FR2744433A1 - RACING LATTE WITH CONVEXE RACLAGE AREA - Google Patents

Abstract

The invention relates to a scraper slat (1) for scraping the transported material (2) from the lower run (3) of a conveyor belt (4) by means of a scraper edge (7) which can be applied to its work surface (11). The object of the invention is to improve such a scraping slat (1) in that, together with higher scraping performance, it also guarantees a longer operating time. This object is achieved according to the invention in that the scraper slat (1) adapts to the surface contour (10) of concave section of the working surface (11) to the lower strand (3) by a convex contour. (7a) of its scraping edge (7).

Description

DESCRIPTION

  The invention relates to a doctor blade for scraping the material adhering to the lower strand of a conveyor belt and comprising a scraping edge which can

  be applied to the work surface of the latter.

  Such scraper slats are part of a scraping device for which there are two types of execution depending on the installation of the scraper batten: on the one hand the drum scraper, the scraper batten attacks the working surface of the conveyor belt at a return drum or a backing roll, and secondly the conveyor belt scraper, which is applied to the working surface of the conveyor belt in an area located behind a return drum or a backup roll, at the bottom strand. The invention relates to the latter

type of scraping devices.

  From the state of the art, scraper slats of the type mentioned in the preamble are known in many forms for scraper devices completely different from one another. German Offenlegungsschrift 27 02 843 has thus disclosed a scraping bar of this type, which consists essentially of a metal section of quadratic cross-section having on opposite sides welded metal plates, the two longitudinal faces and their edge of scraping are surrounded by an elastomeric material, such as synthetic rubber. Like the entire scraping bar, the scraping edge is straight and flat and can be applied by means of a scraping device not shown on the working surface of a conveyor belt, at the lower strand of it. After a relatively fast wear of the elastomeric material, the scraping edge, which is also originally a scraping edge of elastomeric material, is replaced by a metal scraping edge, which, under the action of the transported material adhering at the working surface of the conveyor belt at the middle part thereof, tends to suffer concave wear and then leads to deterioration of the working surface

of the conveyor belt.

  EP 0 004 809 discloses a multi-part scraping bar which consists of flexible round fiberglass rods which are attached at one end to a tilting shaft and carry a scraping bar at their other end. . In this, two fiberglass rods are always connected to a partial scraper batten. The sum of all the scraper slats form a continuous scraper batten, interrupted only by small gaps, which is flat both at its scraping edge and on both longitudinal sides. In the vicinity of the upper edge, hard metal gaskets are inserted as scraping edges in flat scrapers made of metal. From these hard metal linings, too, it is known from experience that, depending on the abrasive material, their scraping edges also tend to experience sawtooth wear and that damage to the conveyor belt is then

not to be excluded.

  DE 41 21 173 A1 discloses a scraping bar consisting of a metal support tube, which is provided on at least a part of its surface with a plastic scraping bar, which carries near its scraping edge. a batten of a harder material. The scraper batten is made of a polymeric material, in which a slightly folded spring steel support plate is captively embedded. This spring steel support plate carries as a scraping edge a hard metal plate. In this case also, it has been found that even when the hard metal plate is made of sintered hard metal, the scraping edge undergoes saw-tooth wear under the action of the abrasive particles of the materials transported to be scraped off. , which leads in the following to a wear plate and thus to inevitable deteriorations

  at the lower end of the conveyor belt.

  Furthermore, there is known from the brochure "HGN H. Gulich's Nachf Förrdertechnik GmbH" a scraping bar for a conveyor scraper comprising a single scraping bar or a double scraping bar mounted in parallel tandem, both sides of which

  longitudinal and also the scraping edge are flat.

  Only in the corners are rounded parts. These scraping slats are also subject to

  the same disadvantages as previously described.

  And finally - without concluding however - DE-GM 94 03 860 revealed a scraper batten, which consists of a metal carrier tube, which has on at least a portion of its surface a plastic scraper batten comprising close to its scraping edge a lath of shock-resistant ceramic material. This scraping batten of shock-resistant ceramic material is bonded to the carrier tube, either directly by a U-shaped metal support rail, or via an additional metal bracket. At least along the longitudinal side located on the side of the transported material to be scraped, the scraper batten has a concave scraping chute in order to obtain a favorable deflection of the scraped transported material. This scraping slat has proved itself in practice with respect to the state of the art known hitherto and also offers

  greatly improved scraping performance.

