JPH0723046Y2 - Copper tube with internal groove - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a copper tube with an inner groove as a heat transfer tube used in a heat exchanger or the like.

[Prior Art] Conventionally, as this kind of inner surface grooved copper pipe, a strip-shaped copper plate having a groove formed on one surface thereof is formed into a tubular shape with its longitudinal direction as an axis and the groove is directed inward. Welded seams are known. A stepped recess is formed on the inner surface of the inner grooved copper tube along the joint.

When the above-mentioned inner surface grooved copper pipe is used for a heat exchanger, a heat radiation fin is usually connected to the outer periphery of the inner surface grooved copper pipe by pushing a pipe expanding jig into the inner surface grooved copper pipe. This is done by expanding the tube.

Further, according to the inner grooved copper pipe, since the recess is formed on the inner surface along the joint, even if the weld bead is raised at the joint, the weld bead is not scraped off by the pipe expanding jig. .

Therefore, it is possible to prevent a problem that the shavings of the bead remain in the copper tube with the inner groove and are mixed with the compressor or the like of the heat exchanger.

[Problems to be Solved by the Invention] However, in the above-mentioned inner surface grooved copper pipe, since a stepped concave portion is formed along the joint, the strength of this portion is small, and when the pipe is expanded by the pipe expanding jig. It may be damaged. Therefore, the wall thickness is increased in order to obtain sufficient strength of the recess, but then the wall thickness of the portion other than the recess must also be increased, resulting in an inner grooved copper tube having a large wall thickness as a whole. Will end up.

Therefore, even if the groove is provided in order to increase the heat transfer efficiency, there is a drawback that the heat transfer efficiency cannot be improved because the wall thickness is large.

The present invention has been made in view of the above circumstances and aims to improve the heat transfer efficiency in combination with the groove formed on the inner surface by reducing the strength of the recess as much as possible to reduce the overall thickness. The object is to provide a copper tube with an inner groove that can be manufactured.

[Means for Solving the Problems] In order to achieve the above object, the present invention forms a strip-shaped copper plate having a groove formed on one surface thereof in a tubular shape with the longitudinal direction as an axis and the groove facing inward. Then, in the copper tube with an inner surface groove formed by welding the seam, a curved concave portion that gradually deepens toward the seam is formed on the inner surface along the seam.

[Operation] In the present invention, the concave portion along the joint is formed in a curved shape so as to become gradually deeper toward the joint. For example, when a groove is formed by a rolling roll, the end of the rolling roll is formed. The recessed portion can be easily formed by the enlarged diameter portion formed in the above.

Further, since the concave portion is formed to have a curved surface and becomes gradually deeper, the concentration of stress generated in the concave portion is small, and the reduction in strength of the concave portion can be suppressed as much as possible.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in FIGS. 1 to 4, the inner grooved copper pipe 1 is
The strip-shaped copper plate 2 is formed in a tubular shape with the longitudinal direction as the axis and the groove 2a facing inward, and the joint 2b is connected by high frequency induction welding. Furthermore, the copper plate 2 has a groove.
A recess 2c is formed along the side edge on the side where 2a is formed, that is, along the joint 2b on the inner surface of the copper tube 1.

The groove 2a is formed in a V-shaped cross section or an inverted trapezoidal shape, and is formed in a direction that obliquely intersects the axis of the inner surface grooved copper tube 1.

The recess 2c is formed in a continuous curved surface so that the depth gradually increases toward the joint 2b, and the tangent direction of the joint 2b is formed parallel to the tangential direction of the outer peripheral surface.

In order to manufacture the inner surface grooved copper pipe 1 configured as described above, first, the grooves 2a and the recesses 2c are formed in the copper plate by a rolling roll (not shown). Thereby, the copper plate 2 shown in FIG. 4 is formed. However, the rolling roll has grooves on its outer peripheral surface.
A ridge for molding 2a is formed, and an enlarged diameter portion for molding the recess 2c is formed at the end in the axial direction. Then, the copper plate 2 is formed into a tubular shape with its groove 2a facing inward, and the seam 2b is welded by a high frequency induction welding method. At this time,
The weld beads 3 are raised on the inner surface side and the outer surface side. However, the weld bead 3 protruding to the outer surface side is removed by cutting or the like.

Then, in order to connect the radiating fins to the inner surface grooved copper tube 1,
A shell-shaped pipe expanding jig (not shown) is pushed into the inner grooved copper pipe 1 to expand the inner grooved copper pipe 1. At this time, since the weld bead 3 protruding to the inner surface is in the recess 2c, it is not scraped off by the pipe expanding jig.

Therefore, according to the inner surface grooved copper pipe 1 configured as described above, since the welding bead 3 is not scraped off by the pipe expanding jig, shavings of the welding bead 3 are generated in the inner surface grooved copper pipe 1 It doesn't stay inside. Therefore, it is possible to prevent the shavings from being caught in the compressor or the like of the heat exchanger and being damaged.

Further, since the recess 2c is formed by a continuous curved surface and the tangent directions of the inner and outer surfaces at the joint 2b are formed parallel to each other, the thickness of the recess 2c changes continuously and smoothly. Become. Therefore, since the stress concentration in the recess 2c can be relaxed, the thickness of the recess 2c can be reduced by an amount commensurate with the degree of reduction in the stress concentration, whereby the entire structure can be formed thin.

Therefore, the heat transfer efficiency of the inner surface grooved copper tube 1 can be improved in combination with the groove 2a formed on the inner surface.

Further, since the recess 2c is formed so as to become gradually deeper toward the joint 2b, the recess 2c can be easily formed by the enlarged diameter portion formed at the end of the rolling roll.
Moreover, when the groove 2a is formed obliquely with respect to the axis of the copper plate 2, the force applied to the groove 2a causes the rolling direction of the copper plate 2 to gradually shift from the regular feeding direction. However, in this case, since the concave portion 2c can be guided by the expanded diameter portion of the rolling roll, the copper plate 2 can be held straight in the regular feeding direction.

In the above embodiment, the recess 2c was formed into a curved surface when the copper plate 2 was formed, but this recess may be formed into an inclined flat surface when the copper plate 2 is formed. . This is because when the copper plate is formed into a tubular shape, the flat portion is also curved into a curved surface.

[Effects of the Invention] As described above, according to the present invention, a strip-shaped copper plate having a groove formed on one surface thereof is formed in a tubular shape with the longitudinal direction as an axis and the groove is directed inward, and the joint is formed. In the copper tube with internal groove formed by welding, the inner surface along the joint is formed with a curved concave portion that gradually becomes deeper toward the joint. Can be avoided.
Therefore, the stress concentration in the recess can be suppressed as small as possible, and the decrease in strength in the recess can be suppressed as small as possible.

Therefore, as much as the reduction in strength can be suppressed,
The thickness of the recess can be reduced, and thus the entire thickness can be reduced. Therefore, the heat transfer efficiency can be improved in combination with the groove formed on the inner surface.

[Brief description of drawings]

1 to 4 are views showing an embodiment of the present invention, in which FIG. 1 is a perspective view of an inner grooved copper pipe, and FIG. 2 is a sectional view showing a recess of the inner grooved copper pipe. 3 is a perspective view of a copper tube with an inner groove before welding, and FIG. 4 is a perspective view of a copper plate. 2 ... Copper plate, 2b ... Seam, 2c ... Recess.

Claims (1)

[Scope of utility model registration request] 1. An inner surface grooved copper pipe obtained by forming a strip-shaped copper plate having a groove formed on one side thereof into a tubular shape with the longitudinal direction as an axis and inwardly forming the groove, and joining the joints. The inner surface grooved copper pipe is characterized in that a curved surface-shaped concave portion that gradually becomes deeper toward the seam is formed on the inner surface along the seam.