DE19530872A1 - Mfr. of sand mould in vibration-free manner - Google Patents

Abstract

The moulding machine for compacting moulding sand in a mould box (FK) and for introduction of a pattern (MP) is characterised by the fact that all vertical motions involved in the compaction process, in particular the compacting thrust, are introduced and carried out from above, while the pattern plate lies stationarily on a foundation-near table (MPT). The compaction unit (2; 2a-2e; PR) with the attached frame package (FK, KFR, GPR) is moved downwards relative to the stationary pattern plate. This downward motion is resisted by a spring force which, at the end of the pressing process, lifts the package from the pattern plate without shock or vibration. The machine foundation intended for taking up the forces during the pressing process is free from cylinder units moving press columns or rams. The upward motion of the frame package (FK, KFR, GPR) is achieved by means of hydraulic springs. At least one of the elements (GPR) is movable relative to another element (FK, KFR) or relative to the stationary pattern plate. The pattern plate with pattern (MP) is held to the stationary table (MPT) by vacuum. The pattern may be provided with nozzles producing an upward air stream against the sand mould to ensure vibration-free separation of the pattern and the mould.

Description

The technical field of the invention is the molding machine with which models are depicted in a sand mold in order to to get compacted molding sand in a molding box which is used for Molding molds is used. The invention relates to both a molding machine (claim 1) with which the mentioned pressed sand molds can be produced. The invention relates also a method for compacting molding sand, according to said device can work (claim 11, Claim 17).

The invention is based, the quality of the task To improve sand forms, especially the vibrations lowering the model from the finished sand mold reduce and thus damage to the sand mold during demolding to reduce or avoid entirely.

This is achieved with the invention when all Movements that affect compression from above caused and executed (claim 1), while the Model that is to represent the inner contour of the sand mold, in Press direction is immovably mounted on a table that is close is provided on the base. Due to the fact that it rests on the base the model does not make any upward movements, while the compression process is in progress. They are not pillars or stamp moving lifting cylinder available (claim 2) and below the support element that holds the table (claim 3) No pushing or lifting device intended.

With the static model, which has a Model plate carrier rests on the table mentioned, one minimal movement of the model in the pressing direction and thus high Impression accuracy achieved. It will continue to be the basis created for the model to be firm and stable in the Formed position remains when the sinking or Demoulding begins and is carried out.  

The demolding movement begins with an upward movement Stack of mold frames, consisting of mold box, short filling frame and counterpressure frame, which when moving against a Spring force upwards - against the pressing direction - were biased (claim 11). By building up Spring action is a potential at the moment of pressing end Energy stored, which makes it possible to stack the Lift the frame frame vibration-free and all more or less jerky mechanical side influences, like that in State of the art usual placement of the molding box on a Roller conveyor at the beginning of the demoulding movement is eliminated to let.

After the end of the press, the entire package is held from above Model plate is below z. B. by vacuum (claim 13) on immobile table statically fixed. The pressing movement is on Pressing end switched or relieved, so that the Upward movement of the press head can begin, assisted or even borne solely by the pressure that comes from molding was saved. The hydraulic compression spring or the Gas pressure springs (claim 12) begin the climb or Lifting movements of the box stack (short filling frame, molded box or Mold frame, counterpressure frame) and press the mold box with the molding material gently compacted upwards and lift it vibration-free from the model.

Due to the downward movement of the stack surrounding the sand Frame and due to the statically fixed model, moves the stack of boxes opposite the model and thus experiences one Relative movement compared to the lowest, in particular model-like layers of sand. The force of this relative movement Form box (or: Form frame FK) from one at the beginning of the Compression process predetermined first relative position to Model moved to a model height position. At the end of The molding box only has the position of the compression process taken, the fixed position unchangeable in the prior art of the molded box is directly on, especially with its lower edge of the model plate.  

The relative movement of the molding box compared to the fixed one Model is made in that an intermediate frame - also: Counterpressure frame - the relative movement with and on Model moves past downward, so that at the start of pressing a complete, comprehensive outline of the not yet compacted sand is possible and at the end of the molding the molding box the model height can reach while the counterpressure frame is lower than the model (claim 18). The Movement of the counterpress frame past the model is sand-tight and a regulation ensures that the molding box at the end of the press reached the required end position without the Bottom of a sand mold remnant remains in the counterpress frame or the molding box has been moved too far down while doing so already shifted beyond the deepest layer of sand has been.

Over the counterpressure frame, which goes past the model downwards has been pushed, the demolding force mentioned above Press end applied (claim 19). Over the counterpressure frame the molding box also experiences the constantly acting vibration-free demolding force, so that a reliable, safe and much more precise separation of sand mold and model is made possible.

It has been surprising when training the aforementioned The machine of claim 1 and executing the method according to claims 11 or 17 show that the required machines no longer need extensive foundations or only extremely require minimal installation depths below the floor. You are as To view molding machine with a substantially flat foundation, at which no lifting units under the floor have to reach (Claim 2, 3) or the actual formation in height must be relocated to make room for those below To create lifting units.

All of them, particularly those relating to compaction Movement processes that require high strength and accordingly Must provide counterforce, are initiated from above and directed against a level base.  

So the machine not only does not need a deep one Foundation, but also has a low overall height and is therefore compared to known machines of the prior art from Consider space requirements.

The model and sand mold are almost separated uniform; did the press say B. crooked in the tenth range pressed, so from this minimal misalignment Lowering made without other influences or movement Offset influences on this difficult demolding process can act. So it gets easier even at An excellent shape quality is achieved by misalignment.

Filling the frame stack and the floats in a machine with sand filling station and Compression station can be retractable and extendable Roller strips are taken over at an open bottom U-beams are arranged (claim 10), it can also Principle of reciprocating frames are used that is described in DE 44 17 431 and DE 195 18 320.7.

The U-beams in the press station and in the filling station are from vertically displaceable above piston / cylinder. Are on them in the press station vertically spaced pairs of roller strips attached that can extend and retract horizontally (z direction), but vertically in a fixed distance relationship stand. In the filling station there is at least one in the z direction retractable and extendable pair of rollers with the inverse U-beam vertically movable. Only one that can be moved in the z direction Pair of roller strips is attached to the fixed support columns, see above that an adjustable distance relationship is possible here.

Except for one pair of roller strips, all transfer movements the frame elements caused from above.  

In the molding method according to the invention (claim 11) and Separation process in the molding process (claim 19, claim 17) can do all common pre- and parallel compression principles are used, d. H. before filling the sand, the Mold space can be evacuated, vacuum filling can be used and during pressing and before pressing Effect of an air stream can be exploited for sand compaction.

To further improve the demolding process - or else independently improve - can create a dividing line between model and sand formed after the end of the compaction process be caused by compressed air just before the end of pressing is generated, which is guided from below through the sand (Claim 14). Specific parts are used in the model Nozzles are provided so that the air escapes here in particular can and optimal compaction, including generation a parting line is accomplished. So even very small ones Model slants can be easily shaped and lifted off. After the pressing process is done through nozzles that are specific to difficult games or are embedded in deep balls, before or during the separation ("sinking") of the mold and model air introduced from below so that the flow pressure provides an additional force when lowering, in addition to those that are already spring-loaded be made available for demolding.

The low height of the machine and the vibration-free Demolding is achieved through the initiation and execution almost all vertical movements, especially that Compression movements from above. Not from above caused horizontal movements (z-axis or plane) only with regard to the implementation of the frame elements of Roller bar pairs executed. Even these roller tracks but are used for vertical relocation and relocation movements almost exclusively from above.  

The invention is described in more detail below Exemplary embodiments explained and supplemented.

Fig. 1, Fig. 2, Fig. 3 and FIG. 4 show, in schematic sequence the principle in which a frame stack GPR, FK and KFR by a press frame PR, the a- a press head 2 with single temples 2 surrounds 2 e, to downward relative to a model MP, which is firmly seated on a model plate carrier MPT on a base 1 . The stack on the frame moves in the direction of the arrows v 1 , while the model plate carrier MPT, the base 1 and the model MP remain statically firm and close to the foundation in their position. FIG. 4 shows an exploded view of the different elements, together with the elements 10 , 11 that build up spring pressure, which can be gas pressure springs or a hydraulic system. The molded box FK takes up the sand mold S in the molded state of the sand and is conveyed further in the molded box conveyor line.

