WO2008096043A1

WO2008096043A1 - Apparatus for conveying timber

Info

Publication number: WO2008096043A1
Application number: PCT/FI2008/050048
Authority: WO
Inventors: Arvo Nuutinen
Original assignee: Lineartec Oy
Priority date: 2007-02-07
Filing date: 2008-02-07
Publication date: 2008-08-14
Also published as: FI119471B; FI20070114A; FI20070114A0

Abstract

An apparatus for conveying elongated timber elements (6) in their crosswise position, comprising a flighted conveyor (1) in which flights (5) are supported on an endless drawing member (3), such as chain, which has been adapted to pass around two idlers (2) positioned at a distance from each other and supported to rotate substantially vertically, the flights being supported to extend outwards from the link formed by the drawing member, for conveying timber elements (6) along with the movement of the drawing member so that they are pressed between the flights. In accordance with the invention, the flighted conveyor (1) comprises successive flights (5), each of them comprising a body part (13) and, relative to the moving direction of the drawing member, a push part (14) at the front side and a stop part (15) at the back side, so that one of the push part and the stop part has been arranged to be flexible relative to the body part in the longitudinal direction of the drawing member, for pressing the timber elements (6) at their faces (7) between the push part of the latter of two successive flights and the stop part of the preceding one.

Description

APPARATUS FOR CONVEYING TIMBER

FIELD OF THE INVENTION

The invention relates to automatic processing of timber elements, specifically to conveyance of elongated timber elements with a so-called flighted conveyor .

BACKGROUND OF THE INVENTION

In the wood-processing industry, for example in the manufacture of building elements, such as rafter beams or the like, wood elements are more and more often processed automatically. This provides considerable advantages in terms of saving workforce expenses and improving the machining accuracy. One major aspect in the automatic machining of wood elements is its quick and reliable conveyance from the storage site to the machining devices, between the machining devices, and further out of the production line.

Along with the developing automation spe- cifically in the case of machining devices, providing a sufficiently high feed rate of the wood elements to the machining devices has proved to be problematic. Various automatic conveyors have been developed in order to replace manual feeding. However, the higher the conveying efficiency pursued with an automatic conveyor, the more challenging it will be to ensure reliable operation of the conveyor.

One known solution for conveying timber elements automatically is to use a so-called flighted conveyor in which the timber elements are conveyed so that they are supported by support members, or so- called flights, which are mounted to a belt, chain or the like. The flighted conveyor conveys the timber elements in their crosswise direction, which is an ad- vantageous feature for example in arrangements in which the machining means are arranged side by side on the production line for simultaneously machining the heads of an object. An example of a flighted conveyor is presented in patent US 4516675. In the solution de- scribed therein, flights designated for the front and the back side of the timber elements have been mounted in pairs to a chain which is used as a drawing device for conveying the timber elements so that they are pressed between the flights. The solution presented above comprises a number of major problems which make it practically useless in the modern production lines. To begin with, the flight structures as presented are complex. The use of a separate front and back flight makes the conveying inefficient, because successive wood objects cannot be positioned close to each other. On the other hand, to increase the conveying efficiency, the moving speed of the chain must be raised, which in turn promotes wearing and need for maintenance and makes the conveyor operation vulnerable to malfunctions. Furthermore, a high conveying speed past the machining devices complicates the machining operation itself, requiring, for example in the case of a circular saw, a blade rotation speed which may be substantially higher than the optimal rotation speed in terms of the operation of the saw. Furthermore, the publication does not disclose how the timber elements could be reliably fed to the conveyor in practice in the solution according to the figures of the publication. The fed timber elements are positioned on top of the latter flight at a high level relative to the conveying chain itself, and during feeding they are supported for a long time merely by the back flight, which increases the possibilities for incorrect motion of the objects. Another known example is a different type of conveyor developed by Koskovich Company, in which the wood elements are fed to a flighted-conveyor-type conveying device from a horizontal feeding platform. As the back flight lifts the object from below, it is at the same time supported by a separate retainer also from above until it reaches contact with the front flight as well. The apparatus enables a bit higher conveying efficiency than the arrangement in accordance with patent US 4516675, but on the other hand, the apparatus is extremely complex.

OBJECTIVE OF THE INVENTION

The objective of the invention is to provide an efficient and reliable and yet as simple as possible apparatus for automatic conveying of elongated timber elements.

SUMMARY OF THE INVENTION

The invention is characterized by what has been presented in claim 1. The apparatus of the invention for conveying elongated timber elements in their crosswise position comprises a flighted conveyor in which flights are supported on an endless drawing member, such as chain, which has been adapted to pass around two idlers posi- tioned at a distance from each other and supported so that they rotate substantially vertically, the flights being supported so that they extend outwards from the link formed by the drawing member, for conveying timber elements along with the motion of the drawing mem- ber so that they are pressed between the flights. As used herein, a timber element refers to any wood element that has been preferably so machined that it has a substantially rectangular cross-section, such as plank, board, lath or the like. The timber elements are fed to such flighted conveyor close to one idler when successive flights have become open relative to each other due to the curving path of the drawing member which moves around the idler. The tightly pressed timber elements proceed with the drawing member up to the other idler, where they are released as the flights reopen relative to each other. Since the conveyed timber elements may be several metres long, the flighted conveyor normally comprises practically two drawing members as described above, side by side and at a specific distance from each other. In accordance with the invention, the flighted conveyor comprises successive flights, each of them comprising a body part and, relative to the moving direction of the drawing member, a push part at the front side and a stop part at the back side, wherein at least one of the push part and the stop part has been arranged to be flexible in the moving direction of the drawing member, for pressing timber elements at the faces between the push part of the latter of two successive flights and the stop part of the preceding one. Unlike in the solutions according to the prior art which comprise separate front and back flights, in the solution of the invention each of the flights operates thus as a back and a front flight for the wood elements. This provides many considerable advantages. When timber elements can be conveyed in each space between the flights, it is possible to provide a substantially higher efficiency, i.e. volume of the conveyed timber elements per time unit, for the conveyor than in the known solutions. On the other hand, the dense amount of the timber elements in the longitudinal direction of the drawing member in the conveyor allows an equal conveying efficiency compared to the known solutions, yet with a considerably lower movement speed of the drawing member. In this manner, both feeding to the conveyor and discharging from the conveyor become easier, while at the same time the like- lihood of malfunctions caused by uncontrolled movements of the timber elements becomes smaller. Also machining the conveyed timber elements becomes easier as the machining devices can be controlled and the ma- chining members themselves moved at a calmer pace. Furthermore, as the moving speed decreases, also the wearing of the apparatus is reduced and the need for maintenance becomes more infrequent. The flexible movement of the push and/or stop part, or in other words adjustment of the flight thickness, enables conveyance of timber elements of varying thickness with a suitable pressing force, yet so that a change in thickness does not require adjustment of the support between the flight and the drawing member. To make the apparatus simpler, all flights of the conveyor, or at least the set of successive flights, are preferably mutually similar.

In one preferred embodiment of the invention, the stop part is supported on the body part so that it moves by a spring in the longitudinal direction of the drawing member. As the flexibility has been arranged to the stop part, the push part may be fixed relative to the body part of the flight, stabilizing the operation of the conveyor, in particular during feeding the timber elements to the flighted conveyor. On the other hand, it is possible to arrange flexibility also to the push part or to the stop and the push part both.

The distance between successive flights and the flexibility between the push and the stop part has been so adapted that timber elements with the minimum thickness of not more than 35mm and the maximum thickness of at least 50mm can be pressed between the flights. In this manner, practically all timber element thicknesses normally used for example in the roof truss industry are covered, without having to adjust the apparatus according to changes in the thickness. A flight preferably comprises, for example in the push part, a friction member for increasing the frictional force between the timber element and the flight. At the simplest, the friction member may be for example a rubber surface. The greater the frictional force between the flight and the timber element, the more secure is the flawless operation of the conveyor, particularly during the feeding step.

The flighted conveyor comprises in a pre- ferred embodiment a support member substantially at the level of the drawing member for supporting the side of a timber element against it. Firstly, as the conveyed timber elements are supported, in the extending direction of the flight, as close as possible to the level of the drawing member itself, the flight can be provided as a relatively low structure. Secondly, the closer to the drawing member the support member has been positioned, the shorter is the path of the timber elements during feeding to the conveyor on the support of merely the latter flight before being pressed between two flights, and the smaller is the likelihood of malfunctions during feeding. The support surface may be separate from the drawing member, for example a sliding surface, or it can be arranged to the drawing member itself.

The push part of the flight preferably extends to a distance of at least about 100mm from the support member measured perpendicularly relative to the longitudinal direction of the drawing member. A height of about 100mm from the support member allows the firm conveyance of timber elements which are up to 250mm wide with one and the same conveyor structure.

To feed the timber elements to the flighted conveyor, a feeding device comprising a sliding sur- face which extends obliquely upwards from the flighted conveyor has preferably been arranged to the apparatus in accordance with the invention near the latter idler relative to the conveying direction of the timber elements, for sliding the timber elements flat along the sliding surface to the flighted conveyor to the front of the flight which moves around the idler. The sliding surface enables automatic and fast feeding of the timber elements to the flighted conveyor. The sliding surface is preferably at an angle of about 30 degrees relative to the vertical direction. That is a suffi- ciently sharp angle to provide a fast sliding motion, and yet a sufficiently blunt angle to hold the timber elements firmly against the sliding surface by means of gravity. As a flighted conveyor normally comprises two drawing members side by side at a distance from each other, there is accordingly preferably at least one sliding surface near each drawing member of the conveyor.

To automatize the operation, the feeding device preferably also comprises a detector for the po- sition of the flight which moves around the idler, and a holder which is controlled on the base of the position data acquired from the detector for holding in place the timber elements fed to the sliding surface and for releasing them so as to slide to the flighted conveyor at a suitable moment. A suitable moment naturally refers to the moment where the timber element slides between the two flights that have opened relative to each other, wherein the latter flight then starts to push it forward.

LIST OF FIGURES

In the following section, the invention will be described in more detail with reference to the accompanying drawings, in which . Fig. Ia and Ib represent one embodiment of the apparatus in accordance with the invention and the operation of the apparatus, and

Fig. 2 shows details of the apparatus in ac- cordance with Fig. Ia and Ib.

DETAILED DESCRIPTION OF THE INVENTION

Fig. Ia shows a side view of the latter end, relative to the conveying direction, of a flighted conveyor 1 mounted so as to have a horizontal conveying direction. The actual moving conveyor is formed by a chain 3 which has been positioned to pass around a chain pulley 2. Flights 5 which extend outwards from the link formed by the chain passing around the chain pulley have been mounted to each outer chain link 4 of the chain for conveying planks 6 between the chain pulleys along the upper portion of the link formed by said chain so that the planks are pressed between successive flights at the faces 7. The flights are mutu- ally identical, each one operating as an actuating element which pushes the plank in front of it and as a counter-member for the next plank which is being pushed by the flight behind it.

Arranged in conjunction with the latter end of the flighted conveyor shown in Fig. Ia is a feeding apparatus 8 comprising, first of all, a sliding support 9 which extends, relative to the conveying direction of the conveyor, back substantially from the chain pulley and obliquely upwards at an angle of about 30 degrees relative to the vertical direction, and has been positioned aside from the level of the chain pulley 2, so that the planks can be slid along the sliding support to the conveyor to a position where the space between the flight 5a which is still moving around the chain pulley and the flight in front of it has partly opened. To time correctly the feeding of the plank to the flighted conveyor, the feeding device 8 comprises a flight detector 10 which has been arranged near the idler and may be for example an optical or a magnetic indicator. Furthermore, in con- junction with the sliding surface is a holder 12 which is controlled on the base of information acquired from the flight detector and operated for example by a pneumatic or hydraulic cylinder 11 for holding in place the plank 6 or other timber element which has been fed to the sliding surface 9, and for releasing it at the suitable moment so as to slide to the conveyor to the front of the flight which is moving around the idler. Once the plank has been released and has slid to the conveyor in accordance with Fig. Ib, the holder is returned to the initial position to receive the next plank which is fed to the sliding surface. In addition of timing the feeding, the holder is used for shortening the free path of the plank slide and thereby decelerating the input speed to the con- veyor, which also brings down failures caused for example by bouncing of the plank. A conveyor provided with the automatic feeding apparatus can be incorporated into an automatic production control system of a timber production line, thus minimizing the need of manual work.

Each flight of the flighted conveyor 1 comprises in accordance with Fig. 2 a body part 13 which has been mounted directly to the outer chain link 4 of the chain 3 so that it extends perpendicularly out- wards from the chain. The flight comprises, relative to the movement direction of the chain, at the front side of the body part a push part 14, and at the back side a stop part 15 which has been supported on the body part by strings 16 so as to move in the longitu- dinal direction of the chain 3. In practice, the spring-suspended stop part changes the thickness of the flight according to the varying thickness of the timber elements and, on the other hand, ensures that a sufficient pressure force is always applied to the faces 7 of the planks to hold the planks firmly in place during conveyance. Instead of a spring, the required flexibility could also be alternatively realized for example by means of flexible rubber members. Also friction members 17 made from rubber and arranged to the push part enhance the holding in place of the plank, particularly during the feeding step as the plank is initially supported only at the back. Alternatively, the friction members could also be realized for example as non-slip metal surfaces.

In the apparatus of Fig. Ia, Ib and 2, the timber elements have been designated to be lowered down to the level of the upper surface of the chain during their feeding to the conveyor. For this purpose, each outer chain link 4 of the chain comprises, at the front side of the body part 13 of the flight, a support edge 18 for supporting the side 19 of a timber element against it. Lowering the timber element down to the level of the chain minimises the path on which the timber element fed to the conveyor is supported only at the back by the flight 5b which is still mov- ing around the idler before being pressed between two successive flights.

The distance between the flights 5 and the flexibility of the stop part 15 has been so dimensioned in the apparatus in accordance with the figures that objects with a thickness of 35 - 50mm can be pressed between two successive flights. The push and the stop parts of the flight extend to a height of about 100mm from the support edge 18. Such dimensioning of the flights enables firm conveyance of timber elements which are up to 250mm wide. The apparatus as presented in Fig. Ia, Ib and 2 has been studied in practice and found to provide extremely remarkable advantages in terms of conveying efficiency and reliability compared to the known solu- tions. The apparatus has been used for conveying up to 55 planks per minute in long-duration test runs without any malfunctions.

It should be noted that the invention is not limited merely to the examples referred to above; in- stead, many variations are possible within the scope of the claims.

Claims

1. An apparatus for conveying elongated timber elements (6) in their crosswise position, comprising a flighted conveyor (1) in which flights (5) are supported on an endless drawing member (3) , such as chain, which has been adapted to pass around two idlers (2) positioned at a distance from each other and supported to rotate substantially in the vertical direction, the flights being supported to extend out- wards from the link formed by the drawing member, for conveying the timber elements (6) along with the movement of the drawing member so that they are pressed between the flights, characterized in that the flighted conveyor (1) comprises successive flights (5), each one comprising a body part (13) and, relative to the moving direction of the drawing member, a push part (14) at the front side and a stop part (15) at the back side, so that one of the push part and the stop part has been arranged to be flexible relative to the body part in the longitudinal direction of the drawing member, for pressing the timber elements (6) at their faces (7) between the push part of the latter of two successive flights and the stop part of the preceding one.

2. The apparatus in accordance with claim 1, characterized in that the flights (5) are mutually similar.

3. The apparatus in accordance with claim 1 or 2, characterized in that the stop part (15) is supported on the body part (13) by a spring (16) so as to move in the longitudinal direction of the drawing member (3) .

4. The apparatus in accordance with any one of claims 1 to 3, characterized in that the distance between successive flights (5) and the flexibility between the push and the stop part (14, 15) have been adapted so that timber elements (6) with the minimum thickness of not more than 35mm and the maximum thickness of at least 50mm can be pressed between the flights.

5. The apparatus in accordance with any one of claims 1 to 4, characterized in that the flight (5) comprises a friction member (17) for increasing the frictional force between the timber element (6) and the flight (5) .

6. The apparatus in accordance with any one of claims 1 to 5, characterized in that the flighted conveyor (1) comprises a support member (18) substantially at the level of the drawing member (3) for supporting the side (19) of a timber element against it.

7. The apparatus in accordance with any one of claims 1 to 6, characterized in that the push part (14) of the flight extends at a distance of at least about 100mm from the support member (18) .

8. The apparatus in accordance with any one of claims 1 to 7, characterized in that arranged to the apparatus near the latter idler (2) relative to the conveying direction of the timber elements (6) in the flighted conveyor (1) is a feeding device (8) comprising a sliding surface (9) which extends obliquely upwards, for sliding the timber elements flat to the flighted conveyor to the front of the flight (5b) which is moving around the idler.

9. The apparatus in accordance with claim 8, characterized in that the sliding surface (9) is at an angle of about 30 degrees relative to the vertical direction.

10. The apparatus in accordance with claim 8 or 9, characterized in that the feeding device (8) comprises a position detector (10) for the flight (5b) which is moving around the idler (2), and a holder (12) which is controlled on the base of the position data acquired from the detector for holding in place the timber elements (6) fed onto the sliding surface and for releasing them so as to slide to the flighted conveyor (1) at a suitable moment.