JPH11130370A - Slab gripping method by slab lifter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slab gripping method capable of surely gripping a tapered slab placed by being decentered or obliquely traveled from a slab lifter. SOLUTION: In a slab lifter, a slab lifter or a tong or the like (referred to as a slab lifter or the like, hereinafter) fixed to an overhead crane or the like for carrying a slab by gripping it with at least two pairs of opened/closed arms, an arm pair for first clamping a slab is slightly opened by a preset amount, the slab is clamped again after the other pair clamps the slab, and thus tapered slabs obliquely traveled from the slab lifter or the like and not constant in width in a slab longitudinal direction are surely gripped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for gripping a slab by a slab lifter or a tongue (hereinafter referred to as a slab lifter) which is mounted on an overhead crane or the like and conveys the slab by at least two pairs of openable arms. It is.

[0002]

2. Description of the Related Art Japanese Patent No. 2,662,292 entitled "Hanging Tool Grab Mechanism" is a conventional technique related to a slab lifter for gripping a tapered slab in which the slab width is not constant in the longitudinal direction of the slab. This means that "when the slab is gripped, the claw holder rotates according to the taper of the slab, and the entire claw engages the slab. When the slab is a tapered slab and the claws hit one side of the slab, close the tongue lever,
When the pawl is pressed against the slab, the pawl holder rotates and the entire pawl engages the side of the slab. ].

[0003]

FIGS. 1 and 2 show an explanatory view (a front view) of a general slab lifter and a structural view (a side view) of the same arm opening / closing portion, respectively. A general slab lifter opening / closing mechanism will be described using this. The main beam 1 is suspended by a wire rope 5 via a sheave 4 on an overhead crane or the like. The main beam 1
The arm guide 2 has a built-in arm opening / closing screw 8 driven by an arm opening / closing motor 6 via a chain 7. The arm opening / closing screw 8 is threaded in opposite directions on the left and right, and the pair of arms 3 always opens and closes symmetrically about the main beam 1. In this manner, the pair of arms facing each other is generally opened and closed symmetrically by a mechanically integrated driving device. The same can be said for the link type tongs.

FIG. 3 shows the relationship between the slab and the slab lifter when the tapered slab 9 is parallel to the slab lifter. As can be seen from this figure, the center line 11 of the slab
And the center line 10 of the slab lifter matches,
It is indeed possible to grip the slab by means of the "hanging gripping mechanism" of Japanese Patent No. 2662292. However, actually, as shown in FIG. 3, it is extremely rare that the center of the slab coincides with the center of the slab lifter. Rather, as shown in FIG. 4, not only is the slab not parallel to the slab lifter, but also the center of the slab and the center of the slab lifter are shifted from front to back and left and right, that is, the slab lifter and the slab are generally misaligned. This is because it is extremely difficult to stop the crane by aligning the center of the crane with the center of the slab with both a manual crane and an automatic crane, and a deviation of about ± 100 mm usually occurs. Further, when the slab is supplied on a transfer table or the like, the slab is skewed during the transfer, and the slab and the slab lifter do not become parallel. Therefore, Patent No. 26
It is extremely difficult in practice to grip a slab by the "hanging tool gripping mechanism" of 62292.

In other words, as shown in FIG. 4, when the tapered slab is misaligned with the slab lifter and the arm is closed to grip the slab, the slab or the slab lifter as shown in FIG. Are attracted to each other by the closing force of the arm, so that the center line 10 of the slab lifter and one side of the slab are parallel to each other.

In FIG. 5, when the arm is further closed, the arm pair (wide side of the slab) 13 clamps the slab, and the relative positional relationship between the slab and the slab lifter is determined. Therefore, the arm pair (narrow side of the slab) 12 has not yet clamped the slab, but as described above, the slab lifter can only open and close the arm symmetrically with respect to the center line of the hanging tool. Even if the (slab wide side) 13 and the arm pair (narrow side of the slab) 12 can be operated independently of each other, the arm pair (narrow side of the slab) 12 cannot grip the slab, The lifter as a whole cannot grip the slab. This is not merely a matter of the orientation of the claw installed at the tip of the arm pair, and therefore, the prior art Patent No. 2662292 "Hanging device gripping mechanism" requires the center line of the slab and the slab lifter as shown in FIG. The slab can be gripped only in a very limited case where the center lines of the slabs are exactly coincident with each other, and it is impossible to handle a tapered slab by this technique alone.

As a method for solving such a problem, there is a method in which the main beam 1 and the arm guide 2 shown in FIG. 1 can be respectively turned. However, two turning devices capable of withstanding a load of several tens tons are provided. It is necessary to install the slab lifter, and the weight of the slab lifter increases by several tons, the rated lifting load decreases accordingly, and it becomes impossible to handle the slab of the conventional weight, and the height of the slab lifter is increased by the amount of the swivel. As a result, the lifting height is compressed, and as a result, the slab storage capacity as a warehouse is reduced, and the storage efficiency is greatly deteriorated. To secure the head and the rated load as before,
In some cases, the crane itself had to be renewed, which was costly.

[0008]

SUMMARY OF THE INVENTION The inventor of the present invention has renewed a slab lifter for handling a tapered slab as described above,
In order to avoid large-scale remodeling such as renewal of overhead cranes, it is possible to use a conventional straight slab (slab whose slab length is parallel) to handle tapered slabs. Invented a method of gripping a slab. That is, one of the present inventions is a method in which a slab is gripped by a slab lifter that transports the slab by at least two pairs of openable and closable arms attached to an overhead crane or the like, and a pair of arms that first clamps the slab is preset. Opening only a small amount, waiting for the other arm pair to clamp the slab, and re-clamping, the slab width is inclined with respect to the center line of the slab lifter, and the slab width is not constant in the longitudinal direction of the slab A slab gripping method using a slab lifter, characterized in that the tapered slab can be gripped reliably.

The means for solving the above problems will be described below. The reason that the tapered slab cannot be gripped by the slab lifter for straight slabs is that the wide side arm of the slab clamps the slab first, and even if the narrow side arm of the slab attempts to close, the rigidity of the lifter itself This is because the slab cannot rotate and the arm on the narrow side clamps the slab as a result.

The inventor pays attention to this point, and moves the slab relative to the slab lifter so that the arm on the narrow side can clamp the slab after the arm on the wide side of the slab clamps the slab. First, only the required amount of the wide-side arm on which the slab was clamped is released once, the narrow-side arm is clamped, and then the wide-side arm is clamped. We have invented a method that makes it possible to clamp the slab firmly at all. In this case, if the slab lifter does not have a control device or sensor for detecting the slab width,
The one that clamps the slab first is the wide arm of the slab, and the one that clamps the slab later is the narrow arm of the slab.

Also, when the slab is gripped, the width of the slab at the position gripped by each arm pair is measured, and a value obtained by adding the same value to each of the measured values is defined as an arm closing start opening. Another method of the present invention is a method of securely gripping a tapered slab in which the arm of the slab is inclined almost simultaneously with the slab lifter by clamping the slab and the slab width is not constant in the longitudinal direction of the slab. This is a method of gripping a slab by a lifter.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.
As shown in FIG. 4, "when the tapered slab is not parallel to the slab lifter", when the arms are closed, the slabs or slab lifters are displaced from each other due to the closing force of the arms, and the center line of the slab lifter as shown in FIG. 11 comes to a position parallel to one of the long sides of the slab. When the arm is further closed, the arm pair (wide side) 13 clamps the slab first. At this time, as shown in FIG.
Is released by α. At this time, α is given by the following equation. α ≧ {Cw / (2 × La)} × ΔW where α: primary opening dimension of arm Cw: width of claw of each arm La: interval between arm pairs ΔW: difference in slab width at the position where each arm pair grips

When the arm pair (wide side) 13 is opened by α, the slab is released from the slab lifter. Therefore, even when the arm pair (narrow side) 12 is closed, the slab is shifted by ΔW / 2 in FIG. Is possible, arm pair (narrow side) 1
2 makes it possible to clamp the slab firmly,
As shown in FIG. 7, all the arms can firmly hold the slab.

Another method of gripping the tapered slab is to measure the width of the slab at the position where each arm pair grips the slab when gripping the slab, or to obtain slab width information previously stored in a control device or the like. By using the values obtained by adding the same value to the arm closing start opening degrees, the arms of the wide slab and the arms of the narrow slab clamp the slab almost simultaneously, so that the center line of the slab lifter is There is a method of gripping a slab using a slab lifter, characterized in that it is possible to reliably grip a tapered slab which is inclined with respect to the slab and whose slab width is not constant in the longitudinal direction of the slab.

An embodiment of this method will be described with reference to FIG. FIG. 8 shows a positional relationship between the tapered slab and the slab lifter. In FIG. 8, As denotes a narrow side arm opening, Aw denotes a wide side arm opening, Ss denotes a slab width at a narrow side arm position, and Sw denotes a slab width at a wide side arm position.

Here, the slab width Ss at the position of the narrow arm is described.
And the slab width Sw at the wide-side arm position may be measured respectively or a value stored in a control device for a slab lifter or a crane may be used. In any case, when the slab width Ss at the narrow arm position and the slab width Sw at the wide arm position are grasped, the same value is added thereto and the narrow arm opening As and the wide arm opening Aw are respectively added. And

In this manner, the arm pair (slab narrow side)
12 and the arm pair (slab wide side) 13 interference (As-
Ss) and (Aw-Sw) have the same value. Here, since the opening and closing speeds of the arm pair (slab narrow side) 12 and the arm pair (slab wide side) 13 are the same, the arm pair (slab narrow side) 12 and the arm pair (slab wide side) 13 are simultaneously. The slab can be gripped.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of claim 1 will be described with reference to embodiments. In FIG. 5, an example will be described in which the distance between the arm pairs: La = 5000 mm, the difference in slab width at the position where each arm pair grips: ΔW = 250 mm, the width of the claws of each arm: Cw = 150 mm. α: The primary opening dimension of the arm is
As described in the above equation, since α ≧ {Cw / (2 × La)} × ΔW, α is 3.75 mm or more. In other words, in this case, the slab lifter attempts to grasp the slab and closes the arm, and first releases the arm pair on the side where the slab was clamped first by 3.75 mm or more on one side, for example, about 5 mm each, and then the other arm By closing the pair first, clamping the slab, and then closing it again, the slab can be reliably gripped.

[0019]

According to the method of the present invention, the tapered slab can be handled without a major modification of the slab lifter and the crane, and the tapered slab can be firmly gripped, so that the work safety is improved. It has become more secure.

[Brief description of the drawings]

FIG. 1 is an explanatory view (front view) of a general slab lifter.

FIG. 2 is an arm opening / closing part structure (side view) of a general slab lifter.

FIG. 3 is a diagram showing a relationship between a slab and a slab lifter when the tapered slab is parallel to the slab lifter.

FIG. 4 is a view showing the relationship between the slab and the slab lifter when the tapered slab is not parallel to the slab lifter.

FIG. 5 is a diagram showing a state in which an arm is closed when a tapered slab is not parallel to a slab lifter.

FIG. 6 is a view showing a case where the gripping method of the present invention is applied, and in which an arm pair (wide side) is temporarily opened.

FIG. 7 is a view showing a state where all arms clamp a slab.

FIG. 8 is a view showing a case where another example of the gripping method according to the present invention is applied, and showing a state where a pair of arms starts closing and opening;

[Explanation of symbols]

1: Main beam 2: Arm guide 3: Arm 4: Sheave 5: Wire rope 6: Arm opening / closing motor 7: Chain 8: Arm opening / closing screw shaft 9: Tapered slab 10: Slab lifter center line 11: Slab center line 12: Arm Pair (narrow side of slab) 13: Arm pair (wide side of slab) α: Primary opening dimension of arm Cw: Width of claw of each arm La: Spacing of arm pair ΔW: Slab width at position where each arm pair grips As: Narrow side arm opening Aw: Wide side arm opening Ss: Slab width at narrow side arm position Sw: Slab width at narrow side arm position

Claims (2)

[Claims] Claims: 1. An at least two overhead crane.
In a method of gripping a slab by a slab lifter that conveys the slab with the pair of openable and closable arms, an arm pair that first clamps the slab is opened only by a predetermined small amount, and the other arm pair clamps the slab. After waiting for the slab, it is possible to reliably grip the tapered slab which is inclined with respect to the center line of the slab lifter and whose slab width is not constant in the longitudinal direction of the slab. Slab gripping method by slab lifter. 2. Attach to an overhead crane or the like, and at least 2
In a method of gripping a slab with arms that can be opened and closed, the width of the slab at the position gripped by each arm pair when the slab is gripped is measured with respect to a slab lifter or the like that transports the slab in between, or a control device or the like is provided in advance. Using the slab width information that has been set, the value obtained by adding the same value to each arm is set as the arm closing start opening degree, and the slab is clamped almost simultaneously by the arms of the wide slab and the narrow slab. A method for gripping a slab using a slab lifter, characterized in that it is possible to reliably grip a tapered slab which is inclined with respect to a center line of the lifter and whose slab width is not constant in the longitudinal direction of the slab.