JPH04320813A - Manufacture of roller - Google Patents

Abstract

PURPOSE:To manufacture a heat vulcanized silicone rubber roller of one layered structure by the use of an injection mold and in non-grinding. CONSTITUTION:The cylindrical mold 5 of a first mold 11 is held by a right mold 6 and left mold 7 where grooves 62, 71 are made respectively. Into the right and left molds 6,7, a core metal 2 surrounded by the cylindrical mold 5 is fitted coaxially, and further the first mold 11 is covered by a second mold 12 equipped with a rubber injection hole 121 communicated to a circumferential groove 61 made at the right mold 6. Heat vulcanization-type silicone rubber is force-fed into the gap between the cylindrical mold 5 and the core metal 2 passing through the circumferential groove 61 and a groove 62 from the rubber injection hole 121, and then vulcanization-molded for obtaining a silicone rubber roller of non-ground and one layered structure. Thus, in use of a heat vulcanization-type silicone rubber to which a conductive filling agent can be applied freely, a roller with good properties can efficiently be manufactured in non-grinding in one layered structure, moreover, at low cost because of the non-grinding.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing rollers used for toner fixing and development in electronic copying machines and the like.

0002

[Prior Art] With the spread of electronic copying machines and laser printers, devices have become smaller and have less weight, and in response, the toner fixing units and developing rollers used in these devices have also become smaller. , lower hardness is required. Therefore, rollers have been developed that use low-hardness rubber to form rollers that can be made without grinding. In particular, the developing roller has a volume resistance value of 108Ω due to the relationship with the toner.
It must be chemically stable, have a conductivity of less than cm, have sufficient elasticity, have low compression set, and have a low coefficient of friction and a smooth surface to improve paper passing, making it difficult to wear. Must be. Therefore, urethane on the core metal,
A two-layer roller was constructed by coating an elastic body made of a rubber material such as EPDM, NBR, or silicone with a hard-to-wear resin such as polyurethane resin.

0003

[Problems to be Solved by the Invention] However, a roller with a two-layer structure increases costs and reduces production efficiency, so in order to simplify the manufacturing process, a roller with a single-layer structure using liquid rubber has been developed. ing. However, condensation reaction type silicone rubber (RTV) and addition reaction type silicone rubber (
When a liquid rubber (LTV) was used, the addition of a conductive filler to impart conductivity increased the viscosity, making normal injection molding impossible. Further, even if the roller was press-fitted, a homogeneous roller could not be obtained. Furthermore, although conductive fillers can be freely added to heat-curable silicone rubber (HTV), grinding is required due to processing methods such as extrusion molding and sheet wrapping.

[0004] The present invention has been made in order to eliminate the above-mentioned drawbacks, and provides a method for manufacturing a roller with good characteristics, which has a low volume resistance value, is conductive, and has a uniform wall thickness without grinding. With the goal.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a roller of the present invention includes a cylindrical mold that coaxially surrounds a core metal, and a cylindrical mold that fits and clamps the core metal. left and right molds that sandwich the cylindrical mold through a circumferential groove drilled in the circumferential direction on at least one side and a plurality of grooves drilled at equal intervals in the radial direction from the circumferential groove. The first mold is covered with a second mold that has a rubber injection hole that reaches the circumferential groove and includes a pair of clamping bodies that enclose the first mold, and the rubber injection mold is injected into the first mold. After heat-vulcanizing silicone rubber is press-fitted through the hole, it is heat-vulcanized and manufactured without grinding.

[0006]

[Operation] The mold for the heat-curable silicone rubber roller consists of a first mold consisting of a core metal and a cylindrical mold coaxially surrounding the core metal, which are sandwiched between left and right molds, and a first mold. and a second mold enclosing the mold. A circumferential groove formed in the circumferential direction and a plurality of grooves connected to the circumferential groove at equal intervals in the radial direction are formed in at least one of the left and right molds of the first mold. The second mold is provided with a rubber injection hole connected to the circumferential groove of the first mold, and when rubber is press-fitted through the rubber injection hole,
After the rubber is applied in the circumferential direction through the circumferential groove, heat-curable silicone rubber is evenly injected between the cylindrical mold and the core metal from the groove of the first mold, so that the rubber spreads around the core metal. Injected evenly around the area. Air and excess rubber escape from the grooves provided in the other of the left and right molds of the first mold.

