US3867825A

US3867825A - Method and apparatus for cold forming rolled wire

Info

Publication number: US3867825A
Application number: US348078A
Authority: US
Inventors: Heinz Striepens; Horst Schulte
Original assignee: VEREINIGTE DRAHTINDUSTRIE GmbH
Current assignee: VEREINIGTE DRAHTINDUSTRIE GmbH
Priority date: 1972-04-05
Filing date: 1973-04-05
Publication date: 1975-02-25
Anticipated expiration: 1992-02-25
Also published as: DE2216368B2; DE2216368A1

Abstract

A method of and an apparatus for cold forming wires used as concrete reinforcing wires, the method comprises the steps of: unwinding a wire of a predetermined diameter, introducing the wire into at least one set of shaping rolls for reducing the cross section of the wire by at least 15% while polygonally shaping the wire, and thereafter repeatedly bending the wire in opposite directions to stress relief the wire to increase the elongation properties thereof. In the preferred method, the wire is continuously advanced and after polygonally shaping the wire, it is sent through another set of shaping rolls to form a substantially circular cross section for the wire while ribs or corrugations are formed at locations on the wire formerly occupied by corners when the wire was polygonally shaped.

Description

United States Patent [191 Striepens et al.

[451 Feb. 25, 1975 METHOD AND APPARATUS FOR COLD FORMING ROLLED WIRE [73] Assignee: Vereinigte Drahtindustrie GmbI-I,

l-lamm, Germany [22] Filed: Apr. 5, 1973 [21] Appl. No.: 348,078

[30] Foreign Application Priority Data Apr. 5, 1972 Germany 2216368 [52] US. Cl. 72/161 [51] Int. Cl B2lb l/l8 [58] Field of Search 72/161, 194, 187, 234, 72/160, 162

[56] References Cited UNITED STATES PATENTS 234,193 l1/l880 Mather 72/160 1,824,568 9/1931 Pierce 72/162 2,347,904 5/1944 Greulich 72/160 3,031,750 5/1962 VonPlanck 72/161 3,256,727 6/1966 Takaishi 72/234 3,348,400 10/1967 KOrf 72/161 3,494,164 2/1970 Rehm et al. 72/194 FOREIGN PATENTS OR APPLICATIONS 1,602,283 11/1970 France 72/161 Primary Examiner-Lowell A. Larson Attorney, Agent, or Firm-Fitch, Even, Tabin & Luedeka [57] ABSTRACT A method of and an apparatus for cold forming wires used as concrete reinforcing wires, the method comprises the steps of: unwinding a wire of a predetermined diameter, introducing the wire into at least one set of shaping rolls for reducing the cross section of the wire by at least 15% while polygonally shaping the wire, and thereafter repeatedly bending the wire in opposite directions to stress relief the wire to increase the elongation properties thereof. In the preferred method, the wire is continuously advanced and after polygonally shaping the wire, it is sent through another set of shaping rolls to form a substantially circular cross section for the wire while ribs or corrugations are formed at locations on the wire formerly occupied by corners when the wire was polygonally shaped.

15 Claims, 8 Drawing Figures PM ENTEU 5325975 3 867. 825

mm u or 5 Fig. 6

METHOD AND APPARATUS FOR COLD FORMING ROLLED WIRE This invention relates to a method of and an apparatus for manufacturing concrete reinforcing wires or rods.

Concrete reinforcing steel wires produced in accordance with conventional cold working methods have a relatively great difference between their yield points and ultimate tensile strengths with the result that the wires can be subjected only to limited low stresses. In some instances, the wires are subsequently treated, such as by an annealing process, to provide an increase in the elongation properties for these wires.

Concrete reinforcing steel wires of this kind have their surface configured with projections, corrugations or ribs for assisting in mechanical interlocking with the concrete. From a commercial standpoint, it is preferred that the concrete reinforcing wire be configured by a cold process without any subsequent annealing or tempering of residual stresses caused by the cold working. Also, the reinforcing wire should have all of the requisite technical properties of strength, yield point, elongation, dimensional accuracy and the shaped ribs or corrugations on the surface thereof. Moreover, the method and apparatus should be simple, trouble-proof and safe to operate, and capable of operation at relatively high speed. Also, the energy consumption for the process should be kept low.

