US3577761A

US3577761A - Method of manufacturing components from a part projecting from a larger part, having slim and/or elongated form

Info

Publication number: US3577761A
Application number: US711829A
Authority: US
Inventors: Eskil Monestam
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1967-03-07
Filing date: 1968-03-04
Publication date: 1971-05-04
Anticipated expiration: 1988-05-04
Also published as: JPS493394B1; GB1209200A; SE353029B; FR1555351A

Abstract

In the manufacture of objects or components with one part having larger dimensions and one part having slim and/or elongated form, a billet is used which in a first step is forged, preferably cold-forged to a blank with decreasing cross section. This blank is thereafter, possibly after annealing and machining, extruded by means of liquid pressure to the desired shape and dimension at the narrow end of the blank.

Description

United States Patent Inventor Eskil Monestam Umea, Sweden Appl. No. 711,829 Filed Mar. 4, 1968 Patented May 11, 1971 Assignee Allmanna Svenska Elektriska Aktiebolaget Vasteras, Sweden Priority Mar. 7, 1967 Sweden 3082/67 METHOD OF MANUFACTURING COMPONENTS FROM A PART PROJECTING FROM A LARGER PART, HAVING SLIM AND/OR ELONGATED FORM 2 Claims, 4 Drawing Figs.

US. Cl 72/256, 72/260, 72/60 Int Cl B2lc 23/00 Field of Search 72/256, 260, 60

References Cited UNITED STATES PATENTS 4/1921 l-Iuntoon 4/1921 Huntoon 8/1968 Fuchs 6/1969 Sauve 6/1951 Bridgman FOREIGN PATENTS I 1/1964 France Primary ExaminerCharles W. Lanham Assistant Examiner-Michael J. Keenan Attorney-Jennings Bailey, Jr.

ABSTRACT: In the manufacture of objects or components with one part having larger dimensions and one part having slim and/or elongated form, a billet is used which in a first step is forged, preferably cold-forged to a blank with decreasing cross section. This blank is thereafter, possibly after annealing and machining, extruded by means of liquid pressure to the desired shape and dimension at the narrow end of the blank.

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METHOD or MANUFACTURING COMPONENTS FROM A PART PRoJEcTINc FROM A LARGER PART, HAVING SLIM AND/R ELONGATED roRM BACKGROUND or THE INVENTION 1. Field of the Invention Thepresent invention relates to amethod of manufacturing components from a part projecting from a larger part, having slim and/or elongated form.

2. The Prior Art 7 g A conventional shaping method for metal objects is coldforging. This method is, in suitable cases, particularly favorable in comparison with hot-forging, as it eliminates the necessity of heating and the removal of oxides and remaining lubricant after processing. With cold-forging greater accuracy in measurement is obtained and smoother surfaces of the coinponents and often the need is eliminated for subsequent treatment with a cutting tool, which thus also decreases the 'material losses. The treated product also obtains improved internal properties in comparison with hot-forged products, for example increased strength due to the deformation hardening which takes place when the object is molded at a temperature below the recrystallization temperature. Cold-forged components are shaped from the billet under extremely high pressure against and through a die from a forging punch, after which the punch is drawn back and the body thus formed is expelled from the die.

In so-called rod extrusion a punch having at least the same area as the billet presses a billet down through a die at its lower end and a solid rod-shaped body is obtained. In tube-extrusion a billet is used having a hole in the center into which a mandrel is insetted, but otherwise the method is the same. A cup-shaped body is obtained by cup-extrusion, a process similar to cold-forging. v 1

The high pressures required for cold-forging are obtained in special hydraulic high pressure presses with a stand, for example according to Swedish Pat. No. l86,278,'provided'with two.

semicircular prismatic yokes which are held apart by two parallel-epipedic bodies. The yokes and bodies are kept together by a sheath of several layers 'of steel wire in order to obtain a prestressing to absorb the pressure forces.

Components with considerable differences in area must, however, usually be forged in several stages since otherwise the strain on the tools would be too great. Parts'of a billet formed in earlier stages must in certain cases be supported so that they are not deformed in later stages in the forging and this has limited the practicality of cold-forging.

Tubeand rod-shaped bodies with even and normally narrow section have been manufactured by extrusion ortube-extrusion, often in cold state. In this case use is made 'of the fact that a high hydrostatic pressure increases the plastic moldability of otherwise relatively brittle materials. A billet is pressed by means of very high hydrostatic pressure through a nozzle and, when the pressure is sufficiently high, the components are expelled. Also in this case a high pressure press is used to obtain the pressure, which has a punch which is pushed into an enclosed volume of liquid and thus effects the high pressure. I

Such extrusion has been proposed for bodies having more complicated shapes, wherein 00 in a first extrusion stage a certain preshaping is obtained after which the preshaped billet is turned and the preshaped part further extruded to the finally desired form, for example conical or with successively-changing cross section. This last-mentioned method is relatively complicated and needs an extremely advanced type of tool.

