JPH0228759B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications This invention relates to a pipe joint.

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION Plastic materials in general, and fluoropolymer plastics in particular (such as polytetrafluoroethylene (PTFE) and ethylenetetrafluoroethylene (ETFE)), are commonly used as devices and components in analytical instruments and the like. It can be adapted to almost any application in laboratory and instrumentation for interconnecting. An important advantage of materials such as PTFE is that they are exceptionally chemically inert and allow the tube to be cut to length and bent easily.

Unfortunately, such plastic materials, and PTFE in particular, have a degree of porosity to gases and vapors. This porosity prevents them from being put to certain applications despite their other excellent chemical properties. The flow of these gases impairs the analysis performed by altering the properties of the analyzed material or otherwise adversely affecting the test. Otherwise, such flow may pose a risk of hazardous materials escaping by diffusing through the pipe walls and contaminating the environment.

In addition to these limitations, the use of these materials as plastic tubing to convey fluids under pressure has been limited to relatively low-pressure applications until now because the tubing and fittings available to date are They were unable to withstand relatively high internal pressures, ie, more than 1000 pounds ^per square inch. Above this pressure barrier the tube wall is found to weaken, an abnormal increase occurs in the tube and if the pressure is immediately reduced, the tube will burst.

SUMMARY OF THE INVENTION The present invention provides an improved pipe fitting for use with an improved pipe.

Both the improved tube and the improved fitting seek to separate the flexible inner plastic tube from its surroundings and also prevent the plastic tube section from bursting at high internal pressures.

According to the improved tube used in this invention,
A tube for containing fluid at a pressure of 1000 pounds (approximately 454 kg) or more per square inch (approximately 0.036 m ² ), comprising an inner plastic tube and an outer reinforcing sheath, in which the inner tube can slide within the outer sheath. It's a good thing.
This outer reinforcing sheath is formed from metal or impermeable plastic or rubber materials or composites thereof.

A pipe fitting according to the invention is an improved fitting for use with pipes. The tube includes an inner tube of plastic material and an outer reinforcing jacket into which the inner tube is slidably fitted. The fitting includes a thrust section, a block section, a rigid housing section, a sleeve, and spring means.

The thrust section has an opening to which one end of the outer reinforcing sheath is secured. The block consists of an elastically deformable plastic material. The block also has two parallel end faces facing each other and an axial hole extending between the two end faces.
One of the end faces abuts the inner end face of the thrust portion. A block is arranged to allow the internal tube to pass through the axial hole. A rigid housing is disposed about the block and restrains the block from radially outward deformation when the block is subjected to a compressive force between the two end faces. The sleeve encloses the coated tube, thrust section, block and rigid housing. Spring means act on the outer end face of the thrust portion to bias the other end face of the block spaced apart from one end face into sealing engagement with the planar surface of the cooperating member.

The cooperating member is conveniently open in alignment with the axial hole in the plastic block mentioned above and includes a flat seat which extends into the sleeve from the opposite end of the sleeve or vice versa. in the opposite flat end faces of other similar plastic blocks similarly located, and in the second part of the inner plastic tube.
and that the first mentioned inner plastic tube is connected to the second mentioned inner plastic tube without any destruction of the surrounding protection so as to prevent rupture of the tube due to high internal pressures. is made possible.

In one embodiment, an internal plastic tube extends through an axial hole through the block and is sealingly retained therein.

In another embodiment, the tube is cut flush with the end surface of the thrust section that abuts the block, and the diameter of the hole through the block is chosen to correspond to the inside diameter of the inner plastic tube.

In a third embodiment, the tube is flanged and sandwiched between the inner end face of the thrust section and the outer end face of the block of plastic material.

In any of the three embodiments described above, a barb-like projection, typically annular in shape, is formed on the inner surface of the through hole in the thrust section, the direction of the barb being
The direction of the jaws is such that when the inner tube is pulled in a direction that pulls the tube away from the thrust section and away from the block of plastic material, the jaws engage the wall of the inner tube.

In the third embodiment described above, an axial annular projection is formed through the thrust part and pivotally about the outlet of the hole, so that the tube sandwiched between the thrust part and the block The flange is pinched by an annular ridge formed by an axial annular projection and thereby provides radially inward and axial Prevents flow in an outward direction.

The plastic tube is secured within the block of plastic material by means of an adhesive instead of or in addition to the use of the previously mentioned jaw-like or annular projections.

Although the thrust part and the rigid storage part do not necessarily have to be integrated, preferably, the thrust part is formed by the base of the cup-shaped member, and the rigid storage part is formed by the cylindrical shape of the cup-shaped member extending from the base. It is composed of departments.

Conveniently, there is provided a threaded member adapted to be movably retained at the end of the sleeve, through which the cladding tube and other components are introduced into the sleeve, the threaded member including a through hole. , through which the cladding tube can pass, and the threaded member constitutes a surface on which the spring means serves to create the required axial thrust on the outermost end face of the thrust section.

Conveniently, the threaded member is in the form of an externally threaded cylindrical plug, the plug having an outermost surface for allowing a tool to be fitted therein for threading the threaded member into the sleeve. At least one recess is formed.

By making the threaded member from metal, the spring means is located between two simple metal surfaces, one metal surface being the inner end face of the threaded member and the other metal surface being the outer end of the thrust member. This is the end face towards which it faces.

Conveniently, the spring means include at least one set;
It preferably includes three sets of spring steel washers (sometimes known as bevel washers and sold under the trade name "Belville" washers).

Preferably, the rigid housing in which the block of plastic material is housed is itself precisely aligned within the sleeve and has an inner plastic tube with a through hole in the opposite flat end face or flat seat. When the fitting is assembled, the block of plastic material abuts the open flat end surface or flat seat.

According to a preferred feature of the invention, in which the thrust part and the rigid storage part constitute the base and the cylindrical part of the cup-like member, the open circular end of the cylindrical part of the cup into which the block is fitted is chamfered. and the block of plastic material is cylindrical and has a diameter such that it fits within the cup and projects axially beyond it, the axially projecting portion being the cylindrical portion of the cup-like member. The block has a circular chamfered edge which increases in diameter relative to the rest of the block to form a flange of firmly embedded deformable plastic material.

The opposite flat end surface against which the inner end surface of the first-mentioned block abuts is the similar inner end surface of a similar plastic block provided in a similar manner in the sleeve, and the second-mentioned block is also including an annular flange of deformable plastic block material embedded in the chamfered annular lip of the cup-shaped member, the rear of the two cup-shaped members are supported by two opposed spring assemblies. The applied axial thrust causes the two annular flanges of deformable plastic material to be pinched between the two chamfered annular edges of the two cup-shaped members, so that each cup A block of plastic material will be housed within the shaped member and a good peripheral seal will thereby be formed with the tab so created.

In another embodiment of the invention, the inner end face of the plastic block is formed with a tapered recess, the angle of the taper being such that the opening of the recess in the inner end face has a larger diameter than the hole passing through the block. The plastic tube is pushed through the block and the flat seat preventing the block of plastic material from being otherwise pushed is provided with a complementary conical surface extending into the protruding plastic tube. The plastic tube then bulges radially outward until it is clamped between two complementary conical surfaces thereby forming a good seal at the connection point.

Preferably, the plastic material is polytetrafluoroethylene (PTFE).

Preferably, the outer reinforcing coating consists of metal,
Hardened plastic materials may alternatively be used.

The sleeve is formed from metal or hardened plastic material.

As a joint, the sleeve connects two
Fits onto the end of each tube.

If the tube is to be connected to a component, this component is such that it forms a flat seat (or conical prominent surface) against which the plastic block is resiliently biased in a sealing manner; And the sleeve may be a separate attachment which is conveniently formed integrally with the component or which is secured thereto, for example by a threaded engagement.

Embodiments of the invention The invention will be explained by way of example with reference to the accompanying drawings, in which: FIG.

A mounting is shown in the drawing in which two pipes can be connected to each other. Each pipe is formed from two parts: an inner plastic 10 and an outer metal cladding 12. This installation requires the symbol -
Sections of these mounting components and pipe sections on the right half of the drawings that are symmetrical about the center line indicated by are used to represent similar sections on the left side, although with suffixes added. are designated by similar reference numerals.

The outer jacket extends through a hole 14 which is provided through a circular outwardly threaded plug 16 having tool recesses 18 and 20 in its outer surface and having two or The tool is allowed to be inserted and the bung is turned into engagement or out of engagement.

The main part of the installation is the generally cylindrical sleeve 22.
The sleeve 22 has a central region of reduced diameter and is formed with threads at two ends of its inner surface.

With particular reference to the left end of the installed state shown in FIG. Extending therethrough, washer 24 constitutes a resilient compression spring.

The washer 24 is sandwiched between the inner end surface of the stopper 16 and the outer end surface of the metal cup 26 .
has an annular recess 30 surrounding the through hole 28 and the outlet of the hole 28 in the end face of the cup, the recess 30
Accept the inner end of 2. The shoulder formed by the recess 30 constitutes an abutment against which the end of the sheathing rests.

The cup 26 is generally cylindrical, and has a base 261
and a cylindrical portion 262. A PTFE tubular block designated by the reference numeral 32 is fitted into the tubular portion 262 . A through hole is formed in the block such that through hole 34 is aligned with through hole 28 in base 261 of cup 26 and plastic inner tube 10 extends completely through aligned holes 28 and 34. The end of the inner tube 10 is cut in alignment with the innermost flat end 36 of the block 32.

Within the hole 28 there is an annular jaw-like projection 38 which allows the plastic tube 10 to be pushed through the base 261 of the cup 26 from left to right, but the tube immediately in the opposite direction (i.e. (from right to left) and directed into the hole in such a manner that the jaws 38 engage the walls of the tube and prevent the tube from being pulled in a rearward direction.

Although the jaws 38 have been described as a single annular projection, the present invention is not limited to a single annular projection, and the invention is not limited to a single annular projection, nor can two or more such annular projections be used. A plurality of jaw-shaped teeth are formed in the bore 28 and need not be arranged in an annular manner, and can also be formed in the tube in a manner similar to that described for the annular barb 38. It will be appreciated that it may also be positioned to interlock with a wall.

The projecting ends of blocks 36 and 36' are formed with annular flanges of a larger diameter than the remainder of the blocks and are designated by reference numerals 39 and 39', respectively. annular flange 39
and 39' are the two cup-shaped members 26 and 2.
It is fastened between the 6' chamfered circular edges,
and the axial thrust exerted on the rear of the two cup-like members 26 and 26' by the springs 24 and 24' creates an excellent seal around the two flanges 39 and 39' formed between them. It works to form a ring-shaped knob.

The fit is assembled by first threading the plug 16 into the outer jacket 12 with the inner tube 10 extending therethrough. A "Belville" washer 24 is then screwed onto the sheathing 12. The sheathing is of a length such that the inner plastic tube 10 projects a few inches beyond the end of the sheathing, and the protruding plastic end is formed into a cup 26 containing the PTFE block 32, for example by shaving. It is tapered so that it can be introduced into the hole 28. The plastic tube is pulled through the aligned holes in the cup and block until the end of the sheath 12 is received within the recess 30 and remains anchored therein. The end of the plastic tube 10 protruding from the end surface 36 is then adjusted so that the end of the tube is flush with the end surface 36 of the block 32. tube 12'
is likewise secured within a block housed within the cup-shaped member 26'.

Although not shown, adhesive or solder or similar means may be used to secure the covering 12 within the annular recess 30 on the end face of the cup 26.

In a similar manner, the end of the shaved or tapered tube 10 is covered with adhesive before being introduced into the hole through the block 32, so that the tube and block are free of adhesive. When cured, they are firmly bonded to each other.

The cup 26 is now introduced into one end of the cylindrical sleeve 22 and the stopper 16 is turned so as to engage the thread on the inner surface of the sleeve and be screwed in the mating direction, thereby making the "Belville" ” compresses washer 24 and exerts an axial thrust on the rear of cup 26.

A similar assembly is inserted into the opposite end of the mated state, and bung 16' is similarly rotated and the two
The pressure exerted between the two abutting surfaces 36 and 36' is sufficient to seal the connection between the two tubes 10 and 10' and to withstand the pressure of the fluid within the tubes.

The present invention allows two plastic tubes to be connected to each other at least in part using a metal fitting, which provides substantial strength to the fit and provides substantial axial thrust through the joint. operated across the intersecting and sealing interface;
It will therefore be appreciated that there is little possibility of leakage occurring in the mated condition.

The invention also allows the thrust acting across the sealing interface (between the two blocks 32 and 32') to be varied so that the mating condition can be adjusted just as the pressure is being applied. Only the necessary thrust is exerted on the plastic blocks 32 and 32'.

FIG. 2 is an end view of the plugs 16 and 2 in their assembled, mated condition, with the metallization 12 and inner tube 10 projecting through the center of the plug.
tool recesses 18 and 20 are shown. It is shown threaded onto the end of the plugged fitting 22, the fitting being shown in this case to have a circular cross-section. The sleeve 22 need not have a circular external shape and a square or hexagonal surface is advantageously formed around the external surface at least over its length, which exerts a torque on the plugs 16 and 16'. It will be understood that it may be made available to help.

FIG. 3 is a sectional view taken along the line in FIG. 1;
The innermost end of the tube 10 is shown cut flush with the end surface 36 of the block 32 anchored within the cup 26.

According to a preferred feature of the invention, a close sliding fit is provided between the outer surface of the cup 26 and the inner surface of the reduced diameter portion of the sleeve 22, so that the cup 26
6' is aligned with the rest of the joint. In this way, excellent alignment of the fluid passages formed by tubes 10 and 10' can be achieved.

The end face 36' of the opposite block 32' introduced from the right-hand end of the fixture 22 is secured with a through hole communicating therethrough with an internal fluid tact within a component such as a valve, pump, etc. It will be appreciated that the seat can be replaced by a flat seat. The mated right-hand end as shown in FIG. It may be a threaded attachment surrounding the central opening to be connected.

The major advantages of this invention would be lost if the flat seat surface of the alternative arrangement just mentioned (but not shown) was not formed from a plastics material such as polytetrafluoroethylene, and As a result, the outer sleeve 22
It may be formed from the PTFE itself, or it may be formed from metal and bonded to the PTFE housing of the component (not shown) as previously discussed. Alternatively, the PTFE insert may be inserted into the plastic block 3 of the embodiment shown in FIG.
replacing the surface 36' formed by 2';
It may be placed in a metal fitting to form a PTFE passage and a flat end seat.

The present invention is particularly useful for plastic tubing and fittings to be achieved in systems where significantly higher pressures are required to be contained within the tubing and fittings than heretofore standard plastic components. enable the benefits of This mainly consists of plastic tubes 10 and 1.
0' arises from the fact that it is entirely contained within a metal cladding or within a passageway within a member of plastic material which is itself bounded by metal at all points along the length of the plastic tube. It is something.

Since most plastic materials are porous to certain gases and vapors, the presence of a metal coating prevents the ingress of oxygen, nitrogen, carbon dioxide, etc. from the surrounding air and therefore prevents liquids from entering otherwise. This allows for the ingress of such gases to be transported and accumulated in the pipes without risk of contamination. This is particularly important if all systems in which this tube is used have to measure the content of gases in liquids, for example the content of oxygen in fluids.

The invention is not limited to any particular method of securing plastic tube 10 to cup 26 and block 32, and any convenient method may be used as described in the foregoing description without reference to the drawings. It should be understood that

Effects of the Invention As described above, according to the present invention, the end surfaces of two plastic tubes communicating with the holes in the plastic block are brought into contact via the thrust portion to which the external reinforcing coating is fixed. This allows the two plastic tubes to be spliced together. At this time, the force applied to the thrust section imparts considerable strength to the joint between the plastic tubes. Therefore, a considerable axial thrust
It acts across the joint of the plastic tube and across the sealing interface existing between the other end face of the block and the end face of the cooperating member. Therefore, 2
With the two plastic inner tubes joined together, there is little chance of fluid leaking out of the tube.

Also according to the invention, the thrust acting across the sealing interface can be varied by spring means acting on the outer end face of the thrust portion. Therefore, while the two internal tubes remain joined together using the pipe fitting, only the necessary thrust, including the externally applied pressure, can be exerted on the block and cooperating member to be brought into sealing engagement. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view through a pipe fitting embodying the invention, in which the mated component parts are shown in cross-section in the left half of the drawing and not in cross-section in the right half of the drawing. FIG. 2 is an end view of the fitted state shown in FIG. 1. FIG. 3 is a sectional view taken along the line--in FIG. 1 in a fitted state. In the figure, 10 and 10' are the inner plastic tubes, 12 and 12' are the outer metal coatings, 22 is the sleeve, 24 is the bevel washer, 261 is the base of the metal cup, 262 is the cylindrical part of the metal cup, and 32 is the cylindrical part. Block, 34 is axial hole, 36, 36'
indicates the innermost flat end of the block, and 38 indicates the jaw-like protrusion.

Claims (1)

Claims: 1. A fitting for a tube comprising an inner tube of plastic material and an outer reinforcing sheath into which said inner tube is slidably fitted, said sheath 12 being secured at one end. a thrust part 261 having an opening, made of an elastically deformable plastic material, having two parallel end faces facing each other, and an axial hole 34 extending between the two end faces; A block 32 is arranged around the block 32, one of which abuts the inner end surface of the thrust part and is arranged so that the inner tube 10 is inserted into the hole, and the block is arranged between the two end surfaces. a rigid housing 262 for restraining said block from radially outward deformation when subjected to compressive forces; and a sleeve encasing said coated tube, said thrust section, said block and said rigid housing therein. 22; acting on the outer end surface of the thrust section to resiliently urge the other end surface of the block spaced apart from one end surface into sealing engagement with the flat surface 36' of the cooperating member; and spring means (24). 2. The pipe fitting of claim 1, wherein the cooperating member has an opening aligned with an axial hole in the block. 3. A pipe fitting according to claim 2, wherein the cooperating member is a flat seat within the sleeve 22. 4. Said cooperating member is a second plastic block similar to said block 32 and sealingly engaged with a second inner plastic tube 10' housed within a second outer sheath 12'. A pipe joint according to claim 2. 5 An annularly arranged jaw-shaped protrusion 38 is formed on the inner surface of the opening of the thrust part 261, and the extension direction of the jaw is such that the inner tube is separated from the block and the outer part of the thrust part 261 is extended. A pipe fitting according to claim 1, having a direction adapted to engage the wall of the inner pipe when pulled in the direction of pulling the pipe. 6. According to claim 1, the thrust portion is constituted by a base of a cup-shaped member, and the rigid storage portion is constituted by a cylindrical portion of the cup-shaped member extending from the base. pipe fittings.