JP2000266038A - Tube fixing method for roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the dispersion and remarkably improve the accuracy of an outside diameter by covering a sponge rubber material with a thermal shrink able tube in such manner that the sponge rubber material is wrapped, and fixing both ends of the tube near both ends of the sponge rubber material. SOLUTION: A thermally shrinkable resin tube 3 is placed in a heating furnace so that the resin tube 3 is closely contacted with the sponge rubber 6 by the thermal shrinkage thereof. Then the stopper tools 4 are moved in the direction of an arrow to be press fit into a holding member is such manner that the ends of the remarkably shrinked resin tube 3 are held thereby. The stopper tools 4 are respectively provided with projections 12 to be fitted in the groves 9 of the holding member, on their peripheral surfaces at a point end. Accordingly, protrusion when the stopper tools 4 are press fit into the holding member 5, the parts of the stopper tools are fitted into the recess parts of the holding member 5 while holding the remarkably shrinked end part of the resin tube 3, the projections 12 are fitted to the grooves 9 of the holding member 5, both stopper tools are connected, and the end of the resin tube 3 is held between both stopper tools 4 to be fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller having a sponge rubber whose peripheral surface is covered with a tube, and more particularly to a roller tube fixing method suitable for use as a transfer roller of an electrophotographic printer.

[0002]

2. Description of the Related Art FIG. 22 is a schematic side view of an image forming unit using a conventional transfer roller. In the figure, reference numeral 31 denotes the entire image forming unit, and reference numeral 32 denotes a chassis in which main parts are arranged. A photosensitive drum 33 serving as a toner support is installed on the chassis 32 together with a driving unit (not shown) for rotating the photosensitive drum 33 in the direction of arrow C.

[0003] Around the photosensitive drum 33, a charging roller 34 for charging the peripheral surface of the photosensitive drum 33, and an image light for irradiating the charged peripheral surface with image light to form an electrostatic latent image. LED array head 35, toner 37 on electrostatic latent image
Are arranged in order.

The developing roller 38 forms a part of the developing device 36. The developing device 36 further stores a toner 37 therein and has a toner cartridge 3 set in the chassis 32.
9. Toner storage unit 40 containing toner 37, toner 3
Supply roller 39 for supplying the toner 7 to the developing roller 38, and the developing roller 38
And a blade 40 to be provided on the peripheral surface.

Further, a transfer roller 41 and a cleaning roller 45 are disposed downstream of the developing roller 38. The transfer roller 41 has a metal shaft 2 serving as a rotation shaft rotatably held by a bearing 43, and the bearing 43 is further attached to the chassis 32 via a spring 44. As a result, the peripheral surface of the transfer roller 41 is in contact with the peripheral surface of the photosensitive drum 33 by receiving a predetermined pressing force from the spring 44.

The operation of the entire image forming unit in the above configuration will be described. When the photosensitive drum 33 is driven to rotate at a constant speed in the direction of arrow C by a driving unit (not shown), charges are simultaneously applied by the charging roller 34 and the peripheral surface thereof is uniformly charged.

When image light is radiated on the charged photosensitive drum 33 by the LED array head 35, the portion irradiated with the image light by the photoconductive photosensitive element is discharged, and the portion between the portion irradiated with the image light and the portion not irradiated with the image light is discharged. Causes a potential difference, thereby forming an electrostatic latent image.

The electrostatic latent image reaches a position facing the developing roller 38 of the developing device 36 by further rotating the photosensitive drum 33 in the direction of arrow C. Here, the toner 37 charged to the same polarity as the charged potential on the surface of the photosensitive drum 33 is used.
Adhere to the electrostatic latent image of the portion irradiated with the image light by Coulomb force, and this is visualized.

At this time, the transfer roller 41 is
It rotates in the direction of arrow D at the same peripheral speed as that described above. However, as described above, the contact portion between the roller 41 and the drum 33 is kept in a pressure-contact state by receiving the urging force of the spring 44, so that sufficient contact therebetween can be maintained. I have.

