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Publication numberUS3703094 A
Publication typeGrant
Publication dateNov 21, 1972
Filing dateJun 24, 1971
Priority dateJun 24, 1971
Also published asCA960560A1
Publication numberUS 3703094 A, US 3703094A, US-A-3703094, US3703094 A, US3703094A
InventorsCree George Benson Jr
Original AssigneeCree George Benson Jr
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Brake press die system, structure and processes
US 3703094 A
Structures are provided each having a high modulus of resilience as well as improved metallurgical gradients and physical characteristics and resulting sufficient resilience to avoid damage by impact stresses, while sufficiently hard and mechanically stable to maintain their dimensional stability.
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Cree, Jr. 1 Nov. 21, 1972 [54] BRAKE PRESS DIE SYSTEM, 3,007,508 11/1961 Giordano ..72/386 STRUCTURE AND PROCESSES 3,214,955 11/1965 Voth ..72/389 3,342,060 9/1967 Peterson ....72/470 [72] g 'ggg ff g $56 3,610,019 10/1971 Denninger ..72/386 [22] Filed: June 24, 1971 Primary Examiner-Richard J. Herbst Assistant ExaminerGene P. Crosby [21] 156360 AttorneyEly Silverman [52] US. Cl ..72/389, 72/475 [57] ABSTRACT [51] Int. Cl. .3211! 37/10 s tructures are provlded each havmg a high modulus of [58] Flew of Search 352 resilience as well as improved metallurgical gradients and physical characteristics and resulting sufficient resilience to avoid damage by impact stresses, while [56] References cued sufi'iciently hard and mechanically stable to maintain UNITED STATES PATENTS their dimensional stability. 435,986 9/1890 Tucker ...72/475 10 Claims, 13 Drawing Figures PATENTEDnum m2 703,09

sum 1 or 3 INVENTOR.

34.. 34.2 659565 B. CREE JR ATTORNEY PATENTEDHOYZI 19R 3.703094 SHEET 3 [IF 3 F /G. 8 F /G. 9


ATTORNEY BRAKE PRESS DIE SYSTEM, STRUCTURE AND PROCESSES BACKGROUND OF THE INVENTION 1. Field of the Invention The field of invention to which this invention pertains are metalworking wherein an iron containing sheet is adjacent an aluminum containing component. metal deforming, and metallurgical apparatus for treating solid metal.

2. Description of the Prior Art In the use of dies during brake press operation the male or punch dies are subjected to repeated compressive impact stresses while the female or bed dies are subjected to repeated compressive and bending impact stresses that are applied rapidly to and by the work against which such dies are used. Such impact stresses reach high values and, as is well known, cause fatigue failures of the dies.

Certain minimum hardness of die 'materials is required to prevent excessive wear yet conventional materials used for dies and having such degree of hardness have only limited fatigue strength.

Soft materials, as rubber used in rubber pad forming, wear too rapidly to be economical and do not produce sharp comers or bends adequately and consistently. Another approach to metal forming has been high speed forming. However, such rapid speed operation provides heat effects on the worked parts and such high. speed treatment work hardens and makes brittle the treated sheet.

SUMMARY OF THE INVENTION Multi-component aluminum alloy dies of high modulus of resilience are provided with a hard pellicles. The dies are resilient throughout their interior mass although the points of contact are made particularly hard and the zones of high tensile stress particularly strong. Accordingly, such dies are able to deform elastically during an impacting (press brake) operation so as to gradually, considering the speed of changes involved in a metal working stroke, apply force and absorb force and avoid absorption of mechanical energy over only very small die areas and volumes which absorption might create localized generation of extreme heat, crystallization effects and grain structure changes as might change the structure and mechanical action of such alloy dies. The metallurgical compositions are particularly treated to provide such structure and operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a transverse section of a male brake press punch die according to this invention.

FIG. 2 is a side view of a transverse section of another brake press punch die according to this invention.

FIG. 3 is a side view of a transverse section of a female brake press die according to this invention.

