TOOL CHANGING DEVICE

Abstract

A tool changing device is described, which is provided with a male portion constrainable to a handler and a female portion constrainable to a tool to be handled and removably fittable on the male portion. Locking means are provided to lock the female portion on the male portion, and their respective actuator comprising an electric motor. The locking means are selectively movable between a locked position of the female portion and an unlocked position. Differently from conventional solutions, in the device according to the present invention advantageously the activation of the locking means is not assigned to the electric motor, on the contrary the latter has the task of only moving the locking means to the unlocked position; an elastic element is provided instead, which continuously applies a force holding the locking means in the locked position. The electric motor intervenes only to allow the female portion to be separated.

Claims

1. A tool changing device (1) comprising: a main body (2) constrainable to an external handling system; a male portion (4) housed in the main body (2); a female portion (5) constrainable to a tool to be handled and removably fittable on the male portion (4); locking means (11) to lock the female portion (5) on the male portion (4), and an actuator (13, 14) of the locking means (11), wherein the locking means (11) are selectively movable between a locked position, at which they engage the female portion (5) fitted on the male portion (4) and prevent it from detaching from the male portion (4), and an unlocked position at which they do not engage the female portion (5) and allow it detaching from the male portion (4), wherein the actuator (13, 14) of the locking means comprises at least one elastic element (20) and an electric motor, and in that the elastic element (20) continuously applies a force onto the locking means (11) sufficient to move and hold them to the locked position, and the electric motor (15) intervenes when necessary in order to counter such a force and move the locking means (11) to the unlocked position.

2. The device (1) according to claim 1, wherein the locking means (11) comprise a plurality of balls (11) housed in corresponding seats (21) obtained in the male portion (4), and wherein the balls (11) in the locked position protrude at least partially from the respective seats (21) and engage a throat or corresponding niches (12) obtained in the female portion (5), fitted on the male portion (4), therefore realizing an undercut, and in the unlocked position the balls (11) do not engage said throat or said niches (12) of the female portion (5).

3. The device (1) according to claim 2, wherein the male portion (4) has a longitudinal axis (X) and the balls (11) are radially movable with respect to said axis (X).

4. The device (1) according to claim 2, wherein the ball actuator further comprises a thrust element (18) housed at least in part in the male portion (4) and sliding between a forward position, at which it forces the locking means (11) into the locked position, and a rearward position, at which the locking means (11) are in the unlocked position, and wherein the thrust element (18) normally remains in the forward position due to the thrust applied by the elastic element (20) and is moved to the rearward position by the electric motor (15), being constrained therewith, only to allow the detachment of the female portion (5).

5. The device (1) according to claim 4, wherein the male portion (4) is cylindrical or conical and the female portion (5) comprises a hole (6) having a shape complementary with the male portion (4) thus being fittable thereon.

6. The device (1) according to claim 5, wherein the thrust element (18) defines a cylinder-piston coupling with the male portion (4), and wherein the housing seats (21) for the balls (11) are holes obtained through the side wall of the male portion (4), and wherein the thrust element (18) in the respective forward position is contacting the portion of the balls (11) facing the inside of the male portion (4).

7. The device (1) according to claim 6, wherein the outer side surface of the thrust element (18), that is the surface facing the balls (11) and the inner surface of the male portion (4), is tapered (22) at least next to each ball (11) so that to gradually thrust the balls (11) into the respective seats (21) while moving from the rearward position to the forward position, in order to make the balls (11) protrude outside until they reach the locked position.

8. The device (1) according to claim 4, wherein the at least one elastic element (20) is at least one spring interposed between the body (2) of the device and the thrust element (18), said at least one spring (20) being preloaded to continuously apply a thrust to the thrust element (18) to the forward position thereof.

9. The device (1) according to claim 4, wherein the thrust element (18) is operatively coupled with the electric motor (15) by means of an eccentric kinematic system (17).

10. The device (1) according to claim 9, wherein the electric motor (15) is a motor whose shaft (16) is connected with an eccentric cam (17), or a coupling or joint both eccentric, to the thrust element (18), where the axis (Y) of the shaft (16) of the electric motor (15) is orthogonal to the longitudinal axis (X) of the male portion (4).

11. The device (1) according to claim 10, wherein the thrust element (18) comprises at least one groove (23) at which the eccentric cam (17) is in a stable equilibrium position.

12. The device (1) according to claim 1, further comprising a cursor (25) sliding in a respective seat (27) in the body (2), between a proximal position and a distal position with respect to the male portion (4), and wherein the at least one elastic element (20) is at least one spring interposed between the cursor (25) and the thrust element (18), said at least one spring (20) being preloaded to continuously apply a thrust to the thrust element (18) to the forward position thereof.

13. The device (1) according to claim 12, wherein the cursor (25) is operatively coupled with the electric motor (15) by means of an eccentric kinematic system (17).

14. The device (1) according to claim 13, wherein the electric motor (15) is a motor whose shaft (16) is connected with an eccentric cam (17), or a coupling or joint both eccentric, to the cursor (25), where the axis (Y) of the shaft (16) of the electric motor (15) is orthogonal to the longitudinal axis (X) of the male portion (4).

15. The device (1) according to claim 14, wherein the cursor (25) comprises at least one groove (23) at which the eccentric cam (17) is in a stable equilibrium position and the cursor is proximal to the male portion (4).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Further characteristics and advantages of the invention will be more evident by the review of the following specification of a preferred, but not exclusive, embodiment, depicted for illustration purposes only and without limitation, with the aid of the attached drawings, in which:

[0057] FIG. 1 is a perspective view of a first embodiment of the tool changing device according to the present invention, in a configuration with the female portion separated from the male portion;

[0058] FIG. 2 is a perspective view of the device shown in FIG. 1, in a configuration with the female portion coupled to the male portion;

[0059] FIG. 3 is a perspective view of the device shown in FIG. 1, in the same configuration, but equipped with electrical connections;

[0060] FIG. 4 is a perspective view of the device shown in FIG. 1, in a configuration with the female portion coupled to the male portion and equipped with electrical connections;

[0061] FIG. 5 is an exploded view of the device shown in FIG. 1, without the female portion;

[0062] FIG. 6 is a vertical sectional view of the device shown in FIG. 1;

[0063] FIG. 7 is a vertical sectional view of the device shown in FIG. 1;

[0064] FIG. 8 is an exploded view of a second embodiment of the device of the present invention;

[0065] FIG. 9 is a vertical sectional and perspective view of the assembled device shown in FIG. 8, in a first configuration;

[0066] FIG. 10 is a vertical sectional and perspective view of the assembled device shown in FIG. 8, in a second configuration;

[0067] FIG. 11 is a vertical sectional and elevation view of the assembled device shown in FIG. 8, in a first configuration; and

[0068] FIG. 12 is a vertical sectional and perspective view of the assembled device shown in FIG. 8, in a second configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] FIG. 1 is a top perspective view of a device 1 according to the present invention, comprising a box-shaped body 2. On the body 2 a plate 3 is installed and includes a male portion 4 that, in the embodiment shown in the figures, is constituted by a conical portion 4 cantileverly extending from the body 2. The device 1 further comprises a female portion 5 removably couplable to the male portion 4.

[0070] In particular, the female portion 5 has a central hole 6 having a shape complementary to the male portion 4, so that the male portion 4 can be inserted in the female portion 5 with minimum play.

[0071] The body 2, and the male portion 4 therewith, can be both fastened to a manipulator, for example a robotic arm or a numerical control machine, and the female portion 5 can be fastened to a tool or piece to be handled.

[0072] FIG. 2 shows the female portion 5 fitted and locked on the male portion 4. The conical portion 4 is inserted in the hole 6.

[0073] Referring to FIG. 10, connectors for pressurized fluids are depicted.

[0074] FIGS. 3 and 4 correspond to FIGS. 1 and 2, the difference being that the device 1 is shown as provided with electrical connectors 7, 7 and 8, 8 and with a fastening bracket 9 to fasten the body 2 to a manipulator.

[0075] As can be seen in FIGS. 1 and 3, there is a plurality of balls on the conical part 4 of the male portion 4, which are arranged circumferentially at even pitch at the same height. The balls 11 are housed in appropriate seats obtained in the wall of the conical part 4.

[0076] The balls 11 are designed as locking means to lock the female portion 5 on the male portion 4. As a matter of fact the balls 11 are movable, selectively and by command, between an unlocked position radially nearer to the vertical symmetry axis X of the conical part 4, and a locked position radially farther from such axis X.

[0077] At the hole 6 of the female portion 5 a throat is obtained, or better a plurality of niches or grooves 12 in which a ball 11 can be inserted at least in part when it is in the locked position. The niches 12 are tapered so that to define an undercut with the balls 11 and to prevent the female portion 5 from detaching from the male portion 4. FIGS. 2 and 4 just show the female portion 5 locked on the male portion 4, with the balls 11 meshed in the niches 12. The female portion 5 can be separated only by moving the balls 11 to the unlocked position; hereinafter it will be explained how the balls 11 are handled.

[0078] In the example shown in the figures, the device 1 comprises four balls 11 and as many niches 12.

[0079] FIG. 5 is an exploded view of the device 1. With the numeral reference 13 an electric power device is generically depicted, which comprises an electric motor 15 whose shaft 16 extends and rotates on an axis Y orthogonal to the axis X. With the numeral reference 17 a cam eccentrically connected to the shaft 16 of the electric motor 15 is depicted, so that to define a second axis Y parallel to the axis Y.

[0080] With the numeral reference 14 is generically depicted an assembly comprising an element 18 intended to give a thrust to the balls 11 from the inside of the conical portion 4, a supporting plate 19 to support the thrust element 18 and a pack of vertically arranged helical springs 20, i.e. which are parallel to the axis X.

[0081] As can be noted, four through-holes 21 are obtained through the side wall of the conical part 4 of the male portion. The through-holes 21 constitute the housing seat of the balls 11 and are shaped to prevent the balls 11 from excessively protruding to the outside and thus falling; in other words, the balls 11 have to be movable in the holes 21 but anyway they must not come out outwards. In FIG. 7 it is possible to appreciate that the holes 21 are not circular but conical, just to prevent the undesirable fall of the balls 11 outwards.

[0082] The thrust element 18 has a shape substantially complementary to the conical portion 4 in order to slide alternately in inside thereof, as a piston would do in the respective cylinder. The radial displacement of the balls 11 in the holes 21, in the two ways, is just controlled by the alternate vertical movement of the thrust element 18.

[0083] When the thrust element 18 moves to the completely raised position corresponding to the top dead center if referred to the piston in cylinder similarity, the balls 11 are thrust as must as possible into the holes 21 until the locked position is reached, i.e. until a part of the balls 11 protrudes outside of the holes 21 to engage the female portion (not shown in FIG. 5 for simplicity).

[0084] When the thrust element 18 moves to the completely lowered position, i.e. to the inside of the body 2 corresponding to the bottom dead center if referred to the piston in cylinder similarity, the balls 11 are free to come back into the holes 21 until the unlocked position is reached.

[0085] On the outer surface of the thrust element 18 four tapers 22 are obtained acting as guide ramps of the balls 11: when the thrust element 18 moves to the completely raised position, the tapers 22 gradually thrust the balls 11 to the locked position and when the thrust element 18 moves to the completely lowered position, the tapers 22 act as limits preventing the balls from falling inside the male portion 4.

[0086] When the device 1 is assembled the springs 20 are compressed, i.e. preloaded, and continuously apply a thrust onto the supporting plate 19, which in turn tends to hold the thrust element 18 steadily in the raised position. Therefore, the springs 20 operate to hold the balls 11 continuously in the locked position of the female portion 5.

[0087] FIGS. 6 and 7 show this concept in the best way. In particular, in these figures the device 1 is shown with the balls 11 in the locked position, i.e. they are thrust to the limit radially to the outside of the respective holes 21 by the thrust element 18 completely raised by the force the springs 20 apply.

[0088] In order to achieve the detachment of the female portion 5, the electric motor 15 is necessarily activated to rotate the respective shaft 16 by half revolution and, through the cam 17, to thrust downwards the thrust element 18, thus releasing the balls 11 which can partially come back into the holes 21 for the disengagement of the niches 12 visible in FIG. 1. The unlocked position is not shown in the attached figures.

[0089] The cam 17 dwells in a slot 24 obtained in the thrust element 18 and visible in FIGS. 5, 6, and 7. The inner surface of the slot 24 is locally machined to obtain a slight groove depicted with the numeral reference 23. The groove 23, which is just a little hollow, is for defining a stable equilibrium position of the cam 17. Since the cam 17 is assembled eccentrically with respect to the shaft 16 of the electric motor, the presence of the groove 23 is useful for holding the cam 17 in a stable position when the motor is not active.

[0090] The FIG. 8 shows a second embodiment 1 different from the first one 1 in that it comprises a cursor 25 housed in an appropriate seat 27 obtained in the body 2. The cursor 25 slides in the seat 27 in parallel to the axis X, which is the longitudinal axis of the male portion 4. The vertical movements of the cursor 25 in its seat 27 are controlled by the power device 15, also in this example an electric motor, through a cam mechanism 17 equivalent to the above described one.

[0091] The cursor 25 comprises a seat 26 per each spring 20, four in the shown example, which are socket-shaped. In the assembling step the springs 20 are inserted in the seats 26 of the cursor 25 and press onto the thrust element 18 on top.

[0092] FIGS. 9 and 10 aid the comprehension of the operation of the device 1. They are vertical sectional views, respectively on a plane not containing the axis X and on a plane containing the axis X, but anyway orthogonal to the axis Y of the electric motor 15.

[0093] In particular, in FIG. 9 the device 1 is shown in the locked position of the balls 11 and in FIG. 10 it is shown in the unlocked position. In FIG. 9 the thrust element 18 is completely raised since the cam 17 holds the cursor 25 in the maximum height position in the seat 27. Therefore, the cursor 25 is raised to the male portion 4 and the springs 20 hold the thrust element 18 pressed against the male portion 4, in a forward position corresponding to the blocking of the balls 11. In FIG. 10 the thrust element 18 is lowered since the cam 17 holds the cursor 25 in the minimum height position in the seat 27, almost at the bottom. Therefore, the cursor 25 is lowered towards the bottom of the seat 27, and the springs 20, although extended, are not able to hold the thrust element 18 in the forward position and pressed against the male portion 4; on the contrary, the thrust element 18 is in the retracted position, the balls 11 being free to come back into the respective seats 21 to unlock the female portion.

[0094] FIG. 11 clearly shows the device 1 in the locked position, with the balls 11 thrust to the outside by the thrust element 18. In this figure it can be appreciated that the travel D, become available for the cursor 25, is greater than or equal to the length difference between the compressed and extended springs 20, as shown respectively in FIGS. 9 and 10. The travel D must be indeed sufficient to allow the cursor 25 to move the thrust element 18 to a retracted position, although the springs can extend or return to the initial not-preloaded length.

[0095] FIG. 12 shows a vertical section taken on a plane containing the axis Y of the shaft of the electric motor 15. In this figure it can be seen that the cursor 25 is provided with at least one groove 23 at which the cam 17 is in stable equilibrium, corresponding to the device 1 in locked position.