GB2114495A - Impact tool - Google Patents

Impact tool Download PDF

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Publication number
GB2114495A
GB2114495A GB08231001A GB8231001A GB2114495A GB 2114495 A GB2114495 A GB 2114495A GB 08231001 A GB08231001 A GB 08231001A GB 8231001 A GB8231001 A GB 8231001A GB 2114495 A GB2114495 A GB 2114495A
Authority
GB
United Kingdom
Prior art keywords
housing
ram
reduced
impact
anvil
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.)
Granted
Application number
GB08231001A
Other versions
GB2114495B (en
Inventor
Tadao Tanoi
Naoya Kurihara
Toshio Mikiya
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.)
Nitto Kohki Co Ltd
Original Assignee
Nitto Kohki 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
Priority to JP1981161186U priority Critical patent/JPS617908Y2/ja
Application filed by Nitto Kohki Co Ltd filed Critical Nitto Kohki Co Ltd
Publication of GB2114495A publication Critical patent/GB2114495A/en
Application granted granted Critical
Publication of GB2114495B publication Critical patent/GB2114495B/en
Expired legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25DPERCUSSIVE TOOLS
    • B25D9/00Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
    • B25D9/06Means for driving the impulse member
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25DPERCUSSIVE TOOLS
    • B25D17/00Details of, or accessories for, portable power-driven percussive tools
    • B25D17/02Percussive tool bits
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25DPERCUSSIVE TOOLS
    • B25D17/00Details of, or accessories for, portable power-driven percussive tools
    • B25D17/06Hammer pistons; Anvils ; Guide-sleeves for pistons
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25DPERCUSSIVE TOOLS
    • B25D17/00Details of, or accessories for, portable power-driven percussive tools
    • B25D17/08Means for retaining and guiding the tool bit, e.g. chucks allowing axial oscillation of the tool bit
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25DPERCUSSIVE TOOLS
    • B25D17/00Details of, or accessories for, portable power-driven percussive tools
    • B25D17/24Damping the reaction force
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25DPERCUSSIVE TOOLS
    • B25D2250/00General details of portable percussive tools; Components used in portable percussive tools
    • B25D2250/275Tools having at least two similar components
    • B25D2250/285Tools having three or more similar components, e.g. three motors
    • B25D2250/291Tools having three or more parallel bits, e.g. needle guns

Abstract

An impact tool including a housing 1 formed with a cylinder bore 3 and having a ram 2 positioned therein for generating an impact, and a front cylinder 4 including an anvil 13 and a tool holder 7 for a plurality of tools 10 coaxially fixed relative to each other. The housing includes an outer circumference partially reduced to form a reduced portion 32. A cover sheath 35 is fitted on the outer circumference with a thickened portion 36 extending inwardly to cooperate with the reduced thickness portion of the housing but of less axial length to allow movement in an axial direction. Buffer springs 37 are respectively sandwiched between two ends of the thickened portion and two ends of the reduced portion and a return spring 11 is provided for returning the anvil. <IMAGE>

Description

SPECIFICATION Impact tool The present invention relates to an impact tool for chipping or grinding the surface of metal, stone or the like. More particularly, it relates to an improvement in an impact tool of the type in which a striking stroke is effected by the action of compressed air whereas the return stroke is effected by the elastic force of a spring, before the subsequent striking stroke.
Impact tools of the prior art have a defect in that they invite fatigue of the operator because they cannot be used for striking operations without being accompanied by vibrations.
In view of this defect inherent in the impact tools of the prior art, the present invention seeks to absorb shocks which might otherwise be transmitted to an axially movable holder. The present invention minimizes the generation of vibrations, which has been a problem with prior art tools, by fitting a holder on the outer circumference of the tool body and by attaching springs to the holder.
The present device also relates to a shock absorber to be used in an impact tool which is utilized to chip or grind the surface of a workpiece such as metal or stone.
In the situation when a chipping operation is to be carried out by the operator holding the impact tool in his/her hands with a chisel, carried on the leading end portion thereof, being driven by an impact generated by the action of a motor or compressed air so that the surface of a workpiece may be struck and ground by the tip of the chisel, both the shocks from inside the housing and the shocks from the workpiece surface are transmitted to the hands of the operator. The transmitted shocks accelerate fatigue or invite an interruption in blood circulation of the operator. This problem is a defect of prior art impact tools.
In view of the defect concomitant with the prior art, the present device is intended to absorb shocks which are to be transmitted to the body of the impact tool through the use of springs. The absorbed shocks are transmitted to a cover sheath by fitting a holder on the outer circumference of the tool body and by attaching springs to the holder.
The invention will become more fully understood from the following description given by way of example and with reference to the accompanying drawings, wherein: Figure 1 is a longitudinal sectional view of a first embodiment showing the impact tool before the striking operation; Figure 2 is a sectional view showing the impact tool after the striking operation; Figure 3 is a top plan view of a second embodiment showing the overall construction of the impact tool; Figure 4 is a section taken along Line A - A of Figure 3; Figure 5 is an end elevation as viewed from the rear end; and Figure 6 is a partially cut-away side elevation with the operating lever depressed.
The present device will first be described in connection with one embodiment thereof with reference to Figures 1 and 2.
A cylindrical housing 1 forms the body of an impact tool. A ram 2 is movably mounted to move in a forward direction by the action of compressed air.
The ram 2 is slidable back and forth in a cylinder bore 3 formed axially in the housing 1. A front cylinder 4 is fixed on the front of the housing 1 and is aligned with the axis of the cylinder bore 3. The front cylinder 4 has its leading end portion bent radially inward to form a spring seat 5 while leaving a large opening 6 at the center of the spring seat 5.
A tool receiver 7 has a generally C-shaped longitudinal section. The tool receiver 7 includes a base formed with ten or more tool holes 8 through which tool rods 10 extend. The tool rods 10 are each formed with a shank portion having a head 9.
Between the bottom face of the tool receiver 7 and the aforementioned spring seat 5, a return spring 11 is contained which urges the tool receiver 7 inward (i.e., rightwardly in the drawing).
An anvil 13 is interposed between the rear face of the base of the tool receiver 7 and the front face of the housing 1. The anvil 13 is mounted in the front cylinder 4 so as to slide back and forth. The impact of the ram 2 fitted in the cylinder bore 3 is transmitted by said anvil 13 to the tool rods 10. A reduced portion 13a formed at the leading end of the anvil 13 is impelled within the tool receiver 7 and directly hits the tool heads 9, when the tool rods 10 move inwardly. The anvil 13 also includes a rear flanged portion 13b for guiding the anvil 13 within the cylinder 4. A blind bore 15 extends axially into the ram 2 from the rear end of the ram. The ram 2 includes a generally intermediate portion formed with radial vent holes 16 and a rear end formed with a larger rear end portion 18 connected to the intermediate portion through a stepped portion 17.
A corresponding shoulder 19 acts as a stop engaged bythestepped portion 17 and is formed at a generally intermediate portion of the cylinder bore 3. The cylinder bore 3 is of larger diameter rearward of the shoulder 19.
A rear block 20 is fixed to the rear end of the housing 1. Avalve chamber 21 is formed in the block 20 and includes a control valve 23 mounted therein having a stem 22 protruding laterally to the outside from the intermediate portion of the block 20. An air inlet 24 is formed through the rear end of the block 20, and a communication passage 25 provides communication between the air inlet 24 and the other end of the block 20 through the valve chamber 21. Air supply passages 26 are formed axially in the housing 1 and are in communication with the passage 25.
A rearward facing shoulder 30 is formed near the front end of the housing 1. A forward facing shoulder 31 is formed on the rear block 20. The housing 1 includes an outer circumferential surface formed with a reduced portion 32 disposed between the two stepped engagement portions 30 and 31.
A cover sheath 35 is fitted on the outer circumference of the front cylinder 4, the housing 1 and the rear member 20 and includes an inner circumference formed with a thickened engagement portion 36 which is engageable with the aforementioned reduced portion 32. The thickened engagement portion 36 is constructed to be shorter than the reduced portion 32. Buffer springs 37 are respectively sandwiched between the thickened engagement portion 36 and the stepped engagement portions 30 and 31 to urge the housing 1 and the cover 35 relative to each other in the axial direction.
The valve stem 22, which includes an upper end pivotally supporting a roller 39, protrudes from a C-shaped notched portion 38 formed in the rear portion of the cover sheath 35. An operating lever 40 is hinged to both sides of the rear portion of the cover sheath 35. Release ports 41 open into the larger portion of the cylinder bore 3 and are formed in symmetrical positions in the embodiment under consideration. The release ports 41 merge into the rear member 20 until they communicate with the outside of the impact tool body.
The operations of the aforementioned embodiment will be described hereinbelow.
The compressed air from outside is supplied to the air inlet 24 of the rear member 21. The tips of the chisel needles 10 are applied to a workpiece surface 50. When the operating lever 40 is subsequently depressed to open the control valve 23, the compressed air is fed through the communication passage 25 and the air supply passages to the inside of the cylinder bore 3.
At this time, if the impact tool is directed downward, the ram 2 is brought into its lefthand position, as viewed in the drawing, by its own weight. If, the air acts upon the stepped portion 17 of the ram 2, the ram 2 is moved rightward (i.e., backward), as viewed in the drawing.
When the air supply passage 26 and the vent holes 16 approach the state in which they communicate with each other, the compressed air spurts from the vent holes 16 into the inside of the blind hole 15 thereby to boost the pressure in the blind hole 15, i.e., the back pressure on the ram 2. As a result, the ram 2 is abruptly forced forward to strike the anvil 13. The momentum of the ram 2 is transmitted through the impact at that time to the needle receiver 7 by way of the reduced portion 13a of the anvil 13 thereby to move the needle receiver 7 forward and to hit the needle heads 9 of the chisel needles 10 extending through the needle receiver 7 so that the chisel needles 10 are driven forward to effect the chiping operations or the like.When the ram 2 comes to its foremost position, the blind hole 15 communicates with the release ports 41 through the vent holes 16so that the return spring 11 then moves the needle receiver 7 backward. On the other hand, the ram 2 has its stepped portion subjected to the pressure of the compressed air similarly to the aforementioned state so that it is moved back by the action of the compressed air for the subsequent striking operation.
During this operation both the shock established when the ram 2 hits the needle receiver 7 through the anvil 13, and the shock established when the tips of the chisel needles 10 strike the workpiece surface 50 are transmitted to the housing 1. However, the shocks are transmitted as gentle vibrations through the springs 37 to the cover sheath 35 which is fitted on the outer circumference of the housing 1 as to move in the axial direction. As a result, fatigue to the operator holding the cover sheath 35 is reduced.
The second embodiment of the present device, namely a shock absorber for an impact tool, will now be explained with reference to Figures 3 to 6.
Afirst lever 2 is hinged to the rear portion of a housing 1 and also acts as a handle. When the lever 2 is depressed to open a control valve 3, air from outside spurts from an air inlet 4 through a control valve 3 into an air supply passage 5, which is formed in the housing 1, to abruptly move forward a ram 7 which is fitted in a cylinder bore 6 formed to axially extend in the housing 1.
A chisel holder 13 is fitted in an axially movable manner in the open side of a pressure chamber 12 which is formed in the housing 1 having an opening 11 at its leading end. An anvil 14 is fitted at the back of the chisel holder 13 is so as to move in the axial direction. As a result, when the aforementioned ram 7 hits the anvil 14 so that the anvil 14 moves forward to hit the chisel holder 13, a chisel (although not shown) which is held by its holder 13 is carried to effect its chipping operation at a tip portion of the chisel.
A reduced portion 20 is formed at a generally intermediate portion of the outer circumference of the housing 1. First and second stepped portions 21 and 22 are formed on the outer circumference of the housing 1 at the two ends of the reduced portion 20.
A pair of notched grooves 24 are formed in the rear portion of the housing 1 in which the first lever 1 has a rear portion fitted and hinged by means of a pin 25. A cover sheath 35 is fitted on the outer circumference of the housing 1 so as to move in the axial direction. The cover sheath 35 is formed with a thickened portion 26 which protrudes radially inwardly from the inner circumference of the sheath 35 with a smaller axial length than that of the reduced portion 20 of the aforementioned housing 1 such that it is fitted on the reduced portion 20.
Elastic members 27 and 27', such as return springs, are elastically sandwiched between the two ends of the reduced portion 20 and the two ends of the thickened portion 26, respectively. A buffer sleeve 28 having a strong shock-absorbing action is mounted together with the elastic member 27 positioned at the side of the opening 11.
A notched portion 29 is formed at one end of the rear portion of the cover sheath 35 to allow the aforementioned control valve 3 to protrude therethrough. A second lever 37 coacting with the aforementioned first lever 2 includes a rear end hinged by means of a pin 31 to supports 30 which protrude from both sides of the rear end of that notched portion 29. The first lever 2 is positioned in the second lever 37 which in turn is made movable in the axial direction together with the cover sheath 35.
The operation of the second embodiment of the present invention is described hereinbelow.
As shown in Figure 6, the first and second levers 2 and 37 are depressed downward against the elastic force of an elastic spring 3a which forms a part of the control valve 3. The control valve 3 is opened so that the compressed air supplied from outside spurts into the cylinder bore 6 to abruptly move the ram 7 forward thereby to hit the chisel holder 13 through the anvil 14. Thus, the workpiece surface is ground and finished by the tip of the chisel which is carried by its holder 13.
Both the shock from the ram hitting the chisel holder through the anvil and the shock transmitted from the workpiece surface through the chisel are first transmitted to the housing 1. However, the operator holds the cover sheath 35 which is fitted on the outer circumfernce of the housing 1 so as to move back and forth. The aforementioned shocks are not transmitted as such to the hands of the operator.More specifically, since the elastic members 27 and 27' and the buffer sleeve 28 are respectively sandwiched between the two ends of the thickened portion 26, which is thickened to radially inwardly protrude from the inner circumference of the cover sheath 35, and the two ends of the reduced portion 20 which is formed in the housing, the axial shocks, which might otherwise be transmitted to said housing 1, are substantially absorbed by the elastic members 27 and 27' so that they are transmitted as gentle vibrations to the hands of the operator holding the cover sheath 35.
As had been described hereinbefore, according to the present device, the thickened portion 26, which is thickened to radially inwardly protrude from the inner circumference of the cover sheath 35 is fitted on the outer circumference of the housing 1 so as to move in the axial direction and is fitted on the reduced portion 20 which is formed at the outer circumference of the housing 1. The elastic members 27 and 27' are respectively sandwiched between the two ends of the thickened portion 26 and the two ends of the reduced portion 20. As a result, the sharp shocks in the axial direction, which might otherwise be transmitted to the housing 1, are absorbed through the elastic member 27 and 27' before they are transmitted to the cover sheath 35. Even if the operator holds the cover sheath 35 during chipping operations, he/she can be relieved from fatigue to improve his/her working performance.
The invention being thus described, it will be obvious that the same may be varied in many ways.
Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims (7)

1. An impact tool including a housing formed with a cylinder bore and having a ram positioned therein for generating an impact, and a front cylinder including both an anvil and a needle receiver for receiving a plurality of chisel needles being coaxially fixed relative to each other comprising: said housing including an outer circumference partially reduced to form a reduced portion; a thickened portion fitted on said reduced portion being formed to protrude radially inwardly from a cover sheath fitted on the outer circumference of said housing so as to move in an axial direction; buffer springs being respectively sandwiched between two ends of said thickened portion and two ends of said reduced portion; and a return spring for returning said anvil; said needle receiver and said ram being sandwiched between a front face of said anvil and a spring seat formed at a leading end of said front cylinder.
2. A shock absorber for use in an impact tool, comprising; a cylinder bore having a ram positined therein for generating an impact and a pressure chamber including both an anvil and a chisel holder for mounting a chisel being coaxiallyfitted in a housing; said housing including an outer circumference partially reduced to form a reduced portion; a thickened portion fitted on said reduced portion being formed to protrude radially inwardly from a cover sheath fitted on the outer circumference of said housing so as to move in an axial direction; and elastic members being respectively sandwiched between two ends of said thickened portion and two ends of said reduced portion.
3. An impact tool according to claim 1 or 2 wherein, a rear member is connected to the said housing and includes valve means for operatively supplying compressed air to a surface of said ram for reciprocating said ram to generate an impact.
4. An impact tool according to claim 3, wherein said housing and said cover sheath are cylindrical and are retained relative to each other by said rear member being operatively threaded to said housing.
5. An impact tool according to claim 1 or 2, wherein said ram includes a stepped down portion being in communication with a pressurized fluid during a returning motion and including an aperture therethrough for redirecting said pressureized fluid to reverse the direction of said ram and generate an impact on said anvil.
6. An impact tool according to claim 5, wherein said pressurized fluid is supplied through axial and radially extending passages in said housing.
7. An impact tool according to claim 3, and further including a release port for exhausting compressed air supplied to said ram to permit said ram to be moved in a returning motion.
GB08231001A 1981-10-30 1982-10-29 Impact tool Expired GB2114495B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP1981161186U JPS617908Y2 (en) 1981-10-30 1981-10-30

Publications (2)

Publication Number Publication Date
GB2114495A true GB2114495A (en) 1983-08-24
GB2114495B GB2114495B (en) 1985-03-20

Family

ID=15730219

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08231001A Expired GB2114495B (en) 1981-10-30 1982-10-29 Impact tool

Country Status (10)

Country Link
JP (1) JPS617908Y2 (en)
KR (1) KR850000633Y1 (en)
AU (1) AU543415B2 (en)
DE (1) DE3239174A1 (en)
FR (1) FR2519575B1 (en)
GB (1) GB2114495B (en)
IT (1) IT1224107B (en)
NO (1) NO154079C (en)
SE (1) SE457624B (en)
ZA (2) ZA8207544B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2141658A (en) * 1983-05-14 1985-01-03 Toshio Mikiya Multi-needle chisel tool
GB2142267A (en) * 1983-07-01 1985-01-16 Nilsson Goran Alfred Improvements in or relating to pressure medium operated needle hammers
EP0152376A1 (en) * 1984-02-09 1985-08-21 Von Arx Ag Percussion device
DE102014208064A1 (en) * 2014-04-29 2015-10-29 Heraeus Medical Gmbh Lavage system with a compressed gas engine and method for generating a spray
CN110475980A (en) * 2017-03-29 2019-11-19 日东工器株式会社 Prevent rotation annular component and compressed air driven from carving

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101291349B1 (en) * 2010-06-15 2013-07-30 삼성중공업 주식회사 Grinding apparatus and assembly thereof

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1018819B (en) * 1952-11-20 1957-11-07 Moenninghoff Maschf Pneumatic pick hammer with recoil damping by an elastic member
DE1672058U (en) * 1953-09-28 1954-02-18 Paul Wehrmann Hammer drill.
US2899934A (en) * 1956-01-19 1959-08-18 salengro
FR1348165A (en) * 1963-02-15 1964-01-04 Percussion tool
US3680643A (en) * 1969-03-01 1972-08-01 Nitto Kohki Co Fluid actuated tool having removable coil spring biasing means
CS149009B1 (en) * 1971-02-01 1973-05-24
DE2132854A1 (en) * 1971-07-01 1973-01-18 Linde Ag COMPRESSED AIR TOOL
DE2334817B2 (en) * 1972-10-03 1976-03-11 Hand operated compressed air impact machine
DE2403074C3 (en) * 1974-01-23 1978-10-26 Demag Ag, 4100 Duisburg
US3937055A (en) * 1974-11-06 1976-02-10 The United States Of America As Represented By The United States National Aeronautics And Space Administration Method of peening and portable peening gun
CH600993A5 (en) * 1976-06-30 1978-06-30 Arx Ag Percussion tool for cleaning surfaces

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2141658A (en) * 1983-05-14 1985-01-03 Toshio Mikiya Multi-needle chisel tool
GB2142267A (en) * 1983-07-01 1985-01-16 Nilsson Goran Alfred Improvements in or relating to pressure medium operated needle hammers
EP0152376A1 (en) * 1984-02-09 1985-08-21 Von Arx Ag Percussion device
CH655682B (en) * 1984-02-09 1986-05-15
DE102014208064A1 (en) * 2014-04-29 2015-10-29 Heraeus Medical Gmbh Lavage system with a compressed gas engine and method for generating a spray
DE102014208064B4 (en) * 2014-04-29 2015-12-03 Heraeus Medical Gmbh Lavage system with a compressed gas engine and method for generating a spray
US9964100B2 (en) 2014-04-29 2018-05-08 Heraeus Medical Gmbh Compressed gas motor for operation of a lavage system
CN110475980A (en) * 2017-03-29 2019-11-19 日东工器株式会社 Prevent rotation annular component and compressed air driven from carving
EP3604836A4 (en) * 2017-03-29 2020-12-30 Nitto Kohki Co., Ltd. Anti-rotation ring-shaped member, and compressed air-driven chisel

Also Published As

Publication number Publication date
NO154079B (en) 1986-04-07
KR840001977U (en) 1984-05-28
ZA8207544B (en) 1983-07-27
ZA827544B (en) 1983-07-27
IT1224107B (en) 1990-09-26
KR850000633Y1 (en) 1985-04-18
JPS5867670U (en) 1983-05-09
SE8205810D0 (en) 1982-10-13
JPS617908Y2 (en) 1986-03-11
FR2519575A1 (en) 1983-07-18
IT8283472D0 (en) 1982-10-29
DE3239174A1 (en) 1983-06-23
SE457624B (en) 1989-01-16
SE8205810L (en) 1983-05-01
NO823572L (en) 1983-05-02
FR2519575B1 (en) 1984-11-30
NO154079C (en) 1986-07-16
AU8933882A (en) 1983-05-19
GB2114495B (en) 1985-03-20
AU543415B2 (en) 1985-04-18

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Legal Events

Date Code Title Description
PE20 Patent expired after termination of 20 years

Effective date: 20021028