KR20130038363A - Contoured thickness blank for ammunition cartridges - Google Patents

Abstract

The austenitic stainless steel ammunition cartridge 12 comprises an outer region 16 and a base, the outer region 16 being about 50% to 80% of the thickness of the base, which is the sidewall ironing required to form the cartridge. Minimize the function. The cartridge blank 10 may be formed by spin molding, compression molding, grinding or a combination thereof. The tooling 76 for forming the blank 10 may comprise at least a pair of blocks 80 and inserts 78, the at least one insert forming a centrally located hole 82.

Description

Contoured thick blanks for ammunition cartridges {CONTOURED THICKNESS BLANK FOR AMMUNITION CARTRIDGES}

preference

This application is directed to US Provisional Patent Application, filed Jul. 14, 2010, entitled "CONTOURED THICKNESS BLANK FOR AMMUNITION CARTRIDGES," the disclosure of which is incorporated herein by reference. 61 / 364,263 claims priority.

Ammunition includes a metal case or cartridge, typically made of brass, that packages bullets, gunpowders, and primers, respectively. The filled cartridge is shaped to fit correctly in the firing chamber of the firearm.

The manufacture of such brass cartridges is generally known to include annealing cups of heavy gauge brass and deep drawing the cups through a multi-stage press apparatus into the final shape of the cartridge. The process for brass further includes a re-drawing process for tapering the wall against the base and ironing of the cartridge sidewalls during drawing, with a number of intermediate annealing being a deep drawing process. Is performed in between.

Brasses with sufficiently low work hardening rates and low frictional forces can be used with multiple annealing and sidewall ironing processes and are suitable for such deep drawing processes that include heavy sidewall ironing. Steel, on the other hand, has such properties as high work hardening rate, high strength and high frictional force. These characteristics can lead to galling and scoring problems, which typically result in reduced die life and are difficult and generally not viable for heavy sidewall ironing during repeated redrawing and annealing steps. do. In addition, although carbon steel is used to form cartridges, such cartridges include the application of waxing or protective coatings to prevent rust.

The specification has resulted in a claim that specifically teaches and expressly claims the invention, but the invention may be better understood from the following description of specific examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements. will be.

1 is a cross-sectional view of an ammunition cartridge blank according to an example of the invention in a first state;
FIG. 2 is a sectional view of the cartridge cartridge blank of FIG. 1 in a second molded cartridge state; FIG.
3 is an elevation view of an exemplary spin forming operation.
4 is an elevation view of another exemplary spin forming operation.
5 is an elevation view of an exemplary compression molding operation.
6 is an elevation view of a die for an alternative exemplary compression molding operation.
7 is an elevation view of an exemplary grinding operation.
8 is an elevation view of another exemplary spin forming operation.
9 is an elevation view of an exemplary plunger and a cylindrical cartridge formed via a plunger.
10 is an exploded perspective view of exemplary tooling.

The drawings are not intended to be limited in any way, and it is contemplated that various embodiments of the invention may be performed in a variety of other ways, including those not necessarily shown in the drawings. The accompanying drawings, which are incorporated in and form a part of the specification, illustrate many aspects of the invention and, together with the description, serve to explain the principles of the invention, but the invention is not limited to the precise arrangements shown. I understand.

The following description of specific examples of the invention should not be used to limit the scope of the invention. Other examples, features, aspects, embodiments and advantages of the invention will be apparent to those skilled in the art from the following description. As can be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

Blank

1 shows an exemplary cartridge blank 10 in a first state, and FIG. 2 is shown in a second state, for example as a cartridge 12 drawn in a cylindrical shape after a first drawing operation. An exemplary contoured thick blank 10 formed in the first state as shown further below is shown in FIG. 1 as having a center button 14 and an outer region 16. The thicker center button 14 becomes the base of the cylindrical cartridge in the second state. The outer region 16 is reduced to at least 50% of the thickness of the button 14 to allow minimization of sidewall ironing when the cartridge 12 is drawn in a cylindrical shape. As shown in FIG. 2 and as described below, the button 10 of FIG. 1 is further processed to form the cartridge 12 of FIG. 2 such that the button 14 has a base of the cylindrical cartridge 12 ( 18).

