FORMPRESSE

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a press for moulding components, for example for moulding metal parts, in particular a press with additional punch devices.STATE OF PRIOR ART

[0002] In the field of manufacturing small components, e.g. metal components, it is well known to use presses to suitably shape parts by plastic deformation, usually in a hot working condition.

[0003] Presses typically consist of a workpiece holder placed on the press basement, a first main mould that descends vertically on the workpiece holder, and a plurality of punches that converge radially on the workpiece holder by means of a pair of drive rods and are inserted in different directions in the mould to form other shapes (typically cavities) in different planes of the workpiece.

[0004] Some representative examples of the known technique, included herein for reference, are disclosed in IT102009901695822, EP3769949, and IT102014902291554. In WO2023 / 031767, forming the basis for the preamble of claim 1, the pair of connecting rods is hinged to a vertical slide actuated by a drive portion of the main slide of the press. In EP2210686 the connecting rod pair is hinged to the end of a hydraulic plunger. In EP2995446 the connecting rod pair is hinged to the end of a slide in the form of a worm gear.

[0005] These prior art technical solutions, some of which share a toggle movement for driving the punches, have a general problem of energy efficiency.

[0006] In the case of a hydraulic drive, high energy consumption is linked to the need to keep a large volume of oil under pressure. When, on the other hand, the machine is driven by an electric motor, it is possible to achieve more efficient regulation and consumption closely linked to the operating phases, but the general configuration must be redesigned with respect to machines being originally designed for hydraulic drive.

[0007] The Applicant therefore found room to optimise the kinematic control lines on these presses to make them more suitable for use with electrical controls and thus make significant savings in energy consumption.SUMMARY OF THE INVENTION

[0008] The problem behind the invention is therefore to propose a moulding press with optimised configurations that reduce energy consumption, particularly in the case of electric motor drives.

[0009] A further scope of the invention is to provide a moulding press equipped with a toggle mechanism for electrically operated punches, which can be adjusted quickly, efficiently and at low cost.

[0010] These scopes are achieved through the features mentioned in the main claim. Subordinate claims describe preferred and further advantageous features of the invention.BRIEF DESCRIPTION OF THE DESIGNS

[0011] Further features and advantages of the invention will, however, be better illustrated by the following detailed description of a preferred embodiment, given purely as an example and not as a limitation, and illustrated in the accompanying drawings wherein: Fig. 1A is a side elevation view of a press according to a preferred embodiment of the invention; Fig. 1B is a sectional view taken along the B-B line of Fig. 1A; fig. 1C is a similar view to fig. 1B of a press with a vertical punch; figs. 2A and 2B are views from two different perspectives from above the press in fig. 1A; fig. 3A is a frontal elevation view of the control detail of one of the side punches according to the invention; Fig. 3B is a side elevation view taken from the right of Fig. 3A; Fig. 3C is a side elevation view taken from the left of Fig. 3A; fig. 3D is a sectional view taken according to the D-D line of fig. 3C, in a lower dead centre state of the toggle kinematics; and Fig. 3E is a cross-sectional view taken along the D-D line of Fig. 3C, in a top dead centre state of the toggle mechanism. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0012] A hot moulding press for metal parts is made of, in a way known per se, of a basement 1, equipped with a workpiece holder 1a, above which is mounted a moulding carriage structure C carrying a forming mould 2.

[0013] The moulding carriage C is slidable vertically on structural guides B and is driven downwards by means of an actuator - depending on the type of drive, also capable of delivering several tonnes of load downwards - which also performs the lifting function between one moulding stroke and the next.

[0014] In the lower part of the press, at the height of the workpiece holder 1a, there are also punch devices 3a-3c, arranged radially around a longitudinal downward axis of the mould 2. Figs. 1A-2B illustrate four lateral punch devices 3a-3c with a horizontal punch stroke and mounted at 90° to each other, but it is not excluded that they may be different in number, spaced at different angles or arranged in different directions. Fig. 1C, for example, illustrates another version of a press in which there is a central punch with a vertical stroke.

[0015] Further details of the general configuration of the moulding press and its operation will not be given here because they are well known to a skilled in the field and are also disclosed in the above-mentioned prior art documents.

[0016] The press can be controlled with an actuator, located in the upper part of the frame, of any appropriate type. Advantageously, the press can be entirely driven by electric motors.

[0017] In particular, a first press motor M 1 is arranged at the top of the press support structure and, by means of a suitable gearbox, drives a vertically movable press rod 4, which drives the moulding carriage C by means of a toggle mechanism T.

[0018] A toggle mechanism is understood, in the context of this application, to mean a transmission mechanism consisting of a pair of connecting rods mutually hinged at one drive end and linked at the opposite ends to two elements driven in opposite directions.

[0019] In the specific case of the kinematic mechanism T illustrated, the press rod 4 acts on a hinge body 5 common to two proximal ends of a pair of connecting rods 6a and 6b, the distal ends of which are linked respectively to an upper fixed block 7a of the press structure and to a lower thrust link 7b of the carriage C.

[0020] As depicted well in fig. 1B, rod 4 preferably acts on two toggle kinematic units, arranged one opposite the other with respect to a plane of symmetry, so as to symmetrically distribute the stress on carriage C. However, it cannot be excluded that even a single toggle mechanism, suitably dimensioned, can adequately fulfil its function.

[0021] The rod 4 acts on the driving ends of the two connecting rods 6a and 6b by means of an additional articulated link which allows the common pivot point of the two connecting rods to follow a curved path, approaching the connection axis between the two opposite ends of the connecting rods. In this way, at the end of the stroke of the press rod 4, the two connecting rods can be aligned on the same axis and thus mechanically support the press effort, without the need for high drive energy, to be delivered to the press rod 4.

[0022] This operating mode allows the mould to be kept under pressure on the workpiece, in the lower dead centre position, even without actuator action.

[0023] Punch devices 3a-3c are driven by an actuator, preferably an electric motor, which drives a movable carriage via a punch toggle mechanism.

[0024] According to one aspect of the invention, the punch toggle mechanism receives motion from the respective actuator via a connecting rod / crank mechanism, which in turn is driven either directly (direct drive) or via gears or another transmission mechanism.

[0025] In particular, with reference to Figs. 3A-3D, the punch device is made of - as is well known - a guide casing 10 in which a base block 11 and a longitudinally sliding carriage 12, on which a suitably shaped punch or a punch holder 12a on which the actual punch is mounted, are located. On the carriage 12 and the base block 11 are rotationally linked the distal ends of a pair of opposing connecting rods 13a and 13b which are rotationally joined, with their respective proximal ends, to a head 14a of a crank arm 14.

[0026] The two proximal ends of the connecting rods 13a and 13b protrude from the casing 10 through a lateral slit, preferably arranged in the lower part of the device, into which the head 14a of the crank arm 14 partially engages. The rotation axes of the ends of the connecting rods 13a and 13b and of the head 14a are all parallel to each other and orthogonal to the longitudinal sliding axis of the carriage 12.

[0027] According to the invention, a base end or button of the crank arm 14 is rotationally linked, for example by means of a bearing, to a thrust shaft 15 arranged eccentrically on a suitably dimensioned drive wheel 16. The longitudinal axis of the thrust shaft 15 and the rotational axis of the drive wheel 16 are also parallel to the rotational axes of the connecting rods 13a and 13b.

[0028] In the embodiment illustrated in the figures, the drive wheel 16 is part of a gear transmission assembly G, fitted inside a respective protective casing 17, which receives power traction from an electric drive motor M 2 .

[0029] The drive motor M 2 is, for example, a brushless torque type motor, linear, combined with a central drive that can be regenerative with position or torque closed-loop feedback control.

[0030] As mentioned above, drive wheel 16 can also be controlled directly by the actuator / drive motor M 2 or by other transmission.

[0031] This configuration is particularly advantageous from an energy point of view, compared to similar solutions of prior art with direct drive on the toggle mechanism. In fact, crank 14 goes from a lower dead centre position (as illustrated in fig. 3D), with carriage 12 fully back, to a higher dead centre position (as illustrated in fig. 3E) when carriage 12 is fully forward and is in the maximum effort condition: the latter condition, due to the specific transmission kinematic mechanism, can be maintained with a relatively low power supply to the motor, compared to other linear motor or recirculating ball transmission configurations.

[0032] Preferably, as also mentioned above for the toggle mechanism T, at the top dead centre of the crank arm 14 (fig. 3E), the two connecting rods 13a and 13b are aligned on the same axis, so that the load is discharged onto the two connecting rods, without the need for delivering high drive energy to maintain this position.

[0033] In order to adjust the stroke of the carriage 12 and adapt it to the specific workpiece to be punched, the longitudinal position of the base block 11, inside the casing 10, can be adjusted.

[0034] According to one aspect of the invention, for this purpose, it is advantageously provided that the base block 11 is also mounted longitudinally slide-adjustable in the casing 10, being set in abutment against an adjusting assembly R. In particular, the base block 11 has at least one inclined flat surface at the back (i.e. on the opposite side with respect to the connecting rod link point 13b), which is slidingly coupled - for example by means of a dovetail coupling or the like - with at least one corresponding inclined flat surface of the adjustment assembly R.

[0035] The slope angle of the aforementioned inclined surfaces, in relation to a plane orthogonal to the longitudinal adjustment axis, is modest (e.g. in the order of 2°-25°), so as to ensure a certain irreversibility of the adjustment movement.

[0036] Preferably, the adjustment assembly R has a first sliding block 18a and a second retaining block 18b, which are coupled to each other by means of a drive shaft 19. The latter is rotatably mounted but axially integral in the second retaining block 18b and has a helical screw portion 19a which is coupled in a corresponding helical nut bore of the first sliding block 18a.

[0037] The drive shaft 19 has a longitudinal axis arranged orthogonal to the longitudinal adjustment direction of the base block 11 and is driven in rotation by an electric adjustment motor M 3 . A transmission with a high transmission ratio, for example a bevel gear or a worm and nut transmission, is preferably provided between the electric adjustment motor M 3 and the drive shaft 19. Said transmission is preferably configured in such a way that the axis of rotation of the motor M 3 is orthogonal to the axis of rotation of the drive shaft 19, as illustrated in Figs. 3A-3E, which makes better use of the available space.

[0038] Further, the second retaining block 18b is removably attached to the casing 10, e.g. by means of transverse fixing pins to a bottom 10a of the casing 10.

[0039] For greater constraint efficiency, the sliding block 18a and the retaining block 18b are L-shaped (as well shown in Fig. 3D) and are a mutually arranged in an inverted manner, so that they face each other with their smaller sides and have their larger sides respectively to mate with the base block 11 and to connect with the bottom 10a.

[0040] With this configuration, the adjustment motor M 3 rotates the drive shaft 19 in one of the two directions, causing the displacement of the slide block 18a with respect to the retaining block 18b in a direction orthogonal to the longitudinal adjustment axis of the base block 11: the latter thus moves back and forth by an amount determined by the transmission ratio due to the angle of inclination of the inclined surfaces. A reverse movement, which could theoretically occur due to the action applied by the connecting rod 13b on the base block 11, during the operation of the press, is in fact prevented by the irreversibility of the kinematic chain from the motor M 3 to the base block 11.

[0041] As can be understood from the above description, the solution of the invention applied to a moulding press perfectly achieves the intended scope stated in the introduction.

[0042] In particular, the toggle drive kinematic motion of the moulding carriage lends itself perfectly to an electric drive with low current consumption; at the same time, the crank-rod drive unit of the punch device allows for dead centre conditions that make its operation particularly energy-efficient, particularly with an electric motor drive. Finally, the stroke adjustment mechanism in the punch device is particularly simple and therefore allows for economy in construction and maintenance, as well as effective adjustment using a low-consumption electric motor.

[0043] It is understood, however, that the invention is not to be considered limited to the particular embodiments illustrated above, which are only illustrative and preferred embodiments, but that several variants are possible, all within the reach of a person skilled in the art, without thereby departing from the scope of the invention itself, as defined by the following claims.

[0044] For example, between the upper actuator M 1 and the first toggle assembly T, an additional control kinematic mechanism can be provided, e.g. a crank-rod control such as that provided between the actuator M 2 and the respective punch toggle kinematic mechanism.

Claims

1. Moulding press comprising a lower basement (1) equipped with a workpiece holder (1a), a deformation mould (2) attached to a moulding carriage (C) mounted vertically movable above said basement (1) by means of a power actuator (M1), and a plurality of punch devices (3a-3d), converging radially towards said workpiece holder (1a), wherein said punch devices (3a-3d) have at least a punch carriage (12) sliding longitudinally in relation to a base block (11) by means of a punch actuator (M2), and a toggle drive mechanism provided with a pair of connecting rods (13a, 13b), said connecting rods (13a, 13b) being respectively linked to said punch carriage (12) and to said base block (11) on the one hand, characterized in that said connecting rods (13a, 13b) are linked to a crank head (14a) of a crank arm (14) on the other hand, a base end of said crank arm (14) being hinged in rotation to a thrust shaft (15) arranged eccentrically on a wheel (16) driven by said punch actuator (M2).

2. Moulding press as in claim 1, wherein said punch actuator (M2) is an electric motor.

3. Press as in 2 or 3, wherein a longitudinal axis of said thrust shaft (15) and a rotational axis of said wheel (16) are parallel to rotational axes of said pair of connecting rods (13a, 13b).

4. Press as in claim 1, 2 or 3, wherein said wheel (16) is part of a gear drive assembly (G) which receives power drive from said punch actuator (M2).

5. Press as in any one of the preceding claims, wherein between said power actuator (M1) and said moulding carriage (C) a transmission (T) comprising at least one toggle assembly (5, 6a, 6b) is provided.

6. Press as in claim 5, wherein there are provided two toggle assemblies (5, 6a, 6b) arranged specularly with respect to a plane of symmetry along which drive means (4) are slidingly mounted.

7. Press as in claim 6, wherein said drive means comprise at least one drive rod (4) driven by at least one electric power motor (M1).

8. Press as in any one of the preceding claims, wherein said base block (11) is mounted adjustable sliding longitudinally in a housing casing (10) and is set abutting against an adjusting assembly (R) by means of a single inclined surface coupling.

9. Press as in claim 8, wherein said adjusting assembly (R) has a first sliding block (18a) and a second retaining block (18b), which are coupled to each other by means of a drive shaft (19) rotatably mounted but axially integral in said second retaining block (18b) and provided with a helical screw portion (19a) coupled in a corresponding helical nut bore of said first sliding block (18a), wherein said first sliding block (18a) has a sloping flat surface slidingly coupled with a corresponding flat sliding surface of said base block (11), and said second retaining block (18b) is secured against said casing (10).

10. Press as in claim 9, wherein said drive shaft (19) has a longitudinal axis arranged orthogonal to a longitudinal adjustment direction of said base block (11) and is rotating driven by an electric adjustment motor (M3)