INSERT MOLDING

Abstract

A method and apparatus involve positioning an insert within a cavity of a mold, heating an insert wall within the cavity of the mold, and casting a molten metal into the cavity adjacent the insert. A surface of the insert absorbs heat from the molten metal to melt and fuse to the molten metal.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application claims priority under 35 USC 119(e) from co-pending U.S. Provisional Patent Application Ser. No. 61/091,726 filed on Aug. 25, 2009 by Mark A. Baumgarten and entitled “INSERT MOLDING”, the full disclosure of which is hereby incorporated by reference.

BACKGROUND

Insert molding is a term used in the metal casting industry to describe the inclusion of a loose insert or inserts within the mold cavity which after the molten cast material has been introduced into the mold cavity and the cast geometry has solidified the insert or inserts and cast material have become one unit. Attaining a sufficiently strong bond between an insert or inserts and the cast geometry is difficult.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an insert molding system according to an example embodiment.

FIG. 2 is a schematic illustration of another embodiment of the insert molding system of FIG. 1 according to an example embodiment.

FIG. 3 is a schematic illustration of the insert molding system of FIG. 2 during insert molding.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

FIG. 1 is a schematic illustration of an insert molding system 20 according to an example embodiment. As will be described in more detail hereafter, insert molding system 20 provides a stronger and more reliable bond between an insert and the cast geometry about the insert. The enhanced junction between the insert and the cast geometry about the insert further enhances thermal conductivity between the insert and the cast geometry about the insert. In one embodiment, insert molding system 20 joins an insert and cast geometry of like or similar metals of non-ferrous metals using electrical current within a controlled atmosphere to create a metallurgical bond at the interface of the insert and the cast geometry eliminating the need for secondary joining processes. The metered combination of parameters used in creating the atmosphere within the closed cavity and the heat created by the introduction of electrical current to the metal insert “excite” the metallurgical structure of the insert, which at a surface level, fuse together with the molten cast material to form a bond. The introduction of a shielding gas (an inert gas such as argon) to the mold cavity as the alloy insert is being heated can minimize the formation of oxides that can have a negative impact on a preferred bond quality.

Insert molding system 20 generally includes mold 22, insert supports 24, insert heating system 26, gas introduction system 28, casting system 30, release agent system 31 and controller 32. Mold 22 comprises two or more structures forming a cavity 36 configured to receive an insert 38 (statically shown). Mold 22 is configured to be separated into its constituent parts to allow insertion of insert 38 and removal of insert 38 along with the cast material about insert 38. In one embodiment, mold 22 is formed from one or more metals or metal alloys, such as steel. Although illustrated as being generally rectangular, cavity 36 may have any of a variety of shapes or configurations depending upon the desired final shape or configuration of the product resulting from the insert molding.

Although insert 38 is illustrated as being generally rectangular in shape, insert 38 may also have any of a variety of different shapes, sizes and configurations. For example, in one embodiment, insert 38 may comprise a cylinder. Insert 38 is generally formed from one or more materials, wherein a surface of insert 38 is provided by a metal. For purposes of this disclosure, the term “metal” by itself includes individual metal elements as well as alloys of two or more metal elements. In one embodiment, insert 38 has surface portions formed from a first alloy (a combination of two or more metal elements), wherein the cast molten metal is an alloy from the same family (i.e. the same combination of two or more metal elements, albeit potentially having different percentages of the two or more metal elements).

In one embodiment, insert 38 may be additionally be pre-wetted or pre-fluxed along its surface to facilitate bonding with cast molten metals, such as metals not of the same alloy family. For example, in one embodiment, insert 38 may have copper surface portions which are pre-wetted or pre-fluxed to facilitate soldering or brazing of cast molten lead, zinc, copper or brass metals about insert 38.

In one embodiment, insert 38 may comprise a cylinder formed from aluminum. In other embodiments, insert 38 may have other configurations, including more complex shapes, and may be comprised of several components of other materials as an assembly including alloys of like or alloy as well as other metals or non-metallic materials. For example, insert 38 may have interior non-metal portions connected to or insulated from an exterior metal surface. Although system 20 is illustrated as using one insert 38, in other embodiments, system 20 may cast about multiple inserts within cavity 36.

