TECHNICAL FIELD

The present invention relates to an arrangement for the pro¬ duction of an elongated bar-like structure with the aid of a material compression unit which functions to compress a mixture of plastic material and filler material and to press the compressed material through a nozzle means and into a matrix which includes walls or wall-sections that can be moved in the feed direction of the bar-like structure, wherein the movement pattern of respective matrix walls is so adapted and so coordi¬ nated with the movement pattern of other matrix walls or wall- sections as to enable the bar to be advanced through the matrix in a direction away from the compression unit.

BACKGROUND PRIOR ART

Various arrangements of this kind are known to the art.

The most relevant prior art is illustrated and described in the International Patent Application PCT/SE90/00748, having the International Publication Number WO 91/07270.

This prior art publication teaches a particular movement pattern of the matrix walls which enables the bar under manufacture to be advanced through the matrix in a direction away from a material compressing arrangement or unit. This is achieved by synchronous movement of three wall sections at time intervals when a fourth wall section rapidly returns to its original position.

It is stated on page 15, fir ^* v paragraph, of the publicatio that each wall section coacts 'ith a hydraulic piston-cylinde device (not shown) which functions to move respective wal sections backwards and forwards in the longitudinal directio of the bar. Certain wall sections are moved synchronously wit

SUBSTITUTESHEET

one ^" another at each time interval, while another wall section moves asynchronously in the opposite direction.

It is known from Swedish Patent Specification 415, 547 (Patent Application 7809709-4) to move matrix wall sections backwards and forwards.

The matrix taught by this publication is also comprised of wall sections and at least one of said wall sections is caused to move in relation to the bar-like structure under manufacture.

The basic concept of the invention defined in this publication resides in introducing into a compression chamber part of the total amount of fibrous material required to produce a bar of determined length, and there compressing the material through the medium of a compression means. The compression means is then moved in the compression chamber away from its material compressing position, so as to enable a further part of said total amount of fibrous material to be introduced into the compression chamber and there compressed by the compression means, this further part being compressed between the earlier compressed part and a compression device which forms part of the compression means.

As a result of this process, the bar is built up successively in the compression chamber from individually produced bar-parts so as to enable the bar to be produced in selected lengths, by causing the compression means, after compression, to move not only the most recently compressed bar-part through the matrix but also those parts of the bar that have earlier been com¬ pressed.

It is particularly shown in the aforesaid patent specification with reference to Figure 6, that the matrix 4 is comprised of a number of beams 22' which extend parallel to the wall sections 19, 20, 21 and 22. A hydraulic piston-cylinder device 23 having a piston and a piston rod 24 functions to rotate an

arm '25 and therewith move the wall section ,; forwards and backwards. The arm 25 is connected rotatably t.. the beam 22' by means of a shaft or axle 26 and the free end 25a is disposed between two supports 26a, 26b connected to the wall section 22. Reciprocatory movement of the piston rod 24 results in recipro- catory movement of the wall section 22 in the arrowed direc¬ tions.

This arrangement ensures that the matrix wall sections 22 will move relative to the bar 15 and that the coefficient of friction between the inner surface of the wall section 22 -and the outer surface of the bar 15 is reduced.

It is also indicated that each wall section 19, 20, 21 and 22 shall be provided with a device identical to the device illustrated in Figure 6 for the wall section 22.

International Patent Application PCT/SE90/00501, having Publication Number WO 91/01864, also teaches the use of a matrix comprised of movably arranged wall sections.

SUMMARY OF THE INVENTION

TECHNICAL PROBLEMS With regard to the standpoint of techniques described above it has been established in practice when using hydraulically operated piston-cylinder devices to move the matrix walls forwards and backwards in the manner proposed in the aforesaid International Patent Publication WO 91/07270 that the speed at which the bar-like structure can be advanced through the matrix is limited primarily by the difficulties encountered in quickly returning a wall section in a direction opposite to the direction of movement of the other three wall sections and within a short space of time.

