FASTENING ELEMENT FOR POLYMER PARTS OF A CENTRIFUGAL PUMP

Abstract

This utility model relates to pump engineering, specifically to the design of fastening assemblies for the flow-through components of a centrifugal pump designed for pumping chemically aggressive liquids and manufactured from various polymeric materials resistant to the pumped medium, such as plastics. The utility model aims to develop a fastening element for polymeric components of a centrifugal pump for pumping chemically aggressive liquids in single-unit production environments without the use of complex technologies requiring expensive pre-production, such as the design and manufacture of foundry and other tooling, the development of casting or extrusion technologies, etc.This is achieved by using a special fastening element, which itself and the place where it is installed in the polymer part are manufactured mechanically, and the resulting connection of the fastening element with the polymer part is not inferior in its reliability to the connection of the said fastening element with the mating metal part.

Description

[0001] The utility model relates to pump engineering, namely to the design of fastening units for elements of the flow part of a centrifugal pump intended for pumping chemically aggressive liquids and manufactured from various polymeric materials resistant to the pumped medium, such as plastics.

[0002] A centrifugal pump housing is known in which the holes for the threaded fastening parts are made in embedded steel elements installed in the housing during its casting (RU 195 238 U1, published 01 / 17 / 2020).

[0003] A known embedded sleeve is used for embedding into a concrete structure element during casting (RU 2 523 707 C2, 20.07.2014).

[0004] The disadvantage of the proposed solutions is that the embedded elements are installed into the part during pouring, i.e. these solutions are only feasible using casting technologies with the additional complication of the embedded element positioning element.

[0005] The objective of the present invention is to develop a metal fastening element for polymer parts of a centrifugal pump for pumping chemically aggressive liquids in single-piece production conditions without the use of complex technologies that require expensive production preparation, in particular, the design and manufacture of foundry and other equipment, the development of pouring or extrusion technology, etc., which are installed in a threaded hole made in the part itself.

[0006] This is achieved by using a special fastening element, which itself and the place where it is installed in the polymer part are manufactured mechanically, and the resulting connection of the fastening element with the polymer part is not inferior in its reliability to the connection of the said fastening element with the mating metal part.

[0007] Fig. 1 shows a fastening element with a thread 1 on the outer diameter, a thread 2 on the inner diameter and elements 3 for screwing (unscrewing) into a polymer part.

[0008] Due to the fact that the strength of polymers can be an order of magnitude lower than the strength of steel typically used for parts of the pump's supporting structure, the geometric dimensions of the fastening element are selected in such a way as to compensate for this discrepancy and ensure that the polymer part can be installed in the pump using the fastening element according to its strength characteristics, just like a metal one.

[0009] To ensure that the connection between the polymer part and the fastening element corresponds to the metal connection between the fastening element and the mating part, it is necessary that the ratio of the squares of the outer and inner diameters of the fastening element be within the range of 5 to 50.

[0010] To ensure the reliability of the connection between the polymer part and the fastening element, it is necessary that the ratio of the outer diameter of the fastening element to its length is no more than 1.5, the ratio of the number of turns on the outer diameter of the element to the value of this diameter must be no less than 0.3, and the depth of the thread profile on the outer diameter must be no less than 1 mm.

[0011] For ease of installation and removal of the fastening element, special grooves or holes 3 for tools are made on its end.

[0012] To prevent the polymer fastening element from unscrewing during pump assembly, the threads on its outer and inner surfaces are made in the same direction.

[0013] The essence of the utility model is explained by the drawing, where Fig. 1 shows a frontal projection and a longitudinal section of the fastening element and indicates threaded surfaces 1 and 2, as well as an opening 3 for using a tool when screwing in the element.

Claims

An element for fastening polymer parts of the flow part of a centrifugal pump for pumping chemically aggressive liquids, which is a metal sleeve installed in a polymer chemically resistant element of the flow part of the pump, to ensure connection with a mating mating part, characterized in that it is manufactured mechanically and contains an internal threaded hole for fastening the mating part so that the ratio of the outer diameter of the fastening element to its length is no more than 1.5, the ratio of the squares of the outer and inner diameters is in the range from 5 to 50, the ratio of the number of turns on the outer diameter of the element to the value of this diameter is not less than 0.3, and the depth of the thread profile on the outer diameter is not less than 1 mm, while the direction of the thread on the outer and inner surfaces is the same,holes are made on the outer end of the fastening element for using a tool when screwing the sleeve into the body of the polymer part.

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