JPH0659505B2 - Method and apparatus for manufacturing double curved pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a double bent tube which is often used in a fine chemical plant or the like.

[Conventional technology and its problems]

In fine chemical plants that manufacture soaps, pigments, epoxy resins, etc., double curved pipes and double straight pipes are used where it is necessary to keep the line at a constant temperature. The reason is that, for example, in some organic acids, 60
Since it condenses at ℃ and deteriorates at 150 ℃, the temperature of the line must be controlled so that it is maintained within the intermediate temperature of 105 ± 5 ℃, and for this reason the double curved pipe and double straight pipe are The pipe is used.

Thus, as shown in FIGS. 5 and 6, the conventional method for manufacturing a double curved pipe is as follows. First, the inner pipe is formed by combining the curved pipe member 1 and the straight pipe members 2 and 3 and welding 4 , 5 are joined to make a pipe, and flanges f are welded 6, 7, 8, 9 to both ends.
Further, the portion corresponding to the outer pipe is the curved pipe member 11 and the straight pipe member 1.
Weld 2 and 13 together in the longitudinal direction and weld them by tying them together so as to wrap the already processed inner tube.
Although it is formed on the outer pipe by doing so, actually, in the longitudinal direction, due to the assembly structure of the inner pipe, the split short pipe 18 is welded 19 and 20, and all have a welded structure. Therefore, in addition to the high cost, there are 6 welding points in the inner tube and 10 in the outer tube due to the splitting, and as a whole there are 16 points. In particular, when the pipeline is blocked due to the leak of water vapor, an accident such that the operation of the plant is disabled often occurs at an early stage. Due to such an accident resulting from defective welding, the plant may be stopped and a large-scale repair may be required. Therefore, the operation must be stopped for a long period of about half a year to one year. The loss due to this is immeasurable, and there is a strong demand for improvement of the prior art.

On the other hand, as a method of manufacturing the double bent tube, there is a method previously proposed by the applicant of the present application (see Japanese Patent Publication No. 60-25207).

In the above method, the front and rear ends of the outer tube and the inner tube formed in a double tubular shape are supported by clamps or the like, and the positions of the inductors for heating the outer tube and the inner tube are adjusted appropriately to separate the outer tube and the inner tube. It is designed to be bent with the same bending moment and the same radius. Specifically, by positioning the inductor of the inner pipe slightly forward of the inductor of the outer pipe, the front and rear end parts are supported with a large thickness. The outer pipe and the inner pipe having different lengths are bent at the same bending moment and the same radius.

However, in this method, the lengths of the inner and outer pipes are not adjusted, and the outer pipe and the inner pipe are bent at the same bending moment and the same radius only by appropriately adjusting the position of the inductor back and forth. Therefore, there was some difficulty in producing a good bent double pipe.

[Means for Solving the Problems]

The present invention has been made for the purpose of providing a method and an apparatus for manufacturing a double curved pipe which can solve the above-mentioned problems of the prior art. An outer tube formed into a short shape is combined into a double tube with an appropriate gap between them, and the tips of the inner tube and the outer tube are fixed by flange welding or other appropriate means to keep the two tubes at a fixed interval. , A double tube combined into an integral structure, the inner tube of the double tube is heated from the inner side thereof, and the outer tube thereof is also heated from the outer side thereof simultaneously into a narrow annular shape by high frequency induction heating, and the tip of the outer tube is Clamping the bending arms and the rear ends of both tubes by clamps, and applying an adjustable thrust force to the rear ends of both tubes to continuously bend in the high temperature plastic region by heating. Characterized by , And the addition, the configuration of the device that,
A swivel bending arm that holds the tips of the inner and outer pipes to be made into a double curved pipe by a clamp, and high-frequency induction that heats the inner pipe from its inner side and also the outer pipe from its outer side to a narrow width. An apparatus comprising heating means and clamping means for gripping the rear ends of both pipes and applying a thrust force from the rear, and continuously bending the both pipes in the high temperature plastic region by the heating means, A bending arm for clamping the outer tube of the double tube in which the tip of the tube and the outer tube shorter than the tube are fixed by a flange or other appropriate means, and the rear end of the double tube is separately clamped and thrust is applied. A clamp jig and induction heating means arranged inside the inner tube and outside the outer tube are provided, and the clamp tube has an inner tube and an outer tube that are generated by thermal stress or other influences during the bending process. Jurisdiction Is provided with a control device for appropriately controlling thrust in order to alleviate the strain and residual stress of the pipe, and is detachably inserted between the inner pipe and the outer pipe in order to keep the gap constant. It is characterized by having a guide ring.

〔Example〕

 Next, an embodiment of the method of the present invention will be described with reference to the drawings.

As shown in FIG. 1, one end of the inner pipe 21 and the outer pipe 22 is flanged.
It is fixed to 23 by welding, and these two pipes are combined at a constant interval into an integral structure to form a double pipe, and this double pipe is set in the pipe bending device described later, and the inner pipe 21 is also inserted from the inside to the outside. The pipe 22 is simultaneously heated in a narrow annular shape from the outside by high frequency induction heating, and the lengths of the inner pipe, the outer pipe, or both pipes are adjusted, and continuously bent in a high temperature plastic region to form a double pipe. It is formed into a curved pipe.

In the above, in order to fix only one side of the inner pipe 21 and the outer pipe 22 by welding the flange 23 or the like, during bending, thermal stress or flatness and bending of the bent portion of the inner pipe 21 and the outer pipe 22 Since the difference in the thickness change rate causes the difference in the length of the material consumed in the bent portion, when the bending is performed while restraining both ends, a stress strain is generated in the bent portion, and the inner pipe 21 and the outer pipe 22 are not always required. This is because it may not be bent concentrically, and in order to mitigate the effect of stress strain due to changes in the length direction of the inner pipe 21 and the outer pipe 22, either the inner pipe 21 or the outer pipe 22 The bending thrust can always be optimally controlled in response to changes in the length direction only at the ends.

In addition, when manufacturing a double bent pipe with flanges attached to both ends, usually, the inner pipe 21 is a double pipe longer than the outer pipe 22, after bending, the pipe is removed from the pipe bending device, The inner pipe 21 is attached to the rear straight pipe end by flange 24 by welding, and in order to fill the gap formed between the rear straight pipe end of the outer pipe 22 and the flange 24, If they are joined together, a short tube member 25 divided into two having the same diameter as the outer tube 22 is arranged, and the portions to be joined together are formed into a short tube by welding, and both ends of the short tube are referred to as the outer tube 22. By firmly and watertightly connecting to the flange 24 by welding, as shown in FIG. 2, a double bent tube having flanges 23 and 24 attached to both ends can be obtained.

In the above, the ends of the inner pipe 21 and the outer pipe 22 are flanged.
Although it is fixed to 23, a means capable of firmly gripping both tubes may be adopted.

Next, the device of the present invention will be described.

In FIG. 3, 31 is the flange 23 of the double pipe shown in FIG.
A clamp jig that grips the end on the side of the double pipe is attached to a swingable bending arm 32 that restricts the bending radius of the double pipe, and a hydraulic cylinder 33 is provided. The end portion on the flange 23 side is firmly gripped. 34 is a boss supported by the bending arm 32, 35 is a frame of the pipe bending apparatus main body, and 36 is a bending thrust of the inner pipe 21 which is always kept optimal in response to changes in the length direction of the inner pipe 21 and the outer pipe 22. The hydraulic cylinder for controlling the thrust is hydraulically controlled, but the invention is not limited to this, and a chain, a screw mechanism or the like may be used. 37 is a till body, which is propelled by a hydraulic cylinder, a chain, a screw mechanism, and the like. 38 is mounted on the tilt body 37 so that it can slide only in the front-rear direction, and the hydraulic cylinder 36
Sliding clamp that always controls the thrust of 21 properly, 39 is the inner tube
Hydraulic cylinder for fixing 21 to sliding clamp 38, 40
The outer pipe 22 is clamped and fixed by a hydraulic cylinder 41 with an outer pipe fixing clamp fixedly attached to the till body 37.

42 is a guide roller for guiding the outer tube 22, 43 is a bracket for supporting the guide roller 42, 44 is the bracket 43
A screw for moving the guide roller 42 is adjusted by the screw 44 according to the size of the outer tube 22.
45 and 46 are mounts for the transformers 47 and 48, 49 is an inductor that heats the inner pipe 21 from its inside, 50 is an inductor that heats the outer pipe 22 from its outside, 51 is a high frequency current induced from the transformer 47 Leads for passing through the inductor 49, 52 for the high frequency current from the transformer 48, the inductor 50
It is a lead for passing through.

Reference numeral 53 denotes a guide ring arranged between the inner pipe 21 and the outer pipe 22 so as to optimally maintain the gap between the inner pipe 21 and the outer pipe 22 during the bending process.
It is fixed by 54 at the optimum position before inductors 49, 50.
Reference numeral 55 is a curved pipe portion of the inner pipe 21, and 56 is a curved pipe portion of the outer pipe 22.

Also, FIG. 4 is an enlarged view showing the details of the curved pipe portion, in which 4
9'and 50 'are cooling water for giving rigidity so that the part that is pressed and bent in the high temperature plastic region will not be further deformed.
The inductors 49 and 59 are jetted from a cooling jacket which is machined around the entire circumference at an appropriate pitch. 49 'is inner pipe cooling jacket water and 50' is outer pipe cooling jacket water.

The bending process for manufacturing the double bent tube by the above apparatus will be described below.

First, the end of the double pipe shown in FIG. 1 on the flange 23 side is placed on the clamp jig 31, and is firmly fixed by the hydraulic cylinder 33, while the rear end of the inner pipe 21 is placed on the slide clamp 38. Then, the outer cylinder 22 is firmly fixed by the hydraulic cylinder 39, the rear end of the outer tube 22 is arranged on the clamp 40, and it is firmly fixed by the hydraulic cylinder 41, and the clearance between the inner tube 21 and the outer tube 22 is fixed. The guide ring 53 is fixed at an optimum position with respect to the guide bar 54, for example, a position that comes in front of the inductors 49 and 50 in order to hold the guide ring 53.

As described above, the double pipe is set in the pipe bending device, and high frequency current is passed from the transformers 47 and 48 to the inductors 49 and 50 through the leads 51 and 52, and the inner pipe 21 and the outer pipe 22 are connected. Inductor 49 and cooling water
When the tilt main body 37 is propelled while being heated and cooled by 49 ', the inductor 50 and the cooling water 50', the bending arm 32 pivots,
The inner pipe 21 and the outer pipe 22 are continuously bent with a predetermined radius.

Then, after the bending process is completed, the guide ring 53 is pulled out to remove the guide bar 54, and as described above, the flange 24 is attached to the end of the straight pipe portion on the rear side of the inner pipe 21 by welding, and the outer In order to fill the gap generated between the end of the straight pipe portion on the rear side of the pipe 22 and the flange 24, by disposing a short pipe member 25 in this portion and connecting them firmly and watertightly by welding, Flange
That is, 23, 24 double curved tubes are installed.

〔The invention's effect〕

The present invention is as described above, in the conventional method of manufacturing a double bent pipe, the material is composed of a large number, and they are continuous by welding to form a double bent pipe,
Although there are many welded portions and heating fluid such as water vapor easily leaks from the welded portions, which is often inconvenient, the method of the present invention significantly reduces the number of welded portions as compared with the above-described conventional method. , The risk of heating fluid leaking from the weld is extremely low, and therefore it is suitable as a method for manufacturing double curved pipes used in fine chemical plants, etc. Since it can be constructed only by adding a few devices, it is possible to manufacture and provide it at a relatively low cost, without fear of large scale.

[Brief description of drawings]

FIG. 1 is a front view of a section of a double tube formed as a pre-stage for manufacturing a double bent tube by the method of the present invention, and FIG. 2 is an example of a double bent tube manufactured by the method of the present invention. FIG. 3 is a plan view of an apparatus of the present invention for carrying out the method of the present invention, and FIG. 4 is an enlarged view of the curved pipe section in FIG.
FIG. 5 is a view showing an assembly welding structure of an inner pipe by a conventional method,
FIG. 6 is a view showing a welding structure in which an outer pipe is assembled outside the inner pipe of FIG. 21 …… inner tube, 22 …… outer tube, 23,24 …… flange, 25 ……
Short tube member, 31 …… Clamping jig, 32 …… Bending arm, 33 …… Hydraulic cylinder, 35 …… Main body frame, 36 …… Hydraulic cylinder, 37
...... Till body, 38 …… Sliding clamp, 39 …… Hydraulic cylinder, 40 …… Clamp for fixing outer tube, 41 …… Hydraulic cylinder, 42 …… Guide roller, 47,48 …… Transformer, 49,50 …
… Inductor, 53 …… Guide ring, 54 …… Guide bar, 55
...... Bent pipe part of inner pipe, 56 …… Bend pipe part of outer pipe

Claims (3)

[Claims] 1. An inner pipe and an outer pipe formed shorter than the inner pipe are combined in a double pipe shape with an appropriate gap therebetween, and the tips of the inner pipe and the outer pipe are flange-welded or other suitable. A double tube in which both tubes are fixed at regular intervals and combined into a unitary structure, and the inner tube of the double tube is from its inner side and the outer tube is also from its outer side, respectively, and simultaneously narrowed by high frequency induction heating. While heating in an annular shape, the tip of the outer pipe is clamped by a bending arm, and the rear ends of both pipes are clamped respectively, and an adjustable thrust force is applied to the rear ends of the both pipes to increase the temperature by the heating. A method for manufacturing a double bent pipe, characterized by continuously bending in a plastic region. 2. An inner pipe and an outer pipe formed shorter than the inner pipe are combined in a double pipe shape with an appropriate gap therebetween, and the tips of the inner pipe and the outer pipe are flange-welded or other suitable. A double tube in which both tubes are fixed at regular intervals and combined into a unitary structure, and the inner tube of the double tube is from its inner side and the outer tube is also from its outer side, respectively, and simultaneously narrowed by high frequency induction heating. The inner pipe or the inner pipe is heated while being annularly held, and the tip of the outer pipe is clamped by a bending arm, and the rear ends of the both pipes are respectively clamped, and an adjustable thrust is applied to the rear ends of the both pipes. While adjusting the length of the outer pipe or both pipes, continuously bend in a high temperature plastic region by the heating, after a predetermined bending work, attach a flange to the rear end of the inner pipe, In the gap created between the flange and One divided arrange short pipe member made the same tube diameter and the outer tube if coalescence, the manufacturing method of the double track pipe, characterized in that connected to the water-tight by welding. 3. A swingable bending arm for gripping the tips of an inner pipe and an outer pipe to be formed into a double curved pipe by a clamp, and a narrow width of the inner pipe from its inner side and an outer pipe from its outer side. And high-frequency induction heating means for heating the two tubes, and clamping means for holding the rear ends of both tubes and applying a thrust force from the rear, so that both tubes are continuously bent in the high temperature plastic region by the heating means. In the device described above, the bending arm for clamping the outer pipe of the double pipe in which the tips of the inner pipe and the outer pipe shorter than that are fixed by a flange or other appropriate means, and the rear end of the double pipe are separately clamped. Along with a clamp jig for applying a thrust force, and an induction heating means arranged inside the inner pipe and outside the outer pipe, the clamp jig is affected by thermal stress or other influences during the bending process. Occur Provided with a control device that appropriately controls thrust to alleviate strain and residual stress between the inner and outer pipes, and detachable between both pipes to keep the gap between the inner and outer pipes constant. An apparatus for manufacturing a double curved pipe, characterized by comprising a guide ring inserted into the.