JP2007210035A - Manufacturing method of rubber roll and rubber roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a rubber roll for obtaining a rubber roll, which achieves very short grinding time and excellent surface condition of a ground surface and has high-accuracy outside diameter run-out dimension when a wide grinding wheel is plunged into the outer peripheral surface of the rubber roll having an elastic layer of vulcanized rubber provided on the circumference on a core bar axis to perform grinding. <P>SOLUTION: In this manufacturing method of the rubber roll, the wide grinding wheel is plunged into the outer peripheral surface of the rubber roll having an elastic layer of vulcanized rubber provided on the circumference on the core bar axis to perform grinding. The method is characterized in that the wide grinding wheel is plunged in the radial direction of the rubber roll, and the wide grinding wheel is once backed off in the direction of separating from the rubber roll in the process of grinding, and after that, the wide grinding wheel is again plunged in the radial direction of the rubber roll to set grinding retraction, and the outer peripheral surface of the rubber roll is ground. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a manufacturing method for grinding an outer peripheral surface of a rubber roll such as a charging roll, a developing roll, and other various rolls used in an electrophotographic apparatus such as a copying machine, a laser beam printer, and a facsimile machine. In particular, the present invention relates to a method of manufacturing a rubber roll that makes it possible to obtain a rubber roll that has a very excellent surface property of a ground surface and has a very high outer diameter runout size while shortening the grinding time. Is.

  In recent years, colorization of electrophotography has progressed, and higher-level images such as higher definition and image uniformity (halftone uniformity) have been demanded. For this reason, an important factor for rubber rolls used in electrophotography is that the outer peripheral surface has few irregularities and is very excellent in surface properties. For example, in the charging roll, if there are large irregularities on the outer peripheral surface of the rubber roll, adhesion of toner and external additives increases. As this accumulates, the ability to charge the photosensitive drum is remarkably reduced and image defects occur. When the surface roughness Rz of a charging roll used in a typical monochrome LBP (laser beam printer) exceeds 10 μm, the above-mentioned image defect is likely to occur. On the other hand, when the surface roughness Rz of the charging roll used for the color LBP exceeds 6 μm, image defects are likely to occur.

  In addition, a rubber roll used for electrophotography is required to have high accuracy in outer diameter runout. For example, when the outer diameter fluctuation of the rubber roll is large in the charging roll, the variation in the width (referred to as the nip width) that contacts the photosensitive drum during one rotation of the charging roll increases. As a result, the amount of unevenness (referred to as circumferential unevenness) in which the photosensitive drum is charged during one rotation of the charging roll increases, and an image defect such as shading unevenness occurs on the printed image at the rotation pitch of the charging roll. The charging roll used in a general monochrome LBP tends to cause the above-described image defect when the outer diameter shake dimension exceeds 0.1 mm, whereas the charging roll used in the color LBP has an outer diameter fluctuation. If it exceeds 0.05 mm, an image defect tends to occur. Therefore, in the technology for producing a rubber roll used for electrophotography, it is necessary to achieve both high surface properties of the outer peripheral surface and high precision of the outer diameter runout dimension.

  One technique for manufacturing rubber rolls is grinding. Grinding is a process in which a rubber roll is rotated and a grindstone rotated at high speed is brought into contact therewith to finish the outer peripheral surface of the rubber roll into a predetermined shape and size. The rubber roll grinding machine has a mechanism that traverses the surface of the rubber roll to the left and right with a grinding wheel with a narrow width of about 30 mm to 50 mm and a grinding wheel with a width wider than the total length of the rubber roll. There is a mechanism that grinds in a lump. In the latter wide whetstone plunge grinding, the contact processing time between the grindstone and the rubber roll per unit time is remarkably increased, so that the grinding processing time can be greatly shortened. Therefore, recently, there is a tendency that a wide whetstone plunge grinding machine is generally used for grinding a rubber roll particularly used for electrophotography. Since grinding is performed by scraping rubber with a grindstone, the surface property of the rubber roll grinding surface tends to be inferior to the surface property of a rubber roll molded by a mold. Therefore, until now, grinding has been a technique mainly used for processing sponge-type rubber rolls and rubber rolls that do not require much surface properties.

  On the other hand, since electrophotography requires high functionality by a rubber roll in order to improve image quality, rubber materials used for the rubber roll are also diversifying. In particular, solid-type rubber rolls tend to be used more frequently than sponge-type rubber rolls for color high-quality electrophotography. Many solid-type rubber rolls have low grindability, such as silicone rubber and urethane rubber, which generate heat due to friction with the grinding wheel. Also, in the case of the rubber material, the grindability is significantly lowered when the blending ratio of the polymer is large and the blending ratio of the filler such as carbon black or calcium carbonate is small.