The blank 10 may be formed of a metal including, but not limited to, austenitic stainless steel. Austenitic stainless steels are known to those skilled in the art. It is an alloy comprising chromium and nickel having austenite as the primary phase. This alloy exhibits high ductility, low yield stress and high tensile strength when compared to other steels. The austenitic stainless steel composition can be, for example, by weight percent of up to 0.045% C, up to 0.60% Si, from about 0.03% to 0.06% N ₂ , from about 1.0% to about 1.4% Mn, from about 17.2% to about 17.8 % Cr, about 3.1% to about 3.4% Cu, about 8.1% to about 8.4% Ni, up to 0.035% P, up to 0.002% S and up to 0.4% Mo. Alternatively, the austenitic stainless steel composition may be, for example, in weight percent of approximately 0.035% C, 0.45% Si, 0.045% N ₂ , 1.2% Mn, 17.5% Cr, 3.25% Cu, 8.25% Of Ni, low weight percent of P and S, respectively, and Mo of 0.2%. The above-mentioned composition is shown in Table 1 below, where M = maximum amount.

Austenite Of stainless steel  Chemical composition (measured in weight percent) C Si N ₂ Mn Cr Cu Ni P S Mo range 0.045M 0.60M .03 /
.06 1.0 /
1.4 17.2 /
17.8 3.1 /
3.4 8.1 /
8.4 .035M .002M 0.4M goal 0.035 0.45 0.045 1.2 17.5 3.25 8.25 that that 0.2

Under cold rolled and annealed conditions, these austenitic stainless steels have 0.2% yield strength = 31.5 ksi (217.2 MPa), maximum tensile strength (UTS) = 77.5 ksi (534.3 MPa), total elongation at break (2 "original gauge) Based on length) = 52.5% and n-value (10% for Ult) = 0.404 and 68 HRBW, including mechanical properties, such properties performed according to ASTM E 8 and A 370. The n-value or work hardening index can be obtained simultaneously, but the determination method is covered under ASTM E646. The materials tested in the examples described below and the austenitic stainless steels described above are examples. For example, melted, hot rolled from about 2250 ° F. (1232.2 ° C.) to about 2320 ° F. (1271.1 ° C.), strip annealed from about 1950 ° F. (1065.6 ° C.) to about 2000 ° F. (1093.3 ° C.), cold rolled, and finally Can be annealed at about 1950 ° F. (1065.6 ° C.). .

The blank can be prepared by any method known in the art. 3 to 7 show a method for preparing the blank 10 in its first state. In their first state, the blank comprises an outer area 16 surrounding the button 14 such that the outer area 16 has a thickness in the range of between about 50% and 80% of the thickness of the center button 14. can do. For example, as shown in FIG. 2, sidewall 20 may range from about 0.015 (0.381 mm) to 0.025 inch (0.635 mm), and base 18 may have a thickness greater than the sidewall thickness. This larger comparison thickness requires minimal ironing during the forming process to position the outer region 16 from the first state of FIG. 1 to the second state of FIG. 2 where the outer region 16 forms the sidewall 20. Shall be. In another example, the blank may include an outer region 16 surrounding the button 14 such that the outer region 16 has a thickness in the range of between about 50% and 60% of the thickness of the center button 14. .

The blank may be spin formed as shown in FIG. 3 or 4. Referring to FIG. 3, the arm 22 of the rolling mill may comprise a shaft 24 and a head 26 and may rotate about each longitudinal axis A of the shaft 24. Each head 26 is generally trapezoidal in shape, but other shapes may be apparent to those skilled in the art. The head 26 is a third and third disposed between them at each end of the first generally horizontal blank contact surface 28, the opposing second surface 30 and the first and second surfaces 28, 30. Four surfaces 32, 34. The third and fourth surfaces 32, 34 are generally parallel to each other and the axis A is substantially perpendicular to the third and fourth surfaces 32, 34.

