FEEDING DEVICE The present invention relates to a device for gradual cross-feeding of elongate objects from a loading end to a discharging end, comprising a stationary support frame, which in profile is stepped in at least two sec- tions which are arranged in separate planes and each have at least two upper sliding and supporting surfaces ex- tended in the feeding direction and intended for the objects and which, at their front end in the feeding di- rection, are terminated with a step front edge forming a step down to the sliding and supporting surfaces of a possible subsequent section, and a feeding arrangement, which is also stepped in profile and has one section less than the number of sections in the support frame and the sections of which each have at least two upper sliding and supporting surfaces extended in the feeding direction and intended for the objects and are terminated at their front end in the feeding direction with a step front edge forming a step down to the sliding and supporting sur- faces of a possible subsequent section, the upper sup- porting surfaces of the feeding arrangement in one sec- tion being in a retracted initial position, vertically positioned at a level below the supporting surfaces of the support frame in the corresponding section but at a level above the supporting surfaces of the support frame in a possible subsequent section, and the feeding ar- rangement being reciprocatable along the support frame by means of a power generating means to effect the feeding of the objects by alternating engagement of the objects between the step front edges of the support frame and the feeding arrangement.

Background of the Invention Cross-feeding of elongate objects occurs, inter alia, in the manufacturing industry, e.g. in the wood- manufacturing industry when round timber is to be sup-

plied to a processing line with processors for barking, chipping, sawing and the like. Cross-feeding can, how- ever, also be used for other purposes and in other branches of industry, such as the metal and engineering industry, for cross-feeding of elongate metal blanks.

From e.g. SE 449,476 a device is known of the type mentioned by way of introduction for cross-feeding of round timber piece by piece. To secure piece-by-piece feeding, each section has a length substantially corre- sponding to the diameter of the largest round logs to be fed, and more particularly the length of each section is about 2-3 times greater than the height of the step or the perpendicular distance between the planes of two sec- tions. Further, in the feeding direction the pitch of the device is relatively steep with an angle of about 35° in relation to the horizontal plane for possible excess logs to roll downwards when more than one log is in the same section. The feeding arrangement is supported by and dis- placeable along at least two vertically adjustable girders arranged under the support frame. This makes the feeding device relatively expensive and results in its taking up a relatively great deal of space in the verti- cal direction.

A similar feeding device is disclosed in SE 468,675, but here the feeding arrangement is not displaceable in parallel to the upper supporting surfaces of the support frame but at an angle, which is somewhat smaller in rela- tion to the horizontal plane. Further, the underside of the actual feeding arrangement is provided with a number of bracket-like parts, whose down-facing surfaces form a plane of displacement along which the feeding arrangement is supported and displaceable on rollers or rolls con- nected with the supporting stand. This feeding device is also expensive to manufacture and takes up a great deal of space in the vertical direction.

For cross-feeding elongate objects, preferably round timber, it is also known to use chain conveyors. In this

case, the wood is supported on at least two endless chains, which each run on the upper side of a girder or the like. Such chain conveyors are in particular used for bundle feeding of piles or stacks of wood. Chain con- veyors, however, suffer from a number of disadvantages.

They are expensive as regards purchase as well as opera- tion and maintenance, they take up a relatively large space in the vertical direction and provide no automatic directing of the wood to a perpendicular position in relation to the feeding direction, as do step feeders of the type mentioned by way of introduction. Therefore, chain conveyors are often combined with a steep slope or sliding plane at their discharging end for the directing and correct positioning of the timber when descending.

This requires that the chain conveyor, and thus also the wood, be supported at a relatively high level above the ground or the floor.

Summary of the Invention The present invention aims at obviating the problems and disadvantages of known feeding devices for cross- feeding of elongate objects.

According to a first aspect of the invention, an object is to simplify the construction, reduce the manu- facturing costs and reduce the need of space vertically, transversely of the feeding direction of feeding devices of the type mentioned by way of introduction. At least this object is attained by means of a device according to claim 1.

According to a second aspect of the invention, an object is to provide a device for cross-feeding bundles or stacks of elongate objects, which device is inexpen- sive as regards purchase as well as operation and mainte- nance and which automatically strives to direct the ob- jects to a position perpendicular to the feeding direc- tion. At least this object is achieved by means of a device according to claim 2.

