JPH04194190A - Drill tube - Google Patents

Abstract

PURPOSE: To manufacture inexpensive and easily available manufacturing facilities by performing the centrifugal casting of a plurality of tubes at a first stage and connecting the end parts of the tubes at the next stage for forming a drill tube with a required length. CONSTITUTION: First, a cylindrical permanent mold is rotated speedily, and an appropriate metal material is subjected to centrifugal casting, thus forming a tube 11 with a thick wall that becomes a main part 10 of a drill tube. Then, welding is made at a welded part 12 in the end part of each tube 11, the drill tube 10 with a required length is composed, and an end part member 13 where external thread is cut and an end part member 15 where internal thread is cut are welded by welded parts 14 and 16. Then, in the case of excavation, the end parts of the drill tube 10 are connected successively in an excavating device via the end part members 13 and 15, and an oil well, a bore hole, and the like are excavated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is made into a drill tube, connected end to end one after another, rotated and inserted into a drilling equipment, and drilled into an oil well, borehole, etc. It relates to a method of manufacturing a series of drill tubes of a type designed for drilling.

BACKGROUND OF THE INVENTION Drill tubes for such applications are normally manufactured by forming a seamless tube by a drilling process, but by rolling a flat sheet of steel into the shape of a tube and joining the butt longitudinal edges. It can also be manufactured by welding together to form a composite tube. In either case, it is necessary to provide a female thread and a male thread on both ends of the tube, which are used to connect the tubes together in the drilling equipment, and are inserted into the end of the tube and welded to it. be done.

SUMMARY OF THE INVENTION The main disadvantage of such tube-forming techniques is the high cost, which is primarily due to the relatively complex manufacturing techniques and associated equipment, and the This is because the number of is relatively small. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for producing drill tubes for use in excavation operations which is cheaper than by the previously described drilling and welding techniques and which allows the use of readily available manufacturing equipment. be. A problem with the conventional technology is that the drilling process requires expensive steel, and in particular the drilling technique requires refined round steel as a starting material.

(Means for Solving the Problems) According to the present invention, a method for manufacturing a drill tube for excavation work includes a step of centrifugally casting a plurality of tubes, and a step of connecting the ends of the tubes to each other to obtain a required length. forming a drill tube.

Centrifugal casting of tubes is generally less expensive than the previously described drilling and assembly techniques, and also utilizes more manufacturing equipment. Additionally, the present invention allows for the use of categorical keys, resulting in even greater cost savings. Additionally, because the invention relies on casting technology, the alloying composition of the steel can be varied to slow down the wear rate and thus extend the service life. Perforated tubes have limitations, especially when changing alloy compositions. The reason for this is that it is necessary to limit the alloy components that can be used in the drilling process. Tubes currently in use have a useful life of approximately three months, after which they are pulled from the borehole and transported to a factory, where the diameter is corrected through an expensive continuous welding process and worn material is removed. Needs to be replaced. The present invention allows the use of the correct, highly wear-resistant alloy, thus increasing the life of the tube. If this could significantly reduce costs, the worn tube could be discarded instead of having its diameter corrected.

The threaded end attachment to the tube can be such that the tool is attached to the end of the drill tube immediately when it is manufactured, or it can be attached later by the user of the drill tube. It should be noted that the end fittings can be made as part of the centrifugal casting operation and completed by suitable machining and threading techniques.

The invention further relates to a drill tube manufactured by the method described above, and a preferred embodiment of the invention will now be described with reference to the accompanying drawings.

(Embodiment) In a preferred embodiment, the main body portion 1 of the drill tube
0 is made up of a plurality of quay tubes 11. Each tube 11 is formed by centrifugal casting of a suitable metal material using a cylindrical permanent mold, which is rotated at high speeds as the molten metal is injected, thus causing it to burst onto the inner surface of the mold. The molded metal forms a hollow cylinder or tube of uniform wall thickness. It is believed that the tube formed in this manner has an outer surface of uniform particulates and therefore also contains fewer inclusions. Each tube 11 is welded together at its ends so that a weld 12 occurs between the ends and collectively forms a drill tube 10 of the required length.

To complete the drill tube for use in drilling, a conventional externally threaded end member 13 is welded to one end of the drill tube as shown at 14, and a conventional internally threaded end member 15 is welded to one end of the drill tube as shown at 14. is welded to the other end of the drill tube as shown at 16.

The end pieces 13 and 15 can be welded to the drill tube at the point of manufacture or can be connected separately later by the end user of the duplex.

Another possibility is to partially form the associated end piece as a specially centrifugally cast tube 110 section. This technique forms the associated end of the final drilled tube when the tube is centrifugally cast, and the end piece is finished by machining or threading using suitable equipment.

In the embodiment of the invention described above, a typical drill tube 11 is formed by four centrifugally cast tubes each 7.5 feet in length, the tubes having a length between their ends. When welded, the length is 9.
This results in 144 meters (9,144 feet) of drill tube.

The centrifugal casting of tube 11 should be controlled so that the wall thickness of each tube forming the drill tube is uniform. This wall thickness is intended to be within the range of wall thicknesses commonly used for conventional perforated seamless drill tubes and spliced drill tubes. The thickness depends on the type and depth of the drilling operation using the drill tube.

It is expected that if drill tubes were manufactured by the method of the present invention, the price of a regular length drill tube could be reduced to >A$8,500.00 (in 1990 dollars). The price of drill tubes manufactured by the prior art amounts to A$13,000.00.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a completed drill tube produced by the method of the present invention. 10... Drill tube, 11... Tube, 12
... Welded portion, 13... End member, 14... Welded portion, 15... End member.

Claims (5)

[Claims] (1) In the method for manufacturing a drill tube for excavation work,
A method comprising the steps of centrifugally casting a plurality of tubes and welding the ends of the tubes together to form a drill tube of a desired length. 2. The method of claim 1, wherein said threaded end fitting to a tube is subsequently coupled to an opposing end of a finished tube. (3) The threaded end fitting for the tube is partially formed during centrifugal casting of the tube forming the end of the drill tube and completed by suitable machining and threading operations. Method. (4) In the method for manufacturing a drill tube for excavation work,
A method substantially similar to that described above in the drawings. (5) A drill tube manufactured by the method described in any one of the preceding claims.