The blank 10 includes a mechanical contact surface 36 and an opposing bottom 38. Surfaces 36 and 38 are arranged generally parallel to each other. The blank 10 comprises a central axis B which is substantially perpendicular to the head contact surface 36. One or more of the rolling mills such that the blank contact surface 28 of the head 26 of the rotating arm 22 operates against the mechanical contact surface 36 of the blank 10 to form the button 14 and the outer region 16. The blank 10 rotates around the central axis B while the arm 22 rotates around each longitudinal axis A, and the button 14 has a thickness greater than the outer area 16. Alternatively, the arm 22 may rotate while the blank 10 remains stationary.

Alternatively, as shown in FIG. 4, the rolling mill has a shaft 42 with a longitudinal axis C and a circumference around the longitudinal axis C of the shaft 42, for example as shown in the direction of the arrow D. FIG. It may include an annular arm 44 rotatable. The blank 10 is in this example version when a portion of the rotating arm 44 acts on the mechanical contact surface 36 of the blank 10 while the blank 10 rotates about the central axis B. It is formed to include the button 14 and the outer area 16 as described above. Alternatively, the arm 44 may rotate while the blank 10 remains stationary.

The blank may be compression molded by cold forming, warm forming, hot forming or forging under linear compression load. As shown in FIG. 5, the blank 10 may be disposed on the upper surface 46 of the lower block 48 of the press 50. The upper block 52 of the press 50 can include a first portion 54, a second portion 56 and a third portion 58, the second portion 56 being the first and third portions. It is arrange | positioned between 54 and 58. The first and third portions 54, 58 may be substantially rectangular or square in shape, although other shapes are within the scope of the present invention. The first and third portions 54, 58 may have a substantially linear base for compressing against the blank 10 to form the outer region 16 when driven in the direction of the arrow E. The second portion 56 includes walls 60, 62, 64 that form holes 66 that are dimensioned and configured to compress against the blank 10 to form the button 14. The two halves of the press are combined together in a manner known in the art to form the blank 10.

The process may also involve using a three-die compression tooling design. The first and second dies may look similar to that shown in FIG. 5, except that the lower surface of the upper press may be angled relative to the upper surface of the lower press as shown in FIG. 6. For example, FIG. 5 shows a flat parallel surface between the upper press and the lower press. 6 shows a die having a non-parallel surface between the upper press and the lower press. The first die may include a flat top surface 124 for the lower press 126, for example, as shown in phantom in FIG. 6. The first die may additionally include an angled bottom surface 128 for the top press 130 angled with respect to the flat top surface 124 of the bottom press 126 at an angle N. The angle N may be 1 degree, for example, so that when the two presses are in compression, the outer end of the angled lower surface of the upper press is removed about 0.018 "(0.46 mm) from the upper surface of the lower press. Alternatively, the angle N may range from about 0.1 degrees to about 5. The slope added to the two rigid forming stages via the first and second dies is for example at the top surface of the lower press. The above described angulation of the lower surface of the upper press with respect to the flow of the blank material outward as the material can be moved more gradually and forced outward.

Alternatively, an exemplary grinding operation as shown in FIG. 7 can be used to form the blank 10. The blank 10 may be aspirated or vacuumed to lower the block 68 by the downward force (F). As shown in FIG. 7, the arm 70 includes a central hole 72 through which the shaft 74 extends. The shaft 74 comprises a substantially horizontal longitudinal axis G around which the shaft 74 rotates in the direction of the arrow H. This rotation, for example via a gear mechanism (not shown) engaged with each other, will effect the up and down vertical movement as shown by arrow I in a direction substantially perpendicular to the longitudinal axis G of the shaft 74. Can be. Alternatively, the shaft 74 can move non-rotationally in a direction substantially perpendicular to the axis G to effect similar movement of the arm 70. The arm 70 is in a position for grinding against the blank 10 to produce the outer region 16 as the blank 10 rotates about the central axis B, for example in the direction of the arrow J. FIG. Is moved. Additionally and / or alternatively, arm 70 may execute a downward stroke while grinding against blank 10, which may or may not be rotatable.