Insert supports 24 comprise structures within mold cavity 36 and within mold 22 configured to support and retain insert 38 in place during the introduction of molten cast alloy into cavity 36. In one embodiment, such insert supports 24 may be joined, fastened, well become bonded or integrally formed as part of a singer unitary body with mold 22. In one embodiment, a portion of inserts 24 may extend into or through insert 38. In one particular embodiment, insert supports 24 may be omitted.

Insert heating system 26 comprises a system configured to heat insert 38 while insert 38 is within cavity 36 prior to casting the molten alloy about insert 38. Insert heating system 26 is configured to heat insert 38 such that the temperature of insert 38 is below the melting temperature of the alloy to make contact with the molten cast alloy. Although the temperature to which insert surface portion 40 is heated is below the melting temperature of the material of surface portion 40, the attained temperature is such that when surface portion 40 absorbs additional heat from multitasking 36 (when cavity 36 or mold 22 are heated) the molten cast metal introduced by casting system 30, the temperature of surface portion 40 rises to a temperature above the melting point of surface portion 40. As a result, surface portion 40 melts and fuses with the molten cast metal introduced by casting system 30 about insert 40. As a result, at least surface portion 40 of insert 38 becomes autogenous with the cast metal from casting system 30. This creates a stronger bond as well as enhanced thermal conductivity between insert 38 and the cast outer material. In one embodiment, one or multiple distinct surface portions of insert 38 may be heated by insert heating system 26. In yet another embodiment, substantially an entire outer surface of insert 38 may be heated to the initial temperature such that the entire outer surface of insert 38 melts and fuses with the molten cast alloy introduced by casting system 30.

As shown by FIG. 1, insert heating system 26 heats insert 38 while insert 38 is within cavity 36. As a result, insert 30 is heated within the closed volume provided by cavity 36 of mold 22. This closed volume creates a controllable environment that may tend to reduce the amount of oxygen coming into contact with the surface of insert 38 during heating. By reducing the amount of oxygen coming into contact with the surface of insert 38 during heating, oxidization of the surface of insert 38 is reduced to further enhance the quality of the bonding, “soldering” or “welding” of the surface of insert 38 to the cast alloy from casting system 30. In other words, any reduction of oxides formed on the surface of insert 38 will enhance the quality of the bond between the cast metal and insert 38.

According to one embodiment, insert heating system 26 includes an electrical heating system configured to apply an electrical current through and across insert 38. The metal of insert 38 has an electrical resistance such that insert 38 is heated by the electrical current. In one embodiment, insert heating system 26 includes an electric current source and a positive terminal and a negative terminal configured to contact insert 38 when insert 38 is received within cavity 36. Because electrical current is used to heat insert 38, insert 38 may be quickly and rapidly heated to a controlled temperature slightly below the melting temperature of the metal insert 38. As noted above, this temperature may be controlled such that additional heat absorbed by the molten cast metal from casting system 30 causes the like metal insert 38 to cross the melting threshold and fuse with the like molten cast metal of casting system 30. The rapid heating of insert 38 to required temperature and the timely introduction of molten cast metal from casting system 30 reduces the time that heated insert 38 is exposed to oxygen or other non-inert gases. This reduced exposure time reduces potential oxidation of the surface of the metal insert 38, further enhancing the quality of the bond between the metal insert 38 to the like cast metal.

In such an embodiment wherein insert heating system 26 comprises an electrical heating system configured to transmit an electrical current through and across insert 38, insert supports 24 are formed from an electrically insulating or electrically non-conductive material or materials. Such insulating insert supports 24 inhibit the electrical current from being conducted to mold 22 by insulating between insert 40 and mold 22. In one embodiment, the insulating supports 24 are formed from one or more non-conductive materials. In one embodiment, the insulating supports 24 comprise rings or discs between insert 38 and mold 22. In other embodiments, such electrical insulating insert supports 24 may have other shapes depending upon the shape of the one or more inserts 38 and the geometric configuration of the mold 22.

As noted above, because insert 38 is heated within a contained, controlled volume or cavity 36 of mold 22, insert 38 is less susceptible to oxidation or reaction with other non-inert gases. Gas introduction system 28 provides further shielding of insert 38 from oxidation during heating of insert 38. Gas introduction system 28 comprises a device to system configured to introduce a shielding gas or inert gas, such as argon, into cavity 36 during the heating of insert 38 by insert heating system 26. In one embodiment, system 20 is further configured to expel any oxygen from cavity 36 prior to the introduction of the shielding gas or inert gas and heating of the insert 38. For example, in one embodiment, system 20 may include a vacuum system 39 which not only draws oxgyen, air or other non-inert gases from cavity 36, but also draws the shielding gas or inert gas into cavity 36. After the air is drawn from cavity 36 to create a vacuum in cavity 36, a source or volume of inert gas is connected to cavity 36 such that the inert gas is sucked, drawn or pulled into cavity 36. The gas provided by gas introduction system 28 shields surfaces of insert 38 from interacting with oxygen during the heating of insert 38. In other embodiment, gas introduction system 28 may be omitted.

Casting system 30 comprises a system configured to introduce molten fluid material, such as a metal elements or alloys thereof, into cavity 36 adjacent to surface portion 40 of insert 38 or about insert 38. In one embodiment, casting system 30 comprises a die casting system. In another embodiment, casting system 30 may comprise a gravity casting system. As noted above, casting system 30 supplies the molten metal to cavity 36 at a sufficiently high temperature such that the heat added by the molten material heats at least surface portion 40 of insert 38 to a temperature above the melting temperature and melting threshold of the material of surface portion 40. As a result, insert 38 becomes autogenous with the molten metal upon cooling and solidification of the molten metal about insert 38.

Given the limitations of commonly used cavity coatings used to prevent cast metals from soldering or sticking to cavity surfaces, a release agent may be required as a supplement. Release agent system 31 comprises a system to apply a layer 44 of release agent along the interior of cavity 36. This layer of release agent facilitates separation of the cast part (and insert 40) from mold 22 upon separation or opening of mold 22.

In the example illustrated, release agent system 31 includes release agent charger 48 and release coating supply 50. Release agent charger 48 comprises a device configured to electrostatically charge release agent 50 so that it will be drawn to the grounded surfaces of mold 22. In one embodiment, release coating 50 comprises a powdered die lubricant (or release agent) configured to be attracted to grounded surfaces (similar to powder coating applications). As a result, the release agent 50 supplied by release agent system 31 adheres to those grounded surfaces of mold 22. Since insert supports 24 are electrically insulated or non-conductive, the release coating does not adhere to such supports 24.

In those embodiments in which insert heating system 26 is an electrical heating system that applies electrical current through and across insert 38 to heat insert 38, release agent system 31 coats the grounded surfaces of cavity 36 (other than insert 38) with electrostatically charged release agent 50. Release agent 50 is a particulate which when electrostatically charged adheres to the grounded cavity surfaces to which it is applied (as performed in the painting process know as powder-coating). Release agent system 31 is cycled while the mold is open and prior to the placing of the insert or inserts in cavity 36 (schematically shown). As insert supports 24 are made of non-conductive materials, the electrostatically charged particles of release agent 50 will not bond to insert supports 24. An air blow-off system 53 may be used to clear any excess release agent material from the mold surfaces prior to placing the insert or inserts in cavity 36. Preventing a conductive “bridge” between mold 22 and insert 38 minimizes downtime in production due to electrical faults. For example, many die release agents are water-born or in solution with other electrically conductive fluid materials. If the later agents are applied along the interior of mold 22 during the operation of insert molding system 20, electric current may be conducted from insert 38 to mold 22 faulting the system. In other embodiments, release agent system 31 may apply a release coating in other fashions without release agent charger 48. In other embodiments, release agent system 31 may be configured to introduce the electrostatically charged release agent 50 to the grounded surfaces of mold 22 while the mold is closed such as with the use of the LEOMACS SYSTEM commercially available from the TOSHIBA MACHINE CO., LTD, wherein an electrostatically charged dry die lubricant (or release agent) is drawn into the closed mold, by vacuum, from a port in the shot sleeve. In the later embodiment, the mold would have to be opened again to have any loose particulate about insert supports 24 cleared away by air blow-off system 53 prior to placing the insert or inserts in cavity 36. This additional opening and closing of the mold would increase cycle time but applying the dry die lubricant (or release agent) while the mold is closed is an environmentally cleaner process.

