CA1087939A - Compressed air operated setting device - Google Patents
Compressed air operated setting deviceInfo
- Publication number
- CA1087939A CA1087939A CA290,526A CA290526A CA1087939A CA 1087939 A CA1087939 A CA 1087939A CA 290526 A CA290526 A CA 290526A CA 1087939 A CA1087939 A CA 1087939A
- Authority
- CA
- Canada
- Prior art keywords
- cylinder
- compressed air
- housing
- wall
- piston
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25C—HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS
- B25C1/00—Hand-held nailing tools; Nail feeding devices
- B25C1/04—Hand-held nailing tools; Nail feeding devices operated by fluid pressure, e.g. by air pressure
- B25C1/044—Hand-held nailing tools; Nail feeding devices operated by fluid pressure, e.g. by air pressure with movable main cylinder
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Portable Nailing Machines And Staplers (AREA)
- Actuator (AREA)
- Sealing Devices (AREA)
- Package Closures (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In a compressed air operated device for driving or setting fastening elements into a receiving material, a driving piston is axially displaceable within a cylinder in the device.
Two separate supplies of compressed air are provided to the cylinder, one for driving the piston forwardly and the other for moving the piston rearwardly after the completion of the driving action. The parts of the device forming the cylinder are arranged to provide an opening between the cylinder and the exterior of the device. The opening is normally kept closed, however, it is opened when the piston is driven for inserting a fastening element, so that air in the cylinder ahead of the piston can be exhausted to assure the optimum displacing effect of the compressed air acting on the piston.
In a compressed air operated device for driving or setting fastening elements into a receiving material, a driving piston is axially displaceable within a cylinder in the device.
Two separate supplies of compressed air are provided to the cylinder, one for driving the piston forwardly and the other for moving the piston rearwardly after the completion of the driving action. The parts of the device forming the cylinder are arranged to provide an opening between the cylinder and the exterior of the device. The opening is normally kept closed, however, it is opened when the piston is driven for inserting a fastening element, so that air in the cylinder ahead of the piston can be exhausted to assure the optimum displacing effect of the compressed air acting on the piston.
Description
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The present invention is directed to ~ compre~ed air operated setting device includiny a driving piston displaCeable through a cylinder by means of compressed air supplied into the cylinder. Further, the invention concerns an arrangement of the - cylinder-permitting the discharge of air from in front of the piston as it is driven through the cylinder.
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The effectiveness of compressed air operated setting ::, devices depends particularly on the kinetic energy imparted . .
r'~.' to the driving piston. The kinetic energy is directly related , :..
to the velocity imparted to the driving piston. In other words, the greater the working stroke-speed of the driving piston, the greater is the kinetic energy of the piston.
.,-:~ Compressed air operated setting devices are known in .: ;
which the driving piston has a head on its rear end which is mounted in sealed engagement with the guide bore in the cylinder.
Further, the piston includes a shank extending forwardly from the head, that is, it extends in the driving direction of the piston.~ The shank projects outwardly from the cylinder in the driving directionc After each driving stroke is effected, the ,;,: ,, ~ 20 piston is returned to its rearward position within the cylinder -;
by a supply o~ low pressure air. The low pressure air is introduced into the cylinder from a supply source at a location forwardly of the piston head after it has completed the driving action. The driving piston is maintained in ~he rear end of the cylinder by the low pressure air. Furt~er, the supply of air at the head of the piston is maintained after its return stroke has been effected. Subsequently, on the next driving stroke air , compressed at a higher pressure is introduced into the cylinder ~;:.
~`1 rearwardly of the driving piston. This supply of higher pressure ;~ 3a air directed against the rearward end of the piston head accelerates ''`':~'`.'~
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~;` the piston ~orwarclly so th~t lt can per~orm the de~lred work.
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While the use of these various measures ha~ increased the speed of the driving pi~ ton, for carrylng out certain work, such as setting fastening elements into hard receiving materials, --,:..................................................................... .
'~','' the piston speed is still too low. The low speeds are caused ,"'~ by the air present in the front of the driving piston during its , - , working st~oke. This air is not-discharged rapidly enough from :.~
~'" the cylinder with the results that an air cushion is present ~',,, acting against the acceleration of the piston.
' This disadvantage in prior art devices resides in the . . .: . .
~;``,~ fact that the dlscharge flow of air from the cylinder passes ~-' through the supply'channel for low pressure, return air in the forward end of the cylinder. The supply channel provides the air ~ ~, . . .
i;"' for displacing the driving piston to the rear end of the cylinder.
,'~',' The operation of the supply channel is regu;lated by a special ~ ".,~ .
~'~, control including mechanical valves. Such an arrangement for discharging the air is unsatisfactory, because of the amount . . i~.: . -`',~',~, of air ~o be exhausted and the reaction time of the valves.
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~-' Morsover, such mechanical valves are very cumbersome,and expensive .~ ., ~ .
~, 20 and have a tendency to malfunction or operate improperly, Ther,efore, the primary object of the present invention ~,"` is to provide a compressed air operated setting device in which the air ahead of the piston during its working stroke is discharged in an accelerated manner without involving the use of any complex mechanisms which have a tendency to malfunction.
In accordance with the present invention, this object ~, is achieved by constructing a portion of the cylinder in the :;~ device for axial movement relative to the housing of the device ,i,` so that such movement effects the opening of outlets for exhausting the gaseous medium during the working stroke of the piston.
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The portion of -the cylinder through which the ga~eous medium is supplied ~or moving the piston forwardly~ i5 forme~ as ".,. ~
a tubular shaped member closed at the rear by an end wall forming a closure for the rearward end of the cylinder bore. The means . .
for introducing the compress~d air into the cylinder for driving the piston is connected to the end wall.
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If compressed air is introduced into the cylinder behind the piston with the piston located in its rearward position in the cylinder, the piston is accelerated forwardly and, at the same time, the rear end wall of the cylinder through which the air is ~. i charged is displaced rearwardly relative to the housing. As the portion of the cyIinder moves in the rearward direction, one or a number of discharge outlets open through the cylinder and the housing adjacent the forward end of the cylinder. The air or other gaseous medium within the cylinder ahead of the piston is dis-charged to the exterior of the setting device, that is, to the ambient atmosphere.
. ., With this arrangement, it is necessary for the channel which supplies the gaseous medium for moving the piston rearwardly, ~' 20 to exhaust the medium in front of the piston during its working ~;
; stroke. Further, the one-way function of the valves in the ~` control circuit associated with the supply channel afford a ~; trouble-free and simple construction of these elements. The size of the discharge openings for the setting device can be ~` selected as any suitable size. Further, their arrangement and `i, configuration can be varied in accordance with the conditions ' experienced. For-example, the outlet openings can be provided ~ .
~; in the cylinder and in the housing which encloses the cylinder ~` so that the openings in the non-operatingcondition of the device are closed. When the movable portion of the cylinder is displaced . . - .
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the outlets are opened. In a particularly effective arrangement `~ of the present invention, the discharge outlet is located adjacent to the end of the cylinder through which the medium is supplied -~; for moving the drivlng piston rearwardly. Furthermore, the j : width of the gap or slot providing the discharge outlet may . ~ .
adapt itself to the working pressure so that the outlet opening ` becomes automatically larger with increasing working pressure , ...
^ due to increased displacement of ~he movable cylinder part.
To maintain the discharge outlets closed under ordinary .: .
t 10 conditions, a biasing means can be used which maintains the movable portion of the cylinder in a forward position. Such ~s biasing means assures that the movable cylinder part is returned ; to the closing position after the completion of the driving : i';
operation, The force exerted by the biasing means should be greater than the force asserted in returning the piston to its rearward position within the cylinder so that the movable cylinder part can be returned to the closing position.
Advantageously, the biasing means can be a compression i. r.. : ., ~
spring such as a helical spring. The particular advantage of a compression spring resides in the fact that it is subject to a much lower degree of overtension as compared to other types of springs, such as a spring subject to drawing forces. ~lowever, as ~ a general principle it is also possible to use a compressed air :''t`"' or gas cushion as the biasing means in place of a compression spring.
` Another feature of the present invention is that the movable-part of the cylinder is pressed against a bearing surface :';,~li.................................................................. ~
on a housing for alosing the discharge outlets with the pressing ~' action being effected by the biasing means so that a sealing action is effected. In addition, the movable portion of the cylinder .. . ....
