US3766769A

US3766769A - Method of and means for commencing a deforming operation, e. g., hydrostatic extrusion of a billet

Info

Publication number: US3766769A
Application number: US00266143A
Authority: US
Inventors: F Fuchs; Venkatesan P Swaminatha
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1972-06-22
Filing date: 1972-06-22
Publication date: 1973-10-23
Anticipated expiration: 1990-10-23
Also published as: CA968747A

Abstract

A billet nose is prepared by superposing layers of sinterable powders in a billet nose mold, the layers having different postsintering hardness characteristics and being arranged in order of said post-sintering hardness characteristics, compacting the superposed layers and then cofiring the mass of compacted layers to produce a sintered billet nose having a hardness gradient increasing from the forward end to the rearward end thereof. The rearward end of the sintered billet nose is mounted to the forward end of the main billet and deformation thereof is commenced.

Description

United States Patent 1 Fuchs, Jr. et a1.

[ Oct. 23, 1973 METHOD OF AND MEANS FOR COMMENCING A DEFORMING OPERATION, E. G., HYDROSTATIC EXTRUSION OF A BILLET [75] Inventors: Francis Joseph Fuchs, Jr., Princeton Junction; Peruvemba Swaminatha Venkatesan, Princeton, both of NJ.

[73] Assignee: Western Electric Company,

Incorporated, New York, N.Y.

22 Filed: June 22,1972

211 Appl. No.: 266,143

[52] U.S. Cl 72/256, 29/182.2, 29/187.5 [51] Int. Cl. B2lc 5/00 [58] Field of Search 72/60, 253, 256;

[56] References Cited UNlTED STATES PATENTS Buffet et a1. 72/256 Schreiner 29/1 82.2 Nilsson 29/l87.5

liig ry ExaminerRichard J. Herbst Attorney-Jack Schuman [57] ABSTRACT A billet nose is prepared by superposing layers of sinterable powders in a billet nose mold, the layers having different post-sintering hardness characteristics and being arranged in order of said post-sintering hardness characteristics, compacting the superposed layers and then cofiri ng the mass of compacted layers to produce a sintered billet nose having a hardness gradient increasing from the forward end to the rearward end thereof. The rearward end of the sintered billet nose is mounted to the forward end of the main billet and deformation thereof is commenced.

13 Claims, 4 Drawing Figures PATENTEDUCI23 I975 SHEET 10F 2 *mmnwwmmm Q D E hmOuEm TIME PATENHUUBTB I975 3.766769 SHEET 2 [IF 2 6 W HIE METHOD OF AND MEANS FOR COMMENCING A DEFORMING OPERATION, E. G., I-IYDROSTATIC EXTRUSION OF A BILLET BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, generally speaking, to improved method of and means for commencing an extrusion or drawing operation. Specifically, this invention relates to method and means for eliminating or substantially reducing peak effort ordinarily required to initiate an extrusion or drawing operation. More specifically, this invention relates to method of and means for eliminating or substantially reducing peak pressure heretofore encountered in commencing hydrostatic extrusion.

2. Description of the Prior Art Various methods and means for drawing or extrusion, including hydrostatic extrusion, are now well known. See, for example, U. S. Pat. No. 3,667,267 which teaches method and apparatus for continuously hydrostatically extruding an elongated billet of indefinite length to produce wire of indefinite length.

In commencing hydrostatic extrusion of certain materials to obtain certain ratios of reduction, it has been noted that, when the nose of the billet enters and initially contacts the zone of deformation of the die, the pressure of the extrusion fluid rises to a peak value until extrusion commences. After extrusion commences, the pressure of the extrusion fluid falls to a lower, substantially constant, level known as the run-out" pressure.

Although the peak pressure occurs only at the commencement of an extrusion operation, the pressure vessel for containing the extrusion operation, the die, die stem and related components must be designed to withstand this peak pressure which may, in some instances, be as much as 25 percent or more above run-out pressure, even though virtually the entire extrusion operation is performed at the lower run-out pressure. Thus, for virtually the entire extrusion operation, the pressure vessel, die, die stem and related components are overdesigned by as much as 25 percent or more.

From another point of view, the phenomenon of peak pressure may inhibit the degree of reduction obtainable by equipment of a given design. Elimination or substantial reduction of peak pressure permits much higher (e.g., by an order of magnitude or so) ratios of reduction in equipment of a given design and pressure capability. Indeed, for certain materials, ratios of reduction are now attainable which heretofore were not attainable because of design limits on maximum pressure of equipment.

