ES2637647T3 - Method for producing a gun cartridge case, and a multi-station transfer press to carry out the method - Google Patents

Abstract

A method for manufacturing a gun cartridge case having a slot, in a single multi-station deep drawing transfer press, comprising the steps of: (d2) providing a metal cup to a set of forming stations of a multi-station deep drawing transfer press, comprising a number of punches and dies, in which with said metal cup a cartridge sleeve is formed by deep drawing; and (e2) transferring said metal cup obtained in step (d2) to an additional forming station, comprising a punch and a die, in which the diameter of the base of said cartridge sleeve is reduced until the diameter of slot required; (f1) transferring said cartridge sheath having a base of reduced diameter, obtained in step (e2), to an additional forming station comprising a punch and a die to form a groove, so that the die of the stage (f1) is a split die that has a split punch to form the groove, and that can be opened after the operation; (g1) open the split die and release the cartridge case, provided with a groove, from the multi-station deep drawing transfer press, in which between the stages (d2) and g1) there are no intermediate washing stages, pickling and / or bonderization.

Description

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DESCRIPTION

Method for producing a gun cartridge case, and a multi-station transfer press to carry out the method

The present invention relates to a method for producing a gun cartridge case, having a groove, in a single deep-drawing multi-station transfer press, as defined in claim 1, and to a transfer press deep drawing of multiple stations, according to the preamble of claim 11.

Background of the invention

Normally, gun cartridge sheaths are stretched from metal sheet discs in three 'stages'. First a cup is formed from the metal sheet disc. Next, the cup is stretched to the desired length by a number of forming operations, through punches of decreasing diameters, until an adequate length of the piece is reached. A neck is then provided to the inlay, if necessary. Finally, a groove is provided to the base of the embedded and narrowed piece, to form the finished cartridge sheath.

After each annealing stage, the pieces are counted, stripped and rinsed, and they are subjected to additional quality improvement measures.

For the annealing process the piece should be cleaned, which requires a wash before annealing. After annealing, the part is pickled, bonded, and / or lubricated, which is necessary for the following drawing operations.

Depending on the caliber, the drawing process is usually carried out in a transfer press, in which the product is embedded in several sets comprising pairs of punches and dies (stations), to receive work pieces that leave a tool Deep drawing. If the drawing is carried out in a transfer press, the transport is carried out using mechanical jaws.

Normally, a transfer press comprises between 5 and 12 stations. Due to the strong reduction in the strength of the sheet, which normally from the initial resistance of approximately 3 to 4 mm to a final resistance of approximately 0.3 mm, the material hardens. Additionally, the conformability is reduced with each stage. Therefore, processes according to the state of the art require at least one additional intermediate annealing process (which includes washing and pickling), which sometimes depend even more on the caliber.

After the ironing process in the transfer press, a narrowing process exists for most rifle cartridges. The narrowing is carried out after an annealing process, to reduce the effort of the material before this essential forming process. Normally, narrowing takes place in 2 stations.

The groove and the recess are formed using special equipment, which is separated from the transfer press. To do this, the sheath is fixed in a clamp mandrel and rotated, while a tool shaped turning cuts the groove and a second tool adjusts the length.

It is easy to understand that such processes are laborious, expensive and require high investments.

Document US 3 408 718 A discloses a method for manufacturing a cartridge cartridge case in a single deep-drawing transfer press of multiple stations. The method comprises the steps of: (i) providing a metal sheet to a multi-station deep drawing transfer press, which comprises a cutting device for cutting sheets from the metal sheet, and cutting a metal layer of said metal sheet, (ii) transferring said metal layer obtained in the previous stage to a first forming station, comprising a punch and a die, in which a metal cup is formed with said metal sheet disc, (iii) transfer said metal cup to a second set of forming stations, comprising a series of punches and dies, in which with said metal cup a cartridge sleeve is formed by deep drawing and (iv) removing said cartridge sleeve from the transfer press deep drawing of multiple stations, in which between the previous stages there are no intermediate stages of washing, pickling and / or bondering.

Summary of the invention

Therefore, an object of the present invention is to provide a method for producing a gun cartridge case, which can be carried out in a single transfer press.

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This object is achieved in accordance with the invention by means of a method for manufacturing a weapon cartridge according to claim 1, and by a multi-station deep drawing transfer press according to claim 11. Preferred embodiments of the method of according to the invention are defined in the dependent claims.

Preferably, the stages of cutting raw parts from a metal sheet, and forming a cup from the metal sheet, are also carried out in the same deep drawing transfer press of multiple stations, in a sequence comprising the following stages:

(a) providing a metal sheet to a multi-station deep drawing transfer press, comprising a cutting device for cutting raw parts from the metal sheet;

(b) cutting a metal layer of said metal sheet;

(c) transferring said metal layer obtained in step (b) to a first forming station, comprising a punch and a die, in which a metal cup is formed with said metal disk sheet;

after which the cup is transferred to stage (d2), in which between stages (a) and (g1) there are no intermediate stages of washing, pickling and / or bonderization.

