Core release spray application method and apparatus

Abstract

A method for forming a core includes the step of providing a corebox defining in a closed configuration thereof a closed internal core-forming cavity and providing at least one external opening through the corebox into said cavity in the closed configuration (902). A core release substance is applied through the opening directly onto at least one surface of the closed core-forming cavity with the corebox in the closed configuration (904). A forming material is added to the cavity (906) followed by an addition of a core bonding agent (908). A core that has formed in said closed core-forming cavity is allowed to dry and removed from the cavity (910).

Description

FIELD OF THE INVENTION

This invention relates to casting methods, including but not limited methods used to form cores for use in casting molds.

BACKGROUND OF THE INVENTION

A typical sand casting operation includes a series of steps or processes for forming and preparing a mold for casting. A model or pattern for a component to be cast is created and used to form a mold and various internal cores, as is known in the art. The same model is typically used to create a large number of molds. The molds and cores created are typically made by compaction of a granular material such as sand that has a high resistance to heat. The sand used to form cores is further bonded to retain its shape by an appropriate material, for example, an epoxy or phenolic material.

Tooling for forming cores, or coreboxes, are typically assembled from at least two, typically three or four, separate pieces to facilitate handling and forming of the cores. In a previous process, a forming operation for internal cores begins with at least two exterior pieces of tooling dies that form a cavity between them when assembled. The tooling dies are laid open and sprayed with a core release spray. Non core forming surfaces of the tooling dies are washed or blown clean to remove core release overspray, and the tooling is closed. Subsequent to closing the tooling, sand and a bonding agent are added in the cavity to form the core, and the tooling is opened to eject the completed core. The tooling is cleaned once more using compressed air or an appropriate washing agent, and the process is repeated.

A major disadvantage of the traditional spraying application for the core release substance is that much of the core releases substance is wasted. Spraying onto the tooling uses more of the substance than is necessary for the core contact areas of the tooling, due to overspray, and yet is not effective in ensuring that the core release substance will adequately cover the intricate core forming surfaces of the tooling dies. Moreover, open spraying of the core release substance onto the tooling dies releases particles of the substance to the atmosphere.

Accordingly, there is a need for a more effective and economical method of applying a core release substance onto core forming tooling dies in a corebox.

SUMMARY OF THE INVENTION

A core-forming apparatus includes a multipiece corebox defining in a closed configuration thereof an internal cavity with at least one opening into the internal cavity in the closed configuration and an externally-supplied spray head for dispensing a core release substance. The spray head is disposed inside the corebox through the opening to spray the core release substance directly onto a surface of the internal cavity while the corebox is closed, thereby avoiding overspray onto non-core-forming surfaces of the corebox.

A method for forming a core includes the steps of providing a multi-piece corebox defining in a closed configuration thereof a closed internal core-forming cavity and providing an external opening through the corebox into said cavity in the closed configuration. With the corebox in the closed configuration, a core release substance is applied through the opening directly onto at least one surface of the closed core-forming cavity. A core forming material is then added into the cavity and a core bonding agent in injected into the cavity. Finally, a core that has formed in the cavity is allowed to dry and is subsequently removed.

Another method for forming a core for use in a casting operation includes the step of connecting a tooling mold having a closed configuration defining a closed internal cavity and an opening from the closed internal cavity through the tooling mold to a first shuttle. The internal cavity is filled with sand through the opening and the opening through the tooling mold is then connected to a second shuttle. The sand that has filled the cavity is injected with a bonding agent and allowed to cure and form a casting core. The tooling mold is opened, and the formed casting core is ejected and removed from the tooling mold. The tooling mold is closed and then the opening through the tooling is connected to a third shuttle. With the tooling mold closed, the cavity is sprayed with a core release substance through a spray head extending through the opening that is connected on the third shuttle, and the core release substance is allowed to dry and be ready for the next core forming operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of prior art tooling dies used for forming cores used in casting operations.

FIG. 2 is an illustration of the tooling dies of FIG. 1 placed on a conveyor system and undergoing a core release substance coating process.

