Patent Grant
10974252
This application is the National Phase of PCT Application No. PCT/EP2017/025058, filed Mar. 24, 2017, which claims the benefit of German Patent Application Serial Nos. 102016003493.9 and 102016013022.9, filed with the German Patent and Trade Mark Office on Mar. 24, 2016 and Nov. 2, 2016, respectively.
The invention relates to a comminution device for laboratory operation, particularly a laboratory mill, especially particularly a centrifugal mill, with a milling tool arranged in a milling chamber, with a housing assembly and with a milling material channel running through the housing assembly into the milling chamber for supplying milling material to the milling chamber and/or discharging milling material from the milling chamber, in particular wherein the milling material channel during milling operation is open to the environment and/or can be opened, especially particularly for successively supplying a milling material to the milling chamber during the milling operation. Moreover, the present invention relates to a damper as a separate component for use in a comminution device of the aforementioned type.
Comminution systems develop periodic sound emissions due to the comminution processes that take place during the milling process. These signals, coupled to the rotational speed of the comminution system, are very disturbing due to the usually high speeds in laboratories.
With centrifugal mills, this leads to strong impacts during the milling process due to high centrifugal forces acting on the parts being crushed by a fast-rotating milling tool. As a result, the equipment parts of the mill surrounding the milling chamber are excited to vibrate so that air and vibration noise emissions emanate from the milling chamber. The total sound energy radiated from the comminution device is about 30% discharged over the surfaces of the housing to the environment, while about 70% is emitted as sound via the feed and discharge openings of the comminution device.
Sound emissions are based on vibrations of the ambient air, which reach the environment through a milling material channel through which the milling material is supplied to and/or removed from the milling chamber from the comminution device and as such can directly reach the human ear. If the milling material channel is open during the milling operation for successively supplying the milling material to the milling chamber, there is a continuous sound path between the emission source in the area of the milling tool and the environment of the comminution device. Furthermore, vibration emissions occur based on shocks and vibrations of equipment parts of the comminution device directly or indirectly surrounding the milling chamber. These equipment parts can cause ambient air to vibrate and thus amplify sound emissions from the milling material channel. In addition, the vibrating machine parts in turn cause adjacent equipment parts to vibrate, with the result that the adjacent equipment parts also create noise.
To reduce sound emissions it is already known from the prior art to equip the housing parts of comminution devices with sound-absorbing materials. However, a complete encapsulation of the comminution device by a soundproof enclosure is not possible if the milling material channel must be open to supply or remove milling material during the milling operation.
The object of the present invention is to provide a comminution device of the type mentioned that has a greatly reduced sound radiation in the comminution and milling operation. The invention in particular is based on the object of reducing sound emissions that emerge as noise through the milling material channel or are transmitted through the housing and/or device parts of the comminution device forming the milling material channel and/or adjoining them in a simple and inexpensive manner in terms of equipment, wherein, preferably, supplying a milling material to the milling chamber and if necessary removing a milling material from the milling chamber are possible during the milling operation.
The invention solves this task with a comminution device of the type mentioned above, such that in the area of the milling material channel at least one system is present for passive reduction of sound emissions. The invention is based on the principle of damping noise development transmitted in particular as sound through the milling material channel during operation of the comminution device. Moreover, the invention preferably also addresses the reduction of vibration emissions that emanate from the housing and/or device parts surrounding the milling material channel. Through the system according to the invention, compared with a comminution device otherwise designed identically that does not have such a device a noise reduction of preferably at least 10 dB(A), more preferably at least 20 dB(A), particularly preferably more than 30 dB(A) or greater is achieved.
The above object is also achieved by a damper as a separate device part for use in a comminution device for laboratory operation, the damper being designed as a muffler for reducing sound emissions in particular.
A system according to the invention for reducing sound emissions can be a separate damper connected with the comminution device if needed. Alternatively or additionally, however, the housing and/or device parts of the comminution device forming the milling material channel and/or adjoining it can also be created by a particular housing and/or device geometry for passive reduction of sound emissions. The invention particularly addresses the problem of sound emissions through the milling material channel that can be open for supplying or removing milling material during the milling operation. In particular, the system according to the invention for passive reduction of sound emissions should allow an unhampered supply or removal of milling material during the milling operation and not close the milling material channel to the environment.
The measures proposed and described below according to the invention for passive reduction of noise emissions in the area of the milling material channel can be combined with measures known inherently from the prior art for sound insulation of the housing of the comminution device, so that an even greater reduction of noise emissions is achievable.
