US2559478A

US2559478A - Hydraulic impact tool

Info

Publication number: US2559478A
Application number: US61341A
Authority: US
Inventors: Albert L Stone
Original assignee: STONEFIELD Inc
Current assignee: STONEFIELD Inc
Priority date: 1948-11-22
Filing date: 1948-11-22
Publication date: 1951-07-03
Anticipated expiration: 1968-07-03

Description

2 Sheets-Sheet 1 A. L. STONE HYDRAULIC IMPACT TOOL July 3, 1951 Filed Nov. 22, 1948 I INVENToR. LBEQT L. STO/v5,

TTQQNEY.

July 3, 1951 A. L. STONE HYDRAULIC IMPACT TOOL 2 Sheets-Sheet 2 Filed NOV. 22, 1948 INVENTOR. ALBERT .STO/v5,

HrvoQ/vex Patented July 3, 1951 HYDRAULC IMPACT TGL Albert li. Stone, Palos Verdes Estates, Calif., as-

signor to Stonelield, Incorporated, Redondo Beach, Calif., a corporation of California Application November 22, 1948, Serial No. 61,341

9 Claims. 1

This invention relates generally to improved powered impact tools, such as chipping hammers and the like, and concerns more particularly such tools especially adapted for hydraulic actuation.

The invention is directed generally toward the development of an impact tool operable to intermittently store hydraulic energy within a resiliently compressible medium, such as a spring, and to then suddenly release that energy to impart a powered blow. It is a maior object of the invention to provide such a tool operable by relatively low fluid pressure to impart intermittent blows with a force not attainable by direct application of the fluid pressure to the striking element. To achieve this result, I employ yielding means, such as a spring, operable when compressed to urge a hammer or other reciprocable element rapidly in an advancing direction, together with hydraulic means for retracting the element to a predetermined position against the tendency of the spring. In accordance with the invention, such retraction is effected by use oi a hydraulically retractable actuating element in combination with means for interconnecting it and the hammer element during powered retraction, The interconnecting means may comprise mechanism carried by the piston automatically operable upon movement of the piston to advanced position to grasp the hammer, and automatically releasable as the piston nears retracted position to permit advancing movement of the hammer.

As an actuatingT element, I preferably employ a piston hydraulically movable in retracting direction and having a piston rod associated with the above mentioned interconnecting means whereby the hammer is connected to the rod during retraction and automatically released from retracted position. The piston may be urged in advancing direction 'after release of the hammer by suitable yielding means, as by a spring operating against the hydraulic retracting action.

1t is a further object oi the invention to provide a fluid pressure actuated impact tool including novel valve means adapted to control pressure fluid intake and discharge within the power cylinder. For this purpose, I disclose a valve. element automatically shiitable between intake and discharge positions as a reciprocally moving piston reaches the limits of its travel. Preferably, the valve comprises a tubullar member longitudinally movable within the tool body and operable to alternately uncover separate inlet and discharge openings. To shift the valve member in one direction between its two positions, I desirably employ yielding means such as a coil spring, `adapted to be compressed as the piston.

gli.

ypressed to a predetermined extent.

nears the limit position and operable to rapidlly move the valve against the influence of releasable detent means after the spring has been comsupple' mental-y non-yielding means may be provided in connection with the spring to `positively initiate shifting of the valve, the shifting then being completed by the spring compression.

Another object is to provide an impact tool design in which the work engaging element is operable as long as the weight of the tool rests upon it, but ceases to be driven when the tool is raised.

The above and further features and objects of the present invention will be better understoodk from the following detailed description of the typical embodiment illustrated in the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional View of the tool showing the piston and associated parts in retracted position and the hammer commencing its advancing movement;

Fig. 2 is a sectional view showing the tool of Fig. 1 after the hammer and piston have both reached advanced position;

Fig. 3 is an enlarged fragmentary sectional View showing the apparatus during retraction;

Fig. 4 is a transverse section taken on line 4-4 of Fig. 3; and

Fig. 5 is a transverse section taken on line 5 5 of Fig. 3.

The hydraulic impact tool shown in the drawings comprises essentially a tubular tool body including four cylindrical sections I0, Il, I2 and I3, hammer element I4 yieldingly urged downwardly into striking engagement with tool element I5, power piston I6. hydraulically movable in an upward retracting direction, piston rod I1 carried by the piston, valve means I8 for controlling the admission and ldischarge of pressure iiuid into body sections I0 and Il beneath the piston, and interconnecting means IB for intery locking the piston rod and hammer during re-v 3 in position by face plate 21, and as secured to piston rod I1 by nut 28.

Body section II, threadedly carried about section I8 at 81, may be provided with thicker side walls than section i to permit attachment of Inlet line 29 and discharge line 3o by threaded reception in the enlarged outer portions of inlet SI and outlet 32. .Near its lower end, section II includes a transverse partition 39 which acts as the bottom closure for the hydraulic cylinder. The partition has a central opening 89 through which the piston rod extends. Interiorly, body section II presents a cylindrical bore 33 which may have an annular pressure equalizing groove 34 in communication with the inlet opening and an annular groove 35 in communication with the outlet opening and line. Valve member 38 includes an outer tubular portion 88 having an ex ternal diameter corresponding substantially tr the diameter of bore 33, and of suidcient length to alternately uncover the inner ends of inlet and outlet openings 3l and 32 upon shifting movement longitudinally of the tool. For instance, in the Fig. l or discharge position, the valve member is disposed across opening 3| to close 01T the inlet opening, but has uncovered discharge opening 32. In the Fig. 2 or intake position, the valve member has moved downwardly to close off opening 32 while uncovering opening 3|.

Valve member 36 includes also a plurality of angularly spaced web portions 43 extending in wardly from portion 88 and carrying a first reduced portion 90 disposed about and spaced from the piston rod to retain packing 45 for preventing fluid leakage from the cylinder about the rod.

Portion 98 terminates downwardly in a tubular.

portion 44 of a further reduced diameter such as to be movably carried about the piston rod. This lower portion extends through opening 99 in the partition 39 to permit upward shifting of the valve member from beneath the partition.

Stop ring 31 limits upward movement of the valve member, and engagement of shoulder 3S on the valve member with partition 39 limits downward movement. Spring pressed ball detent ed cooperates with annular external grooves 4i an 42 on the valve member to releasably retain that member in intake and discharge positions.

, Coil spring 46, sleeve 41 and washer 48 are movably carried about piston rod vI1 above the valve member, the spring and sleeve being successively engageable by the piston upon downward or advancing movement to shift the valve member downwardly as the piston reaches its lowermost position. As the piston moves down, the spring is rst compressed without any effect on the valve, which is maintained in the up position by ball detent 4/0. The piston then en A gages sleeve 41 which initiates movement of the valve and the shifting motion is rapidly completed by the compressed spring, once ball 49 is out of groove 42. Beneath partition 39, piston rod I1 presents an upwardly facing shoulder 49 for shifting the valve member upwardly as th' piston and rod reach their uppermost position. This shifting is effected through washer 59, spring V5I and washer 52 which engages the lower extremity of the reduced diameter portion 44 of the valve member.' Upward movement rst compresses the spring to an extent necessary for overcoming the tendency of the ball detent against movement, and then rapidly shifts the valve upwardly.

Body section I2 is threadedly secured to bodg.

. 4 section II at 53, disc 54 being disposed trans-- versely between the two sections to maintain packing 55 in the illustrated position about portion 44 of the valve member and prevent uid leakage from the cylinder downwardly about the valve member. Tube 56 is secured in depending position within section I2. Coil spring 51 bear4 upwardly against ring 54 to urge cylindrical hammer I4 downwardly into striking engagement with tool element I5. Tubular insert 58 may be secured within the lower portion of body section I2 to serve as a vertical guide for the hammer and as a stop limiting downward expansion of spring 51.

The lowermost body section I3 is threadedly carried by section I2 at 59 and presents an upper bore 69 and a lower reduced diameter bore 6I. The upper anvil portion or head 62 of tool element I5 is vertically movable within bore 69 and is urged upwardly within that bore by spring 63. Depending pin portion 64 of the tool element extends through bore 6l and carries at its lower end a chisel or other work engaging instrument 65. Engagement of instrument 65 with bottom shoulder 66 on body section I3 limits upward movement of the tool element.

Means I9 for interconnecting hammer I4 and piston rod I1 during retraction of the piston comprise pin 61 extending upwardly from the center of the hammer and socket assembly 68 carried at the lower end of the piston rod. Pin 61 is annularly recessed at 69 to form head 10. Assembly 68 includes a socket 1I secured to the lower end of the piston rod by pin 12 and presenting a downwardly facing bore 13 adapted to receive pin At angularly spaced locations, socket 1I is provided with a plurality of openings 14, each adapted to retain a ball 15, the openings having an inner diameter at 9| slightly smaller than the balls to prevent movement of the balls inwardly beyond the position of Fig. 2. Sleeve 16 is carried about the socket and is movable longitudinally of the socket to control the radial positions of the balls. For this purpose, sleeve 16 is provided with a pair of cylindrical inwardly facing bores 11 and 18, the former having a greater diameter than the latter, and an annular wedge shaped bore 19 extending between the two cylindrical bores. Thus, as will be understood, when sleeve 16 is in the position of Fig. l, balls 15 are permitted by bore 11 to move outwardly to the illustrated position and thus out of blocking relation with respect to head 10 of the hammer pin. Upon upward movement of the sleeve relative to the socket to the position of Fig. 2, wedge surface 19 moves the balls radially inwardly and cylindrical surface 18 maintains the balls in the inner position to prevent removal of pin 61 from the socket. Ball detent 80, urged outwardly by spring 84, cooperates with annular grooves BI and 82 in the sleeve to releasably maintain the sleeve Vin the position of either Fig. l or Fig. 2. Pin 83 is urged by spring 84 in a direction the reverse of that in which ball 89 is urged, and engages keyway on the inner surface of sleeve 18 to maintain the sleeve against rotation after initial assembly of the interconnecting mechanism.

Fig. 1 illustrates the positions of the various parts immediately after complete retraction or upward movement of the piston and hammer and after release of the hammer for a downward striking blow. The hammer is moving downwardly in advancing direction as shown by arrow 92 under the influence of coil spring 51. At the lower end of this travel, the hammer strikes the upper anvil end 62 of tool element I5 to impart a powered blow to the work engaging instrument 65. In Fig. 1, valve member 36 is in discharge position in which discharge opening 32 is in communication with the cylinder below piston I6 to permit escape of the fiuid. Consequently, spring 23 is free to urge the piston and piston rod downwardly following hammer I4, forcing the liquid beneath the piston out through discharge connection 30.

As the piston and rod reach the lower limit of their travel, sleeve 'I6 of the interconnecting mechanism engages the upper surface of the hammer and is shifted upwardly relative to socket 'Il to the position of Fig. 2 to displace balls inwardly into blocking relation with head 10 of the hammer pin. During the same downward movement, piston I6 first engages and compress-:s spring 46 and then engages sleeve 41 to shift the valve member downwardly to the intake position of Fig. 2 in which the exhaust opening is closed and the intake opening is uncovered. After the valve has been thus shifted, pressure fluid enters the cylinder through intake line 29 and urges piston I6 upwardly in retracting direction. Balls 'i5 engage the lower side of head l!) on the pin to interlock the hammer and piston rod and cause retraction of the hammer corresponding to the powered retraction of the piston. Fig. 3 illustrates the positions of the various parts during such retraction.

As the piston and hammer reach retracted position, sleeve 16 engages tube 55 and is shifted downwardly to the position of Fig. 1 to release the hammer for another powered blow. During the nal part of the retracting movement, spring 5l is compressed, and, upon the rapid upward movement of the piston and rod after release of the hammer, spring 5i effects upward movement of the valve member from the position of Fig. 2 to that of Fig. l, as a result of force exerted by the spring against tubular portion 38 of the valve member. The cycle is then repeated, and the tool mechanism thus acts to produce a rapid succession of powered blows against the upper end of tool element l5, which in turn imparts corresponding blows to the work.

To provide automatic means for stopping operation of the described impact tool, the tool'element and spring are designed in a relation such that, as long as the operator rests the weight of the entire tool on the tool element, the hammer operates as described, but if the tool is raised, the piston operates without effect on the tool element. This result is achieved by employing a spring E0 of such design as to permit slight downward movement of the tool element by its own weight upon raising the weight of the tool. This permits hammer I4 to remain in a lower advanced position than that of Fig 2, and the piston then does not move socket 'H sufficiently low for balls 'I5 to interengage with the hammer pin. Sleeve 58 limits downward expansion of power spring 51, which may be preloaded or under compression even in the Fig. 2 condition, and thus prevents spring 51 from following the hammer to a position lower than that of Fig. 2 to interfere with the critical relationship between the tool weight and the design of spring 60. Under these conditions, the piston operates in the usual reciprocating manner but without movement of the hammer.

I claim:

1. A tool of the character described, comprising a tool body, a hammer carried by said body for reciprocal movement in advancing and retracting directions, an actuating element carried by saidbody for reciprocal movement in said directions, means for hydraulically moving said element in retracting direction, a rst yielding means urging said hammer in said advancing direction, av second yielding means urging said actuating element in said advancing direction, valve means operable to admit pressure uid into engagement with said actuating element upon advancement of said ele;4 ment, to a predetermined advanced position and until said element is moved by said fluid to a predetermined retracted position, said valve means being operable upon such movement of the element to said retracted position to close ofi' the suuply of pressure fluid to said element and permit discharge of accumulated fluid to permit advancement of said element under the iniluence of second yielding means, means operable tointerconnect said hammer and element so that the defined fluid pressure actuated retraction of said element effects a corresponding retraction of said hammer against the tendency of said rst yieldinfr means, and means operable to release said interconnection after retraction of said element to a position near said retracted position to thereby permit advancing movement of said hammer under the influence of said rst yielding means.

2. A tool of the character described, comprising a tool body, a hammer carried by said body for reciprocal movement in advancing and retracting directions, yielding means urging saidv hammer in said advancing direction, a hydraulic cylinder in said body, a power piston within said cylinder hydraulically movable in said retracting direction', means operable to interconnect said hammer and piston so that retracting movement of said piston eifects corresponding retraction of said hammer against the tendency of said yielding means, and means operable to then release said interconnection to permit movement of said hammer in said advancing direction under the inliuence of said yielding means.

3. A tool of the character described, comprising a tool body, a hammer carried by said body for reciprocal movement in advancing and retracting directions, yielding means urging said hammer in. said advancing direction, a hydraulic cylinder in said body, a power piston within said cylinder hydraulically movable in said retracting direction, a piston rod carried byfsaid piston and movable therewith, means operable to interconnect said hammer and rod so that the deiined retracting movement of said piston effects corresponding retraction of said hammer against the tendency of said yielding means, and means operable to then release said interconnection to permit advancing movement of said hammer under the influence of said yielding means.

4. A tool of the character described, comprising a tool body, a hammer carried by said body for reciprocal movement in advancing and retracting directions, a rst yielding means urging said ham'- mer in said advancing direction, a hydraulic cylinder in said body, a power piston within said-cylinder hydraulically movable in said retracting direction to a retracted position, second yielding means urging said piston in advancing direction and operable to return said piston in said advancing direction after its hydraulically powered retraction to said predetermined position, means operable to interconnect said hammer and pist0n so that the defined retracting movement of said piston effects corresponding retraction of said hammer against the tendency of said rst 7 yielding means, and means operable as said pistn nears said retracted position to release said interconnection to permit advancement of said hammer under the influence of said rst yielding means..

5. A tool of the character described, comprising a tool body, a hammer element carried by said body for reciprocal movement in advancing and retracting directions, an actuating element reciprocally movable in said directions, means for hydraulically moving said actuating element in retracting direction, yielding means urging said hammer element in advancing direction, and means operable to interconnect said elements upon movement of said actuating element to a predetermined advanced position and to release said interconnection upon movement of said actuating element to a predetermined retracted position, said interconnecting means comprising a projection carried by one of said elements and presenting a transverse flange, a transversely movable ball carried by the other of said elements, and means for displacing said ball into blocking relation with respect to said flange to thereby interlock the elements upon arrival of said actuating element at said advanced position and operable to release said ball for movement out of such blocking relation as said actuating element reaches said retracted position.

6. A tool of the character described, comprising a tool body, a hammer element carried by said body for reciprocal movement in advancing and retracting directions, an actuating element reciprocally movable in said directions, means for hydraulically moving said actuating element in retracting direction, yielding means urging said hammer element in advancing direction, means operable to interconnect said elements upon movement of said actuating element to a predetermined advanced position and to release said interconnection upon movement of said actuating element to a predetermined retracted position,said interconnecting means comprising a headed pin carried by said hammer, a socket carried by said actuating element and adapted to receive said pin, the wall of said socket containing a plurality of angularly spaced openings, a ball retained Within each of said openings and adapted for inward movement into blocking relation with the head of said pin, and means operable to displace said balls into said blocking relation to thereby interlock the elements upon arrival of said actuating element at said advanced position and operable to release said balls for movement out of such blocking relation as said actuating element reaches said retracted position.

7. A tool c1" the character described, comprising a tool body, a hammer element carried by said body for reciprocal movement in advancing and retracting directions, an actuating element reciprocally movable in said directions, means for hydraulically moving said actuating element in retracting direction, yielding means urging said hammer element in advancing direction, means operable to interconnect said elements upon movement of said actuating element to a predetermined advanced position and to release said interconnection upon movement of said actuating element to a predetermined retracted position, said interconnecting means comprising a headed pin carried by said hammer, a socket carried by said actuating element and adapted to receive said pin, the wall of said socket containing a plurality of angularly spaced openings, a ball retained within each of said openings and adapted for inward movement into blocking relation with the head of said pin, a tubular member movably carried about said socket and presenting a pair of inwardly facing cylindrical surfaces at different radii connected by an annular wedge surface, said tubular member being engageable with said hammer and longitudinally shiftable thereby in one direction relative to said socket and into interlocking position upon movement of said actuating element to said advanced position, said longitudinal shifting causing said Wedge surface to displace said balls into blocking relation with said head for maintenance in said relation by the cylindrical surface having the Smaller radius, and a stop element carried by said body for engaging and shifting said member in the other direction longitudinally of said socket and into released position as said actuating element reaches said retracted position to permit movement of said balls to an outer position into engagement with the other cylindrical surface and consequent release of said hammer element.

8. A tool of the character described, comprising a tool body, a hammer element carried by said body for reciprocal movement in advancing and retracting directions, an actuating element reciprocally movable in said directions, means for hydraulically moving said actuating clement in retracting direction, yielding means urging said hammer element in advancing direction, means operable to interconnect said elements upon movement of said actuating element to a predetermined advanced position and to release said interconnection upon movement of said actuating element to a predetermined retracted position, said interconnecting means comprising a headed pin carried by said hammer, a socket carried by said actuating element and adapted to receive said pin, the wall of said socket containing a plurality of angularly spaced openings, a ball retained within each of said openings and adapted for inward movement into blocking relation with the head of said pin, a tubular member movably carried about said socket and presenting a pair of inwardly facing cylindrical surfaces at diierent radii connected by an annular wedge surface, said tubular member being engageable with said hammer and longitudinally shiftable thereby in one direction relative to said socket and into interlocking position upon movement of said actuating element to said advanced position, said longitudinal shifting causing said wedge surface to displace said balls into blocking relation with said head for maintenance in said relation by the cylindrical surface having the smaller radius, a stop element carried by said body for engaging and shifting said member in the other direction longitudinally of said socket and into released position as said actuating element reaches said retracted position to permit movement of said balls to an outer position into engagement with the other cylindrical surface and consequent release of said hammer element, and detent means operable to releasably retain said valve member in either of said interlocking or released positions.

9. A tool ci the character described, comprising an elongated vertically extending tubular body, a partition disposed transversely across said body intermediate its ends to form an upper hydraulic cylinder and a lower hammer chamber, a power piston disposed within said cylinder above said partition, said piston being reciprocable between a lower advanced position and an upper retracted position, yielding means disposed above said piston and urging said piston downwardly, valve means operable to alternately admit pressure into said cylinder beneath said piston and then permit its discharge to thereby cause powered vertical reciprocation of said piston, a piston rod connected to said piston and extending downwardly within said body through an opening in said tranverse partition and into said hammer chamber, a hammer vertically reciprocable within said chamber between an upper retracted position and a lower advanced position, a work engaging tool element movably mounted at the bottom of said body for limited vertical reciprocation and having an upper anvil end engageable by said hammer in said advanced position, second yielding means urging said hammer downwardly, means operable to interconnect said piston rod and hammer during upward movement of said piston whereby said hammer is carried upwardly against the tendency of said second yielding means, and means operable to release said interconnecting means as said piston nears its uppermost position to 10 permit downward movement of said hammer under the influence of said second yielding means to strike said anvil end of said tool element a powered blow.

ALBERT L. STONE.V

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

UNITED STATES PATENTS