Handling: hand and hoist-line implements – Grapple – Pivoted jaws
Reexamination Certificate
2000-06-09
2001-12-04
Walsh, Donald P. (Department: 3652)
Handling: hand and hoist-line implements
Grapple
Pivoted jaws
C294S119000
Reexamination Certificate
active
06325434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tongs apparatus, and more particularly to a tongs apparatus capable of providing supplemental holding force.
2. Description of the Related Art
Conventionally, when a crane or a like machine is used to suspend an object, such as a piece of titanium sponge, a log, or a piece of concrete, which has a relatively soft surface layer and a cylindrical shape that is difficult to grasp, or is used to change the orientation of the object from a horizontal orientation to a vertical orientation, or vice versa, a wire, a chain, or the like is used as a holding jig in order to perform the suspending and orientation-changing operation in preparation for various machining processes.
However, in many cases an object, such as a piece of titanium sponge, which is used as an industrial material is large and heavy, and therefore skill is required in an operation of holding such a large and heavy object, in a well-balanced manner, by use of a holding jig and suspending the object by use of the crane. Therefore, a suspending method which improves work efficiency has been desired.
FIG. 5
shows a tongs apparatus
100
, which is an example of a known tongs apparatus for suspending a heavy object. Generally, the tongs apparatus
100
is attached to a hook of a crane and is used to suspend an object, such as a piece of steel, aluminum, stone, or any other material.
The tongs apparatus
100
includes an engagement member
102
provided on the crane side of the apparatus
100
; an engagement pin
101
which engages a hook (unillustrated) of the crane; paired cross arms
104
for holding an object; tension bars
103
rotatably connected to the cross arms
104
; a frame
105
to which the cross arms
104
are rotatably connected; and a stopper
106
disposed under the frame
105
and capable of contacting the upper face of the object.
The tongs apparatus
100
is equipped with a lock mechanism consisting of a tong male key
110
a
and a tong female key
110
b.
The tong male key
100
a
is provided on the engagement member
102
side, and the tong female key
110
b
is provided on the stopper
106
. The cross arms
104
of the tongs apparatus
100
are held in an opened state by the lock mechanism.
The lock mechanism is locked through an operation of lowering a crane hook in a state in which the stopper
106
is placed on an object or a frame and the cross arms
104
are opened outward. That is, when the crane hook is lowered, the tong male key
110
a
enters the tong female key
110
b.
As a result, a projection provided on the tong male key
110
a
rotates, and thus, the lock mechanism is brought into a locked state. In a locked state, the cross arms
104
do not close even when the tongs apparatus
100
is pulled upward by the crane.
When an object is to be suspended by use of the tongs apparatus
100
, the tongs apparatus
100
in which the lock mechanism is in the locked state and the cross arms
104
are in the opened state is suspended from the crane. Subsequently, the tongs apparatus
100
is positioned above the object.
Subsequently, when the lock mechanism is unlocked, the cross arms
104
close due to their weights, so that the distal ends of the cross arms
104
come into contact with the object. The unlocking of the lock mechanism is effected through an operation of lowering the crane hook in a state in which the stopper
106
is placed on the object or the frame, so that the projection of the tong male key
110
a
rotates, and the tong male key
110
a
is released from the tong female key
110
b.
Thus, the lock mechanism is unlocked. When the crane hook is raised, due to the weight of the object and that of the tongs apparatus, the cross arms
104
intrude into the object, which enables holding of the object.
When the cross arms
104
are to be opened again after the object has been moved to a desired position, the crane hook is lowered such that the stopper
106
of the tongs apparatus
100
is placed on the object. When the crane hook is lowered further, the tension bars
103
and the cross arms
104
rotate about pins
108
and pins
109
, respectively, such that the angles formed between the tension bars
103
and the cross arms
104
become smaller. As a result, the cross arms
104
are opened.
However, in the tongs apparatus
100
shown in
FIG. 5
, the stopper
106
must be placed on the object or frame in order to open or close the cross arms
104
and unlock the lock mechanism. Therefore, when the stopper
106
is placed on a cylindrical object, such as a piece of titanium sponge, whose outer diameter is not constant, and whose outer circumference is uneven, the relative positions of the distal ends of the cross arms change depending on the outer diameter of the object, so that holding a desired portion becomes difficult.
In order to solve the above-described problem, a tongs apparatus as shown in
FIG. 6
has been proposed. In this tongs apparatus, cross arms are opened and closed through vertical movement of a motor-driven chain in order to hold an object at a desired position. Specifically, the tongs apparatus
100
shown in
FIG. 6
has a chain motor
114
disposed on the engagement member
102
provided on the crane side. A hook
112
is provided at the lower end of a chain
111
extending from the chain motor
114
. The hook
112
has a configuration that enables the hook
112
to engage a lifting pin
113
a
of a lifting block
113
provided on a base plate
107
. When the chain
111
is wound up by the chain motor
114
, the cross arms
104
open.
Further, a safety device (unillustrated) is added to the tongs apparatus
100
shown in
FIG. 6
in order to protect the chain motor
114
and the chain
111
. The safety device includes a limit switch or a proximity switch for detecting the fully opened state of the cross arms
104
and automatically stops the chain motor
114
when the cross arms
104
are fully opened.
When an object is suspended by use of the tongs apparatus
100
shown in
FIG. 6
, the engagement pin
101
is brought into engagement with the hook (unillustrated) of the crane. Subsequently, the crane is operated to lift the tongs apparatus
100
and move it to a position above the object. Subsequently, the chain motor
114
of the tongs apparatus
100
is operated in order to unwind the chain
111
. As a result, due to the weights of the cross arms
104
, forces act on the cross arm
104
inward or in a closing direction.
When the inner sides of the cross arms
104
come into contact with the object, the safety apparatus stops unwinding of the chain, while the chain
111
is slightly slackened. Thus, a holding position of the object is determined. Since the chain
111
is slightly slackened, due to the weights of the cross arms
104
, forces further act on the cross arms
104
inward or in a closing direction. At this time, if the chain is caused to slack excessively, the chain may entangle. Therefore, the limit switch or proximity switch detects such slack and adjusts the length of the unwound portion of the chain
111
in order to prevent such excessive slack.
Subsequently, the tongs apparatus is lifted by use of the crane. At this time, due to the weights of the object and the tongs apparatus, forces further act on the cross arms
104
inward or in a closing direction. In this manner, the object is held by the cross arms
104
, lifted by means of the crane, and changed in orientation.
When the tongs apparatus
100
shown in
FIG. 6
lifts a hard object such as a piece of copper, aluminum, or stone, the cross arms
104
can hold and suspend the object. However, when the cross arms
104
hold an object having a soft surface layer such as titanium sponge, the unwinding of the chain
111
is stopped immediately after the cross arms
104
come into contact with the surface layer, with the result that the object cannot be held reliably.
That is, lifting of the tongs apparatus is started before the distal ends of the cross arms
104
intrude into the inner hard portion of the o
Izumi Kazuo
Ono Yuichi
Takao Seiyu
Tanaka Kazuhiro
Chin Paul T.
Lorusso & Loud
Toho Titanium Co., Ltd.
Walsh Donald P.
LandOfFree
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