US3529511A - Percussive tools utilizing a reciprocating differential area piston - Google Patents

Percussive tools utilizing a reciprocating differential area piston Download PDF

Info

Publication number
US3529511A
US3529511A US698624A US3529511DA US3529511A US 3529511 A US3529511 A US 3529511A US 698624 A US698624 A US 698624A US 3529511D A US3529511D A US 3529511DA US 3529511 A US3529511 A US 3529511A
Authority
US
United States
Prior art keywords
piston
cylinder
fluid
pressure
valve
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US698624A
Other languages
English (en)
Inventor
Anthony Edward Walter Last
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BSP International Foundations Ltd
Original Assignee
British Steel Piling Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Steel Piling Co Ltd filed Critical British Steel Piling Co Ltd
Application granted granted Critical
Publication of US3529511A publication Critical patent/US3529511A/en
Assigned to BSP INTERNATIONAL FOUNDATIONS LIMITED reassignment BSP INTERNATIONAL FOUNDATIONS LIMITED CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: BRITISH STEEL PILING COMPANY LIMITED, THE
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
    • B25D9/14—Control devices for the reciprocating piston
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
    • B25D2250/171—Percussive pulling action of tools for extraction of elements

Definitions

  • a valve controls the supply of fluid to the cylinder such that the lower, smaller end area of the piston is subjected to fluid pressure to lift the piston and the valve then allows pressure fluid to reach the other end of the piston during its upward stroke by putting both ends of the piston into communication with each other.
  • said other end enters a sealed space whereby the pressure acting on it builds up rapidly causing an accelerated reversal into the impact stroke of the piston.
  • exhaust ports are uncovered to release pressure fluid acting on said other side of the piston.
  • This invention relates to percussive tools arranged to be operated by compressible fluids. in particular compressed air.
  • a differential area ram piston is slidable in a cylinder having bores in its walls which form fluid inlets at opposite ends while a control valve provides a sequential connection of these bores to air under pressure reciprocating the piston in the cylinder.
  • the smaller area side of the piston is at the bottom of the cylinder when at rest and in the cycle of movement.
  • the valve first delivers compressed air to that side to lift the piston.
  • the valve next places both sides of the piston'in communication with each other so that the piston slows down and after reaching the end of its upward stroke it falls to provide a working impact.
  • the compressed air above the piston is released to atmosphere shortly before the piston impact at the bottom of its stroke.
  • a disadvantage of this known arrangement is that the speed of movement of the piston is limited by the space that must be allowed for the reversal of its movement at the top of its stroke where the change of velocity is relatively slow since it is determined by the imbalance between the inertia forces on the piston and the net pressure force resulting from the different areas at the top and bottom faces of the piston.
  • One result of this is that the cycle frequency at which the piston operates is restricted.
  • a percussive tool operable by a compressible fluid and comprising a differential area ram piston slidable in a cylinder having fluid ports at opposite end regions, valve means being arranged to deliver pressure fluid to the smaller area side of the piston to urge it from its associated end of the cylinder and to deliver pressure fluid to the larger area side of the piston as the piston approaches the opposite end of the cylinder to reverse the piston into an impact stroke of its cycle of motion, exhaust means being arranged to release pressure fluid from the cylinder during said impact stroke, the fluid port associated with said larger area side of the piston being spaced from its endof the cylinder whereby travel of the piston into said end region seals off said port and creates a fluid buffer zone in said region accelerating reversal of the piston motion.
  • sealing of the port is completed when the piston has travelled through substantially no more than 80 percent of the cylinder free space.
  • the increase of pressure at said opposite end of the cylinder is achieved by interconnecting the fluid ports as the piston approaches said opposite end to equalise pressures at both ends of the cylinder.
  • the valve means may itself comprise a reciprocable piston having differential area faces, the smaller area face being in communication with fluid line pressure and the larger area face being in communication with said other end of the cylinder.
  • the cylinder inlet conduit associated with said smaller area side of the ram piston can then extend to a valve chamber within which said body is reciprocable, said conduit being located axially intermediate the connections from said chamber to the pressure line and to the port for said other end of the cylinder whereby movement of the valve body brings said conduit into alternate communication with each of said two connections.
  • means comprising a passage connected to the fluid pressure line and communicating with said opposite end of the cylinder for starting the motion of the ram piston on the stroke away from said opposite end of the cylinder.
  • FIG. 1 is a sectional elevation of the hammer
  • FIG. 2 is a corresponding section to a larger scale of the distributing valve of the hammer.
  • the hammer comprises a rectangular section casing 2 having a main cylindrical bore 4 forming a pressure cylinder within which a piston 6 is reciprocable.
  • the limits of the pressure cylinder are defined by a sealing disc 20 at its upper end secured by a circlip 19 and by a closure ring 10 at its lower end secured by a circlip 9.
  • the piston 6 has an integrally formed impact stem 12 that sealingly slides in a metallic gland ring (not shown) clamped within the closure ring 10.
  • the top plate 2Q comprises a suspension eye 2l and at the bottom end of the casing an anvil block 22. that is struck by stem 12 when the pistondescends. is attached to the casing by a wire sling (not shown) passing through lower hole 21' of the suspension eye.
  • Reciprocation of the piston is actuated by compressedair which can reach the cylinder by upper and lower inlet conduits 24. 26 respectively.
  • the conduit 24 is secured in position in a recess 23 of the casing by a block 25 bolted to the casing and bearing on the curved end of the conduit.
  • Pairs of exhaust conduits 28 each equidistant from the sectional. plane of FIG. I, extend through opposite sides of the casing intermediate the length of the cylinder, their position being such that they are uncovered by the piston 6 shortly before it reaches the bottom of its stroke.
  • valve 30 shown in more detail in FIG. 2.
  • This comprises a block 32 having a vertical bore 33 that forms a cylindrical chamber 34.
  • a counterbore 35 at the top of the bore 33 receives the open end of the conduit 24 which seats against a resilient buffer ring 37.
  • An annular recess 38 intermediate the length of the chamber 34 communicates with the conduit 26 through an opening 39.
  • a tapping 40 on the block 32 receives a connection 41 (FIG. I) from a source of compressed air and communicates with the chamber 34 through an annular recess 42 immediately above a reduced diameter bore 36 continuing downwardly from the bore 33.
  • the valve has a double-headed piston 44 comprising a smaller diameter lower head 45 sealing with the lower bore 36 and a larger diameter upper head 46 sealing against the bore 33 forming the chamber 34.
  • the two sides of the piston thereby have different areas exposed to the pressures within the chamber and, similarly to the main hammer piston 6, the smaller face area is to the underside of the piston.
  • a resilient buffer 52 is secured in a counterbore 50 at the bottom of the bore 36 to limit the downwards displacement of the piston.
  • the sequence of operation of the hammer mechanism can be considered from the position shown in the drawing where the hammer piston 6 is at the bottom of its stroke while the valve piston 44 is at the top of its stroke.
  • the upper end of the hammer cylinder is then in communication with atmosphere through the exhaust outlets 28.
  • the tapping 40 is connected to a line carrying compressed air, in this example at a pressureof I05 lbs. per square inch absolute, and this is transmitted through the chamber 34 and opening 39 to the underside of the hammer piston.
  • the valve piston 44 is supported in its uppermost position by the net pressure force on the different areas of its upper and lower heads.
  • valve piston Depression of the valve piston brings its upper head 46 below the annular recess 38 and therefore the cylinder spaces on both sides of the hammer piston 6 are placed in communication with each other, through conduit 24, connecting passages in valve 30 and to conduit 26, and their pressures are equalised at some lbs. per square inch absolute.
  • the hammer operates as a pile driver but a feature of the design is its ability to be used alternatively to extract piles.
  • the unit is, of course, inverted and is connected to the pile through wire bridles in a conventional manner.
  • the hammer piston Before being connected to line pressure, however, the hammer piston will now be in the opposite end position to that shown in the drawing and no movement will take place if pressure is simply applied through the tapping 40.
  • an auxiliary tapping 48 is provided on the line to the top of the cylinder with which it communicates through a nonretum valve 49.
  • a percussive tool operable by a compressible fluid and comprising in combination, a cylinder, a ram piston slidable within the cylinder and having different area ends within the cylinder, fluid inlet ports arranged at opposite end regions of the cylinder.
  • valve means for controlling the flow through said ports, and conduit means connecting the ports to the valve means, said valve means being arranged to deliver pressure fluid to the smaller area end of the cylinder and to bring said ports into communication with each other through said conduit means to apply fluid pressure to the larger area end of the piston as the piston approaches the opposite end of the cylinder to reverse the piston into an impact stroke of its cycle of motion.
  • exhaust means in the cylinder being arranged to release pressure fluid from the cylinder during said impact stroke, the fluid inlet port associated with said larger area end of the piston being spaced from its end of the cylinder whereby travel of the piston into said end region seals off said inlet port and creates a fluid buffer zone in said region accelerating reversal of the piston motion.
  • a percussive tool operable by a compressible fluid comprising in combination. a cylinder. a ram piston slidable within the cylinder and having different area ends within the cylinder. fluid ports arranged at opposite end regions of the cylinder. valve means in communication with said ports and being arranged to deliver pressure fluid to the smaller area end of the piston to urge it from its associated end of the cylinder and to deliver pressure fluid to the larger area end of the piston as the piston approaches the opposite end of the cylinder to reverse the piston into an impact stroke of its cycle of motion. exhaust means in the cylinder being arranged to release pressure fluid from the cylinder during said impact stroke.
  • valve means comprises a cylinder, a piston reciprocable therein having differential area end faces, the smaller area face being in communication with fluid line pressure and the larger area face being in communication with the fluid port in the region of said cylinder opposite end, said valve piston being displaceable to interconnect the cylinder fluid ports as the ram piston travels towards said opposite end of the cylinder so that pressures on both sides of the ram piston are equalized, during the upward motion of the ram piston.
  • valve piston comprises a pair of heads at opposite ends and different area bores are formed in the valve cylinder to receive the respective heads, fluid line pressure being directed to the space between the piston heads and a fluid conduit being provided from the outer end of the larger area head to said cylinder opposite end region.
  • a percussive tool operable by a compressible fluid comprising in combination, a cylinder, a ram piston slidable within the cylinder and having different area ends within the cylinder, fluid ports arranged at opposite end regions of the cylinder, valve means in communication with said ports and being arranged to deliver pressure fluid to the smaller area end of the piston to urge it from its associated end of the cylinder and to deliver pressure fluid to the larger area end of the piston as the piston approaches the opposite end of the cylinder to reverse the piston into an impact stroke of its cycle of motion, exhaust means in the cylinder being arranged to release pressure fluid from the cylinder during said impact stroke, the fluid port associated with said larger area end of the piston being spaced from its end of the cylinder whereby travel of the piston into said end region seals off said port and creates a fluid buffer zone in said region accelerating reversal of the piston motion, said valve means comprising a cylinder having two different area bores in series, a valve piston reciprocable in the cylinder and having a pair of heads spaced at opposite
  • a percussive tool according to claim 6 wherein said fluid conduit comprises a main portion located co-axially with the valve cylinder bores and a curved transition portion extending therefrom to said cylinder end region.
  • l0.'A percussive tool operable by a compressible fluid and comprising in combination. a cylinder. a ram piston slidable within the cylinder and having different area ends within the cylinder, fluid ports arranged at opposite end regions of the cylinder. valve means in communication with said ports and being arranged to deliver pressure fluid to the smaller area end of the piston to urge it from its associated end of the cylinder and to deliver pressure fluid to the larger area end of the piston as the piston approaches the opposite end of the cylinder to reverse the piston into an impact stroke of its cycle of motion, exhaust means in the cylinder being arranged to release pressure fluid from the cylinder during said impact stroke.
  • starting means comprising a fluid conduit bypassing the valve means and interconnecting the fluid pressure line with the said opposite end of the ram cylinder through non-return flow means to displace the piston from said opposite end of the cylinder independently of the valve means. whereby operation of the tool in an inverted position can be initiated.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Percussive Tools And Related Accessories (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
US698624A 1967-01-19 1968-01-17 Percussive tools utilizing a reciprocating differential area piston Expired - Lifetime US3529511A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2831/67A GB1212975A (en) 1967-01-19 1967-01-19 Improvements in or relating to percussive tools

Publications (1)

Publication Number Publication Date
US3529511A true US3529511A (en) 1970-09-22

Family

ID=9746766

Family Applications (1)

Application Number Title Priority Date Filing Date
US698624A Expired - Lifetime US3529511A (en) 1967-01-19 1968-01-17 Percussive tools utilizing a reciprocating differential area piston

Country Status (4)

Country Link
US (1) US3529511A (en))
BE (1) BE709642A (en))
DE (1) DE1983498U (en))
GB (1) GB1212975A (en))

Also Published As

Publication number Publication date
DE1983498U (de) 1968-04-11
BE709642A (en)) 1968-05-30
GB1212975A (en) 1970-11-18

Similar Documents

Publication Publication Date Title
US5085284A (en) Hybrid pneumatic percussion rock drill
US4042311A (en) Pump fluid motor carrying spool valve for distributor valve actuation
US3908767A (en) Percussion tool
US4034817A (en) Impact tool
KR100573011B1 (ko) 유압식 충격 장치
US5752571A (en) Apparatus for generating impacts
US3735823A (en) Impact motive implement
US3425498A (en) Fluid actuated vibrator devices
US3657968A (en) Pneumatic stapling device
US2403582A (en) Power hammer
US3298447A (en) Control of variable-stroke power hammers
US2748751A (en) Fluid actuated power hammers
US3529511A (en) Percussive tools utilizing a reciprocating differential area piston
US4450920A (en) Hydraulic reciprocating machines
US2789540A (en) Compound hammer
US4256187A (en) Impact tool with hydraulic cocking mechanism
US4006665A (en) Percussion tool
US3146835A (en) Hammer for driving piles by impact or by vibrating action
JPH03170275A (ja) ピストン振動数制御装置
US1077469A (en) Power-driven hammer.
US3332503A (en) Double-acting steam-air hammer, in particular for pile immersion
US3486568A (en) Hydraulic impact apparatus
US2969771A (en) Power hammer
JP2675247B2 (ja) ハンマー装置
GB2069902A (en) Submersible hammer

Legal Events

Date Code Title Description
AS Assignment

Owner name: BSP INTERNATIONAL FOUNDATIONS LIMITED

Free format text: CHANGE OF NAME;ASSIGNOR:BRITISH STEEL THE, PILING COMPANY LIMITED;REEL/FRAME:004478/0278

Effective date: 19710824