TOOL

DESCRIPTION

The present invention relates to an apparatus for advancing and supplying bars to a machine tool, in particular to an automatic lathe.

Apparatuses are known for automatically supplying bars to the spindle of a lathe, which are provided with a support drum that extends longitudinally and supports a plurality of openable guides for the bars. The support drum is configured for rotating around the longitudinal axis thereof.

The openable guides are distributed both longitudinally along the drum and circum- ferally on the latter.

Each openable guide comprises a fixed part, i.e. mounted in a stationary part on the drum, and a part is transversely movable to the longitudinal axis of the drum.

The movable part, which is movable by suitable mechanism, is first moved away and then moved near the respective fixed part so as to enable a bar to be inserted that has to be guided during processing.

A plurality of bar-pushing members is further provided that are supported movably axially on a rear portion of the aforesaid elongated drum, each bar-pushing member being arranged for pushing to the lathe, a respective bar along a respect group of aforesaid openable guides aligned longitudinally.

The bar-pushing members then intervene at the rear, i.e. exert a thrust on the rear end of the bar, i.e. the end of the bar that is further from the spindle of the machine tool to which it has to be supplied.

Once supplying of a bar has been completed it is thus necessary to return the bar- pushing member totally to the rear end of the apparatus, travelling the entire longitu dinal dimension of the support drum, so as not to interfere with or hinder the task of loading a successive bar.

In order to be able to insert a new bar, it is thus necessary for the bar-pushing mem ber to retract substantially over the entire stroke to return to a position further up stream with respect to the supply direction and this slows significantly the operating time of the apparatus.

Another drawback of this apparatus, in addition to unsatisfactory operating times, is that it is structurally rather complex and thus involves rather high manufacturing costs. Further, the configuration that provides for the bar-pushing member acting to the rear on the bar unfortunately inevitably entails an increase in the longitudinal overall dimension, because of the operating spaces required of necessity by the bar pushing member.

A further limit of the aforesaid apparatus is linked to the operation of evacuating the residual portion at the end of the supplying cycle. As the bar is pushed at the rear and thus has the possibility of moving in only one direction, i.e. only approaching to the machine tool, the residual portion has necessarily to be expelled and dropped outside beyond the front end of the drum, i.e. in a zone interposed between the supplying ap paratus and the spindle of the machine tool. Obviously, the risk is not excluded that the residual portion can in this zone damage the spindle or may adversely interfere with the machining tasks performed by the machine tool.

The structural complexity of the apparatus that has just been disclosed inevitably en tails greater problems of reliability with resulting costly maintenance tasks.

The structural complexity caused by the openable guides complicates possible maintenance or parts replacement operations, thus inevitably causing long machine downtime, with resulting financial loss for the user.

One object of the present invention is to improve and simplify structurally and func- tionally the apparatuses for supplying and advancing machine tool bars.

Another object is to provide an apparatus for advancing and supplying bars that is provided with a higher operating speed that is able to slash drastically the bar supply ing cycle time.

A further object is to provide an apparatus for advancing and supplying bars that, having a structural configuration that is more simplified than that of known apparat uses, entails lower manufacturing costs and shorter maintenance time.

The above can be achieved by an apparatus for advancing and supplying bars to a machine tool as defined in claim 1.

Owing to the invention the aforesaid drawbacks are overcome.

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

The particular configuration of the apparatus, owing to the action of guiding and con taining the tubular elements, enables possible flexures of the rotating bars to be min imized, especially in the case of thin bars, i.e. bars having very reduced cross sec tions; in addition, owing to the feed finger units, loading and supplying of the bars is significantly simplified and accelerated, further enabling the residual portions of the bars to be expelled, inside the volume bounded by the apparatus, thus far from the spindle of the machine tool, which is thus protected from possible risks of damage.

Further features and advantages will be clear from the appended claims and the de scription.

