ES2356583T3 - PUNCHING MACHINE. - Google Patents

Abstract

A punching machine for sheet metal strip, characterised by comprising: -a base (2), -a horizontal first plate (6) movable vertically under external command, -a punch (20) rigid with saidfirst plate (6) and slidable within a punch guide (18) rigid with a horizontal second plate (16), -means (12, 14) for slidably constraining said second plate (16) relative to said first plate (6), -first elastic means (36) interposed between said first plate (6) and said second plate (16), -a horizontal third plate (24) housed in a seat provided in the base (2), -means (22) enabling said third plate (24) to be moved vertically by said first plate (6), -second elastic means (38) interposed between the lower surface of said third plate (24) and the bottom of the seat (26), said second means having a greater constant of elastic rigidity than the first elastic means, -a die (28) rigid with the base (2) and facing the punch guide (18), -a counter-punch (30) slidable within said die (18), rigid with said movable third plate (24), said die (18) being provided internally with an air jet feed channel (32) and a scrap discharge channel (34), these communicating with the seat of the counter-punch (30), the punchhead (40) having a diameter less than the diameter of its seat in the punch guide (18), said seat being of smaller diameter than the counter-punch (30), the counter-punch (30) being provided at that end facing the punch (20) with a frusto-conical portion (46), the major base of which has a diameter less than the diameter of the punch seat and the minor base of which has a diameter greater than the diameter of the punch head (40).

Description

The present invention relates to a punching machine (see for example JP-A-11 31 9990).

The object of the invention is to provide a punching machine that also rounds the edge of the hole formed by the punch. 5

This objective is achieved according to the invention by means of a punching machine for a sheet metal strip as described in claim 1.

A preferred embodiment of the present invention will become more clearly apparent by reference to the accompanying drawings, in which:

Figure 1 is a longitudinal section through a punching machine according to the invention, 10

Figures 2, 3, 4, 5 and 6 show said machine in several stages of operation, and

Figure 7 is a detailed view of the punching head.

As can be seen in the figures, the punching machine according to the invention substantially comprises a base 2 provided with columns 4 for guiding an upper horizontal plate 6 that can be operated vertically by means of a piston 8. 15

The plate 6 is provided with a seat 10 to accommodate the heads 12 of threaded bolts 14 that are coupled at its lower end in a second plate 16 that supports a punch guide 18 into which a rigidly fixed punch 20 slides inside with plate 6.

The plate 16 is guided along the columns 4 and, in addition, along some columns 22 provided at the bottom of a plate 24 housed in a seat 26 provided in the base 2. 20

The plate 24 is provided on its upper part with a die 28, inside which a rigidly fixed tailstock slides with the plate 2. The die is provided inside with two channels 32, 34 to feed an air jet and download the leftovers respectively.

A pair of springs 36 are interposed between the plate 6 and the plate 16, with a pair of springs 38 interposed between the bottom of the seat 26 and the bottom surface of the plate 24. 25

The springs 36 have a lower stiffness than that of the springs 38.

The head 40 of the punch 20 has dimensions smaller than those of its rod 42 (whose diameter is smaller than the diameter of the tailstock 30) and is connected thereto by a conical portion 44.

The upper surface of the tailstock is provided with a frustoconical portion 46, whose outer diameter is greater than the diameter of the head 40 of the punch 20, but smaller than the diameter of the shank rod 42. 30

The machine according to the invention operates as follows.

When not in operation, the plate 6 is in the maximum distance configuration with respect to the plate 2, the springs 36 and 38 keeping said plate 6 with the plate 16 and the plate 24 with the base 2, in the configuration of the greatest separation distance (see figure 1). The punch 20 is fully inserted in the punch guide 18. 35

The metal sheet 48 is advanced, so that it is arranged in the mold 28, after which the piston 8 is operated to lower the plate 6 and, thus, the plate 16 (by means of the springs 36) until the guide for punch 18 rests on mold 28 to retain the sheet metal (see Figure 2).

The subsequent descent of the plate 2 has the following effect (see Figure 3):

- the punch exit of the punch guide, 40

- the start of the punching stage by the punching head,

- lowering the plate 24 towards the seat 26.

As the descent of the plate 24 continues, the initial effect (Figure 4) is as follows:

- the additional descent of the plate 24,

- the complete punching of the sheet metal, 45

- compression of springs 36 and 38,

followed by (see figure 5):

- the fall of the leftovers of the punching,

- its expulsion along the channel 34 by the programmed air jet,

- 90 ° beading of the profiled edge in the hole thanks to the mutual interaction between the mold 28 and the punch guide 18.

At this point, the plate 2 is raised by the piston 8, resulting in (see Figure 6):

- the elevation of the punch 20 along the punch guide, which is always in contact with the mold 28 thanks to the elastic reaction of the spring 38, which is greater than the elastic reaction of the spring 36,

- the interaction between the truncated conical part 46 of the tailstock 30 and the flared edge of the metal plate 10 to bend it in a U-shape against the punch guide 18.

Claims (5)

1. Punching machine for sheet metal band comprising: - a base (2), - a first horizontal plate (6) that can be moved vertically according to an external order, 5 - a punch (20) rigidly fixed to said first plate (6) and that can slide in a guide for punch (18) rigidly fixed with a second horizontal plate (16), - means (12, 14) for limiting the sliding of said second plate (16) with respect to said first plate (6), - first elastic means (36) interposed between said first plate (6) and said second plate 10 (16), - a third horizontal plate (24) housed in a seat provided at the base (2), - means (22) that allow said third plate (24) to move vertically by means of said first plate (6), - second elastic means (38) interposed between the lower surface of said third plate (24) and 15 the lower part of the seat (26), said second means presenting a constant of elastic stiffness greater than the first elastic means, - a mold (28) rigidly fixed with the base (2) and facing the punch guide (18), - a tailstock (30) that can slide in said mold (28), rigidly fixed with said third movable plate (24), 20  said mold (28) being provided in its inner part with an air jet feed channel (32) and an excess evacuation channel (34), said channels communicating with the tailstock seat (30),  said punching head (40) having a diameter smaller than the diameter of its seat in the punch guide (18), said seat presenting a diameter smaller than the counterpoint (30), said counterpoint (30) being provided at said end facing the punch (20) of a truncated conical part (46) whose major base has a diameter smaller than the diameter of the punching seat and whose smaller base has a diameter greater than the diameter of the punching head (40). 2. Machine according to claim 1, characterized in that the horizontal plate can be moved, driven by a hydraulic cylinder and piston unit (8). 3. Machine according to claim 1, characterized in that the base (2) is provided with columns (4) for guiding the second and third plates. Machine according to claim 1, characterized in that the means for limiting the sliding consist of bolts (14) that at one end are coupled with the second plate and whose head (12) is housed in a seat provided in the first plate . Machine according to claim 1, characterized in that the means that allow movement (22) 35 consist of a punch (20).