Alternatively, as shown in FIG. 8, the blank may be formed directly into the cylindrical cartridge via a spin forming operation. For example, a flat blank, such as a blank 100 that is approximately 0.06 "(1.524 mm) thick, may be spin formed on the lower support 102 in a cylindrical shape. The spinning machine 104 together shaft and arm assembly It may include a shaft 106 and an arm 108 extending from the shaft 106, forming a 110. The shaft and arm assembly 110 is around the longitudinal axis K of the shaft and arm assembly 110. And the blank 100 may be stationary as shown in Fig. 7, or may rotate simultaneously about the longitudinal axis of the blank 100. The shaft and arm assembly 110 is shown in Fig. 7 It may move downwards in the direction of arrow L to form sidewall 112 of cylindrical cartridge 114 shown in phantom in. For example, outer region 116 of blank 110 may have sidewall ( Can be formed downward in the direction of the arrow (M) to form 112 have.

Alternatively, as shown in FIG. 9, the contoured plunger 118 having an upper width less than the lower width allows for a thickness variation along the length 120 of the cylindrical cartridge 122 required in the final cartridge shape. Can be used. The process may be performed in a single operation that does not require additional intermediate steps to produce a cylindrical shape, which may, for example, rule out three to four intermediate annealing steps. In addition, the three initial drawing operations required in other cases to form a cylindrical shape from a simple contoured flat blank can be ruled out as described below. Optionally, the center button may be brazed into a round flat of about 0.020 "(0.508 mm) to about 0.04" (1.016 mm) thick.

Alternatively, tooling 76 to form the blank may be used. This tooling includes insert 78 and block 80 as shown in FIG. Insert 78 may be made of, for example, D-2 tool steel, has a center plate that is 2 "(50.8 mm) diameter, 3/8" (9.525 mm) thick, and may have a hardness of 61 HRC. Block 80 may be made of, for example, O-6 tool steel, and may have a hardness of 59 HRC. At least one of the inserts 78 may include a central hole 82 extending therethrough. The central hole 82 may be, for example, 0.5 "in diameter. The block 80 may include a guide pin 84 configured for receipt in the blind bore 86 of the block 01, but the guide pin ( 84 may be configured for receipt in a hole formed in and extending through block 80.

Alternative exemplary toolings are manufactured by CARPENTER TECHNOLOGY CORPORATION, Meridian Boulevard, 19610-1339 Meridian Boulevard, Pa., 5% chrome hot working tool steel available for applications requiring extreme toughness. Carpenter 883 (type H15) tool steel. For example, type H15 tool steels are known to have the ability to be used for hot forming and / or forging. With this steel tool, molding can be performed at room temperature under static load. Options include tooling for attempts to heat the die and material. However, type H15 tools perform well for cold forming because the tooling resists cracking and distortion on the loading surface (ie the surface remains flat and parallel).

Any shape for such tooling may be used as may be apparent to those skilled in the art in light of the teachings herein. For example, such tooling can include cylindrical blocks dimensioned to produce suitably dimensioned blanks. Alternative exemplary tooling may include S-7, an air hardened grade tool steel having 0.55% carbon, 3.25% chromium and 1.4% molybdenum. Any tool steel may be used as may be apparent to those skilled in the art in light of the teachings herein based on factors such as cost and desired manufacturing life.

The tooling described above may be heat treated. Exemplary methods of heat treating tooling, such as the type H15 tooling described above, include sealing the tool or tooling in a stainless steel bag. The bag minimizes surface oxidation of the tooling during the annealing process. The tooling must be protected from oxidation during annealing chemically via a physical or controlled environment during annealing via a cover or protective holder such as a stainless steel bag. For example, in a controlled environment, the bag will not be necessary.

