Method of cutting roll surface

Details Method of cutting roll surface Method of cutting roll surface

1990-03-13

1992-08-04

Schwartz, Larry I.

Turning

Process of turning

409199, 51289R, 82129, B23B 100

Patent

active

051349108

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a method of cutting a roll surface (rolling surface) and, in particular, to a method appropriate to the cutting of a roll of a three-roll type rolling machine (stretch reducer) used for manufacturing seamless steel pipes.
2. Background Art
The above three-roll type rolling machine comprises a plurality of (20 or more) roll stands arranged in tandem pattern, each incorporating three rolls and forming a central caliber therebetween. Referring to FIG. 5(a) which shows a roll stand, three rolls 10 . . . having axes i . . . made flush with one plane are arranged in different directions spaced at equal angular intervals of 120.degree. and form a central caliber 11 of a certain figure therebetween.
In this rolling machine, the caliber 11 of the roll stand decreases in size in a direction of advance from an upstream side to a downstream so that a pipe is gradually squeezed and rolled.
Describing the shape of the roll of this rolling machine in more detail, the roll surface is basically composed of a central caliber surface for forming the caliber 11 and of beveled surfaces 10a, 10b (hereinafter referred to as the "120.degree. surface") adjacent to both sides of the central caliber surface. The caliber 11 formed by a caliber surface 10c . . . of the three rolls tends to substantially define a triangular configuration on the upstream side, substantially defines a regular circle with the advance to the downstream, and finally defines a fully regular circle more specifically, the shape (at cross-section) of the caliber surface of a roll is an ellipse having a high degree of flatness (ellipticity: long radius/short radius) on the upstream side, gradually reduces in ellipticity with the advance to the downstream side, and finally attains an ellipticity of zero (0), turning into a fully regular circle.
Each roll on the stand is rounded at shoulders 10b, 10c on both sides of the caliber surface 10c, as shown in FIG. 5(b), for preventing scratches caused by the caliber edge during rolling.
An operation to cut such rolls while keeping the rolls mounted on the roll stand is reasonable as well as efficient, and it is usual to perform the operation in this way.
A known method of simultaneously cutting a plurality of rolls (hereinafter referred to as "set rolls") mounted on the stand is shown in FIG. 6. In this method, a cutter 3 fitted with three cutting tools 31 . . . directed outward (outward in the radial direction) is set on a revolving shaft (cutter shaft 30) so as to be positioned in the center (center 0 of the caliber 11) of the roll stand 1 having three rolls 10 mounted thereon, and the cutting tools 31 are adapted to make circular movement against the rolls 10 . . . in rotation and along the axial direction i of the roll by the rotation of the cutter shaft 30 (feed for cutting) so as to cut the caliber surface 10c, whereby a shape of the caliber surface to be obtained is various according to the amount of offset [a distance between the plane P (the plane including the axes i of three rolls and will be called "roll shaft arrangement plane" hereafter) and the position A of the tip of the cutting tool] indicated as e in the drawing. As the amount of offset e increases or decreases, the ellipticity increases or decreases, respectively, and a fully regular circle is formed at the offset amount of 0. Incidentally, this method is applicable when a disk cutting tool instead of three cutting tools 31 is used and feed for cutting is substituted by the back-and-forth movement of the cutter shaft 30.
This method, however, is to perform cutting of the caliber surface only and originally lacks a concept and capability of forming the shoulder 10b and 120.degree. surface 10a. The working of these parts must depend on the procedure that, apart from the working of the caliber surface, an exclusive cutting tool 4 is set as shown by the chain line in FIG. 6 and the continuous line in FIG. 7 after cutting the caliber surface 10c in the shape as fixed, and manually operated f

REFERENCES:
patent: 4742738 (1988-05-01), Strand
patent: 4827751 (1989-05-01), Holthoff

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