EP0222141B1 - Apparatus for forming on a steel wire strand a bulge projecting outward - Google Patents

Abstract

An apparatus for forming a radially outwardly directed bulge in an axially extending stranded steel wire cable for use as an anchor in a concrete structural component includes a frame with a pair of side walls. A clamping device is mounted on one end of the frame for gripping the stranded cable. The clamping device has two displaceable clamping jaws connected to counter jaws by articulated levers for moving the clamping jaws into the closed or clamped position. The clamping jaws are closed by a piston-cylinder unit mounted in the frame. Spaced from the clamping device on the frame is a sliding carriage with a thrust member into which one end of the stranded cable is inserted. The sliding carriage is connected to the piston-cylinder unit. After the clamping device is closed, the sliding carriage and thrust member are moved toward the clamping device by the piston-cylinder unit and the individual wires of the stranded cable are displaced axially and radially outwardly into a radially extending bulge against the inside surface of an upsetting pipe located between the clamping device and the thrust member.

Description

The invention relates to a device for producing a bulge on a strand of steel wire as anchoring in components made of concrete, the strand being axially compressed at its free end over a region of its length and thus the individual wires being axially deformed with spreading, consisting of a A frame is provided at one end with a clamping device with two clamping jaws and at the other end a pressure piece that can be displaced via a cylinder-piston unit that can be acted on from both sides, and in between a compression tube that is displaceable in the longitudinal direction, both the pressure piece and the compression tube having means , which allow the strand to be twisted freely during upsetting.

In addition to steel bars, steel wires and steel wire bundles, strands made of high-strength steel wires have also been used increasingly as reinforcement elements, above all for prestressed concrete. Such strands consist of a central wire, around which the outer wires are grouped in a symmetrical manner in one, sometimes in two annular layers. The outer wires are twisted, similar to a wire rope.

Strands as tendons are usually anchored using wedges. Wedge anchors are relatively complex both in terms of the material and in terms of the time required for installation; This is particularly important if the anchorage in question is to be concreted in firmly, i.e. if the tendon does not need to be tensioned at the anchor point. In addition, it is difficult to achieve sufficient vibration resistance with wedge anchorings without additional measures.

For the firm, i.e. non-tensionable anchoring of strands, it is known to compress the strand at its free end by applying axial pressure so that the individual wires form a bulge under plastic deformation, which can be embedded in a concrete component for anchoring the strand. For the production of such a bulge, a device is known in which the bulge takes place at least over the part of its length with the largest outer diameter within a compression tube running coaxially to the strand axis, on the inner wall of which the wires bear during the compression and on which they can unwind (DE-OS 32 07 957). In this way, a uniform, slowly increasing spatial curvature of the individual wires of the stranded wire can be achieved with a particularly large sum of the deflection angles, which enables anchoring with a short development length and very good fatigue behavior.

A problem with such upsetting devices is the clamping device, which is intended to hold the strand during the upsetting process. If clamping jaws are used for this, they have to be driven hydraulically, which makes the compression device very complex and heavy overall. The clamping force can be generated more easily by means of wedges. However, if wedges are used to hold the strand, they must be provided with teeth on the inner surfaces in order to generate the required holding force. Here, however, there is a risk that the teeth will cut into the surface of the strand and damage the strand wires.

Accordingly, the invention has for its object to provide a device of the type mentioned, which allows the strand to be clamped gently with clamping jaws, the clamping force being generated just as easily as when using wedges, in which the clamping pressure is adjustable , in which no special devices and operations are required to remove the stranded wire, and which is also space-saving and easy to transport and operate.

According to the invention this object is achieved in that the frame has two mutually spaced side cheeks which carry the clamping device at one end and at the other end a sliding carriage is movable, which carries the pressure piece on the one hand and on the other hand the cylinder -Piston unit is attached that the clamping jaws are guided parallel to fixed counter-jaws by means of toggle levers arranged in rows and that a two-armed lever is pivotally mounted on the frame, one end of which is operatively connected to the cylinder-piston unit while its other end is supported against the end faces of the jaws.

The slideways required for the displacement of the sliding carriage can be formed on sliding rails. The slide can expediently be moved between the side cheeks and overlaps the slideways.

As a result of the parallel guidance of the clamping jaws on toggle levers arranged in rows, the clamping jaws swivel in evenly so that the strand is held securely in the frictional engagement. The use of toggle levers to generate the clamping force on the strand has the further advantage that the clamping force increases as the toggle levers and the other movable parts of the clamping device become worn. Increasing wear does not lead to a loss, but rather to an increase in the functionality of the device. Since the clamping jaws are closed by means of a double-acting cylinder-piston unit, the clamping jaws open again automatically when the piston is returned to the starting position, so that the braid provided with the bulge can be lifted out of the device without further manipulation.

Lifting out the braid provided with the bulge is facilitated if the upsetting tube is as far as possible from the clamping device. The displacement of the compression tube in the longitudinal direction required for this purpose is served in each case by a longitudinal slot provided in the side cheeks, in which a sliding device for the compression tube is guided in the manner of a link. If between Sliding device and the sliding carriage a frictional engagement exists, the upsetting tube with the sliding carriage is automatically retracted when the piston is retracted with the sliding carriage.

The clamping device is expediently provided with an adjustable stop for the clamping jaws. By correctly setting this stop to match the length of the toggle lever, the clamping force can be dosed so finely that the strand is held securely without the risk of damaging the surfaces of its wires.

An opening mechanism for the clamping jaws can also be provided on the clamping device, which supports their return to the open position after the end of an upsetting process. The opening mechanism expediently has a spring element, preferably a compression spring, which presses the respective clamping jaws in the opening direction via a pin.

For safe and material-saving power transmission via the toggle levers, the clamping jaws and the associated fixed counter-jaws of the clamping device have arcuate recesses against which the toggle levers, which are also rounded at the ends, are supported in an articulated manner. In this way, considerably higher forces can be transmitted than if the support were only provided via axle bolts, which, however, can be provided, but then essentially only for pivoting the jaws back into the starting position and for captively storing the parts of the clamping device in the open state serve.

The pressure piece expediently has a bore for receiving the central wire of a strand, the depth of which can be adjusted. An adjusting screw can be provided to adjust the depth.

For easier handling of the device, a holder with a handle and foot is used, which is screwed onto the outside of the side cheeks of the frame with a base plate and at the same time reinforces the frame in the region of the longitudinal slot.

• Fig. 1 eine Seitenansicht der Vorrichtung,
• Fig. 2 eine Draufsicht auf die Vorrichtung nach
• Fig.1,
• Fig. 3 eine Stirnansicht der Vorrichtung gemäß der Linie 111-111 in Fig. 1 und
• Fig. 4 einen Querschnitt durch die Vorrichtung entlang der Linie IV-IV in Fig. 1.

The invention is explained below with reference to an embodiment shown in the drawing. It shows

• 1 is a side view of the device,
• Fig. 2 is a plan view of the device
• Fig.1,
• Fig. 3 is an end view of the device along the line 111-111 in Fig. 1 and
• 4 shows a cross section through the device along the line IV-IV in FIG. 1.

Fig. 1 shows a device according to the invention in side view. The device is used to produce a bulge on a strand made of steel wire, which - however in finished form - is indicated by dashed lines in FIG. 1. The device consists of a frame 10 made of white parallel side cheeks 11, which are connected at one end by a cross-connecting tube 14 and at the other end by an end plate 15. On the outer surfaces of the side walls 11, a bracket 60 is fastened, which consists of a screwed base plate 63, to which a handle 61 and a foot 62 are attached.

At the left end of the side cheeks 11 in the illustration in FIG. 1, a clamping device 20 with two clamping jaws 22 is fastened exchangeably by means of continuous bolts 27. This type of attachment allows different materials to be used and, in the event of any damage or soiling, the entire clamping device 20 can be replaced quickly. In the interior of the clamping device 20, an opening mechanism is indicated by dashed lines, which essentially consists of two compression springs 24, which press on two pins 28 ′, which are each attached to one of the clamping jaws 22. The exact design and the mode of operation of the clamping device 20 are explained in more detail below with reference to FIG. 2.

At the opposite end of the side walls 11, slideways 12 are provided along their upper and lower longitudinal edges, on which a sliding carriage 30 arranged between the side walls 11 can be displaced. The slideways 12 can, as shown, be formed on the side cheeks 11 themselves; but they can also be formed on special slide rails, which are then attached to the longitudinal edges of the side cheeks 11. The slideways are overlapped by slide strips 36 which are arranged on the slide carriage 30.

On the sliding carriage 30 there is a pressure piece 31, by means of which the axial pressure required for the compression of the strand can be exerted. The pressure piece 31 has a blind hole 34 into which the end of the strand to be compressed which is combined by a sleeve is inserted. The blind hole 34 continues into a central bore 33 with a smaller diameter, into which the central wire of the strand runs during the upsetting process. The depth of the central bore 33 can be adjusted with the help of an adjusting screw 35 with lock nut 37 as required.