An example of the relationship between peak pressure and run-out pressure can be seen in the hydrostatic extrusion of a 0.300 inch diameter copper billet to produce 0.0l3 inch diameter wire, representing a reduction ratio of 500, wherein the peak pressure in the extrusion fluid is 370,000 psi and the run-out pressure in the extrusion fluid is 280,000 psi.

Moreover, as peak pressure is reached, extrusion commences with a burst of speed, which may be undesirable.

In non-hydrostatic extrusion operations, and also in drawing operations, it has been noted that, for certain materials and for certain ratios of reduction, the initial effort required to commence the extrusion or drawing operation is substantially in excess of the efiort required to maintain the extrusion or drawing operation and, further, with conventional billets, the extrusion or drawing operation may commence with an undesirable burst of speed.

Efforts have been made in the past to .facilitate the extrusion of billets. In U. S. Pat. No. 2,630,220 (1953) to Sejournet, extrusion of a hot billet or ingot of steel is commenced by interposing between the front end of the hot billet and the die a packet of glass fibers and glass plate, the glass melting under the heat of the billet and lubricating the die. In U. S. Pat. No. 3,345,842 (1967) to Richards, a hot billet is coated with a plurality of layers of glass of different viscosity-temperature characteristics (e.g., by sequentially dipping the entire hot billet into tanks of the various molten glasses) and is then extruded through a die.

In each of the above instances, the molten glass acts as a lubricant.

SUMMARY OF THE INVENTION One of the objects of this invention is to provide improved method of and means for commencing an extrusion or a drawing operation. 7

Another of the objects of this invention is to provide improved method of and means for eliminating or substantially reducing peak effort ordinarily required to initiate an extrusion or drawing operation.

Still another of the objects of this invention is to pro vide improved method of and means for commencing a hydrostatic extrusion operation.

Yet another of the objects of this invention is to provide method of and means for eliminating or substantially reducing peak pressure in hydrostatic extrusion.

A further object of this invention is to provide method of and means for smoothly commencing hydrostatic extrusion.

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 appended claims.

Briefly, we have discovered that the foregoing objects may be attained by superposing layers of sinterable powders in a billet nose mold, the layers having diffrent post-sintering hardness characteristics and being arranged in order of said post-sintering hardnesscharacteristics, compacting the superposed layers and then cofiring the mass of compacted layers to produce a sintered billet nose having a hardness gradient increasing from the forward end to the rearward end-thereof. The rearward end of the sintered billet nose is mounted to the forward end of the main billet and deformation thereof is commenced.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings, in which like numerals represent like parts in the several viewsz FIG. 1 represents an idealized plot of deformation effort (e.g., extrusion fluid pressure) vs. time for two conditions, viz., deformation with an ordinary billet and deformation with a billet provided with a billet nose prepared according to the present invention.

FIG. 2 represents a view in section of a billet nose FIG. 4 represents a medial longitudinal section of hydrostatic extrusion apparatus as disclosed in U. S. Pat. No. 3,667,267 and shows a billet having a billet nose, which has just engaged the zone of deformation of the die and which has not yet commenced to extrude.

DESCRIPTION OF THE PREFERRED EMBODIMENT In commencing the hydrostatic extrusion of conventional billets (e.g., rods of indefinite length) of certain materials to achieve certain ratios of reduction, when the nose of the billet enters and initially contacts the zone of deformation of the die, and until extrusion of the billet through the die commences, the pressure of the extrusion fluid rises generally along curve 1 of FIG. 1 and reaches a maximum value 2. When the billet begins to extrude through the die, the pressure of the extrusion fluid decreases, generally along curve 3, to a lower substantially constant level 4 known as the runout" pressure.

The difference between the maximum or peak pressure 2 and the run-out pressure 4 requires that the pressure vessel for containing the extrusion operation, the die, die stem and related components be overdesigned for this high transitory condition.

The present invention eliminates or substantially reduces this peak or maximum pressure 2, and permits the extrusion apparatus to be designed to operate substantially under the conditions of run-out pressure.

Billet nose mold 5 has aperture 6 therein, the bottom of which is closed by plug 7. The cross section of aperture 6 corresponds to the cross section of the desired billet nose 8.

