Rock drill

Oct. 13, 1942.

J. R. HICKS

ROCK DRILL

2,298,792

Filed June 27, 1941

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Patented Oct. 13, 1942

2,298,792

UNITED STATES PATENT OFFICE

2,298,792

ROCK DRILL

John Royal Hicks, Sargents, Colo.

Application June 27, 1941, Serial No. 399,977

Claims. (Cl. 255—43)

This invention relates to an electric rock drill and has for its principal object the provision of a simple and highly efficient mechanism for driving rock drills which can be operated directly from a standard electric motor mounted directly 5 upon the drill, thus, eliminating all air hoses, compressors, piping, etc.

Other objects of the invention are to provide a construction in which the blow delivered to the drill will be entirely independent of the 10 speed or power of the motor; in which means will be provided for assisting the motor in returning the hammer after the blow has been struck; to provide an efficient construction by means of which the hammer portion of the drill 15 can be quickly and easily removed and replaced when necessary.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efficiency. 20 These will become more apparent from the following description.

In the following detailed description of the invention reference is had to the accompanying drawing which forms a part hereof. Like nu- 25 merals refer to like parts in all views of the drawing and throughout the description.

In the drawing:

Fig. 1 is a plan view of one form of the improved rock drill;so

Fig. 2 is a side view thereof;

Fig. 3 is an enlarged longitudinal section through the drill, taken on the line 3—3, Fig. 1;

Fig. 4 is a cross section, taken on the line 4—4, Fig. 3;35

Fig. 5 is a similar cross section, taken on the line 5—5, Fig. 3; and

Fig. 6 is a fragmentary side view of the barrel of the drill illustrating the elongated slots formed therein.40

The improved drill may be supported on any kind of bed or bracket suitable for the particular job upon which it is to be used. It is provided with a dove-tailed base portion 10 by means of which it may be securely clamped to ⁴⁵its support. The dove-tailed base is formed on a gear box 11 which is closed by means of a suitable cover plate 12. A tubular barrel 15 is formed on and projects forwardly from the gear box II. The forward extremity of the bar- 50 rel 15 is internally threaded to receive a chuck sleeve 17 in which a drill chuck member 18 is slidably mounted to receive the head of a drill steel 19.

A cylindrical piston 20 is slidably mounted 55 within the barrel 15. The piston is formed at its rear extremity with a recess 21 for receiving the head of a connecting rod 22. The connecting rod is mounted on a wrist pin 23 which extends entirely through the piston 20 and through the opposite sides of the barrel 15, through elongated slots 13 therein.

The extremities of the wrist pin 23 project oppositely outward from the barrel 15 through a sliding sleeve 25 on the exterior of the barrel

15. The other extremity of the connecting rod 22 terminates in a crank pin 26 which rides in an elongated circumferential slot 27 formed in a crank disc 28.

The crank disc is fixedly mounted on a crank shaft 29 extending outwardly through a bearing sleeve 30 in one side of the gear box II. The sleeve 30 extends inwardly to the crank disc 28 to prevent outward movement of the shaft.

Worm gear teeth 14 are formed in the periphery of the crank disc 28. These teeth are in mesh with a toothed worm 16 secured on a worm shaft 24. The worm shaft is carried in pedestal bearings 31 extending from the cover plate 12 so that the worm shaft may be removed by removal of the cover plate. The worm shaft carries a driven gear 32 which meshes with a drive gear 33 of an electric motor 34. The motor is provided with a mounting flange 35 which is secured to the rear wall of the gear box by means of suitable attachment screws 36.

A chuck collar 37 is secured on the forward extremity of the chuck sleeve 17 by means of a set screw 38. Hinge pins 39 project oppositely outward from the chuck collar to support a typical drill retaining yoke 40. A pair of hammer springs 41 extend between the extremities of the hinge pins 39 and the extremities of the wrist pin 23 at each side of the barrel 15.

It can be readily seen that as the motor operates, it will rotate the crank disc 28 in a counterclockwise direction, in Fig. 3. This causes the trailing extremity of the arcuate slot 27 to engage the crank pin 26, as shown in Fig. 3, so as to draw the piston 20 rearwardly. When the crank pin 26 passes the axial or dead center position of the disc 28, the springs 41 will operate to snap the piston forwardly, the crank pin traveling forwardly in the arcuate slot 27 without effecting the rotation to the crank disc 28.

It will be noted that the power of the motor is oiily utilized in stretching the springs 41 and that ordinarily during the remainder of the rotation of the crank shaft no power would be required. The irregular absorption of power is

2,298,792 counter-balanced by means of a counter-balance spring 42 which extends between a fixed spring pin 43 on the base 10 and a rotating spring pin 44 which is eccentrically carried on a spring disc 45 secured on the outer extremity of the crank shaft 29. Thus, while the motor is withdrawing the piston against the action of the springs 41, the counter-balance spring is assisting the rotation of the crank shaft 29, as shown in Fig. 3. As soon as the motor is released from the reaction of the springs 41 the spring pin 44 will have reached a position where it will begin to stretch the counter-balance spring 42 during the idle cycle of operation. Thus, when not operating the piston 20, the motor is storing energy by stretching the spring 42.

A hammer 46 is rotatably secured on the head of the piston 20 by means of an axially positioned attachment screw 47. The screw 47 is locked in place by means of a suitable cotter key

49. This hammer has a fluted head 48 extending into the drill chuck member 18 to a point where it may strike the head of the drill steel 19 therein at each forward stroke of the piston 20.

The yoke 40 prevents the drill from falling from the chuck member. The drill is rotated while drilling by means of a handle 50 projecting outwardly from a handle ring 51 which is rotatably held on the chuck member 18 by means of a retaining collar 52 which is secured on the forward extremity of the chuck member by means of suitable set screws 53. The handle ring 51 rotates alongside a ratchet gear 54 which is secured on the chuck member 18 so as to rotate therewith. A ratchet pawl 55, mounted on a pawl pin 56 in the handle 50, engages the teeth of the ratchet gear at each reciprocation of the handle 50 to partially rotate the chuck member 18 and through it the drill steel 19.

While a specific form of the improvement has been described and illustrated herein, it is desired to be understood that the same may be varied, within the scope of the appended claims, without departing from the spirit of the invention.