The cup then has to be annealed, or heated, to relax the grain structure of the metal enough to continue elongation. The casing also has to be washed prior to being put through the next draw process. The cup has now passed through the second of three draw presses.
The cup is now much deeper than it is wide, and is starting to look like a close-ended tube. As with the first draw, the cup will need to be annealed and cleaned again prior to further elongation. The cup has now reached its total elongated length, and is now considered a casing. Notice how uneven the top of the casing is.
This is partially due to the grain structure in the side walls of the cup, as well as cup side wall thickness variations. It should be noted that it is not usual to see a casing in this form, as it would have been pinch trimmed prior to exiting the third draw press. Here we have displayed the ring of brass trimmed off the top of the tube in the last step.
The tube also has to be washed prior to being advanced onto the next step of the forming process. The forming of the primer pocket and applying the headstamp to the bottom of the casing are actually two separate steps. This step creates the primer pocket in the bottom of the casing where the primer is seated. The casing also has to be washed prior to being advanced onto the next step of the forming process.
Cartridge (firearms) - Wikipedia
Next, the pocketed and headed casing has its extraction groove cut. This operation is very similar to a horizontal lathe. The casing is clamped on a spindle and rotated at a high speed while the profile cutter is pressed against it. Prior to advancing onto the next process, the body of the casing has to be annealed again to relax the grain structure of the metal.
The casing displayed here has gone through the first taper press. As you can see, it is starting to show the profile of the neck and mouth. The casing has also begun to receive its body taper. The casing to the right has gone through the second press inside the taper operation. As you can see, the body, shoulder, and neck continue being refined to their final dimensions. Now the casing has been tapered to its final body, neck, and mouth dimensions. However, the overall casing length is still too long and does not have a flash hole yet. Prior to advancing onto the next process, the casing has to be washed again.
The casing now has to be trimmed to length. The cutter which trims the casing to its final length is unique in that when the casing has exited the cutter, the mouth of the casing has been chamfered on the inside as well as trimmed to its final length. Here we have a casing after the flash hole is punched. A high-quality casing will have a precisely punched flash hole which is free of burrs and tearing. It is also important that the flash hole is uniform in size from casing to casing. The C steel cartridge cases are, therefore, placed in an oven and heated in a carbonaceous atmosphere at a temperature in the austenite region, preferably about l,F.
This carburization of the cartridge cases causes carbon diffusion to occur, increasing the carbon content of the steel from 0. At 1,F. After the cartridge cases have been fully carburized, they are moved to a cooling chamber and cooled in an oxidationpreventive atmosphere at the most rapid rate possible without the formation of martensite. In the preferred embodiment, the carburized cartridge cases are cooled in a nitrogen-hydrogen atmosphere to a temperature of about F. The cartridge cases are then brass plated to prevent oxidation and may then be primed and loaded by any desired method.
The method of forming small articles, such as intricate stampings, from low carbon steel and subsequently carburizing the objects to increase their carbon content and, accordingly, their hardness is known. However, such a process has not heretofore been useable in the manufacture of steel cartridge cases.
- CONTACT US.
- Bonnier Corp. Website Data Disclosure?
- Ammo Is Expensive. Here’s How To Make Your Own - Task & Purpose.
- US3873375A - Method of making steel cartridge cases - Google Patents?
- Get Task & Purpose in your inbox.
- Pistol brass (straight-walled cartridges).
The teaching of the prior art is to heat the objects in a carbonaceous atmosphere and then quench and temper them to further enhance their hardness and strength. Although this process is ideal for the production of decorative steel Objects, it does not produce acceptable cartridge cases.
It has been shown herein that the steel cartridge cases are not carburized until after all forming steps have been completed so that the excessive tool wear which would occur from working high carbon steel is avoided. It is well known that when carbon steel is austenitized and then quenched, some distortion of the quenched object results from the transformation of austenite to martensite. Although this distortion may not be readily noticeable in small decorative objects, it cannot be tolerated in the manufacture of cartridge cases wherein dimensional tolerances are very small.
