JP2008094050A - Rubber roll manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a rubber roll having small unevenness of electric characteristic in a circumferential direction by preventing a weld line from generating when a rubber material is gathered in a head without depending on formulation of the rubber material. <P>SOLUTION: This invention has the following constitution. That is, this invention is a manufacturing method of the rubber roll which coats the rubber material on the outer periphery of a core by a rubber extruding machine having a cross head. More particularly, the cross head is constituted by a die and a mandrel. This invention has a feature of forming the rubber roll through a step of extruding the rubber material along a spiral groove (1) directed in an outlet direction provided on the inner wall of the die. The above manufacturing method is characterized to perform the step of extruding the rubber material along a spiral groove (2) directed in the outlet direction provided on the outer wall of the mandrel which constitutes the cross head. The manufacturing method is characterized that the spiral groove (1) and the spiral groove (2) are directed in reverse rotational directions to one another. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a rubber roll used for a paper feed roll, a charging roll, a transfer roll, a developing roll, a toner supply roll, a cleaning roll, etc. incorporated in a copying machine or a printer.

  In a method for manufacturing a rubber roll using a general crosshead extruder, a molding method in which a rubber material is coated while a core metal is passed through a crosshead die is manufactured by the following manufacturing method, for example.

  In the uniaxial rubber extruder 1 shown in FIG. 1, the cored bar and the rubber whose position is determined in advance by the cored bar guide 5 are bonded to a substantially central part where the rubber is extruded in a cylindrical shape in the extruder head 2. The core metal a coated with the adhesive is fed by the core metal feed roll 4.

  Thereby, the rubber material b supplied to the outer periphery of the core metal is integrally covered in the core metal-rubber adhesion area.

  The core-rubber columnar integral c extruded from the die 6 at the tip of the extruder head through the coating area is separated to the length of each roll by a take-off cutting machine attached to the extruder.

  In this extrusion molding, the rubber flow path flows from the extruder 1 to the head, and then is divided into two hands so as to wrap the core bar guide 5 and flows along the core bar guide and the head inner wall (outer wall of the flow path). Meeting again face-to-face to create a flow in the direction of the die 6 (FIGS. 1 and 2).

  When this rubber is associated, particularly in the case of a rubber material having a high viscosity, a so-called weld line 7 is generated in which the associated surfaces are not sufficiently fused and project from the die while having a boundary surface (FIG. 3).

  Even when the surface is ground, the weld line is often formed even inside, and greatly affects the electrical resistance unevenness and surface hardness after molding on the rubber roll.

  Further, depending on the composition of the rubber material, when the extrusion process is performed in parallel with the longitudinal direction of the rubber roll, the molecular arrangement of the rubber material formed at the time of extrusion has a history characterized in the longitudinal direction.

  This causes a variation in the electric characteristics of the molded rubber roll in the circumferential rotation direction, and if the roll has functions such as charging, transfer, and development, a functional defect such as a horizontal streak defect of an image occurs.

  For the previous issues, it may be possible to deal with the problems such as lowering the viscosity of the rubber material prescription and lowering the rubber fraction. Considering extrudability in a formulated formulation will increase the development load of the formulation study.

  Further, in order to solve the problems described later, a resistance control layer is provided on the outer layer of the rubber roll, or an expensive ion conductive material with little resistance variation due to dispersion has been used.

  Accordingly, the present invention provides a method for producing a rubber roll that prevents weld lines generated when rubber materials meet in a head regardless of the rubber material prescription and has less circumferential unevenness in electrical characteristics.

  In order to solve the above problems, the present invention has the following configuration. That is, a rubber roll manufacturing method for coating a rubber material on the outer periphery of a metal core with a rubber extruder having a crosshead has the following configuration and steps.

  Specifically, the crosshead is constituted by a die and a mandrel, and is formed through a process in which the rubber material is extruded along a spiral groove (1) provided in the inner wall of the die toward the outlet. It is characterized by that.

  In the manufacturing method, the rubber material is extruded along a spiral groove (2) provided in an outer wall of a mandrel constituting the cross head and directed toward an outlet.

  In the above manufacturing method, the spiral groove (1) and the spiral groove (2) are spiral grooves in opposite directions of rotation.

  It is possible to generate an effective turbulent flow in the rubber flow path where the rubber materials meet in the cross head and flow toward the die die.

  As a result, it is possible to prevent a weld line generated when the rubber material meets in the head regardless of the rubber material prescription, and to form a rubber roll with less circumferential unevenness in electrical characteristics.

  Hereinafter, the present invention will be described in detail with reference to FIGS.

  In the present invention, a molding process for coating the rubber material on the outer periphery of the core metal by a rubber extruder by a crosshead die method is performed as follows.

  That is, extrusion is performed with a die inner wall corresponding to the outer wall of a rubber flow path that narrows toward the die in a taper shape of a head that integrally covers the core metal and the rubber material (FIG. 4).

  Preferably, a mandrel that is provided in the head and that supplies the cored bar is provided with a spiral groove (FIG. 5).

  More preferably, a crosshead having a structure (FIG. 6) in which the spiral groove provided on the mandrel and the spiral groove provided on the inner wall of the die are reversely rotated with each other is used.

  In this case, the rubber rolls are molded while rotating in directions opposite to each other with respect to the flow direction while both the spiral grooves convey the rubber material toward the die die.

  The flow of the rubber material extruded by the screw rotation of the extruder enters the head and is divided into two by the mandrel guide.

  The bisected rubber flow wraps around the core metal guide and meets on the opposite side of 180 ° with the core metal guide interposed therebetween. At the same time, the rubber material advances in the die direction.

  The associated rubber material surfaces flow along the mandrel and die inner wall in the direction of the die die.

  According to the present invention, the rotational flow of the rubber material generated by the spiral groove of the die with respect to the flow direction and the spiral groove of the mandrel that generates a flow opposite to the flow of the rotation cause the rubber assembly interface and the die die. A turbulent flow occurs in the flow of the rubber material in the process toward

  As a result, the association interface is kneaded and disappears, and the rubber roll having no weld line is extruded. A molecular arrangement including a complex rotation is formed in the flow history of the rubber roll extruded at the same time.

  This is not only the disappearance of the weld line, but also the resistance unevenness in the circumferential rotation direction is alleviated in the electrical characteristics of the rubber roll, and a good rubber roll can be manufactured.

  Examples of the present invention will be specifically described below.

  In the cross-head extruder head configuration, a spiral groove processed so as to be clockwise when the rubber material flows toward the die die along the inner wall was used (FIG. 4).

  In the mandrel for supplying the core metal, a spiral groove processed so as to be counterclockwise when the rubber material flows toward the die die along the mandrel was used (FIG. 5). FIG. 6 is a schematic diagram of both structures superimposed on each other.

  The extruder is a uniaxial vent type extruder with a φ60mm screw and is equipped with the crosshead type cored bar and rubber coating function. Made.

  The rubber material charged into the single screw vent extruder was continuously supplied with NBR as the main polymer and kneaded with carbon black, plasticizer, filler, vulcanization accelerator, and vulcanizing agent.

  The rubber material sent to the head from the extruder passes through the coating area with the core through the flow by the internal structure of the head, and is formed into a roll shape in a state of being integrally coated from the extruder base.

  At this time, the rubber flows clockwise toward the die in the vicinity of the mandrel, and counterclockwise toward the die in the vicinity of the inner wall of the die.

  Extruded rubber rolls do not have a weld line, and rolls that have been molded through the vulcanization process can also be obtained with a roller having little abnormal hardness and uneven electrical resistance in the circumferential direction. Thereafter, the roll is supplied for surface treatment by coating or shape formation by polishing.

The schematic of the rubber roll manufacturing apparatus using the crosshead extruder. FIG. Rubber roll with weld line Die with spiral groove in clockwise direction Mandrel with spiral groove counterclockwise Combination of the above die and mandrel

Explanation of symbols

1 Single screw vent extruder (uniaxial rubber extruder)
2 Crosshead (die)
3 Screw 4 Core metal supply roll 5 Mandrel 6 Cap die 7 Weld line AB Section a Adhesive metal core b Rubber compound c Rubber coated roll after extrusion

Claims (3)

  In a method of manufacturing a rubber roll in which a rubber material is coated on the outer periphery of a core metal by a rubber extruder having a cross head, the cross head is composed of a die and a mandrel, and is directed toward an outlet provided on the inner wall of the die. A method for producing a rubber roll, wherein the rubber material is formed through a process in which the rubber material is extruded along the spiral groove (1).   The method for producing a rubber roll according to claim 1, wherein the rubber material is extruded along a spiral groove (2) provided in an outer wall of a mandrel constituting the cross head and directed toward an outlet.   3. The method for producing a rubber roll according to claim 2, wherein the spiral groove (1) and the spiral groove (2) are spiral grooves in directions opposite to each other.

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