JPS5952026B2 - ERW pipe manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a case of an iso-heater core used in an electric resistance welded pipe manufacturing device applying a high-frequency induction heating method or a high-frequency resistance heating method. The purpose is to improve welding efficiency during welding.

In other words, it relates to an ERW pipe manufacturing device that can increase the welding pipe manufacturing speed when a certain amount of power is consumed during welding of steel pipes, etc., and can reduce the power consumption when the welding pipe manufacturing speed is constant. It is. In the case of high-frequency induction welding, which is a generally known conventional method for improving the welding efficiency of steel pipes by high-frequency welding, impedance matching between the high-frequency power source and induction heating coil, selection of ferrite magnetic material for the impeder, and frequency characteristic Improvements include bringing the impeder core closer to the inner wall of the steel pipe, and cooling the isoheater core to suppress the rise in heat generation temperature due to high-frequency magnetic loss.

The overall effect of the above is to improve welding efficiency, but
These countermeasures are mutually contradictory conditions with respect to cooling the impeder core, making it difficult to improve welding efficiency.

That is, as shown in FIG. 5, in the conventional device, when the distance d between the outer peripheral surface of the impeder core and the inner wall of the steel pipe is reduced to bring the impeder core 3 closer to the inner wall of the steel pipe, the isoheater core is enclosed for cooling the impeder core 3. If you try to arrange the isoheater case 9 and circulate the cooling fluid in order to make it difficult to arrange the impeder case 9 and to ensure reliable cooling, the distance d between the outer peripheral surface of the impeder core and the inner wall of the steel pipe will increase. Therefore, there was a problem that the effects of improving welding efficiency canceled each other out. In addition,
Here, it is known that when the pipe manufacturing speed is taken as a specific expression value of welding efficiency and the relationship with the distance d between the outer circumferential surface of the impeder core and the inner wall of the steel pipe is shown as shown in FIG. 1. The shaded area in the figure is the ideal operating region. In addition, even if the material of the ferrite core is selected and improved, the high-frequency magnetic loss of the isoheater core will be affected by the impeder core's heat generation temperature rising by about 100 degrees Celsius when operating in a high-frequency electromagnetic field of several 100 KW. To compensate for temperature characteristics, cooling with cooling water, etc. is required. The present invention effectively solves the above problems, and the configuration thereof will be explained below.

FIG. 2 is a perspective view of an electric resistance welded tube manufacturing apparatus/equipment showing one embodiment of the present invention, and FIG. 3 is a side sectional view of the same.

FIG. 4 is a cross-sectional view taken along the plane AA' shown in FIG.
FIG. 5 is a sectional view taken along the plane A--N corresponding to FIG. 4 of the conventional device. In the figure, 1 is a steel pipe to be welded, 2 is an in-heater case 3 is an in-heater core made of ferrite, and these constitute the inside of the pipe. fluid is moved.

Reference numeral 5 denotes an induction heating coil connected to a high frequency power source 6, and a cutting tool for removing burrs generated during welding of steel pipes, which constitute the outside of the pipe.

Conventional technology uses an appropriate compromise between the distance d between the outer peripheral surface of the in-heater core and the inner wall of the steel pipe and the pipe thickness of the in-heater case 9 made of molded resin such as Bakelite, Teflon, or epoxy-impregnated glass wool. Ta.

Therefore, in order to obtain the maximum pipe forming speed included in the ideal region as shown in Figure 1, the distance d between the in-heater core outer circumferential surface and the steel pipe inner wall should be set to a value larger than the value in the ideal value region. As a result, the amount of power corresponding to the difference between the actual value and the ideal value becomes a loss, and it has long been desired to reduce this power loss. J. To compensate for the drawbacks of the in-heater case made of resin, the in-heater case is made of about 80 to 90 wt% of ferrite magnetic powder, which has low high-frequency magnetic loss similar to that of the in-heater core 3, and chloroprene rubber, styrene rubber, etc. There is an inner heater case molded from a mixture of 20 to 10 wt% of resin such as rubber material or plastic, but the welding efficiency at the initial stage of welding is not improved compared to the case using a conventional non-magnetic case. However, in a short period of time, heat generation from the in-heater and burnout due to welding flash occurred, and the efficiency was not much different from that of conventional non-magnetic cases, making it impossible to perform stable and highly efficient welding.