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3g also includes the connection ~or supplyiny ~he compre~sed air or effecting the working stroke of -the piston. Accordingly, when the movable par-t of the cylinder i~ displaced rearwardly an annular gap is provided between the forward end of the cylinder part and the housing affording a connection between the interior of the cylinder and the discharge openings through the housing.
The sealing action provided between the housing and the movable cylinder part facilitates the buildup of the pressure in the cylinder head of the piston for effecting its return stroke.
lQ To provide a particularly effective sealing action, it is preferable if at least one of the contacting surfaces affording the seal includes a sealing element. An O-ring member formed of oil-resistant rubber is particularly suitable for use as a sealing element.
Where high working pressures are used in the setting . ~ . . .
device, it is advantageous to limit the movement of the movable cylinder part toward the r~ar end of the housing. By limiting ,,,.~:, `the mou~ment, a complete compression of the biasing means is ~ prevented. Accordingly, the housing provides an abutment or ~ 20 stop surface which limits the rearward movement of the movable cylinder part. Such an abutment or stop can be constructed in ;i~ I
i~ the form of an annular or ring-shaped shoulder. Further, stop ;~
pins or other abutment members can be used in limiting the ~ movements of the cylinder part. Still another feature of the .~ invention is the provision of a sealing lip about an opening `~ through an end wall of the cylinder through which compressed air ; is supplied for driving the piston. This sealing lip cooperates with the driving piston when the piston is in its rearward `; position.
This arrangement of the opening which supplies the ~ .;
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working compressed air into the cylinder aEfords a very ~imple valve arrangement.
, `~ During operation, the sealing effect between the annular ; sealing lip and the rearward facing end of the drive piston is maintained until the working pressure supplied through the rear end-of the cylinder reaches a higher force on the drive piston than the force which effected the displacement of the piston to ,; !.
-' the rearward end of the cylinder. Subsequently, with increasing .....
~; pressure of the compressed air, the drive piston starts to accelerate in the forward direction. The acceleration is considerably facilitated by the discharge of the medium located within the cylinder and forwardly of the piston head. The ~ c,:l `~ medium flows through the discharge outlets opening through the ,`~ cylinder and the housing to the ambient atmosphere. The t~
compressed air for driving the piston can be supplied directly from a compressor or from an intermediate storage vessel.
It is advantageous if the rearwardly facing end of the ~: ; piston head has a outside diameter which is larger than the outside . .
diameter of the sealing lip. Since the sealing lip, relative t 20 to the juxtaposed base of the piston head, encloses only a small circular surface on the head, the pressure of the working compressed air supplied into the cylinder at its rearward end for the driving stroke must be many times greater than the low pressure air maintaining the piston head in its rearward position in the cylinder. By overcoming this differential, the high pressure air can displace the drive piston from the sealing lip.
As soon as the sealing effect is overcome, however, the high pressure compressed air flows instantaneously over the entire cross section of the bore within the cylinder and acts, on one hand, over the entire rear end face of the piston head and, on .
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` th~ o-ther hand, on tiie ~xta~osed transverse end ~ace of the - cylinder t.Arough whlch the working compressed dir is supplied.
~ As ~ result, there is an instant or sudden acceleration of the .
drive piston ln the forward direction and a rearward movement of : the movable cylinder part relative to the housing. Due to the - rearward-movement of the cylinder part, the dis~harge outlets are opened and the drive piston can move forwardly through the ~ :, ,. . ~
cylinder without interference.
;~ Concerning the wear of the drive piston and the cylinder parts, i~ has been noted that it is advantageous to form the movable cylinder part through which the compressed air is supplied ; into the cylinder, in the form of a tubular-shaped member which ~,~ laterally encloses a guide tube or sleeve-like member forming the axially extending wall of the cylinder. The tubular-shaped ~-movable cylinder part is axially displaceable relative to the sleeve-like member portion of the cylinder. At its forward end, .~;:; .
~ the sleeve-like member is connected to the housing while its ~,i rear e~d is closed by a transverse end wall formed on the tubular-shaped member of the movable cylinder part. At its forward end, the sleeve-like member has one or several recesses or perforations permitting the medium within the cylinder at the head of the piston to escape through discharge openings formed ir. the housing when the tubular-shaped member is displaced rearwardly. A sealing member can be provided between the sleeve-like member and the movable tubular shaped member to prevent any possible outflow of the compressed air supplied into the cylinder either ahead of or behind the-drlving piston head.
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;~; In setting devices of the type described above, it is ~ advantageous if the drive piston, just prior to completing the '` 30 driving procedurer is "caught" or slowed down as it approaches ~,..: ;.~
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..,~;, ~-^ -th~ forward end of the cylinder. Accordingly, an extension of the bore within the cylinder is provided by the housing. With ~,:
such an arrangement, lt is possible to exhaust any gaseous '~x, . -;
medium ahead of the drive piston and thus provide it with a ~laximum acceleration while providing a braking action for the piston as ~, .
it reaches the forward end of the cylinder and travels beyond ~; the discharge outlets for the medium. The medium trapped in the ~i- forward extension of the cylinder provides an air cushion. Advan-"V! ' :' ~"` tageously, the housing for the setting device includes a passageway for supplying the medium into the cylinder which effects the rearward displacement of the drive piston. This supply passageway r,~"
is located so that it assures a flow of compressed air in front of the forward end face of the head even when it is in its forward position within the cylinder. As a result, after each driving movement of the piston, it will be reliably displaced ~ p"~.
to the rearward end of the cylinder~
- The various features of novelty which characterize ~ the in~ention are pointed out with particularity in the claims ;~ annexed to and forming a part of this disclosure~ For a ~. i i 20 better understanding of the invention, its operating advantages ,j~ and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the ~, invention.
i.~,: ;,, ~; IN THE DRAWINGS:-Figure 1 is an axially ex-tending sectional view through ).,.,,.,;.,,.i a compressed air operating setting device embodying the present ,~.
~ invention with the drive piston located in its rearward position;
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'~"!"~ Figure 2 is a view similar to Figure 1 but with the setting device in the working position for inserting a fastening ~'."' ~,''~' .
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element into receiving materials;
,: .,;, ,- Figure 3 is an axially extending sectional view of , ,~ r, .
~`` another embodiment of the setting device with the drive piston .
located in its rearward position, and, Figure 4 is a view similar to Figure 3 but with the ~- drive piston displaced forwardly toward its forward end position.
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In Figures 1 and 2 a compressed air operated setting device is illustrated including an axially extending cylinder 1.
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~ Part of the structure forming the cylinder 1 is axially movable -;.. , :
relative to the housing 2 of the setting device. For assembly . - - . .:
~ I purposes, the housing consists of two parts, the front housing .. ~ . .
portion 8 and the rear housing part 18. The cylinder 1 which combines with the front housing part 8 in forming the overall ., .
' cylinder through which the driving piston 4 is displaceable, ; ~ consists of an axially extending tubular shaped part 6a and a . .,. I; ~ .
- transversely extending end wall 26 closing off the rearward end :.
i of the tubular-shaped part 6~ The cylinder 1 is pressed by a ~ biasi~ member or spring 3 orwardly within the housing 2. As i viewed in Figuxes 1 and 2, the driving or working direction of ~i,;. ~ . .
~;l 20 the piston 4 is to the left, that is, the direction in which the fastening element 5 is driven out of the housing. As can be seen in Figures 1 and 2, the driving piston is movably displaceable through the cylinder and the bore 14 in the forward part 8 of the housing ~or driving a fastening element 5 into a receiving material 36, note Figure 2. During the driving action the fast-ening element 5 is guided within the bore 14 through the forward ~iii part 8 of the housing.
m The bore 6 formed within the cylinder is open at its orward end and extends into the corresponding recess 7 in the `'~ 30 rearward end of the forward housing part 8. Due to the biasing ;~
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793g i action of the compression spring 3, khe ~ront end 9 of the cylinder .~: 1 is held against the juxtaposed rear end surface 11 of the forward housing part 8. sore 6, in combination with the recess 7 which has the same diameter thus provides th~ bore through which the .~ piston head is displaceable. The juxtaposed surface 11 of the .
~-- front housing part 8 relative to the front end 9 of the cylinder ~'. forms a counter-bearing. To provide an increased sealing effect, .~ the surface or counter-bearing 11 includes a sealing element 12 in the form of an elastic O-ring.
The driving piston 4 includes a shank 13 extending ,.,~.;, -axially forwardly from its head 16. The shank is movably .i: supported within the bore 14 in the forward housing part 8 and .~ forms a seal between the cylinder bore 6 and the outlet bore 14.
