CA1094046A - Pneumatic percussion tool - Google Patents
Pneumatic percussion toolInfo
- Publication number
- CA1094046A CA1094046A CA304,662A CA304662A CA1094046A CA 1094046 A CA1094046 A CA 1094046A CA 304662 A CA304662 A CA 304662A CA 1094046 A CA1094046 A CA 1094046A
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- Canada
- Prior art keywords
- ram
- channel
- port
- nut
- reverse
- 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.)
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Abstract
PNEUMATIC PERCUSSION TOOL A pneumatic percussion tool comprising a hollow cylindrical body with a nut which covers the open end of the body and has longitudinal channels opening at one end on the internal cylindrical surface of the nut. Reciprocating under the pressure of compressed air inside said body is a stepped ram with an axial channel and at least one radial channel communicating with said axial channel. The front portion of the ram together with the walls of the body forms a reverse-stroke chamber which communicates periodically with the compressed air line through the channels of the ram. The surface of the ram large-diameter step is provided with longitudinal channels for communication of the reverse-stroke chamber with the atmosphere. The external surface of the ram small-diameter step, the internal surface of the body, the face of the nut and the face of the ram large-diameter step form an annular space which is put periodically in communication with the atmosphere whilst the portion of the ram small-diameter step interacting with the nut has at least one radial port arranged so that during the movement of the ram towards the front end of the body said annular space is filled with compressed air through the radial port of the ram and the longitudinal channel of the nut.
Description
~ he present i~ventio~ re~ates to percu~sion devices, and more particularly, to pneumatic percussion tools.
~ he invention will be used to the best advantage for driving wells through compacted ground.
It can also be useful for dri~i~g pipes, èarthing electrodes, wooden and metallic slutted piles into the ground.
Enown in the prior art are pneumatic percussion tools, for example for holi~g wells in the ground consisting of a hollo~ cylindrical body accom~odating a stepped ram provi-ded with a space in the tail portion, and a port. ~here also is a nut which covers the space of the body and mounts an air-distributing meehanism. ~he air-distributing mechanism is made in the form of a stepped branch pipe rigidly fixed by the tail portion to the nut. The front bigger step of the branch pipe is mounted inside the ram.
When the compresse~ air supply is turned on, ,the step-ped ram starts reciprocating and, being in the forward position strikes the body thus driving the tool into the ground. ~he compressed air is constantly fed into the rear working chamber formed by the walls of the ram and branch pipe. When the ram occupies the forward position the compressed air flows through the port in the ram into the reverse-stroke cham~er a~d, owin~ to the fact that the Qur~ace area of the ram dire¢ted to the reverse-stroke chamber is larger than that directed to the rear working chamber, the ram moves towards the nut, coming to the initi-al position.
Very o~ten, whe~ tbe tool stops inside the well, it cannot be restarted and has to be extracted outside by opening the well which is not always feasible. ~hese disad-vantages are due, mo~tly, to imperf~ction of the air distri-buting mechanisms which are highly sensitive to impact loads, deformations of the body and jamming of the ram in the body.
Enown in the prior art are per¢ussion tools comprising a hollow cylindrical body with a ram inside, a stepped slide valve, a ~lange, a tubular shock absorber and a nut. In these tools the ram having axial and radial channels in the tail portion rests on the inner walls of the body by two projections (with a provision for reciprocation) and its front portion forms, together with the walls of the body, a chamber which is supplied through said channels with compressed air which reciprocates the ram. ~he slide val~e has the form of a double-step bushing located in the tail portion of the body so that its large-diameter step is loca-téd in the axial channel of the ram a~d puts the source of compressed air in communication with radial channels which are periodically covered by said slide valve in the course of ram movement.
The small-diameter step of the bushing is connected by a tubular shock absorber ~ith a flange ~hich is ri~idly fixed to the tail portion of the body by a nut and has holes for the discharge o~ the exhausted air This la~out of the air distributing mechanism is complicated Besides, t~e provision of a slide valve often leads to jamming of the ram on it whereas the tubular shock absorber in the percussion tools is neither reliable nor durable which frequently results in breaking o~ the slide ~alve.
Also known i~ the prior art is a pneumatic percussion tool comprising a hollow cylindrical body whose open end is closed by a nut. The nut has channels which open at one end on its internal cglindrical sur~ace. Reciprocating inside the body is a stepped ram whose front portion forms, together with the body walls, a reverse-s~roke chamber.
~he ram is provided with an axial channel and a radial channel communicatiDg with the axial one and servi~g for the supply of compressed air from the line into the reverse-stroke chamber, said air moving the ram. ~he surface of the large-diameter step is pxovided with longitudinal channels for the discharge of compressed air from the rever-se-stroke chamber. The body has a recess in the front por-tion, and a discharge hole.
~ he internal surface of the nut and the stepped ram 10~4046 form the rear working chamber. The internal surface of the body, the face of the nut and the face of the large-diameter step of the ram form an annular space communicating with the atmosphere.
A disadvantage of the prior art design consists in that it has restricted possibilities with respect to increasing the impact power of the tool because the surface area of the ram on the forward stroke is utilized but partly.
An ob~ect of the present invention is to eliminate the aforesaid disadvantages of the pneumatic percussion tools.
Another object of the invention is to provide a pneumatic percussion tool of a higher power capacity and efficiency.
Still another object of the invention is to provide a pneumatic percussion tool incorporating a reliable system of air distribution.
A further object of the invention is to improve the strength of the tool body.
And one more object of the invention is to improve the reliability of the tool in service.
According to the present invention there is provided a pneumatic percussion tool comprising: a hollow cylindrical body closed at one end which is adapted to be driven into the ground and open at the other end; a nut closing the other end of said body and having defined therein an axial bore for connection to a compressed air line; a stepped ram accommodated in said body and arranged to reciprocate therein between a forward position and a rear position, said ram having a front portion and a rear reduced-diameter portion, said rear portion extending into said bore; a reverse-stroke chamber between the closed end of said cylindrical body and a front end of said ram; an axial channel in said ram extending from a rear end `` 1094046 thereof to a point within said front portion and a radial channel in said front portion extending to a peripheral surface thereof and communicating with said axial channel, an inner surface of said body being stepped such that said radial bore is closed off by said inner surface except when said ram is in the forward position, a rear working chamber defined in said bore to the rear of said reduced-diameter portion of the ram, said rear working chamber communicating with said reverse-stroke chamber through said axial channel and said radial channel when said ram is in the forward position; a longitudinal channel formed on the peripheral surface of the front portion of said ram, communicating with the reverse-stroke chamber and terminating at a point forward of the rear of the front portion; vent means for communicating said longitudinal channel to the atmosphere when said ram is in the rear position whereby, in said rear position, air in said reverse-stroke working chamber is vented to the atmosphere through said longitudinal channel; an annular space defined in said cylindrical body between the front portion of said ram and said nut, said annular space being vented to the atmosphere when said ram is in the forward position; a longitud-inal channel in said nut communicating with said annular space and a first port opening into said axial bore; a second port in said rear portion of the stepped ram and communicating with the axial channel thereof; said first and second ports located so as to be in alignment in the rear position of said ram whereby, in said rear position, compressed air from said rear working chamber enters said annular space through the longitud-inal channel in said nut and, together with compressed air in said axial channel in said ram, drives said ram forwards, and said second port being closed off by said bore when the ram is in the forward position, said ram being driven rearwards when in the forward position by air entering the reverse-stroke chamber through said axial and radial channels and acting on the front end of said ram.
Such a design raises the impact power of the tool because the entire cross-section area of the ram is subjected to the pressure of compressed air.
To improve operational reliability it is expedient that the large-diameter step of the ram, closer to its small-diameter step, should have a circular recess receiving the open ends of the longitudinal channels of the large-diameter step for communicating the reverse-stroke chamber with the atmosphere.
-6a-... .
iO~4046 It is also advisable that the ram should have an addi-tional channel which should open at one end on the cylindrical surface of the large diameter step whereas its other end should open on the cylindrical surface of the small-diameter step of the ram and the small-diameter step should be provided with ports opening into said additional channel.
This ensures the discharge of the used air through the nut and thus dispenses with the side holes in the body which improves the strength of the latter. Besides, in this manner there is noneed in the protective housing which is installed on the body to keep dirt out of the tool space.
Simplicity of the design is achieved by forming the additional channels with the aid of a recess on the small-diameter step of the ram and by a cylindrical sleeve installed rigidly over said recess on the small-diameter step, said cylindrical sleeve having air admission and discharge holes.
Now the invention will be made more apparent by way of examples of its realization with reference to the accompany-ing drawings in which:
Fig. 1 is a longitudinal section of the pneumatic per-cussion tool according to the invention;
Fig. 2 is a section taken along line II-II in Fig. l;
Fig. 3 shows a version of the tail portion of the pneumatic percussion tool in which the circular recess is made on the small-diameter step of the ram at the point of the radial port, with a partial cut-out;
~0~?4046 ~ ig. 4 shows a version Or the pneumatic percusston tool r~erein the ram i~ provided with an additional channel ~or discharging the compressed air through the end portion of the a longitudinal section;
~ i~. 5 ~hows a version of the pneumatic percussion tool wherein the additional channel i9 formed by a recess on the small-diameter ~tep and by a cylindrical sleeve installed rigidly over said recess on the small-diameter step of the ram, a longitudinal section;
~ig. 6 i8 a section taken along line VI - ~I in ~ig. 5;
~ig. 7 is a section taken along line ~ II in ~ig. 5.
The pneumatic percussion tool according to the invention comprises a hollow cylindrical body 1 (Fig. 1) accomodating a ~tepped ram 2, and a nut 3 which covers the open end of the body 1 and ~erves for connecting a compre~sed air line 4. Said line 4 i8 connected to a source of compresRed air (not ~hown in the drawing) of any conventional type, e.g. a compres~or.
The ram 2 consists of two interconnected cylindrical lO9A046 steps, the front step being larger in diameter. The front portion of the large-diameter step o~ the ram 2 and the ~alls of the bod~ 1 form a rever~e-stroke chamber 5. The cylindrical sur~ace of the small-diameter step of the step-ped ram 2, the face of the nut 3 and the face of the large--diameter step of the ram 2 form an annular space 6. The faces of the small-diameter step and of the nut 3 form a rear working chamber 7 which is in constant communication with the compressed air line 4.
~ he side walls of the bod~ 1 have discharge hole s 8 located at such a distance from the ~ront end of the body 1 as to ensure the discharge of compressed air from the reverse-stroke chamber 5 when the ram 2 is in the rearmost position as shown in Fig. 1.
~ he stepped ram 2 has an axial chan~el 9 and a radial channel 10 communicating with the axial channel, both boing intended to deli~er compressed air into the reverse-stroke chamber 5 from the rear ~orkiDg chamber 7. ~he radial channel 10 opens on the cylindrical surface of the large-diameter step. The small-diameter step is provided with a radial port 11.
The nut 3 has longitudinal channels 12 (Figs 1, 2) ope-ning on the internal face surface of the nut 3 (Fig. 1) at one end and on its cylindrical surface interacting with the ram 2 at the other. The nut 3 has a recess 13 receiving its admission channel 12.
109~046 The recess 13' can also be made on the stepped ram 2 (~ig. 3) in which case the radial port 11' opens into said recess. The surface of the large-diameter step oi the ram
~ he invention will be used to the best advantage for driving wells through compacted ground.
It can also be useful for dri~i~g pipes, èarthing electrodes, wooden and metallic slutted piles into the ground.
Enown in the prior art are pneumatic percussion tools, for example for holi~g wells in the ground consisting of a hollo~ cylindrical body accom~odating a stepped ram provi-ded with a space in the tail portion, and a port. ~here also is a nut which covers the space of the body and mounts an air-distributing meehanism. ~he air-distributing mechanism is made in the form of a stepped branch pipe rigidly fixed by the tail portion to the nut. The front bigger step of the branch pipe is mounted inside the ram.
When the compresse~ air supply is turned on, ,the step-ped ram starts reciprocating and, being in the forward position strikes the body thus driving the tool into the ground. ~he compressed air is constantly fed into the rear working chamber formed by the walls of the ram and branch pipe. When the ram occupies the forward position the compressed air flows through the port in the ram into the reverse-stroke cham~er a~d, owin~ to the fact that the Qur~ace area of the ram dire¢ted to the reverse-stroke chamber is larger than that directed to the rear working chamber, the ram moves towards the nut, coming to the initi-al position.
Very o~ten, whe~ tbe tool stops inside the well, it cannot be restarted and has to be extracted outside by opening the well which is not always feasible. ~hese disad-vantages are due, mo~tly, to imperf~ction of the air distri-buting mechanisms which are highly sensitive to impact loads, deformations of the body and jamming of the ram in the body.
Enown in the prior art are per¢ussion tools comprising a hollow cylindrical body with a ram inside, a stepped slide valve, a ~lange, a tubular shock absorber and a nut. In these tools the ram having axial and radial channels in the tail portion rests on the inner walls of the body by two projections (with a provision for reciprocation) and its front portion forms, together with the walls of the body, a chamber which is supplied through said channels with compressed air which reciprocates the ram. ~he slide val~e has the form of a double-step bushing located in the tail portion of the body so that its large-diameter step is loca-téd in the axial channel of the ram a~d puts the source of compressed air in communication with radial channels which are periodically covered by said slide valve in the course of ram movement.
The small-diameter step of the bushing is connected by a tubular shock absorber ~ith a flange ~hich is ri~idly fixed to the tail portion of the body by a nut and has holes for the discharge o~ the exhausted air This la~out of the air distributing mechanism is complicated Besides, t~e provision of a slide valve often leads to jamming of the ram on it whereas the tubular shock absorber in the percussion tools is neither reliable nor durable which frequently results in breaking o~ the slide ~alve.
Also known i~ the prior art is a pneumatic percussion tool comprising a hollow cylindrical body whose open end is closed by a nut. The nut has channels which open at one end on its internal cglindrical sur~ace. Reciprocating inside the body is a stepped ram whose front portion forms, together with the body walls, a reverse-s~roke chamber.
~he ram is provided with an axial channel and a radial channel communicatiDg with the axial one and servi~g for the supply of compressed air from the line into the reverse-stroke chamber, said air moving the ram. ~he surface of the large-diameter step is pxovided with longitudinal channels for the discharge of compressed air from the rever-se-stroke chamber. The body has a recess in the front por-tion, and a discharge hole.
~ he internal surface of the nut and the stepped ram 10~4046 form the rear working chamber. The internal surface of the body, the face of the nut and the face of the large-diameter step of the ram form an annular space communicating with the atmosphere.
A disadvantage of the prior art design consists in that it has restricted possibilities with respect to increasing the impact power of the tool because the surface area of the ram on the forward stroke is utilized but partly.
An ob~ect of the present invention is to eliminate the aforesaid disadvantages of the pneumatic percussion tools.
Another object of the invention is to provide a pneumatic percussion tool of a higher power capacity and efficiency.
Still another object of the invention is to provide a pneumatic percussion tool incorporating a reliable system of air distribution.
A further object of the invention is to improve the strength of the tool body.
And one more object of the invention is to improve the reliability of the tool in service.
According to the present invention there is provided a pneumatic percussion tool comprising: a hollow cylindrical body closed at one end which is adapted to be driven into the ground and open at the other end; a nut closing the other end of said body and having defined therein an axial bore for connection to a compressed air line; a stepped ram accommodated in said body and arranged to reciprocate therein between a forward position and a rear position, said ram having a front portion and a rear reduced-diameter portion, said rear portion extending into said bore; a reverse-stroke chamber between the closed end of said cylindrical body and a front end of said ram; an axial channel in said ram extending from a rear end `` 1094046 thereof to a point within said front portion and a radial channel in said front portion extending to a peripheral surface thereof and communicating with said axial channel, an inner surface of said body being stepped such that said radial bore is closed off by said inner surface except when said ram is in the forward position, a rear working chamber defined in said bore to the rear of said reduced-diameter portion of the ram, said rear working chamber communicating with said reverse-stroke chamber through said axial channel and said radial channel when said ram is in the forward position; a longitudinal channel formed on the peripheral surface of the front portion of said ram, communicating with the reverse-stroke chamber and terminating at a point forward of the rear of the front portion; vent means for communicating said longitudinal channel to the atmosphere when said ram is in the rear position whereby, in said rear position, air in said reverse-stroke working chamber is vented to the atmosphere through said longitudinal channel; an annular space defined in said cylindrical body between the front portion of said ram and said nut, said annular space being vented to the atmosphere when said ram is in the forward position; a longitud-inal channel in said nut communicating with said annular space and a first port opening into said axial bore; a second port in said rear portion of the stepped ram and communicating with the axial channel thereof; said first and second ports located so as to be in alignment in the rear position of said ram whereby, in said rear position, compressed air from said rear working chamber enters said annular space through the longitud-inal channel in said nut and, together with compressed air in said axial channel in said ram, drives said ram forwards, and said second port being closed off by said bore when the ram is in the forward position, said ram being driven rearwards when in the forward position by air entering the reverse-stroke chamber through said axial and radial channels and acting on the front end of said ram.
Such a design raises the impact power of the tool because the entire cross-section area of the ram is subjected to the pressure of compressed air.
To improve operational reliability it is expedient that the large-diameter step of the ram, closer to its small-diameter step, should have a circular recess receiving the open ends of the longitudinal channels of the large-diameter step for communicating the reverse-stroke chamber with the atmosphere.
-6a-... .
iO~4046 It is also advisable that the ram should have an addi-tional channel which should open at one end on the cylindrical surface of the large diameter step whereas its other end should open on the cylindrical surface of the small-diameter step of the ram and the small-diameter step should be provided with ports opening into said additional channel.
This ensures the discharge of the used air through the nut and thus dispenses with the side holes in the body which improves the strength of the latter. Besides, in this manner there is noneed in the protective housing which is installed on the body to keep dirt out of the tool space.
Simplicity of the design is achieved by forming the additional channels with the aid of a recess on the small-diameter step of the ram and by a cylindrical sleeve installed rigidly over said recess on the small-diameter step, said cylindrical sleeve having air admission and discharge holes.
Now the invention will be made more apparent by way of examples of its realization with reference to the accompany-ing drawings in which:
Fig. 1 is a longitudinal section of the pneumatic per-cussion tool according to the invention;
Fig. 2 is a section taken along line II-II in Fig. l;
Fig. 3 shows a version of the tail portion of the pneumatic percussion tool in which the circular recess is made on the small-diameter step of the ram at the point of the radial port, with a partial cut-out;
~0~?4046 ~ ig. 4 shows a version Or the pneumatic percusston tool r~erein the ram i~ provided with an additional channel ~or discharging the compressed air through the end portion of the a longitudinal section;
~ i~. 5 ~hows a version of the pneumatic percussion tool wherein the additional channel i9 formed by a recess on the small-diameter ~tep and by a cylindrical sleeve installed rigidly over said recess on the small-diameter step of the ram, a longitudinal section;
~ig. 6 i8 a section taken along line VI - ~I in ~ig. 5;
~ig. 7 is a section taken along line ~ II in ~ig. 5.
The pneumatic percussion tool according to the invention comprises a hollow cylindrical body 1 (Fig. 1) accomodating a ~tepped ram 2, and a nut 3 which covers the open end of the body 1 and ~erves for connecting a compre~sed air line 4. Said line 4 i8 connected to a source of compresRed air (not ~hown in the drawing) of any conventional type, e.g. a compres~or.
The ram 2 consists of two interconnected cylindrical lO9A046 steps, the front step being larger in diameter. The front portion of the large-diameter step o~ the ram 2 and the ~alls of the bod~ 1 form a rever~e-stroke chamber 5. The cylindrical sur~ace of the small-diameter step of the step-ped ram 2, the face of the nut 3 and the face of the large--diameter step of the ram 2 form an annular space 6. The faces of the small-diameter step and of the nut 3 form a rear working chamber 7 which is in constant communication with the compressed air line 4.
~ he side walls of the bod~ 1 have discharge hole s 8 located at such a distance from the ~ront end of the body 1 as to ensure the discharge of compressed air from the reverse-stroke chamber 5 when the ram 2 is in the rearmost position as shown in Fig. 1.
~ he stepped ram 2 has an axial chan~el 9 and a radial channel 10 communicating with the axial channel, both boing intended to deli~er compressed air into the reverse-stroke chamber 5 from the rear ~orkiDg chamber 7. ~he radial channel 10 opens on the cylindrical surface of the large-diameter step. The small-diameter step is provided with a radial port 11.
The nut 3 has longitudinal channels 12 (Figs 1, 2) ope-ning on the internal face surface of the nut 3 (Fig. 1) at one end and on its cylindrical surface interacting with the ram 2 at the other. The nut 3 has a recess 13 receiving its admission channel 12.
109~046 The recess 13' can also be made on the stepped ram 2 (~ig. 3) in which case the radial port 11' opens into said recess. The surface of the large-diameter step oi the ram
2 (~ig. 1) is provided wit~ longitudinal channels 14 ~hich open at one end into the reverse-stroke chamber 5, and with a circular recess 15 located closer to the small-diameter step of the ram 2 and receiving the other ends of the longi-tudinal channels 14. ~he body 1 has a recess 16 located i~
the front portion of the body 1~ To ensure the discharge of compressed air through the end portion of the tool and to impro~e the strength of the body 1" (Fig. 4), the stepped ram 2" is provided with an additional channel 17 one end of which opens on the cylindrical surface of the large-diam-eter step whilst its other end opens on the cylindrical surface of the small-diameter step of the ram 2". Fig. 4 shows the additional channel 17 made by drilling. At the side of the rear cham~er 7" the additional channel 17 is closed with a pl~g 18. The small-diameter step o~ the step-ped ram 2" is provided with ports 19 and 20 opening into said additional channel 17. The body 1" has a recess 21 loca-ted-in its middle portion, approximately. The nut 3" has a discharge channel 22 for discharge of the compressed air, one end of said cha~nel opening on the external face surface of the nut 3" whilst its other end opens on its _10 -10!~4046 cylindrical surface interacting with the small-diameter step o~ the ram 2".
To simplify the design of the tool and reduce the for-ces of friction between the cylindrical surface of the small-diameter step of the stepped ram 2"' (Fig. 5) and the nut 3"', the additional channel 17"' of the stepped ram 2"' can be formed by the recess 23 on the small-diameter step and by a cylindrical sleeve ~ rigidly ~ixed over said recess 23 on the small-diameter step of the ram 2"', said sleeve having a hole 25 (~ig. 5,6) coinciding with the port 11"' of the stepped ram 2"' for admitting compressed air into the annular space 6"', and discharge holes 26 (~ig. 5,7) a~d 27 (~ig. 5) opening into the additional channRl 17"' of the stepped ram 2"' for discharge the compressed air out of the reverse-stroke chamber 5"' and annular space 6"'.
~ he percussion tool accordi~g to the invention functionc as ~ollows.
As compressed air is supplied ~rom the line 4 (Fig. 1) into the rear working chamber 7, it flows through the axi-al cha~nel 9 and the radial channel 10 of the stepped ram 2 into the reverse-stroke chamber 5. Owing to the differe~ce of areas o~ the ~ace sur~aces o~ the ram 2 directed to the rear working chamber 7 and reverse stroke chamber 5, said ram starts moving towards the nut 3. During its movement the radial channel 10 is covered by the internal sur~ace o~
the body 1 so that the further movement of the ram 2 will be effected due to expansion of compressed air in the re~er-se-stroke chamber 5. At the end of the stro~e of the stepped ram 2, its circular recess 15 gets aligned with the hole 8 in the side walls of the body 1 and puts the reverse-stroke chamber 5 in communication ~ith the hole 8 of the body 1 through the longitudinal channel 14 on the large-diameter step o~ the ram 2. ~he compre8sed air escapes into the atmosp here from the reverse stroke chamber 5 through the longitudi-nal channel 14 of the ram 2 and the hole 8 in the body 1.
At the end of the stroke of the ram 2 the radial port 11 on the small-diameter step of the ram 2 gets in line with the recess 13 of the nut 3. Compressed air flows from the axial channel 9 of the ram 2 through the radial port 11, the recess 13 of the nut 3 and the longitudinal chan-nels 12 of the same nut into the annular space 6 and acts on the entire face surface of the ram 2. Being pressed by the compressed air contained in the rear working chamber 7 and in the annular space 6, the stepped ram 2 stops and starts moving forward. At a preset distance from the beginning of motio~ of the stepped ram 2 its radial port 11 on the small diameter step is covered by the internal surface of the nut
the front portion of the body 1~ To ensure the discharge of compressed air through the end portion of the tool and to impro~e the strength of the body 1" (Fig. 4), the stepped ram 2" is provided with an additional channel 17 one end of which opens on the cylindrical surface of the large-diam-eter step whilst its other end opens on the cylindrical surface of the small-diameter step of the ram 2". Fig. 4 shows the additional channel 17 made by drilling. At the side of the rear cham~er 7" the additional channel 17 is closed with a pl~g 18. The small-diameter step o~ the step-ped ram 2" is provided with ports 19 and 20 opening into said additional channel 17. The body 1" has a recess 21 loca-ted-in its middle portion, approximately. The nut 3" has a discharge channel 22 for discharge of the compressed air, one end of said cha~nel opening on the external face surface of the nut 3" whilst its other end opens on its _10 -10!~4046 cylindrical surface interacting with the small-diameter step o~ the ram 2".
To simplify the design of the tool and reduce the for-ces of friction between the cylindrical surface of the small-diameter step of the stepped ram 2"' (Fig. 5) and the nut 3"', the additional channel 17"' of the stepped ram 2"' can be formed by the recess 23 on the small-diameter step and by a cylindrical sleeve ~ rigidly ~ixed over said recess 23 on the small-diameter step of the ram 2"', said sleeve having a hole 25 (~ig. 5,6) coinciding with the port 11"' of the stepped ram 2"' for admitting compressed air into the annular space 6"', and discharge holes 26 (~ig. 5,7) a~d 27 (~ig. 5) opening into the additional channRl 17"' of the stepped ram 2"' for discharge the compressed air out of the reverse-stroke chamber 5"' and annular space 6"'.
~ he percussion tool accordi~g to the invention functionc as ~ollows.
As compressed air is supplied ~rom the line 4 (Fig. 1) into the rear working chamber 7, it flows through the axi-al cha~nel 9 and the radial channel 10 of the stepped ram 2 into the reverse-stroke chamber 5. Owing to the differe~ce of areas o~ the ~ace sur~aces o~ the ram 2 directed to the rear working chamber 7 and reverse stroke chamber 5, said ram starts moving towards the nut 3. During its movement the radial channel 10 is covered by the internal sur~ace o~
the body 1 so that the further movement of the ram 2 will be effected due to expansion of compressed air in the re~er-se-stroke chamber 5. At the end of the stro~e of the stepped ram 2, its circular recess 15 gets aligned with the hole 8 in the side walls of the body 1 and puts the reverse-stroke chamber 5 in communication ~ith the hole 8 of the body 1 through the longitudinal channel 14 on the large-diameter step o~ the ram 2. ~he compre8sed air escapes into the atmosp here from the reverse stroke chamber 5 through the longitudi-nal channel 14 of the ram 2 and the hole 8 in the body 1.
