ARTICLES

Background of the Invention The present invention relates to a device for remov¬ ing wrapping strings or bands from wrapped articles, such as bales of pulp, comprising an intercepting means which is adapted to intercept and take hold of a separate wrap¬ ping string after it has been cut off. In paper mills, for instance, large amounts of bales of pulp are defibrated. As a rule, the bales are wrapped in paper and kept together by wrapping strings or bands. Before the bales are dissolved, the wrapping strings have to be removed. SE 465,459, for example, discloses a device for cutting off wrapping strings.

The cutting device described in SE 465,459 comprises a foot member and a toothed wheel which are arranged on a movable arm and adapted to be applied against a boundary surface of the article passing by the cutting device on a conveyor. The toothed wheel serves to grip the separate wrapping string and lift it onto the upper side of the foot member so as to remove the string somewhat from the article and enable it to be cut off. Cutting may be per¬ formed e.g. between a shearing means and an abutment. One drawback of this cutting device is that the foot member and the toothed wheel have to be applied, and trail and rotate, respectively, against the outside of the pass¬ ing article. As a rule, this does not involve any incon- veniencies when the outside of the article is smooth. How- ever, some articles, e.g. bales of pulp, are usually wrapped in paper which is often torn or folded. As a result, the paper often catches on the foot member, caus¬ ing a stoppage. Further, the bale itself may be damaged, with parts of the paper sheets projecting beyond the normal boundary surface of the bale, thereby making it impossible for the toothed wheel and the foot member to intercept the string. Should the cutting operation fail

for some reason or other, e.g. because the wrapping paper has got stuck, the bale may catch in the foot member, thereby damaging the equipment. Summary of the Invention The present invention aims at eliminating the need of someone removing the wrapping strings from wrapped articles by hand, and thus provides a device for automa¬ tically removing and collecting the strings while the articles are continuously moved in the longitudinal direc- tion. According to the invention, this and other aims are achieved by a device which is characterised more speci¬ fically in that the intercepting means comprises a hook means which has a hooking edge and which is adapted, while the article is moved in the longitudinal direction in relation to the intercepting means, to be applied against, or be located in the immediate vicinity of, the outside of the article with the hooking edge facing against the direction of movement of the article; and a gripping means which has a gripping edge directed in the direction of movement of the article and which is movable between an open position, in which the gripping edge is removed from the hooking edge which is thus free to hook onto a wrap¬ ping string passing by, and a closed position, in which the gripping edge is approached to the hooking edge and the wrapping strings already hooked are squeezed between the hooking edge and the gripping edge. A preferred embodiment of the invention further aims at cutting up the wrapping paper.

The invention also aims at obviating the above draw- backs inherent in prior-art string-cutting devices and providing a device which involves no risks of functional trouble caused by damage to the wrapping paper or to the article itself. Another aim of the invention is that failure to cut off a wrapping string should not result in the article being caught on the cutting device. A further aim of the invention is to enable the string to be cut off even if the surface of the article has been damaged.

These and other aims are achieved by a device for cutting off wrapping strings, which is characterised more specifically in that it comprises a cutting-edge holder which, from a first inoperative position located outside the boundary surfaces of the wrapped article, can be extended or projected along a path of movement towards the article to a second position in which the cutting edge is located at least in the same plane as one of the boundary surfaces of the article; and a sensor for sensing, during relative movement in the longitudinal direction between the device and the article, the position of a separate wrapping string and causing the cutting-edge holder to project towards the article in order to cut off the wrap¬ ping string when this crosses the path of movement of the cutting-edge holder.

Brief Description of the Drawings

In the drawings, Fig. 1 is a side view of a device for removing wrapping strings from bales of pulp; Fig. 2 is a top view of the device in Fig. 1;

Fig. 3 is an end view from the left of the device in

Fig. 1; Fig. 4 is a side view of a cutting device according to the invention; Fig. 5 is a top view of the cutting device in Fig. 4; Fig. 6 is an end view of the cutting device as seen in the direction of conveyance; Fig. 7 is a side view of the intercepting means according to the invention in closed position; and Fig. 8 is a detail view of the intercepting means in Fig. 7 in open position. Description of a Preferred Embodiment

A station which is arranged at a conveying path for bales of pulp and in which wrapping strings are automati- cally removed from the bales will first be described with reference to Figs 1-3. A separate bale 1 is transported on a conveyor 2 in the direction indicated by the arrow 3.

