MXPA00012761A - Chain conveyor - Google Patents

Abstract

The aim of the invention is to provide a chain conveyor (1) with a more precise measuring/metering capacity and a simple construction. To this end, at least one measuring section (S), preferably a measuring bridge (2), is located between an inlet opening and an outlet opening (8, 9) and is supported on at least one force-measuring device (12). The conveyor chain (6) is guided along the measuring bridge on guiding elements (11) which are fixed at the sides, especially rails with a cross-shaped section. Part of the measuring bridge (2) can be arranged with flexible intermediate elements (10) in such a way that it is decoupled, so that the chain forces (Fk) are compensated as the force-measuring device (12), which is set apart, is impinged upon.

Description

CHAIN CONVEYOR FIELD OF THE INVENTION This invention relates to a chain conveyor with the pre-characterizing features of claim 1.

BACKGROUND OF THE INVENTION These chain conveyors are used in particular to transport bulk materials. In past years, these chain conveyors have been used more and more in base material industries (for example, in coal mining or in cement manufacturing) to measure or determine the feed rate of bulk materials, given They provide a structure that withstands wear, with great production, due to its great power of subtraction. In addition, the manufacture and service of a chain conveyor are relatively inexpensive and can be installed without problems, so that due to its robust construction it is suitable as a hopper subtraction unit, even for coarse grain abrasive bulk materials. or sticky, as described in ZKG (Zement-Kalk-Gips [ie, Cement-Limestone-Plaster]) No. 1/1993, page 380.

A disadvantage in the usual structure of a chain conveyor is, however, that the accuracy of the measurement is relatively poor, since the volumetric filling may not be very uniform, taking into account the different densities and also because the material transported It can adhere to the chain of the conveyor that connects the drag bars, during the emptying. This may result in appreciable deviations from the accuracy of the measurement, which is particularly serious for aggregate blends. Balances combined with belt conveyors or plate conveyors, are already known, for example, in accordance with DE 19536871 or with DE 4230368, where the conveyor belt or the plate strip moves on a bridge-type scale, fixed in a position. However, these conveyors have disadvantages in relation to their wear characteristics or to the required energy demand, since, on the one hand, the conveyor belts, of rubber materials, suffer from great wear, even when reinforced, and, on the other hand, the plate bands have a lot of friction, due to the relative movement between the individual articulated members, especially when they are very loaded. Accordingly, the invention is based on the object of improving the measuring accuracy of the chain conveyors, with a simple construction. This object is satisfied by a chain conveyor in accordance with the features of claim 1. The support of at least one partial region of a measuring segment, especially of a measuring bridge, on at least one force measuring device, gives As a result, precise gravimetric control over the amount of material transported by the chain conveyor. In this way, irregularities such as the inevitable differences in filling levels, in the volumetric measurement, are reliably avoided and the material adhering to the conveyor chains and the like can be detected, while the amount measured at the set point it can therefore be maintained precisely, in the manner of a measuring scale with a regulated actuator. Due to the defined conduction of the conveyor chain in the region of the measuring segment, the disturbing forces, for example, of the clogging of the granular material between the drive members and the measuring bridge, can be eliminated to a large extent, in such a way that the measurement segment itself is, to a large extent, free of external forces, in the manner known from technical mechanics, as "isolated", even in the case of very high traction forces in the chains. A closed system unit results from driving the conveyor chain in the region of the measuring segment, where the conveyor chain is held securely. This can be assisted in a simple way by a slightly peak form of the measuring bridge, so as to result in a predetermined preload on the measuring segment disposed in the tensioned section, reliably avoiding the elevation of the conveyor chain even when a loose or variable tension is present in the chain. In this way, the problems of uneven feeding, such as may occur in the arrangement that is in the loose section, without pulling force, are likewise reliably avoided. A particularly simple design of the conveyor chain, proposed, results in the measuring bridge of the chain conveyor being pivotally arranged on a defined axis, preferably arranged centrally in the circulation plane of the chain, and the Measurement of weight or force, is separated from this axis. This arrangement is particularly suitable for the retroactive adjustment of the existing chain conveyors, in the tensioned section, with the conveyor chain driving over the measuring segment, since the retroactive adjustment of the chain conveyor, with the measuring device of gravimetric force, it is possible by simply fixing bolts or other supports that form the shaft, for example also of the conveyor devices of drag links. The same applies to the mobile assembly of only a part of the measuring bridge, which is decoupled by means of flexible intermediate elements. By interposing flexible intermediate elements, especially rubber and steel composite bars or by weakening the material in the manner of a film hinge and support on the measuring device, a simple retroactive adjustment of existing chain conveyors can be achieved. A particularly advantageous design has two measuring bridges, wherein a second tare measuring bridge is arranged before the hopper feeding inlet or opening and after the outlet opening, such that the actual discharge amount in the The outlet opening can be determined, and in this way a tare measurement can be made. The arrangement of the two bridge parts, which are connected to each other by a link and act only on a single force measuring device, in the manner of a shaft, is possible to detect the weight of the chain and the member of drag in a simple way. Advantageous, additional arrangements will be apparent from the following description of the modalities shown in the drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a chain conveyor in side view; Figure 2 shows a portion of the chain conveyor according to Figure 1, in an enlarged side view, in the region of the measurement segment; Figure 3 is a cross-sectional view of the side region of the chain conveyor in the region of the measurement segment, along the section line III in Figure 2; and Figure 4 shows a portion of the region of the measurement segment, of the chain conveyor in a plan view.

