JP2007111718A - Extrusion die for multi-hole flat tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extrusion die for a multi-hole flat tube capable of prolonging the lifetime of the die by reducing the breakage of end forming projecting parts at both ends of a mandrel which is most likely broken without impairing the extrusion productivity. <P>SOLUTION: The die 1 for extruding a flat tube in which a plurality of holes are partitioned by a plurality of inner columns arranged inside parallel to each other comprises a female die 3 having an opening part 31 for forming an outer shape of the flat tube, and a male die 4 which is combined with the female die 3 and has a mandrel 2 arranged within the opening part 31 to form the inner columns and holes. The mandrel 2 has a plurality of forming projecting parts (21, 22, etc.) corresponding to the holes, and has a plurality of slits (26, 27, etc.) corresponding to the inner columns. A shoulder part 23 projecting outwardly in the width direction at a root side of the end forming projecting parts 21 is formed on the end forming projecting parts 21 located on both ends in the width direction out of the forming projecting parts, and the width W2 at the shoulder part 23 is set to be ≥ 2 times the width W1 at its fore-end. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an extrusion die for extruding a multi-hole flat tube used for, for example, a heat exchange tube for a condenser of an air conditioner.

  Conventionally, as an extrusion die 101 for extruding a multi-hole flat tube 9 as shown in FIG. 2, a combination of a female die 103 having an opening 131 and a male die 104 having a mandrel 102 as shown in FIG. It has been known. However, since the multi-hole flat tube 9 manufactured using such an extrusion die is required to be downsized and super-multi-hole as performance of the heat exchanger increases, It is getting thinner. In addition, while crying out for a drastic cost reduction, extrusion production at ultra-high speed is required to improve productivity, and the load on the mandrel 102 is further increased. In particular, the end molding protrusions located at both ends of the mandrel 102 There is a problem that 121 is easily broken and has a short life.

The cause of the breakage of the end molding convex 121 is that the inner column 96 is thinner than the outer peripheral wall 98 of the multi-hole flat tube 9, so that a pressure difference occurs between the left and right of the end molding convex 121. It is thought that this is because stress in the inner direction is generated in the molding convex portion 121. As a measure for improving the life of the end molding convex portion 121, a method of reducing the pressure difference by making the width of the slit 126 corresponding to the outermost inner pillar larger than the width of the other inner slit 125 (for example, Patent Document 1) or a method of increasing the rigidity of the end molding convex portion 121 by making the depth of the slit 126 corresponding to the outermost inner pillar shallower than the depth of the other inner slit 125 (for example, Patent Reference 2) is disclosed. In addition, a method for preventing a mandrel from cracking or missing by fitting the tip of the mandrel into a holding frame (for example, see Patent Document 3) is also disclosed.
Japanese Patent No. 3113100 Japanese Patent No. 3695156 JP 2004-306124 A

  However, in the case where it is required to manufacture a multi-hole flat tube 9 having a shape that is symmetrical in the vertical and horizontal directions and has a uniform hole interval as shown in FIG. 2, it is possible to increase the width of the slit 126 at the end and the formed convex portion 121. It was difficult. Further, if the depth of the slit 126 at the end is made shallower, the material flow becomes worse and the moldability is affected.

  Therefore, the present invention has been made against the background of the above circumstances, reducing the breakage of the end projections at both ends of the mandrel that is most likely to break without impairing the extrusion productivity, and improving the mold life. It is a technical object to provide an extruded die for a multi-hole flat tube.

  When extrusion molding is performed with an extrusion die 101 as shown in FIG. 100, it is assumed that if the shear stress due to the pressure difference between the outer side and the inner side of the end molding convex part 121 exceeds the mold strength, as shown in the schematic diagram of FIG. Is done. When the fracture surface of the edge-shaped convex part 121 that was actually broken was enlarged and examined, it was observed that the fracture was from the outside toward the inside. Further, when a pseudo model was created and experimented, it was found that a large amount of material flowing into the outside of the end molding convex portion 121 was flowing inward.

