JP2017056623A - Manufacturing method of roll and manufacturing method of charging roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in an outer diameter of a rubber material at both ends of a core grid in an axial direction when an extra rubber material at both ends is cut compared to a structure in which a feeding speed of the core grid is not changed from a speed controlled in a quadratic curve at a planned cut position in a method for manufacturing a roll by feeding the core grid while extruding the rubber material.SOLUTION: Through feeding at a speed controlled in a quadratic curve a core grid 22 to a center part C of a rubber material G extruded in a cylindrical shape, an outer peripheral surface of the core grid 22 is covered by the rubber material G, and the rubber material G at both ends of the core grid 22 in an axial direction is cut. Note here that the feeding speed of the core grid 22 is increased temporarily to a level higher than the speed controlled in the quadratic curve at a planned cutting position P2 where the rubber material G is cut.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a roll manufacturing method and a charging roll manufacturing method.

  The roll manufacturing method of Patent Document 1 is a method of changing the supply speed of the core metal shaft in the longitudinal direction of one rubber roll by using an extruder into a crown shape. Is increased from the front end to the center of the core bar and decreased from the center to the rear end.

JP 2008-52025 A

  In the method of manufacturing a roll by feeding a metal core while extruding a rubber material, excess rubber material at both ends is cut to expose the metal core at both axial ends of the roll. Here, when the rubber material is cut, the residual stress of the rubber material is released, so that the outer diameter of the rubber material at both ends of the core metal may be increased from a predetermined outer diameter.

  The present invention relates to a method of manufacturing a roll by feeding a metal core while extruding a rubber material, compared to a configuration in which the feed speed of the metal core is not changed from a quadratic curve-controlled speed at a planned cutting position. An object is to suppress an increase in the outer diameter of the rubber material at both ends when the excess rubber material at both ends in the axial direction is cut.

  In the roll manufacturing method according to claim 1 of the present invention, the outer peripheral surface of the metal core is made of the rubber material by feeding the metal core to the central portion of the rubber material extruded in a cylindrical shape at a speed controlled by a quadratic curve. A roll manufacturing method for covering and cutting a rubber material at both axial ends of the core metal, wherein the feeding speed of the core metal is controlled by the quadratic curve at a planned cutting position where the rubber material is cut. Increase temporarily over the speed.

  In the roll manufacturing method according to claim 2 of the present invention, the outer diameter of the rubber material when the feeding speed at the planned cutting position is the first speed V1 is the set outer diameter of the rubber material at the planned cutting position. Δd1 is larger than the second speed V2 among the feeding speeds, the outer diameter of the rubber material at the axial center position of the cored bar, and the rubber material at the planned cutting position. The difference from the outer diameter is the outer diameter difference Δd2, and the feeding speed at the scheduled cutting position is the third speed V3 obtained by V3 = V1 + {(V1−V2) / Δd2} × Δd1.

  According to a third aspect of the present invention, there is provided a method for producing a charging roll according to the first or second aspect, wherein an elastic layer made of the conductive rubber material is formed on the core metal.

  The invention of claim 1 is a method of manufacturing a roll by feeding a metal core while extruding a rubber material, compared to a configuration in which the feed speed of the metal core is not changed from the quadratic curve-controlled speed at the planned cutting position. It is possible to suppress an increase in the outer diameter of the rubber material at both ends when the excess rubber material at both ends in the axial direction of the core metal is cut.

  Invention of Claim 2 suppresses that the outer diameter of a rubber material increases at the both ends of a metal core compared with the structure which does not make the feeding speed of the metal core in the scheduled cutting position the 3rd speed V3mm / s. Can do.

  According to the invention of claim 3, the outer diameter of the conductive elastic layer is increased at both ends of the core metal as compared with the configuration in which the feeding speed of the core metal is not changed from the speed controlled by the quadratic curve at the planned cutting position. Can be suppressed.

