U.S. patent number 3,777,825 [Application Number 05/269,774] was granted by the patent office on 1973-12-11 for hammer drilling machine.
This patent grant is currently assigned to Firma Impex-Essen Vertrieb von Werkzaugen GmbH. Invention is credited to Reinhold Gullich.
United States Patent |
3,777,825 |
Gullich |
December 11, 1973 |
HAMMER DRILLING MACHINE
Abstract
A hammer drilling machine selectively switchable between pure
drilling and hammer drilling modes operates with reduced frictional
heat due to the construction of the percussion mechanism. During
hammer drilling there is no relative rotation between the plunger
and the drilling spindle. The percussion mechanism includes two
co-operable cam members, both of which are stationary when the
machine is idling, and one of which is connected to the plunger and
is set into rotation with the machine in the hammer drilling mode
by axial displacement of the drilling spindle.
Inventors: |
Gullich; Reinhold (Ansbach,
DT) |
Assignee: |
Firma Impex-Essen Vertrieb von
Werkzaugen GmbH (Ansbach, DT)
|
Family
ID: |
5818723 |
Appl.
No.: |
05/269,774 |
Filed: |
July 7, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Sep 4, 1971 [DT] |
|
|
P 21 44 449.5 |
|
Current U.S.
Class: |
173/13; 173/109;
173/48 |
Current CPC
Class: |
B25D
16/00 (20130101); B25D 16/006 (20130101); B25D
2211/064 (20130101) |
Current International
Class: |
B25D
16/00 (20060101); E21c 001/12 () |
Field of
Search: |
;173/13,48 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Purser; Ernest R.
Claims
I claim:
1. A hammer drilling machine comprising gearing which can be
switched selectively between drilling and hammer drilling modes of
operation, a drilling spindle which is mounted for limited axial
displacement, and a percussion mechanism arranged symmetrically
about the drilling spindle, said percussion mechanism comprising a
plunger which is subject to the action of spring means and is
axially displaceable relative to the drilling spindle, and two
co-operable cam members, one of which is connected to the plunger,
wherein both cam members remain stationary when the machine is
idling and wherein said cam member connected to the plunger is
arranged to be set into rotation with the machine in the hammer
drilling mode by axial displacement of the drilling spindle.
2. A hammer drilling machine according to claim 1, in which the
other of the cam members is permanently fixed in position and is
machined into a lock nut connected into a housing for the
percussion mechanism.
3. A hammer drilling machine according to claim 1, in which said
cam member connected to the plunger is coupled to the drilling
spindle with the machine in the hammer drilling mode through the
plunger.
4. A hammer drilling machine according to claim 3, in which said
one cam member is machined directly from the plunger.
5. A hammer drilling machine according to claim 3, in which the
plunger is arranged to be axially displaceable but non-rotatable on
a coupling sleeve which is mounted for rotation and limited axial
movement on the drilling spindle, said sleeve having at its one end
coupling means for engagement with coupling means on the drilling
spindle and supporting at its other end said spring means which is
arranged to be stressed by axial movement of the plunger.
6. A hammer drilling machine according to claim 5, in which the
coupling sleeve is provided at its said other end with an annular
supporting member for said spring means.
7. A hammer drilling machine according to claim 5, in which the
coupling sleeve is supported with the machine in the hammer
drilling mode by an inner ring of a driving-end drilling spindle
roller bearing against the force of said spring means.
8. A hammer drilling machine according to claim 5, in which a
striker plate transmitting the hammer blows of the plunger to the
drilling spindle carries said coupling means on the drilling
spindle which is engageable with said coupling means on the
sleeve.
9. A hammer drilling machine according to claim 1, in which the end
of the drilling spindle to which the rotary driving force is
imparted carries an axially displaceable driving gear wheel.
10. A hammer drilling machine according to claim 9, in which the
driving gear wheel has an inclined tooth periphery urging it in the
feed direction.
Description
BACKGROUND TO THE INVENTION
This invention relates to a hammer drilling machine comprising
gearing which can be switched between drilling and hammer drilling
modes of operation, a drilling spindle which is mounted for limited
axial displacement, and a percussion mechanism arranged
symmetrically about the drilling spindle, the percussion mechanism
comprising a plunger which is subject to the action of spring means
and is axially displaceable relative to the drilling spindle, and
two co-operable cam members, one of which is connected to the
plunger.
DESCRIPTION OF THE PRIOR ART
In the building and construction industries, for working on rock or
stone, there are used both heavy jack hammers and drill hammers,
generally operated by compressed air, and also lighter and smaller
hammer drilling machines. These latter are designed for electrical
operation and are equipped with comparatively weak mechanical
percussion mechanisms, which, as also with percussion drilling
machines, do not begin automatically to hammer in the idling state,
i.e., when the machine is not set against the stone, but only after
drilling begins when pressure is exerted on the machine in the
direction of drilling. The percussion mechanism of these hammer
drilling machines operates substantially without recoil until the
feed or the pressure of the machine against the stone in the
direction of drilling ends.
In one known machine of this kind, a plunger is axially
oscillatable directly on an axially movable drilling spindle under
the effect of the force of a spring, in such a way that a cam ring
or toothed disc rigidly screwed to the plunger co-operates with a
cam ring or toothed disc of the drilling spindle. The latter is
displaced on setting the machine against the stone or on feeding
axially in the direction of the interior of the gear housing, so
that coupling teeth on the plunger are brought into engagement with
coupling teeth fixedly arranged in the housing and the plunger is
secured against rotation. The toothed discs and springs thereby
allow the plunger to hammer upon the drilling spindle with a
predetermined rhythm. When the machine is idling, the spring acts
so that the toothed discs perform no rotation relative to one
another and the plunger is then rotated together with the drilling
spindle. This co-rotation of the plunger and the toothed discs
coupling it to the drilling spindle also takes place during pure
drilling with the drill, in which mode the axial movement of the
drilling spindle is blocked. The primary disadvantage of this known
machine is that in the hammer drilling mode which loads the machine
to the greatest degree, additional frictional heat is produced by
the drilling spindle rotating in the plunger and behaving as a
guide for it at the same time.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hammer
drilling machine of the kind first mentioned above in which the
frictional heat losses are limited to a minimum and in which also
the electric power input requirements can be kept small.
In accordance with the invention there is provided a hammer
drilling machine comprising gearing which can be switched
selectively between drilling and hammer drilling modes of
operation, a drilling spindle which is mounted for limited axial
displacement, and a percussion mechanism arranged symmetrically
about the drilling spindle, said percussion mechanism comprising a
plunger which is subject to the action of spring means and is
axially displaceable relative to the drilling spindle, and two
co-operable cam members, one of which is connected to the plunger,
wherein both cam members remain stationary when the machine is
idling and wherein said cam member connected to the plunger is
arranged to be set into rotation with the machine in the hammer
drilling mode by axial displacement of the drilling spindle. For
the invention, it is important that both cam members remain still
on idling and that when operating in the hammer drilling mode only
the cam member connected to the plunger is rotated upon setting the
machine against the stone or on advancing the machine. Thus, during
hammer drilling, there is no relative rotation between the plunger
and the drilling spindle and thus no corresponding frictional
losses. The power capacity of the driving motor can also be
reduced, since when idling, when operating in the hammer drilling
mode, and during pure rotational drilling, the plunger does not
need to be enclosed or to be correspondingly accelerated.
In a preferred embodiment of the invention, said cam member
connected to the plunger is coupled to the drilling spindle with
the machine in the hammer drilling mode through the plunger. The
other cam member co-operating with this cam member can therefore be
fixedly arranged so that the construction of the percussion gearing
is very simple.
Preferably, the plunger is arranged to be axially displaceable but
non-rotatable on a coupling sleeve which is mounted for rotation
and limited axial movement on the drilling spindle, said sleeve
having at its one end coupling means for engagement with coupling
means on the drilling spindle and supporting at its other end said
spring means which is arranged to be stressed by axial movement of
the plunger.
The coupling sleeve thus carries the oscillatable plunger, so that
the sliding friction originating from the oscillatory movement is
transferred to the coupling sleeve and does not have an effect on
the upper surface of the drilling spindle, as is the case with the
known hammer drilling machines. Sliding friction forces between the
drilling spindle and the coupling sleeve only occur when the latter
is stationary during idling in the hammer drilling mode or during
pure drilling operations. The plunger spring means effecting the
hammering movements of the plunger in conjunction with the cam
members is supported by the coupling sleeve in such a way that, in
addition to the sliding friction originating from the oscillation
of the plunger, no further sliding friction arises due to the
spring means, but on the contrary the sliding friction in the
hammer drilling mode rather remains limited to the sliding surfaces
guiding the plunger and the bearings supporting the drilling
spindle, apart from the sliding friction of the cam members.
The drilling spindle preferably includes a striker plate which
carries the drilling spindle coupling means and transfers the
hammer blows of the plunger to the spindle. This means that with
heavy loadings the striker plate may be changed without renewal of
the drilling spindle also being necessary at the same time.
The other said cam member is preferably carried by a lock nut
connected into a housing for the precussion mechanism. The cam
member and lock nut may be formed as one part, and the additional
expense of fitting a separate cam member is then not necessary.
The drilling spindle is preferably mounted in two roller bearings,
the inner race ring of the motor-side roller bearing supporting the
rotatable coupling sleeve of the drilling spindle in the hammer
drilling mode against the force of the plunger sping means. In this
way the axial forces arising when operating in the hammer drilling
mode can be transferred in a simple way through the coupling sleeve
to the inner race ring of this roller bearing. The percussion
gearing is fitted as a built-up unit into the gear housing and is
preferably screwed into the housing.
According to a further preferred feature of the invention, the end
of the drilling spindle to which the rotary driving force is
imparted carries an axially displaceable driving gear wheel which
preferably has an inclined tooth periphery urging it in the feed
direction. In this way, not only is the hammer action of the
machine increased and the input power requirement of the machine
reduced for a given hammer effect, since the plunger does not need
to be accelerated for every strike against the drilling spindle,
but also the overall length of the machine is reduced, since it
needs a shorter drilling spindle stroke, because the gear wheel
remains arranged in the feed direction as far as possible with all
strokes of the spindle.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more fully understood a
preferred embodiment of hammer drilling machine in accordance
therewith will now be described by way of example and with
reference to the accompanying drawing, in which:
FIG. 1 is a longitudinal sectional view through the whole gear
system of the hammer drilling machine;
FIG. 2 is a schematic sketch illustrating the principle of the
percussion gearing.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 2 the percussion mechanism of the hammer drilling
machine consists essentially of components grouped symmetrically
about a drilling spindle B. These components comprise a first cam
ring N, an opposing cam ring G rigidly connected to a plunger S,
and a spring F which throws the plunger S against a stroker plate T
by the action of the spreading of the two cam rings on rotation of
the one relative to the other, e.g. by relative rotation of two
sets of ratchet teeth sliding on one another, stressing the spring,
whereafter the closing of the cam rings upon further relative
rotation causes the spring to be unloaded and the plunger to be
thrown forward.
The drilling spindle 1 in FIG. 1 is so mounted, as indicated by the
arrows of movement, that it is both rotatable as well as
displaceable to a limited degree in an axial direction. It is
supported by two roller bearings 7, 8, the first of which is
arranged in an end lock nut 18 of the gear housing 12 and the
second of which is arranged in a gear housing flange separating the
percussion gearing from the rotary gearing. The axial movement of
the drilling spindle 1 can be blocked by means of a control pin 15
which is rotatably mounted in the machine housing in such a way
that a ball 16 positioned at the end of the drilling spindle can be
pressed by the pin against the drilling spindle counter to the
force of a spring 6 seated in the spindle. The rotation of the
drilling spindle is effected through a motor drive shaft 20 which
drives a gear wheel 13 and thence a rotatably mounted counter shaft
10, the latter driving a toothed gear wheel 9 which is axially
displaceable on the drilling spindle. The inclined teeth 14 of the
gear wheel 9 ensure that on turning the drilling spindle in a
clockwise direction the gear wheel runs constantly in the feed
direction against the inner roller bearing 8.
The drilling spindle 1 carries a striker plate 5 adjacent to the
outer roller bearing 7. This striker plate is rigidly connected to
the drilling spindle and is provided with coupling teeth 5' on its
axially inner face. Between the striker plate 5 and the inner race
ring 19 of the axially inner roller bearing 8, a coupling sleeve 11
is rotatably arranged on the drilling spindle and co-axial
therewith, the sleeve 11 having coupling teeth 11' at its outer end
adjacent to the coupling teeth 5'. This coupling sleeve 11 supports
in a non-rotatable but axially displaceable manner a plunger 3 and
a plunger spring 4. The latter presses at one end against a circlip
or snap ring 21 of the coupling sleeve 11 adjacent to the inner
roller bearing 8, and at the other end against the plunger 3, which
at its end remote from the spring 4 has a counter-pressur cam ring
3' non-rotatably connected to it. This counter-pressure cam ring 3'
engages with axial play A with a further cam ring 2 which is
supported by the lock nut 18. The cam rings are preferably formed
integrally with the components which support them or are machined
directly from them. The construction then works well with just two
roller bearings in spite of the movable parts of the percussion
gearing.
During standstill, idling and pure drilling, the axial play A is
always guaranteed, in order to avoid unnecessary friction, by
virtue of the fact that the spring 4 is supported at its two ends
directly or indirectly via the seating ring 21 for absorbing the
forces on the coupling sleeve 11.
In hammer drilling operations, the drilling spindle 1 is displaced
axially into the inside of the gear housing 12 counter to the force
of the spring 6 as a result of setting the drilling tool against
the stone to be drilled, so that the drilling spindle teeth 5' come
into engagement with the teeth 11' on the coupling sleeve 11 and
drive them. As a result the plunger 3 is also set into rotation and
the cam ring 3' which is rigidly connected to it turns relative to
the fixed cam ring 2. By virtue of the relative rotation of the two
cam rings, the plunger 3 is axially displaced counter to the force
of the spring 4 and thereafter is thrown against the striker plate
5 of the drilling spindle, as the crests of the cam ring disc 3'
first displace the plunger axially as far as possible and then fall
into the valleys between the crests of the cam ring disc 2. Each
time the cams move into the engaged position, the plunger 3
transfers the energy given to it by the spring 4 to the striker
plate 5, and thus to the drilling spindle 1 which passes this
energy to the drilling tool.
For a compact construction of the percussion gearing and for low
power input requirements, it is of significance that the driving
gear wheel 9 is axially displaceably mounted on the motor-side end
of the drilling spindle. Since as a result the mass of the gear
wheel does not need to be accelerated as well as the mass of the
drilling spindle by the plunger, the plunger can be kept smaller
while achieving the same impact force on a drilling tol. Besides
this, the whole machine can be made shorter in respect of the
drilling spindle stroke H, since the driving gear wheel 9 runs
constantly in the feed direction of the machine against the inner
race ring of the roller bearing 8. A short-period running of the
gear wheel 9 on the gear wheel 13 when set for hammer drilling,
that is with the drilling tool set against the stone to be drilled,
does not cause trouble and is immediately eliminated by the
inclined tooth arrangement 14.
If one wishes the machine to drill without the percussion gearing
being able to take effect, the control pin 15 is turned when the
machine is switched off or when it is idling so that the spindle
ball 16 is pressed against the small pressure of the spring 6 into
the drilling spindle at the end adjacent to the roller bearing 8,
so that, on drilling, the spindle is supported by the control pin
15. The coupling teeth 5' and 11' then remain out of engagement, so
that the percussion mechanism does not operate.
* * * * *