. ~ Sealing ring 15 is provided at the rearward end of the bore 14 `~ in sealing engagement with the peripheral surface of the shank 13.
,` While the shank 13 is guided within the bore 14, the head 16 of -~;., the pi~ton 4 is held in sliding engagement within the guide bore .6 in t~e cylinder. Sealing element 17 is provided around the circumferential periphery of the head 16 affording a sealing ac-tion with the wall surface of the cylinder forming the bore 6.
The rearward housing part 18 is screwed onto the rear-ward end of the front housing part 8 by means of a threaded connection 19. The rear housing part 18 includes a generally .;. ~
;i cylindrical tubular-shaped portion or member laterally surrounding and spaced outwardly from the cylinder 1 with a transversely extending end wall 34. A shoulder 21 on the forward end of the . - cylinder 1, and a compressed air supply passage tu~e 22 extending rearwardly from the rear end 26 of the cylinder 1, provides ` mounting means or support for the cylinder 1 within the housing part 18. Further, the housing part 18 encloses the compression ., , . i ~'i`; .
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~. spring 3 with ~le rearward end oE the spring bearing against the inside face of -the rear housing part 18 while the front end of ~ the spring bears against the shoulder 21 on the cylinder 1.
.. Extending transversely through the rearward end of .:: - housing part 8 and the forward end of housing part 18 is a :
. - passageway 23 which opens into the recess 7, closing the forward :
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.end of the bore 6. The outer end of the passageway 23 is connected to a supply conduit 24 which extends through a handle 25. Though not shown for purposes of simplicity, a control circuit is con- -~a 10 nected to the setting device shown on Figure 1. By means of ;;~ the control circuit, a supply of low pressure compressed air ~ can be introduced through the conduit 24 into the passageway 23: ~., ~ , '. and then into the recess 7 at the forward end of the bore 6 where . ,,,~. .
it enters ahead or in front of the forwardly directed face of the .: head 16 of the drive piston 4. With this low pressure compressed air introduced into the front end of the cylinder 1, the drive ~ piston 4 can be displaced rearwardly, after having effected a driving~stroke, into the xearward position shown in Figure 1 `~'.i When the driving piston is returned rearwardly ~hrough,,~, .. j .
~:. 20 the cylinder 1 with its head contacting the rear end wall of the .. ; cylinder, it is ready for the next driving stroke and the supply ;! .
~ of low pressure compressed air is maintained to hold the piston .
`'!'~'':'' in place. Extending concentrically about the opening of tube 22 :~
` through the rear end 26 of the cylinder 1 is an annular sealing lip 27 which projects forwardly from the rear end wall 26 of the . cylinder. The cross sectional surface of the rearward face of the-head 16 encircled by the sealing lip 27 is many times smaller than the total cross section of the rearward face of head 16.
To improve the sealing action between the head 16 and the sealing lip 27, a sealing disc 28 is recessed into the . .: - , ., ;.~
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rearward fac~ o~ the ~l~ad, SealLng di~C 28 lg m~d~ of an elastic or a resilient material usually employe~ for such purposes. To assure that the pressure acting against the ~orward face of the head does not break the seal between the forward end of the ~, cylinder l and the surface-or counterbearing 11, the force exerted ii by the-compression spring 3 should be greater than the force displacing the head 16 to the rearward end of the cylinder.
The tubular connection 22 fixed to the rear end wall 26 of the cylinder forms a passageway 29 which opens through the -center of the annular sealing lip 27 into the cylinder 1. At its rear end the tubular connection 22 is joined to a compressed air line 31 for supplying the working medium into the passageway ~- 29. When the working medium is permitted to flow through the ' line 21 and the passageway 29 into the rear end of the cylinder 1 ;i~; . .
at the start of the driving stroke, it acts against the rearward face of the head 16. The driving piston 4 remains in the position shown in Figure 1 until the pressure acting on the rearward face surrou~ded by the sealing lip becomes greater than the force i,~, holding the piston in the rearward position. Since the effective surface of the rearward face of the head 16 surrounded by the sealing lip 27 is substantially smaller than the opposite forward ~; face of the head, to effect the displacement of the driving piston ~; 4 away from the sealing lip 27 requires that the pressure of . "~
the compressed air as supplied through the passageway 29 must be , many times greater than the pressure used for effecting the return stroke of the piston As soon as the driving piston 4 starts to move away , from the sealing lip 27, the higher pressure compressed air ~?~:
flowing through the passageway 29 suddenly flows over the entire ~, ; 30 cross section of the bore 6 which corresponds to the area of the ,.,,.~ ,. .
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~ 08~939 i rearward face of the head 16. Due to the sudden increase in pressure acting on the head, the driving piston is abruptly ~ accelerated toward the forward end of the cylinder 1. However, ; the air introduced into the rearward end of the cylinder also acts against the annular surface 32 of the end wall 26 which laterally surrounds the sealing lip 27. The force exerted by the compressed air against the end wall 26 causes the cylinder 1 to move rearwardly against the biasing action of the compression spring 3. As the cylinder moves in the rearward direction, its end wall contacts the end wall or abutment 34 of the rear housing . . .~
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: part 18, the abutment having the shape of a ring shoulder. The ; ,., ,~ stop action provided by the abutment 34 insures that the spring ;,.,. :
~ 3 is not overly compressed.
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When the cylindex 1 is moved from the forward posikion of Figure 1 to the rearward position of Figure 2, a slot-shaped , . ,:,:
opening 33 opens between the front end face 9 of the cylinder ;j and the j~xtaposed counter-bearing 11 of the front housing part 8.
i~i The ope~ing 33 facilitates the outflow of the compressed air 'j located within the cylinder and forwardly of the piston head as ~`~, 20 the piston moves forwardly during its working stroke. The outflow ~; of the compressed air permits the driving piston 4 to reach its maximum acceleration values. The air flowing through the slot-shaped opening 33 flows outwardly from the device into the ambient : . ~
~ atmosphere through an aperture 35 in the rear part 18 of the . . .; . , .
houslng.
In Figure 2, the driving piston 4 has commenced the insertion of the fastening element 5 into the receiving material 36. Just before the fastening element 5 reaches its full depth ~;; bf penetration into the receiving material, the head 16 traverses ; 30 the transition from the forward end of the bore 6 into the recess . . .
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i 7. The lateral sur~a~e of the head 16 then ~ocks the ~low of :
alr into the slot-shaped opening 33. Accordingly, the air in the ~i recess 7 is trapped and forms an air cushion which decelerates the `~ still moving driving piston. During this part o~ the operation of the setting device, compressed air does not flow in either -~ direction through the passageway 23. The supply of compressed ~;~ air is regulated by the control circuit, mentioned previously.
; ` The supply of high pressure compressed air through the line 31 is then interrupted, permitting the cylinder 1 to be biased by the compression spring 3 and move in the forward direction back into sealing contact with the counter-bearing ll at the rearward ,.. ,.. ,j ~
end of the front housing part 8. Subsequently, the control circuit directs low pressure compressed air through the passageway 23 into the recess 7 for effecting the rearward or return stroke ~ of the driving piston 4 into the position illustrated in Figure l.
;~. In Figures 3 and 4 another setting device is illustrated .... ~
which is formed mainly of the same elements as the device in :~, Figures 1 and 2. Similar parts of both devices have been indicated ~' by the same reference numerals. Accordingly, in the following description only constructional and functional differences between ~;~ the two embodiments of the invention are explalned. In the embodiment of Figures 3 and 4, the housing 8 has a fixed tubular-i shaped member 42 extending rearwardly from the front housing part `~ 8 defining the lateral periphery of the cylinder containing the j t ~ ., driving piston 4 in the position shown in Figure 3. A cylindrical ~;~ shaped tubular-shaped part 43 telescopes movably over the part ` 42 and forms the lateral rear end 49 of the cylinder as well as '~`` its transverse end. As shown in Figures 3 and 4 the combination ,j.~ .~:
~ of the tubular-shaped parts 42 and 43 provides the overall .:, ;; ` 30 cylinder 41. At the forward end of the tubular-shaped part 42 . ~ .
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'`';'` ' . . ' 7~39 ~ an opening 44 is ~rovided, however, in the position shown in ; .
Figure 3 the openlng is closed laterally outwardly by the front .~: end of the movable tubular-shaped member 43, In the position of ;: the setting device shown in Figure 3, the front end 45 of the : . .
. tubular-shaped ~art 43 is pressed against the counter-bearing 11 ., .
.~ by means of a compression spring 47 laterally encircling the , ;: .
.;; tubular connection 22 and extending between the rearward face of ;..
~ the transverse end of the tubular part 43 and the transverse end .:,, ~.~; wall of an outer sleeve-like member 46 of the rear housing part.
.: 10 To improve the sealing action an elastic O-ring 48 is provided .. in the ounter-bearing 11. The tubular connection 22 to which .;,~ the high pressure working compressed air flows into the cylinder, . ~. , is formed i~tegrally with the transversely extending rear end wall 49 of the tubular-shaped member 43.
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. ; In the position shown in Figure 3, the driving piston 4 .,,j. ,.~, .
; . is held rearwardly against the sealing lip 27 by means of a low , . .. .
~l pressure compressed air introduced into the cylinder 41 through -`
, ~; the pai~sageway 23. When the higher pressure compressed air is ... . .
directed from the line 31 through the passageway 29 into the rearward end of the cylinder, the piston is lifted off the sealing lip 27, as has been described with regard to Figures 1 and 2.
f;`'." With the higher pressure compressed air flowing across the full , ~:
~ cross sectional area within the cylinder located rearwardly of ~: . the head 16 of the piston, the driving piston is accelerated -~ forwardly through the inner tubular-shaped member 42. And, at -:
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. the same time, the outer tubular shaped member 43 is moved rear-wardly relative to the housing, that is, relative to the inner ; :.i ,, .
~ tubular-shaped member 42 and the outer sleeve-like member 46.
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~ The tubular shaped member 43 moves rearwardly because the working , .: .
compressed air in the cylinder overcomes the biasing effect of the ~`,',', . . - 15 -.
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spring 47. The compressed air acts ~gainst the annul~r shaped ,~ surface 51 on the transverse end waLl 49 of the tubular-shaped ... ~ member 43. With the rearward movement of the tubular-shaped :;. ;.
.. ~ member 43 the position of the setting device is as illustrated ~ in Figure 4 and the opening 44 aligned with the slot provided ~, between the front end 45 and the juxtaposed counter-bearing 11 permits the air within the cylinder ahead of the piston to flow outwardly through the aperture 35 to the ambient atmosphere about the setting device.
To prevent over-compression of the spring 47 during the rearward movement of the tubular-shaped member 43, the member is . .,, j., ~ , . . .
ntercepted ln lts rearward movemen~ by a shoulder-llke abutment 53 formed by the outer casing part 46. A sealing ring 54 is ` ^~ provided in the inner surface of the tubular-shaped member 43 so that it contacts the outer surface of the other tubular-shaped ;, ~;.......... member 42 to prevent any bypassing flow of the medium located i. ,~;, '~i in front of or behind the piston head 16.
!; ` . Having described what is believed to be the best mode . ., . ~
`~. by which the invention may be performed, it will be seen that the ~ 20 invention may be particularly defined as follows:
:";"` A compressed air operated setting device comprising a ~....
.. housing, wall means within said housing and forming in combination ;. therewith an axially extending cylinder having a first end and a : ,.
second end spaced apart in the axial direction of said cylinder, ~': a driving piston movably mounted in said cylinder and axially ; displaceable therein, means for supplying compressed air into said ~" cylinder for displacing said driving piston in the direction from ~. the first end toward the second end of said cylinder, wherein the `~` ; improvement comprises that said meani for supplying compressed i~- 30 air is attached to said wall means at the first end of said , . ~ . .
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cylinder and sald wall means being movably displaceable relative to said housing, said housing forming a discharge opening from said cylinder to the exterior of said housing and the discharge opening being located at a position spaced from the first end '';: ! .`':, ~
;~ - toward the second end of said cylinder, said wall means being ~ movable within said housing between a first position closing off -~ said discharge opening and a second position opening said discharge ~`;- opening so that air within said cylinder between said driving .`~ piston and the second end of said cylinder can be discharged to the exterior of said housing when said driving piston is displaced in the direction from the first end toward the second end of ~` said cylinder.
; ; The invention further comprises a compressed air . ., operated setting device, having the foregoing features and includ-"~ ing biasing means located within said housing in contact with said wall means for biasing said wall means into the first ` position.
; ~ The invention further comprises a compressed air operated setting device, having the foregoing features and wherein , 20 said biasing means comprises a compression spring.
. :, ; ~ The invention further comprises a compressed air operated setting device, having the foregoing features and wherein said housing includes a bearing surface extending transversely of the axial direction of said cylinder and said wall means being pressed against said bearing surface by said ~. ., ~ , ,~;, biasing means in the first position of said wall means.
While specific embodiments of the invention have been r, . ' .
~, shown and described in detail to illustrate the application of the inventive principles, it will be understood that the inven-~,. t`
;~`t`,-!` 30 tion may be embodied otherwise without departing from such `~ principles.
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The present invention is directed to ~ compre~ed air operated setting device includiny a driving piston displaCeable through a cylinder by means of compressed air supplied into the cylinder. Further, the invention concerns an arrangement of the - cylinder-permitting the discharge of air from in front of the piston as it is driven through the cylinder.
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The effectiveness of compressed air operated setting ::, devices depends particularly on the kinetic energy imparted . .
r'~.' to the driving piston. The kinetic energy is directly related , :..
to the velocity imparted to the driving piston. In other words, the greater the working stroke-speed of the driving piston, the greater is the kinetic energy of the piston.
.,-:~ Compressed air operated setting devices are known in .: ;
which the driving piston has a head on its rear end which is mounted in sealed engagement with the guide bore in the cylinder.
Further, the piston includes a shank extending forwardly from the head, that is, it extends in the driving direction of the piston.~ The shank projects outwardly from the cylinder in the driving directionc After each driving stroke is effected, the ,;,: ,, ~ 20 piston is returned to its rearward position within the cylinder -;
by a supply o~ low pressure air. The low pressure air is introduced into the cylinder from a supply source at a location forwardly of the piston head after it has completed the driving action. The driving piston is maintained in ~he rear end of the cylinder by the low pressure air. Furt~er, the supply of air at the head of the piston is maintained after its return stroke has been effected. Subsequently, on the next driving stroke air , compressed at a higher pressure is introduced into the cylinder ~;:.
~`1 rearwardly of the driving piston. This supply of higher pressure ;~ 3a air directed against the rearward end of the piston head accelerates ''`':~'`.'~
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~;` the piston ~orwarclly so th~t lt can per~orm the de~lred work.
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While the use of these various measures ha~ increased the speed of the driving pi~ ton, for carrylng out certain work, such as setting fastening elements into hard receiving materials, --,:..................................................................... .
'~','' the piston speed is still too low. The low speeds are caused ,"'~ by the air present in the front of the driving piston during its , - , working st~oke. This air is not-discharged rapidly enough from :.~
~'" the cylinder with the results that an air cushion is present ~',,, acting against the acceleration of the piston.
' This disadvantage in prior art devices resides in the . . .: . .
~;``,~ fact that the dlscharge flow of air from the cylinder passes ~-' through the supply'channel for low pressure, return air in the forward end of the cylinder. The supply channel provides the air ~ ~, . . .
i;"' for displacing the driving piston to the rear end of the cylinder.
,'~',' The operation of the supply channel is regu;lated by a special ~ ".,~ .
~'~, control including mechanical valves. Such an arrangement for discharging the air is unsatisfactory, because of the amount . . i~.: . -`',~',~, of air ~o be exhausted and the reaction time of the valves.
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~-' Morsover, such mechanical valves are very cumbersome,and expensive .~ ., ~ .
~, 20 and have a tendency to malfunction or operate improperly, Ther,efore, the primary object of the present invention ~,"` is to provide a compressed air operated setting device in which the air ahead of the piston during its working stroke is discharged in an accelerated manner without involving the use of any complex mechanisms which have a tendency to malfunction.
In accordance with the present invention, this object ~, is achieved by constructing a portion of the cylinder in the :;~ device for axial movement relative to the housing of the device ,i,` so that such movement effects the opening of outlets for exhausting the gaseous medium during the working stroke of the piston.
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The portion of -the cylinder through which the ga~eous medium is supplied ~or moving the piston forwardly~ i5 forme~ as ".,. ~
a tubular shaped member closed at the rear by an end wall forming a closure for the rearward end of the cylinder bore. The means . .
for introducing the compress~d air into the cylinder for driving the piston is connected to the end wall.
. .
If compressed air is introduced into the cylinder behind the piston with the piston located in its rearward position in the cylinder, the piston is accelerated forwardly and, at the same time, the rear end wall of the cylinder through which the air is ~. i charged is displaced rearwardly relative to the housing. As the portion of the cyIinder moves in the rearward direction, one or a number of discharge outlets open through the cylinder and the housing adjacent the forward end of the cylinder. The air or other gaseous medium within the cylinder ahead of the piston is dis-charged to the exterior of the setting device, that is, to the ambient atmosphere.
. ., With this arrangement, it is necessary for the channel which supplies the gaseous medium for moving the piston rearwardly, ~' 20 to exhaust the medium in front of the piston during its working ~;
; stroke. Further, the one-way function of the valves in the ~` control circuit associated with the supply channel afford a ~; trouble-free and simple construction of these elements. The size of the discharge openings for the setting device can be ~` selected as any suitable size. Further, their arrangement and `i, configuration can be varied in accordance with the conditions ' experienced. For-example, the outlet openings can be provided ~ .
~; in the cylinder and in the housing which encloses the cylinder ~` so that the openings in the non-operatingcondition of the device are closed. When the movable portion of the cylinder is displaced . . - .
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the outlets are opened. In a particularly effective arrangement `~ of the present invention, the discharge outlet is located adjacent to the end of the cylinder through which the medium is supplied -~; for moving the drivlng piston rearwardly. Furthermore, the j : width of the gap or slot providing the discharge outlet may . ~ .
adapt itself to the working pressure so that the outlet opening ` becomes automatically larger with increasing working pressure , ...
^ due to increased displacement of ~he movable cylinder part.
To maintain the discharge outlets closed under ordinary .: .
t 10 conditions, a biasing means can be used which maintains the movable portion of the cylinder in a forward position. Such ~s biasing means assures that the movable cylinder part is returned ; to the closing position after the completion of the driving : i';
operation, The force exerted by the biasing means should be greater than the force asserted in returning the piston to its rearward position within the cylinder so that the movable cylinder part can be returned to the closing position.
Advantageously, the biasing means can be a compression i. r.. : ., ~
spring such as a helical spring. The particular advantage of a compression spring resides in the fact that it is subject to a much lower degree of overtension as compared to other types of springs, such as a spring subject to drawing forces. ~lowever, as ~ a general principle it is also possible to use a compressed air :''t`"' or gas cushion as the biasing means in place of a compression spring.
` Another feature of the present invention is that the movable-part of the cylinder is pressed against a bearing surface :';,~li.................................................................. ~
on a housing for alosing the discharge outlets with the pressing ~' action being effected by the biasing means so that a sealing action is effected. In addition, the movable portion of the cylinder .. . ....
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3g also includes the connection ~or supplyiny ~he compre~sed air or effecting the working stroke of -the piston. Accordingly, when the movable par-t of the cylinder i~ displaced rearwardly an annular gap is provided between the forward end of the cylinder part and the housing affording a connection between the interior of the cylinder and the discharge openings through the housing.
The sealing action provided between the housing and the movable cylinder part facilitates the buildup of the pressure in the cylinder head of the piston for effecting its return stroke.
lQ To provide a particularly effective sealing action, it is preferable if at least one of the contacting surfaces affording the seal includes a sealing element. An O-ring member formed of oil-resistant rubber is particularly suitable for use as a sealing element.
Where high working pressures are used in the setting . ~ . . .
device, it is advantageous to limit the movement of the movable cylinder part toward the r~ar end of the housing. By limiting ,,,.~:, `the mou~ment, a complete compression of the biasing means is ~ prevented. Accordingly, the housing provides an abutment or ~ 20 stop surface which limits the rearward movement of the movable cylinder part. Such an abutment or stop can be constructed in ;i~ I
i~ the form of an annular or ring-shaped shoulder. Further, stop ;~
pins or other abutment members can be used in limiting the ~ movements of the cylinder part. Still another feature of the .~ invention is the provision of a sealing lip about an opening `~ through an end wall of the cylinder through which compressed air ; is supplied for driving the piston. This sealing lip cooperates with the driving piston when the piston is in its rearward `; position.
This arrangement of the opening which supplies the ~ .;
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working compressed air into the cylinder aEfords a very ~imple valve arrangement.
, `~ During operation, the sealing effect between the annular ; sealing lip and the rearward facing end of the drive piston is maintained until the working pressure supplied through the rear end-of the cylinder reaches a higher force on the drive piston than the force which effected the displacement of the piston to ,; !.
-' the rearward end of the cylinder. Subsequently, with increasing .....
~; pressure of the compressed air, the drive piston starts to accelerate in the forward direction. The acceleration is considerably facilitated by the discharge of the medium located within the cylinder and forwardly of the piston head. The ~ c,:l `~ medium flows through the discharge outlets opening through the ,`~ cylinder and the housing to the ambient atmosphere. The t~
compressed air for driving the piston can be supplied directly from a compressor or from an intermediate storage vessel.
It is advantageous if the rearwardly facing end of the ~: ; piston head has a outside diameter which is larger than the outside . .
diameter of the sealing lip. Since the sealing lip, relative t 20 to the juxtaposed base of the piston head, encloses only a small circular surface on the head, the pressure of the working compressed air supplied into the cylinder at its rearward end for the driving stroke must be many times greater than the low pressure air maintaining the piston head in its rearward position in the cylinder. By overcoming this differential, the high pressure air can displace the drive piston from the sealing lip.
As soon as the sealing effect is overcome, however, the high pressure compressed air flows instantaneously over the entire cross section of the bore within the cylinder and acts, on one hand, over the entire rear end face of the piston head and, on .
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` th~ o-ther hand, on tiie ~xta~osed transverse end ~ace of the - cylinder t.Arough whlch the working compressed dir is supplied.
~ As ~ result, there is an instant or sudden acceleration of the .
drive piston ln the forward direction and a rearward movement of : the movable cylinder part relative to the housing. Due to the - rearward-movement of the cylinder part, the dis~harge outlets are opened and the drive piston can move forwardly through the ~ :, ,. . ~
cylinder without interference.
;~ Concerning the wear of the drive piston and the cylinder parts, i~ has been noted that it is advantageous to form the movable cylinder part through which the compressed air is supplied ; into the cylinder, in the form of a tubular-shaped member which ~,~ laterally encloses a guide tube or sleeve-like member forming the axially extending wall of the cylinder. The tubular-shaped ~-movable cylinder part is axially displaceable relative to the sleeve-like member portion of the cylinder. At its forward end, .~;:; .
~ the sleeve-like member is connected to the housing while its ~,i rear e~d is closed by a transverse end wall formed on the tubular-shaped member of the movable cylinder part. At its forward end, the sleeve-like member has one or several recesses or perforations permitting the medium within the cylinder at the head of the piston to escape through discharge openings formed ir. the housing when the tubular-shaped member is displaced rearwardly. A sealing member can be provided between the sleeve-like member and the movable tubular shaped member to prevent any possible outflow of the compressed air supplied into the cylinder either ahead of or behind the-drlving piston head.
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;~; In setting devices of the type described above, it is ~ advantageous if the drive piston, just prior to completing the '` 30 driving procedurer is "caught" or slowed down as it approaches ~,..: ;.~
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..,~;, ~-^ -th~ forward end of the cylinder. Accordingly, an extension of the bore within the cylinder is provided by the housing. With ~,:
such an arrangement, lt is possible to exhaust any gaseous '~x, . -;
medium ahead of the drive piston and thus provide it with a ~laximum acceleration while providing a braking action for the piston as ~, .
it reaches the forward end of the cylinder and travels beyond ~; the discharge outlets for the medium. The medium trapped in the ~i- forward extension of the cylinder provides an air cushion. Advan-"V! ' :' ~"` tageously, the housing for the setting device includes a passageway for supplying the medium into the cylinder which effects the rearward displacement of the drive piston. This supply passageway r,~"
is located so that it assures a flow of compressed air in front of the forward end face of the head even when it is in its forward position within the cylinder. As a result, after each driving movement of the piston, it will be reliably displaced ~ p"~.
to the rearward end of the cylinder~
- The various features of novelty which characterize ~ the in~ention are pointed out with particularity in the claims ;~ annexed to and forming a part of this disclosure~ For a ~. i i 20 better understanding of the invention, its operating advantages ,j~ and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the ~, invention.
i.~,: ;,, ~; IN THE DRAWINGS:-Figure 1 is an axially ex-tending sectional view through ).,.,,.,;.,,.i a compressed air operating setting device embodying the present ,~.
~ invention with the drive piston located in its rearward position;
. .
'~"!"~ Figure 2 is a view similar to Figure 1 but with the setting device in the working position for inserting a fastening ~'."' ~,''~' .
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element into receiving materials;
,: .,;, ,- Figure 3 is an axially extending sectional view of , ,~ r, .
~`` another embodiment of the setting device with the drive piston .
located in its rearward position, and, Figure 4 is a view similar to Figure 3 but with the ~- drive piston displaced forwardly toward its forward end position.
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In Figures 1 and 2 a compressed air operated setting device is illustrated including an axially extending cylinder 1.
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~ Part of the structure forming the cylinder 1 is axially movable -;.. , :
relative to the housing 2 of the setting device. For assembly . - - . .:
~ I purposes, the housing consists of two parts, the front housing .. ~ . .
portion 8 and the rear housing part 18. The cylinder 1 which combines with the front housing part 8 in forming the overall ., .
' cylinder through which the driving piston 4 is displaceable, ; ~ consists of an axially extending tubular shaped part 6a and a . .,. I; ~ .
- transversely extending end wall 26 closing off the rearward end :.
i of the tubular-shaped part 6~ The cylinder 1 is pressed by a ~ biasi~ member or spring 3 orwardly within the housing 2. As i viewed in Figuxes 1 and 2, the driving or working direction of ~i,;. ~ . .
~;l 20 the piston 4 is to the left, that is, the direction in which the fastening element 5 is driven out of the housing. As can be seen in Figures 1 and 2, the driving piston is movably displaceable through the cylinder and the bore 14 in the forward part 8 of the housing ~or driving a fastening element 5 into a receiving material 36, note Figure 2. During the driving action the fast-ening element 5 is guided within the bore 14 through the forward ~iii part 8 of the housing.
m The bore 6 formed within the cylinder is open at its orward end and extends into the corresponding recess 7 in the `'~ 30 rearward end of the forward housing part 8. Due to the biasing ;~
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793g i action of the compression spring 3, khe ~ront end 9 of the cylinder .~: 1 is held against the juxtaposed rear end surface 11 of the forward housing part 8. sore 6, in combination with the recess 7 which has the same diameter thus provides th~ bore through which the .~ piston head is displaceable. The juxtaposed surface 11 of the .
~-- front housing part 8 relative to the front end 9 of the cylinder ~'. forms a counter-bearing. To provide an increased sealing effect, .~ the surface or counter-bearing 11 includes a sealing element 12 in the form of an elastic O-ring.
The driving piston 4 includes a shank 13 extending ,.,~.;, -axially forwardly from its head 16. The shank is movably .i: supported within the bore 14 in the forward housing part 8 and .~ forms a seal between the cylinder bore 6 and the outlet bore 14.
. ~ Sealing ring 15 is provided at the rearward end of the bore 14 `~ in sealing engagement with the peripheral surface of the shank 13.
,` While the shank 13 is guided within the bore 14, the head 16 of -~;., the pi~ton 4 is held in sliding engagement within the guide bore .6 in t~e cylinder. Sealing element 17 is provided around the circumferential periphery of the head 16 affording a sealing ac-tion with the wall surface of the cylinder forming the bore 6.
The rearward housing part 18 is screwed onto the rear-ward end of the front housing part 8 by means of a threaded connection 19. The rear housing part 18 includes a generally .;. ~
;i cylindrical tubular-shaped portion or member laterally surrounding and spaced outwardly from the cylinder 1 with a transversely extending end wall 34. A shoulder 21 on the forward end of the . - cylinder 1, and a compressed air supply passage tu~e 22 extending rearwardly from the rear end 26 of the cylinder 1, provides ` mounting means or support for the cylinder 1 within the housing part 18. Further, the housing part 18 encloses the compression ., , . i ~'i`; .
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~. spring 3 with ~le rearward end oE the spring bearing against the inside face of -the rear housing part 18 while the front end of ~ the spring bears against the shoulder 21 on the cylinder 1.
.. Extending transversely through the rearward end of .:: - housing part 8 and the forward end of housing part 18 is a :
. - passageway 23 which opens into the recess 7, closing the forward :
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.end of the bore 6. The outer end of the passageway 23 is connected to a supply conduit 24 which extends through a handle 25. Though not shown for purposes of simplicity, a control circuit is con- -~a 10 nected to the setting device shown on Figure 1. By means of ;;~ the control circuit, a supply of low pressure compressed air ~ can be introduced through the conduit 24 into the passageway 23: ~., ~ , '. and then into the recess 7 at the forward end of the bore 6 where . ,,,~. .
it enters ahead or in front of the forwardly directed face of the .: head 16 of the drive piston 4. With this low pressure compressed air introduced into the front end of the cylinder 1, the drive ~ piston 4 can be displaced rearwardly, after having effected a driving~stroke, into the xearward position shown in Figure 1 `~'.i When the driving piston is returned rearwardly ~hrough,,~, .. j .
~:. 20 the cylinder 1 with its head contacting the rear end wall of the .. ; cylinder, it is ready for the next driving stroke and the supply ;! .
~ of low pressure compressed air is maintained to hold the piston .
`'!'~'':'' in place. Extending concentrically about the opening of tube 22 :~
` through the rear end 26 of the cylinder 1 is an annular sealing lip 27 which projects forwardly from the rear end wall 26 of the . cylinder. The cross sectional surface of the rearward face of the-head 16 encircled by the sealing lip 27 is many times smaller than the total cross section of the rearward face of head 16.
To improve the sealing action between the head 16 and the sealing lip 27, a sealing disc 28 is recessed into the . .: - , ., ;.~
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rearward fac~ o~ the ~l~ad, SealLng di~C 28 lg m~d~ of an elastic or a resilient material usually employe~ for such purposes. To assure that the pressure acting against the ~orward face of the head does not break the seal between the forward end of the ~, cylinder l and the surface-or counterbearing 11, the force exerted ii by the-compression spring 3 should be greater than the force displacing the head 16 to the rearward end of the cylinder.
The tubular connection 22 fixed to the rear end wall 26 of the cylinder forms a passageway 29 which opens through the -center of the annular sealing lip 27 into the cylinder 1. At its rear end the tubular connection 22 is joined to a compressed air line 31 for supplying the working medium into the passageway ~- 29. When the working medium is permitted to flow through the ' line 21 and the passageway 29 into the rear end of the cylinder 1 ;i~; . .
at the start of the driving stroke, it acts against the rearward face of the head 16. The driving piston 4 remains in the position shown in Figure 1 until the pressure acting on the rearward face surrou~ded by the sealing lip becomes greater than the force i,~, holding the piston in the rearward position. Since the effective surface of the rearward face of the head 16 surrounded by the sealing lip 27 is substantially smaller than the opposite forward ~; face of the head, to effect the displacement of the driving piston ~; 4 away from the sealing lip 27 requires that the pressure of . "~
the compressed air as supplied through the passageway 29 must be , many times greater than the pressure used for effecting the return stroke of the piston As soon as the driving piston 4 starts to move away , from the sealing lip 27, the higher pressure compressed air ~?~:
flowing through the passageway 29 suddenly flows over the entire ~, ; 30 cross section of the bore 6 which corresponds to the area of the ,.,,.~ ,. .
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~ 08~939 i rearward face of the head 16. Due to the sudden increase in pressure acting on the head, the driving piston is abruptly ~ accelerated toward the forward end of the cylinder 1. However, ; the air introduced into the rearward end of the cylinder also acts against the annular surface 32 of the end wall 26 which laterally surrounds the sealing lip 27. The force exerted by the compressed air against the end wall 26 causes the cylinder 1 to move rearwardly against the biasing action of the compression spring 3. As the cylinder moves in the rearward direction, its end wall contacts the end wall or abutment 34 of the rear housing . . .~
.,,.,. :
: part 18, the abutment having the shape of a ring shoulder. The ; ,., ,~ stop action provided by the abutment 34 insures that the spring ;,.,. :
~ 3 is not overly compressed.
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When the cylindex 1 is moved from the forward posikion of Figure 1 to the rearward position of Figure 2, a slot-shaped , . ,:,:
opening 33 opens between the front end face 9 of the cylinder ;j and the j~xtaposed counter-bearing 11 of the front housing part 8.
i~i The ope~ing 33 facilitates the outflow of the compressed air 'j located within the cylinder and forwardly of the piston head as ~`~, 20 the piston moves forwardly during its working stroke. The outflow ~; of the compressed air permits the driving piston 4 to reach its maximum acceleration values. The air flowing through the slot-shaped opening 33 flows outwardly from the device into the ambient : . ~
~ atmosphere through an aperture 35 in the rear part 18 of the . . .; . , .
houslng.