FIG. 4 is an overall view of mechanical press brake in which the punches and dies of FIGS. 1-3 are used.

FIG. 5 is a curve of tensile strength relative to rate of cooling of alloy materials used in apparatuses of FIGS. 1, 2 and 3.

FIG. 6 is a graph of effect of thickness and quenching media on average cooling rates at midplane of alloy material of apparatuses of FIGS. 1-3.

FIG. 7 is a graph of tensile strength vs. hardness of alloy material of apparatuses of FIGS. 1-3.

FIGS. 8 and 9 show a sequence of steps in a brake press operation using the dies of FIGS. 1 and 3, as end VIQWS.

FIG. 10 is a diagrammatic showing of the shoulder zone 10A of FIG. 9 during a sequence of steps as in FIGS. 8 and 9.

FIG. 11 is an extrusion die according to this invention.

FIG. 12 is a hammer head according to this invention.

FIG. 13 illustrates a combination of piston rod and piston according to this invention.

FIGS. 1 and 5 are shown partially in perspective. The plan views of FIGS. 2 and 3 are to scale.

DEFINITIONS Brake press forming is a process in which the working piece is placed over an open die and is pressed down into the die by a punch that is actuated by the ram portion of a machine called a brake.

As to directionality:

Longitudinal means parallel to major dimension of direction of working of section.

Long transverse" means to direction of working in parallel to width of section.

Short transverse means 90 to direction of working and parallel to thickness or minimum dimension of section.

Transverse" means 90 to direction of product having axial symmetry.

Rockwell hardness:

A diamond cone penetrator (l20) with a slightly rounded tip (radius 0.2 mm) is loaded with a minor load of 10 kg., primarily to seat the penetrator; a major load (regularly 150 kg. for C scale) is applied and released after a specific time, usually 10 sec. The hardness is measured by the difference in depth of the major and minor loads.

Brinell Hardness number conversion: For Rockwell numbers C20 to 40:

Brinell hardness number 1,420,000/( Rockwell C number) 2 For Rockwell numbers greater than C 40:

Brinell hardness number 25,000 I I00 Rockwell C Number (21) DESCRIPTION OF THE PREFERRED EMBODIMENTS TABLE I working in Tensile strength p.s.i. Yield strength p.s.i. Elongatioufb in 2 in.

SL000 $8,000 71,000 -7B.000 l0 Shear strength p.|.i 49,000 -52,000

Modulus of elasticity 10.4 X lbsJin.

Surface hardness (500 kg. load 160 Brinell 10 MM Bali) Thermal conductivity Component I: by Weight Range Mn .30 Si .40 Fe .50 Cu 2.0 1.6-2.4 Mg 2.7 2.4-3.1 Cr .30 -.35 Zn 6.8 6.3-7.3 Al .szma uqst.

While the extrusion provides that each section, as shown in FIGS. 1, 2 and 3, transverse to the length of the die as 11, 21 and 31, respectively, (which direction of length, as 81 (FIG. 1), is the direction of extrusion) has similar mechanical properties along the length of the die, these alloy extrudates are heat treated after forming into shapes as shown in FIGS. 1, 2 and 3 and are not, accordingly, in their final form homogeneous in all characteristics throughout all parts of each such sections along the long transverse direction thereof as 82 in FIG. 1 or along their short transverse direction as 83, and have physical and microstructure characteristics that vary as hereinbelow described. The alloy extrudates in final form, although composed primarily of aluminum are composed also of zinc, magnesium and copper insolid solution and/or precipitated in such finely divided form as to be substantially invisible up to about 100 X power although some magnesium silicide (mg, Si) is visible.

These extrusions are made with sufficiently rounded corners to avoid development of cracks in the anodized coating although such coatings are porous, as shown by electron microphotograph. V

The extruded surfaces, as 18.1 and 18.2 and 28.1 and 28.2 and 37.3, 38.2 and 38.1; i.e., are not even wrinkled, as seen under SOXX magnification and free of Luder lines.

