US3793911A

US3793911A - Extrusion die and method for making the same

Info

Publication number: US3793911A
Application number: US00293886A
Authority: US
Inventors: F Fuchs; P Venkatesan
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1972-10-02
Filing date: 1972-10-02
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26

Abstract

Rod-extruding die has toughness gradient increasing from the throat end to entrance end, and hardness or compressive strength gradient increasing from entrance end to throat end. Die may be cut (1) from non-uniformly work-hardened billet, (2) from nonuniformly-quenched heat-treatable billet, (3) from sintered billet produced by cofiring plural layers of sinterable powders having different post-sintering characteristics of toughness and hardness and arranged to provide toughness and hardness gradient in billet, (4) from billet produced by brazing plural elements having different characteristics of toughness and hardness and arranged to provide toughness and hardness gradient in billet. Die may also be formed by molding and compacting plural layers of sinterable powder material having different post-sintering toughness and compressive strength characteristics, in the form of the die, and cosintering to produce the die, the layers being arranged to provide a toughness and a hardness gradient in the die.

Description

United States Patent Fuchs, Jr. et al.

[ Feb. 26, 1974 EXTRUSION DIE AND METHOD FOR MAKING THE SAME [75] Inventors: Francis Joseph Fuchs, Jr.;

Peruvemba Swaminatha Venkatesan, both of Princeton, NJ.

[73] Assignee: Western Electric Company Incorporated, New York, NY.

[22] Filed: Oct. 2, 1972 [21] Appl. No.: 293,886

' Related US. Application Data [62] Division of Ser. No. 150,496, June 7, 1971.

[52] US. Cl 76/107 R [51] Int. Cl B2lk 5/20 [58] Field of Search 76/107 R, 107 A, 107 AS [56] References Cited UNITED STATES PATENTS 2,058,] 10 l0/l936 Schroter et a1. 76/107 A 2,066,372 l/l937 Tomalis 76/107 R 1,784,866 l2/l930 Fahrenwald.... 76/107 R 1,992,905 Wills 76/l07 R Primary Examiner-Harrison L. Hinson Attorney, Agent, or Firm-Jack Schuman 5 7 ABSTRACT Rod-extruding die has toughness gradient increasing from the throat end to entrance end, and hardness or compressive strength gradient increasing from entrance end to throat end. Die may be cut (I) from non-uniformly work-hardened billet, (2) from nonuniformly-quenched heat-treatable billet, (3) from sintered billet produced by cofiring plural layers of sinterable powders having different post-sintering characteristics of toughness and hardness and arranged to provide toughness and hardness gradient in billet, (4) from billet produced by brazing plural elements having different characteristics of toughness and hardness and arranged to provide toughness and hardness gradient in billet. Die may also be formed by molding and compacting plural layers of sinterable powder material having different post-sintering toughness and compressive strength characteristics, in the form of the die, and cosintering to produce the die, the layers being arranged to provide a toughness and a hardness gradient in the die.

5 Claims, 7 Drawing Figures ROCKWELL c" HARDNESS Pmmen z 7 3,793.91 1

I saw 1 BF 2 HARDNESS ROCKWELL C HARDNESS TOUGHNESS ROCKWELL c" HARDNESS EXTRUSION DIE AND METHOD FOR MAKING THE SAME.

This is a division of application Ser. No. 150,496 filed June 7, 1971.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved extrusion die and to methods for making the same.

2. Description of the Prior Art Extrusion dies used, for example, in the hydrostatic extrusion of rod to produce wire, conventionally embody a generally physically homogeneous structure, no provision being made to provide the die with a profile of physical properties (compressive strength to hardness, toughness or ductility) tailored to meet the particular stresses imposed upon various portions of the die.

Consequently, such extrusion dies represent a compromise in design and are not entirely satisfactorily in operation, or the dies are overdesigned, and hence expensive, in order to provide satisfactory operating characteristics.

