EP3274112A1

EP3274112A1 - Molding sand cooler

Info

Publication number: EP3274112A1
Application number: EP16710969.3A
Authority: EP
Inventors: Andreas Seiler; Stefan Gerl; Feng Li
Original assignee: Maschinenfabrik Gustav Eirich GmbH and Co KG
Current assignee: Maschinenfabrik Gustav Eirich GmbH and Co KG
Priority date: 2015-03-23
Filing date: 2016-03-18
Publication date: 2018-01-31
Anticipated expiration: 2036-03-18
Also published as: TWI666076B; CA2976720A1; RU2672125C1; PT3274112T; ES2809499T3; DE102015104340A1; AR104036A1; CN107405679A; US10124399B2; US20180029108A1; ZA201706396B; EP3274112B1; JP2018510781A; KR20170130507A; KR101946425B1; JP6396606B2; HRP20201389T1; MX2017011867A; TW201641183A; BR112017018380B1

Abstract

The invention relates to a molding sand cooler having a sand chamber which has an air inlet, if necessary comprising a fan, for the supply of air into the sand chamber, and an air outlet, if necessary comprising a fan, for the extraction of air from the sand chamber. The problem addressed by the invention is that of providing an improved molding sand cooler in which the discharge of sand via the air outlet during the cooling operation is reduced considerably. This problem is solved in that a dynamic air separator that is rotatable about an axis is provided, which air separator is arranged in such a way that substantially the whole air stream leaving the sand chamber through the outlet is guided through the dynamic air separator.

Description

Molding sand coolers

The present invention relates to a device for cooling hot foundry mold sand. Such devices are also referred to as a molding sand cooler. Used foundry molding sand can be reused when processing foundry sand is recycled. For this it is necessary to cool the used sand.

Such a device is known for example from DE 1 508 698. The device described there consists of a mixing container and has two vertically arranged drive shafts, which carry a mixing tool. The foundry molding sand to be cooled is introduced into the mixing vessel on one side and removed on the other side. While the foundry sand to be cooled is in the device, the foundry sand is mixed by means of the mixing tools. In addition, the mixing container has an opening for supplying air directly at the container bottom in the container wall.

This device is an attempt to produce an air-flow, water-saturated mechanically supported fluidized bed to cool the by the previous casting process up to 150 ° heated foundry sand to the service temperature of about 45 ° C by means of evaporative cooling.

In a subsequent mixer, the appropriately cooled molding sand can be prepared with the addition of new sand, bentonite, carbon and water in the use state for subsequent use. The described cooling takes place in the prior art in various embodiments, which can be divided into continuous processes and discontinuous processes. Cooling drums, fluidized bed coolers or mixed coolers are used for this purpose, in which either molding sand to be continuously processed is fed or in which batchwise, i. discontinuously, the appropriate molding sand is supplied.

The coolers described have in common that the introduced into the cooler, generally in a sand chamber, hot and dry sand is moistened by spraying water and then cooled by passing through and passing large amounts of air utilizing the evaporative cooling of about 70 to 100 ° C to about 45 ° C.

The correspondingly cooled sand leaves the cooler with a moisture content of approx. 1 to 2%. The respective coolers generally have a sand chamber having an air inlet optionally with a fan for supplying air into the sand chamber and an air outlet optionally with a fan for sucking air from the sand chamber. Especially with the use of fluidized bed and mixing coolers, however, due to the turbulent turbulence of the sand to be cooled with the introduced gas stream solid particles of the particle bed snatched, which are discharged through the air outlet and then have to be deposited in downstream gas cyclones or filters, such as in the DE 199 25 720 has been described. The thus deposited solids are applied to the discharged, cooled sand and fed in the subsequent treatment process in a mixer.

However, to achieve effective cooling using evaporative cooling, very large amounts of gas flow must be passed through the molding sand. In the case of fluidized bed coolers, solids contents in the exhaust gas flow of up to 15% are determined in the exhaust gas flow due to the inherently very high flow velocities of the fluid into the sand bed to be fluidised. When using mixing coolers, a lower flow velocity is sufficient due to the mechanically generated fluidized bed, so that the solids discharge is lower, but still significant. In any case, however, a significant amount of sand is removed from the cooler and must be returned to the process in a separate step after appropriate cooling. This is basically undesirable.

Based on the described prior art, it is therefore an object of the present invention to provide an improved mold sand cooler in which the sand discharge during the cooling process through the air outlet is significantly reduced.

According to the invention this object is achieved in that a dynamic, about an axis rotatable air classifier is provided, which is arranged such that substantially the complete, the sand chamber exiting through the air outlet air flow is passed through the dynamic air classifier. A dynamic air classifier is constructed in such a way that a centrifugal force field is realized by it. The possibly laden with sand particles air is then sucked against the centrifugal force within the dynamic wind sifter. Therefore, it is possible with the help of an air classifier, if it is operated at a correspondingly high speed to remove the solid particles from the exhaust air stream, so that they can remain in the sand chamber or be returned to this.

In a preferred embodiment, the dynamic air classifier has a separator wheel which can be rotated about an axis of rotation and has an outlet which essentially surrounds the axis of rotation and which is connected to the air outlet and which has at least one inlet which is not arranged on the axis of rotation. For example, the classifier wheel can be cylindrical, conical or frustoconical, wherein the at least one inlet is arranged on the lateral surface of the separator wheel. As a rule, however, the classifier wheel has a plurality of inlet openings. For example, the lateral surface may have a plurality of holes. Alternatively, the classifying wheel may have a plurality of lamellae that are spaced apart from one another such that the inlets are formed by the spacing between the lamellae. The centrifugal force field is generated by the rotation of the classifier wheel, so that centrifugal force is exerted on all particles that are inside the classifier wheel. The centrifugal force is counteracted by the force that is exerted on the particles by the flow of air into the classifier wheel. Since the centrifugal force increases in proportion to the particle mass, particles with a certain limit size are rejected by the air classifier because for them the centrifugal force is greater than the force applied by the air flow.

Basically, coarse and fine material can be separated from each other with the aid of such a dynamic air classifier, since the fine material will overcome the centrifugal force and be guided by the air classifier, while coarse material will be rejected by the classifying wheel and fall back into the sand chamber.

The axis of rotation may be oriented vertically, horizontally or inclined relative to the vertical.

In a further particularly preferred embodiment, the molding sand cooler has at least two dynamic air classifiers, since it has been shown that the reduction of the sand discharge can be carried out more effectively with a plurality of air separators. Alternatively, of course, it would also be possible to make the single air classifier larger. However, the design of the sand blast machine with multiple air separators has proven to be more effective. For example, the molding sand cooler may have a molding sand inlet through which molding sand can be fed into the sand chamber and a molding sand outlet through which molding sand can be removed from the sand chamber, in which case one air classifier is best located closer to the molding sand outlet than the other air classifier. In particular, in the case of a continuous operation, the air classifiers may have a different size and / or be operated at different speeds in order to take into account the progressive cooling and the associated consistency change of the molding sand during the continuous cooling process. In a further preferred embodiment, it is provided that the molding sand cooler additionally has a static air classifier, preferably a deflecting separator. It is particularly preferred that the static air classifier is connected upstream of the dynamic air classifier. The static air classifier differs from the dynamic classifier in that the classifier is not rotated to create a centrifugal force field. Instead, for example, the gravitational force and the flow resistance caused by the air flow can provide for the separation of coarse and fines. Alternatively, a diverter can be used, which uses a separation by the inertial forces at a deflection. The flow follows the diversion so that in the area of the deflection inertial forces occur, which leads to a separation of coarse and fine material. In general, static air classifiers are not as effective as dynamic air classifiers. In particular, when very large amounts of sand are discharged with the air, the maximum capacity of a dynamic air classifier is reached quickly. By connecting a static air classifier, which already undertakes the presetting of coarse material, the dynamic air classifier can be relieved. In a particularly preferred embodiment, the molding sand cooler has a classifier chamber, in which the dynamic air classifier is arranged. In this case, the sand chamber is connected via a flow channel with the classifier chamber, wherein the cross section of the flow channel is smaller in the direction of the classifier chamber. Due to the narrowing of the flow cross section, the flow velocity increases. Advantageously, the flow channel is arranged in such a way that the fluid flow directed from the sand chamber into the classifier wheel via the flow channel is directed onto a wall of the classifier chamber and not onto the dynamic classifier. This causes a sharp deflection of the gas flow, since the air is sucked through the dynamic air classifier. In a further preferred embodiment, provision is made for the classifier chamber to be connected to the sand chamber via a return channel, wherein preferably a conveyor system, specifically a screw conveyor, is provided in order to convey bulk material accumulated on the bottom of the classifier chamber into the sand chamber. The fact that in the classifier chamber a static air classifier is realized, it comes to an accumulation of the bulk material, which was rejected by the two classifiers. This bulk material can be brought into the molding sand cooler. For this purpose, in addition to a conveyor system, for example, a flap or a double flap can be provided, with which the accumulated bulk material can be returned from the classifier chamber into the sand chamber. Particularly preferred is an embodiment in which a conveyor permanently or at regular intervals accumulated bulk material promotes the sand chamber. In a further preferred embodiment, a rotational speed device is provided for controlling or regulating the rotational speed of the dynamic air classifier. By changing the speed of the dynamic air classifier, the separation between coarse and fine material can be adjusted. The faster the air classifier turns, the more sand particles are rejected by the air classifier. Due to the operating principle of the air classifier, particles that exceed a certain limit size are rejected, while smaller particles can pass through the air classifier unhindered. The limit size can be adjusted by the speed. The higher the speed, the smaller the limit size and vice versa. Preferably, the rotational speed device is designed such that the rotational speed is so high that a complete separation of all particles in the sand chamber takes place.

In a further preferred embodiment, means may be provided for detecting the amount of airflow through the air outlet, wherein the detected amount of airflow is provided to the speeding device so that the speeding device may control or regulate the speed in dependence on the detected amount of airflow. The described limit size, ie the size to which particles are rejected by the air classifier, is determined not only by the speed of the air classifier, but also by the flow rate of the air flow from the air inlet to the air outlet. Therefore, for example, decreases the flow rate, the speed of the air classifier can be reduced, which saves energy. In particular when using a discontinuous molding sand cooler or batch molding sand cooler, the rotational speed device can also be designed such that the rotational speed is increased during the molding sand cooling. In particular, during the filling or emptying of the sand chamber to be cooled with molding sand, the speed can be reduced or even stopped the rotation. In the course of the molding sand cooling, the speed can then be increased and adapted to the different treatment phases. Furthermore, a device for detecting the particle discharge and / or the particle size distribution via the air outlet can be provided, wherein the detected particle discharge is made available to the rotational speed device so that the rotational speed device can be designed such that the rotational speed is controlled as a function of the detected particle discharge is regulated.

Furthermore, a device for supplying water into the sand chamber may be provided, wherein preferably a water control device is provided, to which the detected particle discharge and optionally the rotational speed of the dynamic air classifier are made available, and which is designed such that the supplied water quantity as a function of the detected particle discharge and possibly the rotational speed of the dynamic air classifier. Basically, the particle discharge detection here serves indirectly as a moisture measurement. The drier the sand in the cooler, the higher the discharge of solids through the wind vane. Therefore, if a high solids discharge is detected, this means that the sand is relatively dry and, if necessary, still water must be supplied.

In a further preferred embodiment, a moisture sensor for detecting the moisture of the sand in the sand chamber is provided, wherein preferably the moisture sensor is connected to the rotational speed device, and this is designed such that the rotational speed is regulated or controlled in dependence on the detected moisture , If a moisture sensor is present as described here, a particle discharge sensor does not necessarily have to be present in addition, because due to the relationship between moisture and particle discharge, the moisture sensor can also be used to control the rotational speed device.

In a further preferred embodiment, it is provided that the rotational speed device is designed such that it controls or regulates the rotational speed such that large particles whose grain size is greater than a predetermined marginal grain size are separated by the air classifier, while smaller particles having a particle size, which is smaller than the predetermined limit grain size, are withdrawn via the air outlet. Preferably, a size between 120 μιη and 10 μιη and more preferably between 30 μιη and 60 μιη is selected as the limit grain size.

By virtue of this measure, it is possible, for example, to remove only the aggregates, such as, for example, carbon and bentonite from the molding sand to be processed, while sand components remain in the molding sand. The thus recovered sand-free bentonite and carbon can be recycled in the subsequent treatment process. Further advantages, features and applications will become apparent from the following description of several preferred embodiments and the accompanying figures.

Show it:

FIG. 1 shows a schematic representation of a first embodiment of the invention,

FIG. 2 shows a schematic illustration of a second embodiment of the invention,

FIG. 3 shows a schematic representation of a third embodiment of the invention,

FIG. 4 shows a schematic representation of a fourth embodiment of the invention,

FIG. 5 shows a schematic illustration of a fifth embodiment of the invention,

Figure 6 is a schematic representation of a sixth embodiment of the invention

1 shows a first embodiment of a molding sand cooler 1 is shown. This has a sand chamber 2 and an air inlet 3 with a corresponding fan 4 and an air outlet 5 with a corresponding fan 6.

Furthermore, a molding sand inlet 7, via which molding sand to be cooled can be introduced into the sand chamber 2, and a molding sand outlet 8, can be removed from the chamber via the molding sand, are provided. Within the sand chamber 2, two motor-driven mixing tools 9 are arranged. In the upper wall of the sand chamber 2, the connection to the air outlet 5 is embedded. In this area, a dynamic air classifier 10 is arranged, which can be rotated about its vertical axis. The separator here consists of a substantially cylindrical wheel, on the lateral surface of a plurality of spaced-apart fins are arranged so that air can flow through the fins radially inwardly to be sucked through the air outlet 5.

Since, in operation, the dynamic air classifier 10 rotates about its vertical axis, for which purpose an engine 11 is used, a centrifugal field arises in the region of the laminations, which can only be overcome by particles which are smaller than a certain marginal particle size.

Furthermore, the embodiment shown has an air quantity sensor 14 with which the amount of air extracted via the air outlet 5 can be measured. In addition, a particle discharge sensor 13 is provided, which may be designed, for example, as a triboelectric filter monitor or particle counter or as an online particle size measuring device. In addition, a moisture sensor 15 is arranged in the area of the sand chamber 2. The sensors are all connected to a control and regulating unit 12, which evaluates the corresponding measurement signals and on the basis of the measurement, the speed of the motor 1 1 adjusts to set the desired limit grain size. FIG. 2 shows a second embodiment of the invention, which differs essentially from the embodiment of FIG. 1 in that here two dynamic air classifiers 10 'and 10 "are arranged, which are each connected to the air outlet 5 via separate supply lines dynamic air classifier 10 'is located closer to the molding sand inlet 7 than the other dynamic air classifier 10 ". In this embodiment, it can be seen that the shape of the dynamic air classifier can be chosen differently. While the air classifier 10 'has a truncated cone shape and also has lamellae, the dynamic air classifier 10 "is cylindrical again, but has a large number of holes in its lateral surface.

FIG. 3 shows a third embodiment of the invention. This differs from the previous embodiments substantially in that here two dynamic winders 10 "', which are of identical design, are connected to the air outlet via the same air outlet line 5.

