Background Art As a rule, equipment for wrapping insulating mate- rial is connected directly to a production line where the material is sawn and/or cut in specified sizes. This is a continuous process where the boards are usually supplied at a rate of one board per second or faster.

When wrapping pads or boards of a soft material, such as insulating material, a method has since long been applied, in which rectangular boards are stacked into a stack, compressed in the direction of stacking into a package, and then provided with a coating of a thin flex- ible material, such as plastic, which maintains the pack- age in its compressed state.

According to a frequently used method, the packages are inserted in their longitudinal direction with the aid of some type of pushing means into an opening of a sack or tube of plastic, which is then possibly welded toge- ther at its open end.

According to the above method, the sides of the package are subjected, perpendicular to the direction of compression, to a mechanical pressure, which results in an unfavourable pressure gradient. There is a risk that the fibres of the material, if any, will be damaged if excessive mechanical pressure is applied to the pack- age. This is a major problem since most insulating mate-

rials consist of fibre materials which are sensitive to pressure being applied transversely of the fibres.

Furthermore, the compressed package, while being fed, frequently passes irregularities in the conveying paths, such as bumps or gaps. These irregularities are propagated through a plurality of boards in the compress- ed package and result in additional pressure gradients and damage the fibres.

Summary of the Invention The object of the present invention is to provide automatic stacking and compressing, which in every respect are satisfactory, of an insulating material with- out the material being subjected to detrimental pressure gradients.

According to the invention, this object is achieved by a device which is of the type stated by way of intro- duction and which comprises receiving means comprising first drive means which are arranged on two opposite sides of the stacking shaft and to each of which at least two receiving surfaces extending along the width of the shaft are arranged, which in pairs are arranged in level with each other and are movable by said first drive means in the vertical direction of said shaft, and compressing means comprising second drive means which are arranged on two opposite sides of the stacking shaft and which are individually movable in relation to said first drive means, to each of which at least two compressing surfaces extending along the width of the shaft are arranged, so that the receiving surfaces in pairs are arranged in level with each other and are movable by said second drive means in the vertical direction of said shaft, each pair of receiving surfaces being adapted to successively receive elements, one by one, and to support the same to form a stack, and each pair of compressing surfaces being adapted to be individually movable from above in the direction of the stack, for compressing the same.

This construction renders stacking and compressing in a continuous process possible, in which the soft ele- ments are not subjected to considerable power gradients.

The pair of receiving surfaces which supports the stack can be adapted to be gradually movable downwards as the stack grows in the vertical direction. As a result, the entire height of the shaft is utilised.

The first and second drive means may consist of elongate, flexible elements, preferably chains, which run in individually moving paths between deflecting means adjacent to the upper and lower part of the shaft, and which support said receiving surfaces and compressing surfaces, respectively, thereby forming a double pater- noster-like arrangement. Preferably said first and second flexible elements run individually along an essentially common path, and said compressing surfaces and receiving surfaces are arranged alternatingly along said path. The receiving means and the compressing means each comprise preferably two pairs of receiving surfaces and two pairs of compressing surfaces.

This construction results in the receiving means being operable individually in relation to the compress- ing means, so that a stack can be compressed by the com- pressing means while at the same time a new stack can be received by the receiving means.

The device further comprises at least one first con- veying means which is movable between a first deactivat- ed position in which it is located outside the stacking shaft, and a second activated position in which it is located parallel with the compressing surfaces and con- tacts the upper side of the stack so as to allow, without frictional forces acting against the motion, conveyance of the stack transversely of the compressing direction.

With this discharge from the stacking area, the motion occurs without frictional forces acting on the package, which result in conventional discharge in simi- lar situations, where, while discharging, compressing

means are in contact with the material in the package and thus cause friction. Moreover, no pressing force need be applied to the package, which also normally occurs in the form of a hydraulic discharging means or the like. The compressing process according to this embodiment thus affords handling which is very gentle to the material.

Preferably, the movable conveying means consists of one or more belt conveyors which, in cooperation with a belt conveyor located under the stack, can discharge the stack. Although it is convenient for all belt conveyors to be driven, this is not necessary. Thus, for example one or more of the belt conveyors moved towards the pack- age may have no drive and can only afford elimination of frictional forces.

According to a further embodiment of the invention, the step of compressing the stack comprises conveying of the stack between belt conveyors which are located on two opposite sides of the stack and which converge. Compress- ing the stack in this fashion results in a gradual com- pression which is gentle to the material, especially to fibrous materials.

Brief Description of the Drawinqs The present invention will now be described in more detail with reference to the accompanying drawings, which for the purpose of exemplification illustrate preferred embodiments of the invention.

Fig. 1 is a schematic side view of a device accord- ing to the invention adapted to carry out the method according to the invention.

Fig. 2 is a schematic sectional side view of a com- pressing assembly according to the invention.

Fig. 3 is a schematic front view of the compressing assembly in Fig. 2 in a first position.

Fig. 4 is a schematic front view of the compressing assembly in Fig. 2 in a second position.

Description of a Preferred Embodiment Wrapping of material takes place according to an embodiment of the invention along a process chain accord- ing to Fig 1. The material, which in the example shown consists of boards 1 of a fibrous insulating material, is fed on a conveyor belt 2 to a compressing assembly 3 according to the invention where the boards are stacked and compressed. The compressed package 4 is then intro- duced by a feeding assembly 5 into a thin and flexible wrapping material 6 and further to a sealing arrangement 7, where the packages are sealed, first along the feeding direction and then transversely of the feeding direction.

The entire device is held together by a stand 8, prefer- ably consisting of a plurality of welded-together beams.

Figs 2-4 schematically illustrate an embodiment of the compressing assembly 3 according to the invention.

With reference to Fig. 2, numeral 2 designates a conveying path, preferably a conveyor belt, which feeds elements 1 of an insulating material to the compressing assembly. The elements can be in the form of boards and will below be referred to as boards, but could just as well have a different, essentially extended, form.

The compressing assembly has in its upper portion a loading means 12 which comprises two rotatable surfaces or blades 13. The blades 13 are movable between a hori- zontal position (Fig. 4), in which they support between them a board 1, and a vertical position (Fig. 3) in which they do not offer any support to the board. The loading means 12 thus operates in two strokes, the first, with the blades in the horizontal position, receiving a board 1 from the conveying path 2, and then, by turning the blades to a vertical position, letting the board 1 fall down.

Below the loading means 12 there is a stacking shaft 14 which is adapted to stack and compress boards 1. In the shown example, the shaft comprises two individually

movable shelf assemblies 17,19a, 19b, 20a, 20b, 18,21a, 21b, 22a, 22b.

Each shelf assembly comprises drive means, such as gear-driven chains 17,18, which run in endless paths between deflecting means 15,16, such as gear wheels, in the upper and lower end of the shaft 14. A plurality of shelves 19-22 are arranged adjacent to the chains and extend essentially perpendicular to the extent of the chains 17,18, and preferably transversely of two oppo- site sides of the shaft, along their entire width b.

The shelf assemblies thus work in a paternoster-like fashion, with shelves that are movable up and down along a chain-driven path. The paths are individually movable but have a mutually dependent pattern of motion, which will be described in more detail below.

The first shelf assembly 17,19a, 19b, 20a, 20b is a receiving means and has in the shown example two pairs of receiving surfaces 19a-b, 20a-b, each comprising a shelf along each side of the shaft, symmetrically arranged on the same level. The two pairs of shelves 19a-b, 20a-b are advantageously arranged diametrically opposite to each other so that when a pair of shelves 19a-b is located at the very bottom of the shaft, the other pair of shelves 20a-b is located at the very top.

The second shelf assembly 18,21a, 21b, 22a, 22b is a compressing means and has in the shown example two pairs of compressing surfaces 21a-b, 22a-b, each compris- ing a shelf along each side of the shaft, arranged on the same level. The two pairs of shelves 21a-b, 22a-b are advantageously arranged diametrically opposite to each other so that when one pair of shelves 21a-b is located at the very bottom of the shaft, the other pair of shelves 22a-b is located at the very top. In Figs 2 and 4, however, the shelves 21a-b, 22a-b are positioned approximately on the same level, one pair of shelves 21a-b being on its way down, and the other pair of shelves 22a-b being on its way up.

Below the shaft 14 there is a conveying path, such as a belt conveyor 23, which has its direction of motion A parallel with the longitudinal direction of the shelves.

Somewhere in the middle of the shaft 14 there is a conveying means 24a-c which is adapted to move at least one belt conveyor 24a-c from a position outside the shaft to a position parallel with the belt conveyor 23. In the example shown, the conveying means consists of four belt conveyors (of which only two are to be seen in Fig. 2 and Figs 3-4, respectively), which are arranged in pairs on the two open sides of the shaft. Each belt conveyor 24a-c is with the aid of a power means, such as a hydraulic piston 25a, 25c, movable from a vertical position (indi- cated by full lines in Fig. 2) to a horizontal position (indicated by dashed lines in Fig. 2).

When the loading means 12 lets a board 1 fall down from its blades 13, this board is received by one pair of shelves 19a-b of the receiving means. For each board that is received, the pair of shelves 19a-b is moved step-by- step downwards by the chains, and a new stack 26 forms gradually (see Fig. 3).

When the stack 26 consists of the desired number of boards, the pair of shelves 19a-b is moved to its bottom position, the stack 26 being transferred to the belt con- veyor 23 and the pair of shelves 19a-b will be without load. The receiving means is now moved to a position in which the other pair of shelves 20a-b is prepared to receive a board 1 from the loading means 12, thereby forming a new stack 26' (see Fig. 4).

When a stack 26 has been placed on the conveying path 23, one pair of shelves 21a-b of the compressing means is moved downwards and thereby compresses the stack 26 to the desired height. Thanks to the fact that each shelf assembly has two pairs of shelves, the loading of boards can take place essentially continuously by a new

stack 26'being begun while the first stack 26 is being compressed.

The belt conveyors 24a-c are then pivoted with the aid of the power means 25a, 25c to their second horizon- tal position, in which they are positioned parallel with and in contact with the upper side of the stack (indicat- ed by dashed lines in Fig. 2). The belt conveyors 24a-c thus relieve the pair of shelves 21a-b of the compressing means from the compression pressure.

The compressed stack 6 is now positioned between the belt conveyors 24a-c and the belt conveyor 23 and can be removed from the shaft by being driven by one of, or pre- ferably all, the belt conveyors 23,24a-c.

Controlling of the drive means 17,18 in the correct manner so that the desired number of boards are stacked and the desired compression is obtained, and coordination of all motions are provided by sensors in suitable posi- tions in the shaft, which transmit signals to control electronics. For example, there are sensors 27 for indi- cating when a board 1 has been placed on top of the stack 26, said sensor also counting the number of boards 1 in the stack 26, and sensors 28 indicating when the com- pressing surfaces have reached a position corresponding to the desired degree of compression, etc.

An important property of the inventive device thus is that the drive means 17,18 are individually movable relative to each other. At the same time their patterns of motion are, of course, most dependent on each other, the position of the receiving means affecting the opera- tion of the compressing means and vice versa.

Reference once more being made to Fig. 1, the com- pressed package 4 can now be conveyed by the feeding assembly 5 in a direction B. The process chain shown in Fig. 1 is only illustrated for the purpose of exemplifi- cation, and it will be appreciated that the present invention can be applied in all processes in which stack- ing and compressing of soft elements are performed.

It will be appreciated that the invention accord- ing to the appended claims is not restricted by the above description of preferred embodiments. The described devices can, for example, vary in respect of form as well as material, the person skilled in the art being expected to make the adaptations required by a specific situation.