MATERIAL CONVEYING DEVICE

Description

[0001] The invention relates to a material conveying device for feeding at least one injection molding and / or extrusion unit with a non-free-flowing or viscous material to be conveyed, comprising a filling hopper which is rotatable about an axis of rotation relative to a console and a conveyor screw which is rotatably arranged along an inner surface of the filling hopper in a screw shaft of the console and which is designed to convey the material to be conveyed from the filling hopper to an outlet, wherein the screw shaft is connected to a hopper outlet of the filling hopper, and wherein the filling hopper and the conveyor screw are drivable via at least one drive device, wherein the filling hopper is operable as a function of at least one operating parameter of the material conveying device.Furthermore, the invention relates to a method for feeding at least one injection molding and / or extrusion unit with a non-free-flowing or viscous material, with a material conveying device with a rotatable filling hopper with a conveyor screw which is rotatable about a rotation axis and arranged along an inner surface of the casing of the filling hopper and which is rotatably mounted, wherein the filling hopper and the conveyor screw are driven by at least one drive device, wherein the filling hopper is driven as a function of at least one operating parameter and the rotational movement is reduced or stopped when a limit value of the operating parameter is reached or exceeded.

[0002] Material conveying devices of the type mentioned with a rotating conical filling hopper and a conveyor screw mounted so as to be rotatable along a surface line are known from the documents EP 0 286 972 A2, EP 0 470 510 A2, EP 0 687 543 A2, EP 1 317 009 A2 and WO 2014 / 198 503 A1.

[0003] In EP 0 470 510 A2, a pressure sensor is arranged in the area of ​​the screw conveyor mouth to control the speed of the screw conveyor. A similar arrangement is known from EP 3 332 940 A1.

[0004] DE 10 2019 115 122 A1 describes a material conveying device for feeding an injection molding and / or extruder unit, comprising a hopper mounted rotatably about a rotation axis relative to a console, and a conveyor screw arranged rotatably along an inner surface of the hopper in a screw shaft of the console. The screw shaft is connected to the hopper outlet of the hopper. The hopper is operable depending on the drive torque of the hopper.

[0005] Especially with harder materials, irregularities in the material feed and thus high loads on the mechanical components can occur

[0006] The object of the invention is to achieve a constant discharge.

[0007] According to the invention, this is achieved in a material conveying device of the type mentioned at the outset in that a drive torque of the conveyor screw is selected as at least one operating parameter, wherein the drive torque is preferably determined by at least one torque transducer arranged in the drive path of the conveyor screw.

[0008] Harder materials in particular can lead to blockages in the screw conveyor or at the outlet of the material conveyor. This causes an increase in at least one operating parameter, such as the conveying pressure and / or the torque of the screw conveyor or the feed hopper, which can lead to greater stress on the mechanical and electrical components of the material conveyor. By reducing the speed of the feed hopper or stopping the feed hopper drive, the material feed is reduced and the stress is reduced. Only when a normal value of the operating parameter is reached is the speed of the feed hopper increased again or the feed hopper drive restarted.

[0009] In addition, the speed of the conveyor screw can also be reduced.

[0010] According to one embodiment of the invention, the reduction of the speed or the stopping of the drive of the filling hopper can be carried out by a clutch or slip clutch arranged in the drive train between the drive device and the filling hopper, which interrupts the drive connection to the filling hopper when the limit value of the operating parameter is reached or exceeded.

[0011] At least one further operating parameter can be a drive torque of the filling hopper. Advantageously, the drive torque can be determined by at least one torque sensor arranged in the drive path of the filling hopper.

[0012] Alternatively or additionally, it can be provided that at least one operating parameter is a current consumption of the drive device of the conveyor screw formed by an electric motor, wherein the current consumption can preferably be determined by an evaluation device.

[0013] Furthermore, it can be provided - alternatively or additionally - within the scope of the invention that at least one operating parameter is a conveying pressure of the material conveying device, wherein the conveying pressure can preferably be determined by a pressure sensor arranged in the region of the outlet.

[0014] One embodiment of the invention provides that the conveyor screw can be driven via a first drive device and the filling hopper via a second drive device, wherein preferably at least one drive device is formed by a speed-adjustable electric motor.

[0015] Preferably, the material conveying device has at least one electronic control unit which is designed to control at least one drive device and / or at least one shaft coupling in the drive train between the drive device and the conveyor screw and / or between the drive device and the filling hopper.

