WO 95/31302 (Kuenkel-Wagner) shows a machine which permits the filling and molding of sand molds in pairs at an accelerated speed and by using a movement of a single stack of boxes comprising a model, a molding box and a filling frame carried by a carrier plate and being moved together from a (single) filling station to a (single) compacting station, said movement being a linear one. After molding, said filling frame is returned into said filling station (above a straight conveying line) and said model is also returned into said filling station (below said straight conveying line), said return movement being effected substantially simultaneously in two separate cycles. Thereby, two rectangular cycles above and below said conveying line are obtained, whereas said conveying line passes between said two vertically oriented cycles. Molding boxes are clocked into said machine arrangement.

Other machine arrangements of prior art, often being called"twin machine", see EP-B1 582 855 (BMD) or EP-B1 697 929 (Kuenkel-Wagner). Such machines comprise two spaced molding machines, each consisting of a compacting station and a filling station being arranged along a straight conveying line. They have a distance being an odd multiple of the box length, so that a double thrust of molding boxes always results in one machine molding one type of molding boxes and the other machine the other type, said molding boxes being equipped with models for an upper and a lower box in said molding machine. Said molding boxes are alternatively arranged on said conveying line in a linear direction and are moved in said linear direction by a cylinder, providing the thrust length as one transportation step.

One object of the invention is an improvement of the conveying performance and the molding performance of granular molding material compacting machines by a new arrangement and a corresponding new method. A further object of the invention is to realize energy savings in said molding material compacting machines. A further object of the invention is to minimize synchronization overhead in control of the groups of machines.

The machine arrangement according to the invention comprises two compacting machines, one nested into the other and each comprising a compacting station and a filling station. A pair of machines, having a filling station and a compacting station, is arranged close to each other and apart from said closely neighbored machines, a markedly spaced pair of machines, having a filling station and a compacting station, is provided, all of them being arranged along a straight conveying line. Thereby, a machine arrangement is obtained, wherein said two filling stations are closely neighboring each other, directly followed by said two compacting stations. The first filling station supplies the first compacting station with filled molding boxes and the second filling station supplies the second compacting station. The closely neighbored filling station and compacting station inside said machine arrangement does not work together and for another, said filling station not supplying the neighbored compacting station, but the one following thereafter.

This invention may be applied to three, four or a number of machines, so that firstly three filling stations and subsequently three compacting stations or firstly four filling stations and subsequently four compacting stations are arranged in a linear direction of said conveying line.

Each molding frame thrust (in short"box"thrust) moves the box stacks known from the above cited prior art by a direct thrust from said number of filling stations to or into said number of compacting stations. Thereby, two, three or four box stacks, each of them being filled, are simultaneously moved in linear direction and then are substantially simultaneously compacted in said group of compacting stations. After compacting, said arrangements of box stacks are separated in axial direction into their individual elements, said separation being effected by axial movements and a lifting table control and a corresponding controlled turning in of roller conveyors, so that after said separation in axial direction, a group of filling frames is positioned above said conveying line and a group of model plates (or pattern plates), particularly with model plate carriers, is positioned below said conveying line, whereby they are lined up as a group in linear direction. They are returned each as a group into a group of filling stations above and below on (turned in) conveyor sections provided therefore, where they are again assembled to groups of box stack arrangements by axial movements and lifting devices, said box stack arrangements being filled with molding material to move them simultaneously linearly into said group of compacting arrangements in the conveying direction of the conveying line.

As far as it is referred to a filling machine or a compacting machine in the claims, said terms have the same meaning as the terms of"filling station"and"compacting station".

A compacting station and a filling station together are a"molding machine"having the functions of filling with molding material and compacting of molding material in a molding box.

Therefore, when referring to two filling stations in the claims, this means at least two of them, as well as referring to (at least) two compacting stations.

A group of box stacks is linearly moved by a double thrust (a thrust of double length), if two filling stations are provided, by a triple thrust, if three filling stations are provided, and by a quadruple thrust, if four filling stations are provided. The thrust number corresponds to the number of filling stations or"filling arrangements"at the beginning of the machine arrangement.

When moving the box stacks out of said filling stations and into said compacting stations, said box stacks are moved forward over a specified distance, said distance being larger than a sum of distances of said filling stations, particularly as large as a distance between two filling stations plus a distance between a filling station and a first compacting station, or if three filling stations are provided, twice the spacing between two filling stations plus a distance between the innermost filling station and the innermost compacting station.

During their movement in linear direction, said box stacks maintain their relative distance in relation to each other. Moving two, three or four molding boxes, corresponding to the number of linearly moved box stacks into a compacting station results in moving the same number of compacted molding boxes out of the last of said compacting stations.

When moving a group of box stack arrangements forward, a corresponding number of filling frames is moved back into said filling station above said conveying line, and models, carried by model carriers, are moved back into said filling station below said conveying line. Two groups of respectively equal box stack elements circulate in the machine arrangement at different levels. The number of box stacks per group being determined by the number of compacting stations (or filling stations), rowed up along the conveying line.

As far as a distance between individual machines next to each other in said machine arrangement was mentioned above, said distance is not measured between an output edge and an input edge of adjacent machines, but from a respective machine center to a neighbored machine center of two adjacent machines, each machine center being defined by a supposed plane extending through said machine and being oriented perpendicular with respect to the transportation direction of the conveying line. In the entire machine arrangement, all of said center planes extend substantially in parallel with respect to each other, so that individual distances between machines are to be understood as distances between the center planes of said machines.

Brief introduction to the drawings, to show examples of the invention.

Figure 1 illustrates the starting position, on the basis of which the work flow of the machine shall be described.

Figure 2 illustrates the beginning of the filling process and the beginning of the simultaneous compacting process in both sections of the machine arrangement, namely the filling section 20 and the compacting section 30, comprising two filling stations 20a, 20b and two compacting stations 30a, 30b respectively.

Figure 3 illustrates the situation after filling and after compacting.

Figure 4 illustrates the upper and the lower cycle by moving back the filling frames FR above a conveying line 10 and the models M (also called: pattern) and model carriers MT (also called: pattern bolster) below said conveying line 10 to return to the position according to Figure 1.

Figure 5 illustrates an embodiment of a machine arrangement having three compacting stations and three filling stations 20a, 20b, 20c which are nested according to the concept of Figure 1, so that the first filling station 20c fills a box being compacted by the innermost compacting station 30a provided that a triple thrust of three closely neighbored box stacks is effected from the group of filling stations to the group of compacting stations.

A general view of the Figures shows that a work flow may be described best by shortly explaining the working conditions of the machine arrangement according to Figures 1, 2,3 and 4 at first. Figure 1 illustrates a starting position of the machine arrangement having two filling machines as filling stations 20a, 20b in a filling section 20 of said machine arrangement and two compacting machines as compacting stations 30a, 30b in a compacting section 30 of said machine arrangement. Said filling section 20 is also designated a group of filling machines. Said compacting section 30 is also designated a group of compacting machines. A group of machines defines a number of individual machines arranged close to each other in a conveying direction 10 of a conveying line, marked similarly in all figures and designated here as a molding box roller conveyor 9.

Accordingly, the machine arrangement has a first group of machines 20 for filling molding boxes FK moved along the conveying line and a second group of machines 30 for compacting granular molding material F in said molding boxes, which were filled before, and passing said boxes filled with compacted molding sand F further on a continuing portion of said conveying line 9.

Figure 1 illustrates the starting position of said first and second machine groups 20,30.

After entering two empty molding boxes FK, at the end of said two machine groups two readily molded boxes (boxes containing compacted granular material), designated 41,42 in Figure 4, are automatically transported in direction of a reversing arrangement which is not illustrated here. Simultaneously with said transport, models M lowered down in said compacting group 30 are returned below said conveying line 9 and filling frames FR lifted up in said compacting group are returned above said conveying line 9 from Figure 4 back to Figure 1 into said filling group 30, illustrated there. The return transport is effected by automatically introduced roller conveyors 14,14a above and such conveyors 12,12a below said conveying line 9.

