Improved investment casting process for automatic sprue cutting with metal filled by gravity

Abstract

Improved investment casting process with metal poured under gravity for automatic sprue cutting presents a novel process aimed at eliminating the need for cutting by draining the main feeder metal before solidification. Traditional casting processes require the manual or machine cutting of cast pieces from the central feeder, adding complexity, time, and cost to production while introducing the risk of defects. Present method utilizes existing investment casting equipment, applying vacuum / air pressure & drain sprue [103b] to facilitate drainage of the central feeder [103], allowing for automatic disconnection of cast pieces[103c] before solidification. The disclosed process, for the investment casting industry, reduces production time, costs. The steps involved in the proposed method and introduces a supplementary device [102] for collecting canter rod metal.

Description

[0001] TITLE OF THE INVENTION:

[0002] IMPROVED INVESTMENT CASTING PROCESS FOR AUTOMATIC SPRUE CUTTING WITH METAL FILLED BY GRAVITY

[0003] TECHNICAL FIELD OF AN INVENTION:

[0004] The present invention belongs to the field of investment casting, and provides casting pieces separation method which is used for realizing casting piece separation is done by investment casting process itself.

[0005] BACKGROUND ART:

[0006] Within the domain of investment casting, continuous efforts are made to enhance efficiency and reduce production time. One notable improvement on the traditional investment casting method lies in streamlining post-casting operations, particularly the removal of cast pieces from the runner or sprue after solidification.

[0007] Following the pouring of molten metal into the ceramic mould, the mould are allowed to sit undisturbed to facilitate the cooling and solidification of the metal. This critical phase ensures that the molten metal takes the shape of the mould and transforms into the final casting.

[0008] Once the metal has solidified, the ceramic mould are carefully broken apart to reveal the castings encased within the shell material. This shell removal process typically involves various techniques such as hammer knockout, vibration, water jet blasting and steel grit blasting. These methods effectively dislodge the ceramic shell material from the solidified metal castings.

[0009] After the shell material has been removed, the finished cast parts separated from the gating and runner system. This is usually accomplished through cutting or sawing, ensuring that the castings are free from any residual attachments or excess material. The cut-off stage marks the final step in the investment casting process, producing individual cast parts ready for further finishing and assembly as required by design.

[0010] Traditionally, cut-off step has been labour-intensive and time-consuming, often requiring manual and or machine cutting and or sawing to separate the cast pieces from the runner or sprue. Present invention provides a supplementary device also called as “collection base for centre rod metal”; and a “method for automated separation of cast pieces in casting processes”, by integrating casting process given by present invention in investment casting process, manufacturers can achieve notable reductions in production time and costs. Moreover, the enhanced efficiency and precision offered by present invention contribute to improved overall productivity.

[0011] In proposed improvement, we are focusing on enhancing the metal pouring stage of the process by introducing a drain sprue and supplementary molten metal collection device, allowing for a smoother flow of molten metal under gravity. Present innovation aims to revolutionize the investment casting process by significantly reducing the time and effort required for critical tasks such as separating the cast pieces by sprue cutting. By integrating advanced techniques for automated cast piece separation and rapid verification of metals, we anticipate substantial improvements in efficiency and productivity. These enhancements not only save time and resources ultimately contributing to increased competitiveness in investment casting operations.

[0012] The present invention provides improved investment casting process with metal poured under gravity for separation of cast piece, the present invention introduces supplementary device that can be easily attached to existing setups without major modifications. By automating the separation process and utilizing gravity force, particularly in lost wax investment casting, the present invention enhances productivity in applications such as metal manufacturing.

