BACKGROUND OF THE INVENTION

The present invention relates to a guide device for an apparatus for automatic load ing of bars for a machine tool, like a lathe that can be of the single-spindle or multiple spindle type.

PRIOR ART

Different apparatuses are known for guiding and feeding bars to the spindles of a lathe. In general, a bar-feeding apparatus comprises a drum that is rotatable around a hori zontal longitudinal axis thereof and supports a plurality of guides suitable for containing and guiding respective bars to be fed to the aforesaid lathe. The guides are distributed both longitudinally along the drum and circumferentially on the latter.

Current systems for advancing and loading bars for machining on machine tools are generally configured with structures that are very complex both from the structural and functional point of view with connected drawbacks and limits like unsatisfactory levels of reliability and high management and maintenance costs.

More precisely, in relation to the bar guide systems, it should be pointed out that the corresponding structural complexity and the considerable overall dimensions, do not facilitate but on the contrary slow the operations of loading the bars. All this has a negative impact on the levels of productivity of the apparatuses.

It should be further noted that current guide systems do not prove to be sufficiently versatile to adapt each time to specific production needs. To give an example, known guide systems are not able to adapt to bars with sections of different dimensions.

One known example of a guide device comprises pairs of semicylindrical elements that are mutually hinged and connected to a drum. In each pair, one of the two semicylin drical elements is in a stationary position with respect to the drum, whereas the other semi cylindrical element is movable with respect to the drum. In an open position, the semicy lindrical elements are not in mutual contact, are thus spaced apart from one another, so as to permit loading of the bar. In a closed position, the two semicylindrical elements are near one another and in mutual contact to convey and guide the bar to the machine tool.

The aforesaid system is hardly versatile in adapting to different dimensions of the bars to be guided. With a guide device that is so shaped, it is in fact not possible to convey bars having a diameter that is greater than the diameter of the zone bounded inside by the two semicylindrical elements. Further, problems can arise with loading slim bars, i.e. having a diameter less than the diameter of the guides. In fact, problems can arise in using a guide system having a di ameter that is greater than the diameter of the bar to be loaded, because the great extra space available inside the guide, i.e. the resulting gap between the bar and guide surfaces causes unsuitable positioning with the risk of causing jamming of the bar, in particular at the final section facing the lathe.

Incorrect use of the aforesaid guide system can lead to malfunctions for the loading system. Thus, in the case of a variable diameter of the bars to be loaded, it is necessary to replace or modify the guide system so as to adapt the diameter of the bars to be loaded, for example by inserting spacers and/or suitable reduction gears inside the conveying zone, to reduce the free space and adapt the guide device to bars having a smaller diameter.

This entails a significant expenditure of time by the user with clear drawbacks from a financial point of view caused by different factors, from the need to have guides having different sections to the costs and maintenance and replacement of the guides.

Basically, known feeding apparatuses have various limits summarized below. One first limit is in general set by the great complexity both from the structural and functional point of view of the bar loading and guide mechanisms. This often involves unsatisfactory operating times from the point of view of envisaged productivity.

A second limit is that of the possible occurrence of drawbacks using the guide units, that do not always ensure correct advancement of the bars, especially in the case of bars with a very reduced diameter with respect to the inner section of the guide units.

A third limit, which is a consequence of the structural complexity of known appa ratuses, is represented by the inevitable occurrence of greater reliability problems, with re sulting costly maintenance interventions. The structural complexity caused by current load ing and guide systems entails rather high production costs and complicates operations of possible maintenance or replacement of parts, also inevitably causing lengthy machine downtime, with resulting financial losses for the user.

Other guide devices for bars are known from EP3456444 and EP0384344.

In the light of the above, there is ample room for improvement of current bar feeding apparatuses.

OBJECTS OF THE INVENTION

One object of the present invention is to improve and simplify structurally and functionally apparatuses for guiding, feeding and advancing bars to machine tools. Another object of the present invention is to provide a versatile guide device that is able to adapt to different production needs, for example to bars having a small diameter.

Another object is to provide a guide device for advancing and feeding bars provid ed with a higher operating speed, which is able to lower drastically bar-feeding cycle times.

A further object is to provide a guide device for advancing and feeding bars that, having a more simplified structural and functional configuration than known apparatuses, results in lower manufacturing and maintenance costs and shorter downtime for mainte nance.

