US2584330A

US2584330A - Percussion rock drill

Info

Publication number: US2584330A
Application number: US165635A
Authority: US
Inventors: Craig Ernest
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-06-02
Filing date: 1950-06-02
Publication date: 1952-02-05
Anticipated expiration: 1969-02-05

Description

Feb. 5, 1952 E. CRAIG PERCUSSION ROCK DRILL 2 SHEETSSHEET 1 Filed June 2, 1950 Feb. 5, 1952 7 E. CRAIG 2,584,330

PERCUSSION ROCK DRILL Filed June 2, 1950 I 2 SHEETS-SHEET 2 [n n enzor' 'Ernesf Craig Patented Feb. 5, 1952 PERCUSSION ROCK DRILL Ernest Craig Lakefie'ld, Ontario, Canada Application June 2, 1 Seri l N 1:65.63

. 5' Claims.

This invention relates to improvements in percussion rock drills of the type in. which a rapidly rotating hammer is, utilized to. strike the drill shank or a tappet interposed between, the drill shank and hammer to thereby effect. rapid 'vibratory reciprocation of the drill shank in the direction of its length.

In the past such rotary percussion drills normally have the hammer mounted on a rotor, which is rotated about its axis which is fixed in relation to. the drill and the. hammer is movable relative the rotor to strike the t'appet or steel and then recoil. 'In' some cases. the hammers are pivoted to the rotor and in some cases run on trackways, as for example in my United- States Patent No. 2,392,233, issued January 1, 1946..

Such drills are subject to several disadvantages. one particular disadvantage is that the. blow delivered by the hammer is not by any means entirely in the direction of the length of the drill shank or steel but has a relatively large. component of movement in a transverse direction due to the rotative motion of the rotorarid there is considerable slippage or dragging of the hammer over the steel in following the movement of the rotor, resulting in loss of efficiency and wearing.

Further, there is considerable recoil back to the rotor or trackway where employed, due to bouncing of the hammers, resultin rapid wearing of the drill parts, discomfort to the operator and short life operation for the drill.

The principal object of the present invention. is therefore to provide animproved hammer action in which the rotary motion of the drill rotor will be converted into hammer motion to now directed longitudinally of the steel while causing the hammer to subsequently lift. without dragging over the steel.

In a particular form of the, invention one or more cages are mounted on a driven rotor for rotation about an axis offset from the axis of the rotor. A hammer element, is mounted in each cage to swing about. a pivot offset from the axis of the cage, the cage being driven upon rotation 1 he rotor throu h an ep cl i l gear fat the tappet. or steel sh nk roi ite i to h path of the hammer with the hammermovin at impact with the tappet under centrifugal force resulting from the com osite motion of orbital translation and rotation of the cage essentially .in a direction aligned with the tappet.

Another feature of the invention resides in the provision for accurately timing the cage movee ment to deliver the correct hammer stroke.

deliver a positive accurately placed percussion f blow through to the steel in the direction of its length, and to subsequently lift the hammer in the direction from which the hammer blow was Y delivered to thereby eliminate slippage or drag-p j 'ging of the hammer over the steel to provide a more eflicient drill in which wear will be reduced to a minimum for long life operation.

Another important object is to relieve shock to the hammer supporting rotorjand'rotor' driva A further object is to provide adrlll having a balanced operation.

Still another object is to provide a percussion drill of efficient and economical construction.

The principal feature of the invention resides in constructing a percussionw drillemploying an epicycloidal wheel arrangement iorconvertih rotative motion into substantianypu're linear. reciprocating motion. to give. an efieptive' hammer Still another feature resides in th rovision of a hammer constructed for optimum efiiciency in transferring its kinetic energy to the tappet or steel on impact.

Referring to the accompanying drawings, Figure 1 is a vertical sectional view on the line l-el of Figure 2 through a percussion'drill constructed in accordance with this invention. I

Figure 2 is a vertical sectional view taken through the drill at right angles to Figure 1 on the linev 2 2 of Figure 1.

Figure 3 is a perspective view of the inner wheel or timing gear oi the drill cage. t

Figure 4 is a perspective view of one form of hammer which may b3 employed.

Figure 5 is a perspective view of the cage for a hammer of th t pe of Figu e 4- Figure 6 is aperspe'ctive view of an alternative form of cage of a preferred form.

Figure 7 is a perspective view of the hammer to be used with the cage of Figure 6.

Figure 8 is a perspective view of the cage gear for the c ge of- Fisu e igure Bis a vertical sectional view t ou h the case-of Figure 6 wi h the ham r in la a d showing th relation f the as and hammer as the hamm r is d li e in its mpact blow to the ta pet.

With refer nce to the drawi gs the drill casing l is shown as a c rcular casting formed h nal flanges}. and an axial y fiset ext 3 having a centra bore 01' pa sage 4 in whi h is slidably received a tappet or steel shank to project within the casing.

Secured to the casing I are the closing face plates 5 and held outwardlyfrom the flanges 2 by their circular flanges 8 under the clamping action of the bolts 9.

Each of the face plates 6 is formed with a central journal boss II! in which is mounted a journal I I held in position by a plate I2.

Rotatably supported in each of the journals I I is a rotor member I3 in the form of a flanged collar mounted on a hub I4 having a shaft extension I6 entered in the journal I I. These rotor members I3 are formed to receive journals I8 held in position by plates 20.

The journals I8 of the opposing rotor members I3 are axially aligned and journalled therebetween are ca es 22 formed with axially aligned stud shafts 23 received within the journals.

Mounted within the flange 8 of one of the face plates 6 is an internally toothed ring gear 24, and mounted on bosses 25 formed on one face of the cages 22 concentric with its stud shaft 23 aregears or toothed wheels 25' of annular form arranged to mesh with the ring gear 24.

The ring gear 24 is fixed and the gears 25' of the cages have a diameter substantially one half that of the ring gear and are arranged on the rotor members 53 to revolve about the centre of the internal gear while meshing therewith to form an epicycloidal wheel arrangement wherein motion of points offset from the axes of the stud shafts 23 of the cages towards the circumference of the gears 25' have a linear motion.

Each of the cages 22 is provided with a recess 26 opening inwardly from the periphery thereof, and inserted in each of these recesses is a hammer 21 which, in the form shown in Figure 4, has a shank portion 28, head 29, formed with a striking face 30.

The hammer 2! is pivoted on pin 3I to swing about an axis parallel to the axis of the cage 22 in which it is mounted but offset towards the periphery of the cage. The hammer 2! is permitted limited movement within the recess 26, and to accommodate this movement it is formed with the guide grooves 32 into which project the stop ribs 33 formed on the inner faces of the cage recess 28 and of substantially lesser width than the grooves 32. I

As shown in Figure 1, the timing of the epicycloidal wheel as formed by internal gear 24 and cage gear 25' is such as to bring the hammer striking face 30 of each cage into position to strike the tappet or steel 5 while moving essentially in the direction of the length of the tappet.

Operation In Figure 1 the direction of the rotor members I3 as driven through the shaft 2I is anti-clockwise. The rotors carry the cages 22 bodily so that they are being bodily revolved about the axis of the rotors and ring gear in an anticlockwise direction. The cages in turn are meshing with the ring gear 24 and being rotated thereby in opposite direction to their bodily revolution. The direction of the rotation of cages about their own axes is therefore clockwise and at twice the speed of the rotor due to the relationship of the cage and its gear 25' being onehalf the diameter of the ring gear as explained, and this relationship converts the rotary motion of the cage and rotor into essentially a reciprocal hammer blow directed longitudinally of 4 the tappet as hereinafter more particularly described.

The hammers 21 carried by the cage are urged outwardly of the centre of the rotor under centrifugal force. The hammer pivots move sub stantially on a diameter of the rotor or ring gear 24 and the timing of the gears 24 and 25' are such that the hammers are positioned as they reach the steel 5 as shown in Figure 1 to be moving clockwise about their pivots at a speed in excess of the cages under centrifugal force with the motion component of the hammer heads at impact being substantially aligned with the axis of the tappet 5 to deliver the desired percussion blow.

After the impact the cages continue to rotate clockwise about their own axes while being revolved bodily anti-clockwise to effect a lifting of the hammer from the steel in a direction from which the hammer blow was delivered to prevent the hammer from being dragged past the steel as in previous constructions. That is, at the instant of impact the hammer pin 3|, due to the clockwise motion of the cage, is moving from a position in retard of the tappet in relation to the direction of rotor movement inwardly of the rotor axis with the above noted result.

The hammer is designed to have sufficient weight to carry through to some extent after the blow although the hammer must also be permitted to lift after the blow so that the drill will not vibrate excessively. and also the hammer must be balanced so that the impact is a balanced blow on the steel.

It will be seen in Figure 1 that the hammer at impact is displaced to leave an air pocket 34 at its rear in relation to its direction of impact delivery and this air pocket may be utilized to cushion any lift of the hammer.

Figures 6 to 9 shown an alternative form of cage and hammer arrangement. The cage 35 of Figure 6 is formed with the shaft extensions 36, permitting it to be journalled between the rotor members I3 in aligned journals I8. One face of the cage is formed with a concentric hub 31 corresponding to the hub 25 on the cage 22 to receive the annular gear 38 corresponding to the gear 25'.

The cage 35 is formed with a recess 39 diverging at 40 to form a wide mouth extending for a considerable sector of the cage, with the cage at one side of the mouth being slotted to form the jaws 4|.

The hammer 42 is formed with a shank 43 and an enlarged head 44, fitting within the recess 39 and diverging mouth 40 respectively of the cage. The enlarged head 44 is formed with a striking base 45 of convex form which extends between the jaws M. The hammer is pivoted in position by the pin 46 extending through the cage and into the groove 4'! formed in the inner perimeter of the annular gear 38.

Figure 9 shows the position of the hammer and cage of Figures 6 to 8 at the instant of impact, with the cage being rotated clockwise in the direction of the arrow. It will be seen that the hammer is moving at impact relative the cage to its position outwardly of the centre of the cage w as limited by the stop surface 48, and the blow will be under the epicycloidal arrangement in the direction of the tappet.

The lifting of the hammer after follow through under, the motion of the cage will eliminate any detrimental rebound action, and the hammer will deliver a balanced effective percussion blow.

It will be understood that the rotor of the machine is heavy enough to carry the cages through impact, therefore relieving shocks to the timing gears. Also the cages are of sufficient weight so that the hammer force on the steel at impact is allowed to deliver its blow without lifting the cages or carrying the shock from the hammer through the cages to the body of the machine.

While the actual timing of the cages is determined by the ring gear 24 and meshing cage gears, it is desirable that provision be made to adjust this timing through the range of one tooth of the ring gear to deliver the percussion blow in precisely the desired direction. To this end the internal gear 24 is secured to the flanges 2 of the circular casing by means of the bolts 49 selectively engageable in the threaded orifices 50.

It will be appreciated that a machine of the type described will aiford an extremely efiicient percussion drill in which the rotary drive motion is transferred into the desired straight line percussion blow; that such a machine will be compact and rugged and will operate with the minimum of wear on the moving parts for long life operation. I

While the above description discloses a specific embodiment of my invention it will be appreciated that variations and modifications may be made within the scope of the appended claims. It will be noted that hereunder the term tappet is to include a separate tappet element on the drill steel in the event such tappet element is not employed.

What I claim as my invention is:

1. In a percussion drill, a casing, an internally toothed gear ring mounted within said casing,

a cage revolvable about the centre of said gear and having a gear substantially one-half the diameter of said ring gear meshing with said ring gear, means for revolving said cage about the centre of said ring gear, a tappet reciprocally arranged to project within said casing, and a hammer carried by and movable relative to said cage, the timing of said gears being arranged'to bring said hammer against said tappet member while moving with substantially linear motion in a direction aligned with said tappet.

2. In a percussion drill, an outer internally I toothed ring gear and an inner gear substantially one-half the diameter of said ring gear mounted for revolution around the axis of said ring gear and meshing therewith to form an epicycloidal wheel, means for revolving the inner gear around the axis of said ring gear, a tappet member reciprocally arranged to project within said casing, and a hammer carried by said inner gear to strike said tappet.

3. In a percussion drill, a casing, an internally toothed ring gear mounted within said casing. a

rotor mounted to rotate on the axis of said ring gear, a cage of substantially one-half the diameter of said ring gear eccentrically and rotatably mounted on said rotor and provided with a gear of a diameter equal to cage diameter meshing with said ring gear, means for revolving said rotor to drive said cage through said ring gear at twice rotor speed, a hammer carried by'said cage and having a striking face moving in a substantially linear path under rotor and cage rotation, and a tappet reciprocally arranged to project within said casing, the timing of said ring and cage gears being arranged to bring said hammer face against said tappet while moving with substantially linear motion in the direction of said tappet, said hammer being'mounted for movement relative said cage upon striking said tappet.

4. In a percussion drill, a casing, an internally toothed ring gear mounted within said casing, a rotor mounted to rotate on the axis of said ring gear, at least one cage of substantially onehalf the diameter of said ring gear eccentrically and rotatably mounted on said rotor and provided with a gear of a diameter equal to cage diameter meshing with said ring gear, means for revolving said rotor to drive said cage through said ring gear at twice rotor speed, said cage having a slot therein opening to the periphery thereof, a hammer mounted in said slot for limited movement relative said cage, and a tappet reciprocally arranged to project within said casing, the timing of said ring and cage gears being arranged to bring said hammer against said tappet while moving in a direction substantially aligned with the longitudinal direption of said tappet.

5. A device as claimed in claim 4 in which said internally toothed ring gear is mounted for rotary adjustment relative said casing to control the timing of said hammer, and means are provided to fix said ring gear in adjusted timing position.

ERNEST CRAIG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS