JP2001302084A - Paper punching unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper punching unit capable of simply dispersing punching loads by plural punching shafts. SOLUTION: Plural eccentric cams 8a, 8b, 8c are mounted side by side to a driving shaft 4 rotated by a driving source such as a motor, and plural punching shafts 5a, 5b, 5c move up and down by being engaged with these plural eccentric cams 8a, 8b, 8c respectively. The driving shaft 4 is obliquely journaled so that an interval between the shaft and a paper guiding surface is inclined relative to the surface. The plural punch shafts 5a, 5b, 5c are held by holders 9a, 9b, 9c respectively, and the punch shafts moves up and down together with the holder by each eccentric cam engaged with each holder. Each holder has a box-shape enclosing respective eccentric cam, and also has an oblong guide hole 10 to pass the driving shaft 4 through.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet punching unit for punching a conveyed sheet with a plurality of punch shafts, and relates to a sheet post-processing apparatus for an image forming apparatus such as a printer or a copying machine. It is suitable.

[0002]

2. Description of the Related Art In a conventional paper punch unit, a plurality of eccentric cams for vertically moving a plurality of punch shafts are provided with a phase difference from each other in order to minimize the load caused by simultaneous driving of the plurality of punch shafts. It was attached to the drive shaft.

However, in such a paper punch unit, in order to make a phase difference between the eccentric cams, it is necessary to form a hole for mounting the eccentric cam with an angle difference between the shafts. And cost was high.

[0004] Further, in the other method of providing a phase difference, it is necessary to reverse the mounting direction of the eccentric cam so as to have a phase difference. In addition, with the method of changing the direction of the eccentric cam, it is not possible to make only two patterns of phase shift,
In the case of three holes or four holes, at least two or more punch shafts may be simultaneously punched, resulting in a problem that the effect of reducing the load is reduced.

Further, in the paper punch unit disclosed in Japanese Utility Model Laid-Open Publication No. 61-184698, a time difference of punching is provided by changing the length of the punch shaft. In addition, many types of punch shafts are required, and there is a problem that assembly and parts management become troublesome and cost increases.

On the other hand, in a paper punch unit that does not use a holder for holding a punch shaft, the punch shaft is pulled up by a spring attached to the punch shaft. Since it acts in a direction against movement of the shaft, a load for driving the punch shaft increases, and a large driving force is required. Further, since the spring is returned only by the force of the spring, the reliability is low, and in order to increase the reliability, the force of the spring needs to be increased. As a result, a large driving source is required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper punch unit capable of easily dispersing the load of punching by a plurality of punch shafts.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a sheet punching unit for punching a sheet conveyed from an image forming apparatus or the like with a plurality of punch shafts, the sheet being rotated by a driving source such as a motor. A plurality of eccentric cams are mounted side by side on a drive shaft, and a plurality of punch shafts move up and down by engaging with each of the plurality of eccentric cams, and the drive shaft moves with respect to a sheet guide surface for guiding a sheet. , Are obliquely supported so that the interval between them is inclined.

According to the second aspect of the present invention, in the above configuration, a plurality of punch shafts are respectively held by holders,
When each eccentric cam is engaged with each holder, the punch shaft is moved up and down together with the holder.

In the invention according to claim 3, each holder has a box-like shape surrounding each eccentric cam and has a guide elongated hole through which the drive shaft passes.

[0011]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a sheet punch unit according to the present invention as viewed obliquely from above, FIG. 2 is a perspective view as viewed obliquely from below, and FIG. 3 is a front view.

In the sheet punch unit 1, an upper guide plate 2 and a lower guide plate 3 for guiding a sheet are integrally fastened at a predetermined interval, and a sheet conveyed from an image forming apparatus (not shown). Are guided between the upper guide plate 2 and the lower guide plate 3.

Both end portions of the upper guide plate 2 are bearing side portions 2a and 2b on both sides supporting the drive shaft 4 by being bent upward at a right angle. The bearing side portions 2a and 2b have an oval shape. Bearing holes 2c and 2d are provided.
The flanged bearings 7a and 7b on both sides of the drive shaft 4 are press-fitted into 2d and fixed by retaining rings (not shown). Bearing 7
The a.7b cannot rotate with respect to the bearing holes 2c and 2d, but penetrates the drive shaft 4 and rotatably supports it.

The bearing holes 2c and 2d on both sides differ in height from the paper guide surface of the upper guide plate 2. For example, in FIG. 1, the height on the near side is Ha in FIG. 3, and if the Ha is 37 mm. 1, the height on the back side is Hb in FIG. 3, and the Hb is 35 mm, which is 2 m
m (Ha> Hb). Because of this difference,
The drive shaft 4 is obliquely supported so that the interval between the drive shaft 4 and the paper guide surface of the upper guide plate 2 is inclined.

On the upper guide plate 2, for example, three thrust bearings 6a, 6b, and 6c for guiding three punch shafts 5a, 5b, and 5c of the same length so as to slidably penetrate therethrough.
Are mounted at equal intervals on a straight line parallel to the axis of the drive shaft 4.

On the other hand, holes 3a, 3b and 3c are formed in the lower guide plate 3 at positions corresponding to the thrust bearings 6a, 6b and 6c, respectively, penetrating the upper guide plate 2. The punched holes 3a, 3b, 3c are
The diameter is slightly larger than 5b and 5c, and functions as a die.

The drive shaft 4 has three eccentric cams 8a and 8b.
8c is fixed by penetrating the drive shaft 4 so as to be at the same angle. For each eccentric cam 8a, 8b, 8c, a box-shaped holder 9a, 9b, 9c surrounding the eccentric cam 8a, 8b, 8c is mounted on the drive shaft 4. The punch shafts 5a, 5b, 5c project from the lower surfaces of the holders 9a, 9b, 9c, respectively.

Each of the holders 9a, 9b and 9c has a guide slot 10 through which the drive shaft 4 passes, and the corresponding eccentric cam 8a
8b and 8c are engaged with each other, so that they can be moved in the vertical direction by their rotation.

Next, the operation will be described. The conveyance of the sheet conveyed by a conveyance unit (not shown) of the image forming apparatus is stopped at a position where punching is performed. Thereafter, when a punch unit drive motor (not shown) rotates the drive shaft 4, the eccentric cams 8a, 8b and 8c rotate simultaneously. Eccentric cam 8a
The holders 9a, 9b, and 9c engaged with the cam surfaces are simultaneously pushed down by the rotation of 8b and 8c.

When the holders 9a, 9b and 9c are pushed down, the state of the sectional view of FIG. 4 is changed to the state of the sectional view of FIG. 5, and the punch shafts 5a, 5b and 5c are pushed down at the same time. The punch shafts 5a, 5b, 5c are inserted into the punched holes 3a, 3b, 3c, and holes are formed in the paper between the upper and lower guide plates 2, 3.

At this time, the drive shaft 4 is connected to the upper and lower guide plates 2.3.
The punch shafts 5a and 5b
5c has the same length but a different height, and is pierced sequentially with a time difference from the lower side (the far side in the example of the figure).

In this embodiment, the holding of the punch shaft,
Although the holder was used for lifting, the punch shaft was directly pressed by the cam without using the holder, and the punch shaft was lifted by using a spring for lifting, but by tilting the drive shaft, each punch was lifted. The same effect can be obtained in reducing the driving load by creating a time difference during the operation of the shaft.

[0023]

In the paper punch unit according to the present invention, since the drive shaft is obliquely mounted, a time lag can be created when a plurality of punch holes are made, and the punching by a plurality of punch shafts is performed. Load can be easily distributed.

In addition, since the time difference is created by making the drive shaft oblique, the punch shaft and its holder can be commonly used, and the cost and the parts management can be reduced. Furthermore, the direction of the parts can be unified in the assembly, the process management can be simplified, and an inexpensive assembly process can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a paper punch unit according to the present invention as viewed obliquely from above.

FIG. 2 is a perspective view of the same seen from obliquely below.

FIG. 3 is a front view of the same.

FIG. 4 is a sectional view of a normal state.

FIG. 5 is a sectional view of an operation state.

[Explanation of symbols]

 Paper punch unit 1 Upper guide plate 2 Bearing sides 2a, 2b Bearing holes 2c, 2d Lower guide plate 3 Drilled holes 3a, 3b, 3c Drive shaft 4 Punch shafts 5a, 5b, 5c Thrust bearings 6a, 6b, 6c Bearings 7a, 7b Eccentric cam 8a, 8b, 8c Holder 9a, 9b, 9c Guide slot 10

Claims (3)

[Claims] A plurality of eccentric cams arranged side by side on a drive shaft rotated by a drive source, wherein a plurality of eccentric cams are attached to a plurality of eccentric cams. The punch shaft engages with each of the plurality of eccentric cams and moves up and down, and the drive shaft is supported obliquely so that the interval between the drive shaft and the paper guide surface is inclined. A paper punch unit. 2. A plurality of punch shafts are respectively held by holders, and each eccentric cam engages with each holder,
The paper punch unit according to claim 1, wherein the punch shaft is moved up and down together with the holder. 3. Each holder is box-shaped surrounding each eccentric cam,
3. The sheet punch unit according to claim 2, wherein the sheet punch unit has a guide slot through which the drive shaft passes.