The straight punch, 11, is composed of an elongated straight punch body portion 12, punch cross 13, punch tail 14 and punch head operatively combined into an integral unit. The head 15 has a wide shoulder portion 16 and terminates in a punch nose 17.

FIG. 1 is the outline of one of a group of such dies; dimensions of other dies of generally the same configuration are set out in TABLE III. The tail portion 14 has an upper left edge 14.1 and an upper right edge 14.2, a

lower left edge 14.3 and a lower right edge 14.4 with a between edges 13.1 and 13.3 and a right cross face I between edge 13.2 and 13.4.

The punch shaft portion 12 has a left. upper edge at corner 12.1, and a right upper edge at corner 12.2, a left lower edge at corner 12.3, and a right lower edge at corner 12.4, and a left shaft face, 12.5, between corners 12.1 and 12.3, and a right shaft face, 12.6, between corners 12.2 and 12.4.

The punch head 15 has a wide shoulder 16 with an upper left edge 16.1 and a lower left edge 16.3 and an upper right edge 16.2 and a lower right edge 16.4, and a left shoulder face between edges 16.1 and 16.3 and a right shoulder face between edges 16.1 and 16.3 and a right shoulder face between edges 16.2 and 16.4. p

The punch nose 17 is located below the punch shoulder and spaced from the edges 16.3 and 16.4 by lefl punch face 18.1 and right punch face 18.2 and has a small but definite radius of curvature.

The gooseneck punch, 31, is composed of an elongated gooseneck body portion 22, gooseneck cross 23, gooseneck tail 24 and gocseneck head 25 operatively combined into an integral unit. The gooseneck head 25 has a wide shoulder portion 26 and terminates in a nose 27.

FIG. 2 is the outline of one of a group of such dies; dimensions of a die of such configuration are set out in TABLE IV. The tail portion 24 has an upper left edge 24.1 and an upper right edge 24.2, a lower left edge 24.3 and a lower right edge 24.4 with a top tail face between edges 24.1 and 24.2 and a left tail face between edges 24.1 and 24.3 and a right tail face between edges 24.2 and 24.4.

The gooseneck cross portion 23 has an upper left edge 23.1 and an upper right edge 23.2, a lower left edge 23.3 and a lower right corner 22.2, and a right middle edge 23.6, with a left shoulder face between edges 23.1 and 23.3 and an upper right face between edges 23.2 and 23.6 and a right lower shoulder face between edges 23.6 and 22.2.

The gooseneck shaft portion 22 has a left upper edge at corner 22.2, and a right upper edge at corner 22.2, a left lower edge at corner 22.3 and a left lower edge at rounded corner 22.4, and a left shaft face, 22.5, between comers 22.1 and 22.3, and a right shaft face 22.6 between corners 22.2 and 22.4.

The gooseneck nose 27 is located below the shoulder 26 and spaced from the edges 26.3 and 22.4 by left gooseneck punch face 28.1 and lower right gooseneck punch face 28.2 and an upper right gooseneck punch face 28.3. The nose 27 has a definite but small radius of curvature.

The .bed or base or female die 31 is composed of a vertical straight die body portion 32, die tail 34 and die head 35 operatively combined into an integral unit. The die head 35 has a left shoulder 36 and a right shoulder 37 on either side of a die groove 38.

P16. 3 is the outline of one of a group of such dies; dimensions of two such dies according to this invention are set out in TABLE V.

The tail portion 34. has an upper left edge 34.1 and an upper right edge 34.2, a lower left edge 34.3 and a lower right edge 34.4, with a bottom tail face between edges 34.2 and 34.4 and a left tail face between edges 34.1 and 34.3 and a right tail face between edges 34.2 and 34.4.

The body portion 32 has a lower left edge 32.1, and a lower rightedge 32.2, with a left body face between edges 32.1 and 36.1 and a right body face between edges 32.2 and 37.2.

