JP2004148603A - Mold for molding development blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for molding a development blade which can easily separate a runner mark and a gate mark from the molded development blade. <P>SOLUTION: In the mold for injection-molding a blade main body 12 which is in touch with a development roll and is made of an elastic member and an elastic support member which supports the blade main body 12, the diameter on the cavity side of the gate 14 of the mold is made smaller than the diameter on the runner 13 side, and a narrow part is formed in the gate 14, so that the gate mark can easily be wrenched off from the molded blade main body 12. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold for injection-molding a developing blade used in a developing device of a copying machine such as a laser printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a copying machine such as an electrophotographic copying machine or a laser printer, an electrostatic latent image is formed on a photosensitive drum, toner is attached to the electrostatic latent image by a developing device, and the electrostatic latent image is visualized. The image is transferred to a storage medium such as.
FIG. 4 is a view showing an outline of a conventional developing device. The developing device 50 accommodates a toner 52 as a developer inside a housing 51, and agitates the toner 52 with a stirrer 53 to form a toner supply roll. The developer is supplied to the surface of the developing roll 55 via the developing roller 55. Then, the toner 52 supplied to the surface of the developing roll 55 by the developing blade 20 is regulated to a uniform thin layer, and the toner 52 is triboelectrically charged. The toner 52 is conveyed to the developing area of the photosensitive drum 56 facing the developing roll 55 with the rotation of the developing roll 55, and adheres to the electrostatic latent image formed on the surface of the photosensitive drum 56. It is configured.
[0003]
As shown in FIG. 5, the developing blade 20 is provided with a blade body 22 made of silicone rubber having a convex cross section at one end of a metal plate 21 which is a support member having one end fixed to the housing 51. The metal plate 21 is often used, and is usually manufactured by insert molding using the metal plate 21 as an insert member.
Specifically, as shown in FIG. 6, a metal plate 21 as an insert member is inserted into a cavity 33 of a mold 30 for molding the blade body 22 formed by a fixed mold 31 and a movable mold 32. The metal plate 21 is fixedly installed in the mold 30 with the positioning pin 34 so that the tip end projects, and corresponds to the end 22 b of the cavity 33 on the metal plate 21 side of the blade body 22. From a gate 35 (see FIG. 5) provided at the location, liquid silicone rubber, which is pressure-fed from a not-shown injection device via a runner 36, is injected into the cavity 33 and solidified.
[0004]
By the way, as shown in FIG. 7A, the blade body 22 after molding has a gate 35 at an end of a surface (back surface) 22b opposite to the surface 22a in contact with the developing roll. Since the molding members (runner traces, gate traces) 35m and 36m having the shape of the gate 35 and the runner 36 are integrally formed, in the subsequent process, the gate is moved from the blade body 22 as shown in FIG. A so-called gate cut operation is performed to separate the trace 35 m and the runner trace 36 m.
[0005]
[Problems to be solved by the invention]
However, since the gate 35 of the conventional mold 30 is generally straight in the direction of the cavity 33, the gate mark 35m and the runner mark 36m may be cut on the same plane as the back surface 22b of the blade body 22. It is difficult, so that it takes time to cut the gate, and there is a possibility that the back surface 22b of the blade body 22 may be damaged.
[0006]
The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a developing blade molding die that can easily separate runner marks and gate marks from a formed developing blade. .
[0007]
[Means for Solving the Problems]
The present inventors have made intensive studies and as a result, it is possible to solve the above-mentioned problem by setting the gate shape of the mold to a shape that allows easy removal of the gate mark from the blade body after molding. This has led to the present invention.
That is, according to the first aspect of the present invention, there is provided a metal mold for injection-molding a developing blade having a blade main body made of an elastic member, which comes into contact with a developing roll, and an elastic supporting member supporting the blade main body. In the mold, the diameter of the gate of the mold on the cavity side is smaller than the diameter on the runner side.
According to a second aspect of the present invention, a narrow portion is provided in the gate of the mold.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing an embodiment of the present invention. Reference numeral 10 denotes a developing blade formed by integrally molding a blade body 12 made of silicone rubber on a metal plate 11 as an insert member. As shown in FIGS. 2A and 2B, the shape of the tip of the mold gate 14 for manufacturing the blade 10 is such that the diameter of the blade body 12 is smaller than the diameter of the runner 13. It has a tapered shape. The basic configuration of the mold for forming a developing blade used in this example is the same as the conventional mold 30 shown in FIGS. 5 and 6 except for the shape of the gate 14.
Since the gate 14 of the present example is tapered toward the blade body 12, the notch K is provided at the connection between the blade body 12 and the gate 14, as shown in FIG. 2B. Shape. Therefore, after molding, as shown in FIG. 2C, the gate trace 14m remaining at the end of the blade main body 12 is simply removed from the cut portion K, and the runner trace 13m and the gate trace 14m are removed. It can be easily separated from the blade body 12.
Therefore, the conventional gate cut is not required, so that the developing blade 10 can be efficiently and stably manufactured. Further, since the back surface of the blade body 12 is not damaged or a foreign substance is not attached when the gate is cut, the quality of the developing blade 10 can be improved.
[0009]
In the above example, a tapered portion is provided at the tip end of the gate 14 so that the gate mark 14m can be easily removed. However, the gate shape according to the present invention is not limited to this. For example, FIG. (B) As shown in (b), the gate shape may be such that the runner trace 13m and the gate trace 14m are easily removed from the blade body after molding, such as by providing a narrow portion 14k in the middle of the gate 14.
[0010]
【The invention's effect】
As described above, according to the present invention, a blade main body made of an elastic member, which comes into contact with the developing roll, and a supporting blade having elasticity, which supports the blade main body, and a developing blade molding die for injection molding, Since the diameter of the cavity of the mold gate on the cavity side is smaller than the diameter on the runner side, and the gate has a narrow portion, the gate mark can be easily removed from the blade body after molding. , Runner marks and gate marks can be easily separated from the blade body. Therefore, since the gate cut can be omitted, the developing blade can be efficiently and stably manufactured.
Further, since the blade main body is not damaged or foreign matter is not attached at the time of gate cutting, the quality of the developing blade can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing a state of a developing blade after molding.
FIG. 3 is a diagram showing a state after molding of a developing blade provided with a narrow portion in a gate.
FIG. 4 is a diagram illustrating an outline of a developing device.
FIG. 5 is a diagram showing a conventional method for manufacturing a developing blade.
FIG. 6 is a cross-sectional view of a main part showing a conventional developing blade molding die.
FIG. 7 is a view showing a state after molding of a conventional developing blade.
[Explanation of symbols]
10 developing blade, 11 metal plate, 12 blade body,
13 runners, 13m runner traces, 14 gates, 14m gate traces.

Claims (2)

A mold for injection-molding a developing blade having a blade main body made of an elastic member, which is in contact with the developing roll, and supporting the blade main body, having a support member having elasticity; A mold for forming a developing blade, wherein the diameter on the cavity side is smaller than the diameter on the runner side. A mold for injection-molding a developing blade having a blade main body made of an elastic member, which comes into contact with the developing roll, and a supporting member having elasticity, which supports the blade main body. A mold for forming a developing blade, comprising a narrow portion.

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