By using such a mold, a heat-curable silicone rubber roller can be produced by injection molding without grinding.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the roller manufacturing method of the present invention will be described with reference to the drawings. The mold 1 shown in FIG. 1 is used to create a rubber roller 4 having an elastic layer 3 made of heat-curable silicone rubber (hereinafter referred to as HTV) on a core bar 2 shown in FIG. and a second mold 12 consisting of a pair of clamping bodies 12a enclosing the first mold 11. The first mold 11 includes a cylindrical mold 5 and a cylindrical mold 5.
It consists of a right mold 6 and a left mold 7 that sandwich the mold from the left and right sides. The right and left molds 6 and 7 each have a recess 8 in the center, into which the core metal 2 is fitted. Furthermore, the right mold 6 has a circumferential groove 61 in the circumferential direction.
is provided, connected to the circumferential groove 61 and extending several mm in the radial direction.
A plurality of width grooves 62 are bored at equal intervals, for example, four at 90° intervals. A rubber injection hole 121 connected to the circumferential groove 61 is bored in one side of the clamping body 12a of the second mold 12.
2, solid HTV is injected into the gap 9 between the cylindrical mold 5 and the core metal 2. In addition, a plurality of grooves 71 narrower than the groove 62 are bored in the left mold 7 in the radial direction.
becomes an escape route for air when it is injected into gap 9, and HTV
This serves as an escape route for expansion during vulcanization.

[0009] To manufacture an HTV roller using such a mold 1, transfer molding is performed. Transfer molding is performed by fitting a core metal 2 and a cylindrical mold 5 wrapped with unvulcanized millable silicone rubber thinner than the finished diameter into the recess 8 of either the right or left mold 6 or 7, Fit the other left and right molds together. Cylindrical mold 5 and right and left molds 6
, 7 are coated with a mold release agent in advance. Then, the first mold is covered with the second mold, and the solid HT is poured from the rubber injection hole 121.
Press in V. HTV is supplied in the circumferential direction through the circumferential groove 61 of the right mold 6, and then injected into the gap 9 from the groove 62. Therefore, the HTV is evenly supplied to the core metal 2, and then heated to integrally vulcanize the millable silicone rubber that has been wrapped around the core metal 2 in advance and the press-fitted HTV.

[0010] Here, the volume resistance value of HTV is 108Ω・c
m or more, is conductive, and contains dry silica as a filler. Dry silica average particle size is 30m
μm or more, the abrasion coefficient of the surface during molding is small, the lubricity is good, and it can be easily released from the mold. The roller is released from the mold 1, aged for a predetermined period of time, and molding is completed without grinding. Specific Example HTV mixed with dry silica was injection molded onto a core metal 2 having a diameter of 6 mm by transfer molding using the above mold. φ18 HTV without grinding after vulcanization
Got Laura. The friction coefficient of the obtained roller is 0.3 to 0.
．． 5 (ordinary rollers are 1.5). In addition, there was no problem with durability in the 10,000-sheet paper test, and the compression set was 10%.
It was below.

[0011]

Effects of the Invention As is clear from the explanation for maintenance, according to the roller manufacturing method of the present invention, a second mold consisting of a pair of sandwiched bodies provided with rubber injection holes; The core metal is inserted into the core metal through a circumferential groove and a radial groove formed in one of the left and right molds of the first mold, which is covered with the mold and connected to the rubber injection hole of the second mold. Since the HTV is press-fitted into the gap between the roller and the cylindrical mold, a roller with a uniform thickness can be manufactured by injection molding even with solid HTV. In addition, since a filler for imparting conductivity can be appropriately added in a desired amount, a roller with good characteristics can be obtained.

Furthermore, since dry silica is mixed, the surface has good slipperiness even if it has a single layer structure, and a roller can be obtained without grinding. Therefore, the manufacturing process is simplified, the roller can be manufactured at low cost, and production efficiency can be improved.

[Brief explanation of drawings]

[Fig. 1] A cross-sectional view of an embodiment of a mold for the roller manufacturing method of the present invention.

[Fig. 2] Cross-sectional view of a roller obtained by the present invention

[Explanation of symbols]

1... Mold 2... Core metal 5...Cylindrical mold 6...Right mold 7...Left mold 11...First mold 12...Second mold 12a... sandwiched body 61... Circumferential groove 62, 71... Groove 121...Rubber injection hole

Claims (1)

[Claims] 1. A cylindrical mold that coaxially surrounds a cored metal, a circumferential groove that fits and holds the cored metal and is bored in the circumferential direction on at least one side, and a cylindrical mold that surrounds the cored metal coaxially, and A first mold including left and right molds that sandwich the cylindrical mold through a plurality of grooves equally spaced in the direction, and a first mold having a rubber injection hole reaching the circumferential groove and The first mold is encapsulated by a second mold consisting of a pair of sandwiched bodies, and after press-fitting a heat-curable silicone rubber through the rubber injection hole, the mold is heat-vulcanized and manufactured without grinding. A method for manufacturing a roller, characterized by: