US1878578A - Guard for collapsible underreamers - Google Patents

Description

Sept. 20, 1932. CRUM 1,878,578

GUARD FOR COLLAPSIBLE UNDERREAMERS Original Filed Nov. 14, 1928 2 Sheets-Sheet 1 BY WMMMW A TTORNEY INVENTOR.- Eo/and Z. Cram Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE ROLAND R. CRUM, or wn r'rrnn, cALIronNIn, Assrenon, BY MESNE ASSIGNMENTS, 'ro J'QHN GRANT, or LOS ANGELES, CALIFORNIA GUARD FOR COLLAPSIBLE UNDEBREAMERS Application filed November 14, 1928, Serial No. 319,277. Renewed December 3, 1931.

This invention relates to collapsible underreamers and more especially to means for protecting the cutters from damage while in collapsed position and during passage through the well casing string.

Underreamers of the collapsible type having laterally projectable cutters are in many instances so disposed on the underreamer body as to ride along thewell casing while being lowered. The well casing string is thus subject to damage by cutting, but the cutters themselves are subject to greater damage due to wear and abrasion as a result of the frictional dragging contact with the well casing string. This causes dulling of the edges of the cutters making them less eflicient. r

The present invention contemplates means to guard and hold the cutters from contact with the casing string. It is the primary object of this invention to provide such means so mounted that upon rotation of the tool they will be displaced enabling the cutters to fully expand and perform their cutting function without interference.

These objects together with other objects and-corresponding accomplishments are obtained by means of the embodiments of my invention illustrated in the accompanying drawing, in which s Fig. 1 is an elevation of a complete underreamer with guards detached, the cutters beingin expanded posit-ion; Fig. 2 is an axialsection through the underreamer within acasing, the underreamer being in collapsed position and the guards mounted thereon; Fig. 3 is an axial seotionsnowing the cutters below a casing and in expanded position, the guards having been displaced; Fig. 4 is a sectionas seen on the line 1- 1 of Fig. 2; Fig. 5 is a section as seen on the line 5-5 of Fig. 1, on an enlarged scale, the cutter spindle being shown in elevation and with a guard mounted thereon; and Fig. 6 is a perspective view of a guard.

Referring more particularly to the drawings, a body 7 has an upper pin adapting it' for connection to a drill string and at the bottom has a detachable box 8 to receive 50 the pin of a drilling tool or anyother Suitable device. Extending through the body is a circulation passage 9. Cutter accommo'dating cavities 10 are provided in the periphery of the body. These cavities have disposed therein cutterswhich'are projectable into expanded position and retractable into collapsed position. At the "upper ends of the cavities are pockets 11 to receive the upper ends of cutter spindles. Formed on thebody'and adjacent the pockets are inclined guide surfaces 12- for directing the spindles into the pockets. At the lower ends of the cavities are inclined bearing surfaces 13 for the spindles to bearagainst. Suitable vent holes are provided for the pockets to prevent trapping of circulation fluid therein, and courses connect with the circulation passage 9 to deliver wash water to the cutters and cavities.

There are four cavities shown herein, but there may be more or less, and in each cavity is mounted a cutter spindle 14. The cutter spindles are angled having knees 15 dividing each'spindle'into two. journal sections for roller cutters. The lower ends of the spindles have bearing surfaces 16 for engagement with the corresponding bearing surfaces 13 on the body. These spindles are of such length that they may be moved longitudinally and bear at their lower ends against the surfaces 13. In the upper positions of the spindles, the lower ends are moved a slight distance outwardly. The upper ends of the spindles are in the, form of fingers 17 which will snugly fit into the pockets 11. The ends of the fingers are inclined in a direction corresponding tothe guide surfaces 12 as indicated by 18. In collapsed position as shown in Fig. 2, the fingers are out of the pockets and their ends are engaged with the guide surfaces. In expanded position, the fingers, as shown in Fig. 3 are disposed in the pockets. Mounted upon the journal sections are rotative cutters 19 suitably held in position by end collars.

The box member 8 is secured to the lower end of the body and provides a shoulder upon which a compression spring 20 is mounted. Slidably mounted over the box is a follower 21 of sleeve form arranged to have the compression spring bear against Recesses 22 are formed by upstanding abutments on the follower so as to form seats or pockets for the lower ends of the spindles 14:. The follower and spring tends to move the spindles upwardly and outwardly.

The underreamer maybe collapsed by forcing the cutter mechanism downwardly so that the fingers 17 are out of their pockets and the inclined bases of the spindles rest against the guide surfaces 13 as shown in this position they are positively held against lateral movement with respect to the drilling axis of the underreamer.

It will be noted that without guards the cutters would ride againstthe casing when disposed therein. This results in the cutting edges of the rollers being dulled while being lowered with resultant decrease of efficiency. To overcome this, I have provided each knee 15 with a groove 23.. The upper and lower walls of the grooves are preferably parallel, and the outer faces of the knees are flat. A guard is provided for each knee comprising a wear portion 24 to cover the knee and hav ing a tongue 25 corresponding to the groove 23. The wear portion is of such thickness that when the guard is disposed in place upon its knee, the guard will extend laterally beyond the cutters and thereby hold them from contact with the wall of the casing. However, the ends of the grooves are open so that upon rotation of the tool, the guards will be enabled to move circumferentially in relation to the underreamer and be displaced, dropping to the bottom of the hole. Displacement is caused by expansion of-the cutters and engagement of the guard with the side of the hole. I

While a specific type of collapsible underreamer has been described herein, it will be understood that the invention is not limited to use with such species of underreamer. The specific type of underreamer has been described for illustrative purposes only.

The invention is adapted to be embodied in other species of underreamers and in its broad aspect is not limited to underreamers having roller cutters. The scopeof'the invention is apparent from the appended claims. l

What I claim is 2-.- I

1. The combination with a collapsible underreamer having a body and laterally projectable cutters, of guards projecting from the underreamer laterally beyond the cutters, said guards being mounted on'said underreamer. to be displaceable by rotational movement of said underreamer.

2. The combination with a collapsible underreamer having a body and laterallyprojectable cutters of guards mounted on i said cutters by tongue and groove connections open at the ends so that said guards may be displaced by rotational movement of said underreamer, said guards extending laterally beyond said cutters.

5. The combination with a collapsible underreamer having roller cutters mounted on spindles projectable laterally of said body, of guards mounted on said spindles and extending laterally beyond the cutters, said guards being mounted on said spindles to be displaceable by rotational movement of said underreamer. v

6. The combination with. a collapsible underreamer having roller cutters mounted on spindles projectable laterally of the body,

of guards mounted on said spindles by tongue and groove connectionsopen at the ends so as to be displaceable, saidguards extending laterally beyond said cutters.

7. The combination with a collapsible underreamer having cutters projectable laterally' of said body comprising angled spindles extending longitudinally of said a body, roller cutters journalled on said spindles, and guards mounted on the knees of said spindles so as to be displaceable by rotational fmovement of said underreamer.

8. The combination with a collapsible underreamer having abody with roller cutters projectable laterally of'jthe body comprising angled spindles extending longitudinally of the body, roller cuttersi'journalled thereon, and guards mounted on the lmees of said spindles by tongue and grooveconnections open at the ends so as to be displaceable, said guards extending laterally beyond said cutters. l

9. The combination with a collapsible underreamer having a body and laterally projectable cutters, of guards projecting from the underreamer laterally beyond the cutters, said guards being mounted on the underreamer to be displaoeable by frictional engagement with the side of the hole. 1 10. The combination with a collapsible underreamer having a body and laterally projectable cutters, of guards mounted on the w cutters and projecting outwardly laterally therefrom, said guards being mounted on the cutters to be displaceable with reference thereto by frictional engagement with the side of the hole.

In Witness that I claim the foregoing I have hereunto subscribed my name this 3rd day of November, 1928.

ROLAND R. CRUM.

Images