The present invention provides an extrusion die having high compressive strength or hardness at the throat end and a high degree of toughness at the entrance end. The present invention also provides novel methods of making such an improved extension die, whereby to overcome deficiencies noted in conventional extrusion dies.

SUMMARY OF THE INVENTION One of the objects of this invention is to provide an improved extrusion die.

Another of the objects of this invention is to provide novel methods for making an improved extrusion die.

Still another object of this invention is to provide an improved extrusion die of particular utility and efficiency in continuous hydrostatic extrusion of rod to produce wire.

Yet a further object of this invention is to provide an extrusion die in which, in a broad sense, hardness and toughness vary longitudinally in the die body between the entrance end and the throat end, i.e., the die has a toughness gradient increasing toward the entrance end and a hardness gradient increasing toward the throat end.

Another object of this invention is to provide an improved extrusion die having a profile of physical properties (e.g., toughness, hardness) tailored to meet particular stresses imposed upon various portions of the die.

Yet a further object of this invention is to provide an improved extrusion die having high compressive strength'or hardness at the throat end of the die, and having a large degree of toughness at the entrance end of the die.

Still other and further objects of this invention will become apparent during the course of the following description and by reference to the accompanying drawings and the appended claims.

Briefly, we have discovered that the foregoing objects may be attained by forming an extrusion die from a billet of material having toughness increasing from one end to the other and hardness increasing in the opposite direction so that the die, when formed, has greatest toughness at the entrance end thereof and greatest hardness at the throat end thereof.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings in which like numerals represent like parts in the several views:

FIG. 1 represents a medial longitudinal section of a representative apparatus for hydrostatic extrusion, showing a rod being extruded through a conventional die to produce wire.

FIG. 2 represents a medial longitudinal section through the improved die of the present invention, the distribution of toughness and hardness (i.e., the toughness gradient and the hardness gradient) along the die being indicated diagrammatically to one side of the die, and an illustrative distribution of hardness values likewise being indicated diagrammatically to one side of the die.

FIG. 3 represents diagrammatically a view of a conical billet of work hardenable material, shown in solid lines, being subjected to forces of compression, shown by the arrows, and strained to produce a rectangular billet, shown in phantom outline, an illustrative distribution of hardness values in the thus-non-uniformly worked rectangular billet being indicated diagrammatically, the die to be produced from the rectangular billet and its orientation with respect thereto being indi cated in dotted outline, said die corresponding with the die shown in FIG. 2.

FIG. 4 represents diagrammatically a view of a billet of heat treatable material being end-quenched to achieve a distribution of hardness values indicated by way of illustration in the figure, the die to be produced from the end-quenched billet and its orientation with respect thereto being indicated in dotted outline, said die corresponding with the die shown in FIG. 2.

FIG. 5 represents diagrammatically a view of a billet of cosintered powder materials of different postsintering hardness and toughness characteristics having a distribution of hardness values as shown illustratively in the figure, the die to be produced from the sintered billet and its orientation with respect thereto being indicated in dotted outline, said die corresponding with the die shown in FIG. 2.

FIG. 6 represents diagrammatically a view of a billet of elements having different hardness and toughness characteristics secured, as by brazing, to each other, a distribution of hardness values being shown illustratively in the figure, the die to be produced from the composite billet and its orientation with respect thereto being indicated in dotted outline, said die corresponding with the die shown in FIG. 2.

FIG. 7 represents a vertical medial section of molds forming and compacting layers of cosinterable powder 7 materials of different post-sintering hardness and toughness characteristics in the form of the die shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Representative apparatus for the hydrostatic extrusion of rod 1 to produce wire 2 is shown in FIG. 1 as comprising chamber 3 receiving the said rod 1 and conventional extrusion die 4 supported within the chamber 3 by means of die stem 5, the latter being provided with a longitudinal aperture 6 through which the extruded wire 2 passes. It will be understood that the effect of extrusion shock is greatest at the entrance end of the die, and longitudinal compression forces are at a maximum at the throat end of the die. Die 4 generally has uniform values of hardness and toughness longitudinally thereof, and therefore die 4 is either inadequately designed to resist extrusion shock which, as above mentioned, is greatest at the die entrance end, or is overdesigned to resist the longitudinal compression forces which are a maximum atthe throat end of the die.

