Wall scratcher

2,968,352

Jan. 17, 1961

Filed Dec. 11, 1956

L. A. HENE

WALL SCRATCHER

Sheets-Sheet 1

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Jan. 17, 1961 l. _A. hene 2,968,352

WALL SCRATCHER Filed Dec. 11. 1956 2 Sheets-Sheet 2

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United States Patent Office

2,968,352

Patented Jan. 17, 1961

2,968,352

WALL SCRATCHER

Lennart A. Hene, South Gate, Calif., assignor to BorgWarner Corporation, Chicago, III., a corporation of Illinois

Filed Dec. 11,1956, Ser. No. 627,613

Claims. (Cl. 166—173)

The present invention relates to wall scratchers, and more particularly to a wall scratcher having improved and novel scratcher fingers and means for securing said fingers on the supporting collar.

In the treatment of oil wells, it frequently becomes necessary and/or desirable to scratch the surface of the borehole to remove mud cake that is deposited thereon during the circulation of drilling mud down through the drill pipe or casing and up through the annular space between the casing and the borehole. Such scratching, or removing of the cake, is particularly desirable prior to cementing a casing or liner string in place in the borehole.

Heretofore, scratchers have been provided for this purpose, such scratchers generally comprising a supporting collar adapted to encircle a string of tubing or pipe with a plurality of scratcher fingers radiating from the collar for engagement with the surrounding bore hole for scratching the surface of the latter.

A principal object of the present invention is to provide an improved scratcher of the aforesaid general type having a sectional collar adapted to encircle a tube or pipe and having improved means for supporting on the collar a plurality of flexible scratcher fingers.

Another object is to provide a scratcher device of this type having improved scratcher fingers formed of wire bundles enclosed and encased by a coiled spring with the ends of the wires of the bundles projecting from the coiled springs, thus providing a multiplicity of scratcher elements on each scratching finger, somewhat in the nature of a crow’s foot.

A further object is to provide means for securing flexible scratcher fingers on a supporting collar or collar section, including a generally T-shaped element adapted to lie against the outer periphery of the collar with a flexible scratcher element folded about the stem of the T so as to be substantially U-shaped, with the sides of the scratcher element extending along the T-stem into overlying engagement with the T-head, whereby the T-head will cause the arms of the scratcher element to flex outwardly with respect to the collar for scratching engagement with the walls of a bore hole.

Still another object is to provide a structure in accordance with the last preceding object wherein the collar is lanced or slit to receive the T-member and the Ushaped scratcher element with alternate ribs between the lances respectively overlying and underlying the T-stem and the contiguous portion of the scratcher element, whereby certain ribs may be indented to securely clamp the T-member. In addition, a scratcher member-securing tab is also preferably struck or stamped out of the collar and bent over the base of the U-shaped scratcher to securely retain the same in place and against displacement.

Other objects and advantages will be herein described or will be apparent to those skilled in the art, and the novel features of the invention will be defined in the appended claims.

In the drawings:

Figure 1 is a view showing the wall scratcher hereof in top plan, as mounted upon a section of pipe or casing which is shown in section;

Figure 2 is a view in side elevation showing the wall scratcher mounted upon a section of pipe or casing and showing the improved scratcher-finger mounting means hereof;

Figure 3 is an enlarged view in section as taken on the line 3—3 of Figure 2;

Figure 4 is a fragmentary view in section as taken on the line 4—4 of Figure 3; and

Figure 5 is a view in perspective of the T-shaped member utilized in the scratcher finger securing means.

Like reference characters in the several figures of the drawings and in the following detailed description designate corresponding parts.

Referring to Figures 1 and 2 of the drawings, the wall scratcher hereof comprises a cylindrical supporting collar 1, which preferably composed of a pair of similar halfsections 2 and 3. The half-sections 2 and 3 are preferably detachably interconnected so that the collar may be easily mounted upon a pipe or casing generally designated 4. In the illustrative embodiment, the collar sections 2 and 3 are shown as having cooperatively interlocked overlapping flanges on their respective ends, although other specific means may be availed of for interconnecting the half-sections together as may be desired.

In a plurality of circumferentially-spaced positions about the collar 1, it is lanced or slit so as to provide a plurality of alternate outstanding ribs 5, which are spaced outwardly with relation to a suitable number of intervening ribs 6, thus providing a channel or socket.

Interposed in the space between the ribs 5 and 6 is a generally T-shaped element 7, having stem 8, lying between ribs 5 and 6, and a head 9, which serves a function hereinafter to be described in detail.

At the junction of the T-stem 8 with the T-head 9, the upper surface of the T-element 7, is provided with a generally rectangular projection 10, which provides a shoulder 11, engageable with one of the ribs 5, so as to properly position the T-shaped element 7 between the ribs 5 and 6 when the stem 8 is inserted therebetween.

Also disposed between the ribs 5 and 6 is the base, or supporting portion, of a flexible scratcher element generally designated 12. The scratcher element 12 preferably comprises a bundle or group of individual, relatively thin, wires 13, which are encased in a coil spring 14, but which project from the coiled spring at their free ends as at 15.

The scratcher element 12, about at its mid-point, is folded back upon itself so as to be generally U-shaped with its arms extending along the respective opposite sides of the stem 8 of the T-shaped member 7. At the points where the arms of the scratcher element 12 contact the T-head 9, the T-head 9 causes the scratcher element arms to flex outwardly so that they will project into engagement with the walls of a bore hole. The aforesaid enlargement 10 on the T-head also constitutes a spacer between the arms of the scratcher element 12 so as to maintain them in operative spaced relation. As is best shown in Figures 1 and 2, the scratcher elements 12 and their respective T-members 7 are preferably disposed at an angle with relation to the axis of the collar 1 and the pipe or casing 4.

In order to firmly secure the T-shaped member 7 and the scratcher element 12 in place between tbe ribs 5 and 6, the ribs 5 are preferably punched inwardly or indented as at 17 into engagement with the stem 8 of the T-s^saped member 7. which is preferably composed of a flexible material such as rubber, neoprene, or the like,

2,968,352 so that the stem 8 will be more or less compressed as is clearly shown in Figure 3. Pressure on the stem 8 will deform the flexible material and cause it to flow into the spaces at opposite sides of each rib 6 as at 18. In addition, the flexible material of the stem 8 will bulge out- 5 wardly as at 19 into the space between ribs 5. Thus the T-shaped element 7 is securely locked in place.

In order to aid in securing the scratcher element 12 in position, a tab 20 is preferably punched or struck out of the collar and bent over the base of the scratcher ele- 10 ment 12 with the free end of the tab 20 disposed within the arcuate end of the scratcher element 12 as is best seen in Figure 3. During operation, the pipe or casing 4 will be subjected to vertical movement in the bore hole of a well, and the ends 15 of the scratcher elements 12 15 will scratch the surface of the bore hole to remove mud cake or other deposits therefrom. In order to enhance the scratching action of the ends 15, the free ends of the wires 13 are preferably spread out to some extent so as to in effect provide crow’s feet at the ends of each 20 of the scratcher elements 12.

During such scratching action, the arms of the scratcher elements may be displaced from the head 9 of the T-shaped member 7, but their natural tendency is to assume their original position as illustrated. In order 25 to assist the arms of the scratchers 12 to re-assume their original positions, the opposite ends of the T-heads 9 are preferably bevelled so that the scratcher element arms will cam up on the bevelled ends.

In addition, when the T-shaped element 7 are com- 30 posed of a material such as rubber, or neoprene, or the like, the pressure of the arms of the scratcher elements 12 upon the T-head 9 will depress seats 21 in the outer faces of the T-head 9, these seats serving to partially retain the flexible arms in position during use of the scratcher. It should be understood, however, that if desired, the T-shaped elements 7 may be composed of material or materials other than resilient ones, but most effective locking of the T elements 7 in position may be effected when the T elements are composed of resilient material.

In view of the foregoing, it will now be apparent that I have provided an improved wall scratcher device wherein the flexible scratcher fingers are firmly and easily secured in an operative position upon the supporting collar without resorting to the use of screws or other fasteners which might tend to break or loosen during use of the scratcher. Furthermore, the mounting means for the scratcher fingers eliminates any abrupt corners against which the flexible fingers may be bent and caused to break due to concentrated stress.

While the specific details of the invention have been herein shown and described, changes and alterations may be resorted to without departing from the spirit thereof as defined in the appended claims.