Crane and method for using crane

A crane comprises a base, a driving body for driving and controlling the crane disposed on the base rotatable in a horizontal plane, an articulated arm attached to the driving body pivotable in a vertical plane, and a clutching means for clutching the construction elements. The arm is folded and extended in a vertical plane. The clutching means is tiltably and detachably connected to a forward end of the arm. The crane further comprises a fixing means tiltably and detachably connected to the forward end of the arm as a substitute for the clutching means. The fixing means is capable of being fixed to the construction, so that the driving body can be moved while the fixing means is fixed to the construction.

BACKGROUND OF THE INVENTION 
The present invention relates to a crane which is suitable for example, for 
constructing a steel framework structure and a method for using the crane. 
More specifically, the present invention relates to a crane which has an 
arm having a plurality of pivotably jointed portions. 
Conventionally, cranes are utilized in order to construct steel framework 
structures for reinforced concrete construction. If the construction is 
multistoried or semi-multistoried, tower-cranes are used having a 
revolving turntable which can be lifted according to the height of the 
construction by a climbing mechanism. 
However, during construction of a steel framework structure using a 
tower-crane, steel bars etc. lifted by the crane swing to-and-fro, which 
makes it difficult to place the bars at proper positions and which 
necessitates the operator must be highly skilled. Furthermore, it is 
necessary to carry the construction elements such as bolts and nuts to and 
from another lift apparatus. These result in additional costs and a longer 
construction time. 
Therefore, there has been a recent demand for multi-operative cranes which 
can be utilized not only for lifting object such as steel bars but also 
for assisting in the construction operation by enabling control of the 
position and direction of the objects being lifted. FIG. 16 shows one of 
these multi-operative cranes comprising a mast 1 erected on the ground, a 
revolving turntable 2 installed on the upper end of the mast 1 rotatable 
about a vertical axis, an arm 3 disposed on the revolving turntable 2 for 
upward and downward movement, and a clutching mechanism 4 attached to an 
end of the arm 3 for clutching construction elements such as steel bars F. 
The arm 3 comprises four arm members 3a, 3b, 3c, and 3d, that are connected 
to each other to pivot about horizontal axes. These arm members 3a, 3b, 
3c, and 3d are pivoted by hydraulic cylinders 5. 
With such a multi-operative crane, not only can the mere lifting of steel 
bars or the like, be accomplished but also objects can be raised with 
control of their position and direction. 
However, the multi-operative crane has the following problems of which it 
is an object of the present invention to solve: 
Usually, for constructing steel framework structures, it is necessary to 
lift or move the crane depending on the situation of the construction site 
and the crane has to carry the raising object to the construction site. 
However, the conventional crane cannot be moved easily and consequently 
the range of reach of its arm 3 is limited. Therefore, the conventional 
crane is not always useful depending on the construction situation. Also, 
considerable cost and time for construction is needed since the components 
in the construction must be conveyed by lifting stages with a small lift. 
Furthermore, another crane must be utilized for moving and assembling the 
crane. Especially, if another tower-crane is utilized for this, a climbing 
mechanism only used for the tower crane is needed, so that additional cost 
is involved. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a crane and a 
method for using the crane which enable positioning and relocation to be 
easily achieved. 
It is another object of the present invention to provide a crane which is 
of utility in any step of the constructing operation of steel framework 
structure. 
It is a further object of the present invention to provide a crane and a 
method for using the crane, which can improve the carrying and 
installation operation of the elements used in a construction site, so 
that the cost and the term for construction can be reduced. 
According to an embodiment of the present invention, the crane comprises a 
base, a driving body for driving and controlling the crane disposed on the 
base rotatable in a horizontal plane, an articulated arm attached to the 
driving body pivotable in a vertical plane, and a clutching means for 
clutching the construction elements. The arm is folded and extended in a 
vertical plane. The clutching means is tiltably and detachably connected 
to a forward end of the arm. The crane further comprises a fixing means 
tiltably and detachably connected to the forward end of the arm as a 
substitute for the clutching means. The fixing means is capable of being 
fixed to the construction, so that the driving body can be moved while the 
fixing means is fixed to the construction. 
In use the crane, the clutching means is detached from the forward end of 
the arm. The fixing means is attached to the forward end of the arm after 
detaching the clutching means. The attached fixing means is fixed to a 
prescribed position of a construction. The driving body is moved to a 
prescribed location while the fixing means is fixed to the construction. 
Then, the fixing means is released from the prescribed position of the 
construction. 
More preferably, in the crane, the base includes an elongated post of 
adjustable height which stands upright on the base. The driving body is 
disposed on the post rotatably in a horizontal plane and movable upward 
and downward. 
In order to use the crane, the clutching means is detached from the forward 
end of the arm. The fixing means is attached to the forward end of the arm 
after detaching the clutching means. The attached fixing means is fixed to 
a prescribed position selected from one of the construction and an upper 
end of the post. The driving body is moved to a prescribed elevation along 
the post which stands on the base while the fixing means is fixed to the 
construction. Then, the fixing means is released from the prescribed 
position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the accompanying drawings, preferred embodiments of the 
present invention will be described hereinafter. 
FIG. 1 is a side view depicting a crane which comprises a base 10, a post 
11 standing on the base 10 and extendable in a vertical direction by means 
of adding accompanying post segments 11a, a driving body 12 disposed on 
the post 11 movable upward and downward, and a hanging means 13 having an 
articulated arm 21 installed on the driving body 12. 
The base 10 comprises a stage 10a of a rectangular shape for supporting the 
post 11 and two pairs of outriggers 10c. Each of the outriggers 10c 
comprises a horizontal arm 10b extended horizontally from the stage 10a, a 
leg 10e contacting the ground G, and a hydraulic cylinder 10d interposed 
between the arm 10b and the leg 10e for extending the leg 10e in a 
vertical direction. 
The post 11 on the base 10 is constituted by one or more post segments 11a 
of a cylindrical shape. The height can be adjusted by adding or 
subtracting the post segment or post segments 11a, or replacing a segment 
11a by a longer or shorter segment. In the figure, a relatively short post 
segment 11a with an end secured to the stage 10a of the base 10, is shown. 
Connection of the segments 11a is achieved by a bolt-nut joint. On the 
peripheral surface of the segment 11a, is formed a hole 11b for insertion 
of a fixing pin of a driving body 12. 
The driving body 12 comprises a table 12a having a hole through which the 
post 11 is inserted, and a revolving stage 12b which is rotatably 
installed on the table 12a and includes a power unit therebetween. The 
driving body 12 further comprises driving switches (not shown) for driving 
the controlling the crane. 
For raising and lowring the driving body 12, the articulated arm 21, which 
will be described later on, is set on a part of the building-construction 
or a top end of the post 11 and is controlled so as to bent in such a 
manner that a reaction force is applied to the location at which the arm 
21 is set, whereby the driving body 12 is raised or lowered along the post 
11. Then, the fixing pin provided in the table 12a is inserted into the 
hole 11b by hydraulic pressure to fix the driving body 12 to the post 11. 
A motor 12c is disposed under the revolving stage 12b, whereby the angle 
of rotation in the horizontal plane of the revolving stage 12b can be 
adjusted. 
The hanging means 13 comprises the articulated arm 21 which has a plurality 
of arm members connected end to end in series for pivotable movement about 
their respective joint portions, a supporting mechanism 24 installed at 
the forward end of the arms 21, and a clutching mechanism 23 detachably 
connected to a winding cable 22 wound around a winch 26 and passing 
through the articulated arm 21 and the supporting mechanism 24. As shown 
in FIG. 3, a fixing mechanism K can be installed on the hanging means 13 
as a substitute for the clutching mechanism 23 in order to set the forward 
end of the arm on the building-construction. 
Returning to FIG. 1, the arm 21 can be folded and extended by a plurality 
of driving means, each of which includes a hydraulic cylinder 25 disposed 
at the joint portion. The arm member 21a, which is the nearest of the arm 
members to the driving body 12, is connected pivotably via a hinge pin 12e 
to a bracket 12d disposed on the revolving stage 12b. The other arm 
members 21b, 21c, 21d, and 21e are jointed to one another via hinge pins 
21f disposed at the joint portions among the arm members 21a, 21b, 21c, 
21d, or 21e. 
At the joint portions, hinge members 21g, 21h, 21i, and 21j of triangular 
shape, are also installed respectively. An apex of each of the hinge 
members 21g, 21h, 21i, and 21j is connected to a rearward corresponding 
arm member 21a, 21b, 21c, 21d by a hinge pin 21k. Another apex of each of 
the hinge members 21g, 21h, 21i, and 21j is connected to the forward 
corresponding arm member 21b, 21c, 21d, or 21e, via a connecting link 21l. 
The remaining apex of each of the hinge members 21g, 21h, 21i, and 21j is 
connected to the rod 25a of the corresponding cylinders 25 via a hinge pin 
25b. The bodies of the cylinders 25 are connected respectively to brackets 
21m which are disposed respectively on the arm members 21a, 21b, 21c, and 
21d via hinge pins 25c. 
The winding cable 22 is routed through all arm members 21a, 21b, 21c, 21d, 
21e, and 21e, in such a manner that the cable 22 is supported between 
pairs of pulleys 27, each pair being disposed near the joint portion of 
the corresponding arm member, so that movement of the cable 22 is not 
obstructed by the arm 21 even if the arm 21 is folded. An end of the 
winding cable 22 is wound around a winch 26 mounted on the revolving stage 
26. A control unit S for controlling the power unit of the revolving stage 
12b is installed on the arm member 21e remotest from the driving body 12, 
so that the hanging means 13 can be controlled by an operator near the 
forward end of the arm 21. 
As best shown in FIG. 2, the clutching mechanism 23 for clutching steel 
bars and the like comprises a hook portion 23a hanging from the winding 
cable 22, a connector portion 23b hanging as one with the hook portion 23a 
and held in spline-engagement with the supporting mechanism 24, and a 
clutching portion 23c detachably affixed to the connector portion 23b. The 
clutching portion 23c can be chosen and replaced to suit the object being 
hung. In FIG. 1, the clutching portion 23c consists of a pair of vise like 
jaws. The jaws can be opened and closed by an actuator driven by an 
electric-generator or batteries mounted in the clutching mechanism 23. 
While spline-grooves 23d are formed on a conical upper portion of an outer 
peripheral surface of the connector portion 23b along the generating lines 
of the conical shape, annular grooves 23e are circumferentially formed on 
a cylindrical lower portion of the outer peripheral surface of the 
connector portion 23b, so that the clutching mechanism 23 can be engaged 
with the supporting mechanism 24 in a non-rotatable manner. 
The supporting mechanism 24 for supporting the clutching mechanism 23 
comprises a supporting cylinder 24a unitedly attached to the arm member 
21e, and a substantially cylindrical grip frame 24b pivotably connected at 
its ball portion 24d to the supporting cylinder 24a. 
On the inside of the supporting cylinder 24a, a spherical concave sliding 
surface 24c is formed as viewed in FIG. 2. The ball portion 24d of the 
grip frame 24b is rotatably engaged with the concave sliding surface 24c. 
The ball portion 24d of the grip frame 24b has two sets of rods 30 of 
which lower ends are held in ball-engagement with the upper portion of the 
ball portion 24d. The opposing rods 30 are disposed in parallel relation 
one another with the rods 30 angularly spaced at 90.degree. around a 
center hollow of the grip frame 24b in such a manner that a set of rods 30 
are opposed diametrically and another set of rods 30 are also opposed 
diametrically. The upper ends of the rods 30 are extendably disposed in 
the most forward arm member 21e. When a rod 30 is extended, the opposite 
rod 30 is retracted while the other set of the rods are not extended or 
retracted, thereby tilting the grip frame 24b in a direction shown by the 
arrow A--A or arrow B--B in FIG. 2. 
On an outer peripheral surface of the grip frame 24b, a plurality of double 
acting cylinders 31 are disposed at suitable spacing around the periphery. 
Lower ends of rods 31a of the cylinder 31 are secured to a slide shell 32. 
The slide shell 32 is moved along the grip frame 24b for slidable 
insertion of a lower portion of an outer peripheral surface of the grip 
frame 24b. When the slide shell 32 is at a lowermost position, an annular 
inner ridge 32a projecting radially inwards urges supporting balls 33 
radially inwards, each of which has a part projecting from a hole 24e of 
the grip frame 24b, so as to restrict the radially outward movement of the 
balls 33. The balls 33 are greater in diameter than that of the hole 24e, 
so that the balls 33 cannot pass throughout the hole 24e. When the slide 
shell 32 is at an uppermost position, a lower inner wide-diameter portion 
32b is at the same elevation to the supporting balls 33, so as to allow 
the radial outward movement of the balls 33 in a prescribed range. The 
slide shell 32 is always urged downwards relative to the grip frame 24b by 
a spring 35 towards the lowermost position defined by stopper 36. A limit 
switch 37 detects the lowermost position of the side shell 32. 
FIG. 3 shows a fixing device K for the hanging means 13. The fixing device 
K involves a fixing plate 39 which has bolt holes to enable bolting of the 
fixing plate 39 to a flange of a steel bar 4a by bolts 40 and nuts 41. The 
fixing plate 39 includes a hook portion similar to that shown in FIG. 2, 
hung from the winding cable 22 for connecting to the supporting mechanism 
24. The fixing plate 39 further includes a connector portion 23b also 
similar to that shown in FIG. 2 for spline engagement with the supporting 
mechanism 24. 
The structure of the fixing device K is not limited to that shown in FIG. 
3, provided that a forward end of the arm 21 can be set securely. 
Next, the operation of the crane will be described. The construction of a 
steel framework structure involves a frame-construction step including 
lifting of a steel bar by the hanging means 13 attached to the driving 
body 12, and assembling the steel bars to produced the steel framework 
structure; and a crane-moving step including attaching a forward end of 
the arm 21 to an upper floor of the steel framework structure by the 
fixing device K, and lifting the driving body 12 with the base 10 by 
folding the arm 21 in order to set the base 10 on the upper floor of the 
steel frame. 
FIG. 4 shows the frame-constructing step. In the figure, the second floor 
of the steel frame has been built already. That is, girders 4 of steel 
bars have been bridged between columns 2 which have been erected on the 
ground G. The base 10 of the crane is kept horizontally by means of the 
outriggers 10c. The direction and the position of a steel bar, to be fixed 
to the steel frame, is controlled by means of control of the rotation and 
folding of the arm 21, and the tilting of the clutching means 23 about the 
supporting means 24. 
In order to assemble the crane, the base 10 is mounted on the ground G and 
made horizontal with the outriggers 10c, and the driving body 12 is 
secured to the post 11 of the base 10. In order to lift the steel bars 4a 
which may be carried to the construction site by a truck, the arm 21 is 
controlled in horizontal and vertical directions and winch 26 winds the 
cable 22, so that the clutching mechanism 23 is disposed above the steel 
bars in a position to clutch one of the bars 4a. Next, the cable 22 is 
wound up by the winch 26, so as to raise the clutching mechanism 23 
together with the steel bar 4a gripped by the clutching mechanism 23 into 
the supporting mechanism 24 whereby the clutching mechanism 23 is 
supported to prevent rotation of the clutching mechanism 23. As the winch 
26 winds up the cable 22, the clutching mechanism 23 is raised and the 
connector portion 23b comes into engagement with the grip frame 24b. With 
the double acting cylinders 31 contracted and the slide shell 32 is 
located at the upper limit so as to allow a certain amount of movement of 
the supporting balls 33 in radial direction of the slide shell 32 so that 
when the connector portion 23b is raised, the supporting balls 33 move 
outward in the radial direction. 
When the connector portion 23b reaches the upper limit, the limit switch 37 
operates to interrupt the winding of the cable 22 by the winch 26 and the 
double acting cylinders 31 are extended to lower the slide shell 32. Then, 
the annular inward ridge 32a urges the supporting balls 33 so as to 
restrict the radially outward movement of the supporting balls 33 which 
engage with the annular grooves 23e of the connector portion 23b via the 
hole 24e of the grip frame 24b, so that the connector 23b is prevented 
from detaching. In this way, the clutching mechanism 23 is supported by 
the supporting mechanism 24. 
In this embodiment, since the position and the direction of the steel bars 
can be controlled by means of the control of rotation and folding of the 
arm 21, and rotation of the clutching means 23 about the supporting means 
24, the accuracy for the positioning of the steel bars can be improved. 
By repetition of the clutching-process whereby the steel bars are clutched 
by the clutching mechanism 23, the hanging process in which the steel bars 
are raised by winding the cable 22, and the controlling process for 
controlling the position and the direction of the steel bars by control of 
the rotation of the arm 21 and the clutching mechanism 23 and supporting 
mechanism 24 the third floor of the steel framework structure can be 
constructed. 
After that, the crane is moved up to the third floor. FIGS. 5 and 6 show 
the steps in moving of the crane. In FIG. 5, the forward end of the arm 21 
is set securely on one of the steel bars which is fixed to the steel 
framework structure using the fixing device K. Then, in FIG. 6, the base 
10 of the crane is raised by folding and rotation of the arm 21. 
For the movement operation, the fixing device K of FIG. 3 is used to secure 
the forward end of the arm 21 instead of the clutching mechanism 23. The 
fixing plate 39 of the fixing device K is fixed to the girder 4 by bolts 
and nuts. After fixing of the fixing plate 39 to the girder 4, the base 10 
is raised to position it on the third floor of the steel framework 
structure by controlling the folding of the arm 21 by the control unit S 
installed on the forward end of the arm 21. Then, the fixing plate 39 is 
released from the girder 4 and the fixing device K is replaced by the 
clutching mechanism 23. 
Next, as shown in FIG. 7, the crane, which is positioned on the third 
floor, is used to finish building the second floor of the steel framework 
structure. The crane builds upper floors of the steel framework structure 
as shown in FIG. 8 and then the process of raising the crane and 
constructing the steel framework structure is repeated so that the 
construction processes are continued. 
Moving and positioning the construction elements except for the fixing step 
is achieved by the turning and folding of the arm 21 and the winding and 
unwinding of the cable 22. Therefore, the construction elements can be 
conveyed to the floors lower than the floor on which the crane is mounted. 
Furthermore, the elements can be conveyed horizontally by extending the 
arm 21. Consequently another lift is not necessary for moving the 
construction elements. 
FIG. 10 depicts a modification of the crane. In this modification, the base 
10 comprises a stage 10g including the post 11, and flange portions 10h 
protruding from the stage 10g. The base 10 of the crane is fixed by 
clamping the flange portions 10h with nuts threaded onto anchor bolts 51 
embedded into a foundation 50. 
In order to lift the driving body 12, the height of the post 11 is adjusted 
by adding or subtracting the post segment 11a, or replacing the segment 
11a with another longer or shorter one. 
The procedure for lifting of the driving body is as follows: First, as 
shown in FIG. 11, the crane makes the steel framework structure with the 
steel bars 4a. Then, the post segments 11a are added to the post 11 by the 
arm 21. The fixing device K is secured to the forward end of the arm 21 as 
a substitute for the clutching mechanism 23 and is set securely on the top 
end of the post 11 or the steel framework structure. Then the arm 21 is 
folded so that a reaction force from the arm 21 is applied to the settled 
position, lifting the driving body 12 up the post 11. After raising the 
driving body 12 to a prescribed elevation, the driving body 12 is secured 
at that elevation and the fixing device K is released from the top end of 
the post 11 or the steel framework structure and replaced by the clutching 
mechanism 23. In this way, the crane can be raised to enable construction 
of higher floors of the steel framework structure. 
The above process for lifting the driving body 12 can be combined with the 
movement of the base 10 shown in FIGS. 13 and 14. 
FIG. 15 shows another use of the crane. In the figure, the crane is 
installed on the ground G after completion of the steel framework 
structure. The crane is used for raising and lowering construction 
elements using the clutching mechanism 23. 
As described above, the present invention has the following advantages. 
(a) The crane can be moved vertically and horizontally easily at the 
construction site, by substituting the fixing device for the clutching 
mechanism. The crane is more convenient than conventional cranes since the 
operator can move the crane to a desirable location depending on the 
construction situation. Furthermore, construction elements can be moved 
over a large distance by the clutching mechanism making it unnecessary to 
install other equipment to move the construction elements to and from the 
crane. Hence cost for a construction operation can be reduced. 
(b) The driving body can be raised and lowered since the height of the post 
is adjustable. Hence, the crane is more adaptable for construction 
situations since the operator can move the crane at a desirable location 
depending on the construction situation. Furthermore, the crane does not 
need a climbing means specially used for raising or lowering the crane so 
that the cost for whole apparatus can be reduced. 
(c) The efficiency of the operation can be improved. Therefore, the cost 
and duration of the construction operation can be reduced.