Fig. 5a, Fig. 5b, Fig. 5c, Fig. 5d, Fig. 5e and Fig. 5f are schematic instantaneous recordings of the molding operation in which the press frame PR a stack of frame consisting of Kurzfüllrahmen KFR, eigentlichem mold box FK and counterpressure frame GPR downwards compared to a model MP and a model plate carrier MPT, on which MP rests, shifts. Figure 5f shows the separation of the finished sand mold in the FK molding box, which is lifted by the MP model in the v₂ direction without vibration by spring pressure over the GPR counterpressing frame.

6h show Fig. 6a, Fig. 6b, Fig. 6c, Fig. 6d, Fig. 6e, Fig. 6F, Fig. 6g and Fig. Individual operating states of a molding machine is filled with the sand into a filling station F in a frame stack, the compression is prepared and, after the compression of the molding box, it is positioned in the pressing station V for removal and the remaining frame elements which are not removed are moved back to the filling station F.

Fig. 7 and Fig. 8 illustrate a side view and two end views of the filling station arranged from F and adjacent forming station V existing molding machine.

Figs. 1 to 4 illustrate the process steps and alternatives a molding method with "keystone flat machine" of Figs. 7 and 8.

Fig. 1 shows an example of a "package" of sand-forming frame elements. MP (model plate) and MPT (table) are held immovably on table 1 . FK (molding box), GPR (counterpressing frame) and KFR (short filling frame) move downwards with the press frame PR and the press head 2 . The GPR pushes past MP to raise FK to the height of the model. When the sand mold S is finished in the molding box, the FK (molding box) has exactly the position compared to the MP model that it takes up statically in known molding processes.

Slight shifts (underfeed / overfeed) compared to the correct positional relationship of FK and MP are controlled balanced for the next molding process changes settings. The changed settings can determine the basic height (starting height) of the press frame, the amount of oil or the amount of sand.

Fig. 2 illustrates the filling process in which loose sand LS is filled in one or two stages in the stack of frames FK, KFR, GPR.

The pressing and lifting process, in which GPR pushes past MP upwards and downwards, is illustrated by the schematic FIGS. 4 and 3; the latter also the docking of the frame stack (package) to the upwardly moving press head (after molding), which supports the upward movement caused by the springs and takes over the rapid stroke after the spring-assisted slow separation process. Alternatively, roller strips retracted in the z direction can also take over the upward movement controlled from above.

Fig. 4 illustrates the intermediate element displacement (GPR) against the hydraulic springs 10 , 11 and (during pressing) lowering the molding box FK to the model plate MP. The springs 10 and 11 shape the beginning and the first phase of sand mold separation without vibration for the sand mold S.

Fig. 5a to 5f illustrate the actual compression process, carried out in which caused only from above movements. . Seen in Figure 5a of the stack of frames is KFR (short: filling frame), FK (flask) and GPR (Gegenpreßrahmen) serving as unterster frame rests the stack on a schematically illustrated spring system and is carried by this. The spring system is represented by two springs 10 , 11 , which can be a hydraulic system or a gas pressure spring system. The model plate carrier MPT sits firmly on a table 1 , which was shown in Fig. 1. A model MP, which specifies the shape S to be formed, sits on the model plate carrier MPT.

In Fig. 2 illustrated press head 5a has a plurality of individual stamps 2 a, 2 b, 2 c. . . and a peripheral edge web, which is to be regarded as a further press frame PR. It is designed to sit on the end face of the short filling frame KFR in an essentially airtight manner and to apply vertical thrust forces to the frame stack. The press frame PR is firmly connected to the carrier 2 of the compression unit 2 a to 2 e, in which the piston-cylinder units for the individual stamp 2 a. . . 2 e are attached.

Fig. 5b shows the beginning of docking, in which the press frame PR airtightly seated on the end face of the KFR. The vestibule is closed and sealed, an air pre-compression can now be induced to slightly compress the sand towards the mold MP, or it is immediately caused by the press ram, which evenly downwards in the direction v₃ move relative to the press frame PR. The latter is shown in Fig. 5c.