Based on the starting position according to Figure 1 (which was reached from Figure 4), Figure 2 illustrates a condition of the machine arrangement according to which the filling process of the molding boxes in the filling group is just beginning, while the compacting of the molding boxes in the compacting group is also just beginning. In said filling group, lifting arrangements, illustrated as lifting cylinders 21 a, 21 b, firstly take over model carriers MT during lifting, on each carrier a model M resides, subsequently the (still empty) molding boxes FK, which have been pushed in by a double length thrust (or clock) over said roller conveyor 9, and thereafter the filling frames FR waiting above said conveying line 9 on roller conveyors 12a. They are further lifted in vertical direction until reaching a filling position shown in Figure 2 in said filling group 20. Simultaneously with the lifting movement in the filling group as described above, more powerful lifting cylinders 31 a, 31 b provided in said compacting group 30 move their pistons in upward direction. Thereby, second box stacks, each comprising a model plate carrier MT, a model M, a molding box FK and a filling frame FR, are lifted until the upper edges of the filling frames FR contact sealing frames in the compacting group. The molding spaces in a group of box stack arrangements, shortly designated with P1 and P2, are closed and sealed by circumferentially arranged sealing portions according to Figure 2.

Figure 3 illustrates the end of the filling process started in Figure 2. Closure means in the filling group having been opened and sand quantities dosed in the sand containers, which are positioned above, having been filled into the molding boxes and filling frames FK, FR arranged thereupon. In the filling group, the roller conveyors 12a illustrated in Figure 4 are automatically withdrawn to permit a lowering of the box stack group by lifting cylinders 21a, 21b, until the level of the conveying line 9 is reached. In the compacting group 30 according to Figure 3, the precompacting and final compacting of the molding material F occurs substantially simultaneously with the filling in the filling group 20. By opening air valves, air streams into the closed molding spaces

through the sand and through nozzles provided in the models M and the model plate carriers MT, into hollow spaces of the model plate carriers and further into the atmosphere. Thereby, the molding sand F is caused to flow, thus being transported in deep model contours. Also hollow spaces which occurred during filling are filled with sand. The flowing sand becomes deposited at the models and is precompacted depending on the predetermined values (air volume, flow time) and the provided nozzles. Subsequently, final compacting of the sand is effected by a predetermined advancing of illustrated pistons of multi-piston squeezing heads.

Figure 4 illustrates the two box stack arrangements P1 and P2 as already mentioned, which are filled with sand and which may be moved to the right on intermediate roller conveyors 11 to reach the compacting group. In the compacting group, the compacting process of the group of box stack arrangements being present there is finished and a separating step has already been effected comprising lowering of the model M and lifting of the filling frame FR. Said filling frames FR are illustrated above a conveying line 9 and said models M with model carriers MT below said conveying line 9. Said condition is reached after the compacting process according to Figure 3 is terminated.

Thereafter, the lifting cylinders 31 a, 31 b with the readily compacted molds are lowered in the compacting group. During said process step, the group of filling frames FR is placed on laterally introduced roller conveyors 12 which are visible in Figure 1.

According to Figure 4, the remaining box stack arrangements comprising molding box, model and model plate are moved further downward to softly place the molding boxes on intermediate roller conveyors 11 a, 11 b. Thereafter, the molding boxes are separated from the models M at a reduced speed in such a way that during the separation step the molds have time for aeration. The lifting cylinders 31 a and 31 b continue lowering until their starting position, placing the model plate carriers MT on roller conveyors 14 beforehand. Placing is effected at a reduced speed. The condition as illustrated in Figure 4 is the beginning of the return transport of the models M with model carriers MT, shown by arrows.

By pushing two empty molding boxes into the filling group 20 according to Figure 1, the molding boxes 40 filled with sand are moved into the compacting group 30 and the finished mold halves 41,42 are transported away. Simultaneously, a group of filling frames FR above and a group of model plate carriers MT with models M below return into the filling group 20 on introduced and driven roller conveyors 12,12a and 14,14a.

During said return movement, the models may be cleaned and sprayed.

The cycle back to Figure 1 closes and renders the work flow of the entire arrangement apparent.

A group of a box stack arrangements, comprising a model carrier MT, a model M, a molding box F and a filling frame FR, which latter being filled with molding sand F, is moved from the filling group 20 into the compacting group 30 simultaneously and without changing its relative distance. Said linear movement is the best visible between Figure 4 and Figure 1 and is indicated by arrows in Figure 4 in a group comprising two molding box stack arrangements P1 and P2.

