JPH0781785A - Roller and roller molding die - Google Patents

Abstract

PURPOSE:To provide a roller molding die which is constituted to prevent the occurrence of a parting line in an axial direction and burrs on the peripheral surface of a roller. CONSTITUTION:A cylindrical axial mold hole 20 and a body mold hole 24, by which one shaft part 18 and a body 22 are integrally molded, are formed in a moving mold 14, and a cylindrical axial mold hole 28 by which the other shaft part 26 is molded is formed to a fixed mold 12. By mating together the moving mold 14 and the fixed mold 12, molten resin is injected in a cavity and after cooling, a roller 16 as a molding is taken out. Since a parting line and burrs are formed on the peripheral surface of the end part of the body 22 being a parting surface P between the moving mold 14 and the fixed mold 12 and a joint between the body 22 and the shaft part 26, the roller 16 having excellent periphery precision of a peripheral surface is molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller and a roller molding die used in electrophotographic copying machines, laser printers, facsimiles and the like.

[0002]

2. Description of the Related Art Usually, as shown in FIG. 3, a semi-cylindrical mold is used when manufacturing a roller R composed of a cylindrical main body 42 and shaft portions 44 provided at both ends of the main body 42. Hole 4
The upper mold 48 and the lower mold 50 on which 6 is formed are face-to-face, the molten resin is injected into the cylindrical cavity, and after cooling, the mold is split and the roller R is taken out.

However, the roller R thus formed has a parting surface P (a mating surface) between the upper mold 48 and the lower mold 50, that is, a parting line in the axial direction on the circumferential surface of the roller R. L occurs.

Further, the parting surfaces P of the upper mold 48 and the lower mold 50 are heavily worn by the flow of the resin, and the molten resin flows into the worn parts, and burrs B are generated along the axial direction of the roller R. However, the diameter dimension of the roller R may not be within the tolerance.

For this reason, a burr relief is provided on the mating surface of the upper mold 48 and the lower mold 50 so that burr does not occur, and the diameter dimensions of the main body 42 and the shaft portion 44 are designed to be within the tolerance. There is also a mold.

However, when the burr relief is provided, the cross-sectional shape of the main body 42 and the shaft portion 44 does not become a perfect circle, and the surface finish in the mold cavity of the mold provided with the burr relief is very difficult, and the molded product is formed. Surface accuracy is poor.

[0007]

SUMMARY OF THE INVENTION In consideration of the above facts, it is an object of the present invention to provide a roller molding die that does not generate a parting line and burrs in the axial direction on the circumferential surface of the roller. .

[0008]

According to a first aspect of the present invention, there is provided a roller comprising a cylindrical main body and shaft portions provided at both ends of the main body. It is characterized by the absence of axial burrs on the part or the whole.

A roller forming die according to a second aspect of the present invention is a roller forming die for manufacturing a roller including a cylindrical main body and shaft portions provided at both ends of the main body. A first mold in which a stepped cylindrical mold hole for integrally molding one of the main body and the main body is formed, and a cylindrical mold hole for forming the other side of the shaft portion in a face-to-face relationship with the first mold. And a second die formed.

According to a third aspect of the present invention, there is provided a roller forming die which comprises a roller having a cylindrical main body and shaft portions provided at both ends of the main body, and two metal molds having semi-cylindrical die holes. In a roller molding die in which molten resin is poured into a cylindrical cavity that is face-matched to a mold, and is taken out after cooling, the end face is closed into the cavity that is face-matched and made into a cylindrical shape. It is characterized in that a core having a cylindrical mold hole for molding one side is movably arranged.

[0011]

In the roller according to the first aspect, since there is no burr on the surface of the roller body and the shaft portion in the axial direction, the surface accuracy of the circumferential surface is excellent.

In the roller molding die according to claim 2,
A roller in which a cylindrical main body and shafts provided at both ends of the main body are integrated is manufactured.

A stepped cylindrical mold hole for integrally molding one of the shaft part and the main body is formed in the first mold, and the second mold is
A cylindrical mold hole for molding the other of the shaft portions is formed.

The first mold and the second mold are face-to-face, the molding material is injected into the cavity, and after cooling, the roller as a molded product is taken out.

Here, the parting line and the burr are
Since the first mold and the second mold are generated at the end peripheral surface of the main body, which is a mating surface, and the joint portion between the main body and the shaft portion, the roller having excellent surface accuracy on the circumferential surfaces of the main body and the shaft portion. Can be molded. Since the parting line and the position where the burr is generated are not particularly problematic in terms of the function of the roller, there is no need for post-finishing.

Further, since it is not necessary to form a burr escape for escaping the burr, it is possible to manufacture a roller having an ideal circular cross section.

In the roller molding die according to claim 3,
The core moves in the cavity which is made into a cylindrical shape by face-to-face matching. The core has a cylindrical mold hole whose end face is closed to mold one of the shaft portions. Therefore, no burr is generated in the axial direction of the surface of the shank formed by the core, and the core moves in the demolding direction after the molten resin has cooled. make it easier.

[0018]

EXAMPLE As shown in FIG. 1, a roller molding die 10 according to the first embodiment is composed of a fixed die 12 and a movable die 14. The movable mold 14 has a small cylindrical shaft hole 20 whose end is closed to form the shaft portion 18 of the roller 16, and a parting with the fixed mold 12 which communicates with the shaft hole 20. A large cylindrical main body mold hole 2 whose surface is open to form the main body 22
4 are formed. An extruding pin (not shown) is provided at the end of the shaft-shaped hole 20, and the roller 16 after molding is provided.
Is pushed out in the axial direction.

On the other hand, the fixed die 12 is formed with a small cylindrical shaft die hole 28 for forming the shaft portion 26 of the roller 16 by opening a parting surface P with the movable die 14. At the end of the shaft-shaped hole 28, a gate 30 for injecting a molten resin is provided. As described above, by providing the gate 30 on the end surface of the shaft portion 26, the post-finishing of the gate 30 is simplified, and the quality of the roller 16 is not affected.

The gate 30 is connected to the spool 34 by a runner 32 as a runner. In this spool 34,
A nozzle (not shown) is connected and molten resin is injected.

Next, a method of manufacturing the roller 16 will be described.
The movable mold 14 and the fixed mold 12 which are positioned and connected by a guide rod (not shown) are clamped, and molten resin is passed from the spool 34 through the runner 32 and the gate 30 to the main mold hole 24 and the shaft mold holes 20 and 28. Inject into the composed cavity. The molten resin that has entered the cavity expels the air and fills the cavity. Here, the air in the cavity is exhausted from a degassing mechanism (not shown) provided on the parting surface P of the movable mold 14 and the fixed mold 12. It should be noted that this degassing mechanism is preferably provided at a position farthest from the gate for injecting the molten resin into the cavity, and when a degassing hole is provided,
Although the pore diameter varies depending on the fluidity of the resin, it is generally large enough to allow the gas to pass and the resin not to pass.

Next, when the cooling of the molten resin is completed, the moving mold 14 is retracted to the moving side. When the movable die 14 is guided by the guide rod and retracts to a predetermined position, the push pin is relatively pushed out toward the fixed die 12, and the body die hole 24 and the shaft die hole 20 of the movable die 14 roll from the roller. 16 is projected.

In the roller 16 manufactured in this manner, parting lines and burrs are generated on the peripheral surface of the end of the main body 22 (arrow A) and the joint between the main body 22 and the shaft portion 26 (arrow B). However, this part does not pose any particular problem in terms of the function of the roller, so that it is not necessary to finish it.

Next, a roller molding die according to the second embodiment will be described. As shown in FIG. 2, the roller molding die 60 includes a fixed die 62 and a movable die 64.
The fixed mold 62 and the movable mold 64 are formed with a stepped semi-cylindrical mold hole 74 for molding one shaft portion 68 of the roller 66 and the main body 70. A recess 76 extending to one end of the mold hole 74 for molding the main body 70 is provided on the parting surface P above the mold hole 74. The concave portion 76 forms an opening into which the core 72, which is a rectangular block, can be inserted when the fixed mold 62 and the movable mold 64 are face-to-face. The core 72 is formed with a cylindrical shaft-shaped hole 78 whose end is closed along the movement direction (direction of arrow A) so as to mold the other shaft 80 of the roller 66.

Next, a method of manufacturing the roller 66 will be described.
The tip of the core 72 is inserted until it contacts the bottom surface 76A of the recess 76, and the fixed mold 62 and the movable mold 64 are clamped. As a result, the cavity of one shaft portion 80 of the roller 66 is formed in the core 72 by the shaft die hole 78, and the cavity of the other shaft portion 68 and the main body 70 is formed by the die hole 74.

Here, after the molten resin is poured and cooled, the mold is opened and the roller 66 is taken out. At this time, the roller 66 is taken out by moving the core 72 away from the mold hole 74. It will be easy. Further, since the shaft 80 is molded by the shaft-shaped hole 78 and no burr is generated in the axial direction of the surface, the shaft having excellent surface accuracy can be manufactured.

As described above, the necessity of improving the surface accuracy of one shaft portion of the roller arises when a groove is formed in the other shaft portion. That is, since the shaft portion in which the groove is formed cannot be die-cut in the axial direction, the shaft portion is formed by dividing the die. At this time, by improving the surface accuracy of one of the shaft portions, it is possible to improve the sealing characteristic of the fitting portion.

Incidentally, the roller molding die 1 according to the present embodiment.
When the roller 16 manufactured with 0 is used as a magnet roller arranged in, for example, a copying machine, the following functions are exhibited.

Although the shaft portion of the roller is supported by the bearing portion, it is necessary to form the shaft portion within the fitting tolerance in order to reduce the rotational play of the roller. However, since the shaft portion of the roller according to the present embodiment has a perfect circular shape, the above tolerance can be easily cleared.

The magnet roller is arranged in the copying machine in a state of being covered with the developing sleeve, but both ends of the magnet roller and the developing sleeve are oil-sealed so that the toner powder for developing is not mixed into the developing sleeve. To be done.
This magnet roller has no parting line or burr on its peripheral surface, so the main body and shaft are perfectly circular,
The sealing effect is improved.

An oil seal is also provided on the shaft portion so that the toner powder does not leak out of the toner hopper.
Since this shaft portion has a perfect circular shape and is excellent in surface accuracy, it is possible to completely shut off the toner hopper from the outside.

[0032]

Since the present invention has the above-mentioned structure, no parting line or burr is generated in the axial direction on the circumferential surface of the roller.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a roller molding die according to a first embodiment.

FIG. 2 is an exploded perspective view of a roller molding die according to a second embodiment.

FIG. 3 is an exploded perspective view of a conventional roller molding die.

[Explanation of symbols]

 12 Fixed Mold (2nd Mold) 14 Moving Mold (1st Mold) 20 Shaft Mold Hole 24 Main Body Mold Hole 28 Shaft Mold Hole 62 Fixed Mold 64 Moving Mold 72 Core 76 Recess 78 Shaft Mold Hole

Claims (3)

[Claims] 1. A roller comprising a columnar main body and shaft portions provided at both ends of the main body, wherein the shaft portion and the surface of the main body are partially or entirely free from axial burrs. Characterized roller. 2. A roller molding die for manufacturing a roller comprising a columnar main body and shafts provided at both ends of the main body, wherein one of the shafts and the main body are integrally molded. A first mold having a stepped cylindrical mold hole formed therein; and a second mold having a cylindrical mold hole formed to face the first mold to mold the other of the shaft portions. A mold for forming a roller, which has. 3. A roller composed of a cylindrical main body and shafts provided at both ends of the main body is made into a cylindrical shape by bringing two molds having semi-cylindrical mold holes into surface contact with each other. In the mold for roller molding that injects the molten resin into the cavity and takes it out after cooling, a cylindrical mold hole for molding one of the shaft parts is formed by closing the end face into the cavity that is made into a cylindrical shape by face-to-face matching. A roller molding die, wherein the formed core is movably arranged.