Equipment for the sequential positioning, machining and finishing of the corners of window and door frames fashioned in plastic material, at a lateral work station

Abstract: The equipment (1) comprises a unidirectional feed system (10) by which plastic window/door frames (3) are conveyed with one flank flush against two longitudinally aligned fences (11, 12) positioned preceding and following a lateral work station (2) that serves primarily to remove beads of excess material from the corners (30) of the frames (3) and is equipped for the purpose with two traversing tool heads (25, 26), operating simultaneaously on the top and bottom faces of the frame; a terminal section of the first fence (11) and an initial section of the second fence (12) are fashioned as straight bars (4, 5) rotatable about respective vertical axes (41, 51) disposed on either side of the station (2), their movement accompanied by the transverse movement of a pin (23) associated with the work station, which draws the frame toward the tools. The traversing movement of the pin (23) is coordinated with the angular and linear movements transmitted to the frame (3) by the bars (4, 5) and the feed system (10), such that each corner (30) can be positioned correctly and in sequence in the machining area of the work station (2).

Description: The present invention relates to equipment by which the corners of window and door frames fashioned in plastic material are positioned in sequence for machining and finishing at a lateral automatic work station, a primary function of such a station being to remove the beads of excess plastic material that remain after the corners have been welded. Such an equipment is known from DE-A-3 447 113. The equipment disclosed is of the type comprising a system whereby frames are conveyed longitudinally and maintained in contact along one flank with a longitudinal entry fence that terminates in a first vertical stop coinciding with the beginning of the machining area of the lateral work station. Similarly, the frames register longitudinally with at least the initial section of a second, or exit fence, departing from a second vertical stop that coincides with the end of the machining area of the work station. The two stops thus allow the entry of one corner of a frame, positioned at an angle to the machining area of the lateral work station, while checking its approach from either side; the frame itself is drawn into the machining area by a catch pin capable of vertical movement in either direction and of reciprocating horizontally across the longitudinal direction in which the frames are conveyed through the equipment, so as to interfere cyclically with the successive frames by hooking onto each corner offered in turn for finishing and directing it toward the machining area. Conventional methods of manufacturing window and door fixtures in plastics include processes that permit of fabricating frames by welding together the relative rails and stiles, which are cut and joined at 45°. Given that the weld is effected by a localized application of heat to the material at the ends of the frame members, followed by mutual compression of the joined ends, the corners of the frame emerge from assembly exhibiting characteristic beads of fused material that must be removed subsequently by machining. The excess fused material is removed in a finishing step effected (together with other complementary machining operations) using equipment of the type in question, fitted with work stations consisting substantially in a plurality of tool units that are mounted to a bearing structure at various positions and angles in such a way as to engage the corners of a frame, arranged horizontally on a suitable table or bed, according to a prescribed sequence. In conventional work stations, the tool units are all positioned on one side of the frame offered for machining. Such conventional work stations are typified by a fundamental drawback, namely that the various tool units are positioned and orientated in space in such a manner as to execute a precise sequence of operations; thus, in order to execute a sequence of operations different from that prescribed, the need arises for adjustment to the physical components of the station. Equipment of the type thus outlined comprises a longitudinal feed system necessarily of overhead design, so as to permit of interfering effectively with the members of the frame disposed at right angles to the longitudinal fences. Only in this way is conventional equipment of the type in question able to operate. To distance each machined corner from the work station, in fact, direct interference with one of the two respective converging members is essential, otherwise unwanted sliding movement may occur between the frame and conveyor system. The overhead feed system comprises an interference mechanism capable of reciprocating movement both vertically, and horizontally in the feed direction of the frames. More particularly, systems of this type normally comprise an interference mechanism positioned in such a manner as to carry two vertical locating elements, rigidly associated with the bottom of the mechanism itself and thus made to follow its every movement in both the horizontal direction