FIGS. 3A-3D are illustrations of successive steps employed in the prior art process to assemble a corebox, fill a cavity with sand, add a bonding agent to the cavity, and open the corebox to eject and remove a newly formed core.

FIG. 4 is an illustration of spraying a closed corebox with a core release substance in accordance with the invention.

FIGS. 5A-5C are illustrations of successive steps employed to fill a cavity of the previously-coated corebox cavity of FIG. 4 with sand, add a bonding agent, and open the corebox to eject and remove a newly formed core, in accordance with the invention.

FIG. 6 is an illustration of an alternate embodiment of a corebox undergoing a deposition process of a core release substance having a spray head inserted into a mold cavity through more than one opening in accordance with the invention.

FIG. 7 is an illustration of a closed corebox undergoing an automated deposition process of a core release substance having a spray head inserted into a mold cavity in accordance with the invention.

FIG. 8 is an illustration of a closed corebox undergoing a manual deposition process of a core release substance having a spray head inserted into a mold cavity in accordance with the invention.

FIG. 9 is a flowchart for a method of forming a core in accordance with the invention.

FIG. 10 is a flowchart for a method of forming a core for use in a casting operation in accordance with the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

The following describes an apparatus for and method of creating a sand core for use in casting a component. In prior processes, a core release substance, used to facilitate removal of a core from the tooling used to form it, is sprayed into a tooling cavity while the tooling is in an open position. A typical process for creating a core 100 is illustrated in FIG. 1. A first tooling die 102 may have a core forming surface 104, a die contact surface 106, and an exterior surface 108. A passage 110 connects the core-forming surface 104 with the exterior surface 108. A second tooling die 112 is constructed to mate with the first tooling die 102, and has a core-forming surface 114, a die contact surface 116, and an exterior surface 118.

In a typical prior core-forming operation, a process begins with spraying a core release substance onto the dies 102 and 112, as shown in FIG. 2. A conveyor system 200 may be used to carry the dies 102 and 112 to a spray station 201. When in the spray station 201, a spray head 202 that is either manually or electronically controlled sprays a layer 204 of a core release substance 206 onto the internal surfaces 104 and 114, as well as on the contact surfaces 106 and 116, and even on some of the external surfaces 108 and 118 due to overspray. The core release substance or material 206 is intended to prevent bonding of the core material to the internal surfaces 104 and 114 of the dies 102 and 112.

Although some quantity of the substance 206 is deposited onto the surfaces 104 and 114 that lie between the mold pieces 103 and 120 when assembled, the layer 204 that has been deposited onto surfaces 106 and 116 is removed, typically by scraping or blowing the excess material off, to ensure that the dies 102 and 112 fit together well for the subsequent core forming operation. This additional scraping or blowing operation is time consuming and also releases particles into the air. Moreover, the sprayer 202 may not adequately deposit enough of the core release substance 206 into deep crevasses and hard-to-reach areas and depressions of the dies 102 and 112.

The coated dies 102 and 112 are assembled as shown in FIG. 3A to form an internal cavity 302. At this point in the process, the dies 102 and 112 are ready to form the core 100 in the cavity 302. A first shuttle 304 connects to the opening 110 and deposits a core forming material 306, as shown in FIG. 3B. A shuttle as used in this process denotes a mechanically or manually manipulated machine element that is capable of operably connecting to the opening 110. When the material 306 has filled the cavity 302, a second shuttle 308, which may connect to opening 110 or another opening, injects a bonding agent 310 into the cavity 302 as shown in FIG. 3C. The bonding agent 310, advantageously in gaseous form, bonds the material 306 to form the core 100. When the core 100 is sufficiently bonded, the shuttle 308 is removed, the dies 102 and 112 open, and the core 100 is ejected as shown in FIG. 3D. After completion of a cleaning process of the dies 102 and 112 that removes left over core material that may have adhered to the surfaces 104 and 114, the process is repeated. This typical process has a few disadvantages. First, the process of creation of the layer 204 onto the dies 102 and 112 requires an additional cleaning operation to remove the core release material 206 that is deposited due to overspray onto unnecessary surfaces. Second, the spray station 201 may release particles of the 206 material into the air thus increasing an airborne particle content of air at a facility where it is used. Third, the core release material that is not sprayed in the core-forming surfaces 104 and 114 is wasted and accordingly increases the processing costs and processing time. These and other disadvantages may be rectified by use of an improved die preparation process, as follows.

