US3805463A

US3805463A - Drill mast back brace

Info

Publication number: US3805463A
Application number: US00332719A
Authority: US
Inventors: D Lang; W Weston
Original assignee: Bucyrus Erie Co
Current assignee: Caterpillar Global Mining LLC
Priority date: 1973-02-15
Filing date: 1973-02-15
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: JPS5442321B2; GB1452341A; JPS49126105A

Abstract

A blast hole drill mast is pivotal between a horizontal position and an upright drilling position. Back bracing for the mast includes a pair of struts each of which extends from the drill frame to a point high on the mast and each of which folds at a knee to lie beneath the mast when it is lowered. A pair of knee braces pivotally connect near the foot of the mast and the free end of each slidably engages the knee of a strut. A locking mechanism on the end of each knee brace fastens to the strut to lock the back brace when the mast is fully erected. The locking mechanism is pneumatically releasable from the operator''s cab when the mast is to be lowered.

Description

m1 3,805,463 [451 Apr. 23, 1974 DRILL MAST BACK BRACE [75] Inventors: David M. Lang; Warren B. Weston,

both of South Milwaukee, Wis.

[73] Assignee: Bucyrus-Erie Company, South Milwaukee, Wis.

[22] Filed: Feb. 15, 1973 [21] Appl. No.: 332,719

[56] 1 References Cited.

UNITED STATES PATENTS 3,198,263 8/1965 Reischl 173/23 3,175,698

3/1965 Dassler 212/145.

3,205,627 9/1965 Gyongyosi 52/116 2,703,634 3/ 1955 Lee 254/l39.1 2,638,188 5/1953 Corn 52/149 Primary Examiner-Henry C. Sutherland Assistant Examiner-Mark H. Wolk Attorney, Agent, or Firm-Barry E. Sammons 57 7 ABSTRACT A blast hole drill mast is pivotal between a horizontal position and an upright drilling position. Back bracing for the mast includes a pair of struts each of which extends from the drill frame to a point high on the mast and each of which folds at a knee to lie beneath the mast when it is lowered. A pair of knee braces pivotally connect near the foot of the mast and the free end of each slidably engages the knee of a strut. A locking mechanism on the end of each knee brace fastens to the strut to lock the back brace when the mast is fully erected. The locking mechanism is pneumatically releasable from the operators cab when the mast is to be lowered.

11 Claims, 9 Drawing Figures PMEWEMPR 23 mm SHEH Kl M 5 DRILL MAST BACK BRACE BACKGROUNDOF THE INVENTION The field of the invention is collapsiblebraces for drill masts and more specifically, back braces for mobileblast hole drills such as that disclosed inU.S. Pat. No. 3,198,263, issu edtoK. E. Reischl on Aug. 3, 1965.

Blasthole drills are characterized by the speed with which they can drill large numbers of holes andthe ease with which they can be moved from onedrilling siteto another. In recent years many-of the setup and drilling procedureshavebeen automated. As illustrated jacks. Automatic leveling is accomplished by a system such asthat disclosed in U.S. Pat. No. 3,625,483 issued to Thomas Aisto'ner on -Dec. 7, 1971, and drilling is performed and automatically controlled by a system such as that disclosedin U.S. Pats. Nos. 3,581,830 and 3,613,805 issued on June 1, 1971 and-Oct. 19, 1971,

respectively.

After thedrill mastiserected, back bracing must be connected to provide support to the mast during-the drilling operation. As illustrated in US. Pat. No. 2,905,280issued onSept. 22, I959, suchback braces include struts which connect to the drill frame and extend upward toconnect 'to a point on the erect drill mast/Typically, when the mast is lowered, the struts are firstdisconnec'ted from the drill frame'by manually removing a pin, and the strutsalongwith otherbrac'ing members are then manuallyfolded againstthemast before it-islowered.Similarly, the bracing is manually reconnected whena newdrilling site is reached andthe mast is erected toa drilling position. This manualstep in the drilling procedure significantly increases the setup time and decreases drillingefficiency.

SUMMARY OF THE INVENTION The invention relates "to a back brace construction which automatically unfolds and lockswhen the drill mast is erected -to an upright position. More specifically, the back brace inc ludeszia strut having one end pivotally connected tothemast and the other end connected tothe drill frame, the strut also havingaknee intermediate itsends which provides a joint at which the strutfolds when the mast islowered; aknee brace having one endpivotallycon'nected to apoint adjacent the foot of themast and afree end'slidably retainedto the strut ata point whichis intermediate its ends; and a locking mechanism which is operable to fasten the knee brace to the strut when themastis-raised to an upright drilling position. To lowerthe mast, the locking mechanismisfirst released by actuating a cylinder from the operators cab. The mast is-then lowered and the strut folds at its knee and lies compactly beneath the inder. 'When'the mast reaches the desircddrilling position, the locking mechanism fastens the knee brace to the strut and to thereby form a rigid supporting structure.

Another object of the invention is to provide an automatic back brace which folds beneath the mast when it is lowered to a transport position. The back brace includes a minimal number of elements which fold into a compact traveling position beneath and beside the mast which does not increase the outer dimensions of the drilling rig.

Still another object of the invention is to provide an automatic back brace which will lock at a plurality of selected drilling angles. The strut is divided by the knee into upper and lower brace members and the lower brace member is constructed of two telescopically connected tubular members which are adjustable to alter the length of the strut when it is completely unfolded.

As a'result, the drilling angle of the mast is altered by selecting the appropriate length.

'A more specific object of the invention is to provide support for the drill'mast during drilling. When erected,

the upper brace member and lower brace member form a substantially straight, rigid strut which forms a triangular configuration with the drill frame and mast. The knee brace extends from the foot of the mast and locks the strut atits-knee to divide it into a pair of brace members capable of withstanding substantially higher axialloads. Also,'the mast is typically formed by a pair of spaced stanchions and rigidity is further improved by adding a second strut and associated knee brace which operatesinconjunction with the first in side-by-side relation.

The foregoing and other objects and advantages of the invention will appear from the following description. Inthe description reference is made to the accompartying drawings which form a part hereof, and which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, and reference is made to'the claims herein for interpretingthe breadth of the invention.

' BRIEFDESCRIPTION OF THE DRAWING FIG. 1 is an elevation view of a blast hole drill which incorporates the present invention,

. FIG. 2 is a partial end view of the drilling rig of FIG.

FIGS. 3-5 are partial views of the drilling rig of FIG. 1 showing the invented back brace in three successive positions,

FIG. 6 is a partial view with parts cut away of the knee and locking mechanism which form a part of the back brace,

' FIG. 7 is a view in cross section of the back brace knee of FIG. 6 taken on the plane 7-,7,

FIG. 8 is similar to FIG. 7, but shows the locking mechanismin an'unlocked position, and

FIG. 9 is an elevation view of theblast hole drill with the mast erected for angle drilling.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a blast hole drill includes a main frame '10 mounted on crawlers 11 suitable for transporting the drillfromone site to another. An operator's cab 12 is located on the left hand side of the main frame at its forward edge and a machinery housing 13 is located thereon and extends back to the rear edge of the main frame 10. A pair of mast supports 39 connect with and extend upward from the main frame 10 to the right of the operators cab, and the foot of a mast 14 pivotally connects thereto. The mast 14 is pivotal in a vertical plane between a horizontal transport position and an upright drilling position and is driven by a pair of hoisting cylinders 16 which connect between the main frame 10 and the mast 14. A drive unit 17 is slidably mounted for linear motion along the length of the mast 14 and it includes a rotary drive motor (not shown in the drawings) which couples with a drill string 18. For a more detailed description of the connection of the mast to the main frame, reference is made to the above cited US. Pat. No. 3,198,263 and for a more detailed description of the rotary drive and linear drive systems, reference is made to the above cited U.S. Pats. Nos. 3,613,805 and 3,581,830.

Referring to FIGS. 1 and 2, the mast 14 is comprised of a pair of spaced stanchions l9 and 19a connected together by a series of spaced cross pieces 55. The back brace connects to these stanchions and extendsdownward to connect with a pair of upright supports 20 and 20a which are positioned along the back edge of the machine and extend upward from the main frame 10 above the machinery housing 13. A cross piece 54 connects the upright supports 20 and 20a and a pair of rests 53 are formed thereon.

The back brace is comprised of two identical sections which connect the stanchion 19 to the rear support 20 and the stanchion 19a to the rear support 20a. Because the elements of these two sections are identical, they are identified hereinafter with like reference numbers, however, the suffix A is added to those elements of the right section. Although the description which follows makes reference only to the elements of the left hand section, it should be understood that the right hand section includes the same elements and they operate in identical fashion in conjunction with the left band section to provide additional support for the mast 14.

Referring to FIGS. 1 and 2, a strut is formed by an upper brace member 21 and a lower brace member 23. The upper brace member 21 is of tubular construction and has one end pivotally connected to an ear 22 on the stanchion 19. The ear 22 is welded to the stanchion 19 and is located approximately midway between its ends. The upper brace member 21 pivotally connects to the lower brace member 23 at a knee which is indicated generally at 25. The lower brace member 23 in turn rotatably connects to a set of ears 24 which are formed on the upright support 20. As shown more clearly in FIG. 6, the knee 25 is a knuckle joint which allows the strut to fold at its midpoint in a vertical plane. A cross member 26 which is tubular in shape connects the two sections of the back brace at their knees 25 and 25a. A support shaft 27 extends outward from the end of the cross member 26 completely through the knee 25 forming the linking member of the knee joint. The support shaft 27 extends beyond the knee 25 and a circular guide plate 28 welded to a cap 29 is connected to its end by a pin 30. The guide plate 28 is spaced outboard from the knee 25 to form a guideway indicated generally at 31.

As shown best in FIGS. 4 andS, the lower brace member 23 is comprised of a tubular section 32 which connects with the knee 25 and an inner section 33' which connects with the upright support 20. The inner section 33 is slidably connected for telescopic motion within the outer section 32 and it includes a plurality of transverse openings 34 spaced along its length. A transverse opening 35 is also formed through the lower end of the outer section 32 and a pin (not shown in the drawings) is inserted through the opening 35 and a selected one of the openings 34 to fix the total length of the lower brace member 23. As will become apparent from the description which follows, by so adjusting the length of the lower brace member 23, the mast may be set at any one of a number of drilling angles ranging from vertical, to 30 off vertical in increments of 5.

Each strut of the back brace is supported by a knee brace 38 which extends upward from the main frame 10 to the knee 25. A plate 40 is welded to the mast support 39 and a pivotal connection 41 is made between it and the lower end of the knee brace 38. The knee brace 38 is thus connected adjacent the foot of the mast 14 for pivotal motion in a vertical plane with the

brace members

21 and 23. The free end of the knee brace 38 rides in the guideway 31 at the knee 25 and is held in slidable engagement therewith by the guide plate 28 and support shaft 27. As illustrated in FIGS. 3-5, the knee 25 freely slides along the length of the knee brace 38 when the mast is raised and lowered.

A locking mechanism indicated generally at 42 is formed on the free end of the knee brace 38. The locking mechanism 42 includes a pair of closely spaced steel plates 43 which are welded to the end of the tubular knee brace 38 and are formed in a hook shape to provide a downward facing recess 44 which receives the support shaft 27. The outer leg of each hook shaped plate 43 is extended to form a stop 45. The locking mechanism 42 also includes a pneumatic cylinder 46 which is fastened by means of bolts 47 to the top edge of the plates 43. Its rod 48 extends between the plates 43 into the recess 44 and is oriented in a direction substantially perpendicular to that of the knee brace 38. A bar 49 is attached to the end of the rod 48 and as shown in FIG. 7, when fully retracted the bar 49 is withdrawn above the recess 44. However, as shown in FIG. 8, when the rod 48 is extended the bar 49 bears against the support shaft 27 in the recess 44 and the knee brace 38 is lifted in the direction indicated by the arrow- 51. Thus, when the bar 49 is retracted, the support shaft 27 is received in the recess 44 and locked to the knee brace 38, and when the rod 48 is extended, the knee brace 38 is unlocked.

Referring to FIGS. 3-5, when the mast 14 is fully lowered to a transport position, the strut folds at the knee 25 and lies beneath the mast 14. A pair of pads 52 connect to a cross piece 55 on the mast l4 and are positioned to rest against the pads 53 supported by the frame 10. The knee brace 38 is in a nearly horizontal position during transit. When the mast 14 is raised by the hoist cylinders 16, the strut unfolds and its knee 25 moves upward and radially outward from the mast pivot point 15. As a result, the knee brace 38 is lifted and the support shaft 27 slides outward along its underside toward the locking mechanism 42. When the mast 14 is fully erected to a drilling position the support shaft 27 engages the stop 45 on the locking mechanism 42 and the knee brace 38 drops and locks with the strut. After drilling is completed the operator in the cab 12 actuates the pneumatic cylinder 46 and the knee brace 38 is unlocked from the strut. The hoisting cylinder 16 is then actuated to lower the mast l4 and the back brace folds into its compact transport position.

The above procedure is altered slightly when angle drilling is to be performed. The mast 14 is first erected to its vertical drilling position as shown in FIG. 5 and the inner and

outer sections

33 and 32 of the lower brace member 23 are then unfastened from one another. The mast 14 is lowered to the desired drilling angle as illustrated in FIG. 9, and the

sections

32 and 33 are refastened for drilling. The procedure is reversed after drilling is completed. The

sections

32 and 33 are unfastened, the mast 14 is raised to the vertical,

the

sections

32 and 33 are refastened, and the mast 14 is lowered to the transport position.