In Fig. 5b and 5c of the press frame PR remains in a fixed axial position, so moving the stack frame KFR, FK, GPR not down.

The movement of the frame stack only begins in FIG. 5d, here press frames PR and the press dies 2 a, 2 b, 2 c, which are slightly advanced according to FIG. 5 c, move. . . together downwards and compact the sand S above the MP model. The counterpressure frame GPR pushes against the pressure of the spring system 10 , 11 past the MP model, e.g. B. on the model plate carrier MPT or beyond. The molding box receives its final position relative to the model, as is also shown in Fig. 5e. In addition, in Fig. 5e a final compression v₄ is selected, in which the ram again move downward relative to the press frame PR remaining in its height. The sand mold S gets its final shape, the short filling frame KFR no longer contains any residual sand.

In Fig. 5e, a lower stop is drawn, to which the counterpressing frame GPR strikes before the final compression of the press ram begins. In this way, increased accuracy and strength of the shape is possible, but it is not absolutely necessary that the counter-press frame GPR has already reached its lower end position when the individual punches move relatively downward with v₄ relative to the press frame PR, that is, if the individual punches perform an additional downward movement relative to the press frame PR. These molding processes can overlap more or less.

The end of molding is reached in Fig. 5e, in Fig. 5f the vibration-free lowering is shown by the upward spring pressure F₂ of the hydraulic system 10,11 . A further raising of the molding box to a height that allows removal, but which is no longer critical with regard to vibrations, can be carried out by pivoting levers 20 a, 20 b (see FIG. 3) or by retracted roller strips (see FIG. 6h) .

The upward movement v₂ is largely caused by F₂.

Figs. 6a to 6h show transport movements, vertical displacement movements and return displacement operations of the frame stack or individual elements of the context stack, except in FIGS. 5a to 5f compaction already explained and vibration-free counterbore of the sand mold S. In Fig. 6a, 6b, 6c and 6d, movements in the filling station F are explained.

The sand is weighed in a filling bunker ST and the defined amount is filled. The sand is loosely present in the ST filling hopper, it is arranged in the center of the machine frame. The laterally retractable and extendable roller strips, each consisting of an opposite set of rollers 31 , 30 that can be retracted and extended in the z direction, enable the controlled upward and downward movement of the entire stack of frames or individual elements for compression preparation movements. The horizontally retractable and extendable roller sets 31 , 30 are held in the filling station F on a U-shaped support. The U-shaped carrier consists of an upper cross strut 34 c and two downwardly projecting legs 34 a, 34 b, which point down to the left and right of the box stack. Two U-shaped supports can also be provided next to the sand filling shaft ST. Corresponding lifting units 36 a, 36 b are provided on the upper cross strut 34 c, starting from a fixed machine head 3 .

Fig. 7 (in side view) and Fig. 8 (in two end views) illustrate the U-beams 34 , 35 and the lifting units 36 a, 36 b and 37 a, 37 b attached to the machine head 3 and acting on them from above.

Fig. 6a illustrates a held by the roller strips 31 Kurzfüllrahmen KFR, which lies between the sand-filling shaft ST and the bottom supported on a second set of rollers pair 30 other elements of the context stack, the model MP, the Gegenpreßrahmen GPR and the molding box FK. They are moved upwards with the roller bars 30 (controlled by the upward movement of the U-frame 34 ), take the filling frame or short filling frame KFR held by the roller bar 31 with them and dock at the filling station ST, as is illustrated in FIG. 6b . For this purpose, the roller strips 30 , 31 are displaced vertically by lifting the U-shaped frame via the lifting units 36 a, 36 b. The same height of the filling frame KFR is obtained because the roller strips 31 are not guided in the U-shaped support 34 and do not change in their height.

Fig. 6c illustrates the filling of the molding sand, which can be done with the help of a vacuum acting from below (below the loose sand LS to be filled in) to bring the sand into difficult contours and to fill these contours optimally with sand and in a first stage pre-compress.

The pair of roller strips 31 has previously been extended in the direction of the arrows shown in Fig. 6c z₃₁, so that the stack of frames can be moved past the upper pair of roller strips 31 upwards.

Filling with loose sand, which was also indicated schematically in FIG. 2, can take place in two stages. Either the ST bunker is divided into two or two different bunkers are used. The second bunker can be located in the filling shaft of the first bunker, it can also be swiveled into place of the first bunker. The respectively opened flaps 40 of the blind closure in FIG. 6c are representative of the filling.

Either the stack of frame elements filled with sand is now lowered and placed on a transport route to the compression station V (cf. FIG. 6d) or the bunker ST moves upwards.

The next box thrust v _FK causes the stack, which may be filled with pre-compacted sand, to be conveyed into the compacting station V. The compression station can be seen in FIG. 6e, it is located next to the filling station which has been shown in FIGS. 6a to 6d. Also Fig. 8, left panel shows the pressing or compacting station V.

In station V, the stack of the aforementioned frames KFR, FK, GPR and the model plate MP and the model plate carrier MPT is lowered by means of a further pair of roller strips 33 in order to be placed on the statically fixed table 1 in FIG. 6e. The downward movement takes place by lowering the U-beam 35 on which two vertically spaced pairs of roller strips 33, 34 are fixedly arranged.

The pair of roller strips 33 is moved out in the z₃₃ direction after settling and the package is prepared for compression by being clamped, for. B. by tappets, by cams or by a vacuum clamp.

In Fig. 6f the compression device 2 is lowered, which can be done by lifting cylinders 37 a, 37 b. The compression device is also arranged on the U-beam 35 .

The compression device 2 has many internal single punch 2 a. . . 2 e and a circumferential press frame PR, which is seated in Fig. 6f on the upper end edge of the frame stack. This creates an essentially airtight contact between the press frame PR and the upper edge of the frame stack. The compression process, which has been explained with reference to FIGS. 5a to 5f, takes place according to FIG. 6f.

After the compression according to FIG. 5e and when lowering according to FIG. 5f, the vibration-free separation is obtained by relaxing a hydraulic system into which the counterpressure frame GPR has shifted during the compression process against a mechanical stress building up (hydraulic "spring").

After completion of the low-vibration slow stroke caused by the hydraulic system 10 , 11 , retracted roller strips 33 take over the further separation process according to FIG. 6h. The molding box is brought up to a height in a rapid stroke in which a transport path is provided. The KFR can be held over the other pair of rollers 32 and also moved upwards. The upward movement is carried out via lifting units 37 a, 37 b, which raise the press head 2 and the U-beam 35 from above.

The KFR is raised to a level at which it can be conveyed back to the sand filling station according to FIG. 6a. The molding box with the fully molded S sand mold is raised to the level of the transport path. The next box push feeds it out of the compaction station. The state shortly before the molding box FK is conveyed out is represented in FIG. 6h.

A new sand filling of the box stack in Fig. 6a can begin, the cycle is closed.

The control of the press rams during pressing according to FIGS . 5b to 5e can be carried out in such a way that they move relative to the press frame PR in such a way that they execute a movement which is related to the effective sand heights above the model. The stamps move down little when there is little sand and a high contour, the stamps move down more when there is a lot of sand and a flat contour.

Shortly before the end of the press, when the press frame PR, molding box FK and counter-press frame GPR have reached the lowest position, the separately arranged hydraulic system of the multi-punch switches to a press push, in which all punches 2 a to 2 e are moved simultaneously and evenly in the pressing direction. From the different heights of the multi-ram, caused by the previously mentioned compensating movement, the incoming pressing force results via a separate line control so that the different sand pillars experience different forces. The separate switching can be done in such a way that the different pressure forces lead to the same compression in all columns.

The movement of the press thrust ends before the end of Force application, with the press frame PR on the upper edge of the frame stack KFR, FK, GPR has pressed and the GPR over MPT / MP has moved over to the sand inside condense and the force from above as well as the shift from GPR to make MPT / MP effective.

With the end of the press, the hydraulic spring 10 , 11 of the counterpressure frame is increasingly tensioned in order to prepare the gentle springback, which enables the vibration-free lowering.

After completing the pressing, the stapled package PR-KFR- FK up to the press frame PR still in a certain Preload, although the force of the press head what has been caused by the tensioned hydraulic spring has disappeared is. The certain force of the tensioned hydraulic spring ensures a vibration-free depression process and lifts  the press head at the same time. The critical phase of separation compacted molding sand and model are thus completed.

In order to get an exact height position of the molding box FK, relative to the model, the machine has a controlled one Hydraulic control loop, based on a height measurement of the molding box appeals. When pressing with the GPR, a spill or a Undershoot reached, so the molding box FK at the end of the Pressing process does not have the exact height, the transfer or Underfeed detected by the height measuring device - it can also be arranged on the counterpressure frame GPR - and the Hydraulic unit adjusted. The next impression will be taken the basic height from which the hydraulic unit starts to press, via a separate height shift point (Oil pressure volume compensation) shifted. The impact (Press force) of the press PR for the next impression stay the same.

An alternative way of regulation is one disproportionate displacement with the same pressing force of the Press frame PR, but with changed hydraulic fluid in the Hydraulic spring.

An example illustrates the regulation, whereby as reference and System sizes standardized units are provided.

F _GPR = 80 units, the stroke start of the press frame PR is at a height of 5000 mm, a system pressure of 500 units is provided, the impact force of the oil leading to a press force F _PR = 2000 units.

As a result, it is assumed that the sand shape protrudes somewhat, d. H. the division level of the upper box and lower box is not is achieved exactly. A piece of the sand mold stands down above, the molding box FK was not deep or wide enough lowered ("underfeed").  

A molded box made in this way is declared as a reject mold, e.g. B. no sprue is milled. In the same way also a "pass" a corresponding signal for declaration the form as a reject form.

To regulate the underfeed mentioned above in the example, the spring tension F _{GPR is} reduced, in the second molding process it is F _GPR = 78 units. The stroke start of the press frame PR is also reduced (at a height of 4995 mm), the system pressure is 505 units. The impact force of the oil in the hydraulic system leads to a pressing force F _PR = 2000 units.

In the example, an exact height of the molding box is achieved after molding is complete. If there is again a slight control error, the spring tension is reduced again. The steps by which the spring tension F _GPR can be reduced can be reduced as the target (the exact height of the FK molding box) is reached.

Claims (20)

1. Forming machine for compacting molding sand in a molding box (FK) and introducing a model contour in the compacted molding sand, in which all vertical movement processes relating to the compacting, in particular the compacting thrust, are initiated and carried out from above, the contour of the later sand mold forming Model (MP) rests immovably on a table near the base ( 1, MPT) when pressing in the pressing direction. 2. Molding machine according to claim 1, in which a support element (base, 1 ) for the forces occurring during the pressing is provided as the machine base, which has no lifting cylinders moving columns or stamps. 3. Molding machine according to claim 1 or 2, in which the support element ( 1 ) is arranged approximately at ground level and below the support element ( 1 ) no pushing / lifting movements are arranged. 4. Molding machine according to one of the preceding claims, in which the model-forming "package" (FK, KFR, GPR) is held from frame elements after the end of the press from above ( 20 a, 20 b) and with the compression unit ( 2 ; 2 a- 2 e ) upwards - from the model plate and table ( 1, MP, MPT). 5. Molding machine according to claim 4, in which after the end of the downward movement of the compression device ( 2 ) a pressure of at least one on the base ( 1 ) or table (MPT) arranged hydraulic spring ( 10 , 11 ) acts on the package upwards to the end of the press Lift the molding box (FK) upwards from the model (MP). 6. Molding machine according to one of the preceding claims, in which

• - A two-part sand bunker on which the sand-absorbing package is placed; or
• - Two sand bunkers are placed one after the other over the package, for multiple (time-spaced) filling of the package with molding sand; or
• - Two filling bunkers, one on top of the other, carry out a filling at intervals.

