GB2088765A - Extrusion die for producing profiled products having fins - Google Patents

Abstract

An extrusion die (10) is provided with a plurality of juxtaposed tongues (13) for forming fins in extruded profiled metal. The tongues (13) have reinforcing portions (13B) which are located at the upstream side of the profile defining bearing portions (13A) thereof in the direction of extrusion. With this location of the reinforcing portions, the reinforcing portions may be contacted with the metal to be extruded without requiring the thickness of the reinforcing portions to be reduced, thereby permitting thin fins located closely to each other to be extruded, because the tongues are sufficiently reinforced so that they may be thinned and located closely to each other. <IMAGE>

Description

SPECIFICATION Extrusion die for producing profiled products having fins The present invention relates to an extrusion die provided with a plurality of juxtaposed or parallel arranged tongues for forming fins in the extruded profiled metal.

A profiled metal having a plurality of fins has been extruded heretofore by using an extrusion die having a plurality of juxtaposed tongues for defining the gaps between the adjacent fins.

Each tongue has a very narrow width, such as less than 3 mm, in comparison with its large height and, therefore, is liable to be broken. In order to avoid the fracture of the tongues, they have been formed heretofore in elongated shape extending in the direction of extrusion so as to enhance the strength thereof and, at the same time, undercut or relieved portions have been formed in the downstream side of the bearing surfaces of the tongues for defining the configuration of the fins in the extruded metal so that such relieved portions will not contact with the extruded metal, thereby reducing frictional resistance and preventing fracture of the tongues during the extrusion.

In such a configuration of the tongues, however, the relieved portions of the tongues become extremely thin, when the gap between the adjacent two fins in the extruded metal is less than 1 mm, and the relieved portions do not serve as reinforcing portions for the bearing portions thereby leading to fracture of the tongues. On the other hand, if the relieved portions are made small to enhance the strength of the tongues, the contact areas of the tongues with the extruded metal become greater, thereby rendering the plugging or blockage of the flow of the metal at these relieved surfaces liable to occur.

For the reasons described above, it has been thought that stable production of extruded metal provided with a plurality of fins arranged in juxtaposed or parallel arranged relation closely spaced from each other would be difficult or impossible.

The present invention aims at avoiding the above described difficulties in the prior art extrusion die.

Therefore, it is an object of the present invention to provide a novel and useful extrusion die having a plurality of tongues capable of forming thin fins arranged very closely to each other in the extruded profiled metal under the stable and steady conditions, such a narrow gap between the adjacent two fins in the extruded profiled metal having been heretofore thought to be extremely difficult or impossible to obtain.

An extrusion die in accordance with the present invention is provided with a plurality of juxtaposed tongues for forming fins in the extruded profiled metal, wherein the tongues have reinforcing portions which are located at the upstream side of the profile-forming bearing portions thereof in the direction of extrusion.

With the above described construction of the extrusion die, the reinforcing portions may contact with the extruded metal, because the final contour of the fins of the extruded metal is defined by the bearing portions of the tongues located at the downstream side of the reinforcing portions, and the thickness of the reinforcing portions is not required to be reduced contrary to the case of the prior art extrusion die, thereby providing sufficient strength to the reinforcing portions. Therefore, the tongues can be made very thin to permit very small gaps to be formed between the adjacent fins, while the gaps between the adjacent tongues can be made very small, thereby permitting very thin fins to be formed by the extrusion die of the present invention.

Additional reinforcing portions may also be provided at the downstream side of the bearing portions in the direction of extrusion as in the case of the prior art extrusion die.

The present invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a fragmentary perspective view showing an example of the extruded profiled metal produced by using an extrusion die; Figure 2 is a front view showing an example of the prior art extruding die used in producing the extruded profiled metal shown in Fig. 1; Figure 3 is a cross-sectional view of Fig. 2; Figure 4 is a perspective view showing the first embodiment of the extrusion die in accordance with he present invention for producing an extruded profiled metal having a plurality of fins therein; Figure 5 is a vertical longitudinal sectional view of the extrusion die of Fig. 4; Figure 6 is a horizontal longitudinal sectional view of the extrusion die of Fig. 4; Figure 7 is a front view showing the configuration of the extruded profiled metal;; Figure 8 is an exploded perspective view showing a second embodiment of the extrusion die of the present invention; Figure 9 is a perspective view showing a third embodiment of the extrusion die of the present invention; Figure 10 is a longitudinal sectional view of the extrusion die of Fig. 9; Figure 11 is a sectional view similar to Fig. 10 but showing an alternative form of extrusion die; Figure 12 is a fragmentary sectional view showing another embodiment of the extrusion die adapted to be used in a continuous extruding machine; Figure 13 is a cross-sectional view showing the configuration of the profiled metal extruded by using the extrusion machine and die shown in Fig. 12; Figure 14 is a longitudinal sectional view showing still another embodiment of the extrusion die of the present invention adapted to be used in a discontinuous extruding machine; and Figure 15 is a cross-sectional view of the profiled metal extruded by using the die shown in Fig. 13.

Prior to the description of the present invention, brief description of the prior art extrusion die is given below with reference to Figs. 2 and 3.

The extrusion die 2 shown in Figs. 2 and 3 has a plurality of juxtaposed tongues 2A formed in the extruding orifice of the die 3 for defining the clearance between the adjacent two fins 1A in the extruded profiled metal 1 as shown in Fig. 1.

As shown in Fig. 2, the tongue 2A has a very narrow width in comparison with its large height so that the tongues are liable to be broken when the width is reduced beyond a certain value such as 3 mm, for example In order to avoid the fracture of the tongues 2A, the depth or the length of the tongues in the direction of extrusion is made large as shown in Fig. 3 so as to enhance the strength of the tongues 2A, while undercut or relieved portions 2C are formed at the downstream side of the bearing portions 2B in the direction of extrusion so that the relieved portions will not contact the extruded profiled metal, the bearing portions 2B being for defining the profile of the fins 1A.

However, if the clearance between the fins 1 A is made smaller than 1 mm, for example, the relieved portions 2C become extremely thin and sufficient strength cannot be imparted by the relieved portions 2C so that the tongues are liable to be broken.

On the other hand, if the relieved portions 2C are not formed, which means prolonged bearing portions 2B, contact will take place between the entire area of the tongues 2A and the extruded metal, thereby rendering blockage or plugging of the metal liable to occur at the bearing portions 2B. This makes it very difficult or impossible to produce an extruded profiled metal having fins located very closely to each other by using the prior art extrusion die 2.

The above difficulties can be obviated by the extrusion die constructed in accordance with the present invention, which will be described below with reference to Figs. 4 to 1 5.

Referring now to Figs. 4 to 6, showing the first embodiment of the extrusion die 10 of the present invention, it is constructed by a die body 11 and a tongue structure 1 2 in which a plurality of tongues 1 3 consisting of bearing surfaces 1 3A and reinforcing portions 1 3B are formed. As seen in these figures, the reinforcing portions 1 3B are located at the upstream side of the bearing surfaces 1 3A in the direction of extrusion indicated by the arrow.

The die body 11 is formed with bearing surfaces 11A conforming with the contour or profile S indicated by the solid line in Fig. 7 and appropriate undercut portions 11 B are formed at the downstream side of the bearing surfaces 11 A, the bearing surfaces 1 1 A being determined for defining the outside profile or contour S of the extruded metal.

The tongue structure 1 2 may be formed by a separate block and the tongues 1 3 are provided by forming a plurality of grooves 14 in the upper portion of the block. The bearing surfaces 1 3A formed at the rear ends of the respective tongues 1 3 are so located that they lie opposite to the bearing surfaces 1 A of the die body 11 while they contact at their lower sides with portions of the lower bearing surface 1 1 A as shown in Figs. 5 and 7.Thus, the bearing surfaces 1 3A of the tongues 1 3 define the contour or profile S' indicated by one dot-chain line in Fig. 7, so that the extrusion orifice shown in Fig. 7 is formed in the die body 11, if the tongue structure 1 2 made separately beforehand the orifice shown in Fig. 7 is formed, and it is assembied with the die body 11 in its proper relative position and secured fixedly to each other by suitable means (not shown).

In these figures, the thickness of the portions at the bearing surfaces 1 3A is shown as the same as that of the reinforcing portions 1 3B. However, the thickness of the portions at the bearing surfaces 11 3A may be gradually increased or decreased in the direction of extrusion by forming the bearing surfaces 1 3A in the curved or stepped configuration.

The size of the reinforcing portions 1 3B is set so as to give sufficient strength to bear against the force of extrusion, while the shape of the reinforcing portions 1 3B is so determined that the metal to be extruded can be pushed easily into the grooves 14.

To this end the upstream ends of the tongues 1 3 in the direction of extrusion terminate in the inclined upper surface 1 2A of the tongue structure 12. The angle a of inclination of the surface 124 is selected in general to be in the range of 90 to 30 , taking into consideration the flow of metal during the extrusion. However, the angle a may be greater than 90 by appropriately limiting the flow of metal by using a front plate ring.

With the extrusion die 10 constructed as described above, it is not necessary to provide relieved portions in the reinforcing portions 1 3B located at the upstream side of the bearing surfaces 13A, because it is no more necessary to avoid the contact of the reinforcing portions 1 3B with the extruded profiled metal. The reinforcing portions 1 3B are so constructed that the metal to be extruded flows uniformly without causing any hindrance to the flow, while they serve to prevent fracture of the bearing surfaces 13A.

Therefore, the reinforcing portions 1 3B may be made parallel to each other so as to most advantageously increase the cross-sectional area thereof to enhance the strength. However, they may be made other configuration than the above.

Since the die body 11 is formed with a relieved or undercut portion 1 1C at the downstream side of the bearing surface 13A, the contact of the extruded profiled metal with portions of the die body 11, after it has been profiled, is completely avoided. Therefore, the clearance between the fins in the extruded profiled metal can be made extremely small by using the extrusion die of the present invention in comparison with the case using the prior art extrusion die.

The above described die is shown as having a tongue structure separate from the die body.

However, the tongue structure may be made integral with the die body. The front edges of the tongues 1 3 terminate in the inclined plane surface 12A. However, the surface 1 2A may be made a curved surface or the front edges may be chamfered or rounded so as to appropriately guide the flow of the metal.

Further, additional reinforcing portions may be provided at the downstream side of the bearing surfaces 1 3A as in the case of the prior art insofar they are configured so as not to cause the plugging or blockage of the flow of metal at the bearing surfaces 13A.

Further, the die 10 may be provided with a plurality of extrusion orifices so as to produce simultaneously the same number of extruded profiled metal as that of the extrusion orifices.

Fig. 8 shows the second embodiment of the extrusion die 20 of the present invention constructed as the porthole type.

The die 20 is determined to produce a hollow profiled metal having fins in its outer surface, and it comprises a porthole die body 21 for defining the hollow portion of the extruded metal, a die body 22 for defining the outer profile except the portions where fins are formed, tongue structures 23 for defining the profile of the fins arranged at both sides of the extruded metal and a die ring 24 for securing the die body 21 and the die body 22 to each other. In this embodiment, each tongue structure 23 is constructed in similar way to the tongue structure 1 2 shown in Fig. 4, and they are fixedly secured to the die body 22 or they are constructed integrally with the die body 22, and, further, a mounting structure for securing the tongue structures 23 may be constructed by securing the die body 22 to the die ring 24.

Further, fins may be formed in the inside of the hollow extruded metal by forming grooves in the bearing portion 21 a of the porthole die body 21.

When the porthole die body 21 is not used, then the hollow portion of the extruded metal is filled with metal to form a solid extruded metal.

Further, a vertically flat extruded metal having fins in both side surfaces can be produced by positioning the two tongue structures 23,23 in closely spaced relationship to each other.

Figs. 9 and 10 show the third embodiment of the extrusion die 30 of the present invention wherein, contrary to the preceding embodiments, a tongue structure 32 is located in the interior of a die body 31.

The die body 31 has bearing surfaces 31A for defining the outer profile of the extruded metal except the portions where fins are formed, while the tongue structure 32 is provided with tongues 32A for defining the profile of the fins, and the tongue structure 32 is fitted in the cutout portion of the die body 31 so that the die body 31 and the tongue structure 32 form a circular disc as a whole.

The outer configuration of the die 30 is made the same as a conventional die so that it can be easily used in a conventional extruding machine. The die 30 has also advantage that the flow of metal can be lead uniformly to the bearing surfaces substantially from the entire circumference of the die.

In this embodiment, the tongue structure 32 can be secured fixedly to the die body 31 by any suitable means.

The tongue structure 32 functions in the similar manner as in the preceding embodiments.

Further, the tongue structure 32 may be constructed integrally with the die body 31 depending on the configuration of the bearing surfaces.

The angle a of the tongues 32A may also be made 90" or greater as shown in Fig. 11.

The test results of the extruded profiled metal produced by using the die constructed in accordance with the present invention will be described below with reference to Figs. 1 2 to 1 5.

Test I (Continuous Extrusion) Using a continuous extrusion machine manufactured by United Kingdom Atomic Energy Authority (UKAEA) the die portion of which is shown in Fig. 12, continuous profiled metal strip having the cross-sectional configuration as shown in Fig. 1 3 was produced by continuous extrusion process. The extrusion machine included a rotating wheel 40 having circular grooves 40A in its periphery as was well known, and the metal to be extruded was forcibly fed along the grooves 40A as the wheel 40 rotated so that the metal was driven out of the grooves 40 by the abutment 41A of the die ring 41 slidably fitted in the grooves 40, and continuously extruded through the extrusion orifice formed by the die body 42 and the tongue structure 43.

The configuration of the cross-section of the extruded metal as shown in Fig. 1 3 was: d = 0.7 mm h = 4.7 mm t = 1 mm w = 6.2 mm The tonge structure and the extrusion machine were as follows: Angle a of the front edge of the tongue: 60 Length of the tongue in the direction of extrusion: 8 mm Undercut of the die body: 2 mm Diameter of the wheel: 340 mm Diameter of the metal rod supplied 9.5 mm Kind of alloy: 1050 Extrusion ratio: 4.0 Temperature: room temperature Extrusion velocity: 80 m/min The results were satisfactory in that the product has no deficiency and the die was proved to be practical for use in production.

Test II (Discontinuous Extrusion) Using a conventional extrusion machine as shown in Fig. 14, extruded profiled metals having the cross-sectional configuration shown in Fig. 1 5 were produced by using a die body 53, a tongue structure 54 and the front plate ring 55 for improving the flow of metal during the extrusion. The extrusion machine included a container 50, a liner 51 and a dumming block 52.

The test data were as follows: d = 1 mm h = 6 mm t = 1.0 mm w = 9 mm Angle a of the front edge of the tongue: 55 Length of the tongue in the direction of extrusion: 6 mm Undercut of the die body: 2 mm Diameter of the billet: 150 mm Kind of alloy: 1050 Length of the billet: 400 mm Extrusion ratio: 480 Temperature: 500"C Extrusion velocity: 50 m/min The test results were satisfactory and extruded profiled products having no deficiency were obtained and the practicability of the die of the present invention in the actual production was proved.

Claims (5)

1. An extrusion die provided with a plurality of juxtaposed tongues for forming fins in the extruded profiled metal, wherein the tongues have reinforcing portions which are located at the upstream side of the profile-forming bearing portions thereof in the extrusion direction.

2. An extrusion die as claimed in claim 1, wherein additional reinforcing portions are located at the downstream side of said tongues in the extrusion direction.

3. An extrusion die as claimed in claim 1 or 2, wherein the reinforcing portions have forward edges which are inclined to the cross-sectional plane of the bearing portions defining tho profile.

4. An extrusion die as claimed in claim 1, 2 or 3, which comprises a die body having therein an opening defining the outer periphery of the profile and a separate tongue structure mounted on the die body at the upstream side thereof with the profile-forming bearing portions of the tongues located in said opening.

5. An extrusion die constructed substantially as herein described with reference to and as illustrated in Figs. 4 to 6, 8 to 1 2 and 14 of the accompanying drawings.