and the vertical direction. Such interference mechanisms engage in frontal contact with the cross members of the plastic frames which, proceeding thus along the equipment longitudinally, must also be maintained flush with the fences afforded by the equipment, as aforementioned. As the locating elements are simply offered to the cross members of the frames however, it can happen that the frames themselves rotate during forward movement and thus are not maintained faultlessly flush with the longitudinal fences. Furthermore, a system of this type is not suitable for smaller sizes of frames, being too large for the frame members to accommodate. Such conventional equipment is also beset by the notable drawback that the pin referred to above, forming part of the work station, is the one and only component used in positioning the corners of the frames, causing them to rotate about a fulcrum coinciding with the aforementioned first vertical stop, which marks the beginning of the machining area of the work station. Thus, if the proportions of the frame happen to be distinctly weighted in the longitudinal dimension, a solitary pin can be subject to bending stresses ultimately having an adverse effect on its operation. Moreover, the use of the pin in question as a sole means of rotating the frame corners into the machining area of the lateral work station dictates that the longitudinal feed system must necessarily operate by direct interference and in two directions as mentioned, given that the interference mechanism needs to displace the frames sequentially from one side of the work station to the other, positioning them exactly in such a way as will enable the pin to bring about successive rotations of the frame and permit thus of machining the corresponding corners. Accordingly, the object of the present invention is to overcome the drawbacks mentioned above. The stated object is fully realized by an equipment according to claim 1. Dependent claims 2-12 concern preferred embodiments of the invention. This equipment is not affected in any way by problems of stresses imposed on single working parts, which permits of utilizing a simple longitudinal feed system, unidirectional systems included, and which features a work station such as permits of executing an extensive range of machining sequences using a given selection of tool units, without the need for any adjustment of the physical component parts of the station, operating on both faces of a frame at one and the same time; such a station affords considerable flexibility, being able to execute machining sequences that can be reprogrammed swiftly and simply without the need for adjustments to physical component parts, and a drastic reduction in the time typically required to set up toolage when changing over from one sequence to another, with consequent benefits from the cost standpoint. In addition, with a preferred feed system according to the invention, notably simple in embodiment, any risk of the moving frame rotating or shifting from its prescribed path is totally eliminated, and the arrangement is wholly suitable for any typical size of fixture in general manufacture. Such a system also affords the advantage that the movement produced is substantially conventional, and that one of its two locating elements is simply rendered capable of movement by suitable means to the end that the mechanism may positively restrain each frame rather than merely entering into contact with it. Moreover, the system is proportioned and positioned in such a way as ensures its usefulness for any size and type of frame. Last, and by no means of least importance, the equipment is extremely simple and functional, given its level of performance. The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: fig 1 shows one part of the equipment disclosed, illustrated in perspective and with certain parts omitted better to reveal others; fig 2 illustrates a sequence of steps a, b, c, d, e and f corresponding to the various stages in the operation of the equipment disclosed; fig 3 illustrates a work station according to the present invention, in its entirety, with certain parts omitted better to reveal others; fig 4 is a schematic side elevation of the work station of fig 3; fig 5 is an enlarged view showing the detail of certain features of the work station of fig 3; fig 6 is a side elevation of the system by which window and door frames are fed longitudinally along the equipment disclosed, in which the greater part of the equipment is omitted to the end of giving greater emphasis to the longitudinal feed system; fig 7 illustrates a part of the equipment in plan, and a section of the longitudinal feed system taken through II-II in fig 6. With reference to the accompanying drawings, the equipment 1 disclosed comprises a feed system 10 by means of which window or door frames 3 fashioned in plastic material, supplied from a loading station, are conveyed longitudinally to a point level with a work station 2 designed essentially, though not exlusively, to remove beads 33 of excess material left by welding from each corner 30 of the frame 3. Such a station 2 is positioned to one side, in equipment of the type in question, the necessary opening lying between vertical