JP4707481B2 - Mold for molding elastic roller made of foam, and method for manufacturing the roller - Google Patents

Description

The present invention, mold the elastic roller made of a foam, it relates to the production how of the roller. In particular, an elastic roller made of foam mounted on a developing device used to develop and visualize an electrostatic latent image formed on an image carrier made of an electrophotographic photosensitive member or an electrostatic recording derivative. mold, in which relates to the production how of the roller.

In recent years, due to demands for miniaturization, high image quality, and low price of electrophotographic apparatuses, high precision and low performance for functional rollers such as toner supply rollers, charging rollers, and transfer rollers incorporated in the electrophotographic apparatuses. Pricing has been required.
On the other hand, efforts have been made to reduce the manufacturing cost while maintaining the quality of the functional roller in response to these requirements.
Further, in mass production of rollers, it is indispensable to automate the manufacturing apparatus to some extent. For this reason, a manufacturing apparatus that can be easily automated while maintaining the quality of the roller has been demanded.

Under such circumstances, an elastic roller made of a foam, which is one of such functional rollers, has been generally manufactured using a molding die.
As such a molding die, for example, in Patent Document 1, a cored bar is arranged at the center, and a raw material is injected into a pipe-shaped molding die to be foamed and solidified. A method for manufacturing a roller made of The molding die includes a cylindrical die 31 having both ends opened as shown in FIG. 5A, lid portions 32 and 33 mating with both ends of the cylindrical die 31, and FIGS. It is comprised by the axis | shaft 36 used as the core metal of the roller which can be inserted from the insertion port 35 of the cover part 33 shown to b). Here, the lid portion 32 is provided with an injection hole for injecting a foam material, which is a raw material, and the raw material is injected directly into the cylindrical mold 31 from the injection hole to be foamed and solidified. By removing this from the cylindrical mold 31, a foam for a roller having a shaft 36 shown in FIG. 5C is obtained.

By the way, when the raw material is injected into such a molding die, pressure adjustment with high accuracy is required in order to minimize foaming unevenness and density difference of the foamed elastic body. Therefore, for example, in Patent Document 2, an air vent is applied to a portion corresponding to the one lid portion of FIG. 5 described above so that the air in the cavity is released to the outside and the pressure inside the mold is adjusted during molding by the mold. Manufacturing methods have been proposed.
JP-A-5-329855 Japanese Patent Application Laid-Open No. 10-075535

  However, in the above-described conventional example, if the area of the air vent gap (vent sectional area) is not appropriate, the raw material may overflow from the gap to the outside of the mold during molding, or the air in the mold Has a problem that it cannot completely escape to the outside. In addition, there is a problem that abnormal foaming such as voids in the molded product (large air accumulation due to cell connection or the like) and foaming unevenness occurs due to the influence of the mold internal pressure.

In view of the above problems, the present invention comprises a foam that suppresses abnormal foaming such as voids and uneven foaming of a molded product, overflow of the raw material to the outside of the mold, and eliminates the occurrence of air accumulation in the molded product. mold of the elastic roller, it is an object to provide a manufacturing how of the roller.

The present invention, in order to achieve the above object, mold the elastic roller made of the structure described below the foam, there is provided a manufacturing how of the roller.
That is, the mold for molding the elastic roller made of the foam of the present invention is:
A cylindrical mold having both ends opened, and before Symbol second frame type to the first frame type and the other a篏合to one and篏合opening at both ends, the disposed in the cylindrical mold in the For molding a cylindrical elastic roller made of a foam on the outer periphery of the core material, and having a core material that can be held by a core material holding portion formed in a single frame type and a second frame type Mold,
Wherein formed between the mating surfaces of the first frame type before Symbol opening before Symbol cylindrical mold, a first air vent groove which also serves as an inner pressure adjustment and air vent of the cylindrical mold,
Formed on the bottom surface of the first piece shape from the surface on the core material side of the holding portion of the core material formed in the first piece shape toward at least two directions in the outer peripheral direction of the first piece shape , A second air vent groove comprising a groove portion for allowing the air around the core material held by the holding portion to escape to the outside;
It is characterized by having.
In addition, the method for producing an elastic roller made of the foam of the present invention includes:
A cylindrical mold having both ends opened, and before Symbol second frame type to the first frame type and the other a篏合to one and篏合opening at both ends, the disposed in the cylindrical mold in the using a mold to have a the possible and have been the core held by the holding portion of one frame type and the core material formed in the second piece type, cylindrical elastic roller made of foam on the outer periphery of the core member An elastic roller manufacturing method for manufacturing
Wherein in the production of the elastic roller made of a foam, using a mold of the elastic roller comprising a foam according to claim 2 as said mold, said core member arranged in the cylindrical mold within the A process of pre-heating at a predetermined temperature by holding both ends of the core member in a cylindrical mold by holding the core member formed in the first piece type and the second piece type, and assembling them.
As a step of filling foam material into the preheated cylindrical mold,
The liquid receiving part is preheated, the foamed material is accommodated in the preheated liquid receiving part, and then the liquid receiving part in which the foamed material is accommodated is assembled to the preheated cylindrical mold, and the second piece Filling the cylindrical mold by natural foaming of the foam material in the liquid receiving portion through a foam material filling port provided in the mold; and
Controlling the temperature of the cylindrical mold filled with the foamed material to a predetermined temperature, curing the foamed material, and demolding;
It is characterized by having .

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress generation | occurrence | production of the air pocket with respect to a molded product by suppressing abnormal foaming, such as a void of a molded product, foaming nonuniformity, and the overflow of the raw material outside a metal mold | die.

Hereinafter, as an example of a molding die according to an embodiment of the present invention, a molding die for an elastic roller made of a foam (hereinafter referred to as a foamed elastic roller) will be described with reference to the drawings.
FIG. 1 shows the configuration of a molding die for a foamed elastic roller, which is an example of an embodiment of the present invention.
FIG. 2 shows the configuration of the foamed elastic roller molded by the molding die in the embodiment of the present invention.
In FIG. 1, 1 is an upper piece type, 2 is a cylindrical molding die, 3 is a lower piece type, 4 is a liquid receiving cup, and 5 is a core.
At the center of the upper piece mold 1 and the lower piece mold 3, a core material holding portion for holding the core material 5 is formed.
Reference numeral 6 denotes a foam having a core material 5 taken out from the cylindrical molding die 2 after molding, and reference numeral 7 denotes a foam material filling port formed in a lower piece shape.

Initially, the outline at the time of shape | molding a foaming elastic body roller using the metal mold | die of such a structure is demonstrated.
First, the core material 5 is arranged in the molding die 2, the upper and lower portions of the core material 5 are held by the core piece holding portions of the upper piece mold 1 and the lower piece mold 3, and the core material 5 is set. Is preheated at a predetermined temperature. On the other hand, after the foam material is discharged into the liquid receiving cup 4 that has been preheated to a predetermined temperature, it is assembled to the molding die 2. The foam material in the liquid receiving cup 4 is filled into the molding die 2 through the foam material filling port 7 by natural foaming. Thereafter, the foamed material roller is obtained by curing the foamed material by controlling the temperature at a predetermined temperature for a predetermined time and removing the foamed material.

The above is the outline of the foamed elastic roller molding process in the present embodiment. At this time, in the present invention, the first air vent groove and the second air vent groove are formed in the upper piece mold, and the air reservoir is formed outside the mold. It is characterized in that it is discharged and the foamed rubber roller is stably molded.
Next, these characteristic configurations will be described with reference to FIG.
FIG. 3 is a view showing the configuration of the upper piece of the molding die for the foamed elastic roller of the present embodiment,
(A) is a figure which shows the structure by which the 1st air vent groove and the 2nd air vent groove were formed in the top piece type | mold,
(B) is a figure explaining the state by which the air pool by an air vent groove is discharged | emitted by the mold exterior .
In FIG. 3, 10a is a first air vent groove and 11a is a second air vent groove.
Further, 20 is a foam material in the mold, 21 is an air reservoir around the core material, and 22 is an air reservoir on the mold wall surface.
The upper piece mold 1 is configured to engage with a fitting recess formed in an upper opening of a cylindrical molding die 2. Here, as shown in FIG. 3 (a), a first air vent groove 10a that serves as both in-mold pressure adjustment and air bleeding is provided between the fitting surfaces of the fitting recess and the upper piece mold 1. Is formed.
Moreover, it is formed in the bottom face of the upper piece mold 1 from at least two directions in the outer peripheral direction from the face of the holding part of the core member 5 provided on the bottom face and held by the holding part. A second air vent groove 11a comprising a groove part for releasing air around the core material to the outside is provided.

  In the present embodiment, the material for the second air vent groove 11a is formed by forming the second air vent groove 11a on the bottom surface of the upper piece mold 1 and setting the groove width to 0.03 to 2 mm, for example. A resistance is given at the time of intrusion, and the air reservoir 21 around the core material 5 held by the holding part of the upper piece mold 1 before the material fills the groove can be discharged to the outside of the mold.

On the other hand, as in the comparative example shown in FIG. 4A, the pressure inside the mold is adjusted between the fitting concave portion formed in the upper opening of the molding die 2 and the fitting surface of the upper piece die 1. In the case where only the first air vent groove 10b that also serves as a part is formed, an air reservoir remains in the mold.
According to the configuration of such a comparative example, as shown in FIG. 4 (b), the foam material 20 injected into the mold slows down the flow of the material near the mold wall surface and the core wall surface, and the other parts are The mold is filled with foam in a raised shape. The rise of the material tends to increase as the foamed material is highly foamed. When foaming is performed up to the end of filling in the mold in this state, air pools 21 and 22 are generated around the core material and on the mold wall surface. The air pool on the mold wall is discharged to the outside of the mold by the first air vent groove 10b, but the air pool 21 around the core material remains without being discharged.

Moreover, in this Embodiment, abnormal foaming, such as a void and a foaming nonuniformity, can be suppressed by comprising so that the cross-sectional area of the 1st air vent groove | channel 10a may be regulated and pressure adjusted. The first air vent groove 10a is arranged at least one groove, preferably four or more, between the fitting surfaces of the molding die 2 and the fitting recess. The total cross-sectional area of the groove in view of the pressure adjustment 0.1 to 1.0 mm ^2, and it is preferably a 0.03~0.06mm ^2.

It is preferable that the sizes of the first air vent groove and the second air vent groove are appropriately selected depending on the viscosity of the foam material used and the foaming ratio.
The material of the mold is not particularly limited as a mold member. For example, a metal member obtained by plating a steel material such as iron with nickel or chromium, or a metal member such as iron, copper, aluminum, stainless steel, or pre-hardened steel can be used. Besides these, synthetic resins such as polycarbonate and polyamide, ceramics, and the like can be used as appropriate.

According to the present embodiment described above, by regulating the gap in the first air vent groove that serves as both the pressure adjustment in the mold and the air release, abnormal foaming such as voids and uneven foaming of the molded product can be eliminated, and the gap Intrusion of raw materials can be minimized, and overflow of raw materials can be prevented.
Further, the second air vent groove formed by a groove portion for escaping the air provided on the lower surface of the upper piece mold 1 to the outside prevents the air pool from being generated in the molded product by discharging the air pool to the outside of the mold. Is possible.
Conventionally, both ends of the molded foam rubber portion are provided with a cut-off allowance in consideration of air accumulation around the core material . However, according to the present embodiment, air accumulation does not occur, so that the cut-off allowance can be reduced, and the material can be used effectively without waste.
The configuration in the present embodiment as described above is more effective as the foaming ratio of the foam material used for filling in the molding die is higher.

Although the manufacturing method of the foam rubber roller in the Example to which this invention is applied is demonstrated below, this invention is not limited at all by these Examples.
In this embodiment, a molding die having a structure basically similar to that of the molding die shown in FIG. 1 was used.
In the present embodiment, the first air vent groove is arranged in four equally divided grooves between the fitting surfaces of the molding die 2 and the upper piece die 1. Further, a second air vent groove having grooves cut in four directions from the central axis of the core member 5 to the outer peripheral direction was arranged on the lower surface of the upper piece mold 1 equally.
Here, the cross-sectional area per one first air vent groove, the total cross-sectional area be 0.055 mm ² was 0.22 mm ^2.
The second air vent groove has a semicircular groove structure having a width of 1 mm and a depth of 1 mm.
As the material of the mold, SUS304 is used for the mold 2, and the upper piece mold 1, the lower piece mold 3, and the liquid receiving cup 4 are made of surface-treated chemical nickel of HPM 38 (pre-hardened steel). Produced.

Next, the material of the molded foam rubber roller, molding conditions, and manufacturing procedure will be shown.
In implementation, a foamed rubber roller having the shape shown in FIG. 2 was molded.
First, as a mixed polyol, FA-908 (Sanyo Chemical Co., Ltd. polyether polyol) 100 parts by weight, diethanolamine 0.5 part by weight, L5366 (Nihon Unicar Co., Ltd. silicone-based foam stabilizer) 1 part by weight, ToyoCat-ET (Tosoh Co., Ltd. tertiary amine catalyst) 0.1 weight part, TEDA-L33 (Tosoh Co., Ltd. tertiary amine catalyst) 0.5 weight part, Water (foaming agent) 2 weight part was mixed. Then, TCO (Mitsui Takeda Chemical Co., Ltd. isocyanate, NCO% = 48) 29.5 parts by weight, M200 (Mitsui Takeda Chemical Co., Ltd. isocyanate, NCO% = 31) 7.4 parts and NCO index 100 A foamed material was prepared by mixing and stirring.

A silicone oil release agent was applied to the molding die 2 of this example, a core metal of φ5 × 260 mm (L) was set in the die, and preheated to 65 ° C. Thereafter, the foamed material mixed and stirred was discharged into a liquid receiving cup preheated to 65 ° C. and assembled with a mold.
At this time, since the molding material discharged to the liquid receiving cup is a foamed material, the molding die 2 is filled with the material by natural foaming through the filling port 7.
Thereafter, it was cured on a hot plate controlled at 65 ° C. for 10 minutes, and demolded to obtain a foamed rubber roller of this example. The foamed rubber roller has a foam outer diameter of φ12 and a foam part length of 220 mm.
The air pool that was always generated in the conventional molding die became 0% by using the molding die of the present example (however, the air reservoir due to the cell communication of the foam was excluded). With the mold of this example, the pressure inside the mold was maintained, so that it was possible to stably mold a foamed rubber roller free from abnormal foaming such as voids and uneven foaming and having no air accumulation.

The figure which shows the structure of the metal mold | die for a foaming elastic body roller which is an example of embodiment of this invention. The figure which shows the structure of the foaming rubber roller shape | molded with the metal mold | die for a foaming elastic body roller of FIG. 1 in embodiment of this invention. It is a figure explaining the structure of the upper piece type | mold of the metal mold | die for foaming elastic body rollers of this Embodiment, (a) is the structure by which the 1st air vent groove and the 2nd air vent groove were formed in the upper piece type | mold. FIG. 5B is a diagram showing a state where an air pool by the air vent groove is discharged to the outside of the mold. It is a figure explaining the structure of the metal mold | die for foaming elastic body rollers in a comparative example, (a) is a figure which shows the structure by which only the 1st air vent groove | channel was formed in the upper piece type | mold, (b) is the circumference | surroundings of a core material The figure which shows the state in which the air reservoir remains in a type | mold. The figure which shows the structure of the metal mold | die for a foaming elastic body roller of patent document 1 which is a prior art example.

Explanation of symbols

1: Upper piece mold 2: Cylindrical molding die 3: Lower piece mold 4: Liquid receiving cup 5: Core material 6: Foam 7: Foam filling port 10a: First air vent groove 10b: First air vent groove 11a : Second air vent groove 20: mold material flow 21: air pool around core material 22: mold wall air pool

Claims (3)

A cylindrical mold having both ends opened, and before Symbol second frame type to the first frame type and the other a篏合to one and篏合opening at both ends, the disposed in the cylindrical mold in the For molding a cylindrical elastic roller made of a foam on the outer periphery of the core material, and having a core material that can be held by a core material holding portion formed in a single frame type and a second frame type Mold,
Wherein formed between the mating surfaces of the first frame type before Symbol opening before Symbol cylindrical mold, a first air vent groove which also serves as an inner pressure adjustment and air vent of the cylindrical mold,
Formed on the bottom surface of the first piece shape from the surface on the core material side of the holding portion of the core material formed in the first piece shape toward at least two directions in the outer peripheral direction of the first piece shape , A second air vent groove comprising a groove portion for allowing the air around the core material held by the holding portion to escape to the outside;
A mold for molding an elastic roller made of a foam. To the second piece type side front Symbol is篏合the other opening of the cylindrical mold, the liquid receiving portion is disposed, the liquid received through the foam material filling port provided in the second frame-type 2. The mold for molding an elastic roller made of a foam according to claim 1, wherein the foamed material in the portion can be filled into the cylindrical mold by natural foaming . 3. A cylindrical mold having both ends opened, and before Symbol second frame type to the first frame type and the other a篏合to one and篏合opening at both ends, the disposed in the cylindrical mold in the using a mold to have a the possible and have been the core held by the holding portion of one frame type and the core material formed in the second piece type, cylindrical elastic roller made of foam on the outer periphery of the core member An elastic roller manufacturing method for manufacturing
Wherein in the production of the elastic roller made of a foam, using a mold of the elastic roller comprising a foam according to claim 2 as said mold, said core member arranged in the cylindrical mold within the A process of pre-heating at a predetermined temperature by holding both ends of the core member in a cylindrical mold by holding the core member formed in the first piece type and the second piece type, and assembling them.
As a step of filling foam material into the preheated cylindrical mold,
The liquid receiving part is preheated, the foamed material is accommodated in the preheated liquid receiving part, and then the liquid receiving part in which the foamed material is accommodated is assembled to the preheated cylindrical mold, and the second piece Filling the cylindrical mold by natural foaming of the foam material in the liquid receiving portion through a foam material filling port provided in the mold; and
Controlling the temperature of the cylindrical mold filled with the foamed material to a predetermined temperature, curing the foamed material, and demolding;
A method for producing an elastic roller comprising a foam.

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