JP4044789B2 - How to drill a pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pipe drilling method for drilling a thick wall portion of a pipe.
[0002]
[Prior art]
Conventionally, this type of pipe drilling method includes cutting with a drill (drill), fusing using laser or plasma, or inserting a mandrel 2 into the pipe 1 as shown in FIG. A punching process using the punch 3 is generally known.
[0003]
However, the above-described method for drilling pipes has problems that the pipe is slightly crushed or has burrs or burrs on its surface, resulting in poor sealing performance when packing seal is performed near the hole.
Further, cutting with a drill and fusing using laser or plasma have a problem that processing time is required and fine chips, sputtered scraps and the like are generated.
Further, in the press punching process, the mandrel 2 may not be inserted depending on the bending shape of the pipe 1 or the processing position of the hole, and if the punching is performed without using the mandrel 2, the hole processing part is crushed. There is a problem.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems, and the object of the present invention is not to crush the hole processing portion, to generate burrs, burrs and chips, and to process the hole. It is an object of the present invention to provide a pipe drilling method capable of reducing time.
[0005]
[Means for Solving the Problems]
That is, according to the drilling method of the present invention, a closed electric circuit is formed by bringing the tip end surface of the punch to which voltage is applied into contact with the pipe surface, and the punch end surface is pushed into the pipe, and the punch is brought into contact with the pipe. By heating the contact portion of the pipe with the punch by resistance heating, punching out the contact portion of the softened pipe with the pressing force of the punch, and forming the hole in the pipe, the contact portion of the pipe is punched at the same time , The energization to the punch is stopped.
[0006]
As described above, the drilling method of the present invention heat-softens the drilled portion of the pipe to reduce the shear strength and punches the hole in this state, so that the drilled portion of the pipe is not crushed. In addition, it is possible to reduce the time required for drilling without generating burrs on the periphery of the hole, burrs on the hole surface, and fine chips. Further, at the same time as the punch hits the hole, the energization to the punch is stopped, and the discharge in the pipe due to the disconnection of the energization path is avoided, and the deformation of the hole due to the discharge can be avoided.
[0007]
In the pipe drilling method of the present invention, it is preferable that the tip surface of the punch is flat. By using such a flat punch, the shear point moves sequentially from the top to the outside on the curved surface of the pipe, so that the energization current concentrates on the shear point and heat is generated efficiently.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 4 show an example of a method for drilling a pipe according to the present invention. Here, a method for drilling a wall surface of a cylindrical steel pipe is shown.
[0009]
That is, as a method for drilling the pipe 11, first, as shown in FIG. 1, the pipe 11 is supported in a horizontal state by the pipe receiver 12, and the punch 13 having a flat tip surface 13a is directed downward on the pipe receiver 12. Arrange. In this case, a voltage is applied from the power source 14 between the pipe receiver 12 and the punch 13, and an electric circuit including the pipe receiver (receiving electrode) 12, the pipe 11, the punch (punch side electrode) 13 and the power source 14 is configured. The
[0010]
Next, the punch 13 is lowered in the vertical direction toward the position where the hole of the wall surface of the pipe 11 is made, and pressed with a force that does not cause crushing. At this time, when the tip end surface 13a of the punch 13 contacts the top of the curved surface of the pipe 11, the electric circuit is closed and a current A flows from the power source 14 to the pipe 11, and the contact portion of the pipe 11 with the punch 13 by resistance heating. Is locally heated and softened, and the shear strength of the pipe 11 is lowered. Then, as shown in FIG. 2, the sheared portion 11 a of the pipe 11 moves outward, and the entire tip end surface 13 a of the punch 13 comes into contact with the wall surface of the pipe 11. In this case, since the tip end surface 13a of the punch 13 is formed flat, the shearing portion 11a sequentially moves outward from the top on the curved surface of the pipe 11, and the energizing current A concentrates on the shearing portion 11a, and the contact The part will be heated efficiently.
[0011]
Further, when the punch 13 is continuously pushed, as shown in FIG. 3, the movement of the shearing portion 11a of the pipe 11 proceeds, and the shearing of the contact portion extends over the entire thick portion, and is soon punched as shown in FIG. Then, a hole 11 b is formed in the wall surface of the pipe 11.
[0012]
Here, when a discharge occurs in the pipe 11 after the punch 13 punches out the hole 11b, the shearing surface is melted and the roundness of the hole 11b is lowered. Therefore, in the present invention, the displacement of the punch 13 is detected by a position sensor (not shown), and the energization is controlled at the same time that the hole 11b is punched out. That is, as shown in FIG. 5, energization is started when the position sensor detects the position (S) at which the punch 13 contacts the pipe 11, and energized when the position sensor detects the position (E) where the hole 11b is punched. The energization is controlled so as to stop.
A timer is used in place of the position sensor. When the punch 13 comes into contact with the pipe 11, the energization is started at the same time as the energization is started, and the time is increased after a predetermined time required for completing the punching of the hole 11 b. You may make it stop.
Further, as shown in FIG. 6, the shear strength of the pipe 11 starts to rapidly decrease from around 500 ° C. Therefore, it is preferable to set the heating current A so that the temperature of the contact portion of the pipe 11 with the punch 13 is 500 ° C. or higher.
[0013]
As described above, in the pipe drilling method according to the embodiment of the present invention, since the hole 11b is opened at the moment when the shear strength is reduced while being heated while being pressed by the punch 13, the pipe 11 is not crushed and the pipe 11 is not crushed. 11 roundness can be maintained. Further, since a mandrel as in the prior art is not required, it can be applied to drilling a complex hollow structure. In addition, the processing time is about 1/10 of the press punching at room temperature, and there is no need for cleaning because there is no generation of fine chips or spatters like drilling, and no processing oil is required. . Moreover, drilling with a resistance welder is possible, equipment costs are low, and mass productivity is excellent.
[0014]
Next, the present invention will be described more specifically with reference to examples.
A pipe made of steel (STKM 11A) having a diameter of 12.7 mm and a thickness of 1.2 mm was used as the pipe 11, and this was supported in a horizontal direction by a chrome copper pipe receiver 12 having a curvature radius of 6.9 mm. Using a spot welding machine made of φ8.0 mm copper tungsten having a flat tip surface, the punch 13 was electrically connected to the pipe receiver 12 and the punch 13 to apply a high voltage at a frequency of 5 cycles / min.
When the punch 13 was pushed vertically downward into the wall surface of the pipe 11 with a pressure of 240 kgf and the application of voltage was stopped at the moment when the pipe 11 was drilled, no steel scrap was generated and the roundness of the pipe 11 was maintained. It had been. The energizing current of the pipe 11 was 11,000A.
[0015]
The present invention is not limited to the pipe drilling method shown in the above embodiment, and various modifications can be made without departing from the spirit of the invention described in the claims.
For example, in the embodiment, the front end surface 13a of the punch 13 has a flat shape. However, as shown in FIG. 7, the front end portion 15a may have a stepped shape. It is effective in narrowing. Moreover, although the pressing force of the punch 13 to the pipe 11 varies depending on the material of the pipe 11, it is generally in the range of 100 to 500 kgf, and preferably in the range of 200 to 300 kgf.
The shape of the pipe is not limited to a cylindrical shape, and the cross-sectional shape may be, for example, a quadrangle or an ellipse. The material of the pipe is not particularly limited as long as it is a metal or alloy having a high electrical resistance and characteristics according to various uses. Moreover, examples of the material of the pipe receiver include chromium copper and beryllium copper alloy, and the punch is usually made of copper tungsten.
The pipe drilled in the present invention is used as a gas supply pipe connected to a gas inlet provided in a gas control device such as a gas cock or a gas valve attached to a gas appliance.
[0016]
【The invention's effect】
As can be understood from the above description, according to the present invention, a hole can be drilled in a short time while maintaining the roundness of the pipe without the occurrence of burrs on the periphery of the hole or burrs and chips on the pipe surface. Can do.
[Brief description of the drawings]
FIG. 1 shows an example of a method for drilling a pipe according to the present invention, wherein (a) is an explanatory view showing a state when a punch is in contact with the pipe, and (b) is orthogonal to (a). It is explanatory drawing seen from the direction.
2A is an explanatory view showing a state in which a sheared portion of a pipe is expanded outward from the state shown in FIG. 1, and FIG. 2B is an explanatory view of FIG. .
3A is an explanatory view showing a state where a shear point of the pipe has further moved from the state shown in FIG. 2, and FIG. 3B is an explanatory view of FIG.
4A is an explanatory view showing a state where pipe drilling has been completed from the state shown in FIG. 3, and FIG. 4B is an explanatory view of FIG.
FIG. 5 is an explanatory diagram showing the timing of starting and stopping energization of the pipe shown in FIG. 1;
FIG. 6 is a graph showing the relationship between the shear strength of a pipe and the heating temperature.
FIG. 7 is a front view showing the tip of another punch used in the pipe drilling method according to the present invention.
FIG. 8 is an explanatory view showing an example of a conventional method for drilling a pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Pipe, 11a ... Shearing location, 11b ... Hole, 12 ... Pipe receiver, 13 ... Punch, 13a ... Tip surface, 14 ... Power supply.

Claims (3)

A closed electrical circuit is formed by bringing the tip of the punch to which the voltage is applied into contact with the pipe surface, and the pipe is in contact with the punch by resistance heating accompanying the contact between the punch and the pipe while pushing the tip of the punch into the pipe. When heating the part and punching out the contact part of the softened pipe with the pressing force of the punch to form a hole in the pipe, at the same time that the contact part of the pipe is punched , the energization to the punch is stopped. A method for drilling pipes.   2. The pipe drilling method according to claim 1, wherein a front end surface of the punch is flat. The pipe drilling method according to claim 1 or 2 , wherein the pipe is used as a gas supply pipe connected to a gas inlet of a gas control device in a gas appliance.

Images