WO1994025213A1

WO1994025213A1 - Process and device for producing steel fibres

Info

Publication number: WO1994025213A1
Application number: PCT/DE1994/000404
Authority: WO
Inventors: Boris Evseev; Wilhelm Kämereit
Original assignee: Mannesmann Ag
Priority date: 1993-04-26
Filing date: 1994-04-11
Publication date: 1994-11-10
Also published as: AU6502094A; DE4314008C2; DE4314008A1

Abstract

To reduce the production cost of steel fibres for fibre concrete by shredding steel strip it is proposed that, in order to obtain a longer length of fibre than the width of the steel strip, the cut, viewed in the plane of the steel strip, is made obliquely at a (cutting) angle of 15° to under 90° in the feed direction of the strip. The invention also relates to a device for implementing the process in which the cutting device (1) can pivot in relation to the feed device (4) about an axis which is perpendicular to the feed direction and the axis of rotation (5).

Description

Method and device for producing steel fibers

The invention Detnfit a procedure for the production of steel fibers for fiber detonate according to the preamble of claim I and one

Device for carrying out this procedure.

From SU 10 54 517 is a generic procedure and one

Device for steel manufacturing known. This device has a cutting device which consists of a plurality of rotating knife devices arranged in parallel next to one another in the form of a knife roll. The individual knife devices each have one

disc-shaped basic body, which is equipped with a large number of cutting edges on its circumference. The cutting device is driven by an electric motor. Furthermore, the cutting device has a cutting edge parallel to the axis of rotation of the knife device

arranged static knife. Finally, this known device also has a feed device in the form of a motor-driven conveyor roller pair with which steel strip can be fed to the cutting area of the knives at a defined feed rate. The steel strip used as the insert material on this device has a width which is approximately the width of the entire knife roll

corresponds. The cutting movement of the rotating knives results in a large number of steel fibers, the length of which corresponds to the respective width of the disk-shaped knife base body. Steel strip is thus cut into steel fibers, the length of which is one of the number of

Knife blades corresponding to the fraction of the original

Steel bandwidth corresponds.

This known device supplies steel fibers in a form corresponding to the respective specification, since steel strips of different thicknesses can be used and the feed rate to achieve a certain cutting line, the speed and number of cutting edges of the knives can be adjusted, so that fibers of a defined height and thickness are produced. The fiber rod is selected by the particular one

Cutting width determined. The disadvantage here, however, is that as

In any case, the operational material is a comparatively high quality

Tape material must be used, which drives up the manufacturing costs.

From JP 58-28047 B a Vertanren for the production of steel fibers is known, which decays in a similar manner. In the subscmed to the above-mentioned method, however, several become narrow

Steel strip parallel to the cutting device, which in principle consists of a rotating cylinder designed as a solid cylinder

Knife device and again a test knife. The fiber length is determined by the width of the strips fed in each case. In order to bring the thickness and length of the fibers into a predetermined ratio, the thickness and width of the tapes used must always satisfy this ratio. The

Depth of cut can be adjusted by adjusting the feed speed and the Rotation speed of the cutting edges of the cutting device can be set to values which correspond to the desired ratio. Ruch with this verτarιren is the disadvantage that relatively high-quality material with defined dimensions must be used, so that the manufacturing costs are correspondingly high.

The invention is therefore to improve a generic method in such a way that the production costs for the steel fibers are reduced, and to provide a suitable device for carrying out this method.

This courage is resolved with regard to the method by the characterizing features of patent claim 1

Embodiments of this method are characterized by the features of

Subclaims 2 - 6 marked. A device according to the invention advantageously has the features of patent claim 7

Embodiments of this device are specified in subclaims 8 to 18.

The starting point of the present invention was the consideration that

Manufacturing costs dadurcn to lessen that a substantial

less expensive material can be used than is the case with Disner. It should be possible to use other material which is considerably narrower than the usual one and, if possible, even represents an abt al product, such as, in particular, residues of soaltband uno

Band seam material from hot or cold strip production. On the previously known system, the processing of such material would be in

hardly possible in a meaningful way and would often lead to non-smokable fibers, especially if relatively narrow strips are to be processed, the width of which is smaller than the desired fiber length. The

Fiber geometry must meet certain minimum requirements. This also includes a minimum ratio of the fiber length to the smallest transverse dimension of the fiber. For smooth fibers this ratio must be over 100, for profiled or curved fibers this value can also be lower (eg 80).

The invention makes it possible to still produce fibers of this length from tape material whose width is less than the desired fiber length by not making the cut exactly perpendicular to the length as before

Feed direction of the tape, but at an acute angle,

in particular at an angle of less than 90 and about 15 to the feed direction. For this purpose, the device according to the invention has been modified in such a way that the

Cutting device overall compared to the feeding device Tur the steel strip is designed to be pivotable about a vertical axis, so that the required oblique setting is adjustable. The

Feeding device can advantageously be set up for the simultaneous feeding of several parallel belts. In such a case, it is not the thinnest but the thinnest of these bands that is decisive for the inclination to be selected. In the case of irregularly wide bands (e.g. trimmed bands), the narrowest band points must be taken into account. The slanting of the cutting device is to be chosen so that the resulting smallest fiber length in relation to the strip thickness becomes sufficiently large. Feed speed,

Number of cutting edges on the knife device and speed of the

Knife devices are to be set up in such a way that there is a cut rivet which also fulfills the desired minimum relationship to the fiber length.

The invention can also be used with advantage if that

Cutting out of a wider steel band is to be done using a cutting tool directly from other men side by side, coaxially arranged knife disks is formed, the width of which corresponds to the fiber length. By the inventive

Sloping guidance of the steel strip can also be used in the insert material, the width of which is significantly smaller than the total width of all

Knife disks, without individual knife disks, as would have been inevitable with the conventional vertical feeding of the 5-steel strip, had to run empty and a corresponding reduction in the

Production output would be taken in chewing.

The guiding of the cut at an oblique angle (cutting angle) to the tape feed direction has proven to be extraordinarily advantageous when cutting narrow tapes for another reason. The smaller the cutting angle, the more the ends of the individual fibers are sharpened. In contrast to blunt (cut angle 90) cut fibers, fibers with pointed ends avoid or at least reduce the creation of inadmissible stress peaks during the transfer of stresses between the fiber and the adhering concrete. Therefore, the formation of micronuts in the concrete mass, which can otherwise be found regularly due to the volume shrinkage when setting the concrete, can be drastically reduced when using fibers manufactured in accordance with the invention and often even completely suppressed cutting angles in the range of 20-60 °, in particular in the range of 30 -40º have proven to be very useful in practical implementation.

A very particularly advantageous form of the fibers can be produced by using a cutting device for carrying out the process according to the invention, which has two cutting edges which are moved directly past one another during cutting, at least one of which, preferably a test knife, has one in the area of its cutting edge Pure notches are spaced apart the depth and width of which preferably increase towards the cutting edge. The width and depth of the notches, for example for fibers of 0.5-1 mm in thickness, are expediently of the order of magnitude of 1-2 mm, and their spacing between them is 2-4 mm. The notches result in a very favorable, irregular surface, with the longitudinal extension of the individual fibers remaining unchanged in a straight line, that is to say a changing cross-sectional shape over the length of the fibers, the cross-sectional area remaining constant when one disregards the pointed end regions of the fibers. The individual fibers can be twisted about the longitudinal axis. Through the strong achieved

With surface protection, the concrete has excellent adhesion to the fibers and therefore very good tension transmission.

because of the constant cross-sectional area and the consequent constant resilience of the fibers can be minimized

Use of fiber material to achieve maximum tensile strength in concrete. It should be borne in mind that by the

Strong deformation occurring in fiber production can also achieve a considerable strain hardening in the fibers.

The particularly good adhesion of the concrete to the profiled fibers makes it possible to significantly increase the length of the fibers compared to smooth fibers

Reduce. The ratio of fiber length to fiber thickness can therefore be reduced to values below 80 and even below 50 without loss of strength in the finished fiber concrete. A practical range for this ratio can be given as 30-50. The choice of smaller network values, in particular values below 50, has the great advantage of processing the fibers in the concrete mix that the so-called hedgehog formation, i.e. the training of

Lumps of fibers due to the interlocking of individual fibers can be practically completely avoided. With regard to the inhibition of crack formation in the concrete, the fiber weight introduced into the concrete per unit volume is not so important, rather it is important that the total surface of the introduced fiber material is as large as possible in order to be able to absorb the shear stresses effectively. Therefore, the largest possible ratio of fiber surface to fiber weight should be aimed for in order to achieve the greatest possible effect with as little fiber material as possible. In this regard, the invention has significant advantages.

Due to the oblique cutting angle, it can be easily cut

Process steel strips with a width of less than 25 mm into high-quality fibers. Even with a bandwidth of only 5 mm, a sufficiently small cutting angle (e.g. 15 - 20 °) can still produce satisfactorily long fibers with a suitable thickness (e.g. 0.5 mm). A favorable sheet width is in the range 10 - 20 mm.

Based on the embodiment shown in the drawing, the invention is explained in more detail below. Show it:

FIG. 1 shows a top view of a device according to the invention,

FIG. 2 shows a side view of this device,

FIG. 3 shows the belt running side of this device,

Figure 4 is a knife roll and

Figure 5 is a stationary knife with notches.