The bag containing the tool steel was placed directly in the furnace at 1400 ° F. (760 ° C.) for 4 hours, heated from 1400 ° F. (760 ° C.) to 1850 ° F. (1010 ° C.) in 50 ° F. (10 ° C.) / Hour increments, 6 It is kept at 1850 ° F. (1010 ° C.) for a time. The bag was then removed from the furnace and air cooled to 650 ° F. (343.3 ° C.). At 650 ° F. (343.3 ° C.), the bags were placed in a furnace and cooled to 200 ° F. (93.3 ° C.) in 50 ° F. (10 ° C.) / Hour increments, and then air cooled once more to 120 ° F. (48.9 ° C.). Tempering occurs by placing the tooling in the furnace at 1000 ° F. (537.8 ° C.) for 6 hours and then air cooling to room temperature. Finally, the surface of the tooling is polished.

With regard to the hole including the central hole, the hardness of the block may be in the range of about 54 HRC to 63 HRC, and the hardness may be about 48 to 49 without the central hole. In general, as the hardness increases, the strength also increases, but the material also becomes more brittle. The estimated yield strength based on the hardness may be in the range of about 200 ksi (1378.9 MPa) to 220 ksi (1516.8 MPa).

While the use of tooling with intermediate annealing steps is shown in the examples below, the use of annealed blanks without any further annealing steps after starting machining operations on the blanks is within the scope of the present invention.

Exemplary Molding of Blanks into Cartridge

The blank 10 of FIG. 1 can be formed in the second state shown as the cylindrical cartridge 12 of FIG. 2 and into a final cylindrical shape after a number of pull reductions, for example to obtain final straight wall cylinder dimensions. For example, processing performed on austenitic stainless steel having a composition as described above for a blank having a diameter of 2 "(50.8 mm) at 0.01" (0.254 mm) thickness results in (1) a draw ratio of 1.7 and a diameter of 1.17 "(29.72 mm), (2) a draw ratio of 1.33 and a diameter of 0.88" (22.35 mm), (3) a draw ratio of 1.33 and a diameter of 0.665 "(16.89 mm) , (4) a draw ratio of 1.33 and a diameter of 0.500 "(12.7 mm) and (5) a draw ratio of 1.32 and a diameter of 0.378" (9.60 mm). This is then equal to the initial diameter divided by the final diameter This five-step sequential reduction is, for example, as described above, except that certain austenitic stainless steels may not require intermediate annealing between the forming steps. To those skilled in the art for the drawing of brass cartridges Although the five-stage process is described, it is within the scope of the present invention to use a more aggressive four-stage process and to exclude one of the reductions, which results in a draw ratio of 2, 1.4, 1.4 and 1.33 after each stage. Can cause.

Additional required molding operations include (1) forming a reduced neck diameter, (2) forming a cartridge rim, and (3) creating an area within the rim configured to receive a primer cap, for example. Includes work. Molding operations used may be those known to those skilled in the art that will be apparent in light of the teachings herein.

Yes

The blanks described in the examples below were preannealed. The initial blank was formed from the material going through 50% to 60% cold reduction followed by full annealing.

Example 1

Molding presses have been attempted on low carbon steels that are easy to mold, for example, having low strength with lower work hardening than higher order carbon steels and having a range of about 0.05 to 0.15 C. The 600 Kip (2668.9 kN) Tinius Olsen universal tester and hardening block were initially tested in low carbon steel, for example, initially with a blank with a 2.06 "(52.32 mm) diameter and a 0.04" (1.02 mm) thickness. Was used to perform. Starting at 100 Kip (444.8 kN), the blank is loaded in 50 Kip (222.4 kN) increments so that the final blank has a gradual taper to the edge with a 2.22 "(56.39 mm) diameter and 0.021" (0.53 mm) thickness. It had a thickness of 0.031 "(0.79 mm). A small blank with a diameter of 1.53" (38.86 mm) was then tested to obtain higher compressive stress for the same force. The final diameter for the small blank was 1.70 "(43.18 mm), the final center thickness was 0.0307" (0.78 mm), and the final edge thickness was 0.016 "(0.41 mm).

