JPS6284833A - Spiral type dieless bending method - Google Patents

Abstract

PURPOSE:To enable the small radius high frequency heating dieless bending without any nodal build-up and recessed dent at the bending start spot by reducing the bending radius gradually while in bending. CONSTITUTION:A tube 1 is heated by high frequency heating coil 8 by gripping the tube 1 with the tube gripping device 2 and by gripping the other end with a tube end clamp 4 as well, and further the cooling is performed with spraying water by a tube cooling device 9 just behind the heating part. When the temp. of the heating part of the tube 1 reaches to the bending temp., the tube 1 is started to be fed in the arrow mark direction by actuating the tube feeding device 3. Accordingly the tube 1 is started to be bent from the position of the bending center A. The distance between the bending center A and bending center axis phi1 is approached by actuating a bending arm fulcrum moving device 13 and by moving a bending arm fulcrum clamping device 12 in the direction of the high frequency heating coil 8, namely, the bending center A. The bending is thus performed with taking the bending radius at bend starting time larger and reducing it gradually while in bending.

Description

DETAILED DESCRIPTION OF THE INVENTION A [Object of the Invention] (1) Field of Industrial Application The present invention relates to an improvement in a spiral dieless bending method.

(2), Conventional technology In conventional high-frequency dieless bending processing of pipes, etc., the third
As shown in the drawings and FIG. 4, one end of the tube 01 is gripped by a tube gripping device 02, and the other end is gripped by a tube end clamp 04. Next, a high frequency power source (not shown) is activated, the tube 1 is heated by the high frequency heating coil 08, and water is sprayed immediately after the heating section by the tube cooling device 09 to cool it down. When the temperature of the heated part of the tube 1 reaches the bending temperature, the tube feeding device 03 is activated and the tube 1 starts to be fed in the direction of the arrow, but one end of the tube 1 is supported by the bending arm 05. Since the tube 1 is held by the tube end clamp 04, the tube 1 receives a bending moment and is heated by the high-frequency heating coil 08, and only the portion where the strength has decreased is bent by bending center axis φ and the distance φ1A between bending center A as radius. The bending process is performed at the specified curvature. Then, the tube feeding device 03 is operated continuously, and the tube O
1 in the direction of the arrows, it is possible to perform a 90° bending process with a radius of φ1A as shown in FIG.

Figure 5 shows the condition of the small radius bending (bending radius = 2.0 D or less) part of the pipe in the conventional bending method described above. A bump-like bulge C was formed on the periphery, and a concave dent d was formed on the outer periphery, making it unsuitable for use as a bent product.

(3) Problems to be solved by the present invention The problem to be solved by the present invention is to eliminate the drawbacks of the above-mentioned prior art. The following table shows the relationship between the hump height H at the bending start part and the bending radius obtained through experiments. Although only the bump height H is shown here, since the concave dent d becomes smaller as the bump height H becomes smaller, only the bump height H is shown here. According to this table, it can be seen that as the bending radius increases, the bump height H decreases, and when the bending radius becomes 2.5D or more (D is the diameter of the pipe), bumps C hardly occur.

[Structure of the Invention] (1) Means for Solving Zero Problems The present invention was proposed in order to solve the drawbacks of the above-mentioned conventional examples. The problem is to solve the problem of the configuration of the spiral dieless bending method, which is characterized by performing bending while changing the bending center of the pipe, that is, the distance from the bending arm fulcrum, in the direction of approaching it during bending. This is intended as a means of resolving this issue. From the table above, it can be seen that in order to eliminate the bump-like bulges C and concave dents d that occur at the bending start part, the bending radius at the start of bending needs to be large.

Now, when changing the bending radius in dieless bending, it is done by changing the distance between the bending center axis φ and the bending center A without changing the radius of the bending arm. This will be explained using Fig. 6. Fig. 6 is a diagram explaining the principle of high-frequency dieless bending. In the figure, 01 is a tube, A is the bending center, 05° 05' is a bending arm, φ, α, φ1
b is the bending center axis, φ2α.

φ6, φ"', and φ6' indicate the clamping position, and α and b indicate the shape of the bent portion, respectively.

Now, in this figure, the bending radius is ``summer'' and ``summer 6'' is 5, and we consider the case where the bending radius Aφ, (L == 4 and 1p, b = a. In the former case, the bending part has the shape of the solid line α In the latter case, the bent portion is bent into the shape of a solid line.

That is, even if the bending arm length is the same, bending with different bending radii is possible. At this time, there is no device to fix this distance between the bending radius τ and qb, and there is a completely free space.

From the above, during the bending process, change the bending center axis from φ, " to φ1, set a large bending radius at the beginning of the bending process, gradually move the bending center axis closer to the bending process center, and reduce the bending radius. By performing the bending process while maintaining the bending process, it is possible to perform a small radius bending process without a bump-like bulge or a concave dent at the bending start part.The present invention is based on this principle.

(2) 9 Effects The method of the present invention has the above-mentioned configuration as its gist, and exhibits special effects as will be described in detail at the top of the description of the embodiments to be described later.

(3) EXAMPLE Hereinafter, the method of the present invention will be specifically explained with reference to FIGS. 1 and 2. In these figures, 1 is a tube, 2 is a tube gripping device, 3 is a tube feeding device, 4 is a tube end clamp, 5 is a bending arm 5α is a bending arm support pin, 5b is a tube end clamp support pin, and 6 is a guide roller. , 7 is a high frequency transformer, 8 is a high frequency heating coil, 9 is a tube cooling device, 10 is a cable with cooling water, 11 is a bending arm fulcrum moving table, 12 is a bending arm fulcrum clamping device, 13 is a bending arm fulcrum moving device, φ1 indicates the bending center axis, φ2 indicates the clamp rotation axis, and A indicates the bending center, and these members are arranged in the relationship shown. Note that the arrow gin indicates the feeding direction of the tube l.

Next, embodiments of the method of the present invention will be described.

In FIGS. 1 and 2, a tube 1 is gripped by a tube gripping device 2, and the other end is gripped by a tube end clamp 4. Next, a high-frequency power source (not shown) is activated, the tube 1 is heated by the high-frequency heating coil 8, and the tube 1 is further cooled by spraying water with the tube cooling device 9 immediately after the heating section. When the temperature of the heated portion of the tube 1 reaches the bending temperature, the tube feeding device 3 is activated and the tube 1 begins to be fed in the direction of the arrow gin. As a result, the pipe 1 begins to bend from the bending center A.

At the same time as the pipe feeding device 3 is activated, or a little later, the bending arm fulcrum moving device 13 is activated, and the bending arm fulcrum clamping device 12 is moved in the direction toward the high-frequency heating coil 8, that is, the center of the bending process. bending center A
and the distance between the bending center axis φ□ is made closer. As a result, the bending radius can be set large at the start of bending and gradually reduced during the bending process.

In FIGS. 1 and 2, the bending center axis φ□ is brought closer to the bending center A in the direction orthogonal to the tube 1, but the direction in which it is brought closer may be arbitrary.

C [Effects of the Invention] As described above, the present invention has a large bending radius at the start of bending and gradually reduces the bending radius during bending. The practical effect is that small-radius, high-frequency dieless bending without upward or concave dents becomes possible.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the situation before bending according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the situation after the bending process, and Fig. 3 is an explanatory diagram of the situation before the conventional high-frequency dieless bending process. , FIG. 4 is an explanatory diagram of the situation after the processing, FIG. 5 is an enlarged explanatory diagram of the processing part, and FIG. 6 is an explanatory diagram of the principle of high frequency dieless bending. DESCRIPTION OF SYMBOLS 1... Pipe, 2... Tube gripping device, 3... Tube feeding device, 4... Tube end clamp, 5... Bending arm, 5α
... Bending arm support pin, 5b... Tube end clamp support pin, 6... Guy R roller, 7... High frequency transformer, 8... High frequency heating coil, 9... Tube cooling device,
IO...Cable with cooling water, 11...Bending arm fulcrum moving frame, 12...Bending arm fulcrum clamping device,
13...Bending arm fulcrum moving device, φ1...Bending center axis, φ2...Clamp rotation axis, A...Bending processing center. Sub-agent Patent attorney Teru Ito (2 others) Figure 3 Figure 5 Procedural amendment (voluntary) February 3, 1985 Director General of the Patent Office Michibe Uga 1, Indication of the case 1985 Patent application No. 223835 No. 2, Relationship with the name of the invention case Patent applicant address 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Name
(620) Mitsubishi Heavy Industries, Ltd. 4, sub-agent address: 2-29-6 Toranomon-chome, Minato-ku, Tokyo 105
Contents of the amendment Figure 2 of the drawings will be corrected as shown in the attached sheet.

Claims (1)

[Claims] A high-frequency dieless bending method for pipes, etc. is characterized in that the bending process is performed while changing the distance between the high-frequency heating coil and the bending center of the pipe, etc., that is, the bending arm fulcrum, in a direction in which they approach each other during the bending process. Spiral dieless bending method.