WO2009043838A1

WO2009043838A1 - Selection of a used sand stream occurring after casting production and device therefor

Info

Publication number: WO2009043838A1
Application number: PCT/EP2008/063040
Authority: WO
Inventors: Frank Iburg
Original assignee: Kuenkel-Wagner Prozesstechnologie Gmbh
Priority date: 2007-09-29
Filing date: 2008-09-29
Publication date: 2009-04-09
Also published as: CN101848778B; EP2192999A1; CN101848778A; BRPI0817613A2; DE102007046779A1

Abstract

The invention relates to a device for selecting highly thermally stressed used sand having a high core sand fraction of lightly thermally stressed used sand of a total used sand stream occurring after the demolding of cast parts. A screen drum (2), which can be driven to rotate around a horizontal axis, having an entry end (4) is provided for supplying the used sand stream (9). An exit end (5) for a removal of sand lumps, which have not completely disintegrated upon passage of the screen drum, is also provided. A bunker-like collection housing (11), the length and the width of which at least correspond to the width and the length of the screen drum (2), is arranged below the rotating drum. At least one partition wall element (13) oriented transversely and perpendicularly to the axis of rotation (3) of the screen drum (2) is arranged in the housing (11). Said wall element divides the interior chamber of the collection housing (11) - in relation to the length of the screen drum (9) - into at least two sections (20, 21), the widths and relative positions of which are each adjusted to a defined longitudinal section (A, B) of the screen drum. In the lower area of each of the sections, an (independent) device (16, 17) is arranged for removing the quantity of screened-out used sand collected in the respective section.

Description

SELECTING AN ALTERNATE CURRENT AFTER CAST MANUFACTURE AND

DEVICE FOR THIS

Casting in clay-bonded sand molds often uses numerous sand cores for certain castings, such as engine blocks, cylinder heads, pump housings, and others. In the after pouring and unpacking of castings accumulating Altsandstrom the cores remain mostly as sand tubers, but also as spent, free-flowing single grains. The used sand is reprocessed into the molding material.

For the reprocessing, it is a problem that the total amount of used sand is constantly increasing due to the core sand feed and that parts of the used sand have to be disposed of or regenerated. The core-intensive casting production results in significantly higher processing costs as well as negative technological influences on the molding material quality. For example, the sand treatment of clay-bound used sand, which is "diluted" with high core sand feed, is associated with significantly higher additive consumption On the other hand, the regeneration of mixed residual sand with a high proportion of fresh clay is technologically difficult and energetically much less favorable than the regeneration of pure core salt and thermally stressed clay-bound used sand.

In DE-A 10 2005 055 877 it has been proposed to reduce the core sand feed and the proportion of thermally stressed old sand by selectively unpacking the mold, wherein the casting and the molding material are unpacked separately from the molding box.

It is an object of the invention to select the Kernsandzulauf and the proportion of thermally stressed portions in the resulting Altsandstrom in a simple and cost-saving manner and effectively separate from the less heavily thermally stressed used sand in the resulting Altsandstrom without great mechanical effort.

This object is achieved according to the present invention by the device according to claim 1 and the method according to claim 7. Likewise claim 10 or claim 22.

The separation of the different proportions of sand in the resulting Altsandstrom within a rotationally driven about a horizontal axis screen drum, at the inlet end of the resulting used Altsandstrom and further promoted by the rotation of the drum in the direction of the discharge end of the drum at a moderate pace. The separated and exiting through the screen wall of the drum sand grains are received by a flush arranged below the screen drum bunker-like housing - corresponding to the dimensions of the screen drum - width and length dimensions and arranged in accordance with the selected in the screen drum Altsandanteilen and separate housing sections, which each own devices, such as conveyor belts or the like., Are assigned for the removal of selected Altsandbestandteile.

The device according to the invention thus consists essentially only of two simple components: the rotating screen drum and the bunker-like collecting housing adapted to this, which are separated from one another in at least two

Housing sections is divided. The amount of equipment and mechanics is low.

The selection is continuous and automatic. The location (s) in the collection housing, where it is subdivided into separate sections, are exactly adjusted to the screening process that takes place in the sieve drum.

This is based on the exact observation on which initial length of the screen drum when the old sand stream enters the unbound core sand single grains and the individual grains of the thermally heavily used used sand fraction spontaneously through the

Screen wall of the drum trickle. The 'width' - measured in the longitudinal direction of the drum - the first section of the bunker-like collecting housing is tuned to this initial length of the screening drum. The moist, thermally predominantly less stressed used sand is conveyed beyond the initial length of the screen drum and thereby or subsequently sieved, wherein the screening process is made possible in part only by the action of centrifugal forces. Thus, the less used used sand predominantly enters the second section or, if appropriate, further provided sections of the collecting housing.

The invention will be described in more detail below with reference to schematic drawings of several exemplary embodiments:

FIG. 1 shows the device in a vertical section in a side view, FIG. 2 shows the screening device as seen in the direction of the entry end of the screening drum,

3, 4 alternative embodiment (claim 10),

Figure 3a, 3b shows a device for selecting sand in two 90 ° views. The polygon screen can be seen at the top and the partition element in FIG. 3b at 79 '.

The screening device 1 comprises a horizontally arranged screening drum 2, the horizontal axis 3 of which is mounted in a housing enclosing the sieve drum 7, which is open at the bottom. The inlet end 4 of the screening drum 2 serves to supply the waste sand stream obtained after completion of the casting and demolding operation of the cast parts, which is indicated in FIG. 1 only by the arrow 9. For feeding the used sand stream, e.g. a funnel 9a serve. The opposite outlet end 5 of the screening drum 2 is used for discharging during the passage of the drum also by the friction occurring and the existing centrifugal forces not in individual grains dissected sand lumps or dumplings, as indicated by the arrow 10.

The screen drum 2 is formed polygonal in the illustrated preferred embodiment, as best seen in Figure 2 can be seen. In addition, it is preferred, as shown, in the longitudinal direction from the inlet end 4 to the outlet end 5 conically weakly widened, as can be seen from Figure 1. As a result, a promotion of the sand located in the screen drum 2 from the inlet end 4 in the direction of the outlet end 5 is ensured with a favorable for the screening process and especially for the desired selection conveyor speed. The extension of the screening drum 2 can be done gradually, but preferably steadily. The diameter enlargement also has the advantage that the friction and the action of centrifugal forces on the sand flow, which promote the singulation and screening of the sand grains, increase towards the rear area of the drum.

The jacket of the screening drum is supported on the drum shaft 3 by radial struts 6. The drum shaft 6 is driven by a drive device 8 near the

Exit end 5 constantly set in rotation. The separated and falling down through the screen wall of the screen drum 2 sand grains fall into a bunker-like collecting housing 11 arranged below the screen drum, whose width and length correspond to the width and length of the screen drum 2. The upper edge 12 of the housing 11 is located only slightly below the bottom of the screening device 1. The front wall is indicated at 12a and the rear wall at 12b.

Of importance for the function is the exact observation of the respective behavior of the different core sand and Altsandanteile the Altsandstromes in the screening drum during the sieving process. Thus, it should be noted that a large part of the grains of sand of the unbonded core sand grains and the individual grains of the more thermally stressed used sand portion trickle when entering the Altsandstromes in the inlet end 4 of the screen drum 2 immediately through the screen wall of the screen drum. They thus arrive in the front region of the collecting housing 11 adjoining the wall 12a. It turns out that this rapid screening of the individual granules on a limited initial length - A in FIG. 1 - happens to the screening drum 2. In one of these initial length A corresponding distance from the front wall 12a of the collecting housing 11 is arranged in this one transverse to the shaft 3 and below the screen drum, a partition wall 13, whereby a first section 20 is formed, in which the screened in section A single grains are collected. Behind the partition wall 13, a second section 21 of the collecting housing is formed by the latter, in which the individual sand grains which have been sifted out in the remaining section B of the screening drum are collected. These belong to the moister, less thermally stressed used sand, due to the rotational movement of the sieve drum in the

Drum section B is promoted while the friction and centrifugal forces is exposed, which promotes the grain separation and the screening process.

The partition wall 13 in the collecting housing 11 begins at the top with a separating edge 14 and has in the lower region 15 two in opposite directions inclined guide elements 15a and 15b, which the groupage from each section 20 and 21 on a down in the section arranged discharge device, such as Derive conveyor belt 16 or 17.

With 23a and 23b possible filling heights in the two sections are indicated. The outlet of the sifted grains of sand is indicated at 25 in FIG.