[0016] Advantageously, the material conveying device comprises a storage device for storing the defined limit value of the operating parameter and a comparison and evaluation device for comparing the current operating parameter with the defined operating parameter, wherein preferably the storage device and / or the comparison and evaluation device is / are integrated into the electronic control unit.

[0017] The electronic control unit is advantageously designed to reduce or interrupt the drive of the filling hopper when the defined limit value of the operating parameter is reached or exceeded.

[0018] Within the scope of the invention, it is further provided that at least one media feed channel opens into the screw shaft, wherein the opening of the media feed channel into the screw shaft is preferably arranged between the hopper outlet and an end of the conveyor screw facing the outlet. A particularly liquid, pasty, or free-flowing medium - for example, crosslinking agent, silicone oil, and / or coloring material - can be fed to the non-free-flowing or viscous conveying material via the media feed channel. In order to achieve the most homogeneous mixing possible of the non-free-flowing or viscous material with the medium, it is advantageous if at least one mixing device is arranged on the conveyor screw and / or downstream of the conveyor screw, wherein the mixing device is preferably arranged in the screw shaft.

[0019] To achieve the stated object, a method is provided according to the invention which provides that a drive torque of the conveyor screw is selected as at least one operating parameter, wherein the drive torque is preferably determined by at least one torque transducer arranged in the drive path of the conveyor screw.

[0020] Preferably, the limit value of the operating parameter is predefined and stored in a storage medium, a current operating parameter is determined and compared with the predefined limit value of the operating parameter, and at least one drive device of the filling hopper is reduced or stopped when the current operating parameter corresponds at least to the limit value of the operating parameter.

[0021] According to one embodiment of the invention, it is provided that a drive torque of the filling funnel is further selected as at least one operating parameter, wherein the drive torque is preferably determined by at least one torque transducer arranged in the drive path of the filling funnel.

[0022] Alternatively or additionally, it can be provided that a delivery pressure in the region of the outlet is selected as at least one operating parameter, wherein the delivery pressure is preferably measured by a pressure sensor arranged in the region of the outlet.

[0023] Furthermore, it can be provided - alternatively or additionally - that an intake current of the drive device of the conveyor screw is selected as at least one operating parameter, wherein the intake current is preferably detected by an evaluation device.

[0024] The invention is explained in more detail below with reference to the non-limiting embodiments shown in the figures. These schematically show: Fig. 1 shows a material conveying device according to the invention in a longitudinal section along the line I - I in Fig. 2 ; Fig. 2 the material conveying device in a side view; Fig. 3 a detail of the material conveying device in one embodiment; Fig. 4 a detail of the material conveying device in a further embodiment; Fig. 5 the method according to the invention in a first embodiment; Fig. 6 the method according to the invention in a second embodiment; and Fig. 7 the method according to the invention in a third embodiment.

[0025] The Fig. 1 and Fig. 2 show a material conveying device 1 according to the invention for the controlled feeding of a non-free-flowing or viscous-flowing, in particular plasticizable material, for example HTV (solid silicone), polyester-PMC, rubber and other "doughy" materials, to an injection molding and / or extrusion unit.

[0026] The material conveying device 1 has a stationary console 2, on which a filling hopper 4 is mounted for rotation about an axis of rotation 4a via at least one pivot bearing indicated by reference numeral 3. A conveyor screw 6 is arranged for rotation about an axis of rotation 6a in a screw shaft 5 of the console 2 along an inner surface 4b of the filling hopper 4, the screw shaft 5 being connected to a hopper outlet 4c of the filling hopper 4. The conveyor screw 6 is designed to convey the non-free-flowing or viscous material from the filling hopper 4 via an outlet channel 7 to an outlet 8 of the console 2. In the exemplary embodiment shown, the conveyor screw 6 is driven by a first drive device 9, and the filling hopper 4 is driven by a second drive device 10. The drive devices 9, 10 are formed, for example, by speed-controlled electric motors.

[0027] In the area of ​​exit 8, in Fig. 1 In the example shown, a pressure sensor 11 is arranged in a bore 12 connected to the outlet channel 7.

[0028] Reference numeral 13 designates a torque transducer arranged in the drive path of the conveyor screw 6 and / or in the drive path of the filling hopper 4.

[0029] The material conveying device 1 has an electronic control unit 14 which is designed to control at least one drive device 9, 10 and / or at least one - in Fig. 1 and Fig. 2 not further shown - shaft coupling in the drive train between drive device 9 and conveyor screw 6 and / or between drive device 10 and filling hopper 4. The electronic control unit 14 is connected - depending on the design - to at least one drive device 9, 10 and / or shaft coupling and / or a pressure sensor 11 and / or a torque sensor 13. Integrated into the electronic control unit 14, for example, is a memory device 15 for storing a defined limit value of the operating parameter and a comparison and evaluation device 16 for comparing a current operating parameter with the defined limit value of the operating parameter. The electronic control unit 14 is designed to reduce or interrupt the drive of the filling hopper 4 when the defined limit value of the operating parameter is reached or exceeded.At least one operating parameter can be formed by the drive torque of the conveyor screw 6 or the filling hopper 4, the conveying pressure of the material conveying device 1 or the current consumption of at least one drive device 9, 10 formed by an electric motor - for example the first drive device 9 for the conveyor screw 6.

[0030] Fig. 3 shows a console 2 of a material conveying device 1 in an embodiment according to the invention in a section analogous to Fig. 1 , wherein the console 2 has at least one media supply channel 17 opening into the screw shaft 5. The opening 17a of the media supply channel 17 into the screw shaft 5 is advantageously arranged between the hopper outlet 4c of the filling hopper 4 and the end 6b of the conveyor screw 6, which faces the outlet channel 7 or the outlet 8.

[0031] At least one liquid, pasty, or free-flowing medium, for example, crosslinking agent, silicone oil, and / or coloring material—in particular, at least one color paste—can be actively fed to the non-free-flowing or viscous conveying material via the media feed channel 17. To achieve thorough mixing of the medium with the non-free-flowing or viscous conveying material, at least one mixing device 18 is arranged in the region of the conveyor screw 6 and / or downstream of the conveyor screw 6, wherein the mixing device 18 is preferably arranged in the screw shaft 5—for example, in the region of the end 6b of the conveyor screw 6. The mixing device 18 is formed, for example, by a mixing disk 181 having a plurality of axial bores 183a. To improve mixing, a plurality of mixing disks 181, 182 can also be arranged one behind the other in the conveying direction.At least one mixing disc 181 can be connected to the conveyor screw 6 in a rotationally fixed and rigid manner or can be attached to the conveyor screw 6 in a floating manner. Instead of axial bores 183a or in addition to them, recesses 183b with various geometries can be arranged on the circumference of the mixing disc 181 (see . Fig. 4 ).

[0032] Fig. 4 also shows a console 2 of a material conveying device 1 in a further embodiment according to the invention in a section analogous to Fig. 3 , wherein the console 2 also has a media feed channel 17 opening into the screw shaft 5, wherein the mouth 17a of the media feed channel 17 is arranged between the hopper outlet 4c of the filling hopper 4 and the end 6b of the conveyor screw 6, which faces the outlet channel 7 or the outlet 8. The mixing device 18 is in Fig. 4 as a mixing attachment 180 at the end 6b of the conveyor screw 6, which is connected in a rotationally fixed manner to the conveyor screw 6. The mixing attachment 180 has a first mixing disc 181 and a second mixing disc 182 with recesses 183b on the circumference of the respective mixing disc 181, 182, with a screw-like mixing element 184 arranged between the mixing discs 181, 182 - as an extension of the conveyor screw 6. In other words, the conveyor screw 6 is interrupted and divided into two parts by the first mixing disc 181.

[0033] It is possible to operate the conveyor screw 6 as a dynamic mixer with an adjustable follow-up time after reaching a desired dosing quantity in order to improve the mixing of the conveyed material with the paint material.

[0034] Conveniently, the media supply through the at least one media supply channel 17 can be dependent on at least one conveying parameter of the material conveying device 1, for example, dependent on the speed of the conveyor screw 6 and / or the feed hopper 4 and / or the power consumption of the drive device 9, 10 of the conveyor screw 6 or the feed hopper 4. The conveying parameter can be different from or identical to the operating parameter of the material conveying device 1 used to operate the feed hopper 4. In the case of application on an extruder or an injection molding machine, the media supply can be dependent on the dosing volume or the shot weight of the injection mold.

[0035] For example, supplying a color material separately from the conveying material has the advantage that a uniform, transparent, neutral material can be used as the conveying material. This eliminates the need to keep a colored conveying material in stock for each color used, significantly reducing storage capacity for the conveying material.

[0036] For tempering the screw shaft 5 and the conveyor screw 6, cooling holes 24 for a cooling medium can be provided in the console 2 ( Fig. 4 ). Reference numeral 25 denotes connections for supply and discharge lines (not shown in more detail) for supplying and discharging the cooling medium.

[0037] The inventive method for the controlled feeding of solid silicone, polyester-PMC, rubber, and other "doughy" materials, particularly into an injection molding machine or extruder, provides for the force or speed of the conveyor screw 6 and / or the feed hopper 4 to be controlled, reduced, or stopped when a defined force acts on the material conveying device 1. This achieves a more consistent discharge rate—especially with harder materials—because the control ensures that conveying material is always available near the conveyor screw 6. Furthermore, this protects the mechanical system and / or enables smaller dimensions in the design of the mechanical system.

[0038] In the following, three embodiments of the method according to the invention are described, wherein separate drive devices 9, 10 are advantageously provided for the conveyor screw 6 and the filling hopper 4: 1. Variant: Measuring the current consumption (see Fig. 5):

[0039] In this variant, the current consumption of the electric motor 9a of the first drive device 9 of the conveyor screw 6 is measured and in step 20 (see Fig. 5 ) in the comparison and evaluation device 16 with a defined limit value stored in the memory unit 15 and evaluated. The current measurement can be carried out using an external current measuring unit or - if available - using a frequency converter of the electric motor of the conveyor screw 6. If the current consumption is higher than the stored defined limit value, then it can be deduced that the feed hopper 4 is pressing the material being conveyed in a circle too strongly against the conveyor screw 6. In this case, in step 21 the speed of the drive device 10 for the feed hopper 4 is regulated, throttled or stopped. This not only mechanically protects the conveyor screw 6 but also has the positive effect of ensuring that any lumps of material that may be present in harder materials remain close to the conveying position of the conveyor screw 6 and can be removed from there without delay. 2nd variant: mechanical slip clutch (see Fig. 6):

[0040] In this variant, a mechanical slip clutch 19 is installed between the second drive device 10 of the filling hopper 4 and the filling hopper 4 itself. If the material conveyed in the circulating manner in the filling hopper 4 is pressed too strongly against the conveyor screw 6, Fig. 6 In the step indicated by reference numeral 22, the slip clutch 19 becomes active and reduces or disconnects the drive torque for the feed hopper 4. As a result, the feed hopper 4 rotates more slowly or stops completely. This prevents excessive force from acting on the conveyor screw 6.

[0041] In addition to the mechanical protection of the conveyor screw 6, this also has the positive effect of ensuring that a lump of material present in harder materials remains close to the conveying position of the conveyor screw and can be removed from there without delay. 3. Variant: Torque transducer (see Fig. 7):

[0042] In this variant, a torque sensor 13 is installed between the conveyor screw 6 and the first drive device 9, which measures the torque. If excessive force is detected by this torque sensor 13, feedback is sent to the second drive device 10 of the feed hopper 4 in step 23.

[0043] In this case, the speed of the second drive device 10 of the filling hopper 4 is regulated, throttled, or stopped. This can be done by controlling the second electric motor 10a of the second drive device 10 or by controlling a controllable shaft coupling (not shown) in the drive train between the second drive device 10 and the filling hopper 4.

[0044] In addition to the mechanical protection of the conveyor screw 6, this also has the positive effect of ensuring that the lump of material present in harder materials remains close to the conveying position of the conveyor screw 6 and can be removed from there without delay.

Claims

1. Material conveying device (1) for charging at least one injection molding and / or extruding unit with a non-free-flowing or viscous material to be conveyed, having a feed hopper (4) rotatable around an axis of rotation (4a) relative to a console (2) and a conveyor screw (6) arranged in a screw shaft (5) of the console (2) so as to be rotatable along an inner lateral surface (4b) of the feed hopper (4), which is designed to convey the material to be conveyed from the feed hopper (4) to an outlet (8), wherein the screw shaft (5) is connected to a hopper outlet (4c) of the feed hopper (4), and wherein the feed hopper (4) and the conveying screw (6) are drivable via at least one drive device (9, 10), wherein the feed hopper (4) is operable as a function of at least one operating parameter of the material conveying device (1), characterised in that at least one operating parameter is a drive torque of the conveyor screw (6), wherein preferably the drive torque is determinable by at least one torque transducer (13) arranged in the drive path of the conveyor screw (6).

2. Material conveying device (1) according to claim 1, characterised in that the rotational movement of the feed hopper (4) can be reduced or stopped when a defined limit value, preferably an upper limit value, of at least one operating parameter is reached or exceeded.

3. Material conveying device (1) according to claim 1 or 2, characterised in that the rotational movement of the feed hopper (4) can be increased if a, preferably lower, defined limit value of at least one operating parameter is undershot.

