JPH1111731A - Carrier roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier roller that can prevent the generation of a recessed part to paper on the assumption that it is made of plastic. SOLUTION: A carrier roller 13 is composed of an outer peripheral part 13a, a shaft part 13b, a mass removing part 13c and a connection part 13d, and the connection part 13d coincides with a die split face. A recessed part 13e is therefore formed in the die split face corresponding position of the outer peripheral part 13a, so that a burr generated at this part is held into a lower position than a flat part 13g of the outer peripheral part 13a so as not to come in contact with paper. Since both ends of the outer peripheral part 13a are tapered parts 13f, even though the carrier roller 13 is formed into drum shape due to molding shrinkage difference, no edge is generated to both end parts. With both ends of the outer peripheral part 13 formed into curved parts, paper can be conveyed, normally even though partial contact is generated to the carrier roller 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transport roller suitable for a paper transport path of an image forming apparatus such as a copying machine or a printer, and more particularly to a cylindrical roller having a hollow portion between an outer peripheral portion and a shaft portion, or It relates to a drum-shaped plastic transport roller.

[0002]

2. Description of the Related Art In many cases, a plastic transport roller used in an image forming apparatus such as a copying machine or a printer is used in contact with a rubber transport roller. Generally, the transport roller has a cylindrical shape, and between the outer peripheral portion and the shaft portion,
In order to prevent dimensional defects due to molding shrinkage, lightening corresponding to the size of the outer shape is provided.

FIG. 10 is a sectional view of a general transport roller. As described above, the cylindrical transport roller 1 includes an outer peripheral portion 1a, a shaft portion 1b, a lightened portion 1c formed therebetween, and a connecting portion (connecting meat) 1d for connecting the outer peripheral portion 1a and the shaft portion 1b. Have.

The transport roller and the transport roller are in contact with each other, and the paper is transported by sandwiching the paper between the nips.
Here, the transport roller is distinguished as the drive side and the transport roller is distinguished as the driven side.

Incidentally, in an image forming apparatus having a double-sided copying mechanism, when the double-sided copying mode is executed, the first
The paper is likely to curl due to heat after the surface (front) fixing. If the curled sheet is conveyed as it is, the sheet may be wrinkled. Therefore, there is a technique for inclining the drive roller and the conveying roller in a certain direction with respect to the sheet advancing direction.

On the other hand, in the case of transporting thick paper, different from the case of transporting ordinary paper, special consideration must be given to thick paper. That is, when conveying thick paper, it is necessary to increase the conveying force by the conveying rollers and the conveying rollers as compared with the case of normal paper. In order to increase the conveying force, it is necessary to increase not only the driving torque but also the clamping force of the nip portion (the pressing force of the conveying roller against the conveying roller).

FIG. 11 is a side view showing a press-contact mechanism of the conveying roller and the conveying roller, and FIG. 12 is a front view of the same. Conveyance roller 1
Is pressed by a leaf spring 2 against a transport roller 3 having a surface formed of an elastic material such as rubber. The leaf spring 2 is a sheet P
The transport roller 1 is axially supported between both side plates at its free end.

[0008]

FIG. 13 is a front view of a transport mechanism including a transport roller and a transport roller formed of a cylindrical plastic molded product. When a cylindrical plastic molded product is used as the transport roller 1, as shown in FIG. 13, sink marks occur at the center due to a difference in molding shrinkage, and the drum becomes a drum shape. Hits strongly.

FIG. 14 is a view showing a concave portion of a sheet conveyed by the conveying mechanism shown in FIG. As shown in FIG. 14, the sheet P with which the edges 1a and 1b of the transport roller 1 contact
A small concave portion represented by Pa and Pb is generated in the portion.
If the surface where the concave portions Pa and Pb are generated is the image transfer surface, the image is not transferred to the concave portions Pa and Pb, and a problem of white stripes (white spots) occurs.

FIG. 15 is a perspective view of a drum-shaped (a central portion in the axial direction has an enlarged diameter; a crown shape) plastic transport roller showing a conventional example. Also in the case of using a crown-shaped plastic transport roller 5 which is a known technique for eliminating the drum shape, in the related art, as shown in FIG. 15, a mold dividing surface (slide line) 5a is formed on the outer peripheral surface of the transport roller. In addition, since a step, a burr, and the like are generated on the mold dividing surface 5a, the transport roller 5 cannot be used unless a third member such as a rubber belt (not shown) is used.

