JPS6238153Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a processing device for heat exchanger tubes for heat exchangers.

2. Description of the Related Art Conventionally, a heat transfer tube for a heat exchanger is expanded by inserting a large-diameter plug into the inside of the tube and then crimped into the hole of the fin on the outside.

By the way, by forming grooves or the like on the inner surface of such heat transfer tubes, it is possible to increase the heat transfer area and improve the performance of the heat exchanger.

Therefore, in recent years, an apparatus has been proposed for forming grooves on the inner surface of a heat transfer tube and expanding the grooves. All such devices have a structure in which a tool for forming grooves and expanding the tube is fixedly attached to the tip of the shaft. Therefore, when forming a spiral groove on the inner surface of a heat transfer tube and expanding it, the tool must be rotated together with the shaft.

[Problems to be solved by the invention] In such a technology, it is necessary to have a mechanism for moving the shaft in the axial direction as well as a mechanism for rotating it around the axis. Due to the combination structure of both mechanisms, there was a problem that the device itself became complicated.

This idea was made in consideration of the above circumstances, and is equipped with a plug that is a tool for forming grooves and expanding pipes, and is rotatable about the shaft, and the plug is moved in accordance with the thrust of the shaft in the axial direction. A simple structure that does not require a special mechanism for rotating the plug as a tool, allows the plug to rotate extremely smoothly and automatically without significant resistance. The present invention provides a processing device for a heat exchanger tube for a heat exchanger that can expand the tube while forming a shaped groove.

[Means for Solving the Problems] This invention relates to a processing device for heat exchanger tubes for heat exchangers. This processing device has a shaft that is moved in the axial direction inside the heat exchanger tube.
A plug whose maximum diameter is larger than the inner diameter of the heat exchanger tube is attached so as to be rotatable relative to the shaft around the axis of the shaft, and the tip of the plug is tapered and without,
The diameter of the plug is increased smoothly from the tip end to the maximum diameter part, and the diameter is decreased smoothly from the maximum diameter part to the rear end part, so that the rear end part is connected to the maximum diameter part. By forming the plug to have a smaller diameter than the above, the circumferential surface of the plug has a continuous curved surface that changes smoothly from the tip end to the rear end, and furthermore, the circumferential surface of the plug has a large number of protrusions that are inclined with respect to the axis. It is composed of strips.

[Example] This invention will be described below based on an illustrated example.

First, to briefly explain the heat exchanger tube for a heat exchanger, it is a tube body (hereinafter referred to as a "tube body") through which a heat exchange medium such as water, ammonia, or fluorocarbon flows, as shown by reference numeral 1 in the figure. ), and the tube body 1 is made of a copper tube or an aluminum tube with high thermal conductivity. The tubular body 1 is bent into a U-shape, inserted into holes 3 formed in a large number of fins 2 made of aluminum plates, etc.
Multiple pieces are arranged at equal intervals.

The processing device of this invention performs processing on such a tubular body 1.

The processing device has a plug 4, which has a tapered main body whose maximum diameter is slightly larger than the inner diameter of the tubular body 1, and a curved surface that swells smoothly around the maximum diameter. ing. As is clear from Fig. 2, near this maximum diameter part, the diameter expands smoothly from the tip side (right side in the figure) of the plug 4, and decreases smoothly towards the rear end side (left side in the figure). The end side is formed to have a smaller diameter than the maximum diameter portion, and the circumferential surface of the plug 4 is a continuous curved surface that smoothly changes from the tip end to the rear end. Also, on the outer peripheral surface of the plug 4, a large number of protrusions 5 are formed that are slightly inclined with respect to the axis of the main body (incline so that the right side is downward from the left with respect to the axis in Fig. 2). has been done. A through hole 6 is formed in the main body of the plug 4 along its central axis, and a shaft (mandrel) 7 is inserted into the through hole 6. 8 and is rotatably attached by a nut 9. The shaft 7 is inserted into the tube 1 described above along its axial direction.

Next, the action of the plug of this processing device will be explained.

This processing device press-fits the plug 4 at the tip into the tube 1 inserted into the hole 3 of the fin 2 by moving the shaft 7. As a result, the plug 4 expands the tubular body 1, and the protrusions 5 on the circumferential surface of the plug 4 bite into the inner surface of the tubular body 1. Since the area near the maximum diameter of the plug 4 is curved, the tube expands gradually.
Further, the protrusions 5 gradually bite into the inner surface of the tube body 1. Since the protrusions 5 are inclined with respect to the axis of the plug 4, the thrust of the shaft 7 in the axial direction generates a rotational force in the plug 4 itself. This rotational force causes the plug 4 to move toward the shaft 7.
It rotates around its axis. Therefore, axis 7
Due to only the linear movement of the tube body 1, the spiral grooves 10 are formed on the inner surface of the tube body 1 while being expanded.

In this way, the maximum diameter portion of the plug 4 simultaneously performs the action of expanding the tube body 1 and acting as a grooving tooth on the inner surface of the tube body 1; As described above, the diameter of the plug 4 increases smoothly from the tip end and decreases smoothly toward the rear end, so that the rear end side is formed to have a smaller diameter than the maximum diameter part, and the circumferential surface of the plug 4 extends from the front end to the rear end. Because it is a continuous curved surface that changes smoothly towards the end,
Groove 10 while expanding the pipe without large resistance...
It rotates extremely smoothly while forming a .