The die head 35 has a left shoulder 36 with an upper left edge 36.1 and an upper right edge 36.2 and a flat upper left shoulder face between edges 36.1 and 36.2.

The die head 35 has a right shoulder 37 with an upper right groove face 38.2; faces 38.1 and 38.2 join a curved groove apex 39 at the bottom of groove 38 and join edges 36.2 and 37.1 at their tops.

The hardness of different points on the exterior surfaces and transverse sections of such dies as illustrated IN FIGS. 1-3 were tested with results as at TABLE II. Generally, in the dies so formed the greatest hardness is at the nose*, and the exterior surfaces other than at the nose are softer than at the nose and the core is even softer than the surfaces other than at the nose. (*Edges 37.1 and 36.2 would be nose of unit 31).

The high thermal conductivity of the aluminum alloy (about 1500 B.T.U./hr./sq. ft./F./inch at 400 F. (while steel is only 300 T.T.U./hr./sq. ft./F./inch) provides that, while heat transfer during quenching is generally limited by resistance at the surface in contact with the quenching medium a substantial thickness of the die body of the alloy as 7178-T-6 is, by quenching, brought to sufficiently high tensile strength and hardness to provide the high modulus of resilience desired as shown in the particular examples herein. For creation of similar properties in other die shapes, the relation of tensile strength to hardness for the aluminum alloy used is set out in FIG. hereof so that the desired tensile strength may be determined and checked conveniently. Also, the relation of quench rate to strength is set out in FIG. 5 hereof for two different alloys, 71 7;T- and 7075, so that the quench rate for different portions of the die may be chosen to provide the desired hardness of different portions thereof; e.g., at the nose and other outer surfaces of the dies made as herein described. The quench rate used is achieved by the cooling rate shown in FIG. 6 hereof.

The dies, as 11, 21 and 31, each have a fibrous external surface layer of large recrystallized grains, which constituent particles are elongated in direction parallel to extrusion direction, (as 81 in FIG. 1)while the center of each such extruded mass sufiers minimum deformation. In the extrusion process, while there is some recrystallization, the 7178 alloy used, like other of al. Zn-Mg-Cu alloys of the 7xxx series show the least recrystallization and develop high mechanical properties in the major portion of the extruded cross section.

In such heat treated structure where the structure is primarily unrecrystallized, tensile properties in the transverse direction, as 82 and 83, are significantly lower than longitudinal properties along direction 81. Thus, the tensile strength is reduced in transverse directions 82 and 83 relative to longitudinal strength.

Anodic protection and surface hardening is provided to apparatus as shown in FIGS. 1-3 by treating the extruded and quenched die by the following procedure.

The anodizing treatment uses 8-25 percent sulfuric acid with a peat additive, at 2535 F., at current density of 24-36 amperes per square foot in stepped voltage increments with 20 volts D.C. starting stepped up to 90 volts at rate of 1 volt per minute; the oxide formation rate is 30 minutes per mil thickness, in conventional manner (as taught at pages 653 to 656 of Aluminum: Fabrication and Finishing, Volume 3 under Hard Anodic Coatings) The results of the anodizing treatment are tested by standard procedures as ASTM B110, ASTM B136, ASTM B133 and ASTM B244.

While these anodized surfaces are hard, their thickness is only a few l to 5) thousandths of an inch and, as viewed under the electron microscope, porous. Accordingly, the anodic coating does not interfere with the mechanical yieldability of the die material below and supporting such coating and consequent high modulus of resilience and ability to absorb impact energy the anodic coating thus is not separated from its mechanical support and so provides continued electrolytic protection thereto, and, thereby, corrosion resistance, notwithstanding the stresses applied to such dies during normal usage thereof.

This anodic cladding provides electrochemical protection for the core at exposed edges and abraded or corroded areas.