The bales do not always have the same number of wrapping strings 4, but usually have two strings extending in two orthogonal directions. An inventive cutting device, gen¬ erally designated 5, is located between two endless driving elements or chains 6 of the conveyor 2, more precisely substantially beneath a plane of conveyance defined by the conveyor 2. An intercepting means 7 is supported on a level above the bales by an upright frame 8, a pivotable bracket arm 9 projecting from the upper end thereof, and parallel-displacement rods 10 directed down¬ wards from the bracket arm. By means of a pneumatic cylin¬ der 11, the intercepting means 7 can be raised to an upper inoperative position, as illustrated by dashed lines in Fig. 1. The cutting device 5 is arranged just before the intercepting means 7, so that the strings cut off are immediately intercepted and retained by the intercepting means 7.

In this description, the terms "before" and "in front of" are used to indicate a position in a direction against the normal direction of conveyance of the bales of pulp. Correspondingly, the terms "after" and "behind" are used to indicate a position in the direction of conveyance of the bales of pulp. When the bales have strings extending in two ortho¬ gonal directions, the separate bale 1 should first be conveyed through the station oriented in one direction, the strings 4 extending transversally of the direction of travel of the conveyor being cut off by the cutting device 5 and immediately intercepted and retained by the inter¬ cepting means 7. At a turning device, generally designated 12, the bale stops, is lifted and rotated through a quarter of a turn by the cylinder 13, and is lowered onto the con¬ veyor. The bale is then backed to the area in front of the cutting device 5 and again conveyed through the station, the other pair of wrapping strings being cut off, and removed by the intercepting means 7. All the strings have

now been removed, and the bale can thus be conveyed to the next processing station.

At this point, the intercepting means 7 is holding four wrapping strings and is raised to its upper position. By the pneumatic cylinder 14, the bracket arm 9 and the intercepting means 7 are swung aside, as illustrated by dashed lines in Fig. 2, and the strings are then con¬ veniently dropped into a container, for instance a wire coiling reel. To minimise idle time, the intercepting means may instead be swung out and drop the strings after only two strings have been removed from the bale and while the bale is being conveyed to the turning device 12, turned and then backed to the area in front of the cutting device. When the bale returns to the area in front of the cutting device 5, the intercepting means 7 is then again in posi¬ tion to intercept and remove the two remaining strings on the bale. Another bale may then immediately be passed through the station and its first two strings be removed. Figs 4-6 illustrate the construction of the inventive cutting device 5 in more detail. The cutting device include a cutting blade 15 which, by a pneumatic cylinder 16, can be displaced between a lower inoperative position, indicat¬ ed by full lines in Fig. 4, and an upper cutting position, indicated by dashed lines in Fig. 4. A line 17 indicates th level of the upper plane of the conveyor 2, i.e. the plane in which the bales are moved along the conveyor. As appears from Fig. 4, the cutting edge 18 of the blade 15 is, in the first inoperative position, located at a distance beneath the plane of conveyance of the bales and, in the second projecting position, located at a distance above this plane Further, the path of movement of the cutting blade is linea and substantially perpendicular to the plane of conveyance 17. A sensor 19 is arranged immediately in front of the path of movement of the cutting blade. In the preferred embodiment, the sensor 19 is an inductive sensor that

responds to metallic objects in its immediate vicinity, i.e. it can sense the passage of a metallic wrapping string. When doing so, the sensor transmits a signal to an electric control circuit (not shown) which, with a certain delay, causes the pneumatic cylinder 16 to project the cutting blade 15 in order to cut off the wrapping string when this crosses the path of movement of the cutting blade.

As appears from the drawings, the sensor 19 and the path of movement of the cutting blade are located in the space between two rotatable wheels or circular discs 20 having concentric axes of rotation. The wheels 20 are arranged at one end of a U-shaped pivot arm 21 which is pivotable about a shaft 22 acted upon by a torsional spring. This spring urges the wheels 20 towards an upper end position, as indicated by dashed lines in Fig. 4. When a bale is moved over the device, the wheels 20 will be depressed to a downwardly-pivoted position, as indicated by full lines in Fig. 4. The pivotal movement of the wheels 20 and the pivot arm 21 acts on a limit switch 23, which in turn acts on the control circuit of the cutting blade so as to prevent the blade from being projected when the wheels 20 are unloaded, in spite of the fact that the sensor 19 detects the presence of a metallic object. It is not until the wheels 20 are loaded and depressed that the cutting blade 15 can be caused to project. The cutting blade is thus prevented from projecting unintentionally, e.g. when the device is being repaired or serviced. Con¬ veniently, the required loading pressure on the wheels 20 is set so high that a human being is unable to release the cutting blade and thus risk being injured.

