JPH07164205A - Machining of pipe with inner surface spiral groove - Google Patents

Abstract

PURPOSE:To machine spiral grooves easily and exactly by cutting the spiral grooves inside the inner wall surface of a metallic pipe. CONSTITUTION:A metallic pipe 3 is made to pass through a die 2 mounted onto a puller to be drawn. A cutting tool 11 attached to the end of a thin rod 6 is inserted to a pulling position from the rear end of the metallic pipe. The cutting tool 11 is rotated to fit the pulling position of the die 2 to the cutting edge tip of the cutting tool 11, thus forming a spiral groove 13 in the inner wall surface of the metallic pipe 3.

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 an inner surface spiral grooved tube used as a heat transfer tube, and more particularly, to easily and accurately form a spiral groove on the inner wall surface of a metal tube by cutting. The present invention relates to a method of manufacturing a pipe having a spiral groove on the inner surface.

[0002]

2. Description of the Related Art The following three methods are well known as methods for forming a spiral groove for promoting heat transfer on the inner wall surface of a metal tube. Firstly, a cylindrical grooved sleeve is inserted into the metal pipe, and the metal pipe is relatively moved in the axial direction while the inner wall surface of the pipe is pushed into the groove of the sleeve by shrinking the pipe by some means from outside the pipe. There is a way. Secondly, there is a method of forming a predetermined groove by rolling on one surface of a metal strip, and then forming a pipe with the grooved surface inside and welding the joint. Thirdly, there is a method in which a cutting tool is inserted into the metal tube and the tool and the metal tube are subjected to rotation and axial feed to process the inner wall surface.

The above-mentioned first and second methods have already been put to practical use in mass production of copper pipes with internal grooves which are currently used as heat transfer pipes for heat exchangers for air conditioners. However, the spiral angle of the inner surface groove formed by the first method with respect to the axis is about 0 to 30 degrees, and the depth of the groove is about 0.2 mm, which is relatively shallow. In the second method, the spiral angle can be set arbitrarily from 0 to 90 degrees,
The depth of the groove is similar to that of the first method.

However, in the metal tube with the inner surface groove, the spiral angle is close to 90 degrees (the groove is formed in a direction substantially orthogonal to the axis of the metal tube), and the groove depth is the first. It is known that a groove deeper than the groove formed by the second method exhibits various excellent characteristics as a heat transfer tube. Therefore, in order to manufacture an inner grooved pipe satisfying the above conditions, the third method as disclosed in Japanese Patent Publication No. S57-40437 has been proposed.

[0005]

However, in the case where the cutting tool is inserted into the metal pipe and the inner wall surface of the metal pipe is to be cut (machining without cutting chips by raising the plow) according to the third method, There are the following problems, and there is no known example in which the third method is carried out on an industrially applicable scale.

First, since the rotational diameter of the cutting bit cutting edge must be larger than the minimum inner diameter of the pipe to be processed, there is a problem that the machining procedure such as attachment and detachment of the bit becomes complicated and the machining efficiency becomes extremely low. is there.

Secondly, when a groove is formed on the inner wall surface of a thin metal tube by using a cutting tool, the wall surface has a small rigidity, so that the wall surface is easily deformed and cannot be cut or the depth of cut varies. There is a problem.

Thirdly, when it is desired to stably process a thin and thin metal tube, it is extremely important to suppress the runout of the cutting tool, but the rigidity of the thin rod that holds the cutting tool is small. There is a problem that it is difficult to perform stable processing.

Therefore, an object of the present invention is to provide a method of processing an inner surface spiral grooved pipe which can easily and accurately process a spiral groove on an inner wall surface of a metal pipe by cutting.

[0010]

In the present invention, in order to solve the above problems, firstly, a metal tube is drawn out through a die, and a cutting tool attached to the tip of a thin rod is drawn out from the rear end of the metal tube. Inserted to the position, rotate the cutting tool, and align the drawing position of the die with the cutting edge of the cutting tool to form a spiral groove on the inner wall surface of the metal tube. The processing method of is provided.

In order to match the drawing position of the die with the cutting edge of the cutting tool, the drawing position of the die is moved to the cutting edge of the cutting tool. Further, it is desirable that a cylindrical sleeve having an outer diameter substantially equal to the inner diameter of the metal pipe pulled out by a die is attached near the tip of the thin rod.

In the present invention, secondly, n dies that can move in the axial direction are arranged on the same axis at a predetermined interval, and the metal tube is pulled out through the n dies. N-1 cylindrical sleeves having an outer diameter substantially equal to the inner diameter of the metal pipe pulled out by one die are attached to the thin rod in a freely rotatable state so as not to move in the axial direction, And, a processing means having a cutting tool slightly smaller than the diameter of the (n-1) th cylindrical sleeve from the previous stage is attached to the tip of the thin rod from the rear end of the pipe, and n-
Match the positions of one die and n-1 cylindrical sleeves respectively, and perform drawing processing on the metal pipe to reduce the outer diameter and wall thickness, and the drawing position and cutting tool of the nth die from the previous stage. A method for processing an inner surface spiral grooved tube, characterized in that a spiral groove is formed on the inner wall surface of the metal tube by allowing the metal tube to continue withdrawing while matching the blade edge thereof.

As the die, a rotary die composed of a plurality of planet-shaped balls or rolls may be used.

By changing the positional relationship between the drawing position of the metal tube and the cutting tool in the die, the spiral groove processed portion and the unprocessed portion can be formed at predetermined positions on the inner wall surface of the metal tube. . Similarly, the cutting depth of the cutting tool into the inner wall surface of the metal tube can be adjusted by changing the positional relationship between the drawing position of the metal tube in the die and the cutting tool.

[0015]

In the first aspect of the invention, since the spiral groove cutting process is performed on the inner wall surface of the metal pipe while restraining the outer surface of the metal pipe with the die, the reaction force associated with the cutting may deform the wall surface of the metal pipe. Absent. Further, since the cylindrical sleeve is provided on the thin rod, it is possible to suppress core deviation around the rotation axis of the cutting tool, and it is possible to accurately form the spiral groove. Further, by adjusting the contact pressure between the blade of the cutting tool and the inner wall surface of the metal tube, it is possible to easily adjust the depth of the groove and easily form the portion with and without the groove.

Further, in the second invention, in addition to the operation according to the first invention, since n dies are used, the outer diameter dimension can be accurately processed in one step, and redrawing is unnecessary. . Further, since the metal tube is sandwiched between the outer side and the inner side by the n-1 dies and the cylindrical sleeve, the wall thickness of the metal tube can be adjusted.

[0017]

First Embodiment A first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an overall view of an inner surface spiral grooved tube manufacturing apparatus of this embodiment. This device includes a drawing device 5 such as a draw vent having a die 2 held by a die holder 1 that can move in the axial direction, and a carriage 4 for drawing the metal pipe 3, and a cutting tool inserted into the metal pipe 3. A thin rod 6 (not shown),
It is composed of a rotary head 7 for rotating the thin rod 6 while holding it at a fixed position, and a drive device 8 for driving the rotary head 7. The thin rod 6 is in the shape of a hollow pipe, and the emulsion for both cooling and lubrication can be supplied to the spiral groove cutting portion in the pipe from the rear end through the rotary joint 9.

FIG. 2 is an enlarged sectional view of the portion A in FIG. 1 showing the first embodiment of the present invention.
2A shows a state in which the spiral groove is not processed, and FIG. 2B shows a state in which the spiral groove is being processed. As shown in FIG.
The thin rod 6 includes a cutting tool 11 having a blade at its tip and a hollow cylindrical sleeve 1 having an outer diameter substantially equal to the inner diameter of the metal tube 3.
0 is rotatably attached so as not to move in the axial direction. It should be noted that the cutting tool 11 is manufactured so that the turning diameter of the cutting edge is larger than the inner diameter of the metal tube 3 after passing through the die 2.

Next, the spiral groove machining method of this embodiment will be described. First, the thin rod 6 is inserted into the metal tube 3, and the cutting tool 11 is rotated at a predetermined speed, and the metal tube 3 is pulled out through the die 2 at a predetermined speed in the direction of the arrow in the drawing. At this time, by moving the die 2 in a direction opposite to the moving direction of the metal tube 3 and aligning the bearing portion 12 of the die 2 and the axial position of the cutting edge rotating surface of the cutting tool 11, the inside of the metal tube 3 The spiral groove 13 is formed on the wall surface.

By adjusting the contact pressure between the blade of the cutting tool and the inner wall surface of the metal tube, it is possible to easily adjust the depth of the groove and easily form the portion with and without the groove.

[0021]

Second Embodiment A second embodiment of the present invention will be described in detail below with reference to the drawings. The second embodiment described below omits the description of the configuration and operation common to the first embodiment, and only different points will be described.

FIG. 3 is an enlarged sectional view of the portion A in FIG. 1 showing the second embodiment of the present invention.
3A shows a state before processing the spiral groove, FIG. 3B shows a state where the spiral groove is not processed, and FIG. 3C shows a state during processing the spiral groove. Part A of the second embodiment is the first die 15
And a second die 17, and the second die 17 is configured to be movable in the axial direction. Further, the thin rod 6 is, similarly to the first embodiment, a cutting bite 11 having a blade at its tip and a metal pipe whose outer diameter is rotatably attached so as not to move in the axial direction. A hollow cylindrical sleeve 16 is attached, which is approximately equal to the inner diameter of 3.

Next, a method of spiral groove machining according to this embodiment will be described. First, the thin rod 6 is inserted into the metal tube 3, the cylindrical sleeve 16 is aligned with the bearing portion 18 of the first die, and the cutting tool 11 is rotated at a predetermined speed,
The metal tube 3 is pulled out in the direction of the arrow in the drawing through the first die 15 at a predetermined speed. At this time, the wall thickness of the metal tube 3 is accurately defined by the first die 15 and the cylindrical sleeve 16. Further, when an annealed copper tube is used as the metal tube 3, the temper suitable for cutting the inner spiral groove is adjusted due to the size of the reduction by the first die 15 and the cylindrical sleeve 16. In order to obtain the above effects, it is desirable that either the first die 15 and / or the cylindrical sleeve 16 can be moved in the axial position.

The metal pipe 3 that has passed through the first die 15 is further reduced in its inner diameter (and outer diameter) by the second die 17 to a size suitable for the inner surface spiral groove machining.

Then, the axial position of the metal tube 3 of the second die 17 is moved so that the position of the cutting edge of the cutting tool 11 and the position of the bearing portion of the second die 17 coincide with each other. A spiral groove 13 is formed on the inner wall surface of the.

Although the second embodiment uses two dice, a plurality of dice can be used.

Further, the first embodiment and the second embodiment described above
A modification of this embodiment will be described with reference to FIGS. 4 and 5.
In this modified example, instead of the dies used in the above two embodiments, a rotating ball die 20 is used that uses a plurality of balls 19 that rotate around the metal tube 3 in a planetary shape and contract. . A roll may be used instead of the ball 19.

The use of this rotary ball die 20 has the effect of significantly reducing the frictional resistance with the metal tube 3. Further, a pair of conical rings 21 is used to hold the sphere 19 and transmit the processing force and the rotational force,
By making the size of the gap between the two freely changeable during the rotation of the ball 19, the inscribed circle when the ball 19 rotates, that is, the contracted tube diameter of the metal 3 can be changed arbitrarily. Therefore, it is not necessary to change the axial position of the rotary ball die 20.

[0029]

As described above, according to the method for processing an inner surface spiral grooved tube of the present invention, a thin rod in which the outer surface of the metal tube is connected by a die and the inner surface of the metal tube and a cutting tool are connected by a cylindrical sleeve. Therefore, the spiral groove can be easily and accurately machined on the inner wall surface of the metal tube by cutting.

[Brief description of drawings]

FIG. 1 is an overall view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing the first embodiment of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a modification of the first embodiment of the present invention.

FIG. 5 is a sectional view showing a modification of the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Die holder 2 Dice 3 Metal tube 4 Carriage 5 Drawing device 6 Thin rod 7 Rotary head 8 Drive device 9 Rotary joint 10, 16
Cylindrical sleeve 11 Cutting tool 12, 14,
18 Bearing part 13 Inner surface spiral groove 15 1st
Dies 17 Second dies 19 Balls 20 Rotating ball dies 21 Rings

Claims (7)

[Claims] 1. A cutting groove is inserted into a metal pipe, and relative rotation and axial feed are given to the cutting tool and the metal pipe to provide an inner wall surface of the metal pipe with a spiral groove in a direction orthogonal to the metal pipe axis. In the method of cutting, the metal tube is drawn through a die provided in a drawing device, the cutting bit attached to the tip of a thin rod is inserted from the rear end of the metal tube to the drawing position, Machining an inner spiral grooved pipe characterized by forming a spiral groove on the inner wall surface of the metal pipe by rotating a cutting bite to match the drawing position of the die and the cutting edge of the cutting bite. Method. 2. The method for processing an inner surface spiral grooved pipe according to claim 1, wherein the drawing position of the die is moved to the cutting edge of the cutting bit to match the drawing position of the die with the cutting edge of the cutting bit. 3. The inner surface spiral groove according to claim 1, wherein a cylindrical sleeve having an outer diameter substantially equal to the inner diameter of the metal pipe pulled out by the die is attached near the tip of the thin rod. How to process pipes. 4. The n dies capable of moving in the axial direction are arranged on the same axis at a predetermined interval, and a metal tube is pulled out through the n dies, and n−1 dies are provided. N-1 cylindrical sleeves having an outer diameter substantially equal to the inner diameter of the drawn metal tube are attached to the thin rod in a rotatable state so as not to move in the axial direction, and the thin rod. A processing means having a cutting tool slightly smaller than the diameter of the n-1 cylindrical sleeve from the previous stage is attached to the tip of the tube from the rear end of the pipe, and the n-1 dies and the n-1 The positions of the individual cylindrical sleeves are aligned with each other, and the metal pipe is subjected to a drawing process to reduce the outer diameter and the wall thickness. Allow the metal tube to be pulled out. It allows processing method with the inner surface helical grooves tube and forming a spiral groove in the inner wall surface of the metal tube. 5. The method for processing an inner surface spiral grooved pipe according to claim 1, wherein the die is a rotary die composed of a plurality of planetary balls or rolls. 6. A spiral groove processed portion and an unprocessed portion are formed at predetermined positions on the inner wall surface of the metal pipe by changing the positional relationship between the drawing position of the metal pipe and the cutting bit in the die. A method for processing an inner surface spiral grooved tube according to claim 1 or 2. 7. The cutting depth of the cutting tool into the inner wall surface of the metal tube is adjusted by changing the positional relationship between the cutting tool and the drawing position of the metal tube in the die. 2. The method for processing an inner spiral grooved tube according to 2.