Description:FORM 2
The Patent Act 1970
(39 of 1970)
and
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“OPTIMIZED FEED RUNNER SYSTEM FOR HIGH PRESSURE DIE CASTING OF AUTOMOTIVE COMPONENTS”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Chh. Sambhajinagar – 431136 (formerly Aurangabad),
Maharashtra, India

The following specification describes the nature of the invention and the manner in which it is to be performed.

Field of Invention

[001] The present invention relates to an optimized feed runner system for high pressure die casting of automotive components. More particularly, the invention is related to a feed runner system having an intelligently optimized thermal axes of runners and respective gates for high pressure die casting so as have a superior quality of the casted component.

Background of the Invention

[002] Casting is a manufacturing process to make complex shapes of metal components generally employed in mass production of such components. The casting is generally categorized a low pressure die casting (LPDC) and high pressure die casting (HPDC) wherein the molten metal flows in the mold through the feed runner system. The feed runner system includes a biscuit, a main runner, sub runners and in-gates designed in a manner to guide liquid metal during filling and solidification which takes place after intensification. The feed runner system plays a very important role for improving quality and reducing the losses of the final casted product.

[003] The conventional high pressure die-casting (HPDC) mold structure has a runner structure that includes a plurality of main runners, end runners, and in-gates. The mold structure has a moving plate and fixed plate and conventionally the runner feed system is incorporated in the moving plate of the mold so that after the solidification of the mold, the removal of the casted component becomes easy. In such kind of construction of the feed runner system, the thermal axis of the runners / sub-runners and the thermal axis of the in-gate in never in a single plane as the in-gate has the certain limitations of its thickness. Therefore, when the molten metal starts to solidify in the feed runner system, because of its nature of cooling in plates, it starts to solidify from the outer surface towards its inner core. Since, the thermal axes of the feed runner, gates and mold are in different planes, there are likely chances that the in-gate gets solidify quickly even well before the solidification of the mold due its limitation of thickness and thereby blocks the flow of molten metal in the mold beyond the gate. The mold being a high mass area solidify slowly and as the flow of molten metal is blocked from the in-gate, the mold is subjected to the shrinkage porosity which negatively impacts the final product quality of the casted component. Shrinkage porosity occurs as a result of volumetric shrinkage during solidification due to non-uniform cooling being the thermal axes of the mold and gate in different planes. The shrinkage porosity manifests the voids or internal discontinuities within the casting.

[004] The solidification process in high-pressure die casting (HPDC) begins when molten metal is injected into a cold mold causing it to rapidly cool as it comes into contact with the mold walls. As the metal cools, it solidifies from the outer surfaces towards in central axis creating a temperature gradient where the outer regions solidify first while the core of the mold and in-gate solidify in the last keeping the core in liquid state till the solidification reaches its central axis called as the thermal axis. Therefore, this central axis / thermal axis of the in-gate and the mold plays a crucial role in controlling the solidification behavior as it influences the cooling rate and the direction of the solidification front. If this thermal axis is not well managed in the mold and the in-gate, it leads to pre-mature solidification in the thinner sections, particularly the in-gates causing metal flow problems in the mold during the process of solidification of the said mold leading to shrinkage porosity and/or generation of voids in the casted component by the mold.

[005] Therefore, there is a long pending unmet need of intelligently optimizing the thermal axis of the in-gate of the feed runner system with that of the thermal axis of the runners or sub-runners of the runner feed system so as to have uniform cooling and thereby eliminating the issues of in-gate freezing, poor / restricted metal flow and shrinkage porosity in the mold and/or casted component by that mold. The present invention is intended to address the above mentioned limitations of the conventional feed runner system by providing an optimized thermal axis of the sub-runner and the in-gate of the feed runner system that significantly reduces the shrinkage porosity in high-pressure die casted automotive components and thereby provide superior quality and defect free casted components.

Objectives of the Present Invention

[006] The main object of the present invention is to provide an optimized feed runner system for high pressure die casting of automotive components.

[007] Another objective of the present invention is to provide casting feed runner system having a uniquely profiled in-gate and sub-runners employed therein to impart an improved filling and solidification of casting.

[008] Yet another objective of the present invention is to provide a casting feed runner system configured to produce automotive castings devoid of any internal defects, mechanical properties and visual defects.
[009] Yet, the object of the present invention is to delay the solidification of the in-gate of the feed runner system.

[0010] Another objective of the present invention is to provide optimized feed runner system for high pressure die casting configured to reduce shrinkage porosity in thick sections of the casted components.

[0011] Yet another objective of the present invention is to provide optimized feed runner system for high pressure die casting configured to improve overall flow of molten metal and thereby have the controlled solidification of the component being casted.

Brief Description of Drawings

[0012] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiment herein and advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0013] Figure 1 discloses the isometric view of the casting feed runner system as per the present invention.

[0014] Figure 2 describes the exploded view of the casting feed runner system of the present invention.

[0015] Figure 3a presents the top view of the casting feed runner system in accordance with the present invention, whereas, the Figure 3b shows the cut sectional view of the casting feed runner across A-A in accordance with the present invention
[0016] Figure 3c shows the front view of the casting feed runner system in accordance with the present invention

[0017] Figure 4a shows the thermal axis of at the sub-runner and in-gate of the conventional runner feed system, whereas the Figure 4b shows the thermal axis of the optimized feed runner system of the present invention.

[0018] Figure 5a shows the shrinkage porosity level in the mold by the conventional runner feed system, whereas the Figure 5b shows the shrinkage porosity level in the mold by the optimized feed runner system of the present invention.

Detailed Description of the Present Invention

[0019] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention. Referring to Figs. 1-3, the feed runner system (100) for high pressure die casting of the present invention is configured to have a biscuit (10), a main runner (20), a plurality of sub-runners (20A, 20B) and a plurality of in-gates (30A, 30B). The main runner (20) is a hollow body and at its one end is in communication with the base portion of the biscuit (10). The other end of the main runner (20) branches out into at least two longitudinal sub-runners (20A, 20B). The main runner (20) serves as the primary channel for molten metal directing the molten metal towards the sub-runners (20A, 20B) from the biscuit (10). The open end of each of the sub-runners (20A, 20B) is fitted with the in-gate (30A, 30B). Each of the in-gate (30A, 30B) is configured to have a trapezoidal cross section and each of the sub-runner (20A, 20B) is configured to have hexagonal cross sectional profile. The cross sectional area of the feed runner system (100) progressively decreases from main runner (20) to the sub runners (20A, 20B) and finally to the in-gate (30A, 30B) so as to have increased velocity of the molten metal while entering the same in the mold.

[0020] The biscuit (10) is configured to have a cylindrical profile and at its base is in communication with the main runner (20). The main runners (20) have at least two runners (20A and 20B) extending away laterally in angular direction from the central axis of the main runner (20) as shown in Fig. 3a. Each of the sub-runner (20A, 20B), while branching out from the main runner (20), maintains an angle (θ1, θ2) with the central longitudinal axis of the main runner (20). The angle (θ1) made by the sub-runner (20A) with the central longitudinal axis of the main runner (20) varies from 10 to 50 degree while the angle (θ2) made by the sub-runner (20B) with the central longitudinal axis of the main runner (20) varies from 10 to 40 degree. The main runner (20) along with the sub-runners (20A, 20B) are oriented with the biscuit (10) in such a way that the biscuit (10) is positioned along the X1-X1 plane and the sub-runners (20A, 20B) and the in-gate (30A, 30B) of the feed runner system (100) are positioned in the plane X2-X2. The plane X1-X1 lies in the fixed plate (FP) thereby positioning the biscuit (10) and the neck portion (20N) of the of the main runner (20) in the fixed plate.

[0021] The plane X2-X2 is configured to work as the parting plane for the fixed plate (FP) and the moving plate (MP). Since the plane X2-X2 is working as the parting plane and the sub-runners (20A, 20B) and the in-gate (30A, 30B) of the feed runner system (100) are positioned in the plane X2-X2, the said parting plane divides the sub-runners (20A, 20B) and the in-gates (30A, 30B) in two symmetric halves thereby creating the two cavities (20A1 and 20A2) for the sub-runner (20A), two cavities (20B1 and 20B2) for the sub-runner (20B), two cavities (30A1 and 30A2) for the in-gate (30A) and two cavities (30B1 and 30B2) for the in-gate (30B). The said cavities (20A1, 20B1, 30A1, 30B1) of the sub-runners (20A, 20B) and the in-gates (30A, 30B) are configured to be positioned in the moving plate (MP) whereas the cavities (20A2, 20B2, 30A2, 30B2) of the sub-runners (20A, 20B) and the in-gates (30A, 30B) are configured to be positioned in the fixed plate (FP). The cavities (20A1 and 20A2) of the sub-runner (20A) jointly forms the cavity (20C) of the sub-runner (20A) and similarly the cavities (20B1 and 20B2) of the sub-runner (20B) jointly forms the cavity (20C) of the sub-runner (20B). In the same way, the cavities (30A1 and 30A2) of the in-gate (30A) jointly forms the cavity (30C) of the in-gate (30A) and similarly the cavities (30B1 and 30B2) of the in-gate (30B) jointly forms the cavity (30C) of the in-gate (30B). This intelligent positioning of the cavities (20C) of the sub-runners (20A, 20B) and the cavities (30C) of the in-gates (30A, 30B) along the parting plane makes these cavities (20C, 30C) to spread symmetrically in the fixed plate (FP) and the moving plate (MP) leading to overlap the thermal axes of the sub-runners (20A, 20B) and the in-gates (30A, 30B) with said parting plane.

