EA041188B1 - BLOCK OF SUPPORT AND CAPTURE OF RODS FOR FEEDING TO A MECHANICAL MACHINE - Google Patents

Description

Technical field

The present invention relates to a machine tool bar support and gripping unit and to a bar feeder used by such a unit.

Prior Art

In some types of machine tool, in which the processing is performed directly on the bars of the raw material, the task of feeding the bar (sometimes several meters long) into the machine tool is solved and carried out using special bar feeders that guide and feed the bars in the most suitable way for the machine tool. that accepts them.

In certain types of machine tools, including lathes, such bar feeders are essentially provided:

(i) with a long horizontal guide channel suitable to accommodate the entire length of the rod located along the channel; and (ii) with special pushing means which, in an appropriate mechanically controlled phase and in connection with the opening and closing of the bar gripping devices of the machine tool, cause the bar to move along the channel so that it moves in the direction of the spindle and cause the end part to pass through spindle for specific machining as soon as it reaches the working space of the machine tool.

When machining is completed, the end of the rod, already machined, is cut off and separated from the rest of the rod. The blank from the rod of the remaining length is then moved again through the spindle, and all the operations mentioned above are cyclically repeated until the usable length of the rod is exhausted.

Since such bar feeders are located upstream of the work spindle, and since the entire working head of the machine tool, among other things, is located between these bar feeders and the spindle, the bar, continuously supported on one side by the channel and held by the spindle at its end inserted inside machine tool, has a gap between the bar feeder and the spindle, which is variable in its axial plane without limitation.

As a result, in addition to the spindle transmitting its own high angular velocity to the entire rod during its working rotation, the geometric eccentricity increases, even if the modified gap has a moderate elastic deviation, between the axis of rotation and the center line of the deformed elastic element, which causes bending vibrations. rod. The vibrations generated in this way are distributed to the bar feeder and the machine tool and are also transmitted to the environment as more or less loud noise.

The thinner the rods compared to the length of the gap and/or the greater the eccentricities of the mass of the rod and/or the geometric characteristics of the rod compared to the axis of rotation of the spindle, the more pronounced this disadvantage is.

To counteract this phenomenon, the first measure taken in the prior art is to adapt the shape of the channels of the rod feeder to the actual shape and dimensions of the section of the rod. This is intended to minimize the size aspects by limiting, as much as possible, the residual movement of the rod relative to the channels.

This embodiment includes certain types of bar feeders that are provided with multiple replaceable channels in the same bar feeder design.

However, this solution is not without its drawbacks. The first disadvantage is that this means that production on the machine tool must be interrupted for the time necessary to materially and mechanically replace the channels and pushing means placed in the bar feeder. The negative impact is on the productivity of the machine tool on the one hand, and the increased cost of equipping the bar feeders on the other hand, due to the need to provide a number of different channels to be used, each time according to the specific machining to be performed.

Secondly, this solution does not provide any useful contribution when the rod is not circular, for example, when the rod has defects in roundness, or when it is necessary to machine rods that are polygonal, such as hexagonal, square or rectangular, or with a solid or box section. or without it.

Instead of changing channels, it is not unusual for many manufacturing sites to continuously use the same channel for groups of bars of different shapes.

However, such a measure does not always prove to be a solution, since when there is a noticeable difference in the size of the rods, the channels must inevitably be replaced; and, where it does not, it is often necessary to reduce the spindle speed to limit the frequency of oscillation, which can lead to a clear decrease in production efficiency when falling below the economically viable cutting speed thresholds of a machine tool.

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Another disadvantage of bar feeders in which the bars are continuously supported by a channel relates to the lubrication system that the machine is equipped with, which is necessary to ensure the movement of the bar, in particular when rotating in the channel, under acceptable friction conditions.

Indeed, in this regard, the channels are lubricated by means of a constant circulation of lubricant. Lubrication entering the channel allows the rod to rotate within the channel due to the pulling motion imparted by the spindle under fluid friction conditions, thus avoiding the overheating effects that would otherwise result from frictional heating generated by sliding the surface of the rod over a stationary surface. channel. This constant presence of lubricant lubricating the channel entails at least two additional disadvantages, on the one hand, in the form of an additional increase in the cost of mechanical equipment due to the need to equip the bar feeders with a suitable lubrication system, as well as operating costs associated with a large amount of lubricant , which the installation must be equipped with; and, on the other hand, in the form of the inevitable dispersion of lubricant particles in working environments, which, when sprayed in ambient air, are inhaled by personnel near the installations during work.

Prerequisites for the creation of the invention

The main purpose of the present invention is to overcome these shortcomings by providing a solution for a bar feeder, one and no options, which is able to minimize the conditions that vibrations of bars subjected to machining, and with which this result can be obtained at any perimeter of the transverse section of the bars being machined, and/or even regardless of the shape of their section, which may also not be round.

Another object of the invention is to eliminate the need to lubricate the bars during machining, simplifying the created designs of the bar feeders and making them more economical to create and operate.

According to the invention, such results are achieved by means of a support and gripping unit and by means of a bar feeder, as defined in the appended claims.

Brief description of graphic materials

The technical characteristics and other advantages of the invention will be apparent from the description below with reference to an exemplary embodiment illustrated in the accompanying drawings, in which:

in fig. 1 is a three-dimensional representation of a bar feeder according to the invention;

in fig. 2 is a partial three-dimensional representation of the bar feeder shown in FIG. 1 shown with some parts removed to better show others;

in fig. 3 is a representation of the functional block that is housed in the bar feeder, shown removed from the bar feeder;

in fig. 4 is an axial view of the functional block shown in FIG. 3;

in fig. 5 is a sectional view along the axial plane of the functional block shown in FIG. 3;

in fig. 6 is a sectional view of the functional unit along an axial plane orthogonal to the sectional plane shown in FIG. 5;

in fig. 7 is a sectional view corresponding to that of FIG. 5, with the functional unit shown in a different operating position;

in fig. 8 is a sectional view corresponding to that of FIG. 6 showing the working arrangement of several functional block components;

in fig. 9 is an axial view similar to that shown in FIG. 4 showing another working arrangement of several functional block components;

in fig. 10 is a perspective view of an embodiment of a block according to the invention;

in fig. 11 and 12 are two perspective views of the invention shown in FIG. 10 inserted into a bar loader which also forms part of the invention.

Preferred Mode for Carrying Out the Invention

With reference to the figures in the accompanying drawings in FIG. 1 shows a bar feeder 1 for a machine tool, which is not shown because it is traditional and similar to, for example, a lathe. The machine receiving the bars 3 should be considered to be located on the right in the figure downstream of the bar feeder 1 and aligned with the feed line 4z along which the bar 3 is sent by the bar feeder 1 to the machine tool last for machining.

In FIG. 2 shows that the bar feeder 1 comprises a body 20 extending substantially horizontally, which is supported by a base provided with two vertical uprights 21. A channel 22 is visible inside the body 20, which is suitable for receiving the bar 3, since it extends continuously along it and is intended to guide it in a completely known manner in the horizontal and longitudinal direction relative to itself along the feed line 4z. The rod 3 is moved in continuous motion and in sections along the channel 22 suitably controlled remotely by the machine receiving the rod 3.

If two vertical walls 23 intersect the body 20, only one of which is shown to make the graphics more clear, the bar feeder 1 comprises a bar support and gripping unit 2 3 which is aligned with the feed line 4z and attached to the body 20. In FIG. 3 shows that the support and grip unit 2 comprises two tubular frames 5 having a cylindrical shape running parallel to the feed line 4z, which are provided with an internal through hole 6 coaxial with respect to the direction of the feed line 4z itself. Each of the rods 3 following each other along the channel 22 by passing through the feed line 4z passes through two tubular frames 5 and passes through the inner hole 6 coaxially with respect to the tubular frames 5.

In FIG. 3 shows in particular that the two frames 5 of the support and gripper unit 2 are identical on the outside and are shaped to be horizontally supported by flanges 24, one towards the inside of the bar feeder 1 and the other towards the outside or towards the machine to which the feed is made. .

In FIG. 5 and 6 show that the support and grip unit 2 comprises two rod clamping elements 3, generally designated 7 and 8, which are attached to each of two tubular frames 5, respectively.

Elements 7; 8 for clamping contain, in particular, three pairs of clamps 7a; 8a; 9a, which are switchable between two stroke end positions.

In the first position, the clamps 7a; 8a; 9a are open to their maximum relative distance according to the 4x directions; 4e transverse to the feed line 4z and the rod 3 is free to pass longitudinally with respect to itself through the open clamps 7a; 8a; 9a.

In the second position of the end of the stroke, on the other hand, said clips 7a; 8a; 9a are narrowed and pressed against the outer part of the rod 3.

Frames 5 contain latch blocks 11a; 11b; 11c, which, after a suitable command, are able to grasp the rod 3, which becomes one with them, both in relation to the relative directional movement 4z and, above all, as will be better described below, in relation to the rotation around this direction 4z, which the rod 3 is forced to accept due to rotational movement imparted to it by the spindle of a machine tool when the latter is working during the machining of the rod 3.

In FIG. 4-6 show that compared to FIG. 7 and 8, the two clamps 7a, 7b are preferably located in two different gripping zones 10a, 10b of the rod 3, which are arranged in series with respect to each other and at a certain distance from each other along the direction of the feed line 4z.

In addition, these two clamps 7a; 8a are arranged to switch between their end-of-stroke positions by approaching each other and moving away from each other by moving along two parallel directions, denoted 4x.

The third clamp 7c, despite being substantially located in the zone 10c in close proximity to the grip zone 10b of the second clamp 7b, is positioned to perform its switching by operating along the third direction 4y, which is transverse and perpendicular to the 4x and 4z directions.

In FIG. 5 shows that a fluid linear actuator 14 is located between two tubular frames 5 having a cylindrical body 25 and a tubular shaft 15 uniformly cylindrical, having a through hole 15c, with its longitudinal axis located along the line 4z, along which rods 3. The shaft 15 protrudes from the cylindrical body 25, protruding in two directions along the feed line 4z. The shaft 15 is provided with a piston 26 placed inside the cylindrical body 25, which forms two chambers for loading and unloading the working fluid, preferably consisting of compressed air. The actuator 14 may also be actuated in a manner other than that described above, and may specifically be actuated mechanically and/or electrically.

Two pairs of swivel bearings 27, 16a, 16b are mounted on opposite protruding parts of the shaft 15 and rotatably support two hollow cylindrical drums 29 equipped with axial through holes around the axis 3a of the rod 3.

Rotary end supports 16a, 16b, one for each drum 29, are placed at a distance from the cylindrical main body 25 and are integral with the end parts of the cylindrical shaft 15 with the ability to push in a direction parallel to the axis of the shaft 15. Two pairs of legs 13a; 13b, holding opposite to each other as many pairs of clips 7a, 8a, are placed in the inner hole of each drum 29 between, on the one hand, the annular element 12a, 12b of the drum 29, having a conical surface converging on the axis 3a of the rod 3; and, on the other hand, the swivel end support 19a, 19b of the shaft 15.

As can also be seen in the drawings in FIG. 4 and 9, legs 13a, 13b; 13c are plate-shaped, their contours extending in their flat plane in a wedge-shaped design. The wedge-shaped contours correspond to the complementary structure of the elements 12a, 12b of the two cylindrical drums 29. Indeed, said elements 12a, 12b have surfaces 17a,

17b, complementing the wedge-shaped structure, which is combined with their wedge-shaped contours and also converges to the axis 3a of the rod 3.

Due to their lamellar shape and due to the connection with the surfaces 17a, 17b of the elements with which they come into contact, the two legs 13a, 13b are such that they extend along their own flat planes in accordance with the parallel planes 4z, 4x, while the legs 13c pass in accordance with their own even planes along the plane 4z, 4y, transverse and orthogonal with respect to the previous one.

In FIG. 5 also shows that elastically deformable stopping means, preferably actuated by coil springs 18a, 18b, are located between the end supports 16a, 16b, which transmit the force of the shaft 15, and the legs 13a, 13b, which receive it.

Comparative examination of FIG. 5 and 7 shows that in use, once the drive 14 which moves the shaft 15 is driven, for example, in the direction of the center line of the cylindrical frame 5 of FIG. 7, the end support 16a exerts a pushing force translationally in the direction of the spring 18a and against the resistance of the annular surfaces 12a, 12b. This results in a sliding translational movement of the wedge-shaped paws 13a; 13b. One such sliding component causes the arms 13a to approach; 13b to feed line 4z. Simultaneously with this translational movement and through the action of the same and only drive 14, the clamps 13a, 13b clamp the outer surface of the rod 3 on which they are located. Clamping takes place in two different zones 10a; 10b gripping rod 3.

In FIG. 6 shows that by equipping, for example, the right free latch with a pair of additional legs 13c in a plane orthogonal to the plane on which the legs 13a, 13b shown in FIG. 5 and 7 are located, and by means of these additional legs 13c, also attached to the same conical element 12b of the right drum 29 shown in FIG. 8, the same action, by means of the shaft 15, clamps an additional pair of clamps 9a, operating along an axis 4y orthogonal to the aforementioned first axes 4z, and 4x (cf. Figs. 6 and 8).

Compared to the prior art, the support and grip unit 2 described above has many advantages over the bar feeder 1.

The first advantage of the presence of the support block 2 and the gripping of the rods 3 is that, due to the high bending stiffness locally provided to the rod 3, only its presence, including in simplified embodiments made with only one clamping element 7; 8 creates a condition of greater static uncertainty which, by creating a sort of sectioning effect, reduces the free bending length of the rod 3. This makes it possible to shift the bending vibration triggering condition to a higher angular speed of the machine tool spindle.

This effect, which is already positive in itself, is greatly increased considering that, in addition to reducing the length of the free bend section of the rod 3, the interlocking effect caused by the presence of the support and catch block 2 can also be enhanced. Indeed, constructively speaking, keeping the zones 10a; 10b of gripping sufficiently far apart along the feed line 4z, the interlocking effect can be greatly influenced by changing its effectiveness according to need.

If we add, which is indeed the case in the example described, the third clamp 9a, perpendicular to the two pairs of clamps 7a, 8a, it can be understood that the interlocking effect is transformed from two-dimensional to three-dimensional in such a way as to counteract the deflection of the rod 3 both in the vertical plane 4z, 4x, and in the horizontal plane 4z, 4y. This is particularly advantageous when it comes to reducing the risk of bending vibrations occurring in the rod 3 with mass eccentricity and/or shape eccentricity.

An additional advantage afforded by the effective stiffness brought about by the presence of the support and grip unit 2 is the possibility of also removing the lubrication system in the channels through which known feed rods are fed. Indeed, the convenient modification of the sectioning reinforcing element provides optimal fastening conditions for supporting the machined rod without the need for continuous abutment against the channel of the bar feeder 1; this eliminates the need to counteract the effect of friction by using a lubricant.

Another equally important advantage of the invention is that in any case it provides the possibility of complete and optimal clamping with perfect alignment with the axis of rotation of the spindle of a machine tool and without jamming the rods 3 for any shape and size of the guide channel of the rod 3. This eliminates the need for disassembly and re-assembly of channels of different shapes and sizes, or alternatively eliminates the need to put up with all the disadvantages caused by jamming due to the rod 3, which is too small when directed along

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Claims (14)

overly wide channel. In addition, the bar feeder 1 according to the invention is advantageously able to work under optimal conditions with bars that are not round in shape, such as multi-sided bars, for example hexagonal or even rectangular, due also to the assistance of the spring 18a present. Indeed, provided, for example, that a rod 3 with a rectangular cross section is to be machined, if two clamps working with a rod 3 of a larger size reach the clamping position, for example, clamps 13a, 13b, while clamps 13c, hypothetically designed to clamp a smaller rod 3 size remain open and separated, the pushing action of the actuator 14 through the still open clamps 13c continues unhindered. Indeed, if the clamps 13a, 13b are already in the clamped position, the springs 18a, with their resilience, compress under load, thus indicating that it can be excluded that said clamped clamps 13a, 13b strongly prevent the shaft 15 from continuing its movement, which is still needed to complete the clamping action of the clamps 13c remaining open. In other words, the springs 18a allow the successive closing of the jaws, which are fully actuated by a single actuator 14. This becomes evident, for example, in FIG. 9, which shows that the clamps 13a, 13b are clamped first, while the clamps 13c are clamped second. Therefore, even with bars with non-circular contours, parts with different cross-sections are always clamped completely and under optimal conditions. This obviously allows the machine tool to operate at the highest operating speeds even with thin rods and/or non-circular sections. Many changes can be made to the invention without departing from the scope of the following claims. One of these changes is illustrated only as a non-limiting example in FIG. 10-12. In FIG. 10 shows that a block 2 for supporting and gripping rods 3, preferably having, but not limited to, one latch 11a; 11b; 11c of tubular shape, mounted on a carriage 33 supported by a pair of linear guides 30 parallel to the feed line 4z, moved along them in both of their directions by actuating the relative mechanization means 31, 32, which include a mechanism 31 with a screw-nut transmission connected with a carriage frame 33 and driven by a gear motor 32. The rod 3 can also be allowed to move along the feed line 4z together with the carriage 33 by appropriately coordinated commands in the time phase between: (i) controlled translational movement of the block (2); (ii) temporarily clamping or unclenching the rod (3) by means of the clamps of the retainer (or retainers) 7a themselves; 8a; 9a or through those of any other similar blocks 2 that may be present (for example, in Fig. 10, 11); or (iii) also in connection with the clamping or unclamping of the rod 3 by means of the lathe spindle. Thus, the auxiliary block 2 shown in FIG. 10 can therefore have double possibilities, on the one hand, to: (i) be able to position along the rod 3 to assume a locally determined position where it optimally contributes to the fastening of the rod 3 by influencing its free bending lengths which, as mentioned above, affect the vibrations of the rod (cf. Fig. 10, 11); and, on the other hand (ii) perform the task of positioning the rod 3 in the longitudinal direction relative to the spindle. Indeed, after gripping the rod 3, the block 2, by means of translational movement along the guides 30, is able to determine the length of the part of the rod 3 that is to be suspended in the machining section of the machine tool. The block 2, which is movable on the carriage 33 shown in FIG. 10-12, thus replacing other parts of the machine tool installed for this purpose, such as the ferrule and stopper, which are well known to those skilled in the art, also reproduce exactly the same functionality as these other parts, but with a distinctly higher activation speed. This allows the operator to combine all the advantages inherent in the block 2 according to the invention, as well as providing the additional advantage of being able to perform the necessary positioning operations that determine the time interval between the machining of two successive sections of the bar 3, with significant savings in terms of cycle time and , therefore, with a significant reduction in machining costs. CLAIM 1. Block (2) of support and capture of rods (3), which feeds, sequentially in the axial direction relative to each other, along the feed line (4z) of a mechanical machine, containing at least one latch (11a; 11b; 11c) in the tubular assembly form, running parallel to the feed line (4z); wherein the latch (11a; 11b; 11c) assembly is attached to the periphery of the rod (3), which passes through the through hole (6) inside the latch (11a; 11b; 11c) assembly, while the axis (3a ) rod (3), coincides with the axis of the tubular hole (6) and at least one element (7; 8) for clamping, provided with at least one pair of clamps (7a; 8a; 9a), which can clamp the rod (3 ) in at least one gripping zone (10a; 10b; 10c) located along the line (4z), while said at least one clamping element (7; 8) contains a drive (14) and at least one stepped stop bearing (16a; 16b) attached to at least one foot (13a; 13b; 13c) of the specified at least one retainer (11a; 11b; 11c), while the specified element (7; 8) for clamping is able to do the specified at least one latch (11a; 11b; 11c) and the specified rod (3) as a mutually integral whole, while the specified support and grip block (2) is characterized in that the specified the drive (14) comprises a tubular shaft (15) traversed in the axial direction by said rod (3) and which is movable in translation in both directions relative to the axial line (3a); wherein said or each stepped thrust bearing (16a; 16b) mounted on the shaft (15) is supported by at least one paw (13a; 13b; 13c) of said at least one retainer (11a; 11b; 11c). 2. Support and gripping unit according to claim 1, characterized in that said at least one clamping element (7; 8) is contained in an inner hole (6) of said at least one retainer (11a; 11b; 11c). 3. The block of support and grip according to claim 1 or 2, characterized in that said at least one element (7; 8) for clamping contains at least one pair of clamps (7a; 8a; 9a), which have gripping surfaces, having a shape which has a profile which embraces the outer part of the rod (3) and which are movable in directions (4x; 4y) transverse to the line (4z). 4. The support and grip unit according to claim 3, characterized in that said at least one latch (11a; 11b; 11c) contains at least one annular element (12a; 12b) of the thrust bearing and at least one wedge-shaped paw ( 13a; 13b; 13c) supporting at least one pair of clamps (7a; 8a; 9a) located between said at least one annular element (12a; 12b) and the rod (3) and connected along the axis, and in accordance with the direction of at least one surface (17a; 17b), complementing the annular element (12a; 12b), which converges to the axis (3a) of the rod (3). 5. Support and grip unit according to claim 1, characterized in that said drive (14) can be driven using a fluid medium. 6. Block support and capture according to any of the previous paragraphs, characterized in that the specified at least one element (7; 8) for clamping contains elastically deformable stopping means (18a; 18b), controlled by the specified drive (14) and in response to clamping action of at least one pair of clamps (7a; 8a; 9a) of said one or each clamp element (7; 8). 7. A support and gripping unit according to any one of the preceding claims, characterized in that it comprises at least two said latches (11a; 11b; 11c) arranged in series relative to each other along the supply line (4z). 8. Block according to claim 7, characterized in that said two clamps (11a; 11b; 11c) are combined to clamp the rod (3) using at least two said paws (13a; 13b; 13c) functioning along the plane (4z , 4x). 9. Block according to claim 6, or 7, or 8, characterized in that at least two said paws (13; 13b; 13 c) operate in mutually perpendicular planes (4z, 4x; 4z, 4y). 10. Block according to any one of claims 6 to 9, characterized in that it contains three said paws (13a; 13b; 13c) located along the outer part of the rod (3) in at least one zone (10a; 10b; 10c) gripping rod (3). 11. Block according to claim 1, characterized in that said actuator (14) is unique to said at least one latch (11a; 11b; 11c). 12. A support and gripping unit according to any one of the preceding claims, characterized in that said at least one clamping element (7; 8) can be controlled remotely. 13. Block support and capture according to any of the previous paragraphs, characterized in that it contains at least one carriage (33)supporting at least one specified latch (11a; 11b; 11c); guides (30) supporting said carriage (33); and means for mechanization (31; 32) of said one or each carriage (33) along the guides (4z). 14. Bar feeder (1), characterized in that it comprises at least one bar support and gripping unit (2) (3) as defined in at least one of the preceding paragraphs. -