Bar feeder

Abstract: A bar feeder for machine tools, comprising at least a first and a second carriages (12) for bearing the bars (13), said carriages (12) being movable along guide rods (11) which are supported at the ends so as to freely oscillate with the carriages (12) and the bar (13). The guide rods (11) bear the carriages (12) by means of sliding bushes (19) which maintain the bars (13) parallel and at a suitable distance from one another during oscillations. A supplementary bar guide (28) comprising a bar pushing member (30) is movable supported between a position coaxially arranged to the supporting carriages (12) and a side or underlying position.

Description: This invention relates to a bar feeder for machine tools, in particular for lathes and similar machines, of the type in which the bars are supported in a rotating manner and are guided towards the machine tool by carriages moving along longitudinal guides. In feeders of the aforementioned type there is the problem of reducing the high level of noise caused by the carriages jolting against the guides due to the vibrations generated by the bars when rotating rapidly. Such a feeder is disclosed in DE-A-3634364 on which is based the preamble of claim 1 in which guide rods are prevented to move by resting for the entire length on grooved supporting beds. In the past, attempts have been also made to at least partially eliminate this inconvenience by fixing the guides rigidly with a material suitable for partially damping or absorbing the vibrations, and providing the sliding runners of the carriages with a similar material. Nevertheless the results achieved, even if they did enable the noise of the bar feeders of the aforementioned type to be reduced in part, are not completely satisfactory since the vibrations generated by the rotation of offset parts of the bars are in any case transmitted by the carriages to the slide guides and by the latter to the support structure, still causing a considerable amount of noise. An object of this invention is to provide a bar feeder, of the aforementioned type, by means of which it is possible to substantially reduce the noise caused by the vibrations generated by the bars during rapid rotation, at the same time enabling the bars to be guided gently and safely to the mandrel of the machine tool. A further object of this invention is to provide a bar feeder as stated above, having auxiliary bar guide means for an additional push member and/or for lengths of rods, or for elongated parts having relatively small longitudinal dimensions, for example for shafts or others which have to undergo head machining, for which guiding in the end section of the feeder may be less critical compared to bars of greater dimensions. From tests carried out it was found that a considerable noise reduction is obtained in a bar feeder comprising the features of claim 1; dependant claims define particular embodiments of the invention. The bar feeder according to this invention and some of its characteristics are to be illustrated in greater detail as follows with reference to the enclosed drawings, where: Fig. 1 is a top view of a feeder according to the invention; Fig. 2 is a side view of the feeder of Fig. 1, with some parts removed; Fig. 3 is an end view of the feeder, along the line 3-3 of Fig. 2; Fig. 4 shows an enlarged detail made along the line 4-4 of Fig. 2; Fig. 5 shows an enlarged sectional view of a bar bearing carriage; Fig. 6 is a cross sectional view showing a further solution of an additional movable guide device comprising a double pushing device; Fig. 7 is a cross sectional view of a further embodiment of the bar feeder according to this invention; Fig. 8 is a top view of the devices for guiding and pushing the bars shown in Fig. 7. Fig. 1 shows an overall view of a bar feeder according to the invention. The feeder comprises a support structure 10 for three guide rods 11 positioned at the apices of a triangle, only two being shown in Fig. 1, and along which slide two carriages 12 for supporting a bar 13 which has to be fed to a machine tool mandrel. The guide rods 11 for the carriages are suitably fixed to the structure 10 in order to enable them to oscillate freely together with the same carriages. This can be achieved, as shown for example in Fig. 1, by fixing the guide rod 11 only at their ends to two backing plates 14, Fig. 3, bolted to the structure or frame 10 of the feeder. One of the plates 14, and in particular the plate shown in Fig. 3, which is on that side of the feeder turned towards the mandrel of the machine tool, is provided with a bar guiding means comprising a bush member 15 of elastomeric material, having a low frictional coefficient, supported in a rotating manner by a bearing 16 which is in turn fixed to the plate 14 by the interposition of a rubber ring member 17 or another part suitable for absorbing vibrations. In order to enable the carriages 12 to run along the guide rods 11 and to freely oscillate together with the rods themselves, maintaining the latter constantly spaced apart from each other with a disposition substantially parallel to the longitudinal axis of the structure 10, or the axis of the mandrel of the machine tool, each carriage comprises a central body 18, for example circular in shape, to whose periphery sliding sleeve members 19 are fixed, one for each of the guides rods ll. As shown in figure 5 the body 18 of each carriage 12 comprises a central bush member 20 having the same diameter or cross-dimensions and shape of the bar 13, which bush 20 is interchangeably placed in an intermediate bush member 21 in turn supported in a rotating manner by bearings 22 and by a ring 23 fixed to the body 18 of the carriage by the interposition of an annular pad 24 in elastomeric material, for damping and deadening the vibrations. The bush 20 of the rear carriage 12 differs from the bush 20 of the front carriage in that it protrudes or extends to the rear of the body 18, with an annular cup member 20a having a reduced aperture or hole 20b to enable the bar 13 to be pushed forwards by the carriage and at the same time to insert a supplementary push member 30, having a diameter smaller than that of the bar. The guide sleeves 19 of each carriage run without play along the guide rods 11 in such a way that each carriage unit 12 and the guide rods 11 form a single assembly capable of oscillating, without jolts or collisions occurring between the parts which otherwise might cause noise. In this way the vibrations generated by a possible eccentric rotation of a bar 13 or part of it, are transmitted by the carriages 12 to the guide rods 11 which, due to their possibility to freely oscillate in relation to the support structure 10, completely absorb said vibrations. In this way an extremely quiet feeder structure is obtained which at the same time ensures gentle and safe guiding of the carriages since the latter act on the guide bars 11 to guarantee and maintain their parallel disposition. The carriages 12 of the feeder are moved independently along the guide bars 11, for example by a respective chain control means illustrated schematically by 25 in Fig. 2. Said control means substantially comprises an endless chain 26 having one side fixed to the carriage 12 and driven by an electric motor 27. According to a further characteristic of this invention the bar feeder comprises a supplementary movable guide device provided with a push member which intervenes to move the bar 13 forward towards the interior of the machine tool mandrel, in the final portion of its forward stroke; if required, this guide 28 may be used for supporting and introducing into the carriages 12, when the latter are completely forward as shown in Fig. 1, a shorter length of rod or elongated parts which have to be head machined, for example a shaft or similar. This supplementary guide, indicated overall by 28 in Fig. 1 comprises a tubular member 29 having a longitudinal slot which extends parallel to the bar 13 to be fed, in which a pushing member 30 is longitudinally movable inside said tubular part. The tubular member 29 is supported by a pair of side arms 31 fixed to a rotational axis 32; the axis 32 is carried in a rotating manner by the structure 10 and is connected to a toothed wheel 33 (Fig. 4) which engages with a rack 34 driven by a control cylinder 35. The pushing member 30, in the shape of an elongated stem, is connected to a shank 36 protruding from the longitudinal slot in the guide tubular member; the shank 36 is connected to an endless chain 37 operatively connected to a driving motor 38 (Fig. 4). Therefore the assembly of the tubular guide member 29, the pushing member 30, the chain 37 and the driving motor 38 is supported in a rotary manner between a lowered position, shown in an unbroken line in Fig. 4, in which the movement of the carriages 12 does not interfere with the supplementary guide, and a raised position, indicated by a dotted line in Fig. 4, in which the supplementary guide member 29, with the relative pushing member 30, are axially aligned to the bar 13 supported in a rotating and sliding menner by the carriages 12 of the feeder. If required, the shank 36 of the pushing member can be guided in its travel by a hollow guide 39 fixed to the rotational axis 32, which also serves for the passage of the return branch of the endless chain 37. Fig. 6 of the enclosed drawings shows a variation of the supplementary movable guide according to this invention. In the case described previously, the guide was in the form of a tubular member and comprised of a pushing stem having a greater length than the tubular guide, so as to enable the bar 13 to be fed for the whole length of the machine tool mandrel to which the feeder is connected. Unlike the previous case, the guide member in Fig. 6 is now in the form of a semicircular cradle 40, fixed on one side to rotary arms 31. The semicircular cradle 40 serves as a guide both for the first pushing member 30, which in this case is shorter in length than the previous one, and for a bar length 13a or another extended element which has to be fed, to move it forward through the guide carriages 12 into the position shown in Fig. 1, towards and inside the mandrel of the machine tool. The pushing member 30 is again connected by means of a side arm 36 and chain drive 37 in the manner explained previously. Laterally to the cradle guide 40, the device comprises a second pushing member 41 sliding in a second tubular guide 42 carried by the arms 21. In this case too the second pushing member 41 has a greater length than the tubular guide 42 and the pushing member 30 in order to intervene subsequently where the latter has left the bar 13a. The pushing member 41 is connected by a shank 43 to a chain drive 44; the two chain drives 37 and 44 engage with the respective toothed wheels 45 and 46 idly supported by a splined shaft 47 connected to a driving motor 48. The two toothed wheels 45 and 46 can be selectively connected to the splined shaft 47 by means of a double pinion 49 sliding along the shaft 47 and driven by a control cylinder 50; the pinion 49 has on its two sides a set of dowels which engage in corresponding lateral holes of the two toothed wheels. In this way, having in the same space two pushing members for the bars, it is possible to obtain forward travels of the bars having a length equal to and greater that of the feeder structure. In this case too, the supplementary guide assembly can be moved between at least two operating positions as shown in Fig. 6, and more precisely between a first operating position in which the cradle-shaped guide 40 and the first pushing member 30 are axially aligned with the carriages 12 of the feeder, and a lateral position, shown by a dotted line in Fig. 5, in which the second pushing member 41 is in this case aligned with the bar 13a so that it intervenes sequently to the previous one. It is clear that, with suitable driving means, the movable guide assembly can be made to rotate both in the operating positions described previously and in a resting position with the guide assembly completely lowered to enable the carriages 12 of the feeder to slide. 51 in Figure 6 indicates an automatic loader for feeding bars 13a to bar feeder 10, the loader is in the form of spaced apart rocking levers 51 driven by a fluid actuated cylinder 52; each lever 51 extends towards the guide 40 and, at its end, far from the cradle or duct shaped guide 40, has a transverse L-shaped head 53 having a pointed or tip-shaped upper protrusion 54 to take, one by one the bars 13a carried by an inclined plane or supporting members 55. Figures 7 and 8 of the drawings show a further embodiment of a device for feeding bars according to the invention, particularly suitable for feeding heavy or large rods. In this case the carriages 12 have four guiding sleeves 19 sliding along four tubular guide rods 11, parallely arranged at the apices of a square. The use of four guide rods 11 enables bars 13 of greater dimensions to be supported and fed, nevertheless the presence of four guide rods means that in this case a guide and pushing device cannot be adopted; in fact the lower rods would prevent the device from rotating inwards. Therefore this manner of construction envisages a tubular guide device 60 carried parallel to the carriage guides 12, by horizontal racks 61; each rack 61 is supported by a pair of lower wheels 62 and a pair of upper toothed wheels 63 which engage with the teeth of said rack 61. One of the racks is connected to a control cylinder 64 and, correspondingly, one of the toothed wheels 63b is connected to the toothed wheels 63b of the other racks by means of a shaft 65. The racks also support two tubular members 66 and 67 in which run the two branches of the chain 68 driven by the motor 69 by means of the driving wheels 70 and 71; the chain 68 is connected at its ends to a cylindrical element 72 which slides inside the tubular member 66 for the entire stroke of the pushing rod 73, for the bars to be fed to the machine tool. The pushing rod 73 running in the tubular member 60, is fixed, for example screwed, to a cylindrical element 74 movable along the tubular member 60. The two tubular members 60 and 66, on facing sides, have a longitudinal slot for the running of an arm or of an intermediate plate 75 connecting the sliding elements 72 and 74. In this way, by driving the chain 68 by means of the motor 69, it is possible to move the pushing rod 73 backwards and forwards along its tubular guide 70; at the same time the assembly of tubular members, carried by the racks 71, can be moved horizontally between a forward position in which the pushing member 73 is axially aligned with a bar to be fed in the carriages 12, as represented schematically by dotted lines in Fig. 7, in which it is inserted between the guides 11 of the carriages, and a retracted position outside said guides.

