[0001] The present invention relates to a gripping lifter intended for transferring metal
coils as in the preambles to claims 1 and 6.
[0002] The invention also relates to a method as in the preamble to claim 8 for lifting
metal coils and a method as in the preamble to claim 10 for transferring metal coils.
[0003] Below in the description and in the claims, the inner position of a projecting part
refers to the position of the projecting part in which it is located, in its entirety,
within the lifting arm. In turn, the outer position refers to the position of the
projecting part in which the longitudinal axis of the projecting part forms as great
angle as possible relative to the position of the longitudinal axis in the inner position
of the projecting part when said projecting part is viewed in the direction of Figure
2. A metal coil means in turn coiled metal, where underneath there is possibly a support
frame made of metal.
[0004] A variety of lifters for lifting metal coils are known in the art. One type of lifters
is provided with a hook at the end of the lifting arm, which is taken into the centre
hole of the coil to be lifted by means of pendulous motion. Because of the poor controllability
of the pendulous motion of the hook, said lifting arm is poor in job safety, neither
is it, because of the width of the lateral motion of the hook, otherwise appropriate
for use in crammed storage rooms or locations in which metal coils have to be placed
close to one another. A slightly more sophisticated lifting device model is known
from the EP application No. 971 022. The lifting device is provided with two L-shaped
lifting arms, being at the upper ends fixed to the support arms in horizontal plane.
The lower ends of the lifting arms are provided with detecting elements, with the
aid of which the centre holes can be located. After detecting the centre holes of
the coils, the L-heads of the lifting arms can be inserted into the centre holes by
adjusting the distance of the support arms. A lifting device such as this is provided
with fixed L-shaped lifting heads, whereby the gripping of the lifting device is relatively
large owing to the fact that the L-shaped heads of the lifter cannot be brought very
close to the metal coil before the centre hole has been detected. Said point limits
greatly the use of lifters because coils cannot be picked with the lifter from among
the coils packaged very close to each other without causing damage to the coils. The
width of the gripping motion required by the lifting device also takes a lot of the
valuable storage space when packaging metal coils in the storage. A problem related
to the lifter is also job safety because dangerous situations may arise because of
the projecting parts of the lifting arms of the lifting device when moving the lifting
arms in tightly packed storage rooms in up-and-down directions.
[0005] When loading metal coils, for instance in ships' holds or freight wagons for railway
transports, the valuable load is not permitted to swing during the transport, because
of which the coils have to be packed tightly against each other. Also in other types
of storage rooms, it is, because of the need to minimize the storage space, of advantage
to have the coils placed as close to each other as possible. With lifting devices
such as those mentioned in the foregoing, the metal coils cannot be packed close enough
to each other, but they have to be moved further in the storage by other methods.
Neither is it possible to lift with the lifting device any coils packed tightly next
to one another from a storage room without causing damage to the surface of the coils.
[0006] Also such lifting devices are known from the art in which the projecting parts on
the ends of the lifting arms can be pulled or turned into the lifting arms. However,
said lifting devices are intended, without a single exception, primarily for transferring
cable coils or equivalent light-weight coils, in which the coil material is not readily
damaged, neither will the weight of the coils cause structural problems for the lifting
device. Instead, the projecting parts of the lifting devices intended for lifting
a metal coil are required to be sturdy in structure and the lifting device are to
be provided with sufficient security equipment wherewith it is ensured that the valuable
coil material is not scratched during transfer. If lifting device designs provided
with turning projecting parts of the lifting arms are used, the turning mechanism
of the projecting part must be firm and long-lasting.
[0007] Metal coils have to be moved from one place to another so that they cannot move on
the projecting parts when being transferred. When metal coils are transferred in ports
and similar locations where the location of transfer and the size and quality of the
lifting mechanisms to be attached to the lifting device such as cranes vary , the
requirements to be met by the lifting device are increased: the lifting device is
required to be able to keep the metal coils firmly in place during the lifting operation
and it is required to be provided with security means wherewith it is possible to
ensure that the transfer of a metal coil is not started before the metal coil is steadily
located on the projecting parts. It must also be possible to interrupt a transfer
operation if the load moves on the projecting parts during the transfer, not to cause
damage to the metal coils.