It should be apparent to those skilled in the art that a number of alterations can be made without departing from the spirit of the invention. For example, the lock- I ing mechanism may be carried by the strut rather than the knee brace, and the knee brace 38 need not connect at the juncture of the upper and lower brace members. Also, in the preferred embodiment of the invention the strut is relatively straight when fully erected and the knee brace 38 intersects at a-substantially right angle therewith to provide support at the midpoint of the strut. The back bracemembers thus form a pair of roughly identical triangular structures which add considerable rigidity to the mast 14 during drilling. Although this arrangement is particularly desirable, variations can be made such as shifting the knee from the midpoint of the strut or moving the connection of the knee brace to another convenient location adjacent the foot of the mast. Finally, instead of altering the length of the lower brace member .to' provide a selection of drilling angles, the length of the knee brace may be a1- tered, or the point at which it'locks with the strut may be altered.

We claim:

1. In a drill having a mast which is connected to a frame for pivotal motion between an upright drilling position and a transport position, a back brace comprising;

a struthaving one end connected to the mast, having its other end connected to the frame, and having a knee intermediate its ends which provides a joint at which the strut folds when the mast is lowered from its upright drilling position;

a knee brace having one end pivotally connected to a point adjacent the foot of the mast and having a free end which is slidably retained to the strut intermediate its ends; and

a locking mechanism associated with said strut and said knee brace, said locking mechanism being operable when said mast is raised to its upright drilling position to fasten said knee brace to said strut and to thereby lock said strut in an unfolded position.

2. The back brace as recited in claim 1 in which the knee brace is slidably retained to said strut at said knee, and said knee is located midway between the ends of said strut.

3. The back brace as recited in claim 1 in which a support shaft connects to said strut and said locking mechanism connects to the end of said knee brace, wherein said support shaft engages and fastens to said locking mechanism when said mast is raised to its upright drilling position.

4. The back brace as recited in claim 3 in which said locking mechanism includes a power actuated cylinder which is positioned to engage said support shaft when actuated and to thereby unfasten the strut from said knee brace.

5. In a drill having a mast which is connected to a frame for pivotal motion between an upright drilling position and a transport position, a back brace for supporting the mast during drilling which includes two sections each comprising:

an upper brace member having one end connected to said mast at a point intermediate the ends of the mast;

a lower brace member having one end pivotally connected to the other end of said upper brace member to form a knee and having its other end connected to the drill frame at a point which is substantially spaced from the foot of the mast;

a knee brace having one end pivotally connected to the frame at a point adjacent the foot of the mast and having its other end slidably retained to said knee; and

a locking mechanism associated with said knee brace and operable to fasten said knee brace to said knee when the mast is in its upright drilling position.

6. The back brace as recited in claim 5 in which said sections are fastened together by a cross member which connects their knees.

7. The back brace as recited in claim 6 in which a support shaft extends from each end of said cross member and each support shaft connects to the knee of one of said sections and slidably engages the knee brace of that section.

8. The back brace as recited in claim 7 in which each locking mechanism includes a hook shaped plate connected to the end of its associated knee brace and each engages and locks with its associated support shaft when said mast is in its upright drilling position.

9. The back brace as recited in claim 8 in which each locking mechanism includes power actuated means for unlocking its hook shaped plate and associated support shaft. 7

10. The back brace as recited in claim 5 in which the length of said lower brace member is adjustable to provide support for said mast during angle drilling.

11. The back brace as recited in claim 5 in which said lower brace member includes an inner and an outer section which are telescopically connected to one another to provide a means of adjusting the length of said lower brace member. 7

Claims

1. In a drill having a mast which is connected to a frame for pivotal motion between an upright drilling position and a transport position, a back brace comprising: a strut having one end connected to the mast, having its other end connected to the frame, and having a knee intermediate its ends which provides a joint at which the strut folds when the mast is lowered from its upright drilling position; a knee brace having one end pivotally connected to a point adjacent the foot of the mast and having a free end which is slidably retained to the strut intermediate its ends; and a locking mechanism associated with said strut and said knee brace, said locking mechanism being operable when said mast is raised to its upright drilling position to fasten said knee brace to said strut and to thereby lock said strut in an unfolded position.

5. In a drill having a mast which is connected to a frame for pivotal motion between an upright drilling position and a transport position, a back brace for supporting the mast during drilling which includes two sections each comprising: an upper brace member having one end connected to said mast at a point intermediate the ends of the mast; a lower brace member having one end pivotally connected to the other end of said upper brace member to form a knee and having its other end connected to the drill frame at a point which is substantially spaced from the foot of the mast; a knee brace having one end pivotally connected to the frame at a point adjacent the foot of the mast and having its other end slidably retained to said knee; and a locking mechanism associated with said knee brace and operable to fasten said knee brace to said knee when the mast is in its upright drilling position.

9. The back brace as recited in claim 8 in which each locking mechanism includes power actuated means for unlocking its hook shaped plate and associated support shaft.

11. The back brace as recited in claim 5 in which said lower brace member includes an inner and an outer section which are telescopically connected to one another to provide a means of adjusting the length of said lower brace member.