JPH031234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in ingot tongs for use in vertically lifting, horizontally hanging, vertically hanging horizontally, or horizontally hanging and raising up ingots such as round, square, and flat slabs. It is something.

In general, ingot tongs, which are used as devices for lifting and transporting ingots, are equipped with a pair of claws for holding the target ingot on a pair of hanging arms from the tong body, and the tongs are first positioned above the target ingot. In this state, each claw is pressed against the ingot by moving the pair of arms in the approaching direction using the drive motor, and then when the tongs are pulled upward, the weight of the ingot acts on each claw pressed against the ingot. These claws are provided so that they can be pulled down relative to the arm, and when these claws are pulled down relative to the arm, they are guided by the arm to narrow the distance between the opposing pair of claws. By being supported, the configuration is such that even stronger clamping force (gripping force) can be obtained.

Therefore, the gripping force of the pair of claws on the ingot is derived from the weight of the ingot,
In addition, each claw usually has a
The structure is such that a biasing spring force is applied to the arm to bias it to a predetermined upper limit initial position.

By the way, the ingot tongs having such a structure sometimes causes the following problems during use. That is, considering the operation of lowering a predetermined ingot etc. from a suspended state onto a loading place, for example, a roller table, this involves lowering the tongs to fully place the ingot etc. on the table. This is then done by moving the pair of hanging arms apart using the drive motor to release the ingot gripping state by the pair of claws, but if the tongs are not lowered sufficiently at this time, part of the load of the ingot is removed. remains acting on the nail of the drooping arm,
In this state, forcing the drive motor to expand the hanging arm may cause damage to the mechanism, and as the hanging arm expands, the clamping suspension may be momentarily released. There is also a risk that an impact load will be applied to equipment such as the roller table below.

On the other hand, if the tongs are allowed to descend more than necessary, the hanging arm of the tongs will remain gripping the ingot with its claws (because tongs are generally used suspended from crane hooks). However, the crane's hook part loosened because it descended too far, and when the hanging arm was subsequently expanded, the tongs became free-standing. There is also the problem that the loosened part may fall instantaneously and collide with equipment such as a roller table below, causing damage to each other.

These problems are particularly problematic when the operation of lifting and lowering the tongs generally relies on the operator's intuition.

Therefore, it is desirable to provide a means to electrically and mechanically detect that the tongs have been lifted to a sufficient extent. For example, a load detection means using a load cell is installed on the crane side to It is detected that the lowering is completed, or the claw, which is provided to move downward relative to the hanging arm as described above, returns to the initial position by lowering the tongs. Some methods have been proposed, such as providing a means to detect this.

By these means, problems such as falling ingots and tongs can be effectively prevented.

However, according to studies conducted by the present inventors, it has been found that even with the above-described detection method, an unreasonable force may be applied to the drive motor when the hanging arms are expanded after being suspended. Considering the cause, the above method is basically to confirm that the claws of the tongs have returned to the position at the start of lifting with respect to the hanging arm, and the gripping force of the claws on the ingot that has settled is This is understood to be because the situation has not been completely released in this state.

In view of the above points, the present inventor aims to provide ingot tongs in which the gripping force of the claws can be released by lowering the tongs a little further after the ingot is placed on the floor when the tongs are suspended. This is what led to the present invention.

Accordingly, the gist of the present invention to achieve such an object is to provide a method for each of the opposing inner sides of a pair of hanging arms that are provided on a beam so that the opposing distance between them can be contracted, closed, and expanded. , a claw holder including claws for gripping the ingot is assembled, and these claw holders are guided to move diagonally inward and downward from the initial rest position when the hanging arm rises due to the weight of the ingot gripped by the claws. In the ingot tongs, which are configured to move closer to each other to increase the gripping force, each of the pair of claw holders is moved from the initial rest position to an upper limit position slightly upwardly diagonally outwardly opposite to the downward movement direction. In the ingot tongs, the ingot tongs are provided movably relative to the hanging arm.

As a structure for making such a claw holder freely movable outward and upward from an initial resting position, for example, a biasing spring in a compressed state is built into the claw holder, and the lower end of this biasing spring is spaced apart from a part of the hanging arm. Although it can be configured so that they can be engaged with each other, it is not particularly limited to this configuration.

The present invention will be described below based on embodiments shown in the drawings.

In FIG. 1, 1 is an ingot to be lifted, and 2 is a hanging ring suspended from a crane hook (not shown), which is fixed at the center of beams 3 and 3'. Reference numerals 4 and 4' denote hanging arms that are slidably mounted on the beams 3 and 3' by drive motors (not shown) in a manner that they can be contracted and closed, and expanded and moved away from each other in the left and right directions in the figure, and each hangs downward from the beam. The lower end portion is provided with a claw for holding the ingot 1, which will be described later, and a guide/support mechanism for the claw holder.

An example of a mechanism for retracting, closing, and expanding the hanging arms 4, 4' is a drive screw 5, 5' that is driven and rotated via a motor, torque limiter, sprocket, chain (none of which are shown), etc. Arm 4,
4', the internally threaded blocks 6, 6' are engaged and screwed together, and by rotation of the drive screws 5, 5',
Female thread blocks 6, 6' connect hanging arms 4, 4' to beams 3,
One example is one that is configured to slide to contract, close, and expand on 3'. Note that the symbols 5' and 6' in the above description are symmetrical with the symbols 5 and 6, and are therefore omitted from illustration.

Next, the claw guide/support mechanism, which is a characteristic part of the present invention, will be described.
4' have the same configuration, so only one side thereof is shown in the figures from FIG. 2 onwards.

FIG. 2 shows the tongs in a position where they are ready to be lowered and grip an ingot with the claws 7. This claw 7 is fixed at the lower end of the claw holder 8 on the opposing surfaces of the pair of claw holders, and the claw holder 8 is normally brought to an initial standstill by the biasing spring force of the biasing spring 9 due to the structure described below. It is assembled so that it can be moved diagonally downward (diagonally inwardly downward between a pair of opposing arms) as shown by arrow C in the figure, forming an angle θ with respect to the vertical direction, when lifting an ingot. That is, the biasing spring built into the cavity 8a of the claw holder 8 is supported by a bolt-shaped spring guide 11 whose upper end is supported by the claw holder 8 by a nut 12, and a spring guide support 10 assembled to the lower end of the bolt-shaped spring guide 11. The support shaft 13 is mounted in a compressed state between the spring guide support 10 and the upper end wall 8b of the hollow space 8a of the claw holder 8, and the support shaft 13 from the hanging arm 4 inserted into the hollow space 8a of the claw holder 8 is mounted in a compressed state. , so that the spring guide support 10 engages with the claw holder 8 to apply an upward spring force to the claw holder 8.

The claw holder 8 is provided so that it can be moved downward in the direction C by a guide (not shown) against the spring force of the biasing spring 9, and when the ingot 1 is gripped, the claw holder 8 is moved by a reaction force. Since the counterclockwise rotation moment shown in FIG. 2 will act, in order to stop the rotation due to this moment, a pair of rollers 14 are engaged with the upper inner surface 8c and lower outer surface 8d of the claw holder 8. , 15 are arranged and rotatably supported by the hanging arm 4.
Engagement surface 8 with rollers 14 and 15 on the claw holder 8 side
Since c and 8d also serve as surfaces that determine the downward movement direction of the claw holder 8, they form inclined surfaces that coincide with the direction of arrow C described above. The features of this embodiment are as follows:
In addition to the mounting structure of the biasing spring 9, the support shaft 13
A through hole 16 for fitting the nail into the cavity 8a of the nail holder 8 is provided in the moving direction of the nail holder 8 (C in the figure).
The hole is shaped like an elongated hole with respect to the direction (direction), and is provided so as to have a degree of play between it and the through hole 16 below the support shaft 13 in the normal resting state shown in the figure.

With the claw holder 8 and its guide/support mechanism configured as described above, the hanging arms 4, 4' on both sides are now retracted and closed from the state shown in FIG. 2 by a drive motor (not shown), as shown in FIG. 3. When the claws 7 are crimped onto the ingot 1 and then the tongs are pulled up with a crane hook so as to lift the ingot 1, a downward force is applied to the claw holder 8 due to the weight of the slab 1. For this reason, the claw holder 8
is moved downward and inward against the upward biasing spring force, so that the direction of downward movement is the same as the second direction as described above.
Since it is in the direction of arrow C in the figure, ingot 1 of claw 7
The clamping force increases as the claw holder 8 moves downward, and the downward movement of the claw holder 8 stops at a position where the weight of the slab 1 is balanced. The ingot is then cut into pieces. (See FIG. 4) At this time, the clamping reaction force acting on the claw holder 8 is supported by the rollers 14 and 15. In the figure, 17 is a striker for operating the limit switch 18, and 18 is a limit switch that determines the limit of downward movement of the claw holder 8. When this switch is operated, it means that the gripping force for the ingot 1 is properly obtained. Since there is no such thing, this is a guideline for redoing the clamping operation.

Furthermore, 19 is a second limit switch, and by engagement with the striker 17, the pawl holder 8 is placed in the initial rest position (the position shown in FIG. 2).
This indicates the upper limit of movement when moving upwards. This effect will be described later.

Next, to explain the case where the tongs are lowered and the ingot 1 is loaded and suspended on a predetermined equipment such as a roller table, the suspended ingot 1 is
By placing the ingot 1 on the ground, the claw holder 8 moves upward in the return direction from the downwardly moved position shown in FIG. 4, and when it returns to the position shown in FIG. be done.

However, when the hanging arm 4 is expanded from the state shown in FIG. As already mentioned, unreasonable force may be generated on the drive motor due to twisting of the part 6.

Therefore, in this embodiment, the lowering of the tongs is not stopped at the position shown in FIG. 3, but is continued further, so that the gripping force can be released. That is, according to the above-described structure of this embodiment, when the tongs are lowered from the position shown in FIG. It does not descend due to the condition
Therefore, the claw holder 8 is relatively moved upward to the upper side of the hanging arm 4, and this upward movement is in the opposite direction to the direction C in FIG. Therefore, along with the upward movement, it expands outward and disengages from the ingot 1. The upward movement of the claw holder 8 in this way will only cause the claw and ingot to come loose to a slight extent; on the other hand, if this upward movement is performed more than necessary, it may cause the engagement between the crane hook and the tongs to loosen. As already mentioned, in this embodiment, the limit of upward movement of the claw holder 8 can be detected by turning on the second limit switch 19. By turning on the second limit switch 19, the operator may be informed of this or the lowering of the tongs may be stopped. FIG. 5 shows the state in which the claw holder 8 has moved upward from the initial rest position relative to the hanging arm 4, and the spring guide support 10 of the biasing spring 9 is floating away from the support shaft 13. It is becoming more and more expensive.

If the hanging arms 4 are expanded in this state, the gripping force of the claws 7 on the ingot 1 is completely released, so the advantage is that no unreasonable force is generated on the drive motor, etc. .

As described above, according to the present invention, in the tongs configured to grip the ingot with the claws, the claws can be moved upward from the rest position before lifting the ingot, which is a relatively simple method. This has the advantage of being able to effectively release the gripping force when suspending the tongs, and the practical benefit is extremely large.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and is not limited to, for example, supporting the reaction force of the ingot gripping force by a pair of rollers, and furthermore, the present invention is not limited to the one in which the reaction force of the ingot gripping force is supported by a roller pair. It goes without saying that other configurations may be used for the means used for this purpose.

[Brief explanation of the drawing]

Drawing 1 is a front view including a partial cross section showing the schematic structure of the tongs to which the present invention is applied, and Fig. 2 to Fig. 5 are drawings.
The figures are diagrams sequentially showing the structural outline of a part of the hanging arm portion of the tongs and the positional displacement of the claw holder. 1: Ingot, 2: Hanging ring, 3, 3': Beam, 4,
4': Hanging arm, 5: Drive screw, 6: Female thread block, 7: Claw, 8: Claw holder, 8a: Blank space, 8
b: upper end inner wall, 8c, 8d: engagement surface, 9: biased spring, 10: spring guide, 11: spring guide support,
12: Nut, 13: Support shaft, 14, 15: Roller, 16: Through hole, 17: Striker, 18, 1
9: Limit switch.

Claims (1)

[Scope of Claims] 1. A claw holder that includes claws for gripping ingots on each of the opposing inner sides of a pair of hanging arms provided on a beam so that the opposing distance between them can be contracted, closed, and expanded. These claw holders are guided to move diagonally inward and downward from the initial rest position when the hanging arm rises due to the weight of the ingot gripped by the claws, so that they approach each other and increase the gripping force. In the ingot tongs configured, each of the pair of claw holders is provided movably relative to the hanging arm within a range from the initial rest position to an upper limit position slightly above the diagonally outer side opposite to the downward movement direction. Ingot tongs characterized by: 2. The ingot tongs according to claim 1, wherein the upper limit position of the upward movement of the claw holder is determined as the set position of a limit switch.