Incidentally, in order to solve the above-mentioned problem caused by forming the transport rollers 1 and 5 as plastic molded products, it is conceivable that the transport rollers are formed by elastic members similarly to the transport roller 3. Component processing costs are tens of times higher than plastic molded products, and the cost effectiveness is significantly reduced.

The present invention has been made in view of such a background, and an object of the present invention is to provide a transport roller that can be made of plastic and that can prevent the occurrence of a concave portion in a sheet.

[0013]

In order to achieve the above object, the invention according to claim 1 is directed to a cylindrical or drum-shaped plastic conveying roller in which lightening is performed between an outer peripheral portion and a shaft portion. By forming a mold dividing surface on the outer peripheral portion corresponding to a connecting portion inside the transport roller connecting the outer peripheral portion and the shaft portion, a concave portion is formed at a position of the mold dividing surface on the outer peripheral portion. It is assumed that.

According to a second aspect of the present invention, in the first aspect, both ends of the outer peripheral portion are tapered.

According to a third aspect of the present invention, in the first aspect of the invention, the thickness of the connecting portion is larger than the thickness of the outer peripheral portion.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a curved surface portion is provided at a portion where the connecting portion and the inner surface of the outer peripheral portion abut.

According to a fifth aspect of the present invention, in the first aspect of the invention, both ends of the outer peripheral portion are curved portions.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a duplex unit of a copying machine to which the present invention is applied, and FIG.

The basic flow of paper will be described with reference to these drawings. The paper separated and conveyed one by one from the paper feeding unit is transferred with an image by a transfer unit, and the image is fixed by a fixing unit. The sheet is inverted only when the double-side mechanism is selected in the subsequent reversing unit, and the sheet is conveyed to the lower duplex unit (not shown).

The paper entering the double-sided unit shown in FIG. 1 is detected by the paper-entry detecting section 11 to be jammed, and is transported rightward on the transport path 14 by the transport rollers 12 and the transport rollers 13. The transport roller 12 is driven by a double-sided motor 15 (FIG. 2) via a gear and a timing belt (FIG. 2).

Thereafter, when the sheet is detected by the reversal detecting section 16, the sheet is guided by the switching claw 17 in the direction of reversing along the feed roller 18 at the time of duplex copying. Also,
In the case of the synthesizing function of superimposing images instead of double-sided images, the images are sent to the grip conveying roller 19 without being inverted. The inverted sheet is sent to the separation roller 20. The separation roller 20 has a built-in one-way clutch. The shaft and the one-way clutch slide during stacking, and the separation roller 20 is rotated by the feed roller 18.

At the time of stacking, the bottom plate 21 waits downward and does not prevent the paper from entering. When paper enters the double-sided tray, the side fence 2
2 and the end fence 23 move to align the paper.
When a predetermined number of sheets have been stacked, the double-sided conveyance motor 1
5, the feed roller 18 starts rotating in the re-feeding direction, the bottom plate 21 is raised by a spring clutch (not shown), and presses the sheet against the feed roller 18.

The paper is re-supplied by the feed roller 18 in order from the uppermost sheet of the stacked paper, and is sent to the grip conveying roller 19. Separation of the sheets at the time of refeeding is performed by the separation roller 20, and the one-way clutch built in the separation roller 20 locks with the shaft, so that the separation roller 20 stops, and two sheets are separated by the frictional force of the surface. Prevents paper after the first eye from being conveyed.

In FIG. 1, reference numeral 24 denotes a paper end detection unit, 25 denotes a side fence HP (home position) detection unit, and 26 denotes an end fence HP detection unit.

FIG. 3 is a perspective view of the transport mechanism in the duplex unit shown in FIG. The transport roller 13 is made of a plastic molded product, and the shafts 31, 31 on both sides are rotatably mounted in holes 32a, 32a of a support plate 32 made of a leaf spring material. By using the effect described above, the transport roller 13 is pressed toward the transport roller 12.

The transport roller 12 is composed of an elastic rubber roller fixed to a metal shaft 33. When the transport roller 12 rotates in the direction of the arrow, the transport roller 13 also moves due to the frictional resistance of its surface. Follow the direction A.

FIG. 4 is a sectional view of a transport roller according to the first embodiment of the present invention. The transport roller 13 includes an outer peripheral portion 13a, a shaft portion 13b, and a lightening portion 1 as in the conventional example shown in FIG.
3c, and has a connecting portion 13d at the center of the lightening. In the outer peripheral portion 13a, a position corresponding to the connecting portion 13d is a concave portion 13e, and both ends of the outer peripheral portion 13a are tapered portions 13f, 13f. That is, the outer peripheral portion 1
The concave portion 13e and the tapered portion 1 correspond to the flat portion 13g of FIG.
3f is dented. The concave portion 13e and the tapered portion 13f do not come into contact with the surface of the transport roller 12 made of a rubber material. Therefore, it does not come into contact with the paper.

The position of the connecting portion 13d is generally brought to the center of the transport roller 13 in the longitudinal direction from the viewpoint of the mold structure and moldability. The concave portion 13e is generated when the outer peripheral portion 13a is pulled inward by molding shrinkage due to the presence of the connecting portion 13d.

FIG. 5 is a sectional view of a mold for molding the transport roller of the present invention. The mold 41 is configured such that the divided surfaces (parting lines) 42 of the right and left molds coincide with the connection portion corresponding grooves 45 corresponding to the connection portions 13 d of the transport roller 13. Reference numeral 43 denotes an outer peripheral portion corresponding groove corresponding to the outer peripheral portion 13a, and reference numeral 44 denotes a shaft portion corresponding groove corresponding to the shaft portion 13b. The outer peripheral portion corresponding groove 43 has a shape in which the tapered portions 13f, 13f are formed.

By aligning the mold dividing surface 42 with the connecting portion corresponding groove 45 in this manner, as shown in FIG.
A recess 13e can be formed in 3a. Here, by making the interval T between the connecting portion corresponding grooves 45, in other words, the thickness T of the connecting portion 13d, larger than the interval t of the outer peripheral portion corresponding groove 43, in other words, the thickness t of the outer peripheral portion 13a, more effective. Becomes That is, a sink is intentionally generated on the mold dividing surface 42 of the transport roller 13. In addition, the tapered portion 13f has a shape in which the mold dividing surface 42 is provided at the central portion in the longitudinal direction of the transport roller 13, so that the taper portion 13f can be released from the mold in a normal die removing direction.

FIG. 6 is a sectional view showing a state in which burrs are generated in the concave portion of the transport roller shown in FIG. Mold dividing surface 42
Generates a step and burrs 13h as shown in FIG.
The place where the burr 13h occurs is the recess 13e, and the burr 13h
Is lower than the flat portion 13g of the outer peripheral portion 13a, so that the burrs 13h do not abut on the sheet to form a dent on the sheet. Generally, steps and burrs generated by plastic molding are about 0.02 to 0.03 mm.
The thickness of the flat portion 13g other than 3f may be set to about 0.05 mm.

FIG. 7 is a sectional view of a transport roller according to a second embodiment of the present invention. A curved portion (R) 13 is provided on the contact portion between the connecting portion 13d of the transport roller 13 and the inside of the outer peripheral portion 13a.
Also by forming i, 13i, the concave portion 13e can be formed in the outer peripheral portion 13a of the transport roller 13 corresponding to the mold dividing surface 42. It is needless to say that the transport roller 13 has the same effect as the transport roller 13 of the first embodiment. In this case, the connecting portion 13 of the transport roller 13
Since the thickness T of d does not need to be increased, and the cooling time during molding can be shortened, it is more effective.

FIG. 8 is a sectional view of a transport roller according to a third embodiment of the present invention. The transport roller 13 of this embodiment
Is provided with curved surface portions 13j, 13j at both ends of the outer peripheral portion 13a.

FIG. 9 is a view showing a state in which the transport roller shown in FIG. 8 is in contact with the transport roller in an inclined state. As shown in FIG. 9, even when the conveying roller 13 is in one-side contact with the conveying roller 12, the curved surface portions 13 j are provided at both ends of the conveying roller 13. The paper does not hurt. From the above, it is possible to prevent white streaks (white spots) during double-sided copying even with the use of inexpensive rollers for transporting plastic molded products.

The transport roller 13 according to the embodiment of the present invention includes an outer peripheral portion 13a, a shaft portion 13b, a lightening portion 13c, and a connecting portion 13.
d, and the connecting portion 13d and the mold dividing surface 42 are aligned. Therefore, since the concave portion 13e is formed at the position corresponding to the mold dividing surface of the outer peripheral portion 13a, the burr 13h generated at this portion is pressed to a position lower than the flat portion 13g of the outer peripheral portion 13a so as not to come into contact with the sheet. be able to.