A first die 402 and a second die 404 may be assembled before application of a core release material, as shown in FIG. 4. The assembled dies 402 and 404 yield a corebox 406 having a closed configuration which has a closed internal cavity 408 and at least one opening or port 410 from the internal cavity 408 to the exterior of the corebox 406. A first shuttle 412 connects to the opening 410 and deposits a core release material 406 onto at least a portion of an internal surface 414 of the cavity 408. The first shuttle 412 may further include a spray head 405 may extend into the internal cavity to provide more uniform coating of the cavity surfaces. Examples of suitable core release materials include a substance marketed under “Zip slip 121S,” supplied by Ashland Corporation, and “Cobra 15 N,” supplied by the Hill & Griffith Corporation. A layer 416 of core release material 406 is created around the cavity 408. The corebox 406 is now ready to form a core 500.

The process of forming the core 500 following the internal deposition of the layer 416 onto the cavity 408 while the dies 402 and 404 are assembled is similar to a typical core forming process. A second shuttle 502 connects to the cavity opening 410, or another opening if desired, to deposit a core forming material 506, as shown in FIG. 5A. When the material 506 has filled the cavity 408, a second shuttle 508, which may connect to opening 410 or another opening, injects a bonding agent 510 into the cavity 408 as shown in FIG. 5B. The bonding agent 510, advantageously in gaseous form, bonds the material 506 to form the core 500. When the core 500 is sufficiently bonded, the shuttle 508 is removed, the dies 402 and 404 open, and the core 500 is ejected as shown in FIG. 5C. The process may be repeated to form additional cores.

Application of a core release substance within an internal cavity of a corebox in a closed configuration is also advantageous for coreboxes having intricate internal cavities or internal core features, as shown in FIG. 6. In this embodiment, a corebox 600, when assembled out of two or more individual tooling dies, includes an internal cavity 602, a first opening 604 and a second opening 606. A first internal feature 608 is positioned within the cavity 602 and may be connected to a second internal feature 610. Both internal features 608 and 610 may be connected to each other, and may be connected to an internal wall or surface 612 of the internal cavity 602. The corebox 600 may be made by assembly of numerous dies similar to the assembly process discussed above.

In the application of a core release substance 614, a spray head 616, supported by an advantageously flexible arm 618, may be inserted into the cavity 602 through the opening 604. A layer 620 of a core release substance 614 is advantageously sprayed onto a portion of the surface 612 adjacent to the spray head 616. The spray head 616 is subsequently removed to allow the layer 620 to dry. The spray head 616 may then be inserted through the opening 606, shown in the alternative location denoted by dashed lines, to continue spraying the layer 620 onto another portion of the surface 612. The spray head may continue entering the cavity 602 as many times and through as many openings as is required to cover the surface 612 substantially, or more than 90%, with the layer 620.

Each of the openings 604 and/or 606 may be openings formed especially to allow the spray head 616 to enter into the cavity 602, but may advantageously be openings formed in the corebox 600 for other reasons, such as to insert a spray nozzle to dispense core forming material, to supply a bonding agent or resin to cure the core material, to help eject a formed core from the cavity 602, and so forth. Furthermore, the flexible arm 618 may be configured for manual or mechanical control of motion, and may advantageously be agile enough to maneuver the spray head 616 thorough intricate passages that lead from the outside of the corebox 600 into the internal cavity 602. The flexible 618 arm may advantageously be capable of axial and rotational motion along three axes.

