JPH03199035A - Manufacture of bent hose - Google Patents

Abstract

PURPOSE:To efficiently manufacture the bent hoses without employing mandrel by a method wherein tubular body in continuous form having fiber reinforcing layer, rubber external layer and thermoplastic resin layer covering in order name the outer periphery of rubber internal layer, the interior of which is filled with pressurized air, is subjected to bending operation and cut in pieces so as to install the resultant bent cut pieces in a form in order to be vulcanized and, after being removed from the form, frozen in order to separate the resin layer. CONSTITUTION:Under the condition that uncured rubber internal layer is extruded and, at the same time, pressurized air is filled in the interior of the rubber internal layer, fiber reinforcing layer is formed on the outer periphery of the rubber internal layer. Uncured rubber is extruded on the outer periphery of the reinforcing layer. Thermoplastic resin covers the outer periphery of the rubber external layer. Tubular body 11 in continuous form, the outer periphery of the resultant rubber external layer of which is covered by the thermoplastic resin layer and which has no mandrel therein, is cut off successively in pieces from end after being subjected to bending operation or cut off successively in pieces before being subjected to bending operation. Bent cut pieces obtained as mentioned above are installed in a form so as to be vulcanized and, after being removed from the form, frozen in order to separate the resin layer. The pressurized air encapsulated in the rubber internal layer is kept on being encapsulated until the covering of the outer periphery of the rubber external layer with the resin layer comes to an end. As the resin applied to the outer periphery of the rubber external layer, thermoplastic resin, which does not flow at vulcanizing temperature, such as 4-methylpentene-1 resin or the like is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing bent hoses for use in automobile hot water piping, fuel piping, and other machines.

[Conventional technology]

For rubber hoses without a reinforcing layer, bent hoses can be manufactured by injection molding using a mold.

However, this method does not have good manufacturing efficiency because each hose is manufactured one by one. Also, hoses with reinforcing layers cannot be manufactured using this method.

For this reason, hoses made only of rubber without a reinforcing layer or hoses with a reinforcing layer are continuously formed using an extruder or a reinforcing layer braiding machine, and then cut to the required length and bent. The hoses are inserted one by one around the outer circumference of the mandrel, placed in a vulcanizing can, and cured, and then removed from the mandrel after curing to produce a bent hose.

This method requires the application of a mold release agent to make it easier to insert the hose around the bent mandrel, and it is difficult to automate the insertion and removal of the rubber hose into and out of the mandrel, so this is done manually, which requires physical strength. However, there are problems such as the need to clean the mold release agent adhering to the hose.

[Lines to be solved by the invention]

The present invention provides a method for manufacturing curved hoses without the use of problematic curved mandrels to form the hose into a curved shape.

[Means for solving lines]

The means according to the present invention includes an inner rubber layer forming step of supplying pressurized air to the inside of the inner rubber layer while extruding an unvulcanized inner rubber layer from an extruder, and pressurizing the inside through the inner rubber layer forming step. A reinforcing layer forming step in which a fiber reinforced layer is formed around the outer periphery of the inner rubber layer in a state filled with air, and an outer rubber layer is formed by extruding unvulcanized rubber around the outer periphery of the reinforcing layer formed in the reinforcing layer forming step. After passing through the outer rubber layer forming step and the resin coating step of coating the outer periphery of the outer rubber layer formed in the outer rubber layer forming step with a thermoplastic resin layer, the resin obtained in the above step is coated. A bending process in which a long tubular body without a mandrel is bent from the end and the bent parts are sequentially cut, or the bent pieces obtained in the bending process are placed in a formwork. A process of holding the formwork for mounting, a vulcanization process of vulcanizing the bent cut piece installed in the formwork, a demolding process of taking out the bent piece after the vulcanization process from the formwork, and freezing of the demolded bent piece. and a peeling step of peeling off a resin layer from a frozen bent piece.

When forming the inner rubber layer, in order to seal pressurized air inside, pressurized air is supplied from the head of the extruder for the inner rubber layer, and at the end of the inner rubber layer coming out of the extruder. Close it by applying a stopper or crimping it flat. The pressurized air sealed in the inner rubber layer is kept sealed until the outer periphery of the outer rubber layer is coated with the resin layer. For example, 200m
If manufacturing is to be completed at the desired length, pressurized air is filled in until the end is plugged and the resin layer is coated around the outer rubber layer, and then cut to the specified length and bent. Perform processing. In addition, if the resin layer is coated and then sequentially cut to a predetermined length from the end, the inner and outer rubber layers and the resin layer are flattened together and cut immediately before the crushed area, and the cut portion is Make sure that the air in the rear part does not leak and maintain the pressurized air condition.

In the present invention, the resin applied to the outer periphery of the outer rubber layer is a thermoplastic resin that does not flow at the vulcanization temperature. Examples of this resin include 4-methylpentene-1 resin.

[Effect]

In the present invention, the reinforcing layer, the outer rubber layer, and the resin layer are formed with pressurized air sealed in the inner rubber layer, so when forming the reinforcing layer, the outer rubber layer, and coating the resin layer, The inner diameter can be prevented from changing. Since the resin layer is formed on the outer periphery of the outer rubber layer, when the unvulcanized inner and outer rubber layers are bent, the cross section of the bent portion can be maintained in a substantially perfect circular shape around the entire circumference. When bending the resin layer, it is difficult to bend it in a hardened state, so it is done in a softened state so that it can be bent. After putting it in a mold and vulcanizing it to keep it bent, and then removing it from the mold, the outer resin layer is cooled, frozen, and peeled off, making it easy to remove the resin layer.
Since the resin layer is a thermoplastic resin, it can be melted and reused.

(Example) The figure shows a process diagram of an example of the present invention. An inner rubber layer with an inner diameter of 9 mm and an outer diameter of !2 mm was continuously extruded and molded while enclosing air at a pressure of 5 kg/crlI'' inside the inner rubber layer extruded from the mold.

In this inner rubber layer forming step, an adhesive was applied to the outer periphery of the continuously formed inner rubber layer, and the reinforcing layer was then continuously introduced into a reinforcing layer braiding machine to form a reinforcing layer around the outer periphery of the inner rubber layer. The tubular body produced from this reinforcing layer forming step was continuously put into an extruder, and an unvulcanized outer rubber layer of EPDM was formed around the outer periphery of the reinforcing layer to have an outer diameter of 19 cm. Following this step of forming the outer rubber layer, it is placed in a resin extruder and sealed around the outer rubber layer under vacuum using 4-methylpentene-1 resin (heat distortion temperature 200%).
A resin coating step was carried out in which a resin layer having a thickness of 2IIIB and having a melting point of 247σ) was continuously coated. At this time, two V-shaped grooves were formed diametrically symmetrically along the longitudinal direction on the outer surface of the resin layer to make the resin more likely to break in the resin layer peeling step to be performed later.

The temperature of the resin layer at both ends coming out of this resin extruder was set to about 150℃.
After cooling to about C" and making it flexible, put one end into a bender and bend it into an L shape. Immediately after the bent part, press it flat with a crimping machine and glue the inner surface with its own viscosity. The L-shaped bent portion was separated from the elongated body while preventing pressurized air from leaking from inside the elongated body at the rear.

After a tubular elongated body with a total length of 200 m coated with a resin layer in the resin coating step is once cooled and cut into a predetermined length, the resin layer may be heated to 150 C to impart plasticity and then bent.

After going through a formwork holding process in which the bent pieces obtained in this bending and cutting process are put into a two-part formwork, 1. Put it in the vulcanizer 1
Vulcanization was performed at 65σ for 30 minutes.

During this vulcanization, if one end is crimped and closed as described above, pressurized air of about 1 k\cm2 may be introduced from the other end to seal the other end and vulcanize.

After the vulcanization process, the bent pieces are taken out of the mold.The bent pieces taken out from the mold are placed in a cooling tank, cooled with water, and then cooled with liquid nitrogen to -20°C to make them embrittle. A product was obtained through a peeling process in which the outer resin layer was crushed and removed using a crusher such as a roller.

When the bent portion of this product was cut and the deviation of the cross section was examined, it was found that the outside of the curve was slightly thinner than the inside.

〔Effect of the invention〕

According to the method for manufacturing a curved hose of the present invention, a curved hose can be efficiently manufactured without using a labor-intensive and time-consuming curved mandrel.

[Brief explanation of drawings]

The drawings are process diagrams of one embodiment of the manufacturing method of the present invention. Inner comb eyebrow formation process Reinforcement layer formation process ↓ Same as Tadashi Yamamoto; O4・″...> ◆ Bending cutting process ↓ Mold holding process ↓ Karo Ishiko Kogyo J Presentation ↓ Demolding process ↓ 51] East process ↓ S! Two release process hand Continued Supplementary Positive book (spontaneous)

Claims (1)

[Claims] (1) An inner rubber layer forming step in which pressurized air is supplied to the inside of the inner rubber layer while extruding the unvulcanized inner rubber layer from an extruder; A reinforcing layer forming step in which a fiber reinforcing layer is formed around the outer periphery of the inner rubber layer in a state filled with compressed air, and an outer rubber layer is formed by extruding unvulcanized rubber around the outer periphery of the reinforcing layer formed in the reinforcing layer forming step. After going through an outer rubber layer forming step to form a rubber layer, and a resin coating step to cover the outer periphery of the outer rubber layer formed in the outer rubber layer forming step with a thermoplastic resin layer, the resin obtained in the above step is coated. A bending process in which a long tubular body without a mandrel is bent from the end and the bent parts are sequentially cut, or the bent pieces obtained in the bending process are placed in a formwork. A vulcanization process that vulcanizes the bent cut pieces installed in the formwork, a demolding process that takes out the bent cut pieces that have undergone the vulcanization process from the formwork, and a mold removal process that removes the bent cut pieces that have been removed from the mold. A method for manufacturing a bent hose, comprising a freezing step and a peeling step of peeling a resin layer from a frozen bent piece.