Hydraulic coupling for feeding fluid-driven actuators, particularly hydraulic motors, mounted on a rotating structure

Abstract: A hydraulic coupling for feeding hydraulic actuators, particularly for distributing pressurized oil to a plurality of hydraulic motors (8) mounted on a rotating structure such as a drum feeder for feeding bars to an automatic multispindle lathe; the motors (8) are angularly distributed around the rotation axis of the structure, and the coupling (13) comprises a plurality of ducts which branch out axially from the structure and are angularly distributed with respect to the rotation axis; the ducts are connected to the delivery and the return of the motors at one end and, at the opposite end, by means of respective flexible hoses (21), to a stationary distributor (22) for connecting the motors to a source of pressurized oil and to the oil discharge; the flexible hoses are arranged in a spiral around the rotation axis and have a length which allows the rotation of the structure with respect to the distributor through a preset angle; the distributor comprises valves for controlling the flexible hoses which are actuated so as to connect the intake and discharge of oil to and from the motors according to a programmed sequence.

Description: The present invention relates to a hydraulic coupling for feeding fluid-driven actuators, particularly for distributing pressurized oil among a plurality of hydraulic motors mounted on a rotating structure. The invention can be used in particular in drum feeders for feeding bars to multispindle automatic lathes. Conventionally a multispindle automatic lathe is a machine tool comprising a plurality of machining stations which are distributed around a horizontal axis and in which specific machining operations are performed on a bar fed by a feeder. These machinings are, for example, screw cutting, turning, end-facing, parting and so forth. The bar feeder is substantially constituted by a drum which is rotated about said horizontal axis by said lathe and comprises a plurality of concentric tubular guides which are angularly distributed around the rotation axis; an advancement device is associated with each guide and causes the advancement of the bars, taken from a magazine and inserted in the guides, toward the lathe. At the end of each individual machining, the drum rotates by the same angle that lies between the individual stations, so that the front ends undergo successive machinings. After the drum has completed a rotation through 360°, the machining cycle is complete and the machined part is removed, while a new bar segment is made to advance toward the lathe to undergo the intended machinings. It is known to use, as a device for the advancement of each bar in the corresponding guide, a chain or another similar element provided with a bar pusher sliding in the guide and actuated by a fluid-driven motor. The pressurized fluid is distributed to the individual motors by using a rotary distributor which is mounted on the rotation axis of the drum and is provided with mechanical devices for controlling the delivery and return of the oil that feeds the motors. Conventional rotary distributors entail the drawback that they do not allow optimum use of the machining stations of the lathe in case of very simple machinings of the parts. For example, if the simple parting of parts from a bar and the forming of a bore at one end are required, most of the machining stations are not used and act only as transit stations. A bar feeder with a rotating drum and a plurality of hydraulic motors is disclosed by EP-A-338 606, which discloses a hydraulic coupling according to the preamble of independent claim 1. The aim of the present invention is to provide a hydraulic coupling for feeding fluid-driven actuators which allows to vary at will the number of stations in which the bars to be machined are advanced, so as to increase the number of stations in which machinings are performed and thus fully utilize the production capacity of the lathe. Within the scope of this aim, an object of the present invention is to provide a coupling which is structurally simpler than conventional rotary couplings and is therefore cheaper and safer in operation. This aim and this object are achieved with a hydraulic coupling for feeding hydraulic actuators, particularly for distributing pressurized oil to a plurality of hydraulic motors mounted on a rotating structure, such as a drum feeder for feeding bars to an automatic multispindle lathe, said actuators being angularly distributed around the rotation axis of said rotating structure the coupling comprising a plurality of flexible hoses-and ducts, said ducts being connected to the delivery and the return of said actuators at a first end and, at the second, opposite end to a stationary distributor for connecting said actuator to a source of pressurized oil and to the oil discharge, whereby said ducts branch out axially from said rotating structure are angularly distributed with respect to said rotation axis, and are connected to said stationary distributor through said flexible hoses which are arranged in a spiral around said rotation axis and have a length which allows the rotation of said rotating structure with respect to said distributor through a preset angle, said distributor comprising valves for controlling said flexible hoses which are actuated so as to connect the intake and discharge of oil to and from said actuators according to a programmed sequence. Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a longitudinal sectional view of a coupling for feeding pressurized oil to multiple hydraulic motors mounted on a drum feeder for feeding bars to a multispindle automatic lathe; Figure 2 is a transverse sectional view, taken along the plane II-II of Figure 1; and Figures 3 and 4 are two perspective views of the coupling. With reference to the above figures, the reference numeral 1 designates the opposite drum feeder end with respect to the end that is associated with a multispindle automatic lathe which must be fed with bars taken from a containment magazine. The reference numeral 2 designates one of the two vertical sides that limit the frame at the opposite ends and support the rotating part, or drum, of the feeder. Said drum comprises a tubular beam 3; two respective circular center bearings are centered and fixed to the opposite ends of said beam, and only one of said center bearings, designated by the reference numeral 4, is visible in the drawing. The center bearings 4 roll on sets of three rollers 5 which cantilever out from the sides 2 so that the drum can rotate about the horizontal axis A. The guides 6 of the bars to be fed to the lathe lie between the center bearings 4, parallel to the axis A, and are angularly distributed around the axis A. The guides 6 are generally constituted by two half-shells which can be mutually spaced in order to allow the feeding of the bars to be machined. The advancement of each bar in the respective guide 6 is actuated by a bar pusher, which is coupled to a flexible traction element 7 lying to the side of the guide, parallel thereto. The flexible elements 7, which in the illustrated example are constituted by toothed belts, are actuated by respective hydraulic motors 8 mounted on L-shaped brackets 9 which are fixed in a cantilevered manner to the center bearing 4. The reference numerals 10 and 11 designate pulleys which, for each motor, respectively tension the toothed belt 7 and wind it on the driving pulley 12, which is keyed on the output shaft of the motor 8. In order to connect the motors 8 to a source of pressurized oil and to the discharge there is provided the coupling according to the present invention, which is generally designated by the reference numeral 13 in the drawing. Said coupling 13 comprises a sleeve 14 which is coupled to the center bearing 4 by means of a flange coaxially to the axis A and has an expanded portion 15 in which a plurality of axial ducts 16 is provided and whose number is twice that of the motors 8. The axial ducts 16 are angularly distributed about the axis A and end on the front edge of the expanded portion 15 at one end and end radially with threaded holes 17 and 18 at the opposite end. Axial pipes 19 are screwed into the threaded holes 17 and gradually increase in length. The pipes 19 are thus parallel to the axis A and their ends lie on a line defining a cylindrical spiral around the axis A. The motors 8 are connected to the holes 18. In particular, two holes 18 are connected to the inlet and outlet holes of each motor 8 by means of connecting hoses 20 which conveniently, for assembly reasons, are arranged outside the motors. The axial pipes 19 are connected, by means of flexible hoses 21, to a stationary distributor 22 which is fixed to the frame of the feeder. In order to prevent the pipes 19 from becoming tangled, said pipes are guided through a guiding bracket 22a which rotates with the axial pipes 19. The flexible hoses 21 are connected to the axial pipes 19 by means of L-shaped unions 23 which are orientated so that the flexible hoses 21 are substantially perpendicular to the axis A and tangent to the imaginary cylinder formed by the pipes 19. The length of the flexible hoses 21 is such that they trace a spiral around the axis A, so as to allow, by utilizing the elasticity of the hoses 21, a complete rotation of the sleeve 14 and therefore of the drum of the feeder with respect to the distributor 22. Advantageously, the spirals of the hoses 21 lie on planes which are perpendicular to the rotation axis A. The stationary distributor 22 is connected to a source of pressurized oil and comprises multiple electric valves which are controlled so as to connect the intake and the discharge of the oil toward and from said motors 8 according to a preset program. For example, the distribution of pressurized oil can occur cyclically during the rotation of the drum. The operating prerogatives of the described coupling are the fact that the connection of the motors 8 for the advancement of the bars is not dependent on the rotation of the drum but can be set by programming the opening and closure of the electric valves of the distributor 22. This greater flexibility of the feeder allows to make the bar advance in any station and to vary at will the number of advancement stations. For example, if in a six-station lathe it is necessary to perform machinings which can be performed in just three stations, it is possible to produce the simultaneous advancement of two bars: one is subjected to the machinings of the first three stations, while the other bar undergoes the same number of machinings in the subsequent three stations. When the lathe has ended the machining cycle and has thus covered a rotation angle at the most slightly greater than 360°, it is of course returned to the machining start position by performing a rotation of equal extent in the opposite direction. It should be observed that the described coupling allows machinings according to conventional cycles and with special interventions on the advancement of the bars. For example, during the pauses of the rotation of the drum all the hydraulic motors can remain connected to the source of oil at a reduced pressure, so that the motors, by rotating in one direction, determine a slight thrust on the bars contained in the guides of the drum. Numerous modifications and variations are possible in the practical embodiment of the invention. One of these variations provides, inside the tubular beam 3, a coaxial tubular element 24 which lies inside the sleeve 14 and forms a tubular chamber 25 for collecting the lubricating oil of the rotating bars in the guides 6. The tubular chamber 25 is connected, through an opening 26 formed in the expansion 15 between the axial ducts 16, to an annular cavity 27 formed by a bush 28 which is sealingly mounted in an external seat of the expansion 15. The bush 28 is rigidly coupled to the frame of the feeder and is provided with an outlet 29 for the recirculation of the bar lubrication oil. It should be observed that the tubular structure of the coupling 13 allows the passage, inside the tubular element 24, of electrical cables which, in order to avoid interfering with the pipes 19, are guided through a tubular extension 30 supported by a bracket 31 which is fixed to the frame of the feeder. The disclosures in Italian Patent Application No. BO97A000536 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: A hydraulic coupling for feeding hydraulic actuator (8), particularly for distributing pressurized oil to a plurality of hydraulic motors (8), mounted on a rotating structur (1), such as a drum feeder (1) for feeding bars to an automatic multispindle lathe, said actuators (8) being angularly distributed around the rotation axis (A) of said rotation structure (1), the coupling comprising a plurality of flexible hoses (21) and ducts (16), said ducts (16) being connected to the delivery and the return of said actuators (8) at a first end (18) and, at the second, opposite end (17) to a stationary distributor (22) for connecting said actuators (8) to a source of pressurized oil and to the oil discharge, characterized in that said ducts (16) branch out axially from said rotating structure (1), are angularly distributed with respect to said rotation axis (A), and are connected to said stationary distributor (22) through said flexible hoses (21) which are arranged in a spiral around said rotation axis (A) and have a length which allows the rotation of said rotating structure (1) with respect to said distributor (22) through a preset angle, said distributor (22) comprising valves for controlling said flexible hoses (21) which are actuated so as to connect the intake and discharge of oil to and from said actuators (8) according to a programmed sequence. A coupling according to claim 1, characterized in that it comprises a sleeve (14), which is coupled to the rotating structure (1) by means of a flange coaxially to the rotation axis (A) thereof, said axial ducts (16) being in a number which is twice that of the actuators (8), said ducts (16) being formed in said sleeve (14) and angularly distributed around the rotation axis (A) of said rotating structure (1), said ducts (16) ending, at a second end, on the front edge of said sleeve (14), with threaded holes (17) in which axial pipes (19) are screwed which gradually increase in length, and at a first end, with radial threaded holes (18), said radial holes (18) being connected to the inlet and the outlet of each actuator (8) by means of connecting hoses (20), said axial pipes (19) being connected, by means of said flexible hoses (21), to said stationary distributor (22) which is fixed to the frame (2) of said rotating structure (1), the connection of said flexible hoses (21) to the axial pipes (19) being provided by means of couplings (23) which are such that said flexible hoses (21) are tangent to the imaginary cylinder formed by said axial pipes (19) and lay in planes which are substantially perpendicular to said rotation axis (A) of the rotating structure, the length of said flexible hoses (21) being such that they trace a spiral around said rotation axis (A) such as to allow, due to the elasticity of said flexible hoses (21), a complete rotation of the sleeve (14) and therefore of the rotating structure (1) with respect to the distributor (22). A coupling according to claim 2, characterized in that said stationary distributor (22) is connected to a source of pressurized oil and comprises multiple electric valves which are controlled so as to connect the intake and the discharge of the oil toward and from said actuators (8) according to a preset program. A coupling according to one of claims 2 and 3, characterized in that said rotating structure (1) comprises a tubular beam (3) inside which a coaxial tubular element (24) is provided which lies inside said sleeve (14) and forms a tubular chamber (25) for collecting the lubrication oil for the bars that rotate in the guides (6) of the rotating structure (1), said tubular chamber (25) being connected, through an opening (26) formed in said sleeve (14) between said axial ducts (16), to an annular cavity (27) formed by a bush (28) fitted hermetically in an external seat of said sleeve (14), said bush (28) being rigidly coupled to the frame (2) of the rotating structure (1) and having an outlet for recirculating the bar lubrication oil. A coupling according to claim 4, characterized in that it comprises a tubular extension (30) of said tubular element (24) which lies coaxially between said axial pipes (19), in order to allow the external passage of electrical cables guided along said tubular beam (3) and said tubular element (24).

Inventors: DREI ANDREA, MINGOZZI RENATO, NENNI ENRICO, DREI, ANDREA, MINGOZZI, RENATO, NENNI, ENRICO
Applicants: IEMCA GIULIANI MACCHINE ITALIA, IEMCA GIULIANI MACCHINE ITALIA S.P.A.
Application year: 1998
Main classification: B23Q1
IPC codes: B23B13, B23Q1, F16L27