[0008] From the Japanese patent publication No. 7-125969, a lifting device intended for
transferring coils is known in which the lower ends of the lifting arms are provided
with projecting parts turnable within the arms. The lifting device is primarily intended
for lifting cable coils, and so, it is not appropriate for lifting metal coils because
the lever structure intended for moving the projecting parts and the motion limiter
of the turning motion of the projecting parts are not appropriate for metal coils.
Neither is the lifting device provided with efficient security equipment to ensure
the position of the coil prior to and during the transfer of coils.
[0009] Furthermore, a lifting device intended for transferring coils, sheet metal boxes,
and equivalent goods is known from the German patent application No. DE-4217333. The
lifting device introduced in said application publication is impractical, complicated
in structure and too expensive in practice for use in transferring metal coils. The
lifting device includes projecting parts to be pulled inwards and located in the lower
ends of the lifting arms but it is not provided with security equipment essential
regarding the transfer of metal coils, wherewith damages to metal coils can be prevented.
Neither are the projecting parts provided with an efficient motion limiter of the
turning motion of projecting parts, because of which the lifting device is not appropriate
for heavy metal coils.
[0010] The purpose of the metal-coil lifting device design of the invention is to remove
the drawbacks found in the state of art.
[0011] Therefore, a first objective of the invention is to provide a lifting device intended
for transferring heavy metal coils, with the aid of which heavy metal coils can be
moved (packaged) tightly into a storage room, in order to minimize the storage space,
and on the other hand, to pick an individual metal coil from a tightly packed metal
coil store without a risk of damaging the metal coil.
[0012] A second aim of the invention is to provide a lifting device intended for moving
heavy metal coils, said device being provided with sufficient security equipment for
moving a metal coil safely, and without scratching the surface, from one place to
another.
[0013] A third aim of the invention is to provide a lifting device being better in job safety
than earlier.
[0014] A fourth aim of the invention is to provide a gripping lifter, the structure of which
is strong and firm enough in handling heavy metal coils, while as simple as possible
in structure. The simple structure reduces production costs and improves the competitiveness
of the product.
[0015] With the gripping lifter of the invention the above objectives are achieved.
[0016] The new gripping lifter of the invention is characterized in what is presented in
claims 1 and 6. The method of the invention for lifting metal coils is on the other
hand characterized in what is presented in claim 8. The method of the invention for
transferring metal coils is characterized in what is presented in claim 10. In the
dependent claims, advantageous embodiments of the invention are presented.
[0017] The gripping lifter of the invention intended for handling heavy metal coils is provided
with two lifting arms, being coupled at the upper ends to one or more support arms
substantially in horizontal plane, the lower ends of the lifting arms being provided
with centre hole detectors of the coil, and projecting parts. On the inner sides of
the lifting arms are positioned gravity-operated detecting elements of the sides of
the metal coil. The projecting parts have been rotatably carried on the lower parts,
their under edge forming part of the limiter of the turning motion of the projecting
part, and on the upper part thereof being attached a leverage machinery to be used
mechanically. The projecting parts are advantageously also provided with load detectors.
[0018] In the method of the invention for lifting metal coils, the lifting arms of the gripping
lifter are descended close to the sides of a metal coil until the detectors of the
centre hole detect the centre hole. The motion of the lifting arms of the gripping
lifter is stopped and the projecting parts rotatably carried in the lower parts are
turned to the outer position. Thereafter, the lifting arms of the gripping lifter
are approached towards each other until the detecting elements detect the outer sides
of the metal coil. The gripping motion of the lifting arms towards each other is stopped
when the inner sides of the lifting arms are clamped with desired force onto the outer
sides of the metal coil and thereafter, the metal coil on the projecting parts of
the lifting arms is lifted. In the method of the invention for transferring metal
coils, a metal coil hung on the centre hole on the projecting arms of the lifting
device is transferred to its storage location by descending it supported by the lifting
arms downwards. When the metal coil is in its storage location, the lifting arms are
lowered further until the detector of the centre hole detects the centre hole. Thereafter,
the projecting parts are turned into their inner position.
[0019] The operation of the gripping lifter of the invention is based on projecting parts
turnable into the arms on the lower ends of the lifting arms, said projecting parts
being provided with load detectors and an efficient limiter of the turning motion,
which projecting parts are connected to the detectors of metal coils and the centre
hole on the lifting arms. Therewith, considerable advantages are gained with the gripping
lifter of the invention when compared with other gripping lifters of the prior art.
[0020] The projecting parts of the lifting arms are turned at the rotatably carried point
of the lower part into the inner position and the outer position. While in the inner
position, the projecting parts remain inside the lifting arms. Therewith the advantage
is gained that the inner surface of the lifting arms remains smooth so that the lifting
arms will not scratch metal coils when picking metal coils packed tightly to each
other in a storage room.
[0021] When using turning projecting parts, also the advantage is achieved that the gripping
motion of the lifting arms can be considerably reduced in comparison with lifter designs
provided with fixed projections, so that metal coils can be transferred into crammed
locations or take out of crammed locations.
[0022] Moreover, such advantage is gained with the inside turnable projecting parts of the
lifting arms that the projecting parts do not cause extra job safety risk. The job
safety advantage is emphasized when working in tightly packed storage rooms.
[0023] In the gripping lifter of the invention, efficient detectors for detecting metal
coils, loads and centre holes are used as security equipment. Therewith it is ensured
that a metal coil is not transferred before it is resting firmly by its centre hole
supported by the projecting parts. With the aid of the security equipment, a transfer
of a metal coil can be interrupted if the centre of gravity of the load changes during
the transfer:
- With the centre hole detectors, it is ensured that the projecting parts are brought
precisely into the centre hole of the metal coil.
- With the load detectors and the centre hole detectors, it is ensured that the metal
coil is not lifted before it is resting firmly by the centre hole supported by the
projecting parts.
- With the aid of the load detectors, a lifting operation can be interrupted if the
centre of gravity of the metal coil changes during the transfer.
- With the detectors of the coil sides, it is ensured that the lifting arms are clamped
with desired force onto the sides of the metal coils.
[0024] When operating in normal conditions, in which the transfer locations of a metal coil
are kept approximately steady, the load detector can be omitted, while in varying
storage conditions it is advantageous to fix also a load detector on the projecting
part.
[0025] The projecting parts of the lifting arms are also provided with an efficent and structurally
long-lasting motion-limiter part to prevent the projecting part from turning too far
when being turned into the outer position. Thanks to the motion limiter of the invention,
the projecting part is able to carry larger loads and turning it into the outer position
is considerably more secure than in lifters of the state of art, such as in the patent
documents JP-7-125969 and DE-DE-4217333 mentioned in the preceding, in which a lever
mechanism and/or the inner side of the lifting arm are used as motion limiter.
[0026] Of the additional advantages gained with the gripping lifter of the invention, the
following aspects may be mentioned:
[0027] When a lifter is used for lifting a coil from a storage location, the projecting
parts on the lower sides of the lifting arms are not turned out until the detectors
of the centre hole detect the centre hole of a coil. When using an automatic centre
hole detector for detecting the centre hole, the significant advantage is gained that
no unreliable visual observations need be used for detecting the centre hole.
[0028] The lifting arms are turned with a mechanical-hydraulic lever mechanism. An advantage
of the mechanical-hydraulic lever mechanism lies in the adjustability of the turning
angel of the projecting parts compared e.g. with the gravity-operated lever mechanism
described in the above JP patent document.