[0013] DISCLOSURE OF THE INVENTION

[0014] A method for, investment casting for automatic sprue cutting with metal filled by gravity, comprising steps in it;

[0015] (a) Produce wax or resin patterns;

[0016] (b) Attach multiple wax patterns to a sprue, forming a cluster, wherein each pattern is connected to sprue in angular manner with inclined gating, improving upon said sprue, the drain sprue [103b] is attached at the base of said sprue [103d];

[0017] (c) Dip or coat the wax tree in a ceramic slurry to build a thick and durable investment shell around the wax patterns;

[0018] (d) Heat the investment shell in a kiln or furnace, causing the wax patterns to melt and flow out of the mould, leaving behind a precise cavity that mirrors the original metal design; (e) Heat the investment shell to a higher temperature to remove any remaining waxy residue, moisture, ensuring a clean and solid mould for casting;

[0019] (f) Place the prepared investment mould in a vacuum or centrifugal casting machine. Pour molten metal, such as precious metals, into the mould under gravity pressure, filling the cavity and taking on the shape and details of the original wax pattern;

[0020] (g) Allow the filled mould to cool and solidify. Once cooled, break away the investment shell to reveal the separate metal casting pieces without sprue and drain sprue attachment;

[0021] An investment casting method in which improvement comprising; a wax tree with drain sprue attachment [103b]; and a supplementary metal collection device

[0102] ; wherein, the flask mould

[0103] contains a cavity formed from investment casting, comprising a wax tree and an extension of a central feeder [103d] called as drain sprue [103b]

[0022] Present invention encompasses advancements in investment casting processes aimed at reducing the time required for separating cast pieces. This invention provides improved investment casting process with metal poured under gravity / centrifugal force for automatic sprue cutting to reduce the cast pieces separation time & cost, invention provide the supplementary device also called as collection base for centre rod metal which can be easily integrated on the existing setup.

[0023] BRIEF DESCRIPTION OF FIGURES:

[0024] Figure 1: illustrates 3D sectional dissembled view of casting setup

[0100]

[0025] Figure 2: illustrates the 3D sectional view of supplementary device

[0102]

[0026] Figure 3: illustrates the 2D sectional view of Supplementary device

[0102]

[0027] Figure 4: illustrates the 3D sectional assembled view of casting schematic setup

[0100]

[0028] Figure 5: illustrates the 2D sectional view of assembled investment casting schematic setup

[0100]

[0029] Figure 6: illustrates the 3D dissembled view of investment casting schematic setup

[0100]

[0030] Figure 7: illustrates the 3D sectional view of assembled investment casting schematic setup

[0100] BEST MODE(S) FOR CARRYING OUT THE INVENTION

[0031] The method of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] In an embodiment, as shown in FIG. 1-7, the investment casting where drain sprue [103 b] is provided, drains sprue is a small opening and extension given to the central feeder [103d], When the molten metal is poured inside the basin [103 a] the metal will flows basin to the in- gates arrangements [103b’], the in-gates are arranged in the angular manner to get benefitted by gravity force hence called inclined gating [103b’]. The molten metal flows to in-gates to the cast piece cavity [103c],

[0033] Figure 2, depicts sectional view of a supplementary device

[0102] , the supplementary device is consisting the separator [102’], not shown in figure. The supplementary device containing the separator (not shown in figure) which is provided at the middle of the supplementary device by which the excess molten metal is collected at two separate sections in the supplementary device.

[0034] Figure 1 further depicts the pneumatic piston rod [101a] which is connected to supplementary device through connector rod [101b].The pneumatic cylinder is generally provided in the jewellery manufacturing where the plate (not shown in figure) is provided, that plate is connected by means of connector rod [101b] and serves as the seat for the supplementary device to rest on it. In present invention, we are providing the supplementary device which rests on that plate and above the supplementary device the flask can rest easily.

[0035] Figure 6, depicts the 3D dissembled view of investment casting schematic setup

[0101] , as the vacuum is applied circumferentially to the cylindrical flask

[0101] and hence the slurry will provide porous openings by which the entrapped air will flow outside the perforated flask

[0103] as the molten metal enters the perforated flask. The quality of cast pieces obtained is same as obtained from the traditional method of investment casting.

