GB2040825A

GB2040825A - Bale strapping apparatus

Info

Publication number: GB2040825A
Application number: GB7944453A
Authority: GB
Original assignee: Yhtyneet Paperitehtaat Oy
Current assignee: Yhtyneet Paperitehtaat Oy
Priority date: 1979-01-04
Filing date: 1979-12-28
Publication date: 1980-09-03
Also published as: FI57563C; GB2040825B; CH643787A5; FI57563B; DE2952606A1; SE8000057L

Abstract

A bale strapping machine has a locking device comprising a punch 17 and a cushion underneath the punch. The cushion consists of two jaws 18 which are pivotable around pivot pins 19 placed perpendicularly to the direction of movement of the punch so that anvil faces on the jaws either form a stop for the punch or can be pivoted to the sides. The jaws can be made to present their faces to the punch by pushing a wedge-ended forked support piece in between the jaws and the frame of the device. <IMAGE>

Description

SPECIFICATION Bale strapping machine The present invention is concerned with a bale strapping machine whose locking device comprises a punch movable back and forth and a cushion placed underneath the punch, which cushion preferably consists of two jaws placed on two sides of the punch, whereby the jaws are pivotable around pivot pins placed perpendicularly to the direction of movement of the punch so that the anvil faces of the jaws can be arranged into a locking position so as to form a stop face for the punch and that the anvil faces can be pivoted to the sides.

In bale strapping machines so far known the stop jaws functioning as the anvil faces for the punch and the holding jaws connected to same are moved back and forth into the locking position and to the sides of the punch by means of a shaft pivotably fastened to the jaw. Such a pushing shaft with its joints and pins is, however, during the compression step of the punch, subject to high strain, and wear of the joints and pins causes looseness and unprecision of the movements in the course of time.

A bale strapping machine in accordance with the present invention is mainly characterized in that the jaws can be pivoted from the sides into the locking position so as to form a stop face for the punch by pushing a support piece in between the jaw and the frame of the device, the face of the said support piece lying against the jaw receiving the compression force of the punch and being preferably made slanting so that the end of the support piece running ahead during the pushing movement is thinner.

When a separate support piece is used that is pushed in between the jaw and the frame, no pins and joints subject to wear are required. The slanting face of the support piece transfers the compression force of the punch to the frame of the device without joints. Even if the contact faces are worn to some extent in use, the play, nevertheless, remains precise and the joint is practically free of play. Wear does not produce any sort of play or tolerance of movement.

In a preferred embodiment of the invention, in which, for feeding and tensioning the band, a feeding and tensioning wheel provided with an uneven face and one or several counterwheels provided with a smooth face are used, the tensioning wheel and the counter wheels are arranged so that the face of the band that runs against the tensioning wheel comes to lie outwards in the strapped object. In the known machines this band face running against the uneven face of the tension ing wheel is placed against the object to be strapped.

During the tensioning step the tensioning wheel has the effect that the face of the band running against the tensioning wheel becomes rough and any anti rust coating on the band is damaged. In the device in accordance with the present invention this rough face of the band is passed outside on the object to be strapped, so that the uneven face of the band, which may possibly also become rusty later on, does not damage the package itself.

In known machines, a tensioning wheel has also been used whose diameter is considerably smaller than the diameter of the counter-wheels facing against it. In a preferred embodiment of the present invention, the ratio of the diameters of the tensioning wheel and the counter-wheel is at least 2:1.

When the tensioning wheel is larger than the counter-wheel, the tensioning force is distributed over a larger face and the notched face of the tensioning wheel does not so easily damage the face ofthe band.

The invention will be described more closely below with reference to the attached drawings, wherein Figure 1 shows the band feeding and tensioning means of the bale strapping machine in accordance with the invention as a side view, Figure 2 shows the feeding and tensioning means shown in Figure 1 as viewed from above, Figure 3 shows the band locking equipment of the bale strapping machine in accordance with the present invention as a side view, Figure 4shows the locking equipment shown in Figure 3 as viewed from ahead and partly in section with the locking jaws closed, Figure 5 shows a partial view of Figure 4 with the locking jaws open, and Figure 6 shows the locking point of the band.

