FR2692834A1 - Continuous deadening of polyurethane foam blocks - by crushing the block between two independently driven compression rollers - Google Patents

Abstract

A method of continuously deadening polyurethane or similar foams by breaking up the larger cells of the foam blocks skin consists of (a) rotating two compression rollers (5,6) with linear tangential speed close the linear speed of the foam block (16); (b) symmetrically moving the rollers (5,6) together to crush the foam (16) between them. Also claimed is a machine with a frame (1) supporting two independently driven compression rollers (5,6) each movable w.r.t the frame. The machine for a block conveying system (2). USE/ADVANTAGE - Continuous deadening of polyurethane or similar foam blocks. Allows direct in-line deadening of foam blocks in prodn.

Description

Method and device ~ a2 to continuously denote a block of polyurethane foam
The invention relates to a method and a device for continuously denervating a block of polyurethane foam.

 During the continuous manufacture of polyurethane foam, a skin comprising coarse cells is formed on either side of the block.

 To obtain a block of polyurethane foam comprising homogeneous characteristics, it is necessary to break the coarse cells of this skin: this operation called "denervation" by specialists results for example from a mechanical crushing of these skins.

 The object of the invention is to allow efficient and continuous denervation of polyurethane foam blocks, so as to denerve directly within the production line, increasing the reliability and productivity of the production of polyurethane foam. .

The subject of the invention is a process for continuously denervating polyurethane foam or similar plastic material comprising the following steps
- rotate the crushing rollers so that their linear tangential speeds are close to the linear speed of the foam block
- move the rollers symmetrically, bringing them together so as to crush the foam block between the rollers.

According to other features of the invention
- the linear tangential speed of one roller does not differ by more than thirty percent from the tangential speed of another roller;
- The rollers are removed beforehand so as to allow the introduction of the foam block;
- The crushing rollers are kept in rotation and in a close position during the passage of the foam block;
- It includes a frame supporting crushing rollers, means for moving said rollers and a device for continuously transferring the foam block
- The frame supports means for driving the crushing rollers in rotation;
the displacement means move the rollers apart or bring them closer while keeping them substantially symmetrical with respect to a plane;
- The displacement means are shaped to bring the rollers closer or further apart according to an adjustable displacement speed of between 0 and 15 meters per minute;
each crushing roller is driven by an independent means, the speed of which is adjustable so as to drive said roller at a linear tangential speed of between 0 and 40 meters per minute;
- the frame has four columns on which cross sleepers supporting the crushing rollers and their rotation drive means
The invention will be better understood thanks to the description which follows given by way of nonlimiting example with regard to the appended drawings in which
Figure I shows a partial schematic view in front elevation of a device according to the invention;
2 shows a partial schematic view in side elevation in the direction of arrow II in Figure 1, of a device according to the invention.

 Referring to Figures 1 and 2, a device according to the invention comprises a frame 1 and a conveyor 2 symbolized by its rollers 2a at 2h.

 The frame 1 comprises at least two columns 3, 4 positioned on either side of the conveyor 2.

Columns 3 and 4 support two rollers 5 and 6 driven in rotation by respective geared motor groups 5a and 6a
The speed of each geared motor group 5a, 6a is adjustable within a speed range between 0 and 20 revolutions per minute, so as to drive each respective roller at a linear tangential speed between 0 and 40 meters per minute .

The spacing of the rollers or cylinders 5 and 6 is preferably infinitely adjustable by means comprising for example
a motor 7 located on a beam S connecting columns 3 and 4 transmitting a movement of at least one bevel gear 9 symbolized by two concurrent axis lines,
at least one square or trapezoidal thread screw symbolized by the axis 10 driven by the bevel gear 9 and mounted for rotation in two bearings 11, 12 situated at the opposite ends of the column 3 or 4.

 at least two blocks 13, 14 simultaneously forming support bearings for the respective rollers 5 and 6 and drive nuts cooperating with the drive screw 10.

 The directions of the corresponding threads of the nuts 13, 14 and of the screw 10 are predetermined so that the rollers 5 and 6 are substantially symmetrical with respect to the median work plane 15 symbolized by the corresponding axis lines in FIGS. 1 and 2: the nuts 13, 14 have for example an identical thread and the screw 10 then consists of two integral half-screws having threads in opposite directions to one another, or vice versa.

 Preferably, the speed of spreading or bringing together the rollers or cylinders 5 and 6 according to a substantially symmetrical movement relative to the fixed plane 15 is adjustable and between 0 and 15 meters per minute.

 Advantageously, the device according to the invention comprises four columns 3a, 3b; 4a, 4b supporting blocks 13, 14 constituted in this case by four movable crosspieces moving by a screw-nut system or the like according to parallel and symmetrical displacements relative to the plane 15.

According to the invention, the process for denervating polyurethane comprises the following steps
1 / Move aside the crushing rollers 5, 6 so as to allow the introduction of a block 16 of polyurethane foam circulating in a predetermined direction indicated by the arrow A.

 This spacing position is marked in solid lines in FIG. 1 and in broken lines in FIG. 2.

 2 / Rotate the rollers 5 and 6 so that their respective linear tangential speed does not differ from each other by more than thirty percent and is close to the linear speed of the foam block.

 3 / Move the rotating rollers 5 and 6 symmetrically with respect to the plane 15 so as to bring them closer to one another by crushing the block 16 of polyurethane foam circulating between the rollers 5 and 6.

 4 / Keep the rollers in rotation in the close position for the time corresponding to the passage of block 16.

 5 / After passage of the block, move the rollers 5 and 6 away in the direction of the arrows D in Figure 2 and immobilize them in rotation.

 The close position of the rollers 5 and 6 is shown in solid lines in FIG. 2 and in broken lines in FIG. 1.

In order not to subject the frame 1 to excessive forces while ensuring effective denervating, the approximation of the rollers 5 and 6 is limited to a distance greater than one third of the thickness of the block of polyurethane foam to be denervated
Thanks to the invention, foam blocks are continuously deviated having in particular the following dimensions
width: 2.4 m
. height: 1.5 m
length: several hundred meters
The respective diameters of the rollers 5 and 6 are preferably greater than half the average thickness of the foam blocks to be denerved: this arrangement allows direct entry of the foam block 16 by avoiding the prior separation of the rollers 5 and 6 and Thus increases both the productivity and the ease of implementation of the invention.

Claims (10)

Claims  1. Process for continuously denervating polyurethane foam or similar plastic material comprising the following steps  - rotating the crushing rollers (5, 6) so that their tangential linear speeds are close to the linear speed of the foam block (16)  - move the rollers (5, 6) symmetrically, bringing them together so as to crush the foam block (16) between the rollers (5, 6).  2. Method according to claim 1, characterized in that the linear tangential speed of a roller (5 or 6) does not differ by more than thirty percent from the tangential speed of another roller (6 or 5).  3. Method according to claim 1 or 2, characterized in that the rollers (5, 6) are removed beforehand so as to allow the introduction of the foam block (16).  4. Method according to any one of claims 1 to 3, characterized in that the crushing rollers (5, 6) are kept in rotation and in close position during the passage of the foam block (16).  5. Device for continuously denervating plastic foam blocks such as polyurethane, characterized in that it comprises a frame (1) supporting crushing rollers (5, 6), displacement means (7- 14) of said rollers (5, 6) and a device (2) for continuously transferring the foam block (16).  6. Device according to claim 5, characterized in that the frame supports means (5a, 6a) for driving in rotation the crushing rollers (5, 6).  7. Device according to claim 5 or claim 6, characterized in that the displacement means (7-14) distance or bring the rollers (5, 6) apart while keeping them substantially symmetrical with respect to a plane (15).  8. Device according to claim 7, characterized in that the displacement means (7-14) are shaped to bring the rollers (5, 6) closer or further apart according to an adjustable displacement speed between 0 and 15 meters per minute.  9. Device according to claim 6, characterized in that each crushing roller (5 or 6) -is driven by an independent means (5a or 6a), the speed of which is adjustable so as to drive said roller (5 or 6 ) at a linear tangential speed between 0 and 40 meters per minute.  10. Device according to any one of claims 5 to 9, characterized in that the frame (1) has four columns (3a, 3b; 4a, 4b) on which cross sleepers (13, 14) supporting the rollers d 'crushing (5, 6) and their rotational drive means (5a, 6a).