[0036] Investment casting flask

[0103] as shown in figure 5 consisting of basin [103a], Central feeder

[0103] and Drain sprue [103b] attachment. The inclined gating [103b’] will connects the central feeder to the Cast pieces [103c], once the molten metal fills the centre feeder

[0103] and the cast cavities [103c], the drain sprue [103b] opening for the molten metal which will flow and collected at the supplementary device

[0102] provided below the perforated cylindrical flask

[0103] , The supplementary device containing the separator (not shown in figure) which is provided at the middle of the supplementary device by which the excess molten metal is collected at two separate sections in the supplementary device. Here the time of cooling of molten metal to get the cast pieces is reduces as we are separating the extra molten metal by means of sprue [103b], The metal velocities here are also streamlined and there is no chances of having the casting defects. The cast pieces are having the same and similar quality which is produces by the ongoing lost wax casting method.

[0037] A method for automated separation of cast pieces in casting processes comprising of:

[0038] (a) Produce wax or resin patterns using hand carving or 3D printing technology, ensuring they accurately replicate the desired metal design, including intricate details;

[0039] (b) Attach multiple wax patterns to a sprue, forming a cluster where each pattern is connected to sprue in angular manner with inclined gating, the Drain sprue [103b] is attached at the base of sprue [103d];

[0040] (c) Dip or coat the wax tree in a ceramic slurry multiple times, allowing each layer to dry before applying the next. Repeat this process to build a thick and durable investment shell around the wax patterns;

[0041] (d) (d)Heat the investment shell in a kiln or furnace, causing the wax patterns to melt and flow out of the mould, leaving behind a precise cavity that mirrors the original metal design;

[0042] (e) Heat the investment shell to a higher temperature to remove any remaining waxy residue, moisture, or impurities, ensuring a clean and solid mould for casting;

[0043] (f) Place the prepared investment mould in a vacuum or centrifugal casting machine. Pour molten metal, such as precious metals, into the mould under gravity pressure only, filling the cavity and taking on the shape and details of the original wax pattern;

[0044] (g) Allow the filled mould to cool and solidify, ensuring the metal solidifies into the desired shape. Once cooled, break away the investment shell to reveal the separate metal casting pieces without sprue attachment. In one of the embodiment showing an investment casting apparatus in which the casting mould depicted in which improvement of the mould cavity comprising; a cavity form from metal tree with drain sprue attachment [103b]; and a supplementary metal collection device

[0102] arranged below the perforated flask

[0103] ; Wherein, the perforated flask mould

[0103] contains a cavity formed from investment casting, comprising a wax tree and an extension of a central feeder [103 d] called as drain sprue [103b],

[0045] In conventional casting procedures, the separation of cast pieces from the central feeder typically requires either manual cutting with cutter & the use of cutting machinery. This additional step not only extends production time and costs but also introduces the possibility of errors or imperfections in the cast pieces. Existing solutions in casting processes rely on cutting techniques to detach cast pieces from the central feeder. These methods often involve manual labour or the utilization of specialized cutting equipment. However, the cutting process adds complexity and expense to the casting procedure. Manual cutting can be time-consuming and labour-intensive, leading to delays in production. On the other hand, machine cutting necessitates extra equipment and maintenance, resulting in increased capital expenditure and operational costs. Furthermore, both manual and machine cutting methods carry the risk of defects or damage to the cast pieces. The proposed innovation aims to eliminate the necessity for cutting cast pieces by draining the main feeder metal before it solidifies. This process involves utilizing existing investment casting equipment, where molten metal flows from the top and fills separately heated cavities at a specific temperature. Vacuum is applied to the outer periphery of the investment casting flask, facilitating flow from the top to the mould cavities to the bottom supplementary device. As the drain sprue is having very minimum diameter the metal will get the time to fill all the casting mould cavities also the peripheral vacuum is applies and due to that the metal will get sucked inside the mould cavities. The metal present in the centre rod is removed by means of the drain sprue, hence as a result, the parts in the cavities automatically disconnect from the central feeder before solidification occurs. This method is designed for application in the investment casting process and similar processes where applicable.

[0046] The method disclosed in the present invention comprises several steps, including pouring molten metal from crucible, filling individual cavities, and applying peripheral vacuum to the flask. Additionally, a new step involves collecting the centre rod metal at bottom in the supplementary metal collection device.

[0047] The supplementary device provided by the present invention, as depicted in Figure 2, consists of a seat to rest the flask and the hollow cavity for liquid metal collection. The central feeder rod diameter is larger than drain sprue; attached below. Central wax sprue has an extension of wax with a smaller diameter is called as drain sprue. The supplementary device is constructed from steel. During the casting solidification, the centre rod metal is collected in the supplementary device cavity.

[0048] WORKING OF THE DEVICE

[0049] Example of casting process adapted by present invention:

[0050] Example 1 : Utilize hand-carved or 3D printed wax or resin patterns to accurately replicate intricate metal designs. Attach multiple wax patterns to sprue, forming a cluster with each pattern connected to a central pathway for molten metal flow, here sprue contains the sprue with drain sprue connection. Make sure that drain sprue is not providing any surface for pattern attachment. Drain sprue is provided for only molten metal flow from basin to the supplementary device. Dip the Tree in a Debubblizer (A debubblizer is a surface tension chemical compound that is used in certain industrial processes to minimize air bubbles when casting a mold or impression). Coat the “wax tree with drain sprue” with a ceramic slurry, building a durable investment shell around the patterns through multiple layers. Heat the investment shell to melt and burn off remove the wax patterns, leaving behind precise cavities and the drain pathway that mirror the original designs. Heat the investment shell to eliminate any remaining waxy residue, moisture, or impurities, ensuring a clean the mould for casting. Place the prepared investment mould in a vacuum / centrifugal casting machine. Pour molten metal. Allow the filled mould to cool and solidify. Once cooled, break away the investment shell to reveal the metal castings pieces without sprue attachment. Hence we are getting the separated cast pieces. Clean, polish, and refine the castings to remove imperfections and excess metal. Since the metal patterns are free from centre rod metal attachment, the cut-out step is eliminated, saving time. Example 2: Produce wax or resin paterns using hand carving or 3D printing technology, ensuring they accurately replicate the desired jewellery design, including intricate details. Attach multiple wax patterns to sprue, forming a cluster where each patern is connected to a central pathway for molten metal flow. This cluster is called as wax tree. The drain sprue need to be attached at the bottom of sprue end to facilitate the molten metal flow. Dip the Tree in a Debubblizer (A debubblizer is a surface tension chemical compound that is used in certain industrial processes to minimize air bubbles when casting a mold or impression). Embed the wax tree, Dip or coat the wax tree in a ceramic slurry multiple times, allowing each layer to dry before applying the next. Repeat this process to build a thick and durable investment shell around the wax patterns. Heat the investment shell in a kiln or furnace, causing the wax patterns to melt and flow out of the mould, leaving behind a precise cavity that mirrors the metal design. Further heat the investment shell to a higher temperature to remove any remaining waxy residue, moisture, or impurities, ensuring a clean and mould for casting. Place the prepared investment mould in a vacuum or centrifugal casting machine. Pour or inject molten metal, such as gold, silver, or platinum, into the mould under gravity only, filling the cavity and taking on the shape and details of the original wax pattern. This new method reduces the need for applying pressure on feeder rod metal. Allow the filled mould to cool and solidify, ensuring the metal solidifies into the desired shape. Once cooled, break away the investment shell to reveal the metal casting pieces. Perform additional processes such as stone seting, engraving, or plating to enhance the final appearance of the jewellery piece.