SUMMARY or THE INVENTION The invention relates to a method in which the advantages of the forging and extrusion methods are exploited butwhere at the same time the disadvantagesareavoideek l he method is characterized in that a billet is first forged in khown manner,

ing, is extruded by means of liquid pressure to the desired shape and dimension at the narrow end of the billet. In this way the need is eliminated for special tools for support when cold-forging slim or elongated sections and for more complicated multistage operations for extrusion.

BRIEF DESCRIPTION OF THE DRAWING IiES'CRlITION OF THE PREFERRED EMBODIMENTS A billet ll of metal, for example soft carbon steel, is placed on a pressure surface (die) or cushion 12 in a pressure cylinder 13 and a forging punch 14 with central mandrel 15 presses the billet 11 with considerable force against the surface 12 so that the billet is cold-forged to an intermediate shape according to FIG. 2. The cold-pressure during the forging operation (tube-extrusion) is maintained at about l520 kbar 20,000 leg/cm. and the operation may be carried out in a high pressure press of the type described above.

The billet thus formed can also be obtained through hotfo'rging, but certain disadvantages arise which have been indicated above. It is also possible to subject the billet 11 to certain cutting processes.

Cold-forging according to the above may also be carried out for other types of components, for example in the form of cupext'rusion or rod-extrusion, so as to obtain hollow objects with bottoms or solid objects.

The billet 11 obtained by forging is placed in a pressure chamber (FIGS. 3 and 4). In the pressure chamber are also piston 19, the pressure is increased in this to a level for extrusion of the narrower section of the billet (see 20 in FIG. 4).

In the case shown the billet has a diameter of about 100 mm at its upper, supported part and a cross section of 8000mm? The extruded part which cannot be forged has 1/100 of these dimensions. A pressure of IS kbar is obtained in this way, for example in a pres's'according to the above, and the unsupported, narrower part of the billet is pressed out between the die 18 and the mandrel 17 and ap'rojecting part having slim dimension is obtained from an otherwise larger component. If desired, this component may afterwards be flattened by drawing in a drawing die, rolling, or the like.

The method is not limited to components which are tubeextruded' in the first stage. Rod and cup extruded components with decreasing section and a part with slim and/or elongated 1 form can also be extruded in this way. In this case the central for example cold-forged with decreasing section, after which the billet thus obtained, possibly after annealing and machinmandrel is omitted. As mentioned, the stop may besituated before the component.

when the pressure is increased to extrusion level by pressing in the extrusion punch 14 in the oil chamber, the plastic-mouldability of the billet 11 is increased and the billet is subjected to hydrostatic pressure all over except on the side where the billet is in contact with the die 18 at the mandrel 17 (21). The material is extruded at asufficiently high pressure into the annular passage and an annular, cylindrical (or otherwise-shaped) part 20 of the billet is obtained with slim and elongated dimension. Such a component could not, without considerable difficulty, be manufactured solely through forging in several stages.

After cold-forging and/or after extrusion the billet can be annealed,su i tably a protective atmosphere.

The method can be varied in many ways within the scope of the following claims.

lclaim:

14 A method for extruding a member having a first portion of larger diameter with upper and lower faces and a second portion of less diameter protruding below the lower face, which comprises positioning said member in a high pressure cylinder having a main portion with a cross section of greater area than the cross section of said first portion, said cylinder having a top wall and having a bottom wall with means therein forming a die opening of substantially the same shape as said second portion with said second portion aligned with and adjacent the entrance of said die opening and said upper and lower faces of the first portion spaced from the top and bottom walls, said cylinder having a fluid therein surrounding said first portion on both faces thereof, and applying pressure to said fluid sufficient to cause said second portion to be exface, which comprises positioning said member in a high pressure cylinder having a top wall and having a bottom wall with an opening therein and a mandrel in said opening forming therewith an annular die opening of substantially the same shape as said protruding portion, with said first portion resting on said bottom wall, said cylinder having fluid therein engaging the upper face of said first portion, and'applying pressure to said fluid sufficient to cause said second portion to be extruded through said opening.

Claims

1. A method for extruding a member having a first portion of larger diameter with upper and lower faces and a second portion of less diameter protruding below the lower face, which comprises positioning said member in a high pressure cylinder having a main portion with a cross section of greater area than the cross section of said first portion, said cylinder having a top wall and having a bottom wall with means therein forming a die opening of substantially the same shape as said second portion with said second portion aligned with and adjacent the entrance of said die opening and said upper and lower faces of the first portion spaced from the top and bottom walls, said cylinder having a fluid therein surrounding said first portion on both faces thereof, and applying pressure to said fluid sufficient to cause said second portion to be extruded through said die opening while remaining in engagement with the whole surface of said die opening forming means.

2. A method for extruding a member having a first portion of larger diameter with upper and lower faces and a second tubular portion of less diameter protruding below the lower face, which comprises positioning said member in a high pressure cylinder having a top wall and having a bottom wall with an opening therein and a mandrel in said opening forming therewith an annular die opening of substantially the same shape as said protruding portion, with said first portion resting on said bottom wall, said cylinder having fluid therein engaging the upper face of said first portion, and applying pressure to said fluid sufficient to cause said second portion to be extruded through said opening.