KR101820812B1 - Bonding method for cooling line of die-casting mold using explosive welding - Google Patents

Abstract

The present invention relates to a cooling channel heterogeneous bonding method of a die casting mold using explosion dilation and a die casting die formed by the method. The objective of the present invention is to bond a copper tube integrally with a cooling hole of a die cast die heat- A method of joining a cooling channel of a die casting mold using an explosion-expanding device capable of improving the productivity and cooling efficiency of the die casting mold and extending the life of the die, and a die casting die formed by the method.
According to the present invention, there is provided a method of manufacturing an extrusion pipe, comprising the steps of: processing an expansion pipe in accordance with the length and shape of a copper pipe which is differentially bonded to a cooling hole of a die casting mold; An explosive installation step of inserting a string explosive into the explosive injection hole; A copper tube inserting step of inserting a copper tube into the cooling hole such that a constant gap (G) with the cooling hole is maintained; Installing an extension pipe through which the extension pipe is inserted into the copper pipe; A copper tube joining step in which the explosive energy of the line explosive is transmitted to the expansion tube by explosion of the line explosive due to the electric primer and the expansion tube is expanded and expanded in the direction of the copper tube by the explosion energy and the copper tube is bonded to the inner surface of the cooling hole , A die casting die in which a copper tube having an excellent thermal conductivity is integrated by explosive expansion in a cooling hole is manufactured.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for bonding a cooling channel of a die casting mold using explosion-

The present invention relates to a cooling channel heterogeneous bonding method of a die casting mold using explosion dilation, and more particularly, to a cooling channel heterogeneous joining method of a die casting mold using explosion dilation, in which a tube of dissimilar materials having low strength is joined to a cooling hole To a cooling channel heterogeneous bonding method of a casting mold.

In general, die casting is a precision casting method in which a molten metal is injected into a precisely machined mandrel so that it exactly matches the required casting shape, thereby obtaining the same casting as the die. This die casting method requires precise dimensions of the casting In addition to its almost no merit, it has excellent mechanical properties and mass production capability.

Three important factors of the die casting method are the mold (product shape, casting plan), the casting machine (casting condition), the material (alloy characteristics, melting and melt processing), and the quality, price and productivity of the product are determined by these three factors . Among them, the die not only directly affects the quality and productivity of the die cast product, but also has the highest ratio of 70% to the production cost.

Especially, in case of die casting mold for casting transmission which is the core of automobile automatic transmission, unlike a general mold, it has complicated flow path and thick thickness shape, and has a large thickness deviation and high level of technical skill The die casting die for casting such transmission determines the dimensional accuracy of the product and the die life according to the cooling performance.

The die casting method is a method of coagulating and cooling by injecting into a mold at a high temperature of about 650 DEG C or more and a high pressure of 700 kg / cm < 2 > during the production of the product, and injecting the mold into the mold by air pressure, water pressure, In order to adjust the temperature of the mold, the die casting die is connected to the water supply and drainage lines from the outside to form a cooling line for supplying and discharging cooling water for cooling the inside of the mold.

The die used for the die casting is a metallic mold and is divided into a movable side mold and a fixed side mold as shown in Fig. 1, and a product shape is formed between the movable side mold and the fixed side mold And a cooling line is formed in a holder in which the stationary-side mold and the stationary-side mold are fixed so as to be spaced apart from the cavity by a predetermined distance.

However, in the conventional die casting mold, that is, in the stationary side mold, the cooling holes are firstly processed by a straight drill, The cooling holes are secondarily machined by a ball end mill to directly drill a cooling line so as to be spaced apart from the cavity by a predetermined distance. Then, cooling water at a low temperature is supplied through the cooling line thus processed, The cooling water is directly brought into contact with the cooling water,

The cooling water of low temperature is directly brought into contact with the end portion of the cooling hole of the mold and cracks (stress corrosion cracking due to thermal expansion shrinkage) are caused by the high temperature thermal fatigue due to the repeated cycle, , There is a problem that leakage of cooling water occurs and it is difficult to secure a product defect and a worker's safety.

