RU2416474C1 - Method of tube screw rolling and mill to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention is intended for increasing quality of hot-rolled weldless tubes from high-strength steels and alloys. Proposed method comprises tube billet heating, piercing it into barrel and rolling into tube in gage formed by working rolls, guide tool and piercing or rolling mandrel fitted on the rod. Barrel pierced, its front end is fed into gage for it to be rolled into tube, gage is readjusted for rolling by replacing the rod with mandrel and fitting said mandrel in gage by moving it axially relative to rolls without varying position of the latter. Proposed stand comprises feeding roll table, cross feed device, working stand with drive, front table with pusher and deflecting roll table. Two-section cross feed device is used, one section being provided with extractor and another one, a reversing overlapping extractor, being arranged parallel to rolling axis and provided with additional section arranged between device sections fitted with stationary stop with appliance to feed lubrication into barrel.

EFFECT: high-quality tubes, simplified design and control system, higher reliability and longer life.

2 cl, 4 dwg

Description

The invention relates to the field of metal forming and relates to a method for producing hot-rolled seamless tubes by screw rolling.

A known method of screw rolling of pipes, the patent of Germany No. 3717698, class. B21B 19/02, claimed 05.26.87, publ. 01/14/88, including heating the billet, piercing the billet into a sleeve and its subsequent rolling into a pipe in the same stand of the helical rolling mill. After flashing on the spherical part of the mandrel, the work rolls, the guiding tool and the drive of the work rolls are retuned. Then the sleeve with the same heating with the rear end is fed into the caliber in the opposite direction to the firmware direction, and rolled out on the cylindrical part of the mandrel.

The main disadvantage of this method of screw rolling pipes is a large loss of heat by the sleeve after flashing. This is due to the fact that as a result of the reconfiguration of the work rolls, the guiding tool and the drive of the work rolls from the firmware to the rolling process, there is a long contact of a large area of the sleeve along the perimeter and length with an unremoved mandrel, which leads to increased energy consumption for the deformation of the cooled sleeve and the difference and reduces the quality of the pipes.

Known mill screw rolling pipes, in which the piercing of the workpiece into the sleeve and its subsequent rolling is carried out in the same working stand, Japan patent No. 63154206, class. B21B 19/06, claimed 12/15/86, publ. 06/27/08, the mill contains a feed roller table, a device for the transverse transfer of workpieces, a work stand with a reversible drive for rotating the rolls, a front table with a pusher, a rear table and a discharge roller table. The front and rear tables of the mill are equipped with two successive sets of equipment, each of which includes centering devices, a stop-adjusting mechanism, issuing rollers, and a device for extracting rods.

The main disadvantage of this mill is the bulkiness of its design, the complexity of the kinematic relationships and the mill control system, caused by the presence of two sets of front and rear table equipment in series, as well as the presence of a reversible roll drive. All this affects the reliability and durability of the mill and its cost.

Of the known methods for screw rolling of pipes, the closest in technical essence is the method of screw rolling described in Russian patent No. 2315671, class. B21B 19/00, claimed 12/06/2006, publ. January 27, 2008

This method includes heating the workpiece, piercing the workpiece into a sleeve and its subsequent rolling into a pipe in the caliber of the stand, formed by work rolls, a guiding tool and a piercing or rolling mandrel placed on the rod. In this case, the cross section of the deformation zone, corresponding to the workpiece entering the rolls during flashing, and the cross section of the deformation zone, corresponding to the beginning of contact deformation of the sleeve between the rollers and the mandrel during rolling, are 0.4–2.6 times the sleeve diameter from each other along the deformation zone. . A batch of blanks is rolled in caliber with a piercing mandrel. Then, in order to maintain the temperature, the resulting sleeves are placed in a thermostat or shielded with heat shields. After rolling the entire batch of workpieces, the work rolls and the caliber guide tool are reconfigured for rolling and the piercing mandrel is replaced with a rolling mandrel. Then the sleeves from the heat-insulating device with the front end are set in this caliber for rolling into the pipe. In this case, firmware and rolling are carried out in predetermined sections of the deformation zone, spaced apart from each other by a certain distance.

A disadvantage of the known method of screw rolling pipes is a gap in the firmware-rolling process, caused by the need for the accumulation of sleeves after flashing and their temperature control. The limited temperature storage time in the thermostat limits the number of sleeves accumulated for rolling, which in practice reaches several pieces and necessitates the adjustment of the mill to rolling. After the rolling process is completed, the mill is again rebuilt to firmware and so on. The presence of a large number of unproductive downtime caused by frequent transitions from one process to another significantly reduces the productivity of the mill.