stops 21 and 22, which in the case in point are embodied simply as vertical cylindrical elements that both guide the entry of the corner 30 of the frame to be machined and check its movement on each side. During the machining operation, the frames 3 are moved into a position angled in relation to the longitudinal direction, in such a way as permits of directing each corner into the opening of the lateral work station 2. The station is equipped with a pin 23 capable of vertical movement in the direction denoted F1, as well as reciprocating horizontally in the direction denoted F2 at right angles to the longitudinal direction in which the frames 3 are fed through the equipment 1. Vertical movement is rendered necessary by reason of the fact that the pin 23 must be raised and lowered, respectively, in order to register against each of the frames 3 from inside as discernible clearly in fig 1, and to recede from the dimensional compass of the frame 3 altogether, in certain conditions that will be made clear in due course. Transverse movement, on the other hand, is required clearly enough in order to position the pin 23 initially in the corner 30 of the frame 3, from the inside, prior to drawing the corner into the work station 2 at an angle, as will become clear in due course when the operation of other components combining to bring about this same situation is also described. More exactly, and with reference to fig 3, the equipment will be seen to comprise a work station 2 for machining the corners 30 of window and door frames 3 fashioned in plastic material, consisting substantially in a pair of parallel, motorized machined heads 25 and 26 supported by a bearing structure 6 and capable of guided movement, the one head 26 above the frame 3 and the other head 25 beneath; the frame 3 is supported by a suitable table 17 and occupies a horizontal plane 31. The bearing structure 6 is equipped with ways 16 by and along which the machine heads 25 and 26 are supported and capable of traversing horizontally, parallel to the plane 31 occupied by the frames 3. In a preferred embodiment, illustrated in figs 4 and 5, the horizontal ways 16 are of a type with rolling elements 27, whilst the movement of the heads 25 and 26 proper is generated by conventional mechanisms 13 of lead screw-and-nut embodiment driven by respective motors 14. The machine head denoted 25, located beneath the frame 3 in fig 3, supports and guides a plurality of tool units 8 disposed parallel one with another and capable of traversing independently toward the frame 3 so as to perform the various machining operations for which they are specifically designed (e.g. drilling, surface finishing, or positioning operations as in the case of the pin 23). In contrast to the head 25 positioned preferably below the frame 3, to which the corresponding tool units 8 are mounted direct, the tool units 8 of the top machine head 26, likewise capable of traversing individually in a direction normal to the plane 31 occupied by the frames, are mounted to a motorized slide 9 carried by the head on vertical ways 15. Supported in this manner by the bearing structure 6, the motorized slide 9 is capable of traversing in a direction normal to the plane 31 occupied by a frame 3 currently being machined. Likewise in a preferred embodiment, the slide 9 will be set in motion by a lead screw-and-nut type mechanism 13 driven by a respective motor 14. Similarly, for preference, the vertical ways 15 incorporate rolling elements. The work station 2 also comprises programmable control means 7, preferably numerical, by which the movement of the machine heads 25 and 26 and the relative tool units 8 is suitably synchronized and governed. For example, by piloting the horizontal traverse of the machine head 26 uppermost and the vertical traverse of its motorized slide 9, such programmable means 7 enable a given tool unit 8 to describe a selected and previously programmed trajectory within a plane normal to the plane 31 occupied by the frame 3, so that a simple variation of the machining program allows weldment beads of differing size and shape to be removed from the frame corners 30. The equipment 1 is provided further with a first longitudinal entry fence 11, terminating at the first vertical stop 21, and a second longitudinal exit fence 12 departing from the second vertical stop 22. The longitudinal feed system 10 will keep the frames 3 flush against these same longitudinal fences 11 and 12 during their progress along the feed path. A feed system 10 preferred for this same purpose is shown in figs 6 and 7, and would be used in conjunction with equipment 1 having a plain feed table 100, for example consisting in longitudinal rails 101 and transverse supports 102. The system 10 in question is of the type comprising an overhead interference mechanism 60 suspended above the table 100 along which the frames 3 are conveyed. The interference mechanism 60 is capable thus of vertical movement in either direction F3, and likewise of horizontal movement F4 back and forth along the direction followed by the frames 3. To advantage, the feed system 10 comprises a first locating element 61 vertically disposed and rigidly associated with the interference mechanism 60, and a second locating element 61b capable of movement between a first, at-rest position, shown in fig 6, and a second position, facing the first element, whereby a cross member 3b of the single frame 3 is restrained from either side (see fig 7 and figs 2c, 2d and 2f). Means 70 will therefore be provided by which to bring about the movement of the second locating element 61b, consisting in a simple fluid power cylinder 71 in the example illustrated, which are designed to apply the restraint in conjunction with the element 61 facing, synchronously with the operating steps of the longitudinal equipment 1 as a whole. It will be seen also that the dimensions of the locating elements 61 and 61b, to advantage, are kept strictly within a longitudinal band R that is separated from the longitudinal fences 11 and 12 by a distance d1 greater than or equal to a maximum transverse dimension of the longitudinal member 3a of a frame 3 of larger dimensions (shown in fig 7), and compassed on the side opposite by a boundary L located at a distance from the fences 11 and 12 less than or equal to the position occupied by the farthest longitudinal member 3a' of a frame 3 of smaller dimensions. Thus, the system 10 is sure to operate with equal efficiency on any given frame, regardless of size. The operation of such a mechanism 60 is plain to see, and requires no detailed explanation. Advantageously, equipment according to the present invention is able to operate with a longitudinal feed system 10 of less sophisticated embodiment; a unidirectional, transversely biased type of system as shown in fig 1, for example, is sufficient for the purpose in hand. Such a system 10 comprises conveyor belts 62 that turn in one direction only, denoted F5, and rollers 63 that rotate continuously in the direction denoted F6. The sufficiency of the unidirectional motion will be demonstrated in due course. A special feature of the equipment disclosed, which allows the use of a conventional feed system 10 and is free from the drawbacks described at the outset, consists in the fact that the terminal section of the first longitudinal fence 11 and an initial section equal in length of the second longitudinal fence 12 are embodied as two respective straight bars 4 and 5 rotatable about corresponding vertical axes 41 and 51, preferably coinciding with the axes of the vertical stops 21 and 22. The bars 4 and 5 are capable of movement at different moments, as will become clear in due course, from a first limit position of alignment with the fences 11 and 12 to a second limit position, rotated to an angle of 45° anticlockwise, in the case of the one bar 4, and clockwise in the case of the other bar 5. One only of the two bars 4 and 5, for example that denoted 4 in the drawings, is also provided with restraining means 42 by which the member of the frame currently positioned against the fence is caused to rotate as one with the bar 4 in both directions. Moreover, it is preferred that the frame member in question be allowed to slide longitudinally in relation to the bar so as to adapt in the best manner possible, when diverted from its position of freely advancing motion in the longitudinal direction, to the angled position in which its corners 30 are machined, as will become clear in due course when the operation of the equipment will be described. Given, in practice, that the straight bars 4 and 5 are rotated through an unvarying angle during the course of operation, such movement can be brought about to advantage by means of corresponding fluid power cylinders 54 and 55. As regards restraining means 42, these are embodied to best advantage as a simple hold-down clamp 43 associated permanently with the bar 4, of which the rod 44 carries an interference element 45. Such an element will be preferably of L profile, as shown in fig 1, such that the clamp 43 can be operated in two distinct vertical positions: a first, with the interference element 45 registering only against the inside face of the frame member 3a (which thus remains free to slide longitudinally), and a second in which both the inside face and the top face are engaged, in such a way that the frame 3 will be held secure by the clamp 43 during the machining operation effected on the corners 30. At all events, the equipment might also incorporate a further clamp 49, mounted to the second vertical stop 22 for example, serving to secure the frame 3 when the relative corner 30 is being machined. In this instance, needless to say, the clamp 43 first mentioned could be operated with the interference element 45 assuming one vertical working position only. The operation of the equipment disclosed appears abundantly clear from fig 2, which illustrates the different steps and the movements of the various component parts characteristic of the invention. In steps a, b, c, d, e and f of fig 2, the position of those parts invested with vertical movement is denoted by a dot (=) when raised and by a cross (x) when lowered. Fig 2a shows a frame 3 that has been conveyed by the transversely biased feed system 10 to a point level with the work station 2 and positioned exactly in such a way that the pin 23, traversing across in the direction denoted F2', can engage a first corner 30a. Clearly, when moving in the direction denoted F2', the pin 23 will be in the lowered position denoted by the arrow F1 (fig 1), and raised thereafter on arrival at the position of fig 2a, as illustrated. The restraining means 42 associated with the bar 4 will be in the raised position, naturally enough, thus allowing passage of the frame 3. The instant the situation of fig 2a has occurred, the restraining means 42 are lowered, the interference element 45 remaining initially in the partly raised position in such a way that the frame 3 is able to settle into the angled position of fig 2b as the bar 4 rotates in the direction denoted F8 from its longitudinally aligned position to an angle of 45°. At the same time, the pin 23 retracts to its former position, traversing toward the work station 2 in the direction denoted F2''. Thus, the frame 3 will be positioned correctly, regardless of its overall dimensions, given that the force contributed by the bar 4 is sufficient to relieve the pin 23 of any stress-related mechanical overload. Once this first corner 30a has been machined in the work station 2, the bar 4 rotates in the direction denoted F9 to regain its position of longitudinal alignment (see fig 2c), straightening the frame 3 from the angled position and freeing the restrained member 3a. As the bar 4 is rotated, the pin 23 will again traverse forward, underneath the frame 3, in the direction denoted F2'. In this situation, the frame is entirely free to proceed in the direction denoted F5 toward the exact position of fig 2d, at which stage the configuration is essentially as in fig 2a but with the frame shifted toward the exit, such that the pin 23 can engage the corner 30b at the end opposite to the previous corner 30a and on the same side, as will be clear from fig 2d. Now, the second bar 5 will rotate in the direction denoted F10 with the pin 23 again being caused to retract, in such a way as to position the frame 3 correctly at an angle and thus permit of machining the second corner 30b (fig 2e). The first bar 4 also contributes to this step by rotating once again in the direction denoted F8 toward the angled position, whereupon the restraining means 42 will operate. With this corner 30b also machined, the bars 4 and 5 again return to the longitudinally aligned position whilst the pin 23 extends from the machining area of the word station 2; at this point the situation will be similar to that indicated by the phantom line of fig 2c, whereupon the cycle of figs 2d, 2e and 2f is repeated until all the four corners of the frame have been machined. This accomplished, the frame 3 will be transferred to an exit station and ejected, vacating the table for a successive frame 3. During the various machining steps effected on each successive corner, the restraining means 42 will be made to descend to the vertical position in which the frame 3 is fully clamped, except in the event that the equipment is fitted with a second clamp 49 as illustrated in fig 1. Whatever the ultimate embodiment, the sequence of steps thus described clearly reflects an operating procedure that is based on the notion of utilizing just one straight bar 4, rotatable through a given angle between two limit positions and equipped with means 42 such as will restrain one member of a frame 3 while allowing it to slide freely, at least when necessary.

Claims: Equipment for positioning the corners of plastic window and door frames in sequence, to be machined and finished at a lateral station serving primarily to remove beads of excess fused material from each corner automatically, of the type that comprises a longitudinal feed system (10) by which frames (3) lying in a horizontal plane are conveyed in a longitudinal direction and held in flush contact along one flank at least with a first entry fence (11), longitudinally disposed and terminating at a first vertical stop (21) marking the beginning of the machining area of the work station (2), and with at least the initial section of a second exit fence (12) longitudinally disposed and departing from a second vertical stop (22) that marks the end of the machining area of the work station (2), wherein the stops (21, 22) serve to accommodate the entry of the corners (30) of the frame (3) when offered at an angle to the machining area of the work station (2) while checking the corresponding entry movement from either side, and the frames are positioned at the work station by a pin (23) capable of vertical movement in either direction and of reciprocating horizontally through a path transverse to the longitudinal direction in which the frames are fed through the equipment (1), in such a way as to engage the frame (3) cyclically by interfering with the relative corner (30) to be machined and drawing it into the machining area, characterized in that a terminal section of the longitudinally disposed first fence (11) and an initial section of the longitudinally disposed second fence (12) are embodied as two respective straight bars (4, 5) rotatable about relative vertical axes (41, 51) coinciding respectively with the first and second vertical stops (21, 22), and capable of movement both together and independently between a position of alignment with the first and second fences (11, 12) and an angled