It is sectional drawing which shows the structure of the roll manufacturing apparatus which concerns on this embodiment. It is a block diagram of the control part concerning this embodiment. (A) It is a schematic diagram of the metal core which concerns on this embodiment. (B) It is sectional drawing of the rubber roll part which concerns on this embodiment. (C) It is a schematic diagram of the charging roll which concerns on this embodiment. It is a graph which shows the change with respect to the position of the axial direction of the feeding speed of the metal core which concerns on this embodiment. (A), (B) It is explanatory drawing which shows the state which the metal core which concerns on this embodiment is sent in and taken out from the rubber material. (A), (B) It is explanatory drawing which shows the state by which the rubber material of the edge part of the rubber roll part which concerns on this embodiment is cut | disconnected. (A) It is explanatory drawing which shows the state which is pressing the charging roll which concerns on this embodiment on the photoreceptor. (B) It is explanatory drawing which shows the state which is pressing the charging roll which concerns on a comparative example against a photoconductor. It is a table | surface which shows the amount evaluation result of the charging roll of Examples 1 and 2 of this embodiment and Comparative Examples 1, 2, 3, 4, 5, 6, and 7. (A), (B) It is explanatory drawing which shows the state by which the rubber material of the edge part of the rubber roll part which concerns on a comparative example is cut | disconnected.

  An example of a roll manufacturing method and a charging roll manufacturing method according to the present embodiment will be described. The rubber-coated shaft body manufactured by the roll manufacturing method and the charging roll manufacturing method according to the present embodiment is used as the charging roll 70 (see FIG. 3C) as an example.

  The charging roll 70 shown in FIG. 3C is an example of a roll, and rotates in contact with the photosensitive member 92 (see FIG. 7A) of the image forming apparatus to charge the outer peripheral surface of the photosensitive member 92. It is. In addition, the charging roll 70 includes a metal cored bar 22 and an elastic layer 72 made of a conductive rubber material G coated on the outer peripheral surface of the cored bar 22. Further, as an example, the charging roll 70 has an outer diameter of the rubber material G at a central position in the axial direction of the cored bar 22 larger than an outer diameter of the rubber material G at both axial positions. It is made into a shape.

[Roll manufacturing equipment]
FIG. 1 shows a roll manufacturing apparatus 10 as an example of the present embodiment. The roll manufacturing apparatus 10 includes a discharge unit 12 that discharges the rubber material G and the cored bar 22, an extraction unit 16 that is disposed below the discharge unit 12 and extracts a rubber roll unit 56 that will be described later, and the discharge unit 12 and the extraction unit 16. And a pressing portion 14 that presses the rubber material G. In the following description, the front (lower) cored bar 22 may be referred to as a cored bar 22A, and the rear (upper) cored bar 22 may be referred to as a cored bar 22B. In the case where the front core metal 22A and the rear core metal 22B are not distinguished, the core metal 22 will be described.

[Discharge part]
The discharge unit 12 is constituted by a so-called cross head die. The discharge unit 12 includes a supply unit 18 that supplies the unvulcanized rubber material G, an extrusion unit 20 that extrudes the rubber material G supplied from the supply unit 18 in a cylindrical shape, and a cylindrical shape that is extruded from the extrusion unit 20. And a feeding portion 24 that feeds the cored bar 22 at an interval from the central portion C of the rubber material G.

<Supply section>
The supply unit 18 is provided with a screw 28 rotatably inside a cylindrical main body 26 extending in the illustrated horizontal direction. The screw 28 is rotationally driven by a supply motor 30 with the illustrated lateral direction as an axial direction. The operation of the supply motor 30 is controlled by a control unit 80 described later. In addition, on the supply motor 30 side of the main body portion 26, a charging port 32 for charging the rubber material G is provided. Thereby, the rubber material G introduced from the insertion port 32 is supplied toward the extrusion unit 20 while being kneaded by the screw 28 inside the main body 26. In the supply unit 18, the supply speed of the rubber material G is adjusted by adjusting the rotation speed of the screw 28.

(Rubber material)
The rubber material G contains a rubber material, a processing aid, a conductive agent, a plasticizer, a vulcanization accelerator, and the like. In the present embodiment, epichlorohydrin rubber is used as an example of the rubber material, and carbon black is used as an example of the conductive agent.

  The rubber material is not limited to epichlorohydrin rubber, but isoprene rubber, chloroprene rubber, butyl rubber, polyurethane, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin- Examples include ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and blend rubbers thereof. Among these, polyurethane, silicone rubber, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and blended rubbers thereof are preferably used. These rubber materials may be foamed or non-foamed.