Simultaneously with said forward movement, the group of filling frames FR returns above a conveying line 9 and a group of model plates M and model plate carriers MT returns below said conveying line 9 into the filling group.

Thus, according to the embodiment shown, comprising two machines in the filling group and two machines in the compacting group, two groups of box stacks circulate simultaneously, one of said box stack arrangements being assembled, whereas the other one being separated, with the exception of the condition according to Figure 2, in which both box stacks are at the same time assembled.

The distance of the individual machines results from Figure 1, showing the respective center planes (marked by a dot-dash line). The two filling machines as two independent machines have a distance c. The two compacting machines as two independent machines have a distance b. Between the innermost filling machine 20a and the innermost compacting machine 30a, a distance a of the center planes of said machines is provided. The sum of all three distances defines the total distance d between the center plane of the first filling machine 20b and the last compacting machine 30b.

In the illustrated embodiment, all distances a, b and c are equal and correspond substantially to the distance between the centers of rowed up and transported molding boxes in the conveying line 9. This is the reference distance length of the molding box transport, i. e. substantially the linear extension of the molding boxes FK which are clocked along the conveying line, said linear movement being represented by reference numeral 10.

The molding box FK as illustrated in Figure 1 is moved forward over a length or a distance c+a, the neighboring molding box FK is moved over the same distance, so that they reach the compacting group in a respective box stack P1, P2 according to Figure 4

and are positioned there at the respective machine centers. This distance c+a is less than c+a+c as in a conventional twin machine, which is 3c, when c=a.

When more than two filling machines are provided, more than two compacting machines are provided. Such an arrangement of machines is shown in Figure 5, having the same distances as described with respect to Figure 1. Reference is made to the details given in relation thereto. Each group of box stacks P1, P2 and P3 is increased by one box stack and three box stacks are simultaneously conveyed in a linear direction 10 from the filling group 20 into the compacting group 30, substantially simultaneously returning an upper group comprising three filling frames FR and a lower group comprising three models into the filling group 20 on turned in roller conveyors.

Figure 5 shows the group principle. A first group of box stacks moves forward, while a group of filling frames is returned above a conveying line 9 and a group of models is moved back below said conveying line. In this embodiment also two groups of box stack arrangements circulate in the machine, each group comprising one more box stack than described according to Figure 1.

The total length of the machine arrangement is slightly more than d, d=3c+a+3b. The length of movement of a stack arrangement becomes a triple thrust 2c+a (which is 3c, when a equals c). This triple thrust is longer than 2c, but less than 4c.

The machine arrangement as described, having two filling arrangements and two compacting arrangements, is more advantageous than the twin machines known from prior art. Different models (a model pair comprises a model for the upper box and a model for the lower box) may be molded simultaneously. Thereby, bottlenecks in other foundry sections may be avoided. If twin machines are used e. g. for a core-intensive production, a bottleneck in the core production may be caused, because a corresponding high productivity is required there. Bottlenecks in core production, however, cause a more frequent model change and a loss of time. By using the machine arrangement as described above, the simultaneous molding of two different model pairs, one in the first group of box stacks and a second one in the second group of box stacks, may avoid bottlenecks in core production. If three box stacks per group are provided, even three different models pairs may be filled simultaneously and thereafter compacted simultaneously.

It was found that a machine working in the described way has a more favorable total consumption of energy than the twin machine, and also, the production cost of such a nested machine arrangement is not so expensive as that of two spaced independent molding machines along a conveying line wherein in the course of the conveying line a filling arrangement, a compacting arrangement and again a filling arrangement and a compacting arrangement are arranged alternately. Between the innermost machines, i. e. the first compacting arrangement and the subsequent filling arrangement, a distance is required by function, because an odd multiple of the reference length (partition length) is required so that the machines may alternately mold an upper and a lower flask (or: box).

In the arrangements described according to Figures 1 and 5 no alternation of the machine types is provided, but at first a group of similar filling arrangements is provided directly, followed by a group of similar compacting. This also reduces synchronization problems caused in the prior machine assembly, when increasing the number of operating machines.