JPH081829A - Manufacture of roller - Google Patents

Abstract

PURPOSE:To provide a method for efficiently manufacturing, with high dimensional precision, a roller consisting of resin having support axes arranged at both ends in the axial direction of a cylindrical roller body and a gear arranged on at least one support axis. CONSTITUTION:A mold 8 for forming a cavity 7 having an inside shape correlating with an outside shape of a roller 1 is prepared. A cylindrical pipe 15 which forms an outer peripheral face of a roller body 2 is inserted into the cavity 7. A resin 16 is injected into the cavity 7 so as to make an unfilled part 17. A gas 18 is injected into the resin 16 so as to fill the unfilled part 17 with the resin 16. As the outer peripheral face of the roller body is formed by the previously prepared pipe, a roller having a hollow structure can be efficiently manufactured with excellent dimensional precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a roller which is provided with a gear at least at one end and which is substantially made of resin.

[0002]

2. Description of the Related Art FIG. 2 is a perspective view showing the outer appearance of a roller 1 which is of interest to the present invention. This roller 1
Is currently used as a roller for feeding photographic paper in a photo printing apparatus. Such a roller 1
Is composed entirely of resin so that it does not corrode on contact with the drug.

The roller 1 is provided with a cylindrical roller body 2, which projects from both ends of the roller body 2 in the axial direction.
Support shafts 3 and 4 are provided. Gears 5 and 6 are provided on the support shafts 3 and 4, respectively.

In order to efficiently manufacture such a roller 1, the applicant of the present application filed Japanese Patent Application No. 4-16100.
Japanese Patent Laid-Open No. 5-208460 proposes the following roller manufacturing method. That is,
A mold for integrally molding the entire roller 1 is prepared, resin is injected so that the unfilled portion remains in the mold, and then gas is injected into the resin so that the resin is spread over the unfilled portion. inject. As a result, the roller 1 integrally formed of resin can be efficiently manufactured. According to the roller 1 obtained in this way, since it has an integral structure, reliability with respect to strength is enhanced, and since it has a hollow structure, weight reduction can be achieved.

[0005]

However, when the roller manufacturing method described above is applied, the following problems may be encountered.

(1) When paying attention to the behavior of the resin in the mold, since the resin suddenly flows from the gate into the wide cavity, flow marks and jetting are likely to occur, and therefore the obtained roller is May cause poor appearance.

(2) Until the resin is cured in the cavity, the resin is kept in intimate contact with the mold by the gas pressure, so that a very high degree of adherence cannot be stably obtained, and as a result, it is obtained. The dimensional accuracy of the roller may be poor. For example, with respect to the roller body, its outer diameter is 3
In the case of 5 mm, a diameter tolerance of ± 0.05 mm is required, but only an accuracy of ± 0.2 mm may be obtained.

(3) If the roller has a long overall length, it may be relatively bent due to contraction during cooling for hardening the resin. For example, total length 20
A 0 mm roller is required to have an eccentricity tolerance of 0.15 mm or less, whereas an eccentricity of 0.5 to 0.6 mm may occur.

In order to solve such problems as much as possible, with respect to the above (1) and (2), for example, post-processing such as centerless polishing or cylindrical grinding is performed,
Regarding (3), although the cooling time is made longer and the straightening jig is used, both of them are not preferable because they lead to a decrease in roller productivity.

Therefore, an object of the present invention is to provide a method of manufacturing a roller which can manufacture a roller excellent in appearance and dimensional accuracy more efficiently.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a roller manufacturing method in which a support shaft is provided at both ends of a cylindrical roller body in the axial direction, and a gear is provided on at least one of the support shafts. In order to solve the above-mentioned technical problem, it is characterized by including the following steps.

(1) Preparing a mold for forming a cavity having an inner shape that correlates with the outer shape of the roller.

(2) Preparing a cylindrical pipe that provides the outer peripheral surface of the roller body.

(3) Inserting the pipe into the cavity. (4) A step of injecting resin so that an unfilled portion remains in the cavity into which the pipe is inserted.

(5) A step of injecting a gas into the resin so that the resin is spread over the unfilled portion.

[0016]

According to the present invention, appearance and dimensional accuracy are particularly problematic, and the outer peripheral surface of the roller body occupying the main part of the roller is provided by a cylindrical pipe prepared in advance.

[0017]

As described above, according to the present invention, it is possible to suppress deformation, particularly eccentricity, by the inherent rigidity of the pipe without causing a visual defect due to flow marks or jetting. Further, the smoothness of the outer peripheral surface of the pipe itself is maintained as it is in the obtained roller. From these facts, it is possible to efficiently manufacture a roller having an excellent appearance and dimensional accuracy and free from undesired deformation. Further, in order to obtain an excellent roller, post-processing or the like is not necessary, so that the factor that reduces productivity can be eliminated.

If the pipe inserted into the cavity needs to be processed, such processing may be performed in advance before the pipe is inserted into the cavity. By doing so, the processing becomes easier as compared with the case of processing after obtaining the roller.

Further, according to the present invention, the material of the pipe can be freely selected. Therefore, if necessary,
Only the outer peripheral surface of the roller body may be made of a material different from other portions, that is, in a extreme case, a material such as a metal different from resin. In this case, when the material of the pipe is inferior in compatibility with the resin to be injected, by providing an undercut etc. inside the pipe, the mechanical integrity between the pipe and the resin is further enhanced. You can

[0020]

1 shows an embodiment of the present invention.
This embodiment is intended for manufacturing the roller 1 shown in FIG.

As shown in FIG. 1A, a mold 8 for forming a cavity 7 having an inner shape that correlates with the outer shape of the roller 1 is prepared. The mold 8 is composed of, for example, a mold body 9 and slide cores 10 and 11. The mold body 9 is provided with a gate 12 and a runner 13 which communicate with the cavity 7. Further, a gas supply pipe 14 is provided so as to penetrate the slide core 11 and project into the cavity 7.

On the other hand, as shown in FIG. 1 (b), a cylindrical pipe 15 for providing the outer peripheral surface of the roller body 2 is prepared,
It is inserted into the cavity 7. 1 (b)-
In (e), the inner shape of the cavity 7 is illustrated, but the mold 8 is omitted. The pipe 15 is manufactured by, for example, extrusion molding, and cut to a desired length in order to match the length of the roller body 2. Although the material of the pipe 15 is arbitrary, it is preferable that the pipe 15 has excellent compatibility with the resin described later. For example, the pipe 15 is typically made of the same material as such resin. If the material of the pipe 15 and the resin are poor in compatibility, an undercut or the like may be provided on the inner peripheral surface of the pipe 15. Further, before being inserted into the cavity 7, the pipe 15 may be subjected to processing for making the outer diameter thereof into a desired dimension, if necessary.

Next, as shown in FIG. 1C, the runner 1
3 into the cavity 7 through the gate 3 and the gate 12
6 is shot. At this time, the unfilled portion 17 is left in the cavity 7.

Next, after the injection of the resin 16 is stopped, the gas 18 is injected from the gas supply pipe 14 as shown in FIG. 1 (d). The gas 18 causes the resin 16 to move in the cavity 7 so as to reach the unfilled portion 17, as shown in FIG.

In the state shown in FIG. 1 (e), the gas 1
After the supply of 8 is stopped and the resin 16 is cured, the molded product, that is, the roller 1 is taken out from the mold 8. At this time, the gas supply pipe 14 is pulled out from the roller 1 and the resin 16 is cut at the gate 12.

The roller 1 thus obtained is given a hollow structure by the action of the gas 18. FIG.
In (e), elements corresponding to those shown in FIG. 2 are designated by similar reference numerals. In addition, in FIG.
A boundary line between the pipe 15 and the resin 16 is shown by a broken line 19. The hole left as a result of the withdrawal of the gas supply pipe 14 may be closed if necessary.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing some representative steps included in a method for manufacturing a roller according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of a roller 1 which is of interest to the present invention.

[Explanation of symbols]

 1 Roller 2 Roller Body 3,4 Support Shaft 5,6 Gear 7 Cavity 8 Mold 12 Gate 14 Gas Supply Pipe 15 Pipe 16 Resin 17 Unfilled 18 Gas

Claims (1)

[Claims] 1. A method of manufacturing a roller, wherein a support shaft is provided at both ends of a cylindrical roller body in the axial direction, and a gear is provided on at least one of the support shafts. A mold for forming a cavity having an inner shape that correlates with, a cylindrical pipe that provides the outer peripheral surface of the roller body is prepared, the pipe is inserted into the cavity, and the pipe is inserted. A method for manufacturing a roller, comprising the steps of injecting a resin so that an unfilled portion remains in a cavity, and injecting a gas into the resin so that the unfilled portion is filled with the resin.