  As the conductive agent, an electronic conductive agent or an ionic conductive agent is used. Examples of electronic conductive agents include carbon blacks such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide And various conductive metal oxides such as tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution; and the like.

  Examples of the ionic conductive agent include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium, perchlorates and chlorates of alkaline earth metals, and the like.

  These conductive agents may be used alone or in combination of two or more. There is no restriction | limiting in particular in the addition amount of a electrically conductive agent. In the case of an electronic conductive agent, it is preferably in the range of 1 to 40 parts by mass, more preferably in the range of 10 to 30 parts by mass with respect to 100 parts by mass of the rubber material. More preferably, it is in the range of 15 to 25 parts by mass. In the case of an ionic conductive agent, the range is preferably 0.1 parts by weight or more and 5.0 parts by weight or less, and 0.5 parts by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of the rubber material. It is more preferable that Thus, the rubber material G has high conductivity.

<Extruded part>
The extrusion unit 20 includes a cylindrical case 34 connected to the supply unit 18, a columnar mandrel 36 disposed at the center of the case 34, and a discharge head 38 disposed below the mandrel 36. ing.

  The mandrel 36 is held by a holding member 40 attached to the upper side of the case 34. The discharge head 38 is held by a holding member 42 attached to the lower side of the case 34. The rubber material G flows in an annular shape (cylindrical shape) between the outer peripheral surface of the mandrel 36 (the outer peripheral surface of the holding member 40) and the inner peripheral surface of the holding member 42 (the inner peripheral surface of the discharge head 38). An annular channel 44 is formed.

  Further, an insertion hole 46 into which the cored bar 22 is inserted is formed in the center of the mandrel 36 with the vertical direction shown in the figure as the axial direction. Furthermore, the lower part of the mandrel 36 has a tapered shape toward the lower end. A lower region below the mandrel 36 is a joining portion 48 where the core metal 22 supplied from the insertion hole 46 and the rubber material G supplied from the annular flow path 44 merge. That is, in the extruding part 20, the rubber material G is extruded in a cylindrical shape toward the joining part 48, and the cored bar 22 is fed into the central part C of the rubber material G that is extruded in a cylindrical shape.

  Here, the rubber material G flows through the merging portion 48 and is extruded from the extruding portion 20 without the cored bar 22. The speed at this time is referred to as an extrusion speed. That is, the extrusion speed is the speed of the rubber material G (substantially constant speed) when the rubber material G is pushed out of the discharge head 38 by the rotation of the screw 28 without the cored bar 22.

<Sending part>
The feeding unit 24 has a roll pair 50 disposed above the mandrel 36. A plurality of roll pairs 50 (three pairs as an example) are provided, and one roll of each roll pair 50 is rotated by a driving roll 54 via a belt 52. The drive roll 54 is configured such that a rotation speed (feeding speed described later) is controlled by a control unit 80 described later.

  Specifically, the drive roll 54 is rotationally driven by the drive motor 84. The operation of the drive motor 84 is controlled by the motor driver 82. Further, the operation of the motor driver 82 is controlled by the control unit 80. As a result, when the drive roll 54 is driven by the drive motor 84, the cored bar 22 sandwiched by each pair of rolls 50 is sent toward the insertion hole 46 of the mandrel 36.

<Control unit>
As shown in FIG. 2, the control unit 80 includes a computer. And the roll manufacturing program for making a computer function as an example of a control means is set to the control part 80. FIG.

  Specifically, the control unit 80 includes a CPU (Central Processing Unit) 80A, a ROM (Read Only Memory) 80B, a RAM (Random Access Memory) 80C, and a nonvolatile memory 80D. The control unit 80 has a configuration in which a CPU 80A, a ROM 80B, a RAM 80C, a nonvolatile memory 80D, and an input / output interface (I / O) 80E are connected to each other via a bus 80F.

  A motor driver 82 is electrically connected to the input / output interface 80E, and the motor driver 82 is electrically connected to the drive motor 84. In this case, for example, a roll manufacturing program is written in the ROM 80B and is read by the CPU 80A, whereby the CPU 80A controls the motor driver 82. The non-volatile memory 80D may be connected to the outside of the control unit 80 via the input / output interface 80E, and may be an external storage device such as a memory card, for example.