A further object of the present invention is to provide a guide device that is easy to mount on any existing bar-feeding apparatus, with clear advantages in terms of cost and assembly time.

SHORT DESCRIPTION OF THE INVENTION

The above can be achieved by the solution as defined in the attached claims.

In particular, the apparatus according to the invention is structurally configured in a manner that is advantageously simplified with respect to prior art apparatuses, and this re sults in an increase in mechanical reliability and also a reduction in manufacturing and maintenance costs.

The particular configuration of the apparatus, owing to the guide and containment action performed by the second holding and guide means, enables possible flexure to be minimized of bars being advanced and rotated and is able to adapt to bars having a diame ter comprised in a wide range, in particular to slim bars, i.e. having very reduced cross sec tions.

Owing to the solution according to the invention, all the objects set out above are achieved.

SHORT DESCRIPTION OF THE DRAWINGS

These and further features, according to the present invention, will be clearer from the following description with reference to the attached drawings, in which:

Figure 1 shows the guide device for bars to be fed to a machine tool according to the invention;

Figure 2 shows a detail of the guide device in Figure 1;

Figure 3 is a side view of the guide device;

Figure 4 is a side view of the guide device in an operating mode; Figure 5 is a cross section of the guide device;

Figure 6 is a cross section of the guide device shown in Figure 4;

Figure 7 is a side view of part of a bar-feeding apparatus that supports the guide de vice according to the invention;

Figure 8 shows schematically the operation of an advancement device included in the feeding apparatus;

Figures 9 and 10 show, in a section view, two embodiments of the guide device ac cording to the invention, with which an advancement device of the belt or conveyor type is coupled according to two different possible configurations;

Figure 11 shows, in section, a further embodiment of the guide device coupled with a different type of advancement device;

Figure 12 shows another embodiment of an advancement device included in the feeding apparatus in a rest position;

Figure 13 shows the advancement device of Figure 10 in an operating position. DETAILED DESCRIPTION OF THE INVENTION

With reference to the attached Figures, a guide device 1 is shown for guiding and conveying automatically bars B to a machine tool such as for example a lathe, which can be of the single spindle or multispindle type.

The guide device 1 comprises first holding and guide means 2,5 and second holding and guide means 4,7, arranged so as to define an advancement zone 3 for the bars B to be fed to the lathe.

The advancement zone 3 extends along a longitudinal axis X that can, for example, coincide with the longitudinal axis of the cylindrical bars B to be conveyed to the machine tool.

The first holding and guide means 2,5 and the second holding and guide means 4, 7 are configured to establish one or more contact zones with the bar B, so as to hold in posi tion and slide longitudinally the bar B along the advancement zone 3 that is defined by the first holding and guide means 2,5 and the second holding and guide means 4,7.

The first holding and guide means 2,5 and the second holding and guide means 4,7 extend parallel to the axis X and are positioned on sides mutually opposite the longitudinal axis X.

The aforesaid first holding and guide means 2, 5 and second holding and guide means 4, 7 are relatively movable between a rest position R and an engagement position L. When arranged in the rest position R, the first holding and guide means 2,5 and the second holding and guide means 4,7 are at a greater mutual distance and in positions that are fur ther from the advancement zone 3, in order to enable the bar B to be guided along the ad vancement zone 3 to be positioned therebetween.

When arranged in the engagement position L, the first holding and guide means 2,5 and the second holding and guide means 4,7 are at a lesser mutual distance and nearer than the advancement zone 3, so as to come into contact and maintain the bar B in the correct position along an advancement direction A.

More precisely, on the first holding and guide means 2,5 and on the second holding and guide means 4,7, housing seats 6 are obtained that are suitable for receiving and guid ing the bars B. Each housing seat 6 has, according to a transverse plane, a curved concave profile.

In the embodiment shown in the attached figures, the housing seats 6 of the first holding and guide means 2,5 and of the second holding and guide means 4,7 have, accord ing to a transverse plane, a profile of semicircular shape that is such as to bound, when the first holding and guide means 2,5 and the second holding and guide means 4,7 are coupled with one another, a cylindrical advancement zone 3 having a diameter D.