The modulus of resilience is defined as Sf/ZE where S is the elastic limit. The modulus of elasticity of the alloy 7178-T-6 used in elements 11, 21 and 31 is only slightly lowered by the magnesium zinc, silicon, and copper added to pure aluminum and is about 10.4 X 10 psi. Thus, the ability of the material of the apparatus 11, 21 and 31 to absorb impact is several times higher than would be provided by such shapes formed of steel of a comparable Brinell number. Steels which exhibit comparable Brinell numbers have, for steel, a tensile strength of 75,000 to 90,000 pounds per square inch, so that on this basis the modulus of resilience of apparatuses 11, 21 and 31 are between seven and nine times that of steel of comparable Brinell number.

Because of the excellent thermal conductivity of aluminum alloys as used in the apparatuses as shown in FIGS. 1-3, the stroke by the nose of the die, notwithstanding the creation of any localized temperature effects through the mass of such dies (as 11 and 31). However, the thermal conductivity of this alloy material is especially effective in permitting, also, even and deep cooling rates whereby the nose of the punch and zone below the groove 38 and apex 39 of the die 31 are particularly rapidly cooled and hardened, while the body of the die is not, and the distribution of hardness as described for apparatus of FIGS. 1-3 is achieved.

In brake press operations with the dies of this invention, the punch or male die, as 11, is firmly placed in clamp 61 of the movable ram 66 of conventional brake press and the female or base die as 31 is placed in the lower jaw or bed 62 of the press, 60; then the work piece as 41 is placed in the maw or opening 65 over the groove as 38 and supported on and in contact with the base die shoulders 36 and 37; the drive motor 64, through clutch 71, flywheel as 72 and gears as 73 drives the upper punch die downward relative to brake press housing 74 toward the apex 39 of the groove 38 in the lower base or female die 31. Adjustment of the height of the ram is made by a ram adjusting motor as 76 and adjustment screws as 77.

After the tools have been thus set up and the sheet height adjusted, the press brake is cycled and the to-beworked metal as sheet 41 is bent to the desired angle around the nose radius of the punch used. The distance the ram punch (male die) as 11 travels into the bed die (female die) 31 determines the bend angle of the work piece; such distance of entry by the punch is determined by the shut height of the brake press machine and the span width or width of the die opening.

The span width of the female die, as 31; i.e., the distance between the top surfaces of base shoulders 36 and 37 (between edges 36.2 and 37.1) and thickness of the work piece determine the force needed to bend the work piece 41. The mechanical wear of the dies determines the constancy of angle formed.

The width of each of the male dies or punches, 11 and 21, is far greater than any portion thereof; i.e., nose 17 and 27, that contacts the work piece: only the nose forcefully contacts the work piece; the remainder of the width of the male die or punch (along'direction 83 of FIG. 1) primarily provides for rigidity and convenient and reliable positioning and such punch die body has a compressive yield strength far in excess of impact stresses applied thereto: the large volume and transverse cross-section thereof and ability to yield permits a distribution of the compressive stresses applied thereto relatively evenly throughout the mass between the nose and the shoulder and, in combination with the high thermal conductivity of the mass, avoids any metallurgical changes due to the temporary stresses met, as in 31, also.

The female portion of the die, as in FIG. 3, is hard surfaced at surfaces 38.1, 38.2, and along curved edges 37.1 and 36.2. The portions of the die that successively contacts the work are diagrammatically illustrated in FIGS. 8, 9 and as there illustrated, as the work piece 41 is bent by the male die 11, the portions SSA, 55B and 55C of the work piece 41 supportedlon the female die shoulder edges 36.2 and 37.1 move horizontally and vertically toward the nose of the male die to contact the shoulders at different lines of contact, as 57A, 57B and 57C, respectively along planes 155A, 1558 and 155C, respectively.

The forces of the impact of the downward motion of the male die, 86 and 87, on the shoulders 36 and 37 of the female or base die 31 is met by the supporting upward center force 88-along the tail of the female die and a tensile force 89 is directed horizontally across the body of the female die below the apex 39 of the female die groove or notch 38: the high thermal conductivity of the aluminum alloy 7178 permits, by rapid quenching of the extruded female die as herein provided, a broad band of high tensile strength material (indicated by the high hardness measurement) below the surfaces 38.1, 38.2 and apex 39 to resist tensile stresses applied thereto without stress concentration as might cause fatigue failure. The band is at least A inch wide.

