UNIT FOR BROACHING RULES OF DIE CUTTERS AND METHOD TO PERFORM THE BROACHING OF A RULE FOR DIE CUTTERS

Abstract

A broaching unit for rules of die cutters which comprises a supporting structure, for example a frame, a guide of a die cutter rule, and a tool-holding arm equipped with at least one broaching tool is described. The guide defines a sliding surface on which the rule is fed intermittently. The tool-holding arm is mounted on the supporting structure and is susceptible to reciprocating movements with respect to it and with respect to the guide, preferably forward and backwards movements along a transversal direction of the rule, just to intercept the die cutter rule with the broaching tool when the rule is stopped. Advantageously, the tool-holding arm is equipped with at least two broaching tools, for example four tools, and can be oriented with respect to the guide, for example can rotate on itself, to selectively activate one of the broaching tools, i.e. to bring one of the tools into contact with the rule.

Claims

1. A unit (1) for broaching rules of die cutters, comprising a supporting structure (2), a guide (3) of a die cutter rule (4) and a tool-holding arm (5) equipped with a broaching tool (6), wherein the guide (3) defines a sliding surface of the die cutter rule (4), and wherein the tool-holding arm (5) is mounted on the supporting structure (2) and is susceptible to reciprocating movements with respect to it and the sliding surface, to intercept the die cutter rule (4) with the broaching tool (6), characterized in that the tool-holding arm (5) is equipped with at least two broaching tools (6-6′″) and can be oriented with respect to the sliding surface to selectively actuate one of the broaching tools (6-6′″).

2. Broaching unit (1) according to claim 1, wherein the tool-holding arm (5) extends along a skewed longitudinal axis (X-X) with respect to said sliding surface.

3. Broaching unit (1) according to claim 2, wherein the tool-holding arm (5) is rotatable on said longitudinal axis (X-X) to direct a single broaching tool (6-6′″) towards the sliding surface of the die cutter rule (4), and therefore towards a side of the die cutter rule (4).

4. Broaching unit (1) according to claim 3, wherein the tool-holding arm (5) is lockable in an angular position corresponding to one of its broaching tools (6-6′″) facing the sliding surface of the die cutter rule (4).

5. Broaching unit (1) according to claim 1, wherein the broaching tools (6-6′″) are interchangeable on the tool-holding arm (5).

6. Broaching unit (1) according to claim 1, comprising at least two tool-holding arms (5, 5′) arranged on opposite sides with respect to said sliding surface, to allow the machining of the two sides of the die cutter rule (4), or on the same side.

7. Broaching unit (1) according to claim 6, wherein each of the two tool-holding arms (5, 5′) is movable alternately and/or directable, independently of the other tool-holding arms (5, 5′) or jointly thereto.

8. Broaching unit (1) according to claim 1, wherein the guide (3) is integral with the supporting structure (2) and the tool-holding arms (5, 5′) extend cantileverly from the supporting structure (2) and slide with respect to it between an advanced, or distal, position and a retracted, or proximal, position, and one of the broaching tools (6-6′″) intersects the sliding surface of the die cutter rule (4) between the advanced and retracted positions.

9. Broaching unit (1) according to claim 8, comprising a first actuator (7) shared among the tool-holding arms (5, 5′), which imparts alternated movements to the tool-holding arms (5, 5′) between the advanced and retracted positions or, alternatively, the broaching unit (1) comprises an independent actuator for each tool-holding arm (5, 5′).

10. Broaching unit (1) according to claim 9, wherein said first actuator (7) comprises a worm screw (8) rotatably mounted on the supporting structure (2), a motor (9) activable to rotate the worm screw (8), and a carriage, or shuttle, (10), engaging the worm screw (8) and susceptible of moving along the worm screw (8) in both directions, in response to the rotations imparted on the same worm screw (8) in both directions, and wherein the tool-holding arms (5, 5′) are translationally integral with the carriage (10).

11. Broaching unit (1) according to claim 1, wherein the guide (3) is integral with the supporting structure (2) and the tool-holding arms (5, 5′) extend cantileverly from the supporting structure (2) and are each rotatable on their own longitudinal axis (X-X).

12. Broaching unit (1) according to claim 11, comprising a second actuator (11) shared among the tool-holding arms (5, 5′), which imparts the rotations to the tool-holding arms (5, 5′) on the relative longitudinal axis (X-X) or, alternatively, the broaching unit (1) comprises an independent actuator for each tool-holding arm (5, 5′).

13. Broaching unit (1) according to claim 12, wherein said second actuator (11) comprises a pulley or a cogwheel (12) coupled to each tool-holding arm (5, 5′), a motor (13) and a drive belt or gearing chain (13′) connected to the motor (13) and to the pulleys/cogwheels (12), wherein said motor imparts intermittent rotations.

14. Broaching unit (1) according to claim 1, comprising, for each tool-holding arm (5, 5′), a tracer device (14) preferably housed in the guide (3) and comprising a foot (15) movable from an active position, at which it abuts against the die cutter rule (4) located in the guide (3), on the opposite side with respect to the corresponding tool-holding arm (5, 5′), and counters the forces applied by a broaching tool (6-6′″) on the broaching rule (4), and an inactive position, at which the foot (15) is leaned on the die cutter rule (4), or separated from it, and does not counterbalance a broaching tool.

15. Broaching unit (1) according to claim 14, comprising, for each tracer device (14), a corresponding actuator (16, 17), preferably a linear guide that extends to push the foot (15) to the relative active position and retracts to allow the return of the foot (15) to the relative inactive position.

16. A method to carry out the broaching of a rule (4) of die cutters, comprising: feeding a rule (4) intermittently on a sliding surface; moving a tool-holding arm (5, 5′) alternately forward and backwards along a transversal direction with respect to the feed direction of the rule (4), wherein the tool-holding arm (5, 5′) is provided with two or more selectively operated broaching tools (6-6′″); directing the tool-holding arm (5, 5′) with respect to the sliding surface to actuate one of the broaching tools (6-6′″) so as to make it face the rule (4) on the sliding surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Further characteristics and advantages of the invention will be better highlighted by the review of the following detailed description of a preferred, but not exclusive, embodiment illustrated by way of example and without limitations, with the aid of the accompanying drawings, in which:

[0048] FIG. 1 is a perspective front view of a broaching unit according to the present invention;

[0049] FIG. 2 is a perspective back view of the broaching unit shown in FIG. 1, with some parts not shown for greater clarity;

[0050] FIG. 3 is a perspective front view of the broaching unit shown in FIG. 1, partially disassembled and in a first configuration;

[0051] FIG. 4 is a perspective front view of the broaching unit shown in FIG. 1, partially disassembled and in a second configuration; and

[0052] FIG. 5 is a perspective and enlarged view of a portion of the broaching unit shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0053] FIGS. 1-5 show the preferred embodiment of the broaching unit 1 according to the present invention, intended to be mounted on a machine for processing metal strips intended to be transformed into rules 4 for die cutters. The unit 1 comprises a supporting structure 2, in practice a metal frame or a metal framework, whose task is to support the components of the unit 1.

[0054] One of the components is a guide 3 which defines a sliding surface for a die cutter rule 4. The guide 3 thus defines the path along which the rule 4 is intermittently fed, to allow the other components of the unit to perform the broaching. As can be noted in the figures, in the example shown, the sliding surface is horizontal and thus the rule 4 is oriented with a side facing above, the upper side, and a side facing below, the lower side.

[0055] The means intended for feeding the rule 4 in the guide 3 can be means of the broaching unit 1, for example opposite wheels which rotate on the two sides of the rule 4, or can be means outside of the unit 1, such as in the example shown in the figures.

[0056] The supporting structure 2 comprises two vertical sides 2′ and 2″ and at least one tool-holding arm 5, preferably two tool-holding arms 5 and 5′, as shown in the figures. In general, however, there can also be more than two tool-holding arms, depending on the necessity.

[0057] The tool-holding arms 5 and 5′ are mounted on the supporting structure 2 and extend cantileverly from the side 2″. The reference X-X denotes the longitudinal axis of the arm 5: the arms 5 and 5′ can be translated on the relative longitudinal axis X-X in both directions, in response to the thrusts imparted by a first actuator 7 which will now be described with particular reference to FIG. 2. Preferably, the arms 5, 5′ are supported on the side 2″ of the supporting structure 2 and on the guide 3 by means of bearings or bearing brasses.

[0058] The first actuator 7 comprises a first electric motor 9 constrained to the supporting structure 2 and equipped with a pulley 18 coupled to the shaft of the motor 9 itself. The pulley 18 in turn actuates another pulley 19 by means of a belt 20. The pulley 19 rotates a worm screw 8 along which a carriage, or shuttle, 10 is positioned. The carriage 10 engages the worm screw 8 and, in response to the clockwise and counterclockwise rotations of the screw 8, moves towards the side 2″ of the supporting structure or away therefrom. The tool-holding arms 5 and 5′ are translated integrally with the carriage 10, which thus controls the forward and backwards movements along the respective longitudinal axes X-X.

[0059] The first actuator 9 is in common with the two tool-holding arms 5, 5′, i.e. it is shared: the translations of the two arms 5, 5′ occur synchronously. However, it is possible to achieve a broaching unit 1 with an actuator for each arm 5, 5′, so that to make them completely independent.

[0060] The arms 5 and 5′ are each provided with at least two broaching units 6, 6′. In the example shown in the figures, the arms 5, 5′ each comprise four broaching tools 6, 6′, 6″, 6′″. Only one of the tools 6-6′″ is active at a given time and interacts with the rule 4 in the guide 3, during the forth and back runs of the relative arm 5, 5′, and removes material from the rule 4.

[0061] More in detail, the broaching tools 6-6′″ are arranged on the end of the tool-holding arms 5, 5′ angularly staggered. In the example shown in the figures, the angular staggering is of 90°, but can generally be different, depending on the necessity and number of broaching tools present. Preferably, the tools 6-6′″ are interchangeable, i.e. can be easily separated from the relative arm 5, 5′ to be replaced with another tool.

[0062] With particular reference to FIGS. 1-2, the unit 1 comprises a second actuator 11 whose task is to rotate the tool-holding arms 5, 5′ to change the tool 6-6′″ which must perform the broaching. The second actuator 11 comprises a second electric motor 13 equipped with a pulley. A belt 13′ transmits the rotations to two pulleys 12′, one for each tool-holding arm 5, 5′. The pulleys 12 each rotate on the corresponding axis X-X but do not move axially with respect to the side 2″ of the supporting structure 2: the arms 5 and 5′ are in fact slidable inside the respective pulleys 12 (FIG. 2). For example, in the position shown in the figures, the arm 5 engages the lower side of the rule 4 with the tool 6′ and the arm 5′ engages the upper side of the rule 4 with the tool 6′″.

[0063] Therefore, when the first actuator 7 is operating, the second actuator 11 is stopped, and the arms 5, 5′ translate forward and backwards but do not rotate on the axis X-X. When the second actuator 11 is operating, the first actuator is stopped, and the arms 5, 5′ rotate to change the tool 6-6′″ which must engage the rule 4, but do not translate forward and backwards along the axis X-X.

[0064] Thus, advantageously, when it is necessary to change the tool 6-6′″ to perform the broaching of the rule 4, for example when it is necessary to use a tool of a different shape, it is sufficient to stop the first actuator 7 and to activate the second actuator 11 until the arms 5, 5′ rotate by the angle necessary to bring the desired tool 6-6′″ in front of the rule 4. Thus the rotation of the arms 5, 5′ is locked, for example with a braking device (not shown) or with the same motor 13, and the first actuator 7 is reactivated to perform the broaching.

[0065] The second actuator 11 is in common with the two tool-holding arms 5, 5′, i.e. it is shared: the translations of the two arms 5, 5′ occur in opposite direction. However, it is possible to achieve a broaching unit 1 with an actuator for each arm 5, 5′, so that to make them completely independent.

[0066] In the example shown in the figures, the guide 3 is defined in a box-like structure 21, which also houses other components of the unit 1, as will now be described, and through which the arms 5, 5′ slide. In particular, the box-like structure 21 is shown complete in FIGS. 1-2, and is instead partially disassembled in the remaining FIGS. 3-5 in order to show the other components.

[0067] In addition to the guide 3, the box-like structure 21 houses a tracer device 14 for each tool-holding arm 5, 5′. The tracer device 14 comprises a foot 15 movable between: [0068] an active position, at which it abuts on the corresponding side of the rule, the upper one or the lower one, depending on the case, from the opposite side with respect to the corresponding tool-holding arm 5, 5′; and [0069] an inactive position, at which the foot 15 is leaned on the rule 4 without exerting a thrust, or is separated from the die cutter rule 4, i.e. is raised with respect to it and does not interact with the rule 4.

[0070] In practice, the foot 15 balances the pressure exerted by the broaching tool 6-6′″ when it removes material from the rule 4, during the longitudinal movement of the arms 5, 5′. This circumstance is well shown in FIG. 5: the foot 15 is in abutment against the upper side of the rule 4, waiting for the tool 6′ of the arm 5 to perform the broaching.

[0071] Each of the two tracer devices 14 is actuated by a corresponding actuator 16 or 17: in the example shown, it is a linear guide that extends from the side 2″ of the supporting structure 2 to push the foot 15 to the relative active position, and retracts towards the side 2″ to allow the return of the foot 15 to the relative inactive position, if necessary thanks to the intervention of a countering elastic element.

[0072] In particular, the foot 15 slides in a bushing 22 housed in the box-like structure 21, along a direction orthogonal to the feed direction of the rule 4 in the guide 3. The upper part of the foot 15 is rounded and the actuator 16, 17 is in practice a finger with a beveled surface which causes the displacement in the bushing 22, towards the rule 4, by pushing on the foot 15. The backwards movement of the actuator 16, 17 allows the foot 15 to return to the inactive position. For this reason, the actuator 16, 17 is equipped with its own motor 23, possibly assisted by an elastic element such as a spring.

[0073] The operations of the unit 1 also describes the method according to the present invention, which provides for the intermittent feeding of a rule 4 on a sliding surface, such as the surface defined by the guide 3, and for the reciprocating forward and backwards movement of the tool-holding arm 5 along a direction transversal to the feed direction of the rule 4. The tool-holding arm 5 is provided with at least two selectively activable broaching tools 6-6′″. By directing the tool-holding arm 5 with respect to the sliding surface, as a result one of the broaching tools 6-6′″ faces the rule 4 on the sliding surface.