Package making – Apparatus for forming or partially forming receptacle and... – Forming a pocket or pouch by folding and side sealing
Reexamination Certificate
1999-05-20
2001-10-16
Kim, Eugene (Department: 3721)
Package making
Apparatus for forming or partially forming receptacle and...
Forming a pocket or pouch by folding and side sealing
C053S389100, C053S389200, C242S421400
Reexamination Certificate
active
06301862
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of adjusting the tension applied to a sheet, more particularly a method of adjusting the tension applied to a sheet pulled out of a sheet roll in a stepwise manner according to the changing diameter of the sheet roll, and a device for carrying out the method.
One conventional drug packaging device includes a sheet feed unit rotatably supporting a rolled sheet of heat-fusible packaging paper, and a sealing device provided in a feed path through which the packaging sheet is unwound and fed. Upstream of the sealing device, the sheet is folded in half, drugs are supplied, and the sheet is heat-sealed in the width direction and along the edges by the sealing device to seal the drugs.
When the packaging sheet runs out, a new paper roll is set in the paper feed unit, and the new sheet is unwound and fed. When the sheet is fed, it has to be tensioned uniformly so that the sealing position will not deviate due to inaccurate folding of the sheet. But actually, the tension applied to the sheet changes gradually because the diameter of the paper roll changes gradually as the sheet is unwound.
Examined Japanese utility model publication discloses a sheet tension adjusting device which can apply uniform tension to the sheet even when the diameter of the sheet roll changes. The sheet tension adjusting device disclosed in this publication has a roll support cylinder on which is detachably mounted a sheet roll. A plurality of roll diameter detection sensors are provided at the side of the sheet roll. Signals from these detection sensors are used to control the electromagnetic force produced by an electromagnetic brake provided in the roll support cylinder so that the baking force decreases stepwise as the roll diameter decreases.
With this conventional sheet tension adjusting device, the sheet length of the sheet, which changes as the sheet is unwound, is detected stepwise by the roll diameter sensors arranged in the diametric direction of the roll. Thus, when the roll diameter decreases to a point where the detection sensor rank changes, the braking force rank of the electromagnetic brake will fluctuate up and down for every rotation due to deviation of the axis of the core shaft, the weight of the sheet, or winding strain.
If this happens, the sheet edges cannot be aligned accurately when the sheet is folded in half. Complete packaging is thus impossible. Since the braking force rank changes sharply, the sheet may suffer a laceration in the width direction.
Light reflecting type detection sensors have a problem in that they are more likely to malfunction. Packaging sheets used for a drug packaging device include semi-transparent, or transparent heat-fusible paper and many other kinds of paper. If the end position of such a sheet changes, light is reflected differently, making it impossible to detect the reflected light as a signal. This deteriorates detecting accuracy. Further, it tends to meander under the influence of humidity variations. Detection accuracy may deteriorate due to uneven end faces.
A thermal printer is usually provided upstream of the position where the sheet is folded in half for printing the packaging sheet. If the sheet vibrates, its printing dots may chip, or the durability of a remainder indicator lamp may deteriorate.
An object of this invention is to provide a method and a device of adjusting the tension in a sheet which is free of the problems of a conventional method of adjusting the tension in a sheet.
SUMMARY OF THE INVENTION
According to this invention, there is provided a method of adjusting the tension in a sheet comprising bringing a braking means into engagement with a roll support cylinder rotatably mounted around a nonrotatably supported support shaft, measuring the length of a sheet being fed from a roll of paper mounted on the roll support cylinder with a sheet length measuring sensor, calculating the winding length of the roll of paper after the sheet has been fed by subtracting the sheet length measured by the sheet length measuring sensor from a prestored maximum sheet length of the roll, calculating the current diameter of the roll based on the winding length of the roll and the thickness of the sheet, and adjusting the tension in the sheet by controlling the braking force of the brake means in a stepwise manner according to the current diameter of the roll.
The sheet length measuring sensor may be a sheet feed length detection sensor provided in a sheet feed path, or an angle sensor provided on the roll support cylinder for determining the sheet feed length based on the rotation angle of the roll support cylinder.
There is also provided a method of adjusting the tension in a sheet comprising bringing a braking means into engagement with a roll support cylinder rotatably mounted around a nonrotatably supported support shaft, detecting the length of a sheet being fed from a roll of paper mounted on the roll support cylinder with a sheet length measuring sensor, detecting the rotation angle of the roll support cylinder with an angle sensor, calculating the current paper length of the roll based on the sheet length or the rotation angle measured by either sensor, and adjusting the tension in the sheet by controlling the braking force of the brake means in a stepwise manner according to the diameter of the roll corresponding to the current paper length of the roll. length measuring sensor, detecting the rotation angle of the roll support cylinder with an angel sensor, calculating the current paper length of the roll based on the sheet length or the rotation angle measured by either sensor, and adjusting the tension in the sheet by controlling the braking force of the brake means in a stepwise manner according to the diameter of the roll corresponding to the current paper length of the roll.
In the first method, the sheet length is measured by a single sheet length measuring sensor. Thus, in this method, it is essential that the full sheet length of the paper roll be known. This length is thus stored in a memory, and the current roll length is calculated by substracting the sheet feed length from the full roll length stored in the memory.
Such a full roll length does not necessarily have to be an actually measured value but may be approximately calculated based on the roll diameter and the sheet thickness. Such an approximately calculated value is sufficient to adjust the sheet tension because the braking force is adjusted roughly in a stepwise manner according to the changing diameter of the paper roll. Thus, even if the full roll length is not the full length of an intended end product, for example, even if the roll has been half used, it is possible to calculate the current roll length if the full roll length and diameter are known.
Based on the thus determined current roll length and the sheet thickness, the current roll diameter is calculated. The current roll diameter thus obtained is used to adjust the sheet tension by selecting an optimum brake force is a stepwise manner.
In the third method, signals are detected by the sheet length measuring sensor and the angle sensor. Based on the change in one signal relative to the other, a change in the roll length is directly measured.
By correlating a predetermined range of change in roll length with a change in the roll diameter beforehand, it is possible to select a stepwise control level of the braking force simply by detecting the change in the roll length. Thus, it is possible to adjust the sheet tension to an optimum level for each stage by controlling the braking force according to the roll diameter.
The third method according to this invention comprises carrying out a special mode before a normal mode in which the tension in the sheet is adjusted while the sheet is being fed, the special mode including calculating the paper winding length of the roll based on the signals from the sheet length sensor and the angle sensor in the same manner as in the normal mode by an inching operation in which the sheet is intermittently fed by a predet
Amano Hirokazu
Etou Naomichi
Nose Hiroshi
Yasunaga Itsuo
Yuyama Shoji
Kabushiki Kaisha Yuyama Seisakusho
Kim Eugene
Wenderoth , Lind & Ponack, L.L.P.
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