JPH04313418A - Method and device for working inside surface grooved tube - Google Patents

Abstract

PURPOSE:To manufacture the grooved inside surface of a tube for a heat exchanger at a low cost and in a stable state by forming a working head by piercing a nozzle hole for supplying and injecting high pressure working oil on a spherical projecting part, and executing the working by pressure of the working oil. CONSTITUTION:To a metallic conduit 12, lubricating oil is pressed in from its end tube, and also, a floating plug connected so as to be rotatable with a tie-rod and a grooved plug 25 having a trapezoidal groove are inserted. Subsequently, by pointing the tube end, a pointed part is formed, and thereafter, this pointed part is allowed to pass successively through a hydraulic rolling part of a first die, and a diameter shaping die, and clamped to a drawing device. Next, working oil of low pressure is supplied to a working head, the drawing device is driven, while rotating the working head, and grooving is performed by raising gradually a drawing speed and working oil pressure to a stationary state. In such a way, a grooved tube in which surface roughness is small, a working mark scarecely exists, and the surface quality is satisfactory is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming grooves on the inner surface of metal tubes made of copper, aluminum, etc. used as heat exchanger tubes for heat exchangers in air conditioners and refrigerators.

0002

[Prior Art] In recent years, metal tubes made of copper, aluminum, etc. with internal grooves have been used as heat transfer tubes for heat exchangers in air conditioners, refrigerators, etc. There is a demand for products with internal grooves of various shapes. Conventionally, a method for manufacturing such an internally grooved tube has been disclosed in Japanese Patent Application Laid-open No. 5
As disclosed in No. 4-37059, JP-A-55-103215, etc., rolling pressure drawing is one of the so-called tube shrinking groove processing methods that form grooves on the inner surface of a processed metal tube while shrinking it. There are processing methods.

[0003] As shown in FIG. 5, this tube reduction compaction method
While grasping the tip of the metal tube 21 with a chuck (not shown) and pulling it out, the first die 22 and the floating plug 2 are removed.
3 to reduce the diameter of the metal tube 21 by pressing it from the outside, and then using a planetary rotating member 24 such as a rolling roll or a rolling ball placed around the outer periphery of the metal tube 21 to create a grooved plug that has been installed in the tube in advance. The grooved tube 21 is manufactured by pressing the inner surface of the metal tube 21 against the tube 25 and forming grooves on the tube inner surface.

[0004] In addition, in order to counter this tube reduction compaction method, a metal tube 21 as shown in FIG. While expanding the metal tube 21, the inner surface of the tube is grooved in cooperation with a planetary rotating member 24 such as a rolling roll or a rolling ball placed on the outer periphery of the metal tube, thereby forming an inner grooved tube with fewer inner surface defects. A method has been proposed.

[0005]

[Problems to be Solved by the Invention] As described above, even with the above-mentioned conventional technology, it is possible to continuously process an internally grooved tube with few internal defects by cooperating the grooved plug and the planetary rotating member. there were. However, in all of the above conventional techniques, the metal tube is compressed between the grooved plug and a planetary rotating member such as a rolling roll or a rolling ball placed on the outer periphery of the metal tube in the area where the grooved plug is located, thereby providing boundary lubrication. Since this method processes internally grooved tubes in the same state, it is necessary to rotate the rolling member at a speed that corresponds to the drawing speed of the metal tube in order to process high-quality internally grooved tubes with high productivity. ,
Recently, in order to further improve productivity, a method has been adopted in which the rotation speed of the rolling member is increased to 20,000 to 30,000 revolutions per minute.

[0006] Therefore, as the rolling member rotates at a higher speed, it is necessary to improve the precision of each part of the rotating head, and this causes problems such as an increase in manufacturing costs and a shortened life of the planetary rotating member. Ta. It is an object of the present invention to provide a method and apparatus for processing internally grooved tubes that can solve these problems and process high quality internally grooved tubes at lower cost and with high productivity using a simple configuration. There is.

[0007]

[Means for Solving the Problems] The above object is achieved by the method and apparatus for processing an internally grooved tube as set forth in the claims, but the inventor of the present application has basically made the following points in his invention. Technical considerations were made from these points of view.

[0008] ■ The head structure is simplified by using only revolving members to process the pipe instead of the method in which the tube to be processed is rolled and pressed by rotating at high speed like a rolled ball. ■ A high-pressure medium is interposed between the workpiece and the pipe to be processed, and processing is performed without metal contact or sliding friction.

As a result, we succeeded in solving the above problem using the following method. That is, a plurality of spherical protrusions are provided inside a donut-shaped rotating ring, a nozzle hole is provided for supplying high-pressure machining oil from the inside of the protrusion, and the pipe to be processed is processed by the pressure of the machining oil injected from the nozzle hole. This is a method of machining an internally grooved tube by continuously pressing the same grooved plug as in the prior art.

0010

[Example] Specific processing conditions for carrying out the present invention were studied, and examples were constructed based on the following viewpoints. (a) The ratio of the curvature R of the spherical protrusion inside the rotating ring to the radius r of the pipe to be processed is R/r=1.45 for the following reason.
It is preferably in the range of 1 to 2.076. That is, R
If /r is small, the thinning rate of the raw material product will be large, making it difficult to form small fins with a peak height of 0.15 mm or more and a peak angle of 45° or less. On the other hand, if R/r is too large, the number of spherical protrusions is limited to a small number, and the entire processing tool becomes large and heavy, making it unsuitable for high-speed rotation and making it difficult to maintain high productivity. (b) The number of spherical protrusions is required to be three or more to prevent the metal tube from escaping during processing of the grooved tube, and from the above R/r relationship, three to five are preferable. (c) The pressure applied to the machining oil injected from the nozzle hole drilled in the spherical protrusion shall be such that the dynamic pressure pv at the nozzle exit is greater than or equal to the yield stress of the metal pipe to be machined and less than its rupture stress. It is preferable to set the optimum pressure by performing test machining using the calculated value as a guide.

FIG. 1 is a diagram showing an axial cross section of a processing device for an internally grooved tube according to the present invention and a processing oil system, and FIG.
FIG. A ring having multiple spherical protrusions on the inner surface is fixed to the tip of a hollow shaft that is rotated directly by an electric motor, hydraulic motor, etc. or via a belt, etc., and high-pressure machining oil supplied from the outside is supplied to the protrusions into the pipe to be processed. A nozzle hole is drilled to inject water into the pipe, and the dynamic pressure required for grooving the pipe is rotated at a speed that matches the drawing speed of the pipe to be processed and does not leave any unprocessed parts. Machining oil at the given pressure is supplied from a hydraulic pump through a non-rotating cylindrical ring provided on the outer periphery of this rotary machining ring while sealing the gland part with a decompression chamber and a shaft seal, and the machining oil is injected from the nozzle hole. Grooving is performed by pressing the pipe to be processed against the grooved plug located in this nozzle portion.

In FIG. 1, the gaps between the disks of the rotary ring 1 for introducing high-pressure machining oil and the grinding ring (non-rotating) 2 for preventing leakage of high-pressure machining oil are brought into a mating state, and when the machining oil passes through this rubbing surface, I'm trying to reduce the pressure. In addition, so that the pressure in the left and right decompression chambers 3 is always maintained at the same pressure, the two chambers are connected by a pipe line, and at the same time, the relief oil pressure regulating valve 13 is used to maintain a constant low pressure. This reduces the thrust force generated in the head 8 and prevents pressure from being applied to the gland packing 6 during machining.

The inventor of the present invention actually processed a grooved tube using the apparatus of the present invention, and the results will be described below. <Processing conditions> Processing pressure 100kg/cm2
Decompression chamber pressure 10kg/cm
2 Processing speed 60m/m
In machining head rotation speed: 20,000 rpm Under the above conditions, an annealed P-deoxidized copper tube with an outer diameter of 13.0 mm and a wall thickness of 3.5 mm was machined to an outer diameter of 9.52 mm and a wall thickness of 0.5 mm.
A trapezoidal grooved tube with a diameter of 36 mm, 60 grooves, and a lead angle of 18° was manufactured.

First, in the apparatus and processing process shown in FIG. 3, lubricating oil is injected into a metal tube (raw tube) 21 from its end tube, and a floating plug 23 rotatably connected by a tie rod 27 and an outer diameter of 10.20 mm are attached. , a grooved plug 2 having a trapezoidal groove with a groove depth of 0.20 mm and a number of grooves of 60.
5 was inserted. Next, the pipe end is subjected to tip machining to form a mouth part, and then this mouth part is passed through a first die 22 with an exit hole diameter of 10.90 mm, a hydraulic compaction processing part with an inscribed circle diameter of 10.50 mm, and an outlet. The preparation work was completed by sequentially passing through a diameter-adjusting die 28 with a hole diameter of 9.58 mm and clamping it to a drawing device (not shown).

[0015] After completing the above preparatory work, 1
Supply machining oil at a low pressure of about 0 kg/cm2, drive the pull-out device while rotating the rolling head, start the pull-out process, and then gradually increase the pull-out speed and machining oil pressure to reach a steady state. Grooving was performed.

[0016] As a result, it was possible to stably produce a tube with quality equal to or higher than that of the internally grooved tube rolled using conventional balls or rolls. In particular, with this method, the machining head and the metal tube surface are machined in a good condition with no metal contact or sliding friction between the two through a high-pressure oil film, resulting in low surface roughness and good surface quality with almost no machining marks. A grooved tube was obtained. Furthermore, it was confirmed that even during continuous operation, the life of the processing head is more than twice that of the conventional one.

Although this example was carried out under the conditions of reducing the diameter of the metal tube with a rolling head and forming grooves, the present invention is not limited to this. It is also applicable to the attachment method.

Although FIG. 1 shows a system in which the rotary head 8 having a spherical protrusion on the inside is driven by an electric motor or a hydraulic motor, there is another method in which the rotary head 8 is driven by the energy of processing oil as shown in FIG. It is also possible to inject machining oil from the high-pressure machining oil injection nozzle 9 of the rotary head 8 while rotationally driving the turbine blade 15 attached to the rotary head 8 to perform grooving.

