JP2012014049A - Manufacturing method of elastic roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method in which a film thickness profile of an elastic roller can be exactly obtained even in a manufacturing method of the elastic roller in which the circumference of core-metals is covered with rubber mixtures different in their film thickness.SOLUTION: The manufacturing method of the elastic roller includes a step in which a plurality of core-metals each of which the circumference is covered with a layer of a rubber mixture are manufacture by supplying the plurality of core-metals serially and continuously to core-metal supply holes of a cross head, and also supplying the molten rubber mixture from an extruder connected to the cross head to the cross head. The outer diameter of the elastic roller is measured for every amount of movement of the core-metal sent into the cross head.

Description

  The present invention relates to a method for manufacturing an elastic roller used in an electrophotographic apparatus or the like.

  Usually, a charging roller, a paper feed roller, and the like used in a printer, a copier, and the like are often rotated by being brought into contact with a rotating photosensitive drum at a predetermined pressure. Since the charging roller or the like is pressed against the photosensitive drum or the like by pressing the core bar protruding from both ends of the roller, the core bar is bent by this pressing force. Therefore, the rubber strain (degree of compression) is different between the both end portions and the central portion of the rubber layer, and the nip area (referred to as the contact area per unit length) of the pressure contact portion with the photosensitive drum or the like is the both end portions. There is a problem that it is large and becomes small at the center. If the nip area is not uniform, for example, if it is a paper feed roller, circumferential speed unevenness will occur in the longitudinal direction, paper skew and wrinkles will occur, and when used as a charging roller, the electric field strength will be in the length direction of the roller. It may become non-uniform and uneven charging may occur, causing defects in the image.

  Conventionally, in order to make the nip area uniform, it is known that the rubber roller has a crown shape. After fully kneading the unvulcanized rubber composition at a predetermined temperature with an extruder, the unvulcanized rubber composition is extruded at a predetermined speed, and the outer periphery of the core metal is coated with a predetermined thickness by a crosshead die to form an unvulcanized rubber roller. This is vulcanized to obtain a charging roller or the like. As a method for forming a crown shape in the rubber roller, for example, there are the following methods (1) to (2) and the following method (3) described in the cited references 1 and 2. (1) A method in which the outer peripheral surface of the rubber roller is ground and polished into a crown shape by a polishing machine or the like after vulcanization. (2) A method in which an unvulcanized rubber roller is filled in a mold having a cavity that is previously molded into a crown shape, and the crown shape is formed simultaneously with vulcanization. (3) By changing the speed at which the mandrel is fed into the crosshead die or withdrawing speed by the extruder, the rubber layer coated on the outer circumference of the mandrel is changed in the length direction of the mandrel and simultaneously with the molding. A method of creating a crown shape (see Patent Documents 1 and 2).

  In addition, regarding an extrusion manufacturing method for an electric wire or an optical fiber using an extruder, Patent Document 3 discloses a method for controlling the outer diameter of an object to be extruded as follows. Measure the outer diameter of the extruded object with a uniform straight shape in the length direction at regular sampling time intervals, and control the extruder and take-out machine by measuring the outer diameter of the extruded object This is a method of controlling the outer diameter of the object to be extruded.