In the feeding and tensioning part shown in Figures 1 and 2 a tensioning wheel 3 of steel is fastened to the drive shaft 2 mounted to the frame 1, which tensioning wheel 3 has a face provided with diagonal grooves in two directions. The drive shaft can be operated in both directions by means of an appropriate drive gear (not shown). Two parallel chains consisting of disks 5, 5' and 5" connected together by pins 6 and 6' have been fastened to the frame 1 by means of a pin 4. Two arms 7 are fastened to the pin 6" fastened to the topmost disk 5", the upper end of which arms extends through openings 8 in the frame. Above the openings 8, compression springs 9 have been fitted onto the arms 7. Above the springs there are tightening nuts lOon the arms 7.Onto the pins 6, 6' and 6", three counter-rolls 11, 11' and 11" with smooth faces have been mounted, which counter-rolls assume their positions against the face ofthetensioning wheel 3.

The ratio of the diameters ofthetensioning wheel and the counter-rolls is approximately 4:1.

For the purpose of guiding the band, there are guide plates 12 and 13 in the feeding and tensioning part between the side plates 5" of the counter-rolls at the upper parts of the plates. Between the side plates 5 at the lower parts of the plates there is a guide plate 14. The frame further includes a slit 15 for guiding the band. The lower part of the frame further includes a guide plate 16.

Figures 3 to 5 show the locking part of the bale strapping machine in accordance with the invention.

The tensioning wheel 3 is shown only schematically in connection with Figure 3. In the locking part the band is cut off, and cuts in accordance with Figure 6 are punched into the band ends fitted one above the other. The band ends are locked together when the layers overlap each other at the cuts when the band ends are being pulled apart from each other.

The principal parts of the locking means are the prick 17 of the punch and the two anvil jaws 18 placed underneath same, which jaws function as the cushion for the prick. The jaws 18 are pivotably mounted to pins 19 fastened to the frame. The edges of the jaws which face towards each other have anvil faces 20, which, when the jaws are closed, face towards the prick 17 underneath the prick. The faces 20 are shaped so that, when the band is pressed against the jaws, notches are formed in the band.

The edges of the jaws facing away from each other have brackets 21, which penetrate into openings 23 in the branch piece 22. The sides 34 facing against each other at the lower edges of the branches of the branch piece 22 have been made slanting so that the branches become thinner downwards, whereby, when the jaws 18 are in the closed position, the outer sides 33 of the jaws are in close contact with the slanting faces of the branch piece (Figure 4). A shaft 24 has been fastened to the upper part of the branch piece 22, which shaft can be moved up and down by means of a hydraulic cylinder-piston device 31.

The lower face of the punch 17 is provided with appropriate cutting means for producing the notches shown in Figure 6. One edge of the punch is additionally provided with a cutting blade 32. A transverse horizontal pin 25 has been fastened to the punch, the ends of said pin extending through the lever 26. At the punch 17, there is a vertical slit in the lever 26 through which slit the punch 17 passes. The other end 27 of the lever 26 is fitted into an opening in the frame 1 so that the lever 26 can turn around its spherical end 27. The other spherical end 28 of the lever 26 has been fitted into an opening in the arm 29. The arm 29 and together with it the other end 28 of the lever 26 can be moved up and down by means of a hydraulic cylinder-piston device 30.

Moreover, the equipment in accordance with the invention includes electrical control relays (not shown) for beginning and ending movements of different components.

The bale strapping machine in accordance with the invention operates as follows.

The band is passed in between the tensioning wheel 3 and the counter-rolls 11 between the guide plates 12 and 13 and further between the guide plate 14 and the tensioning wheel into the slit 15. The side plates 5 prevent lateral movement of the band on the tensioning wheel. The compression between the tensioning wheel 3 and the counter-rolls 11 is adjusted to the appropriate level by means of the spring 9 and the nut 10 at the upper end of the arm 7.

When the drive shaft 2 turns the tensioning wheel 3 in Figure 1 clockwise, the band is fed around the object to be strapped, placed underneath the feeding and locking equipment shown in the figure, and the end of the band is further passed from above the guide plate 16 into the locking part so that there are two layers of band one above the other in the locking part.

After the end of the band has passed by the locking part for the second time, the drive shaft 2 stops. Thereupon the cylinder-piston device 31 presses the arm 24 down, whereby the slanting ends of the branched piece 22 are pushed between the frame 1 and the contact faces 33 of the pivoting jaws 18. The jaws 18 then turn around the pins 19 so that the anvil faces 20 assume a position underneath the punch so as to constitute its stop face. The jaws constituting stop faces also include means for holding the end of the band so that, at the same time as the jaws 18 assume the locking position, the holding jaws press the end of the band so that it cannot become loose. After the end of the band has remained under the compression of the holding jaws, the tensioning wheel 3 rotates some distance in the direction opposite the feeding direction (in Figures 1 and 3 anticlockwise).Then the band is tensioned tightly around the object to be strapped.

After the tensioning step the band is cut off and locked. The cylinder-piston device 30 presses the punch 16 down against the jaws 18 by the intermediate of the lever 26. The cutting blade 32 is pressed down with the punch and cuts the band off. At the same time the punch 17 punches the cuts 35 shown in Figure 6 into the band. The cylinder-piston device 31 pulls the arm 24 up, whereby the cams 21 of the jaws 18 are turned upwards together with the branch piece 22 and the jaws 18 are opened. Thereupon the cylinder-piston device 30 lifts the arm 29 up, whereby the punch 17 also rises by the intermediate of the lever 26. The cut end of the band pulls itself off, whereby the corners in the cuts 34 at the other end of the band penetrate into the cuts at the other end of the band and lock the band. Hereupon the working cycle can start from the beginning in respect of the following object of strapping.

The invention is not only restricted to the above embodiment, but it may vary even to a considerable extent within the scope of the patent claims. The jaws 18 may be each of them of one piece or they may have replaceable wear linings. The tensioning means may also be arranged in a different way.

When the tensioning means described above is used, the proportion between the diameters of the tensioning wheels and the counter-wheels may also be different from 4:1, but in any case the tensioning wheel is larger than the counter-wheels. The number of the counter wheels may vary.

Claims

1. A bale strapping machine whose locking device comprises a punch (17) movable back and forth and a cushion placed underneath the punch, which cushion preferably consists of two jaws (18) placed on two sides of the punch, whereby the jaws are pivotable around pivot pins (19) placed perpendicu marly to the direction of movement of the punch so that the anvil faces (20) of the jaws can be arranged into a locking position so as to form a stop face for the punch and that the anvil faces can be pivoted to the sides, characterized in that the jaws (18) can be pivoted from the sides into the locking position so as to form a stop face for the punch (17) by pushing a support piece (22) in between the jaw and the frame (1) of the device, the face (34) of the said support piece lying against the jaw receiving the compression force ofthe punch and being preferably made slanting so that the end of the support piece running ahead during the pushing movement is thinner.

2. A bale strapping machine as claimed in claim 1, characterized in that the support piece (22) can be moved back and forth in the same direction as the punch (17) and that the support piece can be pushed in between the sides (33) of the jaws (18) that face away from each other and the frame (1).

3. A bale strapping machine as claimed in claim 1 or 2, characterized in that the jaw (18) is provided with a bracket (21) that extends into the opening (23) in the support face (22) and, when the support face draws itself back into its original position, is pressed against the edge of the opening, whereby the return movement of the support face makes the jaw turn itself back to the side of the punch (17).

4. A bale strapping machine as claimed in any of claims 1 to 3, which machine comprises a band feeding and tensioning wheel (3) provided with an uneven face as well as one or several counter-rolls (11) with smooth faces, placed against the tensioning wheel, whereby the band passes into the locking part between the tensioning wheel and the counterroll or rolls, characterized in that the tensioning wheel (3) and the counter-wheel or wheels (11) are arranged so that the face of the band that runs against the tensioning wheel comes to lie outwards on the object to be strapped.

5. A bale strapping machine as claimed in claim 4, characterized in that the diameter of the tensioning wheel (3) is larger than the diameter of the counter-wheel or wheels (11) so that the ratio of the diameters is at least 2:1, preferably approximately 4:1 or higher.

6. A bale strapping machine substantially as hereinbefore described with reference to the accompanying drawings.