The machine shown in FIGS. 1 to 3 in different views has a machine housing 14 standing on a base plate 15, which is covered at the top with a table top 21. Aut der Table top 21 has a feed device 4 fixedly arranged in the present case only for processing a single narrow steel band 13 (eg band seam material). The steel strip 13 is fed by a pair of conveyor rollers, of which only the upper conveyor roller 12 can be seen in FIG. 1 and via the

Electric motor 6 and the bevel gear 7, preferably a

Worm gear, is driven with a fixed or adjustable feed speed. Side guides 22, 23 for the steel strip 13 are arranged in front of and behind the conveyor roller 12. With a wider design of the pair of conveyor rollers and corresponding adjustment of the side guides 22, 23, it was also possible to feed several narrow steel strips at the same time. A cutting device 1 is arranged transversely to the strip inlet direction in the strip inlet direction behind the side discharge 22. This essentially consists of the rotating disc-shaped

Knife device 2, a storage 9 tur the axis of rotation 5

Knife device 2, a second electric motor θ and one

Belt transmission 10, 11 for changing the drive speed of the

Knife device 2. In the storage 9 can if necessary

Intermediate gear must be installed. The rotating knife device 2 is equipped with a plurality of cutting edges 20 on the circumference of the disk-shaped base body. If the machine was designed for the simultaneous processing of several parallel steel strips, the knife device 2 would be correspondingly wider and would preferably consist of several knife disks arranged next to one another or of a corresponding one-piece knife roller 24 (FIG. 4), in which the cutting edges 20 span the entire roller width announced. As a further essential element, the cutting device 1 has a test knife, ie a stationary knife 3, which, in cooperation with the knife device 2, cuts the strip 13. The whole

The cutting device 1 is mounted on a carriage 25 which can be pivoted horizontally on the table top 21 in BogenTuhrungeπ 17, so that any angular positions of the rotary axis 5 for Belt entry direction, preferably adjustable in the range from 90 to 15 and can be fixed by means of screw connections. The of the

Steel fibers produced by the cutting device 1 fall down onto a chute 15 and can enter a collecting vessel (not shown). The knife device 2 is covered (FIG. 2) on the outside by a sheet metal housing 18 which is provided with a flap 19 in order to enable the knife device 2 to be replaced easily. For example, knife devices of the same diameter can also be used

different number of cutting edges one under otherwise constant

Conditions can be set according to changed fiber width. The larger the number of cutting edges, the smaller the fiber width. By increasing the speed of the knife device 2, a reduction in the fiber width can also be brought about, as can a reduction in the feed speed. It is of course also possible to use the cutting device 1 for parallel processing of several e.g. to equip belts of different thicknesses with several knife devices with different number of cutting edges. The fiber length is changed via the inclination of the axis of rotation 5 to the tape inlet. The smaller the angle, which is 90 ° in FIG. 1, the longer the fibers become. It is recommended to cut the individual cutting edges in a manner known per se to the drainage socket 5 from the basic body of the

To arrange knife device 2. As a result, fibers can be produced which are twisted around the longitudinal axis. The maximum length of the

The fibers that can be produced depend on the width of the knife roller or knife disk. Depending on the width of the insert

Steel strip goes out, the greater is the range of variation of the fibers that can be produced from this steel strip, depending on the inclination.

FIG. 5 shows a particularly advantageous embodiment of a stationary knife 30, which is designed in the form of an interchangeable plate and is inserted into the device according to FIGS. 1 to 3 of the stationary knife 3 used there can be used. That knife

30 has a total of 4 notches 32 in the area of its cutting edge 31, which are in the direction of tape feed, that is to say in the direction of the cutting edge

31 increase in depth and width, when the movable knife device interacting with the stationary knife 30, which is not shown in FIG. 5, moves past the cutting edge 31, the sheet metal strip lying flat on the stationary knife 30, which is not shown in edenTalls, printed in the notches and plastically deformed, so that a profiled surface is created on the fibers produced. Instead of a notched stationary knife, it was also possible to use movable knife devices with corresponding notches on their cutting edges in order to achieve the desired profiling. However, the required tool wall would be correspondingly higher. It goes without saying that, in principle, notches on the stationary knife and on the movable knife device of the cutting device can also be provided at the same time. Due to the high wear resistance, the use of hard metal blades is recommended.

