RU2278769C2 - Tube thermal cutting apparatus - Google Patents

Abstract

FIELD: thermal cutting of large-diameter tubes in tube welding aggregates, possibly plasma cutting off ends of non-rotary large-diameter tubes and cutting heavy cut-off end portions by pieces suitable for handling, transporting and recovering.

SUBSTANCE: apparatus for thermal cutting of tubes includes base; car moving on rails mounted in base and having pair of drive running wheels mounted on shafts, strut secured to car, car motion drive unit. Cutter is mounted with possibility of changing its position on said strut. Car is also provided with pinion mounted in cantilevers of shafts of pair of running wheels at their outer side; said pinions engage with toothed racks secured to base in parallel to rails. Diameter of pitch circle of pinions is equal to outer diameter of drive running wheels.

EFFECT: improved quality of cutting due to enhanced stability of lengthwise cutting process and due to accurately positioning car carrying cutter relative to tube axis.

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Description

The invention relates to the field of pipe production, and more specifically to thermal cutting of large diameter pipes on pipe welding units, and can be most effectively used for plasma cutting the ends of fixed large diameter pipes and cutting heavy cut ends into parts convenient for cleaning, transportation and disposal.

The large diameter of the pipes (1020-1620 mm) and a significant thickness (up to 50 mm) place higher demands on the plasma cutting device for the stability of the cutting process and the geometric accuracy of the machined surfaces.

A known installation for thermal trimming the ends of pipes of large diameter, containing a base that moves along a trolley mounted on the base of the rails with a cutter mounted on it with the possibility of changing position (ed. Certificate of the USSR No. 1180198, 23 K 7/04, decl. 17.05.84 published on September 23, 85).

A gas or plasma cutter is mounted on a hollow rotating spindle mounted on bearings in a vertically movable cushion mounted on a trolley. The cart along the axis of the processed pipe is moved by means of a rod of a hydraulic or pneumatic pusher interacting with a stop provided on the cart.

The disadvantage of this device for thermal cutting is the insufficiently accurate installation of the torch in the place of the cut and unstable longitudinal cut, since the longitudinal feed of the cutter is carried out using a hydraulic or pneumatic cylinder, which does not provide stability of the speed of movement of the torch during cutting, and, for example, during plasma cutting the deviation from the nominal speed of the plasma torch during the cutting process should not exceed 2%. A hydraulic cylinder with its control equipment can provide a speed accuracy of at least 10%, which is unacceptable during plasma cutting, since the stability of the metal cutting process with a plasma cutter is impaired, and uncut metal sections may appear.

Another disadvantage of this device is a significant kosin cut off the end of the pipe. This is due to the fact that the flanges of the running wheels of the trolley are installed on the guide rails with a guaranteed mounting gap, and when the trolley moves by the size of this gap, it uncontrollably warps relative to the axis of the pipe being processed. When processing large diameter pipes, this leads to an increase in the absolute value of the braid at the pipe end, which ultimately leads to an increase in metal waste during further mechanical processing of the pipe end.

A device for cutting ends of large diameter pipes is also known, comprising a base mounted on the base and moving relative to its movable trolley with a holder fixed to it, on which a cutter is mounted with a possibility of changing position (US Pat. No. 4,729,502, class 228-13, claimed. 12.24.86, publ. 8.03.88 g.).

The drive of the trolley moving along the guides of the base is made in the form of a rack and pinion gear mounted on the trolley, the gears of which are mounted on a shaft connected to the hydraulic cylinder rod. This drive allows you to double the speed of movement of the cart compared to the speed of movement of the rod of the hydraulic cylinder, usually not exceeding 0.5 m / s.

The disadvantage of this device for cutting pipes is the insufficiently accurate installation of the torch in the place of cut and an unstable longitudinal cut, since a hydraulic cylinder is used as a drive for moving the trolley.

The closest in technical essence is a device for thermal cutting of pipes, containing a base that moves along a trolley fixed to the base of the rails with a pair of drive wheels and a rack rigidly fixed to it, on which a cutter is mounted with the possibility of changing position (ed. USSR certificate No. 1632688 , class B 23 K 7/00, decl. 03/23/89, publ. 03/03/91).

Drive wheels through a gearbox are connected to an electric motor. The electric drive used to move the trolley allows you to adjust the speed of its movement in a wide range and with a deviation from its required nominal value within 1%, which satisfies the requirements for the accuracy of the speed of movement, for example a plasma torch, where this value is 2%.

A disadvantage of the known design of a device for thermal cutting of pipes is that it does not provide sufficient stability for the longitudinal cutting process necessary for preliminary cutting of longitudinal grooves at the pipe end, which ensures the separation of the cut ring into 3-8 parts.

This is because the movement of drive and non-drive running wheels along the guide rails is carried out due to the friction forces between the surfaces of the rails and wheels, and in many respects the magnitude of these forces depends on the physical condition of these surfaces, the presence of scale, moisture, roughness, uneven wear and can lead to the phenomenon of slippage and areas of braking and acceleration of the trolley while maintaining a constant speed of rotation of the running wheels themselves from the electric drive. This phenomenon violates the stability of the thermal cutting process. Uncuts may occur, which violates the separation of the pieces of the mixture from each other and leads to malfunctions of the equipment, since it is difficult to remove the mixture from the working area of the plasma torch.

Another disadvantage of this device is a significant skew on the cut end of the pipe, caused by the skew of the cart relative to the axis of the pipe.

The objective of the present invention is to provide a device that improves the quality of cutting by improving the stability of the longitudinal cutting process and the accuracy of the installation of the cart carrying the cutter relative to the axis of the pipe.

This object is achieved by the fact that in the device for thermal cutting of pipes containing a base, a trolley mounted on rails mounted on the base of the rails with a pair of drive wheels mounted on the shafts and a stand rigidly mounted on it, on which the cutter is mounted with the possibility of changing position, and the movement drive trolleys according to the invention, the trolley is provided with gear wheels mounted on the provided shaft consoles from the outside thereof with gears interacting with the gears E rails fixed on the basis of parallel rails, wherein the pitch circle diameter of the toothed gears is equal to the outer diameter of the bull wheel.

Such a structural embodiment of the device for thermal cutting of pipes will provide improved cutting quality by increasing the accuracy of the torch installation along the cutting line due to the fact that the presence of gearing on the shafts of the drive wheels eliminates the possibility of slipping of the wheels of the trolley along the guide rails, as a result of which the speed of the trolley is stabilized with a plasma torch in the process of cutting metal and, therefore, a smooth movement of the torch along the cutting line is ensured. In addition, a pair of gear racks mounted on the base on the outer sides of the running wheels and rigidly coupled with gears mounted on the shafts of the running wheels eliminates the skew of the cart within the guaranteed mounting clearances between the flanges of the running wheels and the guide rails (providing ease of rolling wheels on rails).

Absolute coincidence of the axis of the cart and, consequently, the axis of rotation of the plasmatron with the axis of the tube being processed, the absence of skew of these axes, significantly reduces the kosin of the cut end of the pipe.

The equality of the diameter d _{q of the} pitch circle of the gears and the outer diameter d _{to the} drive wheels gives the equality of peripheral speeds, since

where n is the number of revolutions per min.

To explain the invention, a specific embodiment of the invention is given below with reference to the drawings, in which:

figure 1 shows a device for thermal cutting of pipes, General view;

figure 2 is a view along arrow a in figure 1;

figure 3 - node B in figure 2;

figure 4 - node In figure 1 with the placement of the cutter outside the pipe.

The device for thermal cutting of pipes consists of a base 1 with rails 2, movable from the electric drive 3 along the rails 2 of the trolley 4 with a rigidly fixed stand 5, carrying a radially movable carriage 6 with a plasma cutter 7 and a drive 8 of rotation of the cutter 7.

The cart 4 has two pairs of running wheels 9 mounted on shafts 10 with bearings 11. One pair of running wheels 9 is connected to the electric drive 3, and the second pair is idle. Each shaft 10 of the drive wheels 9 is equipped with a console 12 on the outer side of the wheels 9, on which the gear 13 is rigidly mounted, engaged with the gear rack 14, rigidly mounted on the base 1, while the diameter d _{q of the} pitch circle of the gears 13 is equal to the outer diameter d _{to the} drive wheels (d _q = d _k ).

Before processing, the axis of the processed pipe 15 is combined in any known manner with the axis of rotation of the plasma cutter 7, with the trolley 4 retracted to its original position (shown by the dotted line in figure 1), the cutter 7 is in front of the pipe 15. When the electric drive 3 of the running wheels 9 is turned on, the trolley 4 with a cutter 7 starts a longitudinal movement. The stroke S of the trolley 4 is determined by the width of the cut ring, depending on the assortment of the processed pipes. The cutter 7 from the inside (figure 1) or outside (figure 4), moving together with the trolley 4, cuts a longitudinal groove 16, and then returns to its original position. The number of grooves, depending on the assortment of pipes, can usually be from two to ten and is determined by the required size of the charge. The cutter 7 is rotated by a predetermined angle, and the process of cutting the next groove is repeated. So, making a reciprocating movement of the cart 4 with the cutter 7, cut all the grooves.

At the end of the processing of the last groove, the rotary drive 8 of the cutter 7 is turned on, which during the rotation process cuts the pipe end. As the cutter 7 moves around the circumference, the cut pieces (parts of the ring) fall down and are removed from the treatment zone in any known manner.

After the end of the pipe has been processed, the carriage 4 is retracted to its original position by an electric drive 3. When the carriage 4 is moved, the running wheels 9 roll along the rails 2, while the stabilization of the speed of movement is provided by gearing of the gears 13 with the racks 14. The oscillation of the speed of the carriage 4 does not exceed 1% which is ensured by the control of the electric drive 3, and does not exceed the requirements for the fluctuation of the speed of the plasma torch 7, which should not be higher than 2%.

The proposed device for thermal cutting of pipes in comparison with the known ones can improve the quality of cutting by eliminating metal cuts, significantly reduce the braid of the processed pipe end, which will reduce metal waste during further machining of the pipe ends and reduce the time for this operation.

Claims (1)

A device for thermal cutting of pipes, comprising a base, a trolley mounted on rails mounted on a base, with a pair of drive wheels mounted on the shafts and a stand rigidly mounted on it, on which a cutter is mounted with a possibility of changing position, and a trolley movement drive, characterized in that the trolley equipped with pairs of drive wheels mounted on the provided shaft consoles from their outer side toothed gears interacting with gear racks mounted on the base of Allelic rails, wherein the pitch circle diameter of the toothed gears is equal to the outer diameter of the bull wheel.

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