JPS61286018A - Method and device for manufacturing inner surface grooved tube - Google Patents

Abstract

PURPOSE:To improve the working speed and the productivity by providing a floating plug having no bearing surface, also forming an inner surface groove by welding by pressure plural balls to the outer surface of a grooved plug, and also providing a hourglass-shaped roll. CONSTITUTION:With respect to the first die 3, the second rotary die 4 is provided, and also a floating plug 2 which has only an approach surface 31 and does not have a bearing surface is provided in a tube stock 22. The floating plug 2 to which a grooved plug 1 is set is inserted into the tube stock 21 filling a lubricating oil, pointing is executed and a continuous groove working is executed by operating a drawing equipment. In this case, the pipe 21 is reduced as to its diameter and becomes the tube 22, and a groove working is executed by the rotary die 4 and the grooved plug 1. The diameter reduction is executed by plural ball groups 9 which rotte at a high speed, therefore, the total drawing resistance decreases. Since the grooving is executed at a high speed, the working speed of a product is also improved, and the productivity is improved.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method and apparatus for forming axial or spiral grooves on the inner surface of a metal tube such as a heat transfer tube, and particularly to The present invention relates to a method for manufacturing an internally grooved tube and an apparatus therefor, which can improve productivity.

"Prior art and its problems" In recent years, there has been a strong demand for higher performance for heat transfer tubes in the field of heat exchangers from the viewpoint of energy and resource conservation. Metal tubes are now frequently used in heat exchangers that undergo a phase change inside the tubes, and there is a growing demand for low-cost supplies.

Generally, when manufacturing a metal tube that has axial (parallel to the tube axis) or spiral grooves on the inner surface of the tube (hereinafter referred to as an inner grooved tube), a material tube with a large outer diameter is drawn and contracted. diameter,
While drawing, axial or spiral continuous grooves are formed on the inner surface of the drawn tube, but in this method, the resistance force due to the drawing process and the resistance force due to the groove process are combined. It has drawbacks such as polymerization, which requires extremely high drawing force, which causes breakage and heat generation, making it difficult to process into thin materials and making it impossible to form deep grooves.

This is because, in the manufacturing process of such internally grooved tubes, the resistance force in the diameter reduction process and the resistance force in the internal groove process are combined as described above, and the resistance force is significantly greater than that in the general drawing process whose purpose is only to reduce the diameter. This is because a resistance force is generated, and it is not possible to reduce the resistance force simply by combining conventional drawing techniques, etc., and it is necessary to find a means that can reduce the drawing force the most and have high productivity.

For example, FIG. 2 shows that a tube 102 has a fixed die 105 having an approach surface 110 and a bearing surface 107, and a fixed die 105 that is accommodated within the tube 102 and has an approach surface 110 and a bearing surface. 107
After performing a diameter reduction process between the floating plug 106 having the approach surface 111 and the hair ring surface 108 parallel to the
! Rotatable grooved plug 1 connected by rod 103
12, and a rotating roller 114 that rotates around the grooved plug 1120 and applies volatilization pressure to the inner surface of the tube against the outer peripheral protrusion 113 of the grooved plug 112 to form grooves on the inner surface.

In this case, the die 105 and the floating plug 112
approach surfaces 110 and 111 and bearing surfaces 9 and 10
7. The pipe cannot be drawn unless a large drawing force is applied due to the resistance force of 10B, and the lR process is performed by rubbing the protrusion 113 of the grooved plug 112 against the inner circumference of the pipe to compress the pipe. The frictional force between the continuous projections 113 and the inner periphery of the tube is large, and therefore, on top of the large drawing force caused by the fixed die 105 and the floating plug 106, the resistance force caused by the discontinuous projections 113 is further added, so that the drawing force becomes even larger. However, it was difficult to process thick materials, making it difficult to process complex shapes and deep grooves, and it was not possible to stably process long materials.

The third (!l) is another example of bearing surface 1.
07. While drawing the tube 102 between the fixed die 105 having approach surfaces 110 and 111 and the floating plug 106, the rotary ball 115 is pressed against the tube whose diameter has been reduced by the fixed die 105, and the floating plug 106 is drawn. The tube is pressed against a rotatable grooved plug 112 connected to the rear end to form grooves on the inner surface of the tube, but in both cases, the approach surfaces 110, 111 and the hair ring surface are 107, 108 (the proportion depends on the bearing surface) -47)
Since the resistance force is large and these are polymerized, it is not possible to form thick-walled materials or deep grooves, and even when processing thin-walled materials, the fixed die 105 and the rotating 'roller l], 4
Alternatively, there is a drawback that twisting occurs in the tube between it and the rotating ball 115, making it difficult to process.

In addition, small ripples remain on the outer periphery of the tube whose diameter has been reduced by the rotating rollers 114 and rotating balls 115 shown in FIGS. 2 and 3, and the roundness of the tube is also poor. In order to form the tube later, a die is used to perform a slight diameter reduction process for sizing, but the machining resistance is also large, causing problems such as tube breakage.

``Purpose'' Therefore, the present invention minimizes the resistance force during continuous diameter reduction processing, internal processing, and finishing to a predetermined dimension, and eliminates the drawbacks and difficulties inherent in the above-mentioned conventional methods for manufacturing internally grooved pipes. It is an object of the present invention to provide a method and apparatus for manufacturing an internally grooved tube, which eliminates all problems, enables high-speed machining, and increases productivity.

"Structure of the Invention" The main means adopted by the present invention to achieve the above object is a method for manufacturing an internally grooved tube in which axial or spiral grooves are formed on the inner surface of the tube, which does not have a die or a bearing surface. A tube is passed between the floating plug and the diameter of the tube is reduced by the approach surface of the die, the bearing surface and the approach surface of the floating plug, and then the tube is rotatably connected to the floating plug and has an axial or spiral protrusion on the outer surface. Grooves are formed on the inner surface of the tube by pressing a plurality of balls rotating in the circumferential direction of the tube onto the outer surface of the grooved plug, and then a plurality of drum-shaped rolls rotating in the circumferential direction of the tube are pressed against the tube. This is a method for manufacturing an internally grooved tube, which is characterized by compressing the tube at a position where the grooved plug is removed by compressing the tube at a position where the grooved plug is removed. In this apparatus, a die having an approach surface and a bearing surface is housed in a tube corresponding to the die, and the tube is gripped between the approach surface of the die and the tube is diameter-reduced. a floating plug having an approach surface that substantially has no bearing surface, and a grooved plug rotatably connected to the floating plug via a connecting rod and having an axial or spiral protrusion on the outer peripheral surface; A plurality of balls are provided on the outside of the tube corresponding to the grooved plug and rotate around the tube axis while pressing the tube against the protrusion of the grooved plug to form continuous grooves on the inner surface of the tube, and a grooved inner surface. The present invention provides an apparatus for producing an internally grooved tube, which is equipped with a plurality of drum-shaped rolls that are pressed against the outer periphery of the tube and rotate around the tube axis.

"Embodiments" Next, embodiments embodying the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an embodiment of the present invention, and is a side sectional view showing a specific example of a processing mechanism that can be directly used to carry out the method for manufacturing an internally grooved tube.

The following example is a specific example of the present invention, and is not intended to limit the technical scope of the present invention.

In the processing mechanism shown in Fig. 1, the first die 3 is
0 by the casing 11 and the fixture 44, and after the material tube 21 is reduced in diameter by the die 3, it is pulled out in the direction of the force F as a reduced diameter tube 22. The purpose of this die 3 is to supply the material tube to a second rotating die 4 in a perfectly circular shape. A floating plug 2 having only an approach surface 31 and no bearing surface is mounted inside the material tube 22 to be processed by the second rotary die 4 . Therefore, the approach surface 31 of the floating plug 2 is parallel to the approach surface 32 of the die 4, and in this case, the minimum diameter d that corresponds to the rear end of the approach surface 31 is determined to be smaller than the inner diameter of the pipe 23, which has a diameter of m, immediately after diameter reduction. The structure has substantially no bearing surface in contact with the tube 22.

The floating plug 2 has a shaft 5, which is an example of a connecting rod, extending through it on its central axis, and a shaft 5 at the rear of the shaft 5.
A grooved plug 1 is rotatably supported between a shaft head 46 at the rear end and a rear end surface of the floating plug 2 via a thrust bearing 6. A spare thrust bearing 6' is fixed to the tip of the shaft 5 by a nut 7.

The second rotating die 4 has a curvature in the bearing portion 33 to reduce resistance during drawing.

The diameter-reduced tube z3 is then set integrally with this rotary die 4, and a plurality of ball groups 9 that freely rotate in the circumferential direction of the tube
The tube is further reduced in diameter, and is compressed between the grooved plug 1 held by the floating plug 2 inside the tube, resulting in a tube 24 with grooves formed on the inner surface of the tube.

The rotating die 4 generates drawing resistance due to the processing of reducing the diameter of the tube 22 to form the tube 23 and the friction caused by the floating plug 2 for holding the grooved plug 1 in a fixed position within the tube. Since the floating plug 2 does not have a bearing part and there is no thinning between the floating plug 2 and the die 1, the resistance is smaller than in normal drawing.The die 4 is rotating. also contributes to reducing resistance.

Since the tube 23 is pinched between the ball group 9 and the grooved plug 1, a large resistance is generated at the pinched portion, but the ball group 9
moves in the circumferential direction with respect to the tube 23 at high speed, so the machining point always moves, so the resistance in this machining is also small.

The rotary die 4 and a plurality of ball groups 9 that freely rotate in the circumferential direction of the tube are attached to the constituent member 13 in a detachable and adjustable manner, and the rotation radius of the plurality of ball groups 90 can be adjusted in the circumferential direction with respect to the tube 23. This member 13 is rotatably attached to a mount 12 fixed to the machine base via a bearing 17 to transmit rotation. A gear 37 is provided on the outer periphery, and this gear 37
meshes with the intermediate gear 15.

The intermediate gear 15 is rotatably fixed to the fixing base 14 and meshes with the internal gear 35 of the rotating body 16.

The rotating body 16 is rotatably fixed to the machine base 10 via a bearing 19, and rotational force is transmitted via a pulley 41 from an external power source (not shown).

Therefore, the rotating directions of the rotating body 16, the rotating die 4, and the plurality of ball groups 9 are opposite, and the rotation direction of the internal gear 35 of the rotating body, the intermediate gear 15, the rotating die 4, and the gear 37 of the member 13 including the plurality of ball groups 9 is opposite. Any speed increasing ratio can be obtained by appropriately selecting the respective number of teeth. In this example, the speed of the rotating die 4 is increased compared to the rotating body 16.

The tube 24 processed by the plurality of ball groups 9 leaves small ripples on the surface and has problems with dimensional accuracy, so a rotatable drum roll that can be set at an appropriate angle with respect to the axis of the tube 24 is used. By press-fitting two or more 8 into the tube 24 as a set and rotating them at high speed, the tube 24 is sized and the tube outer diameter and tube outer surface shape are improved.

The drum roll 8 is rotatably fixed to a holder 20 via a bearing 18, and the holder 20 is connected to a tube 24.
The drum roll can be set at an appropriate angle with respect to the axis of the drum, and it also has the ability to adjust the amount of reduction with respect to the tube 24, and is fixed to the rotating body 16.

Rotate the drum roll 8 at high speed in the direction to pull out the tube 24,
When the tube 24 is sized to form the tube 25, the drawing force is significantly lower than in the case of sizing with a die, and the sizing resistance becomes zero or less.

The die 3 is lubricated by continuously dropping it into the pipe 21 from a lubricating oil supply device (not shown), and the rotating die 4 and the plurality of ball groups 9 are lubricated from the base 42 through a passage 43 penetrating the inside of the machine. This is carried out by press-fitting using a single immersion oil supply device (not shown).

The bearing 17 is of a shaft-sealed type, and the rotating die 4
By forming an oil groove 34 on the outer surface of the case, lubricating oil is distributed between the plurality of ball groups 9 behind the rotating die and
The gears 7 and the drum roll 8 are lubricated, and excess oil is discharged to the outside of the rotating body 16 by centrifugal force.

When grooving the inner surface of a pipe using the processing mechanism described above, first a large amount of lubricating oil is poured into the pipe 21, and then the floating plug 2 with the grooved plug 1 set therein is passed through the processing mechanism. It is inserted to a length that reaches the chucking of a drawing device (not shown), a mouth is machined to a diameter that allows it to easily pass through the processing mechanism, and this mouth part passes through the processing mechanism and is chucked into the drawing device. When the processing mechanism is rotated and reaches a predetermined rotational speed, the drawing device is activated to continuously process grooves.

The tube 21 that has started drawing is first reduced in outer diameter using the die 3 to adjust the tube diameter, becoming the tube 22, and then the tube 22.
The diameter of the tube is further reduced by a rotating die 4 which holds a floating plug 4 in the tube and rotates at high speed to form a tube 23, and then the tube is further reduced in diameter by a plurality of balls 9 which also rotate at high speed in the circumferential direction of the tube. The tube is intermittently squeezed between the grooved plug 1 fixed in place by the floating plug 4 to continuously form grooves on the inner surface of the tube 23.

Since the grooved plug 1 is rotatably fixed to the shaft 5 via the thrust bearing 6, even in the case of a 11111M-shaped groove, it can be machined because it rotates freely on the inner surface of the tube.

The drawing force in these processes is caused by the fact that the rotary die 4 rotates at high speed and the bearing part has a curvature, so the frictional resistance on the outer surface of the tube is small, and the floating plug 4 does not have a bearing part on the inner surface of the tube. Since no thinning is applied to the pipe, the resistance is small, and since the groove processing is carried out locally at high speed, the overall resistance is smaller than in the case of bead drawing.

The surface condition of the tube 24 due to groove processing varies depending on the diameter, rotation speed, and drawing speed of the ball used for groove processing.The larger the diameter of the ball, the higher the rotation speed, and the slower the drawing speed, the better the surface condition will be. However, the diameter of the ball is limited by the diameter of the pipe to be machined, and the rotation speed is limited by mechanical strength, so if the surface condition is emphasized, the drawing speed will be sacrificed.

In order to process it economically, it is necessary to increase the drawing speed, and therefore it is necessary to improve the surface condition by some method, and sizing using dies was attempted as described above, but the drawing force increased significantly. .

Therefore, in the present invention, the drawing force is reduced by performing sizing using the freely rotating drum roll 8.

Although only one drum roll 8 is shown in FIG. 1, two
If it is not composed of a set of more than one set, the restriction on the pipe is weak and sizing is difficult.Also, there is an optimum value for the angle with respect to the pipe axis and the diameter of the drum roll, and the angle θ with respect to the pipe axis is in the range of 15 to 45 degrees. The curvature of the drum roll is preferably slightly smaller than the curvature of the ellipse of the projected cross section of the tube to be sized at an angle to the tube axis.

First FI! In the example shown in J, the rotating directions of the ball group 9 that performs grooving and the drum roll 8 are reversed, so that the torsional force acting on the pipe during grooving can be alleviated, making it possible to process difficult-to-process materials or thin-walled materials. It is possible.

By adopting a method of increasing the rotation speed of the groove processing part through the fixed small diameter intermediate tooth N15,
The mass of each rotating part is small, reducing the load on the bearing! ! It is possible to mechanically rotate at high speeds, and because the high speed rotating parts are not exposed, there is less risk of damage even in the event of damage, improving safety.

Figure 4 shows a comparison of the drawing load during internal groove processing in the case of drum roll sizing according to the present invention (when the rotating direction of the drum roll 8 is set in the direction of pulling out the pipe to be sized) and in the case of die sizing. As shown in the figure, it can be seen that in the case of drum roll sizing, there is no drawing resistance at the drum roll portion, and on the contrary, the drawing force is reduced by about 5 to 15 kg.

This is because the drum roll itself applies a drawing force to the pipe, and thus acts to reduce the drawing load in this part.

FIG. 5 shows the drawing load when the rotation direction of the drum roll is the direction of pushing back the tube to be sized, and it can be seen that even in this case, the drawing load can be significantly reduced compared to die sizing.

For reference, the case of die sizing is shown as a dotted line, but the total drawing force in this case is very close to the breaking load, resulting in unstable processing.

In the case of die sizing, the tube is compressed over the entire surface, whereas in the case of drum roll sizing, the tube is always compressed locally. In the former case, the A resistance is only sliding friction, whereas in the latter case, rolling friction occupies most of the A resistance.

In the experiments shown in Figures 4 and 5, a tube with an outer diameter of 9.52φ (0.36mm thickness) was used with a grooved plug having 65 discontinuous protrusions at a helix angle of 25° and a height of 015t. The data is for drawing, and the rotation speed of the drum roll is 3000 rpm, and the drawing speed is 10 m/min.

"Effects of the Invention" As described above, the present invention provides a method for manufacturing an internally grooved tube in which an axial or spiral groove is formed on the inner surface of the tube, in which a tube is passed between a die and a floating plug that does not have a bearing surface. The diameter of the tube is reduced by the approach surface of the die, the bearing surface, and the approach surface of the floating plug, and then the tube is attached to the outer surface of the grooved plug, which is rotatably connected to the floating plug and has an axial or spiral protrusion on the outer surface. A groove is formed in the pipe P3 by press-contacting a plurality of balls rotating in the circumferential direction of the pipe, and then a plurality of drum-shaped rolls rotating in the circumferential direction of the pipe are pressed against the pipe to form a grooved boolug. In a method for manufacturing an internally grooved tube characterized by compressing the tube at a dislocated position and an apparatus for manufacturing an internally grooved tube in which an axial or spiral groove is formed on the inner surface of the tube, the approach surface and the bearing surface are a floating plug that is housed in a tube corresponding to the die, has an approach surface for gripping and reducing the diameter of the tube between the approach surface of the die, and has substantially no bearing surface; A grooved plug that is rotatably connected to the floating plug via a connecting rod and has an axial or spiral protrusion on its outer peripheral surface; A plurality of balls are pressed into contact with the protrusions of the tube and rotate around the tube axis while forming continuous grooves on the inner surface of the tube, and a plurality of drum-shaped balls are press-contacted with the outer periphery of the tube after the inner groove has been processed and rotate around the tube axis. This is a manufacturing device for internally grooved tubes, which is equipped with rolls, and there is no friction resistance due to the bearing part of the floating plug, which regulates the inner diameter in the past, and the tube is pressed against the grooved plug by rotating at high speed. Local machining is carried out continuously using multiple balls, so resistance is small.Furthermore, the sizing of the grooved pipe is carried out by rotating a drum-shaped roll at high speed in the circumferential direction to pull out the pipe. Since a drawing force is generated, the overall drawing force can be reduced.Furthermore, by making the rotation directions of the plurality of balls for grooving and this drum-shaped roll opposite to each other, the torsion that acts on the pipe during grooving can be alleviated. This makes it possible to process the inner surfaces of thin-walled materials and difficult-to-process materials that were previously difficult to process.

Furthermore, by using a means to rotate only the grooved part at high speed, it was possible to increase the carving speed, improving productivity, and also improving safety because the high speed rotating part was not exposed.

In addition, since dies are not used to control and smooth the outer diameter of the tube after grooving, there is no need to prepare expensive dies, and any outer diameter can be obtained without increasing drawing force. can.

In this way, the present invention makes it possible to process difficult-to-process materials and thin-walled materials, which have been difficult to process with internal grooves, and achieve high productivity with 5 inexpensive tools. The present invention provides a highly advantageous method and apparatus for processing pipes.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an apparatus for manufacturing an internally grooved tube according to an embodiment of the present invention, FIG. 2, FIG. 3 is a side sectional view of a conventional apparatus for manufacturing an internally grooved tube, and FIG. , and FIG. 5 are graphs showing the effects of the present invention. (Explanation of symbols) 1... Grooved plug 2... Floating plug 3... Dice 4... Rotating die 5...
・Shaft (connecting rod) 6.6'...Thrust bearing 8・
...Tzumi roll 9...Ball 21, 22, 23
．． 24.25...Tube.

Claims (1)

[Claims] 1. In a method for manufacturing an internally grooved tube in which an axial or spiral groove is formed on the inner surface of the tube, the approach surface of the die is passed between a die and a floating plug having no bearing surface; The diameter of the tube is reduced by the bearing surface and the approach surface of the floating plug, and then the outer surface of the grooved plug, which is rotatably connected to the floating plug and has an axial or spiral protrusion on the outer surface, is rotated in the circumferential direction of the tube. A groove is formed on the inner surface of the tube by pressing a plurality of balls into contact with each other, and then a plurality of drum-shaped rolls rotating in the circumferential direction of the tube are pressed against the tube to remove the grooved plug. A method for manufacturing an internally grooved tube characterized by compression. 2. The method for producing an internally grooved tube according to claim 1, wherein the die is attached to a rotating body holding a plurality of balls that rotate at high speed in the circumferential direction of the tube and rotates together with the rotating body. 3. Claim 1, in which the plurality of balls rotating at high speed in the circumferential direction of the tube rotate at a higher speed than the plurality of drum-shaped rolls.
A method for manufacturing the internally grooved tube described in item 1 or 2. 4. The method for manufacturing an internally grooved tube according to claim 1, wherein the die is a rotating die that is actively rotated about the tube axis. 5. In an apparatus for manufacturing an internally grooved tube in which an axial or spiral groove is formed on the inner surface of the tube, the die has an approach surface and a bearing surface, and the approach surface of the die is housed in a tube corresponding to the die. a floating plug that has an approach surface for gripping and diameter-reducing the pipe between the pipes and substantially has no bearing surface; or a grooved plug having a spiral protrusion, and a tube located on the outside of the tube corresponding to the grooved plug and pressed against the protrusion of the grooved plug to form a continuous groove on the inner surface of the tube while centering the tube axis. A manufacturing device for an internally grooved tube, comprising: a plurality of balls that rotate to rotate; and a plurality of drum-shaped rolls that are pressed against the outer periphery of the tube after being subjected to internally grooved processing and rotate around the tube axis.