At the end of the stroke of the ram 2 the radial port 11 on the small-diameter step of the ram 2 gets in line with the recess 13 of the nut 3. Compressed air flows from the axial channel 9 of the ram 2 through the radial port 11, the recess 13 of the nut 3 and the longitudinal chan-nels 12 of the same nut into the annular space 6 and acts on the entire face surface of the ram 2. Being pressed by the compressed air contained in the rear working chamber 7 and in the annular space 6, the stepped ram 2 stops and starts moving forward. At a preset distance from the beginning of motio~ of the stepped ram 2 its radial port 11 on the small diameter step is covered by the internal surface of the nut
3 ~hilst the recess 13 of the nut 3 is covered by the small--diameter step of the ram 2. ~urther movement of the stepped ram 2 is effected due to the energy of the e~panding air in 1()~4046 the annular spsce 6 and the pressure of compressed air in the rear working chamber 7. At the end of the forr~ard stroke (foremost position of the ram 2 shown i~ Fig. 1) the ram 2 strikes the body 1. At the same time the ram 2 uncovers the holes 8 in the side walls of the body 1 and the used compressed air is expelled into the atmosphere ~rom the annular space 6. ~he radial channel 10 of the stepped ram 2 opens i~to the recess 16 i~ the front part o~ the body 1 thereby putti~g the reverse-stroke chamber 5 i~ communicatio~
with the rear working chamber 7. ~he compressed air flows ~rom the supply line 4 into the rear working chamber 7 and, through the axial channel 9 and the radial channel 1~ of the ram 2, enters the reverse-stroke chamber 5. ~nen the working cycle is repeated over again.
~ he circular recess 13 of the nut ~ (Fig. 1) and the circular recess 23 (~ig. 5) on the small-diameter step o~ the stepped ram 2"' as well as the circular recess 15 (~ig. 1) on the large diameter step of the stepped ram 2 are necessary in order to maintai~ uninterrupted admission of compressed air into the annular space 6 (Fig. 1) and 6"' ~Fig. 5) and discharge o~ coiiapressed air from the reverse s-troke chamber 5 (Fig. 1) and 5"' (Fig. 5) into the atmos~he-re in case the stepped ram 2 (~ig. 1) and 2"' (Fi~. 5) turns around the longitudinal axis.
10~4046 If the tool is realized as sho~n in ~ig. 4, it iunctions in a similar manner except for the fact that the compressed ~ir is discharged from the reverse-stroke chamber 5" and annular space 6" through the rear end of the tool, passing through the additional channel 17 of the stepped ram 2" and the discharge channels 22 of the nut 3".
In the position sho~nn in ~ig. 4 the compressed air ~lows through the axial channel 9" and the radial channel 1~" of the stepped ram 2" into the reverse stroke chamber 5".
In this period the annular space 6" is vented to the atmosp-here through the port 19, additional channel 17, port 20 of the stepped ram 2" and the discharge channel 22 of the ~ut 3"~
~ he compressed air acts on the face surface o~ the small-diameter step o* the stepped ram 2" directed to the rear chamber 7" and on the face sur~ace of the large-diameter step of the stepped ram 2" directed to the reverse-stroke chamber 5".
Due to the difference in the areas o~ the faces o~
the steps of the stepped ram 2" the latter begins to moYe towards the nut 3". In the course of its movement the ~ort chan~l ~a o ~
19 gets in line with the ~Y~bY~-¢3Y=F~ the nut 3" whilst the longitudinal ohannel 14" on the large-diameter step of the stepped ram 2" opens into the recess 21 of the body 1". The additional.channRl 17 of the ram 2" al80 open~
into the same recess 21. The compressed air escapes into the atmosphere from the reverse-stroke chamber 5" through the longitudinal channel 14" of the ram 2", the recess 21 of the body 1" the additional channel 17 and the port ~
of the stepped ram 2" and through the discharge channel 22 of the nut 3".
At the same moment the radial port 11" of the ra~ "
gets in line with the recess 13" o~ the nut 3" and the compressed air enters the annular space 6" from the rear working chamber 7" through the æial channel 9", the port 11" of the ram 2", the recess 13" and the admission channel 12" of the ~ut 3". Being acted upon by compressed air in the rear ~orking chamber 7" a~d annular space 6", the stepped ram 2" stops and begins to move forward to strike the body 1 " . , At t~e end of the stroke of the ram 2" its port 20 gets in line with the admission hole of the channel 22 and the compressed air escapes into the atmosphere from the ann~lar space 6" through the port 19, additional channel 17, port 20 of the ram 2" and the discharge channel 22 of the nut 3".
Compressed air enters the reverse-stroke chamber 5"
and the cycle is repeated over again.
~ his layout of the tool makes it possible to make a ~0~4046`
solid body 1" without side holes which improves its strength.
Besides, this makes it posRible to dispense with the protecti ve housing installed on the body 1" to keep dirt out o~
the spaces of the ram 2"; this promotes the reliability in ser~ice.
If the tool is realized as sho~n in ~ig. 5, it opera-tes in a similar manner as the versio~ illustrated in Fig. 4.
The compressed air is discharged into the atmosphere from the annular space 6"' (Fig. 5) through the hole 26 of the slee~e 24, the additional channel 17"' formed by the walls o~ the stepped ram 2"' and of the cylindrical sleeve 24, thro ugh the hole 27 of the cylindrical sleeve 24 and the dischar-ge ~al~e 22"' o~ the nut 3"'. The compressed air contained i~ the re~erse-stroke chamber 5"~ i9 discharged i~to the atmosphere through the longitudinal channel 14"' of the ram 2"', the recess 21"' of the body 1"', additional channel 17"', the hole 26 in -the cylindrical slee~e 24 and the dis-charge cha~nel 22"' of the nut 3"'.
~ he compressed air is admitted into the annular space 6"' from the rear chamber 7"' th~ough the axial channel 9"
the port 11"' of the ram 2"', the air admission hole 25 of the cylindrical slee~e 24, the recess 13"', a~d the admis-sion cha~nel 12"' of the nut 3"'.
Such a layout adds to simplification of the desi~n
with the rear working chamber 7. ~he compressed air flows ~rom the supply line 4 into the rear working chamber 7 and, through the axial channel 9 and the radial channel 1~ of the ram 2, enters the reverse-stroke chamber 5. ~nen the working cycle is repeated over again.
~ he circular recess 13 of the nut ~ (Fig. 1) and the circular recess 23 (~ig. 5) on the small-diameter step o~ the stepped ram 2"' as well as the circular recess 15 (~ig. 1) on the large diameter step of the stepped ram 2 are necessary in order to maintai~ uninterrupted admission of compressed air into the annular space 6 (Fig. 1) and 6"' ~Fig. 5) and discharge o~ coiiapressed air from the reverse s-troke chamber 5 (Fig. 1) and 5"' (Fig. 5) into the atmos~he-re in case the stepped ram 2 (~ig. 1) and 2"' (Fi~. 5) turns around the longitudinal axis.
10~4046 If the tool is realized as sho~n in ~ig. 4, it iunctions in a similar manner except for the fact that the compressed ~ir is discharged from the reverse-stroke chamber 5" and annular space 6" through the rear end of the tool, passing through the additional channel 17 of the stepped ram 2" and the discharge channels 22 of the nut 3".
In the position sho~nn in ~ig. 4 the compressed air ~lows through the axial channel 9" and the radial channel 1~" of the stepped ram 2" into the reverse stroke chamber 5".
In this period the annular space 6" is vented to the atmosp-here through the port 19, additional channel 17, port 20 of the stepped ram 2" and the discharge channel 22 of the ~ut 3"~
~ he compressed air acts on the face surface o~ the small-diameter step o* the stepped ram 2" directed to the rear chamber 7" and on the face sur~ace of the large-diameter step of the stepped ram 2" directed to the reverse-stroke chamber 5".
Due to the difference in the areas o~ the faces o~
the steps of the stepped ram 2" the latter begins to moYe towards the nut 3". In the course of its movement the ~ort chan~l ~a o ~
19 gets in line with the ~Y~bY~-¢3Y=F~ the nut 3" whilst the longitudinal ohannel 14" on the large-diameter step of the stepped ram 2" opens into the recess 21 of the body 1". The additional.channRl 17 of the ram 2" al80 open~
into the same recess 21. The compressed air escapes into the atmosphere from the reverse-stroke chamber 5" through the longitudinal channel 14" of the ram 2", the recess 21 of the body 1" the additional channel 17 and the port ~
of the stepped ram 2" and through the discharge channel 22 of the nut 3".
At the same moment the radial port 11" of the ra~ "
gets in line with the recess 13" o~ the nut 3" and the compressed air enters the annular space 6" from the rear working chamber 7" through the æial channel 9", the port 11" of the ram 2", the recess 13" and the admission channel 12" of the ~ut 3". Being acted upon by compressed air in the rear ~orking chamber 7" a~d annular space 6", the stepped ram 2" stops and begins to move forward to strike the body 1 " . , At t~e end of the stroke of the ram 2" its port 20 gets in line with the admission hole of the channel 22 and the compressed air escapes into the atmosphere from the ann~lar space 6" through the port 19, additional channel 17, port 20 of the ram 2" and the discharge channel 22 of the nut 3".
Compressed air enters the reverse-stroke chamber 5"
and the cycle is repeated over again.
~ his layout of the tool makes it possible to make a ~0~4046`
solid body 1" without side holes which improves its strength.
Besides, this makes it posRible to dispense with the protecti ve housing installed on the body 1" to keep dirt out o~
the spaces of the ram 2"; this promotes the reliability in ser~ice.
If the tool is realized as sho~n in ~ig. 5, it opera-tes in a similar manner as the versio~ illustrated in Fig. 4.
The compressed air is discharged into the atmosphere from the annular space 6"' (Fig. 5) through the hole 26 of the slee~e 24, the additional channel 17"' formed by the walls o~ the stepped ram 2"' and of the cylindrical sleeve 24, thro ugh the hole 27 of the cylindrical sleeve 24 and the dischar-ge ~al~e 22"' o~ the nut 3"'. The compressed air contained i~ the re~erse-stroke chamber 5"~ i9 discharged i~to the atmosphere through the longitudinal channel 14"' of the ram 2"', the recess 21"' of the body 1"', additional channel 17"', the hole 26 in -the cylindrical slee~e 24 and the dis-charge cha~nel 22"' of the nut 3"'.
~ he compressed air is admitted into the annular space 6"' from the rear chamber 7"' th~ough the axial channel 9"
the port 11"' of the ram 2"', the air admission hole 25 of the cylindrical slee~e 24, the recess 13"', a~d the admis-sion cha~nel 12"' of the nut 3"'.