Further, due to the above-described problems, the gap d between the cavity and the cooling hole is set to about 20 mm or more, which causes various problems such as a limitation in cooling performance.

In order to solve the above-mentioned problems, there is a method (Patent Registration No. 1487215) in which a cooling channel of a die casting mold is bonded by explosion welding, which is filed and registered by the applicant of the present invention,

In the case of explosion welding, the explosive force of the explosive is directly transmitted to the cooling holes of the copper tube and the mold. When the annealing is performed after the roughing operation before the heat treatment, the copper tube is bonded to the cooling hole without damaging the mold,

When the explosive welding is performed on a mold having a high strength and hardness by a heat treatment (a heat-treated mold), cracks are generated in the mold itself due to the explosion energy caused by explosion welding, there was.

That is, the die casting mold material is made of SKD61 and DAC-P materials, and all the molds of SKD61 and DAC-P materials are subjected to the QT process. When explosive welding is performed on the heat treated mold, Cracks are likely to be generated in the mold itself due to the explosive force, and after the heat treatment, there is a problem that the dissimilar materials can not be bonded to the cooling channel by the explosion welding.

In addition, direct explosion of the explosive may not only contaminate the inside of the copper tube, but also may not have a uniform bond thickness throughout the entire cooling channel, and partially cured tissue may be generated. Such a hardened portion is liable to advance to a fine crack with the lapse of time.

Also, in the case of the repair die casting mold and the regenerating mold, many fine cracks remain in the cooling channel and the mold cavity portion, and when the conventional copper pipe is bonded by conventional explosion welding, the risk of breakage of the mold becomes very large And the like.

Published Patent Publication No. 10-2009-0000389 (2009.01.07) Disclosure of the Invention Disclosure of the Invention Problems to be Solved by the Invention Open Patent Publication No. 1998-016129 (May 25, 1998) Published Patent Publication No. 95-16983 (July 20, 1995)

It is an object of the present invention to provide a method of manufacturing a die casting die having a structure in which a copper tube is integrally and wholly bonded to a cooling hole of a die casting die subjected to heat treatment by explosion expansion to improve the productivity and cooling efficiency of the die casting die, And to provide a cooling channel heterogeneous bonding method for a die casting mold using the same.

According to the present invention, there is provided a method of manufacturing an extrusion pipe, comprising the steps of: processing an expansion pipe in accordance with the length and shape of a copper pipe which is differentially bonded to a cooling hole of a die casting mold; An explosive installation step of inserting a string explosive into the explosive injection hole; A copper tube inserting step of inserting a copper tube into the cooling hole such that a constant gap (G) with the cooling hole is maintained; Installing an extension pipe through which the extension pipe is inserted into the copper pipe; A copper tube joining step in which the explosive energy of the line explosive is transmitted to the expansion tube by explosion of the line explosive due to the electric primer and the expansion tube is expanded and expanded in the direction of the copper tube by the explosion energy and the copper tube is bonded to the inner surface of the cooling hole To produce a die casting die in which a copper tube having excellent thermal conductivity is integrated into the cooling hole by explosive welding.

The present invention is applicable to die casting molds, repair die casting and regenerating die casting molds in which the copper tubes are integrally joined together by the line explosion in the cooling hole of the die casting mold and the expansion pipe expansion by the expansion pipe and the strength and hardness are increased by the heat treatment , Dissimilar metals having excellent thermal conductivity can be integrally bonded to the cooling holes without damaging and damaging the mold.

According to the present invention, an expansion pipe is machined in accordance with the shape and length of a dissimilar metal (copper pipe) joined in a cooling hole of a metal mold, and an explosive insertion hole in which a string explosive is installed is formed The entire expansion tube is uniformly expanded by the explosive energy of the joule explosion and the explosive energy of the jumping explosion is transferred to the entire copper tube by the uniform expansion of the expansion tube to connect the copper tube in the cooling hole, The bonding of the dissimilar metals is also achieved by the jumping of the amount.

The present invention has a dual structure in which a copper tube is integrated by explosive expansion in a cooling hole of a die casting mold, so that leakage of cooling water is prevented, and the cooling hole is formed as close as possible to the cavity to further improve the cooling efficiency have.

That is, conventionally, due to the generation of cracks (stress corrosion cracking due to thermal expansion shrinkage) in the mold due to high temperature thermal fatigue, the gap between the cavity and the cooling water line is set at about 20 mm or more. However, Even if it is set to be maintained within about 5 mm, the conventional problem does not occur.

In the present invention, since the cooling line of the die casting mold has a double structure, it can withstand repeated high temperature thermal fatigue for a long time, thereby further improving the lifetime of the mold.

The present invention has excellent cooling performance, and when applied to a transmission mold which is a core part of an automotive transmission, it is possible to improve the dimensional accuracy of the product, improve the product quality, reduce the mass production of defective products, have.

In other words, the present invention is manufactured by using explosion expansion by inserting a Cu Bush having excellent corrosion resistance and excellent thermal conductivity, thereby being able to withstand repeated high temperature thermal fatigue for a long time, (Maintenance of mold temperature), it is possible to increase the life of complex die casting molds such as Transmission molds (longer life), to improve product quality and productivity, to secure manufacturing cost competitiveness by longevity improvement and to prevent fatigue cracks in DC mold cooling water line part Thereby preventing the cooling water from leaking.

The present invention can be installed without changing the structure of the conventional die casting mold, and since the die casting mold can be sold as a single part or a part of the die, the quality of the large die casting mold and the insert die part can be greatly improved, It is possible to improve the cooling efficiency of the mold and to prolong the life span of the mold.

The present invention can be applied not only to a die casting die before and after heat treatment, a die casting die after roughing, but also to a casting mold such as low pressure and gravity and a plastic forming die.

FIG. 1 is an exemplary view showing a die casting die in which a cooling hole is formed
FIG. 2 is a block diagram showing a heterogeneous bonding process according to the present invention. FIG.
FIG. 3 is an exemplary view showing a configuration of a cooling hole according to the present invention
FIG. 4 is a view showing an example of an installation state of a line explosion and an expansion pipe in a cooling hole according to the present invention. FIG.
5 is an exemplary view showing a bonded cross section according to an embodiment of the present invention
6 is an exemplary view showing a result of conventional explosion welding
Fig. 7 is an exemplary view showing a load according to explosion expansion according to the present invention

The die casting mold 10 is divided into the movable mold 11 and the stationary mold 12 and the movable mold 11 and the stationary mold 12, A cavity 13 is formed between the molds 12 in a product shape and a cooling hole 20 is formed in the fixed mold 12 so as to be spaced apart from the cavity 13 by a predetermined distance. At this time, the cooling hole 20 is formed in a cylinder type with one side closed.

The cooling hole 20 has a main cooling hole 21 and a copper pipe 21 so as to form a layer with the main cooling hole 21, And an extension fixing hole 22 for fixing the base 30.

The main cooling hole 21 is a substantial cooling line through which coolant is supplied and discharged. The main cooling hole 21 has a cooling hole end 23 having a round shape and a cooling hole 23 formed integrally with the cooling hole end 23 and having a cylindrical shape. And a hole leading end 24. That is, the main cooling hole 21 has a predetermined depth and is formed in the mold in a groove shape having one end opened and the other end closed.

The enlarged fixing hole 22 is for fixing the copper tube 30 and is formed to have a predetermined depth from the entrance side of the main cooling hole 21, that is, the surface of the mold, and is larger than the main cooling hole 21 And is formed in the mold so as to have the same center line CL as that of the main cooling hole 21. That is, the main cooling hole 21 and the extension fixing hole 22 are formed so as to communicate with each other, and are formed in the mold by a processing means (not shown) such as a drill.

