Patent Application
20080041494
This application claims priority under Section 119 to Finnish Patent Application No. 20060529 which was filed on May 31, 2006.
The invention relates to a longitudinal conveyor for feeding a woodsawn cant in a lengthwise direction of the cant to an edging saw, the longitudinal conveyor comprising: a fixed frame structure; an underside conveyor chain, having a top surface adapted for contact with the external surface of cants; and an upper counter conveyor, having movable members with an external surface adapted for contact with the external surface of cants, as well as springy force members, allowing for an elastic displacement of the movable members away from the top surface of said conveyor chain and at the same time producing a press force towards the top surface of said conveyor chain.
In the process of cutting a log of timber for planks, boards, laths or the like, the log is generally first dressed, i.e. it is sawn for at least two, but usually four flat and pairwise parallel outer faces which, in order to achieve a good sawing yield, do not, however, normally coincide with each other but, instead, the log is left with a somewhat roundish surface segment. Guided by these outer faces, the log is then sawn to produce for example cant boards or cant planks, which include or may include some so-called wane edge. The “wane edge” implies that the edges of a sawn-off cant are not, over the entire height thereof, perpendicular to the cant's top surface and bottom surface planes. If the cants were sawn off a log straight away, without producing the above-mentioned flat outer faces, every cant would end up with a wane edge. Next, the cutting process thus includes the edging of cant planks or cant boards in an “edger” or an edging saw for the cant, the board or plank having its edges dressed and trimmed by removing the cant's wane edges. Subsequently in this specification, the concept “cant” is used to stand for an undressed plank, board or lath sawn off a tree trunk, because in most cases the lateral dimensions constitute the only factor distinguishing these from each other. In any event, the cant is subjected to further longitudinal sawing operations. Guiding such a cant to a further sawing process presents problems since, as a result of the wane edge, the cants are perhaps not consistent in width, nor are the edges even straight.
Patent publication U.S. Pat. No. 5,785,102 concerns an edger of this type, but in actual fact it describes a positioning apparatus for an elongated cant, whereby cants are conveyed transversely to a position designated therefor in the process of feeding the cants into an edger. In general, the described apparatus comprises: a frame structure; a conveying module for transversely conveying the cant along a substantially straight path; a scanning module located along the path for optically scanning the morphology of the cant and providing morphology data; a computer module linked to the scanning means for analyzing the morphology data and calculating a longitudinal preferred infeed line for said cant; and a positioning means located further along the path for transversely positioning the cant in a colinear relationship with the preferred infeed line for said cant. More specifically, the positioning means comprises a plurality of movable pinching members for correctly aligning the cants, whereafter the positioned cants are longitudinally advanced on a longitudinal conveyor into the edging device. In the cited publication, this longitudinal conveyor is of a conventional type, consisting of a lower double-chain traveling along a fixed chain slot and carrying the cants on top of it, and upper feeding rollers pressing the cants against the double-chain for a firm frictional contact between the double-chain and the cants.
The commonly employed longitudinal conveyors, which consist of a lower conveyor chain and a plurality of spring-loaded overhead press rollers, present a problem that, at some point of the conveying path, the cants may be dislodged sideways, i.e. transversely to the length of a cant, either completely or partially. As a result of this, the wane edge is not removed completely by the edger from one edge of the cant and some full-edged portion shall be unnecessarily removed from the other. This, in turn, increases loss and incurs also other extra costs in terms of inspections and possible re-sawing operations. Another problem involved in the use of these press rollers is the necessity to lift each roller just before the leading end of a moving cant reaches a position in line with the roller, since otherwise the board end collides with the roller and may halt completely, and then to depress the roller quickly enough for having it pinch the cant against the conveyor chain before the board has passed by. Such a control requires massive and extensive control technology, which again adds to fault sensitivity and costs.
It is an objective of the invention to provide such a longitudinal conveyor for feeding a woodsawn cant in a lengthwise direction of the cant to an edging saw or other similar finishing saw, which, after the completed positioning of cants, prevents as effectively as possible an undesired shift or displacement of the discussed cants in this conveyor in a direction transverse to the length thereof. A second objective of the invention is to provide this type of longitudinal conveyor, which would not require an electronic or the like control system to control various sections of the conveyor according to the advancement of a cant.
The above problems can be eliminated and the above objectives accomplished by an apparatus of the invention. Such an apparatus is a longitudinal conveyor for feeding a woodsawn cant in a lengthwise direction of the cant to an edging saw, the longitudinal conveyor comprising a fixed frame structure, an underside conveyor chain, having a top surface adapted for contact with the external surface of cants, and an upper counter conveyor, having movable members with an external surface adapted for contact with the external surface of cants, as well as springy force members, allowing for an elastic displacement of the movable members away from the top surface of the conveyor chain and being capable of producing a press force towards the top surface of the conveyor chain, wherein the movable members comprise an upperside conveyor belt and at least two drive rolls spaced from each other by a distance co-directional with the conveyor chain, the upperside conveyor belt proceeding around the drive rolls to form a loop, which is co-directional with the conveyor chain, includes a bottom section with its downward surface as well as a top section, the springy force members comprise at least three press units urged with the elastic press force to act against the bottom section of the upperside conveyor belt and towards the top surface of the conveyor chain, and the upper counter conveyor further comprises a motor coupled with at least one drive roll, whereupon the upperside conveyor belt is movable co-directionally with the conveyor chain.
The invention will now be described in detail with reference to the accompanying drawings.
Thus, the longitudinal conveyor is used for feeding woodsawn semifinished planks or boards or the like, typically cants 9 in a lengthwise direction L1 of the cants to an edging saw 30, wherein the cants are stripped of wane edges 29, i.e. edge portions 29 of the cant slanted with respect to a top surface 31Y and a bottom surface 31A and often unequal in width, along parallel cutting lines 32 as can be appreciated on the basis of
The underside conveyor chain 33 extends around rolls, not shown in the figures, to establish a loop and the loop's upper run forms the planar top surface 3y, against which the cant's 9 bottom surface 31A settles for the duration of transport. The underside conveyor chain 33 can be of any conventional or new appropriate type and hence not explained here in further detail. Secondly, the longitudinal conveyor comprises an upper counter conveyor 10, having movable members with an external surface adapted for contact with the external surface of cants, thus, in this case with the cants' top surface 31Y, as well as springy force members 11, allowing for an elastic displacement of these movable members away from the top surface 3y of the conveyor chain 33, yet capable of producing a press force Fp towards the top surface of said conveyor chain. The cants 9 are delivered in between the underside conveyor chain 33 and the upper counter conveyor 10, of which the underside conveyor chain does not flex in a vertical direction H1=H2, while the upper counter conveyor 10 flexes in the vertical direction H1=H2 and generates the press force Fp, whereby the cants 9 are pressed against the conveyor chain 33. Said vertical direction is perpendicular to a conveying direction M and parallel to the thickness S of a cant. The longitudinal conveyor comprises a fixed frame structure 41, having at least the upper counter conveyor 10, but generally also the underside conveyor chain 33 attached thereto.
According to the invention, the above-mentioned movable members of the upper counter conveyor 10 comprise an upperside conveyor belt 34 and at least two drive rolls 5a, 5b spaced from each other by a distance L2 co-directional with the conveyor chain 33, the upperside conveyor belt 34 extending around said drive rolls 5a and 5b to establish a loop co-directional with the conveyor chain. This loop i.e. the upperside conveyor belt 34 includes a bottom section 12 with its bottom surface 4a, as well as a top section 13. The bottom section 12 has its bottom surface 4a located opposite to the underside conveyor chain's 33 top surface 3y in such a way that, when there is no cant present between the conveyor chain's top surface 3y and the conveyor belt's bottom surface 4a, a distance V between the top surface 3y and the bottom surface 4a is less than the thickness S of a cant, whereby the distance V can be a zero or approach a zero or a contact, as can be appreciated from
In particular, according to the invention, the conveyor belt 34 is a self-guided cogged V-belt, wherein an outer loop surface 14, which constitutes said bottom surface 4a, is a smooth or rough, flat friction surface as can be seen in
Further according to the invention, the above-mentioned press units 6a, 6b, 6c . . . of the springy force members 11 comprise a bottom sliding surface 8, against which the inner surface 15 of the conveyor belt's 34 loop is capable of sliding and which is provided with a groove(s) 28a or a rib/ribs 28b, which is/are co-directional with the distance L2 or parallel to the conveying direction M and consistent with the wedge rib/ribs or wedge groove/grooves of the conveyor belt, as visualized in
The longitudinal conveyor 1 of the invention includes a special main girder 40, which is mounted on the fixed frame structure 41 in a subsequently described manner. The main girder 40 is an elongated rigid beam structure, having its length extending in the conveying direction M of the underside conveyor chain 33 and of course in that of the upperside conveyor belt 34. The at least two drive rolls 5a, 5b of the conveyor belt 34 are bearing-mounted on this main girder at the distance L2 from each other, i.e. on the forward end of the main girder and on the rearward end of the main girder. If the configuration includes more drive rolls, such as four drive rolls 5a, 5b, 5c, 5d, the outermost of those, i.e. for example the first upper drive roll 5a and the second underside drive roll 5b, are bearing-mounted on the main girder 40 at the distance L2 from each other. The other drive rolls are also bearing-mounted on the main girder, but at a slightly lesser distance from each other. It should be noted, however, that the extent of the conveyor belt's 34 bottom section 12, which carries the above-described press units 6a, 6b, 6c, 6d . . . , does not include drive rolls as the latter are preferably included in the end regions of the main girder. Thus, for example, the first upper drive roll 5a and the first lower drive roll 5c are present in the forward end region of the main girder 40 and the second upper drive roll 5d and the second lower drive roll 5b are present in the rearward end region of the main girder 40. The forward end and the rearward end are after all regarded in relation to the conveying direction, the cants being supplied by the forward end and discharged by the rearward end. Hence, along the bottom section 12, the conveyor belt is for the most part only guided by means of the press units.
The springy force members 11 comprise at least one pneumatic or hydraulic cylinder assembly 19 or a mechanical spring assembly between the main girder 40 and each press unit 6, as shown in
At least one of the two drive rolls or one of the upper drive rolls 5a or 5d is coupled with the main girder by means of a tightener 25, for example by means of a horizontally working tightener, which produces a tightening force Fk. Being evenly distributed between the conveyor belt's top section 13 and bottom section 12, the tightening force creates in the conveyor belt 34 a tension force Fk/2, having a vertical component Fv=Fk/2×sin α at the front guide 21 of the foremost guide 6a, when the angle α is an angle formed between the intersection point of a vertical line for the foremost press unit's 6a back guide 22 and the underside conveyor chain's 33 top surface 3y and a connecting line for the bottom side of either the single foremost drive roll 5a or the lower drive roll 5c of the foremost drive rolls 5a, 5c and the conveyor chain's 33 top surface 3y. When said vertical component Fv is greater than a component force Ff=Fp×B/(A+B) of said press force at the front guide 21 of the foremost press unit 6a but lesser than said press force Fp, the result is that the foremost press unit's 6a leading edge rises to the same level or almost to the same level as the bottom side of the single foremost drive roll 5a or the lower drive roll 5c of the foremost drive rolls, but the foremost press unit's trailing edge remains in contact or almost in contact with the underside conveyor chain's 33 top surface 3y. This condition is depicted in
The main girder 40 is braced to the fixed frame structure 41 by pairs of levers 38 or by adjuster screws or adjuster bolts 39. If the pairs of levers 38 are used, one lever of the pair of levers on one side of the main girder and the other lever on the other side of the main girder, the pairs of levers will be of the type capable of being deflected or tilted in a plane co-directional with the conveying direction M and perpendicular to the conveyors' 33, 34 top and bottom surfaces 3y and 4a. When a deflection angle K with respect to the direction of said distance L2 and the conveying direction M is adjustable, the vertical distance H1 can be adjusted to fit the thickness S of a cant. If the adjuster screws and adjuster bolts 39 are used, which typically come also in pairs, one screw-bolt assembly on one side of the main girder and the other screw-bolt assembly on the other side of the main girder, the screw-bolt assembles will be of such a type that the effective length H2 thereof can be used for changing the elevation of the main girder in a direction perpendicular to the conveyors' 33, 34 top and bottom surfaces 3y and 4a, so this feature can also be used for setting the vertical distance H1 to fit the thickness S of a cant.
While there have been shown and described and pointed out fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. Furthermore, in the claims means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20060529 | May 2006 | FI | national |
