The invention relates to a sheet-metal bending machine.
In particular, the machine is best applied in the bending of metal sheets of differing thicknesses, of satin-finish stainless steel, or prepainted sheets, or plasticated sheets and so on, which are destined for widely differing uses, such as, for example , in the construction of metallic furniture, the cases of household electrical appliances, shelves, etc., in which the bending zones of the sheet, the paint or the protective layer must be without defects.
The prior art embraces sheet-metal bending machines of different types able to avoid the formation of defects in the bending zone.
Said machines comprise a fixed supporting structure having two pressing elements: one fixed lower element, on which the sheet to be bent is placed, and one mobile upper element, which keeps the sheet pressed on to the lower element. A mobile frame, having a substantially c-shaped transversal section, is associated with the fixed element, which frame has two blades, one upper and one lower, which blades, following the raising or lowering of the mobile frame effect the bending of the sheet.
To avoid the formation of defects in the bending zone, and in order to be able to carry out bendings with different angles as well as roundings of the said bending angles, a movement of the mobile frame is envisaged, both away from and towards the sheet to be bent.
The prior art embraces a first type of machine in which said movement is realised by means of the use of manual adjustment systems. The well-known drawback of these machines is constituted by the fact that correct execution of the bending depends largely on the operator's ability.
The prior art embraces also a second type of machine, in which the bending blade's movement away from and towards the sheet is executed envisaging that the blades should be moved singly. That, as is well known, considerably complicates the machine from the point of view of construction. The machine also becomes extremely complex and expensive and difficult to control in that there are two movement directions to manage (one for each bending blade).
The prior art also embraces a third type, in which the movement towards and away from the blade is made by the entire mobile frame. The movement system in this case is constituted by hydraulic cylinders. The well-known drawback of such machines is that the hydraulic cylinders cannot carry out micrometric movements with great accuracy. In practice, therefore, the positioning of the mobile frame carrying the two blades is insufficiently precise and furthermore is difficult to manage.
In a fourth type of known machine, such as the object of US 4,722,214 the movement system of the entire mobile group away from and towards the metal sheet is realised in the following way.
The mobile group (having a c-shaped section) is provided with a pair of plate-shaped arms, hinged to the fixed support structure of the machine. A cam organ is positioned at the articulations of each of the two plate-shaped arms, which cam organ is set in rotation by a jack, by means of a lever.
The principal aim of the present invention is therefore that of overcoming the above-cited drawbacks relative to prior art machines, and of providing a sheet-metal bending machine capable of operating on sheets of different thicknesses, avoiding the formation of defects in the bending zones, and of realising bending angles with the possibility of rounding them: said machine is extremely simple from the point of view of construction, extremely precise, reliable and easy to manage from the operative point of view, and can be operated automatically.
This aim and others besides are all achieved by the machine of the invention, essentially comprising a fixed support structure bearing a lower pressing element on which the sheet to be bent is rested, and to which is associated an upper mobile pressing element, which press the sheet against the lower pressing element, said upper press element being borne by a mobile structure, the machine further comprising a mobile frame, borne by the said support structure, having a transversal section which is substantially c-shaped and which bears an upper blade and a lower blade, the said blades performing the bending of the metal sheet when the mobile frame is raised or lowered, hydraulic jacks being provided to perform the raising or lowering of the mobile group, the said mobile frame further being able to translate from and towards the metal sheet by means of an activation system formed by a cam organ to which a connection means is associated, which connection means is interpositioned between the said cam organ and the said mobile frame, characterised in that the said cam organ is constituted by a plurality of cam devices in line among themselves and positioned along a shaft, which shaft extends over the entire length of the mobile frame, the said shaft being able to perform rotation in both directions with rotation degrees determined by prefixed operative phases.
Further characteristics and advantages of the invention will better emerge from the detailed description which follows, of a preferred but not exclusive embodiment herein illustrated purely in the form of a non-limiting example in the drawings, in which:
The upper pressing element 5 is borne by a mobile structure, hinged 7 to the support structure 1, which support structure 1 is able to perform vertical-plane oscillations by the activating of at least one double-acting hydraulic cylinder 8 which is fixed respectively to the mobile structure 6 and to the support structure 1.
Inside the chamber 2 a mobile frame 9 is housed, having a substantially c-shaped transversal section, and bearing an upper blade 10 and a lower blade 11.
The blades 10 and 11 effect the bending of the sheet 4 when the mobile frame 9 is raised or lowered: the blade 10 or the blade 11 interferes with the sheet 4 in proximity to the zone where it exits from the pressing elements 3 and 5, effecting thus the bending: the upper blade 10 effects the downwards bending, while the lower blade 11 performs the upwards bending.
The raising and lowering of the mobile frame 9 is performed by at least one double-acting hydraulic cylinder 12 constrained to the mobile frame 9 and to the support structure 1.
The mobile frame 9, which is pivoted on a shaft 13 positioned in the posterior part of the support structure 1, is also able to slide horizontally away from and towards the sheet 4 by means of a particular activating system. Said activating system comprises at least one cam device 14, formed by a plate element 15 splined on the shaft 13, to which shaft 13 a connecting element 16 to the mobile frame 9 is solidly fixed.
The mobile frame 9 is thus pivoted on the shaft 13 by the cam device 14.
The shaft 13, activated by known means, is able to perform rotations in both directions with excursions determined by pre-established operative phases for example, 100° in one direction and 100° in the opposite direction) controlled by a computer (not in the figures).
Said computer furthermore manages all the other movements of the machine, permitting of a programmable funtioning, according to the operative requirements , which is completely automatic.
In figures 3, 4, 5,and 6 four phases of bending of the sheet 4 are illustrated by way of example.
In fig. 3 the moment of positioning of the blade 11 in relation to the sheet 4 is represented.
In fig.4 the vertical activating of the blade 11 is represented, bringing about the formation of a bend greater than 90°.
In fig. 5 the horizontal activating of the blade 11 is represented (produced by the rotation of the shaft 13 and consequently of the cam device 14) bringing about the formation of a bend with a 90° angle.
In fig. 6 a further horizontal displacement of the blade 11 is represented , bringing about the formation of a bend with an angle of less than 90°.
It is notable that from the point of view of construction and functioning the present machine is very simple, and as a result of this will be very economical to run, and will cause few operative problems.
The invention therefore attains the pre-established aims.