Preferably, concrete reinforcing wire, which is subject to tension forces in use, should have a ratio of yield point to ultimate tensile strength of at least 0.9 and an elongation to breaking of at least 8%.

While several cold working processes have been proposed to make concrete reinforcing wires in the past,

these processes have not been adopted commercially because of various shortcomings therein. Thus, there is a need for a cold working process which eliminates the need for subsequent annealing or tempering of reinforcing wires when commercially producing reinforcing wires with a high ratio of yield point to tensile strength and with good elongation properties.

Accordingly, a general object of the present invention is to provide an improved method and apparatus for producing concrete reinforcing steel wire of the foregoing type.

Other objects and advantages of the invention will become apparent in greater detail when taken in connection with the accompanying drawings in which:

FIG. I is a schematic view of an apparatus for practicing the method of the invention;

FIG. 2 is an end view of the crown reels and the wire guide roller for use in the apparatus of FIG. 1;

FIG. 3 is a side elevational view of FIG. 2;

FIG. 4 is a diagrammatic view of a hydraulic circuit for controlling the operation of shaping rolls;

FIG. 5 is a schematic view of a stress relieving means;

FIG. 6 is a side elevational view of FIG. 5;

FIG. 7 is an enlarged view of a concrete reinforcing wire produced in accordance with the invention; and

FIG. 8 is an end view of the wire of FIG. 7.

As shown in the drawings for purposes of illustration, the invention is embodied in an apparatus 10 for forming a concrete reinforcing steel wire 11 having configurations on the surface thereof such as corrugations or ribs 12 for facilitating the mechanical interlocking of the wire to the concrete. In accordance with a preferred method of practicing the invention, the wire 11 is formed by steps of: unwinding a coiled wire and feeding the same forwardly from a means 14 supporting a wire coil 15, introducing the wire into at least one set of rolls 17 which polygonally shape the wire and reduce the cross section thereof by at least 15%, and thereafter repeatedly bending the wire in opposite directions by stress relief means 19 to stress relief the wire and to increase the elongation properties thereof. Preferably the wire is continuously traveling and advancing through the various stations and is drawn and wound upon a take-up reel means 21. As will be explained in greater detail hereinafter, the process provides a simple cold forming and working of a wire which results, as can be seen from Tables I and 2, in wires 11 having a ratio of yield point to ultimate tensile strength in excess of 0.90 and a breaking elongation in excess of 8%.

As will be explained in greater detail, during the shaping of the wire to form the ribs 12, the wire cross section is reduced considerably, i.e., at least 15% and in some instances as great as This improves the strength of the wire in the longitudinal direction, but as a result of this cold working, the elongation value for the steel wire decreases markedly, for example, by up to 50%. However, this very low elongation characteristic is raised subsequently by cold working in the stress relief means 19 which is in the form of a series of bending rolls 25 having surfaces for bending the wire rapidly and in opposite directions. Thus, many of the residual stresses causing during the shaping of the wire are relieved leaving the wire strong and ductile.

Referring now in greater detail to the illustrated embodiment of the invention, the preferred wire for use in the apparatus 10 will usually have a diameter of about 5 to 35 millimeters when it is in the coil 15. The preferred means for supporting the wire coils 15 are crown reels 27 which have upstanding spindles 31 inclined relative to the vertical at an angle of l0 to 30 to facilitate unwinding of wire from the coils telescoped onto the spindles. The coils 15 rest on pivotally mounted bases 29, which support the spindles and which may be pivoted downwardly to a horizontal position with the spindles being disposed in alignment with the vertical to facilitate loading of coils of wire thereon. The coils 15 rest on one side or flank of the spindles whereas the opposite side or flank of the coil has sufficient clearance to accommodate any twisting or entanglement during the unwinding of wire from the coil.

Preferably, the crown reels 27 are disposed in pairs as best seen in FIG. 2. Before the coil of wire is applied to one of the crown reels, its leading end is welded to the traling end of the opposite wire coil on the other crown reel so that it is possible to withdraw the wires continuously without interruption at the time of installing new coils of wire.

