Metal deforming – By deflecting successively-presented portions of work during... – By use of deflector arranged to bend work transversely of...
Patent
1997-01-08
1999-08-24
Crane, Daniel C.
Metal deforming
By deflecting successively-presented portions of work during...
By use of deflector arranged to bend work transversely of...
72178, 72200, 7234296, 72377, B21B 1500
Patent
active
059411147
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a hot-rolling apparatus or system for producing from a steel strip an angle of stainless steel with a cross-sectional shape having a small outside radius at a corner portion thereof, and a rolling method using such hot-rolling system.
BACKGROUND ART
Angle steels or angles have been frequently used as a member of the structure for many years.
FIG. 1 is a view showing one example of the cross section of an angle produced by hot-rolling, in which reference character A represents the length of one side of a flange (A being hereinafter referred to as "flange"), t the thickness of the flange, r.sub.1 the inside radius of an angled corner portion, and r.sub.2 the outside radius of the corner portion. In general, these dimensions are stipulated by JIS (Japanese Industrial Standards) except for the outside radius of the corner portion. Those angles which are made of stainless steel for use in kitchens or chemical plants require an angled corner portion having an outside radius r.sub.2 not exceeding 1 mm (hereinafter simply referred to as "sharp edge") to secure the aesthetical appearance of a structure which is built up with the angles.
The method of producing angles is generally divided into two types; the first method is a hot-rolling method using a mill having grooved rolls between which a continuous cast bloom is passed, the other is a method of producing a light angle from a steel strip by means of a roll forming (bending) machine while the steel strip is still in hot or cold state.
The term "steel strip" is used herein to refer to a narrow band-like sheet material produced by slitting a wide steel sheet in the longitudinal direction.
FIG. 2 is a view showing a succession of passes (pass schedule) defined between two rolls for producing an angle by the hot-rolling method. In the production of the angle, a continuous cast bloom (billet) used as a blank is hot-rolled into the angled shape shown in FIG. 1 by making seven, eight or more passes between seven or eight pairs of grooved rolls.
In such rolling, when a material M' to be rolled passes between the grooved rolls, friction is generated due to a difference in peripheral speed between the grooved rolls at respective portions corresponding to flanges of an angle. However, the friction thus generated deteriorates surface qualities of the angle. To deal with this problem, an improved method of producing a stainless steel angle of excellent surface qualities has been proposed as disclosed in Japanese Patent Laid-open Publication No. 5-237503, which includes forming rolls disposed in front of the grooved rolls to bend a corner portion of the material.
FIG. 3 is a view showing a method of producing an angle from a steel strip via a cold-forming process. In this method, a blank sheet S is worked or processed by bending, and hence is not subjected to a reduction in thickness. Accordingly, the outside radius r.sub.2 of an angled corner portion is about twice the thickness of the blank sheet. For example, a stainless steel strip of 3 mm in thickness is formed into an angle having a flange thickness of 3 mm, a corner portion of the angle has an outside radius r.sub.2 of about 6 mm. The angle thus produced is not suitable for use in the kitchen.
When a blank sheet composed of a steel strip is to be shaped by hot rolling into an angle, the thickness B of a corner portion of the angle shown in FIG. 1 requires to be about 1.5 times the flange thickness t. This means that the use of a steel strip having the same thickness as the flanges of a rolled product is unable to realize rolling of an angle having a desired sharp edge. To realize the desired rolling, a steel strip having a thickness greater than the thickness of the corner portion should be used.
FIG. 4 is a view illustrative of the manner in which a rough-rolled material for an angle is produced from a steel strip having a thickness greater than the thickness of a corner portion of the angle, in which FIG. 4(a) is a view showing the cross section of the rough-rolled
REFERENCES:
patent: 1347917 (1920-07-01), Sheperdson
patent: 1978220 (1934-10-01), Otte
patent: 2184150 (1939-12-01), Parker
patent: 4433565 (1984-02-01), Preller
Crane Daniel C.
Sumitomo Metal Industries Ltd.
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