JP6102854B2 - Pusher drive device and drive method for applying back pressure to billet - Google Patents

Description

  The present invention is a pusher driving device that is installed in a piercer among a series of facilities for producing a seamless steel pipe, and applies a back pressure to a billet to be caught between a pair of inclined rolling rolls, And a pusher driving method.

  When producing a seamless steel pipe, a solid round bar steel (so-called billet) is heated in a heating furnace and then pierced and rolled with a piercer. The piercer has a pair of inclined rolling rolls, and advances and rotates the billet between the inclined rolling rolls. A plug is disposed in the traveling direction of the billet, and the central axis of the plug coincides with the central axis (that is, the rotation axis) of the billet. As the billet advances while rotating in this way, the central portion thereof is perforated by the plug.

  Therefore, in piercing and rolling, it is necessary to smoothly rotate and advance the billet between inclined rolling rolls. However, the reaction force generated when the plug perforates the center portion of the billet becomes a factor that hinders the rotation and progression of the billet. In order to solve this problem, a pusher is installed on the piercer, and piercing and rolling is performed while applying a back pressure to the billet between a pair of inclined rolling rolls. Hereinafter, the pressure applied by the pusher to the billet in order to apply the back pressure to the billet is referred to as the applied pressure, and the speed at which the pusher advances the billet is referred to as the back pressure speed.

  In such piercing and rolling, if the pusher pressing force and back pressure speed are not properly set with respect to the rotation speed, traveling speed and reaction force of the billet, wrinkles are generated on the inner surface of the pierced tube material, or Problems such as equipment failure of piercers and pushers occur. Moreover, in piercing and rolling, the rotation speed, travel speed, and reaction force of the billet fluctuate, and it is necessary to appropriately adjust the pressure and back pressure speed of the pusher following the fluctuation.

  Therefore, various techniques have been studied in order to stably bite the billet into the inclined rolling roll (for example, Patent Documents 1 and 2). However, since the conventional pusher uses a hydraulic cylinder as a driving force source, it takes a long time to change the pressure force and back pressure speed of the pusher. As a result, there is a problem that it is impossible to follow fluctuations in the rotation speed, travel speed, and reaction force of the billet generated during piercing and rolling, and it is not always possible to prevent the failure of the inner surface flaw of the pipe material or equipment.

JP 2001-58207 A Japanese Patent No. 5098477

  The present invention eliminates the problems of the prior art, and stably bites the billet between the inclined rolling rolls while adjusting the pressure and back pressure speed of the pusher during piercing rolling in the piercer. It is an object of the present invention to provide a pusher drive device and a pusher drive method that can prevent the failure of an inner surface flaw of pipe material and equipment.

  The inventor investigated the fluctuation of the rolling load caused by billet piercing because the rolling load acting on the inclined rolling roll has a great influence on the rotation speed, traveling speed and reaction force of the billet in piercing rolling. And it discovered that a rolling load became large when the front-end | tip part of a billet bites, and a rolling load falls in the center part and rear-end part of a billet. Therefore, a control technique capable of changing the pressure and back pressure speed of the pusher in accordance with the fluctuations in the rolling speed and rolling load at the front end, the center, and the rear end of the billet was examined in detail. As a result, an inverter motor is used as a driving force source for the pusher, and the torque control and the rotational speed control of the inverter motor are performed to follow the fluctuation of the rolling load generated during the drilling of one billet. It was found that it is possible to change the pressure and back pressure rate.

  The present invention has been made based on such findings.

  That is, the present invention is a pusher that is installed in a piercer that performs piercing and rolling of a billet in a seamless steel pipe production line and applies back pressure to the billet between a pair of inclined rolling rolls of the piercer. The pusher drive device is equipped with an inverter motor as the drive force source for the pusher, the pressure applied by the pusher to the billet is 7.5 MPa at maximum, and the back pressure speed is 0.5 m / second at maximum.

The pusher drive device of the present invention includes a sensor that is disposed on the entrance side of the piercer and detects the tip of the billet that is pushed in by the pusher, a timer that measures an elapsed time after the sensor detects the billet, and a timer a control unit for elapsed time to change the pressure and pushing speed upon reaching a predetermined value, Ru comprising a.

The present invention relates to a driving dynamic method pusher for bitten by adding back pressure to the billet between the inclined rolling rolls of a pair of piercer for performing the piercing and rolling the billet in seamless steel pipe production line, inverter This is a pusher drive method in which a pusher is driven using a motor and a back pressure is applied to the billet at a pressure of 7.5 MPa or less and a back pressure speed of 0.5 m / second or less.

In the driving method of the pusher of the present invention, the pressure and the following P _S 7.5 MPa at which to bitten the billet to drive the pusher, and the back圧速degree the following V _S 1.0 m / sec, the entry side After a predetermined time has passed after the sensor arranged at the sensor detects the billet tip, the pressure is changed to P _N of 7.5 MPa or less, and the back pressure speed is changed to V _N of 1.0 m / sec or less. We want to change.

  According to the present invention, it is possible to apply a back pressure to the billet between the inclined rolling rolls of the piercer so that the billet can be stably bitten. As a result, it is possible to prevent failure of the inner surface flaw and equipment of the pipe material. Has an exceptional effect.

It is a top view which shows typically the example of the piercer to which this invention is applied.

  FIG. 1 is a plan view schematically showing an example of a piercer to which the present invention is applied. The piercer is provided with a pair of inclined rolling rolls 3, and the plug 1 is supported between the inclined rolling rolls 3 via plug bars 2. Hereinafter, the side on which the pusher 5 is disposed is referred to as the entrance side of the piercer.

  The billet 4 heated in a heating furnace (not shown) is conveyed to the entrance side of the piercer. Then, piercing and rolling is performed while applying back pressure to the billet 4 using the pusher 5, but if the pressure and back pressure speed applied by the pusher 5 to the billet 4 are too large, the rolling load acting on the inclined rolling roll 3 is increased. It increases, and the equipment failure of the piercer is likely to occur. Therefore, the pressure of the pusher 5 is 7.5 MPa or less, and the back pressure speed is 1.0 m / second or less. On the other hand, if the pressure force of the pusher 5 is less than 1.0 MPa and the back pressure speed is less than 0.1 m / sec, the effect of the pusher 5 that stably maintains the rotation and progress of the billet 4 cannot be obtained, and the inner surface of the pipe member Is likely to occur. Therefore, it is preferable that the pressure of the pusher 5 is 1.0 to 7.5 MPa, and the back pressure speed is 0.1 to 1.0 m / second.

  In the piercing rolling of Piercer, the rolling load acting on the inclined rolling roll 3 varies in a short time. For example, it is known that the rolling load increases when the front end portion of the billet 4 bites and the rear end portion comes out, and the rolling load decreases at the center portion of the billet 4. The inverter motor 6 is used as a driving force source for the pusher 5 in order to smoothly follow the pressure and back pressure speed of the pusher 5 against such frequent fluctuations in rolling load.

  If the inverter motor 6 is used, torque control and rotation speed control can be easily performed. That is, the pressure applied by the pusher 5 can be properly maintained by torque control, and the back pressure speed of the pusher 5 can be properly maintained by rotation speed control.

Then, the billet 4 is caught between the inclined rolling rolls 3 with the pressure P _S (MPa) being 1.0 ≦ P _S ≦ 7.5 and the back pressure speed V _S (m / sec) being 0.1 ≦ V _S ≦ 1.0.

  A sensor 7 is disposed on the entrance side of the piercer and detects the tip of the billet 4 pushed by the pusher 5. Since the billet 4 is heated in a heating furnace and has a high temperature, it is preferable to use a non-contact type detection means such as an HMD (Hot Metal Detector) as the sensor 7.

After the sensor 7 detects the tip of the billet 4, the elapsed time is measured with a timer (not shown). When a predetermined time has elapsed, the pressure is changed to P _N (MPa) and the back pressure speed V _N (m / sec). The reason is that the rolling load increases when the front end portion of the billet 4 bites and the rear end portion comes out, and the rolling load decreases at the center portion of the billet 4. In the present invention, since the inverter motor 6 is used as the driving force source of the pusher 5, the pressure and the back pressure speed can be changed in a short time during piercing and rolling. Here, the applied pressure P _N (MPa) is 1.0 ≦ P _N ≦ 7.5, and the back pressure velocity V _N (m / sec) is 0.1 ≦ V _N ≦ 0.5.

The set pressures P _S and P _N and back pressure speeds V _S and V _N and the time from the detection of the billet 4 tip to the change of the applied pressure and back pressure speed depend on the billet 4 steel type and dimensions, etc. Set as appropriate.

  Control means (not shown) for changing the applied pressure and the back pressure speed includes means for storing various data, means for calculating, means for transmitting and receiving, and the like.

  The billet 4 can be applied to both billets manufactured by continuous casting and billets manufactured by split rolling.

  A billet (outer diameter 210 mm, direct cast material) having a Cr content of 13% by mass (so-called 13Cr equivalent) was heated in a heating furnace, and then pierced and rolled using the piercer shown in FIG. The piercing and rolling procedure will be described.

When the billet 4 is pushed between the inclined rolling rolls 3, the pusher 5 is driven by the inverter motor 6, the pressure is set to P _S = 2.0 MPa, the back pressure speed is set to V _S = 0.4 m / sec, and the billet 4 is bitten. I didn't.

An HMD was used as the sensor 7, and after 1.0 second had elapsed after detecting the biting of the roll 3, the pressure was changed to P _N = 3.0 MPa and the back pressure speed was changed to V _N = 0.2 m / sec.

  The rolling load acting on the inclined rolling roll 3 was measured while performing piercing and rolling in this manner. As a result, an excessive increase in rolling load was not recognized from the front end portion of the billet 4 to the center portion and the rear end portion, and the level did not increase to cause equipment failure.

  Furthermore, when the pipe material perforated by the piercer was fed to the subsequent steps (for example, mandrel mill, reducer, etc.) and the inner surface of the obtained seamless steel pipe was visually observed, a reduction in wrinkles was confirmed.

1 plug 2 plug bar 3 inclined rolling roll 4 billet 5 pusher 6 inverter motor 7 sensor

Claims (2)

A pusher installed in a piercer for piercing and rolling a billet in a seamless steel pipe production line, and applying back pressure to the billet between a pair of inclined rolling rolls of the piercer so that the billet is engaged. In the pusher drive device comprising an inverter motor as a driving force source, the pressure applied by the pusher to the billet is 7.5 MPa at the maximum, and the back pressure speed is 1.0 m / sec at the maximum.
A sensor that is disposed on the entrance side of the piercer and detects a tip of the billet that is pushed by the pusher, a timer that measures an elapsed time after the sensor detects the billet, and the progress measured by the timer time drive characteristics and to pulp Fischer that and a control means for changing the the pressure the pushing speed upon reaching a predetermined value. A pusher driving method for applying back pressure to a billet between a pair of inclined rolling rolls of a piercer performing piercing and rolling of a billet in a seamless steel pipe production line, wherein the billet is engaged using an inverter motor. In the driving method of the pusher that drives the pusher and applies the back pressure to the billet at a pressure of 7.5 MPa or less and a back pressure speed of 1.0 m / sec or less,
By driving the pusher and P _S of the pressure 7.5MPa or less when that caught the billet, and the back圧速degree the following V _S 1.0 m / sec, sensor wherein arranged on the entry side When a predetermined time has elapsed after detecting the tip of the billet, the pressure is changed to P _N of 7.5 MPa or less, and the back pressure speed is changed to V _N of 1.0 m / sec or less. the driving method of Help Fischer.

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