RU2185910C1 - Mill for making straight-seam welded measure-length tubes - Google Patents

Abstract

FIELD: welded tube production, possibly by argon-arc microplasma welding. SUBSTANCE: mill includes apparatus for separating tube mounted in front of sizing stand. The last may operate in accelerated mode for periodic feed of tubes and it is provided with pickup for detecting tube motion value. After welding tube, sizing stand is periodically energized for feeding predetermined-length piece of tube for separating it. At time moment of separation of tube by measured lengths, tube is reliably hold by means of rolls against turning and shifting. It allows to omit additional mechanisms, to shorten length of mill and to simplify automatization of process for making welded tubes with accurate size of length. EFFECT: enhanced quality of welded tubes, simplified design of mill and reduced size of the whole line. 2 dwg

Description

 The invention relates to pipe welding production and can be used for welding pipes used in various engineering industries.

 A known mill for forming and welding longitudinal pipes, comprising a molding device, a mechanism for adjusting the position of the edges of the workpiece, a welding device, a pulling calibration stand and an associated device for cutting pipes along the welding path [A.c. SSCP 1197755, MKI 4 B 21 C 37/08 1985].

 The disadvantage of this mill is due to the low quality of welding, since the need for reciprocating movement of the cutting device, which has a complex kinematic connection with the pulling cage to synchronize the movement, leads to undesirable interference (vibrations, jerks, etc.) that affect the rather sensitive process of microplasma welding of thin-walled pipes (with a wall thickness of 0.3 ... 1 mm). In addition, for the production of pipes from sheets (strips) limited in length, this mill is generally unsuitable.

 The closest in technical essence and the achieved effect is a production line for the production of electric welded pipes, containing a strip preparation section, a pipe forming section, a welding unit, a calibration mill and a device for dividing the pipe into measured lengths, made in the form of flying scissors for preliminary cross cutting of the strip simultaneously on both sides, as well as multi-roll and additional stands [A.S. USSR 538756, MKI 4 B 21 C 37/08, 1976].

 However, the known production line is characterized by operation at high welding speeds for the manufacture of pipes of relatively large lengths (5 ... 10 m). In this case, the pitch of the notches on the strip exceeds the length of the molding device, and the notches themselves do not have any pronounced negative effect on the process of folding the strip into the pipe. And, on the contrary, in the production of short pipes (0.5 ... 1 m) with often alternating cuts, the latter do not allow due to the tension of the edges during the convolution of the strip to produce high-quality molding of the pipe, since the pipe is folded with distorted edges, which affects further welding process. At the same time, in the manufacture of short stainless steel tubes up to 1 mm thick, argon-arc microplasma welding with low speeds (up to 5 m / min) is widely used, which ensures the best quality of the weld. To obtain high-quality welding of such pipes, the stable position of the converging edges before welding and the absence of corrugations on them are very essential. The known production line for the above reasons is not able to ensure the manufacture of short and accurate along the length of the pipes by microplasma welding. In addition, the presence of an additional stand and a drive multi-roll stand far removed from it complicates the equipment and increases the long dimensions of the production line.

 The objective of the invention is the creation of a small-sized mill, providing the manufacture, in addition, short and accurate along the length of thin-walled pipes mainly by the method of argon-arc microplasma welding. At the same time, a significant simplification of the entire mill design is important. Another objective of the invention, associated with the previous one, is the automation of the separation of the pipe into measured lengths in the process of its retention and synchronized movement in the calibration stand after leaving the welding device.

 The problem is solved in that in a mill for the manufacture of longitudinal welded pipes of measured length, containing a strip preparation section, a molding device, a welding device, a calibration stand and a device for dividing the pipe into measured lengths, in contrast to the prototype, a pipe separation device is installed between the welding device and a calibration stand, the latter being configured to operate in reverse mode to perform the additional function of accelerated periodic feeding and holding pipes in its division.

 Separation of the pipe is possible into short measured lengths and is carried out with the pipe already welded, which does not affect the quality of welding and increases the accuracy of cutting along the length. The location of the device for separating the pipe between the welding device and the calibration stand, as well as the reversal of the pipe, create without previously complicating the structure the previously unknown prerequisites for this possibility, and the separation of the pipe is feasible simultaneously with the molding and welding of the subsequent pipe. The role of the pipe holding mechanism during its separation is performed by the same calibration stand. This allows, unlike the prototype, to eliminate the presence of additional stands and reduce the length of the mill. The absence of negative factors affecting the quality of pipe molding and welding allows the use of microplasma argon-arc welding and the manufacture of thin-walled pipes of high accuracy and quality. In a preferred embodiment, it is contemplated that a sensor is included in the calibration stand. This, in turn, makes it possible to program the dimensions of the lengths to be separated and to control operation modes in order to automate the entire mill.

 Figure 1 shows a plan view of the proposed mill; figure 2 - diagram of the sequential shaping of the pipe and the actuation of the aggregates of the line.

 The mill contains a strip preparation section 1 (Fig. 1), a molding device 2, a welding device 3, a calibration stand 4 and a device for dividing the pipe into measured lengths 5. The device for dividing the pipe 5 can have any known design (cutting mill, spindle cutting a head with cutting discs, a plasma torch, etc.), allowing for quick separation of the pipe with a cutting tool 6 (Fig.2). The calibration stand 4 is located close to the cutting tool 6. To allow the pipe to be pulled, the distance between the molding device 2 and the calibration stand 4 should be slightly less than the length of the pipe 7 welded from the strip-blank 8. The calibration stand 4 is configured to perform an additional function of periodic feeding and holding the pipe during its separation, because its rolls 9 are able to rotate independently of the rolls of the molding device. To automate the operation of the line, the calibration stand 4 is equipped with a sensor 10 for measuring the length of the pipe 7 connected to the non-driven measuring roller 11. The readings of the sensor 10 are continuously supplied to the line control system (not shown) and determine the operating modes of the calibration stand 4, as well as a device for separating the pipe 5 . In the feed mode of the pipe, the calibration stand can be turned on to operate at a higher speed of movement of the pipe 7.

 The mill works as follows. After preparation and orientation in the input wiring of the strip-blank 8, it enters the molding device 2 and then into the welding device 3, where it is transformed into a pipe 7 (Fig. 2a). In the future, the pipe 7 is captured by the drive rolls 9 of the calibration stand 4 (Fig. 2b) and is pulled out of the welding zone, while the sensor 10 starts counting the length of the pipe being moved and enters the obtained values into the control system. At the time of the exit of the pipe from the welding device 3, registered by the sensor 10 according to the size of the pipe segment passed, the calibration stand 4 switches to the pipe moving mode at a higher speed to feed in accordance with the set value of the measured length to be separated (Fig.2c). After that, the calibration stand 4 is stopped and the device for separating the pipe 5 is turned on (Fig. 2d). When this rolls 9 reliably hold the pipe from rotation and displacement. In the future, by periodically turning the calibration stand 4 and the device for separating the pipe 5 on and off, the remaining pipe is divided into predetermined long sections 12, the latter having high accuracy, since this operation is performed on a stationary pipe. Detachable pipe segments can vary in length, since the control system allows you to set their values using the length dial from the control panel (not shown). Detachable pipe sections 12 fall into the container 13. The mill allows the launch of a new strip 8 and welding of the subsequent pipe simultaneously with the rapid separation of the previous pipe into measured lengths, as shown above. The scheme of the mill provides an increase in the quality of the shape of the pipe, since each pipe is calibrated twice.

 Using the proposed mill will allow the manufacture of short pipes with higher separation accuracy, improve the quality of molding, welding and calibration, as well as simplify the design and reduce the overall dimensions of the entire line.

Claims (1)

 A mill for manufacturing longitudinal welded pipes of measured length, comprising a strip preparation section, a molding device, a welding device, a calibration stand and a device for dividing the pipe into measured lengths, characterized in that a device for dividing the pipe into measured lengths is installed between the welding device and the calibration stand, while the latter is made with the possibility of working in reverse mode to implement an additional function of accelerated periodic supply and retention of the pipe when it is separated.

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