US3727253A

US3727253A - Process and an equipment for the plastic forming or shaping and simultaneous chip-free chopping of metal bars and wires

Info

Publication number: US3727253A
Application number: US00236762A
Authority: US
Inventors: J Burany; A Vollak; J Erdosi; J Nemeth; I Vas; E Csovak; G Gulyas
Original assignee: Koho es Gepipari Miniszterium
Current assignee: Gepipari Technologiai Intezet; Koho es Gepipari Miniszterium
Priority date: 1972-03-21
Filing date: 1972-03-21
Publication date: 1973-04-17
Anticipated expiration: 1990-04-17

Abstract

In a process and an apparatus for shearing metal bars under pressure, this bar is at the same time formed by cold flow and the pressure necessary for flowing is used for the purpose of the said shearing too.

Description

United States Patent 1 Burany et a].

[ 1 PROCESS AND AN EQUIPMENT FOR THE PLASTIC FORMING OR SHAPING AND SIMULTANEOUS CHIP-FREE CHOPPING OF METAL BARS AND WIRES [75] Inventors: Janos Biirany; Erno Csoy ak; Gabor Gulyas; Jozsef Nemeth; Ivan Vas; Andor Vollak; Jozsef Erdosi, all of Budapest, Hungary [73] Assignee: Gepipari Technologiai Intezet, Budapest, Hungary [22] Filed: Mar. 21, 1972 [21] Appl. N0 236,762

Related US. Application Data [63] Continuation of Ser. No. 03,287, Jan. -16,- 1970,

abandoned.

[52] US. Cl. ..10/86 F, 72/332, 72/338 [51] Int. Cl ..B2ld 53/24, B2ld 28/00 [451 Apr. 17, 1973 [58] Field of Search ..10/25, 27, 27.1, 10/72, 76, 86, 86 F; 72/332, 334, 337, 338

[56] References Cited UNITED STATES PATENTS 756,141 3/1904 Renner .10/86 F 1,619,495 3/1927 Wilcox .....10/27 PH 1,929,164 10/1933 Eden ..10/86 F 2,077,519 4/1937 Prayer ..10/86 F 2,106,274 1/1938 Frayer et a1. ..10/86 F 3,651,683 3/1972 Liebergeld ..l0/86 F Primary Examiner-Richard J. Herbst Assistant Examiner-E. M. Combs Attorney-Irvin S. Thompson [5 7] ABSTRACT In a process and an apparatus for shearing metal bars under pressure, this bar is at the same time formed by cold flow and the pressure necessary for flowing is used for the purpose of the said shearing too.

2 Claims, 3 Drawing Figures PATENTEU APR 1 7 ma sum 2 [IF 2 PROCESS AND AN EQUIPMENT FOR THE PLASTIC FORMING OR SHAPING AND SIMULTANEOUS CHIP-FREE CHOPPING OF METAL BARS AND WIRES This is a continuation, of application Ser. No. 3,287, filed Jan. 16, 1970, now abandoned.

Various methods are known for the chip-free chopping of metal bars and wires by shearing and subsequent cold impact forming (plastic forming). It is the object of the present invention to improve such known methods by subjecting the .workpiece simultaneously i.e. in the same step with the chopping, to plastic formation, conveniently by means of flowing.

According to the invention this is performed with the aid of a mandrel which penetrates the interior of the metal bar or wire so as to produce a hollow body.

It is another object of the invention to produce by the same method compact profiled bodies. A combination, i.e. simultaneous execution of both types of forming operations constitutes a further object of the present invention.

When hollow bodies are produced with the method according to the invention, it becomes possible to manufacture punches disks, female nuts or the like articles, which up to now could only be manufactured by machining or punching. These conventional manufacturing methods were time consuming, and entailed large amounts of scrap. With the method according to the invention, however, wherein the inner cavity is formed by flowing (cold impact forming), and this is combined with chopping, where the ambiance of the shorn surface of the workpiece is brought into a condition of mechanical stress approximating the yield point, it becomes possible to manufacture in a quick and cheap manner with no scrap, compact profiled bodies as well as hollow bodies, or profiled hollow bodies, such as for example the semi-finished products for female nuts.

Thus the most important feature of the invention is the idea that the stress produced in the workpiece for plastic flowing is at the same time utilized for a chipfree'chopping of the said workpiece by shearing under compressive stress.

The invention is more particularly described below with reference to the accompanying drawing showing two preferred embodiments of the equipment serving to carry out the method according to the invention, in which FIG. 1 is a schematic sectional view of the principal part of the equipment and FIGS. 2 and 3 represent another embodiment of the equipment in two different working phases, also schematically.

In FIG. 1 a bar 4 passes through the bore of a fixed tool 2, said bore coinciding in size and shape with the profile of the bar. A movable tool 1 acts also as a die and has a bore coinciding in shape and size to the article to be produced, thus, the two bores are different in size as well as profile. The movable tool 1 is also suitable for guiding a mandrel 5, provided for cold flowing and the cavity of tool 1 serving that purpose catches the external diameter and shape of the mandrel.

Feed blocks 3 serve to advance the bar 4. When feed has advanced so far as to reach the position shown in the figure, that is, when the bar 4 bears on the cavity of the movable tool l,then the mandrel 5 carries out an opposed movement, i.e. it advances from right. to left according to the drawing, and thus penetrates into the interior of the bar 4. Accordingly, shaping begins, and that portion of the metal bar 4 which is now in the movable tool 1, fills up completely the cavity or bore of said tool. After this step has been completed, that is, when the mandrel has penetrated the bar so deeply as to fill up the cavity ofthe movable tool, this tool starts advancing, i.e. chopping by shearing begins, and is also completed in such a manner that the mandrel moves together with the movable tool. 7

In order to achieve the process described above, it is obviously necessary that the device actuating the mandrel 5 also participates in the movement carried out in order to achieve shearing. For this purpose a hydraulic device may be employed to press the mandrel into the metal bar, said hydraulic device being connected with the source of the hydraulic fluid by means of flexible hoses. In this case nothing prevents the mandrel and its actuating mechanism from moving together with the moving too]. Other embodiments can also be used, i.e. the mandrel 5 may be connected with the moving or ac tuating means with the aid of a lever system whichpermits motion perpendicular to the longitudinal axis. In another embodiment the extremity of the mandrel 5 slides during shearing along the length of the means pushing or advancing said mandrel.

The mandrel may have a circular or profiled cross section.

If it is intended to manufacture, for example, the semi-finished product required for producing female nuts, i.e. non-threaded female nuts from a compact, smooth bar of circular cross section, the cavity of the movable tool 1 will have a hexagonal cross sectionyso that when the mandrel 5 penetrates, both the internal bore and the hexagonal outer circumference of the female nut are formed, and the :metal must have a mechanical stress reaching at least the yield point. Then the chopping is performed, i.e. the stress produced for shaping is according to the invention, also employed for chopping by shearing. lf, however addi tional stress is required, it is possible to use the feed of the bar 4 for increasing the stress by making the bar 4 bear on the tool 1.

If alternatively no mandrel is employed, the axial feed pressure can be selected to be so high as to achieve flowing and upsetting of the metal contained in the die, so that it fills up the cavity. Compact profiled bodies may thus be produced. In this event too the main advantage of the invention is utilized, i.e. the stress produced for flowing is employed for chopping. ln other words, the stress brought about in the workpiece is used for a dualpurpose: plastic formation as well as chopping by shearing, without any scrap formation.

In the embodiment represented in FIGS. 2 and S the metal bar 4 is caused to bear upon the mandrel 5a with its conical extremity (FIG. 3). The mandrel acts also as an ejector means. During and/or after the feed the mandrel is displaced towards the left side of the drawing, whereupon the situation according to FIG. 2 is produced, i.e. both the cylindrical cavity in the movable tool and the conical cavity in the fixed tool 2 are filled up by the metal to be formed. Thereafter the cylindrical part is separated by shearing, on the action of the movable tool.

Of course the widening end of bar 4 may have a shape other than conical and the cross section of the part to be cut away may equally be other than cylindrical. In any case the advantage can be achieved that the diameter of the chopped-up product can be larger than that of the starting metal bar. A further advantage resides in the fact that the conical surface between the starting metal bar and the workpiece to be cut away offers a strong and reliable bearing surface against the pressure of the ejector mandrel 5a. In this manner greater stress can be produced in the metal bar, for identical feeding or clamping forces.

A further significant advantage of the method according to the invention is the elimination of difficulties due to the manufacturing inaccuracy (size tolerances) of the starting metal bar or wire, since the dimensions of the product upset in the cavity of the movable tool 1 are not influenced by the size tolerances of the starting metal bar. It follows from this that products of nonstandard dimensions may be easily manufactured from standard sized starting metal bars.

For achieving the above described advantages and for carrying out the described operational steps, it is not essential, to give the starting metal bar the conical shape according to FIGS. 2 and 3, but this conical shape is always produced in the course of the process. So at the beginning of the work the metal bar 4 may be cylindrical throughout, whereas in the course of producing the first chopped-off article a transitional portion is produced between the starting rod and the finished product, this portion having a cross section increasing towards the chopped-off article.

We claim 1. A process for the plastic formation and chopping of metal bars and wires with a fixed and a movable shearing tool, comprising introducing a metal bar into a die comprised in part by said movable tool, said die having a fixed part that progressively enlarges in the direction of said movable tool, pressing a mandrel against said metal bar thereby to subject a portion of the metal bar which is in the die to plastic deformation by flowing thus filling up the cavity of the die, and moving said movable tool and mandrel transverse to said fixed die part thereby to shear from said bar an article having a cross section substantially larger than the starting metal bar while leaving on said starting metal bar in said fixed die part an end portion of said starting metal bar that enlarges toward the shear plane between said article and said end portion of said starting metal bar.

2. A device for forming and cutting off workpieces from metal bars and wires, comprising a tool having a cavity therein of a size larger than the workpiece to be shaped, a mandrel movable in closely sliding relationship with the sides of the cavity to upset an end of the workpiece thereby to fill the cavity, the tool having a movable portion defining a portion of said cavity whereby upon conjoint movement of said movable portion and said mandrel, a portion of the upset end of the workpiece is sheared off, the mandrel being further movable to eject said sheared-off portion of the workpiece, said portion of the cavity defined by said movable portion of the tool being cylindrical, the remainder of t e cavity tapering from a great-est diameter adjacent said cylindrical portion to a least diameter remote from said cylindrical portion.

Claims

1. A process for the plastic formation and chopping of metal bars and wires with a fixed and a movable shearing tool, comprising introducing a metal bar into a die comprised in part by said movable tool, said die having a fixed part that progressively enlarges in the direction of said movable tool, pressing a mandrel against said metal bar thereby to subject a portion of the metal bar which is in the die to plastic deformation by flowing thus filling up the cavity of the die, and moving said movable tool and mandrel transverse to said fixed die part thereby to shear from said bar an article having a cross section substantially larger than the starting metal bar while leaving on said starting metal bar in said fixed die part an end portion of said starting metal bar that enlarges toward the shear plane between said article and said end portion of said starting metal bar.

2. A device for forming and cutting off workpieces from metal bars and wires, comprising a tool having a cavity therein of a size larger than the workpiece to be shaped, a mandrel movable in closely sliding relationship with the sides of the cavity to upset an end of the workpiece thereby to fill the cavity, the tool having a movable portion defining a portion of said cavity whereby upon conjoint movement of said movable portion and said mandrel, a portion of the upset end of the workpiece is sheared off, the mandrel being further movable to eject said sheared-off portion of the workpiece, said portion of the cavity defined by said movable portion of the tool being cylindrical, the remainder of the cavity tapering from a great-est diameter adjacent said cylindrical portion to a least diameter remote from said cylindrical portion.