FIELD OF APPLICATION

The present invention refers to centrifugal pumps, their manufacture and repair, in all existing types and uses of pumps. For the transfer of fluids and solids in fluids. (For example Petroleum (fuel oil), sea water, wastewater, solids , etc . ) .

BACKGROUND

Centrifugal pumps, either those of great flow as well as those of medium or small flow, are made of casting.

This feature presents a series of inconveniences inherent to castings. When a component, or a part of same breaks or deteriorates, all the set must be replaced. Repairs may be made but there are not wholly reliable. The welding of cast pieces, specially those of great size, is a task that requires specialized welders. It is a difficult process since in scrolls of great size, the casting may get cracked or broken when applying intense heat to localized areas.

The manufactured shape of the centrifugal pump makes that not the whole pump wears out in an even way. There are areas or parts that suffer more wear than others. This implies that the pump in general becomes non operative when its most weak component has worn out, yet having components less demanded still a useful life. If we focus on the aspect of wear by use, the weakest components are the rotor periphery and the scroll of the case. It is proved that the wear of components of a centrifugal pump reduces the performance of same due to the leaks of liquid between the greatest gaps.

At present, it may be estimated, for centrifugal pumps to extract sand that operate 24 hours a day, that the conventional rotor made of casting lasts approximately four months and a half, and that the case lasts approximately 18 months. (The example is provided only as a comparison) .

When the case is made of casting, the periphery of its central section is curved. The area of maximum speed of the fluid shall be a relatively small area when compared with the whole width of the central section.

SUMMARY OF THE INVENTION

A centrifugal pump is provided, which main components, rotor and scroll, are principally made of iron pieces. Each piece may be easily replaced. Each piece may provide a side, the one on the inner side is the scroll, a surface with greater resistance to abrasion or wear. Furthermore, a centrifugal pump is provided where the periphery of its central section is relatively flat. As well, a method to manufacture the centrifugal pump is provided, which consists of preparing a disassembly of the components of the centrifugal pump, rotor and scroll. These disassemblies will take place depending on where they are located in the pump already finished. The edges of the disassemblies may provide bevels for the welding. Once the pieces are being located in position, the joints are filled with the sufficient material of the required supply.

As well, a method to repair the centrifugal pump is provided, which consists of detecting the worn piece or pieces, removing them from their position by oxyacetylene torch, weld cutting or abrasive disk. To replace them by equivalent pieces which are welded in the appropriate positions .

OBJECTIVES OF THE INVENTION

An object of the invention is to provide the components of the centrifugal pump, mainly case and rotor, made of replaceable parts, with which both its manufacture as well as its repair would be facilitated.

Another object of the present invention is to provide a centrifugal pump which scroll may be protected with hard ceramics or metal plates of greater strength than the body of the scroll.

Another object of the present invention is to provide a method to manufacture both a scroll of a centrifugal pump as well as a rotor as from the welding of replaceable pieces .

Another object of the present invention is to provide a method to easily repair the worn pieces of the pump, filling them with welding, and using any existing method: hand welding, semiautomatic welding or with multiple cycles of electrodes, even of different material of supply.

DETAILED DESCRIPTION OF THE INVENTION

The scroll and the rotor of the centrifugal pump (1) of the present invention are made from pieces (2) which are welded among themselves. The material of origin is iron, laminated and of any type of alloy, in respect with the characteristics of the usage. Once welded, they may be subject to thermal hardening treatments.

The scroll has two sides (3) with the shape of a washer, being coplanar and separated by a distance of the width of the rotor. In a portion (4) of its periphery, the closure of said width is provided with replaceable pieces and is completed with the discharge pipe (5) . Sides may be flat or evidence an inclination opening towards their centre, which presents a central hole (6) . Preferably, a closing ring (7) completes the central hole. The central hole is sufficiently big to allow the entrance or removal of the pump rotor. Each side has the necessary elements to strongly fix the rotor control as well as the suction hood: peripheric reinforcement, holes for lock bolts, etc.

Sides may be made of a single piece or of portions of pieces (8) welded together to obtain the same shape.

The periphery (9) of the scroll is made from metal pieces welded together. They may be flat (10) or evidence a curvature (11) equal to that of the sides. In general, pieces are rectangular, one of said sides is welded to the laterals and the other sides are welded to another similar piece at a certain angle so as to accompany the outer circumference of the laterals. Preferably, the metal is iron .

The pieces may have edges (12) prepared to facilitate the weldings .

The pieces may also be made of two layers of a metal of different structural property, for example a stronger iron, of great resistance to wear, on the inner side and a commercially iron, as support of the stronger iron layer. The joint between the two layers may be made by welding, riveted or by adhesive epoxy-like.

Another embodiment provides a single metal piece, wherein one of its surfaces has been subjected to a process of cementation or nitriding, obtaining a side with high strength iron and the opposite side with the common and less expensive iron as support of the high strong layer.

The present invention also comprises a method to manufacture and repair centrifugal pumps.

The method to manufacture the centrifugal pump consists of preparing a disassembly of the components of the centrifugal pump, rotor and scroll. These disassemblies will take place depending on where they are located in the pump already finished. For example, the disassemblies of the laterals of the scroll may be triangular sectors with a main radius equal to that of the case, and a minor radius equal to that of the central hole. The edges of the disassemblies may provide bevels for the welding. The disassemblies of the periphery of the scroll are square or rectangular pieces, wherein one of the sides has the width of the periphery of the scroll. As in the case of other pieces, the edges may provide bevels to facilitate the welding. The pieces of the periphery of the scroll may evidence a curvature to accompany the curvature of said periphery. Once the pieces are being located in position, the joints are filled with the sufficient material of the required supply.

The method to repair the centrifugal pump consists in detecting the worn piece or pieces, removing them from their position by oxyacetylene torch, weld cutting or abrasive disk. To replace them by equivalent pieces which are welded in the appropriate positions.