U.S. patent application number 11/835496 was filed with the patent office on 2007-12-20 for method and apparatus for feeding fasteners to a processing device.
Invention is credited to Christian Reiter.
Application Number | 20070289354 11/835496 |
Document ID | / |
Family ID | 36091357 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289354 |
Kind Code |
A1 |
Reiter; Christian |
December 20, 2007 |
Method And Apparatus For Feeding Fasteners To A Processing
Device
Abstract
A method and apparatus for feeding fasteners with at least two
parallel boundary surfaces to a processing device includes lining
up the fasteners in the same orientation by a feeder. The fasteners
move through a conveying duct to a loading device arranged on a
processing device. Individual conveying steps are separated from
one another in time. At each conveying step a column of multiple
fasteners in the same orientation, with their parallel boundary
surfaces resting on one another, is conveyed by the feeder to the
loading device by introducing air into the conveying duct. The
loading device has, adjoining a magazine output end, a loading duct
extending perpendicular to a magazine longitudinal axis,
terminating in a processing device working duct. The loading duct
has a conveying mechanism which conveys individual fasteners
emerging from the magazine into the working duct one at a time.
Inventors: |
Reiter; Christian; (Giessen,
DE) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
36091357 |
Appl. No.: |
11/835496 |
Filed: |
August 8, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2006/050729 |
Feb 7, 2006 |
|
|
|
11835496 |
Aug 8, 2007 |
|
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Current U.S.
Class: |
72/424 |
Current CPC
Class: |
B23P 19/005 20130101;
B21J 15/32 20130101 |
Class at
Publication: |
072/424 |
International
Class: |
B21D 43/20 20060101
B21D043/20 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2005 |
DE |
10 2005 006 795.6 |
Claims
1. An apparatus for feeding fasteners having at least two parallel
boundary surfaces to a processing device, comprising: a feeder
operable to place a plurality of fasteners in a consistent
orientation; a conveying duct connected to the feeder; a magazine
connected to the conveying duct operable to receive the fasteners
from the conveying duct; a throttling port located at a magazine
end of the conveying duct; and a column defining a portion of the
fasteners formed for transport through the conveying duct, with
proximate ones of the boundary surfaces of the individual fasteners
resting one against the other, a back end of the column being
subjected to compressed fluid introduced into the conveying duct
defining a propulsive force operable to drive the column through
the conveying duct to the magazine, and a compressive force acting
on a front end of the column generated by resistance from a volume
of fluid in front of the column in the conveying duct being forced
through the throttling port, a combination of the propulsive force
and the compressive force acting to press the fasteners in the
column against one another to prevent the fasteners from assuming
an orientation that would impede their sliding through the
conveying duct.
2. The apparatus of claim 1, further comprising a loading device
operable to receive the fasteners and position the fasteners for
installation.
3. The apparatus of claim 2, further comprising a loading duct of
the loading device adjoining an output end of the magazine, the
loading duct extending perpendicular to a longitudinal axis of the
magazine and terminating in a working duct of the processing
device.
4. The apparatus of claim 3, further comprising a conveying
mechanism of the loading duct operable to convey individual ones of
the fasteners emerging from the magazine into the working duct of
the processing device one at a time.
5. The apparatus of claim 4, further comprising a piston operable
to drive the conveying mechanism.
6. The apparatus of claim 4, further comprising: a working duct
elastically expadable to receive individual ones of the fasteners
from the conveying mechanism; and a die oriented perpendicular to
the loading duct and adapted to force the individual ones of the
fasteners through the working duct into a workpiece.
7. The apparatus of claim 6, further comprising a detent pawl
operably biased by a biasing member to contact and temporarily hold
individual ones of the fasteners for contact by the die.
8. The apparatus of claim 1, wherein individual ones of the
plurality of fasteners each have an unfavorable aspect ratio
defining a diameter greater than an axial thickness.
9. An apparatus for feeding fasteners having at least two parallel
boundary surfaces to a processing device, comprising: a feeder
operable to place the fasteners in a consistent orientation; a
conveying duct connecting the feeder to a loading device arranged
on a processing device; a magazine associated with the loading
device accommodating a column of multiple fasteners delivered
through the conveying duct in the same orientation, the fasteners
having parallel boundary surfaces abutting one another; a loading
duct of the loading device adjoining an output end of the magazine,
the loading duct extending perpendicular to a longitudinal axis of
the magazine and terminating in a working duct of the processing
device; and a conveying mechanism of the loading duct operable to
convey individual ones of the fasteners emerging from the magazine
into the working duct of the processing device one at a time.
10. The apparatus of claim 9, wherein the loading device includes a
loading slide movable back and forth in the loading duct with the
aid of a pneumatically driven piston.
11. The apparatus of claim 10, comprising: a loading slide path of
motion extending over only a portion of a length of the loading
duct; and a pneumatic conveying mechanism activated by movement of
the loading slide operable to convey the fasteners on a section of
the loading duct not traversed by the loading slide.
12. The apparatus of claim 10, comprising: a pneumatic working
cylinder having a double-acting piston and a piston rod connected
to the loading slide; and a passage in communication with a working
chamber of the pneumatic working cylinder, the piston rod and the
loading slide traversed lengthwise by the passage when the loading
slide is in a position advanced toward the working duct.
13. The apparatus of claim 12, further comprising a valve needle
arranged in the working cylinder operable to control the pneumatic
conveying mechanism, wherein in a first position of the piston, the
valve needle is projected into the piston end of the passage, thus
closing it, and wherein in a second position of the piston, the
valve needle is withdrawn from the passage, causing the passage to
be connected to the working chamber.
14. The apparatus of claim 13, further comprising a sensor operable
to detect when the quantity of fasteners in the magazine falls
below a minimum level, the sensor further operable to trigger a
control process operable to convey a next column of fasteners to
the magazine.
15. The apparatus of claim 13, further comprising a counter
operable to detect when the quantity of fasteners in the magazine
falls below a minimum level, the sensor further operable to trigger
a control process operable to convey a next column of fasteners to
the magazine.
16. The apparatus of claim 13, further comprising: each of the
fasteners having a head section including a truncated cone shape;
and a top edge of the loading duct extending outward at an angle on
opposite sides of the loading duct operable to match the truncated
cone shape of the head section of the fasteners.
17. A method for feeding fasteners with at least two parallel
boundary surfaces to a processing device, the method comprising:
placing the fasteners in readiness, lined up in a same orientation
by a feeder; connecting a conveying duct between the feeder to a
loading device arranged on the processing device; moving the
fasteners in individual conveying steps which are separated from
one another in time through the conveying duct; grouping the
fasteners during individual ones of the individual conveying steps
as a column of multiple fasteners in the same orientation with the
parallel boundary surfaces resting on one another using pressurized
air introduced behind the column in the conveying duct; and
maintaining the individual fasteners of the column in contact with
each other by introducing a fluid backpressure at a forward end of
the column.
18. The method according to claim 17, comprising feeding the column
of fasteners to the loading device into a magazine of the loading
device.
19. The method according to claim 18, comprising: individually
removing the fasteners from the magazine by the loading device; and
feeding the fasteners to the processing device as a function of a
processing cycle.
20. The method according to claim 19, comprising conveying the
fasteners through the conveying duct to the magazine of the loading
device as a function of one of the processing cycle and a fill
level in the magazine.
21. The method according to claim 18, comprising accomplishing the
conveyance of the individual fasteners from the magazine to the
processing device partially mechanically and partially
pneumatically.
22. The method according to claim 17, comprising adjusting a
quantity of fasteners per column to adapt to an operating speed of
the processing device.
23. The method according to claim 17, comprising adjusting a
quantity of fasteners per a time interval between individual column
conveying cycles to adapt to an operating speed of the processing
device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/EP2006/050729, filed Feb. 7, 2006, which claims
the benefit of German Patent Application No. 10 2005 006 795.6,
filed Feb. 14, 2005. The disclosures of the above applications are
incorporated herein by reference.
FIELD
[0002] The invention concerns a method for feeding fasteners having
at least two parallel boundary surfaces to a processing device,
wherein the fasteners are placed in readiness, lined up in the same
orientation, by a feeder and are conveyed through a conveying duct
to a loading device arranged on the processing device. The
invention further concerns an apparatus for feeding fasteners to a
processing device having a feeder for placing the fasteners in
readiness in a uniform orientation, a loading device arranged on
the processing device, a conveying duct connecting the feeder to
the loading device, and a magazine associated with the loading
device for accommodating a plurality of fasteners lined up one
behind the other in the same orientation.
BACKGROUND
[0003] A method is known from EP 0,922,538 B1 wherein a fastener in
the form of a self-piercing rivet with a head and a shank recessed
from the head is fed by a feeder through a conveying duct to a
loading device arranged on the self-piercing riveting tool. The
conveying duct has a T-shaped cross-section that corresponds
essentially to the projected area of the self-piercing rivet. In
this context, the self-piercing rivets are fed to the conveying
duct with their longitudinal axes oriented perpendicular to the
direction of conveyance and are individually transported through
the conveying duct to the loading device by means of air. In the
loading device, the delivered self-piercing rivet is stopped, and
is held by means of movable positioning segments and an arresting
element in a suitable starting position for processing. This known
method and the devices for this purpose known from the
aforementioned document have been proven in use. However, the time
required for individual feeding of the fasteners has proven a
disadvantage for fast operating cycles and relatively long
application-specific conveying distances. Moreover, if the shape of
the rivet is unfavorable, increased wear on the walls of the
conveying duct can occur.
[0004] In a method known from EP 0,511,093 B1 for conditioning and
delivery of small, cylindrical parts, such as screws or rivets, the
small parts are arranged facing in the same direction, with the
shanks forward, in a column in a cylindrical supply tube. The
supply tube has at its top an opening for supplying parts and a
compressed air inlet, and at its bottom has an outlet associated
with a member for intermittent release of the parts. The
cylindrical tube is arranged in the shape of a ring in multiple
windings in the interior of a rigid container and forms a magazine
in which a large number of parts are stocked. The inner diameter of
the tube is larger than the greatest diameter of the parts by a
certain ratio so that an air stream which drives the parts toward
the outlet can flow along the tube toward the outlet past the parts
to the end of the outlet. This known method has the disadvantage
that it requires a relatively large installation space in the
vicinity of the processing device. Moreover, the energy
requirements for transporting the parts are relatively great, since
the entire column of many parts must be moved each time one part is
dispensed. Short-term changeover between parts of different lengths
is likewise not easily possible.
SUMMARY
[0005] The object of the invention is to specify a method of the
initially mentioned type that permits fast feed times, is
characterized by modest energy requirements, and contributes to low
wear of the conveying duct. It is a further object of the invention
to create an apparatus suitable for carrying out the method.
[0006] This object is attained in accordance with the invention by
the method and apparatus claims set forth herein. Advantageous
embodiments of the method and apparatus are specified in the
dependent claims referring back to each of these claims. In the
inventive method, the fasteners are conveyed in individual
conveying steps which are separated from one another in time,
wherein at each conveying step a column of multiple fasteners in
the same orientation, with their parallel boundary surfaces resting
on one another, is conveyed by the feeder to the loading device on
the processing device through the introduction of air into the
conveying duct.
[0007] The inventive method permits fast conveying times between
the feeder and the loading device, since multiple fasteners are
conveyed in each conveying step. The conveying speed can be varied
over a wide range by the choice of the time intervals between
conveying steps and the number of fasteners per conveying step. The
inventive method further permits comparatively low use of energy in
the form of compressed air, since the quantity of air and pressure
required for a conveying step encompassing multiple fasteners is
not significantly greater than for a conveying step for conveying a
single fastener, yet the number of conveying steps is many times
smaller than for individual conveying.
[0008] Surprisingly, it has additionally become apparent that the
inventive method contributes to a substantial reduction in wear of
the conveying duct and also to problem-free conveying of fasteners
with an unfavorable diameter-to-length ratio. This can be
attributed to the fact that the individual fasteners in the column
support one another with their parallel boundary surfaces, thus
stabilizing their position. Even when the fasteners are
self-piercing rivets, which have a sharp cutting edge at one end,
the fasteners can be conveyed using the inventive method with the
cutting edge first without this leading to appreciably greater wear
on the walls of the conveying duct.
[0009] Another proposal of the invention provides that the column
of fasteners fed to the loading device is accommodated in a
magazine of the loading device, and the fasteners are removed
individually from the magazine by the loading device and fed to the
processing device as a function of the processing cycle. The
fasteners are preferably conveyed through the conveying duct to the
magazine of the loading device as a function of the processing
cycle or the fill level in the magazine. A sensor or a counter
detects when the quantity of fasteners in the magazine falls below
a minimum level, thereby triggering a control process which brings
about the conveyance of a new column of fasteners to the
magazine.
[0010] An apparatus suitable for carrying out the method according
to the invention comprises a feeder that places fasteners in
readiness in a consistent orientation, a conveying duct that
connects the feeder to a loading device arranged on a processing
device, and a magazine associated with the loading device for
accommodating a column of multiple fasteners delivered through the
conveying duct in the same orientation, with their parallel
boundary surfaces resting on one another, wherein the loading
device has, adjoining an output end of the magazine, a loading duct
that extends perpendicular to the longitudinal axis of the magazine
and terminates in a working duct of the processing device, and
wherein the loading duct has associated with it a conveying
mechanism which conveys individual fasteners emerging from the
magazine into the working duct of the processing device one at a
time.
[0011] The inventive apparatus is characterized by a simple
construction and reliable operation. The loading device design with
a loading duct arranged at right angles to the longitudinal axis of
the magazine yields a compact construction of the loading device
and an advantageous arrangement of the magazine and conveying duct
with little interfering contour in the vicinity of the working area
of the processing device. Especially in the feeding of
self-piercing rivets to a riveting tool, favorable
three-dimensional shapes for the loading device with its magazine
result when the self-piercing rivets are fed to the magazine with
the cutting edge first. In the loading device, the self-piercing
rivets can then be transported perpendicular to their axis of
rotation from the magazine to the working duct of the riveting
tool, which ensures a reliably functioning feed of the individual
self-piercing rivets to the riveting tool.
[0012] According to another proposal of the invention, the
conveying mechanism of the loading device has a loading slide that
can be moved back and forth in the loading duct with the aid of a
pneumatically driven piston. According to another proposal of the
invention, the loading slide's path of motion extends over only
part of the length of the loading duct, and a pneumatic conveying
mechanism activated by the loading slide is provided to convey the
fasteners on the section of loading duct not traversed by the
loading slide. This embodiment permits a short stroke for the
loading slide, and thus a compact construction of the loading
device. Moreover, it prevents collisions between the loading slide
and tools of the processing device extending into the working
duct.
[0013] In an advantageous embodiment, a pneumatic working cylinder
with a double-acting piston whose piston rod is connected to the
loading slide is provided for moving the loading slide. In order to
form the pneumatic feed mechanism, the piston, the piston rod, and
the loading slide are traversed by a passage that communicates with
a working chamber of the pneumatic working cylinder when the
loading slide is in a position advanced toward the working duct. In
order to control the pneumatic conveying mechanism, a valve needle
is arranged in the working cylinder; in a first position of the
piston, the needle projects into the piston end of the passage,
thus closing it, and in a second position of the piston, the needle
withdraws from the passage, causing the passage to be connected to
the working chamber.
DRAWINGS
[0014] The invention is described below on the basis of an example
embodiment which is shown in the drawings.
[0015] FIG. 1 shows a riveting tool with a device for feeding
self-piercing rivets;
[0016] FIG. 2 shows a section through a conveying duct with a
column of self-piercing rivets resting upon one another; and
[0017] FIG. 3 shows a loading device for transporting individual
self-piercing rivets from a magazine into the working duct of a
riveting tool.
DETAILED DESCRIPTION
[0018] FIG. 1 shows a processing device shown for example as a
riveting tool 1 intended to process self-piercing rivets.
Self-piercing rivets are used to join components made of sheet
metal. They are pressed into the superposed metal sheets from one
side with great force by a die, with the metal sheets being
supported on an anvil that constitutes a support. The riveting tool
1 has a C-shaped yoke 2 for this purpose, which carries at one end
an anvil 3 and at the opposite end a housing 4 in which are
arranged a die that can be moved against the anvil 3 and a device
for driving the die. For feeding the self-piercing rivets, there is
located on the riveting tool 1 a loading device 5 with a magazine
6, which is supplied through a conveying duct 7 with self-piercing
rivets placed in readiness by a feeder 8. The conveying duct 7
consists of a resilient plastic tube, and in some applications must
bridge a gap of several meters between the feeder 8 and the
riveting tool 1.
[0019] FIG. 2 shows a longitudinal section through a portion of the
conveying duct 7. The wall 9 of the conveying duct 7 has an annular
cross-section and encloses a hollow space that, depending on the
course of the conveying duct 7, is cylindrical in part and in part
forms a segment of a torus. Located in the conveying duct 7 in FIG.
2 is a column of individual self-piercing rivets 10. The
self-piercing rivets 10 have a rotationally symmetric shape,
composed essentially of a cylindrical shank section 11 and a head
section 12 in the shape of a truncated cone. The axial ends of the
self-piercing rivet 10 are delimited by parallel circular areas 13,
14. The circular area 13 forms, together with the surface contour
of the shank section 11, a cutting edge 15. The greatest outer
diameter of the self-piercing rivet 10 is located at the head
section 12 and is somewhat smaller than the inside diameter of the
conveying duct 7 so that the self-piercing rivets 10 can slide
through the conveying duct 7 without jamming and without much
resistance.
[0020] As can be seen in FIG. 2, the self-piercing rivets 10 have
an unfavorable aspect ratio, since their diameter is greater than
their axial thickness. If the self-piercing rivets 10 were to fail
to maintain their coaxial position within the conveying duct 7
shown in FIG. 2 and turn about, they could jam in the conveying
duct 7 and prevent further transport to the loading device 5. This
is avoided by the invention in that a column is formed of a number
of self-piercing rivets 10 for transport through the conveying duct
7, with the circular areas 13, 14 of each of the individual
self-piercing rivets 10 resting one against the other. The back end
of the column is then subjected to compressed air introduced into
the conveying duct 7, which drives the column through the conveying
duct 7 to the magazine 6 designed in the manner of an end section
of the conveying duct 7. As a result of the propulsive force acting
on the back end of the column and the compressive force acting on
the front end of the column--generated by the resistance of the air
in front of the column in the conveying duct to being forced
through a throttling port at the magazine end of the conveying
duct--the self-piercing rivets 10 in the column are pressed against
one another and prevented from assuming an orientation that would
impede their sliding through the conveying duct. Consequently, the
self-piercing rivets 10 glide along the wall 9 of the conveying
duct 7, guided by the edge of their head sections 12, without their
cutting edges 15 being able to touch and damage the wall 9
appreciably.
[0021] From the conveying duct 7, the self-piercing rivets 10
arrive at the magazine 6 one column at a time. As is visible in
FIG. 3, the magazine 6 has an S-shaped magazine duct 16, which
joins the conveying duct 7 and has essentially the same diameter as
the conveying duct 7. The magazine 6 is rigidly connected to the
loading device 5 and the magazine duct 16 terminates at a right
angle in a loading duct 17 of the loading device 5. Unlike the
round cross-section of the magazine duct 16, the loading duct 17
has a rectangular cross-section, with a width corresponding to the
diameter of the shank section 11 of the self-piercing rivets 10.
The top edge 18 of the loading duct 17 is extended outward at an
angle on both sides to match the truncated cone shape of the head
section 12 of the self-piercing rivets 10 so that the head section
12 can be accommodated and held therein. The loading duct 17
extends from the termination of the magazine duct 16 to a working
duct 19, which branches off from the floor of the loading duct 17
at a right angle. Opposite the working duct 19, a bore 20
terminates in the loading duct 17; a die 21 that can move into the
working duct 19 is located in said bore 20. Immediately next to the
bore 20, a detent pawl 22 protrudes into the loading duct 17 from
above, which pawl is rotatably mounted and supported by a spring 23
in such a way that it can be pivoted out of the loading duct 17
against the force of the spring 23. The detent pawl 22 has a detent
surface 24 facing the bore 20, and on the opposite side has a ramp
surface 25 that is inclined to the longitudinal axis of the loading
duct and that recedes from the floor of the loading duct 17 when
viewed in the direction of the termination of the magazine duct
16.
[0022] Located next to the termination of the magazine duct 16 in
the loading duct 17 is a loading slide 26, which can move into the
loading duct 17. A pneumatic working cylinder 27 with a
double-acting piston 28 and a piston rod 29 is provided to move the
loading slide 26. The piston rod 29 is rigidly connected to the
loading slide 26. A passage 30 extends through the piston 28, the
piston rod 29 and the loading slide 26. A valve needle 31, which is
affixed to the cylinder block, projects into the piston end of the
passage 30, closing the passage 30. Connecting bores that are not
shown in the drawing connect working chambers 32, 33, which are
located on both sides of the piston 28, with a pneumatic valve
device for controlling the movement of the loading slide 26.
[0023] FIG. 3 shows the loading device 5 in an operating position
in which the loading slide 26 has returned to its starting position
after a loading process, wherein the loaded self-piercing rivet 10a
is still located in front of the termination of the working duct 19
and is held in this position by the side walls of the loading duct
17 and the detent pawl 22. In order to set the self-piercing rivet
10a, the die 21 is moved downward by operating the riveting tool 1,
in which process the side walls of the loading duct 17 move apart
to some degree so that the thicker head section of the
self-piercing rivet 10a can pass through the narrower region of the
loading duct 17. The die 21 then forces the self-piercing rivet 10a
through the loading duct 19, which elastically expands, thus
guiding the self-piercing rivet 10a in a frictional manner to the
workpieces resting on the anvil and pressing it into them. Then the
die 21 returns to the starting position shown so that the next
self-piercing rivet 10b can be loaded.
[0024] As the drawing shows, the self-piercing rivet 10b is already
located in the back end of the loading duct 17 in front of the
loading slide 26. The self-piercing rivet 10b has arrived in this
position as a result of gravity and compressed air introduced into
the magazine duct 16, which forces the column of self-piercing
rivets 10 toward the loading duct 17 even in the event of an
overhead arrangement of the riveting tool 1. In order to bring the
self-piercing rivet 10b into the working position between the die
21 and the working duct 19, compressed air is applied to the
working chamber 32 of the working cylinder 27 and the working
chamber 33 is connected to the atmosphere. This causes the piston
28 to move the loading slide 26 into the loading duct 17, pushing
the self-piercing rivet 10 b ahead of it and simultaneously closing
the outlet of the magazine duct 16. Before the piston 28 reaches
its end position on the floor of the working chamber 33, the valve
needle 31 emerges from the passage 30, with the result that the
compressed air supplied to the working chamber 32 flows through the
passage 30 and exits at the end face of the loading slide 26. The
emerging stream of air strikes the self-piercing rivet 10b and
pushes it under the detent pawl 22, which deflects upward, and into
the end position under the die 21, where it is held in place by the
detent surface 24 of the detent pawl 22 which has sprung back to
its initial position. As soon as the piston 28, and with it the
loading slide 26, have reached their advanced end position, the
compressed air supply to the piston 28 is reversed, moving the
piston and the loading slide 26 back into the initial position as a
result of the compressed air introduced into the chamber 33. Once
the loading slide 26 has exposed the outlet of the magazine duct
16, the column of self-piercing rivets 10 moves in the direction of
the loading duct 17 until the foremost self-piercing rivet reaches
the position of the self-piercing rivet 10 b, where its head
section is supported against the upper edge of the loading
duct.
[0025] Reliable conveyance of the self-piercing rivets into the
working duct of the riveting tool is achieved through the design
and method of operation of the loading device 5 described above.
Rotation of the rivets is not necessary. The combination of
mechanical conveyance with the aid of the loading slide and the
subsequent pneumatic conveyance of the self-piercing rivet into its
working position permits a compact design of the loading device.
The interaction of mechanical and pneumatic conveyance is
controlled in a simple manner as a function of travel, and thus
requires no additional control. The described design of the
apparatus additionally has the advantage that self-piercing rivets
of different lengths can be fed without the need to make changes in
the device. The conveyance of columns of rivets into the magazine
arranged on the loading device permits high working speed for the
riveting tool and makes for low consumption of compressed air.
* * * * *