RU2303189C1 - Device for joining plastic pipes with metallic valves - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: device comprises metallic flange provided with concentric ring projections, mechanism for fastening the pipe, and seal for sealing the butt. One of the projections embraces the pipe from outside, and the other one is in a contact with the inner surface. The seal is made of a spacer mounted on the face of the pipe. The fastening mechanism is provided with a cylindrical part made of a bushing having slots that define the flexible tabs interposed between the outer side of the pipe to be fastened and ring projection of the flange that embraces the pipe from outside. The flange is secured to the bushing by means of a row of screws whose cylindrical sections are set into the smooth openings made in the bushing. The second row of screws is arranged parallel to the first row of screws and cooperates with the flexible tubs of the bushing. The inner spaces of the device interposed between the inner side of the ring projection and outer side of the pipe are filled with epoxy compound through the openings in the ring projection that embraces the pipe from outside.

EFFECT: enhanced reliability.

2 dwg

Description

The invention relates to the field of engineering, in particular to devices providing the ability to install on plastic piping shut-off and control valves and steel bends.

A device for connecting pipes, developed by the American company "Great Plains Instruments INC" (US Patent No. 5004013, published 02.04.91). The device comprises a hollow element covered by a pipe with a threaded end and a slot between the ends. There is a locking rotary insert with holes in the wall and a locking ring. The disadvantages of the device include structural complexity, the abundance of mating elements, which significantly increases the cost of the connection, not guaranteeing increased reliability.

The Japanese company "Osaka Gasu KK" proposed a device (Japanese application No. 3085727, MKI F16L 23/02), which uses a monolithic body with sockets at the ends equipped with internal threads and recesses for sealing ring elements. As part of the fixing mechanism, threaded bushings with conical surfaces acting on hardened balls pressed into the pipe body are used.

The device developed by Osaka Gasu K.K. is not inferior in complexity to the American model. The use of balls leads to an unacceptable stress concentration in some places.

The use of complex structural elements in both the first and second cases involves the transfer of large volumes of metal into chips during machining, which unjustifiably increases the cost of the finished product.

As a prototype of the proposed technical solution, it is advisable to dwell on the invention created by specialists of the Ufa Petroleum Institute (AS USSR No. 1733819 dated 05/15/92) - "Device for connecting plastic pipes with metal pipes and fittings".

In the aforementioned device, to increase reliability, a detachable flange (composed of three parts) is used, which is fixed to a plastic pipe using standard fasteners. The flange is equipped with an annular protrusion acting on the surface of the plastic pipe. A sleeve with an annular cavity is installed inside the pipe, in which the seals are located - elastic rings that ensure the tightness of the joint. Before installation, the pipe section is heated to t ° - 60-70 ° C and in such a plastic state is pressed by the annular protrusion of the flange into the annular cavity of the sleeve installed inside the pipe. To prevent the plastic fibers from being cut off, a hyperbolic cross-section is given to the hollow in the sleeve and the curvature of the flange protrusion.

The solution proposed by the specialists of the Ufa Petroleum Institute (AS USSR No. 1733819) ensures reliable fastening of a smooth plastic pipe. It involves the use of standard fasteners and sealing the joint with rubber rings that seal the junction of metal with plastic.

However, a number of significant drawbacks should be noted.

Firstly, deep heating of the pipe does not pass without a trace for plastic and can affect long-term operation.

Secondly, the pipe cross-section at the location of the connection is significantly reduced, which is undesirable.

And, finally, the use of a flange consisting of three mating independent elements creates technological difficulties and increases the volume of metal transferred to the chips.

The objective of the invention is to develop a device for connecting plastic pipes with metal and fittings, eliminating the need to heat the plastic pipe before assembly, with the most rational scheme of application of forces developed by fasteners, and to minimize the reduction of the pipe cross section at the location of the device.

To solve the problem, in a device for connecting plastic pipes with metal pipes and fittings, containing a metal flange with an annular protrusion that encloses the pipe from the outside, and a pipe fastening mechanism and a sealant to seal the joint, the flange additionally contains a concentrically located annular protrusion that contacts the inner pipe surface. The sealant for sealing the joint is made in the form of a gasket located on the end of the pipe, and the mounting mechanism contains a cylindrical part in the form of a sleeve with slots forming deformable petals located between the outer surface of the fixed pipe and the annular protrusion of the flange covering the pipe from the outside, which is rigidly fixed to the sleeve with slots through a series of screws, the cylindrical parts of which are inserted into the smooth holes of the sleeve. Parallel to the first row of screws, a second row of screws is placed, acting on the deformable lobes of the sleeve, the internal cavities of the device located between the inner surface of the annular protrusion covering the pipe outside and the outer surface of the pipe filled with epoxy compound through the holes in the annular protrusion covering the pipe outside.

The invention is illustrated by drawings.

Figure 1 shows a General view of the device for connecting plastic pipes with metal and fittings, figure 2 is a cross section of the proposed device.

