FR2550125A1 - Machine for cutting out cellular plastic blocks. - Google Patents

Abstract

This machine comprises heating wires associated with two drums over which they are partially wound. The wires 1, 2, etc., are wound alternately from one to the other, in directions opposite to each other, over the two drums 3, 4 and these two drums 3, 4 are associated with two detour (deflection) rollers 9, 10 over which the wires pass respectively before their entry at and after their exit from the two drums, thereby forming a plane sheet of superposed parallel wires set alternately, one with respect to the other, into a reverse to-and-fro movement.

Description

CUTTING MACHINE
BLOCKS OF ALVEOLAR PLASTIC MATERIAL
The invention relates to a machine for cutting blocks of cellular plastic.

 To cut blocks of cellular plastic material into sheets or mattresses, there are machines essentially consisting of a fixed frame on which are heated metal wires. Cutting is efficient, but requires high electrical power, and the flatness of the cuts is random.

 To overcome these defects, there are machines comprising two consecutive wire-carrying frames moving back and forth in the opposite direction; the quality of the cut is correct, but the energy required to set the frames in motion is very important and the movement of the frames generates significant vibrations.

 There are also machines in which the active elements are constituted by metallic heating wires, the ends of which are linked to two drums of parallel axes and driven in oscillating movements in the opposite direction. These machines are efficient, but costly in energy to band the springs; the stroke of the wires is necessarily very small on the order of 5 mm, and the fatigue of the springs is great, which leads to their rapid destruction. There is therefore no machine allowing quality cuts, in a durable, economical and convenient way.

 The invention remedies this shortcoming. It relates to a machine which is of the type of those comprising heating wires associated with two drums; but in this machine the wires are wound alternately from one to the other in opposite directions from one another on the two drums, and these two drums are associated with two detour rollers over which the wires pass respectively before their entry and after their exit from the two drums, by forming a flat sheet of superimposed parallel wires alternately animated with respect to each other in a back-and-forth movement.

 The assembly formed by the two drums and the two detour rollers is carried by a frame secured to a frame equipped with a movable table on which is placed the block of plastic material, one of the front faces of which thus comes into contact. with the wires for cutting the block into plates.

 According to the invention, this frame has, moreover, an important characteristic, according to which it is articulated on its support around a transverse axis parallel to the heating wires, means being provided for immobilizing this frame, either in a perpendicular position. at the table, either in a more or less inclined position relative to the table, the vertical position determining the maximum thickness of the plates for a determined spacing of the wires on the drums, and the inclined positions determining decreasing thicknesses as and when measure that increases the inclination of the frame relative to the vertical.

 According to an advantageous embodiment of this machine, this axis of articulation of the frame coincides moreover with the lower wire of the layer of heating wires, which makes it possible to always keep the same position with this lower wire and so on. in all cases, obtain an equal thickness for the lower plate cut from the block, which is considered to be lost because it is cut from the underside of the block and therefore always has defects.

 The dimensions of the two wire winding drums and their spacing can be arbitrary, which makes it possible to envisage the cutting of blocks of all dimensions, impurient wire strokes and high oscillation frequencies. The power consumed is limited to that allowing, by driving the drums, to move the wires in contact with the plastic block.

The invention will be well understood moreover and its advantages as well as other characteristics will emerge clearly from the description which follows with reference to the appended schematic drawing representing, by way of nonlimiting example, an embodiment of this machine for cutting plastic blocks for the production of plates
Figure 1 is a general and very schematic view showing the essential elements of this machine;
Figure 2 is a partial elevational view of one of the two detour rollers fitted to this machine;
Figures 3 and 4 are schematic side elevational views illustrating the active assembly of the machine, that is to say the assembly carrying the cutting members of the plastic block, this assembly being shown in two positions allowing obtaining plates whose thicknesses are different in one and in the other position.

 FIG. 1 illustrates the essential organs of the machine, organs whose role is to cut horizontally a block of plastic material into superimposed plates; and if in the case represented in FIG. 1 the number of the heating wires is only two, this limitation to two wires is made voluntarily to simplify the drawing; but it is obvious that in reality the number of these wires is much higher in order to allow the cutting from the same block of plastic material of a plurality of superimposed plates.

 In FIG. 1, (1) and (2) denote two metallic heating wires whose two ends, respectively (la, lb) and (2a, 2b) are fixed on the periphery of two cylindrical drums (3) and (4) whose axes are parallel; and it is important to note that these two wires (1) and (2) are each fixed inversely to each other on each of the two drums (3) and (4). I1 is also to note that the two drums (3) and (4) are animated with oscillating movements in opposite directions to each other. It follows that when the drum (3) rotates for example. in the direction of the arrow (5) of Figure 1, the drum (4) rotates in the opposite direction along the arrow (6), the wire (I) moves in the direction of the arrow (7), and. wire (2) moves in the opposite direction according to arrow (8).

 In front of the two drums (3) and (4) are placed two detour rollers respectively (9) and (10) over which the wires (1) and (2) pass during their journey between the drums (3) and ( 4). In the area between the two detour rollers (9) and (10), the wires (1) and (2) constitute in combination with all the other wires linked to the drums (3) and (4) a layer of wires, ply in which the threads are superimposed parallel to each other with a determined spacing and are animated from one to the other in a reverse movement with respect to each other.

 Means are of course provided to allow the ends of the wires (1) and (2) to be fixed in an effective but adjustable manner on the drums (3) and (4); and as shown in Figure 2, peripheral grooves (12) are arranged on cylindrical rings (13) that includes the detour roller (10). Thanks to these grooves (12), the wires (1) and (2) are perfectly positioned on the detour rollers (9) and (10) and the spacing between the wires (1) and (2) is itself determined in a stable manner, thus making it possible to obtain plates of strictly constant thickness by cutting out from the plastic block.

Means may however be provided to allow the rings (13) constituting shoulders on the detour rollers (9) and (10) to be able to be positioned in an adjustable manner on the rollers (9) and (10) in order to allow adjustment. very precise spacing between the grooves of the rings and therefore very precise adjustment of the spacing of the wires (1) and (2).

 The assembly constituted by the drums (3) and (4) and by the detour rollers (9) and (10) as well as by the axes supporting them is mounted on lateral supports which are articulated around a transverse horizontal axis (14) on a frame not shown in the drawing. This axis (14) coincides with the lower wire (2) of the web of wires used for cutting the block of plastic material into plates.

 As for the means used to give alternative rotational movements to the two drums (3) and (4), they can be any; and this is how, in the case shown in the drawing, use is made of a geared motor group (15) whose axis (17) drives, by means of a pulley (18) and a belt ( 19), a second pulley (21) wedged on a transverse shaft (22). This shaft (22) which is driven by a continuous rotational movement gives the shafts (23) and (24) of the two drums (3) and (4) reciprocating rotational movements by means of oscillator mechanisms generally designated by (25).

 As is known per se, the cutting of the block of plastic material into plates is obtained by advancing these blocks in the direction of the heating wires (1) and (2) and this by means of a movable table (26) [Figures 3 and 4 ] on which the block (27) was previously placed.

When it moves in the direction of the arrow (28) in FIGS. 3 and 4, the table (26) brings the block (27) into contact with the heating wires (1, 2, etc.), which makes it possible to obtain the cutting of the block into superimposed plates.

 If as shown in Figure 3 the lateral supports of the drums (3) and (4) and the detour rollers (9) and (10) are in the vertical position and if the spacing between the wires (1, 2 ... ) is constant from one wire to another, all the plates (29) cut from the block (27) have an equal thickness.

 However, it is possible and this is an advantageous characteristic of the machine which is the subject of the invention to obtain plates of adjustable thickness at will, while maintaining the same spacing between the wires (1, 2. .). For this, it suffices to tilt the lateral supports of the drums (3) and (4) and of the detour rollers (9) and (10) so that, as shown in FIG. 4, the active assembly of the machine is inclined and thus the thickness of the plates (29) cut from the block (27) becomes smaller. The more the lateral supports of the drums (3) and (4) and the detour rollers (9) and (10) are inclined, the more the thickness of the plates (29) cut from the block (27) will be reduced.

 It should however be observed that even when the thickness of the plates (29) is reduced, that is to say when the active assembly occupies an inclined position, the lower plate cut out from the block (27) retains the thickness it would have if this assembly were in vertical position. This is due to the fact that the axis (14) around which the active assembly is articulated coincides with the lower wire (2) of the layer of wires.

 It goes without saying that the invention is not limited to the sole embodiment of this machine for cutting blocks of plastic which has been indicated above by way of example; on the contrary, it embraces all of its variant embodiments.

Claims (3)

 1. - Machine for cutting blocks of cellular plastic material, comprising heating wires associated with two drums on which they are partially wound, characterized in that the wires (1, 2 ...) are wound alternately from the 'to each other in opposite directions to each other on the two drums (3, 4), and these two drums (3, 4) are associated with two detour rollers (9, 10) on which the son pass respectively before their entry and after their exit from the two drums, forming a flat sheet of superimposed parallel son alternately animated with respect to each other in a back and forth movement.  2. - Machine for cutting blocks of cellular plastic material according to claim 1, characterized in that the frame serving as support for the two drums (3, 4) and the two detour rollers (9, 10) is articulated on its support around a transverse axis (14) parallel to the heating wires (1, 2 ...), means being provided for immobilizing this frame either in a position perpendicular to the table, or in a position more or less inclined relative to at the table, the vertical position determining the maximum thickness of the plates for a determined spacing of the wires on the drums, and the inclined positions determining decreasing thicknesses as the inclination of the frame increases.  3. - Machine for cutting blocks of cellular plastic material according to claims 1 and 2, characterized in that the axis (14) of articulation of the frame carrying the two drums (3, 4) and the two detour rollers (9, 10) coincides with the lower wire (2) of the heating wire layer (1, 2 ...)