Locking device for locking tools in a press brake

Abstract

A locking device for locking tools in a press brake includes a first jaw (2) and a second jaw (3), movable towards and away from each other, and at least one safety hook (4) interposed there between provided with a retaining tooth (41) adapted to be inserted into a groove (52) defined in the shank (51) of a tool (5), wherein on an inner side (35) of the second jaw (3) facing the first jaw (2) there is provided at least one thrust surface (36) adapted to cooperate with, while resting slidingly against, at least one corresponding rest surface (43) on an outer side (42) of the safety hook, the thrust surface (36) and the rest surface (43) lying substantially parallel along a thrust plane (P) sloping in the opposite direction to the first jaw (2) by an angle (α) of between 30° and 60° with respect to a vertical plane.

Claims

1. A locking device for locking tools in a press brake, comprising: a first jaw and a second jaw, movable towards and away from each other, and at least one safety hook interposed between said first jaw and said second jaw provided with a retaining tooth inserted into a groove defined in a shank of a tool, wherein on an inner side of said second jaw facing the first jaw there are a plurality of thrust surfaces cooperating with, while resting slidingly against, a same number of corresponding rest surfaces on an outer side of the safety hook, said thrust surfaces and said rest surfaces lying substantially parallel along corresponding thrust planes sloping in a direction to the first jaw by an angle (α) of between 30° and 60° with respect to a vertical plane, said thrust planes being parallel to and staggered from one another along a substantially vertical direction.

2. The locking device according to claim 1, wherein said angle (α) is between 45° and 50°.

3. The locking device according to claim 1, wherein said safety hook has a guide element that guides the safety hook along said thrust plane.

4. The locking device according to claim 3, wherein said guide element comprises a slider sliding in a seat on an inner side of the second jaw.

5. The locking device according to claim 4, wherein the slider has at least a first guide surface sliding on a corresponding guide surface on the second jaw, said guide surface also being a thrust surface of the safety hook.

6. The locking device according to claim 1, wherein said thrust surfaces and said rest surfaces are between two and six in number.

7. The locking device according to claim 1, wherein the safety hook has a cantilever portion, projecting towards the first jaw, provided with a lower face sloping from a bottom of the safety hook upwards in a direction of the first jaw by an angle (β) of between 80° and 110° with respect to a vertical abutment plane located on an inner side of the safety hook.

8. The locking device according to claim 1, wherein in the second jaw there is at least one seat into which is inserted a through positioning pin, and one end of the through positioning pin is fixed to the safety hook.

9. The locking device according to claim 1, further comprising retaining means that act on the safety hook to slow downward movement of the safety hook away from the second jaw.

10. The locking device according to claim 9, wherein said retaining means comprise an elastic means housed in a seat in the second jaw adapted to exert a force along a direction parallel to the thrust plane.

11. The locking device according to claim 10, wherein said elastic means rest on a head of a pin integral with the safety hook and housed at least partly in the seat.

12. The locking device according to claim 1, further comprising guide pins housed in through holes in the second jaw adapted to guide said second jaw towards or away from the first jaw, said through holes having a larger dimension with respect to the guide pins so that the second jaw can sustain vertical movements with respect to the first jaw.

13. The locking device according to claim 12, wherein at least one elastic means housed in the second jaw acts on the guide pins to maintain said second jaw in a raised position in which the guide pins contact lower edges of the respective holes.

14. The locking device according to claim 13, wherein said elastic means comprise a spring inserted in a seat that intercepts the hole of the guide pin, one end of the spring contacting the guide pin.

15. A locking device for locking tools in a press brake, comprising: a first jaw and a second jaw, movable towards and away from each other, and at least one safety hook interposed between said first jaw and said second jaw, the at least one safety hook having a retaining tooth inserted into a groove in a shank of a tool, wherein on an inner side of said second jaw facing the first jaw there is at least one thrust surface adapted to cooperate with, while resting slidingly against, at least one corresponding rest surface obtained on an outer side of the safety hook, said thrust surface and said rest surface lying substantially parallel along a thrust plane sloping in a direction to the first jaw by an angle (α) of between 45° and 50° with respect to a vertical plane.

16. A locking device for locking tools in a press brake, comprising: a first jaw and a second jaw, movable towards and away from each other, and at least one safety hook interposed between said first jaw and said second jaw, the at least one safety hook having a retaining tooth inserted into a groove in a shank of a tool, wherein on an inner side of said second jaw facing the first jaw there is at least one thrust surface adapted to cooperate with, while resting slidingly against, at least one corresponding rest surface obtained on an outer side of the safety hook, said thrust surface and said rest surface lying substantially parallel along a thrust plane sloping in a direction to the first jaw by an angle (α) of between 30° and 60° with respect to a vertical plane, and the at least one safety hook has a guide element that guides the safety hook along said thrust plane.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Further characteristics and advantages of the present invention will become more apparent from the indicative, and therefore non-limiting, description of an example of a preferred but not exclusive embodiment of a locking device for locking tools in a press brake, as illustrated in the accompanying drawings, in which:

(2) FIG. 1 is a side view of a locking device according to the invention;

(3) FIG. 2 is a partly sectional front view of the locking device according to the invention;

(4) FIG. 3 is a sectional side view, along a vertical plane A-A, of the locking device according to the invention;

(5) FIG. 4 is a sectional side view, along a vertical plane B-B, of the locking device according to the invention;

(6) FIG. 5 is a sectional side view, along a vertical plane C-C, of the locking device according to the invention;

(7) FIG. 6 is a sectional side view, along a vertical plane D-D, of the locking device according to the invention;

(8) FIG. 7a is a sectional side view of the second jaw of the device according to the invention;

(9) FIG. 7b is a sectional side view of the safety hook of the device according to the invention;

(10) FIGS. 8a to 8d are respectively side views showing the steps of insertion of a tool into locking device;

(11) FIGS. 9a and 9b are respectively side views showing the steps of clamping of the jaws of the locking device;

(12) FIG. 10 is a lateral view that shows the step of release of the jaws of the locking device;

(13) FIGS. 11a to 11d are respectively side views showing the steps of extraction of a tool from the locking device;

(14) FIG. 12 is a side view showing a shank of a tool of known type.

DETAILED DESCRIPTION OF THE INVENTION

(15) With reference to the accompanying figures, the number 1 indicates a locking device for locking tools in a press brake, as a whole.

(16) This device can be used to constrain a tool, indicated with 5, produced with a monolithic body or divided into a plurality of sub-multiples.

(17) A press brake or bending press, not shown in the accompanying figures, generally comprises a bottom bed defining a fixed plane on which to rest the sheet metal and carrying a bending die according to the profile of which the sheet metal is to be bent.

(18) An upper beam is supported so that it can move towards and away from the bed, along a substantially vertical plane. Movement is generated by hydraulic, mechanical or electrical actuator means, which provide the necessary force for the deformation operation. The beam carries integral therewith a bending tool adapted to cooperate with the die to give the sheet the desired shape. The locking device 1 can be associated with a beam of a press brake to lock one or more tools 5 with respect thereto.

(19) In the present description, with reference to the locking device, the terms vertical and horizontal shall be used to refer to its position in use in a press brake. In particular, the term vertical indicates a direction parallel to the direction in which the upper crossbeam of the press slides.

(20) The tool 5, in conformity with the prior art, consists of a body whose lower end is structured to cooperate with the resting surface of the die and an upper portion that defines a shank 51 of the locking device 1.

(21) On at least one face of the shank there is obtained a groove 52 having a substantially C-shaped cross section, which enables the tool 5 to be maintained suspended when the locking device is released for replacement operations, and said tool 5 to be taken to the correct operating position when the locking device is clamped.

(22) The device 1 comprises a first jaw 2 and a second jaw 3 movable towards and away from each other and at least one safety hook 4 interposed between said first and said second jaw.

(23) Said safety hook, is provided at the base with a retaining tooth 41 structured to be housed in the groove 52 of the shank 51 and adapted to maintain the tool suspended when the locking device is released, for example at the end of the insertion step and at the start of the removal step thereof.

(24) In a preferred embodiment, the locking device 1 is provided with one or more safety hooks 4 arranged longitudinally side by side, i.e. along the direction of extension of the beam.