Example 1:

There is a band with a width of 15 - 20 mm and a thickness of 0.3 mm. Fibers with a length of at least 23 mm and a width of about 0.3 mm are to be produced, with the length / width ratio being at least 80. For this purpose, a device according to Figure 1-3 is used, in which the angle between the

Cutting direction and the feed direction was changed from originally 90 (FIG. 1) to 39 °. This results in a fiber length of 15 mm / sin 39 ° to 20 mm / sin 39 °, i.e. 24 - 32 mm. At a

5chneιdenzahl of 12 and a speed of the knife device of 1000 min, for example, a feed rate of 3600 mm / min set. This results in consideration of the

Inclination of the cutting device the desired "cutting depth" (fiber width) of 0.3 mm. The fibers obtained are each twisted about their longitudinal axis and have pointed ends with a tip angle that is between the selected setting angle

Cutting device and feed direction corresponds.

Example 2:

In a manner similar to that in Example 1, a sheet of 0.5 mm thickness and 15 mm width was processed on a system whose stationary knife was provided with 5 notches in the cutting edge. The cutting angle was set to 37 so that a fiber rod of 25 mm resulted. The 5chnιttιeτe was set according to the sheet thickness also 0.5 mm. The fibers produced in this way were straight in the longitudinal direction and had a strongly profiled surface and very pointed ends.

This extremely simple construction means that very inexpensive input materials, which are to be regarded as waste materials, can be turned into a high-quality product in a cost-effective manner

to process. One advantage of using edging tape is one that corresponds to the variable width of the insert material

Mix of fibers of different lengths.

Claims

Process for the production of steel fibers for fiber reinforced concrete

Cutting steel strip,

characterized,

that to achieve a fiber length that is larger than the

The width of the steel strip used corresponds to the cut - as seen in the steel strip plane - at an angle at an angle

(Cutting angle) from 15 ° to less than 90 ° to the tape feed device, the method according to claim 1,

characterized,

that a cutting angle in the range 20-60 °, especially in the range

30 - 40 is set.

The method of claim 1 or 2,

characterized,

that the cut is carried out with a cutting device which has two cutting edges which move directly past one another during cutting, at least one of which has a plurality of notches in the region of its cutting edge, into which the

Fibers to be cut are pressed in when cutting with plastic deformation.

Method according to one of claims 2 or 3,

characterized,

that a steel strip with a width in the range of 5 - 25 mm, in particular in the range of 10 - 20 mm is used. Method according to one of claims 3 or 4,

characterized,

that the cutting angle taking into account the width of the

Steel strip and the feed of the steel strip (distance between two immediately adjacent cuts) so to each other

be set so that the ratio of fiber length to

Fiber is less than 80, especially less than 50.

Method according to claim 5,

characterized,

that a ratio of fiber length to fiber width in the range of 30

- 50 is set.

Device for carrying out the method according to claim 1, comprising a cutting device (1) with a rotating knife device (2) working against a stationary knife (3, 30) and driven by a motor (9) and with one driven by a motor (6) Feed device (4) for

continuous feeding of steel strip (13) into the cutting area of the cutting device (1), the axis of rotation (5) of the rotating knife device (2) being arranged transversely to the feeding direction of the steel strip (13),

characterized,

that the cutting device (1) relative to the feed device (4) is arranged pivotably about an axis which is perpendicular to the

Tape feed direction and to the axis of rotation (5).

Device according to claim 7,

characterized,

that the pivotability over an angular range of 30 to 90 based on the angle between the axis of rotation (5) and the feed direction of the steel strip (13). Device according to claim 7 or 8,

characterized,

that the feed speed of the drive of the feed device (4) can be set to different values. Device according to one of claims 7 to 9,

characterized,

that the speed of the cutting device (1) can be set to different values. Device according to one of claims 7 to 10,

characterized,

that knife devices (2) with different numbers of cutting edges (20) distributed over the circumference can be used as cutting device (1). Device according to one of claims 7 to 11,

characterized,

that the cutting device (1) has a plurality of rotating knife devices arranged coaxially next to one another. Device according to one of claims 7 to 12,

characterized,

that as a rotating knife device (2) a knife roller (24) is provided, the cutting of which over the entire length of the Knife roll (24) and each make up a multiple of the width of the steel strip (13) to be used, and that the

Feed device (4) is set up for the simultaneous parallel feeding of several individual belts. Device according to one of claims 7 to 13,

characterized,

that the cutting edges (20) of the knife device (2) at an angle to

Axis of rotation (5) are aligned. Device according to one of claims 7 to 14,

characterized,

that the cutting edges of the knife device (2) and / or the cutting edge of the stationary knife (30) has a plurality of notches (32) in the region of the cutting edge (31). Device according to claim 15,

characterized,

that the notches (32) are arranged only on the stationary knife (30) and have increasing width and width in the tape feed direction. Device according to one of claims 7 to 16,

characterized,

that the cutting of the knife device (2) and / or the

stationary knife (3, 30) are formed from a hard metal. Device according to one of claims 7 to 17,

characterized,

that the cutting edges of the knife device (2) extend significantly beyond the width of the steel strip (13).