The present invention generally relates to the use of additive manufacturing techniques for creating molds and pattern parts for use in the casting of die components for use on die assemblies, as well as for making molds for die shoes.
Die components, such as trim steels, scrap cutters, flange steels, form steels, pierce inserts, trim inserts, button block inserts, and the like, are components of a stamping die assembly that form and cut away excess sheet steel from a vehicle part, such as a hood, door panel, or other like part being formed. There are any number of die components used per stamping die assembly, each one having a unique configuration and function. Thus, it is impractical to cast multiple die components using traditional sand casting methods, which involve tooling up a mold pattern to form a sand core from which the die component is cast. The present invention provides techniques to create a pattern part or a mold core package that can later be used in the casting process to cast one or more die components having a near net-shape of the finished part. In this way, the present invention provides a cast part which greatly reduces the amount of finishing work that needs to be performed on the part after being cast. Further, the present invention provides a method which involves less stock material to cast the near net-shape die component part.
The common method for producing die components is through an investment casting process, which involves a pattern maker gluing Styrofoam® pieces together in an approximate shape of the die component and then machining that Styrofoam® into the desired shape and size of the die component to be cast. Recently, this technology has been referred to as subtractive manufacturing and is also used with metallic blocks or other such billets that are machined down to the approximate shape of a die component. This machining process lacks the precision needed to cast a near net-shape of the die component. Thus, extra machining stock, as much as 10 mm, is left on the subtractively manufactured pattern part and the resulting casting. This extra casting stock must be machined using a lengthy process, which involves scanning the object and creating a CNC program that is based on the actual shape of the desired part. Having the extra machining stock on the final cast part requires multiple rough machining steps, especially when a cutting edge is desired on the die component. The multiple rough machine steps are necessary because the extra stock on the cast part often exceeds the penetration depth of the CNC machine, such that the extra stock must first be removed through any number of rough cut operations. The part must be hardened between rough machining processes and, finally, finish machined. The present invention eliminates several of the post-casting steps involved in making a finished die component.
According to one aspect of the present invention, a method of making a pattern part for use in casting a die component includes the steps of (a) depositing a thin layer of polymeric powder on a build platform and (b) selectively applying a solvent to particular regions of the thin layer of polymeric powder to bind the polymeric powder in said regions to define a cross-section of the pattern part. Steps (a) and (b) are repeated to produce a completed pattern part having a configuration of the die component to be cast. The pattern part is then coated with a slurry to form a shell surrounding the pattern part. The shell is then heated to harden the shell and vaporize the pattern part to create a shell comprising a negative image of the pattern part. A molten material is cast into the shell to form the die component.
According to another aspect of the present invention, a method of making a die component includes the steps of forming a mold core package using an additive manufacturing process, wherein the mold core package comprises a negative image of the die component to be cast. A molten material is cast into the mold core package, and the molten material is cooled to form the die component having a near net configuration of the mold core package within an accuracy range of plus or minus 1 mm to 5 mm.
According to yet another aspect of the present invention, a method of making a plurality of sand mold packages for use in casting die components includes the steps of printing a plurality of sand mold packages using an additive 3D printer wherein the plurality of sand mold packages comprises one or more die component configurations. Select sand mold packages from the plurality of sand mold packages are nested into a casting structure having runners in communication with each select sand mold package. A molten material is cast into the casting structure to fill each select sand mold package using the runners. The molten material is then cooled to form the unique die components having a near net configuration of each select sand mold package.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.
In the drawings:
For the purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in
The present invention eliminates many steps in the process of making a die component due to its accuracy and automation, which saves a great deal of time, materials, and costs in the manufacturing of a die component. Using additive manufacturing or additive fabrication techniques, the accuracy and automation of the present invention allows for the elimination of several post-cast processing steps to create the desired die components. According to embodiments of the present invention, sacrificial dies and sacrificial pattern parts are provided through various additive manufacturing processes that manufacture the molds or pattern parts three-dimensionally one layer at a time. Sacrificial materials used in the additive manufacturing processes of the present invention include epoxies, sand, sand-ceramic mixes, powdered metals, plastic resins, and the like. In the additive manufacturing processes of the present invention, a three-dimensional (3D) mold or pattern part is assembled by producing and sequentially stacking thin cross-sectional layers of the desired mold or part as generated in an additive manufacturing machine. To create a three-dimensional part used in the methods of the present invention, a CAD program or other like computer-aided drawing software is used to create design data of the mold or pattern part to be formed.
Types of additive manufacturing processes known in the art include stereolithography apparatuses (SLA), 3D sandprinting, and other three-dimensional printers, ink jet printers that bond layers of powder material, plastic compositions using a bonding solvent, metallic based powders using a laser sintering device, and many other such processes known in the art that will be appreciated by one skilled in the art. Thus, any such process may be suitable in conjunction with the present invention in creating a sacrificial pattern part of a die component or a sacrificial mold for a die component without departing from the spirit of the present invention.
One such rapid manufacturing process includes a sandprinting process which will now be described. This method is commenced by first acquiring a 3D data design using a CAD model program to create a sand mold package for a die component which, as exemplified below, will be in the form of a trim steel die component. It is contemplated, however, that any such die component can be created using this process. First a 3D image of the pattern part is created using a CAD program. The pattern part or model is then subtracted from a 3D CAD model to create a sand mold package design. The resulting 3D model of the sand mold package is then produced using the techniques as described with reference to
Referring now to
As used throughout this disclosure, the term “mold core packages” will refer to sand printed or otherwise formed molds that are ready for casting of a molten material. The term “molds” will refer to a component of the mold core package and the term “cores” refers to an insert that is inserted into a mold for displacing molten material as cast into the mold core package. Thus, the combination of molds and cores creates a mold core package for casting. For purposes of the description of the formation of mold core packages or sand mold packages using the three-dimensional printing process discussed below, a sand mold package 110 as shown in
The printing device 42 includes a hopper 46 at a deposition trough 48, which lays a thin layer of activated fine particulate 50, such as silica sand, ceramic-sand mixes, etc., inside the print area 44. The particulate 50 may be of any size, including 0.002 mm to 2 mm in diameter. The printing device 42 also includes a binder deposition device or binder dispenser 52. As disclosed in detail below, the binder dispenser 52 sprays a thin layer of binder or binding agent 16 in a configuration or pattern 80 of a single layer of a desired sand mold package or sand core package. Repetition of the layering of sand and spraying of binding agent 16 by the binder dispenser 52 on the fine particulate 50 results in the production of a three-dimensional sand mold package or sand core package from a plurality of the stacked particulate layers. The 3D sand mold package is manufactured additively over a length of time sufficient to print each thin layer of the fine particulate 50 in succession, such that each layer of bound particulate is further bound to adjacent layers, to form a completed sand mold package. Each thin layer of the completed sand mold package measures approximately 0.28 mm. The sand mold package will ultimately be used as a sacrificial mold to fabricate a die component, such as the trim steel 120 as shown in
With specific reference to
It is contemplated that CAD, or any other form of 3D modeling software, can be used to provide sufficient information for the 3D printing device 42 to form the desired sand mold packages 100. Prior to activation of the 3D printing device 42, a predetermined quantity of the fine particulates 50 is dumped into the hopper 46 by a particulate spout 62, along with an activation coating or activator 70 supplied by an activator spout 72. Although the illustrated embodiment uses a fine sand, such as the fine particulate 50, as noted above, the fine particulate 50 may include any of a variety of materials or combinations thereof suitable for the additive manufacturing techniques disclosed herein. The fine particulates 50 are mixed in the hopper 46 with the activator 70. The mixture of fine particulates 50 and activator 70 may be mixed by an agitator 74 or other known mixing device such that the fine particulates 50 become thoroughly mixed and activated. After the fine particulates 50 and activator 70 have been thoroughly mixed, the fine particulates 50 are moved to the deposition trough 48.
Referring now to
As shown in
Once the sand mold packages 100 have been printed, they are removed from the job box 40 and then sent to a foundry to be cast. The sand mold packages 100 can be unique molds for casting a variety of die components wherein each sand mold package comprises a negative image of the die component to be cast. As used throughout this disclosure, the term “negative image” or “negative configuration” refers to an image or configuration formed in a mold that imparts a reciprocal positive image or configuration in the part cast or otherwise formed from the mold. At the foundry, the sand mold packages, such as sand mold packages 110-114 selected from the plurality of printed sand mold packages 100, are nested into a cope 116 and drag 118 frame apparatus or casting structure, as shown in
The accuracy and precision of the casting of the die components is within a range of accuracy of approximately 1-5 mm, or more preferably plus or minus 0.8 mm. Thus, the cast die components require very little extra machining stock, approximately 1 mm to 1.5 mm to be added. With the reduced amount of stock as compared to standard sand casting methods, which produce approximately 10 mm of extra machining stock, the cast die components of the present invention can be hardened and ground at a mounting base 122, shown in
The present invention imparts several benefits as compared to the traditional casting process in that there is a significant reduction of time-to-market because the timeline to produce a completed die set can be reduced as much as 10 to 17 days. Another significant benefit is the elimination of design constraints on the die components. Since the sand mold packages are printed using the additive manufacturing technique described above, traditional limitations found in subtractive manufacturing are eliminated, such that complex sand mold packages can be created for casting die components having complex geometries and functionality. Further, due to the accuracy of the casting, some features of the die components, which currently require time consuming post-casting machining, may be left as cast or require little to no finish machining For example, bore holes 124 and counter bore holes 126, as shown on the trim steel 120 of
As described above, Styrofoam® or CNC machining of billets can be used to create pattern parts which are later used to form molds for casting die components. The present invention also relates to using additive manufacturing techniques to create a pattern part which is later used for the creation of a mold for casting a die component. Of the additive manufacturing techniques mentioned above, one preferred process is an additive manufacturing technique using a polymeric powder containing poly(methyl methacrylate) (PMMA) as a base building material to form a polymeric pattern part. As used throughout this disclosure, the additive manufacturing process using the PMMA powder will be referred to as the PMMA process. One of ordinary skill in the art will appreciate that other additive manufacturing techniques can be used to create a pattern part for later use in a casting process.
As shown in
Once the pattern part is created, it is taken to a foundry for the creation of a shell to be used in an investment casting process. In order to use the pattern part in an investment casting process, the part 220 is submerged or otherwise coated in a ceramic slurry, which coats the entire part 220. The part is then dipped or otherwise introduced into a fluidized bed of sand, ceramic-sand, or other like powder material, which sticks to the liquid ceramic slurry. Once the sand from the fluidized bed of sand has been applied, the liquid ceramic slurry and sand mixture dries and hardens, and the process is then repeated multiple times to form a hard ceramic shell about and around the pattern part. Once a shell of sufficient thickness is formed, the shell containing the pattern part is then heated, such that the polymeric pattern part disposed within the ceramic shell burns away or vaporizes. Thus, after the heating process, the operator is left with a ceramic shell comprising a negative image of the pattern part. Using an investment casting or shell casting process, molten material, such as tool steel, is poured into the ceramic shell having the negative image of the pattern part. After the molten material solidifies, the ceramic shell is broken away or otherwise destroyed to reveal the cast metal part which, in accordance with the present invention, would be a die component, such as die component 120 shown in
Using this PMMA process, an accurate and precise pattern part representing a die component can be made layer by layer, such that complex geometries can be formed within the pattern part to produce a die component cast having a near net-shape of the pattern part. As noted above with the three-dimensional sandprinting process, the PMMA process also reduces the post-casting rough machining and finishing steps that are often required to make a finished die component. Die components cast using the PMMA pattern part as described above can have an near net-shape of the pattern part within an accuracy range of approximately 1-5 mm. Further, it is contemplated that the range of accuracy can be within plus or minus 0.8 mm of the pattern part from which the shell is formed.
The mold core packages and methods of making tools from the mold core packages, such as, but not limited to, die components, as disclosed herein provide an improved ability create configurations with an optimized wall thickness and heat treat depth as needed, thereby reducing the potential for warpage, cracks, etc. In addition, the accuracy associated with making the mold core packages from the printing process provides for better part quality, precision, and design flexibility. Further, the mold core packages and the die components made from the mold core packages can be designed to improve cycle time, thereby increasing part manufacturing capacity.
It will be understood by one having ordinary skill in the art that construction of the described invention and other components is not limited to any specific material. Other exemplary embodiments of the invention disclosed herein may be formed from a wide variety of materials and additive manufacturing techniques, unless described otherwise herein.
It is also important to note that the construction and arrangement of the elements of the invention as shown in the exemplary embodiments is illustrative only. Although only a few embodiments of the present innovation have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements shown as multiple parts may be integrally formed, the operation of the interfaces may be reversed or otherwise varied, the length or width of the structures and/or members or connector or other elements of the system may be varied, the nature or number of adjustment positions provided between the elements may be varied. It should be noted that the elements and/or assemblies of the system may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Accordingly, all such modifications are intended to be included within the scope of the present innovations. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the desired embodiment and other exemplary embodiments without departing from the spirit of the present innovations.
It will be understood that any described processes or steps within described processes may be combined with other disclosed processes or steps to form structures within the scope of the present invention. The exemplary structures and processes disclosed herein are for illustrative purposes and are not to be construed as limiting.
It is also to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.
This application is related to the following applications: U.S. patent application Ser. No. ______, filed on Feb. 29, 2012, entitled “MOLD CORE FOR FORMING A MOLDING TOOL” (Atty. Docket No. 83203377); U.S. patent application Ser. No.______, filed on Feb. 29, 2012, entitled “MOLDING ASSEMBLY WITH HEATING AND COOLING SYSTEM” (Atty. Docket No. 83203379); U.S. patent application Ser. No. ______, filed on Feb. 29, 2012, entitled “INTERCHANGEABLE MOLD INSERTS” (Atty. Docket No. 83203382); U.S. patent application Ser. No. ______, filed on Feb. 29, 2012, entitled “MOLD CORE PACKAGE FOR FORMING A POWDER SLUSH MOLDING TOOL” (Atty. Docket No. 83225801); and U.S. patent application Ser. No. ______, entitled “MOLDING TOOL WITH CONFORMAL PORTIONS AND METHOD OF MAKING THE SAME” (Atty. Docket No. 83225806), the entire disclosures of which are hereby incorporated herein by reference.