limit position in which each bar (4, 5) is rotated through 45° from the position of alignment and two adjacent corresponding members of a frame (3) are restrained at the same angle; in that it also comprises restraining means (42) associated with one only of the two bars (4, 5), by which the frame (3) is straightened from the angled position, in which a given corner (30) is machined, to resume a position such as enable its motion in the longitudinal direction, in such a way that each frame (3) is manoeuvred, sequentially and by means of the longitudinal feed system (10), from a first position in which the pin (23) interferes with and engages a first corner (30), passing through an intermediate position in which the frame (3) is disposed at an angle to enable machining of the first corner (30), to a second position in which the pin (23) engages a second corner (30) opposite from the first on the same side; and in that transverse movement of the pin (23) is coordinated with the rotational movements transmitted by the bars (4, 5) to each frame (3). Equipment as in claim 1, wherein the longitudinal feed system (10) is unidirectional. Equipment as in claim 1, wherein each straight bar (4, 5) is rotatably associated with the respective vertical stop (21, 22) in direct manner. Equipment as in claim 1, wherein restraining means (42) consist in a hold-down clamp (43) permanently associated with the bar (4), of which the rod (44) carries an interference element (45) registering at least with the innermost face of the member of a frame (3) offered to the bar. Equipment as in claim 3, wherein each bar (4, 5) is caused to rotate by means of a corresponding fluid power cylinder (54, 55). Equipment as in claim 4, wherein the interference element (45) of the hold-down clamp (43) is able to occupy a first, more elevated working position in which the interference element (45) registers exclusively with the innermost face of the member of a frame (3) offered to the bar, and a second, lower working position in which the interference element (45) impinges firmly on the uppermost face of the same member of the frame (3). Equipment as in claim 1, comprising at least one clamp (49) associated with one of the two vertical stops (21, 22), designed to secure each frame (3) while one of its corners (30) is machined. Equipment as in claim 1, wherein the lateral work station (2) comprises: a pair of motorized machine heads (25, 26) mounted to parallel ways (16) associated with a bearing structure (6), occupying respective positions on opposite sides of a plane (31) occupied by the frame (3) to be machined, and traversed by drive means (13) in relation to the bearing structure (5) through a direction parallel with the plane (31) occupied by the frame (3); a plurality of tool units (8) associated with each of the machine heads (25, 26), disposed adjacent, parallel one with another and capable of traversing guided in a direction normal to the plane (31) occupied by the frame (3); programmable control means (7) enabling timed coordination of the movement of the machine heads (25, 26) and the tool units (8). Equipment as in claim 8, wherein the tool units (8) are able to traverse independently of one another in a direction normal to the plane (31) occupied by the frame (3). Equipment as in claim 8, wherein at least one machine head (26) of the pair carries a motorized slide (9) interconnecting the head and the relative plurality of tool units (8) and able to traverse in a direction normal to the plane (31) occupied by the frame (3). Equipment as in claim 1, wherein the longitudinal feed system (10) is of the type consisting in an overhead interference mechanism (60) capable of vertical movement in either direction (F3) and of horizontal movement in either direction (F4) along the path followed by the frames (3), and comprises a first locating element (61) rigidly associated with the interference mechanism (60) and vertically disposed, a second locating element (61b) capable of movement from an at-rest position to an active position, facing the first element (61), whereby a cross member (3b) of each frame (3) is restrained from either side by the two locating elements, and means (70) by which to bring about the movement of the second locating element (61b) in such a way that application of the restraint is coordinated with the operating steps of the equipment (1). Equipment as in claim 11, wherein the transverse dimension of the locating elements (61, 61b) is contained within a longitudinal band (R) separated on the one side from the longitudinal fences (11, 12) by a distance (d1) greater than or equal to the maximum transverse dimension of the longitudinal member (3a) of a relatively large size frame (3), and compassed on the side opposite by a boundary (L) located at a distance from the longitudinal fences (11, 12), less than or equal to that of the farthest longitudinal member (3a') of a relatively small size frame (3), in such a way that the longitudinal feed system (10) is able to operate with equal efficiency on frames (3) of any given size.

Inventors: PASQUINI LUCIANO, PASQUINI, LUCIANO
Applicants: UNIVAL SRL, UNIVAL S.R.L.
Application year: 1990
Main classification: B23Q16
IPC codes: B23Q3, B29C37, B23Q7