In addition, the process of flashing and rolling in predetermined sections of the deformation zone, spaced apart by a certain distance, causes a sharp restriction on the assortment of rolled pipes.

Another disadvantage of this method is the presence of a thermally insulating device for sleeves, which increases the cost of the equipment of the mill.

Of the known mills for screw rolling of pipes, the closest in technical essence is the mill described in the patent of Germany No. 3717698, class. B21B 19/02, claimed 05.26.87, publ. 01/14/88

In this screw rolling mill, the billet is pierced into the sleeve and its subsequent rolling into the pipe is carried out in the same working stand. The mill contains a feed roller, a device for the transverse transfer of workpieces, a working stand with a mechanism for changing the position of the rolls between the passages and a reversible drive of the rolls, a front table with a pusher, a rear table and a discharge roller located along the axis of the mill.

The main drawback of the design of this screw rolling mill, as well as previously considered, is the complexity of its design and control system. The presence in the design of the working stand of the mill of an additional multi-link mechanism for changing the position of the work rolls between the passages almost doubles the number of parts, its components, and their connections, which reduces the rigidity of the stand and adversely affects the difference in rolled tubes. The increased difference is also exacerbated by the presence of the previously indicated long contact of a large area of the liner with an unremoved mandrel due to a complex control system caused by the reconfiguration of the work rolls, the guide tool and the drive of the work rolls from the flashing process to the rolling process. The mill control system is also complicated by the presence of a reversible roll rotation drive. As a result of all this, the reliability and durability of the mill are reduced and its cost is increased.

The objective of the present invention is to provide a method for screw rolling of pipes and a mill for its implementation, which allows to obtain high-quality pipes from steels and alloys of a wide brand and size assortment at lower cost for equipment having a simple design and control system and having high reliability and durability.

The problem is achieved in that in the method of screw rolling of pipes, including heating the workpiece, piercing the workpiece into a sleeve and its subsequent rolling into a pipe in caliber formed by work rolls, a guiding tool and a piercing or rolling mandrel placed on the rod, according to the invention, after flashing the sleeve with the same heating, the front end is set into a gauge for rolling into a pipe, and the reconfiguration of the gauge for rolling is carried out by replacing the core with the mandrel and installing the mandrel in the caliber by moving it in tion direction with respect to the rolls without changing their position. In a tube rolling mill for carrying out a method comprising a feed roller, a transverse transfer device, a working stand with a drive, a front table with a pusher, a rear table and a discharge roller, according to the invention, the transverse transfer device is made in two sections, one section of which has an ejector, and the other is a shutter-ejector, while the discharge roller table is made reversible, located parallel to the rolling axis and equipped with a transverse cross located between the sections of the device cottages with an additional section along the length of the front table, equipped with a stationary stop with a means for introducing technological grease into the sleeve.

The production of high-quality pipes from steels and alloys of a wide assortment by the proposed method is achieved by easily reconfiguring the caliber from the firmware to rolling, which is possible by replacing the rod with a piercing mandrel with a rod with a rolling mandrel and installing this mandrel in gauge by moving it in the axial direction relative to the rolls without changing their position, while replacing the rod with the mandrel eliminates the long contact of the rod with a heated sleeve (draft tube). In addition, since in this method of screw rolling, there is no large heat loss of the sleeve after rolling, additional equipment for heating them is not required.

The simplicity of the control system and the design of the screw rolling mill for the implementation of the method is ensured by the possibility of easily reconfiguring the caliber of the stand by replacing the rod with the mandrel, as a result of which the working stand of the mill does not have an additional mechanism for changing the position of the work rolls between passes and is highly rigid and accurate in their installation in the deformation zone . In addition, the transfer of the sleeve (draft tube) to the front table of the mill for subsequent rolling is carried out by means of a special, simple-to-use device for the transverse transmission and the discharge conveyor is reversible with an additional section, as a result of which the use of a reversible drive for rotating high-power rolls is not required . All of the above ensures high reliability and durability of the mill, and also reduces its cost.

To explain the invention, the following is a specific example of the implementation of the rolling mill and describes an example implementation of the method on it, with reference to the accompanying drawings, in which:

figure 1 shows a General view of the rolling mill in plan,

figure 2 shows a diagram of the rolling process in the mill,

figure 3 shows the caliber of the working stand of the mill when flashing the workpiece in the sleeve,

figure 4 is the same when rolling the sleeve into the pipe.

The helical rolling mill of pipes includes a feed roller 1, a device 2 for transverse transmission, a work stand 3 with a drive 4 for firmware and rolling, a front table 5 with a pusher 6, a rear table 7 and a reversing discharge roller 8 located parallel to the rolling axis. The device 2 for the transverse transmission consists of two sections, one of which 9 has an ejector 10 for workpieces, and the other 11 is a blocker-ejector 12 for sleeves (rough pipes). The discharge roller 8 is made reversible, arranged parallel to the rolling axis and provided with an additional section 13 located between sections 9 and 11 of the device 2 for transverse transmission, having a front table length and equipped with a stationary stop 14 with means 15 for introducing the technological lubricant into the sleeve.

The piercing of the heated billet 16 into the sleeve 17 with the front end 18 and its subsequent rolling into the pipe 19 is carried out in gauge 20 of the working stand 3 of the tube rolling mill, formed by work rolls 21, a guide tool 22 and placed on the rod 23 or 24 with piercing 25 or rolled 26 mandrel.

The heated billet 16 along the inlet roller table 1, the device 2 for transverse transmission with the ejector 10 is transferred to the front table 5 of the mill, while the additional section 13 of the outlet roller table 8 is closed for free passage of the billets. Then, with the pusher 6, the workpiece 16 is fed into the caliber 20 of the working stand 3 of the mill for firmware. After flashing, the sleeve (draft tube) without heating with a reversible discharge roller 8 is transferred to an additional section 13 to the stationary stop 14, where technological lubricant is introduced into the sleeve (draft tube) using means 15, and then through section 11 of the device 2 for transverse transmission with the overlap, ejector 12 sleeve (rough pipe) serves on the front table 5 of the rolling mill. At the same time, on the back table 7 of the mill, replace the rod 23 with the piercing mandrel 25 with the rod 24 with the rolling mandrel 26 and set the mandrel 26 along the axis of rolling in the necessary position relative to the rolls 21. Using the pusher 6, the sleeve 17 or the draft tube with the front end 18 with the temperature necessary for rolling is set in the same gauge 20 of the working stand 3, where it is rolled out into the pipe 19 without reconfiguring the work rolls 21 and the guide tool 22.

An example of the method:

When receiving pipes on a helical rolling mill with rolling the sleeve, a billet with a diameter of 180 mm from steel of grade "D", heated to a temperature of 1220 °, is first stitched into a sleeve with a diameter of 172 mm and a wall thickness of 32 mm in the gauge of the working stand of the helical rolling mill. In this case, the stand gauge is formed by two work rolls with a diameter of 750 mm, a barrel length of 600 mm, a feed angle of 12 °, spaced apart in a pinch distance of 157 mm, guiding rulers installed in a plane perpendicular to the axis of the rolls at a distance of 176 mm from each other and fixed on a rod with a diameter of 94 mm, a piercing mandrel with a diameter of 98 mm, the nose of which is extended beyond the pinch of the rolls by a distance of 100 mm. After flashing, the sleeve is transferred to the inlet side of the screw rolling mill. Replace the rod with a piercing mandrel with a rod with a diameter of 116 mm with a rolling mandrel with a diameter of 122 mm and set it along the rolling axis for the pinch rolls at a distance of 115 mm. Then the front end of the sleeve with a temperature of 1180 ° set in the caliber with the same installation parameters of the rolls and rulers and rolled into a pipe with a diameter of 170 mm and a wall thickness of 19 mm.

The proposed method of screw rolling and the mill for its implementation in comparison with the known ones allow to obtain high-quality pipes from steels and alloys of a wide assortment on equipment that has a simple design and control system and has high reliability and durability.

Claims (2)

1. The method of screw rolling of pipes, including heating the workpiece, flashing the workpiece into a sleeve and its subsequent rolling into a pipe in caliber formed by work rolls, a guiding tool and a piercing or rolling mandrel placed on the rod, characterized in that after flashing the sleeve with the same heating the front end is set into a gauge for rolling into a pipe, for which purpose the gauge is reconfigured by replacing the rod with a piercing mandrel with a rod with a rolling mandrel by installing it in caliber by moving to the phenomenon of rolling relative to the work rolls without changing their position. 2. A mill for rolling pipes containing a feed roller, a device for the transverse transfer of workpieces and sleeves, a working stand with a drive, a front table with a pusher, a rear table and a discharge roller, characterized in that it is designed to implement the method according to claim 1, with this device for the transverse transmission is made in two sections, the discharge roller table is made reversible, located parallel to the rolling axis and has an additional section along the front length located between the sections of the device for transverse transmission a table equipped with a stationary stop with a means for introducing technological grease into the sleeve, one section of the device for the transverse transmission has a workpiece ejector, and the other has a shutter-ejector made with the possibility of overlapping an additional section and ejecting the sleeve, the rear table is made with the possibility of replacing the shaft with piercing mandrel on a rod with a rolling mandrel and installing it in caliber by moving in the rolling direction relative to the work rolls.

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