In Figure 2, the driving piston 4 has commenced the insertion of the fastening element 5 into the receiving material 36. Just before the fastening element 5 reaches its full depth ~;; bf penetration into the receiving material, the head 16 traverses ; 30 the transition from the forward end of the bore 6 into the recess . . .
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i 7. The lateral sur~a~e of the head 16 then ~ocks the ~low of :
alr into the slot-shaped opening 33. Accordingly, the air in the ~i recess 7 is trapped and forms an air cushion which decelerates the `~ still moving driving piston. During this part o~ the operation of the setting device, compressed air does not flow in either -~ direction through the passageway 23. The supply of compressed ~;~ air is regulated by the control circuit, mentioned previously.
; ` The supply of high pressure compressed air through the line 31 is then interrupted, permitting the cylinder 1 to be biased by the compression spring 3 and move in the forward direction back into sealing contact with the counter-bearing ll at the rearward ,.. ,.. ,j ~
end of the front housing part 8. Subsequently, the control circuit directs low pressure compressed air through the passageway 23 into the recess 7 for effecting the rearward or return stroke ~ of the driving piston 4 into the position illustrated in Figure l.
;~. In Figures 3 and 4 another setting device is illustrated .... ~
which is formed mainly of the same elements as the device in :~, Figures 1 and 2. Similar parts of both devices have been indicated ~' by the same reference numerals. Accordingly, in the following description only constructional and functional differences between ~;~ the two embodiments of the invention are explalned. In the embodiment of Figures 3 and 4, the housing 8 has a fixed tubular-i shaped member 42 extending rearwardly from the front housing part `~ 8 defining the lateral periphery of the cylinder containing the j t ~ ., driving piston 4 in the position shown in Figure 3. A cylindrical ~;~ shaped tubular-shaped part 43 telescopes movably over the part ` 42 and forms the lateral rear end 49 of the cylinder as well as '~`` its transverse end. As shown in Figures 3 and 4 the combination ,j.~ .~:
~ of the tubular-shaped parts 42 and 43 provides the overall .:, ;; ` 30 cylinder 41. At the forward end of the tubular-shaped part 42 . ~ .
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'`';'` ' . . ' 7~39 ~ an opening 44 is ~rovided, however, in the position shown in ; .
Figure 3 the openlng is closed laterally outwardly by the front .~: end of the movable tubular-shaped member 43, In the position of ;: the setting device shown in Figure 3, the front end 45 of the : . .
. tubular-shaped ~art 43 is pressed against the counter-bearing 11 ., .
.~ by means of a compression spring 47 laterally encircling the , ;: .
.;; tubular connection 22 and extending between the rearward face of ;..
~ the transverse end of the tubular part 43 and the transverse end .:,, ~.~; wall of an outer sleeve-like member 46 of the rear housing part.
.: 10 To improve the sealing action an elastic O-ring 48 is provided .. in the ounter-bearing 11. The tubular connection 22 to which .;,~ the high pressure working compressed air flows into the cylinder, . ~. , is formed i~tegrally with the transversely extending rear end wall 49 of the tubular-shaped member 43.
f~
. ; In the position shown in Figure 3, the driving piston 4 .,,j. ,.~, .
; . is held rearwardly against the sealing lip 27 by means of a low , . .. .
~l pressure compressed air introduced into the cylinder 41 through -`
, ~; the pai~sageway 23. When the higher pressure compressed air is ... . .
directed from the line 31 through the passageway 29 into the rearward end of the cylinder, the piston is lifted off the sealing lip 27, as has been described with regard to Figures 1 and 2.
f;`'." With the higher pressure compressed air flowing across the full , ~:
~ cross sectional area within the cylinder located rearwardly of ~: . the head 16 of the piston, the driving piston is accelerated -~ forwardly through the inner tubular-shaped member 42. And, at -:
;,~ ,:
. the same time, the outer tubular shaped member 43 is moved rear-wardly relative to the housing, that is, relative to the inner ; :.i ,, .
~ tubular-shaped member 42 and the outer sleeve-like member 46.
'i;'~
~ The tubular shaped member 43 moves rearwardly because the working , .: .
compressed air in the cylinder overcomes the biasing effect of the ~`,',', . . - 15 -.
' ;'`'.
, . ~ .
: ,; :j, ~.~
... . .
.`.
.......
spring 47. The compressed air acts ~gainst the annul~r shaped ,~ surface 51 on the transverse end waLl 49 of the tubular-shaped ... ~ member 43. With the rearward movement of the tubular-shaped :;. ;.
.. ~ member 43 the position of the setting device is as illustrated ~ in Figure 4 and the opening 44 aligned with the slot provided ~, between the front end 45 and the juxtaposed counter-bearing 11 permits the air within the cylinder ahead of the piston to flow outwardly through the aperture 35 to the ambient atmosphere about the setting device.
To prevent over-compression of the spring 47 during the rearward movement of the tubular-shaped member 43, the member is . .,, j., ~ , . . .
ntercepted ln lts rearward movemen~ by a shoulder-llke abutment 53 formed by the outer casing part 46. A sealing ring 54 is ` ^~ provided in the inner surface of the tubular-shaped member 43 so that it contacts the outer surface of the other tubular-shaped ;, ~;.......... member 42 to prevent any bypassing flow of the medium located i. ,~;, '~i in front of or behind the piston head 16.
!; ` . Having described what is believed to be the best mode . ., . ~
`~. by which the invention may be performed, it will be seen that the ~ 20 invention may be particularly defined as follows:
:";"` A compressed air operated setting device comprising a ~....
.. housing, wall means within said housing and forming in combination ;. therewith an axially extending cylinder having a first end and a : ,.
second end spaced apart in the axial direction of said cylinder, ~': a driving piston movably mounted in said cylinder and axially ; displaceable therein, means for supplying compressed air into said ~" cylinder for displacing said driving piston in the direction from ~. the first end toward the second end of said cylinder, wherein the `~` ; improvement comprises that said meani for supplying compressed i~- 30 air is attached to said wall means at the first end of said , . ~ . .
{~,;
~ 16 -., . .,:
: :"
:....
::
: , .
' - .
., .
:
" ;:
. .... .
3~ ~
., .
~.
`;:;
cylinder and sald wall means being movably displaceable relative to said housing, said housing forming a discharge opening from said cylinder to the exterior of said housing and the discharge opening being located at a position spaced from the first end '';: ! .`':, ~
;~ - toward the second end of said cylinder, said wall means being ~ movable within said housing between a first position closing off -~ said discharge opening and a second position opening said discharge ~`;- opening so that air within said cylinder between said driving .`~ piston and the second end of said cylinder can be discharged to the exterior of said housing when said driving piston is displaced in the direction from the first end toward the second end of ~` said cylinder.
; ; The invention further comprises a compressed air . ., operated setting device, having the foregoing features and includ-"~ ing biasing means located within said housing in contact with said wall means for biasing said wall means into the first ` position.
; ~ The invention further comprises a compressed air operated setting device, having the foregoing features and wherein , 20 said biasing means comprises a compression spring.
. :, ; ~ The invention further comprises a compressed air operated setting device, having the foregoing features and wherein said housing includes a bearing surface extending transversely of the axial direction of said cylinder and said wall means being pressed against said bearing surface by said ~. ., ~ , ,~;, biasing means in the first position of said wall means.
While specific embodiments of the invention have been r, . ' .
~, shown and described in detail to illustrate the application of the inventive principles, it will be understood that the inven-~,. t`
;~`t`,-!` 30 tion may be embodied otherwise without departing from such `~ principles.
,,. :. j ~ 17 -. `,.'~?
,........................................... .
"~
': ":`, :,:',',,' .; . . ' ` , .` : `~``
.~ : . '
Claims (14)
1. A compressed air operated setting device for driving fastening elements into a receiving material, comprising a housing, wall means positioned within said housing and forming in combi-nation therewith an axially extending cylinder having a first end and a second end spaced apart in the axial direction of said cylinder, a driving piston movably mounted in said cylinder and axially displaceable therein for driving fastening elements from said housing, means for supplying compressed air into said cylinder for displacing said driving piston in the direction from the first end toward the second end of said cylinder for driving the fastening elements, wherein the improvement comprises that said means for supplying compressed air is attached to said wall means at the first end of said cylinder and said wall means being movably displaceable relative to said housing, said housing forming a discharge opening from said cylinder to the exterior of said housing and the discharge opening being located at a position spaced in the axial direction from the first end toward the second end of said cylinder, said wall means being movable within said housing between a first position closing off said discharge opening and a second position opening said discharge opening so that air within said cylinder between said driving piston and the second end of said cylinder can be discharged to the exterior of said housing when said driving piston is displaced in the direction from the first end toward the second end of said cylinder.