Claims: A bar feeder for machine tools comprising: a support structure (10) having a longitudinal axis, guide rods (11) parallelly arranged to said longitudinal axis supporting at least a first and a second carriage (12) rotatably supporting a bar (13) bar pushing means to fed said bar (13) towards a mandrel of the machine and drive means (26, 27) for at least one of said carriages (12), characterised in that said guide rods (11) are rigidly connected to said structure (10) at their ends only, to allow oscillating movements for the entere length of said guide rods (11) under the centrifugal forces generated by the rotation of the bar (13), and sleeve guide members (19) for said carriages (12) longitudinally sliding on said guide rods (11), said sleeve members (19) being parallelly arranged and secured to the carriages (12) to maintain said guide rods (11) parallelly spaced apart during oscillating movements of said guide rods (11) conjunctly to said carriages (12). A bar feeder as in claim 1, characterised in that said drive means (26, 27) for said carriages (12) comprises independent drive means for said carriages (12). A bar feeder as in claim 1, characterised in that each carriage comprises an idly rotating bush member (20) for supporting and guiding the bars (13), said rotating bush member (20) being supported inside the carriage body (11) by vibration damping pad means. A bar feeder as in claim 1, further characterised in that it comprises a supplementary bar guide device (26; 30, 42; 60) having at least one bar pushing member (30; 42; 73) and means (32; 61) to movably support said supplementary guide device between an advanced position axially aligned with the bar (13) and a retracted position lateral to the previous one respectively. A bar feeder as in claim 4, characterised in that said supplementary guide device exends for the whole stroke of the bar pushing member (30). A bar feeder as in claim 4, characterised in that said guide device is in the form of a tubular element (29) having a longitudinal slot, and by the fact that the bar pushing member (30) is slidingly positioned inside the tubular guide element (29) and is connected, by a shank projecting from said slot, to a driving means movable with the same guide device. A bar feeder as in claim 6, characterised in that said supplementary guide device, said bar pushing member and said driving means, are rotatably supported around an axis (32) parallelly arranged to the carriage guide rods (11) and by the fact that driving means (33, 35) are provided for rotating the assembly of the guide device and bar pushing member (18, 30), between a raised and a lowered position. A bar feeder as in claim 4, characterised in that said supplementary guide device is composed of a part in the form of an upwardly oriented channel shaped cradle (36). A bar feeder as in claim 8, characterised by comprising loader means (51) for guiding and loading bars towards said cradle (36). A bar feeder as in claim 8, further characterised by comprising a second bar pushing member (41) laterally arranged and movably supported with said cradle (36). A bar feeder as in claim 10, characterised by comprising driving means (47 - 49) selectively connectable to the aforementioned bar pushing members (30, 41). A bar feeder as in claim 1, characterised in that at one end thereof the support structure (10) for the carriage guides (11) comprises a rotating bush member (15) for guiding a bar (13) to be moved forwards towards the machine tool. A bar feeder as in claim 12, characterised in that said bush member (15) is supported by vibration damping means (17). A bar feeder as in claim 4, characterised in that the supplementary guide device and the bar pushing member (73) are movable between an advanced position axially aligned with the carriages (12) and respectively a retracted position external to the carriage guide rod (11). A bar feeder as in claim 14, characterised in that said bar pushing member sliding in the supplementary guide device is operatively connected to drive means (69), said bar pushing member (73) and said drive means (69) being carried by rack members (61) positioned on a side of the slide guides (11) for the carriages (12), and by the fact that drive means (64) are operatively connected to the rack members (61) for moving them forwards and backwards.

Inventors: CUCCHI GIOVANNI, CUCCHI, GIOVANNI
Applicants: CUCCHI GIOVANNI & C SRL, CUCCHI GIOVANNI & C. S.R.L.
Application year: 1989
Main classification: B23B13
IPC codes: B23B13, B23Q7