JPH11319934A - Manufacture of and device for interior grooved tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform grooving with satisfactory productivity by giving vibrations in the axial direction so that frictional resistance between a working tool and tube stock is more effectively reduced when forming sharper and deep grooves on the inside surface of the tube stock. SOLUTION: In this manufacturing method, a floating plug 2 and a freely rotatable grooved plug are inserted into a metal tube stock 1, the tube stock 1 is continuouslry pulled out along the tube axial direction, while contracting the diameter of the tube stock 1 by the floating plug 2 and a floating die 20, and by plural working balls 30 pressing the tube stock 1 on the grooved plug 3 while revolving and idling at a high speed around the stock 1 in the position of the grooved plug, lots of grooves are worked on the inner peripheral surface of the tube stock 1. In this case, the floating die 20 is vibrated along the tube axial direction by a vibration mechanism 5.

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 an inner grooved tube used for a heat exchanger tube for a heat exchanger such as a refrigerator or an air conditioner, and an apparatus for manufacturing the same. The present invention relates to a method and an apparatus for manufacturing an inner grooved pipe suitable for processing a deeper groove in the inner surface of the pipe.

[0002]

2. Description of the Related Art Conventionally, for example, in order to process a seamless small-diameter inner grooved pipe having a number of spiral grooves on the inner surface,
For example, a manufacturing method described in JP-A-55-103215 is employed. The manufacturing method described in the publication is a rolling process, in which a floating plug and a grooved plug rotatably connected via a rod to the floating plug are inserted into a metal pipe, While continuously pulling out the raw pipe along the pipe axial direction in a state where the grooved plug is located downstream of the floating plug, while reducing the diameter of the raw pipe by the floating plug and the floating die,
At a position of the grooved plug, a plurality of processing balls for revolving around the raw tube while revolving at a high speed and pressing the raw tube against the grooved plug form a pipe shaft on the inner peripheral surface of the raw tube. Are formed in parallel with each other with a predetermined twist angle.

In order to improve the heat transfer performance of the inner surface of this kind of tube with an inner surface groove, the inner surface groove is made deeper,
Sharpening the fin shape between adjacent grooves (making the fin apex angle smaller). When machining deeper and sharper grooves on the inner surface in this way, the frictional resistance between tools such as plugs, dies, balls, etc. and the raw tube at the part where rolling is performed becomes larger, and the tube is easily broken. Therefore, the processing speed must be greatly reduced, and the productivity becomes poor. As means for further reducing the frictional resistance between the tool and the pipe in such a roll-formed portion and preventing the pipe from breaking during groove processing and preventing a reduction in the processing speed, for example, JP-A-5-92207 discloses A plurality of processing balls for pressing the raw tube against the grooved plug at the position of the grooved plug are held by a rotary die, and a drive shaft having an insertion hole for passing the raw tube is attached to the rotary die, and a driving mechanism is used. It has been proposed to rotate a rotary die through the drive shaft and to vibrate the drive shaft in the axial direction (ultrasonic vibration) by a vibration mechanism. By vibrating the drive shaft along the axial direction in this way, the contact interface between the processing ball and the raw tube is relatively vibrated in a direction parallel to the interface in the portion of the rotary die, and the lubricating oil is applied to the interface. To effectively reduce the frictional resistance. At the same time, vibration is also transmitted to the raw pipe, so the frictional resistance between the grooved plug and the raw pipe and the frictional resistance between the floating die and the raw pipe are reduced, and the frictional resistance required for pulling out the raw pipe is comprehensively reduced. To be reduced.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 5-922 is disclosed.
The means proposed in JP-A-07-2007 can reduce the frictional resistance between the raw pipe and the processing tool, but has the following problems. The first is that, because each processing ball held by the rotary die is violated during processing by vibration, the rolling pattern due to the processing ball appearing on the surface of the product (inner grooved tube) is significantly disturbed, and the product has a surface defect. It is easy. Second, when the drive shaft is vibrated, the equipment becomes complicated and large, and the installation cost of the vibrating mechanism becomes extremely expensive.

[0005] An object of the present invention is to provide an axial vibration to a machined portion in a case where a sharp and deep groove is machined in the inner surface of a tube without pulling a processing ball during drawing of the tube. An object of the present invention is to provide a method of manufacturing an inner grooved tube which can be processed at a high speed and an apparatus therefor. It is another object of the present invention to provide a method and apparatus for manufacturing an inner grooved pipe that can vibrate a processed portion in an axial direction during drawing of a raw pipe with simpler and smaller equipment.

[0006]

According to a first aspect of the present invention, there is provided a method for manufacturing an inner grooved tube, comprising the steps of: providing a floating plug and a floating plug in a metal pipe; The grooved plug 3 rotatably connected via the rod 31 is inserted, and the raw tube 1 is moved along the pipe axis direction in a state where the grooved plug 3 is located downstream of the floating plug 2. The tube is continuously pulled out, and while the diameter of the tube 1 is reduced by the floating plug 2 and the floating die 20, the tube 1 rotates around the tube 1 at the position of the grooved plug 3 while revolving at high speed. In the process of forming a large number of grooves on the inner peripheral surface of the raw tube 1 by a plurality of processing balls 30 pressing the raw tube 1 against the grooved plug 3, the floating die 20 is connected to the tube axis of the raw tube 1. direction It is characterized by vibrating along.

According to a second aspect of the present invention, a floating plug 2 and a floating die 20 are provided on the upstream side of the metal tube 1 in the drawing direction in order to solve the above-mentioned problem. A grooved plug 3 rotatably connected to the floating plug 2 via a rod 31 on the downstream side in the drawing direction of the raw tube 1 and a rotation that rotates at a high speed around the grooved plug 3 Dice 3
2 and a plurality of processing balls 30 are held in the rotating die 32 so as to freely rotate while being pressed toward the outer peripheral surface side of the grooved plug 3. A vibrating mechanism 5 for vibrating the die 20 along the tube axis direction of the raw tube 1 is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method and an apparatus for manufacturing an internally grooved pipe according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing one embodiment of the apparatus for manufacturing an inner grooved pipe according to the present invention. On the upstream side in the drawing direction of the raw tube 1 made of a metal having good heat conductivity such as copper or copper alloy, aluminum or its alloy,
A floating plug 2 inserted into the shell 1;
A floating die 20, which is located on the outer periphery of the raw tube 1 and is reduced in diameter and holds the floating plug 2 at a predetermined position, is provided. The raw tube 1 into which the floating plug 2 has been inserted is pulled out rightward in FIG. 1 by pulling means (not shown). A vibration mechanism 5 for ultrasonically vibrating the floating die 20 along the axial direction is installed on the floating die 20 at an upstream side in the drawing direction of the raw tube 1.
Is applied to the floating die 20 via a horn (amplitude amplification mechanism) 50.

A plurality of parallel grooves (protrusions) 3a having a predetermined twist angle with respect to the axial center are formed on the outer peripheral surface on the downstream side of the floating plug 2 in the drawing direction of the raw tube 1. The attached plug 3 is rotatably connected via a rod 31, and the grooved plug 3 is also inserted into the raw tube 1. A hollow rotary die 32 is provided on the outer peripheral portion of the grooved plug 3 so that the grooved plug 3 is located at the center, and the rotary die 32 is moved by a driving device (not shown). 3 is rotated at high speed. Inside the rotary die 32, a flared inner peripheral surface 32 diverging toward the downstream side in the drawing direction.
a is formed, and a plurality of densely arranged processing balls 30 are inscribed in the inner peripheral surface 32a so as to idle.

Each of the processing balls 30 is held in the rotary die 32 while being pushed into the inside by a stopper 34 held through a bearing 33 provided on the outlet side in the rotary die 32. The periphery of the grooved plug 3 is revolved by the rotation of the die 32, and the raw tube 1 is pressed from its outer periphery to the peripheral surface of the grooved plug 3. The bearing 33 and the stopper 34
Is pushed by a pushing amount adjusting member (not shown) that rotates together with the rotary die 32 so that the pushing amount to the upstream side in the pulling-out direction can be adjusted against the flared inner peripheral surface 32a. The adjustment is such that the pressing force of each processing ball 30 against the raw tube 1 is adjusted.

On the downstream side of the rotary die 32 in the drawing direction of the raw tube 1, a shaping die 4 for shaping the raw tube 1 while reducing its diameter by emptying is provided.

The inner grooved pipe is manufactured in the following manner using the apparatus for manufacturing an inner grooved pipe according to the above embodiment. The floating plug 2 and the grooved plug 3 are inserted into the raw tube 1 and the raw tube 1 is set in the state shown in FIG.
As a result, the floating die 20 is vibrated in the axial direction, and the rotary die 32 is rotated at a high speed (for example, 300 mm).
(00 rpm), the raw tube 1 is pulled in a pulling-out direction (rightward in the drawing) by a pulling means (not shown).
The tube 1 drawn as described above is reduced in diameter by the floating plug 2 and the floating die 20, and then the outer peripheral wall thereof is pressed toward the grooved plug 3 by the plurality of processing balls 30 rotating and revolving. You. At this time,
When the grooved plug 3 rotates, the grooved plug 3
The groove 3a on the front surface is transferred to the inner peripheral surface of the raw tube 1, and a number of spiral grooves 1a having a twist angle θ corresponding to the twist angle of the groove 3a in the grooved plug 3 are formed. Further, the inner grooved tube 1 'is manufactured by being evacuated when passing through the shaping die 4 and being shaped so that the cross-sectional shape becomes closer to a perfect circle while being reduced in diameter.

By vibrating the floating die 20 along the axial direction of the raw tube 1 during the manufacture of the above-mentioned inner grooved tube 1 ', the first stage in which the frictional resistance between the raw tube 1 and the working tool is the largest. In the reduced diameter portion, the lubrication of the interface between the base tube 1, the floating plug 2 and the floating die 20 is promoted, and the frictional resistance between the two is greatly reduced. When the floating die 20 is vibrated in this manner, the vibration is transmitted to the raw tube 1 at the same time.
And the frictional resistance between the grooved plug 3 and the processing ball 30 and the frictional resistance with the shaping die 4 are also reduced, so that the frictional resistance of the processing of the inner surface grooved tube 1 'can be reduced comprehensively. The vibration by the vibration mechanism 5 is applied to the portion of the floating die 20 where the frictional resistance between the workpiece 1 and the working tool is the largest in this type of rolling processing equipment, so that the effect of applying the vibration is reduced. In addition to the remarkable appearance, since there is almost no run-out of each of the processed balls 30, there is no possibility that a surface defect occurs in the product. Therefore, a groove having a deeper and sharper cross-sectional shape can be smoothly processed at a higher speed in the pipe.

(Example) A copper pipe having an outer diameter of 10 mm and a wall thickness of 0.4 mm, a grooved plug (FIGS. 2 and 3), an outer diameter R = 8 mm, a groove depth d = 0.25 mm, and a groove bottom. Angle (corresponding to the top angle of the convex part of the inner surface of the inner grooved tube) α = 20 °, twist angle θ '= 20 °, number of grooves = 50 processing balls Diameter = 10 mm, number = 4 Rotating die rotation speed = 30 Inner grooved tube product with a drawing speed changed in the range of 20 to 60 m / min. Outer diameter = 7 mm. Outer diameter = 7 mm. When,
A comparative example in which the floating die 20 was rolled without applying ultrasonic vibration was manufactured as an inner grooved tube. Each of these two types of inner surface grooved pipes was cut at several locations, and the depth of the grooves was measured to compare the state of the inner surface groove processing. FIG. 4 shows the results.

FIG. 4 shows the drawing speed on the horizontal axis and the processed groove depth on the vertical axis. In the case of the inner grooved pipe of the embodiment, the drawing speed is complete and satisfactory up to a drawing speed of 40 m / min. Internal groove processing could be performed. In addition, no surface defect occurred in the inner grooved pipe of each of these examples. On the other hand, the inner grooved pipe of the comparative example has a drawing speed of 20 m / mi.
only good internal groove processing could be performed up to n.
When the drawing speed exceeded 30 / min, the raw tube was broken.

[0016]

According to the method of manufacturing an inner grooved pipe according to the first aspect of the present invention, the floating die 20 is vibrated along the axial direction of the raw pipe 1 during processing of the inner surface of the pipe. The first with the largest frictional resistance between the pipe 1 and the machining tool
In the step diameter reduction portion, lubrication of the interface between the base tube 1 and the floating plug 2 and the floating die 20 is promoted, and the frictional resistance between the two is greatly reduced. When the floating die 20 is vibrated in this manner, the vibration is transmitted to the raw tube 1 at the same time.
In addition, since the frictional resistance with the processing ball 30 is also reduced, the frictional resistance of the processing of the inner grooved pipe 1 ′ can be reduced comprehensively. Further, in this type of rolling processing equipment, since the vibration is applied to the portion of the floating die 20 where the frictional resistance between the workpiece 1 and the processing tool is the largest, the effect of applying the vibration is more remarkable. In addition, since there is almost no run-out of each of the processed balls 30, there is no possibility of causing a surface defect on the product. Therefore, a groove having a deeper and sharper cross-sectional shape can be smoothly processed at a higher speed in the pipe.

According to the apparatus for manufacturing an inner grooved pipe according to the second aspect of the present invention, since the vibrating mechanism 5 is installed on the floating die 20, the structure of the equipment becomes simpler and smaller, and the equipment cost is reduced. It is cheaper and easy to add to existing equipment.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of an apparatus for manufacturing an inner grooved pipe according to the present invention.

FIG. 2 is a schematic front view of a grooved plug used in the embodiment.

FIG. 3 is a partial end view of the grooved plug of FIG. 2;

FIG. 4 is a diagram comparing the groove processing state of the inner surface by measuring the groove depth of each inner grooved tube of the example and each inner grooved tube of the comparative example.

[Explanation of symbols]

 θ, θ 'Helix angle α Apex angle d Groove depth R Outer diameter of grooved plug 1 Base tube 1a Groove 1' Inner grooved tube 2 Floating plug 20 Floating die 3 Groove plug 3a Groove 30 Work ball 31 Rod 32 Rotation Dies 32a Inner peripheral surface 33 Bearing 34 Stopper 4 Shaping die

Claims (2)

[Claims] 1. A floating plug 2 and a grooved plug 3 rotatably connected to the floating plug 2 via a rod 31 are inserted into a metal tube 1. With the grooved plug 3 located downstream of the floating plug 2, it is continuously pulled out along the pipe axis direction.
0, while reducing the diameter of the raw tube 1, at the position of the grooved plug 3, it revolves around the raw tube 1 at a high speed while rotating around and presses the raw tube 1 against the grooved plug 3. In the process of forming a large number of grooves in the inner peripheral surface of the raw tube 1 by using the plurality of processing balls 30, the floating die 20 is vibrated along the tube axis direction of the raw tube 1. Manufacturing method of inner grooved pipe. 2. A floating plug 2 and a floating die 2 are provided on the upstream side of the metal pipe 1 in the drawing direction.
0, a grooved plug 3 rotatably connected to the floating plug 2 via a rod 31 at a downstream side in the drawing direction of the raw tube 1, and a high speed around the grooved plug 3. A rotating die 32 is installed, and a plurality of processing balls 30 are slidably held in the rotary die 32 while being pressed against the outer peripheral surface of the grooved plug 3. A vibrating mechanism (5) for vibrating the floating die (20) along the tube axis direction of the raw tube (1).