The device for connecting plastic pipes with metal and fittings includes a flange 1, which is equipped with concentric annular projections welded to it, one of which is external - 2 is located above the outer surface of the plastic pipe 4, and the second inner - 3 is in contact with its inner surface . In this case, the plastic pipe 4 has an internal groove for pairing on a movable fit with the inner metal annular protrusion 3. The external annular protrusion contains two parallel rows of screws 8 and 9 arranged uniformly radially around the circumference. The joint 5 is sealed by a gasket 5 located on the end of the plastic pipe 4, it is compressed by external forces during assembly of the device until the fastening mechanism is actuated. The fastening mechanism includes a cylindrical part 6, made in the form of a sleeve with slots forming deformable lobes 7, placed above the surface of the pipe 4. Along with the slots, part 6 has a number of smooth holes into which the cylindrical parts of the screws 8 are inserted, providing a rigid connection of the cylindrical part 6 with an external annular protrusion 2. On the petals 7 act the screws 9 located uniformly around the circumference of the external annular protrusion 2, when tightened, the teeth of the petals 7 are pressed into the surface t 4. At the same time a decreasing chosen clearances between the cylindrical part of the screw 8 and the internal surfaces of the holes formed in the part 6. The combined effect of tightened screws 8 and 9 of the efforts made externally to the gasket 5, remain for the life cycle, providing reliable joint sealing.

After assembling the device, the inner surfaces of the annular protrusion 2 are filled with epoxy compound through the holes 10 and 11 made in the outer annular protrusion 2. Gaskets 12 and 13 are installed in the grooves of the outer annular protrusion 2 and the cylindrical part 6, which exclude the possibility of the compound flowing out during the pouring process.

A device for connecting plastic pipes with metal pipes and fittings is assembled in the following sequence.

The plastic pipe is pierced along the inner diameter to fit the annular protrusion 3, which does not weaken the cross section, since the decrease in the wall thickness of the plastic pipe after assembly is compensated by the internal metal annular protrusion 3. Install the gasket 5 and press the pipe end 4 against it, providing the necessary compression ratio .

Sequentially tighten all the screws 8, the cylindrical protrusions of which enter the holes of the cylindrical part 6, which leads to the formation of a hard stop due to the mechanical connection of the elements of the system 2-6.

Tighten the screws 9, pushing the petals 7 into the surface of the pipe 4. After the necessary exposure, taking into account the relaxation properties of the plastic, an additional tightening of the screws 9 is performed.

Taking into account the relaxation properties inherent in plastic, which provide a change in the geometric shape under the action of externally applied forces, a slight change in the nature of the fit between the inner surface of the pipe 4 and the surface of the inner metal annular protrusion 3 is possible during assembly when the screws 9 are tightened when the conditions for their tightening are met after some time that does not violate the joint seal.

Remove the external load and check the finished product for leaks. If the test results are positive, the epoxy compound is poured through holes 10 and 11 and the product can be put into operation.

After fully tightening the screws 8 and 9 and filling the epoxy compound, their protruding screw heads 8 and 9 can be cut off, providing the conditions for applying a protective film.

The tensile screws used in the structure do not work and, after performing their power function, are monolithic forever.

The hardened mass of the epoxy compound turns the petals of the sleeve 6 into a monolith, which has a strong connection with the inner surface of the protrusion 2 and snugly fits to individual sections of the pipe 4. Since the petals of the part 6 are pressed into the surface of the pipe 4 to a sufficient depth, the pipe 4 is reliably fixed monolithic part 6, whose petals are devoid of initial compliance.

Depressurization under the influence of a temperature difference is completely excluded, the pipe section 4 is integral with the protrusion 2 and additionally relies on the annular protrusion 3.

The structure uses ring-shaped parts that are simple in shape, which ensures minimization of the amount of metal transferred to the chips.

Reducing the bore at the location of the flange is minimal.

A rational pattern of application of forces developed by standard fasteners is provided.

Claims (1)

A device for connecting plastic pipes to metal pipes and fittings, comprising a metal flange and an annular protrusion that encloses the pipe from the outside, and a pipe securing mechanism and a sealant for sealing the joint, which is characterized in that the flange further comprises a concentrically arranged annular protrusion that contacts the inner surface pipes, a sealant for sealing the joint is made in the form of a gasket located at the end of the pipe, and the mounting mechanism contains a cylindrical part in Idea of the sleeve with slots forming deformable lobes placed between the outer surface of the fixed pipe and the annular protrusion of the flange, covering the pipe from the outside, which is rigidly fastened to the sleeve with slots by means of a series of screws, the cylindrical parts of which are inserted into smooth holes of the sleeve, parallel to the first row of screws, the second a series of screws acting on the deformable petals of the sleeve, the internal cavities of the device located between the inner surface of the annular protrusion, covering pipe outside, and the outer surface of the pipe is filled with epoxy compound through the holes in the annular protrusion, covering the pipe from the outside.

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