Gravimetric measurement unit for flowable bulk materials

Abstract

The gravimetric weighing unit for bulk materials according to the invention comprises a weighing device with a container for the bulk material to be weighed and a base unit with a horizontally arranged conveyor for the bulk material. The container and the base unit can be separated from each other for maintenance. The weighing unit also comprises a frame with at least one weighing scale, on which the weighing device is supported during operation via a mounting, the weighing unit being designed for a process of gravitational weighing. The mounting is connected to the container of the weighing device and supports the weighing device via the container. The container comprises a rail protruding away from the container, the base unit has a support structure running on the rail, the support structure being movable back and forth between an operating position and a maintenance position. In this way, maintenance of the base unit is facilitated without excessive stress on the mounting of the weighing unit due to forces acting on the base unit.

Description

[Technical Field]

[0001] The present invention relates to a gravity measuring weighing unit according to the preamble of claim 1 .

[0002] Gravimetric weighing devices, also known as differential weigh scales, are widely used in many sectors of industry for any kind of flowable or bulk material, i.e., bulk material that can at all events be transported by the gravimetric weighing device. The bulk material is dispensed into a container, from the container to a base unit located below it, and from the weighing device by a conveyor located within the base unit. Because the weighing device is installed above the scale, the weight recorded by the scale is the total weight, i.e., the known constant weight (tare) of the components of the weighing device plus the variable weight (net weight) of the bulk material currently present in the container and in the base unit.

[0003] In this way, the weighing scale continuously records the weight loss of the entire weighing device during operation, and therefore the weight loss of the bulk material present in the weighing device, since the weight of the weighing device is constant.The control device of the weighing device can determine the actual mass flow rate of the dispensed bulk material from the weight loss, compare it with a predetermined target mass flow rate, and control the dispensing conveyor accordingly to minimize the difference between the actual mass flow rate and the target mass flow rate.

[0004] In some cases, such as in the pharmaceutical sector or when adding color pigments in industrial production, very precise control of the output mass flow rate may be required. Furthermore, the target mass flow rate may be small (e.g., a few kilograms per hour) in the case of the aforementioned color pigment or pharmaceutical production, or large (e.g., more than one tonne per hour) in, for example, plastics production or mining, and precise dosing may also be required for such deliverable volumes.

[0005] All types of precision weigh scales with a resolution of 1:100,000 or better are commonly used, such as Coperion K-Tron weigh scales with vibrating wire sensors known as the SFT-III, SFT-II-M, and SFT-II-L.

[0006] These scales have a resolution of up to 1:4,000,000, so accurate dosing can be carried out without problems, even with vessel capacities of several hundred kilograms and conveying rates of several tons per hour. For example, with a resolution of 1:1,000,000, a dispensed mass flow of 1 kg / s (3.6 t / h) can be recorded to an accuracy of 1 / 10 g and used for weighing at a vessel capacity of 100 kg. For smaller mass flow rates, the mass flow can be measured to an accuracy of 1 / 100 g or 1 / 1,000 g.

[0007] In order to take advantage of the accuracy of the weighing scales, non-vertical conveyors, i.e. horizontal or inclined conveyors, are preferred because in a horizontal conveyor, gravity does not act in the direction of transport and therefore does not interfere, allowing for somewhat better control of the hydrodynamic behavior of the bulk material. Longer screw conveyors are well suited as horizontal conveyors because the actual flow rate can be changed very easily and without delay via their rotation speed and because they allow for a suitable connection between the mass flow from the hopper and a collection container located outside the metering unit without any disadvantage to the actual mass flow rate itself.

[0008] The K4G-L Group K-Tron product information, K4G Continuous Gravimetric Blender brochure, shows the equipment of a gravity measuring weighing unit with various hopper volumes and precision weigh scales, which allows for high-precision feeding at various flow rates as required.

[0009] Depending on the bulk material being conveyed, regular maintenance, in particular cleaning of the base unit of the metering device, i.e. the conveyor, such as a screw conveyor, is essential.

[0010] WO 2006 / 010475 shows a metering device for bulk materials and a metering unit with a frame for the metering device, which has a vertical short screw. The metering device is assembled on a plate-like extension of the frame, and the frame or extension holds, via vertical guide rods arranged on it, a bulk material container on the one hand and a base unit for the metering device on the other. The base unit can be lowered and rotated along the guide rods, allowing maintenance work to be performed without completely separating and removing it from the metering device.

[0011] Furthermore, although it is generally disclosed that the illustrated apparatus for gravimetric weighing can also be installed on a weighing scale, it remains unclear how this can be done. Furthermore, the illustrated apparatus cannot be used on longer screw conveyors, or in particular on horizontal screw conveyors.

[0012] The object of the present invention is to further develop a weighing unit with a precision scale and a non-vertically, preferably horizontally, positioned conveyor in such a way that the base unit is easily accessible for maintenance.

[0013] This object is solved by the features of claim 1.

[0014] The fact that the weighing device is suspended from the frame via the container, with the rails similarly located on the container itself, means that there is no need for a complex double suspension system that supports the container on the one hand and the base unit on the other, but which rests as a whole on the scale to record the weight of both the container and the weighing device.

[0015] Beyond the set objectives, the limiting device according to the features of claim 2 makes it possible to use a simplified, cost-effective suspension designed only for stresses in the direction of gravity forces, without for stresses caused by forces acting in all directions during maintenance.

[0016] The present invention will now be described in more detail with reference to the drawings.

[0017] In the figure, 1(a) and 1(b) show a schematic embodiment of the present invention. 2(a) and 1(b) show yet another schematic embodiment of the present invention. Figures 3(a) to 3(c) show diagrams of further embodiments of the present invention. Figure 3(d) shows a three-dimensional partial view of the embodiment according to Figures 3(a) to 3(c). 4 and 5 show three-dimensional details of two embodiments of the parallel arms of the parallel guide for the containers of the metering unit.

[0018] FIG. 1(a) shows a metering unit (1) according to the present invention, which includes a metering device (2) with a funnel-shaped container (3) for bulk material and a base unit (4). The base unit (4) also includes a drive (5) and a horizontally adjusted conveyor with a screw conveyor (6) driven thereby, which terminates in a collector (7) shown in dashed lines. The drive (5) further includes a motor (8) and a gearbox (9) to which the conveyor is connected. The control device for the rotation speed of the motor (8) and thus the screw conveyor (6) is known to those skilled in the art and has been omitted to simplify the illustration. In the illustrated embodiment, a transfer hopper (10) is also provided in the conveyor container (11), and the screw conveyor (6) extending into the conveyor container 11 is shown in dashed lines. It should be noted that while screw conveyors (6) are widely used for horizontal conveyance, other conveyor designs not suitable for vertical conveyance are also known to those skilled in the art.

[0019] During operation, bulk material is filled into the container (3), from which it falls via a transfer hopper (10) into the conveyor receiver (11), where it is transported to the left by a screw conveyor (6) operating in a conveying pipe (6') into the collector (7).

[0020] The suspension (12) supports the weighing device (2) on its right side via a cantilever (13) on a weighing scale (14), which in turn rests on a suitably designed support (15) on a frame (16). The suspension (12) supports the weighing device (2) on its left side via a parallel guide (17) which, in the illustrated embodiment, has an upper parallel arm (18) and a lower parallel arm (19), the parallel arms (18, 19) being equipped with end joints (20, 20') and (21, 21') and connecting the frame (16) and the container (3) in such a way that the container (3) is suspended so as to be vertically movable relative to the frame (16).

[0021] The result is a gravity measuring weighing unit comprising a frame (16), a weighing device (2) and a suspension (12), said suspension (12 preferably having parallel guides (17) on which the container 3 is suspended, said parallel guides (17) being connected on the one hand to the frame (16) and on the other hand to the container (3) of the weighing device (2), the container (3) being movable vertically relative to the frame (16).

[0022] The controller (omitted for simplicity, as mentioned above) can continuously determine the weight of the weighing device (2) in a gravity measurement calculation based on the weighing signal of the weighing scale (14) and the illustrated device configuration, and can therefore control the motor (8) for accurate weighing by the screw conveyor (6). The vertical movement of the parallel guides (17) frees the container (3) and thus the weighing device (2) from the vertical influence of the frame, allowing the weighing scale (14) to determine the actual weight of the weighing device (2). It should be noted that depending on the weighing scale (14) used, the required vertical displacement by the parallel guides (17) can also be very small, especially if the weighing scale (14) is designed as a vibrating wire weighing scale. However, to ensure correct weighing, i.e., precise weighing by the weighing unit (1), the weighing device (2) must be separated from the frame (16) by a vertical distance corresponding to the scale used, with respect to vertical forces.

[0023] The figure also shows a rail (25) which is fixed to the container (3) at its inner end area (26) and which is free-floating at its other outer end area (27), but which is preferably resiliently deflectable downwards.

[0024] A support structure (28) comprising running elements (29) and a mast (30) runs along the rail (25), and a base unit (4) is suspended from the support structure (28) and can move back and forth along the length of the rail (25). In Figure 1(a) it can be moved to the left, towards the vessel (3) to an operational position (i.e., operably connected to the vessel (3) for gravimetric weighing), and to the right, away from the vessel (3) to a maintenance position (i.e., detached from the vessel (3) and accessible for maintenance work).

[0025] Below the outer end area 27 of the rail 25 there is a second support 31 arranged on the frame, on which a support bearing 32 for the outer end area 27 of the rail 25 is arranged. Furthermore, lateral limit stops 33, 33' of a limiting device 34 are provided on the second support 31 (see Figure 1(b)). In the figure, limit stop 33' is hidden by limit stop 33.

[0026] Figure 1(b) shows the embodiment of Figure 1(a), with the base unit (4) moved to the maintenance position. The weight of the base unit now rests on the outer end area (27) of the rail (25), which is preferably designed to be vertically resilient in response to this weight, and thus descends until it strikes and rests on the support (32). The outer end area (27) simultaneously retracts between the lateral limit stops (33, 33') and is horizontally fixed between them with a predetermined tolerance, which is predetermined by the suspension (12). When the base unit (4) is operated in the maintenance position, the rail (25) acts as a lever, transmitting all forces resulting from the operation to the container (3) and from the container (3) to the suspension (12), which must absorb these forces. In this way, the horizontally acting force component rotates the container (3) around the vertical axis (35). The tolerances of the limiting device (34) allow for tolerable twisting and also prevent unacceptable twisting.

[0027] Complex reinforcement of the suspension (12) with respect to the horizontally acting force components that rotate the container (3) about its axis (35) is no longer necessary, and on the contrary, a simplified and cost-effective suspension (12) is possible.

[0028] As a result, the outer end area (27) is supported by the frame, i.e., the weight of the base unit (4) is borne by the frame, and horizontally acting forces resulting from maintenance are also absorbed by the frame (16) via the limit stops (33, 33'). Thus, rotation of the container (3) around the vertical axis (35) is prevented or limited to a predetermined value depending on the design of the limiting device (34). As a result, the suspension (12) can be designed in a simplified manner, solely for the weight force of the weighing unit (2), and efforts to accommodate horizontally acting forces or moments resulting from maintenance of the base unit (4) are omitted.

[0029] This means that in the maintenance position the base unit (4) is attached to the frame (16), but in the operating position it is completely detached from the frame with the rails (27) floating freely (Figure 1(a)), so that the frame (16) cannot exert a force on the base unit (4) that would cause the scale (14) to misweigh the base unit (4).

[0030] Preferably, the rails 25 are designed to be vertically resilient, and support bearings 32 are provided on the frame 16, so that when the base unit 4 is in the maintenance position, the rails 25 rest on the support bearings 32, and when the base unit 4 is in the operating position, the rails 25 rest on the support bearings 32 when the resilient deflection is downward. Furthermore, a limiting device 34 is preferably provided on the frame 16, which limits the rotation of the container 3 relative to the frame 16 about a vertical axis 35. The limiting device 34 also preferably has stops 33, 33' connected to the frame 16, which interact with the rails 25.

[0031] However, it should be noted at this point that the parallel guides (17) and / or the support of the weighing scale can also be designed to be sufficiently rigid to absorb all forces acting on the rail during maintenance. In this case, the expense of a vertically spring-elastic design of the rail and limiting devices is not necessary. Furthermore, the advantage of the simple design of the suspension itself, which only engages with the container (3), remains, and the rail placed on the container (3) no longer needs to be supported by the frame, thus ensuring that the weighing unit is completely decoupled from the frame during gravity measurement operations, at least in the direction of the gravitational forces.

[0032] 2(a) shows a further embodiment of a weighing unit (40) with an improved rail (41) designed in several parts. The container-side part (42) of the rail (41) is fixed at one end (43) to the container and preferably extends horizontally away from the container (3). Similarly, the frame-side part (44) of the rail 41, which is preferably horizontally adjusted, is fixed to the frame (16). Both parts (42, 44) of the rail (41) are aligned with each other and have an intermediate space (45) between them, which separates the container (3) from the frame but is designed to allow the running element (29) of the support structure (28) to pass through the space.

[0033] In the operating position of the base unit 4 shown in FIG. 2(a), the base unit 4 rests on the inner part 42 of the rail 41 and is connected to the container 3, and the weighing scale 14 detects the full weight of the weighing unit 2. The inner part 42 is separated from the frame 16 by a space 45, so that the frame does not exert any force that could mislead the weighing. During operation of the weighing unit, the container is free to move in the direction of the double arrow 48 due to changes in the weight of the weighing unit 2. This movement, caused by the weighing scale 14 during the weighing process, is permitted by the suspension 12 or parallel guide 17. This is similar to the case in the embodiment according to FIG. 1(a), when the outer end area 27 of the rail 25 is free to float.

[0034] When in the maintenance position, the support structure (28) with the running elements (29) rests on outer parts (44) of the rails (41) which are rigidly connected to the frame and are therefore supported by the frame (16), and the forces acting on the base unit due to operation are not transmitted to the container (3) due to the space (45), so that the suspension is protected from corresponding stresses and can be designed in a simplified manner only for the gravitational forces of the gravity measurement operation.

[0035] Preferably, the rail (41) is designed in several parts, with a container-side part (42) connected to the container (3) and a frame-side part (44) connected to the frame (16), the parts (42, 44) of the rail (41) being aligned with each other and movable relative to each other, and the support structure (28) being movable through an intermediate space (45) between the adjusted ends.

[0036] Figure 2(b) shows a top view of a rail (41) in a further embodiment modified compared to Figure 2(a). Part of the container (3) to which the inner part (42) of the rail (41) is fixed and part of the frame (16) to which the outer part (44) of the rail (41) is fixed are visible. The parts (42, 44) are aligned so that an intermediate space (45) is formed between the oppositely shaped ends (46, 47) of the parts (42, 44). In the illustrated embodiment, part (42) has a rectangular cutout (46) into which the rectangular projection (47) of part (44) projects. This design allows the container-side part (42) to move freely relative to the frame-side part (44) in the direction of the double arrow (48) (Figure 2(a)) via the intermediate space (45) (i.e., the container (3) is separated from the frame), but the intermediate space (45) is designed so that the support structure (28) or the running element (29) can easily cross it.

[0037] Furthermore, this embodiment has the advantage that the rotation of the container (3) on the suspension (12) is limited, for example, already when the base unit (4) is released from its operating position, since then the interacting notches (46) and the projections (47) abut laterally against each other. The projections (47) or the notches (46) therefore correspond to the lateral stops of the limiting device (49) and act similarly to the stops (33, 33') according to Figures 1(a) and (b).

[0038] It should be noted that a person skilled in the art can form intermediate spaces (45) or protrusion / notch combinations as desired in a particular case to achieve the effects of the present invention according to the specific design of the suspension (12) and the support structure (28).

[0039] The limiting device (32) further preferably has laterally interacting stops at the aligned ends of the rails (41), preferably alternating interlocking projections (47) and notches (46).

[0040] Figures 3(a) to 3(c) show a side view (Figure 3(a)), a bottom view (Figure 3(b)), and a three-dimensional partial view (Figure 3(c)) of the weighing unit (50) from an oblique downward angle looking towards the rail 51 and limiting device (52) of the weighing unit (50). In each figure, a coordinate system (53) indicates the height h, length l, and width b of the weighing unit (50). In Figure 3(d), the rail (75) with the limiting device (52) of the weighing unit (50) is shown in more detail in an exploded view.

[0041] FIG. 3(a) shows a side view of the metering unit (50), which has a cylindrically designed container (54) for the bulk material of the metering device (55), (55) The weighing unit (50) has a connection (56) for the bulk material to be replenished, a transfer funnel (57), and a conveyor container (58) (in which a horizontal screw conveyor, not visible from the outside, operates). The screw conveyor runs through a further conveying pipe (59) which opens to the left from the conveyor container (58) into a vertical transfer pipe (60) from which the metered bulk material is discharged downwards. A motor (61) drives the screw conveyor, and a gearbox (62) (see Figure 3(b)) between the motor and the screw conveyor (corresponding to gearbox (9) in Figure 1(a)) is covered by a vertical support (63) outside the frame (64) of the weighing unit (50). In the illustrated embodiment, the motor (61), gearbox (62), transfer funnel (57), conveyor container (58), conveying tube (59) and transfer tube (60) form a base unit (73) of the metering device (55).

[0042] The outer vertical support (63) conceals a second outer vertical support (63') located behind it, and the inner vertical support (65) of the frame (64) also conceals an inner vertical support (65') located behind it. The vertical carriers (63, 63', 65, 65') stand on a base plate (66) and in particular carry the outer and upper lateral carriers (67), which are hidden by the outer vertical carrier (63) in Figure 3(a) but are shown in dashed lines for a better overview. The lateral carriers (67) are designed in an inverted U-shape in cross section and are visible from below in Figure 3(b).

[0043] The lateral carrier (67) serves as a support for a weighing scale (68), on which the container (54) is supported by a vertical carrier element (69) with a cantilever (69') (corresponding to the cantilever (13) in Figure 1(a)). The carrier element (69) is part of a suspension (80).

[0044] On the opposite side, inside the weighing unit (50), one can see the vertical frame part (70) of the suspension (80), on which are arranged upper parallel arms (71) and lower parallel arms (72), which support the container (54) so ​​that it can be displaced vertically as far as required for the movement of the weighing scale (68) during the weighing process. A control device (74) is here arranged on the weighing unit (50) itself and controls the weighing process in a manner essentially conventional and known to those skilled in the art.

[0045] Figure 3(b) shows the weighing unit (50) from below, with the weighing scale (68) hidden in the lateral carrier (67). The trapezoidal outline of the frame (64) can be seen, with a narrow side at the location of the transfer tube (60) and a wider side on the outside where the controller is also located. Although not shown, this arrangement allows a group of six weighing units (50) to be arranged as a hexagon around a common collector.

[0046] Also shown is a second part (81) of a further embodiment of the rail (75) (Figures 3(c) and 3(d)) of the limiting device (52) for limiting the rotation of the container (54) around the vertical axis (35) and a second side part (98) of a correspondingly designed limiting carrier (95) (Figures 3(c) and 3(d)).

[0047] Figure 3(c) shows a section of the weighing unit (50) in three dimensions from diagonally below, with rails 75 projecting away from the container (54) and covered by a protective casing (76) arranged on the lateral carrier (67). As mentioned above, the lateral carrier (67) is designed with an inverted U-shaped cross section and is arranged on the vertical carrier (63, 63') with its closed side facing upwards, carrying the weighing scale (68), which in turn carries the vertical carrier element (69) and thus the container (54) via the support arm (69') (see Figure 3(a)).

[0048] The downwardly extending carrier portion (77) of the carrier element (69) terminates in a horizontally adjusted connecting plate (78) to which the mounting head (79) of the rail (75) is fixed, thereby fixing the rail (75) to the carrier element (69) (and thus to the container (54)). The rail (75) is shown in detail in Figure 3(d).

[0049] In the illustrated embodiment, the rail (75) has a first portion (82) extending away from the container (54) and a second portion (81) adjacent to the first and bending back towards the first portion. Furthermore, in the illustrated embodiment, the rail (75) is designed as a double rail, with two individual rails (85) and (86) extending laterally adjacent to each other and spaced a short distance from each other to form a gap through which protrudes a mast 87 from which the base unit (73) (see also FIG. 3(a)) is suspended.

[0050] In addition to the support structure (83) of the base unit (73), the mast (87) has running elements designed as a lower sliding disc (88) and an upper sliding disc (89). When the clamping or sliding discs (88, 89) are pressed against each other, the discs secure the base unit (73) to the rails (75), which are in the working position in Figure 3(c). When the sliding discs (88, 89) are released from each other, the base unit (73) can be moved along the gap between the individual rails (85, 86) via the mast (87).

[0051] The base unit 73 is moved to the maintenance position by releasing the clamping ring 90, which connects the transfer funnel 57 to the container 54 via the fastening screw 91, and is suspended on the rail 75, supported only by the support structure 83. The base unit 73 with the disengaged sliding discs 88, 89 can then be pulled away from the container 54 until the screw conveyor is withdrawn from the transfer tube 60, which is generally when the support structure 83 or mast 87 is in the outer area of ​​the first section 82 of the rail 75. The base unit 73 can then be rotated counterclockwise around the axis of the mast 87 and simultaneously pushed along the second section 81 until the screw conveyor is parallel to and outside the transverse carriers 67. One advantage of this design of rails (75) is that the base unit (73) does not have to be pulled away from the container (54) in a straight line over the entire length of the screw conveyor, which saves space and allows for tighter space requirements for a particular line from a maintenance standpoint.

[0052] For this purpose, the support structure (83) is preferably designed so that the base unit (73) can rotate relative to the rails (75). In the illustrated embodiment, this is easily possible, since the mast (87) can rotate at any time in the gap between the individual rails (85, 86) in accordance with the layers of the screw conveyor when the sliding discs (88, 89) are loosened relative to one another. Even more preferably, the support structure (83) comprises a mast (87) protruding between the individual rails (85, 86), and even more preferably comprises discs (89) on the individual rails (85, 86), which discs (89) are designed as sliding discs.

[0053] FIG. 3(d) shows in exploded view rail 75 and limiting carrier 95 which includes rail 75 when assembled as shown in FIG. 3(c).

[0054] In addition to the connecting plate (78) that secures the rail (75) to the downwardly extending carrier portion (77) and thus to the container (54) (see Figure 3(c)), the rail 75 also comprises a first limiting cam (100) that projects outwardly at the end of the first portion (82) and a second limiting cam (101) that projects outwardly from the second portion (81) at the end of the second portion in the illustrated embodiment.

[0055] Each of the limiting cams (100, 101) has a rectangular outer shape, a lower surface (102, 103), an opposite upper surface that is hidden in the figure by the lower surface (102, 103), outer surfaces (104, 105), left side surfaces (106, 107) and right side surfaces (108, 109), and the left side surfaces (106, 107) and right side surfaces (108, 109) are adjacent to the left shoulder regions (110, 111) and right shoulder regions (112, 113) on the left side surfaces (106, 107) and right side surfaces.

[0056] The limiting carrier 95 includes a mounting portion 96 fixed to the lateral carrier 67 of the frame 64, and first and second side portions 97 and 98, which define a first and second limiting opening 114 and 115. The limiting openings 114 and 115 are defined by inner and outer limiting ends 116 and 117, respectively, as well as lower and upper limiting ends 120 and 121 and 122 and 123. The mounting portion 96 also includes a notch 124 through which the first portion 82 of the rail 75 passes.

[0057] In the assembled state, rail 75 is positioned within limit carrier 95 such that limit cam 100 projects through limit opening 114 and limit cam 101 projects through limit opening 115, but shoulder areas 110, 112 and 111, 113, or left side surfaces 106, 107 or right side surfaces 108, 109, or lower surface 102, 103 or the opposite upper surface do not come into contact with the corresponding limiting ends of limit openings 114, 115. At the same time, first portion 82 of rail 75 projects through notch 124, and mounting portion 78 is located rearward of mounting portion 96 and rearward of lateral carrier 67 and is fixed to vertical carrier portion 77.

[0058] That is, the limiting cams (100, 101) of the rail (75) protrude freely and without collision through the limiting openings (114, 115) as long as no force is acting on the rail (75), i.e., as long as the base unit (73) is in the operating position and is not subjected to any undesirable force, as also shown in Figure 3(c).

[0059] In contrast, when the base unit (73) moves outward away from the working position along the first portion (82) of the rail (75), the vertically elastically designed rail (75) moves downwards (based on the principle shown in FIG. 1(a)) until the lower surfaces (102, 103) of its limiting cams (100, 101) abut against the lower limiting ends (120, 121) of the limiting openings (114, 115), so that the limiting carrier (95) and, via it, the lateral carrier (67) take up the weight of the base unit (73), and the rail (75) is connected to the frame (64) by the gravitational force of the base unit (73).

[0060] It is also different when a horizontally acting force acts on the base unit 73 and threatens to rotate the container 54 around its axis 35. In this case, the rail 75 rests in the left (110, 111) or right (112) shoulder area against the corresponding end of the limiting opening 114, 115, so that this force is absorbed by the limiting carrier 95 or the frame 64, and therefore the suspension 80 of the weighing unit 50 is only stressed to the intended extent.

[0061] The same applies to all other forces acting on the base unit, which, if they cause the rail (75) to displace in any direction, will cause the limiting cams (100, 101) to collide with the corresponding ends (116 to 123) of the openings (114, 115), so that these forces are transmitted via the limiting carrier (95) to the lateral carrier (67), i.e., the frame (64), without causing excessive stress on the suspension (80).

[0062] As a result, the intermediate spaces between the limit cams (100, 101) and the limit openings (114, 115) need only be large enough for the suspension (80) to withstand, without damage, the movement of the rail (75) until the limit cams (100, 101) contact the limit openings (114, 115). It can be seen that the limit device (34) preferably comprises a limit carrier (95) fixed relative to the frame (64) and having openings (114, 115), the ends (116 to 123) of which form limit stops for the limit cams (100, 101) provided on the rail (75).

[0063] FIG. 4 shows a perspective view from above of an embodiment for the parallel arm (71) of the weighing unit (50) (FIG. 3(a)). The parallel arm (71) is made of an elastically deformable material, such as sheet metal, and has a rectangular body (120) with connecting tongues protruding from the body in the area of ​​its four corners, which are aligned parallel to each other and function as leaf springs (121, 121', 122, 122') with screw holes (123) at their ends, which can be fastened to the frame (64), the vertical frame section (70), or a suitably designed transition section (140) in contact with the container (54) (see FIG. 3(a)). The leaf springs (121, 121') are bolted to the frame section (70), and the leaf springs (122, 122') are bolted to the transition section (140). The leaf springs (121, 121', 122, 122') function as joints of the parallel arms (71) so that the required vertical movement of the container 54 is possible in a feasible manner by specific dimensioning. As mentioned above, the dimensioning depends on the type of weighing scale used and can be easily performed by a person skilled in the art. In the case of a vibrating wire weighing scale, the required vertical movement of the container (54) is in the region of a fraction of a millimeter, but is nevertheless essential to prevent the upward support force of the frame part (70) from falsifying the weight measured by the weighing scale (68).

[0064] The parallel arm (71) further has laterally folded reinforcing areas (125, 125') on the sides between the leaf springs (121, 122) and between the leaf springs (121', 122'), which reinforcing areas (125, 125') stiffen the parallel arm (71) in a defined manner between each leaf spring, so that its body (120) acts as a rigid lever attached to the frame and to the container (54) via the joints formed by the leaf springs (121, 121', 122, 122').

[0065] The lower parallel arm (72) (FIG. 3(a)) is designed similarly to the upper parallel arm (71).

[0066] It can be seen that the parallel arms (18, 19, 71, 72) preferably have joints designed as leaf springs (121, 121', 122, 122').

[0067] Figure 5 shows a further embodiment of a parallel arm (130), which is basically designed similarly to the parallel arms (71, 72), but in which the body (131) has a notch (132) across its entire width up to the folded reinforcement area (133, 133'), and the body (126) is divided into two parallel strips (134, 135) across the width of the parallel arm (130), which are connected to each other by the folded area (133, 133'). The dashed portion of the folded area (133, 133') between the strips (134, 135) shown in Figure 5 now functions as a vertical-horizontal leaf spring (136, 136'), which allows the strips (134, 135) to move relative to the horizontal according to the double arrow shown.

[0068] The parallel arms (130) therefore allow not only the vertical movement of the container 54 required by the weighing scale (68), but also its lateral movement. This is generally necessary when the vertical frame section (70) and the container axis (35) (see FIG. 3(a)) are not exactly parallel, but overlap to some extent. While this is rare with the weighing unit (50) according to FIGS. 3(a) to (d), it may be necessary, especially when the container rests on two scales rather than one, and the support points of the two scales form a three-point support with the parallel guides. In this case, since the support points of the two scales cannot be at exactly the same height, the container will be slightly tilted relative to the vertical and therefore slightly tilted relative to the parallel guides. In this case, the parallel arms (130) can tolerate a slight lateral deviation of the container area they support.

[0069] Again, lateral deviations, typically in the millimeter range, must necessarily be tolerated depending on the type of weighing scale used. If parallel guides guided the container exactly vertically, the load on one of the two weighing scales would increase and the load on the other would decrease because, depending on their initial position, the scales would not be at exactly the same height. An overloaded weighing scale would operate outside its intended operating range, introducing unwanted hysteresis into the measurement signal, potentially falsifying the measurement results and reducing the quality of the weighing.

[0070] Consequently, preferably, the parallel arms (18, 19, 71, 72) further have at least one horizontally acting joint, which is preferably designed as a leaf spring (136, 136'), which is even more preferred in the case of a gravity measuring weighing unit in which two weighing scales are provided.

[0071] It should be noted here that the container can also be placed on three weighing scales, in which case the parallel guides are omitted but rails (25, 75) according to the invention are provided, preferably with limiting devices (34, 52). It should also be noted that the suspension preferably has a ball support that interacts with the weighing scale assigned to it and transmits the weight to be measured. At its upper end, which captures the weight, the weighing scale has a spherically designed surface that interacts, for example, with a slightly wider spherical or elliptical recess of the same shape on the cantilever (13, 69') (Figures 1(a) and 3(a)). This allows the cantilever to be moved slightly sideways relative to the weighing scale without affecting the accurate weight measurement.

[0072] The overall result of the present invention in all embodiments is a gravity measuring weighing unit for bulk material, the weighing unit comprising a container for the bulk material to be weighed and a base unit with a horizontally arranged conveyor for the bulk material, the container and the base unit being removable from each other for maintenance, at least one weighing scale arranged thereon in such a way that the weighing unit is designed for gravity measuring weighing, and further comprising a frame operably supporting the weighing device via a suspension, the suspension being connected to the container of the weighing unit and supporting the weighing unit via the container, the container having rails protruding away from the container, and the base unit having a support structure running on the rails so that it can move back and forth between an operating position and a maintenance position.

Claims

1. A gravity measuring weighing unit for bulk materials comprising a weighing device (2, 55), The metering device (2, 55) comprises a container (3, 54) for the bulk material to be metered; a base unit (4, 73) comprising a non-vertically arranged conveyor for bulk material; the container (3, 54) and the base unit (4, 73) are detachable from each other for maintenance; the weighing unit (1, 50) comprises a frame (16, 64) on which at least one weighing scale (14, 68) is arranged and which operably supports the weighing device (2, 55) via a suspension (12) so that the weighing unit (1, 50) is configured for gravimetric weighing; the suspension (12) is connected to the container (3, 54) of the weighing unit (1, 50) and supports the weighing device (2, 55) via the container (3, 54); A gravity measuring weighing unit, characterized in that the container (3, 54) has a rail (25, 41, 75) protruding away from the container, and the base unit (4, 73) has a support structure (28, 83) running on the rail so that it can move back and forth between an operating position and a maintenance position.

2. 2. The gravity measuring and weighing unit according to claim 1, wherein a limiting device (34) is provided on the frame (16), the limiting device (34) limiting the rotation of the container (3) relative to the frame (16) about a vertical axis.

3. 3. Gravity measuring and weighing unit according to claim 2, wherein the limiting device (34) is connected to the frame (16) and has stops (33, 33') cooperating with the rails (25).

4. 2. The gravity measuring and weighing unit of claim 1, wherein the rail (25) is designed to be elastic in the vertical direction, and a support (32) is provided on the frame (16), and when the base unit (4) is in the maintenance position, the rail (25) is on the support (32), and when the base unit (4) is in the operating position, the rail (25) is on the support when the elastic deflection is downward so that the rail (25) is not on the support (32).

5. 2. The gravity measuring and weighing unit according to claim 1, wherein the rail (41) is designed in several parts, the container-side part (42) is connected to the container (3) and the frame-side part (44) is connected to the frame (16), the parts (42, 44) of the rail (41) are adjusted to each other and are relatively movable, and the support structure (28) is movable through an intermediate space (45) between the adjusted ends.

6. 3. Gravity measuring and weighing unit according to claim 2, characterized in that the limiting devices (34) have laterally cooperating stops at the adjusted ends of the rails (41).

7. A gravity measuring weighing unit as described in claim 6, wherein the stop portion is an alternating interlocking protrusion (47) or a sharp point (46).

8. A gravity measuring weighing unit as described in claim 1, wherein the rail (75) has a portion (82) extending away from the container (54) and a second portion (81) bending successively relative to the first.

9. A gravity measuring weighing unit as described in claim 1, wherein the rail (75) is designed as a double rail having two individual rails extending sideways adjacent to each other and positioned at a short distance from each other.

10. A gravity measuring weighing unit as described in claim 1, wherein the suspension (12) comprises parallel guides (17) having parallel arms (18, 19, 71, 72), the parallel guides (17) being connected at one end to the frame (16) and at the other end to the container (3) in a manner in which the container (3) is suspended, and the container (3) is movable vertically relative to the frame (16).

11. A gravity measuring weighing unit as described in claim 2, wherein the limiting device (34) is fixed to the frame (64) and comprises a limiting carrier (95) having openings (114, 115), the ends (116 to 123) of which form limiting stops for limiting cams (104, 105) provided on the rail (75).

12. A gravity measuring weighing unit as described in claim 10, wherein the parallel arms (18, 19, 71, 72) have joints designed as leaf springs (121, 121', 122, 122').

13. A gravity measuring weighing unit as described in claim 10, wherein the parallel arms (18, 19, 71, 72) further comprise at least one horizontally moving joint.

14. A gravity measuring weighing unit as described in claim 13, wherein the horizontally moving joint is designed as a leaf spring (136, 136').

15. A gravity measuring weighing unit as described in claim 1, wherein the support structure (83) is designed so that the base unit (73) can rotate relative to the rail (75).

16. A gravity measuring weighing unit as described in claims 9 and 13, wherein the support structure (83) comprises a mast (89) protruding between the individual rails (85, 86).

17. A gravity measuring weighing unit as described in Claim 16, wherein the support structure (83) further comprises a sliding disc (89) on the individual rails (85, 86).

18. A gravity measuring weighing unit as described in claim 1, which is equipped with two weight scales.

19. A gravity measuring weighing unit as described in claim 1, which is provided with three weight scales.

20. A gravity measuring weighing unit as described in claim 1, wherein the suspension has a ball support portion that cooperates with an associated weigh scale to transfer the weight to be weighed.

Images