JP6090251B2 - Steel pipe end inner surface cutting device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a steel pipe end inner surface cutting device for internally cutting a pipe end of a steel pipe, particularly a line pipe steel pipe.

  When the length of the steel pipe for line pipe is extended, the end of the pipe is welded and joined, but if there is a step at the joined part and its peripheral part, it tends to be a starting point for fatigue cracks. Therefore, in order to avoid stepping of the joint and its peripheral part, high roundness (that is, the variation from the nominal diameter of the steel pipe radius measured at one steel pipe end is within ± 0.1 mm, for example) Is required).

  In an inner surface care process of a steel pipe or the like, an apparatus (for example, see Patent Document 1) that cuts the inner surface of the pipe into a perfect circle over the entire length of the pipe is widely used.

  On the other hand, a technique for expanding and deforming the end of a steel pipe by roll shaping to make it round and have the same diameter is also known (see Non-Patent Document 1).

JP 2011-088243 A

Kishiguchi et al .: Nippon Steel & Sumikin Engineering Technical Report vol.4 (2013) p.39-45

  However, the conventional technique has the following problems. In other words, an apparatus that cuts the inner surface of a pipe into a perfect circle over the entire length of the pipe requires high roundness only at the pipe end (the pipe body length from the pipe end in the tube axis direction is 25 to 100 mm). If the steel pipe for a line pipe to be processed is processed, it is inefficient and also causes a deterioration in yield.

  Further, in the technique of expanding and deforming a steel pipe end by roll shaping to make a round shape and the same diameter, a step is likely to occur at the boundary between the expanded portion and the remaining portion. Also, when the end face shape of the tube end sandwiched between the shaping roll on the inner surface side and the casing on the outer face side tends to be a curved shape protruding outward, and it is necessary to add a process of flattening the end face after roll shaping There is.

  The present invention provides a steel pipe end inner surface cutting device capable of cutting a pipe into a perfect circle without generating a step on only the pipe end of a steel pipe, particularly a steel pipe for a line pipe, in view of the above-mentioned problems of the prior art. The task was to do.

The inventor has intensively studied to solve the above-mentioned problems, and as a result, has come to achieve the present invention having the following gist configuration.
(1) An internal cutting tool, a cartridge that supports the internal cutting tool and presses it against the inner surface of the steel pipe with a hydraulic mechanism, and supports the cartridge to supply pressure oil to the hydraulic mechanism and rotate around the pipe axis A steel pipe end inner surface cutting apparatus having a cutting head that moves in the axial direction and feeds the inner surface cutting bite from the pipe end to the end of the portion to be cut, wherein a copying roller is disposed on the outer peripheral portion of the cartridge, A tracing ring, which is a ring that causes the roller to follow the inner surface of the ring, is arranged so as to face the tube end coaxially with the tube axis, and the inner surface shape of the following ring is a perfect circle shape in the radial section, A steel pipe end inner surface cutting device characterized in that a tapered diameter-reduced portion on the near tube end side is connected to a constant diameter portion on the far tube end side in the axial cross section.
(2) The steel pipe end inner surface cutting device according to (1), wherein the steel pipe is a steel pipe for line pipe.

  According to the present invention, during the inner surface cutting process, the copying roller on the outer periphery of the cartridge rolls with the ring inner surface of the ring as the rolling surface, and as a result, the inner surface finished surface shape by the inner surface cutting tool becomes the ring inner surface shape. Correspondingly, a perfect circle shape is formed in the radial cross section, and a tapered reduced diameter portion is connected from the tube end to the constant diameter portion in the axial cross section. Therefore, according to the present invention, only the pipe end portion of the steel pipe can be internally cut into a perfect circle without generating a step.

It is the schematic of the cutting initial stage which shows an example for the form for implementing this invention. It is the schematic of the last stage of cutting which shows an example for the form for implementing this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a sectional view in the tube axis direction of a steel pipe end inner surface cutting device according to the present invention at the beginning of cutting and FIG. 2 at the end of cutting. As shown in FIGS. 1 and 2, a steel pipe end inner surface cutting device (hereinafter also referred to as the present device) according to the present invention includes an inner surface cutting bit 2 that is a cutting tool for internally cutting a steel pipe 1, and the inner surface cutting bit 2. The cartridge 3 is pressed against the inner surface of the steel pipe by the built-in hydraulic mechanism 5, and pressure oil (hydraulic fluid of the hydraulic mechanism) is supplied to the hydraulic mechanism 5 through the pressure oil supply path 6 while supporting the cartridge 3. Further, it is assumed that it has a cutting head 4 that moves in the direction of the tube axis while rotating around the tube axis and feeds the internal cutting tool 2 from the end of the tube to the end of the part to be cut.

  It is preferable to arrange 2 to 4 inner cutting tools 2 at equal intervals in the circumferential direction. The shaft hole of the hydraulic mechanism 5 is sealed on one side by a shaft sealing rod 9, and the pressing force applied to the shaft sealing rod 9 by pressure oil is opposed by a damper 10.

  Under the above premise, the apparatus according to the present invention is provided with a copying roller 7 on the outer peripheral portion of the cartridge 3, and the copying ring 8, which is a ring for copying the copying roller 7 on the inner surface of the ring, is coaxial with the tube axis. It is arranged facing the pipe end. It is preferable that 2 to 6 copying rollers 7 are arranged at equal intervals in the circumferential direction. The rotational axis of the copying roller 7 is parallel to the tube axis and is supported by the cartridge 3 via a bearing (not shown). In addition, the pressure oil supply path 6 provided in the cutting head 4 is connected to an external pressure oil supply pipe 12 via a rotary joint 11 so as not to hinder the rotation of the cutting head 4.

  Further, the tracing ring 8 has a ring inner surface having a perfect circular shape in the radial cross section, and a tapered diameter reducing portion 8b on the near tube end side is connected to the constant diameter portion 8a on the far tube end side in the axial cross section. It was assumed that it was a shape.

  Note that the diameter of the constant diameter portion 8a on the ring inner surface of the copying ring 8 is preferably “tube inner diameter + cutting depth × 2” or more and “tube outer diameter−tube thickness” or less. The length (“length” means the length in the tube axis direction, hereinafter the same) is preferably “cut portion (tube end) length × (0.3 to 0.7)”, The gradient (= radius decrement / length increment) of the tapered reduced diameter portion 8b is preferably 0.2 to 0.5.

  The hydraulic pressure force in the diameter increasing direction exerted on the cartridge 3 by the hydraulic mechanism 5 is balanced with the reaction force from the copying ring 8 via the copying roll 7. The oil pressure force in the diameter expansion direction is sufficiently larger than the reaction force that the inner cutting tool 2 receives from the surface to be cut of the steel pipe 1, and the copying roller 7 moves away from the ring inner surface of the follower ring 8 during the cutting process. There is nothing.

  At the initial stage of cutting, as shown in FIG. 1, following the rotation and feed of the cutting head 4, the copying roller 7 moves toward the tube end while rolling along the constant-diameter portion 8a of the inner surface of the ring. It follows the reduced diameter portion 8b. Then, the cartridge 3 is gradually reduced in diameter by the reaction force received from the tapered reduced diameter portion 8b via the copying roller 7, and the inner cutting tool 2 gradually decreases the distance from the tube axis. Therefore, at the end of cutting, as shown in FIG. 2, the shape of the tube inner surface after cutting by the inner surface cutting bit 2 is similar to the shape of the ring inner surface of the follower ring 8. That is, the inner surface shape of the pipe end after cutting by the inner surface cutting tool 2 is a perfect circle shape in the radial cross section, and the constant diameter portion on the far tube end side in the axial cross section is the near pipe end side in the axial cross section. It becomes the shape where the taper-shaped diameter-reduced part continued. Therefore, according to the present invention, only the pipe end portion of the steel pipe can be internally cut into a perfect circle without generating a step.

  In accordance with the above-described embodiment of the present invention, a pipe end portion (to-be-cut portion, target portion) for a steel pipe for a line pipe having an outer diameter = 250 to 500 mm and a “thickness / outer diameter” ratio = 0.024 to 0.148. (Length = 100 mm) only, constant diameter part cutting depth = 0.5 mm, constant diameter part cutting length = 50 mm, constant diameter cutting part, taper-shaped reduced diameter where cutting depth gradually changes from 0.5 mm to 0 mm Inner surface cutting was performed so that the inner surface of the tube with a continuous cutting portion was finished. As a result, a finished shape of the inner surface of the tube end portion with roundness within ± 0.08 mm and no step was obtained.

DESCRIPTION OF SYMBOLS 1 Steel pipe 2 Inner surface cutting tool 3 Cartridge 4 Cutting head 5 Hydraulic mechanism 6 Pressure oil supply path 7 Copying roller 8 Copying ring 8a Constant diameter part 8b Tapered reduced diameter part 9 Shaft seal rod 10 Damper 11 Rotary joint 12 Pressure oil supply piping

Claims (2)

  An internal cutting tool, a cartridge that supports the internal cutting tool and presses it against the inner surface of the steel pipe with a hydraulic mechanism, and supports the cartridge to supply pressure oil to the hydraulic mechanism and rotate around the pipe axis in the direction of the pipe axis. A steel pipe end inner surface cutting device having a cutting head that moves and feeds the inner surface cutting bite from the pipe end to the end of the portion to be cut, wherein a copying roller is disposed on the outer peripheral portion of the cartridge, and the copying roller is A tracing ring that is a ring that follows the inner surface is arranged so as to face the tube end coaxially with the tube axis, and the inner surface shape of the ring of the tracing ring is a perfect circle shape in the radial section, and an axial section. The steel pipe end inner surface cutting device is characterized in that a constant diameter portion on the far tube end side is connected to a tapered reduced diameter portion on the near tube end side.   The steel pipe end inner surface cutting device according to claim 1, wherein the steel pipe is a steel pipe for a line pipe.

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