In this case, since it is necessary to adjust the flow rate and pressure of the machining oil in order to give the rotating head 8 the necessary number of rotations, the high-pressure machining hydraulic pressure adjustment valve 12 on the pump machine side is used as a safety valve, and the rotation It is important to have a circuit configuration in which the head 8 is provided with a relief oil pressure regulating valve 13 that maintains a flow rate relief function.

[0020]

[Effects of the Invention] As described above, according to the present invention, the following effects can be achieved as explained in the above embodiments. ■
Compared to the conventional rolling groove processing method using balls or rolls, the grooved tube with particularly good surface quality remains stable for more than twice as long as the conventional method, and the drawing speed is equal to or higher than the conventional method. This makes it possible to manufacture with high productivity. ■ Manufacturing costs can be significantly reduced compared to conventional methods. ■ It can be applied to either the tube contraction rolling method or the tube expansion rolling method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an axial cross section of a processing device for an internally grooved tube according to the present invention (one half of the cross section is shown in a plane including a rotational axis) and a processing oil system.

FIG. 2 is a sectional view taken along the line a-a in FIG. 1;

FIG. 3 is a diagram showing a processing apparatus and a processing process for an internally grooved tube according to the present invention.

[Fig. 4] Cross section of a rotating head having a structure different from that in Fig. 1 (
FIG. 3 is a diagram showing a cross section taken along a plane including the rotation axis and showing a half of the cross section) and a system of processing oil.

FIG. 5 is a diagram showing a processing process of a grooved tube by a conventional tube shrink rolling method.

FIG. 6 is a process diagram for processing a grooved tube using a conventional tube expansion and rolling method.

[Explanation of symbols]

1 Rotating ring for introducing high-pressure processing oil 2 Grinding ring for preventing leakage of high-pressure processing oil (non-rotating) 3 Decompression chamber (thrust balance chamber) 4 Grinding ring pressing pressure adjustment spring 5 Grinding ring pressing pressure adjustment bolt 6 Gland packing 7 Bearing and gland Seal fixing sleeve 8 Rotating head for metal pipe machining 9 High pressure machining oil injection nozzle 10 Rotating head drive shaft 11 High pressure machining oil supply pump 12 High pressure machining oil pressure adjustment valve 13 Relief oil pressure adjustment valve 14 Excess high pressure machining oil relief valve 15 Turbine Blade 16 Guide blade 17 Bearing 20 Workpiece metal tube 21 Metal tube (base tube) 22 First nozzle 23 Floating nozzle 24 Planetary rotating member (rolled ball or rolled roll) 25 Grooved plug 26 Grooved tube 27 Tie rod 28 Adjustment diameter die

Claims (7)

[Claims] 1. A metal tube is reduced in diameter with a processing die and a floating plug, then a groove is formed on the inner surface of the metal tube with a rotating ring-shaped member and a grooved plug, and the metal tube is further reduced in diameter with a diameter adjustment die. In a method for grooving the inner surface of a metal tube in which the diameter is adjusted and the tube is continuously contracted or expanded by rolling pressure drawing, a plurality of spherical protrusions are provided on the inside of a rotating ring-shaped member, and the spherical protrusions are subjected to high-pressure processing. A processing head is formed by drilling a nozzle hole for oil supply and injection, and the metal pipe to be processed is pressed against the grooved plug by the pressure of the processing oil injected from the nozzle hole to process the internally grooved pipe. A method for processing an internally grooved tube. 2. A reduced diameter part of a metal tube consisting of a drawing die and a floating plug, and a plurality of spherical protrusions on the inside, and a nozzle for supplying and spraying machining oil approximately at the center of the spherical protrusions. Consisting of a processing head with a hole, a grooved processing section consisting of a rotating ring-shaped member and a grooved plug disposed outside the processing head, and a diameter adjustment section consisting of a diameter adjustment die. A processing device for pipes with internal grooves. 3. The dynamic pressure at the outlet of the nozzle hole of the machining oil ejected from the nozzle hole bored in the spherical protrusion is set within a range equal to or higher than the yield stress of the pipe to be processed and less than the tensile strength of the pipe to be processed. The method for processing an internally grooved tube according to claim 1. 4. The internally grooved tube according to claim 2, wherein the ratio of the radius of curvature R of the spherical protrusion to the radius r of the tube to be processed is in the range of R/r=1.45 to 2.076. Processing equipment. 5. The apparatus for processing an internally grooved tube according to claim 2, wherein the number of spherical protrusions is three or more. 6. The apparatus for processing an internally grooved pipe according to claim 2, further comprising means for rotating the processing head having a spherical protrusion on the inside by an electric motor, a hydraulic motor, or the like. 7. The apparatus for machining an internally grooved tube according to claim 2, wherein the machining head having a spherical protrusion on the inside thereof is rotated by energy supplied from machining oil.