By the processes described above, the desired selection of Kernsandeinzelkörner and the individual grains of the more thermally stressed Altsandanteils on the one hand by the moister and thermally weaker used used sand on the other hand ensured in a simple manner. It is only necessary to supply the resulting after demolding total Altsandstrom the inlet end of the rotating screen drum 2 and the same in the front section A of the length of the screen drum ausrieselnden single sand grains in a corresponding to arrange arranged and separated portion 20 of the collecting housing. The single grains flowing out in the further inward (or rearward) section B of the screening drum 2 are collected in a further, separated section of the collecting housing. The respective amounts of sand collected separately from the collecting housing 11 to dissipate.

For this simple procedure, only a correspondingly simple and inexpensive device is required to 'ensure' the selection without much effort and master the problems mentioned above.

Claims

Claims:

1. Apparatus for selecting thermally stressed used sand with

5 high core sand content of thermally low used used sand of a - after demolding of castings - accumulating total used sand, consisting of a rotating about a horizontal axis screen drum (2) having an inlet end (4) for supplying the used sand stream (9) and an outlet end ( 5) for a discharge of - when passing the lo sieve drum not completely disintegrated - tubers or the like., And from a small distance below the rotatable drum arranged bunker-like collecting housing (1 1), the width and the length of at least the width and the Length of the screen drum (2) corresponds, wherein in the housing (1 1) at least one, transverse and perpendicular to the rotation axis (3) of the screen drum (2) oriented partition member (13) is arranged, which the interior of the

Collection housing (1 1) - based on the length of the screen drum (9) - divided into at least two sections (20,21) whose width and relative position are each tuned to a particular length section (A ₁ B) of the screen drum, wherein in the lower Area of each of the sections one (stand-alone)

20 device (16,17) for conveying the collected in the respective section

Amount of screened used sand is arranged.

2. Device according to claim 1, wherein the position and width of each section (20,21) of the collecting housing (11) - based on the screening drum (2) - in dependence of

25 the different specific screening behavior of the different

Components of introduced into the sieve drum (4) Altsandstroms (9) are determined.

3. A device according to claim 2, wherein the width of each section (20,21) of the collecting housing (11) is at least 100 mm.

4. Apparatus according to claim 1 or 2, wherein the or each partition wall element (13) above a separating edge (14) and below two inclined by the wall in opposite directions Ableitschrägen (15a, 15b) for discharging

35 of the in the by the partition wall element (13) separate sections (20,21) collected sand portions on the section of the associated discharge device (16,17).

5. Device according to one of the preceding claims, wherein the screen wall of the screen drum (2) has a polygonal cross section.

6. Device according to one of the preceding claims, wherein the diameter of the screen drum (2) from the inlet end (4) to the outlet end (5) out, preferably steadily, increases, and in particular in the scope, for a promotion with on the screening process coordinated conveying speed of the used in the screen drum (2) old sand amount in the direction of the outlet end (5) is required.

10

7. A method for selecting thermally highly stressed used sand with high core sand content of thermally low-stressed used sand of the demolding of castings accumulating total Altsandstrom supplied to the inlet end of a polygonal, about a horizontal axis continuously rotating i5 sieve drum (2) and by the rotational movement the drum in

Direction to the other end of the screen drum is passed, while the sifted on the way through the screen drum sand grains depending on in which longitudinal section (A ₁ B) of the screen drum they trickle through the screen wall, each separately in a longitudinal section associated portion (20, 21)

20 of a bunker-like collecting housing (11) arranged under the sieve drum are collected and discharged separately therefrom.

8. The method of claim 7, wherein the at entry (4) of the Altsandstromes in the screen drum (2) rapidly through the screen wall of the drum trickling single grains

25 of the nodular core sand particles and the more thermally stressed

Altsandanteil be collected in a the front longitudinal section of the screen drum associated portion of the collecting housing and thus selected from the moister and less thermally stressed portions of used sand.

30

9. The method of claim 8, wherein the moister and less thermally stressed Altsandanteile further promoted by the rotation of the screen drum (2) towards the outlet end (5) of the drum and under the effect of acting on the used sand friction and - possibly reinforced -

35 centrifugal forces further away from the entrance end of the screen drum

Sections of the drum are divided into individual grains and screened and collected in one or more separated further sections of the collection and removed separately therefrom.

10. A method for treating a mixture of differently stressed molding material (44), with a first portion of thermally stressed molding material and a second portion of thermally less stressed molding sand,

5 wherein the mixture (44)

(a) being introduced into a rotating polygon screen (50) having external screen surfaces (55) rotating at a peripheral speed;

(B) during the rotation of the Polygonsiebs (50), the mixture (44) in the longitudinal direction (100) of the Polygon screen is moved, and locally concentrated according to the differently thermally stressed portions, wherein

(1) the heavier loaded portion is concentrated closer to the starting portion (52a) of the polygon screen (50) and screened out here by the screen surfaces (55);

(2) the less stressed portion is concentrated closer to the end portion (52b) and screened out here by the screen surfaces (55);

(c) conveying the separated two portions separately (81, 82).

20

The method of claim 10, wherein the initial region (52a) is shorter than the end region (52b), more preferably less than half as long, for example, occupying substantially one-third to one-fourth of an overall length of the polygon screen (50).

25

12. The method of claim 10, wherein behind the end portion (52b) of the Polygonsiebs third portions of the molding material mixture (44) from the Polygonsieb (50) axially emerge, which have Überkerngröße, in particular - by rubbing and conveying in the polygon screen - not or not sufficient

30 crushed tubers (44k).

13. The method of claim 10, wherein the thermally highly stressed portion (44t) core sand and the less thermally stressed portion

Molding sand (44f) is the latter, which has a greater moisture content.

35

14. The method of claim 10, wherein a centrifugal force on the molding material mixture (44) increases during the rotation of the Polygonsiebs to the end (E).

A method according to claim 10, wherein the two screened portions (44t, 44f) are kept and guided separately by a screen (78, 79; 70a, 70b) after screening and before conveying.

16. The method according to claim 10 or 15, wherein a first, transverse to

Inclined longitudinal direction (100) of the polygon screen (50) oriented wall surface (70b), and the first portion (44t) a first conveyor (81) zuleitet.

17. The method of claim 15 or 16, wherein a second inclined wall surface (70a) is aligned transversely to the longitudinal direction (100) of the Polygon screen and the second portion (44f) a second conveyor (82) zuleitet.

18. The method of claim 17, wherein the inclination of the first inclined wall surface and the inclination of the second inclined wall surface are in opposite directions.

19. The method of claim 17, wherein the two inclined wall surfaces (70a, 70b) have a common separating edge (78), with which the two portions of the molding material mixture are kept separate and fed from the inclined wall surfaces each to another conveyor belt (81, 82) become.

20. The method of claim 16 or 17, wherein the inclined first or second wall surface (70a, 70b) in a vertical wall (79) over which extends closer to the rotating polygon screen (50) and at its upper end a separating edge (78).

21. Method according to claim 16, wherein the first or second wall surface (70a, 70b) has a free edge (78) pointing towards the polygon screen (50) for separating or holding separately the squeezed shaped material portions subjected to different loads.

22. separating and guiding device for mixed used sand from core and molding sand, for carrying out the method according to any one of the preceding claims, wherein a screen drum (50) with outer screen surfaces (55) is rotatably supported above a bunker or guide device (75) .

5 - the screen surfaces (55a, 55b, 55c ...) a polyhedral, three-dimensional

Form body of the sieve drum (50); a bunker or guide device (75) is arranged below the sieve drum (50) and has at least two separate conveyors (81, 82) underneath it; lo - in the guide device (75) at least one, preferably two oppositely inclined wall surface (s) (70a, 70b) are arranged separately to thermally stronger and thermally less heavily used used sand the separate conveyors (81, 82); the at least one inclined wall surface (70a, 70b) has a separating edge (78) oriented towards the screen drum (50) and oriented transversely to its longitudinal direction (100).

23. separating and guiding device according to claim 22, wherein the separating edge (78) is adjustable in height, in particular on one and with a wall surface.

20

24. Device according to one of claims 1 to 6, wherein an inclination of screen surfaces of the screen drum (2) from the inlet end (4) to the outlet end (5) is more than 2 °; and / or the speed of the drum is above 15 U / min.

25

25. The method according to claim 10 or 13, wherein the thermally highly stressed portion (44t) has used sand with spent binder casings, and the less thermally stressed portion is molding sand (44f) having a greater moisture content.

30