The preferred crown reels 27 have a spindle diameter which is from 0.2 to 0.9 times the mean ring diameter of the wire coil 15 placed thereon. Preferably, the crown reels have a spindle diameter of 0.5 to 0.7times the mean ring diameter for its coil. On the other hand, the crown reels 27 may be formed conically with a diameter thereof decreasing in an upward direction. In any event, sufficient clearance is provided to allow the wire to be detached from the coil while having a sufficient retarding force to prevent loops of wire from being withdrawn rather than the wire being unwound.

From the crown reels 27, the wire travels upwardly and passes into engagement with a guide roller 32 which is positioned centrally over the crown reels. The guide roller 32 rotates about a horizontal axis and is mounted in a bracket carried by a frame 33 projecting above the spindles 31 and centrally of the crown reels. The spacing of the guide roller 32 from the upper ends of the crown reel spindles 31 is at least 0.3 times and no more than 3.0 times the length of the peripheral dimension of the wire loop. The greater the diameter of the wire, the greater the spacing must be between the guide roller 32 and a crown reel 27.

From the guide roller 32, the wire may be advanced forwardly and downwardly to a conventional descaling means 34 which descales the wire in a conventional manner. From the descaling means 34, the wire passes forwardly in the illustrated apparatus to a preshaping means 35 comprising three rolls (not shown) displaced circumferentially about the wire from each other at 120.

In this illustrated embodiment of the invention, the wire leaving the coil is generally circular in cross section and within the set of rolls 35. It is generally preshaped as best seen in FIG. 8 to have a non-circular, generally polygon shape in the form of an equilateral triangular in cross section with flattened apices. For a wire having an initial diameter of7 millimeters, the preshaping rolls 35 have diameters from about 60 to 200 millimeters.

After preshaping of the wire in the set of rolls 35, the wire advances to the shaping means 17 having polygonal shaping or profiling rolls 41 which deform the wire at the three protruding apices and form crescentshaped ribs 12 as best seen in FIGS. 8 and 9 out of the metal. The ribs 12 are staggered longitudinally and arranged in three longitudinally extending row. In this instance, the ribs 12 protrude from the outlying or circumference of the wire surface 43 by about 6% of the wire diameter. Preferably, one row of ribs 12 is oppo-. sitely laid or directed relative to the ribs 12 in the other two rows.

When passing through the shaping means 17, the wire diameter should be reduced by at least 15% in order to provide directional tensile properties thereto which increase the strength of the wire. However, with this increased strength of the wire the wire becomes less ductile and the elongation values have been found to be decreased by up to 50%. It is only with the latter stress relieving operation that a breaking elongation of at least 8% and a 0.9 or greater ratio of yield point to ultimate tensile strength is obtained. Depending upon the required material qualities, the deformation may result in a decrease in cross section as great as 90% during the polygonal shaping operation. The periphery of the rolls 41 have cavities or projections to form the configurations in the wire such as ribs 12 while reducing the cross sectional dimension thereof.

To assure that the positions of the ribs 12 relative to one another do not shift during the shaping step, the rolls 41 are rotated at precise synchronism with each other. Preferably, this is achieved by driving the rolls 41 with a common or integrated hydraulic drive means 42 such as illustrated in FIG. 4. More specifically, hydraulic drive means comprises a motor 45 for driving a pump 47 to supply fluid under pressure to a common line 49 which leads to inlet lines 51a, 51b and 510 for each piston and cylinder drive 53 of a conventional kind. Each of latter rotates a drive shaft 52 for one of the three rolls 41. A common return line 55 is also connected to each of the hydraulic cylinder drives 53 to return the hydraulic fluid to the pump 47. A sump for the hydraulic system is also provided with a motor 57 driving a sump pump 59 to remove hydraulic fluid from a reservoir 61 to maintain the pressure and fluid in line 63 leading to the input line 49.

Sump return lines

65a, 65b and 65c are connected to each of the piston drive means 53 to return any excess fluid through a common sump return line 67 leading to the sump reservoir 61.

