Abstract: The disk roll exchanging apparatus of the present invention includes a pair of disk frames 6 which support disk rolls 3 and which are capable of swinging open, a disk roll lifting device 12 for mounting the disk roll to and demounting it from the opened disk frames, and a horizontally moving device 18 for carrying and horizontally moving the disk roll lifting device, thereby allowing the disk roll to be mounted to and demounted from the opened disk frame. According to the exchanging method of the present, a pair of disk frames 6 that support disk rolls 3 are swung open sideways and are fixed at the open positions. Thereafter, a disk roll lifting device 12 carried on a horizontally moving device 18 is transferred to a disk roll engaging/disengaging position, and subsequently, the disk roll is lowered while releasing the disk roll from the disk frame, to thereby fixedly support the disk roll by the disk roll lifting device. The disk roll lifting device is then moved away from the disk roll exchange position.

Abstract: A piercer roll exchanging apparatus for use in a vertical piercing mill, as well as a piercer roll exchange method for use with the apparatus, which can automate the exchange of piercer rolls and which are suitable for flexible manufacture of small quantities of seamless steel tubes of a variety of sizes. The apparatus comprises a traveling carrier car capable of moving while carrying upper and lower cradles thereon, and a cradle shifter mounted on the traveling carrier car. The cradle shifter shifts the upper and lower cradles from a traveling end position to the interior of a piercing mill body. The cradle shifter includes a spacer clamp for clamping a cradle-to-cradle spacer and for adjusting the vertical position of the spacer, as well as a lower cradle clamp. According to the present invention, automation of piercer roll exchange work and shortening of the exchange time can be attained by means of a simple structure and without deterioration of workability.

Abstract: A piercing mill and cannon exchange method therefor which can automate exchange of a cannon and can cope with flexible production of a variety of differently-sized seamless steel tubes in small quantities. The piercing mill including means for pivoting a cannon holder which holds a cannon and means for sliding the cannon holder along a pass line, through combined above-mentioned means, the cannon holder is pivoted so as to come into alignment with the pass line, is slid along the pass line, and is clamped at a predetermined location. The cannon exchange is characterized in that a cannon holder which retains the cannon in the direction perpendicular to the pass line is pivoted so as to come into alignment with the pass line, is slid along the pass line, and is then clamped to the main frame of the piercing mill. Therefore, it become possible to automate exchange of a cannon in accordance with a changeover and to considerably reduce working hours.