FR2918592A1 - Rotating tool-carrying spindle displacing device for e.g. automatic industrial drilling machine, has inner screw thread connected in driving relationship with engine units to rotate sleeve along same direction similar to that of spindle - Google Patents

Abstract

The device has an inner screw thread (19) connected to engine units comprising a shaft (29), a feed drive gear (34), a feed driven gear (37), a return drive gear (38) and a return driven gear (41). The screw thread is connected in a driving relationship with the engine units to rotate a feed drive sleeve (9) along a same direction similar to that of a rotative tool-carrying spindle (13) for axial return of the spindle. The spindle is threaded with the sleeve at the screw thread connected to the engine units by rotative transmission units.

Description

DESCRIPTION Device for axial displacement of a rotating spindle,

  The present invention relates to a device for axial displacement of a rotating spindle.

  The present invention also relates to a spindle equipment 10 equipped with the axial displacement device.

  The present invention also relates to a machining apparatus thus equipped, in particular an automatic drill for industrial use, equipped with the device or equipment.

  Such machining devices typically include a rotating motor gear which meshes with a driven rotating gear. The latter has a grooved bore which receives the pin, which is correspondingly grooved.

  There is also an advance motor gear which is coaxial with the rotating motor gear and which can be either clutched with the rotating motor gear to be driven by the latter, or declutched thereof and clutched on a fixed part. . The feed motor pinion has a nominal diameter a little larger than the rotation motor gear and meshes with a pre-driven gear which thus rotates a little faster than the driven idler gear. The driven rotating gear is formed around a bushing which has a threaded bore cooperating with a corresponding thread provided on the spindle in areas which are not hollowed by the splines. The spindle feed is equal, for a spindle revolution, to the pitch of the thread multiplied by the percentage of overspeed of the pre-driven gear.

  At the end of the advance stroke, a rear flange of the spindle abuts on the rotational driven gear rotating at the same speed. This stop phenomenon prevents the spindle from continuing its advance movement, and thus prevents the pre-driven gear from continuing to rotate faster than the spinning driven gear. This resistance to rotation of the bushing results in an increase in the rotational torque transmitted by the drive gear. Due to a specific arrangement of the clutch, the increase in the transmitted torque has the effect that the drive gear of advance is disconnected from the rotating motor gear by performing a slight axial movement of repulsion relative thereto. The axial movement of repulsion activates a pneumatic actuator. The piston of the actuator is coupled to the drive motor pinion and leads the latter in a dogging against a fixed part. The rotation of the spindle continues in the same direction. This results in a rapid unscrewing movement through the pre-driven gear that is now immobilized. This is how we ensure the rapid return of the tool at the end of the drilling operation.

  Current machines of this type have drawbacks that increase with the speed of rotation of the spindle. The blocking of the drive motor gear and the driven gear at the end of the machining stroke produces a shock which is all the more violent as the rotational speed is high. In addition, the return stroke is performed faster than the rotation of the spindle is fast. However, the system that is generally designed to stop the motor end of the return stroke is more expensive and / or less effective to react accurately to the end of the race when the axial speed of the spindle is high The purpose of the invention is thus to propose an axial displacement device which allows a very fast rotation of the spindle without the result of problems of shock and / or excessive speed during the axial return of the spindle at the end of its movement beforehand.

  According to the invention, the device for axial displacement of a spindle driven in rotation, in which the spindle is in thread engagement with at least one internally threaded bushing connected to motor means by rotary transmission means, with between bushing and spindle a first rotational speed difference to generate an axial feed of the spindle, while an axial return movement of the spindle is generated by imposing between the internal thread and the spindle a second difference in speed in the opposite direction to the first difference of speed, is characterized in that for the axial return said thread is in drive relation with the motor means to rotate in the same direction as the spindle.

  Thus, instead of blocking the bushing to generate an extremely fast return movement when the rotational speed of the spindle is high, a kinematic connection is made between the bushing and the motor means which rotates the bushing in the same direction as the bushing. brooch. This kinematic connection generates, between bushing and spindle, a speed difference which is in the opposite direction to that generated between bushing and spindle for the feed movement. In addition, the speed difference for the return movement is chosen so that the axial return speed of the spindle has a suitable value. Typically, this difference in speed is generated by an appropriate transmission ratio in the kinematic link, taking into account the speed of rotation of the drive means and the thread pitch of the spindle.

  The choice of an appropriate speed difference makes it possible to obtain a reasonably fast return of the spindle even when the spindle rotates at very high speeds, for example greater than 4000 or even 7000 revolutions per minute. It is thus possible to provide for the spindle rotational speeds as high as may otherwise be desirable without resulting in excessive brutality and speed of the return movement of the spindle, or a shock in the device during the passage from the advance movement to the return movement.

  According to the second aspect of the invention, this relates to a spindle equipment, typically intended to be attached to a pneumatic engine block, to constitute with this engine block a rotary machining apparatus, in particular an automatic drill. for industrial use.

  The invention is aimed in particular at industrial machining apparatus which must be positioned on the machining site before carrying out a machining operation, for example a drilling, especially in the context of the manufacture or the assembly of very large parts, such as airplanes. Typically, the part to be manufactured or assembled is associated with a mounting, called a grid, on which the machining apparatus can be accurately positioned at each point where a machining, for example a drilling, must be performed.

  According to a third aspect of the invention, this relates to a rotary machining apparatus provided with a device according to the first aspect or an equipment according to the second aspect.

  Typically, this device is an automatic drill for industrial use. Other features and advantages of the invention will emerge from the description below, relating to a non-limiting example.

  In the accompanying drawings: FIG. 1 is a general view of an automatic drill according to the invention, with axial section of the equipment according to the invention, the clutch being in position of axial movement in advance of the spindle; ; Figure 2 is a top view of the spindle and the driven rotating drive gear; - Figure 3 is a view similar to Figure 1 but partial and with the clutch leaving its position of axial movement in advance of the spindle; and FIG. 4 is a view similar to FIG. 3, but with the clutch in the axial return position of the spindle.

  The automatic drill for industrial use shown in Figure 1 comprises a motor block 1 which is only very schematically and partially shown and a spindle equipment 2. The engine block 30 is typically pneumatic. Its output shaft, not shown, is coupled in rotation with an input shaft 3 of the equipment 2. The input shaft 3 is rotatably supported in a frame 4 of the equipment 2. The frame 4 supports also in rotation along a spindle axis 6, on the one hand a driving pinion in rotation 7 in a bearing 8 and on the other hand a feed control sleeve 9 in a bearing 11. The driven pinion 7 and the bushing 9 are associated by an assembly 12 which allows them to rotate relative to each other about the spindle axis 6 while resting on each other with respect to their centering mutual and their mutual axial positioning. The bearings 8 and 11 immobilize axially the assembly formed by the pinion 7 and the sleeve 9 relative to the frame 2.

  A tool spindle 13, extending along the spindle axis 6, is engaged in a bore 14 of the pinion 7 and in a bore 16 of the sleeve 9. In a manner not shown, the pin 13 carries in use, at its end pointing downwards in Figure 1, a machining tool such as a drill. Pin 13 has on its side wall axial grooves or grooves 17 in which are engaged axially extending teeth 18, formed projecting on the wall of the cylindrical bore 14 (see also Figure 2). The pin 13 further has on its side wall a thread 19 which is threaded with a corresponding thread 21 formed on the wall of the bore 16 of the sleeve 9. As shown in Figure 2, the thread 19 occupies on the side wall of the pin 13 of the angular regions which alternate around the periphery of the pin 13 with those hollowed by the grooves 17.

  An intermediate gear 22, freely rotatable in the frame 4 about an intermediate axis 23 parallel to the spindle axis 6, comprises a first conical gear 24 meshing with a conical input gear 26 integral with the gear shaft. input 3, and a second cylindrical toothing 27, forming a drive pinion in rotation, meshing with the cylindrical toothing 28 of the rotary drive pinion 7.

  Thus, when the input gear 26 is rotated by the shaft of the engine block 1, the driven rotating gear 7, driven in rotation by means of the intermediate gear 22, drives itself into rotation. rotation pin 13 through the teeth 18 engaged in the splines 17 of the spindle.

  The intermediate gear 22 is fixed rigidly to a shaft 29 which constitutes a common drive member for the automatic feed and the automatic return of the spindle 13. In the example shown, a column 31 is fixedly mounted in the frame 4 according to FIG. intermediate shaft 23. The column 31 passes axially through the shaft 29 made tubular and supports the shaft 29 through a bearing 32. The intermediate gear 22, also traversed by the column 31, is fixed to the shaft 29 through a thread 33. The assembly is such that the bearing 32 immobilizes axially on the column 31 the assembly formed by the intermediate gear 22 and the shaft 29.

  Between the tubular shaft 29 and the bushing 9 there are two motion transmission paths, with two different transmission ratios, to give the bushing 9 and therefore the spindle 13 a rotational speed which is either greater or greater. much smaller than that of the rotating drive gear 7.