The inventive cutting device is arranged essentially midway between the conveyor chains 6, indicated by dashed lines in Fig. 5. The pivot arm 21 and the wheels 20 are arranged in a channel structure 24, while the cylinder 16 and the cutting blade 15 are mounted on a bracket 25 suspended from the channel structure 24. An upper protec-

tive hood 26 serves to protect the device and has an open¬ ing through which the cutting blade 15 can be projected. To enable the cutting blade to be projected at high speed, the pneumatic cylinder is suitably of a type having a thick piston rod, so that only an insignificant amount of air has to be evacuated from the top side of the piston when the cutting blade is projected. To make it possible to cut off the wrapping strings while the bale is at the same time continuously moved, the cutting blade must, immediately after being projected, be returned to the starting position, which is done by the control circuit switching, via an air valve, the air pressure from the underside of the cylinder piston to the top side thereof. The air pressure is preferably switched before the cutting blade has reached its upper end position, so that the blade is slowed down comparatively gently.

Figs 7 and 8 illustrate a preferred embodiment of the intercepting means according to the invention. As appears from Figs 1 and 3 and the foregoing description, the inter- cepting means 7 is located above the conveying path 2 in order to intercept and take hold of the wrapping strings 4 on the upper side of the bales of pulp immediately after the strings have been cut off by the cutting device 5. The intercepting means 7 is pivotable sideways by means of the pivot arm 9 and the pneumatic cylinder 14, and is verti¬ cally adjustable by means of the parallel-displacement rods 10 and the pneumatic cylinder 11. The two rods 10 are parallel and articulated, at the upper ends, to the pivot arm 9 and, at the lower ends, to the upper part of the intercepting means 7.

In the preferred embodiment, the intercepting means 7 has two substantially rectangular mounting plates 27 which are vertically oriented and spaced apart in parallel rela¬ tionship. At the upper edges, the mounting plates 27 are connected to the rods 10. An intercepting arm 28 is arranged at the lower edges of the mounting plates and partly inserted therebetween. The lower edge surface 29 of

the arm 28 serves as a guide for guiding the intercepting means onto the upper side of an incoming bale when applied thereto. For this reason, the guide surface 29 is inclined in relation to the horizontal plane so as to slope slight- ly downwards from the front end of the intercepting arm 28 towards its rear end. The intercepting arm has a plate- or sheet-like cross-section, and its rear portion forms a hook means 30. At the lower edge, the hook means 30 has an angular recess presenting a hooking edge 31 directed up- wards and obliquely backwards and facing against the direction of movement of the bales. The terminal edge of the rear portion, which extends rearwards from the hooking edge 31, is circular-arc-shaped, having a centre of curva¬ ture 32. A gripping means 33 in the form of a pivot arm with double side walls and an intermediate free space is articulated to the hook means 30, more precisely with one side wall arranged on each side of the hook means and with the hook means accommodated in the free space. The lower part of the gripping means is circular-arc-shaped, and its centre of curvature coincides with its centre of rotation and the centre of curvature 32 of the hook means. A recess is provided in the circular-arc-shaped lower part and presents a gripping edge 34 facing the hooking edge 31. The upper end of the gripping means 33 is connected to a piston rod of a pneumatic cylinder 35 located between the mounting plates 27. By means of the cylinder 35, the gripping means 33 can be pivoted between an extended or projected end position, as shown in Fig. 8, in which the recess of the hook means 30 is open, i.e. the recess of the hook means and the recess of the gripping means coincide and the hooking edge 31 and the gripping edge 34 are removed from one another, and a retracted end posi¬ tion, as shown in Fig. 7, in which the recess of the hook means is closed, i.e. the circular-arc-shaped lower part of the gripping means covers the recess of the hook means and the hooking edge 31 and the gripping edge 34 are situated close to one another.

In the area immediately in front of the hook means and the gripping means, a toothed wheel 36 is rotatably mounted on one side of the intercepting arm. The toothed wheel 36 is rotatably mounted on the end of a pivot arm 37 loaded by a torsional spring striving to move the toothed wheel 36 downwards to be applied against the upper side of the bale. Apart from the toothed wheel 36, a sensor 38 is arranged on the shaft 37. Like the sensor 19 described above, the sensor 38 is an inductive sensor for detecting metallic wrapping strings.

When a bale of pulp arrives at the station, the front part of the guide surface 29 of the intercepting arm 28 guides the intercepting means onto the upper side of the bale. While the bale continues to move, also the toothed wheel 36 and the clamping means 31 are applied against the upper side of the bale in the position illustrated in Fig. 7. Since the toothed wheel 36 is resiliently suspended, it is, in actual practice, the front circular-arc-shaped part of the clamping means 31 that will be applied against the bale, thus determining the vertical level of the inter¬ cepting means. A cutting knife 39 is provided on the front circular-arc-shaped part of the clamping means and is intended to cut up any wrapping paper on the bale. When reaching the device, a wrapping string is intercepted between two teeth of the toothed wheel 36 and maintained there against the upper side of the bale. When the wrap¬ ping string passes by the sensor 38, a control circuit records the presence of a wrapping string, and emits a signal, either immediately or with delay, to the cylinder 35 for pivoting the gripping means 33 to the position illustrated in Fig. 8. The wrapping string can be cut off before or when passing by the toothed wheel 36. When the gripping means occupies the position shown in Fig. 8, the recess in the hook means 30 is open. Then, the lower por- tion of the circular-arc.-shaped part of the hook means will be applied against or cut slightly into the bale, and the hooking edge 31 will hook the wrapping string on the

bale. After the wrapping string has been hooked, the grip¬ ping means 33 returns, e.g. after some time, to the posi¬ tion illustrated in Fig. 7, and the wrapping string is retained with sufficient force between the hooking edge 31 and the gripping edge 34 so that it can be removed from the bale even if clamped between the bale and the ^• conveyor. To enable safe retention of several wrapping strings at the same time, the hooking edge 31 is, as appears from Figs 7 and 8, inclined upwards and forwards in the direction of movement of the bales, while the gripping edge 34 is inclined upwards and rearwards against the direction of movement of the bales. Thus, a whole bundle of wrapping strings can be held between the hooking edge and the gripping edge without any opening or passage being formed between the lower tips of the hooking edge and the gripping edge.

When the gripping means 33 occupies the position shown in Fig. 8, the cutting knife 39 is removed from the upper surface of the bale and retracted into a groove 40 in the hook means 30. To enable the cutting of wrapping paper also in this position, the lower portion of the circular-arc-shaped part of the hook means 30 is provided with a cutting edge 41.

The combination of the inventive cutting device 5 and the intercepting means 7, positioned and designed as described in the foregoing, confers a number of advan¬ tages. Thus, the wrapping strings can be cut off in a first stage without being flipped away in an uncontrolled fashion, since cutting takes place on the underside of the bale in the area between the conveyor chains 6. As a result, the strings will be retained by being squeezed between the bale and the chains until the intercepting means seizes the strings and pulls them away. This means that the strings, also after being cut off, will be located by the surface of the bale where they are easily accessible to the intercepting means. Since the cutting device and the intercepting means are arranged on oppo-

site sides of the bale, the strings will be caught sub¬ stantially in the middle, and the length of the string ends hanging from the intercepting means is minimised. Conceivable Modifications of the Invention It goes without saying that the present invention may be modified in many ways within the scope of the appended claims. For instance, the invention is not restricted to the cutting of wrapping strings from a position beneath the wrapped articles, but the device might well be located above as well as beside the path of conveyance of the articles. Further, the path of movement of the cutting blade 15 need not be linear and perpendicular to the plane of conveyance of the articles, and the blade must not necessarily be projected by a pneumatic cylinder. Also, the sensor 19 does not have to be disposed in front of the cutting blade 15 against the direction of conveyance, but the sensor and the cutting blade can be arranged parallel to each other, in which case the blade can be projected without delay. Of course, the invention is not restricted to the cutting of metallic wrapping strings. If some other sensor is used, wrapping strings made of other materials can be sensed and cut off.

Also the inventive intercepting means 7 can be designed in many different ways within the scope of the appended claims. Thus, the hook means need not be in the form of a hook, but the important thing is that it presents a hooking edge facing against the direction of conveyance and extending at an angle to the outside of the articles. Neither does the gripping means 33 have to be in the form of a pivot arm, but the gripping edge 34 may be e.g. linearly displaceable towards and away from the hooking edge. Also, the intercepting means does not have to be provided above the bales, but the strings can be removed from any other, optional side. ' Instead of using a single string-removing station where the bales are turned through 90°, backed through the station and again conveyed therethrough for removal of the

wrapping strings which extend perpendicular to the first strings, as described in the foregoing, use may, of course, be made of two successive stations, making it possible to remove the strings from the bales during continuous con¬ veyance thereof, without any time-consuming stoppages.