Thus, each of the individual piston drive cylinders 53 is connected in parallel by pressurized hydraulic fluid so that any differences in resistance or drag presented by the individual shaping rolls 41 are balanced against each other through the fluid. Also, the individual rolls 41 are interconnected and maintained in synchronism by means of the wire 11. That is, the rolls 4] compress the wire with high force, and in this way, rotate at equal self-regulating speeds without any slip. As a result, the ribs 12 and the rows thereof extend and are spaced exactly as desired longitudinally of the wire.

While the shaping rolls 41 are illustrated as being connected hydraulically, it is within the purview of the invention that they may be coupled to one another mechanically or by an electromechanical means so that the rolls 4] are kept in synchronism by feedback therebetween. The coupling of the shaping rolls 41 together prevents the wire from being drawn or upset between the set of rolls 41. The hydraulic drive for the rolls is preferred in that the speed of rotation of the rolls may be varied in an infinitely controllable manner while maintaining a synchronous rotation of the rolls. In the illustrated embodiment of the invention, the wire is advanced at 20 meters per second and may be increased to higher values.

For the purpose of stress relieving the wire, it is advanced from the shaping means 17 into the stress relief means 19 which comprises a number of rolls 25 positioned and cooperating in such a manner that the wire will repeatedly bend in opposite directions over a short distance to relieve residual stresses in the wire. By alternately compressing and tensioning opposite sides of the wire, much of the residual stresses generated by the preceding rolling operation in the shaping rolls 41 are removed. Also, the shaping of the wire causes it to become less ductile, e.g., 50% less ductile; but by the alternating compressing and tensioning of opposite sides of the wire in rolls 25, the elongation characteristic or limit for the wire 11 may be increased very substantially. Preferably, the successive bending movements and flexures are of such magnitude that the outermost phases or planes of the wire are each deformed in the plastic range. As will be seen from Table l, the breaking elongation exceeds the required value of 8% for the examples given. Thus it will be seen that the wire is cold worked eliminating the necessity that the wire be subsequently thermally annealed or tempered prior to being formed into mats or prior to being used as concrete reinforcing wires or rods.

The stressing relieving means 19 illustrated in FIG. 5 comprises four

upper rolls

25a, 25b, 25c and 25d and five

lower rolls

25e, 25f, 25g, 25h and 25i. The deflection of the wire is the greatest in this instance between the

rolls

25a and 25e with lesser bends being formed between the rolls 25c and 25g. The last of the series of rolls 25d and 251' are applying the least deflection. As

best seen in FIG. 6, the illustrated rolls 25 are supported at position to rotate about axles inclined at 45 to the vertical. More specifically, the four illustrated folls in FIG. 6 deflect the wire in four different directions at 90 to each other. These rolls 25 may rotate at and be disposed at other inclinations than that illustrated in FIG. 6.

The rolls 25 may be adjusted relative to a path of the wire therethrough to control the amount of displacement or bending of the wire by the individual rolls. Table 2 sets forth the results obtained when varying the deflecting or screwdown position for a roll 25. The zero position for the screwdown adjustment is defined as when a roll 25 contacts the wire without exerting any substantial pressure thereon to deflect the same. At the screwdown position 10, the deflection is very substantial.

After leaving the stress relief rolls 25, the wire may be sent through straightening rolls (now shown).

The wire 11 leaving the stress relief station is ready for usage and it may be cut to lengths or woven into a mat. In the illustrated apparatus, the wire leaving the stress reliefmeans 19 is advanced forwardly to a reeling means 21 which is likewise driven by a pressurized oil motor drive and piston assembly. To obtain a uniform pulling force on the wire from the reeling means 21, a reel drive means 51 includes a driving a piston and cylinder means, such as the piston and cylinder means 53 for the shaping rolls 25, driven by a constant pressure hydraulic fluid regardless of the quantity of consumption thereof. To retard the reel, the flow of pressurized fluid may be blocked in its return path from the piston and cylinder means so that the reel may be braked instantaneously and without any special retarding means.