[0051] While gravity casting certainly has its advantages, being already in practice widely & known, cost- effective and reliable. The prior gravity casting does not provide the cast piece separation hence the present invention is more advantageous over the prior methods. In present method, vacuum is applied to the flask, and the mould is preheated to a specific temperature prior temperature called burnout temperature. When the molten metal is poured into the flask, the vacuum draws the metal into the cavity. Additional insights from the client regarding the specific benefits and adjustments of this method are encouraged.

[0052] The present invention method has been thoroughly verified in jewellery casting for small batch productions, showcasing its reliability and efficacy. Its applicability, however, extends far beyond jewellery making, encompassing various ferrous or nonferrous metal industries. In the automotive sector, it can produce engine components with intricate geometries. As well as in the medical and dental fields, present invention contributes to the fabrication of precise devices in healthcare. Also its utilization extends to industrial applications, offering efficiency and precision in diverse manufacturing processes.

[0053] Investment casting’s versatility spans across various industries, offering precision, customization, and design flexibility to meet diverse needs and applications.

[0054] As we know that cost of goods sold (COGS) is deducted from revenues (sales) in order to calculate gross profit and gross margin. Higher COGS results in lower margins. By using this new method of casting COGS will get reduced as “the amount includes the cost of the materials and labour directly used to create the good is reduced”.

[0055] Companies must manage their COGS to ensure higher profits. If a company can reduce its COGS through better deals with suppliers or through more efficiency in the production process, it can be more profitable.

[0056] The present invention enables method for centre rod and feeder sprue design in casting processes.

[0057] Provided method is useful in jewellery casting to make the jewellery casting with less input metal investment. The sprue cutting operations and manual cost involved in sprue cutting is reduces if this process is adopted instead of traditional method, sprue cutting machines requires monthly maintenance; by adopting this novel process will help to reduce this associated costs.

[0058] INDUSTRIAL APPLICABILITY

[0059] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0060] Furthermore, this invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments or examples set forth herein. Rather, these embodiments or examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout the description of the figures or diagrams. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected or coupled" to another clement, there are no intervening elements present. Furthermore, "connected" or "coupled" as used herein may include connected or coupled. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0061] The aim of this specification is to describe the invention without limiting the invention to any one embodiment or specific collection of features. Person skilled in the relevant art may realize the variations from the specific embodiments that will nonetheless fall within the scope of the invention.

[0062] It may be appreciated that various other modifications and changes may be made to the embodiment described without departing from the spirit and scope of the invention.

Claims

WE CLAIM:

1. A method for, investment casting for automatic sprue cutting with metal filled by gravity, comprising steps in it;(a) Produce wax or resin patterns;(b) Attach multiple wax patterns to a sprue, forming a cluster, wherein each pattern is connected to centre sprue in angular manner with inclined gating, improving upon said spruce, the drain sprue [103b] is attached at the base of said centre spruce;(c) Dip or coat the wax tree in a ceramic slurry to build a thick and durable investment shell around the wax patterns;(d) Heat the investment shell in a kiln or furnace, causing the wax patterns to melt and flow out of the mould, leaving behind a precise cavity that mirrors the original metal design;(e) Heat the investment shell to a higher temperature to remove any remaining waxy residue, moisture, ensuring a clean and solid mould for casting;(f) Place the prepared investment mould in a vacuum or centrifugal casting machine. Pour molten metal, such as precious metals, into the mould under gravity, filling the cavity and taking on the shape and details of the original wax pattern.(g) Allow the filled mould to cool and solidify. Once cooled, break away the investment shell to reveal the separate metal casting pieces without sprue and drain sprue attachment.

2. An investment casting method in which improvement comprising; a wax tree with drain sprue attachment [103b]; and a supplementary metal collection device [102]; wherein, the flask mould [103] contains a cavity formed from investment casting, comprising a wax tree and an extension of a central feeder [103d] called as drain sprue [103b]

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