EP0098405A1 - Method of producing large size green sand moulding parts (mould area 1-3 m2) for pouring into flaskless moulds - Google Patents

Abstract

1. Process for producing large format green sand moulded parts by means of boxless moulding, whereby sand is filled in a mould and compressed by applying pressure via a film is that during a first filling stage I, the green moulding sand (5) is applied on a pattern (1) on all sides in one layer in a moulding box (4), which limits the sand surface on the pattern plate (2) and via a spinner (7) which rotates at reduced speed in order to protect the pattern, and is then covered with a flexible film and compressed and during a second filling stage II the back-up (6) is finally applied and the mould subject to final compression.

Description

The invention relates to a method and a device for producing wet cast molded parts in large format for boxless casting.

Boxless casting molds are generally known and have the advantage that there is no need for expensive mold boxes which require maintenance and are subject to constant wear. In addition, with large boxes, the influence of heat leads to deformation, which affects the accuracy of the castings.

In all previously known methods of compacting the wet cast sand, uniformity on all sides is not guaranteed. This is especially true when the model walls have very different heights on the vertical walls. As a result, casting errors due to driving and inaccuracies in the contours are possible.

The object of the invention is to provide a method and a device in which the sand is introduced in such a way that air inclusions in the sand are not possible and the same is easily compacted.

The object is achieved by the inventive features of the characteristics of claims 1 to 3.

The main advantage of the invention is that the elastic film corresponds to a press plate which is divided into an infinite number of press points, which the sand layer, which is approximately equally thick on all sides, is ideally able to compact.

Another advantage is the low environmental impact. The absence of dynamic loads does not cause vibrations. This means that it can also be installed on ceilings with the appropriate static load capacity. The noise level when the sand is introduced is insignificant in stage I and far below the permissible limit values in stage II.

It is also advantageous to save coal dust or a similar additive in the backfill sand, which has a favorable effect on higher gas permeability.

An embodiment of the invention is shown in the drawings. It shows:

Figure 1 - above - station B / 1

The centrifugal head 7 in the feed line for wet cast sand 5 works in principle similar to a sand sling in 2 speed ranges. This makes it possible that, in the case of extremely unfavorable model parts, pre-compression can be achieved for a short time by switching to level II.

The wet cast sand 5 is applied to the model 1 in an equally thick layer and covered by an elastic film 10. This is first sucked in by vacuum 8 on the underside of the press head 11 and, after being placed on the molding box 4, is pressed onto the sand surface by means of compressed air 9 using a pulsator 12. Here, the press head 11 is locked by means of hydraulic cylinders 13. Then the press head 11 is briefly removed via rails 14 and the backfill 6 is applied.

Fig. 1 - below - station D / 1

Model 1, model plate 2 and plate carrier 3 form a unit that oscillates between stations B / 1 and D / 1. In order to quickly remove the air from the molding box 4 when compressing via the film 10, air nozzles 4 'are attached at different heights. Air nozzles 2 ′ for lifting the box 4 are also arranged in the model plate 2, via which compressed air 17 is pressed between the model and the bale. The roller conveyor 18 takes over the final lifting out of the model.

Fig. 2 shows the arrangement of the bar 15 with the sliding bolt 16, which automatically retracts when the bolt 16a is tightened and releases the box for removal.

3 and 4 show the weight, which ensures an even load on the bale. A perfect seal of the parting line between the upper and lower box is given when each box pair is made together.

Fig. 5 shows a molding and casting plant as an example, which represents the favorable transport routes of the various parts of the device.

The way of the lower box leads on the UT line from station B / 1 -G / 1 - G / 3 - B / 2 back to B / 1.

The top box runs through the same stations on the OT line. The transport pallet is placed at E / 1 and runs via G / 1 - G / 2 -H / 1 ... - K / 2 - I / 1 - I / 2 ... K / 3 - L or M - Line to M / 1 and back to E / 1.

The weight is put on at K / 2 and runs over I / 1 into the casting line 1/2 ... After leaving the casting line, the weight is lifted off at K / 3 and transferred to K / 2.

• Gegossen wird in Gruppen von 5-8 Formen, je nach Wandstärke der Gußteile. Jede Form wird vor dem Gießen um 5 gekippt, um eine großflächige Anstrahlung des Oberballens während des Füllens zu vermeiden. Die gegossenen Formen bleiben in der Gießstrecke bis zum Erstarren der Außenhaut stehen. Erst dann wird die Kippstellung in die Waagrechte gebracht, beim Ausfahren auf Station K/4 das Beschwergewicht abgehoben und auf einen ankommenden Ballen auf Station K/3 umgesetzt. Damit beginnt ein neuer Zyklus.

Casting line:

• Casting is done in groups of 5-8 shapes, depending on the wall thickness of the castings. Before pouring, each mold is tilted by 5 to prevent the upper bale from being exposed to large areas during filling. The cast molds remain in the casting section until the outer skin solidifies. Only then is the tipping position brought to a horizontal position, the weight of the weight lifted off when moving out to station K / 4 and transferred to an incoming bale at station K / 3. This starts a new cycle.

Explanatory text for Fig. 5

• A1 Mod-Pl carrier extend / retract
• 2 Mod PI preheating
• 3 Mod PI assembly
• BI sand filling St.l, 2
• 2 Disconnect the F-box OK-UK
• 3 holding bar in OK one.
• Cl milling station
• 2 sand bunkers St.l, 2
• D1 press station
• 2 Press head extended
• 3 film roll
• Turn in E1 retract door pallet / turn in UK
• 2 OK turn
• Insert F1 cores
• 2 Clean the box
• 3 drilling station
• G1 OK UK turn
• 2 OK add OK subtract UK
• 3 OK UK lower H-strips from St.
• Turn G4 OK
• Hl retaining strips n.G3
• 1 ... storage buffer
• I1 control, perfect. Seat of the weighting weight
• 2 ... tilt by ~ 5 ° pour
• Clean K1 Transp.Pal.
• 2 weighting attachment.
• 3 Pull the weight off after transporting to K2
• L1-L4 storage buffer
• M1 Rotate / push off the bale
• 2-5 storage buffers
• N1 conveyor belt of the cooling section

Claims (5)

1. Process for the production of wet cast molded parts in large format for boxless casting,
characterized,
that in the filling stage 1 of the wet casting sand (5) into a molding box (4), which delimits the sand surface on the model plate (2) and via a centrifugal wheel (7), which rotates at a reduced speed to protect the model device, onto a model (1 ) applied in one layer on all sides, covered with an elastic material and compacted. 2. Device for carrying out the method according to claim 1 for compacting the sand in stage I,
characterized,
that a press head (11), on the underside of which an elastic film (10) is held in place by vacuum (8), is placed on the mold box after passing under the model device with the plate carrier (3) and locked by hydraulic cylinders (13), that after that a feed (9) compressed air on the elastic film (10) and this is pressed onto the sand surface, that in a pulsator (12) the pressure is alternately relaxed and rebuilt via an oscillating piston by opening and closing the air outlet opening, and that The resulting air blasts on the film (10), which are transferred to the sand layer (5), produce a uniform compression of the wet cast sand on all sides. 3. Device for performing the method according to claim 1 for compacting the sand in the filling stage II,
characterized,
that for the backfill (6) a sand without the additive "coal dust" is applied via a centrifugal head (7) at full speed, that afterwards the mold filled over the edge of the box is milled off on the way to a press station at the same height and through the press head ( 11) is finally compressed using hydraulic cylinders (13). 4. Device according to claim 2 and 3,
characterized,
that the upper mold box (4) is provided with bars (15) held by sliding bolts (16), which secure the sand bale against falling out. 5. Device according to claim 2 and 3,
characterized,
that in a outer frame (19) a package of weights (20) are loosely inserted, which result in a uniform loading of the bale of form and that under the frame (19) a sealing frame (21) is resiliently suspended, which seals the joint between the upper and lower bales .

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