The invention can be better understood and implemented with reference to the at tached drawings, which illustrate an embodiment thereof by way of non-limiting ex- ample, in which:

Figure 1 is a perspective view of the apparatus according to the invention, fitted to a frame from which, for greater clarity, some parts have been removed, such as a housing and protection casing;

Figure 2 is a perspective view of the apparatus according to the invention;

Figure 3 is a cross section of the apparatus according to the invention;

Figure 4 is a fragmentary view in which a driving device for driving the appa ratus is visible;

Figure 4bis shows another embodiment of the driving device of figure 4;

Figure 5 is an enlarged view of a part of the apparatus shown in figure 2;

Figure 5bis shows, in section, a feed finger unit;

Figures 6 and 7 are two different views of a drum structure to which two carriag es of the apparatus are slidably fitted;

Figure 8 is a longitudinal section taken along the plane VIII- VIII in Figure 7 ; Figures 9 and 10 are two different views of a carriage of the apparatus;

Figure 11 is a section of the carriage taken along the plane XI-XI in Figure 10; Figures 12 to 23 show a sequence of operating steps of the apparatus.

With reference to the attached Figures, an apparatus 1 is shown for supplying, auto matically, bars 2 to a machine tool, in particular to a lathe that can be of the single spindle or multi-spindle type. By way of example, the lathe of single- spindle type is configured to perform a single machining task on one bar at a time, whereas the lath of multi-spindle type enables several bars to be machined simultaneously, or enables a bar to be subjected to subsequent machining tasks of different type, i.e. it has sever al machining stations that can have the same tools, or also tools that are different from one another.

The apparatus 1 is provided with a support frame 40 with panels (not shown) to cover and protect the inner components.

The apparatus 1 has an end that is suitable for being placed in a position adjacent to a spindle of the lathe, and a longitudinal axis of which extends, that, during operation, is aligned on or anyway parallel to the rotation axis of the spindle to be supplied. The apparatus 1 is provided with several tubular elements 3 each suitable for contain ing longitudinally a respective bar 2 to be supplied and comprises at least one first carriage unit 4, or front carriage unit 4, and a second carriage unit 5, or rear carriage unit 5, arranged for supporting these tubular elements 3.

Both the first carriage unit 4 and the second carriage unit 5 each consist of a plurality of carriage elements 15, that are integral with one another or decoupled from and in dependent of one another, as disclosed better below.

Each tubular element 3, more precisely, is a hollow cylindrical bar. Thus, advanta geously, the tubular elements 3, which act as continuous containing cylinders, have a very simplified structural configuration.

The first carriage unit 4 and the second carriage unit 5 are movable longitudinally on a drum structure 6 to move the tubular elements 3 in the advancement direction A of the bars 2.

The drum structure 6 extends from a front end EA, suitable for being placed in a posi tion adjacent to the spindle of the machine tool, to a rear end ER, SO as to be further from the spindle, thus from the machine tool.

Each tubular element 3 is provided with a feed finger unit 7, disclosed better below, that is suitable for clamping and pulling the respective bar 2 so as to make the bar 2 advance in advancement direction A.

Each feed finger unit 7 is fitted in a front end 8 of the respective tubular element 3 to be nearer the spindle of the machine tool.

Each tubular element 3 extends over a length L approximately equal to or greater than half of a total length L _T of the drum structure 6.

Owing to this configuration, the tubular elements 3 are able to contain, internally, isolated from the exterior, the bars 2 for a significant length. This is particularly ap preciable when the bars 2 have greatly reduced cross sections, i.e. they are very thin and for this reason they are subject to undergoing flexure because of the centrifugal action during rotation induced by the spindle.

This is avoided owing to the tubular elements 3 that accompany and support the bar 2 as far as complete introduction into the spindle and for the entire supply time. Amongst other things, the aforesaid configuration also entails a reduction of the nois es associated with the rotation of the bar 2.

Each feed finger unit 7 comprises gripping elements 9 provided with conical cou pling surfaces and with gripping surfaces for clamping and pulling the bar 2.

The gripping surfaces are made of plastic or rubber or metal or another material, and have a high sliding friction coefficient; they are then shaped for generating a grip contact with the surface of the respective bar 2 so as to be able to push the latter in the advancement direction A to the spindle.

The gripping elements 9 are further configured to loosen the clamping action on the surface of the bar 2 and instead permit a relative slide of the feed finger unit 7 along the surface of the respective bar 2 in a direction opposite the supplying direction of the bar 2, when the respective tubular element 3 is moved away from the said ma chine tool.

In other words, when the tubular element 3 is advanced in the advancement direction, thus to the spindle, the gripping elements 9, arranged around the bar 2, receive from the tubular element 3, by the conical coupling, a thrust action that compresses the gripping elements 9 against the interposed bar 2. In this manner firm clamping of the bar 2 is achieved that is thus dragged automatically by the feed finger unit 7 to the spindle.

