US1923796A - Rock drill - Google Patents

Description

J. E. @ENFER mg@ w33? ROCK DRILL Filed May 22, 1930 2 Sheets-Sheet 2 INVENTOR WM a M Patented ug. 22, 1933 UNITED STATES PATENT OFFICE Cleveland Rock Drill Company,

Cleveland,

Ohio, a Corporation of Ohio Application May Z2, 1

6 Claims.

This invention relates to fluid actuated machines of the rock drill type, and specically to an improved valve mechanism for distributing motive fluid to such machines. Y

One object of this invention is to effect the distribution of motive fluid to the opposite ends of a cylinder of a fluid actuated machine with a minimum pressure drop between the fluid supply line and the working chambers to thereby increase the eiciency of the machine.

Another object is to supply motive luid to the opposed working chambers with an appreciable lag therebetween, to insure the delivery of the full force of the piston hammer to the drill steel or tool.

Other objects are to provide an improved simplied valve construction; to arrange the elements of the valve to obtain rapid opening and closing of the iluid ports; to provide a novel lubricating means for a fluid actuated machine; and to arrange the parts of the machine in such a manner as to facilitate and simplify the assembly thereof.

Other objects relating to details of construc- D tion and economies of manufacture will appear hereinafter.

In the accompanying drawings, which illustrate a preferred embodiment of the invention:

Fig. 1 is a vertical medial section through a rock drill constructed in accordance with this invention and showing the relation assumed by the parts near one extreme oi the piston travel.

Fig. 2 is a similar View showing the relation assumed by the parts near the opposite extreme of the piston travel.

Referring to the drawings, the improved machine is housed within a cylinder 5, a front head 6, and a back head 7 secured together in the usual manner by side rods (not shown). A piston hammer 8 is slidably mounted within the cylin er and has a riiled axial opening slidably receiving a riiied bar 9 which cooperates in the usual manner with a rotation mechanism 10. The latter is supported between the cylinder 5 and back head 7 in a sealing chamber which consists of a plate 11 seated on an annular shoulder 12 near the end of the cylinder, a ring 13 seated on the plate 12, and a plate 14 seated on an internal shoulder in the ring 13. The riled bar 9 passes through a central aperture in the plate 11 into the cylinder 5. The piston 8 is provided f with a splined stem 15 which cooperates in the usual manner with a chuck 16 to rotate the tool or drill steel 17.

The wall of the cylinder 5 is formed with a 930. Serial No. 454,549

hollow cylindrical enlargement 18 which houses the valve mechanism. A sleeve 19 forming one element of the valve is slidably mounted in the central portion of the enlargement 18 and has its opposite ends bearing in the bores 20 and 21 60 oi the enlargement. intermediate the bores 20 and 21 is an expanded opening 22 spaced from the sleeve 19 to provide a lubricant reservoir 23.

The bore 2O terminates in an annular recess 24 the entire inner side of which opens into an annular recess 25 in the cylinder 5. Beyond the recess 24 the enlargement 18 is formed with a bore 26 slightly larger in diameter than the bore 20 and receiving a bushing 27 having a 'flange 28 seated upon the end of the enlargement 18. A sleeve 29 is slidably mounted within the bush ing 27 and is provided with a flange 30 bearing in the bore 26.

At thn opposite end of the enlargement 18 the bore 21 terminates in an annular recess 31 opening into a recess 32 in the cylinder 5. A bore 33 beyond the recess 31 receives a plug 34, and a sleeve 85 having a flange 36 isV slidable inthe plug 34 and the bore 33.

The sleeves 19, 29, and 35 are axially aligned and constitute the distributing valve for controlling the flow of motive iluid to the opposite ends of the cylinder. The ends of the sleeve 19 are arranged to abut the adjacent ends of the sleeves 29 and 35 to interrupt communication between the interior of the sleeves and the respective recesses 24 and 31, and are accordingly provided, in the preferred embodiment of the invention, with packing 52 made of rubber or l other suitable material. The packing 52, which is retained in recesses in the ends of the sleeve 19, seats against the sleeves 29 and 35 to provide an efficient seal and also cushions the movement of the sleeve. If desired, the packing can be omitted in which case the ends of the sleeves must be machined with extreme accuracy in order to prevent leakage of the motive iluid.

Packing 37 of any suitable type is disposed between the ange 28 of the bushing 27 and the back head 7. When the drill is assembled the head 7 first engages the packing 37 and compresses the same. The ring 13 is made of sufcient height to engage the head 7 and prevent contact thereof with the cylinder 5. TheV side rods or other securing means are Vthen drawn down tightly to form a fluid tight seal between the head 7 and the packing 37 and between the head and the ring 13, leaving a space 38 between thev head and the cylinder 5. The working chambers of the machine are thereby completely sealed and the va ious parts are rigidly maintained in position.

A source of motive fluid is connected with the supply duct 39 in the usual manner and is controlled by the throttle valve of any suitable type. A port 4G leads from the duct 39 through the packing 37 tothe interior of the bushing 27. An exhaust port 41 is formed in the wall of the cylinder 5 and is arranged substantially closer to the r s 32 than to the recess 25. A pair of cro d conduits 42 and 43 open through the wall ci the cylinder at spaced points on opposite sides ot the exhaust port 41. The conduit 42 opens into an annular space 44 between the flange 36 and the plug 34, and the conduit 43 opens into a similar annular space 45 between the flange 30 and the bushing 27.

The adjacent end faces of the sleeves 19 and 29 are ester ally grooved tc :form pressure areas 46 and 47, respectively. Similar pressure areas 43 and 49 are formed on the adjacent end faces of the sleeves 19 and 35. The sleeves 29 and 35 are consti-ucter with internal diameters smaller than the internal diameter or the sleeve 19 to form interior pressure areas 59 and 5l on the sleeves 29 and 35, respectively. These pressure areas 59 5l are suiliciently larger than the areas of the ends oi the sleeves 29 and 35 remote from the shove 19 to provide constant pressures tending to hold the sleeves 2S and 35 away in the sleeve 19 when the pressures in the annular spaces 44 and 45 are less than the sure within the sleeves.

The lubricant reserv ir 23 is provided with filling opening at any convenient point in the wall of the enlargement 18, and is arranged to supply lubricant to the valve and piston. The lubricant passes between the sleeve 19 and the bores 29 and 21 capillary action, and is entrained in the motive fluid through a small port 46 formed in the sleeve 19. The pulsations in the motive iluid created by operation of the machine force lulrcant through the port 45', the reservoir 23 be g full of lubricant, the lubricant exudes through the passage 46 onto the inner walls oi the sleeve 19 the compressed air, passing through the sleeve 19, carries lubricant into the cylinder the usual manner.

In operation, assumeVV the parts are in the position shown in l. When the throttle valve is opened, air flows through the duct 39 and the passage 4 between the ends of the sleeves 19 and 29, and through the annular recess 24 into the upper end of the cylinder 5. The valve elements are held in position by the pressure of the incoming air acting against the lower end of the sleeve 29 and flange 30 and the upper end of the sleeve' 19 and against the pressure area 5l, the upper side or the flange 30 being open to atmosphere through the conduit 43 and port 41 and the pressure areas 48 and 49 being open to atmosphere through the recess 31 and port 41. The pressure of the air acting against the upper side of the piston 8 forces the same downwardly to deliver a blow to the drill steel 17. The piston is shown in Fig. 1 just after the beginning of this downward stroke.

As the piston moves downwardly the upper edge thereof uncovers the conduit 42, admitting air to the space 44 to act against the under side of the flange 33. This flange is of such area that the pressure thereagainst overcomes ecess the pressure acting against the upper end of the sleeve 19 and the area 51, and the sleeves 19 and 35 are therefore moved upwardly until the upper end of the sleeve 19 seats against the lower end of the sleeve 29, thereby cutting oi all flow ci air to the cylinder.

The piston continues its downward movement under inertia and the expansion of the air in the upper end of the cylinder and the exhaust port 41 1's then uncovered. At this time air is being compressed slightly in the lower end of the cylinder, this compression having begun vhen the lower end of the piston passed the exhaust port 41. This slightly compressed air acts against the pressure areas 48 and 49, but with insufficient force to change the relation oi the valve elements. As the air exhausts from the upper end oi the cylinder, the pressure in the space 44 is relieved through conduit 42 and exhaust port 41. The air which has been compressed in the lower end oi the cylinder acts against the pressure area 49, and together with the constant pressure acting on the pressure area 51, nieves the sleeve 35 downwardly. At the same time the compression in the lower end oi the cylinder acts on the pressure area 48 to hold the sleeve 19 in its raised position. Live air from the supply line thereupon ilows between the ends of the sleeves 19 and 35 to the lower end of 'he cylinder 5 just as the pisto delivers its blow to the drill steel 17. i

At this time the parts are in the position illustrated in Fig. 2. The sleeve 29 is held in its raised position by the live air acting against the pressure area 59, and the sleeve 19 is held in raised position by the pressure against the lower end thereof. As the piston moves upwardly under the influence of 'the live air adinitted te the lower end or^ the cylinder, the conduit 43 is uncovered and air hows therethrough toy the chamber 45 to act upon the upper side ci the flange 39 and force the two sleeves 19 and 29 downwardly, cutting off all flow oi air to the cylinder. When the lower edge of the piston uncovers the exhaust port 41 the pressure in the space 45 is relieved through conduits 43 and exhaust port 41, allowing the sleeve 29 to move upwardly under the iniluence of the constant pressure acting on thepressure area 59 together with the come pression in the upper end of the cylinder acting against the pressure area 47. The force against the pressure area 46 holds the sleeves 19 and 35 in their lowermost positions and as a consequence air is again admitted to the upper end of the cylinder between the ends of the sleeves 19 and 29.

j The exhaust port 41 is located substantially closer to the lower end of the piston stroke than to the upper in order that live air will be ad- .mitted to the lower end of the cylinder after the piston has delivered its blow to the drill steel, and will be admitted to the upper end in ample time to check the upward movement of the piston and prevent the same from striking plate 11.

It will be evident that the air passages to both ends of the cylinder are relatively large and unobstructed and that as a consequence the pressure drop through the valve is relatively small. This permits efcient operation of the drill on low air pressures and also makes possible a more rapid action and the delivery of a more powerful blow to the drill steel. Since the downward stroke oi the pistonV is not cushioned by the incoming air the full force of the momentum acquired by the piston is delivered to the drill.

It will also be evident that a relatively small movement of the valve members produces a relatively large opening. The pacliings 37 and 52, in addition to sealing the air passages, serve as cushions for the valve members during their movement and decrease the Wear on the parts. If desired, a packing similar to the packing 37 may be employed beneath the plug 34. The lubricant reservoir 23 insures free action or" the valve and in addition provides a convenient means for lubricating the entire machine.

While the foregoing description is necessarily of a detailed character it is to be understood that the specific terminology employed is not to be construed as restrictive or limiting, and it is to be further understood that various rearrangements of parts and modiiications may be resorted to without departing from the scope or spirit of the invention as claimed herein.

I claim:

l. In a rock drill having a cylinder and a piston reciprocable therein, a distributing valve including a sleeve, means for admitting motive fluid into said sleeve, conduits communicating with the opposite ends of said sleeve and the opposite ends of said cylinder, means for interrupting communication between said sleeve and said conduits, and means responsive to pressure within the cylinder developed by movement of the piston within the same for maintaining said sleeve out of communication with one of said conduits while establishing communication of said sleeve with the other conduit.

2. In a iluid actuated machine having a cylinder and a piston reciprocable therein, a valve for controlling the flow of fluid to the opposite ends or" said cylinder, said valve including a pair of sleeves disposed in abutting relation, means for admitting' motive iiuid into said sleeves, and means responsive to pressures developed in said cylinder by said piston moving within said cylinder adapted to separate said sleeves to admit motive uid to one end of said cylinder.

3. In a uid actuated machine having a cylinder and a piston reciprccable therein, a valve for controlling the flow of iiuid to the opposite ends of said cylinder said valve including a pair of movably mounted abutting sleeves, means for admitting motive iiuid into said sleeves, means actuated by pressure iluid for moving both said sleeves to interrupt the iiow of fluid to one end of said cylinder, and means actuated by pressure developed in said cylinder by the movement of the pistontherein for separating said sleeves to admit motive fluid to the other end of the cylinder.

4. In a iiuid actuated machine, a hollow valve casing, and valve means including a sleeve slidable in said casing, said casing being enlarged intermediate the ends of said sleeve to form therewith a lubricant reservoir, and to lubricate said slidable sleeve, said sleeve having an opening therethrough for the passage of lubricant into the interior or said valve means.

5. In a iluid actuated machine having a cylinder and a piston reciprocable therein, a fluid passage communicating with both ends of the cylinder, valve means formed of three elements slidably disposed in said passage, means actuated by motive fluid for moving said elements to interrupt the ow of motive fluid alternately to the opposite ends of the cylinder, means responsive to drop of pressure within said cylinder to move two of said elements apart and means responsive to compression within said cylinder to maintain said last mentioned elements in their oppositely moved position.

6. In a fluid actuated machine having a cylinder and a piston reciprocable therein, a fluid passage communicating with both ends of the cylinder, a sleeve slidably disposed in said passage and a sleeve slidably disposed in said pasi sage on each side of said first named sleeve providing three sleeves in all, pressure surfaces on opposite sides of each of said sleeves, there being a conduit communicating centrally with the cylinder and with the pressure surface on one of said end sleeves, there being a second conduit communicating centrally with said cylinder and with the pressure surface on one side of the other end sleeve, the iluid passage communicating with the ends of the cylinder also serving to communicate with the pressure sur` face on the opposite sides of said end sleeves and with the pressure surface on said irst mentioned sleeve and means for admitting motive fluid to the interior of said sleeves.

JOHN E. RENFER.

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