JPH0773723B2 - Manufacturing method of seamless pipe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a seamless pipe by a Mannesmann plug mill system.

[Prior Art] A conventional seamless pipe manufacturing line by the Mannesmann plug mill system is configured as shown in FIG. First, the billet of the shell is heated in the heating furnace 1 and pierced by the piercer 2 to form a hollow shell, and the elongator 3 enlarges the outer diameter and reduces the wall thickness. In the plug mill 4, the thickness is reduced and stretched by the hole type roll, and the reeler 5 is used to perform the uneven thickness correction polishing tube,
Furthermore, the outer diameter is reduced by a sizer 6 with a sizer 6 to make the outer diameter constant.

[Problems to be Solved by the Invention] However, in the reeler 5, it is necessary to secure a certain amount of wall thinning, that is, an amount of pipe expansion, in order to obtain a sufficient uneven thickness correcting and polishing tube effect. Further, the outlet side raw pipe size of the reeler 5 is given a predetermined outer diameter drawing amount by the sizer 6 because the succeeding sizer 6 determines the variation of the outer diameter of the raw pipe, the variation of the roundness and the like. It is necessary to have an appropriate outer diameter size.

Therefore, as the inlet side tube size of the reeler 5, the above is achieved in the reeler 5 and the size of the succeeding sizer 6 is increased.
In order to achieve the above, it is necessary to provide an outer diameter size.

However, since the plug mill 4 that defines the inlet side tube size of the reeler 5 is composed of a hole type roll, the outer diameter size obtained by the plug mill 4 is limited to the hole type size possessed, and is variable in a stepless manner. We cannot provide a large outer diameter size. This means that it is not always possible to reliably provide the optimum inlet side raw pipe size of the reeler 5, which is optimal for all seamless pipe making sizes, and the final product pipe will have a poor outer diameter, It causes inconvenience such as poor roundness and rough outer surface.

INDUSTRIAL APPLICABILITY The present invention surely provides a reeler inlet-side raw material pipe size that is optimal for any pipe manufacturing size of seamless pipe, and manufactures a good product pipe such as outer diameter, roundness, and outer surface skin. To aim.

[Means for Solving the Problems] The present invention according to claim 1 is a method for manufacturing a seamless pipe, in which a billet is pierced by a piercer, then polished by a reeler, and an outer diameter is reduced by a sizer to a constant diameter. It was done like this.

According to a second aspect of the present invention, in the first aspect, the ratio of wall thickness / outer diameter of the seamless pipe to be piped is 0.1 or more.

[Operation] According to the first aspect of the present invention, the hollow shell formed by piercing the piercer to have a predetermined outer diameter is polished by the reeler. At this time, the piercer can provide an arbitrary outer diameter of the raw pipe by adjusting the shoe interval, in other words, can provide a desired raw pipe size in the reeler. That is, as the inlet side raw pipe size of the reeler, the reeler is capable of ensuring a certain amount of wall thinning, that is, the amount of pipe expansion, in order to obtain a sufficient uneven thickness correcting and polishing tube effect in the reeler. On the exit side after polishing the side element pipe, the following sizer determines the outer diameter variation, roundness variation, etc. of the element tube, so that the desired outer diameter reduction amount can be given by the sizer. It is possible to provide a size that can secure a sufficient outer diameter of the outlet side raw pipe. Therefore, it is possible to reliably provide the inlet side raw material pipe size that is optimal for any pipe making size of seamless pipe, and to manufacture a product pipe having good outer diameter, roundness, and outer surface skin.

According to the second aspect of the present invention, the technical idea of the present invention according to the first aspect can be more effectively utilized in the wall-size pipe forming process. The reason is that even a wall thickness size that could not be produced by the existing reeler motor capacity can be rolled without increasing the motor capacity.

[Embodiment] FIG. 1 is a schematic view showing an embodiment of the present invention.

The pipe making line in FIG. 1 is composed of a heating furnace 10, a piercer 20, a reeler 30, and a sizer 40. That is, billet 1
Is heated in the heating furnace 10 and pierced by the piercer 20 to form the hollow shell 2, the reeler 30 smoothes the uneven thickness, and the sizer 40 narrows the outer diameter to a fixed diameter to form the final product tube 3. .

FIG. 3 is a schematic diagram showing the rolling condition of the piercer.

The piercer 20 is configured by arranging two barrel-shaped rolls 21 at an angle with respect to the rolling pass line and arranging a cannonball-shaped plug 22 between both rolls 21 to pierce the billet 1. In the piercer 20, the outer diameter of the outlet side raw pipe can be adjusted by adjusting the distance between the shoes 23.

The reeler 30 is configured by arranging two cylindrical rolls 31 in an inclined manner with respect to the rolling pass line and arranging a long cylindrical plug 32 between both rolls 31 to polish the hollow shell 2.

The sizer 40 is configured by arranging a plurality of stands each consisting of a set of semicircular hole type rolls 41 arranged around the rolling pass line, while squeezing the hollow shell 2 at a constant outer diameter reduction rate, Make a constant diameter.

Next, the operation of the above embodiment will be described.

According to the above-described embodiment, the hollow shell 2 bored by the piercer 20 to have a predetermined outer diameter size is polished by the reeler 30. At this time, the piercer 20 can provide an arbitrary outer diameter of the raw pipe by adjusting the space between the shoes 23, in other words, can provide a desired raw pipe size in the reeler 30. That is, as the inlet side raw pipe size of the reeler 30, a constant amount of wall thinning, that is, a pipe expansion amount can be secured in the reeler 30 in order to obtain a sufficient uneven thickness polishing tube effect in the reeler 30, and On the outlet side after the inlet side raw pipe of the reeler 30 is polished, the following sizer 40 is used to determine the outside diameter variation, roundness variation, etc. It is possible to provide a size that can secure the outer diameter of the outlet side raw pipe sufficient to give the amount of diameter reduction. Therefore, it is possible to reliably provide the inlet side raw pipe size of the reeler 30 that is optimal for any pipe making size of the seamless pipe, and to manufacture the product pipe 3 having a good outer diameter, roundness, and outer surface skin. it can.

If the above-mentioned embodiment is applied to the thick-walled pipe making such that the ratio of the wall thickness of the final product pipe 3 to the pipe outer diameter is 0.1 or more, the pipe making is impossible due to the limitation of the reeler motor capacity. It is also possible to make thick-walled pipes.

[Advantages of the Invention] As described above, according to the present invention, it is possible to reliably provide the inlet side raw pipe size of the reeler that is optimal for any pipe making size of the seamless pipe, and to provide the outer diameter, the roundness, and the outer surface skin. Good product pipes such as

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a conventional example, and FIG. 3 is a schematic diagram showing a rolling condition of a piercer. 2 ... Element tube, 3 ... Product tube, 20 ... Piercer, 30 ... Reeler, 40 ... Sizer.

Claims (2)

[Claims] 1. A method for producing a seamless pipe, which comprises piercing a billet with a piercer, polishing the billet with a reeler, and then reducing the outer diameter by a sizer to a constant diameter. 2. The ratio of wall thickness / outer diameter of a seamless pipe to be formed is
The method for producing a seamless pipe according to claim 1, which is 0.1 or more.