7. Molding machine according to one of the preceding claims, in which

• (a) a sand-forming "package" consisting of a molding box, filling frame and counterpressing frame (FK, KFR, GPR) is not moved upwards in the direction of the compression device immediately before and during the pressing process of a compression device ( 2 );
• (b) the package (KFR, FK, GPR) which laterally delimits the sand mold (S) is moved downwards by a frame element (PR) during pressing, which is arranged around the stamp compression arrangement ( 2 ; 2 a - 2 e) and rests essentially sealingly on the top of the package.

8. Molding machine according to claim 7, wherein the at least one element (GPR) of the package against at least one other element (MP, MPT) of the package or immovable relative to it held unit from model plate and model table (MP, MPT) is relatively movable in the pressing direction. 9. Molding machine according to claim 8, in which the movement of an element of the package is directed downwards relative to the model (MP) and a spring pressure which builds up (hydraulic pressure, gas pressure, mechanical spring pressure) is directed against the downward movement ( 10, 11 ). 10. Forming machine in which the transport, vertical displacement and relocation processes are carried out on horizontally (z-direction) extendable, vertically displaceable and / or vertically fixed roller strips ( 30 , 31 , 32 , 33 ) which are not active during the pressing of the sand mold or are extended horizontally, the vertical movements of most roller strips ( 30 , 31 , 32 , 33 ) being guided by vertical struts ( 34 a, 34 b, 35 a, 35 b), which the legs of U-beams ( 34 , 35 ), each of which is connected via an upper horizontal support beam ( 34 c, 35 c), each of which has at least two overhead lifting units ( 36 a, 36 b, 37 a, 37 b) in a sand filling station (F) and compression station (V) can be moved up and down. 11. A method for compacting molding sand over a model plate (MP, MPT) and forming a sand mold (S) for casting processes, in which

• (a) a compression unit ( 2 ; 2 a- 2 e, PR) with a stack of boxes or frames (“package”) docked thereon is moved downwards relative to a statically lying (MPT) model plate (MP);
• (b) the downward movement is counteracted by a spring force ( 10 , 11 ) acting on the package (FK, KFR, GPR), which at the end of the press lifts the package off the model plate (MP) without vibration.

12. The method according to claim 11, wherein the spring force ( 10 , 11 ) is applied via a hydraulic control or via gas pressure springs to the lowest frame (GPR) of the stack of frames (FK, KFR, GPR). 13. The method according to claim 11 or 12, wherein the Model plate (MP) firmly on a vertical immobile table (MPT) is held, especially by Vacuum pressure. 14. The method in particular according to one of claims 11 to 13, in which one of the nozzles arranged in the model (MP) upward air flow against the sand mold (S) is directed to the vibration-free excavation of the Model (separating model and shape). 15. The method in particular according to one of the preceding method claims, in which, before the end of the downward movement of the sand-forming package (KFR, FK, GPR), the compression unit ( 2 ) via an in particular separate hydraulic system with unchangeable single-punch stroke positions ( 2 a, 2 b. 2 e) is moved downwards in total (parallel thrust). 16. The method according to claim 15, wherein the parallel thrust in temporally back section of the compression process, in Time range shortly before to shortly after the end of the Downward movement of the counterpressure frame (GPR) in the package relative to the model (MP). 17. Molding process for sand molds, in which the molding box (FK), which contains the sand mold (S) in the fully compacted state, before the sand begins to compress above or below - the inner contour of the sand mold (S) determining - model (MP) is held and only with the Compression process postponed to model height. 18. Molding process according to claim 17, in which between Molding box (FK) and model (MP) in compression direction Slidable intermediate frame (GPR) is held up during the compression process close to the side (sand) Model (MP) moved past. 19. Separation process in the molding process according to claim 17 or 18, in which

• - The molding box (FK, KFR) is lifted from the model (MP) by means of a spring pressure ( 10 , 11 ) that has been built up (essentially continuously) during compression; or
• - The intermediate frame (GPR) via a spring pressure ( 10 , 11 ), which was built up during compression, is raised past the model from below the model (MP) in order to assume its rest position at the height of the model.

20. Molding machine according to one of claims 1 to 10, for carrying out the method according to claim 15 or claim 16, in which on the compression unit ( 2 ; 2 a- 2 e) individual stamps and a peripheral edge web (PR) are provided, which together downwards are movable, with the individual stamps being additionally displaceable relative to the edge web.