DESCRIPTION OF THE INVENTION A chain conveyor 1 is shown in figures 1 and 2 in side view and an enlarged view, associated, in the measurement region, respectively, located in a housing or hopper 3 and comprising a measurement segment S extending in a straight line, which is located in the upper section 5 and which is also called the lower measuring bridge 2. A chain 6 of the conveyor circulates along the measuring bridge 2 in the housing / hopper 3 and has drag bars 7 at regular intervals. Bulk material, which enters the accommodation 3 > . from an opening 8 (here, from a hopper or silo), it is transported by means of the drag bars 7 along the measuring bridge in the upper section 5 and then along the lower section 4 to an opening of exit 9, in the opposite direction to the movement of the hands of the clock, as shown in the present by arrows. Between the inlet / fill opening 8 and the outlet opening 9 the measuring bridge, of the plate type, 2, is mounted by means of flexible intermediate elements 10 so that it can move or yield slightly, or uncouple in the vertical direction, being supported on at least one force measuring device 12 disposed below the measuring bridge 2, especially a device for measuring force, arranged approximately at a central location. Near the left end of the measuring bridge 2 an actuator 13 is provided in the shape of a gear wheel which is coupled to the chain 6 of the conveyor. After being transported along the measurement segment S or measurement bridge 2, the conveyed material (indicated by dots) falls, passes quickly in front of the actuator 13 on a wear resistant bottom plate in the region of the lower section 4 and finally it passes through the horizontal feed through the chain 6 of the conveyor and the drag members 7 formed by rods, towards the outlet opening 9, where it can fall out by gravity or blowing. It should be noted that this blowing device, not shown, can be placed in the housing 3, especially with a design of the chain conveyor that does not lose pressure or airtight, so that no disturbing moment can be exerted on the device • Force measurement 12. In addition, the cleaning of the chain elements and / or the driving members 7 can be carried out by the latter, which can be assisted by a reciprocating brush. The conduction along the curvature 15 of the housing, here on the right side, is also important, since the bulk material that has not been ejected can be fed back to a second measuring bridge 22. • 20 (in the same way with a force measuring device 12) for the weighing of the tare. Any force measuring devices, such as shear force transducers or load cells that work on inductive, capacitive or piezoelectric bases, can be used, such as the device for force measurement 12 for measurement bridges 2, 22.