  All the scraping laths described above still have in common the disadvantage that their scraping edge is subjected to friction that varies greatly over the width of the lower-strand conveyor belt, which in turn depends on the abrasive materials transported and also the specific weight of the materials transported. The higher the specific gravity of the transported materials, the more the conveyor belt tends to take the shape of a trough on the upper strand, in its unsupported central part, which continues with inverted orientation at the lower strand, after the passage of a return drum or a backup roll. It is only near the return drum and

  of the support roller that this bowl shape is flattened.

  This has the consequence that a flat design scraping lath applied in the area following the return drum provides a better scraping work on the edges of the conveyor belt than in the middle part thereof. A strong support force of the lath of

  scraping, eg under the action of a spring,

  even at higher friction and therefore to

  low operating times of the scraper batten.

  From this state of the art, the object of the invention is to improve a scraping bar of the type mentioned in the preamble in that, together with higher scraping performances, it also guarantees a longer operating time. high of the

scraping batten.

  According to the invention, this object is achieved in connection with the concept cited in the preamble in that the scraper batten adapts to the concave section surface contour of the work surface at the lower strand by a convex contour of its scraping edge. Thanks to this structure, we obtain for the first time a scraper batten that takes into account the actual geometrical situation of the conveyor belt at the lower strand and thus ensures, over practically the whole width of a conveyor belt, a regular action of its scraping edge on the work surface at the bottom strand. As a result of this, with regular wear, scraping performance is greatly improved at the middle portion of the conveyor belt and consequently overall performance as well. Since the scraping edge adapts by a convex contour to the concave contour of the work surface, the gap between the two is greatly reduced, the scraping edge is also subjected to even wear on the entire work surface. of its length. This, in turn, reduces the force with which the scraper batten must be supported on the working surface of the conveyor belt, so that the scraping performance now becomes across the width of the conveyor belt. a case primarily related to the form and manner

secondary to the force.

  As an improvement of the invention, it is possible to apply the scraping edge to the lower strand on the working surface of the conveyor belt by rotating it about a tilting axis in the direction of travel of the conveyor belt. . With regard to this advantageous characteristic, the accent is put on the expression "in the direction of advancement", because, for this direction of application, the scraping edge of the scraper batten is, under the action of the movement and friction of the conveyor belt and of the transporting material adhering to it, without increasing the support forces on the scraping edge, "sucked" on oneself and thus automatically in the interstice situated between its upper edge and the underside of the conveyor belt to be cleaned, which in turn increases the scraping performance while leaving the conveyor belt. Although an application of the scraping edge around the tilting axis is also possible in the opposite direction to

  direction of advancement, it is not so advantageous.

  Advantageously, a regulator automatically modifies the position of the scraping edge around the tilting axis as a function of its wear, by tilting of the scraping edge in the direction of travel of the conveyor belt to lower strand. For this adjustment, the regulating member is composed of a previously stretched energy accumulator acting on the scraping edge, such as a mechanical or pneumatic spring or a pneumatic or hydraulic support element. In order to avoid reducing the scraping performance due to other circumstances, a spring with a stiff characteristic should always be used as a spring, because these have a high intrinsic damping and thus largely prevent lifting. the scraping edge with respect to the work surface at the lower strand. By stiff spring means a spring for which the loading force as a function of the travel path of the spring gives a characteristic curve with a steep slope, whereas on the contrary, for a characteristic curve that falls, we speak of a soft spring. This spring stiffness must be distinguished from the resting force, with which the scraping edge is supported on the work surface of the lower-strand conveyor belt. Due to the adaptation to the shape and suction effect previously described of the scraping edge in the gap, this bearing force can, even for a stiff spring of a scraping edge conforming to the invention, however, be significantly lower than for

  the scraping slats of the current state of the art.

  The regulating member must therefore simply adjust the position of the scraping edge of the scraper batten so that the gap between it and the cleaned work surface at the lower strand does not enlarge.

  because of the inevitable wear of the scraping edge.

