Vol. 15
July Issue
Year 2014

Cover Page

in Vol. 15 - July Issue - Year 2014
From Foundry To Shot-Blast Process

C_GR 45/33 ST for heavy foundry castings (up to 40 tons) treatment

C_GR 35/11 turning table machine for foundry castings treatment

Turbotecnica bridge crane shot-blasting machine BETA 25000 GR 35/42 for heavy valves treatment

BETA 25000 GR 35/42 bridge crane machine for heavy valves treatment

Having increased ability in solving blasting issues and satisfied the most tortuous requests proposed by customers, Turbotecnica has developed skills in designing different applications in several fields of the shot blasting universe. Having been recently studying different shot blasting systems dealing with very high weight parts to treat, especially in the foundry field, Turbotecnica has headed over to the eastern countries, where important companies are placed. Huge castings weighing from 25 up to 40 tons are present a great challenge to struggle against. Several factors get into the game playing a very important role for a great success in the final result. Using very thick and resistant materials matched to the great experience of the technical department is the basis to sustain the work of the entire structure. Turbotecnica has been proposing many applications for this kind of customer's foundry requests in order to satisfy every aspect and get over any problem that may occur during the project. Of course, each client has his own necessity and has to deal with many aspects of the activity that is working with, starting with the physical conformation of the workplace till the whole aspect of the proper shot blasting process that is going to hit the casting is assessed. One of the toughest applications for casting treating they have faced is the continuous rail shot blast system CGR 45/33, which has to do with the treatment of huge and heavy casted valves. Due to the impossibility to handle the casting properly, they avoided those applications where handling of the pieces with cranes or rolls system is involved. Turbotecnica went instead towards a moving turning table application capable of carrying up to 40 tons, sliding on proper railways through a shot-blasting chamber equipped with six TC 380 EVO turbines mounted on the sidewall and on the roof of the blast chamber with an installed drive power of 22Kw each. The entire machine is divided into three sections: inlet and outlet railways and the actual blast chamber with inner dimensions of 5 (W) x 4.5 (H) x 7 (L). The parts are placed on the turntable by the existing bridge crane, next, the table goes through its own ride while rotating so that the materials are blasted from every angle. For optimum wear protection, the blast chamber is fabricated from manganese steel and overlapping manganese wear plates in the turbines shot projection area, while in the entry and exit area, abrasion-resistant rubber is mounted and easy to exchange. Three large hoppers are placed in the foundation pit in order to collect the blast media thrown by the turbines; consecutively, the media is transferred to the transport system of the media cleaning and classification unit. Maintenance is possible all over the machine through a three-storey platform that allows quick and easy access to all equipment sections requiring regular maintenance work. Despite the size and complexity of the system, they have been able to design it in the simplest possible way granting the highest efficiency for this type of machines. Other similar applications have been made by Turbotecnica especially in Europe having features close to the CGR 45/33; they are talking about the CGR 35/11 having a much smaller loading capacity (10 tons) than the big sister. As a machine built for moderate weight, the general composition of the 35/11 is quite the same as that of the 45/33 except for a few things. The turning table moves on rails and gets in and out only through one main door placed in front of the machine having dimension of 4(W) x 2 (H). The whole system is suspended from the ground allowing a screw conveyor to pass underneath the machine. Operators can access the blast room and rail zone stepping on the lateral pedestrian area. The blast room is equipped with lights to allow operators to check the pieces after the treatment. All the pedestrian area is surrounded by a handrail to secure people while doing maintenance, while operations are possible even on the roof of the shot-blasting machine only with the proper harness. This is a possible solution for the treatment of casting materials with low weight capacity and complete easy handling of the entire system so that any operator can get use of the system with no complication and in total safety. There are many possible applications regarding the foundry shot-blasting machines instead of movable turning tables, for instance, handling by crane is a great solution that Turbotecnica has developed with heavyweight-casted materials. Another challenge for their engineers was handling heavy casted valves with a crane and not with a high load capacity this time. It is one of the largest machines of this kind they have ever built, and has a load capacity bridge crane able to carry up to 25 tons. The BETA 25000 GR 35/42 ST is suited to descale big heavy casted valves from 2" to 72" made of different materials applied in the petrochemical sector. Due to the conformation of the pieces to treat, Turbotecnica faced the problem of what kind of handling system the machine should have been integrated for. For the best blast outcome, after getting a whole idea of the material shape, they opted to apply a bridge crane solution that allows a complete coverage of the blast media on the piece, going deeply into the structure of the casting. Another consideration they had in order to choose this application is the simple fact that these valves are easily transportable using chains to be subsequently connected to the bridge crane. Since the machine had to be placed into the foundry establishment, Turbotecnica had to adapt to some of the customer's applications, like the filtering system, that has been adjusted to their shot-blasting machine. Most of these kinds of installations have a special cleaning and classification unit, with the addition of a vibrating screen under the machine, where the blast media is transferred from the hoppers above. The grit thrown by the turbines, after the descaling process, causes a lot of waste material coming from the pieces that goes in the selection process. This is one of the main features that distinguishes blast machines working with castings from the others: they have to deal with big dirty parts coming from the objects and make sure that will not cause problems during the cleaning process. Like the vibrating screen, another element is to be considered very important in the cleaning process, and that is the magnetic separator, the second step in the cleaning process, but of primary relevance. It has the task of dividing the blast media from the waste material through a system of rotating magnetic rolls. The grit coming from the elevator passes through these rolls and gets caught from the magnetic part going then in the area where it will be recycled. The waste part to be deleted is therefore conveyed to the proper slide and collected in a proper bin. Falling down, the cleaned blast media is ready to feed the turbines and treat the pieces again in a continuous cycle. In the foundry sector, the cleaning units are a part to be considered with extreme care, because, if not well selected, the abrasive blended with the waste materials can damage not only the pieces to treat, but more importantly, the entire blast system, damaging progressively every transport and cleaning unit. In the BETA 25000, the separator unit can feed 5 turbines placed on one side wall of the blast chamber with an installed drive power of 22 Kw each. The blast chamber has inner dimensions of 4.5(W) x 5(H) x 6(L) and is internally covered with highly resistant anti-abrasive materials that are manganese plates and rubbers easy to change for maintenance processes. The blast media thrown by the turbines is collected in two large hoppers placed in the foundation pit from where the media is transported through a screw conveyor to the vibrating screen where the final sieving is done, keeping the biggest waste parts that comes directly from the treated castings, and expelled directly through a little lateral slide. A big platform is mounted by the separator unit to guarantee easy access to all the equipment requiring regular maintenance work. For sure, all these kinds of installations reduce time of work compared to the old systems where many operators were involved, and several hours were taken to treat a single piece. Nowadays Turbotecnica can count on many automatic systems that can be applied to the machines, decreasing working times in a very considerable way.

Author: Loris Pezzoni
For Information:
Turbotecnica SpA
via Macchiavelli 19/21
20025 Legnano (MI), Italy
Tel. +39.0331.576744-47
Fax +39.0331.576745
E-mail: info@turbotecnica.it