In this direction, the first 2,5 and the second 4,7 holding means are configured to adapt to different diameter values of the bar B. In particular, the guide device 1 that is so configured can guide bars B having a diameter that is the same as or less than the reference diameter D.

The housing seat 6 is coated with or obtained integrally with a material having anti friction properties, in order to avoid obstacles to and slowing of the sliding of the bar B in side the advancement zone 3. For example, the housing seat 6 can be coated with or ob tained integrally with a piece of material having anti-friction properties chosen from a group comprising: polytetrafluoroethylene (PTFE), a polyamide containing graphite, a metal or metal alloy coated with graphite or a ceramic material.

The guide device 1 further comprises a driving member 8 connected to an end of the first holding and guide means 2,5 and/or of the second holding and guide means 4,7 to move the first holding and guide means 2,5 and the second holding and guide means 4,7 between the rest position R and the engagement position F. The driving member 8 com prises a hydraulic or pneumatic actuator.

In one embodiment of the invention, shown in the attached figures, the first holding and guide means 2,5 comprises a first series 2 of distinct guide elements 5 having a block shape. The guide elements 5 are mutually spaced apart and distributed parallel to the axis X.

The second holding and guide means 4,7 comprises a second series 4 of distinct block- shaped guide-elements 7. The guide elements 7 are mutually spaced apart and dis tributed parallel to said axis X, in a position opposite the guide elements 5 of the first series

2.

More precisely, the guide elements 5 of the first series 2 are arranged staggered with respect to the guide elements 7 of the second series 4, so as to entirely involve the ad vancement zone 3 and, consequently, the bar B to be guided inserted into the aforesaid zone. The guide elements 5 of the first series 2 are connected mechanically to the guide el ements 7 of the second series 4 by connecting means 9, so as to form an articulated guide structure 17.

Owing to the reciprocal mechanical connection between the guide elements 5 and 7, the first series 2 of guide elements 5 and the second series 4 of guide elements 7 are movable in a simultaneous and synchronised manner between the rest position R and the engagement position L

The connecting means 9 comprises connecting rod elements 9, the ends of which are connected respectively to a guide element 5 of the first series 2 and to a guide element 4 of the second series 7.

The connecting rod elements 9 are configured to rotate around respective pivots 10. The pivots 10 are provided in an intermediate zone of the respective connecting rod ele ments 9 and in a middle zone interposed between the first series 2 of guide elements 5 and the second series 4 of guide elements 7. In this manner, the rotation of the connecting rod elements 9 results in a displacement that is equal but in opposite directions of the first se ries 2 of the guide elements 5 and of the second series 4 of the guide elements 7.

The connecting rod elements 9 define an articulated parallelogram connection be tween the first series 2 of guide elements 5 and the second series 4 of guide elements 7. In order to create the articulated parallelogram connection, each of the second ends 12 of the guide elements 5 is connected by a respective connecting rod element 9 to the respective first end 13 of the guide elements 7 and each of the second ends 14 of the guide elements 7 is connected by a respective connecting rod element 9 to the respective first end 11 of the guide elements 5. According to this arrangement, the guide elements 5 of the first series 2 and the guide elements 7 of the second series 4, starting from the rest position R, approach simul taneously the advancement zone 3, remaining in a position that is parallel to the axis X, un til it adopts the engagement position L, coming into contact with the bar B.

The connecting rod elements 9 are pivoted on an oblong connecting plate 15, con figured to be able to be mounted on support drum units 16 of a bar-feeding apparatus.

The oblong connecting plate 15 is fixed to the support drum unit 16 by screw means and/or by pin means provided at the pivots 10, so as to engage the screw means with corresponding holes made on the support drum unit 16. Other means of fixing the oblong connecting plate 15 to the support drum unit 16 can nevertheless be envisaged.

As mentioned above, the guide device 1 is configured to be mounted on apparatus es 18 for feeding bars B to a machine tool. The apparatus 18 comprises the aforesaid drum unit 16 supporting a plurality of guide devices 1, as disclosed previously, for simultaneous loading of a plurality of bars B. The guide devices 1 are circumferentially distributed around the support drum units 16. The apparatus 18 further comprises an advancement unit 20, 30, 40 for advancing the bars B to a machine tool.

Some embodiments of the advancement unit 20, 30, 40 are illustrated below.

In some first embodiments, with reference to Figures 8 to 10, the advancement unit 20 comprises dragging chain or belt means 22 to which a dragging pusher 21 and/or bush ing gripper is connected that is configured to come into contact with the bar B.

The chain means 22 is movable to translate the dragging pusher 21 and/or the bush ing gripper, so as to advance a respective bar B along the advancement direction A. The chain means 22 is drivable by an electric motor of brushless type.

In particular, the pusher 21 comes into contact with the rear end of the bar B, exert ing on the latter a thrust action that advances the bar B along the advancement direction A. In other words, the pusher 21 is configured to push from the rear the bar B, whilst the dragging bushing gripper, in which the bar B is inserted, is configured to move altemating- ly, by a “pilgrim step”: during the retraction step, it slides without gripping the surface of the bar whilst advancing forwards it grips, with friction, the bar, causing the bar to move to the lathe. In another possible embodiment, combined or alternating with what has just been disclosed, with the chain means 22 a gripper can be coupled with grasping claw elements that are able to close or open to clamp and release the bar - alternatingly and synchronized with the pilgrim step movement thereof - so as to advance the bar by steps to the lathe. The chain or belt means 22 can alternatively comprise one, two or more chains, ar ranged according to different possible configurations. In the embodiment shown in Figure 9, the chain 22A traverses the second 7 holding and guide means. In the embodiment of Figure 10, the chain 22B traverses the first holding and guide means 5 holding and guide means. In another embodiment (that is not shown) it is possible to combine these two con figurations that have just been shown.

The advancement unit 20 comprises containment and protection channel means 24,25 inside which the dragging chain or belt means 22 is movable. The containment and protection channel means 24,25 comprises profile elements 24 that bound containing cavi ties and hollow profiled elements 25.

The profiled elements 24 with the containing cavities extend passing through inner zones of the first holding and guide means 5 and/or second holding and guide means 7. The profiled elements 24 have a section that is open - towards the advancement zone 3 - such that from the respective open containing cavities connecting portions can protrude that connect the pusher 21 and/or the gripper to the respective branch of the chain, which is placed and movable inside the containing cavity.

The hollow profiled elements 25 are interposed between the first holding and guide means 5 and/or second holding and guide means 7 and the mechanical connecting elements 9. For example, the hollow profiled elements 25 can have a cross section (according to a plane that is transverse with respect to the axis X) with a closed polygonal profile, for ex ample can be shaped according to the profile elements with a closed square or rectangular section. The cross sections of the channel elements 24,25 are sized so as to leave ample space to the respective chains 22 contained therein so as not to hinder the movement of the latter and not to hinder the movement of the first holding and guide means 5 and/or second holding and guide means 7.

The chain or belt means 22 moves along a closed circuit that extends inside the containing cavities of the channel means 24 and 25 that has just been disclosed. Inside the aforesaid containing cavities, the chain means 22 moves so as to translate the dragging pusher 21 and/or the bushing gripper along the advancement direction A, so as to enable the dragging pusher 21 and/or the bushing gripper to perform the function of pushing and pulling and accompanying on the bar B. In this manner, the bar B is advanced to the ma chine tool. The movement of the chain or belt means 22, induced by the brushless electric motor, is reversed to enable the pusher 21 to be repositioned - once complete advancement of the bar B has terminated - upstream of the rear end of a new bar B to be fed, or to re tract by an appropriate amount the dragging bushing gripper that must engage with the new bar B to be fed. During the advancement movement, the bar B is maintained in the correct position by the guide elements 5,7.

Figures 9-10 show schematically and by way of example the various possible con figurations of the advancement unit provided with the belt or chain means 22. The radial plane P has been indicated (in Figure 9), which is defined by the axis X and by an axis Y of the drum, visible for example in Figure 5.

As visible in Figure 9, in one embodiment, a chain element 22A is provided (to which a pusher or a bush gripper is connected) that extends on a plane parallel to the afore said radial plane P, traversing the first holding and guide means 5. In another embodiment, visible in Figure 10, a chain element 22B is provided (to which a pusher or a bush gripper is connected) that extends on a respective plane parallel to the aforesaid radial plane P, traversing the second holding and guide means 7.

In another embodiment, it is possible to provide both the chain element 22A and the chain element 22B.