Preferably, the stages of cutting raw parts from a metal sheet, and forming a cup from the metal sheet, are also carried out in the same deep drawing transfer press of multiple stations, in a sequence comprising the following stages:

(a) providing a metal sheet to a multi-station deep drawing transfer press, comprising a cutting device for cutting raw parts from the metal sheet;

(b) cutting a metal layer of said metal sheet;

(c) transferring said metal layer obtained in step (b) to a first forming station, comprising a punch and a die,

in which a metal cup is formed with said metal disk sheet;

after which the cup is transferred to stage (d4), in which between stages (a) and (th) there are no intermediate stages of washing, pickling and / or bonderization.

If the cartridge case is to be equipped with a neck, as is the case in many cartridge cases for the rifle, it is desirable to produce it in the same multi-station deep drawing transfer press in which all the previous stages have been carried out. In said machine, the neck is preferably produced at the end of the process. Gun cartridge cases are normally not provided with a neck.

A forming station in the multi-station deep drawing transfer press usually comprises a pair of a punch and a die where a metal cup is formed with the metal foil, first, and subsequently an elongated shaped cartridge sleeve, with with respect to the metal cup, an extractor, an ejector and a jaw that transports the cup of the cartridge case from one conforming station to the next. In case a neck is formed, the forming station does not comprise a punch. There is only one die that forms a neck on the open side of the cartridge case, and an internal pilot to maintain the thickness of the wall.

In accordance with the present invention, a multi-station deep drawing transfer press is also provided for manufacturing cartridge cartridge sleeves in a single machine, comprising a cutting device for cutting discs from a metal sheet and a number of forming stations for embedding and forming said metal discs, according to claim 11.

Detailed description of preferred embodiments

In accordance with the present invention, the metal sheet, which is preferably a brass sheet, is supplied directly to a deep drawing transfer press. Preferably, a zigzag feeder is used to feed the material to the cutting tool that cuts discs from the metal sheet to provide a multiple cut. The zigzag feeder will use the material in the most efficient way, without unnecessary waste of material.

Next, a cup is formed in the transfer press, and the cup is transferred to subsequent stations of the transfer press, preferably without intermediate stages of washing, pickling and / or bondering. During several stages of forming, the wall thickness of the sheath is reduced to a final wall thickness.

To allow additional deep drawing and ironing operations without any annealing process of the final wall thickness, it is necessary to reduce the true deformation in each operation. Preferably, according to the process of the present invention, the number of forming stations (pairs of punches and

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dies) is larger than in known methods. Preferably, the multi-station deep drawing transfer press used in the method according to the present invention comprises between 12 and 25 total forming stations, preferably between 15 and 25. For example, to include a neck without any stage of intermediate annealing, the number of forming stations used for step (e3) will preferably be three to seven, most preferably four to five.

In step (c), the cup is preferably formed in a forming station, in which the thickness of the metal is preferably reduced between 40% and 70% while the cup is formed.

Preferably, the number of forming stations for carrying out the drawing and forming stages (d) of the cup, to form a cartridge sleeve, is three to nine, more preferably four to eight, for example five to seven. In these forming stations, the wall thickness of the cup or of the embedded sausages intermediate is preferably reduced by a higher percentage during the first stages, of the process of drawing the stage (d), than during the later stages of stage (d). For example, according to a preferred embodiment, the wall thickness of the cup is reduced between 30% and 50%, more preferably approximately 40%, in a first forming station of step (d). Although normally the reduction is between 60% and 70% approximately.

According to a further preferred embodiment, in a second station for forming stage (d) the wall thickness of the embedded sheath is reduced by a smaller percentage than in a first station for forming stage (d). Preferably, in a second forming station of step (d) the wall thickness of the embedded sheath is reduced between 20% and 30%.

According to another additional preferred embodiment, the wall thickness of the embedded sheath is reduced by a lower percentage in a third position of stage (d) than in a second station of stage (d). Preferably, in a third forming station of step (d) the wall thickness of the embedded sheath is reduced between 10% and 25%, preferably between 10% and 20%. While normally the reduction is between 25% and 35% approximately.

According to another additional preferred embodiment, in a fourth forming station of step (d), and in any other additional forming station thereof, the wall thickness of the embedded sheath is reduced by a percentage equal to or less than in a third station of conformation of stage (d). Preferably, in a fourth forming station of step (d), and in any other additional forming station thereof, the wall thickness of the embedded sheath is reduced between 10% and 20%.

With the increasing number of forming stations and, therefore, with the increase in the size of the bed, the strength of forming and cradling increases, which can lead to a flexion of the punch. Depending on the caliber of the gun cartridge case, a pressing force is preferably chosen between 75 and 250 tons, and a bed length preferably between 1000 and 3000 mm. Preferably, a corrugated mechanical press is used, or, ideally, a servo-spindle press, which can actively correct the bending of the punch.

Preferably, one or two flash holes are drilled in the embedded sleeve inside the deep drawing transfer press.

As described above, according to the state of the art, the grooving process is normally carried out in an external operation, in a turning method, in which material is removed from the blank. However, the method according to the present invention integrates for the first time the grooving steps in a transfer press, and does not remove material while the groove is formed.

The groove is formed in two stages. To form the groove, the first operation is a drawing operation in which the diameter of the base of the sheath is reduced to the required diameter of the groove. In an additional station of the deep drawing transfer press, the base of the sheath is held with a split punch, then the base and the fulminating capsule are cradled in the sheath. The material flows radially and, therefore, the groove is formed. To release the sheath from the split punch, the punch segments are opened.

This is further demonstrated with the attached Figures 1 and 2, which are a cross-sectional view of a split punch according to the present invention, in a closed state (Figure 1) and in an open state (Figure 2), respectively.

Claims (10)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 65 1. A method for manufacturing a gun cartridge case having a slot, in a single multi-station deep drawing transfer press, comprising the steps of: (d2) provide a metal cup to a set of forming stations of a multi-station deep drawing transfer press, comprising a number of punches and dies, in which with said metal cup a cartridge sleeve is formed by drawing deep and (e2) transferring said metal cup obtained in step (d2) to an additional forming station, comprising a punch and a die, in which the diameter of the base of said cartridge sleeve is reduced until the diameter of slot required; (fi) transferring said cartridge sleeve having a reduced diameter base, obtained in step (e2), to an additional forming station comprising a punch and a die to form a groove, so that the stage die (fi) is a split die that has a split punch to form the groove, and that can be opened after the operation; (gi) open the split die and release the cartridge case, provided with a groove, from the multi-station deep drawing transfer press, in which between stages (d2) and gi) there are no intermediate stages of washing, pickling and / or bonderization. 2. The method according to claim 1, comprising the steps of: (a) providing a metal sheet to a multi-station deep drawing transfer press, comprising a cutting device for trimming raw parts from the metal sheet; (b) trim a metal blank from said metal sheet; (c) transferring said metal blank obtained in step (b) to a first forming station, comprising a punch and a die, in which a metal cup is formed from said metal blank. after which the cup is transferred to stage (d2), in which between stages (a) and (g1) there are no intermediate stages of washing, pickling and / or bonderization. 3. The method for manufacturing a cartridge cartridge sleeve, having a groove and a neck, in a single deep-drawing multi-station deep transfer press according to claim 1, wherein in step (g1), After opening the split die, the cartridge case provided with a groove obtained in step (fi) is transferred to a station of additional conformation, in which a neck is provided to said elongated metal cup and, subsequently, in a stage ( th) the cartridge sleeve of the multi-station deep drawing transfer press is released, in which between stages (d2) and (th) there are no intermediate stages of washing, pickling and / or bonderization. 4. The method according to claim 3, comprising the steps of: (a) providing a metal sheet to a multi-station deep drawing transfer press, comprising a cutting device for trimming raw parts from the metal sheet; (b) trim a metal blank from said metal sheet; (c) transferring said metal blank obtained in step (b) to a first forming station, comprising a punch and a die, in which a metal cup is formed from said metal blank. after which the cup is transferred to stage (d2), in which between stages (a) and (th) there are no intermediate stages of washing, pickling and / or bonderization. 5. Method according to claim 2 or 4, wherein the metal sheet is brass. 6. The method of any of the preceding claims, wherein said multi-station deep drawing transfer press comprises between 12 and 25 pairs of punches and dies in total, preferably between 15 and 25. 7. The method of any of the preceding claims, wherein said set of forming stations for carrying out step (e2) comprises between three and five pairs of punches and dies. 8. The method of any of the preceding claims, wherein said multi-station deep drawing transfer press develops a pressing force of between 75 and 250 tons. 9. The method of any one of the preceding claims, wherein said multi-station deep drawing transfer press has a bed length between 1000 and 3000 mm. 10. The method of any of the preceding claims, wherein said multi-station deep drawing transfer press comprises a servo-spindle press, which actively corrects the bending of the punch. 5 11. Multi-station deep drawing transfer press, to manufacture cartridge sleeves for weapon in a single machine, comprising a cutting device for cutting discs from the metal sheet, and several pairs of punches and dies to stuff said metal discs, characterized in that In at least one of the punch and die pairs, the die is a split die that has a split punch 10 to form a groove.