Japanese Patent Laid-Open No. 2003-300279 JP 2004-145012 A JP 2007-214042 A

  When the shape of the object to be extruded has a uniform straight shape as in the past, there is no problem even if the outer diameter of the object to be extruded is measured at a constant sampling time interval. However, in the case of an elastic roller having a crown shape whose outer diameter changes in the length direction of the core metal, the following error occurs in the method of measuring the outer diameter at a constant sampling time interval. FIG. 2 shows an enlarged schematic view of the exit portion of the crosshead die. As can be seen from FIG. 2, the core metal is covered with rubber in the die nozzle of the cross head. For example, when a crown-shaped elastic roller is formed by changing the thickness of the rubber layer to be coated, by changing the feed speed or take-up speed of the core bar to the cross head, This is achieved by varying the film thickness of the rubber mixture covering the periphery. That is, it is necessary to form the thickness of the rubber layer to be coated so that the outer diameter is large at the center of the elastic roller and the outer diameter gradually decreases toward both ends. For this reason, the outer diameter of the rubber layer is the same as the inner diameter of the die nozzle in the vicinity of the central portion where the outer diameter of the elastic roller is the largest, and the outer diameter of the rubber layer must be smaller than the diameter of the die nozzle toward both ends. As described above, the outer diameter of the rubber layer coated on the metal core in the die nozzle changes. However, the exact position where the rubber layer is coated on the metal core in this die nozzle is unobservable because it cannot be observed. Furthermore, as shown in FIG. 2, the outer diameter measuring device for measuring the outer diameter of the elastic roller must be installed outside the die nozzle because of its structure. Therefore, the position where the outer diameter is formed by coating the rubber layer in the die nozzle and the installation position of the outer diameter measuring device do not match due to structural problems. When an elastic roller is manufactured by continuously supplying a plurality of core bars to the crosshead die, the film thickness change of the rubber layer is repeated for each length of the core bars. Therefore, the moving speed of the metal core passing through the outer diameter measuring device is synchronized with the speed of movement of the metal core whose shape is coated in the die nozzle. Therefore, the moving speed of the metal core at the time of measuring the outer diameter of the elastic roller is different from the metal core speed at the time of forming the shape in the die nozzle. Therefore, for example, the following two problems have occurred.

First, the length of the core bar that passes through the outer diameter measuring device per unit time varies depending on the length direction of the core bar due to the change in the moving speed within one core bar. In the outer diameter measurement at the sampling time interval, a deviation occurs between the outer diameter measurement position and the length direction position of the core metal. Specifically, in order to create the rubber layer of the elastic roller in a crown shape, as described in Patent Document 1, molding is performed at a feed rate of the cored bar as shown in FIG. FIG. 3C shows an image of outer diameter measurement in the case of measurement at a constant sampling time interval Δt. Also,
As shown in FIG. 3C, when the end core metal moving speed is fast, a constant sampling time interval Δ
The moving distance Δx of the cored bar that passes through the outer diameter measuring instrument at t increases, and the moving distance Δx of the cored bar decreases as the moving speed of the cored bar gradually decreases toward the vicinity of the central part of the cored bar. Further, when the moving speed of the cored bar increases toward the other end, the cored bar moving distance Δx increases, resulting in an unequally spaced moving distance of the cored bar. Therefore, in order to measure the outer diameter with a constant movement distance of the core metal as shown in FIG. 3B, the sampling interval Δt has to be unequal as shown in FIG. 3D. For the above reasons, when the measurement axis is converted from the constant sampling interval Δt to Δx, Δx should be an unequal interval which is the actual moving distance. However, when the measurement axis is converted from the constant sampling interval Δt to the movement distance Δx of the metal core, the measurement axis is converted to an equal interval, that is, a movement distance different from the original movement distance. As a result, it is observed as a shape as indicated by a broken line in FIG.

Second, as described above, it was caused by the following factors (a) to (c). (A) An outer diameter measuring device is installed outside the die nozzle. (B) It is impossible to accurately grasp where the shape of the elastic roller is formed in the die nozzle. (C) Since the elastic roller is formed by continuously forming a plurality of cores, it passes through the outer diameter measuring instrument at a speed different from the original moving speed of the core. That is, when measuring the outer diameter of the elastic roller at a constant sampling time interval Δt,
The moving speed of the metal core when the outer diameter is measured is different from the moving speed of the metal core when the shape is formed. Therefore, it has been observed in a shape different from the shape to be originally measured by causing a deviation between the cycle of measuring the outer diameter and the cycle of the moving distance of the core metal passing through the outer diameter measuring instrument. Therefore, when measuring the outer diameter of an elastic roller molded into a crown shape at a constant sampling time interval as in the past, the length of the core bar that passes through the outer diameter measuring device per unit time is different. become. Furthermore, it passes through the outer diameter measuring device at a speed different from the original moving speed of the cored bar. Therefore, since the outer diameter of the elastic roller is not measured after grasping the moving distance of the cored bar, a measurement error occurs. For the reasons described above, the outer diameter profile of the elastic roller having a crown shape cannot obtain an accurate rubber film thickness profile of the elastic roller by measurement per unit time. That is, there is no step of calculating or measuring the moving distance of the cored bar.

  Therefore, by changing the feed rate or take-up speed of the core bar to the crosshead, a step of manufacturing a plurality of core bars each of which is coated with a rubber mixture layer for each of the core bars In the manufacturing method of the elastic roller including, this application aims at the following.

  An object of the invention according to the present application is to provide a method for manufacturing an elastic roller in which, in the elastic roller manufacturing method, an accurate shape can be obtained in the film thickness profile of the rubber layer in the length direction of each elastic roller during molding. There is to do.

In order to achieve the above object, the first invention according to the present application is to supply a plurality of core bars in series and continuously to a core bar supply hole of a cross head, and from an extruder connected to the cross head, A method for producing an elastic roller, comprising: supplying a molten rubber mixture to the crosshead to produce a plurality of core bars coated with a layer of the rubber mixture.
(1) changing the film thickness of the rubber mixture covering the periphery of each of the core bars by changing the feed rate or the take-up speed of the core bar to the crosshead;
(2) measuring the outer diameter of the core metal coated with the rubber mixture layer using an outer diameter measuring device provided at the outlet of the crosshead,
The step (2) is characterized in that the outer diameter is measured at every fixed movement distance of the cored bar.

  The second invention according to the present application is characterized in that, in the step (2) of the first invention, the movement distance of the metal core is detected by measuring the movement distance of the metal core itself.

  As described above, according to the present invention, as described above, the outer diameter of the elastic roller is measured by the outer diameter measuring instrument provided at the outlet of the crosshead with reference to the desired amount of movement of the metal core. Therefore, unlike the case where the outer diameter is measured at a predetermined sampling time interval, the film thickness profile in the length direction of the elastic roller can be obtained accurately. That is, even when the speed of the core metal changes, it is possible to suppress an error in the measurement position in the length direction of the elastic roller.

It is a schematic diagram of the extruder which can apply this invention. It is an enlarged view of the exit part of the crosshead die which can apply the present invention. It is a schematic diagram of the relationship between the core metal speed and the outer diameter for explaining the problem of the present invention. It is a schematic diagram of the outer diameter explaining the subject of this invention. It is a schematic diagram of the example explaining the means which detects the movement distance of the metal core which can apply this invention. It is a schematic diagram of the example explaining the means which detects the movement distance of the metal core which can apply this invention. It is a figure explaining the result of Example 1. FIG. It is explanatory drawing of the result of Example 2, 3 and the comparative example 1. FIG.

  Hereinafter, each invention will be described in more detail.

(Elastic roller)
In the present invention, the term “crown shape” refers to a shape in which the outer diameter of the rubber layer gradually increases from both ends in the length direction of the core metal toward the center portion. It also means that there is a portion where the diameter is constant along the length direction of the cored bar. The inverted crown shape refers to a shape (also referred to as a drum shape) in which the outer diameter of the rubber layer is gradually reduced from both ends in the length direction of the core bar toward the center.

(Method for producing elastic roller)
The manufacturing method of the elastic roller which concerns on the 1st aspect of this invention is demonstrated.

The manufacturing method of the elastic roller according to the present invention in which the periphery of the metal core is covered with a layer of a rubber mixture is a method using a cross head. Specifically, a plurality of metal cores are supplied in series and continuously to the metal core supply hole of the cross head, and a molten rubber mixture is supplied to the cross head from an extruder connected to the cross head. Manufactured by. And the characteristics of this invention have in the process of following (1) and (2).
(1) A step of varying the film thickness of the rubber mixture covering the periphery of each of the core bars by changing the feed rate or the take-up speed of the core bar to the cross head.
(2) A step of measuring the outer diameter of the cored bar covered with the rubber mixture layer by using an outer diameter measuring device provided at the outlet of the crosshead at every constant moving distance of the cored bar.
Furthermore, in the elastic roller manufacturing method according to the second aspect of the present invention, in the step (2), the outer diameter is measured by detecting the movement distance of the core metal by measuring the movement distance of the core metal itself. Including the step of:

(Method of manufacturing an elastic roller using a cross head)
A process of coating the unvulcanized rubber composition on the core bar by extruding an unvulcanized rubber composition prepared by mixing and kneading the rubber material and the additive together with the core bar will be described. FIG. 1 is an explanatory view schematically showing a method of manufacturing an elastic roller using a cross head. The extruder 1 includes a crosshead 2. To the cross head 2, a plurality of core bars 5 are serially and continuously supplied to the core bar supply holes of the cross head 2 by a core bar feed roller 3 rotating in the direction of arrow a. The unvulcanized rubber composition is supplied to the extruder 1 from the material charging port 6. The metal core 5 prepared in the metal core stocker 4 is continuously fed into the metal core supply hole by the metal core feed roller 3 whose feed rate can be adjusted. Then, a cylindrical unvulcanized rubber composition 7 is integrally extruded simultaneously with the core metal 5 inserted into the crosshead 2 so that the periphery of the core metal is covered with a layer of the unvulcanized rubber composition 7. A cored bar 5 is obtained. It is preferable that the trailing end of the preceding core bar is fed so that the leading end of the subsequent core bar always abuts. That is, by always abutting the rear end of the preceding metal core and the front end of the subsequent metal core, the unvulcanized rubber composition 7 does not enter between them, and the feed speed of the metal core 5 is stabilized. This is because the shape is also stabilized. Since the core metal is continuously supplied to the crosshead, the unvulcanized rubber layer continuously coated on the core metal 5 is continuously cut at the joint between the rear end of the preceding core metal and the front end of the subsequent core metal. A take-off step 8 is performed. Further, after the vulcanization step (not shown), the elastic roller is formed by cutting and removing the rubber layer at the end portion with a standard length.

  The material used as the core 5 of the elastic roller is preferably a stainless steel rod, a phosphor bronze rod, an aluminum rod, a heat-resistant resin rod or the like including a steel material such as a nickel-plated or chrome-plated SUM material. Is not to be done.

  Examples of the rubber material for forming the rubber layer used in the present invention include the following. Natural rubber, epicrawler hydrin rubber, butadiene rubber, styrene-butadiene rubber (SBR), nitrile rubber, nitrile butadiene rubber (NBR), ethylene-propylene rubber (EPDM), butyl rubber, chloroprene rubber (CR), silicone rubber, urethane rubber , Fluorine rubber, chlorine rubber, thermoplastic elastomer, etc. Any of these may be used alone or in a blended form.

In the rubber material, the conductivity can be set to a predetermined value by appropriately using a conductive agent. The electrical resistance of the rubber roller can be adjusted by appropriately selecting the type and amount of the conductive agent. Examples of conductive particles dispersed as a conductive agent in the rubber raw material are given below. Carbon black, graphite, particles of metal oxide (TiO ₂ , SnO ₂ , ZnO, etc.). Moreover, you may provide electroconductivity using a conductive polymer, an ionic conductive agent, etc. together with the said electroconductive particle. In addition, an inorganic or organic filler or a crosslinking agent may be added to the rubber raw material.

(Process 1)
For each of the core bars 5 continuously supplied to the cross head 2 by changing the feeding speed of the core bar 5 to the cross head 2 or the take-up speed of the core bar 5 covered with a rubber layer, The process of varying the film thickness of the rubber composition covering the periphery will be described. The amount of rubber (rubber layer thickness) covered on the core metal 5 by the cross head die 2 of the cross head extrusion device (referred to as a rubber roller molding device including the extruder 1 and the cross head die 2) is unvulcanized rubber. If the supply amount of the composition 7 is constant, it is inversely proportional to the moving speed of the metal core. When the moving speed of the metal core in the die nozzle 11 at the exit of the crosshead 2 is faster than the discharge speed of the unvulcanized rubber composition passing through the die nozzle, the unvulcanized rubber composition extruded into a cylindrical shape by the crosshead die The object moves while being covered while being stretched around the cored bar. Therefore, the thickness of the rubber layer is thinner than the die swelled thickness. That is, the thickness of the rubber layer can be adjusted to be thicker or thinner by adjusting the moving speed of the cored bar. The moving speed of the cored bar can be adjusted by changing the feeding speed of the cored bar to the cross head or by changing the take-up speed of the cored bar covered with the rubber layer.

