JP2876910B2 - Corrugated tube molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a corrugated tube without using a mold, and in particular, to prevent the deterioration of molding accuracy and the occurrence of molding defects due to the adhesion of a cooling liquid to a metal tube. The present invention relates to a corrugated tube molding method.

[0002]

2. Description of the Related Art As an example of a method for manufacturing a corrugated tube, there is conventionally known a hydraulic bulging process and Japanese Utility Model Application Laid-Open No. 63-85319, which does not use a mold. The processing apparatus disclosed in this publication supports both ends of a metal pipe, locally applies heat to the metal pipe, applies a load from the axial direction, cools the steel pipe immediately after that, finishes forming one crest, and repeats this process sequentially and repeatedly. Is formed.

Also, a long corrugated tube forming apparatus is known which can form a corrugated tube with high accuracy and with almost no increase in the size and complexity of the apparatus, even in the case of a long metal tube. JP-A-4-91824).

[0004] In the molding of the corrugated tube according to the above-mentioned publication, cooling water is used as a refrigerant for cooling the bulging portion formed by heating and compression.
Immediately after compression, cooling water is injected toward the bulging portion.

[0005]

However, in the molding of the corrugated tube according to the above publication, if the molding cycle time is shortened in order to increase the productivity, the molding accuracy of the corrugated tube 21 is reduced as shown in FIGS. Deterioration and molding failure occur. FIG. 3 shows a case where the diameter of the bulging portion 21a of the corrugated tube 21 varies, and FIG. 4 shows a case where the corrugated tube 21 is curved in the direction of arrow A.

Although the details of the cause of such a molding failure are not clear, if the molding cycle time is shortened, the cooling water used in the previous molding of the bulging portion may remain on the surface of the metal tube. It is considered that since the heating for forming the next bulging portion is performed, the variation in the adhesion of the cooling water directly appears as the non-uniformity of the next heating temperature. Therefore, a portion that is easily deformed and a portion that is hardly deformed are generated in the heating portion of the metal tube, and as a result, the molding accuracy in the circumferential direction and the axial direction of the metal tube is deteriorated and molding failure is caused.

[0007] In order to eliminate the variation in the adhesion of cooling water,
It is sufficient to perform cooling with a gas such as compressed air instead of the cooling water. However, in this case, there is a problem that the cooling capacity is extremely reduced and the molding cycle time is prolonged.

An object of the present invention is to provide a corrugated tube molding method capable of shortening the molding cycle time without causing deterioration in molding accuracy or occurrence of molding defects, focusing on the above problems.

[0009]

According to the present invention, there is provided a method of forming a corrugated tube, comprising: holding a metal tube by a chuck portion; heating the metal tube locally; By compressing the metal tube in the axial direction, the heating portion is bulged radially outward, and then the cooling liquid is sprayed on the bulging portion to cool the bulging portion. It consists of a method of blowing gas toward the metal tube.

[0010]

In the corrugated tube forming method thus constituted, when a bulging portion bulging outward in the radial direction is formed in the metal tube, a cooling liquid is sprayed toward the bulging portion. When the bulging portion is cooled by the cooling liquid, gas is blown toward the portion where the cooling liquid has adhered. for that reason,
The coolant adhering to the metal pipe is blown off by the gas, and the coolant is almost completely removed.

Therefore, the heating temperature at the time of forming the next swollen portion does not become non-uniform, and the heated portion of the metal tube does not have easily deformable portions and hardly deformable portions. As a result, the heating section is uniformly deformed, and deterioration of molding accuracy and occurrence of molding failure are prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the method for forming a corrugated tube according to the present invention will be described below with reference to the drawings.
First, a forming apparatus for carrying out the present invention will be described.

In FIG. 1, reference numeral 1 denotes a gantry on which servo motors 5a and 5b and ball screws 7a and 7b are supported. The servo motors 5a, 5b and the ball screws 7a, 7b are connected via gear mechanisms 6a, 6b, respectively. The ball screws 7a and 7b respectively support hydraulic chucks 2a and 2b (which may be chucks such as an air chuck and an electromagnetic chuck).

Here, the hydraulic chuck 2b constitutes a first chuck portion for chucking the metal tube 9 from the outer periphery at a middle portion in the longitudinal direction, and the hydraulic chuck 2a chucks the metal tube 9 from the outer periphery at a middle portion in the longitudinal direction. 2 constitute the chuck portion. The ball screw 7b, the gear mechanism 6b, and the servo motor 5b constitute driving means for driving the first chuck section in the axial direction of the metal tube. The ball screw 7a, the gear mechanism 6a, and the servo motor 5a are connected to the second chuck section. Is configured in the axial direction of the metal tube.

A high frequency coil 3 is provided between the two chuck portions.
Heating and cooling means provided with a cooling liquid injection pipe 8. The high-frequency coil 3 surrounds the metal tube 9 in the circumferential direction, and heats the metal tube 9 locally in the axial direction. Immediately after heating, the cooling liquid injection pipe 8 is configured to inject cooling water as a cooling liquid to a local heating unit to cool the local heating unit.

Reference numerals 4a and 4b denote bases for a metal tube and a corrugated tube, respectively. The receiving tables 4a and 4b, the hydraulic chucks 2a and 2b, and the high-frequency coil 3
Are arranged with their axes aligned in the feed direction.

Next to the heating and cooling means provided with the high-frequency coil 3 and the cooling liquid injection pipe 8, a metal pipe 9 with cooling water adhered thereto is provided.
An annular gas injection pipe 11 for blowing compressed air toward the portion is disposed. The gas injection tube 11 is a metal tube 9
It has a plurality of oblique injection holes 11a opening toward the bulging portion 9a. The gas injection pipe 11 is connected to an air compressor 13 via a passage 12. An electromagnetic valve 14 is arranged in the middle of the passage 12. The electromagnetic valve 14 is opened and closed by a signal from a control unit (not shown), and compressed air from the air compressor 13 is injected from the gas injection pipe 11 toward the entire peripheral surface of the metal pipe 9 only when the electromagnetic valve 14 is opened. It has become.

Next, a method of manufacturing a corrugated tube using the above apparatus and its operation will be described. First, the long metal tube 9 is inserted from the receiving table 4a into the hydraulic chuck 2a and the high-frequency coil 3, and the front end side of the metal tube 9 in the insertion direction is chucked by the hydraulic chuck 2b. Next, the middle part of the metal pipe 9 is chucked by the hydraulic chuck 2a. Subsequently, a high-frequency current is applied to the high-frequency coil 3 to heat the metal tube 9 to a predetermined temperature locally in the axial direction and over the entire circumference in the circumferential direction.

As soon as the heating section is heated to a predetermined temperature, the servo motor 5a operates and the ball screw 7 is connected via the gear 6a.
a is actuated, the hydraulic chuck 2a moves in the axial direction for a predetermined distance to apply a load to the metal tube 9, and locally expands and deforms the heating unit. Immediately thereafter, the bulging portion 9a is cooled by the cooling water injected from the cooling liquid injection pipe 8, and a single crest is formed.

When the swelling portion 9a is cooled by the cooling water, the solenoid valve 14 is opened, and the oblique injection hole 11 of the gas injection pipe 11 is opened.
a, compressed air is injected toward the bulging portion 9 a of the metal tube 9. Thereby, the cooling water adhering to the metal pipe 9 is blown off, and the cooling water is almost completely removed from the surface of the metal pipe 9.

Next, after releasing the hydraulic chuck 2a,
The servo motor 5b is operated, the ball screw 7b is moved via the gear 6b, the hydraulic chuck 2b is moved by one pitch in the metal pipe feed direction, and the metal pipe 9 is advanced by one pitch in the metal pipe feed direction. . The hydraulic chuck 2a is simultaneously returned to the original position.

When the metal tube 9 is fed by one pitch, the metal tube 9 is chucked by the hydraulic chuck 2a. Subsequently, the hydraulic chuck 2b is released, the servomotor 5b is operated, and the ball screw 7b and the hydraulic chuck 2b are moved by one pitch in the direction opposite to the metal pipe feed direction via the gear 6b. The chuck 2b chucks the corrugated portion (the portion formed on the corrugated tube in the middle of the long metal tube 9).

When the positioning of the metal tube 9 in the feed direction is completed, the portion to be formed next to the metal tube 9 is heated by the high-frequency coil 3. Here, since the cooling water adhering to the surface of the metal tube 9 has been sufficiently removed by the injection of the compressed air at the time of forming the bulging portion 9a, the temperature variation of the heating section due to the adhesion of the cooling water is reduced. Will be resolved. Therefore,
The heating unit is uniformly heated, so that the deterioration of molding accuracy and the occurrence of molding defects during molding of the bulging portion due to the compressive force are eliminated.

By repeating such a process, the bulging portion is formed one by one, and the cycle of feeding the metal pipe 9 one by one after forming is repeated by the required number of peaks to form the corrugated tube.

In this embodiment, cooling water is used as the cooling liquid. However, the present invention is not limited to this. For example, a structure using a water-soluble quenching liquid or the like may be used. Although compressed air is used as the gas, a configuration using nitrogen, carbon dioxide, or the like may be used. Alternatively, a configuration may be used in which cooling of the bulging portion and removal of the cooling liquid are performed simultaneously using a low-temperature gas.

[0026]

According to the present invention, the following effects can be obtained.

(1) The metal tube is held by the chuck portion,
After the metal tube is locally heated, the chuck is moved to compress the metal tube in the axial direction to expand the heating portion radially outward, and then inject the cooling liquid into the expanded portion to expand it. Since the part is cooled and then the gas is blown toward the part of the metal pipe to which the cooling liquid has adhered, the temperature of the heating part does not vary, and the entire heating part can be uniformly heated.

(2) Therefore, the heating portion can be formed uniformly by the compressive force acting on the metal tube,
It is possible to improve molding accuracy and prevent molding defects.

(3) In order to prevent deterioration of molding accuracy and molding defects by the conventional method, the next molding portion is heated after the cooling liquid is dried, but in the present invention, the gas is injected by gas injection. Since the cooling water adhering to the metal pipe is forcibly removed, the next bulging portion can be formed without waiting for the adhering cooling water to dry. Therefore, the molding cycle time of the bulging portion can be shortened, and the productivity of the corrugated tube can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view of a corrugated tube forming apparatus for carrying out the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a partially enlarged front view of a corrugated tube in which molding accuracy is reduced by a conventional molding method.

FIG. 4 is a partially enlarged front view of a corrugated tube in which molding failure has occurred by a conventional molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stand 2a, 2b Chuck part 3 High-frequency coil 4a, 4b Receiver 5a, 5b Servo motor 6a, 6b Gear mechanism 7a, 7b Ball screw 8 Coolant injection pipe 9 Metal pipe 11 Gas injection pipe

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-192425 (JP, A) JP-A-63-203217 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21D 15 / 06,19 / 08 B21C 37/00 C21D 9/08

Claims (1)

(57) [Claims] 1. A metal tube is held by a chuck portion, and after the metal tube is locally heated, the metal tube is axially compressed by movement of the chuck portion to expand the heating portion radially outward. Next, a cooling liquid is injected into the bulging portion to cool the bulging portion, and thereafter, a gas is blown toward a portion of the metal pipe to which the cooling liquid has adhered, thereby forming a corrugated tube.