  The scraping edge has a curved shape or a form of ploughshare along the section of the lower strand conveyor belt. In this, the plow share of the plow edge has, both transversely to the conveyor belt at the lower end and in plan view in the direction opposite to the direction of travel of the conveyor belt, a curved shape, for which, in the plan view of a central portion of the scraping edge, two lateral zones of the lower strand are curved in the form of a ploughshare. In this, the lateral zones of the contour in the form of ploughshare can have a concave or convex curvature, possibilities among which we will give preference to the concave contour because of its deflection effect favorable to

  the flow of the transported material that has been scraped.

  In addition, transversely to the direction of travel of the lower run, the scraping edge is advantageously equipped over its entire height, on the scraping side, a concave deflection surface for the transported material which has been scraped. Such concave deflection surfaces are in principle known, for example Figures 4 and 5 of DE-GM 94 03 860, cited in the preamble.

  about the state of the art.

  The scraping lath and its scraping edge can also, which is in principle known from the state of the art previously described, but is however not known from the descriptive features of claim 1, be constructed either in one element, either in several elements. For this purpose, the scraper batten is

  advantageously attached to a carrier tube, which can itself

  even be secured by locking and / or adhesion on a tilt axis, which is provided with the regulator or adjustment device for adjusting the scraping edge to the work surface of the lower strand. The scraper batten is made of a ceramic, metallic or plastic material or a combination of these materials. The metal support tube may be manufactured using St 37 to St 52 / C45 structural steel and the scraper edge may consist of an oxidized ceramic, glass-ceramic or cermet or hard metal lath fixed to the support tube which is lined at least on both longitudinal surfaces, on the scraping side and on the opposite side, of plastics material such as polyurethane, polyamide, ABS, PEEK or a thermoplastic material resistant to impacts. These materials or combinations of materials are, in principle, also known from DE-GM 94 03 860. For the application of the scraping edge on the work surface at the bottom run, preference will always be given to a damping regulator.

  intrinsic high of the entire oscillation system.

  Several embodiments of the invention are shown in the figures. These show: Figure 1 a partial perspective view of a lower strand near a return drum, with a scraper batten according to the invention, Figure 2 a sectional view along the line II-II of Figure 1, Figure 3 a perspective plan view on the scraper batten of Figure 1 in one embodiment in one element, Figure 4 a perspective plan view of a second form of producing a scraper batten, which is assembled from several scraping segments, FIG. 5 the vertical plane view on the scraper batten of FIG. 3, FIG. 5a the vertical plane view corresponding to FIG. on a scraper lath with a ploughshare contour, the lateral zones of which have a concave curvature, FIG. 5b the vertical plane view corresponding to FIG. 5 on a scraper lath with a ploughshare contour, whose lateral zones have a convex curvature e, Figure 6 sectional view on an adjustable tilt axis, with a scraper batten

arranged on it.

  FIG. 7 shows the view in the direction VII of FIG. 6, FIGS. 8 to 11 each of the views corresponding to FIG. 7 on a scraping bar made of different materials, namely steel (FIG. 8), made of steel with element hard metal or ceramic scribing edge (figure 9), low wear plastic (figure 10) and low wear plastic with ceramic or hard metal insert

  serving as scraping edge (Figure 11).

  According to FIGS. 1 to 3, the doctor blade 1 according to the invention, used for scraping on the lower strand 3 of transported material 2 on the upper strand 3a of a conveyor belt 4, consists of a scraping side 5 with a deflection surface 5a, an opposite face 6, a scraping edge 7 and end ends 8. This scraping slat 1 is in this case fixed by one of its ends la directly or indirectly on a carrier tube 9 of rectangular or square section. The scraping edge 7 is disposed at the other end 1b. According to the invention, the scraping edge 7 of the scraper batten 1 has a convex contour 7a adapted to the concave section of the surface contour 10 (see FIG. 2).

  from work surface 11 to lower run 3.

  As can be seen in particular in Figure 1, such a scraper batten 1 is disposed behind the return drum 13 to the working surface 11 at the lower run 3 of the conveyor belt 4, in the direction of advancement according to the arrow 12. In FIG. 2, a second return drum 13 is outlined in the background in broken lines. The embodiment of FIG. 4 differs from the embodiment of FIG. 3 in that, for the first, the scraping bar 1 consists of several scraper batten segments 14, which are respectively fixed to the tubes. Segment carriers 9a and by plugging on a tilting axis 15 (see Fig. 6) together with their corresponding rectangular-shaped outer contour form a common scraping bar 1 forming a whole. This embodiment has the advantage that, in case of damage to the scraping edge of individual segments 14, these can be replaced by corresponding segments without having to replace the entire scraper batten 1. In addition of its convex contour 7a, the scraping edge 7 is also curved in its plan view in the opposite direction of the direction of advancement (arrow 12) of

the conveyor belt 4.

