EP0457720B1 - Feeding device for a machine for assembling veneer sheets to form a continuous veneer strip - Google Patents

Abstract

The feeding device possesses a belt conveyor having a plurality of conveying belts (15) which are distributed over the width of the feeding device and advance the veneer sheets solely due to the adhesive friction. Furthermore, devices (26) having spacers (27) circulating in orbits are provided, the spacers engaging, along the conveying section next to the conveying belts, between the individual veneer sheets and being carried along by the latter. These devices (26) are arranged underneath the conveying plane. <??>An unrestricted view of the veneer sheets located in the feeding device, perfect processing of thin veneer sheets and a simpler and less expensive design of the feeding device are achieved by these measures. <IMAGE>

Description

The invention relates to a loading device for a machine for assembling veneer strips to form a veneer web by mutually gluing the veneer strips on their longitudinal edges according to the preamble of patent claim 1.

A loading device of this type is known, for example, from German Patent No. 1,628,970. In this loading device, the accumulation conveyor is designed as a roller conveyor, which has in each of the conveyor tracks a series of driven conveyor rollers provided with slip clutches and a series of freely rotatable counter-rollers which are under spring pressure. As a rule, the conveyor rollers are arranged below and the counter rollers above the conveyor level. All of the same-axis conveyor rollers sit together on continuous drive shafts that extend over the entire width of the loading device and are connected at one end to a common drive machine via an engine. The counter rollers are mounted in rows on height-adjustable beams. For predominantly spatial reasons, the devices for guiding the spacers are located above the conveying plane, where they are between the rows of counter-rollers and their holders Find space. Below the conveyor level, there would not be enough space for this due to the continuous drive shafts.

A major disadvantage of the loading device described is the fact that the numerous structures obscure the view of the conveying level or of the veneer strips located in the loading device for the most part. As a result, the operator of the loading device lacks an overview of the orderly sequence of the loading and, in the case of the production of cover veneers, in particular also the view of the surface appearance of the veneer web, which makes it difficult to select suitable veneer strips to form an aesthetically pleasing pattern.

Experience also shows that the roller conveyor provided in the known loading device is suitable for processing thin, e.g. 0.6 mm thick veneer strips are less suitable for the production of cover veneers. In particular, the propulsive force exerted on the veneer strips and conveyed by the slip clutches cannot be metered finely enough, so that under certain circumstances excessive forces occur on the pent-up veneer strips, which can damage the veneer strips.

Otherwise, the means for building this accumulation conveyor and for operating it are rather complicated and expensive. In front The large amount of material and the cost of producing a large number of bearing and gear parts are relatively high in this type of accumulator conveyor.

Another solution is the loading device according to DE-PS 28.28.901. It describes a machine for assembling and gluing veneer strips, in which in each case a plurality of veneer strips, previously fixed in their mutual position, are glued together to form plates between two printing plates . A feed table that can be moved back and forth serves as the loading device, on which the veneer strips are laid out in the desired arrangement. There are no grants. On the other hand, spacers are provided which can be moved manually in several grooves of the delivery table or which are pushed towards the previously placed veneer strips with the manually supplied veneer strips. The delivery table is then pushed between the printing plates with the veneer strips provided. In this position, the veneer strips are fixed to the upper pressure plate, whereupon the delivery table can be brought back again. The veneer strips are then joined and glued in the machine.

However, this machine is not suitable for automatically feeding the veneer strips to a gluing machine for the continuous production of veneer sheets.

It is the object of the invention to improve a loading device of the type mentioned at the outset in such a way that it keeps a clear view of the veneer strips located in the same, that it enables the perfect processing of thin veneer strips, and automatically feeds the veneer strips to a gluing machine for the continuous production of veneer sheets and that it has a simpler and less complex design.

This object is achieved according to the invention by the features specified in the characterizing part of patent claim 1.

By using a belt conveyor of the type mentioned, the view of practically the entire conveyor level can be kept free by the drive and guide means of the conveyor belts being located below the conveyor level. In addition, the space required for these drive and guide means is limited to the edge parts of the conveying plane, so that there is sufficient space for the devices for guiding the spacers below the conveying plane.

Experiments have also surprisingly shown that such a belt conveyor with a suitable choice of conveyor belts in terms of material and surface structure is perfectly suitable for conveying veneer strips of all kinds together with the spacers carried by them using the propulsion force imparted solely by static friction. Because this driving force is proportionate without any special effort can be kept small, there is also no danger at any point of the conveyor that excessive forces occur which damage the veneer strips or otherwise interfere with the processing of the same.

The replacement of the previous roller conveyor with a belt conveyor also has the advantage that considerably less effort is required to set it up and operate, especially due to the elimination of the numerous shafts, bearings, rollers, slip clutches and devices for height adjustment of the counter rollers. In addition, the operating behavior of a belt conveyor is far less temperature-dependent than that of a roller conveyor of the type described, and the operational noise level is also lower with the belt conveyor.

In the loading device according to German Patent No. 1 628 970, the spacers are mounted on guide rails with rollers, the guide rails being individually closed and running in vertical planes. Each guide rail has a horizontal feed section arranged directly above the conveying plane and an inclined return section located above it, these two sections on the input side of the loading device by a deflection bend and are connected to one another at the outlet side of the loading device by a shaft section. A continuously operated elevator, which extends over the entire height of the shaft section, conveys the spacers arriving from the forward section through the shaft section upwards into the return section of the guide rail. At the end of the return section there is a blocking switching device which gradually releases the spacers stuck on the same for entry into the forward section. A mechanical scanning element is used to control the blocking switching device, which is actuated by the leading longitudinal edge of a veneer strip fed to the roller conveyor.

The spacers and the means for guiding them in an orbit can in principle be of the same design in the charging device according to the invention as in the case of that according to German Patent No. 1,628,970.

A preferred embodiment of the means mentioned, however, consists in that each guide rail has a horizontal forward section arranged immediately below the conveying plane and an inclined return section located underneath, and that these two sections on the output side of the loading device by a deflection bend and on the input side of the Loading device are connected to one another by a shaft section, wherein a lifting device is effective in the shaft section, which conveys the spacers arriving from the return section through the shaft section upwards into the forward section of the guide rail.

Although this solution concept only seems to have a reversed and mirror-image arrangement of the guide rail present in the known loading device, the proposed arrangement enables significant improvements with regard to the means for returning the spacers to the lead section, which are not realized in the known solution to let.

An advantageous embodiment in this regard is that a step-by-step lifting device is provided at the lower end of the shaft section, which is controlled by the supply of the veneer strips and which detects the spacers arriving from the return section and conveys them into the shaft section, so that with each step of the lifting device in each case the uppermost one of the spacers stacked one above the other in the shaft section reaches the lead section. On the one hand, this eliminates the locking switch device previously required. On the other hand, the proposed lifting device takes up much less space than the elevator previously used according to the prior art.

The lifting device can have a star wheel which grips the spacers and which, e.g. the spacers captured on their rollers. If each spacer, as in the known loading device described, has two pairs of rollers arranged one behind the other in the web direction, the star wheel is preferably designed such that it jointly detects the rear pair of rollers of a spacer and the front pair of rollers of the immediately following spacer.

The lifting device can have a ratchet gearbox, for the operation of which, for example, a pneumatic or hydraulic working cylinder is provided.

The operation of the lifting device is advantageously controlled by an individually assigned light barrier which scans the running longitudinal edge of each veneer strip picked up by the accumulation conveyor with a light beam running perpendicular to the conveying plane. The optical scanning, in contrast to the mechanical scanning, prevents the conveyor operation, which is based on a relatively low driving force, from being impaired and possible damage to the veneer strips.

In a similar way to the known guide rail, the end region of the forward section of the guide rail can be formed by a sloping section intended for the spacers to exit the conveying plane be at the end of which the spacers disengage from the veneer strips. It is thereby achieved that the spacers assume an invariable angular position with respect to the conveying plane during their gradual withdrawal from the conveying plane, in order to avoid uncontrollable movements of the veneer strips in the vertical direction. For the same reason, it would be expedient if the spacers were as perpendicular as possible to the conveying plane both in the area of the horizontal part of the forward section and in the sloping section, so that the stop surfaces of the spacers always press essentially perpendicularly against the longitudinal edges of the veneer strips. In order to at least approximately achieve this ideal case despite the change in direction in the guideway, it is proposed that the spacers protrude from it at an angle of incidence which deviates from the perpendicular to their guideway, this angle of incidence being selected such that the angular position of the spacers with respect to the conveying plane in the two areas mentioned at the respective interface with the conveyor level deviate approximately to the same extent from the perpendicular to the conveyor level. If the spacers have wedge-shaped stop surfaces, as in the known loading device, because the wedge shape facilitates the withdrawal of the spacers from the gap between the jammed veneer strips, the rule mentioned can only be reasonably observed for one of the two stop surfaces be, ie in the horizontal area, the rear and in the oblique area, the front stop surface can run at least approximately perpendicular to the conveying plane.

When producing an endless veneer web, which is cut into veneer sheets of the desired length in a later operation, the jam of the veneer strips in the loading device is formed solely because of the higher speed of the conveying means in the loading device compared to that in the veneer splicing machine, the ratio of which e.g. Can be 2: 1. However, there is also the possibility of producing incoherent veneer sheets by jamming a number of veneer strips, which together form a veneer sheet of the desired length, in the loading device and feeding it as a separate package to the veneer splicing machine. For this purpose, a locking device can be provided at the end of the leading section of the guide rail with a stop movable in the guide track of the spacers for stopping the veneer strips in order to interrupt the veneer track. This locking device is preferably effective in the region of the sloping partial section of the guide rail.

Under certain circumstances, especially for the processing of thicker veneer strips or those with strong warping, it may be expedient to take measures to ensure that the veneer strips are already transferred to the veneer splicing machine to bring it as flat as possible. In addition, there may be a need to increase the propulsive force at the transfer point in view of the relatively low propulsive force of the belt conveyor, ie to promote the veneer strips with an increased propulsive force that is increased by the static friction. For this purpose, holding-down devices which cooperate with the conveyor belts can be provided at the end of the conveyor line and press the veneer strips to be delivered to the veneer splicing machine against the conveyor plane from above and bring about an increased advance thereof. An embodiment in this regard can consist, for example, in that each hold-down device has a counter-pressure roller without self-drive, which is aligned with the end-side deflection roller of the respective conveyor belt and around which a flat belt tapering at an acute angle to the conveyor plane is guided.

Conveniently, guiding rulers opposite the conveyor belts are arranged above the conveyor level, which extend over at least part of the conveyor section. These guide rulers are of course to be arranged in terms of their height so that the plane formed by their slideways lies below that which is formed by the tips of the spacers located in the conveying plane, so that the spacers are always gripped by the veneer strips, in particular also then when the veneer strips due to warping are partially arched up to the guide rulers and slide along them.

As tests have shown, it is easily possible to keep the overall frictional forces on the guide rails and guide rulers within permissible limits, so that the belt conveyor ensures that the veneer strips are properly propelled.

Fig. 1, 2 und 3

Frontansicht, Grundriss und eine Seitenansicht der Beschickungseinrichtung;

Fig. 4

den Förderbandantrieb;

Fig. 5

eine der je einem Förderband zugeordneten Vorrichtungen zum Betrieb der Abstandhalter und zur Niederhaltung der Furnierstreifen, in grösserem Massstab;

Fig. 6

einen Querschnitt durch die Führungsschiene für die Abstandhalter;

Fig. 7

das hintere Ende der Führungsschiene mit der Arretiervorrichtung;

Fig. 8

das vordere Ende der Führungsschiene mit der Hebevorrichtung;

Fig. 9

einen Horizontalschnitt durch die Hebevorrichtung nach der Linie IX-IX in Fig. 8; und

Fig. 10

einen Vertikalschnitt nach der Linie X-X in Fig. 9.

An exemplary embodiment of the invention is shown in the accompanying drawings, in which:

1, 2 and 3

Front view, floor plan and a side view of the loading device;

Fig. 4

the conveyor belt drive;

Fig. 5

one of the devices assigned to a conveyor belt for operating the spacers and for holding down the veneer strips, on a larger scale;

Fig. 6

a cross section through the guide rail for the spacers;

Fig. 7

the rear end of the guide rail with the locking device;

Fig. 8

the front end of the guide rail with the lifting device;

Fig. 9

a horizontal section through the lifting device along the line IX-IX in Fig. 8; and

Fig. 10

a vertical section along the line XX in Fig. 9th

The loading device shown in FIGS. 1 to 3 rests on a mobile underframe 1, which consists of different frame parts 2 to 5 and a pair of supports 6 and 7 on both sides as well as connecting parts, not specified. At the lower ends of the supports 6, 7, rollers 8 are mounted, with which the loading device can be moved up to the veneer splicing machine (not shown) on rails 9 anchored in the floor. The loading device can be blocked in the desired position with a locking device 10. Near the rear of the loading device, a yoke beam 11 is mounted above the base frame 1, which bears the hold-down devices described later and a control device 13 on a boom 12 and to which a switchgear cabinet 14 is attached on the side.

The loading device is equipped with a belt conveyor which works as a accumulation conveyor and which has a plurality of conveyor belts 15 which serve as supporting members for the veneer strips, the work in parallel tracks distributed over the width of the loading device and move the individually supplied veneer strips transversely to their longitudinal extension in a horizontal path in the conveying direction indicated by arrow 16 solely on account of the static friction. The conveyor belts 15 slide on a support plate 17 made of sheet metal, which extends over the entire width and from the front to close to the rear of the loading device, openings 18 being provided in the support plate 17 for the passage of the conveyor belts 15 on the input side of the belt conveyor are. As can only be seen from FIG. 1, the slideways 19 for the conveyor belts 15 can be offset upwards from the support plate 17. Such offset slideways can also, viewed in the conveying direction 16, extend over the entire length of the support plate 17, so that the veneer strips placed on the front side of the loading device on the support plate 17 are supported only on these slideways.

In Fig. 2, part of the support plate 17 and the yoke beam 11 is cut away in order to make the conveyor belt drive more visible. Each conveyor belt 15 wraps around a front drive roller 20, a rear deflection roller 21 and a tension roller 22, as is most clearly shown in FIG. 4. The drive rollers 20 of all conveyor belts 15 sit on a continuous drive shaft 23, which extends over the entire width of the loading device, and a common drive motor 24 drives the drive shaft 23 via a transmission belt 25.

The loading device has a plurality of devices 26, which are the same among themselves, for the operation of spacers 27, which each circulate in an orbit and intervene along the conveyor path alongside the conveyor tracks between the individual veneer strips and are carried by the latter. This is done with the purpose of keeping the veneer strips, which are provided with a heat-activatable adhesive, apart on their longitudinal edges during the loading process. These devices 26 are arranged below the conveying plane and each have a self-contained guide rail 28 which extends in a vertical plane and on which the spacers 27 are freely movable in a manner known per se with rollers 29. Fig. 5 shows such a device on a larger scale, while details thereof are shown in Figs. 6 to 10.

The spacers 27, which, for the reasons mentioned above, protrude from it at an angle of attack that deviates from the perpendicular to their guideway, have four rollers 29 arranged one behind the other in pairs. 6, the guide rail 28 is designed such that it encompasses the rollers 29 on the outside thereof. It consists of two halves 30 and 31 along their entire length, which are connected to one another by spacers 32. Regarding the course of the path 5, the guide rail 28 according to FIG. 5 has a horizontal forward section 33 arranged directly below the conveying plane and an inclined return section 34 located below it. These two sections 33, 34 are connected to one another on the outlet side of the loading device by a deflection bend 35 and on the inlet side thereof by a shaft section 36. At the lower end of the shaft section 36, a step-by-step lifting device 38 is provided in the center of a further deflection bend 37, which detects the spacers 27 arriving from the return section 34 and conveys them into the shaft section 36, so that with each step of the lifting device 38 the uppermost one in each case Shaft section 36 reaches spacer 27 stacked one on top of the other in the forward section 33.

The lifting device 38 has a two-part star wheel 39 with four grippers 40, which grip the spacers 27 on their rollers 29, namely together the rear rollers of a spacer and the front rollers of an immediately following spacer, so that the spacers 27 during transfer stay in contact in the shaft section 36. To actuate the star wheel 39, the lifting device 38 has a ratchet gear mechanism, which consists of a ratchet wheel 41, a ratchet pawl 42 and a resilient pawl 43. The pawl 42 is in a rotatable around the ratchet 41 Switching ring 44 is mounted displaceably and presses on the switching wheel 41 under the action of a spring 45. A pushing rod 47 is articulated on the switching ring 44 about the axis 46 and is connected to the push rod 48 of a pneumatic or hydraulic working cylinder 49 for operating the lifting device 38.

The operation of the lifting device 38 is controlled by a light barrier 50 which is individually assigned to it and which scans the longitudinal edge of each veneer strip picked up by the respective conveyor belt 15 with a light beam running perpendicular to the conveying plane. The arrangement is such that the lifting device 38 is advanced by one step with each scanning pulse of the light barrier 50 and thus a spacer 27 is pushed into the leading section 33 of the guide rail 28 against the rear longitudinal edge of the scanned veneer strip.

The end region of the forward section 33 of the guide rail 28 forms a sloping partial section 51, which is intended for the outlet of the spacers 27 from the conveying plane. Towards the end of this section 51, the spacers 27 disengage from the veneer strips. The angle of attack of the spacers is selected as a function of the angle of inclination of the inclined section 51 so that the angular position of the spacers 27 in the horizontal lead section 33 and in the inclined section 51 is approximately the same Dimension deviates from the vertical to the conveyor level. With an inclination angle of 15 °, an angle of attack of 10 ° has proven to be advantageous if the spacers 27, as in the present example, are wedge-shaped.

As can be seen from FIG. 5 and more clearly from FIG. 7, at the end of the forward section 33 of the guide rail 28 there is a locking device 52 which is effective in the sloping section 51 and is provided for stopping the veneer strips in order to interrupt the veneer web. This locking device 52 has a stop 54 which can be pivoted about the axis 53 and which can be moved into the guideway of the spacers 27. To operate the stop 54, a working cylinder 55 is provided, which is articulated on the one hand on the stop 54 and on the other hand on a fixed tab 56.

So that the spacers 27 have a free path along the conveying path, corresponding longitudinal slots 57 are provided in the support plate 17 (FIG. 2).

At the end of the conveyor line, holding-down devices 58 which cooperate with the conveyor belts 15 are also provided, which press the veneer strips to be delivered to the veneer splicing machine against the conveyor plane from above and bring about increased propulsion thereof. These hold-down devices 58 are mounted on the yoke beam 11 and have one counter pressure roller 59 aligned on the end deflection roller 21 of the respective conveyor belt 15 without self-propulsion. The counterpressure roller 59 is freely rotatably mounted on the free end of a lever 61 which can be pivoted about the axis 60 and on which the force of a working cylinder 62 which generates the counterpressure is effective. An endless flat belt 64 is guided around the counterpressure roller 59 and a further roller 63, which can be freely rotated on the axis 60 and which runs at an acute angle to the conveying plane and facilitates the entry of the veneer strips between the rollers 21 and 59.

Finally, a height-adjustable guide ruler 65 is attached to each hold-down device 58, which lies opposite the relevant conveyor belt 15 above the conveying plane and which extends over part of the conveying path to the effective area of the hold-down device 58.

Claims (16)

1. Charging mechanism for a machine for assembling veneer strips into a veneer length by mutual gluing together of the veneer strips on their longitudinal edges, having a retarding conveyor which advances the individually supplied veneer strips transversely to their longitudinal extent in a horizontal path and the conveying means of which operate in a plurality of parallel tracks distributed over the width of the charging mechanism, and having spacers which are guided in a freely movable manner in the direction of conveyance and circulate in circular paths and which, along the conveying section next to the conveying tracks, reach in between the individual veneer strips and are carried along by the latter, characterized in that the retarding conveyor is configured as a belt conveyor exhibiting a plurality of conveyor belts (15) which slide on a supporting plate (17) and act as supporting members for a multiplicity of veneer strips and which drive the veneer strips forward on the retarding section solely on the basis of static friction, and in that the guide means (28) forming the circular paths of the spacers (27) are disposed beneath the plane of conveyance.
2. Charging mechanism according to Claim 1, in which the spacers (27) are mounted by rollers (29) on guide rails (28), the guide rails being individually self-enclosed and running in vertical planes, characterized in that each guide rail (28) exhibits a horizontal forward-travel segment (33) disposed directly beneath the plane of conveyance and a thereunder located, obliquely sloping return-travel segment (34), and in that these two segments are joined together on the delivery side of the charging mechanism by a deflecting guard and on the feed side of the charging mechanism by a shaft segment, a lifting device being operative in the shaft segment (38), which lifting device conveys the spacers (27) arriving out of the return-travel segment (34) upwards through the shaft segment (36) into the forward-travel segment (33) of the guide rail (28).
3. Charging mechanism according to Claim 2, characterized in that at the lower end of the shaft segment (36) there is provided a progressively working lifting device (38), which is controlled by the supply of the veneer strips and which grasps the spacers (27) arriving out of the return-travel segment (34) and transports them into the shaft segment (36), so that, upon each progression of the lifting device (38), the uppermost, in each case, of the spacers (27) stacked one on top of the other in the shaft segment (36) reaches the forward-travel segment (33).
4. Charging mechanism according to Claim 3, characterized in that the lifting device (38) exhibits a star wheel (39) which grasps the spacers (27).
5. Charging mechanism according to Claim 4, characterized in that the star wheel (39) grasps the spacers (27) by their rollers (29).
6. Charging mechanism according to Claim 5, in which each spacer (27) exhibits two roller pairs disposed one behind the other in the path direction, characterized in that the star wheel (39) is configured such that it grasps jointly, in each case, the rear roller pair of one spacer (27) and the front roller pair of the directly following spacer (27).
7. Charging mechanism according to one of Claims 3 to 6, characterized in that the lifting device (38) exhibits a ratchet gearing (41-46).
8. Charging mechanism according to Claim 7, characterized in that, for the operation of the ratchet gearing (41-46), a pneumatic or hydraulic working cylinder (49) is provided.
9. Charging mechanism according to one of Claims 3 to 8, characterized in that the operation of the lifting device (38) is controlled by a light barrier (50), which is assigned to the said lifting device and which, with a light beam running perpendicular to the plane of conveyance, scans the trailing longitudinal edge of each veneer strip received by the retarding conveyor.
10. Charging mechanism according to Claim 2, characterized in that the end region of the forward-travel segment (33) of the guide rail (28) is formed by an obliquely sloping part segment (51), which is intended for the departure of the spacers (27) from the plane of conveyance and towards the end of which the spacers disengage from the veneer strips.
11. Charging mechanism according to Claim 10, characterized in that the spacers (27) protrude from their guide path at a setting angle deviating from the perpendicular to the said guide path, this setting angle being chosen such that the angular position of the spacers (27) in relation to the plane of conveyance deviates, in the region of the horizontal part of the forward-travel segment (33) of the guide rail (28) on the one hand and in the region of the obliquely sloping part segment (51) at the end of the forward-travel segment (33) on the other hand, at the respective point of intersection with the plane of conveyance, approximately in the same measure from the perpendicular to the plane of conveyance.
12. Charging mechanism according to Claim 3, characterized in that at the end of the forward-travel segment (33) of the guide rail (28) there is provided an arresting device (52) having a stop (54), which can be moved into the guide path of the spacers (27), for halting the veneer strips for the purpose of interrupting the veneer length.
13. Charging mechanism according to Claims 10 and 12, characterized in that the arresting device (52) is operative in the region of the obliquely sloping part segment (51) of the guide rail (28).
14. Charging mechanism according to one of Claims 1 to 13, characterized in that at the end of the conveying section there are provided hold-down devices (58), which work together with the conveyor belts (15) and which press the veneer strips, which are to be delivered to the veneer assembling machine, from above towards the plane of conveyance and bring about an enhanced propulsion of the said veneer strips.
15. Charging mechanism according to Claim 14, characterized in that each hold-down device (58) exhibits a counter-pressure roller (59) without a dedicated drive, which counter-pressure roller is aligned to the end-side deflection roller (21) of the respective conveyor belt (15) and around which there is guided a flat belt (64) running up to the plane of conveyance at an acute angle.
16. Charging mechanism according to one of Claims 1 to 15, characterized in that above the plane of conveyance there are disposed guide rules (65), which lie opposite the conveyor belts (15) and extend over at least part of the conveying section.

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