  When the unvulcanized rubber composition is coated on the core metal 5 in a cylindrical shape using the crosshead die 2 in this way, the amount of unvulcanized rubber composition 7 extruded is constant and the moving speed of the core metal 5 is It changes with the site | part of the length direction of the metal core 5. FIG. By doing so, it is possible to manufacture an elastic roller in which the thickness of the unvulcanized rubber composition 7, that is, the cylindrical outer diameter is changed along the longitudinal direction by the lengthwise portion of the cored bar. By changing the moving speed of the cored bar 5 depending on the lengthwise portion of the cored bar, an elastic roller whose outer diameter profile is formed in a crown shape, an inverted crown shape, a tapered shape, a trapezoidal shape or the like is obtained. The feeding speed of the cored bar 5 is controlled by a feeding means (for example, the cored bar feeding roller 3) in which the predetermined speeds of the respective parts over the one end part, the central part and the other end part of the cored bar 5 are programmed in advance. Can do. Further, the take-up speed of the core bar can be similarly controlled by a take-up means programmed with a predetermined speed of each part over one end part, the central part and the other end part of the core bar 1. For example, FIG. 3A shows an example of the feeding speed of the core metal to the cross head when the elastic roller having the crown shape is produced by changing the feeding speed of the core metal 5. FIG. The horizontal axis indicates the length direction of the cored bar, and the vertical axis indicates the feed rate [mm / s] of the cored bar. As can be seen from FIG. 3 (a), in the case of the crown shape, the moving speed of the cored bar is increased at one end of the cored bar and is gradually decreased toward the central part, and further from the central part to the other end. The speed is gradually increased as it reaches the section. By changing the moving speed in this way, the film thickness of the unvulcanized rubber composition to be coated is thin at both ends and thick at the center, and a so-called crown-shaped rubber roller can be manufactured.

  In the above example, the case where the moving speed of the metal core 5 is changed while the discharge amount of the unvulcanized rubber composition 7 is constant has been described. In addition, the thickness of the rubber layer coated around the core metal 5 can also be changed by changing the discharge rate of the unvulcanized rubber composition 7 from the crosshead die 2 while keeping the moving speed of the core metal 5 constant. You can also adjust the height. Furthermore, in order to obtain a desired shape, it may be combined with a case where the feed rate or the take-up rate is changed.

(Process 2)
The process of measuring the outer diameter of the cored bar covered with the rubber mixture layer for each constant moving distance of the cored bar using an outer diameter measuring device provided at the outlet of the crosshead will be described.

(Measurement method of outer diameter)
As shown in FIG. 1, the outer diameter measuring device 9 for measuring the outer diameter of the roller is preferably installed in the die nozzle portion of the crosshead 2. As the outer diameter measuring device 9, various known displacement sensors, outer diameter measuring devices, and the like can be used. From the viewpoint of not scratching the surface of the unvulcanized rubber when measuring the outer diameter, it is preferable to use a laser or ultrasonic non-contact type outer diameter measuring instrument. For example, as the outer diameter measuring instrument 9 used in the present invention, LS-7500 and LS-7030M manufactured by Keyence Corporation can be used to measure the outer diameter of the elastic roller.

  In order to measure the outer diameter for each movement amount of the core metal, it is necessary to grasp the position in the length direction of the core metal extruded together with the rubber. As described in (Step 2) above, the moving speed of the cored bar changes the feeding speed of the cored bar to the cross head 2 or changes the take-up speed of the cored bar covered with a rubber layer. Can be adjusted. Therefore, the moving speed in the length direction of the core bar set in advance in a desired speed profile is known. Using this speed profile, the amount of movement of the desired metal core or the time for the position of the metal core is calculated in advance by the amount divided in the length direction of the metal core. When the outer diameter measurement positions are set at equal intervals in the length direction of the cored bar, the time interval at each position is not a fixed time because the moving speed in the length direction of the cored bar is different. Based on the time interval calculated in this way, the outer diameter of the elastic roller with the rubber layer coated around the core metal is measured by the outer diameter measuring device installed at the outlet of the crosshead. The outer diameter profile of the rubber layer in the length direction can be obtained. A larger number of divisions per cored bar is preferable because the outer diameter measurement point of the elastic roller is increased, and a more detailed outer diameter profile of the rubber layer of the elastic roller can be obtained.

  As a method for detecting the movement distance of the cored bar, the cored bar feed speed can be calculated in advance. For example, the rotation of the cored bar feed roller is programmed in advance so as to have a predetermined speed at each part over one end, the center and the other end of the cored bar in order to change the feed rate of the cored bar. This predetermined core metal speed is called a governing profile. A sampling time interval is calculated in advance from the speed control profile so as to be a predetermined movement distance of the cored bar. At this time, in order to make the elastic roller into a crown shape, the speed control profile of the cored bar increases in speed at one end of the cored bar and gradually decreases toward the central part and gradually toward the other end. Increases speed. Therefore, for example, in the case of a constant core metal movement distance, the measurement interval is short at one end, the measurement interval gradually increases toward the center, and the measurement interval gradually decreases toward the other end. Unequally spaced sampling. By periodically measuring the outer diameter of the elastic roller for each cored bar by this unequal interval sampling, the outer diameter of the elastic roller can be measured with a constant moving distance of the cored bar. A film thickness profile of the rubber layer of the elastic roller can be obtained.

  As other methods for detecting the amount of movement of the metal core, various known distance meters, displacement meters, tachometers, and the like can be used. For example, a case where a rotary encoder is installed so as to rotate in synchronization with a core metal feed roller will be described with reference to FIG. The rotation of the cored bar feed roller 3 is programmed in advance so as to have a predetermined speed at each part extending over one end, the center and the other end of the cored bar in order to change the feed rate of the cored bar. Therefore, the rotation speed is not constant. However, by detecting the rotation angle of the core metal feed roller by the rotary encoder, the amount of movement of the core metal can be detected indirectly from the radius and rotation angle of the feed roller. Each time a desired amount of movement of the metal core is detected, the outer diameter of the elastic roller at that time is measured by an outer diameter measuring device installed at the die outlet. The size of the rotary encoder is preferably equal to or smaller than that of the core metal feed roller so as not to hinder the rotation of the core metal feed roller. In the above example, the rotary encoder is installed so as to rotate in synchronization with the core metal feed roller. However, the roller that contacts and rotates the core metal separately from the core metal feed roller. It is good also as a system which installs and detects rotation of this roller with a rotary encoder.

  As another method for detecting the amount of movement of the mandrel, the mandrel can be directly detected using a distance detector or a distance meter to measure the amount of movement of the mandrel, and each time a desired amount of movement is detected. Alternatively, a method of measuring the outer diameter of the elastic roller may be used. Moreover, it is good also as a system which gives a marking to the metal core in advance at a desired interval and measures the outer diameter of the elastic roller each time this marking is detected. This will be described with reference to FIG. As can be seen from the figure, the cored bar is marked in advance, and the presence or absence of marking is detected by a separately installed marking detection sensor 14. By measuring the outer diameter of the roller based on the detection signal of the marking of the cored bar by the marking detection sensor 14, the outer diameter of the roller can be measured for each desired movement amount. Marking here refers to providing a different part from other parts, such as drawing a line with a paint, scoring a metal core, and making a groove.

  Unlike the case where the outer diameter is measured at a certain sampling interval, the outer diameter of the elastic roller is measured for each desired amount of movement of the core metal, so that the elastic roller in the length direction of the core metal is not required for calculation. A film thickness profile of the rubber layer can be obtained. For example, when the core metal is fed to the crosshead die by the feed roller, the transmission of torque to the core metal is weakened due to wear of the feed roller, and the actual feed speed of the core metal may not be a desired speed. Therefore, it is more preferable to directly measure the movement amount of the cored bar.

  As another method, a laser Doppler measuring device can also be used.

  The method for producing the elastic roller of the present invention described above will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

[Example 1]
The composition of the unvulcanized rubber composition used is shown below.
<Preparation of unvulcanized rubber composition>
Materials described in the following material list (a) were added to 100 parts by mass of acrylonitrile butadiene rubber (trade name “NIPOL N230SV”: manufactured by JSR Corporation), and kneaded for 15 minutes with a pressure kneader. Further, the materials described in the following material list (b) were added and kneaded with an open roller for 15 minutes to prepare an unvulcanized rubber composition. Thereafter, unless otherwise specified, this unvulcanized rubber composition was used as an unvulcanized rubber composition.
Material list of (a) Carbon black (trade name “Toka Black # 7360SB”: Tokai Carbon, DBP oil absorption 87) 48 parts by mass,
-1 part by weight of zinc stearate,
-5 parts by mass of zinc oxide (Zinc Oxide Two Kinds of Chemical)-20 parts by mass of calcium carbonate (trade name "Nanox # 30" manufactured by Maruo Calcium Co., Ltd.) (b)-Dibenzothiazolyl disulfide ( Product name "Noxeller DM-P": manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part by mass, tetrabenzylthiuram disulfide (trade name "Noxeller TBZTD": manufactured by Ouchi Shinsei Chemical Co., Ltd.) 4.5 parts by mass, sulfur (Vulcanizing agent) 1.2 parts by mass <Production of rubber roller>
A core metal of SUM24, which is a general-purpose free-cutting steel having an outer diameter of 6 mm and a length of 250 mm, in which an adhesive is applied to a region excluding both ends 12 mm, was prepared. The adhesive used was an electrically conductive hot melt type. An apparatus having the configuration shown in FIG. 1 was used as a crosshead extrusion apparatus. A general-purpose rubber extruder (45 mm extruder manufactured by Mitsuba Corporation) and a crosshead die having a die nozzle inner diameter of φ9.0 mm were used. As outer diameter measuring instruments, LS-7500 and LS-7030M manufactured by Keyence Corporation were used, and were installed at a position of about 20 mm from the outlet of the crosshead die. Screw speed of the extruder so that the discharge speed of the unvulcanized rubber composition (extrusion amount per unit time) by the extruder 1 (FIG. 1) becomes the predetermined outer diameter of the elastic roller at the feed rate shown below. Was about 10.5 rpm. In order to shape the outer profile of the rubber layer coated around the core metal into a crown shape, the core metal feed roller was programmed in advance so that the moving speed of one core metal was changed. FIG. 7A shows the speed (movement speed) at which each position (part) of the core metal is pushed out from the die nozzle 11 by changing the feed speed of the core metal, that is, the movement speed in one core metal. At both ends of the core 1 (core positions: 0 mm and 250 mm), the feed rate is 24.0 mm / s, and the feed rate is gradually lowered toward the center to reduce the center (core). In gold position: 125), it was set to 20.4 mm / s. By adjusting in this way, the outer diameter of both ends of the rubber roller (core metal positions: positions of 0 mm and 250 mm) is about 8.35 mm. Further, the outer diameter of the rubber roller gradually increases toward the center, and is about 8.60 mm at the center (core metal position: 125 mm). Therefore, a gentle crown shape is formed. The moving speed of the core metal is periodically given to each core metal inserted into the cross head continuously by the core metal feed roller. In this embodiment, as shown in FIG. 1, the rear end of the preceding core is pushed and moved by the subsequent core. Therefore, the rear end of the preceding core bar and the leading end of the subsequent core bar always come into contact with each other, and the unvulcanized rubber composition does not enter between them. In synchronization with the change in the moving speed, a rubber roller having an outer diameter changed corresponding to this speed was formed. FIG. 7 (c) shows the result of measuring and comparing the outer diameter measured by the outer diameter measuring device at the die exit during the molding of the elastic roller and the outer diameter at each position of the shape of the elastic roller vulcanized at 160 ° C. for 1 h. Shown in As can be seen, the outer diameter of the elastic roller contracts after vulcanization compared to the molding. However, it can be seen that there is no change in the profile of the outer diameter in the length direction of the cored bar. The outer diameter is measured from the profile of the moving speed of the core bar programmed in advance on the core bar feed roller so that the amount of movement of the core bar becomes 5 mm pitch. Using the calculated measurement time interval, measurement was performed continuously and periodically for each cored bar. The measurement time interval at that time is shown in FIG. Of course, it is possible to increase the feed speed at the central portion to form a gentle inverted crown shape, and it is also possible to make a tapered rubber roller by sequentially increasing the feed speed from one end to the other end.

