WO1994025701A1

WO1994025701A1 - Three-dimensional reinforcing element of metal wire, and a method and means for manufacturing such element

Info

Publication number: WO1994025701A1
Application number: PCT/SE1993/000392
Authority: WO
Inventors: Björn Svedberg
Original assignee: Svedberg Bjoern
Priority date: 1993-05-05
Filing date: 1993-05-05
Publication date: 1994-11-10
Also published as: AU4031293A

Abstract

Reinforcing element, which is intended to be placed in a casting form together with concrete and comprising three metal wire rings (A, B, C), which forms angles to each other. Each wire ring is in contact with another wire ring at at least two junctures, and the wire rings constitute portions of a single coherent continuous metal wire (1) bent into the rings. The rings (A, B, C) formed of this single metal wire (1) are circular-annular and have at least approximately the same diameter. Such a reinforcing element is produced as follows: an initial first portion of the single continuous metal wire length (1) is bent in a first plane so that a first wire ring (A) is formed comprising at least one complete wire ring winding, whereupon a subsequent second portion of the metal wire length (1) bent in a second plane perpendicular to the first wire ring plane so that a second wire ring (B) is formed comprising approximately one and a quarter wire ring winding. A final, third portion of the metal wire length (1) is then bent in a third plane perpendicular to the planes of the first and second wire rings so that a third wire ring (C) is formed comprising at least one complete wire ring winding. The process can be carried out by means of a device with driving and guiding wheels which feed the wire (1) to a wire bending unit which imparts the passing wire a retained bent shape before the wire continues into a wire ball forming housing wherein there is a movable bending roller for bending a formed wire ring 90° relative to the wire entering the housing. There is also a wire cutting unit in the device.

Description

Three-Dimensional Reinforcing Element of Metal Wire, and a Method and Means for Manufacturing such Element.

The present invention relates to firstly, a reinforcing 5_. element of the type described in the preamble to patent claim 1, and secondly a process and a device (machine) for manufac¬ ture of such reinforcing elements, as according to the pream¬ ble to claim 5 or 7 and claim 8.

0 A reinforcing element of this type is intended to be placed in a casting mold together with concrete and consists of wire. It comprises at least three wire rings forming angles with each other, each wire ring being in contact with and/or joined to wire ring at at least two points of intersection. 5

Prior art

Concrete is a very frequently used construction material. Among the various types of concrete can be mentioned water¬ proof concrete, floating concrete and light weight concrete. 0 Concrete materials also sometimes include asphalt concrete. Since the tensile strength for unreinforced concrete only amounts to about 10% of its compression strength, reinfor¬ cement is usually placed in the concrete. The reinforcement can consist of rods, wires, bars, nets, lines, cables and the 5 like, usually of steel. Fibres of metal or organic material can also be used as reinforcement in fibre reinforced con¬ crete.

When casting concrete constructions to be reinforced, the 0 reinforcement (usually steel reinforcement) is laid in the casting mold prior to casting, and the concrete mass is filled into the mold. This requires much work with many different steps and involves many groups of construction workers. 5

The tensile strength of a concrete construction, which can thus be increased appreciably with the aid of conventional reinforcement, can also be increased by distributing a number of small metal elements in the concrete mass. Such metal elements in the form of steel wires for example have, howe¬ ver, the disadvantage that they must be long (i.e. have a length which is about 100 times the wire diameter) to provide the required adhesion in the concrete. If one uses metal elements provided with hooks at the ends, the elements can be made shorter, but they risk hooking into each other forming clusters, making them difficult to handle. Regardless whether such elongated elements have end hooks or not, it is, how¬ ever, difficult to distribute them evenly in the concrete mass. Even distribution of metal elements is, however, a precondition for fulfilling their function and providing effective reinforcing effects.

The above mentioned disadvantages can, however, be avoided by using the type of wire ball-like reinforcing elements which are described in US A 3,913,295. This known reinforcing element consists of three wire rings welded together, each ring consisting of a separate wire piece, the ends of which are welded together to form the closed wire ring or hoop. Such "reinforcing balls" avoid the risk of adjacent elements hooking together and forming clusters and makes it possible to achieve an even distribution of the reinforcing balls in the concrete. The reinforcing balls can also be mixed into the concrete mass right at the concrete station and there is no risk that they will sink and form a single layer at the bottom of the container in which the concrete mass is stored or transported prior to casting.