By the way, when you try to expand a pipe using a plug, the inner diameter of the pipe body 1, which the top of the plug's largest diameter part touches, expands to a greater extent than the diameter of the plug's largest diameter part (for copper pipes with a diameter of about 10 mm). If 2/
100 to 3/100mm), but when the leading part of the largest diameter part passes, it spreads too much (2/100 to 3/100mm)
A phenomenon occurs in which the duct is constricted, and as a result,
There is a problem in that the inclination angles of the grooves in the expanded state and the contracted state are very slightly different. This mechanism is understood to occur as the sum of strains occurring in the tube axis direction and circumferential direction during tube expansion.

Under such a phenomenon, if the diameter of the plug 4 is made to be the same from the maximum diameter part to the rear end of the plug 4, the plug A relatively wide area having the same diameter from the maximum diameter portion of tube body 1 to the rear end of tube body 1
This causes a large frictional force to act on the inner surface of the plug 4, creating a large resistance when the plug 4 rotates, and not only does it no longer function as a tube expansion or grooving tooth, but if the plug 4 is pushed forcibly. This may cause problems such as bending the tube body 1 itself.

However, in the plug 4 of the present invention, the maximum diameter part does not have a constant width, and the diameter smoothly decreases toward the rear end, so that the frictional force at the time of tube contraction is suppressed as much as possible. 4 can be rotated smoothly without giving any resistance.

In addition, if the tube body 1 is a copper tube with an inner diameter of 8.8 mm and a wall thickness of 0.41 mm, the intervals between the grooves 10 on the inner surface are
They are formed as 0.3 mm (approximately 90 peaks), 0.46 mm (approximately 60 peaks), and as small as 0.23 mm (approximately 120 peaks). Further, the inclination angle of the protrusions 5 formed on the plug 4 is the same as that of the bearing 8,
Due to the effect of No. 8, etc., the angle is limited to a range of 7° to 30°.

In this way, a large number of spiral grooves 10 are formed on the inner surface of the cylindrical body 1 as the tube expands, and at the same time as the tube expands, it is crimped into the holes 3 of the fins 2 and is fitted therein by interference fit. Fastened and fixed. After that, the plug 4 is moved backward and the plug 4 is removed from the pipe body 1.
pull out. In this case, if the maximum diameter part of the plug 4 has a constant width, since the tube body 1 is slightly contracted as described above, when the plug 4 is retreated, the tube body 1 with the groove formed therein However, the plug 4 of the present invention has problems such as accidents where the rear end of the plug is stuck on the inner periphery of the plug, and smooth reversing is not possible.
Since the rear end side is gradually and smoothly made smaller in diameter than the maximum diameter part, it is possible to prevent galling and smooth retraction of the plug 4.

After the plug 4 is moved back and removed from the tubular body, the communicating tubes 11 bent in a semicircular arc shape are attached to the fixed tubular body 1 to make the respective tubular bodies 1 communicate with each other.

When a heat exchange medium is allowed to flow through the tubular body 1 thus formed, the heat exchange medium flows in a turbulent state due to the spiral grooves 10 carved on the inner surface of the tubular body 1. The heat exchange medium has a good heat exchange rate, and furthermore, heat is efficiently conducted to the fins 2 through the tube body 1. Further, since the spiral grooves 10 are not cut in the bent portion of the tubular body 1 and the inner surfaces of the communication tubes 11..., the heat exchange medium flows in this portion in a laminar flow state. Therefore, in this part, the heat exchange medium flows without colliding with the inner surface of the tube body 1, and the surface corrosion products (oxide film) are not mechanically peeled off, and the heat exchange medium is free from corrosion due to corrosion. Tube 1
There is no need to worry about wear or damage.

[Effects of the invention] As explained above, the apparatus for processing heat exchanger tubes for a heat exchanger according to the invention is equipped with a plug that is a tool for expanding tubes and is rotatable about the shaft. It has a structure in which a large number of protrusions are formed that are inclined with respect to the axis, and the plug is automatically rotated by the thrust of the shaft in the axial direction, so pipe expansion can be performed simply by moving the shaft linearly in the axial direction. Since the spiral groove can be formed very easily and no special mechanism for rotating the plug as a tool is required, the configuration of the device itself can be simplified.

Moreover, the diameter of the plug is reduced smoothly from the maximum diameter part to the rear end part, and the rear end part is formed to have a smaller diameter than the maximum diameter part, creating a continuous curved surface that changes smoothly. Therefore, the frictional force during pipe expansion is reduced, the plug rotates smoothly without large resistance, the pipe expansion action and groove formation action are performed smoothly, and the plug can be smoothly retreated. effective.

[Brief explanation of the drawing]

Fig. 1 is a front view of a heat transfer tube for a heat exchanger, Figs. 2 and 3 show an embodiment of this invention, and Fig. 2 is an enlarged sectional view showing a state in which a plug is press-fitted into a straight section of the tube body. , FIG. 3 is a view taken along the - line in FIG. 2. 1... tube body, 2... fin, 3... hole, 4...
Plug, 5... Projection, 7... Shaft, 10... Groove, 1
1... Connecting pipe.

Claims (1)

[Scope of utility model registration request] A plug, the maximum diameter of which is formed to have a larger diameter than the inner diameter of the heat exchanger tube, is placed on a shaft that is moved in the axial direction inside the heat exchanger tube. The plug is mounted so as to be rotatable relative to the shaft, the tip of the plug is tapered, and the diameter of the plug increases smoothly from the tip to the maximum diameter portion, and the plug has a tapered tip. The circumferential surface of the plug is made smooth from the tip to the rear end by reducing the diameter smoothly from the tip to the rear end so that the rear end has a smaller diameter than the maximum diameter part. A processing device for a heat exchanger tube for a heat exchanger, characterized in that the plug has a continuous curved surface that changes, and further has a large number of protrusions that are inclined with respect to the axis on the circumferential surface of the plug.