[Example 2]
The outer diameter profile of the rubber layer of the rubber roller was continuously measured using a method of detecting the amount of movement of the metal core using the rotary encoder illustrated in FIG. As shown in FIG. 5, a rotary encoder is mounted coaxially with the center of rotation of the core metal feed roller so as to synchronize with the rotation of the core metal feed roller. At this time, the diameter of the cored bar feed roller was set to 60 mm, and a rotary encoder of the same size was used. Therefore, even when the moving speed of the cored bar changes due to the pre-programmed rotation of the cored bar feeding roller, the cored bar feeding roller is detected by detecting the radius of the cored bar feeding roller and the rotation angle of the cored bar feeding roller by the rotary encoder. The amount of movement of the metal core can be detected from the product of the radius and the rotation angle. The measurement of the outer diameter was set so that the amount of movement of the core metal was 5 mm. At this time, using an unvulcanized rubber composition having the same composition as in Example 1 and a crosshead extrusion device, an unvulcanized rubber roller was formed under the same conditions of the core metal feed roller as in Example 1, and the outer diameter was It was measured. A rubber roller in which the outer diameter of the rubber roller had the same crown shape as in Example 1 was obtained. FIG. 8A shows the result of measuring the outer diameter at each position of the rubber roller during molding and the result of measuring the shape of the roller after vulcanization in the same manner as in Example 1.

Example 3
As shown in FIG. 6, a method of directly detecting the amount of movement of the metal core by using a metal core with a marking on the metal core to be fed into the cross head and detecting the marking position with a fiber sensor is used. The outer diameter profile of the rubber layer of the rubber roller was continuously measured. At this time, using an unvulcanized rubber composition having the same composition as in Example 1 and a crosshead extrusion device, an unvulcanized rubber roller was formed under the same conditions of the core metal feed roller as in Example 1, and the outer diameter was It was measured. A black marking was applied to the cored bar using an inkjet marking device at a pitch of 5 mm on the same cored bar as in Example 1. Furthermore, using the reflective fiber sensor FU-20 manufactured by Keyence, the marking position of the metal core is detected based on the difference in reflectance between the metal surface and the black marking, and the outer diameter of the rubber roller is measured based on that. went. FIG. 8B shows the result of measuring the change in outer diameter at each position of the rubber roller during molding and the result of measuring the shape of the roller after vulcanization in the same manner as in Example 1.

[Comparative Example 1]
At this time, using an unvulcanized rubber composition having the same composition as in Example 1 and a crosshead extrusion device, an unvulcanized rubber roller was formed under the same core metal feed roller conditions as in Example 1, and the outer diameter was , And measured at a constant cycle every 0.25 seconds. FIG. 8C shows the result of measuring the change in outer diameter at each position of the rubber roller during molding and the result of measuring the shape of the roller after vulcanization in the same manner as in Example 1. FIG. 8 (c) shows that there is a difference between the shape of the vulcanized roller and the shape of the elastic roller measured at the time of roller molding. The outer diameter data measured at the time of molding the roller is shifted as a result of the movement of the cored bar due to the relationship between the feed speed of the cored bar and the position of the outer diameter measuring instrument, and as a result, is measured as an asymmetric shape. There is no influence on the shape of the roller actually formed.

  However, when performing roller molding at a factory for a long time, in order to prevent the shape of the roller being molded from deviating from the desired range due to fluctuations in the discharge amount of the extruder, In general, feedback control to an extruder is performed based on a measured value.

  When the roller shape measured at the time of molding is different from the roller shape after vulcanization as in Comparative Example 1, when setting the roller for a long time, the setting of the extruder or the core metal It is difficult to perform feedback control that changes the feed rate.

1 ... Extruder 2 ... Crosshead die 3 ... Core metal feed roller 4 ... Core metal stocker 5 ... Core metal 6 ... Material inlet 7 ... Unvulcanized rubber composition 8 ... Cutting and drawing Removal process 9 ... Outside diameter measuring instrument

Claims (2)

A plurality of metal cores are continuously and serially supplied to the core metal supply holes of the cross head, and a molten rubber mixture is supplied to the cross head from an extruder connected to the cross head, so that the periphery is made of rubber. A method for producing an elastic roller comprising a step of producing a plurality of cored bars coated with a layer of a mixture,
(1) changing the film thickness of the rubber mixture covering the periphery of each of the core bars by changing the feed rate or the take-up speed of the core bar to the crosshead;
(2) measuring the outer diameter of the core metal coated with the rubber mixture layer using an outer diameter measuring device provided at the outlet of the crosshead,
In the step (2), the outer diameter is measured for each predetermined moving distance of the cored bar, and the elastic roller is produced.   The method for manufacturing an elastic roller according to claim 1, wherein in the step (2), the movement distance of the core metal is detected by measuring the distance of movement of the core metal itself.

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