In the illustrated embodiment of the invention, the wire is uncoiled and pulled through the descaling means 34 by the driven shaping rolls 41. However, in accordance with a further embodiment of the invention, the wire 11 may be drawn through the shaping means 17 and the stress relieving means 19 by having a wire drafting means, such as the reel means 21, pull the wire through an idling shaping means 17 and the stress relief means 19. That is, the separate drive means 42, shown in FIG. 4, for the shaping rolls 41 would be eliminated. Irrespective of how the wire is advanced, the stress relief rolls 25 will still be used subsequent to the shaping rolls 41 to provide the rapid bending or flexing within the plastic range.

By way of example only. steel wires having an initial diameter of 7mm was formed into the illustrated wire 11 having crescents 12 thereon and with finished cross sectional diameters of 6mm. These reinforcing wires had the strength characteristics shown here below:

TABLE 1 Starting product:

Rolled wire having a diameter of 7.0 mm

Cold rolled to: Concrete reinforcing wire of 6.0 mm of diameter Sample Tensile Yield Point Yield Point Breaking Elongation No. Strength Ratio B S kg/mm kg/mm S B TABLE 2 Dependence of the breaking elongation 10 from the screwdown adjustment of the relief rolls Sample Screwdown Breaking Elongation Increase of the breaking elongation It has been found to be insignificant whether the wires have a circular cross section, a profiled cross section or a corrugated surface. Also, the polygonal shaped wire may shaped in to a circular cross sectioned wire with ribs or corrugations in the region of the polygonal corners by an additional set of rolls prior to be stress relieved. The increased tension values and elongation values of the concrete steel reinforcing wires made in accordance with the invention allow the same to be used in applications which require a greater tension or stressing of the wire at reinforced concrete reel constructions.

In the production of concrete reinforcing steels, the wire may be formed with a corrugated surface. In such event, the corrugations when passing through the relief rolls 25 receive a further small bending because the outer surfaces of the corrugations contacting the rolls are bent in a greater degree than the smooth points which pass through the rolls 25. This additional superimposed bending frequency for the corrugations has been found to provide improved stress relieving effect for this kind of wire.

From the foregoing, it will be seen that a substantial reduction in cross section of the wire is used to not only form the surface for mechanically interlocking with the concrete but also to increase the directional properties of the wire which raises the yield point and the ultimate tensile strength of the wire. With the reduction of the cross section of the wire by amounts substantially less than l%, the yield point and ultimate strength are not substantially increased. Thus, it is definitely preferred to have sufficient reduction in cross section to provide this resultant increase in yield point and tensile strength for the wire. For some steel wires, the reduction in cross section has been as much as 90%. Cold shaping of the extent to reduce the cross section by l5% makes the metal harder and stronger but significantly less ductile, e.g., a loss in elongation of 50%. However, by the stress relieving in the rolls 25, the elongation property is substantially improved and the resulting wire has a high yield point to tensile strength ratio and a high elongation characteristic.

From the foregoing, it will also be seen that the method is relative simple and can be implemented with a continuous advancing wire to provide a high speed process. The elimination of the annealing or tempering of the wire is of particular importance from a production and economic standpoint. The process may be readily implemented with existing equipment and made to operate economically. The resulting reinforcing wire not only can be used in ordinary concrete reinforcing applications but also may be used in applications in which the reinforcing wire will be subject to high tension loads.

While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure but, rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

at least one set of rolls for polygonally shaping the wire and for reducing the cross section of said wire by at least l5% while shaping the wire, and thereafter repeatedly bending the wire in opposite directions to stress relief the wire to increase the elongation properties thereof, the wire being shaped and stress relieved to have a ratio between yield point and ultimate tensile strength of at least about 0.9.

2. A method in accordance with claim 1 including the further step of continuously advancing said wire while shaping and bending the wire; and subsequent to the shaping of the wire, passing polygonally shaped wire through at least one additional set of shaping rolls to form the wire into a substantially circular cross section configuration.

3. A method in accordance with claim 2 including the step of forming ribs or corrugations in the corners of the polygonally-shaped wire when shaping it into a substantially circular cross sectional configuration.

4. A method in accordance with claim 1 including the further step of passing the wire through the shaping rolls and driving the shaping rolls.

5. A method in accordance with claim 1 including the further step of drawing the wire through the shaping rolls and stress relief rolls.

