JPS62144831A - Method and device for forming tube with multi-thread spiral fin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for forming integral helical external fins on evaporator tubes of various lengths.
More particularly, a plurality of fins are formed from a plurality of fin starting points, each helical fin being curved to form a subsurface channel having spaced apart holes therealong around each helical fin. The present invention relates to a method and apparatus for forming the same.

Tubes formed in accordance with the present invention are such that the fluid to be cooled is passed through the tube and the boiling liquid is brought into contact with the outer surface of the tube, thereby transferring heat to the boiling liquid from the fluid within the tube. Used in evaporator type heat exchangers.

Prior Art As disclosed in U.S. Pat. No. 4,425,696, an evaporator tube with enhanced heat transfer properties (an evaporator tube formed with subsurface channels opening small holes as described above) is provided with grooves. A mandrel with a 30 mm diameter is placed in a green tube and a tool arm carrying a tool gun is transferred onto the outer surface of the tube. The unformed tube is pressed against a mandrel and
This forms at least one internal rib on the inner surface of the tube. At the same time, a spiral external fin is formed on the outer surface of the tube by the tool arm carrying the tool gang. These helical outer fins are pressed down at a location radially outward of the inner rib, ie, at the location where the tube is pressed against the groove of the mandrel to form the rib. After the external fins are formed, a smooth roller-like disc carried by a tool arm is rolled onto the outer surface of the tube. The roller disc is configured to curve the tips of the outer fins only in areas not located radially outward of the inner ribs so as to bring them into contact with adjacent helical fins. The tips of the external fins in the depressed areas located radially outward of the internal ribs are also curved, but they do not contact the adjacent helical fins, thereby allowing the circumference of the tube and the subsurface channels of the tube to be curved. A small hole is formed to provide fluid communication between the two.

Furthermore, it is known that the fin forming process can be performed more quickly by forming the fins from a plurality of starting points, that is, by forming a plurality of sets of spiral fins. However, when the smooth roller-like discs of the aforementioned US patents are used in combination with the multi-start fin formation method, the fins are not properly curved by the roller-like discs and are crushed, thereby causing the subsurface channels to collapse. The cross-sectional area is reduced, resulting in a reduction in the heat transfer performance of the tube.

SUMMARY OF THE INVENTION One object of the present invention is to overcome the above-mentioned problems and drawbacks of the prior art and to provide an improved heat transfer performance of an evaporator tube manufactured by a multi-start fin forming method. It's about improving.

Another object of the present invention is to provide a multi-striped roller disc with a roller disc configured to collapse the fins and thus curve a plurality of sets of helical fins without reducing the cross-sectional area of the subsurface channel. To provide a tool gang.

These objectives are achieved by a novel method and apparatus for forming pores and subsurface channels in a tube having multiple sets of helical fins. According to the present invention, in a tube having fins manufactured by a multi-fin forming method, the fins are curved by a desired amount by a plurality of roller disks. The roller disc is mounted on the tool arbor and
Adjacent disks are separated from each other by spacers.

The roller disc has a generally sloped surface. The point of contact between the sloped surfaces of adjacent roller disks and the fins to be curved and the angle of inclination of the sloped surfaces of mutually adjacent roller disks are varied gradually to effect the desired curvature of the fins.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Since evaporator tubes with enhanced heat transfer properties have critical dimensions that must be precisely controlled to maintain good heat transfer performance, this invention is particularly suited to improved heat transfer properties. An example used for an evaporator tube will be described. Such enhanced heat transfer tubes are designed for use in evaporators of refrigeration systems in which the fluid to be cooled flows within the heat transfer tube and the refrigerant to be evaporated is placed in contact with the outer surface of the tube. . Typically, a plurality of heat transfer tubes are mounted in parallel, several tubes are connected to form one fluid circuit, and a plurality of such parallel fluid circuits are provided to form a tube bundle. Ru. Generally, all the tubes of the plurality of fluid circuits are housed within a shell and immersed in a refrigerant within the shell. The heat transfer capacity of an evaporator is determined primarily by the average heat transfer characteristics of the individual heat transfer tubes. The dimensions of the subsurface channels and of the pores formed in the surface of the tube are of particular importance. A multi-thread manufacturing method is preferred to produce a tube with further improved heat transfer properties. This is because this method allows for a faster process.

FIG. 1 is an illustration of a fin forming station for producing tubes with enhanced heat transfer properties for use in connection with the present invention. The fin forming station 10 includes an electronic control cabinet 12, a supply section 14, a multi-fin forming head section 16, and a discharge section 3.
2 and a quality control section 18. The electronic control cabinet 12 includes an operator console 22 having a programmable controller that performs logic operations, timing control, sequence control, and calculations to perform the fin forming process. The feed section 14 includes two generally axially parallel mandrels 24 (the rear mandrel lies in the same horizontal plane as the front mandrel and is therefore omitted in FIG. 1). I'm here. Typically, these mandrels have a plurality of support arms 2
6 and is driven by a piston device 28. Therefore, the operator must
4, and one mandrel, e.g. the front mandrel, is lowered to align the longitudinal axis 2 of the fin formation.
9 into the fin-forming head section 16 . The fin forming head section includes a plurality of forming roll assemblies. Preferably, three forming roll assemblies are used, mounted substantially parallel to each other and spaced 120 degrees apart. The axis of the forming roll assembly is
It is inclined at a small angle to the longitudinal axis of the fin formation so that a plurality of helical fins are formed on the surface of the tube as it is advanced through the fin formation head section. Each forming roll assembly includes a tool arm carrying a tool gang. The tool gang includes at least one group of fin-forming disks and a group of rollers that cooperate with the mandrel to form a tube with improved heat transfer in accordance with the present invention.

A first fin-forming disk on each tool gang contacts the blank tube in a plane perpendicular to the two longitudinal axes of the fin formation. Although each helical groove is sloped to form an external fin, their starting points are in the same transverse plane and are evenly spaced around the circumference of the tube. For example, in a fin forming machine with three tools,
Three independent external fins are formed, each fin having a starting point in the same transverse plane and spaced 120 degrees from each other. Therefore, one revolution of the tube, i.e. 36
Upon completion of a 0 degree rotation, three independent helical fins are formed, and three more helical fins are formed for each subsequent rotation. The tools A are rotatable in the same angular direction simultaneously and synchronously with each other, and the frictional engagement between the fin-forming disc and the tube causes the tube to rotate and advance. Once the material tube has been rendered heat transfer-enhanced over a desired length, the tube contacts a position switch (not shown) which is positioned at a radius away from the heat transfer-enhanced tube. Moving the three forming roll assemblies in an outward direction, ejector means 32 , such as ejector wheels, engage the heat transfer enhanced tube and send it to the quality control section 18 . Once the heat transfer enhanced tube is fully positioned within the quality control section 18, the front mandrel is retracted to its original position, the rear mandrel is lowered, and the process described above is repeated.

FIG. 2 shows the relationship between a tube whose heat transfer properties are being improved, a forming roll assembly spaced from the tube, and a mandrel inserted into the tube.

Although the preferred embodiment includes a plurality of forming roll assemblies, for example three forming roll assemblies spaced 120 degrees from each other, only one forming roll assembly is shown in FIG. 2 for clarity. ing. The tube 30 is loaded onto the mandrel 24 and moves from the left to the right in the figure. The mandrel 24 is of sufficient length to be supported on the inner surface of the tube 30 beneath one disk 54 and a set of rollers 56. A group of disks 54 carried on a tool arbor 52 are brought into contact with the tube 30 at a small angle to the longitudinal axis 29 of the fin formation. This small angle of inclination provides the force necessary to drive the tube 30 along its longitudinal axis by rotating the forming roll assembly. Fin-forming disk 54 displaces material in the wall of tube 30 to form a helical external fin while simultaneously moving tube 30 onto mandrel 24.
f1 of the mandrel 24 by pressing the wall of the tube against
31 , thereby forming internal ribs 33 . The displacement of the tube wall to form the internal rib 33 presses the helical external fin at the radially outward portion of the internal rib 33, causing the fin-forming disc 54 to press against the helical external fin. Roller 5 after forming
6 is rolled onto the outer surface of the tube 30, the roller disc gradually curves the tip of the fin and the internal rib 33
Only those helical fins that are not located radially outwardly of, and therefore are not pressed against, are brought into contact with adjacent helical fins, thereby forming subsurface channels. Portions of the helical outer fins located radially outwardly of the inner ribs are curved but do not contact adjacent helical fins, thereby forming spaced apertures along the subsurface channel.

FIG. 3 shows details of the construction of the group of rollers 56.

For example, in operation of the preferred embodiment having three forming roll assemblies, the group of rollers 56 includes a number of roller-like discs 58 with spacers 59 interposed between the discs. The roll-forming surface 57 of each roller-like disc 58 is inclined at an increasingly increasing angle with respect to a plane perpendicular to the longitudinal axis of the downstream disc in the direction of tube travel, so that the fins The tip 34 is gradually curved, which prevents the fin from collapsing and reducing the cross-sectional area of the subsurface channel 38. The spacer 59 prevents the already partially curved fins from impinging on the rear surface 55 of the roller-shaped disc 58 carried in the subsequent tool arbor. In one typical fin forming head section having three forming roll assemblies, the angled roll forming surface 57 of the first roller disc 58 first impinges on one fin, which then rotates. and passes along the plane of that spacer, thus not impinging on the roller-like disc. and then to a third forming roll assembly (a forming roll assembly spaced 240 degrees from the first forming roll assembly), and the inclined roll forming surface of the second roller-like disc of that assembly. Collision with 57. This process in which the fins are impinged by the roller-like disks of every other forming roll assembly continues until the tips 34 of the fins are curved to form the proper subsurface channels. Generally, the width of the spacer 59 is much smaller than the width of the roller disc 58, for example, the spacer is 0.003 inch smaller than the roller.
ch (0,076 mLa) so that the point of contact 60 between the inclined roll-forming surface 57 and the tip 34 of the fin is such that the point of contact 60 between the roll-forming surface 57 and the tip 34 of the fin is smaller than that in the subsequent roller-like disc 58 along the roll-forming surface 57 towards the back of that disc. move gradually. The fins are thus progressively curved so that the curved fins do not touch the back surface 55 of the previous adjacent disk 58. This is because the contact point 60 of the subsequent disc has already moved as described above, so that the distance between the contact point 60 and the back surface 55 of the previous disc remains constant.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. This will be clear to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is an illustration showing a multi-fin forming machine for manufacturing tubes with improved heat transfer according to the present invention. FIG. 2 is a side view showing one tool arbor of the fin forming machine shown in FIG. 1 with the tube that fits into the mandrel cut away. FIG. 3 is an enlarged partial cross-sectional view of one typical tube fin being curved by the roller disk structure of the present invention. DESCRIPTION OF SYMBOLS 10... Fin forming station, 12... Electronic control cabinet, 14... Supply section, 16...
・Fin forming head section, 18... Product Q Control-c Kunyong, 22... Operator console, 24
... mandrel, 26 ... support arm, 28 ... piston device, 29 ... longitudinal axis, 30 ... tube, 31 ... groove, 32 ... discharge section, 33 ...
・Internal rib. 34... Fin tip 1.54... Fin forming disk. 56... Roller, 57... Roll forming surface, 58...
・Roller discs, 5... Spacers, 60...
Contact Point Patent Applicant Carrier Corporation Agent Patent Attorney Akashi
Takeshi MasaFIG / FIG, 2

Claims (2)

[Claims] (1) A method for forming a tube having multiple spiral fins, which includes a step of supplying a material tube of a certain length, a step of supporting the outer surface of the material tube, and a step of providing a plurality of fin forming means. a step of engaging the material tube with the disk and rotating the material tube and the fin forming means relative to each other to form a multi-threaded helical upright fin; and having a spacer between each disk. and a plurality of roller disks, each successive disk having a roll forming surface with an inclined angle that gradually decreases when viewed in the direction of movement of the tube, so that the fins are gradually curved in the process of forming the subsurface channel. rolling means onto the helical upright fins, thereby forming a plurality of continuous subsurface channels having spaced apart perforations along the top. (2) An apparatus for forming a tube having multiple spiral fins, including means for supporting a material tube of a certain length, and a multiple curved fin forming a plurality of spiral fins on the outer surface of the tube. fin forming means, each curved fin forming means comprising a group of fin forming means for roll forming a plurality of helical upright fins on the outer surface of the material tube; and a plurality of curved fin forming means comprising a group of fin bending means forming a plurality of continuous subsurface channels having spaced apart perforations.