On the other hand, a recording paper 46, which is a recording medium supplied by a paper feeding means (not shown), is conveyed between the photosensitive drum 33 and the transfer roller 41 in synchronization with the rotation of the photosensitive drum 33. That is, when the leading end of the recording paper 46 reaches the junction between the photosensitive drum 33 and the transfer roller 41, the recording paper 46 is transported in the direction of the arrow E while being sandwiched between them, and comes into contact with the electrostatic latent image on the photosensitive drum 33. However, at this time, the timing is adjusted so that a desired position of the recording paper is in contact with the recording paper.

The transfer roller 41 applies a charge having a polarity opposite to that of the toner 37 to the back surface of the recording paper 46 when the recording paper 46 is transported. Therefore, when the recording paper 46 comes into contact with the electrostatic latent image on the photosensitive drum 33, the toner 37 attached to the electrostatic latent image is attracted to the charge of the opposite polarity, whereby the toner image on the photosensitive drum 33 is Transferred onto 46.

Thereafter, the recording paper 46 provided with the toner image
Is pressed and heated by a fixing device (not shown) to fix the toner image, thereby completing a series of printing operations.

Here, the transfer roller 4 conventionally used
1 and a method of manufacturing the same will be described with reference to FIGS.

As shown in FIG. 23, the transfer roller 41
Around the metal shaft 2, a foamed and sponge-like cylindrical semi-conductive sponge rubber 6 is attached, and the outer periphery thereof is further covered with a resin tube 51 of semi-conductive fluorine or nylon. I have. These resin tubes 51 have heat shrinkability in many cases, and are in close contact with the sponge rubber 6, and the resin tube 51 is bonded to the sponge rubber 6 with an adhesive 52.

Next, a manufacturing process of the transfer roller 41 will be described with reference to FIGS. First, as shown in FIG. 24, a kneaded rubber 53 before vulcanization is wound around a metal shaft 2 with a predetermined thickness.

From this state, by foaming, vulcanizing, and further cooling under predetermined conditions such as temperature, the kneaded rubber 53 is stabilized with an increase in volume as shown in FIG. Thereafter, as shown in FIG. 26, the workpiece is finished by grinding with a grindstone 54 so that its outer diameter becomes a predetermined dimension. Foaming,
The vulcanized kneaded rubber 53 is referred to as sponge rubber 6.

Next, as shown in FIGS. 27 and 28, the adhesive 52 spouted from the nozzle 53 is uniformly applied to the peripheral surface of the sponge rubber 6 which has been ground, and then slightly smaller than the outer diameter of the sponge rubber 6. A large resin tube 51 is placed over this.

At this stage, since there is a gap between the sponge rubber 6 and the resin tube 51 and the adhesive 52 which does not harden at room temperature is used, these are not yet integrated. This state is placed in a heating furnace (not shown) and heated at a predetermined temperature for a predetermined time.

As a result, the resin tube 51 starts to contract, and conversely, the sponge rubber 6 starts to expand. Here, the state change at this time will be described in order. First, the resin tube 51 having a small heat capacity and being exposed to hot air starts to contract, and the sponge rubber 6 contained therein is tightened from the outside. Thereafter, the expansion of the sponge rubber 6 starts, and both are in a state of being stretched.

Then, the curing of the adhesive 52 between them starts, and in this state, the resin tube 51 and the sponge rubber 6 are integrated. Thus, the transfer roller 41 as shown in FIG. 23 is completed.

[0021]

When the transfer roller 41 is formed as described above, in consideration of productivity, as many transfer rollers as possible are put in a heating furnace and heat treatment is performed. It is desirable to complete the transfer roller 41.

However, in such a situation, the above-mentioned shrinkage and expansion also vary due to variations in the temperature in the furnace and variations in hot air depending on the location. If the timing of curing of the adhesive 52 further varies under such conditions, the adhesive hardens before reaching the original outer diameter convergence point determined by the contraction of the resin tube 51 and the elastic force of the sponge rubber 6. As a result, it is difficult to make the outer diameter of the transfer roller 41 uniform at the time of completion, and the yield is reduced.