On the underside of the slide carriage 30, a double-acting cylinder-piston unit 40 is articulated via an axis 32, the piston rod 41 of which is operatively connected to one end 45 of a two-armed lever 42. The lever 42 is pivotally mounted on the side cheeks 11 via an axis 43. Its end 44 opposite the piston rod 41 is supported against the end faces of the clamping jaws 22 of the clamping device 20. The cross-connection tube 14 also serves as a stop for limiting the pivoting movement of the lever 42, provided that this is not limited by the stroke of the cylinder-piston unit 40.

A longitudinal slot 13 is also provided in each of the side cheeks 11 of the frame 10. In this longitudinal slot 13 a sliding device 51 is slidably guided, to which the compression tube 50 is attached. Between the sliding device 51 and the sliding carriage 30, both of which are displaceable on the side cheeks 11 but also against one another, there is a frictional engagement which ensures that the sliding carriage 30 takes the compression tube 50 with it when it moves back to the starting position shown in FIG. 1 after the production of a bulge on a strand. The upsetting tube 50 can also be pushed back into the starting position by hand.

The construction and mode of operation of the clamping device 20 can be explained with reference to the top view according to FIG. 2. Each of the two movable clamping jaws 22 is pivotally supported against a fixed counter jaw 26 by a number of toggle levers 21 arranged parallel to one another and in a row next to one another. The clamping jaws 22 and the counter jaws 26 have circular-arcuate recesses 25, against which the likewise circular-arc ends of the toggle levers 21 roll. In this way, the clamping forces, which are very large due to the almost right-angled arrangement of the toggle levers 21 with respect to the direction of movement of the clamping jaws 22, can be removed in a particularly gentle manner. Axle bolts 28 additionally arranged serve only to ensure the pivoting and opening function in the opened state of the clamping jaws 22.

The movement of the jaws 22 is limited by an adjustable stop 23. As a result, the clamping force acting transversely to the strand can be metered exactly, so that both slipping of the strand due to insufficient clamping force and damage to the strand due to excessive clamping pressure can be avoided.

As far as possible, the toggle levers are covered by cover plates 29 in order to keep contamination and the risk of injury low and to prevent the toggle levers 21 from falling out.

The clamping force required to clamp the stranded wire is generated by retracting the piston of the cylinder-piston unit 40 and transmitted directly to the clamping jaws 22 as an axial force via the two-armed lever 42. The lever ratios are chosen so that at the beginning of the work cycle the jaws 22 are first closed against the braid until they abut the stop 23 with their rear end faces. Only then is the sliding carriage 30, which until then was held back in the axial direction by the stiffness of the strand, pulled with the pressure piece 31 against the clamping device 20, as a result of which the strand begins to bulge.

3 shows a view of the end face of the device in the area of the clamping device 20. Two semicircular recesses can be seen in the mutually facing side surfaces of the clamping jaws 22, which receive the strand to be compressed. Furthermore, the cross-connecting tube 14 can be seen, which serves at this end of the device for connecting the side cheeks 11 to the frame 10 and at the same time as a stop for the movement of the lever 42 when the clamping device 20 is opened after the bulge has been completed. The fork-shaped lower end 45 of the lever 42, to which the piston rod 41 is connected in an articulated manner, can also be seen. The piston rod itself, the cylinder-piston unit, the compression tube and the holder are omitted in this illustration in order to increase clarity.

Fig. 4 shows a cross section along the line IV-IV in Fig. 1. It can be seen on the bracket 60 attached to the side panels 11 with the base plate 63, the foot 62 and the handle 61. Between the side panels 11 and this above and below with the aid of slide rails 36, there is the slide carriage 30 with the axis 32 for fastening the cylinder-piston unit 40. Furthermore, the compression tube 50 with a rotatable inner tube 52 can be seen. In the direction of view behind the compression tube 50, the pressure piece 31 with the blind hole is located 34 and the central bore 33.

To produce a bulge on a strand, with the piston rod 41 extended, a strand is inserted from above into the jaws 22 of the clamping device 20 opened by the springs 24 and the end of the strand provided with a sleeve is inserted into the blind bore 34 of the pressure piece 31. Then the piston rod 41 of the cylinder-piston unit 40 is retracted; the upper end 44 of the lever 42 lies against the end faces of the clamping jaws 22 and moves them in the direction of the stop 23. As a result of the parallel guidance of the movable clamping jaws 22 by means of the toggle levers 21 supported against the fixed counter-jaws 26, the clamping jaws fix themselves around the Strand and hold it immovably and damage-free. By appropriate selection of the length of the clamping jaws 22 and the toggle lever 21 and adjustment of the stop 23, the clamping pressure on the strand can be kept low despite the high holding effect. The upsetting pipe 50 is located at its left stop in the illustration in FIG. 1 or in any case in the vicinity thereof.

When the piston rod 41 is retracted further, the sliding carriage 30 with the pressure piece 31 is pulled in the direction of the clamping device 20. The strand comes under axial compression pressure, so that its wires bulge. The wires lie against the upset tube 50 or the rotatable inner tube 52 from the inside and, as the upset continues, they obtain the desired permanent shape of the bulge there.

After the bulge has been produced, the piston rod 41 is moved out of the cylinder-piston unit 40 again, the sliding carriage 30 being returned to its right-hand starting position. In this position, the finished bulge is indicated in dashed lines in FIG. 1. If there is a frictional connection between the sliding device 51 with the compression tube 50 and the sliding carriage 30, this is also taken along when the sliding carriage 30 is returned; the upsetting tube 50 can also be pushed back by hand.

If the stroke of the cylinder-piston unit 40 does not previously limit the path of the two-armed lever 42, this comes to rest on the cross-connection tube 14. This eliminates the closing pressure on the jaws 22 so that they can open again under the action of the springs 24 of the opening mechanism. The deformed strand with the bulge can then be easily be lifted up out of the device.

Before the next deformation process begins, only the upsetting tube 50 has to be brought back by hand to its stop adjacent to the clamping device 20. All other processes run automatically as described and only controlled by the cylinder-piston unit 40.

Claims (15)

1. An apparatus for forming, as an anchoring in concrete structural members, a bulge at the end of a strand of steel wires, wherein the strand is axially compressed at its free end over one portion of its length and, therefore, the individual wires are axially deformed and spread apart, comprising a frame (10), there being provided at one end of the latter a clamping device (20) with two clamping jaws (22) and at its other end a pressure member (31) displaceable via a double-acting piston-cylinder unit (40), while a compressing tube (50) mounted displaceably in a longitudinal direction is provided therebetween, both the pressure member (31) and the compressing tube (50) having means enabling the strand to twist freely while being compressed, characterised in that the frame (10) has two lateral cheeks (11) which are maintained at a mutual distance apart and which at one of their ends support the clamping device (20) and on the other ends of which a slide carriage (30) is displaceable which, at one end, carries the pressure member (31) and to which, at the other end, the piston-cylinder unit (40) is fastened, in that the clamping jaws (22) are guided parallel to fixed counter jaws (26) by means of toggle levers (21) arranged in rows, and in that a two-armed lever (42) is pivotably mounted on the frame (10), one end (45) of which lever is in operative connection with the piston-cylinder unit (40), whereas its other end (44) bears against the end faces of the clamping jaws (22).

2. An apparatus according to Claim 1, characterised in that slideways (12) for the slide carriage (30) are provided on the longitudinal edges of the lateral cheeks (11).

3. An apparatus according to Claim 2, characterised in that the slideways (12) are formed on slide rails.

4. An apparatus according to any one of Claims 1 to 3, characterised in that the slide carriage (30) is displaceable between the lateral cheeks (11) and overlaps the slideways (12).

5. An apparatus according to any one of Claims 1 to 4, characterised in that a longitudinal slot (13) is provided in each of the lateral cheeks (11), a slide device (51) for the compressing tube (50) being guided in the slot (13) in the manner of a slotted link.

6. An apparatus according to Claim 5, characterised in that frictional contact takes place between the slide device (51) for the compressing tube (50) and the slide carriage (30).

7. An apparatus according to any one of Claims 1 to 6, characterised in that the clamping device (20) is provided with an adjustable stop (23) for the clamping jaws (22).

8. An apparatus according to any one of Claims 1 to 7, characterised in that the clamping device (20) is provided with an opening mechanism for the clamping jaws (22).

9. An apparatus according to Claim 8, characterised in that the opening mechanism has a respective spring member, preferably a compression spring (24), which via a pin (28'), presses the respective clamping jaw (22) in the opening direction.

10. An apparatus according to any one of Claims 1 to 9, characterised in that the clamping jaws (22) and the fixed counter jaws (26) have recesses (27) of circular-arc shape and the toggle levers (21), which are likewise of circular-arc shape at their ends, bear in articulated manner against the recesses (27).

11. An apparatus according to Claim 10, characterised in that the toggle levers (21) are additionally mounted by means of pivot pins (28) on the clamping jaws (22) and/or on the counter jaws (26).

12. An apparatus according to any one of Claims 1 to 11, characterised in that the pressure member (31) has a bore (33) to accommodate the central wire of a strand, the depth of the bore being adjustable.

13. An apparatus according to Claim 12, characterised in that a setscrew (35) is provided to adjust the depth.

14. An apparatus according to any one of Claims 1 to 13, characterised by the provision of a mounting (60) with a handle (61) and a base (62), which mounting is secured externally to the lateral cheeks (11).

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