By the way, the electric resistance welded pipe manufacturing apparatus according to the present invention overcomes the above-mentioned drawbacks of the conventional one. A magnetic in-heater case is made of the same material as the in-heater core, which is made of a mixture of ferrite magnetic powder with low high-frequency magnetic loss and a resin such as epoxy, reinforced with glass fiber to improve mechanical strength and heat resistance. It is characterized by the fact that it enables highly efficient and stable welding.

In this way, by using the in-heater case 2 mainly made of ferrite, the distance d between the outer peripheral surface of the in-heater core and the inner wall of the steel pipe in the conventional device can be effectively reduced to the value indicated by the horizontal axis in FIG. It is almost equivalent to the distance d'' between the outer wall of the in-heater case 2 made of magnetic material and the inner wall of the steel pipe of the electric resistance welded pipe manufacturing equipment, and the ideal area of d is set by d'', and the mechanical strength and heat resistance are It was also possible to obtain sufficient performance and overcome all the drawbacks of conventional devices.

Therefore, the in-heater case 2, which is mainly made of ferrite, serves as a case that serves as a pipe wall for the path of the cooling fluid 4, and also secures the ideal region d shown in FIG. becomes possible. Exception: In the case of a steel pipe with a diameter of 25.4 mm and a wall thickness of 1.2 mm, the power is 75 KW and the length is 2.
00mm, outer diameter 1 for an in-heater core with a diameter of 12mm.
A magnetic case made of the glass fiber of the present invention, 15 wt% of resin, and 85 wt% of ferrite was used as an in-heater case of 9 mm and an inner diameter of 16 mm, and a conventional Teflon-based non-magnetic case and a rubber or resin of 15 wt% and 85 wt% of ferrite were used.
Figure 6 shows that the welding efficiency is improved by 20%, which is extremely high compared to the conventional magnetic case that is not assisted by glass. It has become clear that stable and highly efficient welding is possible.

In Fig. 6, curve A is the case when an in-heater case made of glass fiber, plastic, and ferrite powder is used, and curve B is the case when an in-heater case made of rubber or plastic ivy and ferrite powder is used. C shows a case where an in-heater case made only of resin is used.

As is clear from the above embodiments, in the electric resistance welded tube manufacturing apparatus of the present invention using the in-heater case 2 made of a mixture of a magnetic material, glass fiber, and resin, the arrangement of the in-heater case 2 is easier than in the conventional apparatus. The pipe manufacturing speed has been improved by about 20%, that is, the welding efficiency has been improved compared to the previous method, contributing to a reduction in pipe manufacturing costs and making it possible to realize a stable manufacturing process.

In other words, in welded pipe manufacturing, welding costs account for a major proportion of the manufacturing costs, and the electricity consumption costs account for the majority of the welding costs, so it is clear that this invention will reduce the cost of manufacturing, and it will be a major factor in this industry. We believe that it has made a significant contribution and is timely, considering today's energy situation.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the arrangement of the inner heater and the pipe manufacturing speed, Fig. 2 is a perspective view of the ERW pipe manufacturing apparatus of the present invention, Fig. 3 is a sectional view of the same side, and Fig. 4 is a line A of Fig. 3. FIG. 5 is a sectional view of a portion of the conventional device corresponding to FIG. 4, and FIG. 6 is a diagram showing the relationship between welding efficiency and time.

Claims (1)

[Claims] 1. In an electric resistance welding pipe manufacturing apparatus by high frequency heating welding having an impeder core and an impeder case enclosing the impeder core, the impeder case is made of a mixture of magnetic powder, glass fiber, and resin that has low high frequency magnetic loss. An ERW pipe manufacturing device featuring: