AUTOMATIC LOADER FOR MACHINE TOOLS

Abstract: An automatic loader for positioning a piece to be worked (22) on a machine tool (1) comprises a movable feed member (17) for conveying the piece to be worked (22) to a working seat (2) of the machine tool (1). The movable feed member (17) has a support (20) for the piece (22) which is displaceable relative to the movable member (6) against the action of resilient damping members (25, 27) when, as a result of the approach of the movable member (17) to the seat (2) of the machine tool (1) along a first path (Y), the piece to be worked (22) does not fit correctly into its seat (2), so as to cushion the contact between the piece (22) and the seat (2) and allow the approach movement to be repeated along subsequent paths (Y1, Y2, X) parallel to the first path (Y) until the fit is correct.

Description: Automatic loader for machine tools. The present invention relates to an automatic loader for machine tools and particularly for gear-shaving machines. The object of the invention is to provide a loader which is more efficient than the known loaders of the prior art and, in the particular case of application to gear-shaving: machines, enables the step of meshing the gear to be shaved with the shaving cutter to be effected safely and without risk of damage to the teeth of the gear and the shaving cutter. This object is achieved by the characteristic which constitutes the subject of Claim 1 below. Further characteristics and advantages of the present invention will become apparent from the description which follows with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is an elevational view of an automatic loader for gear-shaving machines,according to the present invention. Figure 2 is a plan view of Figure 1, Figure 3 illustrates a detail of Figure 2 on an enlarged scale. Figure 4 is a perspective view of a detail of the conveyors illustrated in Figures 1 and 2, Figure 5 is a perspective view of a variant of Figure 4 and Figure 6 is schematic view illustrating the- step of meshing a gear to be shaved with the shaving cutter. In the example illustrated in Figures 1 to 4, a gear-shaving machine is indicated 1 and has a shaving cutter 2 in the form of a toothed wheel rotated about a horizontal axis 3. The machine 1 further includes means, generally indicated 4, for supporting a gear to be shaved, indicated 22, for rotation about a horizontal axis 5 inclined to and below the .axis 3,the gear 22 meshing with the teeth of the shaving cutter 2 and being pressed against the cutter as a result of an upwardly-exerted force. A loading unit, generally indicated 6, is adjacent the shaving machine 1 and includes a base 7 having horizontal guides 8 on which a slide 9 is slidable in a direction perpendicular to the axis 5. The movement of the slide 9 in both directions is driven by a motor 10 which operates a screw 11 engaged with a nut, not shown, carried by the slide 9. A circular platform 12 is rotatably mounted on the slide 9 about a vertical axis. The platform 12 is rotated by a motor 13 which drives a sprocket 14 meshing with external teeth 15 of the platform 12. Vertical guide columns, indicated 16, are carried by the rotatable platform 12 and are connected at their upper ends by a circular plate 16a. A support beam 17 is slidable vertically on the columns 16 and its vertical movement in both directions is driven by a motor 18 through a screw 18a which engages a nut 18b carried by the beam 17. Each of the two ends of the support beam 17 * is articulated about a horizontal pin 19 to a rocker arm 20 provided at its upper end with a cradle-shaped seat 21 for supporting a gear 22. The inner end of each rocker arm 20 is articulated about a horizontal pin 23, as illustrated in particular in Figure 3, to the lower end of the rod 24 of a piston 25 sealed for sliding in a cylinder 27 by means of a washer 26. The cylinder 27 is closed at its upper end by an end wall 28 and at its lower end is articulated about a pin 29 to a forked support 30 carried by the beam 17. The chamber 31 of the cylinder 27 between the piston 26 and the wall 28 is filled with a pressurised gas, for example air, supplied through a feed duct 32 and a pressure regulator 33 having a knob 34 for adjustment of the pressure. A manometer for indicating the pressure in the chamber 31 is indicated 35. The pressure in the chamber 31 is regulated by means of the regulator 33 in dependence on the weight of the gear 22 supported in the seat 21 of the rocker arm 20. An adjustable vent valve 43 is fitted to the wall 28 of the