EP1113111B1 - Concrete breaking shear - Google Patents

Abstract

The pliers have hinged jaws (1,2) moved using hydraulic cylinders. The first jaw has a frame body (6) with first breaking and cutting areas. The second jaw has a body (7) with second breaking and cutting areas. When the pliers are closed, the second jaw fits in the first jaw and the breaking and cutting areas co-operate. The cutting areas have cutting elements (17,20), which are releasably fixed in holder pockets in the jaws.

Description

The present invention relates to a concrete crusher according to the preamble of claim 1.

Such concrete crushing tongs are used to break off structures made of reinforced concrete. Here it is particular desirable that the pliers move the concrete crusher on the one hand the concrete is broken and on the other hand in the same sequence of movements the reinforcing iron is cut. This means that the demolished material can be shredded without an additional operation, such as cutting of rebars with a cutting torch if this is not in optimal Cut through the concrete crusher, a crusher for Further processing can be carried out, in which a separation of concrete and metal is done.

Such concrete crushing tongs are known. For example, in a concrete crusher is shown in US-A-5 183 216. This In addition to the breaking teeth, concrete crushing pliers also include cutting elements, which are held in rectangular recesses. When cutting the Reinforcing irons are exposed to high loads on these cutting elements. This can cause areas of the rectangular recesses to be excessive be loaded, which can result in deformation. this leads to Damage to the recesses, which is due to extensive repair work to fix.

WO-A-96/02708 shows a concrete crushing tongs according to the preamble of the independent claim, the two Pliers jaws, each with concrete crushing areas and Cutting edges are provided. The concrete crushing areas are over the Cutting edges protruding, which is to avoid breaking of the concrete is triggered by the cutting edges used to cut the Reinforcing iron are provided and therefore have a relatively sharp edge should. The breaking edge and the cutting edge are all-round, i.e. In order to be able to optimally cut the reinforcing bars, the concrete breaking edge may do not protrude too much beyond the cutting edge. This allows do not avoid the cutting edge by breaking the concrete is heavily used, which can result in severe wear and tear expresses itself in declining cut quality for the reinforcing iron.

Because the cutting edges are high when cutting the reinforcing iron The corresponding cutting elements must be subjected to tensile and compressive forces optimally connected to the corresponding jaw his. With this concrete crusher described above, this becomes achieved that the material forming the cutting edge on the pliers jaw is welded on. However, this has the disadvantage that when worn Cutting edge new material has to be welded on, which is usually the case takes place in a workshop, whereby the pliers are not in operation for some time and thus large dead times arise. Furthermore, more cannot be done as often Material to be welded onto the jaws of the pliers because of the heating Structural changes in the material result, which also the Strength of this material and thus the connection between welded Material and pliers jaw is no longer optimal and break out can.

The object of the present invention is now a To create concrete crushing pliers, in which the renewal of the cutting edges can be carried out without long downtimes of these pliers, and in which an optimal refraction of the concrete is achieved.

According to the invention, this object is achieved by the Claim 1 listed features.

With the possibility that the cutting elements of the concrete crusher can be exchanged, which is practical at the place of use of this concrete crusher long downtimes can be avoided.

Here are first cutting elements, each of one with a Bend block are formed on the side areas of the first Pliers jaw and the second pliers jaw attached. Thereby lies convex surface in the provided with a corresponding support surface Pocket of the pliers jaws on their concave surface with those lying in a plane perpendicular to the swivel axis Side faces each form a cutting edge. In addition to the advantage that these individual blocks can be replaced very quickly, also achieved that the absorption of forces when cutting the reinforcing iron and their transfer to the jaws in an optimal way can be done.

Another advantageous embodiment of the invention consists in that a guide rib on the convex surface of the previously described block attached, which is aligned in the longitudinal direction to the convex surface is and runs in the middle, the respective support surface of the receiving pocket is equipped with a groove corresponding to the guide rib, in which the guide rib in the inserted state of the block in the pliers jaw intervenes. With this device, the block is optimally in the pocket of the respective jaws.