  Figures 5, 5a and 5b show various embodiments of the curves of the scoring edge 7. In Figure 5, the scraping edge 7 has a curved shape

  plane in its view in a vertical plane.

  In FIG. 5a, the scraping edge 7 has in its plan view also a curvature in the opposite direction of the direction of travel of the conveyor belt 4 along the arrow 12, for which two lateral zones 7c, 7d have a concave curvature. inwards from

a median convex part 7b.

  In the embodiment of FIG. 5b, both the medial portion 7b and the two adjacent lateral zones 7e, 7f have an outwardly convex curvature. In this, although the embodiments of Figures 5a and 5b are easier to perform, the embodiment of the scraper edge 7 of Figure 5a has a more flow

  favorable for the deflection of the transported material.

  According to FIGS. 6 and 7, the carrier tube 9 of a scraper batten 1 in a single element or the segments of carrying tubes 9a of several scraper batten segments 14 are threaded onto the tilting axis 15 and mechanically locked onto this one. The tilting axis 15 can swing at each of its two ends 15a, 15b in bearings 16, 17 and can be locked therein by means of screws 18. Due to unavoidable wear, it is also possible to by means of these screws 18, adjust the scraping edge 7 of the scraping bar 1 on the working surface 11 of the conveyor belt 4. The bearings 16, 17 are provided with support arms 19, 20 , which can be adjustable in length and also tilt during scraping work around a second tilt axis not shown. In this, one must mainly make the difference depending on the type of applied spring. This second tilting axis can, on the one hand, be under the direct action of springs, most often of rubber springs, and by means of these, press the support arms 19, 20 as well as the lath of scraping 1 fixed on the tilting axis 15

  against the work surface 11 at the lower end 3.

  However, it is also possible to have the support arms 19, 20 act on an energy accumulator, e.g. ex. a spring on each, and to press by them the axis of tilting 15 with the scraping lath 1 and its scraper edge 7 against the working surface 11 at the lower strand 3. For this purpose, there exists, in depending on the type and shape of the springs, huge differences in the intrinsic damping that results for the entire oscillating system, which are not part of the scraper batten 1 according to the invention. Indeed, unlike the state of the art, in the case of the scraper batten according to the invention, a relatively weak force is sufficient to apply and adjust the scraping edge 7 on the working surface 11 to the strand 3, which should however be accompanied by

  high intrinsic damping.

  When applying the scraper edge 7 around the tilting axis 15 in the direction of travel of the conveyor belt 4 along the arrow 12 on the working surface 11 thereof to the lower strand 3, the scraping edge 7, and thus the entire scraping lath 1, is driven by the movement of the conveyor belt 4 and abrasive materials to be transported lying on it in the gap 21 visible at As a result, the width of this gap 21 is always automatically reduced to a minimum under the action

  a regulator in the form of an energy accumulator.

  For the automatic application of the scraping edge 7 in the direction of the working surface 11 thereof to the lower strand 3, it is sufficient for a regulator having the shape of a mechanical or pneumatic spring previously tensioned or a pneumatic or hydraulic support element or acting under the action of a weight. In this, it is obvious that the tilting axis 15 and this regulator must be designed so as to prevent the convex contour 7a (see Figure 2) of the scraping edge 7 from jumping beyond the gap 21 and doing this in a position

  necessarily enlarging the gap 21.

  In principle, an arrangement of the scraping edge 7 in the opposite direction to the direction of travel along the arrow 12 of the lower strand 3 is also possible, but it is not so favorable, because then "the effect automatic suction "of the scraping edge 7 in the gap 21 located between it and the work surface 11 of the strand

lower 3 disappears.