Example 2

ASTM specification T301 stainless steel blank was formed. The T301 stainless steel blank had mechanical properties closer to the austenitic stainless steel composition described above, while the T301 stainless steel blank had a higher work hardening rate. The T301 stainless steel blank had an original diameter of 1.53 "(38.86 mm) and an original thickness of 0.0472" (1.20 mm). Proceed to 300 Kip (1334.5 kN) in 100 Kip (444.8 kN) increments to final diameter of 1.625 "(41.28 mm), final center thickness of 0.045" (1.14 mm) and final 1/4 of 0.039 "(0.99 mm) Edge thicknesses were created Hard blocks were used as compression tools and were not shaped like this but were substantially flat for example Hard blocks were used because they were considered to be in the most suitable hardness range for this application. The hardness block was 42 HRC and slightly deformed after the molding was completed These blocks were replaced with blocks of 62 HRC The process was repeated to load 350 Kip (1556.9 kN) and unload at 400 Kip (1779.3 kN). The final diameter was 1.64 "(41.66 mm) with a hardness of 85-100 HRB. When annealed at 1825 ° F. (996.1 ° C.), the hardness dropped to 53-58 HRB. After the final loading to 400 Kip (1779.3 kN), the final diameter was 1.76 "(44.70 mm), the final center thickness was 0.043" (1.09 mm), the final edge thickness was 0.030 "(0.76 mm), and the final hardness was 90 to 93 HRB Hard blocks of 62 HRC eventually cracked, and thicker blocks are expected to be able to prevent these cracks Manufactured from S-7 tool steel and with a force of up to 2.4 million lbs (10675.7 kN) Another tooling to generate was used afterwards and did not crack.

Example 3

ASTM specification T305 stainless steel blanks were formed. The hardness block was replaced with a compression plate comprising one flat plate and a 0.5 "(12.7 mm) diameter center hole. The plate was machined from available D-2 tool steel.

The tooling was then engineered to include a central opening to manufacture the button 14 and was designed with replaceable compression inserts. The base was made from O-6 tool steel and the insert was made from D-2 tool steel, and both the base and insert were in the high 50 HRC warning range.

T305 stainless steel blank was formed by loading 250 Kips (1112.1 kN) in 50 Kip (222.4 kN) increments with full unloading between increments. Thickness was measured at three positions: center ("T1"), 1/8 "(3.175 mm) from the button (" T2 ") and 1/8" (3.175 mm) from the outer edge ("T3"). Final measurements were as follows: diameter = 1.61 "(40.89 mm), T1 = 0.048" (1.21 mm), T2 = 0.0414 "(1.05 mm) and T3 = 0.039" (0.99 mm). The material was then loaded at 300 Kip (1334.5 kN), 350 Kip (1556.9 kN) and 400 Kip (1779.3 kN), with the following final measurements, diameter = 1.63 "(41.4 mm), T1 = 0.048" (1.21 mm), T2 = 0.040 "(1.01 mm) and T3 = 0.039" (0.99m). The hardness at position T2 was approximately 59.3 HRA (96.5 HRB) and the hardness at position T3 was about 61.3 HRA (22 HRC). This test resulted in tooling cracks and center button dimpling up. Dimpled up was the result of the material being forced into the open area during compression. Thus, the desired thickening occurred with undesirable buckling, creating a realization of the need to control the height of the opening with more robust tooling. For example, the rod was inserted into an initial test opening in the tooling insert to form a button and allow for proper clearance. Spacers were used to control the height of the tooling relative to the blank in the vertical direction to prevent material from buckling. The height may for example be fixed or adjustable via a spacer.

Example 4

Plates or inserts with 0.5 "(12.7 mm) center openings were used on both the top and bottom of the tooling to handle dimples. Inserts for controlling height were used on one side only. 1.5" (38.1 mm) Another blank with a diameter of was loaded at 250 Kips (1112.1 kN) in 50 Kip (222.4 kN) increments with the following final measurements, diameter = 1.6 "(40.64 mm), T1 = 0.050" (1.27 mm), T2 = 0.0424 "(1.08 mm) and T3 = 0.090" (2.286 mm). The center button was not severely dimpled but swelled so that the top surface did not remain completely flat. Additional seams were added to the top surface of the rod inserted in the central opening of the tooling to lower the height of the insert and adjust the gap downward.