Another advantageous embodiment of the invention consists in that elements at the end regions of the support surfaces of the receiving pockets are attached, which are provided with stop surfaces on which the End faces of the blocks are in the inserted state in the receiving pockets are. As a result, these blocks are optimally held in the pockets, since the blocks themselves are not, for example with screws, with the pliers jaw connected, arise from those occurring during the cutting process Forces no excessive voltage peaks, for example, to Breakage of the screws could result in optimal forces in the jaw of the pliers can be transferred.

Advantageously, the jaws on each side area two each arranged in series, formed by the blocks Cutting elements are provided, which can be screwed onto the pliers jaw Teeth are kept in the receiving pockets. The tips of the teeth are protruding beyond the cutting edges of the cutting elements, causing breakage of the concrete is at least introduced through these teeth and the Cutting edges are thus protected.

Another advantageous embodiment of the invention consists in that the bend of the block forming the cutting elements is circular is, which makes the contact surface optimal and the production of the blocks and the Recording bags is simplified. The one between the two cutting edges lying concave surface of the blocks has a curvature and the wedge angle the cutting edge becomes larger than 90 °. When cutting the reinforcing iron if this is first on the curvature, it is squeezed before the cutting edges engage, which in turn protects the cutting edges become. Due to the symmetrical design of these blocks, this can Block in the receiving pocket are rotated so that one of the two Cutting edges are in use, so that the material is optimally used.

Another advantageous embodiment of the invention consists in that on the frontal area of the first and second jaws of each a plate forming the second cutting element is attached, each with a side surface on a corresponding support surface of the receiving pocket rests and thus optimal power transmission to the jaws is achieved becomes.

The back of this plate is supported on the support surface adjacent wall of the first jaw or the second jaw and is screwed against it. So this plate is also easier Way interchangeable.

The two side surfaces of the plate are advantageously provided with indentations and protrusions along which the cutting edge runs. The plate can be inserted into the receiving pocket in such a way that one or the other of the two cutting edges is in use. Also in this way the material is optimally used.

Another advantageous embodiment of the invention consists in that the plate between the two front teeth of the first and the second pliers jaw is arranged, the tips of the teeth over the Cutting edge of the plate are protruding. This will break the concrete in turn at least initiated via the teeth, the cutting edge of the This protects the plate.

So that the concrete is broken in an optimal way and the Cutting edges of the cutting elements are protected on the second Pliers jaw additional teeth attached between each pair forming teeth are arranged and protrude beyond their tips. Thereby is achieved when the reinforced concrete breaks off through the pliers area is first subjected to bending and thus the concrete breaks more easily.

The teeth are advantageously arranged in the jaws of the pliers in such a way that when the pliers are closed, the back teeth on the impact the concrete part to be broken off and the concrete is broken in this area and only then engage the front teeth. This will make it Breaking the concrete easier.

An embodiment of the present invention is as follows explained in more detail by way of example with reference to the accompanying drawing.

Fig. 1 in räumlicher Darstellung eine Ausführungsform der erfindungsgemässen Betonbrechzange;

Fig. 2 eine Seitenansicht der ersten Zangenbacke mit den darin einzusetzenden ersten Schneidelementen und den Zähnen;

Fig. 3 eine Teilansicht auf die ersten Schneidelemente, die sich in einer Position unmittelbar vor dem Schneiden eines Armierungseisens befinden;

Fig. 4 eine Schnittdarstellung entlang Linie IV-IV durch die ersten Schneidelemente gemäss Fig. 3;

Fig. 5 eine der Schnittdarstellung gemäss Fig. 4 entsprechende Schnittdarstellung, wobei sich die ersten Schneidelemente in einer Position des Durchschneidens des Armierungseisens befinden;

Fig. 6 eine Draufsicht auf die die zweiten Schneidelemente bildenden Platten, die sich in einer unmittelbar vor dem Durchschneiden des Armierungseisens stehenden Position befinden;

Fig. 7 eine Schnittdarstellung entlang Linie VII-VII durch die in Fig. 6 dargestellten zweiten Schneidelemente;

Fig. 8 eine Schnittdarstellung durch die zweiten Schneidelemente gemäss Fig. 7, wobei sich diese Platten in einer Position während des Durchschneidens des Armierungseisens befinden;

Fig. 9 in schematischer Darstellung die geöffnete Betonbrechzange, die während des Schliessvorgangs soeben in ein armiertes Betonteil eingegriffen hat;

Fig. 10 in schematischer Weise eine Schnittdarstellung entlang Linie X-X gemäss der Situation von Fig. 9;

Fig. 11 in schematischer Darstellung die Betonbrechzange, deren Schliessbewegung im Vergleich zu Fig. 9 fortgeschritten ist;

Fig. 12 eine Schnittdarstellung durch die Betonbrechzange gemäss Fig. 11 entlang Linie XII-XII in schematischer Darstellung;

Fig. 13 in schematischer Darstellung eine Ansicht auf die Betonbrechzange, deren Schliessbewegung weiter fortgeführt wurde und die sich in einer kurz vor dem Durchschneiden des Armierungseisens stehenden Position befindet;

Fig. 14 eine Schnittdarstellung entlang Linie XIV-XIV gemäss Fig. 13 in schematischer Weise;

Fig. 15 eine schematische Darstellung der Betonbrechzange in voll geschlossenem Zustand;

Fig. 16 eine Schnittdarstellung entlang XVI-XVI gemäss Fig. 15 mit durchgetrenntem Armierungseisen; und

Fig. 17 eine Schnittdarstellung durch die zweite Zangenbacke entlang Linie XVII-XVII gemäss Fig. 2, mit dem zwischen den hinteren Zähnen angeordneten zusätzlichen Zahn.

It shows

1 shows a spatial representation of an embodiment of the concrete crushing tongs according to the invention;

2 shows a side view of the first jaw of the pliers with the first cutting elements and the teeth to be inserted therein;

3 is a partial view of the first cutting elements which are in a position immediately before cutting a reinforcing iron;

4 shows a sectional illustration along line IV-IV through the first cutting elements according to FIG. 3;

5 shows a sectional view corresponding to the sectional view according to FIG. 4, the first cutting elements being in a position for cutting through the reinforcing iron;

6 is a plan view of the plates forming the second cutting elements, which are in a position immediately before cutting through the reinforcing iron;

Fig. 7 is a sectional view taken along line VII-VII through the second cutting elements shown in Fig. 6;

FIG. 8 shows a sectional view through the second cutting elements according to FIG. 7, these plates being in a position while cutting through the reinforcing iron;

9 shows a schematic representation of the opened concrete crushing pliers which have just engaged in a reinforced concrete part during the closing process;

FIG. 10 shows a schematic representation of a sectional view along line XX in accordance with the situation in FIG. 9;

11 shows a schematic representation of the concrete crushing tongs, the closing movement of which has progressed in comparison to FIG. 9;

FIG. 12 shows a sectional illustration through the concrete crushing tongs according to FIG. 11 along line XII-XII in a schematic illustration; FIG.

13 shows a schematic representation of a view of the concrete crushing pliers, the closing movement of which was continued and which is in a position just before the reinforcing iron is cut through;

FIG. 14 shows a sectional illustration along line XIV-XIV according to FIG. 13 in a schematic manner; FIG.

15 shows a schematic illustration of the concrete crushing tongs in the fully closed state;

FIG. 16 shows a sectional view along XVI-XVI according to FIG. 15 with the reinforcing iron cut through; FIG. and

17 is a sectional view through the second jaw along line XVII-XVII according to FIG. 2, with the additional tooth arranged between the rear teeth.

As shown in Fig. 1, the concrete crusher consists of a first jaw 1 and a second jaw 2. This first jaw 1 and the second jaw 2 are connected to each other via a joint 3 and about a pivot axis 4 formed by the joint 3 from an open one Position, as shown in Fig. 1, in a closed position movable. This opening and closing of the concrete crusher takes place in a known manner Kind by hydraulic cylinder 5, for example, in Fig. 9 schematically are shown. This concrete crusher can be used in the usual way Construction machine can be attached, can be brought into any position by this be while the hydraulic cylinder 5 over one in this construction machine provided hydraulic unit can be controlled.

The first jaw 1 of this concrete crusher is through one Frame body 6 formed, which has a free passage on the inside. The second jaw 2 is formed by a body 7, which when closing the concrete crushing pliers penetrate into the frame body 6 of the first jaw 1 can.