Controller 32 comprises one or more processing units configured to control the operation and timing of mold 22, insert heating system 26, gas introduction system 28, casting system 30 and release agent system 31. For purposes of this application, the term “processing unit” shall mean a presently developed or future developed processing unit that executes sequences of instructions contained in a memory. Execution of the sequences of instructions causes the processing unit to perform steps such as generating control signals. The instructions may be loaded in a random access memory (RAM) for execution by the processing unit from a read only memory (ROM), a mass storage device, or some other persistent storage. In other embodiments, hard wired circuitry may be used in place of or in combination with software instructions to implement the functions described. For example, controller 32 may be embodied as part of one or more application-specific integrated circuits (ASICs). Unless otherwise specifically noted, the controller is not limited to any specific combination of hardware circuitry and software, nor to any particular source for the instructions executed by the processing unit.

In the example illustrated, controller 32 generates control signals directing release agent charger 48 to electrostatically charge release agent 50. Controller 32 further generates control signals directing a supply of charged release agent 50 to be applied apply to the grounded interior surfaces of mold 22 forming release layer 44. In embodiments where system 20 omits release agent system 31, such steps by controller 32 may be omitted.

Upon application of release layer 44, controller 32 further generates control signals to close mold 22 after insertion of insert 38 between supports 24. Such insertion of insert 38 (or multiple inserts 38) may be automated (utilizing robotics) or performed manually. Controller 32 further generates control signals directing gas introduction system 28 to expel air from cavity 36 and to introduce an inert gas into cavity 36. Once the metered charge of inert gas has been provided about insert 38, controller 32 generates control signals directing insert heating system 26 to rapidly heat insert 38 to a temperature slightly below the melting temperature of the one or more materials along the exterior surface of insert 38. In one embodiment, controller 32 directs insert heating system 26 to apply an electrical current through and across insert 38. During such heating the inert gas atmosphere about insert 38 inhibits the formation of oxides on the surface of insert 38.

Once insert 38 or surfaces of insert 38 have been heated to a temperature just below the melting threshold of the metal insert 38, controller 32 generates control signals directing casting system 30 to introduce the molten cast metal into cavity 36, adjacent to surface portion 40 and about insert 38. Prior to contact of the molten cast metal with insert 38, controller 32 generates control signals terminating the application of electrical current to insert 38. In one embodiment, controller 32 may generate control signals terminating the application of current to insert 38 prior to the initiation of molten cast metal into cavity 36. In another embodiment, controller 32 may take into account the time required for the molten cast metal to contact insert 38 and may be configured to terminate the application of electrical current to insert 38 by system 26 immediately prior to such contact if deemed necessary to maximize bond quality, optimize cycle time, or other. In those embodiments in which insert heating system 26 does not employ electrical current to heat insert 38, such steps by controller 32 may be omitted.

FIGS. 2 and 3 illustrate insert molding system 120, a particular embodiment of system 20. Like system 20, system 120 provides a stronger and more reliable bond between an insert and the cast geometry about the insert. The enhanced junction between the insert and the cast geometry about the insert further enhances thermal conductivity between the insert and the cast geometry about the insert. In one embodiment, insert molding system 20 joins an insert and cast geometry of like or similar metals of non-ferrous metals using electrical current within a controlled atmosphere to create a metallurgical bond at the interface of the insert and the cast geometry eliminating the need for secondary joining processes. The metered combination of parameters used in creating the atmosphere within the closed cavity and the heat created by the introduction of electrical current to the alloy insert “excite” the metallurgical structure of the insert, which at a surface level, fuse together with the molten cast material to form a bond. The introduction of a shielding gas (an inert gas such as argon) to the mold cavity as the metal insert is being heated can minimize the formation of oxides that can have a negative impact on a preferred bond quality.

In the example illustrated, system 120 generally includes mold 122, insert supports 124, insert heating system 126, gas introduction system 128, casting system 130, release agent system 31 (shown in FIG. 1), ejection system 131 and controller 32 (shown in FIG. 1). Mold 122 comprises two or more structures forming a substantially closed or contained cavity 136 configured to receive an insert 138 (schematically shown). Mold 122 is configured to be separated into its constituent parts to allow insertion of insert 138 and removal of insert 138 along with the cast metal about insert 138. As shown by FIG. 2, mold 122 includes a vent 123. Vent 123 allows air or other non-inert gases to be pushed or discharged from cavity 136. At the same time, vent 123 is sufficiently small or appropriately spaced from a location at which molten metal is introduced by casting system 130 such that the molten metal does not flow through vent 123 during casting of the molten metal. In one embodiment, vent 123 may alternatively be connected to a vacuum system, such as vacuum system 39 (shown and described above with respect to system 20). Although mold 122 additionally includes other various openings, such openings are closed off by other components such as with electrodes, ejection pins or the like. In one embodiment, mold 122 is formed from one or more metals or metal alloys, such as steel. Although illustrated as being generally rectangular, cavity 136 may have any of a variety of shapes or configurations depending upon the desired final shape or configuration of the product resulting from the insert molding.

Although insert 138 is illustrated as a cylinder, in other embodiments, insert 138 may have any of a variety of different shapes, sizes and configurations. Insert 138 is generally formed from one or more materials, wherein a surface of insert 138 is provided by one or more metals. In one embodiment, insert 138 has surface portions formed from a first alloy (a combination of two or more metal elements), wherein the cast molten metal is an alloy from the same family (i.e. the same combination of two or more metal elements, albeit potentially having different percentages of the two or more metal elements). In one embodiment, insert 138 may comprise a cylinder formed from aluminum. In other embodiments, insert 138 may have other configurations, including more complex shapes, and may be comprised of several components of other materials as an assembly including alloys of like or alloy as well as other metals or non-metallic materials. For example, insert 138 may have interior non-metal portions connected to or insulated from an exterior metal surface. Although system 120 is illustrated as using one insert 38, in other embodiments, system 120 may cast about multiple inserts within cavity 136.

Insert supports 124 comprise structures within mold cavity 136 and within mold 122 configured to support and retain insert 138 in place during the introduction of molten cast alloy into cavity 36. In one embodiment, such insert supports 124 may be joined, fastened, well become bonded or integrally formed as part of a singer unitary body with mold 122. In one embodiment, a portion of inserts 24 may extend into or through insert 138. In the particular example illustrated, insert supports 124 extend on opposite axial ends of insert 138 and further extend through insert 138. In some embodiments, insert supports 124 may be omitted.

Insert heating system 126 comprises a system configured to heat insert 138 while insert 138 is within cavity 136 prior to casting the molten metal about insert 138. Insert heating system 126 is configured to heat insert 138 such that the temperature of insert 138 is below the melting temperature of the alloy to make contact with the molten cast alloy. Although the temperature to which insert surface portion 140 is heated is below the melting temperature of the material of surface portion 140, the attained temperature is such that when surface portion 140 absorbs additional heat from cavity 136 (when cavity 136 or mold 122 are heated) the molten cast metal introduced by casting system 130, the temperature of the surface portion 140 of insert 138 rises to a temperature above the melting point of surface portion 140. As a result, surface portion 140 melts and fuses with the molten cast metal introduced by casting system 130 about insert 138. As a result, at least surface portion 140 of insert 138 becomes autogenous with the cast metal from casting system 130. This creates a stronger bond as well as enhanced thermal conductivity between insert 38 and the cast outer material. In one embodiment, one or multiple distinct surface portions of insert 138 may be heated by insert heating system 126. In yet another embodiment, substantially an entire outer surface of insert 138 may be heated to the initial temperature such that the entire outer surface of insert 138 melts and fuses with the molten cast alloy introduced by casting system 130.

As shown by FIG. 1, insert heating system 126 heats insert 38 while insert 138 is within cavity 136. As a result, insert 130 is heated within the closed volume provided by cavity 136 of mold 122. This closed volume creates a controllable environment that may tend to reduce the amount of oxygen coming into contact with the surface of insert 138 during heating. By reducing the amount of oxygen coming into contact with the surface of insert 138 during heating, oxidization of the surface of insert 138 is reduced to further enhance the quality of the bonding, “soldering” or “welding” of the surface of insert 138 to the cast alloy from casting system 130. In other words, any reduction of oxides formed on the surface of insert 138 will enhance the quality of the bond between the cast metal and insert 138.