In operation the surface temperature of sheet 41 of 3/64inch -3l16 inch steel stock rises only to 125l35 F. (which is well below the transition temperature of the alloy used) along line of contact of the shoulders 36 and 37 and the work piece (lines 56 and 57 in FIG. 9) during operation of brake presd due as 60 with dies at room temperature of 6080 F.

While the 7l78-T-6 alloy is preferred another alloy composition which may be used herein, and is known as 7075-T-6; it has the following characteristics and composition:

Modulus of elasticity l0.3 X 10' p.s.i Tensile strength 81,000 p.s.i. Yield strength 72,000 p.s.i. Elongation, I: in 2 in. 14.0 Brinell Hardness I60 Component 1: by Weight it]. Remainder In the operation of deforming, shown in FIGS. 8, 9 and 10, the workpiece 41 is struck on the upper surface 42 thereof with the vertically downwardly moving nose 17 of the punch 11, which has a large modulus of resilience (about 300 in. lbs. per cu. in. Concurrently, lower surface 44 of piece 41 is supported on unit 31 shoulders at zones 56 and 57, spaced apart along direction and distance between edges 36.1 and 37.1 transverse to direction of movement of nose 17. Zones 56 and 57 are indicated by points on FIG. 9 because these zones are so thin as to be lines.

The mass of the ram 66 of the press 60 to which the punch die 11 is attached drives the punch die 11 toward and downwardly into groove 38 downward forcefully and rapidly. The force thereof (86 and 87) is initially met, as in FIG. 8, when the nose 17 first contacts upper surface 42, by a combination of tensile forces parallel to surfaces 38.2 and 38.1 and compressive forces opposite 86 and 87 perpendicular to top shoulder surfaces. As the punch moves further downward as shown in FIG. 9, the elastic limit of the sheet 41 is exceeded, the plane of the bottom surface 44 moves adjacent each shoulder, 36 and 37, as shown for 37, from surface 137.3 (an extension of surface 37.3) to plane A to plane 1558 to 155C. As the increments 55A, 55B and 55C of work piece 41 successively move centrally of the shoulder edges 36.2 and 37.1 as shown for shoulder edge 37.1, (a) the angle to thehorizontal of planes 155A, 1558 and 155C, respectively, of the bottom surfaces 57A, 57B and 57C of plate 41 portions 55A, 55B and 55C contacting each shoulder surface, as 37, increase, and (b) the lateral component of force applied to the shoulders, as 36 and 37, accordingly increase from (i) the direction of a force, as 87, normal to the surface 37.3 (the top of shoulder 37) and parallel to a line, as 137.3 normal to surface 37.3 to (ii) directions 255A, 255B and 255C which have increasing horizontal components.

A yielding base die, as 31, with a low (about 10.4 X 10 p.s.i.) modulus of elasticity provides a lesser initial force of the die 11 against plate 41 and of plate 41 against die 31 than does a steel die, (of greater modulus of elasticity; i.e., 30 X 10 p.s.i.) because it takes about three times as long for the vertical displacement of the plate to develop against the alloy die as against a steel die; hence, the initial shock or impact of the ram is proportionately substantially decreased, although the tensile strength across the die 31 is adequate to maintain its dimensional stability and permit rapid punching action; e.g., one to three strokes per second without thermal or mechanical damage. The wear and fatigue resistance of the dies, as 31, 11 and 21 are accordingly far greater than provided by steel dies of comparable modulus of resilience or surface hardness. The strain suffered by nose 17 and shoulders 36 and 37 equals the square root of the quotient of:

a. square of stress applied (which stress equals elastic strength divided by strain) divided by:

b. twice the product of:

i. modulus of elasticity of the alloy, times ii. modulus of resilience of the alloy.

