JP2000289879A - Carry roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily set and control a resist roller required for carrying paper with high accuracy by forming a carry roller contacting with a counter roller and rotating so as to have a shaft body and a rubber layer, making the rubber layer of urethane rubber composition, and setting the hardness in a specific range. SOLUTION: This carry roller is formed by having a shaft body 11 and a rubber layer 12, and the rubber layer 12 is formed out of urethane rubber composition. For this urethane rubber composition, for example the rubber containing ether series polyol, isocyanate, and glycol series crosslinking agent is mentioned. Further hardness of the rubber layer 12 is used to be in the agent of JIS A 60-90 Hs. In such rubber composition, the blending quantity of isocyanate is favorable to be set in the range of 30-60 pts.wt. against ether series polyol 100 pts.wt. For the glycol series cross linking agent, it is not limited in particular, but 1,4-butanediol or the like is mentioned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transport roller used in a paper feeding device such as a copying machine, a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art Paper feeders such as copiers, facsimile machines and printers have a mechanism as shown in FIG. 2, for example. In the illustrated apparatus, a pickup roller 3 is disposed in front of a paper tray 2 in which paper 1 is stored. The pickup roller 3 is a rubber roller that can feed the paper 1 in the paper tray 2. Reference numeral 4 denotes a paper feed roller, and reference numeral 5 denotes a retard roller, which are installed so as to be opposed to each other, and rotate while contacting each other. Both rollers 4 and 5 are also rubber rollers, but the retard roller 5 has a torque limiter 6 built therein.
This prevents two or more sheets of paper 1 from being sent together. Numeral 8 denotes a conveying roller, which is driven to convey the paper 1 and is installed in a state opposite to the mating roller 7 for applying a load, and comes into contact with each other and rotates. I have. At this time, the partner roller 7 is driven and rotated by the transport roller 8. Both rollers 7, 8
Is to sequentially feed the paper 1 fed by the paper feed roller 4 and the retard roller 5 to the developing unit, and a plurality of papers 1 may be provided depending on the distance to the developing unit. In addition,
As a countermeasure against skew (oblique feeding of the paper 1), generally, the leading edge of the paper 1 is aligned by a registration roller (not shown). The registration roller is stopped for a predetermined time when the paper 1 enters, so that a loop is formed in the paper 1 so that the leading ends of the paper 1 can be aligned. After the leading edge of the paper 1 is aligned, the registration roller is driven to convey the paper 1.

[0003] Conventionally, the conveying roller 8 of the paper feeder has a friction coefficient of a certain value or more on the outer peripheral surface of a shaft body.
In addition, a rubber layer having a rubber layer capable of maintaining the friction coefficient for a long time is used. And
As a material for forming this rubber layer, it has a good coefficient of friction,
Moreover, ethylene-propylene-diene copolymer (EPDM), chloroprene rubber (CR), and the like, which are excellent in weather resistance, are used.

[0004]

SUMMARY OF THE INVENTION However, EPD
When the conveying roller 8 using M or the like is used and the registration roller is not installed, the conveying force varies due to the contact state with the partner roller 7, the deterioration of the material due to the passing of the conveying roller 8 and the change of the surface state. This causes skew and a shortage of the transport amount, and the function cannot be satisfied. For this reason, registration rollers must be installed.
When the transport roller 8 using M or the like is used, the variation of the transport amount is large, the setting and control of the registration roller become very complicated, and when the transport amount is small, the function of the registration roller cannot be performed. Because it is possible,
It is very difficult to obtain inexpensive and stable performance, and it is not possible to meet demands for cost reduction and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide a transport roller capable of easily setting and controlling registration rollers required for highly accurate paper transport.

[0006]

In order to achieve the above object, a transport roller according to the present invention is a transport roller that rotates while being in contact with a mating roller, and includes a shaft and an outer periphery of the shaft. A rubber layer to be formed, wherein the rubber layer is made of a urethane rubber composition and has a hardness of JIS A60-9.
The configuration is such that it is set in the range of 0Hs.