Such a layout adds to simplification of the desi~n
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A pneumatic percussion tool comprising:
a hollow cylindrical body closed at one end which is adapted to be driven into the ground and open at the other end;
a nut closing the other end of said body and having defined therein an axial bore for connection to a compressed air line;
a stepped ram accommodated in said body and arranged to reciprocate therein between a forward position and a rear position, said ram having a front portion and a rear reduced-diameter portion, said rear portion extending into said bore;
a reverse-stroke chamber between the closed end of said cylindrical body and a front end of said ram;
an axial channel in said ram extending from a rear end thereof to a point within said front portion and a radial channel in said front portion extending to a peripheral surface thereof and communicating with said axial channel, an inner surface of said body being stepped such that said radial bore is closed off by said inner surface except when said ram is in the forward position;
a rear working chamber defined in said bore to the rear of said reduced diameter portion of the ram, said rear working chamber communicating with said reverse-stroke chamber through said axial channel and said radial channel when said ram is in the forward position;
a longitudinal channel formed on the peripheral surface of the front portion of said ram, communicating with the reverse-stroke chamber and terminating at a point forward of the rear of the front portion;
vent means for communicating said longitudinal channel to the atmosphere when said ram is in the rear position whereby, in said rear position, air in said reverse-stroke working chamber is vented to the atmosphere through said longitudinal channel;
an annular space defined in said cylindrical body between the front portion of said ram and said nut, said annular space being vented to the atmosphere when said ram is in the forward position;
a longitudinal channel in said nut communicating with said annular space and a first port opening into said axial bore;
a second port in said rear portion of the stepped ram and communicating with the axial channel thereof;
said first and second ports located so as to be in alignment in the rear position of said ram whereby, in said rear position, compressed air from said rear working chamber enters said annular space through the longitudinal channel in said nut and, together with compressed air in said axial channel in said ram, drives said ram forwards, and said second port being closed off by said bore when the ram is in the forward position, said ram being driven rearwards when in the forward position by air entering the reverse-stroke chamber through said axial and radial channels and acting on the front end of said ram.
a hollow cylindrical body closed at one end which is adapted to be driven into the ground and open at the other end;
a nut closing the other end of said body and having defined therein an axial bore for connection to a compressed air line;
a stepped ram accommodated in said body and arranged to reciprocate therein between a forward position and a rear position, said ram having a front portion and a rear reduced-diameter portion, said rear portion extending into said bore;
a reverse-stroke chamber between the closed end of said cylindrical body and a front end of said ram;
an axial channel in said ram extending from a rear end thereof to a point within said front portion and a radial channel in said front portion extending to a peripheral surface thereof and communicating with said axial channel, an inner surface of said body being stepped such that said radial bore is closed off by said inner surface except when said ram is in the forward position;
a rear working chamber defined in said bore to the rear of said reduced diameter portion of the ram, said rear working chamber communicating with said reverse-stroke chamber through said axial channel and said radial channel when said ram is in the forward position;
a longitudinal channel formed on the peripheral surface of the front portion of said ram, communicating with the reverse-stroke chamber and terminating at a point forward of the rear of the front portion;
vent means for communicating said longitudinal channel to the atmosphere when said ram is in the rear position whereby, in said rear position, air in said reverse-stroke working chamber is vented to the atmosphere through said longitudinal channel;
an annular space defined in said cylindrical body between the front portion of said ram and said nut, said annular space being vented to the atmosphere when said ram is in the forward position;
a longitudinal channel in said nut communicating with said annular space and a first port opening into said axial bore;
a second port in said rear portion of the stepped ram and communicating with the axial channel thereof;
said first and second ports located so as to be in alignment in the rear position of said ram whereby, in said rear position, compressed air from said rear working chamber enters said annular space through the longitudinal channel in said nut and, together with compressed air in said axial channel in said ram, drives said ram forwards, and said second port being closed off by said bore when the ram is in the forward position, said ram being driven rearwards when in the forward position by air entering the reverse-stroke chamber through said axial and radial channels and acting on the front end of said ram.
2. A pneumatic percussion tool according to claim 1, wherein a circular recess is provided on the peripheral surface of the front portion of the ram, said longitudinal channel extends into said recess, and an opening is provided in the wall of said cylindrical body such that, in the rear position of the ram, said circular recess is in alignment with said opening and the annular space is closed off from said opening by said front portion whereby air in the reverse-stroke working chamber is vented to the atmosphere, and in the forward position of the ram, said annular space is directly vented to the atmosphere by said opening.
3. A pneumatic percussion tool according to claim 1, further comprising an additional channel in said ram which communicates with a third port in the peripheral surface of said front portion, said third port being closed off by the inner surface of said body when the ram is in the forward position, and a fourth port in the rear portion of said ram, said fourth port being in alignment with a fifth port in the bore of said nut when the ram is in the forward position, said fifth port being in communication with the atmosphere, a circular recess in the wall of said cylindrical body, and said third port being arranged adjacent the point at which said longitudinal channel in the front portion terminates, said circular recess being located in said wall so that said longitudinal channel communicates with said third port via said circular recess when said ram is in the rear position, and a sixth port in said rear portion of the ram communicating said additional channel with said annular space when said ram is in the forward position, said sixth port being in alignment with said fifth port when said ram is in the rear position.
4. A pneumatic percussion tool according to claim 3, wherein the additional channel is formed by a further recess on the rear portion of the ram and a cylindrical sleeve fixed rigidly over said rear portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA304,662A CA1094046A (en) | 1978-06-02 | 1978-06-02 | Pneumatic percussion tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA304,662A CA1094046A (en) | 1978-06-02 | 1978-06-02 | Pneumatic percussion tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094046A true CA1094046A (en) | 1981-01-20 |
Family
ID=4111609
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA304,662A Expired CA1094046A (en) | 1978-06-02 | 1978-06-02 | Pneumatic percussion tool |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1094046A (en) |
-
1978
- 1978-06-02 CA CA304,662A patent/CA1094046A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |