[0001] The invention relates to a tool for a percussion apparatus, comprising an impact
surface intended to be impacted by an impact piston of the percussion apparatus and
a blade extending from the impact surface forward in the axial direction of the tool
and at least one guide surface in the axial direction of the tool, the guide surfaces
being intended to guide an axial movement of the tool with respect to the percussion
apparatus together and in contact with at least one corresponding guide surface of
the percussion apparatus.
[0002] In hydraulically, pneumatically or electrically driven percussion apparatuses of
different kinds, a tool is used which is impacted by the impact piston of the percussion
apparatus when different materials, such as concrete, stone, asphalt, tree or the
like are broken or cut. Such percussion apparatuses can also be used when penetrating
the ground, such as frozen ground, soft stone and so on. Both light manual percussion
apparatuses and heavy ones to be mounted on bases of different kinds are available,
the driving power of these apparatuses being generally obtained from separate power
units located at the end of hoses or cables.
[0003] When the percussion apparatus is in use, the impact piston of the apparatus makes
reciprocating impact movement guided by guides provided therein, such as control valves
or respective switches. At the lower end of the percussion apparatus, in the impact
direction of the impact piston, there is a tool, the receiving or impact surface of
which is impacted by the impact piston when the apparatus is in use, which impact
piston provides the tool with an impact impulse or force causing the desired material
to break. The tool moves guided with respect to the percussion apparatus in such a
way that the tool comprises guide surfaces and the percussion apparatus comprises
corresponding guide surfaces, the surfaces gliding with respect to each other in the
axial direction of the tool and keeping the tool in the right position with respect
to the percussion apparatus. Guide surfaces can be formed directly on the percussion
apparatus and the tool. The guide surfaces may also comprise changeable wear sockets
or a coating, as the guide surfaces of the tool known at present. The material can
be tempered steel, cast iron, bronze plastic, bronze teflon, various ceramics or the
like.
[0004] The tools used in the known solutions are generally rather thin and long and their
ends facing the impact piston are mounted in a space formed at the front end of the
percussion apparatus, where their movement and position are guided by means of various
wear sockets or the like. This leads to that bending stresses in the tools become
rather strong and the total length of the apparatus becomes rather long. These facts
are in many cases detrimental and a thin tool often causes unnecessary breakages of
the tool, which raises the costs of equipping and also causes delays in the work.
In addition, because of its length, the percussion apparatus is more difficult to
handle or to place in small or narrow spaces.
[0005] The object of this invention is to provide a tool and how to guide this tool with
respect to the percussion apparatus in such a way that the known drawbacks are avoided
and a reliable and safe solution is achieved. The tool according to the invention
is characterised in that the end of the tool intended to face the percussion apparatus
comprises a socket-like guide portion dimensioned in such a way that the front end
of the percussion apparatus for the tool can be placed within the socket-like guide
portion and that at least one guide surface is formed at that end of the socket-like
guide portion which faces the percussion apparatus.
[0006] An essential idea of the invention is that the tool end facing the impact piston
is formed socket-like in such a way that the end of the percussion apparatus facing
the tool can be placed inside the socket-like portion of the tool. Another essential
idea of the invention is that a movement of the tool is guided by guide surfaces provided
on its socket-like portion by the aid of guide surfaces provided on the percussion
apparatus. Still another essential idea of the invention is that the impact surface
of the tool is within the socket-like portion of the tool so that the rear guide point
of the tool is situated backwards from the impact surface.
[0007] An advantage of the tool according to the invention is that the whole constituted
by the percussion apparatus and the tool can be made considerably shorter than the
known solutions. Further, it is possible to use a tool being more firm than those
of the known solutions, and therefore, this tool resists stresses better than the
tools of the known solutions.
[0008] The invention is described in greater detail in the attached drawings, in which
Figure 1 shows schematically an embodiment of a tool according to the invention constituting
a whole with a percussion apparatus, partly in section,
Figure 2 shows schematically a second embodiment of the tool according to the invention
at the front end of the percussion apparatus, partly in section,
Figure 3 shows schematically a third embodiment of the tool according to the invention
at the front end of the percussion apparatus, in section, and
Figures 4a to 4c show examples of some alternative cross-sections of a socket-like
portion of the tool on the line A - A indicated in Figure 3.
[0009] Figure 1 shows schematically a percussion apparatus 1, which can be hydraulically,
pneumatically or electrically driven. Inside the percussion apparatus 1 moves an impact
piston 2, the end of which can be seen in the section of the front part of the actual
percussion apparatus in the figure. At the front end of the percussion apparatus 1,
below that in the figure, there is a tool 3 comprising a pin-like part 3a in the middle
and an impact surface 4 to be impacted by the impact piston 2 at that end which faces
the percussion apparatus 1. At the front end of the percussion apparatus 1, there
is further a surrounding guide 5. The tool 3, in turn, comprises a socket-like guide
portion 3b extending outside and around that guide 5 end which faces the tool 3 and
thus also around the front end of the percussion apparatus 1. The front end of the
tool comprises a blade 3c, which can be shaped in different ways and is suitable for
the purpose. For instance, the guide 5 can comprise, as shown in the figure, two separate
parts 5a and 5b to be joined together or it can be manufactured of only one part.
In practice, the guide 5 can also be a part of the percussion apparatus.
[0010] The tool 3 comprises two guide surfaces 6 and 7, the guide surface 6 being provided
on the outer surface of the pin-like guide part 3a and the guide surface 7 on the
outer surface of the upper end of the socket-like guide portion 3b. Correspondingly,
the inner surface of the front end of the percussion apparatus 1 comprises a guide
surface 8 for the guide surface 6 of the pin 3a and the guide 5 comprises, in turn,
a guide surface 9 for the guide surface 7 of the socket-like portion 3b. When the
tool 3 moves in the longitudinal direction of the percussion apparatus, it glides
back and forth under the influence of impacts of the impact piston 2 guided by the
guide surfaces 6, 8 and 7, 9, respectively. Between the guide 5 and the socket-like
portion 3b, there can be one or more seals 10, 12 preventing various fluids and also
dust from passing by.
[0011] The percussion apparatus 1 and the guide 5 are connected together for instance by
locking means 11 shown in the figures, which means can be any locking means known
per se, or the percussion apparatus and the guide 5 may be integral. Correspondingly,
the tool 3 can be locked in its longitudinal direction movably to the guide 5 in such
a way that it cannot get loose by itself, by using any locking method known per se,
such as locking pins 13 or the like, through an elongated opening 14 in the tool.
[0012] Figure 2 shows another embodiment of the arrangement according to the invention.
This corresponds to the embodiment of Figure 1 except that here the guide surface
6' which is closer to the point of the tool 3 is formed on the inner surface of the
socket-like guide portion 3b, in the vicinity of the front end of the socket-like
guide portion 3b, and, on the other hand, the corresponding guide face 8' is formed
at the front end of the guide, on its outer surface. In other respects, the components
of this embodiment and their operation are similar to those in Figure 1 and provided
with the same reference numerals, for which reason it is not necessary to describe
them here in further detail.
[0013] Correspondingly, Figure 3 shows a third embodiment of the arrangement according to
the invention. In this embodiment, the front end of the tool 3 is guided in the same
way as in Figure 2, but at the upper end of the tool, a guide surface 7' of the socket-like
guide portion 3b of the tool is formed on the inner surface of the socket-like guide
portion 3b, and in turn, a corresponding guide surface 9' is formed on the outer surface
of the guide 5. The guide surfaces 6, 7 may also constitute an integral axial longish
guide surface and, respectively, the guide surfaces 8' and 9' on the guide 5 facing
the percussion apparatus or on the body of the percussion apparatus may constitute
an integral guide surface. The guide surfaces may also be implemented in such a way
that there is an integral guide surface on one side and, on the other side, there
are two guide surfaces at a distance from each other for instance in the manner shown
in Figure 3. In other respects, the reference numerals, operation and structure of
the components of Figure 3 correspond to the same components in Figures 1 and 2.
[0014] Figures 4a to 4c show schematically some alternative cross-sections of the socket-like
portion 3b of the tool on the line A - A indicated in Figure 3. Figure 4a shows schematically
an angular alternative cross-section, which is advantageous in use, because it locks
the tool 3 non-rotatable with respect to the percussion apparatus 1 and thus stresses
less the locking means of the tool, which keep the tool connected to the percussion
apparatus. In this embodiment, a sliding surface 7' can be provided substantially
on the whole inner periphery or it may be provided for instance on four sides, which
make pairs perpendicular to each other. Pentagonal or hexagonal cross-sections or
cross-sections having different numbers of angles can also be used in the same manner,
of course.
[0015] Figure 4b shows, in turn, a typical conventional circular cross-section, in which
the sliding surface 7' is formed cylindrical on the whole inner surface.
[0016] On the other hand, Figure 4c shows an embodiment, in which the sliding surfaces 7'
are only parts of the cylindrical surface so that grooves remain between the parts
of the sliding surface, which grooves do not serve as sliding surfaces.
[0017] The embodiments of sliding surface illustrated in Figures 4 to 4c by aid of examples
can be applied in a manner obvious to one skilled in the art both to the inner and
outer surfaces of the socket-like portion 3b and also to the outer and inner surfaces
of the guide 5 or the percussion apparatus 1. Likewise, in the embodiment of Figure
4c, grooves between both the inner and outer sliding surfaces 7' can be used to prevent
the tool 3 from rotating with respect to the percussion apparatus 1.
[0018] The invention has been presented above in the description and the drawings only by
aid of examples and it is not in any way restricted thereto. As was stated earlier,
the power source of the impact operation of the percussion apparatus can be either
hydraulic, pneumatic or electric. The essential thing is that the tool comprises a
socket-like guide portion, within which the front end of the percussion apparatus
can be placed, and that guide surfaces facing back from the impact point of the impact
piston and supporting and guiding the tool during its movement are provided between
the percussion apparatus and the tool. The invention can also be applied in such a
way that the main part of the percussion apparatus is inside the socket-like portion
of the tool, the percussion apparatus being at its one end connectable for instance
to a working machine and remaining simultaneously almost entirely protected by the
socket-like guide portion of the tool. Further, the socket-like guide portion can
have a round, angular or oval cross-section or it can have another suitable form.
Because its form deviates from the round form, it stays automatically non-rotatable
with respect to the percussion apparatus. It is also clear that the guide surfaces
6/8, 6', 8', 7/9, 7', 9' do not need to extend as an integral surface around the tool
and the guide, respectively, but they can be shaped of parts of a guide surface at
suitable distances in different ways, between which parts there are no guide surfaces
in contact with each other. Likewise, various ways of lubricating the surfaces between
the tool 3 and the guide 5 can be implemented in manners known per se. The guide surface
7, 7' at that end of the socket-like guide portion 3b which faces the percussion apparatus
1 can either extend to the edge of the socket-like guide portion or to be at a distance
from it towards the point of the tool 3, depending on the situation.
1. Tool for a percussion apparatus, comprising an impact surface (4) intended to be impacted
by an impact piston (2) of the percussion apparatus (1) and a blade extending from
the impact surface (4) forward in the axial direction of the tool and at least one
guide surface in the axial direction of the tool (3), the guide surfaces being intended
to guide an axial movement of the tool (3) with respect to the percussion apparatus
(1) together and in contact with at least one corresponding guide surface of the percussion
apparatus, characterised in that the end of the tool (3) intended to face the percussion apparatus (1) comprises
a socket-like guide portion (3b) dimensioned in such a way that the front end of the
percussion apparatus (1) for the tool (3) can be placed within the socket-like guide
portion (3b) and that at least one guide surface (7, 7') is formed at that end of
the socket-like guide portion (3b) which faces the percussion apparatus.
2. Tool according to claim 1, characterised in that, in the middle of the tool (3), at the front end of the socket-like guide
portion (3b), there is a pin-like part (3a) intended to be pushed inside the front
end of the percussion apparatus (1) and that the impact surface (4) is located at
the end of the pin-like part (3a).
3. Tool according to claim 2, characterised in that at least one guide surface (6) of the tool is formed on the outer surface
of the pin-like part (3a).
4. Tool according to claim 1 or 2, characterised in that at least one guide surface is an inner surface (6') at the front end of the
socket-like guide portion (3b), in the vicinity of the impact surface.
5. Tool according to any preceding claim, characterised in that the guide surface (7) at that end of the socket-like guide portion (3b) which
is intended to face the percussion apparatus (1) is formed on the outer surface of
the socket-like guide portion (3b).
6. Tool according to any one of the claims 1 to 4, characterised in that the guide surface (7') at that end of the socket-like guide portion (3b)
which is intended to face the percussion apparatus (1) is formed on the inner surface
of the socket-like guide portion (3b).
7. Tool according to any preceding claim, characterised in that at least one of the guide surfaces (6; 6'; 7; 7') of the tool is substantially
cylindrical.
8. Tool according to any preceding claim, characterised in that it comprises at least on one level a plurality of guide surfaces located
on different sides of the socket-like guide portion (3b) of the tool (3), which guide
surfaces together form a guide surface guiding the tool (3) and keeping it in the
right direction.
9. Tool according to any preceding claim, characterised in that at least one of the guide surfaces (6; 6'; 7; 7') has a polygonal cross-section.
10. Tool according to any preceding claim, characterised in that the guide surfaces (7', 6') on the socket-like guide portion form in the
longitudinal direction of the socket-like guide portion (3b) an integral guide surface
having substantially the same length as the socket-like guide portion (3b).