JP3935458B2 - Molding device - Google Patents

Description

  The present invention relates to a molding apparatus for molding a tube or a roller used as a fixing or transfer belt used in an image fixing apparatus or an image transfer apparatus such as an electrophotographic copying machine or a printer.

This type of tube or roller is formed in a single layer or a plurality of layers, but it is required to reduce the thickness and to make the thickness uniform in response to a demand for high thermal conductivity and high image quality in an electrophotographic copying machine or the like.
For example, liquid rubber is injected through a casting nozzle between a core serving as an axial center and a cylindrical mold that is coaxially fitted to the outer periphery of the core, and then the liquid rubber is heat-cured and coated. An apparatus for forming a fixing roller as a layer is known (for example, see Patent Document 1). Using such a molding apparatus as it is, it is practically impossible to mold a highly accurate tube or roller that is thin and uniform in thickness. Therefore, in order to mold a tube or roller having a thin wall and a uniform thickness, the above molding apparatus was modified and a tube or roller molding apparatus as shown in FIGS.

The molding apparatus shown in FIG. 2 holds an inner wall cylindrical mold 36 having journal portions 36A at both ends, an outer wall cylindrical mold 37 arranged coaxially, both ends of both cylindrical molds 36, 37, and a lower lid 39. , 33 and the like. During roller molding, the inner wall cylindrical mold 36 also serves as a roller core shaft.
The lower lid 33 is configured by combining a lid body 33A with a support cylindrical body 33B. A casting nozzle 31 is attached to the center of the lid body 33A. Tapers 40 and 41 are provided on the outer peripheral surfaces of both ends of the outer wall cylindrical mold 37, and the inner peripheral surfaces of the upper and lower lid bodies 39 and 33 in contact therewith are also provided with a taper. The inner wall cylindrical mold 36 is positioned by a core 34 disposed in the support cylindrical body 33 </ b> B of the lower lid body 33. That is, double circular grooves into which the lower journal part 36A of the inner wall cylindrical mold 36 can be inserted are provided on the upper surface of the core 34, and the journal part 36A of the inner wall cylindrical mold 36 is fitted into these grooves. Is positioned. The core 34 also has a role of forming a flow path for the liquid rubber, and a plurality of grooves 38 are provided on the outer peripheral surface of the inverted truncated conical cylindrical body as shown in FIG. It has been configured.

The molding apparatus configured in this manner injects liquid rubber into the vertical space between the inner wall cylindrical mold 36 and the outer wall cylindrical mold 37, which are coaxially fitted, via the casting nozzle 31, and thereafter Then, the liquid rubber is heated and cured to disassemble each part such as a mold, thereby obtaining a tube or a roller.
The coaxial assembly accuracy of the inner wall cylindrical mold 36 and the outer wall cylindrical mold 37 for uniforming the wall thickness is such that the contact portions 40 and 41 between the cylindrical molds 36 and 37 and the upper and lower lid bodies 39 and 33 are tapered. And by tightening the fitting tolerance of the journal portion 36A of the inner wall cylindrical mold.

3 includes an inner wall cylindrical mold 56 having a journal portion 56A at the upper end, an outer wall cylindrical mold 57 disposed coaxially, and upper and lower lids 59 that hold both ends of both cylindrical molds 56, 57. 52, upper and lower spacers 60, 55, and the like.
The lower lid body 52 is configured by combining a lid body 52A with a support cylindrical body 52B. A casting nozzle 51 is attached to the center of the lid main body 52A. The upper spacer 60 has a cylindrical shape, and as shown in FIG. 3B, a plurality of claws 61 are provided around the lower end surface. A taper is provided on the outer surface of each claw 61. A taper is also provided on the inner peripheral surface of the upper end portion of the outer wall cylindrical mold 57 in contact with the taper of each claw 61. The lower spacer 55 has a downward conical shape, and, as shown in FIG. 3C, a plurality of claws 54 are provided around the upper end surface. A taper is provided on the outer surface of each claw 54. A taper is also provided on the inner peripheral surface of the lower end portion of the outer wall cylindrical mold 57 in contact with the taper of each claw 54.

The outer wall cylindrical mold 57 and the inner wall cylindrical mold 56 are positioned by upper and lower lids 59 and 52 and upper and lower spacers 60 and 55.
The lower spacer 55 also has a role of forming a flow path for liquid rubber, and has a configuration in which a plurality of grooves 58 are provided on the outer peripheral surface.
The molding apparatus configured as described above injects liquid rubber into the space between the inner wall cylindrical mold 56 and the outer wall cylindrical mold 57 that are coaxially fitted via the casting nozzle 51, and then A tube or a roller is obtained by heat-curing the liquid rubber and disassembling each part such as a mold.
The coaxial assembly accuracy of the inner wall cylindrical mold 56 and the outer wall cylindrical mold 57 to make the thickness uniform is as follows: the cylindrical molds 56 and 57, the upper and lower lids 59 and 52, and the upper and lower spacers 60 and 55. Obtained by each contact portion with the nail.
JP-A-5-329848

By the way, the above technique has the following problems to be solved.
The molding apparatus shown in FIG. 2 has been found to have the following difficulties. That is, in the taper contact, the contact pressure is likely to be imbalanced, and a frictional force is generated, so that it is difficult to obtain a geometrically expected coaxiality. Further, in order to secure the assembly accuracy by the fit tolerance, it is necessary to make the fit tolerance strict and to make the fit section long. However, in this case, so-called galling is likely to occur at the time of assembly, and the assemblability is significantly lowered.

As shown in the following example, the required assembly accuracy cannot be obtained in a realistic fit tolerance and section in consideration of assembly.
That is, as shown in FIG. 2A, when the fitting clearance 20 μm between the upper end journal portion 36 A of the inner wall cylindrical mold 36 and the upper lid 39, the fitting section A is 30 mm, and the constraining cylinder length B is 300 mm. Simply, the geometrical maximum axis deviation reaches 0.2 mm.
Further, since the upper and lower lid bodies 39 and 33 serve as a lid for restraining both the cylindrical dies 36 and 37 and a fastening member for positioning, a large structure is obtained. Due to the small force or moment, the two cylindrical dies 36 and 37 may be deformed and the assembly accuracy may be deteriorated.

  Moreover, it has been found that the molding apparatus shown in FIG. 3 has the following difficulties. That is, in order to make the thickness uniform, the upper and lower spacers 60 and 55 are inserted between the outer wall cylindrical mold 57 and the inner wall cylindrical mold 56 so as to maintain the distance between the inner wall cylinder and the outer wall cylinder. Is. For this reason, the contact surfaces for maintaining a space between the outer wall cylindrical mold 57 and the inner wall cylindrical mold 56 are the inner surface of the outer wall cylindrical mold 57, the outer surfaces of the claws 61 and 54 of the upper and lower spacers 60 and 55, The outer surface of the cylindrical mold 56, the inner surfaces of the upper and lower spacers 60 and 55, and four surfaces exist. For this reason, the assembly accuracy is a stacking of the processing accuracy of four surfaces, and is deteriorated as compared with the case where there is a single contact surface. Further, the posture after the spacer assembly is likely to vary, and the assembly accuracy may be varied.

  An object of this invention is to provide the shaping | molding apparatus which can shape | mold the highly accurate tube or roller which is thin and has uniform thickness.

The present invention adopts the following configuration in order to solve the above points.
<Configuration 1>
An inner wall cylindrical mold, an outer wall cylindrical mold disposed coaxially on the outer side of the inner wall cylindrical mold, and the both cylindrical molds fitted to each end of the inner wall cylindrical mold and the outer wall cylindrical mold An upper lid and a lower lid, and a liquid rubber inlet provided in the lower lid for injecting liquid rubber between the inner wall cylindrical mold and the outer wall cylindrical mold, and the inner wall cylindrical mold A molding apparatus, wherein a plurality of protrusions are provided radially on the periphery of each end portion of the mold and the opposing surface of the outer wall cylindrical mold.

Liquid rubber is injected into a space between the inner wall cylindrical mold and the outer wall cylindrical mold arranged coaxially and cured to form a molded layer to be a tube or a roller. As the liquid rubber, a rubber elastic material having heat resistance such as silicone rubber and fluorine rubber is used.
According to Configuration 1, since the contact surfaces between the plurality of protrusions provided at the end portions of the inner wall cylindrical mold and the outer wall cylindrical mold and both the cylindrical molds are small, the sliding sliding distance is short and the assemblability is impaired. Absent. Further, the contact surfaces for determining the thickness of the molding layer for maintaining the distance between the two cylindrical molds are only two surfaces, that is, the front end surfaces of the plurality of protrusions and the peripheral surfaces of the two cylindrical molds in contact with the front end surfaces. Therefore, the assembly processing accuracy is hardly deteriorated. Configuration 1 is to mold a high-precision tube or roller with a small thickness and small fluctuation in thickness, with an outer diameter of 10 mm or more, a thickness of 0.1 to 0.5 mm, and a thickness variation of about ± (10 to 20) μm. Suitable for.

<Configuration 2>
In the molding apparatus according to Configuration 1, the tip of the protrusion provided on the inner wall cylindrical mold is in contact with the inner peripheral surface of the outer wall cylindrical mold, and the tip of the protrusion provided on the outer wall cylindrical mold is A molding apparatus characterized by being in contact with an outer peripheral surface of an inner wall cylindrical mold.

  The protrusions provided on the inner wall cylindrical mold and the protrusions provided on the outer wall cylindrical mold are provided at respective end portions of the inner wall cylindrical mold and the outer wall cylindrical mold arranged coaxially.

<Configuration 3>
3. The molding apparatus according to Configuration 1 or 2, wherein the protrusions are provided intermittently at least at two positions of each end of the inner wall cylindrical mold and the outer wall cylindrical mold.

  The protrusions at each end of the inner wall cylindrical mold and the outer wall cylindrical mold are provided at two or more locations, but the dimensional accuracy of the tube or roller increases as the number increases to some extent. However, since the space between the lower protrusions serves as a flow path for the liquid rubber, the number and size of the protrusions are determined in consideration of the viscosity of the liquid rubber, the injection workability, and the like.

  Hereinafter, embodiments of the present invention will be described using specific examples.

Hereinafter, embodiments of the present invention will be described using specific examples.
Fig.1 (a) is sectional drawing which shows one Example of the shaping | molding apparatus of this invention. FIG.1 (b) is a cross-sectional view which follows the BB line of the same (a), (c) is a cross-sectional view which follows the CC line of the same (a).
In FIG. 1A, the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17 are arranged coaxially. The inner wall cylindrical mold 16 has journal portions 16A on both end faces. A plurality of protrusions 20 are provided radially on the outer peripheral surface of the upper end portion of the inner wall cylindrical mold 16. These protrusions 20 are in contact with the inner peripheral surface of the upper end portion of the outer wall cylindrical mold 17 and restrain the radial movement of the outer wall cylindrical mold 17. A plurality of protrusions 18 are radially provided on the outer peripheral surface of the lower end portion of the outer wall cylindrical mold 17. These protrusions 18 are in contact with the outer peripheral surface of the lower end portion of the inner wall cylindrical mold 16 and restrain the radial movement of the inner wall cylindrical mold 16.

Further, as shown in FIGS. 1B and 1C, these protrusions 18 and 20 are provided intermittently at almost regular intervals, and are provided between the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17. A gap is formed at an interval. The size of the gap in the radial direction is the thickness of the tube to be molded. Between the plurality of protrusions 18 provided at the lower end portion of the outer wall cylindrical mold 17 is a flow path for liquid rubber, which will be described later, the number and width of the protrusions 18 in the circumferential direction are determined by the viscosity of the liquid rubber. . The length of the projection in the axial direction is several mm or less.
The protrusions 18 and 20 are alternately provided on the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17. That is, although different from that shown in FIG. 1A, when one projection 20 is provided at the upper end of the inner peripheral surface of the outer wall cylindrical mold 17 or in the vicinity of the upper end, the other projection 18 is It is provided at the lower end of the outer peripheral surface of the mold 16 or near the lower end.

  An upper lid 19 and a lower lid 12 are fitted to both ends of the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17, respectively. A core 14 is fitted into a journal portion 16A at the lower end of the inner wall cylindrical mold 16. The core 14 has a role of forming a flow path for the liquid rubber together with the lower lid 12. The upper lid 19 is provided with an inner hole having the same inner diameter as the outer diameter of the end of the outer wall cylindrical mold 17 and an inner hole into which the journal part 16A of the outer wall cylindrical mold 17 is fitted. . The lower lid 12 is a combination of a cylindrical body 12B having the same inner diameter as the outer diameter of the end of the outer wall cylindrical mold 17 and a lid body 12A fitted to one end of the cylindrical body 12B. The casting nozzle 11 is connected to the lid body 12A, and a through hole is provided at the center thereof. This through hole serves as a liquid rubber injection port for injecting the liquid rubber.

  The molding apparatus configured in this manner injects liquid rubber into the vertical space between the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17 fitted coaxially through the casting nozzle 11, and thereafter Then, the liquid rubber is heated and cured to disassemble each part such as a mold, thereby obtaining a tube or a roller. As the liquid rubber, a rubber elastic material having heat resistance such as silicone rubber and fluorine rubber is used.

  According to the molding apparatus having the above configuration, there are the following advantages, and a rubber tube having a thickness variation of ± (10 to 20) μm can be molded. That is, since the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17 have a simple configuration in which the distance between them is directly constrained, the assembly accuracy is not deteriorated, and the inner wall cylindrical mold 16 and the outer wall cylinder are more highly accurate. The mold 17 can be assembled. Further, since the contact portion is the tip surface of the protrusions 18 and 20, the restraining section is short, and the assembling and sliding distance of the restraining section portion can be shortened at the time of assembling. Further, since the inner wall cylindrical mold 16 and the outer wall cylindrical mold 17 are in direct contact with each other and depend only on the processing accuracy of the two surfaces, the assembly accuracy is further improved as compared with the structure using the spacer. In addition, a clamping force is applied in advance in the mold axial direction to resist fluid pressure at the time of casting or injection, but there is no stress associated with this in the direction of degrading assembly accuracy.

FIG. 4 is a view showing a wall thickness distribution of a tube molded under the following conditions by the molding apparatus of the present invention.
That is, a tube having an outer diameter of 60 mm, a wall thickness of 330 μm, and a length of 300 mm was molded. The thickness of this tube was measured at 48 data per tube at intervals of 45 degrees in the circumferential direction and at an interval of 60 mm in the axial direction, and a total of 288 measurement results from 6 tubes were distributed. This is shown in FIG. From this measurement, it was found that the average tube thickness was 330 μm and the standard deviation was 3.6 μm.

It is a figure which shows the shaping | molding apparatus of this invention, (a) is a longitudinal cross-sectional view of the whole apparatus, (b) is a cross-sectional view which follows the BB line of (a), (c) is CC of (a). It is a cross-sectional view along a line. It is a figure which shows the conventional shaping | molding apparatus, (a) is a longitudinal cross-sectional view of the whole apparatus, (b) is a top view of a core. It is a figure which shows the other conventional shaping | molding apparatus, (a) is a longitudinal cross-sectional view of the whole apparatus, (b) is a top view of an upper spacer, (c) is a top view of a lower spacer. It is a characteristic view which shows the thickness distribution condition of the tube shape | molded by the shaping | molding apparatus of this invention.

Explanation of symbols

11 Casting nozzle 12 Lower lid 14 Core 16 Inner wall cylindrical mold 17 Outer wall cylindrical mold 18, 20 Protrusion 19 Upper lid

Claims (2)

An inner wall cylindrical mold,
An outer wall cylindrical mold disposed coaxially on the outer side of the inner wall cylindrical mold;
An upper lid and a lower lid that are fitted to respective end portions of the inner wall cylindrical mold and the outer wall cylindrical mold to fix the two cylindrical molds;
A liquid rubber injection port provided on the lower lid body and for injecting liquid rubber between the inner wall cylindrical mold and the outer wall cylindrical mold;
A plurality of protrusions are provided radially on the outer peripheral surface of the upper end portion of the inner wall cylindrical mold and the inner peripheral surface of the lower end portion of the outer wall cylindrical mold, and the tips of the protrusions provided on the inner wall cylindrical mold are A molding apparatus characterized in that it abuts on the inner peripheral surface of the outer wall cylindrical mold, and the tip of the projection provided on the outer wall cylindrical mold abuts on the outer peripheral surface of the inner wall cylindrical mold. The molding apparatus according to claim 1,
  2. The molding apparatus according to claim 1, wherein the protrusions are provided intermittently at least at two locations on each end of the inner wall cylindrical mold and the outer wall cylindrical mold.

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