[0023]

A rotating shaft of a roller used as at least one of a pair of rollers capable of transferring a member to be clamped by rotating at substantially the same peripheral speed in a state where the peripheral surfaces are pressed against each other. Around this, a sponge rubber material is formed with a predetermined length in the axial direction of the rotating shaft and a predetermined thickness in the radial direction, and a heat-shrinkable tube is covered so as to include the sponge rubber material. Heat shrink and fix both ends of the tube near both ends of the sponge rubber material.

As a fixing method at this time, a pair of fixing means that can be fitted are arranged at both ends of the sponge rubber material,
The end of the tube is clamped by the fixing means.

As another fixing method, disk-shaped stoppers are arranged at both ends of the sponge rubber material, and the ends of the tube are brought into close contact with the peripheral surface of the stopper at the stage of the heat shrinkage. Then, the stopper and the tube are fixed with an adhesive tape.

As another fixing method, the tube and the sponge rubber material are fixed by attaching C-rings to both peripheral surfaces of the sponge rubber material after the heat shrinkage.

[0027]

FIG. 1 is a perspective view of a transfer roller 1 according to a first embodiment of the present invention, and FIG. 2 is a cross section including the center of a metal shaft 2 at one end thereof. It is sectional drawing. 3 to 5 are cross-sectional views for explaining a manufacturing process at the same portion as the cross-section in FIG.

In this case, as shown in FIG.
The resin tube 3 is not bonded to the sponge rubber 6 contained therein by an adhesive, but is fixed at both ends by a holding member 5 and a stopper 4.

The structure and the manufacturing process will be described in more detail. As shown in FIG. 3, a sponge rubber 6 is wound around the metal shaft 2 with a predetermined thickness. The process of forming this is shown in FIGS.
The description is omitted because it is the same as the manufacturing process shown in FIG.

Next, as shown in FIG. 3, the holding member 5 is press-fitted from both ends of the metal shaft 2 and is fixed to the end of the sponge rubber 6 in close contact therewith. As shown in FIG. 6 which is a perspective view of the holding member 5, the whole holding member 5 has a substantially disk shape.
A press-fitting hole 7 for fitting with the shaft 2 is formed at the center, a surface facing the sponge rubber 6 is a flat surface, and a concave portion 8 is formed on the opposite surface to which a convex portion of a stopper 4 described later fits. I have.

Further, a groove 9 is formed at a predetermined position on the inner peripheral surface of the concave portion for fitting a projection formed on the distal end peripheral surface of the convex portion of the stopper 4 described later.

Next, in this state, the heat-shrinkable resin tube 3
At this time, the length of the resin tube 3 at both ends in the axial direction is set to be longer by a predetermined length than the length of the sponge rubber 6 plus the holding member 5 as shown in FIG. I do.

Next, this is put into a heating furnace as in the prior art,
The resin tube 3 is caused to undergo thermal contraction, and is brought into close contact with the sponge rubber 6. At this time, as shown in FIG. 5, the resin tube 3 in the holding member 5 at both ends is largely contracted in a portion without receiving.

Thereafter, the stopper 4 is moved in the direction of arrow A so as to sandwich the end of the greatly contracted resin tube 3 and is pressed into the holding member 5. As shown in FIG. 7 which is a perspective view of the stopper 4, the whole stopper 4 has a substantially disk shape.
A central hole 10 that loosely fits into the metal shaft 2 is formed in the center portion, a convex portion 11 that fits into the concave portion 8 of the holding member is formed on a surface facing the holding member 5, and a distal end peripheral surface thereof is formed. Is formed with a projection 12 that fits into the groove 9 of the holding member.

Accordingly, when the stopper 4 is pressed into the holding member 5 as described above, the projection of the stopper is fitted into the recess of the holding member while sandwiching the greatly contracted end of the resin tube 3, and eventually, as shown in FIG. As shown, the protrusion 12 is fitted into the groove 9 of the stopper, and the two stoppers are connected, and the end of the resin tube 3 is sandwiched and fixed between the two stoppers.

Since these operations are performed at both ends of the sponge rubber 6 as shown in FIG.
It is fixed with a certain degree of tension in the axial direction, and sufficient strength can be obtained against stress, twisting, and skidding (displacement in the axial direction) when mounting the printer.
Incidentally, the surface of the holding member B, which is in contact with the resin tube, may be roughened in order to increase the frictional force and strengthen the fixing force.

FIG. 8 is a perspective view of a transfer roller 15 showing a second embodiment of the present invention, and FIG. 9 is a cross-sectional view showing a cross section including the center of the metal shaft 2 at one end thereof. is there. 10 to 12 are cross-sectional views for explaining a manufacturing process at the same portion as the cross-section in FIG.

Also in this case, the resin tube 16 of the transfer roller 15 is not adhered to the sponge rubber 6 contained therein by an adhesive as shown in FIG. 9, but is fixed at both ends by a stopper 17 and an adhesive tape 18. Have been.

The structure and manufacturing steps will be described in more detail. As shown in FIG. 10, a sponge rubber 6 is wound around the metal shaft 2 with a predetermined thickness.
The process for forming this is the same as the manufacturing process shown in FIGS. 24 to 26 described in the conventional example, so that the description is omitted.

Next, as shown in FIG.
The stopper 17 is press-fitted from both ends of the sponge rubber 6, and is fixed to the end of the sponge rubber 6 in close contact. This stopper has a disk shape as a whole, but has a press-fit hole 18 formed in the center thereof, and the outer diameter is set slightly smaller than the outer diameter of the sponge rubber 6.

Next, the resin tube 16 is put on the sponge rubber 6 in this state. At this time, at both ends, the length of the resin tube 16 in the axial direction is reduced by the stopper 17 on the sponge rubber 6 as shown in FIG. It is set so as to be longer by a predetermined length than the added length.

Next, this is put into a heating furnace as in the prior art,
The sponge rubber 6 is made to shrink by heat of the resin tube 16.
In close contact. At this time, the resin tubes 16 at the stoppers 17 at both ends are connected to the stoppers 1 as shown in FIG.
7 so as to be in close contact with the peripheral surface. Thereafter, the resin tube 16 is cut at a substantially middle portion of the thickness of the stopper 17 shown by a dotted line in FIG.

Thereafter, as shown in FIGS. 8 and 9, respectively,
In order to fix the ends of the resin tube 16 to the peripheral surface of the stopper 17, an adhesive tape 18 is wound so as to cover them together. At this time, the outer diameter of the fixed end portion is the sponge rubber 6.
Consideration is made so that the outer diameter does not become larger than the outer diameter of the roller portion that covers the roller.

In the case of the second embodiment, the resin tube does not have a fixing force as much as the first embodiment. However, since the resin tube is simpler and the cost can be easily reduced, the transfer roller is less stressed in the mounted state. It is suitable for low-speed machines that do not add noise.

FIG. 13 is a perspective view of a transfer roller 22 according to a third embodiment of the present invention, and FIG. 14 is a sectional view showing a cross section including the center of the metal shaft 2 at one end thereof. is there. FIGS. 15 to 17 are views for explaining the manufacturing process at the same portion as the cross section of FIG.

Also in this case, as shown in FIG. 14, the resin tube 23 of the transfer roller 22 is
4 are fixed to the sponge rubber 24 by retaining rings 25 at both ends without being bonded to the sponge rubber 4 by an adhesive.

The structure and manufacturing process will be further described. As shown in FIG. 15, a sponge rubber 24 is wound around the metal shaft 2 with a predetermined thickness. The main process for forming the sponge rubber 24 is shown in FIGS.
The description is omitted because it is the same as the manufacturing process shown in FIG.

However, in this embodiment, since the resin tube is fixed to the sponge rubber 24 itself, the axial length of the sponge rubber 24 should be increased accordingly so that no inconvenience occurs in the mounting state. Must be set.

Further, as shown in each figure, a fixing groove 26 is formed in the sponge rubber 24 on the peripheral surface near both ends. Then, the resin tube 23 is put on the sponge rubber 24. At this time, the length of the resin tube 23 in the axial direction is set to be substantially equal to the length of the sponge rubber 24 as shown in FIG.

Next, this is put into a heating furnace as in the prior art,
The heat shrinkage of the resin tube 23 is performed so that the sponge rubber 2
Adhere to 4. At this time, the resin tubes 23 in the fixing grooves 26 at both ends contract as shown in FIG. 17 so as to be in close contact with the inner walls of the fixing grooves.

Thereafter, as shown in FIG.
Is mounted with a retaining ring 25 made of resin and having one opening. The retaining ring 25 is generally called a C-ring and has appropriate elasticity, and fixes the resin tube 23 to the sponge rubber 24 by tightening it with an appropriate force. FIG. 3 shows a state in which the open portion is expanded.

In the case of the third embodiment, although the structure is simple and advantageous in cost, the diameter near the end of the transfer roller at the time of finishing is set to a desired value by the tightening force of the retaining ring 25. It has the following further advantages:

That is, generally, when a transfer roller is pressed against a photosensitive drum in a printer, both ends of a metal shaft are often used as bearings. For this reason, the transfer roller
It bends like a beam subjected to a distributed load of point support, especially at the center of the roller.

FIGS. 19 and 20 show the photosensitive drum 33 at this time.
FIG. 7 is a diagram for explaining a contact area of a conventional transfer roller 41 with respect to FIG. 19, the transfer roller 41 has both ends of the metal shaft 2 held by the bearings 43 shown in FIG. 22 as described above, and receives a predetermined pressing force to contact the peripheral surface of the photosensitive drum 33. The rollers rotate at substantially the same peripheral speed.

FIG. 20 shows the state of contact between the two rollers at this time, and is a perspective view seen in the direction of arrow B from the rotation axis L1 of the photosensitive drum 33 to the rotation axis L2 of the transfer roller 41. The contact portion 27 of the roller is indicated by oblique lines.

As is apparent from FIG.
The contact area becomes larger toward both ends of the recording paper 1, so that the charge density of the charge applied by the transfer roller to the recording paper 46 shown in FIG. It will be difficult.

Therefore, conventionally, a method of tapering the end portion of the transfer roller to keep the contact area uniform has been considered. On the other hand, in the third embodiment, the diameter in the vicinity of the transfer roller end can be set to a desired value by the tightening strength of the retaining ring 25 as described above. As described above, the shrinkage of the sponge rubber increases as it approaches the retaining ring 25, so that the sponge rubber can be formed into a shape substantially similar to that of the sponge rubber tapered.

As described above, in the case of the third embodiment, the contact area can be kept uniform as described above. Suitable for high-end printers that focus on quality.

FIG. 21 shows the transfer roller at the time of finishing in the case where the sponge rubber and the resin tube are bonded with an adhesive as in the prior art, and in the case of the first embodiment according to the present invention where the bonding is not performed. 9 is a histogram showing the comparison of the variation in the outer diameter.

In the graph, the vertical axis indicates the number of occurrences, and the horizontal axis indicates that the manufacturing error is positive when the manufacturing error is larger than the target value, and negative when the manufacturing error is smaller than the target value, and is proportional to the size. Shown by numerical values. In addition, the bar-shaped indicators in the case where they are not bonded are indicated by diagonal lines.

As is apparent from the histogram, the variation is reduced and the rate of finishing with high accuracy is increased when no bonding is performed.

In the above embodiment, the present invention has been described by taking the transfer roller of the electrophotographic printer as an example. However, the present invention is not limited to this, and may be used for a developing roller, for example. In addition, the present invention can be used for the surface processing of a rubber platen used in almost all serial impact printers.

[0063]

As described above, according to the present invention, since the sponge rubber of the transfer roller and the resin tube are not bonded, the outer diameter of the transfer roller is uniquely determined by the elastic force of the sponge rubber and the contraction force of the resin tube. And the outside diameter accuracy is greatly improved by eliminating the factors of variation.

In addition, when the manufacturing process for fixing the resin tube using the stopper and the retaining ring is compared with the bonding process having the conventional adhesive application equipment, the cost, safety, environment, etc. are significantly different. Significant improvement can be expected.

When the resin tube deteriorates due to long use, it has conventionally been necessary to replace the transfer roller itself. However, since the resin tube alone can be easily replaced, the metal shaft and sponge rubber can be continuously used. Can be used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a transfer roller according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the transfer roller according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the first embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the first embodiment of the present invention.

FIG. 5 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the first embodiment of the present invention.

FIG. 6 is a perspective view of the holding member 5 of FIG. 1;

FIG. 7 is a perspective view of the stopper 4 of FIG. 1;

FIG. 8 is a perspective view showing a transfer roller according to a second embodiment of the present invention.

FIG. 9 is a sectional view of a transfer roller according to a second embodiment of the present invention.

FIG. 10 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the second embodiment of the present invention.

FIG. 11 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the second embodiment of the present invention.

FIG. 12 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the second embodiment of the present invention.

FIG. 13 is a perspective view showing a transfer roller according to a third embodiment of the present invention.

FIG. 14 is a sectional view of a transfer roller according to a third embodiment of the present invention.

FIG. 15 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the third embodiment of the present invention.

FIG. 16 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the third embodiment of the present invention.

FIG. 17 is a partial cross-sectional view of a transfer roller in one step of manufacturing according to the third embodiment of the present invention.

FIG. 18 is a diagram for explaining a change in the outer diameter according to the third embodiment of the present invention;

FIG. 19 is a diagram showing a contact area of a transfer roller with respect to a conventional photosensitive drum.

FIG. 20 is a diagram illustrating a contact area of a transfer roller with respect to a conventional photosensitive drum.

FIG. 21 is a histogram showing variations in finished dimensions of the transfer roller according to the conventional and the first embodiment.

FIG. 22 is a schematic side view of an image forming unit using a conventional transfer roller.

FIG. 23 is a sectional view showing a configuration of a conventional transfer roller.

FIG. 24 is a diagram showing one process of manufacturing a conventional transfer roller.

FIG. 25 is a diagram showing one process of manufacturing a conventional transfer roller.

FIG. 26 is a diagram showing one process of manufacturing a conventional transfer roller.

FIG. 27 is a diagram showing one process of manufacturing a conventional transfer roller.

FIG. 28 is a diagram showing one process of manufacturing a conventional transfer roller.

[Explanation of symbols]

1 transfer roller, 2 metal shaft, 3 resin tube, 4 stopper, 5 holding member, 6 sponge rubber, 15 transfer roller, 16 resin tube, 1
7 stopper, 18 adhesive tape, 22 transfer roller, 23 resin tube, 24 sponge rubber,
25 retaining ring, 33 photosensitive drum, 41 transfer roller, 44 spring, 46 recording paper

Continued on the front page F term (reference) 2H032 AA05 BA08 BA19 3J103 AA02 AA14 AA23 AA51 AA74 BA41 FA15 GA02 GA58 GA74 HA04 HA12 HA18

Claims (4)

[Claims] 1. A heat-shrinkable material having a predetermined length in the axial direction of the roller and a sponge rubber material formed in a predetermined thickness in the radial direction around the rotation axis of the roller. A tube fixing method for a roller, wherein a tube is covered and thermally contracted, and both ends of the tube are fixed near both ends of the sponge rubber material. 2. A method of fixing both ends of the tube by disposing a pair of fixing means that can be fitted at both ends of the sponge rubber material and clamping the ends of the tube by the fixing means. The method for fixing a tube of a roller according to claim 1, wherein: 3. A disk-shaped stopper is disposed at both ends of the sponge rubber material, and is formed such that an end of the tube is in close contact with a peripheral surface of the stopper at the stage of the heat shrinkage. 2. The roller tube fixing method according to claim 1, wherein both ends of the tube are fixed by fixing the stopper and the tube with an adhesive tape. 4. After the heat shrinking, both ends of the tube are fixed by attaching C-rings to peripheral surfaces of both ends of the sponge rubber material and fixing the tube and the sponge rubber material. The method for fixing a tube of a roller according to claim 1, wherein: