JP2018537290A - Methods for improving the heat treatment of castings. - Google Patents

Abstract

Configured to acquire multiple raw castings of a given design, capture the 3D surface measurement dimensions of the raw casting, determine a reference shape, and support the casting during heat treatment Obtaining a first support fixture having a first support profile, and then applying a heat treatment protocol to the first cast while being supported on the first support fixture. To improve the heat treatment. The method captures the three-dimensional surface measurement dimension of the first casting, determines its post-processing shape, compares the reference shape with the post-processing shape of the first casting, and is insufficient in the heat treatment protocol. Identifying dimensional distortion that is a result of proper support or positioning.

Description

  The present invention relates generally to methods for improving the heat treatment of castings during heat treatment cycles such as solution heat treatment, quenching, and aging, and in particular to methods for improving the heat treatment of castings formed in the HPDC process.

  Historically, heat treatment of thin-walled aluminum alloy castings formed by the high pressure die casting (HPDC) process has been problematic, and in many cases defective components and so as to improve their metallurgical properties and performance in high demand applications. High waste rate. For example, these types of castings often have complex shapes, surface features, openings, and variations in their cross-sectional thickness, which can be heat treated in a uniform manner during typical mass production processes. Is difficult to apply to castings. A non-uniformly applied heat treatment often creates a large temperature gradient through the thickness of the alloy material during or throughout the heat treatment, after the heat treatment is complete and the casting returns to ambient equilibrium temperature. It has been found that this can result in dimensional distortion that remains set in the casting material. In addition, castings can also be prone to distortion, especially if not properly supported during a heat treatment such as a solution heat treatment cycle, which increases its temperature to an elevated level that softens the alloy material, Allows thin wall portions to hang down under their own weight, or to deflect or buckle under the weight of the heavier overlying portion. Regardless of whether caused by a temperature gradient or by drooping or buckling, if the dimensional distortion of the casting after heat treatment exceeds a predetermined tolerance, the casting is generally discarded.

  Previous attempts to control sagging, deflection, or buckling generated during solution heat treatment through an improved casting support system are known to those skilled in the art, but include full position fixtures not shown. Perfect position fixtures are tightened tightly or very precisely around the casting immediately after their removal from the mold and reduce drooping and other distortions that can pull metal parts out of dimensional tolerances, It moves with the casting throughout the heat treatment to support and restrain the casting firmly. However, perfect position fixtures become more difficult to create with increasing casting complexity and variability and due to their presence itself, which often results in thermal fluids to parts of the casting material. The flow may be interrupted or blocked, thereby exacerbating the temperature gradient within the part. This can lead to the formation of internal stresses that cause the casting to lose shape when the full position fixture is removed after the heat treatment is complete.

  In addition, during heat treatments (eg, solution heat treatment and quenching) that apply large and / or rapid temperature changes to the part to reduce or avoid the creation of large temperature gradients within the part and throughout the part. Previous attempts to control the application of hot fluids (eg, heated air, cooling air, water, oil, glycol, and the like) to castings have also yielded limited success.

  Briefly described, one embodiment of the present disclosure includes a method for improving the heat treatment of a casting, particularly as a mass production casting, due to enhanced metallurgical properties. The method includes obtaining a plurality of raw castings of a given casting design, followed by capturing a three-dimensional surface measurement dimension of the raw casting and determining a reference three-dimensional shape for the casting. . The method includes obtaining a first support fixture having a first support profile configured to support a casting in at least one heat treatment zone, and then in one or more heat treatment zones. Applying the heat treatment protocol to the first casting supported on the first support fixture. The method captures a three-dimensional surface measurement dimension of a first casting, determines its post-processing three-dimensional shape, compares the reference shape with the post-processing shape of the first casting, and then a heat treatment protocol. Further identifying one or more correctable dimensional distortions in the first casting that are a result of poor support or positioning therein. The method then obtains a second support fixture configured to support the casting using a second support profile that is different from the first support profile and a second support protocol for the heat treatment. Continue to apply to the second casting supported on the fixture. The method captures a three-dimensional surface measurement dimension of a second casting, determines its post-processing three-dimensional shape, compares the reference shape to the post-processing shape of the second casting, and then dimensional distortion. Further verifying that the dimensional distortion is due, at least in part, to poor support or positioning during the heat treatment protocol.

  Another embodiment of the present disclosure includes obtaining a plurality of raw castings for a given casting design, after which the casting 3D surface measurement dimensions are captured and a reference 3D shape for the casting is determined. Including a method for improving the heat treatment of the casting due to the enhanced metallurgical properties to be followed. The method is substantially complementary to the lower surface of the casting, together with an open support surface configured to loosely support the casting over the grid and direct the casting into the space above the support fixture. It also includes obtaining a support fixture having an open grid structure with a plurality of upper edges defining. The method includes applying a heat treatment protocol to a first casting supported on a support fixture, capturing a three-dimensional surface measurement dimension of the first casting, and determining a three-dimensional shape after the processing. Comparing the reference shape with the post-process shape of the first casting and then identifying dimensional distortion in the first casting.

  When the correctable dimensional distortion in the first casting is the result of insufficient support or positioning during the heat treatment protocol, the method together defines a second open support surface that is different from the first support fixture. Obtaining a second support fixture comprising an open grid having a plurality of upper edges, applying a heat treatment protocol to a second casting supported on the second support fixture, Capturing the three-dimensional surface measurement dimensions of the casting, determining its post-processing three-dimensional shape, comparing the reference shape of the second casting with the post-processing shape, and reducing dimensional distortion in the second casting By identifying, one can continue to verify that the dimensional distortion is due at least in part to insufficient support or positioning during the heat treatment protocol.

  Alternatively, when the correctable dimensional distortion in the first casting is a result of the high gas content in the alloy material, the method uses a second heat treatment protocol supported on the support fixture. Applying to the casting; capturing the three-dimensional surface measurement dimensions of the second casting; determining the post-processing three-dimensional shape; comparing the second casting reference shape to the post-processing shape; By identifying the reduction in dimensional distortion in the second casting, it can continue to verify that the dimensional distortion is at least partially due to the high gas content in the alloy material. In one aspect, the second heat treatment protocol further includes reducing the time period during which the second casting is subjected to a temperature above a predetermined silicon solution temperature of the alloy material.

  These and other aspects, features, and advantages of the disclosed methods will be reviewed by reviewing the detailed description set forth below, taken in conjunction with the accompanying drawings, briefly described as follows: It will be apparent to those skilled in the art.

FIG. 1 is a perspective view of a thin wall aluminum alloy casting as is known in the art. FIG. 2 is a top view of a flat casting support tray as is known in the art. FIG. 3 is a perspective view of a representative HPDC aluminum alloy casting to which various heat treatment methods or embodiments of the present disclosure may be applied. 4 is a perspective view of the plurality of castings of FIG. 3 supported on a casting support system in accordance with an exemplary embodiment of the present disclosure. FIG. 5 is a perspective view of a casting support system and contoured casting, according to another representative embodiment. 6 is a cross-sectional side view of the casting support system and casting of FIG. 5, as viewed from section line AA. FIG. 7 is a perspective view of the casting support system of FIG. 5 as viewed from the opposite side. 8 is an enlarged view of one end of the cross-sectional side view of FIG. FIG. 9 is a top view of a casting support system, according to another representative embodiment. 10 is a schematic cross-sectional side view of the casting support system of FIG. 9 as viewed from section line BB. FIG. 11 is a schematic cross-sectional side view of the casting support system of FIG. 9 as viewed from section line CC. FIG. 12 is a temperature versus time graph of the temperature experienced by an aluminum alloy casting during a heat treatment protocol, according to another exemplary embodiment of the present disclosure. FIG. 13 is a side view of the casting of FIG. 3 after passing through a heat treatment protocol with a dimension displacement contour map superimposed on the outer surface to indicate the location and extent of various heat treatment induced dimensional strains. FIG. 14 is a cut-away side view of the casting of FIG. 13 after passing through a heat treatment protocol in which a dimensional displacement map is overlaid on the inner surface to show the location and extent of various heat treatment induced dimensional strains. 15 is a schematic diagram of a thermal processing system for implementing a portion of the thermal processing protocol of FIG. 12, according to yet another exemplary embodiment of the present disclosure. FIG. 16 is a schematic diagram of another thermal processing system for implementing a portion of the thermal processing protocol of FIG. 12, according to another exemplary embodiment of the present disclosure. FIG. 17 is a schematic diagram of another thermal processing system for implementing a portion of the thermal processing protocol of FIG. 12, in accordance with yet another exemplary embodiment of the present disclosure. FIG. 18 is a schematic diagram of a multi-stage quench system for implementing a portion of a heat treatment protocol, according to another exemplary embodiment of the present disclosure. FIG. 19 is a temperature versus time graph representing the temperature change of the casting throughout the multi-stage quench process of FIG. FIG. 20 is a schematic diagram of another multi-stage quench system for implementing a portion of a thermal treatment protocol, according to yet another exemplary embodiment of the present disclosure. FIG. 21 is a schematic side view of a forced air quench system for implementing a portion of a thermal treatment protocol, according to another exemplary embodiment of the present disclosure. FIG. 22 is a schematic side view of another forced air quench system for implementing a portion of a thermal processing protocol, according to yet another exemplary embodiment of the present disclosure. 23 is a cross-sectional schematic diagram of a thermal fluid stream impinging on a casting conveyed by the casting support system of FIG. 6 during a portion of a heat treatment, according to yet another exemplary embodiment.

  One skilled in the art, according to common practice, does not necessarily depict the various features of the drawings discussed below to scale, and the various features of the drawings and the dimensions of the elements are described herein. It will be appreciated and understood that embodiments of the present disclosure that may be scaled up or down to more clearly illustrate.

  The following description is provided to enable teaching of exemplary embodiments of methods and systems for improving the heat treatment of castings due to enhanced metallurgical properties. Those skilled in the art will recognize that changes can be made to the described embodiments while still obtaining beneficial results. It will also be apparent that some of the desired benefits of the described embodiments can be obtained by selecting some of the features of the embodiment without utilizing other features. Let's go. In other words, features from one embodiment or aspect can be combined with features from other embodiments or aspects in any suitable combination. For example, any individual or collective feature of a method aspect or embodiment may be applied to an apparatus, product, or component aspect or embodiment, and vice versa. Thus, those skilled in the art will recognize that many modifications and adaptations to the described embodiments are possible and may even be desirable in certain situations and are part of the present invention. Accordingly, the following description is provided as illustrative of the principles of an embodiment rather than a limitation thereof, as the scope of the invention is defined by the claims.

  In FIG. 1-23, to improve the heat treatment (eg, solution heat treatment, quenching, aging, etc.) of the casting, specifically, to provide enhanced metallurgical properties while reducing the waste rate, Several exemplary embodiments of methods and systems for improving the heat treatment of thin wall aluminum alloy castings formed by a die casting (HPDC) process are illustrated. As described below, the disclosed methods and systems can provide several significant advantages and benefits over other heat treatment methods and systems for castings, particularly HPDC castings. However, the advantages described are not intended to be limiting in any way as those skilled in the art will appreciate that other advantages may be realized in accordance with practicing the present disclosure. .

  In FIG. 1, an exemplary thin-walled aluminum alloy casting 10, specifically, a shock tower for an automotive suspension system, which represents a type of casting with a complex shape that has become increasingly common in recent years. 12 is shown. For example, recent advances in casting system design and processes have enabled the integration of multiple stamped sheet metal parts and fasteners, which are manufactured separately in advance, and can be combined into a single complex shock tower casting 12. When assembled together as a shock tower assembly in, a single complex shock tower casting 12 is substantially lighter in weight while providing equal or improved structural performance. Weight loss is particularly attractive in electric vehicles to improve battery life. However, these complex thin-walled aluminum alloy castings 10 are also subject to sand casting, low pressure die casting, and high vacuum due to their greater number of process steps, increased setup and equipment costs, and limited manufacturing rates. It can also be expensive to manufacture using a more conventional and expensive casting process such as die casting.

