MANUFACTURING METHOD FOR PIPE STRUCTURE

A manufacturing method for a pipe structure includes a pipe bending step for implementing for a plurality of times a bending process of bending a part of a straight pipe by wrapping the part around a peripheral surface of a rolling block to form a plurality of bend portions in intermediate locations along a longitudinal direction of the pipe. When a final bending process is implemented during the pipe bending step, a position of a rear end portion of the pipe is determined, and relative positions of the pipe and the rolling block in a predetermined y direction are controlled on the basis of the position of the rear end portion so that after the bending process, a y-direction position of the rear end portion is aligned with a y-direction position of the front end portion. According to this configuration, complicated operations such as cutting the respective end portions of the pipe after bending the pipe can be eliminated, and a pipe structure such as a meandering pipe body in which the positions of the respective end portions are aligned can be manufactured appropriately and with favorable productivity.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method for manufacturing a pipe structure having a meandering shape, a spiral shape, or the like, for example, which is used as a constituent element of a heat exchanger or the like.

Description of the Related Art

A meandering pipe body A such as that shown inFIG. 1, for example, is available as a pipe structure used as a heat transfer pipe of a heat exchanger. The meandering pipe body A is constructed by forming a stainless-steel pipe1in a meandering shape, and includes a plurality of bend portions10. Regions11A,11B near respective end portions of the pipe1are separated from each other in an x direction and extend in a y direction that intersects the x direction.

A method shown inFIG. 12, for example, is available as a method for manufacturing the meandering pipe body A. This manufacturing method includes a pipe manufacturing and press-cutting step S1, a pipe bending step S2, and a cutting and deburring step S3.

Here, the pipe manufacturing and press-cutting step S1, as shown inFIG. 13A, is a step for manufacturing a long, straight, stainless-steel pipe1B and then cutting the pipe1B into the pipe1of an appropriate length by pressing.

The pipe bending step S2, as shown inFIG. 13B, is a step for implementing a bending process a plurality of times so as to form the plurality of bend portions10in intermediate locations along the longitudinal direction of the pipe1. The bending process is performed by, for example, wrapping a part of the pipe1around a peripheral surface of a rolling block of a pipe bender and pressing the part of the pipe1against the peripheral surface. Deformed portions18that are flattened by the cutting performed during the aforesaid pressing process exist on respective longitudinal direction end portions11a,11bof the pipe1.

The cutting and deburring step S3, as shown inFIG. 13C, is a step for cutting the respective end portions11a,11bof the pipe1and deburring the cut locations. Cutting is performed to remove the deformed portions18and align y-direction positions of the respective end portions11a,11b. When the plurality of bending processes are performed on the pipe1, an error (variation) occurs in the position of each bend portion10, leading to a cumulative error in the pipe1as a whole, and as a result, the y-direction positions of the respective end portions11a,11bare likely to be misaligned such that positional deviation of a dimension L1occurs therebetween. By performing the cutting described above, however, this positional deviation is eliminated. As will be described below with reference toFIGS. 2A to 2C and 3, when the meandering pipe body A is used as a heat transfer pipe of a heat exchanger HE, for example, it is desirable for the y-direction positions of the respective end portions11a,11bto be aligned.

As described below, there remains room for improvement in the prior art described above.

In the prior art described above, the respective end portions11a,11bof the pipe1are cut after completing the bending processes on the pipe1, and therefore the cutting operation is complicated. As a result, the productivity of the meandering pipe body A is poor, and the manufacturing cost thereof is high. Hence, in these respects, there remains room for improvement.

In contrast to the above description, as shown inFIG. 14, for example, a pipe body in which the deformed portions18do not exist on the respective end portions11a,11bmay be used as the pipe1. However, when such a means is merely employed, the y-direction positions of the respective end portions11a,11bdeviate by a certain dimension L2. Likewise in this case, therefore, it is necessary to perform a cutting step to align the positions of the respective end portions11a,11b. As a result, the problem described above remains unsolved.

