Method and apparatus for making foam blocks of bonded foam pieces

The invention relates to a method and an apparatus for the production of foam blocks in composite flock.

For the production of composite foam is on flake size shredded polyurethane foam with a binder such as a polyurethane prepolymer mixed in a filled molding box and compacted to the desired density or slab height. In the polyurethane prepolymer remaining free isocyanate groups react z. B. with moisture from the environment and form urea compounds. To accelerate the reaction can also be saturated steam is passed through the bottom of the mold box and through the foam block will. By this measure, the residence time of the foam blocks in the molding box, the so-called molding time can be considerably shortened.

The flasks usually used have a round or a rectangular cross section , which is constant over the height of the mold box.

When entry of the foam flakes into the molding box, the foam flakes are usually manually or with a suitable device uniformly over the cross-section of the Molding box distributed to differences in density in the horizontal direction in the finished foam block to avoid.

Due to the dead weight of the foam flakes and the low compressive strength of from However, foam flakes formed bed, there is a significant density difference in the bed in the vertical direction. The bed has therefore clearly in the lower region higher density than in the upper region.

This results in that the finished foam block obtained after pressing in the lower region having a higher density than in the upper region. This undesirable effect gets more noticeable the higher the molding box and thus the foam block and The lower the density of the finished foam block.

The object of the present invention to provide a method and an apparatus to provide for the production of foam blocks in composite flock available at the obtained foam blocks with substantially homogeneous density distribution in the vertical direction can be.

The invention relates to a method for the production of foam blocks in the composite flakes in an apparatus comprising a molding box standing with a floor and several on contiguous form side walls and a movable toward the bottom Stamp, wherein at least one of the mold side walls to a substantially held at the bottom horizontal pivot axis between an outward-facing position and a is pivotable substantially vertical position, in which<sl><li>(A) mixing the foam flakes with a binder and</li><li>(B) prior to filling the plastic foam flocks in the molding box at least one of the mold side walls is pivoted to the outside, that the cross-sectional area of ​​the mold box extends from the bottom up, and</li><li>(C) the foam flocks are introduced into the molding box, and then</li><li>(D) the at least one mold side wall is adjusted so that the cross-sectional area of ​​the Mold box above the height is substantially constant, and</li><li>(E) the foam flocks or subsequently by means of the stamp to the desired density Foam block height compressed and the foam particles connected to each other while be and</li><li>(F) is removed from the mold, the finished foam block thereafter.</li></sl>

The mixing of the foam flakes with the binder may, for example, by Spraying the foam flakes with the binder done. be it as binders Polyurethane prepolymers, adhesive or other suitable binder used. To be Favoured Prepolymers of a polyol, preferably a polyether polyol and an isocyanate, preferably toluene diisocyanate and / or Methylendiphenyldiisocyant used.

The invention is based thereon, that the cross section of the molding box during the filling of the plastic foam flocks is extended upwards to the account of the dead weight of the foam flakes occurring density difference in the bed by different supercharging compensate for the different heights of the bed.

According to the invention this is achieved in that one or more mold side walls before filling the foam flocks are inclined by tilting. The side walls of the mold box can rotatably mounted for this purpose at the bottom of the connection point to the ground will.

The mold sidewalls to before filling the foam flakes preferably as far swung out that the foam flakes after filling and after pivoting back the form side walls in the upright position at all altitudes roughly as strong are as compacted in the lower region of the molding box due to the self weight of the bed. The appropriate width to the pivoting movement, that is the appropriate tilt or Swivel angle of the mold side walls must be determined by simple tests.

Aim of optimizing the width of the pivoting movement is generally always a homogeneous adjust density distribution in the finished foam block. Since the foam flocks in but bed are limited flowable, the pressing force is not distributed during pressing always evenly in all directions. Therefore, despite originally homogeneous density distribution in the bed during the pressing to the unequal distribution of the density in the vertical Direction in the finished foam block come. This effect should be considered when selecting the appropriate Tilt or swivel angle as possible taken into account, for example, by preliminary tests the flask is filled with various tilt or swivel angles that form sidewalls are then pivoted back into the vertical position, the bed then pressed and the distribution of density is then examined in the finished foam block.

Usually, the tilting or pivotal angle is in the range of between 0.5 and 30 °, preferably 1 to 20 ° and particularly preferably between 2 and 10 °.

Broadly speaking with the inventive method, however, also targeted any Setting the profiles of density over the height of the finished foam block.

In a preferred embodiment of the method according to the invention, in the apparatus the at least one mold side wall into at least two superimposed sub-segments divided, each of said sub-segments about a substantially horizontal pivot axis pivotally, and the lowermost part of the segment between an outwardly directed position and a pivotally substantially vertical position and wherein the remaining subsegments between an outwardly directed position and a vertical position pivotally. Before pouring the foam flakes then all subsegments are pivoted outwardly, that the cross-sectional area of ​​the molding box from the bottom upwards extended, and all sub-segments are inclined at different angles to the horizontal.

In this way it can be achieved that also the filling level non-linear density gradient after pivoting the side members can be compensated in the vertical.

In a further preferred embodiment of the method is to Device the floor of at least two horizontally movable against each other, preferably at least partially interlocking, ground elements. Before pouring the foam flakes into the molding box, the floor members are moved apart, so that the cross-sectional area soil expands. After filling the plastic foam flocks in the mold box the floor elements are then brought together again.

In this way, the overall height of the entire press apparatus can be minimized.

The invention further relates to a device for producing foam in blocks Flake composite comprising a molding box standing with a floor and several on contiguous form side walls and a movable towards the bottom punch, characterized in that at least one of the mold sidewalls to a held on the ground substantially horizontal Pivot axis between an outward-pointing position and a substantially vertical Position is pivotal.

The substantially horizontal pivot axis is preferably horizontal. The substantially vertical position is preferably perpendicular. but according to the invention are also devices comprising in which the pivot axis or the vertical position easily, for example, a Angle of up to 20 °, preferably at an angle of less than 10 °, from the horizontal or normal deviates.

The mold box preferably has a round, oval or rectangular cross section. Other but cross-sectional shapes are also possible.

In a preferred embodiment, the pivotable mold side walls by means of a Hydraulic device pivotally.

In a preferred embodiment, the pivotable mold sidewalls are in at least divided two superimposed sub-segments, each of said sub-segments in a is substantially horizontal pivot axis, wherein the lowermost part segment between an outwardly facing position and a substantially vertical position pivotally and wherein the remaining sub-segments between an outward-facing position and a pivotally vertical position. In parallel with the bottom segment position are all sub-segments then in a common, preferably vertical plane.

In another preferred embodiment, the bottom consists of at least two horizontal mutually movable, preferably at least partially cross each other, the ground elements. The floor elements can, for example telescopically interlocking and mutually be displaced.

The invention is further illustrated by the following figures. Show it<dl tsize="16"><dt>Figures 1-6</dt><dd>the schematic sequence of the method in a Sequence of process steps</dd><dt>figure 7</dt><dd>An embodiment of the device according to the invention, wherein the pivotable mold sidewalls is divided into subsegments.</dd><dt>figure 8</dt><dd>a plan view of the device of Figure 7</dd><dt>Figures 9 to 11</dt><dd>the schematic sequence of the method in a Sequence of process steps, in which an apparatus with mutually movable floor elements is used.</dd></dl>

In Figures 1 to 6 is the flowchart of the inventive method by filling the mold box presented to the removal of the foam block.

Figure 1 shows an inventive device 1 for the production of foam blocks in Flake composite comprising a trolley 2 on which a molding box 3 is arranged. Of the Molding box 3 itself comprises a bottom 4, are fixed to the pivotal axes 5a and 5b, by means of which the mold side walls 6a and 6b from the vertical position to an outwardly facing Position can be pivoted. In Figure 1 of the mold box is shown in the state in which the mold side walls 6a and 6b are pivoted into the outwardly facing position.

The blended with the binder foam flakes 8 to a transport device 7, which is disposed above the flask 3, fed into the molding box 3 until the desired Degree of filling is reached.

Figure 2 shows a top view of the flask 3 in the state in which the mold side walls 6a and 6b are pivoted to the outward-facing position. Prior to the start of filling the base 4 is not covered with foam flakes.

Figure 3 shows the molding box 3 after filling with the plastic foam flocks. Due to the Net weight of the foam flakes, the density of the plastic foam flocks in the bed 9 with increasing distance off the ground. 4 This is shown in Figure 3 by a decreasing upwards Density of hatching depicted.

Figure 4 shows the molding box 3 after the mold side walls 6a and 6b in the vertical position have been pivoted back, so that a height over the constant cross section of the mold box results. The pivoting movement of the mold side walls 6a, 6b is through the two Arrows symbolizing. By the pivoting of the mold side walls 6a, 6b to the vertical position the foam particles in the bed 9 are compressed, the foam flocks to are more compressed the greater their distance from the ground. 4

Figure 5 shows the molding box 3 after the plunger 10 into the molding box 3 in the vertical direction was driven into it and the bed to the desired block height or the desired has compacted density to obtain a foam block.

After the mold residence time of the finished foam block 11 is removed from the mold by the plunger 10 and the mold side walls 6a, 6b to be peeled off as far upwardly that the foam block 11 freely rests on the ground 4, and can be removed. This condition is shown in Figure 6 shown. Alternatively, after the punch has been withdrawn upwards for example, but also the shape of the side walls are folded outwards.

Figure 7 shows a particular embodiment of the device according to the invention containing 21 a trolley 22, on which a mold box 23 is disposed. contains the form box itself a bottom 24, are fixed to the pivotal axes 25a and 25b. Both in Figure 7 shown, opposite form side walls 30a, 30b are each respectively in a lower Sub-segment 26a, 26b and an upper portion segment 27a, 27b divided.

The two lower sub-segments 26a, 26b stand on the horizontal pivot axes 25a, 25b and are releasably connected with them by holding devices. The upper edges of the lower Subsegments 26a, 26b are connected to the lower edges of the upper sub-segments 27a, 27b on horizontal Pivot axes 28a, 28b in the form of a joint.

In the illustration in Figure 7, both the lower portion segments 26a, 26b and the upper Subsegments 27a, 27b pivoted to the outward-facing position. Here are the top Subsegments 27a, 27b tilted to a greater angle than the lower portion segments 26a, 26b, for example, a determined in preliminary uneven compaction during subsequent compensate pressing. As indicated by the arrows, the subsegments 26a, 26b, 27a, 27b after the filling of the molding box 23 with the foam flocks again in the vertical Position (indicated by the dotted lines) are swung back.

Figure 8 shows a plan view of the mold box 23 shown in Figure 7 comprising the soil 24, the hinged side walls form with the lower part of segments 26a, 26b and the top Subsegments 27a, 27b and the two fixed form sidewalls 29th

In Figure 9, a preferred embodiment of the inventive device 41 is shown. It contains a trolley 42, on which a molding box is arranged 43rd The flask 43 includes a bottom 44, the telescoping of a central, partially hollow base plate 45 and two displaced, in the middle bottom plate 45 partially retractable floor elements 46a and 46b consists. At the outward-pointing ends of the retractable floor elements 46a and 46b each horizontal pivot axes 47a, 47b are fixed, by means of which the shape of side walls 48a, 48b pivoted from the vertical position to the outward-facing position can be. The flask is further provided with a vertically movable mold cover 49 equipped, in which the punch 50 is integrated to the pressing of the foam flakes.

In the state shown in Figure 9, the two retractable floor members 46a and 46b been driven from the central bottom plate 45 to the outside and the form of side walls 48a and 48b has been pivoted into the outwardly facing angle. The mold box 43 is then ready for filling with the foam flocks provided with binders. After the filling the mold cover 49 is then lowered and placed on the molding box 43rd

After filling the mold box 43 with the foam flakes and placing the mold lid 49 are - as shown in Figure 10 - the form side walls 48a and 48b back into the vertical position pivoted back and the two retractable base elements 46a and 46b (Not seen in Figure 10) into driven back to the center floor panel 45 so that a over the filling total scaled and over the height of the flask 43 constant cross section of the molding box results. The mold box 43 is then ready for the compression the foam flakes.

The pressing is carried out by lowering the punch 50 until the desired height of the foam block or the desired density is reached. The foam particles are between the central base plate 45 and the punch 50, the located in the vertical position form sidewalls 48a, 48b and the two fixed side walls 51 trapped. Before the Unmolding must remain so long in the mold box 43 the foam block until a firm bond has set between the foam flakes and binder.