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(11) | EP 1 057 551 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A multiple punch unit and a machine tool provided with such multiple punch unit |
| (57) The multiple punch unit (18) comprises: a cassette (21) supporting the punch units
(31); a cylindrical body (34) housed within the said cassette (21) and supporting
a striker (36); and a device a part of which is movable between a first position in
which the cassette (21) and the body (34) are fixed together for rotation and a second
position in which these elements are freely rotatable with respect to one another,
the second position selects a tool (31) carrying the striker (36) into alignment therewith,
and the first position allows the angular orientation of the selected tool (31) to
be determined. |
[0002] The present invention also relates to a machine tool for working sheet metal provided with an innovative multiple punch unit.
[0003] As is known, a multiple punch unit comprises a single tool holder cassette within which a plurality of punches are installed in a circle.
[0004] A first type of multiple punch unit has a body installed within the tool holder cassette supporting a striker and rotating about a vertical axis to bring the striker into alignment with a pre-selected punch. A second type of multiple punch unit has a body installed within the cassette and supporting the striker; the cassette being rotatable about a vertical axis to carry the pre-selected punch into alignment with the striker. The main disadvantage of these multiple punch units essentially lies in the impossibility of orientating the punch at will, that is to say the impossibility of controlling the cutting angle the punch assumes. Consequently it is necessary to install in the unit several similar punches each with a given orientation.
[0005] A third type of multiple punch unit provides an external striker outside the tool holder cassette and rotatable about a vertical axis to bring a projection thereof into alignment with a pre-selected punch; the cassette being rotatable about the said vertical axis to orientate the pre-selected punch. The main disadvantage of this type of multiple punch unit lies in its large dimensions and in the complexity of construction in that two different motor drives are needed, one for the cassette and the other for the striker.
[0006] The object of the present invention is that of providing a multiple punch unit which will be free from the above-mentioned disadvantages.
[0007] A further object of the present invention is that of providing a machine tool having a multiple punch unit free from the above-mentioned disadvantages.
[0008] According to the present invention there is provided a multiple punch unit characterised in that it comprises:
a cylindrical cup-shape cassette having a base wall and a cylindrical side wall;
a disc housed coaxially within the said cassette, fixed for rotation with the said cassette but axially displaceable with respect thereto and supporting a plurality of punch tools each of which passes through a respective first hole formed in the said base wall;
a cylindrical body coaxially housed within the said cassette and supporting a striker; and
a device having a part movable between a first position in which the said cassette and the said body are fixed for rotation with one another and a second position in which the said cassette is free to rotate with respect to the said body, the said second position allowing selection of one of the said punch tools and then bringing the said striker into alignment with a predetermined punch tool, and the said first position allowing determination of the angular orientation of the said selected punch tool.
[0009] According to the present invention there is likewise provided a machine tool for punching a metal sheet comprising:
a work table on which the said sheet metal rests;
a work unit acting to perform the work on the said metal sheet;
means for moving the said metal sheet over the said work table to and from the said work unit; and
an electronic central control unit for the management of the working cycle, which
controls the said work unit and the said means;
characterised in that the said work unit comprises a multiple punch unit as defined
hereinabove.
[0010] The present invention will now be described with reference to the attached drawings which illustrate a preferred, non-limitative embodiment thereof, in which:
Figure 1 is a partly sectioned side view of a punching machine;
Figure 2 is a sectioned view of a punch unit and a die unit; and
Figure 3 is a plan view of a component of the punch unit of Figure 2.
[0011] As illustrated in Figure 1 a machine tool generally indicated 1 for working sheet metal 2 comprises:
a work table 3 supported by a base 4 and on which the metal sheet 2 rests;
a work unit 5 acting to perform the work on the metal sheet 2;
means 6 for moving the metal sheet 2 over the work table 3 to and from the said work unit 5; and
an electronic central control unit 7 for managing the working cycle, which controls the work unit 5 and the means 6.
[0012] On the work table 3 it is possible to identify two orthogonal horizontal axes along which the means 6 can move the metal sheet 2.
[0013] The work unit 5 comprises:
an upper turret 8 rotating about a vertical axis Z and supporting a plurality of punch units 11 in a circle;
a lower turret 12 rotating about a vertical axis Z' and supporting a plurality of die units 13 in a circle;
a hammer 14 acting, during the punching phase, to translate along a vertical axis M;
a motor drive device 15 for the turret 8;
a motor drive device 16 for the turret 12; and
a device 17, preferably of fluid dynamic type, for controlling the stroke of the said hammer 14.
[0014] In this embodiment the axes Z and Z' about which the turrets 8 and 12 rotate are separate although in a different embodiment, which nevertheless lies within the protective ambit of the present invention, these axes Z and Z' could be coincident.
[0015] At least one of the punch units 11 carried by the turret 8 is a multiple punch unit and is illustrated in Figure 2 as multiple punch unit 18 which comprises a cassette 21 shaped like a cylindrical cup and rotatable about its vertical longitudinal axis P. The cassette 21 has a bottom wall 22 and an annular side wall 23 which extends upwardly from the peripheral rim of the bottom wall 22. Close to the bottom wall 22, but at a given distance from it, and within the cassette 21 there is installed a disc 24 having an axis P fixed for rotation with the cassette 21 by means of a key 25 carried by the wall 23 and engaging an axial groove 26 formed on the lateral face of the disc 24.
[0016] With reference to Figure 2, the disc 24 is movable along the axis P and between it and the bottom wall 22 there is installed a coil spring 27 opposing the translation of the disc 24 towards the bottom wall 22. The disc 24 has around its periphery a plurality of vertical through holes 28. The disc 24 supports a plurality of punch tools 31 each having a shank 31a which traverses a respective hole 28, and a head 31b which rests on the upper face of the disc in correspondence with the edge of the respective hole 28. The bottom wall 22 has around its periphery a plurality of vertical through holes 32 coaxial with the holes 28. The shank 31a lies within a corresponding hole 32 and its tip projects from the hole 32 up to the interior of a recess 33 formed on the lower face of the bottom wall 22.
[0017] With reference to Figure 2, in the upper part of the cassette 21 is housed a cylindrical body 34 having an axis P, downwardly from the lower face of which extends a cylindrical projection 35 having an axis P and of length greater than the stroke of the punch tool 31 during the punching phase. The projection 35 has a smaller diameter and is in engagement with the upper face of the disc 24. From the lower face of the body 34 on the same side as the projection 35 a striker 36 fixed to the body 34 by means of a fixing screw 37 extends downwardly along a vertical axis A. Between the lower face of the body 34 and the upper face of the disc 24 there is installed a cylindrical pad 39 on the axis P, which is pressed against the heads 31b of the punch tool 31 by a coil spring 38 installed between the pad 37 and the lower face of the body 34.
[0018] With reference to Figure 2, the pad 37 has a through hole 40 on the axis P traversed by the projection 35. The pad 37 further has a second through hole 41 having an axis A traversed by the striker 36 the lower end of which comes into contact with the head 31b of one of the punch tools 31. In the body 34 is formed a through hole 42 having an axis P with an upper section 42a of greater length, as will be seen better hereinafter, than the stroke which the punch tool 41 performs during the punching phase, a central section 42b of smaller diameter than that of the section 42a in such a way as to define in the section 42a an annular shoulder 43, and a lower section 42c of greater length, as will be seen in more detail hereinafter, than the stroke which the punch tool 31 performs during the punching phase and a greater diameter than that of the section 42b in such a way as to define therein an annular shoulder 44. A pin 45 having an axis M axially fixes the cassette 21 and the body 34 together. The pin 45 traverses the sections 42b and 42c of the hole 42, the hole 40 of the pad 39, a through hole 46 formed in the disc 24, and a through hole 47 formed in the bottom wall 22. The pin 45 allows the body 34 to rotate about the axis M with respect to the cassette 31. From the top towards the bottom the pin 45 has a head 45a which engages the shoulder 43, a section 45b housed in the sections 42b and 42c, an annular projection 45c housed in the section 42c and in contact against the disc 24, a section 45d housed in the holes 46 and 47, and an end fixed by means of a screw to the bottom wall 22.
[0019] With reference to Figure 2, the turret 8 has a through hole 48 on the axis P engaged by a sleeve 51 housing the lower part of the cassette 21. A key 52 carried by the turret 8 by a known means 52a between a position in which it extends into an axial groove 53 formed in the wall 23 to prevent rotation of the cassette 21 about the axis P, and a disengaged position in which it lies outside this groove 53.
[0020] With reference to Figure 2, the cassette 21 supports a cylindrical sleeve 54 on the axis P and a lower portion which lies inside the upper part of the wall 25 and an upper portion which lies within the upper part of the body 34. In particular, on the inner face of the upper portion of the sleeve 54 is formed a toothed annular zone 55 meshing with a toothed annular zone 56 formed on the outer face of the upper part of the body 34. Any rotation of the sleeve 54 about the axis P involves the same rotation of the body 34.
[0021] With reference to Figures 2 and 3, at the upper end of the sleeve 54 are formed four uniformly distributed notches which are therefore at 90° from one another; two first diametrically opposite notches are indicated 57a and two second notches adjacent these latter are indicated 57b. A vertical hole 58 is formed in the sleeve 54 in correspondence with one notch 57a, which opens into a through slot 61. A pin 62 is housed in the hole 58 and has an upper end which extends into the notch 57a and a lower end which extends into the slot 61 and which carries a key 63. The pin 62 is movable, against the action of a spring 64 housed in the slot 61, between an upper position in which the key 63 engages a toothed annular zone 65 formed at the upper end of the part 23, and a lower position in which the key is disengaged from the toothed zone 65. When the pin 62 is in the upper position rotation of the sleeve 54 about the axis P involves an equal rotation both of the cassette 21 and therefore the disc 24, and of the body 34. When the pin 62 is in the lower position a rotation of the sleeve 54 about the axis P involves an equal rotation only of the body 34.
[0022] With reference to Figures 1 and 2, the machine 1 includes a device 71 for selection of the punch tool 31 to be utilised and for the adjustment of the angular orientation of the selected punch tool 31. The device 71 comprises an annular body 72 on axis M, two vertical teeth 73 which extend downwardly from the lower end of the body 72 and which are diametrically opposite one another, and means 74 for rotation of the body 72 about the axis M and for vertical translation of the body 72.
[0023] With reference to Figure 2, the die unit 13 comprises a cassette 75 having a vertical axis T, housed, with the interposition of a sleeve 76, within a vertical through hole 77 formed in the turret 12. The cassette 75 houses a cylindrical body 78 centred on axis T with a plurality of vertical through holes 81 in a ring, each of which is engaged by a corresponding die tool 82; in use, when the axis P of the multiple punch unit 18 and the axis T of the die unit 13 are coaxial with the axis M of the hammer 14 the holes 81 are coaxial with respective holes 32 such that each punch tool 31 is coupled with a corresponding die tool 82. The body 78 is fixed against rotation with respect to the cassette 75. A key 83 carried by the turret 12 is able to translate, by means 84 of known type, between an engaged position in a groove 85 formed in the cassette 75 in such a way as to prevent rotation of this, and a disengaged position in which the cassette 75 is free to rotate about the axis T.
[0024] With reference to Figure 2, at the lower end of the cassette 75 are formed four notches 86 uniformly distributed at 90° from each other. The machine 1 includes a device 87 for selection of the die tool 82 to be utilised and for adjusting the angular orientation of the selected die tool 82. The device 87 includes an annular body 88 on axis T, two vertical teeth 91 which extend upwards from the upper end of the body 88 and which are diametrically opposite one another, and means 92 for rotation of the body 88 about the axis T and for vertical translation of the body 88.
[0025] In use, by rotating the turrets 8 and 12 the multiple punch unit 18 and the corresponding die unit 13 are brought into alignment with the hammer 14. Now, at first the body 72 turns until the teeth 73 are in alignment with the notches 57a, then the body 72 translates downwardly until the teeth 73 engage the notches 57a and one of the teeth 73 disengages the key 63 from the toothed zone 65 by means of the pin 62, and finally the body 72 turns in such a way as to bring the striker 36 into alignment with the punch tool 31 to be utiised. Once the punch tool 31 has been selected, first the body 72 translates upwardly in such a way as to disengage the teeth 73 from the notches 57a, then the body 72 turns through 90°, subsequently the body 72 translates downwardly until the teeth 73 engage the notches 57b and finally the body 72 turns until, with the same rotation of the cassette 21 and the body 34, it reaches the pre-selected angular orientation of the selected punch tool 31. During this later operation the cassette 75 turns by means of the device 87 in such a way as to make the die tool 82 coupled to the selected punch tool 31 reach the same angular orientation. Naturally, during rotation of the cassettes 21 and 75 these must be free to rotate and therefore the respective keys 52 and 83 are in the disengaged position. Now, by actuation of the hammer 14 it is possible to punch the sheet metal 2 with the selected punch tool 31. During the punching phase the body 34 translates downwardly and causes an equal translation of the striker 36 which acts only on the selected punch tool 31; the bottom wall 22 acting as a sheet presser.
[0026] The advantages of the machine tool 1 and the multiple punch unit 18 formed according to the principles of the present invention are evident and numerous.
[0027] In particular, a compact multiple punch unit, therefore having reduced dimensions, is formed incorporating therein the punch tools and the striker. Moreover it is possible easily to select the punch tool to be utilised and it is possible to determine with ease the angular orientation at which the punch tool is to be set.
a cylindrical cup-shape cassette (21) having a bottom wall (22) and a cylindrical side wall (23);
a disc (24) coaxially housed within the said cassette (21) fixed for rotation with and free to move axially with respect to the said cassette (21), and supporting a plurality of punch tools (31) each of which passes through a respective first hole (32) formed in the said bottom wall (22);
a cylindrical body (34) coaxially housed within the said cassette (21) and supporting a striker (36); and
a device having a part movable between a first position in which the said cassette (21) and the said body (34) are fixed for rotation together and a second position in which the said cassette (21) is free to rotate with respect to the said body (34), the said second position allowing one of the said punch tools (31) to be selected and then the said striker (36) brought into alignment with a predetermined punch tool (31), and the said first position allowing angular orientation of the said selected punch tool (31) to be determined.
a work table (63) on which the said metal sheet (2) is supported;
a work unit (5) which can work the said metal sheet (2);
means (6) for moving the said metal sheet (2) over the said work table (3) to and from the said work unit (5); and
an electronic central control unit (7) for management of the working cycle, which
controls the said work unit (5) and the said means (6);
characterised in that the said work unit (5) comprises a multiple punch unit (18)
as claimed in any preceding claim.
an upper turret (8) rotating about a vertical axis (Z) and supporting a plurality of punch units (11) in a ring around its periphery, of which at least some are the said multiple punch units (18);
a lower turret (12) rotating about a vertical axis (Z') and supporting a plurality of said die units (13) in a ring around its periphery;
a hammer (14) acting, during the punching phase, to translate along a vertical axis;
a device (15) for motorization of the said upper turret (8);
a device (16) for motorization of the said lower turret (12); and
a device (17), preferably of fluid dynamic type, for controlling the stroke of the said hammer (14).