MOLDING SAND COOLER

Abstract

The present invention concerns a casting sand cooler comprising a sand chamber having an air inlet optionally with a fan for the feed of air into the sand chamber and an air outlet optionally with a fan for sucking air out of the sand chamber. To provide an improved casting sand cooler in which the sand discharge during the cooling operation by way of the air outlet is markedly reduced, it is proposed according to the invention that a dynamic wind sifter which is rotatable about an axis and which is so arranged that substantially the complete air flow leaving the sand chamber through the air outlet is passed through the dynamic wind sifter.

Claims

1. A casting sand cooler comprising a sand chamber having an air inlet (3) and an air outlet (5), wherein the air inlet (3) has a fan for the feed of air into the sand chamber and/or the air outlet (5) has a fan for sucking air out of the sand chamber (2), characterised in that a dynamic wind sifter (10) which is rotatable about an axis and which is so arranged within the casting sand cooler and is operable such that substantially the complete air flow leaving the sand chamber (2) through the air outlet (5) is passed through the dynamic wind sifter (10) and solid particles are removed from the discharge air flow and remain in the sand chamber or can be at recycled thereinto.

2. A casting sand cooler according to claim 1 characterised in that the dynamic wind sifter (10) has a sifter wheel which is rotatable about an axis of rotation and which has an outlet which substantially surrounds the axis of rotation and which is connected to the air outlet (5), and which has at least one inlet not arranged on the axis of rotation.

3. A casting sand cooler according to claim 2 characterised in that the sifter wheel is cylindrical, conical or frustoconical, the at least one inlet being arranged at the peripheral surface of the sifter wheel.

4. A casting sand cooler according to claim 2 characterised in that the axis of rotation is oriented vertically, horizontally or inclinedly relative to the vertical.

5. A casting sand cooler according to claim 2 characterised in that the casting sand cooler (1) has a casting sand inlet (7) by way of which casting sand can be fed into the sand chamber (2) and a casting sand outlet (8) by way of which casting sand can be removed from the sand chamber (2), wherein there are provided at least two dynamic wind sifters (10) which respectively have a sifter wheel rotatable about an axis of rotation, wherein preferably one wind sifter is arranged closer to the casting sand outlet (8) than the other wind sifter.

6. A casting sand cooler according to claim 5 characterised in that the two wind sifters (10) have drives so designed that the wind sifters are operated in operation at differing rotary speeds.

7. A casting sand cooler according to claim 1 characterised in that a static wind sifter is disposed upstream of the dynamic wind sifter (10).

8. A casting sand cooler according to claim 7 characterised in that the casting sand cooler (1) has a sifter chamber (16) in which the dynamic wind sifter (10) is arranged and the sand chamber (2) is connected to the sifter chamber (16) by way of a flow passage whose cross-section becomes smaller in the direction of the sifter chamber (16).

9. A casting sand cooler according to claim 8 characterised in that the sifter chamber (16) is connected to the sand chamber (2) by way of a return passage.

10. A casting sand cooler according to claim 8 characterised in that there is provided a conveyor device (17) in order to convey loose material collected on the bottom of the sifter chamber (16) into the sand chamber (2).

11. A casting sand cooler according to claim 1 characterised in that there is provided a rotary speed device (12) for open-loop or closed-loop control of the rotary speed of the dynamic wind sifter (10).

12. A casting sand cooler according to claim 11 characterised in that there is provided a device (14) for detecting the quantitative air flow through the air outlet (5), wherein the detected quantitative air flow is made available to the rotary speed device (12).

13. A casting sand cooler according to claim 11 characterised in that the casting sand cooler (1) is a batch casting sand cooler, wherein the rotary speed device (12) is so adapted that the rotary speed is increased during the casting sand cooling operation.

14. A casting sand cooler according to claim 11 characterised in that there is provided a device for detecting the particle discharge by way of the air outlet (5), wherein the detected particle discharge is made available to the rotary speed device (12).

15. A casting sand cooler according to claim 11 characterised in that there is provided a device (29) for feeding water into the sand chamber (2).

