RU2805059C2 - Device for grinding bulk loaded material - Google Patents

Abstract

FIELD: grinding devices.

SUBSTANCE: device contains a housing, the first and the second grinding tools located inside the housing, which are opposed to each other with an axial gap to form a grinding zone. At least the first grinding tools carry out a rotational movement. In this case, the first grinding tools are fixedly mounted on the first tool holder, and the second grinding tools are fixedly mounted on the second tool holder. Moreover, on the contact surface between the first tool holder and the first grinding tools and/or on the contact surface between the second tool holder and the second grinding tools there are channels for passing process gas. The channels each have an inlet opening located radially on the inside, through which process gas enters the channels, and an outlet hole located radially on the outside, through which the process gas exits the channels.

EFFECT: device provides improved cooling of the grinding zone.

14 cl, 5 dwg

Description

The invention relates to a device for grinding bulk loading material according to the restrictive part of paragraph 1 of the formula.

Devices of the type named at the beginning are characterized by an air-conducting mode of operation, in which air, together with the loaded material in the form of a gas-solid mixture, is axially introduced into the grinding space and, after radial deflection due to the centrifugal force, enters the annular grinding gap formed by the grinding tools. After grinding there to the desired size, a sufficiently thin material emerges radially from the grinding gap and is collected in an annular channel running along the perimeter between the housing and the grinding tools, from where it is tangentially carried out of the device in the air flow.

In this case, the energy introduced during grinding is largely converted into heat. The reason for this is the frictional, shearing and impact forces to which the feed material is exposed during grinding and which manifest themselves primarily in the area of the grinding tools. In the case of a thermally insensitive (heat-resistant) feed material, the device of the type makes do with the inherent (immanent) flow of its own air in order to cool the grinding tools so much that a negative impact on the grinded material is eliminated.

Problems regularly arise when heat-sensitive feed material must be crushed. In particular, when shredding plastics with a low softening point, the user of the type of equipment faces a difficult task. On the one hand, the grinding of the feed material must take place just below the softening temperature in order to achieve the highest possible throughput. However, if the material-dependent temperature limit is exceeded, the feed material softens and melts with the consequence that the individual particles agglomerate (stick together) and as a result the size of the fractions and the fractional composition of the final product are no longer in the desired range. On the other hand, particles heated above the maximum temperature stick (cook) to the machine parts and, in particular, to the grinding tools, so that, among other things, both the productivity of the machine and the quality of the final product suffer.

This problem is further amplified in the fine and ultra-fine grinding of heat-sensitive materials, as it has been found that the finer the final product produced, the greater the power required to complete the grinding work and the greater the heat generated in the area of the grinding tools.

To eliminate excess thermal stress on the feed material during grinding, one known measure is to reduce the productivity of the grinding devices. As a result, less grinding work is carried out per unit time and thus less excess heat is produced. However, in this case one has to put up with the fact that the grinding device is not fully loaded, which contradicts the fundamental requirement for the economical operation of such devices.

To solve this problem, DE 10 2010 049 485 A1 proposes to conduct additional cooling air into the grinding space through the opening of the housing in order to cool the device and the crushed material. By properly directing the cooling air inside the device, effective cooling of the grinding area is achieved without negatively affecting the performance of the machine.

Against this background, the invention aims to further improve known grinding devices with regard to cooling the grinding zone.

This problem is solved by a device with the features of paragraph 1 of the claims.

Preferred embodiments follow from the dependent claims.

The invention is characterized by the fact that the process gas, regardless of the material flow, is supplied directly to the grinding tools. If the process gas serves to cool the grinding tools, then by direct contact of the process gas with the grinding tools, excessive heat generation in this area is extremely effectively counteracted. Since the process gas is directed independently of the material flow, it is possible to control the action of the process gas by adjusting the amount of process gas per unit time without changing the gas-solid mixture at the entrance to the grinding zone. The invention thus opens up the possibility of further optimization of the grinding mode. Thus, thanks to the invention, it is possible to load the device according to the invention as much as possible and, by supplying a suitable amount of process gas, to prevent the material-dependent temperature limit from being exceeded. This offers significant economic advantages for the user of the device according to the invention.

Preferably, the process gas and the material stream are brought together downstream of the grinding zone, wherein the process gas and the material stream are mixed. If the process gas is an inert gas, this can reduce the risk of explosion. By using conditioned gas, such as conditioned air, the temperature and humidity of the final product can be influenced. If suitable substances are mixed with the process gas, color, odor, durability, processability, etc. may be affected.

In one simple embodiment of the invention, the process gas at the end of the channels is introduced through radially oriented outlets into an annular space that surrounds the grinding zone of the device according to the invention. However, in contrast to this, it is preferable for the said channels - which initially extend radially from the inside to the outside - to be deflected in the end region in the axial direction, so that the outlet openings are axially directed. In this case, the process gas exiting in the axial direction from the outlet holes crosses the material flow radially leaving the grinding zone. The resulting turbulence (swirls) promotes intense heat exchange between the material flow and the process gas and, in addition, performs additional grinding work, which counteracts the unwanted formation of agglomerates (unwanted agglomeration).

The geometry of the channels is chosen so that the flow rate of the process gas is high enough to remove excess (excessive) heat. However, at the same time it is required that the contact time be long enough so as not to harm the heat transfer from the grinding tools to the process gas flow.

To enhance the effect of the process gas on the grinding tools and on the feed material, one improvement of the invention proposes introducing additional process gas into the annular space between the circumferential wall of the housing and the grinding tools. For this purpose, for example, one or more process gas-loaded inlets that terminate into the annular space may be located on the circumferential wall of the housing, on the rear wall of the housing, or on the front wall of the housing. Preferably, two or more inlets are provided, wherein at least one inlet ends in an upper portion of the annular space located above the horizontal dividing plane through the axis of rotation, and at least one inlet terminates in a lower portion of the annular space located below the dividing plane.

Below, the invention is described in more detail on the basis of the exemplary embodiment shown in FIGS. 1-5, and other features and advantages of the invention will also be disclosed. The subject of the exemplary embodiment is a disc mill, but is not limited to it. Also included within the scope of the invention are, for example, refiners, rod mills and the like.

Shown:

Fig. 1 is an oblique view of the front side of a device according to the invention;

FIG. 2 is an oblique view of the rear side of the device shown in FIG. 1;

Figure 3 is a vertical section of the device shown in Figures 1 and 2;

Figure 4 is a partial cross-section of the area indicated in Figure 3 by the symbol IV on an enlarged scale; And

FIG. 5 is an oblique view of a partial area of a tool holder according to the invention with grinding tools arranged thereon.

FIGS. 1 to 3 show the basic structure of a device according to the invention in the form of a disk mill 1. The disk mill 1 has an essentially drum-shaped housing 3 surrounding an axis 2 with a front wall 4, a rear wall 5 axially spaced from it and connecting the front wall 4 and the rear wall 5 with a circumferential (side) wall 6, which together surround the grinding space 7.

In the area of the axis 2, the rear wall 5 has a housing hole 8, coaxial to the axis 2, through which the end of the drive shaft 9 of the drive unit passes. In the present embodiment, the drive shaft 9 is formed directly by the rotor shaft of the electric motor 10, but can also, as an independent shaft, be driven indirectly through a belt drive or other transmission. Through an annular flange 11 concentrically surrounding the opening 8 of the housing, the gear 3 is rigidly connected to the electric motor 10, which, in turn, rests on a stationary base 12.

As can be seen, in particular, in Fig. 4, on the part of the drive shaft located inside the housing 3, a round rotor disk 13 sits without the possibility of rotation, on the inner side of which facing the grinding space 7, in the area close to the axis, transport strips extending radially to the axis 2 are fixed. 14. In the region of their outer periphery, the rotor disc 13 on its inner side has an extension 15 extending coaxially around the axis 2 to receive a first tool holder 16 designed in the form of an annular disc. With part of its rear side facing the rotor disk 13, the first tool holder 16 is located in a form-fitting manner in said extension 15. Its opposite front side has an annular groove 33 extending coaxially around the axis 2, in which the first grinding tools 17 are located. The rotor disk 13 and the first holder The 16 tools can also be made in one piece, which reduces installation costs and assembly tolerances.

As shown in particular in FIGS. 1 and 3, the housing 3 on its front wall 4 has another circular housing opening 18 concentric with respect to the housing axis 2, which can be closed by a rotating housing door 19. The housing door 19 includes a ring-shaped door frame 10, which is connected to the housing 3 through a hinge 21 and rotated around a vertical axis. The door frame 20 accepts a stator disc 22 in the form of an annular disk with the possibility of axial displacement, for which the door frame with its inner perimeter forms a sliding support for the outer perimeter of the stator disk 22. The relative position of the stator disk 22 relative to the door frame 20 can be adjusted and fixed by means of three adjustment lead screws 23.

The stator disk 22 in its center has a loading hole 24 coaxial to the axis 2, to which a vertical inlet 25 for material is adjacent on the outside of the housing through a rounded arc. The loading opening 24 expands inward in the form of a funnel along the thickness of the stator disk 22. Facing the grinding space 4, the inner side of the stator disk 22 has a groove-like expansion 26 coaxially surrounding the axis 2, which is defined to receive a second tool holder 27, which also extends coaxially and is made in the form of an annular disk. . Facing the grinding space 7, the inner side of the second tool holder 27, in turn, has an annular groove 34 coaxially surrounding the axis 2, in which the second grinding tools 28 are located. Like the already mentioned rotor disk 13 and the first tool holder 16, the stator disk 22 and the second tool holder 27 can also be made in one piece.

The first grinding tools 17 and the second grinding tools 28 are thus axially opposed to each other by their grinding internal sides to form a grinding zone 29 formed as an annular gap.

Loading of the disk mill 1 with the loaded material 61 is carried out through the input 25 for the material, which through the loading hole 24 is directed axially in the center into the grinding space 7. There it enters the inner side of the rotor disk 13, where it is deflected in the radial direction and accelerated by the transport bars 14 k grinding zone 29. The grinding work is carried out in the interaction of the rotating first grinding tools 17 with the stationary second grinding tools 28, which experience significant heating. After their grinding, the material particles enter radially into the annular space 30 between the circumferential wall 6 of the housing and the rotor disk 13, where they are directed in the air flow to the material outlet 31 protruding tangentially from the housing 3 and are removed from the disk mill 1 in the form of the final product 57.

In addition, the disc mill 1 is equipped with a device for supplying process gas 32 to the grinding tools 17 and grinding tools 28, which will be explained in more detail below, especially with reference to FIGS. 4 and 5. As process gas 32 in the present embodiment, cooling air to counteract excessive heating of the grinding tools 17, 28. This is achieved by the process gas 32 being conducted directly along the rear sides of the first grinding tools 17 and the second grinding tools 28.

For this purpose, annular grooves 33, 34 are made in the tool holders 16, 27, which form a seat for the grinding tools 17, 28, in a manner that follows from a joint consideration of FIGS. 4 and 5. Due to the identical design in the features essential to the invention the image according to Fig. 5 applies to both the first tool holder 16 and the second tool holder 27 .

The annular slots 33, 34 are each limited by a slot bottom 35, which lies in a vertical plane to an axis 2 extending perpendicularly from the slot bottom 35 radially by an inner slot wall 36 and extending perpendicularly from the slot bottom 35 by a radially outer slot wall 37. In this case, the inner wall 36 of the groove and the outer wall 37 of the groove extend coaxially to the axis 2. The axial depth of the annular grooves 33, 34, respectively, the axial height of the walls 36, 37 of the groove is preferably in the range between 10 mm and 15 mm and in this case is 13 mm. The radial width R of the annular grooves 33, 34 is preferably in the range between 60 mm and 100 mm and in this case is 85 mm.

The first and second grinding tools 17, 28 may be formed by tool rings, or, as in the present embodiment, by grooved wedges 62, which are arranged in annular grooves 33, 34 in a row without gaps to form a ring. In both cases, the grinding tools 17, 28, with their flat rear sides, lie flat against the bottom 35 of the groove.

The bottom 35 of the groove for forming the radially arranged channels 38 has several groove-shaped recesses extending radially relative to the axis 2. The channels 38 extend from the outer wall 37 of the groove through at least half the radial width R of the bottom 35 of the groove, preferably the radial length l of the channels 38 lies between 50% - 70% of the length R of the annular grooves 33, 34. Therefore, the radial inner end of the channels 38 lies in the half of the annular disk-shaped groove bottom 35 close to the axis, whereby the channels 38 extend radially completely through the radially outer half of the annular disk-shaped groove bottom 35. This ensures that at least the outer circumferential region of the grinding tools is effectively cooled, while the inner circumferential region can be cooled even less strongly. The depth t of the channels 38 perpendicular to the bottom 35 of the groove is preferably between 1.5 mm and 4 mm and in this case is 2.5 mm.

The mutual average distance between the channels 38 in the circumferential direction with respect to the center axis is designated "a". Preferably, this average distance a is in the range between 30 mm and 50 mm and in this case is 40 mm. Also related to the circumferential direction, the width b of the individual channels 38 is at least 40% of said distance a and is preferably in the range between 60% and 70% of said distance a.

In the continuation (extension) of the channels 38, the outer wall 37 of the groove has a correspondingly axially extending recess 39, which continues the channel 38 in the region of the outer wall 37 of the groove and with its free end forms an axially directed outlet opening 40. In this case, the flow cross-section in the region of the recess 39 is the same or larger than the flow cross-section in the area of the channel 38. At the opposite inner end of the channels 38, one passage groove 41 with an inlet hole 42 to the channel 38 ends, respectively, crossing the tool holders 16, 27. This passage groove 41 reaches the rear side of the tool holders 16, 27, and the end of the groove there is offset radially outward relative to the inlet hole 42 (Fig. 4).

In the case of one embodiment not shown, the free edge of the outer groove wall 37 in the region of the axially directed flow outlets 40 is suitably positioned further rearward so that the process gas 32, as it exits, fans out into an axially to radially directed gas flow.

As can be seen in particular from FIG. 4, the device for supplying the first grinding tools 17 with process gas 32 includes two openings 43 in the rear wall 5 of the housing 3, which lie diametrically opposite on the peripheral circle around the axis 2. On the outer side of the rear wall 5, the openings 43 are adjacent to an inlet pipe 44 with an integrated control element, such as a damper (valve), which (the pipes) are configured to be loaded with process gas 32 through a pipe system not shown.

On the opposite inner side of the rear wall 5, an air guide annular disk 45 coaxially surrounding the axis 2 is fixed, the outer diameter of which is designed so that the air guide annular disk 45 with its outer perimeter passes radially beyond the openings 43, and its inner diameter is designed so that the air guide annular disk 45 with its internal perimeter overlaps radially with the rotor disk 13. On the side of the air guide annular disk 45 facing the rear wall 5 there is a first circumferential groove, the width of which extends in the radial direction from the openings 43 to the area of overlap with the rotor disk 22 and which, together with the rear wall 5, forms the first annular channel 46. A second circumferential groove is provided on the opposite side facing away from the rear wall 5. The second groove in relation to the first groove is significantly narrower and is located in the radial direction in the area of overlap with the rotor disk 13, with which it jointly forms a second annular channel 47. The first groove and the second groove and thereby the first annular channel 46 and the second annular channel 47 are connected to each other in the axial direction by means of several through splines 52, which extend in the plane of the air guide annular disk 45 in an arcuate manner around axis 2.

For a gas-tight (sealed) connection of the rotor disk 13 to the air-guide annular disk 45, a dynamic seal is provided on the surfaces of both disks 13, 45 facing each other in the overlap area. For this purpose, the air guide annular disk 45 has an annular groove 48 radially outer with respect to the second annular channel 47 and an annular groove 49 radially inner, and the rotor disk 13 on the corresponding peripheral circles has a radially outer annular rib 50 and a radially inner annular rib 51, which are included each type of labyrinth seal into the outer annular groove 48, respectively, the inner annular groove 49.

The rotor disk 5 in its outer circumferential area is pierced by connecting grooves 53, each of which, with its end emerging on the inner side of the rotor disk 5, is coaxial with the passage grooves 41 in the first tool holder 16, and the opposite open end of which communicates with the second annular channel 47.

The process gas 32 arriving through the inlet pipes 44 is evenly distributed in the first annular channel 46 formed by the first groove and the rear wall 5, from where it enters the second annular channel 47 through the passage slots 52 and is distributed there along its entire perimeter (volume). The second annular channel 47 supplies synchronously (simultaneously) all the connecting passages 53 with process gas 32, which through the passage passages 41 and inlet holes 42 enters the channels 38, flows through them first radially outward and then axially before it exits axially through the outlet holes 40 from channels 38.

The supply of the second grinding tools 28 is carried out in a corresponding manner, for which the stator disk 22 on its outer side has a third annular channel 54 coaxially surrounding the axis 2, into which two inlet pipes 55 end, which are diametrically opposed and are loaded with process gas 32. In addition, The stator disk 22 has a number of obliquely extending connecting grooves 56, which correspond to the connecting grooves 53 located on the rotor side and which are each coaxial with the passage grooves 41 in the second tool holder 27.

The process gas 32 supplied to the inlet pipes 55 is evenly distributed in the third annular channel 54, from where it simultaneously enters all the connecting grooves 56 and then into the passage grooves 41. Through the inlet holes 42, the process gas 32 flows through the channels 38, first in the radial and then in the axial direction before it exits axially through the outlet openings 40.

To ensure that the device 1 according to the invention is loaded with additional process gas 58, in particular cooling air, FIG. 2 shows an upper inlet 59 located in the rear wall 5 of the housing 3 and a lower inlet 60 located in the rear wall 5 of the housing 3, both of which end axially in an annular space 30. The upper inlet 59 lies above the horizontal dividing plane across the axis of rotation, and the lower inlet 60 lies below this dividing plane. Preferably, both inlets 59 and 60 are located diametrically opposite to the axis 2. Inlets 59 and 60 can also be located in the front wall 4 of the housing 3 or in the circumferential wall 6 of the housing.

Claims (14)

1. A device for grinding the loaded product with first grinding tools (17) and second grinding tools (28) located inside the housing (3) coaxially to the axis (2), which are opposed to each other at an axial distance from each other to form a grinding zone (29) and of which at least said first grinding tools (17) carry out a rotational movement around an axis (2), with the first grinding tools (17) being fixedly mounted on the first tool holder (16), and the second grinding tools (28) on the second holder (27) of the tool, characterized in that on the contact surface between the first tool holder (16) and the first grinding tools (17) and/or on the contact surface between the second tool holder (27) and the second grinding tools (28) there are channels (38 ) for passing process gas (32) with an inlet hole (42) located radially on the inside, through which the process gas (32) enters these channels (38), and with an outlet hole (40) located radially on the outside, through which the process gas (32) leaves these channels (38). 2. Device according to claim 1, characterized in that the channels (38) extend radially, the length of the channels (38) corresponding to at least half the radial length of the first grinding tools (17) and/or the second grinding tools (28). 3. Device according to claim 1 or 2, characterized in that the first tool holder (16) and/or the second tool holder (27) have an axially extending circumferential wall (37) which at least partially engages the first grinding tools (17) from behind ) and/or second grinding tools (28) along their outer periphery, the channels (38) correspondingly extending axially beyond the wall (37). 4. A device according to one of claims 1 to 3, characterized in that the first tool holder (16) and/or the second tool holder (27) has through grooves (41), each through groove (41) on one side of the tool holder ends in a channel (38), and on the other side of the tool holder has the ability to load process gas (32). 5. Device according to one of claims 1 to 4, characterized in that the channels (38) are formed by recesses in the first tool holder (16) and/or recesses in the first grinding tools (17) and/or by recesses in the second holder ( 27) tools and/or second grinding tools (28). 6. A device according to one of claims 1 to 5, characterized in that the first tool holder (16) is coaxially mounted on a rotor disk (13) rotating around an axis (2) of rotation, which has connecting grooves (53), each connecting groove (53) on one side of the rotor disk ends in a bore (41) in the first tool holder (16), and on the other side of the rotor disk it has the ability to be loaded with process gas (32). 7. A device according to one of claims 1 to 6, characterized in that the second tool holder (27) is coaxially mounted on a stationary stator disk (22), which has connecting grooves (56), with each connecting groove (56) on one side The stator disk ends in a passage groove (41) in the second tool holder (27), and on the other side of the stator disk it has the ability to load process gas (32). 8. Device according to one of claims 1 to 7, characterized in that the channels (38) each directly or indirectly through one or more annular channels (46, 47, 54) can be loaded with process gas (32). 9. Device according to claim 8, characterized in that the rotor disc (13) is gas-tightly connected to the housing by means of a dynamic seal, preferably via a labyrinth seal (48, 49, 50, 51), and an annular channel (47) is located inside the labyrinth seal. 10. Device according to claim 8 or 9, characterized in that another annular channel (54) is located in the stator disk (22). 11. Device according to one of claims 8-10, characterized in that the annular channels (46, 47, 54) are designed to be loaded with process gas (32) through the control element. 12. Device according to one of claims 1 to 11, characterized in that the rotor disk (13) and the first tool holder (16) and/or the stator disk (22) and the second tool holder (27) are made in one piece. 13. Device according to one of claims 1 to 12, characterized in that the first grinding tools (17) and/or the second grinding tools (28) are formed by a plurality of annular segments (62), and preferably one is matched to each annular segment (62). channel (38). 14. A device according to one of claims 1 to 13, characterized in that the housing (3) has at least one inlet for supplying additional process gas, which ends in the annular space (30), which is formed between the housing (3) and the rotor disk (13), respectively stator disk (22).