JPH088100Y2 - Core metal for pipe forming - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core metal for molding various synthetic resin and rubber tubes.

[0002]

2. Description of the Related Art For example, as a method for manufacturing a flexible tube made of a thermoplastic synthetic resin by using a core metal, Japanese Patent Publication No. 34-10.
780, Japanese Patent Publication No. 36-15379, Japanese Patent Publication No. 39-397
There are 4 etc. In these methods, an inner layer of a flexible tube is formed on a cored bar, a reinforcing core is spirally wound on the cored layer, an outer layer is further formed, the inner layer resin and the outer layer resin are heat-bonded, and after cooling, This is a method of removing the core metal.

[0003]

However, in these methods, the core metal is an integral body, and even if it is desired to change the pipe diameter partially, the whole core metal must be changed, and the synthetic resin and the core metal are required. It is very difficult to pull out this if the core metal is long because it will be in close contact. The present invention provides a core metal for forming a pipe, in which the diameter of the pipe and the like can be easily changed and the core metal can be easily removed.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a core metal for tube forming in which at least two single bodies each having a screw joint structure at a longitudinal end thereof are connected and integrated by the screw joint fitting structure. Has succeeded in solving the above problems.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view including a partial cross-section showing an example of a cored bar of the present invention.
The ends have screw joint fitting portions 3 and 3 ', which are connected and integrated. The one shown in FIG. 1 has a diameter larger than that of the middle portion only for the single end of the core bar, but the one shown in FIG. 2 has a long core 1 for the single cores 2, 2'having the same diameter. It is divided. It is preferable that the individual units have a fitting structure in which the axes of the individual units are aligned with each other to prevent distortion as a core metal, and that the individual units are screwed together so that no gap is formed between the individual units.

FIG. 3 is a front view including a partial cross-section showing a specific example of molding a pipe using the cored bar of the present invention. A sheet-shaped synthetic resin inner layer 4 is formed on the outer peripheral surface of the cored bar 1. A hard reinforcing member 5 made of metal or the like and a synthetic resin outer sheath 6 are sequentially wound and heated to form a flexible tube 7, and one end of the cored bar 1 is fixed to a fixing jig 8, and the flexible tube 7 is cored. It is the one that is extracted from gold 1. There are also a method of forming the synthetic resin layer on the core metal by a coating method, a method of covering the core metal with a resin tube, and the like.

In this case, as a method of extracting the tube, a method of holding the single body 2'at the end of the core metal 1 together with one end of the flexible tube 7 with a claw (not shown) and rotating the tube 7 together with the single body 2 '. There is. At this time, the screw joint fitting portions 3 and 3'determine the thread cutting direction in a direction in which the spiral reinforcement 5 of the flexible tube 7 is loosened, and the pitch of the screw is set smaller than the spiral pitch of the flexible tube. As a result, the flexible tube 7 comes out from the core metal 1 (single body 2) while being twisted in the direction in which the reinforcing body 5 of the flexible tube expands in diameter as the end piece single body 2'of the core metal rotates. .

As another method of extracting the tube, only the single body 2'of the end of the cored bar 1 is extracted first, and then the end of the flexible tube is grasped by a claw (not shown) and then extracted as it is. Alternatively, it is a method in which the spiral reinforcing member 3 is pulled out while twisting in a loosening direction. In this case, even if the end of the flexible tube and the end 2'of the cored bar are in close contact, the contact area is small,
The end 2 of the core bar can be easily removed.

It should be noted that, at the time of extracting these, if compressed air, which is usually used, is introduced between the inner surface of the flexible tube and the core metal, it can be more easily extracted.

Further, it is also effective to interpose a resin layer having a releasability such as a fluororesin between the surface of the cored bar and the flexible tube 7 because the cored bar can be extracted very easily. In this case, only the core metal may be extracted first, and then the fluorocarbon resin layer may be peeled off from the flexible tube, or the core metal may be extracted together with the fluorocarbon resin layer.

[0011]

EXAMPLE As shown in FIG. 1, a core metal 1 in which a single body 2 having a diameter of 50.8 mm is screwed to one end of a single body 2 having a diameter of 50.8 mm, and an outer surface having a thickness of 0.5 mm is used. Wrap a thermoplastic polyurethane sheet, wrap a glass cloth on it, wrap a 0.2 mm thick thermoplastic polyurethane sheet, and wrap a 1.4 mm thick steel wire spirally at a 10 mm pitch. , And on top of that 0.5m thick
After wrapping the thermoplastic polyurethane sheet of m in the heating device at 205 ° C for 20 minutes, take it out and cool it, fix one end of the cored bar to the fixing jig, and screw the mandrel The flexible tube was grasped with a claw, the screw was loosened, and the flexible tube was pulled out from the mandrel. In addition,
The core metal used was one coated with a fluororesin having a thickness of 0.1 mm.

Example 2 In the same manner as in Example 1, using a simple substance 2 having a diameter of 50.8 mm over the entire length and a core metal 1 shown in FIG. Using vinyl resin, wind a 0.2 mm thick film made of fluororesin on the surface of the core metal, heat it for 20 minutes in a heating device at 180 ° C, take it out and cool it, and only screw the core metal Then, one end of the flexible tube was grasped with a claw and pulled out from the cored bar.

[0013]

EFFECTS OF THE INVENTION According to the present invention, it is possible to easily manufacture a flexible tube whose diameter and the like are changed according to the dimensions of the fitting without changing the whole core metal by combining the single units, and the manufacturing cost is also increased. It will be cheaper. Further, by separating the core metal, the core metal can be easily pulled out from the molded pipe, and the productivity is improved.

[Brief description of drawings]

FIG. 1 is a front view including a partial cross section showing an example of the present invention.

FIG. 2 is a front view including a partial cross-section showing another example of the present invention.

FIG. 3 is a structural cross-sectional view showing a specific example when a pipe is molded using the cored bar of the present invention.

[Explanation of symbols]

 1: core metal 2, 2 ': simple substance 3, 3': screw joint fitting portion 4, 6: synthetic resin layer 5: reinforcing core 7: flexible tube 8: fixing jig

Claims (2)

[Scope of utility model registration request] 1. A core metal for pipe forming in which at least two single bodies each having a threaded joint fitting structure at a longitudinal end thereof are connected and integrated by the threaded joint structure. 2. A core metal for pipe forming, in which individual bodies having different diameters or cross-sectional shapes are connected and integrated.