DE3222122C2 - Method and device for compression molding a molding to form a one-part or multi-part pallet - Google Patents

Abstract

The invention is concerned with the compression molding of one-piece pallets or of pallet base bodies, the protruding base parts of which are connected to one another by beams, from small vegetable parts mixed with binding agents. To increase the strength of these moldings and to avoid breakage during pressing and later handling, the foreign body is gradually compressed with compression molds (10, 13, 15) which can be moved relative to one another. First, the top and bottom (13, 10) are pre-compressed between initially stationary, lateral molds (15). The side surfaces (18) of the molding are then embossed, while the pressure acting on the top and bottom (13, 10) is canceled. In the last working stage, the top and bottom (13, 10) of the molding are compressed to the desired size, but the pressure of the side molds (15) is maintained.

Description

The invention relates to a method for compression molding a shaped body to form a one or multi-part pallet according to the preamble of the main claim, to a device for performing this method, and to a special design of the pallet bars.

From DE-OS 25 08 493 it is known to use entire pallets with feet arranged in one piece thereon Binder to extrude mixed small plant parts, whereby the feet in particular should be compacted in the bridge. Such a theoretical and in the Doctrine that cannot be used in practice does not lead to sufficient strength because the small parts are normally oriented transversely to the direction of extrusion and thus bring about a very low flexural strength.

It is also known from US Pat. No. 4,248,163 to press a one-piece pallet made of glued wood chips in a die that has a stationary lower mold and has a movable upper mold. The pallet feet are hollow. This palette shows often weak points and breaks on the walls of the pallet feet.

In order to eliminate the weak points, the wall is stepped in accordance with the teaching of DE-AS 11 65 250 formed, for what purpose several, nested ram simultaneously or successively be driven up to the limit that gives the shape.

Nevertheless, in practice, weaknesses in the wall or even wall breakthroughs can often be observed are probably due to the fact that the small pieces of wood mixed with binding agent come together during pressing behave differently than a homogeneous plastic mass.

DE-OS 30 35 701 teaches several pallet feet with them connecting beams in a form to press massive pallet bars and these pallet bars to be trained so that they can withstand high bending loads. One strives for the between The recessed beams located on the pallet feet are stronger than the remaining areas of the pallet feet to condense, which actually creates a larger one Strength and rigidity against bending stress is achieved. In addition, these are pallet bars provided with lateral embossing to increase strength.

The invention is based on the object of a one-piece pallet or, in the case of multi-piece pallets, their bolt Vegetable and small parts mixed with binding agents to be pressed into molds in such a way that compared to the known Measures significantly increased strength and lower sensitivity in handling achieved without having to increase their weight.

This object is achieved according to the invention with the characterizing features of the main claim

The invention is based on the known knowledge that the chips are in a compression molded plate preferred paraüc! to their. Orient the surface. Ever But the thicker such a plate is, the more randomly the chips lie in the middle plate area. Above all this phenomenon is to be assumed if the pressed body deviates considerably from the rat shape.

Therefore, the invention strives with its characteristic means, a certain chip orientation at all To force places that are subjected to high loads or to increase strength are relevant. With the gradual compression of the mixture by staggered and intersecting Compression molds that can be moved against each other in planes cause targeted movements in the chip structure, whereby the chips are oriented parallel to this on practically all surfaces. Goes inside this orientation is transformed into a convex or concave curvature in relation to the direction of loading, which allows the molded parts are thinner-walled and therefore easier to carry out without sacrificing strength to have to.

It has been shown that with the method according to the invention, both one-piece pallets (display pallets) as well as pallet bars for the formation of multi-part and particularly stable pallets can be produced.

The measures according to claims 2 and 3 lead above all to the massive pallet bars to make it particularly stable and to create the vault structure with high-strength, compacted outer layers. On the other hand, this vault structure is apparently the reason why ss with the features of the claims 4 to 6 succeed in compressing the side surfaces, which are susceptible to known pressed pallets, in such a way that also there a very substantial increase in strength and a desired chip orientation in parallel Surprisingly, however, the corner areas of the pallet bars or pallets also enter the side surface a substantial compression and idiosyncratic chip orientation with corresponding impact insensitivity, although weakening would most likely have been expected there.

