Control unit for controlling the angular end-of-stroke positions of the clamping arm of a locking device of the articulated lever type

Abstract

 A control unit for controlling the angular end-of-stroke positions of the clamping arm of a locking device of the articulated lever type, in which the arm (12) is fastened on a rotatable shaft (16) and is controlled into rotation through a toggle joint unit (22) by the axial sliding of a control rod (20), comprises a support member (5) for supporting a pair of sensors (48, 50) which sense the passing of reference means (32, 34) connected to the rod (20) in order to control its stop when the positions of angular end-of-stroke of the arm (12) are reached. The support member (5) can be fastened to the body (2) of the device at an opening (5a) of the rear zone (3) of the device (1). The sensors (48, 50) are fixed to the support member (5) and the reference means comprise two appendages (32, 34) separated and connected to the rod (20), at least one (34) of which is associated to adjustable fastening means (28, 36, 38, 40) in order to allow to fasten it in one of a plurality of positions along the rod (20).

Description

[0001] The present invention refers to locking devices of the articulated lever type provided with a clamping arm which can swing in order to allow to clamp workpieces with respect to the body of the device.

[0002] More specifically, the invention relates to a control unit for controlling the angular end-of-stroke positions of the clamping arm of such a device, of the type defined in the preamble of appended claim 1.

[0003] Such a control unit is known from EP-803 331, and it comprises a support member for supporting a pair of sensors, typically micro-switches for example of the inductive or pneumatic type, which are removably associated to the support member in order to allow the adjustment of their mutual distance, which sensors are intended to sense the passing close to them of an appendage extending from a the rod which controls the movement of the arm. The angular end-of-stroke positions of the clamping arm can be adjusted by changing the respective position of the sensors on the support member. The support member to which the sensors are associated, can be inserted in a long and narrow slot extending longitudinally at the rear zone of the body of the device, in order to close sealingly the slot with the aim to prevent penetration inside the body of extraneous elements coming from the external environment.

[0004] This solution has however some disadvantages. In fact, it is necessary to remove the support member from the body of the device and to move manually the sensors in order to adjust the respective position of the sensors. This operation involves a high risk both to damage the sensors, which are very delicate and expensive, and to interfere with the wirings associated to them, and therefore to cause a malfunction of the sensors. On the other hand, the removal of the support member from its seat exposes the inside of the device to a risk of contamination by the external environment, and the consecutive steps of removal and reinsertion of the support member in its seat may reduce the effectiveness of the sealing of the member with respect to the edges of the slot.

[0005] In order to overcome these disadvantages, the subject of the invention is a control unit having the features indicated in the appended claims.

[0006] In particular, the control unit of the invention, in addition to have a simple and reliable structure, allows to adjust the end-of-stroke positions of the clamping arm without any need to remove the sensor support member, so that the sensors are not exposed to any risk of damaging and no effect is produced on the sealing exerted by the support member with respect to the edges of the opening of the body in which it is inserted, which makes therefore the adjusting operation of the end-of-stroke of the swing of the arm at the same time much faster and simple. Moreover, the opening in correspondence of which the support member is arranged does not have an elongated shape such as to affect a large zone of a face of the body of the device, but can have a more compact shape the extension of which is considerably smaller than that of the entire support member, so that the influence of the opening on the design requirements of the body of the device is reduced.

[0007] Further characteristics and advantages of the invention will become more clearly evident from the reading of the detailed description which follows, given purely by way of a non limiting example and referred to the attached drawings, in which:

figure 1 is a side elevational view of a locking device provided with a control unit according to the invention,

figure 2 is a side elevational view of the device of the figure 1 in the open condition,

figure 3 is an enlarged perspective view of a portion of the device of figure 2,

figure 4 is a side elevational view similar to figure 2, in which the clamping arm is in the closing position of the device,

figure 5 is an enlarged view similar to figure 4, pointing out a step of the insertion of the support member of the control unit into the body of the device,

figure 6 is an enlarged perspective view of the support member indicated by arrow VI in figure 5,

figure 7 is an enlarged perspective and exploded view of a portion of the control unit indicated by arrow VII in figure 5,

figure 8 is a view similar to figure 4 showing a different adjustment condition of the control unit,

figure 9 is a partial perspective and enlarged view of the device of figure 8 from the direction indicated by arrow IX, and

figure 10 is a rear elevational view sectioned along line X-X of figure 9, in which the body of the device has been removed.

[0008] With initial reference to figures 1 to 7, a locking device of the articulated lever type, which can be used for clamping workpieces, is indicated 1 as a whole. A generally fork shaped clamping arm 12 is associated to the body 2 of device 1 and is fastened to the square sectioned ends of a shaft 16 by means of U-shaped locking members 14. The arm 12 can swing between a preset opening position (one of which is shown by solid lines in figure 1) and a closing position (shown by dashed lines in the same figure).

[0009] The shaft 16 is provided centrally by a radial control appendage 18 (figure 3) having the function of a crank, which is connected by means of an articulation pin to a pair of connecting rods 23 which are in turn connected to the end of a control rod 20 slidably guided inside the body 2, by means of another articulation pin engaging a hole 20a. The articulated joint serving to connect the shaft 16 with the rod 20, which comprises the pair of connecting the rods 23 and the control appendage 18, forms an articulated toggle joint of the device 1, of a type per se known and indicated as a whole by the reference numeral 22.

[0010] The sliding of the rod 20 is usually controlled by automatic drive means which, in the most common case, comprise a fluid-driven double acting cylinder 4, typically pneumatic, which is fixed at the bottom of the body 2.

[0011] Inside the body 2, which is formed by two symmetrical half-shells coupled to each other, a coaxial sleeve 28 is slidably mounted outside the rod 20. A pin-shaped appendage 32 extends from the sleeve 28 towards a rear wall 3 of the body 2, transversely to the axis of the sleeve 28. Preferably, the pin 32 is removably mounted on the sleeve 28, for example by means of a threaded connection, allowing therefore to modify the extension of its portion projecting from the sleeve itself.

[0012] On a side of the sleeve 28 an axial through slit 30 is provided, in which another appendage 34 connected to the rod 20 and also having the shape of a pin, is guided. The pin 34, which is parallel to the pin 32, is preferably mounted radially and removably on the rod 20, for example by means of a threaded connection, in order to allow to change its extension with respect to the rod 20.

[0013] The sleeve 28 is provided with fastening means adapted to fasten it selectively in a plurality of positions axially spaced along the rod 20. These fastening means preferably comprise a pair of threaded through holes 36, transverse to the axis of the sleeve 28 and formed at diametrically opposite zones with respect to the rod 20. A locking dowel screw 38, having an end provided with a hexagonal hollow seat 38a, can be engaged in each one of the holes 36. The seat 38a is intended to be engaged by a corresponding control wrench (not shown in the figures) which can be inserted through an opening 52 of each half-shell forming the body 2, in order to selectively fasten the sleeve 28 in one of a plurality of axial positions along the rod 20, for the purposes which will be explained in greater detail in the following. Conveniently, the openings 52 are closed by means of easy removable plugs (not shown), for example of plastic material, which can be inserted by pressure.

[0014] Respective axial rows of seats are formed on diametrically opposite sides of the rod 20, each seat being constituted by a blind hole 40 which can be engaged by the end of the dowel screw 38 opposite to its hexagonal seat 38a, the holes 40 on a side of the rod 20 being axially offset with respect to the holes 40 of the opposite side. In particular, the consecutive holes 40 formed both on a side and on the opposite side of the rod 20 are axially spaced of a constant pitch, for example corresponding to a rotation of 10° of the clamping arm 12.

[0015] A support member, indicated as a whole with the reference numeral 5, is associated to the body 2 of the device 1. The support member supports a pair of fixed sensors 48, 50, typically consisting of microswitches for example of the inductive, magnetic or pneumatic type, which are adapted to sense the passage in their proximity of the pins 32 and 34 as a result of the sliding of the rod 20 and the sleeve 28, in order to control the stopping of the axial sliding of the rod 20 when it reaches the end-of-stroke positions corresponding to the preset angular end-of-stroke positions of the arm 12. The member 5 can be fixed to the body 2 at a rectangular opening 5a formed in a rear wall 3 of the body 2 of the device 1.

[0016] In particular, the sensors 48 and 50 are rigidly connected to a substantially L-shaped support post 46. The end of the less extended branch of the post 46 is fixed to a cover plate 42 having a shape corresponding to that of the opening 5a and intended to close sealingly such an opening in the assembled condition of the member 5. The plate 42 supports a case 42a containing the electronic control elements of the sensors 48 and 50 and, usually, a series of external LEDs for the visual signaling of their operative condition. An electrical connector extends from the case 42a, provided with wirings 7 to transmit pulses for controlling the operation of the cylinder 4 as a result of the operative condition of the sensors 48, 50. The plate is usually provided with holes 44 adapted to be engaged by locking screws (not shown) in order to allow the fixing of the plate 42 to the body 2.

[0017] The sensors 48 and 50 are arranged on the post 46 according to positions outset sideways to each other, so that they face the directions of the axial movement of the free ends of the respective pins 32 and 36 following to the sliding of the rod 20 inside the body 2.

[0018] Preferably, the extension of the cover plate 42 in the axial direction of the rod 20 is considerably smaller of the extension of the entire support member 5, and therefore the opening 5a of the body 2 can be kept small and not much extended axially so as to affect only a small portion of the rear wall 3 of the body 2.

[0019] In order to couple the support member 5 together with the respective sensors 48 and 50 to the body 2, as shown in figure 5, the end of the post 46 opposite to the plate 42 is initially introduced in the opening 5a and, by applying a small rotation to the member 5, the post 46 is brought into a position adjacent to the wall 3 which separates it from the external environment, and the plate 42 is simultaneously arranged at the edge of the opening 5a so as to close it sealingly.

[0020] In the operation of equipment 1, when the arm 12 is in the open position (figures 2 and 3) the pin 34 projecting from the sleeve 28 faces the sensor 50. In this condition, the sensor 50 generates a control signal for stopping and/or switching the operation of the cylinder 4. When the cylinder 4 starts again its operation so as to control the sliding of the rod 20 in order to cause the closing of the arm 12, the pin 32 reaches a position facing the sensor 48 as a result of this sliding, in which the sensor 48 sense the passage of the pin 32 and generates a new signal for stopping and/or switching the operation of the cylinder 4.

[0021] When it is necessary to modify the excursion of the angular swing of the arm 12, for example in order to adapt the device 1 to a different operative condition, it is sufficient to remove the locking dowel screw 38 from the sleeve 20, acting through one of the openings 52 of the body 2, to bring the arm 12 in the new opening position and to cause the sleeve 28 to slide along the rod 20 until it abuts against the bottom of the body 2 at the side of the cylinder 4. In this position, the transverse holes 36 of the sleeve 28 are aligned with the openings 52 of the half-shells of the body 2. It is therefore possible to introduce the locking dowel screw 38 in the hole 36 which is aligned also with one of the holes 40 of the rod 20, and to act so as to rotate it by means of the control wrench until the sleeve 28 is fastened to the rod 20 in the newly reached position. In this new adjustment condition, as more clearly shown in figures 8 to 10, the position of the pin 32 will remain unchanged, therefore allowing to control through the sensor 48 the attainment of the closing position of the arm 12, as before, while the position of the pin 34 which has been changed with respect to the rod 20 will allow to sense the new opening position of the arm 12 when the pin 34 will pass close to the sensor 50.

Claims

1. Control unit for controlling the angular end-of-stroke positions of the clamping arm of a locking device of the articulated lever type, the arm (12) being fastened on a shaft (16) rotatably mounted about an axis of rotation and being controlled into rotation through an articulated toggle joint unit (22) as a result of the axial sliding of a control rod (20) with respect to the body (2) of the device (1), the unit comprising a member (5) for supporting a pair of sensors (48, 50) adapted to sense the passage close to them of reference means (32, 34) connected to the control rod (20), with the aim of controlling the stop of the axial sliding of the rod (20) in its directions of sliding when it reaches respective preset angular end-of-stroke positions of the arm (12), the support member (5) being adapted to be fixed to the body (2) of the device at an opening (5a) formed in the rear zone (3) of the device (1),
   characterized in that said sensors (48, 50) are rigidly connected to the support member (5) and in that the reference means comprise a pair of appendages (32, 34) which are axially separated and are connected to the rod (20), at least (34) one of the appendages (32, 34) being associated to adjustable fastening means (28, 36, 38, 40) in order to allow to fasten it in one of a plurality of positions along the control rod (20).

2. Unit according to claim 1, characterized in that said sensors (48, 50) are arranged according to positions offset sideways to each other and in that each of said appendages (32, 36) is arranged in such a manner to move along a direction of movement facing the respective sensor (48, 50) as a result of the sliding of the rod (20).

3. Unit according to claim 1 or 2, characterized in that said appendages are removable pins (32, 34) associated to the rod (20), each of which has a free end directed in the direction of the respective sensor (48, 50).

4. Unit according to claim 2 or 3, characterized in that said pair of appendages comprises a first appendage (32) extending from the rod (20) and a second appendage (34) extending from a sleeve (28), which sleeve (28) is arranged coaxially outside the rod (20) and slidably with respect to it, has an axial slit (30) adapted to be crossed by the first appendage (32) and comprises fastening means (36, 38) for selectively fastening it in one of a plurality of axial positions with respect to the rod (20).

5. Unit according to claim 4, characterized in that said fastening means for fastening the sleeve include a counter member (38) which can be moved transverse to the rod (20) and which has an end intended to engage selectively one of a plurality of seats (40) formed in the rod (20).

6. Unit according to claim 5, characterized in that said fastening means for fastening the sleeve (28) comprise a counter member (38) which can be arranged at opposite sides of the sleeve (28) with respect to the rod (20), and in that the rod (20) has respective series of seats (40) at positions corresponding to those in which the counter member (38) may be arranged on the sleeve (28), each seat (40) being selectively engageable by an end of the counter member (38), the seats (40) of each of said series of seats (40) being axially offset along the rod (20) with respect to the seats (40) the other series of seats (40).

7. Unit according to claim 5 or 6, characterized in that the counter member (38) can be controlled from the outside of the body (2) of the device (1) through a respective side opening (52) of the body (2).

8. Unit according to claim 7, characterized in that the counter member is a locking dowel screw (38) adapted to engage a corresponding through threaded hole (36) formed transversely in the sleeve (28) and having an hexagonal hollow seat (38a) at its end opposite to the rod (20), for the engagement by a corresponding control wrench which can be inserted through a respective slit (52) of the body (2).

9. Unit according anyone of claims 1 to 8,
characterized in that the support member (5) for supporting the sensors (48, 50) includes a cover plate (42) intended to close sealingly said opening (5a) formed in the rear zone (3) of the body (2) of the device (1), and in that a post (46) for supporting the sensors (48, 50) extends from the cover plate (42).

10. Unit according to claim 9, characterized in that the support post (46) is substantially L-shaped.

11. Unit according to claim 9 or 10, characterized in that the extension of the cover plate (42) in the axial direction of the rod (20) is considerably smaller than the extension of the support member (5), and in that the connection of the support member (5) with the body (2) of the device (1) comprises a first step in which the post (46) is inserted into the opening (5a) of the rear zone (3) of the body (2) of the device (1), and a second step in which the support member (5) is subject to a rotation until the cover plate (42) reaches a position in which it sealingly closes the opening (5a).

Drawing