16. A casting sand cooler according to claim 11 characterised in that there is provided a moisture sensor for detecting the moisture in the sand in the sand chamber (2), wherein the moisture sensor is connected to the rotary speed device and same is so designed that the rotary speed is subjected to open-loop or closed-loop control in dependence on the detected moisture.

17. (canceled)

18. A casting sand cooler according to claim 8 wherein the flow passage is so arranged that the fluid flow passed from the sand chamber by way of the flow passage into the sifter wheel is directed on to a wall of the sifter chamber (16) and not on to the dynamic sifter.

19. A casting sand cooler according to claim 12 wherein the rotary speed device is so adapted that the rotary speed is subjected to open-loop or closed-loop control in dependence on the detected quantitative air flow.

20. A casting sand cooler according to claim 14 wherein the rotary speed device is so adapted that the rotary speed is subjected to open-loop or closed-loop control in dependence on the detected particle discharge.

21. A casting sand cooler according to claim 15 wherein there is provided a water control device to which the detected particle discharge and optionally the rotary speed of the dynamic wind sifter (10) are made available and which is so designed that the fed amount of water is effected in dependence on the detected particle discharge and optionally the rotary speed of the dynamic wind sifter (10).

Description

[0031] Further advantages, features and possible uses will be apparent from the following description of a number of preferred embodiments and the accompanying drawings in which:

[0032] FIG. 1 shows a diagrammatic view of a first embodiment of the invention,

[0033] FIG. 2 shows a diagrammatic view of a second embodiment of the invention,

[0034] FIG. 3 shows a diagrammatic view of a third embodiment of the invention,

[0035] FIG. 4 shows a diagrammatic view of a fourth embodiment of the invention,

[0036] FIG. 5 shows a diagrammatic view of a fifth embodiment of the invention, and

[0037] FIG. 6 shows a diagrammatic view of a sixth embodiment of the invention.

[0038] FIG. 1 shows a first embodiment of a casting sand cooler 1. It has a sand chamber 2 as well as an air inlet 3 with a corresponding fan 4 and an air outlet 5 with a corresponding fan 6.

[0039] In addition there is a casting sand inlet 7 by way of which casting sand to be cooled can be introduced into the sand chamber 2 and a casting sand outlet 8 by way of which casting sand can be taken from the chamber. Arranged within the sand chamber 2 are two motor-driven mixing tools 9. The connection to the air outlet 5 is let in the upper wall of the sand chamber 2. Arranged in that region is a dynamic wind sifter 10 which can be rotated about a vertical axis. Here the sifter comprises a substantially cylindrical wheel, at the peripheral surface of which are arranged a plurality of mutually spaced plates so that air can flow radially inwardly through the plates in order to be sucked away by way of the air outlet 5.

[0040] As in operation the dynamic wind sifter 10 rotates about its vertical axis, for which purpose a motor 11 is used, a centrifugal force field is generated in the region of the plates, which force field can only be overcome by particles smaller than a given limit grain size.

[0041] In addition the illustrated embodiment has a quantitative air sensor 14 with which the amount of air sucked away by way of the air outlet 5 can be measured. In addition there is a particle discharge sensor 13 which for example can be in the form of a triboelectric filter monitor or particle counter or in the form of an online particle size measuring device. In addition a moisture sensor 15 is arranged in the region of the sand chamber 2. The sensors are all connected to an open-loop and closed-loop control unit 12 which evaluates the corresponding measurement signals and which on the basis of the measurement sets the rotary speed of the motor 11 to set the desired limit grain size.

[0042] FIG. 2 shows a second embodiment of the invention which differs from the embodiment of FIG. 1 substantially in that here two dynamic wind sifters 10 and 10 are provided, which are respectively connected to the air outlet 5 by way of separate conduits. The dynamic wind sifter 10 is arranged closer to the casting sand inlet 7 than the other dynamic wind sifter 10. It will be seen in this embodiment that the form of the dynamic wind sifter can be selected to be different. While the wind sifter 10 is of a frustoconical shape and also has plates the dynamic wind sifter 10 is again cylindrical but has a plurality of holes in its peripheral surface.

[0043] The geometry of the dynamic wind sifter can be adapted in dependence on the desired process implementation.

[0044] FIG. 3 shows a third embodiment of the invention. It differs from the previous embodiments substantially in that here two dynamic wind sifters 10' which are identical are connected to the air outlet by way of the same air outlet conduit 5.

[0045] FIG. 4 shows a fourth embodiment of the invention. Here the sifter 10 is not arranged within the sand chamber 2 but in a separate sifter chamber 16. The sifter chamber 16 is connected to the sand chamber 2 by way of a connecting passage 17 which narrows in the flow direction. The narrowing configuration of the connecting passage 17 provides that the flow speed of the air flow increases in the direction of the sifter chamber 16. The arrangement illustrated here forms at the end of the connecting portion 17 a sharp deflection so that a part of the sand, namely substantially the parts of the sand which cannot follow the air flow in the region of the sharp deflection by virtue of the inertia forces impinge against the wall 18 and are decelerated. Those sand particles then drop on to the bottom of the sifter chamber 16. The remaining air-sand flow is then passed through the sifter 10 which here rotates about a horizontal axis and by which sand portions whose diameter is larger than a limit grain size are also rejected. The particles which are smaller are drawn off by way of the air outlet 5. The particles collecting at the bottom of the sifter chamber 16 are conveyed back into the sand chamber 2 by means of the conveyor device 17 which here is in the form of a conveyor screw.

[0046] FIGS. 1 to 4 show embodiments in which casting sand cooling can be effected both continuously and also discontinuously. In the discontinuous case a given amount of casting sand is introduced into the sand chamber 2, the casting sand is then cooled and the casting sand is then completely removed by way of the casting sand outlet 8 so that in the following step it can be loaded with the next casting sand batch.

[0047] FIG. 5 shows a fifth embodiment in which casting sand cooling is effected continuously. Here, a fluidised bed 19 is arranged in the interior of the sand chamber 2 so that casting sand which is introduced by way of the casting sand inlet 7 is transported by way of the fluidised bed 19 gradually but continuously in the direction of the casting sand outlet 8. During such transport a large amount of air is fed into the sand chamber by way of the air inlet 3 and discharged by way of the air outlet 5. A dynamic sifter 10 is interposed.

[0048] FIG. 6 shows a sixth embodiment of the invention. The entire process of casting sand treatment can be explained on the basis of this embodiment. Used casting sand 20 is introduced into the sand chamber 2 by way of the casting sand inlet 7. The casting sand cooler here substantially corresponds to the embodiment of FIG. 1, in which respect however there is provided rotary speed regulation which in the manner according to the invention implements separation as between coarse and fine material. The casting sand to be cooled in the sand chamber is possibly mixed with water and then has a large amount of air flowing therethrough, the air being introduced into the sand chamber 2 by way of the air inlet 3. The air is passed by way of the dynamic sifter 10, by way of the connecting conduit 25 and by way of a filter 23 through the air outlet 5. The sifter 10 is set by means of the control device in such a way that sand components, that is to say particles of a size of greater than 100 m are rejected by the sifter. Smaller particles however are passed through by the sifter. These are essentially bentonite and carbon. They are filtered off in the filter 23 and passed into the weighing device 24. The amount of bentonite-carbon mixture which is separated off is measured in the weighing device 24 and possibly corrected by the addition of fresh bentonite 21 or carbon 22. As soon as the casting sand is cooled to the desired temperature of about 45 within the sand chamber 2 the sand can be transferred into the weighing device 27 by way of the casting sand outlet 8. Bentonite and carbon in the desired composition can then be fed to the weighing device 27 by way of the weighing device 24. Fresh sand 20 possibly also has to be supplied. The resulting mixture is then fed to a treatment mixer 28 and the proportion of water in the casting sand is possibly adapted by way of the water supply 29 in the treatment mixer 28.