Device for feeding boards to crosscut saws

A device for supplying boards to crosscut saws has a feeding device and a transverse transport unit arranged downstream of the feeding device. Several loading planes are arranged downstream of the transverse transport unit and positioned at different levels. The boards are supplied on the loading planes to a crosscut saw, respectively. The transverse transport unit is adjustable relative to the loading planes about an axis that is transverse to a transport direction of the boards on the transverse transport unit. A stop is adjustably arranged in the transport path of the boards on the transverse transport unit, wherein the stop, without sensing the boards, is adjustable exclusively by a control unit of the device. When the transverse transport unit is being adjusted into a new position relative to the loading planes, the stop prevents further transport of the boards to the loading planes, respectively.

BACKGROUND OF THE INVENTION

The invention relates to a device for feeding boards to crosscut saws comprising at least one feeding device and at least one transverse transport unit arranged downstream which transverse transport unit has arranged downstream thereof at least two loading planes, positioned at different levels on which the boards are supplied to at least one crosscut saw, respectively, and which transverse transport unit is adjustable about an axis transverse to the feeding direction of the boards relative to the respective loading plane.

In wood processing it is known to first scan boards or pieces of wood to be sawed by means of a stationary scanning unit in a continuous process to detect in this way e.g. flaws in the boards that must be removed during further processing. The board data acquired by the scanning unit are optimized by software and a cutting list is computed for each board. Based on the cutting list, the scanned board is then processed by the crosscut saws. After the scanning process, the boards are received by a mechanizing device wherein at the transfer station the proper cutting list is assigned to the respective board. The boards with assigned cutting list are supplied to one or several cross-cut saws. After the scanning process, the boards, aligned with one end face, are transferred from a feeding device in the form of a wide roller table with cam chains or a wide transport belt with transport compartments on top to a downstream transverse transport unit. At this location, the boards are individually received by the transverse transport unit and individually held in place by means of so-called floating pawls. Floating pawls are pneumatically controlled stop element rows that are actuated by signals of the device control. This signal is generated by one or several photo cells when the board is in the correct position. After receiving a certain number of boards, preferably between five and ten boards, the transverse transport unit is pivoted such that the boards are transferred to the downstream loading plane on which they are transported to the crosscut saw.

Often two loading planes arranged above one another are provided and they each have a crosscut saw correlated therewith. It is also possible to provide downstream a second transverse transport unit which is pivotable and by means of which further loading planes that have correlated therewith further crosscut saws, are accessed. The control in regard to the position of the boards on the transverse transport unit and the distribution of the boards onto the respective loading planes are realized by means of photo cells and the control unit of the device. This device is however prone to failure as regards follow-up of the boards. It can happen that a board is supplied to a crosscut saw and the electronic board data (cutting list) of a different board is transmitted to the control unit of the crosscut saw. This leads to faulty crosscut results until the feeding error has been recognized by control mechanisms and the device is stopped. Subsequently, the device must be emptied or processing must be continued until the device is empty; this is disruptive to the production process and decreases the performance.

SUMMARY OF THE INVENTION

It is an object of the invention to design the device of the aforementioned kind in such a way that the boards during their transport to the crosscut saw can be monitored properly and that at the crosscut saw the boards and the correlated cutting list or board data are present.

This object is solved in connection with the device according to the invention in that in the transport path of the boards on the transverse transport unit at least one stop is adjustable which stop is adjustable or positionable, without scanning the boards, exclusively by means of a control unit and which stop, during adjustment of the transverse transport unit, prevents further transport of the boards onto the loading plane, respectively.

In the device according to the invention the boards, downstream of the feeding device, are reliably distributed by means of the transverse transport unit onto the desired loading plane without this requiring photo cells and other sensors for monitoring the boards. When the transverse transport unit is to be adjusted to a different loading plane, a stop is adjusted in the transport path of the boards and the boards coming from the feeding device will come to rest at this stop. During the time in which the transverse transport unit is adjusted to the new loading plane, the boards remain on the transverse transport unit. This mechanical means ensures that the boards are reliably supplied to the predetermined loading plane and the predetermined crosscut saws.

The stop at the transfer area between the feeding device and the transverse transport unit is moved into the transport path of the boards.

The stop is moveable from the transfer area to the other end of the transverse transport unit.

Upon reaching the other end of the transverse transport unit, the stop is stopped and the transverse transport unit is adjusted into a new position about the axis.

The stop is part of a circulating cam chain.

The transverse transport unit has endless circulating belts.

The cam chain is arranged between two endless circulating belts.

The cam chain is arranged adjacent to an endless circulating belt.

The belts and the cam chain have separate drives.

The stop emerges from the support plane of the feeding device in the area of a spacer, preferably of the last spacer before the deflection location.

Further features of the invention result from the additional claims, the description, and the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The device comprises a feeding device1for boards2that are supplied to a transverse transport unit3arranged downstream of the feeding device. The feeding device1can be embodied as a wide roller table with cam chain or as a wide transport belt. In the illustrated embodied the feeding device1is a wide roller table that has flat spacers5positioned transverse to its transport direction4for separating neighboring boards2from one another. The wide roller table is driven. The boards2are transported by means of an upstream conveying unit (not illustrated) in their longitudinal direction into the space between the spacers5. The conveying unit is formed, for example, by advancing rollers that rest on the boards2and transport them in the longitudinal direction onto the feeding device1. The boards2have been scanned prior to this by so-called continuous scanners that are arranged stationarily and acquire data of the boards2in a way known in the art. A data set is produced for the acquired board data and based on this set crosscut saws (not illustrated) downstream of the device will saw the boards2.

In the last compartment6of the feeding device1before transfer onto the transverse transport unit3, it is checked by means of a sensor, preferably a photo cell (not illustrated), whether the boards2are aligned with their end face7relative to a terminal zero line. Parallel to the transport of boards2the correlated data sets are transferred to the appropriate saws. The boards2are transferred to the transverse transport unit3that is adjusted relative to the feeding device1in accordance with the cutting list. As can be seen inFIG. 1, the transverse transport unit3can be adjusted to various positions about axis8that is positioned transversely to the transport direction4. As an example, four pivot positions I to IV of the transverse transport unit3are illustrated inFIG. 1. The pivot axis8is located in the transfer area9between the feeding device1and the transverse transport unit3. By means of the transverse transport unit3the pieces of wood2are transferred to loading planes (not illustrated) that supply the boards to the downstream crosscut saws. In the illustrated embodiment, the transverse transport unit3can be pivoted into four different slanted positions. Each of these slanted positions has correlated therewith a crosscut saw in which the pieces of wood2are cut in accordance with their data set.

The transverse transport unit3is comprised of parallel adjacently positioned endless circulating belts10driven by a drive with which the boards2are transported in the transport direction11(FIG. 1). Parallel to each belt10a cam chain CC (FIG. 4) is provided that has one or several cams12. InFIGS. 1 and 2only one cam12is illustrated in an exemplary fashion. With the aid ofFIG. 3, the effect of this cam (stop)12controlled by the control unit will be explained in detail. The driving action of the cam chain with the cams (stops)12is realized advantageously by means of a servo motor. The drive of the cam chain can also be realized by means of a frequency converter or a three-phase motor with brake. For stroke adjustment of the transverse transport unit3a motor drive, preferably a servo motor, is used. It is however also possible to pivot the transverse transport unit3by means of pneumatic or hydraulic devices. The transport belts10of the transverse transport unit3with the correlated deflection rollers are supported on a common frame (not illustrated) that is adjustable by means of the drive with regard to its vertical position.

Appropriate loading planes LP, depending on the slanted position I, II, III, IV, adjoin the end of the transverse transport unit facing away from the feeding device1(seeFIG. 1); on the loading planes LP, the pieces of wood are supplied to the crosscut saws CS, respectively.

Based onFIG. 3the function of a cam chain will be explained. They each have two cams12that project past the belts10of the transverse transport unit3. First the boards2are transferred from the feeding device1to the transverse transport unit3that is in one of the pivot positions I to IV shown in exemplary fashion inFIG. 1. The cams12are arranged in accordance with the central illustration ofFIG. 3. When enough boards2have been supplied sequentially to the corresponding loading plane and the loading plane is to be changed, the cam chains are driven such that the cam12is moved in the transfer area9between the feeding device1and the transverse transport unit3into the transport path of the boards2at the rearward end of the transverse transport unit3viewed in the transport direction11. The movement path of the cam12is illustrated inFIG. 2. The drives of the feeding device1and of the cam chain are adjusted relative to one another such that the cam12, viewed in the direction of axis8, emerges in the area of the last spacer5before the deflection location out of the support plane13of the feeding device1. The position of the cams12according toFIG. 2corresponds to the lower illustration inFIG. 3. The other cam12of each cam chain is positioned in the area of the lower run of the belts10. At the cam12that is in the blocking position the boards2that are supplied by the feeding device1are collected. The boards2that are in front of the cam12in the transport direction11can still be transported onto the loading plane. The cam12moves with the belts10until it reaches the leading end of the transverse transport unit3in the transport direction11(upper illustration inFIG. 3). The camshafts and thus the cams12are stopped and the transverse transport unit3is pivoted about axis8into a new position in order to supply a different loading plane with boards2. The trailing cam12of the cam chain in the transport direction11is positioned at the lower run of the belts10so that the boards2are still transported from the feeding device1onto the transverse transport unit3. In this way, the boards2are collected so as to rest against one another at the stopped cam12. As soon as the transverse transport unit3has been pivoted accordingly, the cam chains are driven and the cam12is moved into the area of the lower run of the belts10. The boards2are thus released and are transported onto the new loading plane. The position of the cams12immediately after release of the boards2is illustrated in the central illustration ofFIG. 3. The other cam12is in a position so as not to impair the supply of boards2from the feeding device1onto the transverse transport unit3. This position of the cams12corresponds to the basic position of the cam chain so that the belts10of the transverse transport unit3can receive the boards2from the feeding device1and transfer them onto the loading plane. In the lower illustration ofFIG. 3, the left cam12is illustrated that is moved by driving the corresponding cam chain in the transport direction11toward its blocking position (upper illustration inFIG. 3). During the movement of the cam12into this blocking position the boards2supplied by the feeding device1are collected at its backside. Once the cam12has reached the blocking position in accordance with the upper illustration ofFIG. 3, the drive of the cam chains is stopped and the transverse transport unit3is now pivoted about axis8to a new position in order to supply a different loading plane with boards2. Once the transverse transport unit3has reached the new pivot position, the cam chains are driven and the cams12are accordingly moved into the release position (central illustration ofFIG. 3) so that the boards2are supplied to a new loading plane.

When using this device, after transfer of the electronic cutting list to the crosscut saws photo cells or other sensors have no longer any effect on the distribution of the boards2so that errors in the subsequent cross-cutting work are excluded. The boards2are reliably supplied in the afore described way by means of the transverse transport unit3to the predetermined loading planes and thus also to the correct crosscut saws. This mechanical solution enables a simple constructive design of the device and provides reliable operation.