  The less equipment intensive high pressure die casting (HPDC) process has the potential to provide these same complex castings at higher speeds and reduced casting costs. However, the HPDC process has its own characteristics and drawbacks. For example, when molten metal is introduced under high pressure and speed, the gas present in the mold cavity and the evaporated liquid are often taken up by the alloy material and formed using other casting methods It can result in solidified castings containing higher amounts of dissolved gas. These dissolved gases are often distributed unevenly or irregularly throughout the part and can form regions of increased concentration. The dissolved gas tends to move out of solution during the heat treatment and form microbubbles in the alloy material that are relatively harmless at low concentrations. However, in the region of increased concentration, microbubbles can coalesce over time at elevated temperatures and depending on their location within the structure of a particular casting, stacking crack defects near the surface that impair its finish And forms larger bubbles or porosity inside the casting that can form blisters and manifest as remoter generalized dimensional strains on the outer surface. Although surface defects are generally easy to visually identify, dimensional distortion due to internal porosity is reduced by dimensional distortion due to insufficient support or positioning in the heat treatment protocol described above. It can be difficult to distinguish. This can be particularly problematic for thin wall castings with complex shapes such as the shock tower 12 shown in FIG.

  FIG. 2 is an illustration of a universal casting tray 20 of the type generally known in the art for supporting castings when transported through a heat treatment furnace and possibly through subsequent quenching and aging stages. is there. Such a casting tray 20 is typically planned and designed to support one or more castings at a time while repeatedly undergoing the same thermal cycle that the casting undergoes only once. As can be seen, these casting trays 20 generally comprise a plurality of thick wall ribs 22 made from a variety of materials including cast iron, carbon steel, and alloys thereof, ceramics, graphite and the like, wherein the ribs 22 are spaced apart. Are placed and interconnected to form an opening 24 that allows the thermal fluid to easily pass through the tray before or after contacting the supported casting. The casting tray 20 can often include additional structural features such as thick wall circles 23 at rib intersections that reduce the dimensional distortion of the tray over time and over use. Universal casting trays 20 are often intended to carry a variety of different types of castings throughout their service life, with ribs 22 and upper edges 26 of circles 23 prior to introduction into the heat treatment process. It is understood that it defines a planar non-continuous upper support surface 28 on which a casting can be placed.

  According to general practice, it can be very expensive to shut down the heat treatment furnace during the production process and allow it to cool down in order to recover the falling casting, Generally, they will be placed on the support surface 28 of the casting tray 20 in their most stable orientation so that they do not shift, roll or slide out of the support tray while passing through the heat treatment furnace. This type of casting support system 20 is self-supporting and is suitable for many types of castings including heavy or thick wall castings such as engine blocks, head covers, and transmission casings that are easily exposed on the upper support surface 28. On the other hand, it has proven effective over time. However, for complex thin wall castings such as the shock tower 12 shown in FIG. 1, the part is raised above the softening temperature, thereby causing the part of the part to hang or shift under its own weight. The most stable orientation may not provide sufficient support for all parts of the casting. In addition, the most stable orientation may position the part in a way that prevents or prevents the applied thermal fluid from reaching certain parts of the casting, during heat treatment, through the thickness of the alloy material, or It can result in a large temperature gradient across the entire surface. As explained above, either situation can result in dimensional distortion that can cause the part to be discarded.

  FIG. 3 is a perspective view of an exemplary thin wall aluminum alloy casting 100 to which various methods or embodiments of the present disclosure may be applied to improve the heat treatment of the casting 100 due to enhanced metallurgical properties. Can be done. This exemplary high performance production casting 100 can be formed by a high pressure die casting (HPDC) process and includes various thin wall portions 103, thick wall portions 105, openings 107, and reinforcing ribs 109, as well as various complexities. Surface features can be included. In the orientation shown in FIG. 3, the casting 100 can further include an outer or upper surface 104 and an inner or lower surface 106.

  In one aspect, the casting 100 of FIG. 3 can be designed and configured for use as a shock tower 102 in a vehicle suspension system. However, the method of the present disclosure is not limited in application to shock towers, HPDC components intended for the automotive industry, or even castings formed with the HPDC process. Instead, the disclosed method can be applied to transportation-based industries such as automobiles, aerospace, railroads, and ships, process-based industries such as oil and gas, chemical and paper, coils, oil, natural gas, wind, solar, It will be appreciated that it can be applied to a wide variety of high cast parts intended for use in a wide variety of industries including, but not limited to, the nuclear power and power generation industries such as geothermal.

  In general, casting 100 includes an initial formation in the HPDC process, followed by a manufacturing process followed by one or more heat treatments to provide the part with the desired range of metallurgical properties necessary for structural performance in a particular application. Can be the type intended for mass production. However, prior to the start of full-scale production, the above-mentioned problems associated with the HPDC process are reduced or mitigated, thereby producing cast parts with improved metallurgy properties with improved yield and efficiency at reduced waste rates. It may be desirable to determine both the heat treatment protocol for the casting 100 and the casting support configuration that will be produced. Alternatively, it may be desirable to improve or update an existing mass production process for casting 100 for the same reason.

  Toward these goals, one method of the present disclosure can begin by obtaining multiple or sample sets of raw test castings 100 (ie, shock tower 102) for a given production casting design. In one aspect, this can be a set of prototype castings formed during the development of a mold that will be used during full-scale production, while in another aspect, a sample set of test castings 100 is It can be a production casting drawn from an existing manufacturing process before the heat treatment stage. In either case, the casting 100 is allowed to cool or stand for a period of time in a temperature controlled environment and at a predetermined measurement temperature that is approximately at or at ambient or room temperature. It is possible to reach a state of thermal equilibrium.

When thermal equilibrium is reached at the measurement temperature, digital three-dimensional (3D) measurements of the entire surface geometry of the outer surface of the test casting 100 are captured and stored in digital form in the memory of an electronic processor-based computer system. Can do. One such measurement system for capturing 3D surface measurements is the ATOS Triple Scan ^™ surface measurement system provided by GOM mbH ^™ headquartered in Braunschweig (Germany). In general, 3D measurements of both the upper outer surface 104 and the lower outer surface 106 of the test casting 100 are captured, processed, and stored to determine a digitized three-dimensional reference external shape of the casting in the sample set. Can. In some aspects, any internal cavity or volume that is large enough to receive the sensing head of the measurement system and with sufficient access can be captured and stored in the computer system. Further, in one aspect, the three-dimensional surface measurement dimensions of each of the raw test castings 100 can be compared to identify and compensate for any discrepancies in the casting process.

  The method further includes obtaining a customizable support fixture configured to support the casting 100 with a first support profile in one or more heat treatment zones or systems. One embodiment of a casting support system 110 that includes a customizable support fixture 140 is illustrated in FIG. The casting support system 110 generally includes a base frame or tray 120 having a thickness and a top surface 122 that defines a horizontal reference plane 124. The tray 120 allows heated fluid such as heated air, cooling air, water, oil, etc. to pass unobstructed by the reference plane 124 of the tray and collide with one or more castings 100 supported above the reference plane 124. It also includes a plurality of vertically aligned tray openings or apertures 126 through the tray thickness 128 that allow for. Depending on whether the thermal fluid is applied from below the casting, from above, or applied laterally inward toward its side, the thermal fluid encounters the casting 100. The tray opening 126 can be passed before or after. In one aspect, the tray 120 extends between a peripheral frame 130 having a pair or pairs of side bars 132 joined together by a pair of end bars 134 and between the side bars in the middle of the end bars 134. One or more crossbars 36 that together define a tray opening 126 within the peripheral frame 130. The various components forming the tray 120 can be manufactured from structural steel materials.

  The tray 120 generally rides on a chain, roller conveyor, or similar transport mechanism while transporting the casting 100 through one or more thermal treatment zones such as a furnace, quench system, oven, etc., to subject the casting to heat treatment. It will be understood that they are configured as such. In some embodiments, the trays 120 can be used in a continuous process in which a plurality of trays 120, each supporting a group of castings 100, are sequentially conveyed through a heat treatment zone. In some aspects, the tray 120 can ride directly on a roller or chain, while in other aspects, the tray provides an interface between the transfer mechanism and the tray 120 that provides an interface. (Not shown). In other embodiments where the heat treatment is applied in a separate batch furnace or quenching system, the tray 120 is a robot arm, forklift truck, shuttle cart, or similar manipulator that moves the tray and casting group between heat treatments. Can be adapted for transport by.

  The casting support system 110 is attached to a tray 120 that supports and aligns a casting 100 such as the exemplary automotive vehicle shock tower 102 shown in FIG. 3 in the space above one or more tray openings 126. One or more customizable support fixtures 140 are further included. Each support fixture 140 generally includes a plurality of vertically oriented support plates with a lower portion 144 extending across the tray opening 126 and an upper edge 146 extending above the tray opening 126. 142 and the upper edge 146 of the support plate 142 has a shaped profile extending along the length of the support plate. In one aspect, each of the support plates 142 can intersect at least one other support plate to form an open grid 150 having a plurality of top edges, the plurality of top edges as shown in the drawings. Together defining an open support surface or support profile that is substantially complementary to or consistent with the lower surface of the casting 100. However, in other aspects (not shown), the support plates may not intersect each other, and instead are joined using beams or brackets to define an open support surface, such as parallel non-intersecting rows, etc. It can be aligned in another configuration. The various components forming the upper edge of the support fixture 140, in particular the support plate 142 in contact with the casting 100, can be made from stainless steel material.

  While not limited to any particular type of casting, the casting support system 110 is a thin walled aluminum alloy formed by the HPDC process by reducing many of the problems associated with the heat treatment of these parts described above. It may be particularly suitable for supporting castings. For example, the customizable support fixture 140 is configured to support each casting 100 at a primary location during a high temperature solution heating process while still providing direct thermal fluid access to substantially the entire casting surface. Can be. In this manner, the casting support system 110 can promote a uniform and uniformly applied heat treatment while preventing sagging, which uniformly increases the overall temperature of the part. Or, as it is lowered, it reduces the internal temperature gradient across the part being processed.

  Additional aspects of the casting support system 210 can be seen in FIGS. 5-8, where another customizable support fixture 240 is uniquely shaped in the space above the tray opening 226. Individually configured to securely engage and support a cast 200 (such as a thin wall aluminum alloy HPDC shock tower 202 for another vehicle, outlined in FIG. 5). As indicated above, the support fixture 240 provides direct access to the lower surface 206 where thermal fluid can be otherwise blocked by substantially the entire surface of the casting 200, in particular, the tray 220 or the support fixture 240. The casting 200 can be supported in a manner that makes it possible to have In addition, the fixture 240 is located above the tray opening 226 so as to better impart heat into the alloy material of the casting 200 in a uniform manner or to extract heat away from it. The casting 200 can also be oriented in space to align portions of the upper surface 204 and / or the lower surface 206 of the casting with the impinging thermal fluid flow.

  As illustrated in the cross-sectional side view of the casting support system 210 and the casting 200 provided in FIG. 6, in some applications, the casting 200 may include an upper surface 204 and a lower surface 206 along the length of the cross-section. It can contain highly irregular and complex shapes, as indicated by the irregular outline. In addition, the thickness of the casting 200 between the upper and lower surfaces also varies significantly along the cross-section, and the thin wall portion 203 that can be rapidly heated or cooled, and the target change in temperature. It can result in a relatively thick wall portion 205 or a structurally dense and heavy portion 207 that requires additional heat input or extraction to achieve. If similar parts are simply installed on the flat top surface of a universal casing tray (such as the casting tray 20 shown in FIG. 2), the heavier thick wall portion of the casting is raised and the thin wall portion Will be understood to be supported by. As a result, if the yield strength of the alloy material is reduced in the heat treatment process by softening at the solution temperature, the thin-walled part is sufficient to support the weight of the heavier part of the casting without deflection and deformation. It may not be sturdy.

  The casting support system 210 of the present disclosure independently separates each section of the casting including each of the heavy portion 207 or thick wall portion 205 and the thin wall portion 203 at a major location 248 across the entire underside of the casting 200. By supporting it, this difficulty can be overcome. This is accomplished by providing the upper edge 246 of the support plate 242 with an irregularly shaped profile along their length that is at least partially complementary to the irregular lower surface 206 of the casting. be able to. When the support plate is assembled and optionally interconnected together to form the grid 250, the plurality of upper edges 246 of the grid 250 do not necessarily coincide with the lower surface 206 of the casting, but substantially Defines an open support surface or support profile that is complementary thereto. As will be appreciated by those skilled in the art, the support surface is not continuous, but instead is defined only by the upper edge 246 of the support plate 242 that forms a narrow contact line pattern or grid under the casting. So it is “open”. The remaining majority of the “surface” is virtual and open to the polygonal flow area or channel, which is defined by the vertical support plate and the tray opening 226. To the lower surface 206 of the casting 200, a separate thermal fluid flow can be directed upward.

  The support surface defined by the plurality of upper edges 246 of the support plate 242 is such that the casting can only fit over the grid 250 or can be securely engaged by the grid at a single location. The lower surface 206 of the 200 can be substantially complementary. This engagement with the grid can include a plurality of contact locations 248 having both vertical components that can withstand the weight of the casting and horizontal components that prevent the casting from moving or shifting laterally. Thus, when the casting 200 is put in place on the support fixture 240, it is when the casting tray 220 is moved through one or more heat treatment sections and is subjected to various applied loads by impinging thermal fluid. Can be maintained firmly in its position. For example, the casting support system 210 includes heat treatment (including, but not limited to, high pressure air or water injection during a quench cycle) that will tend to move or shift parts that are not very well supported on the casting tray to another location. Can be used) to facilitate the use of a directed flow of high speed thermal fluid.

  Nevertheless, even though the support surface defined by the plurality of upper edges 246 of the support plate 242 can be substantially complementary to the underside of the casting 200, it is along the length of the support plate 242. Need not exactly match the lower surface 206. The support surface is instead separated by a gap 247 in which the upper edge 246 is spaced from the lower surface 206 by a distance that is sufficient to allow thermal fluid to flow between the two surfaces. Individual contact locations 248 may be included. In one aspect, the contact location 248 between the grid 250 and the lower side 206 of the casting 200 may be susceptible to sagging or distortion if not directly supported by the support fixture 240. It can be well placed at a given primary location over the entire surface. In this way, the casting 200 is supported in the space above the opening 226 using a reduced number of primary contact locations 248 while leaving the rest of the casting surface directly accessible by thermal fluid. be able to.

  In FIG. 6, a static heat treatment zone 290 is also shown, which is a thermal fluid that impinges on the exposed upper surface 204 of the casting 200 (eg, heated air in the heat treatment zone or cooling air in the quench zone). ) Of an upper plenum 294 having a downwardly directed nozzle 295 or outlet to produce one or more downwardly directed flows 296, and a thermal fluid impinging on the exposed lower surface 206 of the casting 200. And a lower plenum 297 having an upwardly directed nozzle 298 or outlet for generating one or more upwardly directed flows 299. In addition, the customizable fixture 240 that supports the casting 200 is itself coupled to a tray 220 that is transported over the rollers 292 of the roller transport system through the heat treatment zone 290. In one aspect, both the downward directed flow 296 and the upward directed flow 299 can be substantially aligned with the thick wall portion 205 and the structurally dense portion 207 of the casting 200; Thereby, more heat can be applied to or extracted from these portions of the casing than directly adjacent thin-walled portions that require less heat transfer to achieve the same change in temperature. Further, in one aspect, the support surface defined by the plurality of upper edges 246 of the support plate 242 aligns the thick wall portion 205 and the structurally dense portion 207 with both sets of nozzles 295,298. The casting 200 can be positioned and directed in the space. In addition, the upwardly directed flow 299 of the thermal fluid is substantially disturbed by both the tray opening 226 and the grid 250 of the cross support plate 242 so as to impinge on the lower surface 206 of the casting 200. Can pass without.

  FIG. 7 is a perspective view of the casting support system 210 of FIGS. 5-6 without casting, in this case formed by four intersecting vertical support plates 242 mounted on the tray 220 above the tray opening 226. A customizable fixture 240 is illustrated. As can be seen, in this embodiment, the peripheral frame 230 of the tray 220 can include multiple pairs of side bars 232 with cylindrical cross sections, which side bars 232 have rectangular cross sections at their ends. Coupled to end bars 234 or crossbars 236, they together define a plurality of tray openings 226 within the peripheral frame 230. In one aspect, side bars 232, end bars 234, and crossbar 236 are sized and configured together to form a standardized tray 220 that can serve as a base frame with standardized dimensions. A variety of differently configured fixtures 240 can be removably and interchangeably mounted on the tray opening 226. In addition, the peripheral frame 230 and the lower surface of the crossbar 236 can ride directly on the rollers 292 of the transport system (FIG. 6), and in one aspect can be extended or shortened according to the desired application. In the modular tray 220, damaged side bars or end bars / crossbars can be individually connected without the need to replace the entire tray 220. It can be removed and replaced with an undamaged component.

  The customizable fixture 240 of the exemplary support system 210 can include four support plates 242 oriented vertically, with the support plates 242 extending below the tray opening 226. A portion 244 and an upper edge 246 that together form a grid structure 250 extending above the tray opening 226, the upper edge 246 having an open support surface or support profile for castings in the grid structure 250. Is defined. In one aspect, the support plate 242 can be substantially aligned with the main horizontal axes 212, 216 of the peripheral frame 230, and the lower edge 244 extends across the length or width of the tray opening 226. In another aspect (not shown), the support plate can be aligned diagonally with respect to the main horizontal axis of the peripheral frame 230 or at another angle. With respect to the two support plates 252 of the exemplary fixture 240 aligned parallel to the longitudinal axis 212 of the peripheral frame 230, the lower ends are notched 253 that engage the inner edges of the rectangular end bar 234 and the cross bar 236. And may not extend across the centerline of the crossbar 236 so as not to interfere with fixtures overlying adjacent tray openings. For the two support plates 256 aligned parallel to the width axis 216 of the peripheral frame 230, the lower ends can extend outward past the side bars 232 and are formed at their lower edges A notch 257 can be included, and the notch 257 engages a mounting bar 238 that extends upward from the top surface of the cylindrical side bar 232.

  In one aspect, the support plates 242 can cross and connect to each other in place and are downwardly open half slots formed in the upper pair of support plates 256, as is known in the art. Defined by an upwardly opening half-slot formed in a pair of lower support plates 252 that fit together. In this manner, the support plates 242 of the support fixture 240 can be interlocked together to form the grid 250 prior to attachment to the tray 220. Further, as described in more detail below, the position of the interlocking support plates 252, 256 within the grid 250 repositions the contact location 248 of the upper edge 246 under the portion of the casting that requires maximum support. It can be modified relative to each other and to the peripheral structure of the tray 220 for placement. In the illustrated embodiment, this can be accomplished by adjusting the location of the half-slot along the length of the support plate, with the end of the support plate extending to the end bar 234 or the crossbar 236. Along the mounting bar 238 on the side bar 232 or along the side bar 232. Nevertheless, it will be understood that other connection methods or mechanisms for connecting the support plates 242 to each other and to the tray 220 are possible and are considered to fall within the scope of this disclosure.

  Also visible in FIGS. 5-7 are a plurality of openings 245 that can be formed through the thickness of the support plate 242 that allows thermal fluid to flow laterally through the support plate. As shown in FIGS. 5 and 7, in one aspect, the opening 245 can be elongated in the direction of the vertical axis 218 of the support system 210. This is due to the flow directed upwards of the thermal fluid due to the minimal amount of flat surface area and corners oriented perpendicular to the path of the thermal fluid, which can impede its passage and reduce its velocity. A grid support structure 250 that is largely “permeable” may be provided. However, in another aspect of the support fixture 240 shown in FIG. 6, the openings 245 in the vertically aligned support plate can be elongated in the direction of the main horizontal axes 212, 216 of the support system 210. . This results in a support structure 250 with a much larger amount of flat surface area and corners oriented perpendicular to the path of the thermal fluid, thereby reducing its velocity while increasing its turbulence and mixing. A greater degree of disturbance to the upwardly directed flow of the thermal fluid can be generated. It will be appreciated that depending on the application, both options may be used to provide improved heat transfer into or away from the lower surface of the casting.

  The casting 200, similar to the thin wall aluminum alloy HPDC shock tower 202 shown in FIGS. 5-6, often has a thin wall projection of alloy material that protrudes outward to define an outer edge 209 or flange (FIG. 5). Can be included. These thin-walled structures that are not supported along one side can often be more susceptible to deflection or deformation during heat treatment and thus other castings that are substantially surrounded by the alloy material. May require a greater degree of support or restraint than the thin wall interior section. In order to provide this extra support, in one aspect, the end of the support plate 242 can include an upwardly extending protrusion 249 that restrains the outer edge 209 of the casting.

  FIG. 8 is an enlarged view of the left end of the support plate 242 of FIG. 6 and illustrates an upwardly extending protrusion 249 that restrains one outer edge 209 of the casting 200. In one aspect, the lower inner edge of the protrusion 249 can include a notch 255 that is sized to receive the outer edge 209 of the casting after considering thermal growth of both the casting and the support plate during heat treatment. In addition, the upper edge 246 of the support plate 242 can provide a contact line extending at a contact location 248 along the lower surface 206 of the cast thin wall portion 203 proximate the outer edge 209. Both the extended contact line defining the proper location of the thin wall portion 203 and / or the notch 255 that prevents the outer edge 209 from pulling upward during heat treatment maintain alignment during multiple heat treatments, It will be appreciated that it may serve to prevent deformation of the outer edge portion.

  The support fixture 240 illustrated in FIGS. 5-7 provides a firm support for the casting 200 at a single location and prevents it from being accidentally removed from the fixture during heat treatment. The casting 200 can be engaged along both the lower surface 206 and the outer edge 209. In other embodiments, such as the casting support system 110 illustrated in FIG. 4, the support fixture 140 primarily has its main feature to securely support the casting in a single position without necessarily engaging the outer edge. The casting 100 can be engaged along the lower surface.

  FIG. 9 shows that four of the support plates 352 extend in parallel with the longitudinal axis 312 of the base tray 320, and four support plates 356 extend in parallel with the width axis 316 of the base tray 320. FIG. 6 is a top view of another exemplary embodiment of a casting support system 310 that also includes a fixture 340 with a crossed support plate. When assembled, the support plates 352, 356 together have nine polygonal flow channels 360 that can guide the thermal fluid flow upward from the tray opening 326 to the lower surface of the casting (not shown). Define. In this embodiment, the one or more support plates may also include deflectors 362, 366 that extend outward into the channel to redirect the thermal fluid flow toward the opposing support plate. In one aspect, the deflector 362 extends outward and upward in the flow direction 363 to redirect flow toward the opposite side of the same channel, as shown in the cross-sectional schematic of FIG. Can do. In another aspect, the deflector 366 is outwardly and flowable to redirect flow through an opening 368 in the support plate and toward the opposite side of the adjacent channel, as shown in the cross-sectional schematic of FIG. It can extend downward against the direction 367.

  Additional details and information regarding the casting support system disclosed above may be found in SYSTEM FOR SUPPORTING CASTINGS DURING THERMAL TREATMENT, filed September 23, 2015, which is hereby incorporated by reference in its entirety. Co-owned copending US Provisional Patent Application No. 62 / 222,407.

  As described above with reference to FIGS. 3-4, the method of the present disclosure generally includes a support profile that is configured to initially support the casting 100 within one or more heat treatment zones or systems. Obtaining one or more support fixtures 140 having In one aspect, each initial support profile is defined by an open grid 150 of a support fixture 140 formed from a plurality of support plates 142, and the upper edge of the support plate is substantially complementary to the lower surface 106 of the casting 100. Together defining an open support surface configured to loosely support the casting 100 on the grid 150 in an initial position and orientation in the space above the tray opening 126. In addition, the open support surface is provided by a gap in which the upper edge of the support plate 142 is spaced from the lower surface 106 of the casting 100 to allow direct thermal fluid access to substantially the entire lower surface 106. It may further include a plurality of individual predetermined contact locations that are separated. Although shown as a group of four support fixtures 140 that support four test castings 100 on a single casting tray 120, the desired test is more like performing a test cycle in a more economical manner. It will be appreciated that this can be done with fewer support fixtures 140 and casting 100. Once the reference surface measurement of the aluminum alloy casting 100 is captured in three dimensions and the initial or first support fixture is acquired, the initial or first heat treatment protocol is supported on the support fixture 140 by one or more. The test casting 100 can be applied.

  In one aspect of the present disclosure shown in the temperature vs. time graph of FIG. 12, the heat treatment protocol 400 includes three separate heat treatment stages: a first heating stage 420, a second heating stage 430, and a quenching stage 440. Can be included. The first heating stage 420 includes a predetermined solution temperature 414 of the silicon component of the aluminum alloy without the casting entering the furnace and reaching or exceeding the predetermined silicon solution temperature 414 from the initial temperature 421. A first time period (t1) 424 that is heated to a first casting temperature 425 that is less than. For example, without being bound by any particular theory, the internal “pore making” process, which leads to the formation and expansion of internal pores or bubbles in the casting, the silicon component of the aluminum alloy as the casting reaches the silicon solution temperature. It is considered by the inventors to start with being taken up by the solid solution. As silicon is incorporated into the solution, the size of the silicon particles appears to shrink as the overall number of silicon particles appears to increase, thereby causing the entrained gas in the casting to move through the material. Make it possible to do. Eventually, however, the trend is reversed as smaller silicon particles grow together into larger particles, which prevents or impedes gas movement. The trapped gas then coalesces together into the bubbles or pores, which will continue to grow as long as the casting is maintained at an elevated temperature. If left unchecked, enlarged bubbles or pores near the surface can break through the surface as blisters, while enlarged bubbles or pores inside the casting can cause dimensional distortion.

  Since the solution temperature of the silicon component is distinguishable from and less than the solution temperature of the one or more metal alloying components, the solution heat treatment of the aluminum alloy ultimately results in the desired improvement in mechanical properties. It is theorized that the castings will not begin until the castings are heated to their alloying metal solution temperature. Thus, by recognizing and taking into account the difference between the silicon solution temperature and the alloying metal solution temperature, prior to quenching, both at the silicon component solution temperature 414 and the metal alloying component solution temperature 418, or Beyond that, the time spent by the casting (t3) 436 can be controlled to produce an aluminum alloy casting with excellent mechanical properties with reduced waste rate, the casting otherwise It is further considered to have a substantial reduction in dimensional distortion that would be due to the formation of enlarged bubbles of trapped gas.

  It will be appreciated that both the casting duration (t1) 424 and the first heating rate 422 in the first heating phase 420 may vary substantially between different embodiments of the heat treatment protocol 400. . For reference purposes, the rise / time of the first heating rate 422 is defined as ° C./min, as the instantaneous heating rate or, for example, the entire first heating stage 420 or one of the first heating stages 420. It can be applied as an average heating rate during a specified period such as only parts. Factors affecting duration (t1) and / or first heating rate 422 include furnace type and configuration, initial casting temperature 421 when the casting first enters the furnace, casting thickness and / or Surface area exposure and the like can be included.

  For example, in some embodiments, a casting, such as a casting for an engine block, can be very thick. It may also be preferred that substantially the entire thick casting material reaches the first casting temperature 425 prior to entering the second heating stage 430. In such an embodiment, the target heating profile heats the casting at a slower rate, then several minutes toward the end of the first heating phase 420 (eg, 2-5 minutes or a similar long period), This can be accomplished by allowing the casting to be immersed at a first casting temperature 425 and providing sufficient time for heat to be evenly distributed throughout the casting. In other embodiments, the casting is thin with a higher proportion of exposed surface area that readily receives and distributes the applied heat to reach thermal equilibrium at the first casting temperature 425 within a much shorter period of time. It can be a wall structure, in which case the thermal immersion period can be shortened or eliminated.

  In other aspects, such as the embodiment shown in FIG. 12, the casting can be heated at a substantially constant first heating rate 422 throughout most of the first heating stage 420, after which the casting is As the intended first casting temperature 425 is approached, the heating rate gradually decreases towards the end of the first heating stage. This technique provides better control of the heat treatment protocol such that the casting temperature inadvertently exceeds the first casting temperature 425 while the casting remains in the first heating stage 420, and the predetermined silicon solution. It can be ensured that the temperature 414 is not violated or reached, thereby not prematurely triggering the pore making process described above.

  In yet another aspect of the present disclosure, the first heating stage of the furnace is substantially above the first casting temperature 425 to maintain heat flow into the casting throughout the first heating stage 420. It can be maintained at a constant first stage temperature. In an embodiment, the first stage temperature is above a predetermined silicon solution temperature 414 at which the silicon component rapidly enters the solid metal solution. In an embodiment, the movement of the casting through the furnace causes the casting to have a first casting temperature 425. Can be determined to terminate the first heating stage 420 prior to reaching a thermal equilibrium with a predetermined silicon solution temperature 414 or first stage temperature. In an embodiment where the first stage temperature is less than the predetermined silicon solution temperature 414, the casting duration (t1) 424 in the first heating stage 420 coincides with the casting reaching the first casting temperature 425. It can be extended to approach thermal equilibrium with the first stage temperature.

  Thus, in one aspect, the first stage temperature of the first heating stage can be maintained within ± about 10 ° C. of the predetermined silicon solution temperature 414. In another aspect, the first stage temperature of the first heating stage 420 is the first heating stage throughout the first heating stage 420, with a corresponding decrease in the duration (t1) 424 of the first heating stage. A predetermined silicon solution temperature 414 can be maintained at a temperature 10 ° C. above to provide an increase in rate 422, and prior to reaching the predetermined silicon solution temperature 414, the casting is first heated Accurate control of casting movement through the first heating stage 420 can be included to ensure that stage 420 is finished.

  When the first casting temperature 425 is reached at the end of the first heating phase 420, the casting can then transition or transition to the second heating phase 430 of the heat treatment protocol 400, where the second heating phase 430 is In general, a second time period (t 2) 434 extends from entering the casting into the second heating stage 430, to their termination and transition to the quenching stage 440. Upon entering the second heating stage 430, the casting is rapidly heated from the first casting temperature 425 to a second casting temperature 435 that is above or substantially equal to the predetermined alloying metal solution temperature 418. The The casting may then be maintained at the second casting temperature 435 for the remaining period (t2) 434 of the second heating phase 430 in the substantially isothermal (ie, constant temperature) portion 437 of the protocol 400. it can. After entering the second heating stage 430, the substantiality of the heat treatment protocol 400 at the second casting temperature 435 depends on the time required to heat the casting from the first casting temperature 425 to the second casting temperature 435. The isothermal portion 437 can typically range from about 10 minutes to about 20 minutes. Nevertheless, substantially isothermal portions 437 that are less than 10 minutes in duration, such as 5-10 minutes in duration, are possible and are considered to be within the scope of this disclosure.

  In one aspect, the second casting temperature 435 does not excessively exceed the alloying metal solution temperature in a manner that can lead to harmful side effects, and the metal alloying components in all parts of the casting are alloyed metal solution temperature. The predetermined solution temperature 418 of the metal alloying component can be above about 5 ° C. to 10 ° C. to ensure that it reaches or exceeds and enters the solid solution. In other aspects, such as when the alloying metal solution temperature is precisely known and the heat treatment protocol 400 can be tightly controlled, the second casting temperature 435 can be a predetermined solution temperature 418 of the metal alloying component. May exceed 5 ° C or less.

  As shown in FIG. 12, in one aspect, the heating of the casting in the second heating stage 430 suddenly exceeds the casting heating rate in the first heating stage 420 just prior to entering the second heating stage 430. Can be accompanied by an initial or a second heating rate 432 that is increased. This may result in a step increase in casting temperature up to a second casting temperature 435 within a shortened period, where the casting temperature 412 is within a given silicon solution temperature 414 within a few seconds of entering the second heating phase 430. To reach. For example, typically, it may take 3-5 minutes at the initial or second heating rate 432 for the casting to reach a predetermined alloyed metal solution temperature 418, although the temperature of the casting is nevertheless The predetermined silicon solution temperature 414 can be reached and exceeded immediately after entering the second heating stage 430. Indeed, the casting temperature enters the second heating phase 430, particularly when the first casting temperature 425 at the end of the first heating phase 420 is within a few degrees of the predetermined silicon solution temperature 414. Within 60 seconds or less, the predetermined silicon solution temperature 414 can be reached and exceeded. Thus, in one aspect, the time that the casting spends above the predetermined silicon solution temperature 414 can be substantially equal to the time (t2) 434 spent in the second heating stage 430, the characteristics of which are Can be used to simplify calculations.

  In addition, the second heating stage 430 of the furnace is substantially constant above the first stage temperature so as to maintain heat flow into the casting at least during the first portion of the second heating stage 430. The second stage temperature can be maintained. In one aspect, the additional heat input required to rapidly raise the casting temperature to the second casting temperature 435 directs additional heat over the casting, and the initial second heating rate 432. Can be provided by additional heating devices such as directed heaters or high flow hot air nozzles that can provide enhancements. Further, the additional heating device is configured to increase the casting temperature to the second casting temperature 435 within a shortened period without increasing the second stage temperature in the second heating stage portion of the furnace. Can.

  When the casting reaches a second casting temperature 435 associated with the substantially isothermal portion 437 of the protocol 400, the second stage temperature is reduced during the remainder of the period (t2) 434 of the second heating stage 430. It is possible to prevent the heat flow away from the. In one aspect, the second stage temperature can be substantially equal to the second casting temperature 435, while in the other aspect, the second stage temperature is the second heater with the casting temperature remaining. May be slightly higher than the second casting temperature 435 so that it continues to rise slightly during the phase (typically only a small amount due to the relatively short time remaining in the second heating phase). . In one embodiment, the second stage temperature may be less than about 10 ° C. above a predetermined alloying metal solution temperature 418 at which at least one metal alloying component rapidly enters the solid metal solution.

  The time period (t3) 436 in which the casting spends at or above the predetermined solution temperature 418 of the metal alloying component is measured from entering the second heating stage 430 to entering the quenching stage 440. Compared to the overall duration (t2) 434 of the two heating stages 30, the (t3) / (t2) timing ratio of the casting at the alloying metal solution temperature 418 can be 50% or more. This timing ratio may also be known as the time ratio during the procedure. As will be appreciated by those skilled in the art, the time ratio during the treatment is in addition to or exceeding the silicon solution temperature at which the silicon component rapidly enters the solid metal solution, as well as metal alloying. At or above the alloying metal solution temperature at which the components rapidly enter the solid metal solution, or above, it can be a good approximation of the actual percentage of time the casting spends in the solution heat treatment. It is also understood that the in-treatment time ratio provided by the present disclosure can be substantially increased over solution heat treatment methods for HPDC castings currently known and practiced in the art. Let's go.

  Indeed, depending on the difference between the predetermined silicon solution temperature 414 and the predetermined alloying metal solution temperature 418, and the difference between the first casting temperature 425 and the predetermined silicon solution temperature 414, and the furnace configuration. In some embodiments, the (t3) / (t2) in-treatment time ratio for castings at or above a given alloying metal solution temperature 418 is greater than 60%, greater than 70%, or even It is conceivable that it can be 80% or more. For example, if it is determined that the (t2) value of a particular alloy is limited to 418 minutes in order to avoid blister formation and / or the development of dimensional distortion based on a high proportion of castings, 75% (t3 ) / (T2) In-treatment time ratio can ensure that the casting is maintained at or above a predetermined alloyed metal solution temperature for about 13.5 minutes. In this way, the casting can be used to limit the time spent at or above the silicon solution temperature, thereby avoiding the negative effects of pore-based defects while reducing the beneficial effects of alloying metal solution heat treatment. A substantial increase can be obtained.

  Accordingly, heating the casting in the first heating stage 420 to the first casting temperature 425 that is in the vicinity of the predetermined silicon solution temperature 414 reduces the heating requirements in the second heating stage 430 and the casting is first It may be advantageous both for reducing the time required to reach a predetermined alloying metal solution temperature 418 when heated to the second casting temperature 435 in the second heating stage 430. Will be understood.

  Upon reaching the end of the second heating phase 430, the casting is rapidly cooled from the second casting temperature 435 to a quench temperature 445 that is generally less than 250 ° C. but still well above ambient temperature. Transition to or transition to the quench phase 440 of the heat treatment protocol 400. The quench stage 440 generally comprises a liquid spray cooling system, a forced air or gas cooling system, a liquid immersion cooling system, or a combination of the above. During the quench phase 440, the casting can be cooled at a cooling rate 442 over a period (t4) 444 that generally ranges from 1 minute to about 5 minutes. After completion of the quench phase 440, the casting is removed to the atmosphere and allowed to cool for T4 temper and allow aging to proceed naturally, or to achieve a T6 temper for a predetermined period of time. Can be removed to a separate temperature control chamber (not shown but known to those skilled in the art) for artificial aging at high temperatures. Other quenching and aging protocols are possible and would be considered within the scope of this disclosure, as will be appreciated by those skilled in the art.

  Additional details and information regarding the heat treatment protocol 400 disclosed in FIG. 12 are filed on Apr. 28, 2015, SYSTEM AND METHOD FOR THERMAL TREATING, which is hereby incorporated by reference in its entirety. It can be found in co-owned co-pending US provisional patent application 62 / 153,724, entitled ALUMINUM ALLOY CASTINGS. However, the heat treatment protocol 400 described above is only one exemplary embodiment of the present disclosure, and other different heat treatment protocols are also applied to the test casting 100 supported on the support fixture 140 (FIG. 4). It is understood that they are also considered to fall within the scope of this disclosure.

  Upon completion of the initial or first heat treatment protocol, one or more treated test castings 101 (as opposed to the untreated casting 100 prior to or during the heat treatment) were again temperature controlled. Within the environment, it may be possible to cool or stand for a period of time and reach a state of thermal equilibrium at a predetermined measured temperature. At this point, the method can proceed to capture the second digitized three-dimensional surface measurement dimension of the test casting 101 to determine the post-processing three-dimensional shape, after which the part shape The post-treatment shape can be compared to a reference shape to determine if and during the heat treatment protocol and, if applicable, the location and amount. For example, as shown in the side view of FIG. 13 and the cut side view of FIG. 14, in one aspect, this electronically combines the digitized reference shape and the digitized post-process shape of the casting 101, This can be accomplished by creating a three-dimensional contour map or model 180 of the casting 101 that can illustrate one or more regions 182, 184 of substantial dimensional distortion. If these dimensional changes exceed a predetermined tolerance, then the disclosed method may then cause the dimensional distortion 182, 184 to cause thermal fluid flow with respect to poor support during the heat treatment protocol, the position and orientation of the casting 101 within the heat treatment zone. It can proceed to identify whether it is the result of improper application or the development of significant porosity inside the casting that indicates an excessive amount of dissolved gas in the alloy material. It will be appreciated that combinations of the above causes of distortion are possible, and in some cases, multiple methods for reducing distortion may also be required.

  A general indication of a large amount of dissolved gas and porosity inside the casting is a blister on the outer surface of the treated casting 101, and in one aspect, the surface of the treated test casting close to dimensional distortion is the alloy material. It can be checked to identify the surface porosity associated with the increased concentration of dissolved gas in it. However, it is possible to have a high gas content internal local region that causes external dimensional distortion without significant accompanying surface blistering or defects. In this case, the casting can also be cut close to the dimensional strain to identify the internal porosity associated with the high gas content in the alloy material.

  If it is determined that the dimensional strain 182, 184 in the treated test casting 101 is a result of high gas content in the alloy material, in one embodiment, the method includes internal porosity in other untreated test castings. The application of a second different heat treatment protocol intended to eliminate or substantially reduce the occurrence of gender related distortions can continue. For example, to verify that at least part of the cause of dimensional distortion is the high gas content in the alloy material, the initial or proposed heat treatment protocol for the green casting 100 can be seen with reference to FIG. As explained above, it can be modified by reducing the time period during which the casting is subjected to a temperature above the predetermined silicon solution temperature 414 of the alloy material. This can be accomplished in a variety of ways, depending on the type of heat treatment zone or system (ie, furnace) used to apply the first and second heating stages in the heat treatment protocol.

  For example, as shown in the temperature versus time plot of FIG. 12, the casting 100 passes through the first transition zone 429 as it transitions between the first heating stage 420 and the second heating stage 430, It can then pass again through the second transition zone 439 between the second heating phase 430 and the quenching phase 440. The second transition zone 439 will typically include physical movement of the casting from inside the furnace to a quenching station located outside the furnace, such as through a discharge door at the exit end of the furnace. However, the first transition zone 429 between the first heating stage 420 and the second heating stage 430 typically has a physical barrier, depending on the type of furnace used to perform the heat treatment. Either moving through or increasing the heating rate. As described in more detail below, for example, a process furnace that continuously moves castings through a heated interior volume on a conveyor system may include an interior door that defines a boundary between the two stages. Alternatively, a batch furnace that heats the casting in place increases the heating rate and quickly increases the casting temperature 412 from the first casting temperature 425 to the second casting temperature 435. Additional heaters that can be active in the zone, high flow hot air nozzles, or similar heating devices can be included.

  FIG. 15 illustrates a continuous process furnace 450 that includes an endless conveyor chain 452 (ie, a pair of parallel synchronized chains) that travels through an insulated enclosure 454 with an intake door 456 at the inlet end and a discharge door 458 at the outlet end. FIG. The furnace 450 can further include a number of heating cells 460 aligned in series along the length of the furnace 450, each heating cell 460 extending into the cell (eg, of the enclosure 454). Each heater cell 460 includes, for example, a heater unit and a motor driven blower, the motor driven blowers between individual chains in the conveyor chain 452 The heated air is driven downward into the enclosure 454 to flow across and around the casting 405 riding at a reduced speed through the furnace on a tray spanning the distance of The process furnace 450 shows seven heating cells 460 arranged along the length of the furnace, each heating cell 460 having its own blower-based heater assembly 462, while FIG. 15 shows the heat treatment protocol of FIG. It is only a schematic representation of one possible configuration of a process furnace 450 or system for implementing a portion of 400, and allows for a wide variety of heating cell numbers and arrangements, as well as a variety of different types of heater assemblies and techniques It will be understood that they are also considered to fall within the scope of this disclosure.

  The process furnace 450 passes the interior of the insulating enclosure 454 into a first heating stage 420 and a second heating stage 430 that are consistent with the first heating stage 420 and the second heating stage 430 depicted in FIG. An internal barrier with a dividing gate or intermediate door 464 can be included. When both stages are passed so that a single conveyor chain 452 transports casting 405 through furnace 450 at a constant speed, the speed of conveyor chain 452, the overall length of furnace enclosure 454, and the intermediate door along the length of the enclosure It will be appreciated that the position of 464 may determine the duration (t1) 424 of the first heating phase 420 and the duration (t2) 434 of the second heating phase 430. In one aspect, the duration (t2) 434 of the second heating phase 430 is 25 minutes or so to ensure that the casting 405 exits the furnace 450 prior to the occurrence of any pore-based defects. It can be limited to less than that, preferably 20 minutes or less. As a result, the heat output generated by the heating cell 460 in the first heating stage 420 then causes the temperature 412 of the casting 405 to be the first prior to or substantially simultaneously with the casting 405 reaching the intermediate door 464. The casting 405 can be adjusted to be heated at a desired first heating rate 422 to reach a casting temperature 425 of one.

  In one aspect, the temperature of the first heating stage 420 can be maintained at the first casting temperature 425, and the duration (t1) 424 is a thermal equilibrium between the casting 405 and the heated air in the first heating stage 420. Can be extended until gradually established between. The temperature of the second heating stage 430 is also increased at the beginning of the second heating stage 430 so that the casting quickly reaches a thermal equilibrium between the casting 405 and the heated air in the second heating stage 430. With heat input, it can be maintained at the second casting temperature 435.

  Also visible in FIG. 15, in one aspect, the position of the intermediate door 464 along the length of the furnace enclosure 454 has been changed to better accommodate the desired casting temperature profile for a particular aluminum alloy casting. Can be. For example, if a blank space 466 is provided between each of the heating cells 460 in the center of the furnace enclosure 454 and is filled with insulating spacers 467 when not in use, the intermediate door 464 can be a second heating stage 430 or Each can be moved upstream or downstream as desired to reassign adjacent heating cells to the first heating stage 420, respectively. This feature is provided by providing the user with additional variables beyond the speed of the conveyor chain 452 and the output of the heater assembly 462 to optimize the (t3) / (t2) time ratio in the second heating stage. It may be advantageous over a furnace having an intermediate door in a fixed position.

  Further, it is understood that the output of the heater assembly in the first heating cell of the second heating stage 430 may not be sufficient to increase the initial or second heating rate 432 to a desired value. It will be. In this case, one or more additional heating devices 468 such as additional heaters or hot air nozzles can be added to the affected heating cell, directing additional heat on the casting 405 and shortening. Provide an initial or second heating rate 432 enhancement that would raise the casting temperature to the second casting temperature 435 within a given period of time. For furnace 450 with adjustable intermediate door 464, an empty support fixture filled with an insulating plug 469 can also be provided at each additional optional location, thereby providing additional heating device 468. May be repositionable with the intermediate door 464.

  The process furnace 470 schematically illustrated in FIG. 16 illustrates another option to accommodate a desired casting temperature profile for a particular HPDC aluminum alloy casting. Similar to the previous process furnace embodiment, the process furnace 470 generally includes an intake door 476 at the inlet end, an intermediate door 484 that separates the enclosure into a first heating stage 420 and a second heating stage 430, and an outlet end. A thermal enclosure 474 is included along with a discharge door 478. The furnace 450 also includes a number of heating cells 480 aligned in series along the length of the furnace 470, each heating cell 480 being a lower casting that rides at a reduced speed through the furnace on a conveyor system. A heater assembly 482 is provided that extends downward through the ceiling and directs heated air downward into the enclosure 454 so as to impact the 405. An additional heating device 488 can also be added directly downstream of the intermediate door 484 to provide an enhancement at the beginning of the second heating stage 430 or at the second heating rate 432.

  However, in this embodiment of the process furnace 470, the position of the intermediate door 484 along the length of the enclosure 454 can be fixed and the conveyor system has a conveyor chain 472 with an independently controllable operating speed. 473 (ie, a pair of parallel synchronized chains). Two independently controllable conveyor chains 472, 473 provide the user with the ability to independently control the duration of the first heating stage (t1) and the duration of the second heating stage (t2). And thus may allow optimization of both the first heating rate 422 in the second heating stage 430 and the (t3) / (t2) in-treatment time ratio. In one aspect, two conveyor chains 472, 473 can meet in the first transition zone 429 (ie, intermediate door 484) as illustrated in FIG. 12, while in the other aspect, the conveyor chain May meet at another location within the furnace enclosure 474 such as a location downstream of the intermediate door 484 (not shown) within the second heating stage 430.

  The solution heat treatment system 550 illustrated in the plan view of FIG. 17 can include a plurality of batch-type heat treatment furnaces 560 aligned side by side. Each furnace 560 can include an insulated enclosure 562 with access doors 564 on one side, with all access doors 564 facing in the same direction. Each of the furnaces 560 can also include at least one primary heater assembly 566 that extends downwardly through the ceiling of the enclosure 562, and the primary heater assembly 566 can include, for example, a heater unit and an enclosure 562. And a motor driven blower that drives the heated air downwardly, and the enclosure 562 is spaced apart and / or laminated so that the heated air can be applied to each casting substantially uniformly. In relation, it is typically sized to receive a plurality of castings 505 loaded on a tray or rack. In one aspect, the primary heater assembly 566 can be configured to provide variable heat output, such as with a variable frequency motor drive 567 that can increase the flow of heated air into the enclosure 562. In another aspect, the heat treatment furnace 560 is added to provide an increase in the initial or second heating rate 532 that will increase the temperature of the casting 505 to the second casting temperature 535 within a shortened period of time. One or more additional secondary heaters 568 can be provided, such as heaters or high flow hot air nozzles.

  As also shown in FIG. 17, the solution heat treatment system 550 receives an access door 564 in each of the furnaces 560 so that after the casting is withdrawn from the furnace 560, the heated casting rack is received and immediately quenched. A movable quench station 570 that translates back and forth in front of (ie, the second transition zone 539) may further be included. The quench station generally includes an enclosure 572 with at least one opening 574 facing the furnace 560 for receiving a casting rack, such as a liquid spray cooling system or a forced air or gas cooling system. A cooling system 576 is also supported. In one aspect, the movable quench station 570 can be supported on a wheeled carriage that can be moved between various furnaces on rails 578. As will be appreciated by those skilled in the art, the movement of quench station 570 causes the quench station to receive the processed casting as soon as each batch of casting reaches the end of its second heating phase 530. As prepared, it can be synchronized with the heat treatment cycle taking place in each batch type furnace 560.

  For the batch heat treatment furnace 560 of the solution heat treatment system 550 of FIG. 17, the first transition 429 (FIG. 12) between the first heating stage 420 and the second heating stage 430 is the first heating stage. Can be a “virtual” transition with an increase in the rate at which the casting is heated from the first heating rate 422 to the initial or second heating rate 432 in the second heating stage 430. In one aspect, the increase in heating rate can be achieved by increasing the primary heating, such as by increasing the speed of the variable frequency motor drive 567 or by temporarily activating one or more additional secondary heaters 568 as described above. Can be achieved through increased heat output from the vessel assembly 566.

  Despite possible inefficiencies of batch-type heat treatment due to repeated heat circulation in the furnace chamber, one advantage provided by the heat treatment furnace 560 of FIG. 17 is that the duration of the first heating stage 420 (t1 ) 424 can be defined by the first heating rate 422, while the duration (t 2) 433 of the second heating phase 430 can be defined by opening the access door 564 and removing the casting 505 from the furnace enclosure 562. It is.

  Additional details and information regarding the heat treatment system disclosed above can also be found in the aforementioned US Provisional Patent Application No. 62 / 153,724, which is incorporated by reference above.

  In applying the second different heat treatment protocol to the second test casting, in the heat treatment zone, the same support fixture and support profile reduce the number of variables that can affect the results of the second test. Can be used to support castings. Upon completion of the second heat treatment protocol, the second processed casting 101 may also be allowed to cool until reaching a state of thermal equilibrium at a predetermined measured temperature, at which point the second casting 101 is separated. The digitized 3D surface measurement dimensions can be captured to determine the 3D shape after processing. After this, determine the reduction of the previously identified dimensional strain, or even the absence thereof, thereby verifying that some or all of the previous strain was due to high gas content in the alloy material Thus, similar to that shown in FIGS. 13-14, a comparison of the post-process shape of the second casting with its reference shape can continue.

  A positive indication of high gas content in HPDC castings is useful information for HPDC mold manufacturers or designers, especially when strain and dissolved gases are localized within specific areas of the casting. It will be understood that you get. With this information, the mold manufacturer can redesign the mold or HPDC process in such a way as to reduce the amount of gas available for absorption by the molten casting material. obtain. For example, in one aspect, the vents in the mold cavity provide a better escape path for gases and vapors present in the mold cavity when the hot melt is introduced at high pressure and speed. It can be modified or rearranged. In other aspects, the gate for directing molten metal into the mold cavity is also modified to better control the flow pattern so that the casting material fills the cavity and pushes gas and vapor through the vents Or it can be rearranged.

  Referring again to FIGS. 4 and 13-14, it is determined that the dimensional distortion 182, 184 in the treated test casting 101 is the result of insufficient support provided by the support profile of the first support fixture 140. The relative positions of the support plates 142 and / or the shape of their upper edges may be determined by the second or modified support fixture open support surface (ie, support profile) and the lower or side edges of the casting 101. Can be modified to adjust the contact location between the two. For example, if the strain is identified as being caused by sagging, the support fixture 140 then includes an additional contact location between the upper edge of the support plate and the casting 101 and is affected during the production process. Can be modified to better support the part. This can be done by repositioning the support plate under the affected part or by adding a new support plate and / or the upper edge of the support plate already located under the affected part. Can be achieved by reshaping.

  The initial or first heat treatment protocol is then re-applied to the second casting supported on the second fixture to reduce the number of variables that can affect the results of the second test. be able to. Upon completion of the second step through the first heat treatment protocol, the second casting may also be allowed to cool until reaching a state of thermal equilibrium at a predetermined measured temperature, at which point the processed second Another digitized three-dimensional surface measurement dimension of the two castings 101 can be captured to determine the post-processing three-dimensional shape. After this, determine the reduction of the previously identified dimensional distortion, or even its absence, so that part or all of the distortion is due to insufficient support provided by the first support fixture. To verify the post-process shape of the second casting with its reference shape, similar to that shown in FIGS. 13-14. At this point, the support fixture for the mass production process can then be manufactured with a second support profile.

  As discussed above, dimensional distortion 182, 184 in the treated test casting 101 remains specifically set in the casting material after the heat treatment is complete and the casting returns to ambient equilibrium temperature. Can be the result of incomplete or improper application of thermal fluid to castings in heat treatment zones in a manner that creates large temperature gradients through the thickness of the alloy material that leads to dimensional distortion or across its entire surface There is also. Further, improper application of hot fluid is generally a problem during the quench phase 440 of the heat treatment protocol 400 (FIG. 12). This is because the cooling rate 442 during quenching is much higher than the heating rates 422, 432 during the heating phase and the various parts of the casting are substantially equal to each other during the rapid transition from the final casting temperature 435 to the quenching temperature 445. This is because it is difficult to maintain the relative temperature. It is the inventors that improvements in heat treatment of castings that reduce dimensional distortion can be achieved through control or modification of the type and orientation of the thermal fluid applied to the casting, the position and orientation of the casting relative to the thermal fluid flow, or both. Have been determined.

  For example, in another aspect of the present disclosure shown in FIG. 18, the quenching phase 440 can be performed by a multi-stage quenching system 600 that generally includes a housing 620 that includes an enclosure 622 that surrounds the quenching chamber 626. Inside, one or more high temperature castings (represented as a single test casting 100 in the drawing) are positioned using the same support system 110 that supports the castings during the heat treatment phase of the thermal protocol 400. obtain. As explained above, the support system 110 extends upward from the tray 120 to keep the casting loose in the desired position and orientation within the quench chamber 626 and over its lower surface and / or lower edge. Support fixture 140 may be included that contacts the casting at several locations across, but both support fixture 104 and tray 120 otherwise prevent various cooling fluid streams from reaching the casting. Most of them are open or empty so as not to.

  Multi-stage quench system 600 generally also includes a pressurized liquid spray cooling system 630 and a bulk air cooling system 640. The liquid spray cooling system 630 can include a source of pressurized cooling liquid in fluid communication with a plurality of nozzles 632 with nozzle heads 634 through one or more manifolds 631. The nozzle 632 is configured to spray the cooling liquid 636 onto the hot casting 100 during one or more portions of the quench cycle to provide liquid spray quench. The cooling liquid 636 can generally comprise water or a mixture of one or more additional liquid components, such as water and glycol. In addition, the nozzle head 634 provides the cooling liquid 636 in various states, from high pressure / high velocity flow with large droplets to atomized mist formed from droplets having an average size of less than 100 μm or about 100 μm. Can be configured as follows. In another aspect, the temperature of the cooling liquid 636 prior to dispersion from the nozzle can be maintained at a predetermined temperature that is optimized to provide the desired cooling effect.

  The nozzle 632 and nozzle head 634 of the liquid spray cooling system 630 can be configured in both direction and flow rate to provide precision control for the application of the cooling liquid 636 on the high temperature casting 100 to extract heat therefrom. It can be. For example, the configuration of individual nozzles 632 and nozzle head 634 may increase the amount of cooling liquid 636 applied to the thicker portion of the test casting relative to the amount of cooling liquid applied to the thin wall portion of the casting. Alternatively, it can be customizable either manually or by programmable actuation to suit a particular cast part. Furthermore, the cooling liquid can be applied simultaneously on all sides or exposed surfaces of the casting (ie, front, back, sides, bottom, top, or interior). In this way, the casting can be cooled in a substantially uniform manner throughout the liquid spray cooling portion of the quench cycle. Since the relative temperatures of the various parts of the casting can be maintained substantially equal throughout the quench cycle, any thermally induced internal stress and the resulting dimensional distortion of the casting is substantially Can be reduced.

  Bulk air cooling system 640 enters quench chamber 626 through inlet 624, traverses the outer surface of hot casting 100 to remove heat from the casting, and passes around it, then 1 as exhaust stream 648. One or more rotatable cooling fans 642 may be included that are configured to provide a bulk flow of cooling air 644 that escapes from the chamber 626 through one or more outlets 628. In one aspect, the temperature and flow rate of the bulk cooling air 644 can be controlled to provide desired cooling characteristics. For example, the motor driving the rotatable cooling fan 642 can be powered by a variable frequency drive (VFD) that can provide a continuously variable bulk flow of cooling air over a wide range of operating speeds or frequencies. Bulk air cooling system 640 and chamber 626 ensure that cooling air 644 passes through substantially the entire exposed outer surface of the casting and allows casting to be cast in a substantially uniform manner throughout the forced air cooling portion of the quench cycle. It can also be configured to cool.

  Further, as will be appreciated by those skilled in the art, the configuration of the bulk air cooling system 640 depicted in FIG. 18 only illustrates a generalized bulk air system that provides a cooling air 644 flow surrounding the casting 100. Absent. This is configured so that the cooling fan 642 is positioned above or below the chamber 626 or even remotely from the chamber and draws or pushes cooling air through the chamber and across the casting from any direction. Because it can be done. In practice, the heated exhaust 648 can be mixed with the flow from the liquid spray cooling system 630 at any time, thus drawing cooling air 644 into the chamber from below and in the opposite direction as illustrated in FIG. In addition, it may be advantageous to discharge the mixed exhaust 648 and heated water vapor through an outlet located in the upper portion of the chamber 626.

  The multistage quench system 600 generally also includes a programmable controller 616, such as a computer or similar electronic processor based device, configured to activate and deactivate the bulk air cooling system 40 and the pressurized liquid spray cooling system 630. Accordingly, the controller 616 adjusts the cooling provided by the liquid spray cooling system 630 and the bulk air cooling system 640 to ensure that each type of casting 100 can undergo a specific pre-programmed quenching process. Can be used. In one aspect, the controller 616 can also be used to automatically adjust the liquid positioning and flow rates through the individual nozzles 32 as described above. Alternatively, the quench system 600 may utilize a basic timer system in which a defined defined time schedule is used to continuously activate and deactivate each of the cooling systems 630, 640.

  Also shown in FIG. 18 is an optional temperature sensing system 610 that can measure and monitor the surface temperature of the casting 100 through the use of one or more temperature sensors 612. In one aspect, the temperature sensor 612 can remotely measure the surface temperature of the casting at one or more locations without touching the surface, such as with an infrared sensor. In other aspects, the one or more temperature sensors may be located directly on or within the cast part. Telecommunication can be established between the temperature sensor 612 and the programmable controller 616 through the control wiring 614, which monitors and records the reduction of the casting surface temperature when undergoing a quenching process. Used to do.