[0022] This unique and novel construction of the cavities (20C) and (30C) across the moving plate (MP) and the fixed plate (FP) makes the thermal axis of the sub-runners (20A, 20B) to coincide with the thermal axis of the in-gates (30A, 30B) which consequently leads to uniform solidification of the molten metal from the outer surface towards the thermal axis across the sub-runners (20A, 20B) and the in-gates (30A, 30B). This uniform solidification of the molten metal across the sub-runners (20A, 20B) and the in-gates (30A, 30B) maintains the continuous flow molten metal in the mold cavity till the mold gets completely solidify. This unique orientation of cavities of the sub-runners and the in-gates across the moving plate and fixed plates completely eliminates the issue of pre-mature solidification in the thinner sections, particularly the in-gates, eliminates the issues of metal flow problems in the mold during the process of solidification which consequently eliminates the generation of shrinkage porosity and/or voids in the casted component by the mold.

[0023] The cross-sectional profile of the sub runners (20A and 20B) is selected from any symmetric profile from the group of the circular, rectangular, elliptical, hexagonal and like. The cross-sectional profile of the in-gates (30A and 30B) is selected from any symmetric profile from the group of the circular, rectangular, elliptical, trapezoidal, hexagonal and like. However, in the preferred embodiment of the invention, the most preferred cross sectional profile of the sub-runners is selected from the hexagonal profile and the most preferred cross sectional profile of the in-gates is selected from trapezoidal profile as these profiles (hexagonal profile for sub-runners and trapezoidal profile for in-gates) provides the necessary ejection draft while removing the casting from the mold.

[0024] As far as the working of the present invention is concerned, the feed runner (100) having the optimized cross-sectional areas is injected with a molten aluminum alloy at the biscuit (10) with an average velocity of 3.5 to 4.5 m/s in a high pressure die casting system. The feed pressure of the molten aluminum alloy is set to be in the range of 815 to 917 kgf (i.e. 800 to 900 bar) and the temperature of the molten alloy is in the range of 600-800 °C resulting in complete and uniform filling of the mold cavity. When the mold cavity is completely filled, the molten metal alloy in the mold cavity starts to solidify gradually to form the casting. Till the complete solidification of the casting, the unique orientation of the sub-runners and in-gates across the parting plane of moving plate and fixed plate maintains the continuous flow of molten metal through in-gates so that the shrinkage porosity and the generation of voids in the casting is completely eliminated.
[0025] The automotive component casted by the present invention was tested in the laboratory through simulation analysis by using the dedicated test platform / software therefor as per the standards as shown in Figs. 4a to 5b. The Fig. 4b clearly shows that thermal axis of the sub-runners and the in-gates are co-planer resulting in extension of solidification time, particularly at the thinner sections of in-gates by 11% (i.e. from 5.4 seconds to 6 seconds). As a result, the in-gate remains liquid for longer, improving filling of thicker sections and preventing premature solidification. This intelligent optimization of the thermal axes of the sub-runners and the in-gates led to a substantial reduction in shrinkage porosity (more than 50%) as being depicted in Fig. 5b of the simulation test. Further, the said casted component was tested by radiography test as per the standard of American Society for Testing and Materials (ASTM E-2973) and the results were at par with that of the simulation test analysis all the parameters including the uniform solidification as the thinner sections and shrinkage porosity as well.

[0026] The feed runner system (100) of the present invention for high pressure die casting imparts following technical advantages that contributes to the advancement of technology leading to establishing the inventive step:
- It provides an improved and controlled solidification at the thinner sections thereby ensuring uniform and complete filling of the mold cavity.
- The uniform and complete filling of the mold cavity leads to avoid generation of shrinkage porosity and/or voids in the casted component.
- The optimized cross sectional profiles of the sub-runners and the in-gates provides the desired draft for ejection of the casting from the mold.
- It provides the casted product with improved finish and superior quality.
- It drastically reduces the rejection rate of the casted components.
- It produces the automotive castings devoid of any internal defects and visual and enhanced mechanical properties.
- The intelligent orientation of the in-gates across the parting plane efficiently delay the solidification time by 11%.

