and the alloy plate is used as a raw material for heat generated by extrusion or spatula processing. It is characterized in that it is divided and formed into a partial shape of the helmet by inter-molding, and then joined to the shape of the helmet by solid phase joining consisting of fusion welding or friction stir welding.

  Therefore, according to the invention of claim 3, in the case of a helmet having a complicated shape, the helmet can be integrated by dividing it into partial shapes of the helmet and then joining the divided partial shapes together.

  According to claim 1 of the present invention described above, the flame retardant magnesium alloy to which calcium is added has a high ignition point. Therefore, even if it is used in a riding helmet or a motorcycle helmet, the risk of fire, etc. It can be made lower than the magnesium alloy. Furthermore, it is possible to provide a helmet that is light and strong for the driver or sportsman, is highly recyclable, has a little discomfort, and is easy to wear.

  According to the second aspect of the present invention described above, a helmet is manufactured by adding calcium and producing a flame retardant magnesium alloy plate having a high ignition point and integrally forming it by hot forming by extrusion or spatula processing. Can be manufactured not only without the risk of fire and factory explosion, but also with improved yield.

  According to claim 3 of the present invention described above, in the case of a helmet having a complicated shape, the helmet can be divided and formed into partial shapes of the helmet, and the divided partial shapes can be integrated by abutting and joining each other. Therefore, a helmet having a complicated shape can be easily manufactured.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
This embodiment shows a case of a helmet having a complicated shape and having a tuft portion and an ear pad portion. That is, by adding calcium to a normal magnesium alloy (for example, AZ type, AM type), the effect of raising the ignition point by about 200 ° C. compared to a normal magnesium alloy (Casting Engineering Vol. 69, No. 3, P227-P233) (1997)), an alloy plate is manufactured from a flame retardant magnesium alloy, and a pair of halved main body portions (an example of a shape portion) 1a is formed using such an alloy plate as a raw material as shown in FIG. In addition, the tuft portion (an example of the shape portion) 2 and the ear pad portion (an example of the shape portion) 3 are separately manufactured. At that time, the partial molding of the partial shapes such as the half body portion 1a, the tuft portion 2 and the ear pad portion 3 is performed by hot forming such as extrusion (pressing) or spatula processing.

  Then, as shown in FIG. 2, with the half body parts 1a butted together, solid phase bonding such as friction stir welding, or fusion welding such as laser welding, TIG welding, or MIG welding is performed as necessary. Thus, the main body portion 1 is configured by integrating the butt portion as the joint portion 4. Next, as shown in FIG. 3, the tuft portion 2 is integrated with the main body portion 1, and the butted portion is integrated as the joining portion 5 by the above-described joining method. The helmet 7 can be manufactured by integrating the butt portion as the joining portion 6 by the joining method described above.

  At that time, a flame retardant magnesium alloy obtained by adding calcium to a normal magnesium alloy has a firing point that is 200 to 300 ° C. higher than that of a normal magnesium alloy, and therefore, a manufacturing method in which melting and casting (die casting) occurs near the ignition point. Compared to, there is an advantage that it can be manufactured without causing a fire at the production site.

  And flame retardant magnesium alloy is characterized by higher mechanical properties such as higher tensile strength and elongation than magnesium alloy manufactured by melting and casting and magnesium alloy manufactured by thixomold method that is injection molded in a semi-molten state. (See Japanese Patent No. 3284232, Japanese Patent No. 3318606, and Japanese Patent No. 3030338). Furthermore, since the flame-retardant magnesium alloy is a wrought material that can be extruded or spatulated, it is a material that can be easily formed into various shapes.

  In fact, when a flame-retardant magnesium alloy with a plate thickness of 1.0 mm or 2.0 mm is used, the joint efficiency is 90% or more for friction stir welding and 88% for laser welding compared to the base metal strength. Depending on the shape and dimensions of the joint, various joining methods can be used to manufacture a helmet using a flame retardant magnesium alloy.

  In addition, the general magnesium alloy generally uses the alloy name described in ASTM (American Society for Testing & Material) standard. For example, there is an AZ-based magnesium alloy, AZ31 (A indicates aluminum but the content is 3%, Z indicates zinc and the content is 1%, and the remaining content mainly indicates magnesium), AZ61, AZ81, AZ91, etc. Is applicable. For AM-based magnesium alloys, AM20 (A is aluminum and the content is 2%, M is manganese and the content is close to 0%, and the remaining content is mostly magnesium), AM50, AM60 Etc.

  The flame-retardant magnesium alloy has been judged to be non-flammable in the material combustion test for railway vehicles conducted by the Japan Railway Vehicle Machinery Technology Association (Contract No. 103 in FY2003). For this reason, even if the flame-retardant magnesium alloy to which calcium is added is used in a riding helmet, a motorcycle helmet, or the like, the risk of fire or the like is lower than other magnesium alloys.

  In the above-described embodiment, as shown in FIG. 4, a helmet 7 having a complicated shape and having a joined main body portion 1, tuft portion 2, and ear pad portion 3 is shown. The helmet 7A may be configured by only the main body portion 1 as shown in FIG. 3, or the helmet 7B may be configured by the main body portion 1 and the tuft portion 2 as shown in FIG.

  In the above-described embodiment, the main body portion 1 is formed by integrating the butt portion as the joint portion 4 in a state where the halved main body portions 1a are butted together, but this is manufactured from a flame-retardant magnesium alloy. The main body portion may be formed by integrally forming the alloy plate into a required helmet shape by hot forming by extrusion or spatula using the alloy plate as a raw material.

FIG. 2 is a perspective view showing a state in which an embodiment of the present invention is divided and formed into a partial shape of a helmet by hot forming by extrusion processing or spatula processing. It is the figure which manufactures the main-body part in the shape of a half and integrates it by joining, (a) is a top view, (b) is a front view. It is the top view which showed the method of joining a same bunch part and a main-body part and manufacturing a helmet. It is the side view which showed the method of joining a same ear pad part and a main-body part, and manufacturing a helmet.

Explanation of symbols

1 Body part 1a Half body part (shape part)
2 Bunch (shape part)
3 Earpiece part (shape part)
4 Joining part 5 Joining part 6 Joining part 7 Helmet 7A Helmet 7B Helmet

Claims (3)

  A helmet comprising a flame-retardant magnesium alloy obtained by adding calcium to a magnesium alloy.   An alloy plate is made of a flame retardant magnesium alloy with calcium added to a magnesium alloy, and this alloy plate is used as a raw material to be integrally formed into the required helmet shape by hot forming by extrusion or spatula processing. A manufacturing method of a helmet. An alloy plate is made of a flame retardant magnesium alloy with calcium added to the magnesium alloy, and then the alloy plate is split into a helmet partial shape by hot forming by extrusion or spatula processing, and then melted. A method for manufacturing a helmet, characterized in that the helmet is joined to the shape of a helmet by solid-phase joining consisting of welding and friction stir welding.

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