JPH08207165A - Manufacture of curved tube of rubber - Google Patents

Abstract

PURPOSE: To obtain a manufacture of a curved tube of a rubber which dispenses with jacket treatment and others. CONSTITUTION: An unvulcanized raw rubber tube 20 extruded from an extruder 1 is passed through a microwave vulcanizing furnace and a radiation heat furnace 6 to be semivulcanized, and after the semivulcanized tube is cut in prescribed dimensions by a automatic cutter 12, it is put on a mandrel 13 and subjected to main vulcanization. Then a curved tube 50 of a rubber in a prescribed shape is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a rubber bent tube.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 4-201323 discloses a resin mandrel covered with an unvulcanized rubber tube and a resin or lead coating around the mandrel (hereinafter referred to as a jacket treatment), followed by partial vulcanization. A method of manufacturing a bent tube having a predetermined shape at the same time as removing the outer cover by cutting the piece into a predetermined length and then covering the bent mandrel with a main vulcanization is shown.

In addition, in Japanese Utility Model Publication No. 55-113223,
An apparatus for rapidly raising the extruded rubber to a vulcanization temperature by microwave and then performing a main vulcanization in a hot air oven is shown.

[0004]

By the way, in order to manufacture a bent tube having a smaller diameter, in order to prevent thinning on the outer side of the corner portion and wrinkles on the inner side, various methods are required prior to the main vulcanization as in the conventional example. A process is needed.

However, in the method of performing the resin mandrel and the jacket treatment as in the above-mentioned conventional example, the number of steps is complicated and the molding cycle is lengthened, so that the cost is increased and the jacket is melted. There is a problem that the working environment is deteriorated. Therefore, it is desired to provide a manufacturing method capable of omitting the outer coating process and the resin mandrel and rapidly processing.

[0006]

In order to solve the above-mentioned problems, the present application discloses a step of extruding an unvulcanized rubber tube made of natural rubber or synthetic rubber without an outer cover, and a raw rubber tube for the microwave vulcanization furnace. The process of semi-vulcanization by passing it through a radiant heat furnace, and then cutting this semi-vulcanized tube to an appropriate length and covering it with a bending mandrel formed in a predetermined curved shape in advance for main vulcanization And a step of performing.

[0007]

When the unvulcanized rubber tube is extruded and immediately passed through the microwave vulcanizing furnace, it is heated up rapidly to a predetermined vulcanizing temperature due to internal heating. Then, this is continuously passed through a radiant heat furnace to heat it from the outside and bring it into a semi-vulcanized state.

[0008] In this state, since it is possible to make a habit, it can be bent into a predetermined shape without causing inconvenient deformation inside and outside the bent portion. Therefore, after being cut to a predetermined size, the mandrel is covered and main vulcanization is performed.

As a result, a bent rubber tube having a predetermined shape can be obtained, and by using a microwave vulcanizing furnace and a radiant heating furnace together, the jacket treatment and the resin mandrel in the semi-vulcanizing step required in the conventional example can be performed. It is unnecessary and can be semi-vulcanized in an extremely short time.

For this reason, the conventional complicated process and relatively long molding cycle can be changed to a simple process and short molding cycle, and as a result, the molding line can be shortened.

[0011]

EXAMPLE FIG. 1 is a schematic view showing a molding line. First, the unvulcanized raw rubber tube 20 is extruded by the extruder 1. The outer diameter measuring machine 2 measures the outer diameter of the raw rubber tube 20 and feedback-controls the operation of the extruder 1.

Subsequently, the unvulcanized raw rubber tube 20 is sent through the take-up conveyor 3 into the microwave vulcanizing furnace 4, where it is internally heated by microwave heating. In this embodiment, the line speed is 15 m / min throughout.

An infrared thermometer 5 is provided at the exit of the microwave vulcanization furnace 4 to measure the surface temperature of the unvulcanized raw rubber tube 20. If the temperature reaches a predetermined temperature, heating in the microwave vulcanization furnace 4 is performed. Is judged to be sufficient.

The unvulcanized raw rubber tube 20 is subsequently conveyed into the radiant heating furnace 6 which is constructed as a hot air furnace, where it is heated from the outside by hot air to become a semi-vulcanized tube 30.

The semi-vulcanized tube 30 discharged from the radiant heat furnace 6 is taken up by the inclined conveyor 7 and then rapidly cooled in the spiral cooling device 8. The inclined conveyor 7 and the spiral cooling device 8 both contribute to shortening the molding line.

After cooling, the semi-vulcanized tube 30 is subjected to predetermined printing such as company name and product code on the outer peripheral portion by the printing machine 9, and after being measured by the outer diameter measuring machine 10, sent to the automatic cutting machine 12 by the take-up conveyor 11. And cut into a predetermined size here.

The cut tube 40 that has been cut is covered on the mandrel 13 and sent to the vulcanization furnace 14 which is a hot air oven to be fully vulcanized. After that, when taken out from the vulcanizing furnace 14 and removed from the mandrel 13, a rubber bent tube 50 fixed in a predetermined shape is obtained.

Next, the details of each part will be described. The unvulcanized raw rubber tube 20 has a laminated structure made of synthetic rubber, the outer layer 21 is a CSM rubber, and the inner layer 22 is a chloroprene rubber when used for gas and NBR when used for oil, etc. Combine appropriately.

It should be noted that a single layer or three or more layers may be used, and natural rubber may be used. The inner diameter is 13m.
A small diameter of m or less can be molded. This inner diameter of 13 mm is a critical dimension at which the mandrel cannot be mounted in the case of unvulcanized raw rubber. However, it is a matter of course that a diameter larger than this can be molded.

The microwave vulcanizing furnace 4 can be adjusted in various ways such as frequency and output, but in this embodiment, it is 15 K at 2450 MHz.
w is used. Further, the total length is 3 m, and under these conditions, the surface temperature of the unvulcanized raw rubber tube 20 at the outlet of the microwave vulcanization furnace 4 is the vulcanization temperature 24.
It is set to reach 0 ° C.

The radiant heating furnace 6 is an oil burner type hot air furnace, and the temperature inside the furnace is set to 240 ° C. The radiant heat furnace 6 has a total length of about 4 m, and a continuous conveyor is folded back in three stages inside. However, the length and the number of internal stages of the radiant heat furnace 6 can be freely changed. Further, the heating means can also be irradiated with infrared rays.

By the microwave vulcanization furnace 4 and the radiant heat furnace 6,
At the outlet of the radiant heat furnace 6, the unvulcanized raw rubber tube 2
0 is semi-vulcanized into a semi-vulcanized tube 30.

An example of the physical properties of this semi-vulcanized tube 30 is shown in FIG. Figure 2 shows the change over time in the shrinkage rate and the habit angle.
In this embodiment, the range from the intersection of both curves to the shrinkage rate of 0 is defined as the range of semi-vulcanization.

The squeeze angle means an angle at which a bent state can be fixed, and the angle increases as vulcanization progresses.
It is indicated by a broken line in the figure. Further, the shrinkage ratio is the ratio of volume reduction due to vulcanization, and becomes smaller as vulcanization progresses, and is shown by the solid line in the figure.

The rubber bending tube 50 is a tube having an inner diameter of 7.3 mm and a length of 12.5 cm obtained in this way, and both the inner peripheral side 51 and the outer peripheral side 52 of the curved portion are
No inconvenient deformed parts such as wrinkles or thin parts are generated.

As described above, according to this embodiment, since the semi-vulcanization step is placed before the bending step, it is possible to mold a thin tube which has been difficult to mold by the conventional unvulcanized rubber. The range varies depending on various conditions, but in the case of the above-mentioned conditions, a bent tube having a small inner diameter of about 3.5 mm to 13 mm can be molded.

Moreover, the microwave vulcanization furnace 4 and the radiant heat furnace 6
Since the semi-vulcanization is performed by the combined use of (1) and (2), it is possible to omit the conventional coating treatment and resin mandrel. Therefore, the molding is simplified and the molding cycle is shortened, so that the cost can be reduced and the molding line can be shortened.

Assuming that the radiant heat furnace alone is used to perform the half-vulcanization treatment similar to this embodiment, the radiant heat furnace line for semi-vulcanization is expected to be about 50 m, which can be shortened to about 1/10. Also, the molding cycle can be improved from about 600 seconds to about 60 seconds.

[Brief description of drawings]

FIG. 1 is a diagram showing a molding line of an example.

Fig. 2 Physical properties of semi-vulcanized rubber

[FIG. 3] Same as above

[Fig. 4] Same as above

[Explanation of symbols]

1: Extruder, 4: Microwave vulcanizing furnace, 6: Radiant heating furnace, 12: Automatic cutting machine, 13: Mandrel, 14: Vulcanizing furnace, 20: Unvulcanized rubber tube, 40: Cut tube (semi-vulcanized) ), 50: Curved rubber tube (product)

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[Procedure amendment]

[Submission date] May 17, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing a molding line of an example.

Fig. 2 Physical properties of semi-vulcanized rubber

[Explanation of Codes] 1: Extruder, 4: Microwave vulcanizing furnace, 6: Radiant heating furnace, 12: Automatic cutting machine, 13: Mandrel, 14: Vulcanizing furnace, 20: Unvulcanized rubber tube, 40: Cut Tube (semi-vulcanized), 50: Rubber bent tube (product)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29C 53/82 9268-4F 53/84 9268-4F F16L 9/12 // B29K 21:00 105: 24 B29L 23:00 (72) Inventor Nobuyuki Tsujioka 880-1, Myohoji, Anno-cho, Aki-gun, Mie Yamashita Rubber Co., Ltd. Mie factory

Claims (1)

[Claims] 1. A step of extruding an unvulcanized rubber tube without an outer cover, and a step of passing the unvulcanized rubber tube through a microwave vulcanizing furnace and then by passing it through a radiant heat furnace for semi-vulcanization. And a step of cutting the semi-vulcanized tube into an appropriate length, covering it with a bending mandrel formed in a predetermined curved shape in advance, and performing main vulcanization, and producing the rubber bent tube.