US3928998A

US3928998A - Metal rod for reinforced concrete and process for producing said rod

Info

Publication number: US3928998A
Application number: US442008A
Authority: US
Inventors: Hector Jose Torres
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-11-28
Filing date: 1974-02-13
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30
Also published as: GB1508343A; FR2296693A1; DE2511812A1

Abstract

Process for producing a metal rod with a high yield point and pronounced capability of adhesion, for reinforced concrete and the like, where the periphery of the rod is provided with series of spaced apart anchoring studs which have substantially the same physical properties as the core of said rod; and a process for producing such a rod by shaping and forming the starting material only by means of pressure and without subjecting the rod during the manufacture to torsion.

Description

United States Patent 11 1 1111 3,928,998

Torres Dec. 30, 1975 1 METAL ROD FOR REINFORCED 2,552,364 5 1951 Bradbury 72/198 CONCRETE AND PROCESS FOR 3,494,164 2/1970 Rehm et a1. 72/187 PRODUCING SAID ROD lnventor: Hector Jose Torres, Buenos Aires,

Argentina Leonardo Francisco Aurelio, Buenos Aires, Argentina; :1 part interest Filed: Feb. 13, 1974 Appl. No.2 442,008

Assignee:

Foreign Application Priority Data Nov. 28, 1973 Argentina 251204 US. Cl. 72/185; 72/187; 72/197 Int. Cl. B21 8/00 Field of Search 72/187, 197, 198, 185;

References Cited UNITED STATES PATENTS Jenks 72/187 Primary Examiner-Lowell A. Larson Attorney, Agent, or FirmFleit & Jacobson [57] ABSTRACT Process for producing a metal rod with a high yield point and pronounced capability of adhesion, for reinforced concrete and the like, where the periphery of the rod is provided with series of spaced apart anchoring studs which have substantially the same physical properties as the core of said rod; and a process for producing such a rod by shaping and forming the starting material only by means of pressure and without subjecting the rod during the manufacture to torsion. 1

7 Claims, 20 Drawing Figures U.S. Patent Dec. 30, 1975 Sheet 1 of2 3,928,998

US. Patent Dec.30, 1975 Sheet2of2 3,928,998

PROCESS FOR PRODUCING SAID ROD BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a metal rod, preferably of iron, with a high yield point and pronounced capability of adhesion, for reinforced concrete and the like, as well as to a metal rod produced by such a process.

For the purpose of the present invention the expression rod is used to define a stick-like member, which has usually a rather small cross-sectional circular area of a diameter not larger than approximately 8 mm.

The expression bar is used to identify a larger, elongated metal member than a rod and which has, in general, a considerably higher rigidity than the rod", as well as a larger cross-sectional area.

2. Description of the Prior Art Iron reinforcement bars used in reinforced concrete structures are well known; iron rods have smaller crosssectional areas or diameters than the bars and are used in reinforced concrete members which are subject to smaller loads, than reinforced concrete members having bars. Both, in the event of bars as well as rods, it is an aim to provide these reinforcing members with a high yield point, as well as a pronounced capability of adhesion with regard to the concrete in which they are to be embedded. In the manufacture of bars, these features are generally achieved by using as starting material iron bars of a predetermined length and on which periphery longitudinal ribs are formed by rolling. These ribbed bars are then subject to a torsional step to thereby increase the yield point and to change the shape of the longitudinal ribs into helicoidal ribs, to increase the capability of adhesion of the resulting reinforcing member within the concrete.

Upon carrying out the torsional step the yield point is particularly increased in the core of the bar, which is the portion which acknowledges best the benefits of such a torsional step.

However, on the perimetral zones of such a bar and in the portions defining the ribs, the result as to increasing the yield point is not so good and not so uniform as in the core portion of the bar. On the other hand, it is to be born in mind, that the ribs are precisely the portions of the bars which are subject to the greatest stress. Thus, it is an aim that these ribs should havethe highest possible yield point.

The manufacturing process of such bars, cannot be a continuous process, because it includes a torsion step, where the ends of the bar have to be clamped between a pair of spaced-apart revolving heads or chucks. The fact that the manufacturing process is an intermittent process is of no substantial importance in connection with the total manufacturing cost of such bars, bearing in mind the weight thereof.

In the event of rods, the cost of an intermittent torsion process to increase the yield point would have a substantial influence on the total cost of manufacture, bearing in mind the weight of such rods. In view of the foregoing, it is apparent that in theevent of rods, it would be very convenient to provide a continuous process by means of which it is possible to increase the yield point which at the same time should be substantially constant throughout the entire cross-sectional area of the rod. In addition, if the capability of adhesion with regard to the concrete, of such a rod could be increased, a considerable step forward would be achieved within this particular art.

Continuing with the comments on drawbacks and difficulties which are encountered, when using bars with helicoidal ribs, it is to be recalled that when such bars are embedded in a concrete member which is subject to load, that there is a tendency of such bar to move with regard to the concrete according to an axis which is coaxial with the axis of the helicoid which is defined by the rib. Because of this, the anchorage of such bar in a concrete member is not the optimum.

Rods of the diameters hereinabove mentioned, and used in reinforced concrete structures are generally not subject to any improvement process prior to be used; as a matter of fact in most cases just cylindrical rods are used.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for producing such rods with an increased capability of adhesion and a higher yield point than is the case in the orthodox untreated rods. To achieve such a result, the invention is based on the concept, that for increasing the yield point, bearing in mind that it is anti-economical to subject individual rods to a torsional process it is necessary to submit a strip in a first step to cold compacting, to thereby reduce the cross-sectional area of such a strip. The resulting member has already a higher yield point. This member is then subject to a second-step which is a shaping process without generating any torsional stress on the member, in order to obtain on the periphery of such member small stud like anchoring projections, which increase the capability of adhesion.

During the shaping process step, part of the metal of the member is moved, while the rest remains substantially unaltered. From the last mentioned unaltered portions, the anchoring projections are formed without substantially changing the metallographic structure of such portions. To be more specific, the unaltered portion will include the core of the rod, as well as the anchoring projections and which are precisely those which have to resist the more outstanding stresses, once the resulting rod is embedded in a concrete member, which is subject to pertinent loads.

The stud-like anchoring projections are preferably aligned and spaced apart among themselves in such a manner that they do not define a helicoidal path along the rod, whereby a better anchorage is achieved. In addition, the separation of the studs is selected in relationship to the size of the granules of the pertinent components of the concrete, such as sand, stone or gravel which may at least partially enter in the spaces defined in between such studs.

In addition, since the resulting rods are to be bent into the most variable shapes, special care is taken, that no sharp angles are formed at the portion where the studs merge into the core of the rod.

Preferably the studs are grouped in series.

The rods manufactured in accordance with the present invention are particularly used for stirrups, clamps, and the like; for tying reinforcement bars; they are also used in small concrete beams, slabs and road structures, as well as in prefabricated concrete members of small size.

The present invention relates thus to a process for producing a metal rod, preferably of iron, with a high yield point and pronounced capability of adhesion, for reinforced concrete and the like, comprising the steps of subjecting to cold compacting a metal strip, in order to reduce its cross-sectional area and increase the yield point of the metal constituting it, to produce a member having a substantially constant cross-section defining intersecting major and minor axes, and thereafter applying, on opposite peripheral portions of the member which includes said major axis, the necessary pressure to shift part of the metal from said opposite peripheral portions, and to form spaced apart studs by maintaining in longitudinally spaced apart zones the remaining part of the metal in said opposite peripheral portions, said studs defining the means to increase said capability of adhesion.

Within the inventive concept in relationship to the process, it is to be pointed out that there are other features, such as that the process is a continuous one; that the metal strip which defines the starting material for the process has a rectangular cross-sectional area and that the latter can be obtained by cutting a sheetlike metal plate of suitable thickness into a plurality of parallel strips.

The invention is likewise concerned with a metal rod which has a substantially cross-sectional circular area having a diameter not larger than about 8 mm and where diametrically opposite peripheral zones are provided with staggered projecting studs which have substantially the same high yield point as the material of the rod existing between said diametrically opposite peripheral zones which define the core of said rod. The studs are preferably staggered in series of several studs along the rod.

BRIEF DESCRIPTION OF THE DRAWINGS In order to facilitate the interpretation of the present invention, reference will now be made, by way of example to several embodiments, in relationship to the accompanying drawings, wherein:

FIG. 1 is a schematic perspective view, showing a hot rolled metal sheet roll which is being cut into parallel strips.

FIGS. 2, 2a, 3, 4 and 5 show schematic perspective views of several stations of a machine which enables to carry out the continuous process in accordance with the present invention.

FIGS. 2b, 3a and 5a are longitudinal sections through the pairs of rollers respectively shown in FIGS. 2a, 3 and 5.

FIG. 5b is a perspective view of a roller of the pair of rollers shown in FIGS. 5 and 5a.

FIGS. 6 to 12 are respective cross-sections according to lines VIVI, VII-VII, VIII-VIII, lX--IX, X--X, XI-XI and XII-XII which are shown in FIGS. 2 to 5, and in FIG. 12, there is in addition shown in dottedlines, the cross-sectional area of the member of FIG. 11.

FIG. 13 is an enlarged cross-sectional detail of a portion of the roller shown in FIG. 5b.

FIG. 14 is a portion of a finished rod, in accordance with the process of the present invention.

FIG. 15 is a schematic illustration of the process to which the starting material is to be subject, according to an arrangement which is an alternative embodiment with regard to the one shown in FIGS. 2 to 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, a metal sheet roll l is shown, from which parallel strips 2 are cut by means of a plurality of cutting disks 3. Upon unwinding roll 1, the pertinent portion of the unrolled flat metal sheet defines an upper face 4 and a lower face 5. The resulting cut strips 2 will also have each an upper face 4 and lower face 5 the lengths of which are larger than the thickness of the sheet member. These strips 2 are then individually wound on drums, one of which is partially shown in FIG. 2 and identified by reference numeral 6; the winding is so performed that the upper and

lower faces

4,5 become side faces. Referring now to FIG. 6, a section of strip 2 is there shown with the side faces 4,5, which are substantially parallel among themselves, and end faces 7,8, which are slightly irregular due to cutting of the disks 3.

One of the fundamental steps, according to the process of the present invention, resides in cold compacting these strips 2,to thus increase the resulting yield point. Tests have shown that such compacting is best achieved by applying pressure on the end faces 7,8. However, if such compacting would be directly performed on the irregular end faces 7,8, it would not be possible to achieve a uniform distribution of the compacting load. On theother hand, undue hardening of the metaldefining the end faces 7,8 when subject to compacting, should be avoided, since otherwise the later steps of the method of the invention could not be successfully performed.

Accordingly, a solution had to be found to transform the irregular end faces 7,8 into small ones, which enable to apply thereon uniformly distributed compacting loads. To this end, a pair-of idle shaping rollers 9,10 (FIG. 2a) mounted on pertinent shafts 11,12, only schematically shown, are provided to convert the substantially rectangular cross-sectional area (FIG. 6) into a cross-sectional area 13 having the shape shown in FIG. 7 and to which reference will bemade later on. The two

shaping rollers

9,10 have preferably the same diameter, for instance mm. Since the structure of both

rollers

9,10 is identical, reference will now be made only to roller 9. Roller 9 has a shaping channel 14 defined by two substantially parallel, side walls 15 and a concave-shaped bottom wall .16. The cross-sectional area of channel 14 is substantially equal to half of the cross-sectional area 13 (FIG. 7).

Strip 2 is fed from drum 6 and before entering the shaping station of

rollers

9,10, the

faces

4,5,7,8 are coated with a lubricant. Said coating may be performed in many well-known manners, for instance, by means of a sprayin-gun or passing said strip through a lubricant containing container, or as schematically shown in FIG. 2a, by passing such strip through a pair of

felt cylinders

17,18 to which lubricant is supplied by.means of a dosifier 19.

Rollers

17,18 are rotatably mounted on a pivoted support 20, which due to spring 21 maintains

rollers

17,18, in contact with the faces of the strip 2. The, lubricant used may, for instance, be a SAE 60 oil. The object of such lubrication is to enable the shaping of strip 2 through

rollers

9,10 with a minimum load or pressure.

If FIGS. 6 and 7 are compared, it may be appreciated that the-portions of material which are present in the corners defined by

faces

4 and 7; 7 and 5; 5 and 8; and

8 and 4, are moved, upon strip 2 passing through the shaping

station

9,10, whereby the distance between the;-

the distance existing between

faces

4 and 5 of strip 2,

shown in FIG. 6. It is because of this, that the distance which exists between the side walls of the channel,

14, is slightly larger than that which exists between the

faces

4 and 5, in order to permit the movement of such material and furthermore to obtain by means of the bottom-walls 16 the shape of faces 7' and 8'.

The load which is applied to

rollers

9 and 10 is the minimum necessary to carry out the shaping and is approximately 1,000 kg, if rods of approximately 5 mm diameter of the type used in reinforced concrete, are employed.

The shaping step up to here described, is not an absolutely necessary one, although convenient, in order to carry out the following compacting step in an optimum way.

To facilitate the explanation of the following steps'of the process of the invention, in the cross-sectional area 13 illustrated in FIG. 7, a major axis 22 and a minor axis 23 are shown, where the length of the major axis 22 is approximately equal to the distance which exists between the end faces 7 and 8 (FIG. 6). The

axes

22 and 23 cross each other.

In order to carry out the compacting step, the strip is now passed through a compacting station, consisting of a pair of compacting driven-

rollers

24,25. Actually, the compacting

station

24,25 is coaxial with the shaping

station

9, 10 and acordingly, the drawing should be interpreted in this manner. The compacting channels of rollers 24, have each seen in cross-section a semielliptical shape so that, as shown in FIG. 3a, the facing portions of the

rollers

24,25 define an elliptical space 26. Conveniently, the upper roller 24 has a slightly larger diameter (237 mm) than the lower roller 25 (235 mm), so that upon rotating both with the same number of revolutions (for example 72 r.p.m.) there is a tendency of the strip member to exit such station by downwardly curving, so that by locating at the outlet of the comparting station 24,25 a suitable discharge table 27 (FIG. 3) the resulting rod is rectilineally discharged from the lower roller 25. In the compacting

station

24,25, a considerable pressure or load is exerted on the convex end faces 7, 8' (FIG. 7) to transform the strip 2 into a rod having an elliptical cross-section and where the compacting is such, that the major axis 22 (FIG. 7) is transformed into the minor axis 28 (FIG. 8) and the minor axis 23 (FIG. 7) is transformed into the major axis 29 (FIG. 8). This rather substantial transformation implies a reduction in the cross-sectional area of the strip, transforming it into a rod 30 which is metallographically modified by considerably increasing its yield point. In the example which is being described, a load of approximately 2,200 kg is applied, which, with regard to the load applied at the shaping station 9,10 (1,000 kg), represents an increase of 120%.

Thus a rod 30 is achieved, the yield point of which has reached the desired value, but which rod is still lacking suitable anchoring means, which, in accordance with the concept of the present invention have to be produced without altering the physical features of the rod, at least in those portions which correspond to the future anchoring means and in the core of the rod, because these are the more important portions of the rod when subject to stress in a concrete member, in which it is to be embedded.

The anchoring means are merely small studs 31, such as shown in FIG. 14, where a finished rod 32 is shown. These studs 31 are present in series of three uniformily spaced apart studsand each series, in turn, is spaced apart from the next series in a distance which is larger 7 than the distance which exists between successive studs of the same series. In addition, the series of studs are aligned along diametrically opposite generators and one series of studs of one generatrix faces an interserial space of the other generatrix. As to the particular shape of the studs, reference will be made thereto later on.

The resulting rod 32 should have, apart from the studs 31, approximately a circular cross-section (FIG. 12).

In order to achieve all these features, it is convenient to shape the studs 31 in the zones corresponding to the ends of the major axis 29. In the embodiment which is being described, the elliptical rod 30, with its major axis 29 in a horizontal position, as shown in FIG. 9, is passed through a series of orienting

rollers

33, 34; 35,36; 37,38 (FIG. 4), in order that the rod is turned, so that its major axis 29 becomes vertical. To carry out this reorientation, without exerting a permanent torsional stress on the rod, the

pair'of rollers

33,34; 35,36;

37,38 are idly mounted on respective shafts in order that their pertinent channels will only carry out a guiding action. The first pair of

rollers

33,34 supports the rod 30 with the major axis 29 in horizontal position (see also FIG. 9). The second pair of

rollers

35,36 supports the rod 30 with its major axis 29 in a sloped position (for instance 45; FIG. 10) and the last pair of

rollers

37,38 supports the rod 30 with its major axis 29 in upright position (FIG. 11).

This rotation of the rod is merely performed to be able to feed the rod into an existing rolling mill, where only the conventional rollers have to be replaced by

rollers

39,40 to be described later on. Obviously, the guiding

rollers

33,34; 35,36; and 37,38 shown in FIG. 4 are coaxially arranged with the compacting

station

24,25.

Reference is now made to FIG. 12, which shows in dotted lines, the elliptical cross-section ,of rod 30 in upright or vertical position, similar to FIG. 11. Rod 30 is now passed through the stud shaping station consisting of a pair of driven rollers 39,40 (FIG. 5) arranged behind the guiding rollers, shown in FIG. 4. .These

rollers

39,40 have to rotate at a higher speed (for instance 83 r.p.m.) than the driven

rollers

24 and 25.

Also in the stud shaping station, the upper roller 39 has a larger diameter than the lower roller 40, for example 239 mm and 235 mm, respectively, in order to achieve the same result as in the compacting

station

24,25. In order not to overload the drawing, no discharge table has here been shown, but a table similar to table 27, shown in FIG. 3, is also used.

Each

roller

39,40 is as such of similar structure and each one has a channel 41 (FIG. 5b) which in general has a semi-circular cross-section, and which in their bottom walls have pluralities of holes 42, arranged in series to produce the already mentioned studs 31.

Obviously, the holes 42 of the upper roller 39 will be staggered with regard to bhe holes of the lower roller 40, to achieve thus the distribution of the studs 31, as shown in FIG. 14.

Referring now to FIG. 13, where one of the holes 42 is shown, it may be seen that the latter has a cap-shaped bottom portion, actually a spherical sector bottom portion with a radius 43 and the opening of which broadens to establish thus a linking zone with the walls defining the actual channel 41, defined by radius 44. It may be appreciated that this broadening zone, in this embodiment is defined by radii 45, the centers of ourvature 46 of which are located outside the cavity defined by channel 41, while the centers of

curvature

47 and 48 of the cap and the channel, respectively are located within the pertinent cavities. Thus, studs may be formed, the side walls of which join in a continuous curve like manner with the cylindrical surface of the rod.

Returning now to FIG. 12, it may be seen, that the elliptical rod 30, due to the fact that it has been previously orientated, may enter the inlet of the channel 49 defined by the

rollers

39,40 with its major axis 29 in upright position, so that the necessary pressure may now be applied on the opposite peripheric portions'of such body, in which the major axis 29 is located, in order to move a portion of the metal of these opposite peripheric portions by maintaining only the metal of the pertinent mid portions and which are to form the studs 31 while the rest of the metal is outwardly moved to increase the portion corresponding to the minor axis 28 and to thus transform the elliptical section 30 into a circular section 32' having the studs 31.

Referring again to FIG. 12, it may be seen that the zone of the finished rod 32, which is inscribed in a dotted line, is practically not subject to metallographic tranformations during the passage through

rollers

39 and 40 and that zone is the one which defines the core and the studs of the finished rod 32.

- Thus, a product is achieved having a high yield point and new anchoring means where these means and the adjacent zones of the core are not subject to undue pressure during the transformation which takes place when the rod is passed through

rollers

39 and 40, to produce the studs. The load which is applied to

rollers

39 and 40, in the example given, is approximately 3,300 kg. In other words, there is an increase of approximately 50% with regard to the load applied at the compacting

station

24,25. Although in absolute values, there is an increase of 50%, it should not be overlooked that in relative values, this increase is considerably smaller, because when the strip enters the shaping

station

9, 10 it has, for instance, a Rockwell hardness of -40, and upon leaving said station, a Rockwell hardness of B-55 and upon said strip entering the compacting

station

24,25 it still has the same hardness, i.e. Rockwell B-55; when said strip leaves the compacting station as a rod its hardness has been increased to B-65.

In other words, if the hardness at the inlet of the shaping

station

9, 10 is compared with the hardness at the outlet of the compacting

station

24, 25, it will be seen that there is an increase from 40 to 65 Rockwell B. On the other hand, upon entering the rod to the

studshaping station

39, 40, it has, as already stated, a hardness of Rockwell B-65 and upon leaving the latter its hardness has only slightly increased, namely to Rockwell B-70. This means that the pressure increase which is applied at the stud-shaping station is the necessary minimum in order to be able to produce the studs as explained, bearing in mind that the material that is there used has a hardness of Rockwell B-65.

In FIG. 5, a cutter 50 is schematically shown which may cut the rod which leaves

station

39, 40 into rod members having a predetermined length.

In FIG. 15, a similar arrangement is shown with regard to the one described in connection with FIGS. 2a

to 5; the difference resides in that in the embodiment of FIG. 15 no guiding rollers of the type shown in FIG. 4, are used, and on the other hand, the stud-forming station consists of a pair of rollers 39' and 40' arranged according to the horizontal. Apart from this fact, the same reference numerals have been used as in the prior Figures, so that it does not become necessary to redescribe the entire arrangement.

Although several embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts, without departing from the spirit and scope of the invention, as the same will now be understood by those skilled in the art.

I claim:

1. A process for producing a metal rod having a high yield point and good adhesive properties for use with reinforced concrete or the like, comprising the steps of:

producing an elliptical rod having intersecting major and minor axes by subjecting a metal strip to cold compacting in order to reduce the cross-sectional area thereof and to increase the yield point of the metal constituting said elliptical rod;

applying pressure to said elliptical rod at peripheral locations thereof located at opposite ends of said major axis;

allowing a portion of the metal at said locations to shift toward other peripheral locations of said rod, said other peripheral locations being at the opposite ends of said minor axis thereby increasing the amount of metal located at said other peripheral location while simultaneously maintaining another portion of the metal of said rod unshifted and substantially free of metalographic transformation, said another portion forming a core and studs and being located adjacent said major axis, the shifting of said material causing studs to be formed out at said peripheral locations while said shifted material transforms said elliptical rod to a circular rod having studs thereon.

2. Process according to claim 1, comprising the previous steps of cutting longitudinal strips from a sheet member to define strips having each a rectangular cross-section, where the sides of minor lenght are the cut faces and then shaping these cut faces to transform them into uniform surfaces, and that prior to that shaping step, each strip is coated with a lubricant, that after the shaping step a compacting pressure is applied on said uniform surfaces, thereby carrying out said cold compacting, whereby the substantially rectangular section, having a major axis and a minor axis, which cross each other, is transformed into an elliptical section, in such a manner that the major axis of the rectangular section becomes transformed into the minor axis of the elliptical section and the minor axis of the rectangular section becomes transformed into the major axis of the elliptical section.

3. Process according to claim 2, wherein the compacting step is carried out by moving the strip through a pair of compacting rollers.

4. Process according to claim 3, wherein the shaping of the cut faces, the compacting step for transforming the rectangular section into an elliptical section and the shaping of the studs is carried out in a continuous and successive manner.

5. Process according to claim 1, wherein the studs are produced in aligned series along two diametrically op- 10 in turn, is spaced apart from the next series in a distance which is larger than the distance which exists between successive studs of the same series.

7. Process according to claim 1, wherein said studs have side walls which merge by means of a continuous curve into the peripheral surface of said rod.

Claims

1. A process for producing a metal rod having a high yield point and good adhesive properties for use with reinforced concrete or the like, comprising the steps of: producing an elliptical rod having intersecting major and minor axes by subjecting a metal strip to cold compacting in order to reduce the cross-sectional area thereof and to increase the yield point of the metal constituting said elliptical rod; applying pressure to said elliptical rod at peripheral locations thereof located at opposite ends of said major axis; allowing a portion of the metal at said locations to shift toward other peripheral locations of said rod, said other peripheral locations being at the opposite ends of said minor axis thereby increasing the amount of metal located at said other peripheral location while simultaneously maintaining another portion of the metal of said rod unshifted and substantially free of metalographic transformation, said another portion forming a core and studs and being located adjacent said major axis, the shifting of said material causing studs to be formed out at said peripheral locations while said shifted material transforms said elliptical rod to a circular rod having studs thereon.

5. Process according to claim 1, wherein the studs are produced in aligned series along two diametrically opposite generators of the rod, having a circular cross-sectional area, the interserial space of adjacent series of studs is larger than the space existing between adjacent studs of the same series, and each series located along one generatrix generally facing the interserial space of two adjacent series of the other generatrix of said rod.

6. Process according to claim 5, wherein each series has three uniformly spaced-apart studs and each series in turn, is spaced apart from the next series in a distance which is larger than the distance which exists between successive studs of the same series.