Additionally, cooling the steel by quenching produces a martensitic structure which inherently has a low ductility. When subjected to the pressures produced when a cartridge is fired, a steel cartridge case with such a martensitic structure would have an even greater tendency to split than a brass cartridge case. Of course, the ductility of the martensite could be increased by tempering for extended periods of time. However, such tempering would also decrease the strength of the material. The hardness of the quenched and tempered martensitic structure causes another problem in that it produces excessive wear of gun parts, such as the firing pin and extractor, and reduces the sensitivity of the rim of the cartridge case so that misfires may occur due to the resulting inability of the firing pin to apply sufficient compressive force through the case to explode the primer.
For these reasons, the carburization process, as disclosed in the prior art, has never been adaptable for the production of steel cartridge cases. Steel cartridge cases made in accordance with this invention avoid the problems heretofore encountered with steel cartridge cases. In fact, these cartridge cases exhibit physical properties very similar to those of brass cartridge cases. In the method of this invention, the carburized steel cartridge cases are furnace cooled to have a ferrite and pearlite structure.
Because of this slower cooling procedure, the distortion which occurs when austenite is quenched to produce a martensitic structure is prevented and the cartridge cases have the same dimensions after carburization as they did when they were formed. Unlike martensite, the ferrite and pearlite structure has very high ductility. Steel cartridge cases made in accordance with this invention exhibit an extremely low incidence of splitting.
During comparison firing tests of 22 caliber rim fire cartridges in twelve different rifles, no splits were recorded for steel cartridge cases made in accordance with this invention whereas splits were observed in 0. During the entire test, in which 4, cartridges, having steel cartridge cases made in accordance with this invention, were fired in both rifles and pistols, only one cartridge case showed any evidence of splitting.
In a later test, 6, such cartridges were fired in rifles and pistols without the occurrence of a single cartridge case split. Steel cartridge cases made in accordance with this invention have been found to produce only slightly more wear to firing pins and extractors than do brass cartridge cases and significantly less wear than do quenched and tempered steel cartridge cases.
The ferrite and pearlite steel cartridge cases have a hardness range of about KHN which is substantially the same as the hardness range exhibited by brass cartridge cases. Because the steel cartridge cases are heat treated during the carburization process, after the completion of all cold working, the hardness tends to be more uniform over the length of these cases than the hardness of brass cartridge cases which are used in their cold worked state.
The average tensile strength of the ferrite and pearlite steel cartridge case of this invention is about 90, psi, substantially identical to the average tensile strength of a brass cartridge case. It has been found that the tensile strength exhibited by the steel cartridge cases was generally constant in value throughout the 0. It should be apparent from the foregoing description that a new method has been disclosed for manufacturing a novel steel cartridge case structure which incorporates the advantages of brass cartridge cases without their inherent splitting tendency and at a lower cost.
A method of manufacturing a cartridge case from low carbon steel comprising the steps of forming the steel into the shape of a cartridge case, carburizing the cartridge case to increase the carbon content of the steel, and cooling the cartridge case in a gaseous medium to give the steel a ferrite and pearlite structure. The method of claim 1 wherein said cartridge case is carburized to a carbon content not substantially less than 0. The method of claim 1 wherein said cartridge case is carburized to a carbon content of approximately 0. The method of claim 1 wherein said cartridge case is carburized at a temperature of approximately 1,F.
The method of claim 4 wherein the cooling of said cartridge case is to a temperature of about F. The method of claim 7 wherein the carbon content of the steel is increased to approximately 0. A cartridge case is formed from C steel strip. United States Patent [ Bolen et a1.
Bolen, Port Penn, De1.
Swaging Rims On To Normally Un-rimmed Cartridge Cases
Chadwick, Richfield Springs, N. Gall, New Castle, Del. These and other objects and advantages of this invention can best be described with reference to the appended drawings wherein: FIG. We claim: 1.
- Consent Form | Range;
- African Encounter?
- Sonetti scelti (Italian Edition).
- DEPRESSION - DIET Facts That Help Fight DEPRESSION: A Simple Basic Book on DEPRESSION DIET FACTS.
- Cartridge (firearms).
- clean slate complex (a daynight story).
- Resizing dies.
The method of claim 1 wherein said cartridge case is cooled in a gaseous medium comprising a mixture of nitrogen and hydrogen. A method of manufacturing a cartridge case from steel strip having a carbon content of about 0. US USA en USA en. BRD0 en. CAA en.
USB2 en. CAA1 en. JPB2 en.