An improved extrusion die 7 is shown in FIG. 2. Die 7 is provided with a longitudinal toughness gradient and a longitudinal hardness gradient as indicated diagrammatically. Specifically, die 7 has the greatest toughness at the entrance end thereto, which toughness decreases toward the throat end of die 7. Conversely, die 7 has the greatest hardness or compressive strength at the throat end of the die which hardness or compressive strength decreases toward the entrance end thereof. More specifically, Rockwell C values 'of hardness are shown as ranging between a lower value of 50 at the entrance end to die 7 and an upper value of 65 at the throat end of die 7. it will be understood that these Rockwell C values of hardness are merely illustrative.

FIG. 3 illustrates one method of making die 7. A conical billet 6 of work-hardenable material (e.g., a workhardenable steel) is deformed, by compressive forces 9, to the cylindrically shaped billet shown in phantom lines, the material adjacent the upper surface of billet 10 having been strained and therefore work-hardened to a greater degree than the material adjacent the lower surface of billet 10, and the material between the upper and lower surfaces of billet 10 having been strained and therefore work-hardened to an intermediate degree. It will be seen, therefore, that because of the progressively greater working of the material of billet 10 from the bottom to the upper surface thereof, the hardness of billet 10 will increase from the bottom to theupper surface thereof, as indicated in the scale of Rockwell C hardness values shown in the figure (which values are illustrative only). It will, of course, be understood that the initial hardness of the material constituting billet 8, and the configuration of billet 8 relative to billet 10, will be so chosen as to produce a-billet 10 having the desired range of Rockwell C values.

After billet 10 with the said desired range of Rockwell C values has been produced by the method hereinbefore described, die 7 can be cut from billet 10 as shown.

FIG. 4 illustrates another method of making die 7. A billet ll of heat-treatable material (e.g., heat treatable steel), after having been elevated to the proper prequenching temperature for heat treating, is quenched at one end only. The effect of this end quenching will be greatest at the top surface of billet 11 and will decrease toward the bottom surface of billet 11. It will be seen therefore that the hardness of billet 11 will decrease from the top surface of billet 11 toward the bottom surface thereof, as indicated on the scale of Rockwell C hardness values shown in the figure (which values are illustrative only).

After billet 11 with the desired range of Rockwell C" values has been produced by the end-quenching method hereinabove described, die 7 can be cut from billet 11 as shown.

FIG. 5 illustrates yet another method of making die 7. A plurality of layers 12 of compatible sinterable powder materials having different post-sintering characteristics of hardness and toughness is arranged so that, after firing and cosintering the said' layers 12, a composite billet 13 is produced having toughness increasing from one end to the other and hardness increasing in the opposite direction, as indicated on the scale of Rockwell C hardness values (which values are illustrative only).

After composite billet 13 with the desired range of Rockwell C hardness values has been produced, die 7 can be cut from composite billet 13 as shown.

FIG. 6 illustrates still another method of making die 7. A plurality of elements 14 of varying toughness and hardness is arranged and assembled, and the elements 14 brazed to each other to form a composite billet 15 having toughness increasing from one end to the other and hardness increasing in the opposite direction, as indicated on the scale of Rockwell C hardness values (which values are illustrative only).

After composite billet 15 with the desired range of Rockwell C hardness values has been produced, die 7 can be cut from composite billet 15 as shown.

FIG. 7 illustrates another method of making a die 7 I of cosintered powder materials, and is an alternate to the method demonstrated in FIG. 5. Mold l6,'having a profile corresponding with the inner surface of die 7, i.e., the surface converging from the entrance to the throat of the die 7 and the land through the die throat, is placed in barrel l7, and layers 18 of sinterable powder materials having different post-sintering characteristics of toughness and hardness are formed in barrel 17 over mold 16, the said layers 18 being so arranged that, after mold 19 is introduced into barrel l7 and forced downwardly to mold and compact the said powder materials, and after the molded and compacted powder materials have been removed from barrel 17 and tired to cosinter the same, die 7 resulting from the firing operation will have toughness increasing from the throat to the entrance thereof and hardness increasing in the opposite direction, with the desired range of hardness values shown for illustrative purposes in the other figures.

What is claimed is:

1. Method of making a die having an entrance end adapted to receive a workpiece and a throat end downstream of said entrance end, said method comprising:

a. applying force to a billet of work-hardenable material to differentially change the cross-sectional area of said billet from one end thereof toward an opposite end thereof thereby differentially deforming said billet to produce a deformed billet having a predetermined hardness gradient increasing from said one end toward said opposite end of said deformed billet,

b. forming a die from said deformed billet with the entrance end to the die formed from that portion of said deformed billet having lower hardness and the throat end of the die formed from that portion of said deformed billet having greater hardness.

2. Method of making a die having an entrance end adapted to receive a workpiece and a throat end downstream of said entrance end, said method comprising:

a. forming a conical billet of work-hardenable material with a predetermined profile;

b. applying force to opposite ends of said conical billet parallel to the altitude thereof sufficient to compress and deform said billet, thereby to foreshorten d. step (a) is performed by forming a truncated conical billet.

4. Method as in claim 2, wherein:

e. step (b) is performed by deforming said conical billet to a rectangular shape.

5. Method as in claim 2, wherein:

d. performing step (c) by forming said die with its longitudinal axis registering with the original altitude of the billet.

L-566-PT UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 'PatenrNo. 3,793,911 I Dated February 97M Inventor-FRANCIS JOSEPH FUCHS, J'R.; PERUVEMBA SWAMINATHA VENKATESAN It is certified that error appears in the above-identified parent and that said Letters Patent are hereby corrected as shown below:

IN THE SPECIFICATION: I

Column 1, line 16, "to" should read --or--; line 20 "satisfactorily should read "satisfactory"; line 28 "extension" should read --extrusion.

Column 3, line 26, billet 6" should read billet 8--.

Signed and sealed this 11th day of June 197L|.. v

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer C. MARSHALL DANN Commissioner of Patents

Claims

1. Method of making a die having an entrance end adapted to receive a workpiece and a throat end downstream of said entrance end, said method comprising: a. applying force to a billet of work-hardenable material to differentially change the cross-sectional area of said billet from one end thereof toward an opposite end thereof thereby differentially deforming said billet to produce a deformed billet having a predetermined hardness gradient increasing from said one end toward said opposite end of said deformed billet, b. forming a die from said deformed billet with the entrance end to the die formed from that portion of said deformed billet having lower hardness and the throat end of the die formed from that portion of said deformed billet having greater hardness.

2. Method of making a die having an entrance end adapted to receive a workpiece and a throat end downstream of said entrance end, said method comprising: a. forming a conical billet of work-hardenable material with a predetermined profile; b. applying force to opposite ends of said conical billet parallel to the altitude thereof sufficient to compress and deform said billet, thereby to foreshorten the altitude of said billet and to differentially increase the transverse cross-sectional area to a predetermined degree, whereby to differentially work-harden the billet in a direction parallel to the altitude thereof; c. forming said die from said billet, the longitudinal axis of said die being parallel to the altitude of said billet, the entrance end to said die facing the base of said billet.

3. Method as in claim 2, wherein: d. step (a) is performed by forming a truncated conical billet.

4. Method as in claim 2, wherein: e. step (b) is performed by deforming said conical billet to a rectangular shape.

5. Method as in claim 2, wherein: d. performing step (c) by forming said die with its longitudinal axis registering with the original altitude of the billet.