TOGGLE CLOSURE ASSEMBLY FOR INJECTION PRESS

Abstract

A toggle mould closure assembly for injection presses includes: fixed, mobile and reaction planes, mounted on columns; a control unit of the toggle, having four pairs of levers, arranged symmetrically at two sides, in upper and lower parts of the structure, interconnected by a pin and to the reaction plane and mobile plane by respective pins; and an actuation unit of the control element. The control unit is placed on the axis of the toggle in the middle of the pairs of main side levers, which have an outward movement. The control unit is connected, by control connecting rods, to the levers of the toggle connected to the reaction plane, and is placed between the central connection pin of the levers and the reaction plane. The control unit is provided with heads for connection to the connecting rods external to the reaction plane and turned towards the reaction plane.

Claims

1. Toggle mould closure assembly (100) for injection presses, comprising: a fixed plane (3), a mobile plane (2) and a reaction plane (1), mounted on columns (16), a control element (6) of the toggle, made up of four pairs of levers (4, 5), arranged symmetrically at the two sides and in the upper and lower part of the structure, connected one to the other by means of a pin (9) and to said reaction plane (1) and mobile plane (2) by means of respective pins (7.1) and (7.2), actuation means (13, 14; 30-32) of said control element (6), characterised in that: the control element (6) is placed on the axis of the toggle in the middle of the pairs of main side levers (4, 5), which have an outward movement, the control element (6) is connected, by means of control connecting rods (8), to the levers (4) of the toggle connected to the reaction plane (1), and is situated, during operation, between the central connection pin (9) of the levers (4, 5) and the reaction plane (1), the control element is provided with heads (25) for connection to the connecting rods (8) external to the reaction plane and turned towards the reaction plane, and the control element is mounted on guides attached to the reaction plane.

2. Toggle mould closure assembly (100) according to claim 1, characterised in that said control element (6) is guided on columns (24) attached at the two ends to said reaction plane (1), internally to the system of levers (4, 5).

3. Toggle mould closure assembly (100) according to claim 1, characterised in that said control element (6) is guided by a guides system which consists of sliding planes with slide shoes, or by a system of recirculating guides with ball bearing or roller slide blocks guides in which the fixed part is integral with the reaction plane (1).

4. Toggle mould closure assembly (100) according to claim 1, characterised in that said levers (4, 5) of the toggle are variable in length to achieve maximum strokes of opening independent of the main structure of the toggle.

5. Toggle mould closure assembly (100) according to claim 1, characterised in that said actuation means (13, 14) of said control element (6) comprise two pistons (14) mounted integral with the control element (6), whose rod (13) acts against said reaction plane (1).

6. Toggle mould closure assembly (100) according to claim 1, characterised in that said actuation means of said control element (6) comprise a single central piston (14) mounted integral to the reaction plane (1), whose rod (13) acts against the control element (6).

7. Toggle mould closure assembly (100) according to claim 1, characterised in that said actuation means of said control element (6) comprise two electrically operated screw actuators (30) driven by direct motors (31) integral with the reaction plane (1), which actuate the control element (6) threading in respective screw grommets (32) integral with the control element (6).

8. Toggle mould closure assembly (100) according to claim 1, characterised in that said actuation means of said control element (6) comprise a single central electric actuator acting between said reaction plane (1) and said control element (6).

9. Toggle mould closure assembly (100) according to claim 1, characterised in that said reaction plane (1) is I-shaped.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Further features of the invention will be made clearer by the following detailed description, referred to its embodiments purely by way of a non-limiting example and illustrated in the accompanying drawings, in which:

[0046] FIG. 1 is a side view, partially sectioned, of a toggle closure assembly for injection press according to the prior art, showing in the upper half the condition of mould closed and in the lower half the condition of mould open;

[0047] FIG. 2 is a perspective view of a mould closure assembly according to the invention, in the condition of mould closed;

[0048] FIG. 3 is a side elevation view of the assembly of FIG. 2;

[0049] FIG. 4 is a view from the left-hand side of FIG. 3;

[0050] FIG. 5 is a median sectioned view taken along plane V-V of FIG. 4;

[0051] FIG. 5a is a section taken along plane VA-VA of FIG. 3;

[0052] FIG. 6 is a median sectioned view like that of FIG. 5, with the toggle in the condition of mould completely open;

[0053] FIG. 6A is a median sectioned view like that of FIG. 5A, with the toggle in the condition of mould completely open;

[0054] FIG. 7 is an axonometric view of the control element of the toggle;

[0055] FIG. 8 is a plan view of the two main levers, shown separate, of an element of the toggle (double);

[0056] FIGS. 9 a), b) are, respectively, a perspective view and an end view of the reaction plane of the toggle;

[0057] FIG. 10 is a median sectioned view showing a single central piston actuator for the actuation of the control element of the levers of the toggle;

[0058] FIG. 11 is a median sectioned view showing two electric screw actuators for the actuation of the control element of the levers of the toggle.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0059] Referring to the accompanying drawings, and for the time being in particular to FIG. 2, a toggle mould closure assembly is shown for injection presses according to the present invention, in the position of mould closed, denoted overall by reference numeral 100.

[0060] The assembly is constituted mainly by a fixed plane 3, by a mobile plane 2, by a reaction plane 1, and by the control element 6 of the main levers of the toggle, denoted by reference numerals 4 and 5, connected one to the other by means of a pin 9 and to the planes 1 and 2 by means of respective pins 7.1 and 7.2.

[0061] The toggle, which is of the double type, comprises four pairs of levers 4, 5, arranged symmetrically at the two sides and in the upper and lower part of the structure, with the control element 6 (seen more clearly in FIG. 7) placed on the axis of the toggle in the middle of the pairs of side main levers. However, for reasons of simplicity, in the following description, if not absolutely necessary for the understanding of the functioning of the toggle, reference will be made thereto with reference to a single or to two pairs of levers 4, 5, accordingly.

[0062] The control of each pair of main levers 4, 5 takes place by means of a respective connecting rod 8 which connects the control element 6, which moves on a linear trajectory in axis with the toggle, and the lever 4 which rotates around the pins 7.1 and 9.

[0063] The three planes 1, 2 and 3 of the moulds assembly are connected to four columns 16 arranged at the vertices of a rectangle, having a threaded end 10, with which respective adjustment nuts 11 (FIG. 3) engage which can be regulated by means of a crown 12 (FIG. 4) on the threads 10 of the columns in order to create the distance between mobile plane 2 and fixed plane 3 such that with the toggle distended the interference is created, useful for generating the closure force in the mould placed between the mobile plane 2 and the fixed plane 3.

[0064] In the embodiment according to FIGS. 2-6, the movement of the control element 6 takes place by means of two pistons 14 placed one above and the second below the toggle. The rod 13 of the pistons is connected to the reaction plate 1; with the toggle distended, i.e. with mould closed, the pistons are completely extended.

[0065] FIGS. 5, 5A and 6, 6A represent respectively a sectioned view on the median vertical plane and a view on a horizontal plane of the toggle, respectively in the condition of mould closed and of mould completely open. In these views the structure of the control element 6 can be seen (detail of FIG. 7). The control element moves on a system of four columns 24, attached at the two ends to the reaction plane 1, apt to guarantee the correct linear movement of the control element also in the conditions of unbalanced load on the levers of the toggle. In this case it is a solution borrowed from the classic toggle configuration with movement of the levers inwards. At the same time this configuration does not require the control element to be guided on the columns of the toggle, with clear dimensional advantages.

[0066] In particular, as can be seen better in the horizontal sections of FIGS. 5A and 6A, the columns 24 of support and guide of the control element 6 are attached, at their two ends, to the opposite ends 101, 102 of corresponding supports 110 of the reaction plane 1 oriented towards the mobile plane 2.

[0067] This solution allows the maintaining of the levers horizontal and in a position such as to leave the space necessary for the extraction assembly, denoted by reference numeral 15. The control element 6, shown in isolation in FIG. 7, has four seats for guide bushings 21 for the sliding of the respective columns 24, two heads 25 with seat 22 for the pins of connection with the connecting rods 8, and two seats 23 for housing the control pistons 14.

[0068] As an alternative to the guide columns 24 and to the guide bushings 21 a system of guides can be used, constituted by sliding planes with slide shoes, or a system of recirculation guides with ball bearing or roller slide blocks in which the fixed part is integral with the reaction plane 1.

[0069] The particular configuration of the control element 6, of the reaction plane 1 and the position of installation allow high strokes of opening to be created, reducing to a minimum the overall dimension of the toggle.

[0070] FIG. 6 shows the toggle sectioned in the condition of mould completely open.

[0071] The control element 6 conserves the system of guides inside the toggle, typical of the systems with closure of the levers inwards, but brings to the exterior the heads 25 of connection with the connecting rods 8. In this way it is possible to compact the configuration and to make independent the main structure (the three planes and the control element) from the length of the main connecting rods 4, 5.

[0072] This condition allows the possibility of increasing the maximum stroke of opening, changing only the levers 4, 5 of the toggle, without having to intervene on the main structures.

[0073] More particularly, by referring to FIG. 8, the distance between the points A and C of the lever 4 provided with the connection to the connecting rod 8 has to increase proportionally to the increase in the distance between the points D and E of the conjugated lever 5, while the distance between the points A and B of the first lever 4 has to remain unchanged as also the angle a between the straight lines A-B and A-C has to remain unchanged. In practice, therefore, the point C has to move linearly on the straight line A-C as the length of the lever 5 varies.

[0074] The increase in the stroke of opening is proportional to the increase in length of the connecting rods.

[0075] Moreover, in the solution proposed, the control element 6 is not guided on the main columns 16 of the toggle with the relative problems associated with the threads 10 of mould thickness regulation, with the weight and the need to create elements of support for the control element on the bed.

[0076] A further feature of this toggle is the I-shaped structure of the reaction plane 1, as shown in FIGS. 9a and 9b. This structure, possible for a toggle with opening of the levers outwards, optimises the weights of the structure and the features of rigidity of the element.

[0077] As an alternative to the solution with the double piston for the actuation of the control element 6, as shown in FIG. 10, it is possible to use a single central piston, denoted again by reference numeral 14, restrained to the reaction plane 1, whose rod 13 is connected centrally to the control element 6.

[0078] It is also possible to carry out, for the actuation of the control element 6 of the levers, the movement by means of a pair of electric actuators with recirculating screws placed in the position previously occupied by the pair of cylinders 14 (FIGS. 2-6) or by means of a single electric actuator with recirculating screw placed in the position previously occupied by the central cylinder (FIG. 10).

[0079] FIG. 11 gives a representation of the first solution, in which two electrically powered screw actuators 30, driven by direct motors 31, actuate the control element 6 threading in respective screw grommets 32 integral with the control element 6.

[0080] Naturally the invention is not limited to the particular embodiments previously described and illustrated in the accompanying drawings, but numerous detailed changes may be made thereto, within the reach of the person skilled in the art, in any case coming within the scope of the invention as defined by the appended claims.