Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – Presses or press platen structures – per se
Reexamination Certificate
1998-11-20
2001-02-06
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
Presses or press platen structures, per se
C156S515000, C156S530000
Reexamination Certificate
active
06182734
ABSTRACT:
This invention relates to an apparatus for sealing tubular or bag-shaped packaging casings, comprising tools such as crimping shears for crimping the packaging casing as well as a punch and a die for setting and closing closure clips, where the movement of one or several tools is predetermined by at least one cam track on which a scanning roller is rolling.
In known apparatuses of this type a separate cam track is generally associated to each of said tools, i.e. to the two crimping shears as well as to the punch and the die, so that the movement of these tools is predetermined individually. One cam track each is provided on a cam plate and is for instance formed by the outer flank or the inner flank of the groove in this cam plate. A scanning roller engages in said groove, which scanning roller can roll on the inner or outer flank of the groove and via a lever mechanism is connected with the respective tool. When the cam plate is put into rotation, the scanning roller scans the cam track on the cam plate and drives the associated tool via the respective lever mechanism. The movement of the tool is predetermined by the shape of the cam track on the cam plate.
In general, the movement of the above-mentioned tools is such that a filled packaging casing is first of all crimped by two crimping shears, so that there is obtained a short packaging casing neck free of filling. This packaging casing neck is subsequently elongated by spreading the crimping shears, and thereupon sealed by setting and closing two closure clips. Setting and closing the closure clips is effected by means of a punch and a die, which upon producing and elongating the neck free of filling are moved towards each other in the manner of shears, taking the neck between each other. The first of all open U-shaped closure clips are moved towards the neck by the die and bent around the neck, as soon as from the other side the punch hits the free leg ends of the U-shaped closure clips. After the packaging casing has been sealed in this way, the crimping shears are opened again and punch and die are again moved away from each other back to their starting position. The entire cycle of movement of crimping shears as well as of punch and die is controlled by the cam tracks on the motor-driven cam plates.
When the scanning roller is guided in the groove of a cam plate, it rests temporarily against the inner groove flank and temporarily against the outer groove flank during the cycle of movement of one of the tools, and in the case of a change of flank undergoes a reversal of the direction of rotation. Since there is regularly desired a high number of cycles, i.e. the production of a rather large number of sealed packages per unit of time, the number of revolutions of the cam plates as well as the accelerations which the scanning roller undergoes, are relatively high. Moreover, the force required for closing the closure clips is likewise transmitted via the cam tracks into the corresponding cam plates for punch and die. The force peaks upon closing the closure clips as well as during the reversal of the movement of the tools, which is connected with corresponding accelerations, lead to a wear of the cam track.
To avoid such wear, the German Utility Model 296 13 336 U1 proposes to drive the tools by means of one double roller lever and one cam plate each, where each of the two rollers is rolling on only one associated flank of the cam plate. In this way, the wear-promoting change of the sense of rotation of the rollers should be avoided, which occurs when during the reversal of the movement of the tools a groove-guided scanning roller changes from the inner groove flank to the outer groove flank or vice versa. Nevertheless, such an arrangement with two cam rollers is also exposed to a certain wear, for instance due to force peaks when accelerating the tools or when closing the closure clips. Moreover, between the two cam rollers and the cam tracks a clearance of 0.1 to 0.2 mm must be maintained, so that the arrangement will not jam, but can freely rotate. This clearance will even be increased by the wear caused by the force peaks. This means that the cam rollers for a short moment do not touch their associated cam track during the change of the direction of movement of the tools and come to a standstill, in order to be accelerated abruptly shortly thereafter. At this point of acceleration, an additional wear occurs.
The DE-AS 20 37 689 discloses a cam plate drive, whose cam plate is scanned on the outside by a scanning roller. The scanning roller is pressed onto the cam plate by a spring. In such an arrangement there is, however, the risk that the scanning roller is lifted off the cam plate at high rotational speeds, as the spring force is not sufficient to sufficiently accelerate the scanning roller together with the levers connected therewith, in order to follow the cam plate. However, what speaks against an increase of the spring force is the fact that the spring force must be overcome by the drive of the cam plate. Moreover, the spring force produces an additional wear at the cam plate and the scanning roller.
It is the object underlying the invention to provide a sealing apparatus with a tool drive rather free of wear, which eliminates the disadvantages of the prior art as far as possible.
This object is solved in accordance with the invention by an apparatus as described above, which in addition has a guide roller, which rolls on a separate guideway on the cam plate and by means of one elastic element each urges the scanning roller against the cam track with a bias due to an elastic deformation of the elastic element.
In such an arrangement, the scanning roller always rolls on a cam track. Thus, there is no reversal of the direction of rotation of the scanning roller. Since the scanning roller is always pressed onto the cam track, the scanning roller will not be lifted off the cam track, and the related wear will not occur. Finally, any wear will automatically be compensated by the elastic element.
What is preferred is an apparatus whose guide roller is stationarily arranged with respect to the scanning roller and has an elastically compressible running jacket, which constitutes the elastic element. The running jacket preferably consists of an elastic plastic material with a hardness of 60 to 90 Shore. In the last mentioned embodiment, the force required for moving or accelerating the tool is transmitted in a direction of movement of the tool from the cam track via the scanning roller to the tool, and in the opposite direction of movement of the tool is transmitted from the guideway via the guide roller to the tool. In the first mentioned embodiment, the force required for moving the tool is likewise transmitted in a direction of movement of the tool from the cam track via the scanning roller to the tool, but in the opposite direction of movement can also be applied exclusively by the elastic element, which presses the scanning roller onto the cam track. In any case, both the forward and the return movement of the tools are controlled by the respective cam track and scanning roller.
In an apparatus having at least one rotatable cam plate, into which at least one groove has been milled, whose groove flank forms the cam track, the opposite groove flank preferably forms the guideway,, and guide roller and scanning roller are preferably arranged on a common steering knuckle with rotational axes offset with respect to each other in parallel, so that the guide roller rolls on the guideway with a bias and presses the scanning roller onto the cam track. Such an apparatus can be realized easily and, depending on the depth of the groove, also by modifying already existing sealing machines, and it offers all the aforementioned advantages.
The offset of the rotational axis of the guide roller with respect to that of the scanning roller is preferably dimensioned such that the counter path presses in the running jacket of the guide roller by 0.5 to 1 mm, when the scanning roller rests on the cam track. A decisive aspect substantially
Ebert Detlef
Wissel Klaus
Norris McLaughlin & Marcus P.A.
Poly-Clip System GmbH & Co. KG
Sells James
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