In particular, the comminution device according to the invention can be, for example, a centrifugal mill designed as rotor mill with a rotor that can be coupled to a drive motor as milling tool. The comminution device can also be designed as a jaw crusher, cutting mill, vibration disc mill, ball mill or knife mill.
The milling material channel passes through at least one housing part of the housing assembly and/or at least one separate component connected with the housing assembly. For example, a milling material hopper of the comminution device can be formed by a housing wall of the device lid that surrounds the milling material channel. A tubular material inlet can be connected with the housing lid, with the housing lid itself forming a milling material hopper and the milling material channel extending through the material inlet and the milling material hopper to the milling chamber. This is shown and described, for example, in EP 0 727 254 A1.
To simplify feeding of the milling material, the free cross-section of the milling material channel can taper funnel-shaped to the milling chamber so that the milling material feed to the milling chamber can occur successively in small amounts, especially through a feed system such as a vibrating chute or the like.
The milling material channel can also be formed and/or bounded by a separate component with, in particular, a funnel-shaped inner contour, connected, for example, with a housing part of the comminution device. For example, it is described in DE 100 66 027 A1 that a separate component forming the milling material channel is firmly screwed to a housing lid of the comminution device.
What is more, a funnel-shaped inlay can be inserted into the milling material channel to simplify the material feed to the milling chamber and enable easy cleaning by replacement of the inlay.
In a preferred embodiment of the invention, a separate damper is used for passive reduction of sound emission in the milling material channel. The damper forms a hollow body, causing partial reflection of sound waves through a suitable cross-section geometry of the inside of the damper. Passage through the muffler can cause an averaging of the sound pressure amplitude, resulting in a reduction of sound pressure peaks. Reflections can be created in the muffler by baffles and cross-sectional expansions and narrowings. The operating principle is based on partial reflection of sound waves from cross-sectional and directional changes, and optionally the generation of higher modes of jumps in the flow guidance in the damper. If a jump-like change in the free cross-section occurs due to the flow guidance through the damper, reflections and higher modes can occur at this jump level causing additional damping. In principle, the damper can also be designed as a resonance silencer. An air flow is induced in conjunction with an acoustic mass for the resonance. Energy is withdrawn from the sound field in the area of the resonance frequency. Counter-waves can be generated by the arrangement of differs ent baffle plates, with the goal of cancelling the sound waves to be damped.
A separate damper can be inserted into a milling material hopper of the comminution device in the area of the milling material channel. The damper can be detachably connected nondestructively with the milling material hopper. An embodiment is also possible and advantageous in which the damper above a milling material hopper is set on a housing of the comminution device and separably attached to the housing. The damper can thus be removed as needed; for example, for a cleaning or replacement. To further reduce the creation of sound emissions during milling operation, it is advisable to largely exclude relative movements between the damper and the housing and/or device parts of the comminution device forming the milling material channel and/or adjoining it through the type of connection of the damper with the comminution device.
In an alternative embodiment of the invention, the walls of the housing surrounding, forming or bounding the milling material channel, or separate components connected with the housing and at least partly forming the milling material channel, can have a damper geometry and as such create a damper integrated into the device architecture for passive reduction of noise emissions by at least partial reflection of sound to cross-sectional and/or directional changes in the damper. For example, a milling material hopper of the comminution device can be designed as integrated damper and have a structural design that contributes to a passive reduction of sound emissions. In the alternative embodiment described, no separate damper is inserted into the milling material channel; instead, the inner contour of the housing and/or device parts of the comminution device forming and/or bounding it is structurally designed such that the milling material channel as such is characterized by cross-sectional and/or directional changes that can lead to a damping by partial reflection of sound waves.
The following statements apply to both an embodiment of the invention with a separate damper and an embodiment of the invention with a damper integrated into the device architecture.
The supply or removal of the milling material to and from the milling chamber preferably occurs through the damper, where an air exchange between the milling chamber and the environment of the comminution device is possible. A simple milling material sups ply and/or removal can be assured through a suitable structural design of the damper.
The damper can be closed on the shell side, so that no sound can escape from the damper on the side into the environment.
If the damper is formed as a separate component, in the condition when in use the damper with its outer shell surfaces can lie directly against a housing wall surrounding the milling material channel and/or an adjacent part forming the milling material channel so that air passage between the damper and the adjacent wall is impeded. For example, the damper can be inserted into a milling material hopper of the comminution device and when in use then lies with its outer shell surfaces directly against the milling material hopper.
For a milling material inlet or outlet to and from the milling chamber through the damper, on the front side on its proximal end facing the milling chamber and its distal end facing away from the milling chamber the damper can have an opening, where preferably two central openings are provided on opposite ends of the damper and arranged coaxially. The opening at the proximal end of the damper may have a larger cross-section than the opening at the distal end of the damper. The opening at the proximal end of the damper has a flow exchange with the milling chamber and the opening at the distal end has a flow exchange with the environment. With the exception of the two openings the damper can preferably be formed fully closed. The smaller opening at the distal end of the damper contributes to the least possible sound emission into the environment.
To cover the input opening of the damper as needed and thus close the milling material channel if no supply or removal of milling material is necessary, a preferably insulated lid is provided.
Particularly preferred is a decentralized or eccentric supply of the milling material to the damper. For this purpose the milling material can be supplied through a feed trough that on the side gives the milling material a funnel geometry formed by the damper. The funnel geometry then causes the milling material to slide farther down in the direction of the milling chamber. The feed chute can be guided through a cover of the damper so that sound then escapes only through the feed chute. Through a rotatable arrangement of the cover of the damper, it can be possible to turn the outer opening of the feed chute to a side facing away from the user and thus direct the exit of sound emissions to this side.
Apart from that, with the damper an eccentric feed of the milling material to a milling material hopper of the comminution device can also be possible. For this purpose the damper can have a hopper part, the outlet opening of which is arranged above the milling material hopper. The outlet opening of the hopper part can be arranged eccentric to the milling material hopper so that the milling material is supplied through the hopper part to the inclined inlet surfaces of the milling material hopper and not in the center to the milling material hopper. Through a rotatable arrangement of the hopper part, it is possible to change the position of the outlet opening of the hopper part relative to the milling material hopper and thus the location of the milling material supplied to the milling material hopper in the circumferential direction of the inclined inlet surfaces of the milling material hopper.
Starting from its proximal end the damper can have at least one constant, i.e. continuous or discrete, i.e. discontinuous cross-sectional change in the distal direction. The cross-sectional change produces reflections of the sound waves with the damping effect described above. In particular, the damper in the distal direction has at least one constant or discrete cross-sectional expansion. For example, the damper cross-section from the proximal end of the damper in the distal direction through a first, proximal damper portion can be constant and in a subsequent, second distal damper portion can steadily increase. The first, proximal damper portion then has a cylindrically shaped inner surface and a second, distal damper portion has a conical or truncated cone-shaped inner surface. In the transition area of two portions with different cross sections, the cross-sectional change can be formed constant or also discontinuous or discrete in the form of a gradation. Alternatively, it is possible that the first, proximal damper portion has a conical inner surface, where the damper cross-section in the distal direction can steadily increase or decrease through the first, proximal damper portion. The second, distal damper portion may also have a conical inner surface with a damper cross-section steadily increasing in the distal direction or the second damper portion can have a cylindrical inner surface. The cross-section increase can be linear through a portion of the damper in the distal direction or also increase in the distal direction of the damper so that the damper's inner surface preferably is curved outward.
Preferably, the damper at its distal end directed outward or to the environment when in use has a curved inner surface or deflector plate that inside the damper causes a sound reflection and, preferably, a directional deflection in the radial direction to the central longitudinal axis of the damper and/or in the proximal direction to the milling chamber. The reflection and directional deflection results in the damping effect described above.
Apart from that, the damper can form a funnel geometry as material inlet for the milling material, where distal wall surfaces of the damper on the damper inside can cause sound reflection, change of direction and deflection of sound waves back into the inside of the damper. Where the interior is passed through multiple times, this can greatly reduce sound pressure peaks. The funnel geometry at the distal end of the damper can have a central funnel neck formed coaxial to the central longitudinal axis of the damper and extending proximally into the interior of the damper relative to the distal end of the damper. The funnel neck is formed by a central opening at the head end of the damper. At the distal end of the damper, dead spaces or baffle spaces are created in which the sound waves are reflected and can be guided back in the direction of the milling chamber. It can be expedient if the damper at its head end is closed with the exception of a central opening and, preferably, has the contour of a semicircular torus in the longitudinal section.
The damper can have a proximal shell portion extending from the proximal end in the distal direction and possibly at least one further, distal shell portion distally subsequent to the proximal shell portion. A head portion can be provided at the distal end of the damper. Each shell portion can have one at least partially cylindrical and/or conical shell inner surface. With the exception of a central opening, the head portion can have a closed inner surface that is bent or angled relative to the shell surface in the radial direction to the central longitudinal axis. In the area of the central opening, the inner surface can then be bent, curved or angled inward in the proximal direction, also conical. At its distal end the damper can correspondingly form a funnel geometry. There is then a change of direction and deflection of sound waves inside the damper at the hopper surfaces back into the interior of the damper.
The damper can also be designed as a combined reflection and absorption muffler. For this purpose, the damper can have an at least partial liner and/or arrangement with a sound-absorbing material. The sound-absorbing material can preferably be provided inside at the distal end of the damper, where there is a change of direction and deflection of sound waves back into the interior of the damper. If at its distal end in the longitudinal section the damper has the contour of the semicircular torus, the sound-absorbing material can lie on the inside against the damper in the area between an outer wall of the damper and a funnel neck formed in the axial, middle area of the damper that extends proximally into the damper interior relative to the distal end of the damper.
At least in areas, the damper can be formed double-walled. An air layer between two adjacent walls of the damper can contribute to reducing sound emissions. The area between two adjacent walls of the damper can also be filled with a solid insulating material that contributes to reducing sound emissions.
In the connection area of a separate damper with the comminution device, a sealing means can be provided to prevent relative movements during the milling operation between the damper and housing and/or device parts of the comminution device and therefore creation of new sound emissions and/or an air passage, and thus the transmission of sound between damper walls and adjacent housing and/or device walls.
The cross-section geometry of a separate damper at least at the proximal end of the damper can be adapted to the cross-section geometry of a milling material hopper of the comminution device. With a funnel-shaped milling material inlet or outlet, the damper at its end can also be formed correspondingly funnel-shaped so the damper can be easily and if necessary positively and/or non-positively inserted into the milling material hopper, and the most full-area arrangement of the damper against the milling material hopper possible achieved.
The housing and/or device parts of the comminution device forming and/or bordering the milling material channel can likewise have an insulation with a sound-absorbing material for passive reduction of sound emissions. Housing and/or device parts that form the milling material inlet and/or the milling material outlet can be formed sound-absorbing. A sound-absorbing material can be, for example, insulation made of rock wool, mineral wool, glass wool, glass fibers or foams. To receive the sound-absorbing material, a double-wall design of the housing and/or device parts of the comminution device forming and/or bordering the milling material channel can be provided. An encapsulation of the insulating material is then possible so that a contamination by the milling material is excluded.
The damper may be of metal, especially stainless steel, but also from polyurethane, polyethylene or a hard silicone material, or comprise the aforementioned materials. Particularly preferably, however, the parts of the damper that come into contact with the milling material are of stainless steel. In particular, with a separate damper this can possibly also consist of a soft insulating material or the like. Such a material offers a high inner insulation especially against high frequencies and ones thus experienced as particularly unpleasant. This may be a non-elastic, almost gel-like material that opposes hardly any restoring force to an active force. Such a material is characterized by a high impact strength. A soft polyurethane, a thermoplastic polyethylene, or a hard silicone material enter into consideration, for example. It should be possible to process by means of injection molding methods to enable inexpensive production of the damper. If the damper is designed as disposable or single-use, the need for cleaning the damper when the filling material is changed is eliminated. To reduce the soiling tendency of the damper on its inside, the inner surface of the damper can have a low roughness and a low wettability, as observed with the lotus plant (the lotus effect). Through self-cleaning abilities of the inner surfaces of the damper the soiling tendency can be greatly reduced, thus increasing the damper's useful life until a renovation, cleaning or replacement of the damper is required.
The damper can preferably be formed as several parts and/or capable of being taken apart. This creates the possibility of easy cleaning of the damper. Several parts of the damper may be joined together by being twisted or plugged to each other. With an integrated damper, access to its interior in particular can occur by partial dismantling of the housing assembly. With a separate damper, it can be easily taken out of the milling material channel and then disassembled and cleaned.
It is understood that the features of the invention's embodiments described above can be combined with each other as needed, even if this is not expressly described in detail. The paragraph formatting chosen does not exclude a combination of the invention features described in individual paragraphs.
In the following, preferred embodiments of the invention will be explained in more detail with reference to schematic drawings. For functionally similar features the same reference numbers are used.
As shown in
The milling material feed into the milling chamber 3 occurs through a milling material hopper 11, which is formed by a wall of the housing lid 10 and forms or borders a milling material channel 12 of the comminution device 2. The milling material channel 12 is connected with the milling material inlet opening 9 and therefore with the milling chamber 3. The milling material channel 12 is open to the environment during the milling operation. This enables a successive feed of the milling material to the milling chamber 3 during the milling operation.
To house the comminution device 2 at least one housing 13 is additionally provided, which can also be designed in multiple parts. The closure downward is formed by a base plate 14.
For passive reduction of noise emissions, the muffler 1 shown in
As emerges in particular from
The damper 1 is closed on the shell side and the front side at its lower, proximal end 16 and at its upper, distal end 17 each has a central opening 18, 19. The outlet opening 18 and inlet opening 19 are arranged coaxially in the embodiment shown. The outlet opening 18 preferably has a larger cross-section than the inlet opening 19.
Damper 1 can have a wall designed as one part or multiple parts with a proximal shell or damper portion 20, a distal shell or damper portion 21 subsequent to it distally, and a distal head portion 22. For an effective sound reduction the clear damper cross-section going from the proximal end 16 of damper 1 in the distal direction can be constant over the proximal damper portion 20 and steadily increase in the subsequent distal damper portion 21.
At the head portion 22 and distal end 17 of damper 1 is provided an inner surface 23, which causes a directional deflection for sound in the radial direction toward the central longitudinal axis 1 of damper 1 and in the axial direction toward milling chamber 3. This results in directional deflection of the sound waves in the area of the distal end 17 of damper 1, as schematically shown in
The proximal damper section 20 comprises on the inside a cylindrical shell surface 25, which transitions to a conical shell surface 26 in the distal damper portion 21. The distal damper portion 25 is followed by the head portion 22, the distal inner surface 23 of which is curved or angled relative to shell surface 26 of distal damper portion 21 in the radial direction toward the central longitudinal axis Y. In the area of opening 19 of distal end 17 of damper 1, the inner surface 23 can then be curved or bent or angled inward in the proximal direction, also conical. This creates a funnel geometry at distal end 17 of damper 1, which forms a funnel neck 27, which extends relative to the distal end 17 of damper 1 proximally into the interior of damper 1. The distal inner surface 23 in the longitudinal section has approximately the contour of a semicircular torus.
As is apparent from
It is not shown that damper 1 may also be designed double-walled to reduce sound emissions even more. A sound-absorbing material can be inserted between two walls of damper 1. With a double-walled structure of damper 1, an air layer between two adjacent walls of damper 1 can also already contribute to a reduction of noise emissions.
It will be understood that a corresponding insulation 28 in principle can also be provided in other areas of damper 1. Moreover, the possibility exists of encapsulating an insulating material toward the interior of damper 1 to prevent soiling of the insulating material by the milling material.
It will further be understood that damper 1 can also have an inner contour that differs from the inner contour shown in
Furthermore, damper 1 is preferably also designed as multiple parts so that, for example, head portion 22 of damper 1 can be detached from the shell portions 20, 21. This simplifies cleaning of damper 1. But damper 1 can also be designed as one-piece.
In particular, damper 1 may be made of stainless steel or also of plastic, and can be formed as an injection molded part.
Milling material hopper 11 can also be insulated with a sound-absorbing material for passive abatement of noise emissions.
It is understood that the centrifugal mills shown in
As also emerges from
In
Also in agreement, the two dampers 1 shown in
The damper 1 may be formed integrally. At the hopper outlet, the damper 1 shown in
A backsplash guard at damper 1 can also be formed by a separate conical body, which can be arranged through corresponding retaining elements or retaining portions of damper 1 above a hopper inlet or at the hopper outlet of damper 1.
The damper 1 shown in
Above the hopper inlet of damper 1, at its proximal end insert 36 has a conical wall portion 34 as backsplash guard, connected integrally through wall portions 35 extended web-shaped in the axial direction with a funnel-shaped inlet portion 39 of insert 36. The milling material is supplied through insert 36 past the web-shaped wall portions 35 into the area between insert 36 and damper 1, and from there through outlet opening 18 to milling chamber 3.
As seen from
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 102016003493.9 | Mar 2016 | DE | national |
| 102016013022.9 | Nov 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/025058 | 3/24/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/162340 | 9/28/2017 | WO | A |
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|---|---|---|---|
| 3229921 | Hess | Jan 1966 | A |
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| 20190126285 | Janetta | May 2019 | A1 |
| 20190133378 | Kim | May 2019 | A1 |
| 20190160472 | Janetta | May 2019 | A1 |
| 20200055057 | Stahl | Feb 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 2650008 | May 1978 | DE |
| 3514919 | Oct 1986 | DE |
| 10066027 | May 2002 | DE |
| 0727254 | Feb 1996 | EP |
| S4887670 | Oct 1973 | JP |
| 2003010714 | Jan 2003 | JP |
| 2014113519 | Jun 2014 | JP |
| Entry |
|---|
| International Search Report for PCT/EP2017/025058 dated Aug. 31, 2017, 8 pages. |
| Written Opinion for PCT/EP2017/025058 dated Aug. 31, 2017, 8 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20190160472 A1 | May 2019 | US |