The known wire ball reinforcing element has, however, not come into widespread use since it has proved to have a number of serious disadvantages, on the one hand, as regards manu¬ facturing and costs, and on the other hand, as regards rein¬ forcement and strength.

Reinforcing elements which are to be used in great numbers must of course be able to be mass produced in an efficient and cost effective manner. This is, however, not possible with the known "reinforcing ball" consisting of three separa- tely produced endless wire rings, which in a subsequent step are welded together to form a reinforcing ball.

The manufacture of such a wire ball first requires the manu- 5_. facture of three finished, separate rings, each of which must be made from a separately formed piece of wire which is cut and welded at its ends to form a closed ring. The three finished rings must then be held in place in three planes at right angles to each other and then be welded together into a 0 finished ball. This method of manufacture requires a total of nine welds for each finished reinforcing ball.

Such a welded reinforcing ball therefore cannot be manufac¬ tured at sufficiently low costs to be of commercial interest. 5

The properties as regards reinforcement and strength of the welded reinforcing ball makes it in many cases more or less unusable as a reinforcing element. In many concrete construc¬ tions, where visible rust may not appear at or near the 0 concrete surface, the welded ball cannot be used since it rusts as a whole if it is made of a weldable steel, and rusts at the welds if it is made of cold drawn steel.

A welded ball (such as a ball of carbon steel) cannot be allowed to lie in the surface layer of a concrete cast since it rusts. In order to avoid rust it must be provided with a covering concrete layer. Welded wire balls can also not be used if there is a risk that they will end up against the mold wall, i.e. in the surface layer of the casting. All 0 weldable steel is in this context unsuitable since it rusts.

In general welding of wire material into a reinforcing ball involves a significant undesirable decrease in the strength of the ball. Welding a wire involves both reduced extensibi- lity and reduced resistance to fatigue, i.e. the risk of small cracks increases in size. This means that toughness characteristics will be poorer than what is normally prescri¬ bed for reinforcement, namely 1% distributed extension after rupture. For this reason it is important to refrain from using welded, cold worked steel. Today 500 mPa is accepted as a maximum yield stress limit in cold worked reinforcement even in the form of mesh reinforcement, which has welded ties. Wire which is welded together must therefore be avoided in supporting structures. Furthermore it is desirable to use reinforcing wire with a substantially higher yield stress limit than 500 mPa to provide a reasonable reinforcement content when using balls. The higher the yield stress limit is the higher will be the yield stress limit fall and the clearer will be the reduction in extensibility. In order to be able to use reinforcement balls effectively and economi¬ cally it is thus essential that welding be avoided, and that the rest of the manufacturing process not result in local brittleness or reduction in strength.

In summary, welding of the wire material in the reinforcing ball results in sharply reduced strength values, destroys the rust protection of the material and gives rise to inelastici¬ ty (brittleness) at the welding locations.

The purpose of the invention

Therefore, the purpose of the invention is to provide a reinforcing element in the form of a non-welded reinforcing ball of continuous wire material. This wire reinforcing ball shall also be simple and inexpensive to manufacture, i.e. the manufacture must be able to be done by means of a simple process which is well suited for carrying out in a simple machine or device, which can be made as a compact structure.

Presentation of the invention

The above purposes can be achieved according to the invention by virtue of the fact that the wire rings constitute portions of a single coherent continuous metal wire, bent to the shapes of the rings, and in that the wire rings formed of said single metal wire are essentially circular-annular and have at least approximately the same diameter, whereby the outer contours of the wire rings of the element provide the element with a spherical outer contour. Each wire ring is preferably disposed in a separate plane, said wire ring planes being essentially normal to each other. At least one of the wire rings has a circumferential area where the wire is doubled, said double wire area having an 5_. arc extent approximately corresponding to one fourth of the wire ring winding.

At least one, and preferably both, of the free end portions of the continuous metal wire forming the wire rings of the 0 reinforcing element is/are bent in towards the centre of the reinforcement element. This provides effective engagement between the wire material and the concrete mass in the inner space of the reinforcing ball. This also minimizes the risk of adjacent reinforcing balls becoming entangled in each 5 other by means of the free ends portions of the wires.

The reinforcing ball of continuous wire (galvanized or stain¬ less) presents no problems lying at the surface of the cas¬ ting (or against a form wall) and thus do not require a 0 separate covering layer of concrete, and can thus be placed directly in the form. By virtue of the fact that the reinfor¬ cing ball made of a continuous wire is entirely without welds, there is completely avoided the reduction in strength when welds are involved. 5

The reinforcing ball made of a continuous wire also has the great advantage that the tensile forces transmitted by the ball reinforcement are distributed over the entire reinfor¬ cing ball. 0

The technical reinforcing effect (i.e. the capacity to trans¬ mit tensile forces in a reinforced concrete structure) is clearly superior to that of a reinforcing ball consisting of separate, endless rings welded together.

A "ball-shaped" reinforcing element of the above mentioned type can be manufactured according to the invention by means of a process the characteristic steps of which are as fol¬ lows: A single, continuous length of metal wire is used to form the reinforcing element, whereby: a) a first portion of the metal wire length is shaped by bending into a first wire ring, whereafter the wire is bent approximately 90° at the end of the first wire and, b) a subsequent second portion of the length of metal wire is shaped by bending into a second wire ring disposed in a plane essentially perpendicular to the plane of the first wire ring, the bending and shaping of the wire continuing however, approximately one fourth of a wire ring winding after comple¬ tion of the second wire ring so that the wire is doubled in the overlapping area of the second wire ring, whereupon the wire is bent approximately 90° at the end of the overlapping area, and c) a final third portion of the metal wire length is shaped by bending into a third wire ring disposed in a plane essen¬ tially perpendicular to the planes of both the first and the second wire rings.

A preferred embodiment of the reinforcing element can also be manufactured by taking the steps disclosed in claim 6.

A process for manufacturing the reinforcing element according to the invention can also, as an alternative, be defined as stated in claim 7.

The invention also relates to a device for manufacturing a wire reinforcing element of the above mentioned type. This device, according to the preamble of claim 8, has the special features disclosed in the characterizing clause of claim 8.

Claims 9 and 10 disclose additional further developing featu¬ res of the device.

In the device according to the invention the metal wire is advanced with the aid of driving and guiding wheels which advance the wire to a wire bending unit which imparts a retained bend to the passing wire. A wire ball forming hou¬ sing is arranged downstream in the wire advancing path with an interior, at least essentially cylindrical, wire bending space with an inner diameter approximately twice the radius of the curvature of the retained wire bend achieved by the wire bending unit. In the wall of the ball forming housing there is a wire feed-in opening through which opening the bent wire from the bending unit can pass over the lateral surface of a bending roller reciprocately moveable in the longitudinal direction of the cylindrical bending space. The movement of said roller, transverse to the wire coming from the feed-in opening is capable of bending the wire approxima- tely 90°. Upstream of the wire feed-in opening there is also arranged a wire cutting unit through which the wire passes. This wire cutting unit serves to cut off the metal wire coming from the wire magazine when the wire length required for a complete reinforcing ball has passed the cutting unit. This cutting unit can be disposed with the wire bending unit, but can also be placed in the wire advancing path between the driving and guiding wheels which feed the wire to the wire bending unit.

Short description of the drawings

The invention will now be described and explained further below with reference to examples shown in the accompanying drawings of a ball-like reinforcing element according to the invention and devices for carrying out a process for manu- facture of the reinforcing element.

In the drawings:

Fig. 1 is a perspective view of the reinforcing element (a reinforcing wire ball) according to the invention; Fig. 2 shows schematically a device according to the inven¬ tion suitable for manufacture of a reinforcing wire ball; Fig. 3 shows very schematically the essential components of a second embodiment of the device according to the invention; and Fig. 4 shows an end view from above of the device according to Fig. 3.