. Additionally, the extensibility (low value of E) alloy used for die 31 allows a progressive yet elastic lateral displacement of the faces 38.1 and 38.2 during movement of the nose 17 towards apex 39 and reduces the frictional drag between the centrally moving increments of surfaces as 55A, 55B and 55C of the bottom surface 44 and the shoulder edges 36.2 and 37.1. Accordingly, the yieldability of the alloy of die 31 limits stretching of the work piece 41 between (a) the nose as 17 and (b) the zones or lines of contact of the sheet 41 and shoulders 36 and 37 and so avoids hardening and/or rupture of the work piece 41.

Another application of the process of deforming metal herein disclosed is in the operation of an extrusion press, as shown in FIG. 11, where an extrusion punch die 91 with a lower face 97 and cylindrical side face 96 operates to deform a steel sheet 94. The body of the die 91 is made of 7178-T-6 alloy with a bottom surface hardness of 38 Rockwell C and hardened, as 11, to a depth of 16 inch. The interior of the die 91 would have a hardness of about 6 Rockwell C. The female die 93 would have a hardness of 38 Rockwell C at the edge of its circular shoulder 99, and have a 34 Rockwell C hardness and comparable tensile strength in a band 6 inch deep around the perimeter of the die orifice 98 to achieve the blunting of the die impact while providing the needed tensile strength and energy absorption characteristics above-described for dies 11 and 31.

The hammer head 85 shown in FIG. 12 is another example of an impact applying tool within the scope'of this invention which is made of alloy as used in FIG. 1 and is particularly used for removing dents from steel automobile fenders. Such tool 85 would have a hardness at its head 84, of 28 to 48 Rockwell C to a depth of is inch and an interior hardness between 4 and 6 Rockwell C.

The combination 130 of a piston connecting rod 131 with pin 141 and a piston 140 as shown in FIG. 13 is also included within the scope of this invention. The piston 140 is cylindrically shaped as conventionally used in a water cooled automotive engine and includes a piston pin or wrist pin, 141, which pin is a solid cylinder supported at its ends on bosses supported on walls of the piston. The hardness of the bearing surface 139 of the connecting rod 131 at its upper or wrist pin end in contact with and adjacent the piston pin 141 is formed in range of 28-48 Rockwell C by procedure above described and the bearing surface 142 thereof to be in contact with the crankshaft 143 is also formed in range of 28 to 48 Rockwell C by the same procedure.

Connecting rod 131 is formed of the 7178-T-6 alloy hereinabove described and is heat treated to provide hardness in its core 138 in range of 6 to 8 Rockwell C and, as in the dies 11, 21 and 31 herein described, has a modulus of resilience of about 300 in.-lbs. per cubic inch.

The piston pin 141 is made of the same alloy and is heated to have the same hardness at its bearing surface adjacent 139 and in its core, and also has a modulus of resilience of about 300 in.-lbs. per cubic inch, as does the connecting rod 131.

TABLE I1 Rockwell C I-IARDNESS (a) Taken on Hardness Measurements (b) w Piece No. Surface Core Nose Depth 11 (d) 9((101) 6(104) 48(107) 8(108) -(6) 12(102) 4(105) 28(111) 9(109) 31 (d) 19(103) 17(106) 38(112) 32(110) (a) Data taken with Clark Hardness Tester. Rockwell C. Brale diamond penetrator. major load Kg.; tester described in United States Patents 2.319.208and 2.326.759.

(b)Measurements taken at points and surfaces indicated in parenthesis at positions as on each ofFlGS. 1, 2 and 3. Item 41 is a 3/64 thick steel sheet for dies 11 and 31.

(c) Piece tested was anodically coated as described in text herein to thickness of two mils; items 11 and 31 tested as in this table were not coated. for purpose of comparison. although such is usual treatment. (d) Impact tests have been run. and where steel dies split, the dies as 11 and 31 made according to this invention survived.

321p of nose to line 13.1-13.2 and/or line between edges 14.3 and TABLE IV Dimensions of Embodiment No. 31. Edge to edge notation Distance (inches) 23.4-23.2 (horiz. dist.) 1.50 24.1-24.2 .5 24.2-24.4 .625 22.3 .125"R 23.1 .188"R 23.6 .438"R 22.4 .312"R 23.4-24.3 (vertL) .50 24.3-27 3.750 23.4-26.1 1.812 26.1-26.3 0.50 27 .062"R 28.2(width) 28.1283 .312"

TABLE IV Dimensions of embodiment 31 and the like Embodiment 31' No. 31 Edge to edge distance Measurements in inches 34.3-34.4 .50 .50 34.1-34.3 .625 .625 34.1-37- 2.250" 1.75 surface 36.1321 to 2.0 1.25 surface 37.1-32.2 37.1-36.1 1.50" .625 37.1 .031" .125 38.1,ang1e to horiz. 45 44 39 .063"R .02R 32.1 .375R .03R 36.1 .12$"R .125R

1 claim:

1. Process of repeatedly deforming successive portions of metal sheet by striking one surface of work of such portions with semi-rigid resilient member at one zone in one direction while supporting the sheet on a compression member on a surface of said sheet opposite tosaid one surface at zones spaced apart from the said first zone along a direction transverse to said one direction and deforming the sheet while applying stress to said compression member according to the formula:

\I F {(2 x E x M) where A= FIE 5. Process as in claim 4 wherein said metal sheet is a steel sheet.

6. Process as in claim 5 wherein said member is an integral impact applying tool with a surface hardness of 160 Brinell and is composed of an alloy of the folling composition:

Component '1: by Weight Mn 30 Si 40 Fe .50 cu Range of l.6 2.4 Mg Range of 2.44.] Cr Range of .l8-.35 Zn Range of 6.3-7.3

al. Remainder 7. An integral impact applying tool with a surface hardness of Brinell and a modulus of resilience of at least 300 inch pounds per cubic inch and a modulus of elasticity of about 10.4 X 10' p.s.i.

8. Apparatus as in claim 7 comprising a brake press punch with a maximum hardness at its nose and a lesser hardness at other points on its surface and a lesser hardness internally, the hardness at the nose extending to a depth of 56 inch.

9. Apparatus as in claim 8 in combination with a female die having 2 spaced apart shoulders and a groove therebetween, and said groove, surface and shoulders having a like hardness and resilience to a depth of at least inch.

10. Apparatus as in claim 9 composed of an alloy of the following composition Tensile strength p.s.i. 81900-88000 Yield strength 7 l DUO-78,000 Elongation k in 2 in. 10 Shear strength, p.s.i. 49000-52000 Modulus of elasticity 10.4 10' Surface hardness (500 kg. load 160 H) mm. Bail) Thennal conductivity .57 cal/sq. e-Je-JleeJ" C ("2.7 BTU/sq. fL/hrJflJ'F. Component k by Weight Range of 1.6-2.4 8 Range of 2.4-3.1 Cr Range of.l8 .35 Zn Range of 6.3-7.3 al. Remainder

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US435986 *Apr 29, 1890Sep 9, 1890 Die for making lathing
US3007508 *Sep 5, 1956Nov 7, 1961PromecamSheet-metal bending press
US3214955 *Nov 14, 1961Nov 2, 1965Foundry Equipment CoSheet metal bender
US3342060 *Dec 15, 1964Sep 19, 1967Peterson Roswald MIndexing of dies
US3610019 *Feb 16, 1970Oct 5, 1971Denninger WalterBending brake
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4753099 *Sep 5, 1986Jun 28, 1988Trumpf Gmbh & Co.Bending press for sheet metal
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U.S. Classification72/389.3, 72/475, 92/222
International ClassificationB21D37/00, B21D5/02, B21D5/01, B21D37/10
Cooperative ClassificationB21D37/10, B21D37/00, B21D5/02, B21D5/01
European ClassificationB21D37/00, B21D5/02, B21D37/10, B21D5/01