[0029] The detectors of the metal coil sides are located on the inner sides of the lifting
arms, with the aid of which the gripping motion of the lifting arms can be stopped
at appropriate distance from the sides of the metal coil to be lifted. Therewith,
the advantage is gained that the space of the lifting arms, while closest to each
other, i.e. while clamped against the outer sides of the metal coil, can be adjusted
to conform to the coil size. The detectors of the coil sides are gravity-operated,
wherewith the advantage is gained that they are as simple as possible in structure.
[0030] The support arms of the gripping lifter of the invention can be functionally connected
to a variety of metal coil lifting device, such as port cranes, whereby the additional
advantage is gained that the same lifting device can be used in most varied conditions.
[0031] The gripping lifter may comprise two or more functionally connected gripping lifters.
Advantageously, a gripping lifter like this is provided with three functionally connected
gripping lifters. With this kind of connected gripping lifter the additional advantage
is gained that several metal coils can be transferred in one time from one place to
another.
[0032] The invention will be described below in more detail, reference being made to the
attached figures.
[0033] Figure 1 presents a gripping lifter of the invention when viewed in front view.
[0034] Figure 2 shows a longitudinal section image of the lifting arm as in Figure 1 in
front view.
[0035] Figure 3 shows the longitudinal section image III-III of the lifting arm of Figure
1 when viewed from the direction I of Figure 1.
[0036] Figure 4 presents another embodiment of the gripping lifter of the invention in front
view.
[0037] The gripping lifter 1 presented in Figure 1 comprises two elongated lifting arms
2a,2b, being slidably fixed on the upper parts 14a,14b onto support arms 3a,3b substantially
in horizontal plane. The lower ends 13a,13b of the lifting arms are provided with
detectors 4A and 4B of the centre hole 19 of the coil 5, and projecting parts 7a,7b
turnable inside the lifting arms. The projecting parts are provided with load detectors
6a and 6b. On the inner side 21 of each lifting arm, detectors 8a,8b of the metal
coil sides 17a and 17b are located, indicating a contact of the inner surfaces 21
of the lifting arms with the outer surface 17 of the metal coil to the control system
(not shown in the figures).
[0038] Figure 2, in turn, presents in greater detail the structure of the lifting arm 2
and of one projecting part 7 of the gripping lifter as a longitudinal sectional image.
The motions 7 of the projecting part into the lifting arm and out from the lifting
arm are controlled with a lever mechanism 12 comprising lever members 9 coupled to
a hydraulic cylinder (working cylinder) 10. The motions of the hydraulic cylinder
10 are transmitted to the turning projecting part 7 by means of a lever member 9.
In the upper part 7A of the projecting part, a spring-loaded load detector 6 is arranged
inside the projecting part which protrudes out of the upper surface 23 of the projecting
part when there is no load on the upper surface. In a situation of the figure, the
load detector is depressed into the projecting part because of the metal coil (not
shown) on the upper surface of the projecting part. The projecting part is rotatably
carried at the bearing point 18 of the lower part 7B. Part of the lower edge of the
projecting part has been formed into a motion limiter part 15 of the projecting part
for an outward turning motion. The motion limiter part forms the (turning) motion
limiter of the projecting part together with the response surface 22 on the lower
end of the lifting arm. The motion limiter prevents the projecting part from turning
about the rotatably carried point more than by angle alfa, that is, the angle between
the inner position of the longitudinal axis P of the projecting part and the outer
position thereof is at most alfa. In the figure, the inner position of the projecting
part is shown with a broken line.
[0039] Figure 3 shows furthermore details of the projecting part 7. The functions of the
hydraulic cylinder 10 of the lever mechanism 12 moving the projecting part are regulated
by the centre hole detector 4 by giving control signals to the control system (not
shown in the figures). The detector of the centre hole comprises a detecting member
giving control signals, that is, in this context an optical cell 4A and a signal receiver
4B corresponding thereto. The detector of the centre hole shown in the figure is provided
with two transmitter-receiver pairs, in which the signal receiver is located on a
first lifting arm 2; 2a and the equivalent receiver on the other liftign arm 2; 2b,
so that one lifting arm is always provided with one transmitter and one receiver.
The centre hole detector 4 is located on the inner side 21 of the lifting arm, in
the height direction of the lifting arm slightly higher than the upper surface of
the projecting part when the projec ting part is in the outer position, so that it
would be possible to control with the centre hole detector precisely the turning of
the projecting parts into inner position (see below). The load detector 6 is shown
in the outer position in the figure, i.e. in the position in which it is when no load
is resting upon the projecting parts.
[0040] Figure 4 shows a gripping lifter 11, comprising three functionally connected lifters
1a,1b,1c. It is possible to transfer 1, 2 or 3 metal coils from one place to another
with the aid of the gripping lifter 11.
[0041] Below, the operation of the lifter is described more in detail, reference being made
to the above-mentioned figures. A metal coil 5 is lifted with a lifter 1 as follows:
The projecting parts 7 on the lower ends 13 of the lifting arms 2 are in their inner
position when the lifting arms of the lifter are lowered. The lowering of the lifter
is performed with a separate lifting device such as port crane (not shown in the figures)
fixed on the support arms 3 of the lifter. The lifting arms can now be descended relatively
close to the outer srufaces 17 of a metal coil without having any risk of scratching
the metal coil because the inner sruface 21 of the lifting arms is smooth when the
projecting parts 7a and 7b have been turned into the inner position. Neither do the
projecting parts of the lifting arms cause any hazardous situations to the workers
while in this position. When the centre hole detectors 4 in the lower part of lifting
arms detect the centre hole 19 of the metal coil, the downward motion of the lifting
arms is stopped. The projecting parts 7 on the lower ends of the lifting arms are
turned from their inner position by angle alfa to their outer position by turning
the projections with the aid of a lever mechanism 12 around their rotatably carried
point 18. Thereafter, the lifting arms are moved in lateral direction along the support
arms 3 towards each other, so that the lower parts 13 of the lifting arms perform
a gripping motion. When the gravity-operated detectors 8 of the metal coil sides located
on the inner sides 21 of the lifting arms meet the outer sides 17 of the metal coil,
the control system is given a signal, on the basis of which it stops the gripping
motion of the lifting arms when the inner sides of the lifting arms are clamped at
desired force against the outer sides 17 of the metal coil. Thereafter, the lifting
arms are lifted so much that the load detectors 6 protruding from the upper surface
of the projecting part are pressed against the inner surface 20 of the centre hole
of the metal coil. When moving the metal coil, its centre hole 19 is resting by its
inner surface 20 on the upper surface 23 of the projecting part 7, said upper surface
being substantially in horizontal plane. After securing in this manner that the metal
coil 5 is resting firmly supported by the projecting parts 7, the metal coil can be
lifted and moved to a desired location.
[0042] The closest position of the lifting arms 2 of the lifting device, that is, the inner
position of the gripping motion, can be adjusted according to the outer dimension
h of the metal coil with the aid of the metal coil detectors 8 described above.
[0043] In turn, a metal coil is moved to a desired location in reverse order compared with
the lifting operation. A metal coil 5 resting on the projecting parts is lowered to
a desired location, for instance next to another metal coil. After moving the metal
coil to the desired location, the lifting arms 2 are still lowered so much that the
centre hole detectors 4 detect the centre hole 19. After detecting the centre hole,
the projecting parts 7 can be turned into the inner position inside the lifting arms
and the lifting arms can be lifted up.
[0044] The projecting part is turned into its outer position, that is, outside the lifting
arm every time when moving into the centre hole 19 of the coil, when lifting or lowering
metal coils. In turn, the projecting part has been turned into the inner position,
i.e. inside the lifting arm whenever no load is placed on the lifting means.
[0045] Only one embodiment of lifter of the invention is described in the preceding. It
is possible to arrange the lifting arms to act in telescopic manner, whereby the extent
of the gripping motion could be reduced more. Furthermore, in the present embodiment
the projecting parts are turned with the hydraulic cylinders and a lever mechanism
coupled thereto. In addition, the moving of projecting parts may equally be carried
out for instance with electric motors. The gripping motion of the lifting arms and
the turning motion of the projecting parts between the inner and outer positions an
possibly also the functioning of the lifting means attached to the support arms of
the lifter are controlled with a control system receiving the control signals from
the load and the centre hole detectors and from the detectors of the sides of the
metal coils. The lifting arms can be slided or moved on the lifting arms, for instance,
hydraulically or electromechanically. Similarly, the lifting arms can be rotatably
carried on the ends of the support arms so that the gripping motion of the lifting
arms can be obtained by arranging the support arms to be telescopy-operating. The
centre hole can be detected optoelectrically, inductively or in some other way.
1. Gripping lifter (1) intended for handling metal coils, provided with two lifting arms
(2; 2a, 2b), being at the upper ends (14) coupled to one or more support arms (3)
substantially in horizontal plane, the lower ends (13) of the lifting arms being provided
with detectors (4, 4A, 4B) of the coil centre hole and projecting parts (7; 7a, 7b),
characterized in that on the inner sides (21) of the lifting arms are located gravity-operated
detectors (8; 8a, 8b) of the sides of metal coil, said projecting parts being rotatably
carried at the lower parts (7; 7B), and the lower edge thereof being provided with
a limiting part (15) of the turning motion of the projecting part and at the upper
end thereof (7; 7A) being fixed a lever mechanism (12) to be mechanically used.
2. Gripping lifter according to claim 1, characterized in that the limiting part (15) of the turning motion comprises a shaped lower edge
of the projecting part, and that the lower end of the lifting arm is provided with
a response surface (23) of the limiting part.
3. Grippign lifter according to claim 1, characterized in that the load detector (6) is spring-loaded.
4. Gripping lifter according to claims 1 to 3, characterized in that the lifting arms (2; 2a, 2b) are at the upper ends attached to support arms
(3; 3a, 3b) operating telescopically.
5. Gripping lifter according to claim 4, characterized in that the support arms (3) can be functionally attached to a lifting device.
6. Gripping lifter (11) intended for transferring metal coils, characterized in that the gripping lifter (11) is provided with two or more gripping lifters (1)
being functionally interconnected.
7. Gripping lifter according to claim 6, characterized in that the gripping lifter (11) is provided with three functionally connected gripping
lifters (1; 1a, 1b, 1c).
8. Method for lifting metal coils (5),
characterized in that
- the lifting arms (2; 2a, 2b) of the gripping lifter are descended to the proximity
of the outer sides (17; 17a, 17b) of a metal coil until the centre hole detectors
(4) detect the centre hole of the metal coil, whereby the downward motion of the lifting
arms of the gripping lifter is stopped,
- the projecting parts (7; 7a, 7b) are turned around their rotatably carried points
(18) to the outer positions,
- the lifting arms of the gripping lifter are approached towards each other until
the detecting members (8; 8a, 8b) of the sides of the metal coil detect the outer
sides (17; 17a, 17b) of the metal coil,
- the gripping motion of the lifting arms towards each other is stopped when the lifting
arms (2; 2a, 2b) clamp the outer sides (17; 17a, 7b) of the metal coil with a desired
force,
- the coil positioned on the projecting parts of the lifting arms is lifted.
9. Method according to claim 8, characterized in that prior to lifting a metal coil, the lifting arms (2; 2a, 2b) are so lifted
that the load detectors (6; 6a, 6b) of the projecting parts detect the inner surface
(20) of the centre hole of the metal coil.
10. Method for transferring metal coils,
characterized in that
- a metal coil (5) being by its centre hole (19) hung upon the projecting parts (7;
7a, 7b) of the lifting arms of the lifter (1) is transferred to the storage location
by descending it supported by the lifting arms (2; 2a, 2b) downward,.
- when the metal coil (5) is in the storage location, the lifting arms are lowered
further until the centre hoile detector (5) detects the centre hole, and
- the projecting parts (2; 2a, 2b) are turned to the inner position.