  When selecting the materials of both scraper batten 1 and its scraping edge 7, different embodiments are possible depending on the abrasive nature and the hardness of the materials transported to scrape, four of which are shown in FIGS. to 11: In the embodiment of Figure 8, the base body of the scraper batten 1 and its scraping edge 7 are made of steels of different qualities and hardness. In the embodiment of FIG. 9, the base body of the scraper batten 1 is manufactured for example in a tool steel, its scraping edge 7 being constituted by a hard metal insert or a ceramic. In the embodiment of Figure 10, the scraper lath 1 and scraping edge 7 are manufactured in one piece in a low wear plastic material. This embodiment, however, is primarily suitable for scraping material transported low abrasiveness. In the embodiment of FIG. 11, the basic body of the scraper batten 1 is made of a low-wear plastic material, the scraper edge 7 being constituted by a hard metal insert

or ceramic.

Claims (13)

claims   Scraper slat for scraping material conveyed from the lower run of a conveyor belt by means of a scraper edge applicable to its working surface, characterized in that the scraping bar (1) is adapted to surface contour (10) of concave section of the working surface (11) at the lower strand (3) by a   convex contour (7a) of its scraping edge (7).   2. scraping lath according to claim 1, characterized in that the scraping edge (7) can be applied to the lower strand (3) by tilting about a tilting axis (15) in the direction of advancement. (arrow 12) of the conveyor belt (4) on the surface of work (11) thereof.   3. Scraping lath according to the claims   1 and 2, characterized in that, depending on its wear, the scraping edge (7) can be adjusted automatically to the lower run (3) under the action of a regulator, around the tilting axis ( 15), by tilting the tilting axis (15) of the scraping bar (1) in the advancing direction (arrow 12) of the web conveyor (4).   4. scraping lath according to claim 3, characterized in that the regulator consists of a previously tensioned energy accumulator acting on the scraping edge (7), such as a mechanical or pneumatic spring or an element d pneumatic or hydraulic support. 5. Scraping lath according to one or more   Claims 1 to 4, characterized in that the ridge   scraping device (7) has a curved shape (7a) along the section of the conveyor belt (4) at the lower end (3). 6. Scraping lath according to one or more   Claims 1 to 4, characterized in that the ridge   scraper (7) has a plow-shaped contour (7b-7f) along the section of the web   conveyor (4) at the lower end (3).   7. scraping lath according to claim 6, characterized in that the ploughshare contour (7b-7f) of the scraper edge (7) has, both transversely to the conveyor belt (4) at lower strand (3) than in its plan view in the direction opposite to the direction of travel (arrow 12) of the conveyor belt (4), a curved shape, for which, in the plan view, two lateral zones (7c , 7f) are curved in the shape of a ploughshare from a median area (7b) of the scraping edge (7), in the opposite direction   in the direction of advancement (arrow 12) of the lower strand (3).   8. scraping lath according to claim 7, characterized in that the lateral areas (7c-7f) of the ploughshare contour (7b-7f) have a   curvature either concave or convex.   9. Scraping lath according to one or more   Claims 1 to 8, characterized in that,   transversely to the direction of advancement (arrow 12) of the lower strand (3), it (1) has on the side o is scraping, over its entire height, a concave deflection surface (5a) for the material transported (2) scraped.   10. Scraping lath according to one of the   Claims 1 to 9, characterized in that the lath of   scraping (1) and scraping edge (7) are formed into one   only element or in several elements.   11. Scraping lath according to one or more   Claims 1 to 10, characterized in that it (1)   is secured to a carrier tube (9, 9a), which in turn can be secured by locking and / or adhesion to a tilting axis (15), which is provided with the regulator or adjustment device for adaptation of the scraping edge (7) at the work surface (11) at the strand lower (3).   12. Scraping lath according to one or more   Claims 1 to 11, characterized in that it (1)   is made of a material made of ceramic, steel   or plastic or a combination of these materials.   13. Scraping lath according to one or more   Claims 1 to 12, characterized in that the tube   metal carrier (9, 9a) is made of structural steel St 37 to St 52 / C45 and the scraper edge (7) consists of an oxide ceramic, glass-ceramic or cermet or metal batten hardened to the carrier tube (9, 9a), which is bordered at least on the two longitudinal surfaces of the scraping face (5) and the opposite face (6) of a plastic such as polyurethane, polyamide, ABS, PEEK or   a shock resistant thermoplastic.