6. A method in accordance with claim 1 in which the successive bending or flexures for stress relieving are of such mganitude that at least the outer portions of the wire are each deformed to beyond the elastic range of the wire but within the plastic range of the wire.

7. A method in accordance with claim 1 in which said wire is formed with portions on the outer surface thereof which when stress relieved are subject to smaller, unilateral bends of high frequency.

8. An apparatus for cold forming wires suitable for use as concrete reinforcing wires, said apparatus comprising means for supporting a coil of wire, means for uncoiling and advancing the wire forwardly from said coil, shaping means for polygonally shaping said wire while reducing the cross section thereof by at least 15%, and stress relief means for repeatedly bending the wire in rapid succession and in opposite directions to increase the elongation value of said wire, the wire being shaped and stress relieved to have a ratio between yield point and ultimate tensile strength of at least about 0.9. l

9. An apparatus in accordance with claim 8 in which said means for supporting said coil of wire comprises crown reels inclined at an angle between about 10 to 30 relative to the vertical.

10. An apparatus in accordance with claim 9 in which said crown reels are pivotally mounted to swing between the horizontal loading position and an inclined position for unwinding of wire from the coil.

11. An apparatus in accordance with claim 8 in which said shaping rolls include three sets of rolls displaced from each other by an angle of about the circumference of the wire.

12. An apparatus in accordance with claim 8 in which said stress relief means comprises a series of rolls ppositioned adjacent each other and extending longitudinally of the path of movement of said wire. said rolls having surfaces engaging the wire to bend it successfully in alternating directions.

13. An apparatus in accordance with claim 8 in which a takeup reel means is provided to coil the shaped wire to exert a tension force on said wire, said 15. An apparatus in accordance with claim 14 comprising a wire guide roller positioned above said crown reel, said guide roller being positioned above the upper end of the crown reel by a distance within the range of 0.3 to 3.0 times the means diameter of the coil of wire to be unwound.

Claims

1. A method of cold forming wires for use as concrete reinforcing wires, said method comprising the steps of: unwinding a wire of predetermined diameter and advancing the same forwardly, introducing the wire into at least one set of rolls for polygonally shaping the wire and for reducing the cross section of said wire by at least 15% while shaping the wire, and thereafter repeatedly bending the wire in opposite directions to stress relief the wire to increase the elongation properties thereof, the wire being shapeD and stress relieved to have a ratio between yield point and ultimate tensile strength of at least about 0.9.

8. An apparatus for cold forming wires suitable for use as concrete reinforcing wires, said apparatus comprising means for supporting a coil of wire, means for uncoiling and advancing the wire forwardly from said coil, shaping means for polygonally shaping said wire while reducing the cross section thereof by at least 15%, and stress relief means for repeatedly bending the wire in rapid succession and in opposite directions to increase the elongation value of said wire, the wire being shaped and stress relieved to have a ratio between yield point and ultimate tensile strength of at least about 0.9.

9. An apparatus in accordance with claim 8 in which said means for supporting said coil of wire comprises crown reels inclined at an angle between about 10* to 30* relative to the vertical.

11. An apparatus in accordance with claim 8 in which said shaping rolls include three sets of rolls displaced from each other by an angle of 120* about the circumference of the wire.

12. An apparatus in accordance with claim 8 in which said stress relief means comprises a series of rolls ppositioned adjacent each other and extending longitudinally of the path of movement of said wire, said rolls having surfaces engaging the wire to bend it successfully in alternating directions.

13. An apparatus in accordance with claim 8 in which a takeup reel means is provided to coil the shaped wire to exert a tension force on said wire, said take-up reel means being driven by a hydraulic fluid having a constant pressure.

14. An apparatus in accordance with claim 8 in which said means for supporting said coil of wire comprises a crown reel having a diameter between 0.2 to 0.9 times the mean coil diameter for the wire to be unwound.

15. An apparatus in accordance with claim 14 comprising a wire guide roller positioned above said crown reel, said guide roller being positioned above the upper end of the crown reel by a distance within the range of 0.3 to 3.0 times the means diameter of the coil of wire to be unwound.