The application of the teaching according to the invention to the aforementioned manufacturing technique for one-piece Pallets of known type mean that when increasing the strength and reduction in weight completely eliminates the damage to the walls of the pallet feet be avoided.

In the apparatus claims 7 to 12 are expedient \ s' practical embodiments of the apparatus disclosed for performing the method according to the invention, wherein the claim 7 extending from the initially mentioned DE-AS 11 65 Z50

The formation of the pallet feet according to claims 13 to 15 leads to greater rigidity of the Paiette and better connection of the pope feet or Pallet bar with the pallet boards, which counteracts the risk of tipping through mutual eccentric support The invention is shown schematically in several examples in the drawing. It shows

F i g. 1 is a perspective view of a latch bolt,

F i g. FIG. 2 shows a cross section through a compression molding press for the production of the pallet bar according to FIG. 1,

F i g. 3 to 5 cross-sections through the compression molding press according to FIG. 2 in different pressing phases,

F i g. 6 is a cross-section through a compression molding press for the production of one-piece pallets, shown a pre-pressing process,

F i g. 7 one. Cross section according to FIG. 4 with illustration a lateral pressing process,

8 shows a cross section according to FIGS. * And 5 with Representation of a re-pressing process, FIG. 9 shows a partial cross section corresponding to FIG. 6 in vei enlarged representation,

F i g. Fig. 10 is a cross-section through a portion of a pressed pallet as viewed from FIG. Lines xx of FIG. 9,

F i g. 11 a cross section through the pallet base of a Pallet bar and

F i g. 12 a top view of the pallet bar according to FIG. 11.

The pallet bar 1 according to FIG. 1 basically has an elongated cuboid shape, the upper side (roof surface 16) of which is flat and the lower side of which is formed by pallet feet 2 and indentations between them, the transition of which should have a strong curvature 6. The lower surfaces of the pallet feet 2 are parallel to the roof surface Ü6. The beam 3 remaining in the area of the devices 5 must be of such strength that the pallet bar 1 withstands considerable loads, in particular bending loads. In order to increase the strength, 1 embossments 4 are pressed into the side walls of the pallet bar, which are shown in FIG. 1 are indicated by dash-dotted lines.

It is possible to use the one shown in FIG. 1 illustrated pallet bars with different collections of finer and to manufacture coarse small parts.

With Fig. 2 a cross section of a compression molding press is shown, as it corresponds for example to the section H-II in Fig. 1 through the pallet bar 1, if you look

5 6

for this purpose, a pressing area of the pallet bar 1 encompassing the pallet bar 1 is brought about,

of course, the edges of the compression molding

Then the in F i g. 2 illustrated molding press pelteiles 15 rounded This has in the basic position

initially formed by guides 7 of a stationary type, with the result that open flutes 20 (cf.F i g. 3) are formed

between which compression dies 10, 11, 12, 13 are movable 5 det, which are filled by the pre-pressed material

are led. The compression molding die 13 (see FIG. 3) is the and therefore form protruding burrs. These ridges

in the illustration in FIG. 2 in a not shown, but are removed when the inner compression molding

raised position moved back in order to free space to master stamp parts 15 in the position according to FIG. 4 in advance

Chen for a feed chute 8 through which the binders can be moved.

Medium-mixed chip mixture in the press chamber 9 if it was previously said that everyone can mold lengths. All of the compression dies 10 shown, the die part is assigned its own lifting drive, 11, 12 are in a set back position then this does not exclude that moving in the same direction, gear position. It is assumed that in the but separate molding die parts Pressing chamber 9 a metered amount of the mixture is connected to the volume of the bridge-like structure to be produced, each with a press cylinder pallet bar 1, or the like lifting element, shes is filled. In Fig. 5 it is now shown that while maintaining the

After completion of the filling process, which in QbIi position of the compression die parts 15 a kind of compression

is carried out in a rather manner, is carried out at a first exit by the compression die 10,13,

exemplary embodiment of the invention of the compression molding die The movement of this compression molding die 10, 13 leads

13 moved into the position shown in Figure 3. At the same time 20 then for the final shaping of the pallet bar

can the opposite compression die 10 in 1. It can be imagined that this upsetting

the in F i g. 3 position shown can be moved. The process according to FIG. 5 which near the rounded

Lateral compression die 11,12, however, remain gene 23 of the compression die parts 15 located chips

In this exemplary embodiment, the in or small parts initially experience a kind of shifting process.