In the embodiment shown in FIG. 7, a corebox 700 having an internal cavity 701 may be carried through a manufacturing facility on a conveyor system 702 in an assembled state up to a spray station 704. The station 704 may include a base unit 706 connected to an electronic controller 708. The electronic controller 708 may also be connected to various sensors (not shown) or other controllers (not shown) that may relay information to the controller 708, such as, a position of the corebox 700 and other coreboxes (not shown) on the conveyor system 702, and so forth. The controller 708 may be pre-programmed with a location of an opening 710 on the corebox 700 that provides access to the internal cavity 701. The controller 708 may control and guide a plurality or arms or, in general, a shuttle or control mechanism 712. The control mechanism 712 may be capable of supplying a substance to a spray head 714 located at a distal end of the mechanism 712. The controller 708 may guide the spray head 714 through the opening 710 and into the cavity 701. Alternatively, the spray head 714 may be adapted to attach to the opening 710 and have at least one spray nozzle (not shown) attached thereon that is aimed toward the cavity 701. The controller 708 may then initiate spraying a core release substance 716 into the cavity 701. In the case where more than one opening are available and/or required for satisfactory coverage of the cavity 701 with the substance 716, the controller 708 may retract the mechanism 712 from the opening 710 and re-insert in into another opening (not shown) as required.

In the embodiment shown in FIG. 8, a corebox 800 having an internal cavity 801 with an opening 810 is carried in an assembled state up to a spray station 804 by a conveyor system 802. The station 804 may include a base unit 806 controlled by an operator 808. The operator 808 may be capable of halting the motion of the corebox 800 within a specified location along the conveyor system 802, adjacent to the station 804. The operator 808 may control and guide a shuttle or manual mechanism 812. The mechanism 812 may be capable of supplying a substance to a spray head 814 located at a distal end of the mechanism 812. The operator 808 may guide the spray head 814 through the opening 810 and into the cavity 801. The operator 808 may then initiate spraying a core release substance 816 into the cavity 801. In the case where more than one opening is available and/or required for satisfactory coverage of the cavity 801 with the substance 816, the operator 808 may retract the mechanism 812 from the opening 810 and re-insert in into another opening (not shown) as required.

A flowchart for a method of forming a core for use in a mold for casting a component is shown in FIG. 9. A multi-piece corebox is provided at step 902 that defines, in a closed configuration thereof, a closed internal core-forming cavity and an external opening through the corebox. A core release substance is applied through the opening directly onto at least one surface of the closed core-forming cavity, with the corebox still in the closed configuration, at step 904. A core forming material, for example sand, is added into the closed core-forming cavity at step 906. A core bonding agent is added to the closed core-forming cavity at step 908 to bond core forming material that has completely filled the cavity. A core that has formed in the closed core-forming cavity is allowed to dry and is then removed from the corebox at step 910. An optional washing of the corebox when in an open configuration may be used to clean leftover core forming material. One example of a core wash substance is known as “4783” and is supplied by the Delta HA Corporation that can be used to advantageously clean the mold piece and provide a smoother casting surface.

The core release substance that is applied through the opening directly onto at least one surface of the closed core-forming cavity, with the corebox still in the closed configuration, may advantageously be applied by spraying the core release substance from a spray head that is inserted within the internal core cavity through the opening, and/or a spray head that attaches to the opening and has, for example, a nozzle that is aimed toward the cavity. The spray head may be carried by a shuttle, or in this case, an automated piece of a machine that is arranged to automatically deploy and attach to the corebox at an appropriate location that aligns the spray head with the opening.

A flowchart for a method of forming cores for use in a casting operation is shown in FIG. 10. A tooling mold having a closed configuration that defines a closed internal cavity and an opening from the closed internal cavity through the tooling mold is connected to a first shuttle at step 1002. The closed internal cavity is filled with sand through the opening at step 1004. The tooling mold is connected to a second shuttle, and the sand in the closed internal cavity is injected with a bonding agent at step 1006. The sand in the closed internal cavity is allowed to cure and form a casting core at step 1008. The tooling mold is opened, and the formed core is ejected and removed from the tooling mold at step 1010. The tooling mold is closed at step 1012. The closed tooling mold is connected to a third shuttle at the opening at step 1014. The closed internal cavity is sprayed with a core release substance through a spray head that is connected on the third shuttle and extends through the opening at step 1016. The core release substance is allowed to dry at step 1018, and the tooling mold is now ready to be used for forming another core.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. An apparatus comprising:

