Note: Descriptions are shown in the official language in which they were submitted.
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1 HAND GRINDER AND VALVE THEREFORE
The invention relates to a valve comprising a dis-
placable valve body which can abut on a valve seat
and limit the flow of a medium.
Valves of this type are used for regulating and con-
trolling working mediums in the form of compressed
air and liquids utilized in air and hydraulic ma-
chines, respectively, of various types.
The invention furthermore relates to a hand grinder
comprising a valve as mentioned above.
Such grinders must be operated in a suitable and safe
manner and therefore it must be possible for the user
to adjust the valve in a convenient way dependent of
the situation of use in question.
In case of hand tools, the machine must therefore be
manually adjustable and preferably without impairing
the control of the tool in that damages may be incur-
red on tools and/or work.
In practice there are especially problems in connec-
tion with large and heavy hand tools making so heavy
demands on a secure grip that it is difficult to
control the flow of the working medium through the
valve without impairing the control of the tool. This
means that the tool must be removed from the place of
work, ie. be made non-machining, if a change of the
speed of rotation of the machine is to be adjusted by
the valve, when the tool can be made to machine again
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1 by bringing it nearer to the place of work.
It is the object of the present invention to facili-
tate the operation and thereby increase work safety
and to improve tool precision, and this is achieved
by means of a valve comprising a valve casing closed
at one end and having an inlet for the medium at said
end, and where on the inner side from said end there
is extending a stem provided with a valve body, said
body facing the end of the casing and cooperating
with a valve seat designed as a recess in a bush
wherein the stem can be axially displaced.
There is thus obtained a valve which can be designed
in a handle forming one of the holding positions on
a tool in that the medium can be admitted to the rear
of the handle at the closed end of the casing, e.g.
through a hose, and through the valve to the opening
in the bush and then, e.g. through a pipe, to the
working machine. From there the medium can be admit-
ted through a second handle, if any, which can like-
wise be provided with a handle. In this manner, the
pipe can form part of the tool e~uipment so that the
control and regulating functions can be effected by
means of one of the handles with a built-in regulating
valve. The operation of the valve takes place by an
axial movement of the valve casing.
By designing the valve casing as disclosed in claim
2, the valve becomes self-closing without any use of
auxiliary springs in that the pressure exerted by the
medium will close the valve. This gives a high degree
; of operating comfort and at the same time great
security of the valve being closed when the operator's
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1 hold of the handle is released.
By making the casing rotatable as disclosed in claim
3, the valve can be produced by such simple operations
as boring and turning.
By providing the casing with an inclined track as
disclosed in claim 4 and letting a pin move in this
track and thereby displace the casing relative to
the bushg the regulating can take place by a small
turn of the casing.
By designing the valve as disclosed in claim 5, it
can be constructed by simple components which are
partly cheaply produced and partly easily replaced.
As disclosed in claim 6, it is suitable to secure the
bush to an integrated part of the tool, thereby making
it possible to use the handle for regulating as well
as controlling the tool without the operator having
to remove his hands from the handle.
The invention also relates to a hand grinder which can
use the valve according to the the invention.
By designing a hand grinder as disclosed in claim 7,
there is obtained a very efficient and safe hand
grinder. By carrying the pressure medium to and from
the machine within the handle pipe, there is obtained
3 a high degree of security against breakages, and by
designing the handle pipe with handles at the ends,
the operator will keep in close contact with the
grinder which will furthermore be of a very simple
construction.
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1 By letting the axis of rotation of the spindle be
parallel to the longitudinal axes of the handles as
disclosed in claim 8, there is obtained a convenient
working position for the user. When using the grinder
in such a way that the ends of the handles turn down-
wards, the grinder can be safely carried over verti-
cal surfaces or the like.
By building the machine into the spindle as disclosed
in claim 9, the best possible use of the space between
the handles is made, just as the machine is well
protected against dirt.
A grinder according to the invention can suitably be
provided with a safety guard as disclosed in claim 10.
The user is thereby given a high degree of safety in
that the entire rear of the grinder is fenced.
By the grinding means disclosed in claim 11 comprising
an assembly of a plurality of slotted discs, an effi-
cient hand grinder is obtained, where the disc slats
can efficiently grind even very irregular surfaces.
Moreover, it is easy to replace the slotted disc
assembly since it need only be provided with new
grinding discs between the retaining discs. The whole
assembly is simply secured by a screw at the end of
the spindle. Such grinding discs are mentioned in the
applicant's US patent application USSN 395,001.
The invention will be further described in the follow-
ing with reference to the drawing, wherein
Fig. 1 is a sectional view of the valve in
its closed position along the line
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1 I-I in fig. 3,
Fig. 2 is the same valve, but in its open
position,
Fig. 3 is a perspective view of the valve,
Fig. 4 is a sectional view of the hand
grinder shown in Fig. 5 in the
direction of the arrows along the
line IV-IV in ~ig. 5, and
~ig. 5 is a top view of a hand grinder
according to ~ig. 4.
The drawing shows an embodiment of the invention
wherein the valve forms part of the control handle
or the guide 5 of a not shown machine-driven grinder.
The grinder is provided with a guide, one end of
which is shown in the drawing as the pipe 5 being the
end of the right or left part of the guide.
The working medium in the form of compressed air or
liquid is admitted to the machine through a hose 13
connected to the valve by a hose coupling 12 which
can be of any suitable type.
The valve itself comprises a casing 1 which is rota-
table about the longitudinal axis and which on the
outside can be covered with rubber 16 to improve
comfort and to ensure a firm grip.
The casing 1 is closed at one end so that an intake
chamber 11 is formed at the admission 12. A bolt 10
retaining partly a dished ring part 7 partly a spa~cing
pipe 8 retaining the ring part 7 at a given distance
from the end of the casing is screwed into the end
wall of the casing.
574
1 Moreover, an obli~ue through-going track 4, see espe-
cially fig. 3, is arranged in the casing. In this track
it is possible to displace a bolt head 3 so that a
turn of the casing gives an axial movement thereof
relative to a stationary bush 2.
This bush has been inserted in the casing so as to
extend a suitable distance into the casing and at the
end being provided with a circumferential groove wherein
a packing 6 is arranged providing a seal between bush
and casing.
At some distance therefrom the bush is provided with
a recess forming on its Qutwardly extending surface
extending at right angles to the axis a seat 14 in the
valve. The bolt 3 securing the casing in its position
is moreover screwed into this recess.
~inally, at its outwardly extending end the bush 2 is
provided with an external thread which can be screwed
into the pipe 5 and through which the working medium
is admitted when operating.
As appears from the drawing, the valve is assembled
with a packing 9 between the ring 7 and the pipe 8 so
that in the position shown in fig. 1 the valve has
completely cut off for the working medium to the
machine.
By turning the handle 16 towards the position shown in
fig. 2, the casing is moved towards the left and
thereby the valve body 7,8,9 away from the seat 14.
This makes it possible for the medium to pass through
the valve. The passage is continuously variable
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1 from a closed position to maximum whereby it is pos-
sible to precisely control the admission of wording
medium to the machine.
When releasing the handle, the casing on account of
the pressure of the working medium on the end surface
being ]arger than the end area of the bush will move
the casing to the right and thereby the valve body
towards the valve seat and so closing the valve. The
valve is therefore a self-closing valve which is
totally independent of compression springs or the like.
This renders a very high degree of security in that
the machine will automatically and quite reliably cut
ff admission of pressure medium to the machine which
will therefore stop. In case of a fall or some other
accident, the valve will close automatically and
thereby stop the machine.
To sum up it may be established that this simple and
reliable valve renders a continuously variable con-
trol of the machine power at the same time as full
control Or the tool operation is maintained. Further-
more, there is the abovementioned security of an
immediate stop of the machine in case the hold on
the handle should cease.
Figs. 4 and 5 show a hand grinder according to the
invention. The hand grinder is provided with a handle
3 pipe 17 being substantially U-shaped. In fig. 5 the
handle pipe 17 is shown with a bend so that the
handles 25,26 are situated closer to the user than
the center of the grinder. This to a high degree
facilitates the operator's use on the machine. In
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1 each end the handle pipe is provided with hand~les
25, 26, and the handle pipe 17 is moreover provided
with an inlet passage 18 and an outlet passage 19.
In case the handle pipe is assembled by two lengths
of pipe, the passages 18, 19 should mearly be the
inside diameter of the pipe.
In the handle 25 there is arranged a valve 21 accord-
ing to the invention, said valve having an inlet
nozzle 22 being suitably provided with a snap action
coupling for a pressure hose. In the handle 26 the
outlet passage 19 ends with an outlet opening 23.
This can e.g. be provided with a filter 24 or a
sound-absorbing devise just as the outlet opening
23 can be connected to a return hose for hydraulic
liquid.
In connection with the inlet passage 18 and the outlet
passage 19 the machine 20 is arranged within a hollow
spindle 27. This can suitably be driven by compressed
air, but a hydraulic machine can also be used.
- The machine 20 is controlled by the valve 21, said
machine making the spindle 27 rotate. A number of
grinding discs 28 are secured to the spindle by means
of retaining discs 31. These grinding discs can suit-
ably consist of sand paper or emery clothj but other
materials are available. The discs 28 are slotted so
that they comprise a plurality of slats. These slats
3 can be made double so that both sides are grinding.
Other types of grinding means are possible however.
'The spindle can be covered with wool or the like
for polishing purposes.
1 When the grinding means as shown in the drawing
rotates, it is possible to grind eve-n highly irregu-
lar or difficult work pieces, because the slats will
go into even very deep profiles and grind efficiently.
This makes the hand grinder according to the invention
very efficient for e.g. an intermediate grinding of
barnished work pieces such as furniture.
The hand grinder is moreover provided with a safety
guard 30. This is dome-shaped so as to encircle the
part of the grinding means facing the user. The safe-
ty guard 30 is suitably made from a light and strong
plastic material. The safety guard can be designed
in a great number of other ways in that they can be
semicircular or quadrangular.
The handle pipe 17 can conveniently be made of alumi-
nium. It is very important to reduce the weight of
the grinder so as to avoid the user becoming tired.
Due to its compactness and the possibility of using
light materials, the grinder can be made very light.
The grinding discs 28 are secured to the spindle 27
between retaining discs 31. These are tightened be-
tween a removable flange 33 and a fixed flange 32by means of a centre screw 29. When the grinding
discs 28 are worn out, they can therefore be replaced.
The retaining discs 31 are provided with a centre
opening fitting into the spindle 27. This can e.g.
3 be provided with a longitudinal toothing for sec-
uring the grinding discs being tightedly fixed or in
some other manner retained between the retaining discs
~ 31.
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1 The invention according to the application is not
limited to the embodiment shown in the drawing. A
hand grinder according to the application can be
designed in rnany different ways within the scope of
the invention such as these appear from the annexed
patent claims.
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