EP1125093B1 - Production of a low-polluting jacketed bullet - Google Patents

Abstract

The process involves (i) mixing tungsten powder with a powder-formed grease or ; (ii) pressing the mixture and (iii) inserting the pre-pressed product into the bullet jacket and (vi) pressing to predetermined thickness. In the process for producing a jacketed bullet for a small caliber ammunition, the ammunition has a core comprising a tungsten containing material and a jacket lined with steel or copper.

Description

The present invention relates to a method for the production of a low-emission shell bullet the preamble of claims 1 and 2.

For centuries, inexpensive lead has been used because of its high density and soft as bullet material or at least used as core material for projectiles. The longtime Use of lead-containing projectiles in practice and Hunting ammunition has led to major toxic problems and especially the surroundings of shooting ranges Heavy metal contaminated. So it was just a matter of Time until the demand for low pollutants, in particular lead-free bullets came up. For example, in In some countries, the law already bans grist enacted for hunting across water and marshlands.

From EP -A- 0641836 it is known for the production of Masses of high density, tungsten powder in a plastic matrix to store, which in storeys and as fishing weights Find use. In doing so, these are elaborate Manufacturing process at temperatures above 185 ° C all processed into low-emission hunting ammunition.

This method has the disadvantage of being costly thermal process control and is therefore for ordnance ammunition too expensive. Furthermore, the density can be of the projectile only within narrow limits; is also the dimensional stability due to temperature fluctuations, due to the high plastic content in the core, insufficient.

WO 96/41112 contains a partial shell bullet and an ammunition body controlled dismantling described. As Core-adjustable density, lead-free heavy metals are provided, the pressed in the form of coated particles and / or are sintered. The coating of the particles should also known methods are carried out using light metals, those in a fluid bed or wobble bed, by electroplating etc. are applied. 500 µm to 1000 µm are preferred large (spherical) particles and fine powder Tungsten or tantalum and corresponding alloys. The Coating material consists of aluminum, bismuth, copper, Zinc and its alloys and composites. to targeted disassembly of the projectiles and ammunition the particle size adapted to the jacket.

The disadvantage of this invention is the complex production methods especially the metallic coating the particles, as well as the possibility not envisaged a full jacket bullet with existing lead core bullets to produce identical indoor and outdoor ballistics.

From US-A-5 789 698 is also a hollow point bullet known with a pressed core made of tungsten and lead powder, which is at the rear through a concentric disc made of a ductile material such as tin or plastic is.

This bullet is due to its high lead content and the open tip is more dangerous to the environment than conventional Lead bullets with a full jacket; the ductile disc only serves as the end of the frustoconical Tail section.

It is therefore an object of the invention to provide a method which does not have the disadvantages of the prior art can be implemented with existing operating facilities is, especially no thermal processes and / or coating processes with corresponding systems required and in the resulting density on simple Way.

The low-pollution bullet created by this process compared to an existing and previously Bullet produced in large series (ordnance ammunition 5.6 mm GP90) same weight, same outer geometry, identical indoor and outdoor ballistics and have the same penetration. In the further the dimension of the floor should also be broad Temperature range are maintained and - of course - must comply with all requirements of the Hague Convention the substitution product must also be fulfilled.

In addition, the projectile should be liquid-tight his; Manufacturing tolerances should be due to the design of the floor can be compensated.

This object is achieved by the features of claim 1 or Claim 2 solved.

This proves to be surprisingly cheap in the claims named lubricants and lubricants, as it is specified in the Weight ratios even at relatively low ones Printing to an optimal packing density in the tungsten core leads and as such no measurable intermediate layer to the Points of contact of the tungsten grains.

The projectile according to the invention can be started by a known gravimetric dosing of the tungsten powder and the lubricant and lubricant in its mass exactly and set reproducibly.

Advantageous further developments are in dependent claims described the subject of the invention.

By a tungsten powder with the specified in claim 3 Grain densities can be achieved, which are a lead core correspond.

Powdered calcium stearate has proven particularly useful, intimately mixed with tungsten powder, resulting in pressing at room temperature a one-piece body is created that holds together; alternatively enumerated in claim 4 Fabrics are also suitable.

The weight percentage specified in claim 5 is optimal, he prevents the pre-compact from breaking apart removal from the press mold and when inserting it into the Bullet jacket.

To enable the pre-compact to be manipulated properly are pressures of a little over 300 MPa advantageous, Claim 6.

The final pressing is carried out according to claim 7 with higher Printing, preferably in the range of 400 MPa.

The pressure when pressing the core material must be above 350 MPa, preferably 400 MPa.

The inclusion of a leveling and sealing compound has the advance clad steel. The core 8 consists of a Mixture of tungsten powder and calcium stearate; the compensatory and sealing compound 9 made of soft tin.

The projectile 100 is produced in a very simple manner and economical:

The shell is like the well-known ordnance ammunition usual by deep drawing a bowl from plated Steel creates. After squeezing it onto the provisional one The length of the core 8 is in the form of a pre-compact used and this is pressed with 400 MPa. After that becomes the preformed leveling and sealing compound inserted and the rear part 4 shaped and flanged. Finally, the gag groove 7 is embossed and the projectile calibrated to the finished dimension.

An automatic one takes place during the last manufacturing stages Mass balance by adding excess material the crown 6 can come out by a few 1/100 mm, without the center of mass and thus the ballistics negative to influence.

The pre-compact is made by intimately mixing 97% by weight Tungsten powder and 3% by weight calcium stearate and subsequent Molding presses generated at a pressure of 300 MPa. Both components are commercially available, with the tungsten powder one with an average grain size of 5 µm as very useful for setting a lead corresponding Has proven density.

By using notoriously known automatic weighing machines the mass of the core also in large series production reproducible to an accuracy of plus / minus 4/100 g establish.

Alternatively, the mixture of tungsten powder and the powdered Lubricants and lubricants also in the bullet jacket, exactly dosed and pressed there, with pressures of 400 at least in a last pressing MPa can be applied.

The subject of the invention has exactly the same flight dynamics Properties like the previous one to be replaced, leaded ordnance ammunition and causes them, resulting from intensive target practice environmental and Health problems not.

The manufacturing process described can basically with the previous equipment and the same staff done like conventional bullet production.

Claims (8)

1. Method for producing a jacketed projectile for small-calibre ammunition, wherein a powder containing tungsten is coated with a second component and is solidified to form a core, wherein a jacket is provided which fits this core and is composed of steel or of a copper alloy, and wherein the internal and external ballistics are predetermined, characterized in that, in a first method step, 90 to 99% by weight of tungsten powder is mixed with 1 to 10% by weight of a powdery lubricant and sliding agent, in that this mixture is pressed in a second step and the resultant initial pressed blank is inserted into the projectile jacket in the third step, where it is finally pressed to the density to be achieved, and in that, in a fourth step, a compensating and sealing compound is inserted into the rear part of the projectile and the projectile is sealed in a force-fitting manner by peening, and the entire projectile is then calibrated.
2. Method for producing a jacketed projectile for small-calibre ammunition, wherein a powder which contains tungsten is solidified in a casing composed of steel or of a copper alloy to form a core, and wherein the internal and external ballistics are predetermined, characterized in that, in a first method step, 90 to 99% by weight of tungsten powder is mixed with 1 to 10% by weight of a powdery lubricant and sliding agent, in that the projectile jacket is filled in a metered manner with this mixture in a second step, where it is finally pressed to the density to be achieved in at least one further step, and in that, in a fourth step, a compensating and sealing compound is inserted into the rear part of the projectile, and the projectile is sealed in a force-fitting manner by peening, and the entire projectile is then calibrated.
3. Method according to Claim 1 or 2, characterized in that the tungsten powder has a mean grain size of less than 10 µm, and preferably 5 µm.
4. Method according to Claim 1 or 2, characterized in that the lubricant and sliding agent is calcium stearate, magnesium stearate, aluminium stearate, sodium stearate or paraffin.
5. Method according to Claim 4, characterized in that the proportion by weight of the lubricant and sliding agent is 2 to 4 percent, and preferably 3 percent.
6. Method according to Claim 1, characterized in that the initial pressed blank is initially pressed using a pressure of at least 300 MPa.
7. Method according to Claim 6, characterized in that the initial pressed blank is finely pressed in the projectile jacket using a pressure that is higher than the initial pressing pressure.
8. Method according to Claim 2, characterized in that the core is finally pressed using a pressure of at least 350 MPa.

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