  Once the high temperature casting 100 is positioned or secured within the quench chamber 626, the bulk air cooling system 640 and the liquid spray cooling system 630 use a predetermined series of quenching stages or steps to rapidly quench the casting. Can be operated independently, or together. For example, one exemplary embodiment of utilizing the multistage quench system 600 of the present disclosure, as may be applied to an aluminum alloy casting, is represented below. In particular, a temperature vs. time graph of an exemplary process 650 for quenching an aluminum alloy casting is provided in FIG. 19 (also known as a quenching profile), where the casting temperature 652 depends on the bulk air cooling system 640 and the liquid. It can be reduced quickly and uniformly in three or more different stages or phases, including alternating operation of the spray cooling system 630. As discussed above, this rapid but controlled reduction in casting temperature 652 in a substantially uniform manner can result in high strength parts with minimal dimensional distortion.

  Prior to entering the first stage (“stage I”) 660 of the quench process 650, the high temperature casting is placed in the quench system at an initial temperature 662, such as an elevated post-heat treatment temperature as the casting exits the solution furnace. Can be installed. Bulk air cooling system 640 can then be activated to provide stage I air quench 664 for cooling the casting from an initial temperature 662 to a first intermediate temperature 672. Stage I air quench 664 occurs during stage I period 666, which in one embodiment can last from about 5 seconds to about 20 seconds. In some aspects, stage I cooling rate 668 can be substantially linear or constant (as also shown in FIG. 19), while in other aspects, stage I cooling rate 668 is non-linear or variable. It can be.

  At the end of the first phase 660 of the quench process 600, the bulk air cooling system 640 can be deactivated and the liquid spray cooling system 630 is moved from the first intermediate temperature 672 to the second intermediate temperature 682. It can be activated to provide a second stage (“stage II”) liquid (or liquid / air) spray quench 674 that further cools the casting. Stage II spray quench 674 can have a duration 676 that, in one embodiment, can last from about 5 seconds to about 20 seconds. In some aspects, the stage II cooling rate 678 can be substantially constant, while in other aspects, the stage II cooling rate 678 can be variable.

  After the casting temperature reaches the second intermediate temperature 682, the liquid spray cooling system 630 can be deactivated and the bulk air cooling system 640 is cast from the second intermediate temperature 682 to the final quench temperature 692. Can be reactivated to provide a third stage (“stage III”) air quench 684 that further cools the air. Stage III spray quench 684 can have a period 686 that, in one embodiment, lasts from about 5 seconds to about 10 seconds. In some aspects, the stage III cooling rate 688 can be substantially constant, while in other aspects, the stage III cooling rate 688 can be variable. When the Stage II cooling liquid is water, Stage III air quench can also function to dry any residual moisture that remains on the casting after Stage II spray quench 674. After reaching the final quench temperature 692, the casting can be allowed to cool 144 gradually to ambient temperature for natural aging, or before it is allowed to cool naturally, It can be transferred to a secondary furnace for artificial aging at high temperatures and for extended periods of time.

  As discussed above, each of the air quench stages 664, 684 and the spray quench stage 674 cools the casting in a substantially uniform manner throughout the quenching, and can be thermally generated in the part. It can be configured to reduce the induced stress. This feature of the present disclosure minimizes or substantially reduces thermally induced dimensional distortion, which can result in some castings that are otherwise generated during the quench process and rejected because they are out of dimensional tolerances. Can be functionally reduced.

  In one embodiment, the total time for performing the multi-stage quench process 650 on the high temperature aluminum alloy casting from the initial temperature 662 to the final quench temperature 692 can range from about 15 seconds to about 50 seconds. Although the multi-stage quench process 650 can take longer than immediate immersion quench in water and oil as currently available in the art, the ability to variably control the cooling rate of the casting throughout the quench process is It can result in a quenched casting with improved metallurgical properties and reduced dimensional distortion. In some aspects, the multi-stage quench process 650 is an additional that artificially ages castings at high temperatures in secondary furnaces when used to complete a properly optimized solution heat treatment process. It is contemplated that this step may be provided with such improved metallurgical properties that may not be necessary to meet structural performance requirements.

  The multistage quench system 600 and quench process 1650 illustrated in FIGS. 18-19 are batch or cell based quench systems where each stage in the quench process is performed on the casting at the same location, It will be appreciated that it can be substantially fixed within the space or at least within the chamber 626 of the enclosure 620. However, it is also possible that a mass-produced casting will undergo a multi-stage quench process 650 while moving through a continuous process quench system, such as the quench system 700 illustrated in FIG. It's even more likely.

  The multi-stage quench system 700 generally includes a plurality of castings (not shown) in a chamber 706 at a substantially constant rate 701 from an inlet opening 704 at one end of the enclosure 702 to an outlet opening 708 at the opposite end. And an elongate enclosure 202 that defines a quench chamber 206 that travels therethrough. Enclosure 702 can include a first section 710 having a bulk air cooling system 712 that provides stage I air quench 664 (FIG. 19). Depending on the speed 701 at which the casting travels through the enclosure 702, the first bulk air cooling system 712 may include one or more cooling fans 714 that provide a bulk flow of cooling air through the chamber 706. In one aspect, the cooling fan 714 may be adjustable to accommodate the various types of castings with different quench profiles, the cooling rate provided within the stage I air quench 664 of the quench system 700. VFD drive can be provided so that the bulk flow of cooling air is continuously variable over a wide range of operating speeds.

  After passing through the first section 710, the casting can then enter a second section 720 having a liquid spray cooling system 722 that provides stage II spray quench 674 (FIG. 19). The liquid spray cooling system 722 may include a row of nozzles 724 with a nozzle head 726 that sprays a cooling liquid, such as water or a water / glycol mixture, onto the hot casting during the intermediate stage II portion of the quench process.

  Upon reaching the end of the second section 720, the casting can then enter a third section 730 having another bulk air cooling system 732 that provides stage III air quench 684 (FIG. 19). Similar to the first bulk air cooling system 712 proximate the inlet of the enclosure 702, the second bulk air cooling system 732 also includes one or more cooling fans depending on the speed 701 at which the casting travels through the enclosure 702. 734 may be included. The cooling fan 734 in the third section 730 of the quench system 700 can also be provided with a VFD drive so that the cooling rate provided in the stage III air quench 734 can be adjustable.

  As also shown in FIG. 20, the multi-stage quench system 700 is an optional temperature sensing system that can measure the surface temperature of the casting through the use of a plurality of temperature sensors 762 that can be spaced along the length of the enclosure 702. 760 may also be included. In other aspects, the one or more temperature sensors may be located directly on or within the cast part. Although not shown, the temperature sensing system 760 telecommunications a programmable controller as described above that can be used to monitor, control, and record a reduction in casting surface temperature as it passes through the quench system 700. It is understood that you get.

  Referring again to FIGS. 4 and 13-14, it is determined that the dimensional distortion 182, 184 in the treated test casting 101 is the result of incomplete or improper application of thermal fluid to the casting in the heat treatment zone. In one aspect, the multi-stage quench system 600, 700 disclosed in FIGS. 18-20 controls the type and direction of thermal fluid applied to the casting during the quench phase, in a substantially uniform manner. It can be used to reduce the thermal gradient and cool the casting rapidly. This multi-stage quench approach can be particularly effective when combined with the support system 110 and the support fixture 140, while the support fixture 140 can support the casting in the space within the quench chamber. Otherwise, it is largely open or empty so as not to prevent the various cooling fluid streams from reaching the casting.

  Additional details and information regarding these multi-stage quench systems were filed on September 16, 2015 and entitled SYSTEM AND METHOD FOR QUENCHING CASTINGS, which is incorporated herein by reference in its entirety. , Co-owned copending US Provisional Patent Application No. 14 / 855,498.

  Alternatively, in yet another aspect of the present disclosure shown in FIG. 21, the quench phase of the thermal protocol generally includes a quench housing 820 that includes a plurality of sections extending across the central portion 822 of the quench housing 820. This may be done by a single stage forced air quench system 800 for cooling a casting 880 with at least one roller conveyor system 830 having support rollers 832. Cooling air that flows upward through the housing such that a forced air fan (not shown) exits through one or more openings (also not shown) in the upper portion of the quench housing. To provide 890 flow, it can be located in the lower portion of the quench housing 820. Roller conveyor system 830 moves one or more casting trays 860 loaded with casting 880 into a central portion 822 of quench enclosure 820 that will encounter cooling air 890 provided by a forced air fan. Consists of.

  The quench air system 800 may also include a plurality of nozzle baffles 840 that extend inwardly from the sidewall 824 of the quench housing 820 to the inside of the outermost roller 832 of the roller conveyor. The nozzle baffle 840 flows upward along the side wall 824 of the quench housing 820 toward the central portion of the quench housing 820, thereby the velocity of forced cooling air 890 as it flows upward through the casting tray 860. Can be operated to redirect these portions 892 of the cooling air 890. In one aspect, the nozzle baffle 840 extends upward adjacent to the inner edge of the outermost roller 842 without contacting the roller so as to maximize the increase in cooling air 890 speed while minimizing pressure loss. May include a fixed upward and inwardly inclined portion 842 that curves aerodynamically into the vertical lip 846. However, other configurations and / or shapes of the nozzle baffle 840 are possible and are considered to fall within the scope of this disclosure.

  Although not shown in the schematic side view of FIG. 21, a similar nozzle baffle also extends inwardly from the sidewall of the quench enclosure 820 that is perpendicular to the sidewall 824 shown in the drawing (ie, into or out of the drawing paper). Please understand that you get. In this case, the nozzle baffle may include a notch or cutout that fits around the roller 832. Thus, in some aspects, the nozzle baffle 840 substantially corresponds to the area occupied by the portion of the casting tray 860 that supports the casting 880 and is generally much smaller than the overall cross-sectional area of the quench enclosure 820. Forced cooling air 890 can be redirected and focused into the brazing area. Accordingly, the nozzle baffle 840 can provide a first redirecting or concentration of forced air flow and a corresponding first stage increase in the flow rate or speed of the cooling air 890.

  As also illustrated in FIG. 21, in some embodiments, the air quench system 800 includes a plurality of movable central baffles 850 that are located in the gap 834 between the support rollers 832 in the central portion 822 of the quench enclosure 820. Further can be included. Although visible from their ends in the drawing, it should be understood that the central baffle 850 can be an elongated wing-shaped structure that can be substantially the length of the support roller. In addition, the central baffles 850 can be supported at their ends or at one or more intermediate span locations so that the actuated support system is substantially from the substantially horizontal orientation shown in FIG. The central baffle 850 can be moved or rotated to a vertical orientation, as well as any desired angular orientation therebetween. When moved horizontally or tilted, the central baffle concentrates the upwardly flowing forced cooling air further back into the narrow gap or channel 836 between the central baffle 850 and the outer peripheral surface of the support roller 832. And thereby function to further increase the speed of the cooling air 890 into a given channel as it flows around and through the casting 880. This second, more local redirecting or concentration of forced air flow may comprise a second step increase in flow rate, leading to a corresponding increase in the rate at which heat is collected and drawn from the heated cast metal.

  Although not visible in the drawings, in one aspect, the width of the central baffle 850 defines channels of varying size and shape that can be optimized to better define and shape the cooling air 890 flow. As such, it can vary along the length of the wing-shaped structure (ie, moving perpendicular to the plane of the drawing). For example, in some aspects, the profile of the central baffle 850 is such that the high velocity flow of cooling air flows inwardly through the interior of the casting in addition to the high velocity flow of cooling air that flows across the outer surface of the casting 880. It can be shaped to fit a large opening 882 (eg, an empty cylinder bore or crankshaft bore) formed through the casting 880 itself so that it can be directed to flow. In this way, a greater percentage of the cooling air provided by the forced air fan can be utilized to cool the casting and thereby increase the effectiveness, efficiency, and cooling rate of the quench system 800. .