Example 5

Standard grade T305 stainless steel button blanks were used. The buttons were cold reduced at room temperature four times by intermediate annealing at 1850 ° F. (1010 ° C.) after each compression cycle. The blank was loaded at 400 Kips (1779.3 kN) (stress of approximately 205 ksi (1413.4 MPa) over surface area) in the first cycle, followed by 300 Kips (1334.5 kN) [stress of approximately 151 ksi (1041.1 MPa over surface area) ] Then loaded at 350 Kips (1556.9 kN) [stress of approximately 148 ksi (1020.4 MPa over surface area), followed by 375 Kips (1668.1 kN) [stress of approximately 155 ksi (1068.7 MPa over surface area)]. . After the fourth cycle, the average thinning was determined to be 39.7%. Annealing temperature was 1825 ° F. (996.1 ° C.) for 30 minutes for each annealing process.

With regard to the first machining operation, the original diameter was 1.5 "(38.1 mm) and the original thicknesses for T1, T2 and T3 were the same at 0.047" (1.19 mm) respectively. Final measurements after the first machining operation are as follows: diameter = 1.63 "(41.40 mm), T1 = 0.048" (1.22 mm), T2 = 0.414 "(10.52 mm), T3 = 0.039 (0.99 mm)". Hardness at T2 was measured at 97 HRB before annealing and 54 HRB after annealing at 1825 ° F. (996.1 ° C.).

With regard to the second machining operation, the starting measurement was the same as the final measurement for the first machining operation described above. Final measurements for the second machining operation are as follows: diameter = 1.7 "(43.18 mm), T1 = 0.0486" (1.23 mm), T2 = 0.0367 "(0.93 mm), T3 = 0.0332" (0.84 mm). The hardness after annealing was measured to 62.5 HRB at T2.

With regard to the third machining operation, the starting measurement was the same as the final measurement for the second machining operation described above. Final measurements for the third machining operation are as follows: diameter = 1.78 "(45.21 mm), T1 = 0.0494" (1.25 mm), T2 = 0.033 "(0.84 mm), T3 = 0.0295" (0.75 mm). Hardness at T2 was measured at 88 HRB before annealing and 76 HRB after annealing at 1825 ° F. (996.1 ° C.).

With regard to the fourth machining operation, the starting measurement was the same as the last measurement for the third machining operation described above. Final measurements for the fourth machining operation are as follows: diameter = 1.86 "(47.24 mm), T1 = 0.049" (1.24 mm), T2 = 0.0302 "(0.77 mm), T3 = 0.0265" (0.67 mm).

The insert of the tooling was initially cracked under the forming process prior to the base breaking. The force used was up to 400,000 lbs (1779.3 kN). The button blanks were expanded from about 1.5 "(38.1 mm) to about 1.9" (48.26 mm) and approximately 40% thinning was achieved by two intermediate annealing.

Example 5

As described above, austenitic stainless steel compositions of low work hardening properties were formed into blanks. Austenitic stainless steel was reduced to 0.060 "(1.52 mm) and annealed for another test set. The material was machined into a 1.5" (38.1 mm) diameter blank with a thickness reduction of about 20% in the first compression cycle. Tooling heat treated according to the exemplary method described above was used, the button blanks were subjected to intermediate annealing, and reduced in thickness several times as described below.

The sequence used was as follows. A compressive force of 350 Kips (1556.9 kN) was loaded, followed by annealing the material at 1950 ° F. (1065.6 ° C.), then loading at 425 Kips, followed by annealing at 1950 ° F. (1065.6 ° C.), followed by 475 Kips (2112.9 kN). And then annealed at 1950 ° F. (1065.6 ° C.), followed by 500 Kips (2224.1 kN), followed by annealing at 1950 ° F. (1065.6 ° C.). After each decrease, as shown in Table 2 below, the initial hardness of the 44.7 HRA was increased to an amount in the range of 54.2 HRA to about 63.5 HRA, and decreased to an amount in the range of 40.6 HRA to 44.1 HRA after each annealing. . The particle structure was examined after the fourth annealing and found to match the particle structure of the original material.

