Method and apparatus for producing foundry molds

Abstract

 A molding apparatus for producing foundry molds by means of molding boxes and pattern plates includes: a station for filling with molding sand one empty molding box (3) at a time, the molding box being associated with a respective pattern plate; a station for packing or molding the filled molding boxes; a carousel for supporting, two pattern plates and a single molding box at a time, at the diametrically opposite ends. An input line (2) for the entry of empty molding boxes into the filling station and an output line (5) for the exit of the molded molding boxes from the molding station, the lines (2, 5) being separate and substantially parallel. In the working cycle of the apparatus, the empty molding boxes enter the filling station along the input line and exit after molding from the molding station to advance directly along the output line.

Description

[0001] The present invention relates to a method and an apparatus for producing foundry molds.

[0002] More particularly, the present invention is used in the field of foundry and relates to an apparatus for producing green-sand molds by using molding boxes and pattern plates.

[0003] The apparatus according to the invention is of the type including: a molding-sand filling station for loading empty molding boxes associated with a pattern plate; a molding station for packing the filled molding boxes; a carousel which can rotate about a substantially vertical axis and is suitable to support, at its diametrically opposite ends, two pattern plates which can be coupled to respective molding boxes; and a rotation means which acts on the carousel in order to rotate it through 180° at a time in both directions.

[0004] The invention also relates to a method for producing foundry molds by means of the above apparatus.

[0005] DE-C-2 220 276 discloses a machine and a plant, for producing foundry molds, including a rotating carousel for transferring the molding boxes between a station for loading and packing the sand and a station for mold extraction and molding box release. This conventional machine has the drawback that it is very complex and slow due to the fact that the entry and the exit of the molding boxes occur in a same station, where it is necessary to stop each molding box for a relatively long time.

[0006] EP-A-327825 discloses a molding machine of the type that includes a carousel which can rotate about a vertical axis through 180° in both directions, with two diametrically opposite arms for moving the molding boxes between a filling station and a packing station which are diametrically mutually opposite. A pattern plate, respectively for an upper half-mold and for a lower half-mold, and for the respective molding boxes, is placed on each arm. While one molding box is arranged together with a pattern plate in the filling station, the other molding box is placed, together with the other plate, in the sand packing station.

[0007] A drawback of this conventional machine is the slowness of the molding box molding cycle, due to the fact that in each cycle a molding box, together with the respective pattern plate, must be removed from the feeder line, then transferred to the filling station to be filled with sand, and then returned into the packing station to be molded and transferred to the casting area. In this way, both during transfer to the filling station and during return to the molding station the pattern plate is stably coupled to a respective molding box. From a structural point of view, the line for feeding the empty molding boxes and the line for feeding the molded molding boxes are an extension of one another, as shown in the schematic diagram of FIG. 1. This arrangement and this operating method create a delay in the advancement of the train of molding boxes, considerably extending the time required to perform each cycle, so that a capacity of more than approximately 200 molding operations per hour is not possible.

[0008] Accordingly, in order to feed plants having a higher capacity it is necessary to provide two machines provided with respective incoming and outgoing molding-box feed lines, with an evident increase in plant and production costs.

[0009] The aim of the present invention is to overcome the above drawbacks, providing a method and a molding apparatus which allow a reduced number of steps and a consequent reduction in molding times and costs.

[0010] A particular object of the invention is to provide a method and a molding apparatus which are faster in performing the molding cycle.

[0011] A further object is to minimize the movements of the molding boxes associated with the pattern plates.

[0012] This aim, these objects and others which will become apparent hereinafter are achieved by a molding method as defined in claim 1 and by a molding apparatus as defined in claim 6.

[0013] The dependent claims disclose specific and particularly advantageous embodiments of the method and of the apparatus according to the invention.

[0014] The advantages of a method and an apparatus according to the invention are as follows.

[0015] In the working cycle, each molding box is associated with a respective pattern plate and immediately enters the filling station without passing through the molding station. After packing the sand, the molded molding box leaves the molding station immediately and only the pattern plate returns to the filling station to be associated with an empty molding box.

[0016] The apparatus has a line for the entry of the empty molding boxes which is distinct and parallel with respect to the line for the exit of the molded molding boxes, eliminating the need for a back-and-forth movement of the molding boxes and making it sufficient to transfer the molding boxes from one line to the other in order to perform the filling and molding step.

[0017] Further characteristics and advantages of the invention will become apparent from the detailed description of a preferred but not exclusive embodiment of an apparatus and a method according to the invention, described by way of non-limitative example with the aid of the accompanying drawings, wherein:

FIG. 1 is a view of a layout of an apparatus according to the prior art;

FIG. 2 is a view of a layout of an apparatus according to the invention;

FIG. 3 is an enlarged front view of a molding apparatus according to the invention, taken along the plane III-III of FIG. 2;

FIG. 4 is a plan view of the apparatus of FIG. 3;

FIG.s 5a to 5f are reduced side views of the apparatus of FIG. 3 in successive steps of the molding cycle.

[0018] With particular reference to FIG. 2, a molding apparatus according to the invention, generally designated by the reference numeral 1, can be included in a plant for the continuous production of foundry molds by means of molding boxes and pattern plates.

[0019] The apparatus, which has a supporting structure 1' with a central axis V that passes through the longitudinal center line M, is fed upstream by an input line 2 for conveying empty molding boxes 3''. Input line 2 is, for example, constituted by fixed guiding roller conveyors 4 which run in a first direction L which is substantially parallel to the center line M, and unload the molded molding boxes 3 in a downstream region onto a conveyance line 5 which is separate from the first line and is also constituted by fixed guiding roller conveyors 6 which run in a direction L' which is parallel to the first one.

[0020] With particular reference to FIG.s 3 and 4, the apparatus 1 includes a supporting structure 7 which is anchored to the ground and supports a filling station 8, at one end, and a molding-box molding station 9, at the opposite end.

[0021] Filling station 8 includes a hopper 10 for loading sand in a controlled amount by means of a dosage chamber 10' of a per se known type.

[0022] The molding station 9 includes a packing head 11, for example an impact packing head with injection valve, as disclosed in EP-A-0781613, in the name of this same Applicant.

[0023] Before entering the filling station 8, each empty molding box is first covered by a filling frame 12 which arrives from the molding box 3 packed in the molding station 9, by means of a suitable transfer means described in greater detail hereinafter. The frame 12 is adapted to facilitate the loading of the sand and the packing of the molding box.

[0024] A carousel 13 is mounted on the supporting structure 7 and is anchored to a column 14 which can rotate about the vertical axis V that lies along the center line M of apparatus 1. An actuation mechanism 15, based on hydraulic or pneumatic cylinders, acts on the carousel 13 so as to allow it to turn through 180° in both directions.

[0025] The dimensions of the carousel 13 are such that, at its two diametrically opposite ends, the carousel supports respective pattern plates 16, 16', at the two stations 8 and 9.

[0026] A filling table 17, which supports the pattern plate 16, is arranged below the carousel 13, at the filling station 8. The table 17 is actuated by an actuator 18 so as to place the pattern plate 16 in contact with an empty molding box 3 and with a respective filling frame 12. By continuing the lifting motion of the table 17, the pack constituted by the plate 16, by the molding box 3 and the filling frame 12 can be moved toward the mouth of the loading hopper 10 to facilitate the filling of sand.

[0027] A loading roller conveyor 19 is arranged on the filling table 17 in order to allow to easily load and unload the plate 16 from the table 17, when changing pattern.

[0028] Likewise, a molding table 20, which supports the pattern plate 16' together with the filled molding box 3', is arranged below the carousel 13 at the molding station 9. Table 20 is actuated by actuators 21 which are adapted to move the plate 16' into contact with the filled molding box 3' and with the filling frame 12'.

[0029] A pair of movable roller conveyors 22 are provided in the filling station 8, and can be moved selectively mutually closer, transversely to the direction L of the line 2, in order to allow the empty molding boxes to entry, or can be moved far apart in order to allow the movable table 17 to lift each molding box 3. Likewise, a second pair of movable roller conveyors 23 are provided in the molding station 9 and can be moved mutually closer, transversely to the line 5, in order to align with the fixed roller conveyors 6, or can be moved mutually apart to allow the molding box 3' and the filling frame 12' to lift the pack formed by the pattern plate 16', in order to move it toward the packing head 11 of the molding station 9.

[0030] A collet-type transfer device, generally designated by the reference numeral 24, is provided to remove the frame 12' that is superimposed on the molded molding box 3', to transfer the frame 12' initially in the longitudinal direction F and then in the transverse direction T, until It is superimposed on an empty molding box 3'' entering the filling station 8.

[0031] The operating method of the apparatus 1 is shown step by step in FIG.s 5a to 5f and is characterized in that the empty molding boxes enter, one at a time, the filling station 8 along the input line 2 and exit after molding in the packing station 9 in order to advance directly along the output line 5.

[0032] As shown in FIG. 5a, initially, a filling frame 12 is superimposed on an empty molding box 3'' which has not yet entered the filling station, while a molding box 3, which is already filled and coupled to a frame 12, is about to be transferred into the molding station 9. Simultaneously, a molded molding box 3' is unloaded in the molding station 9 onto the output line 5 and moves away from the apparatus.

[0033] FIG. 5b is a view of the subsequent step, during which the carousel 13 has been rotated through 180°; accordingly, the filled molding box 3' has been moved into the molding station 9, while only the pattern plate 16' returns to the filling station 8. Simultaneously, the empty molding box 3'' has entered the filling station 6 to be coupled to the frame 12'', while the filled molding box 3 lies below the packing head 11 so that the pattern plate 16 is superimposed on the table 17'.

[0034] In the subsequent step, shown in FIG. 5c, the table 17 is lifted by the cylinder 18, placing the pattern plate 17' in contact with the molding box 3'', while, in the molding station, table 17' is lifted by the actuators 21 after moving the movable roller conveyors 23 mutually apart, placing the pack formed by the molding box 3 and by the frame 12 against the packing head 11.

[0035] FIG. 5d shows that in the filling station 8 the molding box 3'' is full while in the molding station 9 the molding box 3 is subjected to the injection performed by the head 11 and to the consequent packing of the sand.

[0036] FIG. 5e shows that in the filling station 8 the molding box 3'' has been filled and lowered after the movable roller conveyors 23 have been moved mutually apart. Simultaneously, in the molding station 9 the table 17' is lowered, moving the pattern plate 16 away from the molded molding box 3. During this step, the movable roller conveyors 23 are mutually closer, supporting the molding box 3 and separating it from the filling frame, which is moved by the transfer device in the direction of the arrow F.

[0037] FIG. 5f illustrates the final condition, in which in the filling station 8 the filled molding box 3'' is again motionless, while in the molding station the table 17' moves fully downward, placing the pattern plate 16 on the carousel 13. Simultaneously, the motion for transferring the frame 12 in the direction of the arrow T begins, while the molded molding box 3 is unloaded onto the transfer line 5. A new cycle begins at this point starting from the condition shown in FIG. 5a.

[0038] The method and the apparatus according to the invention allow to achieve molding capacities of more than 320 cycles/hour which are distinctly higher than those of conventional apparatus. In this manner, in a foundry, it is possible to use a single machine instead of two in order to meet high-productivity requirements.

Claims

1. A method for producing foundry molds by means of molding boxes (3) and pattern plates (16), wherein the empty molding boxes (3) are associated with a pattern plate (16), are then filled with sand at a filling station (8), and then transferred to a molding station (9), where the sand is subjected to packing in order to proue a finished mold;
characterized in that the empty molding boxes (3''), one at a time, enter the filling station (8) along a first entry line (2) and exit after molding from said molding station (9) to advance directly along a second output line (5) which is separate from, and independent of, the first line; the pattern plate (16') being separated from the respective molded molding box (3) and being returned to the filling station (8) on its own in order to be coupled to a new empty molding box (3'').

2. The method according to claim 1, characterized in that the transfer of each molded molding box (3) to said output line (5) occurs directly after the step for packing the sand in said molding station (9).

3. The method according to claim 1, characterized in that the transfer of each molding box (3'') from the filling station (8) to the molding station (9) occurs simultaneously with the exit of a molded molding box (3) from the molding station (9) and simultaneously with the transfer of the pattern plate alone (16) without the molding box (3) from the molding station (9) to the filling station (8).

4. The method according to claim 1, characterized in that before entering the filling station (8), each empty molding box (3'') is covered with a filling frame (12'') which is separated from a molding box (3) that exits from the molding station (9).

5. The method according to claim 1, characterized in that the pattern plates (16, 16'), together with the respective molding boxes (3, 3') placed at the diametrically opposite ends of the carousel (13), are shifted upward to be moved closer to a filling hopper (10) and to the packing head (11), respectively, in order to facilitate the sand filling and packing steps.

6. The method according to claim 1, characterized in that the frame (12'') separated from each molded molding box (3) is transferred by means of a suitable transfer means (24) onto the empty molding box (3'') directly ahead of the region for entering the filling station (8).

7. A molding apparatus for producing foundry molds by means of molding boxes and pattern plates, comprising: a filling station (8) for filling with molding sand one empty molding box (3) at a time, said molding box being associated with a respective pattern plate (16); a molding station (9) for packing the filled molding boxes; a carousel (13) which can rotate about a substantially vertical axis (V) and is suitable to support, at its diametrically opposite ends, two pattern plates (16, 16') which can be coupled to respective molding boxes (3, 3'); a rotation means (15) which acts on said carousel (13) to make it rotate through 180° at a time in both directions of rotation; characterized in that it has an input line (2) for the entry of empty molding boxes (3'') in the filling station (8) and an output line (5) for the exit of the molded molding boxes (3) from the molding station (9), said lines (2, 5) being separate and substantially tangent with respect to the circular path of the diametrically opposite ends of said carousel (13).

8. The molding apparatus according to claim 7, characterized in that said input line (2) and said output line (5) are substantially parallel and are constituted by respective pairs of fixed roller conveyors (4, 6).

9. The molding apparatus according to claim 7, characterized in that it has a first grip means (22) for supporting and releasing an empty molding box (3'') in said filling station (8) and a second grip means (23) for supporting and releasing a molded molding box (3) from the respective pattern plate (16).

10. The molding apparatus according to claim 9, characterized in that said first grip means (22) and said second grip means (23) comprise respective pairs of movable roller conveyors which can be moved on command mutually closer to, and further away from, the axis of said filling station (8) and, respectively, of said molding station (9).

11. The molding apparatus according to claim 7, wherein a filling frame (12) can be selectively coupled to each empty molding box (3'') before filling it, characterized in that it has a transfer means (24) to separate the filling frame (12) from each molded molding box (3) and to move said frame (12) toward said input line (2) directly ahead of the filling station (8).

Drawing