A force measuring device 12 is preferred which measures practically without bending, especially a load cell for measuring force based on a strain gauge, since the bending angle of the measuring bridge 2 can be restricted to a few minutes of arc by this one, such that the movement of the conveyor 6 chain is not completely impeded. In this way, a pivotal axis 18 is formed by the flexible intermediate elements 10 (see also FIG. 2), around which the parts of the measuring bridge can flex slightly as an oscillating beam or hinge with straight bridge plates. These bridge plates of the measuring segment S are preferably designed in slightly peak or polygonally raised or "bent" form, as shown, in an exaggerated manner, for clarity, by the angle ß. In this way, the chain 6 of the conveyor is reliably constrained by "tension" so that it does not rise from the measurement segment S and a preload or force Fk of the chain, directed downwards, is obtained which acts as a result on the load cell 12 together with the gravitational force Fm of the bulk material (compare the parallelogram of forces). The force Fk of the chain acts in equal measure on the discharge end of the measurement segment S, here on the left side, and can be measured there by means of a second load cell 12 ', in such a way that the effective weight of the transported material (ie, Fm) -. through the measurement segment, it can be determined by subtracting this value Fk, from the value of the device 5 »to measure force 12 (ie, Fm + Fk). The device for measuring force 12, 12 'passes the measured value to a computer that calculates the amount of instantaneous production, by forming the product of it together with velocity values, such as those obtained, for example, at 0 from a tachometer located in the actuator 13. This actual value is preferably compared with a preset set point value, for measurement purposes, and the controlled actuator 13 is regulated in a manner known per se when there are deviations. The lateral region of the chain conveyor is shown in Figure 3, wherein the design of the guide elements 11 shown also in Figures 1 and 2 for the "positive" retention of the chain 6 of the conveyor, on the measuring segment S, can be seen in cross section 0. It is essential that the guide elements, grooved, in the form of a bar, 11, are arranged on the measuring bridge 2, in such a way that the excessive forces in the chain, which may occur, do not pass to the results of the measurement or are eliminated. The chain 6 of the conveyor is thus accurately guided on both sides in the cruciform, grooved guiding elements, while the driving rod 7 is inserted by means of a fork connecting element 27 (see FIG. 4), known per se. is, inserted in the chain elements that are on the shore. It is possible to ignore the lateral guidance function of the guiding elements 11, so that the chain 6 of the conveyor can be prevented, for example, from being lifted out of the measuring segment S, by means of a smooth bar, while the bottom side of the conveyor chain 6 can be moved on a PTFE strip on the measuring bridge 2. Rollers or wheels could also be provided to guide and support the conveyor chain 6 on the measuring segment S, as shown in the figure 3 using the lines of dashes and points. The measuring bridge 2 can also be manufactured in one piece, as long as it can be supported followed by the short inwardly sectioned and outwardly sectioned zones, in its end regions (referred to as the transport direction). on four load cells 12 'as indicated in figure 1 with the dashed lines, and where the part of the measuring bridge 2 which is towards the hopper, is movably mounted by at least one flexible intermediate element 10. In this design also, with four force measuring devices 12 the measuring bridge 2 can move down slightly below the load of the transported material, during the feeding of the bulk material and thus act on the two force measuring devices 12 in the manner of a bridge-type scale. After passing the measuring bridge 2 forming the measuring segment S, the transported material finally reaches the exit opening 9 and at that point it falls outwards and downwards, between the dragging bars 7. As indicated in the figure 1 with dashed lines, the outlet opening 9 'can also be arranged below the filling opening 8 or in the vicinity of the actuator 13. The second measurement bridge 22 that follows the outlet opening 9 can also be supported on two force measuring devices 12 or be mounted or uncoupled on intermediate elements 10. The dead weight of the chain 6 of the conveyor, with the driving members 7, can therefore be detected, such that the actual amount of the transported material which reaches the outlet opening 9 can be determined by forming a difference, comparing the two measured values of measurement bridges 2 and 22. If the particles of the material transp However, the amount of bulk material that actually leaves the chain conveyor 1 would be determined. Through this measurement of the tare an appreciable increase in the accuracy is possible. of the measurement and measurement. It should be noted that the second measuring bridge 22 can also be arranged in the lower section 4, depending on the position of the exit opening 9, in such a way that the arrow of the chain 6 of the conveyor and, thus, the load of the force measurement devices 12 is the same in each case and can thus be eliminated from the measurement results. As shown above, a bending of the measuring bridge 2 is involved only of a flexion angle (ß) of a few minutes of arc or seconds of arc, such that the movement of the chain 6 of the conveyor does not is prevented. A pivotal support with side connecting plates 11 'can also be provided as a flexible intermediate element 10 between the guiding elements 11, as indicated in Figure 2 with dashed lines. The shaft 18 thus formed to facilitate the rotational capacity of the measuring bridge 2 (see FIG. 2) lies preferably in the plane of circulation of the chain, above the measuring bridge 2. The force measuring device 12 is arranged in an off-center position, below it, in such a way that a defined lever arm is obtained, from the axis 18. Instead of the connection plates / bolts, other lower friction supports can be provided, to form the axis 18 , although the chain 6 of the conveyor, as such, can also form an articulated link in its plane of circulation, since the distance between the guide elements 11 represents approximately two or three chain members. It should be noted that the measured values of the force measurement device (s) 12 are passed to electronic evaluation components, with a computer, in a manner known per se, to calculate the instantaneous feed rate from the loading of the measuring bridge and the speed of the conveyor, and they are compared there with established set point values. By accelerating or braking the actuator 13 of the chain conveyor 1, for example by electronic speed regulation, the desired feeding or measuring quantity (feed rate or feeding power) can thus be maintained accurately, even with materials that They are relatively difficult to transport, such as slag or even mud.

