JPH07178422A - Mandrel bar for manufacturing seamless tube - Google Patents

Abstract

PURPOSE:To obtain a mandrel bar which is excellent in resistance to thrust load and withstands use for long time by pivotaly supporting the tip of the mandrel bar and plug mounting part with a double-row test bearing. CONSTITUTION:By incorporating an annular material whose cross, section is made into an L-shape from a face with which thrust load is received into either of an outer cylinder 3 and rotary shaft 6, the thrust bearing 5 is imparted with the function equivalent to two rows of the thrust bearings 5a, 5b are loaded on the same surface. Thrust load added to the thrust bearings on two places is dispersed, falls on two pairs of bearing rollers 13a, 13b and the load loaded on either one of the bearing rollers is reduced. Consequently the life of the thrust bearing 5 is remarkably prolonged without executing size change such as the enlargement of external size and it is dissolved that breakage of the thrust bearing 5 is a bottleneck. In this way, by prolonging the life of the plug mounting part, the centrifugal whirling state of the mandrel bar is eliminated, the deterioration of peripheral equipment is reduced and productivity is improved.

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 producing a seamless pipe, and more particularly to a plug mounting portion thereof.

[0002]

2. Description of the Related Art Perforations used in a seamless tube manufacturing method using the Mannesmann plug system, and perforation plugs of an inclined rolling mill used in each rolling process, and rolling plugs are fed between piercing or rolling rolls. Rotational force is applied from the rolled material that is inclined and rolled. At that time, in order to improve the dimensional accuracy of the material to be rolled, the mandrel bar is pivotally attached to the tip of the mandrel bar. As a bearing structure therefor, for example, there is one described in Japanese Utility Model Laid-Open No. 4-22101.

[0003]

In the conventional mandrel bar for producing a seamless pipe as described above, since the plug can be rotated, compared with the type in which the entire bar is rotated, the material to be rolled is The purpose of improving the dimensional accuracy and / or the durability of the plug has been achieved. But,
Since the outer diameter of the mandrel bar is determined by the size of the material to be rolled, the size of the bearing is also limited.
As a result, the rolling reaction force is 80
Since the load is up to 100 Ton, the load on the thrust bearing is excessive and the impact is large, and further improvement has been demanded in order to prolong the service life.

The present invention has been made to solve the above problems, and improves the dimensional accuracy of the material to be rolled without the need for a bearing having special performance.
The purpose of the present invention is to obtain a mandrel bar for producing seamless pipes, which can be expected to improve productivity because the durability of bearings can be extended.

[0005]

In the mandrel bar for producing a seamless pipe according to the present invention, the tip of the mandrel bar and the plug mounting portion are axially mounted via a double row thrust bearing.

[0006]

In the present invention, since the tip of the mandrel bar and the plug mounting portion are axially mounted via the double row thrust bearing, the rolling load applied to each bearing roller in each row is reduced. Durability is improved.

[0007]

【Example】

Example 1. FIG. 1 is an explanatory view showing the configuration of a seamless pipe manufacturing mandrel bar to which an embodiment of the present invention is applied. In the figure, reference numeral 1 denotes 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 connecting portion that fits with the tip of the mandrel bar. An outer cylinder 3 has a cylindrical space having a desired depth formed therein. Reference numeral 4 is a radial bearing, and 5 is a thrust bearing, both of which are fitted into the inner space of the outer cylinder 3. Reference numeral 6 denotes a rotary shaft, which rotates in the outer cylinder 3 via the radial bearing 4 and the thrust bearing 5. Reference numeral 7 denotes a collar portion, which forms a lid state in the cylindrical space of the outer cylinder 3. Reference numeral 8 is a plug mounting projection, which is integrated with the flange 7. Numeral 9 is a spacing member for maintaining the radial bearing 4 and the thrust bearing roller 5 at a desired spacing. Reference numeral 11 denotes a bearing nut, which presses the radial bearing 4, the thrust bearing 5, and the spacer 9 toward the collar portion 7. Further, reference numeral 12 is a plug for finishing the inner surface during perforation and rolling of the material to be rolled.

In the thrust bearing 5, as shown in the detailed view of FIG. 2, both the outer cylinder 3 and the rotary shaft 6 are assembled with an annular member having an L-shaped cross section from the surface receiving the thrust load, and are arranged in two rows. The thrust bearings 5a and 5b have the same function as that when a load is applied to the same surface. Therefore, the thrust load applied to the thrust bearings 5a and 5b is dispersed, and the bearing rollers 13a and 13b are dispersed.
Therefore, 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 destruction of the thrust bearing is a bottleneck. Further, by adopting the shape of the above-mentioned embodiment, it becomes easy to incorporate the mandrel bar having a small diameter size. In addition, in the above-mentioned embodiment, the case where the thrust bearings are arranged in two rows has been illustrated, but the present invention is not limited to this, and those having other similar functions, for example, two rows to three rows or more. May be changed to a plurality of rows, or a design change such as one set to a large number of two or more sets.

[0009]

As described above, according to the present invention, since a mandrel bar having excellent thrust load resistance and capable of withstanding long-term use can be obtained, it is possible to improve the dimensional accuracy of reducing the uneven thickness of the rolled material. By extending the life of the plug mounting portion, deterioration of peripheral equipment due to elimination of whirling state of the mandrel bar is reduced, and work stoppage for plug replacement is reduced, thereby improving productivity.

[Brief description of drawings]

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

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A mandrel bar for producing a seamless pipe, wherein a tip of the mandrel bar and a plug mounting portion are axially mounted via a double-row thrust bearing.