Description of examples Fig. 1 shows a preferred embodiment of a ball-like reinfor¬ cing element according to the invention. The reinforcing consists of metal wire and comprises three continuous wire windings A, B and C. These wire ring windings or wire rings A, B, C are located in individual planes essentially perpen¬ dicular to each other. The three wire rings A, B and C each stand in contact with the two other wire rings at at least two junctions. Particularly characteristic of the reinforcing element according to the invention is that the three wire rings A, B, C constitute coherent parts of a single conti¬ nuous length 1 of metal wire, which according to the Figure extends from the free end portion A' to the other free end portion C at the opposite end of the continuous wire. The wire rings A, B and C are thus different portions or sections of a single continuous length of metal wire. The three wire rings A, B, C are essentially circular rings of approximately the same diameter. The reinforcing element thus is given a "ball-like" appearance and therefore the reinforcing element in this description is also called a reinforcing wire ball or a reinforcing ball. Since the first wire ring A is circum¬ scribed by the second wire ring B which is in turn circum¬ scribed by the third wire ring C, the wire rings have of course slightly different diameters.

As can be seen in Fig. 1, one of the wire rings, namely ring B, has a circumferential portion 2, within which the wire is doubled. This double wire portion 2 has an arc length which corresponds approximately to one fourth of a wire ring win¬ ding. The two free end portions A' and C of the continuous metal wire, which form the three wire rings A, B and C are bent towards the interior of the reinforcing ball, so that the outermost ends are directed approximately towards the centre of the reinforcing ball.

The reinforcing ball shown in Fig. 1 is manufactured in the following manner:

A single continuous length 1 of metal wire is used in the manufacture of the reinforcing element. A first portion of the metal wire length 1 is formed by bending in a first plane into a first wire ring A, whereafter the wire is bent appro¬ ximately 90° at the end 3 of the first wire ring A. Thereaf¬ ter a subsequent second portion of the metal wire length 1 is formed by bending in a second plane into a second wire ring B, the plane of which is thus disposed essentially perpendi¬ cular to the plane of the first wire ring A. The bending and forming of the wire 1 in this second plane is, however, continued approximately a fourth of a wire ring winding after the completion of the second wire ring B, so that the wire 1 will be doubled within this parallel wire area 2 of the second wire ring B. The wire 1 is then bent approximately 90° at the end 4 of the parallel wire area 2, and a final third portion of the metal wire length 1 is formed by bending in a third plane into a third wire ring C, the plane of which will then be substantially perpendicular to the planes of both the first and the second wire rings (A and B) .

A pair of devices suited to manufacture of the reinforcing wire balls, corresponding to that shown in Fig. 1, will now be described with reference to Figs. 2-4.

A continuous, straight metal wire 1 is supplied to the device 10 from a wire magazine (not shown) , such as a reel of wire. From this wire magazine, the wire 1 is fed by driving and guiding wheels 12 and 14 respectively towards a tubular wire ball forming housing 16 with an interior, at least essential¬ ly cylindrical, wire bending space. In order to facilitate the description of the device, the forming housing 16 has been provided with a "window" 18 which, however, will not be found in the actual device 10. In the lateral wall 20 of the tubular wire ball forming housing 16, there is a flat wall portion 22 in the form of a radial extension. This flat wall portion 22 is provided with a wire feed-in opening 24, through which the wire 1 can be fed into the interior of the wire ball forming housing 16. At a suitable location in the wire advancing path between the guide wheels 14 and the wire feed-in opening 24, there is a wire bending unit 26, which imparts a retained bend in the passing wire having a radius of curvature approximately corresponding to one half of the inner diameter of the wire bending space of the forming housing 16. Near the wire feed-in opening 24 there are dis¬ posed next to the flat wall portion 22 a pair of cooperating 5. drive rollers 28, 30, between which a drive nip is formed, through which the wire 1 passes from the feed-in opening 24 before it continues over the lateral surface of a bending roller 32 which can move up and down in the axial direction of the forming housing 16. By virtue of the fact that the 0 wire l, when it enters the wire bending space of the forming housing 16 already has approximately the same radius of curvature as the lateral wall 20 of the forming housing 16, the wire 1 can without difficulty during continued feeding into the housing 16 form a ring along the inside of the 5 lateral wall 20 of the housing. With a first such wire ring (which is to form the first wire ring A of the reinforcing ball shown in Fig. 1) has been completed inside the forming housing 16, the vertically movable bending roller 32 makes a vertical bending stroke 1 upwards (see the arrow F in Fig. 2) 0 so that the finished first ring A is bent about 90° to the incoming wire 1 from the drive nip between the rollers 28 and 30. In order for the bending roller 32 to be able to execute said bending stroke, it is journalled on a shaft (not shown) which is movable in a plane parallel to the flat wall portion 5 22 and extending out through the lateral wall 20 through a vertical slot 34 in the lateral wall. The bending roller 32 returns thereafter and the feeding of the wire 1 into the wire ball forming housing 16 is continued until a second wire ring (such as wire ring B in Fig. 1) , comprising one and a 0 quarter winding, is formed inside the wire bending space in the housing 16. By means of the bending roller 32 there is then made at the end 4 of the parallel wire area 2 of the second wire ring B a new 90° bend in the wire so that the second wire ring will be vertically oriented in the housing 16. The feed-in of the wire into the housing continues as the third wire ring (for example the wire ring C in Fig. 1) is formed inside the forming housing 16. To cut off a length of wire suitable to the reinforcing ball to be made, a wire cutting unit 36 is arranged upstream of the wire feed-in opening 24. The wire thus passes through this wire cutting unit before the wire continues in through 5_. the feed-in opening 24. When the entire wire length cut off by the wire cut-off unit 36 has passed in to the opening 24 and through the nip between the rollers 28 and 30, the manu¬ facture of the complete reinforcing ball is finished and the finished wire ball can then fall down through the tubular 0 wire ball forming housing 16 into a "ball bin" below the device.

