US3218218A

US3218218A - Sealing and severing device for packaging machines

Info

Publication number: US3218218A
Application number: US221975A
Authority: US
Inventors: Sven I Bratt; Karder Terje
Original assignee: Kisab AB
Current assignee: Kisab AB
Priority date: 1961-09-11
Filing date: 1962-09-07
Publication date: 1965-11-16
Anticipated expiration: 1982-11-16
Also published as: DE1220780B; NL122944C

Description

Nov. 16, 1965 FIG I FIG 2 s. 1. BRATT ETAL 3,218,218

SEALING AND SEVERING DEVICE FOR PACKAGING MACHINES Filed Sept. '7, 1962 .I nl

Sven [Brafi and Tar e Kara'er INVE NTORS BY W @2 4 M AT TOR N EYS United States Patent 3,218,218 SEALING AND SEVERING DEVICE FOR PACKAGING MACHINES Sven I. Bratt and Terje Karder, Partille, Sweden, assignors to Kisab Aktieboiag, Goteborg, Sweden, a joint-stock company of Sweden Filed Sept. 7, 1962, Ser. No. 221,975

Claims priority, application Sweden, Sept. 11, 1961,

9,015/ 61 9 Claims. (Cl. 156-530) This invention relates to a device in packaging machines for effecting sealing and simultaneous severing of packages transversally to the feeding direction of the packages by means of two rotating rolls resiliently pressed against each other and against opposite sides of the package sheet material and having envelope surfaces designed to form narrow, mutually co-operating sealing zones parallel to the axes of the rolls, one of two co-operating zones being provided with a knife and the other with a striking bar having a counter surface perpendicular to the knife, both members extending all along the length of the zones.

A considerable inconvenience of prior machines of this type consists in that the contact pressure of the rolls againstthe package sheet material is reduced during the severing operation due to the fact that the knife and the striking bar are bearing to a considerable part of the contact pressure during the severing operation, which will give rise to poor seals on both sides of the line of cutting. Compensation by increasing the pressure on the rolls to a value required for good sealing during the cutting operation will result in too great contact pressure during the sealing operation. In order to avoid these irregularities in sealing, packaging machines of similar types having two sealing jaws which are movable into engagement with opposite sides of the package material as well as along the feeding direction of the packages are often provided with a knife which is slidably fitted in a slot in one of the jaws which knife when severing the package material is arranged to enter a slot in the other jaw aligned with the slot in the first jaw. The sealing performed by means of such a sealing and severing device is not entirely satisfactory because no sealing at all is obtained near the line of cutting where the slots are located.

The object of the invention is, therefore, the provision of a package machine in which said inconveniences are avoided in a simple and satisfactory manner.

According to the invention a sealing and severing device for packing machines is provided for effecting sealing and simultaneously therewith severing of packages transversally to the feeding direction of the packages by means of two rotating rolls resiliently pressed against each other and against opposite sides of the package sheet material and having envelope surfaces designed to form narrow, mutually co-operating sealing zones parallel to the axes of the rolls, one of two co-operating zones being provided with a knife and the other with a striking bar having a counter surface perpendicular to the knife both members extending all along the length of the zones, characterized in that the knives and/or the striking bars are slidably fitted in radial slots in the rolls and are provided with end portions protruding from the end walls of the rolls which end portions at the severing moment move into engagement with and are pressed radially outwards by means of two cam surfaces which are journaled in the frame movable in the direction perpendicular to the tangential plane of the rolls against the urge of resilient members.

Thus the rolls are operated independent of the knife and the striking bar and it is possible to adjust the contact pressure of the rolls to a value which is suitable for ob- Patented Nov. 16, 1965 taining a fully satisfactory seal. During the severing operation a suitably adapted force is supplied to the knife and the striking bar by means of the cam surfaces without influencing the contact pressure of the rolls.

In a sealing and severing device according to the invention it is possible to obtain an improved severing and a reduction of the force necessary for the severing in a very simple manner, as will be apparent in the following, by imparting to the knife and the striking bar, respectively, a tilting motion at severing in which case the edge of the knife and the striking bar are suitably formed slightly crooked, so that these members touch each other in a point of tangency which due to the tilting is displaced along the line of severing.

A specific embodiment of the invention is shown by way of example in the accompanying drawings in which:

FIGURE 1 shows the rolls in longitudinal section and arms located outside the end walls of the rolls supportingthe rolls and the cam surfaces, and

FIGURE 2 shows a view of one of the end portions of the rolls, which is equal to the other end portion.

The rolls 1 and 2 are in this embodiment arranged one above the other. The lower one 1 is rotatably journaled directly in the frame 3 by means of two arms 4 which are fixedly mounted in the frame on both sides of the roll and on which the shaft pivots 5 of the roll are journaled. The shaft pivots 6 of the upper roll 2 are rotatably journaled on two lever arms 7 located on both sides of the roll, which arms are pivoted on the frame 3 by means of the shaft 8. On this shaft 8 two further arms 9 are pivoted on both sides of the roll 2, each of which arms supports a roller 11 rotatably journaled on the shaft 10. The rolls are provided with envelope surfaces, which form mutually co-acting

sealing zones

12, 13 and 14, 15, and along the middle lines of the zones the rolls are provided with radial slots 16, 17, 18, 19 which extend straight across the width of the rolls. In the bottom of the slots 16 and 18 striking bars 20 are fixedly mounted and in the slots 17 and 19 knives 21 are slidably fitted having end portions protruding from the end walls of the roll 2. The free ends of the

arms

6 and 9 are resiliently attached to the arms 4 by means of

rods

22 and 23 and compression springs 24 and 25 the pressure of which is adjustable by means of nuts 26 and 27.

As the rolls 1 and 2 are rotated by means of a drive mechanism, not shown, a series of the units to be packaged 28 placed in spaced-apart relationship and enveloped by a flexible, sealable sheet wrapper material is advanced between the rolls 1 and 2 in synchronism with the rotation of the rolls and with the edge portions of the sheet material pressed between the cylindrical end portions of the rolls. The radius of the rolls 1 and 2 and the number of sealing zones are so adapted that seals are obtained intermediate the individually packaged units. At every sealing operation the end portions of a knife 21 pass by under the rolls 11, which are located in a distance from the shaft 7 so adapted that the knife is pressed outwards and brought into engagement with the striking bar simultaneously present under the knife and is pressed against this by means of the rollers under compression of the springs 25.

In the embodiment shown the striking bars 20 are countersunk somewhat below the surface of the sealing zones which facilitates the cutting operation in that the package sheet material when moved downward towards the striking bar 20 by the knife 21 and clamped along the edges of the slots 16, 18 becomes subjected to tension simultaneously with the cutting. In a further embodiment of the invention it is possible to impart to the knife a tilting motion in the plane of the knife in a very simple way by 10- cating the rollers somewhat displaced in relation to each other in the direction of rotation of the rolls.

The knives 3 or the striking bars are suitably formed slightly crooked in this case so that a knife and a striking bar touch each other in a contact point which due to the tilting of the knife continuously is displaced across the seal.

The invention is, of course, not limited to the embodiment shown but should be regarded as including modifications and variations thereof within the scope of the invention as claimed. Thus, the arms 9 may be provided with fixedly mounted cam surfaces instead of rollers 11. Further the roll 1 and the striking bars 20 may be resiliently journaled in the same manner as the roll 2 and the knives 21. Besides, in some cases, the rolls may be arranged to make a reciprocating motion of turning eventually in combination with bringing the rolls apart during the backward motion of the rolls.

We claim:

1. A sealing and severing device for a wrapper with spaced contents therein comprising a frame, two uniformly rotating rolls in said frame between which said wrapper is fed, a spring yielding bearing arrangement for said rolls, a sealing member on each roll having a radially extending slot therein dividing said members into each two spaced sealing zones extending parallel to the longitudinal axis of each roll, a knife blade slidingly mounted in said slot of one of said members, a striking bar mounted in the other of said members, said knife blade and striking bar severing said wrapper between the seals made by said zones between said spaced contents, said knife blade having the ends thereof protruding from the end Walls of its roll, means mounted in said frame in resilient bearing members cooperating with said ends for operating said knife blade for displacing it radially outwards in said slot.

2. A sealing and severing device for a wrapper with spaced contents therein comprising a frame, two uniformly rotating rolls in said frame between which said wrapper is fed, a spring yielding bearing arrangement for said rolls, a sealing member on each roll having a radially extending slot therein dividing said members into each two spaced sealing zones extending parallel to the longitudinal axis of each roll, a knife blade mounted in said slot of one of said members, a striking bar slidingly mounted in said slot of the other of said members, said knife blade and striking bar severing said wrapper between the seals made by said zones between said spaced contents, said striking bar having the ends thereof protruding from the end walls of its roll, means mounted in said frame in resilient bearing members cooperating with said ends for operating said striking bar for displacing it radially outwards in said slot.

3. A sealing and severing device for a Wrapper with spaced contents therein comprising a frame, two uniformly rotating rolls in said frame between which said wrapper is fed, a spring yielding bearing arrangement for said rolls, a sealing member on each roll having a radially extending slot therein dividing said members into each two spaced sealing zones extending parallel to the longitudinal axis of each roll, a knife blade slidingly mounted in said slot of one of said members, a striking bar slidingly mounted in said slot of the other of said members, said knife blade and striking bar severing said Wrapper between he seals made by said zones between said spaced contents, said knife blade and striking bar having the ends thereof protruding from the end walls of said rolls, means mounted in said frame in resilient bearing members cooperating with said ends for operating said knife blade and striking bar for displacing them radially outwards in said slots.

4. A sealing and severing device as claimed in claim 1, wherein said means coacting with the ends of said knife blade are positioned mutually displaced in the direction of rotation of the rolls to impart to the knife blade a tilting motion in the plane of said slot at the severing operation.

5. A sealing and severing device as claimed in claim 4, wherein the edge of the knife blade is slightly crooked in the plane of said slot.

6. A sealing and severing device as claimed in claim 1, wherein said means cooperating with said ends are mounted each on a spring-loaded lever arm pivoted on a shaft parallel to the axes of said rolls.

7. A sealing and severing device as claimed in claim 6, wherein one of said rolls is journaled on two springloaded lever arms pivoted on said shaft.

8. A sealing and severing device as claimed in claim 7, wherein the free end portions of all the lever arms are lengthened and resilient members having means for adjusting the springforce are mounted between the lengthened portions of said lever arms and said frame.

9. A sealing and severing device as claimed in claim 1, wherein said means cooperating with said ends comprise freely rotatable rollers eccentrically journaled in relation to said rolls.

Claims

1. A SEALING AND SEVERING DEVICE FOR A WRAPPER WITH SPACED CONTENTS THEREIN COMPRISING A FRAME, TWO UNIFORMLY ROTATING ROLLS IN SAID FRAME BETWEEN WHICH SAID WRAPPER IS FED, A SPRING YIELDING BEARING ARRANGEMENT FOR SAID ROLLS, A SEALING MEMBER ON EACH ROLL HAVING A RADIALLY EXTENDING SLOT THEREIN DIVIDING SAID MEMBERS INTO EACH TWO SPACED SEALING ZONES EXTENDING PARALLEL TO THE LONGITUDINAL AXIS OF EACH ROLL, A KNIFE BLADE SLIDINGLY MOUNTED IN SAID SLOT OF ONE OF SAID MEMBERS, A STRIKING BAR MOUNTED IN THE OTHER OF SAID MEMBERS, SAID KNIFE BLADE AND STRIKING BAR SEVERING SAID WRAPPER BETWEEN THE SEALS MADE BY SAID ZONES BETWEEN SAID SPACED CONTENTS, SAID KNIFE BLADE HAVING THE ENDS THEREOF PROTRUDING FROM THE END WALLS OF ITS ROLL, MEANS MOUNTED IN SAID FRAME IN RESILIENT BEARING MEMBERS COOPERATING WITH SAID ENDS FOR OPERATING SAID KNIFE BLADE FOR DISPLACING ITRADIALLY OUTWARDS IN SAID SLOT.