CITATION LIST

SUMMARY OF THE INVENTION

An object of the present invention is to provide a manufacturing method for a pipe structure with which complicated processes such as cutting respective end portions of a pipe after bending the pipe can be eliminated, whereby a pipe structure such as a meandering pipe body in which the positions of the respective end portions are aligned can be manufactured appropriately and with favorable productivity.

To achieve the object described above, the present invention teaches the following technical means.

A manufacturing method for a pipe structure provided by the present invention includes a pipe bending step for implementing for a plurality of times a bending process of bending a part of a straight pipe by wrapping the part around a peripheral surface of a rolling block in order to form a plurality of bend portions in intermediate locations along a longitudinal direction of the pipe, a region near a front end portion on a bend start side of the pipe and a region near a rear end portion on a bend end side being separated from each other in a predetermined x direction and extending in a y direction that intersects the x direction, wherein, when a final bending process is implemented during the pipe bending step, a position of the rear end portion of the pipe is determined, and relative y-direction positions of the pipe and the rolling block are controlled on the basis of the position of the rear end portion so that after the final bending process, a y-direction position of the rear end portion is aligned with a y-direction position of the front end portion.

The pipe structure can be set as a meandering pipe body or a spiral pipe body.

Preferably, detecting means for detecting the rear end portion of the pipe is used in an operation for controlling the relative y-direction positions of the pipe and the rolling block on the basis of the position of the rear end portion, and by using the detecting means, the pipe is positioned so that the rear end portion of the pipe is disposed a predetermined dimension away from the rolling block in the y direction.

Preferably, the predetermined dimension is a y-direction dimension from the rolling block to the front end portion of the pipe in a state where the pipe and the rolling block have been positioned to implement a first bending process on the pipe.

Preferably, the manufacturing method for a pipe structure according to the present invention includes a step for determining a projection dimension in the y direction from the rolling block to the front end portion of the pipe when positioning the pipe and the rolling block to implement the final bending process, wherein the predetermined dimension is set at a value corresponding to the projection dimension.

Preferably, a pipe on which respective longitudinal direction end portions have been laser-cut is used as the straight pipe.

Other features and advantages of the present invention will become more apparent from the embodiment of the invention that is described below with reference to the figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will be described specifically below with reference to the figures.

The manufacturing subject of the manufacturing method for a pipe structure according to this embodiment, similarly to the prior art described above, is the meandering pipe body A shown inFIG. 1. Accordingly, identical or similar elements to the prior art have been allocated identical reference symbols to the prior art.

First, the meandering pipe body A will be described.

As described above, the meandering pipe body A is constructed by forming the stainless-steel pipe1, for example, in a meandering shape, and includes the plurality of bend portions10, each of which has a bend angle of 180 degrees, and a plurality of straight portions11connected via the plurality of bend portions10. The regions11A,11B near the respective end portions of the pipe1are separated from each other in the x direction, which is a horizontal width direction inFIG. 1, and extend in the y direction. The x and y directions intersect each other.

The heat exchanger HE shown inFIGS. 2A to 2Cis constructed using the plurality of meandering pipe bodies A. More specifically, in the heat exchanger HE, the plurality of meandering pipe bodies A are housed in a case7so as to be stacked in an up-down height direction and so as to deviate from each other positionally in a left-right horizontal width direction. The respective end portions11a,11bof each meandering pipe body A are drawn out to the exterior of the case7, and water inlet and hot-water outlet headers8a,8bare attached thereto. Water to be heated and hot water flow into and out of the meandering pipe body A through the headers8a,8b. An intake port70and an exhaust port71for heating gas such as combustion gas generated by a burner, not shown in the figures, are provided in the case7. The meandering pipe bodies A function as heat transfer pipes for recovering heat from the heating gas. The water to be heated is heated while flowing through the meandering pipe bodies A, and as a result, warm water for use in a hot water supply is generated.