Vice versa, when the tubular element 3 is retracted and thus moved away from the spindle, we automatically witness loosening of the thrust action on the gripping ele- ments 9, which accordingly undergo slight radial expansion, the clamping action on the bar 2 thus ceasing. In this manner, the tubular element 3, during retraction, does not drag the bar 2 with it.

Owing to the feed finger units 7, a subsequent alternating backward and forward movement of the tubular elements 3 is translated into a series of one-directional ad vancement steps of the bars 2 to the spindle. Positioning each feed finger unit 7 in the front end 8 of the respective tubular element 3 ensures a correct supply of the entire bar 2 to the spindle.

The drum structure 6 comprises, at a front end E _A thereof, a front end flange 10, pro vided with respective openings 11 through which the tubular elements 3 can slidably traverse the front end flange 10 to protrude, beyond the front end E _A , to the spindle of the machine tool.

The tubular elements 3 are axially integral with the second carriage unit 5, and axial ly movable with respect to the first carriage unit 4.

The first carriage unit 4 and the second carriage unit 5 are movable from a configura tion of mutual proximity in which they are packed towards the front end EA SO that the tubular elements 3 protrude by a substantial amount outside towards the machine tool, to a mutually spaced configuration, in which the second carriage unit-5 is fur ther from the front end EA SO as to drag the tubular elements 3 to the rear end E _R and enable the bar 2 to be inserted progressively into the respective tubular element 3.

In the configuration of mutual proximity of the two carriage units 4, 5 - to which completion of the supply stroke of a bar 2 to the spindle corresponds -, the two car riage units 4, 5 are“packed” against the front end flange 10, thus far from a central zone intended to receive a subsequent bar 2 to be loaded into a respective tubular el ement 3. In other words, the two carriage units 4, 5 do not interfere with the bar 2, which- owing to a lever unit 20 disclosed below - is removed from a magazine con nected to the apparatus 1 and is lowered to the correct height to be axially aligned on the tubular element 3 that is intended to receive the bar 2 internally. The front end 8 of each tubular element 3 has a radially widened shape that prevents separating thereof from the first carriage unit 4 (front carriage) and permits dragging of the first carriage unit 4 to the rear end E _R .

At least one tubular element 3 comprises a respective sleeve unit 12, structurally con figured for containing at least one part of the advancing bar 2 and acting as a protec tive screen.

Each sleeve unit 12 is defined by several adjacent parts 12 A, 12B that are longitudi nally mutually slidable so as to define a containing structure of longitudinally ex pandable type, which is movable from a contracted containment configuration CC (visible in Figure 12), to an extended containment configuration EC (visible in Figure 17).

More precisely, the aforesaid parts that compose a sleeve unit 12 comprise first sta tionary sleeve portions 12 A, arranged for shielding the bar part that protrudes outside beyond the front end E _A , and second movable sleeve portions 12B, arranged for screening the bar 2 part comprised between the first carriage 4 and the front end E _A of the drum structure 6.

The first stationary sleeve portions 12A extend, from the front end E _A to the outside of the drum structure 6, to the machine tool. The second movable sleeve portions 12B are connected to the first carriage unit 4 to be dragged to the rear end E _R to move from the contracted containment configuration CC, in which they are gathered to gether and aligned on, i.e. compacted with, the first stationary sleeve portions 12A, to the extended containment configuration EC in which they are spaced apart from the first stationary sleeve portions 12A.

As mentioned before, the first carriage unit 4 and the second carriage unit 5 each consist of a plurality of carriage elements 15, which are arranged circularly around the longitudinal axis of the drum structure 6 and are slidable along the latter. Each carriage element 15 is shaped as a locking element. The carriage elements 15 are each provided with respective openings 16, provided with bearings 17, into which the respective tubular elements 3 are inserted. The bear ings 17 ensure correct rotation of the tubular elements 3 with respect to the openings 16 in the absence of friction and vibrations.

In the embodiment disclosed here by way of non-limiting example in the attached Figures, the first carriage unit 4 has an annular structure consisting of certain number of carriage elements 15, in this case six (but another desired number is not ruled out) shaped as locking elements, which are arranged circularly around the longitudinal ax is of the drum structure 6 and are mutually connected to define a single body.