(25) The first jaw comprises a body 20 in turn associable with the upper beam of the press by means of a shank 21 placed at the top. Said body is provided with a sliding surface 22 facing the second jaw 3 that extends on a plane substantially vertical and parallel to the longitudinal extension of the upper beam. On said sliding surface 22 there can slide the face 53 of the shank 51 opposite the face 56 on which the groove 52 is obtained. At the base of said sliding surface 22 there is defined a contact surface 23 that extends in a direction substantially orthogonal thereto and adapted to contact a step 54 that extends orthogonally from the face 53 of the shank 51.

(26) The second jaw 3 is associated slidingly with the first jaw 2, to move towards and away from it, through actuator means 6 of known type.

(27) In a preferred embodiment, said actuator means comprise at least one control pin 61. Said control pin 61 passes through a hole 31 obtained in the second jaw 3 and is screwed, with the possibility of a limited partial screwing or unscrewing, in a threaded hole 26 in the first jaw 2. The control pin 61 also comprises a head 62, housed in a seat 33 obtained on the outer face of the second jaw 3, which prevents the pin 61 both from slipping out of this latter and from exerting thrust on said jaw by means of a contact surface in the seat 33.

(28) By acting with a specific tool on the control pin 61 it is possible to translate the second jaw 3 towards the first jaw 2 to clamp the tool 5 in the locking device or, vice versa, to move it away from the first to release and extract the tool.

(29) Guide pins 63, housed in through holes 64 obtained in the first jaw, act as guide for sliding of the second jaw 3 towards or away from the first jaw 2.

(30) To facilitate movement of the jaws 2, 3 away from each other, said guide pins are preferably associated with springs or the like interposed between the inner faces of said jaws.

(31) In an alternative variant, not illustrated, said manual actuator means can be replaced with pneumatic or hydraulic actuators well known in the art.

(32) In a preferred variant of the invention, the hole 31 and/or the holes 64 have a larger dimension with respect to the respective control pin 61 and guide pins 63.

(33) Said holes 31 and/or 64 can have a circular or slotted profile. In this way the second jaw 3 can undergo slight vertical movements with respect to the first jaw 2. Preferably, at least one elastic means 65 is housed in the second jaw 3 to maintain it raised so that the guide pins 63 remain in contact with the lower edge of the respective holes 64.

(34) In a preferred embodiment, in the second jaw 3 there is obtained at least one seat 66 into which a spring 65 is inserted. The seat 66 extends until intercepting the hole 64 so that one end of the spring 65 contacts the guide pin 63. The opposite end 66a of the seat 66 is closed by a cover 67 that acts as abutment for the spring 65. Preferably, the cover 67 comprises a threaded element that can be screwed or unscrewed in the seat 66 to compress the spring 65 to a greater or lesser extent and thus vary its preload.

(35) When the jaws 2, 3 are clamped by means of the control pin 61, the second jaw 3 is able to adjust vertically so as to offset any differences in the dimension of the height of the shank 51 of the tool 5 with respect to the nominal value. The springs 65 that act on the guide pins 61 prevent excessive clearance of the second jaw 3 with respect to the guide pins 63 during the clamping step.

(36) The second jaw 3 comprises a body 30 with a lower appendage 34 adapted to cooperate with the safety hook 4 during the various operating steps of the locking device.

(37) According to a preferred embodiment, on an inner side 35 of the appendage 34 there is obtained at least one thrust surface 36 that operates resting slidingly on a corresponding rest surface 43 obtained on an outer side 42 of the safety hook 4.

(38) In practice, said surfaces 36, 43 slide substantially parallel along a thrust plane P, sloping in the opposite direction to the first jaw 2, i.e. viewed from the front as in the accompanying figures, from the bottom upwards and from right to left, by an angle of between 30° and 60°.

(39) In a preferred embodiment said thrust plane P is sloping by an angle of between 45° and 50°.

(40) When the second jaw 3 is clamped towards the first jaw 2, the rest surface 43 thus slides on the thrust surface 36 causing translation of the safety hook 4, which, as will be clearer below, enables the tool 5 to rest thereagainst.

(41) In a preferred embodiment, on the appendage 34 of the second jaw 3 there are obtained a plurality of parallel thrust surfaces 36 that lie on the same number of thrust planes P. Likewise, on the outer side 42 of the safety hook 4 there are obtained a same number of rest surfaces 43 each of which resting slidingly on a thrust surface 36.

(42) This enables the total sliding and thrust surface between the second jaw 3 and the safety hook 4 to be increased, regardless of a very limited horizontal extension of the safety hook 4, which has a positive influence on the horizontal dimensions of the locking device 1.

(43) Moreover, this configuration of the safety hook 4 is effective to also substantially reduce the longitudinal extension, i.e. the width, if observed from the front, with the advantage of ensuring greater safety also when changing tools divided into several parts or sub-multiples of small dimensions, as will be clearer below.

(44) A larger total thrust surface also enables a reduction in the contact pressure, reducing wear on the surfaces and the force to be applied to the actuator means 6 to clamp the jaws.

(45) Finally, the staggered position of the rest surfaces 43 enables the thrust to be distributed more evenly along the vertical extension of safety hook 4.

(46) Advantageously, the thrust surfaces 36 and rest surfaces 43 can be between two and six in number.

(47) In the preferred variant of embodiment, the number of thrust surfaces 36 and of rest surfaces 43 is respectively three.

(48) The travel of the safety hook 4 on the second jaw 3 is limited by at least one stop surface 79 preferably obtained on the inner side of said second jaw. Said stop surface 79 is for example a transverse surface with one or more thrust surfaces 36.

(49) This stop surface 79 is contacted with the safety hook 4 in the end of travel position. For this purpose, the safety hook 4, on the outer side 42, can have a stop surface 70 parallel to that of the second jaw.

(50) Moreover, or in alternative, on the cantilever portion there can be provided a stop tooth 40 adapted to contact a face 24 of the first jaw 2 facing the cantilever portion 45 when the safety hook is in the position of maximum height.

(51) The safety hook 4 is also provided with a guide element 46 adapted to guide the safety hook in the translation along the thrust plane P. More in detail, the guide element 46 prevents undesirable rotations of the insert both during the steps of clamping and release of the jaws, and during removal of the tool. The guide element 46, in practice, maintains the thrust surfaces 36 and the rest surfaces 43 substantially in contact.

(52) In a preferred variant the guide element 46 comprises at least one slider 46a sliding in a seat 71 obtained in the second jaw 3. More in detail, the seat 71 is obtained on the inner side 35 of the second jaw. The slider 46a is preferably produced in once piece with the safety hook 4.

(53) In a possible embodiment, the slider 46a has at least one first guide surface 46b adapted to slide resting on a corresponding guide surface 73 obtained on the second jaw 3. Preferably, the slider 46a is provided with a second guide surface 46c adapted to slide resting on a corresponding guide surface 74 obtained on the second jaw 3.

(54) Advantageously, the guide surface 73 of the second jaw 3 also acts as thrust surface 36, just as the guide surface 46b of the slider acts as rest surface.

(55) The two guide surfaces 46b, 46c of the slider 46 are parallel with each other and parallel to the thrust plane P. The height H of the slider 46a is substantially the same as the distance between the first and the second guide surface 46b, 46c. In practice, when the slider is housed in the seat 71 the safety hook 4 can only translate along a direction parallel to the thrust plane P.

(56) The guide element 46 can have a width (observing the device from the front) the same as, less than or even greater than the width of the safety hook 4.

(57) From the base of the second jaw 3, and specifically of the appendage 34, there extends, towards the first jaw 2, a stop foot 37 on which the safety hook 4 can rest when the jaws 2, 3 are released, and which defines a lower stop position of this safety hook 4.

(58) At the top the safety hook 4 is provided with a cantilever portion 45 that projects towards the first jaw 2 and that is above the top 57 of the shank 51.

(59) The cantilever portion 45 has a lower face 45a sloping towards the first jaw 2, i.e. viewed from the front as in the accompany figures, from the bottom upwards and from left to right, by an angle β of between 80° and 110° with respect to the vertical abutment plane 49 of the safety hook 4.

(60) An angle that has been found to be optimal is of around 90°.

(61) The retaining tooth 41 of the safety hook 4 defines an engaging surface 46 against which there rests a face 55 of the groove 52 obtained in the shank 51.

(62) The aforesaid engaging surface 46 extends in a substantially orthogonal direction with respect to a vertical abutment plane 49 that is located on an inner side 44 of the safety hook 4.

(63) In the upper part, the vertical abutment plane 49 has a flare 49b that reduces the surface of the abutment plane that contacts the shank 51. This enables the point in which the clamping force is applied on the shank 51 to be translated downwards, thereby limiting the possibility of the tool 5 undergoing slight rotations when subject to strain during us.

(64) On an opposite side with respect to the engaging surface 46, the retaining tooth has a chamfer 48 that acts as a guide to facilitate insertion of the shank 51 between the first jaw 2 and the safety hook 4.

(65) In a preferred embodiment, in the appendage 34 of the second jaw 3 there is obtained at least one seat 38, preferably in the shape of a through slot extending vertically, inserted into which is a through positioning pin 39, the end of which is fixed to the safety hook 4. The function of said positioning pin 39 is to constrain the safety hook 4 to a translation along a longitudinal direction, i.e. parallel to the extension of the crossbeam.

(66) In a variant of the invention, the locking device is also provided with retaining means 75 that act on the safety hook 4 to slow its downward movement in the direction parallel to the thrust plane P.

(67) In practice, the retaining means 75 apply to the safety hook a force with a component opposing the force of gravity that normally causes the safety hook 4 to descend towards the stop foot 37.

(68) Advantageously, as will be better illustrated below, these retaining means facilitate removal of the tool 5 from the jaws 2, 3 when these are released.

(69) According to a preferred embodiment, the retaining means comprise an elastic means 76 that exerts its force along a direction parallel to the thrust plane P. Said elastic means is, for example, a coil spring or the like. More in detail, the coil spring 76 can be housed in a seat 77 obtained in the second jaw 3.

(70) A pin 78 constrained to the safety hook has a portion 78a housed inside the seat 77. The spring 76 rests on a head 78b of the pin 78 that transmits the elastic force to the safety hook 4. In the variant illustrated, the spring 76 is arranged around the pin 78 between the head 78b and a contact surface 77a of the seat 77.

(71) Operation of the locking device of the invention is as follows.

(72) The devices enables insertion and removal of the tool 5 with a vertical movement and removal thereof with a combined rotation and translation movement.

(73) FIGS. 8a-8d represent in sequence the steps of insertion of the shank 51 of a tool 5 between the two jaws of the locking device 1.

(74) The first jaw 2 and the second jaw are maintained space apart by the elastic means that, when the control pin 61 is rotated in the release condition, cause the second jaw 3 to move away from the first jaw 2.

(75) The tool 5 is inserted manually by exerting thereon a vertical thrust from the bottom upwards as indicated by the arrow in FIG. 8a.

(76) The top 57 of the shank, contacting the chamfer 48 of the retaining tooth 41, pushes the safety hook 4 that, guided by the guide element 46, slides upwards parallel to the thrust plane P resting on the thrust surfaces 36 of the second jaw 3.

(77) During translation the retaining tooth 41 moves back towards the second jaw 3 until the top 57 of the shank moves beyond the chamfer 48 of the retaining tooth 41.

(78) After moving beyond this point the surface 56 of the shank slides upwards in contact with the retaining tooth 41 (FIG. 8b).

(79) Once the face 55 of the groove 52 is at a greater height than the engaging surface 46, the weight of the safety hook 4 causes this to descend slightly until the lower face 45a of the cantilever portion 45 contacts the top 57 of the shank. During descent the safety hook 4 also translates towards the first jaw 2 causing the retaining tooth 41 to enter the groove 52. (FIG. 8c)

(80) At this point if the tool is released it will descend slightly until the face 55 of the groove 52 is resting on the engaging surface 46 of the retaining tooth 41, as can be seen in FIG. 8d. In this condition the tool 5 is maintained stably in the locking device. In fact, the weight of the tool 5 causes the safety hook 4 to be drawn downwards and, at the same time, by virtue of the slope of the thrust surfaces 36, towards the face 56 of the shank 51.

(81) FIGS. 9a and 9b represent in sequence the steps of clamping of the two jaws.

(82) The control pin 61 is rotated in the screwing direction in the first jaw 2 so as to push, along a substantially horizontal direction, the second jaw 3 towards the first jaw 2. Simultaneously the thrust surfaces 36 of the second jaw press on the rest surfaces 43 of the safety hook 4 that, due to the slope of the thrust plane P on which the aforesaid surfaces lie, is pushed simultaneously upwards and towards the first jaw 2, drawing the tool 5 (FIG. 9a). It should be noted that in this condition the safety hook 4 cannot rotate as it is maintained by the guide element 46.

(83) When the step 54 and the face 53 of the tool 5 are respectively in contact with the contact surface 23 and the sliding surface 22 of the first jaw 2, the tool is clamped and ready for use (FIG. 9b).

(84) During clamping the second jaw can move slightly with respect to the guide pins 63 and to the control pin 61 so as to adjust, once clamped, with respect to the first jaw at a height that ensures perfect contact between the face 53 of the tool and the contact surface 23 of the first jaw.

(85) With reference to FIG. 10 there is represented the step of release of the two jaws for removal of the tool 5.

(86) The control pin 61 is rotated in the direction of unscrewing from the first jaw 1 so as to enable translation of the second jaw 3 away from the first jaw 2. In this condition the weight of the tool 5, discharged onto the engaging surface 46 of the retaining tooth 41, causes a gradual downward sliding of the safety hook 4 until the lower end thereof is resting against the stop foot 37 of the second jaw 3.

(87) As occurs during the step of insertion of the tool, the slope of the thrust surfaces 36 and of the related rest surfaces 43 ensure that the safety hook 4, during descent, remains pushed towards the face 56 of the shank 51 so that the retaining tooth 41 remains engaged in the groove 52.

(88) For extraction of the tool 5, as illustrated in FIGS. 11a-11d it is necessary to exert thereon an upward vertical thrust until the top 57 of the shank 51 reaches and rests on the lower face 45a of the cantilever portion 45 (FIG. 11a).

(89) From this position, continuing to push upwards, the top 57 of the shank generates a thrust on the cantilever portion 45, which in turn draws the safety hook 4 upwards, always in a direction parallel to the thrust plane P.

(90) After reaching a position of maximum height, in which the stop surfaces 79 and 70, respectively of the second jaw 3 and of the safety hook 4, are in contact with each other, the safety hook 4 stops its travel (FIG. 10b).

(91) At this point it is necessary to apply a direct force on the tool 5 towards the second jaw 2, as shown by the arrow in FIG. 11c. In this way, the top 57 of the shank 51 slides along the lower face 45a of the cantilever portion 45 until the face 53 of the shank 51 stops on the sliding surface 22 of the first jaw 2.

(92) In this position, the retaining tooth 41 exits from the groove 52 of the shank 51.

(93) From this position it is sufficient to draw the tool 5 rapidly downwards so that the shank descends without the retaining tooth 41 interfering with the groove 52 of the shank 51 (FIG. 10d). Once said groove 52 is no longer in the area of action of the retaining tooth 41 it is sufficient to exert a downward pulling action to remove the tool 5 completely from the jaws.

(94) Advantageously, during this step the retaining means 75 contribute to slowing the descent of the safety hook 4 preventing the retaining tooth 41 from re-entering the groove 52 of the shank before passing beyond it.

(95) More in detail, during descent of the safety hook 4, the head 78b of the pin 78 compresses the spring 76, which slows the travel of the safety hook 4.

(96) As will be clear from the description above, the present invention solves the problems that affect prior art devices achieving the set objects.

(97) In detail the locking device enables operations for installation and/or removal of one or more tools to be performed simply, rapidly and safely. In fact, the particular structure of the safety hook 4 together with that of the second jaw 3 ensures that the tool 5 is maintained suspended between the jaws both before clamping and after release thereof.

(98) In particular, the structure of the safety hook 4 and of the second jaw 3 ensure that any accidental impacts or knocks sustained by the tool cannot cause the release thereof. In fact, even if the tool is rotated with respect to the shank, the safety hook 4, thanks to fact that it can slide freely and to its weight, tends always to return to the lowered position in which it is moved towards the first jaw 2 and in which the retaining tooth 41 is able to engage the groove 52 of the shank.

(99) The locking device of the present invention also has a mechanically sturdy, simple and reliable structure.

(100) The present invention, as described and illustrated, may be subject to various modifications and variants, all of which fall within the scope of the invention; furthermore, all the details may be replaced with other technically equivalent elements.