A somewhat differently constructed device or machine for manufacture of a reinforcing wire ball according to the 5 invention will now be described with reference to Figs. 3 and 4.

The device shown in Figs. 3 and 4 agrees in principle in all essential respects with that shown in Fig. 2 except that 0 there are no wire driving rollers 28 and 30 on the inside of the flat wall portion 22 near the wire feed-in opening 24. The bending roller 32 is in this case instead arranged adja¬ cent the inside of the wall portion 22. The 90° bending of the fed-in wire 1 is accomplished in this case with the aid 5 of the bending rollers 32 and against the edge of the feed-in opening 24 instead of against the nip between the rollers 28, 30 as shown in Fig. 2. The wire cut-off unit 32 is in this case integrated in the wire bending unit 26, which is in turn mounted directly on the outside of the flat wall portion 22. 0 This placing of the bending unit 26 is best shown in Fig. 4, which also shows how the bending roller 32 is journalled on a shaft 38 extending through the lateral wall 20. The driving and guiding wheels 12, 14 respectively in this embodiment of the device can correspond to the driving and guiding wheels in Fig. 2. Fig. 3 shows the situation where a first wire ring has just been made in the wire bending space of the ball forming housing 16.

Claims

1. Reinforcing element intended to be placed in a casting form together with concrete, such as light weight concrete,

5_. asphalt or a corresponding mass, said reinforcing element consisting of wire, preferably metal wire or the like, and comprising at least three wire rings (A, B, C) , which form angles to each other, each wire ring being in contact and/or being joined to another wire ring at at least two junctures, 0 c h a r a c t e r i z e d in that the wire rings (A, B, C) constitute portions of a single coherent continuous metal wire (1) bent to the shapes of the rings, and in that the wire rings (A, B, C) , formed of said single metal wire (l) , are essentially circular-annular and have at least approxima- 5 tely the same diameter, whereby the outer contours of the wire rings of the element provide the element with a spheri¬ cal outer contour.

2. Reinforcing element according to claim 1, c h a r a c - 0 t e r i z e d in that each wire ring is disposed in a sepa¬ rate plane, said wire ring planes being essentially normal to each other.

3. Reinforcing element according to Claim l or 2, c h a - r a c t e r i z e d in that at least one (B) of the wire rings has a circumferential area (2) where the wire (1) is doubled, said double wire area having an arc extent (2) approximately corresponding to one fourth of a wire ring winding.

4. Reinforcing element according to one of claims 1-3, c h a r a c t e r i z e d in that at least one (A' or C) , and preferably both of the free end portions (A', C) of the continuous metal wire (1) , forming the wire rings (A, B, C) of the reinforcing element is/are bent in towards the center of the reinforcing element.

