JP2953283B2 - Mandrel bar for seamless tube production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mandrel bar for manufacturing a seamless tube, and more particularly to a plug mounting portion thereof.

[0002]

2. Description of the Related Art A piercing plug used in a seamless pipe manufacturing method by a Mannesmann plug system and a piercing plug of a tilt rolling mill used in each rolling step and a rolling plug are fed between piercing or rolling rolls. Rotational force is applied from the material to be rolled by tilt rolling. At this time, in order to improve the dimensional accuracy of the material to be rolled, the material is rotatably mounted on the tip of the mandrel bar. A bearing structure for that purpose is described in, for example, Japanese Utility Model Laid-Open No. Hei 4-22101.

[0003]

In the conventional mandrel bar for manufacturing a seamless pipe as described above, the plug can be rotated. Therefore, compared to a type in which the entire bar rotates, the material to be rolled is reduced. The purpose of improving the dimensional accuracy or the service life of the plug has been achieved. But,
Since the outer diameter of the mandrel bar is determined by the dimensions and the like of the material to be rolled, the dimensions of the bearing are also limited.
As a result, in the service life of the bearing, particularly, the rolling reaction force is 80
Since the load of the thrust bearing is as large as 100 tons, the impact is too large and the impact is large, and further improvement is required for prolonging the service life.

The present invention has been made in order to solve such a problem, and aims at improving the dimensional accuracy of a material to be rolled without requiring a bearing having a special performance.
It is an object of the present invention to obtain a mandrel bar for seamless pipe manufacturing, which can extend the service life of a bearing, and is expected to improve productivity.

[0005]

According to the present invention, there is provided a mandrel bar for manufacturing a seamless pipe, wherein a tip of the mandrel bar and a plug mounting portion are formed in an L-shaped cross section from a surface receiving a thrust load. The two members are arranged so that they face each other with a gap and receive thrust loads.
A plurality of thrust bearing between the kicking surface and the annular member
Separately arranged, the multiple thrust bearings load on the same surface
Has the same function as the added thrust force
Are axially mounted via a double-row thrust bearing configured to share the same .

[0006]

According to the present invention, two annular members formed so that the cross-section of the mandrel bar tip and the plug mounting portion have an L-shape from the surface receiving the thrust load are opposed to each other with a gap. And thrust load
It a plurality of thrust bearings between the receiving plane and the annular member
The thrust bearings are located separately on the same surface.
The thrust that has the same function as the load is added
Since those are axially attached via a double row thrust bearing which is configured to share the preparative force, the rolling load is improved useful degree decreases loaded on the respective roller bearing for each column.

[0007]

[Embodiment 1] FIG. 1 is an explanatory view showing a configuration of a mandrel bar for manufacturing a seamless pipe to which one embodiment of the present invention is applied. In the figure, 1
Is a plug mounting portion, which is attached to the tip of a mandrel bar having the same basic structure as the conventional one. Reference numeral 2 denotes a connection portion that fits with the tip of the mandrel bar. Reference numeral 3 denotes an outer cylinder, in which a cylindrical space having a desired depth is formed. Reference numeral 4 denotes a radial bearing, and reference numeral 5 denotes a thrust bearing, both of which are fitted into the internal space of the outer cylinder 3. Reference numeral 6 denotes a rotating shaft which rotates in the outer cylinder 3 via the radial bearing 4 and the thrust bearing 5. Reference numeral 7 denotes a flange portion, which forms a lid in a cylindrical space of the outer cylinder 3. Reference numeral 8 denotes a plug mounting projection, which is integrated with the flange 7. Reference numeral 9 denotes a spacing member for maintaining the radial bearing 4 and the thrust bearing 5 at a desired spacing. 11 is a bearing nut, a radial bearing 4 and a thrust bearing 5
Further, the spacer 9 is pressed toward the flange 7. Also, 12
Is a plug for performing an inner surface finish during drilling and rolling of a material to be rolled.

In the above-described thrust bearing 5, as shown in the detailed view of FIG. 2, both the outer cylinder 3 and the rotary shaft 6 incorporate an annular member having an L-shaped cross section from the surface receiving the thrust load. as two of the wood but facing the opposite direction with a clearance
And the surface receiving the thrust load and the ring
A plurality of thrust bearings provided separately between
The rows of thrust bearings 5a and 5b have the same function as when a load is applied to the same surface. Therefore, the thrust load applied to the thrust bearings 5a and 5b is dispersed and is applied to the bearing rollers 13a and 13b, and the load applied to one of the bearing rollers 13a and 13b is reduced. As a result, the life of the thrust bearing 5 can be greatly extended without changing the dimensions such as enlarging the outer shape, and the failure of the thrust bearing is a bottleneck. Further, by adopting the shape of the above-described embodiment, it is easy to incorporate the mandrel bar into a small diameter mandrel bar. In the above-described embodiment, the case where the thrust bearings are arranged in two rows has been exemplified. However, the present invention is not limited to this, and has another similar function, for example, one to two or more sets. May be changed.

[0009]

As described above, according to the present invention, a mandrel bar excellent in thrust load resistance and capable of withstanding use for a long time can be obtained. By extending the life of the plug mounting portion, the deterioration of peripheral equipment due to the elimination of the whirling state of the mandrel bar is reduced, and the productivity is improved by reducing the stoppage of work for plug replacement.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a configuration of a mandrel bar for seamless pipe manufacturing to which an embodiment of the present invention is applied.

FIG. 2 is a detailed view showing a thrust bearing of a mandrel bar for manufacturing a seamless pipe according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plug mounting part 2 Connection part 3 Outer cylinder 4 Radial bearing 5, 5a, 5b Thrust bearing 6 Rotating shaft 7 Flange 8 Plug mounting protrusion 9 Spacing material 11 Bearing nut 12 Plug 13 Bearing roller

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21B 25/06

Claims (1)

(57) [Claims] The cross section of the tip of the mandrel bar and the plug mounting portion is L-shaped from the surface receiving the thrust load .
The two annular members thus formed are arranged so as to face each other in the opposite direction with a gap, and a surface receiving a thrust load is provided.
And a plurality of thrust bearings separately between the annular members
The multiple thrust bearings are placed and load is applied to the same surface
It has the same function as it did and shares the thrust power
A mandrel bar for seamless pipe manufacturing, wherein the mandrel bar is mounted on a shaft via a double-row thrust bearing configured as described above.