The first jaw 1 has first concrete breaking areas that one each attached to the lateral areas 8 of the first jaw 1 rear tooth 9 and a front tooth 10 exist. The rear Teeth 9 and the front teeth 10 of the first jaw 1 are open screwed a web 11, which is attached to the outside of the frame body 6 is. This allows the rear teeth 9 and the front teeth 10 from the first jaw 1 removed and replaced or replaced become. On the lateral areas 12 of the second jaw 2 also each have a rear tooth 13 and a front tooth 14 attached serve as concrete crushing areas and on a web, not shown, the is attached to the inside of the second jaw by screwing are attached. Centered between the two front teeth 14 of the second Pliers jaw 2, an additional tooth 15 is attached. This additional Tooth 15 projects over the two front teeth, which can be reached thereby Effect will be described in detail later. It is also between the rear Teeth 13 of this second jaw 2 an additional tooth 16 attached, which is not visible in FIG. 1, but in particular is taken from FIG. 17 can be.

Each between the joint area and the rear tooth 9 and between the rear tooth 9 and the front tooth 10 of the first jaw 1, first cutting elements 17 are used, which consist of a circular arc Block 18 are formed. In the same way, between the joint area, the rear tooth 13 and the front tooth 14 of the second Pliers jaw 2 used first cutting elements 17, which consist of a arcuate block 18 are formed. On this circular arc Blocks 18 and their attachment in the first jaw 1 and the second Pliers jaw 2 will be discussed in more detail later.

At the front area 19 of the first jaw 1 and second pliers jaw 2, second cutting elements 20 are attached, which consist of a Plate 21 are formed. Also on these plates 21 will be closer later received.

As can be seen from FIG. 2, in which the second jaw 2 is shown, but the first jaw 1 is designed accordingly the first cutting elements 17 each of a circular arc Block 18. This block 18 has a convex surface 22 and can be formed in this way Receiving pockets 23 of the first jaw 1 and the second jaw 2 are used that the convex surface 22 on a corresponding Support surface 24 of the receiving pocket 23 rests. They are kept Blocks 18 in the receiving pockets 23 in each case on the end faces 25 thereof Stop surfaces 26 abut. These stop surfaces 26 are on the one hand through the rear and front teeth 9 and 10 of the first jaw 1 or 14 and 15 of the second jaw 2 formed during the stop surface 26, which lies in the area of the joint 3, on the first jaw 1 or the second jaw 2 is formed.

Advantageously, between the end faces 25 Blocks 18 and the stop surfaces 26 spring elements, not shown, for example Disc springs are used in the corresponding recesses Could find a place. The blocks would be biased in the pockets 23 held the seat between the convex surfaces 22 of the Blocks 18 and the support surfaces 24 would be optimal, even if necessary occurring elastic deformation of the first jaw 1 and / or the second jaw 2, so that no contamination of the seat could be done.

As can be seen from this figure, the first cutting elements 17 forming blocks 18 in a simple manner in the jaw 1 or 2 used and by screwing the rear teeth 9, 13, or front teeth 10, 14 attached to the corresponding jaw 1 or 2 become. A replacement of these blocks 18 can thus be carried out very quickly only the rear tooth 9 or 13 has to be removed become. The blocks 18 of the first jaw 1 and the second jaw 2 are identical. You can thus freely among each other be replaced. This is a confusion when inserting the Blocks 18 in the jaws 1 and / or 2 excluded, a different Wear and tear can be compensated for by mutual exchange become.

The cutting process with these first cutting elements 17, the formed by blocks 18 is shown in FIGS. 3-5. At the When the concrete crusher closes, the reinforcing iron 27 enters the area of the concave surfaces 28 of the blocks 18, as will be seen later. The concave surface 28 and the side surfaces 29 of the blocks 18 each form a cutting edge 30. The blocks 18 can thus in the corresponding Pliers jaw 1 or 2 are used that one or the other Cutting edge 30 for cutting the reinforcing iron is in use. The concave Surface 28 is equipped with a curvature 31, whereby a wedge angle β arises, which is greater than 90 °, preferably about 105 °.

When the concrete crusher is closed, the reinforcing iron 27 lies first on the domes 31 of the cooperating blocks 18, like this 4 can be seen. The reinforcing iron 27 is thereby held before the cutting edges 30 begin their cutting process. This will avoid that when the concrete crusher is closed further, the reinforcing iron 27 can be drawn into the cutting gap. The on the Block 18 forces are cheaper, the cutting process, as shown in Fig. 5, is done in an optimal manner, since that to be cut Reinforcing iron 27 does not have the tendency to become jammed in the cutting gap which in turn would tend to expand. As a result, the cutting edges 30 are optimally stressed, the service life the first cutting elements 17 is extended.

As can be seen in particular from FIGS. 4 and 5, each block 18 equipped with a guide rib 32 in the area of the convex surface 22, which engages in a groove 33 in the respective receiving pocket of the first Pliers jaw 1 and the second pliers jaw 2 is molded. This will an optimal mounting of the blocks 18 in the corresponding pockets the first jaw 1 and the second jaw 2 received.

As can be seen from FIGS. 6 to 8, there are the second Cutting elements 20 each from a plate 21. Each against the cutting plane directed surface 34 has a curvature so that each point of this Surface 34 from the pivot axis 4 of the concrete crusher the same distance having. The surface 34 provided with a curvature, mutually opposite side surfaces 35 form together with this Surface 34 is a cutting edge 36 in each case. Each of the side surfaces 35 in the state inserted into the jaws 1, 2 by a support surface 37 supported, the receiving pocket in the front area of the concrete crusher forms. The plate 21 is located opposite the curved surface 34 Surface on a wall 38 adjacent to the support surface 37 first jaw 1 and the second jaw 2 and is against this screwed. Thus, these plates 21, which are the second cutting elements 20 form, can be exchanged in a simple manner. Since the plates 21 are symmetrical, they can also be rotated so that the one or the other of the cutting edges 36 is in use.

As can be seen in particular from FIG. 6, the side faces 35 indentations 39 and projections 40. When closing the concrete crusher the reinforcing bars 27 are pushed into the indentations 39, and then clamped by the side surfaces 35 as shown in FIG. 7 is. When closing further, the reinforcement bars 27 are closed the cutting edges 36 are cut, the forces acting on the plates 21 which want to pull the plates together. This also applies to this arrangement the cutting gap does not widen, but the opposite happens, whereby an optimal cutting effect is achieved. Here too is the wedge angle the cutting edge is greater than 90 °, preferably about 105 °, which, as mentioned, the cutting edges are protected.

From Fig. 17 it can be seen how the additional tooth 16 in the second jaw 2 is arranged. About halfway between the two rear ones A plate 42 is attached to teeth 13 in the second jaw 2 which the additional tooth 16 is attached. As can already be seen from FIG. 1 is, the additional tooth 15 is attached to this plate 42. The additional tooth 16 stands, as can be seen in FIG. 17, via the two rear teeth 13 of the second jaw 2 in front. Also the additional one Tooth 15, as can be seen from FIG. 1, stands over the two front teeth 14 of the second jaw 2. The mode of action of each of these front teeth 14 and beyond the rear teeth 13 projecting additional Teeth 15 and 16 of the second jaw 2 in connection with the Teeth 9 and 10 of the first jaw 1 will be discussed in more detail below described.

9 to 16, the mode of operation and operation will be described below described the concrete crusher according to the invention. The concrete crusher is opened with the first jaw 1 and the second jaw 2, for example, via a concrete slab reinforced with reinforcing iron 27 41 brought, as can be seen in Fig. 9. The first jaw 1 and the second pliers jaw 2 are then turned over the hydraulic cylinders 5 the joint 3 slowly closed. The rear teeth 9 of the first jaw 1 come to bear on the concrete slab 41. The additional tooth 16, which is centered between the rear teeth 13 of the second jaw 2 is located and protrudes above this, also presses on the concrete slab 41. As can be seen from Fig. 10, this causes a bending effect on the concrete slab generated, the concrete begins to break under the bending forces that occur, as shown schematically in Fig. 10.

The closing movement of the concrete crushing tongs continues as 11 and 12 can be seen. In the area of the rear teeth 9 and 13 of the first jaw 1 and the second jaw 2 are located Concrete is broken further, the front teeth 10 of the first jaw are pressed against the concrete slab 41, the additional tooth 15 of the second jaw 2, which is located between the front teeth 14 and also above this, also causes the for this area Concrete slab 41 bends and breaks accordingly, as in Area of the rear teeth 9 and 13 is done. The broken pieces of concrete are ejected through the free opening of the first jaw 1.

The closing movement of the concrete crushing tongs continues as 13 and 14, the concrete breaking process, which in particular through the rear teeth 9 and 13, through the front teeth 10 and 14 and through the additional teeth 15 and 16 of the first jaw 1 and the second jaw 2 was almost completed. The first cutting elements 17 and the second cutting elements 20 have been little involved in the concrete crushing process and are therefore spared. The wedge shape of the teeth now causes the reinforcing iron to the area of the first cutting elements 17 is pressed, as shown in FIG. 13 is shown. When closing the reinforcing iron 27, the are located in the area of the first cutting elements 17.

Only when these first cutting elements 17 in their area have cut reinforcing bars 27, come the second Cutting elements 20 in use and cut the in this area reinforcement bars that run across those passing through the first cutting elements 17 were cut. This process takes place in the last part of the closing movement of the concrete crusher according to the invention. The projections 40 of the interacting plates 21 cause that the reinforcing iron to be cut is in the indentations 39 are pressed where the cutting takes place. This state is shown in the Fig. 15 and 16, the piece of the concrete slab gripped by the concrete crushing tongs 41 has broken out cleanly, the longitudinal and transverse reinforcement bars have been cut out. The concrete crusher can be opened and be placed at a different location of the concrete slab 41.

The material from which the blocks 18 and the plates 21 are made are made of steel with a hardness of around 58 HRC.

Due to the arrangement of the teeth and the previously described Cutting elements in the concrete crusher according to the invention is first a gradual breaking out of the concrete is achieved, then the rear part cut the reinforcing iron, after which the front part of the reinforcing iron is cut, and only then is the cut in the front Reinforcing iron located in the area of the concrete crushing tongs. Because of this step-by-step procedure with the closing force applied as usual optimal effectiveness of the concrete crushing tongs can be achieved, the Cutting edges for cutting the reinforcing bars are protected and thus the lifespan is extended. By the possibility of changing The cutting elements can use the concrete crusher if these cutting elements have too much wear and are optimally equipped again in a short time be, this replacement practically at the place of use of this concrete crusher can be done.

Claims (14)