Further, both ends of the outer peripheral portion 13a are tapered portions 13a.
Since f is set, edges do not occur at both ends even if the transport roller 13 has a drum shape due to a difference in molding shrinkage.
Further, if both ends of the outer peripheral portion 13a are curved surfaces 13j, the sheet can be conveyed normally even if the conveying roller 13 has one side contact.

[0037]

According to the first aspect of the present invention, a mold dividing surface is formed on the outer peripheral portion corresponding to the connecting portion inside the transport roller connecting the outer peripheral portion and the shaft portion, so that the outer peripheral portion is formed. Since the concave portion is formed at the mold dividing surface position, the step and the burr generated on the mold dividing surface do not have to be exposed to the outer peripheral surface of the transport roller. As a result, even if the pressing force between the transport rollers and the transport rollers is increased, it is possible to prevent the occurrence of white streaks (white spots) in the image on the paper.

According to the second aspect of the present invention, since both ends of the outer peripheral portion are tapered, even if the conveying roller has a drum shape due to a difference in molding shrinkage, both ends do not abut against the opposing conveying rollers. It is possible to do so.

According to the third aspect of the present invention, since the thickness of the connecting portion is made thicker than the thickness of the outer peripheral portion, the sink effect during molding can be utilized to the utmost, and the mold generation surface can be more reliably generated on the mold dividing surface. Steps and burrs can be prevented from being exposed on the outer peripheral surface of the transport roller.

According to the fourth aspect of the present invention, since the curved portion is provided at the portion where the connecting portion and the inner surface of the outer peripheral portion are in contact with each other, similarly to the above, the sinking effect at the time of molding can be utilized to the utmost. Steps and burrs generated on the mold division surface can be reliably prevented from being exposed to the outer peripheral surface of the transport roller.

According to the fifth aspect of the present invention, since both end portions of the outer peripheral portion are curved portions, the sheet can be received by the curved portion even if one end of the transport roller and the transport roller occurs at the time of transporting the paper. Therefore, it is possible to prevent the occurrence of image defects such as white stripes without damaging the paper.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a duplex unit of a copying machine to which the present invention is applied.

FIG. 2 is a perspective view of a main part of the same.

FIG. 3 is a perspective view of a transport mechanism in the duplex unit shown in FIG.

FIG. 4 is a sectional view of a transport roller showing the first embodiment of the present invention.

FIG. 5 is a cross-sectional view of a mold for molding the transport roller of the present invention.

FIG. 6 is a cross-sectional view showing a state in which burrs are generated in a concave portion of the transport roller shown in FIG.

FIG. 7 is a cross-sectional view of a transport roller according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a transport roller showing a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a state in which the conveyance roller illustrated in FIG. 8 is in contact with a conveyance roller in a tilted state.

FIG. 10 is a sectional view of a general transport roller.

FIG. 11 is a perspective view illustrating a pressing mechanism of a transport roller and a transport roller.

FIG. 12 is a front view of the same.

FIG. 13 is a front view of a transfer mechanism including a transfer roller and a transfer roller formed of a cylindrical plastic molded product.

FIG. 14 is a diagram illustrating a concave portion of the sheet conveyed by the conveyance mechanism illustrated in FIG. 13;

FIG. 15 is a perspective view of a drum-shaped plastic transfer roller showing a conventional example.

[Explanation of symbols]

 13 Conveyance roller 13a Outer peripheral portion 13b Shaft portion 13c Lightening portion 13d Connecting portion 13e Depressed portion 13f Tapered portion 13g Flat portion

Claims (5)

[Claims] 1. A cylindrical or drum-shaped plastic transport roller having a hollow portion between an outer peripheral portion and a shaft portion, which corresponds to a connecting portion inside the transport roller connecting the outer peripheral portion and the shaft portion. A transfer roller, wherein a concave portion is formed at a position of a mold dividing surface on an outer peripheral portion by forming a mold dividing surface on an outer peripheral portion. 2. The transport roller according to claim 1, wherein both ends of the outer peripheral portion are tapered. 3. The transport roller according to claim 1, wherein the thickness of the connecting portion is larger than the thickness of the outer peripheral portion. 4. The transporting roller according to claim 1, wherein a curved portion is provided at a portion where the connecting portion and the inner surface of the outer peripheral portion abut. 5. The transport roller according to claim 1, wherein both ends of the outer peripheral portion are curved surfaces.