F i g. 2 position shown. The consequence of this first advance was the movement of the compression molding

The first pressing process is that a part of the small part? 15 according to FIG. 4 already in one of the press surfaces

parts parallel to the compression molds 10, 13 have been brought into an approximately parallel position. That

represents As the F i g. 3 shows, is by the compression molding according to F i g. 5 now requires an enveloping one

stamp 10,13 the bottom surface 17 or the roof surface compaction of the material in the area of the curved

16 of the pallet bar 1 is formed in this moving 30 upper passages. The redensification according to FIG. 5

Gen the compression die 10.13 pre-compressed material also leads to a considerable stiffening of the

al can be something in the direction of the FIG. 2 back - entire pallet bar 1.

offset lateral compression molds 11,12 auswei- You can now what in the drawing with respect to chen and there still an indeterminate positional orientation of the side compression molds 11, 12 disclosed whateinhaben. 35 den is also on the lower compression die 10

After this first pressing process has been completed, it will turn. In the example of FIG. 2 to 5 was left open-

the pressure of the FormpreSstempei i0.13 lifted. whether this ForrnpreSsieiTJpc! «0 of ours

If now in the course of a second section of the contour of the pallet bar 1 follows you can pre-press the lateral compression die 11, this compression die 10 also along the pallet belt 12 in the form shown in FIG. 3 are moved forward, ao gels 1 divided by one parts of the pallet while the compression die 10, 13 in their Vorpreß- tenfüßei. 7 and the other parts of the indentations 5 remain in position, a layer-by-layer position orientation of the pallet bar 1 is assigned. When pre-pressing the small parts parallel to the pressing surfaces according to FIG. 2 and 3, the compression ram 11, IZ on the side of the compression chamber 9 can still lie in one plane. In a

It has been shown that the Lageorientiemng the 45 intermediate phase, not shown in the drawing, the Small parts in this described according to the invention are expediently between those of FIGS. 3 and 4 After-and-after pre-pressing is much cheaper than with Hegt, the indentations 5 can then be formed

the closer measure is in the case of all the compression die parts for themselves against the stationary

Compression ram are simultaneously moved into the final upper compression mold 13 remaining to be pressed

position is moved forward a 50 Profiling of the pallet feet 2 opposite the Rinbuch

The in F i g. 3 pre-pressed pallet latches shown 19 lines 5 to form. But it is also conceivable with one

has opposite the final shape of the Palettenrie- uniform lower compression molding die 10, which the

gels 1 is still excessive. It is now shown that the minimum contour of the pallet bar 1 is adapted accordingly

at least the side compression dies Ii, 12 in several parts of the F i g. 3 to work.

are trained. Between two outer compression molding 55 In the F i g. 6 to 8 is a variant of the

stamp parts 14 is an inner compression molding stamp part 15 of the method according to the invention is shown schematically

arranged to be movable relative to each other.

preßstempeheil 14,15 is its own lifting drive (but does not pull on the production of pallet bars

shown) assigned On the way from the position according to Fig. 1 can be applied,

development according to FIG. 2 to that according to FIG. 3 are all 60. The pallet 24 should be several, spaced apart

Compression die parts 14,15 simultaneously moved forward have PaJettenfüße 2, which are mutually by un-

been. In the further course, however, the interconnections 3 will now be connected. In the example according to

A compression molding die 25 acts over the entire surface of the inner molding die parts 15 from the position

according to fig. 3 m those according to FIG. 4 moved up and down on the shaped mixture

These Fonripreostcfflpeiteile 15 can take the shape of the 03 gc from small vegetable parts, in particular wood shavings

in Fig. 1 have embossing 4 shown. Is essential and binder, and compacts this against the first

so that with this movement of the compression molding die, the lower compression molding die 26, 27 remains stationary.

Ie 15 a strong and final compression of the side, then the lower compression dies 26 are loaded

moves away, while the other lower compression dies 27 are still immobile. Its raw this way The pressed pallet is still too large.

According to FIG. 7, the compression molds 25 to 27 are now slightly lifted. There is no need to go any further to be covered; it is sufficient if only the pressing force is reduced or eliminated. In this solved At the time of the raw pallet 24, the side compression dies 28 are now moving against one another set, which act only on the outer side surfaces of the pallet 24 in the example. It can recommend while holding the lower compression molding die 27 in their original position that this one Have to absorb part of the lateral deformation pressure.

While the lateral compression die 28 in their pressing position while maintaining the pressing pressure remain, according to F i g. 8 the other molding stamps! 25,26 and 27 for the formation of the Palcticn-Sc !! - measured against each other, whereby the pallet 24 is compacted so that it has the required high Maintains load-bearing capacity and flexural rigidity.

It goes without saying that similar to those shown in FIG. 8 side compression die 28 shown on act on the side surfaces of the pallet 24, which are parallel to the plane of the drawing.

If a pallet bar 2 is to be pressed instead of a pallet 24, the side compression dies are not required 28 according to FIG. 7; therefor are the not shown, but mentioned side molding presses from especially of the importance which the imprint 4 according to F i g. 1 generate according to the method described above.

The mentioned venting of the compression mold 25,26,27 In a variant of the invention, it can also be used simultaneously with the pressing of the side compression dies 28 take place.

The compression dies 25 to 28 are (not shown) stepped, corrugated or the like profiled in their pressing surface, depending on the shape the pallet 24 is to receive. In the drawing, for the sake of simplicity, the Thickness of the pallet plate is not shown, which is less than the height of the beams 3, which run around like a frame can. As a result, there is a gradation of the compression molding die 27, unless that for pressing the lower surface of the pallet plate a separate compression molding die or even a stationary die plate is used. The lower compression dies 26 are preferably used exclusively for pressing and recompaction of the pallet feet 2 is used

9 and 10 show a partial section for pressing a pallet foot 2, which sequence the step-wise and time-shifted pressing according to the invention has the upper molding die 25 sets namely during the pressing process according to FIG. 6 a much longer path than the lower compression molding die 26 back, for example in a ratio of 10: 1. At the end this first pressing movement take the compression molds 25, 26 a position according to the dashed lines 29 and 30 a. With the lines 31 and 32, the positions of the compression mold 25,26 at the end of the whole The pressing process refers to the long compression path of the compression die 25 to line 29 the chips of the mixture do not move arbitrarily, but they obviously orientate themselves based on it the various frictional influences. The areas of the mixture that are close to the Fonnwandungen 33 are likely to be subject to greater friction than the more centric areas. Anyway, take in the end of the entire pressing process, the chips have a positional orientation as shown in FIG. 10, after which the pressing surfaces layers 34 adjacent to the compression die are predominantly parallel to these surfaces Have chip orientation, which is known from the surface pressure of chipboard. The middle areas 35, however, have a curved chip orientation, which - in the pressing direction 36 of the compression die 25 seen - runs convex. Such a curved structure contributes considerably to the increase in strength at. It is increased by the fact that the side compression and post-compression take place at different times. Do you want produce a reverse curvature, the pallet must be pressed in a 180 ° turned position.

If hollow pallet feet 2 are to be produced, then the time-shifted, step-by-step method is also recommended Pressing, but understandably

lltt * lll 1114 * 111 Ul »UMIl.lll. ft UIUJU UIVlUI \ .ll ^ I ^ IUILII l \ ailll. L / IL lateral compression according to FIG. 7 can then form ribs, depressions and the like in the walls of the pallet feet, which can also run parallel to the axis of the pallet feet and contribute significantly to the stiffening of the walls.

It goes without saying that the pressed pallets or pallet bars by supplying heat in the pressed State to be hardened in the mold.

Finally, in FIGS. 11 and 12, there is a partial area a pallet bar 1 shown, the pallet foot 2 has a nose-like projection 37, the surface runs flush with that of the pallet bar 1 and which has a downwardly tapered training. on this approach 37 is the associated pallet board 38, which after nailing with the approach 37 as Tilt protection for the pallet bar 37 acts. Such nose-like approaches can also be mere pallet blocks have which can be produced by the method according to the invention, but which are also in the die or even can be manufactured by extrusion.

It has proven to be useful if the nose-like projections 37 at the points of the pallet feet which face the central area of the pallet, which is shown in FIG. 12 by the position of the pallet boards 38 can be seen

For this purpose 3 sheets of drawings

Claims (1)

Patent claims: 1. A method for compression molding a molded body to form a one-piece, molded with Pallet provided with pallet feet or from individual pallet bars made of small vegetable parts mixed with binding agents, the pallet bars projecting pallet feet on their underside and have girders with rounded transitions set back between them, characterized in that the Small parts to form the moldings are gradually compacted by first the upper and Underside to be compressed to the basic shape of the molded body with oversize, then the compression pressure lifted at the top and bottom, then the sides of at least the pallet feet are embossed and finally the top and bottom of the body while maintaining the Pressure on the eyes on the wetness of the Shaped body are compacted. 2. The method according to claim I _1, characterized in that the upper and lower sides of the molded body are compacted offset in time by first compressing the top to form the basic shape of the molded body and then the underside before the side compression takes place 3. The method according to claim 2, characterized in that the shaping compression of the Upper side over a much longer path, for example in the ratio ~ OK: 1, than the compression the bottom is carried out. 4. The method according to claim 1, characterized in that when producing a one-piece pallet, the side impressions are formed only on the outside of the pallet feet and optionally the beams. 5. The method according to claim 1 or 4, characterized in that the side impressions on Pallet feet of one-piece pallets that are also height? can be designed along the load direction be formed progressively. 6. The method according to claim 1, 4 or 5, characterized in that « characterized in that with the embossments ribs or grooves with changing heights and / or Widths are formed. 7. Apparatus for performing the method according to claim 1 or one of the following, consisting of a compression molding press with a plurality of mutually movable guided, a compression chamber enclosing compression molds, which with time offset controlled lifting drives are provided, characterized in that in addition to the formation the top and bottom of the molded body (1, 24) mutually directed compression molds (13, 10 or 25, 26, 27) compression dies (11, 12 or 28) movable transversely thereto for forming the side surfaces of the molded body (1.24) or w> located therein Embossings (4) are provided and that the control of the compression molding die is provided with a circuit which the on the upper and Underside of the molded body cancels the pressure applied when the side compression die (11, 12 or 28) are in the press feed. 8. Apparatus according to claim 7, characterized in that the lateral compression molding die (U, 12) compression die parts (14, 15) with different lengths of stroke. 9. Apparatus according to claim 7, characterized in that the compression rams (26,27) directed against the undersides of the pallet feet (2) and beams (3) are designed divided according to their contour and with strokes of different lengths generating drives are connected. Device according to Claim 9, characterized in that compression dies (26 or 27) moved in the same direction but separated from one another over bridge-like structures are each connected to a Hubeiement. 11. The device according to claim 7, characterized in that the compression die directed against the underside of the one-piece pallet (24) Is formed in one piece 12. Apparatus according to claim 7 or one of the following, characterized in that the hub the Formpreßsiernpei (13,23} forming the top of the molded body is much larger than the stroke the compression die (10, 26, 27) forming the underside, for example in a ratio of 10: 1 is 13. Solid pallet bars produced by the method according to one of claims 1 to 6, consisting of several protruding pallet feet and connecting beams arranged set back, characterized in that the pallet bar (1) at its pallet feet (2) each one transversely to the longitudinal direction of the pallet bar (1) having extending nose-like projection (37), the surface of which is flush with the surface of the Pallet bar (1) runs. 14. Pallet bar according to claim 13, characterized in that the nasenarti ^ e approach '37 ^ in Direction to the bottom of the pallet feet. (2) is tapered. 15. Pallet bars according to claim 13 or 14, characterized in that the nose-like lugs (37) extend in the direction of the adjacent pallet bar (1).