JPH0899731A - Paper feed roller, manufacture of paper feed roller, sheet member feeding device, and image forming device - Google Patents

Abstract

PURPOSE: To extend the service life by relaxing the stress concentration at the pickup surface of a paper feed roller so as to prevent the damage of the paper feed roller, to prevent an erroneous pickup by stabilizing the abutting pressure between the paper feed roller and a sheet member to be fed, and to feed the sheet member stably and at a high reliability. CONSTITUTION: In a paper feed roller 1 which consists of an elastic member composed of a circular arc surface 2 abutting to a sheet member, and a flat surface 3 not abutting to the sheet member, in the external form, a pickup surface 4 as the end of the circular arc surface 2 abutting to the sheet member at first in the paper feeding operation is supported on a polyurethane sponge 6 (a material with a high elasticity).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding roller for feeding a sheet material as an original or an image recording medium used in a copying machine, a method for manufacturing the sheet feeding roller, and a sheet material provided with the sheet feeding roller. The present invention relates to a feeding device and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as a paper feed roller used in this type of copying machine, there is a D-cut type as shown in FIG.
The D-cut type paper feed roller 101 is a paper feed roller that conveys the sheet material by the frictional force between the paper feed roller and the sheet material when the arcuate surface 102 contacts the sheet material when the sheet material is fed. When the flat surface 103 faces the sheet material, the sheet material and the sheet feeding roller are separated from each other, and thus a dedicated retracting unit for retracting the sheet feeding roller from the sheet material is not required. Therefore, it is used in many copying machines because of its low cost and simple structure.

FIG. 7 shows a lower separation type sheet material feeding device for feeding the stacked sheet materials in order from the lowermost sheet material as an example of adopting the D-cut type sheet feeding roller 101.

Reference numeral 101 denotes a D-cut type paper feed roller, which is used as a pickup roller for picking up the sheet material S ′ stored and stacked on the tray 110 and conveying it to the retard roller pair 111.

Next, a conventional D-cut type paper feed roller 101
The paper feeding operation flow is shown in FIGS.

During the paper feed standby, the flat surface 103 of the paper feed roller 101 faces the sheet material S ', and the paper feed roller 101 and the sheet material S'are in a stand-by state (FIG. 8). Next, at the same time as the feeding is started, the feeding roller 101 rotates in the direction of arrow A101 in the figure, and the joining portion 104 of the flat surface 103 and the arcuate surface 102 (hereinafter referred to as the pickup surface 104) first comes into contact with the sheet material S '. The stationary sheet material S ′ is picked up (FIG. 9), and the sheet material S ′ picked up thereafter is the arc surface 102 and the sheet material S ′.
While being gripped by the frictional force generated on the contact surface of the sheet, the sheet is conveyed inside the copying machine (FIG. 10).

[0007]

However, the following problems have occurred in such a conventional example.

Since the D-cut type paper feed roller 101 picks up a sheet material which is stationary while the paper feed roller 101 itself rotates as described above, the pickup surface 104 is considerably formed in the state shown in FIG. It receives a shock and is greatly deformed locally. Therefore, usually arc surface 1
Although 02 is made of rubber having high wear resistance, even when almost all of the arcuate surface 102 has a surface layer close to that of a new article, only the pickup surface 104 is partially deteriorated due to impact and local deformation. This leads to defective pickup of the sheet material.

In other words, since the pickup surface is a very narrow area, stress concentration during pickup is large,
Unless this stress concentration is alleviated, it cannot be a fundamental measure against this problem.

Further, the pickup surface 104 shown in FIG.
The contact pressure generated when the sheet material S ′ and the sheet material S ′ contact each other is difficult to control because the pickup surface 104 impacts with the sheet material S ′, and a prescribed number, usually one sheet material S There is also a problem that many sheets are fed without picking up 'and a pickup error occurs.

The present invention has been made to solve the above-mentioned problems of the prior art. The purpose of the present invention is to relieve stress concentration on the pickup surface to prevent damage to the paper feed roller and extend the life. An object of the present invention is to provide a sheet feeding roller that stabilizes the contact pressure between the sheet feeding roller and the sheet material to be fed to prevent pick-up mistakes and is highly reliable and capable of stably feeding the sheet material. Also disclosed is a manufacturing method for making the paper feed roller in an effective manner.

[0012]

In order to achieve the above object, according to the present invention, an elastic member whose outer shape is composed of an arcuate surface that abuts a sheet material and a flat surface that does not abut the sheet material is provided. In this paper feeding roller, the end portion of the arc surface that first comes into contact with the sheet material during the paper feeding operation is supported by a member having a higher elastic force than other portions.

It is also effective that the outer peripheral surface layer of the paper feed roller is made of wear-resistant rubber, and a member having a high elastic force for supporting the end of the arc surface is made of foam.

Further, the member having a high elastic force may be a polyurethane sponge having an Asker F hardness of 50 ° to 80 °.

Further, the sheet material feeding device is provided with the above-mentioned sheet feeding roller and a sheet material accommodation means for accommodating the sheet material fed by the sheet feeding roller, and the sheet material feeding device and the sheet fed out. It is also preferable to equip the image forming apparatus with an image forming unit that forms an image on a material.

As a method of manufacturing the paper feed roller, the material of the outer peripheral surface layer and the material used for the member having a high elastic force are simultaneously extruded by an extrusion molding method to foam the material used for the member having a high elastic force. Mold.

[0017]

In the present invention constructed as described above, the impact contact pressure between the end of the arc surface (pickup surface) and the sheet material is eliminated, and the contact area is increased, so that the sheet Stress concentration during material pick-up is reduced.

Further, by using a foam member as the member having a high elastic force, it becomes possible to evenly support the ends of the arc surface.

Further, if the member having high elasticity is a polyurethane sponge having an Asker F hardness of 50 ° to 80 °,
The elastic coefficient at the end of the arc surface (pickup surface) is set to a desired value.

Further, by casting two different materials at the same time by the extrusion molding method, the outer peripheral surface layer and the inner portion having high elastic force are simultaneously formed, and the inner portion having high elastic force is foamed. The paper feed roller is manufactured.

[0021]

【Example】

(First Embodiment) FIG. 1 shows a D-cut type paper feed roller 1 of the present invention. The paper feed roller 1 is used, for example, in an image forming apparatus 11 as shown in FIG. 3, and feeds a sheet material.
In FIG. 3, reference numeral 10 is an image information reading unit that reads image information by optically scanning a document, and 20 is an image forming unit that forms the read image information on the sheet material S. 1a, 1
b is the paper feed roller of the present invention, and 21a and 21b are sheet materials S
A cassette on which the sheet is placed, 22 is a conveying path for the sheet material S, and 23
Is a pair of registration rollers for correcting skew of the sheet material S, 24
Is a photosensitive drum. The paper feed roller 1a or 1b appropriately selected by a signal from an image formation control unit (not shown) is
The sheet material S placed on the cassette 21a or 21b is picked up by rotating clockwise in FIG. After that, the sheet material S is sent to a registration roller pair 23 via a carrying roller (not shown) and a carrying path 22. The skew of the sheet material S is corrected by the pair of registration rollers 23, and the sheet material S is conveyed to the photosensitive drum 24 at the image forming timing.
After the image is transferred, it is separated from the photoconductor drum 24 by the separation claw 25, and is discharged to the discharge tray 29 via the fixing roller pair 27 and the discharge roller pair 28 by the conveying belt 26.

Returning to FIG. 1, the portion 5 of the paper feed roller 1 includes an outer peripheral surface layer made of wear-resistant rubber as an elastic member and has a high elastic force. It is a roller member that constitutes a roller portion of the roller 1. The polyurethane sponge is constructed integrally with the roller member 5, and is processed and manufactured by so-called two-color molding. Reference numeral 7 denotes a rotation shaft of the paper feed roller 1.

The polyurethane sponge 6 is a connecting portion between the circular arc surface 2 and the flat surface 3 of the paper feed roller 1, and is provided in the vicinity of the pickup surface 4 as the end of the circular arc surface 2 that first comes into contact with the sheet material during the paper feeding operation. Has been.

FIG. 2 shows a D-cut type paper feed roller 1 according to the present invention.
The state at the time of picking up the sheet material S when using is shown.

In this embodiment, since the pickup surface 4 has the urethane sponge 6 inside the roller member 5 made of abrasion resistant rubber, the pickup surface 4 has higher elasticity than the conventional example. Therefore, as shown in FIG. 2, when the sheet feeding roller 1 is rotated in the direction of arrow A1 and the pickup surface 4 and the sheet material S come into contact with each other, the pickup surface 4 bends from the broken line state to the solid line state in FIG. The contact area of the sheet material S increases.

For this reason, the stress concentration due to the impact and local deformation of the pickup surface 4, which is a problem in the conventional example, is relieved dramatically by the bending of the pickup surface 4, and the damage of the sheet feeding roller 1 is prevented.

Further, since the pickup surface 4 bends and comes into contact with the sheet material S, the impact pressure in the prior art is eliminated, and the sheet material S comes into contact with the sheet material S at a stable pressure.

Further, since the frictional force between the rubber and the sheet material is generally in a proportional relationship with the contact area between them, the sheet material conveying force on the pickup surface 4 can be improved.

It is desirable that the urethane sponge in this embodiment has an Asker F hardness of about 50 to 80 °, and if the hardness is higher than this hardness in the experimental value, the nip width of the pickup surface 4 cannot be secured and the sheet material is slanted or impacted. It is locally worn. On the other hand, if the sheet material is too soft, slipping occurs and the sheet material cannot be conveyed reliably.

However, the sponge hardness is not limited by the sponge hardness depending on the hardness of the wear resistant rubber and the outer shape and size of the D-cut sheet feeding roller, and it is possible to select the sponge hardness suitable for each condition. is there.

Further, the sponge material is not limited to polyurethane, and sponges made of other resin materials can be used without any problem. Further, the D-cut type paper feed roller in this embodiment has a knurl for removing paper dust on the arc surface 2, but the same effect as in this embodiment can be obtained even if the arc surface is a polished surface or a textured surface. It goes without saying that it will be done.

In the present embodiment, the arcuate surface 2 of the paper feed roller 1 is made of wear-resistant rubber as the elastic member, but the material is not limited and silicone rubber or plastic resin material may be used. Good. (Second Embodiment) FIGS. 4 and 5 show a second embodiment of the present invention. The paper feed roller 31 in this embodiment is composed of a roller member 35 made of one material, and the roller member 35 has a shape in which an arc surface 32 and a flat surface 33 are continuous. Three
Reference numeral 6 denotes a concave groove provided in the flat surface 33 that acts to increase the elastic coefficient of the pickup surface 34. Reference numeral 37 denotes a rotation shaft of the paper feed roller 31.

FIG. 5 shows a state in which the sheet material S is picked up when the sheet feeding roller 31 of the second embodiment is used.

In this embodiment, the pick-up surface 34 has a groove 36 formed in the flat surface 33 of the roller member 35 to increase the elastic coefficient of the pick-up surface 34, and the feed roller 31 is rotated in the direction of arrow A2. Then, when the pickup surface 34 and the sheet material S contact each other, the pickup surface 34 bends from the broken line state to the solid line state in the drawing.

Further, instead of the groove 36, it is possible to provide a hollow portion inside the pickup surface 34. (Third Embodiment) The sheet feeding rollers described in the first and second embodiments are applicable to various kinds of sheet material feeding devices, and as a known sheet material accommodating means, the cassette shown in FIG. Two
Like the sheet material feeding device that comes into contact with the upper surface side of the sheet material S housed in 1a and 21b to feed the sheet material or the sheet material feeding device in the related art of FIG. It is also possible to apply to the lower separation type sheet material feeding device that feeds the sheet materials in order.

