U.S. patent number 3,866,692 [Application Number 05/328,916] was granted by the patent office on 1975-02-18 for power tools.
This patent grant is currently assigned to Rockwell International Corporation. Invention is credited to Charles R. Stelljes.
United States Patent |
3,866,692 |
Stelljes |
February 18, 1975 |
POWER TOOLS
Abstract
Power driven devices in which a tool is axially impacted via a
driver mounted in a reciprocably driven piston. The tool can be
intermittently rotated or not, as desired.
Inventors: |
Stelljes; Charles R.
(Fayetteville, NY) |
Assignee: |
Rockwell International
Corporation (Pittsburgh, PA)
|
Family
ID: |
23283022 |
Appl.
No.: |
05/328,916 |
Filed: |
February 2, 1973 |
Current U.S.
Class: |
173/48; 173/110;
173/133; 173/118 |
Current CPC
Class: |
B25D
16/006 (20130101); B25F 5/001 (20130101); E21B
6/06 (20130101); B23B 45/008 (20130101); F16D
7/044 (20130101) |
Current International
Class: |
B25D
16/00 (20060101); B23B 45/00 (20060101); E21B
6/00 (20060101); E21B 6/06 (20060101); F16D
7/04 (20060101); F16D 7/00 (20060101); B25d
011/12 () |
Field of
Search: |
;173/47,48,104,109,110,111,116,117 ;64/29 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Purser; Ernest R.
Assistant Examiner: Pate, III; William F.
Claims
1. A power driven device, comprising: a casing; a tool holder
rotatably mounted in said casing; means which can be cycled through
impacting and return strokes for imparting axial impacts to a tool
mounted in said tool holder; means including a driving member and a
driven member having means providing a drive connection
therebetween for so connecting said impact imparting mechanism to
said tool holder that said mechanism rotatably indexes said tool
holder and the tool mounted therein during one of the strokes in
each cycle thereof but does not effect rotation of the tool holder
in the other of said strokes; and means selectively operable to
effect a relative displacement between said driving and driven
members which will interrupt the drive connection therebetween so
that said tool can be axially impacted without rotating it, said
driven member being connected to said tool holder for rotation
therewith and being axially fixed relative to said casing, said
tool holder and said driving member being axially movable relative
to driven member, the means for connecting the impact imparting
mechanism to said tool holder including means biasing said driving
member toward said driven member to complete the drive connection
therebetween, and the means for interrupting said drive connection
being arranged to move said driving member away from said
2. The power driven device of claim 1, wherein the means for
interrupting the drive connection between the driving and driven
members by moving said driving member away from said driven member
includes a member surrounding said driving member and having an
inwardly directed flange engageable with said driving member on the
side thereof nearest the driven member and means for displacing
said flanged member relative to said driven member comprising a
member journalled in said casing means for rotation about an axis
normal to the path of movement of the flanged member and accessible
from the exterior of the casing and an eccentric extending from the
inward end of said pin and engaged with said flanged member,
whereby said flanged member will be displaced as the member
journalled in said casing is
3. The power driven device of claim 2, wherein the flanged member
is cylindrical and surrounds the driving member, wherein there are
rotatably journalled members as aforesaid in axial alignment in
opposite sides of said casing, and wherein the means for moving the
driving member away from the driven member also includes means for
concomitantly rotating said
4. The power driven member of claim 1, wherein the means for moving
said driving member away from said driven member includes a fixed
cam means, rotatable cam means between and engageable with said
fixed cam means and that side of the driving member nearest the
driven member, there being co-operating portions of said fixed and
movable cam means so configured that said movable cam will be
displaced relative to said fixed cam and move the driving member
away from the driven member as said rotatable cam
5. The power driven member of claim 4, wherein the means for
rotating said actuator comprises a member journalled in the casing
for rotation about an axis normal to the path of movement of the
driving member and accessible from the exterior of the casing and
an inwardly extending eccentric engageable with said rotatably
journalled member and said rotatable cam
6. The power driven device of claim 1, wherein the means for drive
connecting the impact imparting mechanism to the tool holder
includes a frictional drive connection providing means capable of
transmitting only forces up to a selected maximum magnitude
operatively connected between said impact imparting mechanism and
the driving member, whereby the drive connection between the impact
imparting mechanism and the tool holder is effectively interrupted
while there is a rotation restraining force on said tool holder
which exceeds the magnitude of the force which said
7. The power driven device of claim 1, wherein the means for drive
connecting the impact imparting mechanism to the tool holder
includes a ratchet means having said driving member as an input and
said driven member as an output and means for rotating said driving
member back and forth as said impact imparting mechanism moves
through its impacting and return strokes, there being cooperating
first and second means on said driving and driven members
engageable when said driving member is rotated in one direction
only to rotatably advance said driven member and said
8. A power driven device, comprising: a casing; a tool holder
rotatably mounted in said casing which can be cycled through
impacting and return strokes to impart axial impacts to a tool
mounted in said tool holder; a mechanism for rotatably indexing
said tool during only a selected part of the cycle of operation of
the impact imparting mechanism which includes torque transmitting
driving and driven members and means for disengaging said members
when axial impact only is wanted and engaging them when both
rotation and impacting is wanted; and a rotation transmitting,
torque release means in series with the mechanism for rotatably
indexing the tool for keeping the torque imposed on said tool from
exceeding a selected value.
Description
The present invention relates to power driven devices and, more
particularly, to power driven devices for drilling holes in or
otherwise working concrete, masonry, and the like by axially
impacting a tool against the workpiece, either with or without
intermittent rotation of the tool, depending upon the task and the
material involved.
One primary object of the present invention resides in the
provision of novel, improved power driven devices of the type just
described. Such devices are commonly referred to as power hammers
or power driven hammers; and this terminology will, accordingly, be
employed herein with the understanding that it is intended to be
only descriptive and not limiting.
In power hammers as heretofore proposed, tools with one shank
configuration are employed if rotation of the tool is wanted; and
tools with a different shank configuration are used if axial impact
only is desired. This has the disadvantages of requiring two sets
of tools, of necessitating a change of tools to shift from one
operating mode to the other, etc.
I have now invented novel power driven hammers which are free of
the above-enumerated and other disadvantages. In brief, these
hammers include a mechanism of the character described in U.S. Pat.
No. 3,650,336 issued Mar. 21, 1972, to Heinrich P. Koehler for
POWER DRIVEN DEVICE for impacting a tool and a ratchet mechanism of
the character therein disclosed for imparting intermittent rotation
to the tool. In the devices described and illustrated in this
patent, the motor of the device is connected through a
rotary-to-reciprocating motion converting mechanism to the impact
producing mechanism, which consists of a reciprocable piston in
which a free-floating driver is slidably mounted.
The driver is dimensioned to strike a closed type tool holder to
impart axial impacts to a tool in the holder. Controlled flow of
air into and out of the piston on opposite sides of the driver
produces positive forces for propelling the driver through its
working and return strokes and provides cushions which prevent the
driver from striking the ends of the piston as it moves
back-and-forth therein.
During each cycle of the impact imparting mechanism, the tool
socket and the tool mounted therein are rotatably advanced through
an angle of preselected magnitude by a novel motion transmitting
mechanism driven by the piston. This mechanism is also torque
responsive and interrupts the rotary drive connection between the
piston and tool socket if the tool binds or sticks.
The rotary motion producing mechanism includes a drive member which
is connected to the reciprocable piston by helical splines so that
the drive member rotates back-and-forth as the piston reciprocates.
This motion of the drive member is converted to intermittent
unidirectional rotary motion by a ratchet arrangement which has an
input rotatable with the drive member just described. The output
member of the ratchet arrangement and, consequently, the tool
holder and the tool mounted therein rotate or advance only as the
drive member rotates in one of its two opposite directions.
In addition to the components just described, my power driven
hammers include a novel selector mechanism with an actuator
accessible from the exterior of the casing for moving the input and
output members of the ratchet mechanism out of engagement when
axial impacting of the tool without rotation is wanted. Thus, by
simply moving the actuator from one to the other of two positions,
axial hammering alone or axial hammering plus intermittent rotary
advance of the tool can be provided.
The novel arrangement just described increases to a maximum the
speed and ease with which power driven hammers can be shifted
between the two modes of operation. And it also eliminates the need
for two sets of tools with different shank configurations to
produce the two modes of operation. At the same time the selector
mechanism I employ is simple and rugged and, therefore, has a long
service life ant is relatively inexpensive to incorporate in a
power hammer and to maintain.
One selector mechanism for a power driven impact device which
affords a choice between axial impacting alone and axial impacting
plus rotation has heretofore been disclosed in U.S. Pat. No.
3,334,694, issued Aug. 8, 1972, to J. L. Schnettler for ROTARY
HAMMER. However, the Schnettler mechanism is quite different from
that I have invented and could not be used in power driven hammers
which employ impacting mechanisms and drives for producing
intermittent rotary advance of a tool of the character described
above.
Aside from those just discussed, the novel power hammers of the
present invention have the advantages of being compact and
relatively light and of having good balance due to the manner in
which the motor is positioned with respect to the
rotary-to-reciprocatory motion convering mechanism. They are also
rugged, providing a long service life, and uncomplicated, making
them comparatively inexpensive to manufacture and maintain.
Furthermore, the novel hammers of the present invention are highly
effective in drilling and like operations because of the
intermittent rotation imparted to the tool in conjunction with
axial impacts.
Further, the novel closed type tool holder employed in the hammers
of the present invention has been found effective in preventing
foreign matter from penetrating to the interior of the hammer
casing. This also contributes to proper operation of the hammer and
to long service life.
One primary object of the present invention was identified
above.
Another primary object of the present invention resides in the
provision of power hammers with novel, improved mechanisms for
providing a choice between axial hammering alone or axial hammering
plus intermittent rotation of the tool.
Other important, but more specific objects of the present invention
reside in the provision of novel, improved power driven
hammers:
1. with a selector mechanism for shifting between different modes
of operation which eliminates the need for employing tools with
different shank configurations in these modes.
2. with a selector mechanism for shifting between different modes
of operation which includes an actuator accessible from the
exterior of the tool.
3. with a selector mechanism for shifting between different modes
of operation which is simple and rugged and, therefore, relatively
inexpensive to manufacture and maintain and which can be added to
existing designs without major modifications in them.
4. which are particularly effective for drilling holes in concrete,
masonry, rock, and the like.
5. which are compact and relatively light and well balanced.
6. which, apart from the selector mechanism, are rugged and
uncomplicated and, therefore, have a long service life and are
relatively inexpensive to manufacture and service.
7. which are versatile.
8. which are constructed to minimize the penetration of foreign
matter to the interior of the hammer.
9. which have various combinations of the desirable attributes just
described.
Other objects and features and additional advantages of the
invention will become apparent from the appended claims and as the
ensuing detailed description and discussion proceeds in conjunction
with the accompanying drawing, in which:
FIG. 1 is a side view of a power driven hammer constructed in
accord with the principles of the present invention and equipped
with a selector mechanism in accord with that invention for
providing a choice between axial hammering and intermittent rotary
advance of a tool and axial hammering alone;
FIG. 2 is a longitudinal section through the front end of the power
driven hammer of FIG. 1;
FIG. 3a is a fragmentary side view of the mechanism employed in the
hammer of FIG. 1 to produce axial hammering and intermittent rotary
advance of the tool;
FIG. 3b is a view similar to FIG. 3a but with the selector
mechanism operated to interrupt the rotary advance of the tool so
that it will only be axially impacted;
FIG. 4 is a pictorial view of a cup-shaped actuator employed in the
selector mechanism;
FIG. 5 is a section through the tool taken substantially along line
5--5 of FIG. 2;
FIG. 6 is a view similar to FIG. 2 of a hammer similar to that
shown in FIG. 1, but equipped with an alternate form of selector
mechanism;
FIG. 7 is a partially sectioned side view of the selector mechanism
employed in the hammer of FIG. 6; and
FIG. 8 is a pictorial view of two cam members which are components
of the selector mechanism.
Referring now to the drawing, FIGS. 1 and 2 depict a power driven
hammer 18 constructed in accord with the principles of the present
invention. The major components of hammer 18 include a casing 20
housing a motor drive-connected through a rotary-to-reciprocable
motion converting mechanism (neither shown) to the piston 26 of an
impact imparting mechanism 28 which also includes a free-floating
driver 20 slidably mounted in the piston. Driver 30 is adapted to
periodically strike and impart an impact to an axially movable tool
holder 32 mounted in the forward end of casing 20 and thence to a
tool 33 socketed in the tool holder and retained in place by a
conventional spring type retainer 34. The tool may also be
intermittently rotated or advanced during each working stroke by
the piston, which is drive-connected to tool holder 32 through a
reciprocable to intermittent, undirectional, rotary motion
converting drive mechanism 36. Drive mechanism 36 is also designed
to serve an overload function; i.e., to interrupt the drive
connection between piston 26 and tool holder 32 if the rotation
resisting torque exerted by the tool on the tool holder rises above
a predetermined magnitude.
Hammer 18 also includes a novel selector mechanism 37 having an
actuator 38 accessible from the exterior of casing 20. With the
actuator in one of two positions drive mechanism 36 is operable to
incrementally advance the tool 33 in tool holder 32. With the
actuator in its other position, continuity in the drive mechanism
is interrupted; and tool 33 is, therefore, axially impacted but not
rotated.
Hammer 18 also has a pistol grip 39 supporting a switch 40 for
controlling the operation of its motor. The details of these
components are not part of the present invention and will,
accordingly, not be described herein.
Referring now specifically to FIG. 2, piston 26 is supported for
reciprocable, rectilinear movement in casing 20 by a piston guide
which has not been shown because it is not part of the present
invention and because it is described in detail in U.S. Pat. No.
3,650,336.
Free-floating driver 30, the other component of the axial impact
producing mechanism, has a head 42 dimensioned for a sliding fit in
the main body portion 44 of piston 26 and a smaller diameter stem
46 dimensioned for a sliding fit in the necked down forward portion
48 of the piston. Driver 30 is extendible from one end of piston 26
into impacting engagement with tool holder 32 as piston 26 moves
forwardly (i.e., toward the nose end of the hammer) and displaced
toward the rearward end of the piston during the return stroke of
the latter by the controlled ingress of air into piston 26 on
opposite sides of driver head 42 and the controlled egress of air
therefrom.
The tool holder 32 against which driver 30 impacts includes a
cylindrical main body portion 50 in which a tool receiving socket
52 is formed and a closed rear wall 54, which prevents foreign
matter from penetrating through the tool socket to the interior of
casing 20.
Tool holder 32 is mounted for rectilinear movement in tool casing
20 with a flange 56 at its nose slidingly engaging the interior of
the casing section. An O-ring 58 disposed in a recess 60 formed in
the tool holder nose portion prevents foreign matter from
penetrating to the interior of the tool casing around the tool
holder.
A ring 62 of resilient material is preferably disposed in the
forward end of casing 20 in spaced relation to tool holder 32. This
ring keeps tool holder 32 from striking and damaging the casing
with motor of hammer 18 running and the hammer idling or with no
tool in the tool holder.
The main body portion 50 of the tool holder extends into a bore 64
through the output or driven member 66 of a ratchet type,
intermittent rotary motion producing mechanism 68 incorporated in
motion converting drive mechanism 36. Output member 66 is rotatably
mounted in casing 20, but is fixed against axial movement by an
annular ledge 70 in the casing and a retainer 72 fitted therein.
External splines 76 on the main body portion 50 of tool holder 32
and cooperating internal splines 78 in the bore 64 of driven member
66 connect the tool holder to ratchet output member 66 for rotation
therewith.
The motion converting mechanism 36 also includes a motion
converting component or drive member 80 having an internal bore 82
through which the forward end portion 48 of piston 26 extends (see
FIGS. 2 and 5). Member 80 is rotatably and axially movable in a
bore 84 through an annular boss 86 in casing 20.
Helical external splines 88 are formed on the forward end portion
48 of piston 26; and cooperating, internal, helical splines 90 are
formed in the bore 82 of driven member 80. Accordingly, as piston
26 is reciprocated, it effects an oscillatory or to-and-fro rocking
movement of drive member 80 through an angle determined by the
configuration of cooperating splines 88 and 90.
The cylindrical input member 92 of a friction clutch 94 is
journalled on and fixed to member 80 for rotation therewith. The
output member 96 of clutch 94 is similarly journalled on member 80,
but is free to rotate relative to this member. Clutch output member
96 is also the input or drive member of ratchet mechanism 68.
Clutch members 92 and 96 are frictionally drive connected by
Belleville washers 98 and 100 journalled on motion converting drive
component 80 between the clutch elements and frictionally engaging
the forward face 102 of input member 92 and the rear face 104 of
output member 96. The Belleville washers allow friction clutch
output member 96 to slip relative to input member 92 when the tool
sticks or is otherwise subjected to a restraining torque of more
than a predetermined magnitude.
Ratchet teeth 106 are formed on the forward face 108 of clutch
output/ratchet input member 96, and cooperating ratchet teeth 110
are formed on the rear face 112 of ratchet output member 66. Clutch
output member 96 and ratchet output member 66 are biased into
driving relationship by a compression spring 114 having one end
which abuts friction clutch input member 92. The other end of this
spring engages an annular ledge 116 formed in casing 20.
With teeth 106 and 110 engaged, clutch member 96 drives ratchet
output member 66 when motion converting component 80 is oscillated
or rotated by piston 26 in one direction. However, when
output-input member 96 is rotated in the opposite direction by
component 80, teeth 106 slide over the teeth 110; and no rotary
motion is imparted to output member 66.
The rotary advance is transmitted to tool holder 32 as it is
splined to ratchet output member 66. The incremental advance is in
turn transmitted to the tool 33 mounted in the tool socket by
employing matching configurations in the tool socket and on the
shank of tool 33 to connect them for concomitant rotary
movement.
When only hammering axial of tool 33 is wanted, the actuator 38 of
selector 37 is shifted to the second of its two positions. This
moves clutch output-ratchet input member 96 toward the rear of
hammer 18 against the bias exerted by spring 114 and holds it
there. Accordingly, although input member 96 continues to be rocked
or oscillated by motion converting member 80, this rotary motion is
not transmitted to tool holder 32 or the tool 33 mounted therein
although the tool holder and tool continue to be impacted by driver
30 as piston 26 moves back-and-forth through its impacting and
return strokes.
More specifically, the selector mechanism 37 of hammer 18 includes
a cup-shaped member 134 (See FIG. 4) surrounding ratchet mechanism
input member 96. An inwardly extending, radial flange 136 on member
134 engages the forward face 108 of input member 96 beyond the
teeth 106 formed thereon as shown in FIG. 2.
Member 134 is moved toward the rear of hammer 18 to disengage teeth
106 from the teeth 110 on ratchet mechanism output member 66 by
rotating actuator 38 (which is a U-shaped bail) from the position
shown in FIG. 3A to that shown in FIG. 3B.
Legs 140 of the bail extend through apertures 144 in two shafts or
stems 146 (see FIGS. 2 and 5). Stems 146 are mounted in axially
aligned apertures 148 on opposite sides of casing 20 for rotation
about an axis extending at right angles to the path along which
ratchet input member 96 can move relative to output member 66.
Fixed to or integral with and extending inwardly from stems 146 are
eccentrics 150, which extend through slots 152 in member 134.
Therefore, as bail 38 is displaced to the FIG. 3B position, the
rotation of stems 146 displaces member 134 toward the rear of
hammer 18 against the force exerted by compression spring 114,
disengaging ratchet input member 96 from output member 66. For the
reasons discussed above, the tool holder 32 of hammer 18 and the
tool 33 mounted in it then continue to be subjected to axial
impacting, but do not rotate.
When intermittent rotation of tool 33 is again wanted, bail 38 is
rotated back to the FIG. 3A position. As it is displaced, the
cup-shaped member 134 moves forwardly; and ratchet teeth 106 and
110 re-engage so that the ratchet output member 66 and tool holder
32 will be rotatably advanced as piston 26 reciprocates.
A second form of selector mechanism 158 is employed in the hammer
160 shown in fragmentary form in FIG. 5. Because hammer 160 is the
same as hammer 18 except for the selector mechanism, the former
will be described only as necessary to make clear the construction
and operation of the selector mechanism; and those components of
hammer 160 common to it and hammer 18 will be identified by the
same reference characters.
Selector mechanism 158 includes a ringlike fixed cam 162
surrounding ratchet output member 66. Adjacent fixed cam 162 is a
second, also ringlike cam 164, which is both slidable and rotatable
in casing 20. The rear face 166 of the movable cam is dimensioned
to engage the forward face 108 of ratchet mechanism input member 96
beyond teeth 106.
Cams 164 and 162 have cam faces 168 and 170 so configured that,
when cam 164 is rotated relative to the fixed cam, it will be
displaced toward the rear of hammer 160 against the force exerted
by compression spring 114. This displaces ratchet input member 96
to the rear, disengaging the teeth 106 on the latter from the teeth
110 on ratchet mechanism output member 66 as in the embodiment of
the invention described previously to keep rotary motion from being
imparted to the tool holder 32 of hammer 160 or to the tool mounted
in it.
Cam 164 is rotated to disengage the ratchet mechanism input and
output members 96 and 66 in the manner just described by turning a
knob 174 located exteriorly of casing 20. Fixed to or integral with
knob 174 is a stem or shaft 176 mounted in casing 20 for rotation
about an axis extending at right angles to the path along which
ratchet input member 96 moves as it is disengaged from and engaged
with output member 66. Stem 176 is retained in place by a retainer
ring 178 fitted in the stem and by a spring 180 between retaining
ring 178 and a ledge 182 in casing 20.
Also fixed to or integral with stem 176 is an eccentric 184 which
extends into a longitudinal slot 186 formed in the periphery of
rotatable cam 164.
With knob 174 in the position shown in FIG. 6, pin 188 is biased by
spring 180 into a groove 190 in an arcuate boss 192 formed in
casing 20, restraining knob 174 against rotation. Ratchet members
96 and 66 are engaged, and the tool (not shown) in tool holder 32
is rotatably advanced as the piston 26 of the impact imparting
mechanism reciprocates.
When axial impact only is wanted, knob 174 is pulled away from
casing 20, lifting pin 188 out of groove 190 and freeing knob 174
for rotation relative to the casing. The knob is then rotated until
pin 188 is aligned with a second groove 194 in boss 192 and seated
in the groove by spring 180 to again restrain the knob against
rotation.
As knob 174 is rotated, eccentric 184 rotates movable cam 164,
causing one of the cam faces 168 formed on it to ride up the
associated cam face 170 on fixed cam 162. This displaces cam member
164 toward the rear of the tool.
For example, if knob 174 is rotated in the direction shown by arrow
196 in FIG. 7, movable cam 164 will be rotated in the direction
indicated by arrow 198, moving the cam rearwardly as shown by arrow
200.
As cam member 164 engages the forward face of ratchet member 96,
the ratchet input member also moves toward the rear of the tool.
This separates ratchet teeth 106 from ratchet teeth 110, and the
tool in tool holder 32 will be axially impacted but will not be
rotated.
When rotary advance is again wanted, the process just described is
reversed. Knob 174 is pulled away from housing 20 freeing it for
rotation and then turned until pin 188 drops into groove 190 under
the biasing influence of spring 180. This allows ratchet spring 114
to bias movable cam 164 forwardly to the position shown in FIG. 6,
re-engaging ratchet teeth 106 and 110. This completes the
continuity in drive mechanism 36 and the intermittent rotary
advance of tool holder 32 and the tool socketed in it is
resumed.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
present embodiments are therefore to be considered in all respects
as illustrative and not restrictive, the scope of the invention
being indicated by the appended claims rather than by the foregoing
description, and all changes which come within the meaning and
range of equivalency of the claims are therefore intended to be
embraced therein.
* * * * *