GB2107373A

GB2107373A - Sucker rods

Info

Publication number: GB2107373A
Application number: GB08126708A
Authority: GB
Inventors: Kotaro Tsukamoto
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-09-03
Filing date: 1981-09-03
Publication date: 1983-04-27

Abstract

This invention relates to a sucker rod for use when drawing-up petroleum from underground sources. In more detail, a sucker rod according to the invention comprises a rod member 1 and two connector members 2 which are secured by welding, e.g. friction welding, to opposite ends of said rod member so as to permit interconnection of a plurality of the rod members. <IMAGE>

Description

SPECIFICATION Sucker rod This invention relates to a sucker rod for use when drawing-up petroleum from underground sources.

Known sucker rods may have a unit length of 25 feet and are made from a single rod of metal which is forged to provide upset or bulging portions in the region of each end. The upset portions are threaded so that a plurality of rods may be interconnected using pin or box type connector portions. In use, several hundred rods may be connected to each other. However, since the bulging portions of con ventional sucker rods are individually threaded, they are not suitable for mass production in that a considerable time is required to manufacture each sucker rod as a unit with a consequent high production cost. In addition, known sucker rods are not sufficiently versatile to meet the requirements of the customers.

It is therefore an object of the present invention to provide a sucker rod in which the rod portion and connector portions are separately produced and subsequently combined into one unit for ease of manufacture, better suitability for mass production and reduction in manufacturing cost, with substantial elimination of disadvantages inherent in the conventional sucker rods.

Thus, a sucker rod in accordance with the present invention comprises a rod member having a connector member welded to each end thereof whereby a number of rods may be connected together in end-to-end relationship.

The connector members are preferably friction welded to the rod. Such a technique, as mentioned hereinafter, facilitates alignment of the axes of symmetry of the rod and the connector members and simultaneously stabilises the material of rod and the connectors in the region of the welded joint.

Conveniently, the metallic material (metal or alloy) of the connector members possesses a higher strength, e.g. higher tensile strength than that of the rod member, thereby reducing the cost of material used in the manufacture of the sucker rod. If desired, the metallic material used for the rod member has a specific gravity less than that of the metallic material used for the connector members thereby reducing the overall weight of the sucker rod.

The invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 is an exploded perspective of a sucker rod according to one preferred embodiment of the present invention, and Figure 2 is a side elevational view of the sucker rod of Figure 1 as assembled into one unit.

In the drawings a sucker rod includes a straight rod member 1 of, for example, a circular cross section and two pin type end connector members 2.

The connector members are formed by forging and are thereby preliminarily processed for thread cutting. During manufacture, and whilst being rotated by a suitable rotating device (not shown), the connectors 2 are independently or simuitaneously brought into abutting contact with a corresponding end face of the rod portion 1 so as to frictionally weld together the metallic materials both for the connector 2 and rod portion 1. During the above processing, although a bulging larger in diameter than that of the rod portion 1 may be formed, such a bulging can readily be removed by a cutting machine (not shown), so that a smooth and hardly noticeable joint is obtained with an appearance similar two a sucker rod in which the rod portion and connectors are produced through one piece mouiding and the like.

Since the rod and connector members are separately produced, a number of different connector members can be produced, e.g. pin-pin type, pin-box type or box-box type and held in store until required so that, upon receipt of an order, sucker rods having the required end connector members can be rapidly produced on a large scale, with consequent reduction in the manufacturing unit price. Further, since the connectors are separately produced, the processing accuracy is highly improved, and thus, faulty items as in the conventional sucker rods in which undesirable bending is experienced upon connection into a long length, due to misalignment of the axes of the rod and connector portions, have been substantially eliminated giving improved reliability during use.

The purpose of employing sucker rods connected into long lengths is to draw up petroleum and the like through vertical movement of such connected rods, and therefore a metallic material having a high strength is required for the connector members so as to endure a large load to be applied to the threaded portions of the connectors, but such a high strength as described above is not required for the intermediate rod members.

Accodingly, it may be so arranged that a metallic material having a sufficient strength to withstand the above load is used for the connectors, while another metallic material having a strength to such an extent that will only endure the tension produced by the connection is employed for the rod members. It thus becomes possible to reduce the material cost as compared with that of the conventional one piece sucker rods. Furthermore, if the rod portions are composed of a metallic material having a small specific gravity, the sucker rod may be made light in weight as a whole end, therefore, output of a power source employed for the drawing up of petroleum and the like may be advantageously reduced.

Although, in the foregoing description, reference has been made to using friction welding process for fusing together the rod and connector members, owing to the easy alignment of the axes, and facilitation in welding between different kinds of metallic materials under a stable welded state, conventional welding methods may of course be employed.

1 .A sucker rod comprising a rod member and two connector members which are secured by welding to opposite ends of said rod member so as to permit interconnection of a plurality of the rod members.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Sucker rod This invention relates to a sucker rod for use when drawing-up petroleum from underground sources. Known sucker rods may have a unit length of 25 feet and are made from a single rod of metal which is forged to provide upset or bulging portions in the region of each end. The upset portions are threaded so that a plurality of rods may be interconnected using pin or box type connector portions. In use, several hundred rods may be connected to each other. However, since the bulging portions of con ventional sucker rods are individually threaded, they are not suitable for mass production in that a considerable time is required to manufacture each sucker rod as a unit with a consequent high production cost. In addition, known sucker rods are not sufficiently versatile to meet the requirements of the customers. It is therefore an object of the present invention to provide a sucker rod in which the rod portion and connector portions are separately produced and subsequently combined into one unit for ease of manufacture, better suitability for mass production and reduction in manufacturing cost, with substantial elimination of disadvantages inherent in the conventional sucker rods. Thus, a sucker rod in accordance with the present invention comprises a rod member having a connector member welded to each end thereof whereby a number of rods may be connected together in end-to-end relationship. The connector members are preferably friction welded to the rod. Such a technique, as mentioned hereinafter, facilitates alignment of the axes of symmetry of the rod and the connector members and simultaneously stabilises the material of rod and the connectors in the region of the welded joint. Conveniently, the metallic material (metal or alloy) of the connector members possesses a higher strength, e.g. higher tensile strength than that of the rod member, thereby reducing the cost of material used in the manufacture of the sucker rod. If desired, the metallic material used for the rod member has a specific gravity less than that of the metallic material used for the connector members thereby reducing the overall weight of the sucker rod. The invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 is an exploded perspective of a sucker rod according to one preferred embodiment of the present invention, and Figure 2 is a side elevational view of the sucker rod of Figure 1 as assembled into one unit. In the drawings a sucker rod includes a straight rod member 1 of, for example, a circular cross section and two pin type end connector members 2. The connector members are formed by forging and are thereby preliminarily processed for thread cutting. During manufacture, and whilst being rotated by a suitable rotating device (not shown), the connectors 2 are independently or simuitaneously brought into abutting contact with a corresponding end face of the rod portion 1 so as to frictionally weld together the metallic materials both for the connector 2 and rod portion 1. During the above processing, although a bulging larger in diameter than that of the rod portion 1 may be formed, such a bulging can readily be removed by a cutting machine (not shown), so that a smooth and hardly noticeable joint is obtained with an appearance similar two a sucker rod in which the rod portion and connectors are produced through one piece mouiding and the like. Since the rod and connector members are separately produced, a number of different connector members can be produced, e.g. pin-pin type, pin-box type or box-box type and held in store until required so that, upon receipt of an order, sucker rods having the required end connector members can be rapidly produced on a large scale, with consequent reduction in the manufacturing unit price. Further, since the connectors are separately produced, the processing accuracy is highly improved, and thus, faulty items as in the conventional sucker rods in which undesirable bending is experienced upon connection into a long length, due to misalignment of the axes of the rod and connector portions, have been substantially eliminated giving improved reliability during use. The purpose of employing sucker rods connected into long lengths is to draw up petroleum and the like through vertical movement of such connected rods, and therefore a metallic material having a high strength is required for the connector members so as to endure a large load to be applied to the threaded portions of the connectors, but such a high strength as described above is not required for the intermediate rod members. Accodingly, it may be so arranged that a metallic material having a sufficient strength to withstand the above load is used for the connectors, while another metallic material having a strength to such an extent that will only endure the tension produced by the connection is employed for the rod members. It thus becomes possible to reduce the material cost as compared with that of the conventional one piece sucker rods. Furthermore, if the rod portions are composed of a metallic material having a small specific gravity, the sucker rod may be made light in weight as a whole end, therefore, output of a power source employed for the drawing up of petroleum and the like may be advantageously reduced. Although, in the foregoing description, reference has been made to using friction welding process for fusing together the rod and connector members, owing to the easy alignment of the axes, and facilitation in welding between different kinds of metallic materials under a stable welded state, conventional welding methods may of course be employed. CLAIMS

2. A sucker rod as claimed in Claim 1, wherein the rod and connector members are frictionally welded together.

3. A sucker rod as claimed in Claim 1 or Claim 2 wherein the or each connector member is made from a metallic material having a strength higher than that for rod member.

4. A sucker rod as claimed in any preceding claim, wherein the rod member is a metallic material having a specific gravity smaller than that for the connector members.