5. Method of manufacture of a reinforcing element consisting of wire and comprising at least three wire rings forming angles to each other and being in contact and/or joined to each other at junctures between the rings, c h a r a c ¬ t e r i z e d in that a single continuous length (1) of metal wire is used to form the reinforcing element, whereby a 5_. first portion of the metal wire length is shaped by bending into a first wire ring (A) , whereafter the wire is bent approximately 90° at the end of the first wire ring and a subseqeuent second portion of the length of metal wire is shaped by bending into a second wire ring (B) disposed in a 0 plane essentially perpendicular to the plane of the first wire ring (A) , the bending and shaping of the wire (1) conti¬ nuing, however, approximately one fourth of a wire ring winding after completion of the second wire ring, so that the wire (1) is doubled in the overlapping area (2) of the second 5 wire ring (B) , whereupon the wire (1) is bent approximately 90° at the end (4) of the overlapping area (2) , and a final, third portion of the metal wire length is shaped by bending into a third wire ring (C) disposed in a plane essentially perpendicular to the planes of both the first and the second 0 wire rings.

6. Method according to Claim 5, c h a r a c t e r i z e d in that the free end portion (A') of the wire (1) at the beginning of the first wire ring (A) is imparted a special bending inwards towards the centre of the reinforcing ele¬ ment, and that the free terminating end portion (C) of the wire (1) at the end of the third wire ring (C) is imparted a particular bending inwards towards the center of the reinfor¬ cing element.

7. Method of manufacture of a reinforcing element consisting of wire and comprising at least three wire rings, which are disposed in separate planes and are in contact or are joined to each other at junctures, c h a r a c t e r i z e d in that an initial, first portion of a single continuous metal wire length (1) is used to form by bending in a first plane a first wire ring (A) comprising at least one complete wire ring winding, a subsequent intermediate second portion of the metal wire length (1) being used to form by bending in a second plane essentially perpendicular to the first wire ring plane, a second wire ring (B) comprising approximately one and a quarter wire ring winding, whereafter a final, third portion of the metal wire length (1) is used to form, by 5 bending in a third plane perpendicular to both the planes of both the first and the second wire ring, a third wire ring (C) comprising at least one complete wire ring winding.

8. Device (10) for manufacture of a reinforcing element

10 consisting of wire and comprising at least three wire rings disposed in separate planes and connected to each other at wire junctures, c h a r a c t e r i z e d in that the wire is a metal wire (1) which is supplied to the device from a wire magazine with the aid of driving and guiding wheels (12,

15 14) , which feed the wire into a wire bending unit (26) which imparts a retained bend to the passing wire, and that a wire ball forming housing (16) is arranged downstream in the wire advancing path with an interior, at least essentially cylin¬ drical, wire bending space with an inner diameter approxima-

20 tely twice the radius of curvature of the retained wire bend achieved by the wire bending unit (26) , there being a wire feed-in opening (24) in the wall of the ball forming housing (16) , through which opening the bent wire from the bending unit can pass over the lateral surface of the bending roller

_____ (32) , reciprocately movable in the longitudinal direction of the cylindrical bending space, the movement of said roller, transverse to the wire coming from the feed-in opening (24) being capable of bending the wire approximately 90° and upstream of the wire feed-in opening (24) there is arranged a

30 wire cutting unit (36) through which the wire passes.

9. Device according to claim 8 , c h a r a c t e r i z e d in that in the area of the wire feed-in opening (24) there is adjacent to the housing wall a pair of cooperating wire drive 35 rollers (28, 30) between which there is formed a wire drive nip through which the wire from the feed-in opening passes before it continues to the bending roller (32) .

10. Device according to claim 8 or 9, c h a r a c t e r i ¬ z e d in that the wire ball forming housing is tubular and has in its lateral wall (20) a flat wall portion (22) projec¬ ting radially, and that the bending roller is journalled on a shaft (38) which is movable in a plane parallel to the flat wall portion (22) in the lateral wall (20) and extends out through the lateral wall (20) through a slot (34) parallel to the flat wall portion.