Rotary looper

Details Rotary looper Rotary looper

2000-11-20

2002-11-05

Walsh, Donald P. (Department: 3653)

Winding, tensioning, or guiding

Unidirectional winding and unwinding

Convolute coil

Reexamination Certificate

active

06474583

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a continuous pipe producing line, and more particularly, the present invention relates to a rotary looper, which preliminarily stores convolutions of a coil type strip (hereinafter, referred to as “strip”) uncoiled by an uncoiler toward a pipe mill, thereby enabling a newly supplied coil of strip to be continuously supplied to the pipe mill.
2. Description of Related Art
Conventionally, in a pipe producing line, a strip is uncoiled by an uncoiler and continuously fed into a pipe mill to produce a completed pipe. Due to the fact that there is an imposed limit, such as a predetermined amount of a strip, that can be continuously fed into the pipe mill, it takes 10 to 20 minutes at best for a unit coil of strip to be fully depleted and a new unit coil of a strip to be supplied into the pipe mill after the depletion. In this roll supply process, an operation of the pipe mill must be interrupted whereby a great deal of effort and time are required.
Therefore, as an alternative for enabling a strip to be continuously fed into a pipe mill without interrupting an operation of the pipe mill, it is regarded as the best method to weld a leading edge of a newly supplied unit coil of strip to a trailing edge of a currently depleted unit coil of strip.
However, since the pipe mill always takes out a strip at a constant rate and the strip has a moving speed corresponding to the take-out rate of the pipe mill, it is impossible, in actual fact, to butt and weld the leading edge of the newly supplied unit coil of strip and the trailing edge of the currently depleted unit coil of strip to each other, while the trailing edge of the currently depleted unit coil of strip is fed into the pipe mill.
To cope with this problem, a vertical type looper is disclosed in the art by Kent Corporation of the United States. In the vertical type looper, the strip is taken out by a separate device where it is to be preliminarily stored on the looper, at the time when a trailing edge of a unit coil of strip is nearly exposed to the outside at a rate which is faster than a normal feed rate of the strip. While the preliminarily stored convolutions of the strip are paid out to a pipe mill to be used in continuous pipe producing, the input of the strip to the looper is stopped for connecting, as by welding, a leading edge of a newly supplied unit coil of strip to the current unit coil of strip. A splicing station is provided between an uncoiler and the looper for making such a connection possible.
Such a conventional vertical type looper is, as shown in
FIG. 1
, installed on a base member
10
which is arranged between an uncoiler A and a pipe mill B. A pair of input pinch rollers
1
take out a strip
8
which is uncoiled by the uncoiler A, and an input guide
2
guides the strip
8
which is taken out by the pair of input pinch rollers
1
. A guide plate
3
is disposed adjacent to a downstream end of the input guide
2
. The strip
8
, which is taken out by the pair of input pinch rollers
1
, passes through the input guide
2
and the guide plate
3
. Then, the strip
8
travels inside a plurality of outside basket guide rollers
7
, by at least one turn in a state wherein it is brought into close contact with inside surfaces of the outside basket guide rollers
7
. Thereupon, the strip
8
forms a U-shaped free loop
8
′ as it is turned toward a plurality of inside basket guide rollers
6
. The strip
8
also travels outside the plurality of inside basket guide rollers
6
by at least one turn. Thereafter, the strip
8
is transferred around a series of spiral guide rollers
5
. After traveling along the series of spiral guide rollers
5
, the strip
8
is fed into the pipe mill B while being pulled by a pair of measuring rollers
4
.
In this course of transferring the strip
8
, by driving the pair of input pinch rollers
1
and thereby taking out the strip
8
into the looper at a speed generally faster than that of the strip
8
out of the looper into the pipe mill B, as the U-shaped free loop
8
′ orbits in a traveling direction of the strip
8
around a plurality of outside basket guide rollers
7
, outer convolutions and inner convolutions are accumulated or stored on the inside surfaces of the outside basket guide rollers
7
and outside surfaces of the inside basket guide rollers
6
, respectively, by the same number. At this time, the strip
8
is brought into close contact with the inside surfaces of the outside basket guide rollers
7
tightly, due to its spring back phenomenon. And as a result of tight frictional contact between the rollers
7
and the strip
8
, it is difficult for the strip
8
to further travel around a plurality of outside basket guide rollers
7
, when at least one convolution is stored on the inside surfaces of the outside basket guide rollers
7
. Consequently, the strip
8
is to be jammed in the input guide
2
or the guide plate
3
, or it may be impossible to further take out the strip
8
using the pair of input pinch rollers
1
. By reason of this, as the number of outer convolutions of the strip
8
increases, a diameter of a circular space which is defined by the plurality of outside basket guide rollers
7
should also be gradually increased as shown in
FIG. 1
by dotted lines, thereby to enable the strip
8
to be stored while being inserted into a gap which is continuously maintained between the outermost convolution and the inside surfaces of the outside basket guide rollers
7
. Also, due to the fact that the plurality of outside basket guide rollers
7
are moved outward as described above, as a distance between the innermost outer convolution and the outermost inner convolution varies rather than being constantly kept, the U-shaped free loop
8
′ can be bent rather than being flexibly curved. Hence, a diameter of a circular space which is defined by the inside basket guide rollers
6
should also be gradually increased as shown in
FIG. 1
by dotted lines, thereby to enable the strip
8
to be tensely stored on the outside surfaces of the inside basket guide rollers
6
.
On the other hand, an inside configuration for accomplishing the adjustment of diameters of circular spaces which are defined by the spiral guide rollers
5
, the inside basket guide rollers
6
and the outside basket guide rollers
7
, respectively, is as complex as the numbers of the spiral guide rollers
5
, the inside basket guide rollers
6
and the outside basket guide rollers
7
, as schematically shown in
FIG. 2
, and comprises a multitude of links L, each of which is driven by a hydraulic system or a pneumatic system. Thus, because fabricating and assembling procedures of a variety of components constituting the looper are greatly complicated and difficult to implement, fabricating cost is increased, a failure rate is elevated and noise is generated.
If an initial width between the innermost outer convolution and the outermost inner convolution is set large, such that the strip
8
has a small thickness, as an arc which is defined by the U-shaped free loop
8
′ as increased in its length, the strip
8
is likely to be bent rather than smoothly orbiting around the inside basket guide rollers
6
and the outside basket guide rollers
7
. Therefore, in the case of the strip
8
having a small thickness, cumbersomeness is caused by the fact that initial positions of the plurality of outside basket guide rollers
7
must be adjusted thereby to shorten the initial width between the innermost outer convolution and the outermost inner convolution.
Moreover, because the strip
8
which is taken out by the pair of input pinch rollers
1
must be always transferred to the looper in a direction which is tangential to an upper end surface of the lowermost outside basket guide roller
7
, the pair of input pinch rollers
1
, the input guide
2
and the guide plate
3
are structured in a manner such that they can be simultaneously lowered by the link arrangements as the plurality of outsid

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