In preparing billet nose 8, layers 9a 9n of sinterable powders of different post-sintering hardness characteristics are deposited within aperture 6 over plug 7. Layers 9a 9n are arranged in order of their postsintering hardness characteristics, e.g., layer 9a when sintered is softer than layer 9b when sintered, and so on, layer 9n being the hardest of all of the said layers 9a 9n when sintered. The hardness of layer 9n when sintered may be equal to or less than, but not greater than, the hardness of main billet l0.

Layers 9a 9n may be prepared from suitable sinterable metallic materials or mixtures thereof in varying proportions, such as mixtures of lead and copper, the weight percentages of lead and copper in the several layers 9a 9n being varied in order to provide the several said layers with the desired hardnesses.

Thereafter, ram 10 is forced into aperture 6 by suitable means (not shown, but indicated schematically by the arrow in FIG. 2), against the top of layer 9n thereby to compact the several layers 9a 9n into a green billet nose ll. Compacted green billet nose 11 is now removed from aperture 6 of billet nose mold 5 (e.g., by removing plug 7 and advancing ram 10 to force the green billet nose 11 out of aperture 6).

Green billet nose I1 is then sintered by techniques known in the art to produce sintered billet nose 8.

A male conical forward end I2 is provided on billet nose 8 after the sintering operation. Alternatively, green billet 11 may be provided with male conical forward end 12 before the sintering operation.

Billet nose 8,prepared in the manner hereinabove described is mounted in a suitable manner (e.g., by welding) to the forward end of main billet 13.

Main billet 13, having billet nose 8 fastened thereto, is shown in FIG. 4, prior to the actual commencement of extrusion and at the point of initial contact with the zone of deformation of die 14 of extrusion apparatus 15 of the type described in U. S. Pat. No. 3,667,267. Male conical forward end 12 of billet nose 8 corresponds in profile to the profile of die 14. Extrusion apparatus 15 forms no part of the present invention and reference to U. S. Pat. No. 3,667,267 should be made if a detailed description of the construction and operation of the said extrusion apparatus 15 is desired.

When hydrostatically extruding main billet 13 with billet nose 8, the pressure of the extrusion fluid rises generally along curve 1 of FIG. 1 until extrusion of billet nose 8 commences and thence along curve 16 until extrusion of main billet 13 commences and thence along curve 4.

In the foregoing description, the value of the present invention has been illustrated in a hydrostatic extrusion environment. The present invention is capable of reducing the effort required to initiate non-hydrostatic extrusion and drawing operations smoothly and without initial peaks in the effort required for such operations.

What is claimed is:

l. A billet comprising:

a. a main body portion having a forward end;

b. a billet nose having a rearward end and a forward end and an axis runnning therebetween, the rearward end of said billet nose being mounted to the forward end of said main body portion;

. said billet nose comprising a plurality of layers of sintered materials disposed transversely to said axis and having different hardnesses, the said layers of sintered materials being arranged in order of said hardnesses so as to provide said billet nose with a hardness gradient increasing from the forward end toward the rearward end thereof, the hardness of the rearward end of said billet nose not exceeding the hardness of said main body portion.

2. A billet as in claim 1 wherein the rearward end of said billet nose is welded to the forward end of said main body portion.

3. A billet as in claim 1 wherein said materials are metallic.

4. A billet as in claim 1 wherein said layers of materials comprise mixtures of copper and lead in varying proportions.

5. Means for facilitating the commencement of deformation against a deforming agency of a billet having a forward end, said means comprising:

a. a billet nose having a rearward end and a forward end and an axis running therebetween;

b. the rearward end of said billet nose being adapted to be mounted to the forward end of said billet;

said billet nose comprising a plurality of layers of sintered materials disposed transversely to said axis and having different hardnesses, the said layers of sintered materials being arranged in order of said hardnesses so as to provide said billet nose with a hardness gradient increasing from the forward end to the rearward end thereof, the hardness of the rearward end of said billet nose not exceeding the hardness of said billet.

6. Means as in claim 5 wherein the rearward end of said billet nose is adapted to be welded to the forward end of said billet.

7. Means as in claim 5 wherein said materials are metallic.

8. Means as in claim 5 wherein said layers of materials comprise mixtures of copper and lead in varyinv proportions.

9. Method of commencing deformation against a deforming agency of a billet having a forward end, said method comprising:

a. arranging and compacting a plurality of bodies of sinterable materials having different post-sintering hardnesses, ranging up to a post-sintering hardness not in excess of the hardness of said billet, in order of said post-sintering hardnesses to form an unsintered billet nose having a forward end and a rearward end with the body of that material having the lowest post-sintering hardness at the forward end of said unsintered billet nose and with the body of that material having the highest post-sintering hardness at the rearward end of said unsintered billet nose;

b. sintering said unsintered billet nose to form a sintered billet nose;

c. securing the rearward end of said sintered billet nose to the forward end of said billet;

d. advancing said billet and said sintered billet nose against the deforming agency to deform the sintered billet nose and then the billet.

10. Method as in claim 9, wherein the rearward end of the sintered billet nose is welded to the forward end of said billet.

11. Method as in claim 9, wherein the hardness of the rearward end of said sintered billet nose is equal to the hardness of said billet.

12. Method of preparing a billet nose adapted to be mounted to the forward end of a billet to facilitate deformation thereof, said method comprising:

a. arranging and compacting a plurality of bodies of sinterable materials having different post-sintering hardnesses ranging up to a post-sintering hardness not in excess of the hardness of said billet, in order of said post-sintering hardnesses to form an unsintered billet nose having a forward end and a rearward end with the body of that material having the lowest post-sintering hardness at the forward end of said unsintered billet nose and with the body of that material having the highest post-sintering hardness at the rearward end of said billet nose;

b. sintering said unsintered billet nose to form a sintered billet nose.

13. Method as in claim 12 wherein the hardness of the rearward end of the sintered billet nose is equal to the hardness of said billet.

Claims

1. A billet comprising: a. a main body portion having a forward end; b. a billet nose having a rearward end and a forward end and an axis running therebetween, the rearward end of said billet nose being mounted to the forward end of said main body portion; c. said billet nose comprising a plurality of layers of sintered materials disposed transversely to said axis and having different hardnesses, the said layers of sintered materials being arranged in order of said hardnesses so as to provide said billet nose with a hardness gradient increasing from the forward end toward the rearward end thereof, the hardness of the rearward end of said billet nose not exceeding the hardness of said main body portion.

3. A billet as in claim 1 wherein said materials are metallic.

5. Means for facilitating the commencement of deformation against a deforming agency of a billet having a forward end, said means comprising: a. a billet nose having a rearward end and a forward end and an axis running therebetween; b. the rearward end of said billet nose being adapted to be mounted to the forward end of said billet; c. said billet nose comprising a plurality of layers of sintered materials disposed transversely to said axis and having different hardnesses, the said layers of sintered materials being arranged in order of said hardnesses so as to provide said billet nose with a hardness gradient increasing from the forward end to the rearward end thereof, the hardness of the rearward end of said billet nose not exceeding the hardness of said billet.

7. Means as in claim 5 wherein said materials are metallic.

8. Means as in claim 5 wherein said layers of materials comprise mixtures of copper and lead in varying proportions.

9. Method of commencing deformation against a deforming agency of a billet having a forward end, said method comprising: a. arranging and compacting a plurality of bodies of sinterable materials having different post-sintering hardnesses, ranging up to a post-sintering hardness not in excess of the hardness of said billet, in order of said post-sintering hardnesses to form an unsintered billet nose having a forward end and a rearward end with the body of that material having the lowest post-sintering hardness at the forward end of said unsintered billet nose and with the body of that material having the highest post-sintering hardness at the rearward end of said unsintered billet nose; b. sintering said unsintered billet nose to form a sintered billet nose; c. securing the rearward end of said sintered billet nose to the forward end of said billet; d. advancing said billet and said sintered billet nose against the deforming agency to deform the sintered billet nose and then the billet.

12. Method of preparing a billet nose adapted to be mounted to the forward end of a billet to facilitate deformation thereof, said method comprising: a. arranGing and compacting a plurality of bodies of sinterable materials having different post-sintering hardnesses, ranging up to a post-sintering hardness not in excess of the hardness of said billet, in order of said post-sintering hardnesses to form an unsintered billet nose having a forward end and a rearward end with the body of that material having the lowest post-sintering hardness at the forward end of said unsintered billet nose and with the body of that material having the highest post-sintering hardness at the rearward end of said billet nose; b. sintering said unsintered billet nose to form a sintered billet nose.