When a document or recording material as a sheet material of an image forming apparatus such as a copying machine or a printer is conveyed,
Especially, it becomes indispensable to separate and send out one by one,
The present invention also includes the sheet feeding roller of the present invention and the above-described sheet material feeding device, stably feeding the sheet material, and thereafter performing image reading and image formation. (Fourth Embodiment) As a method of manufacturing a paper feed roller, two different materials are simultaneously cast by the extrusion molding method (so-called 2
By performing color molding, the outer peripheral surface layer and the inner portion having a high elastic force are formed at the same time, and the inner portion having a high elastic force is foamed to manufacture the paper feed roller.

The foaming may be carried out in the mold with a relatively slow extrusion speed, or the outer peripheral surface layer may be extruded at a speed capable of retaining the shape so that the foaming is finished after the mold is ejected. It is also possible to carry out by various processes.

[0038]

According to the present invention having the above-described structure and operation, the contact pressure between the sheet feeding roller and the sheet material to be fed is stabilized to prevent pick-up mistakes, and the sheet material is first Partial deterioration of the ends of the abutting arc surfaces can be suppressed, and the durability of the paper feed roller is improved. Therefore, it is possible to stably feed the sheet material.

Further, by adopting the sheet feeding roller of the present invention in a sheet material feeding device or an image forming apparatus, an apparatus in which the sheet material is stably fed can be provided.

Further, by forming the paper feed roller by the method described in the fourth embodiment, it is integrally formed, and the work such as adhesion and fitting of the two members is unnecessary and the cost is extremely low. A paper feed roller with high durability is created.

[Brief description of drawings]

FIG. 1 is a diagram of a sheet feeding roller to which the present invention is applied.

FIG. 2 is an explanatory diagram of a sheet feeding operation of a sheet feeding roller.

FIG. 3 is an image forming apparatus to which the paper feed roller of the present invention is applied.

FIG. 4 is a diagram of a second embodiment of the paper feed roller.

FIG. 5 is an explanatory diagram of a sheet feeding operation of a sheet feeding roller according to the second embodiment.

FIG. 6 is a diagram of a conventional paper feed roller.

FIG. 7 is a diagram of a sheet material feeding mechanism using a conventional paper feeding roller.

FIG. 8 is an explanatory diagram of a conventional paper feed roller during a paper feed standby.

FIG. 9 is an explanatory diagram of a paper feeding operation of a conventional paper feeding roller. .

FIG. 10 is an explanatory view of a conventional paper feeding roller during a carrying operation. .

[Explanation of symbols]

 1 Paper feeding roller 2 Arc surface 3 Flat surface 4 Pickup surface 5 Roller member 6 Polyurethane sponge (member with high elasticity)

Claims (6)

[Claims] 1. A sheet feeding roller made of an elastic member having an outer shape of an arcuate surface that abuts on a sheet material and a flat surface that does not abut the sheet material. A sheet feeding roller, wherein an end portion of the sheet is supported by a member having a higher elastic force than other portions. 2. The outer peripheral surface layer of the paper feed roller is made of wear resistant rubber, and a member having a high elastic force for supporting the end of the arc surface is made of foam. Paper feed roller described. 3. The paper feed roller according to claim 1, wherein the member having high elasticity is a polyurethane sponge having an Asker F hardness of 50 ° to 80 °. 4. The sheet feeding roller according to claim 1, and a sheet material accommodating means for accommodating a sheet material fed by the sheet feeding roller. Sheet material feeding device. 5. The sheet material feeding device according to claim 4,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet material fed by the sheet material feeding device. 6. A material for an outer peripheral surface layer and a material used for a member having a high elastic force are simultaneously extruded by an extrusion molding method to foam and mold a material used for a member having a high elastic force. 2. The method for manufacturing a paper feed roller described in 2 or 3.