EP0029133A1 - Process and apparatus for the production of a foundry mould - Google Patents

Abstract

A mold filling and compacting method includes forming a compact body of mold substance such as sand in an intermediate container and then abruptly opening the bottom closure of the container while releasing the sand, as a compact mass, so that it drops as a packet into the mold box, compacting itself effectively around a pattern arrangement. Specific techniques for releasing, including sudden lifting, sudden dropping and separating the container parts are disclosed as well as apparatus for performing the method.

Description

The present invention relates to a method for producing a foundry mold, in which a molding box is arranged on a model plate, molding sand is poured in from an intermediate container having a bottom closure.

From CH-PS 462 392 a method is known for dosing two types of molding sand in a molding box of a foundry mold using two sand silos with associated discharge devices and the intermediate container arranged below the latter, the bottom of which is formed by a shutter lock, in which by opening the shutter lock of the intermediate container, if this is brought into alignment with the molding box, the molding box is filled.

The process has the disadvantage that the molding sand is poured into the molding box practically uncompressed and, therefore, if a qualitatively perfect mold is to be produced, this is done in two compacting operations, e.g. in a first operation by shaking and in a subsequent operation by pressing or shaking presses.

From the magazine "LITJNOE PROIZVODSTVO in German" year gang 1962, page 38/39, an attempt to form compression by gravity and pressing is known. A mold with a height of 600 x 700 mm and a height of 250 mm is filled from a doser closed at the bottom by a slide with a sand filling of 500 mm height. The dispenser slides were opened quickly for filling. The test showed the greatest compaction in the lower layers of the sand filling, and no compaction in the upper layers. In addition, a smaller compression was found along the mold box walls, which also fell even more in the corners of the mold box. Experiments with larger forms have not become known; such tests would have given even worse results due to the longer time it took to open the metering slide. These results show that the method according to this test is not suitable for avoiding the known shortcomings in compacting a sand mold by pre-compacting when filling.

The object of the present invention is to avoid the above-mentioned disadvantages and to bring about a uniform and large compression of the sand filling in the molding box by optimally utilizing the potential energy of the sand in an intermediate container. Larger shapes should also be able to be produced.

According to the invention, this is achieved in that the molding material is suddenly released as a package from the intermediate container during the opening of the bottom closure. As a result, the time during which the impact force of the free-falling sand filling acts on the model or the model plate is significantly shortened, as a result of which the volume flow is considerably increased, with the result that the compression in the molding box takes place under the effect of an impact force. Tests showed that a uniform and large compression of the sand filling in the molding box was achieved.

A compression that already takes place in the intermediate container means that the molding material package becomes more compact and more resistant to breakup. This can e.g. done by means of a centrifugal roller or an arrangement according to CH-PS 301 031 can be used, in which pre-compression is brought about by a high column of molding sand.

The sudden release of the molding sand from the intermediate container is also achieved according to the invention in that the intermediate container either falls on stationary stops during the opening of the bottom closure or is suddenly raised from its rest position or in that the intermediate container is suddenly pulled off the molding sand in a multi-part design.

If the inside dimensions of the frame of the intermediate container are chosen to be smaller than the inside dimensions of the molding box, the compaction of the sand filling in the molding box is balanced and increased.

A subdivision of the intermediate container into several partial containers allows the production of large shapes.

Further inventive and / or advantageous designs and features can be found in the dependent claims.

Exemplary embodiments of the invention are shown in the drawings.

• Fig. 1 eine Ansicht einer Vorrichtung mit gefülltem Zwischenbehälter, teilweise geschnitten,
• Fig. 2 eine Ansicht der Vorrichtung nach Fig. 1 mit entleertem Zwischenbehälter, teilweise geschnitten,
• Fig. 3 eine Ansicht des Zwischenbehälters gemäss Pfeilrichtung A in Fig. 2,
• Fig. 4 eine Ansicht des Zwischenbehälters gemäss Pfeilrichtung B in Fig. 3,
• Fig. 4a eine Ansicht eines abgeänderten Zwischenbehälters gemäss Pfeilrichtung B in Fig. 3,
• Fig. 4b ein Detail einer Lamelle,
• Fig. 5 eine Ansicht eines weiteren Zwischenbehälters gemäss Pfeilrichtung C in Fig. 6, teilweise geschnitten gemäss Linie V - V,
• Fig. 6 eine Ansicht der Fig. 5 in Pfeilrichtung D,
• Fig. 7 einen Grundriss eines weiteren Zwischenbehälters,
• Fig. 8 eine Ansicht eines Zwischenbehälters gemäss Pfeilrichtung E in Fig. 7,
• Fig. 9 eine Ansicht einer Betätigungs-Vorrichtung gemäss Pfeilrichtung F in Fig. 7,
• Fig. 10 einen Schnitt gemäss Linie X - X in Fig. 9.

Show it:

• 1 is a view of a device with a filled intermediate container, partially in section,
• Fig. 2 is a view of the device of FIG. 1 with emptied intermediate container, partially cut,
• 3 shows a view of the intermediate container according to arrow direction A in FIG. 2,
• 4 shows a view of the intermediate container in the direction of arrow B in FIG. 3,
• 4a is a view of a modified intermediate container according to the direction of arrow B in Fig. 3,
• 4b shows a detail of a lamella,
• 5 shows a view of a further intermediate container according to arrow direction C in FIG. 6, partly in section according to line V - V,
• 6 is a view of FIG. 5 in the direction of arrow D,
• 7 is a plan view of a further intermediate container,
• 8 is a view of an intermediate container according to arrow direction E in FIG. 7,
• 9 is a view of an actuating device according to arrow direction F in Fig. 7,
• 10 shows a section along line X-X in FIG. 9.

In FIG. 1, 1 denotes a silo which is filled with molding material, for example molding sand 3 and has a discharge device 5 which cooperates with a centrifugal roller 7 during the sand discharge. An intermediate container 9, the bottom closure 19 and a frame arranged above it 31 (see also Fig. 2-4), is supported in a support structure 11, which is formed from two frames 13 and 15 and profiles 17. The bottom closure 19 of the intermediate container 9 consists of slats 21 which are rotatably mounted in the plates 23 which are connected to the frame 15 and can be actuated by the cylinders 25. The intermediate container 9 and the discharge device 5 can be displaced relative to one another.

2-4, the bottom closure 19 is shown in the open position 27 and in FIG. 1 in the closed position 29. The frame 31 is expediently flared downwards, since the sand filling 10 can then be separated most quickly from the wall of the intermediate container 9; it is supported in the raised position 33 via strips 34 on four rollers 35 of the lever 40. In the lowered position 37, however, the frame 31 is supported on the upper frame 13 via brackets 39. The support structure 11 with the intermediate container 9 is supported on rollers 41 on rails 43 and can be moved from the position 45 to the position 47 and back with the bottom closure 19 closed.

A model device 51, on which a molding box 53 is placed, is supported on a base 49. The inner dimensions 55 of the frame 31 of the intermediate container 9 are selected to be smaller than the inner dimensions 57 of the molding box 53. A vertically movable shaft 61 can be raised from a lowered position 63 by a cylinder 65 to a position 67 and is guided in a stationary shaft 59 . The dimensions 69 of the shaft 59 are chosen larger than the dimensions 57 of the molding box 53. The shaft 61 is guided through its upper part 71 in the shaft 59, while its lower part 73 is adapted to the dimensions 57 and through a conical central part 75 with the part 71 is connected. The centers of gravity 77, 79, 81 and 83 of the cross-sectional areas of the intermediate container 9, the shafts 59 and 61 and the molding box 53 are arranged on a common perpendicular 85. Adjustable guide plates can advantageously be installed in the shaft 61 so that the sand distribution in the molding box can be controlled.

• Die Fig. 1 zeigt den Zwischenbehälter 9 mit dem Bodenverschluss 19 in geschlossener Stellung 29 und mit einer Sandfüllung 10 in der Stellung 45 über der Modelleinrichtung 51. Die Modelleinrichtung 51 mit dem aufgesetzten Formkasten 53 stützt sich auf der Unterlage 49 ab. Der Schacht 61 ruht auf dem Ausleger 62 des Zylinders 65 in der angehobenen Stellung 67. Durch Betätigung des Zylinders 65 senkt sich der Ausleger 62 mit dem Schacht 61 in die Stellung 63 (siehe Fig. 2) und bildet dabei über dem Formkasten 53 mit dem Schacht 59 einen Abschluss über der Modelleinrichtung 51, der bis zum Zwischenbehälter 9 reicht. Durch Betätigung der Zylinder 25 wird über die Gestänge 26 der Bodenverschluss 19 aus der geschlossenen Stellung 29 in die geöffnete Stellung 27 bewegt. Gleichzeitig werden die Rollen 35 aus der Stellung 36 in die Stellung 38 bewegt und senken dabei den Rahmen 31 des Zwischenbehälters 9 aus der Stellung 33 in die Stellung 37, in welcher der Rahmen 31 schlagartig beim Aufsetzen der Konsolen 39 auf den Rahmen 13 der Tragkonstruktion 11 stillgesetzt wird. Durch die schlagartige Unterbrechung der Fallbewegung des Rahmens 31, löst sich die Sandfüllung 10 vom Rahmen 31 und setzt seine Fallbewegung in Pfeilrichtung 92 als geschlossenes Sandpaket 89 fort. Mit Vorteil wird die dem Sand zugekehrte Seite der Lamellen 21 mit einer haftreibungshemmenden Schicht beschichtet, beispielsweise mit "Teflon". Dadurch wird vermieden, dass die sich öffnenden Lamellen Sandpartien aus dem geschlossenen Sandpaket ausreissen. Auch die Innenwand des Zwischenbehälters 9 kann mit einer "Teflon"-Schicht ausgekleidet sein, damit der störende Faktor einer Haftreibung beim Lösen herabgesetzt wird.

The operation of the embodiment according to FIGS. 1-4 is described below:

• 1 shows the intermediate container 9 with the bottom closure 19 in the closed position 29 and with a sand filling 10 in the position 45 above the model device 51. The model device 51 with the molded box 53 is supported on the base 49. The shaft 61 rests on the arm 62 of the cylinder 65 in the raised position 67. By actuating the cylinder 65, the arm 62 with the shaft 61 lowers into the position 63 (see FIG. 2) and thereby forms over the molding box 53 with the Manhole 59 a closure over the model device 51, which extends to the intermediate container 9. By actuating the cylinder 25, the bottom lock 19 is moved from the closed position 29 to the open position 27 via the linkage 26. At the same time, the rollers 35 are moved from the position 36 to the position 38 and thereby lower the frame 31 of the intermediate container 9 from the position 33 to the position 37, in which the frame 31 abruptly when the brackets 39 are placed on the frame 13 of the supporting structure 11 is stopped. Due to the sudden interruption of the falling movement of the frame 31, the sand filling 10 detaches from the frame 31 and continues its falling movement in the direction of arrow 92 as a closed sand packet 89. The side of the slats 21 facing the sand is advantageously coated with an anti-static layer, for example with "Teflon". This prevents the opening slats from tearing out sections of sand from the closed sand package. Even the inside wall of the Intermediate container 9 can be lined with a "Teflon" layer so that the disruptive factor of static friction when loosening is reduced.

The closure formed by the shafts 59 and 61 above the molding box 53 has the effect that the entire sand filling 10 reaches the molding box 53 as a sand filling 58. Then, by reversing the cylinder 65, the boom 82 with the shaft 61 is raised to the position 67 and the model device 51 with the molding box 53 and the sand filling 58 is pushed off in a known manner and replaced by a next model device with a molding box attached. The opened bottom lock 19 is closed by reversing the cylinder 25 (position 29). While the intermediate container 9 moves at least once from the position 45 to the position 47 and back, the discharge device 5 conveys molding sand 3 from the silo 1 via a centrifugal roller 7 into the intermediate container 9 until the predetermined sand filling 10 is reached. A slide 2 which is movable in the height between two positions 4 and 6 enables sand fillings 10 of different sizes to be provided alternately.

Experiments have shown that the sand packet 89 is braked only insignificantly when passing through the vertical slats 21. Above all, the experiments show that dividing the sand packet 89 into several individual packets when passing through the slats 21 does not impermissibly reduce the compacting effect of the molding sand when it hits the model device 51, provided the thickness 22 of the slats 21 is not chosen too large and the upper one Edge is designed as a cutting edge (see Fig. 4b).

Experiments that were carried out on a device according to FIGS. 1-4 with a fall height 87 of 1.5 m resulted in a higher compaction of the sand filling 58 than that the one that is achieved by compacting by shaking. It is particularly surprising that the density of the sand filling 58 is very uniform and shows no reduction of importance up to the height 93. If necessary, it can be compacted again. This post-compression can occur mechanically or through an explosion or through a sudden expansion of gases.

If the inside dimensions 55 of the frame 31 are chosen to be smaller than the inside dimensions 57 of the molding box 53, not only can the air to be displaced escape more easily when the sand filling 10 is introduced into the molding box 53, but the experiments show that this also results in the sand filling 58 in the molding box 53 along the inside of the mold box 91 is compressed to the same degree as in the middle part of the mold.

FIG. 4a, which illustrates another embodiment of an intermediate container, is described below to the extent that it differs from the embodiment shown in FIGS. 1-4. The piston rods 96 of the vertical cylinders 95 arranged on both sides are in the position 97 and hold the bottom lock 19 in the open position 27 via the linkage 26 , carry the frame 31 in the raised position 107 via brackets 105. If the cylinder 95 is reversed, the piston rod 96 moves from the position 97 to the position 109 and closes the base lock 19 (position 29). At the same time, the levers 99 are moved from the position 111 to the position 113, whereby the frame 31 is lowered from the position 107 to the position 115, in which the frame 31 is supported on the upper frame 13 via the brackets 105.

• Ist der Zwischenbehälter 9 mit einer Sandfüllung 10 in der Stellung 45 und der Bodenverschluss 19 in der geschlossenen Stellung 29, so befindet sich der Rahmen 31 in der abgesenkten Stellung 115. Die Kunststoffrohre 103 sind um die Distanz 117 von der Konsole 105 abstehend und entlastet. Wird der Bodenverschluss 19 durch Umsteuerung der Zylinder 95 geöffnet, indem sich die Kolbenstangen 96 von der Stellung 109 in die Stellung 97 bewegen, so bewegen sich auch die Hebel 99 aus der Stellung 113 in die Stellung 111 und heben die Hubstangen 101 und die Kunststoffrohre 103 an. Erst nachdem die Kunststoffrohre 103, die bei Belastung elastisch deformieren, um die Distanz 117 angehoben sind, hebt sich schlagartig auch der Rahmen 31 aus der Stellung 115 in die Stellung 107 an und löst dadurch die Sandfüllung 10 (siehe Fig. 1) aus dem Zwischenbehälter 9.

4a works as follows:

• If the intermediate container 9 with a sand filling 10 in the position 45 and the bottom closure 19 in the closed position 29, the frame 31 is in the lowered position 115. The plastic tubes 103 protrude and are relieved from the bracket 105 by the distance 117. If the bottom lock 19 is opened by reversing the cylinder 95 by moving the piston rods 96 from the position 109 to the position 97, the levers 99 also move from the position 113 to the position 111 and lift the lifting rods 101 and the plastic tubes 103 at. Only after the plastic pipes 103, which deform elastically under load, are raised by the distance 117, does the frame 31 suddenly rise from the position 115 to the position 107 and thereby detach the sand filling 10 (see FIG. 1) from the intermediate container 9.

While the embodiment according to FIG. 4 suddenly releases the sand filling 10 at the beginning of the opening process of the bottom closure 19, in the embodiment according to FIG. 4 a the time of the sudden release of the sand filling 10 from the intermediate container 9 can be selected at any time during the opening process. The choice of the point in time is made possible by changing the distance 117 or the length of the plastic tube 103.

5 and 6 show a device which enables the method according to the invention to be used for particularly large shapes. The device according to FIGS. 5 and 6 differs from the devices according to FIGS. 1-4 and 4a in that the intermediate container 9 is divided into four different partial containers 9a to 9d by the intermediate walls 119. As a result, the length 121 of the slats 21a to 21d and thus the slat thickness 22 can be within one for the passage of the sand packet 98 through the slats 21 permissible thicknesses can be selected.

The design of the discharge device 5a and the centrifugal roller 7a according to FIGS. 5 and 6 corresponds, apart from the larger width 123, to the embodiment according to FIG. 1.

The intermediate container 9 with the bottom closure 19 is supported on a supporting structure 11, which is formed from an upper and a lower frame 13 and 15 and profiles 17. The support structure 11 is additionally braced by narrow supports 125, which simultaneously serve as a support structure for the intermediate bearings 127 of the individual lamellae 21a to 21d.

The frame 31 is divided into four partial spaces 131 by three additional double partitions 129. The double partitions 129 reach over the supports 125 on both sides and can be raised and lowered simultaneously with the frame 31 with which they are firmly connected. The bottom lock 19, the sudden raising and lowering of the frame 31, is actuated in the same way as described for FIG. 4a in that the devices 95, 96, 26, 99, 101 provided for this on both sides of the frame 31 in FIG. 4a , 103, 105 are also provided within the double partitions 129.

The embodiment shown in FIGS. 7 to 10 differs fundamentally from the embodiments according to FIGS. 1-5. While the frame 31 in FIGS. 1-6 is made in one piece and can only be moved vertically, the embodiment according to FIGS 7-10, a two-part frame 133 is provided, which is divided in diagonal 135 into frame halves 133a and 133b, which can suddenly be pulled away from the sand filling 136 and pushed together again. Support the frame halves 133a and 133b thereby on tabs 134a and 134b on the support structure 144. In order to release the sand filling 136 from the frame 133 of the intermediate container 139, cylinders 141 with piston rods 143 and parts 145 which can be lifted and lowered are provided in the divided corners 137 and 139. The cylinders 141 are fixed to the lower frame 142 of the support structure 144. Each of the parts 147 and 149 connected to the frame halves 133a and 133b each has a cam 151 and 153 which engage in the grooves 155 and 157 of the parts 145.

9 and 10 show the frame halves 133a and 133b in the closed position 159 on the diagonal 135. If the parts 145 are lifted from the position 161 to the position 163 by reversing the cylinder 141, then after passing through a certain partial stroke, because the cams 151 and 153 are guided with play in the grooves 155 and 157, the frame halves 133a and 133b are suddenly moved into the positions 165 and 167 or removed from the sand filling 136. Since the frame halves 133a and 133b are suddenly pushed apart, the sand filling 136 falls as a closed sand package 89 (FIG. 2) from the intermediate container 138 formed by the bottom closure 19 and the frame halves 133a and 133b. The parts 145 become out of position by reversing the cylinder 141 Position 163 lowered again to position 161, the frame halves 133a and 133b are moved back into the closed position 129.

Claims (13)

l. A method for producing a foundry mold, in which a molding box is arranged on a model plate, molding sand is poured in from an intermediate container having a bottom closure, characterized in that the molding material is suddenly released as a package from the intermediate container during the opening of the bottom closure. 2. The method according to claim 1, characterized in that the molding material is introduced into the intermediate container such that a pre-compression takes place in the intermediate container. 3. The method according to claim 1 or 2, characterized in that the intermediate container falls on stationary stops during the opening of the bottom closure. 4. The method according to claim 1 or 2, characterized in that the intermediate container is suddenly raised from a rest position during the opening of the bottom closure. 5. The method according to claim 1 or 2, characterized in that a multi-part intermediate container is suddenly withdrawn from the molding sand. 6. Molding machine for performing the method according to An Claim 1, which has a model device (51) on which a molding box (53) can be placed, which also has a molding material silo (1) with a discharge device (5) above an intermediate container (9) with a bottom closure (19), which has one Drive for opening and closing, characterized in that the intermediate container (9, 138) has a bottom closure (19) and a frame (31, 133) which can be moved independently thereof, and that drive means (25, 95, 141) are provided with which the position of the frame (31, 133) can be changed suddenly during the opening of the base lock (19). 7. Molding machine according to claim 6, characterized in that from the bottom lock (19) actuated lever (40) and rollers (35) are provided, with which the frame (31) of the intermediate container (9) when closing the bottom lock (19) of the Support structure (11) can be lifted off and can be dropped onto the support structure (11) when opening the bottom lock (19). (Fig. 1 - 4) 8. Molding machine according to claim 6, characterized in that levers (99), lifting rods (101) and elastically deformable tubes (103) are provided, whereby the frame (31) of the intermediate container (9) via brackets (105) when opening the bottom closure (19) can be raised suddenly. (Fig. 4a) 9. Molding machine according to claim 6, characterized in that the frame (133) of the intermediate container (138) is divided in the diagonal (135) and consists of two halves (133a and 133b) which have cams (151, 153) on both sides, which are guided with play in grooves (155, 157) of a liftable and lowerable part (145), the part (145) abruptly lifting the two halves when raised (133a and 133b) can be pushed apart. (Fig. 7-10) 10. Molding machine according to one or more of claims 6 to 9, characterized in that the internal dimensions (55) of the frame (31, 138) are smaller than the internal dimensions (57) of the molding box (53). 11. Molding machine according to one or more of claims 6 to 10, characterized in that the intermediate container (9) is divided into several partial containers (9a-9d), the supporting structure (11) being additionally stiffened by narrow supports (125) , The intermediate bearings (127) of the slats (2la - 21d) serve as a suspension and that double partitions (129) are provided, which extend over the supports (125) on both sides and are firmly connected to the frame (31) so that they can be raised and lowered. (Fig. 5, 6) 12. Molding machine according to claim 6, characterized in that the edges (24) of the lamellae (21a-21d) opposing the sand flow are designed as a cutting edge. (Fig. 4b) 13. Molding machine according to one of claims 6 to 12, characterized in that the inner wall and / or the bottom (21) of the intermediate container (9) is lined with an anti-static layer.

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