[0027] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the invention herein have been described in terms of a generalized form, those skilled in the art will recognize that the invention herein can be practiced with modification within the spirit and scope of the invention as described herein.
, Claims:We Claim:

1. A feed runner system (100) for high pressure die casting of automotive components comprises of a biscuit (10), a main runner (20), a plurality of sub-runners (20A, 20B), a plurality of in-gates (30A, 30B), a fixed plate (FP) and a moving plate (MP)
wherein,
- the main runner (20) at its one end is in communication with the base portion of the biscuit (10) and at its other end is configured to branch out into two longitudinal sub-runners (20A, 20B);
- the fixed plate (FP) and the moving plate (MP) are separated by the parting plane X2-X2;
- said main runner (20) along with the sub-runners (20A, 20B) are oriented with the biscuit (10) in such a way that the biscuit (10) is positioned along the X1-X1 plane and the sub-runners (20A, 20B) and the in-gate (30A, 30B) of the feed runner system (100) are positioned across the parting plane X2-X2;
- the biscuit (10) and the neck portion (20N) of the of the main runner (20) is configured to lie in the fixed plate (FP); and
- said parting plane X2-X2 is configured to divide the sub-runners (20A, 20B) and the in-gates (30A, 30B) in two symmetric halves thereby creating the two cavities (20A1 and 20A2) for the sub-runner (20A), two cavities (20B1 and 20B2) for the sub-runner (20B), two cavities (30A1 and 30A2) for the in-gate (30A) and two cavities (30B1 and 30B2) for the in-gate (30B).

2. The feed runner system (100) for high pressure die casting as claimed in claim 1, wherein
- the cavities (20A1, 20B1, 30A1, 30B1) of the sub-runners (20A, 20B) and the in-gates (30A, 30B) are configured to be positioned in the moving plate (MP);
- cavities (20A2, 20B2, 30A2, 30B2) of the sub-runners (20A, 20B) and the in-gates (30A, 30B) are configured to be positioned in the fixed plate (FP); and
- the positioning of the cavities (20C) of the sub-runners (20A, 20B) and the cavities (30C) of the in-gates (30A, 30B) along the parting plane is configured to make these cavities (20C, 30C) to spread symmetrically in the fixed plate (FP) and the moving plate (MP) leading to overlap the thermal axes of the sub-runners (20A, 20B) and the in-gates (30A, 30B) with said parting plane.

3. The feed runner system (100) for high pressure die casting as claimed in claim 2, wherein
- the cavities (20C) and (30C) across the moving plate (MP) and the fixed plate (FP) are configured to coincide the thermal axis of the sub-runners (20A, 20B) with the thermal axis of the in-gates (30A, 30B); and
- the orientation of cavities (20C, 30C) of the sub-runners (20A, 20B) and the in-gates (30A, 30B) across the moving plate (MP) and fixed plate (FP) is configured to eliminate the pre-mature solidification in the thinner sections and the generation of shrinkage porosity and/or voids in the casted component by the mold.

4. The feed runner system (100) for high pressure die casting as claimed in claim 3, wherein
- the cross-sectional profile of the sub runners (20A and 20B) is selected from hexagonal profile and the cross sectional profile of the in-gates (30A, 30B) is selected from trapezoidal profile; and
- these cross sectional profiles (hexagonal profile for sub-runners and trapezoidal profile for in-gates) are configured to impart ejection draft while removing the casting from the mold.

5. The feed runner system (100) for high pressure die casting as claimed in claim 4, wherein the process of casting an automotive component by employing said feed runner system (100) follows a set of sequential steps of injecting the molten aluminum alloy at the biscuit (10) followed by uniform filling of the mold cavity followed by gradual solidification of the casting in the mold cavity
wherein,
- the molten aluminum alloy is injected at the biscuit (10) with an average velocity of 3.5 to 4.5 m/s so as to pass into the mold cavity through the main runner (20), sub-runners (20A, 20B) and the in-gates (30A, 30B);
- the feed pressure of the molten aluminum alloy is in the range of 815 to 917 kgf (i.e. 800 to 900 bar); and
- the temperature of the molten alloy is in the range of 600-800 °C resulting in complete and uniform filling of the mold cavity.

6. The feed runner system (100) for high pressure die casting as claimed in claim 5, wherein
- the cross sectional area of the feed runner system (100) is configured to progressively decrease from the main runner (20) to the sub runners (20A, 20B) and finally to the in-gate (30A, 30B) so as to have increased velocity of the molten metal while entering the same in the mold.the open end of each of the sub-runners (20A, 20B) is fitted with the in-gate (30A, 30B);
- the main runner (20) has at least two runners (20A and 20B) extending away laterally in angular direction from the central axis of the main runner (20);
- each of the sub-runner (20A, 20B), while branching out from the main runner (20), is configured to make an angle (θ1, θ2) with the central longitudinal axis of the main runner (20); and
- the angle (θ1) made by the sub-runner (20A) with the central longitudinal axis of the main runner (20) varies from 10 to 50 degree while the angle (θ2) made by the sub-runner (20B) with the central longitudinal axis of the main runner (20) varies from 10 to 40 degree.

Dated this 25th day of Feb. 2025

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller of Patents,
The Patent Office, at Mumbai