JP4071168B2 - Roller shaft and roller - Google Patents

Description

【００４０】
【発明の効果】
以上説明したように、本発明のローラ用シャフトは、各種ローラ用のシャフトとして利用する場合に、研磨や、成形金型内で逆センタ保持する際の、シャフトの外径の寸法精度のバラつきによらず安定したシャフト保持が可能となり、振れの小さいローラを提供することができる。
【図面の簡単な説明】
【図１】本発明のローラ用シャフトの実施の形態の一例を示す端部拡大図である。
【図２】本発明の実施例１のローラ用シャフトの端部拡大図である。
【図３】本発明のローラ用シャフトと逆センタとの接触部の拡大図である。
【図４】 比較例１のローラ用シャフトの端部拡大図である。
【図５】比較例１のローラ用シャフトと逆センタとの接触部の拡大図である。
【図６】実施例２および比較例２のローラの作製に用いた成形金型の断面図である。
【符号の説明】
１ ローラ用シャフト
２ Ｃ面取り部
３ R面取り部
４ 逆センタ
５ａ 直径の寸法公差が最大値のときのローラ用シャフトと逆センタとの接触位置
５ｂ 直径の寸法公差が最小値のときのローラ用シャフトと逆センタとの接触位置
１１ 下部駒
１２ パイプ型
１３ 上部駒
１４ スライド
１５ 圧縮バネ[0001]
[Technical field to which the invention belongs]
The present invention relates to a roller shaft that can be used as a shaft of various rollers used in an electrophotographic apparatus such as a laser beam printer, and a roller using the roller shaft.
[0002]
[Prior art]
In general, an electrophotographic apparatus such as a laser beam printer uses various rollers such as a charging roller, a developing roller, a transfer roller, a fixing roller, a pressure roller, and a paper feeding roller. As shown in FIG. 4, the shafts used for these rollers are generally chamfered at the corners of the ends of the shaft 1.
[0003]
These rollers are required to have a predetermined outer diameter accuracy, runout accuracy, and surface accuracy depending on the application. In order to meet this requirement, these rollers are used, for example, by inserting the shaft 1 into an elastic body produced by extruding it into a tube shape, covering the outer periphery of the shaft 1 with an elastic body layer, and achieving a predetermined accuracy. The shaft 1 is set in a molding die that can be manufactured by polishing the elastic layer or a roller can be formed with a predetermined accuracy, and a rubber material is inserted into the cavity of the molding die and heat-cured. Then, an elastic body layer is formed on the outer peripheral portion of the shaft 1, and if desired, the elastic body layer is further polished.
[0004]
When polishing, as shown in FIG. 5, in order to improve runout accuracy, the corners of the shaft are held by a support body 4 having a mortar-shaped concave portion called a reverse center. In addition, when the elastic layer is formed using a molding die, the shaft support portion of the molding die may have a mortar-like concave portion in the same manner as the reverse center in order to improve runout accuracy.
[0005]
Generally, even if the C-chamfering angle θ2 of the shaft 1 and the taper angle θ4 of the reverse center 4 are set to be the same, it is impossible to bring the shaft 1 and the reverse center 4 into surface contact due to processing accuracy. For this reason, the angle θ2 of the C chamfered portion of the normal shaft 1 and the taper angle θ4 of the reverse center 4 are different.
[0006]
For example, when the taper angle θ4 of the reverse center 4 is smaller than the C-chamfering angle θ2 of the shaft 1, the shaft 1 contacts the reverse center 4 at the outer diameter side edge of the C-chamfered portion. When polishing the elastic layer of the roller or the like, if the holding force of the reverse center 4 is increased so that the roller does not slip, the outer diameter side edge of the C chamfered portion of the shaft 1 is crushed, and the outer diameter of the shaft 1 is reduced. May be slightly larger. When the outer diameter of the shaft is increased, problems such as the shaft being unable to be inserted occur when a roller is incorporated into the printer body or when the shaft is attached to a bearing or a driving gear.
[0007]
Further, when the taper angle θ4 of the reverse center 4 is larger than the angle θ2 of the C chamfered portion of the shaft 1, the shaft 1 contacts the reverse center 4 at the edge on the end surface side of the C chamfered portion. In this case, problems such as an insufficient centering effect and a decrease in holding force of the reverse center 4 occur.