cylinder 27. This valve could also be incorporated in the pressure regulator 33. A microswitch 36 is carried by the forked support 30 so as to be operable as a result of a predetermined degree of oscillation of the arm 20 about the pin 19 in the clockwise sense with reference to Figure 3. A loading conveyor and an unloading conveyor, indicated 37a and 37b respectively, are located above one another at the side of the loading unit 1 described above. Each of the two conveyors 37a, 37b includes a plurality of plates 38 articulated together and each supporting, by means of a central support 38a, a transverse pin 39 which carries the gears 22. When the gears to be shaved are already mounted on a shaft, the conveyors 37a and 37b will be provided with the supports illustrated in Figure 5. These supports comprise plates 40 articulated together and carrying supports 41 with V-shaped notches 42 for receiving the shaft 22a of the gear 22. Obviously, in this case, the rocker arms 20 are also provided with pairs of supports similar to those illustrated in Figure 5 instead of the cradle-shaped supports 21. The operation of the automatic loader described above is as follows. In the position illustrated in Figure 1, the gears 22 carried by the conveyor 37a are supplied to the seat 21 of the rocker arm 20 which faces the conveyor- 37a. The other arm 20 opposite the loader 37a contains a gear 22 which has already been shaved. As a result of a 90° rotation of the beam 17, the gear 22 to be shaved is placed beneath the shaving cutter 2 in the position illustrated in Figure 6, in which the axis Y of the gear 22 is spaced from the working position X (corresponding to the axis indicated 5 in Figure 2 ) by a distance A. The distance A between the points Y and X corresponds essentially to the distance between the heads of two consecutive teeth of the gear 22. The motor 10 which controls the movement of the slide 9 in the direction of the arrow F is actuated, as are the other motors which control the various movements of the loading unit, by a control unit which is preferably a nunerlcal cαtrol unit so as to make the slide 9 and hence the guide 22 effect a sequence of displacements each corresponding to a fraction of the distance A. In the embodiment illustrated, each displacement corresponds to a third of the distance A whereby the axis of the gear 22 moves in sequence into the intermediate positions indicated Yl and Y2 before it reaches the final position, indicated X. In each of these positions, the advance of the slide is stopped and the gear 22 is moved vertically as a result of the vertical movement of the beam 17 controlled by the motor 18. if the teeth of the gear 22 mesh with those of the cutter 2 on the first vertical movement, the slide 9 effects a further axial movement to bring the axis of the gear into the position indicated X and- the shaving is started as a result of the rotation of the shaving cutter 2. If the teeth of the gear 22 come into head to head contact with those of the shaving cutter 2 during the upward movement of the gear 22, however, this contact causes rotation of the rocker arm 20 about its pin 19 and the consequent raising of the piston 25 in the cylinder 27 as a result of the upward movement of the beam 17. The gas in the chamber 31 is compressed until the predetermined pressure controlled by the valve 43 is reached. Thus, the contact between the heads of the teeth is cushioned by the compressed gas in the chamber 31, avoiding damage to the gear and the shaving cutter. The oscillation of the rocker arm 20 causes the closure of the microswitch 36 which stops "■"" he upward di_rplacan€_-t of the beam 17. At -this point, -t±e r__rnerlcal cαtrol unit of the machine causes the descent of the beam 17 by a predetermined distance and the subsequent movement of the slide 9, to bring the axis of the gear from the position Y to the position indicated Yl , and the cycle is repeated until meshing occurs, after which shaving starts. The gear which has just been shaved is placed onto the unloading conveyor 37b by the loading unit as a result of the combined movements of the loading unit. Although the above description has referred to the use of a gas spring as the means for balancing the weight of the gear and absorbing any shocks which could occur in the meshing stage, the present invention is not intended to • be limited to the use of this type of spring. In fact, hydraulic dampers or metal springs the load of which is adaptable to the weight of the gear to be shaved could be used instead of the gas spring.

Claims: CLAIMS 1. Automatic loader for positioning a piece to be worked on a machine tool, comprising a movable feed member for conveying the piece to be .worked to a working seat of the machine tool, characterised in that the movable feed member has a support for the piece which is displaceable relative to the movable member against the action of resilient damping members when, as a result of the approach of the movable member to the seat of the machine tool along a first path, the piece to be worked does not fit correctly into its seat, so as to cushion the contact between the piece and the seat and allow the approach movement to be repeated along subsequent paths parallel to the first path until the fit is correct. 2. Automatic ' loader according to Claim 1, for gear shaving machines having a shaving cutter in the form of a toothed wheel rotated about a first horizontal axis and means for supporting a gear to be shaved for rotation about a second horizontal axis inclined to the first axis, the gear to be shaved meshing with the teeth of the shaving cutter and being pressed against the blade, characterised in that it comprises: a loading unit adjacent the shaving machine, feed conveyor means for supplying the gears to be shaved to the loading unit, unloading conveyor means for conveying the shaved gears from the loading unit to an unloading station, the loading unit including: a base, - a slide slidable relative to the base along a third horizontal axis perpendicular to the second horizontal axis, means for moving the slide in two directions for moving it towards and moving it away from the shaving machine, a rotatable platform supported by a slide so as to be rotateble about a vertical axis, - means for rotating the platform, a plurality of vertical guide columns carried by the rotatable platform, a horizontal support beam slidable vertically on the guide columns, - means for moving the support beam vertically in two directions on the guide columns, a rocker arm articulated to each of the two ends of the support beam about a horizontal axis, each of the rocker arms having a seat at its outer end for supporting a gear and being subject at its inner end to the action of resilient means reacting on the support beam, means for adjusting the load of the resilient means in dependence- on the weight of the gear supported by the rocker arm, whereby, as a result of the combined movements of the slide relative to the base, the platform relative to the slide, and the beam relative to the columns carried by the platform, the two rocker arms act as transfer members for transferring a gear to be shaved from the feed conveyor to the shaving machine and for transferring a shaved gear from the shaving machine to the unloading conveyor, respectively, switch means carried by the beam and operable by the rocker arm which carries the gear to be shaved as a result of a predetermined angular displacement of the rocker arm, the resilient means acting as shock-absorbers when, as a result of the raising of the beam, the heads of the teeth of the gear to be shaved come into contact with the heads o"f the teeth of the cutter and the rocker arm is angularly displaced to cause the closure of said switch means; the closure of said switch means causing the stopping of the ascent of the beam, the lowering of the beam, an axial movement of the slide towards the shaving πachiπe ttirσq a p-recte-tea-mined distance and a subsequent raising of the beam until the correct position is reached. 3 . Loader according to Claims 1 and 2 , characterised in that the resilient means are constituted by a gas spring . 4. Loader according to Claim 3, characterised in that the gas is air. 5. Loader according to Claims 2 and 3, characterised in that the inner end of each rocker arm is articulated to the lower end of the rod of a piston slidable in a substantially vertical cylinder which is closed at its upper end by an end wall and is articulated to a support carried by the beam, the upper chamber of the cylinder between the piston and the wall being connected to a source of compressed gas through a pressure regulator and to the atmosphere through a calibratable vent valve. 6. Loader according to Claims 1 and 2, characterised in that the resilient means comprise a metal spring and means for setting the load of the spring. 7. Loader according to Claims 1 and 2, characterised in that the resilient means include a hydraulic damper.

Inventors: BETTOCCHI ETTORE, BETTOCCHI, ETTORE
Applicants: METALCASTELLO SRL, METALCASTELLO S.R.L.
Application year: 1986
Main classification: B23F23
IPC codes: B23F19, B23F23, B23Q7