Thanks to Belloi & Romaqnoli for this great animation of the green sand foundry process.
Green Sand Preparation, Tight Flask Molding, Rotary Sand and Casting Cooling Shakeout Technology
"A modern foundry sand preparation system must meet two fundamental requirements, it must produce quality sand and it must continue to deliver this quality over time. Belloi & Romagnoli systems guarantee the supply of quality sand with the right compatibility and green strength with a temperature level below 45 degrees, which is permeable and constant over time. Now, let's see how.
Belloi & Romagnoli has designed the sand and casting cooling drum to enable modern foundries to cool the sand and the casting simultaneously to aid cleaning and to allow for use of an extraction system to monitor the quantity of fines. A vibrating conveyor carries the molds from a knockout system to the drum. Cooling is achieved by evaporating the residual moisture from the return sand and also the water added as required by a system that consists of two parts, one in the loading and one in the exit zones.
An extraction and filtration system removes the steam and fines generated by this process. By rolling the castings and sand around inside it, the drum not only cleans and empties costings from cause, but also mixes the return sand to a uniform consistency, cutting milling times. At the end of the process, the sand and the clean cooled castings move on to a screening sector where they're separated.
The mixer is rightly considered the heart of the foundry sand system. It's the most important machine where the molding sand is restored to the ideal conditions. The model designed by Belloi & Romagnoli assures constant quality, high output, reliability and low maintenance requirements. Our mixes feature an efficient mixing unit comprising two or three rotary units, each turning on its own axis, which cover the entire surface of the ceramic lined tank. An innovative hydraulic drive unit supplies the energy to power movement of the entire rotary assembly. The water is fed in as quickly as possible so that it spends the longest possible time in contact with the bentonite for more effective activation.
Once the return sand has been added, the additives follow. The properly wet sand retains and incorporates them more effectively to optimize bentonite activation. By minimizing the time taken to add the various ingredients, we extend the time available for mixing the real active phase and the cycle which takes place into separate parts.
Pre-mixing. The tank contains the washing water and the return sand. The sand is wet to prepare it for the addition of the other additives. Intensive mixing is the phase when all the ingredients are together in the tank and react to give the sand the required chemical, physical, and mechanical characteristics. This takes from 80 to 90 seconds.
The quality of the mixing cycle is achieved through the combination of the intensive mixing action and the GSC automatic sand control system, which controls operation of the mixer and the feeding of water and additives to produce quality sand that remains constant over time.
An automatic laboratory measures the physical properties of the samples of sand taken at the mix of outlet for each mixing cycle, checking compatibility, green strength and moisture content. This enables the GSE program to regulate the amounts of water and additive added to obtain the compatibility and green strength the operator requires. The fewer reject castings due to problems with sand, fewer broken molds, better casting skin quality, these are the benefits of the Belloi & Romagnoli sand preparation cycle control system, which guarantees the delivery of high quality compactable, cohesive, permeable sand with constant characteristics over time.
The Belloi & Romagnoli BRAP6 Multi-press molding machine is a machine that produces green sand molds by means of a high-pressure process with multiple pistons operating at different pressures. The preloading hopper installed about two meters above the pattern pre-compacts the sand significantly through the effect of gravity giving a more uniform layer around the pattern. The Belloi & Romagnoli Multiple Pistons Head Molding System is designed to obtain constant hardness levels on all the molds horizontal and vertical surfaces, and around its edge. The pistons are operated by two separate hydraulic circuits, allowing two different pressures to be set. When the pressing cylinder brings the sand into contact with the molding heads the degree of compression of the sand under each individual head depends on sand height, sand compatibility, and the pressure applied. When the sand is compacted to a degree which allows it to withstand the pressure applied by the head the piston starts to retract. The difference in sand response around the sides of the mold is compensated by varying the pressure values of the internal pistons and supplying the ones around the perimeter with specific pressures.
Once all the heads have been activated and have reached their final positions, the compression cylinder continues its stroke to ensure that the mold hardness and sand cohesion are as uniform as possible. In the final compacting phase, the multi-press presses the mold from above and/or below. Thanks to the combined action of the two hydraulic control circuits. Naturally, the settings for this phase can be modified to obtain the hardness required. Production of castings with high dimensional precision, castings with excellent surface finishes and constant weight with no defects. This is what Belloi & Romagnoli Molding Line Molding System can be counted on to do with low operating costs and outstanding production quality." Translation from the video.
For more information, contact Greensand Controls ph +1.920.446.2468 email@example.com
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