RU2015442C1 - Device for threaded joining pipelines with cutting in ring - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: union and a coupling nut compress a ring cutting in the pipe. An annular inner groove is made in the front part of the ring on the side of the joint. Diametrically located cuttings which depth is no more than half the ring width are made in the back side of the ring. EFFECT: improved structure. 4 cl, 1 tbl

Description

 The invention relates to the field of mechanical engineering and can be used when performing a collapsible threaded connection of metal pipelines with a cutting ring for axial mounting.

 Known pipe connections using cutting rings.

 One of the known devices is a pipe coupling, consisting of two interacting parts, axially moving one relative to the other. Between these parts is a pressure sleeve with two inner shoulders of the same diameter.

 The front shoulder is made in the form of a cutting edge rotating in a pipe. A tight connection between the pressure sleeve and the pipe is due to the formation of an annular protrusion of the pipe material running in front of the cutting edge. However, due to the large radial stiffness of the ring, a reliable tight connection can be made only with a minimum radial clearance between the outer diameter of the pipe and the inner diameter of the cutting ring.

 A screw pipe connection is also known, the connecting elements of which are axially screwed into one another. An annular recess is provided between these elements for the end of the pipe, onto which the O-ring is fitted. The ends of the connecting elements located on both sides of the sealing ring expand one relative to the other in the form of a hollow cone. A mating end with a radial thickening is provided on one side of the o-ring. To this end surface, when screwing, a movable inner end is pressed, pushing the sealing ring. On the other hand, the o-ring has a cylindrical cutting end, which is radially compressed when the other, stationary, inner end faces. The cutting end has two sealing edges that cut into the pipe surface. However, due to the fact that the contact of the end surface of the end of the ring with the surface of the nut occurs on the circumferential edge, high hardness of the clamping nut is necessary to enable subsequent disassembly of the threaded connection.

 In our country, GOST 23354-87 "Threaded piping connections. Cutting rings" applies.

 A cutting ring made in accordance with this standard is used when making threaded pipe connections. At one end of the connected pipeline there is a fitting. At the end of another pipeline intended for connection, a cutting ring and a union nut are put on (GOST 23353-87).

Known ring has a leading edge that cuts into the body of the pipe when making the connection, and a thickened back in the form of an annular protrusion. The protrusion has a receiving cone with an angle of 90 ^about from the end part to improve contact with the collar of the union nut. However, such a design of a cutting ring imposes certain restrictions on the conditions for its use: a reliable connection is possible only for cold-drawn pipes of increased accuracy, i.e. calibrated pipes, provided that the gap between the outer diameter of the pipe and the inner diameter of the ring does not exceed 0.10-0.15 mm; to make the connection, preliminary compression of the cutting ring on the pipe pipe is required in a special technological device made in the form of special fittings hardened to hardness HRC42-45 and with control of the increased nut tightening torque. Thus, the absence of calibrated pipes does not allow a threaded connection with a cutting ring.

 The purpose of the invention is to increase the reliability of the connection of steel pipes of any accuracy class.

= 0.02...0.05 (I)

=0.4...0.1 (II) (IV) где h - глубина проточки;
l - длина проточки;
d - наружный диаметр кольца в его передней части;
d_вн - внутренний диаметр кольца в его передней части;
d_тр - наружный диаметр подсоединенной трубы.This is achieved due to the fact that in the device for the threaded connection of pipelines with a cutting ring containing a fitting at the end of one of the connected pipelines and a nut at the connecting end of the pipe of another pipe, the cutting ring is made with an annular internal groove in the front and diametrically arranged slots in the back parts of the ring whose depth does not exceed half the width of the ring. It is advisable to choose the depth and length of the groove depending on the outer diameter of the connected pipe from the ratio:

= 0.02 ... 0.05 (I)

= 0.4 ... 0.1 (II) (IV) where h is the depth of the groove;
l is the length of the groove;
d is the outer diameter of the ring in its front;
d _vn is the inner diameter of the ring in its front part;
d _tr - the outer diameter of the connected pipe.

 Thus, a substantially different embodiment of the cutting ring is proposed, providing the necessary radial compliance of the front of the ring while maintaining the axial stiffness of the ring as a whole.

 In the above ratios, the values of 0.05 (from the first ratio) and 0.4 (from the second ratio) are selected for pipes of smaller diameter, the values of 0.02 and 0.1 are selected for pipes of the largest diameter. This embodiment of the ring allows a reliable threaded connection of any pipes, including non-calibrated and pipes with a welded longitudinal seam, as well as pipes having non-circularity, and in the case of a large gap, up to 1 mm, between the inner diameter of the ring and the outer diameter of the pipe.

 A comparison of the inventive device for a threaded connection of pipelines with a cutting ring with the one selected as a prototype shows that the proposed solution has a combination of new distinctive features set forth in the characterizing part of the claims and, therefore, meets the criterion of "novelty."

 Comparison of the claimed device not only with the prototype, but also with other technical solutions in this technical field, did not allow us to identify new properties of signs and new features that distinguish the claimed device from the prototype device, despite the wide use of cutting rings.

 The proposed implementation of the annular groove, the choice of the optimum ratio of depth and width of the groove with respect to flexibility allows the use of a thread interference to realize a wedge seal, to ensure reliable connection of pipelines and to solve the problem of making threaded connections with a cutting ring, removing restrictions on accuracy on pipes. The proposed solution guarantees a reliable connection when using pipes in a wide range of diameters and with a pressure in the pipeline of 6.0 MPa and higher. Thus, the proposed technical solution meets the criterion of "significant differences".

 The following is a specific example of the implementation of the proposed device for a threaded connection of pipelines.

 In FIG. 1 shows a device for threaded connection of pipelines with a cutting ring, section; in FIG. 2 - a cutting ring; in FIG. 3 - node I in FIG. 2.

^{=0.02...0.05 (III)}

^=0.4...0.1
Стенка проточки, примыкающая к передней кромке кольца, выполнена со скосом 35^о.At the end of the pipe 1 intended for connection, there is a fitting 2. At the end of the connected pipe 3 of the other pipe there is a cutting ring 4 and a union nut 5. The fitting 2 and nut 5 are standard parts and are selected according to the thread parameters with the possibility of making a threaded connection. The fitting 2 has a receiving cone with an angle of 24 ^about . Crash ring - original part. The front part of the ring 4 is the working part and is made thinned with an inner annular groove and, therefore, has less rigidity compared to the back part of the ring - the supporting one. The width of the ring is selected taking into account the outer diameter of the connected pipeline pipe for pipes with an outer diameter of 6-16 mm, a ring of 9 mm wide is sufficient for pipes with a diameter of 18-42 mm, the width of the ring is selected in the range of 10-13 mm. The depth and length of the groove are also selected taking into account the outer diameter of the connected pipe, namely, from the following ratios:

^{= 0.02 ... 0.05 (III)}

^{= 0.4 ... 0.1}
The wall of the groove adjacent to the front edge of the ring is made with a bevel of 35 ^about .

The outer side of the leading edge has a technological radius of curvature. Thus, the thinned part of the ring ends with a leading edge 0.3-0.5 mm thick, the inner diameter of which is equal to the nominal outer diameter of the connected pipeline. The back of the ring 4, facing the inside of the nut 5, has four diametrically opposite slots. The depth of the slots is close in magnitude to the width of the outer lip of the ring. The width of the slots is 2.0-2.5 times less than the length. The presence of slots on the cutting ring for pipes with an outer diameter of more than 16 mm allows increasing the radial compliance of the rear part of the ring in order to provide additional contact between the cutting ring and the pipe and centering the ring on the pipe with large radial clearances. To ensure good contact of the ring 4 with the inner shoulder of the nut 5, the rear end surface of the ring has a receiving cone 43 ^about .

 The device operates as follows.

 On the free end of the pipe 3 of the pipeline to be connected, put on the outer nut 5 and the ring 4. The free end of the pipe 3 of the pipeline is inserted into the fitting 2 of the pipe 1 and is advanced until it abuts against the shoulder of the fitting 2. Then start screwing the nut 5 onto the fitting 2. The nut 5 presses on the trailing edge of the ring 4. The ring begins to move and, with its leading edge, enters the receiving cone of the fitting 2. With a further rotation of the nut 2, the ring 4 advances into the receiving ring of the fitting 2. This starts compression 4 ring diameter. The front edge of the ring 4 is pressed against the outer surface of the pipe 3. With further tightening of the nut 5, the axial displacement of the ring 4 continues towards the fitting 2, the thinned part of the ring 4 is deformed and the leading edge of the ring 4 is cut into the body of the pipe 3.

 The process will end when the edge of the receiving cone of the fitting 2 is aligned with the straight edge of the inner groove of the ring 4, i.e. the thinned part of the ring will be passed. Since the stiffness of the ring in the specified zone is higher, deformation of the ring in this zone does not occur. When the leading edge of the ring 4 is deepened into the body of the pipe 3, metal is extruded, and a ledge is formed on the pipe surface, which prevents the ring from being pulled out and breaking the connection. The ring can be rotated with the nut pressed out in this groove formed in the pipe body, but the ring can only be removed by cutting the pipe.

 Thus, in the final form, in the connection of pipelines with a cutting ring, a peculiar wedge is formed under the action of the interference thread, significantly increasing the reliability of the connection. There is a seal: the inner cone of the fitting 2 - the cutting ring 4. The dimensions of the cutting ring, when the dimensions of the connected pipe are known, are determined in accordance with ratios (III) and (IV) (see table).

Claims (1)

 DEVICE FOR THREADED CONNECTION OF PIPELINES WITH CUTTING RING, containing a fitting, a flare nut and a ring that is crimped or cut into the pipe, characterized in that an annular groove is made in the front of the cutting ring from the joint side, and the diameter is diametrically cut in the back of the ring which does not exceed half the width of the ring.

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