  The resistance during grinding of the rubber roll can be confirmed by the value of the load applied to the grinding wheel shaft motor. As the speed at which the wide grindstone is pressed against the rubber roll is increased, the force that the grindstone advances and pushes the rubber roll is greater than the force that the grindstone rotates and grinds the rubber roll, and the load on the grindstone shaft motor is very high. growing. In this state, the rubber roll is pressed and deflected in the opposite direction of the grindstone, and is not sufficiently ground, resulting in very poor grinding efficiency. This tendency is particularly noticeable with solid rubber materials and rubber materials with low grindability, and the speed of pressing the grinding wheel against the rubber roll cannot be increased, greatly reducing the grinding time. It becomes difficult.

  In order to solve the above problems, in order to prevent the load on the grinding wheel shaft motor from becoming too large when grinding a rubber roll with a wide grinding wheel, grinding is performed while gradually reducing the speed at which the wide grinding wheel is advanced. Thus, there is known a method (for example, see Patent Document 1) of obtaining a rubber roll excellent in surface properties of the ground surface and outer diameter runout accuracy while shortening the grinding time. The method of decelerating the forward speed of the wide grinding wheel in multiple stages aims to reduce the grinding load in stages.

  However, especially when grinding a solid type rubber roll or a rubber roll with reduced grindability on the compound surface with a wide grinding wheel plunge grinding machine, the speed at which the grinding wheel is pressed is affected by the fact that the rubber roll grinding resistance has greatly increased. Even when decelerating in multiple stages, the grinding load is reduced only slightly. For this reason, the effect of decelerating in multiple stages is poor, and it is very difficult to shorten the grinding time while maintaining or improving the surface properties of the grinding surface, which has been a major problem.

Japanese Patent Laid-Open No. 2004-195606

  Accordingly, the present invention has been conceived as a means for solving the above-described problems, and has a wide width on the outer peripheral surface of a rubber roll having an elastic layer of vulcanized rubber provided on a circumference on a core metal shaft. A method of manufacturing a rubber roll that performs grinding by plungeing a grindstone, and can obtain a rubber roll that has excellent surface properties on a ground surface and a high precision in outer diameter runout in a very short grinding time. A method for producing a rubber roll is provided.

  The above-described problem can be solved by the novel characteristic configuration means described below.

  That is, the present invention is a method for producing a rubber roll, in which a wide grindstone is plunge on the outer peripheral surface of a rubber roll having an elastic layer of vulcanized rubber provided on a circumference on a core metal shaft. Retraction is performed by causing the wide whetstone to plunge toward the radial direction of the rubber roll and then back off in the direction away from the rubber roll during grinding. Is set, and the outer peripheral surface of the rubber roll is ground.

  According to the method for manufacturing a rubber roll of the present invention, when retraction is set for the grindstone operation when a wide grindstone is plunge ground on a rubber roll having an elastic layer of vulcanized rubber provided on the circumference on the core metal shaft, The grinding roll improves the grinding efficiency by canceling the load applied to the grinding wheel shaft motor once and then plunge it again, the rubber roll has excellent surface properties in a very short grinding time, and the outer diameter runout dimension is highly accurate. Can be obtained.

  The method for producing a rubber roll of the present invention is preferable because the above-described effects can be greatly obtained particularly when producing solid type rubber rolls such as hydrin rubber, silicone rubber and urethane rubber. In addition to the above, the above-described effect is also significant when producing a rubber roll having a smooth surface or an electrophotographic rubber roll (for example, a charging roll or a developing roll) provided with a surface layer by coating the surface. Obtained and preferred.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows the relationship between the rubber roll grinding time and the rubber roll grinding allowance in the rubber roll manufacturing method of the present invention. The direction in which the grinding allowance of the rubber roll is reduced indicates that the wide grinding wheel is advanced in the radial direction of the rubber roll and plunge grinding is performed, and the direction in which the grinding margin of the rubber roll is increased is in the direction opposite to the radius of the rubber roll. Indicates that the vehicle is backed off and back off. FIG. 1 illustrates the case where the grinding allowance, which is the difference between the outer diameter of the rubber roll before grinding and the finished outer diameter after grinding, is 2 mm. According to the present invention, the above-described effects can be obtained when the outer diameter of the rubber roll after grinding is 6 to 20 mm, preferably 8 to 12 mm, and the grinding margin is 4 mm or less, preferably 2 mm or less. Is possible.

  The rubber roll manufacturing method of the present invention is set so as to perform grinding in five stages of rough grinding step 1, back-off grinding step 2, fine grinding step 3, fine grinding step 4 and spark grinding step 5.

  The rubber roll manufacturing method of the present invention will be described in more detail. The rubber roll is rotated at a predetermined rotational speed, and the wide grinding stone is advanced at a forward speed V1 in the radial direction of the rubber roll in the rough grinding step 1 to move the rubber roll. Grind the outer peripheral surface. Thereafter, a back-off grinding step 2 is set in which the wide grindstone is retreated at a retreat speed V2 in a direction away from the rubber roll. In the back-off grinding step 2, the wide whetstone is retracted and completely separated from the rubber roll, and then the wide whetstone is advanced again in the radial direction of the rubber roll at a forward speed V3 slower than the forward speed 1 to grind the outer peripheral surface of the rubber roll. Fine grinding step 3 is set. After the fine grinding step 3, step 4 is set in which the wide grindstone is advanced in the radial direction of the rubber roll at an advance speed 4 slower than the advance speed 3, and the outer peripheral surface of the rubber roll is ground. After the fine grinding step 4, a spark grinding step 5 is set in which the wide grindstone is brought into a spark state at a low position without moving forward and backward. After the spark grinding step 5, the grindstone is retracted in a direction away from the rubber roll at a high speed to stop the rotation of the rubber roll, and the rubber roll grinding process is completed.

  The rough grinding step 1 is a grinding step for increasing the grinding allowance of the rubber roll in as short a time as possible, and a very large load is applied to the grindstone shaft motor. The back-off grinding step 2 is a grinding step for canceling the load applied to the grinding wheel shaft motor in the rough grinding step 1 by retreating the wide grinding wheel once. The fine grinding step 3 is a grinding step in which the wide grindstone is backed off, and then the wide grindstone is again pressed against the outer peripheral surface of the rubber roll for grinding. The fine grinding step 4 is a grinding step for improving the surface property of the outer peripheral surface of the rubber roll. The spark grinding step 5 is a grinding step for finishing the surface property of the outer peripheral surface of the rubber roll without moving the wide grindstone forward and backward. If the surface property of the outer peripheral surface has already reached the target surface property at the time of the fine grinding step 4, the spark grinding step 5 may be omitted.

  If retraction is set for the operation of the wide grinding wheel, the load applied to the grinding wheel shaft motor is canceled once and then plunged again, so that the grinding wheel is ground more than the case where the load is continuously applied to the grinding wheel by changing the advance speed of the grinding wheel in multiple steps. Efficiency can be improved and grinding time can be shortened.

  If the timing of retracting the wide grindstone after the rough grinding step 1 is too early, useless time will be generated and the grinding time will be lengthened. If the timing of retracting the wide grindstone is too late, the wide grindstone and the rubber roll As a result, the grinding load becomes too large, and the grinding efficiency is lowered, resulting in a longer grinding time. For this reason, in the present invention, a method of setting the wide grindstone to retract at the moment when the load on the grindstone shaft reaches the maximum value is also possible. On the other hand, if the amount of retracting the wide grindstone in the back-off grinding step 2 is too large, a wasteful time that the rubber roll is not ground is generated, and the grinding time becomes long. Also, the amount of retracting the wide grindstone If the amount is too small, the grinding efficiency decreases and the grinding time becomes longer if the process shifts to the fine grinding step 3 while the grinding load of the wide grindstone and the rubber roll remains. For this reason, in the present invention, a method of setting the wide grindstone to advance again to the rubber roll at the moment when the load of the grindstone shaft motor becomes the load during idling is also possible. In this way, it is possible to eliminate useless grinding time by setting the timing for retreating and moving the wide grindstone with the load value of the grindstone shaft motor.

  FIG. 2 shows the relationship between the rubber roll grinding time and the rubber roll grinding allowance in the conventional rubber roll manufacturing method. As in FIG. 1, the direction in which the grinding allowance of the rubber roll is reduced indicates that the wide whetstone is advanced in the radial direction of the rubber roll to perform plunge grinding. FIG. 2 also illustrates the case where the grinding allowance, which is the difference between the outer diameter of the rubber roll before grinding and the finished outer diameter after grinding, is 2 mm.

  In the conventional method for manufacturing a rubber roll, the spark time is set after the speed of advancing the wide grindstone is changed in multiple stages and pressed against the outer peripheral surface of the rubber roll. FIG. 2 shows a typical example, and the grinding is performed in four stages of a rough grinding step 1, a fine grinding step 2, a fine grinding step 3, and a spark grinding step 4.

  FIG. 3 is an explanatory view of an apparatus for grinding the outer peripheral surface of the rubber roll in the rubber roll manufacturing method of the present invention. The left shaft surface of the metal core shaft 4 of the rubber roll 3 is clamped by the head stock side collet chuck 1 of the grinding device. On the other hand, the right shaft surface of the metal core shaft 4 is also clamped by the tail stock side collet chuck 9 of the grinding device. The tail stock side collet chuck 9 is moved forward in two stages with two cylinders, and the grip amount of the head stock side collet chuck 1 and the cored bar 4 is the same. The opposed head stock side collet chuck 1 and tail stock side collet chuck 9 are arranged so as to be able to grip the cored bar shaft 4 on the same axis. In this state, the head stock side rotating flange 2 to which the head stock side collet chuck 1 is attached has a mechanism that is rotated by the head stock side motor 6 at a predetermined rotational speed. Further, the tail stock side rotating flange 10 to which the tail stock side collet chuck 9 is attached is also a mechanism that is rotated by the tail stock side motor 11 at a predetermined rotational speed. The head stock side motor 6 and the tail stock side motor 11 rotate in synchronization with each other, and no twisting force acts on the core metal shaft 4.

  Grinding is performed by rotating the wide grindstone 5 wider than the entire length of the rubber roll 3 at a high speed while pressing the rubber roll 3 at a predetermined rotational speed and pressing the wide grindstone 5 against the rubber roll 3. The wide grindstone 5 is configured such that the grindstone shaft pulley 14 and the grindstone shaft motor pulley 13 rotate along the V belt 15. By displaying the value of the power consumption of the grindstone shaft motor 12 and taking the load value into the grinding program as the load applied to the grindstone shaft motor 12, it is possible to set the timing for moving the wide grindstone 5 forward and backward. It has become.

  Hereinafter, specific examples of the present invention will be described.

[Production method of rubber roll before grinding]
A closed kneading machine and a roll machine containing a rubber material containing 100 parts by mass of epichlorohydrin rubber, 10 parts by mass of plasticizer, 5 parts by mass of carbon black, 30 parts by mass of calcium carbonate, 2 parts by mass of sulfur, and 1 part by mass of mercaptobenzothiazole. Was used for kneading to obtain an unvulcanized rubber composition. The unvulcanized rubber composition is extruded with an extruder, and the core metal shaft is continuously passed through the crosshead die of the extruder, and the unvulcanized rubber composition is disposed on the outer periphery of the core metal shaft. After making it into a roll shape, it was placed in a hot air oven at 200 ° C. for 20 minutes for vulcanization to form a vulcanized rubber layer on the mandrel shaft to obtain a rubber roll before grinding.

[Rubber roll shape and grinding conditions]
Metal core shaft: total length 250mm, outer diameter φ6.0mm
Rubber roll: 230mm rubber surface length, outer diameter φ14.0mm, core metal shaft protrusion left and right 10mm
Rubber roll finish outer diameter: φ12.0mm
Grinding conditions: Wide grinding wheel plunge grinding
Wheel diameter Wheel width 235mm, φ200mm
Wheel rotation speed 2800rpm
Rubber roll rotation speed 300rpm

[Comparative Examples and Examples]
Example:
Rough grinding step 1 Advance speed 25mm / min, grinding wheel advance amount 0.85mm
Back-off grinding step 2 Retraction speed 300mm / min, Whetstone retraction amount 0.15mm
Fine grinding step 3 Advance speed 8mm / min, grinding wheel advance 0.25mm
Precision grinding step 4 Advance speed 0.4mm / min, grinding wheel advance amount 0.05mm
Spark grinding step 5 Spark time 3 seconds Grinding time 14.4 seconds

Comparative example:
Rough grinding step 1 Advance speed 15mm / min, grinding wheel advance 0.75mm
Fine grinding step 2 Advance speed 6mm / min, grinding wheel advance 0.2mm
Precision grinding step 3 Advance speed 0.1mm / min, grinding wheel advance amount 0.05mm
Spark grinding step 4 Spark time 3 seconds Grinding time 18.0 seconds

  The grinding wheel advance amount and the grinding wheel retraction amount are movement amounts in the radial direction of the rubber roll, and the margin of the outer diameter of the rubber roll to be ground is twice that amount.

  Table 1 shows the results of measuring the surface roughness Rz of the rubber rolls ground by the three manufacturing methods of the comparative example and the example. The average value of the surface roughness Rz of the rubber roll ground by the manufacturing method of the example is 3.95 μm, which is smaller than the average value of 5.04 μm of the surface roughness Rz of the rubber roll ground by the manufacturing method of the comparative example. There was a result that a rubber roll with excellent surface properties of the ground surface was obtained in a shorter grinding time.

  Table 2 shows the results of measuring the outer diameter runout of each of the 30 rolls ground by the manufacturing method of the comparative example and the example, and obtaining the maximum value, the average value, the minimum value, and the standard deviation. Show.

  The average value of the outer diameter runout of the rubber roll ground by the manufacturing method of the example is 0.018 mm, which is a value smaller than the average value 0.024 mm of the outer diameter runout of the rubber roll ground by the manufacturing method of the comparative example, As a result, a rubber roll excellent in dimensional accuracy of outer diameter runout was obtained in a shorter grinding time.

  The method for producing a rubber roll of the present invention comprises grinding a rubber roll having an elastic layer of vulcanized rubber provided on the circumference of a core metal shaft, particularly a rubber roll having an elastic layer made of hydrin rubber, NBR, EPDM, urethane rubber or the like. Thus, it can be suitably used for manufacturing.

In the rubber roll manufacturing method of this invention, it is explanatory drawing of the relationship between the grinding time at the time of grinding a rubber roll, and a grinding allowance. In the conventional rubber roll manufacturing method, it is explanatory drawing of the relationship between the grinding time at the time of grinding a rubber roll, and a grinding allowance. It is explanatory drawing of the apparatus which grinds the outer peripheral surface of a rubber roll in the manufacturing method of the rubber roll of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Headstock side collet chuck 2 Headstock side rotation flange 3 Rubber roll 4 Core metal shaft 5 Wide whetstone 6 Headstock side motor 7 Headstock stand 8 Tailstock stand 9 Tailstock side collet chuck 10 Tailstock rotation flange 11 Tailstock side motor 12 Grinding wheel shaft motor 13 Grinding wheel shaft motor pulley 14 Grinding wheel shaft pulley 15 V belt

Claims (4)

  A method of manufacturing a rubber roll, in which a wide grindstone is plunge on the outer peripheral surface of a rubber roll having an elastic layer of vulcanized rubber provided on a circumference on a core metal shaft, and the wide grindstone is ground with a radius of the rubber roll. Retraction in which the wide whetstone is once backed off in the direction away from the rubber roll during grinding by plunge toward the direction, and then the wide whetstone is plungeed again in the radial direction of the rubber roll for grinding. Is set, and the outer peripheral surface of the rubber roll is ground.   Rough grinding step 1 in which the wide grinding wheel is advanced to the maximum value of the load on the grinding wheel shaft motor at a forward speed V1 for plunging the rubber roll in the radial direction of the rubber roll, and the rough grinding step 1 sets the maximum load on the grinding wheel shaft motor. At the moment, the back-off grinding step 2 in which the wide grindstone is retracted at the retreating speed V2 in the direction away from the rubber roll, and the load of the grindstone shaft motor at the back-off grinding step 2 becomes the value at the time of no-load grinding. The fine grinding step 3 for advancing the wide grindstone in the radial direction of the rubber roll at an advancing speed V3 slower than the speed of the rough grinding step 1 at the moment, and the fine grinding step 3 after the fine grinding step 3 A fine grinding step 4 in which the rubber roll is advanced in the radial direction at a slower forward speed V4, and the width after the fine grinding step 4 Through grinding steps, including spark grinding step 5 to the grinding wheel to the spark condition, rubber roll method according to claim 1, characterized in that the grinding of the outer peripheral surface of the rubber roll.   A rubber roll used for electrophotography, wherein the rubber roll is produced by the method for producing a rubber roll according to claim 1 or 2.   The elastic layer of the vulcanized rubber provided on the circumference on the core metal shaft is a solid rubber, and the surface roughness after grinding of the outer peripheral surface of the rubber roll is Rz 6 μm or less, and on the outer peripheral surface of the rubber roll The rubber roll according to claim 3, wherein a surface layer is provided by performing a coating treatment.

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