DE4001894A1 - Synthetic helmet - comprising textile fabric or weft layers of high-strength synthetic fibres bonded by synthetic films - Google Patents

Abstract

Synthetic helmet comprises textile, fabric or weft layers consisting of high strength synthetic fibres bonded together by synthetic films with low m.pt. at high temp. and pressure. Pref. fibres are glass fibres, synthetic carbon fibres, or ceramic fibres, esp. aramide, polyethylene or nylon fibres.

Description

The invention relates to plastic helmets made of fabrics or Knitted high-strength synthetic fibers and composite helmets an outer steel dome and an inner one Plastic helmet of the above kind.

Plastic helmets that counteract the effects of ballistic To protect particles (projectiles, fragments) hitherto manufactured by using the fabric or Knitted fabrics made of high-strength synthetic fibers by soaking them with a liquid resin and then the composite has hardened. If plastic helmets made of fabric are made, which are pre-saturated with resin, that is Tissue very rigid. Because a helmet is similar to one Is hemispherical surface, the rigid tissue must be in  Individual parts cut (approx. 6-8 individual parts per Layer) to be adapted to the shape of the helmet.

That means:

• 1. an elaborate laying work, since the individual Cuts can be placed in a mold by hand have to;
• 2. Through the cuts, the horizontal tensile forces are not optimally transmitted because of the cut there are constant interruptions. Only that Adhesive strength of the resin between the individual pieces can transfer the burden;
• 3. due to this procedure arise in the upper part of the helmet so many cuts that the helmet shell very much is greatly weakened, and the bullet resistance above the entire helmet surface is very different.

The disadvantages are noticeable firstly in that shoot through the helmet faster with a shot and secondly, that the bulge when fired at is bigger.

With this type of connection between the threads of the Fabric and the resin lose their threads Agility and so can when hitting a ballistic particle does not give way and the energy pass on to adjacent threads of the fabric, causing the Protective effect is not optimal.

A helmet made of synthetic fiber fabrics or knitted fabrics has a certain bullet / splinter resistance, is  but mechanically unstable. Because protective helmets by users are often used for purposes other than their intended purpose Bullet resistance also a certain mechanical Stability required. This stability can only be in combination with a steel outer shell. Composite helmets consisting of an outer steel calotte and an inner plastic helmet that is part of the intercepting ballistic energy, exist, are suitable for this. Helmets made in this way hold had a high impact force, but they often bulge strong one.

In the manufacture of these composite helmets pre-impregnated tissue areas in optimal partial areas cut, approx. 6-8 pieces per shift. These partial areas are warmed up, becoming softer, and in introduced a laying form. You change at the Laying between the individual part compartments and a rosette, that forms a surface in the upper part of the helmet and on the Pages are superimposed. If the helmet looks like this these individual fabric sections are folded together, it is placed in the steel dome. The steel dome is in the press and is in through the molding warmed the press. The woven fabric is then in the heated steel dome inserted and pressed. These The manual laying procedure closes the Possibility of error of incorrect positioning of the Cuts one, because helmet shells made from a combination of superimposed blanks, one certain relative position of the blanks to each other require that can change during pressing. To the another is the method described due to the high Time expenditure for manual laying economical unfavorable.  

The object of the present invention is a plastic helmet with an improved protective effect and a composite helmet made of an outer steel helmet and an inner one Plastic helmet with less deformability too create.

Another task is to develop methods for Manufacture of these helmets to provide the technical and economic disadvantages of the known Overcome procedures.

The above task can be done by a Plastic helmet made of woven or knitted fabric with higher strength Synthetic fibers, which is characterized in that the individual layers of fabric or knitted fabric with plastic films are connected to each other.

The high-strength synthetic fibers are preferably made of Plastic fibers, glass fibers, carbon fibers or Ceramic fibers. The plastic fibers are preferably made of Aramid, polyethylene or nylon constructed.

A polyethylene film is preferably used as the plastic film or an adhesive film is used.

The connection of the individual fabric or knitted fabric layers by means of suitable plastic foils causes the same The strength of the tissue when it hits a particle a group of adjacent threads of tissue Can absorb particle energy. This will be enables the mobility of the individual threads in remains to a certain extent since the free volume in the stitches are not completely made of the material of the foils is filled out. When the threads are rigidly embedded in a resin mass, which when connecting the individual  Woven or knitted layers are made with an impregnating resin a distribution of the energy over several threads (stitches) not possible.

The invention further comprises a method for Production of a plastic helmet of the type mentioned above, where you look between the fabric or knitted fabric layers introduces high-strength synthetic fibers foils and under Application of pressure and temperature creates a composite and then deep drawing the composite into the brings final form.

In a preferred embodiment, the Fabric or knitted fabric layers first coated with foils, then united into a union and finally processed by deep drawing to the plastic helmet.

The method described above enables the Metals and plastics are known from deep-drawing processes also to the composite fabric or knitted fabric with film transfer what a technical and economic Represents progress.

Another advantage of the method is that the films are free of harmful phenols, while resins usually contain phenol.

The invention includes a composite helmet from a outer steel dome and an inner plastic helmet the type according to the invention, which is characterized in that between the outer steel dome and the one Plastic composite inner plastic helmet a Interlayer from a plastic film with a lower melting point than that of the films of the Plastic composite is stored.  

The film used as the intermediate layer is preferred a polyethylene film or an adhesive film.

Finally, the invention comprises a method for Production of a composite helmet of the type mentioned above, in which one between the woven / knitted layers brings high-strength synthetic fibers foils, one as Interlayer opposite the steel dome foil with a melting point lower than that between the woven / knitted fabric layers are inserted foils, between the woven / knitted layers and the steel dome insert one using pressure and temperature Produces a composite of foils and woven / knitted layers, and finally the composite by deep drawing into the mold of the outer steel helmet.

In a special version, the steel dome is made in the preheated form of the press inserted and heated, then an adhesive film is placed in the preheated steel dome inserted. When the foil touches the steel dome the adhesive film melts somewhat and is thereby fixed. The package of fabric layers, which consists of square There are fabric cuts across the entire surface and being there are foils between the individual fabric layers laid with a machine. The package is here placed between the press, on the side with brackets fixed, and then the heated core, that is Top, shut down. The layers of fabric, which only lying loosely on top of each other are inserted into the core Pressed steel cap. Because of this, that there are no cuts, none Irregularities.

The advantages of this procedure are that the helmet is on is evenly bulletproof in all places. The  Horizontal forces can be optimally absorbed. This results in high bullet resistance and Bulge is greatly reduced. The manufacturing times from approx. 50 min. manual laying to approx. 2 min. Machine laying reduced. It can be on the between the foils laid in the fabric layers are then dispensed with if you put the film on the Laminated fabric.

Pressure and temperature influence this production the values of the helmet as follows: Low pressure and low temperature result in a higher one Bulletproof, but at the same time a larger one Bulge of the material.

A higher temperature and higher pressure result in a poor resistance to penetration, however, less bulge.

In the case of stability against bulging, the following occurs Context: As described above, the film becomes the tissue not rigidly fixed so that it is projectile can dodge. Because the high quality fabric above all Absorbs tensile forces optimally in the longitudinal direction of the fiber, this results in the optimal resistance. By the adhesive film with which the inner layers on the steel helmet are attached, the bullet is shot through the Steel dome in the border area to support the tissue used to minimize the bulge hold.  

The process is as follows: The projectile penetrates the steel shell at max. Speed roughly the size of your own outer shape. The steel surface next to the penetration hole is then completely intact and can be attached to the adhesive film Hold on layers of fabric to prevent excessive bulging to prevent.

Furthermore, a projectile hits, which is about 3 cm next to the first hits the steel cap, on a completely intact System, so that immediately next to the bullet of the first projectile the second projectile the same Resistance.

The advantages achieved with the present invention can be explained in more detail using examples explained.

example 1

To achieve a V 50 value of 620 m / sec in a ballistic test. To achieve this, a mass of 12.5 kg / m ^{2 is} required with a conventional helmet made of high-strength impregnated fabric. When using fabrics of the same fibers glued with foils, a 10% lower mass is necessary. If the masses of the helmets are kept the same, the V 50 value increases accordingly. In the aforementioned example, the woven / knitted fabric consisted of high-strength polyethylene fibers and the film made of polyethylene.

Example 2

A composite helmet with a traditional steel calotte comes with a sliver (1.1 g) with a Impact speed of 620 m / sec. shelled, being the helmet bulges 30-35 mm. A helmet that type according to the invention, in which a polyethylene adhesive film between the steel helmet used as a deep-drawing mold and the first fabric layer of a composite of woven / knitted fabrics and Polyethylene film was introduced resulted in a Significant reduction in dent depths (15-20 mm).

With the help of the present invention Plastic helmets and composite helmets from a steel helmet and an inner plastic helmet created that respect their protective effect and mechanical resistance are significantly improved. Furthermore, a method for Manufacture of these helmets are developed against that the state of the art clear technical and has economic advantages.

Claims (9)

1. Plastic helmet made of woven or knitted high-strength synthetic fibers, characterized in that the individual layers of fabric or knitted fabric are connected to one another by plastic films. 2. Plastic helmet according to claim 1, characterized characterized that the synthetic fibers made of plastic fibers, glass fibers, carbon fibers or Ceramic fibers exist. 3. Plastic helmet according to claim 2, characterized characterized in that the plastic fibers are made of aramid, polyethylene or nylon. 4. Plastic helmet according to claim 1, 2 or 3, characterized characterized that the plastic film Is polyethylene. 5. Method of making a plastic helmet according to one or more of the preceding Claims, characterized, that one between the woven / knitted layers foils brings in, using pressure and temperature creates a composite and the composite by deep drawing into the final form. 6. The method according to claim 5, characterized characterized that the Woven / knitted layers are coated with the foils.   7. Composite helmet consisting of an outer steel dome and one inner plastic helmet according to claim 1, characterized characterized in that between the outer steel dome and the one Plastic composite inner plastic helmet with an intermediate layer made of a plastic film a melting point lower than that of the films of the Plastic composite is stored. 8. composite helmet according to claim 7, characterized characterized that the Intermediate layer of a polyethylene film or adhesive film is. 9. Method of manufacturing a composite helmet according to Claim 7 or 8, thereby characterized in that between the Woven / knitted layers made of high-strength synthetic fiber films introduces one as an intermediate layer opposite the Steel dome serving foil with a melting point, the lower than that between the Woven / knitted fabric layers, between the woven / knitted layers and the steel dome inserted, using pressure and temperature a composite of the foils and the knitted / woven layers manufactures and the composite by deep drawing into the mold the outer steel calotte brings.