Device for Separating Stacked Sheets

1. Field of the Invention

This invention relates to a device for separating stacked sheets, and more particularly to a device for separating photosensitive sheet material accumulated in a stack.

2. Description of the Prior Art

In the manufacture of photosensitive sheet materials such as X-ray film, comparatively large sized photographic film and so forth, it is often required to separate stacked sheets. Particularly, in the process of cutting the sheet material and the process of cutting the corners thereof to round them, the stacked sheets are likely to stick to each other and prevent smooth separation thereof. Sheets of photosensitive sheet material bearing a photographic emulsion layer are particularly apt to stick together since the surface of the emulsion layer is likely to be tacky.

In order to separate the stacked sheets, it has been known in the art to use an air blow as disclosed in Japanese Pat. No. 27249/1969. In this patent, a number of air blowing ports are provided on three sides of a stack of sheets on a sheet holder which is vibrated in the horizontal direction, and an air blow is applied to the edge of the stacked sheets to separate the sheets. This method of separating the sheets is disadvantageous in that the force acting to separate the sheets is weak since the cross sectional area of the air blowing ports is large, and a number of ports must be provided accordingly. Further, since the sheets are horizontally oriented and stacked vertically, the sheets in the uppermost part of the sheet stack are apt to be blown away by the air blow, and the sheets in the lower part of the sheet stack are far more difficult to separate than those in the upper part thereof. In addition, manual operation is required to align the sheets after separation.

It has also been known in the art to separate stacked sheets by a mechanical device as disclosed in Japanese Pat. No. 9061/1969. In this patent, it is disclosed to provide a movable member underneath a stack of sheets which are vertically oriented and accumulated in the horizontal direction so that some of the stacked sheets may be moved upward by the movable member as the member moves horizontally along the lower edge of the sheets. The movable member is screw-engaged with a screw rod extending perpendicular to the face of the sheets and moved along the lower side of the stack of the sheets by the revolution of the screw rod. This method of separating the stacked sheets is disadvantageous in that the lower edges of the sheets are apt to be scratched by the movable member since the movable member is moved in contact therewith. Further, this mechanical sheet separating device has a defect in that the speed of operation cannot be increased beyond a comparatively low speed.

In view of the above-mentioned observations and description of the conventional devices for separating stacked sheets, the primary object of the present invention is to provide a device for separating sheets accumulated in a stack wherein the sheets are effectively separated without manual operation.

Another object of the present invention is to provide a device for separating sheets accumulated in a stack in which the sheets are not scratched during the separating operation.

Still another object of the present invention is to provide a device for separating sheets accumulated in a stack which can be operated at a high speed.

A further object of the present invention is to provide a device for separating sheets accumulated in a stack wherein the sheets are automatically aligned with each other at the same time they are separated.

The above objects are accomplished by providing a rotary air blowing cylinder under a stack of sheets which are vertically oriented and accumulated in the horizontal direction. The rotary air blowing cylinder is rotatable about a shaft extending in parallel to the face of the sheets. The sheets are supported vertically and the stack of sheets is limited at its ends by a pair of end plates.

In accordance with the present invention, the sheets are separated at a high speed since the air blow applied from the lower side of the stack thereof is given by a rotary air blowing cylinder which imparts the air blow while swinging the direction thereof through an arc. Further, since the air blow is supplied by a rotary air blowing cylinder which is provided with a number of air nozzles arranged regularly at equal intervals over the face of the cylinder, the air blow is applied to the stack of sheets periodically at a predetermined frequency and consequently the sheets are vibrated in the sheet holder and automatically aligned with each other.

FIG. 1 is a perspective view schematically showing the essential structure of an embodiment of the present invention,

FIG. 2 is a cross sectional view of a rotary air blowing cylinder employed in the sheet separating device in accordance with the present invention,

FIG. 3 is a longitudinal view partially in section of the rotary air blowing cylinder as shown in FIG. 2,

FIG. 4 is a perspective view showing a preferred embodiment of the device in accordance with the present invention, and

FIG. 5 is a side elevational view of the preferred embodiment of the invention as shown in FIG. 4.

The essential structure of the device for separating sheets in accordance with the present invention is illustrated in FIG. 1. A sheet supporting holder 10 is constituted of a pair of end plates 11 and 12 which extend vertically in parallel to each other and a pair of support bars 13 and 14 extending between the end plates and fixed at opposite ends thereto. Under the sheet supporting holder 10 is located a rotary air blowing cylinder 20 rotatable about an axis 21 extending in parallel to said end plates 11 and 12.

The rotary air blowing cylinder 20 is provided with a number of air nozzles 23a on the cylindrical face thereof as shown in FIG. 1. The rotary air blowing cylinder 20 is illustrated in detail in FIGS. 2 and 3.

Referring to FIGS. 2 and 3, the rotary air blowing cylinder 20 is comprised of an inner cylinder 22 having a line of wide air outlets 22a arranged longitudinally thereon, and an outer cylinder 23 having a number of nozzles 23a rotatably mounted on the inner cylinder 22. The inner cylinder 22 is fixed to a stationary wall 30 and communicated with a compressed air supply (not shown). One end 22b of the inner cylinder 22 is closed as shown in FIG. 3. The closed end 22b is not necessary if the outer cylinder 23 which is rotatably mounted to the inner cylinder 22 is in air-tight engagement with the inner cylinder 22. The outer cylinder 23 is provided at an end thereof a driving shaft 24 which is connected with a driving means such as a motor (not shown). In the embodiment illustrated, the end of the outer cylinder 23 is closed as indicated at 23b. The inner cylinder 22 is provided with a flange 25 which is fixed to said stationary wall 30.

The air nozzles 23a provided on the outer cylinder 23 are arranged at equal intervals around the cylinder 23 and along the lengthwise direction of the cylinder 23 so that the air blow is periodically supplied to the stack of sheets.

As shown in FIG. 1, a stack of sheets S are vertically oriented and accumulated in the horizontal direction. The thickness of the stack of sheets S is smaller than the distance between the oppositely disposed end plates 11 and 12.

In operation of the above described device in accordance with the present invention, the rotary air blowing cylinder 20 is supplied with compressed air and the air is applied to the lower side of the stack of sheets S as an air blow from the air nozzles 23a. Since the inner cylinder 22 is fixed and the outer cylinder 23 is rotated thereon, the air blow is always directed upward through the wide air outlets 22a of the inner cylinder 22 and the air nozzles 23a of the outer cylinder 23 brought into alignment with the outlets 22a. Since the air nozzles 23a are arranged at equal intervals, the air blow is periodically applied to the stack of sheets S at a predetermined frequency. The periodical air blow or air pulses act to separate the sheets one by one until all sheets are separated in the sheet supporting holder 10. Since the air blow is periodically applied to the stack of sheets as air pulses, the sheets S are vibrated and caused to move horizontally in the direction to increase the thickness of the stack until the thickness becomes equal to the distance between the oppositely disposed end plates 11 and 12.

In the above embodiment, it should be noted that the direction of rotation of the outer cylinder 23 is not limited to that indicated by an arrow in FIGS. 1 and 3.

A preferred embodiment of the present invention is shown in FIGS. 4 and 5. In this embodiment of the invention, the sheets are effectively aligned simultaneously with the separation thereof. Referring to FIG. 4, seven vertical plates 41 are provided in parallel to each other. The vertical plates 41 correspond to said end plates 11 and 12 shown in FIG. 1. A side plate 42 having an L-shaped cross section is fixed to the upper end of the side of the vertical plates 41. A pair of support bars 43 and another pair of support bars 44 are fixed to the lower part of the vertical plates 41 and extend therebetween to support a stack of sheets S thereby. The vertical plates 41 fixed together by the support bars 43 and 44 are mounted on a base plate 45. On the base plate 45 is installed a motor 60 provided with a driving gear 62 mechanically connected therewith by way of a reduction gear in a gear box 61. A gear train comprising six spur gears 63 is meshed with the driving gear 62. Each gear 63 of the gear train is rotatably mounted on a side plate 46 fixed to the base plate 45 and is fixed to a driving shaft (not shown) of a rotary air blowing cylinder 50. The rotary air blowing cylinder 50 is rotatably supported under the support bars 43 and 44 in quite the same way as in the structure shown in FIGS. 1 and 3. As illustrated in FIG. 4, an air blowing cylinder 50 is provided in every space between adjacent vertical plates 41. The base plate 45 is fixed to a support column 70 in an inclined position as shown in FIG. 5.

In the above described construction of the embodiment shown in FIGS. 4 and 5, the distances between adjacent vertical plates 41 are all the same and the gears 63 all ahve the same number of teeth so that all the rotary air blowing cylinders may be rotated at the same speed.

In operation of the above described preferred embodiment of the invention, six stacks of sheets S are put into the six spaces between the seven vertical plates 41 and an air blow is applied on the lower side of the stacks by the air blowing cylinders 50. As the motor 60 rotates, the rotary air blowing cylinders 50 are rotated and air blow is periodically applied to the stacks of sheets as air pulses. Since the base plate 45 is inclined as shown in FIG. 5, the sheets S are automatically aligned after being separated by the air pulses. The side ends of the sheets are aligned on the end of the side plate 42 and the lower ends of the sheets are aligned on the support bars 43 and 44.

The following data were obtained by the inventors in experiments in which stacks of X-ray film were separated by a device in accordance with the above-described preferred embodiment of the invention. Since X-ray film is provided on both surfaces thereof with a photosensitive emulsion layer, it is particularly apt to stick together. In the experiments, several stacks of X-ray film which had become stuck together after being corner-cut were used as the sheets to be separated by the device. The speed of the rotary air blowing cylinders was 30, 60 and 90 r.p.m.

The diameter of the air nozzles 23a was 5mm. Three air nozzles were provided on a circle around the outer cylinder 23. The base plate 45 was inclined at 30.degree. to the horizontal plane. The air pressure of the compressed air source was 0.5Kg/cm.sup.2. The size of the sheets of X-ray film was 8 .times. 10 feet. A stack of 150 sheets of X-ray film was put into each space between adjacent vertical plates 41. The distance between the adjacent vertical plates 41 was about 50mm, which was about twice as large as the thickness of the stack of 150 sheets of X-ray film.

In accordance with the above experiments, the time for separating all the sheets was 5 seconds when the rotary air blowing cylinders were rotated at 15 r.p.m., 7 seconds when rotated at 30 r.p.m., 10 seconds when rotated at 60 r.p.m. and 12 seconds when rotated at 90 r.p.m. These results show that the speed of the air blowing cylinder is preferably 15 to 30 r.p.m.