In the example illustrated, insert heating system 126 includes an electrical heating system configured to apply an electrical current through and across insert 138. Insert heating system 126 includes a negative electrode 141 and a positive electrode 143. Electrodes 141 and 143 apply an electrical current through and across insert 138. The metal of insert 138 has an electrical resistance such that insert 138 is heated by the electrical current. Because electrical current is used to heat insert 138, insert 138 may be quickly and rapidly heated to a controlled temperature slightly below the melting temperature of the metal insert 138. As noted above, this temperature may be controlled such that additional heat absorbed by the molten cast metal from casting system 130 causes the surface of metal insert 138 to cross the melting threshold and fuse with the like molten cast metal of casting system 130. The rapid heating of insert 138 to the required temperature and the timely introduction of molten cast metal from casting system 130 reduces the time that heated insert 138 is exposed to oxygen or other non-inert gases. This reduced exposure time reduces potential oxidation of the surface of the metal insert 138, further enhancing the quality of the bond between the metal insert 138 to the like cast metal.

In such an embodiment wherein insert heating system 126 comprises an electrical heating system configured to transmit an electrical current through and across insert 138, insert supports 24 are formed from an electrically insulating or electrically non-conductive material or materials. Such insulating insert supports 124 inhibit the electrical current from being conducted to mold 122 by insulating between insert 138 and mold 122. In one embodiment, the insulating supports 124 are formed from one or more non-conductive materials. In one embodiment, the insulating supports 124 comprise rings or discs between insert 138 and mold 122. In other embodiments, such electrical insulating insert supports 124 may have other shapes depending upon the shape of the one or more inserts 38 and the geometric configuration of the mold 122.

As noted above, because insert 138 is heated within a contained, controlled volume or cavity 136 of mold 122, insert 38 is less susceptible to oxidation or reaction with other non-inert gases. Gas introduction system 128 provides further shielding of insert 138 from oxidation during heating of insert 138. Gas introduction system 128 comprises a device or system configured to introduce a shielding gas or inert gas, such as argon, into cavity 136 prior to or during the heating of insert 138 by insert heating system 126. In one embodiment, system 120 is further configured to expel any oxygen from cavity 36 prior to the introduction of the shielding gas or inert gas and heating of the insert 138.

In the example illustrated, gas introduction system 128 includes an inert gas injection port 145 through which inert gas may be introduced into chamber 136. In the example illustrated, gas introduction system or 128 further includes an additional or alternative inert gas injection port 147 through which inert gas may be induced into cavity 136. As will be described hereafter, the regulation of flow of inert gas through port 147 is partially controlled by the ejection system 131. In other embodiments, one of ports 145 and 147 may be omitted. In yet other embodiments, inert gas may be introduced by gas introduction system 128 in other fashions.

Casting system 130 comprises a system configured to introduce molten fluid material, such as a metal elements or alloys thereof, into cavity 136 adjacent to surface portion 140 of insert 138 or about insert 138. In one embodiment, casting system 130 comprises a die casting system. As shown by FIG. 2, casting system 130 includes a shot sleeve 151, a shot rod 153 connected to a plunger tip 154. Shot sleeve 151 comprises a tube or sleeve having a pour hole 155 through which molten metal 158 may be supplied to into sleeve 151. Shot rod 153 and its plunger tip 154 are connected to a powered actuator (not shown) which drives the molten metal 158 within sleeve 151 through a gating and runner system 160 into cavity 136 about insert 138.

In another embodiment, casting system 30 may comprise a gravity casting system. As noted above, casting system 130 supplies the molten metal to cavity 136 at a sufficiently high temperature such that the heat added by the molten material heats at least surface portion 140 of insert 138 to a temperature above the melting temperature and melting threshold of the material of surface portion 140. As a result, insert 138 becomes autogenous with the molten metal upon cooling and solidification of the molten metal about insert 138.

Given the limitations of commonly used cavity coatings used to prevent cast metals from soldering or sticking to cavity surfaces, a release agent may be required as a supplement. Release agent system 31 (shown in FIG. 1) comprises a system to apply a layer 44 of release agent along the interior of cavity 136. This layer of release agent facilitates separation of the cast part (and insert 40) from mold 122 upon separation or opening of mold 122.

In the example illustrated, release agent system 31 (schematically shown in FIG. 1) includes release agent charger 48 and release coating supply 50. Release agent charger 48 comprises a device configured to electrostatically charge release agent 50 so that it will be drawn to the grounded surfaces of cavity 136. In one embodiment, release coating 50 comprises a powdered dry die lubricant (or release agent) configured to be attracted to grounded surfaces (similar to powder coating applications). As a result, the release agent 50 supplied by release agent system 31 adheres to those grounded surfaces of mold 122. Since insert supports 124 are electrically insulated or non-conductive, the release coating does not adhere to such supports 124.

In those embodiments in which insert heating system 126 is an electrical heating system that applies electrical current through and across insert 138 to heat insert 138, release agent system 31 coats grounded surfaces of cavity 136 (other than insert 38) with electrostatically charged release agent 50. Release agent 50 is a particulate which when electrostatically charged adheres to the grounded surfaces of the cavity to which it is applied (as performed in the painting process know as powder-coating). Release agent system 31 is cycled while the mold is open and prior to the placing of the insert or inserts in cavity 36 (schematically shown). As insert supports 124 are made of non-conductive materials, the charged particles of release agent 50 will not bond to insert supports 124. An air blow-off system 53 may be used to clear any excess release agent material from the mold surfaces prior to placing the insert or inserts in cavity 136. Preventing a conductive “bridge” between mold 122 and insert 138 minimizes downtime in production due to electrical faults. For example, many die release agents are water-born or in solution with other electrically conductive fluid materials. If the later agents are applied along the interior of mold 122 during the operation of insert molding system 20, electric current may be conducted from insert 138 to mold 122 faulting the system. In other embodiments, release agent system 31 may be configured to introduce the electrostatically charged release agent 50 to the grounded surfaces of cavity 136 while the mold is closed such as with the use of “The New LEOMACS System” wherein an electrostatically charged dry die lubricant (or release agent) is drawn into the closed mold, by vacuum, from a port in the shot sleeve. In the later embodiment, the mold would have to be opened again to have any loose particulate about insert supports 124 cleared away by air blow-off system 53 prior to placing the insert or inserts in cavity 136. This additional opening and closing of the mold would increase cycle time but applying the dry die lubricant (or release agent) while the mold is closed is an environmentally cleaner process.

Ejection system 131 comprises a device or mechanism configured to eject the completed product from cavity 136 when mold 122 is opened. In the example illustrated, ejection system 131 includes an ejection pin 163 connected to an actuator (not shown). As the actuator advances ejector pin 163, and possible others, the cast geometry and the insert 138 bonded thereto, are ejected from cavity 136. In one embodiment, ejection pin 163 also serves as a valve for opening and closing inert gas injection port 147.

Controller 32 (schematically shown in FIG. 1) comprises one or more processing units configured to control the operation and timing of mold 122, insert heating system 126, gas introduction system 128, casting system 130, release agent system 31 and ejection system 131. In the example illustrated, controller 32 generates control signals directing a supply of electrostatically charged release agent 50 to be applied apply to the grounded interior surfaces of mold 122 forming release layer 144 (shown in FIG. 1). In embodiments where system 120 omits release agent system 31, such steps by controller 32 may be omitted.

FIGS. 2 and 3 illustrate the insert molding process. As shown by FIG. 2, upon application of release layer 144, controller 32 further generates control signals to close mold 122 after insertion of insert 138 between supports 124. Such insertion of insert 138 (or multiple inserts 138) may be automated (utilizing robotics) or performed manually. Controller 32 further generates control signals directing are causing the introduction of molten metal 158 through pour hole 155 into shot sleeve 151.

During or prior to the introduction of the molten metal 158 into shot sleeve 151, controller 32 also generates control signals directing gas introduction system 128 to supply inert gas through port 145 into sleeve 151. As inert gas is pushed into cavity 36, existing air within cavity 136 is pushed out of cavity 136 through vent 123. During the time period that the inert gas has surrounded insert 138, controller 32 generates control signals causing insert heating system 126 to heat insert 138. As noted above, in the example illustrated, this is achieved by supplying an electrical current through and across insert 138 using electrodes 141 and 143. During such heating, molten metal 158 has not yet reached insert 138. Prior to the molten metal 158 reaching insert 138, controller 32 generates control signals terminating the heating of insert 138 are cutting off the supply of electrical current to insert 138.

As further shown by FIG. 2, in some of embodiments, inert gas may also be introduced through port 147. During such introduction, ejection pin 163 is withdrawn from port 147, opening port 147. Gas introduction system 128 pushes inert gas through port 147 into cavity 136. The introduction of inert gas through port 147 may be used independently or in combination with the introduction of inert gas through port 145.