FIG. 2 is a block diagram showing a heterogeneous bonding process according to the present invention, FIG. 3 is a view showing the structure of a cooling hole according to the present invention, FIG. 4 is a cross- FIG.

The present invention is characterized in that the extension pipe 90 is machined in accordance with the length and shape of the copper pipe 30 which is differentially bonded to the cooling hole 20 of the die casting die, (91);

An explosive installation step of inserting a string explosive 40 into the explosive insertion hole 91;

Inserting a copper tube (30) into the cooling hole (20) so that a constant gap (G) with the cooling hole (20) is maintained;

Installing an extension pipe (90) into the copper pipe (30);

The explosive energy of the jellyfish 40 is transmitted to the expansion tube 90 by the explosion of the jelly explosion 40 by the electrical primer 80 and the explosion energy causes the expansion tube to explode in the direction of the copper tube 30 And a copper tube joining step for joining the copper tube 30 to the inner surface of the cooling hole 20 by being expanded.

The outer diameter D3 of the extension pipe 90 is adjusted so that the shape and length of the inside 33 of the copper pipe 30 bonded to the cooling hole 20 of the metal mold are matched with the shape and length of the inside 33 of the copper pipe 30, Is formed to have a small tolerance of 0 to 0.2 mm larger than the inner diameter D2 and the length L3 of the extension pipe is formed so as to have the same or more than the inner length L2 of the copper pipe.

An explosive insertion hole 91 is formed in the longitudinal direction of the extension pipe 90 for installing the string explosive 40. The explosive insertion hole 91 is formed in one side And the depth is machined such that the other side has an interval S of about 2 to 4 mm from the end round portion 92 of the extension pipe. Such an interval S is set so that the copper tube round portion 34 is accurately bonded to the cooling end 23 of the cooling hole and the cooling end 23 and the copper tube round portion 34 ). ≪ / RTI >

At this time, the inner diameter D4 of the explosive insertion hole 91 is formed to be about 3.5 to 5 mm according to the string explosive 40 to be installed.

The expansion tube 90 thus formed is expanded by the explosive energy of the jellyfish 40 so that the copper tube 30 is bonded to the cooling hole 20. In addition, the extension tube 90 is made of polyethylene, preferably high density polyethylene.

The expansion tube 90 made of high-density polyethylene has a function of uniformly expanding the explosion energy of the explosive by the explosive energy by the jumping explosion 40, and transmitting the explosive energy of the explosive explosion to the copper tube 30. That is, the expansion tube made of the high-density polyethylene does not merely absorb the explosion energy due to explosion of the juncture explosion 40 to reduce it, but functions to distribute and distribute the explosion energy uniformly. .

The expanding tube processing step may be performed on the outer surface 93 of the extension pipe 90 which is in contact with the inside of the copper pipe 30 or on the inner surface or outer surface 93 of the explosive injection hole 91 ) And the inner surface of the explosive injection hole (91).

The plasma surface-treated outer surface 93 or the inner surface of the explosive injection hole 91 has a contact angle of 110 ° to 160 ° so that the explosive energy by the jolt explosive 40 is uniformly distributed in the expansion pipe 90 The expansion energy of the expansion pipe 90 due to the explosion energy is uniformly transferred to the copper pipe 30 so that the copper pipe 30 is tightly bonded to the cooling hole 20.

The configuration of the extension pipe 90 and the length and depth of the extension pipe 90 are such that the explosive energy generated by the luffal 30 is uniformly transferred to the copper pipe 30, So as to stably adhere tightly.

The step of installing the explosives is to insert the junebun explosive 40 into the explosive insertion hole 30 of the extension tube 90 and to insert the juniper explosive 40 into the expansion tube 90 Into a string explosive insertion hole (91) formed in the longitudinal direction of the string; A primer installing step of connecting an electrical primer 80 to an upper end of the string explosive 40; .

The line explosive 40 is a line type in which a small amount of explosives are inserted therein. When one of the explosives is exploded, all the explosives connected in a very short time are exploded. The explosive propagation speed of the juniper explosive 40 is about 6,800 m / sec, which is very fast, so that the explosives are connected to each other at almost the same time.

When the inner diameter of the cooling bore is more than 12 mm, 10 g / m < 2 > is provided, and when the inner diameter of the cooling hole is 12 mm or less,

When 10g / m of juniper explosive is installed, the explosive installation hole inner diameter of the extension pipe is set to 5mm, and when 5g / m of row explosive is installed, the explosive installation hole inner diameter of the expansion pipe is 3.5mm .

The length of the explosive installation hole (maintaining the interval S of about 2 to 4 mm from the end round portion 92 of the extension pipe) In order to optimize the expansion of the expansion tube 90 in consideration of the magnitude of the explosive 30, that is, the expansion of the expansion tube 90, the copper tube 30 is efficiently and efficiently bonded to the cooling hole 20 So that the copper pipe round portion 34 of the copper pipe is closely adhered to the cooling end of the cooling hole.

The step of installing the copper tube includes the step of inserting the copper tube 30 into the cooling hole 20 formed in the mold and removing the foreign substance in the cooling hole 20 and inserting the copper tube 30 into the cooling hole 20, .

At this time, the upper flange 32 of the copper tube is fitted into the extended fixing hole 22 of the cooling hole, the body 31 of the copper tube is inserted into the main cooling hole 21, It is preferable that the main cooling hole 21 and the copper tube body 31 are maintained at a gap G within about 0.3 to 0.6 mm by fitting the flange 32 and the fixed fixing hole 22, Is maintained.

That is, the copper tube 30 is formed such that the diameter of the upper flange 32 is the same as the diameter of the enlarged fixing hole 22 of the cooling hole, and the copper tube body 31 is formed to have a diameter of about 0.3 And is formed to maintain a gap G of within 0.6 mm and a thickness t of 2 to 3 mm.

The expansion tube installation step includes inserting the expansion tube 90 into the copper tube 30 whose position is fixed in the cooling hole 20. At this time, the extension pipe 30 is inserted into the inside of the copper pipe 30 in a state where the junk explosion 40 is inserted into the explosive insertion hole 91, or the expansion pipe 90 The string explosive 40 can be inserted into the explosive insertion hole 91 of the extension pipe 90. [

When the string explosive 40 is installed in the explosive insertion hole 91 as described above, the end of the string explosive 40 is spaced from the end round 92 of the extension tube by about 2 to 4 mm. .

The step of joining the copper tube is a step of joining the copper tube 30 into the cooling hole 20 by the expansion of the expansion tube 90, The explosive 40 is exploded and the expanding tube 90 is expanded in the copper tube inner wall 31 by the explosive energy of the string explosive and the inner surface of the cooling hole 20 is expanded by the expansion of the expansion tube 90, The pipe 30 is joined.

The die casting die formed by the above method is formed such that a copper tube having a good thermal conductivity is bonded to the copper tube by the explosion expansion in the cooling hole and the gap d between the cavity and the cooling hole is maintained within about 5 mm .

In addition, the explosion pipe of the present invention as described above is adapted to connect a copper pipe to a cooling hole of a heat-treated die casting mold, but it is also applicable to bonding of a copper pipe in a cooling hole of a die casting mold before heat treatment.

Hereinafter, the present invention will be described in detail with reference to Examples.

Example

A copper tube (thickness 2 mm) was inserted and placed in a cooling hole (diameter 15 mm, length 100 mm) of the heat-treated mold SKD61 so as to maintain a gap of 0.5 mm, and the outer surface of the expansion tube The copper tube was connected to the cooling hole by expanding the extension tube by 10g / m of the jade explosion, and the result is shown in Fig.

At this time, the explosive insertion hole of the extension pipe had a diameter of 5 mm, and the depth of the explosive insertion hole was set so as to maintain a gap S of about 3 mm from the end round portion of the expansion pipe.

FIG. 5 is a view illustrating an example of a bonded cross-section according to the present invention. It can be seen that a copper tube is integrally bonded to a cooling hole of a heat-treated metal mold in close contact with each other.

Comparative Example

A copper tube was inserted into a cooling hole of a heat-treated mold (SKD61) under the same conditions as those of the embodiment, a string explosive was installed in a copper tube, a cap was provided on the inlet side of the cooling hole, The copper tube was bonded to the cooling hole by explosion expansion, and the result is shown in Fig.

FIG. 6 shows the results of conventional explosion welding. When a copper tube is bonded to a cooling hole by explosion welding without installing an extension tube, it is seen that the copper tube is not bonded but the mold is damaged have. In case of explosion welding, it is required to have a speed of about 1500 m / s or more. However, if the copper tube is bonded at a speed of 1500 m / s to the heat-treated mold, the explosion energy is unevenly distributed in the mold, When dispersed, the mold itself was broken.

FIG. 7 is a graph showing a load according to the explosion expansion according to the present invention. In the case of explosion welding, a load value of about 100 KN is shown, but the explosion expansion according to the present invention is about 20 to 30 KN. The copper tube can be stably and adhered to the hole without being damaged or broken.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents. Of course, such modifications are within the scope of the claims.

(10): die casting mold (11): movable mold
(12): stationary side mold (13): cavity
(20): cooling hole (21): main cooling hole
(22): extended fixing hole (23): cooling end
(24): cooling stand (30): copper tube
(31): copper pipe round section (40): string explosion
(80): electrical primer (90): expansion tube
(91): Explosive insertion hole (92): End round part
(93): outer surface

Claims (5)

A cooling channel heterogeneous joining method for a die casting mold in which a tube of a different material having a low strength is joined to a cooling hole integrally by an expansion of an expansion tube in a cooling line of a heat-treated die casting die,
The expansion tube 90 made of high-density polyethylene is processed in accordance with the length and shape of the copper tube 30 which is differentially bonded to the cooling hole 20 of the die casting mold 10, An expanding tube processing step of processing the explosive insertion hole 91;
An explosive installation step of inserting a string explosive 40 into the explosive insertion hole 91;
Inserting a copper tube (30) having a thickness (t) of 2 mm into the cooling hole (20) so that a gap (G) within 0.3 mm to 0.35 mm is maintained with the cooling hole (20);
Installing an extension pipe (90) into the copper pipe (30);
The explosive energy of the jellyfish 40 is transmitted to the expansion tube 90 by the explosion of the jelly explosion 40 by the electrical primer 80 and the explosion energy causes the expansion tube to explode in the direction of the copper tube 30 And a copper tube joining step of joining the copper tube (30) to the inner surface of the cooling hole (20)
The explosive injection hole 91 has a shape in which one side is open for installation of the juniper explosive 40 and the other side has an interval S of about 2 to 4 mm from the end round portion 92 of the expansion tube And is processed to have a depth,
The expanding tube processing step may include an outer surface 93 of the extension pipe 90 that is in contact with the inside of the copper pipe 30 or an inner surface 93 or an outer surface 93 of the explosive injection hole 91, And a surface treatment step of plasma-treating the inner surface of the explosive injection hole (91)
The surface treatment step is surface-treated so that the outer surface 93 of the extension tube or the inner surface of the explosive injection hole 91 has a contact angle of 110 ° to 160 °,
Wherein the dissimilar metals having excellent thermal conductivity can be integrally joined to the cooling holes without damaging or breaking the die casting mold whose strength and hardness are increased by the heat treatment.
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