US1945877A - Metal working and article produced thereby - Google Patents

Description

Feb. 6, 1934. F. R. BONTE METAL WORKING AND ARTICLE PRODUCED THEREBY Filed April 17, 1929 Patented Feb. 6, 1934 UNITED STATES PATENT OFFICE.

I METAL WORKING AND ARTICLE PRODUCED THEREBY Frederick R. Bonte, Beaver Falls, Pa. W Application April 1'7, 1929. Serial No. 355,856

16 Claims.

This invention relates to the art of metal working, and more particularly to a process'and apparatus for reducing the cross-sectional area of a metal article with the consequent elongation thereof. production of an improved The invention relates further to the bar or wire of a desired cross-sectional shape, having superior qualities to rods made by the usual hot rolling process, and is especially applicable to the manufacture of ferrous or steel bars. I

According to the present practice of manu facturing rods from billets,

the billets, after being heated to approximately a welding temperature, are passed through a which the cross-section of the billet is'successiveseries of hot rolls in ly reduced and the length successively increased until, upon emerging from the last roll, there is an elongated rod or bar having the desired crosssectional shape.

In making bars according to, the usual hot rolled process the metal is only reduced approximately to .the desired diameter, a wide tolerance bearing permissive in material of this character.

If the bar .is to be used for screw machine purcold drawing.

In the operation of the hot rolled process a very considerable portion of the metal is ultimately wasted in the form the bars can be cold drawn of scale and before they must be pickled to remove the scale. Furthermore, the billet, which usually has a square cross-sectional shape,

is reduced to a round or ov al shape, and in this process of reduction the corners of the square billet are lapped over, and

unless the metal is being worked at the proper temperature a surface defect will frequently develop which renders the bar useless for practically poses.

all commercial pur- In a process of hot rolling, where it is desired to change the diameter ofor the cross-sectional shape the finished product,

of the finished prod-' uct, it is necessary to change the rolls of a rolling mill which is a cumbersome operation. 7

According to the presen and time consuming t invention there is provided a method and apparatus by which a esired cross-sectional tolerances generally practice without re- This process is applicable either in connection with a hot rolled bar, or to a bar which has been reduced either wholly or partially by a method other than hot rolling.

The invention further contemplates a process by means of which'a billet or other large object can be reduced and elongated to bar and rod form either wholly or partially by the use of reducing dies, thereby eliminating wholly or in part the use of hot roll stands.

The invention further contemplates a process of forcing an article to be reduced or-modified in cross-sectional shape through a die in a manner which will work the grain of the metal and develop an improved product.

The invention may be readily understood by reference to the accompanying drawing which illustrate one embodiment of my invention. It will be understood that the drawing is more or less diagrammatic and are intended merely for the purpose of illustration, and that the invention is not restricted to the particular construction and arrangement of parts therein disclosed. In the Y drawing,

Figure 1 represents a plan view of a single unit for efiecting a reduction of metal or a modification of the cross-section of metal according to the present invention,

Figure 2 is anend view of the apparatus shown in Figure 1,

Figure 3 represents a section through one of the threading units by means of which the article to be reduced is forced through the die.

Figure 4 is a view similar to Figure 3 of a reversely. threaded unit, and

Figure 5 is a view similar to Figures 3 and 4 showing a cross-section through the reducing die.

According to the present invention the article to be reduced is forced through a die of the proper cross-sectional shape and dimension by the continuous application of a force tending constantly to push the metal through the die. The die may be of either the solid or built-up type and somewhat similar to the die used in cold drawing operations, or it may be comprised of pressure rollers through which the metal is pushed without the application of any pulling tension on the delivery side of the die and without being forced through the die, when the die is in the form of rolls, by any pulling force exerted by the rolls themselves.

According to one manner of practicing my invention a die having a suitable cross-sectional shape and dimension is operatively interposed between the last stand of rolls in the hot rolling process and the hot bed on which the bars are received. The last stand of rolls impels the rod forwardly through the die at such speed and with sufficient momentum to cause the rod to travel through the die, and in passing through the die the metal is reduced to the desired cross-sectional shape or dimension.

With this method the rod is practically completely reduced by the usual hot rolling process, and the die serves only to keep the rod to the necessary cross-sectional size, and the rod which is so produced will be within the tolerances to which it is necessary to hold the rod. The rod will have a finish which is superior to the usual hot rolled rod, and does not have to be cold drawn in order to permit of its use in automatic machinery.

Instead of the metal being impelled through the die by the force of the last roll in a reducing train of rolls, other means may be employed for imparting the necessary travel to the bar, and such other means are preferably employed where-the metal is reduced either directly from the billet, or only in the final stages by means other than the usual roll stands, or where the change in cross-sectional shape offers such resistance to the passage of metal through the die as renders the provision of additional or other impelling means desirable.

The machine or apparatus as disclosed in the drawing is one wherein reducing steps are effected without the use of roll stands. In this apparatus 2 designates the bed or frame work of a machine. Mounted for movement along the bed is a carriage 3. A threaded rod 4 extending longitudinally of the bed of the machine is provided "for reciprocating the carriage back and forth along the bed of the machine. This screw may be selectively driven to drive the carriage forwardly or backwardly in any suitable way. I have shown reversely driven pulleys 5 and 6 with a clutch 7 for driving the threaded shaft 4, the pulleys 5 and 6 being driven through belts 8 and pulleys 9 on a drive shaft 10.

Mounted on the carriage 3 is a rod gripping mechanism 11 of any suitable or preferred construction. This mechanism may be of the type used, for instance, in pushing a bar into a die in starting the operation of cold drawing.

On the frame 2 are mounted one or more reducing units, the number depending upon the amount of reduction to be accomplished, and for convenience of illustration I have shown only one such unit. Each unit preferably includes two solid or built-up threading dies 12 and 13 arranged in tandem and each rotatably mounted in a stationary housing 14, which housings are carried on the framework 2. The dies are provided with removable thrust rings or collars 15 by means of which they are restrained against endwise movementin the housings, and they are provided with driving pulleys 16. Separate belts l7 engaging pulleys 18 on the shaft 10 serve to rotate the two threading dies. The driving arrangement is such that the die 12 rotates in a di rection reversed to the die 13. I have shown a crossed belt for the die 13 by means of which this reverse rotation .is secured. It will be understood that instead of belts, any gearing of a suitable or preferred type may be used for rotating the dies. Following the second threading die 13 is the reducing die 19. The reducing die 19 as preferably constructed has a bore 20 therethrough of a desired cross-sectional shape and size to which the finished product is. to be reduced and a portion of this bore is flared or tapered at 21 to provide a mouth for the easy entrance of metal being worked upon and the gradual reduction of said piece to that portion of the bore of smallest diameter. From the portion of smallest diameter the metal emerges from the die as a finished product.

The reducing die may be held in a stationary position upon the framework, but is preferably mounted to rotate where the product being manufactured has-a circular cross-section. 'In order to permit the die to be rotated, the die is located in a housing 22 mounted upon the frame and is provided with a pulley 23 around which passes a belt 24, this belt also passing around a pulley 25 on a power shaft 10. Thrust collars 26 are mounted on the die to hold the same against endwise movement.

The die 19 may be of a one piece construction, or may bev built-up of different parts. Instead of being similar to a drawing die, it may be comprised of a plurality of rolls so arranged and positioned as to provide a pass therebetween of the desired shape.

In reducing a piece of metal, it is first heated to an operating temperature, after which it is firmly secured in the gripping means 3, and the gripping means is advanced until its end enters the opening in the leading die 12. As this die is revolving it will take hold of the metal and impress helices or threads into the surface of the metal. Since the metal is being held against the rotation by the gripping means 3 this threading action of the die 12 will serve to push the bar forwardly toward the next die 13. The second die 13 revolves in a direction opposite the die 12 and serves to counteract the tendency which the die 12 has torotate the bar. The die 13 takes hold of the metal, working a helix thereon, and the metal is pushed forwardly into the forming die 19. After the piece has been engagedby both of the rotating dies 12 and 13 it may be released by the gripping means3 because the rotation of one of the dies ina direction opposite to the rotation of the other serves to hold the bar against rotation. The impulse produced by the two threading dies will be sufficient to force the heated piece through the reducing pass of the reducing means or die 19-so as tochange or reduce the cross-sectional size and possibly the shape of the piece of metal. Naturally, if the cross-section of the metal is reduced the length of the article is increased.

It is proposed that a sufiicient number of reducing units may be arranged in succession to permit of the reduction of solid or pierced billets to bars or tubes of the desired cross-sectional dimensions, mandrels of course being used where the operation is carried out upon pierced billets. It is further proposed that a billet may be reduced partially by the usual process of hot rolling and further reduced to a finished product by one or more stages of reduction as herein disclosed.

By the use of the process of reduction as herein disclosed, an article of improved characteristics is obtained. The formation of helices in the surface of the work and the subsequent elimination of them by the reducing die forges the grain structure of the metal, imparting superior properties to the product obtained by the usual process of hot rolling.

In place of the gripping unit 3, my invention contemplates that rolls may be used for feeding the metal to the threading dies and for holding the bar against free rotation. These rolls, of which there would. preferably be two horizontal and two vertical, may be designed to impress the beginning of the thread or helix in the bar.

The threaded dies are of course designed to assume the proper flow of the metal without rupturing or breaking the same. To this end, the thread which is formed is shallow and gradual, providing a wave like contour rather, than a sharply defined thread. v

It will be understood that the apparatus shown in the drawing is diagrammatic, being intended merely for the purpose of illustrating the principle of my invention, and various changes and modifications may be made therein according to the nature of the work being performed. Such changes and modifications are within the contemplation of my invention and come within the scopof the following claims.

I claim:

1. The process of working metal as herein described which comprises the continuous formation of a helix on the surface of a hot, parallelsided piece of metal while holding the piece of metal against the rotation and utilizing the threading action to impel the piece through a fixed reducing die and eliminating the helix in the reducing pass.

2. The method of working metal to modify the cross-sectional dimensions thereof which comprises forcing the metal through the opening in a reducing die having a cross-sectional opening corresponding to the contour of the emerging shape, which opening is adapted to modify the cross-sectional shape of the metal piece, formed by threading the piece while it is held against rotation, and utilizing the threading action to impel the piece through the die, and simultaneously work the metal on the surface of the piece.

3. The process herein described which comprises forcing a hot metal piece through the opening in a reducing die having a cross-sectional opening corresponding to the contour of the emerging shape, which opening is smaller than the metal piece, by forming a thread on the surface of said piece first in one direction and then in the other and while holding the piece against rotation.

4. The process herein described which comprises forcing a hot metal piece through the opening in a reducing die, which opening is smaller than the metal piece, by forming a helix in said piece in one direction and then forming a helix on the piece in the opposite direction, the formation of the helices serving to push the metal through the die and at the same time work the metal to improve the grain structure thereof and remove surface defects therefrom.

5. The process of forcing a piece of metal through the opening of a reducing die having a cross-sectional opening corresponding to the contour of the emerging shape which comprises forming a thread on the surface of said piece in one direction, while restraining the piece against rotation, and then forming a thread on the surface of it in the opposite direction, the second thread forming operation being effected before the first one is completed.

6. Apparatus for reducing the cross-sectional area of a piece of metal comprising a reducing die, having a cross-sectional opening corresponding to the contour of the emerging shape, means spaced in advance of the die rotatable coaxially about the metal for continuously forming a helix in the surface of a metal piece, means for restraining the piece against rotation, said helix forming means serving to force the metal piece through the die, the die serving to remove the helix formed by said helix-forming means.

'7. As a new article of manufacture a metal rod or the like which has been reduced to size by the formation in the surface of the metal of a plu- 'rality of opposing helices and which helices have been subsequently removed by the forcing of the metal through a die having a cross-sectional opening corresponding to the contour of the emerging shape whereby the surface of the rod has a grain structure distinct from that existing in a rod formed by a process of hot rolling and cold drawing.

8. As a new article of manufacture,a metal rod or the 1ike, the grain of the metal of which is similar to that'obtained in a rod into whose surface a spiral groove has been rolled, a spiral groove then rolled in the opposite direction which grooves have been subsequently'removed by the forcing of the rod through a reducing die having a cross-sectional opening corresponding to the contour of the emerging shape.

9. An apparatus of the class described comprising a clamp for holding a bar to be processed,

means for moving said clamp longitudinally, thread forming means in line with the clamp and a die member in line with the thread forming means, said die member having an opening there- 11. In an apparatus of the class described, a

die having a reducing pass therein, means disposed in advance of said die and separate therefrom for producing an undulatory surface on a rod to be passed through the die, a clamp mem-' ber adapted to hold the rod against rotation in advance of said means and movable toward and away therefrom, and means for actuating said clamp member back and forth toward the said means.

12. An apparatus of the class described comprising a die having a reducing pass therethrough, a guide member in advance of the guide having a helical threadtherein and arranged to form a helix on a rod passing therethrough to the die, I

means for rotating said guide member, and a clamp member movable toward and away from the guide member and having means thereon for gripping the rod to be fed through the guide member and die, said reducing die having a crosssectional opening corresponding to the contour of the emerging shape. a

13. An apparatus of the class described comprising a die having a reducing pass therethrough,

a guide member in advance of the guide having a helical thread therein and arranged to form a helix on a rod passing therethrough to the die, means for rotating said guide member, a clamp member movable toward and away from the guide member and having means thereon for gripping the rod to be fed through the guide member and die, and a second guide member interposed between the first guide member and die and being arranged to produce a helix on the surface of the rod passing therethrough reverse to the helix of the first guide member.

14. A method of hot working a metal rod which comprises heating the rod, then impressing a helix into the surface of the rod without subface of the rod in such reducing pass.

rolling temperature,

into the surface of the rod without substanstantially changing the rod, then impressing 9.

overall dimension of the helix into the surface of the rod reverse to the first helix and thereafter forcing the rod while still hot through a reducing pass and eliminating the helix from the sur- 15. The method of hot'working a metal rod which comprises heating the rod to a normal hot then impressing a thread tially changing the overall dimensions of the rod and while holding the rod against rotation, whereby a forward thrust is imparted to the rod and utilizing the forby the threading action,

rod while hot through

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