  Further, the control unit 80 shown in FIG. 1 controls the decrease and increase in the speed at which the core bar 22 is fed into the rubber material G by the feeding section 24 (hereinafter referred to as the feeding speed). As an example, the feeding speed of the core bar 22 by the feeding section 24 is set to be higher than the extrusion speed of the rubber material G and the extraction speed of the rubber roll section 56 by the extraction section 16 described later.

  The total length of the cored bar 22 is set to a predetermined length L (see FIG. 3A). Here, the rear core metal 22B sent by the roll pair 50 pushes the front core metal 22A existing in the insertion hole 46 of the mandrel 36, and the front core metal 22A is taken out by the extraction portion 16. It is. For this reason, the plurality of metal cores 22 are sequentially moved in the insertion hole 46.

  Further, the driving of the drive roll 54 is temporarily stopped when the front end (lower end) of each cored bar 22 is positioned at the front end (lower end) of the mandrel 36. On the other hand, even when the drive roll 54 is temporarily stopped, the rubber material G continues to be pushed out. For this reason, the cored bar 22 is fed at an interval in the junction 48 below the mandrel 36.

  As described above, in the discharge unit 12, the rubber material G is pushed out in a cylindrical shape at the merging portion 48, and a plurality of core bars whose speeds are controlled by a quadratic curve, which will be described later, are spaced from the central portion C of the rubber material G. 22 are sequentially sent. As a result, the cored bar 22 exists in the central part C of the rubber material G between the rubber roll 56 in which the outer peripheral surface of the cored bar 22 is covered with the rubber material G, and the front cored bar 22 and the rear cored bar 22. The hollow portions 58 as an example of the intermediate portion not to be discharged are alternately discharged from the discharge head 38. Note that a primer (not shown) is applied in advance to the outer peripheral surface of the cored bar 22 in order to improve the adhesiveness with the rubber material G.

  As shown in FIG. 3B, the rubber roll portion 56 is formed by covering the outer peripheral surface of the cored bar 22 and the end surfaces 68 at both axial ends of the cored bar 22 with the rubber material G. The charging roll 70 is a state in which the rubber material G at both axial ends of the rubber roll portion 56 is cut along the radial direction of the cored bar 22 and both ends of the cored bar 22 are exposed (see FIG. 3C). It is.

<Pressing part>
As shown in FIG. 1, the pressing portion 14 has a pair of semi-cylindrical pressing members 60. The pair of pressing members 60 are disposed to face each other so as to sandwich the rubber roll portion 56 discharged from the discharge portion 12. Each pressing member 60 is formed with a protruding portion 62 that protrudes toward the rubber roll portion 56. Each pressing member 60 is movable in the horizontal direction and vertical direction shown in the figure by a drive mechanism (not shown). The pair of pressing members 60 presses the hollow portion 58 that is a part of the rubber material G without the core metal 22 between the front core metal 22A and the rear core metal 22B, so that the rubber material G is cut off.

<Extraction department>
The extraction part 16 has a pair of semi-cylindrical extraction members 64. The pair of extraction members 64 are disposed to face each other so as to sandwich the rubber roll portion 56 discharged from the discharge portion 12. Each extraction member 64 is formed with a grip portion 66 having a shape corresponding to the outer peripheral surface shape of the rubber roll portion 56. Each extraction member 64 can be moved in the horizontal direction and the vertical direction in the figure by a drive mechanism (not shown). The speed at which the rubber roll portion 56 is taken out (pulled out) by the take-out member 64 is referred to as the take-out speed.

  As shown in FIG. 7A, the charging roll 70 is rotated while being pressed against the rotating photosensitive member 92. At this time, if the contact width (nip width) between the charging roll 70 and the photosensitive member 92 is not uniform in the axial direction, the electric field strength becomes non-uniform in the axial direction, which may cause uneven charging. As a method of aligning the nip width, it is known that the outer shape of the charging roll is a crown shape (a shape in which the outer diameter at the center in the axial direction is larger than the outer diameter at both ends). As a manufacturing method of the crown-shaped charging roll 70, there is a quadratic curve control method for controlling the feeding speed of the cored bar 22 with a quadratic curve.

[Comparative Example]
9A shows a rubber roll portion 202 of a comparative example, and FIG. 9B shows a charging roll 200 of a comparative example. The rubber roll portion 202 has a core metal 22 and a rubber material G, and is formed by controlling the feeding speed of the core metal 22 with a quadratic curve. The charging roll 200 is obtained by cutting both end portions in the axial direction of the rubber roll unit 202. Here, in the production of the charging roll 200, when the rubber roll portion 202 is molded only by quadratic curve control, and the rubber roll portion 202 is vulcanized to cut off the excess rubber material G at the axial end, the rubber material G The residual stress may be released, and the honey portion 204 may be formed at the end. The honey portion 204 means an enlarged diameter portion that protrudes radially outward from the outer diameter determined by the charging roll 200.

  As shown in FIG. 7B, in the charging roll 200 of the comparative example, when the outer peripheral surface of the charging roll 200 is pressed against the outer peripheral surface of the photosensitive member 92 with the splash portion 204 remaining, a depression near the splash portion 204 is formed. It becomes difficult for the part to come into contact with the photosensitive member 92. For this reason, the pressing force F2 in this recessed part becomes smaller than the pressing force F3 in another part. Thus, when the photosensitive member 92 is charged using the charging roll 200 of the comparative example, the potential of the outer peripheral surface of the photosensitive member 92 facing the depressed portion does not reach the predetermined potential, and the recording medium (not shown) There is a possibility that the amount of toner decreases and an image density difference (density unevenness) with other parts occurs.

(Setting of sending speed)
Next, the setting of the feeding speed of the cored bar 22 in the control unit 80 will be described.

  As a method for suppressing the occurrence of the splash portion 204 of the comparative example, the outer diameter of the planned cutting position of the rubber material G where the residual stress of the rubber material G is released can be mentioned in advance. In other words, if the feeding speed of the cored bar 22 is increased from the speed of the quadratic curve control at the planned cutting position of the rubber material G, it is considered that the formation of the threaded portion of the rubber material G is suppressed.

  FIG. 4 shows a feeding speed set at each axial position of the cored bar 22 (see FIG. 3A) in the present embodiment as a graph G1. The position P0 is the tip position of the cored bar 22, and the feeding speed at the position P0 is Vg. The position P1 is a start position at which acceleration is started with respect to the speed of the quadratic curve control (graph G2 indicated by a two-dot chain line), and the feed speed at the position P1 becomes the feed speed Vd by the quadratic curve control. ing. The position P2 is a planned cutting position of the cored bar 22 corresponding to the position where the excess rubber material G (see FIG. 6B) is cut, and the feeding speed at the position P2 is Ve. The position P3 is an end position where the acceleration is finished with respect to the speed of the quadratic curve control (returns to the quadratic curve control), and the feeding speed at the position P3 becomes the feeding speed Vb by the quadratic curve control. Yes.

  The position P4 is a position where the feeding speed of the cored bar 22 is the lowest, and the feeding speed at the position P4 is Va. The position P4 where the feeding speed is lowest is not the center position in the axial direction of the cored bar 22 due to the characteristics of the rubber material G (see FIG. 3C), but the completed charging roll 70 (see FIG. 3). (See (C)) corresponds to the axial center position of the cored bar 22 and the largest outer diameter. The position P5 is the rear end position of the cored bar 22, and the feeding speed at the position P5 is Vf. Here, the positions P1, P2, P3, P4, and P5 are arranged in this order from the front end in the axial direction of the cored bar 22.

  Let Vc be the feeding speed at the position P2 in the graph G2 for the quadratic curve control. Here, the height of the feeding speed of the cored bar 22 is, for example, Va <Vb <Vc <Vd <Ve <Vf <Vg. As described above, in the present embodiment, at the scheduled cutting position P2, the feeding speed Ve of the cored bar 22 is temporarily increased above the feeding speed Vc subjected to the quadratic curve control.

  Further, in this embodiment, an experiment is performed before the charging roll 70 (see FIG. 3C) is manufactured, and the feeding speed Ve is set. The feeding speed Ve is an example of the third speed V3. Specifically, by experiment, when the feeding speed at the planned cutting position P2 is the first speed V1 (= Vc) [mm / s], in the completed charging roll 70, the rubber material G at the planned cutting position P2 is obtained. Is larger by Δd1 [μm] than the set outer diameter. Δd1 [μm] is an outer diameter difference at the scheduled cutting position P2 of the charging roll 70. Moreover, the slowest speed among the feeding speeds is defined as the second speed V2 [mm / s], and the outer diameter of the rubber material G at the center position (the position where the outer diameter of the rubber material G is the largest) and the planned cutting position P2 It is assumed that the difference from the outer diameter of the rubber material G is an outer diameter difference Δd2 [μm]. Δd2 [μm] is the crown amount of the charging roll 70. The above-described feeding speed Va is an example of the second speed V2. As an example, the measurement of Δd1 and Δd2 was performed using a light-shielding type laser outer diameter measuring device (manufactured by Asaka Riken: ROLL2000).

  Here, in the present embodiment, the feeding speed Ve at the scheduled cutting position P2 is set as a third speed V3 [mm / s] obtained by Ve = V3 = V1 + {(V1−V2) / Δd2} × Δd1. ing. That is, since the outer diameter difference Δd2 [μm] of the rubber material G is caused by the difference between the first speed V1 and the second speed V2, in order to correct the outer diameter difference of 1 [μm], the feeding speed (V1−V2) / Δd2 [mm / s] is required. Thereby, in order to reduce (correct) the extra outer diameter difference Δd1 [μm] of the rubber material G, the feeding speed Ve = V3 = V1 + {(V1−V2) / Δd2} × Δd1 may be set.

[Action]
Next, the operation of this embodiment will be described.

  According to an example of the charging roll manufacturing method of the present embodiment, when the roll manufacturing apparatus 10 shown in FIG. 1 is activated, the supply motor 30 is driven. Thereby, the screw 28 is rotationally driven, and the unvulcanized rubber material G is extruded into a cylindrical shape at a predetermined extrusion speed.

  Subsequently, the drive motor 84 is driven, and the drive roll 54 and the roll pair 50 are rotated. As a result, as shown in FIG. 5A, the front cored bar 22A starts to be fed into the central portion C of the rubber material G at the feeding speed of the graph G1 (see FIG. 4). When the position from the tip of the core bar 22A (the length Lx from the lower end of the core bar 22 to the lower end of the mandrel 36) becomes P1 (see FIG. 4), the control unit 80 (see FIG. 1) In accordance with G1, the speed increase control of the feeding speed of the core metal 22A is started. In addition, although illustration is abbreviate | omitted, the front-end | tip (lower end) of the core metal 22A is covered with the rubber material G when the pressing member 60 (refer FIG. 1) moves to a horizontal direction.

  Subsequently, as shown in FIG. 4, when the position from the tip of the cored bar 22A (see FIG. 5A) becomes P2, the feeding speed is set to Ve. Specifically, the feeding speed of the cored bar 22 is increased from the position P1 to the position P2 according to the graph G1. Then, the feeding speed of the cored bar 22 is reduced from the position P2 to the position P3 according to the graph G1. From the position P3 to the position P5 via the position P4, the cored bar 22A is fed into the rubber material G at a feeding speed controlled by a quadratic curve. Thereby, as shown to FIG. 5 (B), the crown-shaped rubber roll part 56 is formed.

  Subsequently, it is determined that one rubber roll portion 56 has been taken out by managing the elapsed time from the start of feeding the cored bar 22. Then, the rubber member G of the hollow portion 58 is pushed out by the pressing member 60 (see FIG. 1), so that the end surface 68 of the front core metal 22A and the end surface 68 of the rear core metal 22B are covered with the rubber material G. As for the rear core metal 22B, the feeding speed of the core metal 22 is controlled according to the graph G1 (see FIG. 4), similarly to the front core metal 22A. The obtained rubber roll part 56 becomes the charging roll 70 (refer FIG.3 (C)) by cut | disconnecting the rubber material G of both ends after the above-mentioned vulcanization process.

  Here, as shown in FIG. 6A, in the rubber roll portion 56, the outer diameter of the rubber material G at the scheduled cutting position P2 is cut by the speed increase control in the vicinity of the scheduled cutting position P2. It becomes smaller than the position on the center side in the axial direction from the planned position P2. Thereby, when the rubber material G is cut by a cutting device (not shown), even if the residual stress of the rubber material G in the vicinity of the planned cutting position P2 is released and the outer diameter G increases, the outer diameter of the rubber material G is increased. , The increase from the determined outer diameter is suppressed. In other words, compared to the above-described comparative example, the formation of a splash portion at the end portion 71 in the axial direction of the charging roll 70 is suppressed.

  Further, according to an example of the roll manufacturing method of the present embodiment, the feeding speed of the cored bar 22 at the scheduled cutting position P2 is controlled as the third speed V3. That is, using the first speed V1, the second speed V2, the outer diameter difference Δd1, and the crown amount Δd2 described above, the third speed V3 = V1 + {(V1−V2) / Δd2} × Δd1 at the planned cutting position P2. The core bar 22 is fed in. As a result, the accuracy of the outer diameter of the rubber material G obtained at the scheduled cutting position P2 with respect to the set outer diameter is increased as compared with the configuration in which the third speed V3 is not used. An increase in diameter is suppressed.

  Furthermore, according to an example of the manufacturing method of the charging roll of this embodiment, it is suppressed that the outer diameter of the rubber material G in the scheduled cutting position P2 increases from the determined outer diameter. For this reason, an increase in the outer diameter of the elastic layer 72 at both ends of the cored bar 22 is suppressed.

  Here, as shown in FIG. 7A, in the charging roll 70 of the present embodiment, no splash portion is formed at the end portion 71 in the axial direction. For this reason, when the outer peripheral surface of the charging roll 70 is pressed against the outer peripheral surface of the photosensitive member 92, the pressing force F1 acting on the contact portion between the charging roll 70 and the photosensitive member 92 is the charging roller 200 (see FIG. 7 (B)), the variation in the axial direction of the charging roll 70 is reduced. As a result, when the photosensitive member 92 is charged using the charging roll 70, the outer peripheral surface of the photosensitive member 92 is almost uniformly charged in the axial direction, so that there is a difference in the width direction of the developer amount on the recording medium. The image density difference (density unevenness) is suppressed.

<Evaluation of amount of charging roll>
The charging rolls 70 and 200 having different manufacturing conditions were manufactured by changing the feeding speed of the cored bar 22, and the amount of splash was evaluated. Note that the amount of honey refers to the difference (distance) between the ideal curve of the outer diameter of the rubber material G at the end position of the cored bar 22 and the tip of the honey part. It is not the distance from the outer peripheral surface of the cored bar 22 to the radially outer end of the rubber material G.

  The rubber material G was obtained by kneading a material containing epichlorohydrin rubber as a main component and blending a processing aid, carbon black, calcium carbonate, a plasticizer, a vulcanizing agent, and a vulcanization accelerator. The rubber material G had a Mooney viscosity of 50 according to JISK6300-1 (2001). Further, the cored bar 22 used in this evaluation is made of SUS (stainless steel) having L (full length) = 354.5 [mm] and an outer diameter φ8.0 [mm]. The extruder used is a Mitsuba Seisakusho φ60 [mm], a screw effective length L and a screw outer diameter D ratio (L / D) of 20, screw rotation speed 10 [rpm], die diameter Was 12.5 [mm] and the extrusion pressure was 23 [MPa].

  The unvulcanized rubber material G was extruded with an extruder and the feed rate control pattern was changed to continuously pass the cored bar 22 through the extruder. After that, charging is performed at 165 [° C.] in a 75 [min] hot air furnace for vulcanization, and a charging roll 70 in which an elastic layer 72 as a vulcanized rubber layer of the rubber material G is formed on the cored bar 22 (FIG. 3 ( C)) was obtained. The rubber material G at both ends of the vulcanized charging roll 70 was cut to expose the cored bar 22.

  Evaluation results shown in FIG. 8 were obtained for the charging roll 70 of Examples 1 and 2, which is an example of this embodiment, and the charging roll 200 of Comparative Examples 1, 2, 3, 4, 5, 6, and 7. . The feeding speed [mm / s] at the crown apex means the feeding speed Va (see FIG. 4). The average feeding speed [mm / s] at both ends of the crown means a speed obtained by averaging the feeding speed at the front end of the core metal 22 and the feeding speed at the rear end. The crown amount [μm] is the difference between the outer diameter of the rubber material G at the axial end of the cored bar 22 and the outer diameter of the rubber material G at the center in the axial direction. A desirable partial speed increase amount [mm / s] is an ideal speed for bringing the amount of splash close to 0 [μm]. The actual partial speed increase [mm / s] is the speed when the cored bar 22 is increased during the manufacture of the charging roll.

  The evaluation of the amount of honey is based on the approximate ideal curve of the shape of the crown, and the amount of honey and the amount of dent is ± 40 [μm] or less in rank A, exceeding ± 40 [μm] and ± 60 [μm] or less. Some were evaluated as Rank B, and those exceeding ± 60 [μm] were evaluated as Rank C. Examples 1 and 2 are examples in which the calculated partial acceleration amount is applied. Comparative Examples 1, 2, 4, and 5 are examples in which the acceleration is excessively increased with respect to the calculated partial acceleration amount. Examples 3 and 6 are examples in which the amount of acceleration is insufficient with respect to the calculated partial acceleration amount, and Comparative Example 7 is an example in which partial acceleration is not performed.

  Here, from the result of evaluation of the amount of honey shown in FIG. 8, it was confirmed that the evaluation of the amount of honey becomes rank A in Examples 1 and 2 which are examples of the present embodiment. Moreover, about Comparative Examples 1, 2, 3, 4, 5, 6, and 7, it was confirmed that the amount of splash evaluation becomes ranks B and C.

  In addition, this invention is not limited to said embodiment.

  The means for extruding the rubber material G is not limited to a screw shape, and may be a piston shape. Further, the feeding means for the cored bar 22 is not limited to the roll pair, and may be a moving member having a gripping portion. Furthermore, the take-out means of the rubber roll unit 56 is not limited to the one that grips and moves the rubber roll unit 56, but may be moved by a roll pair.

  The feed speed Ve at the planned cutting position P2 may not be the third speed V3 as long as the amount of splash is suppressed as compared with the comparative example.

  In the roll manufacturing apparatus 10, the charging roll 70 is separated by the hollow portion 58 by the pressing portion 14. However, after the rubber material of the hollow portion 58 is pressed inward by the pressing portion 14, another cutting member (not shown) is illustrated. You may comprise so that the charging roll 70 may be isolate | separated by (cutter).

  Although the rubber material G illustrated what used epichlorohydrin rubber, it is not restricted to this, You may use another rubber material. Further, in the charging roll 70, the entire end surface 68 of the cored bar 22 was covered with a rubber material G in the hollow part 58 in a bag-like shape. However, the present invention is not limited to this, and at least the peripheral part of the end surface 68 of the cored bar 22 is What is necessary is just to be covered with the rubber material G of the hollow part 58. FIG.

  A roll (finished product) obtained by the roll manufacturing method of the present embodiment is used in an image forming apparatus such as a copying machine or a printer. It may be used for a transfer roll or the like.

10 roll manufacturing equipment,
22 cored bar 70 charging roll (an example of a roll)
72 Elastic layer G Rubber material P2 Scheduled cutting position

Claims (3)

The outer peripheral surface of the core metal is covered with the rubber material by feeding the core metal to the central portion of the rubber material extruded in a cylindrical shape at a speed controlled by a quadratic curve, and the rubber material at both axial ends of the core metal A method of manufacturing a roll for cutting
A method for manufacturing a roll, wherein the feeding speed of the cored bar is temporarily increased from the speed controlled by the quadratic curve at a planned cutting position where the rubber material is cut. When the outer diameter of the rubber material when the feeding speed at the planned cutting position is the first speed V1 is larger than the set outer diameter of the rubber material at the planned cutting position by Δd1,
The slowest speed among the feeding speed is the second speed V2,
The difference between the outer diameter of the rubber material at the central position in the axial direction of the metal core and the outer diameter of the rubber material at the planned cutting position is defined as an outer diameter difference Δd2.
2. The roll manufacturing method according to claim 1, wherein the feeding speed at the scheduled cutting position is a third speed V <b> 3 obtained by V <b> 3 = V <b> 1 + {(V <b> 1 − V <b> 2) / Δd <b> 2} × Δd <b> 1. In the manufacturing method of the roll of Claim 1 or Claim 2,
A method for producing a charging roll, wherein an elastic layer made of the conductive rubber material is formed on the core metal.