JPS5947112A - Inside-surface grooving for expanded pipe - Google Patents

Abstract

PURPOSE:To permit grooving by means of a guide jig and a cutter, for example by driving a chisel by hammering with an air hammer onto the thick part of a heat-transmitting pipe expanded, and cutting said thick part along the axis center from inside. CONSTITUTION:A collared guide jig 5 equipped with a dovetail-groove-shaped guide groove 6 is inserted into the pipe edge part of an expanded heat-transmitting pipe 4. A chisel 7 having a V-shaped sheare point 8 is inserted into the guide groove 6. When said chisel 7 is driven by hammering with an air hammer (not shown in the figure), the expanded thick part is cut. Therefore, the heat- transmitting pipe 4 groove-cut is drawn-out from the insertion hole 2 on a pipe plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method for cleaning the inner surface 114 of an expanded tube.

The heat transfer section of a pressure vessel such as a boiler or heat exchanger is composed of a large number of heat transfer tubes installed in parallel. It is appropriate to use a so-called expander to expand the diameter of the tube from the inside of the tube sheet, and then firmly fix the tube sheet and the outer wall of the tube. That is, this state is as shown in FIG. 1, and in the upper half from the center line 2 in the figure, when the groove 3 is formed in the insertion hole 2 of the tube sheet 1 and the heat exchanger tube 4 is expanded, The lower half shows the case where the heat exchanger tube 4 is expanded directly into the insertion hole 2, and the tube end is 10 to 15 mm.
The dimensions after mm 6fJ are expanded in a trumpet shape,
In the former case, the groove 3 is used to extract the heat exchanger tube 4 from the insertion hole 2.
It is necessary to deform it inward as much as it is pushed into the hole, and it is easier to pull it out in the latter case. In addition, here the first
The medium method related to the expanded band shown in the figure has a pipe diameter of 3
8~50nun+ The thickness of the tube sheet is about 30~150mm.

Now, in boilers and heat exchangers like this, when used for a long period of time, the inside of the heat exchanger tube becomes 1m long.

The outer surface may be eroded by 1M, or foreign matter may accumulate, and as a result, the heat exchange action becomes subsoil, which may eventually lead to rupture.Therefore, it becomes necessary to replace these heat exchanger tubes. ? 3 (S must be quickly contained. At this time, if the diameter of the heat exchanger tube is approximately 25 mm or less, it is possible to forcefully pull it out, but if the tube diameter is about 38 to 100 mm, , so it cannot be removed from the tube 1. Especially when the insertion hole has a groove like the one shown in Aft, it is difficult to remove it because it is embedded in the thick part of the heat exchanger tube.

Conventional 1 In such cases, the thick part of the expanded band is cut from the inside along the axis by gas welding at one or several places in a 11' line, and this part is crushed and deformed before being pulled out. However, even if I try to renoor the groove by the thickness of the heat transfer tube, there is a risk that the insertion hole in the tube plate will be damaged by the gas flame, so it is not desirable to leave the damaged insertion hole as it is. Even if you replace it with a new heat exchanger tube and expand it again, the scratches are grooves in the axial direction, so it will be impossible to maintain airtightness from now on! , becomes.

This invention is an attempt to improve the above-mentioned drawbacks of the conventional technology. It is an object of the present invention to provide a method for mechanically grooving using a tool.

In order to achieve this object, the present invention uses a guide jig that is inserted completely inside the end of the heat exchanger tube, and a chisel that is inserted into the guide groove of this guide jig. The grooves are cut by driving with an air hammer or the like.

WJ groove cutting is done to make the wall thickness of the pipe end as deep as possible and to avoid any damage to the insertion hole, and the groove shape has a notch effect that makes it easy to crush after cutting the groove. Shape 1 For example, a sharp V-shape is ideal, and the appropriate length of the groove is about the thickness of the tube plate. And in this way, when cutting t: (as much as 1.2 mm), and there is considerable variation depending on how tightly the extension band is tightened6. This will ultimately result in a change in the depth of the groove.As for the depth of groove cutting, as mentioned above, cut as deep as possible without penetrating the pipe wall.In other words, cut the groove as deep as possible without penetrating the pipe wall. It is desirable to cut the material thinly, but for practical purposes, it is advantageous for the thickness to be 0.5 mm or less in order to facilitate the subsequent crushing operation.

Hereinafter, one embodiment of the method of the present invention will be described in detail with reference to FIGS. 2 to 7. In these FIGS. or a considerable portion thereof.

FIG. 2 is a longitudinal sectional side view showing the cutting state in this embodiment, and FIG. 3 is a front view with a portion thereof cut out by 9 grooves. As is clear from these figures, in this embodiment, a flanged guide jig 5 having a dovetail-shaped guide groove 6 is fitted into the tube end of the expanded heat transfer tube 4, and the guide groove 6. By inserting a chisel 7 with a V-shaped cutting edge 8 and hitting it with an air hammer (not shown) as shown by the arrow, the expanded thick part is cut. be.

Figure 4 shows the case where four equally spaced cut grooves 9 are machined on the inner peripheral surface of the tube end in this manner, and in this state, the trumpet-shaped part of the tube end is tapped as shown by the arrow in the figure. By this,
The expanded band portion including the turning portion is crushed as shown by the chain line, and the heat exchanger tube 4 can be pulled out from the insertion hole 2 of the tube plate 1. Here, the points at which the cut grooves 9 are added are not limited to many, but are naturally determined depending on the conditions at the work site.

However, when the groove cutting and pressure is applied, if there is a difference in the inner diameter of the end of the heat transfer tube 4 after expansion due to tolerances and there is a gap between it and the guide jig 5, the A guide jig as shown in FIGS. 6 and 7 may be used.

That is, the guide jig 5 shown in FIG. 5 has a wedge surface 10 formed on the opposite side of the guide groove 6, into which a wedge 11 is removably driven and fixed. In this case, the relative position of the guide jig 5 fixed within the tube end of the heat transfer tube 4 with respect to the inner surface of the tube deviates by the amount of play, so the absolute position of the cutting edge 8 of the chisel 7 with respect to the inside of the tube [nj Change. In other words, the depth of the cut groove 9 to be cut also changes, so in order to correspond to this and process the cut groove 9 to a predetermined depth, several types of blades 7 with different cutting edge heights are prepared.
You will have to choose from them.

Further, the guide jig 5 shown in FIGS. 6 and @7 has a guide groove 6
A notch 12 having a large diameter shape and latching onto the axis is formed on the opposite side of the flange, and a screw hole 13 is formed on the flange side, and a guide groove 15 corresponding to the guide groove 6 is formed on the opposite side of the flange. and an end plate 14 having a shaft hole 16 formed therein which coincides with the notch 12, is fixed with a set screw 17, and 6f an eccentric roller 18 is placed in the notch 12, and its threaded portion 19 is inserted into the screw hole. 13, its shaft 31 < 20 +ifj mark shaft hole 16
The eccentric roller 1
8th episode! 1ilJ and the locking nut 22 at its rotational position.
It was made to be fixed by indigenous people.

Of course, in this case, as in the 1f1 example, 7 is selected and used.

Below-1- As explained in detail, when using the method of this invention,
In order to remove the heat exchanger tubes that are expanded and fixed in the insertion holes of the tube sheet, when cutting grooves on the inner surface of the expanded tube ends, insert a guide jig all the way inside the tube ends. At the same time, since this is done by driving a chisel with a sharp edge into the guide groove formed in this guide jig, unlike the conventional method of cutting scraps, the insertion hole of the tube plate is cut. There is no damage to the inner surface, so it is possible to reliably maintain airtightness even after replacing the heat exchanger tubes. I tried to make it more crowded, so (sword f
It is possible to add the heat exchanger tubes as deeply and accurately as possible, making it extremely easy to assemble the heat exchanger tubes, and the addition process itself is simple and does not involve any danger. It has excellent features such as:

By the way, the dimensions related to the extract band section targeted here are nominal (・1, pipe diameter 38 to 5 mm mln +
The thickness of the tube sheet is approximately 30 to 150 mm. .

[Brief explanation of the drawings] Figure 1 shows the expanded heat exchanger tube and tube sheet fixed together.
Fig. 2 is a vertical side view showing a groove cutting state according to an embodiment of the IJ1 method, and Fig.
Figure 4 is a partially cutaway front view, Figure 4 is an explanatory diagram showing how the heat exchanger tubes are stored, and Figure 5 is a perspective view showing a specific example of the guide jig and chisel. Figure 6 is the same as 1. A perspective view showing another specific example, and FIG. 7 is a diagram showing its usage state. 1 tube plate, 2 insertion hole, 4 heat exchanger tube, 5' guide jig,
6 ・Guide groove, 7 Chisel, 8 Sword tip, 9 Cut'IP
g. Patent applicant Takashi Suzu, patent attorney for Hiki Kikuryoku Co., Ltd. - Figure 5 Figure 6

Claims (2)

[Claims] (1) A method of cutting grooves on the inner surface of the expanded tube end high 1 in order to replace heat transfer tubes expanded and fixed in insertion holes of tube sheets in boilers, heat exchangers, etc. A guide jig is inserted all the way inside the tube end to position and fix it, and a chisel with a sharp cutting edge is placed in the guide groove formed along the axis of this guide jig. The internal groove of the expanded Q'+ is characterized by cutting grooves to match the wall thickness of the tube end. (2) A method for grooving the inner surface of an expanded pipe according to claim 1, characterized in that the cut grooves are cut in multiple and circumferential positions.