4. Material conveying device (1) according to one of claims 1 to 3, characterised in that the material conveying device (1) has at least one electronic control unit (14) which is designed to control at least one drive device (9, 10) and / or at least one shaft coupling in the drive train between the drive device (9) and the conveying screw (6) and / or between the drive device (10) and the feed hopper (4).

5. Material conveying device (1) according to one of claims 1 to 4, characterised in that the material conveying device (1) has a memory device (15) for storing at least one defined limit value of the operating parameter and a comparison and evaluation device (16) for comparing a current operating parameter with the defined operating parameter, wherein preferably the memory device (15) and / or the comparison and evaluation device (16) are integrated in the electronic control unit (14).

6. Material conveying device (1) according to claim 4 or 5, characterised in that the electronic control unit (14) is designed to reduce or interrupt the drive of the feed hopper (4) when the defined limit value of the operating parameter is reached or exceeded.

7. Material conveying device (1) according to one of claims 1 to 6, characterised in that at least one switchable clutch or slip clutch (19) is arranged in the drive train between the drive device (10) and the feed hopper (4), which is designed to interrupt the drive connection to the feed hopper (4) when the defined limit value of the operating parameter is reached or exceeded.

8. Material conveying device (1) according to one of claims 1 to 7, characterised in that at least one operating parameter • is a drive torque of the feed hopper (4), wherein preferably the drive torque can be determined by at least one torque transducer (13) arranged in the drive path of the feed hopper (4), and / or • is a conveying pressure of the material conveying device (1), wherein preferably the conveying pressure can be determined by a pressure transducer (11) arranged in the region of the outlet (8), and / or • is a current consumption of the drive device (9, 10), which has an electric motor (9a, 10a), of the conveying screw (6) or of the feed hopper (4), wherein preferably the current consumption is determinable by a comparison and evaluation device (16).

9. Material conveying device (1) according to one of claims 1 to 8, characterised in that the conveying screw (6) can be driven by a first drive device (9) and the feed hopper (4) can be driven by a second drive device (10), wherein preferably at least one drive device (9, 10) has a speed-controllable electric motor.

10. Material conveying device (1) according to one of claims 1 to 9, characterised in that at least one media supply channel (17) opens into the screw shaft (5), wherein preferably the opening (17a) of the media supply channel (17) into the screw shaft (5) is arranged between the hopper outlet (4c) and an end (6b) of the conveying screw (6) facing the outlet (8).

11. Material conveying device (1) according to claim 10, characterised in that at least one mixing device (18) is arranged in the region of the conveying screw (6) and / or downstream of the conveying screw (6), wherein preferably the mixing device (18) is arranged in the screw shaft (5).

12. Method for charging at least one injection molding and / or extruding unit with a non-free-flowing or viscous material, having a material conveying device (1) with a rotatable feed hopper (4) having a conveying screw (6) arranged rotatably along an inner lateral surface (4b) of the feed hopper (4), wherein the feed hopper (4) and the conveyor screw (6) are driven by means of at least one drive device (9, 10), wherein the feed hopper (4) is driven as a function of at least one operating parameter and the rotary movement is reduced or stopped when a limit value of the operating parameter is reached or exceeded, according to one of claims 1 to 11, characterised in that a drive torque of the conveyor screw (6) is selected as at least one operating parameter, wherein preferably the drive torque is determined by at least one torque transducer (13) arranged in the drive path of the conveyor screw (6).

13. Method according to claim 12, characterised in that the limit value of the operating parameter is predefined and stored in a memory device (15), in that a current operating parameter is determined and compared with the predefined limit value of the operating parameter, and in that the speed of at least one drive device (9, 10) of the feed hopper (4) is reduced or stopped if the current operating parameter corresponds at least to the predefined limit value of the operating parameter.

14. Method according to claim 12 or 13, characterised in that further, as at least one operating parameter, • a drive torque of the feed hopper (4) is selected, wherein the drive torque is preferably determined by at least one torque transducer (13) arranged in the drive path of the feed hopper (4), and / or • a conveying pressure in the region of the outlet (8) is selected, wherein preferably the conveying pressure is measured by a pressure transducer (11) arranged in the region of the outlet (8), and / or • an input current of the drive device (10) of the conveyor screw (6) is selected, wherein preferably the input current is detected by a comparison and evaluation device (16).

15. Method according to one of claims 12 to 14, characterised in that that a coloring material is supplied to the non-free-flowing or viscous conveying material in the region of the conveying screw (6), wherein the non-free-flowing or viscous conveying material and the coloring material are mixed in the conveying screw (6) and / or downstream of the conveying screw (6).