1. Concrete-crushing pincers comprising a first pincer jaw (1) and a second pincer jaw (2) which are connected to one another via a joint (3) and are movable via hydraulic cylinders (5) about a swivel axis (4) formed by the joint (3) from an open position into a closed position, wherein the first pincer jaw (1) is formed by a frame body (6) in which first concrete-crushing sectors and first cutting sectors are disposed, and wherein the second pincer jaw (2) is formed by a body (7) on which second concrete-crushing sectors and second cutting sectors are disposed, which, during closing of the concrete-crushing pincers, while the second pincer jaw (2) penetrates into the frame body (6) of the first pincer jaw (1), co-operate with the first concrete-crushing sectors and the first cutting sectors of the first pincer jaw (1), and the first and the second cutting sectors are each formed of a cutting element (17; 20), which are inserted in receiving pockets (23) respectively affixed in the first pincer jaw (1) and the second pincer jaw (2), and are detachably fastened therein, characterised in that first cutting elements (17) are fastened to the lateral areas (12) of the first pincer jaw (1) and of the second pincer jaw (2), which first cutting elements (17) are each formed of a block (18) provided with a bend, the convex surface (22) of which rests in the receiving pocket (23) provided with a corresponding support surface (24), and the concave surface (28) of which with the lateral surfaces (29) lying in a plane standing perpendicular to the swivel axis (4) each form a cutting edge (30).
2. Concrete-crushing pincers according to claim 1, characterised in that affixed to the convex surface (22) of the first cutting elements (17) is in each case a guide rib (32) which is aligned longitudinally to the convex surface (22) and runs centrally, and that the respective support surface (24) of the receiving pocket (23) is furnished with a groove (33) corresponding to the guide rib (32), in which groove the guide rib (32) engages.
3. Concrete-crushing pincers according to claim 1 or 2, characterised in that affixed to the end regions of the support surfaces (24) of the receiving pockets (23) are elements provided with stop surfaces (26) against which the end faces (25) of the blocks (18) forming the first cutting elements (17) rest in the state inserted in the receiving pockets (23), whereby the first cutting elements (17) are held in the receiving pockets (23).
4. Concrete-crushing pincers according to claim 3, characterised in that on each lateral area (12) of the first pincer jaw (1) and of the second pincer jaw (2), first cutting elements (17) disposed two at a time in a row are provided, and that the element affixed between the two first cutting elements (17) is formed as a rear tooth (9; 13) forming the rear concrete-crushing sector, and that the element affixed to the end region facing away from the joint (3) is formed as a front tooth (10; 14) forming the front concrete-crushing sector, the rear tooth (9; 13) and the front tooth (10; 14) being screwed to the respective pincer jaw (1; 2).
5. Concrete-crushing pincers according to claim 4, characterised in that the tips of the teeth (9, 10, 13, 14) project over the cutting edges (30) of the cutting elements (17).
6. Concrete-crushing pincers according to one of the claims 1 to 5, characterised in that the bend of the block (18) forming the first cutting elements (17) is arcuate, that the concave surface (28) lying between the two cutting edges (30) has a curvature (31) and the wedge angle (β) is greater than 90°, and that the first cutting elements (17) can be so rotated that one of each of the two cutting edges (30) is in use.
7. Concrete-crushing pincers according to one of the claims 1 to 6, characterised in that second cutting elements (20) are fastened to the end-face area (19) of the first pincer jaw (1) and of the second pincer jaw (2), which second cutting elements (20) are formed substantially of a plate (21), the surface (34) of which directed toward the cutting plane has a curvature, so that every point of this surface (34) is at the same distance from the swivel axis (4), that this surface and the two opposing lateral surfaces (35) adjacent thereto each form a cutting edge (36), and that one of the two lateral surfaces (35) of this plate (21) rests on the support surface (37) of the receiving pocket corresponding to this lateral surface (35).
8. Concrete-crushing pincers according to claim 7, characterised in that the surface of the plate (21) opposite the curved surface (34) rests against a wall (38) of the first pincer jaw (1) and of the second pincer jaw (2) adjoining the support surface (37) and is screwed thereto.
9. Concrete-crushing pincers according to claim 7 or 8, characterised in that the lateral surfaces (35) of the plate (21) are provided with indentations (39) and projections (40).
10. Concrete-crushing pincers according to one of the claims 7 to 9, characterised in that the plate (21) is insertable in the receiving pocket in such a way that one or the other of the two cutting edges (36) can be utilized for cutting.
11. Concrete-crushing pincers according to one of the claims 7 to 10, characterised in that the plate (21) is disposed in each case between the two front teeth (10; 14) of the first pincer jaw (1) and of the second pincer jaw (2), and that the tips of the teeth (10, 14) project over the cutting edge (36) of the plate (21).
12. Concrete-crushing pincers according to one of the claims 1 to 11, characterised in that disposed on the lateral areas (8) of the first pincer jaw (1) and of the second pincer jaw (2) are in each case at least two teeth (9, 9; 10, 10; 13, 13; 14, 14) which co-operate with one another, and that about in the middle between two teeth (13, 13; 14, 14) at a time, forming a pair of teeth and having substantially the same distance from the swivel axis (4), an additional tooth (15 and 16, respectively) is affixed.
13. Concrete-crushing pincers according to claim 12, characterised in that the tip in each case of the additional tooth (15; 16) projects over the tips of the two teeth (14, 14; 13, 13) which form the pair of teeth and between which each additional tooth (15; 16) is affixed.
14. Concrete-crushing pincers according to claim 11 or 12, characterised in that the tips of the teeth (9, 10; 13, 14) which are affixed in each case to a lateral area (12) of the first pincer jaw (1) and the second pincer jaw (2), respectively, lie substantially on a straight line which intersects the swivel axis (4).

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