[0008]
In general, the diameter φD of the shaft 1 varies within an allowable tolerance. For this reason, the chamfering amount also varies, the contact position 5a (5b) with the holding jig such as the reverse center 4 changes, and the position where the shaft 1 is held varies. For example, when the taper angle θ4 of the reverse center 4 is smaller than the angle θ2 of the C-chamfered portion of the shaft 1, the maximum variation ΔL of the shaft diameter φD is D1 and the minimum value ΔL in the shaft axial direction of the contact position. Where D2 is (D1−D2) / 2 × tan (θ4). When the holding position of the shaft 1 varies in this way, there is a problem that sufficient runout accuracy cannot be obtained depending on the applied roller.
[0009]
As a method for preventing the contact portion of the holding member with the reverse center 4 or the like from being crushed and the outer diameter of the shaft 1 from expanding, a method in which the chamfered portion has two steps has been proposed (see, for example, Patent Document 1). However, this method can prevent the contact portion between the shaft 1 and the holding member such as the reverse center 4 from being crushed, but it cannot prevent the holding position from being varied due to the variation in the diameter φD of the shaft 1. .
[0010]
[Patent Document 1]
JP 2000-145761 A (Claim 1)
[0011]
[Problems to be solved by the invention]
Therefore, the present invention provides a polishing process and a molding metal when used as a shaft of various rollers such as a charging roller, a developing roller, a transfer roller, a fixing roller, a pressure roller, and a paper feeding roller used in an electrophotographic apparatus. To provide a shaft for various rollers that can stably hold a shaft regardless of variations in the dimensional accuracy of the shaft when holding the roller or the shaft in an elastic layer forming process using a mold or the like. An object is to provide various rollers using the same.
[0012]
[Means for Solving the Problems]
According to the present invention, in the roller shaft, the chamfered portion created at the end corner of the shaft is configured from the end surface side of the shaft in the order of the R chamfered portion and the C chamfered portion in contact with the R chamfered portion. It is the shaft for rollers characterized by having.
[0013]
In the roller shaft of the present invention, the center position of the R chamfered portion is dimensioned from the shaft center of the shaft, and the angle at which the R chamfered portion of the shaft is created is less than 90 ° with respect to the shaft axis. It is preferable that the C chamfered portion in contact with the R surface is created up to the outer diameter of the shaft.
[0014]
In addition, the present invention is a roller characterized by having at least one elastic layer on the outer periphery of the roller shaft of the present invention.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An example of an embodiment of the present invention is shown in FIG.
The chamfered portion created at the corner of the end of the roller shaft of the present invention is configured in the order of the R chamfered portion 3 and the C chamfered portion 2 in contact with the R chamfered portion 3 from the end surface side of the roller shaft of the present invention. Has been. The chamfered portion of the roller shaft of the present invention is determined by measuring the center position of the R chamfered portion 3 from the shaft center of the shaft, and the direction in which the outer peripheral side boundary of the R chamfered portion is expected from the center position of the R chamfered portion 3 Creates an R chamfered portion 3 until the angle becomes θ1 with respect to the shaft axis (this angle θ1 may be referred to as a creation angle of the R chamfered portion). The C chamfered portion 2 that is in contact with the portion 3 is created, and escaped to the outer diameter of the roller shaft of the present invention at an angle θ2 (may be referred to as a taper angle) with respect to the shaft central axis.
[0016]
At this time, the creation angle θ1 of the R chamfered portion 3 is generally set to (90 ° −θ4) ≦ θ1 <90 °, where θ4 is the taper angle of the reverse center that is a shaft support in polishing or mold. It is preferable to do this. If θ1 is set to (90 ° −θ4) ≦ θ1 <90 °, the shaft centering effect is enhanced because the R chamfered portion of the shaft is surely in contact with the reverse center. Further, the lower limit value of θ1 is not particularly limited, but it is usually preferably 45 ° ≦ θ1 and more preferably 60 ° ≦ θ1. Further, the taper angle θ2 of the shaft of the C chamfered portion 2 is 90 ° −θ1.
[0017]
The distance r from the shaft axis center of the center of the R chamfered portion 3 and the radius of curvature (sometimes referred to as radius) R of the R chamfered portion are the radius (φD2 / 2) when the shaft diameter φD is within the tolerance On the other hand, it is preferable to satisfy the relationship of (r + Rsin θ1) ≦ φD2 / 2, and it is more preferable to satisfy the relationship of 0.8 × φD2 / 2 ≦ (r + Rsin θ1) ≦ φD2 / 2.
[0018]
In the roller shaft of the above aspect, when the roller shaft is supported by the reverse center 4 having the taper angle θ4, the R chamfered portion 3 is positioned at an angle of (90 ° −θ4) with respect to the shaft axis of the roller shaft. And the reverse center 4 are in contact with each other. At this time, since the center of the R chamfered portion 3 is dimensioned from the shaft axis center, as shown in FIG. 3, the center is in contact with the reverse center 4 at fixed positions 5a and 5b regardless of the diameter tolerance of the roller shaft.
[0019]
In addition, since the position in contact with the reverse center 4 is inside the outer diameter of the shaft, there is no change in the outer diameter of the shaft even when the contact portion with the reverse center is crushed when the shaft is supported. The problem of not being able to enter the gears for use does not occur.
[0020]
The roller shaft of the present invention can be manufactured using an appropriate material selected from known materials according to the purpose of use of the roller manufactured using the roller shaft. Specific examples include metal materials such as iron, stainless steel, steel, brass, and aluminum, and resin materials such as nylon and polyacetal.
[0021]
Generally, using a round bar or the like produced by extrusion molding, pultrusion molding, or the like from these materials, a shaft having a predetermined length is produced by lathe processing, and the above R is formed at the corners of both ends of the shaft. A chamfered portion having a configuration having a chamfered portion and a C chamfered portion in contact with the chamfered portion is created to produce the roller shaft of the present invention.
[0022]
Usually, the C chamfered portion is created after the R chamfered portion is created, but the R chamfered portion and the C chamfered portion may be created in the reverse order. The method of creating the R chamfered portion is not particularly limited, and examples thereof include a method of machining by moving a cutting tool with a constant radius on a lathe. Further, the creation method of the C chamfered portion is not particularly limited, and examples thereof include a method of machining by applying a bit created with a lathe at the same angle as the chamfer angle. Further, it is preferable to create the C chamfered portion by moving the bite by the radius of the R chamfered portion on the lathe to create the R chamfered portion and then letting the bite escape to the shaft outer diameter at the C chamfered angle.
[0023]
The roller of the present invention has the roller shaft of the present invention and at least one elastic layer formed on the outer periphery of the roller shaft. The elastic layer of the roller of the present invention is not particularly limited, and an appropriate layer may be selected from known elastic layers according to the purpose of use of the roller. Examples of the elastic layer include polyurethane, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, acrylic rubber, chloroprene rubber, butyl rubber, and epichlorohydrin rubber. Mention may be made of an elastic body layer obtained by using rubber raw materials or monomers or the like as raw materials for producing these rubber raw materials (these monomers may also be referred to as rubber raw materials). It may be an elastic body layer obtained by combining the rubber raw materials alone or two or more of these rubber raw materials.
[0024]
Moreover, a crosslinking agent, a foaming agent (water, a low boiling point material, a gas body, etc.), a surfactant, a catalyst, and the like can be further added to these rubber raw materials, if desired. Similarly, a flame retardant, a filler, a conductivity imparting agent for imparting desired conductivity, an antistatic agent, and the like can be added to such raw materials as necessary.
[0025]
The method for producing the roller of the present invention is not particularly limited, and a suitable method can be selected from known production methods to produce the roller. The diameter and length of the roller shaft of the present invention are not particularly limited, and may have various diameters and lengths depending on the purpose. Usually, the diameter is 5 to 10 mm and the length is 240 to 240 mm. The roller shaft of the present invention of 350 mm can be produced by coating with an elastic layer. The outer diameter of the roller is not particularly limited, and may have various outer diameters depending on the purpose. In general, the outer diameter may be 10 to 30 mm.
[0026]
As a specific example of the method for producing the roller of the present invention, for example, a rubber raw material, a catalyst used as desired, a foaming agent, a cross-linking agent, a foam stabilizer and other auxiliaries are homogeneously mixed to prepare a rubber raw material composition. Then, a method for producing an elastic layer integrally by injecting the roller shaft of the present invention into a cavity of a molding die that has been previously arranged, and heating and reaction curing, Cut from a slab or block of an elastic body separately formed using an object into a predetermined shape and size such as a tube by cutting or the like, and press the roller shaft of the present invention into this to the outer periphery of the roller shaft. Examples thereof include a method of coating an elastic body layer and a method of appropriately combining these methods. If desired, it can be further adjusted to a predetermined outer diameter by cutting or polishing treatment.
[0027]
The temperature and time for mixing the rubber raw material composition are not particularly limited, and may be suitable for the rubber raw material composition to be used. When the rubber raw material composition is in a liquid state, the mixing temperature is usually in the range of 10 to 90 ° C., and the mixing time is usually about 1 second to 10 minutes.
[0028]
Further, when the reaction is cured by heating, the elastic layer can be formed by foaming by a conventionally known method. The foaming method is not particularly limited, and a method more suitable for the rubber raw material used, the foaming agent, etc. may be adopted. The expansion ratio may be appropriately determined according to the purpose of use of the roller, and is not particularly limited.
[0029]
The method for joining the roller shaft and the elastic layer of the roller of the present invention is not particularly limited, but the roller shaft of the present invention is previously placed inside a mold (molding die) and a rubber raw material composition is cast and cured. And a method of cutting out from a separately formed elastic body slab or block into a predetermined shape and size or forming the elastic body into a predetermined shape and then bonding it to the roller shaft of the present invention. it can. In either method, an adhesive layer can be provided between the roller shaft of the present invention and the elastic body layer as necessary. As the adhesive layer, a known material such as an adhesive or a hot melt sheet can be used.
[0030]
The temperature and time for curing the rubber raw material composition are not particularly limited, and may be suitable for the rubber raw material composition to be used.
[0031]
【Example】
Hereinafter, an embodiment in which the roller shaft of the present invention is applied to molding of a developing roller for electrophotography will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.
[0032]
Example 1 Production of Roller Shaft FIG. 2 is an enlarged view of the end of the roller shaft of this example.
The roller shaft 1 of this embodiment has a length of 260 mm and a diameter φD of 8 mm. At the corners of both ends of the roller shaft 1 of this embodiment, there are chamfered portions composed of an R chamfered portion and a C chamfered portion in contact with the C chamfered portion from the end surface side of the shaft. It has a shape. The material of the roller shaft 1 of this embodiment is free-cutting steel SUM23L. In addition, the dimensional tolerance of the diameter φD of the roller shaft of this example was set to plus 0, minus 0.05 mm.
[0033]
The radius R of the chamfered portion is 1.5 mm, the center position r of the R chamfered portion is 2.5 mm from the shaft axis center (1.4 mm from the shaft end surface), and the creation angle θ1 of the R chamfered portion is 75 °, and the C chamfered The taper angle θ2 of the portion was 15 °. The R chamfered part and C chamfered part use a lathe to move the bite from the central axis side of the shaft with the radius of the R chamfered part to create the R chamfered part. Created.
[0034]
Comparative Example 1 Production of Roller Shaft FIG. 4 is an enlarged view of the end of the roller shaft of this comparative example.
The roller shaft 1 of this comparative example was produced in the same manner as in Example 1 except that the chamfered portions provided at the corners at both ends were changed to a C chamfered portion having a width of 1 mm and a taper angle of 45 °.
[0035]
[Example 2 and Comparative Example 2] Fabrication of Roller FIG. 6 shows a cross-sectional view of a molding die used for manufacturing the roller of this example and the comparative example. This molding die has a pipe mold 12 having a cylindrical shape with a cavity inner diameter φD of 16 mm and a length of 240 mm, and three parts including an upper piece 13 and a lower piece 11 fitted to both ends of the pipe mold. It is a mold. Both parts are made of pre-hardened steel. The lower piece 11 has eight holes with an inner diameter φD of 1.8 mm at equal intervals in the circumferential direction as material injection holes, and the upper piece 13 is used for air bleeding and overflow of the rubber raw material composition. Four holes with an inner diameter φD of 1.5 mm are formed at equal intervals in the circumferential direction.
[0036]
Further, in order to hold the corners of both ends of the roller shaft in the mold, the upper piece 13 has a reverse center structure, the lower piece 11 has a reverse center structure slide 14, and the compression spring 15 pushes the slide 14, and the shaft It was set as the structure which hold | maintains the corner | angular. The taper angle θ4 of the reverse center was set to 30 ° for both the upper piece 13 and the lower piece slide 14, and the compression spring 15 was set to a spring constant of 10 N / mm and a holding load of 9.8 N.
[0037]
Two liquids having a viscosity of 150 Pa · s at a temperature of 25 ° C. as a rubber raw material composition from a material injection nozzle in which the roller shaft of Example 1 or Comparative Example 1 is disposed on the molding die and pressed against the lower piece 11. In order to give conductivity to the mixed type thermosetting silicone rubber, a rubber raw material composition containing carbon black is injected, and the temperature of the molding die is set to 110 ° C. and heated for 5 minutes to be thermally cured, and the developing roller Was made. Measure the gap from the reference to the outer diameter of the developing roller at the center of the developing roller using the laser dimension measuring instrument manufactured by Keyence Corporation, and subtract the minimum value from the maximum value of the gap. The value was measured as runout. Further, 100 runouts of each of the developing rollers of Example 2 and Comparative Example 2 were measured, and an arithmetic average and a standard deviation were obtained. The obtained results are shown in Table 1.
[0038]
The developing roller of Example 2 manufactured using the roller shaft of Example 1 has smaller runout and smaller standard deviation than the developing roller of Comparative Example 2 manufactured using the roller shaft of Comparative Example 1. There is little variation in runout. Further, when the holding position of the roller shaft is calculated, the holding position does not change in the roller shaft of Example 1 even if the shaft diameter φD changes within the tolerance, whereas in the roller shaft of Comparative Example 1, When the shaft diameter φD changes within the tolerance, the holding position of the shaft changes by 0.05 mm on one side and by a maximum of 0.1 mm on both sides, and the holding load resulting from this changes by about 0.98 N.
[0039]
[Table 1]

[0040]
【The invention's effect】
As described above, the roller shaft of the present invention has a variation in the dimensional accuracy of the outer diameter of the shaft when polished or held in a reverse center in a molding die when used as a shaft for various rollers. Regardless of this, stable shaft holding is possible, and a roller with small runout can be provided.
[Brief description of the drawings]
FIG. 1 is an enlarged end view showing an example of an embodiment of a roller shaft according to the present invention.
FIG. 2 is an enlarged view of an end portion of the roller shaft according to the first embodiment of the present invention.
FIG. 3 is an enlarged view of a contact portion between a roller shaft and a reverse center according to the present invention.
4 is an enlarged view of an end portion of a roller shaft of Comparative Example 1. FIG.
FIG. 5 is an enlarged view of a contact portion between a roller shaft and a reverse center according to Comparative Example 1;
6 is a cross-sectional view of a molding die used for manufacturing the rollers of Example 2 and Comparative Example 2. FIG.
[Explanation of symbols]
1 Roller shaft 2 C chamfered portion 3 R chamfered portion 4 Reverse center 5a Contact position 5b between the roller shaft and the reverse center when the dimensional tolerance of the diameter is the maximum value Roller shaft when the dimensional tolerance of the diameter is the minimum value And lower center contact position 11 Lower piece 12 Pipe type 13 Upper piece 14 Slide 15 Compression spring

Claims (3)

In the shaft for a roller, the chamfered portion created at the corner of the end portion of the shaft is configured from the end surface side of the shaft in the order of an R chamfered portion and a C chamfered portion in contact with the R chamfered portion. Characteristic roller shaft. The center position of the R chamfered portion is dimensioned from the axial center of the shaft, and the angle at which the R chamfered portion of the shaft is created is less than 90 ° with respect to the shaft axis, and the C chamfer is in contact with the R surface The roller shaft according to claim 1, wherein the portion is created up to the outer diameter of the shaft. A roller having at least one elastic layer on the outer periphery of the roller shaft according to claim 1.

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