EP0813935A1

EP0813935A1 - Paper cutting device

Info

Publication number: EP0813935A1
Application number: EP97110240A
Authority: EP
Inventors: Kirikoshi Takeharu; Hattori Kouichi
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1996-06-21
Filing date: 1997-06-23
Publication date: 1997-12-29
Anticipated expiration: 2017-06-23
Also published as: JPH106279A; CN1118368C; EP0813935B1; CN1172009A; DE69715101D1; DE69715101T2

Abstract

Disclosed is a paper cutting device, having: a stationary cutter (1) which has such a length as to cut a paper to be cut and includes a base portion where the paper is laid down, the stationary cutter being made of cold-rolled steel; a guide rail (1b) which is disposed in the direction of crossing the paper; a frame (1(a)) for composing linkage between the stationary cutter and the guide rail; a cutter holder (2) which reciprocatively moves through the guide rail (1b) and is so formed as to stride the stationary cutter (1), the cutter holder (2) including a cutting wheel (3) on the side of setting the paper on the stationary cutter (1) and having an aperture in its forward direction to expose an edge of the cutting wheel (3), the cutting wheel (3) being rotatably journaled by the cutter holder (2) so that the edge of the cutting wheel (3) intersects to an edge of the stationary cutter (1) at a predetermined quantity; means for pressing the edge of the cutting wheel (3) against the edge of the stationary cutter (1); and
carrying means for reciprocating the cutter holder (2).

Description

This invention relates to a paper cutting device which is provided in a facsimile machine, copier, printer or the like, and more particularly to, a paper cutting device which is provide with an elongate stationary cutter and a movable wheel cutter for cutting a roll of paper into sheets with a predetermined length.
Paper cutting devices provided in a facsimile machine, copier, printer or the like are used to cut a roll of paper into sheets with a predetermined length.
Japanese patent application laid-open No.7-124892(1995) discloses a typical example of a paper cutting device, where a cheaper stationary cutter which does not need any thermal treatment and edge-forming process is used and a wheel for rotating a cutting wheel can be removed by disposing the cutting wheel at a proper position.
In the conventional paper cutting device, the stationary cutter is of stainless steel which is treated by hardening. Though this material is much cheaper than tool steel generally used for cutters, it is still costly. Also, such a stationary cutter of steel needs to be stamped at a die-to-die clearance gap of zero. Therefore, the dies are quickly worn out and the quality control of the stationary cutter to be produced becomes severe.
On the other hand, in the conventional paper cutting device, the stationary cutter and the cutter frame are prepared individually and are fixed by spot welding. It causes an increase in cost. Though another example where a cutter frame and a stationary cutter are integrally formed has been suggested, it is not a practical product since its strength is weakened and the rail portion needs to be punched. Furthermore, it is difficult to work the material into a complex form since it is of stainless steel.
Furthermore, in the conventional paper cutting device, the cutting wheel is not easy to change since the cutter holder is screwed to the carriage.
Accordingly, it is an object of the invention to provide a paper cutting device where a stationary cutter, a cutter frame and a guide rail are integrally formed while obtaining a sufficient strength.
It is a further object of the invention to provide a paper cutting device which has a reduced manufacturing cost.
It is a still further object to provide a paper cutting device which has a high sheet-cutting performance.
According to the invention, a paper cutting device, comprises:

a stationary cutter which has such a length as to cut a paper to be cut and includes a base portion where the paper is laid down, the stationary cutter being made of cold-rolled steel;
a guide rail which is disposed in the direction of crossing the paper;
a frame for composing linkage between the stationary cutter and the guide rail;
a cutter holder which reciprocatively moves through the guide rail and is so formed as to stride the stationary cutter, the cutter holder including a cutting wheel on the side of setting the paper on the stationary cutter and having an aperture in its forward direction to expose an edge of the cutting wheel, the cutting wheel being rotatably journaled by the cutter holder so that the edge of the cutting wheel intersects to an edge of the stationary cutter at a predetermined quantity;
means for pressing the edge of the cutting wheel against the edge of the stationary cutter; and
carrying means for reciprocating the cutter holder.

The invention will be explained in more detail in conjunction with the appended drawings, wherein:

FIG.1 is a perspective view showing the conventional paper cutting device disclosed in Japanese patent application No.7-124892,
FIGS.2A to 2C are illustrations for explaining the arrangement of a cutting wheel and a stationary cutter in FIG.1,
FIG.3 is a perspective view shoving a paper cutting device in a first preferred embodiment according to the invention,
FIG.4 is a plan view of the paper cutting device in FIG.3 including a bottom view, top view and side views thereof,
FIG.5 is a broken perspective view of the paper cutting device in FIG.3,
FIG.6 is a cross sectional view cut along the line a-a in FIG.4,
FIGS.7A to 7C are illustrations explaining the arrangement of a cutting wheel and a stationary cutter in FIG.3,
FIG.8 is an illustration for explaining a state before when a cutting operation starts,
FIG.9 is an illustration for explaining a state at the time when the cutting operation starts,
FIG.10 is an illustration for explaining a state when the cutting operation is conducted,
FIG.11 is an illustration for explaining a state at the time when the cutting of paper is completed,
FIG.12 is a partial perspective view showing a paper cutting device in a second preferred embodiment according to the invention, and
FIG.13 is a partial perspective view showing a paper cutting device in a third preferred embodiment according to the invention.

Before explaining paper cutting devices in the preferred embodiments, the aforementioned conventional paper cutting device will be explained in FIGS.1 to 2C.
As shown in FIG.1, in the conventional paper cutting device, a linear elongate stationary cutter 20 is fixed welded on the upper surface of a cutter frame 21 to be parallel with a guide rail 22 provided on the cutter frame 21. The guide rail 22 is formed by bending one end of the cutter frame 21. Part of a carriage 23 is engaged with the guide rail 22. A cutter holder 25 has such a shape as the stationary cutter 20 can be held in the cutter holder 25 and is screwed to the carriage 23 at one end thereof. The cutter holder 25 slidably reciprocates along the guide rail 22. A drive mechanism with a wire 30 controls the movement of the cutter holder 25. The rotation shaft of a pulley 31 functions as a stopper to the cutter holder 25. The cutter holder 25 includes a front plow 27 for leading a sheet to the cutting point with the movement of the cutter holder 25 and a sheet guide 28 formed following the front plow 27. The sheet guide 28 guides the cutoff piece to a proper direction. The stationary cutter 20 has an edge with a slight curvature. The curvature is uniformly formed by stamping. The stationary cutter 20 is of stainless steel which is treated by hardening.
The arrangement of the cutting wheel 26 and the stationary cutter 20 will be detailed in FIGS.2A to 2C. The cutting wheel 26 is fitted to a bearing 32 and can be integrally rotated with it. A pin 33 of the cutting wheel 26 is inclined a predetermined angle of θz ° to the stationary cutter 20. Also, the pin 33 is disposed so that the edge of the cutting wheel 26 slightly overlaps the edge of the stationary cutter 20. Thereby, the edge of the cutting wheel 26 can contact the edge of the stationary cutter 20 at one contact point. The contact point is the sheet-cutting point where a sheet is cut off. The cutting wheel 26 is pressed against the edge of the stationary cutter 20 at a predetermined load(Fs) by a pressing means such as a leaf spring. When the cutting wheel 26 is moved in the sheet-cutting direction, the cutting wheel 26 is rotated at a constant cycle by moment(M) generated at the contact point. To obtain the moment required, some conditions need to be optimized.
Next, a paper cutting device in the first preferred embodiment will be explained below.
As shown in FIGS. 3 and 4, the paper cutting device in the first embodiment comprises a stationary cutter 1 elongated in the direction of crossing a paper to be supplied, a cutter holder 2 which has such a shape as strides the edge of the stationary cutter 1 and is movably supported by the stationary cutter 1, a cutting wheel(rotating cutter) 3 rotatably supported by the cutter holder 2, and a carrying means for carrying the cutter holder 2. In the this embodiment, the carrying means employs a drive mechanism including a wire 6. Alternatively, the carrying means may employ another known drive mechanism. For example, the carrying means may be a user's hand.
The stationary cutter 1, a frame 1a and a guide rail 1b for guiding the movement of the cutter holder 2 are integrally formed of single steel plate. The number of parts is decreased by integrally forming the stationary cutter 1 and the other parts by using the signal steel plate. The stationary cutter 1 also serves as a base portion 1c for setting a paper thereon. When the paper cutting device is used in a device where a paper is carried through, e.g., a facsimile machine, the stationary cutter 1 also serves as a paper-carrying base. The material of the stationary cutter 1 is a cold-rolled steel plate. Therefore, the stationary cutter 1 is very cheap and it is very easy to work whereby the quality of product is stabilized. The stationary cutter 1 can be used without conducting an edge-forming process to a steel plate stamped by press dies. In this case, no die-to-die clearance gap is given to a place where the dies stamp the edge. If such a stamping process is applied to a material with a high hardness, the dies must be quickly worn out. However, when the cold-rolled steel plate is used, the life of the dies can be much extended.
The cutter holder 2 can be reciprocated on the guide rail 1b, and it has such a shape as strides the edge of the stationary cutter 1, and it stores the cutting wheel 3 on the paper setting side of the stationary cutter 1 and is opened in the forward direction so that the edge of the cutting wheel 3 is exposed. Divided by the stationary cutter 1, it has a cutting wheel holder portion 2a on the paper setting side of the stationary cutter 1 and a carriage 2d on the back side of the stationary cutter 1. The carriage 2d is formed integrally with a slidable support 2o. The cutting wheel holder portion 2a and the carriage 2d are linked to each other by a link arm 2k striding the edge of the stationary cutter 1. The cutting wheel holder portion 2a is preferably detachable. In this embodiment, the cutting wheel holder portion 2a comprises a cutting wheel holder's support member 2b and a cutting wheel holder 2c. The cutting wheel holder 2c is fixed to the cutting wheel holder's support member 2b by a locking hook 2n. The cutting wheel holder 2c is also detachable and needs no tool to be released.
The cutting operation is conducted by forwarding the cutter holder 2 from the rear side to the front side in the longitudinal direction of the frame 1a. After completing the cutting operation, the cutter holder 2 is returned from the front side to a waiting position on the rear side and stands by for the next cutting operation. The cutting wheel holder portion 2a has a front guide portion 2g and a sheet guide portion 2h following the front guide portion 2g at its front part in the forward direction. The front guide portion 2g is formed as an oblique surface which can put down the paper floating up from the stationary cutter 1 when the cutter holder 2 is forwarded. The sheet guide portion 2h is formed as a horizontal surface which faces parallel to the stationary cutter 1, whereby a narrow gap is formed between the sheet guide portion 2h and the stationary cutter 1. The paper to be supplied is guided through the narrow gap to a sheet-cutting point which is a contact point between the cutting wheel 3 and the stationary cutter 1. Furthermore, the sheet guide portion 2h is followed by a rear guide portion 2i which guides the end of the cut-off sheet to a predetermined direction. The rear guide portion 2i is formed as a surface which is gently sloped from the sheet guide portion 2h to the carriage 2d while scraping the link arm 2k so that it strides over the paper. If the slope is steeply formed, the link arm 2k may affect the paper. Therefore, the slope needs to be gentle. In this embodiment, by using these components, the paper can be cut off while absorbing the flapping of the paper and the cut-off sheet can be guided to the predetermined direction. Therefore, the cutting operation can be conducted without using a paper carrying guide to define a narrow gap over the stationary cutter 1. Also, there is no problem that the cut-off sheet is jammed interfered by the link arm 2k. The cut-off sheet drops in the direction of the carriage 2d. The cut-off sheet may contact the cutter holder 2 when the cutter holder 2 is moved back and forth. If the cutter holder 2 contacts and kicks away the cut-off sheet, jamming happens. Therefore, the cutter holder 2 needs to be provided with means for preventing the kicking-away. Thus, the carriage 2d of the cutter holder 2 is provided with a front plow portion 2p at its end in the forward direction which is formed as an oblique surface which is inclined so that the cut-off sheet can be pushed away and a rear plow portion 2m at the other end in the backward direction which is formed as an oblique surface which is inclined so that the cut-off sheet can be pushed away. Meanwhile, the entire carrying means is disposed on the side of the carriage 2d. Namely, over the stationary cutter 1, there is no parts that may obstruct the setting of the paper. Thus, the paper can be easily set.
As shown in FIG.5, the carrying means employs the drive mechanism including the wire 6. To both ends of the wire 6, stop members 6b, 6b are fixed. Adjacent to one end of the wire 6, a coil spring 6a is attached. The coil spring 6a applies tension to the wire 6. The ends of the wire 6 are engaged with the carriage 2d of the cutter holder 2. There are fixed a drive pulley shaft 7a on the rear side in the longitudinal direction of the stationary cutter 1 and a middle pulley shaft 12a on the front side in the longitudinal direction of the stationary cutter 1. A drive pulley 7 is fitted to the pulley shaft 7a and a middle pulley 12 is fitted to the pulley shaft 12a. The drive pulley 7 is formed integrally with a drive gear 7b. A motor 8 is disposed on the side of the drive pulley 7. A pinion gear 8a is fitted with the rotation shaft of the motor 8, whereby the rotation of the motor 8 is transmitted to drive pulley 7. The motor 8 is fixed to the frame 1a by a screw 9. Lock washers 13, 13 are fitted to the drive pulley shaft 7a and the middle pulley shaft 12a, respectively, to prevent the release of the pulleys.
As shown in FIGS.5 and 6, the cutting wheel 3, a bearing 3a, a wheel 3b and a flange 3c are integrally assembled. The cutting wheel 3 is rotatably supported by a cutting wheel shaft 10. Also, the cutting wheel 3 is pressed against the edge of the stationary cutter 1 by a leaf spring 11. The cutting wheel 3 has a sharp edge at its circumference. The cutting wheel shaft 10 is disposed so that the wheel 3b is pressed against the stationary cutter 1. Pressed against the stationary cutter 1, there occurs a predetermined amount of deformation in the wheel 3b. Thereby, the cutting wheel 3 rotates when the cutter holder 2 moves. The wheel 3b and the carriage 2d of the cutter holder 2 are sandwiching the stationary cutter 1 therebetween by utilizing a stress due to the deformation of the wheel 3b. The cutting wheel shaft 10 is supported by the cutting wheel holder 2c and a lid 5. The lid 5 is fixed integrally with the cutting wheel holder 2c.
Next, the arrangement of the cutting wheel 3 and the stationary cutter 1 will be detailed below. As shown in FIGS.7A to 7C, the cutting wheel 3 and the stationary cutter 1 are crossed more than a predetermined amount. The cutting wheel 3 is pressed against the stationary cutter 1 by the leaf spring 11. The cutting wheel 3 rotates at a constant cycle in the direction reverse to the forward direction of the cutter holder 2. The cutting wheel 3 is disposed at an angle of 0.5° to 3°, preferably at an angle of around 2°, to the cutting plane so that the cutting wheel 3 contacts the stationary cutter 1 only at one point that relates to the cutting operation, i.e., the point of intersection in the forward direction of the cutter holder 2, of two points of intersection generated by the intersection between the edges of the cutting wheel 3 and the stationary cutter 1. Thereby, the edge of the cutting wheel 3 surely contacts the edge of the stationary cutter 1. Therefore, the stability in cutting performance can be much enhanced.
If the angle is less than 0.5°, a position other than the edge of the cutting wheel 3 will contact the stationary cutter 1. It causes a failure in the cutting operation. On the other hand, if the angle is more than 3°, the cutting wheel 3 will excessively contact the stationary cutter 1. Thus, the cutting function will be lost.
The wheel 3b is also disposed inclined since the wheel 3b and the cutting wheel 3 are integrally assembled. The wheel 3b draws the paper to the edge of the cutting wheel 3 while rotating as well as pressing the paper onto the stationary cutter 1. It further stabilizes the cutting operation. The cutting wheel 3 is pressed against the stationary cutter 1 at a pressure of 150g to 350g, preferably 250g. If the pressure is lower than 150g, the edge of the cutting wheel 3 will be lifted up from the edge of the stationary cutter 1 especially in case of a thick paper. Thus, it causes a failure in the cutting operation. On the other hand, if the pressure is higher than 350, the cutting wheel 3 will excessively contact the stationary cutter 1 or run on the stationary cutter 1. Thus, the cutting function will be lost.
The diameter of the cutting wheel shaft 10 is set to be 2 mm or less, preferably around 1 mm. If the diameter is more than 2 mm, the rotational load can prevail over the rotational power of the cutting wheel shaft 10. This causes a failure in the cutting operation since the rotation of the cutting wheel 3 becomes unstable.
The above numerical conditions are defined based on data proved from experiments, which are applicable to the case that the stationary cutter is of cold-rolled steel plate. The above numerical values defined as preferable ones are obtained by optimum conditions where SECC is used. The setting of the conditions depend on hardness of materials. When a material with hardness equal to that of SECC is used, such conditions as defined in the case of SECC can be applied thereto as well. It is proved in experiments that the paper cutting device which satisfies the optimum conditions can cut off a soft paper with high water absorbency such as a paper tissue even under the high-temperature and high-humidity condition of 35°C, 85%.
Next, the cutting operation of the paper cutting device in the first embodiment of the invention will be explained below. As shown in FIG.8, the waiting position of the cutter holder 2 is located at the rear end in the longitudinal direction of the stationary cutter 1. At the waiting position, the cutter holder 2 stops abutting the drive pulley 7. When the motor 8 rotates counterclockwise, the rotation power of the motor 8 is transmitted through the pinion gear 8a to the drive pulley 7, and the wire 6 pulls the cutter holder 2 toward the front end in the longitudinal direction of the stationary cutter 1. The cutting wheel 3 rotates at a constant cycle with the movement of the cutter holder 2. At this time, the cutting wheel 3 rotates in the direction reverse to the forward direction of the cutter holder 2. If the paper is floating over the stationary cutter 1 before the cutting starts, the front guide portion 2g serves to put down the paper. The paper is, as shown in FIG.9, guided through the sheet guide portion 2h to the cutting point. When the cutting starts, the cut-off sheet is, as shown in FIG.10, guided downward striding the stationary cutter 1 through the rear guide portion 2i. The cut-off sheet can be smoothly guided since the rear guide portion 2i is formed as a gently sloped surface. Then, as shown in FIG.11, the cut-off sheet drops to a place apart from the paper cutting device as if it is flown away from there. After completing the cutting operation, the cutter holder 2 abuts to the middle pulley 12 and stops its movement. The rotation of the motor 8 is controlled by a timer. Thereby, the motor 8 rotates counterclockwise for a predetermined time, and then it rotates clockwise for a predetermined time after the stopping. In this embodiment, the motor 8 rotates counterclockwise for one second to cut a paper 257 mm in width and then rotates clockwise for one second. When the cutter holder 2 returns to the waiting position and the motor 8 stops rotating, the cutting operation is completed. Such a control method of motor is disclosed in, for example, Japanese utility model application laid-open No.7-39580(1995). The control method of the motor 8 is not limited and can be altered by using known means.
With respect to the safety of the paper cutting device in the first embodiment, the cutting wheel 3 is stored inside the cutter holder 2 and the edge of the cutting wheel 3 is exposed in such a minimum degree as is required to cut off the paper. Therefore, it is not possible for users to touch the edge of the cutting wheel 3, excepting an intentional case. Furthermore, the edge of the stationary cutter 1 has a round shape as it is stamped and is not sharpened. Namely, even when the users touch the edge of the stationary cutter 1, their fingers are not injured.
In the second preferred embodiment of the invention, the cutter holder 2 may be, as shown in FIG.12, of an inseparable type, whereas, in the first embodiment, the cutting wheel holder 2c of the cutting wheel holder portion 2a is detachable from the cutting wheel holder's support member 2c.
In the third preferred embodiment of the invention, the frame 1a including the stationary cutter 1 may be, as shown in FIG.13, L-shaped, whereas, in the first embodiment, the frame 1a including the stationary cutter 1 is formed like a box.
Meanwhile, the composition or shape of the cutter holder 2, the shape of the guide rail 1b and the carrying means for carrying the cutter holder 2 are not limited to the above embodiments, and they can be altered by known technology.

Claims

A paper cutting device, comprising:
a stationary cutter which has such a length as to cut a paper to be cut and includes a base portion where said paper is laid down, said stationary cutter being made of cold-rolled steel;

a guide rail which is disposed in the direction of crossing said paper;

a frame for composing linkage between said stationary cutter and said guide rail;

a cutter holder which reciprocatively moves through said guide rail and is so formed as to stride said stationary cutter, said cutter holder including a cutting wheel on the side of setting said paper on said stationary cutter and having an aperture in its forward direction to expose an edge of said cutting wheel, said cutting wheel being rotatably journaled by said cutter holder so that the edge of said cutting wheel intersects to an edge of said stationary cutter at a predetermined quantity;

means for pressing said edge of said cutting wheel against said edge of said stationary cutter; and

carrying means for reciprocating said cutter holder.
A paper cutting device, according to claim 1, wherein:
said stationary cutter, said guide rail and said frame are integrally formed as a steel plate.
A paper cutting device, according to claim 1 or 2, wherein:
said cutting wheel is disposed at an angle of 0.5° to 3° to a cutting plane so that said cutting wheel contacts said stationary cutter only at one point of intersection in the forward direction of said cutter holder of two points of intersection generated by the intersection between said edges of said cutting wheel and said stationary cutter.
A device, according to claim 1, 2 or 3, wherein:
said pressing means has a pressure of 150 g to 350g.
A device, according to claim 1, 2, 3 or 4 further comprising:
a wheel which rotates integrally with said cutting wheel and contacts a plane of said stationary cutter where said paper is set.
A paper cutting device, according to claim 5, wherein:
said cutter holder and said wheel sandwich said stationary cutter.
A device, according to any of claims 1 to 6, wherein:
said stationary cutter is a stamped steel plate and has a rounded edge.
A device, according to any of claims 1 to 7, wherein:
said cutter holder comprises a cutting wheel holder for storing said cutting wheel, a carriage movable along said guide rail and an arm for linking said cutting wheel holder and said carriage while striding said stationary cutter; and

said cutter holder further comprises a front guide portion formed at the front end in the forward direction, a sheet guide portion following said front guide portion and a rear guide portion following said sheet guide portion, said rear guide portion being so formed as to scrape said arm.
A paper cutting device, according to claim 8, wherein:
said carriage of said cutter holder includes a front plow portion at a front end in the forward direction.
A paper cutting device, according to claim 8, wherein:
said carriage of said cutter holder includes a rear plow portion at a front end in the backward direction.
A device, according to any of claims 1 to 10, wherein:
said cutting wheel holder of said cutter holder is detachable.