The basis of the invention is thus the knowledge that the design of the step feeder can be substantially simplified and made cheaper and the consumption of mate- rial and space requirements can be reduced if the feeding arrangement is supported displaceably along the same sup- porting surfaces of the support frame as displaceably support the elongate objects or the pieces of wood.

The support frame can be formed in an arbitrary manner, e.g. in the form of a closed deck, flange por- tions directed upwards forming the supporting surfaces.

Preferably, the support frame is, however, formed of girders extended in the feeding direction. In a similar manner, the feeding arrangement can be formed in an arbi- trary manner, but preferably it is formed of girders, which are extended in the feeding direction and arranged at the side of the frame girders. The feeding girders can be supported by the frame girders in many different ways, but in a preferred embodiment each feeding girder section is terminated with a cross girder, which extends between at least two frame girders and is displaceably supported on their upper surfaces.

The support bearing between the feeding arrangement and the bearing frame can be a slide bearing, as in the preferred embodiment. In general, it is then also suit- able to arrange some kind of lubricating device for the slide bearing. This has the advantage of also facili- tating the displacement of the wood on the supporting surfaces. The support bearing could, however, have the form of a roll or the like running on the supporting surface.

The step feeder according to the invention can be designed in the form of a single feeder with relatively short sections and a steep inclination, e.g. an inclina- tion of 30-40° upwards from the loading end to the dis- charging end. In the preferred embodiment of the inven- tion described below, the feeder is, however, designed as a bundle feeder with long sections for accommodating

stacks of wood and substantially no inclination at all between the loading end and the discharging end. When using the feeding device as a bundle feeder, the sup- porting surfaces have preferably an angle of about 15° max, preferably about 100 max and most preferred about 60 max in relation to the horizontal plane. At the dis- charging end, the bundle feeder can be connected to a single feeder according to the invention or some other optional type to feed the pieces of wood one by one to a processor or out onto a conveyor.

When using the invention as a bundle feeder, it is an advantage if each section is as long as possible on the one hand to reduce the costs, and on the other, for the inclination in each section thereby to be small at no level difference or at a small level difference between the loading end and the discharging end. The step length is, however, reduced by the shearing tendency of the wood bundles. If the supporting surfaces are lubricated, the shearing tendency is reduced, thereby also making it pos- sible to increase the section length. In general, the length of section is at least 6 times, preferably at least 8 times and most preferred 10 times greater than the height of the step between adjacent sections.

According to the invention, the feeding device com- prises a support frame including at least two sections, but of course it can comprise an optional number of sec- tions, in which the feeding arrangements can be intercon- nected for synchronized feeding as well as individually controllable for separate feeding.

Brief Description of the Accompanying Drawings In the drawings Fig. 1 is a side view of a feeding devic according to the invention in the form of a bundle feeder with three sections, Fig. 2 is a top view of the feeding device according to Fig. 1,

Fig. 3 is a cross-sectional view of the feeding device according to Figs 1 and 2 and Figs 4-10 are side views showing the feeding device of Figs 1-3 in different operating positions and at different degrees of loading.

Detailed Description of a Preferred Embodiment of the Invention First reference is made to Figs 1-3, which show in detail in a side view, a top view and a cross-sectional view the detailed design of a feeding device according to the invention. It is composed of three sections 1, 1', 1" and includes in total four frame girders 2, which are supported by two stands 3. Each frame girder 2 is com- posed of three straight girder portions, one for each section 1, which are connected in steps so that a step with a step front edge 4 is formed between the sections or the girder portions.

The feeding arrangement includes four feeding girders 5, each composed of two straight girder portions, i.e. one section less than the frame girders, which are interconnected in steps so that a step front edge 6 is formed, directed forwards in the feeding direction, between the sections and at the end of the feeding arrangement. As is shown in Figs 2 and 3, the feeding girders 5 are arranged close to the frame girders 2 and are thereby laterally guided by these. The feeding girders are further placed so that their top faces 7, serving as sliding and supporting surfaces, are located at a level under the top faces 8, serving as sliding and supporting surfaces, of the frame girders 4 in the corre- sponding section (i.e. in a retracted initial position), but at a level above the supporting surfaces 8 of the frame girders in the subsequent section.

