EP0167953B1 - Method and apparatus for producing plywood cores - Google Patents

Abstract

1. Method of producing plywood cores, in which strips of wood (10) are supplied with glue and joined together to form a carpet of strips and are connected to one another in a heated pressure and glueing zone (4), characterized by the following features : a) a group of strips (10) which run parallel and are laterally spaced are delivered simultaneously ; b) the glue is supplied in the gap formed by the lateral spacing of adjacent strips ; c) the group of simultaneously delivered strips is attached jointly to the carpet of strips which is already present.

Description

The invention relates to a method (corresponding to the preamble of claim 1) and a device (corresponding to the preamble of claim 2) for the production of middle layers.

The middle layer is the wood layer of blockboard between the barrier veneers. The middle layer usually consists of individual strips, preferably connected by glue. It ensures the flat shape of the finished blockboard.

Middle layers are usually produced in middle layer gluing machines. The strips are placed individually on a front table and shot into the machine at high speed by a chain belt. At the same time, a thin glue thread is applied to the strips. The machine joins the individual strips prepared in this way close together. The fully formed area of the strip of carpet then enters a heated pressure and glue zone.

A method of the type required in the preamble of claim 1 and a device according to the preamble of claim 2 is described, for example, in Lüger “Lexikon der Technik” 1968, Volume 9, Deutsche Verlagsanstalt Stuttgart, pages 77, 78.

The main disadvantage of the known method lies in the power limitation. An increase in performance can only be achieved by increasing the speed at which the individual strips are shot into the gluing machine. As the speed increases, however, the kinetic energy of the bars increases, which must be destroyed when the bars impact a stop. The high kinetic energy entails the risk of damage to the strips and the resulting malfunctions. Another disadvantage of the known method is that generally only one operator can work on the machine, sorting and presenting the individual strips to be shot. For this reason, there are strict limits to an increase in performance.

A method is also known (US-A 2572772) in which a group of plywood strips lying directly next to one another are passed between two glue rollers and are thereby provided with glue on their exposed outer sides. This strip group is then attached to an outside of a stack of strips, from the top of which the strips are removed in layers and fed to a press. The handling of this process is cumbersome overall and does not allow high production speeds.

The invention is based on the object of further developing a method of the type required in the preamble of claim 1 and a device according to the preamble of claim 2 such that a substantial increase in performance is achieved - while maintaining a reliable, trouble-free operating sequence.

This object is achieved according to the invention with respect to the method by the characterizing features of claim 1 and with respect to the device by the characterizing features of claim 2.

By simultaneously feeding a group of strips at the same time according to the invention, there is a significant increase in performance without the need for critical insertion speeds. The simultaneous feeding of a group of parallel strips also makes it possible to employ a number of operators for sorting and preparing the strips and thereby also creating the conditions for a considerable increase in performance on the feed side.

However, the prerequisite for the solution according to the invention is that the group of the strips supplied simultaneously and in parallel is supplied with glue in a faultless and uniform manner. For this purpose, the strips fed in parallel are held at a lateral distance, the glue being added in the space formed by the lateral spacing of adjacent strips.

In the gluing machine, the group of strips fed in at the same time is then added to the existing carpet of carpets, while eliminating the gaps between these strips.

Appropriate embodiments of the invention are the subject of the dependent claims and are explained in connection with the description of an exemplary embodiment illustrated in the drawing.

• Fig. 1 und 1 b eine (auf zwei Zeichnungsblätter verteilte) Aufsicht auf eine erfindungsgemässe Vorrichtung,
• Fig.2 einen Schnitt längs der Linie 11-11 der Fig. la,
• Fig. eine Aufsicht (in vergrössertem Massstab) auf das Detail 111,
• Fig. 4 einen Schnitt längs der Linie IV-IV der Fig. 1 b,
• Fig. eine Seitenansicht (in vergrössertem Massstab) in Richtung des Pfeiles V der Fig. 1 b,
• Fig. einen Schnitt längs der Linie VI-VI der Fig. 5,
• Fig. 7 eine Aufsicht (in vergrössertem Massstab) auf das Detail VII der Fig. 1 b,
• Fig. 8 eine Seitenansicht in Richtung des Pfeiles VIII der Fig. 7,
• Fig. 9 eine Stirnansicht in Richtung des Pfeiles IX der Fig. 7,
• Fig. 10 einen Schnitt (längs der Linie X-X der Fig. 7) durch das Düsensystem,
• Fig. 11 einen Schnitt längs der Linie XI-XI der Fig. 1 b,
• Fig. 12 eine Aufsicht (in vergrössertem Massstab) auf das Detail XII der Fig. 1 b.

Show in the drawing

• 1 and 1 b a (distributed over two drawing sheets) top view of a device according to the invention,
• 2 shows a section along the line 11-11 of FIG.
• FIG. 1 shows a top view (on an enlarged scale) of detail 111,
• 4 shows a section along the line IV-IV of FIG. 1b,
• 1 is a side view (on an enlarged scale) in the direction of arrow V in FIG. 1b,
• 5 shows a section along the line VI-VI of FIG. 5,
• 7 is a plan view (on an enlarged scale) of detail VII of FIG. 1b,
• 8 is a side view in the direction of arrow VIII of FIG. 7,
• 9 is an end view in the direction of arrow IX of FIG. 7,
• 10 shows a section (along line XX of FIG. 7) through the nozzle system,
• 11 shows a section along the line XI-XI of FIG. 1b,
• Fig. 12 is a plan (on an enlarged scale) on the detail XII of Fig. 1 b.

The device according to the invention for the production of middle layers, shown schematically in top view in FIGS. 1 and 1, essentially contains a conveyor device 1 for feeding in each case a group of strips in a parallel position with a lateral spacing, a device 2 for adding glue into the space between adjacent strips, a device 3 for attaching a group of parallel strips to the existing strip of carpet as well as a heated pressure and gluing zone 4.

• - ein Zubringerband 5, das aus einer Vielblattsäge 6 kommende Leisten zu Sortierstationen 7 führt, von denen in Fig. 1a lediglich eine Sortierstation 7 dargestellt ist,
• - ein von den Sortierstationen 7 beschicktes Stegband 8, das mit parallel und mit seitlichem Abstand angeordneten Stegen 8a versehen ist, die zur Ausrichtung und Distanzierung der Leisten dienen,
• - ein sich an das Stegband 8 anschliessendes und bis zur Leimzugabeeinrichtung 2 erstreckendes ortsfestes Führungssystem 9, das die Leisten 10 in paralleler Lage und mit seitlichem Abstand hält,
• - ein sich an das Stegband 8 anschliessendes, die Leisten 10 durch eine Pufferzone 11 transportierendes Förderband 12,
• - eine sich an das Förderband 12 anschliessende Synchronvorschubeinrichtung 13 zur synchronen Einführung jeweils einer Gruppe von Leisten in den Einführraum 14 der Druck- und Verleimzone 4.

The conveyor device 1 for feeding a group of strips in each case essentially contains the following elements:

• a feeder belt 5, which leads strips coming from a multi-blade saw 6 to sorting stations 7, of which only one sorting station 7 is shown in FIG. 1a,
• a web belt 8 which is fed by the sorting stations 7 and which is provided with webs 8a which are arranged in parallel and at a lateral spacing and are used for aligning and spacing the strips,
• a stationary guide system 9 which adjoins the web strip 8 and extends to the glue addition device 2 and which keeps the strips 10 in a parallel position and at a lateral distance,
• a conveyor belt 12 adjoining the web belt 8 and transporting the strips 10 through a buffer zone 11,
• a synchronous feed device 13 adjoining the conveyor belt 12 for the synchronous introduction of a group of strips into the insertion space 14 of the printing and gluing zone 4.

The sorting stations 7 are equipped on both sides of an operator 15 with a saw 16, 17 each. As can be seen in FIG. 2, the web belt 8 lies somewhat lower than the feed belt 5. Above the web belt 8 there is a buffer belt 18 which is guided into the buffer zone 11, which in FIG. 1 b is only schematic with a single operator 19 is shown. In the area of the sorting stations 7 there is also a magazine 20 for unsorted goods, as well as a conveyor belt 21 for the removal of the waste.

The webs 8a of the web belt 8 run parallel to the conveying direction. Their mutual distance is somewhat larger than the width of the strips 10 (if these are placed on the web strip 8 in the position provided for the gluing, rotated by 90 ° relative to the cut in the multi-blade saw 6).

The stationary guide system 9 extends from the discharge-side end of the web belt 8 through the synchronous feed device 13 to the glue addition device 2. It contains a number of guide belts 22 (see FIG. 4) arranged in parallel and at a lateral spacing, which are arranged at certain intervals via holding belts 23 are suspended on fixed brackets 24 in such a way that they can be moved to a limited extent transversely to the conveying direction (double arrow 25, FIG. 4). The strips 10 run between the guide belts 22 and are transported by the conveyor belt 12 running closely below the guide system 9.

The transition of the strips 10 from the discharge-side end of the web belt 8 (deflection axis 26) to the adjoining conveyor belt 12 (inlet-side deflection axis 27) is shown in FIG. The guide bands 22 are provided with a rounded widening 22a at their inlet end. This prevents strips from blocking when they hit guide belts 22.

The synchronous feed device 13 (see FIGS. 6 and 6) contains a number of paired upper and lower rollers 28, 29, between which the strips 10 pass. The upper rollers 28 are subdivided according to the strip width (cf. FIG. 6) and contain a knurled outer steel ring 28a which is arranged on a rubber ring 28b. The lower rollers 29 are formed continuously, provided with grooves and appropriately knurled on the circumference. The guide bands 22 are provided in the spaces thus formed. The upper rollers 28 can be pressed in the direction of the lower rollers 29 by a hydraulic or pneumatic actuation device (not shown), so that the strips 10 are transported synchronously when the lower and / or upper rollers are driven.

A monitoring device 30, which is only indicated schematically, is arranged in front of the synchronous feed device 13. It determines whether there is a ledge 10 in each ledge channel (between adjacent guide bands 22) and whether no ledge channel is occupied twice by ledges.

The device for adding glue in the space between adjacent strips is shown in detail in FIGS. 7 to 10. The device 2 contains a nozzle system 31 (FIG. 10) for each ledge channel, the nozzle systems 31 assigned to the adjacent ledge channels being offset relative to one another in the conveying direction (cf. FIG. 1b).

The nozzle system 31 is detachably connected to the end of the associated guide band 22 via a web part 32. For this purpose, in the exemplary embodiment shown, a bushing 34 is fastened to the guide band 22 via a holder 33, through which a bolt 35 connected to the web part 32 engages. The connection is made via a nut 36. The detachable connection between the nozzle system 31 and the associated guide band 22 permits simple replacement of the nozzle system 31, in particular for cleaning and maintenance purposes.

The nozzle system 31 (see FIG. 10) contains a hydraulic or pneumatic actuating cylinder 37, the piston rod 38 of which is connected to a nozzle needle 39, which is abge in its lowered position interrupts the connection between a glue supply opening 40 and a nozzle channel 41. The nozzle channel 41 opens out on a side wall of the web part 32 (cf. FIG. 9) and feeds glue (in the direction of the arrow 42) to the adjacent one side surface 10a of the strip 10. In this way, the strips running past the nozzle systems 31 receive a glue thread 43 schematically indicated in FIG.

The insertion space 14 of the heated pressure and gluing zone 4 is intended for receiving a group of strips 10 fed in parallel and simultaneously. This insertion space 14 is delimited at the end by an adjustable end stop 44. An I <app saw 45 is arranged in the area of the entry side. Furthermore, a slide ./1,3 is provided which is adjustable in the direction of arrow 48 by a number of only schematically indicated hydraulic or pneumatic actuating cylinders 47 and thus pushes the strips introduced into the insertion space 14 transversely to their feed direction onto the existing carpet of strips .

On the side facing away from the slide 46, the insertion space 14 is delimited by a stop bar 49 which can be raised and lowered.

The heated printing and gluing zone 4 contains bar-shaped heating registers 54, 55 on the upper and lower sides, of which the upper heating registers 54 can be adjusted in height to the respective strip thickness. By means of springs (not shown), a uniform, adjustable pressure is exerted on the middle layer 52 of the blockboard 52 which arises in the pressure and gluing zone 4 and which moves further in the direction of the arrow 53 when a further strip group is inserted. The antechamber 14 of the printing and gluing zone 4 is delimited on the upper side by a profile 50 and on the underside by a table 51. The middle layer is thus produced using the method according to the invention as follows:

The dried board goods are cut into strips in the multi-blade saw 6, which then run on the feeder belt 5 to the sorting stations 7. At the sorting stations 7, the operators 15 remove the strips from the feeder belt 5, examine them and, if necessary, cut out errors from the strips. In order to avoid turning the strips during this cutting, there are 7 saws 16 and 17 in each sorting station on both sides of the operator 15.

The good strips are then placed on the web strip 8, in such a way (generally flat) that the cut surfaces are above or below. The operator can place excess sorted bars on the buffer belt 18. On the other hand, if there is too much unsorted goods, this is first stored in the magazine 20.

At the end of the sorting line consisting of several sorting stations 7, the strips 10 pass from the web belt 8 to the smooth conveyor belt 12, which runs under the stationary guide system 9. The conveyor belt 12 transports the strips through the buffer zone 11, at the end of which at least one operator 19 is arranged. It ensures that all strip channels (between the parallel guide bands 12) are filled with strips. If necessary, it takes sorted strips from the buffer belt 18 and thereby fills an empty strip channel. In addition, the monitoring device 30 monitors the correct filling of all groin channels. If the monitoring device responds when an irregularity is detected, the synchronous feed device 13 is stopped immediately and the glue addition is interrupted.

As can already be seen in the drawings, both the spacing of the webs 8a of the web band 8 and the spacing of the guide bands 22 are selected to be somewhat larger than the width of the strips 10 in order to take account of deviations of the strips from the straight position (ie warpage of the strips) .

The strips 10 then run through the synchronous feed device 13. The elastic design of the upper rollers 28 compensates for any differences in thickness of the strips.

After passing through the synchronous feed device 13, the strips pass through the device 2 for adding glue, and are kept in a parallel position and at a lateral distance up to this device 2 by the guide belts 22 of the stationary guide system 9.

Then the strips provided with glue reach the insertion space 14 of the pressure and gluing zone 4. The length of the inlet is determined by the adjustable end stop 44. Shortly before the desired length is reached, when the end stop 44 is touched for the first time, the feed (by the synchronous feed device 13) is reduced to the creeper gear. When the exact end position is reached, the feed is switched off.

The upper profile 50 of the insertion space 14 can be raised and lowered. When the strips 10 run into the insertion space 14, the upper profile 50 is in the raised position. After switching off the bar feed, the upper profile 50 is lowered and now presses the bars 10 to the same height. Then the bar band is cut to the desired length by the chop saw 45.

Subsequently, the strip of strips is pushed into the printing and gluing zone 4 by the slide 46, the strip of strips being pressed onto the strip of carpet already located in this printing and gluing zone 4 and glued to it. When each further strip of strips is pushed in, the middle layer 52 located in the printing and gluing zone 4 is pushed further by the strip width of the strip. At the end of the (not fully shown) printing and gluing zone, the endless middle layer is cut into individual plates.

Fig. 12 illustrates one of the inventions Possibility given to the method according to the invention to also utilize strips 56 with defects on one side (for example with a tree edge). These strips 56 are inserted into one of the two outer strip channels. In the area of the feed synchronizing station, a re-milling device 57 is arranged adjacent to one or both outer ledge channels, which mills off the defective edge of the ledge 56 during the feed movement. In contrast to the known method, in which only one strip is enclosed in the antechamber of the printing and gluing zone (and for which reason a constant strip width is required), faulty strips can also be used to a certain extent in the method according to the invention by cutting these strips in the outer strip channels to a reduced width compared to the strips in the other strip channels. The wood utilization is significantly improved in this way.

Claims (9)

1. Method of producing plywood cores, in which strips of wood (10) are supplied with glue and joined together to form a carpet of strips and are connected to one another in a heated pressure and glueing zone (4), characterised by the following features:

a) a group of strips (10) which run parallel and are laterally spaced are delivered simultaneously;

b) the glue is supplied in the gap formed by the lateral spacing of adjacent strips;

c) the group of simultaneously delivered strips is attached jointly to the carpet of strips which is already present.

2. Apparatus for producing plywood cores, containing

a) a conveyor arrangement (1) for the delivery of strips (10),

b) an arrangement (2) for supplying glue,

c) an arrangement (3) for attaching strips (10) to the existing carpet of strips,

d) a heated pressure and glueing zone (4), characterised by the following features:

e) the conveyor arrangement (1) which serves for the delivery of each group of strips (10) in a parallel position with lateral spacing contains:

e₁) a delivery belt 5 which leads to the sorting station,

e₂) a barred belt (8) which is supplied from the sorting stations (7) and is provided with laterally spaced bars (8a) which are arranged parallel and with lateral spacing and serve to align and distance the strips (10),

e₃) a stationary guide system (9) which adjoins the barred belt (8) and extends as far as the glue supply arrangement (2) and holds the strips (10) in a parallel position and laterally spaced,

e₄) a conveyor belt (12) which adjoins the barred belt (8) and transports the strips (10) through a buffer zone (11),

e₅) a synchronised feeding device (13) adjoining the conveyor belt (12) for the synchronised introduction of each group of strips (10) into the inlet chamber (14) of the pressure and glueing zone (4), guide system (9) extending through the synchronised feeding device (13);

f) the arrangement (2) for supplying glue contains for each strip channel a nozzle system (31) which is controllable by means of a nozzle needle (39), the nozzle systems (31) associated with adjacent strip channels being offset with respect to one another in the transport direction;

g) an inlet chamber (14) of the pressure and glueing zone (4) intended to receive each group of strips (10) is defined in the direction of delivery of the strips by an adjustable end stop (44);

h) the arrangement (3) for attaching each group of parallel strips (10) to the carpet of strips which is already present contains a slide (46) which is movable at right angles to the direction of delivery of the strips.

3. Apparatus as claimed in claim 2, characterised in that the stationary guide system (9) contains a plurality of guide bands (22) which serve for alignment and distancing of the strips (10), are arranged parallel and laterally spaced and are suspended on stationary mountings (24) so as to be capable of limited movement at right angles to the transport direction.

4. Apparatus as claimed in claim 3, characterised in that the guide bands (22) are each provided with a preferably rounded wider part (22a) at their intake ends.

5. Apparatus as claimed in claim 3, characterised in that the synchronised feeding device (13) contains a plurality of rollers (28, 29) which work together in pairs and of which the upper rollers (28) which are preferably sprung are divided corresponding to the width of the strips and engage in the gap between adjacent guide bands (22).

6. Apparatus as claimed in claim 3, characterised in that the nozzle systems (31) are arranged at the ends of the guide bands (22) and are preferably releasably connected to the latter.

7. Apparatus as claimed in claim 2, characterised in that a buffer belt (18) is provided parallel to the barred belt (8) and to the adjoining conveyor belt (12).

8. Apparatus as claimed in claim 2, characterised in that a cutting arrangement (57) is provided preferably in the region of the synchronised feeding device (13) adjoining at least one of the two strip channels and by means of this cutting arrangement strips (56) which are flawed on the outside and are located in the outer strip channel are cut to a width which is reduced by contrast with the strips (10) in the other strip channels.

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