  Therefore, the present inventors provided a shoulder portion 23 that protrudes like a shoulder from the side as shown in the schematic diagram shown in FIG. I found out that it reduces the amount of inflow. This shoulder portion 23 increases the resistance of the material flowing from the outside of the end molding convex portion 21, reduces the pressure from the outside, reduces the pressure difference between the left and right of the end molding convex portion 21, and reduces the mold life. It is possible to improve.

  That is, in order to solve the above technical problem, the present invention has an outer peripheral wall 98 that forms a flat outer shape as described in claim 1 and is arranged in parallel in the width direction inside the outer peripheral wall 98. In the die 1 for extruding a flat tube 9 in which a plurality of holes (91, 92,...) Are partitioned by a plurality of inner pillars (96, 97,...) Arranged outside, the outside of the flat tube 9 A female die 3 having an opening 31 for forming a shape, and a combination with the female die 3 and an inner column (96, 97,...) And a hole (91, 92,...) Disposed in the opening 31. .) And a male die 4 having a mandrel 2 for molding, and the mandrel 2 has a plurality of molding convex portions (21, 22,...) Corresponding to the holes (91, 92,...). , A plurality of slits (26, corresponding to the inner pillars (96, 97, ...)) 7), and the end forming convex portion 21 located at both ends in the width direction of the forming convex portion is formed with a shoulder portion 23 protruding outward in the width direction on the base side, The width W2 of the end molding convex portion 21 at the shoulder 23 is set to be at least twice the width W1 of the end molding convex portion 21 at the tip at least at a position 1/2 the depth of the slit 26 from the tip. This is an extrusion die for a multi-hole flat tube.

  Preferably, as described in claim 2, on the front side in the extrusion direction of the shoulder portion 23, a surface 24 that is opposed to the pressure receiving surface 32 of the female die 3 and is perpendicular to the extrusion direction is configured. In this way, by making the front side of the shoulder portion 23 a vertical surface 24, the material that is parallel to the pressure receiving surface 32 and flows in the direction of the extrusion axis is bent in the vertical direction, so that the resistance of the material flow As a result, the force acting on the end molding convex portion 21 can be further reduced.

  According to the present invention, a flat tube having an outer peripheral wall forming a flat outer shape and having a plurality of holes partitioned by a plurality of inner pillars arranged in parallel in the width direction inside the outer peripheral wall is extruded. In the die to be molded, it becomes possible to reduce the breakage by suppressing the flow of the material from the outside of the end molding convex portion, and the die life can be improved.

  Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional view of an extrusion die 1 showing an embodiment of the present invention. As shown in FIG. 1, the extrusion die 1 includes a female die 3 having an opening 31 for shaping the outer shape of the flat tube 9 and a male die 4 having a mandrel 2. It is configured in combination. The multi-hole flat tube 9 in this embodiment is used for a heat exchange tube for a condenser of an air conditioner.

  As shown in FIG. 2, the multi-hole flat tube 9 has an outer peripheral wall 98 formed in a flat outer shape. Inside the outer peripheral wall 98, a plurality of inner pillars (96, 97,...) Are arranged in parallel in the width direction (left-right direction in FIG. 2). A plurality of holes (91, 92,...) Are partitioned by a plurality of inner pillars (96, 97,...). In the present embodiment, the plurality of inner pillars (96, 97,...) Are all set to the same thickness, and are thinner than the thickness of the outer peripheral wall 98. A plurality of inner holes (92,...) Other than the holes 91 at both ends are set to have the same width (same shape). The flat tube 9 has a vertically and horizontally symmetrical cross-sectional shape, and both ends are convex outward, so that the holes 91 at both ends are different from the inner holes 92. Specifically, the thickness of the inner pillar (96, 97,...) And the width of the inner hole 92 are each specifically a minute shape of 1 mm or less.

  The mandrel 2 is disposed in the opening 31 of the female die 3 and is configured to mold the inner pillars (96, 97,...) And holes (91, 92,...) Of the flat tube 9. , And having a plurality of forming convex portions (21, 22,...) Corresponding to the holes (91, 92,...) Of the flat tube 9 and corresponding to the inner pillars (96, 97,...). A plurality of slits (26, 27,...) Are provided. The depths D1 of the slits (26, 27,...) Are all set to the same depth.