The carriage elements 15 of the first carriage unit 4 are integrally connected to one another to form an annular structure.

Between one locking element 15 and another coupling elements 26 are interposed, provided with through openings that couple with and are slidable along horizontal guide bars 27 that extend from one end to the other of the drum structure 6.

Also the second carriage unit 5 is formed in a similar manner to what has been dis closed with reference to the first carriage unit 4.

Longitudinal support and guide channels 18 are obtained along the drum structure 6.

The locking elements 15 of the first carriage 4 and of the second carriage 5 are pro vided with wheel elements 19 placed further inside the annular structure and housed inside, and slidable along the respective longitudinal support and guide channels 18.

According to another possible embodiment (which is not shown), the carriage ele ments 15 of the first carriage unit 4 are drivable and slidably moveable independently of one another, owing to respective belt or chain elements; in other words, each car riage element 15 can move independently of the other carriage elements 15 with which they define the respective carriage unit. What has just been said applies simi- larly to the second carriage unit 5. This embodiment enables the apparatus 1 to sup ply, to a multi-spindle machine, a plurality of bars 2 autonomously and independently of one another to subject such bars 2 simultaneously to several machining tasks that can be, if desired, of different type. The great advantages are thus clear that arise from the point of view of the versatility of the apparatus 1.

The apparatus 1 comprises a driving device 13 arranged for moving longitudinally, by suitable chain or belt elements 21, or the equivalent, the first carriage unit 4 and the second carriage unit 5 along the drum structure 6.

The driving device 13 is also configured for being able to rotate the drum structure 6 around the longitudinal axis thereof.

As is visible in Figure 4, the driving device 13 has a transmission with a pinion 23 suitable for engaging directly respective gearwheels 22, each associated with a tubu lar element 3 which can be thus driven. The pinion 23 engages each time a single gearwheel 22, to move the associated tubular element 3.

In one embodiment, shown in Figure 4bis, the driving device 13 comprises a chain element 24 interposed between the pinion 23 and the gearwheels 22. The chain ele ment 24 is wound around, and slides along, a support 25 with an arched guide profile 26 so as to be able to engage simultaneously two adjacent gearwheels 22. In particu lar, the chain element 24 enables the arch or operating angle to be enlarged in which the pinion 23 remains engaged with each gearwheel 22; in other words, engaging the pinion 23 with a gearwheel 22 occurs not only at a single angular position value of the drum structure but extends to a wider angular interval so as to enable for the ex ample the drive of a carriage to be anticipated, moving the drive already before the drum structure 6 has been rotated in the preset angular supply position of a bar.

This configuration thus enables the device 13 to anticipate the drive of the subse quent gearwheel when the drum structure 6 is rotated by an angular pitch to prepare a subsequent tubular element 3 for the supplying step. In other words, by widening the field of intervention of the pinion 23, the drive of the carriage units 4 and 5, and thus of the respective feed finger unit 7, is more versatile and - at least partially - unconstrained by the precise angular position of the drum structure 6.

From this configuration clear advantages of versatility and optimization of the oper ating cycles associated with the apparatus 1 arise.

The apparatus 1 comprises, as already mentioned above, a lever unit 20 to support horizontally and load each bar 2 in a respective tubular element 3. The lever unit 20 is rotatable around a rotation axis R parallel to the longitudinal axis of the drum structure 6 to transfer a respective bar 2 to a loading height where it is axially aligned on a respective tubular element 3. Suitable position sensors are provided to detect continuously the angular position of the lever unit 20 to permit the advancement of the carriages, preventing them from interfering therewith. Owing to these sensors, the movement of the lever unit 20 is coordinated with the movement of the carriage units 4 and 5.

The apparatus 1 is provided with sensors 25 to detect the position of the first carriage unit 4 and/or of the second carriage unit 5.

The apparatus 1 also comprises a control and synchronization unit U, operationally connected to the sensors 25 to detect the position of the first carriage unit 4 and of the second carriage unit 5.

The control and synchronization unit U is programmed for driving in a synchronized manner the drum structure 6, the lever unit 20, and the first carriage unit 4 and the second carriage unit 5 to permit loading of each bar 2 in a respective tubular element 3, and the advancement of the bars 2 to the machine tool.

The control and synchronization unit U is configured and programmed to advance each bar 2 by a succession of reciprocating movements forwards and backwards of the second carriage unit 5 until the bar 2 has been supplied completely to the spindle. Further, the control and synchronization unit U is programmed to transfer and release a residual portion of the machined bar 2, in an internal zone Z of the apparatus 1, placed further upstream of the front end E _A with respect to the machine tool. The re sidual portion is expelled from the respective feed finger unit 7 through the effect of the thrust exerted by a new bar 2 that is loaded and introduced into the respective tubular element 3. Owing to this possibility of releasing the residual portion inside the volume bounded between the two ends of the drum structure 6, any risk is avoid ed in the most absolute manner of interfering with and damaging delicate and costly parts/tools of the spindle zone.

The apparatus 1 can operate according to two possible operating modes. According to a first possible operating mode, the control and synchronization unit U drives, in a synchronized manner, the carriage units 4 and 5, the drum structure 6 and the lever unit 20, to arrange in sequence the bars 2 in the respective tubular elements 3. Once all the tubular elements 3 have been loaded, the plurality of bars 2 can be supplied simultaneously to a multiple spindle.

According to another possible operating mode, a tubular element 3 is loaded with a respective bar 2, which is immediately supplied to the spindle (in this case a single spindle).

The tubular elements 3 can be configured and sized to receive the same diameter of bar 2, or can be configured and sized to receive each a bar of a given diameter.

With reference to Figures 12 to 23, the operation of the apparatus 1 disclosed above is summarized.

Before loading a bar 2, the first carriage unit 4 and second carriage unit 5 are ar ranged in the position nearest the front end E _A of the drum structure 6, come shown in Figure 12, so as not to hinder the operations of movement of the bar 2 by the lever unit 20.

At this point the bar 2, after being removed from the magazine zone, is lowered by the lever unit 20 until it is aligned on the axis of a tubular element 3 intended to re ceive the bar 2.

The rear carriage unit 5 (rear carriage) is moved away from the front end E _{A SO} that the respective tubular element 3 being dragged is placed on the bar 2 to be loaded. In the position shown in Figure 15, the operation of inserting the bar 2 into the tubular element 3 is completed.

It should be noted that a possible residual bar portion in the feed finger unit 7 of this tubular element 3 (which arises from a previous cycle of supplying bars to the spin dle), is automatically expelled to the zone below the drum structure 6 owing to the thrust that the residual bar portion receives from the new bar 2 during the loading step. The new bar, once the preceding residual bar portion has been expelled, remains engaged with the feed finger unit 7.

In this configuration, the bar 2, which will be subsequently rotated, is effectively pro tected by the tubular element 3, which covers a substantial part, whereas another part further downstream is at least partially protected by the sleeve unit 12, which is in an extended configuration EC.

A this point, the two carriage units 4, 5 advance in the supplying direction A with a succession of reciprocating movements forwards and backwards, as the successive figures 19 to 23 show, in such a manner as to advance the bar 2 progressively to the spindle. Owing to the sleeve unit 12, in particular to the stationary parts of sleeve 12 that project to the outside from the front end 10 flange, the bar 2 is screened in the part that is to the outside of the drum structure 6, thus achieving even higher safety levels.

In the position shown in Figure 23, the bar 2 is supplied completely to the spindle, and the carriage units 4 and 5 are already in the correct position to be able to start loading a new bar 2. Thus advantageously, there is no downtime waiting for the next bar to be loaded, unlike prior art systems in which it is on the other hand necessary to retract the bar-pushing members completely before proceeding with loading and the subsequent thrust supplying a new bar.

As can be seen from what has been disclosed above, the apparatus 1:

advantageously ensures high operating speed, drastically slashing bar supply- ing cycle times;

has an extremely simplified structural and functional configuration, in addi tion to overall dimensions that are less than those of the prior art,

has lower manufacturing costs and lower maintenance costs and times. It is possible to configure and size the apparatus 1 in a desired manner according to the applications for which the apparatus 1 can be intended.

Any component that is part of the apparatus 1 according to the invention can be re placed with other equivalents in structural and functional terms, and the materials, inasmuch as they are compatible with the specific use for which they are intended, can be chosen suitably according to the requirements and according to the available prior art.

Variations on and/or additions to what has been disclosed and illustrated in the at- tached drawings are possible, without thereby falling outside the claimed area of pro tection.