CA2144525C

CA2144525C - Hoop-casing machine with a hoop guiding frame

Info

Publication number: CA2144525C
Application number: CA002144525A
Authority: CA
Inventors: Georg Lang; Berthold Buhrle
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-09-14
Filing date: 1993-09-11
Publication date: 2006-07-11
Anticipated expiration: 2013-09-11
Also published as: DE4230730A1; DE4230730B4; KR100268775B1; CN1039690C; CN1085514A; WO1994006683A1; CA2144525A1; KR950703463A

Abstract

A hoop-casing machine has a hoop guiding frame that forms a channel (22) with a rectangular cross-section twisted in determined longitudinal sections. The frame consists of fixed (18, 2d, 27) and mobile (19, 25, 28) parts, the relative movement of which in controlled and guided manner allows the channel (22) to be closed or opened for enclosing and stretching the hoop in the longitudinal direction. In order to make production easier and to increase reliability in operation, a rectilinear mobile frame part (19, 25, 28) is provided which forms together with a fixed frame part (18, 24, 27) a twisted channel section. Preferably, one of both frame parts (19) has a circular arc-shaped full cross-section, in which the channel cross-section (20) with a long radial center line is cut, whereas the other corresponding frame part (18) has a circular arc-shaped hollow cross-section with the same or a larger radius.

Description

HOOP-CASING MACHINE WITH A HOOP GUIDING FRAME
The present invention relates to a strapping machine of the kind that are used, for example, to strap bundles of newspapers or packages. It is preferred that the band consist of a metal or a tough plastic, and it is used in varying widths and thickneases.
A special feature of such a machine is that the band guiding frame and the channel that is incorporated within it, which establishes the shape of the strapping band loop when the band is installed, follows a spatial, i.e. three-dimensional path. If, after the conclusion of the strapping process the band is looped tightly around the object that is to be banded, it forms a flat loop, as is known. The plane that is defined thereby is referred to as the strapping plane. In the case of the machines that are discussed herein, when tightened and after leaving a band guiding channel, the band is deflected or reformed into the strapping plane. It changes from the spatial shape into the final flat shape. Because of this the multi-part band guiding frame, which, as a whole, is stationary, can be so configured that the item that is to be packaged can pass through it on a rectilinear feed path without rotation and, despite this, the strapping plane lies in the direction of feed.

The non-stretchable strapping materials used for this cannot be guided in a curve if the axis of curvature of the curve is perpendicular to the plane of the tape. If one farces the tape into such a curved path, it twists, i.e., it twists about its longitudinal axis. For this reason, band guiding frames that are not flat are complex structures. Of necessity, the actual curve of the path includes twisted sections of the channel. However, these demand considerable technical effort for gates and other moving parts of the frame that are used to open and close the channel.
A strapping machine of the type discussed in the introduction hereto is described in DE-OS 41 00 276. This is a cross-strapping machine, although the disadvantage referred to above is also encountered if one imagines the transverse frame as having been eliminated. The~band guiding frame that brings about the longitudinal strapping has a number of moving frame parts, all of which have their own dedicated activating solenoids.
Another machine of this kind has been proposed in patent application DE P 41 39 571.9. In this, the upper part of the band guiding frame forms a flat frame so that this section at least can be made and opened in the conventional way.
In the case of simple cross-strapping machines, the conventional technology is such that the whole of the band guiding frame is divided into two parts, parallel to the plane of the loop, with one of the two parts incorporating a groove and the moving part resting on the fixed part in a movement that is directed perpendicular to the plane of the frame. Thus, the groove with its cover forms a band guiding channel.
It is the task of the present invention to create a simple and reliable longitudinal strapping machine that is safe to operate.

Proceeding from a strapping machine of the type described in the introduction hereto, according to the present invention, this problem has been solved in that a frame part that moves rectilinearly is provided and this, in conjunction with a fixed frame part, forms a twisted channel section. Fundamentally, the cross-sections of the two parts of the band guiding frame can be so formed that the opposing contact surfaces, which form the separating gap of the channel, are twisted planes. However, the larger the angle of twist and the more curve the path followed by the channel, the mare difficult it becomes to manufacture such frame parts. An advantageous solution to this problem is such that the largest possible sections of the band guiding channel be formed in only two parts, arid these move rectilinearly towards each other and away from each other in order to permit the elimination of bearing points and individual actuating systems.
The fewer the individual parts that are incorporated, the greater the security against the unintended egress of the strapping band from the band guiding channel.
However, in the case of twisted channel sections having a simple curved, three-dimensional path, the manufacture of the parts of the band guiding frame requires considerable expenditures. For this reason, in order to simplify production and to improve the fit of the parts relative to each other, it is proposed that the one part, in particular the moving frame part, has a circular arc cross-section from which the cross-section of the channel is machined out with a longitudinal mid-line axis that runs radially and in that the other frame part has a circular arc-shaped hollow cross-section that is of equal or greater radius. Frame parts that are formed in this way are particularly simple to manufacture. They lie snugly inside each other and the hollow curved frame part encloses the groove very neatly, no matter what their position may be with respect to the angle~of twist. This basic shape is also suitable for sections of the band guiding frame, the channel of which forms an arc and which is twisted back in the entry area of the arc in the 27$44-25 direction of torsional rotation and in the outlet area of the arc in the other direction of twist. When this is done, the channel can be guided in a 90' or an even wider arc and the range of the angle of twist can be up to 90° or more if this facilitates the transition of the band into the strapping plane. The cross-section of the hollow curved plane part can vary along the length of the channel. To the extent that its edge areas are not required to cover the groove or to form the channel, they can be cut off so that they do not hinder the movement of the band when it is being tightened. The circular arc-shaped cross-section that has been referred is, in the simplest case, a fully circular cross-section. In this case, when manufacturing the grooved part, one starts with a round profile material which, either prior to or after the groove has been milled into it, is bent into the desired shape. The round profile material can then be welded or bolted to suitable stiffening elements. On the other hand, a rail or a flat material with an appropriate rounded edge is~also suitable. Apart from metal, plastics can also be used as the working material, when the plastic profile can be reinforced and mechanically stiffened by means of a metal bar.
In order to produce a development of the present invention that is particularly advantageous from every standpoint, it is proposed that the overall band guiding frame of a longitudinal strapping machine as described in German patent application P 41 39 571.9, whose path consists of a single fixed and a single moving part, the latter being guided in the approximate direction of the bisecting line of the, angle of the horizontal curve of the lower frame section. When this is done, the fixed and the moving parts can be assembled from frame sections of varying cross-sections, when the simplest cross-section form with which the technical operations demands can be met will be selected. In particular, the band guiding channel must be "tight", i.e., when the band is installed it must not be able to escape from the channel through any small opening. In addition, it must neither jam or bind, and it must not be hindered as it emerges after the channel has been opened. From this standpoint, it is proposed that the 5 band guiding frame be formed with the above-discussed spatial path, at least in the sections of the horizontal curve with torsion in both directions, with frame parts that are of circular cross-section. However, additional curved or straight frame sections with twisted or straight band guiding channels can also be used. Preferably, the whole of the band guiding channel is made of such one-piece parts.
In accordance with one aspect of the present invention, there is provided a strapping machine for strapping a band around a package including: a band guiding frame having fixed frame parts and moveable frame parts relative to the fixed frame parts and forming a band guide channel for receiving the band therein, said channel being of a rectangular cross section and twisted in longitudinal sections; and wherein the relative movement of said fixed and moveable frame parts allows the channel to be opened or closed for introducing and tensioning the band in a longitudinal direction; characterized in that a moveable frame part is moveable in a rectilinear direction with respect to a fixed frame part, and wherein the moveable frame part and the fixed frame part, together form a twisted channel section.
Finally, the present invention is not restricted to band guiding frames having cross-sections with rectilinear or curved lines of contact. The lines of contact or lines of separation can be so laid out that the channel cross-section on one long side is divided diagonally, the lines of separation then standing essentially perpendicular to the middle longitudinal line.

5a One embodiment of the present invention with band guiding frames of various cross-section will be described in greater detail below on the basis of the diagrammatic drawings appended hereto. These drawings show the following:
Figure 1: a plan view of the essential parts of a longitudinal strapping machine with the band guiding frame closed;
Figure 2: cross-sections of the band guiding frame, each of which is viewed in the direction of insertion of the band;

Figure 3: a view of the machine as seen~opposite to the direction of feed;
Figure 4: additional cross-sections to the ones shown in Figure 3; ' Figure 5: a side view of the machine shown in Figure 1;
Figure 6: a plan view as in Figure 1 with the band guiding plane open;
Figure 7: some of the cross-sections shown in Figure 6:
Figure 8: some examples of cross-sections of another band guiding frame.
Figures 1, 3, and 5 are diagrammatic drawings of a band guiding frame which, put simply, consists of an S-shaped, approximately horizontal lower section, two vertical sections, and a horizontal upper section that crosses diagonally over the lower section. In addition, Figure 1 shows delivery means, here in the form of two conveyor belts 1 and 2 which are shown by dotted-dashed lines.
Rams or other conveyor elements could be used. The direction of movement is indicated by an arrow 3. Of course, the movement could also be in the opposite direction. The conveyor means are arranged next to each other and offset relative to each other in the direction of movement, and extend through the band guiding frame. Figure 1 shows that the S-shaped lower part of the frame is not covered by the conveyor means, so that the strapping band can emerge upwards through a slot that conforms to the shape of the lower part of the frame, said slot being in the conveyor table (not shown herein), and between the conveyor means.
Finally, an object 4 that is to be packed and which is more or less cuboid is indicated by dotted-dashed lines in the strapping position.
The lower section of the band guiding frame consists of two 2I4~~~~

arcs 5 and 6 that form 90° curves to the right and the left, and leave a gap 7 open between them. Here there is a fastening head, of which only the plate-shaped transversely moveable upper section 8 is shown. On the section between the fastening head and the beginning of the curve 7, which is rectilinear as seen from above, the band guiding frame is inclined (stepped) slightly downwards as can be seen most clearly from Figure 5. An arc 9 that leads vertically upwards is adjacent to the horizontal arc 6. This is followed by a vertical section 10 that is twisted to the left, an arc 11, the upper rectilinear section 12, an arc 13 that leads downwards, a vertical section 14 that is twisted to the left, and, finally, an arc 15 that becomes the horizontal arc of the lower section. A short section that is bent slightly upward is adjacent to the arc 5 and this opens out once again into the fastening head.
The strapping band 16 that is shown only in Figure 5 is installed in the delivery system with the plane of the band parallel to the plane of movement, and it passes through the sections of the band guiding frame in the sequence set out above.
Its front end 17 finally emerges from the arc 5 after which the fastening head tightens the loop of strapping, cuts off the feed end and then joins the ends to each other. As can be seen, in particular, from Figures 1, 2, 6, and 7, the arc 6 and the previous bent section consist of a fixed part 18, which in this example is shaped in the form of a plate, but which can also be in the form of a bar provided with another suitable attachment profile, and a moving part 19 in the form of a round-profile rod with a radial longitudinal groove 20. This groove is covered by the hollow cylindrical surface 21 of the part 18 on its narrow side and thus y 2144~2~

forms the band guiding channel 22 that is of rectangular cross-section and is indicated in Figure 1 by dashed lines.
Within the area of the arc the guide 20 is twisted in the sense that it rotates along the length of the round profile rod, about the middle axis of said rod, which is to say (viewed in the direction of insertion of the band) first by 90° to the right, as is shown in the cross-sectional drawings a, b, and c in Figure 2, and towards the end of the curve once again by 90° to the left.
The shape of the concave surface 21 of the part 18, the radius of curvature of which is somewhat greater than that of the round profile rod, follows the round profile rod along the whole length, although the upper edge areas are cut off there, where they are not required to cover the groove 20. This can be seen from a comparison of the cross-sections a and c of Figure 2, and the plan view. Thus, the upper edge 23 of the part 18 extends, in plan view, obliquely over the round profile rods 19 and back once again, which means that the fixed part 18 of the round profile rod 19 partially covered as if with a rounded, flat tongue. Thus, when assembled with the part 18, the round profile rod 19 is specifically guided and properly seated.
The adjacent 90° arc 9 as well as the adjoining sections of the band guiding frame as far as section 15 consists of a fixed part in the form of a flat steel bar 24 and a moving part in the form of a square profile rod 25. It is preferred that the square profile rod be of a suitable smooth plastic, e.g., polyethylene.
On the side that faces the flat steel bar 24 there is a longitudinal groove 26, and this has dimensions that identical to those of the groove 20 and, in conjunction with the flat steel bar 25, continues the band guiding channel 22 without any interruption. The twisting and the bending of the adjacent band guiding frame sections are effected by the two parts 24 and 25 together. In this example, the plane of the upper sections 11, 12, and 13 of the band guiding frame forms an angle approximately 35° with the delivery system in this example. Accordingly, the angle of twist of the two sections 10 and 14 is approximately 55°. Finally, the arc 15 continues to channel into the lower frame .
Apart from the opposite paths of the curves, the arc 5 is configured like the arc 6. However, the fixed part 27 forms an inside curve and the groove in the associated round profile rod 28 forms an outside curve. Here, too, the part 27 overlaps the round profile rod and thus ensures that there is a guide when the parts are assembled and also that the groove is securely covered.
In order to make it easier to understand the diagrammatic drawings that have been described, all of the connecting, stiffening, and guide elements have been omitted, even those that are important for the design and practical realization of the present invention. Thus, the round profile rods are welded or bolted to rails or an appropriate framework. In order that they are connected to each other and fixed in their three dimensional position. Because of its greater stiffness, it is preferred that angle-steel profiles be used in the place of the flat steel 24.
It is, however, important to mention that all the sections of the fixed and of the moving frame parts that have been described above be connected rigidly to each other in a suitable manner and thus form a rigid structure. The moving part that is assembled in this way is supported in slide guides so as to be able to slide, in such a way that it can move back and forth in the direction of the line that bisects the angle of the curve 5 and 6, as is indicated by the arrows 29 (the direction in which it opens) and 30 (the direction in which it closes). Figure 6 shows the open position and the direction of closing. The fact that the moveable and fixed frame part are moved back and forth diagonally to their longitudinal dimension and as a further consequence, the two associated parts are spaced apart from each other by different distances is unimportant from the standpoint of function. It is, however, important that after the band guiding channel has been opened, the strapping band has enough room to move out of the channel when being tightened. This has been ensured, as is shown in Figure 6. In this example, the opening movement is produced by four pneumatic cylinders and is effected obliquely. When this is done, the form in which the band guiding frame is made ensures that the strip moves into the strapping plane that is determined by the fastening head without the need for any guide elements or ejectors.
An alternative for the configuration of the cross-section of the two band guiding frame parts is shown in Figure 8. Here, are two interacting slides 31 and 32 and the band guiding channel 33 is formed on their contact surfaces. In this case, a broad side and a narrow side of the band guiding channel 33 is formed on each of the two slides. The remaining contact surface areas form a separation gap 34 that is perpendicular to the surface of the band which is important for the smooth entry of the band. In the four cross-sections 1 to 0 that are shown, the band guiding channel is shown to twist through 90°. Because of the partially wedge-shaped configuration of the contact surfaces, here too, there is good guidance of the slides as they move towards each other and a precise seating in the closed position of the band guiding channel so that it is ensured that the band enters smoothly and without friction.

~1~4~~~

1 Delivery means 2 Delivery means 3 Arrow (direction of movement) 4 Object to be packed Arc, right 6 Arc, left 7 Gap 8 Upper part of the strapping head 9 Arc Twisted section 11 Arc 12 Upper section 13 Arc 14 Twisted section Arc 16 Strapping band 17 End of band 18 Part 19 Round profile rod Groove 21 Hollow cylindrical surface 22 Band guiding channel 23 Upper edge 24 Flat steel Square profile rod 26 Groove 27 Part 28 Round profile rod 29 Arrow (direction of opening) Arrow (direction of closing) 31 Slide 32 Slide 33 Band guiding channel

Claims

CLAIMS:

1. A strapping machine for strapping a band around a package including:
a band guiding frame having fixed frame parts and moveable frame parts relative to the fixed frame parts and forming a band guide channel for receiving the band therein, said channel being of a rectangular cross section and twisted in longitudinal sections; and wherein the relative movement of said fixed and moveable frame parts allows the channel to be opened or closed for introducing and tensioning the band in a longitudinal direction;
characterized in that a moveable frame part is moveable in a rectilinear direction with respect to a fixed frame part, and wherein the moveable frame part and the fixed frame part, together form a twisted channel section.

2. A strapping machine as defined in claim 1, characterized in that the moveable frame part incorporates a contact surface in the form of a twisted plane and a groove that follows the axis of twist, the depth of which corresponds to the greatest width of the channel cross-section; and in that the associated fixed frame part incorporates a contact surface that corresponds to the contact surface of the moveable frame part.

3. A strapping machine as defined in claim 1, characterized in that the channel section follows a curved path.

4. A strapping machine as defined in claim 1, characterized in that the channel section follows a three dimensional path.

5. A strapping machine as defined in claim 1, characterized in that the moveable frame part has a circular arced solid overall cross-section from which the channel cross-section with a radial longitudinal middle axis is machined out; and in that the fixed frame part associated with said moving frame part has a circular arc-shaped hollow cross-section with an identical or greater radius.

6. A strapping machine as defined in claim 5, characterized in that the fixed frame part and moveable frame part form a channel section that defines an arc and is twisted in the entry area of the arc in one direction of rotation and in the exit of the arc in the other direction of rotation.

7. A strapping machine as defined in claim 6, characterized in that the arc is a 90°-arc and the angle of twist is about 90°.

8. A strapping machine as defined in claim 1, wherein the band guiding frame has a horizontal lower section, a first and second vertical section, and a horizontal upper section that crosses diagonally over the lower section, wherein said lower section has first and second opposing curves and a fastening head situated therebetween forming a horizontal plane along a channel wide side;
wherein a section immediately adjacent the fastening head is inclined downward toward the beginning of the first curve and a section immediately adjacent the fastening head is inclined upward toward the beginning of the second curve; and wherein the overall path of the band guide frame comprises:

(a) a descending length from the fastening head towards the first curve and along said first curve torsioned in one and then an opposite direction in the horizontal plane;
(b) a 90° arc adjacent said first curve, connecting said lower section to said first vertical member, said first vertical member twisting to the left by approximately 35° and curving 90° into said upper horizontal section;
(c) a rectilinear section along said upper horizontal section traversing across the fastening head said upper horizontal section curving 90° downwardly into said second vertical member, said second vertical member twisting to the left by approximately 35° and curving 90° into the lower horizontal member to join the second curve; the second curve with torsion in one and the opposing direction in the horizontal plane, and (d) an ascending length adjacent said second curve, ascending into the fastening head, as at the exit, consisting of the fixed and the moving part, the moving part being guided horizontally and in the approximate direction of a line that bisects the angle formed by the opposing curves.

9. A strapping machine as defined in claim 8, characterized in that the overall band guiding frame is formed with frame parts that are of circular cross-section.

10. A strapping machine as defined in claim 2, characterized in that in the area of contact, the fixed and the moving frame parts are formed in such a way that the channel cross-section is divided on one of a long side and diagonally, the remaining contact areas forming separation gaps strapping essentially perpendicular to the plane of the band.