  FIG. 22 illustrates a second or upper roller conveyor 935 for cooling a casting 980 that includes two roller conveyor systems 930, 935 positioned directly above the first or lower roller conveyor 930 in the central portion 922 of the quench enclosure 920. FIG. 6 is a schematic side view of another exemplary embodiment of the single stage forced air quench system 900 of FIG. However, in this embodiment, a forced air fan (not shown) is located above the quench station so that the cooling air 990 flow provided by the fan flows downwardly through both roller conveyor systems 930, 935. Can be located. In this embodiment, since the upper casting tray 966 can be moved to a fixed position on the upper quenching station without interfering with simultaneous withdrawal of the lower casting tray 960 from the lower quenching station, the second roller conveyor 935 is useful for minimizing switching time between a first casting tray 960 loaded with a first group of castings 980 and a second casting tray loaded with a second group of castings. possible.

  Both quench stations in the quench air system 900 can include nozzle baffles 940, 946 and movable central baffles 950, 956. The nozzle baffles 940, 946 can be fixed and flow downward along the side wall 924 toward the central portion 922 of the quench housing 920, thereby passing through the casting supported on the casting tray, And it can serve to redirect these portions 992 of the cooling air 990 to focus and increase the velocity of the forced cooling air 990 as it flows downward around it. However, in this embodiment, the nozzle baffles 940, 946 are located at the top of the roller conveyors 930, 935 at each quenching station, where the casting tray loaded with castings is shown on the lower side as shown in the illustrated embodiment. It can include vertical lips 944, 948 that can extend inward from the side wall 924 by a distance 926 that allows it to roll under the nozzle baffle. In addition, since the nozzle baffle is located above the quench station, the size and shape of the nozzle baffles 940, 946 are not constrained by the roller conveyor. This may allow the nozzle baffles to be configured or customized to more closely match the area occupied by the castings 980 mounted on their respective casting trays 960 if so desired. . Since these flow areas will generally be much smaller than the total area of the quench enclosure 920, the nozzle baffles 940, 946 have a first redirection or concentration of forced air flow and a corresponding first of the flow rates. A step increase can be provided.

  Similar to the embodiment of the quench air system described above, the movable central baffle 950, 956 located near or in the mouth of the nozzle baffle 940, 946 is a second more localized redirect of forced air flow. Or, concentration and a corresponding second stage increase in flow rate can be provided. The central baffles 950, 956 may be defined and shaped to accommodate a cooling air flow to correspond with openings and / or other structures formed in the lower casting, thus adjusting the cooling flow. Molded profiles can also be provided that can be used to provide improved cooling for specific castings. However, because the movable central baffles 950, 956 are also located above the quench station and are not constrained by the roller conveyors 930, 935, the number, size, and shape of the central baffles 950, 956 are those movable mixed with the rollers. It can be substantially different from the baffle design (see, eg, the embodiment of FIG. 21).

  When a first casting tray 960 loaded with a first group of castings 980 is positioned in the lower quenching station, the central baffle 950 associated with the first station is an opening formed in the lower casting 980. Moved or rotated to their active orientation (horizontal orientation if depicted) that redirects and concentrates the forced cooling air that flows downward into narrow gaps or forming channels 935, corresponding to parts or other structures Can. At the same time, the central baffle 956 associated with the second quenching station (here upstream of the first quenching station) has their vertical so as to reduce any drag and pressure loss caused by the overlying structure. Or it can be moved to the inactive direction.

  When the first casting tray 960 is withdrawn from the lower quenching station and the second casting tray loaded with the second group of castings is positioned within the upper quenching station (not shown), it is associated with the first station. It will be appreciated that the central baffles 950 that are formed can be moved to their vertical or inactive orientation so as to reduce the back pressure generated by structures downstream of the currently quenched casting. . At the same time, the central baffle 956 associated with the second quench station is forced to flow downward into a narrow gap or forming channel 935 corresponding to an opening or other structure formed directly in the casting 986 below. It can be moved or rotated to their active orientation (eg, horizontal orientation) that redirects and concentrates the air.

  Additional details and information regarding these forced air quenches are filed on July 27, 2015, which is hereby incorporated by reference in its entirety, and is entitled SYSTEM AND METHOD FOR IMPROVING QUENCH AIR FLOW. And can be found in co-owned copending US Provisional Patent Application No. 62 / 197,199.

  In yet another aspect of the present disclosure illustrated in FIG. 23, to determine a flow pattern 293 of a thermal fluid, such as heated or cooled air, around the casting 200 and an expected heat transfer rate across the entire surface of the casting. During the development of the heat treatment protocol, numerical analysis such as thermal finite element analysis can be performed on the casting 200, the casting support system 210, and the heat treatment zone 290 (FIG. 6). The heat transfer rate is improperly balanced between the thin wall portion 203 and the thick wall portion 205 in a manner that will create a temperature gradient throughout the thickness of the alloy material and / or across its entire surface. If it is determined that the support fixture 240 is tilted, the support profile of the support fixture 240 may be used to adjust the position and / or orientation of the casting 200 within the flow pattern 293, or using one or more deflectors. 206 may be modified to improve or redirect the downward flow pattern. Thus, the casting support system 210 facilitates a uniform and uniformly applied heat treatment that reduces the internal temperature gradient across the treated casting 200 so that the overall temperature of the part is raised or lowered. Can be used for.

  In essence, the disclosed method and system is employed to improve the heat treatment of casting HPDC castings, specifically for improved metallurgical properties and to reduce dimensional distortion. Can do. The methods and systems can generally adapt heat treatment protocols to reduce or avoid many of the problems associated with mass production of thin wall aluminum alloy castings formed with the (HPDC) process. Inclusive application of the customizable casting support system described above in combination with a heat treatment system.

  The present invention has been described herein in terms of preferred embodiments and methodologies contemplated by the inventors to represent the best mode of carrying out the invention. However, it will be appreciated by those skilled in the art that a wide range of additions, deletions, and modifications, both subtle and exhaustive, can be made to the illustrated exemplary embodiments without departing from the spirit and scope of the present invention. Will be understood. These and other modifications can be made by those skilled in the art without departing from the spirit and scope of the invention, which is limited only by the following claims.

Claims (22)

A method for improving the heat treatment of a casting for enhanced metallurgical properties, said method comprising:
Obtaining a plurality of raw castings of a given casting design;
Capturing a three-dimensional surface measurement dimension of the casting and determining a reference three-dimensional shape for the casting;
Obtaining a first support fixture configured to support the casting using a first support profile in at least one heat treatment zone;
Applying a heat treatment protocol to a first casting supported on the first support fixture;
Capturing a three-dimensional surface measurement dimension of the first casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the first casting;
Identifying at least one dimensional strain in the first casting due to inadequate support or positioning during the heat treatment protocol;
Obtaining a second support fixture configured to support the casting using a second support profile different from the first support profile;
Applying the heat treatment protocol to a second casting supported on the second support fixture;
Capturing a three-dimensional surface measurement dimension of the second casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the second casting;
Verifying that the dimensional distortion is at least partially due to insufficient support or positioning in the thermal processing protocol by identifying a reduction in dimensional distortion.   Each of the first and second support fixtures further comprises an open grid having a plurality of upper edges that together define the first and second support profiles, wherein the plurality of upper edges are of the casting. 2. Complementary to a lower surface and configured to loosely support the casting over the grid and direct the casting into a space above the first support fixture. The method described in 1.   The first and second support profiles further comprise a plurality of individual contact locations separated by a gap in which the upper edge is spaced from the lower surface of the casting. The method described.   4. The method of claim 3, wherein the plurality of individual contacts on the second support profile is different from the plurality of individual contacts on the first support profile.   The method of claim 1, wherein a position and orientation of the casting in the second support profile is different from the position and orientation of the casting in the first support profile.   6. The method of claim 5, wherein applying the heat treatment protocol to the second casting further comprises modifying a thermal fluid flow directed toward the at least one dimensional strain location.   The method of claim 6, wherein the thermal fluid stream further comprises a cooling fluid in a quench process.   The method of claim 1, wherein the green casting is a pre-production prototype casting.   The method of claim 1, further comprising comparing the three-dimensional surface measurement dimensions of each of the green castings to identify inconsistencies in the casting process.   The method of claim 1, further comprising identifying at least one dimensional strain due to a high gas content in the alloy material of the first casting during the heat treatment protocol.   Identifying the at least one dimensional strain due to the high gas content is to inspect a surface of the first casting that is proximate to the at least one dimensional strain and to a high gas content in the alloy material. The method of claim 10, further comprising identifying an associated surface porosity.   Identifying the at least one dimensional strain due to the high gas content cuts the first casting proximate the at least one dimensional strain and is associated with a high gas content in the alloy material. The method of claim 10, further comprising identifying internal porosity. Applying a modified heat treatment protocol to a third casting supported on the second support fixture;
Capturing a three-dimensional surface measurement dimension of the third casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the third casting;
11. Identifying that another dimensional strain reduction is occurring and further verifying that the dimensional strain is at least partially due to the high gas content in the alloy material. the method of.   14. The method of claim 13, wherein applying the modified heat treatment protocol further comprises reducing a time period during which the casting is subjected to a temperature above a predetermined silicon solution temperature. A method of improving the heat treatment of a casting for improved metallurgical properties, said method comprising:
Obtaining a plurality of raw castings of a given casting design;
Capturing a three-dimensional surface measurement dimension of the casting and determining a reference three-dimensional shape for the casting;
Obtaining a support fixture comprising an open grid having a plurality of upper edges defining together an open support surface, wherein the plurality of upper edges are substantially complementary to a lower surface of the casting , Configured to loosely support the casting on a lattice and to direct the casting into a space above the support fixture;
Applying a heat treatment protocol to the first casting supported on the support fixture;
Capturing a three-dimensional surface measurement dimension of the first casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the first casting;
Identifying dimensional distortion in the first casting. Obtaining a second support fixture including an open grid having a plurality of upper edges, wherein the plurality of upper edges are different from the open support surface of the first support fixture. Defining the surfaces together;
Applying the heat treatment protocol to a second casting supported on the second support fixture;
Capturing a three-dimensional surface measurement dimension of the second casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the second casting;
Further comprising: verifying that the dimensional distortion is due at least in part to insufficient support or positioning in the heat treatment protocol by identifying a reduction in the dimensional distortion in the second casting. Item 16. The method according to Item 15.   The first and second open support surfaces further comprise a plurality of individual contact locations separated by a gap in which the upper edge is spaced from the lower surface of the casting. The method of claim 16, wherein the plurality of individual contacts on a support surface are different from the plurality of individual contacts on the first open support surface.   17. The method of claim 16, wherein the position and orientation of the casting on the second open support surface is different from the position and orientation of the casting on the first open support surface.   The method of claim 16, wherein applying the heat treatment protocol to the second casting further comprises modifying a thermal fluid flow directed toward the at least one dimensional strain location. Applying a second heat treatment protocol to a second casting supported on the support fixture;
Capturing a three-dimensional surface measurement dimension of the second casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the second casting;
And further verifying that the dimensional distortion is at least partially due to a high gas content in the alloy material by identifying a reduction in the dimensional distortion in the second casting. The method described.   21. The method of claim 20, wherein applying the second heat treatment protocol further comprises reducing a time period during which the second casting is subjected to a temperature above a predetermined silicon solution temperature of the alloy material. A method for improving the heat treatment of a casting for enhanced metallurgical properties, said method comprising:
Obtaining a plurality of raw castings of a given casting design;
Capturing a three-dimensional surface measurement dimension of the casting and determining a reference three-dimensional shape for the casting;
Obtaining a first support fixture configured to support the casting using a first support profile in at least one heat treatment zone;
Applying a heat treatment protocol to a first casting supported on the first support fixture;
Capturing a three-dimensional surface measurement dimension of the first casting and determining a three-dimensional shape after the processing;
Comparing the reference shape with the treated shape of the first casting;
Identifying at least one dimensional strain in the first casting.

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