Metal working – Plural diverse manufacturing apparatus including means for... – Binding or covering and cutting
Reexamination Certificate
2001-01-23
2003-10-21
Wellington, A. L. (Department: 3722)
Metal working
Plural diverse manufacturing apparatus including means for...
Binding or covering and cutting
C029S03300H, C266S106000, C266S259000, C148S601000, C148S602000, C072S201000, C072S235000
Reexamination Certificate
active
06634073
ABSTRACT:
FIELD OF ART
The present invention relates to a train of equipment to continuously manufacture steel wire and, more specifically, to a train of equipment to continuously manufacture steel wire of carbon steel for machine structure use or alloy steel having an excellent cold working property.
The present invention relates to temperature controlling apparatuses for hot rolled steel wire and, in more detail, to temperature controlling apparatuses which are so designed that desired treatment patterns can be chosen, in one line, from among various kinds of cooling and heat retention treatments and heat treatments of wire in coils in accordance with the material quality and the final use of hot rolled steel wire.
BACKGROUND ART
A common process to manufacture steel wire comprises the steps of; heating a billet to a prescribed temperature in a reheating furnace, hot rolling the billet into wire of an intended size, winding the wire into continuous rings, cooling and appropriately heat-treating the wire, packing the wire into a bundled coil, and banding the coil. The bundled coil may undergo treatments such as annealing as required, before being shipped to a secondary work process. Various proposals have been made regarding the hot rolling and heat treatment steps of the steel wire manufacturing.
Looking at hot rolling of steel wire from the apparatus viewpoint, for example, a block mill, developed as a finish rolling mill for steel wire, has advantages especially of high speed rolling, compact equipment design and fewer surface defects. A block mill, in which 8 to 10 roll stands are closely arranged in tandem in one frame, can roll a material without twisting it and, for this reason, it has been introduced in many rolling lines recently.
Looking at the hot rolling of steel wire from the viewpoint of material property and structure, it is possible to refine a &ggr; structure by employing a method to hot-roll at as low a temperature as possible, for example not exceeding 800° C., and make the rolling finishing temperature lower than that in normal rolling practices (such a rolling method being hereunder referred to as controlled rolling). A technology has been known to soften the material of steel wire by dividing and granulating a laminated cementite of a pearlite structure through a combination of the above rolling method with slow cooling in the downstream process steps. However, since the rolling finishing temperature is usually 900° C. or higher in the normal practice of steel wire rolling, the refinement of &ggr; structure cannot be achieved, and it is necessary to anneal steel wire off-line to soften the wire material.
Japanese Patent No. 2857279 discusses a conventional example of using a rolling mill resembling the one employed in the present invention.
FIGS. 1 and 2
of the patent show an equipment configuration where a 4-stand post-finishing block mill is provided after an 8-stand finishing block mill to realize free-size rolling and precision rolling. In addition, the patent also proposes to provide a cooling apparatus at the entry side of the post-finishing block mill.
In the meantime, various methods have been proposed such as the one to wind and spread hot rolled steel wire into non-concentric rings and subject it to a direct heat treatment in the process of packing it into a bundled coil. The Stelmore method is an example of such proposals. Among these proposals, a means disclosed in Japanese Examined Utility Model Publication No. H4-37898 to construct a winder (laying cone), a transportation route for the wire in continuous rings and a heat retention furnace covered with a closed heat retention cover, and a technology disclosed in Japanese Examined Patent Publication No. H7-98977 to provide a line for normal heat treatment and another line for slow cooling, in a manner to allow switching, and to feed steel wire to a conveyer of a selected succeeding process, can be counted as conventional examples to treat steel wire in the form of bundled coils for the purpose of slow cooling after the winding.
With a finishing mill such as the block mill mentioned above, however, the total area reduction rate through 8 stands is as high as about 85%, and controlled rolling is practically impossible with hard materials generating large amounts of heat during working and used mainly for machine structure, such as carbon steels with 0.4% or more of carbon, alloy steels, spring steels and bearing steels. Further, in the Japanese Patent No. 2857279 mentioned above, a 4-stand block mill is installed as a finish rolling mill and a cooling apparatus is provided at the entry side of the mill. This arrangement, however, aims at suppression of abnormal growth of crystal grains and not at on-line manufacturing of soft steel wire having an excellent cold working property through a combination of grain size refinement by controlled rolling with a cooling means in a succeeding process, which is the feature of the present invention.
In the above-mentioned Japanese Examined Utility Model Publication No. H4-37898, a unique structure is employed where a winder is covered with a closed cover and, for this reason, there is a problem in terms of equipment costs, since a special apparatus is required exclusively from winding to slow cooling and thus most of existing wire manufacturing facilities cannot be used. Further, according to the above-mentioned Japanese Examined Patent Publication No. H7-98977, since pot type furnaces are employed for slow cooling of bundled coils, there are problems of difficulty in individually controlling the temperature, low productivity and the process not being suitable for continuous operation. In addition, since slow cooling starts in these conventional slow cooling lines from a comparatively high temperature of 850° C. or higher, there is a drawback that the line length inevitably tends to be long.
Besides the above, various methods of controlled cooling of steel wire are practiced during transfer on a conveyer after hot rolling, winding into rings using a winder having a laying head and spreading onto the conveyer. These methods include cooling by air blast, leaving to cool naturally (these two methods being hereunder simply referred to as, respectively, blast cooling and natural cooling), rapid-cooling actively with water or, otherwise, cooling slowly or retaining heat by covering a transfer line with a heat retention cover.
For example, Japanese Examined Patent Publication No. S60-55572 discloses a technology whereby hot rolled steel wire laid on a conveyer in rings is cooled with an air blast or a water spray and then, after being packed into bundled coils on pallets, is charged by a branching conveyer into an annealing furnace for a continuous heat treatment. Cooling with a water spray has a shortcoming in that it is incapable of cooling evenly and the wire material becomes inhomogeneous. What is more, this technology inevitably requires very large equipment occupying a huge area, resulting in a big disadvantage in the plant space requirement. The same publication discloses also a water cooling method used after forming the wire into bundled coils, but this method results in a highly inhomogeneous cooling.
Also, Japanese Unexamined Patent Publication No. H6-336620 discloses a technology whereby hot rolled steel wire laid on a conveyer in rings is rapid-cooled by directly submerging it into a cooling tank, then, after being packed into bundled coils, heat-treated (quenched and tempered) in a tempering furnace. This technology, however, employs a method to heat the bundled coils suspended on a hook conveyer. Since a maximum furnace atmosphere temperature in this method of transportation cannot surpass 650° C. or so as the bundled coils deform at a temperature exceeding 650° C., the method has a problem in that it is inapplicable to a quick heat treatment at high temperatures.
Further, Japanese Unexamined Patent Publication No. H8-193222 proposes apparatuses to selectively supply hot rolled wire to different lines for different kinds of heat treatment. According to the
Adachi Koji
Seki Ryuichi
Tanabe Koji
Tsuchida Kiichiro
Cadugan Erica E
Nippon Steel Corporation
Wellington A. L.
LandOfFree
Continuous production facilities for wire does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous production facilities for wire, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous production facilities for wire will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3168090