The inventors of the present invention have made intensive studies to provide a transport roller that can easily set and control the registration roller and that can realize highly accurate paper transport without installing the registration roller. Stacked. In the process, the present inventors, when actually using the transport roller incorporated in a copying machine or the like, the actual value of the paper transport amount is the theoretical value of the paper transport amount determined by the rotation speed and outer diameter of the transport roller Therefore, attention was paid to the fact that the number of rotations and the driving time of the conveying roller 8 were set to be larger than the theoretical values. That is, no matter how good the friction coefficient is, the actually measured value of the paper transport amount is always lower than the theoretical value (especially when the force required to pull out the paper from the paper feeding unit is large, it is significantly lower). ), Recalling the introduction of a new index that does not depend on the friction coefficient that has been regarded as important. As a result, a slip ratio determined by subtracting the actual value of the paper transport amount from the theoretical value of the paper transport amount and dividing the result by the theoretical value of the paper transport amount is introduced [slip ratio (%) = ( Theoretical value-actual value) / theoretical value x 100]. Since the slip ratio is an index indicating that the smaller the value is, the better the paper transport amount is. Therefore, the present inventors have repeated experimental studies to determine conditions for reducing the slip ratio.
As a result, in the conveying roller rotating in contact with the mating roller, the rubber layer formed along the outer periphery of the shaft body is formed using the urethane rubber composition, and the hardness of the rubber layer is determined according to JIS A60- It was found that the slip rate was extremely small if the range was set to 90 Hs, and the intended purpose could be achieved.

[0008] In the present invention, the "counter roller"
For example, a resin roller, a metal roller, or the like can be used.

[0009]

Next, an embodiment of the present invention will be described.

[0010] The transport roller of the present invention rotates in contact with a mating roller, and includes a shaft and a rubber layer formed along the outer periphery of the shaft, and the rubber layer is formed of urethane rubber. It is made of a composition and its hardness is set in a specific range.

An example of the transport roller of the present invention will be described with reference to FIG. The transport roller includes a shaft 11 and a rubber layer 12 formed along the outer periphery of the shaft 11.

The shaft 11 is not particularly limited, and any conventionally known shaft may be used. For example, a metal core made of a solid metal body or a metal cylindrical body whose inside is hollowed out is used. Examples of the material include aluminum and stainless steel. Further, an adhesive, a primer, and the like can be applied on the shaft body 11 as needed. The adhesive, the primer and the like may be made conductive as needed.

The rubber layer 12 formed on the outer peripheral surface of the shaft 11 is formed using a urethane rubber composition. Examples of the urethane rubber composition include those containing an ether polyol, an isocyanate, and a glycol crosslinking agent.

The ether polyol is not particularly limited, and examples thereof include polypropylene glycol (PPG) and polytetramethylene ether glycol (PTMG). These may be used alone or in combination of two or more.

The isocyanate used together with the above-mentioned ether polyol is not particularly limited. For example, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,2 6-tolylene diisocyanate (2,6-TDI) and the like. These may be used alone or in combination of two or more.

The amount of the isocyanate is as follows:
The amount is preferably set in the range of 30 to 60 parts with respect to 100 parts by weight of the ether polyol (hereinafter abbreviated as "part"). That is, when the compounding amount of the isocyanate is 3
If the amount is less than 0 part, the viscosity is high and the processability is deteriorated, and the physical strength as a roller may be reduced. Conversely, if it exceeds 60 parts, the physical properties at low temperatures may be reduced. It is.

The glycol crosslinking agent used together with the above ether polyol and isocyanate is not particularly limited, but 1,4-butanediol (1,4-BD), trimethylolpropane (TMP)
And the like. These may be used alone or in combination of two or more.

The amount of the glycol-based crosslinking agent is 2 to 3 based on 100 parts of the ether-based polyol.
Preferably, it is set in the range of 0 parts. That is, if the blending amount of the glycol-based crosslinking agent is less than 2 parts, the crosslinking becomes insufficient, the physical strength is reduced, and the performance as a roller may not be satisfied. This is because the desired roller hardness may not be obtained.

The urethane rubber composition may optionally contain an amine catalyst, an ester plasticizer, and the like, as necessary.

The transport roller of the present invention is manufactured, for example, as follows. That is, first, the above-mentioned ether polyol and isocyanate are prepared, and both are mixed at an appropriate mixing ratio and reacted under appropriate conditions to prepare a urethane prepolymer. Next, a urethane rubber composition is prepared by blending and mixing the obtained urethane prepolymer, glycol-based crosslinking agent, and other additives at an appropriate ratio. Thereafter, the prepared urethane rubber composition is poured into a mold, and is heated and cross-linked under appropriate conditions to produce a cross-linked tubular body having a predetermined inner diameter (for the rubber layer 12). Then, the shaft body 11 is press-fitted into the hollow portion of the tubular cross-linked body, and the outer peripheral surface of the tubular cross-linked body is polished as necessary.
The intended transport roller can be obtained.

In the transport roller thus obtained, the hardness of the rubber layer 12 needs to be set in the range of 60 to 90 Hs according to JISA. According to the present invention, if a urethane rubber composition is used as the material for forming the rubber layer 12 and the hardness of the rubber layer 12 is set within the above range, the slip ratio can be reduced and good paper conveyance can be realized. This is because it is the most distinctive feature. In addition,
The preferred range of the hardness of the rubber layer 12 is 70 to JIS A.
80 Hs.

The diameter of the transport roller is appropriately set according to the device to be incorporated, but is usually set in the range of 10 to 40 mm. The thickness of the rubber layer 12 is 2 to 1
Preferably, it is set in the range of 0 mm.

Next, examples will be described together with comparative examples.

First, prior to Examples and Comparative Examples, the following components were prepared.

[Ether polyol] Polytetramethylene ether glycol (PTMG).

[Isocyanate] 4,4'-diphenylmethane diisocyanate (MDI).

[Glycol-based crosslinking agent] 1,4-butanediol (1,4-BD).

[Plasticizer] Polyetherester plasticizer.

[0029]

Example 1 A urethane prepolymer was prepared by a conventionally known method using 100 parts of the above ether polyol and 60 parts of isocyanate. Next, 6 parts of the above glycol-based crosslinking agent was added to the urethane prepolymer and mixed to prepare a urethane rubber composition. Thereafter, the urethane rubber composition is injected into a mold, and is heated and cross-linked to form a cross-linked tubular material (inner diameter of 11 m).
m, thickness 4 mm). Then, a shaft (core: 12 mm in diameter, SU) is inserted into the hollow portion of the obtained tubular cross-linked body.
After press-fitting S304), the outer peripheral surface of the tubular cross-linked body is polished so that the conveying roller (diameter: about 2 mm) is formed.
0 mm). The hardness of the rubber layer of the transport roller was 90 Hs according to JIS A. In addition, the said grinding | polishing process was performed by performing cylindrical grinding | polishing with respect to the outer peripheral surface of a tubular crosslinked body.

[0030]

Example 2 A transport roller was produced in the same manner as in Example 1 except that the amount of the isocyanate was changed to 40 parts. The hardness of the rubber layer of this transport roller is 80 Hs according to JIS A.
Met.

[0031]

Example 3 A transport roller was produced in the same manner as in Example 1 except that the amount of isocyanate was changed to 30 parts. The hardness of the rubber layer of this transport roller is 70 Hs according to JIS A.
Met.

[0032]

Example 4 A transport roller was produced in the same manner as in Example 3 except that 20 parts of a plasticizer was added. The hardness of the rubber layer of this transport roller was 60 Hs according to JIS A.

[0033]

Comparative Example 1 A transport roller was produced in the same manner as in Example 4 except that the amount of the plasticizer was changed to 40 parts. The hardness of the rubber layer of this transport roller was 50 Hs according to JIS A.

[0034]

Comparative Example 2 A transport roller was manufactured in the same manner as in Example 4, except that the amount of the plasticizer was changed to 60 parts. The hardness of the rubber layer of this transport roller was 40 Hs according to JIS A.

[0035]

Comparative Example 3 100 parts of EPDM, 5 parts of ZnO, 100 parts of carbon black, 25 parts of a softening agent, 30 parts of a white filler, 1.0 part of sulfur, and 5.7 parts of a vulcanization accelerator Was prepared. Then, using this rubber composition, a transport roller was produced in the same manner as in Example 1. The hardness of the rubber layer of this transport roller is 9 according to JIS A.
It was 0 Hs.

[0036]

Comparative Example 4 A transport roller was produced in the same manner as in Comparative Example 3, except that the amount of carbon black was changed to 60 parts.
The hardness of the rubber layer of this transport roller is 80H according to JIS A.
s.

[0037]

Comparative Example 5 A transport roller was produced in the same manner as in Comparative Example 3, except that the compounding amount of carbon black was changed to 50 parts and the compounding amount of the softener was changed to 50 parts. The hardness of the rubber layer of this transport roller was 70 Hs according to JIS A.

[0038]

Comparative Example 6 A transport roller was produced in the same manner as in Comparative Example 5, except that the amount of the softener was changed to 70 parts. The hardness of the rubber layer of this transport roller was 60 Hs according to JIS A.

The friction coefficient, nip width, and slip ratio of the thus obtained transport rollers of the example and comparative examples were measured by the following methods. The results are shown in Tables 1 and 2 below.

[Coefficient of friction] The coefficient of friction was calculated according to the following procedure.
Derived according to The roller is fixed to the drive shaft, and a load W is applied from the lower vertical direction. The paper is set between the roller and the push-up plate, and the roller is driven. The paper is directly connected to the load cell, and the force F at which the rollers try to convey the paper is measured. The friction coefficient μ is calculated by an equation (μ = F / W).

[Nip Width] Ink was applied to the surface of the roller, and the roller was brought into contact with the opposite roller while applying a predetermined load. The width of the ink portion adhering to the opposite roller at that time was actually measured.

[Slip ratio] The transport roller was assembled in a measuring jig and moved in a low-temperature and low-humidity environment (15 ° C × 10%). In addition, as a partner roller to be in contact with the transport roller,
A roller having a polyacetal resin layer formed on the outer periphery of a cored bar was used. Further, the rotation speed of the transport roller is set to 200 mm /
Seconds, and the sandwiching load was set to 1 kgf. In addition, a load corresponding to the load of the paper supply unit (the force required to pull out the paper from the paper supply unit) was applied to the paper (800).
g). Furthermore, high-quality paper A4 (comine, basis weight 6)
4 g / m ² ). Then, under the above conditions, the time when the high-quality paper A4 passed between the transport roller and the partner roller (A4 longitudinal feed) was measured, and the actually measured value (mm) of the paper transport amount was calculated from the measured value. On the other hand, the slip amount was calculated from the measured value and the theoretical value of the paper transfer amount using the length of the high-quality paper A4 in the vertical direction (297 mm) as the theoretical value of the paper transfer amount (slip amount = theoretical value−actual measurement). value). And
The slip ratio was calculated using the slip amount.

[0043]

[Table 1]

[0044]

[Table 2]

From the results shown in Tables 1 and 2, it was confirmed that all of the products of Examples have a small slip ratio and can carry the paper in a good condition. On the other hand, the products of Comparative Examples 1 and 2 were low in hardness, so the slip ratio was large (2 times or more), and it was confirmed that the paper could not be transported in a good state. Further, Comparative Examples 3 to 6 have substantially the same coefficient of friction as Examples 1 to 4 but have a large slip ratio (2 times or more) because of the use of EPDM. It was confirmed that the transfer could not be performed in a good condition.

[0046]

As described above, the transport roller according to the present invention is a transport roller that rotates in contact with a mating roller, and includes a shaft and a rubber layer formed along the outer periphery of the shaft. Provided, the rubber layer is made of a urethane rubber composition,
The hardness is set in the range of JIS A 60 to 90 Hs. Therefore, the slip ratio can be reduced, and the setting of the registration rollers necessary for high-precision paper conveyance,
Control becomes easy. As a result, stable paper conveyance can be performed without causing paper conveyance failure such as skew. When the transport distance is short, a registration roller for aligning the leading edge of the paper is not required, so that the number of components can be reduced and the size can be reduced. Further, cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating an example of a transport roller of the present invention.

FIG. 2 is a schematic explanatory diagram for explaining a sheet feeding device.

[Explanation of symbols]

 11 Shaft 12 Rubber layer

Claims (1)

[Claims] 1. A conveying roller which rotates while being in contact with a mating roller, comprising: a shaft; and a rubber layer formed along an outer periphery of the shaft, wherein the rubber layer is made of a urethane rubber composition. A conveying roller having a hardness set in the range of JIS A 60 to 90 Hs.