Claims (20)

NOVELTY OF THE INVENTION ~ • Having described the above invention, it is considered as a novelty, and therefore, it is claimed as 5"property contained in the following: CLAIMS

1. A chain conveyor for the 0 measurement / gravimetric measurement, especially of bulk materials, with a housing / hopper, in which at least one chain of the conveyor circulates, with drag members fixed thereto, as well as an inlet opening / filling and an outlet opening in the housing / hopper, wherein at least one measuring segment is arranged between the inlet / fill opening and the outlet opening and is supported on at least one force measuring device, characterized in that along the measurement segment (S) the chain of the conveyor 0 is guided positively and / or under tension, on the measurement segment (S), especially of a measuring bridge on guide elements fixed thereto.

2. A chain conveyor according to claim 1, characterized in that the measurement bridge is pivotally mounted about an axis and the force measuring device is spaced apart from the axis.

3. A chain conveyor according to claim 2, characterized in that the shaft extends approximately centrally between two parts of the measuring bridge in the plane of circulation of the chain.

4. A chain conveyor according to claim 2 or 3, characterized in that the force measuring device is arranged at the point of the part of the measuring bridge, farthest from the axis.

5. A chain conveyor according to any of claims 2 to 4, characterized in that the force measuring device is arranged approximately centrally below the measuring bridge. A chain conveyor according to claim 1, characterized in that a part of the measurement bridge is decoupled relative to the remaining part of the measuring segment by at least one flexible intermediate element. 7. A chain conveyor according to any of claims 1 to 6, characterized in that the measuring bridge is arranged on the upper section. A chain conveyor according to any one of claims 1 to 6, characterized in that the measuring bridge is arranged on the lower section, especially for weighing the tare. 9. A chain conveyor according to any of claims 1 to 8, characterized in that the entire measuring bridge is supported on at least three force measuring devices. A chain conveyor according to any one of claims 1 to 9, characterized in that a second measuring bridge is supported on at least one additional force measuring device followed by the exit opening or a housing curve. return and the force measuring devices of the two measuring bridges are connected or coupled together to form the difference of the measured values. A chain conveyor according to any of claims 6 to 10, characterized in that the first and second measurement bridge parts are supported on a single common force measurement device. A chain conveyor according to any one of claims 1 to 11, characterized in that the lateral guide elements are of cross-sectional shape. 13. A chain conveyor according to any of claims 1 to 12, characterized in that the guide elements are formed by 5 t rollers or wheels to support the chain of the conveyor. 14. A chain conveyor according to any of claims 2 to 13, characterized in that the guide elements are pivotally connected in the vertical direction in the region of the axis 0 by means of connection plates. 15. A chain conveyor according to any of claims 1 to 14, characterized in that the force measuring device is coupled to a computer, in which, in order to determine the instantaneous production of material transported, the product is formed from the weight values of the force measuring device and the speed of the conveyor, which is detected by a speed measuring device, especially in the actuator, and 0 especially for the measurement, the computer comprises a comparator for comparing the instantaneous production of the conveyed material, with a set point value, and a controller for controlling the actuator. 1

6. A chain conveyor according to any of claims 1 to 15, characterized in that the drive members have an arrow formation between the conveyor chains, and are - * specially guided on the guide elements, a minimum distance above the measuring bridge in order to reduce 5 t wear. 1

7. A chain conveyor according to any of claims 1 to 16, characterized in that a cleaning device is provided that circulates in the feed direction, for 0 the drag bars and / or for the chains of the transporter. 1

8. A chain conveyor according to any of claims 1 to 17, characterized in that the measurement bridge is slightly bent or has a peak shape, and the force measurement device (s) is (n) arranged to detect the forces (Fk) of the chain, of the conveyor chains. 1

9. A chain conveyor, according to any of claims 1 to 18, characterized in that the measuring bridge is arranged directly adjacent to the entry opening in particular as a device for subtracting the contents of a hopper. 20. A chain conveyor, according to any of claims 16 to 19, characterized in that the central parts of the driving members are dragged in the feeding direction and center the conveyed material towards the center, especially together with a deviating region of return.