Table 2 shows the measurements taken for hardness after each reduction and annealing. The code represents four different button specimens tested, code 8 refers to the tested first button, code 16 refers to the tested second button, code 35 refers to the tested third button, and code 46 tested Refers to the fourth button.

Referring back to the tested sequence, after the first reduction, the center thickness was measured at 0.0629 "(1.6 mm), the percent thinning of the outer area was measured at 19.79%, and the diameter was measured at 1.64" (41.66 mm). After the second reduction, the center thickness was measured at 0.0653 "(1.66 mm), the percent thinning of the outer area was measured at 32%, and the diameter was measured at 1.75" (44.45 mm). After the third reduction, the center thickness was measured at 0.0681 "(1.73 mm), the percent thinning of the outer area was measured at 41.24%, and the diameter was measured at 1.87" (47.50 mm). After the fourth reduction, the center thickness was measured at 0.0695 "(1.77 mm), the percent thinning of the outer area was measured at 46.50%, and the diameter was measured at 1.95" (49.53 mm).

In addition, some sequences are finally loaded at 600 Kips (2668.9 kN) and this higher force results in about 5%, or only 50%, total thinning addition of thinning. For example, the button blanks were cold reduced four times with intermediate annealing after each forming stage and compressed to a stress level of about 180 ksi (124.1 MPa) at each stage. The total reduction level had a final diameter of about 2.1 "(53.34 mm) and was only greater than 50% achieved.

While various embodiments of the invention have been shown and described, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by those skilled in the art without departing from the scope of the invention. Many of these potential modifications are mentioned, and others will be apparent to those skilled in the art. For example, the examples, embodiments, geometric shapes, materials, dimensions, ratios, steps, and the like described above are illustrative. Accordingly, it is to be understood that the scope of the present invention should be considered in light of the following claims, and should not be limited to the details of the structure and operation shown and described in the description and drawings.

10: cartridge blank 12: cartridge
14: Center button 16: Outside area
18: base 20: side wall
22: arm 24: shaft
26: head 42: shaft
44: arm 50: press
52: upper block 60, 62, 64: wall

Claims (10)

Ammunition cartridge,
(a) a base having a first thickness; And
(b) an outer region having a second thickness, the outer region comprising the outer region wherein the first thickness is greater than the second thickness by a ratio of at least 50%,
The cartridge comprises austenitic stainless steel,
Wherein said base and said outer region comprise a monolithic piece of austenitic stainless steel. The cartridge of claim 1, wherein the second thickness is about 50% to 80% less than the first thickness. The cartridge of claim 1 wherein the second thickness is about 50% to 60% less than the first thickness. The cartridge of claim 1, wherein the austenitic stainless steel comprises, by weight percent, Cr of about 17.2 to about 17.8, Cu of about 3.1 to about 3.4, and Ni of about 8.1 to 8.4. As a method for forming an ammunition cartridge,
(a) forming a blank having a button and an outer region and a central axis, the outer region surrounding the button at its periphery, the outer region and the button of the blank being substantially perpendicular to the central axis Forming the blanks, each having a linear base;
(b) forming an underside of said outer region in a direction downward toward said central axis until said outer region is substantially parallel to said central axis. 6. The method of claim 5 wherein the forming process for the blank comprises at least one of spin forming or compression molding. 6. The method of claim 5 wherein the forming process for the blank comprises grinding. 6. The method of claim 5 wherein the blank is preannealed. 6. The process of claim 5 wherein the forming process for the blank comprises tooling compression by tooling comprising a pair of blocks and a pair of inserts, each block receiving a respective insert And a cartridge cartridge forming method. 10. The method of claim 9, wherein the at least one insert includes a central hole in itself.

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