2. A compressed air operated setting device, as set forth in Claim 1, including biasing means located within said housing in contact with said wall means for biasing said wall means into the first position.
3. A compressed air operated setting device, as set forth in Claim 2, wherein said biasing means comprises a compression spring.
4. A compressed air operated setting device, as set forth in Claim 2, wherein said housing includes a bearing surface extending transversely of the axial direction of said cylinder and said wall means being pressed against said bearing surface by said biasing means in the first position of said wall means.
5. A compressed air operated setting device, as set forth in Claim 4, wherein said wall means has a first surface arranged to contact said bearing surface in the first position, and a sealing element is provided in one of said bearing surface and said first surface to provide a seal therebetween in the first position of said wall means.
6. A compressed air operated setting device, as set forth in Claim 2, wherein said housing forms an abutment adjacent the second end of said cylinder and arranged to be contacted by said wall means in the second position thereof with said wall means being spaced from said abutment in the first position.
7. A compressed air operated setting device, as set forth in Claim 1, wherein said wall means includes an end wall extending transversely of the axial direction of said cylinder and located at the end of said wall means closer to the first end of said cylinder, said end wall having an opening therethrough extending in the axial direction of said cylinder, said means for supplying compressed air being connected through said opening in said end wall for directing the compressed air into said cylinder, an annular sealing lip formed on the face of said end wall directed into said cylinder, said lip encircling said opening in said end wall and projecting outwardly from said end wall and said sealing lip arranged to contact said driving piston when said driving piston is displaced axially to the first end of said cylinder.
8. A compressed air operated setting device, as set forth in Claim 7, wherein said driving piston has a rear end facing the first end of said cylinder and a front end facing the second end of said cylinder, and the circumferential periphery of the rear end of said driving piston is spaced radially outwardly from said sealing lip.
9. A compressed air operated setting device, as set forth in Claim 1 wherein said housing comprises a sleeve-like section forming at least a portion of the axially extending wall of said cylinder, said wall means comprises a tubular-shaped member laterally enclosing said sleeve-like section and having an end wall extending transversely of the axis of said cylinder forming a closure for the end of said tubular-shaped member and also forming the first end of the said cylinder, said tubular-shaped member being axially movable relative to said sleeve-like section.
10. A compressed air operated setting device, as set forth in Claim 1, wherein said housing forms a bore extending axially from and in communication with the second end of said cylinder, said driving piston having a head arranged within and disposed in sliding contact with said cylinder and a shank extending from said head and being movably displaceable through said bore.
11. A compressed air operated setting device, as set forth in Claim 1, wherein said housing has a passageway extending therethrough opening into the second end of said cylinder, said passageway arranged to receive a supply of compressed air at a lower pressure than used for driving said driving piston for displacing said driving piston toward the second end of said cylinder when the supply of driving compressed air delivered into the first end of said cylinder is cut off.
12. A compressed air operated setting device, as set forth in Claim 11, wherein said discharge opening through said housing is spaced from and located adjacent to the second end of said cylinder and said passageway opens into said cylinder at the second end thereof.
13. A compressed air operated setting device, as set forth in Claim 2, wherein said housing comprises a first tubular-shaped member having a first transverse end wall located adjacent to the first end of said cylinder, said wall means including a second tubular-shaped member co-axial with and spaced radially inwardly from said first tubular-shaped member and having a second transverse end wall, said second tubular-shaped member forming the axially extending wall of said cylinder and said second transverse wall forming the first end of said cylinder, said second tubular-shaped member being open at its opposite end from said second transverse end wall and being axially displaceable relative to said first tubular-shaped member.
14. A compressed air operated setting device, as set forth in Claim 13, wherein said biasing means comprises a compression spring located between said first and second tubular-shaped member, said compression spring extending in the axial direction of said cylinder and bearing at one end against said first transverse end wall and at the other end thereof against said second tubular-shaped member .
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2651529.7 | 1976-11-11 | ||
| DE19762651529 DE2651529A1 (en) | 1976-11-11 | 1976-11-11 | COMPRESSED AIR SETTING DEVICE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087939A true CA1087939A (en) | 1980-10-21 |
Family
ID=5992948
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA290,526A Expired CA1087939A (en) | 1976-11-11 | 1977-11-09 | Compressed air operated setting device |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS5360772A (en) |
| AT (1) | AT363875B (en) |
| AU (1) | AU3050277A (en) |
| BE (1) | BE860270A (en) |
| CA (1) | CA1087939A (en) |
| CH (1) | CH624335A5 (en) |
| DE (1) | DE2651529A1 (en) |
| FI (1) | FI62969C (en) |
| FR (1) | FR2370555A1 (en) |
| GB (1) | GB1555901A (en) |
| IT (1) | IT1088132B (en) |
| MX (1) | MX144290A (en) |
| NL (1) | NL7712339A (en) |
| SE (1) | SE7712610L (en) |
| ZA (1) | ZA776053B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11400574B2 (en) | 2016-06-21 | 2022-08-02 | Techtronic Power Tools Technology Limited | Gas spring fastener driver |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE537833A (en) * | 1954-05-03 | |||
| US2944522A (en) * | 1957-02-25 | 1960-07-12 | Fastener Corp | Fastener driving apparatus |
| FR1378523A (en) * | 1963-12-21 | 1964-11-13 | Fastener Corp | Device for driving staples |
| US3438449A (en) * | 1967-04-10 | 1969-04-15 | Arthur J Smith | Pneumatically operated power driver |
| US3604311A (en) * | 1968-07-19 | 1971-09-14 | Umberto Monacelli | Compressed air nailing machine |
| BE789035A (en) * | 1971-12-22 | 1973-01-15 | Senco Products | PNEUMATIC TOOL FOR DRIVING FASTENERS |
| US3905535A (en) * | 1973-09-13 | 1975-09-16 | Duo Fast Corp | Fastener driving tool |
-
1976
- 1976-11-11 DE DE19762651529 patent/DE2651529A1/en not_active Ceased
-
1977
- 1977-09-29 FI FI772867A patent/FI62969C/en not_active IP Right Cessation
- 1977-10-04 IT IT28267/77A patent/IT1088132B/en active
- 1977-10-06 GB GB41564/77A patent/GB1555901A/en not_active Expired
- 1977-10-06 AT AT0714077A patent/AT363875B/en active
- 1977-10-11 ZA ZA00776053A patent/ZA776053B/en unknown
- 1977-10-12 CH CH1248977A patent/CH624335A5/en not_active IP Right Cessation
- 1977-10-17 MX MX170972A patent/MX144290A/en unknown
- 1977-10-28 BE BE182181A patent/BE860270A/en not_active IP Right Cessation
- 1977-10-28 FR FR7732573A patent/FR2370555A1/en active Granted
- 1977-11-08 SE SE7712610A patent/SE7712610L/en not_active Application Discontinuation
- 1977-11-09 CA CA290,526A patent/CA1087939A/en not_active Expired
- 1977-11-09 AU AU30502/77A patent/AU3050277A/en active Pending
- 1977-11-09 NL NL7712339A patent/NL7712339A/en unknown
- 1977-11-10 JP JP13418177A patent/JPS5360772A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE2651529A1 (en) | 1978-05-18 |
| FI772867A (en) | 1978-05-12 |
| IT1088132B (en) | 1985-06-10 |
| ATA714077A (en) | 1981-01-15 |
| CH624335A5 (en) | 1981-07-31 |
| ZA776053B (en) | 1978-05-30 |
| AT363875B (en) | 1981-09-10 |
| SE7712610L (en) | 1978-05-12 |
| GB1555901A (en) | 1979-11-14 |
| NL7712339A (en) | 1978-05-16 |
| FI62969B (en) | 1982-12-31 |
| FR2370555A1 (en) | 1978-06-09 |
| MX144290A (en) | 1981-09-23 |
| FI62969C (en) | 1983-04-11 |
| FR2370555B1 (en) | 1980-08-08 |
| JPS5360772A (en) | 1978-05-31 |
| BE860270A (en) | 1978-02-15 |
| AU3050277A (en) | 1979-05-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |