JPH0699206A - Inclining rolling method for seamless steel tube - Google Patents

Abstract

PURPOSE:To efficiently display the burning prevention effect of lubricant, to reduce the cost and time required to repair flaw on the surface of product and decrease the wear of guide shoes at the time of executing piercing rolling of a steel tube while supplying a lubricant for preventing burning to disk roll type guide shoes in an inclined piercing mill. CONSTITUTION:The thickness of lubricating film is measured with thickness gages 8, 8a in the front position in the direction of rotation of the guide shoe to the spraying supply positions of the lubricants 7, 7a to the disk roll type guide shoes 2, 2a, signal for adjusting the supply of lubricant is sent to lubricant supply adjusting devices 10, 10a in accordance with the measured thickness of lubricating film and the measured thickness of lubricating film is made to fall in proper range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for piercing and rolling a seamless steel pipe using inclined rolls.

[0002]

2. Description of the Related Art For piercing and rolling a seamless steel pipe by a Mannesmann type piercing machine, as shown in FIGS. 2 and 3, a material 5 to be rolled is formed by a pair of inclined rolls 1, 1a and a plug 3 which face each other.
Is to be rolled. The expansion of the outer diameter of the material 5 to be rolled by rolling is regulated by a pair of guide shoes. In recent years, disc roll type guide shoes 2 and 2a as shown in FIG. 2 have been applied to the guide shoes.

In the circumferential direction of the material to be rolled, the surfaces of the guide shoes 2 and 2a are in a condition of sliding with the material 5 to be rolled. In addition, since the rolling reaction force of the guide shoes 2 and 2a for preventing the outer diameter of the rolled material 5 from bulging is large, it is particularly
When rolling high alloy steel represented by% Cr steel, 22% Cr steel and stainless steel, the material to be rolled is likely to seize on the surface of the guide shoes 2, 2a.

As a measure for preventing such seizure, a method of rolling while supplying a graphite-based lubricant to the surface of the guide shoe, as disclosed in JP-A-60-56406, is disclosed in JP-A-2-30311. As shown in (1), there is a technique of supplying a boric acid-based lubricant to the surface of the guide shoe, forming a lubricating film, and then rolling. In all of these techniques, as shown in FIG. 3, the lubricant is spray-injected onto the surfaces of the guide shoes 2, 2a by spray nozzles 6, 6a.

[0005]

However, any of the lubrication methods has the following problems. If the supply amount of the lubricant is too small, the seizure prevention effect cannot be sufficiently obtained, and flaws are left on the surface of the product pipe. On the other hand, if the amount of lubricant supplied is too large, especially when a graphite-based lubricant as disclosed in Japanese Patent Laid-Open No. 60-56406 is used, the surplus lubricant is excessive and the rolled material 5 and roll 1, It is introduced between 1a and lowers the friction coefficient of this portion, causing rolling failure due to slip. Further, when a lubricant film-forming type lubricant as disclosed in JP-A-2-30311 is used, it is difficult to form a film due to a large amount of water, or the lubricant is washed out, so that an anti-seizure effect can be obtained. Sometimes you can't get it. The main causes of these fluctuations in the lubricant supply amount are seasonal fluctuations in the lubricant viscosity due to differences in the outside air temperature during summer and winter, poor maintenance of the piping system, and disturbance due to cooling water such as rolls.

If the above-mentioned lubricant can be effectively used, in addition to the prevention of seizure, there is an advantage that the amount of wear of the guide shoes can be reduced not only during rolling of high alloy steel but also during rolling of ordinary steel. . Therefore, an object of the present invention is to provide a method for efficiently performing lubrication rolling for preventing seizure of a guide shoe of a piercer.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, when a steel pipe is pierced and rolled while a lubricant for the purpose of preventing seizure is supplied to a disc roll type guide shoe in an inclined piercing machine, This is a method for inclined rolling of a seamless steel pipe, characterized in that the thickness of the coating film formed on the guide shoe surface is measured and rolling is performed while adjusting the amount of lubricant supplied based on the measured value.

[0008]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a flow sheet showing a rolling method according to the present invention. The spray nozzle 6 is attached to the guide shoes 2, 2a.
Lubricants 7 and 7a are sprayed from 6a. Lubricant 7,
7a is supplied from the lubricant storage tank 12 by the pumps 11 and 11a via the filters 14 and 14a. 13 is a stirrer. The thickness of the lubricating coating is measured by the thickness gauges 8 and 8a at the position in front of the guide shoes 2 and 2a in the rotation direction with respect to the injection supply position of the lubricant 7 and 7a to the disc roll type guide shoes 2 and 2a.

A thicker lubricating coating is required during rolling of high alloy steel than during rolling of ordinary steel. Further, when rolling to a thin-walled pipe, a thicker lubricating coating is required than when rolling to a thick-walled pipe. As described above, since the appropriate lubricating film thickness differs depending on the target rolled steel type and rolling conditions, the appropriate thickness range is grasped in advance, and the numerical value is used as the lubricant supply amount setting change calculation device 9,
Input to the database of 9a.

If the thickness of the lubricating coating measured during rolling is out of the proper thickness range, the following processing is performed. (A) When the measured lubricating coating thickness is thicker than the proper thickness range, a signal for reducing the lubricant feeding amount is sent to the lubricant feeding amount adjusting devices 10 and 10a, and the measured lubricating coating thickness is reduced to be in the proper range. Fit in. (B) On the other hand, when the measured thickness of the lubricating coating is smaller than the proper thickness range, a signal for increasing the lubricant supply amount is sent to the lubricant supply amount adjusting devices 10, 10a. If the measured thickness of the lubricating coating shows an increasing tendency, this treatment is continued and the thickness is kept within an appropriate range. If the measured thickness of the lubricating coating does not show an increase tendency, it is determined that the coating is defective due to excessive supply of the lubricant. Therefore, a signal for reducing the lubricant supply amount is sent to the lubricant supply amount adjusting devices 10 and 10a to measure the thickness. Keep the lubricating film thickness within the appropriate range.

By controlling the lubricant supply amount as described above, the lubricating coating on the surface of the disc shoe can be controlled within an appropriate thickness range, and the effect of preventing seizure by the lubricant and the effect of reducing guide shoe wear can be effectively obtained.

[0012]

EXAMPLES The present invention was applied to rolling 5000 billets having diameters of 175 mm and 210 mm. Of which, 1% Cr
The number of rolled high-alloy steel billets higher than steel is 500. For guide shoe lubrication, alkanolamine borate 15wt%, styrene-acrylic emulsion 10w
An aqueous solution containing t% was spray-supplied to each guide shoe.

The thickness of the lubricating coating was measured on the surface of the disk type guide shoe having a diameter of 1350 mm at a position approximately 1770 mm in front of the lubricant supplying position in the rotational direction of the guide shoe. Infrared absorption type non-contact type thickness gauges 8 and 8a were used to measure the thickness of the lubricating coating. For comparison, the same number of billets was rolled by the same lubrication rolling without measuring the thickness of the lubricating coating according to the present invention.

If the lubrication does not function effectively, seizure will occur on the disc type guide shoe. The occurrence of shoe mark flaws on the product surface resulting from this is shown in Table 1 in comparison with the conventional rolling method and the present invention. Also, the wear amount of the guide shoes is shown in the same table in comparison with the conventional rolling method and the present invention. By carrying out the present invention, the frequency of occurrence of shoe mark defects is reduced by 75 to 80% as compared with the prior art. Also, the wear amount of the guide shoes was reduced by 12.5-33.3%.

In this embodiment, an infrared absorption type thickness gauge was used as the lubricating coating thickness gauge, but similar effects can be expected not only with other non-contact type thickness gauges, but also with contact type thickness gauges. .

[0016]

[Table 1]

[0017]

According to the present invention, when the lubricant for preventing seizure of the guide shoe is applied at the time of piercing and rolling with the piercer, the seizure preventing effect of the lubricant can be efficiently exhibited. You can now reduce the cost and time required to repair the defect. At the same time, the effect of reducing the amount of wear of the guide shoe by the application of lubricant was obtained, and the amount of tool wear was also reduced.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a disc type guide shoe lubrication rolling method according to the present invention.

FIG. 2 is a schematic view of a Mannesmann puncher.

FIG. 3 is a schematic diagram of billet piercing and rolling by a Mannesmann piercing machine.

FIG. 4 is a schematic view of a conventional disc type guide shoe lubrication rolling technique.

[Explanation of symbols]

 1, 1a Roll 2, 2a Guide shoe 3 Plug 4 Bar 5 Rolled material 6, 6a Spray nozzle 7, 7a Lubricant 8, 8a Thickness gauge 9, 9a Lubricant supply amount setting change calculation device 10, 10a Lubricant supply amount Adjustment device 11, 11a Lubricant supply pump 12 Lubricant storage tank 13 In-tank agitator 14, 14a Filter

Claims (1)

[Claims] 1. The thickness of the coating film formed on the guide shoe surface by the lubricant when the steel pipe is pierced and rolled by supplying an anti-seizure lubricant to the disc roll type guide shoe with an inclined punching machine. Then, the method for tilt rolling of a seamless steel pipe is characterized in that rolling is performed while adjusting the supply amount of the lubricant based on the measured value.