When manufacturing the heat exchanger HE described above, the headers8a,8bare attached to the respective end portions11a,11bof each meandering pipe body A, as shown inFIG. 3. In this case, it is a requirement to align not only x-direction positions of the respective end portions11a,11b, but also the y-direction positions thereof. When the y-direction positions of the respective end portions11a,11bdeviate from each other, unevenness occurs in the manner in which the water to be heated and the hot water flow through the headers8a,8b. Moreover, when the positional deviation in the y direction is large, attachment of the headers8a,8bmay be impeded. The manufacturing method for a pipe structure according to this embodiment can respond to this requirement. The content thereof will be described below.

In the manufacturing method for a pipe structure (the meandering pipe body A) according to this embodiment, as shown inFIG. 4, a pipe manufacturing and press-cutting step Sa, a laser-cutting step Sb, and a pipe bending step Sc are performed in succession.

The pipe manufacturing and press-cutting step Sa, as shown inFIG. 5A, is a step for manufacturing a long, straight pipe1A. The pipe1A is formed by press-cutting respective end portions thereof. Further, manufacture (pipe manufacture) of the pipe to be press-cut is realized by rounding a flat plate-shaped stainless-steel member, for example, into a round pipe shape and joining a mating portion thereof by laser welding or the like.

The laser-cutting step Sb, as shown inFIG. 5A, is a step for acquiring the pipe1of a predetermined length La, shown inFIG. 5B, by laser-cutting the pipe1A described above. By performing laser-cutting, deformed portions such as flattened portions are not generated on the respective end portions11a,11bof the pipe1. Moreover, burrs are unlikely to occur. Hence, there is no need to perform a cutting step for removing the flattened portions or deburring. The length La of the pipe1is identical to an overall length dimension (a flow passage length) of the finally acquired meandering pipe body A.

The pipe bending step Sc is a step for implementing a bending process on the pipe1a plurality of times so as to form the pipe1in a meandering shape as a whole. A pipe bender PB such as that shown inFIGS. 6A and 6B, for example, is used to bend the pipe1.

The basic configuration of the pipe bender PB is known from the prior art (see Japanese Patent Application Publication No. 2019-126830 and Japanese Patent Application Publication No. 2012-135797, for example), and includes a rolling block2, a pressure die3, and a clamping die4. The pipe bender PB also includes a pipe chuck5and a position sensor6.

The rolling block2is capable of rotating horizontally about a shaft portion20, and a pipe insertion recess21is provided in an outer peripheral surface thereof so that a part of the outer peripheral surface of the pipe1can be inserted therein. The pipe insertion recess21includes a curved portion21acurved into an arc shape over an angle range of 180 degrees, and rectilinear portions21b,21cconnected to respective ends of the curved portion21a. A plurality of recessed groove portions22are provided at appropriate intervals in the curved portion21a. When the pipe1is bent, the recessed groove portions22serve as sites for facilitating compressive deformation of an inside region of the bend portion10.

The pressure die3is a block-shaped member having a pipe insertion recess31formed continuously in a side face thereof, and is capable of reciprocating in the x direction and the y direction when positioned beside the rolling block2. When the rolling block2is rotated, the pressure die3presses the pipe1on the opposite side to the rolling block2, and as a result, bending deformation can be applied to the pipe1.

The clamping die4is a site for clamping the pipe1together with the rolling block2so as to exert a pulling action on the pipe1, and a pipe insertion recess41is provided in a side face of the clamping die4. By rotating the clamping die4together with the rolling block2in the direction of an arrow Na inFIG. 6Aabout the shaft portion20, a part of the pipe1can be bent so as to wrap around the inner surface of the curved portion21aof the rolling block2, as shown inFIG. 7.

InFIG. 6A, the pipe chuck5is free to clamp and unclamp the pipe1, and by advancing toward the rolling block2side while clamping the pipe1, the pipe chuck5can perform an action for feeding the pipe1toward the rolling block2side. Further, the pipe chuck5can rotate the pipe1by rotating about the axial center of the pipe1(rotating in the direction of an arrow Nb inFIG. 6A) while clamping the pipe1.

The position sensor6is a light-reflecting optical sensor having a light-emitting element and a light-receiving element, for example, and is capable of detecting a position of an edge of the rear end portion11bof the pipe1. In this embodiment, when the edge of the rear end portion11breaches a front surface of the position sensor6while the pipe1is fed toward the rolling block2side, the edge can be detected. The position sensor6corresponds to an example of the “detecting means for detecting the rear end portion” of the present invention. A light-transmitting optical sensor or a sensor other than an optical sensor may be used as the position sensor6instead of a light-reflecting optical sensor.

The pipe bending step Sc is performed by implementing processes such as those shown inFIGS. 8A to 8G. These processes will be described below.

First, as shown inFIG. 8A, the pipe1is set so as to be clamped between the rolling block2and the pressure die3and clamping die4. At this time, a y-direction dimension Lb between (an edge of) the front end portion11aof the pipe1and the rolling block2is set at a predetermined dimension. In this state, as shown inFIG. 8B, a first bending process is performed by rotating the clamping die4and the rolling block2in the direction of an arrow Na, and as a result, the bend portion10is formed.

Next, as shown inFIG. 8C, the orientation of the pipe1is changed by rotating the pipe chuck5in the direction of an arrow Nc, and the pipe chuck5is caused to advance toward the rolling block2side. The clamping die4and the rolling block2are returned to the original positions thereof so as to avoid interference with the pipe1. In so doing, as shown inFIG. 8D, preparation for a second bending process can be implemented. Next, as shown inFIG. 8E, the second bending process is performed by again rotating the clamping die4and the rolling block2in the direction of the arrow Na, and as a result, the second bend portion10is formed.

As is evident from the first and second bending processes, in the pipe bending step Sc, an operation for implementing a bending process on the pipe1by rotating the clamping die4and the rolling block2after changing the orientation of the pipe1and feeding the pipe1toward the rolling block2side is implemented repeatedly. In so doing, a meandering pipe body A′ such as that shown inFIG. 8Fis manufactured. The meandering pipe body A′ is in a state prior to implementation of a final bending process.

When the final bending process is performed on the pipe1, control for positioning the pipe1is implemented in advance so that the edge of the rear end portion11bof the pipe1is positioned on the front surface of the position sensor6and detected by the position sensor6. In so doing, a dimension Lc from the edge of the rear end portion11bto the center of the rolling block2is set accurately at a predetermined dimension. The dimension Lc is identical to the dimension Lb from the edge of the front end portion11ato the center of the rolling block2in the initial set state shown inFIG. 8A, for example.

In the set state described above, as shown inFIG. 8G, the final bending process is performed by rotating the clamping die4and the rolling block2. As a result, the meandering pipe body A shown inFIG. 1is acquired. However, since relative positioning in the y direction has been carried out between (the edge of the rear end portion11bof) the pipe1shown inFIG. 8Fand the rolling block2, the y-direction positions of the respective end portions11a,11b(the front end portion11aand the rear end portion11b) of the meandering pipe body A are aligned.

According to the manufacturing method described above, a state in which the final bend portion10(10b) is positioned lower than the other, intermediate, bend portions10by a certain dimension Ld, as shown inFIG. 9A, for example, or a state in which the final bend portion10(10b) is positioned higher than the other, intermediate, bend portions10by a certain dimension Le, as shown inFIG. 9B, for example, may occur. However, the y-direction positions of the respective end portions11a,11bare aligned appropriately, and therefore the acquired meandering pipe body A can be used favorably to manufacture the heat exchanger HE shown inFIGS. 2A to 2C. When the y-direction positions of the respective end portions11a,11bare misaligned, it is necessary to cut the respective end portions11a,11bin order to adjust the lengths thereof as means for eliminating the misalignment, but according to this embodiment, this is not necessary. Hence, the productivity of the heat exchanger HE can be improved, and the manufacturing cost thereof can be reduced.

FIGS. 10A and 10Bshow a spiral pipe body Aa serving as another example of the pipe structure according to the present invention.

In the spiral pipe body Aa, a plurality of bend portions10with a bend angle of 90 degrees are formed in intermediate locations along the longitudinal direction of the pipe1so that the pipe1is formed in a substantially rectangular spiral shape when seen from the front. The regions11A,11B near the respective end portions of the spiral pipe body Aa are separated from each other in the x direction and extend in the y direction. The spiral pipe body Aa can also be used as a heat transfer pipe of a heat exchanger.

The spiral pipe body Aa can be manufactured by performing a bending process such as that shown inFIGS. 11A to 11F, for example.FIGS. 11A to 11Fare schematic views showing the positional relationship between the pipe1and the rolling block2, and the other constituent elements of the pipe bender have been omitted.

First, in a state where the pipe1is lined up against the rolling block2, as shown inFIG. 11A, the pipe1is bent by 90 degrees in the direction of an arrow Nd, as shown inFIG. 11B. Next, as shown inFIG. 11C, the pipe1is fed by a predetermined dimension in the direction of an arrow Ne, whereupon the pipe1is again bent by 90 degrees, as shown inFIG. 11D. By repeating this process, a spiral pipe body Aa′ is acquired in a form such as that shown inFIG. 11E.

The spiral pipe body Aa′ is in a state immediately before the final bending process, and before implementing the final bending process thereon, the edge of the rear end portion11bof the pipe1is detected by the position sensor6, whereupon the position of the pipe1is controlled so that a dimension Lc′ from the edge of the rear end portion11bto the center of the rolling block2matches a dimension Lb′, shown inFIG. 11A, for example, from the edge of the front end portion11ato the center of the rolling block2. Next, as shown inFIG. 11F, the final bending process is implemented on the pipe1such that the y-direction positions of the front end portion11aand the rear end portion11bof the pipe1are aligned.

The present invention is not limited to the content of the embodiment described above. The specific configurations of the respective operation steps of the manufacturing method for a pipe structure according to the present invention may be variously modified within the intended scope of the present invention.

In the embodiment described above, as means for aligning the y-direction position of the rear end portion11bof the pipe1with the y-direction position of the front end portion11aafter performing the final bending process on the pipe1, the dimension Lc shown inFIG. 8F, for example, is made identical to the dimension Lb ofFIG. 8A, but the present invention is not limited thereto. In the present invention, it is also possible to employ means for controlling the relative positions of the pipe1and the rolling block2by detecting the position of the front end portion11ain the state shown inFIG. 8F, for example, using an appropriate sensor (for example, a sensor6A indicated by virtual lines) so as to determine a projection dimension Lf in the y direction from the rolling block2to the front end portion11a, and making the dimension Lc identical to a value corresponding to the projection dimension Lf (for example, a value acquired by adding the arc length of the bend portion10to the projection dimension Lf).

There are no limitations on the specific number and bend angle of the bend portions formed in the pipe. In the embodiment described above, the bend angle of the bend portions10formed in the meandering pipe body A is 180 degrees, and the bend angle of the bend portions10formed in the spiral pipe body Aa is 90 degrees, but other bend angles can be used. There are also no limitations on the specific bend radius of the pipe, the size and material of the pipe to be bent, and so on. An elliptical pipe may be used instead of a perfectly circular round pipe.

The pipe structure manufactured by the present invention is suitable for use as a heat transfer pipe of a heat exchanger, but can also be used in other applications. The pipe structure is not limited to a meandering pipe body or a spiral pipe body.