  The end forming convex portions 21 positioned at both ends in the width direction of the flat tube 9 are formed with shoulder portions 23 protruding outward in the width direction on the root side. A surface 24 perpendicular to the extrusion direction is formed on the front side of the shoulder portion 23 in the extrusion direction (upper side in FIG. 1). The surface 24 faces the pressure receiving surface 32 of the female die 3, and the surface 24 and the pressure receiving surface 32 are parallel to each other. The connection part (corner part) of the surface 24 and the end molding convex part 21 is formed in a smooth curved surface, and the depth (extrusion axial direction distance) D2 from the tip of the end molding convex part 21 to the surface 24 is The slit depth D1 is set to be half or less. In the present embodiment, this D2 is 2/5 of the slit depth D1.

  The width W2 on the base side of the end molding convex portion 21 is set to be twice or more the width W1 at the tip. Preferably, it is 3 times or more, and further 5 times or more, and the width W2 of this embodiment is 5 times the width W1. That is, the width W2 of the end molding convex portion 21 at the shoulder 23 is set to be at least twice the width W1 of the end molding convex portion 21 at the tip at least at a position 1/2 the slit depth D1 from the tip. It is. However, if the width W2 becomes too large, it becomes difficult for the material to flow in, so the upper limit of the width W2 is 10 times the width W1.

  When extrusion is performed using the extrusion die 1 configured as described above, an aluminum alloy billet heated to a hot state is press-fitted from the back of the mandrel 2, and aluminum material flows from the periphery of the mandrel 2, The gap between the opening 31 of the mold 3 and the molding convex portions (21, 22,...) And the slits (26, 27,...) Are filled with aluminum material and sequentially pushed out. Will be formed.

  As shown in the schematic diagram of FIG. 3, the aluminum material flowing into the outer side of the end molding convex portion 21 becomes a resistance of the flow by the shoulder portion 23, and the flow of the material is suppressed. As a result, the difference between the inner direction force generated from the material flowing in the gap between the end molding convex portion 21 and the opening 31 and the outer direction force generated from the material flowing into the slit 26 is reduced. Breakage of the molding convex portion 21 is reduced. Therefore, the mold life can be greatly improved.

  Further, since the front side of the shoulder portion 23 is a surface 24 perpendicular to the extrusion axis direction, the material flowing into the outside of the end molding convex portion 21 is bent by 90 ° from the extrusion direction and flows. Resistance to the inner side of the end molding convex portion 21 can be suppressed.

It is sectional drawing which showed one Embodiment of this invention. It is sectional drawing of a multi-hole flat tube. It is a schematic diagram explaining one Embodiment of this invention. It is sectional drawing which showed the extrusion die of the prior art example. It is a schematic diagram explaining the extrusion die of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extrusion die 2 Mandrel 21 End molding convex part 22 Molding convex part 23 Shoulder part 24 Surface 26, 27 Slit 3 Female type 31 Opening part 32 Pressure receiving surface 4 Male type 9 Multi-hole flat tube (flat tube)
91, 92 Hole 96, 97 Inner column 98 Outer peripheral wall W1 Width at the tip of the end molding convex portion W2 Width at the base of the end molding convex portion D1 Slit depth D2 From the tip of the end molding convex portion to the front surface of the shoulder portion Depth of

Claims (2)

In a die that has an outer peripheral wall that forms a flat outer shape and extrudes a flat tube in which a plurality of holes are partitioned by a plurality of inner pillars arranged in parallel in the width direction inside the outer peripheral wall,
A female die having an opening that molds the outer shape of the flat tube, and a male die that is combined with the female die and has a mandrel that is disposed in the opening and shapes the inner pillar and the hole,
The mandrel has a plurality of molding projections corresponding to the holes and a plurality of slits corresponding to the inner pillars.
Of the molding projections, end molding projections located at both ends in the width direction are formed with shoulders protruding outward in the width direction on the root side, and the width of the end molding projections in the shoulders is set. An extrusion die for a multi-hole flat tube, characterized in that it is set at least twice the width of the end forming convex portion at the tip at a position at least half the depth of the slit from the tip. The extrusion die for a multi-hole flat tube according to claim 1, wherein a front surface of the shoulder portion in the extrusion direction is opposed to the female die and is perpendicular to the extrusion direction.

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