As shown by FIG. 3, after insert 138 has been sufficiently heated in the presence of the inert gas, controller 32 generates control signals directing an actuator (not shown) to drive shot rod 153 and its plunger tip 154 to push molten metal 158 through gating and runner system 160 into cavity 136 about insert 138. Movement of plunger tip 154 blocks or interrupts the flow of additional inert gas through port 145 into cavity 136. At this time controller 32 also generates control signals to close the valve allowing the introduction of inert gas through port 147. During such injection or casting of molten metal 158 into cavity 136, controller 32 also generates control signals directing an actuator (not shown) to move the ejection pin 163 to the position shown in FIG. 3 in which ejection pin 163 closes off port 147, interrupting the flow of inert gas through port 147. In particular, during the injection of molten metal 158 into cavity 136, the tip of the ejector pin 163 is adjacent to cavity 136. The heat introduced by the molten metal 158 is partially absorbed by the exterior portions of insert 138 to raise the temperature of such surface portions of insert 138 above the melting threshold of such surface portions. As a result, the surface portions of insert 138 fuse to the molten metal.

Once the molten metal has sufficiently solidified and/or cooled, controller 32 generates control signals directing actuator 52 (shown in FIG. 1) to open mold 122. After the mold has opened controller 32 generates a control signal directing actuator 52 to advance ejection system 131 (not shown) along with ejector pin 163 to eject the completed part from cavity 136 of system 120.

Although the present disclosure has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.

Claims

1. A method comprising:

positioning an insert within a cavity of a mold;

heating the insert wall within the cavity of the mold; and

casting a molten metal into the cavity adjacent the insert, wherein a surface of the insert absorbs heat from the molten metal to melt and fuse to the molten metal.

2. The method of claim 1 further comprising providing an inert gas adjacent the surface during heating of the insert.

3. The method of claim 2, wherein the inert gas is provided through a port and wherein the method further comprises moving an ejection pin from a first position closing the port to a second position opening the port.

4. The method of claim 1, wherein the surface of the insert and the molten metal are from a same family of alloys.

5. The method of claim 1 further comprising applying electrical current to the insert to heat the insert within the mold cavity.

6. The method of claim 5 further comprising providing an inert gas adjacent the surface during heating of the insert.

7. The method of claim 5 further comprising an electrically insulating the insert from the mold.

8. The method of claim 5 further comprising terminating the application of electrical current to the insert immediately preceding casting of the molten metal into the cavity.

9. The method of claim 1 further comprising applying a release layer to the mold.

10. The method of claim 9, wherein the release layer is configured to be attracted to the mold due to an electrical charge applied to the mold.

11. An insert molding system comprising:

a mold having a cavity configured to receive an insert;

an insert heating system configured to heat at least a surface of the insert while the insert is within the cavity to a temperature below a melting temperature of the surface; and

a casting system configured to cast a molten metal into the cavity adjacent the surface of the insert, the molten metal supplying heat to the surface of the insert to raise a temperature of the surface to above the melting temperature of the surface.

12. The system of claim 11, wherein the insert heating system comprises a electrical heating system configured to apply an electrical current across the insert.

13. The system of claim 12 further comprising at least one electrically insulating member configured to extend between the insert and the mold when the insert is within the mold.

14. The system of claim 13, wherein the at least one electrically insulating member comprises an electrically non-conductive mold component.

15. The system of claim 13, wherein the at least one electrically insulating member includes one or more ceramic materials.

16. The system of claim 12 further comprising a gas introduction system configured to provide an inert gas adjacent to the surface of the insert within the cavity during heating of the insert.

17. The system of claim 16, wherein the gas introduction system provides the inert gas through a shot sleeve of the casting system.

18. The system of claim 12 further comprising a controller configured to generate control signals directing the electrical heating system to terminate the application electric current across the insert prior to the fluid material from the casting system contacting the surface of the insert.

19. The system of claim 11 further comprising a gas introduction system configured to provide an inert gas adjacent to the surface of the insert within the cavity during heating of the insert.

20. The system of claim 19, wherein the gas introduction system introduces the inert gas through a shot sleeve of the casting system.