  Given the direction of rotation of the pinion 7, defined by the direction of rotation of the pneumatic motor located in the body 1, and the direction of the threads 19 and 21 of the pin 13 and respectively of the sleeve 9, the pin 13 is subjected to an axial movement in advance when the sleeve 9 rotates faster than it, and an axial return movement when the sleeve 9 rotates slower than it.

  The forward motion transmission path comprises a feed motor pinion 34 which is freely rotatably mounted but axially immobilized on the shaft 29 by means of a bearing 36. The feed motor pinion 34 meshes with a driven pinion. a feedthrough 37 formed by a toothing formed on the periphery of the bushing 9. The nominal diameter of the feed gear 37 is smaller than the nominal diameter of the toothing 28 of the rotating drive gear 7.

  The transmission path of the return movement comprises a return motor pinion 38 which is freely rotatably mounted but axially immobilized in the frame 4 about the intermediate axis 23 and more particularly, in this example, around the column 31, thanks to The return motor pinion 38 meshes with a return driven pinion 41 formed by a toothing formed at the periphery of the bushing 9. The nominal diameter of the driven return pinion 41 is larger than the nominal diameter of the rotating drive gear teeth 7.

  The axial displacement device further comprises selector means whose function is to activate selectively one or other of the two motion transmission paths, advance and respectively return. In the example shown, the selector means selectively couple the tubular shaft with one or the other of the two feed pinions 34 and respectively 38. The tubular shaft 29 extends from the intermediate gear 22 through a bore of the feed motor pinion 34 into an area between the feed motor 34 and return pinion 38.

  Even more particularly, in this example, the selector means comprise a clutch 42 installed axially between the two drive pinions 34 and 38. The clutch 42 is rotatably connected to the tubular shaft 29 while being axially sliding along it . For this, the clutch 42 has a corrugated bore 43 which is traversed by the tubular shaft 29 and interengaged with corresponding grooves 44 formed on the outer face of this shaft.

  On its face turned towards the drive motor pinion 34, the dog clutch 42 has recesses 46 distributed equidistantly along a circle centered on the intermediate axis 23. The recesses 46 are intended to receive bosses 47 arranged of the same way on the face of the drive gear 34 turned towards the clutch 42. In the position shown in Figure 1, the clutch 42 is adjacent to the drive pinion 34, the bosses 47 being engaged in the recesses 46. This achieves the coupling of the feed motor pinion 34 with the tubular shaft 29 and thus, during the rotation of the input shaft 3, a corresponding rotation of the bushing 9 in the same direction as the pin 13 and at a speed which is larger than that of the spindle 13. As a result, the spindle 13 performs an advance movement (arrow A directed downwards in the representation of FIG. 1) while having along the spindle axis 6 a linear speed proportional to its speed e of rotation. Meanwhile, the clutch 42 is free to rotate relative to the return motor pinion 38 which, driven from the sleeve 9, rotates unnecessarily at a speed greater than that of the dog clutch 42.

  On its face turned towards the return motor pinion 38, the dog clutch 42 has recesses 48 distributed at equal distances along a circle centered on the intermediate axis 23. The recesses 48 are intended to receive bosses 49 arranged in the same way on the face of the return motor pinion 38 turned towards the dog clutch 42. In the position shown in Figure 4, the dog clutch 42 is adjacent to the return motor pinion 38, the bosses 49 being engaged in the recesses 48. This achieves the coupling of the return motor pinion 38 with the tubular shaft 29 and thus, during the rotation of the input shaft 3, a corresponding rotation of the sleeve 9 at a speed which is smaller than that of the pin 13 As a result, the spindle 13 performs a return movement (arrow R upwards in the representation of FIG. 4) having along the spindle axis 6 a linear speed proportional to its speed of rotation. Meanwhile, the clutch 42 is free to rotate relative to the driving gear 34 which, driven from the sleeve 9, turns unnecessarily at a lower speed than the clutch 42.

  The selector means further comprise actuating means for selectively positioning the clutch 42 in one or other of its two described positions, and for moving the clutch 42 between these two positions. In the example, the actuating means comprise an actuating member 51 movable in translation along the intermediate axis 23. The clutch 42 is mounted freely rotatable, but axially immobile on the actuating member 51, thanks to in a bearing 52. More particularly, the actuating member 51 is a sleeve slidably mounted on the column 31.

  In the situation of activation of the advance movement transmission path, represented in FIG. 1, the dog clutch 42 is positioned in coupling with the driving gear 34 by the action of a return spring 53 mounted in compression between the frame 4 and the actuating member 51.

  The actuating member 51 is attached to the piston 54 of a pneumatic actuator 56. The piston 54 is movable in a cylinder 57 formed in the frame 4 around the column 31, near its end opposite to the intermediate gear 22. The piston 54 subdivides the cylinder 57 into a working chamber 57a (Figures 3 and 4) through which the transmission member 51, and an atmospheric chamber 57b permanently connected to the atmosphere by vents 57c.

  The transmission member 51 extends between the clutch 42 and the piston 54 by passing through a bore 58 of the driving pinion which is furthest from the intermediate gear 22, that is to say in the example the driving gear of back 38.

  There is therefore one of the motor pinions, the drive gear 34 in the example, which is placed axially between the intermediate gear 22 and the clutch 42, and which is traversed by the motor shaft 29, while the actuating member 51 passes through the other motor pinion, so in the example the return motor pinion 38, placed axially between the dog clutch 42 and the pneumatic actuator 56.

  The pneumatic actuator 56 comprises a compressed air supply duct 59 which is supplied with compressed air from the engine block 1. The duct 59 can communicate with the working chamber 57a by an annular passage formed between the wall external side of the transmission member 51 and an orifice 61 formed in the frame 4 around the transmission member 51. A seal 62 is mounted around the transmission member 51 at its junction with the piston 54 When the piston 54 is held in the position shown in Figure 1 by the return spring 53, the annular passage of compressed air inlet in the chamber 57a is closed by the seal 62 reliably sealed against the periphery of the orifice 61.

  Triggering means are provided for automatically triggering at the end of a machining operation a switch comprising the deactivation of the forward motion transmission path and an initiation of the activation of the return motion transmission path. For this, means are provided to produce a sharp increase in the torque to be transmitted at the end of the machining operation. In the example, these means comprise a collar 63 formed at the end of the pin 13 opposite the tool (in the example shown the collar 63 is located at the top while the tool, not shown, is attached to the lower end of pin 13). The flange 63 is intended to abut against the driving driven gear 7 when the pin 13 reaches along the spindle axis 6 a position corresponding to the end of the drilling operation (situation shown in Figure 3). This stop phenomenon prevents the pin 13 from continuing its advance movement and thus prevents the sleeve 9 from continuing to rotate faster than the pin 13. This results in an increase in the rotational torque in the transmission path of the movement of advanced.

  The triggering means are arranged to be sensitive to this increase in torque to automatically trigger the switchover. This sensitivity is obtained by means limiting the transmissible torque through the transmission path of the advance movement. When the torque to be transmitted by this path increases at the end of the machining operation, there is a disengagement and at the same time an activation of the actuator 56 to move the clutch 42 to its position, shown in FIG. 4, activation of the transmission path of the return movement.

  More particularly, in the example shown, the limiting means of the transmissible torque act between the clutch 42 and the driving gear 34. In the example, the bosses 47 of the driving gear 34 have a hemispherical shape. When the torque to be transmitted exceeds a certain threshold defined by a number of parameters such as the number of bosses 47, the diameter of the circle along which they are distributed, the force of the return spring 53, etc., the bosses 47 operate. as cams (situation shown in Figure 3) which axially push the dog clutch 42 to the return motor pinion 38. At the same time, the transmission member 51 and the piston 54 are pushed axially by compressing the return spring 53. The seal 62 deviates from the periphery of the orifice 61. The compressed air can thus penetrate into the working chamber 57a of the actuator 56. Therefore, the piston 54, subjected to the pressure of the compressed air, moves to the position shown in Figure 4. Via the transmission member 51, the piston 54 carries with it the dog clutch 42 into its coupling position with the return pinion 38. C is now the path of tra nsmission of the return movement that is activated. The rotation of the intermediate gear 22 always continuing in the same direction, the pin 13 makes its return movement symbolized by an arrow R in Figure 4.

  During the return movement, the sleeve 9 rotates in the same direction as the pin 13 but having with respect thereto a difference in rotational speed which is in the opposite direction to that existing between bushing and pin for the movement of advanced. By properly choosing the transmission ratio defined by the return motor pinion 38 and the driven return pinion 41, a suitably fast axial return speed is defined at will without being excessively sharp.

  The device further comprises a valve 64 for venting the working chamber 57a. The side wall of the pin 13 carries a cam 66 positioned to cooperate with a pusher 67 for actuating the valve 64 when the end of the return stroke of the pin 13 is reached. The working chamber 57a is therefore depressurized, allowing the return spring 53 to push the clutch 42 into the position of Figure 1, corresponding to the activation of the transmission path of the advance movement. In addition, the depressurization is transmitted to the engine block 1 via the conduit 59 and causes, for example by deactivating the self-holding of a pneumatic valve not shown, a shutdown of the air motor contained in the block -motor 1. As the return stroke was performed at a reasonable axial speed, the automatic shutdown process just described has time to unfold at a relatively precise point of the return stroke of the spindle, therefore without the pin has time to exceed this predetermined point of its return stroke. A new machining operation is then ready to be initiated for example by simple refilling of the pneumatic motor.

  Of course, the invention is not limited to the example described and shown. There could be two separate sockets, one for the advance movement and the other for the return movement. The motor gear that is closest to the intermediate gear could be the return motor gear.

  With a suitable choice of spindle rotation direction and thread direction, the bushing could turn slower than the spindle for the feed movement and faster than the spindle for the return movement.

  In the present description, and in the accompanying drawings, certain parts are shown schematically. In particular, certain elements, such as the frame, shown as a single piece must or may in practice be made by assembling several pieces to allow or facilitate assembly, according to techniques well known to those skilled in the art.

Claims (14)

  1 - Device for axial displacement of a spindle (13) driven in rotation, in which the spindle is in thread engagement with at least one bushing (9) with internal thread (16) connected to motor means (29; 37, 38, 41) by rotational transmission means, with a first rotational speed difference between the bushing and the spindle for generating an axial feed of the spindle, while an axial return movement of the spindle is generated by imposing between the internal thread (16) and the spindle a second difference in speed in the opposite direction to the first speed difference, characterized in that for the axial return said thread (16) is in drive relation with the motor means for turning in the same meaning as the spindle (13).   2 - Device according to claim 1, characterized in that the transmission means comprises selector means (42, 51, 56) for selectively activating one or the other of two motion transmission paths between the drive means and the socket.   3 - Device according to claim 2, characterized in that the selector means are capable of automatically switching from an activation state of a forward motion transmission path to an activation state of a path of return motion transmission when the spindle (13) reaches an advance end position.   4 - Device according to claim 2 or 3, characterized in that the sleeve carries two driven gears (37, 41) of different diameters which each mesh with a respective motor pinion (34, 38) belonging to a respective one of the two motion transmission paths.   5 - Device according to claim 4, characterized in that the selector means are adapted to selectively couple one or the other of the two drive gears (34, 38) with a common drive member (29). 35   6 - Device according to claim 2 or 3, characterized in that the motor means comprise a common motor member (29), and the two'machines of motion transmission define a different transmission ratio between the common motor member and the sleeve ( 13).   7 - Device according to claim 5 or 6, characterized in that the common motor member (29) through a bore of one of the feed pinion gears (34) and return (38).   8 - Device according to one of claims 5 to 7, characterized in that the selector means comprises a clutch (42) integral in rotation with the common motor member (29).   9 - Device according to one of claims 2 to 8, characterized in that the selector means are of a limited torque transmissible type through the advance movement transmission path (34, 37), and cooperate with an actuator (56) that is activated to toggle the selector means into an activation position of the other motion transmission path (38, 41) when the torque limit is reached.   10 - Device according to claim 8 or 9, characterized in that the clutch (42) is subjected to the action of a spring (53) of return in the activation state of the motion transmission path corresponding to the advance of the spindle (13).   11 - Device according to claim 9 or 10, characterized in that the common motor member (29) is in rotational drive relationship with the pin (13).   12 - Device according to claim 8, characterized in that the common motor member (29) is a shaft secured to a pinion (27) for driving the pin (13) in rotation, in that the two pinions feed motors (34) and respectively return (38) are free in rotation relative to this shaft, and in that the clutch (42) is integral in rotation with this shaft (29) and axially displaceable along it. ci between two positions in each of which it couples one of the drive pinions (34, 38) with the shaft (29).   13 - Device according to claim 12, characterized in that the clutch (42) is mounted axially between the two drive gears (34) and return (38), and the clutch (42) is connected to an actuator (56) by a transmission member (51) passing through a bore (58) of one (38) of the two drive pinions (34, 38), the actuator being located beyond the drive pinion (38).   14 - spindle equipment for rotary machining apparatus, characterized in that it comprises an axial displacement device according to one of claims 1 to 13. - rotary machining apparatus, in particular automatic drill for use industrial, equipped with a tool spindle connected to an axial displacement device according to one of claims 1 to 13 and / or a spindle equipment according to claim 14.