At the downstream end of each feeding girder sec- tion, the feeding girders are interconnected by way of a cross girder 9, which extends continually across and is supported by the frame girders 2 in the subsequent sec-

tion. The contact surfaces between the cross girders 9 and the frame girders thus serve as a slide bearing by way of which the feeding arrangement is supported on the frame girders and is reciprocatable along these. Suit- ably, some kind of friction-reducing lining 10 can be arranged between the cross girders and the frame girders, and preferably the step feeder is also provided with some kind of lubricating device (not shown in detail) for additional reduction of the friction. For reciprocating the feeding arrangement along the frame girders, a hydraulic cylinder 11 is arranged between the rear stand and the feeding arrangement.

In the shown embodiment, the feeding girders 5 and the cross girders 9 have a height which is about half the height of the frame girders. As a result, the supporting surfaces 7 of the feeding girders are located at a level substantially half-way between the supporting surfaces 8 of the frame girders in the same section and in a subse- quent section.

The rear end of the first section of the feeding arrangement is also supported on the supporting surfaces 8 of the frame girders by way of a cross girder 12. This end of the feeding arrangement also includes upwardly directed stanchions 13 to facilitate the loading of wood and secure the feeding of the wood from the first sec- tion 1.

To allow feeding of substantially all the wood from one section to the next, the frame girders 2 have re- cesses 14 in their respective step front edges 4. This makes it possible for the cross girders 9 to be fully re- tracted under the frame girders 2 in the retracted ini- tial position, as shown in Figs 1 and 2.

The feeding device according to the invention can, in a practical embodiment for bundle feeding, have a width of about 3.5 m and a length of each section of about 2.0 m. The supporting surfaces 7 and 8, respectively, of the feeding girders and the frame

girders then make an angle of about 5° with the horizontal plane if the feeding device is arranged for substantially horizontal feeding from the loading end to the discharging end. The height of the step at the step front edges 4 and 6, respectively, is determined by the diameter of the biggest pieces of wood, which are to be fed by the step feeder, and the height of the step can suitably amount to about half of this diameter.

In the following, reference is made to Figs 4-10, which show the function of the feeding device when the wood is loaded and fed from the loading end to the dis- charging end.

Fig. 4 shows the feeding device with the feeding arrangement in a retracted initial position and a bundle of wood 15 loaded in the first section. The wood is here supported by the supporting surfaces 8 of the frame girders 2 of the first section.

In Fig. 5, the feeding arrangement is advanced by extending the hydraulic cylinder 11, and the bundle of wood is moved along the frame girder 2 of the first sec- tion and is successively moved down onto the feeding girders 5 in the first section of the feeding arrangement to finally be fully supported, as is shown in Fig. 5, on the supporting surfaces 7 of the feeding girders 5.

Subsequently, the feeding arrangement is moved back- wards again by shortening the hydraulic cylinder 11. By engaging the step front edge 4 between the first and the second sections of the frame girders, the bundle of wood is successively conveyed from the feeding girders in the first section of the feeding arrangement down onto the frame girders in the second section to finally lie en- tirely on the supporting surfaces 8 thereof, as is shown in Fig. 6.

In Fig. 7, an additional bundle of wood has been loaded on the frame girders in the first section.

In Fig. 8, the feeding arrangement is again advanced by extending the hydraulic cylinder 11 and in addition to

the bundle of wood on the first section of the frame girders being conveyed down onto the feeding girders in the first section of the feeding arrangement, the bundle of wood on the second section of the frame girders is conveyed down onto the feeding girders 5 in the second section of the feeding arrangement by engagement of the step front edge 6 with the wood.

In Fig. 9, the feeding arrangement is again moved to the initial position and the bundles of wood are moved away from the feeding girders down onto the second and the third sections of the frame girders by engaging the step front edges 4 between the first and the second and the second and the third sections, respectively, of the frame girders.

In Fig. 10, another bundle of wood has been loaded on the frame girders in the first section and the feeding device is in its initial position for a new feeding step.

At the discharging end of the feeding device, some kind of processor or an additional feeding device, e.g. a single feeder, can suitably be arranged for further handling of the wood.