TECHNICAL FIELD

The present invention relates to a tube connector comprising an expandable gripping portion disposed interiorly in an end portion of a first tube and a substantially frusto-conical or cuneiform expander portion expanding the gripping portion on relative axial movement, and a drawing device such as a screw or bolt for realizing the axial movement.

BACKGROUND ART

Tube connectors of the type intimated by way of introduction are previously known in the Art. One such tube connector has a sleeve which is slit or otherwise expandable in the transverse direction and in which a conical expander body is retractable which realizes the transversely directed expansion. A tube connector of this type may undeniably provide a good grip in a surrounding tube, but it is impossible, with such a tube connector, accurately to secure the axial position of the tube in relation to the tube connector.

As regards connectors for jointing pipes or tubes aligned with one another, the above-described prior art tube connector cannot be employed, nor can it be modified, since it is not possible to ensure that the tube ends are drawn tight to one another.

PROBLEM STRUCTURE

The present invention has for its object to devise a tube connector of the type mentioned by way of introduction, the tube connector being designed in such a manner as to obviate the drawbacks inherent in prior art connector devices. More specifically, the present invention has for its object to devise a connector which permits a reliable retraction of the connected tube to a precisely predetermined position. Furthermore, the present invention has for its object to devise a tube connector which provides stable coupling without the possibilities of transversely directed shifts between mutually interconnected tubes. The present invention also has for its object to devise a tube connector which is simple and economical in manufacture,

convenient and rapid in assembly and which gives an extremely stable coupling in the axial direction.

SOLUTION

The objects forming the basis of the present invention will be attained if the tube connector mentioned by way of introduction is characterized in that the expander portion has its thicker end turned to face an abutment portion which, in the transverse direction of the tube, projects out so as to prevent axial movement of the tube; and that the gripping portion is, under expansion, drawable towards the abutment portion.

Moreover, in a first embodiment of the present invention, it applies that there is disposed, on either side of the abutment portion, an expander portion and a gripping portion, the drawing device being connected to the gripping portions and the abutment portion being shiftable in the longitudinal direction of the drawing device.

This embodiment allows jointing of two tubes aligned with one another and guarantees a tight drawing together of the joints.

Another embodiment of the present invention is suitably characterized in that the abutment portion has a socket for accommodating a part of a peripheral surface of a second tube whose longitudinal direction is transversely directed in relation to the first tube; and that the drawing device is in connection with the gripping portion and the second tube.

This embodiment of the present invention realizes a reliable and tight joint where the interconnected tubes make a right angle with one another.

Further advantages will be attained according to the present invention if the subject matter of the invention is also given one or more of the characterizing features as set forth in appended Claims 3 and 5-7.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In th e accompanying Drawings:

Fig. 1 is a central longitudinal section through a first embodiment intended for jointing two tubes aligned with one another; and

Fig. 2 is a central longitudinal section through a second embodiment intended for T-jointing of tubes.

DESCRIPTION OF PREFERRED EMBODIMENT

The tube connector illustrated in Fig. 1 is designed to give a tight jointing of two tubes aligned with one another so that the tubes are coaxial. In Fig. 1 , broken lines 1 intimate an end portion of a first tube. Interiorly in the end portion of this tube, there is disposed a gripping portion 2 which, in the illustrated position, has a substantially cylindrical outer surface. The gripping portion 2 partly accommodates an expander portion 3 which has a substantially frusto-conical circumferential surface 4. The thick end of the expander portion 3 is turned to face towards an abutment portion 5 which is in the form of a thick disk with parallel abutment surfaces 6 which, in a radial direction, i.e. in the transverse direction of the tube 1 , extend so far out that they are placed so as to prevent axial movement of the tube 1 shown by broken lines, in a direction to the left, and a corresponding movement in a direction to the right of a corresponding tube (not shown) engaging with the left-hand half of the tube connector in the Figure.

It will be apparent from the Drawing that there are provided, on either side of the abutment portion 5, identically designed gripping portions 2 and expander portions 3 so that the tube connector is thereby symmetrical. It should, however, be observed that, according to the invention, it is also possible to design the gripping portion and the expander portion on the one side of the abutment portion so that these have a different diameter, such that, as a result, the tube connector will be capable of jointing two tubes of different diameters. In such a case, the abutment portion 5 may naturally

have a conical or tapering circumferential surface so that there is thereby formed a gentle transition between the outer surfaces of the jointed tubes.

As was mentioned above, the gripping portion 2 has, in the position shown on the Drawing, a substantially cylindrical circumferential surface 4. However, this circumferential surface is provided with axially parallel depressions or grooves in which through slots (not shown) are disposed, from the open end 7 of the gripping portion axially parallel in a direction towards the endpiece 8. Preferably, these slots extend as good as right up to the endpiece 8.

It will further be apparent from the Drawing that the peripheral wall (or the axially directed fingers which are formed by the peripheral wall as a result of the presence of the longitudinal slots) is of greater thickness most proximal the endpiece 8 than is the case for the free ends 7. Hereby, the gripping portion 2 will have an interiorly conical surface which is substantially complementary to the conical circumferential surface 4 of the expander portion 3. This design of the gripping portion and expander portion entails that, when an axial movement is to be imparted to the gripping portion 2 towards the abutment portion 5, it will substantially expand cylindrically in order thereby to grasp the tube 1 from the inside. The axial movement of the gripping portion 2 also entails that the tube 1 will be entrained in the movement of the gripping portion until such time as the end surface of the tube 1 is brought into contact with the abutment surface 6 on the abutment portion.

It will also be apparent from the Drawing that the expander portion 3 has an end wall 9 of considerable thickness. The purpose of this end wall is to render the expander portion 3 incompressible in the radial direction as far as is possible. In order to save material in the expander portion, it is possible according to the invention to provide this portion with axially parallel and radially directed grooves so that also the circumferential surface 4 will be divided into band-shaped segments whose width may, for example, correspond to the width of the longitudinally directed fingers formed on the circumferential surface of the gripping portion 2 as a result of the presence of the slots.

On its endpiece 8, the gripping portion 2 has an exterior socket 10 for the non-rotary accommodation of a nut 11. This nut 11 cooperates with a longitudinally directed drawing device 12 which, at opposing ends, has threaded end portions 13 and 14, respectively, the threads being of opposite turn. In the central region, the drawing device has a thickened portion 15 which is not circular, for example, hexagonal, in order to achieve rotary engagement with the abutment portion 5 at the same time as this is axially shiftable along the thick centre portion.

In that the nuts 11 are non-rotatably connected with the gripping portions 2 and these are secured against rotation by friction against the inner surfaces in those tubes which are to be connected - or alternatively in that the tubes are initially held somewhat off centre or obliquely directed, the gripping portions 2 may be drawn toward one another by rotation of the abutment portion 5. In such instance, the mutually facing tube ends will be directed up and centred at the same time as they are drawn toward one another by frictional engagement with the circumferential surface of the gripping portions 2. Even if engagement is first established between the one tube end and the one gripping portion while the other tube end is still free in relation to its gripping portion, this does not imply that the tube joint will be untight, since the abutment portion 5 will be displaced in an axial direction until such time as the second tube end is also stabilized. When both of the tube ends abut against the abutment surfaces 6, continued rotation of the abutment portion 5 will result in a reliable radial grip between the gripping portions and the tubes, at the same time as the tubes are urged against the abutment portion until possible slipping occurs between one or both of the gripping portions and its associated tube, yet still with retained abutment between the tube ends and the abutment portion.

While, in Fig. 1 , the use of nuts 11 is shown in the sockets 10, it is obvious that the thread engagement between the drawing device 12 and both of the gripping portions 2 may be effected by other means, for example by casting of a threaded metal sleeve in the endpieces 8 or possibly by thread engagement direct in the material of the gripping portion 2.

In order to provide as precise centering as possible of the tubes which are to be connected, the endpieces 8 have a bore for accommodating the end portions of the drawing device 12, this bore and the drawing device having

close fit with one another. Correspondingly, the fit between the drawing device and a bore in the end wall 9 of the expander portion 3 is tight, but without offering any major friction against rotation of the drawing device.

In Fig. 1, the expander portion 3 has been shown with a relatively large calibre bore in the end facing the abutment portion 5. This implies that no guiding of the thick end of the expander portion 3 in a radial direction is achieved against the abutment portion 5. As an alternative to such a design, it is, however, possible to provide the thick central portion 15 of the drawing device with radially projecting annular formations which guide interiorly in the expander portion 3. For reasons which will be apparent below, it is unadvisable to substantially reduce the diameter of the bore.

In order to achieve the same guiding in the radial direction between the expander portion 3 and the abutment portion 5, it is possible to provide the expander portion 3 and the abutment portion 5 with engagement devices on their mutually facing surfaces which ensure a mutually radial position, at the same time as rotation is permitted. Such engagement devices may be designed in the form of annular, circumferential beads or flutes. Alternatively, the abutment portion 5 may naturally have a minor depression in its central region in which the expander portion 3 is accommodated.

It is apparent from the Drawing that the expander portion 3 has, at its thick end, a tapered portion 16 with a substantially radially projecting shoulder 17. For engagement with this should 17, the gripping portion 2 has, at the free end 7, inwardly directed projections 18 which, on mounting of the gripping portion on the expander portion by radial pretension inwards, snap down behind the shoulder 17 in order thereby to secure the relative axial position between the gripping portion and the expander portion, so that the expander portion will have an outer diameter which is but insignificantly less than the inner diameter of the tube 1 which is to be connected.

DESCRIPTION OF ALTERNATIVE EMBODIMENTS

Fig. 2 shows one alternative embodiment of the subject matter of the present invention, this embodiment being designed for T-jointing of tubes. This implies that two jointed tubes make substantially a right angle with one another.

In the embodiment according to Fig. 2, the abutment portion 5 is provided with a socket 19 which exteriorly connects around the second tube which is to be jointed with the first.

The designs of the gripping portion 2 and the expander portion 3 correspond to that described above with reference to Fig. 1 , for which reason the need for special tools for producing the two embodiments is reduced.

The abutment portion 5 is provided, on its side facing towards the expander portion 3, with a pin-shaped projection 20 which, with good fit, may be inserted (preferably with high friction) into the interior, relatively large bore with which the expander portion 3 is provided. Hereby, the abutment portion 5 and the expander portion 3 may be maintained positionally fixed in relation to one another at least during ongoing assembly work. In addition, there is a materials saving in the expander portion.

In order to obtain precise centering between the connected tubes, that bore through which the bolt 21 extends in the abutment portion 5 and the projection 20 has snug guiding fit in relation to the bolt.

On mounting of the tube connector according to Fig. 2, a first opening is drilled in the second tube (having its longitudinal axis at right angles to the plane of the Drawing in Fig. 2) for accommodating the shaft of the bolt 21. Diametrically opposite this opening, a second opening is made which is sufficiently large to allow passage of the head of the bolt 21 , which may suitably be of the so-called Allen type. Once these openings have been made in the second tube, the bolt is inserted through the tube so that the bolt head will be located interiorly in the tube while the socket 19 exteriorly surrounds a portion of the tube. In this position, the bolt also engages with the nut 11 without any retraction of the gripping portion 2 on the expander portion 3 having taken place. With the components mounted in this manner, the first tube 1 may then readily be shifted on the gripping portion, whereafter the bolt 21 is tightened and the first tube is grasped and drawn in toward the abutment surface 6. The opening in the second tube for passage of the bolt head may possibly be sealed with the aid of some suitable sealing means, for example a plastic plug or the like.

The present invention may be modified in that a transversely directed guide for the first tube 1 can be realized if the abutment portion 5 is provided with an annular projection which interiorly guides against the inner surface of the tube 1.

The subject matter of the present invention has been described in the foregoing as intended for the interconnection of cylindrical tubes. However, according to the present invention, the tube connector can be modified in such a manner that it is also capable of interconnecting, for instance, tubes of square cross section. In this case, the gripping portion 2 will naturally not be exteriorly cylindrical but will, instead, have a corresponding rectangular, parallelepipedic configuration. In this case, the above-mentioned slots are disposed at the corners of the parallelepiped possibly with additional slots on its sides. In a corresponding manner, the expander portion 3 will, naturally, not be made rotationally symmetrical but also this portion will be given rectangular wedge shape.

Further modifications of the present invention are conceivable without departing from the spirit and scope of the appended Claims.