US1485249A - Underreamer - Google Patents

Description

Feb.26,1924. 1,485,249 G. H. CRAIG Y UNDERREAMER Filed Nov. 21.11921 Patented Feb. 26, 1924.

STTES 1,485,249 PATENT oFFlcE.

GROVER HARRIS CRAIG, OF HOUMA, LOUISIANA, ASSIGNOR OF ONE-HALF TO JOSEPH E. THATCHER, F HOUMA, LOUISIANA.

UNDERREAMER. z

To all whom t may concern.'

Be it known that I, GROVER H. CRAIG, a citizen of the United States, and resident of Houma, in the parish of Terrebonne and State of Louisiana, have invented certain new and useful Improvements in Underreamers, of which the following is a speciication.

This invention relates to underreamers especially adapted for use in connection with rotary drilling rigs.

An important object of this invention is to provide an underreamer having novel means whereby the bits of the same are automatically expanded when the underreamer leaves the lower end of the casing.

A further object is to provide simple means whereby the expansible bits of the underreamer are permitted to contract when it is desired to withdraw the underreamer.

A further object is to provide an underreamer which is simple to operate, of highly simplified construction and cheap to manufacture.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawing forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a vertical sectional view through the improved reamer.

Figure 2 is an end elevation of the same,

Figure 3 is a horizontal sectional view taken on line 3 3 of Figure 1.

Figure 4 is a perspective of a bit embodied in the invention.

In the drawing, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 5 designates a cylindrical body, the said body having its forward portion reduced slightly and interiorly screw threaded as indicated at 6 for engagement with a drill bit of any desiredl construction. The rear portion of the body 5 is interiorly screw threaded as indicated at 7 for engagement with the forward end of the drill stem by means of which an underreamer may be operated.

As illustrated in Figures 1 and 2 the body 5 is provided intermediate its ends with longitudinally extending recesses 8 which receive underreaming bits 9. The underreaming bits 9 have their rear por bits Application and November 21, 1921. serial No. 516,701.

tions provided with elongated slots 10 receiving pivot pins 11 whichy form a means for pivotally supporting the underreaming and for connecting the bits to the body. The underreaming bits 9 are urged to their operative position by means of leaf springs 12 having their forward portions in engagement with the inner edges of the bits and their rear or upper portions secured to the bottom wall of 'the recesses 8 by means of cap screws 13 or otherV suitable fastening devices. The bits 9 of which there are three are also urged to their operative positions by means of coiled springs 14 confined between the inner walls of the recesses 8 and the inner sides of the leaf springs 12. It will be seen that when the underreaming bits 9 are releasedl from engagement with the casing, the same will immediately swing to their outer positions by reason of the tension of the springs 12 and 14.

The forward portions of the underreaming bits 9 are provided with laterally projecting pins 16 received vin L-shaped grooves or 'slots having branches 17 and 18 arranged at right angles to each other. The branches 17 extend at right angles to the longitudinal axisY of the body and when the pins 16 arereceived within the branches the bits are in their inoperative positions.

However, when the bits enter the pairs of branches 18 the bits are in their operative positions and provide a hole large enough to receive the well casing.

The branches 18 of the L-shaped grooves in the side walls of the recesses have their upper portions extended laterally as indicated at 20 to permit of the removal or insertion of the pins 16.

In operation the underreamer is introduced into the well casing with the bits 9 in their inner or inoperative position. When the underreamer body passes out through the lower end of the well casing the bits 9 move outwardly and the laterally projecting pins 16 pass upwardly in the branches 18 of the L-shaped grooves. It will be seen that the pins 16 contact with the inner walls of the branches 18 and thereby positively prevent an inward movement of the expansible bits 9. When it is desired to withdraw the underreamer, it is merely necessary to pull the stem upwardly and the engagement of the outer edges of the expansible bits 9 with the lower end of the casing will force the pins downwardly into the inner branches 17 whereby the expansible bits are caused to assume their inoperative positions. The expansible bits 9 of which there are three are termed intermediate their ends with bends which deiine shoulders 2O which engage the forward end of the casing and thereby cause the entire expansible bits to move downwardly and inwardly to their inoperative positions.

With reference to the foregoing description taken in connection with the accompanying drawing it will be seen that an underreamer constructed in accordance with this invention may be readily and conveniently introduced into a well for the purpose of enlarging the hole formed by the main bit at the forward end of the underreamer. The flow of water is passed through a centrally arranged opening 22 in the body 5 and through diagonally extending branches 23, the said branches 23 forming a means tor supplying the eXpa-nsible bits 9.

Having thus described the invention, what fis claimed is l. An underreamer comprising a body havinga longitudinally extending recess, a bit freely received in said recess and having an elongated slot, a pivot pin extending through said slot and slidably and pivotally connecting the bit to the body, and spring means to urge the bit outwardly, there being a pin and slot connection between the lower portion of the bit and the body.

2. An underreamer comprising a body having a series of longitudinally extending recesses, bits received in said recesses and having elongated slots, pivot pins extending through said slot-s and supporting said bits, siiirings urging said bits outwardly, the walls ot said recesses being formed with L- shaped grooves having branches, and pins carried by said bits and slidable in said branches.

3,4451 underreamer comprising abody having a series .ot longitudinally extending recesses, bits received in said recesses and having slots, pivot pins extending` through said slots and supporting said bits, springs urging said bits outwardly, the walls of said recesses beine fo `ined with L-shaped grooves having branches, pins carried by said bits and slidable in said branches, the upper portions of the upper branches ot said L- shaped grooves being provided with lateral extensions forming passages for said pins.

4. An underreamer comprising a body having recesses, bits received in said recesses and having slots, pins extending through said slots and pivotally and slidably connecting the bits to the body, lea springs secured to the inner walls of said recesses and engaging the intermediate p0rtions of said bits, coiled springs confined between the inner walls ot said recesses and the inner edges of said bits and cooperating with said lea-i.z springs in urging the bits outwardly, the walls of said recesses being provided with L-shaped grooves having branches extending longitudinally of and at right angles to the axis of the body, and pins carried by said bits and slidable in said branches, the longitudinally extending branches of said grooves terminating in lateral passages.

GROVER HARRIS CRAIG,

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