FIG. 4 shows a fourth embodiment of the invention. Here, the classifier 10 is not arranged inside the sand chamber 2, but in a separate classifier chamber 16. The classifier chamber 16 is connected to the sand chamber 2 via a connection channel 17 tapering in the flow direction. Due to the tapered design of the connecting channel 17, the flow velocity of the air flow increases in the direction of the classifier chamber 16. By the arrangement shown here, a sharp deflection is formed at the end of the connecting channel 17, so that a portion of the sand, namely essentially the parts of the sand, which can not follow the air flow in the region of the sharp deflection due to the inertial forces on the wall 18 bounce off and slowed down. These sand particles then fall to the bottom of the classifier chamber 16. The remaining air-sand stream is then passed through the here about a horizontal axis rotating classifier 10, through which also sand parts whose diameter is greater than a marginal grain size, are rejected. The particles that are smaller are drawn off via the air outlet 5. The particles collecting at the bottom of the classifier chamber 16 are conveyed back into the sand chamber 2 with the aid of the conveyor system 17 designed as a screw conveyor.

In the figures 1 to 4 embodiments have been shown, in which the molding sand cooling can be done both continuously and discontinuously. In the discontinuous case, a certain amount of molding sand is introduced into the sand chamber 2, the molding sand is then cooled and the molding sand is then completely removed via the molding sand outlet 8, so that it can be fitted in the following step with the next sand mold. FIG. 5 shows a fifth embodiment in which the molding sand cooling takes place continuously. Here, a fluidized bed 19 is arranged in the interior of the sand chamber 2, so that molding sand, which is introduced via the molding sand inlet 7, is transported via the fluidized bed 19 gradually but continuously towards the molding sand outlet 8. During this transport, a large amount of air is supplied via the air inlet 3 into the sand chamber and discharged via the air outlet 5. Interposed is a dynamic classifier 10.

FIG. 6 shows a sixth embodiment of the invention. Based on this embodiment, the entire process of molding sand processing can be explained. Used molding sand 20 is introduced here via the molding sand inlet 7 into the sand chamber 2. The molding sand cooler here substantially corresponds to the embodiment of Figure 1, although a speed control is provided which makes a separation between coarse and fine material in accordance with the invention. The molding sand to be cooled in the sand chamber is optionally mixed with water and then flowed through with a large amount of air, which is introduced into the sand chamber 2 via the air inlet 3. The air is guided via the dynamic classifier 10, via the connecting line 25 and via a filter 23 via the air outlet 5. The classifier 10 is adjusted by means of the control device such that sand portions, i. Particles with a size greater than 100 μιη, is rejected by the classifier. Smaller particles, however, are allowed through by the classifier. These are essentially bentonite and carbon. These are filtered off in the filter 23 and guided into the weighing device 24. The amount of the deposited bentonite-carbon mixture in the weighing device 24 is measured and optionally corrected by adding new bentonite 21 or carbon 22. Once the molding sand is cooled within the sand chamber 2 to the desired temperature of about 45 °, the sand can be transferred via the molding sand outlet 8 in the weighing device 27. In the weighing device 27, bentonite and carbon in the desired composition can then be supplied via the weighing device 24. If necessary, new sand 20 must also be supplied. The resulting mixture is then fed to a treatment mixer 28 and, if appropriate, the water content of the molding sand in the treatment mixer 28 is adjusted via the water supply 29.

Claims

Patent claims

A molding sand cooler with a sand chamber having an air inlet optionally with a fan for supplying air into the sand chamber and an air outlet optionally with a fan for sucking air from the sand chamber, characterized in that a dynamic, rotatable about an axis Air classifier is provided, which is arranged such that substantially the complete, the sand chamber exiting through the air outlet air flow is passed through the dynamic air classifier.

2. The molding sand cooler according to claim 1, wherein the dynamic air classifier has a classifier wheel which is rotatable about an axis of rotation and has an outlet which essentially surrounds the axis of rotation and which is connected to the air outlet and which has at least one inlet which does not is arranged on the axis of rotation.

3. molding sand cooler according to claim 2, characterized in that the classifier wheel is cylindrical, conical or frusto-conical, wherein the at least one inlet is arranged on the lateral surface of the separator wheel.

4. molding sand cooler according to one of claims 2 to 3, characterized in that the axis of rotation is oriented vertically, horizontally or inclined relative to the vertical.

5. molding sand cooler according to one of claims 2 to 4, characterized in that the molding sand cooler, a molding sand inlet, can be supplied through the molding sand into the sand chamber, and a molding sand outlet, can be removed from the sand chamber via the molding sand, wherein at least two dynamic Wind sifter are provided, each having a rotatable about an axis of rotation Sichterrad, wherein preferably an air classifier is arranged closer to the molding sand outlet than the other air classifier.

6. molding sand cooler according to claim 5, characterized in that the two air classifier have drives which are designed such that the air classifier are operated in operation at different speeds.

7. molding sand cooler according to one of claims 1 to 6, characterized in that the dynamic air classifier, a static air classifier, preferably a Umlenkabscheider is connected upstream.

8. molding sand cooler according to claim 7, characterized in that the molding sand cooler has a classifier chamber, in which the dynamic air classifier is arranged, and the sand chamber is connected via a flow channel with the classifier chamber whose cross-section is smaller in the direction of the classifier chamber, wherein preferably the flow channel is arranged such that the directed from the sand chamber via the flow channel in the Sichterrad fluid flow is directed to a wall of the classifier chamber and not on the dynamic classifier.

9. molding sand cooler according to claim 8, characterized in that the classifier chamber is connected via a return channel with the sand chamber.

10. molding sand cooler according to claim 8 or 9, characterized in that a conveyor, and that is best provided a screw conveyor to promote accumulated on the bottom of the classifier chamber bulk material in the sand chamber.

1 1. molding sand cooler according to one of claims 1 to 10, characterized in that a rotational speed means for controlling or regulating the rotational speed of the dynamic air classifier is provided.

12. molding sand cooler according to claim 1 1, characterized in that a device for detecting the amount of air flow through the air outlet is provided, wherein the detected amount of air flow of the speed device is provided, wherein preferably the speed device is formed such that the speed in dependence on the controlled amount of airflow can be controlled or regulated.

13. molding sand cooler according to claim 1 1 or 12, characterized in that the molding sand cooler is a batch molding sand cooler, wherein the rotational speed device is designed such that the speed is increased during the molding sand cooling.

14. molding sand cooler according to one of claims 1 1 to 13, characterized in that a device for detecting the Partikelaustrags is provided via the air outlet, wherein the detected Partikelaustrag the speed device provided is preferably formed, wherein the rotational speed device is designed such that the rotational speed can be controlled or regulated in dependence on the detected particulate discharge.

15. molding sand cooler according to one of claims 1 1 to 14, characterized in that a device for supplying water is provided in the sand chamber, wherein preferably a water control device is provided, which the detected particulate matter and optionally the speed of the dynamic air classifier is provided , and which is designed such that the amount of water supplied in dependence on the detected particulate matter and optionally the speed of the dynamic air classifier takes place.

16. molding sand cooler according to any one of claims 1 1 to 15, characterized in that a moisture sensor is provided for detecting the moisture of the sand in the sand chamber, wherein preferably the moisture sensor is connected to the rotational speed device, and this is designed such that the speed in Depending on the detected humidity is controlled or controlled.

17. Form sand cooler according to one of claims 1 1 to 16, characterized in that the speed-limiting device is designed such that it controls the speed or controls such that large particles, such. Sand are separated by the air classifier, while smaller particles are taken off with a particle size of <100 μιη and preferably of <30 μιη through the air outlet.