A technical problem therefore resides in providing conditions which will enable movement of the matrix walls in both direc¬ tions to be related to an oscillating (flywheel) mass which.

through the medium of activated mass forces and oscillatory energy, offers rapid and mainly non-elastic movement in contrast to the elasticity that is inherent in any hydraulic system.

It will be seen that a further technical problem is one of realizing the significance of moving the matrix wall in mechanical co-action with a cam disc which, when rotated, will drive the matrix wall forwards and backwards.

Another technical problem resides in the necessity of positi¬ vely controlling each matrix wall in one direction by a first cam disc and in a second, opposite direction by a second cam disc.

Another technical problem resides in realizing the simplifi¬ cations in construction that can be achieved when each and every cam disc for moving each and every matrix wall is driven synchronously by a mutual driving force or means, preferably by an electric motor.

It will also be seen that a further technical problem resides in realizing that a simple construction can be obtained when the cam discs for a first wall section are driven by means of a first drive shaft and the cam discs for a second and a third wall section are driven by an angled gear or bevel gear arrangement, and the cam discs for a fourth wall section are driven by means of a chain drive means.

Another technical problem resides in realizing the advantages and structural simplifications that are related to the feature of allowing the first shaft to move three matrix walls that are positioned adjacent to one another.

A further technical problem resides in realizing the signifi¬ cance of providing the first cam disc with a peripheral cam profile or curve which has a gradually increasing radius and

which covers approximately 270° of one revolution, so that the related matrix wall and the elongated bar-like structure can be moved slowly with the aid of this first cam disc.

It will also be seen that a technical problem resides in realizing the significance of providing the second cam disc with a peripheral cam profile or curve which has a pronouncedly increasing radius and which extends through slightly less than 90° of one revolution, so as to be able to return the matrix wall quickly to an original position and to move relative to the elongated bar-like structure and the remaining matrix walls.

A further technical problem is found in realizing the advantag- es that are afforded when the radius enlargement is adapted directly to the longitudinal movement of the matrix wall, thereby enabling the length of said movement to be readily adjusted by changing the cam profile of a cam disc.

A further technical problem also resides in realizing the significance of placing the rotational centres of rollers or ball bearings coacting with respective cam discs in a straight line and to space this line slightly from the common centre of rotation of the two cam discs.

SOLUTION

The object of the present invention is to solve one or more of the aforesaid technical problems, taking as its starting point an arrangement for producing an elongated bar-like structure which comprises a material compression unit which functions to compress a mixture of plastic material and filler material and to press the compressed material through a nozzle and into a matrix in the direction of movement of the bar-like structure and the movably mounted matrix walls, wherein the movement pattern of each individual matrix wall is so adapted as to enable the bar-like structure to be advanced through the matrix in a direction away from the material compression unit.

According to the present invention, each of said matrix walls coacts mechanically with a cam disc which, when rotated, moves the matrix wall backwards or forwards.

In accordance with preferred embodiments lying within the scope of the inventive concept, each and every matrix wall is arranged to be moved in one direction by a first cam disc and in another direction by a second cam disc.

It is also proposed that each and every cam disc for each and every matrix wall is operated synchronously by means of a common drive means or common drive force, such as an electric motor.

It is also proposed that a first shaft drives or operates two cam discs for a first wall section, and that two cam discs drive or operate a second and a third wall section through the medium of an angle-gear arrangement, and that two cam discs for a fourth wall section are driven by a second shaft through the medium of a chain drive means.

The matrix walls driven by the first shaft will preferably be positioned adjacent to one another.

It is also proposed that the first cam disc will have a cam profile or camming curve whose radius increases gradually and which embraces approximately 270° of the circumference,* and that the second cam disc is given a cam profile or camming curve that has a pronouncedly increasing radius and embraces slightly less than 90° of ^* the circumference.

It is applicable to the configurations of both cam discs that the increase in radius is adapted to the longitudinal movement of the matrix wall, and ^' the increase in radius should therefore be the same for both cam discs.

It is also proposed that the centres of rotation of rollers or ball bearings coacting with respective cam discs are placed in a straight line and at a small distance from the rotational centres of the two cam discs.

ADVANTAGES

The primary advantages afforded by an inventive arrangement reside in the creation of conditions whereby reciprocating movement of the matrix walls is controlled forcefully and positively in conformity with the longitudinal extension of the elongated bar-like structure, thereby enabling the matrix walls to be moved rapidly at a speed greater than that which can be achieved with hydraulically operated devices.

The primary characteristic features of an inventive arrangement are set forth in the characterizing clause of the following Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of an arrangement at present preferred and including the significant characteristic features of the present invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 is a greatly simplified illustration in side view of an arrangement for producing an elongated bar of known construction;

Figure 2 is a cross-sectional view of a matrix wall feeding unit in accordance with the invention; and Figures 3-6 illustrate forward and backward movement of respective matrix walls with the aid of the cam discs.

DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED

Figure 1 illustrates a known machine 1 for mixing plastic material with filler and/or reinforcing material.

The machine 1 is preferably capable of heating .the plastic material to a temperature which lies only just below the temperature at which the plastic material becomes liquid, but at a temperature at which the plastic becomes tacky.

In the illustrated case, shredded or cut paper is used as the filler material and a plastic material which is liquidized or almost liquidized by heating. The proportion of plastic material used should be less than 50%, but preferably about 10%. A typical proportion will lie between 20 and 50%, say about 40%.

Plastic material, such as polyethylene, may be present in a proportion of 25-40% when paper is used as filling material.

The machine 1 includes a precompressing device in the form of a screw feeder, such that a mixture of plastic material and filler is delivered under pressure through a tube 2 to a space 3. The space 3 can be said to be defined by an internal, rotatable core and an external sleeve 5.

The material is compressed gradually in the space 3 and exhibits essentially the pressure imparted thereto as it passes through the tube 2. The material is compressed to a much greater extent in a region 3' downstream of the space 3. The plastic material has here a liquid or tacky state.

As the material passes through the machine to the left in Figure 1, the temperature of the material increases so as to soften the plastic material and so that the plastic material and the filling material will be thoroughly mixed together in the region 3', with all of the plastic material present essentially in a liquid state. The material is finally comp¬ ressed in a nozzle in the machine 1, and is fed continuously

from' the end of the first region 3' and through a nozzle 4 where it is present in briquette form as a bar-part "A".

The briquette-like bar-part "A" is advanced continuously through the nozzle 4 and into a matrix 10, which is comprised of four movable wall parts 11, 12, 13 and 14.

T- nozzle 4 is shown to be spaced slightly from the end part 1 ^• _,. ^• _. of the matrix 10, for instance at a distance of about 0.2 m, although there is nothing to prevent this distance from being smaller than shown.

It is pointed out in this connection that the bar section "A" is mechanically weak and that it is therefore necessary to further work and cool the bar section and to finally compress the section to some extent in the matrix 10.

The primary purpose of the present invention is to provide a mechanical arrangement for displacing the four matrix walls 11, 12, 13 and 14 in a manner described in more detail with reference to Figure 3 in the International Patent Publication WO 91/07270, said matrix walls being disposed to define a rec¬ tangular cross-section.

The matrix walls have been identified by the same reference signs or numerals in Figure 2, which is a sectional view of a matrix-wall feeding unit 20 constructed in accordance with the invention.

The compressed material "A" located between the matrix walls is intended to be fed towards the viewer of Figure 2 with the aid of the feeding unit 20.

The unit 20 includes a ^" motor 21 (not shown) which coacts with a shaft 22 through the medium of a chain-and-sprocket drive 21a.

A shaft 26 is operated and rotated through the medium of another chain drive 21b.

The shaft 22 is intended to drive a shaft 23 through the medium of an angle gear arrangement or bevel gear arrangement 22a, and a shaft 24 through the medium of an angle gear arrangement or a bevel gear arrangement 22b.

A shaft 22 coacts with two cam discs 11a, lib which cause the matrix wall 11 to move backwards and forwards, depending on their direction of rotation.

Similarly, the shaft 23 carries two cam discs 12a and 12b, the shaft 24 carries two cam discs 13a and 13b and the shaft 26 carries two cam discs 14a and 14b.

The cam discs 11a, lib; 12a, 12b; 13a, 13b and 14a, 14b are so positioned in relation to one another as to enable the matrix walls 11, 12, 13 and 14 to move in the movement pattern illustrated in Figure 3 of the aforesaid patent publication, and consequently a more detailed description of the function of the cam discs 11a and lib will suffice to obtain an under¬ standing of the present invention. This will be described in more detail with reference to Figures 3-6, in which the cam discs 11a and lib are shown in different positions of rotation.

For clarification purposes, the cam disc lib has been shown in broken lines in Figures 3-6 and the cam discs 11a in full lines.

A roller or ball bearing 30 (hidden in Figure 2) is rotatably mounted on a shaft 31 which is firmly connected to the matrix wall 11 through a supporting part 40 which coacts with a plate 41 positioned slightly beneath the rotational centre 22' of the shaft 22. The roller 30 is activated by a cam profile or camming curve 11a'.

A wheel or a ball bearing 30' is similarly connected firmly to the matrix wall 11 and is mounted for rotation about a rota¬ tional axis 31'. This axis is located significantly above the rotational centre 22' and a straight line 45 extending between the centres of rotation 31, 31' of the rollers 30, 30' coacting with respective cam discs 11a, lib is spaced slightly from the centres of rotation 22' of the two cam discs (see Figure 6).

The angle of inclination in this case will preferably lie between 10 and 20°, preferably about 15°.

In the Figure 3 illustration, the roller 30 has left the camming curve 11a' and the roller 30' has been brought into engagement with the initial- part of the camming curve lib' , causing the matrix wall 11 to lie close to the nozzle 4.

Upon rotation in the direction of the arrow R through an angle of 90° (as shown in Figure 4), the roller 30' will run along the camming curve lib' and therewith move the wall part 11 through a distance "a" in relation to the position shown in Figure 3.

Further rotation of the cam discs causes the matrix wall 11 to move a further distance "b" in relation to Figure 3, wherein the speed of this movement conforms with the speed at which the bar-like structure "A" is advanced.

Figure 6 shows that the roller 30' has been moved maximally to the left by the camming curve lib' , this maximum distance corresponding to the total distance "c", through which the bar is advanced.

The rollers 30, 30' and the matrix wall 11 will gradually return to the position ^' shown in Figure 3, as the roller 30 is caused to coact with the initial camming curve 11a' .

As will be seen from the illustrated embodiment, each of the matrix walls is in mechanical coaction with two cam discs by means of which the matrix walls are moved reciprocatingly as the discs rotate.

Each matrix wall is guided for movement in one direction by a first cam disc 11a and in another direction by a second cam disc lib.

All cam discs for all matrix walls are driven synchronously by a common drive source.

A first shaft 22 in the unit 20 functions to drive the two cam discs for a first wall-section 11 and the cam discs for a second wall-section 12 and a third wall-section 13 through the medium of angle gears or bevel gears, and to drive the cam discs for a fourth wall-section 14 by a second shaft 26 through the medium of a chain drive.

The first shaft 22 is arranged to drive matrix walls that are positioned adjacent one another, i.e. the matrix walls 11, 12 and 13.

One of the cam discs lib has a cam profile or camming curve which includes a gradually increasing radius and which embraces about 270° of the cam disc circumference.

The adjacent cam disc 11a has a cam profile or camming curve which has a pronouncedly increasing radius and which embraces slightly less than 90° of the full circumference of the cam disc.

The increase in radius is adapted to the longitudinal movement of the matrix wall 11 and shall thus be the same for both cam discs.

It will be understood that the invention is not restricted to the aforedescribed and illustrated exemplifying embodiment thereof and that modifications can be made within the scope of the inventive concept as defined in the following- claims.