According to a still further embodiment, the advancement unit 40 comprises a slid ing rail track 43 mounted on the drum unit 16. On the rail track 43, a slide element 41 is movable, to which a pusher element 21 and/or a dragging bushing gripper is connected to advance a respective bar B along the advancement direction A. Similarly to what has been disclosed with reference to the system of advancement with belt means, also in the case of a rail track 43 and slide element 41 or cursor, it is possible to provide, mounted on the lat ter, one or more grippers with grasping claw elements that are able to close and open to grasp and release - in a manner alternating and synchronized with the pilgrim step move ment - the bar that is thus advanced by steps.

In a first embodiment, the rail track 43 comprises a magnetic or electromagnetic rail and the slide element 41 is an electromagnetic or magnetic unit. The magnetic or elec tromagnetic interaction with the rail 43 by the slide element 41 determines the sliding movement of the latter along the advancement direction A and in the opposite direction.

The slide element 41 advances along the magnetic rail 43, translating the dragging pusher 21 and/or bushing gripper and accompanying the bar B along the advancement zone 3. After guiding the bar B to the machine tool, the slide element 41 travels back in the op posite direction to the advancement path so as to permit advancement of a further bar B. In a second embodiment, the rail track 43 and the slide element 41 are coupled with one another according to a screw-nut screw system. The slide element 41, coupled by a thread with a respective thread of the rail track 43, is moved, in the advancement direction A or in the opposite direction thereto, owing to the rotation of the rail track 43 induced by a motor, for example an electric motor of brushless type. The action of pushing and ac companying the bar B is identical to what was disclosed for the aforesaid case of the mag netic rail.

According to a further embodiment, shown in Figures 12 and 13, the advancement unit 30 comprises a support and guide member 31 of the belt type or the conveyor type, configured to supportingly receive, on a first side LI, a bar B and to guide the bar B along the advancement direction A. The advancement unit 30 further comprises a grasping mem ber 32 of the belt type or the conveyor type along a direction T transversely to said ad vancement direction A from a disengagement position PI to a locking position PI.

The support and guide member 31 and the grasping member 32 comprise a belt or a conveyor element 33 which is wound around a pair of wheel elements 34, that are spaced apart and rotatable around respective axes W, arranged transversely to the advancement di rection A.

The belt or a conveyor element 33 is shaped to come into contact with the side sur face of the bar B, to exert thereon the dragging action along to advancement direction A.

In the disengagement position PI, the grasping member 32 is furthest from the sup port and guide member 31, so as to result being separated from the bar B. In the locking position P2, the grasping member 32 is nearer to the support member 31 and presses longi tudinally the bar B from a second side L2 opposite the first side LI and against the support member 31.

Advancement motor-means M is provided that is configured to rotate the support and guide member 31 and/or the grasping member 32 in the locked P2 position and to drag and advance the bar B along the advancement direction A.

The motor means M comprises an electric motor of brushless type.

A displacement member Z is further provided to translate the grasping member 32 from the disengagement position PI to the locked position P2.

As is apparent from the above, the guide device 1 successfully achieves the set ob jects. The device 1 proves itself to be a simplified mechanism for guiding bars to be fed to a machine tool. The device 1 is suitable for guiding bars with a wide range of diameters. In fact, the first holding and guide means 2,5 and second holding and guide means 4,7 are configured to adapt, during the operation of coupling and contact with the bar B to be guided, to the diameter of the bar B. The guide elements 5,7 approach and come into contact with the bar to be guided as far as possible, in function of the diameter of the latter, so as to ensure cor rect advancement of the bar to the machine tool.

The guide device 1 has a structural and functional configuration that is greatly sim plified with respect to known apparatuses.

The simplicity with which the constructional elements of the guide device 1 are connected together implies a lower occurrence of faults or breakdowns and lower produc tion and maintenance costs.

The operation of the guide device 1 is fast, efficient and reliable. Also owing to the structural simplicity of the machine, using the device 1 ensures high levels of productivity.

Any component that is part of the guide device 1 according to the invention can be replaced by other equivalents in structural and functional terms and the materials, inas much as they are compatible with the specific use for which they are intended, can be cho sen appropriately in function of the requested requirements and in function of the available prior art.

Variations on and/or additions to what has been disclosed above and illustrated in the attached drawings are possible without thereby falling outside the claimed protective scope.