A device for fitting seals automatically into the seating grooves of thermoplastic pipe sockets

Abstract: A device (16) for seating seals (6) automatically in the grooves (14) afforded by the sockets (3) of plastic pipes (4) comprises a straight tubular element (1) offered immediately adjacent to and in alignment with the pipe socket (3) and serving to support and position a seal (6) of outer diameter greater than the internal diameter of the socket, a plunger (7) capable of sliding movement internally both of the tubular element and of the socket, by which a seal positioned in the tubular element is inserted into the groove (14), and actuators (10) by which the plunger is reciprocated automatically.

Description: The invention concerns a device for automatically introducing seals in seating grooves of thermoplastic pipe sockets, of the type comprising: a straight tubular element adjacent to and aligned with the pipe socket, having an internal cavity accessible through a peripheral opening, the said cavity having edges, between which a seal is supported transversally to the axis of the socket, resting against an internal wall of the cavity; a plunger able to slide internally to the tubular element and the socket, having a front end equipped with an angled frontal surface and having a transversal section which interferes geometrically with the seal supported by the tubular element; actuating means by which the plunger is moved parallel to the axis of the tubular element and socket, describing a course comprising a first stage in which the seal contacts with the frontal surface and is gradually inserted into the cavity of the tubular element, assuming an inclined lie, a second stage in which the seal is transferred forwards in an inclined position up until a point where its most advanced part locates in the seating groove, a third and final stage in which the front end of the seal is retained in the seating and the front end of the plunger gradually crosses the seal, inserting a progressively increasing portion into the seating, the said third phase being completed at the limit position wherein the frontal surface of the front end of the plunger has entirely passed across the seating. To realise pipelines for fluids thermoplastic pipes are frequently used, which are assembled one to another at their ends, the ends being conformed as sockets internally provided with seating grooves in which seals are inserted to seal the fluid transported. The seals, characteristically annular in shape, are inserted into the tube during the socket formation phase by using known-type devices, quite varied in construction, most of which work by exploiting the elasticity of the material constituting the seal. The above-mentioned devices essentially perform the following phases: an elastic compression phase of the seal, impressing on it a smaller than normal annular configuration; a seal introducing phase, with the seal still in its smaller than normal configuration; a seal insertion phase into the seating, after a correct positioning of the seal with respect to the seating, and a consequent re-expansion and permanent insertion of the seal in the socket. Known-type devices of the above-mentioned type, independently of their specific constructional and use characteristics, which are more or less advantageous according to different realisations, all suffer from the fundamental disadvantage of not permitting the introduction of seals made of non-elastic materials into the pipes. Thus with these devices it is not possible to use seals in polypropylene plastic or seals in elastic material equipped with plastic strengthening rings. This fundamental drawback is obviated by a device, also of known type, corresponding to the preamble of claim 1 (Document EP-A-137907) which permits the introduction of thermoplastic seal pipes into the sealing grooves, which pipes can be made of any material comprising plastic materials or seals made in elastic materials but equipped with plastic strengthening rings. This last device, differently from the previous ones, has the advantage of permitting total freedom from the necessity to use elastic materials, allowing the housing of seals made with more suitable materials also with regard to the physical-chemical nature of the transported fluids. It does, however, exhibit the fundamental drawback of not permitting, through its monolithic plunger, a correct and total introduction of the seals in smaller-length sockets, and/or sockets immediately followed by curved tracts of pipeline with narrow section. This drawback, quite serious also in the case of elastic seals, which maintain a certain self-adapting ability insider the seating groove deriving from their elasticity, is critical for plastic seals, or seal made in stiffened plastic materials. A second drawback of the known-type device is further constituted by the fact that, concerning the structure of the means aimed at engaging the seal, transferring it and inserting a part of it in the seating before the seating is crossed by the plunger, the device has means comprising a rotary-slidable rod in a cylindrical seating made inthe body of the plunger, provided with a shaped end which shape strictly depends on the geometry of the seal, the shape of the seating the seal is to be inserted in, as well as the sizes of the preceding. The aim of the present invention is thus to obviate the above-mentioned drawbacks. The invention, as it is characterised in the claims, reaches the said aim by providing a device able to permit of automatically introducing seals made of any kind of material in the seating grooves of thermoplastic pipes having small-length sockets and/or grooves situated close to narrowed sections of the pipe. The invention reaches the said aim by means of a plunger comprising at least two component parts which are reciprocally slidable along a median plane parallel to the trajectory of the plunger on the activation of actuating means, wherein the said component parts are moved independently in such a way as to minimise the axial mass of the front end of the plunger internally to the socket. The invention is further provided with means to engage, transfer and subsequently locate a part of the seal in the seating offered by the socket, comprising a lever situtated at a most projecting part of the frontal surface of the plunger, associated to the plunger in such a way as to be slidably oscillating in a parallel plane to the socket axis and longitudinally slidable internally of the plunger seating, interacting with the seal by means of an end of the lever in a way which is automatically adaptable to the shape, dimensions and type of material of the seal. Devices realised according to the invention thus have the advantages of permitting: very cost-effective realisations when considering the range of work offered by them; a great versatility of use, since one device alone, even operating on medium-sized diameters, can be used with abny geometry of the seal section; the realisation of devices completely independently of the length and shape of the socket, simply by means of realising a characteristic operative element in dismountable and independently movable parts. The invention will now be described in detail, by way of example, with the aid of the accompanying drawing, fig. 1, in which the device is illustrated in a general side elevation with certain parts cut away better to reveal others. With reference to the drawing, 16 denotes a device by means of which to fit seals 6 automatically into the seating grooves 14 afforded by the sockets 3 of thermoplastic pipes 4. Such a device 16 essentially comprises: a straight tubular element 1 offered immediately adjacent to and in alignment with the socket 3 of a pipe 4 and serving to support a seal 6 of external diameter greater than the internal diameter of the socket 3; a plunger 7 capable of sliding movement within both the tubular element 1 and the socket 3, by which a seal 6 supported in the tubular element 1 is inserted into the seating groove 14; means 10 by which to actuate the plunger 7 automatically. The tubular element 1 affords an internal cavity 2 with a cylindrical wall 20 of diameter identical to that of the socket 3, which in addition to its two open ends 5 is also accessible through a peripheral slot 11 of which the two edges 12 are designed to support a single seal 6 standing upright in a plane transverse to the axis 3a of the socket and resting on the internal wall 20 of the cavity 2 at bottom. The forwardmost end 8 of the plunger 7 directed toward the tubular element 1 presents an angled frontal surface 9; moreover, the cross section of the forwardmost end 8 is shaped in such a way as to interfere geometrically with a seal 6 occupying the slot 11 of the tubular element. In the preferred embodiment of the device 16 shown in the accompanying drawing, the forwardmost end 8 of the plunger 7 is cylindrical and exhibits an external diameter identical to the diameter of the cavity 2, such that on insertion of the plunger 7 into the cavity, this same cylindrical end 8 will physically encounter a seal 6 currently occupying the slot 11. The plunger 7, actuated by automatic means 10 as aforementioned, reciprocates along a rectilinear trajectory coinciding substantially with the axis of alignment 3a between the tubular element 1 and the socket 3. In a preferred embodiment, such automatic actuator means 10 might be embodied simply as pneumatic cylinders, operated in conjunction with parallel guide rods 10a by which any unwarranted angular movement of the plunger 7 is prevented. The operation of the device 16 described thus far will best be appreciated by observing the steps which take place during passage of the plunger 7 along its trajectory, departing from an initial position, shown by the bold line of the drawing, in which the plunger 7 is positioned in alignment with but externally of the tubular element 1. In a first stage of its forward stroke, the plunger 7 is moved away from the initial position toward the tubular element 1, and enters the cavity 2. On covering a short distance internally of the cavity 2, the angled surface 9 will impinge on the seal 6 and force it gradually forward until fully inside the cavity 2; needless to say, the seal 6 must necessarily assume an angled position in order to enable its insertion into the cavity 2, given its greater diametral dimensions. Thereafter, with the plunger 7 continuing to advance, the seal 6 is forced further to the point where its leading edge encounters the profile of the seating groove 14 afforded by the socket 3. This same leading edge of the seal 6 now locates in the groove 14, thereby creating an obstacle to further translatory motion, with the result that the forwardmost end 8 of the still advancing plunger 7 begins to pass through the seal 6 and thus locks the arrested leading edge forcibly in the groove 14. As the plunger 7 drives further forward and the cylindrical end 8 continues to force through the seal 6, the seal itself will become seated to a progressively greater degree in the groove 14 and its angle of inclination will grow less and less pronounced. In effect, while the forwardmost end 8 of the plunger 7 exerts a frontal thrust, the lateral surface denoted 20b invests the seal 6 tangentially and works it by degrees into the groove 14. Full insertion of the seal is accomplished once the angled surface 9 has passed completely beyond the groove 14 and the seal 6 has been worked completely into the relative profile. In a more advantageous and comprehensive embodiment of the device, the plunger 7 comprises a lever 13, accommodated internally of a longitudinal chase 15 formed in the surface of the plunger and extending back from the farthest extremity of the forwardmost end 8, which is anchored to the plunger 7 itself in such a manner as to permit both of rotation about a pivot 21 and of sliding longitudinally in relation to the plunger 7. The lever 13 is embodied with one end 13a formed as a seating element, and with its remaining end 13b connected to means 17 by which the lever itself is actuated prior to actuation of the plunger 7 as a whole. These further actuator means 17 enable the lever 13 both to pivot and to traverse in relation to the plunger 7 in such a way as to engage the seal 6 during the traverse movement and carry it forward by the leading edge through the tubular element 1, and by pivoting thereafter, to press the leading edge into the groove 14 in readiness for the full seating action performed by the plunger 7. It will be clear enough that the adoption of the lever 13 provides added positioning stability when locating the leading edge of the seal 6 in the groove 14 during this initial part of the seating operation. To enable the insertion of seals 6 in sockets 3 of reduced axial dimensions, such as those afforded by pipes 4 incorporating bends, the plunger 7 can be embodied to advantage in a plurality of separable component section, and in the particular example of fig 1, in two sections 7S and 7I which combine to exhibit the same external geometry as that of a one-piece plunger 7, but are slidable in relation to one another along a plane disposed parallel to the trajectory of the plunger 7. The component sections 7S and 7I can therefore be actuated independently in such a way as to perform all the functions of the plunger 7 described thus far, while requiring a minimum of axial clearance internally of the socket 3. In this instance, the two component sections 7S and 7I will be operated independently by the automatic actuator means 10, in such a way that the section 7S farthest removed from the lever 13 can be made to continue forward after movement of the other section 7I has already ceased.

Claims: A device for automatically introducing seals in grooved seatings provided with thermoplastic pipe sockets, comprising: a straight tubular element (1) adjacent to and aligned with the pipe socket (3), aimed at supporting a seal (6) having an external diameter greater than an internal diameter of the socket (3), the tubular element (1) having an internal cavity (2) accessible through a peripheral opening (11) with edges (12) between which edges (12) the seal (6) is supported transversally to an axis (3a) of the socket (3) resting against an internal wall (20) of the cavity (2); a plunger (7) able to slide internally to the tubular element (1) and the socket (3), having a front end (8) equipped with an angled frontal surface (9) and having a transversal section which interferes geometrically with the seal (6) supported by the tubular element (1); actuating means (10, 10a) by which the plunger (7) is moved parallel to the axis (3a) of the tubular element (1) and socket (3), describing a course comprising a first stage in which the seal (6) contacts with the frontal surface (9) and is gradually inserted into the cavity (2) of the tubular element (1), assuming an inclined lie, a second stage in which the seal (6) is transferred forwards in an inclined position up until a point where its most advanced part locates in the seating groove (14), a third and final stage in which the front end of the seal (6) is retained in the seating (14) and the front end of the plunger (7) gradually crosses the seal (6), inserting a progressively increasing portion into the seating (14), the said third phase being completed at the limit position wherein the frontal surface (8) of the front end of the plunger (7) has entirely passed across the seating (14), characterised in that the said plunger (7) comprises at least two component parts (7s, 7i) which are reciprocally slidable along a median plane parallel to a trajectory of the plunger (7), moved by the actuating means (10, 10a), in such a way as to minimise the axial mass at the front end (8) of the plunger (7) inside the socket (3). A device as in claim 1, comprising means to engage, transfer and subsequently locate a part of the seal (6) in the seating (14) offered by the socket (3), which means are contained in a longitudinal and peripheral seating (15) made in the plunger (7), characterised in that the means comprise a lever (13) situated in a most projecting part of the frontal surface (9) of the plunger (7) and constrained to the plunger (7) so as to be rotatably oscillating in a plane containing the axis (3a) and longitudinally slidable internally of the seating (15). A device, as in claim 1, characterised in that the said component parts (7s, 7i) have mutually different dimensions. A device as in claim 1, characterised in that the said component parts (7s, 7i) of the plunger (7) have differently inclined frontal surfaces (9) with respect to the axis (3a) of the said cavity (2) of the tubular element (1). A device as in claim 4, characterised in that the said frontal surfaces (9) of the said component parts (7s, 7i) exhibit projections which are reciprocally superposable on the axis (3a) of the said cavity (2).

Inventors: SAVIOLI LEOPOLDO, SAVIOLI, LEOPOLDO
Applicants: SICA SPA, S.I.C.A. SERRANDE INFISSI CARPENTERIA ATTREZZATURA S.P.A.
Application year: 1990
Main classification: B23P19
IPC codes: F16L21, B23P19