FR2493955A3 - Retractable guard for press - uses two linked co-planar pivotable shutters which counter-balance one another when deployed or retracted - Google Patents

Abstract

The protective screen is operated manually and is used as a safety shield on a single-action press. It comprises two pivotable shutters (7,8) mounted one above the other in a common plane. The relationship between the shutters and their fulcra (5,6) is such that they are mutually counterbalanced when in the terminal open and closed positions. They have a demountable system of levers (1,2,3) of which the position can be modified. The open position of the shutters is determined by the different arrangements of the levers.

Description

 The invention relates to a manually-operated protective screen or shield intended to be mounted as a universal safety device on mechanical presses working step by step.

We know from the published German patent application
N 2 712 274, a safety device mounted on hydraulic swan neck presses, in which there is provided, for easy actuation of the screen, a tension spring acting as a counterweight, or a balancing weight, the screen to be operated by hand using a handle.

Another publication, namely the Qatats patent
United States of America No. 2,934,129 also mentions a press device, which is protected by a manually-operated protective basket, to the supply of which, in the open position of this basket, contributes the force of a spring.

 In addition, the protective screens available on the market generally work so that after the installation of the part, the closing of the dangerous space by the protective screen takes place electrically, pneumatically or hydraulically after actuation. of contacts.

 The last cited achievements are only intended for a specific press and do not take into account the multiplicity of existing tools, or presses, which, due to the new safety regulations issued by professional bodies for the ordering of mechanical presses, must be retrofitted with a protective screen.

 In addition, closing the hazardous volume after the workpiece has been installed, by electrical, pneumatic or hydraulic means, must be considered costly both technically and in time.

 The said protective screens, or the manually actuable protective bodies must be considered - even if only in principle - as possible retrofitting installations.

 The acceleration of the protective elements in a single piece from the two end positions is costly in time and in energy, despite the help provided by the spring bar and / or the planned counterweight, given that the closing operation can only be triggered after the withdrawal of the inserted hand.

 Due to the aforementioned drawbacks, the aim of the invention is to provide a manually-operated protective screen which, while respecting the existing regulations, allows, with minimum expenditure of energy, wide use of shorter cycles during the pricking of parts which must be put in place by hand.

 The invention provides that the protective screen is constituted by two tilting or pivoting flaps arranged one above the other in the same plane on the side of the user, fixed in their end positions - the open position and the closed position - by the fact that their weights balance each other around their horizontal pivot axes, and by a set of removable levers with several positions connecting the tilting flaps, and that the open end position of the tilting flaps is determined by the different possible arrangements of the set of levers.

 Since the weights of the flaps almost offset each other, the use of a balancing counterweight and / or that of a spring force can be eliminated. The shutters can easily be closed and opened by hand, after unlocking. The closing movement is carried out, after placing the part in the press and removing the inserted hand, with the same hand and in the same plane of movement.

 Since the movement is almost entirely conditioned by reflexes, the protective screen can be closed in a very short time, locked in a fraction of a second and the press can be triggered automatically.

 noting given that with known protective screens with manual control, the hand must be practically withdrawn in "dead time", before closing the screen with the same hand can be effected by a separate movement, it results, compared to known embodiments, a reduction in cycle times of almost 100%.

 The possibility of determining the terminal or green position by a simple change of position of the set of levers, allows an optimal adaptation to the tool used each time and to the part to be put in place.

 The division in two of the screen allows to intervene at working height.

The invention will be clearly understood on reading the detailed description, given below by way of example only, of an embodiment shown diagrammatically in the drawing, in which
fig. 1 to 4 show, in diagrammatic view, possible positions of the two flaps 7 and 8 which are mounted around horizontal shafts 4 and 5 in the support 5 with bearings.

 The interchangeable position linkage 1 is constituted by the two levers 2 connected by the shafts 4 and 5 and by the connecting bar 3.

 Depending on the desired position of the flaps 7 and 6, the points of articulation of the connecting bar 3 are changed.

Claims (1)

 CLAIM  Manually operated protective screen intended to be mounted as a universal safety device on mechanical presses working step by step, characterized in that the protective screen consists of two tilting flaps (7 and 8) arranged one above on the other in the same plane, on the side of the user, held in their end positions (the open position and the closed position) by the fact that their weights mutually balance around their respective horizontal pivot axes, and by a set of levers (and 3) removable in several positions connecting the tilting flaps, and in that the open end position of the tilting flaps (7 and 8) is determined by the different possible arrangements of the set of levers (2 and 3).