a corebox for forming a core for a cast component having a closed configuration and defining a closed internal cavity having at least one opening operatively connecting the cavity with an exterior surface of the corebox;

a spray head for dispensing a core release substance disposed in operative engagement with said opening;

wherein the spray head is disposed to spray the core release substance onto at least one internal surface of the internal cavity with the corebox in the closed configuration.

2. The apparatus of claim 1, wherein the corebox includes at least two mold pieces, and wherein each of the at least two mold pieces are connected to each other to form said closed configuration.

3. The apparatus of claim 1, wherein the internal cavity has a second opening, and wherein the spray head enters the second opening to spray an additional quantity of the core release substance.

4. The apparatus of claim 1, wherein the at least one opening is a passage through which a core forming material is added to the corebox.

5. The apparatus of claim 1, wherein the spray head has at least one spray nozzle attached thereon, and wherein the at least one spray nozzle has an orifice through which the core release substance is sprayed.

6. The apparatus of claim 1, wherein the spray head has freedom of axial motion and freedom of rotation along three axes.

7. The apparatus of claim 1, further comprising an electronic controller, wherein at least one of a motion and a rotation of the spray head is controlled by the electronic controller.

8. The apparatus of claim 1, wherein the spray head is controlled manually by an operator.

9. The apparatus of claim 1, further comprising a shuttle that is connectable to the core box, wherein the spray head is disposed on the shuttle.

10. The apparatus of claim 1 wherein the spray head is disposed during operation within the cavity through the opening to spray the core release substance therewithin.

11. A method for forming a core, comprising the steps of:

providing a multipiece corebox defining in a closed configuration thereof a closed internal core-forming cavity and providing an external opening through the corebox into said cavity;

applying a core release substance through the opening directly onto at least one surface of the closed core-forming cavity with the corebox in the closed configuration;

adding a core forming material into said closed core-forming cavity;

adding a core bonding agent to said closed core-forming cavity; and

allowing a core that has formed in said closed core-forming cavity to dry and removing the core from the corebox.

12. The method of claim 11, wherein the application step is accomplished by spraying the core release substance from a spray head that is inserted into said cavity through the opening.

13. The method of claim 11, wherein the application step is accomplished by spraying the core release substance from a spray head that is connected onto said corebox at the opening.

14. The method of claim 12, further comprising the step of cleaning residual core forming material from the corebox after the previously formed core has been removed.

15. The method of claim 11, wherein the step of application of the core release substance is accomplished by accelerating the core release substance through at least one spray nozzle, wherein the at least one spray nozzle is disposed on the spray head.

16. The method of claim 11, wherein the core forming material is sand.

17. A method for forming a core for use in a casting operation, comprising the steps of:

connecting a tooling mold having a closed configuration defining a closed internal cavity and an opening from the closed internal cavity through the tooling mold to a first shuttle;

filling the closed internal cavity with sand through the opening;

connecting said tooling mold to a second shuttle and injecting said sand in said closed internal cavity with a bonding agent;

allowing said sand in said closed internal cavity to cure and form a casting core;

opening said tooling mold, ejecting, and removing said casting core from said tooling mold;

closing said tooling mold;

connecting said tooling mold to a third shuttle at said opening;

spraying said closed internal cavity with a core release substance through a spray head extending through the opening that is connected on the third shuttle; and

allowing core release substance to dry.

18. The method of claim 17, further comprising the step of removing loose sand away from said tooling mold when said tooling mold is open and after said casting core has been removed.

19. The method of claim 17, further comprising the step of disconnecting said third shuttle from said tooling mold and reconnecting said third shuttle to said tooling mold at a second opening.

20. The method of claim 17, wherein said tooling mold includes a plurality of cavities, each connected to at least one of a plurality of corresponding openings.